Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to Site Characterization Surveys Off the Coast of Massachusetts, 31856-31882 [2020-11203]
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DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric
Administration
[RTID 0648–XA065]
Takes of Marine Mammals Incidental to
Specified Activities; Taking Marine
Mammals Incidental to Site
Characterization Surveys Off the Coast
of Massachusetts
National Marine Fisheries
Service (NMFS), National Oceanic and
Atmospheric Administration (NOAA),
Commerce.
ACTION: Notice; proposed incidental
harassment authorization; request for
comments on proposed authorization
and possible renewal.
AGENCY:
NMFS has received a request
from Mayflower Wind Energy LLC
(Mayflower) for authorization to take
marine mammals incidental to site
characterization surveys off the coast of
Massachusetts in the area of the
Commercial Lease of Submerged Lands
for Renewable Energy Development on
the Outer Continental Shelf (OCS–A
0521) and along a potential submarine
cable route to landfall at Falmouth,
Massachusetts. Pursuant to the Marine
Mammal Protection Act (MMPA), NMFS
is requesting comments on its proposal
to issue an incidental harassment
authorization (IHA) to incidentally take
marine mammals during the specified
activities. NMFS is also requesting
comments on a possible one-year
renewal that could be issued under
certain circumstances and if all
requirements are met, as described in
Request for Public Comments at the end
of this notice. NMFS will consider
public comments prior to making any
final decision on the issuance of the
requested MMPA authorizations and
agency responses will be summarized in
the final notice of our decision.
DATES: Comments and information must
be received no later than June 26, 2020.
ADDRESSES: Comments should be
addressed to Jolie Harrison, Chief,
Permits and Conservation Division,
Office of Protected Resources, National
Marine Fisheries Service. Physical
comments should be sent to 1315 EastWest Highway, Silver Spring, MD 20910
and electronic comments should be sent
to ITP.Fowler@noaa.gov.
Instructions: NMFS is not responsible
for comments sent by any other method,
to any other address or individual, or
received after the end of the comment
period. Comments received
electronically, including all
attachments, must not exceed a 25-
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SUMMARY:
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megabyte file size. Attachments to
electronic comments will be accepted in
Microsoft Word or Excel or Adobe PDF
file formats only. All comments
received are a part of the public record
and will generally be posted online at
https://www.fisheries.noaa.gov/permit/
incidental-take-authorizations-undermarine-mammal-protection-act without
change. All personal identifying
information (e.g., name, address)
voluntarily submitted by the commenter
may be publicly accessible. Do not
submit confidential business
information or otherwise sensitive or
protected information.
FOR FURTHER INFORMATION CONTACT:
Amy Fowler, Office of Protected
Resources, NMFS, (301) 427–8401.
Electronic copies of the application and
supporting documents, as well as a list
of the references cited in this document,
may be obtained online at: https://
www.fisheries.noaa.gov/permit/
incidental-take-authorizations-undermarine-mammal-protection-act. In case
of problems accessing these documents,
please call the contact listed above.
SUPPLEMENTARY INFORMATION:
Background
The MMPA prohibits the ‘‘take’’ of
marine mammals, with certain
exceptions. Sections 101(a)(5)(A) and
(D) of the MMPA (16 U.S.C. 1361 et
seq.) direct 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 specified
geographical region if certain findings
are made and either regulations are
issued or, if the taking is limited to
harassment, a notice of a proposed
incidental take authorization may be
provided to the public for review.
Authorization for incidental takings
shall be granted if NMFS finds that the
taking will have a negligible impact on
the species or stock(s) and will not have
an unmitigable adverse impact on the
availability of the species or stock(s) for
taking for subsistence uses (where
relevant). Further, NMFS must prescribe
the permissible methods of taking and
other ‘‘means of effecting the least
practicable adverse impact’’ on the
affected species or stocks and their
habitat, paying particular attention to
rookeries, mating grounds, and areas of
similar significance, and on the
availability of the species or stocks for
taking for certain subsistence uses
(referred to in shorthand as
‘‘mitigation’’); and requirements
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pertaining to the mitigation, monitoring
and reporting of the takings are set forth.
National Environmental Policy Act
To comply with the National
Environmental Policy Act of 1969
(NEPA; 42 U.S.C. 4321 et seq.) and
NOAA Administrative Order (NAO)
216–6A, NMFS must review our
proposed action (i.e., the issuance of an
incidental harassment authorization)
with respect to potential impacts on the
human environment.
This action is consistent with
categories of activities identified in
Categorical Exclusion B4 (incidental
harassment authorizations with no
anticipated serious injury or mortality)
of the Companion Manual for NOAA
Administrative Order 216–6A, which do
not individually or cumulatively have
the potential for significant impacts on
the quality of the human environment
and for which we have not identified
any extraordinary circumstances that
would preclude this categorical
exclusion. Accordingly, NMFS has
preliminarily determined that the
issuance of the proposed IHA qualifies
to be categorically excluded from
further NEPA review.
We will review all comments
submitted in response to this notice
prior to concluding our NEPA process
or making a final decision on the IHA
request.
Summary of Request
On January 17, 2020, NMFS received
a request from Mayflower for an IHA to
take marine mammals incidental to site
characterization surveys in the area of
the Commercial Lease of Submerged
Lands for Renewable Energy
Development on the Outer Continental
Shelf (OCS–A 0521; Lease Area) and a
submarine export cable route
connecting the Lease Area to landfall in
Falmouth, Massachusetts. A revised
application was received on April 9,
2020. NMFS deemed that request to be
adequate and complete. Mayflower’s
request is for take of a small number of
14 species of marine mammals by Level
B harassment only. Neither Mayflower
nor NMFS expects serious injury or
mortality to result from this activity
and, therefore, an IHA is appropriate.
Description of Proposed Activity
Overview
Mayflower proposes to conduct
marine site characterization surveys,
including high-resolution geophysical
(HRG) and geotechnical surveys, in the
area of Commercial Lease of Submerged
Lands for Renewable Energy
Development on the Outer Continental
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Shelf #OCS–A 0521 (Lease Area) and
along a potential submarine cable route
to landfall at Falmouth, Massachusetts.
The purpose of the proposed surveys
is to acquire geotechnical and HRG data
on the bathymetry, seafloor morphology,
subsurface geology, environmental/
biological sites, seafloor obstructions,
soil conditions, and locations of any
man-made, historical, or archaeological
resources within the Lease Area and
export cable route to support
development of offshore wind energy
facilities. Up to three survey vessels
may operate concurrently as part of the
proposed surveys, but the three vessels
will spend no more than a combined
total of 215 days at sea. Underwater
sound resulting from Mayflower’s
proposed site characterization surveys
has the potential to result in incidental
take of marine mammals in the form of
behavioral harassment.
Dates and Duration
The total duration of geophysical
survey activities would be
approximately 215 survey-days. This
schedule is based on 24-hour operations
in the offshore, deep-water portion of
the Lease Area, and 12-hour operations
in shallow-water and nearshore areas of
the export cable route. The surveys are
expected to occur between June and
September 2020.
Specific Geographic Region
Mayflower’s survey activities would
occur in the Northwest Atlantic Ocean
approximately 60 kilometers (km) south
of Martha’s Vineyard, Massachusetts.
All survey effort would occur within
U.S. Federal and state waters. Surveys
would occur within the Lease Area and
along a potential submarine cable route
connecting the Lease Area and landfall
at Falmouth, Massachusetts (see Figure
1 in Mayflower’s IHA application).
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Detailed Description of Specific Activity
Mayflower’s proposed marine site
characterization surveys include HRG
and geotechnical survey activities.
These survey activities would occur
within the Lease Area and within an
export cable route between the Lease
Area and Falmouth, Massachusetts. The
Lease Area is approximately 515.5
square kilometers (km2; 127,388 acres)
and lies approximately 20 nautical
miles (38 km south-southwest of
Nantucket. Water depths in the Lease
Area are approximately 38–62 meters
(m). For the purpose of this IHA the
Lease Area and export cable route are
collectively referred to as the Project
Area.
The proposed HRG and geotechnical
survey activities are described below.
Geotechnical Survey Activities
Mayflower’s proposed geotechnical
survey activities would include the
following:
• Sample boreholes and vibracores to
determine geological and geotechnical
characteristics of sediments; and
• Seabed core penetration tests
(CPTs) to determine stratigraphy and in
situ conditions of the sub-surface
sediments.
Geotechnical investigation activities
are anticipated to be conducted from up
to two vessels, each equipped with
dynamic positioning (DP) thrusters.
Impacts to the seafloor from this
equipment will be limited to the
minimal contact of the sampling
equipment, and inserted boring and
probes.
In considering whether marine
mammal harassment is an expected
outcome of exposure to a particular
activity or sound source, NMFS
considers the nature of the exposure
itself (e.g., the magnitude, frequency, or
duration of exposure), characteristics of
the marine mammals potentially
exposed, and the conditions specific to
the geographic area where the activity is
expected to occur (e.g., whether the
activity is planned in a foraging area,
breeding area, nursery or pupping area,
or other biologically important area for
the species). We then consider the
expected response of the exposed
animal and whether the nature and
duration or intensity of that response is
expected to cause disruption of
behavioral patterns (e.g., migration,
breathing, nursing, breeding, feeding, or
sheltering) or injury.
Geotechnical survey activities would
be conducted from drill ships equipped
with DP thrusters. DP thrusters would
be used to position the sampling vessel
on station and maintain position at each
sampling location during the sampling
activity. Sound produced through use of
DP thrusters is similar to that produced
by transiting vessels and DP thrusters
are typically operated either in a
similarly predictable manner or used for
short durations around stationary
activities. NMFS does not believe
acoustic impacts from DP thrusters are
likely to result in take of marine
mammals in the absence of activity- or
location-specific circumstances that
may otherwise represent specific
concerns for marine mammals (i.e.,
activities proposed in area known to be
of particular importance for a particular
species), or associated activities that
may increase the potential to result in
take when in concert with DP thrusters.
In this case, we are not aware of any
such circumstances. Therefore, NMFS
believes the likelihood of DP thrusters
used during the proposed geotechnical
surveys resulting in harassment of
marine mammals to be so low as to be
discountable. As DP thrusters are not
expected to result in take of marine
mammals, these activities are not
analyzed further in this document.
Field studies conducted off the coast
of Virginia to determine the underwater
noise produced by CPTs and borehole
drilling found that these activities did
not result in underwater noise levels
that exceeded current thresholds for
Level B harassment of marine mammals
(Kalapinski, 2015). Given the small size
and energy footprint of CPTs and boring
cores, NMFS believes the likelihood that
noise from these activities would exceed
the Level B harassment threshold at any
appreciable distance is so low as to be
discountable. Therefore, geotechnical
survey activities, including CPTs,
vibracores, and borehole drilling, are
not expected to result in harassment of
marine mammals and are not analyzed
further in this document.
Geophysical Survey Activities
Mayflower has proposed that HRG
survey activities would be conducted
continuously 24 hours per day in the
deep-water portion of the Project Area,
and 12 hours per day in the shallowwater portion of the survey area. Based
on this operation schedule, the
estimated total duration of the proposed
activities would be a combined total of
215 survey days. This includes 90 days
of surveys in the Lease Area and deepwater section of the export cable route,
95 days in the shallow-water section of
the cable route, and 30 days in the very
shallow section of the cable route
(waters less than 5 m deep) (see Table
1). These estimated durations include
potential weather down time.
TABLE 1—SUMMARY OF PROPOSED HRG SURVEY SEGMENTS
Survey area
Operating schedule
Lease Area and deep-water section of cable route .....................................................
24 hours/day .............................................
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Duration
(survey days)
90
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TABLE 1—SUMMARY OF PROPOSED HRG SURVEY SEGMENTS—Continued
Duration
(survey days)
Survey area
Operating schedule
Shallow-water section of cable route ...........................................................................
Very shallow cable route ..............................................................................................
12 hours/day (daylight only) .....................
12 hours/day (daylight only) .....................
95
30
All areas combined ...............................................................................................
...................................................................
215
The HRG survey activities will be
supported by vessels of sufficient size to
accomplish the survey goals in each of
the specified survey areas. Surveys in
each of the identified survey areas will
be executed by a single vessel during
any given campaign (i.e., no more than
one survey vessel would operate in the
Lease Area and deep-water section of
the cable route at any given time, but
there may be one survey vessel
operating in the Lease Area and deepwater cable route, one vessel in the
shallow-water section of the cable route,
and one vessel in the very shallow
waters of the cable route operating
concurrently, for a total of three vessels
conducting HRG surveys). HRG
equipment will either by mounted to or
towed behind the survey vessel at a
typical survey speed of approximately 3
knots (kn; 5.6 km per hour). The
geophysical survey activities proposed
by Mayflower would include the
following:
• Seafloor imaging (sidescan sonar)
for seabed sediment classification
purposes, to identify natural and manmade acoustic targets resting on the
seafloor. The sonar device emits conical
or fan-shaped pulses down toward the
seafloor in multiple beams at a wide
angle, perpendicular to the path of the
sensor through the water. The acoustic
return of the pulses is recorded in a
series of cross-track slices, which can be
joined to form an image of the sea
bottom within the swath of the beam.
They are typically towed beside or
behind the vessel or from an
autonomous vehicle;
• Multibeam echosounder (MBES) to
determine water depths and general
bottom topography. MBES sonar
systems project sonar pulses in several
angled beams from a transducer
mounted to a ship’s hull. The beams
radiate out from the transducer in a fanshaped pattern orthogonally to the
ship’s direction;
• Medium penetration sub-bottom
profiler (sparkers) to map deeper
subsurface stratigraphy as needed.
Sparkers create acoustic pulses from 50
Hz to 4 kHz omni-directionally from the
source that can penetrate several
hundred meters into the seafloor.
Typically towed behind the vessel with
adjacent hydrophone arrays to receive
the return signals;
• Parametric sub-bottom profiler to
provide high data density in sub-bottom
profiles that are typically required for
cable routes, very shallow water, and
archaeological surveys. Typically
mounted on the hull of the vessel or
from a side pole; and
• Ultra-short baseline (USBL)
positioning and Global Acoustic
Positioning System (GAPS) to provide
high accuracy ranges by measuring the
time between the acoustic pulses
transmitted by the vessel transceiver
and the equipment transponder
necessary to produce the acoustic
profile. It is a two-component system
with a hull or pole mounted transceiver
and one to several transponders either
on the seabed or on the equipment.
Table 2 identifies the representative
survey equipment that may be used in
support of planned geophysical survey
activities that operate below 180
kilohertz (kHz) and have the potential to
cause acoustic harassment to marine
mammals. The make and model of the
listed geophysical equipment may vary
depending on availability and the final
equipment choices will vary depending
upon the final survey design, vessel
availability, and survey contractor
selection. Geophysical surveys are
expected to use several equipment types
concurrently in order to collect multiple
aspects of geophysical data along one
transect. Selection of equipment
combinations is based on specific
survey objectives.
TABLE 2—SUMMARY OF HRG SURVEY EQUIPMENT PROPOSED FOR USE BY MAYFLOWER
Specific HRG equipment
Sparker .....................
Geomarine Geo-Spark 800 J system.
Edgetech 3100 with SB–2–16S
towfish.
Innomar SES–2000 Medium-100
Parametric.
Sub-bottom profiler ..
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Operating
frequency
range
(kHz)
HRG equipment
category
The deployment of HRG survey
equipment, including the equipment
planned for use during Mayflower’s
proposed activity, produces sound in
the marine environment that has the
potential to result in harassment of
marine mammals. Proposed mitigation,
monitoring, and reporting measures are
described in detail later in this
document (please see Proposed
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Source level
(dB rms)
Typical pulse
duration
(ms)
Beamwidth
(degrees)
Pulse
repetition rate
(Hz)
0.25 to 5 .......
203
180
3.4
2
2 to 16 ..........
179
65
10
10
85 to 115 ......
241
2
2
40
Mitigation and Proposed Monitoring and affected species. Additional information
Reporting).
regarding population trends and threats
may be found in NMFS’s Stock
Description of Marine Mammals in the
Assessment Reports (SARs; https://
Area of Specified Activities
www.fisheries.noaa.gov/national/
marine-mammal-protection/marineSections 3 and 4 of the application
mammal-stock-assessments) and more
summarize available information
regarding status and trends, distribution general information about these species
(e.g., physical and behavioral
and habitat preferences, and behavior
descriptions) may be found on NMFS’s
and life history, of the potentially
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website. (https://
www.fisheries.noaa.gov/find-species).
Table 3 lists all species or stocks for
which take is expected and proposed to
be authorized for this action, and
summarizes information related to the
population or stock, including
regulatory status under the MMPA and
ESA and potential biological removal
(PBR), where known. For taxonomy, we
follow Committee on Taxonomy (2019).
PBR is 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 (as described in NMFS’s
SARs). While no mortality is anticipated
or authorized here, PBR and annual
serious injury and mortality from
anthropogenic sources are included here
as gross indicators of the status of the
species and other threats.
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 or survey 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. All managed
stocks in this region are assessed in
NMFS’s U.S. Atlantic SARs. All values
presented in Table 3 are the most recent
available at the time of publication and
are available in the 2018 Atlantic and
Gulf of Mexico Marine Mammal Stock
Assessments (Hayes et al., 2019a),
available online at:
www.fisheries.noaa.gov/national/
marine-mammal-protection/marinemammal-stock-assessment-reportsregion or and draft 2019 Atlantic and
Gulf of Mexico Marine Mammal Stock
Assessments (Hayes et al. 2019b)
available online at: https://
www.fisheries.noaa.gov/national/
marine-mammal-protection/draftmarine-mammal-stock-assessmentreports.
TABLE 3—MARINE MAMMALS KNOWN TO OCCUR IN THE PROJECT AREA THAT MAY BE AFFECTED BY MAYFLOWER’S
PROPOSED ACTIVITY
Common name
Scientific name
ESA/
MMPA
status;
strategic
(Y/N) 1
Stock
Stock abundance
(CV, Nmin, most recent
abundance survey) 2
Predicted
abundance 3
PBR 4
Annual
M/SI 4
Order Cetartiodactyla—Cetacea—Superfamily Mysticeti (baleen whales)
Family Balaenidae:
North Atlantic right
whale.
Family Balaenopteridae
(rorquals):
Humpback whale ......
Eubalaena glacialis .........
Western North Atlantic ....
E/D; Y
428 (0; 418; n/a) .............
535 (0.45) * .....
0.9
5.56
Megaptera novaeangliae
Gulf of Maine ..................
-/-; N
1,637 (0.07) * ..
22
12.15
Fin whale .........................
Balaenoptera physalus ...
Western North Atlantic ....
E/D; Y
4,633 (0.08) ....
12
2.35
Sei whale .........................
Balaenoptera borealis .....
Nova Scotia .....................
E/D; Y
717 (0.30) * .....
6.2
1
Minke whale .....................
Balaenoptera ...................
acutorostrata ...................
Canadian East Coast ......
-/-; N
1,396 (0; 1,380; See
SAR).
7,418 (0.25; 6,029; See
SAR).
6292 (1.015; 3,098; see
SAR) 236.
24,202 (0.3; 18,902; See
SAR).
2,112 (0.05) * ..
1189
8
Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
Family Physeteridae:
Sperm whale .............
Family Delphinidae:
Long-finned pilot
whale.
Bottlenose dolphin ....
Physeter macrocephalus
NA ...................................
E; Y
4349 (0.28;3,451; See
SAR).
5,353 (0.12) ....
6.9
0
Globicephala melas ........
Western North Atlantic ....
-/-; Y
5,636 (0.63; 3,464) .........
18,977 (0.11) 5
35
38
Tursiops spp ...................
-/-; N
97,476 (0.06) 5
591
28
-/-; N
62,851 (0.23; 51,914;
See SAR).
172,825 (0.21; 145,216;
See SAR).
92,233 (0.71; 54,433;
See SAR).
35,493 (0.19; 30,289;
See SAR).
86,098 (0.12) ..
1,452
419
37,180 (0.07) ..
544
26
7,732 (0.09) ....
303
54.3
95,543 (0.31; 74,034;
See SAR).
45,089 (0.12) *
851
217
N/A ..................
1,389
5,688
N/A ..................
345
333
Common dolphin .......
Delphinus delphis ............
Western North Atlantic
Offshore.
Western North Atlantic ....
Atlantic white-sided
dolphin.
Risso’s dolphin ..........
Lagenorhynchus acutus ..
Western North Atlantic ....
-/-; N
Grampus griseus .............
Western North Atlantic ....
-/-; N
Phocoena phocoena .......
Gulf of Maine/Bay of
Fundy.
-/-; N
Family Phocoenidae (porpoises):
Harbor porpoise ........
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Order Carnivora—Superfamily Pinnipedia
Family Phocidae (earless
seals):
Gray seal 6 ................
Halichoerus grypus .........
Western North Atlantic ....
-/-; N
Harbor seal ...............
Phoca vitulina ..................
Western North Atlantic ....
¥/¥; N
27,131 (0.19; 23,158,
2016).
75,834 (0.15; 66,884,
2018).
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: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessmentreports-region/. CV is coefficient of variation; Nmin is the minimum estimate of stock abundance. In some cases, CV is not applicable
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3 This information represents species- or guild-specific abundance predicted by recent habitat-based cetacean density models (Roberts et al., 2016, 2017, 2018).
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 abundance predictions as a point of reference. Total abundance estimates were produced by computing the mean density of all pixels in the modeled
area and multiplying by its area. 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 abundance.
4 Potential biological removal, 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 size (OSP). Annual M/SI, found in NMFS’ SARs, represent annual
levels of human-caused mortality plus serious injury from all sources combined (e.g., commercial fisheries, subsistence hunting, ship strike). Annual M/SI values often
cannot be determined precisely and is in some cases presented as a minimum value. All M/SI values are as presented in the draft 2019 SARs (Hayes et al., 2019).
5 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, 2017, 2018) are based in part on available observational data which, in some cases, is limited to
genus or guild in terms of taxonomic definition. Roberts et al. (2016, 2017, 2018) produced density models to genus level for Globicephala spp. and produced a density model for bottlenose dolphins that does not differentiate between offshore and coastal stocks.
6 8 NMFS stock abundance estimate applies to U.S. population only, actual stock abundance is approximately 505,000.
As indicated above, all 14 species
(with 14 managed stocks) in Table 3
temporally and spatially co-occur with
the activity to the degree that take is
reasonably likely to occur, and we have
proposed authorizing it. All species that
could potentially occur in the proposed
survey areas are included in Table 4 of
the IHA application. However, the
temporal and/or spatial occurrence of
several species listed in Table 4 in the
IHA application is such that take of
these species is not expected to occur.
The blue whale (Balaenoptera
musculus), Cuvier’s beaked whale
(Ziphius cavirostris), four species of
Mesoplodont beaked whale
(Mesoplodon spp.), dwarf and pygmy
sperm whale (Kogia sima and Kogia
breviceps), and striped dolphin
(Stenella coeruleoalba), typically occur
further offshore than the Project Area,
while short-finned pilot whales
(Globicephala macrorhynchus) and
Atlantic spotted dolphins (Stenella
frontalis) are typically found further
south than the Project Area (Hayes et al.,
2019b). There are stranding records of
harp seals (Pagophilus groenlandicus)
in Massachusetts, but the species
typically occurs north of the Project
Area and appearances in Massachusetts
usually occur between January and May,
outside of the proposed survey dates
(Hayes et al., 2019b). As take of these
species is not anticipated as a result of
the proposed activities, these species are
not analyzed further.
The following subsections provide
additional information on the biology,
habitat use, abundance, distribution,
and the existing threats to the non-ESAlisted and ESA-listed marine mammals
that are both common in the waters of
the outer continental shelf (OCS) of
Southern New England and have the
likelihood of occurring, at least
seasonally, in the Project Area and are,
therefore, expected to potentially be
taken by the proposed activities.
North Atlantic Right Whale
The Western Atlantic stock of North
Atlantic right whales ranges primarily
from calving grounds in coastal waters
of the southeastern United States to
feeding grounds in New England waters
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and the Canadian Bay of Fundy, Scotian
Shelf, and Gulf of St. Lawrence (Hayes
et al., 2019). Surveys indicate that there
are seven areas where NARWs
congregate seasonally: The coastal
waters of the southeastern United
States, the Great South Channel, Jordan
Basin, Georges Basin along the
northeastern edge of Georges Bank, Cape
Cod and Massachusetts Bays, the Bay of
Fundy, and the Roseway Basin on the
Scotian Shelf (Hayes et al. 2018). The
closest of these seven areas is the Great
South Channel, which lies east of the
Project Area, though none of these areas
directly overlaps the Project Area.
NMFS has designated two critical
habitat areas for the NARW under the
ESA: the Gulf of Maine/Georges Bank
region, and the southeast calving
grounds from North Carolina to Florida.
NMFS’s regulations at 50 CFR part
224.105 designated nearshore waters of
the Mid-Atlantic Bight as Mid-Atlantic
U.S. Seasonal Management Areas (SMA)
for right whales in 2008. SMAs were
developed to reduce the threat of
collisions between ships and right
whales around their migratory route and
calving grounds. All vessels greater than
19.8 m (65 ft) in overall length must
operate at speeds of 10 knots (5.1 m/s)
or less within these areas during
specific time periods. The Lease Area is
located approximately 15 km southeast
of the Block Island Sound SMA, which
is active between November 1 and April
30 each year. The Great South Channel
SMA lies to the northeast of the Lease
Area and is active April 1 to July 31.
NOAA Fisheries may also establish
Dynamic Management Areas (DMAs)
when and where NARWs are sighted
outside SMAs. DMAs are generally in
effect for two weeks. During this time,
vessels are encouraged to avoid these
areas or reduce speeds to 10 knots (5.1
m/s) or less while transiting through
these areas.
LaBrecque et al. 2015 identified
‘‘biologically important areas (BIAs)’’ for
cetaceans on the U.S. East Coast,
including reproductive, feeding, and
migratory areas, as well as areas where
small and resident populations reside.
The Project Area is encompassed by a
right whale BIA for migration from
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March to April and from November to
December. A feeding BIA for right
whales from April to June was
identified northeast of the Project Area,
east of Cape Cod.
The western North Atlantic
population demonstrated overall growth
of 2.8 percent per year from 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 1 percent per year (Pace et al.
2017). Between 1990 and 2015, calving
rates varied substantially, with low
calving rates coinciding with all three
periods of decline or no growth (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. However, in 2019 at
least seven right whale calves were
identified while ten calves have been
recorded in 2020. Data indicates that the
number of adult females fell from 200 in
2010 to 186 in 2015 while males fell
from 283 to 272 in the same time period
(Pace et al., 2017). In addition, elevated
North Atlantic right whale mortalities
have occurred since June 7, 2017. A
total of 30 confirmed dead stranded
whales (21 in Canada; 9 in the United
States), have been documented to date.
This event has been declared an
Unusual Mortality Event (UME), with
human interactions (i.e., fishery-related
entanglements and vessel strikes)
identified as the most likely cause. More
information is available online at:
https://www.fisheries.noaa.gov/
national/marine-life-distress/2017-2019north-atlantic-right-whale-unusualmortality-event.
Humpback Whale
Humpback whales are found
worldwide in all oceans. Humpback
whales were listed as endangered under
the Endangered Species Conservation
Act (ESCA) in June 1970. In 1973, the
ESA replaced the ESCA, and
humpbacks continued to be listed as
endangered. NMFS recently evaluated
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the status of the species, and on
September 8, 2016, NMFS divided the
species into 14 distinct population
segments (DPS), removed the current
species-level listing, and in its place
listed four DPSs as endangered and one
DPS as threatened (81 FR 62259;
September 8, 2016). The remaining nine
DPSs were not listed. The West Indies
DPS, which is not listed under the ESA,
is the only DPS of humpback whale that
is expected to occur in the Project Area.
The best estimate of population
abundance for the West Indies DPS is
12,312 individuals, as described in the
NMFS Status Review of the Humpback
Whale under the Endangered Species
Act (Bettridge et al., 2015).
Humpback whales in the Gulf of
Maine stock typically feed in the waters
between the Gulf of Maine and
Newfoundland during spring, summer,
and fall, but have been observed feeding
in other areas, such as off the coast of
New York (Sieswerda et al. 2015).
Humpback whales are frequently
piscivorous when in New England
waters, feeding on herring (Clupea
harengus), sand lance (Ammodytes
spp.), and other small fishes, as well as
euphausiids in the northern Gulf of
Maine (Paquet et al. 1997). During
winter, the majority of humpback
whales from North Atlantic feeding
areas (including the Gulf of Maine) mate
and calve in the West Indies, where
spatial and genetic mixing among
feeding groups occurs, though
significant numbers of animals are
found in mid- and high-latitude regions
at this time and some individuals have
been sighted repeatedly within the same
winter season, indicating that not all
humpback whales migrate south every
winter (Waring et al., 2017).
Kraus et al. (2016) observed
humpback whales in the RI/MA & MA
WEAs and surrounding areas during all
seasons. Humpback whales were
observed most often during spring and
summer months, with a peak from April
to June. Calves were observed 10 times
and feeding was observed 10 times
during the Kraus et al. (2016) study.
That study also observed one instance of
courtship behavior. Although humpback
whales were rarely seen during fall and
winter surveys, acoustic data indicate
that this species may be present within
the Massachusetts Wind Energy Area
(WEA) year-round, with the highest
rates of acoustic detections in winter
and spring (Kraus et al. 2016).
A humpback whale BIA for feeding
has been identified northeast of the
Lease Area in the Gulf of Maine,
Stellwagen Bank, and the Great South
Channel from March through December
(LaBrecque et al., 2015).
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Since January 2016, elevated
humpback whale mortalities have
occurred along the Atlantic coast from
Maine through Florida. The event has
been declared a UME. Partial or full
necropsy examinations have been
conducted on approximately half of the
111 known cases. A portion of the
whales have shown evidence of premortem vessel strike; however, this
finding is not consistent across all of the
whales examined so 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. More
detailed information is available at:
https://www.fisheries.noaa.gov/
national/marine-life-distress/2016-2019humpback-whale-unusual-mortalityevent-along-atlantic-coast (accessed
January 9, 2020). Three previous UMEs
involving humpback whales have
occurred since 2000, in 2003, 2005, and
2006.
Fin Whale
The fin whale is the second largest
baleen whale and is widely distributed
in all the world’s oceans, but is most
abundant in temperate and cold waters
(Aguilar and Garcı´a-Vernet 2018). Fin
whales are presumed to migrate
seasonally between feeding and
breeding grounds, but their migrations
are less well defined than for other
baleen whales. In the North Atlantic,
some feeding areas have been identified
but there are no known wintering areas
(Aguilar and Garcı´a-Vernet 2018). Fin
whales are found in the summer from
Baffin Bay, Spitsbergen, and the Barents
Sea south to North Carolina and the
coast of Portugal (Rice 1998).
Apparently not all individuals migrate,
because in winter they have been
sighted from Newfoundland to the Gulf
of Mexico and the Caribbean Sea, and
from the Faroes and Norway south to
the Canary Islands (Rice 1998). Fin
whales off the eastern United States,
Nova Scotia, and the southeastern coast
of Newfoundland are believed to
constitute a single stock under the
present International Whaling
Commission (IWC) management scheme
(Donovan 1991), which has been called
the Western North Atlantic stock.
Kraus et al. (2016) suggest that,
compared to other baleen whale species,
fin whales have a high multi-seasonal
relative abundance in the Rhode Island/
Massachusetts and Massachusetts Wind
Energy Areas (RI/MA & MA WEAs) and
surrounding areas. Fin whales were
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observed in the MA WEA) in spring and
summer. This species was observed
primarily in the offshore (southern)
regions of the RI/MA & MA WEAs
during spring and was found closer to
shore (northern areas) during the
summer months (Kraus et al. 2016).
Calves were observed three times and
feeding was observed nine times during
the Kraus et al. (2016) study. Although
fin whales were largely absent from
visual surveys in the RI/MA & MA
WEAs in the fall and winter months
(Kraus et al. 2016), acoustic data
indicated that this species was present
in the RI/MA & MA WEAs during all
months of the year.
The main threats to fin whales are
fishery interactions and vessel collisions
(Waring et al., 2017). New England
waters represent a major feeding ground
for fin whales. The Lease Area is
flanked by two BIAs for feeding fin
whales—the area to the northeast is
considered a BIA year-round, while the
area off the tip of Long Island to the
southwest is a BIA from March to
October (LaBrecque et al. 2015).
Sei Whale
Sei whales occur worldwide, with a
preference for oceanic waters over shelf
waters (Horwood 2018). The Nova
Scotia stock of sei whales can be found
in deeper waters of the continental shelf
edge waters of the northeastern United
States and northeastward to south of
Newfoundland. NOAA Fisheries
considers sei whales occurring from the
U.S. East Coast to Cape Breton, Nova
Scotia, and east to 42° W as the Nova
Scotia stock of sei whales (Waring et al.
2016; Hayes et al. 2018). In the
Northwest Atlantic, it is speculated that
the whales migrate from south of Cape
Cod along the eastern Canadian coast in
June and July, and return on a
southward migration again in
September and October (Waring et al.
2014; 2017).
Spring is the period of greatest
abundance in U.S. waters, with
sightings concentrated along the eastern
margin of Georges Bank and into the
Northeast Channel area, and along the
southwestern edge of Georges Bank in
the area of Hydrographer Canyon
(Waring et al., 2015). Kraus et al. (2016)
observed sei whales in the RI/MA and
MA WEAs and surrounding areas only
between the months of March and June
during the 2011–2015 NLPSC aerial
survey. The number of sei whale
observations was less than half that of
other baleen whale species in the two
seasons in which sei whales were
observed (spring and summer). This
species demonstrated a distinct seasonal
habitat use pattern that was consistent
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throughout the study. Calves were
observed three times and feeding was
observed four times during the Kraus et
al. (2016) study. Sei whales were not
observed in the MA WEA and nearby
waters during the 2010–2017 Atlantic
Marine Assessment Program for
Protected Species (AMAPPS) shipboard
and aerial surveys. However, there were
observations during the 2016 and 2017
summer surveys that were identified as
being either a fin or sei whale. A BIA
for feeding for sei whales occurs east of
the Lease Area from May through
November (LaBrecque et al. 2015).
Minke Whale
Minke whales have a cosmopolitan
distribution that spans ice-free latitudes
(Stewart and Leatherwood 1985). The
Canadian East Coast stock can be found
in the area from the western half of the
Davis Strait (45 °W) to the Gulf of
Mexico (Waring et al., 2017). This
species generally occupies waters less
than 100 m deep on the continental
shelf. There appears to be a strong
seasonal component to minke whale
distribution in which spring to fall are
times of relatively widespread and
common occurrence, and when the
whales are most abundant in New
England waters, while during winter the
species appears to be largely absent
(Waring et al., 2017).
Kraus et al. (2016) observed minke
whales in the RI/MA & MA WEAs and
surrounding areas primarily from May
to June. This species demonstrated a
distinct seasonal habitat usage pattern
that was consistent throughout the
study. Though minke whales were
observed in spring and summer months
in the MA WEA, they were only
observed in the lease areas in the spring.
Minke whales were not observed
between October and February, but
acoustic data indicate the presence of
this species in the proposed Project
Area in winter months. A BIA for
feeding for minke whales occurs east of
the Lease Area from March through
November (LaBrecque et al., 2015).
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.
Partial or full necropsy examinations
have been conducted on more than 60
percent of the 79 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. More information is available
at: https://www.fisheries.noaa.gov/
national/marine-life-distress/2017-2019-
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Sperm Whale
The distribution of the sperm whale
in the U.S. Exclusive Economic Zone
(EEZ) occurs on the continental shelf
edge, over the continental slope, and
into mid-ocean regions (Waring et al.
2015). The basic social unit of the sperm
whale appears to be the mixed school of
adult females plus their calves and some
juveniles of both sexes, normally
numbering 20–40 animals in all. Sperm
whales are somewhat migratory;
however, their migrations are not as
specific as seen in most of the baleen
whale species. In the North Atlantic,
there appears to be a general shift
northward during the summer, but there
is no clear migration in some temperate
areas (Rice 1989). In summer, the
distribution of sperm whales includes
the area east and north of Georges Bank
and into the Northeast Channel region,
as well as the continental shelf (inshore
of the 100-m isobath) south of New
England. In the fall, sperm whale
occurrence south of New England on the
continental shelf is at its highest level,
and there remains a continental shelf
edge occurrence in the mid-Atlantic
bight. In winter, sperm whales are
concentrated east and northeast of Cape
Hatteras. Their distribution is typically
associated with waters over the
continental shelf break and the
continental slope and into deeper
waters (Whitehead et al. 1991). Sperm
whale concentrations near drop-offs and
areas with strong currents and steep
topography are correlated with high
productivity. These whales occur almost
exclusively found at the shelf break,
regardless of season.
