Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to Geophysical Surveys in the Atlantic Ocean, 63268-63381 [2018-26460]
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DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric
Administration
RIN 0648–XE283
Takes of Marine Mammals Incidental to
Specified Activities; Taking Marine
Mammals Incidental to Geophysical
Surveys in the Atlantic Ocean
National Marine Fisheries
Service (NMFS), National Oceanic and
Atmospheric Administration (NOAA),
Commerce.
ACTION: Notice; issuance of five
incidental harassment authorizations.
AGENCY:
In accordance with the
regulations implementing the Marine
Mammal Protection Act (MMPA) as
amended, notification is hereby given
that we have issued incidental
harassment authorizations (IHA) to five
separate applicants to incidentally
harass marine mammals during
geophysical survey activities in the
Atlantic Ocean.
DATES: These authorizations are
effective for one year from the date of
effectiveness.
FOR FURTHER INFORMATION CONTACT: Ben
Laws, Office of Protected Resources,
NMFS, (301) 427–8401.
SUPPLEMENTARY INFORMATION:
SUMMARY:
Availability
Electronic copies of the applications
and supporting documents, as well as a
list of the references cited in this
document, may be obtained online at:
www.fisheries.noaa.gov/action/
incidental-take-authorization-oil-andgas-industry-geophysical-surveyactivity-atlantic. In case of problems
accessing these documents, please call
the contact listed above.
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Background
Section 101(a)(5)(D) of the MMPA (16
U.S.C. 1361 et seq.) directs the Secretary
of Commerce (as delegated to NMFS) to
allow, upon request, the incidental, but
not intentional, taking of small numbers
of marine mammals by U.S. citizens
who engage in a specified activity (other
than commercial fishing) within a
specific geographic region if certain
findings are made and notice of a
proposed authorization is provided to
the public for review.
An authorization for incidental
takings shall be granted if NMFS finds
that the taking will have a negligible
impact on the species or stock(s), will
not have an unmitigable adverse impact
on the availability of the species or
stock(s) for subsistence uses (where
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relevant), and if the permissible
methods of taking and requirements
pertaining to the mitigation, monitoring
and reporting of such takings are set
forth.
NMFS has defined ‘‘negligible
impact’’ in 50 CFR 216.103 as an impact
resulting from the specified activity that
cannot be reasonably expected to, and is
not reasonably likely to, adversely affect
the species or stock through effects on
annual rates of recruitment or survival.
The MMPA states that the term ‘‘take’’
means to harass, hunt, capture, or kill,
or attempt to harass, hunt, capture, or
kill any marine mammal.
Except with respect to certain
activities not pertinent here, the MMPA
defines ‘‘harassment’’ as any act of
pursuit, torment, or annoyance which (i)
has the potential to injure a marine
mammal or marine mammal stock in the
wild (Level A harassment); or (ii) has
the potential to disturb a marine
mammal or marine mammal stock in the
wild by causing disruption of behavioral
patterns, including, but not limited to,
migration, breathing, nursing, breeding,
feeding, or sheltering (Level B
harassment).
Summary of Requests
In 2014, the Bureau of Ocean Energy
Management (BOEM) produced a
Programmatic Environmental Impact
Statement (PEIS) to evaluate potential
significant environmental effects of
geological and geophysical (G&G)
activities on the Mid- and South
Atlantic Outer Continental Shelf (OCS),
pursuant to requirements of the
National Environmental Policy Act
(NEPA). BOEM’s PEIS and associated
Record of Decision are available online
at: www.boem.gov/Atlantic-G-G-PEIS/.
G&G activities include geophysical
surveys in support of hydrocarbon
exploration, as are planned by the five
IHA applicants discussed herein.
In 2014–15, we received multiple
separate requests for authorization for
take of marine mammals incidental to
geophysical surveys in support of
hydrocarbon exploration in the Atlantic
Ocean. The applicants are companies
that provide services, such as
geophysical data acquisition, to the oil
and gas industry. Upon review of these
requests, we submitted questions,
comments, and requests for additional
information to the individual applicant
companies. As a result of these
interactions, the applicant companies
provided revised versions of the
applications that we determined were
adequate and complete. Adequate and
complete applications were received
from ION GeoVentures (ION) on June
24, 2015, Spectrum Geo Inc. (Spectrum)
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on July 6, 2015, and from TGS–NOPEC
Geophysical Company (TGS) on July 21,
2015.
We subsequently posted these
applications for public review and
sought public input (80 FR 45195; July
29, 2015). The comments and
information received during this public
review period informed development of
the proposed IHAs (82 FR 26244; June
6, 2017), and all letters received are
available online at
www.fisheries.noaa.gov/action/
incidental-take-authorization-oil-andgas-industry-geophysical-surveyactivity-atlantic. Following conclusion
of this opportunity for public review,
we received revised applications from
Spectrum on September 18, 2015, and
from TGS on February 10, 2016. We
received additional information from
ION on February 29, 2016. We also
received adequate and complete
applications from two additional
applicants: WesternGeco, LLC (Western)
on February 17, 2016, and CGG on May
26, 2016. Full details regarding these
timelines were described in our Federal
Register Notice of Proposed IHAs (82 FR
26244; June 6, 2017).
On June 26, 2018, Spectrum notified
NMFS of a modification to their survey
plan. Spectrum’s letter and related
information is available online, as is
their preceding adequate and complete
application. The descriptions and
analyses contained herein were
complete at the time we received
notification of the modification.
Therefore, we present those descriptions
and analyses, including those related to
Spectrum’s request (as detailed in their
2015 application), intact as originally
developed. However, we provide detail
regarding Spectrum’s modified survey
plan, our evaluation of the modification
to the specified activity, and our finding
that the determinations made in regard
to Spectrum’s previously proposed
specified activity remain appropriate
and valid in a standalone section
entitled ‘‘Spectrum Survey Plan
Modification’’ at the end of this notice.
All issued authorizations are valid for
the statutory maximum of one year. All
applicants plan to conduct twodimensional (2D) marine seismic
surveys using airgun arrays. Generally
speaking, these surveys may occur
within the U.S. Exclusive Economic
Zone (EEZ) (i.e., to 200 nautical miles
(nmi)) from Delaware to approximately
Cape Canaveral, Florida, and
corresponding with BOEM’s Mid- and
South Atlantic OCS planning areas, as
well as additional waters out to 350 nmi
from shore. Please see the applications
for specific details of survey design. The
use of airgun arrays is expected to
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produce underwater sound at levels that
have the potential to result in
harassment of marine mammals.
Multiple cetacean species with the
expected potential to be present during
all or a portion of the planned surveys
are described below.
Because the specified activity,
specific geographic region, and planned
dates of activity are substantially similar
for the five separate requests for
authorization, we have determined it
appropriate to provide a joint notice for
issuance of the five authorizations.
However, while we provide relevant
information together, we consider the
potential impacts of the specified
activities independently and make
determinations specific to each request
for authorization, as required by the
MMPA.
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Description of the Specified Activities
In this section, we provide a
generalized discussion that is broadly
applicable to all five requests for
authorization, with project-specific
portions indicated.
Overview
The five applicants plan to conduct
deep penetration seismic surveys using
airgun arrays as an acoustic source.
Seismic surveys are one method of
obtaining geophysical data used to
characterize the subsurface structure, in
this case in support of hydrocarbon
exploration. The planned surveys are 2D
surveys, designed to acquire data over
large areas in order to screen for
potential hydrocarbon prospectivity. To
contrast, three-dimensional surveys may
use similar acoustic sources but are
designed to cover smaller areas with
greater resolution (e.g., with closer
survey line spacing). A deep penetration
survey uses an acoustic source suited to
provide data on geological formations
that may be thousands of meters (m)
beneath the seafloor, as compared with
a survey that may be intended to
evaluate shallow subsurface formations
or the seafloor itself (e.g., for hazards).
An airgun is a device used to emit
acoustic energy pulses into the seafloor,
and generally consists of a steel cylinder
that is charged with high-pressure air.
The firing pressure of an array is
typically 2,000 pounds per square inch
(psi). Release of the compressed air into
the water column generates a signal that
reflects (or refracts) off of the seafloor
and/or subsurface layers having acoustic
impedance contrast. When fired, a brief
(∼0.1 second (s)) pulse of sound is
emitted by all airguns nearly
simultaneously. The airguns do not fire
during the intervening periods, with the
array typically fired on a fixed distance
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(or shot point) interval. This interval
may vary depending on survey
objectives, but a typical interval for a 2D
survey in relatively deep water might be
25 m (approximately every 10 s,
depending on vessel speed). Vessel
speed when towing gear is typically 4–
5 knots (kn). The return signal is
recorded by a listening device and later
analyzed with computer interpretation
and mapping systems used to depict the
subsurface. In this case, towed streamers
contain hydrophones that would record
the return signal.
Individual airguns are available in
different volumetric sizes, and for deep
penetration seismic surveys are towed
in arrays (i.e., a certain number of
airguns of varying sizes in a certain
arrangement) designed according to a
given company’s method of data
acquisition, seismic target, and data
processing capabilities. A typical large
airgun array, as was considered in
BOEM’s PEIS (BOEM, 2014a), may have
a total volume of approximately 5,400
cubic inches (in3). The notional array
modeled by BOEM consists of 18
airguns in three identical strings of six
airguns each, with individual airguns
ranging in volume from 105–660 in3.
Sound levels for airgun arrays are
typically modeled or measured at some
distance from the source and a nominal
source level then back-calculated.
Because these arrays constitute a
distributed acoustic source rather than a
single point source (i.e., the ‘‘source’’ is
actually comprised of multiple sources
with some pre-determined spatial
arrangement), the highest sound levels
measurable at any location in the water
will be less than the nominal source
level. A common analogy is to an array
of light bulbs; at sufficient distance the
array will appear to be a single point
source of light but individual sources,
each with less intensity than that of the
whole, may be discerned at closer
distances. In addition, the effective
source level for sound propagating in
near-horizontal directions (i.e.,
directions likely to impact most marine
mammals in the vicinity of an array) is
likely to be substantially lower than the
nominal source level applicable to
downward propagation because of the
directional nature of the sound from the
airgun array. The horizontal propagation
of sound is reduced by noise
cancellation effects created when sound
from neighboring airguns on the same
horizontal plane partially cancel each
other out.
Survey protocols generally involve a
predetermined set of survey, or track,
lines. The seismic acquisition vessel
(source vessel) will travel down a linear
track for some distance until a line of
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data is acquired, then turn and acquire
data on a different track. In addition to
the line over which data acquisition is
desired, full-power operation may
include run-in and run-out. Run-in is
approximately 1 kilometer (km) of fullpower source operation before starting a
new line to ensure equipment is
functioning properly, and run-out is
additional full-power operation beyond
the conclusion of a trackline (typically
half the distance of the acquisition
streamer behind the source vessel) to
ensure that all data along the trackline
are collected by the streamer. Line turns
typically require two to three hours due
to the long, trailing streamers
(approximately 10 km). Spacing and
length of tracks vary by survey. Survey
operations often involve the source
vessel, supported by a chase vessel.
Chase vessels typically support the
source vessel by protecting the
hydrophone streamer from damage (e.g.,
from other vessels) and otherwise
lending logistical support (e.g.,
returning to port for fuel, supplies, or
any necessary personnel transfers).
Chase vessels do not deploy acoustic
sources for data acquisition purposes;
the only potential effects of the chase
vessels are those associated with normal
vessel operations.
Dates and Duration
All issued IHAs are valid for the
statutory maximum of one year from the
date of effectiveness. The IHAs are
effective upon written notification from
the applicant to NMFS, but not
beginning later than one year from the
date of issuance or extending beyond
two years from the date of issuance.
However, the expected temporal extent
of survey activity varies by company
and may be subject to unpredictability
due to inclement weather days,
equipment maintenance and/or repair,
transit to and from ports to survey
locations, and other contingencies.
Spectrum originally planned a 6-month
data acquisition program (February
through July), consisting of an expected
165 days of seismic operations. This
plan has been modified and now
consists of an estimated 108 days of
operations. Please see ‘‘Spectrum
Survey Plan Modification’’ for further
information. TGS plans a full year data
acquisition program, with an estimated
308 days of seismic operations. ION
plans a six-month data acquisition
program (July through December), with
an estimated 70 days of seismic data
collection. Western plans a full year
data acquisition program, with an
estimated 208 days of seismic
operations. CGG plans a six-month data
acquisition program (July through
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December), with an estimated 155 days
of seismic operations. Seismic
operations typically occur 24 hours per
day.
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Specific Geographic Region
The planned survey activities would
occur off the Atlantic coast of the
United States, within BOEM’s MidAtlantic and South Atlantic OCS
planning areas (i.e., from Delaware to
Cape Canaveral, FL), and out to 350 nmi
(648 km) (see Figure 1, reproduced from
BOEM, 2014a). The seaward limit of the
region is based on the maximum
constraint line for the extended
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continental shelf (ECS) under the
United Nations Convention on the Law
of the Sea. Until such time as an ECS
is established by the United States, the
region between the U.S. EEZ boundary
and the ECS maximum constraint line
(i.e., 200–350 nmi from shore) is part of
the global commons, and BOEM
determined it appropriate to include
this area within the area of interest for
geophysical survey activity.
The specific survey areas differ within
this region; please see maps provided in
the individual applications (Spectrum:
Figure 1; Western: Figures 1–1 to 1–4;
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TGS: Figures 1–1 to 1–4; ION: Figure 1;
CGG: Figure 3) (however, please see
‘‘Spectrum Survey Plan Modification’’
for further information). The specific
geographic region has not changed
compared with what was described in
our Notice of Proposed IHAs (82 FR
26244; June 6, 2017), nor has
substantive new information regarding
the region become available. Therefore,
we do not reprint that discussion here;
for additional detail regarding the
specific geographic region, please see
our Notice of Proposed IHAs.
BILLING CODE 3510–22–P
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BILLING CODE 3510–22–P
Detailed Description of Activities
Survey descriptions, as summarized
from specific applications, are provided
here. Please see Table 1 for a summary
of airgun array characteristics. With the
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exception of Spectrum, the planned
surveys have not changed from those
described in our Notice of Proposed
IHAs (82 FR 26244; June 6, 2017) Please
see ‘‘Spectrum Survey Plan
Modification’’ for further information.
For full detail, please see the individual
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IHA applications and our Notice of
Proposed IHAs. Note that all applicants
expect there to be limited additional
operations associated with equipment
testing, startup, line changes, and repeat
coverage of any areas where initial data
quality is sub-standard. Therefore, there
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Figure 1. Specific Geographic Region.
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could be some small amount of use of
the acoustic source not accounted for in
the total estimated line-km for each
survey; however, this activity is difficult
to quantify in advance and would
represent an insignificant increase in
effort.
ION—ION’s survey is planned to
occur from Delaware to northern Florida
(∼38.5° N to ∼27.9° N) (see Figure 1 of
ION’s application), and consists of
∼13,062 km of survey line. The acoustic
source planned for deployment is a 36airgun array with a total volume of
6,420 in3. The array would consist of
airguns ranging in volume from 40 in3
to 380 in3. The airguns would be
configured as four identical linear arrays
or ‘‘strings’’ (see Figure 3 of ION’s
application). The four airgun strings
would be towed at 10-m depth, and
would fire every 50 m or 20–24 s,
depending on exact vessel speed. ION
provided modeling results for their
array, including notional source
signatures, 1/3-octave band source
levels as a function of azimuth angle,
and received sound levels as a function
of distance and direction at 16
representative sites in the survey area.
For more detail, please see Figures 4–6
and Appendix A of ION’s application.
Spectrum—Spectrum’s survey was
originally planned to occur from
Delaware to northern Florida (see Figure
1 of Spectrum’s application), consisting
of ∼21,635 km of survey line. This plan
has been modified and now consists of
∼13,766 km of operations. Please see
‘‘Spectrum Survey Plan Modification’’
for further information). The acoustic
source planned for deployment is a 32airgun array with a total volume of
4,920 in3. The array would consist of
airguns ranging in volume from 50 in3
to 250 in3. The airguns would be
configured as four subarrays, each with
eight to ten airguns (see Figure 2 in
Appendix A of Spectrum’s application).
The four airgun strings would be towed
at 6 to 10-m depth, and would fire every
25 m or 10 s, depending on exact vessel
speed. Spectrum provided modeling
results for their array, including
notional source signatures, 1/3-octave
band source levels as a function of
azimuth angle, and received sound
levels as a function of distance and
direction at 16 representative sites in
the survey area. For more detail, please
see Appendix A of Spectrum’s
application.
As stated above, Spectrum notified
NMFS on June 26, 2018, of a
modification to their survey plan. Please
see ‘‘Spectrum Survey Plan
Modification’’ for further information.
TGS—TGS’s survey is planned to
occur from Delaware to northern Florida
(see Figure 1–1 of TGS’s application),
and consists of ∼58,300 km of survey
line. The survey plan consists of two
contiguous survey grids with differently
spaced lines (see Figures 1–1 to 1–4 of
TGS’s application), and would involve
use of two source vessels operating
independently of one another at a
minimum of 100 km separation
distance. The acoustic sources planned
for deployment are 40-airgun arrays
with a total volume of 4,808 in3. The
array would consist of airguns ranging
in volume from 22 in3 to 250 in3. The
airguns would be configured as four
identical strings (see Figure 3 in
Appendix B of TGS’s application). The
four airgun strings would be towed at 7m depth, and would fire every 25 m or
10 s, depending on exact vessel speed.
More detail regarding TGS’s acoustic
source and modeling related to TGS’s
application is provided in Appendix B
of TGS’s application.
Western—Western’s survey is planned
to occur from Maryland to northern
Florida (see Figure 1–1 of Western’s
application), and consists of ∼27,330 km
of survey line. The survey plan consists
of a survey grid with differently spaced
lines (see Figures 1–1 to 1–4 of
Western’s application). The acoustic
source planned for deployment is a 24airgun array with a total volume of
5,085 in3. The airguns would be
configured as three identical strings.
The three airgun strings would be towed
at 10-m depth, and would fire every
37.5 m (approximately every 16 s,
depending on vessel speed). More detail
regarding Western’s acoustic source and
modeling related to Western’s
application is provided in Appendix B
of Western’s application.
CGG—CGG’s survey is planned to
occur from Virginia to Georgia (see
Figure 3 of CGG’s application), and
consists of ∼28,670 km of survey line.
The acoustic source planned for
deployment is a 36-airgun array with a
total volume of 5,400 in3. The array
would consist of airguns ranging in
volume from 40 in3 to 380 in3. The
airguns would be configured as four
identical strings (see Figure 2 of CGG’s
application). The four airgun strings
would be towed at 7-m depth, and
would fire every 25 m or 10 s,
depending on exact vessel speed. More
detail regarding CGG’s acoustic source
and modeling related to CGG’s
application is provided in CGG’s
application.
TABLE 1—SURVEY AND AIRGUN ARRAY CHARACTERISTICS
Company
ION ............................................
Spectrum ...................................
TGS ...........................................
Western .....................................
CGG ..........................................
BOEM 2 ......................................
Total
planned
survey km
Total
volume
(in3)
13,062
13,766
58,300
27,330
28,670
n/a
Number of
guns
Nominal source output
(downward) 1
Number of
strings
0–pk
6,420
4,920
4,808
5,085
5,400
5,400
36
32
40
24
36
18
4
4
4
3
4
3
pk–pk
257
266
255
( 3)
( 3)
247
Shot interval
(m)
Tow depth
(m)
rms
263
272
( 3)
262
259
( 3)
4 247
243
240
235
3 4 243
233
50
25
25
37.5
25
n/a
10
6–10
7
10
7
6.5
1 See
‘‘Description of Active Acoustic Sound Sources,’’ later in this document, for discussion of these concepts.
array characteristics modeled and source characterization outputs from BOEM’s PEIS (2014a) provided for comparison.
3 Values not given; however, SPL (pk–pk) is usually considered to be approximately 6 dB higher than SPL (0–pk) (Greene, 1997).
4 Value decreased from modeled 0–pk value by minimum 10 dB (Greene, 1997).
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2 Notional
Comments and Responses
We published a Notice of Proposed
IHAs in the Federal Register on June 6,
2017 (82 FR 26244), beginning a 30-day
comment period. In that notice, we
requested public input on the requests
for authorization described therein, our
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analyses, the proposed authorizations,
and any other aspect of the Notice of
Proposed IHAs for the five separate
specified geophysical survey activities,
and requested that interested persons
submit relevant information,
suggestions, and comments. We further
specified that, in accordance with the
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requirements of the MMPA, we would
only consider comments that were
relevant to marine mammal species that
occur in U.S. waters of the Mid- and
South Atlantic and the potential effects
of the specified geophysical survey
activities on those species and their
habitat. We also noted that comments
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indicating general support for or
opposition to hydrocarbon exploration
or any comments relating to
hydrocarbon development (e.g., leasing,
drilling) were not relevant to the
proposed actions and would not be
considered. We requested that
comments indicate whether they were
general to all of the proposed
authorizations or specific to one or more
of the five separate proposed
authorizations, and that comments
should be supported by data or
literature citations as appropriate.
Following requests to extend the public
comment period, we determined it
appropriate to do so by an additional 15
days (82 FR 31048; July 5, 2017).
Including the 15-day extension, the
public comment period concluded on
July 21, 2017. Comments received after
the close of the comment period were
not considered.
During the 45-day comment period,
we received 117,294 total comment
letters. Of this total, we determined that
approximately 3,196 comment letters
represented unique submissions,
including 73 letters from various
organizations or individuals acting in an
official capacity (e.g., non-governmental
organizations, representatives and
members of the oil and gas industry,
state and local government, members of
Congress, members of academia) and
3,103 unique submissions from private
citizens. We note that the 73 letters
represent approximately 330
organizations or individuals, as many
letters included multiple co-signers. The
remaining approximately 114,118
comment letters followed one of 20
different generic template formats, in
which respondents provided comments
that were identical or substantively the
same. We consider each of the 20
different templates to represent a single
unique submission that is included in
the value cited above (3,196).
Separately, we received 15 petitions,
with a total of 99,423 signatures. Of
these, one petition (595 signatures)
expressed support for issuance of the
proposed IHAs, while the remainder
expressed opposition to issuance of the
proposed IHAs or, more generally, to oil
and gas exploration and/or development
in the U.S. Atlantic Ocean.
NMFS has reviewed all public
comments received on the proposed
issuance of the five IHAs. All relevant
comments and our responses are
described below. Comments indicating
general support for or opposition to
hydrocarbon exploration but not
containing relevant recommendations or
information are not addressed here.
Similarly, any comments relating to
hydrocarbon development (e.g., leasing,
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drilling)—including numerous
comments received that expressed
concern regarding the risks of oil spills
or of potential future industrialization
on the U.S. Atlantic coast—are not
relevant to the proposed actions and
therefore were not considered and are
not addressed here. We also provide no
response to specific comments that
addressed species or statutes not
relevant to our proposed actions under
section 101(a)(5)(D) of the MMPA (e.g.,
comments related to sea turtles), nor do
we respond to comments more
appropriately directed at BOEM
pursuant to their authority under the
Outer Continental Shelf Lands Act
(OCSLA) to permit the planned
activities. For those comments germane
to the proposed IHAs, we outline our
comment responses by major categories.
Recurring comments are noted below as
having been submitted by ‘‘several’’ or
‘‘many’’ commenters to avoid repetition.
The 73 letters from various
organizations or individuals acting in an
official capacity, and representatives of
each of the 20 form letter templates, are
available online at:
www.fisheries.noaa.gov/action/
incidental-take-authorization-oil-andgas-industry-geophysical-surveyactivity-atlantic. Remaining comments
are part of our administrative record for
these actions but are not available
online.
General Comments
A large majority of commenters,
including all of those following one of
the 20 templates, expressed general
opposition towards geophysical airgun
surveys in the U.S. Atlantic Ocean. We
reiterate here that NMFS’s proposed
actions concern only the authorization
of marine mammal take incidental to the
planned surveys—jurisdiction
concerning decisions to allow the
surveys rests solely with BOEM,
pursuant to their authority under the
OCSLA. Further, NMFS does not have
discretion regarding issuance of
requested incidental take authorizations
pursuant to the MMPA, assuming (1) the
total taking associated with a specified
activity will have a negligible impact on
the affected species or stock(s); (2) the
total taking associated with a specified
activity will not have an unmitigable
adverse impact on the availability of the
species or stock(s) for subsistence uses
(not relevant here); (3) the total taking
associated with a specified activity is
small numbers of marine mammals of
any species or stock; and (4) appropriate
mitigation, monitoring, and reporting of
such takings are set forth, including
mitigation measures sufficient to meet
the standard of least practicable adverse
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impact on the affected species or stocks.
A large volume of the comments
received request that NMFS not issue
any of the IHAs and/or express disdain
for NMFS’s proposal to issue the
requested IHAs, but without providing
information relevant to NMFS’s
decisions. These comments appear to
indicate a lack of understanding of the
MMPA’s requirement that NMFS shall
issue requested authorizations when the
above listed conditions are met;
therefore, these comments were not
considered.
In general, commenters described the
close linkages between their local and
state economies to a healthy ocean,
contending that the planned surveys
could have substantial impacts on, for
example, commercial and recreational
fishing, wildlife viewing, outdoor
recreation, and businesses dependent on
these activities. Commenters suggested
that NMFS should undertake analyses
unrelated to the proposed actions (i.e.,
issuance of requested IHAs), such as a
cost-benefit analysis of hydrocarbon
exploration and development compared
to the economic benefits of coastal
tourism and healthy fisheries. Many
commenters also noted that over 120
municipalities and cities and 1,200
elected officials on the Atlantic coast
have passed resolutions or otherwise
formally opposed hydrocarbon
exploration and/or development in the
region. We also received comments
expressing general opposition to oil and
gas exploration activity from the
Business Alliance for Protecting the
Atlantic Coast, which stated that the
comments were submitted on behalf of
41,000 businesses and 500,000
commercial fishing families. While
NMFS recognizes the overwhelming
opposition expressed by the public to
oil and gas exploration and/or
development in the U.S. Atlantic Ocean
that it has received, we remain
appropriately focused on consideration
of the best available scientific
information in support of our analyses
pursuant to the MMPA, specific to the
five IHAs considered herein.
Multiple commenters focused on
specific, rather than general, issues that
are not germane to our consideration of
requested action under the MMPA. For
example, the Northwest Atlantic Marine
Alliance (NAMA) and other groups
provided comments related to potential
impacts on commercial fisheries, and
the New Jersey Council of Diving Clubs
expressed concern regarding potential
impacts of the planned surveys on
recreational divers. Recommendations
were provided concerning mitigating
potential impacts. We reiterate that
NMFS’s proposed action—the issuance
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of IHAs authorizing incidental take of
marine mammals—necessarily results in
impacts only to marine mammals and
marine mammal habitat. Effects of the
surveys more broadly are the purview of
BOEM, which has jurisdiction under
OCSLA for permitting the actual
surveys, as opposed to authorizing take
of marine mammals incidental to a
permitted survey. Therefore, we do not
address comments such as these.
Multiple groups stated that NMFS
should consider impacts and protection
for other species in the action area, such
as Atlantic sturgeon, other fish species,
invertebrates, plankton, and sea turtles.
Some of these comments specifically
referenced the importance of the area
offshore Cape Hatteras as home to a
diverse assemblage of non-marine
mammal species, including sharks,
turtles, seabirds, and other fish species.
The NAMA provided comments relating
to Essential Fish Habitat (EFH) (as
designated pursuant to the Magnuson
Stevens Fishery Conservation and
Management Act (MSA), as amended by
the Sustainable Fisheries Act of 1996
(Pub. L. 104–267)), including concerns
regarding effects to EFH resulting from
the planned surveys. Because NMFS’s
proposed action is limited to the
authorization of marine mammal take
incidental to the planned surveys,
effects of the surveys on aspects of the
marine environment other than marine
mammals and their habitat are not
relevant to NMFS’s analyses under the
MMPA. Pursuant to guidance from
NMFS’s Office of Habitat Conservation
concerning EFH and MMPA incidental
take authorizations, we have determined
that the issuance of these IHAs will not
result in adverse impacts to EFH, and
further, that issuance of these IHAs does
not require separate consultation per
section 305(B)(2) of the MSA. We do not
further address potential impacts to
EFH.
The MMPA does require that we
evaluate potential effects to marine
mammal habitat, which includes prey
species (e.g., zooplankton, fish, squid).
However, consideration of potential
effects to taxa other than marine
mammals and their prey, or
consideration of effects to potential prey
species in a context other than the
import of such effects on marine
mammals, is not relevant to our action
under the MMPA. We have
appropriately considered effects to
marine mammal habitat. Separately,
BOEM evaluated effects to all relevant
aspects of the human environment
(including marine mammals and other
taxa) through the analysis presented in
their PEIS (available online at:
www.boem.gov/Atlantic-G-G-PEIS/), and
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effects to all potentially affected species
that are listed under the Endangered
Species Act (ESA) and any critical
habitat designated for those species
were addressed through consultation
between BOEM and NMFS pursuant to
section 7 of the ESA. That Biological
Opinion, which evaluated both BOEM’s
(issuing permits for the five surveys)
and NMFS’s (issuing IHAs associated
with the five permitted surveys)
proposed actions, is available online at:
www.fisheries.noaa.gov/action/
incidental-take-authorization-oil-andgas-industry-geophysical-surveyactivity-atlantic. We do not further
address taxa other than marine
mammals and marine mammal prey.
Marine Mammal Impacts
Comment: Many commenters
expressed concern regarding the
perceived lack of information regarding
the affected marine mammal stocks and
the impacts of the surveys on marine
mammal individuals and populations
and their habitat (direct and indirect;
short- and long-term).
Response: NMFS acknowledges that,
while there is a growing body of
literature on the affected marine
mammal stocks and regarding the
impacts of noise on individual marine
mammals, data gaps do remain,
particularly with regard to potential
population-level impacts and
cumulative impacts. However, NMFS
must use the best available scientific
information in analyses supporting its
determinations pursuant to the MMPA,
and has done so here. While NMFS does
not take lightly the potential effects of
surveys on marine mammal
populations, these surveys, with the
robust suite of required mitigation and
monitoring, are expected to have a
negligible impact on the affected species
and stocks.
Comment: Many commenters
expressed general concern regarding
impacts to both individual marine
mammals and potential populationlevel harm, including impacts to
important behaviors and chronic stress
stemming from acoustic disturbance.
More specifically, this included:
Potential displacement from preferred
feeding, breeding, and migratory
habitats, which could lead to long-term
and large-scale habitat avoidance or
abandonment; impacts to mating,
vocalizing, and other key marine
mammal behaviors; communication
interference between cow-calf pairs,
which could lead to stranding increases
and juvenile deaths; hearing loss
hindering recruitment and marine
mammals’ ability to locate mates and
find food.
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Response: NMFS has carefully
reviewed the best available scientific
information in assessing impacts to
marine mammals, and recognizes that
the surveys have the potential to impact
marine mammals through threshold
shifts, behavioral effects, stress
responses, and auditory masking.
However, NMFS has determined that
the nature of such potentially transitory
exposure—any given location will be
exposed to survey noise only relatively
briefly and infrequently—means that the
potential significance of the authorized
taking, including potential long-term
avoidance, is limited. NMFS has also
prescribed a robust suite of mitigation
measures, such as time-area restrictions
and extended distance shutdowns for
certain species, that are expected to
further reduce the duration and
intensity of acoustic exposure, while
limiting the potential severity of any
possible behavioral disruption.
Comment: Many commenters
described impacts to ‘‘millions of
marine mammals,’’ expressing concern
that NMFS would allow such a level of
impacts, or stating concern that NMFS
would allow killing of marine
mammals. Similarly, many commenters
refer to taking or killing ‘‘138,000
marine mammals.’’
Response: Many of these comments
were written with reference to the
acoustic exposure analysis provided in
BOEM’s PEIS, which is not directly
related to the specific surveys that are
the subject of NMFS’s analysis. In fact,
the more specific figure commonly cited
(i.e., 138,000) represents the number of
incidents of Level A harassment
estimated by BOEM in their analysis
using now-outdated guidance (i.e., 180dB root mean square (rms) with no
consideration of frequency sensitivity)
that the best available science indicates
does not reflect when Level A
harassment should be expected to occur.
Certain non-governmental organizations
have incorrectly suggested the
information represents animals killed.
In addition, BOEM’s programmatic
analysis was based on a vastly greater
amount of survey activity occurring per
year over a period of nine years, versus
the five surveys considered herein.
Regardless, NMFS cannot issue the
authorizations unless the total taking
expected to occur as a result of each
specified activity is determined to result
in a negligible impact to the affected
species or stocks. The best available
science indicates that Level B
harassment, or disruption of behavioral
patterns, is likely to occur, and that a
limited amount of auditory injury, or
permanent threshold shift (PTS) (Level
A harassment) may occur for a few
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species. No mortality is expected to
occur as a result of the planned surveys,
and there is no scientific evidence
indicating that any marine mammal
could experience mortality as a direct
result of noise from geophysical survey
activity. Authorization of mortality may
not occur via IHAs, and such
authorization was neither requested nor
proposed. Finally, we emphasize that an
estimate of take numbers alone is not
sufficient to assess impacts to a marine
mammal population. Take numbers
must be viewed contextually with other
factors, as explained in the ‘‘Negligible
Impact Analyses and Determinations’’
section of this Notice.
Comment: Several commenters
referenced studies showing that noise
from airgun surveys can travel great
distances underwater, leading to
concern that the surveys would impact
marine mammals throughout the
specific geographic region at all times.
Some commenters then suggested that
this would result in there being no
available habitat for displaced animals
to escape to.
Response: NMFS acknowledges that
relatively loud, low-frequency noise (as
is produced by airgun arrays) has the
potential to propagate across large
distances. However, propagation and
received sound levels are highly
variable based on many biological and
environmental factors. For example,
while one commonly cited study
(Nieukirk et al., 2012) described
detection of airgun sounds almost 4,000
km from the acoustic source, the sensors
were located within the deep sound
channel (SOFAR), where low-frequency
signals may travel great distances due to
the advantageous propagation
environment. While sounds within this
channel are unlikely to be heard by
most marine mammals due to the depth
of the SOFAR channel—which is
dependent primarily on temperature
and water pressure and therefore
variable with latitude—it is arguable
whether sounds that travel such
distances may be heard by whales as a
result of refraction to shallower depths
(Nieukirk et al., 2012; McDonald et al.,
1995). Regardless, while the extreme
propagation distances cited in some
comments may not be realistic in terms
of effects on mysticetes, we
acknowledge that contraction of
effective communication space for
whales that vocalize and hear at
frequencies overlapping those emitted
by airgun arrays can occur at distances
on the order of tens to hundreds of
kilometers. However, attenuation to
levels below the behavioral harassment
criterion (i.e., 160 dB rms) will likely
always occur over much shorter
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distances and, therefore, we do not
agree with the contention that
essentially the entire specific geographic
region would be ensonified to a degree
that marine mammals would find it
unsuitable habitat. Rather, it is likely
that displacement would occur within a
much smaller region in the vicinity of
the acoustic source (e.g., within 5–10
km of the source, depending on season
and location). Overall, the specific
geographic region and marine mammal
use of the area is sufficiently large that,
although displacement may occur, the
region offers enough habitat for marine
mammals to seek temporary viable
habitat elsewhere, if necessary. Many of
the affected species occupy a wide
portion of the region, and it is expected
that individuals of these species can
reasonably find temporary foraging
grounds or other suitable habitat areas
consistent with their natural use of the
region. Further, although the planned
surveys would cover large portions of
the U.S. Mid- and South Atlantic, they
will only be transitory in any given area.
Therefore, NMFS does not expect
displacement to occur frequently or for
long durations. Importantly, for species
that show high site fidelity to a
particular area (e.g., pilot whales around
Cape Hatteras) or to bathymetric
features (e.g., sperm whales and beaked
whales), NMFS has required additional
time-area restrictions to reasonably
minimize these impacts.
Comment: The Bald Head Island
Association commented that many
bottlenose dolphin populations are
depleted, and risks from the surveys are
too great.
Response: NMFS acknowledges that
coastal bottlenose dolphin stocks are
depleted under the MMPA, and we
described the 2013–2015 Unusual
Mortality Event affecting these stocks in
our Notice of Proposed IHAs. NMFS is
requiring a year-round closure to all
survey activity out to 30 km offshore,
including a 20-km distance beyond
which encountered dolphins would
generally be expected to be of the
offshore stock and a 10-km buffer
distance that is expected to encompass
all received sound levels exceeding the
160-dB rms Level B harassment
criterion. In consideration of this
mitigation requirement, NMFS believes
that impacts to coastal bottlenose
dolphins will be minimal.
Comment: The New York State
Department of Environmental
Conservation expressed concern about
impacts from the surveys to animals in
the New York Bight, noting that even
though the surveys would not be
occurring in the vicinity of New York
Bight many of the same animals that use
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the New York Bight for certain life
history strategies would also be found in
certain times of year in the specific
geographic region.
Response: Although unrelated to our
analyses and necessary findings
pursuant to the MMPA, we note that in
requesting the opportunity to conduct
review of the proposed surveys
pursuant to the Coastal Zone
Management Act, New York did not
demonstrate that the surveys would
have reasonably foreseeable effects on
New York’s coastal uses or resources.
Therefore, New York’s request was
denied. However, we acknowledge that
some of the same animals that may
occur in the New York Bight could also
occur at other times of year within the
survey region and, therefore, be affected
by the specified activities. However, as
detailed elsewhere in this document, we
have found for each specified activity
and each potentially affected species or
stock that the taking would have a
negligible impact.
Comment: The Natural Resources
Defense Council (NRDC) submitted
comments on behalf of itself and over
thirty other organizations, including the
Center for Biological Diversity,
Defenders of Wildlife, Earthjustice, The
Humane Society of the United States,
Sierra Club, et al. Hereafter, we refer to
this collective letter as ‘‘NRDC.’’ NRDC
and other commenters assert that the
surveys will drive marine mammals into
shipping lanes, thereby increasing their
risk of ship strike.
Response: As an initial matter, we
address overall themes in NRDC’s 85page comment letter. In addition to
mischaracterizing the literature, likely
impacts to marine mammals, and
NMFS’s analyses in multiple places—
which we attempt to correct throughout
our responses—the letter repeatedly
makes use of undefended or off-point
assertions (e.g., that NMFS’s findings
are ‘‘arbitrary and capricious’’ and
‘‘non-conservative’’). While we have
attempted to clarify and correct
individual mischaracterizations in our
specific responses to comments, we
broadly address the issue here. NRDC’s
16 assertions that NMFS’s analyses and/
or conclusions are ‘‘arbitrary and
capricious’’ or just ‘‘arbitrary’’ are
unfounded. Similarly, NRDC claims that
NMFS’s approaches or decisions are
‘‘non-conservative,’’ or should be more
‘‘conservative,’’ at least 15 times, with
no indication of what standard they are
seeking to attain. While NRDC may
disagree with the issuance of the IHAs
or the underlying activities themselves,
we believe the administrative record for
these IHAs amply demonstrates that
NMFS used the best available science
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during our administrative process to
inform our analyses and satisfy the
standards under section 101(a)(5)(D).
With regard to this specific comment,
the surveys are largely not occurring in
or near any shipping lanes, as they will
occur a minimum of 30 km offshore.
NMFS is not aware of any scientific
information suggesting that the surveys
would drive marine mammals into
shipping lanes, and disagrees that this
would be a reasonably anticipated effect
of the specified activities.
Comment: Comments submitted
jointly by Oceana and the International
Fund for Animal Welfare (hereafter,
‘‘Oceana’’) and, separately, by Sea
Shepherd Legal discuss particular
concerns regarding potential impacts to
large whales. The comments cite studies
showing modified singing behavior and
habitat avoidance among fin whales in
response to airguns; that sperm whales
in the Gulf of Mexico have shown
decreased buzz rates around airguns;
that singing among humpback whales
declined in response to airgun noise;
etc.
Response: NMFS reviewed all cited
studies in making its determinations for
both the proposed and final IHAs, and
agrees that there are multiple studies
documenting changes in behavior and/
or communication amongst large whales
in response to airgun noise, sometimes
at significant distance. Changes in
vocalization associated with exposure to
airgun surveys within migratory and
non-migratory contexts have been
observed (e.g., Castellote et al., 2012;
Blackwell et al., 2013; Cerchio et al.,
2014). The potential for anthropogenic
sound to have impacts over large spatial
scales is not surprising for species with
large communication spaces, like
mysticetes (e.g., Clark et al., 2009);
however, not every change in a
vocalization would necessarily rise to
the level of a take, much less have
meaningful consequences to the
individual or for the affected
population. As noted previously, the
planned surveys are expected to be
transient and would not result in any
sustained impacts to such behaviors for
baleen whales. We also acknowledge
that exposure to noise from airguns may
impact sperm whale foraging behavior
(Miller et al., 2009). However, our
required mitigation—including timearea restrictions designed to protect
certain habitat expected to be of
importance for foraging sperm whales,
in addition to standard shutdown
requirements expected to minimize the
severity and duration of any
disturbance—when considered in
context of the transient nature of the
impacts possible for these surveys lead
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us to conclude that effects to large
whales will be no greater than a
negligible impact and will be mitigated
to the level of least practicable adverse
impact.
Comment: Several industry
commenters stated, in summary, that
there is no scientific evidence that
geophysical survey activities have
caused adverse consequences to marine
mammal stocks or populations, and that
there are no known instances of injury
to individual marine mammals as a
result of such surveys, stating that
similar surveys have been occurring for
years without significant impacts. One
stated that surveys have been ongoing in
the Gulf of Mexico for years and have
not resulted in any negative impacts to
marine mammals, including reducing
fitness in individuals or populations.
Referring to other regions, the
commenters stated that bowhead whale
numbers have increased in the Arctic
despite survey activity. CGG noted that
there is no ‘‘empirical evidence’’ of
surveys causing injury or mortality to
marine mammals, and that previous
surveys resulted in less take than
authorized. Another group added that
BOEM has spent $50 million on
protected species and noise research
over four decades with no evidence of
adverse effects.
Response: Disruption of behavioral
patterns (i.e., Level B harassment) has
been documented numerous times for
marine mammals in the presence of
airguns (in the form of avoidance of
areas, notable changes in vocalization or
movement patterns, or other shifts in
important behaviors; see ‘‘Potential
Effects of the Specified Activity on
Marine Mammals and Their Habitat’’).
Further, lack of evidence for a
proposition does not prove it is false. In
this case, there is growing scientific
evidence demonstrating the connections
between sub-lethal effects, such as
behavioral disturbance, and populationlevel effects on marine mammals (e.g.,
Lusseau and Bedjer, 2007; New et al.,
2014). Disruptions of important
behaviors, in certain contexts and
scales, have been shown to have
energetic effects that can translate to
reduced survivorship or reproductive
rates of individuals (e.g., feeding is
interrupted, so growth, survivorship, or
ability to bring young to term is
compromised), which in turn can
adversely affect populations depending
on their health, abundance, and growth
trends.
Based on the available evidence, a
responsible analysis of potential
impacts of airgun noise on marine
mammal individuals and populations
cannot assume that such effects cannot
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occur. In reality, conclusive statements
regarding population-level
consequences of acoustic stressors
cannot be made due to insufficient
investigation, as such studies are
exceedingly difficult to carry out and no
appropriate study and reference
populations have yet been established.
For example, a recent report from the
National Academy of Sciences noted
that, while a commonly-cited statement
from the National Research Council
(‘‘[n]o scientific studies have
conclusively demonstrated a link
between exposure to sound and adverse
effects on a marine mammal
population’’) remains true, it is largely
because such impacts are very difficult
to demonstrate (NRC, 2005; NAS, 2017).
Population-level effects are inherently
difficult to assess because of high
variability, migrations, and multiple
factors affecting the populations.
However, NMFS has carefully
considered the available evidence in
determining the most appropriate suite
of mitigation measures and in making
the necessary determinations (see
‘‘Negligible Impact Analyses and
Determinations’’).
Comment: NRDC states that NMFS
must consider that behavioral
disturbance can amount to Level A
harassment, or to serious injury or
mortality, if it interferes with essential
life functions through secondary effects,
stating that displacement from
migration paths can result in heightened
risk of ship strike or predation,
especially for right whales. In a similar
vein, Oceana expressed concern about
the presence of additional ships in the
Atlantic, risking serious injury to
marine mammals from ship strike or
entanglement. Relatedly, NRDC noted
that NMFS’s conclusion that ship strikes
will not occur indicates an assumption
that required ship-strike avoidance
procedures will be effective. NRDC
disagrees that the ship-strike avoidance
measures will be effective.
Response: NMFS acknowledges that
sufficient disruption of behavioral
patterns could theoretically, likely in
connection with other stressors, result
in a reduction in fitness and ultimately
injury or mortality. However, such an
outcome could likely result only from
repeated disruption of important
behaviors at critical junctures, or
sustained displacement from important
habitat with no associated
compensatory ability. No such outcome
is expected as a result of these surveys,
which will be transient in any given
area within the large overall region, and
which avoid some of the most important
habitat. Effects such as those suggested
by NRDC would not be expected for
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right whales, as the surveys are required
to avoid migratory pathways (80 km
from coast), or achieve comparable
protection provided through
implementation of a NMFS-approved
mitigation and monitoring plan at
distances between 47–80 km offshore
(see ‘‘Mitigation’’ for more information).
Although the primary stressor to
marine mammals from the specified
activities is acoustic exposure to the
sound source, NMFS takes seriously the
risk of vessel strike and has prescribed
measures sufficient to avoid the
potential for ship strike to the extent
practicable. NMFS has required these
measures despite a very low likelihood
of vessel strike; vessels associated with
the surveys will add a discountable
amount of vessel traffic to the specific
geographic region (i.e., each survey will
operate with roughly 2–3 vessels) and,
furthermore, vessels towing survey gear
travel at very slow speeds (i.e., roughly
4–5 kn).
NMFS’s required vessel strike
avoidance protocol is expected to
further minimize any potential
interactions between marine mammals
and survey vessels. Please see ‘‘Vessel
Strike Avoidance’’ for a full description
of requirements, which include: Vessels
must maintain a 10 kn speed restriction
when in North Atlantic right whale
critical habitat, Seasonal Management
Areas, or Dynamic Management Areas;
vessel operators and crews must
maintain a vigilant watch for all marine
mammals and must take necessary
actions to avoid striking a marine
mammal; vessels must reduce speeds to
10 kn or less when mother/calf pairs,
pods, or large assemblages of cetaceans
are observed near a vessel; and vessels
must maintain minimum separation
distances.
Comment: NRDC stated that NMFS
did not properly consider potential
impacts of masking to marine mammals.
For example, NRDC notes that NMFS
addresses masking in the general
consequences discussion of its
negligible impact analysis, but disagrees
with NMFS’s conclusion that
consequences are appropriately
categorized as ‘‘medium’’ rather than
‘‘high’’ for mysticetes, citing the
distances at which vocal modifications
to distant sounds have been detected in
low-frequency cetaceans and newlydescribed low-level communication
calls between humpback whales and
their calves, which they suggest have
dire implications for right whales.
NRDC also states that NMFS incorrectly
thinks masking is co-extensive with the
modeled 160-dB rms behavioral
harassment zones, and suggests that
NMFS should take a modeling approach
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to better assess potential masking.
Relatedly, another commenter stated a
belief that NMFS assumes that there is
no potential for masking during the
interpulse interval, when in fact there is
noise during that period due to
multipath arrivals.
Response: NMFS disagrees that the
potential impacts of masking were not
properly considered. NMFS
acknowledges our understanding of the
literature NRDC cites regarding the
greater sensitivity of low-frequency
cetaceans to airgun survey noise via the
designation of these effects as
‘‘medium,’’ but fundamentally, the
masking effects to any one individual
whale from one survey operating far
offshore are expected to be minimal.
Masking is referred to as a chronic effect
because one of the key harmful
components of masking is its duration—
the fact that an animal would have
reduced ability to hear or interpret
critical cues becomes much more likely
to cause a problem the longer it is
occurring. Also, inherent in the concept
of masking is the fact that the potential
for the effect is only present during the
times that the animal and the source are
in close enough proximity for the effect
to occur (and further this time period
would need to coincide with a time that
the animal was utilizing sounds at the
masked frequency) and, as our analysis
(both quantitative and qualitative
components) indicates, because of the
relative movement of whales and
vessels, we do not expect these
exposures with the potential for
masking to be of a long duration within
a given day. Further, because of the
relatively low density of mysticetes, the
time-area restrictions, and large area
over which the vessels travel, we do not
expect any individual whales to be
exposed to potentially masking levels
from these surveys more than a few days
in a year.
NMFS recognizes that masking may
occur beyond the 160-dB zone and,
further, that the primary concern is
when numerous sources, many of which
may be at distances beyond their 160-dB
isopleth, contribute to higher
background noise levels over extended
time periods and significant portions of
an individual’s acoustic habitat.
However, as noted above, any masking
effects of these single surveys operating
far offshore (with no expectation that
any of the five would be in close enough
proximity to one another to
contemporaneously expose animals to
noise from multiple source vessels) are
expected to be limited and brief, if
present. Further, we recognize the
presence of multipath arrivals,
especially the farther the receiver is
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from the ship, but given the reduced
received levels at distance, combined
with the short duration of potential
masking and the lower likelihood of
extensive additional contributors to
background noise this far offshore and
within these short exposure periods, we
believe that the incremental addition of
the seismic vessel is unlikely to result
in more than minor and short-term
masking effects, likely occurring to
some small number of the same
individuals captured in the estimate of
behavioral harassment.
In regard to some of the specific
examples NRDC raised, we acknowledge
that vocal modifications of lowfrequency cetaceans in response to
distant sound sources have been
detected. However, as discussed
elsewhere in this Notice, not every
behavioral change or minor vocal
modification rises to the level of a take
or has any potential to adversely impact
marine mammal fitness, and NRDC has
not demonstrated why it believes the
short duration exposures that lowfrequency cetaceans might be exposed
to a few times a year from a survey
should constitute a ‘‘high’’ versus
‘‘medium’’ consequence in NMFS’s
assessment framework.
Similarly, NMFS is also aware of the
Videsen et al. (2017) paper reporting the
lower-level communication calls
between humpback mother-calf pairs
and noting the increased risk of cow-calf
separation with increases in background
noise. We first note that only neonates
were tagged and measured in this study
(i.e., circumstances could change with
older calves). Further, while
vocalizations between these pairs are
comparatively lower level than between
adults, the cow and neonate calf are in
regular close proximity (as evidenced by
the extent of measured sound generated
by rubbing in this study), which means
that the received levels for cow-calf
communication are higher than they
would be if the animals were separated
by the distance typical between adults—
in other words, it is unclear whether
these lower-level, but close proximity,
communications are comparatively
more susceptible to masking. Assuming
that right whale cow-calf pairs use the
same lower-level communication calls,
we first note that across all five surveys,
modeled results estimate that 19 right
whales may intercept with the
tracklines of the surveys such that they
are potentially taken and, further, as
described in the ‘‘Negligible Impact
Analyses and Determinations’’ section
and based on available demographic
information, it should be expected that
no more than four exposures could be
of adult females with calves (not
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specifically neonates). Again, when this
very low likelihood of encountering
cow-calf pairs is combined with the fact
that any individuals (or cow-calf pairs)
would not be expected to be exposed on
more than a couple/few days in a year,
NRDC has not demonstrated how the
consequences of these activities would
be ‘‘catastrophic,’’ for right whales, and
we believe our analysis supports a
‘‘medium’’ consequence rating.
Last, in response to the suggestion
that we utilize a model, such as the
model NMFS used for assessing similar
potential impacts in the Gulf of Mexico,
to assess impacts to communication
space from the surveys evaluated here—
it is neither necessary nor an
appropriate use of those tools. As noted
above, the combination of the modeled
take estimates, along with a qualitative
evaluation of the temporal and spatial
footprint of the activities within the
large action area and dispersed marine
mammal distributions, makes it clear
that masking effects, if any, would be
highly limited for these activities. In the
Gulf of Mexico, NMFS used the
referenced model in the context of a
five-year rule to programmatically
assess the chronic impacts of an entire
seismic program in a mature and active
hydrocarbon-producing region, with a
significantly greater amount of effort
than is contemplated in these five
surveys, overlaid in an area with already
otherwise high ambient noise. Use of
the model is comparatively expensive
and time-consuming, and produces a
relatively gross-scale comparison of
predicted annual averages (or other
duration) of accumulated sound energy
(which can also be interpreted in the
context of the communication space of
any species). This sort of analysis can be
helpful in understanding relative
chronic effects when higher and longerterm overall levels of activity and
impacts are being evaluated across areas
with notably variable levels of activities
and/or ambient noise, and can
potentially inform decisions regarding
time-area mitigation. Here, however,
any impacts to communication space
from any individual survey are expected
to be minimal; in addition to being
unnecessary, the lack of granularity in
the suggested model (which is
appropriate at larger and denser scales
of impacts, and which can be improved
with improvement of the available input
data) is such that its application to these
activities would not produce useful
information.
Comment: The South Carolina
Environmental Law Project, on behalf of
the Business Alliance for Protecting the
Atlantic Coast, commented that chronic
stress is possible from the specified
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activities and that likely stress effects
would be exacerbated due to their
contention that avoidance is impossible.
Response: As described in our Notice
of Proposed IHAs, NMFS recognizes
that stress from acoustic exposure is one
potential impact of these surveys, and
that chronic stress can have fitness,
reproductive, etc. impacts at the
population-level scale. However, we
believe the possibility for chronic stress
is low given the transitory and
intermittent nature of the sound source
(i.e., acoustic exposure in specific areas
will not be long lasting). The potential
for chronic stress was evaluated in
making the determinations presented in
NMFS’s negligible impact analyses.
Comment: An individual stated that
NMFS did not account for long-term
impacts to species, writing that it is
impossible to accurately account for
impacts without looking at the effects of
sound disturbance on energy balance
(e.g., when disturbance results in
additional time spent traveling and/or
foraging in less optimal habitats, the
result may be a negative energy
balance). The commenter stated further
that this negative energy balance could
have effects both individually and
cumulatively for a population, and that
the cumulative effect of behavioral
disturbance could be equivalent to a
certain amount of lethal takes.
Response: NMFS acknowledges that
the concerns raised are theoretically
possible, but in this case, with limited
duration of individual surveys or of
overlap of multiple surveys, and
modeled take estimates suggesting that
individuals would rarely be impacted
by any given survey more than a few
days in a year, frequent and long-term
displacement is not expected. Therefore,
NMFS does not anticipate behavioral
disruptions sufficient to negatively
impact individual energy balances,
much less to a degree where long-term
effects resulting in impacts to
recruitment or survival would occur.
For example, while the available
evidence indicates sensitivity to
disruption of foraging efficiency for
sperm whales exposed to airgun noise
(Miller et al., 2009), a recent
bioenergetic modeling exercise showed
that infrequent, minor disruptions in
foraging—as are expected in this case—
are unlikely to be fatal (Farmer et al.,
2018). The authors conclude that
foraging disruptions would have to be
relatively frequent to lead to terminal
starvation, but continual minor
disruptions can cause substantial
reductions in available reserves. Given
the temporary, infrequent nature of
exposure likely to result from the
planned surveys, in conjunction with
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the planned mitigation, which includes
effort restrictions in areas expected to be
of importance for sperm whale foraging,
it is unlikely that either continual minor
disruptions or less frequent, but more
severe disruptions would occur.
Comment: One individual cited
Schnitzler et al. (2017) in stating that
the varied anatomy of individual sperm
whale ears indicates that ‘‘tolerable’’
sound levels may not be the same for
different animals.
Response: NMFS acknowledges that
actual individual responses to noise
exposure will vary based on a variety of
factors, including individual anatomy
but more likely because of individual
context and experience. However,
sufficient scientific information does
not exist to assess differential impacts to
specific individuals. Therefore, NMFS
uses generic acoustic thresholds in
order to predict potential responses to
noise exposure. However, NMFS has
required a sufficiently robust suite of
mitigation measures to provide
reasonable certainty of general
reduction of takes and of intensity and/
or duration of acoustic exposures for
individual sperm whales.
Comment: The Bald Head Island
Association noted that many marine
mammals have washed up on their
beaches in recent years, including a
beaked whale and juvenile dolphin after
offshore airgun surveys. Sea Shepherd
Legal claimed that NMFS did not
adequately address the potential for
stranding events, noting several studies
that they claim link strandings with
airgun surveys. They also noted that
NMFS did not acknowledge a January
2017 mass stranding of false killer
whales when considering impacts to
species.
Response: Marine mammals are
known to strand for a variety of reasons,
such as infectious agents, biotoxicosis,
starvation, fishery interaction, ship
strike, unusual oceanographic or
weather events, sound exposure, or
combinations of these stressors
sustained concurrently or in series (e.g.,
Geraci et al., 1999). However, the cause
or causes of most strandings are
unknown (e.g., Best, 1982). Stranding
events are known to occasionally
happen as a result of sound exposure,
e.g., Southall et al., 2006, 2013; Jepson
et al., 2013; Wright et al., 2013, with
stranding thought to occur subsequent
to the exposure, as a result of nonauditory physiological effects or
injuries, which theoretically might
occur as a secondary effect of extreme
behavioral reactions (e.g., change in
dive profile as a result of an avoidance
reaction). However, such events are
typically associated with use of military
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tactical sonar, which has very different
characteristics than airgun noise.
NMFS is unaware of any information
linking possible strandings on Bald
Head Island, or in any other location on
the East Coast, with offshore airgun
survey activity, and does not expect the
planned surveys to have any potential to
result in stranding events or the type of
injuries or effects that could lead to
stranding events, given the required
mitigation and operational protocols. In
support of its position, Sea Shepherd
Legal cites two review articles (Gordon
et al., 2003; Compton et al., 2008) that
make general statements regarding the
potential effects of airgun noise and/or
review best practices in mitigation—
NMFS reviewed these papers and
discussed them in our Notice of
Proposed IHAs. Sea Shepherd also cites
a third document (Engel et al., 2004)
questioning whether such surveys may
be responsible for coincident strandings
of humpback whales in Brazil in 2002,
and notes NMFS’s discussion of a 2002
beaked whale stranding event that was
contemporaneous with and reasonably
associated spatially with an airgun
survey in the Gulf of California.
However, unlike for strandings
associated with use of military sonar, no
conclusive causal link was made, and
these observations remain based on
spatial and/or temporal coincidence.
NMFS here acknowledges the 2017
stranding of false killer whales in
Florida referenced by Sea Shepherd
Legal, for which no cause was found.
However, as a precaution NMFS has
modified its reporting requirements to
include protocols relating to
minimization of additional harm to livestranded (or milling) marine mammals.
Addition of these protocols does not
imply any change to our determination
that stranding events are unlikely, nor
does it imply that a stranding event that
does occur is necessarily the result of
the specified activities. However, we
recognize that regardless of the cause of
a stranding event, it is appropriate to
take action in certain circumstances to
avoid additional harm. Please see
‘‘Monitoring and Reporting’’ for more
information.
Marine Mammal Impacts—Habitat
Comment: Many commenters
expressed concern regarding potential
impacts to marine mammal prey and/or
food webs from the planned surveys.
NRDC specifically provided numerous
citations in claiming that the surveys
could impact marine mammal prey
through the following: (1) Cause severe
physical injury and mortality; (2)
damage hearing and sensory abilities of
fish and marine invertebrates; (3)
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impede development of early life
history stages; (4) induce stress that
physically damages marine
invertebrates and compromises fish
health; (5) cause startle and alarm
responses that interrupt vital behaviors;
(6) alter predator avoidance behavior
that may reduce probability of survival;
(7) affect catchability of prey species; (8)
mask important biological sounds
essential to survival; (9) reduce
reproductive success, potentially
jeopardizing long-term sustainability of
fish populations; (10) interrupt feeding
behaviors and induce other speciesspecific effects that may increase risk of
starvation, reduce reproduction, and
alter community structure; and (11)
compromise orientation of fish larvae
with potential ecosystem-level effects.
Additionally, many commenters cited a
recent publication by McCauley et al.
(2017) as evidence that the surveys
could potentially impact zooplankton
and consequently marine mammal food
webs.
In contrast, the International
Association of Geophysical Contractors,
American Petroleum Institute, and
National Ocean Industries Association
(hereafter, ‘‘the Associations’’) stated
that McCauley et al. (2017) ‘‘purports to
demonstrate, but fails to prove, that
seismic survey air sources negatively
impact zooplankton.’’ The Associations
cite small sample size, variability in the
baseline and experimental data, and the
‘‘large number of speculative
conclusions that appear to be
inconsistent with the data collected over
a two-day period’’ in stating that the
research ‘‘creates no reasonable
implication regarding the potential
effects of seismic surveys on marine
mammals.’’
Response: NMFS strongly disagrees
with NRDC’s contention that we ignored
effects to prey species; in fact, we
considered relevant literature (including
that cited by NRDC) in finding that the
most likely impact of survey activity to
prey species such as fish and
invertebrates would be temporary
avoidance of an area, with a rapid return
to recruitment, distribution, and
behavior anticipated. While there is a
lack of specific scientific information to
allow an assessment of the duration,
intensity, or distribution of effects to
prey in specific locations at specific
times and in response to specific
surveys, NMFS’s review of the available
information does not indicate that such
effects could be significant enough to
impact marine mammal prey to the
extent that marine mammal fitness
would be affected. A more detailed
discussion is provided in ‘‘Potential
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Effects of the Specified Activities on
Marine Mammals and Their Habitat.’’
In summary, fish react to sounds
which are especially strong and/or
intermittent low-frequency sounds, and
behavioral responses such as flight or
avoidance are the most likely effects.
However, the reaction of fish to airguns
depends on the physiological state of
the fish, past exposures, motivation
(e.g., feeding, spawning, migration), and
other environmental factors. While we
agree that some studies have
demonstrated that airgun sounds might
affect the distribution and behavior of
some fishes, potentially impacting
foraging opportunities or increasing
energetic costs (e.g., Fewtrell and
McCauley, 2012; Pearson et al., 1992;
Skalski et al., 1992; Santulli et al., 1999;
Paxton et al., 2017), other studies have
shown no or slight reaction to airgun
sounds (e.g., Pena et al., 2013; Wardle
et al., 2001; Jorgenson and Gyselman,
2009; Cott et al., 2012). Most commonly,
though, the impacts of noise on fish are
temporary. Investigators reported
significant, short-term declines in
commercial fishing catch rate of gadid
fishes during and for up to five days
after survey operations, but the catch
rate subsequently returned to normal
(Engas et al., 1996; Engas and
Lokkeborg, 2002); other studies have
reported similar findings (Hassel et al.,
2004).
As discussed by NRDC, however,
even temporary effects to fish
distribution patterns can impact their
ability to carry out important life-history
functions. SPLs of sufficient strength
have been known to cause injury to fish
and fish mortality and, in some studies,
fish auditory systems have been
damaged by airgun noise (McCauley et
al., 2003; Popper et al., 2005; Song et
al., 2008). However, in most fish
species, hair cells in the ear
continuously regenerate and loss of
auditory function likely is restored
when damaged cells are replaced with
new cells. Halvorsen et al. (2012b)
showed that a TTS of 4–6 dB was
recoverable within 24 hours for one
species. Impacts would be most severe
when the individual fish is close to the
source and when the duration of
exposure is long—both of which are
conditions unlikely to occur during
these surveys, which will be transient in
any given location and likely result in
brief, infrequent noise exposure to prey
species in any given area. For these
surveys, the sound source is constantly
moving, and most fish would likely
avoid the sound source prior to
receiving sound of sufficient intensity to
cause physiological or anatomical
damage. In addition, ramp-up may
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allow certain fish species the
opportunity to move further away from
the sound source.
Available data suggest that
cephalopods are capable of sensing the
particle motion of sounds and detect
low frequencies up to 1–1.5 kHz,
depending on the species, and so are
likely to detect airgun noise (Kaifu et al.,
2008; Hu et al., 2009; Mooney et al.,
2010; Samson et al., 2014). Auditory
injuries (lesions occurring on the
statocyst sensory hair cells) have been
reported upon controlled exposure to
low-frequency sounds, suggesting that
cephalopods are particularly sensitive to
low-frequency sound (Andre et al.,
2011; Sole et al., 2013). Behavioral
responses, such as inking and jetting,
have also been reported upon exposure
to low-frequency sound (McCauley et
al., 2000b; Samson et al., 2014). Similar
to fish, however, the transient nature of
the surveys leads to an expectation that
effects will be largely limited to
behavioral reactions and would occur as
a result of brief, infrequent exposures.
With regard to potential impacts on
zooplankton, McCauley et al. (2017)
found that exposure to airgun noise
resulted in significant depletion for
more than half the taxa present and that
there were two to three times more dead
zooplankton after airgun exposure
compared with controls for all taxa,
within 1 km of the airguns. However,
the authors also stated that in order to
have significant impacts on r-selected
species such as plankton, the spatial or
temporal scale of impact must be large
in comparison with the ecosystem
concerned, and it is possible that the
findings reflect avoidance by
zooplankton rather than mortality
(McCauley et al., 2017). In addition, the
results of this study are inconsistent
with a large body of research that
generally finds limited spatial and
temporal impacts to zooplankton as a
result of exposure to airgun noise (e.g.,
Dalen and Knutsen, 1987; Payne, 2004;
Stanley et al., 2011).
A modeling exercise was conducted
as a follow-up to the McCauley et al.
(2017) study (as recommended by
McCauley et al. (2017)), in order to
assess the potential for impacts on
ocean ecosystem dynamics and
zooplankton population dynamics
(Richardson et al., 2017). Richardson et
al. (2017) found that for copepods with
a short life cycle in a high-energy
environment, a full-scale airgun survey
would impact copepod abundance up to
three days following the end of the
survey, suggesting that effects such as
those found by McCauley et al. (2017)
would not be expected to be detectable
downstream of the survey areas, either
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spatially or temporally. However, these
findings are relevant for zooplankton
with rapid reproductive cycles in areas
where there is a high natural
replenishment rate resulting from new
water masses moving in, and the
findings may not apply in lower-energy
environments or for zooplankton with
longer life-cycles. In fact, the study
found that by turning off the current, as
may reflect lower-energy environments,
the time to recovery for the modelled
population extended from several days
to several weeks.
However, while potential impacts to
zooplankton are of obvious concern
with regard to their follow-on effects for
higher-order predators, the survey area
is not an important area for feeding for
taxa that feed directly on zooplankton,
i.e., mysticetes. In the absence of further
validation of the McCauley et al. (2017)
findings, if we assume a worst-case
likelihood of severe impacts to
zooplankton within approximately 1 km
of the acoustic source, the large spatial
scale and expected wide dispersal of
survey vessels does not lead us to
expect any meaningful follow-on effects
to the prey base for odontocete
predators. While the large scale of effect
observed by McCauley et al. (2017) may
be of concern, especially in a more
temperate environment, NMFS
concludes that these findings indicate a
need for more study, particularly where
repeated noise exposure is expected—a
condition unlikely to occur in relation
to these planned surveys. We do not
offer further comment with regard to the
specific criticisms of the Associations,
other than to say that their dismissal of
the study seems to reflect an
unsubstantiated opinion.
Overall, prey species exposed to
sound might move away from the sound
source, experience TTS, experience
masking of biologically relevant sounds,
or show no obvious direct effects.
Mortality from decompression injuries
is possible in close proximity to a
sound, but only limited data on
mortality in response to airgun noise
exposure are available (Hawkins et al.,
2014). The most likely impacts for most
prey species in a given area would be
temporary avoidance of the area. The
surveys are expected to move through
an area relatively quickly, limiting
exposure to multiple impulsive sounds.
In all cases, sound levels would return
to ambient once a survey ends and the
noise source is shut down and, when
exposure to sound ends, behavioral and/
or physiological responses are expected
to end relatively quickly (McCauley et
al., 2000b). The duration of fish
avoidance of a given area after survey
effort stops is unknown, but a rapid
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return to normal recruitment,
distribution, and behavior is
anticipated. While the potential for
disruption of spawning aggregations or
schools of important prey species can be
meaningful on a local scale, the mobile
and temporary nature of the surveys and
the likelihood of temporary avoidance
behavior suggest that impacts would be
minor.
Comment: A group of scientists (C.W.
Clark, S.D. Kraus, D.P. Nowacek, A.J.
Read, M. Rekdahl, A.N. Rice, H.
Rosenbaum, and R.S. Schick) submitted
a collective comment letter. Hereafter,
we refer to this letter as ‘‘Nowacek et
al.’’ Nowacek et al. and NRDC stated
that it is inappropriate to conclude that
these surveys will not impact marine
mammal acoustic habitat, since the
production of airgun noise is known to
increase ambient noise, thereby
negatively impacting habitat. NRDC
further states that NMFS has failed to
adequately account for impacts to
acoustic habitat. In support of their
statements, Nowacek et al. submitted
the results of a sound field modeling
exercise in which they considered
energy produced from seven shots of a
40-element array at 6 m depth (other
important source details were not
provided) across one-third-octave bands
spanning the 71–224 Hz frequency
range. Resulting sound fields were
concatenated at 1-s resolution for two
different water depths (50 and 200 m)
(commenters submitted animations
associated with this exercise; these are
available upon request and are part of
our administrative record for these
actions). They wrote that these
animations highlight the dynamic
nature of the marine environment,
especially the low-frequency sound
field, and the large area over which
sound levels are increased above
ambient levels but below current
regulatory harassment thresholds. The
commenters then correctly note that
consideration of likely takes is limited
to just a portion of the area over which
airgun noise extends into the marine
environment. Nowacek et al. also
recommended that NMFS produce a
quantitative methodology for assessing
the region’s acoustic environment, the
proportional contributions from each of
the natural and anthropogenic noise
inputs, and create mechanisms to
mitigate these lower-level noise
exposures.
Response: The commenters’ claims
that NMFS concluded that there ‘‘would
be no impact to the quality of the
acoustic habitat’’ or suggested that
‘‘there is no basis for acoustic habitat
impacts’’ are erroneous. NMFS made no
such statements, but rather
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acknowledged in our Notice of Proposed
IHAs that it was likely that there would
be impacts to acoustic habitat,
particularly for low-frequency
cetaceans. In fact, we explicitly
considered this likelihood in our
preliminary negligible impact analyses,
finding that ‘‘consequence’’ of the
surveys should be considered as higher
for mysticete whales than for other
species for this reason.
NMFS addressed potential effects to
habitat, including acoustic habitat, and
acknowledges that the surveys will
increase noise levels in the vicinity of
operating source vessels. However,
following consideration of the available
information, NMFS concludes that these
impacts will not significantly affect
ambient noise levels or acoustic
communication space over long time
periods, especially in the context of any
given exposed individual. As described
previously, exploratory surveys such as
these cover a large area but would be
transient rather than focused in a given
location over time and therefore would
not be considered as contributing
meaningfully to chronic effects in any
given location. Given these conclusions,
a separate quantitative analysis of
potential impacts to acoustic habitat, as
is suggested by Nowacek et al., is not
warranted. In contrast, we did develop
and perform such analysis for a different
assessment of much more extensive
geophysical survey activity (see
Appendix K in BOEM, 2017) to be
conducted over a period of ten years,
versus the limited amount of survey
activity to be conducted over a period
of one year here.
We acknowledge and appreciate the
commenters’ scientific expertise, but
there are relevant statutory and
regulatory requirements that inform
NMFS in the scope of analysis relevant
to a finding of negligible impact. Please
see also our response to a previous
comment above, in which NRDC makes
similar charges regarding the impacts of
masking. Finally, regarding terminology
used in the comments (i.e., ‘‘primary
constituent elements’’), the discussion
in this document pertains specifically to
the MMPA and not components related
to critical habitat designated under the
ESA.
Comment: The Sierra Club Marine
Group noted that Cape Hatteras has a
very unique morphology, and that these
features support upwelling that
supports significant biodiversity,
including beaked whales. The
commenters stated that impacts to this
habitat provide a compelling reason to
deny the IHAs.
Response: As described in our Notice
of Proposed IHAs, NMFS concurs that
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Cape Hatteras provides important
habitat for a diverse assemblage of
species, particularly for species such as
sperm whales, beaked whales, pilot
whales, and other species that show
high site fidelity to the area.
Accordingly, NMFS has designed a
time-area restriction encompassing the
area referenced in the comment that
precludes survey effort within the area
for a three-month period (January to
March; Stanistreet et al., 2018); the
restriction is defined specifically to
benefit beaked whales, sperm whales,
and pilot whales, with the specific
timing intended as the most appropriate
for sperm whales. We also require
mitigation to reduce the intensity and
duration of exposure for these species—
particularly for acoustically sensitive
species, such as beaked whales, for
which shutdown is required at an
extended distance of 1.5 km. Separately,
NMFS has required year-round closures
of similar high-relief habitats further
offshore that are predicted to host
relatively high densities of beaked
whales. In addition, the North Atlantic
right whale closure will protect portions
of the area referenced by the
commenters, as it extends out to 90 km
from the coastline (i.e., 80 km plus a 10
km buffer, see ‘‘Mitigation’’) and is in
effect from November through April (or
comparable protection provided through
implementation of a NMFS-approved
mitigation and monitoring plan at
distances between 47–80 km offshore),
whereas the seasonal restriction off of
Cape Hatteras is in effect from January
through March. NMFS believes these
restrictions provide a high degree of
protection to these species and the
habitat they utilize around Cape
Hatteras, while meeting the MMPA’s
least practicable adverse impact
standard. When the contextual factor
addressing required mitigation is
considered, the outcome is a negligible
impact to affected species.
Comment: An individual states that
the surveys have the potential to impair
the Chesapeake Bay, and that such
impairment would have wider
ecological and economic repercussions
beyond the scope of impacting marine
mammals. Similarly, one group
mentioned that impacts from the
surveys could ripple into smaller bays
and inlets elsewhere along the East
Coast, and impact species long after
surveys are complete.
Response: NMFS’s action is
authorizing the taking of marine
mammals pursuant to section
101(a)(5)(D); therefore, impacts of the
survey on aspects of the environment
other than marine mammals and their
habitat are not relevant to NMFS’s
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analysis conducted pursuant to the
MMPA. However, the authorization of
marine mammal take incidental to the
planned surveys would not impact
marine mammals of the Chesapeake Bay
or of other coastal bays and estuaries.
Surveys may not operate closer than 30
km to shore at any time.
North Atlantic Right Whale
Comment: Many commenters
expressed concern regarding the North
Atlantic right whale and potential
impacts of the specified activities, given
their declining population size, an
ongoing Unusual Mortality Event
(UME), declining calf production, and
annual exceedances of the calculated
potential biological removal value (see
‘‘Description of Marine Mammals in the
Area of the Specified Activities—North
Atlantic Right Whale’’ for further
discussion of these issues). Some
commenters noted additional concern
regarding potential survey overlap with
biologically important areas. Others
highlighted concerns regarding
increased risk of ship strike and/or
entanglement with survey vessels, in
addition to the potential for acoustic
and behavioral effects.
Response: NMFS appreciates the
concerns expressed by commenters
regarding right whales. As an agency,
NMFS is working to address the
numerous issues facing right whales,
including continued work to reduce
deaths due to ship strike and
entanglement in fishing gear and
ongoing investigation of the UME, as
well as other measures to investigate
and address the status of the species.
The best available scientific information
shows that the majority of right whale
sightings in the southeast occur in right
whale calving areas from roughly
November through April, with
individual right whales migrating to and
from these areas through mid-Atlantic
shelf waters. Because of these concerns
regarding right whales, NMFS is
requiring closure of these areas (out to
90 km from shore) to survey activity
from November 1 to April 30 (or that
comparable protection is achieved
through implementation of a NMFSapproved mitigation and monitoring
plan at distances between 47–80 km
offshore). This measure is expected to
largely avoid disruption of behavioral
patterns for right whales and to
minimize overall acoustic exposures.
Therefore, NMFS believes that this
restriction provides for migratory
passage to and from calving grounds as
well as avoiding impacts to the whales
while on the grounds. In addition,
NMFS re-evaluated potential right
whale takes using the best available
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scientific information (i.e., Roberts et
al., 2017) and in consideration of the
revised time-area restriction. The result
of this analysis shows that takes of right
whales will be minimal.
Comment: NRDC and, separately,
Nowacek et al. state that airgun surveys
have been linked to significant
reductions in the probability of calf
survival in western Pacific gray whales
(another endangered baleen whale
population), claiming that these
findings indicate that similar surveys off
the southeastern U.S will have
significant negative effects on the
whales that occur anywhere in the
region.
Response: Commenters cite a
preliminary report (Cooke et al., 2015)
that documented a reduction in calf
survival that they suggested may be
related to disruption of foraging from
airgun survey activity and pile driving
in Russia due to presumed avoidance of
foraging areas. However, a more recent
analysis (Cooke et al., 2017) invalidated
these findings, showing that this was a
sampling effect, as those calves that
were assumed dead in the 2015 study
have since been observed alive
elsewhere. The new study found no
significant annual variation in calf
survival. Johnson et al. (2007) had
previously reported that foraging gray
whales exposed to airgun sounds during
surveys in Russia did not experience
any biologically significant or
population-level effects.
Comment: J.J. Roberts and P.N. Halpin
of the Duke University Marine
Geospatial Ecology Lab (hereafter,
‘‘MGEL’’) provided two comments
related to right whales. First, the
commenters stated, in summary, that
the time-area restriction included in our
Notice of Proposed IHAs for the specific
purpose of avoiding impacts to the
North Atlantic right whale would not be
sufficient to achieve its stated purpose.
The commenters noted multiple lines of
scientific evidence that right whales
occur beyond the area defined in the
Notice of Proposed IHAs (i.e., a 20-nmi
coastal strip, superseded by either
critical habitat or seasonal management
areas, and buffered by a distance of 10
km; this equates roughly to a 47-km
coastal strip). The commenters also
reiterated concern regarding an error
associated with the right whale take
estimates for two applicants (TGS and
Western). Finally, the commenters
noted that they were developing
updated density models for the right
whale; these revised models more than
double the survey effort utilized by the
models in the region south of Cape
Hatteras, while additional new data
boost coverage in non-summer seasons.
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As stated by the commenters,
collectively these data allow for a
notable upgrade in right whale density
model performance in the regions and
seasons addressed here. The
commenters noted that, while the
revised models have not been through
formal peer review, they utilize the
same methodology as the Roberts et al.
(2016) publication, which has been peer
reviewed.
Response: We agree with these
comments, and addressed them through
use of the revised North Atlantic right
whale models (Roberts et al., 2017) in
developing new exposure estimates for
all five applicant companies.
Importantly, in agreement with the
statements of the commenters and with
the outputs of the revised models, we
revised the time-area restriction by
increasing the standoff distance from
shore to 90 km (i.e., 80 km plus a 10 km
buffer) (or requiring that comparable
protection is achieved through
implementation of a NMFS-approved
mitigation and monitoring plan at
distances between 47–80 km offshore).
As stated by MGEL and other
commenters, Norris et al. (2014)
reported acoustic detections of right
whales in the southeast beyond the
previous 47 km limit, while Foley et al.
(2011) documented a right whale birth
beyond the previous limit. The right
whale model produced by Roberts et al.
(2016) explicitly included distance from
shore as a predictor in the model; right
whale densities significantly above zero
were predicted beyond the proposed 47
km limit. The revised model retains
distance from shore as a predictor and,
in the region north of Cape Fear,
indicates that right whale density peaks
at about 50 km offshore during the
winter and is moderate to about 80 km
from shore, beyond which limit density
is predicted as dropping off rapidly.
Please see ‘‘Estimated Take—North
Atlantic Right Whale’’ and ‘‘Mitigation’’
for additional discussion.
Comment: Nowacek et al. commented
that NMFS should perform a
quantitative evaluation of right whale
health and reproductive rates, including
mortality and sublethal effects of
entanglement. They noted that tools
such as the Population Consequences of
Disturbance (PCOD) model could be
used to perform such an analysis.
However, Nowacek et al. provided their
own modeling example, including a
health assessment of five North Atlantic
right whales, which they described in
their comment letter. Nowacek et al.’s
analysis showed that a small decrement
in health that could be linked to stress
caused by chronic noise exposure can
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result in negative consequences for
individual right whales.
Response: NMFS appreciates the
attention given to this issue by the
commenters, and finds the analysis
provided in their letter useful. As noted
by many commenters, the primary
threats to the right whale remain ship
strike and entanglement in fishing gear.
However, NMFS considered this
analysis and its conclusions in its
determination to revisit the acoustic
exposure analysis conducted for right
whales and in reconsidering the most
appropriate habitat-based mitigation
requirements related to right whales.
Following these new analyses, NMFS
finds that predicted takes of right
whales have been substantially reduced
and that potential impacts to the right
whale have been reduced to the level of
least practicable adverse impact. While
it is likely not possible to completely
avoid acoustic exposures of North
Atlantic right whales, NMFS finds that
such exposures will be minimized and
that, importantly, the impact of acoustic
exposures will be minimized by
avoiding entirely the habitat expected to
be important for right whales for calving
and migratory behavior (or that
comparable protection is achieved
through implementation of a NMFSapproved mitigation and monitoring
plan at distances between 47–80 km
offshore). In the event that right whales
are encountered outside these areas, the
expanded shutdown requirement will
minimize the severity and/or duration
of acoustic exposures. Finally, while
exposures of right whales at levels
below those expected to result in
disruption of behavioral patterns but
above the level of ambient noise may
occur, NMFS does not consider such
potential exposures as likely to
constitute ‘‘chronic noise exposure,’’ as
a result of the relatively brief duration
of any given survey in any particular
location; therefore, it is unlikely that the
specified activities could result in
impacts such as those assessed through
the analysis of Nowacek et al.
Comment: One commenter described
the relationship between noise and
stress shown by Rolland et al. (2012) for
right whales, stating that the planned
surveys could increase stress in right
whales.
Response: While NMFS concurs that
the findings of Rolland et al. (2012)
indicate a connection between noise
exposure and stress in right whales, the
number of vessels associated with the
surveys is unlikely to contribute to
significant additive vessel traffic and
associated vessel noise as compared
with vessel activity already occurring in
the region. Rolland et al. (2012)
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measured vessel density in an area with
much more concentrated activity (i.e.,
shipping lanes in the Bay of Fundy)
than what would occur in the activity
area. While noise from the surveys,
whether due to use of the airgun arrays
or from the vessels themselves, may
cause stress responses in exposed
animals, NMFS finds it unlikely that
such responses will significantly impact
individual whales as chronic noise
exposure is not expected.
Comment: Several groups commented
on additional data NMFS should have
considered in assessing impacts to
North Atlantic right whales. For
example, the Marine Mammal
Commission (MMC) recommended that
we consult with NMFS’s Northeast
Fisheries Science Center regarding
results of their most recent acoustic
analysis, which they contend may
provide insight on occurrence of right
whales at different distances from shore.
Similarly, Nowacek et al. recommended
that NMFS should consider more recent
data from the Atlantic Marine
Assessment Program for Protected
Species (AMAPPS) surveys or right
whale surveys in the southeast curated
by the North Atlantic Right Whale
Consortium. NRDC stated that NMFS
must use additional data sources in
calculating right whale densities, noting
that recent passive acoustic studies have
detected whales further offshore and
with broader seasonality than
previously expected.
Response: NMFS agrees with these
comments, and has considered these
various sources of newer data, including
by revising acoustic exposure estimates
for right whales by using the latest
density models for right whales (Roberts
et al., 2017). These revised models
incorporate the southeast U.S. right
whale survey data as well as the
AMAPPS data. While the revised model
does not directly incorporate acoustic
data—we note that NRDC offers no
suggestions as to how this might be
accomplished—it was validated through
comparison with passive acoustic
monitoring data (Davis et al., 2017).
While this validation work does suggest
that the revised model may
underestimate right whale presence in
certain locations or seasons—for
example, acoustic data indicate that the
model may underestimate the presence
of whales relatively far from shore
during the winter in the region north of
Cape Hatteras—we developed an
extended right whale closure (out to 90
km from shore) (or we require that
comparable protection is achieved
through implementation of a NMFSapproved mitigation and monitoring
plan at distances between 47–80 km
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offshore) in an effort to reasonably
encompass the likelihood of increased
whale presence at greater distances from
shore than have previously been
expected.
Comment: Sea Shepherd Legal stated
that NMFS ignored the ‘‘Cetacean &
Sound Mapping platform
(‘‘CetSound’’)’’ when discussing
biologically important areas for North
Atlantic right whales.
Response: Though NMFS did not give
specific reference to ‘‘CetSound’’ in our
Notice of Proposed IHAs, we did in fact
incorporate and consider information
available through NOAA’s CetSound
website (cetsound.noaa.gov), including
information relating to BIAs, as
discussed by LaBrecque et al. (2015).
Cumulative Impacts and Related Issues
Comment: Many commenters
expressed concern regarding
‘‘cumulative,’’ ‘‘aggregate’’ and
‘‘synergistic’’ impacts. Commenters
stated that NMFS did not adequately
address cumulative or aggregate impacts
from the five surveys, which are
planned to occur within the same broad
geographic region and which could
overlap temporally. Some commenters
referenced the large amount of survey
effort described in BOEM’s PEIS,
erroneously ascribing the potential
cumulative impacts associated with that
level of effort—associated with nine
years of surveys in support of an active
oil and gas program in the Atlantic—to
the significantly smaller amount of
activity contemplated in our five
separate proposed IHAs. Commenters
urged the agency to review cumulative
impacts using a risk-averse approach,
considering such impacts in the context
of effects to both species and
ecosystems, as well as across time and
geographic extent. As discussed in a
previous comment response, some
commenters cited studies demonstrating
potential long-range propagation of
airgun signals as reason for additional
consideration of cumulative impacts.
Similarly, some commenters claimed a
need to consider takes in the aggregate
and to consider potential takes from
other sources. Nowacek et al. specified
that NMFS should assess aggregate
impacts in addition to cumulative
impacts, highlighting available tools to
do so. One commenter suggested that a
cumulative noise management plan
should be developed. Commenters such
as Nowacek et al. decry our
independent consideration of the effects
of each individual specified activity
under the MMPA as ‘‘completely
without basis in science or logic.’’
Similarly, NRDC claims that failing to
consider the total impact of all five
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surveys in the negligible impact
assessment does not satisfy NMFS’s
legal obligations and is ‘‘contrary to
common sense and principles of sound
science.’’ NRDC also states that NMFS’s
negligible impact determination
underestimates impacts to marine
mammal species and populations
because it fails to consider the effects of
other anticipated activities on the same
marine mammal populations. Finally,
some commenters acknowledged that
the MMPA does not require
consideration of cumulative impacts but
stated that NMFS must do so in this
case given the unprecedented scale of
these surveys in the Atlantic.
Response: Cumulative impacts (also
referred to as cumulative effects) is a
term that appears in the context of
NEPA and the ESA, but it is defined
differently in those different contexts.
Neither the MMPA nor NMFS’s codified
implementing regulations address
consideration of other unrelated
activities and their impacts on
populations. However, the preamble for
NMFS’s implementing regulations (54
FR 40338; September 29, 1989) states in
response to comments that the impacts
from other past and ongoing
anthropogenic activities are to be
incorporated into the negligible impact
analysis via their impacts on the
environmental baseline. Consistent with
that direction, NMFS here has factored
into its negligible impact analyses the
impacts of other past and ongoing
anthropogenic activities via their
impacts on the baseline (e.g., as
reflected in the density/distribution and
status of the species, population size
and growth rate, and other relevant
stressors (such as incidental mortality in
commercial fisheries)). In addition, the
context aspect of our assessment
framework also considers these factors.
See the ‘‘Negligible Impact Analyses
and Determinations’’ section of this
notice.
Our 1989 final rule for the MMPA
implementing regulations also
addressed public comments regarding
cumulative effects from future,
unrelated activities. There we stated
that such effects are not considered in
making findings under section 101(a)(5)
concerning negligible impact. We
indicated that NMFS would consider
cumulative effects that are reasonably
foreseeable when preparing a NEPA
analysis; and also that reasonably
foreseeable cumulative effects would be
considered under section 7 of the ESA
for ESA-listed species.
In this case, we deem each of these
IHAs a future, unrelated activity relative
to the others. Although these IHAs are
all for surveys that will be conducted for
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a similar purpose, they are unrelated in
the sense that they are discrete actions
under section 101(a)(5)(D), issued to
discrete applicants.
Here, we recognize the potential for
cumulative impacts, and that the
aggregate impacts of the five surveys
will be greater than the impacts of any
given survey. The direct aggregate
impacts of multiple surveys were
addressed through the associated NEPA
analyses: In BOEM’s PEIS, which
addressed the impacts of a significantly
greater amount of survey activity that
may be permitted by BOEM, and which
NMFS adopted as the basis for its
Record of Decision; as well as in
NMFS’s tiered Environmental
Assessment, which supported a Finding
of No Significant Impact (FONSI) for the
issuance of the five IHAs here.
In our FONSI, NMFS’s assessment
was focused on whether the predicted
level of take from the five surveys, when
considered in context, would have a
meaningful biological consequence at a
species or population level. NMFS,
therefore, assessed and integrated other
contextual factors (e.g., species’ life
history and biology, distribution,
abundance, and status of the stock;
mitigation and monitoring;
characteristics of the surveys and sound
sources) in determining the overall
impact of issuance of the five IHAs on
the human environment. Key
considerations included the nature of
the surveys and the required mitigation.
In all cases, it is expected that sound
levels will return to previous ambient
levels once the acoustic source moves a
certain distance from the area, or the
surveys cease, and it is unlikely that the
surveys will all occur at the same time
in the same places, as the area within
which the surveys will occur is very
large and some will occur for less than
six months. In other words, we would
not expect the duration of a sound
source to be greater than moderate and
intermittent in any given area. Surveys
have been excluded from portions of the
total area deemed to result in the
greatest benefit to marine mammals.
These restrictions will not only reduce
the overall numbers of take but, more
importantly, will eliminate or minimize
impacts to marine mammals in the areas
most important to them for feeding,
breeding, and other important functions.
Therefore, these measures are expected
to meaningfully reduce the severity of
the takes that do occur by limiting
impacts that could reduce reproductive
success or survivorship.
In summary, NMFS finds that when
the required mitigation and monitoring
is considered in combination with the
large spatial extent over which the
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activities are spread across for
comparatively short durations (less than
one year), the potential impacts are both
temporary and relatively minor.
Therefore, NMFS does not expect
aggregate impacts from the five surveys
to marine mammals to affect rates of
recruitment or survival, either alone or
in combination with other past, present,
or ongoing activities. The cumulative
impacts of these surveys (i.e., the
incremental impact of the action when
added to other past, present, and
reasonably foreseeable future actions)
were addressed as required through the
NEPA documents cited above and, as
noted, supported a FONSI for the five
IHAs. These documents, as well as the
relevant Stock Assessment Reports, are
part of NMFS’s Administrative Record
for this action, and provided the
decision-maker with information
regarding other activities in the action
area that affect marine mammals, an
analysis of cumulative impacts, and
other information relevant to the
determinations made under the MMPA.
Separately, cumulative effects were
analyzed as required through NMFS’s
required intra-agency consultation
under section 7 of the ESA, which
concluded that NMFS’s action of issuing
the five IHAs was not likely to
jeopardize the continued existence of
listed marine mammals and was not
likely to adversely affect any designated
critical habitat.
We note that section 101(a)(5)(D) of
the MMPA requires NMFS to make a
determination that the take incidental to
a ‘‘specified activity’’ will have a
negligible impact on the affected species
or stocks of marine mammals, and will
not result in an unmitigable adverse
impact on the availability of marine
mammals for taking for subsistence
uses. We believe the ‘‘specified activity’’
for which incidental take coverage is
being sought under section 101(a)(5)(D)
is appropriately defined and described
by the IHA applicant, just as with
applications submitted for section
101(a)(5)(A) incidental take regulations.
Here there are five specified activities,
with a separate applicant for each.
NMFS must make the necessary
findings for each specified activity.
Comment: Several commenters
discussed a recent report from the
National Academy of Sciences
concerning cumulative impacts to
marine mammals (‘‘Approaches to
Understanding the Cumulative Effects of
Stressors on Marine Mammals’’; NAS,
2017), suggesting that NMFS should
have reviewed this report in addressing
cumulative impacts.
Response: NMFS acknowledges the
importance of this new report, which
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was not available at the time of writing
for our Notice of Proposed IHAs. We
reviewed this report and considered its
findings in relation to our
considerations pursuant to NEPA as
well as with regard to its general
findings for marine mammals.
Behavioral disturbance or stress may
reduce fitness for individual animals
and/or may exacerbate existing declines
in reproductive health and survivorship.
For example, stressors such as noise and
pollutants can induce responses
involving the neuroendocrine system,
which controls reactions to stress and
regulates many body processes (NAS,
2017). As an example, Romano et al.
(2004) found that upon exposure to
noise from a seismic watergun,
bottlenose dolphins had elevated levels
of a stress-related hormone and,
correspondingly, a decrease in immune
cells. Population-level impacts related
to energetic effects or other impacts of
noise are difficult to determine, but the
addition of other stressors can add
considerable complexity due to the
potential for interaction between the
stressors or their effects (NAS, 2017).
When a population is at risk NAS (2017)
recommends identifying those stressors
that may feasibly be mitigated. In this
case, we have done so by prescribing a
comprehensive suite of mitigation
measures that both specifically tailors
real-time detection and mitigation
requirements to the species most
sensitive to noise from airguns or to
additional stressors in general (due to
overall vulnerability of the stock), and
includes habitat-based mitigation that
restricts survey effort in the areas and
times expected to be most important for
the species at greatest risk of more
severe impacts from the specified
activities (or requires comparable
protection via other methods).
Acoustic Thresholds
Comment: NRDC and several other
commenters criticized NMFS’s use of
the 160-dB rms Level B harassment
threshold, stating that the threshold is
based on outdated information and that
current research shows that behavioral
impacts can occur at levels below the
threshold. Criticism of our use of this
threshold also focused on its nature as
a step function, i.e., it assumes animals
don’t respond to received noise levels
below the threshold but always do
respond at higher received levels.
Several organizations also suggest that
reliance on this threshold results in
consistent underestimation of impacts.
Commenters urged the agency to
provide additional technical acoustic
guidance regarding thresholds for
behavioral harassment and stated that
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no determinations regarding the
proposed IHAs can be made until such
new guidance has been developed.
NRDC specifically stated that NMFS
should employ specific thresholds for
which species-specific data are
available, and then create generalized
thresholds for other species, and that
the thresholds should be expressed as
linear risk functions where appropriate
to account for intraspecific and
contextual variability. NRDC and others
suggested that NMFS must revise the
threshold as suggested in Nowacek et al.
(2015), which recommended a dose
function centered on 140 dB rms. TGS
suggested that NMFS should re-evaluate
take estimates using the approach
described in Wood et al. (2012).
Response: NMFS acknowledges that
the 160-dB rms step-function approach
is simplistic, and that an approach
reflecting a more complex probabilistic
function may more effectively represent
the known variation in responses at
different levels due to differences in the
receivers, the context of the exposure,
and other factors. Certain commenters
suggested that our use of the 160-dB
threshold implies that we do not
recognize the science indicating that
animals may react in ways constituting
behavioral harassment when exposed to
lower received levels. However, we do
recognize the potential for Level B
harassment at exposures to received
levels below 160 dB rms, in addition to
the potential that animals exposed to
received levels above 160 dB rms will
not respond in ways constituting
behavioral harassment. These comments
appear to evidence a misconception
regarding the concept of the 160-dB
threshold. While it is correct that in
practice it works as a step-function, i.e.,
animals exposed to received levels
above the threshold are considered to be
‘‘taken’’ and those exposed to levels
below the threshold are not, it is in fact
intended as a sort of mid-point of likely
behavioral responses (which are
extremely complex depending on many
factors including species, noise source,
individual experience, and behavioral
context). What this means is that,
conceptually, the function recognizes
that some animals exposed to levels
below the threshold will in fact react in
ways that are appropriately considered
take, while others that are exposed to
levels above the threshold will not. Use
of the 160-dB threshold allows for a
simplistic quantitative estimate of take,
while we can qualitatively address the
variation in responses across different
received levels in our discussion and
analysis.
NRDC consistently cites reports of
changes in vocalization, typically for
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baleen whales, as evidence in support of
a lower threshold than the 160-dB
threshold currently in use. A mere
reaction to noise exposure does not,
however, mean that a take by Level B
harassment, as defined by the MMPA,
has occurred. For a take to occur
requires that an act have ‘‘the potential
to disturb by causing disruption of
behavioral patterns,’’ not simply result
in a detectable change in motion or
vocalization. Even a moderate cessation
or modification of vocalization might
not appropriately be considered as being
of sufficient severity to result in take
(Ellison et al., 2012). NRDC claims these
reactions result in biological
consequences indicating that the
reaction was indeed a take but does not
provide a well-supported link between
the reported reactions at lower received
levels and the claimed consequences. In
addition, NRDC fails to discuss
documented instances of marine
mammal exposure to received levels
greater than 160 dB that did not elicit
any response. Just a few examples are
presented here:
• Malme et al. (1985) conducted a
study consisting of playback using a
stationary or moving single airgun and
humpback whales. No clear overall
signs of avoidance of the area were
recorded for feeding/resting humpback
whales exposed to received levels up to
172 dB. Although startle responses were
observed when the airgun was first
turned on, likely due to the novelty of
the sound, increasing received levels
did not result in increasing probability
of avoidance. In three instances, whales
actually approached the airgun.
• Malme et al. (1988) conducted a
controlled exposure experiment
involving a moving single airgun and
gray whales. From this study, the
authors predicted a 0.5 probability that
whales would stop feeding and move
away from the area when received levels
reached 173 dB and a 0.1 probability of
feeding interruption at a received level
of 163 dB. However, whale responses
were highly variable, with some whales
remaining feeding with received levels
as high as 176 dB.
• McCauley et al. (1998, 2000a,
2000b) report observations associated
with an actual seismic survey (array
volume 2,678 in 3) and controlled
approaches of humpback whales with a
single airgun. When exposed to the
actual seismic survey, avoidance
maneuvers for some whales began at a
range of 5–8 km from the vessel;
however, in three trials whales at a
range beyond 5 km showed no
discernible effects on movement
patterns. In addition, some male
humpback whales were attracted to the
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single airgun (maximum received level
of 179 dB). Overall, McCauley et al.
(2000a) found no gross disruption of
humpback whale movements in the
region of the source vessel, based on
encounter rates.
• Malme et al. (1983, 1984)
conducted playback experiments with
gray whales involving a single airgun
and a full array (2,000–4,000 in 3). For
playback of the array, it was estimated
that probability of avoidance during
migration (including moving inshore
and offshore to avoid the area or to pass
the noise source at a greater distance
then would normally occur) was 0.1 at
164 dB; 0.5 at 170 dB; and 0.9 at levels
greater than 180 dB.
These examples are related only to
baleen whales, for which NRDC
provides examples of vocalization
changes in response to noise exposure.
Although associated received levels are
not available, a substantial body of
evidence indicates that delphinids are
significantly more tolerant of exposure
to airgun noise. Based on review of
monitoring reports from many years of
airgun surveys, many delphinids
approach acoustic source vessels with
no apparent discomfort or obvious
behavioral change (Barkaszi et al., 2012;
Stone, 2015a). Behavioral observations
of gray whales during an airgun survey
monitored whale movements and
respirations pre-, during-, and postseismic survey (Gailey et al., 2016).
Behavioral state and water depth were
the best ‘natural’ predictors of whale
movements and respiration and, after
considering natural variation, none of
the response variables were significantly
associated with survey or vessel sounds.
Overall, we reiterate the lack of
scientific consensus regarding what
criteria might be more appropriate.
Defining sound levels that disrupt
behavioral patterns is difficult because
responses depend on the context in
which the animal receives the sound,
including an animal’s behavioral mode
when it hears sounds (e.g., feeding,
resting, or migrating), prior experience,
and biological factors (e.g., age and sex).
Other contextual factors, such as signal
characteristics, distance from the
source, and signal to noise ratio, may
also help determine response to a given
received level of sound. Therefore,
levels at which responses occur are not
necessarily consistent and can be
difficult to predict (Southall et al., 2007;
Ellison et al., 2012; Bain and Williams,
2006).
There is currently no agreement on
these complex issues, and NMFS
followed the practice at the time of
submission and review of these
applications in assessing the likelihood
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of disruption of behavioral patterns by
using the 160-dB threshold. This
threshold has remained in use in part
because of the practical need to use a
relatively simple threshold based on
available information that is both
predictable and measurable for most
activities. We note that the seminal
review presented by Southall et al.
(2007) did not suggest any specific new
criteria due to lack of convergence in
the data. NMFS is currently evaluating
available information towards
development of guidance for assessing
the effects of anthropogenic sound on
marine mammal behavior. However,
undertaking a process to derive
defensible exposure-response
relationships is complex (e.g., NMFS
previously attempted such an approach,
but is currently re-evaluating the
approach based on input collected
during peer review of NMFS (2016)). A
recent systematic review by Gomez et
al. (2016) was unable to derive criteria
expressing these types of exposureresponse relationships based on
currently available data.
NRDC consistently cites Nowacek et
al. (2015) in public comments,
suggesting that this paper is indicative
of a scientific consensus that NMFS is
missing or ignoring. We note first that
while NRDC refers to this paper as a
‘‘study’’ (implying that it presents new
scientific data or the results of new
analyses of existing scientific data), the
paper in fact makes policy
recommendations rather than presenting
any new science. The more substantive
reviews presented by Southall et al.
(2007) and Gomez et al. (2016) were
unable to present any firm
recommendations, as noted above.
Other than suggesting a 50 percent
midpoint for a probabilistic function,
Nowacek et al. (2015) offer minimal
detail on how their recommended
probabilistic function should be
derived/implemented or exactly how
this midpoint value (i.e., 140 dB rms)
was derived (i.e., what studies support
this point). In contrast with elements of
a behavioral harassment function that
NRDC indicates as important in their
comments, Nowacek et al. (2015) does
not make distinctions between any
species or species groups and provide
no quantitative recommendations for
acknowledging that behavioral
responses can vary by species group
and/or behavioral context. In summary,
little substantive support is provided by
Nowacek et al. (2015) for the proposal
favored by NRDC and it is treated in that
paper as a vague recommendation with
minimal support offered only in a onepage supplementary document rather
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than well-supported scientific
consensus, as the commenter suggests.
NMFS disagrees that establishing
species-specific thresholds is practical
(i.e., this approach would make
assessments unnecessarily onerous by
creating numerous thresholds to
evaluate). Additionally, there is
scientific evidence that grouping
thresholds by broad source category
(Gomez et al., 2016) or taxonomic group
(NMFS, 2018) is supportable. NMFS
currently uses data/thresholds from
surrogate species/groups to represent
those species/groups where data are not
available.
Overall, while we agree that there
may be methods of assessing likely
behavioral response to acoustic stimuli
that better capture the variation and
context-dependency of those responses
than the simple step-function used here,
there is no agreement on what that
method should be or how more
complicated methods may be
implemented by applicants. NMFS is
committed to continuing its work in
developing updated guidance with
regard to acoustic thresholds, but
pending additional consideration and
process is reliant upon an established
threshold that is reasonably reflective of
available science.
In support of exploring new methods
for quantitatively predicting behavioral
harassment, we note NMFS’s recently
published proposed incidental take
regulations for geophysical surveys in
the Gulf of Mexico (83 FR 29212; June
22, 2018), which propose using the
modeling study first published in
BOEM’s associated EIS (Appendix D in
BOEM, 2017) to estimate take. This
study evaluated potential disruption of
behavioral patterns that could result
from a program of airgun surveys, using
both the 160-dB step function and a
probabilistic risk function similar to that
suggested by Nowacek et al. (2015), but
with a midpoint set at 160 dB for the
majority of species, rather than 140 dB.
This function, described in Wood et al.
(2012), includes for most species a 10
percent probability of behavioral
harassment at 140 dB, with subsequent
steps of 50 percent at 160 dB and 90
percent at 180 dB. Of note, use of this
generic function resulted in lower
numbers of estimated takes than did use
of the 160-dB step function. Therefore,
while use of the probabilistic risk
function may allow for more specific
quantitative consideration of contextual
issues and variation in individual
responses, our use of the 160-dB step
function is conservative in that the
number of resulting takes is higher.
NMFS will continue to explore
quantitative refinement of the
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behavioral harassment threshold where
there is available information to support
methodologies that better reflect the
variation in individual responses.
However, the current threshold allows
for an appropriate, and often
conservative, enumeration of predicted
takes by Level B harassment, which
support robust negligible impact and
small numbers analyses.
Comment: Nowacek et al. stated that
use of the 160-dB threshold would be
specifically problematic for beaked
whales, as these species demonstrate
behavioral response at levels below 160
dB rms and occupy certain areas of the
specific geographic region in high
densities.
Response: Please see our previous
comment response regarding use of the
160-dB threshold for behavioral
harassment. With regard to the expected
significance of takes by harassment
specifically for beaked whales, we
acknowledge that beaked whales are
documented as being a particularly
behaviorally sensitive species in
response to noise exposure. This
information is considered in our
negligible impact analyses (‘‘Negligible
Impact Analyses and Determinations’’)
and informed our evaluation of the
mitigation necessary to satisfy the least
practicable adverse impact standard
(‘‘Mitigation’’). We require
implementation of three year-round
closures of submarine canyon areas
expected to provide important habitat
for beaked whales, a seasonal closure of
the area off of Cape Hatteras cited by the
commenters, and have required
expanded shutdown requirements for
beaked whales. Additionally, regarding
the specific levels at which they are
behaviorally harassed by exposure to
noise from airguns, we note that there
are no data on beaked whale responses
to airgun noise, and their hearing
sensitivity in the frequency range of
signals produced by airguns is notably
lower than their sensitivity in the
frequency range of the sonar sources for
which data is available indicating that
they have responded at lower levels (in
other words, noise from an airgun must
be louder than a sonar pulse for them
to hear it as the same level).
Comment: NRDC and others stated
that if NMFS does not revise existing
behavioral harassment thresholds, it
should use the acoustic threshold for
continuous noise (i.e., 120 dB rms)
rather than the threshold for
intermittent sound sources (i.e., 160 dB
rms). NRDC contends that, as a result of
reverberation and multipath arrivals, the
impulsive signal produced by airguns is
more similar to a continuous noise at
greater distances from the source and,
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therefore, use of the 120-dB
‘‘continuous’’ noise threshold is more
appropriate than the 160-dB threshold
for intermittent sound sources.
Response: NMFS acknowledges that
as airgun shots travel through the
environment, pulse duration increases
because of reverberation and multipath
propagation. However, we disagree that
the 120-dB rms threshold for continuous
noise—which was based on behavioral
responses of baleen whales to drilling
(Malme et al., 1984; Richardson et al.,
1990)—is more appropriate than the
intermittent noise threshold of 160-dB
rms for evaluating potential behavioral
harassment resulting from airgun noise.
The 160-dB threshold was derived from
data for mother-calf pairs of migrating
gray whales (Malme et al., 1983, 1984)
and bowhead whales (Richardson et al.,
1985, 1986) behaviorally responding
when exposed specifically to noise from
airguns. The Richardson et al. (1985,
1986) studies included controlled
approaches with a full-scale airgun
array firing at 7.5 km from the animals.
Thus, behavioral responses observed in
these studies account for changes in the
pulse duration associated with
propagation.
In addition, there is a prevalent
misconception in comments from NRDC
and others regarding Level B
harassment, as defined by the MMPA.
NRDC cites multiple observations of
behavioral reactions or of changes in
vocal behavior in making statements
supporting their overall
recommendation that behavioral
harassment thresholds be lower.
However, these observations do not
necessarily constitute evidence of
disruption of behavioral patterns (Level
B harassment) rather than simple
reactions to often distant noise, which
may provoke a reaction when
discernable above ambient noise levels.
For example, changes in mysticete
vocalization associated with exposure to
airgun surveys within migratory and
non-migratory contexts have been
observed (e.g., Castellote et al., 2012;
Blackwell et al., 2013; Cerchio et al.,
2014). The potential for these changes to
occur over large spatial scales is not
surprising for species with large
communication spaces, like mysticetes
(e.g., Clark et al., 2009), although not
every change in a vocalization would
necessarily rise to the level of a take.
Comment: NRDC claims that NMFS
misapplies the MMPA’s statutory
definition of harassment by adopting a
probability standard other than
‘‘potential’’ in setting thresholds for
auditory injury, stating that a take
estimate based on ‘‘potential’’ should
either count take from the lowest
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exposure level at which hearing loss can
occur or establish a probability function
that accounts for variability in the
acoustic sensitivity of individual marine
mammals. Instead, NRDC states that
NMFS derived auditory injury
thresholds from average exposure levels
at which tested marine mammals
experience hearing loss, which
discounts instances of hearing loss at
lower levels of exposure. The comment
goes on to state that for purposes of take
estimation, thresholds based on mean or
median values will lead to roughly half
of an exposed cohort experiencing the
impacts that the threshold is designed to
avoid, at levels that are considered
‘‘safe,’’ therefore resulting in substantial
underestimates of auditory injury.
NRDC makes similar statements with
regard to the 160-dB threshold for Level
B harassment.
Response: The technical guidance’s
(NMFS, 2018) onset thresholds for
temporary threshold shift (TTS) for nonimpulsive sounds encompass more than
90 percent of available TTS data (i.e., for
mid-frequency cetaceans, only two data
points are below the onset threshold,
with maximum point only 2 dB below),
and in some situations 100 percent of
TTS data (e.g., high-frequency
cetaceans; although this group is datalimited). Thus, the technical guidance
thresholds provide realistic predictions,
based on currently available data, of
noise-induced hearing loss in marine
mammals. For impulsive sounds, data
are limited to two studies, and NMFS
directly adopted the TTS onset levels
from these two studies for the
applicable hearing groups.
Our Federal Register notice
announcing the availability of the
original technical guidance (81 FR
51694; August 4, 2016; NMFS, 2016),
indicated that onset of auditory injury
(PTS) equates to Level A harassment
under the MMPA. We explained in that
notice that because the acoustic
thresholds for PTS conservatively
predict the onset of PTS, they are
inclusive of the ‘‘potential’’ language
contained in the definition of Level A
harassment. See 81 FR 51697, 51721.
Regarding Level B harassment, based
on the language and structure of the
definition of Level B harassment, we
interpret the concept of ‘‘potential to
disturb’’ as embedded in the assessment
of the behavioral response that results
from an act of pursuit, torment, or
annoyance (collectively referred to
hereafter as an ‘‘annoyance’’). The
definition refers to a ‘‘potential to
disturb’’ by causing disruption of
behavioral patterns. Thus, an analysis
that indicates a disruption in behavioral
patterns establishes the ‘‘potential to
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disturb.’’ A separate analysis of
‘‘potential to disturb’’ is not needed. In
the context of an authorization such as
this, our analysis is forward-looking.
The inquiry is whether we would
reasonably expect a disruption of
behavioral patterns; if so, we would
conclude a potential to disturb and
therefore expect Level B harassment. We
addressed NRDC’s concerns regarding
the scientific support for the Level B
harassment threshold in a previous
comment response.
Comment: The Center for Regulatory
Effectiveness (CRE) does not agree with
NMFS’s use of the technical acoustic
guidance (NMFS, 2016, 2018) for
purposes of evaluating potential
auditory injury. CRE claims that (1)
NMFS’s use of the guidance conflicts
with Executive Order 13795
(‘‘Implementing an America-First
Offshore Energy Strategy’’); (2) the
guidance violates the Office of
Management and Budget’s (OMB) Peer
Review Bulletin and Guidance
Document Bulletin and implementing
Memoranda; (3) violates Information
Quality Act (IQA) guidelines; and (4)
violates Executive Orders 12866
(‘‘Regulatory Planning and Review’’)
and 13771 (‘‘Reducing Regulation and
Controlling Regulatory Costs’’).
Regarding the IQA, CRE states that
NMFS does not have an OMB-approved
Information Collection Request (ICR)
associated with the guidance, and is
therefore violating the IQA. The CRE
also claims that NMFS’s use of the
guidance violates the MMPA
requirement that all mitigation
requirements be practicable, as the
guidance supposedly requires
monitoring and reporting requirements
and other mitigation requirements that
are impossible to comply with.
Response: NMFS disagrees that use of
the technical guidance results in any of
the claims listed by CRE. First, the use
of the technical guidance does not
conflict with Executive Order 13795.
Section 10 of the Executive Order called
for a review of the technical guidance
(NMFS, 2016) as follows: ‘‘The
Secretary of Commerce shall review for
consistency with the policy set forth in
Section 2 of this order and, after
consultation with the appropriate
Federal agencies, take all steps
permitted by law to rescind or revise
that guidance, if appropriate.’’ To assist
the Secretary in the review of the
technical guidance, NMFS solicited
public comment via a 45-day public
comment period (82 FR 24950; May 31,
2017) and hosted an interagency
consultation meeting with
representatives from ten federal
agencies (September 25, 2017). NMFS
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provided a summary of comments and
recommendations received during this
review to the Secretary, and per the
Secretary’s approval, issued a revised
version of the technical guidance in
June 2018 (83 FR 28824; NMFS, 2018).
Second, NMFS did comply with the
OMB Peer Review Bulletin and IQA
Guidelines in development of the
technical guidance. The technical
guidance was classified as a Highly
Influential Scientific Assessment and, as
such, underwent three independent
peer reviews, at three different stages in
its development, including a follow-up
to one of the peer reviews, prior to its
dissemination by NMFS. In addition,
there were three separate public
comment periods. Responses to public
comments were provided in a previous
Federal Register notice (81 FR 51694;
August 4, 2016). Detailed information
on the peer reviews and public
comment periods conducted during
development of the guidance are
included as an appendix to the
guidance, and are detailed online at:
www.cio.noaa.gov/services_programs/
prplans/ID43.html.
Furthermore, the technical guidance
is not significant for purposes of
Executive Orders 12866 or 13771 or
OMB’s Bulletin entitled, ‘‘Agency Good
Guidance Practices’’ for significant
guidance documents. 72 FR 3432
(January 25, 2007). Nevertheless, the
technical guidance follows the practices
and includes disclaimer language
suggested by the OMB Bulletin to
communicate effectively to the public
about the legal effect of the guidance.
Finally, with regard to the claim that
NMFS’s use of the technical guidance
violates the MMPA requirement that all
mitigation requirements be practicable,
as the guidance supposedly requires
monitoring and reporting requirements
and other mitigation requirements that
are impossible to comply with, we
reiterate that mitigation and monitoring
requirements associated with an MMPA
authorization or ESA consultation or
permit are independent management
decisions made in accordance with
statutory and regulatory standards in the
context of a proposed activity and
comprehensive effects analysis and are
beyond the scope of the technical
guidance. The technical guidance does
not mandate mitigation or monitoring.
Finally, there is no collection of
information requirement associated
with the technical guidance, so no ICR
is required.
Comment: Several groups raised
concerns regarding use of the technical
acoustic guidance (NMFS, 2016, 2018),
claiming that the guidance is not based
on the best available science and
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underestimates potential auditory
injury. NRDC specifically cited many
supposed issues with the guidance,
including adoption of ‘‘erroneous’’
models, broad extrapolation from a
small number of individuals, and
disregarding ‘‘non-linear accumulation
of uncertainty.’’ NRDC suggests that
NMFS retain the historical 180-dB rms
Level A harassment threshold as a
‘‘conservative upper bound’’ or conduct
a ‘‘sensitivity analysis’’ to ‘‘understand
the potential magnitude’’ of the
supposed errors. Oceana stated that
NMFS should not make a decision about
the proposed IHAs while the technical
guidance is under review.
Response: The original 2016 technical
guidance and revised 2018 guidance is
a compilation, interpretation, and
synthesis of the scientific literature that
provides the best available information
regarding the effects of anthropogenic
sound on marine mammals’ hearing.
The technical guidance was classified as
a Highly Influential Scientific
Assessment and, as such, underwent
three independent peer reviews, at three
different stages in its development,
including a follow-up to one of the peer
reviews, prior to its dissemination by
NMFS. In addition, there were three
separate public comment periods,
during which time we received and
responded to similar comments on the
guidance (81 FR 51694), and more
recent public and interagency review
under Executive Order 13795. While
new information may help to improve
the guidance in the future, and NMFS
will review the available literature to
determine when revisions are
appropriate, the final guidance reflects
the best available science and all
information received through peer
review and public comment. Given the
systematic development of the
guidance, which was also reviewed
multiple times by both independent
peer reviewers and the public, NRDC’s
use of the phrase ‘‘arbitrary and
capricious’’ is unreasonable.
The guidance updates the historical
180-dB rms injury threshold, which was
based on professional judgement (i.e.,
no data were available on the effects of
noise on marine mammal hearing at the
time this original threshold was
derived). NMFS does not believe the use
of the technical guidance provides
erroneous results. The 180-dB rms
threshold is plainly outdated, as the best
available science indicates that rms SPL
is not even an appropriate metric by
which to gauge potential auditory injury
(whereas the scientific debate regarding
behavioral harassment thresholds is not
about the proper metric but rather the
proper level or levels and how these
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may vary in different contexts). NRDC’s
advice to return to use of the 180-dB
threshold is inconsistent with its
criticism of the 160-dB rms criterion for
Level B harassment. However, as we
said in responding to comments
criticizing the Level B harassment
criterion, development of an updated
threshold(s) is complicated by the
myriad contextual and other factors that
must be considered and evaluated in
reaching appropriate updated criteria.
See our response to comment on the
Level B harassment threshold.
Sound Field Modeling
Comment: The MMC noted
differences in the estimated Level B
harassment radii provided in ION and
Spectrum’s applications, noting that
since the largest discrepancies were
observed at shallow water sites, it is
likely that geoacoustic properties were
responsible. Although both ION and
Spectrum used sediment data from
cores collected during the Ocean
Drilling Program, the data was based on
samples from different sites and
potentially different assumptions as to
sediment attenuation. The MMC
provided related recommendations: (1)
NMFS should determine whether ION’s
or Spectrum’s estimated zones are the
most appropriate and require that both
companies use the same set of zones; (2)
NMFS should require each of the five
companies to conduct sound source
verification (SSV) in waters less than
100 m and use that data to inform and
adjust the extent of Level B harassment
zones as necessary; and (3) NMFS
should determine the appropriate
baseline geoacoustic model for the
region in concert with BOEM, ION, and
Spectrum, and then require this in
future IHAs for similar activities in the
region.
Response: NMFS appreciates the
MMC’s attention to this matter, but
disagrees that it is necessarily
appropriate to require use of the same
data or approaches to modeling sound
fields when there is not clearly a ‘‘most
appropriate’’ approach. Sound field
modeling for both ION and Spectrum
was conducted by experts in the field.
We appropriately approved both
applicants’ applications as adequate and
complete, determining that both used
appropriate data inputs and acceptable
modeling approaches. Subsequently,
both applications were made available
for public review in order to better
inform NMFS’s preparation of proposed
IHAs; no such concerns were raised.
Importantly, we recognize that there is
no model or approach that is always the
most appropriate and that there may be
multiple approaches that may be
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considered acceptable. Having
determined that both applicants used
appropriate data and acceptable
modeling approaches, it would be
inappropriate to require one to change
their approach to conform to the other
because of differences in the results.
Given our confidence in the data inputs
and modeling approaches used, we find
that a requirement to conduct SSV
studies is not warranted, despite
discrepancies in modeling results. As is
appropriate, NMFS would consider the
appropriateness of data inputs and
modeling approaches for any future
applications but, in keeping with our
response here, will not necessarily
enforce use of one dataset or modeling
approach when others may be
considered as equally representative of
the best available scientific data and
techniques.
Comment: One individual suggested
that, because the representative airgun
array used in BOEM’s sound field
modeling was characterized as having a
source level lower than that of arrays
planned for use by the applicants, use
of BOEM’s sound field modeling could
lead to an underestimate of takes.
Response: Numerous factors combine
in the sound field modeling provided by
BOEM to result ultimately in estimates
of sound fields at different locations.
BOEM’s modeling was performed to be
reasonably representative of the types of
sources that would be used in future
surveys, recognizing that actual sources
may vary somewhat from what was
considered in the sound field modeling.
We disagree that these minor differences
would have meaningful impacts on the
ultimate result of the exposure
estimation process, and find that the
modeling provided by BOEM was
reasonably representative of what would
occur during actual surveys and,
therefore, acceptable to use for
informing the take estimates for these
surveys.
Comment: One individual stated that
NMFS does not fully consider the
implications of different weather
phenomena in acoustic propagation,
and that in failing to account for
variations in ocean and weather
conditions, the average estimates of
propagation and take are biased
downward. The same individual also
claimed that NMFS did not adequately
consider ocean floor sediment
composition in modeling expected
sound fields, and states again that this
would likely result in higher numbers of
take.
Response: While NMFS acknowledges
that discrete weather phenomena could
result in propagation being more or less
efficient than anticipated under a
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seasonal average scenario (i.e., one
element of propagation modeling is the
use of sound velocity profiles that are
season-specific within the specific
geographic region), the commenter
provides no basis for concluding that
such phenomena would lead overall to
the estimated takes being biased
downward. Further, the sound field
modeling approaches taken by the
applicants (and in BOEM’s PEIS) follow
state-of-science approaches and are
reasonable when considering the need
to model propagation year-round and
over a wide geographic area. The
commenter provides no specific
recommendation for how the suggestion
should be accomplished. With regard to
sediment composition, the applicants’
sound field modeling considered
sediment characteristics at 15
representative modeling sites
throughout the region, and the
commenter does not provide any
evidence to back the claim that
variability in actual sediment
composition would result in bias to take
estimates in a particular direction or
provide any specific recommendation to
remedy the perceived flaw.
Comment: Ocean Conservation
Research (OCR) noted that NMFS did
not consider a secondary transmission
path in the mixed layer above the
marine thermocline that behaves as a
surface duct, stating that, while the
propagation in this transmission path is
dependent on the wavelength of the
source, the angle of incidence, the depth
of the mixed layer, and the surface
conditions, the attenuation
characteristics are more consistent with
the cylindrical spreading model. OCR
goes on to claim that, assuming
cylindrical propagation of surface
ducted noise, typical airgun noise
would require 13 km to attenuate to a
received level of 180 dB rms.
Response: Although OCR is correct to
point out that the mechanism of sound
propagation is complex in the ocean
environment, with the potential
formation of a surface duct as a result
of the mixed layer above the permanent
thermocline, the conclusion derived by
OCR that typical airgun noise would
require 13 km to attenuate to a received
level of 180 dB rms is unsupported.
First, oceanographic conditions in the
mid-Atlantic region do not support a
persistent surface duct, which usually
occurs after a storm or consistently cool
and windy weather. A reduction of
surface wind velocity and the warming
of the surface water will quickly break
down a surface duct and cause the
downward refraction of a shallow
source (e.g., source from an airgun
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array) due to a negative sound velocity
profile above the thermocline.
Second, as stated above, the formation
of a surface duct requires strong wind
gusts and a high sea state, which are not
ideal conditions for conducting a
seismic survey given the need to tow a
large array of airguns and long
streamers. Thus, even if a surface duct
is formed, it is very unlikely that a
seismic survey would continue under
such conditions.
Third—as OCR correctly pointed
out—sound propagation in a surface
duct is dependent on the wavelength of
the source, the angle of incidence, the
depth of the mixed layer, and the
surface conditions. Among these
parameters, the depth of the mixed layer
is typically determined by the wind
speed and sea state. While relatively
low wind speed may support a weak,
shallow surface duct, such a duct
cannot support propagation of airgun
sound, which is predominantly lowfrequency. Jensen et al. (2011) provide
the following equation that determines
the cutoff frequency (frequency below
which sound will not propagate) given
the depth of an isothermal surface layer:
where f0 is the cutoff frequency in Hz
and D is the depth in meters of an
isothermal surface layer. As an example,
for a cutoff frequency to be around 100
Hz, the surface duct needs to be at least
150 m deep. In general, shallow ducts
(D <50 m) are more common, but they
are only effective waveguides for
frequencies above 530 Hz, which also
suffer high scattering loss due to the
rough sea surface under these weather
conditions.
Finally, most acoustic rays from an
airgun array are emitted at very steep
angles to be contained within the
surface duct waveguide.
For these reasons, we do not believe
surface ducts in the mid-Atlantic region,
if they exist, would contribute
noticeably to propagation for sound
emitted from airguns.
Comment: NRDC stated that NMFS
used unrealistic and non-conservative
assumptions about spreading loss,
bottom composition, and reverberation
in its propagation analysis and claimed
that the analysis does not represent the
best available science. NRDC stated that,
for propagation loss, NMFS incorrectly
assumed that normal propagation
conditions would apply, such as not
accounting for surface ducting (and
BOEM only assumed moderate surface
ducting in 3 of 21 modeled areas).
Furthermore, NRDC stated that low-
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frequency propagation along the seabed
can spread in a planar manner, and can
propagate with more efficiency than
indicated by cylindrical propagation.
Finally, NRDC asserted that NMFS
cannot accept the assumptions in three
applications (CGG, TGS, and
WesternGeco) that proposed surveys
will cover areas with soft or sandy
bottoms. NRDC claims that NOAA’s
own models indicate that there is a
likelihood of coral bottom habitat in the
survey area, and many hard-bottom
habitat areas were not modeled by
BOEM and consequently incorporated
by NMFS.
Response: Regarding sound
propagation in a surface duct, please
refer to the above response to a similar
comment from OCR. As stated earlier,
oceanographic conditions in the midAtlantic region do not support a
persistent surface duct, particularly for
low-frequency sound propagation.
Therefore, the modeling of a moderate
surface duct for airgun noise
propagation is a conservative measure.
Also as stated earlier, frequency and
launch angle of the source play a major
role in surface ducting. This information
is clearly stated by D’Spain et al. (2006)
with regard to the 2000 beaked whale
stranding in the Bahamas, i.e., that the
surface duct ‘‘. . . effectively traps mid
to high frequency sound radiated by
acoustic sources within the duct, such
as surface ship sonars . . .’’ and that
‘‘[a]t low frequencies, the sound is no
longer effectively trapped by the duct
because the acoustic wavelength. . . .
is too large in comparison to the duct
thickness.’’
NRDC’s statement that ‘‘lowfrequency propagation along the seabed
can spread in a planar manner . . . can
propagate with significantly greater
efficiency than cylindrical propagation
would indicate’’ is incorrect. Any
acoustic wave can be approximated for
plane wave propagation at sufficiently
far range (R) for a region (W) such that
W ≤ (lR)1/2, where l is the wavelength.
This plane wave approximation has no
bearing on the efficiency of sound
propagation.
Finally, substrate types for
propagation modeling are based on
grain size, porosity, and shear velocity,
etc., and ‘‘coral bottom’’ is not one of
them. In fact, the roughness of the coral
habitat would cause severe bottom loss
due to scattering. Based on published
literature, bottom types of the region are
mostly composed of sand (e.g., Stiles et
al., 2007; Kaplan, 2011). Therefore, the
use of sand and clay for propagation
modeling is appropriate. The acoustic
modeling provided by BOEM (2014a)
appropriately and reasonably accounts
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for variability in bottom composition
throughout the planned survey area.
Comment: Some groups noted that the
different approaches taken to acoustic
modeling make it difficult to compare
takes. Specifically, TGS, CGG, and
Western relied on the acoustic modeling
provided in BOEM’s PEIS, while ION
and Spectrum performed their own
modeling. In addition, Spectrum and
ION used a restricted suite of sound
velocity profiles, matching the seasons
when they intend to conduct their
planned surveys. The comment letter
from Nowacek et al. adds an assertion
that this difficulty in comparing takes is
problematic when NMFS is trying to
assess whether the activities impact
only small numbers or cause negligible
impacts, and state that they ‘‘can find no
evidence in the Notice that NMFS took
account of these significant problems
when attempting to evaluate the impacts
of the IHAs.’’
Response: As stated in a previous
response to an MMC comment, NMFS
disagrees that the different approaches
taken to sound field modeling constitute
a problem at all, much less a significant
one. BOEM’s PEIS provides a sound
analysis of expected sound fields in a
variety of propagation conditions,
including water depth, bottom type, and
season, for a representative airgun array.
ION and Spectrum conducted similar
sound field modeling, but with the
added advantage of modeling the
specific array planned for use and
limiting use of sound velocity profiles to
the time period when the survey is
planned to occur. No commenter
provided any rational basis for
disputing that these methods are
appropriate or that they used the best
available information and modeling
processes. Regardless of differences in
the sound field modeling processes, one
would not expect that the take estimates
are directly comparable, precisely
because the surveys are planned for
different locations, using different
sound sources, and, for some
companies, operating at different times
of year. We disagree the various
modeling approaches cause some
problem for conducting appropriate
negligible impact and/or small numbers
analyses; both of these findings are
appropriately made in consideration of
a given specified activity. Therefore,
comparison of the take numbers across
IHAs is not a relevant consideration. We
disagree that differences in approaches
across the applications are arbitrary. On
the contrary, we carefully evaluated
each applicant’s approaches to take
estimation and, while they are indeed
different in some respects, each
applicant uses accepted approaches.
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Unlike NRDC, we recognize that there is
no model or approach that is always the
most appropriate and that there may be
multiple approaches that may be
considered acceptable. Far from
‘‘parroting’’ the applicants’ assessments,
as NRDC implies, NMFS made
substantial changes where necessary,
including complete revision of North
Atlantic right whale take estimates for
all applicants, revision of take estimates
for all species using the best available
density data (i.e., Roberts et al., 2016)
for ION and Spectrum, and revised
assessment of potential Level A
harassment for all applicants. NMFS
strongly disagrees that ‘‘grossly
inconsistent’’ data or methods were
used for any applicant in the analyses
described herein.
Comment: One individual noted that
it is not apparent how NMFS accounted
for high-frequency sounds, which has
implications for potential takes by Level
A harassment for species that hear better
at higher frequencies. The commenter
wrote that airguns produce pulses with
most energy at low frequencies (around
10 Hz), but that these pulses contain
significant energy at frequencies up to
more than 100 kHz, claiming that highfrequency hearing specialists can be
affected at distances of 70 km or more.
The commenter cited Bain and Williams
(2006) in support of the latter claim.
Response: In considering the potential
impacts of higher-frequency
components of airgun noise on marine
mammal hearing, one needs to account
for energy associated with these higher
frequencies and determine what energy
is truly ‘‘significant.’’ Tolstoy et al.
(2009) conducted empirical
measurements, demonstrating that
sound levels (i.e., one-third-octave and
spectral density) associated with airguns
were at least 20 dB lower at 1 kHz
compared to higher levels associated
with lower frequencies (below 300 Hz).
These levels were even lower at higher
frequencies beyond 1 kHz. Thus, even
though high-frequency cetaceans may be
more susceptible to noise-induced
hearing loss at higher frequencies, it
does not mean that a source produces a
sufficiently loud sound at these higher
frequencies to induce a PTS (i.e.,
auditory injury). For example, Bain and
Williams (2006) indicated ‘‘airguns
produced energy above ambient levels
at all frequencies up to 100 kHz (the
highest frequency measured), although
the peak frequency was quite low.’’
However, a finding that airgun signals
contain energy ‘‘above ambient’’ and are
detectable at frequencies up to 100 kHz
does not mean that these levels are high
enough to result in auditory injury. The
commenter does not describe what is
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meant by ‘‘significant’’ energy, but there
is no information to suggest that these
higher-frequency noise components are
sufficient to cause auditory injury at
ranges beyond those described in Table
5.
Furthermore, Bain and Williams
(2006) focus on behavioral responses of
marine mammals to airgun surveys,
rather than on potential impacts on
hearing. Harbor porpoises, while
considered a high-frequency cetacean in
terms of hearing, are also often
categorized as a particularly sensitive
species behaviorally (i.e., consistently
responds at a lower received level than
other species; Southall et al., 2007). We
agree that harbor porpoises are more
likely to avoid loud sound sources, such
as airgun arrays, at greater distances.
However, this means that these species
are even less likely to incur some degree
of threshold shift.
Marine Mammal Densities
Comment: The MMC recommended
that NMFS require TGS and Western to
use the Roberts et al. (2016) model,
rather than the approach described
herein (see ‘‘Estimated Take’’). MMC
describes several perceived problems
with the approach taken by TGS and
Western, including that they do not
adequately account for availability and
detection biases, and that their approach
does not use the same habitat-based
approach to predicting density. Overall,
they state that it does not make sense for
applicants to use different density
estimates for the same area.
Response: Please see ‘‘Estimated
Take’’ for a full description of take
estimation methodologies used by TGS
and Western. First, we note that the
applicants did carefully consider the
Roberts et al. data in addition to other
available sources of data. In fact, these
two applicants did use the Roberts et al.
data for a group of nine species, while
devising an alternate methodology for a
separate group of seven species that did
not meet a specific threshold for
sightings data recommended by
Buckland et al. (2001). Further, these
applicants did account for bias,
correcting densities using general g(0)
values for aerial and vessel surveys for
each species as published in the
literature.
As stated below and in our Notice of
Proposed IHAs, we determined that
their alternative approach (for seven
species or species groups) is acceptable.
We recognize that there is no model or
approach that is always the most
appropriate and that there may be
multiple approaches that may be
considered acceptable. The alternative
approach used for seven species
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actually uses the most recent data, and
does so in a way that conforms with
recommended methods for deriving
density values from sightings data. We
do not believe that one or the other
approach is non-representative of the
best available science and
methodologies.
Comment: NRDC criticized NMFS’s
use of the Roberts et al. (2016) model
outputs for purposes of deriving
abundance estimates, as used in NMFS’s
small numbers analyses. NRDC states
that we should use the NMFS Stock
Assessment Report (SAR) abundance
estimates for this purpose, while
allowing that model-predicted
abundance estimates may be used for
‘‘data-deficient’’ stocks. NRDC implies
that use of model-predicted abundances
would overestimate actual abundances,
apparently based on the fact that the
density models are informed by many
years of data rather than only the most
recent year of data. Where modelpredicted abundance estimates are used,
NRDC recommends that we adjust the
averaged model outputs to the lower
bound of the standard deviation
estimated by the model for each grid
cell.
Response: The approach
recommended by NRDC is plainly
inappropriate. Comparing take estimates
generated through use of the outputs of
a density model to an unrelated
abundance estimate provides a
meaningless comparison. As explained
in our Notice of Proposed IHAs, in most
cases we compare the take estimates
generated through use of the density
outputs to the abundance predicted
through use of the model precisely to
provide a meaningful comparison of
predicted takes to predicted population.
To illustrate this, we provide the
extreme example of the Gulf of Mexico
stock of Clymene dolphin. NMFS’s three
most recent SAR abundance estimates
for this stock have fluctuated between
129 and 17,355 animals, i.e., varying by
a maximum factor of more than 100. For
most species, such fluctuations across
these ‘‘snapshot’’ abundance estimates
(i.e., that are based on only the most
recent year of survey data) reflect
interannual variations in dynamic
oceanographic characteristics that
influence whether animals will be seen
when surveying in predetermined
locations, rather than any true increase
or decline in population abundance. In
fact, NMFS’s SARs typically caution
that trends should not be inferred from
multiple such estimates, that differences
in temporal abundance estimates are
difficult to interpret without an
understanding of range-wide stock
abundance, and that temporal shifts in
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abundance or distribution cannot be
effectively detected by surveys that only
cover portions of a stock’s range (i.e.,
U.S. waters). The corresponding density
model for Gulf of Mexico Clymene
dolphins predicts a mean abundance of
11,000 dolphins. Therefore, in this
example, NRDC would have us compare
takes predicted by a model in which
11,000 dolphins are assumed to exist to
the most recent (and clearly inaccurate)
abundance estimate of 129 dolphins.
Our goal in assessing predicted takes is
to generate a meaningful comparison,
which is accomplished in most cases
through use of the model-predicted
abundance.
SAR abundance estimates have other
issues that compromise their use in
creating meaningful comparisons here.
As in the example above, use of
multiple years of data in developing an
abundance estimate minimizes the
influence of interannual variation in
over- or underestimating actual
abundance. Further, SAR abundance
estimates are typically underestimates
of actual abundance because they do not
account for availability bias due to
submerged animals—in contrast,
Roberts et al. (2016) do account for
availability bias and perception bias on
the probability of sighting an animal—
and because they often do not provide
adequate coverage of a stock’s range.
The SAR for the Canadian East Coast
stock of minke whales provides an
instructive example of the latter. In the
2015 SARs, NMFS presented a best
abundance estimate of 20,741 minke
whales, reflecting data that provided
adequate (but not complete) coverage of
the stock’s range. In the 2016 SARs,
NMFS claims an abundance estimate of
2,591 whales for this same stock (albeit
with caveats) simply because the survey
data covering the Canadian portion of
the range was no longer included in
determining the best abundance
estimate. We assume that again, based
on this comment, NRDC would have us
compare the minke whale take estimates
to this plainly incomplete abundance
estimate.
NRDC appears to claim that the SARs
are an appropriate representation of
‘‘actual’’ abundance, whereas the
Roberts et al. (2016) predictions are not.
NRDC also appears to claim, without
substantiation, that an abundance
estimate derived from multiple years of
data would typically overestimate actual
abundance. However, these estimates
are not directly comparable—not
because one represents a ‘‘snapshot,’’
while one represents multiple years of
data, but because one does not correct
for one or more known biases against
the probability of observing animals
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during survey effort, while the other
does. Because of this important caveat,
NMFS’s SAR abundance estimates
should not be considered ‘‘actual’’
abundance more than any other
accepted estimate. Therefore, when
multiple estimates of a stock’s
abundance are available, they should be
evaluated based on quality, e.g., does
the estimate account for relevant biases,
does it best cover the stock’s range, does
it minimize the effect of interannual
variability, and, importantly, should
provide a meaningful comparison. In
summary, NRDC’s comment reflects an
inaccurate interpretation of the available
information, and NMFS strongly
disagrees with the recommended
approach.
Take Estimates
Comment: The Associations
(representing oil and gas industry
interests) state that ‘‘NMFS substantially
overestimates the number of incidental
takes predicted to result’’ from the
specified activities. The comment goes
on to discuss the ‘‘biased modeling that
is intentionally designed to overestimate
take’’ provided in BOEM’s 2014 PEIS.
Other industry commenters repeat these
points verbatim.
Response: The Associations’
statement that NMFS has substantially
overestimated takes is incorrect. First, in
large part the take estimates are those
presented by the applicants (although in
some cases NMFS has made changes to
the presented estimates in accordance
with the best available information).
Second, two applicants conducted their
own independent sound field modeling,
which NMFS accepted. In fact, BOEM
and these two applicants followed best
practices and used the best available
information in conducting state-of-thescience sound field modeling. The
Associations’ complaints include no
substantive recommendations for
improvement.
NMFS participated in development of
the acoustic modeling through its status
as a cooperating agency in development
of BOEM’s PEIS. We strongly disagree
with the Associations’ characterization
of the modeling conducted by BOEM
and with the BOEM statements cited by
the Associations. While the modeling
required that a number of assumptions
and choices be made by subject matter
experts, some of these are purposely
conservative to minimize the likelihood
of underestimating the potential impacts
on marine mammals represented by a
specified level of survey effort. The
modeling effort incorporated
representative sound sources and
projected survey scenarios (both based
on the best available information
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obtained by BOEM), physical and
geological oceanographic parameters at
multiple locations within U.S. waters of
the mid- and south Atlantic and during
different seasons, the best available
information regarding marine mammal
distribution and density, and available
information regarding known behavioral
patterns of the affected species. Current
scientific information and state-of-theart acoustic propagation and animal
movement modeling were used to
reasonably estimate potential exposures
to noise. NMFS’s position is that the
results of the modeling effort represent
a conservative but reasonable best
estimate. These comments provide no
reasonable justification as to why the
modeling results in overestimates of
take, instead seemingly relying on the
mistaken notion that real-time
mitigation would somehow reduce
actual levels of acoustic exposure, and
we disagree that ‘‘each of the inputs is
purposely developed to be
conservative’’—indeed, neither the
Associations nor BOEM provide any
support for the latter statement.
Although it may be correct that
conservativeness accumulates
throughout the analysis, the
Associations do not adequately describe
the nature of conservativeness
associated with model inputs or to what
degree (either quantitatively or
qualitatively) such conservativeness
‘‘accumulates.’’
Comment: One individual stated that
NMFS should consider how ‘‘animal
behavioral response can condition
exposure,’’ noting that behavioral
responses may result in effects to the
potential amount and intensity of take.
We believe the commenter is suggesting
that the way any specific animal moves
through the water column in initial
response to the sound can change the
manner in which they are subsequently
further exposed to the sound.
Response: The commenter seemingly
indicated that some species should be
expected to dive downwards rather than
exhibit lateral avoidance. While we
agree that this may occur, we do not
agree that this would result in an
increase in intensity of take—and such
an occurrence could not by definition
result in an increase in the absolute
amount of take, as the animal in
question would already be considered
‘‘taken.’’ Given relative motion of the
vessel and the animal, there is no
evidence to support that avoidance of
the noise through downward, rather
than lateral, movement would result in
a meaningful increase in the duration of
exposure, as implied by the commenter.
Comment: The Associations stated
that it is unclear whether the take
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estimates include repeated exposures
and that, if so, the estimates do not
identify the number of repeated
exposures, instead presenting a total
number of estimated exposures by
species. The Associations state that
NMFS must perform additional analysis
to identify the actual number of
individual marine mammals that may be
incidentally taken.
Response: The take estimates
presented in our Notice of Proposed
IHAs, and those shown in Table 6 of
this notice, represent total estimated
instances of exposure. We agree with
the Associations that an understanding
of the numbers of individuals affected
by the total estimated instances of
exposure is relevant, both for the small
numbers analysis (a small numbers
analysis is appropriately made on the
basis of individuals taken rather than
total takes, when such information is
available) but also for assessing
potential population-level impacts in a
negligible impact analysis. We also
agree that this information is relevant to
these analyses and important to use,
when available. In fact, one applicant
(TGS) provided an analysis of
individuals exposed; following review
of public comments and re-evaluation of
TGS’s application, we considered this
information in our small numbers
analysis for TGS. However, without
such information, an assumption that
the total estimated takes represent takes
of different individuals is acceptable in
that it represents a conservative estimate
of the total number of individuals taken
made in the absence of sufficient
information to differentiate between
individuals exposed and instances of
exposure, and is also generally a
reasonable approach given the large,
dispersed spatial scales over which the
surveys operate. The MMPA does not
require that NMFS undertake any such
analysis and, in fact, sufficient
information is not typically available to
support such an analysis.
Comment: NRDC states that masking
results in take of marine mammals, and
that NMFS must account for this in its
take estimates.
Response: We addressed our
consideration of masking in greater
detail in a previous response. We
acknowledge that masking may impact
marine mammals, particularly baleen
whales, and particularly when
considered in the context of the full
suite of regulated and unregulated
anthropogenic sound contributions
overlaying an animal’s acoustic habitat.
However, we do not agree that masking
effects from the incremental noise
contributions of individual activities or
sound sources necessarily, or typically,
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rise to the level of a take. While it is
possible that masking from a particular
activity may be so intense as to result
in take, we have no information
suggesting that masking of such
intensity and duration would occur as a
result of the specified activities. As
described in our previous comment
response, potential effects of a specified
activity must be accounted for in a
negligible impact analysis, but not all
responses or effects result in take nor
are those that do always readily
quantified. In this case, while masking
is considered in the analysis, we do not
believe it will rise to the level of take
in the vast majority of exposures.
However, specifically in the case of
these five surveys, in the unanticipated
event that any small number of masking
incidents did rise to the level of a take,
we would expect them to be accounted
for in the quantified exposures above
160 dB. Given the short duration of
expected noise exposures, any take by
masking in the case of these surveys
would be most likely to be incurred by
individuals either exposed briefly to
notably higher levels or those that are
generally in the wider vicinity of the
source for comparatively longer times.
Both of these situations would be
captured in the enumeration of takes by
Level B harassment, which is based on
exposure at or above 160 dB, which also
means the individual necessarily spent
a comparatively longer time in the
adjacent area ensonified below 160 dB,
but in which masking might occur if the
exposure was notably longer.
Comment: NRDC, the MMC, and
others state that NMFS’s Level A
harassment exposure analysis contains
potentially significant errors. The MMC
recommends that NMFS (1) provide
company-specific Level A harassment
zones for each functional hearing group,
and (2) re-estimate the numbers of Level
A harassment. NRDC states that, by
relying on BOEM’s 2014 PEIS, NMFS
did not use the best available science,
e.g., use of earlier density data (DoN,
2007) rather than Roberts et al. (2016).
NRDC goes on to cite as an additional
flaw of the analysis that ‘‘NMFS
assumes that auditory take estimates for
high-frequency cetaceans depend on the
exposure of those species to single
seismic shots . . . even though the
weighted auditory injury zone for highfrequency cetaceans extends as far as 1.5
kilometers [ . . . . ] The size of the
injury zone suggests that NMFS’
assumption about high-frequency
cetaceans is incorrect, and that the
agency should calculate auditory injury
by applying both the peak-pressure
threshold and a metric that accounts for
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exposure to multiple shots (e.g., the
cumulative sound energy thresholds
included in NMFS’ guidance).’’
Response: As described in ‘‘Estimated
Take,’’ NMFS revised the approach to
assessing potential for auditory injury,
and associated authorization of take by
Level A harassment. NMFS disagrees
that the prior approach for the proposed
IHAs contained ‘‘significant errors.’’ As
stated in our Notice of Proposed IHAs,
we used the information available to us
and made reasonable corrections to
account for applicant-specific
information. However, following review
of public comments, we determined it
appropriate to re-evaluate the analysis
and subsequently revised our approach
as described in ‘‘Estimated Take.’’ This
revised approach is simplified in its use
of the available information while
providing a reasonable assessment of
the likely potential for auditory injury,
and has the advantage of not relying on
the BOEM PEIS results. While the PEIS
results remain a reasonable assessment
of potential effects from a programmatic
perspective, and were based on the best
available cetacean density information
at the time the analyses were conducted,
they do not use the best cetacean
density information currently available
(Roberts et al., 2016), and also did not
recognize that the potential for Level A
harassment occurrence for midfrequency cetaceans is discountable
(described in detail in ‘‘Estimated
Take’’). However, the second portion of
NRDC’s comment is incorrect: The peak
pressure injury zones referred to by
NRDC as extending as far as 1.5 km are
not weighted for hearing sensitivity, as
it is inappropriate to do so for exposure
to peak pressure received levels (NMFS,
2018). Applicant-specific zones are
shown in Table 5; all zones based on
accumulation of energy are very small
for high-frequency cetaceans. It is
unclear what NRDC’s recommendation
to ‘‘calculate auditory injury by
applying both the peak-pressure
threshold and a metric that accounts for
exposure to multiple shots’’ means, as
the former is predominant for highfrequency cetaceans, while zones based
on the latter are essentially non-existent.
As recommended by the MMC, we have
provided company-specific Level A
harassment zones for each functional
hearing group (see Table 5).
Comment: One individual asserted
that NMFS fails to account for
variability in group size and distribution
of various species, stating that while the
best estimate of take may be a fraction
of an individual in practice either no
individuals will be taken, or one or
more groups will be taken. The
individual suggested that NMFS should
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decide whether it may authorize one or
more large groups, rather than estimates
of a fraction of an individual.
Response: We agree with this
comment. Accordingly, and as
described in our Notice of Proposed
IHAs, we did not propose to authorize
take less than the average group size for
any species. In fact, our take
authorization for a group of species
deemed ‘‘rare’’ was based entirely on an
assumption of one encounter with a
group, i.e., we authorize take equating to
one average group size.
Comment: NRDC asserts that NMFS
fails to account for forms of injury that
are reasonably anticipated, stating that
permanent hearing loss (i.e., Level A
harassment) may occur through
mechanisms other than PTS, and that
behaviorally-mediated injury may occur
as a result of exposure to airgun noise.
NRDC states that NMFS must account
for these mechanisms in its assessment
of potential injury.
Response: NMFS is aware of the work
by Kujawa and Liberman (2009), which
is cited by NRDC. The authors report
that in mice, despite completely
reversible threshold shifts that leave
cochlear sensory cells intact, there were
synaptic level changes and delayed
cochlear nerve degeneration. However,
the large threshold shifts measured (i.e.,
maximum 40 dB) that led to the
synaptic changes shown in this study
are within the range of the large shifts
used by Southall et al. (2007) and in
NMFS’s technical guidance to define
PTS onset (i.e., 40 dB). It is unknown
whether smaller levels of temporary
threshold shift (TTS) would lead to
similar changes or what may be the
long-term implications of irreversible
neural degeneration. The effects of
sound exposure on the nervous system
are complex, and this will be reexamined as more data become
available. It is important to note that
NMFS’s technical guidance
incorporated various conservative
factors, such as a 6–dB threshold shift
to represent TTS onset (i.e., minimum
amount of threshold shift that can be
differentiated in most experimental
conditions); the incorporation of
exposures only with measured levels of
TTS (i.e., did not incorporate exposures
where TTS did not occur); and assumed
no potential of recovery between
intermittent exposures. NMFS disagrees
that consideration of likely PTS is not
sufficient to account for reasonably
expected incidents of auditory injury.
There is no conclusive evidence that
exposure to airgun noise results in
behaviorally-mediated forms of injury.
Behaviorally-mediated injury (i.e., mass
stranding events) has been primarily
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associated with beaked whales exposed
to mid-frequency naval sonar. Tactical
sonar and the alerting stimulus used in
Nowacek et al. (2004) are very different
from the noise produced by airguns.
One should therefore not expect the
same reaction to airgun noise as to these
other sources.
Comment: TGS recommends that
NMFS (1) recalculate take estimates to
account for mitigation; (2) remove take
estimates associated with the
disallowed use of a mitigation gun; and
(3) ensure that we do not double-count
takes when considering takes by both
Level A and Level B harassment.
Response: We agree with these
recommendations and have done as
requested; please see ‘‘Estimated Take’’
for further detail. We do note that, with
regard to accounting for mitigation in
calculating take estimates, our analysis
involved only an accounting of take
avoided for certain species as a result of
the implementation of time-area
restrictions. We did not attempt to
account for the potential efficacy of
other mitigation requirements in
avoiding take.
Comment: The Florida Department of
Environmental Protection (FLDEP)
wrote that NMFS needs to be cautious
in relying on the efficacy of mitigation
measures to estimate take by Level A
harassment, particularly with regard to
North Atlantic right whales. They noted
additional information on the
effectiveness of proposed mitigation is
necessary.
Response: While we agree with the
commenters that caution is warranted in
assuming that standard mitigation
measures, such as shutdowns, will be
effective in avoiding Level A
harassment, we note that our estimation
of likely take by Level A harassment
does not substantively rely on such
assumptions. As described in
‘‘Estimated Take,’’ auditory injury of
mid-frequency cetaceans is highly
unlikely, for reasons unrelated to
mitigation. In estimating likely Level A
harassment of high-frequency cetaceans,
we did not consider mitigation at all, as
the instantaneous exposures expected to
result in auditory injury are amenable to
a straightforward quantitative estimate.
However, our Level A harassment take
estimates for low-frequency cetaceans
are based on a more qualitative analysis
that does consider the implementation
of mitigation, as is appropriate. We do
not assume in any case that real-time
mitigation would be totally effective in
avoiding such instances, but for the
theoretical injury zone sizes considered
here for low-frequency cetaceans, which
are based on the accumulation of
energy, it is reasonable to assume that
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large whales may be observed when
close to the vessel. Therefore, shutdown
may be implemented and accumulation
of energy halted such that actual
instances of injury should not be
considered likely. Our estimated
instances of Level A harassment for lowfrequency cetaceans consider the
expected frequency of encounter for
different species and the expectation
that mitigation will be effective in
avoiding some instances of Level A
harassment, but also the likelihood that
for some species that would be
encountered most frequently, some
instances of Level A harassment are
likely unavoidable. Specifically for the
right whale, we primarily consider that
our required time-area restriction will
avoid most acute exposures of the
species (or that comparable protection
will be achieved through
implementation of a NMFS-approved
mitigation and monitoring plan at
distances between 47–80 km offshore)
(as shown in the very low numbers of
estimated take by Level B harassment,
which account for the time-area
restriction). Given such a low assumed
encounter rate, the likelihood of Level A
harassment for the species is correctly
considered discountable. Please see our
discussion in ‘‘Estimated Take’’ for
further detail.
Comment: NRDC asserts that NMFS
has failed to account for the effects of
stress on marine mammals.
Response: As NRDC acknowledges,
we addressed the available literature
regarding potential impacts of stress
resulting from noise exposure in marine
mammals. As described in that
discussion, stress responses are
complicated and may or may not have
meaningful impacts on marine
mammals. NRDC implies that NMFS
must (1) enumerate takes resulting from
stress alone and (2) specifically address
stress in its negligible impact analyses.
The effects of stress are not
straightforward, and there is no
information available to inform an
understanding of whether it is
reasonably likely that an animal may
experience a stress response upon noise
exposure that would not be accounted
for in NMFS’s enumeration of takes via
exposure to noise exceeding 160 dB.
NRDC provides no useful information as
to how such an analysis might be
carried out. With regard to NMFS’s
negligible impact analyses, we believe
that the potential effects of stress are
addressed and subsumed within
NMFS’s considerations of magnitude of
effect and likely consequences.
Similarly, NRDC provides no
justification as to why stress would
appropriately be considered separately
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in these analyses, and no useful
recommendation as to how to do so, if
appropriate. We believe we have
appropriately acknowledged the
potential effects of stress, and that these
potential effects are accounted for
within our overall assessment of
potential effects on marine mammals.
Comment: The MMC recommends
that NMFS (1) determine whether the
specific animat density used by
Spectrum is appropriate and (2)
depending on the outcome of that
assessment, either authorize
uncorrected take numbers from
Spectrum’s application, or re-estimate
the numbers of Level B harassment
takes using a higher animat density.
Response: We appreciate the MMC’s
consideration of this issue. Following
evaluation of the comment, we confirm
that the animat density used by
Spectrum is appropriate. As stated by
Marine Acoustics, Inc. (MAI)—which
has years of experience in the field of
acoustic modeling and performed the
modeling for Spectrum (as well as ION)
according to state-of-the science best
practices—the modeled animat density
value was determined through a
sensitivity analysis that examined the
stability of the predicted estimate of
exposure levels as a function of animat
density. The modeled density was
determined to accurately capture the
full distributional range of probabilities
of exposure for the proposed survey,
and is therefore appropriate. In
describing the original modeling, MAI
stated that in most cases the animat
density represented a higher density of
animats in the simulation than occurs in
the real world. This ‘‘over-population’’
allowed the calculation of smoother
distribution tails, and in the final
analysis all results were normalized
back to the actual estimated density for
the species or group in question. This
remains the case when using the revised
density estimates from Roberts et al.
(2016). We disagree with MMC’s
contention that the mitigation
assumptions used by Spectrum in
modeling Level B harassment takes were
inappropriate; therefore, we retain the
estimates proposed for authorization (as
modified using the newer Roberts et al.
(2016) density values).
Comment: The FLDEP stated that
NMFS should account for uncertainty in
take estimates, including uncertainty
about marine mammal density, sound
propagation models, and auditory
thresholds, and that these factors should
‘‘all manifest as uncertainty around take
estimates and be reported in and
considered for IHAs.’’
Response: We agree with the
commenter that it would be useful to
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understand the degree of confidence in
take estimates through some measure of
uncertainty around the estimate, and
that uncertainty can accrue through all
of the mentioned aspects of the take
estimation process. However, we believe
that the take estimates are reasonable
best estimates. Measuring uncertainty
around a take estimate is not something
that has been accomplished in the past,
and the commenter provides no
recommendation as to how they believe
this should be done.
Comment: The NAMA stated that an
IHA should be revoked if it is found that
a take by Level A harassment has
occurred.
Response: Level A harassment, which
is defined as an act with the potential
to injure a marine mammal, may be
authorized through an IHA, as we have
done here.
Comment: The New York State
Department of Environmental
Conservation stated that the amount of
takes by Level A harassment proposed
for humpback whales is considerable
when considered in context of the
ongoing UME, and that NMFS should
give more consideration to this concern.
Response: We have considered the
ongoing effects of the humpback whale
UME in our evaluation. We also
reiterate that Level A harassment refers
to injury, and therefore cannot be
directly equated to serious injury or
mortality, and further that the estimated
takes by Level A harassment likely
represent only onset of mild PTS.
However, separately, we have revised
our estimates of Level A harassment for
all species (see ‘‘Estimated Take’’),
resulting in much lower estimates for
humpback whales. The revised results
of this analysis should obviate the
concern expressed here.
Comment: OCR stated that NMFS
should consider the potential use of
ancillary noise sources (e.g., side-scan
or multibeam bottom profiling sonars)
in estimating take, and notes that these
sources have been associated with
marine mammal strandings.
Response: We did consider this
potential avenue of acoustic exposure.
We understand that, generally, vessel
operators plan to use standard
navigational echosounders (single beam)
operated at relatively high frequencies
(>18 kHz). In addition, it is possible that
some applicants may use a low-level
acoustic pinger to help position their
towed gear. It is possible that some
marine mammals could detect and react
to signals from these sources (although
this is less likely for low-frequency
cetaceans, and these species would not
likely detect signals from these systems
if they are operated above 35 kHz).
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However, the vast majority of the time
echosounders would be in use, so
would airguns which have much higher
source levels and are expected to result
in more severe reactions than any
associated with echosounders
specifically. We would expect that in
most cases, any response would be to
airguns rather than the echosounder
itself. We recognize that there would be
limited use of echosounders or pingers
while airguns are not active, for
example, when vessels are in transit
from port to areas where surveys will
occur. However, we do not believe this
results in meaningful exposure to
marine mammals since, given the lower
source levels and higher frequencies of
echosounders and pingers, animals
would need to be very close to the
transducer to receive source levels that
would produce a behavioral response
(Lurton, 2016), much less one that
would result in a response of a degree
considered to be take.
In extreme circumstances, some
echosounders and pingers may also
have the potential to cause injury, and
in one case evidence indicates such a
system likely played a contributing role
in a cetacean stranding event. However,
injury (or any threshold shift) is even
less likely than behavioral responses
since animals would need to be even
closer to the transducer for these to
occur. It is also important to note that
the system implicated in the stranding
event was a lower-frequency (12–kHz),
higher-power deepwater mapping
system; typical navigational systems,
including those that the applicants here
would use, would have lower potential
to cause similar responses. Kremser et
al. (2005) concluded the probability of
a cetacean swimming through the area
of exposure when such sources emit a
pulse is small, as the animal would have
to pass at close range and be swimming
at speeds similar to the vessel in order
to receive multiple pulses that might
result in sufficient exposure to cause
TTS. This finding is further supported
by Boebel et al. (2005), who found that
even for echosounders with source
levels substantially higher than those
proposed here, TTS is only possible if
animals pass immediately under the
transducer. Burkhardt et al. (2013)
estimated that the risk of injury from
echosounders was less than three
percent that of vessel strike, which is
considered extremely unlikely to occur
such that it is discountable. In addition,
modeling by Lurton (2016) of multibeam
echosounders indicates that the risk of
injury from exposure to such sources is
negligible.
