Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to Ferry Berth Improvements in Tongass Narrows in Ketchikan, Alaska, 15387-15408 [2022-05561]
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Dated: March 11, 2022.
Carrie Diane Robinson,
Director, Office of Habitat Conservation,
National Marine Fisheries Service.
[FR Doc. 2022–05553 Filed 3–17–22; 8:45 am]
BILLING CODE 3510–22–P
[RTID 0648–XB799]
Takes of Marine Mammals Incidental to
Specified Activities; Taking Marine
Mammals Incidental to Ferry Berth
Improvements in Tongass Narrows in
Ketchikan, Alaska
National Marine Fisheries
Service (NMFS), National Oceanic and
Atmospheric Administration (NOAA),
Commerce.
ACTION: Notice; issuance of an incidental
harassment authorization.
AGENCY:
In accordance with the
regulations implementing the Marine
Mammal Protection Act (MMPA) as
amended, notification is hereby given
that NMFS has issued an incidental
harassment authorization (IHA) to the
Alaska Department of Transportation
and Public Facilities (ADOT) to
incidentally harass, by Level A
harassment and Level B harassment
only, marine mammals during
construction activities associated with
construction of four ferry berth facilities
in Tongass Narrows in Ketchikan,
Alaska.
SUMMARY:
This authorization is effective
from March 5, 2022 through March 4,
2023.
DATES:
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15387
FOR FURTHER INFORMATION CONTACT:
Leah Davis, 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,
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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
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‘‘mitigation’’); and requirements
pertaining to the mitigation, monitoring
and reporting of the takings are set forth.
The definitions of all applicable MMPA
statutory terms cited above are included
in the relevant sections below.
Summary of Request
On August 19, 2021, NMFS received
a request from the ADOT for an IHA to
take marine mammals incidental to the
construction of two ferry berth facilities
in Tongass Narrows in Ketchikan,
Alaska: The Gravina Airport Ferry
Layup Facility and the Gravina Freight
Facility. On December 17, 2021 we
received a revised request that included
additional work components associated
with the Revilla New Ferry Berth and
Upland Improvements and the New
Gravina Island Shuttle Ferry Berth and
Related Terminal Improvements in the
same region. The application was
deemed adequate and complete on
January 4, 2022. ADOT’s request is for
take of a small number of eight species
of marine mammals, by Level B
harassment and Level A harassment. Of
those eight species, five (Steller sea lion
(Eumetopias jubatus), harbor seal
(Phoca vitulina richardii), harbor
porpoise (Phocoena phocoena), Dall’s
porpoise (Phocoenoides dalli) and
minke whale (Balaenoptera
acutorostrata)) may also be taken by
Level A harassment. Neither ADOT nor
NMFS expects serious injury or
mortality to result from this activity
and, therefore, an IHA is appropriate.
NMFS previously issued two
consecutive IHAs and a Renewal IHA to
ADOT for this work (85 FR 673, January
7, 2020; 86 FR 23938, May 05, 2021).
ADOT complied with all the
requirements (e.g., mitigation,
monitoring, and reporting) of the
previous IHAs and information
regarding their monitoring results may
be found in the Description of Marine
Mammals in the Area of Specified
Activities and Marine Mammal
Occurrence and Take Calculation and
Estimation sections. An IHA for the first
phase of construction of the KetchikanGravina Access Project was issued to
ADOT on December 20, 2019 (85 FR
673, January 7, 2020). Complete
construction of two of those
components, the Revilla New Ferry
Berth and Upland Improvements and
Gravina Island Shuttle Ferry Berth
Facility/Related Terminal
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Improvements, did not occur within the
timeframe authorized by the Phase 1
IHA and will not be finished before the
expiration of the subsequent one-year
renewal (86 FR 23938, May 05, 2021).
Therefore, ADOT requested a new IHA
for incidental take associated with the
continued marine construction of these
facilities.
Description of the Specified Activity
ADOT is making improvements to
existing ferry berths and constructing
new ferry berths on Gravina Island and
Revillagigedo (Revilla) Island in
Tongass Narrows, near Ketchikan in
southeast Alaska (Figure 1 of proposed
IHA; 87 FR 5980; February 2, 2022).
These ferry facilities provide the only
public access between the city of
Ketchikan, AK on Revilla Island, and
the Ketchikan International Airport on
Gravina Island. The project’s planned
activities that have the potential to take
marine mammals, by Level A
harassment and Level B harassment,
include vibratory and impact pile
driving, down-the-hole (DTH)
operations for pile installation (rock
socketing of piles and tension anchors
to secure piles), and vibratory pile
removal. The marine construction
associated with the activities is planned
to occur over 91 non-consecutive days
over one year beginning March 2022.
A detailed description of the planned
construction project is provided in the
Federal Register notice for the proposed
IHA (87 FR 5980; February 2, 2022).
Since that time, no changes have been
made to the planned activities.
Therefore, a detailed description is not
provided here. Please refer to that
Federal Register notice for the
description of the specific activity.
Comments and Responses
A notice of NMFS’ proposal to issue
an IHA to ADOT was published in the
Federal Register on February 2, 2022
(87 FR 5980). That notice described, in
detail, ADOT’s activity, the marine
mammal species that may be affected by
the activity, and the anticipated effects
on marine mammals. During the 30-day
public comment period, NMFS did not
receive any public comments.
Description of Marine Mammals in the
Area of Specified Activities
Sections 3 and 4 of the application
summarize available information
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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’ Stock
Assessment Reports (SARs; https://
www.fisheries.noaa .gov/national/
marine-mammal-protection/marinemammal-stock-assessments) and more
general information about these species
(e.g., physical and behavioral
descriptions) may be found on NMFS’
website (https://www.fisheries.noaa
.gov/find-species).
Table 1 lists all species or stocks for
which take is expected and proposed to
be authorized for this specified activity,
and summarizes information related to
the population or stock, including
regulatory status under the MMPA and
Endangered Species Act (ESA) and
potential biological removal (PBR),
where known. For taxonomy, we follow
Committee on Taxonomy (2021). 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’ 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’ 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’ U.S. Alaska SARs (e.g., Muto et
al. 2021). All values presented in Table
1 are the most recent available at the
time of publication and are available in
the draft 2021 SARs (Muto et al. 2021;
available online at: https://
www.fisheries.noaa.gov/national/
marine-mammal-protection/draftmarine-mammal-stock-assessmentreports).
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TABLE 1—MARINE MAMMAL SPECIES OR STOCKS FOR WHICH TAKE IS EXPECTED AND AUTHORIZED
Common name
Scientific name
ESA/
MMPA
status;
strategic
(Y/N) 1
MMPA stock
Stock
abundance
Nbest,
(CV; Nmin; most recent
abundance survey) 2
PBR
Annual
M/SI 3
Order Cetartiodactyla—Cetacea—Superfamily Mysticeti (baleen whales)
Family Balaenidae:
Humpback whale ................
Minke whale ........................
Megaptera novaeangliae ..........
Balaenoptera acutorostrata ......
Central North Pacific .................
Alaska .......................................
E, D, Y
-, N
10,103 (0.3; 7,890; 2006)
N.A. (See SAR; N.A.;
see SAR).
83
UND
26
0
24
3.5
2.2
UND
1
*0.4
0.2
0
See SAR
34
See SAR
37
Order Cetartiodactyla—Cetacea—Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
Family Delphinidae:
Killer whale .........................
Orcinus orca .............................
Pacific white-sided dolphin
Family Phocoenidae:
Harbor porpoise ..................
Lagenorhynchus obliquidens ....
Alaska Resident ........................
West Coast Transient ...............
Northern Resident .....................
North Pacific .............................
-, N
-, N
-, N
-,-; N
2,347 (N.A.; 2,347; 2012)
349 (N.A, 349; 2018) ......
302 (N.A.; 302; 2018 ......
26,880 (N.A.; N.A.; 1990)
Phocoena phocoena .................
Southeast Alaska ......................
-, Y
See SAR (see SAR; see
SAR; 2012).
See SAR (see SAR; see
SAR; 2015).
Dall’s porpoise ....................
Phocoenoides dalli ....................
Alaska .......................................
-, N
Order Carnivora—Superfamily Pinnipedia
Family Otariidae (eared seals
and sea lions):
Steller sea lion ....................
Eumetopias jubatus ..................
Eastern U.S. .............................
-,-, N
43,201 (see SAR;
43,201; 2017).
2,592
112
Family Phocidae (earless seals):
Harbor seal .........................
Phoca vitulina richardii ..............
Clarence Strait ..........................
-, N
27,659 (See SAE;
24,854; 2015).
746
40
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1 Endangered Species Act (ESA) status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-) indicates that the species is not listed under the
ESA or designated as depleted under the MMPA. Under the MMPA, a strategic stock is one for which the level of direct human-caused mortality exceeds PBR or
which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed under the ESA is automatically
designated under the MMPA as depleted and as a strategic stock.
2 NMFS marine mammal stock assessment reports online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments. CV is coefficient of variation; Nmin is the minimum estimate of stock abundance. In some cases, CV is not applicable (N.A.).
3 These values, found in NMFS’ SARs, represent annual levels of human-caused mortality plus serious injury (M/SI) from all sources combined (e.g., commercial
fisheries, ship strike). Annual M/SI often cannot be determined precisely and is in some cases presented as a minimum value or range. A CV associated with estimated mortality due to commercial fisheries is presented in some cases.
All species that could potentially
occur in the project area are included in
Table 3–1 of ADOT’s IHA application.
However, the spatial occurrence of gray
whale and fin whale is such that take is
not expected to occur, and they are not
discussed further beyond the
explanation provided here. Gray whales
have not been reported by any local
experts or recorded in monitoring
reports and it would be extremely
unlikely for a gray whale to enter
Tongass Narrows or the small portions
of Revillagigedo Channel this project
will impact. Similarly for fin whale,
sightings have not been reported and it
would be unlikely for a fin whale to
enter the project area as they are
generally associated with deeper, more
offshore waters. The eight species (with
10 managed stocks) in Table 1
temporally and spatially co-occur with
the activity to the degree that take is
reasonably likely to occur, and we have
authorized it.
A detailed description of the of the
species likely to be affected by ADOT’s
project, including brief introductions to
the species and relevant stocks as well
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as available information regarding
population trends and threats, and
information regarding local occurrence,
were provided in the Federal Register
notice for the proposed IHA (87 FR
5980; February 2, 2022); since that time,
we are not aware of any changes in the
status of these species and stocks;
therefore, detailed descriptions are not
provided here. Please refer to that
Federal Register notice for these
descriptions. Please also refer to NMFS’
website (https://www.fisheries.noaa
.gov/find-species) for generalized
species accounts.
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
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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 2.
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TABLE 2—MARINE MAMMAL HEARING GROUPS
[NMFS, 2018]
Generalized hearing
range *
Hearing group
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.
(2007) on the basis of data indicating
that phocid species have consistently
demonstrated an extended frequency
range of hearing compared to otariids,
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. Eight marine
mammal species (six cetacean and two
pinniped (one otariid and one phocid)
species) have the reasonable potential to
co-occur with the planned activities.
Please refer to Table 1. Of the cetacean
species that may be present, two are
classified as low-frequency cetaceans
(i.e., all mysticete species), two are
classified as mid-frequency cetaceans
(i.e., all delphinid and ziphiid species
and the sperm whale), and two are
classified as high-frequency cetaceans
(i.e., harbor porpoise, Dall’s porpoise
and Kogia spp.).
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Potential Effects of Specified Activities
on Marine Mammals and Their Habitat
The effects of underwater noise from
the ADOT’s activities have the potential
to result in take of marine mammals by
Level B harassment and Level A
harassment in the vicinity of the survey
area. The notice of proposed IHA (87 FR
5980; February 2, 2022) included a
discussion of the effects of
anthropogenic noise on marine
mammals and the potential effects of
underwater noise from ADOT’s
construction activities on marine
mammals and their habitat. That
information and analysis is incorporated
by reference into this final IHA and is
not repeated here; please refer to the
notice of the proposed IHA (87 FR 5980;
February 2, 2022).
The Estimated Take section in this
document includes a quantitative
analysis of the number of individuals
that are expected to be taken by this
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activity. The Negligible Impact Analysis
and Determination section considers the
content of this section, the Estimated
Take section, and the Mitigation
Measures 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. We also provided additional
description of sound sources in our
notice of proposed IHA (87 FR 5980;
February 2, 2022).
Estimated Take
This section provides an estimate of
the number of incidental takes
authorized 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 will primarily be by
Level B harassment, as use of the
acoustic sources (i.e., impact and
vibratory pile driving and DTH) have
the potential to result in disruption of
behavioral patterns for individual
marine mammals. There is also some
potential for auditory injury (Level A
harassment) to result, primarily for
mysticetes, high frequency species and
phocids because predicted auditory
injury zones are larger than for midfrequency species and otariids. Auditory
injury is unlikely to occur to mid-
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frequency species and otariids. The
required mitigation and monitoring
measures are expected to minimize the
severity of such taking to the extent
practicable.
As described previously, no mortality
is anticipated or 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 take
estimate.
Acoustic Thresholds
NMFS recommends the use of
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
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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 harassed in a manner
we consider Level B harassment when
exposed to underwater anthropogenic
noise above received levels of 120 dB re
1 microPascal (mPa) (root mean square
(rms)) for continuous (e.g., vibratory
pile-driving, DTH) and above 160 dB re
1 mPa (rms) for non-explosive impulsive
(e.g., seismic airguns) or intermittent
(e.g., scientific sonar) sources. This take
estimation includes disruption of
behavioral patterns resulting directly in
response to noise exposure (e.g.,
avoidance), as well as that resulting
indirectly from associated impacts such
as TTS or masking. ADOT’s planned
activity includes the use of continuous
(vibratory pile driving/removal and
DTH) and impulsive (impact pile
driving and DTH) sources, and therefore
both the 120 and 160 dB re 1 mPa (rms)
thresholds are 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). ADOT’s planned activity
includes the use of impulsive (impact
pile driving and DTH) and nonimpulsive (vibratory pile driving/
removal and DTH) sources.
These thresholds are provided in
Table 3 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
https://www.fisheries.noaa.gov/
national/marine-mammal-protection/
marine-mammal-acoustic-technicalguidance.
TABLE 3—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) ...........................
Cell
Cell
Cell
Cell
Cell
1:
3:
5:
7:
9:
Lpk,flat:
Lpk,flat:
Lpk,flat:
Lpk,flat:
Lpk,flat:
219
230
202
218
232
dB;
dB;
dB;
dB;
dB;
Non-impulsive
LE,LF,24h: 183 dB ......................
LE,MF,24h: 185 dB ......................
LE,HF,24h: 155 dB ......................
LE,PW,24h: 185 dB .....................
LE,OW,24h: 203 dB .....................
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.
* Dual metric acoustic thresholds for impulsive sounds: Use whichever results in the largest isopleth for calculating PTS onset. If a non-impulsive sound has the potential of exceeding the peak sound pressure level thresholds associated with impulsive sounds, these thresholds should
also be considered.
Note: Peak sound pressure (Lpk) has a reference value of 1 μPa, and cumulative sound exposure level (LE) has a reference value of 1μPa2s.
In this Table, thresholds are abbreviated to reflect American National Standards Institute standards (ANSI 2013). However, peak sound pressure
is defined by ANSI as incorporating frequency weighting, which is not the intent for this Technical Guidance. Hence, the subscript ‘‘flat’’ is being
included to indicate peak sound pressure should be flat weighted or unweighted within the generalized hearing range. The subscript associated
with cumulative sound exposure level thresholds indicates the designated marine mammal auditory weighting function (LF, MF, and HF
cetaceans, and PW and OW pinnipeds) and that the recommended accumulation period is 24 hours. The cumulative sound exposure level
thresholds could be exceeded in a multitude of ways (i.e., varying exposure levels and durations, duty cycle). When possible, it is valuable for
action proponents to indicate the conditions under which these acoustic thresholds will be exceeded.
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Ensonified Area
Here, we describe operational and
environmental parameters of the activity
that will feed into identifying the area
ensonified above the acoustic
thresholds, which include source levels
and transmission loss coefficient.
The sound field in the project area is
the existing background noise plus
additional construction noise from the
project. Marine mammals are expected
to be affected via sound generated by
the primary components of the project
(i.e., impact pile driving, vibratory pile
driving, vibratory pile removal, and
DTH).
In order to calculate distances to the
Level A harassment and Level B
harassment sound thresholds for the
methods and piles being used in this
project, NMFS used acoustic monitoring
data from other locations to develop
source levels for the various pile types,
sizes and methods (Table 4). Note that
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piles of differing sizes have different
sound source levels (SSLs).
Empirical data from recent ADOT
sound source verification (SSV) studies
at Ketchikan were used to estimate SSLs
for vibratory and impact driving of 30inch steel pipe piles (Denes et al. 2016).
Data from Ketchikan was used because
of its proximity to this project in
Tongass Narrows. However, the use of
data from Alaska sites was not
appropriate in all instances. Details are
described below.
For vibratory driving of 24-inch steel
piles, data from a Navy pile driving
project in the Puget Sound, WA was
reviewed (Navy 2015). From this
review, ADOT determined the Navy’s
suggested source value of 161 decibels
(dB) root mean squared (rms) was an
appropriate proxy source value, and
NMFS concurs. Because the source
value of smaller piles of the same
general type (steel in this case) are not
expected to exceed a larger pile, the
same 161 dB rms source value was used
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for 20-inch steel piles. This assumption
conforms with source values presented
in Navy (2015) for a project using 16inch steel piles at Naval Base Kitsap in
Bangor, WA.
ADOT used source values of 177 dB
sound exposure level (SEL) and 190 dB
rms for impact driving of 24-inch and
20-inch steel piles. These values were
determined based on summary values
presented in Caltrans (2015) for impact
driving of 24-inch steel piles. NMFS
concurs that the same source value was
an acceptable proxy for impact driving
of 20-inch steel piles.
Sound pressure levels in the water
column resulting from DTH are not well
studied. Because DTH hole creation
includes both impulsive and continuous
components, NMFS guidance currently
recommends that it be treated as a
continuous sound for Level B
calculations and as an impulsive sound
for Level A calculations (Table 10). In
the absence of data specific to different
hole sizes, current NMFS guidance
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recommends that calculation of Level B
zones for DTH use the same continuous
SSL of 167 dB SEL for all hole sizes
(Heyvaert and Reyff 2021).
Recommended SSLs for 30-inch and 24inch holes as well as 8-inch holes for
tension anchors and micropiles for use
in the calculation of Level A harassment
thresholds are provided by current
NMFS guidance and in Table 4.
TABLE 4—ESTIMATES OF MEAN UNDERWATER SOUND LEVELS GENERATED DURING VIBRATORY AND IMPACT PILE
INSTALLATION, DTH, AND VIBRATORY PILE REMOVAL
Method and pile type
SSL at 10 m
Literature source
Vibratory hammer ...................................
dB rms
30-inch steel piles ..................................
162
Denes et al. 2016.
24-inch steel piles ..................................
161
Navy 2015.
20-inch steel piles ..................................
161
Navy 2015.
DTH of rock sockets and tension anchors.
dB rms
All pile diameters ....................................
167
Heyvaert and Reyff 2021.
DTH of rock sockets and tension anchors.
dB SELss
dB peak
30-inch rock socket ................................
164
194
Reyff and Heyvaert 2019; Reyff 2020;
Denes et al. 2016.
24-inch rock socket ................................
159
184
Heyvaert and Reyff 2021.
8-inch tension anchor/micropile .............
144
170
Reyff 2020.
Impact Hammer
dB rms
dB SEL
dB peak
30-inch steel piles .................................
195
181
209
Denes et al. 2016.
24-inch steel piles .................................
190
177
203
Caltrans 2015.
20-inch steel piles .................................
190
177
202
Caltrans 2015.
Note: It is assumed that noise levels during pile installation and removal are similar. SEL = sound exposure level; dB peak = peak sound level;
rms = root mean square.
Simultaneous use of two impact,
vibratory, or DTH hammers, or any
combination of those equipment, could
occur. Such occurrences are anticipated
to be infrequent, will be for short
durations on any given day, and ADOT
anticipates that no more than two
hammers will be operated concurrently.
Simultaneous use of two hammers or
DTH systems could occur at the same
project site, or at two different, but
nearby project sites. Simultaneous use
of hammers could result in increased
SPLs and harassment zone sizes given
the proximity of the component driving
sites and the physical rules of decibel
addition. ADOT anticipates that
concurrent use of two hammers
producing continuous noise could occur
on 44 days, which is half the anticipated
number of days of construction (91
days) and represents complete overlap
between the two contracts and/or
represents use of two hammers by a
single contractor. Although it is unlikely
that overlap will be complete, ADOT
anticipates, and NMFS concurs, this
scenario represents the potential worst
case scenario, given that a more accurate
estimate is not possible, and concurrent
operation of hammers will be
incidental. Given that the use of more
than one hammer for pile installation on
the same day (whether simultaneous or
not) will increase the number of piles
installed per day, this is anticipated to
result in a reduction of the total number
of days of pile installation. Table 5
shows how potential scenarios would
reduce the total number of pile driving
days and weeks. However, as described
in the Marine Mammal Occurrence and
Take Calculation and Estimation
section below, ADOT has conservatively
calculated take with the assumption that
pile driving will occur on all 91 days.
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TABLE 5—CALCULATED REDUCTION OF PILE DRIVING DAYS BASED ON PERCENTAGE OF PROJECT DAYS WITH TWO
HAMMERS IN USE
0 ...........................................................................................
10 .........................................................................................
20 .........................................................................................
30 .........................................................................................
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Days of work
completed
during overlap
(2 hammers)
Days of
overlap
Percent overlap
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0.0
9.1
18.2
27.3
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Remaining
days of work
with single
hammer
0.0
18.2
36.4
54.6
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91.0
72.8
54.6
36.4
18MRN1
Total number
of days of
work
91.0
81.9
72.8
63.7
Weeks of work
15.2
13.7
12.1
10.6
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TABLE 5—CALCULATED REDUCTION OF PILE DRIVING DAYS BASED ON PERCENTAGE OF PROJECT DAYS WITH TWO
HAMMERS IN USE—Continued
Days of work
completed
during overlap
(2 hammers)
Days of
overlap
Percent overlap
40 .........................................................................................