Kraus et al. (2016) observed sperm
whales four times in the RI/MA & MA
WEAs during the summer and fall from
2011 to 2015. Sperm whales, traveling
singly or in groups of three or four, were
observed three times in August and
September of 2012, and once in June of
2015.
Long-Finned Pilot Whale
Long-finned pilot whales are found
from North Carolina and north to
Iceland, Greenland and the Barents Sea
(Waring et al., 2016). They are generally
found along the edge of the continental
shelf (a depth of 330 to 3,300 feet (100
to 1,000 meters)), choosing areas of high
relief or submerged banks in cold or
temperate shoreline waters. In the
western North Atlantic, long-finned
pilot whales are pelagic, occurring in
especially high densities in winter and
spring over the continental slope, then
moving inshore and onto the shelf in
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summer and autumn following squid
and mackerel populations (Reeves et al.
2002). They frequently travel into the
central and northern Georges Bank,
Great South Channel, and Gulf of Maine
areas during the late spring and remain
through early fall (May and October)
(Payne and Heinemann 1993).
Note that long-finned and shortfinned pilot whales overlap spatially
along the mid-Atlantic shelf break
between New Jersey and the southern
flank of Georges Bank (Payne and
Heinemann 1993, Hayes et al. 2017)
Long-finned pilot whales have
occasionally been observed stranded as
far south as South Carolina, and shortfinned pilot whale have stranded as far
north as Massachusetts (Hayes et al.
2017). The latitudinal ranges of the two
species therefore remain uncertain.
However, south of Cape Hatteras, most
pilot whale sightings are expected to be
short-finned pilot whales, while north
of approximately 42° N, most pilot
whale sightings are expected to be longfinned pilot whales (Hayes et al. 2017).
Based on the distributions described in
Hayes et al. (2017), pilot whale sightings
in the Project Area would most likely be
long-finned pilot whales.
Kraus et al. (2016) observed pilot
whales infrequently in the RI/MA & MA
WEAs and surrounding areas. Effortweighted average sighting rates for pilot
whales could not be calculated. No pilot
whales were observed during the fall or
winter, and these species were only
observed 11 times in the spring and
three times in the summer.
Atlantic White-Sided Dolphin
White-sided dolphins are found in
cold temperate and sub-polar waters of
the North Atlantic, primarily in
continental shelf waters to the 100-m
depth contour from central West
Greenland to North Carolina (Waring et
al., 2017). The Gulf of Maine stock is
most common in continental shelf
waters from Hudson Canyon to Georges
Bank, and in the Gulf of Maine and
lower Bay of Fundy. Sighting data
indicate seasonal shifts in distribution
(Northridge et al., 1997). During January
to May, low numbers of white-sided
dolphins are found from Georges Bank
to Jeffreys Ledge (off New Hampshire),
with even lower numbers south of
Georges Bank, as documented by a few
strandings collected on beaches of
Virginia to South Carolina. From June
through September, large numbers of
white-sided dolphins are found from
Georges Bank to the lower Bay of
Fundy. From October to December,
white-sided dolphins occur at
intermediate densities from southern
Georges Bank to southern Gulf of Maine
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(Payne and Heinemann 1990). Sightings
south of Georges Bank, particularly
around Hudson Canyon, occur year
round but at low densities.
Kraus et al. (2016) suggest that
Atlantic white-sided dolphins occur
infrequently in the RI/MA & MA WEAs
and surrounding areas. Effort-weighted
average sighting rates for Atlantic whitesided dolphins could not be calculated,
because this species was only observed
on eight occasions throughout the
duration of the study (October 2011 to
June 2015). No Atlantic white-sided
dolphins were observed during the
winter months, and this species was
only sighted twice in the fall and three
times in the spring and summer.
Common Dolphin
The common dolphin is one of the
most abundant and widely distributed
cetaceans, occurring in warm temperate
and tropical regions worldwide from
about 60° N to 50° S (Perrin 2018).
These dolphins occur in groups of
hundreds or thousands of individuals
and often associate with pilot whales or
other dolphin species (Perrin 2018).
Until recently, short-beaked and longbeaked common dolphins were thought
to be separate species but evidence now
suggests that this character distinction is
based on ecology rather than genetics
(Perrin 2018) and the Committee on
Taxonomy now recognizes a single
species with three subspecies of
common dolphin. The common
dolphins occurring in the Project Area
are expected to be short-beaked
common dolphins (Delphinus delphis
delphis; Perrin 2018) and would belong
to the Western North Atlantic stock
(Hayes et al., 2018).
In the North Atlantic, short-beaked
common dolphins are commonly found
over the continental shelf between the
100-m and 2,000-m isobaths and over
prominent underwater topography and
east to the mid-Atlantic Ridge (Waring
et al., 2016). This species is found
between Cape Hatteras and Georges
Bank from mid-January to May,
although they migrate onto the northeast
edge of Georges Bank in the fall where
large aggregations occur (Kenney and
Vigness-Raposa 2009), where large
aggregations occur on Georges Bank in
fall (Waring et al. 2007).
Kraus et al. (2016) suggested that
short-beaked common dolphins occur
year-round in the RI/MA & MA WEAs
and surrounding areas. Short-beaked
common dolphins were the most
frequently observed small cetacean
species within the Kraus et al. (2016)
study area. Short-beaked common
dolphins were observed in the RI/MA &
MA WEAs in all seasons but were most
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frequently observed during the summer
months, with peak sightings in June and
August. Short-beaked common dolphins
were observed in the MA WEA and
nearby waters during all seasons of the
2010–2017 AMAPPS surveys.
Bottlenose Dolphin
There are two distinct bottlenose
dolphin ecotypes in the western North
Atlantic: the coastal and offshore forms
(Waring et al., 2015). The migratory
coastal morphotype resides in waters
typically less than 65.6 ft (20 m) deep,
along the inner continental shelf (within
7.5 km (4.6 miles) of shore), around
islands, and is continuously distributed
south of Long Island, New York into the
Gulf of Mexico. This migratory coastal
population is subdivided into 7 stocks
based largely upon spatial distribution
(Waring et al. 2015). Generally, the
offshore migratory morphotype is found
exclusively seaward of 34 km (21 miles)
and in waters deeper than 34 m (111.5
feet). This morphotype is most expected
in waters north of Long Island, New
York (Waring et al. 2017; Hayes et al.
2017; 2018). Bottlenose dolphins
encountered in the Project Area would
likely belong to the Western North
Atlantic Offshore stock (Hayes et al.
2018). It is possible that a few animals
could be from the Northern Migratory
Coastal stock, but they generally do not
range farther north than New Jersey.
Kraus et al. (2016) observed common
bottlenose dolphins during all seasons
within the RI/MA & MA WEAs.
Common bottlenose dolphins were the
second most commonly observed small
cetacean species and exhibited little
seasonal variability in abundance.
Common bottlenose dolphins were
observed in the MA WEA and nearby
waters during spring, summer, and fall
of the 2010–2017 AMAPPS surveys.
Risso’s Dolphins
Risso’s dolphins are distributed
worldwide in tropical and temperate
seas (Jefferson et al., 2008, 2014), and in
the Northwest Atlantic occur from
Florida to eastern Newfoundland
(Leatherwood et al. 1976; Baird and
Stacey 1991). Off the northeastern U.S.
coast, Risso’s dolphins are distributed
along the continental shelf edge from
Cape Hatteras northward to Georges
Bank during spring, summer, and
autumn (CETAP 1982; Payne et al.,
1984). In winter, the range is in the midAtlantic Bight and extends outward into
oceanic waters (Payne et al., 1984).
Risso’s dolphins appear to prefer
steep sections of the continental shelf
edge and deep offshore waters 100–
1,000 m deep (Hartman 2018). They are
deep divers, feeding primarily on deep
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mesopelagic cephalopods such as squid,
octopus, and cuttlefish, and likely
forage at night (Hartman 2018).
Kraus et al. (2016) results suggest that
Risso’s dolphins occur infrequently in
the RI/MA & MA WEAs and
surrounding areas. Risso’s dolphins
were observed in the MA WEA and
nearby waters during spring and
summer of the 2010–2017 AMAPPS
surveys.
Harbor Porpoise
The harbor porpoise inhabits cool
temperate to subarctic waters of the
Northern Hemisphere, generally within
shallow coastal waters of the
continental shelf but occasionally travel
over deeper, offshore waters (Jefferson et
al., 2008). They are usually seen in
small groups of one to three but
occasionally form much larger groups
(Bj1800 m; Westgate et al. 1998),
although the majority of the population
is found over the continental shelf
(Waring et al., 2017).
Kraus et al. (2016) indicate that
harbor porpoises occur within the RI/
MA & MA WEAs in fall, winter, and
spring. Harbor porpoises were observed
in groups ranging in size from three to
15 individuals and were primarily
observed in the Kraus et al. (2016) study
area from November through May, with
very few sightings during June through
September. Harbor porpoises were
observed in the MA WEA and nearby
waters during spring and fall of the
2010–2017 AMAPPS surveys.
Harbor Seal
The harbor seal has a wide
distribution throughout coastal waters
between 30° N and ∼80° N (Teilmann
and Galatius 2018). Harbor seals are
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year-round inhabitants of the coastal
waters of eastern Canada and Maine
(Katona et al. 1993), and occur
seasonally along the coasts from
southern New England to New Jersey
from September through late May
(Barlas 1999; Katona et al., 1993;
Schneider and Payne 1983; Schroeder
2000). A northward movement from
southern New England to Maine and
eastern Canada occurs prior to the
pupping season, which takes place from
mid-May through June (Kenney 1994;
Richardson 1976; Whitman and Payne
1990; Wilson 1978). Harbor seals are
generally present in the Project Area
seasonally, from September through
May (Hayes et al., 2019).
Kraus et al. (2016) observed harbor
seals in the RI/MA and MA WEAs and
surrounding areas during the 2011–2015
NLPSC aerial survey, but this survey
was designed to target large cetaceans so
locations and numbers of seal
observations were not included in the
study report. Harbor seals have five
major haulout sites in and near the RI/
MA and MA WEAs: Monomoy Island,
the northwestern side of Nantucket
Island, Nomans Land, the north side of
Gosnold Island, and the southeastern
side of Naushon Island (Payne and
Selzer 1989). Harbor seals were
observed in the MA WEA and nearby
waters during spring, summer, and fall
of the 2010–2017 AMAPPS surveys.
Gray Seal
Gray seals are found throughout the
temperate and subarctic waters of the
North Atlantic (King 1983). In the
northwestern Atlantic, they occur from
Labrador sound to Massachusetts (King
1983). Gray seals often haul out on
remote, exposed islands, shoals, and
unstable sandbars (Jefferson et al.,
2008). Though they spend most of their
time in coastal waters, gray seals can
dive to depths of 300 m (984 ft) and
frequently forage on the outer
continental shelf (Jefferson et al., 2008).
Gray seals in the Project Area belong
to the western North Atlantic stock. The
range for this stock is thought to be from
New Jersey to Labrador. Current
population trends show that gray seal
abundance is likely increasing in the
U.S. Atlantic EEZ (Waring et al., 2017).
Although the rate of increase is
unknown, surveys conducted since their
arrival in the 1980s indicate a steady
increase in abundance in both Maine
and Massachusetts (Waring et al., 2017).
It is believed that recolonization by
Canadian gray seals is the source of the
U.S. population (Waring et al., 2017). In
U.S. waters, gray seals currently pup at
four established colonies from late
December to mid-February: Muskeget
and Monomoy Islands in Massachusetts,
and Green and Seal Islands in Maine
(Hayes et al., 2019). Pupping was also
observed in the early 1980s on small
islands in Nantucket-Vineyard Sound
and since 2010, pupping has been
documented at Nomans Island in
Massachusetts (Hayes et al., 2019). The
distributions of individuals from
different breeding colonies overlap
outside of the breeding season. Gray
seals may be present in the Project Area
year-round (Hayes et al., 2018).
Since July 2018, elevated numbers of
harbor seal and gray seal mortalities
have occurred across Maine, New
Hampshire and Massachusetts. This
event has been declared a UME.
Additionally, seals showing clinical
signs of stranding have occurred as far
south as Virginia, although not in
elevated numbers. Therefore the UME
investigation now encompasses all seal
strandings from Maine to Virginia.
Between July 1, 2018 and March 13,
2020, a total of 3,152 seal strandings
have been recorded as part of this
designated Northeast Pinniped UME.
Based on tests conducted so far, the
main pathogen found in the seals is
phocine distemper virus. Additional
testing to identify other factors that may
be involved in this UME are underway.
More information is available at: https://
www.fisheries.noaa.gov/new-englandmid-atlantic/marine-life-distress/20182020-pinniped-unusual-mortality-eventalong.
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). Subsequently, NMFS (2018)
described generalized hearing ranges for
these marine mammal hearing groups.
Generalized hearing ranges were chosen
based on the approximately 65 decibel
(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. Marine
mammal hearing groups and their
associated hearing ranges are provided
in Table 4.
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TABLE 4—MARINE MAMMAL HEARING GROUPS (NMFS, 2018)
Hearing group
Generalized hearing
range *
Low-frequency (LF) cetaceans (baleen whales) .........................................................................................................................
Mid-frequency (MF) cetaceans (dolphins, toothed whales, beaked whales, bottlenose whales) ..............................................
High-frequency (HF) cetaceans (true porpoises, Kogia, river dolphins, cephalorhynchid, Lagenorhynchus cruciger & L.
australis).
Phocid pinnipeds (PW) (underwater) (true seals) .......................................................................................................................
Otariid pinnipeds (OW) (underwater) (sea lions and fur seals) ..................................................................................................
7 Hz to 35 kHz.
150 Hz to 160 kHz.
275 Hz to 160 kHz.
50 Hz to 86 kHz.
60 Hz to 39 kHz.
* Represents the generalized hearing range for the entire group as a composite (i.e., all species within the group), where individual species’
hearing ranges are typically not as broad. Generalized hearing range chosen based on ∼65 dB threshold from normalized composite audiogram,
with the exception for lower limits for LF cetaceans (Southall et al. 2007) and PW pinniped (approximation).
The pinniped functional hearing
group was modified from Southall et al.
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(2007) on the basis of data indicating
that phocid species have consistently
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range of hearing compared to otariids,
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especially in the higher frequency range
(Hemila¨ et al., 2006; Kastelein et al.,
2009; Reichmuth and Holt, 2013).
For more detail concerning these
groups and associated frequency ranges,
please see NMFS (2018) for a review of
available information. Fourteen marine
mammal species (12 cetacean and two
pinniped (both phocid) species) have
the reasonable potential to co-occur
with the proposed survey activities. Of
the cetacean species that may be
present, six are classified as lowfrequency cetaceans (i.e., all mysticete
species), five are classified as midfrequency cetaceans (i.e., all delphinid
and ziphiid species and the sperm
whale), and one is classified as highfrequency cetaceans (i.e., harbor
porpoise).
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Potential Effects of Specified Activities
on Marine Mammals and Their Habitat
This section includes a summary and
discussion of the ways that components
of the specified activity may impact
marine mammals and their habitat. The
Estimated Take by Incidental
Harassment 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 Analysis
and Determination section considers the
content of this section, the Estimated
Take by Incidental Harassment section,
and the Proposed Mitigation section, to
draw conclusions regarding the likely
impacts of these activities on the
reproductive success or survivorship of
individuals and how those impacts on
individuals are likely to impact marine
mammal species or stocks.
Description of Sound Sources
This section contains a brief technical
background on sound, on the
characteristics of certain sound types,
and on metrics used in this 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. For
general information on sound and its
interaction with the marine
environment, please see, e.g., Au and
Hastings (2008); Richardson et al.
(1995).
Sound travels in waves, the basic
components of which are frequency,
wavelength, velocity, and amplitude.
Frequency is the number of pressure
waves that pass by a reference point per
unit of time and is measured in hertz
(Hz) or cycles per second. Wavelength is
the distance between two peaks or
corresponding points of a sound wave
(length of one cycle). Higher frequency
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sounds have shorter wavelengths than
lower frequency sounds, and typically
attenuate (decrease) more rapidly,
except in certain cases in shallower
water. Amplitude is the height of the
sound pressure wave or the ‘‘loudness’’
of a sound and 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 (mPa)), and is a
logarithmic unit that accounts for large
variations in amplitude; therefore, a
relatively small change in dB
corresponds to large changes in sound
pressure. 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. Root mean
square is calculated by squaring all of
the sound amplitudes, averaging the
squares, and then taking the square root
of the average. Root mean square
accounts for both positive and negative
values; squaring the pressures makes all
values positive so that they may be
accounted for in the summation of
pressure levels (Hastings and Popper,
2005). 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 in a stated frequency
band over a stated time interval or
event, and considers both intensity and
duration of exposure. The per-pulse SEL
is calculated over the time window
containing the entire pulse (i.e., 100
percent of the acoustic energy). SEL is
a cumulative metric; it can be
accumulated over a single pulse, or
calculated over periods containing
multiple pulses. Cumulative SEL
represents the total energy accumulated
by a receiver over a defined time
window or during an event. Peak sound
pressure (also referred to as zero-to-peak
sound pressure or 0-pk) 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.
When underwater objects vibrate or
activity occurs, sound-pressure waves
are created. These waves alternately
compress and decompress the water as
the sound wave travels. Underwater
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sound waves radiate in a manner similar
to ripples on the surface of a pond and
may be either directed in a beam or
beams or may radiate in all directions
(omnidirectional sources). The
compressions and decompressions
associated with sound waves are
detected as changes in pressure by
aquatic life and man-made sound
receptors such as hydrophones.
Even in the absence of sound from the
specified activity, the underwater
environment is typically loud due to
ambient sound, which is defined as
environmental background sound levels
lacking a single source or point
(Richardson et al., 1995). The sound
level of a region is defined by the total
acoustical energy being generated by
known and unknown sources. These
sources may include physical (e.g.,
wind and waves, earthquakes, ice,
atmospheric sound), biological (e.g.,
sounds produced by marine mammals,
fish, and invertebrates), and
anthropogenic (e.g., vessels, dredging,
construction) sound. A number of
sources contribute to ambient sound,
including wind and waves, which are a
main source of naturally occurring
ambient sound for frequencies between
200 hertz (Hz) and 50 kilohertz (kHz)
(Mitson, 1995). In general, ambient
sound levels tend to increase with
increasing wind speed and wave height.
Precipitation can become an important
component of total sound at frequencies
above 500 Hz, and possibly down to 100
Hz during quiet times. Marine mammals
can contribute significantly to ambient
sound levels, as can some fish and
snapping shrimp. The frequency band
for biological contributions is from
approximately 12 Hz to over 100 kHz.
Sources of ambient sound related to
human activity include transportation
(surface vessels), dredging and
construction, oil and gas drilling and
production, geophysical surveys, sonar,
and explosions. Vessel noise typically
dominates the total ambient sound for
frequencies between 20 and 300 Hz. In
general, the frequencies of
anthropogenic sounds are below 1 kHz
and, if higher frequency sound levels
are created, they attenuate rapidly.
The sum of the various natural and
anthropogenic sound sources that
comprise ambient sound at any given
location and time depends not only on
the source levels (as determined by
current weather conditions and levels of
biological and human activity) but also
on the ability of sound to propagate
through the environment. In turn, sound
propagation is dependent on the
spatially and temporally varying
properties of the water column and sea
floor, and is frequency-dependent. As a
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result of the dependence on a large
number of varying factors, ambient
sound levels can be expected to vary
widely over both coarse and fine spatial
and temporal scales. Sound levels at a
given frequency and location can vary
by 10–20 dB from day to day
(Richardson et al., 1995). The result is
that, depending on the source type and
its intensity, sound from the specified
activity may be a negligible addition to
the local environment or could form a
distinctive signal that may affect marine
mammals.
Sounds are often considered to fall
into one of two general types: Pulsed
and non-pulsed. The distinction
between these two sound types is
important because they have differing
potential to cause physical effects,
particularly with regard to hearing (e.g.,
Ward, 1997 in Southall et al., 2007).
Please see Southall et al. (2007) for an
in-depth discussion of these concepts.
The distinction between these two
sound types is not always obvious, as
certain signals share properties of both
pulsed and non-pulsed sounds. A signal
near a source could be categorized as a
pulse, but due to propagation effects as
it moves farther from the source, the
signal duration becomes longer (e.g.,
Greene and Richardson, 1988).
Pulsed sound sources (e.g., airguns,
explosions, gunshots, sonic booms,
impact pile driving) 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.
Non-pulsed sounds can be tonal,
narrowband, or broadband, brief or
prolonged, and may be either
continuous or intermittent (ANSI, 1995;
NIOSH, 1998). Some of these nonpulsed sounds can be transient signals
of short duration but without the
essential properties of pulses (e.g., rapid
rise time). Examples of non-pulsed
sounds include those produced by
vessels, aircraft, machinery operations
such as drilling or dredging, vibratory
pile driving, and active sonar systems.
The duration of such sounds, as
received at a distance, can be greatly
extended in a highly reverberant
environment.
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Potential Effects of Underwater Sound
For study-specific citations, please see
that work. Anthropogenic sounds cover
a broad range of frequencies and sound
levels and can have a range of highly
variable impacts on marine life, from
none or minor to potentially severe
responses, depending on received
levels, duration of exposure, behavioral
context, and various other factors. The
potential effects of underwater sound
from active acoustic sources can
potentially result in one or more of the
following: temporary or permanent
hearing impairment, non-auditory
physical or physiological effects,
behavioral disturbance, stress, and
masking (Richardson et al., 1995;
Gordon et al., 2004; Nowacek et al.,
2007; Southall et al., 2007; Go¨tz et al.,
2009). The degree of effect is
intrinsically related to the signal
characteristics, received level, distance
from the source, and duration of the
sound exposure. In general, sudden,
high level sounds can cause hearing
loss, as can longer exposures to lower
level sounds. Temporary or permanent
loss of hearing will occur almost
exclusively for noise within an animal’s
hearing range.
Richardson et al. (1995) described
zones of increasing intensity of effect
that might be expected to occur, in
relation to distance from a source and
assuming that the signal is within an
animal’s hearing range. First is the area
within which the acoustic signal would
be audible (potentially perceived) to the
animal but not strong enough to elicit
any overt behavioral or physiological
response. The next zone corresponds
with the area where the signal is audible
to the animal and of sufficient intensity
to elicit behavioral or physiological
responsiveness. Third is a zone within
which, for signals of high intensity, the
received level is sufficient to potentially
cause discomfort or tissue damage to
auditory or other systems. Overlaying
these zones to a certain extent is the
area within which masking (i.e., when a
sound interferes with or masks the
ability of an animal to detect a signal of
interest that is above the absolute
hearing threshold) may occur; the
masking zone may be highly variable in
size.
We describe the more severe effects
(i.e., certain non-auditory physical or
physiological effects) only briefly as we
do not expect that there is a reasonable
likelihood that HRG surveys may result
in such effects (see below for further
discussion). Potential effects from
impulsive sound sources can range in
severity from effects such as behavioral
disturbance or tactile perception to
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physical discomfort, slight injury of the
internal organs and the auditory system,
or mortality (Yelverton et al., 1973).
Non-auditory physiological effects or
injuries that theoretically might occur in
marine mammals exposed to high level
underwater sound or as a secondary
effect of extreme behavioral reactions
(e.g., change in dive profile as a result
of an avoidance reaction) caused by
exposure to sound include neurological
effects, bubble formation, resonance
effects, and other types of organ or
tissue damage (Cox et al., 2006; Southall
et al., 2007; Zimmer and Tyack, 2007;
Tal et al., 2015). The activities
considered here do not involve the use
of devices such as explosives or midfrequency tactical sonar that are
associated with these types of effects.
Threshold Shift—Note that, in the
following discussion, we refer in many
cases to a review article concerning
studies of noise-induced hearing loss
conducted from 1996–2015 (i.e.,
Finneran, 2015). Marine mammals
exposed to high-intensity sound, or to
lower-intensity sound for prolonged
periods, can experience hearing
threshold shift (TS), which is the loss of
hearing sensitivity at certain frequency
ranges (Finneran, 2015). TS can be
permanent (PTS), in which case the loss
of hearing sensitivity is not fully
recoverable, or temporary (TTS), in
which case the animal’s hearing
threshold would recover over time
(Southall et al., 2007). Repeated sound
exposure that leads to TTS could cause
PTS. In severe cases of PTS, there can
be total or partial deafness, while in
most cases the animal has an impaired
ability to hear sounds in specific
frequency ranges (Kryter, 1985).
When PTS occurs, there is physical
damage to the sound receptors in the ear
(i.e., tissue damage), whereas TTS
represents primarily tissue fatigue and
is reversible (Southall et al., 2007). In
addition, other investigators have
suggested that TTS is within the normal
bounds of physiological variability and
tolerance and does not represent
physical injury (e.g., Ward, 1997).
Therefore, NMFS does not consider TTS
to constitute auditory injury.
Relationships between TTS and PTS
thresholds have not been studied in
marine mammals, and there is no PTS
data for cetaceans, but such
relationships are assumed to be similar
to those in humans and other terrestrial
mammals. PTS typically occurs at
exposure levels at least several decibels
above (a 40-dB threshold shift
approximates PTS onset; e.g., Kryter et
al., 1966; Miller, 1974) that inducing
mild TTS (a 6-dB threshold shift
approximates TTS onset; e.g., Southall
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et al. 2007). Based on data from
terrestrial mammals, a precautionary
assumption is that the PTS thresholds
for impulse sounds (such as impact pile
driving pulses as received close to the
source) are at least 6 dB higher than the
TTS threshold on a peak-pressure basis
and PTS cumulative sound exposure
level thresholds are 15 to 20 dB higher
than TTS cumulative sound exposure
level thresholds (Southall et al., 2007).
Given the higher level of sound or
longer exposure duration necessary to
cause PTS as compared with TTS, it is
considerably less likely that PTS could
occur.
TTS is the mildest form of hearing
impairment that can occur during
exposure to sound (Kryter, 1985). While
experiencing TTS, the hearing threshold
rises, and a sound must be at a higher
level in order to be heard. In terrestrial
and marine mammals, TTS can last from
minutes or hours to days (in cases of
strong TTS). In many cases, hearing
sensitivity recovers rapidly after
exposure to the sound ends. Few data
on sound levels and durations necessary
to elicit mild TTS have been obtained
for marine mammals.
Marine mammal hearing plays a
critical role in communication with
conspecifics, and interpretation of
environmental cues for purposes such
as predator avoidance and prey capture.
Depending on the degree (elevation of
threshold in dB), duration (i.e., recovery
time), and frequency range of TTS, and
the context in which it is experienced,
TTS can have effects on marine
mammals ranging from discountable to
serious. For example, a marine mammal
may be able to readily compensate for
a brief, relatively small amount of TTS
in a non-critical frequency range that
occurs during a time where ambient
noise is lower and there are not as many
competing sounds present.
Alternatively, a larger amount and
longer duration of TTS sustained during
time when communication is critical for
successful mother/calf interactions
could have more serious impacts.
Currently, TTS data only exist for four
species of cetaceans (bottlenose
dolphin, beluga whale (Delphinapterus
leucas), harbor porpoise, and Yangtze
finless porpoise (Neophocoena
asiaeorientalis)) and three species of
pinnipeds (northern elephant seal
(Mirounga angustirostris), harbor seal,
and California sea lion (Zalophus
californianus)) exposed to a limited
number of sound sources (i.e., mostly
tones and octave-band noise) in
laboratory settings (Finneran, 2015).
TTS was not observed in trained spotted
(Phoca largha) and ringed (Pusa
hispida) seals exposed to impulsive
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noise at levels matching previous
predictions of TTS onset (Reichmuth et
al., 2016). In general, harbor seals and
harbor porpoises have a lower TTS
onset than other measured pinniped or
cetacean species (Finneran, 2015).
Additionally, the existing marine
mammal TTS data come from a limited
number of individuals within these
species. There are no data available on
noise-induced hearing loss for
mysticetes. For summaries of data on
TTS in marine mammals or for further
discussion of TTS onset thresholds,
please see Southall et al. (2007),
Finneran and Jenkins (2012), Finneran
(2015), and NMFS (2018).
Animals in the Project Area during
the proposed survey are unlikely to
incur TTS due to the characteristics of
the sound sources, which include
relatively low source levels and
generally very short pulses and duration
of the sound. Even for high-frequency
cetacean species (e.g., harbor porpoises),
which may have increased sensitivity to
TTS (Lucke et al., 2009; Kastelein et al.,
2012b), individuals would have to make
a very close approach and also remain
very close to vessels operating these
sources in order to receive multiple
exposures at relatively high levels, as
would be necessary to cause TTS.
Intermittent exposures—as would occur
due to the brief, transient signals
produced by these sources—require a
higher cumulative SEL to induce TTS
than would continuous exposures of the
same duration (i.e., intermittent
exposure results in lower levels of TTS)
(Mooney et al., 2009a; Finneran et al.,
2010). Moreover, most marine mammals
would more likely avoid a loud sound
source rather than swim in such close
proximity as to result in TTS. Kremser
et al. (2005) noted that the probability
of a cetacean swimming through the
area of exposure when a sub-bottom
profiler emits a pulse is small—because
if the animal was in the area, it would
have to pass the transducer at close
range in order to be subjected to sound
levels that could cause TTS and would
likely exhibit avoidance behavior to the
area near the transducer rather than
swim through at such a close range.
Further, the restricted beam shape of the
majority of the geophysical survey
equipment proposed for use makes it
unlikely that an animal would be
exposed more than briefly during the
passage of the vessel.
Behavioral Effects—Behavioral
disturbance may include a variety of
effects, including subtle changes in
behavior (e.g., minor or brief avoidance
of an area or changes in vocalizations),
more conspicuous changes in similar
behavioral activities, and more
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sustained and/or potentially severe
reactions, such as displacement from or
abandonment of high-quality habitat.
Behavioral responses to sound are
highly variable and context-specific and
any reactions depend on numerous
intrinsic and extrinsic factors (e.g.,
species, state of maturity, experience,
current activity, reproductive state,
auditory sensitivity, time of day), as
well as the interplay between factors
(e.g., Richardson et al., 1995; Wartzok et
al., 2003; Southall et al., 2007; Weilgart,
2007; Archer et al., 2010). Behavioral
reactions can vary not only among
individuals but also within an
individual, depending on previous
experience with a sound source,
context, and numerous other factors
(Ellison et al., 2012), and can vary
depending on characteristics associated
with the sound source (e.g., whether it
is moving or stationary, number of
sources, distance from the source).
Please see Appendices B–C of Southall
et al. (2007) for a review of studies
involving marine mammal behavioral
responses to sound.
Habituation can occur when an
animal’s response to a stimulus wanes
with repeated exposure, usually in the
absence of unpleasant associated events
(Wartzok et al., 2003). Animals are most
likely to habituate to sounds that are
predictable and unvarying. It is
important to note that habituation is
appropriately considered as a
‘‘progressive reduction in response to
stimuli that are perceived as neither
aversive nor beneficial,’’ rather than as,
more generally, moderation in response
to human disturbance (Bejder et al.,
2009). The opposite process is
sensitization, when an unpleasant
experience leads to subsequent
responses, often in the form of
avoidance, at a lower level of exposure.
As noted, behavioral state may affect the
type of response. For example, animals
that are resting may show greater
behavioral change in response to
disturbing sound levels than animals
that are highly motivated to remain in
an area for feeding (Richardson et al.,
1995; NRC, 2003; Wartzok et al., 2003).
Controlled experiments with captive
marine mammals have showed
pronounced behavioral reactions,
including avoidance of loud sound
sources (Ridgway et al., 1997; Finneran
et al., 2003). Observed responses of wild
marine mammals to loud pulsed sound
sources (typically airguns or acoustic
harassment devices) have been varied
but often consist of avoidance behavior
or other behavioral changes suggesting
discomfort (Morton and Symonds, 2002;
see also Richardson et al., 1995;
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Nowacek et al., 2007). However, many
delphinids approach low-frequency
airgun source vessels with no apparent
discomfort or obvious behavioral change
(e.g., Barkaszi et al., 2012), indicating
the importance of frequency output in
relation to the species’ hearing
sensitivity.
Available studies show wide variation
in response to underwater sound;
therefore, it is difficult to predict
specifically how any given sound in a
particular instance might affect marine
mammals perceiving the signal. If a
marine mammal does react briefly to an
underwater sound by changing its
behavior or moving a small distance, the
impacts of the change are unlikely to be
significant to the individual, let alone
the stock or population. However, if a
sound source displaces marine
mammals from an important feeding or
breeding area for a prolonged period,
impacts on individuals and populations
could be significant (e.g., Lusseau and
Bejder, 2007; Weilgart, 2007; NRC,
2005). However, there are broad
categories of potential response, which
we describe in greater detail here, that
include alteration of dive behavior,
alteration of foraging behavior, effects to
breathing, interference with or alteration
of vocalization, avoidance, and flight.
Changes in dive behavior can vary
widely and may consist of increased or
decreased dive times and surface
intervals as well as changes in the rates
of ascent and descent during a dive (e.g.,
Frankel and Clark, 2000; Costa et al.,
2003; Ng and Leung, 2003; Nowacek et
al.; 2004; Goldbogen et al., 2013a,
2013b). Variations in dive behavior may
reflect interruptions in biologically
significant activities (e.g., foraging) or
they may be of little biological
significance. The impact of an alteration
to dive behavior resulting from an
acoustic exposure depends on what the
animal is doing at the time of the
exposure and the type and magnitude of
the response.
Disruption of feeding behavior can be
difficult to correlate with anthropogenic
sound exposure, so it is usually inferred
by observed displacement from known
foraging areas, the appearance of
secondary indicators (e.g., bubble nets
or sediment plumes), or changes in dive
behavior. As for other types of
behavioral response, the frequency,
duration, and temporal pattern of signal
presentation, as well as differences in
species sensitivity, are likely
contributing factors to differences in
response in any given circumstance
(e.g., Croll et al., 2001; Nowacek et al.;
2004; Madsen et al., 2006; Yazvenko et
al., 2007). A determination of whether
foraging disruptions incur fitness
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consequences would require
information on or estimates of the
energetic requirements of the affected
individuals and the relationship
between prey availability, foraging effort
and success, and the life history stage of
the animal.
Variations in respiration naturally
vary with different behaviors and
alterations to breathing rate as a
function of acoustic exposure can be
expected to co-occur with other
behavioral reactions, such as a flight
response or an alteration in diving.
However, respiration rates in and of
themselves may be representative of
annoyance or an acute stress response.
Various studies have shown that
respiration rates may either be
unaffected or could increase, depending
on the species and signal characteristics,
again highlighting the importance in
understanding species differences in the
tolerance of underwater noise when
determining the potential for impacts
resulting from anthropogenic sound
exposure (e.g., Kastelein et al., 2001,
2005, 2006; Gailey et al., 2007; Gailey et
al., 2016).
Marine mammals vocalize for
different purposes and across multiple
modes, such as whistling, echolocation
click production, calling, and singing.
Changes in vocalization behavior in
response to anthropogenic noise can
occur for any of these modes and may
result from a need to compete with an
increase in background noise or may
reflect increased vigilance or a startle
response. For example, in the presence
of potentially masking signals,
humpback whales and killer whales
have been observed to increase the
length of their songs (Miller et al., 2000;
Fristrup et al., 2003; Foote et al., 2004),
while right whales have been observed
to shift the frequency content of their
calls upward while reducing the rate of
calling in areas of increased
anthropogenic noise (Parks et al., 2007).
In some cases, animals may cease sound
production during production of
aversive signals (Bowles et al., 1994).
Avoidance is the displacement of an
individual from an area or migration
path as a result of the presence of a
sound or other stressors, and is one of
the most obvious manifestations of
disturbance in marine mammals
(Richardson et al., 1995). For example,
gray whales are known to change
direction—deflecting from customary
migratory paths—in order to avoid noise
from airgun surveys (Malme et al.,
1984). Avoidance may be short-term,
with animals returning to the area once
the noise has ceased (e.g., Bowles et al.,
1994; Goold, 1996; Stone et al., 2000;
Morton and Symonds, 2002; Gailey et
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al., 2007). Longer-term displacement is
possible, however, which may lead to
changes in abundance or distribution
patterns of the affected species in the
affected region if habituation to the
presence of the sound does not occur
(e.g., Blackwell et al., 2004; Bejder et al.,
2006; Teilmann et al., 2006).