Navigational echosounders are
operated routinely by thousands of
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vessels around the world, and to our
knowledge, strandings have not been
correlated with their use. The
echosounders and pinger proposed for
use differ from sonars used during naval
operations, which generally have higher
source levels, lower frequencies, a
longer pulse duration, and more
horizontal orientation than the more
downward-directed echosounders. The
sound energy received by any
individuals exposed to an echosounder
during the proposed seismic survey
activities would be much lower relative
to naval sonars, as would be the
duration of exposure. The area of
possible influence for the echosounders
is also much smaller, consisting of a
narrow zone close to and below the
source vessels as described previously
for TTS and PTS. Because of these
differences, we do not expect the
proposed echosounders and pinger to
contribute to a marine mammal
stranding event. In summary, any effects
that would be considered as take are so
unlikely to occur as a result of exposure
from ancillary acoustic sources as to be
considered discountable.
Marine Mammal Protection Act—
General
Comment: Several groups indicated a
belief that NMFS’s proposal to issue the
five IHAs contradicts Congressional
intent behind the MMPA. For example,
Clean Ocean Action (COA) stated that
issuance of the IHAs would be
incompatible with the original intent of
the MMPA. Sea Shepherd Legal stated
that the legislative history of the MMPA
makes clear that the precautionary
principle must be applied and bias must
favor marine mammals, and opines that
NMFS’s proposed issuance of the IHAs
‘‘undermines the MMPA’s prioritization
of conservation.’’
Response: NMFS disagrees that these
actions contradict any requirement of
the MMPA or are contrary to
Congressional intent as expressed in
relevant provisions of the statute.
Neither the MMPA nor NMFS’s
implementing regulations include
references to, or requirements for, the
precautionary approach, nor is there a
clear, agreed-upon description of what
the precautionary approach is or would
entail in the context of the MMPA or
any specific activity. Nevertheless, the
MMPA by nature is inherently
protective, including the requirement to
mitigate to the lowest level practicable
(‘‘least’’ practicable adverse impacts, or
‘‘LPAI,’’ on species or stocks and their
habitat). This requires that NMFS assess
measures in light of the LPAI standard.
To ensure that we fulfill that
requirement, NMFS considers all
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potential measures (e.g., from
recommendations or review of available
data) that have the potential to reduce
impacts on marine mammal species or
stocks, their habitat, or subsistence uses
of those stocks, regardless of whether
those measures are characterized as
‘‘precautionary.’’
Comment: Several groups stated that
the duration of the public comment
period was inadequate. A group of
fourteen U.S. Senators urged NMFS to
extend the comment period to at least
150 days (30 for each applicant). They
wrote that publishing the notice of
proposed IHAs had little notice, a short
comment period, and no public
hearings, adding that the notice of
proposed IHAs addresses two
applications that NMFS had not
previously made available for public
review. Some commenters decried what
they perceived as a lack of stakeholder
outreach. Multiple groups requested
that NMFS hold public hearings in the
affected regions about the proposed
IHAs and their potential impacts.
Response: NMFS has satisfied the
requirements of the MMPA, which
requires only that NMFS publish notice
of a proposed authorization and request
public comment for a period of 30 days.
In fact, NMFS exceeded this
requirement by extending the public
comment period by 15 days, for a total
period of 45 days. By publishing a joint
notice of the five proposed IHAs rather
than five separate concurrent notices,
NMFS provided for more efficient
public review and comment on these
substantially similar actions. Although
NMFS acknowledges that these are five
separate actions, there is no requirement
to provide for consecutive review
periods (i.e., five 30-day periods totaling
150 days). Although not required,
NMFS in 2015 published a notice of
receipt of applications received to afford
opportunity for public review and
comment. Therefore, NMFS provided an
opportunity for review of the
applications for 30 days followed by a
45-day review of the proposed IHAs, for
a total of 75 days of review—far above
what is required by the MMPA. As
stated earlier in this document, the
additional two applications received
following the 2015 review were
substantially similar to those offered for
review, and we determined that
publishing a notice of their receipt
would not provide any additional useful
information.
Overall, we believe that there has
been sufficient opportunity for public
engagement with regard to the proposed
surveys, through opportunities
associated with NMFS’s consideration
of the requested IHAs under the MMPA
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and those associated with BOEM’s
consideration of requested permits
under OCSLA (or through other
associated statutory requirements). The
public, coastal states, and other
stakeholders have had substantial
opportunity for involvement via
processes related to the Coastal Zone
Management Act (CZMA), NEPA,
OCSLA, and the MMPA. In 2014, BOEM
completed their PEIS, with NOAA
acting as a cooperating agency in
development of the PEIS. During EIS
scoping, BOEM offered two separate
comment periods and held seven public
meetings in coastal states. The draft
PEIS was made available for public
review and comment for 94 days. Public
hearings were held in eight coastal
states. Subsequently, the final PEIS was
made available for public comment for
90 days prior to BOEM’s issuance of a
Record of Decision. After completion of
the 2014 PEIS, BOEM made all
geophysical survey permit requests
available for public review and
comment for 30 days. With NMFS’s
participation, BOEM subsequently held
eight open house meetings in coastal
states for the public to learn more about
the proposed surveys and to provide
input to the permitting process. In
addition, NOAA and BOEM engaged
with coastal states as required by the
CZMA federal consistency provision.
Comment: NRDC states that the
specified activities have the potential to
kill and seriously injure marine
mammals, and that NMFS cannot
therefore authorize the requested
incidental take via an IHA. NRDC
specifically contends that behavioral
disturbance (i.e., Level B harassment)
can result in more severe outcomes (i.e.,
Level A harassment or serious injury or
mortality) through secondary effects,
and that NMFS must consider this.
Similarly, Oceana and other
commenters suggest that Level A
harassment (i.e., auditory injury) cannot
be authorized via an IHA, as it is
equivalent to serious injury or mortality.
In this same vein, commenters relate
Level A harassment to potential
biological removal (PBR) levels, a metric
used to evaluate the significance of
removals from a population (i.e., serious
injury or mortality).
Response: We strongly disagree that
mortality or serious injury are
reasonably anticipated outcomes of
these specified activities, and the
commenters do not provide compelling
evidence to the contrary. Instead,
commenters present speculative
potentialities, including the contention
that behavioral disturbance will lead to
heightened risk of strike or predation.
Moreover, the specific example given by
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NRDC—that the migratory path for right
whales lies ‘‘in the middle of the’’
survey area—is plainly incorrect. The
migratory path for right whales lies
along the continental shelf (Schick et
al., 2009; Whitt et al., 2013; LaBrecque
et al., 2015), whereas the survey area
extends out to 350 nmi from shore, with
most survey effort planned for waters
where right whales do not occur (i.e.,
waters greater than 1,500 m deep;
Roberts et al., 2017). More importantly,
we require that applicants maintain a
minimum standoff distance of 90 km
from shore from November through
April (or that comparable protection be
achieved through implementation of a
NMFS-approved mitigation and
monitoring plan at distances between
47–80 km offshore), encompassing the
expected migratory path and season and
obviating any concern regarding
potential secondary effects on migrating
right whales.
Separately, section 101(a)(5)(D) of the
MMPA, which governs the issuance of
IHAs, indicates that the ‘‘the Secretary
shall authorize . . . . taking by
harassment [ . . . . ]’’ The definition of
‘‘harassment’’ in the MMPA clearly
includes both Level A and Level B
harassment.
Last, PBR is defined in the MMPA (16
U.S.C. 1362(20)) as ‘‘the maximum
number of animals, not including
natural mortalities, that may be removed
from a marine mammal stock while
allowing that stock to reach or maintain
its optimum sustainable population’’
and is a measure to be considered when
evaluating the effects of mortality or
serious injury on a marine mammal
species or stock. Level A harassment is
not equivalent to serious injury and
does not ‘‘remove’’ an individual from
a stock. Therefore, it is not appropriate
to use the PBR metric to directly
evaluate the effects of Level A
harassment on a stock in the manner
suggested by commenters.
Comment: ION expressed concern
regarding proposed IHA language
indicating that ‘‘taking of any other
species of marine mammal is prohibited
and may result in the modification,
suspension, or revocation’’ of an IHA,
requesting that NMFS remove this
language. Applicants also expressed
concern about not being able to avail
themselves of the IHAs while they are
effective.
Response: The referenced language is
standard text in issued IHAs, which
acknowledges that, while unlikely and
unexpected, species for which take is
not authorized may be observed and
unintentionally taken. Absent
extenuating circumstances, it is unlikely
that such an occurrence would result in
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the suspension or revocation of an IHA.
Rather, in the event that an observation
is made of an unusual species for which
take is not authorized, we would
consider whether it is likely that the
take warrants a modification of the IHA
in order to include future take
authorization for that species, or
whether it is more likely that the
observation would not occur again.
NMFS has also included a provision for
an IHA holder to request suspension of
the IHA when operations must cease for
reasons outside the holder’s control,
excluding certain circumstances, for a
limited period.
Least Practicable Adverse Impact
Comment: NRDC believes NMFS
relies on a ‘‘flawed interpretation’’ of
the least practicable adverse impact
standard. They state that NMFS (1)
wrongly imports a population-level
focus into the standard, contrary to the
‘‘clear’’ holding of the Ninth Circuit in
NRDC v. Pritzker; (2) inappropriately
‘‘balances’’ or weighs effectiveness
against practicability without sufficient
analysis, counter to Pritzker, using the
seasonality of Area #5 and NMFS’s core
abundance approaches as examples; and
(3) must evaluate measures on the basis
of practicability (which connotes
feasibility), not practicality (which
connotes usefulness)—and evaluating
on the basis of practicality would be
arbitrary and capricious.
Response: We carefully evaluated the
Ninth Circuit’s opinion in Pritzker and
believe we have fully addressed the
Court’s concerns. Our discussion of the
least practicable adverse impact
standard in the section entitled
‘‘Mitigation’’ explains why we believe a
population focus is a reasonable
interpretation of the standard. With
regard to the second point, we disagree
that the Ninth Circuit’s opinion requires
such a mechanical application of the
factors that must be considered in
assessing mitigation options. Finally, we
agree with the commenter that we must
evaluate measures on the basis of
practicability, and for these IHAS we
have done so. Our assessment of
measures for practicability looked at
appropriate considerations, as
demonstrated by our discussion in this
Notice. This included cost and impact
on operations. We note that although
not directly relevant for these IHAs, in
the case of a military readiness activity,
practicality of implementation is
explicitly part of the practicability
assessment. Thus, the two concepts are
not entirely distinct.
Comment: In determining whether
proposed IHAs meet the least
practicable adverse impact (LPAI)
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standard, the MMC recommends that
NMFS (1) identify the potential adverse
impacts that it has identified and is
evaluating; (2) specify what measures
might be available to reduce those
impacts; and (3) evaluate whether such
measures are practicable to implement.
The MMC further suggests that NMFS
provided ‘‘virtually no analysis to
support’’ our conclusions.
Response: The MMC identifies a
specific manner in which it
recommends NMFS consider applicable
factors in its least practicable adverse
impact analysis, however, NMFS has
clearly articulated the agency’s
interpretation of the LPAI standard and
our evaluation framework in the
‘‘Mitigation’’ section of this notice.
NMFS disagrees that analysis was not
provided to support our least
practicable adverse impact findings.
Specifically, NMFS identifies the
adverse impacts that it is considering in
the LPAI analysis, and comprehensively
evaluates an extensive suite of measures
that might be available to reduce those
impacts (some of which are adopted and
some that are not) both in the context
of their expected ability to reduce
impacts to marine mammal species or
stocks and their habitat, as well as their
practicability (see ‘‘Mitigation’’ and
‘‘Negligible Impact Analyses and
Determinations’’ sections).
Comment: TGS recommended that
NMFS ‘‘model how many shut-down
and delay actions would be expected for
a survey’’ in evaluating practicability,
suggesting that ‘‘animat modeling could
be used to accomplish this estimate.’’
Response: NMFS is not aware of data
sources that would appropriately inform
such an analysis, and does not agree
that such an analysis is either practical
or necessary. Moreover, we believe we
have addressed the commenter’s
concern by removing a number of
shutdown measures (in response to
other public comments) that we
determined were likely ineffective and/
or impracticable or otherwise
unwarranted, thus minimizing the
accumulation of potential for shutdown
and delay actions. We also note that
seismic operators have successfully and
practicably implemented shutdowns in
multiple regions, both in the United
States and in other countries where
seismic mitigation protocols have been
prescribed, and that larger shutdown
zones have previously been required of
operators in the U.S. Arctic as well as
for research seismic cruises, without
any known practicability issues. We
have appropriately accounted for issues
related to practicability in our analysis
of the appropriate suite of required
mitigation measures.
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Negligible Impact
Comment: As described briefly in a
previous comment and response, NRDC
asserts that NMFS should conduct a
combined negligible impact analysis for
all five specified activities, in
consideration of the aggregate take
across all five surveys in the same
geographical region, over the same
period of time, and with ‘‘substantially
similar impacts on marine mammals.’’
NRDC states that NMFS’s failure to do
so does not meet our legal obligations
under the MMPA and is ‘‘contrary to
common sense and principles of sound
science.’’ Other commenters offer
similar comments. NRDC cites to
legislative history that indicates
‘‘specified activity’’ includes all actions
for which ‘‘the anticipated effects will
be substantially similar.’’ H.R. Rep. No.
97–228 (Sept. 16, 1981), as reprinted in
1981 U.S.C.C.A.N. 1458, 1469. Further,
NRDC cites to NMFS’s 1989
implementing regulations as further
evidence that NMFS must ‘‘evaluate the
impacts resulting from all persons
conducting the specified activity, not
just the impacts from one entity’s
activities.’’ Based on this, NRDC argues
that NMFS must make a finding that the
authorized activity—which includes all
five IHA applications—will have a
negligible impact on the affected species
or stocks.
Response: We considered five distinct
specified activities and, therefore,
performed five distinct negligible
impact analyses. As we said in a
previous response to comment, we
believe the ‘‘specified activity’’ for
which incidental take coverage is being
sought under section 101(a)(5)(D) is
appropriately defined and described by
the applicant. Here there are five
specified activities, with a separate
applicant for each.
Although NRDC’s comment correctly
cites the pertinent language from section
101(a)(5)(D) (which was enacted in
1994), it refers to legislative history from
1981 in support of its argument. But that
legislative history corresponds to
Congress’ enactment of the provision for
incidental take regulations. Because the
IHA provisions were added in 1994,
citations from the 1981 legislative
history cannot accurately be referenced
as statements made ‘‘in enacting this
provision.’’ More substantively, the
sentence from which NRDC quotes was,
in our view, for the purpose of
instructing the agencies to avoid
promulgating incidental take regulations
that are overly broad in their scope (‘‘It
is the intention of the Committee that
[ . . . ] the specified activity
[ . . . ] be narrowly identified so that
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the anticipated effects will be
substantially similar.’’). Similarly, the
discussion from NMFS’s and the U.S.
Fish and Wildlife Service’s 1989
implementing regulations (again, before
the 1994 enactment of section
101(a)(5)(D)) was in reference to section
101(a)(5)(A), the provision for incidental
take regulations. There the focus was on
ensuring that the negligible impact
evaluation for an incidental take
regulation under section 101(a)(5)(A)—
not incidental harassment
authorizations under section
101(a)(5)(D)—included the effects of the
total taking by all the entities
anticipated to be conducting the activity
covered by the incidental take
regulation.
We do not mean to suggest that the
legislative history for section
101(a)(5)(A) and our implementing
regulations that preceded enactment of
section 101(a)(5)(D) have no application
to that section. We recognize there is
considerable overlap between the two
provisions. However, there are enough
differences that the two provisions
should not be casually conflated with
one another.
Comment: The Associations state that
they concur with NMFS’s preliminary
determinations of negligible impact on
the affected species or stocks. However,
their comments go on to claim that the
‘‘magnitude’’ and ‘‘impact’’ ratings that
inform our negligible impact
determinations as part of our negligible
impact analysis framework are overly
conservative, and that they disagree
with these aspects of our negligible
impact analyses.
Response: We appreciate the
Associations’ concurrence with our
overall determinations. However, we
disagree with the statements regarding
aspects of our negligible impact
analyses, and feel that these statements
to some degree reflect a
misunderstanding of the framework
elements. In support of their assertion,
the Associations claim that ‘‘high’’ and
‘‘moderate’’ magnitude ratings ‘‘have
never been observed in the multi-decade
history of offshore seismic exploration
[ . . . . ]’’ Magnitude ratings reflect only
the amount of take that is estimated, as
well as the spatial and temporal scale
over which the take is expected to occur
in relation to what is known regarding
a stock’s range and seasonal movements;
therefore, it is incorrect to reference
what has or has not ‘‘been observed’’ in
disputing the validity of the given
magnitude ratings. The Associations
also claim that no survey has had more
than an ‘‘insignificant’’ impact on a
marine mammal species or stock,
without explaining the meaning that
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they assign to this term in context of
their comments or providing any
evidence (as we have stated, lack of
evidence of ‘‘significance’’ does not
constitute evidence of ‘‘insignificance’’).
As this term bears no relevance to the
MMPA’s ‘‘negligible impact,’’ we cannot
comment on the claim. With regard to
the Associations’ comment that our
assigned impact ratings are too high, we
again disagree (noting that these ratings
are developed using the formula
described for our negligible impact
framework); however, absent any
constructive recommendations relating
to the development of the impact ratings
or our framework overall, we cannot
respond further.
Comment: The MMC recommends
that NMFS evaluate the numbers of
Level A harassment takes, in concert
with the Level B harassment takes,
using the negligible impact analysis
framework.
Response: This comment appears
based on a mistaken assumption that we
‘‘assessed only the proposed Level B
harassment takes’’ in our negligible
impact analyses. It is correct that we did
not define quantitative metrics relating
to amount of potential take by Level A
harassment. However, as we state in the
section entitled ‘‘Negligible Impact
Analyses and Determinations,’’ the
authorized taking by Level A
harassment is so low as to not warrant
such detailed analysis. We addressed
the likely impacts of the minimal
amount of takes expected by Level A
harassment, stating that the expected
mild PTS would not likely meaningfully
impact the affected high-frequency
cetaceans, and may have minor effects
on the ability of affected low-frequency
cetaceans to hear conspecific calls and/
or other environmental cues. For all
applicants, the expected effects of Level
A harassment on all stocks to which
such take may occur is appropriately
considered de minimis.
Comment: NRDC claims that NMFS
underestimates the ‘‘magnitude’’
component of the negligible impact
analyses.
Response: NRDC suggests that the
negligible impact framework used in our
Notice of Proposed IHAs positions a ‘‘de
minimis’’ amount of take as
determinative of an ultimate ‘‘de
minimis’’ impact rating. Although not
stated explicitly by NRDC, we agree that
this was inappropriate and have revised
this aspect of our negligible impact
framework. In effect, the proposed
approach meant that a de minimis
amount of take, which would
necessarily lead to a de minimis
magnitude rating, rendered
considerations of likely consequences
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for affected individuals irrelevant. For
example, mysticete whales with a de
minimis amount of take were
automatically assigned an overall de
minimis impact rating, as consequences
were considered not applicable in cases
where a de minimis magnitude rating
was assigned. However, the assessed
level of potential consequences for
individual baleen whales of
‘‘medium’’—which is related to inherent
vulnerabilities of the taxon and other
existing population stressors, and is
therefore not dependent on the specific
magnitude rating—would still exist,
regardless of the amount of take. Under
our revised approach, a mysticete whale
with a de minimis amount of take is
assigned a low impact rating, in light of
the medium consequences rating. These
changes are described further in the
section entitled ‘‘Negligible Impact
Analyses and Determinations.’’
NRDC asserts that impacts resulting
from each of the five separate specified
activities on the endangered North
Atlantic right whale would be greater
than negligible, stating that it is
‘‘inconceivable’’ that impacts should be
considered anything less than ‘‘high,’’
regardless of the expected avoidance of
right whales in time and space. We have
addressed concerns regarding North
Atlantic right whales in greater detail
elsewhere in these comment responses.
While we acknowledge that there will
be some effects to individual right
whales, as it is not possible to conduct
these activities without the potential for
impacts to whales that venture outside
of areas where they are expected to
occur or that undertake migration at
atypical times, impacts to the
population are in fact effectively
minimized for each of these specified
activities. As described later in this
document, we have revised our
exposure analysis for right whales using
the latest and best available scientific
information, and have appropriately
revised our prescribed mitigation on the
basis of that information, as well as
public comment, in such a way as to
reasonably avoid almost all potential
right whale occurrence. We also include
real-time mitigation that would
minimize the effect of any disturbance
on a right whale, in the unexpected
event that an individual was
encountered in the vicinity of a survey.
Accordingly, the impact ratings for
mysticetes are at least ‘‘low’’ versus ‘‘de
minimis’’ (as stated above, we agree that
the impact rating should likely be
greater than de minimis given the
inherent vulnerabilities of the species).
NRDC goes on to state that NMFS uses
a ‘‘non-conservative’’ metric in
characterizing the amount of take, and
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suggests that we should adopt Wood et
al. (2012)’s more conservative approach
for ESA-listed species. NRDC does not
explain how this recommendation will
better satisfy the statutory requirements
of the MMPA. As stated by Wood et al.
(2012), development of metrics for
assessment of the magnitude of effect is
considered particularly subjective.
Rather than invent new metrics in the
absence of any specific rationale or
guidance, we retain use of those given
by Wood et al., which are produced
through expert judgment. We disagree
that the more conservative approach
applied by Wood et al. (2012) for ESAlisted species is appropriate. We believe
that the assessment of amount of take is
a generic consideration, i.e., that the
metrics used to assess this factor are
appropriately applied similarly to all
species. Contextual factors, such as the
status of the species, are applied
elsewhere in the analysis, e.g., through
consideration of likely consequences to
individuals or as a second-order
function of the mitigation that is
developed in reflection of specific
concerns about a given species. NRDC’s
implication that we did not take account
of vulnerable populations in our
negligible impact framework is
incorrect.
Comment: NRDC asserts that the
evaluation of likely consequences to
individuals from species other than
mysticete whales in our negligible
impact analyses is ‘‘problematic.’’
Response: Overall, NRDC basically
provides a blanket suggestion that for all
species impacts should be considered to
be higher than we have determined after
careful consideration of the available
science. NRDC also repeatedly claims
that we have provided no rational basis
for our findings. While we acknowledge
that we bear the responsibility to
support our statutory findings, we
believe we have satisfied that
requirement and, further, NRDC does
not provide adequate justification or
evidence to support their claims.
For sperm whales, NRDC demands
that the likely consequences to
individuals be considered ‘‘high’’ rather
than ‘‘medium,’’ as we have done (on
the basis of presumed heightened
potential for disruption of foraging
activity). In so doing, NRDC primarily
relies upon Miller et al. (2009), as has
NMFS in assuming some heightened
potential for foraging disruption.
However, the evidence provided by the
available literature is not nearly as clear
as NRDC’s comment implies. We agree
that the work of Miller et al. (2009)
indicates that sperm whales in the Gulf
of Mexico are susceptible to disruption
of foraging behavior upon exposure to
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relatively moderate sound levels at
distances greater than the required
general exclusion zone. However, NRDC
misstates the results of the study in
claiming that a nearly 20 percent loss in
foraging success was documented.
Rather, the authors report that buzz
rates (a proxy for attempts to capture
prey) were approximately 20 percent
lower, meaning that the appropriate
interpretation would be that foraging
activity (versus foraging success) was
reduced by 20 percent (Jochens et al.,
2008). This is an important distinction,
as the former implies a cessation of
activity—which may include increased
resting bouts at the surface—during the
relatively brief period that the surveys
transit through the whale’s foraging
area, whereas the latter implies that the
whale is continuing to expend energy in
the hunt for food, without reward.
Moreover, while we do believe that
these results support our contention that
exposure to survey noise can impact
foraging activity, other commenters
have interpreted them differently, e.g.,
by focusing on the finding that exposed
whales did not change behavioral state
during exposure or show horizontal
avoidance (a finding replicated in other
studies, e.g., Madsen et al., 2002;
Winsor et al., 2017), or that the finding
of reduced buzz rates was not a
statistically significant result. In
referencing Bowles et al. (1994), NRDC
fails to state that the observed cessation
of vocalization was likely in response to
a low-frequency tone (dissimilar to
airgun signals), though a distant airgun
survey was noted as producing signals
that were detectable above existing
background noise. However, most
importantly, we expect that the context
of these transitory 2D surveys—as
compared with 3D surveys that may
occur for a longer duration in a given
location, or with repeated survey
activity as may occur in an area such as
the Gulf of Mexico—means that the
potential impacts of the possible
reduction in foraging activity (i.e., likely
consequences on individuals) is limited.
More recently, Farmer et al. (2018)
developed a stochastic life-stage
structured bioenergetic model to
evaluate the consequences of reduced
foraging efficiency in sperm whales,
finding that the ultimate effects on
reproductive success and individual
fitness are largely dependent on the
duration and frequency of disturbance—
which are expected to be limited in
relation to these specified activities.
Thus, we believe our conclusion of
‘‘medium’’ likely consequences is
appropriate.
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With regard to Kogia spp., NRDC
again suggests that NMFS must increase
the level of assumed severity for likely
consequences to individuals. While we
agree that the literature with regard to
kogiid life history is sparse, what
literature is available (as cited in our
Notice of Proposed IHAs) indicates that
these species should be considered as
having a reasonable compensatory
ability when provoked to temporary
avoidance of areas in the vicinity of
active surveys. None of NRDC’s
statements on this topic support their
contention that these consequences
should be considered as more severe,
i.e., the notion that there is little
information available regarding stock
structure is not related to the likely
consequences to individuals of
disturbance. NRDC assumes that such
temporary avoidance necessarily results
in ‘‘displacement from optimal to
suboptimal habitat’’ without any
support. Moreover, it appears that
NRDC misapprehends the conceptual
underpinnings of our negligible impact
analytical framework. The expected
degree of disturbance (‘‘take’’) is
determined in the ‘‘Estimated Take’’
section, and then is coupled with an
understanding of the spatial and
temporal scale of such disturbance
relative to the stock range. Only then is
this comprehensive magnitude rating
combined with the expectation of the
likely consequences of the given
magnitude of effect to yield an overall
impact rating that is then considered
with other relevant contextual factors,
such as mitigation and stock status, in
informing the negligible impact
determination (Figure 5). By seemingly
conditioning its premise on the
acoustically sensitive nature of kogiids,
which is incorporated into the take
estimates and accounted for in the
mitigation requirements, NRDC would
have us overly weight this aspect of
their life history. Our assigned
consequences for Kogia spp. is
appropriate and based on the limited
available literature.
Similarly, for delphinids (for which
NRDC also urges a more severe
assumption of likely consequence to
individuals of the given disturbance),
NRDC states that the consequences must
be considered higher when the
magnitude is high. Again, this is a
misapprehension of the framework: The
assigned ‘‘consequences’’ factor is
independent of the magnitude rating,
and is designed to account for aspects
of a species life history that may make
individuals from that species more or
less susceptible to a biologically
significant degree of impact from a
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given level of disturbance. NRDC’s
additional statements regarding
delphinids appear to again cherry-pick
available literature in support of its
preferred position, e.g., NRDC cites
reactions of dolphins to Navy training
involving explosive detonations (a
dissimilar activity) and suggests that
spotted dolphins are susceptible to
greater disturbance on the basis of Weir
(2008), claiming that this paper
indicates ‘‘pronounced response of
spotted dolphins to operating airguns’’
and supposedly heightened sensitivity.
We do agree that the available
observational data (e.g., Barkaszi et al.,
2012; Stone, 2015a) show that, in
contrast to common anecdotal
statements suggesting that dolphins do
not react at all to airgun noise, dolphins
overall show increased distances to the
noise source or even avoidance when
airguns are operating. However, as
stated elsewhere, these reactions may
not even be appropriately considered as
take (e.g., Ellison et al., 2012), much less
take to which some meaningful
biological significance should be
assigned. In fact, Weir (2008) concludes
that, while spotted dolphin encounters
occurred at a significantly greater
distance from the airgun array when the
guns were firing, there was no evidence
of displacement from the study area,
indicating that even for this supposedly
more sensitive species, greater likely
consequences would not be expected.
As indicated by Weir (2008), these
responses may be short-term and also
occur over relatively short ranges from
the source.
NRDC concludes its criticism of this
aspect of our negligible impact analyses
by demanding that we weight this
assessment of likely consequences to
individuals more highly in the
determination of the overall impact
rating. However, this appears to again
evidence a misapprehension of our
framework and its function. We
certainly agree that an activity that is
found to take small numbers of marine
mammals may not be found to satisfy
the negligible impact standard.
However, here, as in their criticism of
NMFS’s approach to the small numbers
analysis, NRDC inappropriately
conflates the two findings. Here, NRDC
seems to confuse a low magnitude of
effect with the independent small
numbers finding, rather than
understand this magnitude factor as an
important input to the development of
the impact rating. As described in
greater detail in our section entitled
‘‘Negligible Impact Analyses and
Determinations,’’ the impact rating
represents the coupling of the
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magnitude rating and the likely
consequences to individuals in order to
represent the potential impact to the
stock (before considering other
contextual factors). Therefore, although
the likely consequences to individuals
of incidental take may be high, if the
magnitude of effect is low, then the
impact to the stock will not likely be
high. NRDC’s example indicates that it
prefers that the likely consequences to
individuals be determinative of the
impact rating, i.e., they state that it is
inappropriate for a low magnitude
rating and high consequences rating to
couple to produce a moderate impact
rating. Our development of these rating
matrices (Tables 8 and 9) are based on
expert review (Wood et al., 2012) and
appropriately account for the factors
illustrated in Figure 5.
Comment: NRDC claims that the
negligible impact analyses are
inappropriately reliant upon the
prescribed mitigation and, further, that
the mitigation will be ineffective.
Response: First, NMFS did not rely
solely on the mitigation in order to
reach its findings under the negligible
impact standard. As is stated in our
specific analyses, consideration of the
implementation of prescribed mitigation
is one factor in the analyses, but is not
determinative in any case. In certain
circumstances, mitigation is more
important in reaching the negligible
impact determination, e.g., when
mitigation helps to alleviate the likely
significance of taking by avoiding or
reducing impacts in important areas.
Second, while NRDC dismisses the
importance of our prescribed mitigation
by stating that it is ‘‘unsupported by
evidence,’’ NRDC offers no support for
their conclusions.
For example, with regard to the North
Atlantic right whale, consideration of
the mitigation in our negligible impact
analyses was appropriate. That is, it was
appropriate to weigh heavily in our
analyses mitigation that would avoid
most exposures of right whales to noise
at levels that would result in take. We
acknowledge that our proposed
mitigation for right whales was not
sufficient. As described in greater detail
in previous comment responses, as well
as in the section entitled ‘‘Mitigation,’’
we re-evaluated our proposed mitigation
in light of the public comments we
received and on the basis of the best
available information.
NRDC elsewhere stresses the
importance of developing appropriate
habitat-based mitigation—that is,
avoiding impacts in areas of importance
for marine mammals—and not relying
solely on ‘‘real-time’’ mitigation (e.g.,
shutdowns) that allows impacts in those
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areas but minimizes the duration and
intensity of those impacts. Yet despite
our development of time-area measures
for those species where the available
information supports it, NRDC
discounts the benefit of avoiding
disturbance of sensitive and/or deepdiving species in areas where they are
expected to be resident in greatest
numbers. Claims that our prescribed
time-area restrictions are ineffective and
‘‘unsubstantiated’’—and therefore
apparently should not be considered in
our negligible impact analyses—are
contradicted by NRDC’s statements that
habitat-based mitigation are necessary
(‘‘Time and place restrictions designed
to protect important habitat can be one
of the most effective available means to
reduce the potential impacts of noise
and disturbance on marine mammals.’’
(Citing p. 61 of NRDC’s letter)).
However, our revised time-area
restriction for right whales (or
requirement that comparable protection
is achieved through implementation of
a NMFS-approved mitigation and
monitoring plan at distances between
47–80 km offshore) may have alleviated
some of the concerns expressed in the
comment.
NRDC also misunderstands the degree
to which we rely on shutdowns for
sensitive or vulnerable species,
including right whales and beaked
whales, at extended distances. We agree
that these measures in and of
themselves are not likely to carry
substantial benefit, especially for cryptic
species such as beaked whales that are
unlikely to be observed. The prescribed
habitat-based mitigation, i.e., time-area
restrictions, is obviously more
important in minimizing impacts to
these species. However, having
determined practicability, we also
believe that it makes sense to minimize
the duration and intensity of
disturbance for these species when they
are observed, and so include them in the
suite of prescribed measures and
discuss them where appropriate.
Despite their dismissal of these
requirements, we presume NRDC agrees
that the duration and intensity of
disturbance of sensitive species should
be minimized where practicable.
In summary, we have prescribed
practicable mitigation that largely
eliminates takes of North Atlantic right
whales, as indicated by the best
available science and further minimizes
impacts by mitigating for duration and
intensity of exposures. Separately, we
have developed mitigation that protects
use of some of the most important
habitat in the region for other sensitive
species. We consider these measures
appropriately as mitigating factors in the
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context part of our negligible impact
analyses.
Comment: Oceana asserts that our
findings of negligible impact are
improper. In so doing, they make points
that are substantively responded to
elsewhere in these comment responses.
In addition, they also make repeated
reference to the PBR value, claiming
that where harassment takes exceed the
PBR value for a stock, NMFS must deny
the IHA request for failure to meet the
negligible impact standard.
Response: We reiterate that the PBR
metric concerns levels of allowable
removals from a population, and is not
directly related to an assessment of
negligible impact for these specified
activities, which do not involve any
expected potential for serious injury or
mortality. As noted previously, PBR is
not an appropriate metric with which to
evaluate Level B harassment and NMFS
has described and used an analytical
framework that is appropriate. We
appropriately do consider levels of
ongoing anthropogenic mortality from
other sources, such as commercial
fisheries, in relation to calculated PBR
values as an important contextual factor
in our negligible impact analysis
framework, but a direct comparison of
takes by harassment to the PBR value is
not germane. While it is conceptually
possible to link disturbance to potential
fitness impacts to individuals over time
(e.g., population consequences of
disturbance), we have no evidence that
is the case here.
Small Numbers
Comment: The MMC and multiple
commenters recommend that NMFS
provide additional explanation to
support its selection of the 30-percent
limit on marine mammal taking as
meeting the small numbers
determination for the proposed
authorizations. NRDC states that the
interpretation of ‘‘small numbers’’
presented by NMFS in our Notice of
Proposed IHAs is contrary to the plain
meaning and purpose of the MMPA, in
part because NMFS did not provide a
reasoned basis for the take limit
proposed (i.e., 30 percent) (MMC and
others similarly recommended that
NMFS provide additional explanation to
support its selection of the 30-percent
limit on marine mammal taking as
meeting the small numbers
determination for the proposed
authorizations). NRDC makes four
specific claims. First, NRDC states that
30 percent cannot be considered a
‘‘small number.’’ Second, NRDC states
that Congress intended that takes be
limited to ‘‘infrequent, unavoidable’’
occurrences, and that NMFS has not
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explained why the taking would
infrequent or unavoidable. Third, NRDC
contends that NMFS should define
different small numbers thresholds on
the basis of conservation status of
individual species. Finally, NRDC
believes that NMFS must account for
‘‘additive and adverse synergistic
effects’’ that may occur due to multiple
concurrent surveys in conducting a
small numbers analysis.
Response: NMFS agrees that the
Notice of Proposed IHAs did not
provide adequate reasoning for the 30
percent limit. Please see the ‘‘Small
Numbers Analyses’’ section of this
Notice. However, we disagree with
NRDC’s arguments on this topic.
Although NMFS has struggled to
interpret the term ‘‘small numbers’’
given the limited legislative history and
the lack of a biological underpinning for
the concept, we have clarified and better
described our approach to small
numbers. As discussed in the section
entitled ‘‘Small Numbers Analyses,’’ we
describe that the concept of ‘‘small
numbers’’ necessarily implies that there
would also be quantities of individuals
taken that would correspond with
‘‘medium’’ and ‘‘large’’ numbers. As
such, we have established that one-third
of the most appropriate population
abundance number—as compared with
the assumed number of individuals
taken—is an appropriate limit with
regard to ‘‘small numbers.’’ This relative
approach is consistent with Congress’s
statement that ‘‘[small numbers] is not
capable of being expressed in absolute
numerical limits’’ (H.R. Rep. No. 97–
228).
NRDC claims that a number may be
considered small only if it is ‘‘little or
close to zero’’ or ‘‘limited in degree.’’
While we do not accept that a dictionary
definition of the word ‘‘small’’ is an
acceptable guide for establishment of a
reasoned small numbers limit, we also
note that NRDC cherry-picks the
accepted definitions in support of its
favored position. The word ‘‘small’’ is
also defined by Merriam-Webster
Dictionary as ‘‘having comparatively
little size,’’ which comports with the
small numbers interpretation developed
by NMFS and offered here. See
www.merriam-webster.com/dictionary/
small. NRDC cherry-picks the relevant
language by claiming that Congress
intended that the agency limit takes to
those that are ‘‘infrequent, unavoidable’’
occurrences. The actual Congressional
statement is that taking of marine
mammals should be ‘‘infrequent,
unavoidable, or accidental.’’ This
language implies that allowable taking
may in fact be frequent if it is
unavoidable or accidental, both of
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which are the case, even though, in the
case of a large-scale, sound-producing
activity in areas where marine mammals
are present, the takes are not
‘‘infrequent.’’
The argument to establish a small
numbers threshold on the basis of stockspecific context is unnecessarily
duplicative of the required negligible
impact finding, in which relevant
biological and contextual factors are
considered in conjunction with the
amount of take.
Similarly, NRDC’s assertion that take
from multiple specified activities
should be considered in additive
fashion when making a small numbers
finding is not required by section
101(a)(5)(D) of the MMPA. We are
unclear whether the logic presented in
this comment suggests only that a single
small numbers analysis should be
undertaken for the five separate
specified activities considered herein, or
whether NRDC believes that all ‘‘taking’’
to which a given stock may be subject
from all ongoing anthropogenic
activities should be considered in
making a small numbers finding for a
given specified activity. Regardless,
these suggestions from NRDC are not
founded in any relevant requirement of
statute or regulation, discussed in
relevant legislative history, or supported
by relevant case law.
Comment: The MMC recommends
that, in developing generally applicable
guidance for using a proportional
standard to make small numbers
determinations, NMFS either use a
sliding scale that accounts for the
abundance of the species or stock or
explain why it believes that a single
standard should be applied in all cases.
The MMC offers two examples, on
either end of a spectrum, in illustrating
its point. First, MMC provides the
example of a small population of marine
mammals, stating that ‘‘taking the entire
population may arguably constitute a
small number.’’ Second, the MMC
provides the example of a large
population of marine mammals, stating
that ‘‘certain types of taking from large
populations . . . push the limit of what
reasonably may be considered a small
number.’’
Response: NMFS disagrees that such
a ‘‘sliding scale’’ is necessary or
appropriate. Under the ‘‘one-third’’
interpretation offered here, and on
which we base our small numbers
analyses, take equating to greater than
one-third of the assumed individuals in
the population would not be considered
small numbers, other than in certain
extenuating circumstances, such as the
brief exposure of a single group of
marine mammals (as is authorized
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herein for each applicant for such
species as the killer whale). In both of
the MMC’s examples, the MMC
evidently reverts to an absolute
magnitude of the number on the ends of
the spectrum, without regard for the
amount of individuals taken relative to
the size of the population. Historically,
such an approach may have served as a
meaningful limit on actual removals
from a population, prior to the
development of the PBR metric, but is
not a useful consideration when
evaluating takes by Level B harassment
from sound exposure. There is no
meaningful way to define what should
be considered as a ‘‘small’’ number on
the basis of absolute magnitude, and the
MMC offers no such interpretation or
justification.
Comment: The Associations provide a
discussion of several topics relating to
‘‘small numbers’’ and recommend that
NMFS’s small numbers findings be
thoroughly explained in the record for
these actions.
Response: We agree that the basis for
each finding should be explained.
Please see our revised explanation in
‘‘Small Numbers Analyses.’’
Comment: Oceana claims that NMFS
is in violation of the MMPA’s ‘‘small
numbers’’ requirement for a variety of
reasons, including that we authorize
takes of the ‘‘critically endangered’’
North Atlantic right whale and because
we authorize takes of species for which
there are no available abundance
estimates, and relates the potential
biological removal metric to the small
numbers finding. Oceana and many
other commenters also make reference
to a supposed ‘‘Federal court defined’’
take limit of 12 percent of the
appropriate stock abundance.
Response: The reference to a ‘‘Federal
court defined’’ take limit of 12 percent
for small numbers likely comes from a
2003 district court opinion (Natural
Resources Defense Council v. Evans,
279 F.Supp.2d 1129 (N.D. Cal. 2003)).
However, given the particular
administrative record and
circumstances in that case, including
the fact that our small numbers finding
for the challenged incidental take rule
was based on an invalid regulatory
definition of small numbers, we view
the district court’s opinion regarding 12
percent as dicta. Moreover, since that
time the Ninth Circuit Court of Appeals
has upheld a small numbers finding that
was not based on a quantitative
calculation. Center for Biological
Diversity v. Salazar, 695 F.3d 893 (9th
Cir. 1012). Second, while we agree that
there are stocks for which no abundance
estimate is presented in NMFS’s SARs,
there are other available abundance
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estimates for all impacted stocks.
However, more importantly, there is no
requirement in the MMPA to authorize
take only for stocks with available
abundance estimates, or even that a
small numbers finding must necessarily
be based on a quantitative comparison
to stock abundance. We are required
only to use the best available scientific
information in making a small numbers
finding; this information may be
quantitative or qualitative, and may
relate to relevant stock information
other than its overall abundance.
Finally, the PBR metric defines a level
of removals from a population (i.e.,
mortality) that would allow that
population to remain at its optimum
sustainable population level or, if
depleted, would not increase the
population’s time to recovery by more
than 10 percent. We reiterate that it is
inappropriate to make comparisons
between takes by harassment and the
PBR value for any stock.
Comment: The MMC recommends
that NMFS include both the numbers of
Level A and B harassment takes in its
analysis of small numbers.
Response: We agree that this is
appropriate and have done so. Please
see ‘‘Small Numbers Analyses,’’ later in
this document, for full detail.
Comment: TGS states that NMFS
should better explain what it views as
the most appropriate abundance
estimate for each stock.
Response: Please see our revised
discussion of this topic in the section
entitled, ‘‘Description of Marine
Mammals in the Area of the Specified
Activities.’’
Comment: Several commenters
described problems with NMFS’s
proposed approach to ensuring that
actual take estimates remained below
the small numbers threshold proposed
in our Notice of Proposed IHAs, i.e., a
requirement for monthly interim
reporting and a proposed process by
which companies would correct
observations of marine mammals to
obtain an estimate of total takes.
Response: We agree with many of the
points raised by commenters. However,
we discuss only the fundamental
underlying issue here, i.e., our proposed
small numbers analyses, which did not
fully utilize all the information that was
available to refine the number of
individuals taken and prompted
development of a proposed reporting
scheme that was roundly criticized. The
small numbers analyses, described in
our Notice of Proposed IHAs, resulted in
erroneous assessments that enumerated
take estimates for some applicants and
some species would exceed the
proposed small numbers threshold. In
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order to ensure that the proposed
threshold would not be exceeded, we
proposed that applicants would submit
monthly interim reports, including
estimates of actual numbers of takes
(proposed to be produced via correction
of numbers of observed animals for
certain biases using factors described in
Carr et al. (2011)), such that an
authorization could be revoked if actual
take exceeded the proposed small
numbers threshold. While we believe it
is appropriate to correct such
observations in order to best understand
the actual number of takes (discussed
elsewhere in these comment responses),
we agree that this proposal was
inappropriate, i.e., that NMFS should
not issue an incidental take
authorization for an activity for which a
small numbers threshold is expected to
be exceeded. Additionally, such an
approach results in a clearly
impracticable situation for applicants,
who commit substantial expenditure
towards conducting a given survey plan,
but who then may be allowed to
complete only a portion of the plan.
In summary, as a result of our review
of public comments, we re-evaluated the
relevant available information and
produced revised small numbers
analyses (see ‘‘Small Numbers
Analyses,’’ later in this document). The
revised small numbers analyses
alleviated the need for the proposed
take reporting scheme and cap, which
were also challenged by multiple
applicant and public commenters.
Mitigation, Monitoring, and Reporting
Comment: NRDC states that yearround closure is required in the area off
Cape Hatteras. This recommendation
was also made by a group of scientists
from the University of North CarolinaWilmington (D.A. Pabst, W.A. McLellan,
and A.C. Johnson; hereafter, ‘‘Pabst et
al.’’).
Response: In this case, NRDC presents
substantial evidence of the year-round
importance of this habitat to marine
mammals (evidence cited by NMFS in
proposing the area as a seasonal
closure); we agree that this habitat is of
year-round importance. We did not base
the development of this area as a
seasonal restriction because of some
assumption that the area is only
important for a portion of the year
(though the specific seasonal timing is
based on increased density of sperm
whales; see ‘‘Mitigation’’). Rather, our
development of this area as a seasonal
restriction was in consideration of
practicability under the MMPA’s least
practicable adverse impact standard. We
believe NRDC’s comment
inappropriately minimizes the element
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of practicability in a determination of
the measures that satisfy the standard.
In this case, the area is of critical
interest to all applicants—based on the
dated historical survey information from
the region, this area is considered to
potentially be most promising in terms
of hydrocarbon reserves. Therefore, an
absolute proscription on any given
applicant’s ability to collect data in this
area would be impracticable. In such a
case where practicability concerns
would preclude inclusion of an
otherwise valid measure, the measure
must be necessary to a finding of
negligible impact (i.e., the negligible
impact determination cannot be made
and the authorization may not be issued
absent the measure) in order to
supersede the practicability concerns.
While NRDC presents substantial
evidence of the importance of this area
for the marine mammals that use it, they
do not grapple with the practicability
question or justify why the closure must
be year-round for a negligible impact
determination to be made.
We disagree with NRDC’s apparent
contention that surveys conducted in
this region are likely to result in the
death of resident beaked whales. As we
discussed in our Notice of Proposed
IHAs, we recognize the importance of
the concepts described in Forney et al.
(2017), i.e., that for resident animals, it
is possible that displacement may lead
to effects on foraging efficiency that
could impact individual vital rates.
However, no evidence is presented that
severe acute impacts are a reasonably
anticipated outcome for surveys that
will pass through such habitat in a
matter of days.
We also disagree with NRDC’s
summary dismissal of the benefit of
completely restricting survey activity in
the habitat for a portion of the year. The
benefit of a restriction targeting resident
animals is sensibly scaled to the
duration of the restriction and/or the
timing of the restriction in relation to
reproductive behavior. However, we
believe that a full season without acute
noise exposure, at minimum, for those
animals will provide meaningful
benefit, including but not limited to
avoidance of the stress responses of
concern to NRDC elsewhere in their
comments.
Comment: Regarding NMFS’s
proposed time-area restriction in waters
off Cape Hatteras, Pabst et al. state that
recent data from acoustic monitoring
suggest that sperm whales are more
abundant in this area during winter.
Response: NMFS’s initial proposal
was to require implementation of this
restriction from July through September,
in recognition of the limited available
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visual survey data. As noted by
commenters, visual survey data do
suggest that sperm whales are most
common in the Cape Hatteras region in
summer (Roberts et al., 2016). The
commenters go on to note, however, that
more recently available acoustic
monitoring data indicates that the
highest number of sperm whale
detections were made in winter when
visual survey effort was most limited
(Stanistreet et al., 2018). While we
disagree with the commenters’ larger
point, i.e., that the ‘‘Hatteras and North’’
restriction should be in effect yearround (addressed in previous comment
response), we agree with their
interpretation of the data that sperm
whales are more abundant in winter.
Upon review of this newly available
data, we determined it appropriate to
revise the timing of this restriction to
January through March, as described in
‘‘Mitigation.’’
Comment: NRDC, the MMC, and
multiple other commenters state that
NMFS must expand protection of North
Atlantic right whale habitat. Many
commenters referred to the spatial
aspect of the proposed restriction,
though some commenters also referred
to the temporal aspect.
Response: We agree with the
comments referencing the spatial
designation, and we are spatially
expanding the seasonal restrictions
intended to protect right whale
migratory habitat, in addition to
reproductive habitat and for general
protection of right whales (or requiring
that comparable protection is achieved
through implementation of a NMFSapproved mitigation and monitoring
plan at distances between 47–80 km
offshore). Our determination in this
regard and development of this
expanded protection are described in
greater detail elsewhere in these
comment responses, as well as in the
section entitled ‘‘Mitigation.’’ However,
we disagree that the available evidence
supports expansion of this area
temporally. Pabst et al., in
recommending a temporal expansion,
reference an analysis of the composition
and distribution of individual right
whale sightings archived by the North
Atlantic Right Whale Consortium from
1998 through 2015 performed by one of
the comment authors. While this
analysis (as well as more recent acoustic
monitoring data; e.g., Davis et al. (2017))
suggests that right whales are present in
the area in all months of the year, it also
shows that very few occurred outside of
the time window and outside of the
year-round 30-km coastal restriction.
During this period, only five archived
sightings occurred outside of the
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November through April period and
outside of 30 km from shore. Further, it
would be impracticable to completely
close this area to survey activity yearround. As we have acknowledged, it is
possible that whales will be present
beyond this area, or that whales will be
present within this area but at times
outside when migration is expected to
occur. However, we base the time-area
restriction on our best understanding of
where and when most whales will be
expected to occur.
Comment: Several industry
commenters provided comments
regarding NMFS’s proposed exception
to shutdown requirements for certain
species of dolphin. The Associations
stated that, while they appreciate the
exception, it should apply to all dolphin
species, regardless of behavior. They
add that no shutdowns for dolphins are
warranted. CGG also criticized the
proposed behavior-based exception,
instead suggesting that a power-down
requirement be applied as an
alternative. CGG favorably stated that
such a requirement would ‘‘allow for a
tolerable hole in the acquired seismic
data and will not require the vessel to
immediately terminate the survey line
and carry out a six hour circle for infill’’
and that use of power-downs rather than
shutdowns in these circumstances
would result in substantial savings in
operating costs. TGS stated simply that
NMFS ‘‘should consider clarifying and
better addressing bow-riding dolphins’’
and also recommended that NMFS
clarify and better define how to
determine if animals are stationary (in
reference to NMFS’s proposed behaviorbased requirements for dolphins).
Response: Following review of the
available information and public
comments, NMFS agrees that a general
exception to the standard shutdown
requirement is warranted for small
delphinids, without regard to behavior.
We agree with TGS and other
commenters that the intended behaviorbased exception was poorly defined.
However, we do not agree that the
available evidence supports certain
commenters’ assertions that seismic
surveys do not have any adverse effects
on dolphin species. As discussed in
‘‘Mitigation,’’ auditory injury is not
expected for dolphins, but the reason for
dolphin behavior around vessels (when
they are attracted) is not understood and
cannot be assumed to be harmless. In
fact, the analyses of Barkaszi et al.
(2012), Stone (2015a), and Stone et al.
(2017) show that dolphins do avoid
working vessels.
That said, the available information
does not suggest that such reactions are
likely to have meaningful energetic
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effects to individuals such that the
effectiveness of such measures
outweighs the practicability concerns
raised by commenters, in terms of the
operational costs as well as the
difficulty of implementation. All
variations of a conditional shutdown
exception proposed to date (by either
NMFS or BOEM) that include
exceptions based on animal behavior
have been criticized, in part due to the
subjective on-the-spot decision-making
such schemes would require of PSOs.
NMFS finds these criticisms warranted.
If the mitigation requirements are not
sufficiently clear and objective, the
outcome may be differential
implementation across surveys as
informed by individual PSOs’
experience, background, and/or
training. Therefore, the removal of such
measures for small delphinids is
warranted in consideration of the
available information regarding the
effectiveness of such measures in
mitigating impacts to small delphinids
and the practicability of such measures.
As noted above, one commenter
suggested that a power-down
requirement would be practicable
(though we note that this alternative
was offered against the backdrop of
broader claims that no measures should
be required). We considered modifying
the behavior-based shutdown
requirement contained in our proposed
IHAs to CGG’s suggested general power
down requirement. However, following
consultation with applicants and with
BOEM, we determined that the
circumstances of this particular
commenter (CGG) with regard to
practicability may not be broadly
transferable, and that a power down
requirement would potentially lead to
the need for termination of survey lines
and infill of the line where data were
not acquired if a power down was
performed according to accepted
practice, in which the power down
condition would last until the
dolphin(s) are no longer observed
within the exclusion zone. As noted in
our Notice of Proposed IHAs, the need
to revisit missed track line to reacquire
data is likely to result in an overall
increase in the total sound energy input
to the marine environment and an
increase in the total duration over
which the survey is active in a given
area.
We disagree with comments that no
shutdown requirements should apply to
any delphinid species, regardless of
behavior. Here we refer to ‘‘large
delphinids’’ and ‘‘small delphinids’’ as
shorthand for generally deep-diving
versus surface-dwelling/bow-riding
groups, respectively, although the
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important distinction is their dive
behavior rather than their size. As noted
above, industry commenters have
asserted that no shutdown requirements
are warranted for any species of
dolphin, stating that the best available
science does not support imposing such
requirements. The comments
acknowledge that small delphinids are
more likely to approach survey vessels
than large delphinids, but claim without
supporting data that there is no
evidence that large delphinids will
benefit from a shutdown requirement. In
contrast to the typical behaviors of (and
observed effects on) the small delphinid
species group, the typical deep diving
behavior of the relatively rarely
occurring large delphinid group of
species makes these animals potentially
susceptible to interrupted/delayed
feeding dives, which can cause
energetic losses that accrue to affect
fitness. As described in greater detail
elsewhere in this Notice, there are
ample data illustrating the responses of
deeper diving odontocetes (including
large delphinids) to loud sound sources
(including seismic) to include
interrupted foraging dives, as well as
avoidance with increased speed and
stroke rate, both of which may
contribute to energetic costs through
lost feeding opportunities and/or
increased energy demands. Significant
advances in study of the population
consequences of disturbance are
informing our understanding of how
disturbances accrue to effects on
individual fitness (reproduction and
survival) and ultimately to populations
via the use of energetic models, where
data are available for a species, and
expert elicitation when data are still
limited. The link between behavioral
disturbance, reduced energy budgets,
and impacts on reproduction and
survival is clear, as is the value in
reducing the probability or severity of
these behavioral disturbances where
possible. Therefore, we find that there is
support for the effectiveness of the
standard shutdown requirement as
applied to the large delphinid species
group.
Further, the claim of industry
commenters that shutdowns for these
deep-diving species would be
impracticable was not accompanied by
supporting data. The data available to
NMFS demonstrates that this
requirement is practicable. For example,
Barkaszi et al. (2012)’s study of observer
data in the Gulf of Mexico from 2002–
08 (1,440 bi-weekly reports) shows that
large delphinids were sighted on only
1.4% of survey days, and that of these
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sightings, only 58% were within the
500-meter exclusion zone.
Comment: Many commenters
expressed concern regarding the efficacy
of the prescribed visual and acoustic
monitoring methods, stating that species
could go undetected. Some commenters
offer specific recommendations for
changes to staffing requirements.
Finally, some of these commenters state
that NMFS should require operators to
cease work in low-visibility conditions,
because of the difficulty in detecting
marine mammals in such conditions.
Response: While we disagree with
some specific comments regarding
efficacy, we agree with the overall point
that there are limitations on what may
reasonably be expected of either visual
or acoustic monitoring. While visual
and acoustic monitoring effectively
complement each other, and acoustic
monitoring is the most effective
monitoring method during periods of
impaired visibility, there is no
expectation that such methods will
detect all marine mammals present. In
general, commenters appear to
misunderstand what we claim with
regard to what such monitoring may
reasonably be expected to accomplish
and/or the extent to which we rely on
assumptions regarding the efficacy of
such monitoring in reaching the
necessary findings. We appropriately
acknowledge these limitations in
prescribing these monitoring
requirements, while stating why we
believe that visual and acoustic
monitoring, and the related protocols
we have prescribed, are an appropriate
part of the suite of mitigation measures
necessary to satisfy the MMPA’s least
practicable adverse impact standard.
However, our findings of negligible
impact and/or small numbers are in no
way conditioned on any presumption of
monitoring efficacy. With regard to
specific staffing requirements, those
prescribed herein are based on typical
best practices and on review of all
available literature concerning such
practices. Commenters do not offer
compelling information that their
proffered recommendations achieve the
appropriate balance between
enhancement of monitoring
effectiveness and the costs (including
both monetary costs as well as costs in
terms of berth space), and we retain the
requirements originally specified.
Finally, any requirement to cease
operations during low visibility
conditions, including at night, would
not only be plainly impracticable, it
would also likely result in greater
impacts to marine mammals, as such a
measure would require operations to
continue for roughly twice the time.
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Such comments do not align with the
principles we laid out in the ‘‘Proposed
Mitigation’’ section of our Notice of
Proposed IHAs, in which we discussed
the definitively detrimental effects of
increased time on the water and/or
increased or unnecessary emission of
sound energy into the marine
environment, versus the potential and
uncertain negative effect of proceeding
to most efficiently conclude survey
activity by conducting operations even
in low visibility conditions.
Comment: NRDC asserts that NMFS
does not fulfill the MMPA’s requirement
to prescribe mitigation achieving the
‘‘least practicable adverse impact’’ to
marine mammal habitat, and
specifically notes that NMFS does not
separately consider mitigation aimed at
reducing impacts to marine mammal
habitat, as the MMPA requires.
Response: We disagree. Our
discussion of least practicable adverse
impact points out that because habitat
value is informed by marine mammal
presence and use, in some cases there
may be overlap in measures for the
species or stock and for use of habitat.
Here we have identified time-area
restrictions based on a combination of
factors that include higher densities and
observations of specific important
behaviors of the animals themselves, but
also clearly reflect preferred habitat. In
addition to being delineated based on
physical features that drive habitat
function (e.g., bathymetric features,
among others), the high densities and
concentration of certain important
behaviors (e.g., feeding) in these
particular areas clearly indicates the
presence of preferred habitat. Also,
NRDC asserts that NMFS must
‘‘separately’’ consider measures aimed
at marine mammal habitat. The MMPA
does not specify that effects to habitat
must be mitigated in separate measures,
and NMFS has clearly identified
measures that provide significant
reduction of impacts to both ‘‘marine
mammal species and stocks and their
habitat,’’ as required by the statute. Last,
we note that NRDC acknowledges that
NMFS’s measures would reduce
impacts on ‘‘acoustic habitat.’’
Comment: The MMC recommended
that, if NMFS is to require a time-area
restriction to protect spotted dolphins in
shelf waters, the restriction should be
expanded from June through August to
June through September. This
recommendation was made on the basis
of spotted dolphins likely being most
abundant in this area during summer.
Similarly, TGS stated that NMFS should
better support its determination of
seasonality for the proposed restriction.
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Response: Following review of public
comments, NMFS determined that this
proposed time-area restriction was
unlikely to be effective in
accomplishing its intended purpose,
while imposing practicability costs on
applicants. As explained in greater
detail in the ‘‘Mitigation’’ section, we
have eliminated this proposed
requirement. Therefore, the MMC’s
recommendation is no longer relevant.
Comment: NRDC states that NMFS
must require larger buffer zones around
the required time-area restrictions. TGS
stated that NMFS should better support
its choice of 10 km as a buffer distance.
Response: NRDC provides several
reasons why they believe that the
required standard 10-km buffer zones
are insufficient. NRDC claims several
supposed ‘‘erroneous and misplaced
assumptions’’ in the sound field
modeling that informs our standard
buffer zone, which we have refuted
elsewhere in these comment responses.
More substantively, NRDC returns again
to its suggestion that a different
threshold must be used to represent
Level B harassment. We have also
addressed this comment elsewhere.
Here, we reiterate that BOEM’s sound
field modeling, which was conducted in
accordance with the best available
scientific information and methods, and
which remains state-of-the-science,
indicates that the mean distance
(considering 21 different scenarios
combining water depth, season, and
bottom type) to the 160-dB isopleth
would be 6,838 m (range 4,959–9,122
m). Our required 10-km buffer is
appropriate in conservatively
accounting for the potential for sound
exceeding the 160-dB isopleth.
Comment: NRDC stated that in order
to adequately develop habitat-based
protections for marine mammals, NMFS
should, in addition to consideration of
Roberts et al. (2016) and other relevant
information, follow certain guidelines to
protect baleen whale stocks and other
marine mammals: (1) Continental shelf
waters and waters 100 km seaward of
the continental slope; (2) waters within
100 km of all islands and seamounts
that rise within 500 m of the surface;
and (3) high productivity regions not
included under the previous two
guidelines. Although NRDC’s
recommendation is unclear, we assume
that the commenter intends that we
designate such areas as year-round
closures to survey activity.
Response: NMFS relied on the best
available scientific information (e.g.,
Stock Assessment Reports, Roberts et
al., 2016, 2017; numerous study reports
from Navy-funded monitoring and
research in the specific geographic
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region) in assessing density,
distribution, and other information
regarding marine mammal use of
habitats in the study area. In addition,
NMFS consulted LaBrecque et al.
(2015), which provides a specific,
detailed assessment of known
Biologically Important Areas (BIA).
Although BIAs are not a regulatory
designation, the assessment is intended
to provide the best available science to
help inform regulatory and management
decisions about some, though not all,
important cetacean areas. BIAs, which
may be region-, species-, and/or timespecific, include reproductive areas,
feeding areas, migratory corridors, and
areas in which small and resident
populations are concentrated. Because
the BIA assessment may not include all
important cetacean areas, NMFS went
beyond this evaluation in conducting a
core abundance analysis for all species
on the basis of the Roberts et al. (2016)
cetacean density models (described in
detail in our Notice of Proposed IHAs).
NMFS then weighed the results of the
core abundance analysis for each
species in context of the anticipated
effects of each specified activity, other
stressors impacting the species, and
practicability for the applicants in
determining the appropriate suite of
time-area restrictions (see ‘‘Mitigation’’).
Outside of these time-area restrictions,
NMFS is not aware of any evidence of
other habitat areas of particular
importance, or of any compelling
evidence that the planned time-area
restrictions should be modified in any
way when benefits to the species and
practicability for applicants are
considered together.
Regarding NRDC’s recommended
guidelines, we disagree that these would
be appropriate for use in determining
habitats for protection in this
circumstance. The guidelines come from
a white paper (‘‘Identifying Areas of
Biological Importance to Cetaceans in
Data-Poor Regions’’) written by NMFS
scientists for consideration in
identifying such areas in relation to
mitigation development for the
incidental take rule governing the U.S.
Navy’s Surveillance Towed Array
Sensor System Low Frequency Active
(SURTASS LFA) sonar activities, which
was applicable for much of the world’s
oceans, including in many so-called
data-poor areas. NMFS convened a
panel of subject matter experts tasked
with helping to identify areas that met
our criteria for offshore biologically
important areas (OBIAs) for marine
mammals relevant to the Navy’s use of
SURTASS LFA sonar, and the white
paper offered guidance on alternate
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methods for considering data-poor
areas, in view of the fact that data on
cetacean distribution or density do not
exist for many areas of the world’s
oceans. However, such is not the case
for the specific geographic region
considered here. In fact, the white paper
was specifically developed to provide
methods for data-poor areas as an
alternative to use of a global habitat
model (Kaschner et al., 2006) when
such use was determined to result in
both errors of omission (exclusion of
areas of known habitat) and commission
(inclusion of areas that are not known
to be habitat). Here, we do not face the
same lack of data sufficient to inform
the designation of appropriate habitatbased restrictions. As described
previously, we made use of advanced
habitat-based predictive density models,
an existing assessment of BIAs in the
region, and a substantial body of data
from monitoring and research
concerning cetacean distribution and
habitat use in sensitive areas of the
region. Finally, were we to follow
NRDC’s apparent recommendation in
closing all of the areas covered by the
guidelines to survey activity, the
resulting mitigation would not be
practicable for applicants, as a
substantial portion of the planned
survey area would not be available.
Comment: NRDC states that NMFS
should consider time-area closures for
additional species.
Response: We did consider habitatbased protections for species additional
to those discussed in the time-area
restrictions section of ‘‘Mitigation.’’ For
all affected species, we evaluated the
environmental baseline (i.e., other
population-level stressors), the nature
and degree of effects likely to be the
result of the specified activities, and the
information available to support the
development of appropriate time-area
restrictions. We determined that the
available information supported
development of the measures for the
North Atlantic right whale, sperm
whales, beaked whales, and pilot
whales. For other species, context does
not justify additional protections and/or
the available information does not
support the designation of any specific
area for protection. NRDC suggests that
such measures should be developed for
the humpback whale, sei whale, fin
whale, and blue whale. However, NRDC
neither adequately justifies the
recommendation, offering only cursory
reference to the ongoing humpback
whale UME (but not referencing the
otherwise strong health of the West
Indies DPS) and summarily providing
dire conclusions regarding the supposed
effects on all baleen whales,
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notwithstanding that at least two of
these species (the sei whale and blue
whale) are anticipated as being unlikely
to experience any meaningful impacts
from the specified activities. We
addressed NRDC’s recommended use of
a 2010 ‘‘white paper’’ in the previous
comment response; other than this
apparent recommendation that nearly
the entirety of the survey area (e.g.,
continental shelf waters and waters 100
km seaward of the continental slope;
waters within 100 km of all islands and
seamounts that rise within 500 m of the
surface; and high productivity regions
not included under the previous two
guidelines) be declared as a protected
area, NRDC offers no useful
recommendation as to the designation of
protections for these species. Our
development of habitat-based
protections was conducted
appropriately in light of relevant
information regarding the
environmental baseline, expected effects
of the specified activities, and
information regarding species use of the
planned survey area.
Comment: NRDC states that our
development of time-area restrictions
was performed inadequately, and Pabst
et al. also challenged our use of core
abundance areas. TGS stated that we
should better support our use of the 25
percent core abundance area in
determining the time-area restrictions,
and that we should better describe our
consideration of practicability.
Response: NRDC’s primary complaint
is that our use of the ‘‘core abundance
area’’ concept was inadequate, and other
commenters appear to believe that the
core abundance area was the
determining factor in the delineation of
restriction areas. These comments
misapprehend our use of core
abundance areas, as we did not use the
core abundance areas to define habitatbased protections. To clarify, these core
abundance areas did not define the
designated time-area restrictions, but
rather informed and supported our
definition of the appropriate areas.
Further, there is no ‘‘correct’’ answer
regarding the proportion of core
abundance that should inform
development of habitat-based
protections. In part, our analysis of core
abundance areas defined by varying
proportions of the population simply
helped us to adequately visualize areas
within the specific geographic region
that would reasonably be expected to
protect a substantive portion of the
population within a relatively welldefined area. In some cases, this helped
to confirm that stable habitat, i.e.,
habitat defined by bathymetric features
rather than dynamic oceanographic
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characteristics and which would be
expected to provide important habitat to
certain species, is indeed predicted to
host high abundance of these species.
NRDC’s comment regarding the sperm
whale is illustrative. NRDC refers
simply to the 5 percent core abundance
area for sperm whales as ‘‘entirely
inadequate.’’ However, when analyzing
multiple different core abundance areas
for the species, we find that it is
predicted as being broadly distributed
over slope waters throughout much of
the year, i.e., there is little discrete
habitat defined in a way that is suitable
for protection through a restriction on
effort. Therefore, we did not define the
protections on the sole basis of the core
abundance area analysis. Rather, the
core abundance area analysis helped to
highlight that sperm whales should be
expected to be present year-round in
certain deepwater canyons (which also
provide important habitat for beaked
whales); the spatial definition of these
areas does not in fact align with the
predicted core abundance area, but
rather with the bathymetric features that
provide the conditions that lead to the
predictions of high abundance in the
first place, as is appropriate. Separately,
the 5 percent core abundance area
highlighted that, in contrast with the
broad slope area over which sperm
whales are generally expected to occur,
a discrete area off of Cape Hatteras (i.e.,
‘‘The Point’’) would be expected to
provide attractive habitat to sperm
whales throughout the year, thus
enabling us to include this area, with
other areas of importance for the sperm
whale and other species, in the
conglomerate ‘‘Hatteras and North’’
(Area #4).
Our definition of the Hatteras and
North area was primarily informed by
review of the available literature (as
described in our Notice of Proposed
IHAs), which shows that, for example,
beaked whales are consistently present
in particular waters of the shelf break
region at all times of year (e.g., McLellan
et al., 2018; Stanistreet et al., 2017);
relatively high numbers of sperm
whales are present off of Cape Hatteras
year-round (but particularly in the
winter) (Stanistreet et al., 2018); and
pilot whales have a strong affinity for
the shelf break at Cape Hatteras and
waters to the north (e.g., Thorne et al.,
2017). These findings provided a strong
indication that the area should be
afforded some degree of protection in
the form of restriction on effort, while
the core abundance analysis both
supported these findings and provided
a more quantitative basis upon which to
delineate the specific area.
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We also acknowledge the important
role that practicability for applicants
plays in defining the appropriate suite
of mitigation requirements to satisfy the
MMPA’s least practicable adverse
impact standard, including design of
habitat-based protections. Where a
negligible impact finding is not
conditioned upon the implementation
of specific mitigation, prescription of
mitigation must consider impacts on
practicability. As stated above,
protection of additional habitat for the
sperm whale—given no basis on which
to specify targeted protections beyond
those included herein—would
necessarily involve restricting access to
large swaths of the specific geographic
region. Based on our understanding of
applicant considerations, such
significant restrictions would likely lead
to an applicant’s determination that the
survey would not take place, as the
return on investment would not justify
the expenditure, i.e., a clear-cut case of
a fatal practicability issue. In the
absence of necessity (i.e., the measure
must be prescribed in order to make a
finding of negligible impact), it would
not be permissible to require such
stringent restrictions.
NRDC goes on to cite ‘‘important
passive acoustic detections,
opportunistic sightings, and other data’’
that we have supposedly ignored, and
cites the New York Bight (an area
outside the specific geographic region)
as an area illustrating the supposed
failure of the density models to
adequately highlight important habitat.
NRDC also references biologically
important areas; as described later in
this document, we reviewed available
information regarding BIAs (LaBrecque
et al., 2015) and there are no additional
identified BIAs in the region.
In summary, and contrary to NRDC’s
statements, we did not rely exclusively
on the core abundance analysis to
define restriction areas. While we may
have inadvertently overemphasized this
important aspect of our process in the
description provided in our Notice of
Proposed IHAs, we evaluated the
available literature to inform our
understanding of rough areas suitable
for protection (or characteristics that
might provide such areas), subsequently
refining our analysis through use of core
abundance analysis to identify specific
areas where features expected to
provide important habitat overlap with
actual predictions of high abundance
and/or to refine the specific boundaries
of areas that the literature indicated to
be of importance. We appropriately
based our definition of time-area
restrictions on the available literature as
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well as on our analysis of core
abundance areas.
Comment: ION requests that we
reconsider the proposed time-area
restrictions, based on a supposed lack of
effects to right whales from noise
exposure, the lack of evidence for
serious injury, death, or stranding of
beaked whales due to noise exposure
from airgun surveys, and the possibility
that deepwater canyon closures could
be timed to coincide seasonally with the
lowest density of sperm whales.
Response: We refer to the discussions
provided in our Notice of Proposed
IHAs regarding ‘‘Potential Effects of the
Specified Activity on Marine Mammals’’
and detailing the rationale and basis for
our designation of time-area restrictions
in ‘‘Proposed Mitigation.’’ We stand by
this information as supporting our
assumptions regarding likely effects of
marine mammals and the need for such
time-area restrictions, and regarding the
basis upon which we designated
specific restrictions. Specifically, we
have designated the relatively small
deepwater canyon areas as year-round
closures due to the likelihood that they
provide year-round habitat to beaked
whales and possibly sperm whales,
while resulting in relatively minor
practicability impacts. ION claims that
these three deepwater canyon closures
would result in ‘‘large gaps in the
seismic data acquired,’’ but the map
provided as Figure 1 in ION’s letter does
not support this contention, instead
showing that only very small portions of
several planned survey lines pass
through these areas.
Comment: CGG suggests that NMFS
should evaluate observational data
submitted during the course of the
survey and only require time-area
restrictions ‘‘if potential significance of
behavioral disruption and potential for
longer-term avoidance exists as a result
of acoustic exposure’’ from the survey.
Response: We disagree that this
would be the appropriate approach to
implementation of required restrictions.
We also note that CGG mistakenly states
that distribution of some species
targeted in our design of restrictions is
modeled through use of stratified
models, implying that not enough
information exists on which to base
such restrictions. Our restriction areas
target coastal bottlenose dolphins, North
Atlantic right whales, beaked whales,
sperm whales, and pilot whales, none of
which are modeled through stratified
models. More importantly, the entire
premise of time-area restrictions is that,
on the basis of a reasoned consideration
of available information regarding the
anticipated impacts to the affected
species or stocks, their status, use of
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habitat, and practicability for
applicants, restrictions on survey effort
to completely or partially avoid
sensitive habitat are appropriate.
Moreover, it would not be appropriate
to allow the surveys to occur in those
places, thereby potentially allowing the
impacts to sensitive habitat and/or
disruption of critical behaviors at
important places and/or times, and
expect that observational data collected
during the survey would adequately
indicate that the restriction should in
fact be in place.
Comment: The Associations state that
right whale dynamic management areas
(DMA) should not be used as
operational restriction areas, and that
areas designated to identify the presence
of right whales cannot be used for
multiple purposes, e.g., to reduce risk of
ship strike and to avoid harassment.
Response: The DMA concept
recognizes that aggregations of right
whales can occur outside of areas and
times where they predictably and
consistently occur, and it can be applied
in various contexts. The DMA construct
is used to help reduce risk of ship strike
for right whales in association with
NMFS’s regulations for vessel speed
limits in prescribed ‘‘seasonal
management areas’’ (73 FR 60173;
October 10, 2008; extended by 78 FR
73726; December 9, 2013). In that
regard, when a specific aggregation of
right whales is sighted, NMFS ‘‘draws’’
a temporary zone (i.e., DMA) around the
aggregation and alerts mariners. DMAs
are in effect for 15 days when
designated and automatically expire at
the end of the period, but may be
extended if whales are re-sighted in the
same area.
The DMA concept also was used
between 2002 and 2009 to protect
unexpected aggregations of right whales
that met an appropriate trigger by
temporarily restricting lobster trap/pot
and anchored gillnet fishing in the
designated area (gear modifications have
since replaced those requirements).
As we have stated, it is critically
important to avoid impacts to right
whales when possible and to minimize
impacts when they do occur. Because
DMAs identify aggregations of right
whales, it is appropriate to restrict
operations in these areas when DMAs
are in effect. While we acknowledge that
this requirement will impose
operational costs, if the establishment of
a DMA results in the need for a survey
to temporarily move to another location,
such concerns are weighted
appropriately here in determining that
this measure should be included in the
suite of mitigation necessary to achieve
the least practicable adverse impact.
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Comment: ION suggests that NMFS
reconsider its position on use of
mitigation sources and power-downs,
i.e., that NMFS should allow these
approaches to reduce operational
impacts of required mitigation.
Response: We maintain that use of a
‘‘mitigation source’’—commonly
understood to involve firing of a single
airgun for extended periods of time to
avoid the need for pre-clearance and/or
ramp-up—is inappropriate here. Our
position on this is not based on a lack
of evidence that the mitigation source
would be effective—indeed, we agree
that it is reasonable to assume some
degree of efficacy for a mitigation gun in
providing a ‘‘warning’’ to marine
mammals, as we discuss in reference to
use of ramp-up. Our determination is
instead based on a consideration that
unnecessary introduction of sound
energy into the water, as occurs during
use of a mitigation source, is necessarily
a deleterious impact, whereas the
alternative—allowance of start-up at
times of poor visibility—may result in
negative impacts to individual marine
mammals in the vicinity, but this is not
certain.
Comment: Several commenters
criticized our proposal to require
shutdowns upon detection of certain
species or circumstances (e.g., beaked
whales, right whales, whales with
calves) at any distance. The
Associations suggest that such
requirements are ‘‘unreasonable’’
because they require shutdowns ‘‘for
circumstances in which no Level A or
Level B harassment will occur,’’ and
recommend that such measures be
limited to power-down only for
detections within 1,000 m. The
Associations also contend that these
measures will have negative impacts on
the effectiveness of visual PSOs, stating
that the result would be that ‘‘observers
will be constantly monitoring an
unlimited zone, which [ . . . ] may
undermine the effectiveness of their
monitoring of the 1,000 m zone.’’ CGG
makes similar claims, adding that these
measures would result in a substantial
increase in operating costs.
Response: We first note that the
minimum Level B harassment zone for
any survey, in any location, would be
beyond the likely detection distance for
visual observers, even under ideal
conditions, e.g., the smallest threshold
radius out of 21 modeled scenarios from
BOEM’s PEIS was almost 5 km.
Therefore, the Associations’ claim that
shutdowns at any distance would occur
in circumstances where there is no
harassment is incorrect. Overall, we
disagree with these comments, as well
as those specific comments we respond
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to below, which assert that such
measures are not warranted. In these
cases, we have identified species or
circumstances with particular
sensitivities (in conjunction with, in
some cases, a high magnitude of
authorized take) for which we believe it
appropriate to minimize the duration
and intensity of the behavioral
disruption, as well as to minimize the
potential for auditory injury (for lowand high-frequency cetaceans).
However, while we also disagree that
trained, experienced professional PSOs
would somehow misunderstand our
intent and spend undue time focusing
observational effort at distances beyond
approximately 1,000 m from the
acoustic source (i.e., the zone within
which we assume that monitoring is
typically focused, though not
necessarily exclusively), in order to
ensure that this potential is minimized,
and to alleviate to some degree the
operational cost associated with
shutdowns at any distance, we limit
these shutdowns to within 1.5 km
(versus at any distance). The rationale
for this distance is explained later in
this document in ‘‘Mitigation.’’
Comment: Several commenters
criticized the proposal to require
shutdowns based upon aggregations of
six or more marine mammals in a state
of travel, stating that such a measure is
‘‘vague and unbounded’’ and would be
impracticable due to the large number of
shutdowns that may result.
Response: We acknowledge that this
measure, as described in our Notice of
Proposed IHAs, does not likely carry
benefits commensurate with the likely
costs and is therefore impracticable.
However, the provided description was
in error in that it inadvertently
suggested requirements beyond what we
intended, i.e., we did not intend that
this measure would apply to species
that commonly occur in large groups,
such as dolphins. We have modified
this requirement to clearly state that it
applies only to aggregations of large
whales (i.e., baleen whales and sperm
whales), and to eliminate the behavioral
aspect of the requirement, as
recommended by commenters. Contrary
to claims of commenters, this measure
(as clarified/revised) is warranted, in
that minimization of disruption for
aggregations of resting and/or
socializing whales is important and also
practicable. As described above, the
shutdown requirement is bounded by a
maximum distance of 1.5 km.
Comment: Multiple industry
commenters criticized the proposed
requirement for shutdowns upon
observation of a diving sperm whale
centered on the forward track of the
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source vessel, stating that the proposal
was unclear and likely unworkable.
Response: We agree with commenters
(though we disagree with associated,
unsupported statements regarding lack
of effects to sperm whales), and have
removed this measure.
Comment: TGS stated that we should
remove the requirement (specific to
TGS) to shut down upon observation of
any fin whale.
Response: For reasons described in
greater detail in the section entitled
‘‘Mitigation,’’ we agree with this
comment and have removed the
measure.
Comment: The Associations and other
industry commenters state that the
requirement for shutdowns upon
observation of large whales with calf is
not warranted and will be ‘‘very
impracticable because of the large
number of . . . shutdowns it will
generate.’’
Response: We disagree with these
comments and retain this requirement,
albeit within the 1.5 km zone versus ‘‘at
any distance.’’ As we discuss in the
‘‘Mitigation’’ section, groups of whales
are likely to be more susceptible to
disturbance when calves are present
(e.g., Bauer et al., 1993), and
disturbance of cow-calf pairs could
potentially result in separation of
vulnerable calves from adults.
Separation, if it occurred, could be
exacerbated by airgun signals masking
communication between adults and the
separated calf (Videsen et al., 2017).
Absent separation, airgun signals can
disrupt or mask vocalizations essential
to mother-calf interactions. Given the
consequences of potential loss of calves
in context of ongoing UMEs for multiple
mysticete species, as well as the
functional sensitivity of the mysticete
whales to frequencies associated with
airgun survey activity, we believe this
measure is warranted by the MMPA’s
least practicable adverse impact
standard. Commenters provide no
justification for the claim that this
measure will result in a large number of
shutdowns.
Comment: Several industry
commenters also suggest that there is
not adequate justification for enhanced
shutdown requirements for right
whales, beaked whales, or Kogia spp.
These commenters all provide the same
points verbatim (paraphrased here): (1)
Because the primary threat facing right
whales are entanglement with fishing
gear and ship strikes, enhanced
shutdowns have no impact on the
causes of right whale decline; (2) while
acknowledging that beaked whales are
acoustically sensitive, they claim that
evidence does not exist regarding
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sensitivity to airgun noise; and (3) Kogia
spp. are grouped with high-frequency
cetaceans (and thus are subject to
greater propensity for auditory injury)
on the basis of studies of harbor
porpoise; therefore, this classification is
invalid.
Response: These claims lack merit,
and we retain these requirements (albeit
within the 1.5 km zone versus ‘‘at any
distance’’). We agree that the primary
threats to right whales are entanglement
and ship strike, but the deteriorating
status of the population (discussed in
detail in the section entitled
‘‘Description of Marine Mammals in the
Area of the Specified Activities’’)
indicates that impacts to individual
right whales should be avoided where
possible and otherwise minimized. The
preponderance of evidence clearly
demonstrates that beaked whales are
acoustically sensitive species. While
beaked whale stranding events have
been associated with use of tactical
sonar, indicating that this specific noise
source may be more likely to result in
behaviorally-mediated mortality, the
lack of such association with airgun
surveys does not mean that beaked
whales are less acoustically sensitive to
the noise source. The same holds for
Kogia spp., albeit with less evidence for
these cryptic species. However,
commenters’ claim regarding the
classification of these species into the
high-frequency hearing group holds no
merit. The best available scientific
information, while limited, indicates
that these species are appropriately
classed as high-frequency cetaceans;
commenters provide no evidence to the
contrary. While no data exists regarding
Kogia spp. hearing, these species were
appropriately classified as highfrequency cetaceans by Southall et al.
(2007) on the basis of high-frequency
components of their vocalizations. More
recent data confirms that Kogia spp. use
high-frequency clicks (Merkens et al.,
2018) and, by extension, that their
classification as high-frequency
cetaceans is appropriate.
Comment: The MMC recommends
that NMFS require shutdowns upon
acoustic detection of sperm whales, as
is required for beaked whales and Kogia
spp.
Response: We agree with the MMC
that shutdowns due to the presence of
sperm whales should not be limited to
visual detection alone. This
recommendation appears to reflect some
ambiguity in the description of
proposed mitigation provided in our
Notice of Proposed IHAs, as it was our
intent to prescribe mitigation in
accordance with this recommendation.
In conjunction with modifications to the
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proposed mitigation (described in full in
the section entitled ‘‘Mitigation’’), we
require that shutdowns be implemented
upon confirmed acoustic detection of
any species (other than delphinids)
within the relevant exclusion zone.
Comment: NRDC and other
commenters state that NMFS should
prescribe requirements for use of
‘‘noise-quieting’’ technology. NRDC
elaborates that in addition to requiring
noise-quieting technology (or setting a
standard for ‘‘noise output’’), NMFS
should ‘‘prescribe targets to drive
research, development, and adoption of
alternatives to conventional airguns.’’
Response: We agree with commenters
that development and use of quieting
technologies, or technologies that
otherwise reduce the environmental
impact of geophysical surveys, is a
laudable objective and may be
warranted in some cases. However, here
the recommended requirements are
either not practicable or are not within
NMFS’s authority to require. To some
degree, NRDC misunderstands our
discussion of this issue as presented in
our Notice of Proposed IHAs. We
recognize, for example, that certain
technologies, including the Bolt eSource
airgun, are commercially available, and
that certain techniques such as
operation of the array in ‘‘popcorn’’
mode may reduce impacts when viable,
depending on survey design and
objectives. However, a requirement to
use different technology from that
planned or specified by an applicant—
for example, a requirement to use the
Bolt eSource airgun—would necessarily
require an impracticable expenditure to
replace the airguns planned for use.
NRDC offers no explanation for why
such an incredible cost imposition (in
the millions of dollars) should be
considered practicable. Separately,
NRDC appears to suggest that NMFS
must require or otherwise incentivize
the development of wholly new or
currently experimental technologies. In
summary, while we agree that noise
quieting technology is beneficial, the
suggestions put forward by commenters
are either impracticable or outside the
authority provided to NMFS by the
MMPA. However, NMFS would
consider participating in related efforts
by NRDC or any other commenter
interested in these technologies.
Comment: NRDC claims that NMFS
fails to consider mitigation to reduce
ship strike in right whale habitat.
Separately, NRDC states that NMFS
should consider extending ship-speed
requirements to all project vessels
within ‘‘the North Atlantic right whale
BIA.’’
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Response: We disagree with NRDC’s
contention. All project vessels are
required to adhere to vessel speed
requirements. Indeed, the ship speed
restrictions in these IHAs are required of
all vessels associated with the surveys,
regardless of length, whereas NMFS’s
ship speed regulations apply only to
vessels greater than 65 ft in length. We
agree with NRDC that ship speed
requirements are warranted for all
project vessels in designated areas to
minimize risk of strike for right whales.
However, we are unclear what specific
area NRDC may mean in referencing
‘‘the North Atlantic right whale BIA.’’
We require that all project vessels
adhere to a 10-kn speed restriction
when in any seasonal or dynamic
management area, or critical habitat.
Comment: Industry commenters were
unanimous in expressing concern
regarding required vessel strike
avoidance mitigation measures, notably
regarding safety for operators. In
particular, recommendations to reduce
speed and shift engines to neutral in
certain circumstances were viewed as
unsafe for vessels towing gear.
Response: We agree with the concerns
expressed by commenters, and clarify
that it was not our intent to require such
measures for vessels towing gear. Safety
of human life is paramount, and where
legitimate concerns exist we agree that
required mitigation must reflect such
concerns. We have revised our
discussion of vessel strike avoidance
measures (see ‘‘Mitigation’’) to clarify
that the primary requirements are (1) all
vessels must observe a 10-kn speed limit
when transiting right whale critical
habitat, SMAs, or DMAs, and (2) all
vessels must observe separation
distances identified in ‘‘Mitigation,’’ to
the extent practicable as relates to
safety. These requirements do not apply
to the extent that a vessel is restricted
in its ability to maneuver and, because
of the restriction, cannot comply or in
any case where compliance would
create an imminent and serious threat to
a person or vessel. Speed alterations
(aside from the 10-kn restriction, when
applicable), alterations in course, and
shifting engines to neutral are
recommendations for how separation
distances may be achieved but are not
requirements, and do not apply to any
vessel towing gear.
Comment: ION requests clarification
on specific ‘‘precautionary measures’’
required in order to minimize potential
for vessel strike, citing the following
text from our Notice of Proposed IHAs:
‘‘Vessel speeds must also be reduced to
10 kn or less when mother/calf pairs,
pods, or large assemblages of cetaceans
are observed near a vessel. A single
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cetacean at the surface may indicate the
presence of submerged animals in the
vicinity of the vessel; therefore,
precautionary measures should be
exercised when an animal is observed.’’
Response: We clarify here that the
latter statement, i.e., ‘‘precautionary
measures should be exercised when an
animal is observed,’’ carries no specific
requirements. We intend only that
vessel operators act cautiously in
accordance with established practices of
seamanship to avoid striking observed
animals. The requirements of the former
statement, i.e., that vessel speeds must
be reduced when mother/calf pairs,
pods, or large assemblages of cetaceans
are observed near a vessel, applies only
to those specific circumstances, i.e., not
in speculative fashion if a single animal
or small group of animals is observed.
Comment: One individual stated that
NMFS should require applicants to
monitor propagation conditions,
suggesting that this could be
accomplished through use of
conductivity, temperature, and depth
(CTD) measurement devices, and that
vessels should not be allowed to operate
when propagation is ‘‘exceptionally
efficient.’’
Response: The commenter does not
specify what propagation conditions
should be considered ‘‘exceptionally
efficient.’’ Regardless, we do not agree
that such a requirement is warranted.
The sound field modeling conducted by
BOEM and by the applicants that did
not make use of BOEM’s modeling is
purposely designed to reflect a
reasonable range of propagation
conditions that are expected to be
encountered in the region. This does not
mean that there will never be
unexpected conditions that may result
in propagation beyond the modeled
distances. However, this potential does
not require that operators cease
operating, as such a requirement would
be fraught with uncertainty and
potentially result in significant
additional operating costs.
Comment: NRDC makes several
recommendations relating to the use of
ramp-up.
Response: First, NRDC states that
NMFS should require that ramp-up
occur over several stages in order to
minimize exposure. We agree with
NRDC on this point, but are confused by
the recommendation, which appears to
restate the ramp-up procedures
described by NMFS in our Notice of
Proposed IHAs. Second, NRDC states
that we ‘‘should give greater
consideration to the requirements that
apply after shutdown periods.’’ Again,
we are unclear as to what NRDC’s
specific recommendation is, but NRDC
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appears to criticize the allowance of an
array restart without ramp-up, assuming
that constant observation has been
maintained without marine mammal
detection. NRDC does not state what
they believe to be the problem with this
allowance, and we believe that it is
consistent with current practice and
appropriate in context of the ‘‘least
practicable adverse impact.’’ Finally,
NRDC asserts that the half-hour cutoff
‘‘perversely incentivizes’’ continuous
firing to avoid the delay of pre-clearance
and ramp-up. This is another confusing
statement, as we explicitly disallow
airgun firing when not necessary for
data acquisition, e.g., during line turns.
Comment: NRDC complains that the
standard 500-m exclusion zone is
‘‘plainly insufficient to prevent auditory
injury,’’ and many other commenters
echo these comments regarding the
sufficiency of the prescribed exclusion
and buffer zones.
Response: We have acknowledged
that some limited occurrence of
auditory injury is likely, for low- and
high-frequency cetaceans. However, we
disagree that a larger standard exclusion
zone is warranted. As we explained in
our Notice of Proposed IHAs, our intent
in prescribing a standard exclusion zone
distance is to (1) encompass zones for
most species within which auditory
injury could occur on the basis of
instantaneous exposure; (2) provide
additional protection from the potential
for more severe behavioral reactions
(e.g., panic, antipredator response) for
marine mammals at relatively close
range to the acoustic source; (3) provide
consistency and ease of implementation
for PSOs, who need to monitor and
implement the exclusion zone; and (4)
to define a distance within which
detection probabilities are reasonably
high for most species under typical
conditions. Our use of 500 m as the
zone is not based directly on any
quantitative understanding of the range
at which auditory injury would be
entirely precluded or any range
specifically related to disruption of
behavioral patterns. Rather, we believe
it is a reasonable combination of factors.
In summary, a practicable criterion such
as this has the advantage of familiarity
and simplicity while still providing in
most cases a zone larger than relevant
auditory injury zones, given realistic
movement of source and receiver.
Increased shutdowns, without a firm
idea of the outcome the measure seeks
to avoid, simply displace survey activity
in time and increase the total duration
of acoustic influence as well as total
sound energy in the water (a goal we
believe NRDC supports).
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We agree that, when practicable, the
exclusion zone should encompass
distances within which auditory injury
is expected to occur on the basis of
instantaneous exposure. For highfrequency cetaceans, these distances
range from 355–562 m for four of the
five applicants (Table 5). For Spectrum,
the predicted distance is significantly
larger (1,585 m). However, we require
an extended exclusion zone of 1.5 km
for certain sensitive species, including
Kogia spp. This means that only one
rarely occurring species (harbor
porpoise), and for only one applicant, is
left unprotected from potential auditory
injury in terms of the prescribed
distance of the exclusion zone.
Moreover, it is unlikely that harbor
porpoise would even be detected at
distances greater than 500 m. Potential
auditory injury for low-frequency
cetaceans is based on the accumulation
of energy, and is therefore not a
straightforward consideration. For
example, observation of a whale at the
distance calculated as being the ‘‘injury
zone’’ does not necessarily mean that
the animal has in fact incurred auditory
injury. Rather, the animal would have to
be at the calculated distance (or closer)
as the mobile source approaches, passes,
and recedes from the exposed animal,
being exposed to and accumulating
energy from airgun pulses the entire
time, as is implied by the name of the
‘‘safe distance’’ methodology by which
such zone distances are calculated.
Therefore, we disagree that it is sensible
to create a larger exclusion zone on the
basis of the calculated injury zones
(although we note that the extended 1.5
km exclusion zone is required for right
whales). We also note that the
maximum distance cited by NRDC
(4,766 m) was an error in our Notice of
Proposed IHAs (corrected later in this
document; see ‘‘Level A harassment’’ in
the ‘‘Estimated Take’’ section). In fact,
the calculated injury distances for two
applicants are less than the standard
500-m zone, while those calculated for
the remaining three applicants range
from 757–951 m. In keeping with the
four broad goals outlined above, and in
context of the information given here,
our standard 500-m exclusion zone is
appropriate.
Comment: Several industry
commenters criticized the requirement
for use of a buffer zone, in addition to
the standard 500-m exclusion zone,
claiming in part that use of such a buffer
is ‘‘counterintuitive.’’
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Response: Having received multiple
comments indicating confusion
regarding the proposed measure, we
first clarify that the requirement is for a
500-m buffer zone in addition to the
500-m standard exclusion zone, i.e.,
total typical monitoring zone of 1,000
m, and that the implementation of this
requirement relates primarily to the preclearance period, when the full 1,000-m
zone must be clear of marine mammals
prior to beginning ramp-up. During fullpower firing, the buffer zone serves only
as a sort of ‘‘warning’’ area, where the
observation of marine mammals should
incite readiness to shut down, should
those animals enter the 500-m
shutdown zone.
We disagree that this measure is
counterintuitive, an assertion based on
the apparent sense that a larger zone
should be in effect when the array is
firing and a smaller zone prior to firing.
On the contrary, we believe it important
to implement a larger zone during preclearance, when naı¨ve animals may be
present and potentially subject to severe
behavioral reactions if airguns begin
firing at close range. While the
delineation of zones is typically
associated with shutdown, the period
during which use of the acoustic source
is being initiated is critical, and in order
to avoid more severe behavioral
reactions it is important to be cautionary
regarding marine mammal presence in
the vicinity when the source is turned
on. This requirement has broad
acceptance in other required protocols:
The Brazilian Institute of the
Environment and Natural Resources
requires a 1,000-m pre-clearance zone
(IBAMA, 2005), the New Zealand
Department of Conservation requires
that a 1,000-m zone be monitored as
both a pre-clearance and a shutdown
zone for most species (DOC, 2013), and
the Australian Department of the
Environment, Water, Heritage and the
Arts requires an even more protective
scheme, in which a 2,000-m ‘‘power
down’’ zone is maintained for higherpower surveys (DEWHA, 2008). Broker
et al. (2015) describe the use of a
precautionary 2-km exclusion zone in
the absence of sound source verification
(SSV), with a minimum zone radius of
1 km (regardless of SSV results). We
believe that the simple doubling of the
exclusion zone required here is
appropriate for use as a pre-clearance
zone.
Comment: In writing about the
exception made for dolphins from the
shutdown requirements, NRDC states
that ‘‘more analysis is . . . needed of
the potential costs and benefits of
excluding bow-riding dolphins from the
exclusion zone requirement.’’
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Response: We recognize the concerns
raised by NRDC, and agree that the
reasons for bow-riding behavior are
unknown and, further, that in context of
an active airgun array, the behavior
cannot be assumed to be harmless.
However, dolphins have a relatively
high threshold for the onset of auditory
injury and, for small delphinids, more
severe adverse behavioral responses are
less likely given the evidence of
purposeful approach and/or
maintenance of proximity to vessels
with operating airguns. With regard to
the former point, Finneran et al. (2015)
exposed bottlenose dolphins to repeated
pulses from an airgun and measured no
TTS. Therefore, the biological benefits
of shutting down for small delphinids
are expected to be comparatively low,
whereas, as indicated through public
comment on these proposed actions, the
costs of the shutdowns for survey
operators is high. Therefore, our
consideration of this subject, as
addressed in an earlier comment
response, indicates that a general (rather
than behavior-based) small delphinid
exception to the standard shutdown
requirement is an appropriate part of the
suite of mitigation measures necessary
to effect the least practicable adverse
impact.
Comment: One individual stated that
NMFS should require ‘‘trackline design’’
that minimizes the potential for
stranding, including by requiring that
companies run their nearshore lines at
times of reduced propagation efficiency.
Response: The commenter does not
specify what is meant by ‘‘nearshore,’’
but we prescribe a year-round 30-km
standoff from the coast. We assume that
30 km is sufficient to accomplish the
commenter’s objective in making the
recommendation.
Comment: The Associations and other
industry commenters raise several
concerns regarding the PSO
requirements. These are: (1) Concern
regarding NMFS’s requirement to
review PSO qualifications and
associated potential for delay, with
accompanying recommendation that
such reviews be ‘‘bounded by some
reasonably short time period, with the
default being that the observer is
approved if NMFS fails to respond
within that time period’’; (2) concern
whether vessels can ‘‘safely
accommodate’’ the number of PSOs
required by NMFS’s staffing
requirements; and (3) a claim that
NMFS’s requirements for PSOs will
result in labor shortages, and an
accompanying recommendation that
these be ‘‘guidelines’’ rather than
requirements.
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Response: We agree with the first
concern, and have clarified that NMFS
will have one week to review PSO
qualifications (from the time that NMFS
confirms that adequate information has
been submitted) and either approve or
reject a PSO. If NMFS does not respond
within this time, any PSO meeting the
minimum requirements would
automatically be approved.
We disagree with the remainder of the
statement. NMFS has evaluated the
appropriate PSO staffing requirements,
as described in ‘‘Mitigation,’’ and we
have determined that a minimum of two
visual PSOs must be on duty at all times
during daylight hours in order to
adequately ensure visual coverage of the
area around the source vessel.
Applicants must account for these
requirements in selecting vessels that
will be suitable for their planned
surveys. The Associations’ third point
contains an apparent misconception, in
that not all PSOs must have a minimum
of 90 days at-sea experience, with no
more than 18 months elapsed since the
conclusion of the relevant experience.
As described in our Notice of Proposed
IHAs and herein, a minimum of one
visual PSO and two acoustic PSOs must
have such experience (rather than all
PSOs). The Associations also apparently
believe that a requirement for
professional biological observers to be
‘‘trained biologists with experience or
training in the field identification of
marine mammals, including the
identification of behaviors’’ is a ‘‘rigid
restriction.’’ We respectfully disagree
with these claims, and note that no
labor shortage was experienced in the
Gulf of Mexico during 2013–2015 when
a significantly greater amount of survey
activity (i.e., as many as 30 source
vessels) was occurring than is
considered here, with requirements
similar to those described here. NMFS
has discussed the PSO requirements
specified herein with the Bureau of
Safety and Environmental Enforcement
(BSEE) and with third-party observer
providers; these parties have indicated
that the requirements should not be
expected to result in any labor shortage.
Comment: The Associations
recommend that passive acoustic
monitoring should be optional, citing
operational costs. ION also challenges
the efficacy of PAM.
Response: We agree with the
Associations that PAM complements
(rather than replaces) traditional visual
monitoring. However, it is now
considered to be a critical component of
real-time mitigation monitoring in the
majority of circumstances for deep
penetration airgun surveys. Acoustic
monitoring supplants visual monitoring
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during periods of poor visibility and
supplements during periods of good
visibility. As such, we strongly disagree
with the Associations’ outdated
recommendation.
There are multiple explanations of
how marine mammals could be in a
shutdown zone and yet go undetected
by observers. Animals are missed
because they are underwater
(availability bias) or because they are
available to be seen, but are missed by
observers (perception and detection
biases) (e.g., Marsh and Sinclair, 1989).
Negative bias on perception or detection
of an available animal may result from
environmental conditions, limitations
inherent to the observation platform, or
observer ability. Species vary widely in
the inherent characteristics that inform
expected bias on their availability for
detection or the extent to which
availability bias is convolved with
detection bias (e.g., Barlow and Forney
(2007) estimate probabilities of
detecting an animal directly on a
transect line (g(0)), ranging from 0.23 for
small groups of Cuvier’s beaked whales
to 0.97 for large groups of dolphins).
Typical dive times range widely, from
just a few minutes to more than 45
minutes for sperm whales (Jochens et
al., 2008; Watwood et al., 2006), while
g(0) for cryptic species such as Kogia
spp. declines more rapidly with
increasing Beaufort sea state than it does
for other species (Barlow, 2015). Barlow
and Gisiner (2006) estimated that when
weather and daylight considerations
were taken into account, visual
monitoring would detect fewer than two
percent of beaked whales that were
directly in the path of the ship. PAM
can be expected to improve on that
performance, and has been used
effectively as a mitigation tool by
operators in the Gulf of Mexico since at
least 2012.
We expect that PAM technology will
continue to develop and improve, and
look forward in the near-term to the
establishment of formal standards
regarding specifications for hardware,
software, and operator training
requirements, under the auspices of the
Acoustical Society of America’s (ASA)
Accredited Standards Committee on
Animal Bioacoustics (ANSI S3/SC1/
WG3; ‘‘Towed Array Passive Acoustic
Operations for Bioacoustics
Applications’’). In short, we expect that
PAM will continue to be an integral
component of mandatory mitigation
monitoring for deep penetration airgun
surveys conducted in compliance with
the MMPA.
Comment: Several industry
commenters expressed concern
regarding the potential for a large
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amount of shutdowns due to acoustic
detections of marine mammals in
circumstances where the PAM operator
is unable to identify the detected
species or is unable to determine the
location of the detected species in
relation to the relevant exclusion zone.
Response: NMFS recognizes these
concerns, and appreciates the
comments; however, these potential
outcomes would be contrary to NMFS’s
intent in prescribing the use of PAM.
Upon review of these comments, we
find that our description of PAM use
was unclear and offer clarification here.
In the event of acoustic detection,
shutdown must be implemented only
when the PAM operator determined, on
the basis of best professional judgment,
that shutdown is required for the
detected species and that the species is
likely within the relevant exclusion
zone. For example, although shutdown
is required for certain genera of large
delphinids, we do not require shutdown
upon acoustic detection of any
delphinid, as we do not expect that a
PAM operator would likely be capable
of distinguishing a detected delphinid
to species. As in all cases, the detection
would be communicated to visual
observers (if on duty); if the detected
animal(s) are observed visually,
shutdown may be required depending
on the species. Similarly, we clarify that
the shutdowns required upon
observation of a large whale with calf or
an aggregation of six or more large
whales are for visual observation only;
a PAM operator cannot be expected to
determine on the basis of acoustic
detection whether a detected whale is
with calf or is part of an aggregation of
six or more. Our intent is not to be
overly prescriptive, but to empower
trained PAM operators to employ
professional judgment in determining
whether shutdown is required in the
event of acoustic detection. That is, we
neither require precautionary
shutdowns based on acoustic detections
when either the species or location
cannot be determined, nor do we
require absolute certainty that the
detected animal is within the relevant
exclusion zone if the PAM operator
determines that the animal is most
likely within the zone on the basis of
professional judgment.
Comment: ION recommends that
NMFS extend the timeframe for
operation of the acoustic source during
repair of the PAM system in the event
of malfunction.
Response: We believe that the
requirements regarding conditions
under which a survey is allowed to
continue in the event of PAM
malfunction are appropriate. These
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conditions, which are based on
established protocols required in New
Zealand, have been implemented in
other locations with no known reports
of undue hardship. We also note that
ION does not recommend any
alternative. We will be open to
considering alternatives in the future,
but retain these requirements here.
Comment: ION questions NMFS’s
intentions regarding pre-clearance
requirements at nighttime, requesting
that NMFS clarify that observation with
PAM satisfies this requirement.
Response: Ramp-up of the acoustic
source, when necessary, may occur at
times of poor visibility (including
nighttime), assuming that a preclearance period has been observed. If
the pre-clearance period occurs at
nighttime, the pre-clearance watch
would be conducted only by the
acoustic observer. We clarify that,
indeed, observation with PAM satisfies
the pre-clearance watch requirement at
night.
Comment: TGS requests clarification
of what they interpret as contradictory
instructions with regard to when visual
observations must occur.
Response: We clarify here that visual
observation, i.e., two visual PSOs on
duty, is required during all daylight
hours (30 minutes prior to sunrise
through 30 minutes following sunset,
regardless of visibility) when use of the
acoustic source is planned, from 30
minutes prior to ramp-up through one
hour after ceasing use of the source (or
until 30 minutes after sunset). In
addition, visual observation is to occur
30 minutes prior to and during
nighttime ramp-up.
Comment: NRDC suggests that NMFS
should consider requiring use of
thermal detection as a supplement to
visual monitoring.
Response: We appreciate the
suggestion and agree that relatively new
thermal detection platforms have shown
promising results. Following review of
NRDC’s letter, we considered these and
other supplemental platforms as
suggested. However, to our knowledge,
there is no clear guidance available for
operators regarding characteristics of
effective systems, and the detection
systems cited by NRDC are typically
extremely expensive, and are therefore
considered impracticable for use in
most surveys. For example, one system
cited by NRDC (Zitterbart et al., 2013)—
a spinning infrared camera and an
algorithm that detects whale blows on
the basis of their thermal signature—
was tested through funding provided by
the German government and, according
to the author at a 2015 workshop
concerning mitigation and monitoring
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for seismic surveys, the system costs
hundreds of thousands of dollars. We
are not aware of its use in any
commercial application. Further, these
systems have limitations, as
performance may be limited by
conditions such as fog, precipitation,
sea state, glare, water- and airtemperatures and ambient brightness,
and the successful results obtained to
date reflect a limited range of
environmental conditions and species.
NRDC does not provide specific
suggestions with regard to
recommended systems or characteristics
of systems. We do not consider
requirements to use systems such as
those recommended by NRDC to
currently be practicable.
Comment: Mysticetus, LLC
(Mysticetus) recommends that all
operators be required to use a ‘‘modern
PSO software system’’ for structured
data collection, real-time situational
awareness and computerized mitigation
decision support. They also list their
recommended minimum requirements
for a PSO software system. Mysticetus
also recommends the creation of a
centralized cloud-based database to
hold all PSO-gathered data from all
survey operations, and states that it
should be a requirement of all operators
to have their PSO software
automatically upload data to this system
on a regular schedule. Separately, we
received a comment letter from P.N.
Halpin of Duke University’s Marine
Geospatial Ecology Lab; the commenter
provides support for the
recommendation to create a cloud-based
storage system to store and provide
public access to PSO data and confirms
that the OBIS–SEAMAP team has agreed
in principle to host and disseminate
such a proposed database. Mysticetus
goes on to provide a number of detailed
recommendations relating to how our
notice might describe the capabilities of
a PSO software system, such as is
recommended for mandatory use, in
relation to our proposed mitigation and
monitoring requirements.
Response: We appreciate commenters’
careful attention to improvement of
required mitigation and monitoring and
for their recommendations. We also
appreciate the capabilities of ‘‘modern
PSO software’’ described by Mysticetus,
including the Mysticetus System
marketed by Mysticetus, LLC. We agree
that such systems may be advantageous
for the operators, as well as for NMFS
and for the public. However, we
disagree that NMFS must mandate that
one specific software system be used to
accomplish the goals of the required
mitigation and monitoring, so long as
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the requirements for mitigation,
monitoring, and reporting are met.
Comment: The MMC stated that it
supports our proposed requirement
relating to corrections of sightings data
using detection probabilities, in order to
estimate numbers of actual incidents of
marine mammal take. However, the
MMC also suggests that our proposed
use of Carr et al. (2011) is not the most
appropriate source of such probability
values, and suggests that we instead
base this approach on Barlow (2015). In
addition, the MMC points out that we
did not explicitly state that we also
intend to account for unobserved areas,
and provided a recommended
extrapolation method.
Response: We agree with the MMC’s
statements on this topic and thank them
for the helpful suggestions. Although,
after review of public comments, we do
not require the applicants to conduct
these analyses themselves (described in
greater detail in the section entitled
‘‘Monitoring and Reporting’’), we intend
to adopt the MMC’s recommended
approach in performing this analysis.
We will report these corrected results in
association with comprehensive
reporting from the applicants.
Comment: NRDC asserts that NMFS
fails to prescribe requirements sufficient
to monitor and report takings of marine
mammals, and further draws a
comparison to ‘‘related compliance in
the Gulf of Mexico’’ where they state
that ‘‘BOEM is developing an adaptive
management program, which, beyond
‘the standard’ safety zone monitoring
and reporting requirements, may
include ‘visual or acoustic observation
of animals, new or ongoing research and
data analysis, in situ measurements of
sound sources’ . . . .’’ Multiple
commenters suggested that monitoring
plans should be designed and
coordinated across surveys.
Commenters also noted that there are
many research gaps that need to be
filled, and suggested that NMFS should
include monitoring requirements that
fill those gaps—such as marine mammal
habitat use, abundance surveys,
masking, mysticete hearing ranges,
behavioral response thresholds,
ecosystem-wide impacts, and the
efficacy of mitigation measures. Specific
recommendations included acoustic
receivers outside the survey area to
allow for recording and assessment
before, during, and after surveys, as well
as aerial surveys to evaluate platformbased visual monitoring.
Response: Section 101(a)(5)(D) of the
MMPA indicates that any authorization
NMFS issues shall include
‘‘requirements pertaining to the
monitoring and reporting of such taking
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63313
by harassment.’’ This broad requirement
allows for a high degree of flexibility in
what NMFS may accept or include as a
monitoring requirement, but is not
specific in identifying a threshold of
what should be considered adequate
monitoring. Contrary to NRDC’s
comments, except for IHAs in Arctic
waters, NMFS’s implementing
regulations do not provide a specific
standard regarding what required
monitoring and reporting measures
‘‘must’’ accomplish. However, they do
direct that ‘‘requests,’’ i.e., the materials
submitted by applicants, should include
‘‘the suggested means of accomplishing
the necessary monitoring and reporting
that will result in increased knowledge
of the species, the level of taking or
impacts on populations of marine
mammals that are expected to be
present while conducting activities, and
suggested means of minimizing burdens
by coordinating such reporting
requirements with other schemes
already applicable to persons
conducting such activity.’’ NRDC
further extracts pieces of this language
to suggest that in the case of these five
applicants, they are required to
coordinate with each other’s monitoring
efforts, ignoring the fact that the
regulation points to this coordination
only in support of minimizing the
burden on the applicant and that it
refers to coordination with ‘‘schemes
already applicable to persons
conducting such activity,’’ of which
there are currently none. NRDC attempts
to further this argument that
coordination across projects is required
by statute by pointing to a compliance
scheme that they state is in
development for the Gulf of Mexico.
However, as described elsewhere in
this document, section 101(a)(5)(D) of
the MMPA indicates that the analysis,
the findings, and any requirements
included in the development of an IHA
pertain only to the specified activity—
specifically, NMFS is required to
include the ‘‘requirements pertaining to
the monitoring and reporting of such
taking by harassment’’ (referring to the
taking authorized in the IHA). Notably,
section 101(a)(5)(A), which applies in
the case of NMFS’s incidental take
regulations for a specified activity for up
to five years, contains similar
requirements, but the requirements
apply to the entirety of the activities
covered under any incidental take
rulemaking. Indeed, NMFS’s
implementing regulations indicate that
‘‘for all petitions for regulations [ . . .
] applicants must provide the
information requested in 216.104 on
their activity as a whole.’’ Therefore, it
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is appropriate that a monitoring plan
developed in support of BOEM’s
requested rulemaking to cover
incidental take from activities covered
by their oil and gas program in the Gulf
of Mexico would address, and
potentially coordinate across, multiple
surveys.
Although the statute provides
flexibility in what constitutes acceptable
monitoring and reporting measures
(increased knowledge of the species and
the taking), NMFS’s implementing
regulations provide additional guidance
as to what an applicant should submit
in their requests, indicating ‘‘Monitoring
plans should include a description of
the techniques that would be used to
determine the movement and activities
of marine mammals near the activity
site(s) including migration and habitat
uses, such as feeding.’’ We appreciate
the recommendations provided by the
public, and agree that from a content
standpoint, many of the
recommendations could qualify as
appropriate monitoring for any of these
surveys. However, we note that many of
the monitoring recommendations
require a scale of effort that is not
commensurate to the scale of either the
underlying activities or the anticipated
impacts of the activities on marine
mammals covered by any single IHA. In
other words, many of the recommended
measures would necessitate complex
and expensive survey designs and
methods that would exceed the duration
of any one activity (e.g., regular
distribution and abundance surveys,
moored arrays for before/during/after
studies) and/or require levels of
collaboration, planning and permitting
(behavioral response studies, aerial
programs to evaluate mitigation
effectiveness) that are not reasonable in
the context of an activity that consists
of one mobile source moving across a
large area and that will last less than a
year and, further, is not appropriate in
the context of the comparatively smaller
scale of total surveys in the Atlantic at
the current time.
Most importantly, regardless of
whether other monitoring plans would
also suffice, we believe that the visual
and acoustic monitoring required for
each of these surveys meets the MMPA
requirement for monitoring and
reporting. NRDC implies that
monitoring within 1 km of the vessel is
not useful or adequate. First, the
required monitoring is not limited to
within a zone, as PSOs will record the
required information at whatever
distance they can accurately collect it—
and past monitoring reports from
similar platforms show useful data
collected beyond 1 km. Further, even if
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the PSOs cannot always see, or
acoustically monitor, the entire zone
within which take is estimated to occur,
the data collected will still be both
qualitatively and quantitatively
informative, as behaviors will be
detectable within these distances and
there are accepted methods for
extrapolating sightings data to make
inferences about larger areas. For these
surveys, the PSOs will gather detailed
information on the marine mammals
both sighted and acoustically detected,
their behaviors (different facets
detectable visually and acoustically)
and locations in relation to the sound
source, and the operating status of any
sound sources—allowing for a better
understanding of both the impacted
species as well as the taking itself.
Comment: Multiple commenters
provided various comments concerning
transparency and data sharing with
regard to data reported to NMFS.
Response: We agree with the overall
point and will make all data reported to
NMFS in accordance with IHA
requirements available for public review
following review and approval of
reports by NMFS. However, several
commenters were apparently confused
about the nature of data required to be
reported to NMFS and/or the
mechanism of reporting. For example,
Oceana stated that NMFS should ‘‘make
the seismic survey data available to
industry, government, and the public so
that all stakeholders can make an
informed cost-benefit analysis and
decide whether offshore drilling should
be allowed. . . .’’ However, the survey
data apparently referenced by Oceana is
not required to be provided by the
applicants to NMFS, but is provided to
BOEM. Oceana also stated that NMFS
should ‘‘live stream data as often as
possible as well as archive the passive
acoustic monitoring feed.’’ Respectfully,
we are unclear as to what Oceana is
referring to.
Comment: Several industry
commenters took issue with the 15-km
buffers that NMFS understands will be
required around National Marine
Sanctuaries.
Response: We described these
requirements, which are a product of
discussions between BOEM and
NOAA’s Office of National Marine
Sanctuaries, in our Notice of Proposed
IHAs solely for purposes of
thoroughness. Here, we clarify that this
standoff distance is not a requirement of
NMFS and will not be included in any
issued IHAs. As such, criticisms of this
requirement (which we expect to be
included as conditions in permits
issued by BOEM) are not relevant here
and we do not respond to them.
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Comment: A few commenters
suggested that NMFS should fully
implement NOAA’s Ocean Noise
Strategy, which they interpreted as
meaning that certain knowledge gaps on
marine mammals and noise must be
filled before NMFS may issue these
IHAs. Another commenter said that to
help support implementation of the
Ocean Noise Strategy Roadmap
(cetsound.noaa.gov/Assets/cetsound/
documents/Roadmap/ONS_Roadmap_
Final_Complete.pdf), the agencies (i.e.,
NOAA and BOEM) should undertake
efforts to evaluate impacts to marine
mammal habitat before, during, and
after surveys occur.
Response: NMFS appreciates the
support for the Ocean Noise Strategy
and agrees with the goal of focusing
both agency science and agencyrequired monitoring towards filling
known gaps in our understanding of the
effects of noise on marine mammals
wherever possible and appropriate. The
Ocean Noise Strategy does not mandate
any specific actions, though; rather, it
directs NOAA to use our existing
authorities and capacities to focus on
the management, science, decisionmaking tool, and outreach goals
outlined in the Roadmap. In the case of
MMPA incidental take authorizations,
NMFS must abide by statutory directive,
and we have described above (both in
comment response and elsewhere in the
body of this Notice) our rationale for
including the monitoring and reporting
measures in these IHAs. In the context
of MMPA authorizations, it is typically
easier to apply some of the monitoring
and research goals articulated in the
Ocean Noise Strategy through section
101(a)(5)(A) rulemaking, as the
expanded scope and longer duration of
the coverage period are better suited to
more complex, large-scale, or expensive
approaches (e.g., such as those utilized
for U.S. Navy training and testing
incidental take regulations).
National Environmental Policy Act
Comment: NRDC and Oceana provide
a litany of complaints regarding the
sufficiency of BOEM’s EIS and its
suitability for supporting NMFS’s
decision analysis, and state that NMFS
must prepare a separate analysis before
taking action.
Response: Following independent
evaluation of BOEM’s EIS, and review of
public comments, NMFS determined
BOEM’s 2014 Final PEIS to be
comprehensive in analyzing the broad
scope of potential survey activities, and
that the evaluation of the direct,
indirect, and cumulative impacts on the
human environment, including the
marine environment, is adequate to
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support NMFS’s consideration for future
issuance of ITAs to geophysical
companies and other potential
applicants through tiering and
incorporation by reference. NMFS
further determined that subsequent
issuance of ITAs for survey activities is
likely to fall within the scope of the
analysis in the 2014 Final PEIS,
particularly since the impacts of the
alternatives evaluated by BOEM (1)
assess impact over a much longer period
of time (i.e., nine years) than is analyzed
by NMFS for any given ITA, (2)
encompass many of the same factors
NMFS historically considered when
reviewing ITAs for geophysical surveys
or related activity (i.e., marine mammal
exposures, intensity of acoustic
exposure, monitoring and mitigation
factors, and more), and (3) are
substantially the same as the impacts of
NMFS’s issuance of any given ITA for
take of marine mammals incidental to
future applicants’ survey activities. The
2014 Final PEIS also addresses NOAA’s
required components for adoption as it
meets the requirements for an adequate
EIS under the CEQ regulations (40 CFR
part 1500–1508) and NOAA
Administrative Order 216–6A and
reflects comments and expert input
provided by NOAA as a cooperating
agency. Therefore, NMFS subsequently
signed a Record of Decision that: (1)
Adopted the Final PEIS to support
NMFS’s analysis associated with
issuance of ITAs pursuant to sections
101(a)(5)(A) or (D) of the MMPA and the
regulations governing the taking and
importing of marine mammals (50 CFR
part 216), and (2) in accordance with 40
CFR 1505.2, announced and explained
the basis for NMFS’s decision to review
and potentially issue ITAs under the
MMPA on a case-by-case basis, if
appropriate, guided by the analyses in
the Final PEIS and mitigation measures
specified in BOEM’s 2014 ROD.
However, following review of public
comments, NMFS agrees with NRDC
and other commenters who suggested
that it would not be appropriate for
NMFS to simply adopt BOEM’s EIS (our
stated approach in the Notice of
Proposed IHAs). Although we disagree
with claims that the EIS is deficient, it
is appropriate to evaluate whether
supplementation is necessary. In so
doing, we consider (1) whether new
information not previously considered
in the EIS is now available; (2) whether
that new information may change the
impact analysis contained in the EIS;
and (3) whether our impact conclusions
may change as a result of the new
information and new impact analyses.
However, we further consider that the
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EIS was purposely developed so that
additional information could be
included in subsequent NEPA
evaluations. Because we determined
that relevant new information was in
fact available, in addition to applicantspecific details, we determined it
appropriate to conduct a supplemental
Environmental Assessment.
NMFS determined that conducting
NEPA review and preparing a tiered EA
is appropriate to analyze environmental
impacts associated with NMFS’s
issuance of separate IHAs to five
different companies. NMFS further
determined that the issuance of these
five IHAs are ‘‘similar’’ but not
‘‘connected actions’’ per 40 CFR
1508.25(a)(3) due to general
commonalities in geography, timing,
and type of activity, which provides a
reasonable basis for evaluating them
together in a single environmental
analysis. The EA also incorporates
relevant portions of BOEM’s Final PEIS
while focusing analysis on
environmental issues specific to the five
IHAs. NMFS has completed the
necessary environmental analysis under
NEPA.
Miscellaneous
Comment: Several commenters
suggest that NMFS should require the
applicants to consolidate their surveys.
Response: Requiring individual
applicants to alter their survey
objectives and/or design does not fall
within NMFS’s authority. Moreover,
though these multiple concurrent
surveys are perceived as ‘‘duplicative,’’
they are in fact designed specifically to
produce proprietary data that satisfies
the needs of survey funders. As is the
current practice in the Gulf of Mexico,
it is within BOEM’s jurisdiction as the
permitting agency to require permit
applicants to submit statements
indicating that existing data are not
available to meet the data needs
identified for the applicant’s survey
(i.e., non-duplicative survey statement),
but such requirements are not within
NMFS’s purview. For example, NRDC
claims erroneously that NMFS ‘‘has
authority under the mitigation provision
of the MMPA to consider directing the
companies to consolidate their
surveys,’’ placing such a requirement
under the auspices of practicability.
Leaving aside that directing any given
applicant to abandon their survey plans
would not in fact be practicable, it is
inappropriate to consider this suggested
requirement through that lens.
Similarly, the MMC vaguely references
section 101(a)(5)(A)(i)(II)(aa) in stating
that NMFS is provided authority to
require such consolidation—we assume
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63315
that MMC intended to reference the
parallel language at section
101(a)(5)(D)(ii)(I), which states only that
NMFS shall prescribe the ‘‘means of
effecting the least practicable impact on
such species or stock and its habitat.’’
NMFS considers the specified activity
described by an applicant in reviewing
a request for an incidental take
authorization; nothing in the statute
provides authority to direct
consolidation of independent specified
activities (regardless of any presumption
of duplication, about which NMFS is
not qualified to judge).
The MMC specifically cites a number
of collaborative surveys conducted in
foreign waters, and recommends that
NMFS ‘‘work with BOEM’’ to require
such collaboration. However, MMC
provides no useful recommendations as
to how such collaboration might be
achieved. Given the absence of
appropriate statutory authority, we
recommend that the MMC itself
undertake to foster such collaboration
between geophysical data acquisition
companies and relevant Federal
agencies as it deems necessary to protect
and conserve marine mammals. NMFS
looks forward to joining in such an
MMC-led collaboration, as appropriate.
We also note that industry
commenters stated, anticipating
suggestions of this sort, that such
recommendations ‘‘are based upon a
substantial misunderstanding of
important technical, operational, and
economic aspects of seismic surveying.’’
These commenters also noted that,
based on the findings of an expert panel
recently convened by BOEM to study
the issue of duplicative surveys (see
Appendix L in BOEM, 2017), none of
the surveys considered here would meet
the definition established for a
‘‘duplicate’’ survey.
Comment: NRDC contends that NMFS
must consider a standard requiring
analysis and selection of minimum
source levels. In furtherance of this
overall quieting goal, NRDC also states
that NMFS should consider requiring
that all vessels employed in the survey
activities undergo regular maintenance
to minimize propeller cavitation and be
required to employ the best shipquieting designs and technologies
available for their class of ship, and that
we should require these vessels to
undergo measurement for their
underwater noise output.
Response: An expert panel convened
by BOEM to determine whether it
would be feasible to develop standards
to determine a lowest practicable source
level has determined that it would not
be reasonable or practicable to develop
such metrics (see Appendix L in BOEM,
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2017). We appreciate that NRDC
disagrees with the panel’s findings, but
we do not believe it appropriate to
address these grievances to NMFS.
NRDC further claims that NMFS’s
deference to the findings of an expert
panel convened specifically to consider
this issue is ‘‘arbitrary under the
MMPA.’’ The bulk of NRDC’s comment
appears to be addressed to BOEM, and
we encourage NRDC to engage with
BOEM regarding these supposed
shortcomings of the panel’s findings.
The subject matter is outside NMFS’s
expertise, and we have no basis upon
which to doubt the panel’s published
findings. We decline to address here the
ways in which NRDC claims that BOEM
misunderstood the issue.
With regard to the recommended
requirements to measure or control
vessel noise, or to make some minimum
requirements regarding the design of
vessels used in the surveys, we disagree
that these requirements would be
practicable. While we agree that vessel
noise is of concern in a cumulative and
chronic sense, it is not of substantial
concern in relation to the MMPA’s least
practicable adverse impact standard,
given the few vessels used in any given
specified activity. NMFS looks forward
to continued collaboration with NRDC
and others towards ship quieting.
Description of Marine Mammals in the
Area of the Specified Activities
We refer readers to NMFS’s Stock
Assessment Reports (SAR;
www.fisheries.noaa.gov/national/
marine-mammal-protection/marinemammal-stock-assessments), species
descriptions provided on NMFS’s
website (www.fisheries.noaa.gov/findspecies), and to the applicants’ species
descriptions (Sections 3 and 4 of the
applications). These sources summarize
available information regarding physical
descriptions, status and trends,
distribution and habitat preferences,
behavior and life history, and auditory
capabilities of the potentially affected
species, and are not reprinted here.
Table 2 lists all species with expected
potential for occurrence in the mid- and
south Atlantic and summarizes
information related to the population or
stock, including potential biological
removal (PBR). For taxonomy, we follow
Committee on Taxonomy (2017). PBR,
defined by the MMPA as the maximum
number of animals, not including
natural mortalities, that may be removed
from a marine mammal stock while
allowing that stock to reach or maintain
its optimum sustainable population, is
considered in concert with known
sources of ongoing anthropogenic
mortality (as described in NMFS’s
SARs). For status of species, we provide
information regarding U.S. regulatory
status under the MMPA and ESA.
Marine mammal abundance estimates
presented in this document represent
the total number of individuals that
make up a given stock or the total
number estimated within a particular
study area. NMFS’s stock abundance
estimates for most species represent the
total estimate of individuals within the
geographic area, if known, that
comprises that stock. For some species,
this geographic area may extend beyond
U.S. waters. Survey abundance (as
compared to stock or species
abundance) is the total number of
individuals estimated within the survey
area, which may or may not align
completely with a stock’s geographic
range as defined in the SARs. These
surveys may also extend beyond U.S.
waters.
In some cases, species are treated as
guilds. In general ecological terms, a
guild is a group of species that have
similar requirements and play a similar
role within a community. However, for
purposes of stock assessment or
abundance prediction, certain species
may be treated together as a guild
because they are difficult to distinguish
visually and many observations are
ambiguous. For example, NMFS’s
Atlantic SARs assess Mesoplodon spp.
and Kogia spp. as guilds. Here, we
consider pilot whales, beaked whales
(excluding the northern bottlenose
whale), and Kogia spp. as guilds. In the
following discussion, reference to ‘‘pilot
whales’’ includes both the long-finned
and short-finned pilot whale, reference
to ‘‘beaked whales’’ includes the
Cuvier’s, Blainville’s, Gervais,
Sowerby’s, and True’s beaked whales,
and reference to ‘‘Kogia spp.’’ includes
both the dwarf and pygmy sperm whale.
Thirty-four species (with 39 managed
stocks) are considered to have the
potential to co-occur with the planned
survey activities. Species that could
potentially occur in the survey areas but
are not expected to have reasonable
potential to be harassed by any survey
are omitted from further analysis. These
include extralimital species, which are
species that do not normally occur in a
given area but for which there are one
or more occurrence records that are
considered beyond the normal range of
the species. Extralimital species or
stocks unlikely to co-occur with survey
activity include nine estuarine
bottlenose dolphin stocks, four
pinniped species, the white-beaked
dolphin (Lagenorhynchus albirostris),
and the beluga whale (Delphinapterus
leucas). For detailed discussion of these
species, please see our Federal Register
Notice of Proposed IHAs (82 FR 26244;
June 6, 2017). In addition, the West
Indian manatee (Trichechus manatus
latirostris) may be found in coastal
waters of the Atlantic. However,
manatees are managed by the U.S. Fish
and Wildlife Service and are not
considered further in this document. All
managed stocks in this region are
assessed in NMFS’s U.S. Atlantic SARs.
All values presented in Table 2 are the
most recent available at the time of
publication and are available in the
2017 SARs (Hayes et al., 2018a) and
draft 2018 SARs (available online at:
www.fisheries.noaa.gov/national/
marine-mammal-protection/draftmarine-mammal-stock-assessmentreports).
TABLE 2—MARINE MAMMALS POTENTIALLY PRESENT IN THE VICINITY OF SURVEY ACTIVITIES
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Common name
Scientific name
ESA/
MMPA
status;
strategic
(Y/N) 1
Stock
Predicted
mean (CV)/
maximum
abundance 3
NMFS stock abundance
(CV, Nmin, most recent
abundance survey) 2
Predicted
abundance
outside
EEZ 4
PBR
Annual
M/SI
(CV) 5
Order Cetartiodactyla—Cetacea—Superfamily Mysticeti (baleen whales)
Family Balaenidae:
North Atlantic right
whale.
Family Balaenopteridae
(rorquals):
Humpback whale ...
VerDate Sep<11>2014
Eubalaena glacialis ......
Western North Atlantic
(WNA).
E/D; Y
451 (n/a; 445; n/a) .......
394 (0.07) * ...
1
0.9
5.56
Megaptera
novaeangliae
novaeangliae.
Gulf of Maine ...............
-; N
896 (n/a; 896; 2015) ....
1,637 (0.07) */
1,994.
8
14.6
9.8
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TABLE 2—MARINE MAMMALS POTENTIALLY PRESENT IN THE VICINITY OF SURVEY ACTIVITIES—Continued
Common name
ESA/
MMPA
status;
strategic
(Y/N) 1
Predicted
mean (CV)/
maximum
abundance 3
NMFS stock abundance
(CV, Nmin, most recent
abundance survey) 2
Predicted
abundance
outside
EEZ 4
PBR
Annual
M/SI
(CV) 5
Scientific name
Stock
Canadian East Coast ...
-; N
2,591 (0.81; 1,425;
2011).
2,112 (0.05) */
2,431.
929
14
7.5
Bryde’s whale ........
Sei whale ...............
Balaenoptera
acutorostrata
acutorostrata.
B. edeni brydei .............
B. borealis borealis ......
None defined 6 .............
Nova Scotia .................
-; n/a
E/D; Y
n/a ................................
357 (0.52; 236; 2011) ..
7
46
n/a
0.5
n/a
0.6
Fin whale ...............
B. physalus physalus ...
WNA .............................
E/D; Y
44
2.5
2.5
Blue whale .............
B. musculus musculus
WNA .............................
E/D; Y
1,618 (0.33; 1,234;
2011).
Unknown (n/a; 440; n/
a).
7 (0.58)/n/a ...
717 (0.30) */
1,519.
4,633 (0.08)/
6,538.
11 (0.41)/n/a
4
0.9
Unk.
Minke whale ...........
Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
Family Physeteridae:
Sperm whale ..........
Family Kogiidae:
Pygmy sperm
whale.
Dwarf sperm whale
Family Ziphiidae
(beaked whales):
Cuvier’s beaked
whale.
Gervais beaked
whale.
Blainville’s beaked
whale.
Sowerby’s beaked
whale.
True’s beaked
whale.
Northern bottlenose
whale.
Family Delphinidae:
Rough-toothed dolphin.
Common bottlenose
dolphin.
North Atlantic ...............
E/D; Y
2,288 (0.28; 1,815;
2011).
5,353 (0.12)/
7,193.
2,456
3.6
0.8
Kogia breviceps ...........
WNA .............................
-; N
3,785 (0.47; 2,598;
2011) 7.
678 (0.23)/n/
a 7.
428
21
3.5 (1.0)
K. sima .........................
WNA .............................
-; N
Ziphius cavirostris ........
WNA .............................
-; N
14,491 (0.17)/
16,635 7.
9,426
50
0.4
Mesoplodon europaeus
WNA .............................
-; N
6,532 (0.32; 5,021;
2011).
7,092 (0.54; 4,632;
2011) 7.
46
0.2
M. densirostris ..............
WNA .............................
-; N
M. bidens .....................
WNA .............................
-; N
M. mirus .......................
WNA .............................
-; N
Hyperoodon ampullatus
WNA .............................
-; N
Unknown ......................
90 (0.63)/n/a
11
Undet.
0
Steno bredanensis .......
WNA .............................
-; N
136 (1.0; 67; 2016) ......
532 (0.36)/n/a
313
0.7
0
Tursiops truncatus
truncatus.
WNA Offshore ..............
WNA Coastal, Northern
Migratory.
-; N
D; Y
77,532 (0.40; 56,053;
2011).
6,639 (0.41; 4,759; ......
2016) ............................
97,476 (0.06)/
144,505 7.
5,280
561
48
D; Y
D; Y
3,751 (0.60; 2,353;
2016).
6,027 (0.34; 4,569;
2016).
877 (0.49; 595; 2016) ..
1,218 (0.35; 913; 2016)
39.4
(0.29)
6.1
(0.32)–
13.2
(0.22)
0–14.3
(0.31)
1.4–1.6
-; N
Clymene dolphin ....
Stenella clymene ..........
WNA Coastal, Southern
Migratory.
WNA Coastal, South
Carolina/Georgia.
WNA Coastal, Northern
Florida.
WNA Coastal, Central
Florida.
WNA .............................
Atlantic spotted dolphin.
Pantropical spotted
dolphin.
Spinner dolphin ......
S. frontalis ....................
WNA .............................
-; N
S. attenuata attenuata
WNA .............................
-; N
S. longirostris
longirostris.
S. coeruleoalba ............
WNA .............................
-; N
WNA .............................
-; N
Striped dolphin .......
Common dolphin ....
Fraser’s dolphin .....
Atlantic white-sided
dolphin.
Risso’s dolphin .......
amozie on DSK3GDR082PROD with NOTICES2
Physeter
macrocephalus.
Melon-headed
whale.
Pygmy killer whale
False killer whale ...
Killer whale ............
Short-finned pilot
whale.
Long-finned pilot whale
VerDate Sep<11>2014
D; Y
D; Y
Delphinus delphis delphis.
Lagenodelphis hosei ....
Lagenorhynchus acutus
WNA .............................
-; N
WNA .............................
WNA .............................
-; N
-; N
Grampus griseus ..........
WNA .............................
-; N
Peponocephala electra
WNA .............................
-; N
Feresa attenuata ..........
Pseudorca crassidens ..
Orcinus orca .................
Globicephala
macrorhynchus.
G. melas melas ............
WNA
WNA
WNA
WNA
-;
-;
-;
-;
18:20 Dec 06, 2018
Jkt 247001
.............................
.............................
.............................
.............................
WNA .............................
PO 00000
Frm 00051
N
Y
N
N
-; N
Fmt 4701
23
46
6
9.1
0.6
0.4
6,086 (0.93; 3,132;
1998) 8.
44,715 (0.43; 31,610;
2011).
3,333 (0.91; 1,733;
2011).
Unknown ......................
12,515 (0.56)/
n/a.
55,436 (0.32)/
137,795.
4,436 (0.33)/
n/a.
262 (0.93)/n/a
11,503
Undet.
0
7,339
316
0
2,781
17
0
184
Undet.
0
54,807 (0.3; 42,804;
2011).
70,184 (0.28; 55,690;
2011).
Unknown ......................
48,819 (0.61; 30,403;
2011).
18,250 (0.46; 12,619;
2011).
Unknown ......................
75,657 (0.21)/
172,158.
86,098 (0.12)/
129,977.
492 (0.76)/n/a
37,180 (0.07)/
59,008.
7,732 (0.09)/
18,377.
1,175 (0.50)/
n/a.
n/a .................
95 (0.84)/n/a
11 (0.82)/n/a
18,977 (0.11)/
35,715 6.
15,166
428
0
3,154
557
474
368
Undet.
304
1,060
126
1,095
Undet.
406
(0.10)
0
57
(0.15)
49.9
(0.24)
0
n/a
35
4
2,258
Undet.
2.1
Undet.
236
Unknown ......................
442 (1.06; 212; 2011) ..
Unknown ......................
28,924 (0.24; 23,637;
2016).
5,636 (0.63; 3,464;
2011).
Sfmt 4703
E:\FR\FM\07DEN2.SGM
35
07DEN2
0
Unk.
0
168
(0.13)
27
(0.18)
63318
Federal Register / Vol. 83, No. 235 / Friday, December 7, 2018 / Notices
TABLE 2—MARINE MAMMALS POTENTIALLY PRESENT IN THE VICINITY OF SURVEY ACTIVITIES—Continued
Common name
Family Phocoenidae
(porpoises):
Harbor porpoise .....
Scientific name
ESA/
MMPA
status;
strategic
(Y/N) 1
Stock
Phocoena phocoena
phocoena.
Gulf of Maine/Bay of
Fundy.
-; N
Predicted
mean (CV)/
maximum
abundance 3
NMFS stock abundance
(CV, Nmin, most recent
abundance survey) 2
79,833 (0.32; 61,415;
2011).
45,089
(0.12) */
50,315.
Predicted
abundance
outside
EEZ 4
91
PBR
706
Annual
M/SI
(CV) 5
255
(0.18)
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1 Endangered Species Act (ESA) status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-) indicates that the species is not listed under the
ESA or designated as depleted under the MMPA. Under the MMPA, a strategic stock is one for which the level of direct human-caused mortality exceeds PBR or
which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed under the ESA is automatically
designated under the MMPA as depleted and as a strategic stock.
2 NMFS marine mammal stock assessment reports online at: www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments. CV is
coefficient of variation; Nmin is the minimum estimate of stock abundance. In some cases, CV is not applicable. For the right whale, the best abundance value is
based on a model of the sighting histories of individually identifiable animals (as of October 2017). The model of these histories produced a median abundance value
of 451 whales (95 percent credible intervals 434–464). The minimum estimate of 440 blue whales represents recognizable photo-identified individuals.
3 This information represents species- or guild-specific abundance predicted by habitat-based cetacean density models (Roberts et al., 2016). For the North Atlantic
right whale, we report the outputs of a more recently updated model (Roberts et al., 2017). These models provide the best available scientific information regarding
predicted density patterns of cetaceans in the U.S. Atlantic Ocean, and we provide the corresponding mean annual and maximum monthly abundance predictions.
Total abundance estimates were produced by computing the mean density of all pixels in the modeled area and multiplying by its area. Roberts et al. (2016) did not
produce a density model for pygmy killer whales off the east coast. For those species marked with an asterisk, the available information supported development of either two or four seasonal models; each model has an associated abundance prediction. Here, we report the maximum predicted seasonal abundance.
4 The density models used to predict acoustic exposures (e.g., Roberts et al., 2016) provide abundance predictions for the area within the U.S. EEZ. However, the
model outputs were also extrapolated to the portion of the specific geographic region outside the EEZ in order to predict acoustic exposures in that area (i.e., from
200 nmi to 350 nmi offshore). Therefore, we calculated corresponding seasonal abundance estimates for this region. The maximum seasonal abundance estimate is
reported.
5 These values, found in NMFS’s SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined (e.g., commercial fisheries, ship strike). Annual M/SI often cannot be determined precisely and is in some cases presented as a minimum value or range. A CV associated with estimated
mortality due to commercial fisheries is presented in some cases.
6 Bryde’s whales are occasionally reported off the southeastern U.S. and southern West Indies. NMFS defines and manages a stock of Bryde’s whales that is resident in the northern Gulf of Mexico, but does not define a separate stock in the Atlantic Ocean.
7 Abundance estimates are in some cases reported for a guild or group of species when those species are difficult to differentiate at sea. Similarly, the habitatbased cetacean density models produced by Roberts et al. (2016) are based in part on available observational data which, in some cases, is limited to genus or guild
in terms of taxonomic definition. NMFS’s SARs present pooled abundance estimates for Kogia spp. and Mesoplodon spp., while Roberts et al. (2016) produced density models to genus level for Kogia spp. and Globicephala spp. and as a guild for most beaked whales (Ziphius cavirostris and Mesoplodon spp.). Finally, Roberts et
al. (2016) produced a density model for bottlenose dolphins that does not differentiate between offshore and coastal stocks.
8 NMFS’s abundance estimates for the Clymene dolphin is greater than eight years old and not considered current. PBR is therefore considered undetermined for
this stock, as there is no current minimum abundance estimate for use in calculation. We nevertheless present the most recent abundance estimate.
For the majority of species potentially
present in the specific geographic
region, NMFS has designated only a
single generic stock (e.g., ‘‘western
North Atlantic’’) for management
purposes. This includes the ‘‘Canadian
east coast’’ stock of minke whales,
which includes all minke whales found
in U.S. waters. For the humpback and
sei whales, NMFS defines stocks on the
basis of feeding locations, i.e., Gulf of
Maine and Nova Scotia, respectively.
However, our reference to humpback
whales and sei whales in this document
refers to any individuals of the species
that are found in the specific geographic
region. These individuals may be from
the same breeding population (e.g., West
Indies breeding population of
humpback whales) but visit different
feeding areas. For the bottlenose
dolphin, NMFS defines an oceanic stock
and multiple coastal stocks.
North Atlantic Right Whale—We
provide additional discussion of the
North Atlantic right whale in order to
address the current status of the species,
which has deteriorated since
publication of our Notice of Proposed
IHAs. The North Atlantic right whale
was severely depleted by historical
whaling, and was originally listed as
endangered under the ESA in 1970. The
right whale’s range historically
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18:20 Dec 06, 2018
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extended to the eastern North Atlantic,
as well as the Denmark Strait and waters
south of Greenland. However, sightings
of right whales beyond their current
western North Atlantic distribution are
rare and the eastern North Atlantic
population may be functionally extinct
(Kraus and Rolland, 2007; Best et al.,
2001). In the western North Atlantic, a
median abundance value of 451 whales
in October 2017 (as reported in NMFS’s
draft 2018 SARs and Table 2) based on
a Bayesian mark-recapture open
population model, which accounts for
individual differences in the probability
of being photographed (95 percent
credible intervals 434–464, Pace et al.,
2017). Accurate pre-exploitation
abundance estimates are not available
for either population of the species. The
western population may have numbered
fewer than 100 individuals by 1935,
when international protection for right
whales came into effect (Kenney et al.,
1995).
Modeling suggests that in 1980,
females had a life expectancy of
approximately 52 years of age (twice
that of males at the time) (Fujiwara and
Caswell, 2001). However, due to
reduced survival probability, in 1995
female life expectancy was estimated to
have declined to approximately 15
years, with males having a slightly
PO 00000
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Fmt 4701
Sfmt 4703
higher life expectancy into the 20s
(Fujiwara and Caswell, 2001). A recent
study demonstrated that females have
substantially higher mortality than
males (Pace et al., 2017), and as a result,
also have substantially shorter life
expectancies.
Gestation is approximately one year,
after which calves typically nurse for
around a year (Kenney, 2009; Kraus et
al., 2007; Lockyer, 1984). After weaning
calves, females typically undergo a
‘resting’ year before becoming pregnant
again, presumably because they need
time to recover from the energy deficit
experienced during lactation (Fortune et
al., 2012, 2013; Pettis et al., 2017b).
From 1983 to 2005, annual average
calving intervals ranged from 3 to 5.8
years (Knowlton et al., 1994; Kraus et
al., 2007). Between 2006 and 2015,
annual average calving intervals
continued to vary within this range, but
in 2016 and 2017 longer calving
intervals were reported (6.3 to 6.6 years
in 2016 and 10.2 years in 2017; Pettis
and Hamilton, 2015, 2016; Pettis et al.,
2017a; Surrey-Marsden et al., 2017;
Hayes et al., 2018b). Females have been
known to give birth as young as five
years old, but the mean age of first
parturition is about 10 years old (Kraus
et al., 2007).
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Pregnant North Atlantic right whales
migrate south, through the mid-Atlantic
region of the United States, to low
latitudes during late fall where they
overwinter and give birth in shallow,
coastal waters (Kenney, 2009; Krzystan
et al., 2018). During spring, these
females migrate back north with their
new calves to high latitude foraging
grounds where they feed on large
concentrations of copepods, primarily
Calanus finmarchicus (NMFS, 2017).
Some non-reproductive North Atlantic
right whales (males, juveniles, nonreproducing females) also migrate south
through the mid-Atlantic region,
although at more variable times
throughout the winter, while others
appear to not migrate south, and instead
remain in the northern feeding grounds
year round or go elsewhere (Bort et al.,
2015; Morano et al., 2012; NMFS, 2017).
Nonetheless, calving females arrive to
the southern calving grounds earlier and
stay in the area more than twice as long
as other demographics (Krzystan et al.,
2018). Little is known about North
Atlantic right whale habitat use in the
mid-Atlantic, but recent acoustic data
indicate near year-round presence of at
least some whales off the coasts of New
Jersey, Virginia, and North Carolina
(Davis et al., 2017; Hodge et al., 2015a;
Salisbury et al., 2016; Whitt et al.,
2013). Oedekoven et al. (2015)
conducted an expert elicitation exercise
to assess potential seasonal abundance
of right whales in the mid-Atlantic,
confirming that very low numbers of
whales should be expected to be present
in the region outside of the November
to April timeframe. While it is generally
not known where North Atlantic right
whales mate, some evidence suggests
that mating may occur in the northern
feeding grounds (Cole et al., 2013;
Matthews et al., 2014).
The western North Atlantic right
whale population demonstrated overall
growth of 2.8 percent per year between
1990 to 2010, despite a decline in 1993
and no growth between 1997 and 2000
(Pace et al., 2017). However, since 2010
the population has been in decline, with
a 99.99 percent probability of a decline
of just under one percent per year (Pace
et al., 2017). Between 1990 and 2015,
survival rates appeared to be relatively
stable, but differed between the sexes,
with males having higher survivorship
than females (males: 0.985 ± 0.0038;
females: 0.968 ± 0.0073) leading to a
male-biased sex ratio (approximately
1.46 males per female; Pace et al., 2017).
During this same period, calving rates
varied substantially, with low calving
rates coinciding with all three periods of
decline or no growth (Pace et al., 2017).
VerDate Sep<11>2014
18:20 Dec 06, 2018
Jkt 247001
On average, North Atlantic right whale
calving rates are estimated to be roughly
half that of southern right whales (E.
australis) (Pace et al., 2017), which are
increasing in abundance (NMFS, 2015c).
While data are not yet available to
statistically estimate the population’s
trend beyond 2015, three lines of
evidence indicate the population is still
in decline. First, calving rates in recent
years were low, with only five new
calves being documented in 2017 (Pettis
et al., 2017a), well below the number
needed to compensate for expected
mortalities (Pace et al., 2017). In 2018,
no new North Atlantic right whale
calves were documented in their calving
grounds; this represented the first time
since annual NOAA aerial surveys
began in 1989 that no new right whale
calves were observed. Long-term
photographic identification data
indicate new calves rarely go
undetected, so these years likely
represent a continuation of the low
calving rates that began in 2012 (Kraus
et al., 2007; Pace et al., 2017). Second,
as noted above, the abundance estimate
for 2016 is 451 individuals, down
approximately 1.5 percent from 458 in
2015. Third, since June 2017, at least 20
North Atlantic right whales have died in
what has been declared an Unusual
Mortality Event (UME; see additional
discussion of the UME below).
Analysis of mtDNA from North
Atlantic right whales has identified
seven mtDNA haplotypes in the western
North Atlantic (Malik et al., 1999;
McLeod and White, 2010). This is
significantly less diverse than southern
right whales and may indicate
inbreeding (Hayes et al., 2018a; Malik et
al., 2000; Schaeff et al., 1997). While
analysis of historic DNA taken from
museum specimens indicates that the
eastern and western populations were
likely not genetically distinct, the lack
of recovery of the eastern North Atlantic
population indicates at least some level
of population segregation (Rosenbaum
et al., 1997, 2000). Overall, the species
has low genetic diversity as would be
expected based on its low abundance.
However, analysis of 16th and 17th
century whaling bones indicate this low
genetic diversity may pre-date whaling
activities (McLeod et al., 2010). Despite
this, Frasier et al. (2013) recently
identified a post-copulatory mechanism
that appears to be slowly increasing
genetic diversity among right whale
calves.
In recent years, there has been a shift
in distribution in right whale feeding
grounds, with fewer animals being seen
in the Great South Channel and the Bay
of Fundy and perhaps more animals
being observed in the Gulf of Saint
PO 00000
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Fmt 4701
Sfmt 4703
63319
Lawrence and mid-Atlantic region
(Daoust et al., 2017; Davis et al., 2017;
Hayes et al., 2018a; Pace et al., 2017;
Meyer-Gutbrod et al., 2018). However,
in recent years, a few known
individuals from the western population
have been seen in the eastern Atlantic,
suggesting some individuals may have
wider ranges than previously thought
(Kenney, 2009).
Currently, no identified right whale
recovery goals have been met (for more
information on these goals, see the 2005
recovery plan; NMFS, 2005, 2017). With
whaling now prohibited, the two major
known human causes of mortality are
vessel strikes and entanglement in
fishing gear (Hayes et al., 2018b). Some
progress has been made in mitigating
vessel strikes by regulating vessel
speeds in certain areas (78 FR 73726;
December 9, 2013) (Conn and Silber,
2013), but entanglement in fishing gear
remains a major threat (Kraus et al.,
2016), which appears to be worsening
(Hayes et al., 2018b). From 1990 to
2010, the population experienced
overall growth consistent with one of its
recovery goals. However, the population
is currently experiencing a UME that
appears to be related to both vessel
strikes and entanglement in fishing gear
(Daoust et al., 2017; see below for
further discussion). In addition, the low
female survival, male biased sex ratio,
and low calving success indicated by
recent modeling are contributing to the
population’s current decline (Pace et al.,
2017). While there are likely a multitude
of factors involved, low calving has
been linked to poor female health
(Rolland et al., 2016) and reduced prey
availability (Meyer-Gutbrod and Greene,
2014, 2017; Meyer-Gutbrod et al., 2018).
Furthermore, entanglement in fishing
gear appears to have substantial health
and energetic costs that affect both
survival and reproduction (Pettis et al.,
2017b; Robbins et al., 2015; Rolland et
al., 2017; van der Hoop et al., 2017;
Hayes et al., 2018b; Hunt et al., 2018;
Lysiak et al., 2018). In fact, there is
evidence of a population-wide decline
in health since the early 1990s, the last
time the population experienced a
population decline (Rolland et al.,
2016). Given this status, the species
resilience to future perturbations is
considered very low (Hayes et al.,
2018b). Using a matrix population
projection model, Hayes et al. (2018b)
estimate that by 2029 the population
will to decline to the 1990 estimate of
123 females if the current rate of decline
is not altered. Consistent with this,
recent modelling efforts by MeyerGutbrod and Greene (2017) indicate that
that the species may decline towards
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Federal Register / Vol. 83, No. 235 / Friday, December 7, 2018 / Notices
extinction if prey conditions worsen, as
predicted under future climate
scenarios, and anthropogenic mortalities
are not reduced (Grieve et al., 2017;
Meyer-Gutbrod et al., 2018). In fact,
recent data from the Gulf of Maine and
Gulf of St. Lawrence indicate prey
densities may already be in decline
(Devine et al., 2017; Johnson et al.,
2013; Meyer-Gutbrod et al., 2018).
Discussion of Abundance Estimates—
In Table 2 above, we report two sets of
abundance estimates: Those from
NMFS’s SARs and those predicted by
Roberts et al. (2016)—for the latter we
provide both the annual mean and
maximum, for those taxa for which
monthly predictions are available (i.e.,
all taxa for which density surface
models, versus stratified models, were
produced). Please see Table 2, footnotes
2–3 for more detail. We provided a
relatively brief discussion of available
abundance estimates in the Notice of
Proposed IHAs, stating that the Roberts
et al. (2016) abundance predictions are
generally the most appropriate in this
case for purposes of comparison with
estimated exposures (see ‘‘Estimated
Take’’). This is because the outputs of
these models were used in most cases to
generate the exposure estimates, i.e., we
appropriately make relative
comparisons between the exposures
predicted by the outputs of the model
and the abundance predicted by the
model. Following review of public
comments received and additional
review of available information
regarding abundance estimates, we
provide revised and additional
discussion of available abundance
estimates and our use of these herein.
Because both the SAR (in most cases)
and Roberts et al. (2016) values provide
estimates of abundance only within the
U.S. EEZ, whereas the specified
activities (and associated exposure
estimates) extend beyond this region out
to 350 nmi, we calculated the expected
abundance of each species in the region
offshore of the EEZ out to 350 nmi.
These values, reported in Table 2, are
appropriately added to the Roberts et al.
(2016) EEZ estimates to provide the total
model-predicted abundance. Please see
footnote 4 for more detail. Our prior use
of abundance estimates that ignore the
assumed abundance of animals outside
the EEZ (explicit in the exposure
estimation process) was an error that is
rectified here.
As was described in our Notice of
Proposed IHAs, NMFS’s SAR
abundance estimates are typically
generated from the most recent
shipboard and/or aerial surveys
conducted, and often incorporate
correction for detection bias. While
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18:20 Dec 06, 2018
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these snapshot estimates provide
valuable information about a stock, they
are not generally relevant here for use in
comparison to the take estimates, as
stated above. The Roberts et al. (2016)
abundance estimates represent the
output of predictive models derived
from observations and associated
environmental parameters and are in
fact based on substantially more data
than are NMFS’s SAR abundance
estimates—thus minimizing the
influence of interannual variability on
abundance estimates. For example,
NMFS’s pilot whale abundance
estimates from surveys conducted in
2004 and 2011 differed by 21 percent—
a change not expected to represent the
actual change in abundance—indicating
that it may be more appropriate to use
a model prediction that incorporates all
available data.
The abundance values reported by
Roberts et al. (2016), and which we
largely used in our analyses in the
Notice of Proposed IHAs, are mean
annual abundance estimates (for species
for which data are sufficient to model
seasonality; for other species only a
stratified model with static abundance
could be produced). However, for those
species for which seasonal variability
could be modeled (via density surface
models), abundance estimates are
produced for each month (monthly
maps of species distribution and
associated abundance values are
provided in supplementary reports for
each taxon; these are available online at:
seamap.env.duke.edu/models/Duke-ECGOM-2015/). Following review of public
comments received, we determined it
appropriate to use the most appropriate
maximum abundance estimate for
purposes of comparison with the
exposure estimate, rather than the mean.
While it is appropriate to use a mean
density value in estimating potential
exposures over a year in order to avoid
over- or under-estimation, the best
actual population estimate for
comparison would be the maximum
theoretical population. That is, exposure
estimates are most appropriately
generated through use of means
precisely because densities are expected
to fluctuate within a study area
throughout the year; however, because
these fluctuations do not represent
actual changes in population size, the
maximum predicted abundance should
be used in comparison with a given
exposure estimate.
The appropriate maximum estimate
for each taxon more closely represents
actual total theoretical abundance of the
stock as a whole, as those animals may
exit the study area during other months
but still exist conceptually as members
PO 00000
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Fmt 4701
Sfmt 4703
of the population. The mean does not
represent the actual population
abundance, because although there are
seasonal shifts in distribution, the actual
population abundance should be as
estimated for the period when the
largest portion of the population is
present in the area. While species may
migrate or shift distribution out of the
study area, total abundance of a stock
changes only via births and deaths, i.e.,
there is only one true abundance of the
species. We note that for some taxa,
Roberts et al. express confidence in the
monthly model outputs, e.g., where the
predicted seasonal variations in
abundance match those reported in the
literature. However, for others they do
not, e.g., where there is little
information available in the literature to
corroborate the predicted seasonal
variation. Lack of corroboration in the
latter example would be a valid reason
for not relying on monthly model
outputs when determining the timing or
location of a specific project. However,
this does not impact our determination
that the maximum theoretical
population abundance is appropriate to
use for purposes of comparison. For
those taxa for which the monthly
predictions are recommended for use,
we use the maximum monthly
prediction. For the remaining taxa for
which a density surface model could be
produced, we believe that use of the
maximum monthly prediction may also
be warranted. However, because for
some of these species there are
substantial month-to-month fluctuations
and a corresponding lack of data in the
literature regarding seasonal
distribution, we use the maximum mean
seasonal (i.e., three-month) abundance
prediction for purposes of comparison
as a precaution.
For most species, we use the Roberts
et al. (2016) abundance estimate, but
substitute the appropriate maximum
estimate for the mean annual estimate.
Where we deviate from this practice,
e.g., because another available
abundance estimate provides more
complete coverage of the stock’s range,
we provide additional discussion below.
We also note that, regarding SAR
abundance estimates, Waring et al.
(2015) state that the population of sperm
whales found within the eastern U.S.
Atlantic EEZ likely represent only a
fraction of the total stock, indicating
that the abundance associated with
animals found in the EEZ—whether the
SAR abundance or the model-predicted
abundance—likely underestimate the
true abundance of the relevant
population. Additionally, the majority
of current NMFS SAR estimates—those
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based on 2011 NOAA survey effort—do
not account for availability bias due to
submerged animals, so these abundance
estimates are likely biased low.
NMFS’s abundance estimate for the
North Atlantic right whale is based on
models of the sighting histories of
individual whales identified using
photo-identification techniques. North
Atlantic right whales represent one of
the most intensely studied populations
of cetaceans in the world with effort
supported by a rigorously maintained
individual sightings database and
considerable survey effort throughout
their range; therefore, the most
appropriate abundance estimate is based
on this photo-identification database.
The current estimate of 451 individuals
(95% credible intervals 434–464)
reflects the database as of November
2017 (www.fisheries.noaa.gov/national/
marine-mammal-protection/draftmarine-mammal-stock-assessmentreports).
The 2007 Canadian Trans-North
Atlantic Sighting Survey (TNASS),
which provided full coverage of the
Atlantic Canadian coast (Lawson and
Gosselin, 2009), provided abundance
estimates for multiple stocks. The
abundance estimates from this survey
were corrected for perception and
availability bias, when possible. In
general, where the TNASS survey effort
provided superior coverage of a stock’s
range (as compared with NOAA survey
effort), we elect to use the resulting
abundance estimate over either the
current NMFS abundance estimate
(derived from survey effort with inferior
coverage of the stock range) or the
Roberts et al. (2016) predictions (which
are based on survey data from within
U.S. waters). The TNASS data were not
made available to the model authors
(Roberts et al., 2015a).
We use the TNASS abundance
estimate for the minke whale and for the
short-beaked common dolphin. While
the TNASS survey also produced an
abundance estimate of 3,522 (CV=0.27)
fin whales, and similarly better
represents the stock range than does
NMFS’s SAR estimate, this value
underrepresents the maximum
population predicted by Roberts et al.