50 .........................................................................................
36.4
45.5
Remaining
days of work
with single
hammer
72.8
91.0
harassment and Level B harassment
zones.
When two DTH hammers operate
simultaneously their continuous sound
components overlap completely in time.
When the Level B isopleth of one DTH
sound source encompasses the isopleth
of another DTH sound source, the
sources are considered additive and
combined using the following rules
(Table 7). The method described below
was based on one created by
Washington State Department of
Transportation (WSDOT) and has been
updated and modified by NMFS
(WSDOT 2020). For addition of two
simultaneous DTH hammers, the
difference between the two SSLs is
calculated, and if that difference is
between 0 and 1 dB, 3 dB are added to
NMFS (2018b) handles overlapping
sound fields created by the use of more
than one hammer differently for
impulsive (impact hammer and Level A
harassment zones for drilling with a
DTH hammer) and continuous sound
sources (vibratory hammer and Level B
harassment zones for drilling with a
DTH hammer; Table 6) and differently
for impulsive sources with rapid
impulse rates of multiple strikes per
second (DTH) and slow impulse rates
(impact hammering) (NMFS 2021). It is
unlikely that the two impact hammers
will strike at the same instant, and
therefore, the SPLs will not be adjusted
regardless of the distance between
impact hammers. In this case, each
impact hammer will be considered to
have its own independent Level A
Total number
of days of
work
18.2
0.0
Weeks of work
54.6
45.5
9.1
7.6
the higher SSL; if difference is between
2 or 3 dB, 2 dB are added to the highest
SSL; if the difference is between 4 to 9
dB, 1 dB is added to the highest SSL;
and with differences of 10 or more
decibels, there is no addition.
When two continuous noise sources,
such as vibratory hammers, have
overlapping sound fields, there is
potential for higher sound levels than
for non-overlapping sources.
When two or more vibratory hammers
are used simultaneously, and the
isopleth of one sound source
encompasses the isopleth of another
sound source, the sources are
considered additive and source levels
are combined using the rules in Table 6,
similar to that described above for DTH.
TABLE 6—RULES FOR COMBINING SOUND SOURCE LEVELS GENERATED DURING PILE INSTALLATION
Hammer types
Difference in SSL
Level A zones
Vibratory, Impact ...........................................
Impact, Impact ...............................................
Any ........................
Any ........................
Vibratory, Vibratory or DTH, DTH .................
0 or 1 dB ...............
2 or 3 dB ...............
4 to 9 dB ...............
10 dB or more .......
Use impact zones .............................
Use zones for each pile size and
number of strikes.
Add 3 dB to the higher source level
Add 2 dB to the higher source level.
Add 1 dB to the higher source level
Add 0 dB to the higher source level
During pile driving, it is common for
pile installation to start and stop
multiple times as each pile is adjusted
and its progress is measured and
documented, though as stated above, for
short durations, it is anticipated that
multiple hammers could be in use
simultaneously. Following an approach
modified from WSDOT in their
Biological Assessment manual (WSDOT
2020) and described in Table 7, decibel
addition calculations were carried out
Level B zones
Use largest zone.
Use zone for each pile size.
Add
Add
Add
Add
3
2
1
0
dB
dB
dB
dB
to
to
to
to
the
the
the
the
higher
higher
higher
higher
source
source
source
source
level
level.
level.
level.
for possible combinations of pile driving
and DTH throughout the project area.
The source levels included in Table 7
are used to estimate the Level A
harassment zones and the Level B
harassment zones.
TABLE 7—COMBINED SSLS (dB AT 10 m) GENERATED DURING PILE INSTALLATION AND REMOVAL FOR COMBINATIONS OF
TWO PIECES OF EQUIPMENT: IMPACT HAMMER, VIBRATORY HAMMER, AND DOWN-THE-HOLE DRILL
Method
Vibratory (RMS)
Pile diameter
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Vibratory (RMS) ....................
DTH (RMS) ...........................
DTH (SEL) .............................
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20
24
30
8
24
30
8
24
30
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SSL
161
161
162
167
167
167
144
159
164
DTH (RMS)
DTH (SEL)
20
24
30
8
24
30
8
24
30
161
164
164
165
168
168
168
................
................
................
161
164
164
165
168
168
168
................
................
................
162
165
165
165
168
168
168
................
................
................
167
168
168
168
170
170
170
................
................
................
167
168
168
168
170
170
170
................
................
................
167
168
168
168
170
170
170
................
................
................
144
................
................
................
................
................
................
147
159
164
159
................
................
................
................
................
................
159
162
165
164
................
................
................
................
................
................
164
165
167
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No addition is warranted for impact
pile driving in combination with
vibratory or impact pile driving or DTH
(NMFS 2021).
Level B Harassment Zones
Transmission loss (TL) is the decrease
in acoustic intensity as an acoustic
pressure wave propagates out from a
source. TL parameters vary with
frequency, temperature, sea conditions,
current, source and receiver depth,
water depth, water chemistry, and
bottom composition and topography.
The general formula for underwater TL
is:
TL = B * Log10 (R1/R2),
Where:
TL = transmission loss in dB
B = transmission loss coefficient; for practical
spreading equals 15
R1 = the distance of the modeled SPL from
the driven pile, and
R2 = the distance from the driven pile of the
initial measurement
The recommended TL coefficient for
most nearshore environments is the
practical spreading value of 15. This
value results in an expected propagation
environment that will lie between
spherical and cylindrical spreading loss
conditions, which is the most
appropriate assumption for ADOT’s
planned activity in the absence of
specific modelling.
All Level B harassment isopleths are
reported in Table 8 and Table 9 below.
It should be noted that based on the
geography of Tongass Narrows and the
surrounding islands, sound will not
reach the full distance of the Level B
harassment isopleth in most directions.
Generally, due to interaction with land,
only a thin slice of the possible area is
ensonified to the full distance of the
Level B harassment isopleth.
The size of the Level B harassment
zone during concurrent operation of two
vibratory or DTH hammers will depend
on the combination of sound sources
and the decibel addition of two
hammers producing continuous noise.
Table 8 shows the distances to Level B
harassment isopleths during
simultaneous hammering from two
sources, based on the combined SSL.
Because the calculated Level B
harassment isopleths for two sources are
dependent upon the combined SSL, the
Level B harassment zone for each
combined sound source level included
in Table 8 is consistent, regardless of the
equipment combination. Please refer to
Table 7 to determine which sound
sources apply to each combined SSL.
As noted previously, pile installation
often involves numerous stops and
starts of the hammer for each pile.
Therefore, decibel addition is applied
only when the adjacent continuous
sound sources experience overlapping
sound fields, which generally requires
close proximity of driving locations.
TABLE 8—LEVEL B HARASSMENT
ISOPLETHS FOR MULTIPLE VIBRATORY HAMMER ADDITIONS
Combined SSL
(dB)
164
165
166
167
168
169
170
............................................
............................................
............................................
............................................
............................................
............................................
............................................
Level B
harassment
isopleth
(m) a
8,577
10,000
11,659
13,594
15,849
18,478
21,544
a These larger zones are truncated to the
southeast by islands, which prevent propagation of sound in that direction beyond the confines of Tongass Narrows. To the northwest of
Tongass Narrows, combined sound levels that
exceed 167 dB rms extend into Clarence
Strait before attenuating to sound levels that
are anticipated to be below 120 dB rms.
TABLE 9—LEVEL B HARASSMENT ISOPLETHS FOR SINGLE HAMMER USE BY ACTIVITY AND PILE SIZE
Pile diameter
Vibratory Installation .....................................................................
30-inch ..........................................................................................
24-inch ..........................................................................................
20-inch.
24-inch.
30-inch ..........................................................................................
24-inch.
8-inch.
30-inch ..........................................................................................
24-inch ..........................................................................................
20-inch ..........................................................................................
Vibratory Removal ........................................................................
DTH Rock Sockets .......................................................................
DTH Tension Anchor/Micropile ....................................................
Impact Installation .........................................................................
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Level B
harassment
isopleth
(m)
Activity
Level A Harassment Zones
When the NMFS Technical Guidance
(2016) was published, in recognition of
the fact that ensonified area/volume
could be more technically challenging
to predict because of the duration
component in the new thresholds, we
developed a User Spreadsheet that
includes tools to help predict a simple
isopleth that can be used in conjunction
with marine mammal density or
occurrence to help predict takes. We
note that because of some of the
assumptions included in the methods
used for these tools, we anticipate that
isopleths produced are typically going
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to be overestimates of some degree,
which may result in some degree of
overestimate of takes by Level A
harassment. However, these tools offer
the best way to predict appropriate
isopleths when more sophisticated 3D
modeling methods are not available, and
NMFS continues to develop ways to
quantitatively refine these tools, and
will qualitatively address the output
where appropriate. For stationary
sources such as pile driving or removal
and DTH using any of the methods
discussed above, NMFS’ User
Spreadsheet predicts the closest
distance at which, if a marine mammal
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6,310
5,412
13,594
2,154
1,000
1,000
remained at that distance the whole
duration of the activity, it will incur
PTS. Inputs used in the User
Spreadsheet are reported in Table 10
and Table 11, and the resulting
isopleths are reported below in Table 12
and Table 13. Pile installation and
removal can occur at variable rates, from
a few minutes one day to many hours
the next. ADOT anticipates that one
permanent pile will be installed per day
on 27 non-consecutive days, two
temporary piles will be installed per day
on 10 non-consecutive days, and two
temporary piles will be removed per day
on 10 days.
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TABLE 10—NMFS USER SPREADSHEET INPUTS FOR SINGLE HAMMER USE
Equipment type
Spreadsheet tab used
Weighting Factor Adjustment
(kHz) ......................................
SSL ............................................
Activity duration (hours) within
24 hours .................................
Number of piles per day ...........
Strike rate strikes per second ...
Number of strikes per pile .........
Vibratory
pile driver
(installation
of 30-inch
steel piles)
Vibratory
pile driver
(installation
and removal
of 24-inch
steel piles)
Vibratory
pile driver
(installation
of 20-inch
steel piles)
DTH rock
sockets
(30-inch)
DTH rock
sockets
(24-inch)
DTH tension
anchor
(8-inch)
Impact pile
driver
(30-inch
steel piles)
Impact pile
driver
(24-inch
steel piles)
Impact pile
driver
(20-inch
steel piles)
(A.1)
vibratory
pile driving
(A.1)
vibratory
pile driving
(A.1)
vibratory
pile driving
(E.2)
DTH pile
driving
(E.2)
DTH pile
driving
(E.2)
DTH pile
driving
(E.1)
impact pile
driving
(E.1)
impact pile
driving
(E.1)
impact pile
driving
2.5
2.5
2.5
2
2
2
2
2
2
a 162
a 161
a 161
b 164
b 159
b 144
b 181
b 177
b 177
1
1
....................
....................
1
1
....................
....................
1
1
....................
....................
1–10
1
15
....................
1–10
1
15
....................
2–4
1
25.83
....................
....................
1
....................
50
....................
1
....................
50
....................
1
....................
50
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Notes: Propagation loss coefficient in all cases is 15. Duration estimates for DTH are based on assumption of multiple rock sockets and tension anchors being installed each day, with the maximum duration time for installation per day predicted to be 10 hours for rock socket DTH and 4 hours for tension anchor DTH. For specifics regarding the number of strikes and number of piles that will be used in a given situation, please refer to Table 1 in the notice of proposed IHA (87 FR 5980;
February 2, 2022).
a dB rms at 10m.
b dB SEL at 10m.
Regarding implications for Level A
harassment zones when two vibratory
hammers are operating concurrently,
given the small size of the estimated
Level A harassment isopleths for all
hearing groups during vibratory pile
driving, the zones of any two hammers
are not expected to overlap. Therefore,
compounding effects of multiple
vibratory hammers operating
concurrently are not anticipated, and
NMFS has treated each source
independently.
Regarding implications for Level A
harassment zones when one vibratory
hammer and one DTH hammer are
operating concurrently, combining
isopleths for these sources is difficult
for a variety of reasons. First, vibratory
pile driving relies upon non-impulsive
PTS thresholds, while DTH/rock
hammers use impulsive thresholds.
Second, vibratory pile driving account
for the duration to drive a pile, while
DTH account for strikes per pile. Thus,
it is difficult to measure sound on the
same scale and combine isopleths from
these impulsive and non-impulsive,
continuous sources. Therefore, NMFS
has treated each source independently
at this time.
Regarding the operation of two DTH
hammers concurrently, since DTH
hammers are capable of multiple strikes
per second, there is potential for
multiple DTH/rock hammer sources’
isopleths to overlap in space and time
(a higher strike rate indicates a greater
potential for overlap). Therefore, NMFS
has calculated distances to Level A
harassment isopleths, by hearing group
for simultaneous use of two DTH
hammers (Table 13), using NMFS’ User
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Spreadsheet. The inputs for these
calculations are outlined in Table 11.
When the Level A isopleth of one DTH
sound source encompasses the isopleth
of another DTH sound source, the
sources are considered additive and
combined using the rules in Table 7 as
described above. The number of piles
per day is altered to reflect only a single
pile for all those that overlap in space
and time (i.e., no double counting of
overlapping piles). The maximum strike
rate and duration of the two DTH
systems is used in the User Spreadsheet
calculations.
TABLE 11—NMFS USER SPREADSHEET INPUTS FOR SIMULTANEOUS
USE OF TWO DTH HAMMERS
(E.2) DTH pile
driving
Spreadsheet tab used
Weighting Factor Adjustment (kHz).
SSL(dB SEL at 10m) a
8-in pile/8-in pile .........
8-in pile, 24-in pile ......
8-in pile, 30-in pile ......
24-in pile, 24-in pile ....
24-in pile, 30-in pile ....
30-in pile, 30-in pile ....
Activity duration (minutes)
within 24 hours b.
Number of piles per day b ..
Strike rate (strikes per second).
2.
147.
159.
164.
162.
165.
167.
60, 120, 180 or
240 c.
1.
15 or 25.83 d.
a SSL reflects the combined SSLs calculated
in Table 7.
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b ADOT anticipates that DTH could occur at
one site for up to 10 hours (600 minutes) per
day, and overlap between two sites could
occur for up to 4 hours (240 minutes) per day.
Since the potential overlap in sources is accounted for in the SSL adjustment, and the
total potential duration (even with two hammers) is accounted for in the ‘‘Activity duration
(minutes) within 24 hours,’’ the ‘‘Number of
piles per day’’ is assumed to be 1.
c Duration will vary.
d 25.83 for combinations that include 8-in
piles. 15 for all other combinations.
Level A harassment thresholds for
impulsive sound sources (impact pile
driving and DTH) are defined for both
SELcum and Peak SPL with the
threshold that results in the largest
modeled isopleth for each marine
mammal hearing group used to establish
the Level A harassment isopleth. In this
project, Level A harassment isopleths
based on cumulative sound exposure
level (SELcum) were always larger than
those based on Peak SPL (for both single
hammer use and simultaneous use of
two hammers). It should be noted that
there is a duration component when
calculating the Level A harassment
isopleth based on SELcum, and this
duration depends on the number of
piles that will be driven in a day and
strikes per pile. For some activities,
ADOT plans to drive variable numbers
of piles per day throughout the project
(See ‘‘Average Piles per Day (Range)’’ in
Table 1 in the notice of proposed IHA
(87 FR 5980; February 2, 2022)), and
determine at the beginning of each pile
driving day, the maximum number or
duration piles will be driven that day.
Here, this flexibility has been accounted
for by modeling multiple durations for
the activity, and determining the
relevant isopleths.
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TABLE 12—DISTANCES TO LEVEL A HARASSMENT ISOPLETHS, BY HEARING GROUP, AND AREA OF LEVEL A HARASSMENT
ZONES, FOR SINGLE HAMMER USE DURING PILE INSTALLATION AND REMOVAL
Activity
Pile diameter(s)
Minutes per pile or
strikes per pile
Vibratory Installation ........
30-inch ..................
24-inch b ...............
20-inch ..................
24-inch ..................
30-inch ..................
60 minutes ............
60 minutes ............
60 minutes ............
60 minutes ............
60 minutes ............
300 minutes ..........
600 minutes ..........
60 minutes ............
300 minutes ..........
600 minutes ..........
120 minutes ..........
240 minutes ..........
50 strikes ..............
50 strikes ..............
50 strikes ..............
Level A harassment isopleth
(m)
LF
Vibratory Removal ...........
DTH Rock Sockets ..........
24-inch ..................
DTH Tension Anchor .......
8-inch ....................
Impact Installation ...........
30-inch ..................
24-inch ..................
20-inch ..................
a Please
MF
8
7
7
7
773
2,258
3,584
359
1,048
1,664
82
130
100
54
54
HF
1
1
1
1
28
81
128
13
38
60
3
5
4
2
2
PW
12
11
11
11
920
2,690
4,269
427
1,249
1,982
98
155
119
65
65
Level A
harassment areas
2
(km ) all hearing
groups a
OW
5
5
5
5
414
1,209
1,918
192
561
891
44
70
54
29
29
1
1
1
1
31
88
140
15
41
65
4
6
4
3
3
<0.1
<0.1
<0.1
<0.1
<0.9
<3.5
<6.6
<0.2
<1.4
<2.4
<0.1
<0.1
<0.1
<0.1
<0.1
refer to Table 6–4 of ADOT’s IHA application for hearing group-specific areas.
vibratory installation and removal.
b Includes
TABLE 13—DISTANCES TO LEVEL A HARASSMENT ISOPLETHS, BY HEARING GROUP FOR SIMULTANEOUS USE OF TWO
DTH HAMMERS
Level A harassment isopleth (m)
Activity combination
Duration
LF
8-in pile, 8-in pile .....................................
60
120
180
240
60
120
180
240
60
120
180
240
60
120
180
240
60
120
180
240
60
120
180
240
8-in pile, 24-in pile ...................................
8-in pile, 30-in pile ...................................
24-in pile, 24-in pile .................................
24-in pile, 30-in ........................................
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30-in pile, 30-in pile .................................
Regarding implications for impact
hammers used in combination with a
vibratory hammer or DTH drill, the
likelihood of these multiple sources’
isopleths to completely overlap in time
is slim primarily because impact pile
driving is intermittent. Furthermore,
non-impulsive, continuous sources rely
upon non-impulsive TTS/PTS
thresholds, while impact pile driving
uses impulsive thresholds, making it
difficult to calculate isopleths that may
overlap from impact driving and the
simultaneous action of a non-impulsive
continuous source or one with multiple
strikes per second. Thus, with such slim
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MF
82
130
170
206
515
817
1,071
1,297
1,109
1,761
2,307
2,796
568
902
1,181
1,431
900
1,429
1,873
2,268
1,224
1,943
2,545
3,084
HF
3
5
6
7
18
29
38
46
40
63
82
99
20
32
42
51
32
51
67
81
44
69
91
110
PW
98
155
202
245
613
974
1,276
1,545
1,321
2,097
2,748
3,329
677
1,074
1,407
1,705
1,072
1,702
2,230
2,702
1,458
2,314
3,032
3,673
OW
44
70
91
110
276
437
573
694
594
942
1,235
1,496
304
483
632
766
482
765
1,002
1,214
655
1,040
1,362
1,650
3
5
7
8
20
32
42
51
43
69
90
109
22
35
46
56
35
56
73
88
48
76
99
120
potential for multiple different sources’
isopleths to overlap in space and time,
specifications should be entered as
‘‘normal’’ into the User Spreadsheet for
each individual source separately.
the estimated take, including as a
percentage of population for each of the
species, is shown in Table 14.
Marine Mammal Occurrence and Take
Calculation and Estimation
Steller sea lion abundance in the
Tongass Narrows area is not well
known. No systematic studies of Steller
sea lions have been conducted in or
near the Tongass Narrows area. Steller
sea lions are known to occur year-round
and local residents report observing
Steller sea lions approximately once or
twice per week (based on
communication outlined in Section 6 of
ADOT’s IHA application). Abundance
In this section we provide the
information about the presence, density,
or group dynamics of marine mammals
that will inform the take calculations.
Additionally, we describe how the
occurrence information is brought
together to produce a quantitative take
estimate for each phase. A summary of
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appears to increase during herring runs
(March to May) and salmon runs (July
to September). Group sizes may reach
up to 6 to 10 individuals (Freitag 2017
as cited in 83 FR 37473; August 1,
2018), though groups of up to 80
individuals have been observed (HDR,
Inc. 2003).
ADOT conservatively estimates that
one group of 10 Steller sea lions may be
present in the project area each day, but
this occurrence rate may as much as
double (20 Steller sea lions per day)
during periods of increased abundance
associated with the herring and salmon
runs (March to May and July to
September). Therefore, ADOT
anticipates that two large groups (20
individuals) may be taken by Level B
harassment each day during these
months. To be conservative, we assume
all 91 days of work could be completed
during these months of increased
abundance and thus estimate 1,820
potential takes by Level B harassment of
Steller sea lions in Tongass Narrows
(i.e., 2 groups of 10 sea lions per day ×
91 construction days = 1,820 takes by
Level B harassment; Table 14).
ADOT estimates that simultaneous
use of two hammers (any combination)
could occur on up to 44 days during the
project. On those days, Level B
harassment zones will extend into
Clarence Strait. Steller sea lions are
known to swim across Clarence Strait
and to use offshore areas with deeper
waters, although no estimates of at-sea
density or abundance in Clarence Strait
are available. Therefore, ADOT has
conservatively estimated, and NMFS
concurs, that during the 44 days with
potential simultaneous use of two
hammers, a group of 10 Steller sea lions
may occur in the portion of the Level B
harassment zone in Clarence Strait each
day (one group of 10 sea lions per day
× 44 days = 440 individuals). Therefore,
the preliminary sum of estimated takes
by Level B harassment of Steller sea
lions between Tongass Narrows and
Clarence Strait is 2,260 (1,820 + 440 =
2,260 takes by Level B harassment).