A flight response is a dramatic change
in normal movement to a directed and
rapid movement away from the
perceived location of a sound source.
The flight response differs from other
avoidance responses in the intensity of
the response (e.g., directed movement,
rate of travel). Relatively little
information on flight responses of
marine mammals to anthropogenic
signals exist, although observations of
flight responses to the presence of
predators have occurred (Connor and
Heithaus, 1996). The result of a flight
response could range from brief,
temporary exertion and displacement
from the area where the signal provokes
flight to, in extreme cases, marine
mammal strandings (Evans and
England, 2001). However, it should be
noted that response to a perceived
predator does not necessarily invoke
flight (Ford and Reeves, 2008), and
whether individuals are solitary or in
groups may influence the response.
Behavioral disturbance can also
impact marine mammals in more subtle
ways. Increased vigilance may result in
costs related to diversion of focus and
attention (i.e., when a response consists
of increased vigilance, it may come at
the cost of decreased attention to other
critical behaviors such as foraging or
resting). These effects have generally not
been demonstrated for marine
mammals, but studies involving fish
and terrestrial animals have shown that
increased vigilance may substantially
reduce feeding rates (e.g., Beauchamp
and Livoreil, 1997; Fritz et al., 2002;
Purser and Radford, 2011). In addition,
chronic disturbance can cause
population declines through reduction
of fitness (e.g., decline in body
condition) and subsequent reduction in
reproductive success, survival, or both
(e.g., Harrington and Veitch, 1992; Daan
et al., 1996; Bradshaw et al., 1998).
However, Ridgway et al. (2006) reported
that increased vigilance in bottlenose
dolphins exposed to sound over a fiveday period did not cause any sleep
deprivation or stress effects.
Many animals perform vital functions,
such as feeding, resting, traveling, and
socializing, on a diel cycle (24-hour
cycle). Disruption of such functions
resulting from reactions to stressors
such as sound exposure are more likely
to be significant if they last more than
one diel cycle or recur on subsequent
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days (Southall et al., 2007).
Consequently, a behavioral response
lasting less than one day and not
recurring on subsequent days is not
considered particularly severe unless it
could directly affect reproduction or
survival (Southall et al., 2007). Note that
there is a difference between multi-day
substantive behavioral reactions and
multi-day anthropogenic activities. For
example, just because an activity lasts
for multiple days does not necessarily
mean that individual animals are either
exposed to activity-related stressors for
multiple days or, further, exposed in a
manner resulting in sustained multi-day
substantive behavioral responses.
We expect that some marine
mammals may exhibit behavioral
responses to the HRG survey activities
in the form of avoidance of the area
during the activity, especially the
naturally shy harbor porpoise, while
others such as delphinids might be
attracted to the survey activities out of
curiosity. However, because the HRG
survey equipment operates from a
moving vessel, and the maximum radius
to the Level B harassment threshold is
relatively small, the area and time that
this equipment would be affecting a
given location is very small. Further,
once an area has been surveyed, it is not
likely that it will be surveyed again,
thereby reducing the likelihood of
repeated impacts within the Project
Area.
We have also considered the potential
for severe behavioral responses such as
stranding and associated indirect injury
or mortality from Mayflower’s use of
HRG survey equipment. Commenters on
previous IHAs involving HRG surveys
have referenced a 2008 mass stranding
of approximately 100 melon-headed
whales in a Madagascar lagoon system.
An investigation of the event indicated
that use of a high-frequency mapping
system (12-kHz multibeam
echosounder) was the most plausible
and likely initial behavioral trigger of
the event, while providing the caveat
that there is no unequivocal and easily
identifiable single cause (Southall et al.,
2013). The investigatory panel’s
conclusion was based on (1) very close
temporal and spatial association and
directed movement of the survey with
the stranding event; (2) the unusual
nature of such an event coupled with
previously documented apparent
behavioral sensitivity of the species to
other sound types (Southall et al., 2006;
Brownell et al., 2009); and (3) the fact
that all other possible factors considered
were determined to be unlikely causes.
Specifically, regarding survey patterns
prior to the event and in relation to
bathymetry, the vessel transited in a
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north-south direction on the shelf break
parallel to the shore, ensonifying large
areas of deep-water habitat prior to
operating intermittently in a
concentrated area offshore from the
stranding site; this may have trapped
the animals between the sound source
and the shore, thus driving them
towards the lagoon system. The
investigatory panel systematically
excluded or deemed highly unlikely
nearly all potential reasons for these
animals leaving their typical pelagic
habitat for an area extremely atypical for
the species (i.e., a shallow lagoon
system). Notably, this was the first time
that such a system has been associated
with a stranding event. The panel also
noted several site- and situation-specific
secondary factors that may have
contributed to the avoidance responses
that led to the eventual entrapment and
mortality of the whales. Specifically,
shoreward-directed surface currents and
elevated chlorophyll levels in the area
preceding the event may have played a
role (Southall et al., 2013). The report
also notes that prior use of a similar
system in the general area may have
sensitized the animals and also
concluded that, for odontocete
cetaceans that hear well in higher
frequency ranges where ambient noise is
typically quite low, high-power active
sonars operating in this range may be
more easily audible and have potential
effects over larger areas than low
frequency systems that have more
typically been considered in terms of
anthropogenic noise impacts. It is,
however, important to note that the
relatively lower output frequency,
higher output power, and complex
nature of the system implicated in this
event, in context of the other factors
noted here, likely produced a fairly
unusual set of circumstances that
indicate that such events would likely
remain rare and are not necessarily
relevant to use of lower-power, higherfrequency systems more commonly used
for HRG survey applications. The risk of
similar events recurring is likely very
low, given the extensive use of active
acoustic systems used for scientific and
navigational purposes worldwide on a
daily basis and the lack of direct
evidence of such responses previously
reported.
Stress Responses—An animal’s
perception of a threat may be sufficient
to trigger stress responses consisting of
some combination of behavioral
responses, autonomic nervous system
responses, neuroendocrine responses, or
immune responses (e.g., Seyle, 1950;
Moberg, 2000). In many cases, an
animal’s first and sometimes most
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economical (in terms of energetic costs)
response is behavioral avoidance of the
potential stressor. Autonomic nervous
system responses to stress typically
involve changes in heart rate, blood
pressure, and gastrointestinal activity.
These responses have a relatively short
duration and may or may not have a
significant long-term effect on an
animal’s fitness.
Neuroendocrine stress responses often
involve the hypothalamus-pituitaryadrenal system. Virtually all
neuroendocrine functions that are
affected by stress—including immune
competence, reproduction, metabolism,
and behavior—are regulated by pituitary
hormones. Stress-induced changes in
the secretion of pituitary hormones have
been implicated in failed reproduction,
altered metabolism, reduced immune
competence, and behavioral disturbance
(e.g., Moberg, 1987; Blecha, 2000).
Increases in the circulation of
glucocorticoids are also equated with
stress (Romano et al., 2004).
The primary distinction between
stress (which is adaptive and does not
normally place an animal at risk) and
‘‘distress’’ is the cost of the response.
During a stress response, an animal uses
glycogen stores that can be quickly
replenished once the stress is alleviated.
In such circumstances, the cost of the
stress response would not pose serious
fitness consequences. However, when
an animal does not have sufficient
energy reserves to satisfy the energetic
costs of a stress response, energy
resources must be diverted from other
functions. This state of distress will last
until the animal replenishes its
energetic reserves sufficient to restore
normal function.
Relationships between these
physiological mechanisms, animal
behavior, and the costs of stress
responses are well studied through
controlled experiments and for both
laboratory and free-ranging animals
(e.g., Holberton et al., 1996; Hood et al.,
1998; Jessop et al., 2003; Krausman et
al., 2004; Lankford et al., 2005). Stress
responses due to exposure to
anthropogenic sounds or other stressors
and their effects on marine mammals
have also been reviewed (Fair and
Becker, 2000; Romano et al., 2002b)
and, more rarely, studied in wild
populations (e.g., Romano et al., 2002a).
For example, Rolland et al. (2012) found
that noise reduction from reduced ship
traffic in the Bay of Fundy was
associated with decreased stress in
North Atlantic right whales. These and
other studies lead to a reasonable
expectation that some marine mammals
will experience physiological stress
responses upon exposure to acoustic
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stressors and that it is possible that
some of these would be classified as
‘‘distress.’’ In addition, any animal
experiencing TTS would likely also
experience stress responses (NRC,
2003).
NMFS does not expect that the
generally short-term, intermittent, and
transitory HRG activities would create
conditions of long-term, continuous
noise and chronic acoustic exposure
leading to long-term physiological stress
responses in marine mammals.
Auditory Masking—Sound can
disrupt behavior through masking, or
interfering with, an animal’s ability to
detect, recognize, or discriminate
between acoustic signals of interest (e.g.,
those used for intraspecific
communication and social interactions,
prey detection, predator avoidance,
navigation) (Richardson et al., 1995;
Erbe et al., 2016). Masking occurs when
the receipt of a sound is interfered with
by another coincident sound at similar
frequencies and at similar or higher
intensity, and may occur whether the
sound is natural (e.g., snapping shrimp,
wind, waves, precipitation) or
anthropogenic (e.g., shipping, sonar,
seismic exploration) in origin. The
ability of a noise source to mask
biologically important sounds depends
on the characteristics of both the noise
source and the signal of interest (e.g.,
signal-to-noise ratio, temporal
variability, direction), in relation to each
other and to an animal’s hearing
abilities (e.g., sensitivity, frequency
range, critical ratios, frequency
discrimination, directional
discrimination, age or TTS hearing loss),
and existing ambient noise and
propagation conditions.
Under certain circumstances, marine
mammals experiencing significant
masking could also be impaired from
maximizing their performance fitness in
survival and reproduction. Therefore,
when the coincident (masking) sound is
man-made, it may be considered
harassment if disrupting behavioral
patterns. It is important to distinguish
TTS and PTS, which persist after the
sound exposure, from masking, which
occurs during the sound exposure.
Because masking (without resulting in
TS) is not associated with abnormal
physiological function, it is not
considered a physiological effect, but
rather a potential behavioral effect.
The frequency range of the potentially
masking sound is important in
determining any potential behavioral
impacts. For example, low-frequency
signals may have less effect on highfrequency echolocation sounds
produced by odontocetes but are more
likely to affect detection of mysticete
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communication calls and other
potentially important natural sounds
such as those produced by surf and
some prey species. The masking of
communication signals by
anthropogenic noise may be considered
as a reduction in the communication
space of animals (e.g., Clark et al., 2009)
and may result in energetic or other
costs as animals change their
vocalization behavior (e.g., Miller et al.,
2000; Foote et al., 2004; Parks et al.,
2007; Di Iorio and Clark, 2009; Holt et
al., 2009). Masking can be reduced in
situations where the signal and noise
come from different directions
(Richardson et al., 1995), through
amplitude modulation of the signal, or
through other compensatory behaviors
(Houser and Moore, 2014). Masking can
be tested directly in captive species
(e.g., Erbe, 2008), but in wild
populations it must be either modeled
or inferred from evidence of masking
compensation. There are few studies
addressing real-world masking sounds
likely to be experienced by marine
mammals in the wild (e.g., Branstetter et
al., 2013).
Masking affects both senders and
receivers of acoustic signals and can
potentially have long-term chronic
effects on marine mammals at the
population level as well as at the
individual level. Low-frequency
ambient sound levels have increased by
as much as 20 dB (more than three times
in terms of SPL) in the world’s ocean
from pre-industrial periods, with most
of the increase from distant commercial
shipping (Hildebrand, 2009). All
anthropogenic sound sources, but
especially chronic and lower-frequency
signals (e.g., from vessel traffic),
contribute to elevated ambient sound
levels, thus intensifying masking.
Marine mammal communications
would not likely be masked appreciably
by the HRG equipment given the
directionality of the signals (for most
geophysical survey equipment types
proposed for use (Table 1) and the brief
period when an individual mammal is
likely to be within its beam.
Vessel Strike
Vessel strikes of marine mammals can
cause significant wounds, which may
lead to the death of the animal. An
animal at the surface could be struck
directly by a vessel, a surfacing animal
could hit the bottom of a vessel, or a
vessel’s propeller could injure an
animal just below the surface. The
severity of injuries typically depends on
the size and speed of the vessel
(Knowlton and Kraus 2001; Laist et al.,
2001; Vanderlaan and Taggart 2007).
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The most vulnerable marine mammals
are those that spend extended periods of
time at the surface in order to restore
oxygen levels within their tissues after
deep dives (e.g., the sperm whale). In
addition, some baleen whales, such as
the North Atlantic right whale, seem
generally unresponsive to vessel sound,
making them more susceptible to vessel
collisions (Nowacek et al., 2004). These
species are primarily large, slow moving
whales. Smaller marine mammals (e.g.,
bottlenose dolphin) move quickly
through the water column and are often
seen riding the bow wave of large ships.
Marine mammal responses to vessels
may include avoidance and changes in
dive pattern (NRC 2003). An
examination of all known ship strikes
from all shipping sources (civilian and
military) indicates vessel speed is a
principal factor in whether a vessel
strike results in death (Knowlton and
Kraus 2001; Laist et al., 2001; Jensen
and Silber 2003; Vanderlaan and
Taggart 2007). In assessing records with
known vessel speeds, Laist et al. (2001)
found a direct relationship between the
occurrence of a whale strike and the
speed of the vessel involved in the
collision. The authors concluded that
most deaths occurred when a vessel was
traveling in excess of 24.1 km/h (14.9
mph; 13 kn). Given the slow vessel
speeds and predictable course necessary
for data acquisition, ship strike is
unlikely to occur during the geophysical
surveys. Marine mammals would be
able to easily avoid the survey vessel
due to the slow vessel speed. Further,
Mayflower would implement measures
(e.g., protected species monitoring,
vessel speed restrictions and separation
distances; see Proposed Mitigation) set
forth in the BOEM lease to reduce the
risk of a vessel strike to marine mammal
species in the Project Area.
Anticipated Effects on Marine Mammal
Habitat
The proposed activities would not
result in permanent impacts to habitats
used directly by marine mammals, but
may have potential minor and shortterm impacts to food sources such as
forage fish. The proposed activities
could affect acoustic habitat (see
masking discussion above), but
meaningful impacts are unlikely. There
are no feeding areas, rookeries, or
mating grounds known to be
biologically important to marine
mammals within the proposed Project
Area with the exception of feeding BIAs
for right, humpback, fin, and sei whales
and a migratory BIA for right whales
which were described previously. The
HRG survey equipment will not contact
the substrate and does not represent a
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source of pollution. Impacts to substrate
or from pollution are therefore not
discussed further.
Effects to Prey—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.
Fish utilize the soundscape 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 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
noise 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
impulse 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). However, some studies have
shown no or slight reaction to impulse
sounds (e.g., Pena et al., 2013; Wardle
et al., 2001; Jorgenson and Gyselman,
2009; Cott et al., 2012). More
commonly, though, the impacts of noise
on fish are temporary.
We are not aware of any available
literature on impacts to marine mammal
prey from sound produced by HRG
survey equipment. However, as the HRG
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survey equipment introduces noise to
the marine environment, there is the
potential for it to result in avoidance of
the area around the HRG survey
activities on the part of marine mammal
prey. The duration of fish avoidance of
an area after HRG surveys depart the
area is unknown, but a rapid return to
normal recruitment, distribution and
behavior is anticipated. In general,
impacts to marine mammal prey species
are expected to be minor and temporary
due to the expected short daily duration
of the proposed HRG survey, the fact
that the proposed survey is mobile
rather than stationary, and the relatively
small areas potentially affected. The
areas likely impacted by the proposed
activities are relatively small compared
to the available habitat in the Atlantic
Ocean. Any behavioral avoidance by
fish of the disturbed area would still
leave significantly large areas of fish and
marine mammal foraging habitat in the
nearby vicinity. Based on the
information discussed herein, we
conclude that impacts of the specified
activity are not likely to have more than
short-term adverse effects on any prey
habitat or populations of prey species.
Because of the temporary nature of the
disturbance, and the availability of
similar habitat and resources (e.g., prey
species) in the surrounding area, 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.
Effects to habitat will not be discussed
further in this document.
Estimated Take
This section provides an estimate of
the number of incidental takes proposed
for authorization through this IHA,
which will inform both NMFS’
consideration of ‘‘small numbers’’ and
the negligible impact determination.
Harassment is the only type of take
expected to result from these activities.
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).
Authorized takes would be by Level B
harassment only in the form of
disruption of behavioral patterns for
individual marine mammals resulting
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from exposure to HRG sources. Based on
the nature of the activity and the
anticipated effectiveness of the
mitigation measures (i.e., exclusion
zones and shutdown measures),
discussed in detail below in Proposed
Mitigation section, Level A harassment
is neither anticipated nor proposed to be
authorized.
As described previously, no mortality
is anticipated or proposed to be
authorized for this activity. Below we
describe how the take is estimated.
Generally speaking, we estimate take
by considering: (1) Acoustic thresholds
above which NMFS believes the best
available science indicates marine
mammals will be behaviorally harassed
or incur some degree of permanent
hearing impairment; (2) the area or
volume of water that will be ensonified
above these levels in a day; (3) the
density or occurrence of marine
mammals within these ensonified areas;
and, (4) and the number of days of
activities. We note that while these
basic factors can contribute to a basic
calculation to provide an initial
prediction of takes, additional
information that can qualitatively
inform take estimates is also sometimes
available (e.g., previous monitoring
results or average group size). Below, we
describe the factors considered here in
more detail and present the proposed
take estimate.
Acoustic Thresholds
Using the best available science,
NMFS has developed acoustic
thresholds that identify the received
level of underwater sound above which
exposed marine mammals would be
reasonably expected to be behaviorally
harassed (equated to Level B
harassment) or to incur PTS of some
degree (equated to Level A harassment).
Level B Harassment for non-explosive
sources—Though significantly driven by
received level, the onset of behavioral
disturbance from anthropogenic noise
exposure is also informed to varying
degrees by other factors related to the
source (e.g., frequency, predictability,
duty cycle), the environment (e.g.,
bathymetry), and the receiving animals
(hearing, motivation, experience,
demography, behavioral context) and
can be difficult to predict (Southall et
al., 2007, Ellison et al., 2012). Based on
what the available science indicates and
the practical need to use a threshold
based on a factor that is both predictable
and measurable for most activities,
NMFS uses a generalized acoustic
threshold based on received level to
estimate the onset of behavioral
harassment. NMFS predicts that marine
mammals are likely to be behaviorally
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harassed in a manner we consider Level
B harassment when exposed to
underwater anthropogenic noise above
received levels of 160 dB re 1 mPa (rms)
for impulsive and/or intermittent
sources (e.g., impact pile driving) and
120 dB rms for continuous sources (e.g.,
vibratory driving). Mayflower’s
proposed activity includes the use of
impulsive sources (geophysical survey
equipment), and therefore use of the 160
dB re 1 mPa (rms) threshold is
applicable.
Level A harassment for non-explosive
sources—NMFS’ Technical Guidance
for Assessing the Effects of
Anthropogenic Sound on Marine
Mammal Hearing (Version 2.0)
(Technical Guidance, 2018) identifies
dual criteria to assess auditory injury
(Level A harassment) to five different
marine mammal groups (based on
hearing sensitivity) as a result of
exposure to noise from two different
types of sources (impulsive or nonimpulsive). The components of
Mayflower’s proposed activity includes
the use of impulsive sources.
Predicted distances to Level A
harassment isopleths, which vary based
on marine mammal functional hearing
groups were calculated. The updated
acoustic thresholds for impulsive
sounds (such as HRG survey equipment)
contained in the Technical Guidance
(NMFS, 2018) were presented as dual
metric acoustic thresholds using both
SELcum and peak sound pressure level
metrics. As dual metrics, NMFS
considers onset of PTS (Level A
harassment) to have occurred when
either one of the two metrics is
exceeded (i.e., metric resulting in the
largest isopleth). The SELcum metric
considers both level and duration of
exposure, as well as auditory weighting
functions by marine mammal hearing
group.
These thresholds are provided in
Table 5 below. The references, analysis,
and methodology used in the
development of the thresholds are
described in NMFS 2018 Technical
Guidance, which may be accessed at:
www.fisheries.noaa.gov/national/
marine-mammal-protection/marinemammal-acoustic-technical-guidance.
TABLE 5—THRESHOLDS IDENTIFYING THE ONSET OF PERMANENT THRESHOLD SHIFT
PTS onset acoustic thresholds *
(Received Level)
Hearing group
Impulsive
Low-Frequency (LF) Cetaceans ......................................
Mid-Frequency (MF) Cetaceans ......................................
High-Frequency (HF) Cetaceans .....................................
Phocid Pinnipeds (PW) (Underwater) .............................
Otariid Pinnipeds (OW) (Underwater) .............................
NMFS considers the data provided by
Crocker and Fratantonio (2016) to
represent the best available information
on source levels associated with HRG
equipment and therefore recommends
that source levels provided by Crocker
and Fratantonio (2016) be incorporated
in the method described above to
estimate isopleth distances to the Level
B harassment threshold. In cases when
the source level for a specific type of
HRG equipment is not provided in
Crocker and Fratantonio (2016), NMFS
recommends that either the source
levels provided by the manufacturer be
used, or, in instances where source
levels provided by the manufacturer are
unavailable or unreliable, a proxy from
Crocker and Fratantonio (2016) be used
instead. Table 2 shows the HRG
equipment types that may be used
during the proposed surveys and the
Cell
Cell
Cell
Cell
Cell
1:
3:
5:
7:
9:
Non-impulsive
L pk,flat: 219 dB; L E,LF,24h: 183 dB ......................
Lpk,flat: 230 dB; LE,MF,24h: 185 dB ........................
Lpk,flat: 202 dB; LE,HF,24h: 155 dB ........................
Lpk,flat: 218 dB LE,PW,24h: 185 dB ........................
Lpk,flat: 232 dB; LE,OW,24h: 203 dB .......................
sound levels associated with those HRG
equipment types. Tables 2 and 4 of
Appendix B in the IHA application
shows the literature sources for the
sound source levels that are shown in
Table 2 and that were incorporated into
the modeling of Level B isopleth
distances to the Level B harassment
threshold.
Results of modeling using the
methodology described above indicated
that, of the HRG survey equipment
planned for use by Mayflower that has
the potential to result in harassment of
marine mammals, sound produced by
the Geomarine Geo-Spark 400 tip
sparker would propagate furthest to the
Level B harassment threshold (Table 6);
therefore, for the purposes of the
exposure analysis, it was assumed the
Geomarine Geo-Spark 400 tip sparker
would be active during the entire
duration of the surveys. Thus the
Cell
Cell
Cell
Cell
Cell
2: LE,LF,24h: 199 dB.
4: LE,MF,24h: 198 dB.
6: LE,HF,24h: 173 dB.
8: LE,PW,24h: 201 dB.
10: LE,OW,24h: 219 dB.
distance to the isopleth corresponding
to the threshold for Level B harassment
for the Geomarine Geo-Spark 400 tip
sparker (estimated at 141 m; Table 6)
was used as the basis of the take
calculation for all marine mammals.
Note that this results in a conservative
estimate of the total ensonified area
resulting from the proposed activities as
Mayflower may not operate the
Geomarine Geo-Spark 400 tip sparker
during the entire proposed survey, and
for any survey segments in which it is
not ultimately operated, the distance to
the Level B harassment threshold would
be less than 141 m (Table 6). However,
as Mayflower cannot predict the precise
number of survey days that will require
the use of the Geomarine Geo-Spark 400
tip sparker, it was assumed that it
would be operated during the entire
duration of the proposed surveys.
TABLE 6—MODELED RADIAL DISTANCES FROM HRG SURVEY EQUIPMENT TO ISOPLETHS CORRESPONDING TO LEVEL A
AND LEVEL B HARASSMENT THRESHOLDS
jbell on DSKJLSW7X2PROD with NOTICES2
Radial distance to level A harassment threshold (m) *
Sound source
Low frequency
cetaceans
Mid frequency
cetaceans
High frequency
cetaceans
Phocid pinnipeds
(underwater)
Radial distance
to level B
harassment
threshold
(m)
All marine
mammals
Innomar SES–2000 Medium-100 Parametric ..........
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TABLE 6—MODELED RADIAL DISTANCES FROM HRG SURVEY EQUIPMENT TO ISOPLETHS CORRESPONDING TO LEVEL A
AND LEVEL B HARASSMENT THRESHOLDS—Continued
Radial distance to level A harassment threshold (m) *
Sound source
Low frequency
cetaceans
Mid frequency
cetaceans
High frequency
cetaceans
Phocid pinnipeds
(underwater)
Radial distance
to level B
harassment
threshold
(m)
All marine
mammals
Edgetech 2000–DSS ...............................................
Geomarine Geo-Spark 400 tip sparker (800
Joules) ..................................................................
<1
<1
3
<1
5
<1
<1
8
<1
141
jbell on DSKJLSW7X2PROD with NOTICES2
* Distances to the Level A harassment threshold based on the larger of the dual criteria (peak SPL and SELcum) are shown. For all sources the
SELcum metric resulted in larger isopleth distances.
Predicted distances to Level A
harassment isopleths, which vary based
on marine mammal functional hearing
groups (Table 5), were also calculated.
The updated acoustic thresholds for
impulsive sounds (such as HRG survey
equipment) contained in the Technical
Guidance (NMFS, 2018) were presented
as dual metric acoustic thresholds using
both cumulative sound exposure level
(SELcum) and peak sound pressure level
metrics. As dual metrics, NMFS
considers onset of PTS (Level A
harassment) to have occurred when
either one of the two metrics is
exceeded (i.e., the metric resulting in
the largest isopleth). The SELcum metric
considers both level and duration of
exposure, as well as auditory weighting
functions by marine mammal hearing
group.
Modeling of distances to isopleths
corresponding to the Level A
harassment threshold was performed for
all types of HRG equipment proposed
for use with the potential to result in
harassment of marine mammals.
Mayflower used a new model developed
by JASCO to calculate distances to Level
A harassment isopleths based on both
the peak SPL and the SELcum metric. For
the peak SPL metric, the model is a
series of equations that accounts for
both seawater absorption and HRG
equipment beam patterns (for all HRG
sources with beam widths larger than
90°, it was assumed these sources were
omnidirectional). For the SELcum metric,
a model was developed that accounts
for the hearing sensitivity of the marine
mammal group, seawater absorption,
and beam width for downwards-facing
transducers. Details of the modeling
methodology for both the peak SPL and
SELcum metrics are provided in
Appendix A of the IHA application.
This model entails the following steps:
1. Weighted broadband source levels
were calculated by assuming a flat
spectrum between the source minimum
and maximum frequency, weighted the
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spectrum according to the marine
mammal hearing group weighting
function (NMFS 2018), and summed
across frequency;
2. Propagation loss was modeled as a
function of oblique range;
3. Per-pulse SEL was modeled for a
stationary receiver at a fixed distance off
a straight survey line, using a vessel
transit speed of 3.5 knots and sourcespecific pulse length and repetition rate.
The off-line distance is referred to as the
closest point of approach (CPA) and was
performed for CPA distances between 1
m and 10 km. The survey line length
was modeled as 10 km long (analysis
showed longer survey lines increased
SEL by a negligible amount). SEL is
calculated as SPL + 10 log10 T/15 dB,
where T is the pulse duration;
4. The SEL for each survey line was
calculated to produce curves of
weighted SEL as a function of CPA
distance; and
5. The curves from Step 4 above were
used to estimate the CPA distance to the
impact criteria.
We note that in the modeling methods
described above and in Appendix A of
the IHA application, sources that
operate with a repetition rate greater
than 10 Hz were assessed with the nonimpulsive (intermittent) source criteria
while sources with a repetition rate
equal to or less than 10 Hz were
assessed with the impulsive source
criteria. NMFS does not necessarily
agree with this step in the modeling
assessment, which results in nearly all
HRG sources being classified as
impulsive; however, we note that the
classification of the majority of HRG
sources as impulsive results in more
conservative modeling results. Thus, we
have assessed the potential for Level A
harassment to result from the proposed
activities based on the modeled Level A
zones with the acknowledgement that
these zones are likely conservative.
Modeled isopleth distances to Level A
harassment thresholds for all types of
PO 00000
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HRG equipment and all marine mammal
functional hearing groups are shown in
Table 6. The dual criteria (peak SPL and
SELcum) were applied to all HRG sources
using the modeling methodology as
described above, and the largest isopleth
distances for each functional hearing
group were then carried forward in the
exposure analysis to be conservative.
For all HRG sources, the SELcum metric
resulted in larger isopleth distances.
Distances to the Level A harassment
threshold based on the larger of the dual
criteria (peak SPL and SELcum) are
shown in Table 6.
Modeled distances to isopleths
corresponding to the Level A
harassment threshold are very small (<1
m) for three of the four marine mammal
functional hearing groups that may be
impacted by the proposed activities (i.e.,
low frequency and mid frequency
cetaceans, and phocid pinnipeds; see
Table 6). Based on the very small Level
A harassment zones for these functional
hearing groups, the potential for species
within these functional hearing groups
to be taken by Level A harassment is
considered so low as to be discountable.
For harbor porpoises (a high frequency
specialist), the largest modeled distance
to the Level A harassment threshold for
the high frequency functional hearing
group was 60 m (Table 6). However, as
noted above, modeled distances to
isopleths corresponding to the Level A
harassment threshold are assumed to be
conservative. Further, the Innomar
source uses a very narrow beam width
(two degrees) and the distances to the
Level A harassment isopleths are eight
meters or less for the other two sources.
Level A harassment would also be more
likely to occur at close approach to the
sound source or as a result of longer
duration exposure to the sound source,
and mitigation measures—including a
100-m exclusion zone for harbor
porpoises—are expected to minimize
the potential for close approach or
longer duration exposure to active HRG
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sources. In addition, harbor porpoises
are a notoriously shy species which is
known to avoid vessels, and would also
be expected to avoid a sound source
prior to that source reaching a level that
would result in injury (Level A
harassment). Therefore, we have
determined that the potential for take by
Level A harassment of harbor porpoises
is so low as to be discountable. As
NMFS has determined that the
likelihood of take of any marine
mammals in the form of Level A
harassment occurring as a result of the
proposed surveys is so low as to be
discountable, we therefore do not
propose to authorize the take by Level
A harassment of any marine mammals.
Marine Mammal Occurrence
In this section we provide the
information about the presence, density,
or group dynamics of marine mammals
that will inform the take calculations.
The habitat-based density models
produced by the Duke University
Marine Geospatial Ecology Laboratory
(Roberts et al., 2016, 2017, 2018)
represent the best available information
regarding marine mammal densities in
the proposed survey area. The density
data presented by Roberts et al. (2016,
2017, 2018) incorporates aerial and
shipboard line-transect survey data from
NMFS and other organizations and
incorporates data from 8 physiographic
and 16 dynamic oceanographic and
biological covariates, and controls for
the influence of sea state, group size,
availability bias, and perception bias on
the probability of making a sighting.
These density models were originally
developed for all cetacean taxa in the
U.S. Atlantic (Roberts et al., 2016). In
subsequent years, certain models have
been updated on the basis of additional
data as well as certain methodological
improvements. Our evaluation of the
changes leads to a conclusion that these
represent the best scientific evidence
available. More information, including
the model results and supplementary
information for each model, is available
online at seamap.env.duke.edu/models/
Duke-EC-GOM-2015/. Marine mammal
density estimates in the project area
(animals/km2) were obtained using
these model results (Roberts et al., 2016,
2017, 2018). The updated models
incorporate additional sighting data,
including sightings from the NOAA
Atlantic Marine Assessment Program for
Protected Species (AMAPPS) surveys
from 2010–2014 (NEFSC & SEFSC,
2011, 2012, 2014a, 2014b, 2015, 2016).
For the exposure analysis, density
data from Roberts et al. (2016, 2017,
2018) were mapped using a geographic
information system (GIS). These data
provide abundance estimates for species
or species guilds within 10 km x 10 km
grid cells (100 km2) on a monthly or
annual basis, depending on the species.
In order to select a representative
sample of grid cells in and near the
Project Area, a 10-km wide perimeter
around the Lease Area and an 8-km
wide perimeter around the cable route
were created in GIS (ESRI 2017). The
perimeters were then used to select grid
cells near the Project Area containing
the most recent monthly or annual
estimates for each species in the Roberts
et al. (2016, 2017, 2018) data. The
average monthly abundance for each
species in each survey area (deep-water
and shallow-water) was calculated as
the mean value of the grid cells within
each survey portion in each month (June
through September), and then converted
for density (individuals/km2) by
dividing by 100 km2 (Tables 7 and 8).
Roberts et al. (2018) produced density
models for all seals and did not
differentiate by seal species. Because the
seasonality and habitat use by gray seals
roughly overlaps with that of harbor
seals in the survey areas, it was assumed
that modeled takes of seals could occur
to either of the respective species, thus
the total number of modeled takes for
seals was applied to each species.
TABLE 7—AVERAGE MONTHLY DENSITIES FOR SPECIES IN THE LEASE AREA AND DEEP-WATER SECTION OF THE CABLE
ROUTE
Estimated monthly density
(individuals/km2)
Species
June
Fin whale .........................................................................................................
Humpback whale .............................................................................................
Minke whale .....................................................................................................
North Atlantic right whale ................................................................................
Sei whale .........................................................................................................
Atlantic white-sided dolphin .............................................................................
Bottlenose dolphin ...........................................................................................
Harbor porpoise ...............................................................................................
Pilot whale .......................................................................................................
Risso’s dolphin .................................................................................................
Common dolphin ..............................................................................................
Sperm whale ....................................................................................................
Seals (harbor and gray) ...................................................................................
0.0032
0.0014
0.0024
0.0012
0.0002
0.0628
0.0249
0.0188
0.0066
0.0002
0.0556
0.0001
0.0260
July
August
0.0033
0.0011
0.0010
0.0000
0.0001
0.0446
0.0516
0.0125
0.0066
0.0005
0.0614
0.0004
0.0061
0.0029
0.0005
0.0007
0.0000
0.0000
0.0243
0.0396
0.0114
0.0066
0.0009
0.1069
0.0004
0.0033
September
0.0025
0.0011
0.0008
0.0000
0.0001
0.0246
0.0494
0.0093
0.0066
0.0007
0.1711
0.0002
0.0040
TABLE 8—AVERAGE MONTHLY DENSITIES FOR SPECIES IN THE SHALLOW-WATER SECTION OF THE CABLE ROUTE
Estimated monthly density
(individuals/km2)
Species
jbell on DSKJLSW7X2PROD with NOTICES2
June
Fin whale .........................................................................................................
Humpback whale .............................................................................................
Minke whale .....................................................................................................
North Atlantic right whale ................................................................................
Sei whale .........................................................................................................
Atlantic white-sided dolphin .............................................................................
Bottlenose dolphin ...........................................................................................
Harbor porpoise ...............................................................................................
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0.0003
0.0001
0.0002
0.0000
0.0000
0.0010
0.2308
0.0048
July
August
0.0003
0.0001
0.0000
0.0000
0.0000
0.0006
0.4199
0.0023
E:\FR\FM\27MYN2.SGM
27MYN2
0.0003
0.0000
0.0000
0.0000
0.0000
0.0005
0.3211
0.0037
September
0.0003
0.0001
0.0000
0.0000
0.0000
0.0008
0.3077
0.0036
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TABLE 8—AVERAGE MONTHLY DENSITIES FOR SPECIES IN THE SHALLOW-WATER SECTION OF THE CABLE ROUTE—
Continued
Estimated monthly density
(individuals/km2)
Species
June
Pilot whale .......................................................................................................
Risso’s dolphin .................................................................................................
Common dolphin ..............................................................................................
Sperm whale ....................................................................................................
Seals (harbor and gray) ...................................................................................
Take Calculation and Estimation
Here we describe how the information
provided above is brought together to
produce a quantitative take estimate.
In order to estimate the number of
marine mammals predicted to be
exposed to sound levels that would
result in harassment, radial distances to
predicted isopleths corresponding to
harassment thresholds are calculated, as
described above. Those distances are
then used to calculate the area(s) around
the HRG survey equipment predicted to
be ensonified to sound levels that
exceed harassment thresholds. The area
estimated to be ensonified to relevant
thresholds in a single day is then
calculated, based on areas predicted to
be ensonified around the HRG survey
equipment and the estimated trackline
distance traveled per day by the survey
vessel. Mayflower estimates that the
proposed survey vessel in the Lease
Area and deep-water sections of the
cable route will achieve a maximum
daily trackline of 110 km per day and
the proposed survey vessels in the
shallow-water section of the cable route
will achieve a maximum of 55 km per
0.0000
0.0000
0.0003
0.0000
0.2496
day during proposed HRG surveys. This
distance accounts for survey vessels
traveling at roughly 3 knots and
accounts for non-active survey periods.