(2016). We also note that, while there
appears to be some slight overlap in
their coverage of stock ranges, the
abundance estimates provided by the
TNASS surveys and by NMFS’s SAR
estimates largely cover separate portions
of the ranges. The TNASS effort
involved aerial surveys covering the
Labrador Shelf and Grand Banks, the
Gulf of St. Lawrence, and the Scotian
Shelf, and the abundance estimates also
included the results of aerial surveys
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conducted by NOAA in the Bay of
Fundy. NMFS’s current SAR estimates
reflect NOAA shipboard and aerial
survey effort conducted from Florida to
the lower Bay of Fundy. Therefore, the
most appropriate abundance estimate
for these stocks may be a combination
of the abundance estimates (for common
dolphin: 70,184 (SAR) + 173,486
(TNASS) = 243,670; for minke whale:
2,591 (SAR) + 20,741 (TNASS) =
23,332). Other abundance estimates that
may cover additional portions of these
stocks’ ranges are described in Waring et
al. (2013). However, we use only the
TNASS estimates, which better cover
the stock ranges, because we are
uncertain about the degree of potential
coverage overlap in Canadian waters.
Note that, while the same TNASS
survey produced an abundance estimate
of 2,612 (CV=0.26) humpback whales,
the survey did not provide superior
coverage of the stock’s range in the same
way that it did for minke whales
(Waring et al., 2016; Lawson and
Gosselin, 2011). In addition, based on
photo-identification only 39 percent of
individual humpback whales observed
along the mid- and south Atlantic U.S.
coast are from the Gulf of Maine stock
(Barco et al., 2002). Therefore, we use
the Roberts et al. (2016) prediction for
humpback whales. We note that the
Roberts et al. (2016) maximum estimate
of 1,994 humpback whales likely
underrepresents the relevant
population, i.e., the West Indies
breeding population. Bettridge et al.
(2003) estimated the size of this
population at 12,312 (95% CI 8,688–
15,954) whales in 2004–05, which is
consistent with previous population
estimates of approximately 10,000–
11,000 whales (Stevick et al., 2003;
Smith et al., 1999) and the increasing
trend for the West Indies DPS (Bettridge
et al., 2015). However, we retain the
value predicted by Roberts et al. (2016)
for appropriate comparison with the
number of exposures predicted in the
U.S. EEZ.
The current SARs abundance estimate
for Kogia spp. is substantially higher
than that provided by Roberts et al.
(2016). However, the data from which
the SARs estimate is derived was not
made available to Roberts et al. (Roberts
et al., 2015h), and those more recent
surveys reported observing substantially
greater numbers of Kogia spp. than did
earlier surveys (43 sightings, more than
the combined total of 31 reported from
all surveys from 1992–2014 considered
by Roberts et al. (2016)) (NMFS, 2011).
A 2013 NOAA survey, also not available
to the model authors, reported 68
sightings of Kogia spp. (NMFS, 2013a).
In addition, the SARs report an increase
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in Kogia spp. strandings (92 from 2001–
05; 187 from 2007–11) (Waring et al.,
2007; 2013). A simultaneous increase in
at-sea observations and strandings
suggests increased abundance of Kogia
spp., though NMFS has not conducted
any trend analysis (Waring et al., 2013).
Therefore, we believe the most
appropriate abundance estimate for use
here is that currently reported by NMFS
in the SARs. In fact, Waring et al. (2013)
suggest that because this estimate was
corrected for perception bias but not
availability bias, the true estimate could
be two to four times larger.
Biologically Important Areas—Several
biologically important areas for some
marine mammal species are recognized
in the survey areas in the mid- and
south Atlantic. Critical habitat is
designated for the North Atlantic right
whale within the southeast United
States (81 FR 4838; January 27, 2016).
Critical habitat is defined by section 3
of the ESA as (1) the specific areas
within the geographical area occupied
by the species, at the time it is listed,
on which are found those physical or
biological features (a) essential to the
conservation of the species and (b)
which may require special management
considerations or protection; and (2)
specific areas outside the geographical
area occupied by the species at the time
it is listed, upon a determination by the
Secretary that such areas are essential
for the conservation of the species.
Critical habitat for the right whale in the
southeast United States (i.e., Unit 2)
encompasses calving habitat and is
designated on the basis of the following
essential features: (1) Calm sea surface
conditions of Force 4 or less on the
Beaufort Wind Scale; (2) sea surface
temperatures from a minimum of 7° C,
and never more than 17° C; and (3)
water depths of 6 to 28 m, where these
features simultaneously co-occur over
contiguous areas of at least 231 nmi2 of
ocean waters during the months of
November through April. When these
features are available, they are selected
by right whale cows and calves in
dynamic combinations that are suitable
for calving, nursing, and rearing, and
which vary, within the ranges specified,
depending on factors such as weather
and age of the calves.
The area associated with such features
includes nearshore and offshore waters
of the southeastern United States,
extending from Cape Fear, North
Carolina south to 28° N. The specific
area designated as Unit 2 of critical
habitat, as defined by regulation (81 FR
4838; January 27, 2016), is demarcated
by rhumb lines connecting the specific
points identified in 50 CFR
226.203(b)(2), as shown in Figure 2.
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There is no critical habitat designated
for any other species within the survey
area.
Figure 2. North Atlantic Right Whale Critical Habitat, Southeast United States.
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Biologically important areas for North
Atlantic right whales in the mid- and
south Atlantic were further described by
LaBrecque et al. (2015). The authors
describe an area of importance for
reproduction that somewhat expands
the boundaries of the critical habitat
designation, including waters out to the
25-m isobath from Cape Canaveral to
Cape Lookout from mid-November to
mid-April, on the basis of habitat
analyses (Good, 2008; Keller et al.,
2012) and sightings data (e.g., Keller et
al., 2006; Schulte and Taylor, 2012)
indicating that sea surface temperatures
between 13° to 15° C and water depths
between 10–20 m are critical parameters
for calving. Right whales leave northern
feeding grounds in November and
December to migrate along the
continental shelf to the calving grounds
or to unknown winter areas before
returning to northern areas by late
spring. Right whales are known to travel
along the continental shelf, but it is
unknown whether they use the entire
shelf area or are restricted to nearshore
waters (Schick et al., 2009; Whitt et al.,
2013). LaBrecque et al. (2015) define an
important area for migratory behavior
on the basis of aerial and vessel-based
survey data, photo-identification data,
radio-tracking data, and expert
judgment.
As noted by LaBrecque et al. (2015),
additional cetacean species are known
to have strong links to bathymetric
features, although there is currently
insufficient information to specifically
identify these areas. For example, pilot
whales and Risso’s dolphins aggregate at
the shelf break in the survey area. These
and other locations predicted as areas of
high abundance (Roberts et al., 2016)
form the basis of spatiotemporal
restrictions on survey effort as described
under ‘‘Mitigation.’’ In addition, other
data indicate potential areas of
importance that are not yet fully
described. Risch et al. (2014) describe
minke whale presence offshore of the
shelf break (evidenced by passive
acoustic recorders), which may be
indicative of a migratory area, while
other data provides evidence that sei
whales aggregate near meandering
frontal eddies over the continental shelf
in the Mid-Atlantic Bight (Newhall et
al., 2012).
Unusual Mortality Events (UME)—A
UME is defined under the MMPA as ‘‘a
stranding that is unexpected; involves a
significant die-off of any marine
mammal population; and demands
immediate response.’’ From 1991 to the
present, there have been approximately
twelve formally recognized UMEs
affecting marine mammals in the survey
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area and involving species under
NMFS’s jurisdiction. A recently ended
UME involved bottlenose dolphins.
Three UMEs are ongoing and under
investigation. These involve humpback
whales, North Atlantic right whales, and
minke whales. Specific information for
each ongoing UME is provided below.
There is currently no direct connection
between the three UMEs, as there is no
evident cause of stranding or death that
is common across the three species
involved in the different UMEs.
Additionally, strandings across the three
species are not clustering in space or
time.
Since January 2016, elevated
humpback whale mortalities have
occurred along the Atlantic coast from
Maine through Florida (though there are
only two records to date south of North
Carolina). As of October 2018, partial or
full necropsy examinations have been
conducted on approximately half of the
84 known cases. Of the cases examined,
approximately half had evidence of
human interaction (ship strike or
entanglement). Some of these
investigated mortalities showed blunt
force trauma or pre-mortem propeller
wounds indicative of vessel strike,
indicating a strike rate above the annual
long-term average; however, these
findings of pre-mortem vessel strike are
not consistent across all of the whales
examined and more research is needed.
NOAA is consulting with researchers
that are conducting studies on the
humpback whale populations, and these
efforts may provide information on
changes in whale distribution and
habitat use that could provide
additional insight into how these vessel
interactions occurred. Three previous
UMEs involving humpback whales have
occurred since 2000, in 2003, 2005, and
2006. More information is available at
www.fisheries.noaa.gov/national/
marine-life-distress/2016-2018humpback-whale-unusual-mortalityevent-along-atlantic-coast (accessed
October 17, 2018).
Since January 2017, elevated minke
whale strandings have occurred along
the Atlantic coast from Maine through
South Carolina, with highest numbers in
Massachusetts, Maine, and New York.
As of October 2018, partial or full
necropsy examinations have been
conducted on more than 60 percent of
the 54 known cases. Preliminary
findings in several of the whales have
shown evidence of human interactions
or infectious disease. These findings are
not consistent across all of the whales
examined, so more research is needed.
As part of the UME investigation
process, NOAA is assembling an
independent team of scientists to
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coordinate with the Working Group on
Marine Mammal Unusual Mortality
Events to review the data collected,
sample stranded whales, and determine
the next steps for the investigation.
More information is available at:
www.fisheries.noaa.gov/national/
marine-life-distress/2017-2018-minkewhale-unusual-mortality-event-alongatlantic-coast (accessed October 17,
2018).
Elevated North Atlantic right whale
mortalities began in June 2017,
primarily in Canada. To date, there are
a total of 20 confirmed dead stranded
whales (12 in Canada; 8 in the United
States), and 5 live whale entanglements
in Canada have been documented. Full
necropsy examinations have been
conducted on 13 of the cases, with
results currently available for seven of
these that occurred in Canada (Daoust et
al., 2017). Results indicate that two
whales died from entanglement in
fishing gear and, for four whales,
necropsy findings were compatible with
acute death due to trauma (although it
is uncertain whether they were struck
pre- or post-mortem) (Daoust et al.,
2017). Several investigated cases are
undetermined due to advanced
decomposition. Overall, findings to date
confirm that vessel strikes and fishing
gear entanglement continue to be the
key threats to recovery of North Atlantic
right whales. In response, the Canadian
government has enacted fishery closures
to help reduce future entanglements and
has modified fixed gear fisheries, as
well as implementing temporary
mandatory vessel speed restrictions in a
portion of the Gulf of St. Lawrence.
NOAA is cooperating with Canadian
government officials as they investigate
the incidents in Canadian waters. A
previous UME involving right whales
occurred in 1996. More information is
available at: www.fisheries.noaa.gov/
national/marine-life-distress/2017-2018north-atlantic-right-whale-unusualmortality-event (accessed October 17,
2018).
Beginning in July 2013, elevated
strandings of bottlenose dolphins were
observed along the Atlantic coast from
New York to Florida. The investigation
was closed in 2015, with the UME
ultimately being attributed to cetacean
morbillivirus (though additional
contributory factors are under
investigation; www.fisheries.noaa.gov/
national/marine-life-distress/2013-2015bottlenose-dolphin-unusual-mortalityevent-mid-atlantic; accessed July 2,
2018). Dolphin strandings during 2013–
15 were greater than six times higher
than the annual average from 2007–12,
with the most strandings reported from
Virginia, North Carolina, and Florida. A
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total of approximately 1,650 bottlenose
dolphins stranded from June 2013 to
March 2015 and, additionally, a small
number of individuals of several other
cetacean species stranded during the
UME and tested positive for
morbillivirus (humpback whale, fin
whale, minke whale, pygmy sperm
whale, and striped dolphin). Only one
offshore ecotype dolphin has been
identified, meaning that over 99 percent
of affected dolphins were of the coastal
ecotype (D. Fauquier; pers. comm.).
Research, to include analyses of
stranding samples and post-UME
monitoring and modeling of surviving
populations, will continue in order to
better understand the impacts of the
UME on the affected stocks. Notably, an
earlier major UME in 1987–88 was also
caused by morbillivirus. Over 740
stranded dolphins were recovered
during that event.
Additional recent UMEs include
various localized events with
undetermined cause involving
bottlenose dolphins (e.g., South
Carolina in 2011; Virginia in 2009) and
an event affecting common dolphins
and Atlantic white-sided dolphins from
North Carolina to New Jersey (2008;
undetermined). For more information
on UMEs, please visit:
www.fisheries.noaa.gov/national/
marine-life-distress/marine-mammalunusual-mortality-events.
Take Reduction Planning—Take
reduction plans are designed to help
recover and prevent the depletion of
strategic marine mammal stocks that
interact with certain U.S. commercial
fisheries, as required by Section 118 of
the MMPA. The immediate goal of a
take reduction plan is to reduce, within
six months of its implementation, the
mortality and serious injury of marine
mammals incidental to commercial
fishing to less than the potential
biological removal level. The long-term
goal is to reduce, within five years of its
implementation, the mortality and
serious injury of marine mammals
incidental to commercial fishing to
insignificant levels, approaching a zero
serious injury and mortality rate, taking
into account the economics of the
fishery, the availability of existing
technology, and existing state or
regional fishery management plans.
Take reduction teams are convened to
develop these plans.
There are several take reduction plans
in place for marine mammals in the
survey areas of the mid- and south
Atlantic. We described these here
briefly in order to fully describe, in
conjunction with referenced material,
the baseline conditions for the affected
marine mammal stocks. The Atlantic
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Large Whale Take Reduction Plan
(ALWTRP) was implemented in 1997 to
reduce injuries and deaths of large
whales due to incidental entanglement
in fishing gear. The ALWTRP is an
evolving plan that changes as NMFS
learns more about why whales become
entangled and how fishing practices
might be modified to reduce the risk of
entanglement. It has several
components, including restrictions on
where and how gear can be set and
requirements for entangling gears (i.e.,
trap/pot and gillnet gears). The
ALWTRP addresses those species most
affected by fishing gear entanglements,
i.e., North Atlantic right whale,
humpback whale, fin whale, and minke
whale. Annual human-caused mortality
exceeds PBR for the North Atlantic right
whale and certain other ESA-listed
whale species. More information is
available online at:
www.greateratlantic.fisheries.noaa.gov/
protected/whaletrp/.
NMFS implemented a Harbor
Porpoise Take Reduction Plan (HPTRP)
to reduce interactions between harbor
porpoise and commercial gillnet gear in
both New England and the mid-Atlantic.
The HPTRP has several components
including restrictions on where, when,
and how gear can be set, and in some
areas requires the use of acoustic
deterrent devices. More information is
available online at:
www.greateratlantic.fisheries.noaa.gov/
protected/porptrp/.
The Atlantic Trawl Gear Take
Reduction Team was developed to
address the incidental mortality and
serious injury of pilot whales, common
dolphins, and white-sided dolphins
incidental to Atlantic trawl fisheries.
More information is available online at:
www.greateratlantic.fisheries.noaa.gov/
Protected/mmp/atgtrp/. Separately,
NMFS established a Pelagic Longline
Take Reduction Plan (PLTRP) to address
the incidental mortality and serious
injury of pilot whales in the midAtlantic region of the Atlantic pelagic
longline fishery. The PLTRP includes a
special research area, gear
modifications, outreach material,
observer coverage, and captains’
communications. Pilot whales incur
substantial incidental mortality and
serious injury due to commercial
fishing, and therefore are of particular
concern. More information is available
online at: www.nmfs.noaa.gov/pr/
interactions/trt/pl-trt.html.
Marine Mammal Hearing
Hearing is the most important sensory
modality for marine mammals
underwater, and exposure to
anthropogenic sound can have
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deleterious effects. To appropriately
assess the potential effects of exposure
to sound, it is necessary to understand
the frequency ranges marine mammals
are able to hear. Current data indicate
that not all marine mammal species
have equal hearing capabilities (e.g.,
Richardson et al., 1995; Wartzok and
Ketten, 1999; Au and Hastings, 2008).
To reflect this, Southall et al. (2007)
recommended that marine mammals be
divided into functional hearing groups
based on directly measured or estimated
hearing ranges on the basis of available
behavioral response data, audiograms
derived using auditory evoked potential
techniques, anatomical modeling, and
other data. Note that no direct
measurements of hearing ability have
been successfully completed for
mysticetes (i.e., low-frequency
cetaceans). NMFS (2018) describes
generalized hearing ranges for these
marine mammal hearing groups.
Generalized hearing ranges were chosen
based on the approximately 65 dB
threshold from the normalized
composite audiograms, with the
exception for lower limits for lowfrequency cetaceans where the lower
bound was deemed to be biologically
implausible and the lower bound from
Southall et al. (2007) retained. Pinniped
functional hearing is not discussed here,
as no pinnipeds are expected to be
affected by the specified activity. The
functional groups and the associated
frequencies are indicated below (note
that these frequency ranges correspond
to the range for the composite group,
with the entire range not necessarily
reflecting the capabilities of every
species within that group):
• Low-frequency cetaceans
(mysticetes): Generalized hearing is
estimated to occur between
approximately 7 Hz and 35 kHz;
• Mid-frequency cetaceans (larger
toothed whales, beaked whales, and
most delphinids): Generalized hearing is
estimated to occur between
approximately 150 Hz and 160 kHz;
• High-frequency cetaceans
(porpoises, river dolphins, and members
of the genera Kogia and
Cephalorhynchus; including two
members of the genus Lagenorhynchus,
on the basis of recent echolocation data
and genetic data): Generalized hearing is
estimated to occur between
approximately 275 Hz and 160 kHz.
For more detail concerning these
groups and associated frequency ranges,
please see NMFS (2018) for a review of
available information. Thirty-four
marine mammal species, all cetaceans,
have the reasonable potential to cooccur with the survey activities. Please
refer to Table 2. Of the species that may
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be present, seven are classified as lowfrequency cetaceans (i.e., all mysticete
species), 24 are classified as midfrequency cetaceans (i.e., all delphinid
and ziphiid species and the sperm
whale), and three are classified as highfrequency cetaceans (i.e., harbor
porpoise and Kogia spp.).
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Potential Effects of the Specified
Activities on Marine Mammals and
Their Habitat
In our Notice of Proposed IHAs, this
section included a comprehensive
summary and discussion of the ways
that components of the specified
activity may impact marine mammals
and their habitat, including general
background information on sound and
specific discussion of potential effects to
marine mammals from noise produced
through use of airgun arrays. We do not
repeat that discussion here, instead
referring the reader to the Notice of
Proposed IHAs. However, we do
provide a more thorough discussion
regarding potential impacts to marine
mammal habitat via effects to prey
species, as well as discussion of
important new information regarding
potential impacts to prey species
produced since publication of our
notice. The ‘‘Estimated Take’’ section
later in this document includes a
quantitative analysis of the number of
individuals that are expected to be taken
by this activity. The ‘‘Negligible Impact
Analyses and Determinations’’ section
will include an analysis of how these
specific activities will impact marine
mammals and will consider the content
of this section, the ‘‘Estimated Take’’
section, and the ‘‘Mitigation’’ section, to
draw conclusions regarding the likely
impacts of these activities on the
reproductive success or survivorship of
individuals and from that on the
affected marine mammal populations.
Description of Active Acoustic Sound
Sources
In our Notice of Proposed IHAs, this
section contained a brief technical
background on sound, the
characteristics of certain sound types,
and on metrics used in the proposal
inasmuch as the information is relevant
to the specified activity and to a
discussion of the potential effects of the
specified activity on marine mammals
found later in this document. Here, we
summarize key information relating to
terminology used in this notice.
Amplitude (or ‘‘loudness’’) of sound
is typically described using the relative
unit of the decibel (dB). A sound
pressure level (SPL) in dB is described
as the ratio between a measured
pressure and a reference pressure (for
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underwater sound, this is 1 microPascal
(mPa)). The source level (SL) represents
the SPL referenced at a distance of 1 m
from the source (referenced to 1 mPa),
while the received level is the SPL at
the listener’s position (referenced to 1
mPa).
Root mean square (rms) is the
quadratic mean sound pressure over the
duration of an impulse. This
measurement is often used in the
context of discussing behavioral effects,
in part because behavioral effects,
which often result from auditory cues,
may be better expressed through
averaged units than by peak pressures.
Sound exposure level (SEL; represented
as dB re 1 mPa2–s) represents the total
energy contained within a pulse, and
considers both intensity and duration of
exposure. Peak sound pressure (also
referred to as zero-to-peak sound
pressure or 0–p) is the maximum
instantaneous sound pressure
measurable in the water at a specified
distance from the source, and is
represented in the same units as the rms
sound pressure. Another common
metric is peak-to-peak sound pressure
(pk–pk), which is the algebraic
difference between the peak positive
and peak negative sound pressures.
Peak-to-peak pressure is typically
approximately 6 dB higher than peak
pressure (Southall et al., 2007).
As described in more detail in our
Notice of Proposed IHAs, airgun arrays
are in a general sense considered to be
omnidirectional sources of pulsed noise.
Pulsed sound sources (as compared
with non-pulsed sources) produce
signals that are brief (typically
considered to be less than one second),
broadband, atonal transients (ANSI,
1986, 2005; Harris, 1998; NIOSH, 1998;
ISO, 2003) and occur either as isolated
events or repeated in some succession.
Pulsed sounds are all characterized by
a relatively rapid rise from ambient
pressure to a maximal pressure value
followed by a rapid decay period that
may include a period of diminishing,
oscillating maximal and minimal
pressures, and generally have an
increased capacity to induce physical
injury as compared with sounds that
lack these features. Airguns produce
sound with energy in a frequency range
from about 10–2,000 Hz, with most
energy radiated at frequencies below
200 Hz. Although the amplitude of the
acoustic wave emitted from the source
is equal in all directions (i.e.,
omnidirectional), airgun arrays do
possess some directionality due to
different phase delays between guns in
different directions. Airgun arrays are
typically tuned to maximize
functionality for data acquisition
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purposes, meaning that sound
transmitted in horizontal directions and
at higher frequencies is minimized to
the extent possible.
Anticipated Effects on Marine Mammal
Habitat
We received numerous public
comments regarding potential effects to
marine mammal habitat, including to
prey species, including some comments
pointing out additional relevant
literature and/or claiming that we had
not adequately considered potential
impacts to prey species. While we
disagree that we had not adequately
considered potential impacts to marine
mammal habitat, particularly with
regard to marine mammal prey, in
response to public comment we did
consider additional literature regarding
potential impacts to prey species, as
well as some new literature made
available since publication of our Notice
of Proposed IHAs (e.g., McCauley et al.,
2017). Portions of this information were
described in responses to comments
above. We provide a revised summary of
our review of available literature
regarding impacts to prey species here
(please see our Notice of Proposed IHAs
for our discussions of potential effects to
other aspects of marine mammal habitat,
including acoustic habitat). Our overall
conclusions regarding potential impacts
of the specified activities on marine
mammal habitat are unchanged. As
stated in our Notice of Proposed IHAs,
our review of the available information
and the specific nature of the activities
considered herein suggest that the
activities associated with the planned
actions are not likely to have more than
short-term adverse effects on any prey
habitat or populations of prey species or
on the quality of acoustic habitat.
Further, any impacts to marine mammal
habitat are not expected to result in
significant or long-term consequences
for individual marine mammals, or to
contribute to adverse impacts on their
populations. Information supporting
this conclusion is summarized below.
Effects to Prey—As stated above, here
we provide an updated and more
detailed discussion of the available
information regarding potential effects
to prey, as well as additional support for
our conclusion.
Sound may affect marine mammals
through impacts on the abundance,
behavior, or distribution of prey species
(e.g., crustaceans, cephalopods, fish,
zooplankton). Marine mammal prey
varies by species, season, and location
and, for some, is not well documented.
Here, we describe studies regarding the
effects of noise on known marine
mammal prey.
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Fish utilize the soundscape (see our
Notice of Proposed IHAs for discussion
of this concept) and components of
sound in their environment to perform
important functions such as foraging,
predator avoidance, mating, and
spawning (e.g., Zelick et al., 1999; Fay,
2009). Depending on their hearing
anatomy and peripheral sensory
structures, which vary among species,
fishes hear sounds using pressure and
particle motion sensitivity capabilities
and detect the motion of surrounding
water (Fay et al., 2008). The potential
effects of airgun noise on fishes depends
on the overlapping frequency range,
distance from the sound source, water
depth of exposure, and species-specific
hearing sensitivity, anatomy, and
physiology. Key impacts to fishes may
include behavioral responses, hearing
damage, barotrauma (pressure-related
injuries), and mortality.
Fish react to sounds which are
especially strong and/or intermittent
low-frequency sounds, and behavioral
responses such as flight or avoidance
are the most likely effects. Short
duration, sharp sounds can cause overt
or subtle changes in fish behavior and
local distribution. The reaction of fish to
airguns depends on the physiological
state of the fish, past exposures,
motivation (e.g., feeding, spawning,
migration), and other environmental
factors. Hastings and Popper (2005)
identified several studies that suggest
fish may relocate to avoid certain areas
of sound energy. Several studies have
demonstrated that airgun sounds might
affect the distribution and behavior of
some fishes, potentially impacting
foraging opportunities or increasing
energetic costs (e.g., Fewtrell and
McCauley, 2012; Pearson et al., 1992;
Skalski et al., 1992; Santulli et al.,
1999). One recent study found a 78
percent decline in snapper-grouper
complex species abundance during
evening hours at a reef habitat site off
central North Carolina following an
airgun survey (Paxton et al., 2017).
During the days prior to the survey
passing, fish use of this habitat was
highest during the same hours.
However, our review shows that the
bulk of studies indicate no or slight
reaction to noise (e.g., Miller and
Cripps, 2013; Dalen and Knutsen, 1987;
Pena et al., 2013; Chapman and
Hawkins, 1969; Wardle et al., 2001; Sara
et al., 2007; Jorgenson and Gyselman,
2009; Blaxter et al., 1981; Cott et al.,
2012; Boeger et al., 2006), and that, most
commonly, while there are likely to be
impacts to fish as a result of noise from
nearby airguns, such effects will be
temporary. For example, investigators
reported significant, short-term declines
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in commercial fishing catch rate of
gadid fishes during and for up to five
days after seismic survey operations, but
the catch rate subsequently returned to
normal (Engas et al., 1996; Engas and
Lokkeborg, 2002); other studies have
reported similar findings (Hassel et al.,
2004). Skalski et al. (1992) also found a
reduction in catch rates—for rockfish
(Sebastes spp.) in response to controlled
airgun exposure—but suggested that the
mechanism underlying the decline was
not dispersal but rather decreased
responsiveness to baited hooks
associated with an alarm behavioral
response. A companion study showed
that alarm and startle responses were
not sustained following the removal of
the sound source (Pearson et al., 1992);
therefore, Skalski et al. (1992) suggested
that the effects on fish abundance may
be transitory, primarily occurring during
the sound exposure itself. In some cases,
effects on catch rates are variable within
a study, which may be more broadly
representative of temporary
displacement of fish in response to
airgun noise (i.e., catch rates may
increase in some locations and decrease
in others) than any long-term damage to
the fish themselves (Streever et al.,
2016).
While the findings of Paxton et al.
(2017) may be interpreted as a
significant shift in distribution that
could compromise life history
behaviors—as some commenters have
done—we interpret these findings as
corroborating prior studies indicating
that typically a startle response or shortterm displacement should be expected.
In fact, the evening hours during which
the decline in fish habitat use were
recorded (via video recording) occurred
on the same day that the airgun survey
passed, and no subsequent data is
presented to support an inference that
the response was long-lasting.
Additionally, given that the finding is
based on video images, the lack of
recorded fish presence does not support
a conclusion that the fish actually
moved away from the site or suffered
any serious impairment. Other studies
have been inconclusive regarding the
abundance effects of airgun noise
(Thomson et al., 2014).
SPLs of sufficient strength have been
known to cause injury to fish and fish
mortality and, in some studies, fish
auditory systems have been damaged by
airgun noise (McCauley et al., 2003;
Popper et al., 2005; Song et al., 2008).
(No mortality occurred to fish in any of
these studies.) While experiencing a
TTS, fish may be more susceptible to
fitness impacts resulting from effects to
communication, predator/prey
detection, etc. (Popper et al., 2014).
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However, in most fish species, hair cells
in the ear continuously regenerate and
loss of auditory function likely is
restored when damaged cells are
replaced with new cells (Smith, 2016).
Halvorsen et al. (2012a) showed that a
TTS of 4–6 dB was recoverable within
24 hours for one species. Impacts would
be most severe when the individual fish
is close to the source and when the
duration of exposure is long—neither
condition should be expected in relation
to the specified activities.
Injury caused by barotrauma can
range from slight to severe and can
cause death, and is most likely for fish
with swim bladders. Barotrauma
injuries have been documented during
controlled exposure to impact pile
driving (an impulsive noise source, as
are airguns) (Halvorsen et al., 2012b;
Casper et al., 2013). For geophysical
surveys, the sound source is constantly
moving, and most fish would likely
avoid the sound source prior to
receiving sound of sufficient intensity to
cause physiological or anatomical
damage.
Invertebrates appear to be able to
detect sounds (Pumphrey, 1950; Frings
and Frings, 1967) and are most sensitive
to low-frequency sounds (Packard et al.,
1990; Budelmann and Williamson,
1994; Lovell et al., 2005; Mooney et al.,
2010). Available data suggest that
cephalopods are capable of sensing the
particle motion of sounds and detect
low frequencies up to 1–1.5 kHz,
depending on the species, and so are
likely to detect airgun noise (Kaifu et al.,
2008; Hu et al., 2009; Mooney et al.,
2010; Samson et al., 2014). Cephalopods
have a specialized sensory organ inside
the head called a statocyst that may help
an animal determine its position in
space (orientation) and maintain
balance (Budelmann, 1992). Packard et
al. (1990) showed that cephalopods
were sensitive to particle motion, not
sound pressure, and Mooney et al.
(2010) demonstrated that squid
statocysts act as an accelerometer
through which particle motion of the
sound field can be detected. Auditory
injuries (lesions occurring on the
statocyst sensory hair cells) have been
reported upon controlled exposure to
low-frequency sounds, suggesting that
cephalopods are particularly sensitive to
low-frequency sound (Andre et al.,
2011; Sole et al., 2013); however, these
controlled exposures involved long
exposure to sounds dissimilar to airgun
pulses (i.e., 2 hours of continuous
exposure to 1-second sweeps, 50–400
Hz). Behavioral responses, such as
inking and jetting, have also been
reported upon exposure to low-
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frequency sound (McCauley et al.,
2000b; Samson et al., 2014).
Impacts to benthic communities from
impulsive sound generated by active
acoustic sound sources are not well
documented. There are no published
data that indicate whether threshold
shift injuries or effects of auditory
masking occur in benthic invertebrates,
and there are little data to suggest
whether sounds from seismic surveys
would have any substantial impact on
invertebrate behavior (Hawkins et al.,
2014), though some studies have
indicated no short-term or long-term
effects of airgun exposure (e.g.,
Andriguetto-Filho et al., 2005; Payne et
al., 2007; 2008; Boudreau et al., 2009).
Exposure to airgun signals was found to
significantly increase mortality in
scallops, in addition to causing
significant changes in behavioral
patterns and disruption of hemolymph
chemistry during exposure (Day et al.,
2017). However, the implications of this
finding are not straightforward, as the
authors state that the observed levels of
mortality were not beyond naturally
occurring rates. Fitzgibbon et al. (2017)
found significant changes to
hemolymph cell counts in spiny
lobsters subjected to repeated airgun
signals, with the effects lasting up to a
year post-exposure. However, despite
the high levels of exposure, direct
mortality was not observed. Further, in
reference to the study, Day et al. (2016)
stated that ‘‘[s]eismic surveys appear to
be unlikely to result in immediate large
scale mortality [ . . . ] and, on their
own, do not appear to result in any
degree of mortality’’ and that ‘‘[e]arly
stage lobster embryos showed no effect
from air gun exposure, indicating that at
this point in life history, they are
resilient to exposure and subsequent
recruitment should be unaffected.’’
There is little information concerning
potential impacts of noise on
zooplankton populations. However, one
recent study (McCauley et al., 2017)
investigated zooplankton abundance,
diversity, and mortality before and after
exposure to airgun noise, finding that
the exposure resulted in significant
depletion for more than half the taxa
present and that there were two to three
times more dead zooplankton after
airgun exposure compared with controls
for all taxa. The majority of taxa present
were copepods and cladocerans; for
these taxa, the range within which
effects on abundance were detected was
up to approximately 1.2 km. In order to
have significant impacts on r-selected
species such as plankton, the spatial or
temporal scale of impact must be large
in comparison with the ecosystem
concerned (McCauley et al., 2017). It is
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also possible that the findings reflect
avoidance by zooplankton rather than
mortality (McCauley et al., 2017).
Therefore, the large scale of effect
observed here is of concern—
particularly where repeated noise
exposure is expected—and further study
is warranted.
A modeling exercise was conducted
as a follow-up to the McCauley et al.
(2017) study, in order to assess the
potential for impacts on ocean
ecosystem dynamics and zooplankton
population dynamics (Richardson et al.,
2017). Richardson et al. (2017) found
that for copepods with a short life cycle
in a high-energy environment, a fullscale airgun survey would impact
copepod abundance up to three days
following the end of the survey,
suggesting that effects such as those
found by McCauley et al. (2017) would
not be expected to be detectable
downstream of the survey areas, either
spatially or temporally. However, these
findings are relevant for zooplankton
with rapid reproductive cycles in areas
where there is a high natural
replenishment rate resulting from new
water masses moving in, and the
findings may not apply in lower-energy
environments or for zooplankton with
longer life-cycles. In fact, the study
found that by turning off the current, as
may reflect lower-energy environments,
the time to recovery for the modelled
population extended from several days
to several weeks.
In the absence of further validation of
the McCauley et al. (2017) findings, if
we assume a worst-case likelihood of
severe impacts to zooplankton within
approximately 1 km of the acoustic
source, the large spatial scale and
expected wide dispersal of survey
vessels does not lead us to expect any
meaningful follow-on effects to the prey
base for odontocete predators (the
region is not an important feeding area
for taxa that feed directly on
zooplankton, i.e., mysticetes). While the
large scale of effect observed by
McCauley et al. (2017) may be of
concern, NMFS concludes that these
findings indicate a need for more study,
particularly where repeated noise
exposure is expected—a condition
unlikely to occur in relation to the time
period in which the surveys considered
for the five IHAs will take place.
A recent review article concluded
that, while laboratory results provide
scientific evidence for high-intensity
and low-frequency sound-induced
physical trauma and other negative
effects on some fish and invertebrates,
the sound exposure scenarios in some
cases are not realistic to those
encountered by marine organisms
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during routine seismic operations
(Carroll et al., 2017). The review finds
that there has been no evidence of
reduced catch or abundance following
seismic activities for invertebrates, and
that there is conflicting evidence for fish
with catch observed to increase,
decrease, or remain the same. Further,
where there is evidence for decreased
catch rates in response to airgun noise,
these findings provide no information
about the underlying biological cause of
catch rate reduction (Carroll et al.,
2017).
As addressed earlier in ‘‘Comments
and Responses,’’ some members of the
public made strong assertions regarding
the likely effects of airgun survey noise
on marine mammal prey. These
assertions included, for example, that
the specified activities would harm fish
and invertebrate species over the longterm, cause reductions in recruitment
and effects to behavior that may reduce
reproductive potential and foraging
success and increase the risk of
predation, and induce changes in
community composition via such
population-level impacts. We have
addressed these claims both in our
comment responses and in our review of
the available literature, above. We also
reviewed available information
regarding populations of representative
prey stocks in the northern Gulf of
Mexico (GOM), which is the only U.S.
location where marine seismic surveys
are a routinely occurring activity. While
we recognize the need for caution in
assuming correlation between the
ongoing survey activity in the GOM and
the health of assessed stocks there, we
believe this information has some value
in informing the likelihood of
population-level effects to prey species
and, therefore, the likelihood that the
specified activities would negatively
impact marine mammal populations via
effects to prey. We note that the
information reported below is in context
of managed commercial and recreational
fishery exploitation, in addition to any
other impacts (e.g., noise) on the stocks.
The species listed below are known
prey species for marine mammals and
represent groups with different life
histories and patterns of habitat use.
• Red snapper (Lutjanus
campechanus): Red snapper are bottomdwelling fish generally found at
approximately 10–190 m deep that
typically live near hard structures on
the continental shelf that have moderate
to high relief (for example, coral reefs,
artificial reefs, rocks, ledges, and caves),
sloping soft-bottom areas, and limestone
deposits. Larval snapper swim freely
within the water column. Increases in
total and spawning stock biomass are
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predicted beginning in about 1990
(Cass-Calay et al., 2015). Regional
estimates suggest that recruitment in the
west has generally increased since the
1980s, and has recently been above
average, while recruitment in the east
peaked in the mid-2000s, and has since
declined. However, the most recent
assessment suggests a less significant
decline (to moderate levels) (Cass-Calay
et al., 2015).
• Yellowfin tuna (Thunnus
albacares): Yellowfin tuna are highly
migratory, living in deep pelagic waters,
and spawn in the GOM from May to
August. However, we note that a single
stock is currently assumed for the entire
Atlantic, with additional spawning
grounds in the Gulf of Guinea,
Caribbean Sea, and off Cabo Verde. The
most recent assessment indicates that
spawning stock biomass for yellowfin
tuna is stable or increasing somewhat
and that, overall, the stock is near levels
that produce the maximum sustainable
yield (ICCAT, 2016).
• King mackerel (Scomberomorus
cavalla): King mackerel are a coastal
pelagic species, found in open waters
near the coast in waters from
approximately 35–180 m deep. King
mackerel migrate in response to changes
in water temperature, and spawn in
shelf waters from May through October.
Estimates of recruitment demonstrate
normal cyclical patterns over the past 50
years, with a period of higher
recruitment most recently (1990–2007)
(SEDAR, 2014). Long-term spawning
stock biomass patterns indicate that the
spawning stock has been either
rebuilding or remained relatively
consistent over the last 20 years, with
nothing indicating that the stock has
declined in these recent decades
(SEDAR, 2014).
In summary, impacts of the specified
activities will likely be limited to
behavioral responses, the majority of
prey species will be capable of moving
out of the project area during surveys,
a rapid return to normal recruitment,
distribution, and behavior for prey
species is anticipated, and, overall,
impacts to prey species will be minor
and temporary. Prey species exposed to
sound might move away from the sound
source, experience TTS, experience
masking of biologically relevant sounds,
or show no obvious direct effects.
Mortality from decompression injuries
is possible in close proximity to a
sound, but only limited data on
mortality in response to airgun noise
exposure are available (Hawkins et al.,
2014). The most likely impacts for most
prey species in a given survey area
would be temporary avoidance of the
area. Surveys using towed airgun arrays
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move through an area relatively quickly,
limiting exposure to multiple impulsive
sounds. In all cases, sound levels would
return to ambient once a survey moves
out of the area or ends and the noise
source is shut down and, when
exposure to sound ends, behavioral and/
or physiological responses are expected
to end relatively quickly (McCauley et
al., 2000b). The duration of fish
avoidance of a given area after survey
effort stops is unknown, but a rapid
return to normal recruitment,
distribution, and behavior is
anticipated. While the potential for
disruption of spawning aggregations or
schools of important prey species can be
meaningful on a local scale, the mobile
and temporary nature of most surveys
and the likelihood of temporary
avoidance behavior suggest that impacts
would be minor.
Based on the information discussed
herein, we reaffirm our conclusion that
impacts of the specified activities are
not likely to have more than short-term
adverse effects on any prey habitat or
populations of prey species. Further,
any impacts to marine mammal habitat
are not expected to result in significant
or long-term consequences for
individual marine mammals, or to
contribute to adverse impacts on their
populations.
Estimated Take
This section provides information
regarding the number of incidental takes
authorized, which informs both NMFS’s
consideration of ‘‘small numbers’’ and
the negligible impact determinations.
Except with respect to certain
activities not pertinent here, section
3(18) of the MMPA defines
‘‘harassment’’ as: Any act of pursuit,
torment, or annoyance which (i) has the
potential to injure a marine mammal or
marine mammal stock in the wild (Level
A harassment); or (ii) has the potential
to disturb a marine mammal or marine
mammal stock in the wild by causing
disruption of behavioral patterns,
including, but not limited to, migration,
breathing, nursing, breeding, feeding, or
sheltering (Level B harassment).
Anticipated takes would primarily be
by Level B harassment, as use of the
acoustic sources (i.e., airgun arrays) can
result in disruption of behavioral
patterns for individual marine
mammals. There is also some potential
for auditory injury (Level A harassment)
to result for low- and high-frequency
species due to the size of the predicted
auditory injury zones for those species.
We do not expect auditory injury to
occur for mid-frequency species, as
discussed in greater detail below. The
required mitigation and monitoring
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measures are expected to minimize the
severity of such taking to the extent
practicable. It is unlikely that lethal
takes would occur even in the absence
of the mitigation and monitoring
measures, and no such takes are
anticipated or authorized. Below we
describe how the authorized take was
estimated using acoustic thresholds,
sound field modeling, and marine
mammal density data.
Acoustic Thresholds
NMFS uses acoustic thresholds that
identify the received level of
underwater sound above which exposed
marine mammals generally would be
reasonably expected to exhibit
disruption of behavioral patterns
(equated to Level B harassment) or to
incur PTS of some degree (equated to
Level A harassment).
Level B Harassment—Although
available data are consistent with the
basic concept that louder sounds evoke
more significant behavioral responses
than softer sounds, defining precise
sound levels that will potentially
disrupt behavioral patterns is difficult
because responses depend on the
context in which the animal receives the
sound, including an animal’s behavioral
mode when it hears sounds (e.g.,
feeding, resting, or migrating), prior
experience, and biological factors (e.g.,
age and sex). Some species, such as
beaked whales, are known to be more
highly sensitive to certain
anthropogenic sounds than other
species. Other contextual factors, such
as signal characteristics, distance from
the source, duration of exposure, and
signal to noise ratio, may also help
determine response to a given received
level of sound. Therefore, levels at
which responses occur are not
necessarily consistent and can be
difficult to predict (Southall et al., 2007;
Ellison et al., 2012; Bain and Williams,
2006).
However, based on the practical need
to use a relatively simple threshold
based on available information that is
both predictable and measurable for
most activities, NMFS has historically
used a generalized acoustic threshold
based on received level to estimate the
onset of Level B harassment. These
thresholds are 160 dB rms (intermittent
sources, which include impulsive
sources) and 120 dB rms (continuous
sources). Airguns are impulsive sound
sources; therefore, the 160 dB rms
threshold is appropriate for use in
evaluating effects from the specified
activities.
Level A Harassment—NMFS’s
Technical Guidance for Assessing the
Effects of Anthropogenic Sound on
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Marine Mammal Hearing (NMFS, 2018)
identifies dual criteria to assess the
potential for auditory injury (Level A
harassment) to occur for different
marine mammal groups (based on
hearing sensitivity) as a result of
exposure to noise. The technical
guidance identifies the received levels,
or thresholds, above which individual
marine mammals are predicted to
experience changes in their hearing
sensitivity for all underwater
anthropogenic sound sources, and
reflects the best available science on the
potential for noise to affect auditory
sensitivity by:
• Dividing sound sources into two
groups (i.e., impulsive and nonimpulsive) based on their potential to
affect hearing sensitivity;
• Choosing metrics that best address
the impacts of noise on hearing
sensitivity, i.e., peak sound pressure
level (peak SPL) (reflects the physical
properties of impulsive sound sources
to affect hearing sensitivity) and
cumulative sound exposure level (cSEL)
(accounts for not only level of exposure
but also duration of exposure); and
• Dividing marine mammals into
hearing groups and developing auditory
weighting functions based on the
science supporting that not all marine
mammals hear and use sound in the
same manner.
The premise of the dual criteria
approach is that, while there is no
definitive answer to the question of
which acoustic metric is most
appropriate for assessing the potential
for injury, both the received level and
duration of received signals are
important to an understanding of the
potential for auditory injury. Therefore,
peak SPL is used to define a pressure
criterion above which auditory injury is
predicted to occur, regardless of
exposure duration (i.e., any single
exposure at or above this level is
considered to cause auditory injury),
and cSEL is used to account for the total
energy received over the duration of
sound exposure (i.e., both received level
and duration of exposure) (Southall et
al., 2007; NMFS, 2018). As a general
principle, whichever criterion is
exceeded first (i.e., results in the largest
isopleth) would be used as the effective
injury criterion (i.e., the more
precautionary of the criteria). Note that
cSEL acoustic threshold levels
incorporate marine mammal auditory
weighting functions, while peak
pressure thresholds do not (i.e., flat or
unweighted). Weighting functions for
each hearing group (e.g., low-, mid-, and
high-frequency cetaceans) are described
in NMFS (2018).
NMFS (2018) recommends 24 hours
as a maximum accumulation period
relative to cSEL thresholds. These
thresholds were developed by
compiling and synthesizing the best
available science, and are provided in
Table 3 below. The references, analysis,
and methodology used in the
development of the thresholds are
described in NMFS (2018), and more
information is available online at:
www.fisheries.noaa.gov/national/
marine-mammal-protection/marinemammal-acoustic-technical-guidance.
TABLE 3—EXPOSURE CRITERIA FOR AUDITORY INJURY FOR IMPULSIVE SOURCES
Peak pressure 1
(dB)
Hearing group
Low-frequency cetaceans ............................................................................................................................
Mid-frequency cetaceans .............................................................................................................................
High-frequency cetaceans ...........................................................................................................................
1 Referenced
2 Referenced
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183
185
155
to 1 μPa; unweighted within generalized hearing range.
to 1 μPa2s; weighted according to appropriate auditory weighting function.
NMFS considers these updated
thresholds and associated weighting
functions to be the best available
information for assessing whether
exposure to specific activities is likely
to result in changes in marine mammal
hearing sensitivity.
Sound Field Modeling
BOEM’s PEIS (BOEM, 2014a) provides
information related to estimation of the
sound fields that would be generated by
potential geophysical survey activity on
the mid- and south Atlantic OCS. We
provide a brief summary of that
modeling effort here; for more
information, please see our Notice of
Proposed IHAs. For full detail, please
see Appendix D of BOEM’s PEIS (Zykov
and Carr, 2014 in BOEM, 2014a). The
acoustic modeling generated a threedimensional acoustic propagation field
as a function of source characteristics
and physical properties of the ocean for
later integration with marine mammal
density information in an animal
movement model to estimate potential
acoustic exposures.
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230
202
Cumulative sound
exposure level 2
(dB)
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The authors selected 15 modeling
sites throughout BOEM’s mid-Atlantic
and south Atlantic OCS planning areas
for use in modeling predicted sound
fields resulting from use of the airgun
array. The water depth at the sites
varied from 30–5,400 m. Two types of
bottom composition were considered:
Sand and clay, their selection
depending on the water depth at the
source. Twelve possible sound speed
profiles for the water column were used
to cover the variation of the sound
velocity distribution in the water with
location and season. Twenty-one
distinct propagation scenarios resulted
from considering different sound speed
profiles at some of the modeling sites.
Two acoustic propagation models were
employed to estimate the acoustic field
radiated by the sound sources. A
version of JASCO Applied Science’s
Marine Operations Noise Model
(MONM), based on the Rangedependent Acoustic Model (RAM)
parabolic-equations model, MONM–
RAM, was used to estimate the SELs for
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low-frequency sources (below 2 kHz)
such as an airgun array. For more
information on sound propagation
model types, please see, e.g., Etter
(2013). The model takes into account
the geoacoustic properties of the sea
bottom, vertical sound speed profile in
the water column, range-dependent
bathymetry, and the directivity of the
source. The directional source levels for
the airgun array were modeled using the
Airgun Array Source Model (AASM)
based on the specifications of the source
such as the arrangement and volume of
the guns, firing pressure, and depth
below the sea surface. The modeled
directional source levels were used as
the input for the acoustic propagation
model. For background information on
major factors affecting underwater
sound propagation, please see Zykov
and Carr (2014).
The modeling used a 5,400 in3 airgun
array as a representative example. The
array has dimensions of 16 x 15 m and
consists of 18 air guns placed in three
identical strings of six air guns each
(please see Figure D–6 of Zykov and
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Carr (2014)). The volume of individual
air guns ranges from 105–660 in3. Firing
pressure for all elements is 2,000 psi.
The depth below the sea surface for the
array was set at 6.5 m. Please see Table
1 for a comparison to the airgun arrays
planned for use by the applicant
companies. Horizontal third-octave
band directionality plots resulting from
source modeling are shown in Figure D–
8 of Zykov and Carr (2014). The
estimated received levels are expressed
in terms of the SEL metric over the
duration of a single source pulse. For
the purposes of this study, the SEL
results were converted to the rms SPL
metric using a range dependent
conversion coefficient.
Four depth regions were classified
based on bathymetry: Shallow
continental shelf (<60 m); continental
shelf (60–150 m); continental slope
(150–1,000 m); and deep ocean (>1,000
m). The modeling results show that the
largest threshold radii are typically
associated with sites in intermediate
water depths (250 and 900 m). Low
frequencies propagate relatively poorly
in shallow water (i.e., water depths on
the same order as or less than the
wavelength). At intermediate water
depths, this stripping of low-frequency
sound no longer occurs, and longerrange propagation can be enhanced by
the channeling of sound caused by
reflection from the surface and seafloor
(depending on the nature of the sound
speed profile and sediment type). Table
4 shows scenario-specific modeling
results for distances to the 160 dB level;
results presented are for the 95 percent
range to threshold.
TABLE 4—MODELING SCENARIOS AND SITE-SPECIFIC MODELED THRESHOLD RADII FROM BOEM’S PEIS
Water depth
(m)
Scenario No.
Site No.1
1 ........................
2 ........................
3 ........................
4 ........................
5 ........................
6 ........................
7 ........................
8 ........................
9 ........................
10 ......................
11 ......................
12 ......................
13 ......................
14 ......................
15 ......................
16 ......................
17 ......................
18 ......................
19 ......................
20 ......................
21 ......................
1 .......................
2 .......................
3 .......................
4 .......................
5 .......................
1 .......................
6 .......................
3 .......................
7 .......................
8 .......................
1 .......................
6 .......................
3 .......................
9 .......................
10 .....................
11 .....................
12 .....................
13 .....................
3 .......................
14 .....................
15 .....................
Mean ..........
...........................
Threshold radii
(m) 2
Season
Bottom type
5,390
2,560
880
249
288
5,390
3,200
880
251
249
5,390
3,200
880
275
4,300
3,010
4,890
3,580
880
100
51
Winter ......................................
Winter ......................................
Winter ......................................
Winter ......................................
Winter ......................................
Spring ......................................
Spring ......................................
Spring ......................................
Spring ......................................
Spring ......................................
Summer ...................................
Summer ...................................
Summer ...................................
Summer ...................................
Fall ...........................................
Fall ...........................................
Fall ...........................................
Fall ...........................................
Fall ...........................................
Fall ...........................................
Fall ...........................................
Clay .........................................
Clay .........................................
Sand ........................................
Sand ........................................
Sand ........................................
Clay .........................................
Clay .........................................
Sand ........................................
Sand ........................................
Sand ........................................
Clay .........................................
Clay .........................................
Sand ........................................
Sand ........................................
Clay .........................................
Clay .........................................
Clay .........................................
Clay .........................................
Sand ........................................
Sand ........................................
Sand ........................................
4,969
5,184
8,104
8,725
8,896
4,989
5,026
8,056
8,593
8,615
4,973
5,013
8,095
9,122
5,121
5,098
4,959
5,069
8,083
8,531
8,384
..............................
..................................................
..................................................
6,838
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Adapted from Tables D–21 and D–22 of Zykov and Carr (2014).
1 Please see Figure D–35 of Zykov and Carr (2014) for site locations.
2 Threshold radii to 160 dB (rms) SPL, 95 percent range.
We provide this description of the
modeling performed for BOEM’s PEIS as
a general point of reference for the
surveys, and also because three of the
applicant companies—TGS, CGG, and
Western—directly used these results to
inform their exposure modeling, rather
than performing separate sound field
modeling. As described by BOEM
(2014a), the modeled array was selected
to be representative of the large airgun
arrays likely to be used by geophysical
exploration companies in the mid- and
south Atlantic OCS. Therefore, we use
the BOEM (2014a) results as a
reasonable proxy for those three
companies (please see ‘‘Detailed
Description of Activities’’ for further
description of the acoustic sources
planned for use by these three
companies). ION and Spectrum elected
to perform separate sound field
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modeling efforts, and these are
described below.
ION—ION provided information
related to estimation of the sound fields
that would be generated by their
geophysical survey activity on the midand south Atlantic OCS. We provide a
brief summary of that modeling effort
here; for more information, please see
our Notice of Proposed IHAs. For full
detail, please see Appendix A of ION’s
application (Li, 2014; referred to
hereafter as Appendix A of ION’s
application). ION plans to use a 36element airgun array with a 6,420 in3
total firing volume (please see ‘‘Detailed
Description of Activities’’ for further
description of ION’s acoustic source).
The modeling assumed that ION would
operate from July to December. Sixteen
representative sites were selected along
survey track lines planned by ION for
use in modeling predicted sound fields
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resulting from use of the airgun array
(see Figure 2 in Appendix A of ION’s
application for site locations). Two
acoustic propagation models were
employed to estimate the acoustic field
radiated by the sound sources. As was
described above for BOEM’s PEIS, the
acoustic signature of the airgun array
was predicted using AASM and MONM
was used to calculate the sound
propagation and acoustic field near each
defined site. The modeling process
follows generally that described
previously for BOEM’s PEIS. Key
differences are the characteristics of the
acoustic source (see Table 1), locations
of the modeled sites, and the use of a
restricted set of sound velocity profiles
(e.g., fall and winter). Site-specific
modeling results for distances to the 160
dB rms level were presented in Table 8
of our Notice of Proposed IHAs and are
not reprinted here; mean result for the
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95 percent range to threshold was 5,836
m.
Spectrum—Spectrum provided
information related to estimation of the
sound fields that would be generated by
their geophysical survey activity on the
mid- and south Atlantic OCS. We
provide a brief summary of that
modeling effort here; for more
information, please see our Notice of
Proposed IHAs. For full detail, please
see Appendix A of Spectrum’s
application (Frankel et al., 2015;
referred to hereafter as Appendix A of
Spectrum’s application). Spectrum
plans to use a 32-element airgun array
with a 4,920 in3 total firing volume
(please see ‘‘Detailed Description of
Activities’’ for further description of
Spectrum’s acoustic source). Array
characteristics were input into the
GUNDALF model to calculate the
source level and predict the array
signature. The directivity pattern of the
airgun array was calculated using the
beamforming module in the
CASS-GRAB acoustic propagation
model. These models provided source
input information for the
range-dependent acoustic model (RAM),
which was then used to predict acoustic
propagation and estimate the resulting
sound field. The RAM model creates
frequency-specific, three-dimensional
directivity patterns (sound field) based
upon the size and location of each
airgun in the array. As described
previously, physical characteristics of
the underwater environment (e.g.,
sound velocity profile, bathymetry,
substrate composition) are critical to
understanding acoustic propagation; 16
modeling locations were selected that
span the acoustic conditions of the
survey area. Spectrum elected to use
sound velocity profiles for winter and
spring and assumed that half of the
survey would occur in winter and half
in spring. Site-specific modeling results
for distances to the 160 dB rms level
were presented in Table 9 of our Notice
of Proposed IHAs and are not reprinted
here; mean result for the 95 percent
range to threshold was 9,775 m.
Marine Mammal Density Information
The best available scientific
information was considered in
conducting marine mammal exposure
estimates (the basis for estimating take).
Historically, distance sampling
methodology (Buckland et al., 2001) has
been applied to visual line-transect
survey data to estimate abundance
within large geographic strata (e.g.,
Fulling et al., 2003; Mullin and Fulling,
2004; Palka, 2006). Design-based
surveys that apply such sampling
techniques produce stratified
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abundance estimates and do not provide
information at appropriate
spatiotemporal scales for assessing
environmental risk of a planned survey.
To address this issue of scale, efforts
were developed to relate animal
observations and environmental
correlates such as sea surface
temperature in order to develop
predictive models used to produce finescale maps of habitat suitability (e.g.,
Waring et al., 2001; Hamazaki, 2002;
Best et al., 2012). However, these
studies generally produce relative
estimates that cannot be directly used to
quantify potential exposures of marine
mammals to sound, for example. A more
recent approach known as density
surface modeling couples traditional
distance sampling with multivariate
regression modeling to produce density
maps predicted from fine-scale
environmental covariates (e.g., DoN,
2007; Becker et al., 2014; Roberts et al.,
2016).
At the time the applications were
initially developed, the best available
information concerning marine mammal
densities in the survey area was the U.S.
Navy’s Navy Operating Area (OPAREA)
Density Estimates (NODEs) (DoN, 2007).
These habitat-based cetacean density
models utilized vessel-based and aerial
survey data collected by NMFS from
1998–2005 during broad-scale
abundance studies. Modeling
methodology is detailed in DoN (2007).
A more advanced cetacean density
modeling effort, described in Roberts et
al. (2016), was ongoing during initial
development of the applications, and
the model outputs were made available
to the applicant companies. All
information relating to this effort was
made publicly available in March 2016.
Roberts et al. (2016) provided several
key improvements with respect to the
NODEs effort, by incorporating
additional aerial and shipboard survey
data from NMFS and from other
organizations collected over the period
1992–2014, incorporating 60 percent
more shipboard and 500 percent more
aerial survey hours than did NODEs;
controlling for the influence of sea state,
group size, availability bias, and
perception bias on the probability of
making a sighting; and modeling density
from an expanded set of eight
physiographic and 16 dynamic
oceanographic and biological covariates.
There are multiple reasons why marine
mammals may be undetected by
observers. Animals are missed because
they are underwater (availability bias) or
because they are available to be seen,
but are missed by observers (perception
and detection biases) (e.g., Marsh and
Sinclair, 1989). Negative bias on
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perception or detection of an available
animal may result from environmental
conditions, limitations inherent to the
observation platform, or observer
ability. Therefore, failure to correct for
these biases may lead to underestimates
of cetacean abundance (e.g., NMFS’s
SAR estimates fail to correct for
availability bias). Use of additional data
was used to improve detection functions
for taxa that were rarely sighted in
specific survey platform configurations.
The degree of underestimation would
likely be particularly high for species
that exhibit long dive times or are
cryptic, such as sperm whales or beaked
whales. In summary, consideration of
additional survey data and an improved
modeling strategy allowed for an
increased number of taxa modeled and
better spatiotemporal resolutions of the
resulting predictions. In general, we
consider the models produced by
Roberts et al. (2016) to be the best
available source of data regarding
cetacean density in the Atlantic. More
information, including the model results
and supplementary information for each
model, is available at
seamap.env.duke.edu/models/Duke-ECGOM-2015/.
Aerial and shipboard survey data
produced by the Atlantic Marine
Assessment Program for Protected
Species (AMAPPS) program provides an
additional source of information
regarding marine mammal presence in
the survey areas. These surveys
represent a collaborative effort between
NMFS, BOEM, and the Navy. Although
the cetacean density models described
above do include survey data from
2010–14, the AMAPPS data for those
years was not made available to the
model authors. Future model updates
will incorporate these data, but
currently the AMAPPS data comprise a
separate source of information (e.g.,
NMFS, 2010a, 2011, 2012, 2013a, 2014,
2015a).
Cetacean density predictions
provided by the Roberts et al. (2016)
models are in most cases limited to the
U.S. EEZ. However, the planned survey
areas extend beyond the EEZ out to 350
nmi. Because specific modeling results
were not available for this region at the
time the exposure estimates were
developed, the Roberts et al. (2016)
model predictions were extrapolated out
to the additional area (described in
further detail below). Newer modeling
products regarding cetacean densities in
areas of the western North Atlantic
beyond the EEZ became available
(Mannocci et al., 2017) following
development of the exposure estimates;
however, this information was not
reasonably available to the applicants in
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developing their applications or to
NMFS in preparing the Notice of
Proposed IHAs. Therefore, we retain use
of the extrapolated density values from
Roberts et al. (2016) in estimating
potential exposures in the region
beyond the EEZ; this approach remains
reasonably representative of cetacean
densities in the portion of the specific
geographic region outside the EEZ.
North Atlantic Right Whale—
Following publication of our Notice of
Proposed IHAs, we became aware of an
effort by Roberts et al. to update certain
density models, including for the North
Atlantic right whale. In contrast to other
new information that was not
reasonably available to us in developing
the exposure estimates discussed herein
(e.g., Mannocci et al., 2017 and
additional Roberts et al. model revisions
(discussed below)), we determined that
the revised North Atlantic right whale
models represent a significant
improvement to the available
information. These updates greatly
expanded the dataset used to derive
density outputs, especially within the
action area, as they incorporated both
AMAPPs data as well as data from aerial
surveys conducted by several
organizations in the southeast United
States. By including these additional
data sources, the number of right whale
sightings used to inform the models
within the action area increased by over
2,500 sightings (approximately 40
sightings in the 2015 model versus
approximately 2,560 sightings in the
2017 model) (Roberts et al., 2017). In
addition, the updated models
incorporated several improvements to
minimize known biases and used an
improved seasonal definition that more
closely aligns with right whale biology.
Importantly, the updated model outputs
showed a strong relationship between
right whale abundance in the action
area and distance to shore out to
approximately 80 km (Roberts et al.,
2017)—the same relationship was
indicated as being out to approximately
50 km by the previous model version
(Roberts et al., 2016). As a result of these
significant model improvements and in
context of the significant concern
regarding North Atlantic right whale
status, we determined it necessary to
produce revised exposure estimates for
the North Atlantic right whale
(described in further detail below). As
stated by the authors, their goal in
updating the right whale model was to
re-examine all aspects of the model and
make as many improvements as
possible. This updated model represents
the best available scientific information
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regarding North Atlantic right whale
density and distribution.
We note that, in addition to the
models for North Atlantic right whales,
Roberts et al. (2017) presented updated
models for 10 additional taxa (fin,
humpback, minke, sei, and sperm
whales; separate models for Cuvier’s,
Mesoplodont, and unidentified beaked
whales; pilot whales; and harbor
porpoise). While these models
incorporate several improvements
(additional data (although mostly
outside of the action area), new seasonal
definitions, updates to better correct for
known biases), we evaluated the model
outputs as being generally similar to
those produced by Roberts et al. (2016).
Thus, while the Roberts et al. (2017)
models for these additional species
likely represent minor improvements
over the Roberts et al. (2016) models for
these species, they are unlikely to result
in meaningful differences if used in an
exposure analysis. That is, we consider
both the Roberts et al. (2016) and
Roberts et al. (2017) model outputs the
best available density estimates for these
additional species, and estimates of
exposure based on the outputs of one
model are unlikely to be meaningfully
different than estimates based on
outputs from the other. Therefore,
because these revised models were not
available to us at the time of initial
development of the exposure estimates
and do not represent a significant
improvement in the state of available
scientific information, as do the updated
right whale models, we did not request
these updated models from the authors
and retain use of the 2015 model
version for these taxa.
Description of Exposure Estimates
Here, we provide applicant-specific
descriptions of the processes employed
to estimate potential exposures of
marine mammals to given levels of
received sound. The discussions
provided here are specific to estimated
exposures at or above the criterion for
Level B harassment (i.e., 160 dB rms);
we provide a separate discussion below
regarding our consideration of potential
Level A harassment. We provide a brief
summary of the exposure modeling
process performed for BOEM’s PEIS as
a point of reference; for more
information, please see our Notice of
Proposed IHAs. For full detail, see
Appendix E of the PEIS (BOEM, 2014a).
This description builds on the
description of sound field modeling
provided earlier in this section and in
Appendix D of BOEM’s PEIS. As
described previously, 21 distinct
acoustic propagation regions were
defined. Reflecting seasonal differences
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in sound velocity profiles, these regions
were specific to each season. Using the
NODEs data, the average density of each
species was then numerically
determined for each region. However,
the NODEs models do not provide
outputs for the extended continental
shelf areas seaward of the EEZ;
therefore, known density information at
the edge of the area modeled by NODEs
was extrapolated to the remainder of the
study area.
The results of the acoustic modeling
exercise (i.e., estimated 3D sound field)
and the region-specific density
estimates were then input into MAI’s
Acoustic Integration Model (AIM). AIM
is a software package developed to
predict the exposure of receivers (e.g.,
an animal) to any stimulus propagating
through space and time through use of
a four-dimensional, individual-based,
Monte Carlo-based statistical model.
Within the model, simulated marine
animals (i.e., animats) may be
programmed to behave in specific ways
on the basis of measured field data. An
animat movement engine controls the
geographic and vertical movements
(e.g., speed and direction) of sound
sources and animats through four
dimensions (time and space) according
to user inputs.
Species-specific animats were created
with programmed behavioral parameters
describing dive depth, surfacing and
dive durations, swimming speed, course
change, and behavioral aversions (e.g.,
water too shallow). The programmed
animats were then randomly distributed
over a given bounded simulation area.
Because the exact positions of sound
sources and animals are not known in
advance for proposed activities,
multiple runs of realistic predictions are
used to provide statistical validity to the
simulated scenarios. Each speciesspecific simulation is seeded with a
given density of animats. A separate
simulation was created and run for each
combination of location, movement
pattern, and marine mammal species.
A model run consists of a userspecified number of steps forward in
time, in which each animat is moved
according to the rules describing its
behavior. For each time step of the
model run, the received sound levels at
each animat (i.e., each marine mammal)
are calculated. AIM returns the
movement patterns of the animats, and
the received sound levels are calculated
separately using the given acoustic
propagation predictions at different
locations. At the end of each time step,
an animat ‘‘evaluates’’ its environment,
including its 3D location, the time, and
any received sound level.
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Animat positions relative to the
acoustic source (i.e., range, bearing, and
depth) were used to extract received
level estimates from the acoustic
propagation modeling results. The
source levels, and therefore
subsequently the received levels,
include the embedded corrections for
signal pulse length and M-weighting. Mweighting is a type of frequency
weighting curve intended to reflect the
differential potential for sound to affect
marine mammals based on their
sensitivity to the particular frequencies
produced (Southall et al., 2007). Please
see Appendix D of BOEM’s PEIS for
further description of the application of
M-weighting filters. For each bearing,
distance, and depth from the source, the
received level values were expressed as
SPLs (rms) with units of dB re 1m Pa.
These are then converted back to
intensity and summed over the duration
of the exercise to generate an integrated
energy level, expressed in terms of dB
re 1 mPa2-sec or dB SEL. The number of
animats per species that exceeded a
given criterion (e.g., 160 dB rms) may
then be determined, and these results
scaled according to the relationship of
model-to-real world densities per
species. That is, the exposure results are
corrected using the actual species- and
region-specific density derived from the
density model outputs (as described
above) to give real-world estimates of
exposure to sound exceeding a given
received level.
As noted previously, the NODEs
models (DoN, 2007) provided the best
available information at the time of
initial development for these
applications. Outputs of the cetacean
density models described by Roberts et
al. (2016) were subsequently made
available to the applicant companies,
which, with the exception of CGG, had
previously submitted applications. Two
applicants (TGS and Western) elected to
consider the new information and
produced revised applications
accordingly. CGG used the Roberts et al.
(2016) models in developing their
application. Two applicants (Spectrum
and ION) declined to use the Roberts et
al. (2016) density models. However, we
worked with MAI—which performed
the initial exposure modeling provided
in the Spectrum and ION applications—
to produce revised exposure estimates
utilizing the outputs of the Roberts et al.
(2016) density models.
In order to revise the exposure
estimates for Spectrum and ION, we
first extracted appropriate density
estimates from the Roberts et al. (2016)
model outputs. Because both Spectrum
and ION used modeling processes
conceptually similar to that described
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above for BOEM’s PEIS, these density
estimates would replace those
previously derived from the NODEs
models in rescaling the exposure
estimation results from those derived
from animal movement modeling using
a user-specified density. The steps
involved in calculating mean marine
mammal densities over the 21 modeling
areas used in both BOEM’s PEIS and the
applications were described in our
Notice of Proposed IHAs, and are not
repeated here. As was the case for the
NODEs model outputs, the Roberts et al.
(2016) model outputs are restricted to
the U.S. EEZ. Therefore, we similarly
extended the edge densities to cover the
area outside of the data extent. This
process was also described in our Notice
of Proposed IHAs, and is not repeated
here.
Spectrum—Spectrum’s sound field
estimation process was previously
described, and their exposure modeling
process is substantially similar to that
described above for BOEM’s PEIS.
Spectrum’s exposure modeling process
was described in full in our Notice of
Proposed IHAs; please see that
document for more detail. As described
previously, Spectrum limited their
analysis to winter and spring seasons
and therefore used only ten of the 21
seasonal propagation acoustic regions.
Half of the survey activity was assumed
to occur in winter and half in spring.
In summary, the original exposure
results were obtained using AIM to
model source and animat movements,
with received SEL for each animat
predicted at a 30-second time step. This
predicted SEL history was used to
determine the maximum SPL (rms or
peak) and cSEL for each animat, and the
number of exposures exceeding relevant
criteria recorded. The number of
exposures are summed for all animats to
get the number of exposures for each
species, with that summed value then
scaled by the ratio of real-world density
to the model density value. The final
scaling value was the ratio of the length
of the modeled survey line to the length
of survey line in each modeling region.
The exposure estimates provided in
Spectrum’s application were based on
the NODEs model outputs. In order to
make use of the best available
information (i.e., Roberts et al. (2016)),
we extracted species- and regionspecific density values as described
above. These were provided to MAI in
order to rescale the original exposure
results produced using the seeded
animat density; revised exposure
estimates are shown in Table 6.
As stated above, Spectrum notified
NMFS on June 26, 2018, of a
modification to their survey plan. Note
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that analysis corresponding with
Spectrum’s original survey plan is
retained here, in ‘‘Estimated Take.’’
Please see ‘‘Spectrum Survey Plan
Modification’’ for further information
and for revised (and authorized) take
numbers (Table 17) relating to
Spectrum’s modified survey plan.
ION—ION’s sound field estimation
process was previously described, and
their exposure modeling process is
substantially similar to that described
above for BOEM’s PEIS (and for
Spectrum). ION’s exposure modeling
process was described in full in our
Notice of Proposed IHAs; please see that
document for more detail. The same
acoustic propagation regions described
for BOEM’s PEIS were used by ION for
exposure modeling; however, ION
limited their analysis to summer and
fall seasons and therefore used only 11
of the 21 regions. Whichever season
returned the higher number of estimated
exposures for a given species was
assumed to be the season in which the
survey occurred, i.e., ION’s requested
take authorization corresponds to the
higher of the two seasonal speciesspecific exposure estimates.
In summary, the original exposure
results were obtained using AIM to
model source and animat movements,
with received SEL for each animat
predicted at a 30-second time step. This
predicted SEL history was used to
determine the maximum SPL (rms or
peak) and cSEL for each animat, and the
number of exposures exceeding relevant
criteria recorded. The number of
exposures are summed for all animats to
get the number of exposures for each
species, with that summed value then
scaled by the ratio of real-world density
to the model density value. The final
scaling value was the ratio of the length
of the modeled survey line to the length
of survey line in each modeling region.
As described above, the exposure
estimates provided in ION’s application
were based on the NODEs model
outputs. In order to make use of the best
available information (i.e., Roberts et al.
(2016)), we extracted species- and
region-specific density values as
described above. These were provided
to MAI in order to rescale the original
exposure results produced using the
seeded animat density; revised exposure
estimates are shown in Table 6.
TGS—TGS did not conduct their own
sound field modeling, instead relying on
the sound field estimates provided by
BOEM (2014a). For purposes of
exposure modeling, TGS considered
threshold radii for three depth bins:
<880 m, 880–2,560 m, >2,560 m (note
that there are no sound field modeling
sites at depths between 880–2,560 m).
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When considering the 21 modeling
scenarios across the 15 sites, threshold
radii shown in Table 4 break down
evenly with 11 at depths ≤880 m (mean
threshold radius of 8,473 m) and ten at
depths ≥2,560 m (mean threshold radius
of 5,040 m). Therefore, the overall mean
for all scenarios of 6,838 m was used for
estimating potential exposures for track
lines occurring in water depths of 880–
2,560 m.
Regarding marine mammal
occurrence, TGS considered both the
Roberts et al. (2016) density models as
well as the AMAPPS data. TGS stated
that there are aspects of the Roberts et
al. (2016) methodology that limit the
model outputs’ applicability to
estimating marine mammal exposures to
underwater sound and determined it
appropriate to develop their own
density estimates for certain species
using AMAPPS data.
As stated above, we believe the
density models described by Roberts et
al. (2016) provide the best available
information at the time of our
evaluation and recommend their use for
species other than those expected to be
extremely rare in a given area. However,
TGS used the most recent observational
data available in their alternative take
estimation process conducted for seven
of the affected species or groups. We
acknowledge their concerns regarding
use of predictive density models for
species with relatively few observations
in the survey area, e.g., that modelderived density estimates must be
applied cautiously on a species-byspecies basis with the recognition that
in some cases the out-of-bound
predictions could produce unrealistic
results (Becker et al., 2014). Further, use
of uniform (i.e., stratified) density
models assumes a given density over a
large geographic range which may
include areas where the species has
rarely or never been observed. For the
seven species or species groups that
TGS applied their alternative approach
to (described below), five are modeled
in whole or part through use of stratified
models. We also acknowledge (as do
Roberts et al. (2016)) that predicted
habitat may not be occupied at expected
densities or that models may not agree
in all cases with known occurrence
patterns, and that there is uncertainty
associated with predictive habitat
modeling (e.g., Becker et al., 2010;
Forney et al., 2012). We determined that
TGS’ alternative approach (for seven
species or species groups) is acceptable
and, importantly, we recognize that
there is no model or approach that is
always the most appropriate and that
there may be multiple approaches that
may be considered acceptable (e.g., Box,
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1979). Further detailed discussion on
these topics was provided in our Notice
of Proposed IHAs, and is not repeated
here.
In summary, TGS described the
following issues in support of their
development of an alternative approach
for certain species:
• There are very few sightings of
some species despite substantial survey
effort;
• The modeling approach
extrapolates based on habitat
associations and assumes some species’
occurrence in areas where they have
never been or were rarely documented
(despite substantial effort);
• In some cases, uniform density
models spread densities of species with
small sample sizes across large areas of
the EEZ without regard to habitat, and;
• The most recent NOAA shipboard
and aerial survey data (i.e., AMAPPS)
were not included in model
development.
As a result of their general concerns
regarding suitability of model outputs
for exposure estimation, TGS developed
a scheme related to the number of
observations in the dataset available to
Roberts et al. (2016) for use in
developing the density models.
Extremely rare species (i.e., less than
four sightings in the survey area) were
considered to have a very low
probability of encounter, and it was
assumed that the species might be
encountered once. Therefore, a single
group of the species was considered as
expected to be exposed to sound
exceeding the 160 dB rms harassment
criterion. We agree with this approach
for rarely occurring species and adopted
it for all applicants, as described below.
As described previously, marine
mammal abundance has traditionally
been estimated by applying distance
sampling methodology (Buckland et al.,
2001) to visual line-transect survey data.
Buckland et al. (2001) recommend a
minimum sample size of 60–80
sightings to provide reasonably robust
estimates of density and abundance to
fit the mathematical detection function
required for this estimation; smaller
sample sizes result in higher variance
and thus less confidence and less
accurate estimates. While we agree that
TGS’ approach is a reasonable one, we
also note that the Buckland et al. (2001)
recommendation that sample size
should generally be at least 60–80
should be considered as general
guidance but not an absolute rule.
Buckland et al. (2001) provide no
theoretical proof for it and, in fact, it has
not been followed as a rule in practice.
Miller and Thomas (2015) provide an
example where a detection function
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fitted to 30 sightings resulted in a
detection function with low bias.
NMFS’s line-transect abundance
estimates are in some cases based on
many fewer sightings, e.g., stock
assessments based on Palka (2012). For
species meeting the Buckland et al.
guideline within the survey area, TGS
used Roberts et al. (2016)’s model. For
species with fewer sightings (but with
greater than four sightings in the survey
area), TGS used what they refer to as
‘‘Line Transect Theory’’ in conjunction
with AMAPPS data to estimate species
density within the assumed 160 dB rms
zone of ensonification.
Nine species or species groups met
TGS’ requirement of having at least 60
sightings within the survey area in the
dataset available to Roberts et al. (2016):
Atlantic spotted dolphin, pilot whales,
striped dolphin, beaked whales,
bottlenose dolphin, Risso’s dolphin,
common dolphin, sperm whale, and
humpback whale. The steps involved in
the exposure estimation process for
these species was described in full in
our Notice of Proposed IHAs and is not
repeated here.
Seven species or species groups met
TGS’ criterion for conducting exposure
modeling, but did not have the
recommended 60 sightings in the survey
area: Minke whale, fin whale, Kogia
spp., harbor porpoise, pantropical
spotted dolphin, clymene dolphin, and
rough-toothed dolphin. For these
species, TGS did not feel use of the
density models was appropriate and
developed a method using the available
data instead (i.e., AMAPPS data as well
as data considered by Roberts et al.
(2016), excluding results of surveys
conducted entirely outside of an area
roughly coincident with the planned
survey area); species-specific rationale
is provided in section 6.3 of TGS’
application. Please see section 6.3 of
TGS’ application for further details
regarding the AMAPPS survey effort
considered by TGS. Table 6–1 in TGS’
application summarizes the AMAPPS
data available for consideration by the
authors. The steps involved in the
exposure estimation process for these
species was described in full in our
Notice of Proposed IHAs and is not
repeated here (see Table 6–4 in TGS’
application for numerical process
details).
TGS initially proposed use of a
mitigation source (i.e., 90-in3 airgun) for
line turns and transits not exceeding
three hours and produced exposure
estimates specific to use of the
mitigation source. As described in
‘‘Mitigation,’’ we do not allow use of the
mitigation source; therefore, exposure
estimates specific to use of a mitigation
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gun would not actually occur. In their
application, TGS provided exposure
estimates specific to use of the fullpower array and to use of the mitigation
gun for the seven species for which the
alternative approach was followed, but
not for the nine species whose exposure
estimates are based on the Roberts et al.
(2016) density models (for the latter
group, only a combined total was
provided). Therefore, in our Notice of
Proposed IHAs, we did not include
mitigation gun exposure estimates for
the former group but did for the latter
group, noting exposure estimates for
those nine species were slightly
overestimated. However, following
publication of our Notice of Proposed
IHAs, TGS provided a breakdown for
these species according to full-power
array versus mitigation source;
therefore, we have removed the
estimates associated with use of the
mitigation source for all species. Take
authorization numbers provided for
TGS (Table 6) reflect this appropriate
adjustment.
Western—Western’s approach to
estimating potential marine mammal
exposures to underwater sound was
identical to that described above for
TGS; therefore, we do not provide a
separate description for Western.
Western also initially proposed use of
a mitigation source for line turns and
transits not exceeding three hours and
produced exposure estimates specific to
use of the mitigation source. Like TGS,
Western’s application provided
information specific to use of the fullpower array versus the mitigation
source for the seven species for which
the alternative approach was followed,
but not for the nine species whose
exposure estimates are based on the
Roberts et al. (2016) density models (for
the latter group, only a combined total
was provided). However, unlike TGS,
Western did not provide additional
information following publication of our
Notice of Proposed IHAs. Therefore,
mitigation gun exposure estimates are
included in the total for the latter group,
and exposure estimates for those nine
species are slightly overestimated.
CGG—CGG used applicable results
from BOEM’s sound field modeling
exercise in conjunction with the outputs
of models described by Roberts et al.
(2016) to inform their estimates of likely
acoustic exposures. CGG’s exposure
modeling process was described in full
in our Notice of Proposed IHAs; please
see that document for more detail.
Considering only the BOEM modeling
sites that are in or near CGG’s survey
area provided a mean radial distance to
the 160 dB rms criterion of 6,751 m
(range 5,013–8,593 m). Taxon-specific
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model outputs, averaged over the sixmonth period planned for the survey
(i.e., July-December) where relevant,
were used with the assumed
ensonification zone to provide estimates
of marine mammal exposures to noise
above the 160 dB rms threshold. Similar
to other applicants, CGG performed an
interpolation analysis to estimate
density values for the portion of
planned survey area outside the EEZ.
North Atlantic Right Whale—As
described above, given the current
status of North Atlantic right whales, we
re-evaluated available information
subsequent to public review of our
proposed IHAs. Finding that significant
improvements were available to us, we
determined it appropriate to re-estimate
acoustic exposures specifically for right
whales using the updated models. To do
so, we relied on the sound field
modeling results provided in BOEM’s
2014 PEIS (see description above and
Appendix D in BOEM (2014a)), as was
previously done by TGS, CGG, and
Western in their IHA applications.
Using site- and season-specific radii to
the 160 dB rms threshold (95 percent
range, see Table 4 above or Table D–22
in BOEM (2014a)) and the total amount
of trackline planned by each company
within the acoustic modeling regions
specified in BOEM’s 2014 PEIS (see
Appendix E, Table E–5 and Figures E–
11 to E14 in BOEM (2014a)), we
calculated monthly, region-specific
ensonified areas for each company as if
their entire survey tracklines were
completed in each month. Then, using
the updated 2017 density model outputs
(Roberts et al., 2017), we calculated
average monthly regional right whale
densities, which were then multiplied
by the monthly ensonified areas.
Finally, these data were averaged
(annually or according to the planned
operating window where appropriate) to
estimate the average total exposure of
North Atlantic right whales. In this way,
we incorporated the seasonal variation
in density of right whales since we do
not know the exact distribution of
survey effort within each company’s
operating window.
Importantly, in these calculations we
took into account the time-area
restrictions specified in ‘‘Mitigation.’’
For the year-round closure areas, data
(i.e., ensonified areas and North Atlantic
right whale densities) were not used to
formulate exposure estimates since
surveys would be completely prohibited
within these areas. In the seasonal
restriction areas, only data from months
when the areas are open were used in
calculating the exposure estimates. The
final resulting exposure estimates then
are based on the best available
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information on North Atlantic right
whale densities within the action area
(Roberts et al., 2017), fully take into
account all time-area restrictions, and
are specific to each company’s
tracklines and planned operating
window (if specified). Take estimates
shown in Table 6 for North Atlantic
right whales reflect this analysis, and
replace those previously estimated
using different information and
specified in our Notice of Proposed
IHAs.
Time-Area Restrictions—Following
review of public comments, we
conducted an analysis of expected take
avoided due to implementation of the
time-area restrictions described in
‘‘Mitigation.’’ To do this, we took an
approach related to that previously
described for right whales. In brief, we
started with the existing take estimates
as described in our Notice of Proposed
IHAs and then calculated the take that
would be avoided due to the planned
restrictions. We then subtracted this
from the originally proposed take to get
our final take estimates. As described
below, we took a slightly different
approach for the sperm whale as
compared with other species in that we
accounted for the seasonal restriction of
Area #4 (the ‘‘Hatteras and North’’
restriction; see ‘‘Mitigation’’). We did
this because the area was designed in
part specifically to benefit sperm
whales, and because density model
outputs are provided at monthly
resolution for sperm whales, whereas
density model outputs are provided at
only annual resolution for beaked
whales and pilot whales (Area #4 was
also designed specifically to benefit
these species). Take avoided due to
seasonal restrictions, versus year-round
closures, cannot be calculated for
species for which only annual density
outputs are available. For those species
with monthly data availability but for
which the seasonal restriction was not
designed, we determined that the
analysis was unlikely to result in
meaningful changes to the take
estimates.
For sperm whales, we calculated the
monthly density within each year-round
closure area using the Roberts et al.
(2016) model outputs and calculated the
monthly ensonified area within each
year-round closure for each company
based on their planned tracklines and
the radii to the 160 dB rms threshold.
We then multiplied these monthly
numbers by each other to estimate the
monthly take avoided and, finally,
computed the annual average of these
avoided takes to estimate the overall
take that would be avoided due to the
year-round closures. For the seasonal
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restrictions, only Area #4 (the ‘‘Hatteras
and North’’ restriction; see
‘‘Mitigation’’) was accounted for since it
is the only seasonal restriction designed
specifically to protect sperm whales.
While we considered accounting for the
North Atlantic right whale seasonal
restriction, we opted not to since it
primarily protects shallower waters
where sperm whales are less likely to be
found, and the added complication of
incorporating the restriction was
unlikely to result in meaningful changes
to the overall take estimates for sperm
whales. To account for Area #4, we
calculated the change in take due to the
restriction in a similar fashion to the
year-round closures above, except that
instead of calculating the change in take
based on an annual average, we
calculated the difference between the
average take for when the area is open
and when the area is closed in order to
calculate the overall change in take due
to restricting surveys within this area.
As before, for these calculations we took
into account specific survey timing
where relevant but otherwise assumed
the surveys could happen at any time of
the year. The combined year-round and
seasonal avoided takes were then
subtracted from the originally proposed
take authorizations described in our
Notice of Proposed IHAs to calculate the
final take estimates for sperm whales.
For other species, a simpler approach
was taken. First, we did not account for
any seasonal restrictions, either because
sufficient data is not available or
because the seasonal restrictions’ benefit
in protecting species for which they
were not specifically designed is
unclear. Second, we did not recalculate
density estimates specifically within the
year-round closures, but instead relied
on density estimates derived from the
Roberts et al. (2016) model outputs for
each acoustic modeling region used in
BOEM’s 2014 PEIS. Using these density
estimates, we then followed the same
procedure detailed above for sperm
whales (multiplied monthly or seasonal
densities by monthly or seasonal
ensonified area, and compute annual or
operating window average) to estimate
the take that would be avoided due to
the year-round closures. These avoided
takes were then subtracted from the
originally proposed take authorizations
described in our Notice of Proposed
IHAs to calculate the final take
estimates.
Level A Harassment
All requests for IHAs described herein
were received prior to NMFS’s original
2016 technical guidance and, therefore,
did not reflect consideration of the
currently best available information
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regarding the potential for auditory
injury. In our Notice of Proposed IHAs,
we described a process by which we
estimated expected takes by Level A
harassment in reflection of both NMFS’s
technical guidance and the specific
survey characteristics (i.e., actual linekms and specific airgun arrays planned
for use) using modeled auditory injury
exposure results found in BOEM’s 2014
PEIS. The PEIS results were based on
both the Southall et al. (2007) guidance
(a precursor to NMFS’s technical
guidance) and the historical 180-dB rms
criterion (which provides information
relevant to a comparison to the
likelihood of injurious exposure
resulting from peak pressure). That
process was described in our Notice of
Proposed IHAs and is not repeated here.
However, following review of public
comments, we determined it
appropriate to re-evaluate the analysis,
as described below.
In our Notice of Proposed IHAs, we
acknowledged that the Level A exposure
estimates provided therein—based on
adjustments made to the results
provided in BOEM’s PEIS—were a
rough approximation of potential
exposures, with multiple limitations in
reflection of the available information or
lack thereof. For example, specific
trackline locations planned by the
applicant companies may differ
somewhat from those considered in
BOEM’s PEIS, although it is likely that
all portions of the survey area are
considered in the PEIS analysis. More
importantly, the PEIS exposure
estimates were based on outputs of the
NODEs models (DoN, 2007) available for
BOEM’s analysis versus the density
models subsequently provided by
Roberts et al. (2016), which we believe
represent the best available information
for purposes of exposure estimation. In
addition, we noted that we did not
attempt to approximate the probability
of marine mammal aversion or to
incorporate the effects of mitigation on
the likelihood of Level A harassment.
Following review of public comments,
we reconsidered the likelihood of
potential auditory injury, specific to
each hearing group (i.e., low-frequency,
mid-frequency, and high-frequency),
and re-evaluated the specific Level A
harassment estimates presented in our
Notice of Proposed IHAs. Here, we
provide a revised analysis of likely takes
by Level A harassment.
Specifically, we determined that there
is a low likelihood of take by Level A
harassment for any species, and that this
likelihood is primarily influenced by
the specific hearing group. For mid- and
high-frequency cetaceans, potential
auditory injury would be expected to
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occur on the basis of instantaneous
exposure to peak pressure output from
an airgun array, leading to a relatively
straightforward consideration of the
Level A harassment zone as an areal
subset of the Level B harassment zone
and, therefore, takes by Level A
harassment as a subset of the previously
enumerated takes by Level B
harassment. However, for midfrequency cetaceans, additional
considerations of the small calculated
Level A harassment zone size in
conjunction with the properties of
sound fields produced by arrays in the
near field versus far field lead to a
logical conclusion that Level A
harassment is so unlikely for species in
this hearing group as to be discountable.
For low-frequency cetaceans,
consideration of the likely potential for
auditory injury is not straightforward, as
such exposure would occur on the basis
of the accumulation of energy output
over time by an airgun array. Additional
factors, such as the relative motion of
source and receiver and the
implementation of mitigation lead us to
conclude that a quantitative evaluation
of such potential, in light of the
available information, does not make
sense. Our evaluations for all three
hearing groups are detailed below.
As part of the exposure estimation
process described in our Notice of
Proposed IHAs, we calculated expected
injury zones specific to each applicant’s
array for each hearing group relative to
injury criteria for both the cSEL and
peak pressure metrics. The results of
this process, shown in Table 5, remain
valid and were used to inform the
revised estimates of take by Level A
harassment described herein. For the
cSEL metric, in order to incorporate the
technical guidance’s weighting
functions over an array’s full acoustic
band, we obtained unweighted
spectrum data (modeled in 1 Hz bands)
for a reasonably equivalent acoustic
source (i.e., a 36-airgun array with total
volume of 6,600 in3). Using these data,
we made adjustments (dB) to the
unweighted spectrum levels, by
frequency, according to the weighting
functions for each relevant marine
mammal hearing group. We then
converted these adjusted/weighted
spectrum levels to pressures
(micropascals) in order to integrate them
over the entire broadband spectrum,
resulting in broadband weighted source
levels by hearing group that could be
directly incorporated within NMFS’s
User Spreadsheet (i.e., override the
Spreadsheet’s more simple weighting
factor adjustment).
When NMFS (2016) was published, in
recognition of the fact that appropriate
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isopleth distances could be more
technically challenging to predict
because of the duration component in
the new thresholds, NMFS developed a
User Spreadsheet that includes tools to
help predict a simple isopleth that can
be used in conjunction with marine
mammal density to help predict
exposures. For mobile sources, such as
the surveys considered here, the User
Spreadsheet predicts the closest
distance at which a stationary animal
would not incur PTS if the sound source
traveled by the animal in a straight line
at a constant speed (the ‘‘safe distance’’
methodology discussed below). For
more information about the User
Spreadsheet, please see
www.fisheries.noaa.gov/national/
marine-mammal-protection/marinemammal-acoustic-technical-guidance.
Using the User Spreadsheet’s ‘‘safe
distance’’ methodology for mobile
sources (described by Sivle et al., 2014)
with the hearing group-specific
weighted source levels, and inputs
assuming spherical spreading
propagation, a source velocity of 4.5 kn,
shot intervals specified by the
applicants, and pulse duration of 100
ms, we then calculated potential radial
distances to auditory injury zones
relative to the cSEL metric. We also
calculated potential radial distances to
auditory injury zones on the basis of
maximum peak pressure using values
provided by the applicants (Table 1) and
assuming a simple model of spherical
spreading propagation. We note that our
Notice of Proposed IHAs contained an
error. On page 26254 of that notice, we
stated that the range of distances for
injury zones relative to the cSEL metric
was 80–4,766 m. The correct range is
80–951 m; results are shown in Table 5.
TABLE 5—ESTIMATED AUDITORY INJURY ZONES 1
Hearing group
Metric
Low-frequency ........................................................................
Mid-frequency .........................................................................
High-frequency .......................................................................
cSEL
peak
cSEL
peak
cSEL
peak
Estimated near-field 2 .............................................................
Spectrum
ION
757
224
0
63
1
1,585
417
TGS
951
79
0
22
8
562
233
Western
380
63
0
18
1
447
142
80
71
0
20
0
501
80
CGG
757
50
0
14
1
355
141
1 Radial
isopleth distances presented in meters.
discussion of ‘‘near-field’’ below.
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actual locations within these distances
(i.e., 14–63 m) of the array center where
the sound level exceeds 230 dB peak
SPL would not necessarily exist. In
general, Caldwell and Dragoset (2000)
suggest that the near-field for airgun
arrays is considered to extend out to
approximately 250 m.
In order to provide quantitative
support for this theoretical argument,
we calculated expected maximum
distances at which the near-field would
transition to the far-field (Table 5). For
a specific array one can estimate the
distance at which the near-field
transitions to the far-field by:
with the condition that D >> l, and
where D is the distance, L is the longest
dimension of the array, and l is the
wavelength of the signal (Lurton, 2002).
Given that l can be defined by:
where f is the frequency of the sound
signal and v is the speed of the sound
in the medium of interest, one can
rewrite the equation for D as:
and calculate D directly given a
particular frequency and known speed
of sound (here assumed to be 1,500
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these interactions to scale to predictions
of real-world exposures given a
sufficient number of predicted 24-hr
survey days in confluence with
sufficiently high predicted real-world
animal densities—i.e., the modeling
process that resulted in the predicted
exposure estimates for mid-frequency
cetaceans in BOEM’s PEIS—this is not
a realistic outcome. The source level of
the array is a theoretical definition
assuming a point source and
measurement in the far-field of the
source (MacGillivray, 2006). As
described by Caldwell and Dragoset
(2000), an array is not a point source,
but one that spans a small area. In the
far-field, individual elements in arrays
will effectively work as one source
because individual pressure peaks will
have coalesced into one relatively broad
pulse. The array can then be considered
a ‘‘point source.’’ For distances within
the near-field, i.e., approximately 2–3
times the array dimensions, pressure
peaks from individual elements do not
arrive simultaneously because the
observation point is not equidistant
from each element. The effect is
destructive interference of the outputs
of each element, so that peak pressures
in the near-field will be significantly
lower than the output of the largest
individual element. Here, the 230 dB
peak isopleth distances would in all
cases be expected to be within the nearfield of the arrays where the definition
of source level breaks down. Therefore,
EN07DE18.004
Based on our analysis of expected
injury zones (Table 5), accumulation of
energy is considered to be the
predominant source of potential
auditory injury for low-frequency
cetaceans in all cases, while
instantaneous exposure to peak pressure
received levels is considered to be the
predominant source of potential injury
for both mid- and high-frequency
cetaceans in all cases. Please note that
discussion in this section and estimates
of take by Level A harassment provided
in Table 6 for Spectrum relate to
Spectrum’s original survey plan. Please
see ‘‘Spectrum Survey Plan
Modification’’ for additional discussion
of Level A harassment reflecting
Spectrum’s modified survey plan.
Mid-Frequency Cetaceans—For all
mid-frequency cetaceans, following reevaluation of the available scientific
literature regarding the auditory
sensitivity of mid-frequency cetaceans
and the properties of airgun array sound
fields, we do not expect any reasonable
potential for Level A harassment to
occur. For these species, the only
potential injury zones (for all
applicants) would be based on the peak
pressure metric (Table 5). However, the
estimated zone sizes for the 230 dB peak
threshold for mid-frequency cetaceans
range from only 14 m to 63 m. While in
a theoretical modeling scenario it is
possible for animats to engage with such
small assumed zones around a notional
point source and, subsequently, for
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meters per second in water, although
this varies with environmental
conditions).
To determine the closest distance to
the arrays at which the source level
predictions in Table 1 are valid (i.e.,
maximum extent of the near-field), we
calculated D based on an assumed
frequency of 1 kHz. A frequency of 1
kHz is commonly used in near-field/farfield calculations for airgun arrays
(Zykov and Carr, 2014; MacGillivray,
2006; NSF and USGS, 2011), and based
on representative airgun spectrum data
and field measurements of an airgun
array used on the R/V Marcus G.
Langseth, nearly all (greater than 95
percent) of the energy from airgun
arrays is below 1 kHz (Tolstoy et al.,
2009). Thus, using 1 kHz as the upper
cut-off for calculating the maximum
extent of the near-field should
reasonably represent the near-field
extent in field conditions.
If the largest distance to the peak
sound pressure level threshold was
equal to or less than the longest
dimension of the array (i.e., under the
array), or within the near-field, then
received levels that meet or exceed the
threshold in most cases are not expected
to occur. This is because within the
near-field and within the dimensions of
the array, the source levels specified in
Table 1 are overestimated and not
applicable. In fact, until one reaches a
distance of approximately three or four
times the near-field distance the average
intensity of sound at any given distance
from the array is still less than that
based on calculations that assume a
directional point source (Lurton, 2002).
For example, an airgun array used on
the R/V Marcus G. Langseth has an
approximate diagonal of 29 m, resulting
in a near-field distance of 140 m at 1
kHz (NSF and USGS, 2011). Field
measurements of this array indicate that
the source behaves like multiple
discrete sources, rather than a
directional point source, beginning at
approximately 400 m (deep site) to 1 km
(shallow site) from the center of the
array (Tolstoy et al., 2009), distances
that are actually greater than four times
the calculated 140-m near-field
distance. Within these distances, the
recorded received levels were always
lower than would be predicted based on
calculations that assume a directional
point source, and increasingly so as one
moves closer towards the array (Tolstoy
et al., 2009). Given this, relying on the
calculated distances (Table 5) as the
distances at which we expect to be in
the near-field is a conservative approach
since even beyond this distance the
acoustic modeling still overestimates
the actual received level.
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Within the near-field, in order to
explicitly evaluate the likelihood of
exceeding any particular acoustic
threshold, one would need to consider
the exact position of the animal, its
relationship to individual array
elements, and how the individual
acoustic sources propagate and their
acoustic fields interact. Given that
within the near-field and dimensions of
the array source levels would be below
those in Table 1, we believe exceedance
of the peak pressure threshold would
only be possible under highly unlikely
circumstances.
Therefore, we expect the potential for
Level A harassment of mid-frequency
cetaceans to be de minimis, even before
the likely moderating effects of aversion
and/or other compensatory behaviors
(e.g., Nachtigall et al., 2018) are
considered. We do not believe that
Level A harassment is a likely outcome
for any mid-frequency cetacean and do
not authorize any Level A harassment
for these species.
Low-Frequency Cetaceans—For lowfrequency cetaceans, we previously
adjusted the BOEM PEIS estimates of
potential Level A harassment to account
for NMFS’s technical acoustic guidance,
as described in our Notice of Proposed
IHAs. This process resulted in few
estimated Level A harassment exposures
for low-frequency cetaceans, i.e., 2–22
such exposures for humpback whales
and 0–1 such exposures for minke
whales, depending on array specifics,
and zero exposures for right whales and
fin whales (see Table 11 in our Notice
of Proposed IHAs). The potential injury
zones are relatively large for lowfrequency cetaceans (up to 951 m; Table
5); therefore, we expect that some Level
A harassment may occur for the most
commonly occurring low-frequency
cetacean species (i.e., humpback, fin,
and minke whales). However, we also
note that injury on the basis of
accumulation of energy is not a
straightforward consideration of
calculated zone size, as is consideration
of injury on the basis of instantaneous
peak pressure exposure. For example,
observation of a whale at the distance
calculated as being the ‘‘injury zone’’
using the cSEL criterion does not
necessarily mean that the animal has in
fact incurred auditory injury. Rather, the
animal would have to be at the
calculated distance (or closer) as the
mobile source approaches, passes, and
recedes from the exposed animal, being
exposed to and accumulating energy
from airgun pulses the entire time, as is
implied by the name of the ‘‘safe
distance’’ methodology by which such
zone distances are calculated.
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Therefore, while we do believe that
some limited Level A harassment of
low-frequency cetaceans is likely
unavoidable, despite the required
mitigation measures (including rampup, shutdown upon detection within a
500-m exclusion zone for most
mysticetes and shutdown upon
detection of North Atlantic right whales
within an expanded 1.5-km exclusion
zone; see ‘‘Mitigation’’), we do not
believe that the process followed in
estimating potential Level A harassment
in our Notice of Proposed IHAs is the
most appropriate method. Further, upon
re-evaluation of the results of that
process, we do not have confidence in
those results, which suggest that Level
A harassment is likely for humpback
whales but not for fin whales. Upon
reconsideration of the available
information, we note that the original
information from BOEM’s PEIS includes
prediction of zero incidents of Level A
harassment for fin whales while
predicting non-zero results for all other
mysticete species (see Table E–4 in
BOEM (2014a))—a puzzling result that
underlies the lack of predicted Level A
harassment for fin whales in our Notice
of Proposed IHAs. Therefore, we apply
a simplified approach intended to
acknowledge that there would likely be
some minimal, yet difficult to accurately
quantify, Level A harassment of certain
mysticete species. As a result of the
planned mitigation, including a
seasonal restriction (or alternate
methods of equivalent impact
avoidance) and an expanded right whale
exclusion zone of 1.5 km (intended to
practicably avoid or minimize
interaction with North Atlantic right
whales; see ‘‘Mitigation’’), we do not
expect any reasonable potential for
Level A harassment of North Atlantic
right whales (consistent with the
predictions of our original analysis).
Any likely potential for the occurrence
of Level A harassment is further
minimized by likely aversion. For
example, Ellison et al. (2016)
demonstrated that animal movement
models where no aversion probability
was used overestimated the potential for
high levels of exposure required for PTS
by about five times.
In order to account for the minimal
likelihood of Level A harassment
occurring for low-frequency cetaceans,
we assume that in most cases during the
course of conducting the survey at least
one group of each species could incur
auditory injury for all applicants other
than Western. (As shown in Table 5, the
calculated injury zone for Western is
only 80 m. It is extremely unlikely that
injury could occur given such a small
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calculated zone, especially in context of
a required 500-m exclusion zone.) We
acknowledge that application of group
size to estimation of take is more
appropriate for take resulting from
instantaneous exposure than it is for
take resulting from the accumulation of
energy, as any given group may disperse
to some degree in a way that could lead
to differing accumulation among
individuals of the group. However,
given the low likelihood of take by
Level A harassment, small group sizes
typical of mysticetes, and the likelihood
that these individuals will remain
within close distance of one another
during the exposure, we believe that use
of group size is appropriate in this
context.
For applicants other than Western, we
consider both the size of the calculated
potential injury zone and the total
amount of planned survey effort.
Spectrum, CGG, and ION have larger
calculated potential injury zones, i.e.,
larger than the required 500-m
exclusion zone (Table 5). However, ION
has significantly less total survey effort
(approximately half of what is planned
by Spectrum and CGG; Table 1). TGS
has a significantly smaller calculated
injury zone, i.e., smaller than the
required 500-m exclusion zone.
However, at 380 m, the zone is
sufficiently large that a whale could
potentially occur within the zone
without being observed in time to
implement shutdown, and TGS’s
planned survey effort is substantially
larger (approximately twice as large as
that planned by Spectrum and CGG).
Therefore, TGS’ lower likelihood of
causing injury is offset to some degree
by their substantially greater survey
effort. Finally, on the basis of expected
taking by Level B harassment (Table 6),
we see that the location and timing of
CGG’s planned survey effort results in
significantly less potential interaction
with humpback whales than for
Spectrum and TGS.
In summary, we conclude there is
sufficiently reasonable potential for
Level A harassment (even considering
the likely effects of aversion) that it is
appropriate to authorize take by Level A
harassment for a minimum of one
average size group of each relevant
species (i.e., humpback, minke, and fin
whales) for Spectrum, TGS, ION, and
CGG. For Spectrum, in consideration of
the calculated injury zone and level of
planned effort, we increase this to two
groups of each relevant species. For
TGS, in consideration of the level of
planned survey effort and despite the
smaller calculated injury zone, we also
increase this to two groups of each
relevant species. For CGG, in
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consideration of the calculated injury
zone and level of planned effort, we
increase this to two groups for minke
whales and fin whales only, given the
lower potential for interaction with
humpback whales. For ION, given the
lower level of planned survey effort, we
maintain the take authorization at one
group of each relevant species. As a
point of reference, we note that BOEM’s
PEIS analysis of potential takes by Level
A harassment estimated that no more
than 5.9 humpback whales could
experience auditory injury in any given
year for all surveys combined, despite a
greater amount of assumed activity.
Estimates were much less for all other
species (see Table E–4 of BOEM
(2014a)). As noted above, please see
‘‘Spectrum Survey Plan Modification’’
for additional discussion of Level A
harassment reflecting Spectrum’s
modified survey plan, including Table
17, providing revised (and authorized)
levels of take by Level A harassment for
Spectrum.
Average group size was determined
by considering observational data from
AMAPPS survey effort (e.g., NMFS,
2010a, 2011, 2012, 2013a, 2014, 2015a).
Average group sizes were as follows: Fin
whale, 1.3 whales; humpback whale, 1.4
whales; minke whale, 1.2 whales.
Therefore, we assume an average group
size of two whales for each species.
These take authorizations, which are
subtracted from the estimates for take by
Level B harassment to avoid doublecounting, are shown in Table 6.
High-Frequency Cetaceans—For highfrequency cetaceans (i.e., Kogia spp. and
harbor porpoise), injury zones are based
on instantaneous exposure to peak
pressure and are larger than the
expected near-field in all cases (i.e.,
355–1,585 m). Therefore, we assume
that Level A harassment is likely for
some individuals of these species. In
order to avoid consistency issues that
may result when estimates of Level A
harassment are based off of the results
of a separate analysis that was founded
in part on use of different density
inputs, as was the case for the estimates
of Level A harassment described in our
Notice of Proposed IHAs, we simplified
the analysis through use of the existing
estimates of Level B harassment for each
applicant. Under the assumption that
some of these estimated exposures
would in fact result in Level A
harassment versus Level B harassment,
we used applicant-specific calculated
Level A and Level B harassment zones
to generate estimates of the portion of
estimated Level B harassment incidents
that would be expected to be Level A
harassment instead. For example, radial
isopleth distances for Spectrum’s
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63339
calculated harassment zones are 1,585
m for Level A harassment and a mean
of 9,775 m for Level B harassment,
which we use to calculate relative area.
On this basis, we assume that
approximately 2.6 percent of estimated
Level B harassment incidents would
potentially be Level A harassment
instead (for Spectrum). These final
estimates, shown in Table 6, were then
subtracted from the total take by Level
B harassment. As noted for lowfrequency cetaceans, we recognize that
the effects of aversion would likely
reduce these already low levels of Level
A harassment.
We recognize that the Level A
exposure estimates provided here are a
rough approximation of actual
exposures; however, our intention is to
use the information available to us, in
reflection of available science regarding
the potential for auditory injury, to
acknowledge the potential for such
outcomes in a way that is a reasonable
approximation. Our revised analysis of
potential Level A harassment, as
reflected in Table 6, accomplishes this
goal. As described in our Notice of
Proposed IHAs, we note here that four
of the five applicant companies
(excepting Spectrum) declined to
request authorization of take by Level A
harassment. These four applicants
claim, in summary, that injurious
exposures will not occur largely due to
the effectiveness of planned mitigation.
While we agree that Level A harassment
is unlikely for mid-frequency cetaceans,
and that only limited injurious exposure
is likely for low-frequency cetaceans, we
do not find this assertion persuasive in
all cases. Therefore, we are authorizing
limited take by Level A harassment, as
displayed in Table 6.
Rare Species
Certain species potentially present in
the survey areas are expected to be
encountered only extremely rarely, if at
all. Although Roberts et al. (2016)
provide density models for these species
(with the exception of the pygmy killer
whale), due to the small numbers of
sightings that underlie these models’
predictions we believe it appropriate to
account for the small likelihood that
these species would be encountered by
assuming that these species might be
encountered once by a given survey,
and that Level A harassment would not
occur for these species. With the
exception of the northern bottlenose
whale, none of these species should be
considered cryptic (i.e., difficult to
observe when present) versus rare (i.e.,
not likely to be present). Average group
size was determined by considering
known sightings in the western North
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Atlantic (CETAP, 1982; Hansen et al,
1994; NMFS, 2010a, 2011, 2012, 2013a,
2014, 2015a; Waring et al., 2007, 2015).
We provided discussion for each of
these species in our Notice of Proposed
IHAs, and do not repeat the discussion
here. For each of these species—sei,
Bryde’s, and blue whales; the northern
bottlenose whale; killer whale, false
killer whale, pygmy killer whale, and
melon-headed whale; and spinner,
Fraser’s, and Atlantic white-sided
dolphins—we authorize take equivalent
to one group of each species per
applicant (Table 6).
Table 6 provides the authorized
numbers of take by Level A and Level
B harassment for each applicant. The
numbers of authorized take reflect the
expected exposure numbers provided in
Table 10 of our Notice of Proposed
IHAs, as derived by various methods
described above, and additionally
include take numbers for rare species
that reflect the approach described
above for average group size. In
summary, the exposure estimates
provided in Table 10 of our Notice of
Proposed IHAs have been changed in
reflection of the following: (1) Revised
exposure estimates for North Atlantic
right whales using Roberts et al. (2017);
(2) removed exposure estimates specific
to use of the disallowed mitigation
source as necessary for certain species
(TGS only); (3) removed estimated take
avoided as a result of implementation of
planned time-area restrictions; and (4)
revised analysis of potential Level A
harassment.
As described previously, for most
species these estimated exposure levels
apply to a generic western North
Atlantic stock defined by NMFS for
management purposes. For the
humpback and sei whale, any takes are
assumed to occur to individuals of the
species occurring in the specific
geographic region (which may or may
not be individuals from the Gulf of
Maine and Nova Scotia stocks,
respectively). For bottlenose dolphins,
NMFS defines an offshore stock and
multiple coastal stocks of dolphins, and
we are not able to quantitatively
determine the extent to which the
estimated exposures may accrue to the
oceanic versus various coastal stocks.
However, because of the spatial
distribution of planned survey effort
and our prescribed mitigation, we
assume that almost all incidents of take
for bottlenose dolphins would accrue to
the offshore stock.
TABLE 6—NUMBERS OF POTENTIAL INSTANCES OF INCIDENTAL TAKE AUTHORIZED
Spectrum 1
TGS
ION
Western
CGG
Common name
Level A
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North Atlantic
right whale .....
Humpback whale
Minke whale ......
Bryde’s whale ....
Sei whale ...........
Fin whale ...........
Blue whale .........
Sperm whale .....
Kogia spp. .........
Beaked whales ..
Northern
bottlenose
whale .............
Rough-toothed
dolphin ...........
Common
bottlenose dolphin ................
Clymene dolphin
Atlantic spotted
dolphin ...........
Pantropical spotted dolphin .....
Spinner dolphin
Striped dolphin ..
Common dolphin
Fraser’s dolphin
Atlantic whitesided dolphin
Risso’s dolphin ..
Melon-headed
whale .............
Pygmy killer
whale .............
False killer whale
Killer whale ........
Pilot whales .......
Harbor porpoise
Level B
Level A
Level B
Level A
Level B
Level A
Level B
Level A
Level B
0
4
4
0
0
4
0
0
5
0
6
41
419
2
2
333
1
1,077
200
3,357
0
4
4
0
0
4
0
0
5
0
9
56
208
2
2
1,140
1
3,579
1,216
12,072
0
2
2
0
0
2
0
0
22
0
2
5
10
2
2
3
1
16
28
490
0
0
0
0
0
0
0
0
3
0
4
49
100
2
2
537
1
1,941
569
4,960
0
2
4
0
0
4
0
0
22
0
2
5
124
2
2
45
1
1,304
238
3,511
0
4
0
4
0
4
0
4
0
4
0
201
0
261
0
1 14
0
123
0
177
0
0
37,562
6,459
0
0
40,595
821
0
0
2,599
252
0
0
23,600
391
0
0
9,063
6,382
0
16,926
0
41,222
0
568
0
18,724
0
6,596
0
0
0
0
0
1,632
91
8,022
11,087
204
0
0
0
0
0
1,470
91
23,418
52,728
204
0
0
0
0
0
78
91
162
372
204
0
0
0
0
0
690
91
8,845
20,683
204
0
0
0
0
0
1,566
91
6,328
6,026
204
0
0
48
755
0
0
48
3,241
0
0
48
90
0
0
48
1,608
0
0
48
809
0
50
0
50
0
50
0
50
0
50
0
0
0
0
16
6
28
7
2,765
611
0
0
0
0
23
6
28
7
8,902
322
0
0
0
0
23
6
28
7
199
18
0
0
0
0
23
6
28
7
4,682
152
0
0
0
0
23
6
28
7
1,964
27
1 Take numbers provided for Spectrum reflect Spectrum’s original survey plan and are retained here in reference to the negligible impact and small numbers analyses provided later in this document for Spectrum. For revised (and authorized) take numbers for Spectrum reflecting their modified survey plan, please see ‘‘Spectrum Survey Plan Modification.’’
2 Exposure estimate increased to account for average group size observed during AMAPPS survey effort. For ION, estimated Level A harassment of Kogia spp.
and harbor porpoise was zero and, for CGG, estimated Level A harassment of harbor porpoise was zero. We assume as a precaution that one group (as estimated
from AMAPPS data) may incur Level A harassment.
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Mitigation
Under section 101(a)(5)(D) of the
MMPA, NMFS must set forth the
‘‘permissible methods of taking
pursuant to such activity, and other
means of effecting the least practicable
impact on such species or stock and its
habitat, paying particular attention to
rookeries, mating grounds, and areas of
similar significance, and on the
availability of such species or stock for
taking for certain subsistence uses.’’
(While section 101(a)(5)(D) refers to
‘‘least practicable impact,’’ we hereafter
use the term ‘‘least practicable adverse
impact,’’ the term as it appears in
section 101(a)(5)(A). Given the
provision in which the language
appears, and its similarity to the parallel
provision in section 101(a)(5)(A), we
believe that ‘‘least practicable impact’’
in section 101(a)(5)(D) similarly is
referring to the requirement to prescribe
the means of effecting the least
practicable adverse impact, and we
interpret the term in that manner.)
Consideration of the availability of
marine mammal species or stocks for
taking for subsistence uses pertains only
to Alaska, and is therefore not relevant
here. NMFS does not have a regulatory
definition for ‘‘least practicable adverse
impact.’’
In Conservation Council for Hawaii v.
National Marine Fisheries Service, 97 F.
Supp.3d 1210, 1229 (D. Haw. 2015), the
Court stated that NMFS ‘‘appear[s] to
think [it] satisf[ies] the statutory ‘least
practicable adverse impact’ requirement
with a ‘negligible impact’ finding.’’
More recently, expressing similar
concerns in a challenge to an incidental
take rule for U.S. Navy Operation of
Surveillance Towed Array Sensor
System Low Frequency Active Sonar
(SURTASS LFA) (77 FR 50290), the
Ninth Circuit Court of Appeals in
Natural Resources Defense Council
(NRDC) v. Pritzker, 828 F.3d 1125, 1134
(9th Cir. 2016), stated, ‘‘[c]ompliance
with the ‘negligible impact’ requirement
does not mean there [is] compliance
with the ‘least practicable adverse
impact’ standard.’’ As the Ninth Circuit
noted in its opinion, however, the Court
was interpreting the statute without the
benefit of NMFS’s formal interpretation.
We state here explicitly that NMFS is in
full agreement that the ‘‘negligible
impact’’ and ‘‘least practicable adverse
impact’’ requirements are distinct, even
though both statutory standards refer to
species and stocks. With that in mind,
we provide further explanation of our
interpretation of least practicable
adverse impact, and explain what
distinguishes it from the negligible
impact standard. This discussion is
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consistent with, and expands upon,
previous rules we have issued (such as
the Navy Gulf of Alaska rule (82 FR
19530; April 27, 2017)).
Before NMFS can issue an incidental
take authorization under sections
101(a)(5)(A) or (D) of the MMPA, it must
make a finding that the taking will have
a ‘‘negligible impact’’ on the affected
‘‘species or stocks’’ of marine mammals.
NMFS’s and U.S. Fish and Wildlife
Service’s implementing regulations for
section 101(a)(5) both define ‘‘negligible
impact’’ as an impact resulting from the
specified activity that cannot be
reasonably expected to, and is not
reasonably likely to, adversely affect the
species or stock through effects on
annual rates of recruitment or survival
(50 CFR 216.103 and 50 CFR 18.27(c)).
Recruitment (i.e., reproduction) and
survival rates are used to determine
population growth rates 1 and, therefore
are considered in evaluating population
level impacts.
Not every population-level impact
violates the negligible impact
requirement. The negligible impact
standard does not require a finding that
the anticipated take will have ‘‘no
effect’’ on population numbers or
growth rates. The statutory standard
does not require that the same recovery
rate be maintained, rather that no
significant effect on annual rates of
recruitment or survival occurs. The key
factor is the significance of the level of
impact on rates of recruitment or
survival. See 54 FR 40338, 40341–42
(September 29, 1989).
While some level of impact on
population numbers or growth rates of
a species or stock may occur and still
satisfy the negligible impact
requirement—even without
consideration of mitigation—the least
practicable adverse impact provision
separately requires NMFS to prescribe
means of effecting the least practicable
adverse impact on such species or stock
and its habitat, paying particular
attention to rookeries, mating grounds,
and areas of similar significance. 50 CFR
216.102(b). These are typically
identified as mitigation measures.2
The negligible impact and least
practicable adverse impact standards in
the MMPA both call for evaluation at
the level of the ‘‘species or stock.’’ The
MMPA does not define the term
‘‘species.’’ However, Merriam-Webster
Dictionary defines ‘‘species’’ to include
‘‘related organisms or populations
1A
growth rate can be positive, negative, or flat.
purposes of this discussion we omit
reference to the language in the standard for least
practicable adverse impact that says we also must
mitigate for subsistence impacts because they are
not at issue in these actions.
2 For
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potentially capable of interbreeding.’’
See www.merriam-webster.com/
dictionary/species (emphasis added).
The MMPA defines ‘‘stock’’ as a group
of marine mammals of the same species
or smaller taxa in a common spatial
arrangement that interbreed when
mature. 16 U.S.C. 1362(11). The
definition of ‘‘population’’ is ‘‘a group of
interbreeding organisms that represents
the level of organization at which
speciation begins.’’ www.merriamwebster.com/dictionary/population. The
definition of ‘‘population’’ is strikingly
similar to the MMPA’s definition of
‘‘stock,’’ with both involving groups of
individuals that belong to the same
species and located in a manner that
allows for interbreeding. In fact, the
term ‘‘stock’’ in the MMPA is
interchangeable with the statutory term
‘‘population stock.’’ 16 U.S.C. 1362(11).
Thus, the MMPA terms ‘‘species’’ and
‘‘stock’’ both relate to populations, and
it is therefore appropriate to view both
the negligible impact standard and the
least practicable adverse impact
standard, both of which call for
evaluation at the level of the species or
stock, as having a population-level
focus.
This interpretation is consistent with
Congress’s statutory findings for
enacting the MMPA, nearly all of which
are most applicable at the species or
stock (i.e., population) level. See 16
U.S.C. 1361 (finding that it is species
and population stocks that are or may be
in danger of extinction or depletion; that
it is species and population stocks that
should not diminish beyond being
significant functioning elements of their
ecosystems; and that it is species and
population stocks that should not be
permitted to diminish below their
optimum sustainable population level).
Annual rates of recruitment (i.e.,
reproduction) and survival are the key
biological metrics used in the evaluation
of population-level impacts, and
accordingly these same metrics are also
used in the evaluation of population
level impacts for the least practicable
adverse impact standard.
Recognizing this common focus of the
least practicable adverse impact and
negligible impact provisions on the
‘‘species or stock’’ does not mean we
conflate the two standards; despite some
common statutory language, we
recognize the two provisions are
different and have different functions.
First, a negligible impact finding is
required before NMFS can issue an
incidental take authorization. Although
it is acceptable to use the mitigation
measures to reach a negligible impact
finding (see 50 CFR 216.104(c)), no
amount of mitigation can enable NMFS
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to issue an incidental take authorization
for an activity that still would not meet
the negligible impact standard.
Moreover, even where NMFS can reach
a negligible impact finding—which we
emphasize does allow for the possibility
of some ‘‘negligible’’ population-level
impact—the agency must still prescribe
measures that will effect the least
practicable amount of adverse impact
upon the affected species or stock.
Section 101(a)(5)(D)(ii)(I) (like section
101(a)(5)(A)(i)(II)) requires NMFS to
issue, in conjunction with its
authorization, binding—and
enforceable—restrictions setting forth
how the activity must be conducted,
thus ensuring the activity has the ‘‘least
practicable adverse impact’’ on the
affected species or stocks. In situations
where mitigation is specifically needed
to reach a negligible impact
determination, section 101(a)(5)(D)(ii)(I)
also provides a mechanism for ensuring
compliance with the ‘‘negligible
impact’’ requirement. Finally, we
reiterate that the least practicable
adverse impact standard also requires
consideration of measures for marine
mammal habitat, with particular
attention to rookeries, mating grounds,
and other areas of similar significance,
and for subsistence impacts; whereas
the negligible impact standard is
concerned solely with conclusions
about the impact of an activity on
annual rates of recruitment and
survival.3
In NRDC v. Pritzker, the Court stated,
‘‘[t]he statute is properly read to mean
that even if population levels are not
threatened significantly, still the agency
must adopt mitigation measures aimed
at protecting marine mammals to the
greatest extent practicable in light of
military readiness needs.’’ Id. at 1134
(emphases added). This statement is
consistent with our understanding
stated above that even when the effects
of an action satisfy the negligible impact
standard (i.e., in the Court’s words,
‘‘population levels are not threatened
significantly’’), still the agency must
prescribe mitigation under the least
practicable adverse impact standard.
However, as the statute indicates, the
focus of both standards is ultimately the
impact on the affected ‘‘species or
stock,’’ and not solely focused on or
directed at the impact on individual
marine mammals.
We have carefully reviewed and
considered the Ninth Circuit’s opinion
in NRDC v. Pritzker in its entirety.
While the Court’s reference to ‘‘marine
3 Mitigation may also be appropriate to ensure
compliance with the ‘‘small numbers’’ language in
MMPA sections 101(a)(5)(A) and (D).
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mammals’’ rather than ‘‘marine mammal
species or stocks’’ in the italicized
language above might be construed as a
holding that the least practicable
adverse impact standard applies at the
individual ‘‘marine mammal’’ level, i.e.,
that NMFS must require mitigation to
minimize impacts to each individual
marine mammal unless impracticable,
we believe such an interpretation
reflects an incomplete appreciation of
the Court’s holding. In our view, the
opinion as a whole turned on the
Court’s determination that NMFS had
not given separate and independent
meaning to the least practicable adverse
impact standard apart from the
negligible impact standard, and further,
that the Court’s use of the term ‘‘marine
mammals’’ was not addressing the
question of whether the standard
applies to individual animals as
opposed to the species or stock as a
whole. We recognize that while
consideration of mitigation can play a
role in a negligible impact
determination, consideration of
mitigation measures extends beyond
that analysis. In evaluating what
mitigation measures are appropriate,
NMFS considers the potential impacts
of the specified activity, the availability
of measures to minimize those potential
impacts, and the practicability of
implementing those measures, as we
describe below.
Given the NRDC v. Pritzker decision,
we discuss here how we determine
whether a measure or set of measures
meets the ‘‘least practicable adverse
impact’’ standard. Our separate analysis
of whether the take anticipated to result
from applicants’ activities satisfies the
‘‘negligible impact’’ standard appears in
the section ‘‘Negligible Impact Analyses
and Determinations’’ below.
Our evaluation of potential mitigation
measures includes consideration of two
primary factors:
(1) The manner in which, and the
degree to which, implementation of the
potential measure(s) is expected to
reduce adverse impacts to marine
mammal species or stocks, their habitat,
and their availability for subsistence
uses (when relevant). This analysis
considers such things as the nature of
the potential adverse impact (such as
likelihood, scope, and range), the
likelihood that the measure will be
effective if implemented, and the
likelihood of successful
implementation.
(2) The practicability of the measure
for applicant implementation.
Practicability of implementation may
consider such things as cost, impact on
operations, personnel safety, and
practicality of implementation.
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While the language of the least
practicable adverse impact standard
calls for minimizing impacts to affected
species or stocks, we recognize that the
reduction of impacts to those species or
stocks accrues through the application
of mitigation measures that limit
impacts to individual animals.
Accordingly, NMFS’s analysis focuses
on measures designed to avoid or
minimize impacts on marine mammals
from activities that are likely to increase
the probability or severity of
population-level effects.
While complete information on
impacts to species or stocks from a
specified activity is not available for
every activity type, and additional
information would help NMFS better
understand how specific disturbance
events affect the fitness of individuals of
certain species, there have been
significant improvements in
understanding the process by which
disturbance effects are translated to the
population. With recent scientific
advancements (both marine mammal
energetic research and the development
of energetic frameworks), the relative
likelihood or degree of impacts on
species or stocks may typically be
predicted given a detailed
understanding of the activity, the
environment, and the affected species or
stocks. This same information is used in
the development of mitigation measures
and helps us understand how mitigation
measures contribute to lessening effects
to species or stocks. We also
acknowledge that there is always the
potential that new information, or a new
recommendation that we had not
previously considered, becomes
available and necessitates re-evaluation
of mitigation measures (which may be
addressed through adaptive
management) to see if further reductions
of population impacts are possible and
practicable.
In the evaluation of specific measures,
the details of the specified activity will
necessarily inform each of the two
primary factors discussed above
(expected reduction of impacts and
practicability), and will be carefully
considered to determine the types of
mitigation that are appropriate under
the least practicable adverse impact
standard. Analysis of how a potential
mitigation measure may reduce adverse
impacts on a marine mammal stock or
species and practicability of
implementation are not issues that can
be meaningfully evaluated through a
yes/no lens. The manner in which, and
the degree to which, implementation of
a measure is expected to reduce
impacts, as well as its practicability, can
vary widely. For example, a time-area
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restriction could be of very high value
for decreasing population-level impacts
(e.g., avoiding disturbance of feeding
females in an area of established
biological importance) or it could be of
lower value (e.g., decreased disturbance
in an area of high productivity but of
less firmly established biological
importance). Regarding practicability, a
measure might involve operational
restrictions that completely impede the
operator’s ability to acquire necessary
data (higher impact), or it could mean
additional incremental delays that
increase operational costs but still allow
the activity to be conducted (lower
impact). A responsible evaluation of
‘‘least practicable adverse impact’’ will
consider the factors along these realistic
scales. Expected effects of the activity
and of the mitigation as well as status
of the stock all weigh into these
considerations. Accordingly, the greater
the likelihood that a measure will
contribute to reducing the probability or
severity of adverse impacts to the
species or stock or their habitat, the
greater the weight that measure is given
when considered in combination with
practicability to determine the
appropriateness of the mitigation
measure, and vice versa. We discuss
consideration of these factors in greater
detail below.
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1. Reduction of Adverse Impacts to
Marine Mammal Species or Stocks and
Their Habitat 4
The emphasis given to a measure’s
ability to reduce the impacts on a
species or stock considers the degree,
likelihood, and context of the
anticipated reduction of impacts to
individuals as well as the status of the
species or stock.
The ultimate impact on any
individual from a disturbance event
(which informs the likelihood of
adverse species- or stock-level effects) is
dependent on the circumstances and
associated contextual factors, such as
duration of exposure to stressors.
Though any required mitigation needs
to be evaluated in the context of the
specific activity and the species or
stocks affected, measures with the
following types of goals are expected to
reduce the likelihood or severity of
4 We recognize the least practicable adverse
impact standard requires consideration of measures
that will address minimizing impacts on the
availability of the species or stocks for subsistence
uses where relevant. Because subsistence uses are
not implicated for this action we do not discuss
them. However, a similar framework would apply
for evaluating those measures, taking into account
the MMPA’s directive that we make a finding of no
unmitigable adverse impact on the availability of
the species or stocks for taking for subsistence, and
the relevant implementing regulations.
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adverse species- or stock-level impacts:
Avoiding or minimizing injury or
mortality; limiting interruption of
known feeding, breeding, mother/calf,
or resting behaviors; minimizing the
abandonment of important habitat
(temporally and spatially); minimizing
the number of individuals subjected to
these types of disruptions; and limiting
degradation of habitat. Mitigating these
types of effects is intended to reduce the
likelihood that the activity will result in
energetic or other types of impacts that
are more likely to result in reduced
reproductive success or survivorship. It
is also important to consider the degree
of impacts that are expected in the
absence of mitigation in order to assess
the added value of any potential
measures. Finally, because the least
practicable adverse impact standard
gives NMFS the discretion to weigh a
variety of factors when determining
what should be included as appropriate
mitigation measures and because the
focus is on reducing impacts at the
species or stock level, it does not
compel mitigation for every kind of
individual take, even when practicable
for implementation by the applicant.
The status of the species or stock is
also relevant in evaluating the
appropriateness of potential mitigation
measures in the context of least
practicable adverse impact. The
following are examples of factors that
may (either alone, or in combination)
result in greater emphasis on the
importance of a mitigation measure in
reducing impacts on a species or stock:
The stock is known to be decreasing or
status is unknown, but believed to be
declining; the known annual mortality
(from any source) is approaching or
exceeding the PBR level; the affected
species or stock is a small, resident
population; or the stock is involved in
a UME or has other known
vulnerabilities.
Habitat mitigation, particularly as it
relates to rookeries, mating grounds, and
areas of similar significance, is also
relevant to achieving the standard and
can include measures such as reducing
impacts of the activity on known prey
utilized in the activity area or reducing
impacts on physical habitat. As with
species- or stock-related mitigation, the
emphasis given to a measure’s ability to
reduce impacts on a species or stock’s
habitat considers the degree, likelihood,
and context of the anticipated reduction
of impacts to habitat. Because habitat
value is informed by marine mammal
presence and use, in some cases there
may be overlap in measures for the
species or stock and for use of habitat.
We consider available information
indicating the likelihood of any measure
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to accomplish its objective. If evidence
shows that a measure has not typically
been effective or successful, then either
that measure should be modified or the
potential value of the measure to reduce
effects is lowered.
2. Practicability
Factors considered may include those
such as cost, impact on operations,
personnel safety, and practicality of
implementation.
In carrying out the MMPA’s mandate
for these five IHAs, we apply the
previously described context-specific
balance between the manner in which
and the degree to which measures are
expected to reduce impacts to the
affected species or stocks and their
habitat and practicability for the
applicant. The effects of concern (i.e.,
those with the potential to adversely
impact species or stocks and their
habitat), addressed previously in the
‘‘Potential Effects of the Specified
Activity on Marine Mammals and Their
Habitat’’ section, include auditory
injury, severe behavioral reactions,
disruptions of critical behaviors, and to
a lesser degree, masking and impacts on
acoustic habitat (see discussion of this
concept in the ‘‘Anticipated Effects on
Marine Mammal Habitat’’ section in the
Notice of Proposed IHAs). Here, we
focus on measures with proven or
reasonably presumed ability to avoid or
reduce the intensity of acute exposures
that have potential to result in these
anticipated effects with an
understanding of the drawbacks or costs
of these requirements, as well as timearea restrictions that would avoid or
reduce both acute and chronic impacts.
To the extent of the information
available to us, we considered
practicability concerns, as well as
potential undesired consequences of the
measures, e.g., extended periods using
the acoustic source due to the need to
reshoot lines. We also recognize that
instantaneous protocols, such as
shutdown requirements, are not capable
of avoiding all acute effects, and are not
suitable for avoiding many cumulative
or chronic effects and do not provide
targeted protection in areas of greatest
importance for marine mammals.
Therefore, in addition to a basic suite of
seismic mitigation protocols, we also
consider measures that may or may not
be appropriate for other activities (e.g.,
time-area restrictions specific to the
surveys discussed herein) but that are
warranted here given the spatial scope
of these specified activities, potential for
population-level effects and/or high
magnitude of take for certain species in
the absence of such mitigation (see
‘‘Negligible Impact Analyses and
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Determinations’’), and the information
we have regarding habitat for certain
species.
In order to satisfy the MMPA’s least
practicable adverse impact standard, we
evaluated a suite of basic mitigation
protocols that are required regardless of
the status of a stock. Additional or
enhanced protections are required for
species whose stocks are in poor health
and/or are subject to some significant
additional stressor that lessens that
stock’s ability to weather the effects of
the specified activities without
worsening its status. We reviewed the
applicants’ proposals, the requirements
specified in BOEM’s PEIS, seismic
mitigation protocols required or
recommended elsewhere (e.g., HESS,
1999; DOC, 2013; IBAMA, 2005; Kyhn
et al., 2011; JNCC, 2017; DEWHA, 2008;
BOEM, 2016a; DFO, 2008; GHFS, 2015;
MMOA, 2015; Nowacek et al., 2013;
Nowacek and Southall, 2016), and the
available scientific literature. We also
considered recommendations given in a
number of review articles (e.g., Weir and
Dolman, 2007; Compton et al., 2008;
Parsons et al., 2009; Wright and
Cosentino, 2015; Stone, 2015b). Certain
changes from the mitigation measures
described in our Notice of Proposed
IHAs were made on the basis of
additional information and following
review of public comments. The
required suite of mitigation measures
differs in some cases from the measures
proposed by the applicants and/or those
specified by BOEM in their PEIS and
Record of Decision (ROD) in order to
reflect what we believe to be the most
appropriate suite of measures to satisfy
the requirements of the MMPA.
First, we summarize notable changes
made to the mitigation requirements as
a result of review of public comments
and then describe mitigation prescribed
in the issued IHAs. For additional detail
regarding mitigation considerations,
including expected efficacy and/or
practicability, or descriptions of
mitigation considered but not required,
please see our Notice of Proposed IHAs.
Here we provide a single description
of required mitigation measures, as we
require the same measures of all
applicants.
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Changes From the Notice of Proposed
IHAs
Here we summarize substantive
changes to mitigation requirements from
our Notice of Proposed IHAs. All
changes were made on the basis of
review of public comments received,
including from applicants, and/or
review of new information.
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Time-Area Restrictions
• We spatially expanded the
proposed time-area restriction for North
Atlantic right whales. Our proposed
restriction area was comprised of an
area containing three distinct areas: (1)
A 20-nmi coastal strip throughout the
specific geographic region; (2)
designated Seasonal Management Areas;
and (3) designated critical habitat. This
combined area was then buffered by 10
km, resulting in an approximate 47-km
standoff distance. We received
numerous public comments expressing
concern regarding the adequacy of this
measure and, more generally, regarding
the status of the North Atlantic right
whale. Also, since publication of the
Notice of Proposed IHAs, the status of
this population has worsened, including
declaration of an ongoing UME. Given
this, we considered newly available
information (e.g., Roberts et al., 2017;
Davis et al., 2017) and re-evaluated the
restriction. This is described in more
detail under ‘‘Comments and
Responses’’ as well as later in this
section. Following this review, we
expanded the restriction to 80 km from
shore, with the same 10-km buffer, for
a total 90-km restriction. As was
proposed, the restriction would be in
effect from November through April.
However, in lieu of this requirement,
applicants may alternatively develop
and submit a monitoring and mitigation
plan for NMFS’s approval that would be
sufficient to achieve comparable
protection for North Atlantic right
whales. If approved, applicants would
be required to maintain a minimum
coastal standoff distance of 47 km from
November through April while
operating in adherence with the
approved plan from 47 through 80 km
offshore. (Note that the 80 km distance
is assumed to represent to a reasonable
extent right whale occurrence on the
migratory pathway; therefore, under an
approved plan the 10-km buffer would
not be relevant.)
• We shifted the timing of the
‘‘Hatteras and North’’ time-area
restriction (Area #4 in Figure 4 and
Table 7; described as Area #5 in our
Notice of Proposed IHAs), developed
primarily to benefit beaked whales,
sperm whales, and pilot whales, but
also to provide seasonal protection to a
notable biodiversity hotspot. The timing
of this restriction, proposed as July
through September (Roberts et al.,
2015n), is shifted to January through
March on the basis of new information
(Stanistreet et al., 2018), as described in
more detail later in this section. The
restriction area remains the same.
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• We eliminated the proposed
(former) Area #1, which was delineated
in an effort to reduce likely acoustic
exposures for the species for three
applicants only, as opposed to a more
meaningful reduction of impacts in
important habitat and/or for species
expected to be more sensitive to
disturbance from airgun noise. As was
stated in our Notice of Proposed IHAs,
‘‘Although there are no relevant
considerations with regard to
population context or specific stressors
that lead us to develop mitigation
focused on Atlantic spotted dolphins
[ . . . ] we believe it appropriate to
delineate a time-area restriction for the
sole purpose of reducing likely acoustic
exposures for the species [for three
companies].’’ We received comments on
this proposed restriction from several
commenters who provided compelling
rationale to eliminate the measure. As
was stated in our Notice of Proposed
IHAs, Atlantic spotted dolphins display
a bifurcated distribution, with a portion
of the stock inhabiting the continental
shelf south of Cape Hatteras inside the
200-m isobath and a portion of the stock
off the shelf and north of the Gulf
Stream (north of Cape Hatteras). Our
proposed restriction—located in the
southern, on-shelf portion of the range,
which we believe to be more predictable
habitat for the species—was not likely to
have the intended effect, as a seasonal
restriction would not necessarily reduce
acoustic exposures for a species that is
not known to migrate in and out of the
restriction area, and because a relatively
small portion of overall survey effort
was planned for this area.
Implementation of this restriction
would also likely have meaningful
practicability implications for
applicants with survey lines in the area,
as they would need to plan for both the
seasonal restriction for spotted dolphin
(proposed as July through September) as
well as the right whale restriction,
which overlaps the proposed spotted
dolphin area and would be in effect
from November through April.
Therefore, the proposal would not likely
provide commensurate benefit to the
species to offset these concerns.
Shutdown Requirements
• In our Notice of Proposed IHAs, we
proposed an exception to the general
shutdown requirements for certain
species of dolphins in certain
circumstances. Specifically, we
proposed that the exception to the
shutdown requirement would apply if
the animals are traveling, including
approaching the vessel. Our rationale in
proposing this specific exception was to
avoid the perceived subjective decision-
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making associated with an exception
based on a determination that dolphins
were approaching voluntarily, while
still protecting dolphins from
disturbance of potentially important
behaviors such as feeding or
socialization, as might be indicated by
the presence of dolphins engaged in
behavior other than traveling (e.g.,
milling). Although the ‘‘bow-riding’’
dolphin exception was similarly
criticized when presented for public
comment in BOEM’s draft PEIS, we
agree that our proposal (i.e., based on
‘‘traveling’’ versus ‘‘stationary’’
dolphins in relation to the vessel’s
movement) was unclear and that it
would not likely result in an
improvement with regard to clarity of
protected species observer (PSO)
decision-making. Therefore, this
proposal was properly considered
impracticable, while not offering
meaningfully commensurate biological
benefit. While we are careful to note
that we do not fully understand the
reasons for and potential effects of
dolphin interaction with vessels,
including working survey vessels, we
also understand that dolphins are
unlikely to incur any degree of
threshold shift due to their relative lack
of sensitivity to the frequency content in
an airgun signal (as well as because of
potential coping mechanisms). We also
recognize that, although dolphins do in
fact react to airgun noise in ways that
may be considered take (Barkaszi et al.,
2012), there is a lack of notable adverse
dolphin reactions to airgun noise
despite a large body of observational
data. Therefore, the removal of the
conditional shutdown measure for small
delphinids is warranted in
consideration of the available
information regarding the effectiveness
of such measures in mitigating impacts
to small delphinids and the
practicability of such measures. No
shutdown is required for these species.
• We proposed a number of expanded
shutdown requirements on the basis of
detections of certain species deemed
particularly sensitive (e.g., beaked
whales) or of particular circumstances
deemed to warrant the expanded
shutdown requirement (e.g., whales
with calves). These were all conditioned
upon observation or detection of these
species or circumstances at any distance
from the vessel. We received several
comments challenging the value of
expanded shutdown requirements at all
and, while we disagree with these
comments, we agree that some
reasonable distance limit should be
placed on these requirements in order to
better focus the observational effort of
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PSOs and to avoid the potential for
numerous shutdowns based on
uncertain detections at great distance.
Therefore, as described in greater detail
later in this section, we limit such
expanded shutdown zones for relevant
species or circumstances to 1.5 km.
• We eliminated a proposed
requirement for shutdowns upon
observation of a diving sperm whale at
any distance centered on the forward
track of the source vessel. We received
several comments indicating that this
proposed requirement was unclear in
terms of how it was to be implemented,
and that the benefit to the species was
poorly demonstrated. We agree with
these comments.
• We eliminated a proposed
requirement for shutdowns upon
detection of fin whales at any distance
(proposed for TGS only). As stated in
our Notice of Proposed IHAs, this
requirement was proposed only on the
basis of a high predicted amount of
exposures. Following review of this
requirement, we recognize that it would
not be effective in achieving the stated
goal of reducing the overall amount of
takes, as any observed fin whale would
still be within the Level B harassment
zone and thus taken. Therefore, this
measure serves no meaningful purpose
while imposing an additional
practicability burden on TGS.
• We clarify that the proposed
requirement to shut down upon
observation of an aggregation of marine
mammals applies only to large whales
(i.e., baleen whales and sperm whales),
as was our intent. Several commenters
interpreted the requirement as applying
to all marine mammals and noted that
this would require a significant increase
in shutdowns as a result of the
prevalence of observations of dolphins
in groups exceeding five (most dolphin
species have average group sizes larger
than five). It has been common practice
in prior issued IHAs for similar
activities to require such a measure for
whale species; however, we
inadvertently omitted this key detail in
describing the proposed measure. Also,
we remove the language regarding
‘‘traveling,’’ which had been proposed
in a similar context as was discussed
above for small delphinids and which
we have determined to be a poorly
defined condition.
Monitoring
• We require that at least two acoustic
PSOs have prior experience (minimum
90 days) working in that role, on the
basis of discussion with experts who
emphasized the critical importance of
experience for acoustic PSOs (e.g.,
Thode et al., 2017; pers. comm., D.
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Epperson, BSEE). Our proposal required
that only one acoustic PSO have prior
experience.
Below, we describe mitigation
requirements in detail.
Mitigation-Related Monitoring
Monitoring by independent,
dedicated, trained marine mammal
observers is required. Note that,
although we discuss requirements
related only to observation of marine
mammals, we hereafter use the generic
term ‘‘protected species observer’’
(PSO). Independent observers are
employed by a third-party observer
provider; vessel crew may not serve as
PSOs. Dedicated observers are those
who have no tasks other than to conduct
observational effort, record
observational data, and communicate
with and instruct the survey operator
(i.e., vessel captain and crew) with
regard to the presence of marine
mammals and mitigation requirements.
Communication with the operator may
include brief alerts regarding maritime
hazards. Trained PSOs have
successfully completed an approved
PSO training course (see ‘‘Monitoring
and Reporting’’), and experienced PSOs
have additionally gained a minimum of
90 days at-sea experience working as a
PSO during a deep penetration seismic
survey, with no more than 18 months
having elapsed since the conclusion of
the relevant at-sea experience. Training
and experience is specific to either
visual or acoustic PSO duties. An
experienced visual PSO must have
completed approved, relevant training
and must have gained the requisite
experience working as a visual PSO. An
experienced acoustic PSO must have
completed a passive acoustic
monitoring (PAM) operator training
course and must have gained the
requisite experience working as an
acoustic PSO. Hereafter, we also refer to
acoustic PSOs as PAM operators.
NMFS expects to provide informal
approval for specific training courses as
needed to approve PSO staffing plans.
NMFS does not plan to formally
administer any training program or to
sanction any specific provider, but will
approve courses that meet the
curriculum and trainer requirements
specified herein (see ‘‘Monitoring and
Reporting’’). We expect to provide such
approvals in context of the need to
ensure that PSOs have the necessary
training to carry out their duties
competently while also approving
applicant staffing plans quickly. In
order for PSOs to be approved, NMFS
must review and approve PSO resumes
accompanied by a relevant training
course information packet that includes
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the name and qualifications (i.e.,
experience, training completed, or
educational background) of the
instructor(s), the course outline or
syllabus, and course reference material
as well as a document stating the PSO’s
successful completion of the course.
Although NMFS must affirm PSO
approvals, third-party observer
providers and/or companies seeking
PSO staffing should expect that
observers having satisfactorily
completed approved training and with
the requisite experience (if required)
will be quickly approved. A PSO may be
trained and/or experienced as both a
visual PSO and PAM operator and may
perform either duty, pursuant to
scheduling requirements. PSO watch
schedules shall be devised in
consideration of the following
restrictions: (1) A maximum of two
consecutive hours on watch followed by
a break of at least one hour between
watches for visual PSOs (periods typical
of observation for research purposes and
as used for airgun surveys in certain
circumstances (Broker et al., 2015)); (2)
a maximum of four consecutive hours
on watch followed by a break of at least
two consecutive hours between watches
for PAM operators; and (3) a maximum
of 12 hours observation per 24-hour
period. Further information regarding
PSO requirements may be found in the
‘‘Monitoring and Reporting’’ section,
later in this document.
During survey operations (e.g., any
day on which use of the acoustic source
is planned to occur; whenever the
acoustic source is in the water, whether
activated or not), a minimum of two
PSOs must be on duty and conducting
visual observations at all times during
daylight hours (i.e., from 30 minutes
prior to sunrise through 30 minutes
following sunset) and 30 minutes prior
to and during nighttime ramp-ups of the
airgun array (see ‘‘Ramp-ups’’ below).
PSOs should use NOAA’s solar
calculator (www.esrl.noaa.gov/gmd/
grad/solcalc/) to determine sunrise and
sunset times at their specific location.
We recognize that certain daytime
conditions (e.g., fog, heavy rain) may
reduce or eliminate effectiveness of
visual observations; however, on-duty
PSOs shall remain alert for marine
mammal observational cues and/or a
change in conditions.
All source vessels must carry a
minimum of one experienced visual
PSO, who shall be designated as the
lead PSO, coordinate duty schedules
and roles, and serve as primary point of
contact for the operator. However, while
it is desirable for all PSOs to be
qualified through experience, we are
also mindful of the need to expand the
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workforce by allowing opportunity for
newly trained PSOs to gain experience.
Therefore, the lead PSO shall devise the
duty schedule such that experienced
PSOs are on duty with trained PSOs
(i.e., those PSOs with appropriate
training but who have not yet gained
relevant experience) to the maximum
extent practicable in order to provide
necessary mentorship.
With regard to specific observational
protocols, we largely follow those
described in Appendix C of BOEM’s
PEIS (BOEM, 2014a). The lead PSO
shall determine the most appropriate
observation posts that will not interfere
with navigation or operation of the
vessel while affording an optimal,
elevated view of the sea surface; these
should be the highest elevation
available on each vessel, with the
maximum viewable range from the bow
to 90 degrees to port or starboard of the
vessel. PSOs shall coordinate to ensure
360° visual coverage around the vessel,
and shall conduct visual observations
using binoculars and the naked eye
while free from distractions and in a
consistent, systematic, and diligent
manner. All source vessels must be
equipped with pedestal-mounted
‘‘bigeye’’ binoculars that will be
available for PSO use. Within these
broad outlines, the lead PSO and PSO
team will have discretion to determine
the most appropriate vessel- and surveyspecific system for implementing
effective marine mammal observational
effort. Any observations of marine
mammals by crew members aboard any
vessel associated with the survey,
including chase vessels, should be
relayed to the source vessel and to the
PSO team.
All source vessels must use a towed
PAM system for potential detection of
marine mammals. The system must be
monitored at all times during use of the
acoustic source, and acoustic
monitoring must begin at least 30
minutes prior to ramp-up. PAM
operators must be independent, and all
source vessels shall carry a minimum of
two experienced PAM operators. PAM
operators shall communicate all
detections to visual PSOs, when visual
PSOs are on duty, including any
determination by the PSO regarding
species identification, distance and
bearing and the degree of confidence in
the determination. Further detail
regarding PAM system requirements
may be found in the ‘‘Monitoring and
Reporting’’ section, later in this
document. The effectiveness of PAM
depends to a certain extent on the
equipment and methods used and
competency of the PAM operator, but no
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established standards are currently in
place.
Visual monitoring must begin at least
30 minutes prior to ramp-up (described
below) and must continue until one
hour after use of the acoustic source
ceases or until 30 minutes past sunset.
If any marine mammal is observed at
any distance from the vessel, a PSO
would record the observation and
monitor the animal’s position (including
latitude/longitude of the vessel and
relative bearing and estimated distance
to the animal) until the animal dives or
moves out of visual range of the
observer. A PSO would continue to
observe the area to watch for the animal
to resurface or for additional animals
that may surface in the area. Visual
PSOs shall communicate all
observations to PAM operators,
including any determination by the PSO
regarding species identification,
distance, and bearing and the degree of
confidence in the determination.
As noted previously, all source
vessels must carry a minimum of one
experienced visual PSO and two
experienced PAM operators. The
observer designated as lead PSO
(including the full team of visual PSOs
and PAM operators) must have
experience as a visual PSO. The
applicant may determine how many
additional PSOs are required to
adequately fulfill the requirements
specified here. To summarize, these
requirements are: (1) 24-hour acoustic
monitoring during use of the acoustic
source; (2) visual monitoring during use
of the acoustic source by two PSOs
during all daylight hours, with one
visual PSO on-duty during nighttime
ramp-ups; (3) maximum of two
consecutive hours on watch followed by
a minimum of one hour off watch for
visual PSOs and a maximum of four
consecutive hours on watch followed by
a minimum of two consecutive hours off
watch for PAM operators; and (4)
maximum of 12 hours of observational
effort per 24-hour period for any PSO,
regardless of duties.
PAM Malfunction—Emulating
sensible protocols described by the New
Zealand Department of Conservation for
airgun surveys conducted in New
Zealand waters (DOC, 2013), survey
activity may continue for brief periods
of time when the PAM system
malfunctions or is damaged. Activity
may continue for 30 minutes without
PAM while the PAM operator diagnoses
the issue. If the diagnosis indicates that
the PAM system must be repaired to
solve the problem, operations may
continue for an additional two hours
without acoustic monitoring under the
following conditions:
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• Daylight hours and sea state is less
than or equal to Beaufort sea state (BSS)
4;
• No marine mammals (excluding
delphinids; see below) detected solely
by PAM in the exclusion zone (see
below) in the previous two hours;
• NMFS is notified via email as soon
as practicable with the time and
location in which operations began
without an active PAM system; and
• Operations with an active acoustic
source, but without an operating PAM
system, do not exceed a cumulative total
of four hours in any 24-hour period.
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Exclusion Zone and Buffer Zone
An exclusion zone is a defined area
within which occurrence of a marine
mammal triggers mitigation action
intended to reduce potential for certain
outcomes, e.g., auditory injury, more
severe disruption of behavioral patterns.
The PSOs shall establish and monitor a
500-m exclusion zone and additional
500-m buffer zone (total 1,000 m) during
the pre-clearance period (see below) and
a 500-m exclusion zone during the
ramp-up and operational periods. PSOs
should focus their observational effort
within this 1-km zone, although animals
observed at greater distances should be
recorded and mitigation action taken as
necessary (see below). These zones shall
be based upon radial distance from any
element of the airgun array (rather than
being based on the center of the array
or around the vessel itself). During use
of the acoustic source, occurrence of
marine mammals within the buffer zone
(but outside the exclusion zone) should
be communicated to the operator to
prepare for the potential shutdown of
the acoustic source. Use of the buffer
zone in relation to ramp-up is discussed
below under ‘‘Ramp-up.’’ Further detail
regarding the exclusion zone and
shutdown requirements is given under
‘‘Exclusion Zone and Shutdown
Requirements.’’
Ramp-Up
Ramp-up of an acoustic source is
intended to provide a gradual increase
in sound levels, enabling animals to
move away from the source if the signal
is sufficiently aversive prior to its
reaching full intensity. We infer on the
basis of behavioral avoidance studies
and observations that this measure
results in some reduced potential for
auditory injury and/or more severe
behavioral reactions. Although this
measure is not proven and some
arguments have been made that use of
ramp-up may not have the desired effect
of aversion (which is itself a potentially
negative impact but assumed to be
better than the alternative), ramp-up
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remains a relatively low-cost, commonsense component of standard mitigation
for airgun surveys. Ramp-up is most
likely to be effective for more sensitive
species (e.g., beaked whales) with
known behavioral responses at greater
distances from an acoustic source (e.g.,
Tyack et al., 2011; DeRuiter et al., 2013;
Miller et al., 2015).
The ramp-up procedure involves a
step-wise increase in the number of
airguns firing and total array volume
until all operational airguns are
activated and the full volume is
achieved. Ramp-up is required at all
times as part of the activation of the
acoustic source (including source tests;
see ‘‘Miscellaneous Protocols’’ for more
detail) and may occur at times of poor
visibility, assuming appropriate acoustic
monitoring with no detections in the 30
minutes prior to beginning ramp-up.
Acoustic source activation should only
occur at night where operational
planning cannot reasonably avoid such
circumstances. For example, a nighttime
initial ramp-up following port departure
is reasonably avoidable and may not
occur. Ramp-up may occur at night
following acoustic source deactivation
due to line turn or mechanical
difficulty. The operator must notify a
designated PSO of the planned start of
ramp-up as agreed-upon with the lead
PSO; the notification time should be at
least 60 minutes prior to the planned
ramp-up. A designated PSO must be
notified again immediately prior to
initiating ramp-up procedures and the
operator must receive confirmation from
the PSO to proceed.
Ramp-up procedures follow the
recommendations of IAGC (2015).
Ramp-up would begin by activating a
single airgun (i.e., array element) of the
smallest volume in the array. Ramp-up
continues in stages by doubling the
number of active elements at the
commencement of each stage, with each
stage of approximately the same
duration. Total duration should not be
less than approximately 20 minutes but
maximum duration is not prescribed
and will vary depending on the total
number of stages. Von Benda-Beckmann
et al. (2013), in a study of the
effectiveness of ramp-up for sonar,
found that extending the duration of
ramp-up did not have a corresponding
effect on mitigation benefit. There will
generally be one stage in which
doubling the number of elements is not
possible because the total number is not
even. This should be the last stage of the
ramp-up sequence. The operator must
provide information to the PSO
documenting that appropriate
procedures were followed. Ramp-ups
should be scheduled so as to minimize
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the time spent with the source activated
prior to reaching the designated run-in.
This approach is intended to ensure a
perceptible increase in sound output per
increment while employing increments
that produce similar degrees of increase
at each step.
PSOs must monitor a 1,000-m zone
(or to the distance visible if less than
1,000 m) for a minimum of 30 minutes
prior to ramp-up (i.e., pre-clearance).
The pre-clearance period may occur
during any vessel activity (i.e., transit,
line turn). Ramp-up must be planned to
occur during periods of good visibility
when possible; operators may not target
the period just after visual PSOs have
gone off duty. Following deactivation of
the source for reasons other than
mitigation, the operator must
communicate the near-term operational
plan to the lead PSO with justification
for any planned nighttime ramp-up.
Any suspected patterns of abuse must
be reported by the lead PSO to be
investigated by NMFS. Ramp-up may
not be initiated if any marine mammal
is within the designated 1,000-m zone.
If a marine mammal is observed within
the zone during the pre-clearance
period, ramp-up may not begin until the
animal(s) has been observed exiting the
zone or until an additional time period
has elapsed with no further sightings
(i.e., 15 minutes for small odontocetes
and 30 minutes for all other species).
PSOs will monitor the 500-m exclusion
zone during ramp-up, and ramp-up
must cease and the source shut down
upon observation of marine mammals
within or approaching the zone.
Exclusion Zone and Shutdown
Requirements
The PSOs must establish a minimum
exclusion zone with a 500-m radius as
a perimeter around the outer extent of
the airgun array (rather than being
delineated around the center of the
array or the vessel itself). If a marine
mammal (other than the small delphinid
species discussed below) appears within
or enters this zone, the acoustic source
must be shut down (i.e., power to the
acoustic source must be immediately
turned off). If a marine mammal is
detected acoustically, the acoustic
source must be shut down, unless the
PAM operator is confident that the
animal detected is outside the exclusion
zone or that the detected species is not
subject to the shutdown requirement
(see below).
The 500-m radial distance of the
standard exclusion zone is expected to
contain sound levels exceeding peak
pressure injury criteria for all hearing
groups other than, potentially, highfrequency cetaceans, while also
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providing a consistent, reasonably
observable zone within which PSOs
would typically be able to conduct
effective observational effort. Although
significantly greater distances may be
observed from an elevated platform
under good conditions, we believe that
500 m is likely regularly attainable for
PSOs using the naked eye during typical
conditions. In addition, an exclusion
zone is expected to be helpful in
avoiding more severe behavioral
responses. Behavioral response to an
acoustic stimulus is determined not
only by received level but by context
(e.g., activity state) including,
importantly, proximity to the source
(e.g., Southall et al., 2007; Ellison et al.,
2012; DeRuiter et al., 2013). In
prescribing an exclusion zone, we seek
not only to avoid most potential
auditory injury but also to reduce the
likely severity of the behavioral
response at a given received level of
sound.
As discussed in our Notice of
Proposed IHAs, use of monitoring and
shutdown measures within defined
exclusion zone distances is inherently
an essentially instantaneous
proposition—a rule or set of rules that
requires mitigation action upon
detection of an animal. This indicates
that defining an exclusion zone on the
basis of cSEL thresholds, which require
that an animal accumulate some level of
sound energy exposure over some
period of time (e.g., 24 hours), has
questionable relevance as a standard
protocol for mobile sources, given the
relative motion of the source and the
animals. A PSO aboard a mobile source
will typically have no ability to monitor
an animal’s position relative to the
acoustic source over relevant time
periods for purposes of understanding
whether auditory injury is likely to
occur on the basis of cumulative sound
exposure and, therefore, whether action
should be taken to avoid such potential.
Cumulative SEL thresholds are more
relevant for purposes of modeling the
potential for auditory injury than they
are for dictating real-time mitigation,
though they can be informative
(especially in a relative sense). We
recognize the importance of the
accumulation of sound energy to an
understanding of the potential for
auditory injury and that it is likely that,
at least for low-frequency cetaceans,
some potential auditory injury is likely
impossible to fully avoid and should be
considered for authorization.
Considering both the dual-metric
thresholds described previously (and
shown in Table 3) and hearing groupspecific marine mammal auditory
weighting functions in the context of the
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airgun sources considered here,
auditory injury zones indicated by the
peak pressure metric are expected to be
predominant for both mid- and highfrequency cetaceans, while zones
indicated by cSEL criteria are expected
to be predominant for low-frequency
cetaceans. Assuming source levels
provided by the applicants and
indicated in Table 1 and spherical
spreading propagation, distances for
exceedance of group-specific peak
injury thresholds were calculated and
are shown in Table 5.