The largest Level A harassment zone
for otariid pinnipeds could extend 140
m from the noise source for 10 hours of
DTH using a single hammer, or 120m
from the noise source for 4 hours of
DTH using two hammers for 30-in piles
simultaneously. (As noted previously,
ADOT estimates that simultaneous use
of any two hammer types will occur on
no more than 44 days). Zones for shorter
durations and other activities will be
smaller (Table 12). For some DTH
activities, the estimated Level A
harassment zone is larger than the
shutdown zone, and therefore, some
Level A harassment could occur.
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Further, while unlikely, it is possible
that a Steller sea lion could enter a
shutdown zone without detection given
the various obstructions along the
shoreline, and remain in the zone long
enough to be taken by Level A
harassment before being observed and a
shutdown occurring. ADOT therefore
requested, and NMFS authorized, one
take by Level A harassment on each of
the 91 construction days (91 takes by
Level A harassment). Authorized take
by Level B harassment was calculated as
the total calculated Steller sea lion takes
by Level B harassment minus the takes
by Level A harassment (2,260 takes¥91
takes by Level A harassment) for a total
of 2,169 takes by Level B harassment.
Therefore, ADOT requested, and NMFS
authorized, 91 takes of Steller sea lion
by Level A harassment and 2,169 takes
of Steller sea lion by Level B harassment
(2,260 total takes of Steller sea lion;
Table 14).
Harbor Seal
Harbor seal densities in the Tongass
Narrows area are not well known. No
systematic studies of harbor seals have
been conducted in or near Tongass
Narrows. They are known to occur yearround with little seasonal variation in
abundance (Freitag 2017 as cited in 83
FR 37473; August 1, 2018) and local
experts estimate that there are about 1
to 3 harbor seals in Tongass Narrows
every day, in addition to those that
congregate near the seafood processing
plants and fish hatcheries. NMFS has
indicated that the maximum group size
in Tongass Narrows is three individuals
(83 FR 22009; May 11, 2018); however,
ADOT monitoring in March 2021
observed several groups of up to 5
individuals. Based on this knowledge,
the expected maximum group size in
Tongass Narrows is five individuals.
Harbor seals are known to be curious
and may approach novel activity. For
these reasons ADOT conservatively
estimates that up to two groups of 5
harbor seals per group could be taken by
Level B harassment due to projectrelated underwater noise each
construction day for a total of 910 takes
by Level B harassment of harbor seal in
Tongass Narrows (i.e., 2 groups of 5
harbor seals per day × 91 construction
days = 910 total takes by Level B
harassment of harbor seal; Table 14).
As noted above, ADOT estimates that
simultaneous use of two hammers (any
combination) could occur on up to 44
days during the project. On those days,
Level B harassment zones will extend
into Clarence Strait. Harbor seals are
known to swim across Clarence Strait,
although no estimates of at-sea density
or abundance in Clarence Strait are
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15397
available. It is likely that harbor seal
abundance in Clarence Strait is lower
than in Tongass Narrows, as harbor
seals generally prefer nearshore waters.
Therefore, ADOT has conservatively
estimated, and NMFS concurs, that
during the 44 days with potential
simultaneous use of two hammers, a
group of 5 harbor seals may occur in the
portion of the Level B harassment zone
in Clarence Strait each day (one group
of 5 harbor seals per day × 44 days = 220
individuals). Therefore, the sum of total
estimated takes by Level B harassment
of harbor seals between Tongass
Narrows and Clarence Strait is 1,130
(910 + 220 = 1,130 takes by Level B
harassment).
The largest Level A harassment zone
for harbor seals could extend 1,918 m
from the noise source for 10 hours of
DTH using a single hammer, or 1,640 m
from the noise source for 4 hours of
DTH using two hammers for 30-in piles
simultaneously. (As noted previously,
ADOT estimates that simultaneous use
of any two hammer types will occur on
no more than 44 days). Zones for shorter
durations and other activities will be
smaller (Table 12). Due to practicability
concerns, NMFS is requiring a 200 m
shutdown zone for harbor seals during
24-in and 30-in DTH activities (Table
15). Therefore, for some DTH activities,
the estimated Level A harassment zone
is larger than the shutdown zone, and
therefore, some Level A harassment
could occur. Harbor seals may enter and
remain within the area between the
Level A harassment zone and the
shutdown zone for a duration long
enough to be taken by Level A
harassment. Additionally, while
unlikely, it is possible that a harbor seal
could enter a shutdown zone without
detection given the various obstructions
along the shoreline, and remain in the
zone for a duration long enough to be
taken by Level A harassment before
being observed and a shutdown
occurring.
To calculate take by Level A
harassment, ADOT first calculated the
ratio of the maximum Level A
harassment isopleth for 30-in DTH using
a single hammer minus the shutdown
zone isopleth (1,918 m¥200 m
shutdown zone = 1,718 m) to the Level
B harassment zone isopleth (13,594 m;
1,718 m/13,594 m = 0.1264). ADOT
multiplied the resulting ratio by the
total potential take in Tongass Narrows,
resulting in 116 takes by Level A
harassment (i.e., 910 takes by Level B
harassment × 0.1264 = 116 takes by
Level A harassment). NMFS reviewed,
and concurs with and adopts this
method. (Potential operation of two
DTH hammers for 24-in/30-in or 30-in/
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30-in pile combinations would result in
larger Level A harassment isopleths
than 1,918 m, however, such concurrent
work will rarely occur, if at all, and
therefore, NMFS expects that
calculating Level A harassment take
using those zones would be overly
conservative and unrealistic. Moreover,
since the method used above assumes
30-inch DTH on all days it provided a
precautionary cushion since activities
with smaller Level A harassment zone
sizes will occur on many days.)
Authorized take by Level B harassment
was calculated as the total calculated
harbor seal takes by Level B harassment
minus the takes by Level A harassment
(1,130 takes¥116 takes by Level A
harassment) for a total of 1,014 takes by
Level B harassment. ADOT therefore
requested, and NMFS authorized, 116
takes of harbor seal by Level A
harassment and 1,014 takes of harbor
seal by Level B harassment (1,130 total
takes of harbor seal; Table 14).
Harbor Porpoise
Harbor porpoises are non-migratory;
therefore, our occurrence estimates are
not dependent on season. Freitag (2017
as cited in 83 FR 37473; August 1, 2018)
observed harbor porpoises in Tongass
Narrows zero to one time per month.
Harbor porpoises observed in the project
vicinity typically occur in groups of one
to five animals with an estimated
maximum group size of eight animals
(83 FR 37473, August 1, 2018, Solstice
2018). ADOT’s 2020 and 2021
monitoring program in Tongass Narrows
did not result in sightings of this
species; however, ADOT assumes an
occurrence rate of one group per month
in the following take estimations. For
our analysis, we are considering a group
to consist of five animals. Based on
Freitag (2017), and supported by the
reports of knowledgeable locals as
described in ADOT’s application, ADOT
estimates that one group of five harbor
porpoises could enter Tongass Narrows
and potentially taken by Level B
harassment due to project-related noise
each month for a total of 15 potential
harbor porpoise takes by Level B
harassment in Tongass Narrows (i.e., 1
group of 5 individuals × 3 months (91
days) = 15 harbor porpoises).
As noted above, ADOT estimates that
simultaneous use of two hammers (any
combination) could occur on up to 44
days during the project. On those days,
the Level B harassment zone will extend
into Clarence Strait. Harbor porpoises
are known to swim across Clarence
Strait and to use other areas of deep,
open waters. Dahlheim et al. (2015)
estimated a density of 0.02 harbor
porpoises/km2 in an area that
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encompasses Clarence Strait. ADOT
estimates, and NMFS concurs that
during the 44 days with potential
simultaneous use of two hammers, 17
harbor porpoises (0.02 harbor porpoises/
km2 × 18.5 km2 × 44 days = 17 harbor
porpoises) may occur in the portion of
the Level B harassment zone in Clarence
Strait during the project (though ADOT
and NMFS anticipate that this is a
conservative estimate, given the entire
18.5 km2 area will rarely be ensonified
above the Level B harassment
threshold). Therefore, the sum of total
estimated takes by Level B harassment
of harbor porpoise between Tongass
Narrows and Clarence Strait is 32 (15 +
17 = 32 takes by Level B harassment).
The largest Level A harassment zone
for harbor porpoises extends 4,269 m
from the noise source for 10 hours of
DTH using a single hammer, and 3,673
m from the noise source for 4 hours of
DTH using two hammers for 30-in piles
simultaneously. (As noted previously,
ADOT estimates that simultaneous use
of any two hammer types will occur on
no more than 44 days). Zones for shorter
durations and other activities will be
smaller (Table 12). Due to practicability
concerns, NMFS is requiring a 500 m
shutdown zone for high frequency
cetaceans during 24-in and 30-in DTH
activities. Therefore, for some DTH
activities, the estimated Level A
harassment zone is larger than the
shutdown zone, and therefore, some
Level A harassment could occur. Harbor
porpoises may enter and remain within
the area between the Level A
harassment zone and the shutdown
zone for a duration long enough to be
taken by Level A harassment.
Additionally, given the large size of
required shutdown zones for some
activities and the cryptic nature of
harbor porpoises, it is possible that a
harbor porpoise could enter a shutdown
zone without detection and remain in
the zone for a duration long enough to
be taken by Level A harassment before
being observed and a shutdown
occurring.
To calculate take by Level A
harassment, ADOT first calculated the
ratio of the maximum Level A
harassment isopleth for 30-in DTH using
a single hammer minus the shutdown
zone isopleth (4,269 m¥500 m = 3,769
m) to the Level B harassment zone
isopleth (13,594 m; 3,769/13,594 =
0.2773). ADOT multiplied the resulting
ratio by the total potential take in
Tongass Narrows, resulting in 5 takes by
Level A harassment (i.e., 15 takes by
Level B harassment × 0.2773 = 5 takes
by Level A harassment). NMFS
reviewed and concurs with this method.
(Potential operation of two DTH
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hammers for 24-in/30-in or 30-in/30-in
pile combinations would result in larger
Level A harassment isopleths than 4,269
m, however, such concurrent work
would rarely occur, if at all, and
therefore, as described above, NMFS
expects that calculating Level A
harassment take using those zones is
unnecessary.) Authorized take by Level
B harassment was calculated as the total
calculated harbor porpoise takes by
Level B harassment minus the takes by
Level A harassment (32 takes¥5 takes
by Level A harassment) for a total of 27
takes by Level B harassment. ADOT
therefore requested and NMFS
authorized 5 takes by Level A
harassment and 27 takes by Level B
harassment (32 total takes of harbor
porpoise; Table 14).
Dall’s Porpoise
Dall’s porpoises are expected to only
occur in the project area a few times per
year. Their relative rarity is supported
by Jefferson et al.’s (2019) presentation
of historical survey data showing very
few sightings in the Ketchikan area and
conclusion that Dall’s porpoise
generally are rare in narrow waterways,
like the Tongass Narrows. ADOT’s
monitoring program from 2020 and 2021
recorded one sighting of 6 individuals
over 23 days of observation, 16 days of
observations with no sightings, and two
sightings of 10 individuals in 14 days of
observation; this equates to one sighting
every approximately 17 days (DOT&PF
2020, 2021a, 2021b, 2021c, 2021d) or
approximately two sightings per month.
This species is non-migratory; therefore,
the occurrence estimates are not
dependent on season. ADOT anticipates
that one large Dall’s porpoise pod (12
individuals) may be present in the
project area and exposed to project
related underwater noise twice each
month during 3 months of construction
(91 days rounded to 3 months) for a
total of 72 potential takes by Level B
harassment in Tongass Narrows (i.e., 2
groups of 12 Dall’s porpoises per month
× 3 months = 72 potential takes by Level
B harassment).
As noted above, ADOT estimates that
simultaneous use of two hammers (any
combination) could occur on up to 44
days during the project. On those days,
the Level B harassment zone will extend
into Clarence Strait, where Dall’s
porpoises are known to occur. Jefferson
et al. (2019) estimated an average
density of 0.19 Dall’s porpoises/km2 in
Southeast Alaska. ADOT estimates, and
NMFS concurs, that during the 44 days
with potential simultaneous use of two
hammers, 155 Dall’s porpoises (0.19
Dall’s porpoises/km2 × 18.5 km2 × 44
days = 155 Dall’s porpoises) may occur
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in the portion of the Level B harassment
zone in Clarence Strait during the
project (though ADOT and NMFS
anticipate that this is a conservative
estimate, given the entire 18.5 km2 area
will rarely be ensonified above the Level
B harassment threshold). Therefore, the
sum of total estimated takes by Level B
harassment of harbor porpoise between
Tongass Narrows and Clarence Strait is
227 (72 + 155= 227 takes by Level B
harassment).
The largest Level A harassment zone
for Dall’s porpoises extends 4,269 m
from the noise source for 10 hours of
DTH using a single hammer, and 3,673
m from the noise source for 4 hours of
DTH using two hammers for 30-in piles
simultaneously. (As noted previously,
ADOT estimates that simultaneous use
of any two hammer types will occur on
no more than 44 days.) Zones for shorter
durations and other activities will be
smaller (Table 12). Due to practicability
concerns, NMFS proposes to require a
500 m shutdown zone for high
frequency cetaceans during 24-in and
30-in DTH activities. Therefore, for
some DTH activities, the estimated
Level A harassment zone is larger than
the shutdown zone, and therefore, some
Level A harassment could occur. Dall’s
porpoises may enter and remain within
the area between the Level A
harassment zone and the shutdown
zone and be exposed to sound levels for
a duration long enough to be taken by
Level A harassment. Additionally, given
the large size of the required shutdown
zones for some activities, it is possible
that a Dall’s porpoise could enter a
shutdown zone without detection and
remain in the zone for a duration long
enough to taken by Level A harassment
before being observed and a shutdown
occurring.
To calculate take by Level A
harassment, ADOT first calculated the
ratio of the maximum Level A
harassment isopleth for 30-in DTH using
a single hammer minus the shutdown
zone isopleth (4,269 m¥500 m = 3,769
m) to the Level B harassment zone
isopleth (13,594 m; 3,769/13,594 =
0.2773). ADOT multiplied the resulting
ratio by the total potential take in
Tongass Narrows, resulting in 20 takes
by Level A harassment (i.e., 72 takes by
Level B harassment × 0.2773 = 20 takes
by Level A harassment). NMFS revised
and concurs with this method.
(Potential operation of two DTH
hammers for 24-in/30-in or 30-in/30-in
pile combinations would result in larger
Level A harassment isopleths than 4,269
m, however, such concurrent work
would rarely occur, if at all, and
therefore, as described above, NMFS
expects that calculating Level A
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harassment take using those zones is
unnecessary.) Authorized take by Level
B harassment was calculated as the total
calculated Dall’s porpoise takes by Level
B harassment minus the takes by Level
A harassment (227 takes¥20 takes by
Level A harassment) for a total of 207
takes by Level B harassment. ADOT
therefore requested and NMFS
authorized 20 takes by Level A
harassment, and 207 takes by Level B
harassment (227 total takes of Dall’s
porpoise; Table 14).
Pacific White-Sided Dolphin
Pacific white-sided dolphins do not
generally occur in the shallow, inland
waterways of Southeast Alaska. There
are no records of this species occurring
in Tongass Narrows, and it is
uncommon for individuals to occur in
the project area. However, historical
sightings in nearby areas (Dahlheim and
Towell 1994; Muto et al. 2018) and
recent fluctuations in distribution and
abundance mean it is possible the
species could be present.
To account for the possibility that this
species could be present in the project
area, ADOT conservatively estimates,
and NMFS concurs, that one large group
(92 individuals) of Pacific white-sided
dolphins may be taken by Level B
harassment in Tongass Narrows during
the activity.
As noted above, ADOT estimates that
simultaneous use of two hammers (any
combination) could occur on up to 44
days during the project. On those days,
the Level B harassment zone will extend
into Clarence Strait. However, no
additional takes of Pacific white-sided
dolphin are anticipated to occur due to
simultaneous use of two hammers,
given that Pacific white-sided dolphins
are uncommon in the project area.
Therefore, NMFS authorized 92 takes by
Level B harassment of Pacific whitesided dolphins.
ADOT did not request, nor did NMFS
authorize take by Level A harassment
for this activity given that Pacific whitesided dolphins are uncommon in the
project area. Further, considering the
small Level A harassment zones for
mid-frequency cetaceans (Table 12 and
Table 13) in comparison to the required
shutdown zones, it is unlikely that a
Pacific white-sided dolphin will enter
and remain within the area between the
Level A harassment zone and the
shutdown zone for a duration long
enough to be taken by Level A
harassment.
Killer Whale
Killer whales are observed in Tongass
Narrows irregularly with peaks in
abundance between May and July.
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During 7 months of intermittent marine
mammal monitoring (October 2020–
February 2021; May–June 2021), there
were five killer whale sightings in 4
months (November, February, May,
June) totaling 22 animals; sightings
occurred on 5 out of 88 days of
monitoring (DOT&PF 2020, 2021a,
2021b, 2021c, 2021d). Pod sizes ranged
from two to eight animals (DOT&PF
2020, 2021a, 2021b, 2021c, 2021d).
Previous incidental take authorizations
in the Ketchikan area have estimated
killer whale occurrence in Tongass
Narrows at one pod per month, except
during the peak period of May to July
when estimates have included two pods
per month (Freitag 2017 as cited in 83
FR 37473; August 1, 2018 and 83 FR
34134; July 17, 2019).
As noted above, ADOT estimates that
simultaneous use of two hammers (any
combination) could occur on up to 44
days during the project. On those days,
the Level B harassment zone will extend
into Clarence Strait. In estimating take
by Level B harassment, ADOT assumed
a pod size of 12 killer whales, that all
91 days of work will occur between May
and July during the peaks in abundance,
and that therefore, 2 pods may occur
within the Level B harassment zone
(including both Tongass Narrows and
Clarence Strait) during each month of
work, for a total of 72 takes by Level B
harassment (2 groups × 12 individuals ×
3 months = 72 killer whales). Therefore,
ADOT estimates that a total of 72 killer
whales may be taken by Level B
harassment (i.e., 2 pods of 12
individuals per month × 3 months (91
days) = 72 takes by Level B harassment).
NMFS reviewed and concurs with this
method, and authorized 72 takes by
Level B harassment of killer whale.
ADOT did not request, nor did NMFS
authorize take by Level A harassment of
killer whales for this activity.
Considering the small Level A
harassment zones for mid-frequency
cetaceans (Table 12 and Table 13) in
comparison to the required shutdown
zones, it is unlikely that a killer whale
will enter and remain within the area
between the Level A harassment zone
and the shutdown zone for a duration
long enough to be taken by Level A
harassment.
Humpback Whale
As discussed in the Description of
Marine Mammals in the Area of
Specified Activities section, locals have
observed humpback whales an average
of about once per week in Tongass
Narrows, but there is evidence to
suggest occurrence may be higher
during some periods of the year. The
December 19, 2019 Biological Opinion
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stated that based on observations by
local experts, approximately one group
of two individuals will occur in Tongass
Narrows during ADOT’s activity two
times per seven days during pile
driving, pile removal, and DTH
activities throughout the year. The
assumption was based on differences in
abundance throughout the year, recent
observations of larger groups of whales
present during summer, and a higher
than average frequency of occurrence in
recent months (NMFS 2019). ADOT’s
2020 and 2021 monitoring program
documented a similar sighting rate, with
30 humpback whale sightings over 53
days of in-water pile driving; some of
the sightings were believed to be
repeated sightings of the same
individual (DOT&PF 2020, 2021a,
2021b, 2021c, 2021d). ADOT therefore
predicts, and NMFS concurs, that one
group of two individuals may occur
within the Level B harassment zones
twice per week during the planned
activities. As noted previously, ADOT
estimates that pile driving will occur
over the course of 91 days (13 weeks).
Therefore, ADOT estimates, and NMFS
concurs that 52 takes by Level B
harassment of humpback whales (1
group of 2 individuals × 2 groups per
week × 13 weeks = 52 takes by Level B
harassment) from the Central North
Pacific stock may occur in Tongass
Narrows.
As noted above, ADOT estimates that
simultaneous use of two hammers (any
combination) could occur on up to 44
days during the project. On those days,
the Level B harassment zone will extend
into Clarence Strait. Local specialists
estimated that approximately four
humpback whales could pass through or
near the portion of the Level B
harassment zone in Clarence Strait each
day. Therefore, ADOT estimates, and
NMFS concurs, that during the 44 days
with potential simultaneous use of two
hammers, 176 takes by Level B
harassment of humpback whale could
occur in Clarence Strait (4 humpback
whales × 44 days = 176 takes by Level
B harassment). Therefore, the sum of
total estimated takes by Level B
harassment of humpback whale between
Tongass Narrows and Clarence Strait is
228 (52 + 176 = 228 takes by Level B
harassment), and NMFS authorized 228
takes by Level B harassment of
humpback whale.
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As noted previously, Wade et al.
(2021) estimates that approximately 2
percent of all humpback whales in
Southeast Alaska and northern British
Columbia are of the Mexico DPS, while
all others are of the Hawaii DPS.
However, NMFS has conservatively
assumed here that 6.1 percent of the
total humpback population in Southeast
Alaska is from the Mexico DPS (Wade
et al. 2016). Therefore, of the 228 takes
of humpback whale authorized, NMFS
expects that a total of 14 takes will be
of individuals from the Mexico DPS.
NMFS expects that all other instances of
take will be from the non-listed Hawaii
DPS.
Take by Level A harassment of
humpback whales is neither anticipated
nor authorized because of the expected
effectiveness of the required monitoring
and mitigation measures (see Mitigation
Measures section below for more
details). For all pile driving and DTH
activities, the shutdown zone exceeds
the calculated Level A harassment zone.
Humpbacks are usually readily visible,
and therefore, we expect protected
species observers (PSOs) to be able to
effectively implement the required
shutdown measures prior to any
humpback whales incurring PTS within
Level A harassment zones.
Minke Whales
Minke whales may be present in
Tongass Narrows year-round. Their
abundance throughout Southeast Alaska
is very low, and anecdotal reports have
not included minke whales near the
project area. ADOT’s monitoring
program in Tongass Narrows also did
not report any minke whale sightings.