Based on the maximum estimated
distance to the Level B harassment
threshold of 141 m (Table 6) and the
maximum estimated daily track line
distance of 110 km, an area of 31.1 km2
would be ensonified to the Level B
harassment threshold each day in the
Lease Area and deep-water section of
the cable route during Mayflower’s
proposed surveys. During 90 days of
anticipated survey activity over the four
month period (June through September),
approximately 22.5 days of survey
activity are expected each month, for an
average of 699.4 km2 ensonified to the
Level B harassment threshold in the
Lease Area and deep-water section of
the cable route each month of survey
activities.
Similarly, based on the maximum
estimated distance to the Level B
harassment threshold of 141 m (Table 6)
and the maximum estimated daily track
line distance of 55 km, an area of 15.6
km2 would be ensonified to the Level B
July
August
0.0000
0.0000
0.0002
0.0000
0.0281
September
0.0000
0.0000
0.0006
0.0000
0.0120
0.0000
0.0000
0.0009
0.0000
0.0245
harassment threshold each day in the
shallow-water section of the cable route.
During 125 days of anticipated survey
activity over the four month period
(June through September),
approximately 31.3 days of survey
activity (split among two vessels) are
expected each month, for an average of
486.6 km2 ensonified to the Level B
harassment threshold in the shallowwater section of the cable route each
month of survey activities.
As described above, this is a
conservative estimate as it assumes the
HRG sources that result in the greatest
isopleth distances to the Level B
harassment threshold would be
operated at all times during all 215
vessel days.
The estimated numbers of marine
mammals that may be taken by Level B
harassment were calculated by
multiplying the monthly density for
each species in each survey area (Table
7 and 8) by the respective monthly
ensonified area within each survey
section. The results were then summed
to determine the total estimated take
(Table 9).
TABLE 9—NUMBERS OF POTENTIAL INCIDENTAL TAKE OF MARINE MAMMALS PROPOSED FOR AUTHORIZATION AND
PROPOSED TAKES AS A PERCENTAGE OF POPULATION
Calculated take by survey
region
Lease area
and
deep-water
cable route
jbell on DSKJLSW7X2PROD with NOTICES2
Species
Fin whale ..................................................
Humpback whale .....................................
Minke whale .............................................
North Atlantic right whale .........................
Sei whale .................................................
Atlantic white-sided dolphin .....................
Bottlenose dolphin ...................................
Harbor porpoise .......................................
Pilot whale ................................................
Risso’s dolphin .........................................
Common dolphin ......................................
Sperm whale ............................................
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Shallow-water
cable route
8.3
2.9
3.4
0.9
0.3
109.3
115.7
36.4
18.4
1.7
276.3
0.8
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Total
calculated
takes by
level B
harassment
0.6
0.2
0.2
0
0
1.4
622.6
7
0
0
1
0
Fmt 4701
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Proposed
takes by
level A
harassment
8.9
3.1
3.6
0.9
0.3
110.7
738.3
43.4
18.4
1.7
277.2
0.8
E:\FR\FM\27MYN2.SGM
Proposed
takes by
level B
harassment b
0
0
0
0
0
0
0
0
0
0
0
0
27MYN2
9
4
4
c3
c2
111
739
44
19
b6
278
c2
Total proposed
instances of
take as a
percentage of
population a
0.3
0.2
0.1
0.8
0.4
0.1
1.0
0.1
0.1
0.1
0.2
0.0
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TABLE 9—NUMBERS OF POTENTIAL INCIDENTAL TAKE OF MARINE MAMMALS PROPOSED FOR AUTHORIZATION AND
PROPOSED TAKES AS A PERCENTAGE OF POPULATION—Continued
Calculated take by survey
region
Lease area
and
deep-water
cable route
Species
Seals (harbor and gray) ...........................
Shallow-water
cable route
40.4
Total
calculated
takes by
level B
harassment
152.8
Proposed
takes by
level A
harassment
193.2
Proposed
takes by
level B
harassment b
0
194
Total proposed
instances of
take as a
percentage of
population a
0.7
a Calculations
of percentage of stock taken are based on the best available abundance estimate as shown in Table 3. In most cases the best
available abundance estimate is provided by Roberts et al. (2016, 2017, 2018), when available, to maintain consistency with density estimates
derived from Roberts et al. (2016, 2017, 2018). For bottlenose dolphins and seals, Roberts et al. (2016, 2017, 2018) provides only a single abundance estimate and does not provide abundance estimates at the stock or species level (respectively), so the abundance estimate used to estimate percentage of stock taken for bottlenose dolphins is derived from NMFS SARs (Hayes et al., 2019). For seals, NMFS proposes to authorize
194 takes of seals as a guild by Level B harassment and assumes take could occur to either species. For the purposes of estimating percentage
of stock taken, the NMFS SARs abundance estimate for gray seals was used as the abundance of gray seals is lower than that of harbor seals
(Hayes et al., 2019).
b Proposed take equal to calculated take rounded up to next integer, or mean group size.
c Proposed take increased to mean group size (Palka et al., 2017; Kraus et al., 2016).
Using the take methodology approach
described above, the take estimates for
Risso’s dolphin, sei whale, North
Atlantic right whale, and sperm whale
were less than the average group sizes
estimated for these species (Table 9).
However, information on the social
structures of these species indicates
these species are likely to be
encountered in groups. Therefore it is
reasonable to conservatively assume
that one group of each of these species
will be taken during the proposed
survey. We therefore propose to
authorize the take of the average group
size for these species to account for the
possibility that the proposed survey
encounters a group of either of these
species (Table 9).
As described above, NMFS has
determined that the likelihood of take of
any marine mammals in the form of
Level A harassment occurring as a result
of the proposed surveys is so low as to
be discountable; therefore, we do not
propose to authorize take of any marine
mammals by Level A harassment.
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Proposed Mitigation
In order to issue an IHA under
Section 101(a)(5)(D) of the MMPA,
NMFS must set forth the permissible
methods of taking pursuant to the
activity, and other means of effecting
the least practicable impact on the
species or stock and its habitat, paying
particular attention to rookeries, mating
grounds, and areas of similar
significance, and on the availability of
the species or stock for taking for certain
subsistence uses (latter not applicable
for this action). NMFS regulations
require applicants for incidental take
authorizations to include information
about the availability and feasibility
(economic and technological) of
equipment, methods, and manner of
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conducting the activity or other means
of effecting the least practicable adverse
impact upon the affected species or
stocks and their habitat (50 CFR
216.104(a)(11)).
In evaluating how mitigation may or
may not be appropriate to ensure the
least practicable adverse impact on
species or stocks and their habitat, as
well as subsistence uses where
applicable, we carefully consider two
primary factors:
(1) The manner in which, and the
degree to which, the successful
implementation of the measure(s) is
expected to reduce impacts to marine
mammals, marine mammal species or
stocks, and their habitat. This considers
the nature of the potential adverse
impact being mitigated (likelihood,
scope, range). It further considers the
likelihood that the measure will be
effective if implemented (probability of
accomplishing the mitigating result if
implemented as planned), the
likelihood of effective implementation
(probability implemented as planned),
and;
(2) the practicability of the measures
for applicant implementation, which
may consider such things as cost,
impact on operations, and, in the case
of a military readiness activity,
personnel safety, practicality of
implementation, and impact on the
effectiveness of the military readiness
activity.
Proposed Mitigation Measures
NMFS proposes the following
mitigation measures be implemented
during Mayflower’s proposed marine
site characterization surveys.
Marine Mammal Exclusion Zones,
Buffer Zone and Monitoring Zone
Marine mammal exclusion zones (EZ)
would be established around the HRG
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survey equipment and monitored by
protected species observers (PSO)
during HRG surveys as follows:
• A 500-m EZ would be required for
North Atlantic right whales; and
• A 100-m EZ would be required for
all other marine mammals (with the
exception of certain small dolphin
species specified below).
If a marine mammal is detected
approaching or entering the EZs during
the proposed survey, the vessel operator
would adhere to the shutdown
procedures described below. In addition
to the EZs described above, PSOs would
visually monitor a 200 m Buffer Zone.
During use of acoustic sources with the
potential to result in marine mammal
harassment (i.e., anytime the acoustic
source is active, including ramp-up),
occurrences of marine mammals within
the Buffer Zone (but outside the EZs)
would be communicated to the vessel
operator to prepare for potential
shutdown of the acoustic source. The
Buffer Zone is not applicable when the
EZ is greater than 100 meters. PSOs
would also be required to observe a
500-m Monitoring Zone and record the
presence of all marine mammals within
this zone. In addition, any marine
mammals observed within 141 m of the
active HRG equipment operating at or
below 180 kHz would be documented
by PSOs as taken by Level B
harassment. The zones described above
would be based upon the radial distance
from the active equipment (rather than
being based on distance from the vessel
itself).
Visual Monitoring
A minimum of one NMFS-approved
PSO 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
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to and during nighttime ramp-ups of
HRG equipment. Visual monitoring
would begin no less than 30 minutes
prior to ramp-up of HRG equipment and
would continue until 30 minutes after
use of the acoustic source ceases or until
30 minutes past sunset. PSOs would
establish and monitor the applicable
EZs, Buffer Zone and Monitoring Zone
as described above. Visual PSOs would
coordinate to ensure 360° visual
coverage around the vessel from the
most appropriate observation posts, and
would conduct visual observations
using binoculars and the naked eye
while free from distractions and in a
consistent, systematic, and diligent
manner. PSOs would estimate distances
to marine mammals located in
proximity to the vessel and/or relevant
using range finders. It would be the
responsibility of the Lead PSO on duty
to communicate the presence of marine
mammals as well as to communicate
and enforce the action(s) that are
necessary to ensure mitigation and
monitoring requirements are
implemented as appropriate. Position
data would be recorded using hand-held
or vessel global positioning system
(GPS) units for each confirmed marine
mammal sighting.
Pre-Clearance of the Exclusion Zones
Prior to initiating HRG survey
activities, Mayflower would implement
a 30-minute pre-clearance period.
During pre-clearance monitoring (i.e.,
before ramp-up of HRG equipment
begins), the Buffer Zone would also act
as an extension of the 100-m EZ in that
observations of marine mammals within
the 200-m Buffer Zone would also
preclude HRG operations from
beginning. During this period, PSOs
would ensure that no marine mammals
are observed within 200 m of the survey
equipment (500 m in the case of North
Atlantic right whales). HRG equipment
would not start up until this 200-m zone
(or, 500-m zone in the case of North
Atlantic right whales) is clear of marine
mammals for at least 30 minutes. The
vessel operator would notify a
designated PSO of the proposed start of
HRG survey equipment as agreed upon
with the lead PSO; the notification time
should not be less than 30 minutes prior
to the planned initiation of HRG
equipment order to allow the PSOs time
to monitor the EZs and Buffer Zone for
the 30 minutes of pre-clearance. A PSO
conducting pre-clearance observations
would be notified again immediately
prior to initiating active HRG sources.
If a marine mammal were observed
within the relevant EZs or Buffer Zone
during the pre-clearance period,
initiation of HRG survey equipment
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would not begin until the animal(s) has
been observed exiting the respective EZ
or Buffer Zone, or, until an additional
time period has elapsed with no further
sighting (i.e., minimum 15 minutes for
small odontocetes and seals, and 30
minutes for all other species). The preclearance requirement would include
small delphinoids that approach the
vessel (e.g., bow ride). PSOs would also
continue to monitor the zone for 30
minutes after survey equipment is shut
down or survey activity has concluded.
Ramp-Up of Survey Equipment
When technically feasible, a ramp-up
procedure would be used for
geophysical survey equipment capable
of adjusting energy levels at the start or
re-start of survey activities. The rampup procedure would be used at the
beginning of HRG survey activities in
order to provide additional protection to
marine mammals near the Project Area
by allowing them to detect the presence
of the survey and vacate the area prior
to the commencement of survey
equipment operation at full power.
Ramp-up of the survey equipment
would not begin until the relevant EZs
and Buffer Zone has been cleared by the
PSOs, as described above. HRG
equipment would be initiated at their
lowest power output and would be
incrementally increased to full power. If
any marine mammals are detected
within the EZs or Buffer Zone prior to
or during ramp-up, the HRG equipment
would be shut down (as described
below).
Shutdown Procedures
If an HRG source is active and a
marine mammal is observed within or
entering a relevant EZ (as described
above) an immediate shutdown of the
HRG survey equipment would be
required. When shutdown is called for
by a PSO, the acoustic source would be
immediately deactivated and any
dispute resolved only following
deactivation. Any PSO on duty would
have the authority to delay the start of
survey operations or to call for
shutdown of the acoustic source if a
marine mammal is detected within the
applicable EZ. The vessel operator
would establish and maintain clear lines
of communication directly between
PSOs on duty and crew controlling the
HRG source(s) to ensure that shutdown
commands are conveyed swiftly while
allowing PSOs to maintain watch.
Subsequent restart of the HRG
equipment would only occur after the
marine mammal has either been
observed exiting the relevant EZ, or,
until an additional time period has
elapsed with no further sighting of the
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animal within the relevant EZ (i.e., 15
minutes for small odontocetes and seals,
and 30 minutes for large whales).
Upon implementation of shutdown,
the HRG source may be reactivated after
the marine mammal that triggered the
shutdown has been observed exiting the
applicable EZ (i.e., the animal is not
required to fully exit the Buffer Zone
where applicable) or, following a
clearance period of 15 minutes for small
odontocetes and seals and 30 minutes
for all other species with no further
observation of the marine mammal(s)
within the relevant EZ. If the HRG
equipment shuts down for brief periods
(i.e., less than 30 minutes) for reasons
other than mitigation (e.g., mechanical
or electronic failure) the equipment may
be re-activated as soon as is practicable
at full operational level, without 30
minutes of pre-clearance, only if PSOs
have maintained constant visual
observation during the shutdown and
no visual detections of marine mammals
occurred within the applicable EZs and
Buffer Zone during that time. For a
shutdown of 30 minutes or longer, or if
visual observation was not continued
diligently during the pause, preclearance observation is required, as
described above.
The shutdown requirement would be
waived for certain genera of small
delphinids (i.e., Delphinus,
Lagenorhynchus, and Tursiops) under
certain circumstances. If a delphinid(s)
from these genera is visually detected
approaching the vessel (i.e., to bow ride)
or towed survey equipment, shutdown
would not be required. If there is
uncertainty regarding identification of a
marine mammal species (i.e., whether
the observed marine mammal(s) belongs
to one of the delphinid genera for which
shutdown is waived), PSOs would use
best professional judgment in making
the decision to call for a shutdown.
If a species for which authorization
has not been granted, or, a species for
which authorization has been granted
but the authorized number of takes have
been met, approaches or is observed
within the area encompassing the Level
B harassment isopleth (141 m),
shutdown would occur.
Vessel Strike Avoidance
Vessel strike avoidance measures
would include, but would not be
limited to, the following, except under
circumstances when complying with
these requirements would put the safety
of the vessel or crew at risk:
• All vessel operators and crew will
maintain vigilant watch for cetaceans
and pinnipeds, and slow down or stop
their vessel to avoid striking these
protected species;
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• All survey vessels, regardless of
size, must observe a 10-knot speed
restriction in DMAs designated by
NMFS for the protection of North
Atlantic right whales from vessel
strikes. Note that this requirement
includes vessels, regardless of size, to
adhere to a 10 knot speed limit in
DMAs, not just vessels 65 ft or greater
in length;
• All vessel operators will reduce
vessel speed to 10 knots (18.5 km/hr) or
less when any large whale, any mother/
calf pairs, large assemblages of nondelphinoid cetaceans are observed near
(within 100 m (330 ft)) an underway
vessel;
• All vessels will maintain a
separation distance of 500 m (1,640 ft)
or greater from any sighted North
Atlantic right whale;
• If underway, vessels must steer a
course away from any sighted North
Atlantic right whale at 10 knots (18.5
km/hr) or less until the 500-m (1,640 ft)
minimum separation distance has been
established. If a North Atlantic right
whale is sighted in a vessel’s path, or
within 100 m (330 ft) to an underway
vessel, the underway vessel must reduce
speed and shift the engine to neutral.
Engines will not be engaged until the
North Atlantic right whale has moved
outside of the vessel’s path and beyond
100 m. If stationary, the vessel must not
engage engines until the North Atlantic
right whale has moved beyond 100 m;
• All vessels will maintain a
separation distance of 100 m (330 ft) or
greater from any sighted non-delphinoid
cetacean. If sighted, the vessel
underway must reduce speed and shift
the engine to neutral, and must not
engage the engines until the nondelphinoid cetacean has moved outside
of the vessel’s path and beyond 100 m.
If a survey vessel is stationary, the
vessel will not engage engines until the
non-delphinoid cetacean has moved out
of the vessel’s path and beyond 100 m;
• All vessels will maintain a
separation distance of 50 m (164 ft) or
greater from any sighted delphinoid
cetacean. Any vessel underway remain
parallel to a sighted delphinoid
cetacean’s course whenever possible,
and avoid excessive speed or abrupt
changes in direction. Any vessel
underway reduces vessel speed to 10
knots (18.5 km/hr) or less when pods
(including mother/calf pairs) or large
assemblages of delphinoid cetaceans are
observed. Vessels may not adjust course
and speed until the delphinoid
cetaceans have moved beyond 50 m
and/or the abeam of the underway
vessel;
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• All vessels will maintain a
separation distance of 50 m (164 ft) or
greater from any sighted pinniped; and
• All vessels underway will not
divert or alter course in order to
approach any whale, delphinoid
cetacean, or pinniped. Any vessel
underway will avoid excessive speed or
abrupt changes in direction to avoid
injury to the sighted cetacean or
pinniped.
Project-specific training will be
conducted for all vessel crew prior to
the start of survey activities.
Confirmation of the training and
understanding of the requirements will
be documented on a training course log
sheet. Signing the log sheet will certify
that the crew members understand and
will comply with the necessary
requirements throughout the survey
activities.
Passive Acoustic Monitoring
Vineyard Wind would also employ
passive acoustic monitoring (PAM) to
support monitoring during night time
operations to provide for acquisition of
species detections at night. While PAM
is not typically required by NMFS for
HRG surveys, it may a provide
additional benefit as a mitigation and
monitoring measure to further limit
potential exposure to underwater sound
at levels that could result in injury or
behavioral harassment.
Based on our evaluation of the
applicant’s proposed measures, as well
as other measures considered by NMFS,
NMFS has preliminarily determined
that the proposed mitigation measures
provide the means effecting the least
practicable impact on the affected
species or stocks and their habitat,
paying particular attention to rookeries,
mating grounds, and areas of similar
significance.
Proposed 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 such taking.
The MMPA implementing regulations at
50 CFR 216.104 (a)(13) indicate that
requests for authorizations must include
the suggested means of accomplishing
the necessary monitoring and reporting
that will result in increased knowledge
of the species and of the level of taking
or impacts on populations of marine
mammals that are expected to be
present in the proposed action area.
Effective reporting is critical both to
compliance as well as ensuring that the
most value is obtained from the required
monitoring.
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Monitoring and reporting
requirements prescribed by NMFS
should contribute to improved
understanding of one or more of the
following:
• Occurrence of marine mammal
species or stocks in the area in which
take is anticipated (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
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 other important
physical components of marine
mammal habitat); and
• Mitigation and monitoring
effectiveness.
Proposed Monitoring Measures
As described above, visual monitoring
would be performed by qualified and
NMFS-approved PSOs. Mayflower
would use independent, dedicated,
trained PSOs, meaning that the PSOs
must be employed by a third-party
observer provider, must have no tasks
other than to conduct observational
effort, collect data, and communicate
with and instruct relevant vessel crew
with regard to the presence of marine
mammals and mitigation requirements
(including brief alerts regarding
maritime hazards), and must have
successfully completed an approved
PSO training course appropriate for
their designated task. Mayflower would
provide resumes of all proposed PSOs
(including alternates) to NMFS for
review and approval prior to the start of
survey operations.
During survey operations (e.g., any
day on which use of an HRG source is
planned to occur), a minimum of one
PSO must be on duty and conducting
visual observations at all times on all
active survey vessels during daylight
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hours (i.e., from 30 minutes prior to
sunrise through 30 minutes following
sunset) and nighttime ramp-ups of HRG
equipment. Visual monitoring would
begin no less than 30 minutes prior to
initiation of HRG survey equipment and
would continue until one hour after use
of the acoustic source ceases or until 30
minutes past sunset. PSOs would
coordinate to ensure 360° visual
coverage around the vessel from the
most appropriate observation posts, and
would conduct visual observations
using binoculars and the naked eye
while free from distractions and in a
consistent, systematic, and diligent
manner. PSOs may be on watch for a
maximum of four consecutive hours
followed by a break of at least two hours
between watches and may conduct a
maximum of 12 hours of observation per
24-hour period. In cases where multiple
vessels are surveying concurrently, any
observations of marine mammals would
be communicated to PSOs on all survey
vessels.
PSOs would be equipped with
binoculars and have the ability to
estimate distances to marine mammals
located in proximity to the vessel and/
or exclusion zone using range finders.
Reticulated binoculars will also be
available to PSOs for use as appropriate
based on conditions and visibility to
support the monitoring of marine
mammals. Position data would be
recorded using hand-held or vessel GPS
units for each sighting. Observations
would take place from the highest
available vantage point on the survey
vessel. General 360-degree scanning
would occur during the monitoring
periods, and target scanning by the PSO
would occur when alerted of a marine
mammal presence.
During good conditions (e.g., daylight
hours; Beaufort sea state (BSS) 3 or less),
to the maximum extent practicable,
PSOs would conduct observations when
the acoustic source is not operating for
comparison of sighting rates and
behavior with and without use of the
acoustic source and between acquisition
periods. Any observations of marine
mammals by crew members aboard any
vessel associated with the survey would
be relayed to the PSO team.
Data on all PSO observations would
be recorded based on standard PSO
collection requirements. This would
include dates, times, and locations of
survey operations; dates and times of
observations, location and weather;
details of marine mammal sightings
(e.g., species, numbers, behavior); and
details of any observed marine mammal
take that occurs (e.g., noted behavioral
disturbances).
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Proposed Reporting Measures
Within 90 days after completion of
survey activities, a final technical report
will be provided to NMFS that fully
documents the methods and monitoring
protocols, summarizes the data recorded
during monitoring, summarizes the
number of marine mammals estimated
to have been taken during survey
activities (by species, when known),
summarizes the mitigation actions taken
during surveys (including what type of
mitigation and the species and number
of animals that prompted the mitigation
action, when known), and provides an
interpretation of the results and
effectiveness of all mitigation and
monitoring. Any recommendations
made by NMFS must be addressed in
the final report prior to acceptance by
NMFS.
In addition to the final technical
report, Mayflower will provide the
reports described below as necessary
during survey activities. In the
unanticipated event that Mayflower’s
activities lead to an injury (Level A
harassment) of a marine mammal,
Mayflower would immediately cease the
specified activities and report the
incident to the NMFS Office of
Protected Resources Permits and
Conservation Division and the NMFS
Northeast Regional Stranding
Coordinator. The report would include
the following information:
• Time, date, and location (latitude/
longitude) of the incident;
• Name and type of vessel involved;
• Vessel’s speed during and leading
up to the incident;
• Description of the incident;
• Status of all sound source use in the
24 hours preceding the incident;
• Water depth;
• Environmental conditions (e.g.,
wind speed and direction, Beaufort sea
state, cloud cover, and visibility);
• Description of all marine mammal
observations in the 24 hours preceding
the incident;
• Species identification or
description of the animal(s) involved;
• Fate of the animal(s); and
• Photographs or video footage of the
animal(s) (if equipment is available).
Activities would not resume until
NMFS is able to review the
circumstances of the event. NMFS
would work with Mayflower to
minimize reoccurrence of such an event
in the future. Mayflower would not
resume activities until notified by
NMFS.
In the event that Mayflower personnel
discover an injured or dead marine
mammal, Mayflower would report the
incident to the OPR Permits and
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Conservation Division and the NMFS
Northeast Regional Stranding
Coordinator as soon as feasible. The
report would 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.
In the unanticipated event of a ship
strike of a marine mammal by any vessel
involved in the activities covered by the
IHA, Mayflower would report the
incident to the NMFS OPR Permits and
Conservation Division and the NMFS
Northeast Regional Stranding
Coordinator as soon as feasible. The
report would 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).
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Negligible Impact Analysis and
Determination
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 an impact
determination. In addition to
considering estimates of the number of
marine mammals that might be ‘‘taken’’
through harassment, NMFS considers
other factors, such as the likely nature
of any responses (e.g., intensity,
duration), the context of any responses
(e.g., critical reproductive time or
location, migration), as well as effects
on habitat, and the likely effectiveness
of the 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 this analysis 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, or
ambient noise levels).
To avoid repetition, our analysis
applies to all the species listed in Table
3, given that NMFS expects the
anticipated effects of the proposed
survey to be similar in nature. NMFS
does not anticipate that serious injury or
mortality would result from HRG
surveys, even in the absence of
mitigation, and no serious injury or
mortality is authorized. As discussed in
the Potential Effects section, nonauditory physical effects and vessel
strike are not expected to occur. We
expect that potential takes would be in
the form of short-term Level B
behavioral harassment in the form of
temporary avoidance of the area or
decreased foraging (if such activity were
occurring), reactions that are considered
to be of low severity and with no lasting
biological consequences (e.g., Southall
et al., 2007). As described above, Level
A harassment is not expected to result
given the nature of the operations, the
anticipated size of the Level A
harassment zones, the density of marine
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mammals in the area, and the required
shutdown zones.
Effects on individuals that are taken
by Level B harassment, on the basis of
reports in the literature as well as
monitoring from other similar activities,
will likely be limited to reactions such
as increased swimming speeds,
increased surfacing time, or decreased
foraging (if such activity were
occurring). Most likely, individuals will
simply move away from the sound
source and temporarily avoid the area
where the survey is occurring. We
expect that any avoidance of the survey
area by marine mammals would be
temporary in nature and that any marine
mammals that avoid the survey area
during the survey activities would not
be permanently displaced. Even
repeated Level B harassment of some
small subset of an overall stock is
unlikely to result in any significant
realized decrease in viability for the
affected individuals, and thus would
not result in any adverse impact to the
stock as a whole.
Regarding impacts to marine mammal
habitat, prey species are mobile, and are
broadly distributed throughout the
Project Area and the footprint of the
activity is small; therefore, marine
mammals that may be temporarily
displaced during survey activities are
expected to be able to resume foraging
once they have moved away from areas
with disturbing levels of underwater
noise. Because of the availability of
similar habitat and resources in the
surrounding area the impacts to marine
mammals and the food sources that they
utilize are not expected to cause
significant or long-term consequences
for individual marine mammals or their
populations. The HRG survey
equipment itself will not result in
physical habitat disturbance. Avoidance
of the area around the HRG survey
activities by marine mammal prey
species is possible. However, any
avoidance by prey species would be
expected to be short term and
temporary.
ESA-listed species for which takes are
authorized are North Atlantic right, fin,
sei, and sperm whales, and these effects
are anticipated to be limited to lower
level behavioral effects. The proposed
survey is not anticipated to affect the
fitness or reproductive success of
individual animals. Since impacts to
individual survivorship and fecundity
are unlikely, the proposed survey is not
expected to result in population-level
effects for any ESA-listed species or
alter current population trends of any
ESA-listed species.
The status of the North Atlantic right
whale population is of heightened
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concern and, therefore, merits
additional analysis. NMFS has
rigorously assessed potential impacts to
right whales from this survey. We have
established a 500-m shutdown zone for
right whales which is precautionary
considering the Level B harassment
isopleth for the largest source utilized
(i.e., GeoMarine Geo-Source 400 tip
sparker) is estimated to be 141 m.
The proposed Project Area
encompasses or is in close proximity to
feeding BIAs for right whales (FebruaryApril), humpback whales (MarchDecember), fin whales (March-October),
and sei whales (May-November) as well
as a migratory BIA for right whales
(March-April and November-December.
Most of these feeding BIAs are extensive
and sufficiently large (705 km2 and
3,149 km2 for right whales; 47,701 km2
for humpback whales; 2,933 km2 for fin
whales; and 56,609 km2 for sei whales),
and the acoustic footprint of the
proposed survey is sufficiently small,
that feeding opportunities for these
whales would not be reduced
appreciably. Any whales temporarily
displaced from the proposed Project
Area would be expected to have
sufficient remaining feeding habitat
available to them, and would not be
prevented from feeding in other areas
within the biologically important
feeding habitat. In addition, any
displacement of whales from the BIA or
interruption of foraging bouts would be
expected to be temporary in nature.
Therefore, we do not expect impacts to
whales within feeding BIAs to to effect
the fitness of any large whales.
A migratory BIA for North Atlantic
right whales (effective March-April and
November-December) extends from
Massachusetts to Florida (LaBrecque, et
al., 2015). Off the south coast of
Massachusetts and Rhode Island, this
BIA extends from the coast to beyond
the shelf break. The fact that the spatial
acoustic footprint of the proposed
survey is very small relative to the
spatial extent of the available migratory
habitat means that right whale migration
is not expected to be impacted by the
proposed survey. Required vessel strike
avoidance measures will also decrease
risk of ship strike during migration.
NMFS is expanding the standard
avoidance measures by requiring that all
vessels, regardless of size, adhere to a 10
knot speed limit in any established
DMAs. Additionally, limited take by
Level B harassment of North Atlantic
right whales has been proposed as HRG
survey operations are required to shut
down at 500 m to minimize the
potential for behavioral harassment of
this species.
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As noted previously, there are several
active UMEs occurring in the vicinity of
Mayflower’s proposed surveys. Elevated
humpback whale mortalities have
occurred along the Atlantic coast from
Maine through Florida since January
2016. Of the cases examined,
approximately half had evidence of
human interaction (ship strike or
entanglement). 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
stable. Beginning in 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. This event does
not provide cause for concern regarding
population level impacts, as the likely
population abundance is greater than
20,000 whales. Elevated North Atlantic
right whale mortalities began in June
2017, primarily in Canada. Overall,
preliminary findings support human
interactions, specifically vessel strikes
or rope entanglements, as the cause of
death for the majority of the right
whales. Elevated numbers of harbor seal
and gray seal mortalities were first
observed in July 2018 and have
occurred across Maine, New Hampshire
and Massachusetts. Based on tests
conducted so far, the main pathogen
found in the seals is phocine distemper
virus although additional testing to
identify other factors that may be
involved in this UME are underway.
The UME does not yet provide cause for
concern regarding population-level
impacts to any of these stocks. For
harbor seals, the population abundance
is over 75,000 and annual M/SI (345) is
well below PBR (2,006) (Hayes et al.,
2018). For gray seals, the population
abundance in the United States is over
27,000, with an estimated abundance
including seals in Canada of
approximately 505,000, and abundance
is likely increasing in the U.S. Atlantic
EEZ as well as in Canada (Hayes et al.,
2018).
Direct physical interactions (ship
strikes and entanglements) appear to be
responsible for many of the UME
humpback and right whale mortalities
recorded. The proposed HRG survey
will require ship strike avoidance
measures which would minimize the
risk of ship strikes while fishing gear
and in-water lines will not be employed
as part of the survey. Furthermore, the
proposed activities are not expected to
promote the transmission of infectious
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disease among marine mammals. The
survey is not expected to result in the
deaths of any marine mammals or
combine with the effects of the ongoing
UMEs to result in any additional
impacts not analyzed here. Accordingly,
Mayflower did not request, and NMFS
is not proposing to authorize, take of
marine mammals by serious injury, or
mortality.
The required mitigation measures are
expected to reduce the number and/or
severity of takes by giving animals the
opportunity to move away from the
sound source before HRG survey
equipment reaches full energy and
preventing animals from being exposed
to sound levels that have the potential
to cause injury (Level A harassment)
and more severe Level B harassment
during HRG survey activities, even in
the biologically important areas
described above. No Level A harassment
is anticipated or authorized.
NMFS expects that takes would be in
the form of short-term Level B
behavioral harassment in the form of
brief startling reaction and/or temporary
vacating of the area, or decreased
foraging (if such activity were
occurring)—reactions that (at the scale
and intensity anticipated here) are
considered to be of low severity and
with no lasting biological consequences.
Since both the source and the marine
mammals are mobile, only a smaller
area would be ensonified by sound
levels that could result in take for only
a short period. Additionally, required
mitigation measures would reduce
exposure to sound that could result in
more severe behavioral harassment.
In summary and as described above,
the following factors primarily support
our preliminary determination that the
impacts resulting from this activity are
not expected to adversely affect the
species or stock through effects on
annual rates of recruitment or survival:
• No mortality or serious injury is
anticipated or proposed to be
authorized;
• No Level A harassment (PTS) is
anticipated;
• Any foraging interruptions are
expected to be short term and unlikely
to be cause significantly impacts;
• Impacts on marine mammal habitat
and species that serve as prey species
for marine mammals are expected to be
minimal and the alternate areas of
similar habitat value for marine
mammals are readily available;
• Take is anticipated to be primarily
Level B behavioral harassment
consisting of brief startling reactions
and/or temporary avoidance of the
Project Area;
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31881
• Survey activities would occur in
such a comparatively small portion of
the biologically important area for north
Atlantic right whale migration, that any
avoidance of the Project Area due to
activities would not affect migration. In
addition, mitigation measures to shut
down at 500 m to minimize potential for
Level B behavioral harassment would
limit both the number and severity of
take of the species;
• Similarly, due to the relatively
small footprint of the survey activities
in relation to the size of a biologically
important areas for right, humpback, fin,
and sei whales foraging, the survey
activities would not affect foraging
success of this species; and
• Proposed mitigation measures,
including visual monitoring and
shutdowns, are expected to minimize
the intensity of potential impacts to
marine mammals.
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
proposed monitoring and mitigation
measures, NMFS preliminarily finds
that the total marine mammal take from
the Mayflower’s proposed HRG surveys
will have a negligible impact on all
affected marine mammal species or
stocks.
Small Numbers
As noted above, only small numbers
of incidental take may be authorized
under Sections 101(a)(5)(A) and (D) of
the MMPA for specified activities other
than military readiness activities. The
MMPA does not define small numbers
and so, in practice, where estimated
numbers are available, NMFS compares
the number of individuals taken to the
most appropriate estimation of
abundance of the relevant species or
stock in our determination of whether
an authorization is limited to small
numbers of marine mammals.
Additionally, other qualitative factors
may be considered in the analysis, such
as the temporal or spatial scale of the
activities.
The numbers of marine mammals that
we authorize to be taken, for all species
and stocks, would be considered small
relative to the relevant stocks or
populations (less than one third of the
best available population abundance for
all species and stocks) (see Table 9). In
fact, the total amount of taking proposed
for authorization for all species is 1
percent or less for all affected stocks.
Based on the analysis contained
herein of the proposed activity
(including the proposed mitigation and
monitoring measures) and the
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Federal Register / Vol. 85, No. 102 / Wednesday, May 27, 2020 / Notices
anticipated take of marine mammals,
NMFS preliminarily finds that small
numbers of marine mammals will be
taken relative to the population size of
the affected species or stocks.
Unmitigable Adverse Impact Analysis
and Determination
There are no relevant subsistence uses
of the affected marine mammal stocks or
species implicated by this action.
Therefore, NMFS has 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.
jbell on DSKJLSW7X2PROD with NOTICES2
Endangered Species Act (ESA)
Section 7(a)(2) of the Endangered
Species Act of 1973 (16 U.S.C. 1531 et
seq.) requires that each Federal agency
insure that any action it authorizes,
funds, or carries out is not likely to
jeopardize the continued existence of
any endangered or threatened species or
result in the destruction or adverse
modification of designated critical
habitat. To ensure ESA compliance for
the issuance of IHAs, NMFS consults
internally, in this case with the NMFS
Greater Atlantic Regional Fisheries
Office (GARFO), whenever we propose
to authorize take for endangered or
threatened species.
The NMFS Office of Protected
Resources Permits and Conservation
Division is proposing to authorize the
incidental take of four species of marine
mammals listed under the ESA: The
North Atlantic right, fin, sei, and sperm
whale. The Permits and Conservation
Division has requested initiation of
Section 7 consultation with NMFS
GARFO for the issuance of this IHA.