Consideration of auditory injury
zones based on cSEL criteria are
dependent on the animal’s generalized
hearing range and how that overlaps
with the frequencies produced by the
sound source of interest in relation to
marine mammal auditory weighting
functions (NMFS, 2018). As noted
above, these are expected to be
predominant for low-frequency
cetaceans because their most susceptible
hearing range overlaps the low
frequencies produced by airguns, while
the modeling indicates that zones based
on peak pressure criteria dominate for
mid- and high-frequency cetaceans. As
described in detail in our Notice of
Proposed IHAs, we obtained
unweighted spectrum data (modeled in
1 Hz bands) for a reasonably equivalent
acoustic source (i.e., a 36-airgun array
with total volume of 6,600 in3) in order
to evaluate notional zone sizes and to
incorporate NMFS’s technical guidance
weighting functions over an airgun
array’s full acoustic band. Using
NMFS’s associated User Spreadsheet
with hearing group-specific weighted
source levels, and inputs assuming
spherical spreading propagation, a
source velocity of 4.5 kn, shot intervals
specified by the applicants, and pulse
duration of 100 ms, we calculated
potential radial distances to auditory
injury zones (shown in Table 5).
Therefore, our 500-m exclusion zone
contains the entirety of any potential
injury zone for mid-frequency cetaceans
(realistically, there is no such zone, as
discussed above in ‘‘Estimated Take’’),
while the zones within which injury
could occur may be larger for highfrequency cetaceans (on the basis of
peak pressure and depending on the
specific array) and for low-frequency
cetaceans (on the basis of cumulative
sound exposure). Only three species of
high-frequency cetacean could occur in
the planned survey areas: The harbor
porpoise and two species of the Family
Kogiidae. Harbor porpoise are expected
to occur rarely and only in the northern
portion of the survey area. However, we
require an extended shutdown measure
for Kogia spp. to address these potential
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injury concerns (described later in this
section).
In summary, our goal in prescribing a
standard exclusion zone distance is to
(1) encompass zones for most species
within which auditory injury could
occur on the basis of instantaneous
exposure; (2) provide protection from
the potential for more severe behavioral
reactions (e.g., panic, antipredator
response) for marine mammals at
relatively close range to the acoustic
source; (3) enable more effective
implementation of required mitigation
by providing consistency and ease of
implementation for PSOs, who need to
monitor and implement the exclusion
zone; and (4) to define a distance within
which detection probabilities are
reasonably high for most species under
typical conditions. Our use of 500 m as
the zone is not based directly on any
quantitative understanding of the range
at which auditory injury would be
entirely precluded or any range
specifically related to disruption of
behavioral patterns. Rather, we believe
it is a reasonable combination of factors.
This zone has been proven as a feasible
measure through past implementation
by operators in the Gulf of Mexico
(GOM; as regulated by BOEM pursuant
to the Outer Continental Shelf Lands
Act (OCSLA) (43 U.S.C. 1331–1356)). In
summary, a practicable criterion such as
this has the advantage of familiarity and
simplicity while still providing in most
cases a zone larger than relevant
auditory injury zones, given realistic
movement of source and receiver.
Increased shutdowns, without a firm
idea of the outcome the measure seeks
to avoid, simply displace survey activity
in time and increase the total duration
of acoustic influence as well as total
sound energy in the water (due to
additional ramp-up and overlap where
data acquisition was interrupted).
Dolphin Exception—The shutdown
requirement described above is in place
for all marine mammals, with the
exception of small delphinids. As
defined here, the small delphinid group
is intended to encompass those
members of the Family Delphinidae
most likely to voluntarily approach the
source vessel for purposes of interacting
with the vessel and/or airgun array (e.g.,
bow-riding). This exception to the
shutdown requirement applies solely to
specific genera of small dolphins—
Steno, Tursiops, Stenella, Delphinus,
Lagenorhynchus, and Lagenodelphis
(see Table 2)—and applies under all
circumstances, regardless of what the
perception of the animal(s) behavior or
intent may be. Variations of this
measure that include exceptions based
on animal behavior—including that
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described in our Notice of Proposed
IHAs, in which an exception was
proposed to be applied only to
‘‘traveling’’ dolphins—have been
proposed by both NMFS and BOEM and
have been criticized, in part due to the
subjective on-the-spot decision-making
this scheme would require of PSOs. If
the mitigation requirements are not
sufficiently clear and objective, the
outcome may be differential
implementation across surveys as
informed by individual PSOs’
experience, background, and/or
training. The exception described here
is based on several factors: The lack of
evidence of or presumed potential for
the types of effects to these species of
small delphinid that our shutdown
requirement for other species seeks to
avoid, the uncertainty and subjectivity
introduced by such a decision
framework, and the practicability
concern presented by the operational
impacts. Despite a large volume of
observational effort during airgun
surveys, including in locations where
dolphin shutdowns have not previously
been required (i.e., the U.S. GOM and
United Kingdom (UK) waters), we are
not aware of accounts of notable adverse
dolphin reactions to airgun noise
(Stone, 2015a; Barkaszi et al., 2012)
other than one isolated incident (Gray
and Van Waerebeek, 2011). Dolphins
have a relatively high threshold for the
onset of auditory injury (i.e., PTS) and
more severe adverse behavioral
responses seem less likely given the
evidence of purposeful approach and/or
maintenance of proximity to vessels
with operating airguns.
The best available scientific evidence
indicates that auditory injury as a result
of airgun sources is extremely unlikely
for mid-frequency cetaceans, primarily
due to a relative lack of sensitivity and
susceptibility to noise-induced hearing
loss at the frequency range output by
airguns (i.e., most sound below 500 Hz)
as shown by the mid-frequency cetacean
auditory weighting function (NMFS,
2018). Criteria for TTS in mid-frequency
cetaceans for impulsive sounds were
derived by experimental measurement
of TTS in beluga whales exposed to
pulses from a seismic watergun;
dolphins exposed to the same stimuli in
this study did not display TTS
(Finneran et al., 2002). Moreover, when
the experimental watergun signal was
weighted appropriately for midfrequency cetaceans, less energy was
filtered than would be the case for an
airgun signal. More recently, Finneran
et al. (2015) exposed bottlenose
dolphins to repeated pulses from an
airgun and measured no TTS.
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We caution that, while dolphins are
observed voluntarily approaching
source vessels (e.g., bow-riding or
interacting with towed gear), the reasons
for the behavior are unknown. In
context of an active airgun array, the
behavior cannot be assumed to be
harmless. Although bow-riding
comprises approximately 30 percent of
behavioral observations in the GOM,
there is a much lower incidence of the
behavior when the acoustic source is
active (Barkaszi et al., 2012), and this
finding was replicated by Stone (2015a)
for surveys occurring in UK waters.
There appears to be evidence of aversive
behavior by dolphins during firing of
airguns. Barkaszi et al. (2012) found that
the median closest distance of approach
to the acoustic source was at
significantly greater distances during
times of full-power source operation
when compared to silence, while Stone
(2015a) and Stone and Tasker (2006)
reported that behavioral responses,
including avoidance and changes in
swimming or surfacing behavior, were
evident for dolphins during firing of
large arrays. Goold and Fish (1998)
described a ‘‘general pattern of localized
disturbance’’ for dolphins in the vicinity
of an airgun survey. However, while
these general findings—typically,
dolphins will display increased distance
from the acoustic source, decreased
prevalence of ‘‘bow-riding’’ activities,
and increases in surface-active
behaviors—are indicative of adverse or
aversive responses that may rise to the
level of ‘‘take’’ (as defined by the
MMPA), they are not indicative of any
response of a severity such that the need
to avoid it outweighs the impact on
practicability for the industry and
operators.
Additionally, increased shutdowns
resulting from such a measure would
require source vessels to revisit the
missed track line to reacquire data,
resulting in an overall increase in the
total sound energy input to the marine
environment and an increase in the total
duration over which the survey is active
in a given area. Therefore, the removal
of such measures for small delphinids is
warranted in consideration of the
available information regarding the
effectiveness of such measures in
mitigating impacts to small delphinids
and the practicability of such measures.
Although other mid-frequency
hearing specialists (e.g., large
delphinids) are considered no more
likely to incur auditory injury than are
small delphinids, they are more
typically deep divers, meaning that
there is some increased potential for
more severe effects from a behavioral
reaction, as discussed in greater detail
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in ‘‘Comments and Responses.’’
Therefore, we anticipate benefit from a
shutdown requirement for large
delphinids in that it is likely to preclude
more severe behavioral reactions for any
such animals in close proximity to the
source vessel as well as any potential for
physiological effects.
At the same time, large delphinids are
much less likely to approach vessels.
Therefore, a shutdown requirement for
large delphinids would not have similar
impacts as a small delphinid shutdown
in terms of either practicability for the
applicant or corollary increase in sound
energy output and time on the water.
Other Shutdown Requirements—
Shutdown of the acoustic source is also
required in the event of certain other
observations beyond the standard 500-m
exclusion zone. In our Notice of
Proposed IHAs, we proposed to
condition these shutdowns upon
detection of the relevant species or
circumstances at any distance.
Following review of public comments,
we determined it appropriate to limit
such shutdown requirements to within
a reasonable detection radius of 1.5 km.
This maintains the intent of the
measures as originally proposed, i.e., to
provide for additional real-time
protection by limiting the intensity and
duration of acoustic exposures for
certain species or in certain
circumstances, while reducing the area
over which PSOs must maintain
observational effort. As for normal
shutdowns within the standard 500-m
exclusion zone, shutdowns at extended
distance should be made on the basis of
confirmed detections (visual or
acoustic) within the zone.
We determined an appropriate
distance on the basis of available
information regarding detection
functions for relevant species, but note
that, while based on quantitative data,
the distance is an approximate limit that
is merely intended to encompass the
region within which we would expect a
relatively high degree of success in
sighting certain species while also
improving PSO efficacy by removing the
potential that a PSO might interpret
these requirements as demanding a
focus on areas further from the vessel.
For each modeled taxon, Roberts et al.
(2016) fitted detection functions that
modeled the detectability of the taxon
according to distance from the trackline
and other covariates (i.e., the probability
of detecting an animal given its distance
from the transect). These functions were
based on nearly 1.1 million linear km of
line-transect survey effort conducted
from 1992–2014, with surveys arranged
in aerial and shipboard hierarchies and
further grouped according to similarity
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of observation protocol and platform.
Where a taxon was sighted infrequently,
a detection function was fit to pooled
sightings of suitable proxy species. For
example, for the North Atlantic right
whale and shipboard binocular surveys
(i.e., the relevant combination of
platform and protocol), a detection
function was fit using pooled sightings
of right whales and other mysticete
species (Roberts et al., 2015p). The
resulting detection function shows a
slightly more than 20 percent
probability of detecting right whales at
2 km, with a mean effective strip halfwidth (ESHW) (which provides a
measure of how far animals are seen
from the transect line; Buckland et al.,
2001) of 1,309 m (Roberts et al., 2015p).
Similarly, Barlow et al. (2011) reported
mean ESHWs for various mysticete
species ranging from approximately 1.5–
2 km. The detection function used in
modeling density for beaked whales
provided a mean ESHW of 1,587 m
(Roberts et al., 2015l). Therefore, we set
the shutdown radius for special
circumstances (described below) at 1.5
km.
Comments disagreeing with our
proposal to require shutdowns upon
certain detections at any distance also
suggested that the measures did not
have commensurate benefit for the
relevant species. However, it must be
noted that any such observations would
still be within range of where behavioral
disturbance of some form and degree
would be likely to occur (Table 4).
While visual PSOs should focus
observational effort within the vicinity
of the acoustic source and vessel, this
does not preclude them from periodic
scanning of the remainder of the visible
area or from noting observations at
greater distances, and there is no reason
to believe that such periodic scans by
professional PSOs would hamper the
ability to maintain observation of areas
closer to the source and vessel.
Circumstances justifying shutdown at
extended distance (i.e., within 1.5 km)
include:
• Upon detection of a right whale.
Recent data concerning the North
Atlantic right whale, one of the most
endangered whale species (Best et al.,
2001), indicate uncertainty regarding
the population’s recovery and a
possibility of decline (see discussion
under ‘‘Description of Marine Mammals
in the Area of the Specified Activities’’).
We believe it appropriate to eliminate
potential effects to individual right
whales to the extent possible;
• Upon visual observation of a large
whale (i.e., sperm whale or any baleen
whale) with calf, with ‘‘calf’’ defined as
an animal less than two-thirds the body
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size of an adult observed to be in close
association with an adult. Groups of
whales are likely to be more susceptible
to disturbance when calves are present
(e.g., Bauer et al., 1993), and
disturbance of cow-calf pairs could
potentially result in separation of
vulnerable calves from adults.
Separation, if it occurred, could be
exacerbated by airgun signals masking
communication between adults and the
separated calf (Videsen et al., 2017).
Absent separation, airgun signals can
disrupt or mask vocalizations essential
to mother-calf interactions. Given the
consequences of potential loss of calves
in the context of ongoing UMEs for
multiple mysticete species, as well as
the functional sensitivity of the
mysticete whales to frequencies
associated with airgun survey activity,
we believe this measure is warranted;
• Upon detection of a beaked whale
or Kogia spp. These species are
behaviorally sensitive deep divers and it
is possible that disturbance could
provoke a severe behavioral response
leading to injury (e.g., Wursig et al.,
1998; Cox et al., 2006). We recognize
that there are generally low detection
probabilities for beaked whales and
Kogia spp., meaning that many animals
of these species may go undetected.
Barlow (1999) estimates such
probabilities at 0.23 to 0.45 for Cuvier’s
and Mesoplodont beaked whales,
respectively. However, Barlow and
Gisiner (2006) predict a roughly 24–48
percent reduction in the probability of
detecting beaked whales during seismic
mitigation monitoring efforts as
compared with typical research survey
efforts, and Moore and Barlow (2013)
noted a decrease in g(0) for Cuvier’s
beaked whales from 0.23 at BSS 0 (calm)
to 0.024 at BSS 5. Similar detection
probabilities have been noted for Kogia
spp., though they typically travel in
smaller groups and are less vocal, thus
making detection more difficult (Barlow
and Forney, 2007). As discussed
previously in this document (see
‘‘Estimated Take’’), there are high levels
of predicted exposures for beaked
whales in particular. Additionally for
high-frequency cetaceans such as Kogia
spp., auditory injury zones relative to
peak pressure thresholds may range
from approximately 350–1,550 m from
the acoustic source, depending on the
specific array characteristics (NMFS,
2018); and
• Upon visual observation of an
aggregation (defined as six or more
animals) of large whales of any species.
Under these circumstances, we assume
that the animals are engaged in some
important behavior (e.g., feeding,
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socializing) that should not be
disturbed.
Shutdown Implementation
Protocols—Any PSO on duty has the
authority to delay the start of survey
operations or to call for shutdown of the
acoustic source. When shutdown is
called for by a PSO, the acoustic source
must be immediately deactivated and
any dispute resolved only following
deactivation. The operator must
establish and maintain clear lines of
communication directly between PSOs
on duty and crew controlling the
acoustic source to ensure that shutdown
commands are conveyed swiftly while
allowing PSOs to maintain watch; handheld UHF radios are recommended.
When both visual PSOs and PAM
operators are on duty, all detections
must be immediately communicated to
the remainder of the on-duty team for
potential verification of visual
observations by the PAM operator or of
acoustic detections by visual PSOs and
initiation of dialogue as necessary.
When there is certainty regarding the
need for mitigation action on the basis
of either visual or acoustic detection
alone, the relevant PSO(s) must call for
such action immediately.
Upon implementation of shutdown,
the source may be reactivated after the
animal(s) has been observed exiting the
exclusion zone or following a 30-minute
clearance period with no further
detection of the animal(s). For harbor
porpoise—the only small odontocete for
which shutdown is required—this
clearance period is limited to 15
minutes.
If the acoustic source is shut down for
reasons other than mitigation (e.g.,
mechanical difficulty) for brief periods
(i.e., less than 30 minutes), it may be
activated again without ramp-up if PSOs
have maintained constant visual and
acoustic observation and no visual
detections of any marine mammal have
occurred within the exclusion zone and
no acoustic detections have occurred.
We define ‘‘brief periods’’ in keeping
with other clearance watch periods and
to avoid unnecessary complexity in
protocols for PSOs. For any longer
shutdown (e.g., during line turns), preclearance watch and ramp-up are
required. For any shutdown at night or
in periods of poor visibility (e.g., BSS 4
or greater), ramp-up is required but if
the shutdown period was brief and
constant observation maintained, preclearance watch is not required.
Power-Down
Power-down, as defined here, refers to
reducing the array to a single element as
a substitute for full shutdown. Use of a
single airgun as a ‘‘mitigation source,’’
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e.g., during extended line turns, is not
allowed. In a power-down scenario, it is
assumed that reducing the size of the
array to a single element reduces the
ensonified area such that an observed
animal is outside of any area within
which injury or more severe behavioral
reactions could occur. Here, powerdown is not allowed for any reason (e.g.,
to avoid pre-clearance and/or ramp-up).
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Miscellaneous Protocols
The acoustic source must be
deactivated when not acquiring data or
preparing to acquire data, except as
necessary for testing. Unnecessary use
of the acoustic source should be
avoided. Firing of the acoustic source at
any volume above the stated production
volume is not authorized for these IHAs;
the operator must provide information
to the lead PSO at regular intervals
confirming the firing volume. Notified
operational capacity (not including
redundant backup airguns) must not be
exceeded during the survey, except
where unavoidable for source testing
and calibration purposes. All occasions
where activated source volume exceeds
notified operational capacity must be
noticed to the PSO(s) on duty and fully
documented for reporting. The lead PSO
must be granted access to relevant
instrumentation documenting acoustic
source power and/or operational
volume.
Testing of the acoustic source
involving all elements requires normal
mitigation protocols (e.g., ramp-up).
Testing limited to individual source
elements or strings does not require
ramp-up but does require pre-clearance.
Restriction Areas
Below we provide discussion of
various time-area restrictions. Because
the purpose of these areas is to reduce
the likelihood of exposing animals
within the designated areas to noise
from airgun surveys that is likely to
result in harassment, we require that
source vessels maintain minimum
standoff distances (i.e., buffers) from the
areas. Sound propagation modeling
results provided for a notional large
airgun array in BOEM’s PEIS indicate
that a 10 km distance would likely
contain received levels of sound
exceeding 160 dB rms under a wide
variety of conditions (e.g., 21 scenarios
encompassing four depth regimes, four
seasons, two bottom types). See
Appendix D of BOEM’s PEIS for more
detail. The 95 percent ranges (i.e., the
radius of a circle encompassing 95
percent of grid points equal to or greater
than the 160 dB threshold value)
provided in Table D–22 of BOEM’s PEIS
range from 4,959–9,122 m, with mean of
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6,838 m. We adopt a standard 10-km
buffer distance to avoid ensonification
above 160 dB rms of restricted areas
under most circumstances.
Coastal Restriction—No survey effort
may occur within 30 km of the coast.
The intent of this restriction is to
provide additional protection for coastal
stocks of bottlenose dolphin, all of
which are designated as depleted under
the MMPA. This designation for all
current coastal stocks is retained from
the originally delineated single coastal
migratory stock, which was revised to
recognize the existence of multiple
stocks in 2002 (Waring et al., 2016). The
prior single coastal stock was designated
as depleted because it was determined
to be below the optimum sustainable
population level (i.e., the number of
animals that will result in the maximum
productivity of the population, keeping
in mind the carrying capacity of their
ecosystem) (Waring et al., 2001).
Already designated as depleted, a UME
affected bottlenose dolphins along the
Atlantic coast, from New York to
Florida, from 2013–15. Genetic analyses
performed to date indicate that 99
percent of dolphins impacted were of
the coastal ecotype, which may be
expected to typically occur within 20
km of the coast. As described above, a
10 km buffer is provided to encompass
the area within which sound exceeding
160 dB rms would reasonably be
expected to occur. Further discussion of
this UME is provided under
‘‘Description of Marine Mammals in the
Area of the Specified Activity.’’
North Atlantic Right Whale—From
November through April, no survey
effort may occur within 90 km of the
coast. In our Notice of Proposed IHAs,
we proposed a similar restriction out to
47 km. The proposed 47-km seasonal
restriction of survey effort was intended
to avoid ensonification by levels of
sound expected to result in behavioral
harassment of particular areas of
expected importance for North Atlantic
right whales, including designated
critical habitat, vessel speed limit
seasonal management areas (SMAs), a
coastal strip containing SMAs, and
vessel speed limit dynamic management
areas (DMAs). This area was expected to
provide substantial protection of right
whales within the migratory corridor
and calving and nursery grounds.
However, following review of comments
received from the Marine Mammal
Commission, as well as other public
comments received and as a result of the
continued deterioration of the status of
this population (described previously in
‘‘Description of Marine Mammals in the
Area of the Specified Activity’’), we
considered new information regarding
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predicted right whale distribution (e.g.,
Roberts et al., 2017; Davis et al., 2017)
and re-evaluated the proposed right
whale time-area restriction.
Specifically, we became aware of an
effort by Roberts et al. to update the
2015 North Atlantic right whale density
models. As described in Roberts et al.
(2017), the updates greatly expanded the
dataset used to derive density outputs,
especially within the planned survey
area, as they incorporated a key dataset
that was not included in the 2015 model
version: Aerial surveys conducted over
multiple years by several organizations
in the southeast United States. In
addition, the AMAPPS survey data were
incorporated into the revised models.
By including these additional data
sources, the number of right whale
sightings used to inform the model
within the planned survey area
increased by approximately 2,500
sightings (approximately 40 sightings
informing the 2015 models versus
approximately 2,560 sightings informing
the updated 2017 models). In addition,
these models incorporated several
improvements to minimize known
biases and used an improved seasonal
definition that more closely aligns with
right whale biology. Importantly, the
revised models showed a strong
relationship between right whale
abundance in the mid-Atlantic during
the winter (December-March) and
distance to shore out to approximately
80 km (Roberts et al., 2017), which was
previously estimated out to
approximately 50 km (Roberts et al.,
2015p). As described above, a 10 km
buffer is provided to encompass the area
within which sound exceeding 160 dB
rms would reasonably be expected to
occur. Mid-Atlantic SMAs for vessel
speed limits are in effect from
November 1 through April 30, while
southeast SMAs are in effect from
November 15 through April 15 (see 50
CFR 224.105). Therefore, the area
discussed here for spatial mitigation
would be in effect from November 1
through April 30.
While we acknowledge that some
whales may be present at distances
further offshore during the November
through April restriction—though
whales are not likely to occur in waters
deeper than 1,500 m—and that there
may be whales present during months
outside the restriction (e.g., Davis et al.,
2017; Krzystan et al., 2018), we have
accounted for the best available
information in reasonably limiting the
potential for acoustic exposure of right
whales to levels exceeding harassment
thresholds. When coupled with the
expanded shutdown provision
described previously for right whales,
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the prescribed mitigation may
reasonably be expected to eliminate
most potential for behavioral
harassment of right whales.
However, as discussed above, in lieu
of this requirement, applicants may
alternatively develop and submit a
monitoring and mitigation plan for
NMFS’s approval that would be
sufficient to achieve comparable
protection for North Atlantic right
whales. If approved, applicants would
be required to maintain a minimum
coastal standoff distance of 47 km from
November through April while
operating in adherence with the
approved plan from 47 through 80 km
offshore. (Note that the 80 km distance
is assumed to represent to a reasonable
extent right whale occurrence on the
migratory pathway; therefore, under an
approved plan the 10-km buffer would
not be relevant.)
DMAs are associated with a scheme
established by the final rule for vessel
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speed limits (73 FR 60173; October 10,
2008; extended by 78 FR 73726;
December 9, 2013) to reduce the risk of
ship strike for right whales. In
association with those regulations,
NMFS established a program whereby
vessels are requested, but not required,
to abide by speed restrictions or avoid
locations when certain aggregations of
right whales are detected outside SMAs.
Generally, the DMA construct is
intended to acknowledge that right
whales can occur outside of areas where
they predictably and consistently occur
due to, e.g., varying oceanographic
conditions that dictate prey
concentrations. NMFS establishes
DMAs by surveying right whale habitat
and, when a specific aggregation is
sighted, creating a temporary zone (i.e.,
DMA) around the aggregation. DMAs are
in effect for 15 days when designated
and automatically expire at the end of
the period, but may be extended if
whales are re-sighted in the same area.
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NMFS issues announcements of
DMAs to mariners via its customary
maritime communication media (e.g.,
NOAA Weather radio, websites, email
and fax distribution lists) and any other
available media outlets. Information on
the possibility of establishment of such
zones is provided to mariners through
written media such as U.S. Coast Pilots
and Notice to Mariners including, in
particular, information on the media
mariners should monitor for notification
of the establishment of a DMA. Upon
notice via the above media of DMA
designation, survey operators must
cease operation within 24 hours if
within 10 km of the boundary of a
designated DMA and may not conduct
survey operations within 10 km of a
designated DMA during the period in
which the DMA is active. It is the
responsibility of the survey operators to
monitor appropriate media and to be
aware of designated DMAs.
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Other Species—Predicted acoustic
exposures are moderate to high for
certain potentially affected marine
mammal species (see Table 6) and,
regardless of the absolute numbers of
predicted exposures, the scope of
planned activities (i.e., survey activity
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throughout substantial portions of many
species range and for substantial
portions of the year) gives rise to
concern regarding the impact on certain
potentially affected stocks. Therefore,
we take the necessary step of identifying
additional spatiotemporal restrictions
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on survey effort, as described here
(Figure 4 and Table 7). In response to
public comment, where possible we
conducted a quantitative assessment of
take avoided (described previously in
‘‘Estimated Take’’). Our qualitative
assessment leads us to believe that
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Figure 3. Time-Area Restriction for North Atlantic Right Whales in Relation to Existing
Areas Designated for Right Whale Protection.
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implementation of these measures is
expected to provide biologically
meaningful benefit for the affected
animals by restricting survey activity
and the effects of the sound produced in
areas of residency and/or preferred
habitat that support higher densities for
the stocks during substantial portions of
the year.
The restrictions described here are
primarily targeted towards protection of
sperm whales, beaked whales (i.e.,
Cuvier’s beaked whale or Mesoplodon
spp. but not the northern bottlenose
whale; see ‘‘Description of Marine
Mammals in the Area of the Specified
Activity’’), and pilot whales. For all
three species or guilds, the amount of
predicted exposures is moderate to high.
The moderate to high amount of
predicted exposures in conjunction with
other contextual elements provides the
impetus to develop appropriate
restrictions. Beaked whales are
considered to be a particularly
acoustically sensitive species. The
sperm whale is an endangered species,
also considered to be acoustically
sensitive and potentially subject to
significant disturbance of important
foraging behavior. Pilot whale
populations in U.S. waters of the
Atlantic are considered vulnerable due
to high levels of mortality in
commercial fisheries, and are therefore
likely to be less resilient to other
stressors, such as disturbance from the
planned surveys.
In some cases, we expect substantial
subsidiary benefit for additional species
that also find preferred habitat in the
designated area of restriction. In
particular, Area #4 (Figure 4), although
delineated in order to specifically
provide an area of anticipated benefit to
beaked whales, sperm whales, and pilot
whales, is expected to host a diverse
cetacean fauna (e.g., McAlarney et al.,
2015). Our analysis (described below)
indicates that species most likely to
derive subsidiary benefit from this timearea restriction include the bottlenose
dolphin, Risso’s dolphin, and common
dolphin. For species with density
predicted through stratified models,
similar analysis is not possible and
assumptions regarding potential benefit
of time-area restrictions are based on
known ecology of the species and
sightings patterns and are less robust.
Nevertheless, subsidiary benefit for
Areas #1–3 (Figure 4) should be
expected for species known to be
present in these areas (e.g., assumed
affinity for slope/abyss areas off Cape
Hatteras): Kogia spp., pantropical
spotted dolphin, Clymene dolphin, and
rough-toothed dolphin.
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We described our rationale for and
development of these time-area
restrictions in detail in our Notice of
Proposed IHAs; please see that
document for more detail. Literature
newly available since publication of the
Notice of Proposed IHAs provides
additional support for the importance of
these areas. For example, McLellan et
al. (2018), reporting the results of aerial
surveys conducted from 2011–2015,
provide additional confirmation that a
portion of the region described below as
Area #4 (‘‘Hatteras and North’’) hosts
high densities of beaked whales,
concluding that the area off Cape
Hatteras at the convergence of the
Labrador Current and Gulf Stream is a
particularly important habitat for
several species of beaked whales.
Stanistreet et al. (2017) report the
results of a multi-year (2011–2015)
passive acoustic monitoring effort to
assess year-round marine mammal
occurrence along the continental slope,
including four locations within the
planned survey area (i.e., Norfolk
Canyon, Cape Hatteras, Onslow Bay,
and Jacksonville) and, in this paper,
they further document the presence of
beaked whales in Area #4. Stanistreet et
al. (2018) report the results of this study
for sperm whale occurrence at the same
sites along the continental slope. These
results showed that sperm whales were
present frequently at the first three sites,
with few detections at Jacksonville. The
greatest monitoring effort was
conducted at the Cape Hatteras site,
where detections were made on 65
percent of 734 recording days across all
seasons. In addition to having the
highest detection rate of sites within the
specific geographic region (in
conjunction with roughly double the
amount of recording effort compared
with the next highest site), Cape
Hatteras exhibited the most distinct
seasonal pattern of any recording site
(Stanistreet et al., 2018). The authors
reported consistently higher sperm
whale occurrence at Cape Hatteras
during the winter than any other season.
On the basis of this new information, we
shifted the timing of the seasonal
restriction in Area #4 from July through
September (as proposed) to January
through March (i.e., ‘‘winter’’;
Stanistreet et al., 2018). Our previously
proposed timing of the seasonal
restriction was based on barely
discernable distribution shifts based on
monthly model predictions (Roberts et
al., 2016). However, the revised timing,
as indicated by Stanistreet et al. (2018),
is generally consistent with the seasonal
shift in sperm whale concentrations
previously described in the western
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North Atlantic (Perry et al., 1999,
Waring et al., 2014).
Please note that, following review of
public comments, former Area #1 was
eliminated from consideration
(discussed in greater detail under
‘‘Comments and Responses’’). Therefore,
numbering of areas described here has
shifted down by one as compared with
the discussion presented in our Notice
of Proposed IHAs, i.e., former Area #5
is now Area #4, etc. In order to consider
potential restriction of survey effort in
time and space, we considered the
outputs of habitat-based predictive
density models (Roberts et al., 2016) as
well as available information
concerning focused marine mammal
studies within the survey areas, e.g.,
photo-identification, telemetry, acoustic
monitoring. The latter information was
used primarily to provide verification
for some of the areas and times
considered, and helps to confirm that
areas of high predicted density are in
fact preferred habitat for these species.
We used the density model outputs by
creating core abundance areas, i.e., an
area that contains some percentage of
predicted abundance for a given species
or species group. We were not able to
consider core abundance areas for
species with stratified models showing
uniform density; however, this
information informs us as to whether
those species may receive subsidiary
benefit from a given time-area
restriction.
A core abundance area is the smallest
area that represents a given percentage
of abundance. As described in our
Notice of Proposed IHAs, we created a
range of core abundance areas for each
species of interest and determined that
in most cases the 25 percent core
abundance area best balanced adequate
protection for the target species with
concerns regarding practicability for
applicants. The larger the percentage of
abundance captured, the larger the area.
However, Area #4 was designed as a
conglomerate by merging areas
indicated to be important through the
core abundance analysis and available
scientific literature for beaked whales,
pilot whales, and sperm whales. In
particular, for sperm whales (which are
predicted to be broadly distributed on
the slope throughout the year), we
included an area predicted to
consistently host higher relative
densities in all months (corresponding
with the five percent core abundance
threshold). We assessed different levels
of core abundance in order to define a
relatively restricted area of preferred
habitat across all seasons. This area in
the vicinity of the shelf break to the
north of Cape Hatteras (which forms the
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conglomerate Area #4), together with
spatially separated canyon features
contained within the 25 percent core
abundance areas and previously
identified as preferred habitat for
beaked whales, form the basis for our
time-area restriction for sperm whales.
Core abundance maps are provided
online at www.fisheries.noaa.gov/
action/incidental-take-authorization-oiland-gas-industry-geophysical-surveyactivity-atlantic.
In summary, we require the following
time-area restrictions:
• In order to protect coastal
bottlenose dolphins, a 30-km coastal
strip (20 km plus 10 km buffer) would
be closed to use of the acoustic source
year-round;
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• In order to protect the North
Atlantic right whale, a 90-km coastal
strip (80 km plus 10 km buffer) would
be closed to use of the acoustic source
from November through April (Figure 3)
(or comparable protection would be
provided through implementation of a
NMFS-approved mitigation and
monitoring plan at distances between
47–80 km offshore). Dynamic
management areas (buffered by 10 km)
are also closed to use of the acoustic
source when in effect;
The 10-km buffer is built into the
areas defined below and in Table 7.
Therefore, we do not separately mention
the addition of the buffer.
• Deepwater canyon areas. Areas #1–
3 (Figure 4) are defined in Table 7 and
will be closed to use of the acoustic
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source year-round. Although they may
be protective of additional species (e.g.,
Kogia spp.), Area #1 is expected to be
particularly beneficial for beaked
whales and Areas #2–3 are expected to
be particularly beneficial for both
beaked whales and sperm whales;
• Shelf break off Cape Hatteras and to
the north (‘‘Hatteras and North’’),
including slope waters around ‘‘The
Point.’’ Area #4 is defined in Table 7
and will be closed to use of the acoustic
source from January through March.
Although this closure is expected to be
beneficial for a diverse species
assemblage, Area #4 is expected to be
particularly beneficial for beaked
whales, sperm whales, and pilot whales.
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BILLING CODE 3510–22–C
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Figure 4. Time-Area Restrictions.
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TABLE 7—BOUNDARIES OF TIME-AREA
RESTRICTIONS DEPICTED IN FIGURE 4
Area
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1
1
1
1
1
1
1
1
1
2
2
2
2
3
3
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3
3
3
3
4
4
4
4
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4
4
4
4
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4
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4
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Latitude
33°31′16″
33°10′05″
33°11′23″
33°43′34″
33°59′43″
34°15′10″
34°14′02″
34°03′33″
33°53′00″
34°13′21″
34°00′07″
34°38′40″
34°53′24″
36°41′17″
36°43′20″
36°55′20″
37°52′21″
37°43′54″
37°09′52″
36°52′01″
37°08′30″
36°15′12″
35°53′14″
34°23′07″
33°47′37″
33°48′31″
34°23′57″
35°22′29″
36°32′31″
37°05′39″
37°27′53″
38°23′15″
38°11′17″
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
Longitude
72°52′07″
72°59′59″
73°19′36″
73°17′43″
73°10′16″
72°55′37″
72°36′00″
72°37′27″
72°44′31″
74°07′33″
74°26′41″
75°05′52″
74°51′11″
71°25′47″
72°13′25″
72°26′18″
72°22′31″
72°00′40″
72°04′31″
71°24′31″
74°01′42″
73°48′37″
73°49′02″
75°21′33″
75°27′25″
75°52′58″
75°52′50″
74°51′50″
74°49′31″
74°45′37″
74°32′40″
73°45′06″
73°06′36″
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
Vessel Strike Avoidance
These measures apply to all vessels
associated with the planned survey
activity (e.g., source vessels, chase
vessels, supply vessels); however, we
note that these requirements do not
apply in any case where compliance
would create an imminent and serious
threat to a person or vessel or to the
extent that a vessel is restricted in its
ability to maneuver and, because of the
restriction, cannot comply. These
measures include the following:
1. Vessel operators and crews must
maintain a vigilant watch for all marine
mammals and slow down, stop their
vessel, or alter course, as appropriate
and regardless of vessel size, to avoid
striking any marine mammal. A single
marine mammal at the surface may
indicate the presence of submerged
animals in the vicinity of the vessel;
therefore, precautionary measures
should be exercised when an animal is
observed. A visual observer aboard the
vessel must monitor a vessel strike
avoidance zone around the vessel
(specific distances detailed below), to
ensure the potential for strike is
minimized. Visual observers monitoring
the vessel strike avoidance zone can be
either third-party observers or crew
members, but crew members
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responsible for these duties must be
provided sufficient training to
distinguish marine mammals from other
phenomena and broadly to identify a
marine mammal to broad taxonomic
group (i.e., as a right whale, other whale,
or other marine mammal). In this
context, ‘‘other whales’’ includes sperm
whales and all baleen whales other than
right whales;
2. All vessels, regardless of size, must
observe the 10 kn speed restriction in
specific areas designated for the
protection of North Atlantic right
whales: Any DMAs when in effect, the
Mid-Atlantic SMAs (from November 1
through April 30), and critical habitat
and the Southeast SMA (from November
15 through April 15). See
www.fisheries.noaa.gov/national/
endangered-species-conservation/
reducing-ship-strikes-north-atlanticright-whales for more information on
these areas;
3. Vessel speeds must also be reduced
to 10 kn or less when mother/calf pairs,
pods, or large assemblages of any
marine mammal are observed near a
vessel;
4. All vessels must maintain a
minimum separation distance of 500 m
from right whales. If a whale is observed
but cannot be confirmed as a species
other than a right whale, the vessel
operator must assume that it is a right
whale and take appropriate action;
5. All vessels must maintain a
minimum separation distance of 100 m
from sperm whales and all other baleen
whales;
6. All vessels must attempt to
maintain a minimum separation
distance of 50 m from all other marine
mammals, with an exception made for
those animals that approach the vessel;
and
7. When marine mammals are sighted
while a vessel is underway, the vessel
should take action as necessary to avoid
violating the relevant separation
distance (e.g., attempt to remain parallel
to the animal’s course, avoid excessive
speed or abrupt changes in direction
until the animal has left the area). If
marine mammals are sighted within the
relevant separation distance, the vessel
should reduce speed and shift the
engine to neutral, not engaging the
engines until animals are clear of the
area. This recommendation does not
apply to any vessel towing gear.
General Measures
All vessels associated with survey
activity (e.g., source vessels, chase
vessels, supply vessels) must have a
functioning Automatic Identification
System (AIS) onboard and operating at
all times, regardless of whether AIS
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would otherwise be required. Vessel
names and call signs must be provided
to NMFS, and applicants must notify
NMFS when survey vessels are
operating.
We have carefully evaluated the suite
of mitigation measures described here
and considered a range of other
measures in the context of ensuring that
we prescribe the means of effecting the
least practicable adverse impact on the
affected marine mammal species and
stocks and their habitat. Based on our
evaluation of these measures, we have
determined that the required mitigation
measures provide the means of effecting
the least practicable adverse impact on
marine mammal species or stocks and
their habitat, paying particular attention
to rookeries, mating grounds, and areas
of similar significance.
Monitoring and Reporting
In order to issue an IHA for an
activity, Section 101(a)(5)(D) of the
MMPA states that NMFS must set forth
requirements pertaining to the
monitoring and reporting of the
authorized taking. NMFS’s MMPA
implementing regulations further
describe the information that an
applicant should provide when
requesting an authorization (50 CFR
216.104(a)(13)), including the means of
accomplishing the necessary monitoring
and reporting that will result in
increased knowledge of the species and
the level of taking or impacts on
populations of marine mammals.
Effective reporting is critical both to
compliance as well as ensuring that the
most value is obtained from the required
monitoring.
Monitoring and reporting
requirements prescribed by NMFS
should contribute to improved
understanding of one or more of the
following:
• Occurrence of marine mammal
species in action area (e.g., presence,
abundance, distribution, density);
• Nature, scope, or context of likely
marine mammal exposure to potential
stressors/impacts (individual or
cumulative, acute or chronic), through
better understanding of: (1) Action or
environment (e.g., source
characterization, propagation, ambient
noise); (2) affected species (e.g., life
history, dive patterns); (3) co-occurrence
of marine mammal species with the
action; or (4) biological or behavioral
context of exposure (e.g., age, calving or
feeding areas);
• Individual marine mammal
responses (behavioral or physiological)
to acoustic stressors (acute, chronic, or
cumulative), other stressors, or
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cumulative impacts from multiple
stressors;
• How anticipated responses to
stressors impact either: (1) Long-term
fitness and survival of individual
marine mammals; or (2) populations,
species, or stocks;
• Effects on marine mammal habitat
(e.g., marine mammal prey species,
acoustic habitat, or important physical
components of marine mammal habitat);
and
• Mitigation and monitoring
effectiveness.
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Changes From the Notice of Proposed
IHAs
Here we summarize substantive
changes to monitoring and reporting
requirements from our Notice of
Proposed IHAs. All changes were made
on the basis of review of public
comments received and/or review of
new information.
• As described in our Notice of
Proposed IHAs, we preliminarily
reached small numbers findings for
some species on the basis of the
proposed limitation of authorized take
to approximately one-third of the
abundance estimate deemed at the time
to be most appropriate. In order to
ensure that IHA-holders would not
exceed this cap without limiting the
planned survey activity, we proposed to
require interim reporting in which IHAholders would report all observations of
marine mammals as well as corrected
numbers of marine mammals ‘‘taken.’’
We received information from several
commenters—including several of the
applicants—strongly indicating that
such a de facto limitation, coupled with
a novel reporting requirement, was
impracticable. In summary, commenters
noted that such surveys are multimillion dollar endeavors and stated that
the surveys would simply not be
conducted rather than commit such
costs to the survey in the face of
significant uncertainty as to whether the
survey might be suddenly shut down as
a result of reaching a pre-determined
cap on the basis of novel modeling of
‘‘corrected’’ takes. We also received
many comments indicating that our
small numbers analyses were flawed
and, as described in detail later in this
notice (see ‘‘Small Numbers Analyses’’)
we reconsidered the available
information and re-evaluated our
analyses in response to these comments.
As a result of our revised small numbers
analyses, such a cap coupled with
reporting scheme is not necessary.
Further, we agree with commenters that
the proposal presented significant
practicability concerns. Therefore, the
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proposed ‘‘interim’’ reporting
requirement is eliminated.
• Separately, while we recognize the
importance of producing the most
accurate estimates of actual take
possible, we agree that the proposed
approach to correcting observations to
produce estimates of actual takes was
(1) not the best available approach; (2)
is novel in that it has not been
previously required of applicants
conducting similar activities; and (3)
may not be appropriate for application
to observations conducted from working
source vessels. We have adopted a
different approach to performing these
‘‘corrections,’’ as recommended through
comment from the Marine Mammal
Commission, but in this case we will
perform these corrections upon
submission of reports from IHA-holders
and evaluate the appropriateness of this
approach and the validity of the results
prior to requiring it for future IHAs.
• As a result of concerns expressed
through public comment, we have
revised requirements relating to
reporting of injured or dead marine
mammals and have added newly crafted
requirements relating to actions that
should be taken in response to stranding
events in certain circumstances.
Monitoring requirements are the same
for all applicants, and a single
discussion is provided here.
PSO Eligibility and Qualifications
All PSO resumes must be submitted
to NMFS and PSOs must be approved
by NMFS after a review of their
qualifications. These qualifications
include whether the individual has
successfully completed the necessary
training (see ‘‘Training,’’ below) and, if
relevant, whether the individual has the
requisite experience (and is in good
standing). PSOs should provide a
current resume and information related
to PSO training; submitted resumes
should not include superfluous
information. Information related to PSO
training should include (1) a course
information packet that includes the
name and qualifications (e.g.,
experience, training, or education) of
the instructor(s), the course outline or
syllabus, and course reference material;
and (2) a document stating the PSO’s
successful completion of the course.
PSOs must be trained biologists, with
the following minimum qualifications:
• A bachelor’s degree from an
accredited college or university with a
major in one of the natural sciences and
a minimum of 30 semester hours or
equivalent in the biological sciences and
at least one undergraduate course in
math or statistics;
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• Experience and ability to conduct
field observations and collect data
according to assigned protocols (may
include academic experience) and
experience with data entry on
computers;
• Visual acuity in both eyes
(correction is permissible) sufficient for
discernment of moving targets at the
water’s surface with ability to estimate
target size and distance; use of
binoculars may be necessary to correctly
identify the target (required for visual
PSOs only);
• Experience or training in the field
identification of marine mammals,
including the identification of behaviors
(required for visual PSOs only);
• Sufficient training, orientation, or
experience with the survey operation to
ensure personal safety during
observations;
• Writing skills sufficient to prepare a
report of observations (e.g., description,
summary, interpretation, analysis)
including but not limited to the number
and species of marine mammals
observed; marine mammal behavior;
and descriptions of activity conducted
and implementation of mitigation;
• Ability to communicate orally, by
radio or in person, with survey
personnel to provide real-time
information on marine mammals
detected in the area as necessary; and
• Successful completion of relevant
training (described below), including
completion of all required coursework
and passing (80 percent or greater) a
written and/or oral examination
developed for the training program.
The educational requirements may be
waived if the PSO has acquired the
relevant skills through alternate
experience. Requests for such a waiver
must include written justification, and
prospective PSOs granted waivers must
satisfy training requirements described
below. Alternate experience that may be
considered includes, but is not limited
to, the following:
• Secondary education and/or
experience comparable to PSO duties;
• Previous work experience
conducting academic, commercial, or
government-sponsored marine mammal
surveys; and
• Previous work experience as a PSO;
the PSO should demonstrate good
standing and consistently good
performance of PSO duties.
Training—NMFS does not currently
approve specific training programs;
however, acceptable training may
include training previously approved by
BSEE, or training that adheres generally
to the recommendations provided by
‘‘National Standards for a Protected
Species Observer and Data Management
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Program: A Model Using Geological and
Geophysical Surveys’’ (Baker et al.,
2013). Those recommendations include
the following topics for training
programs:
• Life at sea, duties, and authorities;
• Ethics, conflicts of interest,
standards of conduct, and data
confidentiality;
• Offshore survival and safety
training;
• Overview of oil and gas activities
(including geophysical data acquisition
operations, theory, and principles) and
types of relevant sound source
technology and equipment;
• Overview of the MMPA and ESA as
they relate to protection of marine
mammals;
• Mitigation, monitoring, and
reporting requirements as they pertain
to geophysical surveys;
• Marine mammal identification,
biology and behavior;
• Background on underwater sound;
• Visual surveying protocols, distance
calculations and determination, cues,
and search methods for locating and
tracking different marine mammal
species (visual PSOs only);
• Optimized deployment and
configuration of PAM equipment to
ensure effective detections of cetaceans
for mitigation purposes (PAM operators
only);
• Detection and identification of
vocalizing species or cetacean groups
(PAM operators only);
• Measuring distance and bearing of
vocalizing cetaceans while accounting
for vessel movement (PAM operators
only);
• Data recording and protocols,
including standard forms and reports,
determining range, distance, direction,
and bearing of marine mammals and
vessels; recording GPS location
coordinates, weather conditions,
Beaufort wind force and sea state, etc.;
• Proficiency with relevant software
tools;
• Field communication/support with
appropriate personnel, and using
communication devices (e.g., two-way
radios, satellite phones, internet, email,
facsimile);
• Reporting of violations,
noncompliance, and coercion; and
• Conflict resolution.
PAM operators should regularly
refresh their detection skills through
practice with simulation-modeling
software, and should keep up to date
with training on the latest software/
hardware advances.
Visual Monitoring
The lead PSO is responsible for
establishing and maintaining clear lines
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of communication with vessel crew. The
vessel operator shall work with the lead
PSO to accomplish this and shall ensure
any necessary briefings are provided for
vessel crew to understand mitigation
requirements and protocols. While on
duty, PSOs will continually scan the
water surface in all directions around
the acoustic source and vessel for
presence of marine mammals, using a
combination of the naked eye and highquality binoculars, from optimum
vantage points for unimpaired visual
observations with minimum
distractions. PSOs will collect
observational data for all marine
mammals observed, regardless of
distance from the vessel, including
species, group size, presence of calves,
distance from vessel and direction of
travel, and any observed behavior
(including an assessment of behavioral
responses to survey activity). Upon
observation of marine mammal(s), a
PSO will record the observation and
monitor the animal’s position (including
latitude/longitude of the vessel and
relative bearing and estimated distance
to the animal) until the animal dives or
moves out of visual range of the
observer, and a PSO will continue to
observe the area to watch for the animal
to resurface or for additional animals
that may surface in the area. PSOs will
also record environmental conditions at
the beginning and end of the
observation period and at the time of
any observations, as well as whenever
conditions change significantly in the
judgment of the PSO on duty.
The vessel operator must provide
bigeye binoculars (e.g., 25 x 150; 2.7
view angle; individual ocular focus;
height control) of appropriate quality
(e.g., Fujinon or equivalent) solely for
PSO use. These should be pedestalmounted on the deck at the most
appropriate vantage point that provides
for optimal sea surface observation, PSO
safety, and safe operation of the vessel.
The operator must also provide a nightvision device suited for the marine
environment for use during nighttime
ramp-up pre-clearance, at the discretion
of the PSOs. NVDs may include night
vision binoculars or monocular or
forward-looking infrared device (e.g.,
Exelis PVS–7 night vision goggles; Night
Optics D–300 night vision monocular;
FLIR M324XP thermal imaging camera
or equivalents). At minimum, the device
should feature automatic brightness and
gain control, bright light protection,
infrared illumination, and optics suited
for low-light situations. Other required
equipment, which should be made
available to PSOs by the third-party
observer provider, includes reticle
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binoculars (e.g., 7 x 50) of appropriate
quality (e.g., Fujinon or equivalent),
GPS, digital single-lens reflex camera of
appropriate quality (e.g., Canon or
equivalent), compass, and any other
tools necessary to adequately perform
the tasks described above, including
accurate determination of distance and
bearing to observed marine mammals.
Individuals implementing the
monitoring protocol will assess its
effectiveness using an adaptive
approach. Monitoring biologists will use
their best professional judgment
throughout implementation and seek
improvements to these methods when
deemed appropriate. Specifically,
implementation of shutdown
requirements will be made on the basis
of the PSO’s best professional judgment.
While PSOs should not insert undue
‘‘precaution’’ into decision-making, it is
expected that PSOs may call for
mitigation action on the basis of
reasonable certainty regarding the need
for such action, as informed by
professional judgment. Any
modifications to protocol will be
coordinated between NMFS and the
applicant.
Acoustic Monitoring
Monitoring of a towed PAM system is
required at all times, from 30 minutes
prior to ramp-up and throughout all use
of the acoustic source. Towed PAM
systems generally consist of hardware
(e.g., hydrophone array, cables) and
software (e.g., data processing and
monitoring system). Some type of
automated detection software must be
used; while not required, we
recommend use of industry standard
software (e.g., PAMguard, which is open
source). Hydrophone signals are
processed for output to the PAM
operator with software designed to
detect marine mammal vocalizations.
Current PAM technology has some
limitations (e.g., limited directional
capabilities and detection range,
masking of signals due to noise from the
vessel, source, and/or flow, localization)
and there are no formal guidelines
currently in place regarding
specifications for hardware, software, or
operator training requirements.
Our requirement to use PAM refers to
the use of calibrated hydrophone arrays
with full system redundancy to detect,
identify, and estimate distance and
bearing to vocalizing cetaceans, to the
extent possible. With regard to
calibration, the PAM system should
have at least one calibrated hydrophone,
sufficient for determining whether
background noise levels on the towed
PAM system are sufficiently low to meet
performance expectations. Additionally,
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if multiple hydrophone types occur in a
system (i.e., monitor different
bandwidths), then one hydrophone from
each such type should be calibrated,
and whenever sets of hydrophones (of
the same type) are sufficiently spatially
separated such that they would be
expected to experience ambient noise
environments that differ by 6 dB or
more across any integrated species
cluster bandwidth, then at least one
hydrophone from each set should be
calibrated. The arrays should
incorporate appropriate hydrophone
elements (1 Hz to 180 kHz range) and
sound data acquisition card technology
for sampling relevant frequencies (i.e.,
to 360 kHz). This hardware should be
coupled with appropriate software to
aid monitoring and listening by a PAM
operator skilled in bioacoustics analysis
and computer system specifications
capable of running appropriate software.
Applicant-specific PAM plans were
made available for review either in
individual applications or as separate
documents online at:
www.fisheries.noaa.gov/action/
incidental-take-authorization-oil-andgas-industry-geophysical-surveyactivity-atlantic. As recommended by
Thode et al. (2017), PAM plans should,
at minimum, adequately address and
describe (1) the hardware and software
planned for use, including a hardware
performance diagram demonstrating
that the sensitivity and dynamic range
of the hardware is appropriate for the
operation; (2) deployment methodology,
including target depth/tow distance; (3)
definitions of expected operational
conditions, used to summarize
background noise statistics; (4)
proposed detection-classificationlocalization methodology, including
anticipated species clusters (using a
cluster definition table), target
minimum detection range for each
cluster, and the proposed localization
method for each cluster; (5) operation
plans, including the background noise
sampling schedule; (6) array design
considerations for noise abatement; and
(7) cluster-specific details regarding
which real-time displays and automated
detectors the operator would monitor.
In coordination with vessel crew, the
lead PAM operator will be responsible
for deployment, retrieval, and testing
and optimization of the hydrophone
array. While on duty, the PAM operator
must diligently listen to received signals
and/or monitoring display screens in
order to detect vocalizing cetaceans,
except as required to attend to PAM
equipment. The PAM operator must use
appropriate sample analysis and
filtering techniques and, as described
below, must report all cetacean
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detections. While not required prior to
development of formal standards for
PAM use, we recommend that vessel
self-noise assessments are undertaken
during mobilization in order to optimize
PAM array configuration according to
the specific noise characteristics of the
vessel and equipment involved, and to
refine expectations for distance/bearing
estimations for cetacean species during
the survey. Copies of any vessel selfnoise assessment reports must be
included with the summary trip report.
Data Collection
PSOs must use standardized data
forms, whether hard copy or electronic.
PSOs will record detailed information
about any implementation of mitigation
requirements, including the distance of
animals to the acoustic source and
description of specific actions that
ensued, the behavior of the animal(s),
any observed changes in behavior before
and after implementation of mitigation,
and if shutdown was implemented, the
length of time before any subsequent
ramp-up of the acoustic source to
resume survey. If required mitigation
was not implemented, PSOs should
submit a description of the
circumstances. We require that, at a
minimum, the following information be
reported:
• Vessel names (source vessel and
other vessels associated with survey)
and call signs;
• PSO names and affiliations;
• Dates of departures and returns to
port with port name;
• Dates and times (Greenwich Mean
Time) of survey effort and times
corresponding with PSO effort;
• Vessel location (latitude/longitude)
when survey effort begins and ends;
vessel location at beginning and end of
visual PSO duty shifts;
• Vessel heading and speed at
beginning and end of visual PSO duty
shifts and upon any line change;
• Environmental conditions while on
visual survey (at beginning and end of
PSO shift and whenever conditions
change significantly), including wind
speed and direction, Beaufort sea state,
Beaufort wind force, swell height,
weather conditions, cloud cover, sun
glare, and overall visibility to the
horizon;
• Factors that may be contributing to
impaired observations during each PSO
shift change or as needed as
environmental conditions change (e.g.,
vessel traffic, equipment malfunctions);
• Survey activity information, such as
acoustic source power output while in
operation, number and volume of
airguns operating in the array, tow
depth of the array, and any other notes
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of significance (i.e., pre-ramp-up survey,
ramp-up, shutdown, testing, shooting,
ramp-up completion, end of operations,
streamers, etc.);
• If a marine mammal is sighted, the
following information should be
recorded:
Æ Watch status (sighting made by
PSO on/off effort, opportunistic, crew,
alternate vessel/platform);
Æ PSO who sighted the animal;
Æ Time of sighting;
Æ Vessel location at time of sighting;
Æ Water depth;
Æ Direction of vessel’s travel
(compass direction);
Æ Direction of animal’s travel relative
to the vessel;
Æ Pace of the animal;
Æ Estimated distance to the animal
and its heading relative to vessel at
initial sighting;
Æ Identification of the animal (e.g.,
genus/species, lowest possible
taxonomic level, or unidentified); also
note the composition of the group if
there is a mix of species;
Æ Estimated number of animals (high/
low/best);
Æ Estimated number of animals by
cohort (adults, yearlings, juveniles,
calves, group composition, etc.);
Æ Description (as many
distinguishing features as possible of
each individual seen, including length,
shape, color, pattern, scars or markings,
shape and size of dorsal fin, shape of
head, and blow characteristics);
Æ Detailed behavior observations
(e.g., number of blows, number of
surfaces, breaching, spyhopping, diving,
feeding, traveling; as explicit and
detailed as possible; note any observed
changes in behavior);
Æ Animal’s closest point of approach
(CPA) and/or closest distance from the
acoustic source;
Æ Platform activity at time of sighting
(e.g., deploying, recovering, testing,
shooting, data acquisition, other); and
Æ Description of any actions
implemented in response to the sighting
(e.g., delays, shutdown, ramp-up, speed
or course alteration, etc.); time and
location of the action should also be
recorded;
• If a marine mammal is detected
while using the PAM system, the
following information should be
recorded:
Æ An acoustic encounter
identification number, and whether the
detection was linked with a visual
sighting;
Æ Time when first and last heard;
Æ Types and nature of sounds heard
(e.g., clicks, whistles, creaks, burst
pulses, continuous, sporadic, strength of
signal, etc.); and
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Æ Any additional information
recorded such as water depth of the
hydrophone array, bearing of the animal
to the vessel (if determinable), species
or taxonomic group (if determinable),
spectrogram screenshot, and any other
notable information.
Reporting
Applicants must submit a draft
comprehensive report to NMFS within
90 days of the completion of survey
effort or expiration of the IHA
(whichever comes first), and must
include all information described above
under ‘‘Data Collection.’’ If a subsequent
IHA request is planned, a report must be
submitted a minimum of 75 days prior
to the requested date of issuance for the
subsequent IHA. The report must
describe the operations conducted and
sightings of marine mammals near the
operations; provide full documentation
of methods, results, and interpretation
pertaining to all monitoring; summarize
the dates and locations of survey
operations, and all marine mammal
sightings (dates, times, locations,
activities, associated survey activities);
and provide information regarding
locations where the acoustic source was
used. The IHA-holder shall provide georeferenced time-stamped vessel
tracklines for all time periods in which
airguns (full array or single) were
operating. Tracklines should include
points recording any change in airgun
status (e.g., when the airguns began
operating, when they were turned off).
GIS files shall be provided in ESRI
shapefile format and include the UTC
date and time, latitude in decimal
degrees, and longitude in decimal
degrees. All coordinates should be
referenced to the WGS84 geographic
coordinate system. In addition to the
report, all raw observational data shall
be made available to NMFS. This report
must also include a validation
document concerning the use of PAM,
which should include necessary noise
validation diagrams and demonstrate
whether background noise levels on the
PAM deployment limited achievement
of the planned detection goals. The draft
report must be accompanied by a
certification from the lead PSO as to the
accuracy of the report. A final report
must be submitted within 30 days
following resolution of any NMFS
comments on the draft report.
In association with the final
comprehensive reports, NMFS will
calculate and make available estimates
of the number of takes based on the
observations and in consideration of the
detectability of the marine mammal
species observed (as described below).
PSO effort, survey details, and sightings
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data should be recorded continuously
during surveys and reports prepared
each day during which survey effort is
conducted. As described below, NMFS
will use these observational data to
calculate corrected numbers of marine
mammals taken.
There are multiple reasons why
marine mammals may be present and
yet be undetected by observers. Animals
are missed because they are underwater
(availability bias) or because they are
available to be seen, but are missed by
observers (perception and detection
biases) (e.g., Marsh and Sinclair, 1989).
Negative bias on perception or detection
of an available animal may result from
environmental conditions, limitations
inherent to the observation platform, or
observer ability. In this case, we do not
have prior knowledge of any potential
negative bias on detection probability
due to observation platform or observer
ability. Therefore, observational data
corrections must be made with respect
to assumed species-specific detection
probability as evaluated through
consideration of environmental factors
(e.g., f(0)). In order to make these
corrections, we plan to use a method
recommended by the Marine Mammal
Commission (MMC) for estimating the
number of cetaceans in the vicinity of
the surveys based on the number of
groups detected. This method is
described in full in the MMC’s comment
letter for these actions, which is
available online at:
www.fisheries.noaa.gov/action/
incidental-take-authorization-oil-andgas-industry-geophysical-surveyactivity-atlantic.
Reporting Injured or Dead Marine
Mammals
Discovery of Injured or Dead Marine
Mammal—In the event that personnel
involved in the survey activities covered
by the authorization discover an injured
or dead marine mammal, the IHAholder shall report the incident to the
Office of Protected Resources (OPR),
NMFS and to regional stranding
coordinators as soon as feasible. The
report must include the following
information:
• Time, date, and location (latitude/
longitude) of the first discovery (and
updated location information if known
and applicable);
• Species identification (if known) or
description of the animal(s) involved;
• Condition of the animal(s)
(including carcass condition if the
animal is dead);
• Observed behaviors of the
animal(s), if alive;
• If available, photographs or video
footage of the animal(s); and
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• General circumstances under which
the animal was discovered.
Vessel Strike—In the event of a ship
strike of a marine mammal by any vessel
involved in the activities covered by the
authorization, the IHA-holder shall
report the incident to OPR, NMFS and
to regional stranding coordinators as
soon as feasible. The report must
include the following information:
• Time, date, and location (latitude/
longitude) of the incident;
• Species identification (if known) or
description of the animal(s) involved;
• Vessel’s speed during and leading
up to the incident;
• Vessel’s course/heading and what
operations were being conducted (if
applicable);
• Status of all sound sources in use;
• Description of avoidance measures/
requirements that were in place at the
time of the strike and what additional
measures were taken, if any, to avoid
strike;
• Environmental conditions (e.g.,
wind speed and direction, Beaufort sea
state, cloud cover, visibility)
immediately preceding the strike;
• Estimated size and length of animal
that was struck;
• Description of the behavior of the
marine mammal immediately preceding
and following the strike;
• If available, description of the
presence and behavior of any other
marine mammals immediately
preceding the strike;
• Estimated fate of the animal (e.g.,
dead, injured but alive, injured and
moving, blood or tissue observed in the
water, status unknown, disappeared);
and
• To the extent practicable,
photographs or video footage of the
animal(s).
Actions To Minimize Additional Harm
to Live-Stranded (or Milling) Marine
Mammals
In the event of a live stranding (or
near-shore atypical milling) event
within 50 km of the survey operations,
where the NMFS stranding network is
engaged in herding or other
interventions to return animals to the
water, the Director of OPR, NMFS (or
designee) will advise the IHA-holder of
the need to implement shutdown
procedures for all active acoustic
sources operating within 50 km of the
stranding. Shutdown procedures for live
stranding or milling marine mammals
include the following:
• If at any time, the marine mammals
die or are euthanized, or if herding/
intervention efforts are stopped, the
Director of OPR, NMFS (or designee)
will advise the IHA-holder that the
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shutdown around the animals’ location
is no longer needed.
• Otherwise, shutdown procedures
will remain in effect until the Director
of OPR, NMFS (or designee) determines
and advises the IHA-holder that all live
animals involved have left the area
(either of their own volition or following
an intervention).
• If further observations of the marine
mammals indicate the potential for restranding, additional coordination with
the IHA-holder will be required to
determine what measures are necessary
to minimize that likelihood (e.g.,
extending the shutdown or moving
operations farther away) and to
implement those measures as
appropriate.
Shutdown procedures are not related
to the investigation of the cause of the
stranding and their implementation is
not intended to imply that the specified
activity is the cause of the stranding.
Rather, shutdown procedures are
intended to protect marine mammals
exhibiting indicators of distress by
minimizing their exposure to possible
additional stressors, regardless of the
factors that contributed to the stranding.
Additional Information Requests—If
NMFS determines that the
circumstances of any marine mammal
stranding found in the vicinity of the
activity suggest investigation of the
association with survey activities is
warranted (example circumstances
noted below), and an investigation into
the stranding is being pursued, NMFS
will submit a written request to the IHAholder indicating that the following
initial available information must be
provided as soon as possible, but no
later than 7 business days after the
request for information.
• Status of all sound source use in the
48 hours preceding the estimated time
of stranding and within 50 km of the
discovery/notification of the stranding
by NMFS; and
• If available, description of the
behavior of any marine mammal(s)
observed preceding (i.e., within 48
hours and 50 km) and immediately after
the discovery of the stranding.
Examples of circumstances that could
trigger the additional information
request include, but are not limited to,
the following:
• Atypical nearshore milling events
of live cetaceans;
• Mass strandings of cetaceans (two
or more individuals, not including cow/
calf pairs);
• Beaked whale strandings;
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• Necropsies with findings of
pathologies that are unusual for the
species or area; or
• Stranded animals with findings
consistent with blast trauma.
In the event that the investigation is
still inconclusive, the investigation of
the association of the survey activities is
still warranted, and the investigation is
still being pursued, NMFS may provide
additional information requests, in
writing, regarding the nature and
location of survey operations prior to
the time period above.
Negligible Impact Analyses and
Determinations
NMFS has defined negligible impact
as an impact resulting from the
specified activity that cannot be
reasonably expected to, and is not
reasonably likely to, adversely affect the
species or stock through effects on
annual rates of recruitment or survival
(50 CFR 216.103). A negligible impact
finding is based on the lack of likely
adverse effects on annual rates of
recruitment or survival (i.e., populationlevel effects). An estimate of the number
of takes alone is not enough information
on which to base a negligible impact
determination. In addition to
considering estimates of the number of
marine mammals that might be ‘‘taken’’
by mortality, serious injury, and Level A
or Level B harassment, we consider
other factors, such as the type of take,
the likely nature of any behavioral
responses (e.g., intensity, duration), the
context of any such responses (e.g.,
critical reproductive time or location,
migration), as well as effects on habitat,
and the likely effectiveness of
mitigation. We also assess the number,
intensity, and context of estimated takes
by evaluating this information relative
to population status. Consistent with the
1989 preamble for NMFS’s
implementing regulations (54 FR 40338;
September 29, 1989), the impacts from
other past and ongoing anthropogenic
activities are incorporated into these
analyses via their impacts on the
environmental baseline (e.g., as
reflected in the regulatory status of the
species, population size and growth rate
where known, ongoing sources of
human-caused mortality).
We first provide a generic description
of our approach to the negligible impact
analyses for these actions, which
incorporates elements of the assessment
methodology described by Wood et al.
(2012), before providing applicantspecific analysis. For each potential
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activity-related stressor, we consider the
potential effects to marine mammals
and the likely significance of those
effects to the species or stock as a
whole. Potential risk due to vessel
collision and related mitigation
measures as well as potential risk due
to entanglement and contaminant spills
were addressed under ‘‘Mitigation’’ and
in the ‘‘Potential Effects of the Specified
Activity on Marine Mammals’’ section
of our Notice of Proposed IHAs and are
not discussed further, as there are
minimal risks expected from these
potential stressors.
Our analyses incorporate a simple
matrix assessment approach to generate
relative impact ratings that couple
potential magnitude of effect on a stock
and likely consequences of those effects
for individuals, given biologically
relevant information (e.g., compensatory
ability). These impact ratings are then
combined with consideration of
contextual information, such as the
status of the stock or species, in
conjunction with our required
mitigation strategy, to ultimately inform
our negligible impact determinations.
Figure 5 provides an overview of this
framework. Elements of this approach
are subjective and relative within the
context of these particular actions and,
overall, these analyses necessarily
require the application of professional
judgment. As shown in Figure 5, it is
important to be clear that the ‘‘impact
rating’’ does not equate to the ultimate
assessment of impact to the species or
stock, i.e., the negligible impact
determination. The ‘‘impact rating’’ is
considered in conjunction with relevant
contextual factors to inform the overall
assessment of impact to the species or
stock.
Changes From the Notice of Proposed
IHAs
Following review of public
comments, we largely retain the
negligible impact analysis framework
and specific analyses described in our
Notice of Proposed IHAs. However, we
have made several adjustments on the
basis of our review.
• As a result of our revised take
estimates (‘‘Estimated Take’’) and
reconsideration of available information
(‘‘Description of Marine Mammals in the
Area of the Specified Activities’’ and
‘‘Small Numbers Analyses’’), the
amount of take has changed for some
species for some applicants. In some
cases, this leads to a change in overall
magnitude rating.
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• We agree with commenters who
pointed out that a de minimis
magnitude rating should not render
consequences for individuals irrelevant
to the impact rating. Rather, the
assessed level of consequences pairs
with the magnitude rating to produce
the overall impact rating. In our
preliminary negligible impact analyses,
for example, mysticete whales with a de
minimis amount of take were assigned
an overall de minimis impact rating, as
consequences were considered not
applicable in cases where a de minimis
magnitude rating was assigned.
However, the assessed level of potential
consequences for individual mysticetes
of ‘‘medium’’—which is related to
inherent vulnerabilities of the taxon,
and is therefore not dependent on the
specific magnitude rating—would still
exist, regardless of the amount of take/
magnitude rating. Therefore, under our
revised approach, a mysticete whale
with a de minimis magnitude rating is
now assigned a low impact rating.
In order to reflect the change
described in the preceding paragraph,
we have adjusted the impact rating
scheme (Table 9). Whereas before a de
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minimis magnitude rating previously
resulted in a de minimis impact rating
regardless of assessed potential
consequences to individuals, a de
minimis magnitude rating now leads to
a de minimis impact rating only if the
assessed consequences are low; the de
minimis impact rating with medium
assessed potential consequences for
individuals would lead to an impact
rating of low.
Impact Rating
Magnitude—We consider magnitude
of effect as a semi-quantitative
evaluation of measurable factors
presented as relative ratings that address
the spatiotemporal extent of expected
effects to a species or stock and their
habitat. Magnitude ratings are
developed as a combination of
measurable factors: The amount of take,
the spatial extent of the effects in the
context of the species range, and the
duration of effects.
Amount of Take
We consider authorized take by Level
B harassment of less than five percent
of the most appropriate population
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63363
abundance to be de minimis, while
authorized Level B harassment taking
between 5–15 percent is low. A
moderate amount of authorized taking
by Level B harassment would be from
15–25 percent, and high above 25
percent.
Although we do not define
quantitative metrics relating to amount
of potential take by Level A harassment,
for all applicant companies the expected
potential for Level A harassment and,
therefore, the authorized taking, is very
low (Table 6). For these specified
activities, as described in detail in
‘‘Estimated Take,’’ the best available
science indicates that there is no
reasonable potential for Level A
harassment of mid-frequency cetaceans,
while there is only limited potential for
Level A harassment of low-frequency
cetaceans when considering that Level
A harassment is dependent on
accumulation of energy from a mobile
acoustic source. Similarly, estimated
takes by Level A harassment are very
low for all high-frequency cetacean
species.
Overall, while these limited incidents
of Level A harassment would result in
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permanent hearing loss, the effects of
such hearing loss are expected to be
minor for several reasons. First, the
acoustic thresholds used in our
exposure analysis represent thresholds
for the onset of PTS (i.e., the minimum
sound levels at which minor PTS could
occur; NMFS, 2018), not thresholds for
moderate or severe PTS. In order to
determine the likelihood of moderate or
severe PTS, one needs to consider the
actual level of exposure (for highfrequency cetaceans) or, for lowfrequency cetaceans, the duration of
exposure at the PTS onset threshold
distances from the airgun arrays or
closer. High-frequency cetaceans that
may be present (i.e., harbor porpoise
and Kogia spp.) are known to be
behaviorally sensitive to acoustic
disturbance and are unlikely to
approach source vessels at distances
that might lead to more severe PTS.
Similarly, mysticete whales are known
to display avoidance behaviors in the
vicinity of airgun surveys (e.g., Ellison
et al., 2016) and, when considered in
conjunction with the estimated
distances to the thresholds for the onset
of PTS (Table 5), it is likely that such
PTS exposure would be brief and at or
near PTS onset levels. For example, a
recent study analyzing 16 years of PSO
data consisting of marine mammal
observations during seismic surveys in
waters off the United Kingdom found
that the median closest approach by fin
whales during active airgun use was
1,225 m (Stone et al., 2017), a distance
well beyond the PTS onset threshold
distances estimated for these specific
airgun arrays. The degree of PTS would
be further minimized through use of the
ramp-up procedure, which will alert
animals to the source prior to its
achieving full power, and through
shutdown requirements, which will not
necessarily prevent exposure but are
expected to reduce the intensity and
duration of exposure. Available data
suggest that such PTS would primarily
occur at frequencies where the majority
of the energy from airgun sounds occurs
(below 500 Hz). For high-frequency
cetaceans, any PTS would therefore
occur at frequencies well outside their
estimated range of maximum sensitivity.
For low-frequency cetaceans, these
frequencies overlap with the frequencies
used for communication and so may
interfere somewhat with their ability to
communicate, though still below the
estimated range of maximum sensitivity
for these species. The expected mild
PTS would not likely meaningfully
impact the affected high-frequency
cetaceans, and may have minor effects
on the ability of affected low-frequency
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cetaceans to hear conspecific calls and/
or other environmental cues. For all
applicants, the expected effects of Level
A harassment on all stocks to which
such take may occur is appropriately
considered de minimis.
Spatial Extent
Spatial extent relates to overlap of the
expected range of the affected stock
with the expected footprint of the
stressor. While we do not define
quantitative metrics relative to
assessment of spatial extent, a relatively
low impact is defined here as a
localized effect on the stock’s range, a
relatively moderate impact is defined as
a regional-scale effect (meaning that the
overlap between stressor and range was
partial), and a relatively high impact is
one in which the degree of overlap
between stressor and range is near total.
For a mobile activity occurring over a
relatively large, regional-scale area, this
categorization is made largely on the
basis of the stock range in relation to the
action area. For example, the harbor
porpoise is expected to occur almost
entirely outside of the planned survey
areas (Hayes et al., 2017; Roberts et al.,
2016) and therefore despite the large
extent of planned survey activity, the
spatial extent of potential stressor effect
would be low. A medium degree of
effect would be expected for a species
such as the Risso’s dolphin, which has
a distribution in shelf and slope waters
along the majority of the U.S. Atlantic
coast, and which also would be
expected to have greater abundance in
mid-Atlantic waters north of the survey
areas in the summer (Hayes et al.,
2018a; Roberts et al., 2016). This means
that the extent of potential stressor for
this species would at all times be
expected to have some overlap with a
portion of the stock, while some portion
(increasing in summer and fall months)
would at all times be outside the
stressor footprint. A higher degree of
impact with regard to spatial extent
would be expected for a species such as
the Clymene dolphin, which is expected
to have a generally more southerly
distribution (Waring et al., 2014;
Roberts et al., 2016) and thus more
nearly complete overlap with the
expected stressor footprint in the
specific geographic region.
In Tables 10–14 below, spatial extent
is presented as a range for certain
species with known migratory patterns.
We expect spatial extent (overlap of
stock range with planned survey area) to
be low for right whales from May
through October but moderate from
November through April, due to right
whale movements into southeastern
shelf waters in the winter for calving.
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The overlap is considered moderate
during winter because not all right
whales make this winter migration, and
those that do are largely found in
shallow waters where little survey effort
is planned (and when/where we
prescribe a spatial restriction that would
largely preclude any potential overlap
between right whales and effects of the
survey activities). Spatial extent for
humpback whales is expected to be low
for most of the year, but likely moderate
during winter, while spatial extent for
minke whales is likely low in summer,
moderate in spring and fall, and high in
winter. While we consider spatial extent
to be low year-round for fin whales,
their range overlap with the planned
survey area does vary across the seasons
and is closer to moderate in winter and
spring. We expect spatial extent for
common dolphins to be lower in fall but
generally moderate. Similarly, we
expect spatial extent for Risso’s
dolphins to be lower in summer but
generally moderate. Although survey
plans differ across applicants, all cover
large spatial scales that extend
throughout much of the specific
geographic region, and we do not expect
meaningful differences across surveys
with regard to spatial extent.
Temporal Extent
The temporal aspect of the stressor is
measured through consideration of
duration and frequency. Duration
describes how long the effects of the
stressor last. Temporal frequency may
range from continuous to isolated (may
occur one or two times), or may be
intermittent. We consider a temporary
effect lasting up to one month (prior to
the animal or habitat reverting to a
‘‘normal’’ condition) to be short-term,
whereas long-term effects are more
permanent, lasting beyond one season
(with animals or habitat potentially
reverting to a ‘‘normal’’ condition).
Moderate-term is defined as between 1–
3 months. These metrics and their
potential combinations help to derive
the ratings summarized in Table 8.
Temporal extent is not indicated in
Tables 10–14 below, as it did not affect
the magnitude rating for any applicant’s
specified activity.
With regard to the duration of each
estimated instance of exposure, we are
unable to produce estimates specific to
the specified activities due to the
temporal and spatial uncertainty of
vessel and cetacean movements within
the geographic region. However, given
the constant movement of vessels and
animals, all exposures are expected to
be less than a single day in duration. For
example, based on modeling of similar
activities in the Gulf of Mexico, we
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assume that most instances of exposure
would only last for a few minutes (see
Table 26–27 of Zeddies et al., 2015;
available online at
www.fisheries.noaa.gov/action/
incidental-take-authorization-oil-andgas-industry-geophysical-surveyactivity-gulf-mexico), especially in the
case of animals migrating through the
immediate vicinity of the source vessel
(e.g., Costa et al., 2016).
TABLE 8—MAGNITUDE RATING
Magnitude
rating
Amount of take
Spatial extent
Duration and frequency
High ..........................................
Any except de minimis .............
Moderate ..................................
Moderate ..................................
Moderate ..................................
Low ...........................................
Low ...........................................
Low ...........................................
De minimis ...............................
Any .................
High ................
Moderate ........
Moderate ........
Low ................
Moderate ........
Low ................
Low ................
Any .................
Any ...................................................................................................................
Any ...................................................................................................................
Any except short-term/isolated ........................................................................
Short-term/isolated ...........................................................................................
Any ...................................................................................................................
Any ...................................................................................................................
Any except short-term/intermittent or isolated .................................................
Short-term/intermittent or isolated ...................................................................
Any ...................................................................................................................
High.
Medium.
Low.
De minimis.
Adapted from Table 3.4 of Wood et al. (2012).
Consequences—Considerations of
amount, extent, and duration give an
understanding of expected magnitude of
effect for the stock or species and their
habitat, which is next considered in
context of the likely consequences of
those effects for individuals. We
consider likely relative consequences
through a qualitative evaluation of
species-specific information that helps
predict the consequences of the
information addressed through the
magnitude rating, i.e., expected effects.
The likely consequences of a given
effect to individuals is independent of
the magnitude of effect, i.e., although we
recognize that the ultimate impact is to
some degree scaled to the magnitude of
effect, the extent to which a species is
inherently vulnerable to harm from the
effects (and therefore sensitive to
magnitude) is captured by the
‘‘consequences’’ factor. This evaluation
considers factors including acoustic
sensitivity, communication range,
known aspects of behavior relevant to a
consideration of consequences of
effects, and assumed compensatory
abilities to engage in important
behaviors (e.g., breeding, foraging) in
alternate areas. The magnitude rating
and likely consequences are combined
to produce an ‘‘impact rating’’ (Table 9).
For example, if a delphinid species is
predicted to have a high amount of
disturbance and over a high degree of
spatial extent, that stock would receive
a high magnitude rating for that
particular survey. However, we may
then assess that the species may have a
high degree of compensatory ability
among individuals; therefore, our
conclusion would be that the
consequences of any effects on
individuals are likely low. The overall
impact rating in this scenario would be
moderate. Table 9 summarizes impact
rating scenarios.
TABLE 9—IMPACT RATING
Magnitude rating
Consequences
(for individuals)
Impact rating
(for species or stock)
High ....................................................................
High ....................................................................
Medium ...............................................................
Low .....................................................................
Medium ...............................................................
Low .....................................................................
De minimis ..........................................................
De minimis ..........................................................
High/medium ....................................................
Low ...................................................................
High/medium ....................................................
High ..................................................................
Low ...................................................................
Medium/low ......................................................
Medium ............................................................
Low ...................................................................
High.
Moderate.
Low.
De minimis.
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Adapted from Table 3.5 of Wood et al. (2012).
Likely consequences, as presented in
Tables 10–14 below, are considered
medium for each species of mysticete
whales (low-frequency hearing
specialists), due to the greater potential
for masking impacts at longer ranges
than other taxa and at frequencies that
overlap a larger portion of both their
hearing and vocalization ranges. Likely
consequences are considered medium
for sperm whales due to potential for
survey noise to disrupt foraging activity
(e.g., Miller et al., 2009; Farmer et al.,
2018). The likely consequences are
considered high for beaked whales due
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to the combination of known acoustic
sensitivity and expected residency
patterns, as we expect that
compensatory ability for beaked whales
will be low due to presumed residency
in certain shelf break and deepwater
canyon areas covered by the planned
survey areas. Similarly, Kogia spp. are
presumed to be more acoustically
sensitive species, but unlike beaked
whales we expect that Kogia spp. would
have a reasonable compensatory ability
to perform important behavior in
alternate areas, as they are expected to
occur broadly over the continental slope
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(e.g., Bloodworth and Odell, 2008)—
therefore, we assume that consequences
would be low for Kogia spp. generally.
Consequences are also considered low
for harbor porpoise; although they are
considered to be an acoustically
sensitive species and potentially
vulnerable to limited instances of
auditory injury (as are Kogia spp.), we
have no information to suggest that
porpoises are resident within the
specific geographic region or that the
expected disturbance events would
significantly impede their ability to
engage in critical behaviors.
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Consequences are considered low for
most delphinids, as it is unlikely that
disturbance due to survey noise would
entail significant disruption of normal
behavioral patterns, long-term
displacement, or significant potential
for masking of acoustic space. However,
for pilot whales we believe likely
consequences to be medium due to
expected residency in areas of
importance and, therefore, lack of
compensatory ability. Because the
nature of the stressor is the same across
applicants, we do not expect meaningful
differences with regard to likely
consequences.
Context
In addition to our initial impact
ratings, we then also consider additional
relevant contextual factors in a
qualitative fashion. This important
consideration of context is applied to a
given impact rating in order to produce
a final assessment of impact to the stock
or species, i.e., our negligible impact
determinations. Relevant contextual
factors include population status, other
stressors (including impacts on prey and
other habitat), and required mitigation.
Here, we reiterate discussion relating
to our development of targeted
mitigation measures and note certain
contextual factors, which are applicable
to negligible impact analyses for all five
applicants. Applicant-specific analyses
are provided later.
• We developed mitigation
requirements (i.e., time-area restrictions)
designed specifically to provide benefit
to certain species or stocks for which we
predict a relatively moderate to high
amount of exposure to survey noise
and/or which have contextual factors
that we believe necessitate special
consideration. Time-area restrictions,
described in detail in ‘‘Mitigation’’ and
depicted in Figures 3–4, are designed
specifically to provide benefit to the
North Atlantic right whale, bottlenose
dolphin, sperm whale, beaked whales,
and pilot whales. In addition, we expect
these areas to provide some subsidiary
benefit to additional species that may be
present. In particular, Area #4 (Figure
4), although delineated in order to
specifically provide an area of
anticipated benefit to beaked whales,
sperm whales, and pilot whales, is
expected to host a diverse assemblage of
cetacean species. The output of the
Roberts et al. (2016) models, as used in
core abundance area analyses (described
in detail in ‘‘Mitigation’’), indicates that
species most likely to derive subsidiary
benefit from this time-area restriction
include the bottlenose dolphin (offshore
stock), Risso’s dolphin, and common
dolphin. For species with density
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predicted through stratified models,
core abundance analysis is not possible
and assumptions regarding potential
benefit of time-area restrictions are
based on known ecology of the species
and sightings patterns and are less
robust. Nevertheless, subsidiary benefit
for Areas #1–4 (Figure 4) should be
expected for species known to be
present in these areas (e.g., assumed
affinity for shelf/slope/abyss areas off
Cape Hatteras): Kogia spp., pantropical
spotted dolphin, Clymene dolphin, and
rough-toothed dolphin.
These mitigation measures benefit
both the primary species for which they
were designed and the species that may
benefit secondarily by reducing impacts
to marine mammal habitat and by
reducing the numbers of individuals
likely to be exposed to survey noise. For
resident species in areas where seasonal
closures are required, we also expect
reduction in the numbers of times that
individuals are exposed to survey noise
(also discussed in ‘‘Small Numbers
Analyses,’’ below). Perhaps of greater
importance, we expect that these
restrictions will reduce disturbance of
these species in the places most
important to them for critical behaviors
such as foraging and socialization. Area
#1 (Figure 4), which is a year-round
closure, is assumed to be an area
important for beaked whale foraging,
while Areas #2–3 (also year-round
closures) are assumed to provide
important foraging opportunities for
sperm whales as well as beaked whales.
Area #4, a seasonal closure, is
comprised of shelf-edge habitat where
beaked whales and pilot whales are
believed to be year-round residents as
well as slope and abyss habitat
predicted to contain high abundance of
sperm whales during the period of
closure. Further detail regarding
rationale for these closures is provided
under ‘‘Mitigation.’’
• The North Atlantic right whale, sei
whale, fin whale, blue whale, and sperm
whale are listed as endangered under
the Endangered Species Act, and all
coastal stocks of bottlenose dolphin are
designated as depleted under the
MMPA (and have recently experienced
an Unusual Mortality Event, described
earlier in this document). However, sei
whales and blue whales are unlikely to
be meaningfully impacted by the
specified activities (see ‘‘Rare Species’’
below). All four mysticete species are
also classified as endangered (i.e.,
‘‘considered to be facing a very high risk
of extinction in the wild’’) on the
International Union for Conservation of
Nature Red List of Threatened Species,
whereas the sperm whale is classified as
vulnerable (i.e., ‘‘considered to be facing
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a high risk of extinction in the wild’’)
(IUCN, 2017). Our required mitigation is
designed to avoid impacts to the right
whale and to depleted stocks of
bottlenose dolphin. Survey activities
must avoid all areas where the right
whale and coastal stocks of bottlenose
dolphin are reasonably expected to
occur (or, for the right whale,
comparable protection would be
achieved through implementation of a
NMFS-approved mitigation and
monitoring plan at distances between
47–80 km offshore; see ‘‘Mitigation’’),
and we require shutdown of the
acoustic source upon observation of any
right whale at extended distance
compared with the standard shutdown
requirement. If the observed right whale
is within the behavioral harassment
zone, it would still be considered taken,
but by immediately shutting down the
acoustic source the duration of
harassment is minimized and the
significance of the harassment event
reduced as much as possible.
Although listed as endangered, the
primary threat faced by the sperm whale
(i.e., commercial whaling) has been
eliminated and, further, sperm whales
in the western North Atlantic were little
affected by modern whaling (Taylor et
al., 2008). Current potential threats to
the species globally include vessel
strikes, entanglement in fishing gear,
anthropogenic noise, exposure to
contaminants, climate change, and
marine debris. However, for the North
Atlantic stock, the most recent estimate
of annual human-caused mortality and
serious injury (M/SI) is 22 percent of the
potential biological removal (PBR) level
for the stock. As described previously,
PBR is defined as ‘‘the maximum
number of animals, not including
natural mortalities, that may be removed
from a marine mammal stock while
allowing that stock to reach or maintain
its optimum sustainable population.’’
For depleted stocks, levels of humancaused mortality and serious injury
exceeding the PBR level are likely to
delay restoration of the stock to OSP
level by more than ten percent in
comparison with recovery time in the
absence of human-caused M/SI.
The most recent status review for the
species stated that existing regulatory
mechanisms appear to minimize threats
to sperm whales and that, despite
uncertainty regarding threats such as
climate change, contaminants, and
anthropogenic noise, the significance of
threat facing the species should be
considered low to moderate (NMFS,
2015b). Nevertheless, existing empirical
data (e.g., Miller et al., 2009; Farmer et
al., 2018) highlight the potential for
seismic survey activity to negatively
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impact foraging behavior of sperm
whales. In consideration of this
likelihood, the species status, and the
relatively high amount of predicted
exposures to survey noise, we have
given special consideration to
mitigation focused on sperm whales and
have defined time-area restrictions (see
‘‘Mitigation’’ and Figure 4) specifically
designed to reduce such impacts on
sperm whales in areas expected to be of
greatest importance (i.e., slope habitat
and deepwater canyons).
Although the primary direct threat to
fin whales was addressed through the
moratorium on commercial whaling,
vessel strike and entanglement in
commercial fishing gear remain as
substantial direct threats for the species
in the western North Atlantic. As noted
below, the most recent estimate of
annual average human-caused mortality
for the fin whale in U.S. waters is equal
to the PBR value (Table 2). In addition,
mysticete whales are particularly
sensitive to sound in the frequency
range output from use of airgun arrays
(e.g., NMFS, 2018). However, there is
conflicting evidence regarding the
degree to which this sound source may
significantly disrupt the behavior of
mysticete whales. Generally speaking,
mysticete whales have been observed to
react to seismic vessels but have also
been observed continuing normal
behavior in the presence of seismic
vessels, and behavioral context at the
time of acoustic exposure may be
influential in the degree to which
whales display significant behavioral
reactions. In addition, while Edwards et
al. (2015) found that fin whales were
likely present in all seasons in U.S.
waters north of 35° N, most important
habitat areas are not expected to occur
in the planned survey areas. Primary
feeding areas are outside the project area
in the Gulf of Maine and off Long Island
(LaBrecque et al., 2015) and, while Hain
et al. (1992) suggested that calving
occurs during winter in the midAtlantic, Hayes et al. (2017) state that it
is unknown where calving, mating, and
wintering occur for most of the
population. Further, fin whales are not
considered to engage in regular mass
movements along well-defined
migratory corridors (NMFS, 2010b). The
models described by Roberts et al.
(2016), which predicted density at a
monthly time step, suggest an
expectation that, while fin whales may
be present year-round in shelf and slope
waters north of Cape Hatteras, the large
majority of predicted abundance in U.S.
waters would be found outside the
planned survey areas to the north. Very
few fin whales are likely present in the
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planned survey areas in summer
months. Therefore, we have determined
that development of time-area
restriction specific to fin whales is not
warranted. However, fin whales present
along the shelf break north of Cape
Hatteras during the closure period
associated with Area #4 (Figure 4)
would be expected to benefit from the
time-area restriction designed primarily
to benefit pilot whales, beaked whales,
and sperm whales.
• Critical habitat is designated only
for the North Atlantic right whale, and
there are no biologically important areas
(BIA) described within the region (other
than for the right whale, and the
described BIA is similar to designated
critical habitat). Our required mitigation
is designed to avoid impacts to
important habitat for the North Atlantic
right whale (or achieve comparable
protection through implementation of a
NMFS-approved mitigation and
monitoring plan at distances between
47–80 km offshore; see ‘‘Mitigation’’).
• High levels of average annual
human-caused M/SI (approaching or
exceeding the PBR level) are ongoing for
the North Atlantic right whale, sei
whale, fin whale, and for both longfinned and short-finned pilot whales
(see Table 2). Average annual M/SI is
considered unknown for the blue whale
and the false killer whale (PBR is
undetermined for a number of other
species (Table 2), but average annual
human-caused M/SI is zero for all of
these). Separately, there are ongoing
UMEs for humpback whales and minke
whales (as well as for the right whale),
as discussed previously in this notice.
Although threats are considered poorly
known for North Atlantic blue whales,
PBR is less than one and ship strike is
a known cause of mortality for all
mysticete whales. The most recent
record of ship strike mortality for a blue
whale in the U.S. EEZ is from 1998
(Waring et al., 2010). False killer whales
also have a low PBR value (2.1), and
may be susceptible to mortality in
commercial fisheries. One false killer
whale was reported as entangled in the
pelagic longline fishery in 2011, but was
released alive and not seriously injured.
Separately, a stranded false killer whale
in 2009 was classified as due to a
fishery interaction. Incidental take of
the sei whale, blue whale, false killer
whale, and long-finned pilot whale is
considered unlikely and we authorize
take by behavioral harassment only for
a single group of each of the first three
species as a precaution. Although longfinned pilot whales are unlikely to
occur in the action area in significant
numbers, the density models that
inform our exposure estimates consider
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63367
pilot whales as a guild. It is important
to note that our discussion of M/SI in
relation to PBR values provides
necessary contextual information
related to the status of stocks; we do not
equate harassment with M/SI.
We addressed our consideration of
specific mitigation efforts for the right
whale and fin whale above. For minke
whales, although the ongoing UME is
under investigation (as occurs for all
UMEs), this event does not provide
cause for concern regarding populationlevel impacts, as the likely population
abundance is greater than 20,000
whales. Even though the PBR value is
based on an abundance for U.S. waters
that is negatively biased and a small
fraction of the true population
abundance, annual M/SI does not
exceed the calculated PBR value for
minke whales.
With regard to humpback whales, the
UME does not yet provide cause for
concern regarding population-level
impacts. Despite the UME, the relevant
population of humpback whales (the
West Indies breeding population, or
distinct population segment (DPS))
remains healthy. Prior to 2016,
humpback whales were listed under the
ESA as an endangered species
worldwide. Following a 2015 global
status review (Bettridge et al., 2015),
NMFS established 14 DPSs with
different listing statuses (81 FR 62259;
September 8, 2016) pursuant to the ESA.
The West Indies DPS, which consists of
the whales whose breeding range
includes the Atlantic margin of the
Antilles from Cuba to northern
Venezuela, and whose feeding range
primarily includes the Gulf of Maine,
eastern Canada, and western Greenland,
was delisted. The status review
identified harmful algal blooms, vessel
collisions, and fishing gear
entanglements as relevant threats for
this DPS, but noted that all other threats
are considered likely to have no or
minor impact on population size or the
growth rate of this DPS (Bettridge et al.,
2015). As described in Bettridge et al.
(2015), the West Indies DPS has a
substantial population size (i.e.,
approximately 10,000; Stevick et al.,
2003; Smith et al., 1999; Bettridge et al.,
2015), and appears to be experiencing
consistent growth.
In response to this population context
concern for pilot whales, in conjunction
with relatively medium to high amount
of predicted exposures to survey noise
for pilot whales, we have given special
consideration to mitigation focused on
pilot whales and have defined time-area
restrictions (see ‘‘Mitigation’’ and Figure
4) specifically designed to reduce such
impacts on pilot whales in areas
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expected to be of greatest importance
(i.e., shelf edge north of Cape Hatteras).
• Beaked whales are considered to be
particularly acoustically sensitive (e.g.,
Tyack et al., 2011; DeRuiter et al., 2013;
Stimpert et al., 2014; Miller et al., 2015).
Considering this sensitivity in
conjunction with the relatively high
amount of predicted exposures to
survey noise, we have given special
consideration to mitigation focused on
beaked whales and have defined timearea restrictions (see ‘‘Mitigation’’ and
Figure 4) specifically designed to reduce
such impacts on beaked whales in areas
expected to be of greatest importance
(i.e., shelf edge south of Cape Hatteras
and deepwater canyon areas).
• Given the current declining
population status of North Atlantic right
whales, it is important to understand
the likely demographics of the expected
taking. Therefore, we obtained data from
the North Atlantic Right Whale
Consortium Database (pers. comm., T.A.
Gowan to E. Patterson, November 8,
2017), consisting of standardized
sighting records of right whales from
2005 to 2013 from South Carolina to
Florida. Because of the low total number
of expected exposure for right whales,
we could not reasonably apply this
information on an applicant-specific
basis and therefore present these
findings for the total expected taking
across all applicants. Based on this
information, of the total 23 takes of
North Atlantic right whales (now
revised downward to 19 takes on the
basis of Spectrum’s modified survey
plan; see ‘‘Spectrum Survey Plan
Modification’’), it should be expected
that four exposures could be of adult
females with calves, two of adult
females without calves, five of adult
males, 11 of juveniles of either sex,
three of calves of either sex, one of an
adult of unknown sex, and two of
animals of unknown age and sex. It is
important to note that age class
estimates sum to greater than the
originally expected total of 23 due to
conservative rounding up in presenting
the maximum number of each age-sex
class that might be exposed; this should
not be construed as an assumption that
there would be more total takes of right
whales than are authorized across all
applicants. Each of these exposures
represents a single instance of Level B
harassment and is therefore not
considered as a meaningful impact to
individuals that could lead to
population-level impacts.
Rare Species
As described previously, there are
multiple species that should be
considered rare in the survey areas and
for which we authorize only nominal
and precautionary take of a single group
for each applicant survey. Specific to
each of the five applicant companies,
we do not expect meaningful impacts to
these species (i.e., sei whale, Bryde’s
whale, blue whale, killer whale, false
killer whale, pygmy killer whale,
melon-headed whale, northern
bottlenose whale, spinner dolphin,
Fraser’s dolphin, Atlantic white-sided
dolphin) and find that the take from
each of the specified activities will have
a negligible impact on these marine
mammal species. We do not discuss
these 11 species further in these
analyses.
Spectrum
Spectrum originally planned a 165day survey program, or 45 percent of the
year (approximately two seasons). The
original survey plan would cover a large
spatial extent (i.e., a majority of the midand south Atlantic; see Figure 1 of
Spectrum’s application). Therefore,
although that survey would be longterm (i.e., greater than one season) in
total duration, we would not expect the
duration of effect to be greater than
moderate and intermittent in any given
area. Table 10 displays relevant
information leading to impact ratings for
each species resulting from Spectrum’s
original survey plan. In general, we note
that although the temporal and spatial
scale of the planned survey activity is
large, it is not occupying the spatial
extent all at one time. The fact that this
mobile acoustic source would be
moving across large areas (as compared
with geophysical surveys with different
objectives that may require focused
effort over long periods of time in
smaller areas) means that more
individuals may receive limited
exposure to survey noise, versus fewer
individuals receiving more intense
exposure and/or for longer periods of
time. The nature of such potentially
transitory exposure (which we
nevertheless assume here is of moderate
duration and intermittent, versus
isolated) means that the potential
significance of behavioral disruption
and potential for longer-term avoidance
of important areas is limited. Please see
‘‘Spectrum Survey Plan Modification,’’
below, for additional information
describing the modified survey plan,
findings made in context of the analysis
presented below, and authorized take
for Spectrum (Table 17).
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TABLE 10—MAGNITUDE AND IMPACT RATINGS, SPECTRUM
Species
Amount
Spatial extent
Magnitude
rating
Consequences
North Atlantic right whale .....................................
Humpback whale ..................................................
Minke whale ..........................................................
Fin whale ..............................................................
Sperm whale .........................................................
Kogia spp ..............................................................
Beaked whales .....................................................
Rough-toothed dolphin .........................................
Bottlenose dolphin ................................................
Clymene dolphin ...................................................
Atlantic spotted dolphin ........................................
Pantropical spotted dolphin ..................................
Striped dolphin ......................................................
Common dolphin ...................................................
Risso’s dolphin ......................................................
Pilot whales ...........................................................
Harbor porpoise ....................................................
De minimis ........
De minimis ........
De minimis ........
Low ...................
Low ...................
Low ...................
Low ...................
Moderate ...........
High ...................
High ...................
Moderate ...........
Moderate ...........
Low ...................
Low ...................
De minimis ........
Low ...................
De minimis ........
Low-Moderate ..
Low-Moderate ..
Low-High ..........
Low ..................
Moderate ..........
High .................
Moderate ..........
High .................
High .................
High .................
Moderate ..........
High .................
Low ..................
Low-moderate ..
Low-moderate ..
Moderate ..........
Low ..................
De minimis .......
De minimis .......
De minimis .......
Medium ............
Medium ............
High .................
Medium ............
High .................
High .................
High .................
High .................
High .................
Medium ............
Medium ............
De minimis .......
Medium ............
De minimis .......
Medium ..............
Medium ..............
Medium ..............
Medium ..............
Medium ..............
Low .....................
High ....................
Low .....................
Low .....................
Low .....................
Low .....................
Low .....................
Low .....................
Low .....................
Low .....................
Medium ..............
Low .....................
Impact rating 1
Low.
Low.
Low.
Moderate.
Moderate.
Moderate.
Moderate.
Moderate.
Moderate.
Moderate.
Moderate.
Moderate.
Low.
Low.
De minimus.
Moderate.
De minimis.
1 Impact rating does not indicate whether overall impact to the species or stock is negligible, but is considered with relevant contextual factors
(described generally above and specifically below) in order to ultimately determine whether the effects of the specified activity on the affected
species or stock are negligible.
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Fmt 4701
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E:\FR\FM\07DEN2.SGM
07DEN2
amozie on DSK3GDR082PROD with NOTICES2
Federal Register / Vol. 83, No. 235 / Friday, December 7, 2018 / Notices
The North Atlantic right whale is
endangered, has a very low population
size, and faces significant additional
stressors. Therefore, regardless of even a
low impact rating, we believe that the
required mitigation described
previously is critically important in
order for us to make the necessary
finding and it is with consideration of
this mitigation that we find the take
from Spectrum’s survey activities will
have a negligible impact on the North
Atlantic right whale. The fin whale
receives a moderate impact rating
overall, but we expect that for two
seasons (summer and fall) almost no fin
whales will be present in the survey
area. For the remainder of the year, it is
likely that less than one quarter of the
population will be present within the
survey area (Roberts et al., 2016),
meaning that despite medium rankings
for magnitude and likely consequences,
these impacts would be experienced by
only a small subset of the overall
population. In consideration of the
moderate impact rating, the likely
proportion of the population that may
be affected by the specified activities,
and the lack of evidence that the survey
area is host to important behaviors that
may be disrupted, we find the take from
Spectrum’s survey activities will have a
negligible impact on the fin whale.
Magnitude ratings for the sperm
whale and beaked whales are medium;
however, consequence factors are
medium and high, respectively.
Magnitude rating for pilot whales is
medium, but similar to beaked whales,
we expect that compensatory ability
will be low (high consequence rating)
due to presumed residency in areas
targeted by the planned survey. These
factors lead to moderate impact ratings
for all three species/species groups.
However, regardless of impact rating,
the consideration of likely consequences
and contextual factors for all three taxa
leads us to conclude that targeted
mitigation is important to support a
finding that the effects of the survey will
have a negligible impact on these
species. As described previously, sperm
whales are an endangered species with
particular susceptibility to disruption of
foraging behavior, beaked whales are
particularly acoustically sensitive (with
presumed low compensatory ability),
and pilot whales are sensitive to
additional stressors due to a high degree
of mortality in commercial fisheries
(and also with low compensatory
ability). Finally, due to their acoustic
sensitivity, we require shutdown of the
acoustic source upon detection of a
beaked whale at extended distance from
the source vessel. In consideration of
VerDate Sep<11>2014
18:20 Dec 06, 2018
Jkt 247001
the required mitigation, we find the take
from Spectrum’s survey activities will
have a negligible impact on the sperm
whale, beaked whales (i.e., Ziphius
cavirostris and Mesoplodon spp.), and
pilot whales (i.e., Globicephala spp.).
Kogia spp. receive a moderate impact
rating. However, although NMFS does
not currently identify a trend for these
populations, recent survey effort and
stranding data show a simultaneous
increase in at-sea abundance and
strandings, suggesting growing Kogia
spp. abundance (NMFS, 2011; 2013a;
Waring et al., 2007; 2013). Finally, we
expect that Kogia spp. will receive
subsidiary benefit from the required
mitigation targeted for sperm whales,
beaked whales, and pilot whales and,
although minimally effective due to the
difficulty of at-sea observation of Kogia
spp., we require shutdown of the
acoustic source upon observation of
Kogia spp. at extended distance from the
source vessel. In consideration of these
factors—likely population increase and
required mitigation—we find the take
from Spectrum’s survey activities will
have a negligible impact on Kogia spp.
As described in the introduction to
this analysis, it is assumed that likely
consequences are somewhat higher for
species of mysticete whales (lowfrequency hearing specialists) due to the
greater potential for masking impacts at
longer ranges than other taxa and at
frequencies that overlap a larger portion
of both their hearing and vocalization
ranges. Therefore, despite de minimis
magnitude ratings, we expect some
consequences to individual humpback
and minke whales, i.e., leading to a low
impact rating. However, given the
minimal amount of interaction expected
between these species and the survey
activities, and in consideration of the
overall low impact ratings, we find the
take from Spectrum’s planned survey
activities will have a negligible impact
on the humpback whale and minke
whale.
Despite medium to high magnitude
ratings, remaining delphinid species
receive low to moderate impact ratings
due to low consequences rating relating
to a lack of propensity for behavioral
disruption due to airgun survey activity
and our expectation that these species
would generally have relatively high
compensatory ability. In addition,
contextually these species do not have
significant issues relating to population
status or context. Many oceanic
delphinid species are generally more
associated with dynamic oceanographic
characteristics rather than static
physical features, and those species
(such as common dolphin) with
substantial distribution to the north of
PO 00000
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Fmt 4701
Sfmt 4703
63369
the survey area would likely be little
affected at the population level by the
activity. For example, both species of
spotted dolphin and the offshore stock
of bottlenose dolphin range widely over
slope and abyssal waters (e.g., Waring et
al., 2014; Hayes et al., 2017; Roberts et
al., 2016), while the rough-toothed
dolphin does not appear bound by water
depth in its range (Ritter, 2002; Wells et
al., 2008). Our required mitigation
largely eliminates potential effects to
depleted coastal stocks of bottlenose
dolphin. We also expect that meaningful
subsidiary benefit will accrue to certain
species from the mitigation targeted for
sperm whales, beaked whales, and pilot
whales, most notably to species
presumed to have greater association
with shelf break waters north of Cape
Hatteras (e.g., offshore bottlenose
dolphins, common dolphins, and
Risso’s dolphins). In consideration of
these factors—overall impact ratings
and context including required
mitigation—we find the take from
Spectrum’s planned survey activities
will have a negligible impact on
remaining delphinid species (i.e., all
stocks of bottlenose dolphin, two
species of spotted dolphin, roughtoothed dolphin, striped dolphin,
common dolphin, and Clymene
dolphin).
For those species with de minimis
impact ratings we believe that, absent
additional relevant concerns related to
population status or context, the rating
implies that a negligible impact should
be expected as a result of the specified
activity. No such concerns exist for
these species, and we find the take from
Spectrum’s survey activities will have a
negligible impact on the Risso’s dolphin
and harbor porpoise.
In summary, based on the analysis
contained herein of the likely effects of
the specified activity on marine
mammals and their habitat, and taking
into consideration the implementation
of the required monitoring and
mitigation measures, we find that the
total marine mammal take from
Spectrum’s survey activities will have a
negligible impact on all affected marine
mammal species or stocks.
TGS—TGS has planned a 308-day
survey program, or 84 percent of the
year (slightly more than three seasons).
However, the planned survey would
cover a large spatial extent (i.e., a
majority of the mid- and south Atlantic;
see Figures 1–1 to 1–4 of TGS’s
application). Therefore, although the
survey would be long-term (i.e., greater
than one season) in total duration, we
would not expect the duration of effect
to be greater than moderate and
intermittent in any given area. We note
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07DEN2
63370
Federal Register / Vol. 83, No. 235 / Friday, December 7, 2018 / Notices
that TGS plans to deploy two
independent source vessels, which
would in effect increase the spatial
extent of survey noise at any one time
but, because the vessels would not be
operating within the same area or
reshooting lines already covered, this
would not be expected to increase the
duration or frequency of exposure
experienced by individual animals.
Table 11 displays relevant information
leading to impact ratings for each
species resulting from TGS’s survey. In
general, we note that although the
temporal and spatial scale of the
planned survey activity is large, the fact
that these mobile acoustic sources
would be moving across large areas (as
compared with geophysical surveys
with different objectives that may
require focused effort over long periods
of time in smaller areas) means that
more individuals may receive limited
exposure to survey noise, versus fewer
individuals receiving more intense
exposure and/or for longer periods of
time. The nature of such potentially
transitory exposure (which we
nevertheless assume here is of moderate
duration and intermittent, versus
isolated) means that the potential
significance of behavioral disruption
and potential for longer-term avoidance
of important areas is limited.
TABLE 11—MAGNITUDE AND IMPACT RATINGS, TGS
Species
Amount
Spatial extent
Magnitude
rating
Consequences
North Atlantic right whale .....................................
Humpback whale ..................................................
Minke whale ..........................................................
Fin whale ..............................................................
Sperm whale .........................................................
Kogia spp ..............................................................
Beaked whales .....................................................
Rough-toothed dolphin .........................................
Bottlenose dolphin ................................................
Clymene dolphin ...................................................
Atlantic spotted dolphin ........................................
Pantropical spotted dolphin ..................................
Striped dolphin ......................................................
Common dolphin ...................................................
Risso’s dolphin ......................................................
Pilot whales ...........................................................
Harbor porpoise ....................................................
De minimis ........
De minimis ........
De minimis ........
Moderate ...........
High ...................
High ...................
High ...................
High ...................
High ...................
De minimis ........
High ...................
Moderate ...........
Low ...................
High ...................
Moderate ...........
High ...................
De minimis ........
Low-Moderate ..
Low-Moderate ..
Low-High ..........
Low ..................
Moderate ..........
High .................
Moderate ..........
High .................
High .................
High .................
Moderate ..........
High .................
Low ..................
Low-moderate ..
Low-moderate ..
Moderate ..........
Low ..................
De minimis .......
De minimis .......
De minimis .......
Medium ............
High .................
High .................
High .................
High .................
High .................
De minimis .......
High .................
High .................
Medium ............
High .................
High .................
High .................
De minimis .......
Medium ..............
Medium ..............
Medium ..............
Medium ..............
Medium ..............
Low .....................
High ....................
Low .....................
Low .....................
Low .....................
Low .....................
Low .....................
Low .....................
Low .....................
Low .....................
Medium ..............
Low .....................
Impact rating 1
Low.
Low.
Low.
Moderate.
High.
Moderate.
High.
Moderate.
Moderate.
De minimis.
Moderate.
Moderate.
Low.
Moderate.
Moderate.
High.
De minimis.
amozie on DSK3GDR082PROD with NOTICES2
1 Impact rating does not indicate whether overall impact to the species or stock is negligible, but is considered with relevant contextual factors
(described generally above and specifically below) in order to ultimately determine whether the effects of the specified activity on the affected
species or stock are negligible.
The North Atlantic right whale is
endangered, has a very low population
size, and faces significant additional
stressors. Therefore, regardless of even a
low impact rating, we believe that the
required mitigation described
previously is critically important in
order for us to make the necessary
finding and it is with consideration of
this mitigation that we find the take
from TGS’s survey activities will have a
negligible impact on the North Atlantic
right whale. The fin whale receives a
moderate impact rating overall, but we
expect that for two seasons (summer
and fall) almost no fin whales will be
present in the survey area. For the
remainder of the year, it is likely that
less than one quarter of the population
will be present within the survey area
(Roberts et al., 2016), meaning that
despite medium rankings for magnitude
and likely consequences, these impacts
would be experienced by only a small
subset of the overall population. In
consideration of the moderate impact
rating, the likely proportion of the
population that may be affected by the
specified activities, and the lack of
evidence that the survey area is host to
important behaviors that may be
VerDate Sep<11>2014
18:20 Dec 06, 2018
Jkt 247001
disrupted, we find the take from TGS’s
survey activities will have a negligible
impact on the fin whale.
Magnitude ratings for the sperm
whale, beaked whales, and pilot whales
are high and, further, consequence
factors reinforce high impact ratings for
all three. In addition, the consideration
of likely consequences and contextual
factors leads us to conclude that
targeted mitigation is important to
support a finding that the effects of the
survey will have a negligible impact on
these species. As described previously,
sperm whales are an endangered species
with particular susceptibility to
disruption of foraging behavior, beaked
whales are particularly acoustically
sensitive (with presumed low
compensatory ability and, therefore,
high consequence rating), and pilot
whales are sensitive to additional
stressors due to a high degree of
mortality in commercial fisheries (and
also with low compensatory ability).
Finally, due to their acoustic sensitivity,
we have required shutdown of the
acoustic source upon observation of a
beaked whale at extended distance from
the source vessel. In consideration of
the required mitigation, we find the take
PO 00000
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Fmt 4701
Sfmt 4703
from TGS’s survey activities will have a
negligible impact on the sperm whale,
beaked whales (i.e., Ziphius cavirostris
and Mesoplodon spp.), and pilot whales
(i.e., Globicephala spp.).
Kogia spp. receive a moderate impact
rating. However, although NMFS does
not currently identify a trend for these
populations, recent survey effort and
stranding data show a simultaneous
increase in at-sea abundance and
strandings, suggesting growing Kogia
spp. abundance (NMFS, 2011; 2013a;
Waring et al., 2007; 2013). Finally, we
expect that Kogia spp. will receive
subsidiary benefit from the mitigation
targeted for sperm whales, beaked
whales, and pilot whales and, although
minimally effective due to the difficulty
of at-sea observation of Kogia spp., we
have required shutdown of the acoustic
source upon observation of Kogia spp. at
extended distance from the source
vessel. In consideration of these
factors—likely population increase and
required mitigation—we find the take
from TGS’s survey activities will have a
negligible impact on Kogia spp.
As described in the introduction to
this analysis, it is assumed that likely
consequences are somewhat higher for
E:\FR\FM\07DEN2.SGM
07DEN2
Federal Register / Vol. 83, No. 235 / Friday, December 7, 2018 / Notices
species of mysticete whales (lowfrequency hearing specialists) due to the
greater potential for masking impacts at
longer ranges than other taxa and at
frequencies that overlap a larger portion
of both their hearing and vocalization
ranges. Therefore, despite de minimis
magnitude ratings, we expect some
consequences to individual humpback
and minke whales, i.e., leading to a low
impact rating. However, given the
minimal amount of interaction expected
between these species and the survey
activities, and in consideration of the
overall low impact ratings, we find the
take from TGS’s planned survey
activities will have a negligible impact
on the humpback whale and minke
whale.
Despite high magnitude ratings, most
remaining delphinid species receive
moderate impact ratings (with the
exception of the striped dolphin, with
medium magnitude rating and low
impact rating), due to low consequences
rating relating to a lack of propensity for
behavioral disruption due to airgun
survey activity and our expectation that
these species would generally have
relatively high compensatory ability. In
addition, contextually these species do
not have significant issues relating to
population status or context. Many
oceanic delphinid species are generally
more associated with dynamic
oceanographic characteristics rather
than static physical features, and those
species (such as common dolphin) with
substantial distribution to the north of
the survey area would likely be little
affected at the population level by the
specified activity. For example, both
species of spotted dolphin and the
offshore stock of bottlenose dolphin
range widely over slope and abyssal
waters (e.g., Waring et al., 2014; Hayes
et al., 2017; Roberts et al., 2016), while
the rough-toothed dolphin does not
appear bound by water depth in its
range (Ritter, 2002; Wells et al., 2008).
Our required mitigation largely
eliminates potential effects to depleted
coastal stocks of bottlenose dolphin. We
also expect that meaningful subsidiary
benefit will accrue to certain species
from the mitigation targeted for sperm
whales, beaked whales, and pilot
whales, most notably to species
presumed to have greater association
with shelf break waters north of Cape
Hatteras (e.g., offshore bottlenose
dolphins, common dolphins, and
Risso’s dolphins). In consideration of
these factors—overall impact ratings
and context including required
mitigation—we find the take from TGS’s
survey activities will have a negligible
impact on most remaining delphinid
species (i.e., all stocks of bottlenose
dolphin, two species of spotted dolphin,
rough-toothed dolphin, striped dolphin,
common dolphin, and Risso’s dolphin).
For those species with de minimis
impact ratings we believe that, absent
additional relevant concerns related to
population status or context, the rating
implies that a negligible impact should
be expected as a result of the specified
activity. No such concerns exist for
these species, and we find the take from
TGS’s survey activities will have a
negligible impact on the Clymene
dolphin and harbor porpoise.
In summary, based on the analysis
contained herein of the likely effects of
63371
the specified activity on marine
mammals and their habitat, and taking
into consideration the implementation
of the required monitoring and
mitigation measures, we find that the
total marine mammal take from TGS’s
survey activities will have a negligible
impact on all affected marine mammal
species or stocks.
ION—ION has planned a 70-day
survey program, or 19 percent of the
year (slightly less than one season).
However, the planned survey would
cover a large spatial extent (i.e., a
majority of the mid- and south Atlantic;
see Figure 1 of ION’s application).
Therefore, although the survey would be
moderate-term (i.e., from 1–3 months) in
total duration, we would not expect the
duration of effect to be greater than
short and isolated to intermittent in any
given area. Table 12 displays relevant
information leading to impact ratings for
each species resulting from ION’s
survey. In general, we note that
although the temporal and spatial scale
of the planned survey activity is large,
the fact that this mobile acoustic source
would be moving across large areas (as
compared with geophysical surveys
with different objectives that may
require focused effort over long periods
of time in smaller areas) means that
more individuals may receive limited
exposure to survey noise, versus fewer
individuals receiving more intense
exposure and/or for longer periods of
time. The nature of such potentially
transitory exposure means that the
potential significance of behavioral
disruption and potential for longer-term
avoidance of important areas is limited.
TABLE 12—MAGNITUDE AND IMPACT RATINGS, ION
amozie on DSK3GDR082PROD with NOTICES2
Species
Amount
North Atlantic right whale .....................................
Humpback whale ..................................................
Minke whale ..........................................................
Fin whale ..............................................................
Sperm whale .........................................................
Kogia spp ..............................................................
Beaked whales .....................................................
Rough-toothed dolphin .........................................
Bottlenose dolphin ................................................
Clymene dolphin ...................................................
Atlantic spotted dolphin ........................................
Pantropical spotted dolphin ..................................
Striped dolphin ......................................................
Common dolphin ...................................................
Risso’s dolphin ......................................................
Pilot whales ...........................................................
Harbor porpoise ....................................................
De
De
De
De
De
De
De
De
De
De
De
De
De
De
De
De
De
minimis
minimis
minimis
minimis
minimis
minimis
minimis
minimis
minimis
minimis
minimis
minimis
minimis
minimis
minimis
minimis
minimis
Magnitude
rating
Spatial extent
........
........
........
........
........
........
........
........
........
........
........
........
........
........
........
........
........
Low-Moderate ..
Low-Moderate ..
Low-High ..........
Low ..................
Moderate ..........
High .................
Moderate ..........
High .................
High .................
High .................
Moderate ..........
High .................
Low ..................
Low-moderate ..
Low-moderate ..
Moderate ..........
Low ..................
De
De
De
De
De
De
De
De
De
De
De
De
De
De
De
De
De
minimis
minimis
minimis
minimis
minimis
minimis
minimis
minimis
minimis
minimis
minimis
minimis
minimis
minimis
minimis
minimis
minimis
Consequences
.......
.......
.......
.......
.......
.......
.......
.......
.......
.......
.......
.......
.......
.......
.......
.......
.......
Medium ..............
Medium ..............
Medium ..............
Medium ..............
Medium ..............
Low .....................
High ....................
Low .....................
Low .....................
Low .....................
Low .....................
Low .....................
Low .....................
Low .....................
Low .....................
Medium ..............
Low .....................
Impact rating 1
Low.
Low.
Low.
Low.
Low.
De minimis.
Low.
De minimis.
De minimis.
De minimis.
De minimis.
De minimis.
De minimis.
De minimis.
De minimis.
Low.
De minimis.
1 Impact rating does not indicate whether overall impact to the species or stock is negligible, but is considered with relevant contextual factors
(described generally above and specifically below) in order to ultimately determine whether the effects of the specified activity on the affected
species or stock are negligible.
VerDate Sep<11>2014
18:20 Dec 06, 2018
Jkt 247001
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E:\FR\FM\07DEN2.SGM
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Federal Register / Vol. 83, No. 235 / Friday, December 7, 2018 / Notices
The North Atlantic right whale is
endangered, has a very low population
size, and faces significant additional
stressors. Therefore, regardless of
impact rating, we believe that the
required mitigation described
previously is critically important in
order for us to make the necessary
finding and it is with consideration of
this mitigation that we find the take
from ION’s planned survey activities
will have a negligible impact on the
North Atlantic right whale.
Also regardless of impact rating,
consideration of assumed behavioral
susceptibility and lack of compensatory
ability (i.e., consequence factors) as well
as additional contextual factors leads us
to conclude that the required targeted
time-area mitigation described
previously is important to support a
finding that the effects of the planned
survey will have a negligible impact for
the sperm whale, beaked whales (i.e.,
Ziphius cavirostris and Mesoplodon
spp.), and pilot whales (i.e.,
Globicephala spp.). As described
previously, sperm whales are an
endangered species with particular
susceptibility to disruption of foraging
behavior, beaked whales are particularly
acoustically sensitive, and pilot whales
are sensitive to additional stressors due
to a high degree of mortality in
commercial fisheries. Further, we
expect that compensatory ability for
beaked whales will be low due to
presumed residency in certain shelf
break and deepwater canyon areas
covered by the survey area and that
compensatory ability for pilot whales
will also be low due to presumed
residency in areas targeted by the
planned survey (when compensatory
ability is assumed to be low, we assign
a high consequence factor). Kogia spp.
are also considered to have heightened
acoustic sensitivity and therefore we
have required shutdown of the acoustic
source upon observation of a beaked
whale or a Kogia spp. at extended
distance from the source vessel. In
consideration of the required mitigation,
we find the take from ION’s survey
activities will have a negligible impact
on the sperm whale, beaked whales,
pilot whales, and Kogia spp.
As described in the introduction to
this analysis, it is assumed that likely
consequences are somewhat higher for
species of mysticete whales (lowfrequency hearing specialists) due to the
greater potential for masking impacts at
longer ranges than other taxa and at
frequencies that overlap a larger portion
of both their hearing and vocalization
ranges. Therefore, despite de minimis
magnitude ratings, we expect some
consequences to individual humpback,
fin, and minke whales, i.e., leading to a
low impact rating. However, given the
minimal amount of interaction expected
between these species and the survey
activities, and in consideration of the
overall low impact ratings, we find the
take from ION’s planned survey
activities will have a negligible impact
on the humpback whale, fin whale, and
minke whale.
For those species with de minimis
impact ratings we believe that, absent
additional relevant concerns related to
population status or context, the rating
implies that a negligible impact should
be expected as a result of the specified
activity. No such concerns exist for
these species, and we find the take from
ION’s planned survey activities will
have a negligible impact on all stocks of
bottlenose dolphin, two species of
spotted dolphin, rough-toothed dolphin,
striped dolphin, common dolphin,
Clymene dolphin, Risso’s dolphin, and
harbor porpoise.
In summary, based on the analysis
contained herein of the likely effects of
the specified activity on marine
mammals and their habitat, and taking
into consideration the implementation
of the required monitoring and
mitigation measures, we find that the
total marine mammal take from ION’s
survey activities will have a negligible
impact on all affected marine mammal
species or stocks.
Western—Western has planned a 208day survey program, or 57 percent of the
year (slightly more than two seasons).
However, the planned survey would
cover a large spatial extent (i.e., a
majority of the mid- and south Atlantic;
see Figures 1–1 to 1–4 of Western’s
application). Therefore, although the
survey would be long-term (i.e., greater
than one season) in total duration, we
would not expect the duration of effect
to be greater than moderate and
intermittent in any given area. Table 13
displays relevant information leading to
impact ratings for each species resulting
from Western’s survey. In general, we
note that although the temporal and
spatial scale of the planned survey
activity is large, the fact that this mobile
acoustic source would be moving across
large areas (as compared with
geophysical surveys with different
objectives that may require focused
effort over long periods of time in
smaller areas) means that more
individuals may receive limited
exposure to survey noise, versus fewer
individuals receiving more intense
exposure and/or for longer periods of
time. The nature of such potentially
transitory exposure (which we
nevertheless assume here is of moderate
duration and intermittent, versus
isolated) means that the potential
significance of behavioral disruption
and potential for longer-term avoidance
of important areas is limited.
amozie on DSK3GDR082PROD with NOTICES2
TABLE 13—MAGNITUDE AND IMPACT RATINGS, WESTERN
Species
Amount
Spatial extent
Magnitude
rating
Consequences
North Atlantic right whale .....................................
Humpback whale ..................................................
Minke whale ..........................................................
Fin whale ..............................................................
Sperm whale .........................................................
Kogia spp ..............................................................
Beaked whales .....................................................
Rough-toothed dolphin .........................................
Bottlenose dolphin ................................................
Clymene dolphin ...................................................
Atlantic spotted dolphin ........................................
Pantropical spotted dolphin ..................................
Striped dolphin ......................................................
Common dolphin ...................................................
Risso’s dolphin ......................................................
Pilot whales ...........................................................
De minimis ........
De minimis ........
De minimis ........
Low ...................
Moderate ...........
Moderate ...........
Moderate ...........
Low ...................
Moderate ...........
De minimis ........
Moderate ...........
Low ...................
Low ...................
Low ...................
Low ...................
Low ...................
Low-Moderate ..
Low-Moderate ..
Low-High ..........
Low ..................
Moderate ..........
High .................
Moderate ..........
High .................
High .................
High .................
Moderate ..........
High .................
Low ..................
Low-moderate ..
Low-moderate ..
Moderate ..........
De minimis .......
De minimis .......
De minimis .......
Medium ............
High .................
High .................
High .................
High .................
High .................
De minimis .......
High .................
High .................
Medium ............
Medium ............
Medium ............
Medium ............
Medium ..............
Medium ..............
Medium ..............
Medium ..............
Medium ..............
Low .....................
High ....................
Low .....................
Low .....................
Low .....................
Low .....................
Low .....................
Low .....................
Low .....................
Low .....................
Medium ..............
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E:\FR\FM\07DEN2.SGM
07DEN2
Impact rating 1
Low.
Low.
Low.
Moderate.
High.
Moderate.
High.
Moderate.
Moderate.
De minimis.
Moderate.
Moderate.
Low.
Low.
Low.
Moderate.
Federal Register / Vol. 83, No. 235 / Friday, December 7, 2018 / Notices
63373
TABLE 13—MAGNITUDE AND IMPACT RATINGS, WESTERN—Continued
Species
Amount
Spatial extent
Magnitude
rating
Consequences
Harbor porpoise ....................................................
De minimis ........
Low ..................
De minimis .......
Low .....................
Impact rating 1
De minimis
1 Impact
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rating does not indicate whether overall impact to the species or stock is negligible, but is considered with relevant contextual factors
(described generally above and specifically below) in order to ultimately determine whether the effects of the specified activity on the affected
species or stock are negligible.
The North Atlantic right whale is
endangered, has a very low population
size, and faces significant additional
stressors. Therefore, regardless of
impact rating, we believe that the
required mitigation described
previously is critically important in
order for us to make the necessary
finding and it is with consideration of
this mitigation that we find the take
from Western’s survey activities will
have a negligible impact on the North
Atlantic right whale. The fin whale
receives a moderate impact rating
overall, but we expect that for two
seasons (summer and fall) almost no fin
whales will be present in the survey
area. For the remainder of the year, it is
likely that less than one quarter of the
population will be present within the
survey area (Roberts et al., 2016),
meaning that despite medium rankings
for magnitude and likely consequences,
these impacts would be experienced by
only a small subset of the overall
population. In consideration of the
moderate impact rating, the likely
proportion of the population that may
be affected by the specified activities,
and the lack of evidence that the survey
area is host to important behaviors that
may be disrupted, we find the take from
Western’s survey activities will have a
negligible impact on the fin whale.
Magnitude ratings for the sperm
whale and beaked whales are high and,
further, consequence factors reinforce
high impact ratings for both. Magnitude
rating for pilot whales is medium but,
similar to beaked whales, we expect that
compensatory ability will be low (high
consequence rating) due to presumed
residency in areas targeted by the
planned survey—leading to a moderate
impact rating. However, regardless of
impact rating, the consideration of
likely consequences and contextual
factors for all three taxa leads us to
conclude that targeted mitigation is
important to support a finding that the
effects of the survey will have a
negligible impact on these species. As
described previously, sperm whales are
an endangered species with particular
susceptibility to disruption of foraging
behavior, beaked whales are particularly
acoustically sensitive (with presumed
low compensatory ability), and pilot
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whales are sensitive to additional
stressors due to a high degree of
mortality in commercial fisheries (and
also with low compensatory ability).
Finally, due to their acoustic sensitivity,
we have required shutdown of the
acoustic source upon observation of a
beaked whale at extended distance from
the source vessel. In consideration of
the required mitigation, we find the take
from Western’s survey activities will
have a negligible impact on the sperm
whale, beaked whales (i.e., Ziphius
cavirostris and Mesoplodon spp.), and
pilot whales (i.e., Globicephala spp.).
Kogia spp. receive a moderate impact
rating. However, although NMFS does
not currently identify a trend for these
populations, recent survey effort and
stranding data show a simultaneous
increase in at-sea abundance and
strandings, suggesting growing Kogia
spp. abundance (NMFS, 2011; 2013a;
Waring et al., 2007; 2013). Finally, we
expect that Kogia spp. will receive
subsidiary benefit from the mitigation
targeted for sperm whales, beaked
whales, and pilot whales and, although
minimally effective due to the difficulty
of at-sea observation of Kogia spp., we
have required shutdown of the acoustic
source upon observation of Kogia spp. at
extended distance from the source
vessel. In consideration of these
factors—likely population increase and
required mitigation—we find the take
from Western’s survey activities will
have a negligible impact on Kogia spp.
As described in the introduction to
this analysis, it is assumed that likely
consequences are somewhat higher for
species of mysticete whales (lowfrequency hearing specialists) due to the
greater potential for masking impacts at
longer ranges than other taxa and at
frequencies that overlap a larger portion
of both their hearing and vocalization
ranges. Therefore, despite de minimis
magnitude ratings, we expect some
consequences to individual humpback
and minke whales, i.e., leading to a low
impact rating. However, given the
minimal amount of interaction expected
between these species and the survey
activities, and in consideration of the
overall low impact ratings, we find the
take from Western’s planned survey
activities will have a negligible impact
PO 00000
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on the humpback whale and minke
whale.
Despite medium to high magnitude
ratings (with the exception of the
Clymene dolphin), remaining delphinid
species receive low to moderate impact
ratings due to consequences relating to
a lack of propensity for behavioral
disruption due to airgun survey activity
and our expectation that these species
would generally have relatively high
compensatory ability. In addition,
contextually these species do not have
significant issues relating to population
status or context. Many oceanic
delphinid species are generally more
associated with dynamic oceanographic
characteristics rather than static
physical features, and those species
(such as common dolphin) with
substantial distribution to the north of
the survey area would likely be little
affected at the population level by the
specified activity. For example, both
species of spotted dolphin and the
offshore stock of bottlenose dolphin
range widely over slope and abyssal
waters (e.g., Waring et al., 2014; Hayes
et al., 2017; Roberts et al., 2016), while
the rough-toothed dolphin does not
appear bound by water depth in its
range (Ritter, 2002; Wells et al., 2008).
Our required mitigation largely
eliminates potential effects to depleted
coastal stocks of bottlenose dolphin. We
also expect that meaningful subsidiary
benefit will accrue to certain species
from the mitigation targeted for sperm
whales, beaked whales, and pilot
whales, most notably to species
presumed to have greater association
with shelf break waters north of Cape
Hatteras (e.g., offshore bottlenose
dolphins, common dolphins, and
Risso’s dolphins). In consideration of
these factors—overall impact ratings
and context including required
mitigation—we find the take from
Western’s survey activities will have a
negligible impact on most remaining
delphinid species (i.e., all stocks of
bottlenose dolphin, two species of
spotted dolphin, rough-toothed dolphin,
striped dolphin, common dolphin, and
Risso’s dolphin).
For those species with de minimis
impact ratings we believe that, absent
additional relevant concerns related to
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population status or context, the rating
implies that a negligible impact should
be expected as a result of the specified
activity. No such concerns exist for
these species, and we find the take from
Western’s survey activities will have a
negligible impact on the Clymene
dolphin and harbor porpoise.
In summary, based on the analysis
contained herein of the likely effects of
the specified activity on marine
mammals and their habitat, and taking
into consideration the implementation
of the required monitoring and
mitigation measures, we find that the
total marine mammal take from
Western’s survey activities will have a
negligible impact on all affected marine
mammal species or stocks.
CGG—CGG has planned an
approximately 155-day survey program,
or 42 percent of the year (approximately
two seasons). However, the planned
survey would cover a large spatial
extent (i.e., a majority of the mid- and
south Atlantic; see Figure 3 of CGG’s
application). Therefore, although the
survey would be long-term (i.e., greater
than one season) in total duration, we
would not expect the duration of effect
to be greater than moderate and
intermittent in any given area. Table 14
displays relevant information leading to
impact ratings for each species resulting
from CGG’s survey. In general, we note
that although the temporal and spatial
scale of the planned survey activity is
large, the fact that this mobile acoustic
source would be moving across large
areas (as compared with geophysical
surveys with different objectives that
may require focused effort over long
periods of time in smaller areas) means
that more individuals may receive
limited exposure to survey noise, versus
fewer individuals receiving more
intense exposure and/or for longer
periods of time. The nature of such
potentially transitory exposure means
that the potential significance of
behavioral disruption and potential for
longer-term avoidance of important
areas is limited.
TABLE 14—MAGNITUDE AND IMPACT RATINGS, CGG
Species
Amount
Spatial extent
Magnitude
rating
Consequences
North Atlantic right whale .....................................
Humpback whale ..................................................
Minke whale ..........................................................
Fin whale ..............................................................
Sperm whale .........................................................
Kogia spp ..............................................................
Beaked whales .....................................................
Rough-toothed dolphin .........................................
Bottlenose dolphin ................................................
Clymene dolphin ...................................................
Atlantic spotted dolphin ........................................
Pantropical spotted dolphin ..................................
Striped dolphin ......................................................
Common dolphin ...................................................
Risso’s dolphin ......................................................
Pilot whales ...........................................................
Harbor porpoise ....................................................
De minimis ........
De minimis ........
De minimis ........
De minimis ........
Low ...................
Low ...................
Low ...................
Moderate ...........
Low ...................
High ...................
Low ...................
Moderate ...........
De minimis ........
De minimis ........
De minimis ........
Low ...................
De minimis ........
Low-Moderate ..
Low-Moderate ..
Low-High ..........
Low ..................
Moderate ..........
High .................
Moderate ..........
High .................
High .................
High .................
Moderate ..........
High .................
Low ..................
Low-moderate ..
Low-moderate ..
Moderate ..........
Low ..................
De minimis .......
De minimis .......
De minimis .......
De minimis .......
Medium ............
High .................
Medium ............
High .................
High .................
High .................
Medium ............
High .................
De minimis .......
De minimis .......
De minimis .......
Medium ............
De minimis .......
Medium ..............
Medium ..............
Medium ..............
Medium ..............
Medium ..............
Low .....................
High ....................
Low .....................
Low .....................
Low .....................
Low .....................
Low .....................
Low .....................
Low .....................
Low .....................
Medium ..............
Low .....................
Impact rating 1
Low.
Low.
Low.
Low.
Moderate.
Moderate.
Moderate.
Moderate.
Moderate.
Moderate.
Low.
Moderate.
De minimis.
De minimis.
De minimis.
Moderate.
De minimis.
amozie on DSK3GDR082PROD with NOTICES2
1 Impact rating does not indicate whether overall impact to the species or stock is negligible, but is considered with relevant contextual factors
(described generally above and specifically below) in order to ultimately determine whether the effects of the specified activity on the affected
species or stock are negligible.
The North Atlantic right whale is
endangered, has a very low population
size, and faces significant additional
stressors. Therefore, regardless of
impact rating, we believe that the
required mitigation described
previously is critically important in
order for us to make the necessary
finding and it is with consideration of
this mitigation that we find the take
from CGG’s survey activities will have
a negligible impact on the North
Atlantic right whale.
Magnitude ratings for the sperm
whale and beaked whales are medium;
however, consequence factors are
medium and high, respectively.
Magnitude rating for pilot whales is
medium but, similar to beaked whales,
we expect that compensatory ability
will be low (high consequence rating)
due to presumed residency in areas
targeted by the planned survey—leading
to a moderate impact rating. However,
regardless of impact rating, the
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consideration of likely consequences
and contextual factors for all three taxa
leads us to conclude that targeted
mitigation is important to support a
finding that the effects of the survey will
have a negligible impact on these
species. As described previously, sperm
whales are an endangered species with
particular susceptibility to disruption of
foraging behavior, beaked whales are
particularly acoustically sensitive (with
presumed low compensatory ability),
and pilot whales are sensitive to
additional stressors due to a high degree
of mortality in commercial fisheries
(and also with low compensatory
ability). Finally, due to their acoustic
sensitivity, we require shutdown of the
acoustic source upon detection of a
beaked whale at extended distance from
the source vessel. In consideration of
the required mitigation, we find the take
from CGG’s survey activities will have
a negligible impact on the sperm whale,
beaked whales (i.e., Ziphius cavirostris
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Fmt 4701
Sfmt 4703
and Mesoplodon spp.), and pilot whales
(i.e., Globicephala spp.).
Kogia spp. receive a moderate impact
rating. However, although NMFS does
not currently identify a trend for these
populations, recent survey effort and
stranding data show a simultaneous
increase in at-sea abundance and
strandings, suggesting growing Kogia
spp. abundance (NMFS, 2011; 2013a;
Waring et al., 2007; 2013). Finally, we
expect that Kogia spp. will receive
subsidiary benefit from the required
mitigation targeted for sperm whales,
beaked whales, and pilot whales and,
although minimally effective due to the
difficulty of at-sea observation of Kogia
spp., we have required shutdown of the
acoustic source upon observation of
Kogia spp. at extended distance from the
source vessel. In consideration of these
factors—likely population increase and
required mitigation—we find the take
from CGG’s survey activities will have
a negligible impact on Kogia spp.
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As described in the introduction to
this analysis, it is assumed that likely
consequences are somewhat higher for
species of mysticete whales (lowfrequency hearing specialists) due to the
greater potential for masking impacts at
longer ranges than other taxa and at
frequencies that overlap a larger portion
of both their hearing and vocalization
ranges. Therefore, despite de minimis
magnitude ratings, we expect some
consequences to individual humpback,
fin, and minke whales, i.e., leading to a
low impact rating. However, given the
minimal amount of interaction expected
between these species and the survey
activities, and in consideration of the
overall low impact ratings, we find the
take from CGG’s planned survey
activities will have a negligible impact
on the humpback whale, fin whale, and
minke whale.
Despite medium to high magnitude
ratings (with some exceptions), most
remaining delphinid species receive low
to moderate impact ratings due to
consequences relating to a lack of
propensity for behavioral disruption
due to airgun survey activity and our
expectation that these species would
generally have relatively high
compensatory ability. In addition,
contextually these species do not have
significant issues relating to population
status or context. Many oceanic
delphinid species are generally more
associated with dynamic oceanographic
characteristics rather than static
physical features, and those species
(such as common dolphin) with
substantial distribution to the north of
the survey area would likely be little
affected at the population level by the
specified activity. For example, both
species of spotted dolphin and the
offshore stock of bottlenose dolphin
range widely over slope and abyssal
waters (e.g., Waring et al., 2014; Hayes
et al., 2017; Roberts et al., 2016), while
the rough-toothed dolphin does not
appear bound by water depth in its
range (Ritter, 2002; Wells et al., 2008).
Our required mitigation largely
eliminates potential effects to depleted
coastal stocks of bottlenose dolphin. We
also expect that meaningful subsidiary
benefit will accrue to certain species
from the mitigation targeted for sperm
whales, beaked whales, and pilot
whales, most notably to species
presumed to have greater association
with shelf break waters north of Cape
Hatteras (e.g., offshore bottlenose
dolphins). In consideration of these
factors—overall impact ratings and
context including required mitigation—
we find the take from CGG’s survey
activities will have a negligible impact
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on remaining delphinid species (i.e., all
stocks of bottlenose dolphin, two
species of spotted dolphin, roughtoothed dolphin, and Clymene dolphin).
For those species with de minimis
impact ratings we believe that, absent
additional relevant concerns related to
population status or context, the rating
implies that a negligible impact should
be expected as a result of the specified
activity. No such concerns exist for
these species, and we find the take from
CGG’s survey activities will have a
negligible impact on the common
dolphin, striped dolphin, Risso’s
dolphin, and harbor porpoise.
In summary, based on the analysis
contained herein of the likely effects of
the specified activity on marine
mammals and their habitat, and taking
into consideration the implementation
of the required monitoring and
mitigation measures, we find that the
total marine mammal take from CGG’s
survey activities will have a negligible
impact on all affected marine mammal
species or stocks.
Small Numbers Analyses
The MMPA does not define ‘‘small
numbers.’’ NMFS’s and the U.S. Fish
and Wildlife Service’s 1989
implementing regulations defined small
numbers as a portion of a marine
mammal species or stock whose taking
would have a negligible impact on that
species or stock. This definition was
invalidated in Natural Resources
Defense Council v. Evans, 279
F.Supp.2d 1129 (2003) (N.D. Cal. 2003),
based on the court’s determination that
the regulatory definition of small
numbers was improperly conflated with
the regulatory definition of ‘‘negligible
impact,’’ which rendered the small
numbers standard superfluous. As the
court observed, ‘‘the plain language
indicates that small numbers is a
separate requirement from negligible
impact.’’ Since that time, NMFS has not
applied the definition found in its
regulations. Rather, consistent with
Congress’ pronouncement that small
numbers is not a concept that can be
expressed in absolute terms (House
Committee on Merchant Marine and
Fisheries Report No. 97–228 (September
16, 1981)), NMFS makes its small
numbers findings based on an analysis
of whether the number of individuals
authorized to be taken annually from a
specified activity is small relative to the
stock or population size. The Ninth
Circuit has upheld a similar approach.
See Center for Biological Diversity v.
Salazar, No. 10–35123, 2012 WL
3570667 (9th Cir. Aug. 21, 2012).
However, we have not historically
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63375
indicated what we believe the upper
limit of small numbers is.
To maintain an interpretation of small
numbers as a proportion of a species or
stock that does not conflate with
negligible impact, we use the following
framework. A plain reading of ‘‘small’’
implies as corollary that there also
could be ‘‘medium’’ or ‘‘large’’ numbers
of animals from the species or stock
taken. We therefore use a simple
approach that establishes equal bins
corresponding to small, medium, and
large proportions of the population
abundance.
NMFS’s practice for making small
numbers determinations is to compare
the number of individuals estimated
and authorized to be taken (often using
estimates of total instances of take,
without regard to whether individuals
are exposed more than once) against the
best available abundance estimate for
that species or stock. We note, however,
that although NMFS’s implementing
regulations require applications for
incidental take to include an estimate of
the marine mammals to be taken, there
is nothing in paragraphs (A) or (D) of
section 101(a)(5) that requires NMFS to
quantify or estimate numbers of marine
mammals to be taken for purposes of
evaluating whether the number is small.
(See CBD v. Salazar.) While it can be
challenging to predict the numbers of
individual marine mammals that will be
taken by an activity (again, many
models calculate instances of take and
are unable to account for repeated
exposures of individuals), in some cases
we are able to generate a reasonable
estimate utilizing a combination of
quantitative tools and qualitative
information. When it is possible to
predict with relative confidence the
number of individual marine mammals
of each species or stock that are likely
to be taken, the small numbers
determination should be based directly
upon whether or not these estimates
exceed one third of the stock
abundance. In other words, consistent
with past practice, when the estimated
number of individual animals taken
(which may or may not be assumed as
equal to the total number of takes,
depending on the available information)
is up to, but not greater than, one third
of the species or stock abundance,
NMFS will determine that the numbers
of marine mammals taken of a species
or stock are small.
Another circumstance in which
NMFS considers it appropriate to make
a small numbers finding is in the case
of a species or stock that may
potentially be taken but is either rarely
encountered or only expected to be
taken on rare occasions. In that
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circumstance, one or two assumed
encounters with a group of animals
(meaning a group that is traveling
together or aggregated, and thus exposed
to a stressor at the same approximate
time) should reasonably be considered
small numbers, regardless of
consideration of the proportion of the
stock (if known), as rare encounters
resulting in take of one or two groups
should be considered small relative to
the range and distribution of any stock.
In summary, when quantitative take
estimates of individual marine
mammals are available or inferable
through consideration of additional
factors, and the number of animals
spinner dolphin, and white-sided
dolphin, we authorize take resulting
from a single exposure of one group of
each species or stock, as appropriate
(using average group size), for each
applicant. We believe that a single
incident of take of one group of any of
these species represents take of small
numbers for that species. Therefore, for
each applicant, based on the analyses
contained herein of their specified
activity, we find that small numbers of
marine mammals will be taken for each
of these 11 affected species or stocks for
each specified activity. We do not
discuss these 11 species further in the
applicant-specific analyses that follow.
taken is one third or less of the best
available abundance estimate for the
species or stock, NMFS considers it to
be of small numbers. NMFS may
appropriately find that one or two
predicted group encounters will result
in small numbers of take relative to the
range and distribution of a species,
regardless of the estimated proportion of
the abundance.
Please see Table 15 for information
relating to the basis for our small
numbers analyses. For the sei whale,
Bryde’s whale, blue whale, northern
bottlenose whale, Fraser’s dolphin,
melon-headed whale, false killer whale,
pygmy killer whale, killer whale,
TABLE 15—TOTAL INSTANCES OF TAKE AUTHORIZED 1 AND PROPORTION OF BEST ABUNDANCE ESTIMATE 2
Common name
North Atlantic right whale ..
Humpback whale ...............
Minke whale ......................
Fin whale ...........................
Sperm whale .....................
Kogia spp ..........................
Beaked whales ..................
Rough-toothed dolphin ......
Bottlenose dolphin .............
Clymene dolphin ...............
Atlantic spotted dolphin .....
Pantropical spotted dolphin
Striped dolphin ..................
Common dolphin ...............
Risso’s dolphin ..................
Globicephala spp ..............
Harbor porpoise ................
Abundance
estimate 4
458
5 2,002
20,741
5 6,582
5 9,649
3,785
6 25,284
7 845
5 149,785
7 24,018
6 107,100
7 7,217
6 158,258
173,486
5 19,437
6 34,531
5 50,406
Spectrum 8
Take
TGS 3
%
6
45
423
337
1,077
205
3,357
201
37,562
6,459
16,926
1,632
8,022
11,087
755
2,765
627
Take
1
2
2
5
11
5
13
24
25
27
16
23
5
6
4
8
1
9
60
212
1,144
3,579
1,221
12,072
261
40,595
821
41,222
1,470
23,418
52,728
3,241
8,902
325
ION
%
Take
2
3
1
17
37
32
48
31
27
3
38
20
15
30
17
26
1
2
7
12
5
16
30
490
14
2,599
252
568
78
162
372
90
199
21
Western
%
Take
<1
<1
<1
<1
<1
1
2
2
2
1
1
1
<1
<1
<1
1
<1
4
49
100
537
1,941
572
4,960
123
23,600
391
18,724
690
8,845
20,683
1,608
4,682
155
CGG
%
Take
1
2
<1
8
20
15
20
15
16
2
17
10
6
12
8
14
<1
2
7
128
49
1,304
240
3,511
177
9,063
6,382
6,596
1,566
6,328
6,026
809
1,964
30
%
<1
<1
1
1
14
6
14
21
6
27
6
22
4
3
4
6
<1
1 Total
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take authorized includes take by Level A and Level B harassment. Please see Table 6 for details.
2 Species for which take resulting from a single exposure of one group of each species or stock are not included in this table. Please see discussion preceding this
table.
3 Additional analysis was conducted to specify the number of individuals taken for TGS. Please see discussion below and Table 16.
4 Best abundance estimate; please see discussion under ‘‘Description of Marine Mammals in the Area of the Specified Activities.’’ For most taxa, the best abundance estimate for purposes of comparison with take estimates is considered here to be the model-predicted abundance (Roberts et al., 2016). For these taxa,
model-predicted abundances within the EEZ and estimates for the portion of the specific geographic region beyond the EEZ are combined to obtain the total abundance. For those taxa where a density surface model was produced, maximum monthly abundance was considered appropriate for some, and for others the maximum mean seasonal abundance was used as a precaution. For those taxa where only a stratified model was produced, only mean annual abundance is available.
For several taxa, other abundance estimates were deemed most appropriate, as described previously in this notice.
5 Maximum monthly abundance.
6 Maximum seasonal abundance.
7 Mean annual abundance.
8 Small numbers analyses were completed prior to receipt of a modified survey plan from Spectrum and subsequent revision of authorized take numbers reflecting
the modification. Here, we retain the original take estimates for Spectrum in context of the small numbers analysis described below. Please see ‘‘Spectrum Survey
Plan Modification,’’ below, for additional information describing the modified survey plan, findings made in context of the analysis presented below, and authorized
take for Spectrum (Table 17).
As discussed previously, the MMPA
does not define small numbers. NMFS
compares the estimated numbers of
individuals expected to be taken (when
available; often take estimates are
presented as estimated instances of take)
to the most appropriate estimation of
the relevant species or stock size in our
determination of whether an
authorization is limited to small
numbers of marine mammals, i.e., less
than one-third of the most appropriate
abundance estimate (Table 15). In the
Notice of Proposed Authorization, we
proposed to limit the authorization of
take to approximately one-third of the
most appropriate stock abundance
estimate, assuming no other relevant
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factors that provide more context for the
estimate (e.g., information that the take
estimate numbers represent instances of
multiple exposures of the same
animals). Further, we proposed that, in
order to limit actual take to this
proportion of estimated stock
abundance, we would require monthly
reporting from those applicants with
predicted exposures of any species
exceeding this threshold. Those interim
reports would include corrected
numbers of marine mammals ‘‘taken’’
and, upon reaching the pre-determined
take threshold, any issued IHA would
be withdrawn.
However, as discussed elsewhere in
this notice (including in ‘‘Comments
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and Responses’’), we received numerous
comments criticizing this approach.
Notably, comments indicated that the
pre-determined threshold (described in
our Notice of Proposed IHAs as30
percent) was arbitrary and not rooted in
any meaningful biological
consideration, and that the proposal—
i.e., to limit the actual take
authorization to less than what was
estimated in terms of potential
exposures, require a novel reporting
scheme, and potentially withdraw IHAs
if the threshold was crossed—was
impracticable. However, in this Notice
we have more fully described and
clarified our approach to small
numbers, and used this approach for
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issuance of the IHAs. As a result of the
concerns presented by applicants and
commenters regarding the justification
for and practicability of our proposal,
we reconsidered the available
information and re-evaluated and
refined our small numbers analyses, as
described next. With regard to use of the
most appropriate population abundance
(Table 15), please see additional
discussion under ‘‘Description of
Marine Mammals in the Area of the
Specified Activities.’’
The number of exposures presented in
Table 15 represent the estimated
number of instantaneous instances in
which an individual from each species
or stock would be exposed to sound
fields from airgun surveys at or above
the 160 dB rms threshold. They do not
necessarily represent the estimated
number of individuals of each species
that would be exposed, nor do they
provide information on the duration of
the exposure. In this case, the likelihood
that any individual of a given species is
exposed more than once is low due to
the movement of both the vessels and
the animals themselves. That said, for
species where the estimated exposure
numbers are higher compared to the
population abundance, we assume that
some individuals may be exposed more
than once, meaning the exposures given
in Table 15 overestimate the numbers of
individuals that would be exposed.
Applicant-specific analyses follow.
Spectrum—The total amount of taking
assessed for all affected stocks on the
basis of Spectrum’s original survey plan
ranges from 1 to 27 percent of the most
appropriate population abundance
estimate, and is therefore less than the
appropriate small numbers threshold
(i.e., one-third of the most appropriate
population abundance estimate). These
proportions are considered
overestimates with regard to the small
numbers findings, as they likely
represent multiple exposures of some of
the same individuals for some stocks.
However, we do not have sufficient
information on which to base an
estimate of individuals taken versus
instances of take. Please see ‘‘Spectrum
Survey Plan Modification,’’ below, for
additional information describing the
modified survey plan, findings made in
context of the analysis presented here,
and authorized take for Spectrum (Table
17).
Based on the analysis contained
herein of Spectrum’s specified activity,
the required monitoring and mitigation
measures, and the anticipated take of
marine mammals, we find that small
numbers of marine mammals will be
taken relative to the population sizes of
the affected species or stocks.
TGS—The total amount of taking (in
consideration of instances of take)
authorized for a majority of affected
stocks ranges from 1 to 32 percent of the
most appropriate population abundance
estimate, and is therefore less than the
appropriate small numbers threshold
(i.e., one-third of the most appropriate
population abundance estimate). The
total amount of taking (in consideration
of instances of take) authorized for the
sperm whale, beaked whales, and the
Atlantic spotted dolphin is higher than
the threshold. In this case, we have
information available to distinguish
between an estimate of individuals
taken versus instances of take.
TGS is the only applicant that
provided an analysis of estimated
individuals exposed versus instances of
exposure (see Table 6–5 of TGS’s
application). As described in the
introduction to this section, the number
of individuals taken (versus total
instances of take), is the relevant metric
for comparison to population
abundance in a small numbers analysis.
We note, though, that total instances of
take are routinely used to evaluate small
numbers when data to distinguish
individuals is not available, and we
further note the conservativeness of the
assumption, as the number of total
instances of take equates to the highest
possible number of individuals. For
example, in some cases the total number
of takes may exceed the number of
individuals in a population abundance,
meaning there are multiple exposures of
at least some animals.
We do not typically attempt to
quantitatively assess this comparison of
individuals taken versus instances of
take when we do not have direct
information regarding individuals
exposed (e.g., we know that only a
specific sub-population is potentially
exposed or we know that uniquely
identified individuals are exposed);
therefore, we did not initially make use
of the information provided by TGS in
their application, instead proposing the
take cap and reporting scheme
described in the introduction to this
section. As described above,
commenters indicated that our proposed
approach was flawed and, therefore, we
further evaluated the available
information.
The conceptual approach to the
analysis involves a comparison of total
ensonified area to the portion of that
total area that is ensonified more than
once. For TGS, 84 percent of the total
ensonified area is area that is ensonified
more than once, i.e., ‘‘overlap.’’ In a
static density model, the same animals
occur in the overlap regardless of the
time elapsed between the first and
second exposure. If animals are static in
space in the model, they are re-exposed
in the model every time there is overlap.
When overlap is counted toward the
evaluation of small numbers (i.e.,
percent of the abundance that is
‘‘taken’’), it effectively raises the total
abundance possible in the model,
creating a situation in which one could
theoretically take more than the
abundance to which one is comparing.
This does not make sense from the
perspective of comparing numbers of
individuals taken to total abundance.
Although portions of the overlap may be
ensonified more than twice, we
conservatively assume a maximum of
one repeat ensonification.
The number of individuals potentially
taken (versus total incidents of take) can
then be determined using the following
equation: (Numerical Output of the
Model)¥(0.84 * Numerical Output of
the Model) + 0.5 * (0.84 * Numerical
Output of the Model). This may be
simplified as: 0.58 * Numerical Output
of the Model. ‘‘Numerical output of the
model’’ refers to the estimated total
incidents of take. As we stated in the
introduction to this section, where there
are relatively few total takes, it is more
likely that all takes occur to new
individuals, though this is dependent
on actual distribution and movement of
animals in relation to the survey vessel.
While there is no clear threshold as to
what level of total takes indicates a
likelihood of repeat taking of
individuals, here we assume that total
taking of a moderate or high magnitude
(consistent with our approach to
assessing magnitude in the negligible
impact analysis framework; see
‘‘Negligible Impact Analyses and
Determinations’’), i.e., greater than 15
percent, is required for repeat taking of
individuals to be likely and applied this
analysis only to those stocks.
TABLE 16—ANALYSIS OF INDIVIDUALS TAKEN VERSUS TOTAL TAKES, TGS
Abundance
estimate
Common name
Fin whale ...........................................................................................
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Total take
1,144
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Individuals
taken
%
17
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664
07DEN2
Individuals
taken once
%
10
480
Individuals
taken twice
184
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TABLE 16—ANALYSIS OF INDIVIDUALS TAKEN VERSUS TOTAL TAKES, TGS—Continued
Abundance
estimate
Common name
Sperm whale .....................................................................................
Kogia spp. .........................................................................................
Beaked whales ..................................................................................
Rough-toothed dolphin ......................................................................
Bottlenose dolphin .............................................................................
Atlantic spotted dolphin .....................................................................
Pantropical spotted dolphin ...............................................................
Common dolphin ...............................................................................
Risso’s dolphin ..................................................................................
Globicephala spp. .............................................................................
This approach also allows us to
estimate the number of individuals that
we assume to be taken once and the
number assumed to be taken twice. As
we noted previously, although it is
possible that some individuals may be
taken more than twice, we assume a
maximum of one repeat ensonification
(a conservative assumption in this small
numbers analysis context). For example,
if there are 1,144 total takes of fin
whales, with 664 total individuals
taken, and where:
amozie on DSK3GDR082PROD with NOTICES2
a = number of animals with single take; b =
number of animals with double take,
then: a + b = 664 and 2*a + b = 1,144 and,
therefore, 2*a + 664¥a = 1,144. In this
example for fin whales, we assume that
480 individuals are taken twice and 184
individuals are taken once. (Note that
values given in Table 16 for individuals
taken once versus twice may not sum to
the value given for total individuals
taken due to rounding.)
In summary, for those stocks for
which we assume each authorized take
represents a new individual, the total
amount of taking authorized ranges from
1 to 15 percent of the most appropriate
population abundance estimate (Table
15), and is therefore less than the
appropriate small numbers threshold
(i.e., one-third of the most appropriate
population abundance estimate). For
those stocks for which we assessed the
number of expected individuals taken,
the total amount of taking authorized
ranges from 10 to 28 percent of the most
appropriate population abundance
estimate (Table 16), and is therefore less
than the appropriate small numbers
threshold (i.e., one-third of the most
appropriate population abundance
estimate). Based on the analysis
contained herein of TGS’s specified
activity, the required monitoring and
mitigation measures, and the
anticipated take of marine mammals, we
find that small numbers of marine
mammals will be taken relative to the
population sizes of the affected species
or stocks.
ION—The total amount of taking
authorized for all affected stocks ranges
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9,649
3,785
25,284
845
149,785
107,100
7,217
173,486
19,437
34,531
Total take
Individuals
taken
%
3,579
1,221
12,072
261
40,595
41,222
1,470
52,728
3,241
8,902
37
32
48
31
27
38
20
30
17
26
from less than 1 to 4 percent of the most
appropriate population abundance
estimate, and is therefore less than the
appropriate small numbers threshold
(i.e., one-third of the most appropriate
population abundance estimate).
Based on the analysis contained
herein of ION’s specified activity, the
required monitoring and mitigation
measures, and the anticipated take of
marine mammals, we find that small
numbers of marine mammals will be
taken relative to the population sizes of
the affected species or stocks.
Western—The total amount of taking
authorized for all affected stocks ranges
from less than 1 to 20 percent of the
most appropriate population abundance
estimate, and is therefore less than the
appropriate small numbers threshold
(i.e., one-third of the most appropriate
population abundance estimate). These
proportions are considered
overestimates with regard to the small
numbers findings, as they likely
represent multiple exposures of some of
the same individuals for some stocks.
However, we do not have sufficient
information on which to base an
estimate of individuals taken versus
instances of take.
Based on the analysis contained
herein of Western’s specified activity,
the required monitoring and mitigation
measures, and the anticipated take of
marine mammals, we find that small
numbers of marine mammals will be
taken relative to the population sizes of
the affected species or stocks.
CGG—The total amount of taking
authorized for all affected stocks ranges
from less than 1 to 27 percent of the
most appropriate population abundance
estimate, and is therefore less than the
appropriate small numbers threshold
(i.e., one-third of the most appropriate
population abundance estimate). These
proportions are considered
overestimates with regard to the small
numbers findings, as they likely
represent multiple exposures of some of
the same individuals for some stocks.