However, minke whales are distributed
throughout a wide variety of habitats
and could occur near the project area.
Minke whales are generally sighted as
solo individuals (Dahlheim et al. 2009).
As noted above, ADOT estimates that
simultaneous use of two hammers (any
combination) could occur on up to 44
days during the project. On those days,
the Level B harassment zone will extend
into Clarence Strait. Based on Freitag
(2017; as cited in 83 FR 37473; August
1, 2018 and 83 FR 34134; July 17, 2019),
ADOT estimates that three individual
minke whales may occur near or within
the Level B harassment zone (including
both Tongass Narrows and Clarence
Strait) every four months. Based on that
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estimated occurrence rate, NMFS
estimates that 3 minke whales may
occur in the Level B harassment zone
during the planned activities (occurring
over approximately 3 months), and
authorized 3 takes by Level B
harassment of minke whales (Table 14).
The largest Level A harassment zone
for minke whale extends 3,584 m from
the noise source for 10 hours of DTH
using a single hammer, and 3,084 m
from the noise source for 4 hours of
DTH using two hammers for 30-in piles
simultaneously. (As noted previously,
ADOT estimates that simultaneous use
of any two hammer types will occur on
no more than 44 days.) Zones for shorter
durations and other activities will be
smaller (Table 13). NMFS required a
1,500 m shutdown zone for minke
whales during 24-in and 30-in DTH
activities. Therefore, for some DTH
activities, the estimated Level A
harassment zone is larger than the
required shutdown zone, and Level A
harassment could occur.
To calculate take by Level A
harassment, ADOT first calculated the
ratio of the maximum Level A
harassment isopleth for 30-in DTH using
a single hammer minus the shutdown
zone isopleth (3,584 m¥1,500 m =
2,084 m) to the Level B harassment zone
isopleth (13,594 m; 2,084 m/13,594 m =
0.1533). ADOT multiplied the resulting
ratio by the total potential take by Level
B harassment, resulting in 1 take by
Level A harassment (i.e., 3 takes by
Level B harassment × 0.1533 = 1 take by
Level A harassment). NMFS reviewed
and concurs with this method.
(Potential operation of two DTH
hammers for 24-in/30-in or 30-in/30-in
pile combinations would result in larger
Level A harassment isopleths than
4,269 m, however, such concurrent
work would rarely occur, if at all, and
therefore, as described above NMFS
expects that calculating Level A
harassment take using those zones is
unnecessary.) Take by Level B
harassment was calculated as the total
potential minke whale takes by Level B
harassment minus the takes by Level A
harassment. ADOT therefore requested,
and NMFS authorized 1 take by Level A
harassment and 2 takes by Level B
harassment (3 total takes of minke
whale; Table 14).
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TABLE 14—AUTHORIZED TAKE AS A PERCENTAGE OF STOCK ABUNDANCE, BY STOCK AND HARASSMENT TYPE
Authorized take
Species
DPS/stock
Level B
harassment
Percent
of stock
Total
Steller sea lion ..................................
Harbor seal .......................................
Harbor porpoise ................................
Dall’s porpoise ..................................
Pacific white-sided dolphin ...............
Eastern U.S. .....................................
Clarence Strait .................................
Southeast Alaska .............................
Alaska ...............................................
North Pacific .....................................
91
116
5
20
0
2,169
1,014
27
207
92
2,260
1,130
32
227
92
Killer whale ........................................
Alaska Resident ...............................
West Coast Transient
Northern Resident
Central North Pacific ........................
Alaska ...............................................
0
72
72
Humpback whale ..............................
Minke whale ......................................
a Conservatively
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Level A
harassment
a 3.1
a 20.1
a 23.8
0
1
228
2
228
3
2.3
N/A
assumes that all 72 takes occur to each stock.
Mitigation Measures
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.
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
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of a military readiness activity,
personnel safety, practicality of
implementation, and impact on the
effectiveness of the military readiness
activity.
Because of the need for an ESA
Section 7 consultation for effects of the
project on ESA listed humpback whales,
there are a number of mitigation
measures that go beyond, or are in
addition to, typical mitigation measures
we would otherwise require for this sort
of project. However, these measures are
typical for actions in the Ketchikan area.
The mitigation measures included
herein include measures that align with
the 2019 Biological Opinion. ADOT
must employ the following mitigation
measures as included in the proposed
IHA:
• Avoid direct physical interaction
with marine mammals during
construction activity. If a marine
mammal comes within 10 m of such
activity, operations must cease and
vessels must reduce speed to the
minimum level required to maintain
steerage and safe working conditions
(note that NMFS expects that a 10 m
shutdown zone is sufficient to avoid
direct physical interaction with marine
mammals, but ADOT conservatively
proposed a 20 m shutdown zone to
avoid physical interaction for in-water
other than vessel transit);
• Ensure that construction
supervisors and crews, the monitoring
team and relevant ADOT staff are
trained prior to the start of all pile
driving and DTH activity, so that
responsibilities, communication
procedures, monitoring protocols, and
operational procedures are clearly
understood. New personnel joining
during the project must be trained prior
to commencing work;
• Pile driving activity must be halted
upon observation of either a species for
which incidental take is not authorized
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or a species for which incidental take
has been authorized but the authorized
number of takes has been met, entering
or within the harassment zone;
• For any marine mammal species for
which take by Level B harassment has
not been requested or authorized, inwater pile installation/removal and DTH
will shut down immediately when the
animals are sighted;
• Employ PSOs and establish
monitoring locations as described in the
Marine Mammal Monitoring Plan and
Section 5 of the IHA. The Holder must
monitor the project area to the
maximum extent possible based on the
required number of PSOs, required
monitoring locations, and
environmental conditions. For all pile
driving and removal at least three PSOs
must be used;
• The placement of the PSOs during
all pile driving and removal and DTH
activities will ensure that the entire
shutdown zone is visible during pile
installation;
• Monitoring must take place from 30
minutes prior to initiation of pile
driving or DTH activity (i.e., preclearance monitoring) through 30
minutes post-completion of pile driving
or DTH activity;
• If in-water work ceases for more
than 30 minutes, ADOT will conduct
pre-clearance monitoring of both the
Level B harassment zone and shutdown
zone;
• Pre-start clearance monitoring must
be conducted during periods of
visibility sufficient for the lead PSO to
determine that the shutdown zones
indicated in Table 15 are clear of marine
mammals. Pile driving may commence
following 30 minutes of observation
when the determination is made that the
shutdown zones are clear of marine
mammals;
• If a marine mammal is observed
entering or within the shutdown zones
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indicated in Table 15, pile driving must
be delayed or halted. If pile driving is
delayed or halted due to the presence of
a marine mammal, the activity may not
commence or resume until either the
animal has voluntarily exited and been
visually confirmed beyond the
shutdown zone (Table 15) or 15 minutes
have passed without re-detection of the
animal (30 minutes for humpback
whales);
• As required by the 2019 Biological
Opinion, if waters exceed a sea state
that restricts the PSOs’ ability to make
observations within the shutdown zone,
in-water pile installation and removal
will cease. Pile installation and removal
will not be initiated or continue until
the appropriate shutdown zone is
visible in its entirety;
• For humpback whales, if the
boundaries of the harassment zone have
not been monitored continuously during
a work stoppage, the entire harassment
zone will be surveyed again to ensure
that no humpback whales have entered
the harassment zone that were not
previously accounted for;
• In-water activities will take place
only: Between civil dawn and civil dusk
when PSOs can effectively monitor for
the presence of marine mammals;
during conditions with a Beaufort Sea
State of 4 or less; when the entire
shutdown zone and adjacent waters are
visible (e.g., monitoring effectiveness is
not reduced due to rain, fog, snow, etc.).
Pile driving may continue for up to 30
minutes after sunset during evening
civil twilight, as necessary to secure a
pile for safety prior to demobilization
for the evening. PSO(s) will continue to
observe shutdown and monitoring zones
during this time. The length of the postactivity monitoring period may be
reduced if darkness precludes visibility
of the shutdown and monitoring zones;
• Vessel operators will implement the
following required measures: Maintain a
watch for marine mammals at all times
while underway; remain at least and at
least 91 m (100 yards (yd)) from all
other listed marine mammals, travel at
less than 5 knots (9 km/hr) when within
274 m (300 yd) of a whale; avoid
changes in direction and speed when
within 274 m (300 yd) of whales, unless
doing so is necessary for maritime
safety; not position vessel(s) in the path
of whales, and will not cut in front of
whales in a way or at a distance that
causes the whales to change their
direction of travel or behavior
(including breathing/surfacing pattern);
check the waters immediately adjacent
to the vessel(s) to ensure that no whales
will be injured when the propellers are
engaged; adhere to the Alaska
Humpback Whale Approach
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Regulations when transiting to and from
the project site (see 50 CFR 216.18,
223.214, and 224.103(b)); not allow
lines to remain in the water, and not
throw trash or other debris overboard,
thereby reducing the potential for
marine mammal entanglement; follow
established transit routes and travel <10
knots while in the harassment zones;
follow the speed limit within Tongass
Narrows (7 knots for vessels over 23 ft
in length). If a whale’s course and speed
are such that it will likely cross in front
of a vessel that is underway, or
approach within 91 m (100 yards (yd))
of the vessel, and if maritime conditions
safely allow, the engine will be put in
neutral and the whale will be allowed
to pass beyond the vessel, except that
vessels will remain 460 m (500 yd) from
North Pacific right whales; if a
humpback whale comes within 10 m
(32.8 ft) of a vessel during construction,
the vessel will reduce speed to the
minimum level required to maintain
safe steerage and working conditions
until the humpback whale is at least 10
m (32.8 ft) away from the vessel; vessels
are prohibited from disrupting the
normal behavior or prior activity of a
whale by any other act or omission.
• ADOT must use soft start
techniques when impact pile driving.
Soft start requires contractors to provide
an initial set of three strikes at reduced
energy, followed by a 30-second waiting
period, then two subsequent reducedenergy strike sets. A soft start must be
implemented at the start of each day’s
impact pile driving and at any time
following cessation of impact pile
driving for a period of 30 minutes or
longer; and
• If take by Level B harassment
reaches the authorized limit for an
authorized species, pile installation will
be stopped as these species approach
the Level B harassment zone to avoid
additional take of them.
Further, on days when simultaneous
use of two hammers producing
continuous noise (two DTH hammers,
one DTH and one vibratory hammer, or
two vibratory hammers) is expected:
• When combinations of one DTH
hammer with a vibratory hammer or two
DTH hammers are used simultaneously,
each PSO of the two contractors will
have three PSOs working and the PSO
teams will work together to monitor the
entire area;
• One or more PSOs will be present
at each construction site during in-water
pile installation and removal so that
Level A harassment zones and
shutdown zones are monitored by a
dedicated PSO at all times.
• The ADOT environmental
coordinator for the project will
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implement coordination between or
among the PSO contractors. ADOT will
include in the contracts that PSOs must
coordinate, collaborate, and otherwise
work together to ensure compliance
with project permits and authorizations.
The following specific mitigation
measures will also apply to ADOT’s inwater construction activities:
Establishment of Level A Harassment
Zones and Shutdown Zones—For all
pile driving/removal and DTH activities,
ADOT will establish a shutdown zone
(Table 15). The purpose of a shutdown
zone is generally to define an area
within which shutdown of activity will
occur upon sighting of a marine
mammal (or in anticipation of an animal
entering the defined area). Shutdown
zones vary based on the activity type
and duration and marine mammal
hearing group (Table 15). For vibratory
installation and removal and impact
installation, shutdown zones will be
based on the Level A harassment
isopleth distances for each hearing
group.
ADOT anticipates that the daily
duration of DTH use may vary
significantly, with large differences in
maximum zones sizes possible
depending on the work planned for a
given day. Given this uncertainty and
concerns related to ESA-listed
humpback whales, ADOT will utilize a
tiered system to identify and monitor
the appropriate Level A harassment
zones and shutdown zones, based on
the maximum expected DTH duration.
At the start of any work involving DTH,
ADOT will first determine whether DTH
may occur at two sites concurrently or
just at one site. If DTH may occur at two
sites concurrently, then ADOT will
implement the Level A harassment
zones and shutdown zones associated
with simultaneous DTH use of the
relevant pile sizes (Table 13 and Table
15). If DTH may only occur at one site,
ADOT will then determine the
maximum duration of DTH possible that
day (according to the defined duration
intervals in Table 15), which will
determine the appropriate Level A
harassment isopleth for that day (Table
12 and Table 13). This Level A
harassment zone and associated
shutdown zone must be observed by
PSO(s) for the entire work day or until
it is determined that, given the duration
of activity for the day, the Level A
harassment isopleth cannot exceed the
next lower Level A harassment isopleth
size in Table 12.
Due to practicability concerns,
shutdown zones for some species during
some activities may be smaller than the
Level A harassment isopleths (Table 15).
The placement of PSOs during all pile
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driving, pile removal, and DTH
activities (described in detail in the
Monitoring and Reporting section) will
ensure that the entire shutdown zones
are visible during pile installation.
TABLE 15—SHUTDOWN ZONES AND LEVEL B HARASSMENT ISOPLETHS FOR EACH ACTIVITY
Activity
Shutdown distances
(m)
Minutes per
pile or
strikes per
pile
Pile size
(in)
LF
(humpback
whales)
LF
(minke
whales)
Vibratory Installation .................
30
24
20
60 min ........
60 min
60 min
Vibratory Removal ....................
24
60 min
DTH of Rock Sockets ...............
30
60 min ........
120 min ......
180 min ......
240 min ......
300 min ......
360 min ......
420 min ......
480 min ......
540 min ......
600 min ......
60 min ........
120 min ......
180 min ......
240 min ......
300 min ......
360 min ......
420 min ......
480 min ......
540 min ......
600 min ......
780
1,300
1,700
2,000
2,300
2,600
2,900
3,100
3,400
3,600
360
570
750
910
1,100
1,200
1,400
1,500
1,600
1,700
1,500
24
MF
HF
50
PW
Level B
harassment
isopleth
(m)
OW
20
30
50
60
70
90
100
130
20
30
30
40
40
50
50
60
60
60
1,500
6,310
5,412
500
200
500
200
40
50
70
80
90
100
13,594
100
20
30
30
40
50
50
60
60
70
70
DTH of Tension Anchor ............
8
120 min ......
240 min ......
90
130
90
130
20
100
160
50
70
20
Impact Installation .....................
30
24
20
50 strikes ....
50 strikes ....
50 strikes
100
60
100
60
20
120
70
60
30
20
2,154
1,000
TABLE 16—SHUTDOWN ZONES, BY HEARING GROUP FOR SIMULTANEOUS USE OF TWO DTH HAMMERS
Level A harassment isopleth
(m)
Duration
(minutes)
Activity combination
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LF
MF
HF
PW
OW
8-in pile, 8-in pile .....................................
60
120
180
240
90
130
170
210
20
100
160
200
250
50
70
100
110
20
8-in pile, 24-in pile ...................................
60
120
180
240
520
820
1,080
1,300
20
30
40
50
500
200
20
40
50
60
8-in pile, 30-in pile ...................................
60
120
180
240
1,110
1,770
2,310
2,800
40
70
90
100
50
70
90
110
24-in pile, 24-in pile .................................
60
120
180
240
570
910
1,190
1,440
20
32
42
60
30
40
50
60
24-in pile, 30-in ........................................
60
120
180
240
900
1,430
1,880
2,270
40
60
70
90
40
60
80
90
30-in pile, 30-in pile .................................
60
120
1,230
1,950
50
70
50
80
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TABLE 16—SHUTDOWN ZONES, BY HEARING GROUP FOR SIMULTANEOUS USE OF TWO DTH HAMMERS—Continued
Level A harassment isopleth
(m)
Duration
(minutes)
Activity combination
LF
180
240
ADOT also must abide by the terms
and conditions of the December 19,
2019 Biological Opinion and Incidental
Take Statement issued by NMFS
pursuant to section 7 of the Endangered
Species Act.
Based on our evaluation of the
applicant’s proposed measures, as well
as other measures considered by NMFS,
NMFS has determined that the required
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.
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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 project 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
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MF
2,550
3,090
HF
100
110
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).
• Mitigation and monitoring
effectiveness.
Visual Monitoring
Monitoring must be conducted by
qualified, NMFS-approved PSOs, in
accordance with the following:
• PSOs must be independent (i.e., not
construction personnel) and have no
other assigned tasks during monitoring
periods. At least one PSO must have
prior experience performing the duties
of a PSO during construction activity
pursuant to a NMFS-issued IHA. Other
PSOs may substitute other relevant
experience, education (degree in
biological science or related field), or
training for prior experience performing
the duties of a PSO during construction
activity pursuant to a NMFS-issued
IHA. Where a team of three or more
PSOs is required, a lead observer or
monitoring coordinator must be
designated. The lead observer must have
prior experience performing the duties
of a PSO during construction activity
pursuant to a NMFS-issued incidental
take authorization. PSOs must be
approved by NMFS prior to beginning
any activity subject to this IHA; and
• PSOs must record all observations
of marine mammals as described in the
Section 5 of the IHA and the Marine
Mammal Monitoring Plan, regardless of
distance from the pile being driven.
PSOs shall document any behavioral
reactions in concert with distance from
piles being driven or removed;
PSOs must have the following
additional qualifications:
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OW
100
120
• Ability to conduct field
observations and collect data according
to assigned protocols;
• Experience or training in the field
identification of marine mammals,
including the identification of
behaviors;
• Sufficient training, orientation, or
experience with the construction
operation to provide for personal safety
during observations;
• Writing skills sufficient to prepare a
report of observations including but not
limited to the number and species of
marine mammals observed; dates and
times when in-water construction
activities were conducted; dates, times,
and reason for implementation of
mitigation (or why mitigation was not
implemented when required); and
marine mammal behavior; and
• Ability to communicate orally, by
radio or in person, with project
personnel to provide real-time
information on marine mammals
observed in the area as necessary;
Additionally, as required by NMFS’
December 2019 Biological Opinion,
each PSO will be trained and provided
with reference materials to ensure
standardized and accurate observations
and data collection.
ADOT must employ three PSOs
during all pile driving and DTH. A
minimum of one PSO (the lead PSO)
must be assigned to the active pile
driving or DTH location to monitor the
shutdown zones and as much of the
Level B harassment zones as possible.
Two additional PSOs are also required,
though the observation points may vary
depending on the construction activity
and location of the piles. To select the
best observation locations, prior to start
of construction, the lead PSO will stand
at the construction site to monitor the
Level A harassment zones while two or
more PSOs travel in opposite directions
from the project site along Tongass
Narrows until they have reached the
edge of the appropriate Level B
harassment zone, where they will
identify suitable observation points
from which to observe. When needed,
an additional PSO will be stationed on
the north end of Revilla Island
observing to the northwest. See Figure
2–11 of ADOT’s Marine Mammal
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Monitoring and Mitigation Plan for a
map of planned PSO locations. If
visibility deteriorates so that the entire
width of Tongass Narrows at the
harassment zone boundary is not
visible, additional PSOs may be
positioned so that the entire width is
visible, or work will be halted until the
entire width is visible to ensure that any
humpback whales entering or within the
harassment zone are detected by PSOs.
When DTH use occurs, or
simultaneous use of one DTH with a
vibratory hammer or two DTH systems
occurs, creating Level B harassment
zones that exceed 13 km and 21 km,
respectively, and Level A harassment
zones that extend over 6 km, one
additional PSO will be stationed at the
northernmost land-based location at the
entrance to Tongass Narrows (at least
two PSOs total at that location, four
PSOs on duty across all PSO locations).
One of these PSO will focus on Tongass
Narrows, specifically watching for
marine mammals that could approach or
enter Tongass Narrows and the project
area. The second PSO will look out into
Clarence Strait, watching for marine
mammals that could swim through the
ensonified area. No additional PSOs
will be required at the southern-most
monitoring location because the Level B
harassment zones are truncated to the
southeast by islands, which prevent
propagation of sound in that direction
beyond the confines of Tongass
Narrows. Takes by Level B harassment
will be recorded by PSOs and
extrapolated based upon the number of
observed takes and the percentage of the
Level B harassment zone that was not
visible.
Each construction contractor
managing an active construction site
and on-going in-water pile installation
or removal will provide qualified,
independent PSOs for their specific
contract. The ADOT environmental
coordinator for the project will
implement coordination between or
among the PSO contractors. It will be a
required component of their contracts
that PSOs coordinate, collaborate, and
otherwise work together to ensure
compliance with project permits and
authorizations.
Reporting
A draft marine mammal monitoring
report will be submitted to NMFS
within 90 days after the completion of
pile driving and removal activities, or
60 days prior to a requested date of
issuance of any future IHAs for projects
at the same location, whichever comes
first. The report will include an overall
description of work completed, a
narrative regarding marine mammal
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sightings, and associated PSO data
sheets. Specifically, the report must
include:
• Dates and times (begin and end) of
all marine mammal monitoring;
• Construction activities occurring
during each daily observation period,
including the number and type of piles
driven or removed and by what method
(i.e., impact, vibratory or DTH) and the
total equipment duration for vibratory
removal or DTH for each pile or hole or
total number of strikes for each pile
(impact driving);
• PSO locations during marine
mammal monitoring;
• Environmental conditions during
monitoring periods (at beginning and
end of PSO shift and whenever
conditions change significantly),
including Beaufort sea state and any
other relevant weather conditions
including cloud cover, fog, sun glare,
and overall visibility to the horizon, and
estimated observable distance;
• Upon observation of a marine
mammal, the following information:
Name of PSO who sighted the animal(s)
and PSO location and activity at time of
sighting; Time of sighting; Identification
of the animal(s) (e.g., genus/species,
lowest possible taxonomic level, or
unidentified), PSO confidence in
identification, and the composition of
the group if there is a mix of species;
Distance and bearing of each marine
mammal observed relative to the pile
being driven for each sighting (if pile
driving was occurring at time of
sighting); Estimated number of animals
(min/max/best estimate); Estimated
number of animals by cohort (adults,
juveniles, neonates, group composition,
sex class, etc.); Animal’s closest point of
approach and estimated time spent
within the harassment zone; Description
of any marine mammal behavioral
observations (e.g., observed behaviors
such as feeding or traveling), including
an assessment of behavioral responses
thought to have resulted from the
activity (e.g., no response or changes in
behavioral state such as ceasing feeding,
changing direction, flushing, or
breaching);
• Number of marine mammals
detected within the harassment zones
and shutdown zones, by species;
• Table summarizing any incidents
resulting in take of ESA-listed species;
• Detailed information about any
implementation of any mitigation
triggered (e.g., shutdowns and delays), a
description of specific actions that
ensued, and resulting changes in
behavior of the animal(s), if any;
• Description of other human activity
within each monitoring period;
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• Description of any deviation from
initial proposal in pile numbers, pile
types, average driving times, etc.;
• Brief description of any
impediments to obtaining reliable
observations during construction
period;
• Description of any impediments to
complying with these mitigation
measures; and
• If visibility degrades to where the
PSO(s) cannot view the entire impact or
vibratory harassment zones, take of
humpback whales will be extrapolated
based on the estimated percentage of the
monitoring zone that remains visible
and the number of marine mammals
observed.