NMFS will conclude the ESA section 7
consultation prior to reaching a
determination regarding the proposed
issuance of the authorization.
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Proposed Authorization
As a result of these preliminary
determinations, NMFS proposes to issue
an IHA to Mayflower for conducting
marine site characterization surveys
offshore of Massachusetts in the area of
the Commercial Lease of Submerged
Lands for Renewable Energy
Development on the Outer Continental
Shelf (OCS–A 0521) and along a
potential submarine cable route to
landfall at Falmouth, Massachusetts for
a period of one year from the date of
issuance, provided the previously
mentioned mitigation, monitoring, and
reporting requirements are incorporated.
A draft of the proposed IHA can be
found at https://
www.fisheries.noaa.gov/permit/
incidental-take-authorizations-undermarine-mammal-protection-act.
Request for Public Comments
We request comment on our analyses,
the proposed authorization, and any
other aspect of this Notice of Proposed
IHA for the proposed HRG survey. We
also request at this time comment on the
potential Renewal of this proposed IHA
as described in the paragraph below.
Please include with your comments any
supporting data or literature citations to
help inform decisions on the request for
this IHA or a subsequent Renewal IHA.
On a case-by-case basis, NMFS may
issue a one-year Renewal IHA following
notice to the public providing an
additional 15 days for public comments
when (1) up to another year of identical
or nearly identical, or nearly identical,
activities as described in the Specified
Activities section of this notice is
planned or (2) the activities as described
in the Specified Activities section of
this notice would not be completed by
the time the IHA expires and a Renewal
would allow for completion of the
activities beyond that described in the
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Sfmt 9990
Dates and Duration section of this
notice, provided all of the following
conditions are met:
• A request for renewal is received no
later than 60 days prior to the needed
Renewal IHA effective date (recognizing
that the Renewal IHA expiration date
cannot extend beyond one year from
expiration of the initial IHA);
• The request for renewal must
include the following:
(1) An explanation that the activities
to be conducted under the requested
Renewal IHA are identical to the
activities analyzed under the initial
IHA, are a subset of the activities, or
include changes so minor (e.g.,
reduction in pile size) that the changes
do not affect the previous analyses,
mitigation and monitoring
requirements, or take estimates (with
the exception of reducing the type or
amount of take); and
(2) A preliminary monitoring report
showing the results of the required
monitoring to date and an explanation
showing that the monitoring results do
not indicate impacts of a scale or nature
not previously analyzed or authorized;
and
• Upon review of the request for
Renewal, the status of the affected
species or stocks, and any other
pertinent information, NMFS
determines that there are no more than
minor changes in the activities, the
mitigation and monitoring measures
will remain the same and appropriate,
and the findings in the initial IHA
remain valid.
Dated: May 19, 2020.
Donna S. Wieting,
Director, Office of Protected Resources,
National Marine Fisheries Service.
[FR Doc. 2020–11203 Filed 5–26–20; 8:45 am]
BILLING CODE 3510–22–P
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Agencies
[Federal Register Volume 85, Number 102 (Wednesday, May 27, 2020)]
[Notices]
[Pages 31856-31882]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2020-11203]
[[Page 31855]]
Vol. 85
Wednesday,
No. 102
May 27, 2020
Part II
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 Site Characterization Surveys Off the
Coast of Massachusetts; Notice
Federal Register / Vol. 85, No. 102 / Wednesday, May 27, 2020 /
Notices
[[Page 31856]]
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DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
[RTID 0648-XA065]
Takes of Marine Mammals Incidental to Specified Activities;
Taking Marine Mammals Incidental to Site Characterization Surveys Off
the Coast of Massachusetts
AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and
Atmospheric Administration (NOAA), Commerce.
ACTION: Notice; proposed incidental harassment authorization; request
for comments on proposed authorization and possible renewal.
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SUMMARY: NMFS has received a request from Mayflower Wind Energy LLC
(Mayflower) for authorization to take marine mammals incidental to site
characterization surveys off the coast of Massachusetts in the area of
the Commercial Lease of Submerged Lands for Renewable Energy
Development on the Outer Continental Shelf (OCS-A 0521) and along a
potential submarine cable route to landfall at Falmouth, Massachusetts.
Pursuant to the Marine Mammal Protection Act (MMPA), NMFS is requesting
comments on its proposal to issue an incidental harassment
authorization (IHA) to incidentally take marine mammals during the
specified activities. NMFS is also requesting comments on a possible
one-year renewal that could be issued under certain circumstances and
if all requirements are met, as described in Request for Public
Comments at the end of this notice. NMFS will consider public comments
prior to making any final decision on the issuance of the requested
MMPA authorizations and agency responses will be summarized in the
final notice of our decision.
DATES: Comments and information must be received no later than June 26,
2020.
ADDRESSES: Comments should be addressed to Jolie Harrison, Chief,
Permits and Conservation Division, Office of Protected Resources,
National Marine Fisheries Service. Physical comments should be sent to
1315 East-West Highway, Silver Spring, MD 20910 and electronic comments
should be sent to [email protected].
Instructions: NMFS is not responsible for comments sent by any
other method, to any other address or individual, or received after the
end of the comment period. Comments received electronically, including
all attachments, must not exceed a 25-megabyte file size. Attachments
to electronic comments will be accepted in Microsoft Word or Excel or
Adobe PDF file formats only. All comments received are a part of the
public record and will generally be posted online at https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act without change. All personal identifying
information (e.g., name, address) voluntarily submitted by the
commenter may be publicly accessible. Do not submit confidential
business information or otherwise sensitive or protected information.
FOR FURTHER INFORMATION CONTACT: Amy Fowler, Office of Protected
Resources, NMFS, (301) 427-8401. Electronic copies of the application
and supporting documents, as well as a list of the references cited in
this document, may be obtained online at: https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act. In case of problems accessing these
documents, please call the contact listed above.
SUPPLEMENTARY INFORMATION:
Background
The MMPA prohibits the ``take'' of marine mammals, with certain
exceptions. Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361
et seq.) direct 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 specified
geographical region if certain findings are made and either regulations
are issued or, if the taking is limited to harassment, a notice of a
proposed incidental take authorization may be provided to the public
for review.
Authorization for incidental takings shall be granted if NMFS finds
that the taking will have a negligible impact on the species or
stock(s) and will not have an unmitigable adverse impact on the
availability of the species or stock(s) for taking for subsistence uses
(where relevant). Further, NMFS must prescribe the permissible methods
of taking and other ``means of effecting the least practicable adverse
impact'' on the affected species or stocks and their habitat, paying
particular attention to rookeries, mating grounds, and areas of similar
significance, and on the availability of the species or stocks for
taking for certain subsistence uses (referred to in shorthand as
``mitigation''); and requirements pertaining to the mitigation,
monitoring and reporting of the takings are set forth.
National Environmental Policy Act
To comply with the National Environmental Policy Act of 1969 (NEPA;
42 U.S.C. 4321 et seq.) and NOAA Administrative Order (NAO) 216-6A,
NMFS must review our proposed action (i.e., the issuance of an
incidental harassment authorization) with respect to potential impacts
on the human environment.
This action is consistent with categories of activities identified
in Categorical Exclusion B4 (incidental harassment authorizations with
no anticipated serious injury or mortality) of the Companion Manual for
NOAA Administrative Order 216-6A, which do not individually or
cumulatively have the potential for significant impacts on the quality
of the human environment and for which we have not identified any
extraordinary circumstances that would preclude this categorical
exclusion. Accordingly, NMFS has preliminarily determined that the
issuance of the proposed IHA qualifies to be categorically excluded
from further NEPA review.
We will review all comments submitted in response to this notice
prior to concluding our NEPA process or making a final decision on the
IHA request.
Summary of Request
On January 17, 2020, NMFS received a request from Mayflower for an
IHA to take marine mammals incidental to site characterization surveys
in the area of the Commercial Lease of Submerged Lands for Renewable
Energy Development on the Outer Continental Shelf (OCS-A 0521; Lease
Area) and a submarine export cable route connecting the Lease Area to
landfall in Falmouth, Massachusetts. A revised application was received
on April 9, 2020. NMFS deemed that request to be adequate and complete.
Mayflower's request is for take of a small number of 14 species of
marine mammals by Level B harassment only. Neither Mayflower nor NMFS
expects serious injury or mortality to result from this activity and,
therefore, an IHA is appropriate.
Description of Proposed Activity
Overview
Mayflower proposes to conduct marine site characterization surveys,
including high-resolution geophysical (HRG) and geotechnical surveys,
in the area of Commercial Lease of Submerged Lands for Renewable Energy
Development on the Outer Continental
[[Page 31857]]
Shelf #OCS-A 0521 (Lease Area) and along a potential submarine cable
route to landfall at Falmouth, Massachusetts.
The purpose of the proposed surveys is to acquire geotechnical and
HRG data on the bathymetry, seafloor morphology, subsurface geology,
environmental/biological sites, seafloor obstructions, soil conditions,
and locations of any man-made, historical, or archaeological resources
within the Lease Area and export cable route to support development of
offshore wind energy facilities. Up to three survey vessels may operate
concurrently as part of the proposed surveys, but the three vessels
will spend no more than a combined total of 215 days at sea. Underwater
sound resulting from Mayflower's proposed site characterization surveys
has the potential to result in incidental take of marine mammals in the
form of behavioral harassment.
Dates and Duration
The total duration of geophysical survey activities would be
approximately 215 survey-days. This schedule is based on 24-hour
operations in the offshore, deep-water portion of the Lease Area, and
12-hour operations in shallow-water and nearshore areas of the export
cable route. The surveys are expected to occur between June and
September 2020.
Specific Geographic Region
Mayflower's survey activities would occur in the Northwest Atlantic
Ocean approximately 60 kilometers (km) south of Martha's Vineyard,
Massachusetts. All survey effort would occur within U.S. Federal and
state waters. Surveys would occur within the Lease Area and along a
potential submarine cable route connecting the Lease Area and landfall
at Falmouth, Massachusetts (see Figure 1 in Mayflower's IHA
application).
Detailed Description of Specific Activity
Mayflower's proposed marine site characterization surveys include
HRG and geotechnical survey activities. These survey activities would
occur within the Lease Area and within an export cable route between
the Lease Area and Falmouth, Massachusetts. The Lease Area is
approximately 515.5 square kilometers (km\2\; 127,388 acres) and lies
approximately 20 nautical miles (38 km south-southwest of Nantucket.
Water depths in the Lease Area are approximately 38-62 meters (m). For
the purpose of this IHA the Lease Area and export cable route are
collectively referred to as the Project Area.
The proposed HRG and geotechnical survey activities are described
below.
Geotechnical Survey Activities
Mayflower's proposed geotechnical survey activities would include
the following:
Sample boreholes and vibracores to determine geological
and geotechnical characteristics of sediments; and
Seabed core penetration tests (CPTs) to determine
stratigraphy and in situ conditions of the sub-surface sediments.
Geotechnical investigation activities are anticipated to be
conducted from up to two vessels, each equipped with dynamic
positioning (DP) thrusters. Impacts to the seafloor from this equipment
will be limited to the minimal contact of the sampling equipment, and
inserted boring and probes.
In considering whether marine mammal harassment is an expected
outcome of exposure to a particular activity or sound source, NMFS
considers the nature of the exposure itself (e.g., the magnitude,
frequency, or duration of exposure), characteristics of the marine
mammals potentially exposed, and the conditions specific to the
geographic area where the activity is expected to occur (e.g., whether
the activity is planned in a foraging area, breeding area, nursery or
pupping area, or other biologically important area for the species). We
then consider the expected response of the exposed animal and whether
the nature and duration or intensity of that response is expected to
cause disruption of behavioral patterns (e.g., migration, breathing,
nursing, breeding, feeding, or sheltering) or injury.
Geotechnical survey activities would be conducted from drill ships
equipped with DP thrusters. DP thrusters would be used to position the
sampling vessel on station and maintain position at each sampling
location during the sampling activity. Sound produced through use of DP
thrusters is similar to that produced by transiting vessels and DP
thrusters are typically operated either in a similarly predictable
manner or used for short durations around stationary activities. NMFS
does not believe acoustic impacts from DP thrusters are likely to
result in take of marine mammals in the absence of activity- or
location-specific circumstances that may otherwise represent specific
concerns for marine mammals (i.e., activities proposed in area known to
be of particular importance for a particular species), or associated
activities that may increase the potential to result in take when in
concert with DP thrusters. In this case, we are not aware of any such
circumstances. Therefore, NMFS believes the likelihood of DP thrusters
used during the proposed geotechnical surveys resulting in harassment
of marine mammals to be so low as to be discountable. As DP thrusters
are not expected to result in take of marine mammals, these activities
are not analyzed further in this document.
Field studies conducted off the coast of Virginia to determine the
underwater noise produced by CPTs and borehole drilling found that
these activities did not result in underwater noise levels that
exceeded current thresholds for Level B harassment of marine mammals
(Kalapinski, 2015). Given the small size and energy footprint of CPTs
and boring cores, NMFS believes the likelihood that noise from these
activities would exceed the Level B harassment threshold at any
appreciable distance is so low as to be discountable. Therefore,
geotechnical survey activities, including CPTs, vibracores, and
borehole drilling, are not expected to result in harassment of marine
mammals and are not analyzed further in this document.
Geophysical Survey Activities
Mayflower has proposed that HRG survey activities would be
conducted continuously 24 hours per day in the deep-water portion of
the Project Area, and 12 hours per day in the shallow-water portion of
the survey area. Based on this operation schedule, the estimated total
duration of the proposed activities would be a combined total of 215
survey days. This includes 90 days of surveys in the Lease Area and
deep-water section of the export cable route, 95 days in the shallow-
water section of the cable route, and 30 days in the very shallow
section of the cable route (waters less than 5 m deep) (see Table 1).
These estimated durations include potential weather down time.
Table 1--Summary of Proposed HRG Survey Segments
------------------------------------------------------------------------
Duration
Survey area Operating schedule (survey days)
------------------------------------------------------------------------
Lease Area and deep-water section 24 hours/day........ 90
of cable route.
[[Page 31858]]
Shallow-water section of cable 12 hours/day 95
route. (daylight only).
Very shallow cable route.......... 12 hours/day 30
(daylight only).
---------------
All areas combined............ .................... 215
------------------------------------------------------------------------
The HRG survey activities will be supported by vessels of
sufficient size to accomplish the survey goals in each of the specified
survey areas. Surveys in each of the identified survey areas will be
executed by a single vessel during any given campaign (i.e., no more
than one survey vessel would operate in the Lease Area and deep-water
section of the cable route at any given time, but there may be one
survey vessel operating in the Lease Area and deep-water cable route,
one vessel in the shallow-water section of the cable route, and one
vessel in the very shallow waters of the cable route operating
concurrently, for a total of three vessels conducting HRG surveys). HRG
equipment will either by mounted to or towed behind the survey vessel
at a typical survey speed of approximately 3 knots (kn; 5.6 km per
hour). The geophysical survey activities proposed by Mayflower would
include the following:
Seafloor imaging (sidescan sonar) for seabed sediment
classification purposes, to identify natural and man-made acoustic
targets resting on the seafloor. The sonar device emits conical or fan-
shaped pulses down toward the seafloor in multiple beams at a wide
angle, perpendicular to the path of the sensor through the water. The
acoustic return of the pulses is recorded in a series of cross-track
slices, which can be joined to form an image of the sea bottom within
the swath of the beam. They are typically towed beside or behind the
vessel or from an autonomous vehicle;
Multibeam echosounder (MBES) to determine water depths and
general bottom topography. MBES sonar systems project sonar pulses in
several angled beams from a transducer mounted to a ship's hull. The
beams radiate out from the transducer in a fan-shaped pattern
orthogonally to the ship's direction;
Medium penetration sub-bottom profiler (sparkers) to map
deeper subsurface stratigraphy as needed. Sparkers create acoustic
pulses from 50 Hz to 4 kHz omni-directionally from the source that can
penetrate several hundred meters into the seafloor. Typically towed
behind the vessel with adjacent hydrophone arrays to receive the return
signals;
Parametric sub-bottom profiler to provide high data
density in sub-bottom profiles that are typically required for cable
routes, very shallow water, and archaeological surveys. Typically
mounted on the hull of the vessel or from a side pole; and
Ultra-short baseline (USBL) positioning and Global
Acoustic Positioning System (GAPS) to provide high accuracy ranges by
measuring the time between the acoustic pulses transmitted by the
vessel transceiver and the equipment transponder necessary to produce
the acoustic profile. It is a two-component system with a hull or pole
mounted transceiver and one to several transponders either on the
seabed or on the equipment.
Table 2 identifies the representative survey equipment that may be
used in support of planned geophysical survey activities that operate
below 180 kilohertz (kHz) and have the potential to cause acoustic
harassment to marine mammals. The make and model of the listed
geophysical equipment may vary depending on availability and the final
equipment choices will vary depending upon the final survey design,
vessel availability, and survey contractor selection. Geophysical
surveys are expected to use several equipment types concurrently in
order to collect multiple aspects of geophysical data along one
transect. Selection of equipment combinations is based on specific
survey objectives.
Table 2--Summary of HRG Survey Equipment Proposed for Use by Mayflower
--------------------------------------------------------------------------------------------------------------------------------------------------------
Pulse
HRG equipment category Specific HRG equipment Operating frequency Source level Beamwidth Typical pulse repetition
range (kHz) (dB rms) (degrees) duration (ms) rate (Hz)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Sparker............................ Geomarine Geo-Spark 800 J 0.25 to 5............. 203 180 3.4 2
system.
Sub-bottom profiler................ Edgetech 3100 with SB-2-16S 2 to 16............... 179 65 10 10
towfish.
Innomar SES-2000 Medium-100 85 to 115............. 241 2 2 40
Parametric.
--------------------------------------------------------------------------------------------------------------------------------------------------------
The deployment of HRG survey equipment, including the equipment
planned for use during Mayflower's proposed activity, produces sound in
the marine environment that has the potential to result in harassment
of marine mammals. Proposed mitigation, monitoring, and reporting
measures are described in detail later in this document (please see
Proposed Mitigation and Proposed Monitoring and Reporting).
Description of Marine Mammals in the Area of Specified Activities
Sections 3 and 4 of the application summarize available information
regarding status and trends, distribution and habitat preferences, and
behavior and life history, of the potentially affected species.
Additional information regarding population trends and threats may be
found in NMFS's Stock Assessment Reports (SARs; https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments) and more general information about these species
(e.g., physical and behavioral descriptions) may be found on NMFS's
[[Page 31859]]
website. (https://www.fisheries.noaa.gov/find-species).
Table 3 lists all species or stocks for which take is expected and
proposed to be authorized for this action, and summarizes information
related to the population or stock, including regulatory status under
the MMPA and ESA and potential biological removal (PBR), where known.
For taxonomy, we follow Committee on Taxonomy (2019). PBR is 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 (as described in NMFS's SARs). While no mortality is
anticipated or authorized here, PBR and annual serious injury and
mortality from anthropogenic sources are included here as gross
indicators of the status of the species and other threats.
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 or survey 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. All managed stocks in this region are assessed in
NMFS's U.S. Atlantic SARs. All values presented in Table 3 are the most
recent available at the time of publication and are available in the
2018 Atlantic and Gulf of Mexico Marine Mammal Stock Assessments (Hayes
et al., 2019a), available online at: www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports-region
or and draft 2019 Atlantic and Gulf of Mexico Marine Mammal Stock
Assessments (Hayes et al. 2019b) available online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/draft-marine-mammal-stock-assessment-reports.
Table 3--Marine Mammals Known To Occur in the Project Area That May Be Affected by Mayflower's Proposed Activity
--------------------------------------------------------------------------------------------------------------------------------------------------------
Stock abundance
ESA/MMPA (CV, Nmin, most
Common name Scientific name Stock status; recent abundance Predicted PBR \4\ Annual M/
strategic (Y/ survey) \2\ abundance \3\ SI \4\
N) \1\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Order Cetartiodactyla--Cetacea--Superfamily Mysticeti (baleen whales)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Balaenidae:
North Atlantic right whale.. Eubalaena glacialis Western North E/D; Y 428 (0; 418; n/a). 535 (0.45) *...... 0.9 5.56
Atlantic.
Family Balaenopteridae
(rorquals):
Humpback whale.............. Megaptera Gulf of Maine...... -/-; N 1,396 (0; 1,380; 1,637 (0.07) *.... 22 12.15
novaeangliae. See SAR).
Fin whale....................... Balaenoptera Western North E/D; Y 7,418 (0.25; 4,633 (0.08)...... 12 2.35
physalus. Atlantic. 6,029; See SAR).
Sei whale....................... Balaenoptera Nova Scotia........ E/D; Y 6292 (1.015; 717 (0.30) *...... 6.2 1
borealis. 3,098; see SAR)
236.
Minke whale..................... Balaenoptera....... Canadian East Coast -/-; N 24,202 (0.3; 2,112 (0.05) *.... 1189 8
acutorostrata...... 18,902; See SAR).
--------------------------------------------------------------------------------------------------------------------------------------------------------
Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Physeteridae:
Sperm whale................. Physeter NA................. E; Y 4349 (0.28;3,451; 5,353 (0.12)...... 6.9 0
macrocephalus. See SAR).
Family Delphinidae:
Long-finned pilot whale..... Globicephala melas. Western North -/-; Y 5,636 (0.63; 18,977 (0.11) \5\. 35 38
Atlantic. 3,464).
Bottlenose dolphin.......... Tursiops spp....... Western North -/-; N 62,851 (0.23; 97,476 (0.06) \5\. 591 28
Atlantic Offshore. 51,914; See SAR).
Common dolphin.............. Delphinus delphis.. Western North -/-; N 172,825 (0.21; 86,098 (0.12)..... 1,452 419
Atlantic. 145,216; See SAR).
Atlantic white-sided dolphin Lagenorhynchus Western North -/-; N 92,233 (0.71; 37,180 (0.07)..... 544 26
acutus. Atlantic. 54,433; See SAR).
Risso's dolphin............. Grampus griseus.... Western North -/-; N 35,493 (0.19; 7,732 (0.09)...... 303 54.3
Atlantic. 30,289; See SAR).
Family Phocoenidae (porpoises):
Harbor porpoise............. Phocoena phocoena.. Gulf of Maine/Bay -/-; N 95,543 (0.31; 45,089 (0.12) *... 851 217
of Fundy. 74,034; See SAR).
--------------------------------------------------------------------------------------------------------------------------------------------------------
Order Carnivora--Superfamily Pinnipedia
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Phocidae (earless seals):
Gray seal \6\............... Halichoerus grypus. Western North -/-; N 27,131 (0.19; N/A............... 1,389 5,688
Atlantic. 23,158, 2016).
Harbor seal................. Phoca vitulina..... Western North -/-; N 75,834 (0.15; N/A............... 345 333
Atlantic. 66,884, 2018).
--------------------------------------------------------------------------------------------------------------------------------------------------------
\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: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports-region/. CV is coefficient of variation; Nmin is the minimum estimate of stock abundance. In some cases, CV is not applicable
[[Page 31860]]
\3\ This information represents species- or guild-specific abundance predicted by recent habitat-based cetacean density models (Roberts et al., 2016,
2017, 2018). 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 abundance predictions as a point of reference. Total abundance estimates were produced by computing the mean
density of all pixels in the modeled area and multiplying by its area. 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 abundance.
\4\ Potential biological removal, 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 size (OSP). Annual M/SI, found in NMFS' SARs,
represent annual levels of human-caused mortality plus serious injury from all sources combined (e.g., commercial fisheries, subsistence hunting, ship
strike). Annual M/SI values often cannot be determined precisely and is in some cases presented as a minimum value. All M/SI values are as presented
in the draft 2019 SARs (Hayes et al., 2019).
\5\ 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, 2017, 2018) are based in part on available observational data which, in
some cases, is limited to genus or guild in terms of taxonomic definition. Roberts et al. (2016, 2017, 2018) produced density models to genus level
for Globicephala spp. and produced a density model for bottlenose dolphins that does not differentiate between offshore and coastal stocks.
\6\ 8 NMFS stock abundance estimate applies to U.S. population only, actual stock abundance is approximately 505,000.
As indicated above, all 14 species (with 14 managed stocks) in
Table 3 temporally and spatially co-occur with the activity to the
degree that take is reasonably likely to occur, and we have proposed
authorizing it. All species that could potentially occur in the
proposed survey areas are included in Table 4 of the IHA application.
However, the temporal and/or spatial occurrence of several species
listed in Table 4 in the IHA application is such that take of these
species is not expected to occur. The blue whale (Balaenoptera
musculus), Cuvier's beaked whale (Ziphius cavirostris), four species of
Mesoplodont beaked whale (Mesoplodon spp.), dwarf and pygmy sperm whale
(Kogia sima and Kogia breviceps), and striped dolphin (Stenella
coeruleoalba), typically occur further offshore than the Project Area,
while short-finned pilot whales (Globicephala macrorhynchus) and
Atlantic spotted dolphins (Stenella frontalis) are typically found
further south than the Project Area (Hayes et al., 2019b). There are
stranding records of harp seals (Pagophilus groenlandicus) in
Massachusetts, but the species typically occurs north of the Project
Area and appearances in Massachusetts usually occur between January and
May, outside of the proposed survey dates (Hayes et al., 2019b). As
take of these species is not anticipated as a result of the proposed
activities, these species are not analyzed further.
The following subsections provide additional information on the
biology, habitat use, abundance, distribution, and the existing threats
to the non-ESA-listed and ESA-listed marine mammals that are both
common in the waters of the outer continental shelf (OCS) of Southern
New England and have the likelihood of occurring, at least seasonally,
in the Project Area and are, therefore, expected to potentially be
taken by the proposed activities.
North Atlantic Right Whale
The Western Atlantic stock of North Atlantic right whales ranges
primarily from calving grounds in coastal waters of the southeastern
United States to feeding grounds in New England waters and the Canadian
Bay of Fundy, Scotian Shelf, and Gulf of St. Lawrence (Hayes et al.,
2019). Surveys indicate that there are seven areas where NARWs
congregate seasonally: The coastal waters of the southeastern United
States, the Great South Channel, Jordan Basin, Georges Basin along the
northeastern edge of Georges Bank, Cape Cod and Massachusetts Bays, the
Bay of Fundy, and the Roseway Basin on the Scotian Shelf (Hayes et al.
2018). The closest of these seven areas is the Great South Channel,
which lies east of the Project Area, though none of these areas
directly overlaps the Project Area.
NMFS has designated two critical habitat areas for the NARW under
the ESA: the Gulf of Maine/Georges Bank region, and the southeast
calving grounds from North Carolina to Florida. NMFS's regulations at
50 CFR part 224.105 designated nearshore waters of the Mid-Atlantic
Bight as Mid-Atlantic U.S. Seasonal Management Areas (SMA) for right
whales in 2008. SMAs were developed to reduce the threat of collisions
between ships and right whales around their migratory route and calving
grounds. All vessels greater than 19.8 m (65 ft) in overall length must
operate at speeds of 10 knots (5.1 m/s) or less within these areas
during specific time periods. The Lease Area is located approximately
15 km southeast of the Block Island Sound SMA, which is active between
November 1 and April 30 each year. The Great South Channel SMA lies to
the northeast of the Lease Area and is active April 1 to July 31. NOAA
Fisheries may also establish Dynamic Management Areas (DMAs) when and
where NARWs are sighted outside SMAs. DMAs are generally in effect for
two weeks. During this time, vessels are encouraged to avoid these
areas or reduce speeds to 10 knots (5.1 m/s) or less while transiting
through these areas.
LaBrecque et al. 2015 identified ``biologically important areas
(BIAs)'' for cetaceans on the U.S. East Coast, including reproductive,
feeding, and migratory areas, as well as areas where small and resident
populations reside. The Project Area is encompassed by a right whale
BIA for migration from March to April and from November to December. A
feeding BIA for right whales from April to June was identified
northeast of the Project Area, east of Cape Cod.
The western North Atlantic population demonstrated overall growth
of 2.8 percent per year from 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 1 percent per year (Pace et al.
2017). Between 1990 and 2015, calving rates varied substantially, with
low calving rates coinciding with all three periods of decline or no
growth (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. However, in 2019 at least seven right
whale calves were identified while ten calves have been recorded in
2020. Data indicates that the number of adult females fell from 200 in
2010 to 186 in 2015 while males fell from 283 to 272 in the same time
period (Pace et al., 2017). In addition, elevated North Atlantic right
whale mortalities have occurred since June 7, 2017. A total of 30
confirmed dead stranded whales (21 in Canada; 9 in the United States),
have been documented to date. This event has been declared an Unusual
Mortality Event (UME), with human interactions (i.e., fishery-related
entanglements and vessel strikes) identified as the most likely cause.
More information is available online at: https://www.fisheries.noaa.gov/national/marine-life-distress/2017-2019-north-atlantic-right-whale-unusual-mortality-event.
Humpback Whale
Humpback whales are found worldwide in all oceans. Humpback whales
were listed as endangered under the Endangered Species Conservation Act
(ESCA) in June 1970. In 1973, the ESA replaced the ESCA, and humpbacks
continued to be listed as endangered. NMFS recently evaluated
[[Page 31861]]
the status of the species, and on September 8, 2016, NMFS divided the
species into 14 distinct population segments (DPS), removed the current
species-level listing, and in its place listed four DPSs as endangered
and one DPS as threatened (81 FR 62259; September 8, 2016). The
remaining nine DPSs were not listed. The West Indies DPS, which is not
listed under the ESA, is the only DPS of humpback whale that is
expected to occur in the Project Area. The best estimate of population
abundance for the West Indies DPS is 12,312 individuals, as described
in the NMFS Status Review of the Humpback Whale under the Endangered
Species Act (Bettridge et al., 2015).
Humpback whales in the Gulf of Maine stock typically feed in the
waters between the Gulf of Maine and Newfoundland during spring,
summer, and fall, but have been observed feeding in other areas, such
as off the coast of New York (Sieswerda et al. 2015). Humpback whales
are frequently piscivorous when in New England waters, feeding on
herring (Clupea harengus), sand lance (Ammodytes spp.), and other small
fishes, as well as euphausiids in the northern Gulf of Maine (Paquet et
al. 1997). During winter, the majority of humpback whales from North
Atlantic feeding areas (including the Gulf of Maine) mate and calve in
the West Indies, where spatial and genetic mixing among feeding groups
occurs, though significant numbers of animals are found in mid- and
high-latitude regions at this time and some individuals have been
sighted repeatedly within the same winter season, indicating that not
all humpback whales migrate south every winter (Waring et al., 2017).
Kraus et al. (2016) observed humpback whales in the RI/MA & MA WEAs
and surrounding areas during all seasons. Humpback whales were observed
most often during spring and summer months, with a peak from April to
June. Calves were observed 10 times and feeding was observed 10 times
during the Kraus et al. (2016) study. That study also observed one
instance of courtship behavior. Although humpback whales were rarely
seen during fall and winter surveys, acoustic data indicate that this
species may be present within the Massachusetts Wind Energy Area (WEA)
year-round, with the highest rates of acoustic detections in winter and
spring (Kraus et al. 2016).
A humpback whale BIA for feeding has been identified northeast of
the Lease Area in the Gulf of Maine, Stellwagen Bank, and the Great
South Channel from March through December (LaBrecque et al., 2015).
Since January 2016, elevated humpback whale mortalities have
occurred along the Atlantic coast from Maine through Florida. The event
has been declared a UME. Partial or full necropsy examinations have
been conducted on approximately half of the 111 known cases. A portion
of the whales have shown evidence of pre-mortem vessel strike; however,
this finding is not consistent across all of the whales examined so
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. More detailed information is available at:
https://www.fisheries.noaa.gov/national/marine-life-distress/2016-2019-humpback-whale-unusual-mortality-event-along-atlantic-coast (accessed
January 9, 2020). Three previous UMEs involving humpback whales have
occurred since 2000, in 2003, 2005, and 2006.
Fin Whale
The fin whale is the second largest baleen whale and is widely
distributed in all the world's oceans, but is most abundant in
temperate and cold waters (Aguilar and Garc[iacute]a-Vernet 2018). Fin
whales are presumed to migrate seasonally between feeding and breeding
grounds, but their migrations are less well defined than for other
baleen whales. In the North Atlantic, some feeding areas have been
identified but there are no known wintering areas (Aguilar and
Garc[iacute]a-Vernet 2018). Fin whales are found in the summer from
Baffin Bay, Spitsbergen, and the Barents Sea south to North Carolina
and the coast of Portugal (Rice 1998). Apparently not all individuals
migrate, because in winter they have been sighted from Newfoundland to
the Gulf of Mexico and the Caribbean Sea, and from the Faroes and
Norway south to the Canary Islands (Rice 1998). Fin whales off the
eastern United States, Nova Scotia, and the southeastern coast of
Newfoundland are believed to constitute a single stock under the
present International Whaling Commission (IWC) management scheme
(Donovan 1991), which has been called the Western North Atlantic stock.
Kraus et al. (2016) suggest that, compared to other baleen whale
species, fin whales have a high multi-seasonal relative abundance in
the Rhode Island/Massachusetts and Massachusetts Wind Energy Areas (RI/
MA & MA WEAs) and surrounding areas. Fin whales were observed in the MA
WEA) in spring and summer. This species was observed primarily in the
offshore (southern) regions of the RI/MA & MA WEAs during spring and
was found closer to shore (northern areas) during the summer months
(Kraus et al. 2016). Calves were observed three times and feeding was
observed nine times during the Kraus et al. (2016) study. Although fin
whales were largely absent from visual surveys in the RI/MA & MA WEAs
in the fall and winter months (Kraus et al. 2016), acoustic data
indicated that this species was present in the RI/MA & MA WEAs during
all months of the year.
The main threats to fin whales are fishery interactions and vessel
collisions (Waring et al., 2017). New England waters represent a major
feeding ground for fin whales. The Lease Area is flanked by two BIAs
for feeding fin whales--the area to the northeast is considered a BIA
year-round, while the area off the tip of Long Island to the southwest
is a BIA from March to October (LaBrecque et al. 2015).
Sei Whale
Sei whales occur worldwide, with a preference for oceanic waters
over shelf waters (Horwood 2018). The Nova Scotia stock of sei whales
can be found in deeper waters of the continental shelf edge waters of
the northeastern United States and northeastward to south of
Newfoundland. NOAA Fisheries considers sei whales occurring from the
U.S. East Coast to Cape Breton, Nova Scotia, and east to 42[deg] W as
the Nova Scotia stock of sei whales (Waring et al. 2016; Hayes et al.
2018). In the Northwest Atlantic, it is speculated that the whales
migrate from south of Cape Cod along the eastern Canadian coast in June
and July, and return on a southward migration again in September and
October (Waring et al. 2014; 2017).
Spring is the period of greatest abundance in U.S. waters, with
sightings concentrated along the eastern margin of Georges Bank and
into the Northeast Channel area, and along the southwestern edge of
Georges Bank in the area of Hydrographer Canyon (Waring et al., 2015).
Kraus et al. (2016) observed sei whales in the RI/MA and MA WEAs and
surrounding areas only between the months of March and June during the
2011-2015 NLPSC aerial survey. The number of sei whale observations was
less than half that of other baleen whale species in the two seasons in
which sei whales were observed (spring and summer). This species
demonstrated a distinct seasonal habitat use pattern that was
consistent
[[Page 31862]]
throughout the study. Calves were observed three times and feeding was
observed four times during the Kraus et al. (2016) study. Sei whales
were not observed in the MA WEA and nearby waters during the 2010-2017
Atlantic Marine Assessment Program for Protected Species (AMAPPS)
shipboard and aerial surveys. However, there were observations during
the 2016 and 2017 summer surveys that were identified as being either a
fin or sei whale. A BIA for feeding for sei whales occurs east of the
Lease Area from May through November (LaBrecque et al. 2015).
Minke Whale
Minke whales have a cosmopolitan distribution that spans ice-free
latitudes (Stewart and Leatherwood 1985). The Canadian East Coast stock
can be found in the area from the western half of the Davis Strait (45
[deg]W) to the Gulf of Mexico (Waring et al., 2017). This species
generally occupies waters less than 100 m deep on the continental
shelf. There appears to be a strong seasonal component to minke whale
distribution in which spring to fall are times of relatively widespread
and common occurrence, and when the whales are most abundant in New
England waters, while during winter the species appears to be largely
absent (Waring et al., 2017).