However, we do not have sufficient
information on which to base an
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2,076
708
7,002
151
23,545
23,909
853
30,582
1,880
5,163
Individuals
taken once
%
22
19
28
18
16
22
12
18
10
15
Individuals
taken twice
1,503
513
5,070
110
17,050
17,313
617
22,146
1,361
3,739
573
195
1,932
42
6,495
6,596
235
8,436
519
1,424
estimate of individuals taken versus
instances of take.
Based on the analysis contained
herein of CGG’s specified activity, the
required monitoring and mitigation
measures, and the anticipated take of
marine mammals, we find that small
numbers of marine mammals will be
taken relative to the population sizes of
the affected species or stocks.
Impact on Availability of Affected
Species for Taking for Subsistence Uses
There are no relevant subsistence uses
of marine mammals implicated by these
actions. Therefore, relevant to the
Spectrum, TGS, ION, CGG, and Western
IHAs, we have determined that the total
taking of affected species or stocks
would not have an unmitigable adverse
impact on the availability of such
species or stocks for taking for
subsistence purposes.
Spectrum Survey Plan Modification
As described earlier in this notice,
Spectrum’s proposed survey plan
described in our Notice of Proposed
IHAs included ∼21,635 km of survey
line (see Figure 1 of Spectrum’s
application). However, on June 4, 2018,
Spectrum notified NMFS of a
modification to their survey plan.
NMFS’s understanding is this
modification is based on a voluntary
collaborative effort between Spectrum
and TGS, another IHA applicant, to
reduce duplication of effort and
expense. Subsequently, on June 26,
2018, Spectrum submitted a final,
revised modified survey plan. The
modified survey plan occurs roughly
within the same survey ‘‘footprint’’ and
consists of ∼13,766 km of survey line
(see Figure provided on p. 2 of
Spectrum’s letter notifying us of their
intent to modify their survey plan).
Therefore, the modified survey plan
represents an approximate 36 percent
decrease in total survey line. With this
reduction in survey effort, Spectrum
now estimates that the survey plan will
require approximately 108 days of
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operations (previously estimated as 165
days of operations).
The changes to the survey plan, in
summary, include the following: (1)
Rotated the survey grid by
approximately 5 degrees; (2) trimmed
lines from most time-area restrictions;
(3) removed certain lines; and (4) shifted
certain lines. The figure provided on p.
3 of Spectrum’s letter notifying us of
their intent to modify their survey plan
shows an overlay of the modified survey
plan (red lines) with the previously
proposed survey plan (black lines).
Following receipt of the notification
from Spectrum, we evaluated the
potential effect of the change through
use of a spatial analysis. In summary,
we compared marine mammal densities
within assumed ensonified areas
associated with the original survey
tracklines and associated with the
modified survey tracklines. This
allowed us to produce a ratio of the
expected takes by Level B harassment
from the modified survey to the original
survey and, therefore, to evaluate the
degree of change in terms of take. In
conducting this evaluation, we used
mean marine mammal densities over the
21 modeling areas or zones (extracted
from Roberts et al. (2016)), as described
previously in ‘‘Estimated Take.’’
Detailed steps of the evaluation are as
follows:
• Obtain trackline lengths for each
relevant season and zone for proposed
(i.e., the original) and modified
Spectrum tracklines;
• Multiply trackline lengths by mean
buffer widths for each zone to get area
surveyed for both proposed and
modified tracklines;
• Multiply these areas surveyed
within each zone by each species
density to get raw take by zone for
proposed and modified tracklines for
each species (accounting for
implementation of North Atlantic right
whale time-area restriction, in effect out
to 90 km from shore from November
through April);
• Create ratio of the expected take
from the modified tracklines to the
proposed tracklines; and
• Multiply this ratio by the originally
proposed take numbers to obtain revised
take numbers.
However, note that we did not follow
this process (i.e., developing a ratio for
use in ‘‘correcting’’ the original take
number) for North Atlantic right whales.
Instead, we performed an identical
analysis as that described previously in
‘‘Description of Exposure Estimates—
North Atlantic Right Whale,’’ producing
a new take estimate for this species
(Table 17).
The results of this evaluation in terms
of take numbers are shown in Table 17.
Our analysis of the potential for
auditory injury of mid-frequency
cetaceans remains the same and,
therefore, the amount of take by Level
A harassment for these species is
unchanged. For low-frequency
cetaceans, the reduction in total survey
line reduces the likely potential that
take by Level A harassment would
occur. The total amount of survey line
in the modified survey plan is similar to
that proposed by ION and, in fact,
Spectrum’s estimated auditory injury
zone for low-frequency cetaceans is
slightly smaller than ION’s. Therefore,
we adopt the logic presented previously
for ION in revising the authorized take
by Level A harassment for lowfrequency cetaceans (see ‘‘Estimated
Take’’ for more detail). For highfrequency cetaceans, we revise the take
authorized by Level A harassment
according to the same procedure
described previously in ‘‘Estimated
Take.’’ For rarely occurring species (i.e.,
sei whale, Bryde’s whale, blue whale,
northern bottlenose whale, Fraser’s
dolphin, melon-headed whale, false
killer whale, pygmy killer whale, killer
whale, spinner dolphin, and whitesided dolphin), we retain our take
authorization of a single exposure of one
group of each species or stock, as
appropriate (using average group size).
Therefore, our original analysis is
retained for these species or stocks and
we do not address them here.
TABLE 17—TAKE ESTIMATES ASSOCIATED WITH PROPOSED AND MODIFIED TRACKLINES AND PROPORTION OF BEST
ABUNDANCE ESTIMATE
Proposed tracklines
Modified tracklines
Reduction
in total
authorized
take
(%)
Common name
Level A
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North Atlantic right whale .........................
Humpback whale .....................................
Minke whale .............................................
Fin whale ..................................................
Sperm whale ............................................
Kogia spp. ................................................
Beaked whales .........................................
Rough-toothed dolphin .............................
Common bottlenose dolphin ....................
Clymene dolphin ......................................
Atlantic spotted dolphin ............................
Pantropical spotted dolphin .....................
Striped dolphin .........................................
Common dolphin ......................................
Risso’s dolphin .........................................
Pilot whales ..............................................
Harbor porpoise .......................................
Total authorized take for all species
shown in Table 17 decreased. The
modified survey plan largely remains
within the footprint of the proposed
survey plan, with the only notable
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Level B
0
4
4
4
0
5
0
0
0
0
0
0
0
0
0
0
16
%
6
41
419
333
1,077
200
3,357
201
37,562
6,459
16,926
1,632
8,022
11,087
755
2,765
611
Level A
1
2
2
5
11
5
13
24
25
27
16
23
5
6
4
8
1
change being the reduction of total
survey line and the removal of survey
line from certain areas within that
footprint, including, importantly, the
total removal of lines from within our
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Level B
0
2
2
2
0
3
0
0
0
0
0
0
0
0
0
0
8
2
19
252
163
684
125
2,291
117
14,938
4,045
8,466
1,017
5,144
6,008
414
1,591
355
%
<1
1
1
3
7
3
9
14
10
17
8
14
3
3
2
5
1
67
53
40
51
36
38
32
42
60
37
50
38
36
46
45
42
42
designated seasonal ‘‘Hatteras and
North’’ time-area restriction along the
shelf break off of Cape Hatteras (Area
#4; Figure 4). This area constitutes some
of the most important marine mammal
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habitat within the specific geographical
region.
As previously described in
‘‘Negligible Impact Analyses and
Determinations,’’ we have determined
on the basis of Spectrum’s proposed
survey plan that the likely effects of the
(previously described) specified activity
on marine mammals and their habitat
due to the total marine mammal take
from Spectrum’s survey activities would
have a negligible impact on all affected
marine mammal species or stocks.
Based on our evaluation of Spectrum’s
modified survey plan, we affirm that
this conclusion remains valid, and we
authorize the revised take numbers
shown in Table 17. Similarly, as
previously described in ‘‘Small
Numbers Analyses,’’ we have
determined that the take of marine
mammals incidental to Spectrum’s
specified activity would represent small
numbers of marine mammals relative to
the population sizes of the affected
species or stocks. All authorized take
numbers for Spectrum have decreased
from what we considered in that small
numbers analysis and, therefore, we
affirm that this conclusion remains
valid.
In conclusion, we affirm and restate
our findings for Spectrum:
• All previously described mitigation,
monitoring, and reporting requirements
remain the same. Based on our
evaluation of these measures, we have
determined that the required mitigation
measures provide the means of effecting
the least practicable adverse impact on
marine mammal species or stocks and
their habitat, paying particular attention
to rookeries, mating grounds, and areas
of similar significance.
• With regard to the negligible impact
analysis, we refer the reader to the
analysis presented previously. In
addition, our evaluation of the modified
survey plan shows (1) total survey line
is reduced by approximately one-third;
(2) the modified survey plan does not
include new areas not originally
considered in our assessment of the
effects of Spectrum’s specified activity;
(3) Spectrum has removed lines from
portions of the survey area, including
important habitat for marine mammals;
and (4) authorized take for all taxa has
been reduced. Therefore, based on the
analysis contained herein of the likely
effects of the specified activity on
marine mammals and their habitat, and
taking into consideration the
implementation of the required
monitoring and mitigation measures, we
find that the total marine mammal take
from Spectrum’s survey activities will
have a negligible impact on the affected
marine mammal species or stocks.
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• With regard to the small numbers
analysis, we refer the reader to the
analysis presented previously. Our
evaluation of Spectrum’s modified
survey plan results in a reduction of
authorized take for all taxa. Therefore,
based on the analysis contained herein
of Spectrum’s specified activity, the
required monitoring and mitigation
measures, and the anticipated take of
marine mammals, we find that small
numbers of marine mammals will be
taken relative to the population sizes of
the affected species or stocks.
Endangered Species Act (ESA)
Section 7 of the ESA requires Federal
agencies to insure that their actions are
not likely to jeopardize the continued
existence of endangered or threatened
species or adversely modify or destroy
their designated critical habitat. Federal
agencies must consult with NMFS for
actions that may affect species under
NMFS’s jurisdiction listed as threatened
or endangered or critical habitat
designated for such species.
At the conclusion of consultation, the
consulting agency provides an opinion
stating whether the Federal agency’s
action is likely to jeopardize the
continued existence of ESA-listed
species or destroy or adversely modify
designated critical habitat.
NMFS’s issuance of IHAs to the five
companies is subject to the
requirements of Section 7 of the ESA.
Therefore, NMFS’s Office of Protected
Resources (OPR), Permits and
Conservation Division requested
initiation of a formal consultation with
the NMFS OPR, ESA Interagency
Cooperation Division on the proposed
issuance of IHAs on June 5, 2017. The
formal consultation concluded in
November 2018 and a final Biological
Opinion (BiOp) was issued. The BiOp
found that the Permits and Conservation
Division’s proposed action of issuing
the five IHAs is not likely to jeopardize
the continued existence or recovery of
blue whales, fin whales, North Atlantic
right whales, sei whales, or sperm
whales. Furthermore, the BiOp found
that the proposed action is also not
likely to adversely affect designated
critical habitat for North Atlantic right
whales.
National Environmental Policy Act
In 2014, the BOEM produced a final
Programmatic Environmental Impact
Statement (PEIS) to evaluate the direct,
indirect, and cumulative impacts of
geological and geophysical survey
activities on the Mid- and South
Atlantic OCS, pursuant to requirements
of NEPA. These activities include
geophysical surveys in support of
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hydrocarbon exploration, as were
proposed in the MMPA applications
before NMFS. The PEIS is available at:
www.boem.gov/Atlantic-G-G-PEIS/.
NOAA, through NMFS, participated in
preparation of the PEIS as a cooperating
agency due to its legal jurisdiction and
special expertise in conservation and
management of marine mammals,
including its responsibility to authorize
incidental take of marine mammals
under the MMPA.
NEPA, Council on Environmental
Quality (CEQ) regulations, and NOAA’s
NEPA implementing procedures (NOAA
Administrative Order (NAO) 216–6A)
encourage the use of programmatic
NEPA documents and tiering to
streamline decision-making in staged
decision-making processes that progress
from programmatic analyses to sitespecific reviews. NMFS reviewed the
Final PEIS and determined that it meets
the requirements of the CEQ regulations
(40 CFR part 1500–1508) and NAO 216–
6A. NMFS further determined, after
independent review, that the Final PEIS
satisfied NMFS’s comments and
suggestions in the NEPA process. In our
Notice of Proposed IHAs, we stated our
intention to adopt BOEM’s analysis in
order to assess the impacts to the human
environment of issuance of the subject
IHAs, and that we would review all
comments submitted in response to the
notice as we completed the NEPA
process, including a final decision of
whether to adopt BOEM’s PEIS and sign
a Record of Decision related to issuance
of IHAs. Following review of public
comments received, we confirmed that
it would be appropriate to adopt
BOEM’s analysis in order to support our
assessment of the impacts to the human
environment of issuance of the subject
IHAs. Therefore, on February 23, 2018,
NMFS signed a Record of Decision for
the following purposes: (1) To adopt the
Final PEIS to support NMFS’s analysis
associated with issuance of incidental
take authorizations pursuant to sections
101(a)(5)(A) or (D) of the MMPA and the
regulations governing the taking and
importing of marine mammals (50 CFR
part 216), and (2) in accordance with 40
CFR 1505.2, to announce and explain
the basis for our decision to review and
potentially issue incidental take
authorizations under the MMPA on a
case-by-case basis, if appropriate.
Following review of public comment,
we also determined that conducting
additional NEPA review and preparing
a tiered Environmental Assessment (EA)
is appropriate to analyze environmental
impacts associated with NMFS’s
issuance of separate IHAs to five
different applicants. Through the
description and analysis of NMFS’s
E:\FR\FM\07DEN2.SGM
07DEN2
Federal Register / Vol. 83, No. 235 / Friday, December 7, 2018 / Notices
amozie on DSK3GDR082PROD with NOTICES2
activity provided in the EA as well as
the analyses incorporated by reference
from the Notice of Proposed IHAs and
BOEM’s PEIS, NMFS found that
authorizing take of marine mammals by
issuing individual IHAs to the five
applicants will not result in significant
direct, indirect, or cumulative impacts
to the human environment.
Accordingly, NMFS determined that
issuance of IHAs to the five applicants
would not significantly impact the
VerDate Sep<11>2014
18:20 Dec 06, 2018
Jkt 247001
quality of the human environment and
signed a Finding of No Significant
Impact (FONSI). NMFS’s ROD, EA, and
FONSI are available online at:
www.fisheries.noaa.gov/action/
incidental-take-authorization-oil-andgas-industry-geophysical-surveyactivity-atlantic.
Authorizations
As a result of these determinations,
NMFS has issued five separate IHAs to
the aforementioned applicant
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63381
companies for conducting the described
geophysical survey activities in the
Atlantic Ocean within the specific
geographic region, incorporating the
previously mentioned mitigation,
monitoring, and reporting requirements.
Dated: November 30, 2018.
Donna S. Wieting,
Director, Office of Protected Resources,
National Marine Fisheries Service.
[FR Doc. 2018–26460 Filed 12–6–18; 8:45 am]
BILLING CODE 3510–22–P
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Agencies
[Federal Register Volume 83, Number 235 (Friday, December 7, 2018)]
[Notices]
[Pages 63268-63381]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2018-26460]
[[Page 63267]]
Vol. 83
Friday,
No. 235
December 7, 2018
Part III
Department of Commerce
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National Oceanic and Atmospheric Administration
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Takes of Marine Mammals Incidental to Specified Activities; Taking
Marine Mammals Incidental to Geophysical Surveys in the Atlantic Ocean;
Notice
Federal Register / Vol. 83 , No. 235 / Friday, December 7, 2018 /
Notices
[[Page 63268]]
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DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
RIN 0648-XE283
Takes of Marine Mammals Incidental to Specified Activities;
Taking Marine Mammals Incidental to Geophysical Surveys in the Atlantic
Ocean
AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and
Atmospheric Administration (NOAA), Commerce.
ACTION: Notice; issuance of five incidental harassment authorizations.
-----------------------------------------------------------------------
SUMMARY: In accordance with the regulations implementing the Marine
Mammal Protection Act (MMPA) as amended, notification is hereby given
that we have issued incidental harassment authorizations (IHA) to five
separate applicants to incidentally harass marine mammals during
geophysical survey activities in the Atlantic Ocean.
DATES: These authorizations are effective for one year from the date of
effectiveness.
FOR FURTHER INFORMATION CONTACT: Ben Laws, Office of Protected
Resources, NMFS, (301) 427-8401.
SUPPLEMENTARY INFORMATION:
Availability
Electronic copies of the applications and supporting documents, as
well as a list of the references cited in this document, may be
obtained online at: www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-atlantic. In case of problems accessing these documents, please call
the contact listed above.
Background
Section 101(a)(5)(D) of the MMPA (16 U.S.C. 1361 et seq.) directs
the Secretary of Commerce (as delegated to NMFS) to allow, upon
request, the incidental, but not intentional, taking of small numbers
of marine mammals by U.S. citizens who engage in a specified activity
(other than commercial fishing) within a specific geographic region if
certain findings are made and notice of a proposed authorization is
provided to the public for review.
An authorization for incidental takings shall be granted if NMFS
finds that the taking will have a negligible impact on the species or
stock(s), will not have an unmitigable adverse impact on the
availability of the species or stock(s) for subsistence uses (where
relevant), and if the permissible methods of taking and requirements
pertaining to the mitigation, monitoring and reporting of such takings
are set forth.
NMFS has defined ``negligible impact'' in 50 CFR 216.103 as an
impact resulting from the specified activity that cannot be reasonably
expected to, and is not reasonably likely to, adversely affect the
species or stock through effects on annual rates of recruitment or
survival.
The MMPA states that the term ``take'' means to harass, hunt,
capture, or kill, or attempt to harass, hunt, capture, or kill any
marine mammal.
Except with respect to certain activities not pertinent here, the
MMPA defines ``harassment'' as any act of pursuit, torment, or
annoyance which (i) has the potential to injure a marine mammal or
marine mammal stock in the wild (Level A harassment); or (ii) has the
potential to disturb a marine mammal or marine mammal stock in the wild
by causing disruption of behavioral patterns, including, but not
limited to, migration, breathing, nursing, breeding, feeding, or
sheltering (Level B harassment).
Summary of Requests
In 2014, the Bureau of Ocean Energy Management (BOEM) produced a
Programmatic Environmental Impact Statement (PEIS) to evaluate
potential significant environmental effects of geological and
geophysical (G&G) activities on the Mid- and South Atlantic Outer
Continental Shelf (OCS), pursuant to requirements of the National
Environmental Policy Act (NEPA). BOEM's PEIS and associated Record of
Decision are available online at: www.boem.gov/Atlantic-G-G-PEIS/. G&G
activities include geophysical surveys in support of hydrocarbon
exploration, as are planned by the five IHA applicants discussed
herein.
In 2014-15, we received multiple separate requests for
authorization for take of marine mammals incidental to geophysical
surveys in support of hydrocarbon exploration in the Atlantic Ocean.
The applicants are companies that provide services, such as geophysical
data acquisition, to the oil and gas industry. Upon review of these
requests, we submitted questions, comments, and requests for additional
information to the individual applicant companies. As a result of these
interactions, the applicant companies provided revised versions of the
applications that we determined were adequate and complete. Adequate
and complete applications were received from ION GeoVentures (ION) on
June 24, 2015, Spectrum Geo Inc. (Spectrum) on July 6, 2015, and from
TGS-NOPEC Geophysical Company (TGS) on July 21, 2015.
We subsequently posted these applications for public review and
sought public input (80 FR 45195; July 29, 2015). The comments and
information received during this public review period informed
development of the proposed IHAs (82 FR 26244; June 6, 2017), and all
letters received are available online at www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-atlantic. Following conclusion of this opportunity for public
review, we received revised applications from Spectrum on September 18,
2015, and from TGS on February 10, 2016. We received additional
information from ION on February 29, 2016. We also received adequate
and complete applications from two additional applicants: WesternGeco,
LLC (Western) on February 17, 2016, and CGG on May 26, 2016. Full
details regarding these timelines were described in our Federal
Register Notice of Proposed IHAs (82 FR 26244; June 6, 2017).
On June 26, 2018, Spectrum notified NMFS of a modification to their
survey plan. Spectrum's letter and related information is available
online, as is their preceding adequate and complete application. The
descriptions and analyses contained herein were complete at the time we
received notification of the modification. Therefore, we present those
descriptions and analyses, including those related to Spectrum's
request (as detailed in their 2015 application), intact as originally
developed. However, we provide detail regarding Spectrum's modified
survey plan, our evaluation of the modification to the specified
activity, and our finding that the determinations made in regard to
Spectrum's previously proposed specified activity remain appropriate
and valid in a standalone section entitled ``Spectrum Survey Plan
Modification'' at the end of this notice.
All issued authorizations are valid for the statutory maximum of
one year. All applicants plan to conduct two-dimensional (2D) marine
seismic surveys using airgun arrays. Generally speaking, these surveys
may occur within the U.S. Exclusive Economic Zone (EEZ) (i.e., to 200
nautical miles (nmi)) from Delaware to approximately Cape Canaveral,
Florida, and corresponding with BOEM's Mid- and South Atlantic OCS
planning areas, as well as additional waters out to 350 nmi from shore.
Please see the applications for specific details of survey design. The
use of airgun arrays is expected to
[[Page 63269]]
produce underwater sound at levels that have the potential to result in
harassment of marine mammals. Multiple cetacean species with the
expected potential to be present during all or a portion of the planned
surveys are described below.
Because the specified activity, specific geographic region, and
planned dates of activity are substantially similar for the five
separate requests for authorization, we have determined it appropriate
to provide a joint notice for issuance of the five authorizations.
However, while we provide relevant information together, we consider
the potential impacts of the specified activities independently and
make determinations specific to each request for authorization, as
required by the MMPA.
Description of the Specified Activities
In this section, we provide a generalized discussion that is
broadly applicable to all five requests for authorization, with
project-specific portions indicated.
Overview
The five applicants plan to conduct deep penetration seismic
surveys using airgun arrays as an acoustic source. Seismic surveys are
one method of obtaining geophysical data used to characterize the
subsurface structure, in this case in support of hydrocarbon
exploration. The planned surveys are 2D surveys, designed to acquire
data over large areas in order to screen for potential hydrocarbon
prospectivity. To contrast, three-dimensional surveys may use similar
acoustic sources but are designed to cover smaller areas with greater
resolution (e.g., with closer survey line spacing). A deep penetration
survey uses an acoustic source suited to provide data on geological
formations that may be thousands of meters (m) beneath the seafloor, as
compared with a survey that may be intended to evaluate shallow
subsurface formations or the seafloor itself (e.g., for hazards).
An airgun is a device used to emit acoustic energy pulses into the
seafloor, and generally consists of a steel cylinder that is charged
with high-pressure air. The firing pressure of an array is typically
2,000 pounds per square inch (psi). Release of the compressed air into
the water column generates a signal that reflects (or refracts) off of
the seafloor and/or subsurface layers having acoustic impedance
contrast. When fired, a brief (~0.1 second (s)) pulse of sound is
emitted by all airguns nearly simultaneously. The airguns do not fire
during the intervening periods, with the array typically fired on a
fixed distance (or shot point) interval. This interval may vary
depending on survey objectives, but a typical interval for a 2D survey
in relatively deep water might be 25 m (approximately every 10 s,
depending on vessel speed). Vessel speed when towing gear is typically
4-5 knots (kn). The return signal is recorded by a listening device and
later analyzed with computer interpretation and mapping systems used to
depict the subsurface. In this case, towed streamers contain
hydrophones that would record the return signal.
Individual airguns are available in different volumetric sizes, and
for deep penetration seismic surveys are towed in arrays (i.e., a
certain number of airguns of varying sizes in a certain arrangement)
designed according to a given company's method of data acquisition,
seismic target, and data processing capabilities. A typical large
airgun array, as was considered in BOEM's PEIS (BOEM, 2014a), may have
a total volume of approximately 5,400 cubic inches (in\3\). The
notional array modeled by BOEM consists of 18 airguns in three
identical strings of six airguns each, with individual airguns ranging
in volume from 105-660 in\3\. Sound levels for airgun arrays are
typically modeled or measured at some distance from the source and a
nominal source level then back-calculated. Because these arrays
constitute a distributed acoustic source rather than a single point
source (i.e., the ``source'' is actually comprised of multiple sources
with some pre-determined spatial arrangement), the highest sound levels
measurable at any location in the water will be less than the nominal
source level. A common analogy is to an array of light bulbs; at
sufficient distance the array will appear to be a single point source
of light but individual sources, each with less intensity than that of
the whole, may be discerned at closer distances. In addition, the
effective source level for sound propagating in near-horizontal
directions (i.e., directions likely to impact most marine mammals in
the vicinity of an array) is likely to be substantially lower than the
nominal source level applicable to downward propagation because of the
directional nature of the sound from the airgun array. The horizontal
propagation of sound is reduced by noise cancellation effects created
when sound from neighboring airguns on the same horizontal plane
partially cancel each other out.
Survey protocols generally involve a predetermined set of survey,
or track, lines. The seismic acquisition vessel (source vessel) will
travel down a linear track for some distance until a line of data is
acquired, then turn and acquire data on a different track. In addition
to the line over which data acquisition is desired, full-power
operation may include run-in and run-out. Run-in is approximately 1
kilometer (km) of full-power source operation before starting a new
line to ensure equipment is functioning properly, and run-out is
additional full-power operation beyond the conclusion of a trackline
(typically half the distance of the acquisition streamer behind the
source vessel) to ensure that all data along the trackline are
collected by the streamer. Line turns typically require two to three
hours due to the long, trailing streamers (approximately 10 km).
Spacing and length of tracks vary by survey. Survey operations often
involve the source vessel, supported by a chase vessel. Chase vessels
typically support the source vessel by protecting the hydrophone
streamer from damage (e.g., from other vessels) and otherwise lending
logistical support (e.g., returning to port for fuel, supplies, or any
necessary personnel transfers). Chase vessels do not deploy acoustic
sources for data acquisition purposes; the only potential effects of
the chase vessels are those associated with normal vessel operations.
Dates and Duration
All issued IHAs are valid for the statutory maximum of one year
from the date of effectiveness. The IHAs are effective upon written
notification from the applicant to NMFS, but not beginning later than
one year from the date of issuance or extending beyond two years from
the date of issuance. However, the expected temporal extent of survey
activity varies by company and may be subject to unpredictability due
to inclement weather days, equipment maintenance and/or repair, transit
to and from ports to survey locations, and other contingencies.
Spectrum originally planned a 6-month data acquisition program
(February through July), consisting of an expected 165 days of seismic
operations. This plan has been modified and now consists of an
estimated 108 days of operations. Please see ``Spectrum Survey Plan
Modification'' for further information. TGS plans a full year data
acquisition program, with an estimated 308 days of seismic operations.
ION plans a six-month data acquisition program (July through December),
with an estimated 70 days of seismic data collection. Western plans a
full year data acquisition program, with an estimated 208 days of
seismic operations. CGG plans a six-month data acquisition program
(July through
[[Page 63270]]
December), with an estimated 155 days of seismic operations. Seismic
operations typically occur 24 hours per day.
Specific Geographic Region
The planned survey activities would occur off the Atlantic coast of
the United States, within BOEM's Mid-Atlantic and South Atlantic OCS
planning areas (i.e., from Delaware to Cape Canaveral, FL), and out to
350 nmi (648 km) (see Figure 1, reproduced from BOEM, 2014a). The
seaward limit of the region is based on the maximum constraint line for
the extended continental shelf (ECS) under the United Nations
Convention on the Law of the Sea. Until such time as an ECS is
established by the United States, the region between the U.S. EEZ
boundary and the ECS maximum constraint line (i.e., 200-350 nmi from
shore) is part of the global commons, and BOEM determined it
appropriate to include this area within the area of interest for
geophysical survey activity.
The specific survey areas differ within this region; please see
maps provided in the individual applications (Spectrum: Figure 1;
Western: Figures 1-1 to 1-4; TGS: Figures 1-1 to 1-4; ION: Figure 1;
CGG: Figure 3) (however, please see ``Spectrum Survey Plan
Modification'' for further information). The specific geographic region
has not changed compared with what was described in our Notice of
Proposed IHAs (82 FR 26244; June 6, 2017), nor has substantive new
information regarding the region become available. Therefore, we do not
reprint that discussion here; for additional detail regarding the
specific geographic region, please see our Notice of Proposed IHAs.
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BILLING CODE 3510-22-P
Detailed Description of Activities
Survey descriptions, as summarized from specific applications, are
provided here. Please see Table 1 for a summary of airgun array
characteristics. With the exception of Spectrum, the planned surveys
have not changed from those described in our Notice of Proposed IHAs
(82 FR 26244; June 6, 2017) Please see ``Spectrum Survey Plan
Modification'' for further information. For full detail, please see the
individual IHA applications and our Notice of Proposed IHAs. Note that
all applicants expect there to be limited additional operations
associated with equipment testing, startup, line changes, and repeat
coverage of any areas where initial data quality is sub-standard.
Therefore, there
[[Page 63272]]
could be some small amount of use of the acoustic source not accounted
for in the total estimated line-km for each survey; however, this
activity is difficult to quantify in advance and would represent an
insignificant increase in effort.
ION--ION's survey is planned to occur from Delaware to northern
Florida (~38.5[deg] N to ~27.9[deg] N) (see Figure 1 of ION's
application), and consists of ~13,062 km of survey line. The acoustic
source planned for deployment is a 36-airgun array with a total volume
of 6,420 in\3\. The array would consist of airguns ranging in volume
from 40 in\3\ to 380 in\3\. The airguns would be configured as four
identical linear arrays or ``strings'' (see Figure 3 of ION's
application). The four airgun strings would be towed at 10-m depth, and
would fire every 50 m or 20-24 s, depending on exact vessel speed. ION
provided modeling results for their array, including notional source
signatures, 1/3-octave band source levels as a function of azimuth
angle, and received sound levels as a function of distance and
direction at 16 representative sites in the survey area. For more
detail, please see Figures 4-6 and Appendix A of ION's application.
Spectrum--Spectrum's survey was originally planned to occur from
Delaware to northern Florida (see Figure 1 of Spectrum's application),
consisting of ~21,635 km of survey line. This plan has been modified
and now consists of ~13,766 km of operations. Please see ``Spectrum
Survey Plan Modification'' for further information). The acoustic
source planned for deployment is a 32-airgun array with a total volume
of 4,920 in\3\. The array would consist of airguns ranging in volume
from 50 in\3\ to 250 in\3\. The airguns would be configured as four
subarrays, each with eight to ten airguns (see Figure 2 in Appendix A
of Spectrum's application). The four airgun strings would be towed at 6
to 10-m depth, and would fire every 25 m or 10 s, depending on exact
vessel speed. Spectrum provided modeling results for their array,
including notional source signatures, 1/3-octave band source levels as
a function of azimuth angle, and received sound levels as a function of
distance and direction at 16 representative sites in the survey area.
For more detail, please see Appendix A of Spectrum's application.
As stated above, Spectrum notified NMFS on June 26, 2018, of a
modification to their survey plan. Please see ``Spectrum Survey Plan
Modification'' for further information.
TGS--TGS's survey is planned to occur from Delaware to northern
Florida (see Figure 1-1 of TGS's application), and consists of ~58,300
km of survey line. The survey plan consists of two contiguous survey
grids with differently spaced lines (see Figures 1-1 to 1-4 of TGS's
application), and would involve use of two source vessels operating
independently of one another at a minimum of 100 km separation
distance. The acoustic sources planned for deployment are 40-airgun
arrays with a total volume of 4,808 in\3\. The array would consist of
airguns ranging in volume from 22 in\3\ to 250 in\3\. The airguns would
be configured as four identical strings (see Figure 3 in Appendix B of
TGS's application). The four airgun strings would be towed at 7-m
depth, and would fire every 25 m or 10 s, depending on exact vessel
speed. More detail regarding TGS's acoustic source and modeling related
to TGS's application is provided in Appendix B of TGS's application.
Western--Western's survey is planned to occur from Maryland to
northern Florida (see Figure 1-1 of Western's application), and
consists of ~27,330 km of survey line. The survey plan consists of a
survey grid with differently spaced lines (see Figures 1-1 to 1-4 of
Western's application). The acoustic source planned for deployment is a
24-airgun array with a total volume of 5,085 in\3\. The airguns would
be configured as three identical strings. The three airgun strings
would be towed at 10-m depth, and would fire every 37.5 m
(approximately every 16 s, depending on vessel speed). More detail
regarding Western's acoustic source and modeling related to Western's
application is provided in Appendix B of Western's application.
CGG--CGG's survey is planned to occur from Virginia to Georgia (see
Figure 3 of CGG's application), and consists of ~28,670 km of survey
line. The acoustic source planned for deployment is a 36-airgun array
with a total volume of 5,400 in\3\. The array would consist of airguns
ranging in volume from 40 in\3\ to 380 in\3\. The airguns would be
configured as four identical strings (see Figure 2 of CGG's
application). The four airgun strings would be towed at 7-m depth, and
would fire every 25 m or 10 s, depending on exact vessel speed. More
detail regarding CGG's acoustic source and modeling related to CGG's
application is provided in CGG's application.
Table 1--Survey and Airgun Array Characteristics
--------------------------------------------------------------------------------------------------------------------------------------------------------
Total Total Nominal source output (downward) \1\ Shot
Company planned volume Number of Number of --------------------------------------- interval Tow depth
survey km (in\3\) guns strings 0-pk pk-pk rms (m) (m)
--------------------------------------------------------------------------------------------------------------------------------------------------------
ION................................ 13,062 6,420 36 4 257 263 \4\ 247 50 10
Spectrum........................... 13,766 4,920 32 4 266 272 243 25 6-10
TGS................................ 58,300 4,808 40 4 255 (\3\) 240 25 7
Western............................ 27,330 5,085 24 3 (\3\) 262 235 37.5 10
CGG................................ 28,670 5,400 36 4 (\3\) 259 3 4 243 25 7
BOEM \2\........................... n/a 5,400 18 3 247 (\3\) 233 n/a 6.5
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ See ``Description of Active Acoustic Sound Sources,'' later in this document, for discussion of these concepts.
\2\ Notional array characteristics modeled and source characterization outputs from BOEM's PEIS (2014a) provided for comparison.
\3\ Values not given; however, SPL (pk-pk) is usually considered to be approximately 6 dB higher than SPL (0-pk) (Greene, 1997).
\4\ Value decreased from modeled 0-pk value by minimum 10 dB (Greene, 1997).
Comments and Responses
We published a Notice of Proposed IHAs in the Federal Register on
June 6, 2017 (82 FR 26244), beginning a 30-day comment period. In that
notice, we requested public input on the requests for authorization
described therein, our analyses, the proposed authorizations, and any
other aspect of the Notice of Proposed IHAs for the five separate
specified geophysical survey activities, and requested that interested
persons submit relevant information, suggestions, and comments. We
further specified that, in accordance with the requirements of the
MMPA, we would only consider comments that were relevant to marine
mammal species that occur in U.S. waters of the Mid- and South Atlantic
and the potential effects of the specified geophysical survey
activities on those species and their habitat. We also noted that
comments
[[Page 63273]]
indicating general support for or opposition to hydrocarbon exploration
or any comments relating to hydrocarbon development (e.g., leasing,
drilling) were not relevant to the proposed actions and would not be
considered. We requested that comments indicate whether they were
general to all of the proposed authorizations or specific to one or
more of the five separate proposed authorizations, and that comments
should be supported by data or literature citations as appropriate.
Following requests to extend the public comment period, we determined
it appropriate to do so by an additional 15 days (82 FR 31048; July 5,
2017). Including the 15-day extension, the public comment period
concluded on July 21, 2017. Comments received after the close of the
comment period were not considered.
During the 45-day comment period, we received 117,294 total comment
letters. Of this total, we determined that approximately 3,196 comment
letters represented unique submissions, including 73 letters from
various organizations or individuals acting in an official capacity
(e.g., non-governmental organizations, representatives and members of
the oil and gas industry, state and local government, members of
Congress, members of academia) and 3,103 unique submissions from
private citizens. We note that the 73 letters represent approximately
330 organizations or individuals, as many letters included multiple co-
signers. The remaining approximately 114,118 comment letters followed
one of 20 different generic template formats, in which respondents
provided comments that were identical or substantively the same. We
consider each of the 20 different templates to represent a single
unique submission that is included in the value cited above (3,196).
Separately, we received 15 petitions, with a total of 99,423
signatures. Of these, one petition (595 signatures) expressed support
for issuance of the proposed IHAs, while the remainder expressed
opposition to issuance of the proposed IHAs or, more generally, to oil
and gas exploration and/or development in the U.S. Atlantic Ocean.
NMFS has reviewed all public comments received on the proposed
issuance of the five IHAs. All relevant comments and our responses are
described below. Comments indicating general support for or opposition
to hydrocarbon exploration but not containing relevant recommendations
or information are not addressed here. Similarly, any comments relating
to hydrocarbon development (e.g., leasing, drilling)--including
numerous comments received that expressed concern regarding the risks
of oil spills or of potential future industrialization on the U.S.
Atlantic coast--are not relevant to the proposed actions and therefore
were not considered and are not addressed here. We also provide no
response to specific comments that addressed species or statutes not
relevant to our proposed actions under section 101(a)(5)(D) of the MMPA
(e.g., comments related to sea turtles), nor do we respond to comments
more appropriately directed at BOEM pursuant to their authority under
the Outer Continental Shelf Lands Act (OCSLA) to permit the planned
activities. For those comments germane to the proposed IHAs, we outline
our comment responses by major categories. Recurring comments are noted
below as having been submitted by ``several'' or ``many'' commenters to
avoid repetition. The 73 letters from various organizations or
individuals acting in an official capacity, and representatives of each
of the 20 form letter templates, are available online at:
www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-atlantic. Remaining comments
are part of our administrative record for these actions but are not
available online.
General Comments
A large majority of commenters, including all of those following
one of the 20 templates, expressed general opposition towards
geophysical airgun surveys in the U.S. Atlantic Ocean. We reiterate
here that NMFS's proposed actions concern only the authorization of
marine mammal take incidental to the planned surveys--jurisdiction
concerning decisions to allow the surveys rests solely with BOEM,
pursuant to their authority under the OCSLA. Further, NMFS does not
have discretion regarding issuance of requested incidental take
authorizations pursuant to the MMPA, assuming (1) the total taking
associated with a specified activity will have a negligible impact on
the affected species or stock(s); (2) the total taking associated with
a specified activity will not have an unmitigable adverse impact on the
availability of the species or stock(s) for subsistence uses (not
relevant here); (3) the total taking associated with a specified
activity is small numbers of marine mammals of any species or stock;
and (4) appropriate mitigation, monitoring, and reporting of such
takings are set forth, including mitigation measures sufficient to meet
the standard of least practicable adverse impact on the affected
species or stocks. A large volume of the comments received request that
NMFS not issue any of the IHAs and/or express disdain for NMFS's
proposal to issue the requested IHAs, but without providing information
relevant to NMFS's decisions. These comments appear to indicate a lack
of understanding of the MMPA's requirement that NMFS shall issue
requested authorizations when the above listed conditions are met;
therefore, these comments were not considered.
In general, commenters described the close linkages between their
local and state economies to a healthy ocean, contending that the
planned surveys could have substantial impacts on, for example,
commercial and recreational fishing, wildlife viewing, outdoor
recreation, and businesses dependent on these activities. Commenters
suggested that NMFS should undertake analyses unrelated to the proposed
actions (i.e., issuance of requested IHAs), such as a cost-benefit
analysis of hydrocarbon exploration and development compared to the
economic benefits of coastal tourism and healthy fisheries. Many
commenters also noted that over 120 municipalities and cities and 1,200
elected officials on the Atlantic coast have passed resolutions or
otherwise formally opposed hydrocarbon exploration and/or development
in the region. We also received comments expressing general opposition
to oil and gas exploration activity from the Business Alliance for
Protecting the Atlantic Coast, which stated that the comments were
submitted on behalf of 41,000 businesses and 500,000 commercial fishing
families. While NMFS recognizes the overwhelming opposition expressed
by the public to oil and gas exploration and/or development in the U.S.
Atlantic Ocean that it has received, we remain appropriately focused on
consideration of the best available scientific information in support
of our analyses pursuant to the MMPA, specific to the five IHAs
considered herein.
Multiple commenters focused on specific, rather than general,
issues that are not germane to our consideration of requested action
under the MMPA. For example, the Northwest Atlantic Marine Alliance
(NAMA) and other groups provided comments related to potential impacts
on commercial fisheries, and the New Jersey Council of Diving Clubs
expressed concern regarding potential impacts of the planned surveys on
recreational divers. Recommendations were provided concerning
mitigating potential impacts. We reiterate that NMFS's proposed
action--the issuance
[[Page 63274]]
of IHAs authorizing incidental take of marine mammals--necessarily
results in impacts only to marine mammals and marine mammal habitat.
Effects of the surveys more broadly are the purview of BOEM, which has
jurisdiction under OCSLA for permitting the actual surveys, as opposed
to authorizing take of marine mammals incidental to a permitted survey.
Therefore, we do not address comments such as these.
Multiple groups stated that NMFS should consider impacts and
protection for other species in the action area, such as Atlantic
sturgeon, other fish species, invertebrates, plankton, and sea turtles.
Some of these comments specifically referenced the importance of the
area offshore Cape Hatteras as home to a diverse assemblage of non-
marine mammal species, including sharks, turtles, seabirds, and other
fish species. The NAMA provided comments relating to Essential Fish
Habitat (EFH) (as designated pursuant to the Magnuson Stevens Fishery
Conservation and Management Act (MSA), as amended by the Sustainable
Fisheries Act of 1996 (Pub. L. 104-267)), including concerns regarding
effects to EFH resulting from the planned surveys. Because NMFS's
proposed action is limited to the authorization of marine mammal take
incidental to the planned surveys, effects of the surveys on aspects of
the marine environment other than marine mammals and their habitat are
not relevant to NMFS's analyses under the MMPA. Pursuant to guidance
from NMFS's Office of Habitat Conservation concerning EFH and MMPA
incidental take authorizations, we have determined that the issuance of
these IHAs will not result in adverse impacts to EFH, and further, that
issuance of these IHAs does not require separate consultation per
section 305(B)(2) of the MSA. We do not further address potential
impacts to EFH.
The MMPA does require that we evaluate potential effects to marine
mammal habitat, which includes prey species (e.g., zooplankton, fish,
squid). However, consideration of potential effects to taxa other than
marine mammals and their prey, or consideration of effects to potential
prey species in a context other than the import of such effects on
marine mammals, is not relevant to our action under the MMPA. We have
appropriately considered effects to marine mammal habitat. Separately,
BOEM evaluated effects to all relevant aspects of the human environment
(including marine mammals and other taxa) through the analysis
presented in their PEIS (available online at: www.boem.gov/Atlantic-G-G-PEIS/), and effects to all potentially affected species that are
listed under the Endangered Species Act (ESA) and any critical habitat
designated for those species were addressed through consultation
between BOEM and NMFS pursuant to section 7 of the ESA. That Biological
Opinion, which evaluated both BOEM's (issuing permits for the five
surveys) and NMFS's (issuing IHAs associated with the five permitted
surveys) proposed actions, is available online at:
www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-atlantic. We do not further
address taxa other than marine mammals and marine mammal prey.
Marine Mammal Impacts
Comment: Many commenters expressed concern regarding the perceived
lack of information regarding the affected marine mammal stocks and the
impacts of the surveys on marine mammal individuals and populations and
their habitat (direct and indirect; short- and long-term).
Response: NMFS acknowledges that, while there is a growing body of
literature on the affected marine mammal stocks and regarding the
impacts of noise on individual marine mammals, data gaps do remain,
particularly with regard to potential population-level impacts and
cumulative impacts. However, NMFS must use the best available
scientific information in analyses supporting its determinations
pursuant to the MMPA, and has done so here. While NMFS does not take
lightly the potential effects of surveys on marine mammal populations,
these surveys, with the robust suite of required mitigation and
monitoring, are expected to have a negligible impact on the affected
species and stocks.
Comment: Many commenters expressed general concern regarding
impacts to both individual marine mammals and potential population-
level harm, including impacts to important behaviors and chronic stress
stemming from acoustic disturbance. More specifically, this included:
Potential displacement from preferred feeding, breeding, and migratory
habitats, which could lead to long-term and large-scale habitat
avoidance or abandonment; impacts to mating, vocalizing, and other key
marine mammal behaviors; communication interference between cow-calf
pairs, which could lead to stranding increases and juvenile deaths;
hearing loss hindering recruitment and marine mammals' ability to
locate mates and find food.
Response: NMFS has carefully reviewed the best available scientific
information in assessing impacts to marine mammals, and recognizes that
the surveys have the potential to impact marine mammals through
threshold shifts, behavioral effects, stress responses, and auditory
masking. However, NMFS has determined that the nature of such
potentially transitory exposure--any given location will be exposed to
survey noise only relatively briefly and infrequently--means that the
potential significance of the authorized taking, including potential
long-term avoidance, is limited. NMFS has also prescribed a robust
suite of mitigation measures, such as time-area restrictions and
extended distance shutdowns for certain species, that are expected to
further reduce the duration and intensity of acoustic exposure, while
limiting the potential severity of any possible behavioral disruption.
Comment: Many commenters described impacts to ``millions of marine
mammals,'' expressing concern that NMFS would allow such a level of
impacts, or stating concern that NMFS would allow killing of marine
mammals. Similarly, many commenters refer to taking or killing
``138,000 marine mammals.''
Response: Many of these comments were written with reference to the
acoustic exposure analysis provided in BOEM's PEIS, which is not
directly related to the specific surveys that are the subject of NMFS's
analysis. In fact, the more specific figure commonly cited (i.e.,
138,000) represents the number of incidents of Level A harassment
estimated by BOEM in their analysis using now-outdated guidance (i.e.,
180-dB root mean square (rms) with no consideration of frequency
sensitivity) that the best available science indicates does not reflect
when Level A harassment should be expected to occur. Certain non-
governmental organizations have incorrectly suggested the information
represents animals killed. In addition, BOEM's programmatic analysis
was based on a vastly greater amount of survey activity occurring per
year over a period of nine years, versus the five surveys considered
herein. Regardless, NMFS cannot issue the authorizations unless the
total taking expected to occur as a result of each specified activity
is determined to result in a negligible impact to the affected species
or stocks. The best available science indicates that Level B
harassment, or disruption of behavioral patterns, is likely to occur,
and that a limited amount of auditory injury, or permanent threshold
shift (PTS) (Level A harassment) may occur for a few
[[Page 63275]]
species. No mortality is expected to occur as a result of the planned
surveys, and there is no scientific evidence indicating that any marine
mammal could experience mortality as a direct result of noise from
geophysical survey activity. Authorization of mortality may not occur
via IHAs, and such authorization was neither requested nor proposed.
Finally, we emphasize that an estimate of take numbers alone is not
sufficient to assess impacts to a marine mammal population. Take
numbers must be viewed contextually with other factors, as explained in
the ``Negligible Impact Analyses and Determinations'' section of this
Notice.
Comment: Several commenters referenced studies showing that noise
from airgun surveys can travel great distances underwater, leading to
concern that the surveys would impact marine mammals throughout the
specific geographic region at all times. Some commenters then suggested
that this would result in there being no available habitat for
displaced animals to escape to.
Response: NMFS acknowledges that relatively loud, low-frequency
noise (as is produced by airgun arrays) has the potential to propagate
across large distances. However, propagation and received sound levels
are highly variable based on many biological and environmental factors.
For example, while one commonly cited study (Nieukirk et al., 2012)
described detection of airgun sounds almost 4,000 km from the acoustic
source, the sensors were located within the deep sound channel (SOFAR),
where low-frequency signals may travel great distances due to the
advantageous propagation environment. While sounds within this channel
are unlikely to be heard by most marine mammals due to the depth of the
SOFAR channel--which is dependent primarily on temperature and water
pressure and therefore variable with latitude--it is arguable whether
sounds that travel such distances may be heard by whales as a result of
refraction to shallower depths (Nieukirk et al., 2012; McDonald et al.,
1995). Regardless, while the extreme propagation distances cited in
some comments may not be realistic in terms of effects on mysticetes,
we acknowledge that contraction of effective communication space for
whales that vocalize and hear at frequencies overlapping those emitted
by airgun arrays can occur at distances on the order of tens to
hundreds of kilometers. However, attenuation to levels below the
behavioral harassment criterion (i.e., 160 dB rms) will likely always
occur over much shorter distances and, therefore, we do not agree with
the contention that essentially the entire specific geographic region
would be ensonified to a degree that marine mammals would find it
unsuitable habitat. Rather, it is likely that displacement would occur
within a much smaller region in the vicinity of the acoustic source
(e.g., within 5-10 km of the source, depending on season and location).
Overall, the specific geographic region and marine mammal use of the
area is sufficiently large that, although displacement may occur, the
region offers enough habitat for marine mammals to seek temporary
viable habitat elsewhere, if necessary. Many of the affected species
occupy a wide portion of the region, and it is expected that
individuals of these species can reasonably find temporary foraging
grounds or other suitable habitat areas consistent with their natural
use of the region. Further, although the planned surveys would cover
large portions of the U.S. Mid- and South Atlantic, they will only be
transitory in any given area. Therefore, NMFS does not expect
displacement to occur frequently or for long durations. Importantly,
for species that show high site fidelity to a particular area (e.g.,
pilot whales around Cape Hatteras) or to bathymetric features (e.g.,
sperm whales and beaked whales), NMFS has required additional time-area
restrictions to reasonably minimize these impacts.
Comment: The Bald Head Island Association commented that many
bottlenose dolphin populations are depleted, and risks from the surveys
are too great.
Response: NMFS acknowledges that coastal bottlenose dolphin stocks
are depleted under the MMPA, and we described the 2013-2015 Unusual
Mortality Event affecting these stocks in our Notice of Proposed IHAs.
NMFS is requiring a year-round closure to all survey activity out to 30
km offshore, including a 20-km distance beyond which encountered
dolphins would generally be expected to be of the offshore stock and a
10-km buffer distance that is expected to encompass all received sound
levels exceeding the 160-dB rms Level B harassment criterion. In
consideration of this mitigation requirement, NMFS believes that
impacts to coastal bottlenose dolphins will be minimal.
Comment: The New York State Department of Environmental
Conservation expressed concern about impacts from the surveys to
animals in the New York Bight, noting that even though the surveys
would not be occurring in the vicinity of New York Bight many of the
same animals that use the New York Bight for certain life history
strategies would also be found in certain times of year in the specific
geographic region.
Response: Although unrelated to our analyses and necessary findings
pursuant to the MMPA, we note that in requesting the opportunity to
conduct review of the proposed surveys pursuant to the Coastal Zone
Management Act, New York did not demonstrate that the surveys would
have reasonably foreseeable effects on New York's coastal uses or
resources. Therefore, New York's request was denied. However, we
acknowledge that some of the same animals that may occur in the New
York Bight could also occur at other times of year within the survey
region and, therefore, be affected by the specified activities.
However, as detailed elsewhere in this document, we have found for each
specified activity and each potentially affected species or stock that
the taking would have a negligible impact.
Comment: The Natural Resources Defense Council (NRDC) submitted
comments on behalf of itself and over thirty other organizations,
including the Center for Biological Diversity, Defenders of Wildlife,
Earthjustice, The Humane Society of the United States, Sierra Club, et
al. Hereafter, we refer to this collective letter as ``NRDC.'' NRDC and
other commenters assert that the surveys will drive marine mammals into
shipping lanes, thereby increasing their risk of ship strike.
Response: As an initial matter, we address overall themes in NRDC's
85-page comment letter. In addition to mischaracterizing the
literature, likely impacts to marine mammals, and NMFS's analyses in
multiple places--which we attempt to correct throughout our responses--
the letter repeatedly makes use of undefended or off-point assertions
(e.g., that NMFS's findings are ``arbitrary and capricious'' and ``non-
conservative''). While we have attempted to clarify and correct
individual mischaracterizations in our specific responses to comments,
we broadly address the issue here. NRDC's 16 assertions that NMFS's
analyses and/or conclusions are ``arbitrary and capricious'' or just
``arbitrary'' are unfounded. Similarly, NRDC claims that NMFS's
approaches or decisions are ``non-conservative,'' or should be more
``conservative,'' at least 15 times, with no indication of what
standard they are seeking to attain. While NRDC may disagree with the
issuance of the IHAs or the underlying activities themselves, we
believe the administrative record for these IHAs amply demonstrates
that NMFS used the best available science
[[Page 63276]]
during our administrative process to inform our analyses and satisfy
the standards under section 101(a)(5)(D).
With regard to this specific comment, the surveys are largely not
occurring in or near any shipping lanes, as they will occur a minimum
of 30 km offshore. NMFS is not aware of any scientific information
suggesting that the surveys would drive marine mammals into shipping
lanes, and disagrees that this would be a reasonably anticipated effect
of the specified activities.
Comment: Comments submitted jointly by Oceana and the International
Fund for Animal Welfare (hereafter, ``Oceana'') and, separately, by Sea
Shepherd Legal discuss particular concerns regarding potential impacts
to large whales. The comments cite studies showing modified singing
behavior and habitat avoidance among fin whales in response to airguns;
that sperm whales in the Gulf of Mexico have shown decreased buzz rates
around airguns; that singing among humpback whales declined in response
to airgun noise; etc.
Response: NMFS reviewed all cited studies in making its
determinations for both the proposed and final IHAs, and agrees that
there are multiple studies documenting changes in behavior and/or
communication amongst large whales in response to airgun noise,
sometimes at significant distance. Changes in vocalization associated
with exposure to airgun surveys within migratory and non-migratory
contexts have been observed (e.g., Castellote et al., 2012; Blackwell
et al., 2013; Cerchio et al., 2014). The potential for anthropogenic
sound to have impacts over large spatial scales is not surprising for
species with large communication spaces, like mysticetes (e.g., Clark
et al., 2009); however, not every change in a vocalization would
necessarily rise to the level of a take, much less have meaningful
consequences to the individual or for the affected population. As noted
previously, the planned surveys are expected to be transient and would
not result in any sustained impacts to such behaviors for baleen
whales. We also acknowledge that exposure to noise from airguns may
impact sperm whale foraging behavior (Miller et al., 2009). However,
our required mitigation--including time-area restrictions designed to
protect certain habitat expected to be of importance for foraging sperm
whales, in addition to standard shutdown requirements expected to
minimize the severity and duration of any disturbance--when considered
in context of the transient nature of the impacts possible for these
surveys lead us to conclude that effects to large whales will be no
greater than a negligible impact and will be mitigated to the level of
least practicable adverse impact.
Comment: Several industry commenters stated, in summary, that there
is no scientific evidence that geophysical survey activities have
caused adverse consequences to marine mammal stocks or populations, and
that there are no known instances of injury to individual marine
mammals as a result of such surveys, stating that similar surveys have
been occurring for years without significant impacts. One stated that
surveys have been ongoing in the Gulf of Mexico for years and have not
resulted in any negative impacts to marine mammals, including reducing
fitness in individuals or populations. Referring to other regions, the
commenters stated that bowhead whale numbers have increased in the
Arctic despite survey activity. CGG noted that there is no ``empirical
evidence'' of surveys causing injury or mortality to marine mammals,
and that previous surveys resulted in less take than authorized.
Another group added that BOEM has spent $50 million on protected
species and noise research over four decades with no evidence of
adverse effects.
Response: Disruption of behavioral patterns (i.e., Level B
harassment) has been documented numerous times for marine mammals in
the presence of airguns (in the form of avoidance of areas, notable
changes in vocalization or movement patterns, or other shifts in
important behaviors; see ``Potential Effects of the Specified Activity
on Marine Mammals and Their Habitat''). Further, lack of evidence for a
proposition does not prove it is false. In this case, there is growing
scientific evidence demonstrating the connections between sub-lethal
effects, such as behavioral disturbance, and population-level effects
on marine mammals (e.g., Lusseau and Bedjer, 2007; New et al., 2014).
Disruptions of important behaviors, in certain contexts and scales,
have been shown to have energetic effects that can translate to reduced
survivorship or reproductive rates of individuals (e.g., feeding is
interrupted, so growth, survivorship, or ability to bring young to term
is compromised), which in turn can adversely affect populations
depending on their health, abundance, and growth trends.
Based on the available evidence, a responsible analysis of
potential impacts of airgun noise on marine mammal individuals and
populations cannot assume that such effects cannot occur. In reality,
conclusive statements regarding population-level consequences of
acoustic stressors cannot be made due to insufficient investigation, as
such studies are exceedingly difficult to carry out and no appropriate
study and reference populations have yet been established. For example,
a recent report from the National Academy of Sciences noted that, while
a commonly-cited statement from the National Research Council (``[n]o
scientific studies have conclusively demonstrated a link between
exposure to sound and adverse effects on a marine mammal population'')
remains true, it is largely because such impacts are very difficult to
demonstrate (NRC, 2005; NAS, 2017). Population[hyphen]level effects are
inherently difficult to assess because of high variability, migrations,
and multiple factors affecting the populations. However, NMFS has
carefully considered the available evidence in determining the most
appropriate suite of mitigation measures and in making the necessary
determinations (see ``Negligible Impact Analyses and Determinations'').
Comment: NRDC states that NMFS must consider that behavioral
disturbance can amount to Level A harassment, or to serious injury or
mortality, if it interferes with essential life functions through
secondary effects, stating that displacement from migration paths can
result in heightened risk of ship strike or predation, especially for
right whales. In a similar vein, Oceana expressed concern about the
presence of additional ships in the Atlantic, risking serious injury to
marine mammals from ship strike or entanglement. Relatedly, NRDC noted
that NMFS's conclusion that ship strikes will not occur indicates an
assumption that required ship-strike avoidance procedures will be
effective. NRDC disagrees that the ship-strike avoidance measures will
be effective.
Response: NMFS acknowledges that sufficient disruption of
behavioral patterns could theoretically, likely in connection with
other stressors, result in a reduction in fitness and ultimately injury
or mortality. However, such an outcome could likely result only from
repeated disruption of important behaviors at critical junctures, or
sustained displacement from important habitat with no associated
compensatory ability. No such outcome is expected as a result of these
surveys, which will be transient in any given area within the large
overall region, and which avoid some of the most important habitat.
Effects such as those suggested by NRDC would not be expected for
[[Page 63277]]
right whales, as the surveys are required to avoid migratory pathways
(80 km from coast), or achieve comparable protection provided through
implementation of a NMFS-approved mitigation and monitoring plan at
distances between 47-80 km offshore (see ``Mitigation'' for more
information).
Although the primary stressor to marine mammals from the specified
activities is acoustic exposure to the sound source, NMFS takes
seriously the risk of vessel strike and has prescribed measures
sufficient to avoid the potential for ship strike to the extent
practicable. NMFS has required these measures despite a very low
likelihood of vessel strike; vessels associated with the surveys will
add a discountable amount of vessel traffic to the specific geographic
region (i.e., each survey will operate with roughly 2-3 vessels) and,
furthermore, vessels towing survey gear travel at very slow speeds
(i.e., roughly 4-5 kn).
NMFS's required vessel strike avoidance protocol is expected to
further minimize any potential interactions between marine mammals and
survey vessels. Please see ``Vessel Strike Avoidance'' for a full
description of requirements, which include: Vessels must maintain a 10
kn speed restriction when in North Atlantic right whale critical
habitat, Seasonal Management Areas, or Dynamic Management Areas; vessel
operators and crews must maintain a vigilant watch for all marine
mammals and must take necessary actions to avoid striking a marine
mammal; vessels must reduce speeds to 10 kn or less when mother/calf
pairs, pods, or large assemblages of cetaceans are observed near a
vessel; and vessels must maintain minimum separation distances.
Comment: NRDC stated that NMFS did not properly consider potential
impacts of masking to marine mammals. For example, NRDC notes that NMFS
addresses masking in the general consequences discussion of its
negligible impact analysis, but disagrees with NMFS's conclusion that
consequences are appropriately categorized as ``medium'' rather than
``high'' for mysticetes, citing the distances at which vocal
modifications to distant sounds have been detected in low-frequency
cetaceans and newly-described low-level communication calls between
humpback whales and their calves, which they suggest have dire
implications for right whales. NRDC also states that NMFS incorrectly
thinks masking is co-extensive with the modeled 160-dB rms behavioral
harassment zones, and suggests that NMFS should take a modeling
approach to better assess potential masking. Relatedly, another
commenter stated a belief that NMFS assumes that there is no potential
for masking during the interpulse interval, when in fact there is noise
during that period due to multipath arrivals.
Response: NMFS disagrees that the potential impacts of masking were
not properly considered. NMFS acknowledges our understanding of the
literature NRDC cites regarding the greater sensitivity of low-
frequency cetaceans to airgun survey noise via the designation of these
effects as ``medium,'' but fundamentally, the masking effects to any
one individual whale from one survey operating far offshore are
expected to be minimal. Masking is referred to as a chronic effect
because one of the key harmful components of masking is its duration--
the fact that an animal would have reduced ability to hear or interpret
critical cues becomes much more likely to cause a problem the longer it
is occurring. Also, inherent in the concept of masking is the fact that
the potential for the effect is only present during the times that the
animal and the source are in close enough proximity for the effect to
occur (and further this time period would need to coincide with a time
that the animal was utilizing sounds at the masked frequency) and, as
our analysis (both quantitative and qualitative components) indicates,
because of the relative movement of whales and vessels, we do not
expect these exposures with the potential for masking to be of a long
duration within a given day. Further, because of the relatively low
density of mysticetes, the time-area restrictions, and large area over
which the vessels travel, we do not expect any individual whales to be
exposed to potentially masking levels from these surveys more than a
few days in a year.
NMFS recognizes that masking may occur beyond the 160-dB zone and,
further, that the primary concern is when numerous sources, many of
which may be at distances beyond their 160-dB isopleth, contribute to
higher background noise levels over extended time periods and
significant portions of an individual's acoustic habitat. However, as
noted above, any masking effects of these single surveys operating far
offshore (with no expectation that any of the five would be in close
enough proximity to one another to contemporaneously expose animals to
noise from multiple source vessels) are expected to be limited and
brief, if present. Further, we recognize the presence of multipath
arrivals, especially the farther the receiver is from the ship, but
given the reduced received levels at distance, combined with the short
duration of potential masking and the lower likelihood of extensive
additional contributors to background noise this far offshore and
within these short exposure periods, we believe that the incremental
addition of the seismic vessel is unlikely to result in more than minor
and short-term masking effects, likely occurring to some small number
of the same individuals captured in the estimate of behavioral
harassment.
In regard to some of the specific examples NRDC raised, we
acknowledge that vocal modifications of low-frequency cetaceans in
response to distant sound sources have been detected. However, as
discussed elsewhere in this Notice, not every behavioral change or
minor vocal modification rises to the level of a take or has any
potential to adversely impact marine mammal fitness, and NRDC has not
demonstrated why it believes the short duration exposures that low-
frequency cetaceans might be exposed to a few times a year from a
survey should constitute a ``high'' versus ``medium'' consequence in
NMFS's assessment framework.
Similarly, NMFS is also aware of the Videsen et al. (2017) paper
reporting the lower-level communication calls between humpback mother-
calf pairs and noting the increased risk of cow-calf separation with
increases in background noise. We first note that only neonates were
tagged and measured in this study (i.e., circumstances could change
with older calves). Further, while vocalizations between these pairs
are comparatively lower level than between adults, the cow and neonate
calf are in regular close proximity (as evidenced by the extent of
measured sound generated by rubbing in this study), which means that
the received levels for cow-calf communication are higher than they
would be if the animals were separated by the distance typical between
adults--in other words, it is unclear whether these lower-level, but
close proximity, communications are comparatively more susceptible to
masking. Assuming that right whale cow-calf pairs use the same lower-
level communication calls, we first note that across all five surveys,
modeled results estimate that 19 right whales may intercept with the
tracklines of the surveys such that they are potentially taken and,
further, as described in the ``Negligible Impact Analyses and
Determinations'' section and based on available demographic
information, it should be expected that no more than four exposures
could be of adult females with calves (not
[[Page 63278]]
specifically neonates). Again, when this very low likelihood of
encountering cow-calf pairs is combined with the fact that any
individuals (or cow-calf pairs) would not be expected to be exposed on
more than a couple/few days in a year, NRDC has not demonstrated how
the consequences of these activities would be ``catastrophic,'' for
right whales, and we believe our analysis supports a ``medium''
consequence rating.
Last, in response to the suggestion that we utilize a model, such
as the model NMFS used for assessing similar potential impacts in the
Gulf of Mexico, to assess impacts to communication space from the
surveys evaluated here--it is neither necessary nor an appropriate use
of those tools. As noted above, the combination of the modeled take
estimates, along with a qualitative evaluation of the temporal and
spatial footprint of the activities within the large action area and
dispersed marine mammal distributions, makes it clear that masking
effects, if any, would be highly limited for these activities. In the
Gulf of Mexico, NMFS used the referenced model in the context of a
five-year rule to programmatically assess the chronic impacts of an
entire seismic program in a mature and active hydrocarbon-producing
region, with a significantly greater amount of effort than is
contemplated in these five surveys, overlaid in an area with already
otherwise high ambient noise. Use of the model is comparatively
expensive and time-consuming, and produces a relatively gross-scale
comparison of predicted annual averages (or other duration) of
accumulated sound energy (which can also be interpreted in the context
of the communication space of any species). This sort of analysis can
be helpful in understanding relative chronic effects when higher and
longer-term overall levels of activity and impacts are being evaluated
across areas with notably variable levels of activities and/or ambient
noise, and can potentially inform decisions regarding time-area
mitigation. Here, however, any impacts to communication space from any
individual survey are expected to be minimal; in addition to being
unnecessary, the lack of granularity in the suggested model (which is
appropriate at larger and denser scales of impacts, and which can be
improved with improvement of the available input data) is such that its
application to these activities would not produce useful information.
Comment: The South Carolina Environmental Law Project, on behalf of
the Business Alliance for Protecting the Atlantic Coast, commented that
chronic stress is possible from the specified activities and that
likely stress effects would be exacerbated due to their contention that
avoidance is impossible.
Response: As described in our Notice of Proposed IHAs, NMFS
recognizes that stress from acoustic exposure is one potential impact
of these surveys, and that chronic stress can have fitness,
reproductive, etc. impacts at the population-level scale. However, we
believe the possibility for chronic stress is low given the transitory
and intermittent nature of the sound source (i.e., acoustic exposure in
specific areas will not be long lasting). The potential for chronic
stress was evaluated in making the determinations presented in NMFS's
negligible impact analyses.
Comment: An individual stated that NMFS did not account for long-
term impacts to species, writing that it is impossible to accurately
account for impacts without looking at the effects of sound disturbance
on energy balance (e.g., when disturbance results in additional time
spent traveling and/or foraging in less optimal habitats, the result
may be a negative energy balance). The commenter stated further that
this negative energy balance could have effects both individually and
cumulatively for a population, and that the cumulative effect of
behavioral disturbance could be equivalent to a certain amount of
lethal takes.
Response: NMFS acknowledges that the concerns raised are
theoretically possible, but in this case, with limited duration of
individual surveys or of overlap of multiple surveys, and modeled take
estimates suggesting that individuals would rarely be impacted by any
given survey more than a few days in a year, frequent and long-term
displacement is not expected. Therefore, NMFS does not anticipate
behavioral disruptions sufficient to negatively impact individual
energy balances, much less to a degree where long-term effects
resulting in impacts to recruitment or survival would occur. For
example, while the available evidence indicates sensitivity to
disruption of foraging efficiency for sperm whales exposed to airgun
noise (Miller et al., 2009), a recent bioenergetic modeling exercise
showed that infrequent, minor disruptions in foraging--as are expected
in this case--are unlikely to be fatal (Farmer et al., 2018). The
authors conclude that foraging disruptions would have to be relatively
frequent to lead to terminal starvation, but continual minor
disruptions can cause substantial reductions in available reserves.
Given the temporary, infrequent nature of exposure likely to result
from the planned surveys, in conjunction with the planned mitigation,
which includes effort restrictions in areas expected to be of
importance for sperm whale foraging, it is unlikely that either
continual minor disruptions or less frequent, but more severe
disruptions would occur.
Comment: One individual cited Schnitzler et al. (2017) in stating
that the varied anatomy of individual sperm whale ears indicates that
``tolerable'' sound levels may not be the same for different animals.
Response: NMFS acknowledges that actual individual responses to
noise exposure will vary based on a variety of factors, including
individual anatomy but more likely because of individual context and
experience. However, sufficient scientific information does not exist
to assess differential impacts to specific individuals. Therefore, NMFS
uses generic acoustic thresholds in order to predict potential
responses to noise exposure. However, NMFS has required a sufficiently
robust suite of mitigation measures to provide reasonable certainty of
general reduction of takes and of intensity and/or duration of acoustic
exposures for individual sperm whales.
Comment: The Bald Head Island Association noted that many marine
mammals have washed up on their beaches in recent years, including a
beaked whale and juvenile dolphin after offshore airgun surveys. Sea
Shepherd Legal claimed that NMFS did not adequately address the
potential for stranding events, noting several studies that they claim
link strandings with airgun surveys. They also noted that NMFS did not
acknowledge a January 2017 mass stranding of false killer whales when
considering impacts to species.
Response: Marine mammals are known to strand for a variety of
reasons, such as infectious agents, biotoxicosis, starvation, fishery
interaction, ship strike, unusual oceanographic or weather events,
sound exposure, or combinations of these stressors sustained
concurrently or in series (e.g., Geraci et al., 1999). However, the
cause or causes of most strandings are unknown (e.g., Best, 1982).
Stranding events are known to occasionally happen as a result of sound
exposure, e.g., Southall et al., 2006, 2013; Jepson et al., 2013;
Wright et al., 2013, with stranding thought to occur subsequent to the
exposure, as a result of non-auditory physiological effects or
injuries, which theoretically might occur as a secondary effect of
extreme behavioral reactions (e.g., change in dive profile as a result
of an avoidance reaction). However, such events are typically
associated with use of military
[[Page 63279]]
tactical sonar, which has very different characteristics than airgun
noise.
NMFS is unaware of any information linking possible strandings on
Bald Head Island, or in any other location on the East Coast, with
offshore airgun survey activity, and does not expect the planned
surveys to have any potential to result in stranding events or the type
of injuries or effects that could lead to stranding events, given the
required mitigation and operational protocols. In support of its
position, Sea Shepherd Legal cites two review articles (Gordon et al.,
2003; Compton et al., 2008) that make general statements regarding the
potential effects of airgun noise and/or review best practices in
mitigation--NMFS reviewed these papers and discussed them in our Notice
of Proposed IHAs. Sea Shepherd also cites a third document (Engel et
al., 2004) questioning whether such surveys may be responsible for
coincident strandings of humpback whales in Brazil in 2002, and notes
NMFS's discussion of a 2002 beaked whale stranding event that was
contemporaneous with and reasonably associated spatially with an airgun
survey in the Gulf of California. However, unlike for strandings
associated with use of military sonar, no conclusive causal link was
made, and these observations remain based on spatial and/or temporal
coincidence. NMFS here acknowledges the 2017 stranding of false killer
whales in Florida referenced by Sea Shepherd Legal, for which no cause
was found.
However, as a precaution NMFS has modified its reporting
requirements to include protocols relating to minimization of
additional harm to live-stranded (or milling) marine mammals. Addition
of these protocols does not imply any change to our determination that
stranding events are unlikely, nor does it imply that a stranding event
that does occur is necessarily the result of the specified activities.
However, we recognize that regardless of the cause of a stranding
event, it is appropriate to take action in certain circumstances to
avoid additional harm. Please see ``Monitoring and Reporting'' for more
information.
Marine Mammal Impacts--Habitat
Comment: Many commenters expressed concern regarding potential
impacts to marine mammal prey and/or food webs from the planned
surveys. NRDC specifically provided numerous citations in claiming that
the surveys could impact marine mammal prey through the following: (1)
Cause severe physical injury and mortality; (2) damage hearing and
sensory abilities of fish and marine invertebrates; (3) impede
development of early life history stages; (4) induce stress that
physically damages marine invertebrates and compromises fish health;
(5) cause startle and alarm responses that interrupt vital behaviors;
(6) alter predator avoidance behavior that may reduce probability of
survival; (7) affect catchability of prey species; (8) mask important
biological sounds essential to survival; (9) reduce reproductive
success, potentially jeopardizing long-term sustainability of fish
populations; (10) interrupt feeding behaviors and induce other species-
specific effects that may increase risk of starvation, reduce
reproduction, and alter community structure; and (11) compromise
orientation of fish larvae with potential ecosystem-level effects.
Additionally, many commenters cited a recent publication by McCauley et
al. (2017) as evidence that the surveys could potentially impact
zooplankton and consequently marine mammal food webs.
In contrast, the International Association of Geophysical
Contractors, American Petroleum Institute, and National Ocean
Industries Association (hereafter, ``the Associations'') stated that
McCauley et al. (2017) ``purports to demonstrate, but fails to prove,
that seismic survey air sources negatively impact zooplankton.'' The
Associations cite small sample size, variability in the baseline and
experimental data, and the ``large number of speculative conclusions
that appear to be inconsistent with the data collected over a two-day
period'' in stating that the research ``creates no reasonable
implication regarding the potential effects of seismic surveys on
marine mammals.''
Response: NMFS strongly disagrees with NRDC's contention that we
ignored effects to prey species; in fact, we considered relevant
literature (including that cited by NRDC) in finding that the most
likely impact of survey activity to prey species such as fish and
invertebrates would be temporary avoidance of an area, with a rapid
return to recruitment, distribution, and behavior anticipated. While
there is a lack of specific scientific information to allow an
assessment of the duration, intensity, or distribution of effects to
prey in specific locations at specific times and in response to
specific surveys, NMFS's review of the available information does not
indicate that such effects could be significant enough to impact marine
mammal prey to the extent that marine mammal fitness would be affected.
A more detailed discussion is provided in ``Potential Effects of the
Specified Activities on Marine Mammals and Their Habitat.''
In summary, fish react to sounds which are especially strong and/or
intermittent low-frequency sounds, and behavioral responses such as
flight or avoidance are the most likely effects. However, the reaction
of fish to airguns depends on the physiological state of the fish, past
exposures, motivation (e.g., feeding, spawning, migration), and other
environmental factors. While we agree that some studies have
demonstrated that airgun sounds might affect the distribution and
behavior of some fishes, potentially impacting foraging opportunities
or increasing energetic costs (e.g., Fewtrell and McCauley, 2012;
Pearson et al., 1992; Skalski et al., 1992; Santulli et al., 1999;
Paxton et al., 2017), other studies have shown no or slight reaction to
airgun sounds (e.g., Pena et al., 2013; Wardle et al., 2001; Jorgenson
and Gyselman, 2009; Cott et al., 2012). Most commonly, though, the
impacts of noise on fish are temporary. Investigators reported
significant, short-term declines in commercial fishing catch rate of
gadid fishes during and for up to five days after survey operations,
but the catch rate subsequently returned to normal (Engas et al., 1996;
Engas and Lokkeborg, 2002); other studies have reported similar
findings (Hassel et al., 2004).
As discussed by NRDC, however, even temporary effects to fish
distribution patterns can impact their ability to carry out important
life-history functions. SPLs of sufficient strength have been known to
cause injury to fish and fish mortality and, in some studies, fish
auditory systems have been damaged by airgun noise (McCauley et al.,
2003; Popper et al., 2005; Song et al., 2008). However, in most fish
species, hair cells in the ear continuously regenerate and loss of
auditory function likely is restored when damaged cells are replaced
with new cells. Halvorsen et al. (2012b) showed that a TTS of 4-6 dB
was recoverable within 24 hours for one species. Impacts would be most
severe when the individual fish is close to the source and when the
duration of exposure is long--both of which are conditions unlikely to
occur during these surveys, which will be transient in any given
location and likely result in brief, infrequent noise exposure to prey
species in any given area. For these surveys, the sound source is
constantly moving, and most fish would likely avoid the sound source
prior to receiving sound of sufficient intensity to cause physiological
or anatomical damage. In addition, ramp-up may
[[Page 63280]]
allow certain fish species the opportunity to move further away from
the sound source.
Available data suggest that cephalopods are capable of sensing the
particle motion of sounds and detect low frequencies up to 1-1.5 kHz,
depending on the species, and so are likely to detect airgun noise
(Kaifu et al., 2008; Hu et al., 2009; Mooney et al., 2010; Samson et
al., 2014). Auditory injuries (lesions occurring on the statocyst
sensory hair cells) have been reported upon controlled exposure to low-
frequency sounds, suggesting that cephalopods are particularly
sensitive to low-frequency sound (Andre et al., 2011; Sole et al.,
2013). Behavioral responses, such as inking and jetting, have also been
reported upon exposure to low-frequency sound (McCauley et al., 2000b;
Samson et al., 2014). Similar to fish, however, the transient nature of
the surveys leads to an expectation that effects will be largely
limited to behavioral reactions and would occur as a result of brief,
infrequent exposures.
With regard to potential impacts on zooplankton, McCauley et al.
(2017) found that exposure to airgun noise resulted in significant
depletion for more than half the taxa present and that there were two
to three times more dead zooplankton after airgun exposure compared
with controls for all taxa, within 1 km of the airguns. However, the
authors also stated that in order to have significant impacts on r-
selected species such as plankton, the spatial or temporal scale of
impact must be large in comparison with the ecosystem concerned, and it
is possible that the findings reflect avoidance by zooplankton rather
than mortality (McCauley et al., 2017). In addition, the results of
this study are inconsistent with a large body of research that
generally finds limited spatial and temporal impacts to zooplankton as
a result of exposure to airgun noise (e.g., Dalen and Knutsen, 1987;
Payne, 2004; Stanley et al., 2011).
A modeling exercise was conducted as a follow-up to the McCauley et
al. (2017) study (as recommended by McCauley et al. (2017)), in order
to assess the potential for impacts on ocean ecosystem dynamics and
zooplankton population dynamics (Richardson et al., 2017). Richardson
et al. (2017) found that for copepods with a short life cycle in a
high-energy environment, a full-scale airgun survey would impact
copepod abundance up to three days following the end of the survey,
suggesting that effects such as those found by McCauley et al. (2017)
would not be expected to be detectable downstream of the survey areas,
either spatially or temporally. However, these findings are relevant
for zooplankton with rapid reproductive cycles in areas where there is
a high natural replenishment rate resulting from new water masses
moving in, and the findings may not apply in lower-energy environments
or for zooplankton with longer life-cycles. In fact, the study found
that by turning off the current, as may reflect lower-energy
environments, the time to recovery for the modelled population extended
from several days to several weeks.
However, while potential impacts to zooplankton are of obvious
concern with regard to their follow-on effects for higher-order
predators, the survey area is not an important area for feeding for
taxa that feed directly on zooplankton, i.e., mysticetes. In the
absence of further validation of the McCauley et al. (2017) findings,
if we assume a worst-case likelihood of severe impacts to zooplankton
within approximately 1 km of the acoustic source, the large spatial
scale and expected wide dispersal of survey vessels does not lead us to
expect any meaningful follow-on effects to the prey base for odontocete
predators. While the large scale of effect observed by McCauley et al.
(2017) may be of concern, especially in a more temperate environment,
NMFS concludes that these findings indicate a need for more study,
particularly where repeated noise exposure is expected--a condition
unlikely to occur in relation to these planned surveys. We do not offer
further comment with regard to the specific criticisms of the
Associations, other than to say that their dismissal of the study seems
to reflect an unsubstantiated opinion.
Overall, prey species exposed to sound might move away from the
sound source, experience TTS, experience masking of biologically
relevant sounds, or show no obvious direct effects. Mortality from
decompression injuries is possible in close proximity to a sound, but
only limited data on mortality in response to airgun noise exposure are
available (Hawkins et al., 2014). The most likely impacts for most prey
species in a given area would be temporary avoidance of the area. The
surveys are expected to move through an area relatively quickly,
limiting exposure to multiple impulsive sounds. In all cases, sound
levels would return to ambient once a survey ends and the noise source
is shut down and, when exposure to sound ends, behavioral and/or
physiological responses are expected to end relatively quickly
(McCauley et al., 2000b). The duration of fish avoidance of a given
area after survey effort stops is unknown, but a rapid return to normal
recruitment, distribution, and behavior is anticipated. While the
potential for disruption of spawning aggregations or schools of
important prey species can be meaningful on a local scale, the mobile
and temporary nature of the surveys and the likelihood of temporary
avoidance behavior suggest that impacts would be minor.
Comment: A group of scientists (C.W. Clark, S.D. Kraus, D.P.
Nowacek, A.J. Read, M. Rekdahl, A.N. Rice, H. Rosenbaum, and R.S.
Schick) submitted a collective comment letter. Hereafter, we refer to
this letter as ``Nowacek et al.'' Nowacek et al. and NRDC stated that
it is inappropriate to conclude that these surveys will not impact
marine mammal acoustic habitat, since the production of airgun noise is
known to increase ambient noise, thereby negatively impacting habitat.
NRDC further states that NMFS has failed to adequately account for
impacts to acoustic habitat. In support of their statements, Nowacek et
al. submitted the results of a sound field modeling exercise in which
they considered energy produced from seven shots of a 40-element array
at 6 m depth (other important source details were not provided) across
one-third-octave bands spanning the 71-224 Hz frequency range.
Resulting sound fields were concatenated at 1-s resolution for two
different water depths (50 and 200 m) (commenters submitted animations
associated with this exercise; these are available upon request and are
part of our administrative record for these actions). They wrote that
these animations highlight the dynamic nature of the marine
environment, especially the low-frequency sound field, and the large
area over which sound levels are increased above ambient levels but
below current regulatory harassment thresholds. The commenters then
correctly note that consideration of likely takes is limited to just a
portion of the area over which airgun noise extends into the marine
environment. Nowacek et al. also recommended that NMFS produce a
quantitative methodology for assessing the region's acoustic
environment, the proportional contributions from each of the natural
and anthropogenic noise inputs, and create mechanisms to mitigate these
lower-level noise exposures.
Response: The commenters' claims that NMFS concluded that there
``would be no impact to the quality of the acoustic habitat'' or
suggested that ``there is no basis for acoustic habitat impacts'' are
erroneous. NMFS made no such statements, but rather
[[Page 63281]]
acknowledged in our Notice of Proposed IHAs that it was likely that
there would be impacts to acoustic habitat, particularly for low-
frequency cetaceans. In fact, we explicitly considered this likelihood
in our preliminary negligible impact analyses, finding that
``consequence'' of the surveys should be considered as higher for
mysticete whales than for other species for this reason.
NMFS addressed potential effects to habitat, including acoustic
habitat, and acknowledges that the surveys will increase noise levels
in the vicinity of operating source vessels. However, following
consideration of the available information, NMFS concludes that these
impacts will not significantly affect ambient noise levels or acoustic
communication space over long time periods, especially in the context
of any given exposed individual. As described previously, exploratory
surveys such as these cover a large area but would be transient rather
than focused in a given location over time and therefore would not be
considered as contributing meaningfully to chronic effects in any given
location. Given these conclusions, a separate quantitative analysis of
potential impacts to acoustic habitat, as is suggested by Nowacek et
al., is not warranted. In contrast, we did develop and perform such
analysis for a different assessment of much more extensive geophysical
survey activity (see Appendix K in BOEM, 2017) to be conducted over a
period of ten years, versus the limited amount of survey activity to be
conducted over a period of one year here.
We acknowledge and appreciate the commenters' scientific expertise,
but there are relevant statutory and regulatory requirements that
inform NMFS in the scope of analysis relevant to a finding of
negligible impact. Please see also our response to a previous comment
above, in which NRDC makes similar charges regarding the impacts of
masking. Finally, regarding terminology used in the comments (i.e.,
``primary constituent elements''), the discussion in this document
pertains specifically to the MMPA and not components related to
critical habitat designated under the ESA.
Comment: The Sierra Club Marine Group noted that Cape Hatteras has
a very unique morphology, and that these features support upwelling
that supports significant biodiversity, including beaked whales. The
commenters stated that impacts to this habitat provide a compelling
reason to deny the IHAs.
Response: As described in our Notice of Proposed IHAs, NMFS concurs
that Cape Hatteras provides important habitat for a diverse assemblage
of species, particularly for species such as sperm whales, beaked
whales, pilot whales, and other species that show high site fidelity to
the area. Accordingly, NMFS has designed a time-area restriction
encompassing the area referenced in the comment that precludes survey
effort within the area for a three-month period (January to March;
Stanistreet et al., 2018); the restriction is defined specifically to
benefit beaked whales, sperm whales, and pilot whales, with the
specific timing intended as the most appropriate for sperm whales. We
also require mitigation to reduce the intensity and duration of
exposure for these species--particularly for acoustically sensitive
species, such as beaked whales, for which shutdown is required at an
extended distance of 1.5 km. Separately, NMFS has required year-round
closures of similar high-relief habitats further offshore that are
predicted to host relatively high densities of beaked whales. In
addition, the North Atlantic right whale closure will protect portions
of the area referenced by the commenters, as it extends out to 90 km
from the coastline (i.e., 80 km plus a 10 km buffer, see
``Mitigation'') and is in effect from November through April (or
comparable protection provided through implementation of a NMFS-
approved mitigation and monitoring plan at distances between 47-80 km
offshore), whereas the seasonal restriction off of Cape Hatteras is in
effect from January through March. NMFS believes these restrictions
provide a high degree of protection to these species and the habitat
they utilize around Cape Hatteras, while meeting the MMPA's least
practicable adverse impact standard. When the contextual factor
addressing required mitigation is considered, the outcome is a
negligible impact to affected species.
Comment: An individual states that the surveys have the potential
to impair the Chesapeake Bay, and that such impairment would have wider
ecological and economic repercussions beyond the scope of impacting
marine mammals. Similarly, one group mentioned that impacts from the
surveys could ripple into smaller bays and inlets elsewhere along the
East Coast, and impact species long after surveys are complete.
Response: NMFS's action is authorizing the taking of marine mammals
pursuant to section 101(a)(5)(D); therefore, impacts of the survey on
aspects of the environment other than marine mammals and their habitat
are not relevant to NMFS's analysis conducted pursuant to the MMPA.
However, the authorization of marine mammal take incidental to the
planned surveys would not impact marine mammals of the Chesapeake Bay
or of other coastal bays and estuaries. Surveys may not operate closer
than 30 km to shore at any time.
North Atlantic Right Whale
Comment: Many commenters expressed concern regarding the North
Atlantic right whale and potential impacts of the specified activities,
given their declining population size, an ongoing Unusual Mortality
Event (UME), declining calf production, and annual exceedances of the
calculated potential biological removal value (see ``Description of
Marine Mammals in the Area of the Specified Activities--North Atlantic
Right Whale'' for further discussion of these issues). Some commenters
noted additional concern regarding potential survey overlap with
biologically important areas. Others highlighted concerns regarding
increased risk of ship strike and/or entanglement with survey vessels,
in addition to the potential for acoustic and behavioral effects.
Response: NMFS appreciates the concerns expressed by commenters
regarding right whales. As an agency, NMFS is working to address the
numerous issues facing right whales, including continued work to reduce
deaths due to ship strike and entanglement in fishing gear and ongoing
investigation of the UME, as well as other measures to investigate and
address the status of the species. The best available scientific
information shows that the majority of right whale sightings in the
southeast occur in right whale calving areas from roughly November
through April, with individual right whales migrating to and from these
areas through mid-Atlantic shelf waters. Because of these concerns
regarding right whales, NMFS is requiring closure of these areas (out
to 90 km from shore) to survey activity from November 1 to April 30 (or
that comparable protection is achieved through implementation of a
NMFS-approved mitigation and monitoring plan at distances between 47-80
km offshore). This measure is expected to largely avoid disruption of
behavioral patterns for right whales and to minimize overall acoustic
exposures. Therefore, NMFS believes that this restriction provides for
migratory passage to and from calving grounds as well as avoiding
impacts to the whales while on the grounds. In addition, NMFS re-
evaluated potential right whale takes using the best available
[[Page 63282]]
scientific information (i.e., Roberts et al., 2017) and in
consideration of the revised time-area restriction. The result of this
analysis shows that takes of right whales will be minimal.
Comment: NRDC and, separately, Nowacek et al. state that airgun
surveys have been linked to significant reductions in the probability
of calf survival in western Pacific gray whales (another endangered
baleen whale population), claiming that these findings indicate that
similar surveys off the southeastern U.S will have significant negative
effects on the whales that occur anywhere in the region.
Response: Commenters cite a preliminary report (Cooke et al., 2015)
that documented a reduction in calf survival that they suggested may be
related to disruption of foraging from airgun survey activity and pile
driving in Russia due to presumed avoidance of foraging areas. However,
a more recent analysis (Cooke et al., 2017) invalidated these findings,
showing that this was a sampling effect, as those calves that were
assumed dead in the 2015 study have since been observed alive
elsewhere. The new study found no significant annual variation in calf
survival. Johnson et al. (2007) had previously reported that foraging
gray whales exposed to airgun sounds during surveys in Russia did not
experience any biologically significant or population-level effects.
Comment: J.J. Roberts and P.N. Halpin of the Duke University Marine
Geospatial Ecology Lab (hereafter, ``MGEL'') provided two comments
related to right whales. First, the commenters stated, in summary, that
the time-area restriction included in our Notice of Proposed IHAs for
the specific purpose of avoiding impacts to the North Atlantic right
whale would not be sufficient to achieve its stated purpose. The
commenters noted multiple lines of scientific evidence that right
whales occur beyond the area defined in the Notice of Proposed IHAs
(i.e., a 20-nmi coastal strip, superseded by either critical habitat or
seasonal management areas, and buffered by a distance of 10 km; this
equates roughly to a 47-km coastal strip). The commenters also
reiterated concern regarding an error associated with the right whale
take estimates for two applicants (TGS and Western). Finally, the
commenters noted that they were developing updated density models for
the right whale; these revised models more than double the survey
effort utilized by the models in the region south of Cape Hatteras,
while additional new data boost coverage in non-summer seasons. As
stated by the commenters, collectively these data allow for a notable
upgrade in right whale density model performance in the regions and
seasons addressed here. The commenters noted that, while the revised
models have not been through formal peer review, they utilize the same
methodology as the Roberts et al. (2016) publication, which has been
peer reviewed.
Response: We agree with these comments, and addressed them through
use of the revised North Atlantic right whale models (Roberts et al.,
2017) in developing new exposure estimates for all five applicant
companies. Importantly, in agreement with the statements of the
commenters and with the outputs of the revised models, we revised the
time-area restriction by increasing the standoff distance from shore to
90 km (i.e., 80 km plus a 10 km buffer) (or requiring that comparable
protection is achieved through implementation of a NMFS-approved
mitigation and monitoring plan at distances between 47-80 km offshore).
As stated by MGEL and other commenters, Norris et al. (2014) reported
acoustic detections of right whales in the southeast beyond the
previous 47 km limit, while Foley et al. (2011) documented a right
whale birth beyond the previous limit. The right whale model produced
by Roberts et al. (2016) explicitly included distance from shore as a
predictor in the model; right whale densities significantly above zero
were predicted beyond the proposed 47 km limit. The revised model
retains distance from shore as a predictor and, in the region north of
Cape Fear, indicates that right whale density peaks at about 50 km
offshore during the winter and is moderate to about 80 km from shore,
beyond which limit density is predicted as dropping off rapidly. Please
see ``Estimated Take--North Atlantic Right Whale'' and ``Mitigation''
for additional discussion.
Comment: Nowacek et al. commented that NMFS should perform a
quantitative evaluation of right whale health and reproductive rates,
including mortality and sublethal effects of entanglement. They noted
that tools such as the Population Consequences of Disturbance (PCOD)
model could be used to perform such an analysis. However, Nowacek et
al. provided their own modeling example, including a health assessment
of five North Atlantic right whales, which they described in their
comment letter. Nowacek et al.'s analysis showed that a small decrement
in health that could be linked to stress caused by chronic noise
exposure can result in negative consequences for individual right
whales.
Response: NMFS appreciates the attention given to this issue by the
commenters, and finds the analysis provided in their letter useful. As
noted by many commenters, the primary threats to the right whale remain
ship strike and entanglement in fishing gear. However, NMFS considered
this analysis and its conclusions in its determination to revisit the
acoustic exposure analysis conducted for right whales and in
reconsidering the most appropriate habitat-based mitigation
requirements related to right whales. Following these new analyses,
NMFS finds that predicted takes of right whales have been substantially
reduced and that potential impacts to the right whale have been reduced
to the level of least practicable adverse impact. While it is likely
not possible to completely avoid acoustic exposures of North Atlantic
right whales, NMFS finds that such exposures will be minimized and
that, importantly, the impact of acoustic exposures will be minimized
by avoiding entirely the habitat expected to be important for right
whales for calving and migratory behavior (or that comparable
protection is achieved through implementation of a NMFS-approved
mitigation and monitoring plan at distances between 47-80 km offshore).
In the event that right whales are encountered outside these areas, the
expanded shutdown requirement will minimize the severity and/or
duration of acoustic exposures. Finally, while exposures of right
whales at levels below those expected to result in disruption of
behavioral patterns but above the level of ambient noise may occur,
NMFS does not consider such potential exposures as likely to constitute
``chronic noise exposure,'' as a result of the relatively brief
duration of any given survey in any particular location; therefore, it
is unlikely that the specified activities could result in impacts such
as those assessed through the analysis of Nowacek et al.
Comment: One commenter described the relationship between noise and
stress shown by Rolland et al. (2012) for right whales, stating that
the planned surveys could increase stress in right whales.
Response: While NMFS concurs that the findings of Rolland et al.
(2012) indicate a connection between noise exposure and stress in right
whales, the number of vessels associated with the surveys is unlikely
to contribute to significant additive vessel traffic and associated
vessel noise as compared with vessel activity already occurring in the
region. Rolland et al. (2012)
[[Page 63283]]
measured vessel density in an area with much more concentrated activity
(i.e., shipping lanes in the Bay of Fundy) than what would occur in the
activity area. While noise from the surveys, whether due to use of the
airgun arrays or from the vessels themselves, may cause stress
responses in exposed animals, NMFS finds it unlikely that such
responses will significantly impact individual whales as chronic noise
exposure is not expected.
Comment: Several groups commented on additional data NMFS should
have considered in assessing impacts to North Atlantic right whales.
For example, the Marine Mammal Commission (MMC) recommended that we
consult with NMFS's Northeast Fisheries Science Center regarding
results of their most recent acoustic analysis, which they contend may
provide insight on occurrence of right whales at different distances
from shore. Similarly, Nowacek et al. recommended that NMFS should
consider more recent data from the Atlantic Marine Assessment Program
for Protected Species (AMAPPS) surveys or right whale surveys in the
southeast curated by the North Atlantic Right Whale Consortium. NRDC
stated that NMFS must use additional data sources in calculating right
whale densities, noting that recent passive acoustic studies have
detected whales further offshore and with broader seasonality than
previously expected.
Response: NMFS agrees with these comments, and has considered these
various sources of newer data, including by revising acoustic exposure
estimates for right whales by using the latest density models for right
whales (Roberts et al., 2017). These revised models incorporate the
southeast U.S. right whale survey data as well as the AMAPPS data.
While the revised model does not directly incorporate acoustic data--we
note that NRDC offers no suggestions as to how this might be
accomplished--it was validated through comparison with passive acoustic
monitoring data (Davis et al., 2017). While this validation work does
suggest that the revised model may underestimate right whale presence
in certain locations or seasons--for example, acoustic data indicate
that the model may underestimate the presence of whales relatively far
from shore during the winter in the region north of Cape Hatteras--we
developed an extended right whale closure (out to 90 km from shore) (or
we require that comparable protection is achieved through
implementation of a NMFS-approved mitigation and monitoring plan at
distances between 47-80 km offshore) in an effort to reasonably
encompass the likelihood of increased whale presence at greater
distances from shore than have previously been expected.
Comment: Sea Shepherd Legal stated that NMFS ignored the ``Cetacean
& Sound Mapping platform (``CetSound'')'' when discussing biologically
important areas for North Atlantic right whales.
Response: Though NMFS did not give specific reference to
``CetSound'' in our Notice of Proposed IHAs, we did in fact incorporate
and consider information available through NOAA's CetSound website
(cetsound.noaa.gov), including information relating to BIAs, as
discussed by LaBrecque et al. (2015).
Cumulative Impacts and Related Issues
Comment: Many commenters expressed concern regarding
``cumulative,'' ``aggregate'' and ``synergistic'' impacts. Commenters
stated that NMFS did not adequately address cumulative or aggregate
impacts from the five surveys, which are planned to occur within the
same broad geographic region and which could overlap temporally. Some
commenters referenced the large amount of survey effort described in
BOEM's PEIS, erroneously ascribing the potential cumulative impacts
associated with that level of effort--associated with nine years of
surveys in support of an active oil and gas program in the Atlantic--to
the significantly smaller amount of activity contemplated in our five
separate proposed IHAs. Commenters urged the agency to review
cumulative impacts using a risk-averse approach, considering such
impacts in the context of effects to both species and ecosystems, as
well as across time and geographic extent. As discussed in a previous
comment response, some commenters cited studies demonstrating potential
long-range propagation of airgun signals as reason for additional
consideration of cumulative impacts. Similarly, some commenters claimed
a need to consider takes in the aggregate and to consider potential
takes from other sources. Nowacek et al. specified that NMFS should
assess aggregate impacts in addition to cumulative impacts,
highlighting available tools to do so. One commenter suggested that a
cumulative noise management plan should be developed. Commenters such
as Nowacek et al. decry our independent consideration of the effects of
each individual specified activity under the MMPA as ``completely
without basis in science or logic.'' Similarly, NRDC claims that
failing to consider the total impact of all five surveys in the
negligible impact assessment does not satisfy NMFS's legal obligations
and is ``contrary to common sense and principles of sound science.''
NRDC also states that NMFS's negligible impact determination
underestimates impacts to marine mammal species and populations because
it fails to consider the effects of other anticipated activities on the
same marine mammal populations. Finally, some commenters acknowledged
that the MMPA does not require consideration of cumulative impacts but
stated that NMFS must do so in this case given the unprecedented scale
of these surveys in the Atlantic.
Response: Cumulative impacts (also referred to as cumulative
effects) is a term that appears in the context of NEPA and the ESA, but
it is defined differently in those different contexts. Neither the MMPA
nor NMFS's codified implementing regulations address consideration of
other unrelated activities and their impacts on populations. However,
the preamble for NMFS's implementing regulations (54 FR 40338;
September 29, 1989) states in response to comments that the impacts
from other past and ongoing anthropogenic activities are to be
incorporated into the negligible impact analysis via their impacts on
the environmental baseline. Consistent with that direction, NMFS here
has factored into its negligible impact analyses the impacts of other
past and ongoing anthropogenic activities via their impacts on the
baseline (e.g., as reflected in the density/distribution and status of
the species, population size and growth rate, and other relevant
stressors (such as incidental mortality in commercial fisheries)). In
addition, the context aspect of our assessment framework also considers
these factors. See the ``Negligible Impact Analyses and
Determinations'' section of this notice.
Our 1989 final rule for the MMPA implementing regulations also
addressed public comments regarding cumulative effects from future,
unrelated activities. There we stated that such effects are not
considered in making findings under section 101(a)(5) concerning
negligible impact. We indicated that NMFS would consider cumulative
effects that are reasonably foreseeable when preparing a NEPA analysis;
and also that reasonably foreseeable cumulative effects would be
considered under section 7 of the ESA for ESA-listed species.
In this case, we deem each of these IHAs a future, unrelated
activity relative to the others. Although these IHAs are all for
surveys that will be conducted for
[[Page 63284]]
a similar purpose, they are unrelated in the sense that they are
discrete actions under section 101(a)(5)(D), issued to discrete
applicants.
Here, we recognize the potential for cumulative impacts, and that
the aggregate impacts of the five surveys will be greater than the
impacts of any given survey. The direct aggregate impacts of multiple
surveys were addressed through the associated NEPA analyses: In BOEM's
PEIS, which addressed the impacts of a significantly greater amount of
survey activity that may be permitted by BOEM, and which NMFS adopted
as the basis for its Record of Decision; as well as in NMFS's tiered
Environmental Assessment, which supported a Finding of No Significant
Impact (FONSI) for the issuance of the five IHAs here.
In our FONSI, NMFS's assessment was focused on whether the
predicted level of take from the five surveys, when considered in
context, would have a meaningful biological consequence at a species or
population level. NMFS, therefore, assessed and integrated other
contextual factors (e.g., species' life history and biology,
distribution, abundance, and status of the stock; mitigation and
monitoring; characteristics of the surveys and sound sources) in
determining the overall impact of issuance of the five IHAs on the
human environment. Key considerations included the nature of the
surveys and the required mitigation. In all cases, it is expected that
sound levels will return to previous ambient levels once the acoustic
source moves a certain distance from the area, or the surveys cease,
and it is unlikely that the surveys will all occur at the same time in
the same places, as the area within which the surveys will occur is
very large and some will occur for less than six months. In other
words, we would not expect the duration of a sound source to be greater
than moderate and intermittent in any given area. Surveys have been
excluded from portions of the total area deemed to result in the
greatest benefit to marine mammals. These restrictions will not only
reduce the overall numbers of take but, more importantly, will
eliminate or minimize impacts to marine mammals in the areas most
important to them for feeding, breeding, and other important functions.
Therefore, these measures are expected to meaningfully reduce the
severity of the takes that do occur by limiting impacts that could
reduce reproductive success or survivorship.
In summary, NMFS finds that when the required mitigation and
monitoring is considered in combination with the large spatial extent
over which the activities are spread across for comparatively short
durations (less than one year), the potential impacts are both
temporary and relatively minor. Therefore, NMFS does not expect
aggregate impacts from the five surveys to marine mammals to affect
rates of recruitment or survival, either alone or in combination with
other past, present, or ongoing activities. The cumulative impacts of
these surveys (i.e., the incremental impact of the action when added to
other past, present, and reasonably foreseeable future actions) were
addressed as required through the NEPA documents cited above and, as
noted, supported a FONSI for the five IHAs. These documents, as well as
the relevant Stock Assessment Reports, are part of NMFS's
Administrative Record for this action, and provided the decision-maker
with information regarding other activities in the action area that
affect marine mammals, an analysis of cumulative impacts, and other
information relevant to the determinations made under the MMPA.
Separately, cumulative effects were analyzed as required through
NMFS's required intra-agency consultation under section 7 of the ESA,
which concluded that NMFS's action of issuing the five IHAs was not
likely to jeopardize the continued existence of listed marine mammals
and was not likely to adversely affect any designated critical habitat.
We note that section 101(a)(5)(D) of the MMPA requires NMFS to make
a determination that the take incidental to a ``specified activity''
will have a negligible impact on the affected species or stocks of
marine mammals, and will not result in an unmitigable adverse impact on
the availability of marine mammals for taking for subsistence uses. We
believe the ``specified activity'' for which incidental take coverage
is being sought under section 101(a)(5)(D) is appropriately defined and
described by the IHA applicant, just as with applications submitted for
section 101(a)(5)(A) incidental take regulations. Here there are five
specified activities, with a separate applicant for each. NMFS must
make the necessary findings for each specified activity.
Comment: Several commenters discussed a recent report from the
National Academy of Sciences concerning cumulative impacts to marine
mammals (``Approaches to Understanding the Cumulative Effects of
Stressors on Marine Mammals''; NAS, 2017), suggesting that NMFS should
have reviewed this report in addressing cumulative impacts.
Response: NMFS acknowledges the importance of this new report,
which was not available at the time of writing for our Notice of
Proposed IHAs. We reviewed this report and considered its findings in
relation to our considerations pursuant to NEPA as well as with regard
to its general findings for marine mammals. Behavioral disturbance or
stress may reduce fitness for individual animals and/or may exacerbate
existing declines in reproductive health and survivorship. For example,
stressors such as noise and pollutants can induce responses involving
the neuroendocrine system, which controls reactions to stress and
regulates many body processes (NAS, 2017). As an example, Romano et al.
(2004) found that upon exposure to noise from a seismic watergun,
bottlenose dolphins had elevated levels of a stress-related hormone
and, correspondingly, a decrease in immune cells. Population-level
impacts related to energetic effects or other impacts of noise are
difficult to determine, but the addition of other stressors can add
considerable complexity due to the potential for interaction between
the stressors or their effects (NAS, 2017). When a population is at
risk NAS (2017) recommends identifying those stressors that may
feasibly be mitigated. In this case, we have done so by prescribing a
comprehensive suite of mitigation measures that both specifically
tailors real-time detection and mitigation requirements to the species
most sensitive to noise from airguns or to additional stressors in
general (due to overall vulnerability of the stock), and includes
habitat-based mitigation that restricts survey effort in the areas and
times expected to be most important for the species at greatest risk of
more severe impacts from the specified activities (or requires
comparable protection via other methods).
Acoustic Thresholds
Comment: NRDC and several other commenters criticized NMFS's use of
the 160-dB rms Level B harassment threshold, stating that the threshold
is based on outdated information and that current research shows that
behavioral impacts can occur at levels below the threshold. Criticism
of our use of this threshold also focused on its nature as a step
function, i.e., it assumes animals don't respond to received noise
levels below the threshold but always do respond at higher received
levels. Several organizations also suggest that reliance on this
threshold results in consistent underestimation of impacts. Commenters
urged the agency to provide additional technical acoustic guidance
regarding thresholds for behavioral harassment and stated that
[[Page 63285]]
no determinations regarding the proposed IHAs can be made until such
new guidance has been developed. NRDC specifically stated that NMFS
should employ specific thresholds for which species-specific data are
available, and then create generalized thresholds for other species,
and that the thresholds should be expressed as linear risk functions
where appropriate to account for intraspecific and contextual
variability. NRDC and others suggested that NMFS must revise the
threshold as suggested in Nowacek et al. (2015), which recommended a
dose function centered on 140 dB rms. TGS suggested that NMFS should
re-evaluate take estimates using the approach described in Wood et al.
(2012).
Response: NMFS acknowledges that the 160-dB rms step-function
approach is simplistic, and that an approach reflecting a more complex
probabilistic function may more effectively represent the known
variation in responses at different levels due to differences in the
receivers, the context of the exposure, and other factors. Certain
commenters suggested that our use of the 160-dB threshold implies that
we do not recognize the science indicating that animals may react in
ways constituting behavioral harassment when exposed to lower received
levels. However, we do recognize the potential for Level B harassment
at exposures to received levels below 160 dB rms, in addition to the
potential that animals exposed to received levels above 160 dB rms will
not respond in ways constituting behavioral harassment. These comments
appear to evidence a misconception regarding the concept of the 160-dB
threshold. While it is correct that in practice it works as a step-
function, i.e., animals exposed to received levels above the threshold
are considered to be ``taken'' and those exposed to levels below the
threshold are not, it is in fact intended as a sort of mid-point of
likely behavioral responses (which are extremely complex depending on
many factors including species, noise source, individual experience,
and behavioral context). What this means is that, conceptually, the
function recognizes that some animals exposed to levels below the
threshold will in fact react in ways that are appropriately considered
take, while others that are exposed to levels above the threshold will
not. Use of the 160-dB threshold allows for a simplistic quantitative
estimate of take, while we can qualitatively address the variation in
responses across different received levels in our discussion and
analysis.
NRDC consistently cites reports of changes in vocalization,
typically for baleen whales, as evidence in support of a lower
threshold than the 160-dB threshold currently in use. A mere reaction
to noise exposure does not, however, mean that a take by Level B
harassment, as defined by the MMPA, has occurred. For a take to occur
requires that an act have ``the potential to disturb by causing
disruption of behavioral patterns,'' not simply result in a detectable
change in motion or vocalization. Even a moderate cessation or
modification of vocalization might not appropriately be considered as
being of sufficient severity to result in take (Ellison et al., 2012).
NRDC claims these reactions result in biological consequences
indicating that the reaction was indeed a take but does not provide a
well-supported link between the reported reactions at lower received
levels and the claimed consequences. In addition, NRDC fails to discuss
documented instances of marine mammal exposure to received levels
greater than 160 dB that did not elicit any response. Just a few
examples are presented here:
Malme et al. (1985) conducted a study consisting of
playback using a stationary or moving single airgun and humpback
whales. No clear overall signs of avoidance of the area were recorded
for feeding/resting humpback whales exposed to received levels up to
172 dB. Although startle responses were observed when the airgun was
first turned on, likely due to the novelty of the sound, increasing
received levels did not result in increasing probability of avoidance.
In three instances, whales actually approached the airgun.
Malme et al. (1988) conducted a controlled exposure
experiment involving a moving single airgun and gray whales. From this
study, the authors predicted a 0.5 probability that whales would stop
feeding and move away from the area when received levels reached 173 dB
and a 0.1 probability of feeding interruption at a received level of
163 dB. However, whale responses were highly variable, with some whales
remaining feeding with received levels as high as 176 dB.
McCauley et al. (1998, 2000a, 2000b) report observations
associated with an actual seismic survey (array volume 2,678 in \3\)
and controlled approaches of humpback whales with a single airgun. When
exposed to the actual seismic survey, avoidance maneuvers for some
whales began at a range of 5-8 km from the vessel; however, in three
trials whales at a range beyond 5 km showed no discernible effects on
movement patterns. In addition, some male humpback whales were
attracted to the single airgun (maximum received level of 179 dB).
Overall, McCauley et al. (2000a) found no gross disruption of humpback
whale movements in the region of the source vessel, based on encounter
rates.
Malme et al. (1983, 1984) conducted playback experiments
with gray whales involving a single airgun and a full array (2,000-
4,000 in \3\). For playback of the array, it was estimated that
probability of avoidance during migration (including moving inshore and
offshore to avoid the area or to pass the noise source at a greater
distance then would normally occur) was 0.1 at 164 dB; 0.5 at 170 dB;
and 0.9 at levels greater than 180 dB.
These examples are related only to baleen whales, for which NRDC
provides examples of vocalization changes in response to noise
exposure. Although associated received levels are not available, a
substantial body of evidence indicates that delphinids are
significantly more tolerant of exposure to airgun noise. Based on
review of monitoring reports from many years of airgun surveys, many
delphinids approach acoustic source vessels with no apparent discomfort
or obvious behavioral change (Barkaszi et al., 2012; Stone, 2015a).
Behavioral observations of gray whales during an airgun survey
monitored whale movements and respirations pre-, during-, and post-
seismic survey (Gailey et al., 2016). Behavioral state and water depth
were the best `natural' predictors of whale movements and respiration
and, after considering natural variation, none of the response
variables were significantly associated with survey or vessel sounds.
Overall, we reiterate the lack of scientific consensus regarding
what criteria might be more appropriate. Defining sound levels that
disrupt behavioral patterns is difficult because responses depend on
the context in which the animal receives the sound, including an
animal's behavioral mode when it hears sounds (e.g., feeding, resting,
or migrating), prior experience, and biological factors (e.g., age and
sex). Other contextual factors, such as signal characteristics,
distance from the source, and signal to noise ratio, may also help
determine response to a given received level of sound. Therefore,
levels at which responses occur are not necessarily consistent and can
be difficult to predict (Southall et al., 2007; Ellison et al., 2012;
Bain and Williams, 2006).
There is currently no agreement on these complex issues, and NMFS
followed the practice at the time of submission and review of these
applications in assessing the likelihood
[[Page 63286]]
of disruption of behavioral patterns by using the 160-dB threshold.
This threshold has remained in use in part because of the practical
need to use a relatively simple threshold based on available
information that is both predictable and measurable for most
activities. We note that the seminal review presented by Southall et
al. (2007) did not suggest any specific new criteria due to lack of
convergence in the data. NMFS is currently evaluating available
information towards development of guidance for assessing the effects
of anthropogenic sound on marine mammal behavior. However, undertaking
a process to derive defensible exposure-response relationships is
complex (e.g., NMFS previously attempted such an approach, but is
currently re-evaluating the approach based on input collected during
peer review of NMFS (2016)). A recent systematic review by Gomez et al.
(2016) was unable to derive criteria expressing these types of
exposure-response relationships based on currently available data.
NRDC consistently cites Nowacek et al. (2015) in public comments,
suggesting that this paper is indicative of a scientific consensus that
NMFS is missing or ignoring. We note first that while NRDC refers to
this paper as a ``study'' (implying that it presents new scientific
data or the results of new analyses of existing scientific data), the
paper in fact makes policy recommendations rather than presenting any
new science. The more substantive reviews presented by Southall et al.
(2007) and Gomez et al. (2016) were unable to present any firm
recommendations, as noted above. Other than suggesting a 50 percent
midpoint for a probabilistic function, Nowacek et al. (2015) offer
minimal detail on how their recommended probabilistic function should
be derived/implemented or exactly how this midpoint value (i.e., 140 dB
rms) was derived (i.e., what studies support this point). In contrast
with elements of a behavioral harassment function that NRDC indicates
as important in their comments, Nowacek et al. (2015) does not make
distinctions between any species or species groups and provide no
quantitative recommendations for acknowledging that behavioral
responses can vary by species group and/or behavioral context. In
summary, little substantive support is provided by Nowacek et al.
(2015) for the proposal favored by NRDC and it is treated in that paper
as a vague recommendation with minimal support offered only in a one-
page supplementary document rather than well-supported scientific
consensus, as the commenter suggests.
NMFS disagrees that establishing species-specific thresholds is
practical (i.e., this approach would make assessments unnecessarily
onerous by creating numerous thresholds to evaluate). Additionally,
there is scientific evidence that grouping thresholds by broad source
category (Gomez et al., 2016) or taxonomic group (NMFS, 2018) is
supportable. NMFS currently uses data/thresholds from surrogate
species/groups to represent those species/groups where data are not
available.
Overall, while we agree that there may be methods of assessing
likely behavioral response to acoustic stimuli that better capture the
variation and context-dependency of those responses than the simple
step-function used here, there is no agreement on what that method
should be or how more complicated methods may be implemented by
applicants. NMFS is committed to continuing its work in developing
updated guidance with regard to acoustic thresholds, but pending
additional consideration and process is reliant upon an established
threshold that is reasonably reflective of available science.
In support of exploring new methods for quantitatively predicting
behavioral harassment, we note NMFS's recently published proposed
incidental take regulations for geophysical surveys in the Gulf of
Mexico (83 FR 29212; June 22, 2018), which propose using the modeling
study first published in BOEM's associated EIS (Appendix D in BOEM,
2017) to estimate take. This study evaluated potential disruption of
behavioral patterns that could result from a program of airgun surveys,
using both the 160-dB step function and a probabilistic risk function
similar to that suggested by Nowacek et al. (2015), but with a midpoint
set at 160 dB for the majority of species, rather than 140 dB. This
function, described in Wood et al. (2012), includes for most species a
10 percent probability of behavioral harassment at 140 dB, with
subsequent steps of 50 percent at 160 dB and 90 percent at 180 dB. Of
note, use of this generic function resulted in lower numbers of
estimated takes than did use of the 160-dB step function. Therefore,
while use of the probabilistic risk function may allow for more
specific quantitative consideration of contextual issues and variation
in individual responses, our use of the 160-dB step function is
conservative in that the number of resulting takes is higher. NMFS will
continue to explore quantitative refinement of the behavioral
harassment threshold where there is available information to support
methodologies that better reflect the variation in individual
responses. However, the current threshold allows for an appropriate,
and often conservative, enumeration of predicted takes by Level B
harassment, which support robust negligible impact and small numbers
analyses.
Comment: Nowacek et al. stated that use of the 160-dB threshold
would be specifically problematic for beaked whales, as these species
demonstrate behavioral response at levels below 160 dB rms and occupy
certain areas of the specific geographic region in high densities.
Response: Please see our previous comment response regarding use of
the 160-dB threshold for behavioral harassment. With regard to the
expected significance of takes by harassment specifically for beaked
whales, we acknowledge that beaked whales are documented as being a
particularly behaviorally sensitive species in response to noise
exposure. This information is considered in our negligible impact
analyses (``Negligible Impact Analyses and Determinations'') and
informed our evaluation of the mitigation necessary to satisfy the
least practicable adverse impact standard (``Mitigation''). We require
implementation of three year-round closures of submarine canyon areas
expected to provide important habitat for beaked whales, a seasonal
closure of the area off of Cape Hatteras cited by the commenters, and
have required expanded shutdown requirements for beaked whales.
Additionally, regarding the specific levels at which they are
behaviorally harassed by exposure to noise from airguns, we note that
there are no data on beaked whale responses to airgun noise, and their
hearing sensitivity in the frequency range of signals produced by
airguns is notably lower than their sensitivity in the frequency range
of the sonar sources for which data is available indicating that they
have responded at lower levels (in other words, noise from an airgun
must be louder than a sonar pulse for them to hear it as the same
level).
Comment: NRDC and others stated that if NMFS does not revise
existing behavioral harassment thresholds, it should use the acoustic
threshold for continuous noise (i.e., 120 dB rms) rather than the
threshold for intermittent sound sources (i.e., 160 dB rms). NRDC
contends that, as a result of reverberation and multipath arrivals, the
impulsive signal produced by airguns is more similar to a continuous
noise at greater distances from the source and,
[[Page 63287]]
therefore, use of the 120-dB ``continuous'' noise threshold is more
appropriate than the 160-dB threshold for intermittent sound sources.
Response: NMFS acknowledges that as airgun shots travel through the
environment, pulse duration increases because of reverberation and
multipath propagation. However, we disagree that the 120-dB rms
threshold for continuous noise--which was based on behavioral responses
of baleen whales to drilling (Malme et al., 1984; Richardson et al.,
1990)--is more appropriate than the intermittent noise threshold of
160-dB rms for evaluating potential behavioral harassment resulting
from airgun noise. The 160-dB threshold was derived from data for
mother-calf pairs of migrating gray whales (Malme et al., 1983, 1984)
and bowhead whales (Richardson et al., 1985, 1986) behaviorally
responding when exposed specifically to noise from airguns. The
Richardson et al. (1985, 1986) studies included controlled approaches
with a full-scale airgun array firing at 7.5 km from the animals. Thus,
behavioral responses observed in these studies account for changes in
the pulse duration associated with propagation.
In addition, there is a prevalent misconception in comments from
NRDC and others regarding Level B harassment, as defined by the MMPA.
NRDC cites multiple observations of behavioral reactions or of changes
in vocal behavior in making statements supporting their overall
recommendation that behavioral harassment thresholds be lower. However,
these observations do not necessarily constitute evidence of disruption
of behavioral patterns (Level B harassment) rather than simple
reactions to often distant noise, which may provoke a reaction when
discernable above ambient noise levels.
For example, changes in mysticete vocalization associated with
exposure to airgun surveys within migratory and non-migratory contexts
have been observed (e.g., Castellote et al., 2012; Blackwell et al.,
2013; Cerchio et al., 2014). The potential for these changes to occur
over large spatial scales is not surprising for species with large
communication spaces, like mysticetes (e.g., Clark et al., 2009),
although not every change in a vocalization would necessarily rise to
the level of a take.
Comment: NRDC claims that NMFS misapplies the MMPA's statutory
definition of harassment by adopting a probability standard other than
``potential'' in setting thresholds for auditory injury, stating that a
take estimate based on ``potential'' should either count take from the
lowest exposure level at which hearing loss can occur or establish a
probability function that accounts for variability in the acoustic
sensitivity of individual marine mammals. Instead, NRDC states that
NMFS derived auditory injury thresholds from average exposure levels at
which tested marine mammals experience hearing loss, which discounts
instances of hearing loss at lower levels of exposure. The comment goes
on to state that for purposes of take estimation, thresholds based on
mean or median values will lead to roughly half of an exposed cohort
experiencing the impacts that the threshold is designed to avoid, at
levels that are considered ``safe,'' therefore resulting in substantial
underestimates of auditory injury. NRDC makes similar statements with
regard to the 160-dB threshold for Level B harassment.
Response: The technical guidance's (NMFS, 2018) onset thresholds
for temporary threshold shift (TTS) for non-impulsive sounds encompass
more than 90 percent of available TTS data (i.e., for mid-frequency
cetaceans, only two data points are below the onset threshold, with
maximum point only 2 dB below), and in some situations 100 percent of
TTS data (e.g., high-frequency cetaceans; although this group is data-
limited). Thus, the technical guidance thresholds provide realistic
predictions, based on currently available data, of noise-induced
hearing loss in marine mammals. For impulsive sounds, data are limited
to two studies, and NMFS directly adopted the TTS onset levels from
these two studies for the applicable hearing groups.
Our Federal Register notice announcing the availability of the
original technical guidance (81 FR 51694; August 4, 2016; NMFS, 2016),
indicated that onset of auditory injury (PTS) equates to Level A
harassment under the MMPA. We explained in that notice that because the
acoustic thresholds for PTS conservatively predict the onset of PTS,
they are inclusive of the ``potential'' language contained in the
definition of Level A harassment. See 81 FR 51697, 51721.
Regarding Level B harassment, based on the language and structure
of the definition of Level B harassment, we interpret the concept of
``potential to disturb'' as embedded in the assessment of the
behavioral response that results from an act of pursuit, torment, or
annoyance (collectively referred to hereafter as an ``annoyance''). The
definition refers to a ``potential to disturb'' by causing disruption
of behavioral patterns. Thus, an analysis that indicates a disruption
in behavioral patterns establishes the ``potential to disturb.'' A
separate analysis of ``potential to disturb'' is not needed. In the
context of an authorization such as this, our analysis is forward-
looking. The inquiry is whether we would reasonably expect a disruption
of behavioral patterns; if so, we would conclude a potential to disturb
and therefore expect Level B harassment. We addressed NRDC's concerns
regarding the scientific support for the Level B harassment threshold
in a previous comment response.
Comment: The Center for Regulatory Effectiveness (CRE) does not
agree with NMFS's use of the technical acoustic guidance (NMFS, 2016,
2018) for purposes of evaluating potential auditory injury. CRE claims
that (1) NMFS's use of the guidance conflicts with Executive Order
13795 (``Implementing an America-First Offshore Energy Strategy''); (2)
the guidance violates the Office of Management and Budget's (OMB) Peer
Review Bulletin and Guidance Document Bulletin and implementing
Memoranda; (3) violates Information Quality Act (IQA) guidelines; and
(4) violates Executive Orders 12866 (``Regulatory Planning and
Review'') and 13771 (``Reducing Regulation and Controlling Regulatory
Costs''). Regarding the IQA, CRE states that NMFS does not have an OMB-
approved Information Collection Request (ICR) associated with the
guidance, and is therefore violating the IQA. The CRE also claims that
NMFS's use of the guidance violates the MMPA requirement that all
mitigation requirements be practicable, as the guidance supposedly
requires monitoring and reporting requirements and other mitigation
requirements that are impossible to comply with.
Response: NMFS disagrees that use of the technical guidance results
in any of the claims listed by CRE. First, the use of the technical
guidance does not conflict with Executive Order 13795. Section 10 of
the Executive Order called for a review of the technical guidance
(NMFS, 2016) as follows: ``The Secretary of Commerce shall review for
consistency with the policy set forth in Section 2 of this order and,
after consultation with the appropriate Federal agencies, take all
steps permitted by law to rescind or revise that guidance, if
appropriate.'' To assist the Secretary in the review of the technical
guidance, NMFS solicited public comment via a 45-day public comment
period (82 FR 24950; May 31, 2017) and hosted an interagency
consultation meeting with representatives from ten federal agencies
(September 25, 2017). NMFS
[[Page 63288]]
provided a summary of comments and recommendations received during this
review to the Secretary, and per the Secretary's approval, issued a
revised version of the technical guidance in June 2018 (83 FR 28824;
NMFS, 2018).
Second, NMFS did comply with the OMB Peer Review Bulletin and IQA
Guidelines in development of the technical guidance. The technical
guidance was classified as a Highly Influential Scientific Assessment
and, as such, underwent three independent peer reviews, at three
different stages in its development, including a follow-up to one of
the peer reviews, prior to its dissemination by NMFS. In addition,
there were three separate public comment periods. Responses to public
comments were provided in a previous Federal Register notice (81 FR
51694; August 4, 2016). Detailed information on the peer reviews and
public comment periods conducted during development of the guidance are
included as an appendix to the guidance, and are detailed online at:
www.cio.noaa.gov/services_programs/prplans/ID43.html.
Furthermore, the technical guidance is not significant for purposes
of Executive Orders 12866 or 13771 or OMB's Bulletin entitled, ``Agency
Good Guidance Practices'' for significant guidance documents. 72 FR
3432 (January 25, 2007). Nevertheless, the technical guidance follows
the practices and includes disclaimer language suggested by the OMB
Bulletin to communicate effectively to the public about the legal
effect of the guidance. Finally, with regard to the claim that NMFS's
use of the technical guidance violates the MMPA requirement that all
mitigation requirements be practicable, as the guidance supposedly
requires monitoring and reporting requirements and other mitigation
requirements that are impossible to comply with, we reiterate that
mitigation and monitoring requirements associated with an MMPA
authorization or ESA consultation or permit are independent management
decisions made in accordance with statutory and regulatory standards in
the context of a proposed activity and comprehensive effects analysis
and are beyond the scope of the technical guidance. The technical
guidance does not mandate mitigation or monitoring. Finally, there is
no collection of information requirement associated with the technical
guidance, so no ICR is required.
Comment: Several groups raised concerns regarding use of the
technical acoustic guidance (NMFS, 2016, 2018), claiming that the
guidance is not based on the best available science and underestimates
potential auditory injury. NRDC specifically cited many supposed issues
with the guidance, including adoption of ``erroneous'' models, broad
extrapolation from a small number of individuals, and disregarding
``non-linear accumulation of uncertainty.'' NRDC suggests that NMFS
retain the historical 180-dB rms Level A harassment threshold as a
``conservative upper bound'' or conduct a ``sensitivity analysis'' to
``understand the potential magnitude'' of the supposed errors. Oceana
stated that NMFS should not make a decision about the proposed IHAs
while the technical guidance is under review.
Response: The original 2016 technical guidance and revised 2018
guidance is a compilation, interpretation, and synthesis of the
scientific literature that provides the best available information
regarding the effects of anthropogenic sound on marine mammals'
hearing. The technical guidance was classified as a Highly Influential
Scientific Assessment and, as such, underwent three independent peer
reviews, at three different stages in its development, including a
follow-up to one of the peer reviews, prior to its dissemination by
NMFS. In addition, there were three separate public comment periods,
during which time we received and responded to similar comments on the
guidance (81 FR 51694), and more recent public and interagency review
under Executive Order 13795. While new information may help to improve
the guidance in the future, and NMFS will review the available
literature to determine when revisions are appropriate, the final
guidance reflects the best available science and all information
received through peer review and public comment. Given the systematic
development of the guidance, which was also reviewed multiple times by
both independent peer reviewers and the public, NRDC's use of the
phrase ``arbitrary and capricious'' is unreasonable.
The guidance updates the historical 180-dB rms injury threshold,
which was based on professional judgement (i.e., no data were available
on the effects of noise on marine mammal hearing at the time this
original threshold was derived). NMFS does not believe the use of the
technical guidance provides erroneous results. The 180-dB rms threshold
is plainly outdated, as the best available science indicates that rms
SPL is not even an appropriate metric by which to gauge potential
auditory injury (whereas the scientific debate regarding behavioral
harassment thresholds is not about the proper metric but rather the
proper level or levels and how these may vary in different contexts).
NRDC's advice to return to use of the 180-dB threshold is inconsistent
with its criticism of the 160-dB rms criterion for Level B harassment.
However, as we said in responding to comments criticizing the Level B
harassment criterion, development of an updated threshold(s) is
complicated by the myriad contextual and other factors that must be
considered and evaluated in reaching appropriate updated criteria. See
our response to comment on the Level B harassment threshold.
Sound Field Modeling
Comment: The MMC noted differences in the estimated Level B
harassment radii provided in ION and Spectrum's applications, noting
that since the largest discrepancies were observed at shallow water
sites, it is likely that geoacoustic properties were responsible.
Although both ION and Spectrum used sediment data from cores collected
during the Ocean Drilling Program, the data was based on samples from
different sites and potentially different assumptions as to sediment
attenuation. The MMC provided related recommendations: (1) NMFS should
determine whether ION's or Spectrum's estimated zones are the most
appropriate and require that both companies use the same set of zones;
(2) NMFS should require each of the five companies to conduct sound
source verification (SSV) in waters less than 100 m and use that data
to inform and adjust the extent of Level B harassment zones as
necessary; and (3) NMFS should determine the appropriate baseline
geoacoustic model for the region in concert with BOEM, ION, and
Spectrum, and then require this in future IHAs for similar activities
in the region.
Response: NMFS appreciates the MMC's attention to this matter, but
disagrees that it is necessarily appropriate to require use of the same
data or approaches to modeling sound fields when there is not clearly a
``most appropriate'' approach. Sound field modeling for both ION and
Spectrum was conducted by experts in the field. We appropriately
approved both applicants' applications as adequate and complete,
determining that both used appropriate data inputs and acceptable
modeling approaches. Subsequently, both applications were made
available for public review in order to better inform NMFS's
preparation of proposed IHAs; no such concerns were raised.
Importantly, we recognize that there is no model or approach that is
always the most appropriate and that there may be multiple approaches
that may be
[[Page 63289]]
considered acceptable. Having determined that both applicants used
appropriate data and acceptable modeling approaches, it would be
inappropriate to require one to change their approach to conform to the
other because of differences in the results. Given our confidence in
the data inputs and modeling approaches used, we find that a
requirement to conduct SSV studies is not warranted, despite
discrepancies in modeling results. As is appropriate, NMFS would
consider the appropriateness of data inputs and modeling approaches for
any future applications but, in keeping with our response here, will
not necessarily enforce use of one dataset or modeling approach when
others may be considered as equally representative of the best
available scientific data and techniques.
Comment: One individual suggested that, because the representative
airgun array used in BOEM's sound field modeling was characterized as
having a source level lower than that of arrays planned for use by the
applicants, use of BOEM's sound field modeling could lead to an
underestimate of takes.
Response: Numerous factors combine in the sound field modeling
provided by BOEM to result ultimately in estimates of sound fields at
different locations. BOEM's modeling was performed to be reasonably
representative of the types of sources that would be used in future
surveys, recognizing that actual sources may vary somewhat from what
was considered in the sound field modeling. We disagree that these
minor differences would have meaningful impacts on the ultimate result
of the exposure estimation process, and find that the modeling provided
by BOEM was reasonably representative of what would occur during actual
surveys and, therefore, acceptable to use for informing the take
estimates for these surveys.
Comment: One individual stated that NMFS does not fully consider
the implications of different weather phenomena in acoustic
propagation, and that in failing to account for variations in ocean and
weather conditions, the average estimates of propagation and take are
biased downward. The same individual also claimed that NMFS did not
adequately consider ocean floor sediment composition in modeling
expected sound fields, and states again that this would likely result
in higher numbers of take.
Response: While NMFS acknowledges that discrete weather phenomena
could result in propagation being more or less efficient than
anticipated under a seasonal average scenario (i.e., one element of
propagation modeling is the use of sound velocity profiles that are
season-specific within the specific geographic region), the commenter
provides no basis for concluding that such phenomena would lead overall
to the estimated takes being biased downward. Further, the sound field
modeling approaches taken by the applicants (and in BOEM's PEIS) follow
state-of-science approaches and are reasonable when considering the
need to model propagation year-round and over a wide geographic area.
The commenter provides no specific recommendation for how the
suggestion should be accomplished. With regard to sediment composition,
the applicants' sound field modeling considered sediment
characteristics at 15 representative modeling sites throughout the
region, and the commenter does not provide any evidence to back the
claim that variability in actual sediment composition would result in
bias to take estimates in a particular direction or provide any
specific recommendation to remedy the perceived flaw.
Comment: Ocean Conservation Research (OCR) noted that NMFS did not
consider a secondary transmission path in the mixed layer above the
marine thermocline that behaves as a surface duct, stating that, while
the propagation in this transmission path is dependent on the
wavelength of the source, the angle of incidence, the depth of the
mixed layer, and the surface conditions, the attenuation
characteristics are more consistent with the cylindrical spreading
model. OCR goes on to claim that, assuming cylindrical propagation of
surface ducted noise, typical airgun noise would require 13 km to
attenuate to a received level of 180 dB rms.
Response: Although OCR is correct to point out that the mechanism
of sound propagation is complex in the ocean environment, with the
potential formation of a surface duct as a result of the mixed layer
above the permanent thermocline, the conclusion derived by OCR that
typical airgun noise would require 13 km to attenuate to a received
level of 180 dB rms is unsupported.
First, oceanographic conditions in the mid-Atlantic region do not
support a persistent surface duct, which usually occurs after a storm
or consistently cool and windy weather. A reduction of surface wind
velocity and the warming of the surface water will quickly break down a
surface duct and cause the downward refraction of a shallow source
(e.g., source from an airgun array) due to a negative sound velocity
profile above the thermocline.
Second, as stated above, the formation of a surface duct requires
strong wind gusts and a high sea state, which are not ideal conditions
for conducting a seismic survey given the need to tow a large array of
airguns and long streamers. Thus, even if a surface duct is formed, it
is very unlikely that a seismic survey would continue under such
conditions.
Third--as OCR correctly pointed out--sound propagation in a surface
duct is dependent on the wavelength of the source, the angle of
incidence, the depth of the mixed layer, and the surface conditions.
Among these parameters, the depth of the mixed layer is typically
determined by the wind speed and sea state. While relatively low wind
speed may support a weak, shallow surface duct, such a duct cannot
support propagation of airgun sound, which is predominantly low-
frequency. Jensen et al. (2011) provide the following equation that
determines the cutoff frequency (frequency below which sound will not
propagate) given the depth of an isothermal surface layer:
[GRAPHIC] [TIFF OMITTED] TN07DE18.001
where f0 is the cutoff frequency in Hz and D is the depth in
meters of an isothermal surface layer. As an example, for a cutoff
frequency to be around 100 Hz, the surface duct needs to be at least
150 m deep. In general, shallow ducts (D <50 m) are more common, but
they are only effective waveguides for frequencies above 530 Hz, which
also suffer high scattering loss due to the rough sea surface under
these weather conditions.
Finally, most acoustic rays from an airgun array are emitted at
very steep angles to be contained within the surface duct waveguide.
For these reasons, we do not believe surface ducts in the mid-
Atlantic region, if they exist, would contribute noticeably to
propagation for sound emitted from airguns.
Comment: NRDC stated that NMFS used unrealistic and non-
conservative assumptions about spreading loss, bottom composition, and
reverberation in its propagation analysis and claimed that the analysis
does not represent the best available science. NRDC stated that, for
propagation loss, NMFS incorrectly assumed that normal propagation
conditions would apply, such as not accounting for surface ducting (and
BOEM only assumed moderate surface ducting in 3 of 21 modeled areas).
Furthermore, NRDC stated that low-
[[Page 63290]]
frequency propagation along the seabed can spread in a planar manner,
and can propagate with more efficiency than indicated by cylindrical
propagation. Finally, NRDC asserted that NMFS cannot accept the
assumptions in three applications (CGG, TGS, and WesternGeco) that
proposed surveys will cover areas with soft or sandy bottoms. NRDC
claims that NOAA's own models indicate that there is a likelihood of
coral bottom habitat in the survey area, and many hard-bottom habitat
areas were not modeled by BOEM and consequently incorporated by NMFS.
Response: Regarding sound propagation in a surface duct, please
refer to the above response to a similar comment from OCR. As stated
earlier, oceanographic conditions in the mid-Atlantic region do not
support a persistent surface duct, particularly for low-frequency sound
propagation. Therefore, the modeling of a moderate surface duct for
airgun noise propagation is a conservative measure. Also as stated
earlier, frequency and launch angle of the source play a major role in
surface ducting. This information is clearly stated by D'Spain et al.
(2006) with regard to the 2000 beaked whale stranding in the Bahamas,
i.e., that the surface duct ``. . . effectively traps mid to high
frequency sound radiated by acoustic sources within the duct, such as
surface ship sonars . . .'' and that ``[a]t low frequencies, the sound
is no longer effectively trapped by the duct because the acoustic
wavelength. . . . is too large in comparison to the duct thickness.''
NRDC's statement that ``low-frequency propagation along the seabed
can spread in a planar manner . . . can propagate with significantly
greater efficiency than cylindrical propagation would indicate'' is
incorrect. Any acoustic wave can be approximated for plane wave
propagation at sufficiently far range (R) for a region (W) such that W
<= ([lambda]R)1/2, where [lambda] is the wavelength. This
plane wave approximation has no bearing on the efficiency of sound
propagation.
Finally, substrate types for propagation modeling are based on
grain size, porosity, and shear velocity, etc., and ``coral bottom'' is
not one of them. In fact, the roughness of the coral habitat would
cause severe bottom loss due to scattering. Based on published
literature, bottom types of the region are mostly composed of sand
(e.g., Stiles et al., 2007; Kaplan, 2011). Therefore, the use of sand
and clay for propagation modeling is appropriate. The acoustic modeling
provided by BOEM (2014a) appropriately and reasonably accounts for
variability in bottom composition throughout the planned survey area.
Comment: Some groups noted that the different approaches taken to
acoustic modeling make it difficult to compare takes. Specifically,
TGS, CGG, and Western relied on the acoustic modeling provided in
BOEM's PEIS, while ION and Spectrum performed their own modeling. In
addition, Spectrum and ION used a restricted suite of sound velocity
profiles, matching the seasons when they intend to conduct their
planned surveys. The comment letter from Nowacek et al. adds an
assertion that this difficulty in comparing takes is problematic when
NMFS is trying to assess whether the activities impact only small
numbers or cause negligible impacts, and state that they ``can find no
evidence in the Notice that NMFS took account of these significant
problems when attempting to evaluate the impacts of the IHAs.''
Response: As stated in a previous response to an MMC comment, NMFS
disagrees that the different approaches taken to sound field modeling
constitute a problem at all, much less a significant one. BOEM's PEIS
provides a sound analysis of expected sound fields in a variety of
propagation conditions, including water depth, bottom type, and season,
for a representative airgun array. ION and Spectrum conducted similar
sound field modeling, but with the added advantage of modeling the
specific array planned for use and limiting use of sound velocity
profiles to the time period when the survey is planned to occur. No
commenter provided any rational basis for disputing that these methods
are appropriate or that they used the best available information and
modeling processes. Regardless of differences in the sound field
modeling processes, one would not expect that the take estimates are
directly comparable, precisely because the surveys are planned for
different locations, using different sound sources, and, for some
companies, operating at different times of year. We disagree the
various modeling approaches cause some problem for conducting
appropriate negligible impact and/or small numbers analyses; both of
these findings are appropriately made in consideration of a given
specified activity. Therefore, comparison of the take numbers across
IHAs is not a relevant consideration. We disagree that differences in
approaches across the applications are arbitrary. On the contrary, we
carefully evaluated each applicant's approaches to take estimation and,
while they are indeed different in some respects, each applicant uses
accepted approaches. Unlike NRDC, we recognize that there is no model
or approach that is always the most appropriate and that there may be
multiple approaches that may be considered acceptable. Far from
``parroting'' the applicants' assessments, as NRDC implies, NMFS made
substantial changes where necessary, including complete revision of
North Atlantic right whale take estimates for all applicants, revision
of take estimates for all species using the best available density data
(i.e., Roberts et al., 2016) for ION and Spectrum, and revised
assessment of potential Level A harassment for all applicants. NMFS
strongly disagrees that ``grossly inconsistent'' data or methods were
used for any applicant in the analyses described herein.
Comment: One individual noted that it is not apparent how NMFS
accounted for high-frequency sounds, which has implications for
potential takes by Level A harassment for species that hear better at
higher frequencies. The commenter wrote that airguns produce pulses
with most energy at low frequencies (around 10 Hz), but that these
pulses contain significant energy at frequencies up to more than 100
kHz, claiming that high-frequency hearing specialists can be affected
at distances of 70 km or more. The commenter cited Bain and Williams
(2006) in support of the latter claim.
Response: In considering the potential impacts of higher-frequency
components of airgun noise on marine mammal hearing, one needs to
account for energy associated with these higher frequencies and
determine what energy is truly ``significant.'' Tolstoy et al. (2009)
conducted empirical measurements, demonstrating that sound levels
(i.e., one-third-octave and spectral density) associated with airguns
were at least 20 dB lower at 1 kHz compared to higher levels associated
with lower frequencies (below 300 Hz). These levels were even lower at
higher frequencies beyond 1 kHz. Thus, even though high-frequency
cetaceans may be more susceptible to noise-induced hearing loss at
higher frequencies, it does not mean that a source produces a
sufficiently loud sound at these higher frequencies to induce a PTS
(i.e., auditory injury). For example, Bain and Williams (2006)
indicated ``airguns produced energy above ambient levels at all
frequencies up to 100 kHz (the highest frequency measured), although
the peak frequency was quite low.'' However, a finding that airgun
signals contain energy ``above ambient'' and are detectable at
frequencies up to 100 kHz does not mean that these levels are high
enough to result in auditory injury. The commenter does not describe
what is
[[Page 63291]]
meant by ``significant'' energy, but there is no information to suggest
that these higher-frequency noise components are sufficient to cause
auditory injury at ranges beyond those described in Table 5.
Furthermore, Bain and Williams (2006) focus on behavioral responses
of marine mammals to airgun surveys, rather than on potential impacts
on hearing. Harbor porpoises, while considered a high-frequency
cetacean in terms of hearing, are also often categorized as a
particularly sensitive species behaviorally (i.e., consistently
responds at a lower received level than other species; Southall et al.,
2007). We agree that harbor porpoises are more likely to avoid loud
sound sources, such as airgun arrays, at greater distances. However,
this means that these species are even less likely to incur some degree
of threshold shift.
Marine Mammal Densities
Comment: The MMC recommended that NMFS require TGS and Western to
use the Roberts et al. (2016) model, rather than the approach described
herein (see ``Estimated Take''). MMC describes several perceived
problems with the approach taken by TGS and Western, including that
they do not adequately account for availability and detection biases,
and that their approach does not use the same habitat-based approach to
predicting density. Overall, they state that it does not make sense for
applicants to use different density estimates for the same area.
Response: Please see ``Estimated Take'' for a full description of
take estimation methodologies used by TGS and Western. First, we note
that the applicants did carefully consider the Roberts et al. data in
addition to other available sources of data. In fact, these two
applicants did use the Roberts et al. data for a group of nine species,
while devising an alternate methodology for a separate group of seven
species that did not meet a specific threshold for sightings data
recommended by Buckland et al. (2001). Further, these applicants did
account for bias, correcting densities using general g(0) values for
aerial and vessel surveys for each species as published in the
literature.
As stated below and in our Notice of Proposed IHAs, we determined
that their alternative approach (for seven species or species groups)
is acceptable. We recognize that there is no model or approach that is
always the most appropriate and that there may be multiple approaches
that may be considered acceptable. The alternative approach used for
seven species actually uses the most recent data, and does so in a way
that conforms with recommended methods for deriving density values from
sightings data. We do not believe that one or the other approach is
non-representative of the best available science and methodologies.
Comment: NRDC criticized NMFS's use of the Roberts et al. (2016)
model outputs for purposes of deriving abundance estimates, as used in
NMFS's small numbers analyses. NRDC states that we should use the NMFS
Stock Assessment Report (SAR) abundance estimates for this purpose,
while allowing that model-predicted abundance estimates may be used for
``data-deficient'' stocks. NRDC implies that use of model-predicted
abundances would overestimate actual abundances, apparently based on
the fact that the density models are informed by many years of data
rather than only the most recent year of data. Where model-predicted
abundance estimates are used, NRDC recommends that we adjust the
averaged model outputs to the lower bound of the standard deviation
estimated by the model for each grid cell.
Response: The approach recommended by NRDC is plainly
inappropriate. Comparing take estimates generated through use of the
outputs of a density model to an unrelated abundance estimate provides
a meaningless comparison. As explained in our Notice of Proposed IHAs,
in most cases we compare the take estimates generated through use of
the density outputs to the abundance predicted through use of the model
precisely to provide a meaningful comparison of predicted takes to
predicted population. To illustrate this, we provide the extreme
example of the Gulf of Mexico stock of Clymene dolphin. NMFS's three
most recent SAR abundance estimates for this stock have fluctuated
between 129 and 17,355 animals, i.e., varying by a maximum factor of
more than 100. For most species, such fluctuations across these
``snapshot'' abundance estimates (i.e., that are based on only the most
recent year of survey data) reflect interannual variations in dynamic
oceanographic characteristics that influence whether animals will be
seen when surveying in predetermined locations, rather than any true
increase or decline in population abundance. In fact, NMFS's SARs
typically caution that trends should not be inferred from multiple such
estimates, that differences in temporal abundance estimates are
difficult to interpret without an understanding of range-wide stock
abundance, and that temporal shifts in abundance or distribution cannot
be effectively detected by surveys that only cover portions of a
stock's range (i.e., U.S. waters). The corresponding density model for
Gulf of Mexico Clymene dolphins predicts a mean abundance of 11,000
dolphins. Therefore, in this example, NRDC would have us compare takes
predicted by a model in which 11,000 dolphins are assumed to exist to
the most recent (and clearly inaccurate) abundance estimate of 129
dolphins. Our goal in assessing predicted takes is to generate a
meaningful comparison, which is accomplished in most cases through use
of the model-predicted abundance.
SAR abundance estimates have other issues that compromise their use
in creating meaningful comparisons here. As in the example above, use
of multiple years of data in developing an abundance estimate minimizes
the influence of interannual variation in over- or underestimating
actual abundance. Further, SAR abundance estimates are typically
underestimates of actual abundance because they do not account for
availability bias due to submerged animals--in contrast, Roberts et al.
(2016) do account for availability bias and perception bias on the
probability of sighting an animal--and because they often do not
provide adequate coverage of a stock's range. The SAR for the Canadian
East Coast stock of minke whales provides an instructive example of the
latter. In the 2015 SARs, NMFS presented a best abundance estimate of
20,741 minke whales, reflecting data that provided adequate (but not
complete) coverage of the stock's range. In the 2016 SARs, NMFS claims
an abundance estimate of 2,591 whales for this same stock (albeit with
caveats) simply because the survey data covering the Canadian portion
of the range was no longer included in determining the best abundance
estimate. We assume that again, based on this comment, NRDC would have
us compare the minke whale take estimates to this plainly incomplete
abundance estimate.
NRDC appears to claim that the SARs are an appropriate
representation of ``actual'' abundance, whereas the Roberts et al.
(2016) predictions are not. NRDC also appears to claim, without
substantiation, that an abundance estimate derived from multiple years
of data would typically overestimate actual abundance. However, these
estimates are not directly comparable--not because one represents a
``snapshot,'' while one represents multiple years of data, but because
one does not correct for one or more known biases against the
probability of observing animals
[[Page 63292]]
during survey effort, while the other does. Because of this important
caveat, NMFS's SAR abundance estimates should not be considered
``actual'' abundance more than any other accepted estimate. Therefore,
when multiple estimates of a stock's abundance are available, they
should be evaluated based on quality, e.g., does the estimate account
for relevant biases, does it best cover the stock's range, does it
minimize the effect of interannual variability, and, importantly,
should provide a meaningful comparison. In summary, NRDC's comment
reflects an inaccurate interpretation of the available information, and
NMFS strongly disagrees with the recommended approach.
Take Estimates
Comment: The Associations (representing oil and gas industry
interests) state that ``NMFS substantially overestimates the number of
incidental takes predicted to result'' from the specified activities.
The comment goes on to discuss the ``biased modeling that is
intentionally designed to overestimate take'' provided in BOEM's 2014
PEIS. Other industry commenters repeat these points verbatim.
Response: The Associations' statement that NMFS has substantially
overestimated takes is incorrect. First, in large part the take
estimates are those presented by the applicants (although in some cases
NMFS has made changes to the presented estimates in accordance with the
best available information). Second, two applicants conducted their own
independent sound field modeling, which NMFS accepted. In fact, BOEM
and these two applicants followed best practices and used the best
available information in conducting state-of-the-science sound field
modeling. The Associations' complaints include no substantive
recommendations for improvement.
NMFS participated in development of the acoustic modeling through
its status as a cooperating agency in development of BOEM's PEIS. We
strongly disagree with the Associations' characterization of the
modeling conducted by BOEM and with the BOEM statements cited by the
Associations. While the modeling required that a number of assumptions
and choices be made by subject matter experts, some of these are
purposely conservative to minimize the likelihood of underestimating
the potential impacts on marine mammals represented by a specified
level of survey effort. The modeling effort incorporated representative
sound sources and projected survey scenarios (both based on the best
available information obtained by BOEM), physical and geological
oceanographic parameters at multiple locations within U.S. waters of
the mid- and south Atlantic and during different seasons, the best
available information regarding marine mammal distribution and density,
and available information regarding known behavioral patterns of the
affected species. Current scientific information and state-of-the-art
acoustic propagation and animal movement modeling were used to
reasonably estimate potential exposures to noise. NMFS's position is
that the results of the modeling effort represent a conservative but
reasonable best estimate. These comments provide no reasonable
justification as to why the modeling results in overestimates of take,
instead seemingly relying on the mistaken notion that real-time
mitigation would somehow reduce actual levels of acoustic exposure, and
we disagree that ``each of the inputs is purposely developed to be
conservative''--indeed, neither the Associations nor BOEM provide any
support for the latter statement. Although it may be correct that
conservativeness accumulates throughout the analysis, the Associations
do not adequately describe the nature of conservativeness associated
with model inputs or to what degree (either quantitatively or
qualitatively) such conservativeness ``accumulates.''
Comment: One individual stated that NMFS should consider how
``animal behavioral response can condition exposure,'' noting that
behavioral responses may result in effects to the potential amount and
intensity of take. We believe the commenter is suggesting that the way
any specific animal moves through the water column in initial response
to the sound can change the manner in which they are subsequently
further exposed to the sound.
Response: The commenter seemingly indicated that some species
should be expected to dive downwards rather than exhibit lateral
avoidance. While we agree that this may occur, we do not agree that
this would result in an increase in intensity of take--and such an
occurrence could not by definition result in an increase in the
absolute amount of take, as the animal in question would already be
considered ``taken.'' Given relative motion of the vessel and the
animal, there is no evidence to support that avoidance of the noise
through downward, rather than lateral, movement would result in a
meaningful increase in the duration of exposure, as implied by the
commenter.
Comment: The Associations stated that it is unclear whether the
take estimates include repeated exposures and that, if so, the
estimates do not identify the number of repeated exposures, instead
presenting a total number of estimated exposures by species. The
Associations state that NMFS must perform additional analysis to
identify the actual number of individual marine mammals that may be
incidentally taken.
Response: The take estimates presented in our Notice of Proposed
IHAs, and those shown in Table 6 of this notice, represent total
estimated instances of exposure. We agree with the Associations that an
understanding of the numbers of individuals affected by the total
estimated instances of exposure is relevant, both for the small numbers
analysis (a small numbers analysis is appropriately made on the basis
of individuals taken rather than total takes, when such information is
available) but also for assessing potential population-level impacts in
a negligible impact analysis. We also agree that this information is
relevant to these analyses and important to use, when available. In
fact, one applicant (TGS) provided an analysis of individuals exposed;
following review of public comments and re-evaluation of TGS's
application, we considered this information in our small numbers
analysis for TGS. However, without such information, an assumption that
the total estimated takes represent takes of different individuals is
acceptable in that it represents a conservative estimate of the total
number of individuals taken made in the absence of sufficient
information to differentiate between individuals exposed and instances
of exposure, and is also generally a reasonable approach given the
large, dispersed spatial scales over which the surveys operate. The
MMPA does not require that NMFS undertake any such analysis and, in
fact, sufficient information is not typically available to support such
an analysis.
Comment: NRDC states that masking results in take of marine
mammals, and that NMFS must account for this in its take estimates.
Response: We addressed our consideration of masking in greater
detail in a previous response. We acknowledge that masking may impact
marine mammals, particularly baleen whales, and particularly when
considered in the context of the full suite of regulated and
unregulated anthropogenic sound contributions overlaying an animal's
acoustic habitat. However, we do not agree that masking effects from
the incremental noise contributions of individual activities or sound
sources necessarily, or typically,
[[Page 63293]]
rise to the level of a take. While it is possible that masking from a
particular activity may be so intense as to result in take, we have no
information suggesting that masking of such intensity and duration
would occur as a result of the specified activities. As described in
our previous comment response, potential effects of a specified
activity must be accounted for in a negligible impact analysis, but not
all responses or effects result in take nor are those that do always
readily quantified. In this case, while masking is considered in the
analysis, we do not believe it will rise to the level of take in the
vast majority of exposures. However, specifically in the case of these
five surveys, in the unanticipated event that any small number of
masking incidents did rise to the level of a take, we would expect them
to be accounted for in the quantified exposures above 160 dB. Given the
short duration of expected noise exposures, any take by masking in the
case of these surveys would be most likely to be incurred by
individuals either exposed briefly to notably higher levels or those
that are generally in the wider vicinity of the source for
comparatively longer times. Both of these situations would be captured
in the enumeration of takes by Level B harassment, which is based on
exposure at or above 160 dB, which also means the individual
necessarily spent a comparatively longer time in the adjacent area
ensonified below 160 dB, but in which masking might occur if the
exposure was notably longer.
Comment: NRDC, the MMC, and others state that NMFS's Level A
harassment exposure analysis contains potentially significant errors.
The MMC recommends that NMFS (1) provide company-specific Level A
harassment zones for each functional hearing group, and (2) re-estimate
the numbers of Level A harassment. NRDC states that, by relying on
BOEM's 2014 PEIS, NMFS did not use the best available science, e.g.,
use of earlier density data (DoN, 2007) rather than Roberts et al.
(2016). NRDC goes on to cite as an additional flaw of the analysis that
``NMFS assumes that auditory take estimates for high-frequency
cetaceans depend on the exposure of those species to single seismic
shots . . . even though the weighted auditory injury zone for high-
frequency cetaceans extends as far as 1.5 kilometers [ . . . . ] The
size of the injury zone suggests that NMFS' assumption about high-
frequency cetaceans is incorrect, and that the agency should calculate
auditory injury by applying both the peak-pressure threshold and a
metric that accounts for exposure to multiple shots (e.g., the
cumulative sound energy thresholds included in NMFS' guidance).''
Response: As described in ``Estimated Take,'' NMFS revised the
approach to assessing potential for auditory injury, and associated
authorization of take by Level A harassment. NMFS disagrees that the
prior approach for the proposed IHAs contained ``significant errors.''
As stated in our Notice of Proposed IHAs, we used the information
available to us and made reasonable corrections to account for
applicant-specific information. However, following review of public
comments, we determined it appropriate to re-evaluate the analysis and
subsequently revised our approach as described in ``Estimated Take.''
This revised approach is simplified in its use of the available
information while providing a reasonable assessment of the likely
potential for auditory injury, and has the advantage of not relying on
the BOEM PEIS results. While the PEIS results remain a reasonable
assessment of potential effects from a programmatic perspective, and
were based on the best available cetacean density information at the
time the analyses were conducted, they do not use the best cetacean
density information currently available (Roberts et al., 2016), and
also did not recognize that the potential for Level A harassment
occurrence for mid-frequency cetaceans is discountable (described in
detail in ``Estimated Take''). However, the second portion of NRDC's
comment is incorrect: The peak pressure injury zones referred to by
NRDC as extending as far as 1.5 km are not weighted for hearing
sensitivity, as it is inappropriate to do so for exposure to peak
pressure received levels (NMFS, 2018). Applicant-specific zones are
shown in Table 5; all zones based on accumulation of energy are very
small for high-frequency cetaceans. It is unclear what NRDC's
recommendation to ``calculate auditory injury by applying both the
peak-pressure threshold and a metric that accounts for exposure to
multiple shots'' means, as the former is predominant for high-frequency
cetaceans, while zones based on the latter are essentially non-
existent. As recommended by the MMC, we have provided company-specific
Level A harassment zones for each functional hearing group (see Table
5).
Comment: One individual asserted that NMFS fails to account for
variability in group size and distribution of various species, stating
that while the best estimate of take may be a fraction of an individual
in practice either no individuals will be taken, or one or more groups
will be taken. The individual suggested that NMFS should decide whether
it may authorize one or more large groups, rather than estimates of a
fraction of an individual.
Response: We agree with this comment. Accordingly, and as described
in our Notice of Proposed IHAs, we did not propose to authorize take
less than the average group size for any species. In fact, our take
authorization for a group of species deemed ``rare'' was based entirely
on an assumption of one encounter with a group, i.e., we authorize take
equating to one average group size.
Comment: NRDC asserts that NMFS fails to account for forms of
injury that are reasonably anticipated, stating that permanent hearing
loss (i.e., Level A harassment) may occur through mechanisms other than
PTS, and that behaviorally-mediated injury may occur as a result of
exposure to airgun noise. NRDC states that NMFS must account for these
mechanisms in its assessment of potential injury.
Response: NMFS is aware of the work by Kujawa and Liberman (2009),
which is cited by NRDC. The authors report that in mice, despite
completely reversible threshold shifts that leave cochlear sensory
cells intact, there were synaptic level changes and delayed cochlear
nerve degeneration. However, the large threshold shifts measured (i.e.,
maximum 40 dB) that led to the synaptic changes shown in this study are
within the range of the large shifts used by Southall et al. (2007) and
in NMFS's technical guidance to define PTS onset (i.e., 40 dB). It is
unknown whether smaller levels of temporary threshold shift (TTS) would
lead to similar changes or what may be the long-term implications of
irreversible neural degeneration. The effects of sound exposure on the
nervous system are complex, and this will be re-examined as more data
become available. It is important to note that NMFS's technical
guidance incorporated various conservative factors, such as a 6-dB
threshold shift to represent TTS onset (i.e., minimum amount of
threshold shift that can be differentiated in most experimental
conditions); the incorporation of exposures only with measured levels
of TTS (i.e., did not incorporate exposures where TTS did not occur);
and assumed no potential of recovery between intermittent exposures.
NMFS disagrees that consideration of likely PTS is not sufficient to
account for reasonably expected incidents of auditory injury.
There is no conclusive evidence that exposure to airgun noise
results in behaviorally-mediated forms of injury. Behaviorally-mediated
injury (i.e., mass stranding events) has been primarily
[[Page 63294]]
associated with beaked whales exposed to mid-frequency naval sonar.
Tactical sonar and the alerting stimulus used in Nowacek et al. (2004)
are very different from the noise produced by airguns. One should
therefore not expect the same reaction to airgun noise as to these
other sources.
Comment: TGS recommends that NMFS (1) recalculate take estimates to
account for mitigation; (2) remove take estimates associated with the
disallowed use of a mitigation gun; and (3) ensure that we do not
double-count takes when considering takes by both Level A and Level B
harassment.
Response: We agree with these recommendations and have done as
requested; please see ``Estimated Take'' for further detail. We do note
that, with regard to accounting for mitigation in calculating take
estimates, our analysis involved only an accounting of take avoided for
certain species as a result of the implementation of time-area
restrictions. We did not attempt to account for the potential efficacy
of other mitigation requirements in avoiding take.
Comment: The Florida Department of Environmental Protection (FLDEP)
wrote that NMFS needs to be cautious in relying on the efficacy of
mitigation measures to estimate take by Level A harassment,
particularly with regard to North Atlantic right whales. They noted
additional information on the effectiveness of proposed mitigation is
necessary.