If no comments are received from
NMFS within 30 days, the draft final
report will constitute the final report. If
comments are received, a final report
addressing NMFS comments must be
submitted within 30 days after receipt of
comments.
Reporting Injured or Dead Marine
Mammals
In the event that personnel involved
in the construction activities discover
an injured or dead marine mammal, the
IHA-holder must immediately cease the
specified activities and report the
incident to the Office of Protected
Resources (OPR)
(PR.ITP.MonitoringReports@noaa.gov),
NMFS and to the Alaska Regional
Stranding Coordinator as soon as
feasible. If the death or injury was
clearly caused by the specified activity,
ADOT must immediately cease the
specified activities until NMFS is able
to review the circumstances of the
incident and determine what, if any,
additional measures are appropriate to
ensure compliance with the terms of the
IHA. The IHA-holder must not resume
their activities until notified by NMFS.
The report must include the following
information:
• Time, date, and location (latitude/
longitude) of the first discovery (and
updated location information if known
and applicable);
• Species identification (if known) or
description of the animal(s) involved;
• Condition of the animal(s)
(including carcass condition if the
animal is dead);
• Observed behaviors of the
animal(s), if alive;
• If available, photographs or video
footage of the animal(s); and
• General circumstances under which
the animal was discovered.
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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’ 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 species listed in Table 1
for which take could occur, given that
NMFS expects the anticipated effects of
the planned pile driving/removal and
DTH on different marine mammal
stocks to be similar in nature. Where
there are meaningful differences
between species or stocks, or groups of
species, in anticipated individual
responses to activities, impact of
expected take on the population due to
differences in population status, or
impacts on habitat, NMFS has identified
species-specific factors to inform the
analysis.
Pile driving and DTH activities
associated with the project, as outlined
previously, have the potential to disturb
or displace marine mammals.
Specifically, the specified activities may
result in take, in the form of Level B
harassment and, for some species Level
A harassment, from underwater sounds
generated by pile driving and DTH.
Potential takes could occur if marine
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mammals are present in zones
ensonified above the thresholds for
Level B harassment or Level A
harassment, identified above, while
activities are underway.
NMFS does not anticipate that serious
injury or mortality will occur as a result
of ADOT’s planned activity given the
nature of the activity, even in the
absence of required mitigation. Further,
no take by Level A harassment is
anticipated for Pacific white-sided
dolphin, killer whale, or humpback
whale, due to the likelihood of
occurrence and/or required mitigation
measures. As stated in the mitigation
section, ADOT will implement
shutdown zones that equal or exceed
many of the Level A harassment
isopleths shown in Table 12. Take by
Level A harassment is authorized for
some species (Steller sea lions, harbor
seals, harbor porpoises, Dall’s porpoises,
and minke whales) to account for the
potential that an animal could enter and
remain within the area between a Level
A harassment zone and the shutdown
zone for a duration long enough to be
taken by Level A harassment, and in
some cases, to account for the
possibility that an animal could enter a
shutdown zone without detection given
the various obstructions along the
shoreline, and remain in the Level A
harassment zone for a duration long
enough to be taken by Level A
harassment before being observed and a
shutdown occurring. Any take by Level
A harassment is expected to arise from,
at most, a small degree of PTS because
animals would need to be exposed to
higher levels and/or longer duration
than are expected to occur here in order
to incur any more than a small degree
of PTS. Additionally, and as noted
previously, some subset of the
individuals that are behaviorally
harassed could also simultaneously
incur some small degree of TTS for a
short duration of time. Because of the
small degree anticipated, though, any
PTS or TTS potentially incurred here is
not expected to adversely impact
individual fitness, let alone annual rates
of recruitment or survival.
For all species and stocks, take will
occur within a limited, confined area
(adjacent to the project site) of the
stock’s range. Take by Level A
harassment and Level B harassment will
be reduced to the level of least
practicable adverse impact through use
of mitigation measures described herein.
Further the amount of take authorized is
small when compared to stock
abundance.
Behavioral responses of marine
mammals to pile driving, pile removal,
and DTH at the sites in Tongass
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Narrows are expected to be mild, short
term, and temporary. Marine mammals
within the Level B harassment zones
may not show any visual cues they are
disturbed by activities or they could
become alert, avoid the area, leave the
area, or display other mild responses
that are not observable such as changes
in vocalization patterns. Given that pile
driving, pile removal, and DTH will
occur for only a portion of the project’s
duration and often on nonconsecutive
days, any harassment will be temporary.
Additionally, many of the species
present in Tongass Narrows or Clarence
Strait will only be present temporarily
based on seasonal patterns or during
transit between other habitats. These
temporarily present species will be
exposed to even smaller periods of
noise-generating activity, further
decreasing the impacts.
For all species except humpback
whales, there are no known Biologically
Important Areas (BIAs) near the project
zone that will be impacted by ADOT’s
planned activities. For humpback
whales, the whole of Southeast Alaska
is a seasonal BIA from spring through
late fall (Ferguson et al. 2015), however,
Tongass Narrows and Clarence Strait are
not important portions of this habitat
due to development and human
presence. Tongass Narrows is also a
small passageway and represents a very
small portion of the total available
habitat. Also, while southeast Alaska is
considered an important area for feeding
humpback whales between March and
May (Ellison et al. 2012), it is not
currently designated as critical habitat
for humpback whales (86 FR 21082;
April 21, 2021).
More generally, there are no known
calving or rookery grounds within the
project area, but anecdotal evidence
from local experts shows that marine
mammals are more prevalent in Tongass
Narrows and Clarence Strait during
spring and summer associated with
feeding on aggregations of fish, meaning
the area may play a role in foraging.
Because ADOT’s activities could occur
during any season, takes may occur
during important feeding times.
However, the project area represents a
small portion of available foraging
habitat and impacts on marine mammal
feeding for all species, including
humpback whales, should be minimal.
Any impacts on marine mammal prey
that occur during ADOT’s planned
activity will have, at most, short-term
effects on foraging of individual marine
mammals, and likely no effect on the
populations of marine mammals as a
whole. Indirect effects on marine
mammal prey during the construction
are expected to be minor, and these
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effects are unlikely to cause substantial
effects on marine mammals at the
individual level, with no expected effect
on annual rates of recruitment or
survival.
In addition, it is unlikely that minor
noise effects in a small, localized area of
habitat will have any effect on the
reproduction or survival of any
individuals, much less the stocks’
annual rates of recruitment or survival.
In combination, we believe that these
factors, as well as the available body of
evidence from other similar activities,
demonstrate that the potential effects of
the specified activities will have only
minor, short-term effects on individuals.
The specified activities are not expected
to impact rates of recruitment or
survival and will, therefore, not result in
population-level impacts.
In summary, and as described above,
the following factors primarily support
our 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 serious injury or mortality is
anticipated or authorized;
• Take by Level A harassment of
Pacific white-sided dolphin, killer
whale, and humpback whale is not
anticipated or authorized;
• ADOT will implement mitigation
measures including soft-starts for
impact pile driving and shutdown zones
to minimize the numbers of marine
mammals exposed to injurious levels of
sound, and to ensure that any take by
Level A harassment is, at most, a small
degree of PTS;
• The intensity of anticipated takes
by Level B harassment is relatively low
for all stocks and will not be of a
duration or intensity expected to result
in impacts on reproduction or survival;
• The only known area of specific
biological importance covers a broad
area of southeast Alaska for humpback
whales, and the project area is a very
small portion of that BIA. No other
known areas of particular biological
importance to any of the affected
species or stocks are impacted by the
activity, including ESA-designated
critical habitat;
• The project area represents a very
small portion of the available foraging
area for all potentially impacted marine
mammal species and stocks and
anticipated habitat impacts are minor;
and
• Monitoring reports from similar
work in Tongass Narrows have
documented little to no effect on
individuals of the same species
impacted by the specified activities.
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Based on the analysis contained
herein of the likely effects of the
specified activity on marine mammals
and their habitat, and taking into
consideration the implementation of the
required monitoring and mitigation
measures, NMFS finds that the total
marine mammal take from the planned
activity 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. When the
predicted number of individuals to be
taken is fewer than one third of the
species or stock abundance, the take is
considered to be of small numbers.
Additionally, other qualitative factors
may be considered in the analysis, such
as the temporal or spatial scale of the
activities.
The instances of take NMFS
authorized are below one third of the
estimated stock abundance for all stocks
(see Table 14). The number of animals
that we expect to authorize to be taken
from these stocks is considered small
relative to the relevant stocks’
abundances even if each estimated
taking occurred to a new individual,
which is an unlikely scenario. Some
individuals may return multiple times
in a day, but PSOs will count them as
separate takes if they cannot be
individually identified.
The Alaska stock of Dall’s porpoise
has no official NMFS abundance
estimate for this area, as the most recent
estimate is greater than eight years old.
The most recent estimate was 13,110
animals for just a portion of the stock’s
range. Therefore, the 227 authorized
takes of this stock clearly represent
small numbers of this stock.
Likewise, the Southeast Alaska stock
of harbor porpoise has no official NMFS
abundance estimate as the most recent
estimate is greater than 8 years old. The
most recent estimate was 11,146
animals (Muto et al. 2021) and it is
highly unlikely this number has
drastically declined. Therefore, the 32
authorized takes of this stock clearly
represent small numbers of this stock.
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There is no current or historical
estimate of the Alaska minke whale
stock, but there are known to be over
1,000 minke whales in the Gulf of
Alaska (Muto et al. 2018), so the 3
authorized takes clearly represent small
numbers of this stock. Additionally, the
range of the Alaska stock of minke
whales is extensive, stretching from the
Canadian Pacific coast to the Chukchi
Sea, and ADOT’s project area impacts a
small portion of this range.
Based on the analysis contained
herein of the planned activity (including
the required mitigation and monitoring
measures) and the anticipated take of
marine mammals, NMFS 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
In order to issue an IHA, NMFS must
find that the specified activity will not
have an ‘‘unmitigable adverse impact’’
on the subsistence uses of the affected
marine mammal species or stocks by
Alaska Natives. NMFS has defined
‘‘unmitigable adverse impact’’ in 50 CFR
216.103 as an impact resulting from the
specified activity: (1) That is likely to
reduce the availability of the species to
a level insufficient for a harvest to meet
subsistence needs by: (i) Causing the
marine mammals to abandon or avoid
hunting areas; (ii) Directly displacing
subsistence users; or (iii) Placing
physical barriers between the marine
mammals and the subsistence hunters;
and (2) That cannot be sufficiently
mitigated by other measures to increase
the availability of marine mammals to
allow subsistence needs to be met.
Harbor seals are the marine mammal
species most regularly harvested for
subsistence by households in Ketchikan
and Saxman (a community a few miles
south of Ketchikan, on the Tongass
Narrows). Eighty harbor seals were
harvested by Ketchikan residents in
2007, which ranked fourth among all
communities in Alaska that year for
harvest of harbor seals. Thirteen harbor
seals were harvested by Saxman
residents in 2007. In 2008, two Steller
sea lions were harvested by Ketchikanbased subsistence hunters, but this is
the only record of sea lion harvest by
residents of either Ketchikan or Saxman.
In 2012, the community of Ketchikan
had an estimated subsistence take of 22
harbor seals and 0 Steller sea lion (Wolf
et al. 2013). NMFS is not aware of more
recent data. Hunting usually occurs in
October and November (ADF&G 2009),
but there are also records of relatively
high harvest in May (Wolfe et al. 2013).
The Alaska Department of Fish and
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Game (ADF&G) has not recorded harvest
of cetaceans from Ketchikan or Saxman
(ADF&G 2018).
All project activities will take place
within the industrial area of Tongass
Narrows immediately adjacent to
Ketchikan where subsistence activities
do not generally occur. Both the harbor
seal and the Steller sea lion may be
temporarily displaced from the project
area. The project will also not have an
adverse impact on the availability of
marine mammals for subsistence use at
locations farther away, where these
construction activities are not expected
to take place. Some minor, short-term
harassment of the harbor seals could
occur, but given the information above,
we do not expect such harassment to
have effects on subsistence hunting
activities.
Based on the description of the
specified activity and the required
mitigation and monitoring measures,
NMFS has determined that there will
not be an unmitigable adverse impact on
subsistence uses from ADOT’s planned
activities.
jspears on DSK121TN23PROD with NOTICES1
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 evaluate our
proposed action (i.e., the issuance of an
IHA) and alternatives with respect to
potential impacts on the human
environment. This action is consistent
with categories of activities identified in
Categorical Exclusion B4 of the
Companion Manual for NAO 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 determined that this action
qualifies to be categorically excluded
from further NEPA review.
Endangered Species Act
Section 7(a)(2) of the Endangered
Species Act of 1973 (ESA: 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’ Office of Protected
Resources (OPR) consults internally
whenever we propose to authorize take
for endangered or threatened species, in
VerDate Sep<11>2014
18:27 Mar 17, 2022
Jkt 256001
this case with NMFS’ Alaska Regional
Office (AKRO).
NMFS OPR is proposing to authorize
take of the Central North Pacific stock
of humpback whales, of which a portion
belong to the Mexico DPS of humpback
whales, which are ESA-listed. On
February 6, 2019, NMFS AKRO
completed consultation with NMFS for
the Tongass Narrows Project and issued
a Biological Opinion. Reinitiation of
formal consultation was required to
analyze changes to the action that were
not considered in the February 2019
opinion (PCTS# AKR–2018–9806/ECO#
AKRO–2018–01287). The original
opinion considered the effects of only
one project component being
constructed at a time and did not
analyze potential effects of concurrent
pile driving that may cause effects to the
listed species that were not considered
in the original opinion; therefore,
reinitiation of formal consultation was
required. NMFS’ AKRO issued a revised
Biological Opinion to NMFS’ OPR on
December 19, 2019 that concluded that
issuance of IHAs to ADOT is not likely
to jeopardize the continued existence of
Mexico DPS humpback whales. The
effects of this Federal action were
adequately analyzed in NMFS’
Endangered Species Act (ESA) Section
7(a)(2) Biological Opinion for
Construction of the Tongass Narrows
Project (Gravina Access), revised
December 19, 2019, which concluded
that the take NMFS proposes to
authorize through this IHA would not
jeopardize the continued existence of
any endangered or threatened species or
destroy or adversely modify any
designated critical habitat. NMFS has
determined that issuance of this IHA
does not require reinitiation of the
December 2019 Biological Opinion.
Authorization
NMFS has issued an IHA to ADOT for
the potential harassment of small
numbers of eight marine mammal
species incidental to construction of
four facilities in the channel between
Gravina Island and Revillagigedo
(Revilla) Island in Ketchikan, Alaska,
that includes the previously explained
mitigation, monitoring and reporting
requirements.
Dated: March 11, 2022.
Kimberly Damon-Randall,
Director, Office of Protected Resources,
National Marine Fisheries Service.
[FR Doc. 2022–05561 Filed 3–17–22; 8:45 am]
BILLING CODE 3510–22–P
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DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric
Administration
[Docket ID No.: NOAA–NOS–2022–0033]
Deep Seabed Hard Minerals; Request
for Extension of Exploration Licenses;
Comments Request
Office for Coastal Management
(OCM), National Ocean Service (NOS),
National Oceanic and Atmospheric
Administration (NOAA), Department of
Commerce (DOC).
ACTION: Notice of receipt of application
to extend Deep Seabed Mineral
Exploration Licenses USA–1 and USA–
4; request for comments.
AGENCY:
NOS has received from the
Lockheed Martin Corporation
(‘‘Lockheed Martin’’ or ‘‘Licensee’’) a
request to extend to 2027 two deep
seabed hard mineral exploration
licenses issued pursuant to the Deep
Seabed Hard Mineral Resources Act
(DSHMRA). Lockheed Martin’s
extension request includes an updated
exploration plan for activities
conducted under the licenses. Lockheed
Martin’s request and accompanying
exploration plan are available for public
review and comment on whether the
Licensee has met the criteria for the
issuance of extensions specified in
DSHMRA.
DATES: Comments may be submitted on
or before May 17, 2022.
ADDRESSES: To access and review all
documents related to the extension
request under consideration, please use
https://www.regulations.gov by searching
the Docket ID number NOAA–NOS–
2022–0033. Comments submitted in
response to this notice should be
submitted electronically through the
Federal eRulemaking Portal at https://
www.regulations.gov by selecting the
Docket ID number.
FOR FURTHER INFORMATION CONTACT:
Kerry Kehoe, Federal Consistency
Specialist, NOAA Office of Coastal
Management, at kerry.kehoe@noaa.gov,
or at 240–560–8515.
SUPPLEMENTARY INFORMATION: NOAA has
received an application from Lockheed
Martin for a five-year extension of its
two Deep Seabed Hard Mineral
Exploration Licenses, USA–1 and USA–
4. Lockheed Martin’s application
includes a single revised exploration
plan for both licenses that sets forth the
activities to be conducted during the
extension.
DSHMRA exploration licenses USA–1
and USA–4 were issued in 1984 and
both are presently held by Lockheed
SUMMARY:
E:\FR\FM\18MRN1.SGM
18MRN1
]]>Agencies
[Federal Register Volume 87, Number 53 (Friday, March 18, 2022)]
[Notices]
[Pages 15387-15408]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2022-05561]
-----------------------------------------------------------------------
DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
[RTID 0648-XB799]
Takes of Marine Mammals Incidental to Specified Activities;
Taking Marine Mammals Incidental to Ferry Berth Improvements in Tongass
Narrows in Ketchikan, Alaska
AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and
Atmospheric Administration (NOAA), Commerce.
ACTION: Notice; issuance of an incidental harassment authorization.
-----------------------------------------------------------------------
SUMMARY: In accordance with the regulations implementing the Marine
Mammal Protection Act (MMPA) as amended, notification is hereby given
that NMFS has issued an incidental harassment authorization (IHA) to
the Alaska Department of Transportation and Public Facilities (ADOT) to
incidentally harass, by Level A harassment and Level B harassment only,
marine mammals during construction activities associated with
construction of four ferry berth facilities in Tongass Narrows in
Ketchikan, Alaska.
DATES: This authorization is effective from March 5, 2022 through March
4, 2023.
FOR FURTHER INFORMATION CONTACT: Leah Davis, 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
[[Page 15388]]
``mitigation''); and requirements pertaining to the mitigation,
monitoring and reporting of the takings are set forth. The definitions
of all applicable MMPA statutory terms cited above are included in the
relevant sections below.
Summary of Request
On August 19, 2021, NMFS received a request from the ADOT for an
IHA to take marine mammals incidental to the construction of two ferry
berth facilities in Tongass Narrows in Ketchikan, Alaska: The Gravina
Airport Ferry Layup Facility and the Gravina Freight Facility. On
December 17, 2021 we received a revised request that included
additional work components associated with the Revilla New Ferry Berth
and Upland Improvements and the New Gravina Island Shuttle Ferry Berth
and Related Terminal Improvements in the same region. The application
was deemed adequate and complete on January 4, 2022. ADOT's request is
for take of a small number of eight species of marine mammals, by Level
B harassment and Level A harassment. Of those eight species, five
(Steller sea lion (Eumetopias jubatus), harbor seal (Phoca vitulina
richardii), harbor porpoise (Phocoena phocoena), Dall's porpoise
(Phocoenoides dalli) and minke whale (Balaenoptera acutorostrata)) may
also be taken by Level A harassment. Neither ADOT nor NMFS expects
serious injury or mortality to result from this activity and,
therefore, an IHA is appropriate.
NMFS previously issued two consecutive IHAs and a Renewal IHA to
ADOT for this work (85 FR 673, January 7, 2020; 86 FR 23938, May 05,
2021). ADOT complied with all the requirements (e.g., mitigation,
monitoring, and reporting) of the previous IHAs and information
regarding their monitoring results may be found in the Description of
Marine Mammals in the Area of Specified Activities and Marine Mammal
Occurrence and Take Calculation and Estimation sections. An IHA for the
first phase of construction of the Ketchikan-Gravina Access Project was
issued to ADOT on December 20, 2019 (85 FR 673, January 7, 2020).
Complete construction of two of those components, the Revilla New Ferry
Berth and Upland Improvements and Gravina Island Shuttle Ferry Berth
Facility/Related Terminal Improvements, did not occur within the
timeframe authorized by the Phase 1 IHA and will not be finished before
the expiration of the subsequent one-year renewal (86 FR 23938, May 05,
2021). Therefore, ADOT requested a new IHA for incidental take
associated with the continued marine construction of these facilities.
Description of the Specified Activity
ADOT is making improvements to existing ferry berths and
constructing new ferry berths on Gravina Island and Revillagigedo
(Revilla) Island in Tongass Narrows, near Ketchikan in southeast Alaska
(Figure 1 of proposed IHA; 87 FR 5980; February 2, 2022). These ferry
facilities provide the only public access between the city of
Ketchikan, AK on Revilla Island, and the Ketchikan International
Airport on Gravina Island. The project's planned activities that have
the potential to take marine mammals, by Level A harassment and Level B
harassment, include vibratory and impact pile driving, down-the-hole
(DTH) operations for pile installation (rock socketing of piles and
tension anchors to secure piles), and vibratory pile removal. The
marine construction associated with the activities is planned to occur
over 91 non-consecutive days over one year beginning March 2022.