Kraus et al. (2016) observed minke whales in the RI/MA & MA WEAs
and surrounding areas primarily from May to June. This species
demonstrated a distinct seasonal habitat usage pattern that was
consistent throughout the study. Though minke whales were observed in
spring and summer months in the MA WEA, they were only observed in the
lease areas in the spring. Minke whales were not observed between
October and February, but acoustic data indicate the presence of this
species in the proposed Project Area in winter months. A BIA for
feeding for minke whales occurs east of the Lease Area from March
through November (LaBrecque et al., 2015).
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. Partial or full
necropsy examinations have been conducted on more than 60 percent of
the 79 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. More information is available at: https://www.fisheries.noaa.gov/national/marine-life-distress/2017-2019-minke-whale-unusual-mortality-event-along-atlantic-coast.
Sperm Whale
The distribution of the sperm whale in the U.S. Exclusive Economic
Zone (EEZ) occurs on the continental shelf edge, over the continental
slope, and into mid-ocean regions (Waring et al. 2015). The basic
social unit of the sperm whale appears to be the mixed school of adult
females plus their calves and some juveniles of both sexes, normally
numbering 20-40 animals in all. Sperm whales are somewhat migratory;
however, their migrations are not as specific as seen in most of the
baleen whale species. In the North Atlantic, there appears to be a
general shift northward during the summer, but there is no clear
migration in some temperate areas (Rice 1989). In summer, the
distribution of sperm whales includes the area east and north of
Georges Bank and into the Northeast Channel region, as well as the
continental shelf (inshore of the 100-m isobath) south of New England.
In the fall, sperm whale occurrence south of New England on the
continental shelf is at its highest level, and there remains a
continental shelf edge occurrence in the mid-Atlantic bight. In winter,
sperm whales are concentrated east and northeast of Cape Hatteras.
Their distribution is typically associated with waters over the
continental shelf break and the continental slope and into deeper
waters (Whitehead et al. 1991). Sperm whale concentrations near drop-
offs and areas with strong currents and steep topography are correlated
with high productivity. These whales occur almost exclusively found at
the shelf break, regardless of season.
Kraus et al. (2016) observed sperm whales four times in the RI/MA &
MA WEAs during the summer and fall from 2011 to 2015. Sperm whales,
traveling singly or in groups of three or four, were observed three
times in August and September of 2012, and once in June of 2015.
Long-Finned Pilot Whale
Long-finned pilot whales are found from North Carolina and north to
Iceland, Greenland and the Barents Sea (Waring et al., 2016). They are
generally found along the edge of the continental shelf (a depth of 330
to 3,300 feet (100 to 1,000 meters)), choosing areas of high relief or
submerged banks in cold or temperate shoreline waters. In the western
North Atlantic, long-finned pilot whales are pelagic, occurring in
especially high densities in winter and spring over the continental
slope, then moving inshore and onto the shelf in summer and autumn
following squid and mackerel populations (Reeves et al. 2002). They
frequently travel into the central and northern Georges Bank, Great
South Channel, and Gulf of Maine areas during the late spring and
remain through early fall (May and October) (Payne and Heinemann 1993).
Note that long-finned and short-finned pilot whales overlap
spatially along the mid-Atlantic shelf break between New Jersey and the
southern flank of Georges Bank (Payne and Heinemann 1993, Hayes et al.
2017) Long-finned pilot whales have occasionally been observed stranded
as far south as South Carolina, and short-finned pilot whale have
stranded as far north as Massachusetts (Hayes et al. 2017). The
latitudinal ranges of the two species therefore remain uncertain.
However, south of Cape Hatteras, most pilot whale sightings are
expected to be short-finned pilot whales, while north of approximately
42[deg] N, most pilot whale sightings are expected to be long-finned
pilot whales (Hayes et al. 2017). Based on the distributions described
in Hayes et al. (2017), pilot whale sightings in the Project Area would
most likely be long-finned pilot whales.
Kraus et al. (2016) observed pilot whales infrequently in the RI/MA
& MA WEAs and surrounding areas. Effort-weighted average sighting rates
for pilot whales could not be calculated. No pilot whales were observed
during the fall or winter, and these species were only observed 11
times in the spring and three times in the summer.
Atlantic White-Sided Dolphin
White-sided dolphins are found in cold temperate and sub-polar
waters of the North Atlantic, primarily in continental shelf waters to
the 100-m depth contour from central West Greenland to North Carolina
(Waring et al., 2017). The Gulf of Maine stock is most common in
continental shelf waters from Hudson Canyon to Georges Bank, and in the
Gulf of Maine and lower Bay of Fundy. Sighting data indicate seasonal
shifts in distribution (Northridge et al., 1997). During January to
May, low numbers of white-sided dolphins are found from Georges Bank to
Jeffreys Ledge (off New Hampshire), with even lower numbers south of
Georges Bank, as documented by a few strandings collected on beaches of
Virginia to South Carolina. From June through September, large numbers
of white-sided dolphins are found from Georges Bank to the lower Bay of
Fundy. From October to December, white-sided dolphins occur at
intermediate densities from southern Georges Bank to southern Gulf of
Maine
[[Page 31863]]
(Payne and Heinemann 1990). Sightings south of Georges Bank,
particularly around Hudson Canyon, occur year round but at low
densities.
Kraus et al. (2016) suggest that Atlantic white-sided dolphins
occur infrequently in the RI/MA & MA WEAs and surrounding areas.
Effort-weighted average sighting rates for Atlantic white-sided
dolphins could not be calculated, because this species was only
observed on eight occasions throughout the duration of the study
(October 2011 to June 2015). No Atlantic white-sided dolphins were
observed during the winter months, and this species was only sighted
twice in the fall and three times in the spring and summer.
Common Dolphin
The common dolphin is one of the most abundant and widely
distributed cetaceans, occurring in warm temperate and tropical regions
worldwide from about 60[deg] N to 50[deg] S (Perrin 2018). These
dolphins occur in groups of hundreds or thousands of individuals and
often associate with pilot whales or other dolphin species (Perrin
2018). Until recently, short-beaked and long-beaked common dolphins
were thought to be separate species but evidence now suggests that this
character distinction is based on ecology rather than genetics (Perrin
2018) and the Committee on Taxonomy now recognizes a single species
with three subspecies of common dolphin. The common dolphins occurring
in the Project Area are expected to be short-beaked common dolphins
(Delphinus delphis delphis; Perrin 2018) and would belong to the
Western North Atlantic stock (Hayes et al., 2018).
In the North Atlantic, short-beaked common dolphins are commonly
found over the continental shelf between the 100-m and 2,000-m isobaths
and over prominent underwater topography and east to the mid-Atlantic
Ridge (Waring et al., 2016). This species is found between Cape
Hatteras and Georges Bank from mid-January to May, although they
migrate onto the northeast edge of Georges Bank in the fall where large
aggregations occur (Kenney and Vigness-Raposa 2009), where large
aggregations occur on Georges Bank in fall (Waring et al. 2007).
Kraus et al. (2016) suggested that short-beaked common dolphins
occur year-round in the RI/MA & MA WEAs and surrounding areas. Short-
beaked common dolphins were the most frequently observed small cetacean
species within the Kraus et al. (2016) study area. Short-beaked common
dolphins were observed in the RI/MA & MA WEAs in all seasons but were
most frequently observed during the summer months, with peak sightings
in June and August. Short-beaked common dolphins were observed in the
MA WEA and nearby waters during all seasons of the 2010-2017 AMAPPS
surveys.
Bottlenose Dolphin
There are two distinct bottlenose dolphin ecotypes in the western
North Atlantic: the coastal and offshore forms (Waring et al., 2015).
The migratory coastal morphotype resides in waters typically less than
65.6 ft (20 m) deep, along the inner continental shelf (within 7.5 km
(4.6 miles) of shore), around islands, and is continuously distributed
south of Long Island, New York into the Gulf of Mexico. This migratory
coastal population is subdivided into 7 stocks based largely upon
spatial distribution (Waring et al. 2015). Generally, the offshore
migratory morphotype is found exclusively seaward of 34 km (21 miles)
and in waters deeper than 34 m (111.5 feet). This morphotype is most
expected in waters north of Long Island, New York (Waring et al. 2017;
Hayes et al. 2017; 2018). Bottlenose dolphins encountered in the
Project Area would likely belong to the Western North Atlantic Offshore
stock (Hayes et al. 2018). It is possible that a few animals could be
from the Northern Migratory Coastal stock, but they generally do not
range farther north than New Jersey.
Kraus et al. (2016) observed common bottlenose dolphins during all
seasons within the RI/MA & MA WEAs. Common bottlenose dolphins were the
second most commonly observed small cetacean species and exhibited
little seasonal variability in abundance. Common bottlenose dolphins
were observed in the MA WEA and nearby waters during spring, summer,
and fall of the 2010-2017 AMAPPS surveys.
Risso's Dolphins
Risso's dolphins are distributed worldwide in tropical and
temperate seas (Jefferson et al., 2008, 2014), and in the Northwest
Atlantic occur from Florida to eastern Newfoundland (Leatherwood et al.
1976; Baird and Stacey 1991). Off the northeastern U.S. coast, Risso's
dolphins are distributed along the continental shelf edge from Cape
Hatteras northward to Georges Bank during spring, summer, and autumn
(CETAP 1982; Payne et al., 1984). In winter, the range is in the mid-
Atlantic Bight and extends outward into oceanic waters (Payne et al.,
1984).
Risso's dolphins appear to prefer steep sections of the continental
shelf edge and deep offshore waters 100-1,000 m deep (Hartman 2018).
They are deep divers, feeding primarily on deep mesopelagic cephalopods
such as squid, octopus, and cuttlefish, and likely forage at night
(Hartman 2018).
Kraus et al. (2016) results suggest that Risso's dolphins occur
infrequently in the RI/MA & MA WEAs and surrounding areas. Risso's
dolphins were observed in the MA WEA and nearby waters during spring
and summer of the 2010-2017 AMAPPS surveys.
Harbor Porpoise
The harbor porpoise inhabits cool temperate to subarctic waters of
the Northern Hemisphere, generally within shallow coastal waters of the
continental shelf but occasionally travel over deeper, offshore waters
(Jefferson et al., 2008). They are usually seen in small groups of one
to three but occasionally form much larger groups (Bj[oslash]rge and
Tolley 2018).
There are likely four populations in the western North Atlantic:
Gulf of Maine/Bay of Fundy, Gulf of St. Lawrence, Newfoundland, and
Greenland (Gaskin 1984, 1992; Hayes et al., 2019). In the Project Area,
only the Gulf of Maine/Bay of Fundy stock may be present. This stock is
found in U.S. and Canadian Atlantic waters and is concentrated in the
northern Gulf of Maine and southern Bay of Fundy region, generally in
waters less than 150 m deep (Waring et al., 2017). During fall
(October-December) and spring (April-June) harbor porpoises are widely
dispersed from New Jersey to Maine. During winter (January to March),
intermediate densities of harbor porpoises can be found in waters off
New Jersey to North Carolina, and lower densities are found in waters
off New York to New Brunswick, Canada. They are seen from the coastline
to deep waters (>1800 m; Westgate et al. 1998), although the majority
of the population is found over the continental shelf (Waring et al.,
2017).
Kraus et al. (2016) indicate that harbor porpoises occur within the
RI/MA & MA WEAs in fall, winter, and spring. Harbor porpoises were
observed in groups ranging in size from three to 15 individuals and
were primarily observed in the Kraus et al. (2016) study area from
November through May, with very few sightings during June through
September. Harbor porpoises were observed in the MA WEA and nearby
waters during spring and fall of the 2010-2017 AMAPPS surveys.
Harbor Seal
The harbor seal has a wide distribution throughout coastal waters
between 30[deg] N and ~80[deg] N (Teilmann and Galatius 2018). Harbor
seals are
[[Page 31864]]
year-round inhabitants of the coastal waters of eastern Canada and
Maine (Katona et al. 1993), and occur seasonally along the coasts from
southern New England to New Jersey from September through late May
(Barlas 1999; Katona et al., 1993; Schneider and Payne 1983; Schroeder
2000). A northward movement from southern New England to Maine and
eastern Canada occurs prior to the pupping season, which takes place
from mid-May through June (Kenney 1994; Richardson 1976; Whitman and
Payne 1990; Wilson 1978). Harbor seals are generally present in the
Project Area seasonally, from September through May (Hayes et al.,
2019).
Kraus et al. (2016) observed harbor seals in the RI/MA and MA WEAs
and surrounding areas during the 2011-2015 NLPSC aerial survey, but
this survey was designed to target large cetaceans so locations and
numbers of seal observations were not included in the study report.
Harbor seals have five major haulout sites in and near the RI/MA and MA
WEAs: Monomoy Island, the northwestern side of Nantucket Island, Nomans
Land, the north side of Gosnold Island, and the southeastern side of
Naushon Island (Payne and Selzer 1989). Harbor seals were observed in
the MA WEA and nearby waters during spring, summer, and fall of the
2010-2017 AMAPPS surveys.
Gray Seal
Gray seals are found throughout the temperate and subarctic waters
of the North Atlantic (King 1983). In the northwestern Atlantic, they
occur from Labrador sound to Massachusetts (King 1983). Gray seals
often haul out on remote, exposed islands, shoals, and unstable
sandbars (Jefferson et al., 2008). Though they spend most of their time
in coastal waters, gray seals can dive to depths of 300 m (984 ft) and
frequently forage on the outer continental shelf (Jefferson et al.,
2008).
Gray seals in the Project Area belong to the western North Atlantic
stock. The range for this stock is thought to be from New Jersey to
Labrador. Current population trends show that gray seal abundance is
likely increasing in the U.S. Atlantic EEZ (Waring et al., 2017).
Although the rate of increase is unknown, surveys conducted since their
arrival in the 1980s indicate a steady increase in abundance in both
Maine and Massachusetts (Waring et al., 2017). It is believed that
recolonization by Canadian gray seals is the source of the U.S.
population (Waring et al., 2017). In U.S. waters, gray seals currently
pup at four established colonies from late December to mid-February:
Muskeget and Monomoy Islands in Massachusetts, and Green and Seal
Islands in Maine (Hayes et al., 2019). Pupping was also observed in the
early 1980s on small islands in Nantucket-Vineyard Sound and since
2010, pupping has been documented at Nomans Island in Massachusetts
(Hayes et al., 2019). The distributions of individuals from different
breeding colonies overlap outside of the breeding season. Gray seals
may be present in the Project Area year-round (Hayes et al., 2018).
Since July 2018, elevated numbers of harbor seal and gray seal
mortalities have occurred across Maine, New Hampshire and
Massachusetts. This event has been declared a UME. Additionally, seals
showing clinical signs of stranding have occurred as far south as
Virginia, although not in elevated numbers. Therefore the UME
investigation now encompasses all seal strandings from Maine to
Virginia. Between July 1, 2018 and March 13, 2020, a total of 3,152
seal strandings have been recorded as part of this designated Northeast
Pinniped UME. Based on tests conducted so far, the main pathogen found
in the seals is phocine distemper virus. Additional testing to identify
other factors that may be involved in this UME are underway. More
information is available at: https://www.fisheries.noaa.gov/new-england-mid-atlantic/marine-life-distress/2018-2020-pinniped-unusual-mortality-event-along.
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). Subsequently, NMFS (2018) described
generalized hearing ranges for these marine mammal hearing groups.
Generalized hearing ranges were chosen based on the approximately 65
decibel (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. Marine mammal hearing
groups and their associated hearing ranges are provided in Table 4.
Table 4--Marine Mammal Hearing Groups (NMFS, 2018)
------------------------------------------------------------------------
Hearing group Generalized hearing range *
------------------------------------------------------------------------
Low-frequency (LF) cetaceans (baleen 7 Hz to 35 kHz.
whales).
Mid-frequency (MF) cetaceans 150 Hz to 160 kHz.
(dolphins, toothed whales, beaked
whales, bottlenose whales).
High-frequency (HF) cetaceans (true 275 Hz to 160 kHz.
porpoises, Kogia, river dolphins,
cephalorhynchid, Lagenorhynchus
cruciger & L. australis).
Phocid pinnipeds (PW) (underwater) 50 Hz to 86 kHz.
(true seals).
Otariid pinnipeds (OW) (underwater) 60 Hz to 39 kHz.
(sea lions and fur seals).
------------------------------------------------------------------------
* Represents the generalized hearing range for the entire group as a
composite (i.e., all species within the group), where individual
species' hearing ranges are typically not as broad. Generalized
hearing range chosen based on ~65 dB threshold from normalized
composite audiogram, with the exception for lower limits for LF
cetaceans (Southall et al. 2007) and PW pinniped (approximation).
The pinniped functional hearing group was modified from Southall et
al. (2007) on the basis of data indicating that phocid species have
consistently demonstrated an extended frequency range of hearing
compared to otariids,
[[Page 31865]]
especially in the higher frequency range (Hemil[auml] et al., 2006;
Kastelein et al., 2009; Reichmuth and Holt, 2013).
For more detail concerning these groups and associated frequency
ranges, please see NMFS (2018) for a review of available information.
Fourteen marine mammal species (12 cetacean and two pinniped (both
phocid) species) have the reasonable potential to co-occur with the
proposed survey activities. Of the cetacean species that may be
present, six are classified as low-frequency cetaceans (i.e., all
mysticete species), five are classified as mid-frequency cetaceans
(i.e., all delphinid and ziphiid species and the sperm whale), and one
is classified as high-frequency cetaceans (i.e., harbor porpoise).
Potential Effects of Specified Activities on Marine Mammals and Their
Habitat
This section includes a summary and discussion of the ways that
components of the specified activity may impact marine mammals and
their habitat. The Estimated Take by Incidental Harassment 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 Analysis and Determination section considers the
content of this section, the Estimated Take by Incidental Harassment
section, and the Proposed Mitigation section, to draw conclusions
regarding the likely impacts of these activities on the reproductive
success or survivorship of individuals and how those impacts on
individuals are likely to impact marine mammal species or stocks.
Description of Sound Sources
This section contains a brief technical background on sound, on the
characteristics of certain sound types, and on metrics used in this
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. For general
information on sound and its interaction with the marine environment,
please see, e.g., Au and Hastings (2008); Richardson et al. (1995).
Sound travels in waves, the basic components of which are
frequency, wavelength, velocity, and amplitude. Frequency is the number
of pressure waves that pass by a reference point per unit of time and
is measured in hertz (Hz) or cycles per second. Wavelength is the
distance between two peaks or corresponding points of a sound wave
(length of one cycle). Higher frequency sounds have shorter wavelengths
than lower frequency sounds, and typically attenuate (decrease) more
rapidly, except in certain cases in shallower water. Amplitude is the
height of the sound pressure wave or the ``loudness'' of a sound and 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)), and is a logarithmic unit that accounts for
large variations in amplitude; therefore, a relatively small change in
dB corresponds to large changes in sound pressure. 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. Root mean square is calculated by squaring
all of the sound amplitudes, averaging the squares, and then taking the
square root of the average. Root mean square accounts for both positive
and negative values; squaring the pressures makes all values positive
so that they may be accounted for in the summation of pressure levels
(Hastings and Popper, 2005). 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 in a stated frequency band over a stated
time interval or event, and considers both intensity and duration of
exposure. The per-pulse SEL is calculated over the time window
containing the entire pulse (i.e., 100 percent of the acoustic energy).
SEL is a cumulative metric; it can be accumulated over a single pulse,
or calculated over periods containing multiple pulses. Cumulative SEL
represents the total energy accumulated by a receiver over a defined
time window or during an event. Peak sound pressure (also referred to
as zero-to-peak sound pressure or 0-pk) 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.
When underwater objects vibrate or activity occurs, sound-pressure
waves are created. These waves alternately compress and decompress the
water as the sound wave travels. Underwater sound waves radiate in a
manner similar to ripples on the surface of a pond and may be either
directed in a beam or beams or may radiate in all directions
(omnidirectional sources). The compressions and decompressions
associated with sound waves are detected as changes in pressure by
aquatic life and man-made sound receptors such as hydrophones.
Even in the absence of sound from the specified activity, the
underwater environment is typically loud due to ambient sound, which is
defined as environmental background sound levels lacking a single
source or point (Richardson et al., 1995). The sound level of a region
is defined by the total acoustical energy being generated by known and
unknown sources. These sources may include physical (e.g., wind and
waves, earthquakes, ice, atmospheric sound), biological (e.g., sounds
produced by marine mammals, fish, and invertebrates), and anthropogenic
(e.g., vessels, dredging, construction) sound. A number of sources
contribute to ambient sound, including wind and waves, which are a main
source of naturally occurring ambient sound for frequencies between 200
hertz (Hz) and 50 kilohertz (kHz) (Mitson, 1995). In general, ambient
sound levels tend to increase with increasing wind speed and wave
height. Precipitation can become an important component of total sound
at frequencies above 500 Hz, and possibly down to 100 Hz during quiet
times. Marine mammals can contribute significantly to ambient sound
levels, as can some fish and snapping shrimp. The frequency band for
biological contributions is from approximately 12 Hz to over 100 kHz.
Sources of ambient sound related to human activity include
transportation (surface vessels), dredging and construction, oil and
gas drilling and production, geophysical surveys, sonar, and
explosions. Vessel noise typically dominates the total ambient sound
for frequencies between 20 and 300 Hz. In general, the frequencies of
anthropogenic sounds are below 1 kHz and, if higher frequency sound
levels are created, they attenuate rapidly.
The sum of the various natural and anthropogenic sound sources that
comprise ambient sound at any given location and time depends not only
on the source levels (as determined by current weather conditions and
levels of biological and human activity) but also on the ability of
sound to propagate through the environment. In turn, sound propagation
is dependent on the spatially and temporally varying properties of the
water column and sea floor, and is frequency-dependent. As a
[[Page 31866]]
result of the dependence on a large number of varying factors, ambient
sound levels can be expected to vary widely over both coarse and fine
spatial and temporal scales. Sound levels at a given frequency and
location can vary by 10-20 dB from day to day (Richardson et al.,
1995). The result is that, depending on the source type and its
intensity, sound from the specified activity may be a negligible
addition to the local environment or could form a distinctive signal
that may affect marine mammals.
Sounds are often considered to fall into one of two general types:
Pulsed and non-pulsed. The distinction between these two sound types is
important because they have differing potential to cause physical
effects, particularly with regard to hearing (e.g., Ward, 1997 in
Southall et al., 2007). Please see Southall et al. (2007) for an in-
depth discussion of these concepts. The distinction between these two
sound types is not always obvious, as certain signals share properties
of both pulsed and non-pulsed sounds. A signal near a source could be
categorized as a pulse, but due to propagation effects as it moves
farther from the source, the signal duration becomes longer (e.g.,
Greene and Richardson, 1988).
Pulsed sound sources (e.g., airguns, explosions, gunshots, sonic
booms, impact pile driving) 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.
Non-pulsed sounds can be tonal, narrowband, or broadband, brief or
prolonged, and may be either continuous or intermittent (ANSI, 1995;
NIOSH, 1998). Some of these non-pulsed sounds can be transient signals
of short duration but without the essential properties of pulses (e.g.,
rapid rise time). Examples of non-pulsed sounds include those produced
by vessels, aircraft, machinery operations such as drilling or
dredging, vibratory pile driving, and active sonar systems. The
duration of such sounds, as received at a distance, can be greatly
extended in a highly reverberant environment.
Potential Effects of Underwater Sound
For study-specific citations, please see that work. Anthropogenic
sounds cover a broad range of frequencies and sound levels and can have
a range of highly variable impacts on marine life, from none or minor
to potentially severe responses, depending on received levels, duration
of exposure, behavioral context, and various other factors. The
potential effects of underwater sound from active acoustic sources can
potentially result in one or more of the following: temporary or
permanent hearing impairment, non-auditory physical or physiological
effects, behavioral disturbance, stress, and masking (Richardson et
al., 1995; Gordon et al., 2004; Nowacek et al., 2007; Southall et al.,
2007; G[ouml]tz et al., 2009). The degree of effect is intrinsically
related to the signal characteristics, received level, distance from
the source, and duration of the sound exposure. In general, sudden,
high level sounds can cause hearing loss, as can longer exposures to
lower level sounds. Temporary or permanent loss of hearing will occur
almost exclusively for noise within an animal's hearing range.
Richardson et al. (1995) described zones of increasing intensity of
effect that might be expected to occur, in relation to distance from a
source and assuming that the signal is within an animal's hearing
range. First is the area within which the acoustic signal would be
audible (potentially perceived) to the animal but not strong enough to
elicit any overt behavioral or physiological response. The next zone
corresponds with the area where the signal is audible to the animal and
of sufficient intensity to elicit behavioral or physiological
responsiveness. Third is a zone within which, for signals of high
intensity, the received level is sufficient to potentially cause
discomfort or tissue damage to auditory or other systems. Overlaying
these zones to a certain extent is the area within which masking (i.e.,
when a sound interferes with or masks the ability of an animal to
detect a signal of interest that is above the absolute hearing
threshold) may occur; the masking zone may be highly variable in size.
We describe the more severe effects (i.e., certain non-auditory
physical or physiological effects) only briefly as we do not expect
that there is a reasonable likelihood that HRG surveys may result in
such effects (see below for further discussion). Potential effects from
impulsive sound sources can range in severity from effects such as
behavioral disturbance or tactile perception to physical discomfort,
slight injury of the internal organs and the auditory system, or
mortality (Yelverton et al., 1973). Non-auditory physiological effects
or injuries that theoretically might occur in marine mammals exposed to
high level underwater sound or as a secondary effect of extreme
behavioral reactions (e.g., change in dive profile as a result of an
avoidance reaction) caused by exposure to sound include neurological
effects, bubble formation, resonance effects, and other types of organ
or tissue damage (Cox et al., 2006; Southall et al., 2007; Zimmer and
Tyack, 2007; Tal et al., 2015). The activities considered here do not
involve the use of devices such as explosives or mid-frequency tactical
sonar that are associated with these types of effects.
Threshold Shift--Note that, in the following discussion, we refer
in many cases to a review article concerning studies of noise-induced
hearing loss conducted from 1996-2015 (i.e., Finneran, 2015). Marine
mammals exposed to high-intensity sound, or to lower-intensity sound
for prolonged periods, can experience hearing threshold shift (TS),
which is the loss of hearing sensitivity at certain frequency ranges
(Finneran, 2015). TS can be permanent (PTS), in which case the loss of
hearing sensitivity is not fully recoverable, or temporary (TTS), in
which case the animal's hearing threshold would recover over time
(Southall et al., 2007). Repeated sound exposure that leads to TTS
could cause PTS. In severe cases of PTS, there can be total or partial
deafness, while in most cases the animal has an impaired ability to
hear sounds in specific frequency ranges (Kryter, 1985).
When PTS occurs, there is physical damage to the sound receptors in
the ear (i.e., tissue damage), whereas TTS represents primarily tissue
fatigue and is reversible (Southall et al., 2007). In addition, other
investigators have suggested that TTS is within the normal bounds of
physiological variability and tolerance and does not represent physical
injury (e.g., Ward, 1997). Therefore, NMFS does not consider TTS to
constitute auditory injury.
Relationships between TTS and PTS thresholds have not been studied
in marine mammals, and there is no PTS data for cetaceans, but such
relationships are assumed to be similar to those in humans and other
terrestrial mammals. PTS typically occurs at exposure levels at least
several decibels above (a 40-dB threshold shift approximates PTS onset;
e.g., Kryter et al., 1966; Miller, 1974) that inducing mild TTS (a 6-dB
threshold shift approximates TTS onset; e.g., Southall
[[Page 31867]]
et al. 2007). Based on data from terrestrial mammals, a precautionary
assumption is that the PTS thresholds for impulse sounds (such as
impact pile driving pulses as received close to the source) are at
least 6 dB higher than the TTS threshold on a peak-pressure basis and
PTS cumulative sound exposure level thresholds are 15 to 20 dB higher
than TTS cumulative sound exposure level thresholds (Southall et al.,
2007). Given the higher level of sound or longer exposure duration
necessary to cause PTS as compared with TTS, it is considerably less
likely that PTS could occur.
TTS is the mildest form of hearing impairment that can occur during
exposure to sound (Kryter, 1985). While experiencing TTS, the hearing
threshold rises, and a sound must be at a higher level in order to be
heard. In terrestrial and marine mammals, TTS can last from minutes or
hours to days (in cases of strong TTS). In many cases, hearing
sensitivity recovers rapidly after exposure to the sound ends. Few data
on sound levels and durations necessary to elicit mild TTS have been
obtained for marine mammals.
Marine mammal hearing plays a critical role in communication with
conspecifics, and interpretation of environmental cues for purposes
such as predator avoidance and prey capture. Depending on the degree
(elevation of threshold in dB), duration (i.e., recovery time), and
frequency range of TTS, and the context in which it is experienced, TTS
can have effects on marine mammals ranging from discountable to
serious. For example, a marine mammal may be able to readily compensate
for a brief, relatively small amount of TTS in a non-critical frequency
range that occurs during a time where ambient noise is lower and there
are not as many competing sounds present. Alternatively, a larger
amount and longer duration of TTS sustained during time when
communication is critical for successful mother/calf interactions could
have more serious impacts.
Currently, TTS data only exist for four species of cetaceans
(bottlenose dolphin, beluga whale (Delphinapterus leucas), harbor
porpoise, and Yangtze finless porpoise (Neophocoena asiaeorientalis))
and three species of pinnipeds (northern elephant seal (Mirounga
angustirostris), harbor seal, and California sea lion (Zalophus
californianus)) exposed to a limited number of sound sources (i.e.,
mostly tones and octave-band noise) in laboratory settings (Finneran,
2015). TTS was not observed in trained spotted (Phoca largha) and
ringed (Pusa hispida) seals exposed to impulsive noise at levels
matching previous predictions of TTS onset (Reichmuth et al., 2016). In
general, harbor seals and harbor porpoises have a lower TTS onset than
other measured pinniped or cetacean species (Finneran, 2015).
Additionally, the existing marine mammal TTS data come from a limited
number of individuals within these species. There are no data available
on noise-induced hearing loss for mysticetes. For summaries of data on
TTS in marine mammals or for further discussion of TTS onset
thresholds, please see Southall et al. (2007), Finneran and Jenkins
(2012), Finneran (2015), and NMFS (2018).
Animals in the Project Area during the proposed survey are unlikely
to incur TTS due to the characteristics of the sound sources, which
include relatively low source levels and generally very short pulses
and duration of the sound. Even for high-frequency cetacean species
(e.g., harbor porpoises), which may have increased sensitivity to TTS
(Lucke et al., 2009; Kastelein et al., 2012b), individuals would have
to make a very close approach and also remain very close to vessels
operating these sources in order to receive multiple exposures at
relatively high levels, as would be necessary to cause TTS.
Intermittent exposures--as would occur due to the brief, transient
signals produced by these sources--require a higher cumulative SEL to
induce TTS than would continuous exposures of the same duration (i.e.,
intermittent exposure results in lower levels of TTS) (Mooney et al.,
2009a; Finneran et al., 2010). Moreover, most marine mammals would more
likely avoid a loud sound source rather than swim in such close
proximity as to result in TTS. Kremser et al. (2005) noted that the
probability of a cetacean swimming through the area of exposure when a
sub-bottom profiler emits a pulse is small--because if the animal was
in the area, it would have to pass the transducer at close range in
order to be subjected to sound levels that could cause TTS and would
likely exhibit avoidance behavior to the area near the transducer
rather than swim through at such a close range. Further, the restricted
beam shape of the majority of the geophysical survey equipment proposed
for use makes it unlikely that an animal would be exposed more than
briefly during the passage of the vessel.
Behavioral Effects--Behavioral disturbance may include a variety of
effects, including subtle changes in behavior (e.g., minor or brief
avoidance of an area or changes in vocalizations), more conspicuous
changes in similar behavioral activities, and more sustained and/or
potentially severe reactions, such as displacement from or abandonment
of high-quality habitat. Behavioral responses to sound are highly
variable and context-specific and any reactions depend on numerous
intrinsic and extrinsic factors (e.g., species, state of maturity,
experience, current activity, reproductive state, auditory sensitivity,
time of day), as well as the interplay between factors (e.g.,
Richardson et al., 1995; Wartzok et al., 2003; Southall et al., 2007;
Weilgart, 2007; Archer et al., 2010). Behavioral reactions can vary not
only among individuals but also within an individual, depending on
previous experience with a sound source, context, and numerous other
factors (Ellison et al., 2012), and can vary depending on
characteristics associated with the sound source (e.g., whether it is
moving or stationary, number of sources, distance from the source).
Please see Appendices B-C of Southall et al. (2007) for a review of
studies involving marine mammal behavioral responses to sound.
Habituation can occur when an animal's response to a stimulus wanes
with repeated exposure, usually in the absence of unpleasant associated
events (Wartzok et al., 2003). Animals are most likely to habituate to
sounds that are predictable and unvarying. It is important to note that
habituation is appropriately considered as a ``progressive reduction in
response to stimuli that are perceived as neither aversive nor
beneficial,'' rather than as, more generally, moderation in response to
human disturbance (Bejder et al., 2009). The opposite process is
sensitization, when an unpleasant experience leads to subsequent
responses, often in the form of avoidance, at a lower level of
exposure. As noted, behavioral state may affect the type of response.
For example, animals that are resting may show greater behavioral
change in response to disturbing sound levels than animals that are
highly motivated to remain in an area for feeding (Richardson et al.,
1995; NRC, 2003; Wartzok et al., 2003). Controlled experiments with
captive marine mammals have showed pronounced behavioral reactions,
including avoidance of loud sound sources (Ridgway et al., 1997;
Finneran et al., 2003). Observed responses of wild marine mammals to
loud pulsed sound sources (typically airguns or acoustic harassment
devices) have been varied but often consist of avoidance behavior or
other behavioral changes suggesting discomfort (Morton and Symonds,
2002; see also Richardson et al., 1995;
[[Page 31868]]
Nowacek et al., 2007). However, many delphinids approach low-frequency
airgun source vessels with no apparent discomfort or obvious behavioral
change (e.g., Barkaszi et al., 2012), indicating the importance of
frequency output in relation to the species' hearing sensitivity.
Available studies show wide variation in response to underwater
sound; therefore, it is difficult to predict specifically how any given
sound in a particular instance might affect marine mammals perceiving
the signal. If a marine mammal does react briefly to an underwater
sound by changing its behavior or moving a small distance, the impacts
of the change are unlikely to be significant to the individual, let
alone the stock or population. However, if a sound source displaces
marine mammals from an important feeding or breeding area for a
prolonged period, impacts on individuals and populations could be
significant (e.g., Lusseau and Bejder, 2007; Weilgart, 2007; NRC,
2005). However, there are broad categories of potential response, which
we describe in greater detail here, that include alteration of dive
behavior, alteration of foraging behavior, effects to breathing,
interference with or alteration of vocalization, avoidance, and flight.
Changes in dive behavior can vary widely and may consist of
increased or decreased dive times and surface intervals as well as
changes in the rates of ascent and descent during a dive (e.g., Frankel
and Clark, 2000; Costa et al., 2003; Ng and Leung, 2003; Nowacek et
al.; 2004; Goldbogen et al., 2013a, 2013b). Variations in dive behavior
may reflect interruptions in biologically significant activities (e.g.,
foraging) or they may be of little biological significance. The impact
of an alteration to dive behavior resulting from an acoustic exposure
depends on what the animal is doing at the time of the exposure and the
type and magnitude of the response.
Disruption of feeding behavior can be difficult to correlate with
anthropogenic sound exposure, so it is usually inferred by observed
displacement from known foraging areas, the appearance of secondary
indicators (e.g., bubble nets or sediment plumes), or changes in dive
behavior. As for other types of behavioral response, the frequency,
duration, and temporal pattern of signal presentation, as well as
differences in species sensitivity, are likely contributing factors to
differences in response in any given circumstance (e.g., Croll et al.,
2001; Nowacek et al.; 2004; Madsen et al., 2006; Yazvenko et al.,
2007). A determination of whether foraging disruptions incur fitness
consequences would require information on or estimates of the energetic
requirements of the affected individuals and the relationship between
prey availability, foraging effort and success, and the life history
stage of the animal.
Variations in respiration naturally vary with different behaviors
and alterations to breathing rate as a function of acoustic exposure
can be expected to co-occur with other behavioral reactions, such as a
flight response or an alteration in diving. However, respiration rates
in and of themselves may be representative of annoyance or an acute
stress response. Various studies have shown that respiration rates may
either be unaffected or could increase, depending on the species and
signal characteristics, again highlighting the importance in
understanding species differences in the tolerance of underwater noise
when determining the potential for impacts resulting from anthropogenic
sound exposure (e.g., Kastelein et al., 2001, 2005, 2006; Gailey et
al., 2007; Gailey et al., 2016).