Response: While we agree with the commenters that caution is
warranted in assuming that standard mitigation measures, such as
shutdowns, will be effective in avoiding Level A harassment, we note
that our estimation of likely take by Level A harassment does not
substantively rely on such assumptions. As described in ``Estimated
Take,'' auditory injury of mid-frequency cetaceans is highly unlikely,
for reasons unrelated to mitigation. In estimating likely Level A
harassment of high-frequency cetaceans, we did not consider mitigation
at all, as the instantaneous exposures expected to result in auditory
injury are amenable to a straightforward quantitative estimate.
However, our Level A harassment take estimates for low-frequency
cetaceans are based on a more qualitative analysis that does consider
the implementation of mitigation, as is appropriate. We do not assume
in any case that real-time mitigation would be totally effective in
avoiding such instances, but for the theoretical injury zone sizes
considered here for low-frequency cetaceans, which are based on the
accumulation of energy, it is reasonable to assume that large whales
may be observed when close to the vessel. Therefore, shutdown may be
implemented and accumulation of energy halted such that actual
instances of injury should not be considered likely. Our estimated
instances of Level A harassment for low-frequency cetaceans consider
the expected frequency of encounter for different species and the
expectation that mitigation will be effective in avoiding some
instances of Level A harassment, but also the likelihood that for some
species that would be encountered most frequently, some instances of
Level A harassment are likely unavoidable. Specifically for the right
whale, we primarily consider that our required time-area restriction
will avoid most acute exposures of the species (or that comparable
protection will be achieved through implementation of a NMFS-approved
mitigation and monitoring plan at distances between 47-80 km offshore)
(as shown in the very low numbers of estimated take by Level B
harassment, which account for the time-area restriction). Given such a
low assumed encounter rate, the likelihood of Level A harassment for
the species is correctly considered discountable. Please see our
discussion in ``Estimated Take'' for further detail.
Comment: NRDC asserts that NMFS has failed to account for the
effects of stress on marine mammals.
Response: As NRDC acknowledges, we addressed the available
literature regarding potential impacts of stress resulting from noise
exposure in marine mammals. As described in that discussion, stress
responses are complicated and may or may not have meaningful impacts on
marine mammals. NRDC implies that NMFS must (1) enumerate takes
resulting from stress alone and (2) specifically address stress in its
negligible impact analyses. The effects of stress are not
straightforward, and there is no information available to inform an
understanding of whether it is reasonably likely that an animal may
experience a stress response upon noise exposure that would not be
accounted for in NMFS's enumeration of takes via exposure to noise
exceeding 160 dB. NRDC provides no useful information as to how such an
analysis might be carried out. With regard to NMFS's negligible impact
analyses, we believe that the potential effects of stress are addressed
and subsumed within NMFS's considerations of magnitude of effect and
likely consequences. Similarly, NRDC provides no justification as to
why stress would appropriately be considered separately in these
analyses, and no useful recommendation as to how to do so, if
appropriate. We believe we have appropriately acknowledged the
potential effects of stress, and that these potential effects are
accounted for within our overall assessment of potential effects on
marine mammals.
Comment: The MMC recommends that NMFS (1) determine whether the
specific animat density used by Spectrum is appropriate and (2)
depending on the outcome of that assessment, either authorize
uncorrected take numbers from Spectrum's application, or re-estimate
the numbers of Level B harassment takes using a higher animat density.
Response: We appreciate the MMC's consideration of this issue.
Following evaluation of the comment, we confirm that the animat density
used by Spectrum is appropriate. As stated by Marine Acoustics, Inc.
(MAI)--which has years of experience in the field of acoustic modeling
and performed the modeling for Spectrum (as well as ION) according to
state-of-the science best practices--the modeled animat density value
was determined through a sensitivity analysis that examined the
stability of the predicted estimate of exposure levels as a function of
animat density. The modeled density was determined to accurately
capture the full distributional range of probabilities of exposure for
the proposed survey, and is therefore appropriate. In describing the
original modeling, MAI stated that in most cases the animat density
represented a higher density of animats in the simulation than occurs
in the real world. This ``over-population'' allowed the calculation of
smoother distribution tails, and in the final analysis all results were
normalized back to the actual estimated density for the species or
group in question. This remains the case when using the revised density
estimates from Roberts et al. (2016). We disagree with MMC's contention
that the mitigation assumptions used by Spectrum in modeling Level B
harassment takes were inappropriate; therefore, we retain the estimates
proposed for authorization (as modified using the newer Roberts et al.
(2016) density values).
Comment: The FLDEP stated that NMFS should account for uncertainty
in take estimates, including uncertainty about marine mammal density,
sound propagation models, and auditory thresholds, and that these
factors should ``all manifest as uncertainty around take estimates and
be reported in and considered for IHAs.''
Response: We agree with the commenter that it would be useful to
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understand the degree of confidence in take estimates through some
measure of uncertainty around the estimate, and that uncertainty can
accrue through all of the mentioned aspects of the take estimation
process. However, we believe that the take estimates are reasonable
best estimates. Measuring uncertainty around a take estimate is not
something that has been accomplished in the past, and the commenter
provides no recommendation as to how they believe this should be done.
Comment: The NAMA stated that an IHA should be revoked if it is
found that a take by Level A harassment has occurred.
Response: Level A harassment, which is defined as an act with the
potential to injure a marine mammal, may be authorized through an IHA,
as we have done here.
Comment: The New York State Department of Environmental
Conservation stated that the amount of takes by Level A harassment
proposed for humpback whales is considerable when considered in context
of the ongoing UME, and that NMFS should give more consideration to
this concern.
Response: We have considered the ongoing effects of the humpback
whale UME in our evaluation. We also reiterate that Level A harassment
refers to injury, and therefore cannot be directly equated to serious
injury or mortality, and further that the estimated takes by Level A
harassment likely represent only onset of mild PTS. However,
separately, we have revised our estimates of Level A harassment for all
species (see ``Estimated Take''), resulting in much lower estimates for
humpback whales. The revised results of this analysis should obviate
the concern expressed here.
Comment: OCR stated that NMFS should consider the potential use of
ancillary noise sources (e.g., side-scan or multibeam bottom profiling
sonars) in estimating take, and notes that these sources have been
associated with marine mammal strandings.
Response: We did consider this potential avenue of acoustic
exposure. We understand that, generally, vessel operators plan to use
standard navigational echosounders (single beam) operated at relatively
high frequencies (>18 kHz). In addition, it is possible that some
applicants may use a low-level acoustic pinger to help position their
towed gear. It is possible that some marine mammals could detect and
react to signals from these sources (although this is less likely for
low-frequency cetaceans, and these species would not likely detect
signals from these systems if they are operated above 35 kHz). However,
the vast majority of the time echosounders would be in use, so would
airguns which have much higher source levels and are expected to result
in more severe reactions than any associated with echosounders
specifically. We would expect that in most cases, any response would be
to airguns rather than the echosounder itself. We recognize that there
would be limited use of echosounders or pingers while airguns are not
active, for example, when vessels are in transit from port to areas
where surveys will occur. However, we do not believe this results in
meaningful exposure to marine mammals since, given the lower source
levels and higher frequencies of echosounders and pingers, animals
would need to be very close to the transducer to receive source levels
that would produce a behavioral response (Lurton, 2016), much less one
that would result in a response of a degree considered to be take.
In extreme circumstances, some echosounders and pingers may also
have the potential to cause injury, and in one case evidence indicates
such a system likely played a contributing role in a cetacean stranding
event. However, injury (or any threshold shift) is even less likely
than behavioral responses since animals would need to be even closer to
the transducer for these to occur. It is also important to note that
the system implicated in the stranding event was a lower-frequency (12-
kHz), higher-power deepwater mapping system; typical navigational
systems, including those that the applicants here would use, would have
lower potential to cause similar responses. Kremser et al. (2005)
concluded the probability of a cetacean swimming through the area of
exposure when such sources emit a pulse is small, as the animal would
have to pass at close range and be swimming at speeds similar to the
vessel in order to receive multiple pulses that might result in
sufficient exposure to cause TTS. This finding is further supported by
Boebel et al. (2005), who found that even for echosounders with source
levels substantially higher than those proposed here, TTS is only
possible if animals pass immediately under the transducer. Burkhardt et
al. (2013) estimated that the risk of injury from echosounders was less
than three percent that of vessel strike, which is considered extremely
unlikely to occur such that it is discountable. In addition, modeling
by Lurton (2016) of multibeam echosounders indicates that the risk of
injury from exposure to such sources is negligible.
Navigational echosounders are operated routinely by thousands of
vessels around the world, and to our knowledge, strandings have not
been correlated with their use. The echosounders and pinger proposed
for use differ from sonars used during naval operations, which
generally have higher source levels, lower frequencies, a longer pulse
duration, and more horizontal orientation than the more downward-
directed echosounders. The sound energy received by any individuals
exposed to an echosounder during the proposed seismic survey activities
would be much lower relative to naval sonars, as would be the duration
of exposure. The area of possible influence for the echosounders is
also much smaller, consisting of a narrow zone close to and below the
source vessels as described previously for TTS and PTS. Because of
these differences, we do not expect the proposed echosounders and
pinger to contribute to a marine mammal stranding event. In summary,
any effects that would be considered as take are so unlikely to occur
as a result of exposure from ancillary acoustic sources as to be
considered discountable.
Marine Mammal Protection Act--General
Comment: Several groups indicated a belief that NMFS's proposal to
issue the five IHAs contradicts Congressional intent behind the MMPA.
For example, Clean Ocean Action (COA) stated that issuance of the IHAs
would be incompatible with the original intent of the MMPA. Sea
Shepherd Legal stated that the legislative history of the MMPA makes
clear that the precautionary principle must be applied and bias must
favor marine mammals, and opines that NMFS's proposed issuance of the
IHAs ``undermines the MMPA's prioritization of conservation.''
Response: NMFS disagrees that these actions contradict any
requirement of the MMPA or are contrary to Congressional intent as
expressed in relevant provisions of the statute. Neither the MMPA nor
NMFS's implementing regulations include references to, or requirements
for, the precautionary approach, nor is there a clear, agreed-upon
description of what the precautionary approach is or would entail in
the context of the MMPA or any specific activity. Nevertheless, the
MMPA by nature is inherently protective, including the requirement to
mitigate to the lowest level practicable (``least'' practicable adverse
impacts, or ``LPAI,'' on species or stocks and their habitat). This
requires that NMFS assess measures in light of the LPAI standard. To
ensure that we fulfill that requirement, NMFS considers all
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potential measures (e.g., from recommendations or review of available
data) that have the potential to reduce impacts on marine mammal
species or stocks, their habitat, or subsistence uses of those stocks,
regardless of whether those measures are characterized as
``precautionary.''
Comment: Several groups stated that the duration of the public
comment period was inadequate. A group of fourteen U.S. Senators urged
NMFS to extend the comment period to at least 150 days (30 for each
applicant). They wrote that publishing the notice of proposed IHAs had
little notice, a short comment period, and no public hearings, adding
that the notice of proposed IHAs addresses two applications that NMFS
had not previously made available for public review. Some commenters
decried what they perceived as a lack of stakeholder outreach. Multiple
groups requested that NMFS hold public hearings in the affected regions
about the proposed IHAs and their potential impacts.
Response: NMFS has satisfied the requirements of the MMPA, which
requires only that NMFS publish notice of a proposed authorization and
request public comment for a period of 30 days. In fact, NMFS exceeded
this requirement by extending the public comment period by 15 days, for
a total period of 45 days. By publishing a joint notice of the five
proposed IHAs rather than five separate concurrent notices, NMFS
provided for more efficient public review and comment on these
substantially similar actions. Although NMFS acknowledges that these
are five separate actions, there is no requirement to provide for
consecutive review periods (i.e., five 30-day periods totaling 150
days). Although not required, NMFS in 2015 published a notice of
receipt of applications received to afford opportunity for public
review and comment. Therefore, NMFS provided an opportunity for review
of the applications for 30 days followed by a 45-day review of the
proposed IHAs, for a total of 75 days of review--far above what is
required by the MMPA. As stated earlier in this document, the
additional two applications received following the 2015 review were
substantially similar to those offered for review, and we determined
that publishing a notice of their receipt would not provide any
additional useful information.
Overall, we believe that there has been sufficient opportunity for
public engagement with regard to the proposed surveys, through
opportunities associated with NMFS's consideration of the requested
IHAs under the MMPA and those associated with BOEM's consideration of
requested permits under OCSLA (or through other associated statutory
requirements). The public, coastal states, and other stakeholders have
had substantial opportunity for involvement via processes related to
the Coastal Zone Management Act (CZMA), NEPA, OCSLA, and the MMPA. In
2014, BOEM completed their PEIS, with NOAA acting as a cooperating
agency in development of the PEIS. During EIS scoping, BOEM offered two
separate comment periods and held seven public meetings in coastal
states. The draft PEIS was made available for public review and comment
for 94 days. Public hearings were held in eight coastal states.
Subsequently, the final PEIS was made available for public comment for
90 days prior to BOEM's issuance of a Record of Decision. After
completion of the 2014 PEIS, BOEM made all geophysical survey permit
requests available for public review and comment for 30 days. With
NMFS's participation, BOEM subsequently held eight open house meetings
in coastal states for the public to learn more about the proposed
surveys and to provide input to the permitting process. In addition,
NOAA and BOEM engaged with coastal states as required by the CZMA
federal consistency provision.
Comment: NRDC states that the specified activities have the
potential to kill and seriously injure marine mammals, and that NMFS
cannot therefore authorize the requested incidental take via an IHA.
NRDC specifically contends that behavioral disturbance (i.e., Level B
harassment) can result in more severe outcomes (i.e., Level A
harassment or serious injury or mortality) through secondary effects,
and that NMFS must consider this. Similarly, Oceana and other
commenters suggest that Level A harassment (i.e., auditory injury)
cannot be authorized via an IHA, as it is equivalent to serious injury
or mortality. In this same vein, commenters relate Level A harassment
to potential biological removal (PBR) levels, a metric used to evaluate
the significance of removals from a population (i.e., serious injury or
mortality).
Response: We strongly disagree that mortality or serious injury are
reasonably anticipated outcomes of these specified activities, and the
commenters do not provide compelling evidence to the contrary. Instead,
commenters present speculative potentialities, including the contention
that behavioral disturbance will lead to heightened risk of strike or
predation. Moreover, the specific example given by NRDC--that the
migratory path for right whales lies ``in the middle of the'' survey
area--is plainly incorrect. The migratory path for right whales lies
along the continental shelf (Schick et al., 2009; Whitt et al., 2013;
LaBrecque et al., 2015), whereas the survey area extends out to 350 nmi
from shore, with most survey effort planned for waters where right
whales do not occur (i.e., waters greater than 1,500 m deep; Roberts et
al., 2017). More importantly, we require that applicants maintain a
minimum standoff distance of 90 km from shore from November through
April (or that comparable protection be achieved through implementation
of a NMFS-approved mitigation and monitoring plan at distances between
47-80 km offshore), encompassing the expected migratory path and season
and obviating any concern regarding potential secondary effects on
migrating right whales.
Separately, section 101(a)(5)(D) of the MMPA, which governs the
issuance of IHAs, indicates that the ``the Secretary shall authorize .
. . . taking by harassment [ . . . . ]'' The definition of
``harassment'' in the MMPA clearly includes both Level A and Level B
harassment.
Last, PBR is defined in the MMPA (16 U.S.C. 1362(20)) as ``the
maximum number of animals, not including natural mortalities, that may
be removed from a marine mammal stock while allowing that stock to
reach or maintain its optimum sustainable population'' and is a measure
to be considered when evaluating the effects of mortality or serious
injury on a marine mammal species or stock. Level A harassment is not
equivalent to serious injury and does not ``remove'' an individual from
a stock. Therefore, it is not appropriate to use the PBR metric to
directly evaluate the effects of Level A harassment on a stock in the
manner suggested by commenters.
Comment: ION expressed concern regarding proposed IHA language
indicating that ``taking of any other species of marine mammal is
prohibited and may result in the modification, suspension, or
revocation'' of an IHA, requesting that NMFS remove this language.
Applicants also expressed concern about not being able to avail
themselves of the IHAs while they are effective.
Response: The referenced language is standard text in issued IHAs,
which acknowledges that, while unlikely and unexpected, species for
which take is not authorized may be observed and unintentionally taken.
Absent extenuating circumstances, it is unlikely that such an
occurrence would result in
[[Page 63297]]
the suspension or revocation of an IHA. Rather, in the event that an
observation is made of an unusual species for which take is not
authorized, we would consider whether it is likely that the take
warrants a modification of the IHA in order to include future take
authorization for that species, or whether it is more likely that the
observation would not occur again. NMFS has also included a provision
for an IHA holder to request suspension of the IHA when operations must
cease for reasons outside the holder's control, excluding certain
circumstances, for a limited period.
Least Practicable Adverse Impact
Comment: NRDC believes NMFS relies on a ``flawed interpretation''
of the least practicable adverse impact standard. They state that NMFS
(1) wrongly imports a population-level focus into the standard,
contrary to the ``clear'' holding of the Ninth Circuit in NRDC v.
Pritzker; (2) inappropriately ``balances'' or weighs effectiveness
against practicability without sufficient analysis, counter to
Pritzker, using the seasonality of Area #5 and NMFS's core abundance
approaches as examples; and (3) must evaluate measures on the basis of
practicability (which connotes feasibility), not practicality (which
connotes usefulness)--and evaluating on the basis of practicality would
be arbitrary and capricious.
Response: We carefully evaluated the Ninth Circuit's opinion in
Pritzker and believe we have fully addressed the Court's concerns. Our
discussion of the least practicable adverse impact standard in the
section entitled ``Mitigation'' explains why we believe a population
focus is a reasonable interpretation of the standard. With regard to
the second point, we disagree that the Ninth Circuit's opinion requires
such a mechanical application of the factors that must be considered in
assessing mitigation options. Finally, we agree with the commenter that
we must evaluate measures on the basis of practicability, and for these
IHAS we have done so. Our assessment of measures for practicability
looked at appropriate considerations, as demonstrated by our discussion
in this Notice. This included cost and impact on operations. We note
that although not directly relevant for these IHAs, in the case of a
military readiness activity, practicality of implementation is
explicitly part of the practicability assessment. Thus, the two
concepts are not entirely distinct.
Comment: In determining whether proposed IHAs meet the least
practicable adverse impact (LPAI) standard, the MMC recommends that
NMFS (1) identify the potential adverse impacts that it has identified
and is evaluating; (2) specify what measures might be available to
reduce those impacts; and (3) evaluate whether such measures are
practicable to implement. The MMC further suggests that NMFS provided
``virtually no analysis to support'' our conclusions.
Response: The MMC identifies a specific manner in which it
recommends NMFS consider applicable factors in its least practicable
adverse impact analysis, however, NMFS has clearly articulated the
agency's interpretation of the LPAI standard and our evaluation
framework in the ``Mitigation'' section of this notice. NMFS disagrees
that analysis was not provided to support our least practicable adverse
impact findings. Specifically, NMFS identifies the adverse impacts that
it is considering in the LPAI analysis, and comprehensively evaluates
an extensive suite of measures that might be available to reduce those
impacts (some of which are adopted and some that are not) both in the
context of their expected ability to reduce impacts to marine mammal
species or stocks and their habitat, as well as their practicability
(see ``Mitigation'' and ``Negligible Impact Analyses and
Determinations'' sections).
Comment: TGS recommended that NMFS ``model how many shut-down and
delay actions would be expected for a survey'' in evaluating
practicability, suggesting that ``animat modeling could be used to
accomplish this estimate.''
Response: NMFS is not aware of data sources that would
appropriately inform such an analysis, and does not agree that such an
analysis is either practical or necessary. Moreover, we believe we have
addressed the commenter's concern by removing a number of shutdown
measures (in response to other public comments) that we determined were
likely ineffective and/or impracticable or otherwise unwarranted, thus
minimizing the accumulation of potential for shutdown and delay
actions. We also note that seismic operators have successfully and
practicably implemented shutdowns in multiple regions, both in the
United States and in other countries where seismic mitigation protocols
have been prescribed, and that larger shutdown zones have previously
been required of operators in the U.S. Arctic as well as for research
seismic cruises, without any known practicability issues. We have
appropriately accounted for issues related to practicability in our
analysis of the appropriate suite of required mitigation measures.
Negligible Impact
Comment: As described briefly in a previous comment and response,
NRDC asserts that NMFS should conduct a combined negligible impact
analysis for all five specified activities, in consideration of the
aggregate take across all five surveys in the same geographical region,
over the same period of time, and with ``substantially similar impacts
on marine mammals.'' NRDC states that NMFS's failure to do so does not
meet our legal obligations under the MMPA and is ``contrary to common
sense and principles of sound science.'' Other commenters offer similar
comments. NRDC cites to legislative history that indicates ``specified
activity'' includes all actions for which ``the anticipated effects
will be substantially similar.'' H.R. Rep. No. 97-228 (Sept. 16, 1981),
as reprinted in 1981 U.S.C.C.A.N. 1458, 1469. Further, NRDC cites to
NMFS's 1989 implementing regulations as further evidence that NMFS must
``evaluate the impacts resulting from all persons conducting the
specified activity, not just the impacts from one entity's
activities.'' Based on this, NRDC argues that NMFS must make a finding
that the authorized activity--which includes all five IHA
applications--will have a negligible impact on the affected species or
stocks.
Response: We considered five distinct specified activities and,
therefore, performed five distinct negligible impact analyses. As we
said in a previous response to comment, we believe the ``specified
activity'' for which incidental take coverage is being sought under
section 101(a)(5)(D) is appropriately defined and described by the
applicant. Here there are five specified activities, with a separate
applicant for each.
Although NRDC's comment correctly cites the pertinent language from
section 101(a)(5)(D) (which was enacted in 1994), it refers to
legislative history from 1981 in support of its argument. But that
legislative history corresponds to Congress' enactment of the provision
for incidental take regulations. Because the IHA provisions were added
in 1994, citations from the 1981 legislative history cannot accurately
be referenced as statements made ``in enacting this provision.'' More
substantively, the sentence from which NRDC quotes was, in our view,
for the purpose of instructing the agencies to avoid promulgating
incidental take regulations that are overly broad in their scope (``It
is the intention of the Committee that [ . . . ] the specified activity
[ . . . ] be narrowly identified so that
[[Page 63298]]
the anticipated effects will be substantially similar.''). Similarly,
the discussion from NMFS's and the U.S. Fish and Wildlife Service's
1989 implementing regulations (again, before the 1994 enactment of
section 101(a)(5)(D)) was in reference to section 101(a)(5)(A), the
provision for incidental take regulations. There the focus was on
ensuring that the negligible impact evaluation for an incidental take
regulation under section 101(a)(5)(A)--not incidental harassment
authorizations under section 101(a)(5)(D)--included the effects of the
total taking by all the entities anticipated to be conducting the
activity covered by the incidental take regulation.
We do not mean to suggest that the legislative history for section
101(a)(5)(A) and our implementing regulations that preceded enactment
of section 101(a)(5)(D) have no application to that section. We
recognize there is considerable overlap between the two provisions.
However, there are enough differences that the two provisions should
not be casually conflated with one another.
Comment: The Associations state that they concur with NMFS's
preliminary determinations of negligible impact on the affected species
or stocks. However, their comments go on to claim that the
``magnitude'' and ``impact'' ratings that inform our negligible impact
determinations as part of our negligible impact analysis framework are
overly conservative, and that they disagree with these aspects of our
negligible impact analyses.
Response: We appreciate the Associations' concurrence with our
overall determinations. However, we disagree with the statements
regarding aspects of our negligible impact analyses, and feel that
these statements to some degree reflect a misunderstanding of the
framework elements. In support of their assertion, the Associations
claim that ``high'' and ``moderate'' magnitude ratings ``have never
been observed in the multi-decade history of offshore seismic
exploration [ . . . . ]'' Magnitude ratings reflect only the amount of
take that is estimated, as well as the spatial and temporal scale over
which the take is expected to occur in relation to what is known
regarding a stock's range and seasonal movements; therefore, it is
incorrect to reference what has or has not ``been observed'' in
disputing the validity of the given magnitude ratings. The Associations
also claim that no survey has had more than an ``insignificant'' impact
on a marine mammal species or stock, without explaining the meaning
that they assign to this term in context of their comments or providing
any evidence (as we have stated, lack of evidence of ``significance''
does not constitute evidence of ``insignificance''). As this term bears
no relevance to the MMPA's ``negligible impact,'' we cannot comment on
the claim. With regard to the Associations' comment that our assigned
impact ratings are too high, we again disagree (noting that these
ratings are developed using the formula described for our negligible
impact framework); however, absent any constructive recommendations
relating to the development of the impact ratings or our framework
overall, we cannot respond further.
Comment: The MMC recommends that NMFS evaluate the numbers of Level
A harassment takes, in concert with the Level B harassment takes, using
the negligible impact analysis framework.
Response: This comment appears based on a mistaken assumption that
we ``assessed only the proposed Level B harassment takes'' in our
negligible impact analyses. It is correct that we did not define
quantitative metrics relating to amount of potential take by Level A
harassment. However, as we state in the section entitled ``Negligible
Impact Analyses and Determinations,'' the authorized taking by Level A
harassment is so low as to not warrant such detailed analysis. We
addressed the likely impacts of the minimal amount of takes expected by
Level A harassment, stating that the expected mild PTS would not likely
meaningfully impact the affected high-frequency cetaceans, and may have
minor effects on the ability of affected low-frequency cetaceans to
hear conspecific calls and/or other environmental cues. For all
applicants, the expected effects of Level A harassment on all stocks to
which such take may occur is appropriately considered de minimis.
Comment: NRDC claims that NMFS underestimates the ``magnitude''
component of the negligible impact analyses.
Response: NRDC suggests that the negligible impact framework used
in our Notice of Proposed IHAs positions a ``de minimis'' amount of
take as determinative of an ultimate ``de minimis'' impact rating.
Although not stated explicitly by NRDC, we agree that this was
inappropriate and have revised this aspect of our negligible impact
framework. In effect, the proposed approach meant that a de minimis
amount of take, which would necessarily lead to a de minimis magnitude
rating, rendered considerations of likely consequences for affected
individuals irrelevant. For example, mysticete whales with a de minimis
amount of take were automatically assigned an overall de minimis impact
rating, as consequences were considered not applicable in cases where a
de minimis magnitude rating was assigned. However, the assessed level
of potential consequences for individual baleen whales of ``medium''--
which is related to inherent vulnerabilities of the taxon and other
existing population stressors, and is therefore not dependent on the
specific magnitude rating--would still exist, regardless of the amount
of take. Under our revised approach, a mysticete whale with a de
minimis amount of take is assigned a low impact rating, in light of the
medium consequences rating. These changes are described further in the
section entitled ``Negligible Impact Analyses and Determinations.''
NRDC asserts that impacts resulting from each of the five separate
specified activities on the endangered North Atlantic right whale would
be greater than negligible, stating that it is ``inconceivable'' that
impacts should be considered anything less than ``high,'' regardless of
the expected avoidance of right whales in time and space. We have
addressed concerns regarding North Atlantic right whales in greater
detail elsewhere in these comment responses. While we acknowledge that
there will be some effects to individual right whales, as it is not
possible to conduct these activities without the potential for impacts
to whales that venture outside of areas where they are expected to
occur or that undertake migration at atypical times, impacts to the
population are in fact effectively minimized for each of these
specified activities. As described later in this document, we have
revised our exposure analysis for right whales using the latest and
best available scientific information, and have appropriately revised
our prescribed mitigation on the basis of that information, as well as
public comment, in such a way as to reasonably avoid almost all
potential right whale occurrence. We also include real-time mitigation
that would minimize the effect of any disturbance on a right whale, in
the unexpected event that an individual was encountered in the vicinity
of a survey. Accordingly, the impact ratings for mysticetes are at
least ``low'' versus ``de minimis'' (as stated above, we agree that the
impact rating should likely be greater than de minimis given the
inherent vulnerabilities of the species).
NRDC goes on to state that NMFS uses a ``non-conservative'' metric
in characterizing the amount of take, and
[[Page 63299]]
suggests that we should adopt Wood et al. (2012)'s more conservative
approach for ESA-listed species. NRDC does not explain how this
recommendation will better satisfy the statutory requirements of the
MMPA. As stated by Wood et al. (2012), development of metrics for
assessment of the magnitude of effect is considered particularly
subjective. Rather than invent new metrics in the absence of any
specific rationale or guidance, we retain use of those given by Wood et
al., which are produced through expert judgment. We disagree that the
more conservative approach applied by Wood et al. (2012) for ESA-listed
species is appropriate. We believe that the assessment of amount of
take is a generic consideration, i.e., that the metrics used to assess
this factor are appropriately applied similarly to all species.
Contextual factors, such as the status of the species, are applied
elsewhere in the analysis, e.g., through consideration of likely
consequences to individuals or as a second-order function of the
mitigation that is developed in reflection of specific concerns about a
given species. NRDC's implication that we did not take account of
vulnerable populations in our negligible impact framework is incorrect.
Comment: NRDC asserts that the evaluation of likely consequences to
individuals from species other than mysticete whales in our negligible
impact analyses is ``problematic.''
Response: Overall, NRDC basically provides a blanket suggestion
that for all species impacts should be considered to be higher than we
have determined after careful consideration of the available science.
NRDC also repeatedly claims that we have provided no rational basis for
our findings. While we acknowledge that we bear the responsibility to
support our statutory findings, we believe we have satisfied that
requirement and, further, NRDC does not provide adequate justification
or evidence to support their claims.
For sperm whales, NRDC demands that the likely consequences to
individuals be considered ``high'' rather than ``medium,'' as we have
done (on the basis of presumed heightened potential for disruption of
foraging activity). In so doing, NRDC primarily relies upon Miller et
al. (2009), as has NMFS in assuming some heightened potential for
foraging disruption. However, the evidence provided by the available
literature is not nearly as clear as NRDC's comment implies. We agree
that the work of Miller et al. (2009) indicates that sperm whales in
the Gulf of Mexico are susceptible to disruption of foraging behavior
upon exposure to relatively moderate sound levels at distances greater
than the required general exclusion zone. However, NRDC misstates the
results of the study in claiming that a nearly 20 percent loss in
foraging success was documented. Rather, the authors report that buzz
rates (a proxy for attempts to capture prey) were approximately 20
percent lower, meaning that the appropriate interpretation would be
that foraging activity (versus foraging success) was reduced by 20
percent (Jochens et al., 2008). This is an important distinction, as
the former implies a cessation of activity--which may include increased
resting bouts at the surface--during the relatively brief period that
the surveys transit through the whale's foraging area, whereas the
latter implies that the whale is continuing to expend energy in the
hunt for food, without reward. Moreover, while we do believe that these
results support our contention that exposure to survey noise can impact
foraging activity, other commenters have interpreted them differently,
e.g., by focusing on the finding that exposed whales did not change
behavioral state during exposure or show horizontal avoidance (a
finding replicated in other studies, e.g., Madsen et al., 2002; Winsor
et al., 2017), or that the finding of reduced buzz rates was not a
statistically significant result. In referencing Bowles et al. (1994),
NRDC fails to state that the observed cessation of vocalization was
likely in response to a low-frequency tone (dissimilar to airgun
signals), though a distant airgun survey was noted as producing signals
that were detectable above existing background noise. However, most
importantly, we expect that the context of these transitory 2D
surveys--as compared with 3D surveys that may occur for a longer
duration in a given location, or with repeated survey activity as may
occur in an area such as the Gulf of Mexico--means that the potential
impacts of the possible reduction in foraging activity (i.e., likely
consequences on individuals) is limited. More recently, Farmer et al.
(2018) developed a stochastic life-stage structured bioenergetic model
to evaluate the consequences of reduced foraging efficiency in sperm
whales, finding that the ultimate effects on reproductive success and
individual fitness are largely dependent on the duration and frequency
of disturbance--which are expected to be limited in relation to these
specified activities. Thus, we believe our conclusion of ``medium''
likely consequences is appropriate.
With regard to Kogia spp., NRDC again suggests that NMFS must
increase the level of assumed severity for likely consequences to
individuals. While we agree that the literature with regard to kogiid
life history is sparse, what literature is available (as cited in our
Notice of Proposed IHAs) indicates that these species should be
considered as having a reasonable compensatory ability when provoked to
temporary avoidance of areas in the vicinity of active surveys. None of
NRDC's statements on this topic support their contention that these
consequences should be considered as more severe, i.e., the notion that
there is little information available regarding stock structure is not
related to the likely consequences to individuals of disturbance. NRDC
assumes that such temporary avoidance necessarily results in
``displacement from optimal to suboptimal habitat'' without any
support. Moreover, it appears that NRDC misapprehends the conceptual
underpinnings of our negligible impact analytical framework. The
expected degree of disturbance (``take'') is determined in the
``Estimated Take'' section, and then is coupled with an understanding
of the spatial and temporal scale of such disturbance relative to the
stock range. Only then is this comprehensive magnitude rating combined
with the expectation of the likely consequences of the given magnitude
of effect to yield an overall impact rating that is then considered
with other relevant contextual factors, such as mitigation and stock
status, in informing the negligible impact determination (Figure 5). By
seemingly conditioning its premise on the acoustically sensitive nature
of kogiids, which is incorporated into the take estimates and accounted
for in the mitigation requirements, NRDC would have us overly weight
this aspect of their life history. Our assigned consequences for Kogia
spp. is appropriate and based on the limited available literature.
Similarly, for delphinids (for which NRDC also urges a more severe
assumption of likely consequence to individuals of the given
disturbance), NRDC states that the consequences must be considered
higher when the magnitude is high. Again, this is a misapprehension of
the framework: The assigned ``consequences'' factor is independent of
the magnitude rating, and is designed to account for aspects of a
species life history that may make individuals from that species more
or less susceptible to a biologically significant degree of impact from
a
[[Page 63300]]
given level of disturbance. NRDC's additional statements regarding
delphinids appear to again cherry-pick available literature in support
of its preferred position, e.g., NRDC cites reactions of dolphins to
Navy training involving explosive detonations (a dissimilar activity)
and suggests that spotted dolphins are susceptible to greater
disturbance on the basis of Weir (2008), claiming that this paper
indicates ``pronounced response of spotted dolphins to operating
airguns'' and supposedly heightened sensitivity. We do agree that the
available observational data (e.g., Barkaszi et al., 2012; Stone,
2015a) show that, in contrast to common anecdotal statements suggesting
that dolphins do not react at all to airgun noise, dolphins overall
show increased distances to the noise source or even avoidance when
airguns are operating. However, as stated elsewhere, these reactions
may not even be appropriately considered as take (e.g., Ellison et al.,
2012), much less take to which some meaningful biological significance
should be assigned. In fact, Weir (2008) concludes that, while spotted
dolphin encounters occurred at a significantly greater distance from
the airgun array when the guns were firing, there was no evidence of
displacement from the study area, indicating that even for this
supposedly more sensitive species, greater likely consequences would
not be expected. As indicated by Weir (2008), these responses may be
short-term and also occur over relatively short ranges from the source.
NRDC concludes its criticism of this aspect of our negligible
impact analyses by demanding that we weight this assessment of likely
consequences to individuals more highly in the determination of the
overall impact rating. However, this appears to again evidence a
misapprehension of our framework and its function. We certainly agree
that an activity that is found to take small numbers of marine mammals
may not be found to satisfy the negligible impact standard. However,
here, as in their criticism of NMFS's approach to the small numbers
analysis, NRDC inappropriately conflates the two findings. Here, NRDC
seems to confuse a low magnitude of effect with the independent small
numbers finding, rather than understand this magnitude factor as an
important input to the development of the impact rating. As described
in greater detail in our section entitled ``Negligible Impact Analyses
and Determinations,'' the impact rating represents the coupling of the
magnitude rating and the likely consequences to individuals in order to
represent the potential impact to the stock (before considering other
contextual factors). Therefore, although the likely consequences to
individuals of incidental take may be high, if the magnitude of effect
is low, then the impact to the stock will not likely be high. NRDC's
example indicates that it prefers that the likely consequences to
individuals be determinative of the impact rating, i.e., they state
that it is inappropriate for a low magnitude rating and high
consequences rating to couple to produce a moderate impact rating. Our
development of these rating matrices (Tables 8 and 9) are based on
expert review (Wood et al., 2012) and appropriately account for the
factors illustrated in Figure 5.
Comment: NRDC claims that the negligible impact analyses are
inappropriately reliant upon the prescribed mitigation and, further,
that the mitigation will be ineffective.
Response: First, NMFS did not rely solely on the mitigation in
order to reach its findings under the negligible impact standard. As is
stated in our specific analyses, consideration of the implementation of
prescribed mitigation is one factor in the analyses, but is not
determinative in any case. In certain circumstances, mitigation is more
important in reaching the negligible impact determination, e.g., when
mitigation helps to alleviate the likely significance of taking by
avoiding or reducing impacts in important areas. Second, while NRDC
dismisses the importance of our prescribed mitigation by stating that
it is ``unsupported by evidence,'' NRDC offers no support for their
conclusions.
For example, with regard to the North Atlantic right whale,
consideration of the mitigation in our negligible impact analyses was
appropriate. That is, it was appropriate to weigh heavily in our
analyses mitigation that would avoid most exposures of right whales to
noise at levels that would result in take. We acknowledge that our
proposed mitigation for right whales was not sufficient. As described
in greater detail in previous comment responses, as well as in the
section entitled ``Mitigation,'' we re-evaluated our proposed
mitigation in light of the public comments we received and on the basis
of the best available information.
NRDC elsewhere stresses the importance of developing appropriate
habitat-based mitigation--that is, avoiding impacts in areas of
importance for marine mammals--and not relying solely on ``real-time''
mitigation (e.g., shutdowns) that allows impacts in those areas but
minimizes the duration and intensity of those impacts. Yet despite our
development of time-area measures for those species where the available
information supports it, NRDC discounts the benefit of avoiding
disturbance of sensitive and/or deep-diving species in areas where they
are expected to be resident in greatest numbers. Claims that our
prescribed time-area restrictions are ineffective and
``unsubstantiated''--and therefore apparently should not be considered
in our negligible impact analyses--are contradicted by NRDC's
statements that habitat-based mitigation are necessary (``Time and
place restrictions designed to protect important habitat can be one of
the most effective available means to reduce the potential impacts of
noise and disturbance on marine mammals.'' (Citing p. 61 of NRDC's
letter)). However, our revised time-area restriction for right whales
(or requirement that comparable protection is achieved through
implementation of a NMFS-approved mitigation and monitoring plan at
distances between 47-80 km offshore) may have alleviated some of the
concerns expressed in the comment.
NRDC also misunderstands the degree to which we rely on shutdowns
for sensitive or vulnerable species, including right whales and beaked
whales, at extended distances. We agree that these measures in and of
themselves are not likely to carry substantial benefit, especially for
cryptic species such as beaked whales that are unlikely to be observed.
The prescribed habitat-based mitigation, i.e., time-area restrictions,
is obviously more important in minimizing impacts to these species.
However, having determined practicability, we also believe that it
makes sense to minimize the duration and intensity of disturbance for
these species when they are observed, and so include them in the suite
of prescribed measures and discuss them where appropriate. Despite
their dismissal of these requirements, we presume NRDC agrees that the
duration and intensity of disturbance of sensitive species should be
minimized where practicable.
In summary, we have prescribed practicable mitigation that largely
eliminates takes of North Atlantic right whales, as indicated by the
best available science and further minimizes impacts by mitigating for
duration and intensity of exposures. Separately, we have developed
mitigation that protects use of some of the most important habitat in
the region for other sensitive species. We consider these measures
appropriately as mitigating factors in the
[[Page 63301]]
context part of our negligible impact analyses.
Comment: Oceana asserts that our findings of negligible impact are
improper. In so doing, they make points that are substantively
responded to elsewhere in these comment responses. In addition, they
also make repeated reference to the PBR value, claiming that where
harassment takes exceed the PBR value for a stock, NMFS must deny the
IHA request for failure to meet the negligible impact standard.
Response: We reiterate that the PBR metric concerns levels of
allowable removals from a population, and is not directly related to an
assessment of negligible impact for these specified activities, which
do not involve any expected potential for serious injury or mortality.
As noted previously, PBR is not an appropriate metric with which to
evaluate Level B harassment and NMFS has described and used an
analytical framework that is appropriate. We appropriately do consider
levels of ongoing anthropogenic mortality from other sources, such as
commercial fisheries, in relation to calculated PBR values as an
important contextual factor in our negligible impact analysis
framework, but a direct comparison of takes by harassment to the PBR
value is not germane. While it is conceptually possible to link
disturbance to potential fitness impacts to individuals over time
(e.g., population consequences of disturbance), we have no evidence
that is the case here.
Small Numbers
Comment: The MMC and multiple commenters recommend that NMFS
provide additional explanation to support its selection of the 30-
percent limit on marine mammal taking as meeting the small numbers
determination for the proposed authorizations. NRDC states that the
interpretation of ``small numbers'' presented by NMFS in our Notice of
Proposed IHAs is contrary to the plain meaning and purpose of the MMPA,
in part because NMFS did not provide a reasoned basis for the take
limit proposed (i.e., 30 percent) (MMC and others similarly recommended
that NMFS provide additional explanation to support its selection of
the 30-percent limit on marine mammal taking as meeting the small
numbers determination for the proposed authorizations). NRDC makes four
specific claims. First, NRDC states that 30 percent cannot be
considered a ``small number.'' Second, NRDC states that Congress
intended that takes be limited to ``infrequent, unavoidable''
occurrences, and that NMFS has not explained why the taking would
infrequent or unavoidable. Third, NRDC contends that NMFS should define
different small numbers thresholds on the basis of conservation status
of individual species. Finally, NRDC believes that NMFS must account
for ``additive and adverse synergistic effects'' that may occur due to
multiple concurrent surveys in conducting a small numbers analysis.
Response: NMFS agrees that the Notice of Proposed IHAs did not
provide adequate reasoning for the 30 percent limit. Please see the
``Small Numbers Analyses'' section of this Notice. However, we disagree
with NRDC's arguments on this topic. Although NMFS has struggled to
interpret the term ``small numbers'' given the limited legislative
history and the lack of a biological underpinning for the concept, we
have clarified and better described our approach to small numbers. As
discussed in the section entitled ``Small Numbers Analyses,'' we
describe that the concept of ``small numbers'' necessarily implies that
there would also be quantities of individuals taken that would
correspond with ``medium'' and ``large'' numbers. As such, we have
established that one-third of the most appropriate population abundance
number--as compared with the assumed number of individuals taken--is an
appropriate limit with regard to ``small numbers.'' This relative
approach is consistent with Congress's statement that ``[small numbers]
is not capable of being expressed in absolute numerical limits'' (H.R.
Rep. No. 97-228).
NRDC claims that a number may be considered small only if it is
``little or close to zero'' or ``limited in degree.'' While we do not
accept that a dictionary definition of the word ``small'' is an
acceptable guide for establishment of a reasoned small numbers limit,
we also note that NRDC cherry-picks the accepted definitions in support
of its favored position. The word ``small'' is also defined by Merriam-
Webster Dictionary as ``having comparatively little size,'' which
comports with the small numbers interpretation developed by NMFS and
offered here. See www.merriam-webster.com/dictionary/small. NRDC
cherry-picks the relevant language by claiming that Congress intended
that the agency limit takes to those that are ``infrequent,
unavoidable'' occurrences. The actual Congressional statement is that
taking of marine mammals should be ``infrequent, unavoidable, or
accidental.'' This language implies that allowable taking may in fact
be frequent if it is unavoidable or accidental, both of which are the
case, even though, in the case of a large-scale, sound-producing
activity in areas where marine mammals are present, the takes are not
``infrequent.''
The argument to establish a small numbers threshold on the basis of
stock-specific context is unnecessarily duplicative of the required
negligible impact finding, in which relevant biological and contextual
factors are considered in conjunction with the amount of take.
Similarly, NRDC's assertion that take from multiple specified
activities should be considered in additive fashion when making a small
numbers finding is not required by section 101(a)(5)(D) of the MMPA. We
are unclear whether the logic presented in this comment suggests only
that a single small numbers analysis should be undertaken for the five
separate specified activities considered herein, or whether NRDC
believes that all ``taking'' to which a given stock may be subject from
all ongoing anthropogenic activities should be considered in making a
small numbers finding for a given specified activity. Regardless, these
suggestions from NRDC are not founded in any relevant requirement of
statute or regulation, discussed in relevant legislative history, or
supported by relevant case law.
Comment: The MMC recommends that, in developing generally
applicable guidance for using a proportional standard to make small
numbers determinations, NMFS either use a sliding scale that accounts
for the abundance of the species or stock or explain why it believes
that a single standard should be applied in all cases. The MMC offers
two examples, on either end of a spectrum, in illustrating its point.
First, MMC provides the example of a small population of marine
mammals, stating that ``taking the entire population may arguably
constitute a small number.'' Second, the MMC provides the example of a
large population of marine mammals, stating that ``certain types of
taking from large populations . . . push the limit of what reasonably
may be considered a small number.''
Response: NMFS disagrees that such a ``sliding scale'' is necessary
or appropriate. Under the ``one-third'' interpretation offered here,
and on which we base our small numbers analyses, take equating to
greater than one-third of the assumed individuals in the population
would not be considered small numbers, other than in certain
extenuating circumstances, such as the brief exposure of a single group
of marine mammals (as is authorized
[[Page 63302]]
herein for each applicant for such species as the killer whale). In
both of the MMC's examples, the MMC evidently reverts to an absolute
magnitude of the number on the ends of the spectrum, without regard for
the amount of individuals taken relative to the size of the population.
Historically, such an approach may have served as a meaningful limit on
actual removals from a population, prior to the development of the PBR
metric, but is not a useful consideration when evaluating takes by
Level B harassment from sound exposure. There is no meaningful way to
define what should be considered as a ``small'' number on the basis of
absolute magnitude, and the MMC offers no such interpretation or
justification.
Comment: The Associations provide a discussion of several topics
relating to ``small numbers'' and recommend that NMFS's small numbers
findings be thoroughly explained in the record for these actions.
Response: We agree that the basis for each finding should be
explained. Please see our revised explanation in ``Small Numbers
Analyses.''
Comment: Oceana claims that NMFS is in violation of the MMPA's
``small numbers'' requirement for a variety of reasons, including that
we authorize takes of the ``critically endangered'' North Atlantic
right whale and because we authorize takes of species for which there
are no available abundance estimates, and relates the potential
biological removal metric to the small numbers finding. Oceana and many
other commenters also make reference to a supposed ``Federal court
defined'' take limit of 12 percent of the appropriate stock abundance.
Response: The reference to a ``Federal court defined'' take limit
of 12 percent for small numbers likely comes from a 2003 district court
opinion (Natural Resources Defense Council v. Evans, 279 F.Supp.2d 1129
(N.D. Cal. 2003)). However, given the particular administrative record
and circumstances in that case, including the fact that our small
numbers finding for the challenged incidental take rule was based on an
invalid regulatory definition of small numbers, we view the district
court's opinion regarding 12 percent as dicta. Moreover, since that
time the Ninth Circuit Court of Appeals has upheld a small numbers
finding that was not based on a quantitative calculation. Center for
Biological Diversity v. Salazar, 695 F.3d 893 (9th Cir. 1012). Second,
while we agree that there are stocks for which no abundance estimate is
presented in NMFS's SARs, there are other available abundance estimates
for all impacted stocks. However, more importantly, there is no
requirement in the MMPA to authorize take only for stocks with
available abundance estimates, or even that a small numbers finding
must necessarily be based on a quantitative comparison to stock
abundance. We are required only to use the best available scientific
information in making a small numbers finding; this information may be
quantitative or qualitative, and may relate to relevant stock
information other than its overall abundance. Finally, the PBR metric
defines a level of removals from a population (i.e., mortality) that
would allow that population to remain at its optimum sustainable
population level or, if depleted, would not increase the population's
time to recovery by more than 10 percent. We reiterate that it is
inappropriate to make comparisons between takes by harassment and the
PBR value for any stock.
Comment: The MMC recommends that NMFS include both the numbers of
Level A and B harassment takes in its analysis of small numbers.
Response: We agree that this is appropriate and have done so.
Please see ``Small Numbers Analyses,'' later in this document, for full
detail.
Comment: TGS states that NMFS should better explain what it views
as the most appropriate abundance estimate for each stock.
Response: Please see our revised discussion of this topic in the
section entitled, ``Description of Marine Mammals in the Area of the
Specified Activities.''
Comment: Several commenters described problems with NMFS's proposed
approach to ensuring that actual take estimates remained below the
small numbers threshold proposed in our Notice of Proposed IHAs, i.e.,
a requirement for monthly interim reporting and a proposed process by
which companies would correct observations of marine mammals to obtain
an estimate of total takes.
Response: We agree with many of the points raised by commenters.
However, we discuss only the fundamental underlying issue here, i.e.,
our proposed small numbers analyses, which did not fully utilize all
the information that was available to refine the number of individuals
taken and prompted development of a proposed reporting scheme that was
roundly criticized. The small numbers analyses, described in our Notice
of Proposed IHAs, resulted in erroneous assessments that enumerated
take estimates for some applicants and some species would exceed the
proposed small numbers threshold. In order to ensure that the proposed
threshold would not be exceeded, we proposed that applicants would
submit monthly interim reports, including estimates of actual numbers
of takes (proposed to be produced via correction of numbers of observed
animals for certain biases using factors described in Carr et al.
(2011)), such that an authorization could be revoked if actual take
exceeded the proposed small numbers threshold. While we believe it is
appropriate to correct such observations in order to best understand
the actual number of takes (discussed elsewhere in these comment
responses), we agree that this proposal was inappropriate, i.e., that
NMFS should not issue an incidental take authorization for an activity
for which a small numbers threshold is expected to be exceeded.
Additionally, such an approach results in a clearly impracticable
situation for applicants, who commit substantial expenditure towards
conducting a given survey plan, but who then may be allowed to complete
only a portion of the plan.
In summary, as a result of our review of public comments, we re-
evaluated the relevant available information and produced revised small
numbers analyses (see ``Small Numbers Analyses,'' later in this
document). The revised small numbers analyses alleviated the need for
the proposed take reporting scheme and cap, which were also challenged
by multiple applicant and public commenters.
Mitigation, Monitoring, and Reporting
Comment: NRDC states that year-round closure is required in the
area off Cape Hatteras. This recommendation was also made by a group of
scientists from the University of North Carolina-Wilmington (D.A.
Pabst, W.A. McLellan, and A.C. Johnson; hereafter, ``Pabst et al.'').
Response: In this case, NRDC presents substantial evidence of the
year-round importance of this habitat to marine mammals (evidence cited
by NMFS in proposing the area as a seasonal closure); we agree that
this habitat is of year-round importance. We did not base the
development of this area as a seasonal restriction because of some
assumption that the area is only important for a portion of the year
(though the specific seasonal timing is based on increased density of
sperm whales; see ``Mitigation''). Rather, our development of this area
as a seasonal restriction was in consideration of practicability under
the MMPA's least practicable adverse impact standard. We believe NRDC's
comment inappropriately minimizes the element
[[Page 63303]]
of practicability in a determination of the measures that satisfy the
standard. In this case, the area is of critical interest to all
applicants--based on the dated historical survey information from the
region, this area is considered to potentially be most promising in
terms of hydrocarbon reserves. Therefore, an absolute proscription on
any given applicant's ability to collect data in this area would be
impracticable. In such a case where practicability concerns would
preclude inclusion of an otherwise valid measure, the measure must be
necessary to a finding of negligible impact (i.e., the negligible
impact determination cannot be made and the authorization may not be
issued absent the measure) in order to supersede the practicability
concerns. While NRDC presents substantial evidence of the importance of
this area for the marine mammals that use it, they do not grapple with
the practicability question or justify why the closure must be year-
round for a negligible impact determination to be made.
We disagree with NRDC's apparent contention that surveys conducted
in this region are likely to result in the death of resident beaked
whales. As we discussed in our Notice of Proposed IHAs, we recognize
the importance of the concepts described in Forney et al. (2017), i.e.,
that for resident animals, it is possible that displacement may lead to
effects on foraging efficiency that could impact individual vital
rates. However, no evidence is presented that severe acute impacts are
a reasonably anticipated outcome for surveys that will pass through
such habitat in a matter of days.
We also disagree with NRDC's summary dismissal of the benefit of
completely restricting survey activity in the habitat for a portion of
the year. The benefit of a restriction targeting resident animals is
sensibly scaled to the duration of the restriction and/or the timing of
the restriction in relation to reproductive behavior. However, we
believe that a full season without acute noise exposure, at minimum,
for those animals will provide meaningful benefit, including but not
limited to avoidance of the stress responses of concern to NRDC
elsewhere in their comments.
Comment: Regarding NMFS's proposed time-area restriction in waters
off Cape Hatteras, Pabst et al. state that recent data from acoustic
monitoring suggest that sperm whales are more abundant in this area
during winter.
Response: NMFS's initial proposal was to require implementation of
this restriction from July through September, in recognition of the
limited available visual survey data. As noted by commenters, visual
survey data do suggest that sperm whales are most common in the Cape
Hatteras region in summer (Roberts et al., 2016). The commenters go on
to note, however, that more recently available acoustic monitoring data
indicates that the highest number of sperm whale detections were made
in winter when visual survey effort was most limited (Stanistreet et
al., 2018). While we disagree with the commenters' larger point, i.e.,
that the ``Hatteras and North'' restriction should be in effect year-
round (addressed in previous comment response), we agree with their
interpretation of the data that sperm whales are more abundant in
winter. Upon review of this newly available data, we determined it
appropriate to revise the timing of this restriction to January through
March, as described in ``Mitigation.''
Comment: NRDC, the MMC, and multiple other commenters state that
NMFS must expand protection of North Atlantic right whale habitat. Many
commenters referred to the spatial aspect of the proposed restriction,
though some commenters also referred to the temporal aspect.
Response: We agree with the comments referencing the spatial
designation, and we are spatially expanding the seasonal restrictions
intended to protect right whale migratory habitat, in addition to
reproductive habitat and for general protection of right whales (or
requiring that comparable protection is achieved through implementation
of a NMFS-approved mitigation and monitoring plan at distances between
47-80 km offshore). Our determination in this regard and development of
this expanded protection are described in greater detail elsewhere in
these comment responses, as well as in the section entitled
``Mitigation.'' However, we disagree that the available evidence
supports expansion of this area temporally. Pabst et al., in
recommending a temporal expansion, reference an analysis of the
composition and distribution of individual right whale sightings
archived by the North Atlantic Right Whale Consortium from 1998 through
2015 performed by one of the comment authors. While this analysis (as
well as more recent acoustic monitoring data; e.g., Davis et al.
(2017)) suggests that right whales are present in the area in all
months of the year, it also shows that very few occurred outside of the
time window and outside of the year-round 30-km coastal restriction.
During this period, only five archived sightings occurred outside of
the November through April period and outside of 30 km from shore.
Further, it would be impracticable to completely close this area to
survey activity year-round. As we have acknowledged, it is possible
that whales will be present beyond this area, or that whales will be
present within this area but at times outside when migration is
expected to occur. However, we base the time-area restriction on our
best understanding of where and when most whales will be expected to
occur.
Comment: Several industry commenters provided comments regarding
NMFS's proposed exception to shutdown requirements for certain species
of dolphin. The Associations stated that, while they appreciate the
exception, it should apply to all dolphin species, regardless of
behavior. They add that no shutdowns for dolphins are warranted. CGG
also criticized the proposed behavior-based exception, instead
suggesting that a power-down requirement be applied as an alternative.
CGG favorably stated that such a requirement would ``allow for a
tolerable hole in the acquired seismic data and will not require the
vessel to immediately terminate the survey line and carry out a six
hour circle for infill'' and that use of power-downs rather than
shutdowns in these circumstances would result in substantial savings in
operating costs. TGS stated simply that NMFS ``should consider
clarifying and better addressing bow-riding dolphins'' and also
recommended that NMFS clarify and better define how to determine if
animals are stationary (in reference to NMFS's proposed behavior-based
requirements for dolphins).
Response: Following review of the available information and public
comments, NMFS agrees that a general exception to the standard shutdown
requirement is warranted for small delphinids, without regard to
behavior. We agree with TGS and other commenters that the intended
behavior-based exception was poorly defined. However, we do not agree
that the available evidence supports certain commenters' assertions
that seismic surveys do not have any adverse effects on dolphin
species. As discussed in ``Mitigation,'' auditory injury is not
expected for dolphins, but the reason for dolphin behavior around
vessels (when they are attracted) is not understood and cannot be
assumed to be harmless. In fact, the analyses of Barkaszi et al.
(2012), Stone (2015a), and Stone et al. (2017) show that dolphins do
avoid working vessels.
That said, the available information does not suggest that such
reactions are likely to have meaningful energetic
[[Page 63304]]
effects to individuals such that the effectiveness of such measures
outweighs the practicability concerns raised by commenters, in terms of
the operational costs as well as the difficulty of implementation. All
variations of a conditional shutdown exception proposed to date (by
either NMFS or BOEM) that include exceptions based on animal behavior
have been criticized, in part due to the subjective on-the-spot
decision-making such schemes would require of PSOs. NMFS finds these
criticisms warranted. If the mitigation requirements are not
sufficiently clear and objective, the outcome may be differential
implementation across surveys as informed by individual PSOs'
experience, background, and/or training. Therefore, the removal of such
measures for small delphinids is warranted in consideration of the
available information regarding the effectiveness of such measures in
mitigating impacts to small delphinids and the practicability of such
measures.
As noted above, one commenter suggested that a power-down
requirement would be practicable (though we note that this alternative
was offered against the backdrop of broader claims that no measures
should be required). We considered modifying the behavior-based
shutdown requirement contained in our proposed IHAs to CGG's suggested
general power down requirement. However, following consultation with
applicants and with BOEM, we determined that the circumstances of this
particular commenter (CGG) with regard to practicability may not be
broadly transferable, and that a power down requirement would
potentially lead to the need for termination of survey lines and infill
of the line where data were not acquired if a power down was performed
according to accepted practice, in which the power down condition would
last until the dolphin(s) are no longer observed within the exclusion
zone. As noted in our Notice of Proposed IHAs, the need to revisit
missed track line to reacquire data is likely to result in an overall
increase in the total sound energy input to the marine environment and
an increase in the total duration over which the survey is active in a
given area.
We disagree with comments that no shutdown requirements should
apply to any delphinid species, regardless of behavior. Here we refer
to ``large delphinids'' and ``small delphinids'' as shorthand for
generally deep-diving versus surface-dwelling/bow-riding groups,
respectively, although the important distinction is their dive behavior
rather than their size. As noted above, industry commenters have
asserted that no shutdown requirements are warranted for any species of
dolphin, stating that the best available science does not support
imposing such requirements. The comments acknowledge that small
delphinids are more likely to approach survey vessels than large
delphinids, but claim without supporting data that there is no evidence
that large delphinids will benefit from a shutdown requirement. In
contrast to the typical behaviors of (and observed effects on) the
small delphinid species group, the typical deep diving behavior of the
relatively rarely occurring large delphinid group of species makes
these animals potentially susceptible to interrupted/delayed feeding
dives, which can cause energetic losses that accrue to affect fitness.
As described in greater detail elsewhere in this Notice, there are
ample data illustrating the responses of deeper diving odontocetes
(including large delphinids) to loud sound sources (including seismic)
to include interrupted foraging dives, as well as avoidance with
increased speed and stroke rate, both of which may contribute to
energetic costs through lost feeding opportunities and/or increased
energy demands. Significant advances in study of the population
consequences of disturbance are informing our understanding of how
disturbances accrue to effects on individual fitness (reproduction and
survival) and ultimately to populations via the use of energetic
models, where data are available for a species, and expert elicitation
when data are still limited. The link between behavioral disturbance,
reduced energy budgets, and impacts on reproduction and survival is
clear, as is the value in reducing the probability or severity of these
behavioral disturbances where possible. Therefore, we find that there
is support for the effectiveness of the standard shutdown requirement
as applied to the large delphinid species group.
Further, the claim of industry commenters that shutdowns for these
deep-diving species would be impracticable was not accompanied by
supporting data. The data available to NMFS demonstrates that this
requirement is practicable. For example, Barkaszi et al. (2012)'s study
of observer data in the Gulf of Mexico from 2002-08 (1,440 bi-weekly
reports) shows that large delphinids were sighted on only 1.4% of
survey days, and that of these sightings, only 58% were within the 500-
meter exclusion zone.
Comment: Many commenters expressed concern regarding the efficacy
of the prescribed visual and acoustic monitoring methods, stating that
species could go undetected. Some commenters offer specific
recommendations for changes to staffing requirements. Finally, some of
these commenters state that NMFS should require operators to cease work
in low-visibility conditions, because of the difficulty in detecting
marine mammals in such conditions.
Response: While we disagree with some specific comments regarding
efficacy, we agree with the overall point that there are limitations on
what may reasonably be expected of either visual or acoustic
monitoring. While visual and acoustic monitoring effectively complement
each other, and acoustic monitoring is the most effective monitoring
method during periods of impaired visibility, there is no expectation
that such methods will detect all marine mammals present. In general,
commenters appear to misunderstand what we claim with regard to what
such monitoring may reasonably be expected to accomplish and/or the
extent to which we rely on assumptions regarding the efficacy of such
monitoring in reaching the necessary findings. We appropriately
acknowledge these limitations in prescribing these monitoring
requirements, while stating why we believe that visual and acoustic
monitoring, and the related protocols we have prescribed, are an
appropriate part of the suite of mitigation measures necessary to
satisfy the MMPA's least practicable adverse impact standard. However,
our findings of negligible impact and/or small numbers are in no way
conditioned on any presumption of monitoring efficacy. With regard to
specific staffing requirements, those prescribed herein are based on
typical best practices and on review of all available literature
concerning such practices. Commenters do not offer compelling
information that their proffered recommendations achieve the
appropriate balance between enhancement of monitoring effectiveness and
the costs (including both monetary costs as well as costs in terms of
berth space), and we retain the requirements originally specified.
Finally, any requirement to cease operations during low visibility
conditions, including at night, would not only be plainly
impracticable, it would also likely result in greater impacts to marine
mammals, as such a measure would require operations to continue for
roughly twice the time.
[[Page 63305]]
Such comments do not align with the principles we laid out in the
``Proposed Mitigation'' section of our Notice of Proposed IHAs, in
which we discussed the definitively detrimental effects of increased
time on the water and/or increased or unnecessary emission of sound
energy into the marine environment, versus the potential and uncertain
negative effect of proceeding to most efficiently conclude survey
activity by conducting operations even in low visibility conditions.
Comment: NRDC asserts that NMFS does not fulfill the MMPA's
requirement to prescribe mitigation achieving the ``least practicable
adverse impact'' to marine mammal habitat, and specifically notes that
NMFS does not separately consider mitigation aimed at reducing impacts
to marine mammal habitat, as the MMPA requires.
Response: We disagree. Our discussion of least practicable adverse
impact points out that because habitat value is informed by marine
mammal presence and use, in some cases there may be overlap in measures
for the species or stock and for use of habitat. Here we have
identified time-area restrictions based on a combination of factors
that include higher densities and observations of specific important
behaviors of the animals themselves, but also clearly reflect preferred
habitat. In addition to being delineated based on physical features
that drive habitat function (e.g., bathymetric features, among others),
the high densities and concentration of certain important behaviors
(e.g., feeding) in these particular areas clearly indicates the
presence of preferred habitat. Also, NRDC asserts that NMFS must
``separately'' consider measures aimed at marine mammal habitat. The
MMPA does not specify that effects to habitat must be mitigated in
separate measures, and NMFS has clearly identified measures that
provide significant reduction of impacts to both ``marine mammal
species and stocks and their habitat,'' as required by the statute.
Last, we note that NRDC acknowledges that NMFS's measures would reduce
impacts on ``acoustic habitat.''
Comment: The MMC recommended that, if NMFS is to require a time-
area restriction to protect spotted dolphins in shelf waters, the
restriction should be expanded from June through August to June through
September. This recommendation was made on the basis of spotted
dolphins likely being most abundant in this area during summer.
Similarly, TGS stated that NMFS should better support its determination
of seasonality for the proposed restriction.
Response: Following review of public comments, NMFS determined that
this proposed time-area restriction was unlikely to be effective in
accomplishing its intended purpose, while imposing practicability costs
on applicants. As explained in greater detail in the ``Mitigation''
section, we have eliminated this proposed requirement. Therefore, the
MMC's recommendation is no longer relevant.
Comment: NRDC states that NMFS must require larger buffer zones
around the required time-area restrictions. TGS stated that NMFS should
better support its choice of 10 km as a buffer distance.
Response: NRDC provides several reasons why they believe that the
required standard 10-km buffer zones are insufficient. NRDC claims
several supposed ``erroneous and misplaced assumptions'' in the sound
field modeling that informs our standard buffer zone, which we have
refuted elsewhere in these comment responses. More substantively, NRDC
returns again to its suggestion that a different threshold must be used
to represent Level B harassment. We have also addressed this comment
elsewhere. Here, we reiterate that BOEM's sound field modeling, which
was conducted in accordance with the best available scientific
information and methods, and which remains state-of-the-science,
indicates that the mean distance (considering 21 different scenarios
combining water depth, season, and bottom type) to the 160-dB isopleth
would be 6,838 m (range 4,959-9,122 m). Our required 10-km buffer is
appropriate in conservatively accounting for the potential for sound
exceeding the 160-dB isopleth.
Comment: NRDC stated that in order to adequately develop habitat-
based protections for marine mammals, NMFS should, in addition to
consideration of Roberts et al. (2016) and other relevant information,
follow certain guidelines to protect baleen whale stocks and other
marine mammals: (1) Continental shelf waters and waters 100 km seaward
of the continental slope; (2) waters within 100 km of all islands and
seamounts that rise within 500 m of the surface; and (3) high
productivity regions not included under the previous two guidelines.
Although NRDC's recommendation is unclear, we assume that the commenter
intends that we designate such areas as year-round closures to survey
activity.
Response: NMFS relied on the best available scientific information
(e.g., Stock Assessment Reports, Roberts et al., 2016, 2017; numerous
study reports from Navy-funded monitoring and research in the specific
geographic region) in assessing density, distribution, and other
information regarding marine mammal use of habitats in the study area.
In addition, NMFS consulted LaBrecque et al. (2015), which provides a
specific, detailed assessment of known Biologically Important Areas
(BIA). Although BIAs are not a regulatory designation, the assessment
is intended to provide the best available science to help inform
regulatory and management decisions about some, though not all,
important cetacean areas. BIAs, which may be region-, species-, and/or
time-specific, include reproductive areas, feeding areas, migratory
corridors, and areas in which small and resident populations are
concentrated. Because the BIA assessment may not include all important
cetacean areas, NMFS went beyond this evaluation in conducting a core
abundance analysis for all species on the basis of the Roberts et al.
(2016) cetacean density models (described in detail in our Notice of
Proposed IHAs). NMFS then weighed the results of the core abundance
analysis for each species in context of the anticipated effects of each
specified activity, other stressors impacting the species, and
practicability for the applicants in determining the appropriate suite
of time-area restrictions (see ``Mitigation''). Outside of these time-
area restrictions, NMFS is not aware of any evidence of other habitat
areas of particular importance, or of any compelling evidence that the
planned time-area restrictions should be modified in any way when
benefits to the species and practicability for applicants are
considered together.
Regarding NRDC's recommended guidelines, we disagree that these
would be appropriate for use in determining habitats for protection in
this circumstance. The guidelines come from a white paper
(``Identifying Areas of Biological Importance to Cetaceans in Data-Poor
Regions'') written by NMFS scientists for consideration in identifying
such areas in relation to mitigation development for the incidental
take rule governing the U.S. Navy's Surveillance Towed Array Sensor
System Low Frequency Active (SURTASS LFA) sonar activities, which was
applicable for much of the world's oceans, including in many so-called
data-poor areas. NMFS convened a panel of subject matter experts tasked
with helping to identify areas that met our criteria for offshore
biologically important areas (OBIAs) for marine mammals relevant to the
Navy's use of SURTASS LFA sonar, and the white paper offered guidance
on alternate
[[Page 63306]]
methods for considering data-poor areas, in view of the fact that data
on cetacean distribution or density do not exist for many areas of the
world's oceans. However, such is not the case for the specific
geographic region considered here. In fact, the white paper was
specifically developed to provide methods for data-poor areas as an
alternative to use of a global habitat model (Kaschner et al., 2006)
when such use was determined to result in both errors of omission
(exclusion of areas of known habitat) and commission (inclusion of
areas that are not known to be habitat). Here, we do not face the same
lack of data sufficient to inform the designation of appropriate
habitat-based restrictions. As described previously, we made use of
advanced habitat-based predictive density models, an existing
assessment of BIAs in the region, and a substantial body of data from
monitoring and research concerning cetacean distribution and habitat
use in sensitive areas of the region. Finally, were we to follow NRDC's
apparent recommendation in closing all of the areas covered by the
guidelines to survey activity, the resulting mitigation would not be
practicable for applicants, as a substantial portion of the planned
survey area would not be available.
Comment: NRDC states that NMFS should consider time-area closures
for additional species.
Response: We did consider habitat-based protections for species
additional to those discussed in the time-area restrictions section of
``Mitigation.'' For all affected species, we evaluated the
environmental baseline (i.e., other population-level stressors), the
nature and degree of effects likely to be the result of the specified
activities, and the information available to support the development of
appropriate time-area restrictions. We determined that the available
information supported development of the measures for the North
Atlantic right whale, sperm whales, beaked whales, and pilot whales.
For other species, context does not justify additional protections and/
or the available information does not support the designation of any
specific area for protection. NRDC suggests that such measures should
be developed for the humpback whale, sei whale, fin whale, and blue
whale. However, NRDC neither adequately justifies the recommendation,
offering only cursory reference to the ongoing humpback whale UME (but
not referencing the otherwise strong health of the West Indies DPS) and
summarily providing dire conclusions regarding the supposed effects on
all baleen whales, notwithstanding that at least two of these species
(the sei whale and blue whale) are anticipated as being unlikely to
experience any meaningful impacts from the specified activities. We
addressed NRDC's recommended use of a 2010 ``white paper'' in the
previous comment response; other than this apparent recommendation that
nearly the entirety of the survey area (e.g., continental shelf waters
and waters 100 km seaward of the continental slope; waters within 100
km of all islands and seamounts that rise within 500 m of the surface;
and high productivity regions not included under the previous two
guidelines) be declared as a protected area, NRDC offers no useful
recommendation as to the designation of protections for these species.
Our development of habitat-based protections was conducted
appropriately in light of relevant information regarding the
environmental baseline, expected effects of the specified activities,
and information regarding species use of the planned survey area.
Comment: NRDC states that our development of time-area restrictions
was performed inadequately, and Pabst et al. also challenged our use of
core abundance areas. TGS stated that we should better support our use
of the 25 percent core abundance area in determining the time-area
restrictions, and that we should better describe our consideration of
practicability.
Response: NRDC's primary complaint is that our use of the ``core
abundance area'' concept was inadequate, and other commenters appear to
believe that the core abundance area was the determining factor in the
delineation of restriction areas. These comments misapprehend our use
of core abundance areas, as we did not use the core abundance areas to
define habitat-based protections. To clarify, these core abundance
areas did not define the designated time-area restrictions, but rather
informed and supported our definition of the appropriate areas.
Further, there is no ``correct'' answer regarding the proportion of
core abundance that should inform development of habitat-based
protections. In part, our analysis of core abundance areas defined by
varying proportions of the population simply helped us to adequately
visualize areas within the specific geographic region that would
reasonably be expected to protect a substantive portion of the
population within a relatively well-defined area. In some cases, this
helped to confirm that stable habitat, i.e., habitat defined by
bathymetric features rather than dynamic oceanographic characteristics
and which would be expected to provide important habitat to certain
species, is indeed predicted to host high abundance of these species.
NRDC's comment regarding the sperm whale is illustrative. NRDC
refers simply to the 5 percent core abundance area for sperm whales as
``entirely inadequate.'' However, when analyzing multiple different
core abundance areas for the species, we find that it is predicted as
being broadly distributed over slope waters throughout much of the
year, i.e., there is little discrete habitat defined in a way that is
suitable for protection through a restriction on effort. Therefore, we
did not define the protections on the sole basis of the core abundance
area analysis. Rather, the core abundance area analysis helped to
highlight that sperm whales should be expected to be present year-round
in certain deepwater canyons (which also provide important habitat for
beaked whales); the spatial definition of these areas does not in fact
align with the predicted core abundance area, but rather with the
bathymetric features that provide the conditions that lead to the
predictions of high abundance in the first place, as is appropriate.
Separately, the 5 percent core abundance area highlighted that, in
contrast with the broad slope area over which sperm whales are
generally expected to occur, a discrete area off of Cape Hatteras
(i.e., ``The Point'') would be expected to provide attractive habitat
to sperm whales throughout the year, thus enabling us to include this
area, with other areas of importance for the sperm whale and other
species, in the conglomerate ``Hatteras and North'' (Area #4).
Our definition of the Hatteras and North area was primarily
informed by review of the available literature (as described in our
Notice of Proposed IHAs), which shows that, for example, beaked whales
are consistently present in particular waters of the shelf break region
at all times of year (e.g., McLellan et al., 2018; Stanistreet et al.,
2017); relatively high numbers of sperm whales are present off of Cape
Hatteras year-round (but particularly in the winter) (Stanistreet et
al., 2018); and pilot whales have a strong affinity for the shelf break
at Cape Hatteras and waters to the north (e.g., Thorne et al., 2017).
These findings provided a strong indication that the area should be
afforded some degree of protection in the form of restriction on
effort, while the core abundance analysis both supported these findings
and provided a more quantitative basis upon which to delineate the
specific area.
[[Page 63307]]
We also acknowledge the important role that practicability for
applicants plays in defining the appropriate suite of mitigation
requirements to satisfy the MMPA's least practicable adverse impact
standard, including design of habitat-based protections. Where a
negligible impact finding is not conditioned upon the implementation of
specific mitigation, prescription of mitigation must consider impacts
on practicability. As stated above, protection of additional habitat
for the sperm whale--given no basis on which to specify targeted
protections beyond those included herein--would necessarily involve
restricting access to large swaths of the specific geographic region.
Based on our understanding of applicant considerations, such
significant restrictions would likely lead to an applicant's
determination that the survey would not take place, as the return on
investment would not justify the expenditure, i.e., a clear-cut case of
a fatal practicability issue. In the absence of necessity (i.e., the
measure must be prescribed in order to make a finding of negligible
impact), it would not be permissible to require such stringent
restrictions.
NRDC goes on to cite ``important passive acoustic detections,
opportunistic sightings, and other data'' that we have supposedly
ignored, and cites the New York Bight (an area outside the specific
geographic region) as an area illustrating the supposed failure of the
density models to adequately highlight important habitat. NRDC also
references biologically important areas; as described later in this
document, we reviewed available information regarding BIAs (LaBrecque
et al., 2015) and there are no additional identified BIAs in the
region.
In summary, and contrary to NRDC's statements, we did not rely
exclusively on the core abundance analysis to define restriction areas.
While we may have inadvertently overemphasized this important aspect of
our process in the description provided in our Notice of Proposed IHAs,
we evaluated the available literature to inform our understanding of
rough areas suitable for protection (or characteristics that might
provide such areas), subsequently refining our analysis through use of
core abundance analysis to identify specific areas where features
expected to provide important habitat overlap with actual predictions
of high abundance and/or to refine the specific boundaries of areas
that the literature indicated to be of importance. We appropriately
based our definition of time-area restrictions on the available
literature as well as on our analysis of core abundance areas.
Comment: ION requests that we reconsider the proposed time-area
restrictions, based on a supposed lack of effects to right whales from
noise exposure, the lack of evidence for serious injury, death, or
stranding of beaked whales due to noise exposure from airgun surveys,
and the possibility that deepwater canyon closures could be timed to
coincide seasonally with the lowest density of sperm whales.
Response: We refer to the discussions provided in our Notice of
Proposed IHAs regarding ``Potential Effects of the Specified Activity
on Marine Mammals'' and detailing the rationale and basis for our
designation of time-area restrictions in ``Proposed Mitigation.'' We
stand by this information as supporting our assumptions regarding
likely effects of marine mammals and the need for such time-area
restrictions, and regarding the basis upon which we designated specific
restrictions. Specifically, we have designated the relatively small
deepwater canyon areas as year-round closures due to the likelihood
that they provide year-round habitat to beaked whales and possibly
sperm whales, while resulting in relatively minor practicability
impacts. ION claims that these three deepwater canyon closures would
result in ``large gaps in the seismic data acquired,'' but the map
provided as Figure 1 in ION's letter does not support this contention,
instead showing that only very small portions of several planned survey
lines pass through these areas.
Comment: CGG suggests that NMFS should evaluate observational data
submitted during the course of the survey and only require time-area
restrictions ``if potential significance of behavioral disruption and
potential for longer-term avoidance exists as a result of acoustic
exposure'' from the survey.
Response: We disagree that this would be the appropriate approach
to implementation of required restrictions. We also note that CGG
mistakenly states that distribution of some species targeted in our
design of restrictions is modeled through use of stratified models,
implying that not enough information exists on which to base such
restrictions. Our restriction areas target coastal bottlenose dolphins,
North Atlantic right whales, beaked whales, sperm whales, and pilot
whales, none of which are modeled through stratified models. More
importantly, the entire premise of time-area restrictions is that, on
the basis of a reasoned consideration of available information
regarding the anticipated impacts to the affected species or stocks,
their status, use of habitat, and practicability for applicants,
restrictions on survey effort to completely or partially avoid
sensitive habitat are appropriate. Moreover, it would not be
appropriate to allow the surveys to occur in those places, thereby
potentially allowing the impacts to sensitive habitat and/or disruption
of critical behaviors at important places and/or times, and expect that
observational data collected during the survey would adequately
indicate that the restriction should in fact be in place.
Comment: The Associations state that right whale dynamic management
areas (DMA) should not be used as operational restriction areas, and
that areas designated to identify the presence of right whales cannot
be used for multiple purposes, e.g., to reduce risk of ship strike and
to avoid harassment.
Response: The DMA concept recognizes that aggregations of right
whales can occur outside of areas and times where they predictably and
consistently occur, and it can be applied in various contexts. The DMA
construct is used to help reduce risk of ship strike for right whales
in association with NMFS's regulations for vessel speed limits in
prescribed ``seasonal management areas'' (73 FR 60173; October 10,
2008; extended by 78 FR 73726; December 9, 2013). In that regard, when
a specific aggregation of right whales is sighted, NMFS ``draws'' a
temporary zone (i.e., DMA) around the aggregation and alerts mariners.
DMAs are in effect for 15 days when designated and automatically expire
at the end of the period, but may be extended if whales are re-sighted
in the same area.
The DMA concept also was used between 2002 and 2009 to protect
unexpected aggregations of right whales that met an appropriate trigger
by temporarily restricting lobster trap/pot and anchored gillnet
fishing in the designated area (gear modifications have since replaced
those requirements).
As we have stated, it is critically important to avoid impacts to
right whales when possible and to minimize impacts when they do occur.
Because DMAs identify aggregations of right whales, it is appropriate
to restrict operations in these areas when DMAs are in effect. While we
acknowledge that this requirement will impose operational costs, if the
establishment of a DMA results in the need for a survey to temporarily
move to another location, such concerns are weighted appropriately here
in determining that this measure should be included in the suite of
mitigation necessary to achieve the least practicable adverse impact.
[[Page 63308]]
Comment: ION suggests that NMFS reconsider its position on use of
mitigation sources and power-downs, i.e., that NMFS should allow these
approaches to reduce operational impacts of required mitigation.
Response: We maintain that use of a ``mitigation source''--commonly
understood to involve firing of a single airgun for extended periods of
time to avoid the need for pre-clearance and/or ramp-up--is
inappropriate here. Our position on this is not based on a lack of
evidence that the mitigation source would be effective--indeed, we
agree that it is reasonable to assume some degree of efficacy for a
mitigation gun in providing a ``warning'' to marine mammals, as we
discuss in reference to use of ramp-up. Our determination is instead
based on a consideration that unnecessary introduction of sound energy
into the water, as occurs during use of a mitigation source, is
necessarily a deleterious impact, whereas the alternative--allowance of
start-up at times of poor visibility--may result in negative impacts to
individual marine mammals in the vicinity, but this is not certain.
Comment: Several commenters criticized our proposal to require
shutdowns upon detection of certain species or circumstances (e.g.,
beaked whales, right whales, whales with calves) at any distance. The
Associations suggest that such requirements are ``unreasonable''
because they require shutdowns ``for circumstances in which no Level A
or Level B harassment will occur,'' and recommend that such measures be
limited to power-down only for detections within 1,000 m. The
Associations also contend that these measures will have negative
impacts on the effectiveness of visual PSOs, stating that the result
would be that ``observers will be constantly monitoring an unlimited
zone, which [ . . . ] may undermine the effectiveness of their
monitoring of the 1,000 m zone.'' CGG makes similar claims, adding that
these measures would result in a substantial increase in operating
costs.
Response: We first note that the minimum Level B harassment zone
for any survey, in any location, would be beyond the likely detection
distance for visual observers, even under ideal conditions, e.g., the
smallest threshold radius out of 21 modeled scenarios from BOEM's PEIS
was almost 5 km. Therefore, the Associations' claim that shutdowns at
any distance would occur in circumstances where there is no harassment
is incorrect. Overall, we disagree with these comments, as well as
those specific comments we respond to below, which assert that such
measures are not warranted. In these cases, we have identified species
or circumstances with particular sensitivities (in conjunction with, in
some cases, a high magnitude of authorized take) for which we believe
it appropriate to minimize the duration and intensity of the behavioral
disruption, as well as to minimize the potential for auditory injury
(for low- and high-frequency cetaceans). However, while we also
disagree that trained, experienced professional PSOs would somehow
misunderstand our intent and spend undue time focusing observational
effort at distances beyond approximately 1,000 m from the acoustic
source (i.e., the zone within which we assume that monitoring is
typically focused, though not necessarily exclusively), in order to
ensure that this potential is minimized, and to alleviate to some
degree the operational cost associated with shutdowns at any distance,
we limit these shutdowns to within 1.5 km (versus at any distance). The
rationale for this distance is explained later in this document in
``Mitigation.''
Comment: Several commenters criticized the proposal to require
shutdowns based upon aggregations of six or more marine mammals in a
state of travel, stating that such a measure is ``vague and unbounded''
and would be impracticable due to the large number of shutdowns that
may result.
Response: We acknowledge that this measure, as described in our
Notice of Proposed IHAs, does not likely carry benefits commensurate
with the likely costs and is therefore impracticable. However, the
provided description was in error in that it inadvertently suggested
requirements beyond what we intended, i.e., we did not intend that this
measure would apply to species that commonly occur in large groups,
such as dolphins. We have modified this requirement to clearly state
that it applies only to aggregations of large whales (i.e., baleen
whales and sperm whales), and to eliminate the behavioral aspect of the
requirement, as recommended by commenters. Contrary to claims of
commenters, this measure (as clarified/revised) is warranted, in that
minimization of disruption for aggregations of resting and/or
socializing whales is important and also practicable. As described
above, the shutdown requirement is bounded by a maximum distance of 1.5
km.
Comment: Multiple industry commenters criticized the proposed
requirement for shutdowns upon observation of a diving sperm whale
centered on the forward track of the source vessel, stating that the
proposal was unclear and likely unworkable.
Response: We agree with commenters (though we disagree with
associated, unsupported statements regarding lack of effects to sperm
whales), and have removed this measure.
Comment: TGS stated that we should remove the requirement (specific
to TGS) to shut down upon observation of any fin whale.
Response: For reasons described in greater detail in the section
entitled ``Mitigation,'' we agree with this comment and have removed
the measure.
Comment: The Associations and other industry commenters state that
the requirement for shutdowns upon observation of large whales with
calf is not warranted and will be ``very impracticable because of the
large number of . . . shutdowns it will generate.''
Response: We disagree with these comments and retain this
requirement, albeit within the 1.5 km zone versus ``at any distance.''
As we discuss in the ``Mitigation'' section, groups of whales are
likely to be more susceptible to disturbance when calves are present
(e.g., Bauer et al., 1993), and disturbance of cow-calf pairs could
potentially result in separation of vulnerable calves from adults.
Separation, if it occurred, could be exacerbated by airgun signals
masking communication between adults and the separated calf (Videsen et
al., 2017). Absent separation, airgun signals can disrupt or mask
vocalizations essential to mother-calf interactions. Given the
consequences of potential loss of calves in context of ongoing UMEs for
multiple mysticete species, as well as the functional sensitivity of
the mysticete whales to frequencies associated with airgun survey
activity, we believe this measure is warranted by the MMPA's least
practicable adverse impact standard. Commenters provide no
justification for the claim that this measure will result in a large
number of shutdowns.
Comment: Several industry commenters also suggest that there is not
adequate justification for enhanced shutdown requirements for right
whales, beaked whales, or Kogia spp. These commenters all provide the
same points verbatim (paraphrased here): (1) Because the primary threat
facing right whales are entanglement with fishing gear and ship
strikes, enhanced shutdowns have no impact on the causes of right whale
decline; (2) while acknowledging that beaked whales are acoustically
sensitive, they claim that evidence does not exist regarding
[[Page 63309]]
sensitivity to airgun noise; and (3) Kogia spp. are grouped with high-
frequency cetaceans (and thus are subject to greater propensity for
auditory injury) on the basis of studies of harbor porpoise; therefore,
this classification is invalid.
Response: These claims lack merit, and we retain these requirements
(albeit within the 1.5 km zone versus ``at any distance''). We agree
that the primary threats to right whales are entanglement and ship
strike, but the deteriorating status of the population (discussed in
detail in the section entitled ``Description of Marine Mammals in the
Area of the Specified Activities'') indicates that impacts to
individual right whales should be avoided where possible and otherwise
minimized. The preponderance of evidence clearly demonstrates that
beaked whales are acoustically sensitive species. While beaked whale
stranding events have been associated with use of tactical sonar,
indicating that this specific noise source may be more likely to result
in behaviorally-mediated mortality, the lack of such association with
airgun surveys does not mean that beaked whales are less acoustically
sensitive to the noise source. The same holds for Kogia spp., albeit
with less evidence for these cryptic species. However, commenters'
claim regarding the classification of these species into the high-
frequency hearing group holds no merit. The best available scientific
information, while limited, indicates that these species are
appropriately classed as high-frequency cetaceans; commenters provide
no evidence to the contrary. While no data exists regarding Kogia spp.
hearing, these species were appropriately classified as high-frequency
cetaceans by Southall et al. (2007) on the basis of high-frequency
components of their vocalizations. More recent data confirms that Kogia
spp. use high-frequency clicks (Merkens et al., 2018) and, by
extension, that their classification as high-frequency cetaceans is
appropriate.
Comment: The MMC recommends that NMFS require shutdowns upon
acoustic detection of sperm whales, as is required for beaked whales
and Kogia spp.
Response: We agree with the MMC that shutdowns due to the presence
of sperm whales should not be limited to visual detection alone. This
recommendation appears to reflect some ambiguity in the description of
proposed mitigation provided in our Notice of Proposed IHAs, as it was
our intent to prescribe mitigation in accordance with this
recommendation. In conjunction with modifications to the proposed
mitigation (described in full in the section entitled ``Mitigation''),
we require that shutdowns be implemented upon confirmed acoustic
detection of any species (other than delphinids) within the relevant
exclusion zone.
Comment: NRDC and other commenters state that NMFS should prescribe
requirements for use of ``noise-quieting'' technology. NRDC elaborates
that in addition to requiring noise-quieting technology (or setting a
standard for ``noise output''), NMFS should ``prescribe targets to
drive research, development, and adoption of alternatives to
conventional airguns.''
Response: We agree with commenters that development and use of
quieting technologies, or technologies that otherwise reduce the
environmental impact of geophysical surveys, is a laudable objective
and may be warranted in some cases. However, here the recommended
requirements are either not practicable or are not within NMFS's
authority to require. To some degree, NRDC misunderstands our
discussion of this issue as presented in our Notice of Proposed IHAs.
We recognize, for example, that certain technologies, including the
Bolt eSource airgun, are commercially available, and that certain
techniques such as operation of the array in ``popcorn'' mode may
reduce impacts when viable, depending on survey design and objectives.
However, a requirement to use different technology from that planned or
specified by an applicant--for example, a requirement to use the Bolt
eSource airgun--would necessarily require an impracticable expenditure
to replace the airguns planned for use. NRDC offers no explanation for
why such an incredible cost imposition (in the millions of dollars)
should be considered practicable. Separately, NRDC appears to suggest
that NMFS must require or otherwise incentivize the development of
wholly new or currently experimental technologies. In summary, while we
agree that noise quieting technology is beneficial, the suggestions put
forward by commenters are either impracticable or outside the authority
provided to NMFS by the MMPA. However, NMFS would consider
participating in related efforts by NRDC or any other commenter
interested in these technologies.
Comment: NRDC claims that NMFS fails to consider mitigation to
reduce ship strike in right whale habitat. Separately, NRDC states that
NMFS should consider extending ship-speed requirements to all project
vessels within ``the North Atlantic right whale BIA.''
Response: We disagree with NRDC's contention. All project vessels
are required to adhere to vessel speed requirements. Indeed, the ship
speed restrictions in these IHAs are required of all vessels associated
with the surveys, regardless of length, whereas NMFS's ship speed
regulations apply only to vessels greater than 65 ft in length. We
agree with NRDC that ship speed requirements are warranted for all
project vessels in designated areas to minimize risk of strike for
right whales. However, we are unclear what specific area NRDC may mean
in referencing ``the North Atlantic right whale BIA.'' We require that
all project vessels adhere to a 10-kn speed restriction when in any
seasonal or dynamic management area, or critical habitat.
Comment: Industry commenters were unanimous in expressing concern
regarding required vessel strike avoidance mitigation measures, notably
regarding safety for operators. In particular, recommendations to
reduce speed and shift engines to neutral in certain circumstances were
viewed as unsafe for vessels towing gear.
Response: We agree with the concerns expressed by commenters, and
clarify that it was not our intent to require such measures for vessels
towing gear. Safety of human life is paramount, and where legitimate
concerns exist we agree that required mitigation must reflect such
concerns. We have revised our discussion of vessel strike avoidance
measures (see ``Mitigation'') to clarify that the primary requirements
are (1) all vessels must observe a 10-kn speed limit when transiting
right whale critical habitat, SMAs, or DMAs, and (2) all vessels must
observe separation distances identified in ``Mitigation,'' to the
extent practicable as relates to safety. These requirements do not
apply to the extent that a vessel is restricted in its ability to
maneuver and, because of the restriction, cannot comply or in any case
where compliance would create an imminent and serious threat to a
person or vessel. Speed alterations (aside from the 10-kn restriction,
when applicable), alterations in course, and shifting engines to
neutral are recommendations for how separation distances may be
achieved but are not requirements, and do not apply to any vessel
towing gear.
Comment: ION requests clarification on specific ``precautionary
measures'' required in order to minimize potential for vessel strike,
citing the following text from our Notice of Proposed IHAs: ``Vessel
speeds must also be reduced to 10 kn or less when mother/calf pairs,
pods, or large assemblages of cetaceans are observed near a vessel. A
single
[[Page 63310]]
cetacean at the surface may indicate the presence of submerged animals
in the vicinity of the vessel; therefore, precautionary measures should
be exercised when an animal is observed.''
Response: We clarify here that the latter statement, i.e.,
``precautionary measures should be exercised when an animal is
observed,'' carries no specific requirements. We intend only that
vessel operators act cautiously in accordance with established
practices of seamanship to avoid striking observed animals. The
requirements of the former statement, i.e., that vessel speeds must be
reduced when mother/calf pairs, pods, or large assemblages of cetaceans
are observed near a vessel, applies only to those specific
circumstances, i.e., not in speculative fashion if a single animal or
small group of animals is observed.
Comment: One individual stated that NMFS should require applicants
to monitor propagation conditions, suggesting that this could be
accomplished through use of conductivity, temperature, and depth (CTD)
measurement devices, and that vessels should not be allowed to operate
when propagation is ``exceptionally efficient.''
Response: The commenter does not specify what propagation
conditions should be considered ``exceptionally efficient.''
Regardless, we do not agree that such a requirement is warranted. The
sound field modeling conducted by BOEM and by the applicants that did
not make use of BOEM's modeling is purposely designed to reflect a
reasonable range of propagation conditions that are expected to be
encountered in the region. This does not mean that there will never be
unexpected conditions that may result in propagation beyond the modeled
distances. However, this potential does not require that operators
cease operating, as such a requirement would be fraught with
uncertainty and potentially result in significant additional operating
costs.
Comment: NRDC makes several recommendations relating to the use of
ramp-up.
Response: First, NRDC states that NMFS should require that ramp-up
occur over several stages in order to minimize exposure. We agree with
NRDC on this point, but are confused by the recommendation, which
appears to restate the ramp-up procedures described by NMFS in our
Notice of Proposed IHAs. Second, NRDC states that we ``should give
greater consideration to the requirements that apply after shutdown
periods.'' Again, we are unclear as to what NRDC's specific
recommendation is, but NRDC appears to criticize the allowance of an
array restart without ramp-up, assuming that constant observation has
been maintained without marine mammal detection. NRDC does not state
what they believe to be the problem with this allowance, and we believe
that it is consistent with current practice and appropriate in context
of the ``least practicable adverse impact.'' Finally, NRDC asserts that
the half-hour cutoff ``perversely incentivizes'' continuous firing to
avoid the delay of pre-clearance and ramp-up. This is another confusing
statement, as we explicitly disallow airgun firing when not necessary
for data acquisition, e.g., during line turns.
Comment: NRDC complains that the standard 500-m exclusion zone is
``plainly insufficient to prevent auditory injury,'' and many other
commenters echo these comments regarding the sufficiency of the
prescribed exclusion and buffer zones.
Response: We have acknowledged that some limited occurrence of
auditory injury is likely, for low- and high-frequency cetaceans.
However, we disagree that a larger standard exclusion zone is
warranted. As we explained in our Notice of Proposed IHAs, our intent
in prescribing a standard exclusion zone distance is to (1) encompass
zones for most species within which auditory injury could occur on the
basis of instantaneous exposure; (2) provide additional protection from
the potential for more severe behavioral reactions (e.g., panic,
antipredator response) for marine mammals at relatively close range to
the acoustic source; (3) provide consistency and ease of implementation
for PSOs, who need to monitor and implement the exclusion zone; and (4)
to define a distance within which detection probabilities are
reasonably high for most species under typical conditions. Our use of
500 m as the zone is not based directly on any quantitative
understanding of the range at which auditory injury would be entirely
precluded or any range specifically related to disruption of behavioral
patterns. Rather, we believe it is a reasonable combination of factors.
In summary, a practicable criterion such as this has the advantage of
familiarity and simplicity while still providing in most cases a zone
larger than relevant auditory injury zones, given realistic movement of
source and receiver. Increased shutdowns, without a firm idea of the
outcome the measure seeks to avoid, simply displace survey activity in
time and increase the total duration of acoustic influence as well as
total sound energy in the water (a goal we believe NRDC supports).
We agree that, when practicable, the exclusion zone should
encompass distances within which auditory injury is expected to occur
on the basis of instantaneous exposure. For high-frequency cetaceans,
these distances range from 355-562 m for four of the five applicants
(Table 5). For Spectrum, the predicted distance is significantly larger
(1,585 m). However, we require an extended exclusion zone of 1.5 km for
certain sensitive species, including Kogia spp. This means that only
one rarely occurring species (harbor porpoise), and for only one
applicant, is left unprotected from potential auditory injury in terms
of the prescribed distance of the exclusion zone. Moreover, it is
unlikely that harbor porpoise would even be detected at distances
greater than 500 m. Potential auditory injury for low-frequency
cetaceans is based on the accumulation of energy, and is therefore not
a straightforward consideration. For example, observation of a whale at
the distance calculated as being the ``injury zone'' does not
necessarily mean that the animal has in fact incurred auditory injury.
Rather, the animal would have to be at the calculated distance (or
closer) as the mobile source approaches, passes, and recedes from the
exposed animal, being exposed to and accumulating energy from airgun
pulses the entire time, as is implied by the name of the ``safe
distance'' methodology by which such zone distances are calculated.
Therefore, we disagree that it is sensible to create a larger exclusion
zone on the basis of the calculated injury zones (although we note that
the extended 1.5 km exclusion zone is required for right whales). We
also note that the maximum distance cited by NRDC (4,766 m) was an
error in our Notice of Proposed IHAs (corrected later in this document;
see ``Level A harassment'' in the ``Estimated Take'' section). In fact,
the calculated injury distances for two applicants are less than the
standard 500-m zone, while those calculated for the remaining three
applicants range from 757-951 m. In keeping with the four broad goals
outlined above, and in context of the information given here, our
standard 500-m exclusion zone is appropriate.
Comment: Several industry commenters criticized the requirement for
use of a buffer zone, in addition to the standard 500-m exclusion zone,
claiming in part that use of such a buffer is ``counterintuitive.''
[[Page 63311]]
Response: Having received multiple comments indicating confusion
regarding the proposed measure, we first clarify that the requirement
is for a 500-m buffer zone in addition to the 500-m standard exclusion
zone, i.e., total typical monitoring zone of 1,000 m, and that the
implementation of this requirement relates primarily to the pre-
clearance period, when the full 1,000-m zone must be clear of marine
mammals prior to beginning ramp-up. During full-power firing, the
buffer zone serves only as a sort of ``warning'' area, where the
observation of marine mammals should incite readiness to shut down,
should those animals enter the 500-m shutdown zone.
We disagree that this measure is counterintuitive, an assertion
based on the apparent sense that a larger zone should be in effect when
the array is firing and a smaller zone prior to firing. On the
contrary, we believe it important to implement a larger zone during
pre-clearance, when na[iuml]ve animals may be present and potentially
subject to severe behavioral reactions if airguns begin firing at close
range. While the delineation of zones is typically associated with
shutdown, the period during which use of the acoustic source is being
initiated is critical, and in order to avoid more severe behavioral
reactions it is important to be cautionary regarding marine mammal
presence in the vicinity when the source is turned on. This requirement
has broad acceptance in other required protocols: The Brazilian
Institute of the Environment and Natural Resources requires a 1,000-m
pre-clearance zone (IBAMA, 2005), the New Zealand Department of
Conservation requires that a 1,000-m zone be monitored as both a pre-
clearance and a shutdown zone for most species (DOC, 2013), and the
Australian Department of the Environment, Water, Heritage and the Arts
requires an even more protective scheme, in which a 2,000-m ``power
down'' zone is maintained for higher-power surveys (DEWHA, 2008).
Broker et al. (2015) describe the use of a precautionary 2-km exclusion
zone in the absence of sound source verification (SSV), with a minimum
zone radius of 1 km (regardless of SSV results). We believe that the
simple doubling of the exclusion zone required here is appropriate for
use as a pre-clearance zone.
Comment: In writing about the exception made for dolphins from the
shutdown requirements, NRDC states that ``more analysis is . . . needed
of the potential costs and benefits of excluding bow-riding dolphins
from the exclusion zone requirement.''
Response: We recognize the concerns raised by NRDC, and agree that
the reasons for bow-riding behavior are unknown and, further, that in
context of an active airgun array, the behavior cannot be assumed to be
harmless. However, dolphins have a relatively high threshold for the
onset of auditory injury and, for small delphinids, more severe adverse
behavioral responses are less likely given the evidence of purposeful
approach and/or maintenance of proximity to vessels with operating
airguns. With regard to the former point, Finneran et al. (2015)
exposed bottlenose dolphins to repeated pulses from an airgun and
measured no TTS. Therefore, the biological benefits of shutting down
for small delphinids are expected to be comparatively low, whereas, as
indicated through public comment on these proposed actions, the costs
of the shutdowns for survey operators is high. Therefore, our
consideration of this subject, as addressed in an earlier comment
response, indicates that a general (rather than behavior-based) small
delphinid exception to the standard shutdown requirement is an
appropriate part of the suite of mitigation measures necessary to
effect the least practicable adverse impact.
Comment: One individual stated that NMFS should require ``trackline
design'' that minimizes the potential for stranding, including by
requiring that companies run their nearshore lines at times of reduced
propagation efficiency.
Response: The commenter does not specify what is meant by
``nearshore,'' but we prescribe a year-round 30-km standoff from the
coast. We assume that 30 km is sufficient to accomplish the commenter's
objective in making the recommendation.
Comment: The Associations and other industry commenters raise
several concerns regarding the PSO requirements. These are: (1) Concern
regarding NMFS's requirement to review PSO qualifications and
associated potential for delay, with accompanying recommendation that
such reviews be ``bounded by some reasonably short time period, with
the default being that the observer is approved if NMFS fails to
respond within that time period''; (2) concern whether vessels can
``safely accommodate'' the number of PSOs required by NMFS's staffing
requirements; and (3) a claim that NMFS's requirements for PSOs will
result in labor shortages, and an accompanying recommendation that
these be ``guidelines'' rather than requirements.
Response: We agree with the first concern, and have clarified that
NMFS will have one week to review PSO qualifications (from the time
that NMFS confirms that adequate information has been submitted) and
either approve or reject a PSO. If NMFS does not respond within this
time, any PSO meeting the minimum requirements would automatically be
approved.
We disagree with the remainder of the statement. NMFS has evaluated
the appropriate PSO staffing requirements, as described in
``Mitigation,'' and we have determined that a minimum of two visual
PSOs must be on duty at all times during daylight hours in order to
adequately ensure visual coverage of the area around the source vessel.
Applicants must account for these requirements in selecting vessels
that will be suitable for their planned surveys. The Associations'
third point contains an apparent misconception, in that not all PSOs
must have a minimum of 90 days at-sea experience, with no more than 18
months elapsed since the conclusion of the relevant experience. As
described in our Notice of Proposed IHAs and herein, a minimum of one
visual PSO and two acoustic PSOs must have such experience (rather than
all PSOs). The Associations also apparently believe that a requirement
for professional biological observers to be ``trained biologists with
experience or training in the field identification of marine mammals,
including the identification of behaviors'' is a ``rigid restriction.''
We respectfully disagree with these claims, and note that no labor
shortage was experienced in the Gulf of Mexico during 2013-2015 when a
significantly greater amount of survey activity (i.e., as many as 30
source vessels) was occurring than is considered here, with
requirements similar to those described here. NMFS has discussed the
PSO requirements specified herein with the Bureau of Safety and
Environmental Enforcement (BSEE) and with third-party observer
providers; these parties have indicated that the requirements should
not be expected to result in any labor shortage.
Comment: The Associations recommend that passive acoustic
monitoring should be optional, citing operational costs. ION also
challenges the efficacy of PAM.
Response: We agree with the Associations that PAM complements
(rather than replaces) traditional visual monitoring. However, it is
now considered to be a critical component of real-time mitigation
monitoring in the majority of circumstances for deep penetration airgun
surveys. Acoustic monitoring supplants visual monitoring
[[Page 63312]]
during periods of poor visibility and supplements during periods of
good visibility. As such, we strongly disagree with the Associations'
outdated recommendation.
There are multiple explanations of how marine mammals could be in a
shutdown zone and yet go undetected by observers. Animals are missed
because they are underwater (availability bias) or because they are
available to be seen, but are missed by observers (perception and
detection biases) (e.g., Marsh and Sinclair, 1989). Negative bias on
perception or detection of an available animal may result from
environmental conditions, limitations inherent to the observation
platform, or observer ability. Species vary widely in the inherent
characteristics that inform expected bias on their availability for
detection or the extent to which availability bias is convolved with
detection bias (e.g., Barlow and Forney (2007) estimate probabilities
of detecting an animal directly on a transect line (g(0)), ranging from
0.23 for small groups of Cuvier's beaked whales to 0.97 for large
groups of dolphins). Typical dive times range widely, from just a few
minutes to more than 45 minutes for sperm whales (Jochens et al., 2008;
Watwood et al., 2006), while g(0) for cryptic species such as Kogia
spp. declines more rapidly with increasing Beaufort sea state than it
does for other species (Barlow, 2015). Barlow and Gisiner (2006)
estimated that when weather and daylight considerations were taken into
account, visual monitoring would detect fewer than two percent of
beaked whales that were directly in the path of the ship. PAM can be
expected to improve on that performance, and has been used effectively
as a mitigation tool by operators in the Gulf of Mexico since at least
2012.
We expect that PAM technology will continue to develop and improve,
and look forward in the near-term to the establishment of formal
standards regarding specifications for hardware, software, and operator
training requirements, under the auspices of the Acoustical Society of
America's (ASA) Accredited Standards Committee on Animal Bioacoustics
(ANSI S3/SC1/WG3; ``Towed Array Passive Acoustic Operations for
Bioacoustics Applications''). In short, we expect that PAM will
continue to be an integral component of mandatory mitigation monitoring
for deep penetration airgun surveys conducted in compliance with the
MMPA.
Comment: Several industry commenters expressed concern regarding
the potential for a large amount of shutdowns due to acoustic
detections of marine mammals in circumstances where the PAM operator is
unable to identify the detected species or is unable to determine the
location of the detected species in relation to the relevant exclusion
zone.
Response: NMFS recognizes these concerns, and appreciates the
comments; however, these potential outcomes would be contrary to NMFS's
intent in prescribing the use of PAM. Upon review of these comments, we
find that our description of PAM use was unclear and offer
clarification here. In the event of acoustic detection, shutdown must
be implemented only when the PAM operator determined, on the basis of
best professional judgment, that shutdown is required for the detected
species and that the species is likely within the relevant exclusion
zone. For example, although shutdown is required for certain genera of
large delphinids, we do not require shutdown upon acoustic detection of
any delphinid, as we do not expect that a PAM operator would likely be
capable of distinguishing a detected delphinid to species. As in all
cases, the detection would be communicated to visual observers (if on
duty); if the detected animal(s) are observed visually, shutdown may be
required depending on the species. Similarly, we clarify that the
shutdowns required upon observation of a large whale with calf or an
aggregation of six or more large whales are for visual observation
only; a PAM operator cannot be expected to determine on the basis of
acoustic detection whether a detected whale is with calf or is part of
an aggregation of six or more. Our intent is not to be overly
prescriptive, but to empower trained PAM operators to employ
professional judgment in determining whether shutdown is required in
the event of acoustic detection. That is, we neither require
precautionary shutdowns based on acoustic detections when either the
species or location cannot be determined, nor do we require absolute
certainty that the detected animal is within the relevant exclusion
zone if the PAM operator determines that the animal is most likely
within the zone on the basis of professional judgment.
Comment: ION recommends that NMFS extend the timeframe for
operation of the acoustic source during repair of the PAM system in the
event of malfunction.
Response: We believe that the requirements regarding conditions
under which a survey is allowed to continue in the event of PAM
malfunction are appropriate. These conditions, which are based on
established protocols required in New Zealand, have been implemented in
other locations with no known reports of undue hardship. We also note
that ION does not recommend any alternative. We will be open to
considering alternatives in the future, but retain these requirements
here.
Comment: ION questions NMFS's intentions regarding pre-clearance
requirements at nighttime, requesting that NMFS clarify that
observation with PAM satisfies this requirement.
Response: Ramp-up of the acoustic source, when necessary, may occur
at times of poor visibility (including nighttime), assuming that a pre-
clearance period has been observed. If the pre-clearance period occurs
at nighttime, the pre-clearance watch would be conducted only by the
acoustic observer. We clarify that, indeed, observation with PAM
satisfies the pre-clearance watch requirement at night.
Comment: TGS requests clarification of what they interpret as
contradictory instructions with regard to when visual observations must
occur.
Response: We clarify here that visual observation, i.e., two visual
PSOs on duty, is required during all daylight hours (30 minutes prior
to sunrise through 30 minutes following sunset, regardless of
visibility) when use of the acoustic source is planned, from 30 minutes
prior to ramp-up through one hour after ceasing use of the source (or
until 30 minutes after sunset). In addition, visual observation is to
occur 30 minutes prior to and during nighttime ramp-up.
Comment: NRDC suggests that NMFS should consider requiring use of
thermal detection as a supplement to visual monitoring.
Response: We appreciate the suggestion and agree that relatively
new thermal detection platforms have shown promising results. Following
review of NRDC's letter, we considered these and other supplemental
platforms as suggested. However, to our knowledge, there is no clear
guidance available for operators regarding characteristics of effective
systems, and the detection systems cited by NRDC are typically
extremely expensive, and are therefore considered impracticable for use
in most surveys. For example, one system cited by NRDC (Zitterbart et
al., 2013)--a spinning infrared camera and an algorithm that detects
whale blows on the basis of their thermal signature--was tested through
funding provided by the German government and, according to the author
at a 2015 workshop concerning mitigation and monitoring
[[Page 63313]]
for seismic surveys, the system costs hundreds of thousands of dollars.
We are not aware of its use in any commercial application. Further,
these systems have limitations, as performance may be limited by
conditions such as fog, precipitation, sea state, glare, water- and
air-temperatures and ambient brightness, and the successful results
obtained to date reflect a limited range of environmental conditions
and species. NRDC does not provide specific suggestions with regard to
recommended systems or characteristics of systems. We do not consider
requirements to use systems such as those recommended by NRDC to
currently be practicable.
Comment: Mysticetus, LLC (Mysticetus) recommends that all operators
be required to use a ``modern PSO software system'' for structured data
collection, real-time situational awareness and computerized mitigation
decision support. They also list their recommended minimum requirements
for a PSO software system. Mysticetus also recommends the creation of a
centralized cloud-based database to hold all PSO-gathered data from all
survey operations, and states that it should be a requirement of all
operators to have their PSO software automatically upload data to this
system on a regular schedule. Separately, we received a comment letter
from P.N. Halpin of Duke University's Marine Geospatial Ecology Lab;
the commenter provides support for the recommendation to create a
cloud-based storage system to store and provide public access to PSO
data and confirms that the OBIS-SEAMAP team has agreed in principle to
host and disseminate such a proposed database. Mysticetus goes on to
provide a number of detailed recommendations relating to how our notice
might describe the capabilities of a PSO software system, such as is
recommended for mandatory use, in relation to our proposed mitigation
and monitoring requirements.
Response: We appreciate commenters' careful attention to
improvement of required mitigation and monitoring and for their
recommendations. We also appreciate the capabilities of ``modern PSO
software'' described by Mysticetus, including the Mysticetus System
marketed by Mysticetus, LLC. We agree that such systems may be
advantageous for the operators, as well as for NMFS and for the public.
However, we disagree that NMFS must mandate that one specific software
system be used to accomplish the goals of the required mitigation and
monitoring, so long as the requirements for mitigation, monitoring, and
reporting are met.
Comment: The MMC stated that it supports our proposed requirement
relating to corrections of sightings data using detection
probabilities, in order to estimate numbers of actual incidents of
marine mammal take. However, the MMC also suggests that our proposed
use of Carr et al. (2011) is not the most appropriate source of such
probability values, and suggests that we instead base this approach on
Barlow (2015). In addition, the MMC points out that we did not
explicitly state that we also intend to account for unobserved areas,
and provided a recommended extrapolation method.
Response: We agree with the MMC's statements on this topic and
thank them for the helpful suggestions. Although, after review of
public comments, we do not require the applicants to conduct these
analyses themselves (described in greater detail in the section
entitled ``Monitoring and Reporting''), we intend to adopt the MMC's
recommended approach in performing this analysis. We will report these
corrected results in association with comprehensive reporting from the
applicants.
Comment: NRDC asserts that NMFS fails to prescribe requirements
sufficient to monitor and report takings of marine mammals, and further
draws a comparison to ``related compliance in the Gulf of Mexico''
where they state that ``BOEM is developing an adaptive management
program, which, beyond `the standard' safety zone monitoring and
reporting requirements, may include `visual or acoustic observation of
animals, new or ongoing research and data analysis, in situ
measurements of sound sources' . . . .'' Multiple commenters suggested
that monitoring plans should be designed and coordinated across
surveys. Commenters also noted that there are many research gaps that
need to be filled, and suggested that NMFS should include monitoring
requirements that fill those gaps--such as marine mammal habitat use,
abundance surveys, masking, mysticete hearing ranges, behavioral
response thresholds, ecosystem-wide impacts, and the efficacy of
mitigation measures. Specific recommendations included acoustic
receivers outside the survey area to allow for recording and assessment
before, during, and after surveys, as well as aerial surveys to
evaluate platform-based visual monitoring.
Response: Section 101(a)(5)(D) of the MMPA indicates that any
authorization NMFS issues shall include ``requirements pertaining to
the monitoring and reporting of such taking by harassment.'' This broad
requirement allows for a high degree of flexibility in what NMFS may
accept or include as a monitoring requirement, but is not specific in
identifying a threshold of what should be considered adequate
monitoring. Contrary to NRDC's comments, except for IHAs in Arctic
waters, NMFS's implementing regulations do not provide a specific
standard regarding what required monitoring and reporting measures
``must'' accomplish. However, they do direct that ``requests,'' i.e.,
the materials submitted by applicants, should include ``the suggested
means of accomplishing the necessary monitoring and reporting that will
result in increased knowledge of the species, the level of taking or
impacts on populations of marine mammals that are expected to be
present while conducting activities, and suggested means of minimizing
burdens by coordinating such reporting requirements with other schemes
already applicable to persons conducting such activity.'' NRDC further
extracts pieces of this language to suggest that in the case of these
five applicants, they are required to coordinate with each other's
monitoring efforts, ignoring the fact that the regulation points to
this coordination only in support of minimizing the burden on the
applicant and that it refers to coordination with ``schemes already
applicable to persons conducting such activity,'' of which there are
currently none. NRDC attempts to further this argument that
coordination across projects is required by statute by pointing to a
compliance scheme that they state is in development for the Gulf of
Mexico.
However, as described elsewhere in this document, section
101(a)(5)(D) of the MMPA indicates that the analysis, the findings, and
any requirements included in the development of an IHA pertain only to
the specified activity--specifically, NMFS is required to include the
``requirements pertaining to the monitoring and reporting of such
taking by harassment'' (referring to the taking authorized in the IHA).
Notably, section 101(a)(5)(A), which applies in the case of NMFS's
incidental take regulations for a specified activity for up to five
years, contains similar requirements, but the requirements apply to the
entirety of the activities covered under any incidental take
rulemaking. Indeed, NMFS's implementing regulations indicate that ``for
all petitions for regulations [ . . . ] applicants must provide the
information requested in 216.104 on their activity as a whole.''
Therefore, it
[[Page 63314]]
is appropriate that a monitoring plan developed in support of BOEM's
requested rulemaking to cover incidental take from activities covered
by their oil and gas program in the Gulf of Mexico would address, and
potentially coordinate across, multiple surveys.
Although the statute provides flexibility in what constitutes
acceptable monitoring and reporting measures (increased knowledge of
the species and the taking), NMFS's implementing regulations provide
additional guidance as to what an applicant should submit in their
requests, indicating ``Monitoring plans should include a description of
the techniques that would be used to determine the movement and
activities of marine mammals near the activity site(s) including
migration and habitat uses, such as feeding.'' We appreciate the
recommendations provided by the public, and agree that from a content
standpoint, many of the recommendations could qualify as appropriate
monitoring for any of these surveys. However, we note that many of the
monitoring recommendations require a scale of effort that is not
commensurate to the scale of either the underlying activities or the
anticipated impacts of the activities on marine mammals covered by any
single IHA. In other words, many of the recommended measures would
necessitate complex and expensive survey designs and methods that would
exceed the duration of any one activity (e.g., regular distribution and
abundance surveys, moored arrays for before/during/after studies) and/
or require levels of collaboration, planning and permitting (behavioral
response studies, aerial programs to evaluate mitigation effectiveness)
that are not reasonable in the context of an activity that consists of
one mobile source moving across a large area and that will last less
than a year and, further, is not appropriate in the context of the
comparatively smaller scale of total surveys in the Atlantic at the
current time.
Most importantly, regardless of whether other monitoring plans
would also suffice, we believe that the visual and acoustic monitoring
required for each of these surveys meets the MMPA requirement for
monitoring and reporting. NRDC implies that monitoring within 1 km of
the vessel is not useful or adequate. First, the required monitoring is
not limited to within a zone, as PSOs will record the required
information at whatever distance they can accurately collect it--and
past monitoring reports from similar platforms show useful data
collected beyond 1 km. Further, even if the PSOs cannot always see, or
acoustically monitor, the entire zone within which take is estimated to
occur, the data collected will still be both qualitatively and
quantitatively informative, as behaviors will be detectable within
these distances and there are accepted methods for extrapolating
sightings data to make inferences about larger areas. For these
surveys, the PSOs will gather detailed information on the marine
mammals both sighted and acoustically detected, their behaviors
(different facets detectable visually and acoustically) and locations
in relation to the sound source, and the operating status of any sound
sources--allowing for a better understanding of both the impacted
species as well as the taking itself.
Comment: Multiple commenters provided various comments concerning
transparency and data sharing with regard to data reported to NMFS.
Response: We agree with the overall point and will make all data
reported to NMFS in accordance with IHA requirements available for
public review following review and approval of reports by NMFS.
However, several commenters were apparently confused about the nature
of data required to be reported to NMFS and/or the mechanism of
reporting. For example, Oceana stated that NMFS should ``make the
seismic survey data available to industry, government, and the public
so that all stakeholders can make an informed cost-benefit analysis and
decide whether offshore drilling should be allowed. . . .'' However,
the survey data apparently referenced by Oceana is not required to be
provided by the applicants to NMFS, but is provided to BOEM. Oceana
also stated that NMFS should ``live stream data as often as possible as
well as archive the passive acoustic monitoring feed.'' Respectfully,
we are unclear as to what Oceana is referring to.
Comment: Several industry commenters took issue with the 15-km
buffers that NMFS understands will be required around National Marine
Sanctuaries.
Response: We described these requirements, which are a product of
discussions between BOEM and NOAA's Office of National Marine
Sanctuaries, in our Notice of Proposed IHAs solely for purposes of
thoroughness. Here, we clarify that this standoff distance is not a
requirement of NMFS and will not be included in any issued IHAs. As
such, criticisms of this requirement (which we expect to be included as
conditions in permits issued by BOEM) are not relevant here and we do
not respond to them.
Comment: A few commenters suggested that NMFS should fully
implement NOAA's Ocean Noise Strategy, which they interpreted as
meaning that certain knowledge gaps on marine mammals and noise must be
filled before NMFS may issue these IHAs. Another commenter said that to
help support implementation of the Ocean Noise Strategy Roadmap
(cetsound.noaa.gov/Assets/cetsound/documents/Roadmap/ONS_Roadmap_Final_Complete.pdf), the agencies (i.e., NOAA and BOEM)
should undertake efforts to evaluate impacts to marine mammal habitat
before, during, and after surveys occur.
Response: NMFS appreciates the support for the Ocean Noise Strategy
and agrees with the goal of focusing both agency science and agency-
required monitoring towards filling known gaps in our understanding of
the effects of noise on marine mammals wherever possible and
appropriate. The Ocean Noise Strategy does not mandate any specific
actions, though; rather, it directs NOAA to use our existing
authorities and capacities to focus on the management, science,
decision-making tool, and outreach goals outlined in the Roadmap. In
the case of MMPA incidental take authorizations, NMFS must abide by
statutory directive, and we have described above (both in comment
response and elsewhere in the body of this Notice) our rationale for
including the monitoring and reporting measures in these IHAs. In the
context of MMPA authorizations, it is typically easier to apply some of
the monitoring and research goals articulated in the Ocean Noise
Strategy through section 101(a)(5)(A) rulemaking, as the expanded scope
and longer duration of the coverage period are better suited to more
complex, large-scale, or expensive approaches (e.g., such as those
utilized for U.S. Navy training and testing incidental take
regulations).
National Environmental Policy Act
Comment: NRDC and Oceana provide a litany of complaints regarding
the sufficiency of BOEM's EIS and its suitability for supporting NMFS's
decision analysis, and state that NMFS must prepare a separate analysis
before taking action.
Response: Following independent evaluation of BOEM's EIS, and
review of public comments, NMFS determined BOEM's 2014 Final PEIS to be
comprehensive in analyzing the broad scope of potential survey
activities, and that the evaluation of the direct, indirect, and
cumulative impacts on the human environment, including the marine
environment, is adequate to
[[Page 63315]]
support NMFS's consideration for future issuance of ITAs to geophysical
companies and other potential applicants through tiering and
incorporation by reference. NMFS further determined that subsequent
issuance of ITAs for survey activities is likely to fall within the
scope of the analysis in the 2014 Final PEIS, particularly since the
impacts of the alternatives evaluated by BOEM (1) assess impact over a
much longer period of time (i.e., nine years) than is analyzed by NMFS
for any given ITA, (2) encompass many of the same factors NMFS
historically considered when reviewing ITAs for geophysical surveys or
related activity (i.e., marine mammal exposures, intensity of acoustic
exposure, monitoring and mitigation factors, and more), and (3) are
substantially the same as the impacts of NMFS's issuance of any given
ITA for take of marine mammals incidental to future applicants' survey
activities. The 2014 Final PEIS also addresses NOAA's required
components for adoption as it meets the requirements for an adequate
EIS under the CEQ regulations (40 CFR part 1500-1508) and NOAA
Administrative Order 216-6A and reflects comments and expert input
provided by NOAA as a cooperating agency. Therefore, NMFS subsequently
signed a Record of Decision that: (1) Adopted the Final PEIS to support
NMFS's analysis associated with issuance of ITAs pursuant to sections
101(a)(5)(A) or (D) of the MMPA and the regulations governing the
taking and importing of marine mammals (50 CFR part 216), and (2) in
accordance with 40 CFR 1505.2, announced and explained the basis for
NMFS's decision to review and potentially issue ITAs under the MMPA on
a case-by-case basis, if appropriate, guided by the analyses in the
Final PEIS and mitigation measures specified in BOEM's 2014 ROD.
However, following review of public comments, NMFS agrees with NRDC
and other commenters who suggested that it would not be appropriate for
NMFS to simply adopt BOEM's EIS (our stated approach in the Notice of
Proposed IHAs). Although we disagree with claims that the EIS is
deficient, it is appropriate to evaluate whether supplementation is
necessary. In so doing, we consider (1) whether new information not
previously considered in the EIS is now available; (2) whether that new
information may change the impact analysis contained in the EIS; and
(3) whether our impact conclusions may change as a result of the new
information and new impact analyses. However, we further consider that
the EIS was purposely developed so that additional information could be
included in subsequent NEPA evaluations. Because we determined that
relevant new information was in fact available, in addition to
applicant-specific details, we determined it appropriate to conduct a
supplemental Environmental Assessment.
NMFS determined that conducting NEPA review and preparing a tiered
EA is appropriate to analyze environmental impacts associated with
NMFS's issuance of separate IHAs to five different companies. NMFS
further determined that the issuance of these five IHAs are ``similar''
but not ``connected actions'' per 40 CFR 1508.25(a)(3) due to general
commonalities in geography, timing, and type of activity, which
provides a reasonable basis for evaluating them together in a single
environmental analysis. The EA also incorporates relevant portions of
BOEM's Final PEIS while focusing analysis on environmental issues
specific to the five IHAs. NMFS has completed the necessary
environmental analysis under NEPA.
Miscellaneous
Comment: Several commenters suggest that NMFS should require the
applicants to consolidate their surveys.
Response: Requiring individual applicants to alter their survey
objectives and/or design does not fall within NMFS's authority.
Moreover, though these multiple concurrent surveys are perceived as
``duplicative,'' they are in fact designed specifically to produce
proprietary data that satisfies the needs of survey funders. As is the
current practice in the Gulf of Mexico, it is within BOEM's
jurisdiction as the permitting agency to require permit applicants to
submit statements indicating that existing data are not available to
meet the data needs identified for the applicant's survey (i.e., non-
duplicative survey statement), but such requirements are not within
NMFS's purview. For example, NRDC claims erroneously that NMFS ``has
authority under the mitigation provision of the MMPA to consider
directing the companies to consolidate their surveys,'' placing such a
requirement under the auspices of practicability. Leaving aside that
directing any given applicant to abandon their survey plans would not
in fact be practicable, it is inappropriate to consider this suggested
requirement through that lens. Similarly, the MMC vaguely references
section 101(a)(5)(A)(i)(II)(aa) in stating that NMFS is provided
authority to require such consolidation--we assume that MMC intended to
reference the parallel language at section 101(a)(5)(D)(ii)(I), which
states only that NMFS shall prescribe the ``means of effecting the
least practicable impact on such species or stock and its habitat.''
NMFS considers the specified activity described by an applicant in
reviewing a request for an incidental take authorization; nothing in
the statute provides authority to direct consolidation of independent
specified activities (regardless of any presumption of duplication,
about which NMFS is not qualified to judge).
The MMC specifically cites a number of collaborative surveys
conducted in foreign waters, and recommends that NMFS ``work with
BOEM'' to require such collaboration. However, MMC provides no useful
recommendations as to how such collaboration might be achieved. Given
the absence of appropriate statutory authority, we recommend that the
MMC itself undertake to foster such collaboration between geophysical
data acquisition companies and relevant Federal agencies as it deems
necessary to protect and conserve marine mammals. NMFS looks forward to
joining in such an MMC-led collaboration, as appropriate.
We also note that industry commenters stated, anticipating
suggestions of this sort, that such recommendations ``are based upon a
substantial misunderstanding of important technical, operational, and
economic aspects of seismic surveying.'' These commenters also noted
that, based on the findings of an expert panel recently convened by
BOEM to study the issue of duplicative surveys (see Appendix L in BOEM,
2017), none of the surveys considered here would meet the definition
established for a ``duplicate'' survey.
Comment: NRDC contends that NMFS must consider a standard requiring
analysis and selection of minimum source levels. In furtherance of this
overall quieting goal, NRDC also states that NMFS should consider
requiring that all vessels employed in the survey activities undergo
regular maintenance to minimize propeller cavitation and be required to
employ the best ship-quieting designs and technologies available for
their class of ship, and that we should require these vessels to
undergo measurement for their underwater noise output.
Response: An expert panel convened by BOEM to determine whether it
would be feasible to develop standards to determine a lowest
practicable source level has determined that it would not be reasonable
or practicable to develop such metrics (see Appendix L in BOEM,
[[Page 63316]]
2017). We appreciate that NRDC disagrees with the panel's findings, but
we do not believe it appropriate to address these grievances to NMFS.
NRDC further claims that NMFS's deference to the findings of an expert
panel convened specifically to consider this issue is ``arbitrary under
the MMPA.'' The bulk of NRDC's comment appears to be addressed to BOEM,
and we encourage NRDC to engage with BOEM regarding these supposed
shortcomings of the panel's findings. The subject matter is outside
NMFS's expertise, and we have no basis upon which to doubt the panel's
published findings. We decline to address here the ways in which NRDC
claims that BOEM misunderstood the issue.
With regard to the recommended requirements to measure or control
vessel noise, or to make some minimum requirements regarding the design
of vessels used in the surveys, we disagree that these requirements
would be practicable. While we agree that vessel noise is of concern in
a cumulative and chronic sense, it is not of substantial concern in
relation to the MMPA's least practicable adverse impact standard, given
the few vessels used in any given specified activity. NMFS looks
forward to continued collaboration with NRDC and others towards ship
quieting.
Description of Marine Mammals in the Area of the Specified Activities
We refer readers to NMFS's Stock Assessment Reports (SAR;
www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments), species descriptions provided on NMFS's website
(www.fisheries.noaa.gov/find-species), and to the applicants' species
descriptions (Sections 3 and 4 of the applications). These sources
summarize available information regarding physical descriptions, status
and trends, distribution and habitat preferences, behavior and life
history, and auditory capabilities of the potentially affected species,
and are not reprinted here.
Table 2 lists all species with expected potential for occurrence in
the mid- and south Atlantic and summarizes information related to the
population or stock, including potential biological removal (PBR). For
taxonomy, we follow Committee on Taxonomy (2017). PBR, defined by the
MMPA as the maximum number of animals, not including natural
mortalities, that may be removed from a marine mammal stock while
allowing that stock to reach or maintain its optimum sustainable
population, is considered in concert with known sources of ongoing
anthropogenic mortality (as described in NMFS's SARs). For status of
species, we provide information regarding U.S. regulatory status under
the MMPA and ESA.
Marine mammal abundance estimates presented in this document
represent the total number of individuals that make up a given stock or
the total number estimated within a particular study area. NMFS's stock
abundance estimates for most species represent the total estimate of
individuals within the geographic area, if known, that comprises that
stock. For some species, this geographic area may extend beyond U.S.
waters. Survey abundance (as compared to stock or species abundance) is
the total number of individuals estimated within the survey area, which
may or may not align completely with a stock's geographic range as
defined in the SARs. These surveys may also extend beyond U.S. waters.
In some cases, species are treated as guilds. In general ecological
terms, a guild is a group of species that have similar requirements and
play a similar role within a community. However, for purposes of stock
assessment or abundance prediction, certain species may be treated
together as a guild because they are difficult to distinguish visually
and many observations are ambiguous. For example, NMFS's Atlantic SARs
assess Mesoplodon spp. and Kogia spp. as guilds. Here, we consider
pilot whales, beaked whales (excluding the northern bottlenose whale),
and Kogia spp. as guilds. In the following discussion, reference to
``pilot whales'' includes both the long-finned and short-finned pilot
whale, reference to ``beaked whales'' includes the Cuvier's,
Blainville's, Gervais, Sowerby's, and True's beaked whales, and
reference to ``Kogia spp.'' includes both the dwarf and pygmy sperm
whale.
Thirty-four species (with 39 managed stocks) are considered to have
the potential to co-occur with the planned survey activities. Species
that could potentially occur in the survey areas but are not expected
to have reasonable potential to be harassed by any survey are omitted
from further analysis. These include extralimital species, which are
species that do not normally occur in a given area but for which there
are one or more occurrence records that are considered beyond the
normal range of the species. Extralimital species or stocks unlikely to
co-occur with survey activity include nine estuarine bottlenose dolphin
stocks, four pinniped species, the white-beaked dolphin (Lagenorhynchus
albirostris), and the beluga whale (Delphinapterus leucas). For
detailed discussion of these species, please see our Federal Register
Notice of Proposed IHAs (82 FR 26244; June 6, 2017). In addition, the
West Indian manatee (Trichechus manatus latirostris) may be found in
coastal waters of the Atlantic. However, manatees are managed by the
U.S. Fish and Wildlife Service and are not considered further in this
document. All managed stocks in this region are assessed in NMFS's U.S.
Atlantic SARs. All values presented in Table 2 are the most recent
available at the time of publication and are available in the 2017 SARs
(Hayes et al., 2018a) and draft 2018 SARs (available online at:
www.fisheries.noaa.gov/national/marine-mammal-protection/draft-marine-mammal-stock-assessment-reports).
Table 2--Marine Mammals Potentially Present in the Vicinity of Survey Activities
--------------------------------------------------------------------------------------------------------------------------------------------------------
NMFS stock
ESA/ MMPA abundance (CV, Predicted mean Predicted Annual M/
Common name Scientific name Stock status; Nmin, most recent (CV)/maximum abundance PBR SI (CV)
strategic (Y/ abundance survey) abundance \3\ outside \5\
N) \1\ \2\ EEZ \4\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Order Cetartiodactyla--Cetacea--Superfamily Mysticeti (baleen whales)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Balaenidae:
North Atlantic right whale. Eubalaena Western North E/D; Y 451 (n/a; 445; n/ 394 (0.07) *..... 1 0.9 5.56
glacialis. Atlantic (WNA). a).
Family Balaenopteridae
(rorquals):
Humpback whale............. Megaptera Gulf of Maine.... -; N 896 (n/a; 896; 1,637 (0.07) */ 8 14.6 9.8
novaeangliae 2015). 1,994.
novaeangliae.
[[Page 63317]]
Minke whale................ Balaenoptera Canadian East -; N 2,591 (0.81; 2,112 (0.05) */ 929 14 7.5
acutorostrata Coast. 1,425; 2011). 2,431.
acutorostrata.
Bryde's whale.............. B. edeni brydei.. None defined \6\. -; n/a n/a.............. 7 (0.58)/n/a..... 7 n/a n/a
Sei whale.................. B. borealis Nova Scotia...... E/D; Y 357 (0.52; 236; 717 (0.30) */ 46 0.5 0.6
borealis. 2011). 1,519.
Fin whale.................. B. physalus WNA.............. E/D; Y 1,618 (0.33; 4,633 (0.08)/ 44 2.5 2.5
physalus. 1,234; 2011). 6,538.
Blue whale................. B. musculus WNA.............. E/D; Y Unknown (n/a; 11 (0.41)/n/a.... 4 0.9 Unk.
musculus. 440; n/a).
--------------------------------------------------------------------------------------------------------------------------------------------------------
Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Physeteridae:
Sperm whale................ Physeter North Atlantic... E/D; Y 2,288 (0.28; 5,353 (0.12)/ 2,456 3.6 0.8
macrocephalus. 1,815; 2011). 7,193.
Family Kogiidae:
Pygmy sperm whale.......... Kogia breviceps.. WNA.............. -; N 3,785 (0.47; 678 (0.23)/n/a 428 21 3.5
2,598; 2011) \7\. \7\. (1.0)
Dwarf sperm whale.......... K. sima.......... WNA.............. -; N
Family Ziphiidae (beaked
whales):
Cuvier's beaked whale...... Ziphius WNA.............. -; N 6,532 (0.32; 14,491 (0.17)/ 9,426 50 0.4
cavirostris. 5,021; 2011). 16,635 \7\.
Gervais beaked whale....... Mesoplodon WNA.............. -; N 7,092 (0.54; 46 0.2
europaeus. 4,632; 2011) \7\.
Blainville's beaked whale.. M. densirostris.. WNA.............. -; N
Sowerby's beaked whale..... M. bidens........ WNA.............. -; N
True's beaked whale........ M. mirus......... WNA.............. -; N
Northern bottlenose whale.. Hyperoodon WNA.............. -; N Unknown.......... 90 (0.63)/n/a.... 11 Undet. 0
ampullatus.
Family Delphinidae:
Rough-toothed dolphin...... Steno bredanensis WNA.............. -; N 136 (1.0; 67; 532 (0.36)/n/a... 313 0.7 0
2016).
Common bottlenose dolphin.. Tursiops WNA Offshore..... -; N 77,532 (0.40; 97,476 (0.06)/ 5,280 561 39.4
truncatus WNA Coastal, D; Y 56,053; 2011). 144,505 \7\. 48 (0.29)
truncatus. Northern 6,639 (0.41; 6.1
Migratory. 4,759;. (0.32)-1
2016)............ 3.2
(0.22)
WNA Coastal, D; Y 3,751 (0.60; 23 0-14.3
Southern D; Y 2,353; 2016). 46 (0.31)
Migratory. 6,027 (0.34; 1.4-1.6
WNA Coastal, 4,569; 2016).
South Carolina/
Georgia.
WNA Coastal, D; Y 877 (0.49; 595; 6 0.6
Northern Florida. D; Y 2016). 9.1 0.4
WNA Coastal, 1,218 (0.35; 913;
Central Florida. 2016).
Clymene dolphin............ Stenella clymene. WNA.............. -; N 6,086 (0.93; 12,515 (0.56)/n/a 11,503 Undet. 0
3,132; 1998) \8\.
Atlantic spotted dolphin... S. frontalis..... WNA.............. -; N 44,715 (0.43; 55,436 (0.32)/ 7,339 316 0
31,610; 2011). 137,795.
Pantropical spotted dolphin S. attenuata WNA.............. -; N 3,333 (0.91; 4,436 (0.33)/n/a. 2,781 17 0
attenuata. 1,733; 2011).
Spinner dolphin............ S. longirostris WNA.............. -; N Unknown.......... 262 (0.93)/n/a... 184 Undet. 0
longirostris.
Striped dolphin............ S. coeruleoalba.. WNA.............. -; N 54,807 (0.3; 75,657 (0.21)/ 15,166 428 0
42,804; 2011). 172,158.
Common dolphin............. Delphinus delphis WNA.............. -; N 70,184 (0.28; 86,098 (0.12)/ 3,154 557 406
delphis. 55,690; 2011). 129,977. (0.10)
Fraser's dolphin........... Lagenodelphis WNA.............. -; N Unknown.......... 492 (0.76)/n/a... 474 Undet. 0
hosei.
Atlantic white-sided Lagenorhynchus WNA.............. -; N 48,819 (0.61; 37,180 (0.07)/ 368 304 57
dolphin. acutus. 30,403; 2011). 59,008. (0.15)
Risso's dolphin............ Grampus griseus.. WNA.............. -; N 18,250 (0.46; 7,732 (0.09)/ 1,060 126 49.9
12,619; 2011). 18,377. (0.24)
Melon-headed whale......... Peponocephala WNA.............. -; N Unknown.......... 1,175 (0.50)/n/a. 1,095 Undet. 0
electra.
Pygmy killer whale......... Feresa attenuata. WNA.............. -; N Unknown.......... n/a.............. n/a Undet. 0
False killer whale......... Pseudorca WNA.............. -; Y 442 (1.06; 212; 95 (0.84)/n/a.... 35 2.1 Unk.
crassidens. 2011).
Killer whale............... Orcinus orca..... WNA.............. -; N Unknown.......... 11 (0.82)/n/a.... 4 Undet. 0
Short-finned pilot whale... Globicephala WNA.............. -; N 28,924 (0.24; 18,977 (0.11)/ 2,258 236 168
macrorhynchus. 23,637; 2016). 35,715 \6\. (0.13)
Long-finned pilot whale........ G. melas melas... WNA.............. -; N 5,636 (0.63; 35 27
3,464; 2011). (0.18)
[[Page 63318]]
Family Phocoenidae (porpoises):
Harbor porpoise............ Phocoena phocoena Gulf of Maine/Bay -; N 79,833 (0.32; 45,089 (0.12) */ 91 706 255
phocoena. of Fundy. 61,415; 2011). 50,315. (0.18)
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Endangered Species Act (ESA) status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-) indicates that the species is not listed
under the ESA or designated as depleted under the MMPA. Under the MMPA, a strategic stock is one for which the level of direct human-caused mortality
exceeds PBR or which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed
under the ESA is automatically designated under the MMPA as depleted and as a strategic stock.
\2\ NMFS marine mammal stock assessment reports online at: www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments. CV
is coefficient of variation; Nmin is the minimum estimate of stock abundance. In some cases, CV is not applicable. For the right whale, the best
abundance value is based on a model of the sighting histories of individually identifiable animals (as of October 2017). The model of these histories
produced a median abundance value of 451 whales (95 percent credible intervals 434-464). The minimum estimate of 440 blue whales represents
recognizable photo-identified individuals.
\3\ This information represents species- or guild-specific abundance predicted by habitat-based cetacean density models (Roberts et al., 2016). For the
North Atlantic right whale, we report the outputs of a more recently updated model (Roberts et al., 2017). These models provide the best available
scientific information regarding predicted density patterns of cetaceans in the U.S. Atlantic Ocean, and we provide the corresponding mean annual and
maximum monthly abundance predictions. Total abundance estimates were produced by computing the mean density of all pixels in the modeled area and
multiplying by its area. Roberts et al. (2016) did not produce a density model for pygmy killer whales off the east coast. For those species marked
with an asterisk, the available information supported development of either two or four seasonal models; each model has an associated abundance
prediction. Here, we report the maximum predicted seasonal abundance.
\4\ The density models used to predict acoustic exposures (e.g., Roberts et al., 2016) provide abundance predictions for the area within the U.S. EEZ.
However, the model outputs were also extrapolated to the portion of the specific geographic region outside the EEZ in order to predict acoustic
exposures in that area (i.e., from 200 nmi to 350 nmi offshore). Therefore, we calculated corresponding seasonal abundance estimates for this region.
The maximum seasonal abundance estimate is reported.
\5\ These values, found in NMFS's SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined (e.g.,
commercial fisheries, ship strike). Annual M/SI often cannot be determined precisely and is in some cases presented as a minimum value or range. A CV
associated with estimated mortality due to commercial fisheries is presented in some cases.
\6\ Bryde's whales are occasionally reported off the southeastern U.S. and southern West Indies. NMFS defines and manages a stock of Bryde's whales that
is resident in the northern Gulf of Mexico, but does not define a separate stock in the Atlantic Ocean.
\7\ Abundance estimates are in some cases reported for a guild or group of species when those species are difficult to differentiate at sea. Similarly,
the habitat-based cetacean density models produced by Roberts et al. (2016) are based in part on available observational data which, in some cases, is
limited to genus or guild in terms of taxonomic definition. NMFS's SARs present pooled abundance estimates for Kogia spp. and Mesoplodon spp., while
Roberts et al. (2016) produced density models to genus level for Kogia spp. and Globicephala spp. and as a guild for most beaked whales (Ziphius
cavirostris and Mesoplodon spp.). Finally, Roberts et al. (2016) produced a density model for bottlenose dolphins that does not differentiate between
offshore and coastal stocks.
\8\ NMFS's abundance estimates for the Clymene dolphin is greater than eight years old and not considered current. PBR is therefore considered
undetermined for this stock, as there is no current minimum abundance estimate for use in calculation. We nevertheless present the most recent
abundance estimate.
For the majority of species potentially present in the specific
geographic region, NMFS has designated only a single generic stock
(e.g., ``western North Atlantic'') for management purposes. This
includes the ``Canadian east coast'' stock of minke whales, which
includes all minke whales found in U.S. waters. For the humpback and
sei whales, NMFS defines stocks on the basis of feeding locations,
i.e., Gulf of Maine and Nova Scotia, respectively. However, our
reference to humpback whales and sei whales in this document refers to
any individuals of the species that are found in the specific
geographic region. These individuals may be from the same breeding
population (e.g., West Indies breeding population of humpback whales)
but visit different feeding areas. For the bottlenose dolphin, NMFS
defines an oceanic stock and multiple coastal stocks.
North Atlantic Right Whale--We provide additional discussion of the
North Atlantic right whale in order to address the current status of
the species, which has deteriorated since publication of our Notice of
Proposed IHAs. The North Atlantic right whale was severely depleted by
historical whaling, and was originally listed as endangered under the
ESA in 1970. The right whale's range historically extended to the
eastern North Atlantic, as well as the Denmark Strait and waters south
of Greenland. However, sightings of right whales beyond their current
western North Atlantic distribution are rare and the eastern North
Atlantic population may be functionally extinct (Kraus and Rolland,
2007; Best et al., 2001). In the western North Atlantic, a median
abundance value of 451 whales in October 2017 (as reported in NMFS's
draft 2018 SARs and Table 2) based on a Bayesian mark-recapture open
population model, which accounts for individual differences in the
probability of being photographed (95 percent credible intervals 434-
464, Pace et al., 2017). Accurate pre-exploitation abundance estimates
are not available for either population of the species. The western
population may have numbered fewer than 100 individuals by 1935, when
international protection for right whales came into effect (Kenney et
al., 1995).
Modeling suggests that in 1980, females had a life expectancy of
approximately 52 years of age (twice that of males at the time)
(Fujiwara and Caswell, 2001). However, due to reduced survival
probability, in 1995 female life expectancy was estimated to have
declined to approximately 15 years, with males having a slightly higher
life expectancy into the 20s (Fujiwara and Caswell, 2001). A recent
study demonstrated that females have substantially higher mortality
than males (Pace et al., 2017), and as a result, also have
substantially shorter life expectancies.
Gestation is approximately one year, after which calves typically
nurse for around a year (Kenney, 2009; Kraus et al., 2007; Lockyer,
1984). After weaning calves, females typically undergo a `resting' year
before becoming pregnant again, presumably because they need time to
recover from the energy deficit experienced during lactation (Fortune
et al., 2012, 2013; Pettis et al., 2017b). From 1983 to 2005, annual
average calving intervals ranged from 3 to 5.8 years (Knowlton et al.,
1994; Kraus et al., 2007). Between 2006 and 2015, annual average
calving intervals continued to vary within this range, but in 2016 and
2017 longer calving intervals were reported (6.3 to 6.6 years in 2016
and 10.2 years in 2017; Pettis and Hamilton, 2015, 2016; Pettis et al.,
2017a; Surrey-Marsden et al., 2017; Hayes et al., 2018b). Females have
been known to give birth as young as five years old, but the mean age
of first parturition is about 10 years old (Kraus et al., 2007).
[[Page 63319]]
Pregnant North Atlantic right whales migrate south, through the
mid-Atlantic region of the United States, to low latitudes during late
fall where they overwinter and give birth in shallow, coastal waters
(Kenney, 2009; Krzystan et al., 2018). During spring, these females
migrate back north with their new calves to high latitude foraging
grounds where they feed on large concentrations of copepods, primarily
Calanus finmarchicus (NMFS, 2017). Some non-reproductive North Atlantic
right whales (males, juveniles, non-reproducing females) also migrate
south through the mid-Atlantic region, although at more variable times
throughout the winter, while others appear to not migrate south, and
instead remain in the northern feeding grounds year round or go
elsewhere (Bort et al., 2015; Morano et al., 2012; NMFS, 2017).
Nonetheless, calving females arrive to the southern calving grounds
earlier and stay in the area more than twice as long as other
demographics (Krzystan et al., 2018). Little is known about North
Atlantic right whale habitat use in the mid-Atlantic, but recent
acoustic data indicate near year-round presence of at least some whales
off the coasts of New Jersey, Virginia, and North Carolina (Davis et
al., 2017; Hodge et al., 2015a; Salisbury et al., 2016; Whitt et al.,
2013). Oedekoven et al. (2015) conducted an expert elicitation exercise
to assess potential seasonal abundance of right whales in the mid-
Atlantic, confirming that very low numbers of whales should be expected
to be present in the region outside of the November to April timeframe.
While it is generally not known where North Atlantic right whales mate,
some evidence suggests that mating may occur in the northern feeding
grounds (Cole et al., 2013; Matthews et al., 2014).
The western North Atlantic right whale population demonstrated
overall growth of 2.8 percent per year between 1990 to 2010, despite a
decline in 1993 and no growth between 1997 and 2000 (Pace et al.,
2017). However, since 2010 the population has been in decline, with a
99.99 percent probability of a decline of just under one percent per
year (Pace et al., 2017). Between 1990 and 2015, survival rates
appeared to be relatively stable, but differed between the sexes, with
males having higher survivorship than females (males: 0.985 0.0038; females: 0.968 0.0073) leading to a male-
biased sex ratio (approximately 1.46 males per female; Pace et al.,
2017). During this same period, calving rates varied substantially,
with low calving rates coinciding with all three periods of decline or
no growth (Pace et al., 2017). On average, North Atlantic right whale
calving rates are estimated to be roughly half that of southern right
whales (E. australis) (Pace et al., 2017), which are increasing in
abundance (NMFS, 2015c).
While data are not yet available to statistically estimate the
population's trend beyond 2015, three lines of evidence indicate the
population is still in decline. First, calving rates in recent years
were low, with only five new calves being documented in 2017 (Pettis et
al., 2017a), well below the number needed to compensate for expected
mortalities (Pace et al., 2017). In 2018, no new North Atlantic right
whale calves were documented in their calving grounds; this represented
the first time since annual NOAA aerial surveys began in 1989 that no
new right whale calves were observed. Long-term photographic
identification data indicate new calves rarely go undetected, so these
years likely represent a continuation of the low calving rates that
began in 2012 (Kraus et al., 2007; Pace et al., 2017). Second, as noted
above, the abundance estimate for 2016 is 451 individuals, down
approximately 1.5 percent from 458 in 2015. Third, since June 2017, at
least 20 North Atlantic right whales have died in what has been
declared an Unusual Mortality Event (UME; see additional discussion of
the UME below).
Analysis of mtDNA from North Atlantic right whales has identified
seven mtDNA haplotypes in the western North Atlantic (Malik et al.,
1999; McLeod and White, 2010). This is significantly less diverse than
southern right whales and may indicate inbreeding (Hayes et al., 2018a;
Malik et al., 2000; Schaeff et al., 1997). While analysis of historic
DNA taken from museum specimens indicates that the eastern and western
populations were likely not genetically distinct, the lack of recovery
of the eastern North Atlantic population indicates at least some level
of population segregation (Rosenbaum et al., 1997, 2000). Overall, the
species has low genetic diversity as would be expected based on its low
abundance. However, analysis of 16th and 17th century whaling bones
indicate this low genetic diversity may pre-date whaling activities
(McLeod et al., 2010). Despite this, Frasier et al. (2013) recently
identified a post-copulatory mechanism that appears to be slowly
increasing genetic diversity among right whale calves.
In recent years, there has been a shift in distribution in right
whale feeding grounds, with fewer animals being seen in the Great South
Channel and the Bay of Fundy and perhaps more animals being observed in
the Gulf of Saint Lawrence and mid-Atlantic region (Daoust et al.,
2017; Davis et al., 2017; Hayes et al., 2018a; Pace et al., 2017;
Meyer-Gutbrod et al., 2018). However, in recent years, a few known
individuals from the western population have been seen in the eastern
Atlantic, suggesting some individuals may have wider ranges than
previously thought (Kenney, 2009).
Currently, no identified right whale recovery goals have been met
(for more information on these goals, see the 2005 recovery plan; NMFS,
2005, 2017). With whaling now prohibited, the two major known human
causes of mortality are vessel strikes and entanglement in fishing gear
(Hayes et al., 2018b). Some progress has been made in mitigating vessel
strikes by regulating vessel speeds in certain areas (78 FR 73726;
December 9, 2013) (Conn and Silber, 2013), but entanglement in fishing
gear remains a major threat (Kraus et al., 2016), which appears to be
worsening (Hayes et al., 2018b). From 1990 to 2010, the population
experienced overall growth consistent with one of its recovery goals.
However, the population is currently experiencing a UME that appears to
be related to both vessel strikes and entanglement in fishing gear
(Daoust et al., 2017; see below for further discussion). In addition,
the low female survival, male biased sex ratio, and low calving success
indicated by recent modeling are contributing to the population's
current decline (Pace et al., 2017). While there are likely a multitude
of factors involved, low calving has been linked to poor female health
(Rolland et al., 2016) and reduced prey availability (Meyer-Gutbrod and
Greene, 2014, 2017; Meyer-Gutbrod et al., 2018). Furthermore,
entanglement in fishing gear appears to have substantial health and
energetic costs that affect both survival and reproduction (Pettis et
al., 2017b; Robbins et al., 2015; Rolland et al., 2017; van der Hoop et
al., 2017; Hayes et al., 2018b; Hunt et al., 2018; Lysiak et al.,
2018). In fact, there is evidence of a population-wide decline in
health since the early 1990s, the last time the population experienced
a population decline (Rolland et al., 2016). Given this status, the
species resilience to future perturbations is considered very low
(Hayes et al., 2018b). Using a matrix population projection model,
Hayes et al. (2018b) estimate that by 2029 the population will to
decline to the 1990 estimate of 123 females if the current rate of
decline is not altered. Consistent with this, recent modelling efforts
by Meyer-Gutbrod and Greene (2017) indicate that that the species may
decline towards
[[Page 63320]]
extinction if prey conditions worsen, as predicted under future climate
scenarios, and anthropogenic mortalities are not reduced (Grieve et
al., 2017; Meyer-Gutbrod et al., 2018). In fact, recent data from the
Gulf of Maine and Gulf of St. Lawrence indicate prey densities may
already be in decline (Devine et al., 2017; Johnson et al., 2013;
Meyer-Gutbrod et al., 2018).
Discussion of Abundance Estimates--In Table 2 above, we report two
sets of abundance estimates: Those from NMFS's SARs and those predicted
by Roberts et al. (2016)--for the latter we provide both the annual
mean and maximum, for those taxa for which monthly predictions are
available (i.e., all taxa for which density surface models, versus
stratified models, were produced). Please see Table 2, footnotes 2-3
for more detail. We provided a relatively brief discussion of available
abundance estimates in the Notice of Proposed IHAs, stating that the
Roberts et al. (2016) abundance predictions are generally the most
appropriate in this case for purposes of comparison with estimated
exposures (see ``Estimated Take''). This is because the outputs of
these models were used in most cases to generate the exposure
estimates, i.e., we appropriately make relative comparisons between the
exposures predicted by the outputs of the model and the abundance
predicted by the model. Following review of public comments received
and additional review of available information regarding abundance
estimates, we provide revised and additional discussion of available
abundance estimates and our use of these herein.
Because both the SAR (in most cases) and Roberts et al. (2016)
values provide estimates of abundance only within the U.S. EEZ, whereas
the specified activities (and associated exposure estimates) extend
beyond this region out to 350 nmi, we calculated the expected abundance
of each species in the region offshore of the EEZ out to 350 nmi. These
values, reported in Table 2, are appropriately added to the Roberts et
al. (2016) EEZ estimates to provide the total model-predicted
abundance. Please see footnote 4 for more detail. Our prior use of
abundance estimates that ignore the assumed abundance of animals
outside the EEZ (explicit in the exposure estimation process) was an
error that is rectified here.
As was described in our Notice of Proposed IHAs, NMFS's SAR
abundance estimates are typically generated from the most recent
shipboard and/or aerial surveys conducted, and often incorporate
correction for detection bias. While these snapshot estimates provide
valuable information about a stock, they are not generally relevant
here for use in comparison to the take estimates, as stated above. The
Roberts et al. (2016) abundance estimates represent the output of
predictive models derived from observations and associated
environmental parameters and are in fact based on substantially more
data than are NMFS's SAR abundance estimates--thus minimizing the
influence of interannual variability on abundance estimates. For
example, NMFS's pilot whale abundance estimates from surveys conducted
in 2004 and 2011 differed by 21 percent--a change not expected to
represent the actual change in abundance--indicating that it may be
more appropriate to use a model prediction that incorporates all
available data.
The abundance values reported by Roberts et al. (2016), and which
we largely used in our analyses in the Notice of Proposed IHAs, are
mean annual abundance estimates (for species for which data are
sufficient to model seasonality; for other species only a stratified
model with static abundance could be produced). However, for those
species for which seasonal variability could be modeled (via density
surface models), abundance estimates are produced for each month
(monthly maps of species distribution and associated abundance values
are provided in supplementary reports for each taxon; these are
available online at: seamap.env.duke.edu/models/Duke-EC-GOM-2015/).
Following review of public comments received, we determined it
appropriate to use the most appropriate maximum abundance estimate for
purposes of comparison with the exposure estimate, rather than the
mean. While it is appropriate to use a mean density value in estimating
potential exposures over a year in order to avoid over- or under-
estimation, the best actual population estimate for comparison would be
the maximum theoretical population. That is, exposure estimates are
most appropriately generated through use of means precisely because
densities are expected to fluctuate within a study area throughout the
year; however, because these fluctuations do not represent actual
changes in population size, the maximum predicted abundance should be
used in comparison with a given exposure estimate.
The appropriate maximum estimate for each taxon more closely
represents actual total theoretical abundance of the stock as a whole,
as those animals may exit the study area during other months but still
exist conceptually as members of the population. The mean does not
represent the actual population abundance, because although there are
seasonal shifts in distribution, the actual population abundance should
be as estimated for the period when the largest portion of the
population is present in the area. While species may migrate or shift
distribution out of the study area, total abundance of a stock changes
only via births and deaths, i.e., there is only one true abundance of
the species. We note that for some taxa, Roberts et al. express
confidence in the monthly model outputs, e.g., where the predicted
seasonal variations in abundance match those reported in the
literature. However, for others they do not, e.g., where there is
little information available in the literature to corroborate the
predicted seasonal variation. Lack of corroboration in the latter
example would be a valid reason for not relying on monthly model
outputs when determining the timing or location of a specific project.
However, this does not impact our determination that the maximum
theoretical population abundance is appropriate to use for purposes of
comparison. For those taxa for which the monthly predictions are
recommended for use, we use the maximum monthly prediction. For the
remaining taxa for which a density surface model could be produced, we
believe that use of the maximum monthly prediction may also be
warranted. However, because for some of these species there are
substantial month-to-month fluctuations and a corresponding lack of
data in the literature regarding seasonal distribution, we use the
maximum mean seasonal (i.e., three-month) abundance prediction for
purposes of comparison as a precaution.
For most species, we use the Roberts et al. (2016) abundance
estimate, but substitute the appropriate maximum estimate for the mean
annual estimate. Where we deviate from this practice, e.g., because
another available abundance estimate provides more complete coverage of
the stock's range, we provide additional discussion below. We also note
that, regarding SAR abundance estimates, Waring et al. (2015) state
that the population of sperm whales found within the eastern U.S.
Atlantic EEZ likely represent only a fraction of the total stock,
indicating that the abundance associated with animals found in the
EEZ--whether the SAR abundance or the model-predicted abundance--likely
underestimate the true abundance of the relevant population.
Additionally, the majority of current NMFS SAR estimates--those
[[Page 63321]]
based on 2011 NOAA survey effort--do not account for availability bias
due to submerged animals, so these abundance estimates are likely
biased low.
NMFS's abundance estimate for the North Atlantic right whale is
based on models of the sighting histories of individual whales
identified using photo-identification techniques. North Atlantic right
whales represent one of the most intensely studied populations of
cetaceans in the world with effort supported by a rigorously maintained
individual sightings database and considerable survey effort throughout
their range; therefore, the most appropriate abundance estimate is
based on this photo-identification database. The current estimate of
451 individuals (95% credible intervals 434-464) reflects the database
as of November 2017 (www.fisheries.noaa.gov/national/marine-mammal-protection/draft-marine-mammal-stock-assessment-reports).
The 2007 Canadian Trans-North Atlantic Sighting Survey (TNASS),
which provided full coverage of the Atlantic Canadian coast (Lawson and
Gosselin, 2009), provided abundance estimates for multiple stocks. The
abundance estimates from this survey were corrected for perception and
availability bias, when possible. In general, where the TNASS survey
effort provided superior coverage of a stock's range (as compared with
NOAA survey effort), we elect to use the resulting abundance estimate
over either the current NMFS abundance estimate (derived from survey
effort with inferior coverage of the stock range) or the Roberts et al.
(2016) predictions (which are based on survey data from within U.S.
waters). The TNASS data were not made available to the model authors
(Roberts et al., 2015a).
We use the TNASS abundance estimate for the minke whale and for the
short-beaked common dolphin. While the TNASS survey also produced an
abundance estimate of 3,522 (CV=0.27) fin whales, and similarly better
represents the stock range than does NMFS's SAR estimate, this value
underrepresents the maximum population predicted by Roberts et al.
(2016). We also note that, while there appears to be some slight
overlap in their coverage of stock ranges, the abundance estimates
provided by the TNASS surveys and by NMFS's SAR estimates largely cover
separate portions of the ranges. The TNASS effort involved aerial
surveys covering the Labrador Shelf and Grand Banks, the Gulf of St.
Lawrence, and the Scotian Shelf, and the abundance estimates also
included the results of aerial surveys conducted by NOAA in the Bay of
Fundy. NMFS's current SAR estimates reflect NOAA shipboard and aerial
survey effort conducted from Florida to the lower Bay of Fundy.