A detailed description of the planned construction project is
provided in the Federal Register notice for the proposed IHA (87 FR
5980; February 2, 2022). Since that time, no changes have been made to
the planned activities. Therefore, a detailed description is not
provided here. Please refer to that Federal Register notice for the
description of the specific activity.
Comments and Responses
A notice of NMFS' proposal to issue an IHA to ADOT was published in
the Federal Register on February 2, 2022 (87 FR 5980). That notice
described, in detail, ADOT's activity, the marine mammal species that
may be affected by the activity, and the anticipated effects on marine
mammals. During the 30-day public comment period, NMFS did not receive
any public comments.
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' 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' website (https://www.fisheries.noaa .gov/find-species).
Table 1 lists all species or stocks for which take is expected and
proposed to be authorized for this specified activity, and summarizes
information related to the population or stock, including regulatory
status under the MMPA and Endangered Species Act (ESA) and potential
biological removal (PBR), where known. For taxonomy, we follow
Committee on Taxonomy (2021). 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'
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' 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' U.S. Alaska SARs (e.g., Muto et al. 2021). All values presented
in Table 1 are the most recent available at the time of publication and
are available in the draft 2021 SARs (Muto et al. 2021; available
online at: https://www.fisheries.noaa.gov/national/marine-mammal-
protection/draft-marine-mammal-stock-assessment-reports).
[[Page 15389]]
Table 1--Marine Mammal Species or Stocks for Which Take is Expected and Authorized
--------------------------------------------------------------------------------------------------------------------------------------------------------
Stock abundance Nbest,
ESA/MMPA status; (CV; Nmin; most recent Annual M/
Common name Scientific name MMPA stock strategic (Y/N) abundance survey) \2\ PBR SI \3\
\1\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Order Cetartiodactyla--Cetacea--Superfamily Mysticeti (baleen whales)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Balaenidae:
Humpback whale.................. Megaptera novaeangliae. Central North Pacific.. E, D, Y 10,103 (0.3; 7,890; 83 26
2006).
Minke whale..................... Balaenoptera Alaska................. -, N N.A. (See SAR; N.A.; UND 0
acutorostrata. see SAR).
--------------------------------------------------------------------------------------------------------------------------------------------------------
Order Cetartiodactyla--Cetacea--Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Delphinidae:
Killer whale.................... Orcinus orca........... Alaska Resident........ -, N 2,347 (N.A.; 2,347; 24 1
2012).
West Coast Transient... -, N 349 (N.A, 349; 2018).. 3.5 *0.4
Northern Resident...... -, N 302 (N.A.; 302; 2018.. 2.2 0.2
Pacific white-sided dolphin..... Lagenorhynchus North Pacific.......... -,-; N 26,880 (N.A.; N.A.; UND 0
obliquidens. 1990).
Family Phocoenidae:
Harbor porpoise................. Phocoena phocoena...... Southeast Alaska....... -, Y See SAR (see SAR; see See SAR 34
SAR; 2012).
Dall's porpoise................. Phocoenoides dalli..... Alaska................. -, N See SAR (see SAR; see See SAR 37
SAR; 2015).
--------------------------------------------------------------------------------------------------------------------------------------------------------
Order Carnivora--Superfamily Pinnipedia
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Otariidae (eared seals and
sea lions):
Steller sea lion................ Eumetopias jubatus..... Eastern U.S............ -,-, N 43,201 (see SAR; 2,592 112
43,201; 2017).
Family Phocidae (earless seals):
Harbor seal..................... Phoca vitulina Clarence Strait........ -, N 27,659 (See SAE; 746 40
richardii. 24,854; 2015).
--------------------------------------------------------------------------------------------------------------------------------------------------------
\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-
assessments. CV is coefficient of variation; Nmin is the minimum estimate of stock abundance. In some cases, CV is not applicable (N.A.).
\3\ These values, found in NMFS' SARs, represent annual levels of human-caused mortality plus serious injury (M/SI) from all sources combined (e.g.,
commercial fisheries, ship strike). Annual M/SI often cannot be determined precisely and is in some cases presented as a minimum value or range. A CV
associated with estimated mortality due to commercial fisheries is presented in some cases.
All species that could potentially occur in the project area are
included in Table 3-1 of ADOT's IHA application. However, the spatial
occurrence of gray whale and fin whale is such that take is not
expected to occur, and they are not discussed further beyond the
explanation provided here. Gray whales have not been reported by any
local experts or recorded in monitoring reports and it would be
extremely unlikely for a gray whale to enter Tongass Narrows or the
small portions of Revillagigedo Channel this project will impact.
Similarly for fin whale, sightings have not been reported and it would
be unlikely for a fin whale to enter the project area as they are
generally associated with deeper, more offshore waters. The eight
species (with 10 managed stocks) in Table 1 temporally and spatially
co-occur with the activity to the degree that take is reasonably likely
to occur, and we have authorized it.
A detailed description of the of the species likely to be affected
by ADOT's project, including brief introductions to the species and
relevant stocks as well as available information regarding population
trends and threats, and information regarding local occurrence, were
provided in the Federal Register notice for the proposed IHA (87 FR
5980; February 2, 2022); since that time, we are not aware of any
changes in the status of these species and stocks; therefore, detailed
descriptions are not provided here. Please refer to that Federal
Register notice for these descriptions. Please also refer to NMFS'
website (https://www.fisheries.noaa .gov/find-species) for generalized
species accounts.
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 2.
[[Page 15390]]
Table 2--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, 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.
Eight marine mammal species (six cetacean and two pinniped (one otariid
and one phocid) species) have the reasonable potential to co-occur with
the planned activities. Please refer to Table 1. Of the cetacean
species that may be present, two are classified as low-frequency
cetaceans (i.e., all mysticete species), two are classified as mid-
frequency cetaceans (i.e., all delphinid and ziphiid species and the
sperm whale), and two are classified as high-frequency cetaceans (i.e.,
harbor porpoise, Dall's porpoise and Kogia spp.).
Potential Effects of Specified Activities on Marine Mammals and Their
Habitat
The effects of underwater noise from the ADOT's activities have the
potential to result in take of marine mammals by Level B harassment and
Level A harassment in the vicinity of the survey area. The notice of
proposed IHA (87 FR 5980; February 2, 2022) included a discussion of
the effects of anthropogenic noise on marine mammals and the potential
effects of underwater noise from ADOT's construction activities on
marine mammals and their habitat. That information and analysis is
incorporated by reference into this final IHA and is not repeated here;
please refer to the notice of the proposed IHA (87 FR 5980; February 2,
2022).
The Estimated Take section 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 section, and
the Mitigation Measures 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. We also provided
additional description of sound sources in our notice of proposed IHA
(87 FR 5980; February 2, 2022).
Estimated Take
This section provides an estimate of the number of incidental takes
authorized 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 will primarily be by Level B harassment, as use of
the acoustic sources (i.e., impact and vibratory pile driving and DTH)
have the potential to result in disruption of behavioral patterns for
individual marine mammals. There is also some potential for auditory
injury (Level A harassment) to result, primarily for mysticetes, high
frequency species and phocids because predicted auditory injury zones
are larger than for mid-frequency species and otariids. Auditory injury
is unlikely to occur to mid-frequency species and otariids. The
required mitigation and monitoring measures are expected to minimize
the severity of such taking to the extent practicable.
As described previously, no mortality is anticipated or 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 take estimate.
Acoustic Thresholds
NMFS recommends the use of 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
[[Page 15391]]
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 harassed in a manner we consider Level B harassment when
exposed to underwater anthropogenic noise above received levels of 120
dB re 1 microPascal ([mu]Pa) (root mean square (rms)) for continuous
(e.g., vibratory pile-driving, DTH) and above 160 dB re 1 [mu]Pa (rms)
for non-explosive impulsive (e.g., seismic airguns) or intermittent
(e.g., scientific sonar) sources. This take estimation includes
disruption of behavioral patterns resulting directly in response to
noise exposure (e.g., avoidance), as well as that resulting indirectly
from associated impacts such as TTS or masking. ADOT's planned activity
includes the use of continuous (vibratory pile driving/removal and DTH)
and impulsive (impact pile driving and DTH) sources, and therefore both
the 120 and 160 dB re 1 [mu]Pa (rms) thresholds are 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). ADOT's planned activity includes the use
of impulsive (impact pile driving and DTH) and non-impulsive (vibratory
pile driving/removal and DTH) sources.
These thresholds are provided in Table 3 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
https://www.fisheries.noaa.gov/national/marine-mammal-protection/
marine-mammal-acoustic-technical-guidance.
Table 3--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: Lpk,flat: 219 dB; Cell 2: LE,LF,24h: 199 dB.
LE,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.
----------------------------------------------------------------------------------------------------------------
* Dual metric acoustic thresholds for impulsive sounds: Use whichever results in the largest isopleth for
calculating PTS onset. If a non-impulsive sound has the potential of exceeding the peak sound pressure level
thresholds associated with impulsive sounds, these thresholds should also be considered.
Note: Peak sound pressure (Lpk) has a reference value of 1 [micro]Pa, and cumulative sound exposure level (LE)
has a reference value of 1[micro]Pa\2\s. In this Table, thresholds are abbreviated to reflect American
National Standards Institute standards (ANSI 2013). However, peak sound pressure is defined by ANSI as
incorporating frequency weighting, which is not the intent for this Technical Guidance. Hence, the subscript
``flat'' is being included to indicate peak sound pressure should be flat weighted or unweighted within the
generalized hearing range. The subscript associated with cumulative sound exposure level thresholds indicates
the designated marine mammal auditory weighting function (LF, MF, and HF cetaceans, and PW and OW pinnipeds)
and that the recommended accumulation period is 24 hours. The cumulative sound exposure level thresholds could
be exceeded in a multitude of ways (i.e., varying exposure levels and durations, duty cycle). When possible,
it is valuable for action proponents to indicate the conditions under which these acoustic thresholds will be
exceeded.
Ensonified Area
Here, we describe operational and environmental parameters of the
activity that will feed into identifying the area ensonified above the
acoustic thresholds, which include source levels and transmission loss
coefficient.
The sound field in the project area is the existing background
noise plus additional construction noise from the project. Marine
mammals are expected to be affected via sound generated by the primary
components of the project (i.e., impact pile driving, vibratory pile
driving, vibratory pile removal, and DTH).
In order to calculate distances to the Level A harassment and Level
B harassment sound thresholds for the methods and piles being used in
this project, NMFS used acoustic monitoring data from other locations
to develop source levels for the various pile types, sizes and methods
(Table 4). Note that piles of differing sizes have different sound
source levels (SSLs).
Empirical data from recent ADOT sound source verification (SSV)
studies at Ketchikan were used to estimate SSLs for vibratory and
impact driving of 30-inch steel pipe piles (Denes et al. 2016). Data
from Ketchikan was used because of its proximity to this project in
Tongass Narrows. However, the use of data from Alaska sites was not
appropriate in all instances. Details are described below.
For vibratory driving of 24-inch steel piles, data from a Navy pile
driving project in the Puget Sound, WA was reviewed (Navy 2015). From
this review, ADOT determined the Navy's suggested source value of 161
decibels (dB) root mean squared (rms) was an appropriate proxy source
value, and NMFS concurs. Because the source value of smaller piles of
the same general type (steel in this case) are not expected to exceed a
larger pile, the same 161 dB rms source value was used for 20-inch
steel piles. This assumption conforms with source values presented in
Navy (2015) for a project using 16-inch steel piles at Naval Base
Kitsap in Bangor, WA.
ADOT used source values of 177 dB sound exposure level (SEL) and
190 dB rms for impact driving of 24-inch and 20-inch steel piles. These
values were determined based on summary values presented in Caltrans
(2015) for impact driving of 24-inch steel piles. NMFS concurs that the
same source value was an acceptable proxy for impact driving of 20-inch
steel piles.
Sound pressure levels in the water column resulting from DTH are
not well studied. Because DTH hole creation includes both impulsive and
continuous components, NMFS guidance currently recommends that it be
treated as a continuous sound for Level B calculations and as an
impulsive sound for Level A calculations (Table 10). In the absence of
data specific to different hole sizes, current NMFS guidance
[[Page 15392]]
recommends that calculation of Level B zones for DTH use the same
continuous SSL of 167 dB SEL for all hole sizes (Heyvaert and Reyff
2021). Recommended SSLs for 30-inch and 24-inch holes as well as 8-inch
holes for tension anchors and micropiles for use in the calculation of
Level A harassment thresholds are provided by current NMFS guidance and
in Table 4.
Table 4--Estimates of Mean Underwater Sound Levels Generated During Vibratory and Impact Pile Installation, DTH,
and Vibratory Pile Removal
----------------------------------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------------------------------
Method and pile type SSL at 10 m Literature source
----------------------------------------------------------------------------------------------------------------
Vibratory hammer.............. dB rms
----------------------------------------------------------------------------------------------------------------
30-inch steel piles........... 162 Denes et al. 2016.
----------------------------------------------------------------------------------------------------------------
24-inch steel piles........... 161 Navy 2015.
----------------------------------------------------------------------------------------------------------------
20-inch steel piles........... 161 Navy 2015.
----------------------------------------------------------------------------------------------------------------
DTH of rock sockets and dB rms ......................
tension anchors.
----------------------------------------------------------------------------------------------------------------
All pile diameters............ 167 Heyvaert and Reyff
2021.
----------------------------------------------------------------------------------------------------------------
DTH of rock sockets and dB SELss dB peak ......................
tension anchors.
----------------------------------------------------------------------------------------------------------------
30-inch rock socket........... 164 194 Reyff and Heyvaert
2019; Reyff 2020;
Denes et al. 2016.
----------------------------------------------------------------------------------------------------------------
24-inch rock socket........... 159 184 Heyvaert and Reyff
2021.
----------------------------------------------------------------------------------------------------------------
8-inch tension anchor/ 144 170 Reyff 2020.
micropile.
----------------------------------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------------------------------
Impact Hammer dB rms dB SEL dB peak
----------------------------------------------------------------------------------------------------------------
30-inch steel piles........... 195 181 209 Denes et al. 2016.
----------------------------------------------------------------------------------------------------------------
24-inch steel piles........... 190 177 203 Caltrans 2015.
----------------------------------------------------------------------------------------------------------------
20-inch steel piles........... 190 177 202 Caltrans 2015.
----------------------------------------------------------------------------------------------------------------
Note: It is assumed that noise levels during pile installation and removal are similar. SEL = sound exposure
level; dB peak = peak sound level; rms = root mean square.
Simultaneous use of two impact, vibratory, or DTH hammers, or any
combination of those equipment, could occur. Such occurrences are
anticipated to be infrequent, will be for short durations on any given
day, and ADOT anticipates that no more than two hammers will be
operated concurrently. Simultaneous use of two hammers or DTH systems
could occur at the same project site, or at two different, but nearby
project sites. Simultaneous use of hammers could result in increased
SPLs and harassment zone sizes given the proximity of the component
driving sites and the physical rules of decibel addition. ADOT
anticipates that concurrent use of two hammers producing continuous
noise could occur on 44 days, which is half the anticipated number of
days of construction (91 days) and represents complete overlap between
the two contracts and/or represents use of two hammers by a single
contractor. Although it is unlikely that overlap will be complete, ADOT
anticipates, and NMFS concurs, this scenario represents the potential
worst case scenario, given that a more accurate estimate is not
possible, and concurrent operation of hammers will be incidental. Given
that the use of more than one hammer for pile installation on the same
day (whether simultaneous or not) will increase the number of piles
installed per day, this is anticipated to result in a reduction of the
total number of days of pile installation. Table 5 shows how potential
scenarios would reduce the total number of pile driving days and weeks.
However, as described in the Marine Mammal Occurrence and Take
Calculation and Estimation section below, ADOT has conservatively
calculated take with the assumption that pile driving will occur on all
91 days.
Table 5--Calculated Reduction of Pile Driving Days Based on Percentage of Project Days With Two Hammers in Use
----------------------------------------------------------------------------------------------------------------
Days of work
Days of completed Remaining days Total number
Percent overlap overlap during overlap of work with of days of Weeks of work
(2 hammers) single hammer work
----------------------------------------------------------------------------------------------------------------
0............................... 0.0 0.0 91.0 91.0 15.2
10.............................. 9.1 18.2 72.8 81.9 13.7
20.............................. 18.2 36.4 54.6 72.8 12.1
30.............................. 27.3 54.6 36.4 63.7 10.6
[[Page 15393]]
40.............................. 36.4 72.8 18.2 54.6 9.1
50.............................. 45.5 91.0 0.0 45.5 7.6
----------------------------------------------------------------------------------------------------------------
NMFS (2018b) handles overlapping sound fields created by the use of
more than one hammer differently for impulsive (impact hammer and Level
A harassment zones for drilling with a DTH hammer) and continuous sound
sources (vibratory hammer and Level B harassment zones for drilling
with a DTH hammer; Table 6) and differently for impulsive sources with
rapid impulse rates of multiple strikes per second (DTH) and slow
impulse rates (impact hammering) (NMFS 2021). It is unlikely that the
two impact hammers will strike at the same instant, and therefore, the
SPLs will not be adjusted regardless of the distance between impact
hammers. In this case, each impact hammer will be considered to have
its own independent Level A harassment and Level B harassment zones.
When two DTH hammers operate simultaneously their continuous sound
components overlap completely in time. When the Level B isopleth of one
DTH sound source encompasses the isopleth of another DTH sound source,
the sources are considered additive and combined using the following
rules (Table 7). The method described below was based on one created by
Washington State Department of Transportation (WSDOT) and has been
updated and modified by NMFS (WSDOT 2020). For addition of two
simultaneous DTH hammers, the difference between the two SSLs is
calculated, and if that difference is between 0 and 1 dB, 3 dB are
added to the higher SSL; if difference is between 2 or 3 dB, 2 dB are
added to the highest SSL; if the difference is between 4 to 9 dB, 1 dB
is added to the highest SSL; and with differences of 10 or more
decibels, there is no addition.
When two continuous noise sources, such as vibratory hammers, have
overlapping sound fields, there is potential for higher sound levels
than for non-overlapping sources.
When two or more vibratory hammers are used simultaneously, and the
isopleth of one sound source encompasses the isopleth of another sound
source, the sources are considered additive and source levels are
combined using the rules in Table 6, similar to that described above
for DTH.
Table 6--Rules for Combining Sound Source Levels Generated During Pile Installation
--------------------------------------------------------------------------------------------------------------------------------------------------------
Hammer types Difference in SSL Level A zones Level B zones
--------------------------------------------------------------------------------------------------------------------------------------------------------
Vibratory, Impact............. Any...................... Use impact zones.............................. Use largest zone.
Impact, Impact................ Any...................... Use zones for each pile size and number of Use zone for each pile size.
strikes.
Vibratory, Vibratory or DTH, 0 or 1 dB................ Add 3 dB to the higher source level........... Add 3 dB to the higher source level
DTH. 2 or 3 dB................ Add 2 dB to the higher source level........... Add 2 dB to the higher source level.
4 to 9 dB................ Add 1 dB to the higher source level........... Add 1 dB to the higher source level.
10 dB or more............ Add 0 dB to the higher source level........... Add 0 dB to the higher source level.
--------------------------------------------------------------------------------------------------------------------------------------------------------
During pile driving, it is common for pile installation to start
and stop multiple times as each pile is adjusted and its progress is
measured and documented, though as stated above, for short durations,
it is anticipated that multiple hammers could be in use simultaneously.
Following an approach modified from WSDOT in their Biological
Assessment manual (WSDOT 2020) and described in Table 7, decibel
addition calculations were carried out for possible combinations of
pile driving and DTH throughout the project area. The source levels
included in Table 7 are used to estimate the Level A harassment zones
and the Level B harassment zones.
Table 7--Combined SSLs (dB at 10 m) Generated During Pile Installation and Removal for Combinations of Two Pieces of Equipment: Impact Hammer, Vibratory
Hammer, and Down-the-Hole Drill
--------------------------------------------------------------------------------------------------------------------------------------------------------
--------------------------------------------------------------------------------------------------------------------------------------------------------
Method
Vibratory (RMS)
DTH (RMS)
DTH (SEL)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Pile diameter 20 24 30 8 24 30 8 24 30
--------------------------------------------------------------------------------------------------------------------------------------------------------
SSL 161 161 162 167 167 167 144 159 164
Vibratory (RMS)................ 20 161 164 164 165 168 168 168 ......... ......... .........
24 161 164 164 165 168 168 168 ......... ......... .........
30 162 165 165 165 168 168 168 ......... ......... .........
DTH (RMS)...................... 8 167 168 168 168 170 170 170 ......... ......... .........
24 167 168 168 168 170 170 170 ......... ......... .........
30 167 168 168 168 170 170 170 ......... ......... .........
DTH (SEL)...................... 8 144 ......... ......... ......... ......... ......... ......... 147 159 164
24 159 ......... ......... ......... ......... ......... ......... 159 162 165
30 164 ......... ......... ......... ......... ......... ......... 164 165 167
--------------------------------------------------------------------------------------------------------------------------------------------------------
[[Page 15394]]
No addition is warranted for impact pile driving in combination
with vibratory or impact pile driving or DTH (NMFS 2021).
Level B Harassment Zones
Transmission loss (TL) is the decrease in acoustic intensity as an
acoustic pressure wave propagates out from a source. TL parameters vary
with frequency, temperature, sea conditions, current, source and
receiver depth, water depth, water chemistry, and bottom composition
and topography. The general formula for underwater TL is:
TL = B * Log10 (R1/R2),
Where:
TL = transmission loss in dB
B = transmission loss coefficient; for practical spreading equals 15
R1 = the distance of the modeled SPL from the driven pile, and
R2 = the distance from the driven pile of the initial measurement
The recommended TL coefficient for most nearshore environments is
the practical spreading value of 15. This value results in an expected
propagation environment that will lie between spherical and cylindrical
spreading loss conditions, which is the most appropriate assumption for
ADOT's planned activity in the absence of specific modelling.