Marine mammals vocalize for different purposes and across multiple
modes, such as whistling, echolocation click production, calling, and
singing. Changes in vocalization behavior in response to anthropogenic
noise can occur for any of these modes and may result from a need to
compete with an increase in background noise or may reflect increased
vigilance or a startle response. For example, in the presence of
potentially masking signals, humpback whales and killer whales have
been observed to increase the length of their songs (Miller et al.,
2000; Fristrup et al., 2003; Foote et al., 2004), while right whales
have been observed to shift the frequency content of their calls upward
while reducing the rate of calling in areas of increased anthropogenic
noise (Parks et al., 2007). In some cases, animals may cease sound
production during production of aversive signals (Bowles et al., 1994).
Avoidance is the displacement of an individual from an area or
migration path as a result of the presence of a sound or other
stressors, and is one of the most obvious manifestations of disturbance
in marine mammals (Richardson et al., 1995). For example, gray whales
are known to change direction--deflecting from customary migratory
paths--in order to avoid noise from airgun surveys (Malme et al.,
1984). Avoidance may be short-term, with animals returning to the area
once the noise has ceased (e.g., Bowles et al., 1994; Goold, 1996;
Stone et al., 2000; Morton and Symonds, 2002; Gailey et al., 2007).
Longer-term displacement is possible, however, which may lead to
changes in abundance or distribution patterns of the affected species
in the affected region if habituation to the presence of the sound does
not occur (e.g., Blackwell et al., 2004; Bejder et al., 2006; Teilmann
et al., 2006).
A flight response is a dramatic change in normal movement to a
directed and rapid movement away from the perceived location of a sound
source. The flight response differs from other avoidance responses in
the intensity of the response (e.g., directed movement, rate of
travel). Relatively little information on flight responses of marine
mammals to anthropogenic signals exist, although observations of flight
responses to the presence of predators have occurred (Connor and
Heithaus, 1996). The result of a flight response could range from
brief, temporary exertion and displacement from the area where the
signal provokes flight to, in extreme cases, marine mammal strandings
(Evans and England, 2001). However, it should be noted that response to
a perceived predator does not necessarily invoke flight (Ford and
Reeves, 2008), and whether individuals are solitary or in groups may
influence the response.
Behavioral disturbance can also impact marine mammals in more
subtle ways. Increased vigilance may result in costs related to
diversion of focus and attention (i.e., when a response consists of
increased vigilance, it may come at the cost of decreased attention to
other critical behaviors such as foraging or resting). These effects
have generally not been demonstrated for marine mammals, but studies
involving fish and terrestrial animals have shown that increased
vigilance may substantially reduce feeding rates (e.g., Beauchamp and
Livoreil, 1997; Fritz et al., 2002; Purser and Radford, 2011). In
addition, chronic disturbance can cause population declines through
reduction of fitness (e.g., decline in body condition) and subsequent
reduction in reproductive success, survival, or both (e.g., Harrington
and Veitch, 1992; Daan et al., 1996; Bradshaw et al., 1998). However,
Ridgway et al. (2006) reported that increased vigilance in bottlenose
dolphins exposed to sound over a five-day period did not cause any
sleep deprivation or stress effects.
Many animals perform vital functions, such as feeding, resting,
traveling, and socializing, on a diel cycle (24-hour cycle). Disruption
of such functions resulting from reactions to stressors such as sound
exposure are more likely to be significant if they last more than one
diel cycle or recur on subsequent
[[Page 31869]]
days (Southall et al., 2007). Consequently, a behavioral response
lasting less than one day and not recurring on subsequent days is not
considered particularly severe unless it could directly affect
reproduction or survival (Southall et al., 2007). Note that there is a
difference between multi-day substantive behavioral reactions and
multi-day anthropogenic activities. For example, just because an
activity lasts for multiple days does not necessarily mean that
individual animals are either exposed to activity-related stressors for
multiple days or, further, exposed in a manner resulting in sustained
multi-day substantive behavioral responses.
We expect that some marine mammals may exhibit behavioral responses
to the HRG survey activities in the form of avoidance of the area
during the activity, especially the naturally shy harbor porpoise,
while others such as delphinids might be attracted to the survey
activities out of curiosity. However, because the HRG survey equipment
operates from a moving vessel, and the maximum radius to the Level B
harassment threshold is relatively small, the area and time that this
equipment would be affecting a given location is very small. Further,
once an area has been surveyed, it is not likely that it will be
surveyed again, thereby reducing the likelihood of repeated impacts
within the Project Area.
We have also considered the potential for severe behavioral
responses such as stranding and associated indirect injury or mortality
from Mayflower's use of HRG survey equipment. Commenters on previous
IHAs involving HRG surveys have referenced a 2008 mass stranding of
approximately 100 melon-headed whales in a Madagascar lagoon system. An
investigation of the event indicated that use of a high-frequency
mapping system (12-kHz multibeam echosounder) was the most plausible
and likely initial behavioral trigger of the event, while providing the
caveat that there is no unequivocal and easily identifiable single
cause (Southall et al., 2013). The investigatory panel's conclusion was
based on (1) very close temporal and spatial association and directed
movement of the survey with the stranding event; (2) the unusual nature
of such an event coupled with previously documented apparent behavioral
sensitivity of the species to other sound types (Southall et al., 2006;
Brownell et al., 2009); and (3) the fact that all other possible
factors considered were determined to be unlikely causes. Specifically,
regarding survey patterns prior to the event and in relation to
bathymetry, the vessel transited in a north-south direction on the
shelf break parallel to the shore, ensonifying large areas of deep-
water habitat prior to operating intermittently in a concentrated area
offshore from the stranding site; this may have trapped the animals
between the sound source and the shore, thus driving them towards the
lagoon system. The investigatory panel systematically excluded or
deemed highly unlikely nearly all potential reasons for these animals
leaving their typical pelagic habitat for an area extremely atypical
for the species (i.e., a shallow lagoon system). Notably, this was the
first time that such a system has been associated with a stranding
event. The panel also noted several site- and situation-specific
secondary factors that may have contributed to the avoidance responses
that led to the eventual entrapment and mortality of the whales.
Specifically, shoreward-directed surface currents and elevated
chlorophyll levels in the area preceding the event may have played a
role (Southall et al., 2013). The report also notes that prior use of a
similar system in the general area may have sensitized the animals and
also concluded that, for odontocete cetaceans that hear well in higher
frequency ranges where ambient noise is typically quite low, high-power
active sonars operating in this range may be more easily audible and
have potential effects over larger areas than low frequency systems
that have more typically been considered in terms of anthropogenic
noise impacts. It is, however, important to note that the relatively
lower output frequency, higher output power, and complex nature of the
system implicated in this event, in context of the other factors noted
here, likely produced a fairly unusual set of circumstances that
indicate that such events would likely remain rare and are not
necessarily relevant to use of lower-power, higher-frequency systems
more commonly used for HRG survey applications. The risk of similar
events recurring is likely very low, given the extensive use of active
acoustic systems used for scientific and navigational purposes
worldwide on a daily basis and the lack of direct evidence of such
responses previously reported.
Stress Responses--An animal's perception of a threat may be
sufficient to trigger stress responses consisting of some combination
of behavioral responses, autonomic nervous system responses,
neuroendocrine responses, or immune responses (e.g., Seyle, 1950;
Moberg, 2000). In many cases, an animal's first and sometimes most
economical (in terms of energetic costs) response is behavioral
avoidance of the potential stressor. Autonomic nervous system responses
to stress typically involve changes in heart rate, blood pressure, and
gastrointestinal activity. These responses have a relatively short
duration and may or may not have a significant long-term effect on an
animal's fitness.
Neuroendocrine stress responses often involve the hypothalamus-
pituitary-adrenal system. Virtually all neuroendocrine functions that
are affected by stress--including immune competence, reproduction,
metabolism, and behavior--are regulated by pituitary hormones. Stress-
induced changes in the secretion of pituitary hormones have been
implicated in failed reproduction, altered metabolism, reduced immune
competence, and behavioral disturbance (e.g., Moberg, 1987; Blecha,
2000). Increases in the circulation of glucocorticoids are also equated
with stress (Romano et al., 2004).
The primary distinction between stress (which is adaptive and does
not normally place an animal at risk) and ``distress'' is the cost of
the response. During a stress response, an animal uses glycogen stores
that can be quickly replenished once the stress is alleviated. In such
circumstances, the cost of the stress response would not pose serious
fitness consequences. However, when an animal does not have sufficient
energy reserves to satisfy the energetic costs of a stress response,
energy resources must be diverted from other functions. This state of
distress will last until the animal replenishes its energetic reserves
sufficient to restore normal function.
Relationships between these physiological mechanisms, animal
behavior, and the costs of stress responses are well studied through
controlled experiments and for both laboratory and free-ranging animals
(e.g., Holberton et al., 1996; Hood et al., 1998; Jessop et al., 2003;
Krausman et al., 2004; Lankford et al., 2005). Stress responses due to
exposure to anthropogenic sounds or other stressors and their effects
on marine mammals have also been reviewed (Fair and Becker, 2000;
Romano et al., 2002b) and, more rarely, studied in wild populations
(e.g., Romano et al., 2002a). For example, Rolland et al. (2012) found
that noise reduction from reduced ship traffic in the Bay of Fundy was
associated with decreased stress in North Atlantic right whales. These
and other studies lead to a reasonable expectation that some marine
mammals will experience physiological stress responses upon exposure to
acoustic
[[Page 31870]]
stressors and that it is possible that some of these would be
classified as ``distress.'' In addition, any animal experiencing TTS
would likely also experience stress responses (NRC, 2003).
NMFS does not expect that the generally short-term, intermittent,
and transitory HRG activities would create conditions of long-term,
continuous noise and chronic acoustic exposure leading to long-term
physiological stress responses in marine mammals.
Auditory Masking--Sound can disrupt behavior through masking, or
interfering with, an animal's ability to detect, recognize, or
discriminate between acoustic signals of interest (e.g., those used for
intraspecific communication and social interactions, prey detection,
predator avoidance, navigation) (Richardson et al., 1995; Erbe et al.,
2016). Masking occurs when the receipt of a sound is interfered with by
another coincident sound at similar frequencies and at similar or
higher intensity, and may occur whether the sound is natural (e.g.,
snapping shrimp, wind, waves, precipitation) or anthropogenic (e.g.,
shipping, sonar, seismic exploration) in origin. The ability of a noise
source to mask biologically important sounds depends on the
characteristics of both the noise source and the signal of interest
(e.g., signal-to-noise ratio, temporal variability, direction), in
relation to each other and to an animal's hearing abilities (e.g.,
sensitivity, frequency range, critical ratios, frequency
discrimination, directional discrimination, age or TTS hearing loss),
and existing ambient noise and propagation conditions.
Under certain circumstances, marine mammals experiencing
significant masking could also be impaired from maximizing their
performance fitness in survival and reproduction. Therefore, when the
coincident (masking) sound is man-made, it may be considered harassment
if disrupting behavioral patterns. It is important to distinguish TTS
and PTS, which persist after the sound exposure, from masking, which
occurs during the sound exposure. Because masking (without resulting in
TS) is not associated with abnormal physiological function, it is not
considered a physiological effect, but rather a potential behavioral
effect.
The frequency range of the potentially masking sound is important
in determining any potential behavioral impacts. For example, low-
frequency signals may have less effect on high-frequency echolocation
sounds produced by odontocetes but are more likely to affect detection
of mysticete communication calls and other potentially important
natural sounds such as those produced by surf and some prey species.
The masking of communication signals by anthropogenic noise may be
considered as a reduction in the communication space of animals (e.g.,
Clark et al., 2009) and may result in energetic or other costs as
animals change their vocalization behavior (e.g., Miller et al., 2000;
Foote et al., 2004; Parks et al., 2007; Di Iorio and Clark, 2009; Holt
et al., 2009). Masking can be reduced in situations where the signal
and noise come from different directions (Richardson et al., 1995),
through amplitude modulation of the signal, or through other
compensatory behaviors (Houser and Moore, 2014). Masking can be tested
directly in captive species (e.g., Erbe, 2008), but in wild populations
it must be either modeled or inferred from evidence of masking
compensation. There are few studies addressing real-world masking
sounds likely to be experienced by marine mammals in the wild (e.g.,
Branstetter et al., 2013).
Masking affects both senders and receivers of acoustic signals and
can potentially have long-term chronic effects on marine mammals at the
population level as well as at the individual level. Low-frequency
ambient sound levels have increased by as much as 20 dB (more than
three times in terms of SPL) in the world's ocean from pre-industrial
periods, with most of the increase from distant commercial shipping
(Hildebrand, 2009). All anthropogenic sound sources, but especially
chronic and lower-frequency signals (e.g., from vessel traffic),
contribute to elevated ambient sound levels, thus intensifying masking.
Marine mammal communications would not likely be masked appreciably
by the HRG equipment given the directionality of the signals (for most
geophysical survey equipment types proposed for use (Table 1) and the
brief period when an individual mammal is likely to be within its beam.
Vessel Strike
Vessel strikes of marine mammals can cause significant wounds,
which may lead to the death of the animal. An animal at the surface
could be struck directly by a vessel, a surfacing animal could hit the
bottom of a vessel, or a vessel's propeller could injure an animal just
below the surface. The severity of injuries typically depends on the
size and speed of the vessel (Knowlton and Kraus 2001; Laist et al.,
2001; Vanderlaan and Taggart 2007).
The most vulnerable marine mammals are those that spend extended
periods of time at the surface in order to restore oxygen levels within
their tissues after deep dives (e.g., the sperm whale). In addition,
some baleen whales, such as the North Atlantic right whale, seem
generally unresponsive to vessel sound, making them more susceptible to
vessel collisions (Nowacek et al., 2004). These species are primarily
large, slow moving whales. Smaller marine mammals (e.g., bottlenose
dolphin) move quickly through the water column and are often seen
riding the bow wave of large ships. Marine mammal responses to vessels
may include avoidance and changes in dive pattern (NRC 2003). An
examination of all known ship strikes from all shipping sources
(civilian and military) indicates vessel speed is a principal factor in
whether a vessel strike results in death (Knowlton and Kraus 2001;
Laist et al., 2001; Jensen and Silber 2003; Vanderlaan and Taggart
2007). In assessing records with known vessel speeds, Laist et al.
(2001) found a direct relationship between the occurrence of a whale
strike and the speed of the vessel involved in the collision. The
authors concluded that most deaths occurred when a vessel was traveling
in excess of 24.1 km/h (14.9 mph; 13 kn). Given the slow vessel speeds
and predictable course necessary for data acquisition, ship strike is
unlikely to occur during the geophysical surveys. Marine mammals would
be able to easily avoid the survey vessel due to the slow vessel speed.
Further, Mayflower would implement measures (e.g., protected species
monitoring, vessel speed restrictions and separation distances; see
Proposed Mitigation) set forth in the BOEM lease to reduce the risk of
a vessel strike to marine mammal species in the Project Area.
Anticipated Effects on Marine Mammal Habitat
The proposed activities would not result in permanent impacts to
habitats used directly by marine mammals, but may have potential minor
and short-term impacts to food sources such as forage fish. The
proposed activities could affect acoustic habitat (see masking
discussion above), but meaningful impacts are unlikely. There are no
feeding areas, rookeries, or mating grounds known to be biologically
important to marine mammals within the proposed Project Area with the
exception of feeding BIAs for right, humpback, fin, and sei whales and
a migratory BIA for right whales which were described previously. The
HRG survey equipment will not contact the substrate and does not
represent a
[[Page 31871]]
source of pollution. Impacts to substrate or from pollution are
therefore not discussed further.
Effects to Prey--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.
Fish utilize the soundscape 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 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 noise 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 impulse 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). However, some studies have shown no or slight
reaction to impulse sounds (e.g., Pena et al., 2013; Wardle et al.,
2001; Jorgenson and Gyselman, 2009; Cott et al., 2012). More commonly,
though, the impacts of noise on fish are temporary.
We are not aware of any available literature on impacts to marine
mammal prey from sound produced by HRG survey equipment. However, as
the HRG survey equipment introduces noise to the marine environment,
there is the potential for it to result in avoidance of the area around
the HRG survey activities on the part of marine mammal prey. The
duration of fish avoidance of an area after HRG surveys depart the area
is unknown, but a rapid return to normal recruitment, distribution and
behavior is anticipated. In general, impacts to marine mammal prey
species are expected to be minor and temporary due to the expected
short daily duration of the proposed HRG survey, the fact that the
proposed survey is mobile rather than stationary, and the relatively
small areas potentially affected. The areas likely impacted by the
proposed activities are relatively small compared to the available
habitat in the Atlantic Ocean. Any behavioral avoidance by fish of the
disturbed area would still leave significantly large areas of fish and
marine mammal foraging habitat in the nearby vicinity. Based on the
information discussed herein, we conclude that impacts of the specified
activity are not likely to have more than short-term adverse effects on
any prey habitat or populations of prey species. Because of the
temporary nature of the disturbance, and the availability of similar
habitat and resources (e.g., prey species) in the surrounding area, 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. Effects to
habitat will not be discussed further in this document.
Estimated Take
This section provides an estimate of the number of incidental takes
proposed for authorization through this IHA, which will inform both
NMFS' consideration of ``small numbers'' and the negligible impact
determination.
Harassment is the only type of take expected to result from these
activities. 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).
Authorized takes would be by Level B harassment only in the form of
disruption of behavioral patterns for individual marine mammals
resulting from exposure to HRG sources. Based on the nature of the
activity and the anticipated effectiveness of the mitigation measures
(i.e., exclusion zones and shutdown measures), discussed in detail
below in Proposed Mitigation section, Level A harassment is neither
anticipated nor proposed to be authorized.
As described previously, no mortality is anticipated or proposed to
be authorized for this activity. Below we describe how the take is
estimated.
Generally speaking, we estimate take by considering: (1) Acoustic
thresholds above which NMFS believes the best available science
indicates marine mammals will be behaviorally harassed or incur some
degree of permanent hearing impairment; (2) the area or volume of water
that will be ensonified above these levels in a day; (3) the density or
occurrence of marine mammals within these ensonified areas; and, (4)
and the number of days of activities. We note that while these basic
factors can contribute to a basic calculation to provide an initial
prediction of takes, additional information that can qualitatively
inform take estimates is also sometimes available (e.g., previous
monitoring results or average group size). Below, we describe the
factors considered here in more detail and present the proposed take
estimate.
Acoustic Thresholds
Using the best available science, NMFS has developed acoustic
thresholds that identify the received level of underwater sound above
which exposed marine mammals would be reasonably expected to be
behaviorally harassed (equated to Level B harassment) or to incur PTS
of some degree (equated to Level A harassment).
Level B Harassment for non-explosive sources--Though significantly
driven by received level, the onset of behavioral disturbance from
anthropogenic noise exposure is also informed to varying degrees by
other factors related to the source (e.g., frequency, predictability,
duty cycle), the environment (e.g., bathymetry), and the receiving
animals (hearing, motivation, experience, demography, behavioral
context) and can be difficult to predict (Southall et al., 2007,
Ellison et al., 2012). Based on what the available science indicates
and the practical need to use a threshold based on a factor that is
both predictable and measurable for most activities, NMFS uses a
generalized acoustic threshold based on received level to estimate the
onset of behavioral harassment. NMFS predicts that marine mammals are
likely to be behaviorally
[[Page 31872]]
harassed in a manner we consider Level B harassment when exposed to
underwater anthropogenic noise above received levels of 160 dB re 1
[mu]Pa (rms) for impulsive and/or intermittent sources (e.g., impact
pile driving) and 120 dB rms for continuous sources (e.g., vibratory
driving). Mayflower's proposed activity includes the use of impulsive
sources (geophysical survey equipment), and therefore use of the 160 dB
re 1 [mu]Pa (rms) threshold is applicable.
Level A harassment for non-explosive sources--NMFS' Technical
Guidance for Assessing the Effects of Anthropogenic Sound on Marine
Mammal Hearing (Version 2.0) (Technical Guidance, 2018) identifies dual
criteria to assess auditory injury (Level A harassment) to five
different marine mammal groups (based on hearing sensitivity) as a
result of exposure to noise from two different types of sources
(impulsive or non-impulsive). The components of Mayflower's proposed
activity includes the use of impulsive sources.
Predicted distances to Level A harassment isopleths, which vary
based on marine mammal functional hearing groups were calculated. The
updated acoustic thresholds for impulsive sounds (such as HRG survey
equipment) contained in the Technical Guidance (NMFS, 2018) were
presented as dual metric acoustic thresholds using both
SELcum and peak sound pressure level metrics. As dual
metrics, NMFS considers onset of PTS (Level A harassment) to have
occurred when either one of the two metrics is exceeded (i.e., metric
resulting in the largest isopleth). The SELcum metric
considers both level and duration of exposure, as well as auditory
weighting functions by marine mammal hearing group.
These thresholds are provided in Table 5 below. The references,
analysis, and methodology used in the development of the thresholds are
described in NMFS 2018 Technical Guidance, which may be accessed at:
www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance.
Table 5--Thresholds Identifying the Onset of Permanent Threshold Shift
----------------------------------------------------------------------------------------------------------------
PTS onset acoustic thresholds * (Received Level)
Hearing group ------------------------------------------------------------------------
Impulsive Non-impulsive
----------------------------------------------------------------------------------------------------------------
Low-Frequency (LF) Cetaceans........... Cell 1: L pk,flat: 219 dB; Cell 2: LE,LF,24h: 199 dB.
L E,LF,24h: 183 dB.
Mid-Frequency (MF) Cetaceans........... Cell 3: Lpk,flat: 230 dB; Cell 4: LE,MF,24h: 198 dB.
LE,MF,24h: 185 dB.
High-Frequency (HF) Cetaceans.......... Cell 5: Lpk,flat: 202 dB; Cell 6: LE,HF,24h: 173 dB.
LE,HF,24h: 155 dB.
Phocid Pinnipeds (PW) (Underwater)..... Cell 7: Lpk,flat: 218 dB Cell 8: LE,PW,24h: 201 dB.
LE,PW,24h: 185 dB.
Otariid Pinnipeds (OW) (Underwater).... Cell 9: Lpk,flat: 232 dB; Cell 10: LE,OW,24h: 219 dB.
LE,OW,24h: 203 dB.
----------------------------------------------------------------------------------------------------------------
NMFS considers the data provided by Crocker and Fratantonio (2016)
to represent the best available information on source levels associated
with HRG equipment and therefore recommends that source levels provided
by Crocker and Fratantonio (2016) be incorporated in the method
described above to estimate isopleth distances to the Level B
harassment threshold. In cases when the source level for a specific
type of HRG equipment is not provided in Crocker and Fratantonio
(2016), NMFS recommends that either the source levels provided by the
manufacturer be used, or, in instances where source levels provided by
the manufacturer are unavailable or unreliable, a proxy from Crocker
and Fratantonio (2016) be used instead. Table 2 shows the HRG equipment
types that may be used during the proposed surveys and the sound levels
associated with those HRG equipment types. Tables 2 and 4 of Appendix B
in the IHA application shows the literature sources for the sound
source levels that are shown in Table 2 and that were incorporated into
the modeling of Level B isopleth distances to the Level B harassment
threshold.
Results of modeling using the methodology described above indicated
that, of the HRG survey equipment planned for use by Mayflower that has
the potential to result in harassment of marine mammals, sound produced
by the Geomarine Geo-Spark 400 tip sparker would propagate furthest to
the Level B harassment threshold (Table 6); therefore, for the purposes
of the exposure analysis, it was assumed the Geomarine Geo-Spark 400
tip sparker would be active during the entire duration of the surveys.
Thus the distance to the isopleth corresponding to the threshold for
Level B harassment for the Geomarine Geo-Spark 400 tip sparker
(estimated at 141 m; Table 6) was used as the basis of the take
calculation for all marine mammals. Note that this results in a
conservative estimate of the total ensonified area resulting from the
proposed activities as Mayflower may not operate the Geomarine Geo-
Spark 400 tip sparker during the entire proposed survey, and for any
survey segments in which it is not ultimately operated, the distance to
the Level B harassment threshold would be less than 141 m (Table 6).
However, as Mayflower cannot predict the precise number of survey days
that will require the use of the Geomarine Geo-Spark 400 tip sparker,
it was assumed that it would be operated during the entire duration of
the proposed surveys.
Table 6--Modeled Radial Distances From HRG Survey Equipment to Isopleths Corresponding to Level A and Level B Harassment Thresholds
--------------------------------------------------------------------------------------------------------------------------------------------------------
Radial distance to level A harassment threshold (m) * Radial distance
-------------------------------------------------------------------- to level B
harassment
Sound source threshold (m)
Low frequency Mid frequency High frequency Phocid pinnipeds -----------------
cetaceans cetaceans cetaceans (underwater) All marine
mammals
--------------------------------------------------------------------------------------------------------------------------------------------------------
Innomar SES-2000 Medium-100 Parametric............................ <1 <1 60 <1 116
[[Page 31873]]
Edgetech 2000-DSS................................................. <1 <1 3 <1 5
Geomarine Geo-Spark 400 tip sparker (800 Joules).................. <1 <1 8 <1 141
--------------------------------------------------------------------------------------------------------------------------------------------------------
* Distances to the Level A harassment threshold based on the larger of the dual criteria (peak SPL and SELcum) are shown. For all sources the SELcum
metric resulted in larger isopleth distances.
Predicted distances to Level A harassment isopleths, which vary
based on marine mammal functional hearing groups (Table 5), were also
calculated. The updated acoustic thresholds for impulsive sounds (such
as HRG survey equipment) contained in the Technical Guidance (NMFS,
2018) were presented as dual metric acoustic thresholds using both
cumulative sound exposure level (SELcum) and peak sound
pressure level metrics. As dual metrics, NMFS considers onset of PTS
(Level A harassment) to have occurred when either one of the two
metrics is exceeded (i.e., the metric resulting in the largest
isopleth). The SELcum metric considers both level and
duration of exposure, as well as auditory weighting functions by marine
mammal hearing group.
Modeling of distances to isopleths corresponding to the Level A
harassment threshold was performed for all types of HRG equipment
proposed for use with the potential to result in harassment of marine
mammals. Mayflower used a new model developed by JASCO to calculate
distances to Level A harassment isopleths based on both the peak SPL
and the SELcum metric. For the peak SPL metric, the model is
a series of equations that accounts for both seawater absorption and
HRG equipment beam patterns (for all HRG sources with beam widths
larger than 90[deg], it was assumed these sources were
omnidirectional). For the SELcum metric, a model was
developed that accounts for the hearing sensitivity of the marine
mammal group, seawater absorption, and beam width for downwards-facing
transducers. Details of the modeling methodology for both the peak SPL
and SELcum metrics are provided in Appendix A of the IHA
application. This model entails the following steps:
1. Weighted broadband source levels were calculated by assuming a
flat spectrum between the source minimum and maximum frequency,
weighted the spectrum according to the marine mammal hearing group
weighting function (NMFS 2018), and summed across frequency;
2. Propagation loss was modeled as a function of oblique range;
3. Per-pulse SEL was modeled for a stationary receiver at a fixed
distance off a straight survey line, using a vessel transit speed of
3.5 knots and source-specific pulse length and repetition rate. The
off-line distance is referred to as the closest point of approach (CPA)
and was performed for CPA distances between 1 m and 10 km. The survey
line length was modeled as 10 km long (analysis showed longer survey
lines increased SEL by a negligible amount). SEL is calculated as SPL +
10 log10 T/15 dB, where T is the pulse duration;
4. The SEL for each survey line was calculated to produce curves of
weighted SEL as a function of CPA distance; and
5. The curves from Step 4 above were used to estimate the CPA
distance to the impact criteria.
We note that in the modeling methods described above and in
Appendix A of the IHA application, sources that operate with a
repetition rate greater than 10 Hz were assessed with the non-impulsive
(intermittent) source criteria while sources with a repetition rate
equal to or less than 10 Hz were assessed with the impulsive source
criteria. NMFS does not necessarily agree with this step in the
modeling assessment, which results in nearly all HRG sources being
classified as impulsive; however, we note that the classification of
the majority of HRG sources as impulsive results in more conservative
modeling results. Thus, we have assessed the potential for Level A
harassment to result from the proposed activities based on the modeled
Level A zones with the acknowledgement that these zones are likely
conservative.
Modeled isopleth distances to Level A harassment thresholds for all
types of HRG equipment and all marine mammal functional hearing groups
are shown in Table 6. The dual criteria (peak SPL and
SELcum) were applied to all HRG sources using the modeling
methodology as described above, and the largest isopleth distances for
each functional hearing group were then carried forward in the exposure
analysis to be conservative. For all HRG sources, the SELcum
metric resulted in larger isopleth distances. Distances to the Level A
harassment threshold based on the larger of the dual criteria (peak SPL
and SELcum) are shown in Table 6.
Modeled distances to isopleths corresponding to the Level A
harassment threshold are very small (<1 m) for three of the four marine
mammal functional hearing groups that may be impacted by the proposed
activities (i.e., low frequency and mid frequency cetaceans, and phocid
pinnipeds; see Table 6). Based on the very small Level A harassment
zones for these functional hearing groups, the potential for species
within these functional hearing groups to be taken by Level A
harassment is considered so low as to be discountable. For harbor
porpoises (a high frequency specialist), the largest modeled distance
to the Level A harassment threshold for the high frequency functional
hearing group was 60 m (Table 6). However, as noted above, modeled
distances to isopleths corresponding to the Level A harassment
threshold are assumed to be conservative. Further, the Innomar source
uses a very narrow beam width (two degrees) and the distances to the
Level A harassment isopleths are eight meters or less for the other two
sources. Level A harassment would also be more likely to occur at close
approach to the sound source or as a result of longer duration exposure
to the sound source, and mitigation measures--including a 100-m
exclusion zone for harbor porpoises--are expected to minimize the
potential for close approach or longer duration exposure to active HRG
[[Page 31874]]
sources. In addition, harbor porpoises are a notoriously shy species
which is known to avoid vessels, and would also be expected to avoid a
sound source prior to that source reaching a level that would result in
injury (Level A harassment). Therefore, we have determined that the
potential for take by Level A harassment of harbor porpoises is so low
as to be discountable. As NMFS has determined that the likelihood of
take of any marine mammals in the form of Level A harassment occurring
as a result of the proposed surveys is so low as to be discountable, we
therefore do not propose to authorize the take by Level A harassment of
any marine mammals.
Marine Mammal Occurrence
In this section we provide the information about the presence,
density, or group dynamics of marine mammals that will inform the take
calculations.
The habitat-based density models produced by the Duke University
Marine Geospatial Ecology Laboratory (Roberts et al., 2016, 2017, 2018)
represent the best available information regarding marine mammal
densities in the proposed survey area. The density data presented by
Roberts et al. (2016, 2017, 2018) incorporates aerial and shipboard
line-transect survey data from NMFS and other organizations and
incorporates data from 8 physiographic and 16 dynamic oceanographic and
biological covariates, and controls for the influence of sea state,
group size, availability bias, and perception bias on the probability
of making a sighting. These density models were originally developed
for all cetacean taxa in the U.S. Atlantic (Roberts et al., 2016). In
subsequent years, certain models have been updated on the basis of
additional data as well as certain methodological improvements. Our
evaluation of the changes leads to a conclusion that these represent
the best scientific evidence available. More information, including the
model results and supplementary information for each model, is
available online at seamap.env.duke.edu/models/Duke-EC-GOM-2015/.
Marine mammal density estimates in the project area (animals/km\2\)
were obtained using these model results (Roberts et al., 2016, 2017,
2018). The updated models incorporate additional sighting data,
including sightings from the NOAA Atlantic Marine Assessment Program
for Protected Species (AMAPPS) surveys from 2010-2014 (NEFSC & SEFSC,
2011, 2012, 2014a, 2014b, 2015, 2016).
For the exposure analysis, density data from Roberts et al. (2016,
2017, 2018) were mapped using a geographic information system (GIS).
These data provide abundance estimates for species or species guilds
within 10 km x 10 km grid cells (100 km\2\) on a monthly or annual
basis, depending on the species. In order to select a representative
sample of grid cells in and near the Project Area, a 10-km wide
perimeter around the Lease Area and an 8-km wide perimeter around the
cable route were created in GIS (ESRI 2017). The perimeters were then
used to select grid cells near the Project Area containing the most
recent monthly or annual estimates for each species in the Roberts et
al. (2016, 2017, 2018) data. The average monthly abundance for each
species in each survey area (deep-water and shallow-water) was
calculated as the mean value of the grid cells within each survey
portion in each month (June through September), and then converted for
density (individuals/km\2\) by dividing by 100 km\2\ (Tables 7 and 8).
Roberts et al. (2018) produced density models for all seals and did
not differentiate by seal species. Because the seasonality and habitat
use by gray seals roughly overlaps with that of harbor seals in the
survey areas, it was assumed that modeled takes of seals could occur to
either of the respective species, thus the total number of modeled
takes for seals was applied to each species.
Table 7--Average Monthly Densities for Species in the Lease Area and Deep-Water Section of the Cable Route
----------------------------------------------------------------------------------------------------------------
Estimated monthly density (individuals/km2)
Species ---------------------------------------------------------------
June July August September
----------------------------------------------------------------------------------------------------------------
Fin whale....................................... 0.0032 0.0033 0.0029 0.0025
Humpback whale.................................. 0.0014 0.0011 0.0005 0.0011
Minke whale..................................... 0.0024 0.0010 0.0007 0.0008
North Atlantic right whale...................... 0.0012 0.0000 0.0000 0.0000
Sei whale....................................... 0.0002 0.0001 0.0000 0.0001
Atlantic white-sided dolphin.................... 0.0628 0.0446 0.0243 0.0246
Bottlenose dolphin.............................. 0.0249 0.0516 0.0396 0.0494
Harbor porpoise................................. 0.0188 0.0125 0.0114 0.0093
Pilot whale..................................... 0.0066 0.0066 0.0066 0.0066
Risso's dolphin................................. 0.0002 0.0005 0.0009 0.0007
Common dolphin.................................. 0.0556 0.0614 0.1069 0.1711
Sperm whale..................................... 0.0001 0.0004 0.0004 0.0002
Seals (harbor and gray)......................... 0.0260 0.0061 0.0033 0.0040
----------------------------------------------------------------------------------------------------------------
Table 8--Average Monthly Densities for Species in the Shallow-Water Section of the Cable Route
----------------------------------------------------------------------------------------------------------------
Estimated monthly density (individuals/km\2\)
Species ---------------------------------------------------------------
June July August September
----------------------------------------------------------------------------------------------------------------
Fin whale....................................... 0.0003 0.0003 0.0003 0.0003
Humpback whale.................................. 0.0001 0.0001 0.0000 0.0001
Minke whale..................................... 0.0002 0.0000 0.0000 0.0000
North Atlantic right whale...................... 0.0000 0.0000 0.0000 0.0000
Sei whale....................................... 0.0000 0.0000 0.0000 0.0000
Atlantic white-sided dolphin.................... 0.0010 0.0006 0.0005 0.0008
Bottlenose dolphin.............................. 0.2308 0.4199 0.3211 0.3077
Harbor porpoise................................. 0.0048 0.0023 0.0037 0.0036
[[Page 31875]]
Pilot whale..................................... 0.0000 0.0000 0.0000 0.0000
Risso's dolphin................................. 0.0000 0.0000 0.0000 0.0000
Common dolphin.................................. 0.0003 0.0002 0.0006 0.0009
Sperm whale..................................... 0.0000 0.0000 0.0000 0.0000
Seals (harbor and gray)......................... 0.2496 0.0281 0.0120 0.0245
----------------------------------------------------------------------------------------------------------------
Take Calculation and Estimation
Here we describe how the information provided above is brought
together to produce a quantitative take estimate.
In order to estimate the number of marine mammals predicted to be
exposed to sound levels that would result in harassment, radial
distances to predicted isopleths corresponding to harassment thresholds
are calculated, as described above. Those distances are then used to
calculate the area(s) around the HRG survey equipment predicted to be
ensonified to sound levels that exceed harassment thresholds. The area
estimated to be ensonified to relevant thresholds in a single day is
then calculated, based on areas predicted to be ensonified around the
HRG survey equipment and the estimated trackline distance traveled per
day by the survey vessel. Mayflower estimates that the proposed survey
vessel in the Lease Area and deep-water sections of the cable route
will achieve a maximum daily trackline of 110 km per day and the
proposed survey vessels in the shallow-water section of the cable route
will achieve a maximum of 55 km per day during proposed HRG surveys.