Therefore, the most appropriate abundance estimate for these stocks may
be a combination of the abundance estimates (for common dolphin: 70,184
(SAR) + 173,486 (TNASS) = 243,670; for minke whale: 2,591 (SAR) +
20,741 (TNASS) = 23,332). Other abundance estimates that may cover
additional portions of these stocks' ranges are described in Waring et
al. (2013). However, we use only the TNASS estimates, which better
cover the stock ranges, because we are uncertain about the degree of
potential coverage overlap in Canadian waters.
Note that, while the same TNASS survey produced an abundance
estimate of 2,612 (CV=0.26) humpback whales, the survey did not provide
superior coverage of the stock's range in the same way that it did for
minke whales (Waring et al., 2016; Lawson and Gosselin, 2011). In
addition, based on photo-identification only 39 percent of individual
humpback whales observed along the mid- and south Atlantic U.S. coast
are from the Gulf of Maine stock (Barco et al., 2002). Therefore, we
use the Roberts et al. (2016) prediction for humpback whales. We note
that the Roberts et al. (2016) maximum estimate of 1,994 humpback
whales likely underrepresents the relevant population, i.e., the West
Indies breeding population. Bettridge et al. (2003) estimated the size
of this population at 12,312 (95% CI 8,688-15,954) whales in 2004-05,
which is consistent with previous population estimates of approximately
10,000-11,000 whales (Stevick et al., 2003; Smith et al., 1999) and the
increasing trend for the West Indies DPS (Bettridge et al., 2015).
However, we retain the value predicted by Roberts et al. (2016) for
appropriate comparison with the number of exposures predicted in the
U.S. EEZ.
The current SARs abundance estimate for Kogia spp. is substantially
higher than that provided by Roberts et al. (2016). However, the data
from which the SARs estimate is derived was not made available to
Roberts et al. (Roberts et al., 2015h), and those more recent surveys
reported observing substantially greater numbers of Kogia spp. than did
earlier surveys (43 sightings, more than the combined total of 31
reported from all surveys from 1992-2014 considered by Roberts et al.
(2016)) (NMFS, 2011). A 2013 NOAA survey, also not available to the
model authors, reported 68 sightings of Kogia spp. (NMFS, 2013a). In
addition, the SARs report an increase in Kogia spp. strandings (92 from
2001-05; 187 from 2007-11) (Waring et al., 2007; 2013). A simultaneous
increase in at-sea observations and strandings suggests increased
abundance of Kogia spp., though NMFS has not conducted any trend
analysis (Waring et al., 2013). Therefore, we believe the most
appropriate abundance estimate for use here is that currently reported
by NMFS in the SARs. In fact, Waring et al. (2013) suggest that because
this estimate was corrected for perception bias but not availability
bias, the true estimate could be two to four times larger.
Biologically Important Areas--Several biologically important areas
for some marine mammal species are recognized in the survey areas in
the mid- and south Atlantic. Critical habitat is designated for the
North Atlantic right whale within the southeast United States (81 FR
4838; January 27, 2016). Critical habitat is defined by section 3 of
the ESA as (1) the specific areas within the geographical area occupied
by the species, at the time it is listed, on which are found those
physical or biological features (a) essential to the conservation of
the species and (b) which may require special management considerations
or protection; and (2) specific areas outside the geographical area
occupied by the species at the time it is listed, upon a determination
by the Secretary that such areas are essential for the conservation of
the species. Critical habitat for the right whale in the southeast
United States (i.e., Unit 2) encompasses calving habitat and is
designated on the basis of the following essential features: (1) Calm
sea surface conditions of Force 4 or less on the Beaufort Wind Scale;
(2) sea surface temperatures from a minimum of 7[deg] C, and never more
than 17[deg] C; and (3) water depths of 6 to 28 m, where these features
simultaneously co-occur over contiguous areas of at least 231 nmi\2\ of
ocean waters during the months of November through April. When these
features are available, they are selected by right whale cows and
calves in dynamic combinations that are suitable for calving, nursing,
and rearing, and which vary, within the ranges specified, depending on
factors such as weather and age of the calves.
The area associated with such features includes nearshore and
offshore waters of the southeastern United States, extending from Cape
Fear, North Carolina south to 28[deg] N. The specific area designated
as Unit 2 of critical habitat, as defined by regulation (81 FR 4838;
January 27, 2016), is demarcated by rhumb lines connecting the specific
points identified in 50 CFR 226.203(b)(2), as shown in Figure 2.
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There is no critical habitat designated for any other species within
the survey area.
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Biologically important areas for North Atlantic right whales in the
mid- and south Atlantic were further described by LaBrecque et al.
(2015). The authors describe an area of importance for reproduction
that somewhat expands the boundaries of the critical habitat
designation, including waters out to the 25-m isobath from Cape
Canaveral to Cape Lookout from mid-November to mid-April, on the basis
of habitat analyses (Good, 2008; Keller et al., 2012) and sightings
data (e.g., Keller et al., 2006; Schulte and Taylor, 2012) indicating
that sea surface temperatures between 13[deg] to 15[deg] C and water
depths between 10-20 m are critical parameters for calving. Right
whales leave northern feeding grounds in November and December to
migrate along the continental shelf to the calving grounds or to
unknown winter areas before returning to northern areas by late spring.
Right whales are known to travel along the continental shelf, but it is
unknown whether they use the entire shelf area or are restricted to
nearshore waters (Schick et al., 2009; Whitt et al., 2013). LaBrecque
et al. (2015) define an important area for migratory behavior on the
basis of aerial and vessel-based survey data, photo-identification
data, radio-tracking data, and expert judgment.
As noted by LaBrecque et al. (2015), additional cetacean species
are known to have strong links to bathymetric features, although there
is currently insufficient information to specifically identify these
areas. For example, pilot whales and Risso's dolphins aggregate at the
shelf break in the survey area. These and other locations predicted as
areas of high abundance (Roberts et al., 2016) form the basis of
spatiotemporal restrictions on survey effort as described under
``Mitigation.'' In addition, other data indicate potential areas of
importance that are not yet fully described. Risch et al. (2014)
describe minke whale presence offshore of the shelf break (evidenced by
passive acoustic recorders), which may be indicative of a migratory
area, while other data provides evidence that sei whales aggregate near
meandering frontal eddies over the continental shelf in the Mid-
Atlantic Bight (Newhall et al., 2012).
Unusual Mortality Events (UME)--A UME is defined under the MMPA as
``a stranding that is unexpected; involves a significant die-off of any
marine mammal population; and demands immediate response.'' From 1991
to the present, there have been approximately twelve formally
recognized UMEs affecting marine mammals in the survey area and
involving species under NMFS's jurisdiction. A recently ended UME
involved bottlenose dolphins. Three UMEs are ongoing and under
investigation. These involve humpback whales, North Atlantic right
whales, and minke whales. Specific information for each ongoing UME is
provided below. There is currently no direct connection between the
three UMEs, as there is no evident cause of stranding or death that is
common across the three species involved in the different UMEs.
Additionally, strandings across the three species are not clustering in
space or time.
Since January 2016, elevated humpback whale mortalities have
occurred along the Atlantic coast from Maine through Florida (though
there are only two records to date south of North Carolina). As of
October 2018, partial or full necropsy examinations have been conducted
on approximately half of the 84 known cases. Of the cases examined,
approximately half had evidence of human interaction (ship strike or
entanglement). Some of these investigated mortalities showed blunt
force trauma or pre-mortem propeller wounds indicative of vessel
strike, indicating a strike rate above the annual long-term average;
however, these findings of pre-mortem vessel strike are not consistent
across all of the whales examined and more research is needed. NOAA is
consulting with researchers that are conducting studies on the humpback
whale populations, and these efforts may provide information on changes
in whale distribution and habitat use that could provide additional
insight into how these vessel interactions occurred. Three previous
UMEs involving humpback whales have occurred since 2000, in 2003, 2005,
and 2006. More information is available at www.fisheries.noaa.gov/national/marine-life-distress/2016-2018-humpback-whale-unusual-mortality-event-along-atlantic-coast (accessed October 17, 2018).
Since January 2017, elevated minke whale strandings have occurred
along the Atlantic coast from Maine through South Carolina, with
highest numbers in Massachusetts, Maine, and New York. As of October
2018, partial or full necropsy examinations have been conducted on more
than 60 percent of the 54 known cases. Preliminary findings in several
of the whales have shown evidence of human interactions or infectious
disease. These findings are not consistent across all of the whales
examined, so more research is needed. As part of the UME investigation
process, NOAA is assembling an independent team of scientists to
coordinate with the Working Group on Marine Mammal Unusual Mortality
Events to review the data collected, sample stranded whales, and
determine the next steps for the investigation. More information is
available at: www.fisheries.noaa.gov/national/marine-life-distress/2017-2018-minke-whale-unusual-mortality-event-along-atlantic-coast
(accessed October 17, 2018).
Elevated North Atlantic right whale mortalities began in June 2017,
primarily in Canada. To date, there are a total of 20 confirmed dead
stranded whales (12 in Canada; 8 in the United States), and 5 live
whale entanglements in Canada have been documented. Full necropsy
examinations have been conducted on 13 of the cases, with results
currently available for seven of these that occurred in Canada (Daoust
et al., 2017). Results indicate that two whales died from entanglement
in fishing gear and, for four whales, necropsy findings were compatible
with acute death due to trauma (although it is uncertain whether they
were struck pre- or post-mortem) (Daoust et al., 2017). Several
investigated cases are undetermined due to advanced decomposition.
Overall, findings to date confirm that vessel strikes and fishing gear
entanglement continue to be the key threats to recovery of North
Atlantic right whales. In response, the Canadian government has enacted
fishery closures to help reduce future entanglements and has modified
fixed gear fisheries, as well as implementing temporary mandatory
vessel speed restrictions in a portion of the Gulf of St. Lawrence.
NOAA is cooperating with Canadian government officials as they
investigate the incidents in Canadian waters. A previous UME involving
right whales occurred in 1996. More information is available at:
www.fisheries.noaa.gov/national/marine-life-distress/2017-2018-north-atlantic-right-whale-unusual-mortality-event (accessed October 17,
2018).
Beginning in July 2013, elevated strandings of bottlenose dolphins
were observed along the Atlantic coast from New York to Florida. The
investigation was closed in 2015, with the UME ultimately being
attributed to cetacean morbillivirus (though additional contributory
factors are under investigation; www.fisheries.noaa.gov/national/marine-life-distress/2013-2015-bottlenose-dolphin-unusual-mortality-event-mid-atlantic; accessed July 2, 2018). Dolphin strandings during
2013-15 were greater than six times higher than the annual average from
2007-12, with the most strandings reported from Virginia, North
Carolina, and Florida. A
[[Page 63324]]
total of approximately 1,650 bottlenose dolphins stranded from June
2013 to March 2015 and, additionally, a small number of individuals of
several other cetacean species stranded during the UME and tested
positive for morbillivirus (humpback whale, fin whale, minke whale,
pygmy sperm whale, and striped dolphin). Only one offshore ecotype
dolphin has been identified, meaning that over 99 percent of affected
dolphins were of the coastal ecotype (D. Fauquier; pers. comm.).
Research, to include analyses of stranding samples and post-UME
monitoring and modeling of surviving populations, will continue in
order to better understand the impacts of the UME on the affected
stocks. Notably, an earlier major UME in 1987-88 was also caused by
morbillivirus. Over 740 stranded dolphins were recovered during that
event.
Additional recent UMEs include various localized events with
undetermined cause involving bottlenose dolphins (e.g., South Carolina
in 2011; Virginia in 2009) and an event affecting common dolphins and
Atlantic white-sided dolphins from North Carolina to New Jersey (2008;
undetermined). For more information on UMEs, please visit:
www.fisheries.noaa.gov/national/marine-life-distress/marine-mammal-unusual-mortality-events.
Take Reduction Planning--Take reduction plans are designed to help
recover and prevent the depletion of strategic marine mammal stocks
that interact with certain U.S. commercial fisheries, as required by
Section 118 of the MMPA. The immediate goal of a take reduction plan is
to reduce, within six months of its implementation, the mortality and
serious injury of marine mammals incidental to commercial fishing to
less than the potential biological removal level. The long-term goal is
to reduce, within five years of its implementation, the mortality and
serious injury of marine mammals incidental to commercial fishing to
insignificant levels, approaching a zero serious injury and mortality
rate, taking into account the economics of the fishery, the
availability of existing technology, and existing state or regional
fishery management plans. Take reduction teams are convened to develop
these plans.
There are several take reduction plans in place for marine mammals
in the survey areas of the mid- and south Atlantic. We described these
here briefly in order to fully describe, in conjunction with referenced
material, the baseline conditions for the affected marine mammal
stocks. The Atlantic Large Whale Take Reduction Plan (ALWTRP) was
implemented in 1997 to reduce injuries and deaths of large whales due
to incidental entanglement in fishing gear. The ALWTRP is an evolving
plan that changes as NMFS learns more about why whales become entangled
and how fishing practices might be modified to reduce the risk of
entanglement. It has several components, including restrictions on
where and how gear can be set and requirements for entangling gears
(i.e., trap/pot and gillnet gears). The ALWTRP addresses those species
most affected by fishing gear entanglements, i.e., North Atlantic right
whale, humpback whale, fin whale, and minke whale. Annual human-caused
mortality exceeds PBR for the North Atlantic right whale and certain
other ESA-listed whale species. More information is available online
at: www.greateratlantic.fisheries.noaa.gov/protected/whaletrp/.
NMFS implemented a Harbor Porpoise Take Reduction Plan (HPTRP) to
reduce interactions between harbor porpoise and commercial gillnet gear
in both New England and the mid-Atlantic. The HPTRP has several
components including restrictions on where, when, and how gear can be
set, and in some areas requires the use of acoustic deterrent devices.
More information is available online at:
www.greateratlantic.fisheries.noaa.gov/protected/porptrp/.
The Atlantic Trawl Gear Take Reduction Team was developed to
address the incidental mortality and serious injury of pilot whales,
common dolphins, and white-sided dolphins incidental to Atlantic trawl
fisheries. More information is available online at:
www.greateratlantic.fisheries.noaa.gov/Protected/mmp/atgtrp/.
Separately, NMFS established a Pelagic Longline Take Reduction Plan
(PLTRP) to address the incidental mortality and serious injury of pilot
whales in the mid-Atlantic region of the Atlantic pelagic longline
fishery. The PLTRP includes a special research area, gear
modifications, outreach material, observer coverage, and captains'
communications. Pilot whales incur substantial incidental mortality and
serious injury due to commercial fishing, and therefore are of
particular concern. More information is available online at:
www.nmfs.noaa.gov/pr/interactions/trt/pl-trt.html.
Marine Mammal Hearing
Hearing is the most important sensory modality for marine mammals
underwater, and exposure to anthropogenic sound can have deleterious
effects. To appropriately assess the potential effects of exposure to
sound, it is necessary to understand the frequency ranges marine
mammals are able to hear. Current data indicate that not all marine
mammal species have equal hearing capabilities (e.g., Richardson et
al., 1995; Wartzok and Ketten, 1999; Au and Hastings, 2008). To reflect
this, Southall et al. (2007) recommended that marine mammals be divided
into functional hearing groups based on directly measured or estimated
hearing ranges on the basis of available behavioral response data,
audiograms derived using auditory evoked potential techniques,
anatomical modeling, and other data. Note that no direct measurements
of hearing ability have been successfully completed for mysticetes
(i.e., low-frequency cetaceans). NMFS (2018) describes generalized
hearing ranges for these marine mammal hearing groups. Generalized
hearing ranges were chosen based on the approximately 65 dB threshold
from the normalized composite audiograms, with the exception for lower
limits for low-frequency cetaceans where the lower bound was deemed to
be biologically implausible and the lower bound from Southall et al.
(2007) retained. Pinniped functional hearing is not discussed here, as
no pinnipeds are expected to be affected by the specified activity. The
functional groups and the associated frequencies are indicated below
(note that these frequency ranges correspond to the range for the
composite group, with the entire range not necessarily reflecting the
capabilities of every species within that group):
Low-frequency cetaceans (mysticetes): Generalized hearing
is estimated to occur between approximately 7 Hz and 35 kHz;
Mid-frequency cetaceans (larger toothed whales, beaked
whales, and most delphinids): Generalized hearing is estimated to occur
between approximately 150 Hz and 160 kHz;
High-frequency cetaceans (porpoises, river dolphins, and
members of the genera Kogia and Cephalorhynchus; including two members
of the genus Lagenorhynchus, on the basis of recent echolocation data
and genetic data): Generalized hearing is estimated to occur between
approximately 275 Hz and 160 kHz.
For more detail concerning these groups and associated frequency
ranges, please see NMFS (2018) for a review of available information.
Thirty-four marine mammal species, all cetaceans, have the reasonable
potential to co-occur with the survey activities. Please refer to Table
2. Of the species that may
[[Page 63325]]
be present, seven are classified as low-frequency cetaceans (i.e., all
mysticete species), 24 are classified as mid-frequency cetaceans (i.e.,
all delphinid and ziphiid species and the sperm whale), and three are
classified as high-frequency cetaceans (i.e., harbor porpoise and Kogia
spp.).
Potential Effects of the Specified Activities on Marine Mammals and
Their Habitat
In our Notice of Proposed IHAs, this section included a
comprehensive summary and discussion of the ways that components of the
specified activity may impact marine mammals and their habitat,
including general background information on sound and specific
discussion of potential effects to marine mammals from noise produced
through use of airgun arrays. We do not repeat that discussion here,
instead referring the reader to the Notice of Proposed IHAs. However,
we do provide a more thorough discussion regarding potential impacts to
marine mammal habitat via effects to prey species, as well as
discussion of important new information regarding potential impacts to
prey species produced since publication of our notice. The ``Estimated
Take'' section later in this document includes a quantitative analysis
of the number of individuals that are expected to be taken by this
activity. The ``Negligible Impact Analyses and Determinations'' section
will include an analysis of how these specific activities will impact
marine mammals and will consider the content of this section, the
``Estimated Take'' section, and the ``Mitigation'' section, to draw
conclusions regarding the likely impacts of these activities on the
reproductive success or survivorship of individuals and from that on
the affected marine mammal populations.
Description of Active Acoustic Sound Sources
In our Notice of Proposed IHAs, this section contained a brief
technical background on sound, the characteristics of certain sound
types, and on metrics used in the proposal inasmuch as the information
is relevant to the specified activity and to a discussion of the
potential effects of the specified activity on marine mammals found
later in this document. Here, we summarize key information relating to
terminology used in this notice.
Amplitude (or ``loudness'') of sound is typically described using
the relative unit of the decibel (dB). A sound pressure level (SPL) in
dB is described as the ratio between a measured pressure and a
reference pressure (for underwater sound, this is 1 microPascal
([mu]Pa)). The source level (SL) represents the SPL referenced at a
distance of 1 m from the source (referenced to 1 [mu]Pa), while the
received level is the SPL at the listener's position (referenced to 1
[mu]Pa).
Root mean square (rms) is the quadratic mean sound pressure over
the duration of an impulse. This measurement is often used in the
context of discussing behavioral effects, in part because behavioral
effects, which often result from auditory cues, may be better expressed
through averaged units than by peak pressures. Sound exposure level
(SEL; represented as dB re 1 [mu]Pa\2\-s) represents the total energy
contained within a pulse, and considers both intensity and duration of
exposure. Peak sound pressure (also referred to as zero-to-peak sound
pressure or 0-p) is the maximum instantaneous sound pressure measurable
in the water at a specified distance from the source, and is
represented in the same units as the rms sound pressure. Another common
metric is peak-to-peak sound pressure (pk-pk), which is the algebraic
difference between the peak positive and peak negative sound pressures.
Peak-to-peak pressure is typically approximately 6 dB higher than peak
pressure (Southall et al., 2007).
As described in more detail in our Notice of Proposed IHAs, airgun
arrays are in a general sense considered to be omnidirectional sources
of pulsed noise. Pulsed sound sources (as compared with non-pulsed
sources) produce signals that are brief (typically considered to be
less than one second), broadband, atonal transients (ANSI, 1986, 2005;
Harris, 1998; NIOSH, 1998; ISO, 2003) and occur either as isolated
events or repeated in some succession. Pulsed sounds are all
characterized by a relatively rapid rise from ambient pressure to a
maximal pressure value followed by a rapid decay period that may
include a period of diminishing, oscillating maximal and minimal
pressures, and generally have an increased capacity to induce physical
injury as compared with sounds that lack these features. Airguns
produce sound with energy in a frequency range from about 10-2,000 Hz,
with most energy radiated at frequencies below 200 Hz. Although the
amplitude of the acoustic wave emitted from the source is equal in all
directions (i.e., omnidirectional), airgun arrays do possess some
directionality due to different phase delays between guns in different
directions. Airgun arrays are typically tuned to maximize functionality
for data acquisition purposes, meaning that sound transmitted in
horizontal directions and at higher frequencies is minimized to the
extent possible.
Anticipated Effects on Marine Mammal Habitat
We received numerous public comments regarding potential effects to
marine mammal habitat, including to prey species, including some
comments pointing out additional relevant literature and/or claiming
that we had not adequately considered potential impacts to prey
species. While we disagree that we had not adequately considered
potential impacts to marine mammal habitat, particularly with regard to
marine mammal prey, in response to public comment we did consider
additional literature regarding potential impacts to prey species, as
well as some new literature made available since publication of our
Notice of Proposed IHAs (e.g., McCauley et al., 2017). Portions of this
information were described in responses to comments above. We provide a
revised summary of our review of available literature regarding impacts
to prey species here (please see our Notice of Proposed IHAs for our
discussions of potential effects to other aspects of marine mammal
habitat, including acoustic habitat). Our overall conclusions regarding
potential impacts of the specified activities on marine mammal habitat
are unchanged. As stated in our Notice of Proposed IHAs, our review of
the available information and the specific nature of the activities
considered herein suggest that the activities associated with the
planned actions are not likely to have more than short-term adverse
effects on any prey habitat or populations of prey species or on the
quality of acoustic habitat. Further, any impacts to marine mammal
habitat are not expected to result in significant or long-term
consequences for individual marine mammals, or to contribute to adverse
impacts on their populations. Information supporting this conclusion is
summarized below.
Effects to Prey--As stated above, here we provide an updated and
more detailed discussion of the available information regarding
potential effects to prey, as well as additional support for our
conclusion.
Sound may affect marine mammals through impacts on the abundance,
behavior, or distribution of prey species (e.g., crustaceans,
cephalopods, fish, zooplankton). Marine mammal prey varies by species,
season, and location and, for some, is not well documented. Here, we
describe studies regarding the effects of noise on known marine mammal
prey.
[[Page 63326]]
Fish utilize the soundscape (see our Notice of Proposed IHAs for
discussion of this concept) and components of sound in their
environment to perform important functions such as foraging, predator
avoidance, mating, and spawning (e.g., Zelick et al., 1999; Fay, 2009).
Depending on their hearing anatomy and peripheral sensory structures,
which vary among species, fishes hear sounds using pressure and
particle motion sensitivity capabilities and detect the motion of
surrounding water (Fay et al., 2008). The potential effects of airgun
noise on fishes depends on the overlapping frequency range, distance
from the sound source, water depth of exposure, and species-specific
hearing sensitivity, anatomy, and physiology. Key impacts to fishes may
include behavioral responses, hearing damage, barotrauma (pressure-
related injuries), and mortality.
Fish react to sounds which are especially strong and/or
intermittent low-frequency sounds, and behavioral responses such as
flight or avoidance are the most likely effects. Short duration, sharp
sounds can cause overt or subtle changes in fish behavior and local
distribution. The reaction of fish to airguns depends on the
physiological state of the fish, past exposures, motivation (e.g.,
feeding, spawning, migration), and other environmental factors.
Hastings and Popper (2005) identified several studies that suggest fish
may relocate to avoid certain areas of sound energy. Several studies
have demonstrated that airgun sounds might affect the distribution and
behavior of some fishes, potentially impacting foraging opportunities
or increasing energetic costs (e.g., Fewtrell and McCauley, 2012;
Pearson et al., 1992; Skalski et al., 1992; Santulli et al., 1999). One
recent study found a 78 percent decline in snapper-grouper complex
species abundance during evening hours at a reef habitat site off
central North Carolina following an airgun survey (Paxton et al.,
2017). During the days prior to the survey passing, fish use of this
habitat was highest during the same hours.
However, our review shows that the bulk of studies indicate no or
slight reaction to noise (e.g., Miller and Cripps, 2013; Dalen and
Knutsen, 1987; Pena et al., 2013; Chapman and Hawkins, 1969; Wardle et
al., 2001; Sara et al., 2007; Jorgenson and Gyselman, 2009; Blaxter et
al., 1981; Cott et al., 2012; Boeger et al., 2006), and that, most
commonly, while there are likely to be impacts to fish as a result of
noise from nearby airguns, such effects will be temporary. For example,
investigators reported significant, short-term declines in commercial
fishing catch rate of gadid fishes during and for up to five days after
seismic survey operations, but the catch rate subsequently returned to
normal (Engas et al., 1996; Engas and Lokkeborg, 2002); other studies
have reported similar findings (Hassel et al., 2004). Skalski et al.
(1992) also found a reduction in catch rates--for rockfish (Sebastes
spp.) in response to controlled airgun exposure--but suggested that the
mechanism underlying the decline was not dispersal but rather decreased
responsiveness to baited hooks associated with an alarm behavioral
response. A companion study showed that alarm and startle responses
were not sustained following the removal of the sound source (Pearson
et al., 1992); therefore, Skalski et al. (1992) suggested that the
effects on fish abundance may be transitory, primarily occurring during
the sound exposure itself. In some cases, effects on catch rates are
variable within a study, which may be more broadly representative of
temporary displacement of fish in response to airgun noise (i.e., catch
rates may increase in some locations and decrease in others) than any
long-term damage to the fish themselves (Streever et al., 2016).
While the findings of Paxton et al. (2017) may be interpreted as a
significant shift in distribution that could compromise life history
behaviors--as some commenters have done--we interpret these findings as
corroborating prior studies indicating that typically a startle
response or short-term displacement should be expected. In fact, the
evening hours during which the decline in fish habitat use were
recorded (via video recording) occurred on the same day that the airgun
survey passed, and no subsequent data is presented to support an
inference that the response was long-lasting. Additionally, given that
the finding is based on video images, the lack of recorded fish
presence does not support a conclusion that the fish actually moved
away from the site or suffered any serious impairment. Other studies
have been inconclusive regarding the abundance effects of airgun noise
(Thomson et al., 2014).
SPLs of sufficient strength have been known to cause injury to fish
and fish mortality and, in some studies, fish auditory systems have
been damaged by airgun noise (McCauley et al., 2003; Popper et al.,
2005; Song et al., 2008). (No mortality occurred to fish in any of
these studies.) While experiencing a TTS, fish may be more susceptible
to fitness impacts resulting from effects to communication, predator/
prey detection, etc. (Popper et al., 2014). However, in most fish
species, hair cells in the ear continuously regenerate and loss of
auditory function likely is restored when damaged cells are replaced
with new cells (Smith, 2016). Halvorsen et al. (2012a) showed that a
TTS of 4-6 dB was recoverable within 24 hours for one species. Impacts
would be most severe when the individual fish is close to the source
and when the duration of exposure is long--neither condition should be
expected in relation to the specified activities.
Injury caused by barotrauma can range from slight to severe and can
cause death, and is most likely for fish with swim bladders. Barotrauma
injuries have been documented during controlled exposure to impact pile
driving (an impulsive noise source, as are airguns) (Halvorsen et al.,
2012b; Casper et al., 2013). For geophysical surveys, the sound source
is constantly moving, and most fish would likely avoid the sound source
prior to receiving sound of sufficient intensity to cause physiological
or anatomical damage.
Invertebrates appear to be able to detect sounds (Pumphrey, 1950;
Frings and Frings, 1967) and are most sensitive to low-frequency sounds
(Packard et al., 1990; Budelmann and Williamson, 1994; Lovell et al.,
2005; Mooney et al., 2010). Available data suggest that cephalopods are
capable of sensing the particle motion of sounds and detect low
frequencies up to 1-1.5 kHz, depending on the species, and so are
likely to detect airgun noise (Kaifu et al., 2008; Hu et al., 2009;
Mooney et al., 2010; Samson et al., 2014). Cephalopods have a
specialized sensory organ inside the head called a statocyst that may
help an animal determine its position in space (orientation) and
maintain balance (Budelmann, 1992). Packard et al. (1990) showed that
cephalopods were sensitive to particle motion, not sound pressure, and
Mooney et al. (2010) demonstrated that squid statocysts act as an
accelerometer through which particle motion of the sound field can be
detected. Auditory injuries (lesions occurring on the statocyst sensory
hair cells) have been reported upon controlled exposure to low-
frequency sounds, suggesting that cephalopods are particularly
sensitive to low-frequency sound (Andre et al., 2011; Sole et al.,
2013); however, these controlled exposures involved long exposure to
sounds dissimilar to airgun pulses (i.e., 2 hours of continuous
exposure to 1-second sweeps, 50-400 Hz). Behavioral responses, such as
inking and jetting, have also been reported upon exposure to low-
[[Page 63327]]
frequency sound (McCauley et al., 2000b; Samson et al., 2014).
Impacts to benthic communities from impulsive sound generated by
active acoustic sound sources are not well documented. There are no
published data that indicate whether threshold shift injuries or
effects of auditory masking occur in benthic invertebrates, and there
are little data to suggest whether sounds from seismic surveys would
have any substantial impact on invertebrate behavior (Hawkins et al.,
2014), though some studies have indicated no short-term or long-term
effects of airgun exposure (e.g., Andriguetto-Filho et al., 2005; Payne
et al., 2007; 2008; Boudreau et al., 2009). Exposure to airgun signals
was found to significantly increase mortality in scallops, in addition
to causing significant changes in behavioral patterns and disruption of
hemolymph chemistry during exposure (Day et al., 2017). However, the
implications of this finding are not straightforward, as the authors
state that the observed levels of mortality were not beyond naturally
occurring rates. Fitzgibbon et al. (2017) found significant changes to
hemolymph cell counts in spiny lobsters subjected to repeated airgun
signals, with the effects lasting up to a year post-exposure. However,
despite the high levels of exposure, direct mortality was not observed.
Further, in reference to the study, Day et al. (2016) stated that
``[s]eismic surveys appear to be unlikely to result in immediate large
scale mortality [ . . . ] and, on their own, do not appear to result in
any degree of mortality'' and that ``[e]arly stage lobster embryos
showed no effect from air gun exposure, indicating that at this point
in life history, they are resilient to exposure and subsequent
recruitment should be unaffected.''
There is little information concerning potential impacts of noise
on zooplankton populations. However, one recent study (McCauley et al.,
2017) investigated zooplankton abundance, diversity, and mortality
before and after exposure to airgun noise, finding that the exposure
resulted in significant depletion for more than half the taxa present
and that there were two to three times more dead zooplankton after
airgun exposure compared with controls for all taxa. The majority of
taxa present were copepods and cladocerans; for these taxa, the range
within which effects on abundance were detected was up to approximately
1.2 km. In order to have significant impacts on r-selected species such
as plankton, the spatial or temporal scale of impact must be large in
comparison with the ecosystem concerned (McCauley et al., 2017). It is
also possible that the findings reflect avoidance by zooplankton rather
than mortality (McCauley et al., 2017). Therefore, the large scale of
effect observed here is of concern--particularly where repeated noise
exposure is expected--and further study is warranted.
A modeling exercise was conducted as a follow-up to the McCauley et
al. (2017) study, in order to assess the potential for impacts on ocean
ecosystem dynamics and zooplankton population dynamics (Richardson et
al., 2017). Richardson et al. (2017) found that for copepods with a
short life cycle in a high-energy environment, a full-scale airgun
survey would impact copepod abundance up to three days following the
end of the survey, suggesting that effects such as those found by
McCauley et al. (2017) would not be expected to be detectable
downstream of the survey areas, either spatially or temporally.
However, these findings are relevant for zooplankton with rapid
reproductive cycles in areas where there is a high natural
replenishment rate resulting from new water masses moving in, and the
findings may not apply in lower-energy environments or for zooplankton
with longer life-cycles. In fact, the study found that by turning off
the current, as may reflect lower-energy environments, the time to
recovery for the modelled population extended from several days to
several weeks.
In the absence of further validation of the McCauley et al. (2017)
findings, if we assume a worst-case likelihood of severe impacts to
zooplankton within approximately 1 km of the acoustic source, the large
spatial scale and expected wide dispersal of survey vessels does not
lead us to expect any meaningful follow-on effects to the prey base for
odontocete predators (the region is not an important feeding area for
taxa that feed directly on zooplankton, i.e., mysticetes). While the
large scale of effect observed by McCauley et al. (2017) may be of
concern, NMFS concludes that these findings indicate a need for more
study, particularly where repeated noise exposure is expected--a
condition unlikely to occur in relation to the time period in which the
surveys considered for the five IHAs will take place.
A recent review article concluded that, while laboratory results
provide scientific evidence for high-intensity and low-frequency sound-
induced physical trauma and other negative effects on some fish and
invertebrates, the sound exposure scenarios in some cases are not
realistic to those encountered by marine organisms during routine
seismic operations (Carroll et al., 2017). The review finds that there
has been no evidence of reduced catch or abundance following seismic
activities for invertebrates, and that there is conflicting evidence
for fish with catch observed to increase, decrease, or remain the same.
Further, where there is evidence for decreased catch rates in response
to airgun noise, these findings provide no information about the
underlying biological cause of catch rate reduction (Carroll et al.,
2017).
As addressed earlier in ``Comments and Responses,'' some members of
the public made strong assertions regarding the likely effects of
airgun survey noise on marine mammal prey. These assertions included,
for example, that the specified activities would harm fish and
invertebrate species over the long-term, cause reductions in
recruitment and effects to behavior that may reduce reproductive
potential and foraging success and increase the risk of predation, and
induce changes in community composition via such population-level
impacts. We have addressed these claims both in our comment responses
and in our review of the available literature, above. We also reviewed
available information regarding populations of representative prey
stocks in the northern Gulf of Mexico (GOM), which is the only U.S.
location where marine seismic surveys are a routinely occurring
activity. While we recognize the need for caution in assuming
correlation between the ongoing survey activity in the GOM and the
health of assessed stocks there, we believe this information has some
value in informing the likelihood of population-level effects to prey
species and, therefore, the likelihood that the specified activities
would negatively impact marine mammal populations via effects to prey.
We note that the information reported below is in context of managed
commercial and recreational fishery exploitation, in addition to any
other impacts (e.g., noise) on the stocks. The species listed below are
known prey species for marine mammals and represent groups with
different life histories and patterns of habitat use.
Red snapper (Lutjanus campechanus): Red snapper are
bottom-dwelling fish generally found at approximately 10-190 m deep
that typically live near hard structures on the continental shelf that
have moderate to high relief (for example, coral reefs, artificial
reefs, rocks, ledges, and caves), sloping soft-bottom areas, and
limestone deposits. Larval snapper swim freely within the water column.
Increases in total and spawning stock biomass are
[[Page 63328]]
predicted beginning in about 1990 (Cass-Calay et al., 2015). Regional
estimates suggest that recruitment in the west has generally increased
since the 1980s, and has recently been above average, while recruitment
in the east peaked in the mid-2000s, and has since declined. However,
the most recent assessment suggests a less significant decline (to
moderate levels) (Cass-Calay et al., 2015).
Yellowfin tuna (Thunnus albacares): Yellowfin tuna are
highly migratory, living in deep pelagic waters, and spawn in the GOM
from May to August. However, we note that a single stock is currently
assumed for the entire Atlantic, with additional spawning grounds in
the Gulf of Guinea, Caribbean Sea, and off Cabo Verde. The most recent
assessment indicates that spawning stock biomass for yellowfin tuna is
stable or increasing somewhat and that, overall, the stock is near
levels that produce the maximum sustainable yield (ICCAT, 2016).
King mackerel (Scomberomorus cavalla): King mackerel are a
coastal pelagic species, found in open waters near the coast in waters
from approximately 35-180 m deep. King mackerel migrate in response to
changes in water temperature, and spawn in shelf waters from May
through October. Estimates of recruitment demonstrate normal cyclical
patterns over the past 50 years, with a period of higher recruitment
most recently (1990-2007) (SEDAR, 2014). Long-term spawning stock
biomass patterns indicate that the spawning stock has been either
rebuilding or remained relatively consistent over the last 20 years,
with nothing indicating that the stock has declined in these recent
decades (SEDAR, 2014).
In summary, impacts of the specified activities will likely be
limited to behavioral responses, the majority of prey species will be
capable of moving out of the project area during surveys, a rapid
return to normal recruitment, distribution, and behavior for prey
species is anticipated, and, overall, impacts to prey species will be
minor and temporary. Prey species exposed to sound might move away from
the sound source, experience TTS, experience masking of biologically
relevant sounds, or show no obvious direct effects. Mortality from
decompression injuries is possible in close proximity to a sound, but
only limited data on mortality in response to airgun noise exposure are
available (Hawkins et al., 2014). The most likely impacts for most prey
species in a given survey area would be temporary avoidance of the
area. Surveys using towed airgun arrays move through an area relatively
quickly, limiting exposure to multiple impulsive sounds. In all cases,
sound levels would return to ambient once a survey moves out of the
area or ends and the noise source is shut down and, when exposure to
sound ends, behavioral and/or physiological responses are expected to
end relatively quickly (McCauley et al., 2000b). The duration of fish
avoidance of a given area after survey effort stops is unknown, but a
rapid return to normal recruitment, distribution, and behavior is
anticipated. While the potential for disruption of spawning
aggregations or schools of important prey species can be meaningful on
a local scale, the mobile and temporary nature of most surveys and the
likelihood of temporary avoidance behavior suggest that impacts would
be minor.
Based on the information discussed herein, we reaffirm our
conclusion that impacts of the specified activities are not likely to
have more than short-term adverse effects on any prey habitat or
populations of prey species. Further, any impacts to marine mammal
habitat are not expected to result in significant or long-term
consequences for individual marine mammals, or to contribute to adverse
impacts on their populations.
Estimated Take
This section provides information regarding the number of
incidental takes authorized, which informs both NMFS's consideration of
``small numbers'' and the negligible impact determinations.
Except with respect to certain activities not pertinent here,
section 3(18) of the MMPA defines ``harassment'' as: Any act of
pursuit, torment, or annoyance which (i) has the potential to injure a
marine mammal or marine mammal stock in the wild (Level A harassment);
or (ii) has the potential to disturb a marine mammal or marine mammal
stock in the wild by causing disruption of behavioral patterns,
including, but not limited to, migration, breathing, nursing, breeding,
feeding, or sheltering (Level B harassment).
Anticipated takes would primarily be by Level B harassment, as use
of the acoustic sources (i.e., airgun arrays) can result in disruption
of behavioral patterns for individual marine mammals. There is also
some potential for auditory injury (Level A harassment) to result for
low- and high-frequency species due to the size of the predicted
auditory injury zones for those species. We do not expect auditory
injury to occur for mid-frequency species, as discussed in greater
detail below. The required mitigation and monitoring measures are
expected to minimize the severity of such taking to the extent
practicable. It is unlikely that lethal takes would occur even in the
absence of the mitigation and monitoring measures, and no such takes
are anticipated or authorized. Below we describe how the authorized
take was estimated using acoustic thresholds, sound field modeling, and
marine mammal density data.
Acoustic Thresholds
NMFS uses acoustic thresholds that identify the received level of
underwater sound above which exposed marine mammals generally would be
reasonably expected to exhibit disruption of behavioral patterns
(equated to Level B harassment) or to incur PTS of some degree (equated
to Level A harassment).
Level B Harassment--Although available data are consistent with the
basic concept that louder sounds evoke more significant behavioral
responses than softer sounds, defining precise sound levels that will
potentially disrupt behavioral patterns is difficult because responses
depend on the context in which the animal receives the sound, including
an animal's behavioral mode when it hears sounds (e.g., feeding,
resting, or migrating), prior experience, and biological factors (e.g.,
age and sex). Some species, such as beaked whales, are known to be more
highly sensitive to certain anthropogenic sounds than other species.
Other contextual factors, such as signal characteristics, distance from
the source, duration of exposure, and signal to noise ratio, may also
help determine response to a given received level of sound. Therefore,
levels at which responses occur are not necessarily consistent and can
be difficult to predict (Southall et al., 2007; Ellison et al., 2012;
Bain and Williams, 2006).
However, based on the practical need to use a relatively simple
threshold based on available information that is both predictable and
measurable for most activities, NMFS has historically used a
generalized acoustic threshold based on received level to estimate the
onset of Level B harassment. These thresholds are 160 dB rms
(intermittent sources, which include impulsive sources) and 120 dB rms
(continuous sources). Airguns are impulsive sound sources; therefore,
the 160 dB rms threshold is appropriate for use in evaluating effects
from the specified activities.
Level A Harassment--NMFS's Technical Guidance for Assessing the
Effects of Anthropogenic Sound on
[[Page 63329]]
Marine Mammal Hearing (NMFS, 2018) identifies dual criteria to assess
the potential for auditory injury (Level A harassment) to occur for
different marine mammal groups (based on hearing sensitivity) as a
result of exposure to noise. The technical guidance identifies the
received levels, or thresholds, above which individual marine mammals
are predicted to experience changes in their hearing sensitivity for
all underwater anthropogenic sound sources, and reflects the best
available science on the potential for noise to affect auditory
sensitivity by:
Dividing sound sources into two groups (i.e., impulsive
and non-impulsive) based on their potential to affect hearing
sensitivity;
Choosing metrics that best address the impacts of noise on
hearing sensitivity, i.e., peak sound pressure level (peak SPL)
(reflects the physical properties of impulsive sound sources to affect
hearing sensitivity) and cumulative sound exposure level (cSEL)
(accounts for not only level of exposure but also duration of
exposure); and
Dividing marine mammals into hearing groups and developing
auditory weighting functions based on the science supporting that not
all marine mammals hear and use sound in the same manner.
The premise of the dual criteria approach is that, while there is
no definitive answer to the question of which acoustic metric is most
appropriate for assessing the potential for injury, both the received
level and duration of received signals are important to an
understanding of the potential for auditory injury. Therefore, peak SPL
is used to define a pressure criterion above which auditory injury is
predicted to occur, regardless of exposure duration (i.e., any single
exposure at or above this level is considered to cause auditory
injury), and cSEL is used to account for the total energy received over
the duration of sound exposure (i.e., both received level and duration
of exposure) (Southall et al., 2007; NMFS, 2018). As a general
principle, whichever criterion is exceeded first (i.e., results in the
largest isopleth) would be used as the effective injury criterion
(i.e., the more precautionary of the criteria). Note that cSEL acoustic
threshold levels incorporate marine mammal auditory weighting
functions, while peak pressure thresholds do not (i.e., flat or
unweighted). Weighting functions for each hearing group (e.g., low-,
mid-, and high-frequency cetaceans) are described in NMFS (2018).
NMFS (2018) recommends 24 hours as a maximum accumulation period
relative to cSEL thresholds. These thresholds were developed by
compiling and synthesizing the best available science, and are provided
in Table 3 below. The references, analysis, and methodology used in the
development of the thresholds are described in NMFS (2018), and more
information is available online at: www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance.
Table 3--Exposure Criteria for Auditory Injury for Impulsive Sources
------------------------------------------------------------------------
Cumulative sound
Hearing group Peak pressure \1\ exposure level
(dB) \2\ (dB)
------------------------------------------------------------------------
Low-frequency cetaceans........... 219 183
Mid-frequency cetaceans........... 230 185
High-frequency cetaceans.......... 202 155
------------------------------------------------------------------------
\1\ Referenced to 1 [mu]Pa; unweighted within generalized hearing range.
\2\ Referenced to 1 [mu]Pa\2\s; weighted according to appropriate
auditory weighting function.
NMFS considers these updated thresholds and associated weighting
functions to be the best available information for assessing whether
exposure to specific activities is likely to result in changes in
marine mammal hearing sensitivity.
Sound Field Modeling
BOEM's PEIS (BOEM, 2014a) provides information related to
estimation of the sound fields that would be generated by potential
geophysical survey activity on the mid- and south Atlantic OCS. We
provide a brief summary of that modeling effort here; for more
information, please see our Notice of Proposed IHAs. For full detail,
please see Appendix D of BOEM's PEIS (Zykov and Carr, 2014 in BOEM,
2014a). The acoustic modeling generated a three-dimensional acoustic
propagation field as a function of source characteristics and physical
properties of the ocean for later integration with marine mammal
density information in an animal movement model to estimate potential
acoustic exposures.
The authors selected 15 modeling sites throughout BOEM's mid-
Atlantic and south Atlantic OCS planning areas for use in modeling
predicted sound fields resulting from use of the airgun array. The
water depth at the sites varied from 30-5,400 m. Two types of bottom
composition were considered: Sand and clay, their selection depending
on the water depth at the source. Twelve possible sound speed profiles
for the water column were used to cover the variation of the sound
velocity distribution in the water with location and season. Twenty-one
distinct propagation scenarios resulted from considering different
sound speed profiles at some of the modeling sites. Two acoustic
propagation models were employed to estimate the acoustic field
radiated by the sound sources. A version of JASCO Applied Science's
Marine Operations Noise Model (MONM), based on the Range-dependent
Acoustic Model (RAM) parabolic-equations model, MONM-RAM, was used to
estimate the SELs for low-frequency sources (below 2 kHz) such as an
airgun array. For more information on sound propagation model types,
please see, e.g., Etter (2013). The model takes into account the
geoacoustic properties of the sea bottom, vertical sound speed profile
in the water column, range-dependent bathymetry, and the directivity of
the source. The directional source levels for the airgun array were
modeled using the Airgun Array Source Model (AASM) based on the
specifications of the source such as the arrangement and volume of the
guns, firing pressure, and depth below the sea surface. The modeled
directional source levels were used as the input for the acoustic
propagation model. For background information on major factors
affecting underwater sound propagation, please see Zykov and Carr
(2014).
The modeling used a 5,400 in\3\ airgun array as a representative
example. The array has dimensions of 16 x 15 m and consists of 18 air
guns placed in three identical strings of six air guns each (please see
Figure D-6 of Zykov and
[[Page 63330]]
Carr (2014)). The volume of individual air guns ranges from 105-660
in\3\. Firing pressure for all elements is 2,000 psi. The depth below
the sea surface for the array was set at 6.5 m. Please see Table 1 for
a comparison to the airgun arrays planned for use by the applicant
companies. Horizontal third-octave band directionality plots resulting
from source modeling are shown in Figure D-8 of Zykov and Carr (2014).
The estimated received levels are expressed in terms of the SEL metric
over the duration of a single source pulse. For the purposes of this
study, the SEL results were converted to the rms SPL metric using a
range dependent conversion coefficient.
Four depth regions were classified based on bathymetry: Shallow
continental shelf (<60 m); continental shelf (60-150 m); continental
slope (150-1,000 m); and deep ocean (>1,000 m). The modeling results
show that the largest threshold radii are typically associated with
sites in intermediate water depths (250 and 900 m). Low frequencies
propagate relatively poorly in shallow water (i.e., water depths on the
same order as or less than the wavelength). At intermediate water
depths, this stripping of low-frequency sound no longer occurs, and
longer-range propagation can be enhanced by the channeling of sound
caused by reflection from the surface and seafloor (depending on the
nature of the sound speed profile and sediment type). Table 4 shows
scenario-specific modeling results for distances to the 160 dB level;
results presented are for the 95 percent range to threshold.
Table 4--Modeling Scenarios and Site-Specific Modeled Threshold Radii From BOEM's PEIS
--------------------------------------------------------------------------------------------------------------------------------------------------------
Threshold radii
Scenario No. Site No.\1\ Water depth (m) Season Bottom type (m) \2\
--------------------------------------------------------------------------------------------------------------------------------------------------------
1............................. 1............................. 5,390 Winter.................. Clay.................... 4,969
2............................. 2............................. 2,560 Winter.................. Clay.................... 5,184
3............................. 3............................. 880 Winter.................. Sand.................... 8,104
4............................. 4............................. 249 Winter.................. Sand.................... 8,725
5............................. 5............................. 288 Winter.................. Sand.................... 8,896
6............................. 1............................. 5,390 Spring.................. Clay.................... 4,989
7............................. 6............................. 3,200 Spring.................. Clay.................... 5,026
8............................. 3............................. 880 Spring.................. Sand.................... 8,056
9............................. 7............................. 251 Spring.................. Sand.................... 8,593
10............................ 8............................. 249 Spring.................. Sand.................... 8,615
11............................ 1............................. 5,390 Summer.................. Clay.................... 4,973
12............................ 6............................. 3,200 Summer.................. Clay.................... 5,013
13............................ 3............................. 880 Summer.................. Sand.................... 8,095
14............................ 9............................. 275 Summer.................. Sand.................... 9,122
15............................ 10............................ 4,300 Fall.................... Clay.................... 5,121
16............................ 11............................ 3,010 Fall.................... Clay.................... 5,098
17............................ 12............................ 4,890 Fall.................... Clay.................... 4,959
18............................ 13............................ 3,580 Fall.................... Clay.................... 5,069
19............................ 3............................. 880 Fall.................... Sand.................... 8,083
20............................ 14............................ 100 Fall.................... Sand.................... 8,531
21............................ 15............................ 51 Fall.................... Sand.................... 8,384
-------------------------------------------------------------------------------------------------------------------------
Mean...................... .............................. ................. ........................ ........................ 6,838
--------------------------------------------------------------------------------------------------------------------------------------------------------
Adapted from Tables D-21 and D-22 of Zykov and Carr (2014).
\1\ Please see Figure D-35 of Zykov and Carr (2014) for site locations.
\2\ Threshold radii to 160 dB (rms) SPL, 95 percent range.
We provide this description of the modeling performed for BOEM's
PEIS as a general point of reference for the surveys, and also because
three of the applicant companies--TGS, CGG, and Western--directly used
these results to inform their exposure modeling, rather than performing
separate sound field modeling. As described by BOEM (2014a), the
modeled array was selected to be representative of the large airgun
arrays likely to be used by geophysical exploration companies in the
mid- and south Atlantic OCS. Therefore, we use the BOEM (2014a) results
as a reasonable proxy for those three companies (please see ``Detailed
Description of Activities'' for further description of the acoustic
sources planned for use by these three companies). ION and Spectrum
elected to perform separate sound field modeling efforts, and these are
described below.
ION--ION provided information related to estimation of the sound
fields that would be generated by their geophysical survey activity on
the mid- and south Atlantic OCS. We provide a brief summary of that
modeling effort here; for more information, please see our Notice of
Proposed IHAs. For full detail, please see Appendix A of ION's
application (Li, 2014; referred to hereafter as Appendix A of ION's
application). ION plans to use a 36-element airgun array with a 6,420
in\3\ total firing volume (please see ``Detailed Description of
Activities'' for further description of ION's acoustic source). The
modeling assumed that ION would operate from July to December. Sixteen
representative sites were selected along survey track lines planned by
ION for use in modeling predicted sound fields resulting from use of
the airgun array (see Figure 2 in Appendix A of ION's application for
site locations). Two acoustic propagation models were employed to
estimate the acoustic field radiated by the sound sources. As was
described above for BOEM's PEIS, the acoustic signature of the airgun
array was predicted using AASM and MONM was used to calculate the sound
propagation and acoustic field near each defined site. The modeling
process follows generally that described previously for BOEM's PEIS.
Key differences are the characteristics of the acoustic source (see
Table 1), locations of the modeled sites, and the use of a restricted
set of sound velocity profiles (e.g., fall and winter). Site-specific
modeling results for distances to the 160 dB rms level were presented
in Table 8 of our Notice of Proposed IHAs and are not reprinted here;
mean result for the
[[Page 63331]]
95 percent range to threshold was 5,836 m.
Spectrum--Spectrum provided information related to estimation of
the sound fields that would be generated by their geophysical survey
activity on the mid- and south Atlantic OCS. We provide a brief summary
of that modeling effort here; for more information, please see our
Notice of Proposed IHAs. For full detail, please see Appendix A of
Spectrum's application (Frankel et al., 2015; referred to hereafter as
Appendix A of Spectrum's application). Spectrum plans to use a 32-
element airgun array with a 4,920 in\3\ total firing volume (please see
``Detailed Description of Activities'' for further description of
Spectrum's acoustic source). Array characteristics were input into the
GUNDALF model to calculate the source level and predict the array
signature. The directivity pattern of the airgun array was calculated
using the beamforming module in the CASS[hyphen]GRAB acoustic
propagation model. These models provided source input information for
the range[hyphen]dependent acoustic model (RAM), which was then used to
predict acoustic propagation and estimate the resulting sound field.
The RAM model creates frequency-specific, three-dimensional directivity
patterns (sound field) based upon the size and location of each airgun
in the array. As described previously, physical characteristics of the
underwater environment (e.g., sound velocity profile, bathymetry,
substrate composition) are critical to understanding acoustic
propagation; 16 modeling locations were selected that span the acoustic
conditions of the survey area. Spectrum elected to use sound velocity
profiles for winter and spring and assumed that half of the survey
would occur in winter and half in spring. Site-specific modeling
results for distances to the 160 dB rms level were presented in Table 9
of our Notice of Proposed IHAs and are not reprinted here; mean result
for the 95 percent range to threshold was 9,775 m.
Marine Mammal Density Information
The best available scientific information was considered in
conducting marine mammal exposure estimates (the basis for estimating
take). Historically, distance sampling methodology (Buckland et al.,
2001) has been applied to visual line-transect survey data to estimate
abundance within large geographic strata (e.g., Fulling et al., 2003;
Mullin and Fulling, 2004; Palka, 2006). Design-based surveys that apply
such sampling techniques produce stratified abundance estimates and do
not provide information at appropriate spatiotemporal scales for
assessing environmental risk of a planned survey. To address this issue
of scale, efforts were developed to relate animal observations and
environmental correlates such as sea surface temperature in order to
develop predictive models used to produce fine-scale maps of habitat
suitability (e.g., Waring et al., 2001; Hamazaki, 2002; Best et al.,
2012). However, these studies generally produce relative estimates that
cannot be directly used to quantify potential exposures of marine
mammals to sound, for example. A more recent approach known as density
surface modeling couples traditional distance sampling with
multivariate regression modeling to produce density maps predicted from
fine-scale environmental covariates (e.g., DoN, 2007; Becker et al.,
2014; Roberts et al., 2016).
At the time the applications were initially developed, the best
available information concerning marine mammal densities in the survey
area was the U.S. Navy's Navy Operating Area (OPAREA) Density Estimates
(NODEs) (DoN, 2007). These habitat-based cetacean density models
utilized vessel-based and aerial survey data collected by NMFS from
1998-2005 during broad-scale abundance studies. Modeling methodology is
detailed in DoN (2007). A more advanced cetacean density modeling
effort, described in Roberts et al. (2016), was ongoing during initial
development of the applications, and the model outputs were made
available to the applicant companies. All information relating to this
effort was made publicly available in March 2016.
Roberts et al. (2016) provided several key improvements with
respect to the NODEs effort, by incorporating additional aerial and
shipboard survey data from NMFS and from other organizations collected
over the period 1992-2014, incorporating 60 percent more shipboard and
500 percent more aerial survey hours than did NODEs; controlling for
the influence of sea state, group size, availability bias, and
perception bias on the probability of making a sighting; and modeling
density from an expanded set of eight physiographic and 16 dynamic
oceanographic and biological covariates. There are multiple reasons why
marine mammals may be undetected by observers. Animals are missed
because they are underwater (availability bias) or because they are
available to be seen, but are missed by observers (perception and
detection biases) (e.g., Marsh and Sinclair, 1989). Negative bias on
perception or detection of an available animal may result from
environmental conditions, limitations inherent to the observation
platform, or observer ability. Therefore, failure to correct for these
biases may lead to underestimates of cetacean abundance (e.g., NMFS's
SAR estimates fail to correct for availability bias). Use of additional
data was used to improve detection functions for taxa that were rarely
sighted in specific survey platform configurations. The degree of
underestimation would likely be particularly high for species that
exhibit long dive times or are cryptic, such as sperm whales or beaked
whales. In summary, consideration of additional survey data and an
improved modeling strategy allowed for an increased number of taxa
modeled and better spatiotemporal resolutions of the resulting
predictions. In general, we consider the models produced by Roberts et
al. (2016) to be the best available source of data regarding cetacean
density in the Atlantic. More information, including the model results
and supplementary information for each model, is available at
seamap.env.duke.edu/models/Duke-EC-GOM-2015/.
Aerial and shipboard survey data produced by the Atlantic Marine
Assessment Program for Protected Species (AMAPPS) program provides an
additional source of information regarding marine mammal presence in
the survey areas. These surveys represent a collaborative effort
between NMFS, BOEM, and the Navy. Although the cetacean density models
described above do include survey data from 2010-14, the AMAPPS data
for those years was not made available to the model authors. Future
model updates will incorporate these data, but currently the AMAPPS
data comprise a separate source of information (e.g., NMFS, 2010a,
2011, 2012, 2013a, 2014, 2015a).
Cetacean density predictions provided by the Roberts et al. (2016)
models are in most cases limited to the U.S. EEZ. However, the planned
survey areas extend beyond the EEZ out to 350 nmi. Because specific
modeling results were not available for this region at the time the
exposure estimates were developed, the Roberts et al. (2016) model
predictions were extrapolated out to the additional area (described in
further detail below). Newer modeling products regarding cetacean
densities in areas of the western North Atlantic beyond the EEZ became
available (Mannocci et al., 2017) following development of the exposure
estimates; however, this information was not reasonably available to
the applicants in
[[Page 63332]]
developing their applications or to NMFS in preparing the Notice of
Proposed IHAs. Therefore, we retain use of the extrapolated density
values from Roberts et al. (2016) in estimating potential exposures in
the region beyond the EEZ; this approach remains reasonably
representative of cetacean densities in the portion of the specific
geographic region outside the EEZ.
North Atlantic Right Whale--Following publication of our Notice of
Proposed IHAs, we became aware of an effort by Roberts et al. to update
certain density models, including for the North Atlantic right whale.
In contrast to other new information that was not reasonably available
to us in developing the exposure estimates discussed herein (e.g.,
Mannocci et al., 2017 and additional Roberts et al. model revisions
(discussed below)), we determined that the revised North Atlantic right
whale models represent a significant improvement to the available
information. These updates greatly expanded the dataset used to derive
density outputs, especially within the action area, as they
incorporated both AMAPPs data as well as data from aerial surveys
conducted by several organizations in the southeast United States. By
including these additional data sources, the number of right whale
sightings used to inform the models within the action area increased by
over 2,500 sightings (approximately 40 sightings in the 2015 model
versus approximately 2,560 sightings in the 2017 model) (Roberts et
al., 2017). In addition, the updated models incorporated several
improvements to minimize known biases and used an improved seasonal
definition that more closely aligns with right whale biology.
Importantly, the updated model outputs showed a strong relationship
between right whale abundance in the action area and distance to shore
out to approximately 80 km (Roberts et al., 2017)--the same
relationship was indicated as being out to approximately 50 km by the
previous model version (Roberts et al., 2016). As a result of these
significant model improvements and in context of the significant
concern regarding North Atlantic right whale status, we determined it
necessary to produce revised exposure estimates for the North Atlantic
right whale (described in further detail below). As stated by the
authors, their goal in updating the right whale model was to re-examine
all aspects of the model and make as many improvements as possible.
This updated model represents the best available scientific information
regarding North Atlantic right whale density and distribution.
We note that, in addition to the models for North Atlantic right
whales, Roberts et al. (2017) presented updated models for 10
additional taxa (fin, humpback, minke, sei, and sperm whales; separate
models for Cuvier's, Mesoplodont, and unidentified beaked whales; pilot
whales; and harbor porpoise). While these models incorporate several
improvements (additional data (although mostly outside of the action
area), new seasonal definitions, updates to better correct for known
biases), we evaluated the model outputs as being generally similar to
those produced by Roberts et al. (2016). Thus, while the Roberts et al.
(2017) models for these additional species likely represent minor
improvements over the Roberts et al. (2016) models for these species,
they are unlikely to result in meaningful differences if used in an
exposure analysis. That is, we consider both the Roberts et al. (2016)
and Roberts et al. (2017) model outputs the best available density
estimates for these additional species, and estimates of exposure based
on the outputs of one model are unlikely to be meaningfully different
than estimates based on outputs from the other. Therefore, because
these revised models were not available to us at the time of initial
development of the exposure estimates and do not represent a
significant improvement in the state of available scientific
information, as do the updated right whale models, we did not request
these updated models from the authors and retain use of the 2015 model
version for these taxa.
Description of Exposure Estimates
Here, we provide applicant-specific descriptions of the processes
employed to estimate potential exposures of marine mammals to given
levels of received sound. The discussions provided here are specific to
estimated exposures at or above the criterion for Level B harassment
(i.e., 160 dB rms); we provide a separate discussion below regarding
our consideration of potential Level A harassment. We provide a brief
summary of the exposure modeling process performed for BOEM's PEIS as a
point of reference; for more information, please see our Notice of
Proposed IHAs. For full detail, see Appendix E of the PEIS (BOEM,
2014a).
This description builds on the description of sound field modeling
provided earlier in this section and in Appendix D of BOEM's PEIS. As
described previously, 21 distinct acoustic propagation regions were
defined. Reflecting seasonal differences in sound velocity profiles,
these regions were specific to each season. Using the NODEs data, the
average density of each species was then numerically determined for
each region. However, the NODEs models do not provide outputs for the
extended continental shelf areas seaward of the EEZ; therefore, known
density information at the edge of the area modeled by NODEs was
extrapolated to the remainder of the study area.
The results of the acoustic modeling exercise (i.e., estimated 3D
sound field) and the region-specific density estimates were then input
into MAI's Acoustic Integration Model (AIM). AIM is a software package
developed to predict the exposure of receivers (e.g., an animal) to any
stimulus propagating through space and time through use of a four-
dimensional, individual-based, Monte Carlo-based statistical model.
Within the model, simulated marine animals (i.e., animats) may be
programmed to behave in specific ways on the basis of measured field
data. An animat movement engine controls the geographic and vertical
movements (e.g., speed and direction) of sound sources and animats
through four dimensions (time and space) according to user inputs.
Species-specific animats were created with programmed behavioral
parameters describing dive depth, surfacing and dive durations,
swimming speed, course change, and behavioral aversions (e.g., water
too shallow). The programmed animats were then randomly distributed
over a given bounded simulation area. Because the exact positions of
sound sources and animals are not known in advance for proposed
activities, multiple runs of realistic predictions are used to provide
statistical validity to the simulated scenarios. Each species-specific
simulation is seeded with a given density of animats. A separate
simulation was created and run for each combination of location,
movement pattern, and marine mammal species.
A model run consists of a user-specified number of steps forward in
time, in which each animat is moved according to the rules describing
its behavior. For each time step of the model run, the received sound
levels at each animat (i.e., each marine mammal) are calculated. AIM
returns the movement patterns of the animats, and the received sound
levels are calculated separately using the given acoustic propagation
predictions at different locations. At the end of each time step, an
animat ``evaluates'' its environment, including its 3D location, the
time, and any received sound level.
[[Page 63333]]
Animat positions relative to the acoustic source (i.e., range,
bearing, and depth) were used to extract received level estimates from
the acoustic propagation modeling results. The source levels, and
therefore subsequently the received levels, include the embedded
corrections for signal pulse length and M-weighting. M-weighting is a
type of frequency weighting curve intended to reflect the differential
potential for sound to affect marine mammals based on their sensitivity
to the particular frequencies produced (Southall et al., 2007). Please
see Appendix D of BOEM's PEIS for further description of the
application of M-weighting filters. For each bearing, distance, and
depth from the source, the received level values were expressed as SPLs
(rms) with units of dB re 1[mu] Pa. These are then converted back to
intensity and summed over the duration of the exercise to generate an
integrated energy level, expressed in terms of dB re 1 [mu]Pa\2\-sec or
dB SEL. The number of animats per species that exceeded a given
criterion (e.g., 160 dB rms) may then be determined, and these results
scaled according to the relationship of model-to-real world densities
per species. That is, the exposure results are corrected using the
actual species- and region-specific density derived from the density
model outputs (as described above) to give real-world estimates of
exposure to sound exceeding a given received level.
As noted previously, the NODEs models (DoN, 2007) provided the best
available information at the time of initial development for these
applications. Outputs of the cetacean density models described by
Roberts et al. (2016) were subsequently made available to the applicant
companies, which, with the exception of CGG, had previously submitted
applications. Two applicants (TGS and Western) elected to consider the
new information and produced revised applications accordingly. CGG used
the Roberts et al. (2016) models in developing their application. Two
applicants (Spectrum and ION) declined to use the Roberts et al. (2016)
density models. However, we worked with MAI--which performed the
initial exposure modeling provided in the Spectrum and ION
applications--to produce revised exposure estimates utilizing the
outputs of the Roberts et al. (2016) density models.
In order to revise the exposure estimates for Spectrum and ION, we
first extracted appropriate density estimates from the Roberts et al.
(2016) model outputs. Because both Spectrum and ION used modeling
processes conceptually similar to that described above for BOEM's PEIS,
these density estimates would replace those previously derived from the
NODEs models in rescaling the exposure estimation results from those
derived from animal movement modeling using a user-specified density.
The steps involved in calculating mean marine mammal densities over the
21 modeling areas used in both BOEM's PEIS and the applications were
described in our Notice of Proposed IHAs, and are not repeated here. As
was the case for the NODEs model outputs, the Roberts et al. (2016)
model outputs are restricted to the U.S. EEZ. Therefore, we similarly
extended the edge densities to cover the area outside of the data
extent. This process was also described in our Notice of Proposed IHAs,
and is not repeated here.
Spectrum--Spectrum's sound field estimation process was previously
described, and their exposure modeling process is substantially similar
to that described above for BOEM's PEIS. Spectrum's exposure modeling
process was described in full in our Notice of Proposed IHAs; please
see that document for more detail. As described previously, Spectrum
limited their analysis to winter and spring seasons and therefore used
only ten of the 21 seasonal propagation acoustic regions. Half of the
survey activity was assumed to occur in winter and half in spring.
In summary, the original exposure results were obtained using AIM
to model source and animat movements, with received SEL for each animat
predicted at a 30-second time step. This predicted SEL history was used
to determine the maximum SPL (rms or peak) and cSEL for each animat,
and the number of exposures exceeding relevant criteria recorded. The
number of exposures are summed for all animats to get the number of
exposures for each species, with that summed value then scaled by the
ratio of real-world density to the model density value. The final
scaling value was the ratio of the length of the modeled survey line to
the length of survey line in each modeling region. The exposure
estimates provided in Spectrum's application were based on the NODEs
model outputs. In order to make use of the best available information
(i.e., Roberts et al. (2016)), we extracted species- and region-
specific density values as described above. These were provided to MAI
in order to rescale the original exposure results produced using the
seeded animat density; revised exposure estimates are shown in Table 6.
As stated above, Spectrum notified NMFS on June 26, 2018, of a
modification to their survey plan. Note that analysis corresponding
with Spectrum's original survey plan is retained here, in ``Estimated
Take.'' Please see ``Spectrum Survey Plan Modification'' for further
information and for revised (and authorized) take numbers (Table 17)
relating to Spectrum's modified survey plan.
ION--ION's sound field estimation process was previously described,
and their exposure modeling process is substantially similar to that
described above for BOEM's PEIS (and for Spectrum). ION's exposure
modeling process was described in full in our Notice of Proposed IHAs;
please see that document for more detail. The same acoustic propagation
regions described for BOEM's PEIS were used by ION for exposure
modeling; however, ION limited their analysis to summer and fall
seasons and therefore used only 11 of the 21 regions. Whichever season
returned the higher number of estimated exposures for a given species
was assumed to be the season in which the survey occurred, i.e., ION's
requested take authorization corresponds to the higher of the two
seasonal species-specific exposure estimates.
In summary, the original exposure results were obtained using AIM
to model source and animat movements, with received SEL for each animat
predicted at a 30-second time step. This predicted SEL history was used
to determine the maximum SPL (rms or peak) and cSEL for each animat,
and the number of exposures exceeding relevant criteria recorded. The
number of exposures are summed for all animats to get the number of
exposures for each species, with that summed value then scaled by the
ratio of real-world density to the model density value. The final
scaling value was the ratio of the length of the modeled survey line to
the length of survey line in each modeling region. As described above,
the exposure estimates provided in ION's application were based on the
NODEs model outputs. In order to make use of the best available
information (i.e., Roberts et al. (2016)), we extracted species- and
region-specific density values as described above. These were provided
to MAI in order to rescale the original exposure results produced using
the seeded animat density; revised exposure estimates are shown in
Table 6.
TGS--TGS did not conduct their own sound field modeling, instead
relying on the sound field estimates provided by BOEM (2014a). For
purposes of exposure modeling, TGS considered threshold radii for three
depth bins: <880 m, 880-2,560 m, >2,560 m (note that there are no sound
field modeling sites at depths between 880-2,560 m).
[[Page 63334]]
When considering the 21 modeling scenarios across the 15 sites,
threshold radii shown in Table 4 break down evenly with 11 at depths
<=880 m (mean threshold radius of 8,473 m) and ten at depths >=2,560 m
(mean threshold radius of 5,040 m). Therefore, the overall mean for all
scenarios of 6,838 m was used for estimating potential exposures for
track lines occurring in water depths of 880-2,560 m.
Regarding marine mammal occurrence, TGS considered both the Roberts
et al. (2016) density models as well as the AMAPPS data. TGS stated
that there are aspects of the Roberts et al. (2016) methodology that
limit the model outputs' applicability to estimating marine mammal
exposures to underwater sound and determined it appropriate to develop
their own density estimates for certain species using AMAPPS data.
As stated above, we believe the density models described by Roberts
et al. (2016) provide the best available information at the time of our
evaluation and recommend their use for species other than those
expected to be extremely rare in a given area. However, TGS used the
most recent observational data available in their alternative take
estimation process conducted for seven of the affected species or
groups. We acknowledge their concerns regarding use of predictive
density models for species with relatively few observations in the
survey area, e.g., that model-derived density estimates must be applied
cautiously on a species-by-species basis with the recognition that in
some cases the out-of-bound predictions could produce unrealistic
results (Becker et al., 2014). Further, use of uniform (i.e.,
stratified) density models assumes a given density over a large
geographic range which may include areas where the species has rarely
or never been observed. For the seven species or species groups that
TGS applied their alternative approach to (described below), five are
modeled in whole or part through use of stratified models. We also
acknowledge (as do Roberts et al. (2016)) that predicted habitat may
not be occupied at expected densities or that models may not agree in
all cases with known occurrence patterns, and that there is uncertainty
associated with predictive habitat modeling (e.g., Becker et al., 2010;
Forney et al., 2012). We determined that TGS' alternative approach (for
seven species or species groups) is acceptable and, importantly, we
recognize that there is no model or approach that is always the most
appropriate and that there may be multiple approaches that may be
considered acceptable (e.g., Box, 1979). Further detailed discussion on
these topics was provided in our Notice of Proposed IHAs, and is not
repeated here.
In summary, TGS described the following issues in support of their
development of an alternative approach for certain species:
There are very few sightings of some species despite
substantial survey effort;
The modeling approach extrapolates based on habitat
associations and assumes some species' occurrence in areas where they
have never been or were rarely documented (despite substantial effort);
In some cases, uniform density models spread densities of
species with small sample sizes across large areas of the EEZ without
regard to habitat, and;
The most recent NOAA shipboard and aerial survey data
(i.e., AMAPPS) were not included in model development.
As a result of their general concerns regarding suitability of
model outputs for exposure estimation, TGS developed a scheme related
to the number of observations in the dataset available to Roberts et
al. (2016) for use in developing the density models. Extremely rare
species (i.e., less than four sightings in the survey area) were
considered to have a very low probability of encounter, and it was
assumed that the species might be encountered once. Therefore, a single
group of the species was considered as expected to be exposed to sound
exceeding the 160 dB rms harassment criterion. We agree with this
approach for rarely occurring species and adopted it for all
applicants, as described below.
As described previously, marine mammal abundance has traditionally
been estimated by applying distance sampling methodology (Buckland et
al., 2001) to visual line-transect survey data. Buckland et al. (2001)
recommend a minimum sample size of 60-80 sightings to provide
reasonably robust estimates of density and abundance to fit the
mathematical detection function required for this estimation; smaller
sample sizes result in higher variance and thus less confidence and
less accurate estimates. While we agree that TGS' approach is a
reasonable one, we also note that the Buckland et al. (2001)
recommendation that sample size should generally be at least 60-80
should be considered as general guidance but not an absolute rule.
Buckland et al. (2001) provide no theoretical proof for it and, in
fact, it has not been followed as a rule in practice. Miller and Thomas
(2015) provide an example where a detection function fitted to 30
sightings resulted in a detection function with low bias. NMFS's line-
transect abundance estimates are in some cases based on many fewer
sightings, e.g., stock assessments based on Palka (2012). For species
meeting the Buckland et al. guideline within the survey area, TGS used
Roberts et al. (2016)'s model. For species with fewer sightings (but
with greater than four sightings in the survey area), TGS used what
they refer to as ``Line Transect Theory'' in conjunction with AMAPPS
data to estimate species density within the assumed 160 dB rms zone of
ensonification.
Nine species or species groups met TGS' requirement of having at
least 60 sightings within the survey area in the dataset available to
Roberts et al. (2016): Atlantic spotted dolphin, pilot whales, striped
dolphin, beaked whales, bottlenose dolphin, Risso's dolphin, common
dolphin, sperm whale, and humpback whale. The steps involved in the
exposure estimation process for these species was described in full in
our Notice of Proposed IHAs and is not repeated here.
Seven species or species groups met TGS' criterion for conducting
exposure modeling, but did not have the recommended 60 sightings in the
survey area: Minke whale, fin whale, Kogia spp., harbor porpoise,
pantropical spotted dolphin, clymene dolphin, and rough-toothed
dolphin. For these species, TGS did not feel use of the density models
was appropriate and developed a method using the available data instead
(i.e., AMAPPS data as well as data considered by Roberts et al. (2016),
excluding results of surveys conducted entirely outside of an area
roughly coincident with the planned survey area); species-specific
rationale is provided in section 6.3 of TGS' application. Please see
section 6.3 of TGS' application for further details regarding the
AMAPPS survey effort considered by TGS. Table 6-1 in TGS' application
summarizes the AMAPPS data available for consideration by the authors.
The steps involved in the exposure estimation process for these species
was described in full in our Notice of Proposed IHAs and is not
repeated here (see Table 6-4 in TGS' application for numerical process
details).
TGS initially proposed use of a mitigation source (i.e., 90-in\3\
airgun) for line turns and transits not exceeding three hours and
produced exposure estimates specific to use of the mitigation source.
As described in ``Mitigation,'' we do not allow use of the mitigation
source; therefore, exposure estimates specific to use of a mitigation
[[Page 63335]]
gun would not actually occur. In their application, TGS provided
exposure estimates specific to use of the full-power array and to use
of the mitigation gun for the seven species for which the alternative
approach was followed, but not for the nine species whose exposure
estimates are based on the Roberts et al. (2016) density models (for
the latter group, only a combined total was provided). Therefore, in
our Notice of Proposed IHAs, we did not include mitigation gun exposure
estimates for the former group but did for the latter group, noting
exposure estimates for those nine species were slightly overestimated.
However, following publication of our Notice of Proposed IHAs, TGS
provided a breakdown for these species according to full-power array
versus mitigation source; therefore, we have removed the estimates
associated with use of the mitigation source for all species. Take
authorization numbers provided for TGS (Table 6) reflect this
appropriate adjustment.
Western--Western's approach to estimating potential marine mammal
exposures to underwater sound was identical to that described above for
TGS; therefore, we do not provide a separate description for Western.
Western also initially proposed use of a mitigation source for line
turns and transits not exceeding three hours and produced exposure
estimates specific to use of the mitigation source. Like TGS, Western's
application provided information specific to use of the full-power
array versus the mitigation source for the seven species for which the
alternative approach was followed, but not for the nine species whose
exposure estimates are based on the Roberts et al. (2016) density
models (for the latter group, only a combined total was provided).
However, unlike TGS, Western did not provide additional information
following publication of our Notice of Proposed IHAs. Therefore,
mitigation gun exposure estimates are included in the total for the
latter group, and exposure estimates for those nine species are
slightly overestimated.
CGG--CGG used applicable results from BOEM's sound field modeling
exercise in conjunction with the outputs of models described by Roberts
et al. (2016) to inform their estimates of likely acoustic exposures.
CGG's exposure modeling process was described in full in our Notice of
Proposed IHAs; please see that document for more detail. Considering
only the BOEM modeling sites that are in or near CGG's survey area
provided a mean radial distance to the 160 dB rms criterion of 6,751 m
(range 5,013-8,593 m). Taxon-specific model outputs, averaged over the
six-month period planned for the survey (i.e., July-December) where
relevant, were used with the assumed ensonification zone to provide
estimates of marine mammal exposures to noise above the 160 dB rms
threshold. Similar to other applicants, CGG performed an interpolation
analysis to estimate density values for the portion of planned survey
area outside the EEZ.
North Atlantic Right Whale--As described above, given the current
status of North Atlantic right whales, we re-evaluated available
information subsequent to public review of our proposed IHAs. Finding
that significant improvements were available to us, we determined it
appropriate to re-estimate acoustic exposures specifically for right
whales using the updated models. To do so, we relied on the sound field
modeling results provided in BOEM's 2014 PEIS (see description above
and Appendix D in BOEM (2014a)), as was previously done by TGS, CGG,
and Western in their IHA applications. Using site- and season-specific
radii to the 160 dB rms threshold (95 percent range, see Table 4 above
or Table D-22 in BOEM (2014a)) and the total amount of trackline
planned by each company within the acoustic modeling regions specified
in BOEM's 2014 PEIS (see Appendix E, Table E-5 and Figures E-11 to E14
in BOEM (2014a)), we calculated monthly, region-specific ensonified
areas for each company as if their entire survey tracklines were
completed in each month. Then, using the updated 2017 density model
outputs (Roberts et al., 2017), we calculated average monthly regional
right whale densities, which were then multiplied by the monthly
ensonified areas. Finally, these data were averaged (annually or
according to the planned operating window where appropriate) to
estimate the average total exposure of North Atlantic right whales. In
this way, we incorporated the seasonal variation in density of right
whales since we do not know the exact distribution of survey effort
within each company's operating window.
Importantly, in these calculations we took into account the time-
area restrictions specified in ``Mitigation.'' For the year-round
closure areas, data (i.e., ensonified areas and North Atlantic right
whale densities) were not used to formulate exposure estimates since
surveys would be completely prohibited within these areas. In the
seasonal restriction areas, only data from months when the areas are
open were used in calculating the exposure estimates. The final
resulting exposure estimates then are based on the best available
information on North Atlantic right whale densities within the action
area (Roberts et al., 2017), fully take into account all time-area
restrictions, and are specific to each company's tracklines and planned
operating window (if specified). Take estimates shown in Table 6 for
North Atlantic right whales reflect this analysis, and replace those
previously estimated using different information and specified in our
Notice of Proposed IHAs.
Time-Area Restrictions--Following review of public comments, we
conducted an analysis of expected take avoided due to implementation of
the time-area restrictions described in ``Mitigation.'' To do this, we
took an approach related to that previously described for right whales.
In brief, we started with the existing take estimates as described in
our Notice of Proposed IHAs and then calculated the take that would be
avoided due to the planned restrictions. We then subtracted this from
the originally proposed take to get our final take estimates. As
described below, we took a slightly different approach for the sperm
whale as compared with other species in that we accounted for the
seasonal restriction of Area #4 (the ``Hatteras and North''
restriction; see ``Mitigation''). We did this because the area was
designed in part specifically to benefit sperm whales, and because
density model outputs are provided at monthly resolution for sperm
whales, whereas density model outputs are provided at only annual
resolution for beaked whales and pilot whales (Area #4 was also
designed specifically to benefit these species). Take avoided due to
seasonal restrictions, versus year-round closures, cannot be calculated
for species for which only annual density outputs are available. For
those species with monthly data availability but for which the seasonal
restriction was not designed, we determined that the analysis was
unlikely to result in meaningful changes to the take estimates.
For sperm whales, we calculated the monthly density within each
year-round closure area using the Roberts et al. (2016) model outputs
and calculated the monthly ensonified area within each year-round
closure for each company based on their planned tracklines and the
radii to the 160 dB rms threshold. We then multiplied these monthly
numbers by each other to estimate the monthly take avoided and,
finally, computed the annual average of these avoided takes to estimate
the overall take that would be avoided due to the year-round closures.
For the seasonal
[[Page 63336]]
restrictions, only Area #4 (the ``Hatteras and North'' restriction; see
``Mitigation'') was accounted for since it is the only seasonal
restriction designed specifically to protect sperm whales. While we
considered accounting for the North Atlantic right whale seasonal
restriction, we opted not to since it primarily protects shallower
waters where sperm whales are less likely to be found, and the added
complication of incorporating the restriction was unlikely to result in
meaningful changes to the overall take estimates for sperm whales. To
account for Area #4, we calculated the change in take due to the
restriction in a similar fashion to the year-round closures above,
except that instead of calculating the change in take based on an
annual average, we calculated the difference between the average take
for when the area is open and when the area is closed in order to
calculate the overall change in take due to restricting surveys within
this area. As before, for these calculations we took into account
specific survey timing where relevant but otherwise assumed the surveys
could happen at any time of the year. The combined year-round and
seasonal avoided takes were then subtracted from the originally
proposed take authorizations described in our Notice of Proposed IHAs
to calculate the final take estimates for sperm whales.
For other species, a simpler approach was taken. First, we did not
account for any seasonal restrictions, either because sufficient data
is not available or because the seasonal restrictions' benefit in
protecting species for which they were not specifically designed is
unclear. Second, we did not recalculate density estimates specifically
within the year-round closures, but instead relied on density estimates
derived from the Roberts et al. (2016) model outputs for each acoustic
modeling region used in BOEM's 2014 PEIS. Using these density
estimates, we then followed the same procedure detailed above for sperm
whales (multiplied monthly or seasonal densities by monthly or seasonal
ensonified area, and compute annual or operating window average) to
estimate the take that would be avoided due to the year-round closures.
These avoided takes were then subtracted from the originally proposed
take authorizations described in our Notice of Proposed IHAs to
calculate the final take estimates.
Level A Harassment
All requests for IHAs described herein were received prior to
NMFS's original 2016 technical guidance and, therefore, did not reflect
consideration of the currently best available information regarding the
potential for auditory injury. In our Notice of Proposed IHAs, we
described a process by which we estimated expected takes by Level A
harassment in reflection of both NMFS's technical guidance and the
specific survey characteristics (i.e., actual line-kms and specific
airgun arrays planned for use) using modeled auditory injury exposure
results found in BOEM's 2014 PEIS. The PEIS results were based on both
the Southall et al. (2007) guidance (a precursor to NMFS's technical
guidance) and the historical 180-dB rms criterion (which provides
information relevant to a comparison to the likelihood of injurious
exposure resulting from peak pressure). That process was described in
our Notice of Proposed IHAs and is not repeated here. However,
following review of public comments, we determined it appropriate to
re-evaluate the analysis, as described below.
In our Notice of Proposed IHAs, we acknowledged that the Level A
exposure estimates provided therein--based on adjustments made to the
results provided in BOEM's PEIS--were a rough approximation of
potential exposures, with multiple limitations in reflection of the
available information or lack thereof. For example, specific trackline
locations planned by the applicant companies may differ somewhat from
those considered in BOEM's PEIS, although it is likely that all
portions of the survey area are considered in the PEIS analysis. More
importantly, the PEIS exposure estimates were based on outputs of the
NODEs models (DoN, 2007) available for BOEM's analysis versus the
density models subsequently provided by Roberts et al. (2016), which we
believe represent the best available information for purposes of
exposure estimation. In addition, we noted that we did not attempt to
approximate the probability of marine mammal aversion or to incorporate
the effects of mitigation on the likelihood of Level A harassment.
Following review of public comments, we reconsidered the likelihood of
potential auditory injury, specific to each hearing group (i.e., low-
frequency, mid-frequency, and high-frequency), and re-evaluated the
specific Level A harassment estimates presented in our Notice of
Proposed IHAs. Here, we provide a revised analysis of likely takes by
Level A harassment.
Specifically, we determined that there is a low likelihood of take
by Level A harassment for any species, and that this likelihood is
primarily influenced by the specific hearing group. For mid- and high-
frequency cetaceans, potential auditory injury would be expected to
occur on the basis of instantaneous exposure to peak pressure output
from an airgun array, leading to a relatively straightforward
consideration of the Level A harassment zone as an areal subset of the
Level B harassment zone and, therefore, takes by Level A harassment as
a subset of the previously enumerated takes by Level B harassment.
However, for mid-frequency cetaceans, additional considerations of the
small calculated Level A harassment zone size in conjunction with the
properties of sound fields produced by arrays in the near field versus
far field lead to a logical conclusion that Level A harassment is so
unlikely for species in this hearing group as to be discountable. For
low-frequency cetaceans, consideration of the likely potential for
auditory injury is not straightforward, as such exposure would occur on
the basis of the accumulation of energy output over time by an airgun
array. Additional factors, such as the relative motion of source and
receiver and the implementation of mitigation lead us to conclude that
a quantitative evaluation of such potential, in light of the available
information, does not make sense. Our evaluations for all three hearing
groups are detailed below.
As part of the exposure estimation process described in our Notice
of Proposed IHAs, we calculated expected injury zones specific to each
applicant's array for each hearing group relative to injury criteria
for both the cSEL and peak pressure metrics. The results of this
process, shown in Table 5, remain valid and were used to inform the
revised estimates of take by Level A harassment described herein. For
the cSEL metric, in order to incorporate the technical guidance's
weighting functions over an array's full acoustic band, we obtained
unweighted spectrum data (modeled in 1 Hz bands) for a reasonably
equivalent acoustic source (i.e., a 36-airgun array with total volume
of 6,600 in\3\). Using these data, we made adjustments (dB) to the
unweighted spectrum levels, by frequency, according to the weighting
functions for each relevant marine mammal hearing group. We then
converted these adjusted/weighted spectrum levels to pressures
(micropascals) in order to integrate them over the entire broadband
spectrum, resulting in broadband weighted source levels by hearing
group that could be directly incorporated within NMFS's User
Spreadsheet (i.e., override the Spreadsheet's more simple weighting
factor adjustment).
When NMFS (2016) was published, in recognition of the fact that
appropriate
[[Page 63337]]
isopleth distances could be more technically challenging to predict
because of the duration component in the new thresholds, NMFS developed
a User Spreadsheet that includes tools to help predict a simple
isopleth that can be used in conjunction with marine mammal density to
help predict exposures. For mobile sources, such as the surveys
considered here, the User Spreadsheet predicts the closest distance at
which a stationary animal would not incur PTS if the sound source
traveled by the animal in a straight line at a constant speed (the
``safe distance'' methodology discussed below). For more information
about the User Spreadsheet, please see www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance.
Using the User Spreadsheet's ``safe distance'' methodology for
mobile sources (described by Sivle et al., 2014) with the hearing
group-specific weighted source levels, and inputs assuming spherical
spreading propagation, a source velocity of 4.5 kn, shot intervals
specified by the applicants, and pulse duration of 100 ms, we then
calculated potential radial distances to auditory injury zones relative
to the cSEL metric. We also calculated potential radial distances to
auditory injury zones on the basis of maximum peak pressure using
values provided by the applicants (Table 1) and assuming a simple model
of spherical spreading propagation. We note that our Notice of Proposed
IHAs contained an error. On page 26254 of that notice, we stated that
the range of distances for injury zones relative to the cSEL metric was
80-4,766 m. The correct range is 80-951 m; results are shown in Table
5.
Table 5--Estimated Auditory Injury Zones \1\
----------------------------------------------------------------------------------------------------------------
Hearing group Metric Spectrum ION TGS Western CGG
----------------------------------------------------------------------------------------------------------------
Low-frequency................... cSEL 757 951 380 80 757
peak 224 79 63 71 50
Mid-frequency................... cSEL 0 0 0 0 0
peak 63 22 18 20 14
High-frequency.................. cSEL 1 8 1 0 1
peak 1,585 562 447 501 355
Estimated near-field \2\........ ............. 417 233 142 80 141
----------------------------------------------------------------------------------------------------------------
\1\ Radial isopleth distances presented in meters.
\2\ See discussion of ``near-field'' below.
Based on our analysis of expected injury zones (Table 5),
accumulation of energy is considered to be the predominant source of
potential auditory injury for low-frequency cetaceans in all cases,
while instantaneous exposure to peak pressure received levels is
considered to be the predominant source of potential injury for both
mid- and high-frequency cetaceans in all cases. Please note that
discussion in this section and estimates of take by Level A harassment
provided in Table 6 for Spectrum relate to Spectrum's original survey
plan. Please see ``Spectrum Survey Plan Modification'' for additional
discussion of Level A harassment reflecting Spectrum's modified survey
plan.
Mid-Frequency Cetaceans--For all mid-frequency cetaceans, following
re-evaluation of the available scientific literature regarding the
auditory sensitivity of mid-frequency cetaceans and the properties of
airgun array sound fields, we do not expect any reasonable potential
for Level A harassment to occur. For these species, the only potential
injury zones (for all applicants) would be based on the peak pressure
metric (Table 5). However, the estimated zone sizes for the 230 dB peak
threshold for mid-frequency cetaceans range from only 14 m to 63 m.
While in a theoretical modeling scenario it is possible for animats to
engage with such small assumed zones around a notional point source
and, subsequently, for these interactions to scale to predictions of
real-world exposures given a sufficient number of predicted 24-hr
survey days in confluence with sufficiently high predicted real-world
animal densities--i.e., the modeling process that resulted in the
predicted exposure estimates for mid-frequency cetaceans in BOEM's
PEIS--this is not a realistic outcome. The source level of the array is
a theoretical definition assuming a point source and measurement in the
far-field of the source (MacGillivray, 2006). As described by Caldwell
and Dragoset (2000), an array is not a point source, but one that spans
a small area. In the far-field, individual elements in arrays will
effectively work as one source because individual pressure peaks will
have coalesced into one relatively broad pulse. The array can then be
considered a ``point source.'' For distances within the near-field,
i.e., approximately 2-3 times the array dimensions, pressure peaks from
individual elements do not arrive simultaneously because the
observation point is not equidistant from each element. The effect is
destructive interference of the outputs of each element, so that peak
pressures in the near-field will be significantly lower than the output
of the largest individual element. Here, the 230 dB peak isopleth
distances would in all cases be expected to be within the near-field of
the arrays where the definition of source level breaks down. Therefore,
actual locations within these distances (i.e., 14-63 m) of the array
center where the sound level exceeds 230 dB peak SPL would not
necessarily exist. In general, Caldwell and Dragoset (2000) suggest
that the near-field for airgun arrays is considered to extend out to
approximately 250 m.
In order to provide quantitative support for this theoretical
argument, we calculated expected maximum distances at which the near-
field would transition to the far-field (Table 5). For a specific array
one can estimate the distance at which the near-field transitions to
the far-field by:
[GRAPHIC] [TIFF OMITTED] TN07DE18.003
with the condition that D >> [lambda], and where D is the distance, L
is the longest dimension of the array, and [lambda] is the wavelength
of the signal (Lurton, 2002). Given that [lambda] can be defined by:
[GRAPHIC] [TIFF OMITTED] TN07DE18.004
where f is the frequency of the sound signal and v is the speed of the
sound in the medium of interest, one can rewrite the equation for D as:
[GRAPHIC] [TIFF OMITTED] TN07DE18.005
and calculate D directly given a particular frequency and known speed
of sound (here assumed to be 1,500
[[Page 63338]]
meters per second in water, although this varies with environmental
conditions).
To determine the closest distance to the arrays at which the source
level predictions in Table 1 are valid (i.e., maximum extent of the
near-field), we calculated D based on an assumed frequency of 1 kHz. A
frequency of 1 kHz is commonly used in near-field/far-field
calculations for airgun arrays (Zykov and Carr, 2014; MacGillivray,
2006; NSF and USGS, 2011), and based on representative airgun spectrum
data and field measurements of an airgun array used on the R/V Marcus
G. Langseth, nearly all (greater than 95 percent) of the energy from
airgun arrays is below 1 kHz (Tolstoy et al., 2009). Thus, using 1 kHz
as the upper cut-off for calculating the maximum extent of the near-
field should reasonably represent the near-field extent in field
conditions.
If the largest distance to the peak sound pressure level threshold
was equal to or less than the longest dimension of the array (i.e.,
under the array), or within the near-field, then received levels that
meet or exceed the threshold in most cases are not expected to occur.
This is because within the near-field and within the dimensions of the
array, the source levels specified in Table 1 are overestimated and not
applicable. In fact, until one reaches a distance of approximately
three or four times the near-field distance the average intensity of
sound at any given distance from the array is still less than that
based on calculations that assume a directional point source (Lurton,
2002). For example, an airgun array used on the R/V Marcus G. Langseth
has an approximate diagonal of 29 m, resulting in a near-field distance
of 140 m at 1 kHz (NSF and USGS, 2011). Field measurements of this
array indicate that the source behaves like multiple discrete sources,
rather than a directional point source, beginning at approximately 400
m (deep site) to 1 km (shallow site) from the center of the array
(Tolstoy et al., 2009), distances that are actually greater than four
times the calculated 140-m near-field distance. Within these distances,
the recorded received levels were always lower than would be predicted
based on calculations that assume a directional point source, and
increasingly so as one moves closer towards the array (Tolstoy et al.,
2009). Given this, relying on the calculated distances (Table 5) as the
distances at which we expect to be in the near-field is a conservative
approach since even beyond this distance the acoustic modeling still
overestimates the actual received level.
Within the near-field, in order to explicitly evaluate the
likelihood of exceeding any particular acoustic threshold, one would
need to consider the exact position of the animal, its relationship to
individual array elements, and how the individual acoustic sources
propagate and their acoustic fields interact. Given that within the
near-field and dimensions of the array source levels would be below
those in Table 1, we believe exceedance of the peak pressure threshold
would only be possible under highly unlikely circumstances.
Therefore, we expect the potential for Level A harassment of mid-
frequency cetaceans to be de minimis, even before the likely moderating
effects of aversion and/or other compensatory behaviors (e.g.,
Nachtigall et al., 2018) are considered. We do not believe that Level A
harassment is a likely outcome for any mid-frequency cetacean and do
not authorize any Level A harassment for these species.
Low-Frequency Cetaceans--For low-frequency cetaceans, we previously
adjusted the BOEM PEIS estimates of potential Level A harassment to
account for NMFS's technical acoustic guidance, as described in our
Notice of Proposed IHAs. This process resulted in few estimated Level A
harassment exposures for low-frequency cetaceans, i.e., 2-22 such
exposures for humpback whales and 0-1 such exposures for minke whales,
depending on array specifics, and zero exposures for right whales and
fin whales (see Table 11 in our Notice of Proposed IHAs). The potential
injury zones are relatively large for low-frequency cetaceans (up to
951 m; Table 5); therefore, we expect that some Level A harassment may
occur for the most commonly occurring low-frequency cetacean species
(i.e., humpback, fin, and minke whales). However, we also note that
injury on the basis of accumulation of energy is not a straightforward
consideration of calculated zone size, as is consideration of injury on
the basis of instantaneous peak pressure exposure. For example,
observation of a whale at the distance calculated as being the ``injury
zone'' using the cSEL criterion does not necessarily mean that the
animal has in fact incurred auditory injury. Rather, the animal would
have to be at the calculated distance (or closer) as the mobile source
approaches, passes, and recedes from the exposed animal, being exposed
to and accumulating energy from airgun pulses the entire time, as is
implied by the name of the ``safe distance'' methodology by which such
zone distances are calculated.
Therefore, while we do believe that some limited Level A harassment
of low-frequency cetaceans is likely unavoidable, despite the required
mitigation measures (including ramp-up, shutdown upon detection within
a 500-m exclusion zone for most mysticetes and shutdown upon detection
of North Atlantic right whales within an expanded 1.5-km exclusion
zone; see ``Mitigation''), we do not believe that the process followed
in estimating potential Level A harassment in our Notice of Proposed
IHAs is the most appropriate method. Further, upon re-evaluation of the
results of that process, we do not have confidence in those results,
which suggest that Level A harassment is likely for humpback whales but
not for fin whales. Upon reconsideration of the available information,
we note that the original information from BOEM's PEIS includes
prediction of zero incidents of Level A harassment for fin whales while
predicting non-zero results for all other mysticete species (see Table
E-4 in BOEM (2014a))--a puzzling result that underlies the lack of
predicted Level A harassment for fin whales in our Notice of Proposed
IHAs. Therefore, we apply a simplified approach intended to acknowledge
that there would likely be some minimal, yet difficult to accurately
quantify, Level A harassment of certain mysticete species. As a result
of the planned mitigation, including a seasonal restriction (or
alternate methods of equivalent impact avoidance) and an expanded right
whale exclusion zone of 1.5 km (intended to practicably avoid or
minimize interaction with North Atlantic right whales; see
``Mitigation''), we do not expect any reasonable potential for Level A
harassment of North Atlantic right whales (consistent with the
predictions of our original analysis). Any likely potential for the
occurrence of Level A harassment is further minimized by likely
aversion. For example, Ellison et al. (2016) demonstrated that animal
movement models where no aversion probability was used overestimated
the potential for high levels of exposure required for PTS by about
five times.
In order to account for the minimal likelihood of Level A
harassment occurring for low-frequency cetaceans, we assume that in
most cases during the course of conducting the survey at least one
group of each species could incur auditory injury for all applicants
other than Western. (As shown in Table 5, the calculated injury zone
for Western is only 80 m. It is extremely unlikely that injury could
occur given such a small
[[Page 63339]]
calculated zone, especially in context of a required 500-m exclusion
zone.) We acknowledge that application of group size to estimation of
take is more appropriate for take resulting from instantaneous exposure
than it is for take resulting from the accumulation of energy, as any
given group may disperse to some degree in a way that could lead to
differing accumulation among individuals of the group. However, given
the low likelihood of take by Level A harassment, small group sizes
typical of mysticetes, and the likelihood that these individuals will
remain within close distance of one another during the exposure, we
believe that use of group size is appropriate in this context.
For applicants other than Western, we consider both the size of the
calculated potential injury zone and the total amount of planned survey
effort. Spectrum, CGG, and ION have larger calculated potential injury
zones, i.e., larger than the required 500-m exclusion zone (Table 5).
However, ION has significantly less total survey effort (approximately
half of what is planned by Spectrum and CGG; Table 1). TGS has a
significantly smaller calculated injury zone, i.e., smaller than the
required 500-m exclusion zone. However, at 380 m, the zone is
sufficiently large that a whale could potentially occur within the zone
without being observed in time to implement shutdown, and TGS's planned
survey effort is substantially larger (approximately twice as large as
that planned by Spectrum and CGG). Therefore, TGS' lower likelihood of
causing injury is offset to some degree by their substantially greater
survey effort. Finally, on the basis of expected taking by Level B
harassment (Table 6), we see that the location and timing of CGG's
planned survey effort results in significantly less potential
interaction with humpback whales than for Spectrum and TGS.
In summary, we conclude there is sufficiently reasonable potential
for Level A harassment (even considering the likely effects of
aversion) that it is appropriate to authorize take by Level A
harassment for a minimum of one average size group of each relevant
species (i.e., humpback, minke, and fin whales) for Spectrum, TGS, ION,
and CGG. For Spectrum, in consideration of the calculated injury zone
and level of planned effort, we increase this to two groups of each
relevant species. For TGS, in consideration of the level of planned
survey effort and despite the smaller calculated injury zone, we also
increase this to two groups of each relevant species. For CGG, in
consideration of the calculated injury zone and level of planned
effort, we increase this to two groups for minke whales and fin whales
only, given the lower potential for interaction with humpback whales.
For ION, given the lower level of planned survey effort, we maintain
the take authorization at one group of each relevant species. As a
point of reference, we note that BOEM's PEIS analysis of potential
takes by Level A harassment estimated that no more than 5.9 humpback
whales could experience auditory injury in any given year for all
surveys combined, despite a greater amount of assumed activity.
Estimates were much less for all other species (see Table E-4 of BOEM
(2014a)). As noted above, please see ``Spectrum Survey Plan
Modification'' for additional discussion of Level A harassment
reflecting Spectrum's modified survey plan, including Table 17,
providing revised (and authorized) levels of take by Level A harassment
for Spectrum.
Average group size was determined by considering observational data
from AMAPPS survey effort (e.g., NMFS, 2010a, 2011, 2012, 2013a, 2014,
2015a). Average group sizes were as follows: Fin whale, 1.3 whales;
humpback whale, 1.4 whales; minke whale, 1.2 whales. Therefore, we
assume an average group size of two whales for each species. These take
authorizations, which are subtracted from the estimates for take by
Level B harassment to avoid double-counting, are shown in Table 6.
High-Frequency Cetaceans--For high-frequency cetaceans (i.e., Kogia
spp. and harbor porpoise), injury zones are based on instantaneous
exposure to peak pressure and are larger than the expected near-field
in all cases (i.e., 355-1,585 m). Therefore, we assume that Level A
harassment is likely for some individuals of these species. In order to
avoid consistency issues that may result when estimates of Level A
harassment are based off of the results of a separate analysis that was
founded in part on use of different density inputs, as was the case for
the estimates of Level A harassment described in our Notice of Proposed
IHAs, we simplified the analysis through use of the existing estimates
of Level B harassment for each applicant. Under the assumption that
some of these estimated exposures would in fact result in Level A
harassment versus Level B harassment, we used applicant-specific
calculated Level A and Level B harassment zones to generate estimates
of the portion of estimated Level B harassment incidents that would be
expected to be Level A harassment instead. For example, radial isopleth
distances for Spectrum's calculated harassment zones are 1,585 m for
Level A harassment and a mean of 9,775 m for Level B harassment, which
we use to calculate relative area. On this basis, we assume that
approximately 2.6 percent of estimated Level B harassment incidents
would potentially be Level A harassment instead (for Spectrum). These
final estimates, shown in Table 6, were then subtracted from the total
take by Level B harassment. As noted for low-frequency cetaceans, we
recognize that the effects of aversion would likely reduce these
already low levels of Level A harassment.
We recognize that the Level A exposure estimates provided here are
a rough approximation of actual exposures; however, our intention is to
use the information available to us, in reflection of available science
regarding the potential for auditory injury, to acknowledge the
potential for such outcomes in a way that is a reasonable
approximation. Our revised analysis of potential Level A harassment, as
reflected in Table 6, accomplishes this goal. As described in our
Notice of Proposed IHAs, we note here that four of the five applicant
companies (excepting Spectrum) declined to request authorization of
take by Level A harassment. These four applicants claim, in summary,
that injurious exposures will not occur largely due to the
effectiveness of planned mitigation. While we agree that Level A
harassment is unlikely for mid-frequency cetaceans, and that only
limited injurious exposure is likely for low-frequency cetaceans, we do
not find this assertion persuasive in all cases. Therefore, we are
authorizing limited take by Level A harassment, as displayed in Table
6.
Rare Species
Certain species potentially present in the survey areas are
expected to be encountered only extremely rarely, if at all. Although
Roberts et al. (2016) provide density models for these species (with
the exception of the pygmy killer whale), due to the small numbers of
sightings that underlie these models' predictions we believe it
appropriate to account for the small likelihood that these species
would be encountered by assuming that these species might be
encountered once by a given survey, and that Level A harassment would
not occur for these species. With the exception of the northern
bottlenose whale, none of these species should be considered cryptic
(i.e., difficult to observe when present) versus rare (i.e., not likely
to be present). Average group size was determined by considering known
sightings in the western North
[[Page 63340]]
Atlantic (CETAP, 1982; Hansen et al, 1994; NMFS, 2010a, 2011, 2012,
2013a, 2014, 2015a; Waring et al., 2007, 2015). We provided discussion
for each of these species in our Notice of Proposed IHAs, and do not
repeat the discussion here. For each of these species--sei, Bryde's,
and blue whales; the northern bottlenose whale; killer whale, false
killer whale, pygmy killer whale, and melon-headed whale; and spinner,
Fraser's, and Atlantic white-sided dolphins--we authorize take
equivalent to one group of each species per applicant (Table 6).
Table 6 provides the authorized numbers of take by Level A and
Level B harassment for each applicant. The numbers of authorized take
reflect the expected exposure numbers provided in Table 10 of our
Notice of Proposed IHAs, as derived by various methods described above,
and additionally include take numbers for rare species that reflect the
approach described above for average group size. In summary, the
exposure estimates provided in Table 10 of our Notice of Proposed IHAs
have been changed in reflection of the following: (1) Revised exposure
estimates for North Atlantic right whales using Roberts et al. (2017);
(2) removed exposure estimates specific to use of the disallowed
mitigation source as necessary for certain species (TGS only); (3)
removed estimated take avoided as a result of implementation of planned
time-area restrictions; and (4) revised analysis of potential Level A
harassment.
As described previously, for most species these estimated exposure
levels apply to a generic western North Atlantic stock defined by NMFS
for management purposes. For the humpback and sei whale, any takes are
assumed to occur to individuals of the species occurring in the
specific geographic region (which may or may not be individuals from
the Gulf of Maine and Nova Scotia stocks, respectively). For bottlenose
dolphins, NMFS defines an offshore stock and multiple coastal stocks of
dolphins, and we are not able to quantitatively determine the extent to
which the estimated exposures may accrue to the oceanic versus various
coastal stocks. However, because of the spatial distribution of planned
survey effort and our prescribed mitigation, we assume that almost all
incidents of take for bottlenose dolphins would accrue to the offshore
stock.
Table 6--Numbers of Potential Instances of Incidental Take Authorized
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Spectrum \1\ TGS ION Western CGG
Common name ---------------------------------------------------------------------------------------------------------------------------------
Level A Level B Level A Level B Level A Level B Level A Level B Level A Level B
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
North Atlantic right whale.................................... 0 6 0 9 0 2 0 4 0 2
Humpback whale................................................ 4 41 4 56 2 5 0 49 2 5
Minke whale................................................... 4 419 4 208 2 10 0 100 4 124
Bryde's whale................................................. 0 2 0 2 0 2 0 2 0 2
Sei whale..................................................... 0 2 0 2 0 2 0 2 0 2
Fin whale..................................................... 4 333 4 1,140 2 3 0 537 4 45
Blue whale.................................................... 0 1 0 1 0 1 0 1 0 1
Sperm whale................................................... 0 1,077 0 3,579 0 16 0 1,941 0 1,304
Kogia spp..................................................... 5 200 5 1,216 \2\ 2 28 3 569 \2\ 2 238
Beaked whales................................................. 0 3,357 0 12,072 0 490 0 4,960 0 3,511
Northern bottlenose whale..................................... 0 4 0 4 0 4 0 4 0 4
Rough-toothed dolphin......................................... 0 201 0 261 0 \1\ 14 0 123 0 177
Common bottlenose dolphin..................................... 0 37,562 0 40,595 0 2,599 0 23,600 0 9,063
Clymene dolphin............................................... 0 6,459 0 821 0 252 0 391 0 6,382
Atlantic spotted dolphin...................................... 0 16,926 0 41,222 0 568 0 18,724 0 6,596
Pantropical spotted dolphin................................... 0 1,632 0 1,470 0 78 0 690 0 1,566
Spinner dolphin............................................... 0 91 0 91 0 91 0 91 0 91
Striped dolphin............................................... 0 8,022 0 23,418 0 162 0 8,845 0 6,328
Common dolphin................................................ 0 11,087 0 52,728 0 372 0 20,683 0 6,026
Fraser's dolphin.............................................. 0 204 0 204 0 204 0 204 0 204
Atlantic white-sided dolphin.................................. 0 48 0 48 0 48 0 48 0 48
Risso's dolphin............................................... 0 755 0 3,241 0 90 0 1,608 0 809
Melon-headed whale............................................ 0 50 0 50 0 50 0 50 0 50
Pygmy killer whale............................................ 0 6 0 6 0 6 0 6 0 6
False killer whale............................................ 0 28 0 28 0 28 0 28 0 28
Killer whale.................................................. 0 7 0 7 0 7 0 7 0 7
Pilot whales.................................................. 0 2,765 0 8,902 0 199 0 4,682 0 1,964
Harbor porpoise............................................... 16 611 \2\ 3 322 \2\ 3 18 \2\ 3 152 \2\ 3 27
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Take numbers provided for Spectrum reflect Spectrum's original survey plan and are retained here in reference to the negligible impact and small numbers analyses provided later in this
document for Spectrum. For revised (and authorized) take numbers for Spectrum reflecting their modified survey plan, please see ``Spectrum Survey Plan Modification.''
\2\ Exposure estimate increased to account for average group size observed during AMAPPS survey effort. For ION, estimated Level A harassment of Kogia spp. and harbor porpoise was zero and,
for CGG, estimated Level A harassment of harbor porpoise was zero. We assume as a precaution that one group (as estimated from AMAPPS data) may incur Level A harassment.
[[Page 63341]]
Mitigation
Under section 101(a)(5)(D) of the MMPA, NMFS must set forth the
``permissible methods of taking pursuant to such activity, and other
means of effecting the least practicable impact on such species or
stock and its habitat, paying particular attention to rookeries, mating
grounds, and areas of similar significance, and on the availability of
such species or stock for taking for certain subsistence uses.'' (While
section 101(a)(5)(D) refers to ``least practicable impact,'' we
hereafter use the term ``least practicable adverse impact,'' the term
as it appears in section 101(a)(5)(A). Given the provision in which the
language appears, and its similarity to the parallel provision in
section 101(a)(5)(A), we believe that ``least practicable impact'' in
section 101(a)(5)(D) similarly is referring to the requirement to
prescribe the means of effecting the least practicable adverse impact,
and we interpret the term in that manner.) Consideration of the
availability of marine mammal species or stocks for taking for
subsistence uses pertains only to Alaska, and is therefore not relevant
here. NMFS does not have a regulatory definition for ``least
practicable adverse impact.''
In Conservation Council for Hawaii v. National Marine Fisheries
Service, 97 F. Supp.3d 1210, 1229 (D. Haw. 2015), the Court stated that
NMFS ``appear[s] to think [it] satisf[ies] the statutory `least
practicable adverse impact' requirement with a `negligible impact'
finding.'' More recently, expressing similar concerns in a challenge to
an incidental take rule for U.S. Navy Operation of Surveillance Towed
Array Sensor System Low Frequency Active Sonar (SURTASS LFA) (77 FR
50290), the Ninth Circuit Court of Appeals in Natural Resources Defense
Council (NRDC) v. Pritzker, 828 F.3d 1125, 1134 (9th Cir. 2016),
stated, ``[c]ompliance with the `negligible impact' requirement does
not mean there [is] compliance with the `least practicable adverse
impact' standard.'' As the Ninth Circuit noted in its opinion, however,
the Court was interpreting the statute without the benefit of NMFS's
formal interpretation. We state here explicitly that NMFS is in full
agreement that the ``negligible impact'' and ``least practicable
adverse impact'' requirements are distinct, even though both statutory
standards refer to species and stocks. With that in mind, we provide
further explanation of our interpretation of least practicable adverse
impact, and explain what distinguishes it from the negligible impact
standard. This discussion is consistent with, and expands upon,
previous rules we have issued (such as the Navy Gulf of Alaska rule (82
FR 19530; April 27, 2017)).
Before NMFS can issue an incidental take authorization under
sections 101(a)(5)(A) or (D) of the MMPA, it must make a finding that
the taking will have a ``negligible impact'' on the affected ``species
or stocks'' of marine mammals. NMFS's and U.S. Fish and Wildlife
Service's implementing regulations for section 101(a)(5) both define
``negligible impact'' as an impact resulting from the specified
activity that cannot be reasonably expected to, and is not reasonably
likely to, adversely affect the species or stock through effects on
annual rates of recruitment or survival (50 CFR 216.103 and 50 CFR
18.27(c)). Recruitment (i.e., reproduction) and survival rates are used
to determine population growth rates \1\ and, therefore are considered
in evaluating population level impacts.
---------------------------------------------------------------------------
\1\ A growth rate can be positive, negative, or flat.
---------------------------------------------------------------------------
Not every population-level impact violates the negligible impact
requirement. The negligible impact standard does not require a finding
that the anticipated take will have ``no effect'' on population numbers
or growth rates. The statutory standard does not require that the same
recovery rate be maintained, rather that no significant effect on
annual rates of recruitment or survival occurs. The key factor is the
significance of the level of impact on rates of recruitment or
survival. See 54 FR 40338, 40341-42 (September 29, 1989).
While some level of impact on population numbers or growth rates of
a species or stock may occur and still satisfy the negligible impact
requirement--even without consideration of mitigation--the least
practicable adverse impact provision separately requires NMFS to
prescribe means of effecting the least practicable adverse impact on
such species or stock and its habitat, paying particular attention to
rookeries, mating grounds, and areas of similar significance. 50 CFR
216.102(b). These are typically identified as mitigation measures.\2\
---------------------------------------------------------------------------
\2\ For purposes of this discussion we omit reference to the
language in the standard for least practicable adverse impact that
says we also must mitigate for subsistence impacts because they are
not at issue in these actions.
---------------------------------------------------------------------------
The negligible impact and least practicable adverse impact
standards in the MMPA both call for evaluation at the level of the
``species or stock.'' The MMPA does not define the term ``species.''
However, Merriam-Webster Dictionary defines ``species'' to include
``related organisms or populations potentially capable of
interbreeding.'' See www.merriam-webster.com/dictionary/species
(emphasis added). The MMPA defines ``stock'' as a group of marine
mammals of the same species or smaller taxa in a common spatial
arrangement that interbreed when mature. 16 U.S.C. 1362(11). The
definition of ``population'' is ``a group of interbreeding organisms
that represents the level of organization at which speciation begins.''
www.merriam-webster.com/dictionary/population. The definition of
``population'' is strikingly similar to the MMPA's definition of
``stock,'' with both involving groups of individuals that belong to the
same species and located in a manner that allows for interbreeding. In
fact, the term ``stock'' in the MMPA is interchangeable with the
statutory term ``population stock.'' 16 U.S.C. 1362(11). Thus, the MMPA
terms ``species'' and ``stock'' both relate to populations, and it is
therefore appropriate to view both the negligible impact standard and
the least practicable adverse impact standard, both of which call for
evaluation at the level of the species or stock, as having a
population-level focus.
This interpretation is consistent with Congress's statutory
findings for enacting the MMPA, nearly all of which are most applicable
at the species or stock (i.e., population) level. See 16 U.S.C. 1361
(finding that it is species and population stocks that are or may be in
danger of extinction or depletion; that it is species and population
stocks that should not diminish beyond being significant functioning
elements of their ecosystems; and that it is species and population
stocks that should not be permitted to diminish below their optimum
sustainable population level). Annual rates of recruitment (i.e.,
reproduction) and survival are the key biological metrics used in the
evaluation of population-level impacts, and accordingly these same
metrics are also used in the evaluation of population level impacts for
the least practicable adverse impact standard.
Recognizing this common focus of the least practicable adverse
impact and negligible impact provisions on the ``species or stock''
does not mean we conflate the two standards; despite some common
statutory language, we recognize the two provisions are different and
have different functions. First, a negligible impact finding is
required before NMFS can issue an incidental take authorization.
Although it is acceptable to use the mitigation measures to reach a
negligible impact finding (see 50 CFR 216.104(c)), no amount of
mitigation can enable NMFS
[[Page 63342]]
to issue an incidental take authorization for an activity that still
would not meet the negligible impact standard. Moreover, even where
NMFS can reach a negligible impact finding--which we emphasize does
allow for the possibility of some ``negligible'' population-level
impact--the agency must still prescribe measures that will effect the
least practicable amount of adverse impact upon the affected species or
stock.
Section 101(a)(5)(D)(ii)(I) (like section 101(a)(5)(A)(i)(II))
requires NMFS to issue, in conjunction with its authorization,
binding--and enforceable--restrictions setting forth how the activity
must be conducted, thus ensuring the activity has the ``least
practicable adverse impact'' on the affected species or stocks. In
situations where mitigation is specifically needed to reach a
negligible impact determination, section 101(a)(5)(D)(ii)(I) also
provides a mechanism for ensuring compliance with the ``negligible
impact'' requirement. Finally, we reiterate that the least practicable
adverse impact standard also requires consideration of measures for
marine mammal habitat, with particular attention to rookeries, mating
grounds, and other areas of similar significance, and for subsistence
impacts; whereas the negligible impact standard is concerned solely
with conclusions about the impact of an activity on annual rates of
recruitment and survival.\3\
---------------------------------------------------------------------------
\3\ Mitigation may also be appropriate to ensure compliance with
the ``small numbers'' language in MMPA sections 101(a)(5)(A) and
(D).
---------------------------------------------------------------------------
In NRDC v. Pritzker, the Court stated, ``[t]he statute is properly
read to mean that even if population levels are not threatened
significantly, still the agency must adopt mitigation measures aimed at
protecting marine mammals to the greatest extent practicable in light
of military readiness needs.'' Id. at 1134 (emphases added). This
statement is consistent with our understanding stated above that even
when the effects of an action satisfy the negligible impact standard
(i.e., in the Court's words, ``population levels are not threatened
significantly''), still the agency must prescribe mitigation under the
least practicable adverse impact standard. However, as the statute
indicates, the focus of both standards is ultimately the impact on the
affected ``species or stock,'' and not solely focused on or directed at
the impact on individual marine mammals.
We have carefully reviewed and considered the Ninth Circuit's
opinion in NRDC v. Pritzker in its entirety. While the Court's
reference to ``marine mammals'' rather than ``marine mammal species or
stocks'' in the italicized language above might be construed as a
holding that the least practicable adverse impact standard applies at
the individual ``marine mammal'' level, i.e., that NMFS must require
mitigation to minimize impacts to each individual marine mammal unless
impracticable, we believe such an interpretation reflects an incomplete
appreciation of the Court's holding. In our view, the opinion as a
whole turned on the Court's determination that NMFS had not given
separate and independent meaning to the least practicable adverse
impact standard apart from the negligible impact standard, and further,
that the Court's use of the term ``marine mammals'' was not addressing
the question of whether the standard applies to individual animals as
opposed to the species or stock as a whole. We recognize that while
consideration of mitigation can play a role in a negligible impact
determination, consideration of mitigation measures extends beyond that
analysis. In evaluating what mitigation measures are appropriate, NMFS
considers the potential impacts of the specified activity, the
availability of measures to minimize those potential impacts, and the
practicability of implementing those measures, as we describe below.
Given the NRDC v. Pritzker decision, we discuss here how we
determine whether a measure or set of measures meets the ``least
practicable adverse impact'' standard. Our separate analysis of whether
the take anticipated to result from applicants' activities satisfies
the ``negligible impact'' standard appears in the section ``Negligible
Impact Analyses and Determinations'' below.
Our evaluation of potential mitigation measures includes
consideration of two primary factors:
(1) The manner in which, and the degree to which, implementation of
the potential measure(s) is expected to reduce adverse impacts to
marine mammal species or stocks, their habitat, and their availability
for subsistence uses (when relevant). This analysis considers such
things as the nature of the potential adverse impact (such as
likelihood, scope, and range), the likelihood that the measure will be
effective if implemented, and the likelihood of successful
implementation.
(2) The practicability of the measure for applicant implementation.
Practicability of implementation may consider such things as cost,
impact on operations, personnel safety, and practicality of
implementation.
While the language of the least practicable adverse impact standard
calls for minimizing impacts to affected species or stocks, we
recognize that the reduction of impacts to those species or stocks
accrues through the application of mitigation measures that limit
impacts to individual animals. Accordingly, NMFS's analysis focuses on
measures designed to avoid or minimize impacts on marine mammals from
activities that are likely to increase the probability or severity of
population-level effects.
While complete information on impacts to species or stocks from a
specified activity is not available for every activity type, and
additional information would help NMFS better understand how specific
disturbance events affect the fitness of individuals of certain
species, there have been significant improvements in understanding the
process by which disturbance effects are translated to the population.
With recent scientific advancements (both marine mammal energetic
research and the development of energetic frameworks), the relative
likelihood or degree of impacts on species or stocks may typically be
predicted given a detailed understanding of the activity, the
environment, and the affected species or stocks. This same information
is used in the development of mitigation measures and helps us
understand how mitigation measures contribute to lessening effects to
species or stocks. We also acknowledge that there is always the
potential that new information, or a new recommendation that we had not
previously considered, becomes available and necessitates re-evaluation
of mitigation measures (which may be addressed through adaptive
management) to see if further reductions of population impacts are
possible and practicable.
In the evaluation of specific measures, the details of the
specified activity will necessarily inform each of the two primary
factors discussed above (expected reduction of impacts and
practicability), and will be carefully considered to determine the
types of mitigation that are appropriate under the least practicable
adverse impact standard. Analysis of how a potential mitigation measure
may reduce adverse impacts on a marine mammal stock or species and
practicability of implementation are not issues that can be
meaningfully evaluated through a yes/no lens. The manner in which, and
the degree to which, implementation of a measure is expected to reduce
impacts, as well as its practicability, can vary widely. For example, a
time-area
[[Page 63343]]
restriction could be of very high value for decreasing population-level
impacts (e.g., avoiding disturbance of feeding females in an area of
established biological importance) or it could be of lower value (e.g.,
decreased disturbance in an area of high productivity but of less
firmly established biological importance). Regarding practicability, a
measure might involve operational restrictions that completely impede
the operator's ability to acquire necessary data (higher impact), or it
could mean additional incremental delays that increase operational
costs but still allow the activity to be conducted (lower impact). A
responsible evaluation of ``least practicable adverse impact'' will
consider the factors along these realistic scales. Expected effects of
the activity and of the mitigation as well as status of the stock all
weigh into these considerations. Accordingly, the greater the
likelihood that a measure will contribute to reducing the probability
or severity of adverse impacts to the species or stock or their
habitat, the greater the weight that measure is given when considered
in combination with practicability to determine the appropriateness of
the mitigation measure, and vice versa. We discuss consideration of
these factors in greater detail below.
1. Reduction of Adverse Impacts to Marine Mammal Species or Stocks and
Their Habitat 4
---------------------------------------------------------------------------
\4\ We recognize the least practicable adverse impact standard
requires consideration of measures that will address minimizing
impacts on the availability of the species or stocks for subsistence
uses where relevant. Because subsistence uses are not implicated for
this action we do not discuss them. However, a similar framework
would apply for evaluating those measures, taking into account the
MMPA's directive that we make a finding of no unmitigable adverse
impact on the availability of the species or stocks for taking for
subsistence, and the relevant implementing regulations.
---------------------------------------------------------------------------
The emphasis given to a measure's ability to reduce the impacts on
a species or stock considers the degree, likelihood, and context of the
anticipated reduction of impacts to individuals as well as the status
of the species or stock.
The ultimate impact on any individual from a disturbance event
(which informs the likelihood of adverse species- or stock-level
effects) is dependent on the circumstances and associated contextual
factors, such as duration of exposure to stressors. Though any required
mitigation needs to be evaluated in the context of the specific
activity and the species or stocks affected, measures with the
following types of goals are expected to reduce the likelihood or
severity of adverse species- or stock-level impacts: Avoiding or
minimizing injury or mortality; limiting interruption of known feeding,
breeding, mother/calf, or resting behaviors; minimizing the abandonment
of important habitat (temporally and spatially); minimizing the number
of individuals subjected to these types of disruptions; and limiting
degradation of habitat. Mitigating these types of effects is intended
to reduce the likelihood that the activity will result in energetic or
other types of impacts that are more likely to result in reduced
reproductive success or survivorship. It is also important to consider
the degree of impacts that are expected in the absence of mitigation in
order to assess the added value of any potential measures. Finally,
because the least practicable adverse impact standard gives NMFS the
discretion to weigh a variety of factors when determining what should
be included as appropriate mitigation measures and because the focus is
on reducing impacts at the species or stock level, it does not compel
mitigation for every kind of individual take, even when practicable for
implementation by the applicant.
The status of the species or stock is also relevant in evaluating
the appropriateness of potential mitigation measures in the context of
least practicable adverse impact. The following are examples of factors
that may (either alone, or in combination) result in greater emphasis
on the importance of a mitigation measure in reducing impacts on a
species or stock: The stock is known to be decreasing or status is
unknown, but believed to be declining; the known annual mortality (from
any source) is approaching or exceeding the PBR level; the affected
species or stock is a small, resident population; or the stock is
involved in a UME or has other known vulnerabilities.
Habitat mitigation, particularly as it relates to rookeries, mating
grounds, and areas of similar significance, is also relevant to
achieving the standard and can include measures such as reducing
impacts of the activity on known prey utilized in the activity area or
reducing impacts on physical habitat. As with species- or stock-related
mitigation, the emphasis given to a measure's ability to reduce impacts
on a species or stock's habitat considers the degree, likelihood, and
context of the anticipated reduction of impacts to habitat. Because
habitat value is informed by marine mammal presence and use, in some
cases there may be overlap in measures for the species or stock and for
use of habitat.
We consider available information indicating the likelihood of any
measure to accomplish its objective. If evidence shows that a measure
has not typically been effective or successful, then either that
measure should be modified or the potential value of the measure to
reduce effects is lowered.
2. Practicability
Factors considered may include those such as cost, impact on
operations, personnel safety, and practicality of implementation.
In carrying out the MMPA's mandate for these five IHAs, we apply
the previously described context-specific balance between the manner in
which and the degree to which measures are expected to reduce impacts
to the affected species or stocks and their habitat and practicability
for the applicant. The effects of concern (i.e., those with the
potential to adversely impact species or stocks and their habitat),
addressed previously in the ``Potential Effects of the Specified
Activity on Marine Mammals and Their Habitat'' section, include
auditory injury, severe behavioral reactions, disruptions of critical
behaviors, and to a lesser degree, masking and impacts on acoustic
habitat (see discussion of this concept in the ``Anticipated Effects on
Marine Mammal Habitat'' section in the Notice of Proposed IHAs). Here,
we focus on measures with proven or reasonably presumed ability to
avoid or reduce the intensity of acute exposures that have potential to
result in these anticipated effects with an understanding of the
drawbacks or costs of these requirements, as well as time-area
restrictions that would avoid or reduce both acute and chronic impacts.
To the extent of the information available to us, we considered
practicability concerns, as well as potential undesired consequences of
the measures, e.g., extended periods using the acoustic source due to
the need to reshoot lines. We also recognize that instantaneous
protocols, such as shutdown requirements, are not capable of avoiding
all acute effects, and are not suitable for avoiding many cumulative or
chronic effects and do not provide targeted protection in areas of
greatest importance for marine mammals. Therefore, in addition to a
basic suite of seismic mitigation protocols, we also consider measures
that may or may not be appropriate for other activities (e.g., time-
area restrictions specific to the surveys discussed herein) but that
are warranted here given the spatial scope of these specified
activities, potential for population-level effects and/or high
magnitude of take for certain species in the absence of such mitigation
(see ``Negligible Impact Analyses and
[[Page 63344]]
Determinations''), and the information we have regarding habitat for
certain species.
In order to satisfy the MMPA's least practicable adverse impact
standard, we evaluated a suite of basic mitigation protocols that are
required regardless of the status of a stock. Additional or enhanced
protections are required for species whose stocks are in poor health
and/or are subject to some significant additional stressor that lessens
that stock's ability to weather the effects of the specified activities
without worsening its status. We reviewed the applicants' proposals,
the requirements specified in BOEM's PEIS, seismic mitigation protocols
required or recommended elsewhere (e.g., HESS, 1999; DOC, 2013; IBAMA,
2005; Kyhn et al., 2011; JNCC, 2017; DEWHA, 2008; BOEM, 2016a; DFO,
2008; GHFS, 2015; MMOA, 2015; Nowacek et al., 2013; Nowacek and
Southall, 2016), and the available scientific literature. We also
considered recommendations given in a number of review articles (e.g.,
Weir and Dolman, 2007; Compton et al., 2008; Parsons et al., 2009;
Wright and Cosentino, 2015; Stone, 2015b). Certain changes from the
mitigation measures described in our Notice of Proposed IHAs were made
on the basis of additional information and following review of public
comments. The required suite of mitigation measures differs in some
cases from the measures proposed by the applicants and/or those
specified by BOEM in their PEIS and Record of Decision (ROD) in order
to reflect what we believe to be the most appropriate suite of measures
to satisfy the requirements of the MMPA.
First, we summarize notable changes made to the mitigation
requirements as a result of review of public comments and then describe
mitigation prescribed in the issued IHAs. For additional detail
regarding mitigation considerations, including expected efficacy and/or
practicability, or descriptions of mitigation considered but not
required, please see our Notice of Proposed IHAs.
Here we provide a single description of required mitigation
measures, as we require the same measures of all applicants.
Changes From the Notice of Proposed IHAs
Here we summarize substantive changes to mitigation requirements
from our Notice of Proposed IHAs. All changes were made on the basis of
review of public comments received, including from applicants, and/or
review of new information.
Time-Area Restrictions
We spatially expanded the proposed time-area restriction
for North Atlantic right whales. Our proposed restriction area was
comprised of an area containing three distinct areas: (1) A 20-nmi
coastal strip throughout the specific geographic region; (2) designated
Seasonal Management Areas; and (3) designated critical habitat. This
combined area was then buffered by 10 km, resulting in an approximate
47-km standoff distance. We received numerous public comments
expressing concern regarding the adequacy of this measure and, more
generally, regarding the status of the North Atlantic right whale.
Also, since publication of the Notice of Proposed IHAs, the status of
this population has worsened, including declaration of an ongoing UME.
Given this, we considered newly available information (e.g., Roberts et
al., 2017; Davis et al., 2017) and re-evaluated the restriction. This
is described in more detail under ``Comments and Responses'' as well as
later in this section. Following this review, we expanded the
restriction to 80 km from shore, with the same 10-km buffer, for a
total 90-km restriction. As was proposed, the restriction would be in
effect from November through April.
However, in lieu of this requirement, applicants may alternatively
develop and submit a monitoring and mitigation plan for NMFS's approval
that would be sufficient to achieve comparable protection for North
Atlantic right whales. If approved, applicants would be required to
maintain a minimum coastal standoff distance of 47 km from November
through April while operating in adherence with the approved plan from
47 through 80 km offshore. (Note that the 80 km distance is assumed to
represent to a reasonable extent right whale occurrence on the
migratory pathway; therefore, under an approved plan the 10-km buffer
would not be relevant.)
We shifted the timing of the ``Hatteras and North'' time-
area restriction (Area #4 in Figure 4 and Table 7; described as Area #5
in our Notice of Proposed IHAs), developed primarily to benefit beaked
whales, sperm whales, and pilot whales, but also to provide seasonal
protection to a notable biodiversity hotspot. The timing of this
restriction, proposed as July through September (Roberts et al.,
2015n), is shifted to January through March on the basis of new
information (Stanistreet et al., 2018), as described in more detail
later in this section. The restriction area remains the same.
We eliminated the proposed (former) Area #1, which was
delineated in an effort to reduce likely acoustic exposures for the
species for three applicants only, as opposed to a more meaningful
reduction of impacts in important habitat and/or for species expected
to be more sensitive to disturbance from airgun noise. As was stated in
our Notice of Proposed IHAs, ``Although there are no relevant
considerations with regard to population context or specific stressors
that lead us to develop mitigation focused on Atlantic spotted dolphins
[ . . . ] we believe it appropriate to delineate a time-area
restriction for the sole purpose of reducing likely acoustic exposures
for the species [for three companies].'' We received comments on this
proposed restriction from several commenters who provided compelling
rationale to eliminate the measure. As was stated in our Notice of
Proposed IHAs, Atlantic spotted dolphins display a bifurcated
distribution, with a portion of the stock inhabiting the continental
shelf south of Cape Hatteras inside the 200-m isobath and a portion of
the stock off the shelf and north of the Gulf Stream (north of Cape
Hatteras). Our proposed restriction--located in the southern, on-shelf
portion of the range, which we believe to be more predictable habitat
for the species--was not likely to have the intended effect, as a
seasonal restriction would not necessarily reduce acoustic exposures
for a species that is not known to migrate in and out of the
restriction area, and because a relatively small portion of overall
survey effort was planned for this area. Implementation of this
restriction would also likely have meaningful practicability
implications for applicants with survey lines in the area, as they
would need to plan for both the seasonal restriction for spotted
dolphin (proposed as July through September) as well as the right whale
restriction, which overlaps the proposed spotted dolphin area and would
be in effect from November through April. Therefore, the proposal would
not likely provide commensurate benefit to the species to offset these
concerns.
Shutdown Requirements
In our Notice of Proposed IHAs, we proposed an exception
to the general shutdown requirements for certain species of dolphins in
certain circumstances. Specifically, we proposed that the exception to
the shutdown requirement would apply if the animals are traveling,
including approaching the vessel. Our rationale in proposing this
specific exception was to avoid the perceived subjective decision-
[[Page 63345]]
making associated with an exception based on a determination that
dolphins were approaching voluntarily, while still protecting dolphins
from disturbance of potentially important behaviors such as feeding or
socialization, as might be indicated by the presence of dolphins
engaged in behavior other than traveling (e.g., milling). Although the
``bow-riding'' dolphin exception was similarly criticized when
presented for public comment in BOEM's draft PEIS, we agree that our
proposal (i.e., based on ``traveling'' versus ``stationary'' dolphins
in relation to the vessel's movement) was unclear and that it would not
likely result in an improvement with regard to clarity of protected
species observer (PSO) decision-making. Therefore, this proposal was
properly considered impracticable, while not offering meaningfully
commensurate biological benefit. While we are careful to note that we
do not fully understand the reasons for and potential effects of
dolphin interaction with vessels, including working survey vessels, we
also understand that dolphins are unlikely to incur any degree of
threshold shift due to their relative lack of sensitivity to the
frequency content in an airgun signal (as well as because of potential
coping mechanisms). We also recognize that, although dolphins do in
fact react to airgun noise in ways that may be considered take
(Barkaszi et al., 2012), there is a lack of notable adverse dolphin
reactions to airgun noise despite a large body of observational data.
Therefore, the removal of the conditional shutdown measure for small
delphinids is warranted in consideration of the available information
regarding the effectiveness of such measures in mitigating impacts to
small delphinids and the practicability of such measures. No shutdown
is required for these species.
We proposed a number of expanded shutdown requirements on
the basis of detections of certain species deemed particularly
sensitive (e.g., beaked whales) or of particular circumstances deemed
to warrant the expanded shutdown requirement (e.g., whales with
calves). These were all conditioned upon observation or detection of
these species or circumstances at any distance from the vessel. We
received several comments challenging the value of expanded shutdown
requirements at all and, while we disagree with these comments, we
agree that some reasonable distance limit should be placed on these
requirements in order to better focus the observational effort of PSOs
and to avoid the potential for numerous shutdowns based on uncertain
detections at great distance. Therefore, as described in greater detail
later in this section, we limit such expanded shutdown zones for
relevant species or circumstances to 1.5 km.
We eliminated a proposed requirement for shutdowns upon
observation of a diving sperm whale at any distance centered on the
forward track of the source vessel. We received several comments
indicating that this proposed requirement was unclear in terms of how
it was to be implemented, and that the benefit to the species was
poorly demonstrated. We agree with these comments.
We eliminated a proposed requirement for shutdowns upon
detection of fin whales at any distance (proposed for TGS only). As
stated in our Notice of Proposed IHAs, this requirement was proposed
only on the basis of a high predicted amount of exposures. Following
review of this requirement, we recognize that it would not be effective
in achieving the stated goal of reducing the overall amount of takes,
as any observed fin whale would still be within the Level B harassment
zone and thus taken. Therefore, this measure serves no meaningful
purpose while imposing an additional practicability burden on TGS.
We clarify that the proposed requirement to shut down upon
observation of an aggregation of marine mammals applies only to large
whales (i.e., baleen whales and sperm whales), as was our intent.
Several commenters interpreted the requirement as applying to all
marine mammals and noted that this would require a significant increase
in shutdowns as a result of the prevalence of observations of dolphins
in groups exceeding five (most dolphin species have average group sizes
larger than five). It has been common practice in prior issued IHAs for
similar activities to require such a measure for whale species;
however, we inadvertently omitted this key detail in describing the
proposed measure. Also, we remove the language regarding ``traveling,''
which had been proposed in a similar context as was discussed above for
small delphinids and which we have determined to be a poorly defined
condition.
Monitoring
We require that at least two acoustic PSOs have prior
experience (minimum 90 days) working in that role, on the basis of
discussion with experts who emphasized the critical importance of
experience for acoustic PSOs (e.g., Thode et al., 2017; pers. comm., D.
Epperson, BSEE). Our proposal required that only one acoustic PSO have
prior experience.
Below, we describe mitigation requirements in detail.
Mitigation-Related Monitoring
Monitoring by independent, dedicated, trained marine mammal
observers is required. Note that, although we discuss requirements
related only to observation of marine mammals, we hereafter use the
generic term ``protected species observer'' (PSO). Independent
observers are employed by a third-party observer provider; vessel crew
may not serve as PSOs. Dedicated observers are those who have no tasks
other than to conduct observational effort, record observational data,
and communicate with and instruct the survey operator (i.e., vessel
captain and crew) with regard to the presence of marine mammals and
mitigation requirements. Communication with the operator may include
brief alerts regarding maritime hazards. Trained PSOs have successfully
completed an approved PSO training course (see ``Monitoring and
Reporting''), and experienced PSOs have additionally gained a minimum
of 90 days at-sea experience working as a PSO during a deep penetration
seismic survey, with no more than 18 months having elapsed since the
conclusion of the relevant at-sea experience. Training and experience
is specific to either visual or acoustic PSO duties. An experienced
visual PSO must have completed approved, relevant training and must
have gained the requisite experience working as a visual PSO. An
experienced acoustic PSO must have completed a passive acoustic
monitoring (PAM) operator training course and must have gained the
requisite experience working as an acoustic PSO. Hereafter, we also
refer to acoustic PSOs as PAM operators.
NMFS expects to provide informal approval for specific training
courses as needed to approve PSO staffing plans. NMFS does not plan to
formally administer any training program or to sanction any specific
provider, but will approve courses that meet the curriculum and trainer
requirements specified herein (see ``Monitoring and Reporting''). We
expect to provide such approvals in context of the need to ensure that
PSOs have the necessary training to carry out their duties competently
while also approving applicant staffing plans quickly. In order for
PSOs to be approved, NMFS must review and approve PSO resumes
accompanied by a relevant training course information packet that
includes
[[Page 63346]]
the name and qualifications (i.e., experience, training completed, or
educational background) of the instructor(s), the course outline or
syllabus, and course reference material as well as a document stating
the PSO's successful completion of the course. Although NMFS must
affirm PSO approvals, third-party observer providers and/or companies
seeking PSO staffing should expect that observers having satisfactorily
completed approved training and with the requisite experience (if
required) will be quickly approved. A PSO may be trained and/or
experienced as both a visual PSO and PAM operator and may perform
either duty, pursuant to scheduling requirements. PSO watch schedules
shall be devised in consideration of the following restrictions: (1) A
maximum of two consecutive hours on watch followed by a break of at
least one hour between watches for visual PSOs (periods typical of
observation for research purposes and as used for airgun surveys in
certain circumstances (Broker et al., 2015)); (2) a maximum of four
consecutive hours on watch followed by a break of at least two
consecutive hours between watches for PAM operators; and (3) a maximum
of 12 hours observation per 24-hour period. Further information
regarding PSO requirements may be found in the ``Monitoring and
Reporting'' section, later in this document.
During survey operations (e.g., any day on which use of the
acoustic source is planned to occur; whenever the acoustic source is in
the water, whether activated or not), a minimum of two PSOs must be on
duty and conducting visual observations at all times during daylight
hours (i.e., from 30 minutes prior to sunrise through 30 minutes
following sunset) and 30 minutes prior to and during nighttime ramp-ups
of the airgun array (see ``Ramp-ups'' below). PSOs should use NOAA's
solar calculator (www.esrl.noaa.gov/gmd/grad/solcalc/) to determine
sunrise and sunset times at their specific location. We recognize that
certain daytime conditions (e.g., fog, heavy rain) may reduce or
eliminate effectiveness of visual observations; however, on-duty PSOs
shall remain alert for marine mammal observational cues and/or a change
in conditions.
All source vessels must carry a minimum of one experienced visual
PSO, who shall be designated as the lead PSO, coordinate duty schedules
and roles, and serve as primary point of contact for the operator.
However, while it is desirable for all PSOs to be qualified through
experience, we are also mindful of the need to expand the workforce by
allowing opportunity for newly trained PSOs to gain experience.
Therefore, the lead PSO shall devise the duty schedule such that
experienced PSOs are on duty with trained PSOs (i.e., those PSOs with
appropriate training but who have not yet gained relevant experience)
to the maximum extent practicable in order to provide necessary
mentorship.
With regard to specific observational protocols, we largely follow
those described in Appendix C of BOEM's PEIS (BOEM, 2014a). The lead
PSO shall determine the most appropriate observation posts that will
not interfere with navigation or operation of the vessel while
affording an optimal, elevated view of the sea surface; these should be
the highest elevation available on each vessel, with the maximum
viewable range from the bow to 90 degrees to port or starboard of the
vessel. PSOs shall coordinate to ensure 360[deg] visual coverage around
the vessel, and shall conduct visual observations using binoculars and
the naked eye while free from distractions and in a consistent,
systematic, and diligent manner. All source vessels must be equipped
with pedestal-mounted ``bigeye'' binoculars that will be available for
PSO use. Within these broad outlines, the lead PSO and PSO team will
have discretion to determine the most appropriate vessel- and survey-
specific system for implementing effective marine mammal observational
effort. Any observations of marine mammals by crew members aboard any
vessel associated with the survey, including chase vessels, should be
relayed to the source vessel and to the PSO team.
All source vessels must use a towed PAM system for potential
detection of marine mammals. The system must be monitored at all times
during use of the acoustic source, and acoustic monitoring must begin
at least 30 minutes prior to ramp-up. PAM operators must be
independent, and all source vessels shall carry a minimum of two
experienced PAM operators. PAM operators shall communicate all
detections to visual PSOs, when visual PSOs are on duty, including any
determination by the PSO regarding species identification, distance and
bearing and the degree of confidence in the determination. Further
detail regarding PAM system requirements may be found in the
``Monitoring and Reporting'' section, later in this document. The
effectiveness of PAM depends to a certain extent on the equipment and
methods used and competency of the PAM operator, but no established
standards are currently in place.
Visual monitoring must begin at least 30 minutes prior to ramp-up
(described below) and must continue until one hour after use of the
acoustic source ceases or until 30 minutes past sunset. If any marine
mammal is observed at any distance from the vessel, a PSO would record
the observation and monitor the animal's position (including latitude/
longitude of the vessel and relative bearing and estimated distance to
the animal) until the animal dives or moves out of visual range of the
observer. A PSO would continue to observe the area to watch for the
animal to resurface or for additional animals that may surface in the
area. Visual PSOs shall communicate all observations to PAM operators,
including any determination by the PSO regarding species
identification, distance, and bearing and the degree of confidence in
the determination.
As noted previously, all source vessels must carry a minimum of one
experienced visual PSO and two experienced PAM operators. The observer
designated as lead PSO (including the full team of visual PSOs and PAM
operators) must have experience as a visual PSO. The applicant may
determine how many additional PSOs are required to adequately fulfill
the requirements specified here. To summarize, these requirements are:
(1) 24-hour acoustic monitoring during use of the acoustic source; (2)
visual monitoring during use of the acoustic source by two PSOs during
all daylight hours, with one visual PSO on-duty during nighttime ramp-
ups; (3) maximum of two consecutive hours on watch followed by a
minimum of one hour off watch for visual PSOs and a maximum of four
consecutive hours on watch followed by a minimum of two consecutive
hours off watch for PAM operators; and (4) maximum of 12 hours of
observational effort per 24-hour period for any PSO, regardless of
duties.
PAM Malfunction--Emulating sensible protocols described by the New
Zealand Department of Conservation for airgun surveys conducted in New
Zealand waters (DOC, 2013), survey activity may continue for brief
periods of time when the PAM system malfunctions or is damaged.
Activity may continue for 30 minutes without PAM while the PAM operator
diagnoses the issue. If the diagnosis indicates that the PAM system
must be repaired to solve the problem, operations may continue for an
additional two hours without acoustic monitoring under the following
conditions:
[[Page 63347]]
Daylight hours and sea state is less than or equal to
Beaufort sea state (BSS) 4;
No marine mammals (excluding delphinids; see below)
detected solely by PAM in the exclusion zone (see below) in the
previous two hours;
NMFS is notified via email as soon as practicable with the
time and location in which operations began without an active PAM
system; and
Operations with an active acoustic source, but without an
operating PAM system, do not exceed a cumulative total of four hours in
any 24-hour period.
Exclusion Zone and Buffer Zone
An exclusion zone is a defined area within which occurrence of a
marine mammal triggers mitigation action intended to reduce potential
for certain outcomes, e.g., auditory injury, more severe disruption of
behavioral patterns. The PSOs shall establish and monitor a 500-m
exclusion zone and additional 500-m buffer zone (total 1,000 m) during
the pre-clearance period (see below) and a 500-m exclusion zone during
the ramp-up and operational periods. PSOs should focus their
observational effort within this 1-km zone, although animals observed
at greater distances should be recorded and mitigation action taken as
necessary (see below). These zones shall be based upon radial distance
from any element of the airgun array (rather than being based on the
center of the array or around the vessel itself). During use of the
acoustic source, occurrence of marine mammals within the buffer zone
(but outside the exclusion zone) should be communicated to the operator
to prepare for the potential shutdown of the acoustic source. Use of
the buffer zone in relation to ramp-up is discussed below under ``Ramp-
up.'' Further detail regarding the exclusion zone and shutdown
requirements is given under ``Exclusion Zone and Shutdown
Requirements.''
Ramp-Up
Ramp-up of an acoustic source is intended to provide a gradual
increase in sound levels, enabling animals to move away from the source
if the signal is sufficiently aversive prior to its reaching full
intensity. We infer on the basis of behavioral avoidance studies and
observations that this measure results in some reduced potential for
auditory injury and/or more severe behavioral reactions. Although this
measure is not proven and some arguments have been made that use of
ramp-up may not have the desired effect of aversion (which is itself a
potentially negative impact but assumed to be better than the
alternative), ramp-up remains a relatively low-cost, common-sense
component of standard mitigation for airgun surveys. Ramp-up is most
likely to be effective for more sensitive species (e.g., beaked whales)
with known behavioral responses at greater distances from an acoustic
source (e.g., Tyack et al., 2011; DeRuiter et al., 2013; Miller et al.,
2015).
The ramp-up procedure involves a step-wise increase in the number
of airguns firing and total array volume until all operational airguns
are activated and the full volume is achieved. Ramp-up is required at
all times as part of the activation of the acoustic source (including
source tests; see ``Miscellaneous Protocols'' for more detail) and may
occur at times of poor visibility, assuming appropriate acoustic
monitoring with no detections in the 30 minutes prior to beginning
ramp-up. Acoustic source activation should only occur at night where
operational planning cannot reasonably avoid such circumstances. For
example, a nighttime initial ramp-up following port departure is
reasonably avoidable and may not occur. Ramp-up may occur at night
following acoustic source deactivation due to line turn or mechanical
difficulty. The operator must notify a designated PSO of the planned
start of ramp-up as agreed-upon with the lead PSO; the notification
time should be at least 60 minutes prior to the planned ramp-up. A
designated PSO must be notified again immediately prior to initiating
ramp-up procedures and the operator must receive confirmation from the
PSO to proceed.
Ramp-up procedures follow the recommendations of IAGC (2015). Ramp-
up would begin by activating a single airgun (i.e., array element) of
the smallest volume in the array. Ramp-up continues in stages by
doubling the number of active elements at the commencement of each
stage, with each stage of approximately the same duration. Total
duration should not be less than approximately 20 minutes but maximum
duration is not prescribed and will vary depending on the total number
of stages. Von Benda-Beckmann et al. (2013), in a study of the
effectiveness of ramp-up for sonar, found that extending the duration
of ramp-up did not have a corresponding effect on mitigation benefit.
There will generally be one stage in which doubling the number of
elements is not possible because the total number is not even. This
should be the last stage of the ramp-up sequence. The operator must
provide information to the PSO documenting that appropriate procedures
were followed. Ramp-ups should be scheduled so as to minimize the time
spent with the source activated prior to reaching the designated run-
in. This approach is intended to ensure a perceptible increase in sound
output per increment while employing increments that produce similar
degrees of increase at each step.
PSOs must monitor a 1,000-m zone (or to the distance visible if
less than 1,000 m) for a minimum of 30 minutes prior to ramp-up (i.e.,
pre-clearance). The pre-clearance period may occur during any vessel
activity (i.e., transit, line turn). Ramp-up must be planned to occur
during periods of good visibility when possible; operators may not
target the period just after visual PSOs have gone off duty. Following
deactivation of the source for reasons other than mitigation, the
operator must communicate the near-term operational plan to the lead
PSO with justification for any planned nighttime ramp-up. Any suspected
patterns of abuse must be reported by the lead PSO to be investigated
by NMFS. Ramp-up may not be initiated if any marine mammal is within
the designated 1,000-m zone. If a marine mammal is observed within the
zone during the pre-clearance period, ramp-up may not begin until the
animal(s) has been observed exiting the zone or until an additional
time period has elapsed with no further sightings (i.e., 15 minutes for
small odontocetes and 30 minutes for all other species). PSOs will
monitor the 500-m exclusion zone during ramp-up, and ramp-up must cease
and the source shut down upon observation of marine mammals within or
approaching the zone.
Exclusion Zone and Shutdown Requirements
The PSOs must establish a minimum exclusion zone with a 500-m
radius as a perimeter around the outer extent of the airgun array
(rather than being delineated around the center of the array or the
vessel itself). If a marine mammal (other than the small delphinid
species discussed below) appears within or enters this zone, the
acoustic source must be shut down (i.e., power to the acoustic source
must be immediately turned off). If a marine mammal is detected
acoustically, the acoustic source must be shut down, unless the PAM
operator is confident that the animal detected is outside the exclusion
zone or that the detected species is not subject to the shutdown
requirement (see below).
The 500-m radial distance of the standard exclusion zone is
expected to contain sound levels exceeding peak pressure injury
criteria for all hearing groups other than, potentially, high-frequency
cetaceans, while also
[[Page 63348]]
providing a consistent, reasonably observable zone within which PSOs
would typically be able to conduct effective observational effort.
Although significantly greater distances may be observed from an
elevated platform under good conditions, we believe that 500 m is
likely regularly attainable for PSOs using the naked eye during typical
conditions. In addition, an exclusion zone is expected to be helpful in
avoiding more severe behavioral responses. Behavioral response to an
acoustic stimulus is determined not only by received level but by
context (e.g., activity state) including, importantly, proximity to the
source (e.g., Southall et al., 2007; Ellison et al., 2012; DeRuiter et
al., 2013). In prescribing an exclusion zone, we seek not only to avoid
most potential auditory injury but also to reduce the likely severity
of the behavioral response at a given received level of sound.
As discussed in our Notice of Proposed IHAs, use of monitoring and
shutdown measures within defined exclusion zone distances is inherently
an essentially instantaneous proposition--a rule or set of rules that
requires mitigation action upon detection of an animal. This indicates
that defining an exclusion zone on the basis of cSEL thresholds, which
require that an animal accumulate some level of sound energy exposure
over some period of time (e.g., 24 hours), has questionable relevance
as a standard protocol for mobile sources, given the relative motion of
the source and the animals. A PSO aboard a mobile source will typically
have no ability to monitor an animal's position relative to the
acoustic source over relevant time periods for purposes of
understanding whether auditory injury is likely to occur on the basis
of cumulative sound exposure and, therefore, whether action should be
taken to avoid such potential.
Cumulative SEL thresholds are more relevant for purposes of
modeling the potential for auditory injury than they are for dictating
real-time mitigation, though they can be informative (especially in a
relative sense). We recognize the importance of the accumulation of
sound energy to an understanding of the potential for auditory injury
and that it is likely that, at least for low-frequency cetaceans, some
potential auditory injury is likely impossible to fully avoid and
should be considered for authorization.
Considering both the dual-metric thresholds described previously
(and shown in Table 3) and hearing group-specific marine mammal
auditory weighting functions in the context of the airgun sources
considered here, auditory injury zones indicated by the peak pressure
metric are expected to be predominant for both mid- and high-frequency
cetaceans, while zones indicated by cSEL criteria are expected to be
predominant for low-frequency cetaceans. Assuming source levels
provided by the applicants and indicated in Table 1 and spherical
spreading propagation, distances for exceedance of group-specific peak
injury thresholds were calculated and are shown in Table 5.
Consideration of auditory injury zones based on cSEL criteria are
dependent on the animal's generalized hearing range and how that
overlaps with the frequencies produced by the sound source of interest
in relation to marine mammal auditory weighting functions (NMFS, 2018).
As noted above, these are expected to be predominant for low-frequency
cetaceans because their most susceptible hearing range overlaps the low
frequencies produced by airguns, while the modeling indicates that
zones based on peak pressure criteria dominate for mid- and high-
frequency cetaceans. As described in detail in our Notice of Proposed
IHAs, we obtained unweighted spectrum data (modeled in 1 Hz bands) for
a reasonably equivalent acoustic source (i.e., a 36-airgun array with
total volume of 6,600 in\3\) in order to evaluate notional zone sizes
and to incorporate NMFS's technical guidance weighting functions over
an airgun array's full acoustic band. Using NMFS's associated User
Spreadsheet with hearing group-specific weighted source levels, and
inputs assuming spherical spreading propagation, a source velocity of
4.5 kn, shot intervals specified by the applicants, and pulse duration
of 100 ms, we calculated potential radial distances to auditory injury
zones (shown in Table 5).
Therefore, our 500-m exclusion zone contains the entirety of any
potential injury zone for mid-frequency cetaceans (realistically, there
is no such zone, as discussed above in ``Estimated Take''), while the
zones within which injury could occur may be larger for high-frequency
cetaceans (on the basis of peak pressure and depending on the specific
array) and for low-frequency cetaceans (on the basis of cumulative
sound exposure). Only three species of high-frequency cetacean could
occur in the planned survey areas: The harbor porpoise and two species
of the Family Kogiidae. Harbor porpoise are expected to occur rarely
and only in the northern portion of the survey area. However, we
require an extended shutdown measure for Kogia spp. to address these
potential injury concerns (described later in this section).
In summary, our goal in prescribing a standard exclusion zone
distance is to (1) encompass zones for most species within which
auditory injury could occur on the basis of instantaneous exposure; (2)
provide protection from the potential for more severe behavioral
reactions (e.g., panic, antipredator response) for marine mammals at
relatively close range to the acoustic source; (3) enable more
effective implementation of required mitigation by providing
consistency and ease of implementation for PSOs, who need to monitor
and implement the exclusion zone; and (4) to define a distance within
which detection probabilities are reasonably high for most species
under typical conditions. Our use of 500 m as the zone is not based
directly on any quantitative understanding of the range at which
auditory injury would be entirely precluded or any range specifically
related to disruption of behavioral patterns. Rather, we believe it is
a reasonable combination of factors. This zone has been proven as a
feasible measure through past implementation by operators in the Gulf
of Mexico (GOM; as regulated by BOEM pursuant to the Outer Continental
Shelf Lands Act (OCSLA) (43 U.S.C. 1331-1356)). In summary, a
practicable criterion such as this has the advantage of familiarity and
simplicity while still providing in most cases a zone larger than
relevant auditory injury zones, given realistic movement of source and
receiver. Increased shutdowns, without a firm idea of the outcome the
measure seeks to avoid, simply displace survey activity in time and
increase the total duration of acoustic influence as well as total
sound energy in the water (due to additional ramp-up and overlap where
data acquisition was interrupted).
Dolphin Exception--The shutdown requirement described above is in
place for all marine mammals, with the exception of small delphinids.
As defined here, the small delphinid group is intended to encompass
those members of the Family Delphinidae most likely to voluntarily
approach the source vessel for purposes of interacting with the vessel
and/or airgun array (e.g., bow-riding). This exception to the shutdown
requirement applies solely to specific genera of small dolphins--Steno,
Tursiops, Stenella, Delphinus, Lagenorhynchus, and Lagenodelphis (see
Table 2)--and applies under all circumstances, regardless of what the
perception of the animal(s) behavior or intent may be. Variations of
this measure that include exceptions based on animal behavior--
including that
[[Page 63349]]
described in our Notice of Proposed IHAs, in which an exception was
proposed to be applied only to ``traveling'' dolphins--have been
proposed by both NMFS and BOEM and have been criticized, in part due to
the subjective on-the-spot decision-making this scheme would require of
PSOs. If the mitigation requirements are not sufficiently clear and
objective, the outcome may be differential implementation across
surveys as informed by individual PSOs' experience, background, and/or
training. The exception described here is based on several factors: The
lack of evidence of or presumed potential for the types of effects to
these species of small delphinid that our shutdown requirement for
other species seeks to avoid, the uncertainty and subjectivity
introduced by such a decision framework, and the practicability concern
presented by the operational impacts. Despite a large volume of
observational effort during airgun surveys, including in locations
where dolphin shutdowns have not previously been required (i.e., the
U.S. GOM and United Kingdom (UK) waters), we are not aware of accounts
of notable adverse dolphin reactions to airgun noise (Stone, 2015a;
Barkaszi et al., 2012) other than one isolated incident (Gray and Van
Waerebeek, 2011). Dolphins have a relatively high threshold for the
onset of auditory injury (i.e., PTS) and more severe adverse behavioral
responses seem less likely given the evidence of purposeful approach
and/or maintenance of proximity to vessels with operating airguns.
The best available scientific evidence indicates that auditory
injury as a result of airgun sources is extremely unlikely for mid-
frequency cetaceans, primarily due to a relative lack of sensitivity
and susceptibility to noise-induced hearing loss at the frequency range
output by airguns (i.e., most sound below 500 Hz) as shown by the mid-
frequency cetacean auditory weighting function (NMFS, 2018). Criteria
for TTS in mid-frequency cetaceans for impulsive sounds were derived by
experimental measurement of TTS in beluga whales exposed to pulses from
a seismic watergun; dolphins exposed to the same stimuli in this study
did not display TTS (Finneran et al., 2002). Moreover, when the
experimental watergun signal was weighted appropriately for mid-
frequency cetaceans, less energy was filtered than would be the case
for an airgun signal. More recently, Finneran et al. (2015) exposed
bottlenose dolphins to repeated pulses from an airgun and measured no
TTS.
We caution that, while dolphins are observed voluntarily
approaching source vessels (e.g., bow-riding or interacting with towed
gear), the reasons for the behavior are unknown. In context of an
active airgun array, the behavior cannot be assumed to be harmless.