All Level B harassment isopleths are reported in Table 8 and Table
9 below. It should be noted that based on the geography of Tongass
Narrows and the surrounding islands, sound will not reach the full
distance of the Level B harassment isopleth in most directions.
Generally, due to interaction with land, only a thin slice of the
possible area is ensonified to the full distance of the Level B
harassment isopleth.
The size of the Level B harassment zone during concurrent operation
of two vibratory or DTH hammers will depend on the combination of sound
sources and the decibel addition of two hammers producing continuous
noise. Table 8 shows the distances to Level B harassment isopleths
during simultaneous hammering from two sources, based on the combined
SSL. Because the calculated Level B harassment isopleths for two
sources are dependent upon the combined SSL, the Level B harassment
zone for each combined sound source level included in Table 8 is
consistent, regardless of the equipment combination. Please refer to
Table 7 to determine which sound sources apply to each combined SSL.
As noted previously, pile installation often involves numerous
stops and starts of the hammer for each pile. Therefore, decibel
addition is applied only when the adjacent continuous sound sources
experience overlapping sound fields, which generally requires close
proximity of driving locations.
Table 8--Level B Harassment Isopleths for Multiple Vibratory Hammer
Additions
------------------------------------------------------------------------
Level B
harassment
Combined SSL (dB) isopleth
(m) \a\
------------------------------------------------------------------------
164........................................................ 8,577
165........................................................ 10,000
166........................................................ 11,659
167........................................................ 13,594
168........................................................ 15,849
169........................................................ 18,478
170........................................................ 21,544
------------------------------------------------------------------------
\a\ These larger zones are truncated to the southeast by islands, which
prevent propagation of sound in that direction beyond the confines of
Tongass Narrows. To the northwest of Tongass Narrows, combined sound
levels that exceed 167 dB rms extend into Clarence Strait before
attenuating to sound levels that are anticipated to be below 120 dB
rms.
Table 9--Level B Harassment Isopleths for Single Hammer Use by Activity
and Pile Size
------------------------------------------------------------------------
Level B
harassment
Activity Pile diameter isopleth
(m)
------------------------------------------------------------------------
Vibratory Installation............. 30-inch............... 6,310
24-inch............... 5,412
20-inch...............
Vibratory Removal.................. 24-inch...............
DTH Rock Sockets................... 30-inch............... 13,594
24-inch...............
DTH Tension Anchor/Micropile....... 8-inch................
Impact Installation................ 30-inch............... 2,154
24-inch............... 1,000
20-inch............... 1,000
------------------------------------------------------------------------
Level A Harassment Zones
When the NMFS Technical Guidance (2016) was published, in
recognition of the fact that ensonified area/volume could be more
technically challenging to predict because of the duration component in
the new thresholds, we developed a User Spreadsheet that includes tools
to help predict a simple isopleth that can be used in conjunction with
marine mammal density or occurrence to help predict takes. We note that
because of some of the assumptions included in the methods used for
these tools, we anticipate that isopleths produced are typically going
to be overestimates of some degree, which may result in some degree of
overestimate of takes by Level A harassment. However, these tools offer
the best way to predict appropriate isopleths when more sophisticated
3D modeling methods are not available, and NMFS continues to develop
ways to quantitatively refine these tools, and will qualitatively
address the output where appropriate. For stationary sources such as
pile driving or removal and DTH using any of the methods discussed
above, NMFS' User Spreadsheet predicts the closest distance at which,
if a marine mammal remained at that distance the whole duration of the
activity, it will incur PTS. Inputs used in the User Spreadsheet are
reported in Table 10 and Table 11, and the resulting isopleths are
reported below in Table 12 and Table 13. Pile installation and removal
can occur at variable rates, from a few minutes one day to many hours
the next. ADOT anticipates that one permanent pile will be installed
per day on 27 non-consecutive days, two temporary piles will be
installed per day on 10 non-consecutive days, and two temporary piles
will be removed per day on 10 days.
[[Page 15395]]
Table 10--NMFS User Spreadsheet Inputs For Single Hammer Use
--------------------------------------------------------------------------------------------------------------------------------------------------------
Vibratory
Vibratory pile driver Vibratory Impact pile Impact pile Impact pile
pile driver (installation pile driver DTH rock DTH rock DTH tension driver (30- driver (24- driver (20-
Equipment type (installation and removal (installation sockets (30- sockets (24- anchor (8- inch steel inch steel inch steel
of 30-inch of 24-inch of 20-inch inch) inch) inch) piles) piles) piles)
steel piles) steel piles) steel piles)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Spreadsheet tab used (A.1) (A.1) (A.1) (E.2) (E.2) (E.2) (E.1) (E.1) (E.1)
vibratory vibratory vibratory DTH pile DTH pile DTH pile impact pile impact pile impact pile
pile driving pile driving pile driving driving driving driving driving driving driving
--------------------------------------------------------------------------------------------------------------------------------------------------------
Weighting Factor Adjustment 2.5 2.5 2.5 2 2 2 2 2 2
(kHz).......................
SSL.......................... \a\ 162 \a\ 161 \a\ 161 \b\ 164 \b\ 159 \b\ 144 \b\ 181 \b\ 177 \b\ 177
Activity duration (hours) 1 1 1 1-10 1-10 2-4 ........... ........... ...........
within 24 hours.............
Number of piles per day...... 1 1 1 1 1 1 1 1 1
Strike rate strikes per ............. ............. ............. 15 15 25.83 ........... ........... ...........
second......................
Number of strikes per pile... ............. ............. ............. ........... ........... ........... 50 50 50
--------------------------------------------------------------------------------------------------------------------------------------------------------
Notes: Propagation loss coefficient in all cases is 15. Duration estimates for DTH are based on assumption of multiple rock sockets and tension anchors
being installed each day, with the maximum duration time for installation per day predicted to be 10 hours for rock socket DTH and 4 hours for tension
anchor DTH. For specifics regarding the number of strikes and number of piles that will be used in a given situation, please refer to Table 1 in the
notice of proposed IHA (87 FR 5980; February 2, 2022).
\a\ dB rms at 10m.
\b\ dB SEL at 10m.
Regarding implications for Level A harassment zones when two
vibratory hammers are operating concurrently, given the small size of
the estimated Level A harassment isopleths for all hearing groups
during vibratory pile driving, the zones of any two hammers are not
expected to overlap. Therefore, compounding effects of multiple
vibratory hammers operating concurrently are not anticipated, and NMFS
has treated each source independently.
Regarding implications for Level A harassment zones when one
vibratory hammer and one DTH hammer are operating concurrently,
combining isopleths for these sources is difficult for a variety of
reasons. First, vibratory pile driving relies upon non-impulsive PTS
thresholds, while DTH/rock hammers use impulsive thresholds. Second,
vibratory pile driving account for the duration to drive a pile, while
DTH account for strikes per pile. Thus, it is difficult to measure
sound on the same scale and combine isopleths from these impulsive and
non-impulsive, continuous sources. Therefore, NMFS has treated each
source independently at this time.
Regarding the operation of two DTH hammers concurrently, since DTH
hammers are capable of multiple strikes per second, there is potential
for multiple DTH/rock hammer sources' isopleths to overlap in space and
time (a higher strike rate indicates a greater potential for overlap).
Therefore, NMFS has calculated distances to Level A harassment
isopleths, by hearing group for simultaneous use of two DTH hammers
(Table 13), using NMFS' User Spreadsheet. The inputs for these
calculations are outlined in Table 11. When the Level A isopleth of one
DTH sound source encompasses the isopleth of another DTH sound source,
the sources are considered additive and combined using the rules in
Table 7 as described above. The number of piles per day is altered to
reflect only a single pile for all those that overlap in space and time
(i.e., no double counting of overlapping piles). The maximum strike
rate and duration of the two DTH systems is used in the User
Spreadsheet calculations.
Table 11--NMFS User Spreadsheet Inputs for Simultaneous Use of Two DTH
Hammers
------------------------------------------------------------------------
Spreadsheet tab used (E.2) DTH pile driving
------------------------------------------------------------------------
Weighting Factor Adjustment (kHz)...... 2.
SSL(dB SEL at 10m) \a\
8-in pile/8-in pile................ 147.
8-in pile, 24-in pile.............. 159.
8-in pile, 30-in pile.............. 164.
24-in pile, 24-in pile............. 162.
24-in pile, 30-in pile............. 165.
30-in pile, 30-in pile............. 167.
Activity duration (minutes) within 24 60, 120, 180 or 240 \c\.
hours \b\.
Number of piles per day \b\............ 1.
Strike rate (strikes per second)....... 15 or 25.83 \d\.
------------------------------------------------------------------------
\a\ SSL reflects the combined SSLs calculated in Table 7.
\b\ ADOT anticipates that DTH could occur at one site for up to 10 hours
(600 minutes) per day, and overlap between two sites could occur for
up to 4 hours (240 minutes) per day. Since the potential overlap in
sources is accounted for in the SSL adjustment, and the total
potential duration (even with two hammers) is accounted for in the
``Activity duration (minutes) within 24 hours,'' the ``Number of piles
per day'' is assumed to be 1.
\c\ Duration will vary.
\d\ 25.83 for combinations that include 8-in piles. 15 for all other
combinations.
Level A harassment thresholds for impulsive sound sources (impact
pile driving and DTH) are defined for both SELcum and Peak SPL with the
threshold that results in the largest modeled isopleth for each marine
mammal hearing group used to establish the Level A harassment isopleth.
In this project, Level A harassment isopleths based on cumulative sound
exposure level (SELcum) were always larger than those based on Peak SPL
(for both single hammer use and simultaneous use of two hammers). It
should be noted that there is a duration component when calculating the
Level A harassment isopleth based on SELcum, and this duration depends
on the number of piles that will be driven in a day and strikes per
pile. For some activities, ADOT plans to drive variable numbers of
piles per day throughout the project (See ``Average Piles per Day
(Range)'' in Table 1 in the notice of proposed IHA (87 FR 5980;
February 2, 2022)), and determine at the beginning of each pile driving
day, the maximum number or duration piles will be driven that day.
Here, this flexibility has been accounted for by modeling multiple
durations for the activity, and determining the relevant isopleths.
[[Page 15396]]
Table 12--Distances to Level A Harassment Isopleths, by Hearing Group, and Area of Level A Harassment Zones, for Single Hammer Use During Pile Installation and Removal
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Level A harassment isopleth (m) Level A
Minutes per pile or strikes per ----------------------------------------------------------------- harassment areas
Activity Pile diameter(s) pile (km \2\) all
LF MF HF PW OW hearing groups \a\
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Vibratory Installation.................. 30-inch......................... 60 minutes..................... 8 1 12 5 1 <0.1
24-inch \b\..................... 60 minutes..................... 7 1 11 5 1 <0.1
20-inch......................... 60 minutes..................... 7 1 11 5 1 <0.1
Vibratory Removal....................... 24-inch......................... 60 minutes..................... 7 1 11 5 1 <0.1
DTH Rock Sockets........................ 30-inch......................... 60 minutes..................... 773 28 920 414 31 <0.9
300 minutes.................... 2,258 81 2,690 1,209 88 <3.5
600 minutes.................... 3,584 128 4,269 1,918 140 <6.6
24-inch......................... 60 minutes..................... 359 13 427 192 15 <0.2
300 minutes.................... 1,048 38 1,249 561 41 <1.4
600 minutes.................... 1,664 60 1,982 891 65 <2.4
DTH Tension Anchor...................... 8-inch.......................... 120 minutes.................... 82 3 98 44 4 <0.1
240 minutes.................... 130 5 155 70 6 <0.1
Impact Installation..................... 30-inch......................... 50 strikes..................... 100 4 119 54 4 <0.1
24-inch......................... 50 strikes..................... 54 2 65 29 3 <0.1
20-inch......................... 50 strikes..................... 54 2 65 29 3 <0.1
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Please refer to Table 6-4 of ADOT's IHA application for hearing group-specific areas.
\b\ Includes vibratory installation and removal.
Table 13--Distances to Level A Harassment Isopleths, by Hearing Group for Simultaneous Use of Two DTH Hammers
--------------------------------------------------------------------------------------------------------------------------------------------------------
Level A harassment isopleth (m)
Activity combination Duration -------------------------------------------------------------------------------
LF MF HF PW OW
--------------------------------------------------------------------------------------------------------------------------------------------------------
8-in pile, 8-in pile.................................... 60 82 3 98 44 3
120 130 5 155 70 5
180 170 6 202 91 7
240 206 7 245 110 8
8-in pile, 24-in pile................................... 60 515 18 613 276 20
120 817 29 974 437 32
180 1,071 38 1,276 573 42
240 1,297 46 1,545 694 51
8-in pile, 30-in pile................................... 60 1,109 40 1,321 594 43
120 1,761 63 2,097 942 69
180 2,307 82 2,748 1,235 90
240 2,796 99 3,329 1,496 109
24-in pile, 24-in pile.................................. 60 568 20 677 304 22
120 902 32 1,074 483 35
180 1,181 42 1,407 632 46
240 1,431 51 1,705 766 56
24-in pile, 30-in....................................... 60 900 32 1,072 482 35
120 1,429 51 1,702 765 56
180 1,873 67 2,230 1,002 73
240 2,268 81 2,702 1,214 88
30-in pile, 30-in pile.................................. 60 1,224 44 1,458 655 48
120 1,943 69 2,314 1,040 76
180 2,545 91 3,032 1,362 99
240 3,084 110 3,673 1,650 120
--------------------------------------------------------------------------------------------------------------------------------------------------------
Regarding implications for impact hammers used in combination with
a vibratory hammer or DTH drill, the likelihood of these multiple
sources' isopleths to completely overlap in time is slim primarily
because impact pile driving is intermittent. Furthermore, non-
impulsive, continuous sources rely upon non-impulsive TTS/PTS
thresholds, while impact pile driving uses impulsive thresholds, making
it difficult to calculate isopleths that may overlap from impact
driving and the simultaneous action of a non-impulsive continuous
source or one with multiple strikes per second. Thus, with such slim
potential for multiple different sources' isopleths to overlap in space
and time, specifications should be entered as ``normal'' into the User
Spreadsheet for each individual source separately.
Marine Mammal Occurrence and Take Calculation and Estimation
In this section we provide the information about the presence,
density, or group dynamics of marine mammals that will inform the take
calculations. Additionally, we describe how the occurrence information
is brought together to produce a quantitative take estimate for each
phase. A summary of the estimated take, including as a percentage of
population for each of the species, is shown in Table 14.
Steller Sea Lion
Steller sea lion abundance in the Tongass Narrows area is not well
known. No systematic studies of Steller sea lions have been conducted
in or near the Tongass Narrows area. Steller sea lions are known to
occur year-round and local residents report observing Steller sea lions
approximately once or twice per week (based on communication outlined
in Section 6 of ADOT's IHA application). Abundance
[[Page 15397]]
appears to increase during herring runs (March to May) and salmon runs
(July to September). Group sizes may reach up to 6 to 10 individuals
(Freitag 2017 as cited in 83 FR 37473; August 1, 2018), though groups
of up to 80 individuals have been observed (HDR, Inc. 2003).
ADOT conservatively estimates that one group of 10 Steller sea
lions may be present in the project area each day, but this occurrence
rate may as much as double (20 Steller sea lions per day) during
periods of increased abundance associated with the herring and salmon
runs (March to May and July to September). Therefore, ADOT anticipates
that two large groups (20 individuals) may be taken by Level B
harassment each day during these months. To be conservative, we assume
all 91 days of work could be completed during these months of increased
abundance and thus estimate 1,820 potential takes by Level B harassment
of Steller sea lions in Tongass Narrows (i.e., 2 groups of 10 sea lions
per day x 91 construction days = 1,820 takes by Level B harassment;
Table 14).
ADOT estimates that simultaneous use of two hammers (any
combination) could occur on up to 44 days during the project. On those
days, Level B harassment zones will extend into Clarence Strait.
Steller sea lions are known to swim across Clarence Strait and to use
offshore areas with deeper waters, although no estimates of at-sea
density or abundance in Clarence Strait are available. Therefore, ADOT
has conservatively estimated, and NMFS concurs, that during the 44 days
with potential simultaneous use of two hammers, a group of 10 Steller
sea lions may occur in the portion of the Level B harassment zone in
Clarence Strait each day (one group of 10 sea lions per day x 44 days =
440 individuals). Therefore, the preliminary sum of estimated takes by
Level B harassment of Steller sea lions between Tongass Narrows and
Clarence Strait is 2,260 (1,820 + 440 = 2,260 takes by Level B
harassment).
The largest Level A harassment zone for otariid pinnipeds could
extend 140 m from the noise source for 10 hours of DTH using a single
hammer, or 120m from the noise source for 4 hours of DTH using two
hammers for 30-in piles simultaneously. (As noted previously, ADOT
estimates that simultaneous use of any two hammer types will occur on
no more than 44 days). Zones for shorter durations and other activities
will be smaller (Table 12). For some DTH activities, the estimated
Level A harassment zone is larger than the shutdown zone, and
therefore, some Level A harassment could occur. Further, while
unlikely, it is possible that a Steller sea lion could enter a shutdown
zone without detection given the various obstructions along the
shoreline, and remain in the zone long enough to be taken by Level A
harassment before being observed and a shutdown occurring. ADOT
therefore requested, and NMFS authorized, one take by Level A
harassment on each of the 91 construction days (91 takes by Level A
harassment). Authorized take by Level B harassment was calculated as
the total calculated Steller sea lion takes by Level B harassment minus
the takes by Level A harassment (2,260 takes-91 takes by Level A
harassment) for a total of 2,169 takes by Level B harassment.
Therefore, ADOT requested, and NMFS authorized, 91 takes of Steller sea
lion by Level A harassment and 2,169 takes of Steller sea lion by Level
B harassment (2,260 total takes of Steller sea lion; Table 14).
Harbor Seal
Harbor seal densities in the Tongass Narrows area are not well
known. No systematic studies of harbor seals have been conducted in or
near Tongass Narrows. They are known to occur year-round with little
seasonal variation in abundance (Freitag 2017 as cited in 83 FR 37473;
August 1, 2018) and local experts estimate that there are about 1 to 3
harbor seals in Tongass Narrows every day, in addition to those that
congregate near the seafood processing plants and fish hatcheries. NMFS
has indicated that the maximum group size in Tongass Narrows is three
individuals (83 FR 22009; May 11, 2018); however, ADOT monitoring in
March 2021 observed several groups of up to 5 individuals. Based on
this knowledge, the expected maximum group size in Tongass Narrows is
five individuals. Harbor seals are known to be curious and may approach
novel activity. For these reasons ADOT conservatively estimates that up
to two groups of 5 harbor seals per group could be taken by Level B
harassment due to project-related underwater noise each construction
day for a total of 910 takes by Level B harassment of harbor seal in
Tongass Narrows (i.e., 2 groups of 5 harbor seals per day x 91
construction days = 910 total takes by Level B harassment of harbor
seal; Table 14).
As noted above, ADOT estimates that simultaneous use of two hammers
(any combination) could occur on up to 44 days during the project. On
those days, Level B harassment zones will extend into Clarence Strait.
Harbor seals are known to swim across Clarence Strait, although no
estimates of at-sea density or abundance in Clarence Strait are
available. It is likely that harbor seal abundance in Clarence Strait
is lower than in Tongass Narrows, as harbor seals generally prefer
nearshore waters. Therefore, ADOT has conservatively estimated, and
NMFS concurs, that during the 44 days with potential simultaneous use
of two hammers, a group of 5 harbor seals may occur in the portion of
the Level B harassment zone in Clarence Strait each day (one group of 5
harbor seals per day x 44 days = 220 individuals). Therefore, the sum
of total estimated takes by Level B harassment of harbor seals between
Tongass Narrows and Clarence Strait is 1,130 (910 + 220 = 1,130 takes
by Level B harassment).
The largest Level A harassment zone for harbor seals could extend
1,918 m from the noise source for 10 hours of DTH using a single
hammer, or 1,640 m from the noise source for 4 hours of DTH using two
hammers for 30-in piles simultaneously. (As noted previously, ADOT
estimates that simultaneous use of any two hammer types will occur on
no more than 44 days). Zones for shorter durations and other activities
will be smaller (Table 12). Due to practicability concerns, NMFS is
requiring a 200 m shutdown zone for harbor seals during 24-in and 30-in
DTH activities (Table 15). Therefore, for some DTH activities, the
estimated Level A harassment zone is larger than the shutdown zone, and
therefore, some Level A harassment could occur. Harbor seals may enter
and remain within the area between the Level A harassment zone and the
shutdown zone for a duration long enough to be taken by Level A
harassment. Additionally, while unlikely, it is possible that a harbor
seal could enter a shutdown zone without detection given the various
obstructions along the shoreline, and remain in the zone for a duration
long enough to be taken by Level A harassment before being observed and
a shutdown occurring.
To calculate take by Level A harassment, ADOT first calculated the
ratio of the maximum Level A harassment isopleth for 30-in DTH using a
single hammer minus the shutdown zone isopleth (1,918 m-200 m shutdown
zone = 1,718 m) to the Level B harassment zone isopleth (13,594 m;
1,718 m/13,594 m = 0.1264). ADOT multiplied the resulting ratio by the
total potential take in Tongass Narrows, resulting in 116 takes by
Level A harassment (i.e., 910 takes by Level B harassment x 0.1264 =
116 takes by Level A harassment). NMFS reviewed, and concurs with and
adopts this method. (Potential operation of two DTH hammers for 24-in/
30-in or 30-in/
[[Page 15398]]
30-in pile combinations would result in larger Level A harassment
isopleths than 1,918 m, however, such concurrent work will rarely
occur, if at all, and therefore, NMFS expects that calculating Level A
harassment take using those zones would be overly conservative and
unrealistic. Moreover, since the method used above assumes 30-inch DTH
on all days it provided a precautionary cushion since activities with
smaller Level A harassment zone sizes will occur on many days.)
Authorized take by Level B harassment was calculated as the total
calculated harbor seal takes by Level B harassment minus the takes by
Level A harassment (1,130 takes-116 takes by Level A harassment) for a
total of 1,014 takes by Level B harassment. ADOT therefore requested,
and NMFS authorized, 116 takes of harbor seal by Level A harassment and
1,014 takes of harbor seal by Level B harassment (1,130 total takes of
harbor seal; Table 14).