This distance accounts for survey vessels traveling at roughly 3 knots
and accounts for non-active survey periods.
Based on the maximum estimated distance to the Level B harassment
threshold of 141 m (Table 6) and the maximum estimated daily track line
distance of 110 km, an area of 31.1 km\2\ would be ensonified to the
Level B harassment threshold each day in the Lease Area and deep-water
section of the cable route during Mayflower's proposed surveys. During
90 days of anticipated survey activity over the four month period (June
through September), approximately 22.5 days of survey activity are
expected each month, for an average of 699.4 km\2\ ensonified to the
Level B harassment threshold in the Lease Area and deep-water section
of the cable route each month of survey activities.
Similarly, based on the maximum estimated distance to the Level B
harassment threshold of 141 m (Table 6) and the maximum estimated daily
track line distance of 55 km, an area of 15.6 km\2\ would be ensonified
to the Level B harassment threshold each day in the shallow-water
section of the cable route. During 125 days of anticipated survey
activity over the four month period (June through September),
approximately 31.3 days of survey activity (split among two vessels)
are expected each month, for an average of 486.6 km\2\ ensonified to
the Level B harassment threshold in the shallow-water section of the
cable route each month of survey activities.
As described above, this is a conservative estimate as it assumes
the HRG sources that result in the greatest isopleth distances to the
Level B harassment threshold would be operated at all times during all
215 vessel days.
The estimated numbers of marine mammals that may be taken by Level
B harassment were calculated by multiplying the monthly density for
each species in each survey area (Table 7 and 8) by the respective
monthly ensonified area within each survey section. The results were
then summed to determine the total estimated take (Table 9).
Table 9--Numbers of Potential Incidental Take of Marine Mammals Proposed for Authorization and Proposed Takes as a Percentage of Population
--------------------------------------------------------------------------------------------------------------------------------------------------------
Calculated take by survey
region Total Total proposed
-------------------------------- calculated Proposed takes Proposed takes instances of
Species Lease area and takes by by level A by level B take as a
deep-water Shallow-water level B harassment harassment \b\ percentage of
cable route cable route harassment population \a\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Fin whale............................................... 8.3 0.6 8.9 0 9 0.3
Humpback whale.......................................... 2.9 0.2 3.1 0 4 0.2
Minke whale............................................. 3.4 0.2 3.6 0 4 0.1
North Atlantic right whale.............................. 0.9 0 0.9 0 \c\ 3 0.8
Sei whale............................................... 0.3 0 0.3 0 \c\ 2 0.4
Atlantic white-sided dolphin............................ 109.3 1.4 110.7 0 111 0.1
Bottlenose dolphin...................................... 115.7 622.6 738.3 0 739 1.0
Harbor porpoise......................................... 36.4 7 43.4 0 44 0.1
Pilot whale............................................. 18.4 0 18.4 0 19 0.1
Risso's dolphin......................................... 1.7 0 1.7 0 \b\ 6 0.1
Common dolphin.......................................... 276.3 1 277.2 0 278 0.2
Sperm whale............................................. 0.8 0 0.8 0 \c\ 2 0.0
[[Page 31876]]
Seals (harbor and gray)................................. 40.4 152.8 193.2 0 194 0.7
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Calculations of percentage of stock taken are based on the best available abundance estimate as shown in Table 3. In most cases the best available
abundance estimate is provided by Roberts et al. (2016, 2017, 2018), when available, to maintain consistency with density estimates derived from
Roberts et al. (2016, 2017, 2018). For bottlenose dolphins and seals, Roberts et al. (2016, 2017, 2018) provides only a single abundance estimate and
does not provide abundance estimates at the stock or species level (respectively), so the abundance estimate used to estimate percentage of stock
taken for bottlenose dolphins is derived from NMFS SARs (Hayes et al., 2019). For seals, NMFS proposes to authorize 194 takes of seals as a guild by
Level B harassment and assumes take could occur to either species. For the purposes of estimating percentage of stock taken, the NMFS SARs abundance
estimate for gray seals was used as the abundance of gray seals is lower than that of harbor seals (Hayes et al., 2019).
\b\ Proposed take equal to calculated take rounded up to next integer, or mean group size.
\c\ Proposed take increased to mean group size (Palka et al., 2017; Kraus et al., 2016).
Using the take methodology approach described above, the take
estimates for Risso's dolphin, sei whale, North Atlantic right whale,
and sperm whale were less than the average group sizes estimated for
these species (Table 9). However, information on the social structures
of these species indicates these species are likely to be encountered
in groups. Therefore it is reasonable to conservatively assume that one
group of each of these species will be taken during the proposed
survey. We therefore propose to authorize the take of the average group
size for these species to account for the possibility that the proposed
survey encounters a group of either of these species (Table 9).
As described above, NMFS has determined that the likelihood of take
of any marine mammals in the form of Level A harassment occurring as a
result of the proposed surveys is so low as to be discountable;
therefore, we do not propose to authorize take of any marine mammals by
Level A harassment.
Proposed Mitigation
In order to issue an IHA under Section 101(a)(5)(D) of the MMPA,
NMFS must set forth the permissible methods of taking pursuant to the
activity, and other means of effecting the least practicable impact on
the species or stock and its habitat, paying particular attention to
rookeries, mating grounds, and areas of similar significance, and on
the availability of the species or stock for taking for certain
subsistence uses (latter not applicable for this action). NMFS
regulations require applicants for incidental take authorizations to
include information about the availability and feasibility (economic
and technological) of equipment, methods, and manner of conducting the
activity or other means of effecting the least practicable adverse
impact upon the affected species or stocks and their habitat (50 CFR
216.104(a)(11)).
In evaluating how mitigation may or may not be appropriate to
ensure the least practicable adverse impact on species or stocks and
their habitat, as well as subsistence uses where applicable, we
carefully consider two primary factors:
(1) The manner in which, and the degree to which, the successful
implementation of the measure(s) is expected to reduce impacts to
marine mammals, marine mammal species or stocks, and their habitat.
This considers the nature of the potential adverse impact being
mitigated (likelihood, scope, range). It further considers the
likelihood that the measure will be effective if implemented
(probability of accomplishing the mitigating result if implemented as
planned), the likelihood of effective implementation (probability
implemented as planned), and;
(2) the practicability of the measures for applicant
implementation, which may consider such things as cost, impact on
operations, and, in the case of a military readiness activity,
personnel safety, practicality of implementation, and impact on the
effectiveness of the military readiness activity.
Proposed Mitigation Measures
NMFS proposes the following mitigation measures be implemented
during Mayflower's proposed marine site characterization surveys.
Marine Mammal Exclusion Zones, Buffer Zone and Monitoring Zone
Marine mammal exclusion zones (EZ) would be established around the
HRG survey equipment and monitored by protected species observers (PSO)
during HRG surveys as follows:
A 500-m EZ would be required for North Atlantic right
whales; and
A 100-m EZ would be required for all other marine mammals
(with the exception of certain small dolphin species specified below).
If a marine mammal is detected approaching or entering the EZs
during the proposed survey, the vessel operator would adhere to the
shutdown procedures described below. In addition to the EZs described
above, PSOs would visually monitor a 200 m Buffer Zone. During use of
acoustic sources with the potential to result in marine mammal
harassment (i.e., anytime the acoustic source is active, including
ramp-up), occurrences of marine mammals within the Buffer Zone (but
outside the EZs) would be communicated to the vessel operator to
prepare for potential shutdown of the acoustic source. The Buffer Zone
is not applicable when the EZ is greater than 100 meters. PSOs would
also be required to observe a 500-m Monitoring Zone and record the
presence of all marine mammals within this zone. In addition, any
marine mammals observed within 141 m of the active HRG equipment
operating at or below 180 kHz would be documented by PSOs as taken by
Level B harassment. The zones described above would be based upon the
radial distance from the active equipment (rather than being based on
distance from the vessel itself).
Visual Monitoring
A minimum of one NMFS-approved PSO 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
[[Page 31877]]
to and during nighttime ramp-ups of HRG equipment. Visual monitoring
would begin no less than 30 minutes prior to ramp-up of HRG equipment
and would continue until 30 minutes after use of the acoustic source
ceases or until 30 minutes past sunset. PSOs would establish and
monitor the applicable EZs, Buffer Zone and Monitoring Zone as
described above. Visual PSOs would coordinate to ensure 360[deg] visual
coverage around the vessel from the most appropriate observation posts,
and would conduct visual observations using binoculars and the naked
eye while free from distractions and in a consistent, systematic, and
diligent manner. PSOs would estimate distances to marine mammals
located in proximity to the vessel and/or relevant using range finders.
It would be the responsibility of the Lead PSO on duty to communicate
the presence of marine mammals as well as to communicate and enforce
the action(s) that are necessary to ensure mitigation and monitoring
requirements are implemented as appropriate. Position data would be
recorded using hand-held or vessel global positioning system (GPS)
units for each confirmed marine mammal sighting.
Pre-Clearance of the Exclusion Zones
Prior to initiating HRG survey activities, Mayflower would
implement a 30-minute pre-clearance period. During pre-clearance
monitoring (i.e., before ramp-up of HRG equipment begins), the Buffer
Zone would also act as an extension of the 100-m EZ in that
observations of marine mammals within the 200-m Buffer Zone would also
preclude HRG operations from beginning. During this period, PSOs would
ensure that no marine mammals are observed within 200 m of the survey
equipment (500 m in the case of North Atlantic right whales). HRG
equipment would not start up until this 200-m zone (or, 500-m zone in
the case of North Atlantic right whales) is clear of marine mammals for
at least 30 minutes. The vessel operator would notify a designated PSO
of the proposed start of HRG survey equipment as agreed upon with the
lead PSO; the notification time should not be less than 30 minutes
prior to the planned initiation of HRG equipment order to allow the
PSOs time to monitor the EZs and Buffer Zone for the 30 minutes of pre-
clearance. A PSO conducting pre-clearance observations would be
notified again immediately prior to initiating active HRG sources.
If a marine mammal were observed within the relevant EZs or Buffer
Zone during the pre-clearance period, initiation of HRG survey
equipment would not begin until the animal(s) has been observed exiting
the respective EZ or Buffer Zone, or, until an additional time period
has elapsed with no further sighting (i.e., minimum 15 minutes for
small odontocetes and seals, and 30 minutes for all other species). The
pre-clearance requirement would include small delphinoids that approach
the vessel (e.g., bow ride). PSOs would also continue to monitor the
zone for 30 minutes after survey equipment is shut down or survey
activity has concluded.
Ramp-Up of Survey Equipment
When technically feasible, a ramp-up procedure would be used for
geophysical survey equipment capable of adjusting energy levels at the
start or re-start of survey activities. The ramp-up procedure would be
used at the beginning of HRG survey activities in order to provide
additional protection to marine mammals near the Project Area by
allowing them to detect the presence of the survey and vacate the area
prior to the commencement of survey equipment operation at full power.
Ramp-up of the survey equipment would not begin until the relevant EZs
and Buffer Zone has been cleared by the PSOs, as described above. HRG
equipment would be initiated at their lowest power output and would be
incrementally increased to full power. If any marine mammals are
detected within the EZs or Buffer Zone prior to or during ramp-up, the
HRG equipment would be shut down (as described below).
Shutdown Procedures
If an HRG source is active and a marine mammal is observed within
or entering a relevant EZ (as described above) an immediate shutdown of
the HRG survey equipment would be required. When shutdown is called for
by a PSO, the acoustic source would be immediately deactivated and any
dispute resolved only following deactivation. Any PSO on duty would
have the authority to delay the start of survey operations or to call
for shutdown of the acoustic source if a marine mammal is detected
within the applicable EZ. The vessel operator would establish and
maintain clear lines of communication directly between PSOs on duty and
crew controlling the HRG source(s) to ensure that shutdown commands are
conveyed swiftly while allowing PSOs to maintain watch. Subsequent
restart of the HRG equipment would only occur after the marine mammal
has either been observed exiting the relevant EZ, or, until an
additional time period has elapsed with no further sighting of the
animal within the relevant EZ (i.e., 15 minutes for small odontocetes
and seals, and 30 minutes for large whales).
Upon implementation of shutdown, the HRG source may be reactivated
after the marine mammal that triggered the shutdown has been observed
exiting the applicable EZ (i.e., the animal is not required to fully
exit the Buffer Zone where applicable) or, following a clearance period
of 15 minutes for small odontocetes and seals and 30 minutes for all
other species with no further observation of the marine mammal(s)
within the relevant EZ. If the HRG equipment shuts down for brief
periods (i.e., less than 30 minutes) for reasons other than mitigation
(e.g., mechanical or electronic failure) the equipment may be re-
activated as soon as is practicable at full operational level, without
30 minutes of pre-clearance, only if PSOs have maintained constant
visual observation during the shutdown and no visual detections of
marine mammals occurred within the applicable EZs and Buffer Zone
during that time. For a shutdown of 30 minutes or longer, or if visual
observation was not continued diligently during the pause, pre-
clearance observation is required, as described above.
The shutdown requirement would be waived for certain genera of
small delphinids (i.e., Delphinus, Lagenorhynchus, and Tursiops) under
certain circumstances. If a delphinid(s) from these genera is visually
detected approaching the vessel (i.e., to bow ride) or towed survey
equipment, shutdown would not be required. If there is uncertainty
regarding identification of a marine mammal species (i.e., whether the
observed marine mammal(s) belongs to one of the delphinid genera for
which shutdown is waived), PSOs would use best professional judgment in
making the decision to call for a shutdown.
If a species for which authorization has not been granted, or, a
species for which authorization has been granted but the authorized
number of takes have been met, approaches or is observed within the
area encompassing the Level B harassment isopleth (141 m), shutdown
would occur.
Vessel Strike Avoidance
Vessel strike avoidance measures would include, but would not be
limited to, the following, except under circumstances when complying
with these requirements would put the safety of the vessel or crew at
risk:
All vessel operators and crew will maintain vigilant watch
for cetaceans and pinnipeds, and slow down or stop their vessel to
avoid striking these protected species;
[[Page 31878]]
All survey vessels, regardless of size, must observe a 10-
knot speed restriction in DMAs designated by NMFS for the protection of
North Atlantic right whales from vessel strikes. Note that this
requirement includes vessels, regardless of size, to adhere to a 10
knot speed limit in DMAs, not just vessels 65 ft or greater in length;
All vessel operators will reduce vessel speed to 10 knots
(18.5 km/hr) or less when any large whale, any mother/calf pairs, large
assemblages of non-delphinoid cetaceans are observed near (within 100 m
(330 ft)) an underway vessel;
All vessels will maintain a separation distance of 500 m
(1,640 ft) or greater from any sighted North Atlantic right whale;
If underway, vessels must steer a course away from any
sighted North Atlantic right whale at 10 knots (18.5 km/hr) or less
until the 500-m (1,640 ft) minimum separation distance has been
established. If a North Atlantic right whale is sighted in a vessel's
path, or within 100 m (330 ft) to an underway vessel, the underway
vessel must reduce speed and shift the engine to neutral. Engines will
not be engaged until the North Atlantic right whale has moved outside
of the vessel's path and beyond 100 m. If stationary, the vessel must
not engage engines until the North Atlantic right whale has moved
beyond 100 m;
All vessels will maintain a separation distance of 100 m
(330 ft) or greater from any sighted non-delphinoid cetacean. If
sighted, the vessel underway must reduce speed and shift the engine to
neutral, and must not engage the engines until the non-delphinoid
cetacean has moved outside of the vessel's path and beyond 100 m. If a
survey vessel is stationary, the vessel will not engage engines until
the non-delphinoid cetacean has moved out of the vessel's path and
beyond 100 m;
All vessels will maintain a separation distance of 50 m
(164 ft) or greater from any sighted delphinoid cetacean. Any vessel
underway remain parallel to a sighted delphinoid cetacean's course
whenever possible, and avoid excessive speed or abrupt changes in
direction. Any vessel underway reduces vessel speed to 10 knots (18.5
km/hr) or less when pods (including mother/calf pairs) or large
assemblages of delphinoid cetaceans are observed. Vessels may not
adjust course and speed until the delphinoid cetaceans have moved
beyond 50 m and/or the abeam of the underway vessel;
All vessels will maintain a separation distance of 50 m
(164 ft) or greater from any sighted pinniped; and
All vessels underway will not divert or alter course in
order to approach any whale, delphinoid cetacean, or pinniped. Any
vessel underway will avoid excessive speed or abrupt changes in
direction to avoid injury to the sighted cetacean or pinniped.
Project-specific training will be conducted for all vessel crew
prior to the start of survey activities. Confirmation of the training
and understanding of the requirements will be documented on a training
course log sheet. Signing the log sheet will certify that the crew
members understand and will comply with the necessary requirements
throughout the survey activities.
Passive Acoustic Monitoring
Vineyard Wind would also employ passive acoustic monitoring (PAM)
to support monitoring during night time operations to provide for
acquisition of species detections at night. While PAM is not typically
required by NMFS for HRG surveys, it may a provide additional benefit
as a mitigation and monitoring measure to further limit potential
exposure to underwater sound at levels that could result in injury or
behavioral harassment.
Based on our evaluation of the applicant's proposed measures, as
well as other measures considered by NMFS, NMFS has preliminarily
determined that the proposed mitigation measures provide the means
effecting the least practicable impact on the affected species or
stocks and their habitat, paying particular attention to rookeries,
mating grounds, and areas of similar significance.
Proposed 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 such taking. The MMPA implementing
regulations at 50 CFR 216.104 (a)(13) indicate that requests for
authorizations must include the suggested means of accomplishing the
necessary monitoring and reporting that will result in increased
knowledge of the species and of the level of taking or impacts on
populations of marine mammals that are expected to be present in the
proposed action area. 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 or stocks in the area
in which take is anticipated (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 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 other important physical components of
marine mammal habitat); and
Mitigation and monitoring effectiveness.
Proposed Monitoring Measures
As described above, visual monitoring would be performed by
qualified and NMFS-approved PSOs. Mayflower would use independent,
dedicated, trained PSOs, meaning that the PSOs must be employed by a
third-party observer provider, must have no tasks other than to conduct
observational effort, collect data, and communicate with and instruct
relevant vessel crew with regard to the presence of marine mammals and
mitigation requirements (including brief alerts regarding maritime
hazards), and must have successfully completed an approved PSO training
course appropriate for their designated task. Mayflower would provide
resumes of all proposed PSOs (including alternates) to NMFS for review
and approval prior to the start of survey operations.
During survey operations (e.g., any day on which use of an HRG
source is planned to occur), a minimum of one PSO must be on duty and
conducting visual observations at all times on all active survey
vessels during daylight
[[Page 31879]]
hours (i.e., from 30 minutes prior to sunrise through 30 minutes
following sunset) and nighttime ramp-ups of HRG equipment. Visual
monitoring would begin no less than 30 minutes prior to initiation of
HRG survey equipment and would continue until one hour after use of the
acoustic source ceases or until 30 minutes past sunset. PSOs would
coordinate to ensure 360[deg] visual coverage around the vessel from
the most appropriate observation posts, and would conduct visual
observations using binoculars and the naked eye while free from
distractions and in a consistent, systematic, and diligent manner. PSOs
may be on watch for a maximum of four consecutive hours followed by a
break of at least two hours between watches and may conduct a maximum
of 12 hours of observation per 24-hour period. In cases where multiple
vessels are surveying concurrently, any observations of marine mammals
would be communicated to PSOs on all survey vessels.
PSOs would be equipped with binoculars and have the ability to
estimate distances to marine mammals located in proximity to the vessel
and/or exclusion zone using range finders. Reticulated binoculars will
also be available to PSOs for use as appropriate based on conditions
and visibility to support the monitoring of marine mammals. Position
data would be recorded using hand-held or vessel GPS units for each
sighting. Observations would take place from the highest available
vantage point on the survey vessel. General 360-degree scanning would
occur during the monitoring periods, and target scanning by the PSO
would occur when alerted of a marine mammal presence.
During good conditions (e.g., daylight hours; Beaufort sea state
(BSS) 3 or less), to the maximum extent practicable, PSOs would conduct
observations when the acoustic source is not operating for comparison
of sighting rates and behavior with and without use of the acoustic
source and between acquisition periods. Any observations of marine
mammals by crew members aboard any vessel associated with the survey
would be relayed to the PSO team.
Data on all PSO observations would be recorded based on standard
PSO collection requirements. This would include dates, times, and
locations of survey operations; dates and times of observations,
location and weather; details of marine mammal sightings (e.g.,
species, numbers, behavior); and details of any observed marine mammal
take that occurs (e.g., noted behavioral disturbances).
Proposed Reporting Measures
Within 90 days after completion of survey activities, a final
technical report will be provided to NMFS that fully documents the
methods and monitoring protocols, summarizes the data recorded during
monitoring, summarizes the number of marine mammals estimated to have
been taken during survey activities (by species, when known),
summarizes the mitigation actions taken during surveys (including what
type of mitigation and the species and number of animals that prompted
the mitigation action, when known), and provides an interpretation of
the results and effectiveness of all mitigation and monitoring. Any
recommendations made by NMFS must be addressed in the final report
prior to acceptance by NMFS.
In addition to the final technical report, Mayflower will provide
the reports described below as necessary during survey activities. In
the unanticipated event that Mayflower's activities lead to an injury
(Level A harassment) of a marine mammal, Mayflower would immediately
cease the specified activities and report the incident to the NMFS
Office of Protected Resources Permits and Conservation Division and the
NMFS Northeast Regional Stranding Coordinator. The report would include
the following information:
Time, date, and location (latitude/longitude) of the
incident;
Name and type of vessel involved;
Vessel's speed during and leading up to the incident;
Description of the incident;
Status of all sound source use in the 24 hours preceding
the incident;
Water depth;
Environmental conditions (e.g., wind speed and direction,
Beaufort sea state, cloud cover, and visibility);
Description of all marine mammal observations in the 24
hours preceding the incident;
Species identification or description of the animal(s)
involved;
Fate of the animal(s); and
Photographs or video footage of the animal(s) (if
equipment is available).
Activities would not resume until NMFS is able to review the
circumstances of the event. NMFS would work with Mayflower to minimize
reoccurrence of such an event in the future. Mayflower would not resume
activities until notified by NMFS.
In the event that Mayflower personnel discover an injured or dead
marine mammal, Mayflower would report the incident to the OPR Permits
and Conservation Division and the NMFS Northeast Regional Stranding
Coordinator as soon as feasible. The report would 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.
In the unanticipated event of a ship strike of a marine mammal by
any vessel involved in the activities covered by the IHA, Mayflower
would report the incident to the NMFS OPR Permits and Conservation
Division and the NMFS Northeast Regional Stranding Coordinator as soon
as feasible. The report would 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).
[[Page 31880]]
Negligible Impact Analysis and Determination
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 an impact determination. In addition to
considering estimates of the number of marine mammals that might be
``taken'' through harassment, NMFS considers other factors, such as the
likely nature of any responses (e.g., intensity, duration), the context
of any responses (e.g., critical reproductive time or location,
migration), as well as effects on habitat, and the likely effectiveness
of the 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 this
analysis 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, or
ambient noise levels).
To avoid repetition, our analysis applies to all the species listed
in Table 3, given that NMFS expects the anticipated effects of the
proposed survey to be similar in nature. NMFS does not anticipate that
serious injury or mortality would result from HRG surveys, even in the
absence of mitigation, and no serious injury or mortality is
authorized. As discussed in the Potential Effects section, non-auditory
physical effects and vessel strike are not expected to occur. We expect
that potential takes would be in the form of short-term Level B
behavioral harassment in the form of temporary avoidance of the area or
decreased foraging (if such activity were occurring), reactions that
are considered to be of low severity and with no lasting biological
consequences (e.g., Southall et al., 2007). As described above, Level A
harassment is not expected to result given the nature of the
operations, the anticipated size of the Level A harassment zones, the
density of marine mammals in the area, and the required shutdown zones.
Effects on individuals that are taken by Level B harassment, on the
basis of reports in the literature as well as monitoring from other
similar activities, will likely be limited to reactions such as
increased swimming speeds, increased surfacing time, or decreased
foraging (if such activity were occurring). Most likely, individuals
will simply move away from the sound source and temporarily avoid the
area where the survey is occurring. We expect that any avoidance of the
survey area by marine mammals would be temporary in nature and that any
marine mammals that avoid the survey area during the survey activities
would not be permanently displaced. Even repeated Level B harassment of
some small subset of an overall stock is unlikely to result in any
significant realized decrease in viability for the affected
individuals, and thus would not result in any adverse impact to the
stock as a whole.
Regarding impacts to marine mammal habitat, prey species are
mobile, and are broadly distributed throughout the Project Area and the
footprint of the activity is small; therefore, marine mammals that may
be temporarily displaced during survey activities are expected to be
able to resume foraging once they have moved away from areas with
disturbing levels of underwater noise. Because of the availability of
similar habitat and resources in the surrounding area the impacts to
marine mammals and the food sources that they utilize are not expected
to cause significant or long-term consequences for individual marine
mammals or their populations. The HRG survey equipment itself will not
result in physical habitat disturbance. Avoidance of the area around
the HRG survey activities by marine mammal prey species is possible.
However, any avoidance by prey species would be expected to be short
term and temporary.
ESA-listed species for which takes are authorized are North
Atlantic right, fin, sei, and sperm whales, and these effects are
anticipated to be limited to lower level behavioral effects. The
proposed survey is not anticipated to affect the fitness or
reproductive success of individual animals. Since impacts to individual
survivorship and fecundity are unlikely, the proposed survey is not
expected to result in population-level effects for any ESA-listed
species or alter current population trends of any ESA-listed species.
The status of the North Atlantic right whale population is of
heightened concern and, therefore, merits additional analysis. NMFS has
rigorously assessed potential impacts to right whales from this survey.
We have established a 500-m shutdown zone for right whales which is
precautionary considering the Level B harassment isopleth for the
largest source utilized (i.e., GeoMarine Geo-Source 400 tip sparker) is
estimated to be 141 m.
The proposed Project Area encompasses or is in close proximity to
feeding BIAs for right whales (February-April), humpback whales (March-
December), fin whales (March-October), and sei whales (May-November) as
well as a migratory BIA for right whales (March-April and November-
December. Most of these feeding BIAs are extensive and sufficiently
large (705 km\2\ and 3,149 km\2\ for right whales; 47,701 km\2\ for
humpback whales; 2,933 km\2\ for fin whales; and 56,609 km\2\ for sei
whales), and the acoustic footprint of the proposed survey is
sufficiently small, that feeding opportunities for these whales would
not be reduced appreciably. Any whales temporarily displaced from the
proposed Project Area would be expected to have sufficient remaining
feeding habitat available to them, and would not be prevented from
feeding in other areas within the biologically important feeding
habitat. In addition, any displacement of whales from the BIA or
interruption of foraging bouts would be expected to be temporary in
nature. Therefore, we do not expect impacts to whales within feeding
BIAs to to effect the fitness of any large whales.
A migratory BIA for North Atlantic right whales (effective March-
April and November-December) extends from Massachusetts to Florida
(LaBrecque, et al., 2015). Off the south coast of Massachusetts and
Rhode Island, this BIA extends from the coast to beyond the shelf
break. The fact that the spatial acoustic footprint of the proposed
survey is very small relative to the spatial extent of the available
migratory habitat means that right whale migration is not expected to
be impacted by the proposed survey. Required vessel strike avoidance
measures will also decrease risk of ship strike during migration. NMFS
is expanding the standard avoidance measures by requiring that all
vessels, regardless of size, adhere to a 10 knot speed limit in any
established DMAs. Additionally, limited take by Level B harassment of
North Atlantic right whales has been proposed as HRG survey operations
are required to shut down at 500 m to minimize the potential for
behavioral harassment of this species.
[[Page 31881]]
As noted previously, there are several active UMEs occurring in the
vicinity of Mayflower's proposed surveys. Elevated humpback whale
mortalities have occurred along the Atlantic coast from Maine through
Florida since January 2016. Of the cases examined, approximately half
had evidence of human interaction (ship strike or entanglement). 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 stable. Beginning in 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. This event does not provide cause for concern regarding
population level impacts, as the likely population abundance is greater
than 20,000 whales. Elevated North Atlantic right whale mortalities
began in June 2017, primarily in Canada. Overall, preliminary findings
support human interactions, specifically vessel strikes or rope
entanglements, as the cause of death for the majority of the right
whales. Elevated numbers of harbor seal and gray seal mortalities were
first observed in July 2018 and have occurred across Maine, New
Hampshire and Massachusetts. Based on tests conducted so far, the main
pathogen found in the seals is phocine distemper virus although
additional testing to identify other factors that may be involved in
this UME are underway. The UME does not yet provide cause for concern
regarding population-level impacts to any of these stocks. For harbor
seals, the population abundance is over 75,000 and annual M/SI (345) is
well below PBR (2,006) (Hayes et al., 2018). For gray seals, the
population abundance in the United States is over 27,000, with an
estimated abundance including seals in Canada of approximately 505,000,
and abundance is likely increasing in the U.S. Atlantic EEZ as well as
in Canada (Hayes et al., 2018).
Direct physical interactions (ship strikes and entanglements)
appear to be responsible for many of the UME humpback and right whale
mortalities recorded. The proposed HRG survey will require ship strike
avoidance measures which would minimize the risk of ship strikes while
fishing gear and in-water lines will not be employed as part of the
survey. Furthermore, the proposed activities are not expected to
promote the transmission of infectious disease among marine mammals.
The survey is not expected to result in the deaths of any marine
mammals or combine with the effects of the ongoing UMEs to result in
any additional impacts not analyzed here. Accordingly, Mayflower did
not request, and NMFS is not proposing to authorize, take of marine
mammals by serious injury, or mortality.
The required mitigation measures are expected to reduce the number
and/or severity of takes by giving animals the opportunity to move away
from the sound source before HRG survey equipment reaches full energy
and preventing animals from being exposed to sound levels that have the
potential to cause injury (Level A harassment) and more severe Level B
harassment during HRG survey activities, even in the biologically
important areas described above. No Level A harassment is anticipated
or authorized.
NMFS expects that takes would be in the form of short-term Level B
behavioral harassment in the form of brief startling reaction and/or
temporary vacating of the area, or decreased foraging (if such activity
were occurring)--reactions that (at the scale and intensity anticipated
here) are considered to be of low severity and with no lasting
biological consequences. Since both the source and the marine mammals
are mobile, only a smaller area would be ensonified by sound levels
that could result in take for only a short period. Additionally,
required mitigation measures would reduce exposure to sound that could
result in more severe behavioral harassment.
In summary and as described above, the following factors primarily
support our preliminary determination that the impacts resulting from
this activity are not expected to adversely affect the species or stock
through effects on annual rates of recruitment or survival:
No mortality or serious injury is anticipated or proposed
to be authorized;
No Level A harassment (PTS) is anticipated;
Any foraging interruptions are expected to be short term
and unlikely to be cause significantly impacts;
Impacts on marine mammal habitat and species that serve as
prey species for marine mammals are expected to be minimal and the
alternate areas of similar habitat value for marine mammals are readily
available;
Take is anticipated to be primarily Level B behavioral
harassment consisting of brief startling reactions and/or temporary
avoidance of the Project Area;
Survey activities would occur in such a comparatively
small portion of the biologically important area for north Atlantic
right whale migration, that any avoidance of the Project Area due to
activities would not affect migration. In addition, mitigation measures
to shut down at 500 m to minimize potential for Level B behavioral
harassment would limit both the number and severity of take of the
species;
Similarly, due to the relatively small footprint of the
survey activities in relation to the size of a biologically important
areas for right, humpback, fin, and sei whales foraging, the survey
activities would not affect foraging success of this species; and
Proposed mitigation measures, including visual monitoring
and shutdowns, are expected to minimize the intensity of potential
impacts to marine mammals.
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 proposed monitoring and
mitigation measures, NMFS preliminarily finds that the total marine
mammal take from the Mayflower's proposed HRG surveys will have a
negligible impact on all affected marine mammal species or stocks.
Small Numbers
As noted above, only small numbers of incidental take may be
authorized under Sections 101(a)(5)(A) and (D) of the MMPA for
specified activities other than military readiness activities. The MMPA
does not define small numbers and so, in practice, where estimated
numbers are available, NMFS compares the number of individuals taken to
the most appropriate estimation of abundance of the relevant species or
stock in our determination of whether an authorization is limited to
small numbers of marine mammals. Additionally, other qualitative
factors may be considered in the analysis, such as the temporal or
spatial scale of the activities.
The numbers of marine mammals that we authorize to be taken, for
all species and stocks, would be considered small relative to the
relevant stocks or populations (less than one third of the best
available population abundance for all species and stocks) (see Table
9). In fact, the total amount of taking proposed for authorization for
all species is 1 percent or less for all affected stocks.
Based on the analysis contained herein of the proposed activity
(including the proposed mitigation and monitoring measures) and the
[[Page 31882]]
anticipated take of marine mammals, NMFS preliminarily finds that small
numbers of marine mammals will be taken relative to the population size
of the affected species or stocks.
Unmitigable Adverse Impact Analysis and Determination
There are no relevant subsistence uses of the affected marine
mammal stocks or species implicated by this action. Therefore, NMFS has
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.
Endangered Species Act (ESA)
Section 7(a)(2) of the Endangered Species Act of 1973 (16 U.S.C.
1531 et seq.) requires that each Federal agency insure that any action
it authorizes, funds, or carries out is not likely to jeopardize the
continued existence of any endangered or threatened species or result
in the destruction or adverse modification of designated critical
habitat. To ensure ESA compliance for the issuance of IHAs, NMFS
consults internally, in this case with the NMFS Greater Atlantic
Regional Fisheries Office (GARFO), whenever we propose to authorize
take for endangered or threatened species.
The NMFS Office of Protected Resources Permits and Conservation
Division is proposing to authorize the incidental take of four species
of marine mammals listed under the ESA: The North Atlantic right, fin,
sei, and sperm whale. The Permits and Conservation Division has
requested initiation of Section 7 consultation with NMFS GARFO for the
issuance of this IHA. NMFS will conclude the ESA section 7 consultation
prior to reaching a determination regarding the proposed issuance of
the authorization.
Proposed Authorization
As a result of these preliminary determinations, NMFS proposes to
issue an IHA to Mayflower for conducting marine site characterization
surveys offshore of Massachusetts in the area of the Commercial Lease
of Submerged Lands for Renewable Energy Development on the Outer
Continental Shelf (OCS-A 0521) and along a potential submarine cable
route to landfall at Falmouth, Massachusetts for a period of one year
from the date of issuance, provided the previously mentioned
mitigation, monitoring, and reporting requirements are incorporated. A
draft of the proposed IHA can be found at https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act.
Request for Public Comments
We request comment on our analyses, the proposed authorization, and
any other aspect of this Notice of Proposed IHA for the proposed HRG
survey. We also request at this time comment on the potential Renewal
of this proposed IHA as described in the paragraph below. Please
include with your comments any supporting data or literature citations
to help inform decisions on the request for this IHA or a subsequent
Renewal IHA.
On a case-by-case basis, NMFS may issue a one-year Renewal IHA
following notice to the public providing an additional 15 days for
public comments when (1) up to another year of identical or nearly
identical, or nearly identical, activities as described in the
Specified Activities section of this notice is planned or (2) the
activities as described in the Specified Activities section of this
notice would not be completed by the time the IHA expires and a Renewal
would allow for completion of the activities beyond that described in
the Dates and Duration section of this notice, provided all of the
following conditions are met:
A request for renewal is received no later than 60 days
prior to the needed Renewal IHA effective date (recognizing that the
Renewal IHA expiration date cannot extend beyond one year from
expiration of the initial IHA);
The request for renewal must include the following:
(1) An explanation that the activities to be conducted under the
requested Renewal IHA are identical to the activities analyzed under
the initial IHA, are a subset of the activities, or include changes so
minor (e.g., reduction in pile size) that the changes do not affect the
previous analyses, mitigation and monitoring requirements, or take
estimates (with the exception of reducing the type or amount of take);
and
(2) A preliminary monitoring report showing the results of the
required monitoring to date and an explanation showing that the
monitoring results do not indicate impacts of a scale or nature not
previously analyzed or authorized; and
Upon review of the request for Renewal, the status of the
affected species or stocks, and any other pertinent information, NMFS
determines that there are no more than minor changes in the activities,
the mitigation and monitoring measures will remain the same and
appropriate, and the findings in the initial IHA remain valid.
Dated: May 19, 2020.
Donna S. Wieting,
Director, Office of Protected Resources, National Marine Fisheries
Service.
[FR Doc. 2020-11203 Filed 5-26-20; 8:45 am]
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