Although bow-riding comprises approximately 30 percent of behavioral
observations in the GOM, there is a much lower incidence of the
behavior when the acoustic source is active (Barkaszi et al., 2012),
and this finding was replicated by Stone (2015a) for surveys occurring
in UK waters. There appears to be evidence of aversive behavior by
dolphins during firing of airguns. Barkaszi et al. (2012) found that
the median closest distance of approach to the acoustic source was at
significantly greater distances during times of full-power source
operation when compared to silence, while Stone (2015a) and Stone and
Tasker (2006) reported that behavioral responses, including avoidance
and changes in swimming or surfacing behavior, were evident for
dolphins during firing of large arrays. Goold and Fish (1998) described
a ``general pattern of localized disturbance'' for dolphins in the
vicinity of an airgun survey. However, while these general findings--
typically, dolphins will display increased distance from the acoustic
source, decreased prevalence of ``bow-riding'' activities, and
increases in surface-active behaviors--are indicative of adverse or
aversive responses that may rise to the level of ``take'' (as defined
by the MMPA), they are not indicative of any response of a severity
such that the need to avoid it outweighs the impact on practicability
for the industry and operators.
Additionally, increased shutdowns resulting from such a measure
would require source vessels to revisit the missed track line to
reacquire data, resulting in an overall increase in the total sound
energy input to the marine environment and an increase in the total
duration over which the survey is active in a given area. Therefore,
the removal of such measures for small delphinids is warranted in
consideration of the available information regarding the effectiveness
of such measures in mitigating impacts to small delphinids and the
practicability of such measures.
Although other mid-frequency hearing specialists (e.g., large
delphinids) are considered no more likely to incur auditory injury than
are small delphinids, they are more typically deep divers, meaning that
there is some increased potential for more severe effects from a
behavioral reaction, as discussed in greater detail in ``Comments and
Responses.'' Therefore, we anticipate benefit from a shutdown
requirement for large delphinids in that it is likely to preclude more
severe behavioral reactions for any such animals in close proximity to
the source vessel as well as any potential for physiological effects.
At the same time, large delphinids are much less likely to approach
vessels. Therefore, a shutdown requirement for large delphinids would
not have similar impacts as a small delphinid shutdown in terms of
either practicability for the applicant or corollary increase in sound
energy output and time on the water.
Other Shutdown Requirements--Shutdown of the acoustic source is
also required in the event of certain other observations beyond the
standard 500-m exclusion zone. In our Notice of Proposed IHAs, we
proposed to condition these shutdowns upon detection of the relevant
species or circumstances at any distance. Following review of public
comments, we determined it appropriate to limit such shutdown
requirements to within a reasonable detection radius of 1.5 km. This
maintains the intent of the measures as originally proposed, i.e., to
provide for additional real-time protection by limiting the intensity
and duration of acoustic exposures for certain species or in certain
circumstances, while reducing the area over which PSOs must maintain
observational effort. As for normal shutdowns within the standard 500-m
exclusion zone, shutdowns at extended distance should be made on the
basis of confirmed detections (visual or acoustic) within the zone.
We determined an appropriate distance on the basis of available
information regarding detection functions for relevant species, but
note that, while based on quantitative data, the distance is an
approximate limit that is merely intended to encompass the region
within which we would expect a relatively high degree of success in
sighting certain species while also improving PSO efficacy by removing
the potential that a PSO might interpret these requirements as
demanding a focus on areas further from the vessel. For each modeled
taxon, Roberts et al. (2016) fitted detection functions that modeled
the detectability of the taxon according to distance from the trackline
and other covariates (i.e., the probability of detecting an animal
given its distance from the transect). These functions were based on
nearly 1.1 million linear km of line-transect survey effort conducted
from 1992-2014, with surveys arranged in aerial and shipboard
hierarchies and further grouped according to similarity
[[Page 63350]]
of observation protocol and platform. Where a taxon was sighted
infrequently, a detection function was fit to pooled sightings of
suitable proxy species. For example, for the North Atlantic right whale
and shipboard binocular surveys (i.e., the relevant combination of
platform and protocol), a detection function was fit using pooled
sightings of right whales and other mysticete species (Roberts et al.,
2015p). The resulting detection function shows a slightly more than 20
percent probability of detecting right whales at 2 km, with a mean
effective strip half-width (ESHW) (which provides a measure of how far
animals are seen from the transect line; Buckland et al., 2001) of
1,309 m (Roberts et al., 2015p). Similarly, Barlow et al. (2011)
reported mean ESHWs for various mysticete species ranging from
approximately 1.5-2 km. The detection function used in modeling density
for beaked whales provided a mean ESHW of 1,587 m (Roberts et al.,
2015l). Therefore, we set the shutdown radius for special circumstances
(described below) at 1.5 km.
Comments disagreeing with our proposal to require shutdowns upon
certain detections at any distance also suggested that the measures did
not have commensurate benefit for the relevant species. However, it
must be noted that any such observations would still be within range of
where behavioral disturbance of some form and degree would be likely to
occur (Table 4). While visual PSOs should focus observational effort
within the vicinity of the acoustic source and vessel, this does not
preclude them from periodic scanning of the remainder of the visible
area or from noting observations at greater distances, and there is no
reason to believe that such periodic scans by professional PSOs would
hamper the ability to maintain observation of areas closer to the
source and vessel. Circumstances justifying shutdown at extended
distance (i.e., within 1.5 km) include:
Upon detection of a right whale. Recent data concerning
the North Atlantic right whale, one of the most endangered whale
species (Best et al., 2001), indicate uncertainty regarding the
population's recovery and a possibility of decline (see discussion
under ``Description of Marine Mammals in the Area of the Specified
Activities''). We believe it appropriate to eliminate potential effects
to individual right whales to the extent possible;
Upon visual observation of a large whale (i.e., sperm
whale or any baleen whale) with calf, with ``calf'' defined as an
animal less than two-thirds the body size of an adult observed to be in
close association with an adult. Groups of whales are likely to be more
susceptible to disturbance when calves are present (e.g., Bauer et al.,
1993), and disturbance of cow-calf pairs could potentially result in
separation of vulnerable calves from adults. Separation, if it
occurred, could be exacerbated by airgun signals masking communication
between adults and the separated calf (Videsen et al., 2017). Absent
separation, airgun signals can disrupt or mask vocalizations essential
to mother-calf interactions. Given the consequences of potential loss
of calves in the context of ongoing UMEs for multiple mysticete
species, as well as the functional sensitivity of the mysticete whales
to frequencies associated with airgun survey activity, we believe this
measure is warranted;
Upon detection of a beaked whale or Kogia spp. These
species are behaviorally sensitive deep divers and it is possible that
disturbance could provoke a severe behavioral response leading to
injury (e.g., Wursig et al., 1998; Cox et al., 2006). We recognize that
there are generally low detection probabilities for beaked whales and
Kogia spp., meaning that many animals of these species may go
undetected. Barlow (1999) estimates such probabilities at 0.23 to 0.45
for Cuvier's and Mesoplodont beaked whales, respectively. However,
Barlow and Gisiner (2006) predict a roughly 24-48 percent reduction in
the probability of detecting beaked whales during seismic mitigation
monitoring efforts as compared with typical research survey efforts,
and Moore and Barlow (2013) noted a decrease in g(0) for Cuvier's
beaked whales from 0.23 at BSS 0 (calm) to 0.024 at BSS 5. Similar
detection probabilities have been noted for Kogia spp., though they
typically travel in smaller groups and are less vocal, thus making
detection more difficult (Barlow and Forney, 2007). As discussed
previously in this document (see ``Estimated Take''), there are high
levels of predicted exposures for beaked whales in particular.
Additionally for high-frequency cetaceans such as Kogia spp., auditory
injury zones relative to peak pressure thresholds may range from
approximately 350-1,550 m from the acoustic source, depending on the
specific array characteristics (NMFS, 2018); and
Upon visual observation of an aggregation (defined as six
or more animals) of large whales of any species. Under these
circumstances, we assume that the animals are engaged in some important
behavior (e.g., feeding, socializing) that should not be disturbed.
Shutdown Implementation Protocols--Any PSO on duty has the
authority to delay the start of survey operations or to call for
shutdown of the acoustic source. When shutdown is called for by a PSO,
the acoustic source must be immediately deactivated and any dispute
resolved only following deactivation. The operator must establish and
maintain clear lines of communication directly between PSOs on duty and
crew controlling the acoustic source to ensure that shutdown commands
are conveyed swiftly while allowing PSOs to maintain watch; hand-held
UHF radios are recommended. When both visual PSOs and PAM operators are
on duty, all detections must be immediately communicated to the
remainder of the on-duty team for potential verification of visual
observations by the PAM operator or of acoustic detections by visual
PSOs and initiation of dialogue as necessary. When there is certainty
regarding the need for mitigation action on the basis of either visual
or acoustic detection alone, the relevant PSO(s) must call for such
action immediately.
Upon implementation of shutdown, the source may be reactivated
after the animal(s) has been observed exiting the exclusion zone or
following a 30-minute clearance period with no further detection of the
animal(s). For harbor porpoise--the only small odontocete for which
shutdown is required--this clearance period is limited to 15 minutes.
If the acoustic source is shut down for reasons other than
mitigation (e.g., mechanical difficulty) for brief periods (i.e., less
than 30 minutes), it may be activated again without ramp-up if PSOs
have maintained constant visual and acoustic observation and no visual
detections of any marine mammal have occurred within the exclusion zone
and no acoustic detections have occurred. We define ``brief periods''
in keeping with other clearance watch periods and to avoid unnecessary
complexity in protocols for PSOs. For any longer shutdown (e.g., during
line turns), pre-clearance watch and ramp-up are required. For any
shutdown at night or in periods of poor visibility (e.g., BSS 4 or
greater), ramp-up is required but if the shutdown period was brief and
constant observation maintained, pre-clearance watch is not required.
Power-Down
Power-down, as defined here, refers to reducing the array to a
single element as a substitute for full shutdown. Use of a single
airgun as a ``mitigation source,''
[[Page 63351]]
e.g., during extended line turns, is not allowed. In a power-down
scenario, it is assumed that reducing the size of the array to a single
element reduces the ensonified area such that an observed animal is
outside of any area within which injury or more severe behavioral
reactions could occur. Here, power-down is not allowed for any reason
(e.g., to avoid pre-clearance and/or ramp-up).
Miscellaneous Protocols
The acoustic source must be deactivated when not acquiring data or
preparing to acquire data, except as necessary for testing. Unnecessary
use of the acoustic source should be avoided. Firing of the acoustic
source at any volume above the stated production volume is not
authorized for these IHAs; the operator must provide information to the
lead PSO at regular intervals confirming the firing volume. Notified
operational capacity (not including redundant backup airguns) must not
be exceeded during the survey, except where unavoidable for source
testing and calibration purposes. All occasions where activated source
volume exceeds notified operational capacity must be noticed to the
PSO(s) on duty and fully documented for reporting. The lead PSO must be
granted access to relevant instrumentation documenting acoustic source
power and/or operational volume.
Testing of the acoustic source involving all elements requires
normal mitigation protocols (e.g., ramp-up). Testing limited to
individual source elements or strings does not require ramp-up but does
require pre-clearance.
Restriction Areas
Below we provide discussion of various time-area restrictions.
Because the purpose of these areas is to reduce the likelihood of
exposing animals within the designated areas to noise from airgun
surveys that is likely to result in harassment, we require that source
vessels maintain minimum standoff distances (i.e., buffers) from the
areas. Sound propagation modeling results provided for a notional large
airgun array in BOEM's PEIS indicate that a 10 km distance would likely
contain received levels of sound exceeding 160 dB rms under a wide
variety of conditions (e.g., 21 scenarios encompassing four depth
regimes, four seasons, two bottom types). See Appendix D of BOEM's PEIS
for more detail. The 95 percent ranges (i.e., the radius of a circle
encompassing 95 percent of grid points equal to or greater than the 160
dB threshold value) provided in Table D-22 of BOEM's PEIS range from
4,959-9,122 m, with mean of 6,838 m. We adopt a standard 10-km buffer
distance to avoid ensonification above 160 dB rms of restricted areas
under most circumstances.
Coastal Restriction--No survey effort may occur within 30 km of the
coast. The intent of this restriction is to provide additional
protection for coastal stocks of bottlenose dolphin, all of which are
designated as depleted under the MMPA. This designation for all current
coastal stocks is retained from the originally delineated single
coastal migratory stock, which was revised to recognize the existence
of multiple stocks in 2002 (Waring et al., 2016). The prior single
coastal stock was designated as depleted because it was determined to
be below the optimum sustainable population level (i.e., the number of
animals that will result in the maximum productivity of the population,
keeping in mind the carrying capacity of their ecosystem) (Waring et
al., 2001). Already designated as depleted, a UME affected bottlenose
dolphins along the Atlantic coast, from New York to Florida, from 2013-
15. Genetic analyses performed to date indicate that 99 percent of
dolphins impacted were of the coastal ecotype, which may be expected to
typically occur within 20 km of the coast. As described above, a 10 km
buffer is provided to encompass the area within which sound exceeding
160 dB rms would reasonably be expected to occur. Further discussion of
this UME is provided under ``Description of Marine Mammals in the Area
of the Specified Activity.''
North Atlantic Right Whale--From November through April, no survey
effort may occur within 90 km of the coast. In our Notice of Proposed
IHAs, we proposed a similar restriction out to 47 km. The proposed 47-
km seasonal restriction of survey effort was intended to avoid
ensonification by levels of sound expected to result in behavioral
harassment of particular areas of expected importance for North
Atlantic right whales, including designated critical habitat, vessel
speed limit seasonal management areas (SMAs), a coastal strip
containing SMAs, and vessel speed limit dynamic management areas
(DMAs). This area was expected to provide substantial protection of
right whales within the migratory corridor and calving and nursery
grounds. However, following review of comments received from the Marine
Mammal Commission, as well as other public comments received and as a
result of the continued deterioration of the status of this population
(described previously in ``Description of Marine Mammals in the Area of
the Specified Activity''), we considered new information regarding
predicted right whale distribution (e.g., Roberts et al., 2017; Davis
et al., 2017) and re-evaluated the proposed right whale time-area
restriction.
Specifically, we became aware of an effort by Roberts et al. to
update the 2015 North Atlantic right whale density models. As described
in Roberts et al. (2017), the updates greatly expanded the dataset used
to derive density outputs, especially within the planned survey area,
as they incorporated a key dataset that was not included in the 2015
model version: Aerial surveys conducted over multiple years by several
organizations in the southeast United States. In addition, the AMAPPS
survey data were incorporated into the revised models. By including
these additional data sources, the number of right whale sightings used
to inform the model within the planned survey area increased by
approximately 2,500 sightings (approximately 40 sightings informing the
2015 models versus approximately 2,560 sightings informing the updated
2017 models). In addition, these models incorporated several
improvements to minimize known biases and used an improved seasonal
definition that more closely aligns with right whale biology.
Importantly, the revised models showed a strong relationship between
right whale abundance in the mid-Atlantic during the winter (December-
March) and distance to shore out to approximately 80 km (Roberts et
al., 2017), which was previously estimated out to approximately 50 km
(Roberts et al., 2015p). As described above, a 10 km buffer is provided
to encompass the area within which sound exceeding 160 dB rms would
reasonably be expected to occur. Mid-Atlantic SMAs for vessel speed
limits are in effect from November 1 through April 30, while southeast
SMAs are in effect from November 15 through April 15 (see 50 CFR
224.105). Therefore, the area discussed here for spatial mitigation
would be in effect from November 1 through April 30.
While we acknowledge that some whales may be present at distances
further offshore during the November through April restriction--though
whales are not likely to occur in waters deeper than 1,500 m--and that
there may be whales present during months outside the restriction
(e.g., Davis et al., 2017; Krzystan et al., 2018), we have accounted
for the best available information in reasonably limiting the potential
for acoustic exposure of right whales to levels exceeding harassment
thresholds. When coupled with the expanded shutdown provision described
previously for right whales,
[[Page 63352]]
the prescribed mitigation may reasonably be expected to eliminate most
potential for behavioral harassment of right whales.
However, as discussed above, in lieu of this requirement,
applicants may alternatively develop and submit a monitoring and
mitigation plan for NMFS's approval that would be sufficient to achieve
comparable protection for North Atlantic right whales. If approved,
applicants would be required to maintain a minimum coastal standoff
distance of 47 km from November through April while operating in
adherence with the approved plan from 47 through 80 km offshore. (Note
that the 80 km distance is assumed to represent to a reasonable extent
right whale occurrence on the migratory pathway; therefore, under an
approved plan the 10-km buffer would not be relevant.)
DMAs are associated with a scheme established by the final rule for
vessel speed limits (73 FR 60173; October 10, 2008; extended by 78 FR
73726; December 9, 2013) to reduce the risk of ship strike for right
whales. In association with those regulations, NMFS established a
program whereby vessels are requested, but not required, to abide by
speed restrictions or avoid locations when certain aggregations of
right whales are detected outside SMAs. Generally, the DMA construct is
intended to acknowledge that right whales can occur outside of areas
where they predictably and consistently occur due to, e.g., varying
oceanographic conditions that dictate prey concentrations. NMFS
establishes DMAs by surveying right whale habitat and, when a specific
aggregation is sighted, creating a temporary zone (i.e., DMA) around
the aggregation. DMAs are in effect for 15 days when designated and
automatically expire at the end of the period, but may be extended if
whales are re-sighted in the same area.
NMFS issues announcements of DMAs to mariners via its customary
maritime communication media (e.g., NOAA Weather radio, websites, email
and fax distribution lists) and any other available media outlets.
Information on the possibility of establishment of such zones is
provided to mariners through written media such as U.S. Coast Pilots
and Notice to Mariners including, in particular, information on the
media mariners should monitor for notification of the establishment of
a DMA. Upon notice via the above media of DMA designation, survey
operators must cease operation within 24 hours if within 10 km of the
boundary of a designated DMA and may not conduct survey operations
within 10 km of a designated DMA during the period in which the DMA is
active. It is the responsibility of the survey operators to monitor
appropriate media and to be aware of designated DMAs.
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Other Species--Predicted acoustic exposures are moderate to high
for certain potentially affected marine mammal species (see Table 6)
and, regardless of the absolute numbers of predicted exposures, the
scope of planned activities (i.e., survey activity throughout
substantial portions of many species range and for substantial portions
of the year) gives rise to concern regarding the impact on certain
potentially affected stocks. Therefore, we take the necessary step of
identifying additional spatiotemporal restrictions on survey effort, as
described here (Figure 4 and Table 7). In response to public comment,
where possible we conducted a quantitative assessment of take avoided
(described previously in ``Estimated Take''). Our qualitative
assessment leads us to believe that
[[Page 63354]]
implementation of these measures is expected to provide biologically
meaningful benefit for the affected animals by restricting survey
activity and the effects of the sound produced in areas of residency
and/or preferred habitat that support higher densities for the stocks
during substantial portions of the year.
The restrictions described here are primarily targeted towards
protection of sperm whales, beaked whales (i.e., Cuvier's beaked whale
or Mesoplodon spp. but not the northern bottlenose whale; see
``Description of Marine Mammals in the Area of the Specified
Activity''), and pilot whales. For all three species or guilds, the
amount of predicted exposures is moderate to high. The moderate to high
amount of predicted exposures in conjunction with other contextual
elements provides the impetus to develop appropriate restrictions.
Beaked whales are considered to be a particularly acoustically
sensitive species. The sperm whale is an endangered species, also
considered to be acoustically sensitive and potentially subject to
significant disturbance of important foraging behavior. Pilot whale
populations in U.S. waters of the Atlantic are considered vulnerable
due to high levels of mortality in commercial fisheries, and are
therefore likely to be less resilient to other stressors, such as
disturbance from the planned surveys.
In some cases, we expect substantial subsidiary benefit for
additional species that also find preferred habitat in the designated
area of restriction. In particular, Area #4 (Figure 4), although
delineated in order to specifically provide an area of anticipated
benefit to beaked whales, sperm whales, and pilot whales, is expected
to host a diverse cetacean fauna (e.g., McAlarney et al., 2015). Our
analysis (described below) indicates that species most likely to derive
subsidiary benefit from this time-area restriction include the
bottlenose dolphin, Risso's dolphin, and common dolphin. For species
with density predicted through stratified models, similar analysis is
not possible and assumptions regarding potential benefit of time-area
restrictions are based on known ecology of the species and sightings
patterns and are less robust. Nevertheless, subsidiary benefit for
Areas #1-3 (Figure 4) should be expected for species known to be
present in these areas (e.g., assumed affinity for slope/abyss areas
off Cape Hatteras): Kogia spp., pantropical spotted dolphin, Clymene
dolphin, and rough-toothed dolphin.
We described our rationale for and development of these time-area
restrictions in detail in our Notice of Proposed IHAs; please see that
document for more detail. Literature newly available since publication
of the Notice of Proposed IHAs provides additional support for the
importance of these areas. For example, McLellan et al. (2018),
reporting the results of aerial surveys conducted from 2011-2015,
provide additional confirmation that a portion of the region described
below as Area #4 (``Hatteras and North'') hosts high densities of
beaked whales, concluding that the area off Cape Hatteras at the
convergence of the Labrador Current and Gulf Stream is a particularly
important habitat for several species of beaked whales. Stanistreet et
al. (2017) report the results of a multi-year (2011-2015) passive
acoustic monitoring effort to assess year-round marine mammal
occurrence along the continental slope, including four locations within
the planned survey area (i.e., Norfolk Canyon, Cape Hatteras, Onslow
Bay, and Jacksonville) and, in this paper, they further document the
presence of beaked whales in Area #4. Stanistreet et al. (2018) report
the results of this study for sperm whale occurrence at the same sites
along the continental slope. These results showed that sperm whales
were present frequently at the first three sites, with few detections
at Jacksonville. The greatest monitoring effort was conducted at the
Cape Hatteras site, where detections were made on 65 percent of 734
recording days across all seasons. In addition to having the highest
detection rate of sites within the specific geographic region (in
conjunction with roughly double the amount of recording effort compared
with the next highest site), Cape Hatteras exhibited the most distinct
seasonal pattern of any recording site (Stanistreet et al., 2018). The
authors reported consistently higher sperm whale occurrence at Cape
Hatteras during the winter than any other season. On the basis of this
new information, we shifted the timing of the seasonal restriction in
Area #4 from July through September (as proposed) to January through
March (i.e., ``winter''; Stanistreet et al., 2018). Our previously
proposed timing of the seasonal restriction was based on barely
discernable distribution shifts based on monthly model predictions
(Roberts et al., 2016). However, the revised timing, as indicated by
Stanistreet et al. (2018), is generally consistent with the seasonal
shift in sperm whale concentrations previously described in the western
North Atlantic (Perry et al., 1999, Waring et al., 2014).
Please note that, following review of public comments, former Area
#1 was eliminated from consideration (discussed in greater detail under
``Comments and Responses''). Therefore, numbering of areas described
here has shifted down by one as compared with the discussion presented
in our Notice of Proposed IHAs, i.e., former Area #5 is now Area #4,
etc. In order to consider potential restriction of survey effort in
time and space, we considered the outputs of habitat-based predictive
density models (Roberts et al., 2016) as well as available information
concerning focused marine mammal studies within the survey areas, e.g.,
photo-identification, telemetry, acoustic monitoring. The latter
information was used primarily to provide verification for some of the
areas and times considered, and helps to confirm that areas of high
predicted density are in fact preferred habitat for these species. We
used the density model outputs by creating core abundance areas, i.e.,
an area that contains some percentage of predicted abundance for a
given species or species group. We were not able to consider core
abundance areas for species with stratified models showing uniform
density; however, this information informs us as to whether those
species may receive subsidiary benefit from a given time-area
restriction.
A core abundance area is the smallest area that represents a given
percentage of abundance. As described in our Notice of Proposed IHAs,
we created a range of core abundance areas for each species of interest
and determined that in most cases the 25 percent core abundance area
best balanced adequate protection for the target species with concerns
regarding practicability for applicants. The larger the percentage of
abundance captured, the larger the area. However, Area #4 was designed
as a conglomerate by merging areas indicated to be important through
the core abundance analysis and available scientific literature for
beaked whales, pilot whales, and sperm whales. In particular, for sperm
whales (which are predicted to be broadly distributed on the slope
throughout the year), we included an area predicted to consistently
host higher relative densities in all months (corresponding with the
five percent core abundance threshold). We assessed different levels of
core abundance in order to define a relatively restricted area of
preferred habitat across all seasons. This area in the vicinity of the
shelf break to the north of Cape Hatteras (which forms the
[[Page 63355]]
conglomerate Area #4), together with spatially separated canyon
features contained within the 25 percent core abundance areas and
previously identified as preferred habitat for beaked whales, form the
basis for our time-area restriction for sperm whales. Core abundance
maps are provided online at www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-atlantic.
In summary, we require the following time-area restrictions:
In order to protect coastal bottlenose dolphins, a 30-km
coastal strip (20 km plus 10 km buffer) would be closed to use of the
acoustic source year-round;
In order to protect the North Atlantic right whale, a 90-
km coastal strip (80 km plus 10 km buffer) would be closed to use of
the acoustic source from November through April (Figure 3) (or
comparable protection would be provided through implementation of a
NMFS-approved mitigation and monitoring plan at distances between 47-80
km offshore). Dynamic management areas (buffered by 10 km) are also
closed to use of the acoustic source when in effect;
The 10-km buffer is built into the areas defined below and in Table
7. Therefore, we do not separately mention the addition of the buffer.
Deepwater canyon areas. Areas #1-3 (Figure 4) are defined
in Table 7 and will be closed to use of the acoustic source year-round.
Although they may be protective of additional species (e.g., Kogia
spp.), Area #1 is expected to be particularly beneficial for beaked
whales and Areas #2-3 are expected to be particularly beneficial for
both beaked whales and sperm whales;
Shelf break off Cape Hatteras and to the north (``Hatteras
and North''), including slope waters around ``The Point.'' Area #4 is
defined in Table 7 and will be closed to use of the acoustic source
from January through March. Although this closure is expected to be
beneficial for a diverse species assemblage, Area #4 is expected to be
particularly beneficial for beaked whales, sperm whales, and pilot
whales.
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[[Page 63357]]
Table 7--Boundaries of Time-Area Restrictions Depicted in Figure 4
------------------------------------------------------------------------
Area Latitude Longitude
------------------------------------------------------------------------
1........................... 33[deg]31'16'' N 72[deg]52'07'' W
1........................... 33[deg]10'05'' N 72[deg]59'59'' W
1........................... 33[deg]11'23'' N 73[deg]19'36'' W
1........................... 33[deg]43'34'' N 73[deg]17'43'' W
1........................... 33[deg]59'43'' N 73[deg]10'16'' W
1........................... 34[deg]15'10'' N 72[deg]55'37'' W
1........................... 34[deg]14'02'' N 72[deg]36'00'' W
1........................... 34[deg]03'33'' N 72[deg]37'27'' W
1........................... 33[deg]53'00'' N 72[deg]44'31'' W
2........................... 34[deg]13'21'' N 74[deg]07'33'' W
2........................... 34[deg]00'07'' N 74[deg]26'41'' W
2........................... 34[deg]38'40'' N 75[deg]05'52'' W
2........................... 34[deg]53'24'' N 74[deg]51'11'' W
3........................... 36[deg]41'17'' N 71[deg]25'47'' W
3........................... 36[deg]43'20'' N 72[deg]13'25'' W
3........................... 36[deg]55'20'' N 72[deg]26'18'' W
3........................... 37[deg]52'21'' N 72[deg]22'31'' W
3........................... 37[deg]43'54'' N 72[deg]00'40'' W
3........................... 37[deg]09'52'' N 72[deg]04'31'' W
3........................... 36[deg]52'01'' N 71[deg]24'31'' W
4........................... 37[deg]08'30'' N 74[deg]01'42'' W
4........................... 36[deg]15'12'' N 73[deg]48'37'' W
4........................... 35[deg]53'14'' N 73[deg]49'02'' W
4........................... 34[deg]23'07'' N 75[deg]21'33'' W
4........................... 33[deg]47'37'' N 75[deg]27'25'' W
4........................... 33[deg]48'31'' N 75[deg]52'58'' W
4........................... 34[deg]23'57'' N 75[deg]52'50'' W
4........................... 35[deg]22'29'' N 74[deg]51'50'' W
4........................... 36[deg]32'31'' N 74[deg]49'31'' W
4........................... 37[deg]05'39'' N 74[deg]45'37'' W
4........................... 37[deg]27'53'' N 74[deg]32'40'' W
4........................... 38[deg]23'15'' N 73[deg]45'06'' W
4........................... 38[deg]11'17'' N 73[deg]06'36'' W
------------------------------------------------------------------------
Vessel Strike Avoidance
These measures apply to all vessels associated with the planned
survey activity (e.g., source vessels, chase vessels, supply vessels);
however, we note that these requirements do not apply in any case where
compliance would create an imminent and serious threat to a person or
vessel or to the extent that a vessel is restricted in its ability to
maneuver and, because of the restriction, cannot comply. These measures
include the following:
1. Vessel operators and crews must maintain a vigilant watch for
all marine mammals and slow down, stop their vessel, or alter course,
as appropriate and regardless of vessel size, to avoid striking any
marine mammal. A single marine mammal at the surface may indicate the
presence of submerged animals in the vicinity of the vessel; therefore,
precautionary measures should be exercised when an animal is observed.
A visual observer aboard the vessel must monitor a vessel strike
avoidance zone around the vessel (specific distances detailed below),
to ensure the potential for strike is minimized. Visual observers
monitoring the vessel strike avoidance zone can be either third-party
observers or crew members, but crew members responsible for these
duties must be provided sufficient training to distinguish marine
mammals from other phenomena and broadly to identify a marine mammal to
broad taxonomic group (i.e., as a right whale, other whale, or other
marine mammal). In this context, ``other whales'' includes sperm whales
and all baleen whales other than right whales;
2. All vessels, regardless of size, must observe the 10 kn speed
restriction in specific areas designated for the protection of North
Atlantic right whales: Any DMAs when in effect, the Mid-Atlantic SMAs
(from November 1 through April 30), and critical habitat and the
Southeast SMA (from November 15 through April 15). See
www.fisheries.noaa.gov/national/endangered-species-conservation/reducing-ship-strikes-north-atlantic-right-whales for more information
on these areas;
3. Vessel speeds must also be reduced to 10 kn or less when mother/
calf pairs, pods, or large assemblages of any marine mammal are
observed near a vessel;
4. All vessels must maintain a minimum separation distance of 500 m
from right whales. If a whale is observed but cannot be confirmed as a
species other than a right whale, the vessel operator must assume that
it is a right whale and take appropriate action;
5. All vessels must maintain a minimum separation distance of 100 m
from sperm whales and all other baleen whales;
6. All vessels must attempt to maintain a minimum separation
distance of 50 m from all other marine mammals, with an exception made
for those animals that approach the vessel; and
7. When marine mammals are sighted while a vessel is underway, the
vessel should take action as necessary to avoid violating the relevant
separation distance (e.g., attempt to remain parallel to the animal's
course, avoid excessive speed or abrupt changes in direction until the
animal has left the area). If marine mammals are sighted within the
relevant separation distance, the vessel should reduce speed and shift
the engine to neutral, not engaging the engines until animals are clear
of the area. This recommendation does not apply to any vessel towing
gear.
General Measures
All vessels associated with survey activity (e.g., source vessels,
chase vessels, supply vessels) must have a functioning Automatic
Identification System (AIS) onboard and operating at all times,
regardless of whether AIS would otherwise be required. Vessel names and
call signs must be provided to NMFS, and applicants must notify NMFS
when survey vessels are operating.
We have carefully evaluated the suite of mitigation measures
described here and considered a range of other measures in the context
of ensuring that we prescribe the means of effecting the least
practicable adverse impact on the affected marine mammal species and
stocks and their habitat. Based on our evaluation of these measures, we
have determined that the required mitigation measures provide the means
of effecting the least practicable adverse impact on marine mammal
species or stocks and their habitat, paying particular attention to
rookeries, mating grounds, and areas of similar significance.
Monitoring and Reporting
In order to issue an IHA for an activity, Section 101(a)(5)(D) of
the MMPA states that NMFS must set forth requirements pertaining to the
monitoring and reporting of the authorized taking. NMFS's MMPA
implementing regulations further describe the information that an
applicant should provide when requesting an authorization (50 CFR
216.104(a)(13)), including the means of accomplishing the necessary
monitoring and reporting that will result in increased knowledge of the
species and the level of taking or impacts on populations of marine
mammals. Effective reporting is critical both to compliance as well as
ensuring that the most value is obtained from the required monitoring.
Monitoring and reporting requirements prescribed by NMFS should
contribute to improved understanding of one or more of the following:
Occurrence of marine mammal species in action area (e.g.,
presence, abundance, distribution, density);
Nature, scope, or context of likely marine mammal exposure
to potential stressors/impacts (individual or cumulative, acute or
chronic), through better understanding of: (1) Action or environment
(e.g., source characterization, propagation, ambient noise); (2)
affected species (e.g., life history, dive patterns); (3) co-occurrence
of marine mammal species with the action; or (4) biological or
behavioral context of exposure (e.g., age, calving or feeding areas);
Individual marine mammal responses (behavioral or
physiological) to acoustic stressors (acute, chronic, or cumulative),
other stressors, or
[[Page 63358]]
cumulative impacts from multiple stressors;
How anticipated responses to stressors impact either: (1)
Long-term fitness and survival of individual marine mammals; or (2)
populations, species, or stocks;
Effects on marine mammal habitat (e.g., marine mammal prey
species, acoustic habitat, or important physical components of marine
mammal habitat); and
Mitigation and monitoring effectiveness.
Changes From the Notice of Proposed IHAs
Here we summarize substantive changes to monitoring and reporting
requirements from our Notice of Proposed IHAs. All changes were made on
the basis of review of public comments received and/or review of new
information.
As described in our Notice of Proposed IHAs, we
preliminarily reached small numbers findings for some species on the
basis of the proposed limitation of authorized take to approximately
one-third of the abundance estimate deemed at the time to be most
appropriate. In order to ensure that IHA-holders would not exceed this
cap without limiting the planned survey activity, we proposed to
require interim reporting in which IHA-holders would report all
observations of marine mammals as well as corrected numbers of marine
mammals ``taken.'' We received information from several commenters--
including several of the applicants--strongly indicating that such a de
facto limitation, coupled with a novel reporting requirement, was
impracticable. In summary, commenters noted that such surveys are
multi-million dollar endeavors and stated that the surveys would simply
not be conducted rather than commit such costs to the survey in the
face of significant uncertainty as to whether the survey might be
suddenly shut down as a result of reaching a pre-determined cap on the
basis of novel modeling of ``corrected'' takes. We also received many
comments indicating that our small numbers analyses were flawed and, as
described in detail later in this notice (see ``Small Numbers
Analyses'') we reconsidered the available information and re-evaluated
our analyses in response to these comments. As a result of our revised
small numbers analyses, such a cap coupled with reporting scheme is not
necessary. Further, we agree with commenters that the proposal
presented significant practicability concerns. Therefore, the proposed
``interim'' reporting requirement is eliminated.
Separately, while we recognize the importance of producing
the most accurate estimates of actual take possible, we agree that the
proposed approach to correcting observations to produce estimates of
actual takes was (1) not the best available approach; (2) is novel in
that it has not been previously required of applicants conducting
similar activities; and (3) may not be appropriate for application to
observations conducted from working source vessels. We have adopted a
different approach to performing these ``corrections,'' as recommended
through comment from the Marine Mammal Commission, but in this case we
will perform these corrections upon submission of reports from IHA-
holders and evaluate the appropriateness of this approach and the
validity of the results prior to requiring it for future IHAs.
As a result of concerns expressed through public comment,
we have revised requirements relating to reporting of injured or dead
marine mammals and have added newly crafted requirements relating to
actions that should be taken in response to stranding events in certain
circumstances.
Monitoring requirements are the same for all applicants, and a
single discussion is provided here.
PSO Eligibility and Qualifications
All PSO resumes must be submitted to NMFS and PSOs must be approved
by NMFS after a review of their qualifications. These qualifications
include whether the individual has successfully completed the necessary
training (see ``Training,'' below) and, if relevant, whether the
individual has the requisite experience (and is in good standing). PSOs
should provide a current resume and information related to PSO
training; submitted resumes should not include superfluous information.
Information related to PSO training should include (1) a course
information packet that includes the name and qualifications (e.g.,
experience, training, or education) of the instructor(s), the course
outline or syllabus, and course reference material; and (2) a document
stating the PSO's successful completion of the course. PSOs must be
trained biologists, with the following minimum qualifications:
A bachelor's degree from an accredited college or
university with a major in one of the natural sciences and a minimum of
30 semester hours or equivalent in the biological sciences and at least
one undergraduate course in math or statistics;
Experience and ability to conduct field observations and
collect data according to assigned protocols (may include academic
experience) and experience with data entry on computers;
Visual acuity in both eyes (correction is permissible)
sufficient for discernment of moving targets at the water's surface
with ability to estimate target size and distance; use of binoculars
may be necessary to correctly identify the target (required for visual
PSOs only);
Experience or training in the field identification of
marine mammals, including the identification of behaviors (required for
visual PSOs only);
Sufficient training, orientation, or experience with the
survey operation to ensure personal safety during observations;
Writing skills sufficient to prepare a report of
observations (e.g., description, summary, interpretation, analysis)
including but not limited to the number and species of marine mammals
observed; marine mammal behavior; and descriptions of activity
conducted and implementation of mitigation;
Ability to communicate orally, by radio or in person, with
survey personnel to provide real-time information on marine mammals
detected in the area as necessary; and
Successful completion of relevant training (described
below), including completion of all required coursework and passing (80
percent or greater) a written and/or oral examination developed for the
training program.
The educational requirements may be waived if the PSO has acquired
the relevant skills through alternate experience. Requests for such a
waiver must include written justification, and prospective PSOs granted
waivers must satisfy training requirements described below. Alternate
experience that may be considered includes, but is not limited to, the
following:
Secondary education and/or experience comparable to PSO
duties;
Previous work experience conducting academic, commercial,
or government-sponsored marine mammal surveys; and
Previous work experience as a PSO; the PSO should
demonstrate good standing and consistently good performance of PSO
duties.
Training--NMFS does not currently approve specific training
programs; however, acceptable training may include training previously
approved by BSEE, or training that adheres generally to the
recommendations provided by ``National Standards for a Protected
Species Observer and Data Management
[[Page 63359]]
Program: A Model Using Geological and Geophysical Surveys'' (Baker et
al., 2013). Those recommendations include the following topics for
training programs:
Life at sea, duties, and authorities;
Ethics, conflicts of interest, standards of conduct, and
data confidentiality;
Offshore survival and safety training;
Overview of oil and gas activities (including geophysical
data acquisition operations, theory, and principles) and types of
relevant sound source technology and equipment;
Overview of the MMPA and ESA as they relate to protection
of marine mammals;
Mitigation, monitoring, and reporting requirements as they
pertain to geophysical surveys;
Marine mammal identification, biology and behavior;
Background on underwater sound;
Visual surveying protocols, distance calculations and
determination, cues, and search methods for locating and tracking
different marine mammal species (visual PSOs only);
Optimized deployment and configuration of PAM equipment to
ensure effective detections of cetaceans for mitigation purposes (PAM
operators only);
Detection and identification of vocalizing species or
cetacean groups (PAM operators only);
Measuring distance and bearing of vocalizing cetaceans
while accounting for vessel movement (PAM operators only);
Data recording and protocols, including standard forms and
reports, determining range, distance, direction, and bearing of marine
mammals and vessels; recording GPS location coordinates, weather
conditions, Beaufort wind force and sea state, etc.;
Proficiency with relevant software tools;
Field communication/support with appropriate personnel,
and using communication devices (e.g., two-way radios, satellite
phones, internet, email, facsimile);
Reporting of violations, noncompliance, and coercion; and
Conflict resolution.
PAM operators should regularly refresh their detection skills
through practice with simulation-modeling software, and should keep up
to date with training on the latest software/hardware advances.
Visual Monitoring
The lead PSO is responsible for establishing and maintaining clear
lines of communication with vessel crew. The vessel operator shall work
with the lead PSO to accomplish this and shall ensure any necessary
briefings are provided for vessel crew to understand mitigation
requirements and protocols. While on duty, PSOs will continually scan
the water surface in all directions around the acoustic source and
vessel for presence of marine mammals, using a combination of the naked
eye and high-quality binoculars, from optimum vantage points for
unimpaired visual observations with minimum distractions. PSOs will
collect observational data for all marine mammals observed, regardless
of distance from the vessel, including species, group size, presence of
calves, distance from vessel and direction of travel, and any observed
behavior (including an assessment of behavioral responses to survey
activity). Upon observation of marine mammal(s), a PSO will record the
observation and monitor the animal's position (including latitude/
longitude of the vessel and relative bearing and estimated distance to
the animal) until the animal dives or moves out of visual range of the
observer, and a PSO will continue to observe the area to watch for the
animal to resurface or for additional animals that may surface in the
area. PSOs will also record environmental conditions at the beginning
and end of the observation period and at the time of any observations,
as well as whenever conditions change significantly in the judgment of
the PSO on duty.
The vessel operator must provide bigeye binoculars (e.g., 25 x 150;
2.7 view angle; individual ocular focus; height control) of appropriate
quality (e.g., Fujinon or equivalent) solely for PSO use. These should
be pedestal-mounted on the deck at the most appropriate vantage point
that provides for optimal sea surface observation, PSO safety, and safe
operation of the vessel. The operator must also provide a night-vision
device suited for the marine environment for use during nighttime ramp-
up pre-clearance, at the discretion of the PSOs. NVDs may include night
vision binoculars or monocular or forward-looking infrared device
(e.g., Exelis PVS-7 night vision goggles; Night Optics D-300 night
vision monocular; FLIR M324XP thermal imaging camera or equivalents).
At minimum, the device should feature automatic brightness and gain
control, bright light protection, infrared illumination, and optics
suited for low-light situations. Other required equipment, which should
be made available to PSOs by the third-party observer provider,
includes reticle binoculars (e.g., 7 x 50) of appropriate quality
(e.g., Fujinon or equivalent), GPS, digital single-lens reflex camera
of appropriate quality (e.g., Canon or equivalent), compass, and any
other tools necessary to adequately perform the tasks described above,
including accurate determination of distance and bearing to observed
marine mammals.
Individuals implementing the monitoring protocol will assess its
effectiveness using an adaptive approach. Monitoring biologists will
use their best professional judgment throughout implementation and seek
improvements to these methods when deemed appropriate. Specifically,
implementation of shutdown requirements will be made on the basis of
the PSO's best professional judgment. While PSOs should not insert
undue ``precaution'' into decision-making, it is expected that PSOs may
call for mitigation action on the basis of reasonable certainty
regarding the need for such action, as informed by professional
judgment. Any modifications to protocol will be coordinated between
NMFS and the applicant.
Acoustic Monitoring
Monitoring of a towed PAM system is required at all times, from 30
minutes prior to ramp-up and throughout all use of the acoustic source.
Towed PAM systems generally consist of hardware (e.g., hydrophone
array, cables) and software (e.g., data processing and monitoring
system). Some type of automated detection software must be used; while
not required, we recommend use of industry standard software (e.g.,
PAMguard, which is open source). Hydrophone signals are processed for
output to the PAM operator with software designed to detect marine
mammal vocalizations. Current PAM technology has some limitations
(e.g., limited directional capabilities and detection range, masking of
signals due to noise from the vessel, source, and/or flow,
localization) and there are no formal guidelines currently in place
regarding specifications for hardware, software, or operator training
requirements.
Our requirement to use PAM refers to the use of calibrated
hydrophone arrays with full system redundancy to detect, identify, and
estimate distance and bearing to vocalizing cetaceans, to the extent
possible. With regard to calibration, the PAM system should have at
least one calibrated hydrophone, sufficient for determining whether
background noise levels on the towed PAM system are sufficiently low to
meet performance expectations. Additionally,
[[Page 63360]]
if multiple hydrophone types occur in a system (i.e., monitor different
bandwidths), then one hydrophone from each such type should be
calibrated, and whenever sets of hydrophones (of the same type) are
sufficiently spatially separated such that they would be expected to
experience ambient noise environments that differ by 6 dB or more
across any integrated species cluster bandwidth, then at least one
hydrophone from each set should be calibrated. The arrays should
incorporate appropriate hydrophone elements (1 Hz to 180 kHz range) and
sound data acquisition card technology for sampling relevant
frequencies (i.e., to 360 kHz). This hardware should be coupled with
appropriate software to aid monitoring and listening by a PAM operator
skilled in bioacoustics analysis and computer system specifications
capable of running appropriate software.
Applicant-specific PAM plans were made available for review either
in individual applications or as separate documents online at:
www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-atlantic. As recommended by
Thode et al. (2017), PAM plans should, at minimum, adequately address
and describe (1) the hardware and software planned for use, including a
hardware performance diagram demonstrating that the sensitivity and
dynamic range of the hardware is appropriate for the operation; (2)
deployment methodology, including target depth/tow distance; (3)
definitions of expected operational conditions, used to summarize
background noise statistics; (4) proposed detection-classification-
localization methodology, including anticipated species clusters (using
a cluster definition table), target minimum detection range for each
cluster, and the proposed localization method for each cluster; (5)
operation plans, including the background noise sampling schedule; (6)
array design considerations for noise abatement; and (7) cluster-
specific details regarding which real-time displays and automated
detectors the operator would monitor.
In coordination with vessel crew, the lead PAM operator will be
responsible for deployment, retrieval, and testing and optimization of
the hydrophone array. While on duty, the PAM operator must diligently
listen to received signals and/or monitoring display screens in order
to detect vocalizing cetaceans, except as required to attend to PAM
equipment. The PAM operator must use appropriate sample analysis and
filtering techniques and, as described below, must report all cetacean
detections. While not required prior to development of formal standards
for PAM use, we recommend that vessel self-noise assessments are
undertaken during mobilization in order to optimize PAM array
configuration according to the specific noise characteristics of the
vessel and equipment involved, and to refine expectations for distance/
bearing estimations for cetacean species during the survey. Copies of
any vessel self-noise assessment reports must be included with the
summary trip report.
Data Collection
PSOs must use standardized data forms, whether hard copy or
electronic. PSOs will record detailed information about any
implementation of mitigation requirements, including the distance of
animals to the acoustic source and description of specific actions that
ensued, the behavior of the animal(s), any observed changes in behavior
before and after implementation of mitigation, and if shutdown was
implemented, the length of time before any subsequent ramp-up of the
acoustic source to resume survey. If required mitigation was not
implemented, PSOs should submit a description of the circumstances. We
require that, at a minimum, the following information be reported:
Vessel names (source vessel and other vessels associated
with survey) and call signs;
PSO names and affiliations;
Dates of departures and returns to port with port name;
Dates and times (Greenwich Mean Time) of survey effort and
times corresponding with PSO effort;
Vessel location (latitude/longitude) when survey effort
begins and ends; vessel location at beginning and end of visual PSO
duty shifts;
Vessel heading and speed at beginning and end of visual
PSO duty shifts and upon any line change;
Environmental conditions while on visual survey (at
beginning and end of PSO shift and whenever conditions change
significantly), including wind speed and direction, Beaufort sea state,
Beaufort wind force, swell height, weather conditions, cloud cover, sun
glare, and overall visibility to the horizon;
Factors that may be contributing to impaired observations
during each PSO shift change or as needed as environmental conditions
change (e.g., vessel traffic, equipment malfunctions);
Survey activity information, such as acoustic source power
output while in operation, number and volume of airguns operating in
the array, tow depth of the array, and any other notes of significance
(i.e., pre-ramp-up survey, ramp-up, shutdown, testing, shooting, ramp-
up completion, end of operations, streamers, etc.);
If a marine mammal is sighted, the following information
should be recorded:
[cir] Watch status (sighting made by PSO on/off effort,
opportunistic, crew, alternate vessel/platform);
[cir] PSO who sighted the animal;
[cir] Time of sighting;
[cir] Vessel location at time of sighting;
[cir] Water depth;
[cir] Direction of vessel's travel (compass direction);
[cir] Direction of animal's travel relative to the vessel;
[cir] Pace of the animal;
[cir] Estimated distance to the animal and its heading relative to
vessel at initial sighting;
[cir] Identification of the animal (e.g., genus/species, lowest
possible taxonomic level, or unidentified); also note the composition
of the group if there is a mix of species;
[cir] Estimated number of animals (high/low/best);
[cir] Estimated number of animals by cohort (adults, yearlings,
juveniles, calves, group composition, etc.);
[cir] Description (as many distinguishing features as possible of
each individual seen, including length, shape, color, pattern, scars or
markings, shape and size of dorsal fin, shape of head, and blow
characteristics);
[cir] Detailed behavior observations (e.g., number of blows, number
of surfaces, breaching, spyhopping, diving, feeding, traveling; as
explicit and detailed as possible; note any observed changes in
behavior);
[cir] Animal's closest point of approach (CPA) and/or closest
distance from the acoustic source;
[cir] Platform activity at time of sighting (e.g., deploying,
recovering, testing, shooting, data acquisition, other); and
[cir] Description of any actions implemented in response to the
sighting (e.g., delays, shutdown, ramp-up, speed or course alteration,
etc.); time and location of the action should also be recorded;
If a marine mammal is detected while using the PAM system,
the following information should be recorded:
[cir] An acoustic encounter identification number, and whether the
detection was linked with a visual sighting;
[cir] Time when first and last heard;
[cir] Types and nature of sounds heard (e.g., clicks, whistles,
creaks, burst pulses, continuous, sporadic, strength of signal, etc.);
and
[[Page 63361]]
[cir] Any additional information recorded such as water depth of
the hydrophone array, bearing of the animal to the vessel (if
determinable), species or taxonomic group (if determinable),
spectrogram screenshot, and any other notable information.
Reporting
Applicants must submit a draft comprehensive report to NMFS within
90 days of the completion of survey effort or expiration of the IHA
(whichever comes first), and must include all information described
above under ``Data Collection.'' If a subsequent IHA request is
planned, a report must be submitted a minimum of 75 days prior to the
requested date of issuance for the subsequent IHA. The report must
describe the operations conducted and sightings of marine mammals near
the operations; provide full documentation of methods, results, and
interpretation pertaining to all monitoring; summarize the dates and
locations of survey operations, and all marine mammal sightings (dates,
times, locations, activities, associated survey activities); and
provide information regarding locations where the acoustic source was
used. The IHA-holder shall provide geo-referenced time-stamped vessel
tracklines for all time periods in which airguns (full array or single)
were operating. Tracklines should include points recording any change
in airgun status (e.g., when the airguns began operating, when they
were turned off). GIS files shall be provided in ESRI shapefile format
and include the UTC date and time, latitude in decimal degrees, and
longitude in decimal degrees. All coordinates should be referenced to
the WGS84 geographic coordinate system. In addition to the report, all
raw observational data shall be made available to NMFS. This report
must also include a validation document concerning the use of PAM,
which should include necessary noise validation diagrams and
demonstrate whether background noise levels on the PAM deployment
limited achievement of the planned detection goals. The draft report
must be accompanied by a certification from the lead PSO as to the
accuracy of the report. A final report must be submitted within 30 days
following resolution of any NMFS comments on the draft report.
In association with the final comprehensive reports, NMFS will
calculate and make available estimates of the number of takes based on
the observations and in consideration of the detectability of the
marine mammal species observed (as described below). PSO effort, survey
details, and sightings data should be recorded continuously during
surveys and reports prepared each day during which survey effort is
conducted. As described below, NMFS will use these observational data
to calculate corrected numbers of marine mammals taken.
There are multiple reasons why marine mammals may be present and
yet be undetected by observers. Animals are missed because they are
underwater (availability bias) or because they are available to be
seen, but are missed by observers (perception and detection biases)
(e.g., Marsh and Sinclair, 1989). Negative bias on perception or
detection of an available animal may result from environmental
conditions, limitations inherent to the observation platform, or
observer ability. In this case, we do not have prior knowledge of any
potential negative bias on detection probability due to observation
platform or observer ability. Therefore, observational data corrections
must be made with respect to assumed species-specific detection
probability as evaluated through consideration of environmental factors
(e.g., f(0)). In order to make these corrections, we plan to use a
method recommended by the Marine Mammal Commission (MMC) for estimating
the number of cetaceans in the vicinity of the surveys based on the
number of groups detected. This method is described in full in the
MMC's comment letter for these actions, which is available online at:
www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-atlantic.
Reporting Injured or Dead Marine Mammals
Discovery of Injured or Dead Marine Mammal--In the event that
personnel involved in the survey activities covered by the
authorization discover an injured or dead marine mammal, the IHA-holder
shall report the incident to the Office of Protected Resources (OPR),
NMFS and to regional stranding coordinators as soon as feasible. The
report must include the following information:
Time, date, and location (latitude/longitude) of the first
discovery (and updated location information if known and applicable);
Species identification (if known) or description of the
animal(s) involved;
Condition of the animal(s) (including carcass condition if
the animal is dead);
Observed behaviors of the animal(s), if alive;
If available, photographs or video footage of the
animal(s); and
General circumstances under which the animal was
discovered.
Vessel Strike--In the event of a ship strike of a marine mammal by
any vessel involved in the activities covered by the authorization, the
IHA-holder shall report the incident to OPR, NMFS and to regional
stranding coordinators as soon as feasible. The report must include the
following information:
Time, date, and location (latitude/longitude) of the
incident;
Species identification (if known) or description of the
animal(s) involved;
Vessel's speed during and leading up to the incident;
Vessel's course/heading and what operations were being
conducted (if applicable);
Status of all sound sources in use;
Description of avoidance measures/requirements that were
in place at the time of the strike and what additional measures were
taken, if any, to avoid strike;
Environmental conditions (e.g., wind speed and direction,
Beaufort sea state, cloud cover, visibility) immediately preceding the
strike;
Estimated size and length of animal that was struck;
Description of the behavior of the marine mammal
immediately preceding and following the strike;
If available, description of the presence and behavior of
any other marine mammals immediately preceding the strike;
Estimated fate of the animal (e.g., dead, injured but
alive, injured and moving, blood or tissue observed in the water,
status unknown, disappeared); and
To the extent practicable, photographs or video footage of
the animal(s).
Actions To Minimize Additional Harm to Live-Stranded (or Milling)
Marine Mammals
In the event of a live stranding (or near-shore atypical milling)
event within 50 km of the survey operations, where the NMFS stranding
network is engaged in herding or other interventions to return animals
to the water, the Director of OPR, NMFS (or designee) will advise the
IHA-holder of the need to implement shutdown procedures for all active
acoustic sources operating within 50 km of the stranding. Shutdown
procedures for live stranding or milling marine mammals include the
following:
If at any time, the marine mammals die or are euthanized,
or if herding/intervention efforts are stopped, the Director of OPR,
NMFS (or designee) will advise the IHA-holder that the
[[Page 63362]]
shutdown around the animals' location is no longer needed.
Otherwise, shutdown procedures will remain in effect until
the Director of OPR, NMFS (or designee) determines and advises the IHA-
holder that all live animals involved have left the area (either of
their own volition or following an intervention).
If further observations of the marine mammals indicate the
potential for re-stranding, additional coordination with the IHA-holder
will be required to determine what measures are necessary to minimize
that likelihood (e.g., extending the shutdown or moving operations
farther away) and to implement those measures as appropriate.
Shutdown procedures are not related to the investigation of the
cause of the stranding and their implementation is not intended to
imply that the specified activity is the cause of the stranding.
Rather, shutdown procedures are intended to protect marine mammals
exhibiting indicators of distress by minimizing their exposure to
possible additional stressors, regardless of the factors that
contributed to the stranding.
Additional Information Requests--If NMFS determines that the
circumstances of any marine mammal stranding found in the vicinity of
the activity suggest investigation of the association with survey
activities is warranted (example circumstances noted below), and an
investigation into the stranding is being pursued, NMFS will submit a
written request to the IHA-holder indicating that the following initial
available information must be provided as soon as possible, but no
later than 7 business days after the request for information.
Status of all sound source use in the 48 hours preceding
the estimated time of stranding and within 50 km of the discovery/
notification of the stranding by NMFS; and
If available, description of the behavior of any marine
mammal(s) observed preceding (i.e., within 48 hours and 50 km) and
immediately after the discovery of the stranding.
Examples of circumstances that could trigger the additional
information request include, but are not limited to, the following:
Atypical nearshore milling events of live cetaceans;
Mass strandings of cetaceans (two or more individuals, not
including cow/calf pairs);
Beaked whale strandings;
Necropsies with findings of pathologies that are unusual
for the species or area; or
Stranded animals with findings consistent with blast
trauma.
In the event that the investigation is still inconclusive, the
investigation of the association of the survey activities is still
warranted, and the investigation is still being pursued, NMFS may
provide additional information requests, in writing, regarding the
nature and location of survey operations prior to the time period
above.
Negligible Impact Analyses and Determinations
NMFS has defined negligible impact as an impact resulting from the
specified activity that cannot be reasonably expected to, and is not
reasonably likely to, adversely affect the species or stock through
effects on annual rates of recruitment or survival (50 CFR 216.103). A
negligible impact finding is based on the lack of likely adverse
effects on annual rates of recruitment or survival (i.e., population-
level effects). An estimate of the number of takes alone is not enough
information on which to base a negligible impact determination. In
addition to considering estimates of the number of marine mammals that
might be ``taken'' by mortality, serious injury, and Level A or Level B
harassment, we consider other factors, such as the type of take, the
likely nature of any behavioral responses (e.g., intensity, duration),
the context of any such responses (e.g., critical reproductive time or
location, migration), as well as effects on habitat, and the likely
effectiveness of mitigation. We also assess the number, intensity, and
context of estimated takes by evaluating this information relative to
population status. Consistent with the 1989 preamble for NMFS's
implementing regulations (54 FR 40338; September 29, 1989), the impacts
from other past and ongoing anthropogenic activities are incorporated
into these analyses via their impacts on the environmental baseline
(e.g., as reflected in the regulatory status of the species, population
size and growth rate where known, ongoing sources of human-caused
mortality).
We first provide a generic description of our approach to the
negligible impact analyses for these actions, which incorporates
elements of the assessment methodology described by Wood et al. (2012),
before providing applicant-specific analysis. For each potential
activity-related stressor, we consider the potential effects to marine
mammals and the likely significance of those effects to the species or
stock as a whole. Potential risk due to vessel collision and related
mitigation measures as well as potential risk due to entanglement and
contaminant spills were addressed under ``Mitigation'' and in the
``Potential Effects of the Specified Activity on Marine Mammals''
section of our Notice of Proposed IHAs and are not discussed further,
as there are minimal risks expected from these potential stressors.
Our analyses incorporate a simple matrix assessment approach to
generate relative impact ratings that couple potential magnitude of
effect on a stock and likely consequences of those effects for
individuals, given biologically relevant information (e.g.,
compensatory ability). These impact ratings are then combined with
consideration of contextual information, such as the status of the
stock or species, in conjunction with our required mitigation strategy,
to ultimately inform our negligible impact determinations. Figure 5
provides an overview of this framework. Elements of this approach are
subjective and relative within the context of these particular actions
and, overall, these analyses necessarily require the application of
professional judgment. As shown in Figure 5, it is important to be
clear that the ``impact rating'' does not equate to the ultimate
assessment of impact to the species or stock, i.e., the negligible
impact determination. The ``impact rating'' is considered in
conjunction with relevant contextual factors to inform the overall
assessment of impact to the species or stock.
Changes From the Notice of Proposed IHAs
Following review of public comments, we largely retain the
negligible impact analysis framework and specific analyses described in
our Notice of Proposed IHAs. However, we have made several adjustments
on the basis of our review.
As a result of our revised take estimates (``Estimated
Take'') and reconsideration of available information (``Description of
Marine Mammals in the Area of the Specified Activities'' and ``Small
Numbers Analyses''), the amount of take has changed for some species
for some applicants. In some cases, this leads to a change in overall
magnitude rating.
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[GRAPHIC] [TIFF OMITTED] TN07DE18.008
We agree with commenters who pointed out that a de minimis
magnitude rating should not render consequences for individuals
irrelevant to the impact rating. Rather, the assessed level of
consequences pairs with the magnitude rating to produce the overall
impact rating. In our preliminary negligible impact analyses, for
example, mysticete whales with a de minimis amount of take were
assigned an overall de minimis impact rating, as consequences were
considered not applicable in cases where a de minimis magnitude rating
was assigned. However, the assessed level of potential consequences for
individual mysticetes of ``medium''--which is related to inherent
vulnerabilities of the taxon, and is therefore not dependent on the
specific magnitude rating--would still exist, regardless of the amount
of take/magnitude rating. Therefore, under our revised approach, a
mysticete whale with a de minimis magnitude rating is now assigned a
low impact rating.
In order to reflect the change described in the preceding
paragraph, we have adjusted the impact rating scheme (Table 9). Whereas
before a de minimis magnitude rating previously resulted in a de
minimis impact rating regardless of assessed potential consequences to
individuals, a de minimis magnitude rating now leads to a de minimis
impact rating only if the assessed consequences are low; the de minimis
impact rating with medium assessed potential consequences for
individuals would lead to an impact rating of low.
Impact Rating
Magnitude--We consider magnitude of effect as a semi-quantitative
evaluation of measurable factors presented as relative ratings that
address the spatiotemporal extent of expected effects to a species or
stock and their habitat. Magnitude ratings are developed as a
combination of measurable factors: The amount of take, the spatial
extent of the effects in the context of the species range, and the
duration of effects.
Amount of Take
We consider authorized take by Level B harassment of less than five
percent of the most appropriate population abundance to be de minimis,
while authorized Level B harassment taking between 5-15 percent is low.
A moderate amount of authorized taking by Level B harassment would be
from 15-25 percent, and high above 25 percent.
Although we do not define quantitative metrics relating to amount
of potential take by Level A harassment, for all applicant companies
the expected potential for Level A harassment and, therefore, the
authorized taking, is very low (Table 6). For these specified
activities, as described in detail in ``Estimated Take,'' the best
available science indicates that there is no reasonable potential for
Level A harassment of mid-frequency cetaceans, while there is only
limited potential for Level A harassment of low-frequency cetaceans
when considering that Level A harassment is dependent on accumulation
of energy from a mobile acoustic source. Similarly, estimated takes by
Level A harassment are very low for all high-frequency cetacean
species.
Overall, while these limited incidents of Level A harassment would
result in
[[Page 63364]]
permanent hearing loss, the effects of such hearing loss are expected
to be minor for several reasons. First, the acoustic thresholds used in
our exposure analysis represent thresholds for the onset of PTS (i.e.,
the minimum sound levels at which minor PTS could occur; NMFS, 2018),
not thresholds for moderate or severe PTS. In order to determine the
likelihood of moderate or severe PTS, one needs to consider the actual
level of exposure (for high-frequency cetaceans) or, for low-frequency
cetaceans, the duration of exposure at the PTS onset threshold
distances from the airgun arrays or closer. High-frequency cetaceans
that may be present (i.e., harbor porpoise and Kogia spp.) are known to
be behaviorally sensitive to acoustic disturbance and are unlikely to
approach source vessels at distances that might lead to more severe
PTS. Similarly, mysticete whales are known to display avoidance
behaviors in the vicinity of airgun surveys (e.g., Ellison et al.,
2016) and, when considered in conjunction with the estimated distances
to the thresholds for the onset of PTS (Table 5), it is likely that
such PTS exposure would be brief and at or near PTS onset levels. For
example, a recent study analyzing 16 years of PSO data consisting of
marine mammal observations during seismic surveys in waters off the
United Kingdom found that the median closest approach by fin whales
during active airgun use was 1,225 m (Stone et al., 2017), a distance
well beyond the PTS onset threshold distances estimated for these
specific airgun arrays. The degree of PTS would be further minimized
through use of the ramp-up procedure, which will alert animals to the
source prior to its achieving full power, and through shutdown
requirements, which will not necessarily prevent exposure but are
expected to reduce the intensity and duration of exposure. Available
data suggest that such PTS would primarily occur at frequencies where
the majority of the energy from airgun sounds occurs (below 500 Hz).
For high-frequency cetaceans, any PTS would therefore occur at
frequencies well outside their estimated range of maximum sensitivity.
For low-frequency cetaceans, these frequencies overlap with the
frequencies used for communication and so may interfere somewhat with
their ability to communicate, though still below the estimated range of
maximum sensitivity for these species. The expected mild PTS would not
likely meaningfully impact the affected high-frequency cetaceans, and
may have minor effects on the ability of affected low-frequency
cetaceans to hear conspecific calls and/or other environmental cues.
For all applicants, the expected effects of Level A harassment on all
stocks to which such take may occur is appropriately considered de
minimis.
Spatial Extent
Spatial extent relates to overlap of the expected range of the
affected stock with the expected footprint of the stressor. While we do
not define quantitative metrics relative to assessment of spatial
extent, a relatively low impact is defined here as a localized effect
on the stock's range, a relatively moderate impact is defined as a
regional-scale effect (meaning that the overlap between stressor and
range was partial), and a relatively high impact is one in which the
degree of overlap between stressor and range is near total. For a
mobile activity occurring over a relatively large, regional-scale area,
this categorization is made largely on the basis of the stock range in
relation to the action area. For example, the harbor porpoise is
expected to occur almost entirely outside of the planned survey areas
(Hayes et al., 2017; Roberts et al., 2016) and therefore despite the
large extent of planned survey activity, the spatial extent of
potential stressor effect would be low. A medium degree of effect would
be expected for a species such as the Risso's dolphin, which has a
distribution in shelf and slope waters along the majority of the U.S.
Atlantic coast, and which also would be expected to have greater
abundance in mid-Atlantic waters north of the survey areas in the
summer (Hayes et al., 2018a; Roberts et al., 2016). This means that the
extent of potential stressor for this species would at all times be
expected to have some overlap with a portion of the stock, while some
portion (increasing in summer and fall months) would at all times be
outside the stressor footprint. A higher degree of impact with regard
to spatial extent would be expected for a species such as the Clymene
dolphin, which is expected to have a generally more southerly
distribution (Waring et al., 2014; Roberts et al., 2016) and thus more
nearly complete overlap with the expected stressor footprint in the
specific geographic region.
In Tables 10-14 below, spatial extent is presented as a range for
certain species with known migratory patterns. We expect spatial extent
(overlap of stock range with planned survey area) to be low for right
whales from May through October but moderate from November through
April, due to right whale movements into southeastern shelf waters in
the winter for calving. The overlap is considered moderate during
winter because not all right whales make this winter migration, and
those that do are largely found in shallow waters where little survey
effort is planned (and when/where we prescribe a spatial restriction
that would largely preclude any potential overlap between right whales
and effects of the survey activities). Spatial extent for humpback
whales is expected to be low for most of the year, but likely moderate
during winter, while spatial extent for minke whales is likely low in
summer, moderate in spring and fall, and high in winter. While we
consider spatial extent to be low year-round for fin whales, their
range overlap with the planned survey area does vary across the seasons
and is closer to moderate in winter and spring. We expect spatial
extent for common dolphins to be lower in fall but generally moderate.
Similarly, we expect spatial extent for Risso's dolphins to be lower in
summer but generally moderate. Although survey plans differ across
applicants, all cover large spatial scales that extend throughout much
of the specific geographic region, and we do not expect meaningful
differences across surveys with regard to spatial extent.
Temporal Extent
The temporal aspect of the stressor is measured through
consideration of duration and frequency. Duration describes how long
the effects of the stressor last. Temporal frequency may range from
continuous to isolated (may occur one or two times), or may be
intermittent. We consider a temporary effect lasting up to one month
(prior to the animal or habitat reverting to a ``normal'' condition) to
be short-term, whereas long[hyphen]term effects are more permanent,
lasting beyond one season (with animals or habitat potentially
reverting to a ``normal'' condition). Moderate[hyphen]term is defined
as between 1-3 months. These metrics and their potential combinations
help to derive the ratings summarized in Table 8. Temporal extent is
not indicated in Tables 10-14 below, as it did not affect the magnitude
rating for any applicant's specified activity.
With regard to the duration of each estimated instance of exposure,
we are unable to produce estimates specific to the specified activities
due to the temporal and spatial uncertainty of vessel and cetacean
movements within the geographic region. However, given the constant
movement of vessels and animals, all exposures are expected to be less
than a single day in duration. For example, based on modeling of
similar activities in the Gulf of Mexico, we
[[Page 63365]]
assume that most instances of exposure would only last for a few
minutes (see Table 26-27 of Zeddies et al., 2015; available online at
www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-mexico), especially in
the case of animals migrating through the immediate vicinity of the
source vessel (e.g., Costa et al., 2016).
Table 8--Magnitude Rating
----------------------------------------------------------------------------------------------------------------
Amount of take Spatial extent Duration and frequency Magnitude rating
----------------------------------------------------------------------------------------------------------------
High.............................. Any.................. Any............................ High.
Any except de minimis............. High................. Any............................ ....................
Moderate.......................... Moderate............. Any except short-term/isolated. ....................
Moderate.......................... Moderate............. Short-term/isolated............ Medium.
Moderate.......................... Low.................. Any............................ ....................
Low............................... Moderate............. Any............................ ....................
Low............................... Low.................. Any except short-term/ ....................
intermittent or isolated.
Low............................... Low.................. Short-term/intermittent or Low.
isolated.
De minimis........................ Any.................. Any............................ De minimis.
----------------------------------------------------------------------------------------------------------------
Adapted from Table 3.4 of Wood et al. (2012).
Consequences--Considerations of amount, extent, and duration give
an understanding of expected magnitude of effect for the stock or
species and their habitat, which is next considered in context of the
likely consequences of those effects for individuals. We consider
likely relative consequences through a qualitative evaluation of
species-specific information that helps predict the consequences of the
information addressed through the magnitude rating, i.e., expected
effects. The likely consequences of a given effect to individuals is
independent of the magnitude of effect, i.e., although we recognize
that the ultimate impact is to some degree scaled to the magnitude of
effect, the extent to which a species is inherently vulnerable to harm
from the effects (and therefore sensitive to magnitude) is captured by
the ``consequences'' factor. This evaluation considers factors
including acoustic sensitivity, communication range, known aspects of
behavior relevant to a consideration of consequences of effects, and
assumed compensatory abilities to engage in important behaviors (e.g.,
breeding, foraging) in alternate areas. The magnitude rating and likely
consequences are combined to produce an ``impact rating'' (Table 9).
For example, if a delphinid species is predicted to have a high
amount of disturbance and over a high degree of spatial extent, that
stock would receive a high magnitude rating for that particular survey.
However, we may then assess that the species may have a high degree of
compensatory ability among individuals; therefore, our conclusion would
be that the consequences of any effects on individuals are likely low.
The overall impact rating in this scenario would be moderate. Table 9
summarizes impact rating scenarios.
Table 9--Impact Rating
------------------------------------------------------------------------
Consequences (for Impact rating (for
Magnitude rating individuals) species or stock)
------------------------------------------------------------------------
High........................ High/medium......... High.
High........................ Low................. Moderate.
Medium...................... High/medium......... ....................
Low......................... High................ ....................
Medium...................... Low................. Low.
Low......................... Medium/low.......... ....................
De minimis.................. Medium.............. ....................
De minimis.................. Low................. De minimis.
------------------------------------------------------------------------
Adapted from Table 3.5 of Wood et al. (2012).
Likely consequences, as presented in Tables 10-14 below, are
considered medium for each species of mysticete whales (low-frequency
hearing specialists), due to the greater potential for masking impacts
at longer ranges than other taxa and at frequencies that overlap a
larger portion of both their hearing and vocalization ranges. Likely
consequences are considered medium for sperm whales due to potential
for survey noise to disrupt foraging activity (e.g., Miller et al.,
2009; Farmer et al., 2018). The likely consequences are considered high
for beaked whales due to the combination of known acoustic sensitivity
and expected residency patterns, as we expect that compensatory ability
for beaked whales will be low due to presumed residency in certain
shelf break and deepwater canyon areas covered by the planned survey
areas. Similarly, Kogia spp. are presumed to be more acoustically
sensitive species, but unlike beaked whales we expect that Kogia spp.
would have a reasonable compensatory ability to perform important
behavior in alternate areas, as they are expected to occur broadly over
the continental slope (e.g., Bloodworth and Odell, 2008)--therefore, we
assume that consequences would be low for Kogia spp. generally.
Consequences are also considered low for harbor porpoise; although they
are considered to be an acoustically sensitive species and potentially
vulnerable to limited instances of auditory injury (as are Kogia spp.),
we have no information to suggest that porpoises are resident within
the specific geographic region or that the expected disturbance events
would significantly impede their ability to engage in critical
behaviors.
[[Page 63366]]
Consequences are considered low for most delphinids, as it is unlikely
that disturbance due to survey noise would entail significant
disruption of normal behavioral patterns, long-term displacement, or
significant potential for masking of acoustic space. However, for pilot
whales we believe likely consequences to be medium due to expected
residency in areas of importance and, therefore, lack of compensatory
ability. Because the nature of the stressor is the same across
applicants, we do not expect meaningful differences with regard to
likely consequences.
Context
In addition to our initial impact ratings, we then also consider
additional relevant contextual factors in a qualitative fashion. This
important consideration of context is applied to a given impact rating
in order to produce a final assessment of impact to the stock or
species, i.e., our negligible impact determinations. Relevant
contextual factors include population status, other stressors
(including impacts on prey and other habitat), and required mitigation.
Here, we reiterate discussion relating to our development of
targeted mitigation measures and note certain contextual factors, which
are applicable to negligible impact analyses for all five applicants.
Applicant-specific analyses are provided later.
We developed mitigation requirements (i.e., time-area
restrictions) designed specifically to provide benefit to certain
species or stocks for which we predict a relatively moderate to high
amount of exposure to survey noise and/or which have contextual factors
that we believe necessitate special consideration. Time-area
restrictions, described in detail in ``Mitigation'' and depicted in
Figures 3-4, are designed specifically to provide benefit to the North
Atlantic right whale, bottlenose dolphin, sperm whale, beaked whales,
and pilot whales. In addition, we expect these areas to provide some
subsidiary benefit to additional species that may be present. In
particular, Area #4 (Figure 4), although delineated in order to
specifically provide an area of anticipated benefit to beaked whales,
sperm whales, and pilot whales, is expected to host a diverse
assemblage of cetacean species. The output of the Roberts et al. (2016)
models, as used in core abundance area analyses (described in detail in
``Mitigation''), indicates that species most likely to derive
subsidiary benefit from this time-area restriction include the
bottlenose dolphin (offshore stock), Risso's dolphin, and common
dolphin. For species with density predicted through stratified models,
core abundance analysis is not possible and assumptions regarding
potential benefit of time-area restrictions are based on known ecology
of the species and sightings patterns and are less robust.
Nevertheless, subsidiary benefit for Areas #1-4 (Figure 4) should be
expected for species known to be present in these areas (e.g., assumed
affinity for shelf/slope/abyss areas off Cape Hatteras): Kogia spp.,
pantropical spotted dolphin, Clymene dolphin, and rough-toothed
dolphin.
These mitigation measures benefit both the primary species for
which they were designed and the species that may benefit secondarily
by reducing impacts to marine mammal habitat and by reducing the
numbers of individuals likely to be exposed to survey noise. For
resident species in areas where seasonal closures are required, we also
expect reduction in the numbers of times that individuals are exposed
to survey noise (also discussed in ``Small Numbers Analyses,'' below).
Perhaps of greater importance, we expect that these restrictions will
reduce disturbance of these species in the places most important to
them for critical behaviors such as foraging and socialization. Area #1
(Figure 4), which is a year-round closure, is assumed to be an area
important for beaked whale foraging, while Areas #2-3 (also year-round
closures) are assumed to provide important foraging opportunities for
sperm whales as well as beaked whales. Area #4, a seasonal closure, is
comprised of shelf-edge habitat where beaked whales and pilot whales
are believed to be year-round residents as well as slope and abyss
habitat predicted to contain high abundance of sperm whales during the
period of closure. Further detail regarding rationale for these
closures is provided under ``Mitigation.''
The North Atlantic right whale, sei whale, fin whale, blue
whale, and sperm whale are listed as endangered under the Endangered
Species Act, and all coastal stocks of bottlenose dolphin are
designated as depleted under the MMPA (and have recently experienced an
Unusual Mortality Event, described earlier in this document). However,
sei whales and blue whales are unlikely to be meaningfully impacted by
the specified activities (see ``Rare Species'' below). All four
mysticete species are also classified as endangered (i.e., ``considered
to be facing a very high risk of extinction in the wild'') on the
International Union for Conservation of Nature Red List of Threatened
Species, whereas the sperm whale is classified as vulnerable (i.e.,
``considered to be facing a high risk of extinction in the wild'')
(IUCN, 2017). Our required mitigation is designed to avoid impacts to
the right whale and to depleted stocks of bottlenose dolphin. Survey
activities must avoid all areas where the right whale and coastal
stocks of bottlenose dolphin are reasonably expected to occur (or, for
the right whale, comparable protection would be achieved through
implementation of a NMFS-approved mitigation and monitoring plan at
distances between 47-80 km offshore; see ``Mitigation''), and we
require shutdown of the acoustic source upon observation of any right
whale at extended distance compared with the standard shutdown
requirement. If the observed right whale is within the behavioral
harassment zone, it would still be considered taken, but by immediately
shutting down the acoustic source the duration of harassment is
minimized and the significance of the harassment event reduced as much
as possible.
Although listed as endangered, the primary threat faced by the
sperm whale (i.e., commercial whaling) has been eliminated and,
further, sperm whales in the western North Atlantic were little
affected by modern whaling (Taylor et al., 2008). Current potential
threats to the species globally include vessel strikes, entanglement in
fishing gear, anthropogenic noise, exposure to contaminants, climate
change, and marine debris. However, for the North Atlantic stock, the
most recent estimate of annual human-caused mortality and serious
injury (M/SI) is 22 percent of the potential biological removal (PBR)
level for the stock. As described previously, PBR is defined as ``the
maximum number of animals, not including natural mortalities, that may
be removed from a marine mammal stock while allowing that stock to
reach or maintain its optimum sustainable population.'' For depleted
stocks, levels of human-caused mortality and serious injury exceeding
the PBR level are likely to delay restoration of the stock to OSP level
by more than ten percent in comparison with recovery time in the
absence of human-caused M/SI.
The most recent status review for the species stated that existing
regulatory mechanisms appear to minimize threats to sperm whales and
that, despite uncertainty regarding threats such as climate change,
contaminants, and anthropogenic noise, the significance of threat
facing the species should be considered low to moderate (NMFS, 2015b).
Nevertheless, existing empirical data (e.g., Miller et al., 2009;
Farmer et al., 2018) highlight the potential for seismic survey
activity to negatively
[[Page 63367]]
impact foraging behavior of sperm whales. In consideration of this
likelihood, the species status, and the relatively high amount of
predicted exposures to survey noise, we have given special
consideration to mitigation focused on sperm whales and have defined
time-area restrictions (see ``Mitigation'' and Figure 4) specifically
designed to reduce such impacts on sperm whales in areas expected to be
of greatest importance (i.e., slope habitat and deepwater canyons).
Although the primary direct threat to fin whales was addressed
through the moratorium on commercial whaling, vessel strike and
entanglement in commercial fishing gear remain as substantial direct
threats for the species in the western North Atlantic. As noted below,
the most recent estimate of annual average human-caused mortality for
the fin whale in U.S. waters is equal to the PBR value (Table 2). In
addition, mysticete whales are particularly sensitive to sound in the
frequency range output from use of airgun arrays (e.g., NMFS, 2018).
However, there is conflicting evidence regarding the degree to which
this sound source may significantly disrupt the behavior of mysticete
whales. Generally speaking, mysticete whales have been observed to
react to seismic vessels but have also been observed continuing normal
behavior in the presence of seismic vessels, and behavioral context at
the time of acoustic exposure may be influential in the degree to which
whales display significant behavioral reactions. In addition, while
Edwards et al. (2015) found that fin whales were likely present in all
seasons in U.S. waters north of 35[deg] N, most important habitat areas
are not expected to occur in the planned survey areas. Primary feeding
areas are outside the project area in the Gulf of Maine and off Long
Island (LaBrecque et al., 2015) and, while Hain et al. (1992) suggested
that calving occurs during winter in the mid-Atlantic, Hayes et al.
(2017) state that it is unknown where calving, mating, and wintering
occur for most of the population. Further, fin whales are not
considered to engage in regular mass movements along well-defined
migratory corridors (NMFS, 2010b). The models described by Roberts et
al. (2016), which predicted density at a monthly time step, suggest an
expectation that, while fin whales may be present year-round in shelf
and slope waters north of Cape Hatteras, the large majority of
predicted abundance in U.S. waters would be found outside the planned
survey areas to the north. Very few fin whales are likely present in
the planned survey areas in summer months. Therefore, we have
determined that development of time-area restriction specific to fin
whales is not warranted. However, fin whales present along the shelf
break north of Cape Hatteras during the closure period associated with
Area #4 (Figure 4) would be expected to benefit from the time-area
restriction designed primarily to benefit pilot whales, beaked whales,
and sperm whales.
Critical habitat is designated only for the North Atlantic
right whale, and there are no biologically important areas (BIA)
described within the region (other than for the right whale, and the
described BIA is similar to designated critical habitat). Our required
mitigation is designed to avoid impacts to important habitat for the
North Atlantic right whale (or achieve comparable protection through
implementation of a NMFS-approved mitigation and monitoring plan at
distances between 47-80 km offshore; see ``Mitigation'').
High levels of average annual human-caused M/SI
(approaching or exceeding the PBR level) are ongoing for the North
Atlantic right whale, sei whale, fin whale, and for both long-finned
and short-finned pilot whales (see Table 2). Average annual M/SI is
considered unknown for the blue whale and the false killer whale (PBR
is undetermined for a number of other species (Table 2), but average
annual human-caused M/SI is zero for all of these). Separately, there
are ongoing UMEs for humpback whales and minke whales (as well as for
the right whale), as discussed previously in this notice. Although
threats are considered poorly known for North Atlantic blue whales, PBR
is less than one and ship strike is a known cause of mortality for all
mysticete whales. The most recent record of ship strike mortality for a
blue whale in the U.S. EEZ is from 1998 (Waring et al., 2010). False
killer whales also have a low PBR value (2.1), and may be susceptible
to mortality in commercial fisheries. One false killer whale was
reported as entangled in the pelagic longline fishery in 2011, but was
released alive and not seriously injured. Separately, a stranded false
killer whale in 2009 was classified as due to a fishery interaction.
Incidental take of the sei whale, blue whale, false killer whale, and
long-finned pilot whale is considered unlikely and we authorize take by
behavioral harassment only for a single group of each of the first
three species as a precaution. Although long-finned pilot whales are
unlikely to occur in the action area in significant numbers, the
density models that inform our exposure estimates consider pilot whales
as a guild. It is important to note that our discussion of M/SI in
relation to PBR values provides necessary contextual information
related to the status of stocks; we do not equate harassment with M/SI.
We addressed our consideration of specific mitigation efforts for
the right whale and fin whale above. For minke whales, although the
ongoing UME is under investigation (as occurs for all UMEs), this event
does not provide cause for concern regarding population-level impacts,
as the likely population abundance is greater than 20,000 whales. Even
though the PBR value is based on an abundance for U.S. waters that is
negatively biased and a small fraction of the true population
abundance, annual M/SI does not exceed the calculated PBR value for
minke whales.
With regard to humpback whales, the UME does not yet provide cause
for concern regarding population-level impacts. Despite the UME, the
relevant population of humpback whales (the West Indies breeding
population, or distinct population segment (DPS)) remains healthy.
Prior to 2016, humpback whales were listed under the ESA as an
endangered species worldwide. Following a 2015 global status review
(Bettridge et al., 2015), NMFS established 14 DPSs with different
listing statuses (81 FR 62259; September 8, 2016) pursuant to the ESA.
The West Indies DPS, which consists of the whales whose breeding range
includes the Atlantic margin of the Antilles from Cuba to northern
Venezuela, and whose feeding range primarily includes the Gulf of
Maine, eastern Canada, and western Greenland, was delisted. The status
review identified harmful algal blooms, vessel collisions, and fishing
gear entanglements as relevant threats for this DPS, but noted that all
other threats are considered likely to have no or minor impact on
population size or the growth rate of this DPS (Bettridge et al.,
2015). As described in Bettridge et al. (2015), the West Indies DPS has
a substantial population size (i.e., approximately 10,000; Stevick et
al., 2003; Smith et al., 1999; Bettridge et al., 2015), and appears to
be experiencing consistent growth.
In response to this population context concern for pilot whales, in
conjunction with relatively medium to high amount of predicted
exposures to survey noise for pilot whales, we have given special
consideration to mitigation focused on pilot whales and have defined
time-area restrictions (see ``Mitigation'' and Figure 4) specifically
designed to reduce such impacts on pilot whales in areas
[[Page 63368]]
expected to be of greatest importance (i.e., shelf edge north of Cape
Hatteras).
Beaked whales are considered to be particularly
acoustically sensitive (e.g., Tyack et al., 2011; DeRuiter et al.,
2013; Stimpert et al., 2014; Miller et al., 2015). Considering this
sensitivity in conjunction with the relatively high amount of predicted
exposures to survey noise, we have given special consideration to
mitigation focused on beaked whales and have defined time-area
restrictions (see ``Mitigation'' and Figure 4) specifically designed to
reduce such impacts on beaked whales in areas expected to be of
greatest importance (i.e., shelf edge south of Cape Hatteras and
deepwater canyon areas).
Given the current declining population status of North
Atlantic right whales, it is important to understand the likely
demographics of the expected taking. Therefore, we obtained data from
the North Atlantic Right Whale Consortium Database (pers. comm., T.A.
Gowan to E. Patterson, November 8, 2017), consisting of standardized
sighting records of right whales from 2005 to 2013 from South Carolina
to Florida. Because of the low total number of expected exposure for
right whales, we could not reasonably apply this information on an
applicant-specific basis and therefore present these findings for the
total expected taking across all applicants. Based on this information,
of the total 23 takes of North Atlantic right whales (now revised
downward to 19 takes on the basis of Spectrum's modified survey plan;
see ``Spectrum Survey Plan Modification''), it should be expected that
four exposures could be of adult females with calves, two of adult
females without calves, five of adult males, 11 of juveniles of either
sex, three of calves of either sex, one of an adult of unknown sex, and
two of animals of unknown age and sex. It is important to note that age
class estimates sum to greater than the originally expected total of 23
due to conservative rounding up in presenting the maximum number of
each age-sex class that might be exposed; this should not be construed
as an assumption that there would be more total takes of right whales
than are authorized across all applicants. Each of these exposures
represents a single instance of Level B harassment and is therefore not
considered as a meaningful impact to individuals that could lead to
population-level impacts.
Rare Species
As described previously, there are multiple species that should be
considered rare in the survey areas and for which we authorize only
nominal and precautionary take of a single group for each applicant
survey. Specific to each of the five applicant companies, we do not
expect meaningful impacts to these species (i.e., sei whale, Bryde's
whale, blue whale, killer whale, false killer whale, pygmy killer
whale, melon-headed whale, northern bottlenose whale, spinner dolphin,
Fraser's dolphin, Atlantic white-sided dolphin) and find that the take
from each of the specified activities will have a negligible impact on
these marine mammal species. We do not discuss these 11 species further
in these analyses.
Spectrum
Spectrum originally planned a 165-day survey program, or 45 percent
of the year (approximately two seasons). The original survey plan would
cover a large spatial extent (i.e., a majority of the mid- and south
Atlantic; see Figure 1 of Spectrum's application). Therefore, although
that survey would be long-term (i.e., greater than one season) in total
duration, we would not expect the duration of effect to be greater than
moderate and intermittent in any given area. Table 10 displays relevant
information leading to impact ratings for each species resulting from
Spectrum's original survey plan. In general, we note that although the
temporal and spatial scale of the planned survey activity is large, it
is not occupying the spatial extent all at one time. The fact that this
mobile acoustic source would be moving across large areas (as compared
with geophysical surveys with different objectives that may require
focused effort over long periods of time in smaller areas) means that
more individuals may receive limited exposure to survey noise, versus
fewer individuals receiving more intense exposure and/or for longer
periods of time. The nature of such potentially transitory exposure
(which we nevertheless assume here is of moderate duration and
intermittent, versus isolated) means that the potential significance of
behavioral disruption and potential for longer-term avoidance of
important areas is limited. Please see ``Spectrum Survey Plan
Modification,'' below, for additional information describing the
modified survey plan, findings made in context of the analysis
presented below, and authorized take for Spectrum (Table 17).
Table 10--Magnitude and Impact Ratings, Spectrum
--------------------------------------------------------------------------------------------------------------------------------------------------------
Species Amount Spatial extent Magnitude rating Consequences Impact rating \1\
--------------------------------------------------------------------------------------------------------------------------------------------------------
North Atlantic right whale......... De minimis............ Low-Moderate.......... De minimis........... Medium............... Low.
Humpback whale..................... De minimis............ Low-Moderate.......... De minimis........... Medium............... Low.
Minke whale........................ De minimis............ Low-High.............. De minimis........... Medium............... Low.
Fin whale.......................... Low................... Low................... Medium............... Medium............... Moderate.
Sperm whale........................ Low................... Moderate.............. Medium............... Medium............... Moderate.
Kogia spp.......................... Low................... High.................. High................. Low.................. Moderate.
Beaked whales...................... Low................... Moderate.............. Medium............... High................. Moderate.
Rough-toothed dolphin.............. Moderate.............. High.................. High................. Low.................. Moderate.
Bottlenose dolphin................. High.................. High.................. High................. Low.................. Moderate.
Clymene dolphin.................... High.................. High.................. High................. Low.................. Moderate.
Atlantic spotted dolphin........... Moderate.............. Moderate.............. High................. Low.................. Moderate.
Pantropical spotted dolphin........ Moderate.............. High.................. High................. Low.................. Moderate.
Striped dolphin.................... Low................... Low................... Medium............... Low.................. Low.
Common dolphin..................... Low................... Low-moderate.......... Medium............... Low.................. Low.
Risso's dolphin.................... De minimis............ Low-moderate.......... De minimis........... Low.................. De minimus.
Pilot whales....................... Low................... Moderate.............. Medium............... Medium............... Moderate.
Harbor porpoise.................... De minimis............ Low................... De minimis........... Low.................. De minimis.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Impact rating does not indicate whether overall impact to the species or stock is negligible, but is considered with relevant contextual factors
(described generally above and specifically below) in order to ultimately determine whether the effects of the specified activity on the affected
species or stock are negligible.
[[Page 63369]]
The North Atlantic right whale is endangered, has a very low
population size, and faces significant additional stressors. Therefore,
regardless of even a low impact rating, we believe that the required
mitigation described previously is critically important in order for us
to make the necessary finding and it is with consideration of this
mitigation that we find the take from Spectrum's survey activities will
have a negligible impact on the North Atlantic right whale. The fin
whale receives a moderate impact rating overall, but we expect that for
two seasons (summer and fall) almost no fin whales will be present in
the survey area. For the remainder of the year, it is likely that less
than one quarter of the population will be present within the survey
area (Roberts et al., 2016), meaning that despite medium rankings for
magnitude and likely consequences, these impacts would be experienced
by only a small subset of the overall population. In consideration of
the moderate impact rating, the likely proportion of the population
that may be affected by the specified activities, and the lack of
evidence that the survey area is host to important behaviors that may
be disrupted, we find the take from Spectrum's survey activities will
have a negligible impact on the fin whale.
Magnitude ratings for the sperm whale and beaked whales are medium;
however, consequence factors are medium and high, respectively.
Magnitude rating for pilot whales is medium, but similar to beaked
whales, we expect that compensatory ability will be low (high
consequence rating) due to presumed residency in areas targeted by the
planned survey. These factors lead to moderate impact ratings for all
three species/species groups. However, regardless of impact rating, the
consideration of likely consequences and contextual factors for all
three taxa leads us to conclude that targeted mitigation is important
to support a finding that the effects of the survey will have a
negligible impact on these species. As described previously, sperm
whales are an endangered species with particular susceptibility to
disruption of foraging behavior, beaked whales are particularly
acoustically sensitive (with presumed low compensatory ability), and
pilot whales are sensitive to additional stressors due to a high degree
of mortality in commercial fisheries (and also with low compensatory
ability). Finally, due to their acoustic sensitivity, we require
shutdown of the acoustic source upon detection of a beaked whale at
extended distance from the source vessel. In consideration of the
required mitigation, we find the take from Spectrum's survey activities
will have a negligible impact on the sperm whale, beaked whales (i.e.,
Ziphius cavirostris and Mesoplodon spp.), and pilot whales (i.e.,
Globicephala spp.).
Kogia spp. receive a moderate impact rating. However, although NMFS
does not currently identify a trend for these populations, recent
survey effort and stranding data show a simultaneous increase in at-sea
abundance and strandings, suggesting growing Kogia spp. abundance
(NMFS, 2011; 2013a; Waring et al., 2007; 2013). Finally, we expect that
Kogia spp. will receive subsidiary benefit from the required mitigation
targeted for sperm whales, beaked whales, and pilot whales and,
although minimally effective due to the difficulty of at-sea
observation of Kogia spp., we require shutdown of the acoustic source
upon observation of Kogia spp. at extended distance from the source
vessel. In consideration of these factors--likely population increase
and required mitigation--we find the take from Spectrum's survey
activities will have a negligible impact on Kogia spp.
As described in the introduction to this analysis, it is assumed
that likely consequences are somewhat higher for species of mysticete
whales (low-frequency hearing specialists) due to the greater potential
for masking impacts at longer ranges than other taxa and at frequencies
that overlap a larger portion of both their hearing and vocalization
ranges. Therefore, despite de minimis magnitude ratings, we expect some
consequences to individual humpback and minke whales, i.e., leading to
a low impact rating. However, given the minimal amount of interaction
expected between these species and the survey activities, and in
consideration of the overall low impact ratings, we find the take from
Spectrum's planned survey activities will have a negligible impact on
the humpback whale and minke whale.
Despite medium to high magnitude ratings, remaining delphinid
species receive low to moderate impact ratings due to low consequences
rating relating to a lack of propensity for behavioral disruption due
to airgun survey activity and our expectation that these species would
generally have relatively high compensatory ability. In addition,
contextually these species do not have significant issues relating to
population status or context. Many oceanic delphinid species are
generally more associated with dynamic oceanographic characteristics
rather than static physical features, and those species (such as common
dolphin) with substantial distribution to the north of the survey area
would likely be little affected at the population level by the
activity. For example, both species of spotted dolphin and the offshore
stock of bottlenose dolphin range widely over slope and abyssal waters
(e.g., Waring et al., 2014; Hayes et al., 2017; Roberts et al., 2016),
while the rough-toothed dolphin does not appear bound by water depth in
its range (Ritter, 2002; Wells et al., 2008). Our required mitigation
largely eliminates potential effects to depleted coastal stocks of
bottlenose dolphin. We also expect that meaningful subsidiary benefit
will accrue to certain species from the mitigation targeted for sperm
whales, beaked whales, and pilot whales, most notably to species
presumed to have greater association with shelf break waters north of
Cape Hatteras (e.g., offshore bottlenose dolphins, common dolphins, and
Risso's dolphins). In consideration of these factors--overall impact
ratings and context including required mitigation--we find the take
from Spectrum's planned survey activities will have a negligible impact
on remaining delphinid species (i.e., all stocks of bottlenose dolphin,
two species of spotted dolphin, rough-toothed dolphin, striped dolphin,
common dolphin, and Clymene dolphin).
For those species with de minimis impact ratings we believe that,
absent additional relevant concerns related to population status or
context, the rating implies that a negligible impact should be expected
as a result of the specified activity. No such concerns exist for these
species, and we find the take from Spectrum's survey activities will
have a negligible impact on the Risso's dolphin and harbor porpoise.
In summary, based on the analysis contained herein of the likely
effects of the specified activity on marine mammals and their habitat,
and taking into consideration the implementation of the required
monitoring and mitigation measures, we find that the total marine
mammal take from Spectrum's survey activities will have a negligible
impact on all affected marine mammal species or stocks.
TGS--TGS has planned a 308-day survey program, or 84 percent of the
year (slightly more than three seasons). However, the planned survey
would cover a large spatial extent (i.e., a majority of the mid- and
south Atlantic; see Figures 1-1 to 1-4 of TGS's application).
Therefore, although the survey would be long-term (i.e., greater than
one season) in total duration, we would not expect the duration of
effect to be greater than moderate and intermittent in any given area.
We note
[[Page 63370]]
that TGS plans to deploy two independent source vessels, which would in
effect increase the spatial extent of survey noise at any one time but,
because the vessels would not be operating within the same area or
reshooting lines already covered, this would not be expected to
increase the duration or frequency of exposure experienced by
individual animals. Table 11 displays relevant information leading to
impact ratings for each species resulting from TGS's survey. In
general, we note that although the temporal and spatial scale of the
planned survey activity is large, the fact that these mobile acoustic
sources would be moving across large areas (as compared with
geophysical surveys with different objectives that may require focused
effort over long periods of time in smaller areas) means that more
individuals may receive limited exposure to survey noise, versus fewer
individuals receiving more intense exposure and/or for longer periods
of time. The nature of such potentially transitory exposure (which we
nevertheless assume here is of moderate duration and intermittent,
versus isolated) means that the potential significance of behavioral
disruption and potential for longer-term avoidance of important areas
is limited.
Table 11--Magnitude and Impact Ratings, TGS
--------------------------------------------------------------------------------------------------------------------------------------------------------
Species Amount Spatial extent Magnitude rating Consequences Impact rating \1\
--------------------------------------------------------------------------------------------------------------------------------------------------------
North Atlantic right whale......... De minimis............ Low-Moderate.......... De minimis........... Medium............... Low.
Humpback whale..................... De minimis............ Low-Moderate.......... De minimis........... Medium............... Low.
Minke whale........................ De minimis............ Low-High.............. De minimis........... Medium............... Low.
Fin whale.......................... Moderate.............. Low................... Medium............... Medium............... Moderate.
Sperm whale........................ High.................. Moderate.............. High................. Medium............... High.
Kogia spp.......................... High.................. High.................. High................. Low.................. Moderate.
Beaked whales...................... High.................. Moderate.............. High................. High................. High.
Rough-toothed dolphin.............. High.................. High.................. High................. Low.................. Moderate.
Bottlenose dolphin................. High.................. High.................. High................. Low.................. Moderate.
Clymene dolphin.................... De minimis............ High.................. De minimis........... Low.................. De minimis.
Atlantic spotted dolphin........... High.................. Moderate.............. High................. Low.................. Moderate.
Pantropical spotted dolphin........ Moderate.............. High.................. High................. Low.................. Moderate.
Striped dolphin.................... Low................... Low................... Medium............... Low.................. Low.
Common dolphin..................... High.................. Low-moderate.......... High................. Low.................. Moderate.
Risso's dolphin.................... Moderate.............. Low-moderate.......... High................. Low.................. Moderate.
Pilot whales....................... High.................. Moderate.............. High................. Medium............... High.
Harbor porpoise.................... De minimis............ Low................... De minimis........... Low.................. De minimis.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Impact rating does not indicate whether overall impact to the species or stock is negligible, but is considered with relevant contextual factors
(described generally above and specifically below) in order to ultimately determine whether the effects of the specified activity on the affected
species or stock are negligible.
The North Atlantic right whale is endangered, has a very low
population size, and faces significant additional stressors. Therefore,
regardless of even a low impact rating, we believe that the required
mitigation described previously is critically important in order for us
to make the necessary finding and it is with consideration of this
mitigation that we find the take from TGS's survey activities will have
a negligible impact on the North Atlantic right whale. The fin whale
receives a moderate impact rating overall, but we expect that for two
seasons (summer and fall) almost no fin whales will be present in the
survey area. For the remainder of the year, it is likely that less than
one quarter of the population will be present within the survey area
(Roberts et al., 2016), meaning that despite medium rankings for
magnitude and likely consequences, these impacts would be experienced
by only a small subset of the overall population. In consideration of
the moderate impact rating, the likely proportion of the population
that may be affected by the specified activities, and the lack of
evidence that the survey area is host to important behaviors that may
be disrupted, we find the take from TGS's survey activities will have a
negligible impact on the fin whale.
Magnitude ratings for the sperm whale, beaked whales, and pilot
whales are high and, further, consequence factors reinforce high impact
ratings for all three. In addition, the consideration of likely
consequences and contextual factors leads us to conclude that targeted
mitigation is important to support a finding that the effects of the
survey will have a negligible impact on these species. As described
previously, sperm whales are an endangered species with particular
susceptibility to disruption of foraging behavior, beaked whales are
particularly acoustically sensitive (with presumed low compensatory
ability and, therefore, high consequence rating), and pilot whales are
sensitive to additional stressors due to a high degree of mortality in
commercial fisheries (and also with low compensatory ability). Finally,
due to their acoustic sensitivity, we have required shutdown of the
acoustic source upon observation of a beaked whale at extended distance
from the source vessel. In consideration of the required mitigation, we
find the take from TGS's survey activities will have a negligible
impact on the sperm whale, beaked whales (i.e., Ziphius cavirostris and
Mesoplodon spp.), and pilot whales (i.e., Globicephala spp.).
Kogia spp. receive a moderate impact rating. However, although NMFS
does not currently identify a trend for these populations, recent
survey effort and stranding data show a simultaneous increase in at-sea
abundance and strandings, suggesting growing Kogia spp. abundance
(NMFS, 2011; 2013a; Waring et al., 2007; 2013). Finally, we expect that
Kogia spp. will receive subsidiary benefit from the mitigation targeted
for sperm whales, beaked whales, and pilot whales and, although
minimally effective due to the difficulty of at-sea observation of
Kogia spp., we have required shutdown of the acoustic source upon
observation of Kogia spp. at extended distance from the source vessel.
In consideration of these factors--likely population increase and
required mitigation--we find the take from TGS's survey activities will
have a negligible impact on Kogia spp.
As described in the introduction to this analysis, it is assumed
that likely consequences are somewhat higher for
[[Page 63371]]
species of mysticete whales (low-frequency hearing specialists) due to
the greater potential for masking impacts at longer ranges than other
taxa and at frequencies that overlap a larger portion of both their
hearing and vocalization ranges. Therefore, despite de minimis
magnitude ratings, we expect some consequences to individual humpback
and minke whales, i.e., leading to a low impact rating. However, given
the minimal amount of interaction expected between these species and
the survey activities, and in consideration of the overall low impact
ratings, we find the take from TGS's planned survey activities will
have a negligible impact on the humpback whale and minke whale.
Despite high magnitude ratings, most remaining delphinid species
receive moderate impact ratings (with the exception of the striped
dolphin, with medium magnitude rating and low impact rating), due to
low consequences rating relating to a lack of propensity for behavioral
disruption due to airgun survey activity and our expectation that these
species would generally have relatively high compensatory ability. In
addition, contextually these species do not have significant issues
relating to population status or context. Many oceanic delphinid
species are generally more associated with dynamic oceanographic
characteristics rather than static physical features, and those species
(such as common dolphin) with substantial distribution to the north of
the survey area would likely be little affected at the population level
by the specified activity. For example, both species of spotted dolphin
and the offshore stock of bottlenose dolphin range widely over slope
and abyssal waters (e.g., Waring et al., 2014; Hayes et al., 2017;
Roberts et al., 2016), while the rough-toothed dolphin does not appear
bound by water depth in its range (Ritter, 2002; Wells et al., 2008).
Our required mitigation largely eliminates potential effects to
depleted coastal stocks of bottlenose dolphin. We also expect that
meaningful subsidiary benefit will accrue to certain species from the
mitigation targeted for sperm whales, beaked whales, and pilot whales,
most notably to species presumed to have greater association with shelf
break waters north of Cape Hatteras (e.g., offshore bottlenose
dolphins, common dolphins, and Risso's dolphins). In consideration of
these factors--overall impact ratings and context including required
mitigation--we find the take from TGS's survey activities will have a
negligible impact on most remaining delphinid species (i.e., all stocks
of bottlenose dolphin, two species of spotted dolphin, rough-toothed
dolphin, striped dolphin, common dolphin, and Risso's dolphin).
For those species with de minimis impact ratings we believe that,
absent additional relevant concerns related to population status or
context, the rating implies that a negligible impact should be expected
as a result of the specified activity. No such concerns exist for these
species, and we find the take from TGS's survey activities will have a
negligible impact on the Clymene dolphin and harbor porpoise.
In summary, based on the analysis contained herein of the likely
effects of the specified activity on marine mammals and their habitat,
and taking into consideration the implementation of the required
monitoring and mitigation measures, we find that the total marine
mammal take from TGS's survey activities will have a negligible impact
on all affected marine mammal species or stocks.
ION--ION has planned a 70-day survey program, or 19 percent of the
year (slightly less than one season). However, the planned survey would
cover a large spatial extent (i.e., a majority of the mid- and south
Atlantic; see Figure 1 of ION's application). Therefore, although the
survey would be moderate-term (i.e., from 1-3 months) in total
duration, we would not expect the duration of effect to be greater than
short and isolated to intermittent in any given area. Table 12 displays
relevant information leading to impact ratings for each species
resulting from ION's survey. In general, we note that although the
temporal and spatial scale of the planned survey activity is large, the
fact that this mobile acoustic source would be moving across large
areas (as compared with geophysical surveys with different objectives
that may require focused effort over long periods of time in smaller
areas) means that more individuals may receive limited exposure to
survey noise, versus fewer individuals receiving more intense exposure
and/or for longer periods of time. The nature of such potentially
transitory exposure means that the potential significance of behavioral
disruption and potential for longer-term avoidance of important areas
is limited.
Table 12--Magnitude and Impact Ratings, ION
--------------------------------------------------------------------------------------------------------------------------------------------------------
Species Amount Spatial extent Magnitude rating Consequences Impact rating \1\
--------------------------------------------------------------------------------------------------------------------------------------------------------
North Atlantic right whale......... De minimis............ Low-Moderate.......... De minimis........... Medium............... Low.
Humpback whale..................... De minimis............ Low-Moderate.......... De minimis........... Medium............... Low.
Minke whale........................ De minimis............ Low-High.............. De minimis........... Medium............... Low.
Fin whale.......................... De minimis............ Low................... De minimis........... Medium............... Low.
Sperm whale........................ De minimis............ Moderate.............. De minimis........... Medium............... Low.
Kogia spp.......................... De minimis............ High.................. De minimis........... Low.................. De minimis.
Beaked whales...................... De minimis............ Moderate.............. De minimis........... High................. Low.
Rough-toothed dolphin.............. De minimis............ High.................. De minimis........... Low.................. De minimis.
Bottlenose dolphin................. De minimis............ High.................. De minimis........... Low.................. De minimis.
Clymene dolphin.................... De minimis............ High.................. De minimis........... Low.................. De minimis.
Atlantic spotted dolphin........... De minimis............ Moderate.............. De minimis........... Low.................. De minimis.
Pantropical spotted dolphin........ De minimis............ High.................. De minimis........... Low.................. De minimis.
Striped dolphin.................... De minimis............ Low................... De minimis........... Low.................. De minimis.
Common dolphin..................... De minimis............ Low-moderate.......... De minimis........... Low.................. De minimis.
Risso's dolphin.................... De minimis............ Low-moderate.......... De minimis........... Low.................. De minimis.
Pilot whales....................... De minimis............ Moderate.............. De minimis........... Medium............... Low.
Harbor porpoise.................... De minimis............ Low................... De minimis........... Low.................. De minimis.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Impact rating does not indicate whether overall impact to the species or stock is negligible, but is considered with relevant contextual factors
(described generally above and specifically below) in order to ultimately determine whether the effects of the specified activity on the affected
species or stock are negligible.
[[Page 63372]]
The North Atlantic right whale is endangered, has a very low
population size, and faces significant additional stressors. Therefore,
regardless of impact rating, we believe that the required mitigation
described previously is critically important in order for us to make
the necessary finding and it is with consideration of this mitigation
that we find the take from ION's planned survey activities will have a
negligible impact on the North Atlantic right whale.
Also regardless of impact rating, consideration of assumed
behavioral susceptibility and lack of compensatory ability (i.e.,
consequence factors) as well as additional contextual factors leads us
to conclude that the required targeted time-area mitigation described
previously is important to support a finding that the effects of the
planned survey will have a negligible impact for the sperm whale,
beaked whales (i.e., Ziphius cavirostris and Mesoplodon spp.), and
pilot whales (i.e., Globicephala spp.). As described previously, sperm
whales are an endangered species with particular susceptibility to
disruption of foraging behavior, beaked whales are particularly
acoustically sensitive, and pilot whales are sensitive to additional
stressors due to a high degree of mortality in commercial fisheries.
Further, we expect that compensatory ability for beaked whales will be
low due to presumed residency in certain shelf break and deepwater
canyon areas covered by the survey area and that compensatory ability
for pilot whales will also be low due to presumed residency in areas
targeted by the planned survey (when compensatory ability is assumed to
be low, we assign a high consequence factor). Kogia spp. are also
considered to have heightened acoustic sensitivity and therefore we
have required shutdown of the acoustic source upon observation of a
beaked whale or a Kogia spp. at extended distance from the source
vessel. In consideration of the required mitigation, we find the take
from ION's survey activities will have a negligible impact on the sperm
whale, beaked whales, pilot whales, and Kogia spp.
As described in the introduction to this analysis, it is assumed
that likely consequences are somewhat higher for species of mysticete
whales (low-frequency hearing specialists) due to the greater potential
for masking impacts at longer ranges than other taxa and at frequencies
that overlap a larger portion of both their hearing and vocalization
ranges. Therefore, despite de minimis magnitude ratings, we expect some
consequences to individual humpback, fin, and minke whales, i.e.,
leading to a low impact rating. However, given the minimal amount of
interaction expected between these species and the survey activities,
and in consideration of the overall low impact ratings, we find the
take from ION's planned survey activities will have a negligible impact
on the humpback whale, fin whale, and minke whale.
For those species with de minimis impact ratings we believe that,
absent additional relevant concerns related to population status or
context, the rating implies that a negligible impact should be expected
as a result of the specified activity. No such concerns exist for these
species, and we find the take from ION's planned survey activities will
have a negligible impact on all stocks of bottlenose dolphin, two
species of spotted dolphin, rough-toothed dolphin, striped dolphin,
common dolphin, Clymene dolphin, Risso's dolphin, and harbor porpoise.
In summary, based on the analysis contained herein of the likely
effects of the specified activity on marine mammals and their habitat,
and taking into consideration the implementation of the required
monitoring and mitigation measures, we find that the total marine
mammal take from ION's survey activities will have a negligible impact
on all affected marine mammal species or stocks.
Western--Western has planned a 208-day survey program, or 57
percent of the year (slightly more than two seasons). However, the
planned survey would cover a large spatial extent (i.e., a majority of
the mid- and south Atlantic; see Figures 1-1 to 1-4 of Western's
application). Therefore, although the survey would be long-term (i.e.,
greater than one season) in total duration, we would not expect the
duration of effect to be greater than moderate and intermittent in any
given area. Table 13 displays relevant information leading to impact
ratings for each species resulting from Western's survey. In general,
we note that although the temporal and spatial scale of the planned
survey activity is large, the fact that this mobile acoustic source
would be moving across large areas (as compared with geophysical
surveys with different objectives that may require focused effort over
long periods of time in smaller areas) means that more individuals may
receive limited exposure to survey noise, versus fewer individuals
receiving more intense exposure and/or for longer periods of time. The
nature of such potentially transitory exposure (which we nevertheless
assume here is of moderate duration and intermittent, versus isolated)
means that the potential significance of behavioral disruption and
potential for longer-term avoidance of important areas is limited.
Table 13--Magnitude and Impact Ratings, Western
--------------------------------------------------------------------------------------------------------------------------------------------------------
Species Amount Spatial extent Magnitude rating Consequences Impact rating \1\
--------------------------------------------------------------------------------------------------------------------------------------------------------
North Atlantic right whale......... De minimis............ Low-Moderate.......... De minimis........... Medium............... Low.
Humpback whale..................... De minimis............ Low-Moderate.......... De minimis........... Medium............... Low.
Minke whale........................ De minimis............ Low-High.............. De minimis........... Medium............... Low.
Fin whale.......................... Low................... Low................... Medium............... Medium............... Moderate.
Sperm whale........................ Moderate.............. Moderate.............. High................. Medium............... High.
Kogia spp.......................... Moderate.............. High.................. High................. Low.................. Moderate.
Beaked whales...................... Moderate.............. Moderate.............. High................. High................. High.
Rough-toothed dolphin.............. Low................... High.................. High................. Low.................. Moderate.
Bottlenose dolphin................. Moderate.............. High.................. High................. Low.................. Moderate.
Clymene dolphin.................... De minimis............ High.................. De minimis........... Low.................. De minimis.
Atlantic spotted dolphin........... Moderate.............. Moderate.............. High................. Low.................. Moderate.
Pantropical spotted dolphin........ Low................... High.................. High................. Low.................. Moderate.
Striped dolphin.................... Low................... Low................... Medium............... Low.................. Low.
Common dolphin..................... Low................... Low-moderate.......... Medium............... Low.................. Low.
Risso's dolphin.................... Low................... Low-moderate.......... Medium............... Low.................. Low.
Pilot whales....................... Low................... Moderate.............. Medium............... Medium............... Moderate.
[[Page 63373]]
Harbor porpoise.................... De minimis............ Low................... De minimis........... Low.................. De minimis
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Impact rating does not indicate whether overall impact to the species or stock is negligible, but is considered with relevant contextual factors
(described generally above and specifically below) in order to ultimately determine whether the effects of the specified activity on the affected
species or stock are negligible.
The North Atlantic right whale is endangered, has a very low
population size, and faces significant additional stressors. Therefore,
regardless of impact rating, we believe that the required mitigation
described previously is critically important in order for us to make
the necessary finding and it is with consideration of this mitigation
that we find the take from Western's survey activities will have a
negligible impact on the North Atlantic right whale. The fin whale
receives a moderate impact rating overall, but we expect that for two
seasons (summer and fall) almost no fin whales will be present in the
survey area. For the remainder of the year, it is likely that less than
one quarter of the population will be present within the survey area
(Roberts et al., 2016), meaning that despite medium rankings for
magnitude and likely consequences, these impacts would be experienced
by only a small subset of the overall population. In consideration of
the moderate impact rating, the likely proportion of the population
that may be affected by the specified activities, and the lack of
evidence that the survey area is host to important behaviors that may
be disrupted, we find the take from Western's survey activities will
have a negligible impact on the fin whale.
Magnitude ratings for the sperm whale and beaked whales are high
and, further, consequence factors reinforce high impact ratings for
both. Magnitude rating for pilot whales is medium but, similar to
beaked whales, we expect that compensatory ability will be low (high
consequence rating) due to presumed residency in areas targeted by the
planned survey--leading to a moderate impact rating. However,
regardless of impact rating, the consideration of likely consequences
and contextual factors for all three taxa leads us to conclude that
targeted mitigation is important to support a finding that the effects
of the survey will have a negligible impact on these species. As
described previously, sperm whales are an endangered species with
particular susceptibility to disruption of foraging behavior, beaked
whales are particularly acoustically sensitive (with presumed low
compensatory ability), and pilot whales are sensitive to additional
stressors due to a high degree of mortality in commercial fisheries
(and also with low compensatory ability). Finally, due to their
acoustic sensitivity, we have required shutdown of the acoustic source
upon observation of a beaked whale at extended distance from the source
vessel. In consideration of the required mitigation, we find the take
from Western's survey activities will have a negligible impact on the
sperm whale, beaked whales (i.e., Ziphius cavirostris and Mesoplodon
spp.), and pilot whales (i.e., Globicephala spp.).
Kogia spp. receive a moderate impact rating. However, although NMFS
does not currently identify a trend for these populations, recent
survey effort and stranding data show a simultaneous increase in at-sea
abundance and strandings, suggesting growing Kogia spp. abundance
(NMFS, 2011; 2013a; Waring et al., 2007; 2013). Finally, we expect that
Kogia spp. will receive subsidiary benefit from the mitigation targeted
for sperm whales, beaked whales, and pilot whales and, although
minimally effective due to the difficulty of at-sea observation of
Kogia spp., we have required shutdown of the acoustic source upon
observation of Kogia spp. at extended distance from the source vessel.
In consideration of these factors--likely population increase and
required mitigation--we find the take from Western's survey activities
will have a negligible impact on Kogia spp.
As described in the introduction to this analysis, it is assumed
that likely consequences are somewhat higher for species of mysticete
whales (low-frequency hearing specialists) due to the greater potential
for masking impacts at longer ranges than other taxa and at frequencies
that overlap a larger portion of both their hearing and vocalization
ranges. Therefore, despite de minimis magnitude ratings, we expect some
consequences to individual humpback and minke whales, i.e., leading to
a low impact rating. However, given the minimal amount of interaction
expected between these species and the survey activities, and in
consideration of the overall low impact ratings, we find the take from
Western's planned survey activities will have a negligible impact on
the humpback whale and minke whale.
Despite medium to high magnitude ratings (with the exception of the
Clymene dolphin), remaining delphinid species receive low to moderate
impact ratings due to consequences relating to a lack of propensity for
behavioral disruption due to airgun survey activity and our expectation
that these species would generally have relatively high compensatory
ability. In addition, contextually these species do not have
significant issues relating to population status or context. Many
oceanic delphinid species are generally more associated with dynamic
oceanographic characteristics rather than static physical features, and
those species (such as common dolphin) with substantial distribution to
the north of the survey area would likely be little affected at the
population level by the specified activity. For example, both species
of spotted dolphin and the offshore stock of bottlenose dolphin range
widely over slope and abyssal waters (e.g., Waring et al., 2014; Hayes
et al., 2017; Roberts et al., 2016), while the rough-toothed dolphin
does not appear bound by water depth in its range (Ritter, 2002; Wells
et al., 2008). Our required mitigation largely eliminates potential
effects to depleted coastal stocks of bottlenose dolphin. We also
expect that meaningful subsidiary benefit will accrue to certain
species from the mitigation targeted for sperm whales, beaked whales,
and pilot whales, most notably to species presumed to have greater
association with shelf break waters north of Cape Hatteras (e.g.,
offshore bottlenose dolphins, common dolphins, and Risso's dolphins).
In consideration of these factors--overall impact ratings and context
including required mitigation--we find the take from Western's survey
activities will have a negligible impact on most remaining delphinid
species (i.e., all stocks of bottlenose dolphin, two species of spotted
dolphin, rough-toothed dolphin, striped dolphin, common dolphin, and
Risso's dolphin).
For those species with de minimis impact ratings we believe that,
absent additional relevant concerns related to
[[Page 63374]]
population status or context, the rating implies that a negligible
impact should be expected as a result of the specified activity. No
such concerns exist for these species, and we find the take from
Western's survey activities will have a negligible impact on the
Clymene dolphin and harbor porpoise.
In summary, based on the analysis contained herein of the likely
effects of the specified activity on marine mammals and their habitat,
and taking into consideration the implementation of the required
monitoring and mitigation measures, we find that the total marine
mammal take from Western's survey activities will have a negligible
impact on all affected marine mammal species or stocks.
CGG--CGG has planned an approximately 155-day survey program, or 42
percent of the year (approximately two seasons). However, the planned
survey would cover a large spatial extent (i.e., a majority of the mid-
and south Atlantic; see Figure 3 of CGG's application). Therefore,
although the survey would be long-term (i.e., greater than one season)
in total duration, we would not expect the duration of effect to be
greater than moderate and intermittent in any given area. Table 14
displays relevant information leading to impact ratings for each
species resulting from CGG's survey. In general, we note that although
the temporal and spatial scale of the planned survey activity is large,
the fact that this mobile acoustic source would be moving across large
areas (as compared with geophysical surveys with different objectives
that may require focused effort over long periods of time in smaller
areas) means that more individuals may receive limited exposure to
survey noise, versus fewer individuals receiving more intense exposure
and/or for longer periods of time. The nature of such potentially
transitory exposure means that the potential significance of behavioral
disruption and potential for longer-term avoidance of important areas
is limited.
Table 14--Magnitude and Impact Ratings, CGG
--------------------------------------------------------------------------------------------------------------------------------------------------------
Species Amount Spatial extent Magnitude rating Consequences Impact rating \1\
--------------------------------------------------------------------------------------------------------------------------------------------------------
North Atlantic right whale......... De minimis............ Low-Moderate.......... De minimis........... Medium............... Low.
Humpback whale..................... De minimis............ Low-Moderate.......... De minimis........... Medium............... Low.
Minke whale........................ De minimis............ Low-High.............. De minimis........... Medium............... Low.
Fin whale.......................... De minimis............ Low................... De minimis........... Medium............... Low.
Sperm whale........................ Low................... Moderate.............. Medium............... Medium............... Moderate.
Kogia spp.......................... Low................... High.................. High................. Low.................. Moderate.
Beaked whales...................... Low................... Moderate.............. Medium............... High................. Moderate.
Rough-toothed dolphin.............. Moderate.............. High.................. High................. Low.................. Moderate.
Bottlenose dolphin................. Low................... High.................. High................. Low.................. Moderate.
Clymene dolphin.................... High.................. High.................. High................. Low.................. Moderate.
Atlantic spotted dolphin........... Low................... Moderate.............. Medium............... Low.................. Low.
Pantropical spotted dolphin........ Moderate.............. High.................. High................. Low.................. Moderate.
Striped dolphin.................... De minimis............ Low................... De minimis........... Low.................. De minimis.
Common dolphin..................... De minimis............ Low-moderate.......... De minimis........... Low.................. De minimis.
Risso's dolphin.................... De minimis............ Low-moderate.......... De minimis........... Low.................. De minimis.
Pilot whales....................... Low................... Moderate.............. Medium............... Medium............... Moderate.
Harbor porpoise.................... De minimis............ Low................... De minimis........... Low.................. De minimis.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Impact rating does not indicate whether overall impact to the species or stock is negligible, but is considered with relevant contextual factors
(described generally above and specifically below) in order to ultimately determine whether the effects of the specified activity on the affected
species or stock are negligible.
The North Atlantic right whale is endangered, has a very low
population size, and faces significant additional stressors. Therefore,
regardless of impact rating, we believe that the required mitigation
described previously is critically important in order for us to make
the necessary finding and it is with consideration of this mitigation
that we find the take from CGG's survey activities will have a
negligible impact on the North Atlantic right whale.
Magnitude ratings for the sperm whale and beaked whales are medium;
however, consequence factors are medium and high, respectively.
Magnitude rating for pilot whales is medium but, similar to beaked
whales, we expect that compensatory ability will be low (high
consequence rating) due to presumed residency in areas targeted by the
planned survey--leading to a moderate impact rating. However,
regardless of impact rating, the consideration of likely consequences
and contextual factors for all three taxa leads us to conclude that
targeted mitigation is important to support a finding that the effects
of the survey will have a negligible impact on these species. As
described previously, sperm whales are an endangered species with
particular susceptibility to disruption of foraging behavior, beaked
whales are particularly acoustically sensitive (with presumed low
compensatory ability), and pilot whales are sensitive to additional
stressors due to a high degree of mortality in commercial fisheries
(and also with low compensatory ability). Finally, due to their
acoustic sensitivity, we require shutdown of the acoustic source upon
detection of a beaked whale at extended distance from the source
vessel. In consideration of the required mitigation, we find the take
from CGG's survey activities will have a negligible impact on the sperm
whale, beaked whales (i.e., Ziphius cavirostris and Mesoplodon spp.),
and pilot whales (i.e., Globicephala spp.).
Kogia spp. receive a moderate impact rating. However, although NMFS
does not currently identify a trend for these populations, recent
survey effort and stranding data show a simultaneous increase in at-sea
abundance and strandings, suggesting growing Kogia spp. abundance
(NMFS, 2011; 2013a; Waring et al., 2007; 2013). Finally, we expect that
Kogia spp. will receive subsidiary benefit from the required mitigation
targeted for sperm whales, beaked whales, and pilot whales and,
although minimally effective due to the difficulty of at-sea
observation of Kogia spp., we have required shutdown of the acoustic
source upon observation of Kogia spp. at extended distance from the
source vessel. In consideration of these factors--likely population
increase and required mitigation--we find the take from CGG's survey
activities will have a negligible impact on Kogia spp.
[[Page 63375]]
As described in the introduction to this analysis, it is assumed
that likely consequences are somewhat higher for species of mysticete
whales (low-frequency hearing specialists) due to the greater potential
for masking impacts at longer ranges than other taxa and at frequencies
that overlap a larger portion of both their hearing and vocalization
ranges. Therefore, despite de minimis magnitude ratings, we expect some
consequences to individual humpback, fin, and minke whales, i.e.,
leading to a low impact rating. However, given the minimal amount of
interaction expected between these species and the survey activities,
and in consideration of the overall low impact ratings, we find the
take from CGG's planned survey activities will have a negligible impact
on the humpback whale, fin whale, and minke whale.
Despite medium to high magnitude ratings (with some exceptions),
most remaining delphinid species receive low to moderate impact ratings
due to consequences relating to a lack of propensity for behavioral
disruption due to airgun survey activity and our expectation that these
species would generally have relatively high compensatory ability. In
addition, contextually these species do not have significant issues
relating to population status or context. Many oceanic delphinid
species are generally more associated with dynamic oceanographic
characteristics rather than static physical features, and those species
(such as common dolphin) with substantial distribution to the north of
the survey area would likely be little affected at the population level
by the specified activity. For example, both species of spotted dolphin
and the offshore stock of bottlenose dolphin range widely over slope
and abyssal waters (e.g., Waring et al., 2014; Hayes et al., 2017;
Roberts et al., 2016), while the rough-toothed dolphin does not appear
bound by water depth in its range (Ritter, 2002; Wells et al., 2008).
Our required mitigation largely eliminates potential effects to
depleted coastal stocks of bottlenose dolphin. We also expect that
meaningful subsidiary benefit will accrue to certain species from the
mitigation targeted for sperm whales, beaked whales, and pilot whales,
most notably to species presumed to have greater association with shelf
break waters north of Cape Hatteras (e.g., offshore bottlenose
dolphins). In consideration of these factors--overall impact ratings
and context including required mitigation--we find the take from CGG's
survey activities will have a negligible impact on remaining delphinid
species (i.e., all stocks of bottlenose dolphin, two species of spotted
dolphin, rough-toothed dolphin, and Clymene dolphin).
For those species with de minimis impact ratings we believe that,
absent additional relevant concerns related to population status or
context, the rating implies that a negligible impact should be expected
as a result of the specified activity. No such concerns exist for these
species, and we find the take from CGG's survey activities will have a
negligible impact on the common dolphin, striped dolphin, Risso's
dolphin, and harbor porpoise.
In summary, based on the analysis contained herein of the likely
effects of the specified activity on marine mammals and their habitat,
and taking into consideration the implementation of the required
monitoring and mitigation measures, we find that the total marine
mammal take from CGG's survey activities will have a negligible impact
on all affected marine mammal species or stocks.
Small Numbers Analyses
The MMPA does not define ``small numbers.'' NMFS's and the U.S.
Fish and Wildlife Service's 1989 implementing regulations defined small
numbers as a portion of a marine mammal species or stock whose taking
would have a negligible impact on that species or stock. This
definition was invalidated in Natural Resources Defense Council v.
Evans, 279 F.Supp.2d 1129 (2003) (N.D. Cal. 2003), based on the court's
determination that the regulatory definition of small numbers was
improperly conflated with the regulatory definition of ``negligible
impact,'' which rendered the small numbers standard superfluous. As the
court observed, ``the plain language indicates that small numbers is a
separate requirement from negligible impact.'' Since that time, NMFS
has not applied the definition found in its regulations. Rather,
consistent with Congress' pronouncement that small numbers is not a
concept that can be expressed in absolute terms (House Committee on
Merchant Marine and Fisheries Report No. 97-228 (September 16, 1981)),
NMFS makes its small numbers findings based on an analysis of whether
the number of individuals authorized to be taken annually from a
specified activity is small relative to the stock or population size.
The Ninth Circuit has upheld a similar approach. See Center for
Biological Diversity v. Salazar, No. 10-35123, 2012 WL 3570667 (9th
Cir. Aug. 21, 2012). However, we have not historically indicated what
we believe the upper limit of small numbers is.
To maintain an interpretation of small numbers as a proportion of a
species or stock that does not conflate with negligible impact, we use
the following framework. A plain reading of ``small'' implies as
corollary that there also could be ``medium'' or ``large'' numbers of
animals from the species or stock taken. We therefore use a simple
approach that establishes equal bins corresponding to small, medium,
and large proportions of the population abundance.
NMFS's practice for making small numbers determinations is to
compare the number of individuals estimated and authorized to be taken
(often using estimates of total instances of take, without regard to
whether individuals are exposed more than once) against the best
available abundance estimate for that species or stock. We note,
however, that although NMFS's implementing regulations require
applications for incidental take to include an estimate of the marine
mammals to be taken, there is nothing in paragraphs (A) or (D) of
section 101(a)(5) that requires NMFS to quantify or estimate numbers of
marine mammals to be taken for purposes of evaluating whether the
number is small. (See CBD v. Salazar.) While it can be challenging to
predict the numbers of individual marine mammals that will be taken by
an activity (again, many models calculate instances of take and are
unable to account for repeated exposures of individuals), in some cases
we are able to generate a reasonable estimate utilizing a combination
of quantitative tools and qualitative information. When it is possible
to predict with relative confidence the number of individual marine
mammals of each species or stock that are likely to be taken, the small
numbers determination should be based directly upon whether or not
these estimates exceed one third of the stock abundance. In other
words, consistent with past practice, when the estimated number of
individual animals taken (which may or may not be assumed as equal to
the total number of takes, depending on the available information) is
up to, but not greater than, one third of the species or stock
abundance, NMFS will determine that the numbers of marine mammals taken
of a species or stock are small.
Another circumstance in which NMFS considers it appropriate to make
a small numbers finding is in the case of a species or stock that may
potentially be taken but is either rarely encountered or only expected
to be taken on rare occasions. In that
[[Page 63376]]
circumstance, one or two assumed encounters with a group of animals
(meaning a group that is traveling together or aggregated, and thus
exposed to a stressor at the same approximate time) should reasonably
be considered small numbers, regardless of consideration of the
proportion of the stock (if known), as rare encounters resulting in
take of one or two groups should be considered small relative to the
range and distribution of any stock.
In summary, when quantitative take estimates of individual marine
mammals are available or inferable through consideration of additional
factors, and the number of animals taken is one third or less of the
best available abundance estimate for the species or stock, NMFS
considers it to be of small numbers. NMFS may appropriately find that
one or two predicted group encounters will result in small numbers of
take relative to the range and distribution of a species, regardless of
the estimated proportion of the abundance.
Please see Table 15 for information relating to the basis for our
small numbers analyses. For the sei whale, Bryde's whale, blue whale,
northern bottlenose whale, Fraser's dolphin, melon-headed whale, false
killer whale, pygmy killer whale, killer whale, spinner dolphin, and
white-sided dolphin, we authorize take resulting from a single exposure
of one group of each species or stock, as appropriate (using average
group size), for each applicant. We believe that a single incident of
take of one group of any of these species represents take of small
numbers for that species. Therefore, for each applicant, based on the
analyses contained herein of their specified activity, we find that
small numbers of marine mammals will be taken for each of these 11
affected species or stocks for each specified activity. We do not
discuss these 11 species further in the applicant-specific analyses
that follow.
Table 15--Total Instances of Take Authorized 1 and Proportion of Best Abundance Estimate 2
--------------------------------------------------------------------------------------------------------------------------------------------------------
Abundance Spectrum \8\ TGS \3\ ION Western CGG
Common name estimate -------------------------------------------------------------------------------------------------------------
\4\ Take % Take % Take % Take % Take %
--------------------------------------------------------------------------------------------------------------------------------------------------------
North Atlantic right whale... 458 6 1 9 2 2 <1 4 1 2 <1
Humpback whale............... \5\ 2,002 45 2 60 3 7 <1 49 2 7 <1
Minke whale.................. 20,741 423 2 212 1 12 <1 100 <1 128 1
Fin whale.................... \5\ 6,582 337 5 1,144 17 5 <1 537 8 49 1
Sperm whale.................. \5\ 9,649 1,077 11 3,579 37 16 <1 1,941 20 1,304 14
Kogia spp.................... 3,785 205 5 1,221 32 30 1 572 15 240 6
Beaked whales................ \6\ 25,284 3,357 13 12,072 48 490 2 4,960 20 3,511 14
Rough-toothed dolphin........ \7\ 845 201 24 261 31 14 2 123 15 177 21
Bottlenose dolphin........... \5\ 149,785 37,562 25 40,595 27 2,599 2 23,600 16 9,063 6
Clymene dolphin.............. \7\ 24,018 6,459 27 821 3 252 1 391 2 6,382 27
Atlantic spotted dolphin..... \6\ 107,100 16,926 16 41,222 38 568 1 18,724 17 6,596 6
Pantropical spotted dolphin.. \7\ 7,217 1,632 23 1,470 20 78 1 690 10 1,566 22
Striped dolphin.............. \6\ 158,258 8,022 5 23,418 15 162 <1 8,845 6 6,328 4
Common dolphin............... 173,486 11,087 6 52,728 30 372 <1 20,683 12 6,026 3
Risso's dolphin.............. \5\ 19,437 755 4 3,241 17 90 <1 1,608 8 809 4
Globicephala spp............. \6\ 34,531 2,765 8 8,902 26 199 1 4,682 14 1,964 6
Harbor porpoise.............. \5\ 50,406 627 1 325 1 21 <1 155 <1 30 <1
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Total take authorized includes take by Level A and Level B harassment. Please see Table 6 for details.
\2\ Species for which take resulting from a single exposure of one group of each species or stock are not included in this table. Please see discussion
preceding this table.
\3\ Additional analysis was conducted to specify the number of individuals taken for TGS. Please see discussion below and Table 16.
\4\ Best abundance estimate; please see discussion under ``Description of Marine Mammals in the Area of the Specified Activities.'' For most taxa, the
best abundance estimate for purposes of comparison with take estimates is considered here to be the model-predicted abundance (Roberts et al., 2016).
For these taxa, model-predicted abundances within the EEZ and estimates for the portion of the specific geographic region beyond the EEZ are combined
to obtain the total abundance. For those taxa where a density surface model was produced, maximum monthly abundance was considered appropriate for
some, and for others the maximum mean seasonal abundance was used as a precaution. For those taxa where only a stratified model was produced, only
mean annual abundance is available. For several taxa, other abundance estimates were deemed most appropriate, as described previously in this notice.
\5\ Maximum monthly abundance.
\6\ Maximum seasonal abundance.
\7\ Mean annual abundance.
\8\ Small numbers analyses were completed prior to receipt of a modified survey plan from Spectrum and subsequent revision of authorized take numbers
reflecting the modification. Here, we retain the original take estimates for Spectrum in context of the small numbers analysis described below. Please
see ``Spectrum Survey Plan Modification,'' below, for additional information describing the modified survey plan, findings made in context of the
analysis presented below, and authorized take for Spectrum (Table 17).
As discussed previously, the MMPA does not define small numbers.
NMFS compares the estimated numbers of individuals expected to be taken
(when available; often take estimates are presented as estimated
instances of take) to the most appropriate estimation of the relevant
species or stock size in our determination of whether an authorization
is limited to small numbers of marine mammals, i.e., less than one-
third of the most appropriate abundance estimate (Table 15). In the
Notice of Proposed Authorization, we proposed to limit the
authorization of take to approximately one-third of the most
appropriate stock abundance estimate, assuming no other relevant
factors that provide more context for the estimate (e.g., information
that the take estimate numbers represent instances of multiple
exposures of the same animals). Further, we proposed that, in order to
limit actual take to this proportion of estimated stock abundance, we
would require monthly reporting from those applicants with predicted
exposures of any species exceeding this threshold. Those interim
reports would include corrected numbers of marine mammals ``taken''
and, upon reaching the pre-determined take threshold, any issued IHA
would be withdrawn.
However, as discussed elsewhere in this notice (including in
``Comments and Responses''), we received numerous comments criticizing
this approach. Notably, comments indicated that the pre-determined
threshold (described in our Notice of Proposed IHAs as30 percent) was
arbitrary and not rooted in any meaningful biological consideration,
and that the proposal--i.e., to limit the actual take authorization to
less than what was estimated in terms of potential exposures, require a
novel reporting scheme, and potentially withdraw IHAs if the threshold
was crossed--was impracticable. However, in this Notice we have more
fully described and clarified our approach to small numbers, and used
this approach for
[[Page 63377]]
issuance of the IHAs. As a result of the concerns presented by
applicants and commenters regarding the justification for and
practicability of our proposal, we reconsidered the available
information and re-evaluated and refined our small numbers analyses, as
described next. With regard to use of the most appropriate population
abundance (Table 15), please see additional discussion under
``Description of Marine Mammals in the Area of the Specified
Activities.''
The number of exposures presented in Table 15 represent the
estimated number of instantaneous instances in which an individual from
each species or stock would be exposed to sound fields from airgun
surveys at or above the 160 dB rms threshold. They do not necessarily
represent the estimated number of individuals of each species that
would be exposed, nor do they provide information on the duration of
the exposure. In this case, the likelihood that any individual of a
given species is exposed more than once is low due to the movement of
both the vessels and the animals themselves. That said, for species
where the estimated exposure numbers are higher compared to the
population abundance, we assume that some individuals may be exposed
more than once, meaning the exposures given in Table 15 overestimate
the numbers of individuals that would be exposed. Applicant-specific
analyses follow.
Spectrum--The total amount of taking assessed for all affected
stocks on the basis of Spectrum's original survey plan ranges from 1 to
27 percent of the most appropriate population abundance estimate, and
is therefore less than the appropriate small numbers threshold (i.e.,
one-third of the most appropriate population abundance estimate). These
proportions are considered overestimates with regard to the small
numbers findings, as they likely represent multiple exposures of some
of the same individuals for some stocks. However, we do not have
sufficient information on which to base an estimate of individuals
taken versus instances of take. Please see ``Spectrum Survey Plan
Modification,'' below, for additional information describing the
modified survey plan, findings made in context of the analysis
presented here, and authorized take for Spectrum (Table 17).
Based on the analysis contained herein of Spectrum's specified
activity, the required monitoring and mitigation measures, and the
anticipated take of marine mammals, we find that small numbers of
marine mammals will be taken relative to the population sizes of the
affected species or stocks.
TGS--The total amount of taking (in consideration of instances of
take) authorized for a majority of affected stocks ranges from 1 to 32
percent of the most appropriate population abundance estimate, and is
therefore less than the appropriate small numbers threshold (i.e., one-
third of the most appropriate population abundance estimate). The total
amount of taking (in consideration of instances of take) authorized for
the sperm whale, beaked whales, and the Atlantic spotted dolphin is
higher than the threshold. In this case, we have information available
to distinguish between an estimate of individuals taken versus
instances of take.
TGS is the only applicant that provided an analysis of estimated
individuals exposed versus instances of exposure (see Table 6-5 of
TGS's application). As described in the introduction to this section,
the number of individuals taken (versus total instances of take), is
the relevant metric for comparison to population abundance in a small
numbers analysis. We note, though, that total instances of take are
routinely used to evaluate small numbers when data to distinguish
individuals is not available, and we further note the conservativeness
of the assumption, as the number of total instances of take equates to
the highest possible number of individuals. For example, in some cases
the total number of takes may exceed the number of individuals in a
population abundance, meaning there are multiple exposures of at least
some animals.
We do not typically attempt to quantitatively assess this
comparison of individuals taken versus instances of take when we do not
have direct information regarding individuals exposed (e.g., we know
that only a specific sub-population is potentially exposed or we know
that uniquely identified individuals are exposed); therefore, we did
not initially make use of the information provided by TGS in their
application, instead proposing the take cap and reporting scheme
described in the introduction to this section. As described above,
commenters indicated that our proposed approach was flawed and,
therefore, we further evaluated the available information.
The conceptual approach to the analysis involves a comparison of
total ensonified area to the portion of that total area that is
ensonified more than once. For TGS, 84 percent of the total ensonified
area is area that is ensonified more than once, i.e., ``overlap.'' In a
static density model, the same animals occur in the overlap regardless
of the time elapsed between the first and second exposure. If animals
are static in space in the model, they are re-exposed in the model
every time there is overlap. When overlap is counted toward the
evaluation of small numbers (i.e., percent of the abundance that is
``taken''), it effectively raises the total abundance possible in the
model, creating a situation in which one could theoretically take more
than the abundance to which one is comparing. This does not make sense
from the perspective of comparing numbers of individuals taken to total
abundance. Although portions of the overlap may be ensonified more than
twice, we conservatively assume a maximum of one repeat ensonification.
The number of individuals potentially taken (versus total incidents
of take) can then be determined using the following equation:
(Numerical Output of the Model)-(0.84 * Numerical Output of the Model)
+ 0.5 * (0.84 * Numerical Output of the Model). This may be simplified
as: 0.58 * Numerical Output of the Model. ``Numerical output of the
model'' refers to the estimated total incidents of take. As we stated
in the introduction to this section, where there are relatively few
total takes, it is more likely that all takes occur to new individuals,
though this is dependent on actual distribution and movement of animals
in relation to the survey vessel. While there is no clear threshold as
to what level of total takes indicates a likelihood of repeat taking of
individuals, here we assume that total taking of a moderate or high
magnitude (consistent with our approach to assessing magnitude in the
negligible impact analysis framework; see ``Negligible Impact Analyses
and Determinations''), i.e., greater than 15 percent, is required for
repeat taking of individuals to be likely and applied this analysis
only to those stocks.
Table 16--Analysis of Individuals Taken Versus Total Takes, TGS
--------------------------------------------------------------------------------------------------------------------------------------------------------
Abundance Individuals Individuals Individuals
Common name estimate Total take % taken % taken once taken twice
--------------------------------------------------------------------------------------------------------------------------------------------------------
Fin whale........................................................ 6,582 1,144 17 664 10 480 184
[[Page 63378]]
Sperm whale...................................................... 9,649 3,579 37 2,076 22 1,503 573
Kogia spp........................................................ 3,785 1,221 32 708 19 513 195
Beaked whales.................................................... 25,284 12,072 48 7,002 28 5,070 1,932
Rough-toothed dolphin............................................ 845 261 31 151 18 110 42
Bottlenose dolphin............................................... 149,785 40,595 27 23,545 16 17,050 6,495
Atlantic spotted dolphin......................................... 107,100 41,222 38 23,909 22 17,313 6,596
Pantropical spotted dolphin...................................... 7,217 1,470 20 853 12 617 235
Common dolphin................................................... 173,486 52,728 30 30,582 18 22,146 8,436
Risso's dolphin.................................................. 19,437 3,241 17 1,880 10 1,361 519
Globicephala spp................................................. 34,531 8,902 26 5,163 15 3,739 1,424
--------------------------------------------------------------------------------------------------------------------------------------------------------
This approach also allows us to estimate the number of individuals
that we assume to be taken once and the number assumed to be taken
twice. As we noted previously, although it is possible that some
individuals may be taken more than twice, we assume a maximum of one
repeat ensonification (a conservative assumption in this small numbers
analysis context). For example, if there are 1,144 total takes of fin
whales, with 664 total individuals taken, and where:
a = number of animals with single take; b = number of animals with
double take,
then: a + b = 664 and 2*a + b = 1,144 and, therefore, 2*a + 664-a =
1,144. In this example for fin whales, we assume that 480
individuals are taken twice and 184 individuals are taken once.
(Note that values given in Table 16 for individuals taken once
versus twice may not sum to the value given for total individuals
taken due to rounding.)
In summary, for those stocks for which we assume each authorized
take represents a new individual, the total amount of taking authorized
ranges from 1 to 15 percent of the most appropriate population
abundance estimate (Table 15), and is therefore less than the
appropriate small numbers threshold (i.e., one-third of the most
appropriate population abundance estimate). For those stocks for which
we assessed the number of expected individuals taken, the total amount
of taking authorized ranges from 10 to 28 percent of the most
appropriate population abundance estimate (Table 16), and is therefore
less than the appropriate small numbers threshold (i.e., one-third of
the most appropriate population abundance estimate). Based on the
analysis contained herein of TGS's specified activity, the required
monitoring and mitigation measures, and the anticipated take of marine
mammals, we find that small numbers of marine mammals will be taken
relative to the population sizes of the affected species or stocks.
ION--The total amount of taking authorized for all affected stocks
ranges from less than 1 to 4 percent of the most appropriate population
abundance estimate, and is therefore less than the appropriate small
numbers threshold (i.e., one-third of the most appropriate population
abundance estimate).
Based on the analysis contained herein of ION's specified activity,
the required monitoring and mitigation measures, and the anticipated
take of marine mammals, we find that small numbers of marine mammals
will be taken relative to the population sizes of the affected species
or stocks.
Western--The total amount of taking authorized for all affected
stocks ranges from less than 1 to 20 percent of the most appropriate
population abundance estimate, and is therefore less than the
appropriate small numbers threshold (i.e., one-third of the most
appropriate population abundance estimate). These proportions are
considered overestimates with regard to the small numbers findings, as
they likely represent multiple exposures of some of the same
individuals for some stocks. However, we do not have sufficient
information on which to base an estimate of individuals taken versus
instances of take.
Based on the analysis contained herein of Western's specified
activity, the required monitoring and mitigation measures, and the
anticipated take of marine mammals, we find that small numbers of
marine mammals will be taken relative to the population sizes of the
affected species or stocks.
CGG--The total amount of taking authorized for all affected stocks
ranges from less than 1 to 27 percent of the most appropriate
population abundance estimate, and is therefore less than the
appropriate small numbers threshold (i.e., one-third of the most
appropriate population abundance estimate). These proportions are
considered overestimates with regard to the small numbers findings, as
they likely represent multiple exposures of some of the same
individuals for some stocks. However, we do not have sufficient
information on which to base an estimate of individuals taken versus
instances of take.
Based on the analysis contained herein of CGG's specified activity,
the required monitoring and mitigation measures, and the anticipated
take of marine mammals, we find that small numbers of marine mammals
will be taken relative to the population sizes of the affected species
or stocks.
Impact on Availability of Affected Species for Taking for Subsistence
Uses
There are no relevant subsistence uses of marine mammals implicated
by these actions. Therefore, relevant to the Spectrum, TGS, ION, CGG,
and Western IHAs, we have determined that the total taking of affected
species or stocks would not have an unmitigable adverse impact on the
availability of such species or stocks for taking for subsistence
purposes.
Spectrum Survey Plan Modification
As described earlier in this notice, Spectrum's proposed survey
plan described in our Notice of Proposed IHAs included ~21,635 km of
survey line (see Figure 1 of Spectrum's application). However, on June
4, 2018, Spectrum notified NMFS of a modification to their survey plan.
NMFS's understanding is this modification is based on a voluntary
collaborative effort between Spectrum and TGS, another IHA applicant,
to reduce duplication of effort and expense. Subsequently, on June 26,
2018, Spectrum submitted a final, revised modified survey plan. The
modified survey plan occurs roughly within the same survey
``footprint'' and consists of ~13,766 km of survey line (see Figure
provided on p. 2 of Spectrum's letter notifying us of their intent to
modify their survey plan). Therefore, the modified survey plan
represents an approximate 36 percent decrease in total survey line.
With this reduction in survey effort, Spectrum now estimates that the
survey plan will require approximately 108 days of
[[Page 63379]]
operations (previously estimated as 165 days of operations).
The changes to the survey plan, in summary, include the following:
(1) Rotated the survey grid by approximately 5 degrees; (2) trimmed
lines from most time-area restrictions; (3) removed certain lines; and
(4) shifted certain lines. The figure provided on p. 3 of Spectrum's
letter notifying us of their intent to modify their survey plan shows
an overlay of the modified survey plan (red lines) with the previously
proposed survey plan (black lines).
Following receipt of the notification from Spectrum, we evaluated
the potential effect of the change through use of a spatial analysis.
In summary, we compared marine mammal densities within assumed
ensonified areas associated with the original survey tracklines and
associated with the modified survey tracklines. This allowed us to
produce a ratio of the expected takes by Level B harassment from the
modified survey to the original survey and, therefore, to evaluate the
degree of change in terms of take. In conducting this evaluation, we
used mean marine mammal densities over the 21 modeling areas or zones
(extracted from Roberts et al. (2016)), as described previously in
``Estimated Take.'' Detailed steps of the evaluation are as follows:
Obtain trackline lengths for each relevant season and zone
for proposed (i.e., the original) and modified Spectrum tracklines;
Multiply trackline lengths by mean buffer widths for each
zone to get area surveyed for both proposed and modified tracklines;
Multiply these areas surveyed within each zone by each
species density to get raw take by zone for proposed and modified
tracklines for each species (accounting for implementation of North
Atlantic right whale time-area restriction, in effect out to 90 km from
shore from November through April);
Create ratio of the expected take from the modified
tracklines to the proposed tracklines; and
Multiply this ratio by the originally proposed take
numbers to obtain revised take numbers.
However, note that we did not follow this process (i.e., developing
a ratio for use in ``correcting'' the original take number) for North
Atlantic right whales. Instead, we performed an identical analysis as
that described previously in ``Description of Exposure Estimates--North
Atlantic Right Whale,'' producing a new take estimate for this species
(Table 17).
The results of this evaluation in terms of take numbers are shown
in Table 17. Our analysis of the potential for auditory injury of mid-
frequency cetaceans remains the same and, therefore, the amount of take
by Level A harassment for these species is unchanged. For low-frequency
cetaceans, the reduction in total survey line reduces the likely
potential that take by Level A harassment would occur. The total amount
of survey line in the modified survey plan is similar to that proposed
by ION and, in fact, Spectrum's estimated auditory injury zone for low-
frequency cetaceans is slightly smaller than ION's. Therefore, we adopt
the logic presented previously for ION in revising the authorized take
by Level A harassment for low-frequency cetaceans (see ``Estimated
Take'' for more detail). For high-frequency cetaceans, we revise the
take authorized by Level A harassment according to the same procedure
described previously in ``Estimated Take.'' For rarely occurring
species (i.e., sei whale, Bryde's whale, blue whale, northern
bottlenose whale, Fraser's dolphin, melon-headed whale, false killer
whale, pygmy killer whale, killer whale, spinner dolphin, and white-
sided dolphin), we retain our take authorization of a single exposure
of one group of each species or stock, as appropriate (using average
group size). Therefore, our original analysis is retained for these
species or stocks and we do not address them here.
Table 17--Take Estimates Associated With Proposed and Modified Tracklines and Proportion of Best Abundance Estimate
--------------------------------------------------------------------------------------------------------------------------------------------------------
Proposed tracklines Modified tracklines Reduction
------------------------------------------------------------------------------ in total
Common name authorized
Level A Level B % Level A Level B % take (%)
--------------------------------------------------------------------------------------------------------------------------------------------------------
North Atlantic right whale................................... 0 6 1 0 2 <1 67
Humpback whale............................................... 4 41 2 2 19 1 53
Minke whale.................................................. 4 419 2 2 252 1 40
Fin whale.................................................... 4 333 5 2 163 3 51
Sperm whale.................................................. 0 1,077 11 0 684 7 36
Kogia spp.................................................... 5 200 5 3 125 3 38
Beaked whales................................................ 0 3,357 13 0 2,291 9 32
Rough-toothed dolphin........................................ 0 201 24 0 117 14 42
Common bottlenose dolphin.................................... 0 37,562 25 0 14,938 10 60
Clymene dolphin.............................................. 0 6,459 27 0 4,045 17 37
Atlantic spotted dolphin..................................... 0 16,926 16 0 8,466 8 50
Pantropical spotted dolphin.................................. 0 1,632 23 0 1,017 14 38
Striped dolphin.............................................. 0 8,022 5 0 5,144 3 36
Common dolphin............................................... 0 11,087 6 0 6,008 3 46
Risso's dolphin.............................................. 0 755 4 0 414 2 45
Pilot whales................................................. 0 2,765 8 0 1,591 5 42
Harbor porpoise.............................................. 16 611 1 8 355 1 42
--------------------------------------------------------------------------------------------------------------------------------------------------------
Total authorized take for all species shown in Table 17 decreased.
The modified survey plan largely remains within the footprint of the
proposed survey plan, with the only notable change being the reduction
of total survey line and the removal of survey line from certain areas
within that footprint, including, importantly, the total removal of
lines from within our designated seasonal ``Hatteras and North'' time-
area restriction along the shelf break off of Cape Hatteras (Area #4;
Figure 4). This area constitutes some of the most important marine
mammal
[[Page 63380]]
habitat within the specific geographical region.
As previously described in ``Negligible Impact Analyses and
Determinations,'' we have determined on the basis of Spectrum's
proposed survey plan that the likely effects of the (previously
described) specified activity on marine mammals and their habitat due
to the total marine mammal take from Spectrum's survey activities would
have a negligible impact on all affected marine mammal species or
stocks. Based on our evaluation of Spectrum's modified survey plan, we
affirm that this conclusion remains valid, and we authorize the revised
take numbers shown in Table 17. Similarly, as previously described in
``Small Numbers Analyses,'' we have determined that the take of marine
mammals incidental to Spectrum's specified activity would represent
small numbers of marine mammals relative to the population sizes of the
affected species or stocks. All authorized take numbers for Spectrum
have decreased from what we considered in that small numbers analysis
and, therefore, we affirm that this conclusion remains valid.
In conclusion, we affirm and restate our findings for Spectrum:
All previously described mitigation, monitoring, and
reporting requirements remain the same. Based on our evaluation of
these measures, we have determined that the required mitigation
measures provide the means of effecting the least practicable adverse
impact on marine mammal species or stocks and their habitat, paying
particular attention to rookeries, mating grounds, and areas of similar
significance.
With regard to the negligible impact analysis, we refer
the reader to the analysis presented previously. In addition, our
evaluation of the modified survey plan shows (1) total survey line is
reduced by approximately one-third; (2) the modified survey plan does
not include new areas not originally considered in our assessment of
the effects of Spectrum's specified activity; (3) Spectrum has removed
lines from portions of the survey area, including important habitat for
marine mammals; and (4) authorized take for all taxa has been reduced.
Therefore, based on the analysis contained herein of the likely effects
of the specified activity on marine mammals and their habitat, and
taking into consideration the implementation of the required monitoring
and mitigation measures, we find that the total marine mammal take from
Spectrum's survey activities will have a negligible impact on the
affected marine mammal species or stocks.
With regard to the small numbers analysis, we refer the
reader to the analysis presented previously. Our evaluation of
Spectrum's modified survey plan results in a reduction of authorized
take for all taxa. Therefore, based on the analysis contained herein of
Spectrum's specified activity, the required monitoring and mitigation
measures, and the anticipated take of marine mammals, we find that
small numbers of marine mammals will be taken relative to the
population sizes of the affected species or stocks.
Endangered Species Act (ESA)
Section 7 of the ESA requires Federal agencies to insure that their
actions are not likely to jeopardize the continued existence of
endangered or threatened species or adversely modify or destroy their
designated critical habitat. Federal agencies must consult with NMFS
for actions that may affect species under NMFS's jurisdiction listed as
threatened or endangered or critical habitat designated for such
species.
At the conclusion of consultation, the consulting agency provides
an opinion stating whether the Federal agency's action is likely to
jeopardize the continued existence of ESA-listed species or destroy or
adversely modify designated critical habitat.
NMFS's issuance of IHAs to the five companies is subject to the
requirements of Section 7 of the ESA. Therefore, NMFS's Office of
Protected Resources (OPR), Permits and Conservation Division requested
initiation of a formal consultation with the NMFS OPR, ESA Interagency
Cooperation Division on the proposed issuance of IHAs on June 5, 2017.
The formal consultation concluded in November 2018 and a final
Biological Opinion (BiOp) was issued. The BiOp found that the Permits
and Conservation Division's proposed action of issuing the five IHAs is
not likely to jeopardize the continued existence or recovery of blue
whales, fin whales, North Atlantic right whales, sei whales, or sperm
whales. Furthermore, the BiOp found that the proposed action is also
not likely to adversely affect designated critical habitat for North
Atlantic right whales.
National Environmental Policy Act
In 2014, the BOEM produced a final Programmatic Environmental
Impact Statement (PEIS) to evaluate the direct, indirect, and
cumulative impacts of geological and geophysical survey activities on
the Mid- and South Atlantic OCS, pursuant to requirements of NEPA.
These activities include geophysical surveys in support of hydrocarbon
exploration, as were proposed in the MMPA applications before NMFS. The
PEIS is available at: www.boem.gov/Atlantic-G-G-PEIS/. NOAA, through
NMFS, participated in preparation of the PEIS as a cooperating agency
due to its legal jurisdiction and special expertise in conservation and
management of marine mammals, including its responsibility to authorize
incidental take of marine mammals under the MMPA.
NEPA, Council on Environmental Quality (CEQ) regulations, and
NOAA's NEPA implementing procedures (NOAA Administrative Order (NAO)
216-6A) encourage the use of programmatic NEPA documents and tiering to
streamline decision-making in staged decision-making processes that
progress from programmatic analyses to site-specific reviews. NMFS
reviewed the Final PEIS and determined that it meets the requirements
of the CEQ regulations (40 CFR part 1500-1508) and NAO 216-6A. NMFS
further determined, after independent review, that the Final PEIS
satisfied NMFS's comments and suggestions in the NEPA process. In our
Notice of Proposed IHAs, we stated our intention to adopt BOEM's
analysis in order to assess the impacts to the human environment of
issuance of the subject IHAs, and that we would review all comments
submitted in response to the notice as we completed the NEPA process,
including a final decision of whether to adopt BOEM's PEIS and sign a
Record of Decision related to issuance of IHAs. Following review of
public comments received, we confirmed that it would be appropriate to
adopt BOEM's analysis in order to support our assessment of the impacts
to the human environment of issuance of the subject IHAs. Therefore, on
February 23, 2018, NMFS signed a Record of Decision for the following
purposes: (1) To adopt the Final PEIS to support NMFS's analysis
associated with issuance of incidental take authorizations pursuant to
sections 101(a)(5)(A) or (D) of the MMPA and the regulations governing
the taking and importing of marine mammals (50 CFR part 216), and (2)
in accordance with 40 CFR 1505.2, to announce and explain the basis for
our decision to review and potentially issue incidental take
authorizations under the MMPA on a case-by-case basis, if appropriate.
Following review of public comment, we also determined that
conducting additional NEPA review and preparing a tiered Environmental
Assessment (EA) is appropriate to analyze environmental impacts
associated with NMFS's issuance of separate IHAs to five different
applicants. Through the description and analysis of NMFS's
[[Page 63381]]
activity provided in the EA as well as the analyses incorporated by
reference from the Notice of Proposed IHAs and BOEM's PEIS, NMFS found
that authorizing take of marine mammals by issuing individual IHAs to
the five applicants will not result in significant direct, indirect, or
cumulative impacts to the human environment. Accordingly, NMFS
determined that issuance of IHAs to the five applicants would not
significantly impact the quality of the human environment and signed a
Finding of No Significant Impact (FONSI). NMFS's ROD, EA, and FONSI are
available online at: www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-atlantic.
Authorizations
As a result of these determinations, NMFS has issued five separate
IHAs to the aforementioned applicant companies for conducting the
described geophysical survey activities in the Atlantic Ocean within
the specific geographic region, incorporating the previously mentioned
mitigation, monitoring, and reporting requirements.
Dated: November 30, 2018.
Donna S. Wieting,
Director, Office of Protected Resources, National Marine Fisheries
Service.
[FR Doc. 2018-26460 Filed 12-6-18; 8:45 am]
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