Harbor Porpoise
Harbor porpoises are non-migratory; therefore, our occurrence
estimates are not dependent on season. Freitag (2017 as cited in 83 FR
37473; August 1, 2018) observed harbor porpoises in Tongass Narrows
zero to one time per month. Harbor porpoises observed in the project
vicinity typically occur in groups of one to five animals with an
estimated maximum group size of eight animals (83 FR 37473, August 1,
2018, Solstice 2018). ADOT's 2020 and 2021 monitoring program in
Tongass Narrows did not result in sightings of this species; however,
ADOT assumes an occurrence rate of one group per month in the following
take estimations. For our analysis, we are considering a group to
consist of five animals. Based on Freitag (2017), and supported by the
reports of knowledgeable locals as described in ADOT's application,
ADOT estimates that one group of five harbor porpoises could enter
Tongass Narrows and potentially taken by Level B harassment due to
project-related noise each month for a total of 15 potential harbor
porpoise takes by Level B harassment in Tongass Narrows (i.e., 1 group
of 5 individuals x 3 months (91 days) = 15 harbor porpoises).
As noted above, ADOT estimates that simultaneous use of two hammers
(any combination) could occur on up to 44 days during the project. On
those days, the Level B harassment zone will extend into Clarence
Strait. Harbor porpoises are known to swim across Clarence Strait and
to use other areas of deep, open waters. Dahlheim et al. (2015)
estimated a density of 0.02 harbor porpoises/km\2\ in an area that
encompasses Clarence Strait. ADOT estimates, and NMFS concurs that
during the 44 days with potential simultaneous use of two hammers, 17
harbor porpoises (0.02 harbor porpoises/km\2\ x 18.5 km\2\ x 44 days =
17 harbor porpoises) may occur in the portion of the Level B harassment
zone in Clarence Strait during the project (though ADOT and NMFS
anticipate that this is a conservative estimate, given the entire 18.5
km\2\ area will rarely be ensonified above the Level B harassment
threshold). Therefore, the sum of total estimated takes by Level B
harassment of harbor porpoise between Tongass Narrows and Clarence
Strait is 32 (15 + 17 = 32 takes by Level B harassment).
The largest Level A harassment zone for harbor porpoises extends
4,269 m from the noise source for 10 hours of DTH using a single
hammer, and 3,673 m from the noise source for 4 hours of DTH using two
hammers for 30-in piles simultaneously. (As noted previously, ADOT
estimates that simultaneous use of any two hammer types will occur on
no more than 44 days). Zones for shorter durations and other activities
will be smaller (Table 12). Due to practicability concerns, NMFS is
requiring a 500 m shutdown zone for high frequency cetaceans during 24-
in and 30-in DTH activities. Therefore, for some DTH activities, the
estimated Level A harassment zone is larger than the shutdown zone, and
therefore, some Level A harassment could occur. Harbor porpoises may
enter and remain within the area between the Level A harassment zone
and the shutdown zone for a duration long enough to be taken by Level A
harassment. Additionally, given the large size of required shutdown
zones for some activities and the cryptic nature of harbor porpoises,
it is possible that a harbor porpoise could enter a shutdown zone
without detection and remain in the zone for a duration long enough to
be taken by Level A harassment before being observed and a shutdown
occurring.
To calculate take by Level A harassment, ADOT first calculated the
ratio of the maximum Level A harassment isopleth for 30-in DTH using a
single hammer minus the shutdown zone isopleth (4,269 m-500 m = 3,769
m) to the Level B harassment zone isopleth (13,594 m; 3,769/13,594 =
0.2773). ADOT multiplied the resulting ratio by the total potential
take in Tongass Narrows, resulting in 5 takes by Level A harassment
(i.e., 15 takes by Level B harassment x 0.2773 = 5 takes by Level A
harassment). NMFS reviewed and concurs with this method. (Potential
operation of two DTH hammers for 24-in/30-in or 30-in/30-in pile
combinations would result in larger Level A harassment isopleths than
4,269 m, however, such concurrent work would rarely occur, if at all,
and therefore, as described above, NMFS expects that calculating Level
A harassment take using those zones is unnecessary.) Authorized take by
Level B harassment was calculated as the total calculated harbor
porpoise takes by Level B harassment minus the takes by Level A
harassment (32 takes-5 takes by Level A harassment) for a total of 27
takes by Level B harassment. ADOT therefore requested and NMFS
authorized 5 takes by Level A harassment and 27 takes by Level B
harassment (32 total takes of harbor porpoise; Table 14).
Dall's Porpoise
Dall's porpoises are expected to only occur in the project area a
few times per year. Their relative rarity is supported by Jefferson et
al.'s (2019) presentation of historical survey data showing very few
sightings in the Ketchikan area and conclusion that Dall's porpoise
generally are rare in narrow waterways, like the Tongass Narrows.
ADOT's monitoring program from 2020 and 2021 recorded one sighting of 6
individuals over 23 days of observation, 16 days of observations with
no sightings, and two sightings of 10 individuals in 14 days of
observation; this equates to one sighting every approximately 17 days
(DOT&PF 2020, 2021a, 2021b, 2021c, 2021d) or approximately two
sightings per month. This species is non-migratory; therefore, the
occurrence estimates are not dependent on season. ADOT anticipates that
one large Dall's porpoise pod (12 individuals) may be present in the
project area and exposed to project related underwater noise twice each
month during 3 months of construction (91 days rounded to 3 months) for
a total of 72 potential takes by Level B harassment in Tongass Narrows
(i.e., 2 groups of 12 Dall's porpoises per month x 3 months = 72
potential takes by Level B harassment).
As noted above, ADOT estimates that simultaneous use of two hammers
(any combination) could occur on up to 44 days during the project. On
those days, the Level B harassment zone will extend into Clarence
Strait, where Dall's porpoises are known to occur. Jefferson et al.
(2019) estimated an average density of 0.19 Dall's porpoises/km\2\ in
Southeast Alaska. ADOT estimates, and NMFS concurs, that during the 44
days with potential simultaneous use of two hammers, 155 Dall's
porpoises (0.19 Dall's porpoises/km\2\ x 18.5 km\2\ x 44 days = 155
Dall's porpoises) may occur
[[Page 15399]]
in the portion of the Level B harassment zone in Clarence Strait during
the project (though ADOT and NMFS anticipate that this is a
conservative estimate, given the entire 18.5 km\2\ area will rarely be
ensonified above the Level B harassment threshold). Therefore, the sum
of total estimated takes by Level B harassment of harbor porpoise
between Tongass Narrows and Clarence Strait is 227 (72 + 155= 227 takes
by Level B harassment).
The largest Level A harassment zone for Dall's porpoises extends
4,269 m from the noise source for 10 hours of DTH using a single
hammer, and 3,673 m from the noise source for 4 hours of DTH using two
hammers for 30-in piles simultaneously. (As noted previously, ADOT
estimates that simultaneous use of any two hammer types will occur on
no more than 44 days.) Zones for shorter durations and other activities
will be smaller (Table 12). Due to practicability concerns, NMFS
proposes to require a 500 m shutdown zone for high frequency cetaceans
during 24-in and 30-in DTH activities. Therefore, for some DTH
activities, the estimated Level A harassment zone is larger than the
shutdown zone, and therefore, some Level A harassment could occur.
Dall's porpoises may enter and remain within the area between the Level
A harassment zone and the shutdown zone and be exposed to sound levels
for a duration long enough to be taken by Level A harassment.
Additionally, given the large size of the required shutdown zones for
some activities, it is possible that a Dall's porpoise could enter a
shutdown zone without detection and remain in the zone for a duration
long enough to taken by Level A harassment before being observed and a
shutdown occurring.
To calculate take by Level A harassment, ADOT first calculated the
ratio of the maximum Level A harassment isopleth for 30-in DTH using a
single hammer minus the shutdown zone isopleth (4,269 m-500 m = 3,769
m) to the Level B harassment zone isopleth (13,594 m; 3,769/13,594 =
0.2773). ADOT multiplied the resulting ratio by the total potential
take in Tongass Narrows, resulting in 20 takes by Level A harassment
(i.e., 72 takes by Level B harassment x 0.2773 = 20 takes by Level A
harassment). NMFS revised and concurs with this method. (Potential
operation of two DTH hammers for 24-in/30-in or 30-in/30-in pile
combinations would result in larger Level A harassment isopleths than
4,269 m, however, such concurrent work would rarely occur, if at all,
and therefore, as described above, NMFS expects that calculating Level
A harassment take using those zones is unnecessary.) Authorized take by
Level B harassment was calculated as the total calculated Dall's
porpoise takes by Level B harassment minus the takes by Level A
harassment (227 takes-20 takes by Level A harassment) for a total of
207 takes by Level B harassment. ADOT therefore requested and NMFS
authorized 20 takes by Level A harassment, and 207 takes by Level B
harassment (227 total takes of Dall's porpoise; Table 14).
Pacific White-Sided Dolphin
Pacific white-sided dolphins do not generally occur in the shallow,
inland waterways of Southeast Alaska. There are no records of this
species occurring in Tongass Narrows, and it is uncommon for
individuals to occur in the project area. However, historical sightings
in nearby areas (Dahlheim and Towell 1994; Muto et al. 2018) and recent
fluctuations in distribution and abundance mean it is possible the
species could be present.
To account for the possibility that this species could be present
in the project area, ADOT conservatively estimates, and NMFS concurs,
that one large group (92 individuals) of Pacific white-sided dolphins
may be taken by Level B harassment in Tongass Narrows during the
activity.
As noted above, ADOT estimates that simultaneous use of two hammers
(any combination) could occur on up to 44 days during the project. On
those days, the Level B harassment zone will extend into Clarence
Strait. However, no additional takes of Pacific white-sided dolphin are
anticipated to occur due to simultaneous use of two hammers, given that
Pacific white-sided dolphins are uncommon in the project area.
Therefore, NMFS authorized 92 takes by Level B harassment of Pacific
white-sided dolphins.
ADOT did not request, nor did NMFS authorize take by Level A
harassment for this activity given that Pacific white-sided dolphins
are uncommon in the project area. Further, considering the small Level
A harassment zones for mid-frequency cetaceans (Table 12 and Table 13)
in comparison to the required shutdown zones, it is unlikely that a
Pacific white-sided dolphin will enter and remain within the area
between the Level A harassment zone and the shutdown zone for a
duration long enough to be taken by Level A harassment.
Killer Whale
Killer whales are observed in Tongass Narrows irregularly with
peaks in abundance between May and July. During 7 months of
intermittent marine mammal monitoring (October 2020-February 2021; May-
June 2021), there were five killer whale sightings in 4 months
(November, February, May, June) totaling 22 animals; sightings occurred
on 5 out of 88 days of monitoring (DOT&PF 2020, 2021a, 2021b, 2021c,
2021d). Pod sizes ranged from two to eight animals (DOT&PF 2020, 2021a,
2021b, 2021c, 2021d). Previous incidental take authorizations in the
Ketchikan area have estimated killer whale occurrence in Tongass
Narrows at one pod per month, except during the peak period of May to
July when estimates have included two pods per month (Freitag 2017 as
cited in 83 FR 37473; August 1, 2018 and 83 FR 34134; July 17, 2019).
As noted above, ADOT estimates that simultaneous use of two hammers
(any combination) could occur on up to 44 days during the project. On
those days, the Level B harassment zone will extend into Clarence
Strait. In estimating take by Level B harassment, ADOT assumed a pod
size of 12 killer whales, that all 91 days of work will occur between
May and July during the peaks in abundance, and that therefore, 2 pods
may occur within the Level B harassment zone (including both Tongass
Narrows and Clarence Strait) during each month of work, for a total of
72 takes by Level B harassment (2 groups x 12 individuals x 3 months =
72 killer whales). Therefore, ADOT estimates that a total of 72 killer
whales may be taken by Level B harassment (i.e., 2 pods of 12
individuals per month x 3 months (91 days) = 72 takes by Level B
harassment). NMFS reviewed and concurs with this method, and authorized
72 takes by Level B harassment of killer whale.
ADOT did not request, nor did NMFS authorize take by Level A
harassment of killer whales for this activity. Considering the small
Level A harassment zones for mid-frequency cetaceans (Table 12 and
Table 13) in comparison to the required shutdown zones, it is unlikely
that a killer whale will enter and remain within the area between the
Level A harassment zone and the shutdown zone for a duration long
enough to be taken by Level A harassment.
Humpback Whale
As discussed in the Description of Marine Mammals in the Area of
Specified Activities section, locals have observed humpback whales an
average of about once per week in Tongass Narrows, but there is
evidence to suggest occurrence may be higher during some periods of the
year. The December 19, 2019 Biological Opinion
[[Page 15400]]
stated that based on observations by local experts, approximately one
group of two individuals will occur in Tongass Narrows during ADOT's
activity two times per seven days during pile driving, pile removal,
and DTH activities throughout the year. The assumption was based on
differences in abundance throughout the year, recent observations of
larger groups of whales present during summer, and a higher than
average frequency of occurrence in recent months (NMFS 2019). ADOT's
2020 and 2021 monitoring program documented a similar sighting rate,
with 30 humpback whale sightings over 53 days of in-water pile driving;
some of the sightings were believed to be repeated sightings of the
same individual (DOT&PF 2020, 2021a, 2021b, 2021c, 2021d). ADOT
therefore predicts, and NMFS concurs, that one group of two individuals
may occur within the Level B harassment zones twice per week during the
planned activities. As noted previously, ADOT estimates that pile
driving will occur over the course of 91 days (13 weeks). Therefore,
ADOT estimates, and NMFS concurs that 52 takes by Level B harassment of
humpback whales (1 group of 2 individuals x 2 groups per week x 13
weeks = 52 takes by Level B harassment) from the Central North Pacific
stock may occur in Tongass Narrows.
As noted above, ADOT estimates that simultaneous use of two hammers
(any combination) could occur on up to 44 days during the project. On
those days, the Level B harassment zone will extend into Clarence
Strait. Local specialists estimated that approximately four humpback
whales could pass through or near the portion of the Level B harassment
zone in Clarence Strait each day. Therefore, ADOT estimates, and NMFS
concurs, that during the 44 days with potential simultaneous use of two
hammers, 176 takes by Level B harassment of humpback whale could occur
in Clarence Strait (4 humpback whales x 44 days = 176 takes by Level B
harassment). Therefore, the sum of total estimated takes by Level B
harassment of humpback whale between Tongass Narrows and Clarence
Strait is 228 (52 + 176 = 228 takes by Level B harassment), and NMFS
authorized 228 takes by Level B harassment of humpback whale.
As noted previously, Wade et al. (2021) estimates that
approximately 2 percent of all humpback whales in Southeast Alaska and
northern British Columbia are of the Mexico DPS, while all others are
of the Hawaii DPS. However, NMFS has conservatively assumed here that
6.1 percent of the total humpback population in Southeast Alaska is
from the Mexico DPS (Wade et al. 2016). Therefore, of the 228 takes of
humpback whale authorized, NMFS expects that a total of 14 takes will
be of individuals from the Mexico DPS. NMFS expects that all other
instances of take will be from the non-listed Hawaii DPS.
Take by Level A harassment of humpback whales is neither
anticipated nor authorized because of the expected effectiveness of the
required monitoring and mitigation measures (see Mitigation Measures
section below for more details). For all pile driving and DTH
activities, the shutdown zone exceeds the calculated Level A harassment
zone. Humpbacks are usually readily visible, and therefore, we expect
protected species observers (PSOs) to be able to effectively implement
the required shutdown measures prior to any humpback whales incurring
PTS within Level A harassment zones.
Minke Whales
Minke whales may be present in Tongass Narrows year-round. Their
abundance throughout Southeast Alaska is very low, and anecdotal
reports have not included minke whales near the project area. ADOT's
monitoring program in Tongass Narrows also did not report any minke
whale sightings. However, minke whales are distributed throughout a
wide variety of habitats and could occur near the project area. Minke
whales are generally sighted as solo individuals (Dahlheim et al.
2009).
As noted above, ADOT estimates that simultaneous use of two hammers
(any combination) could occur on up to 44 days during the project. On
those days, the Level B harassment zone will extend into Clarence
Strait. Based on Freitag (2017; as cited in 83 FR 37473; August 1, 2018
and 83 FR 34134; July 17, 2019), ADOT estimates that three individual
minke whales may occur near or within the Level B harassment zone
(including both Tongass Narrows and Clarence Strait) every four months.
Based on that estimated occurrence rate, NMFS estimates that 3 minke
whales may occur in the Level B harassment zone during the planned
activities (occurring over approximately 3 months), and authorized 3
takes by Level B harassment of minke whales (Table 14).
The largest Level A harassment zone for minke whale extends 3,584 m
from the noise source for 10 hours of DTH using a single hammer, and
3,084 m from the noise source for 4 hours of DTH using two hammers for
30-in piles simultaneously. (As noted previously, ADOT estimates that
simultaneous use of any two hammer types will occur on no more than 44
days.) Zones for shorter durations and other activities will be smaller
(Table 13). NMFS required a 1,500 m shutdown zone for minke whales
during 24-in and 30-in DTH activities. Therefore, for some DTH
activities, the estimated Level A harassment zone is larger than the
required shutdown zone, and Level A harassment could occur.
To calculate take by Level A harassment, ADOT first calculated the
ratio of the maximum Level A harassment isopleth for 30-in DTH using a
single hammer minus the shutdown zone isopleth (3,584 m-1,500 m = 2,084
m) to the Level B harassment zone isopleth (13,594 m; 2,084 m/13,594 m
= 0.1533). ADOT multiplied the resulting ratio by the total potential
take by Level B harassment, resulting in 1 take by Level A harassment
(i.e., 3 takes by Level B harassment x 0.1533 = 1 take by Level A
harassment). NMFS reviewed and concurs with this method. (Potential
operation of two DTH hammers for 24-in/30-in or 30-in/30-in pile
combinations would result in larger Level A harassment isopleths than
4,269 m, however, such concurrent work would rarely occur, if at all,
and therefore, as described above NMFS expects that calculating Level A
harassment take using those zones is unnecessary.) Take by Level B
harassment was calculated as the total potential minke whale takes by
Level B harassment minus the takes by Level A harassment. ADOT
therefore requested, and NMFS authorized 1 take by Level A harassment
and 2 takes by Level B harassment (3 total takes of minke whale; Table
14).
[[Page 15401]]
Table 14--Authorized Take as a Percentage of Stock Abundance, by Stock and Harassment Type
----------------------------------------------------------------------------------------------------------------
Authorized take
------------------------------------------------ Percent of
Species DPS/stock Level A Level B stock
harassment harassment Total
----------------------------------------------------------------------------------------------------------------
Steller sea lion.............. Eastern U.S..... 91 2,169 2,260 5.2
Harbor seal................... Clarence Strait. 116 1,014 1,130 4.1
Harbor porpoise............... Southeast Alaska 5 27 32 2.5
Dall's porpoise............... Alaska.......... 20 207 227 1.7
Pacific white-sided dolphin... North Pacific... 0 92 92 0.3
---------------------------------------------------------------------------------
Killer whale.................. Alaska Resident. 0 72 72 \a\ 3.1
West Coast \a\ 20.1
Transient
Northern \a\ 23.8
Resident
Humpback whale................ Central North 0 228 228 2.3
Pacific.
Minke whale................... Alaska.......... 1 2 3 N/A
----------------------------------------------------------------------------------------------------------------
\a\ Conservatively assumes that all 72 takes occur to each stock.
Mitigation Measures
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. 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.
Because of the need for an ESA Section 7 consultation for effects
of the project on ESA listed humpback whales, there are a number of
mitigation measures that go beyond, or are in addition to, typical
mitigation measures we would otherwise require for this sort of
project. However, these measures are typical for actions in the
Ketchikan area. The mitigation measures included herein include
measures that align with the 2019 Biological Opinion. ADOT must employ
the following mitigation measures as included in the proposed IHA:
Avoid direct physical interaction with marine mammals
during construction activity. If a marine mammal comes within 10 m of
such activity, operations must cease and vessels must reduce speed to
the minimum level required to maintain steerage and safe working
conditions (note that NMFS expects that a 10 m shutdown zone is
sufficient to avoid direct physical interaction with marine mammals,
but ADOT conservatively proposed a 20 m shutdown zone to avoid physical
interaction for in-water other than vessel transit);
Ensure that construction supervisors and crews, the
monitoring team and relevant ADOT staff are trained prior to the start
of all pile driving and DTH activity, so that responsibilities,
communication procedures, monitoring protocols, and operational
procedures are clearly understood. New personnel joining during the
project must be trained prior to commencing work;
Pile driving activity must be halted upon observation of
either a species for which incidental take is not authorized or a
species for which incidental take has been authorized but the
authorized number of takes has been met, entering or within the
harassment zone;
For any marine mammal species for which take by Level B
harassment has not been requested or authorized, in-water pile
installation/removal and DTH will shut down immediately when the
animals are sighted;
Employ PSOs and establish monitoring locations as
described in the Marine Mammal Monitoring Plan and Section 5 of the
IHA. The Holder must monitor the project area to the maximum extent
possible based on the required number of PSOs, required monitoring
locations, and environmental conditions. For all pile driving and
removal at least three PSOs must be used;
The placement of the PSOs during all pile driving and
removal and DTH activities will ensure that the entire shutdown zone is
visible during pile installation;
Monitoring must take place from 30 minutes prior to
initiation of pile driving or DTH activity (i.e., pre-clearance
monitoring) through 30 minutes post-completion of pile driving or DTH
activity;
If in-water work ceases for more than 30 minutes, ADOT
will conduct pre-clearance monitoring of both the Level B harassment
zone and shutdown zone;
Pre-start clearance monitoring must be conducted during
periods of visibility sufficient for the lead PSO to determine that the
shutdown zones indicated in Table 15 are clear of marine mammals. Pile
driving may commence following 30 minutes of observation when the
determination is made that the shutdown zones are clear of marine
mammals;
If a marine mammal is observed entering or within the
shutdown zones
[[Page 15402]]
indicated in Table 15, pile driving must be delayed or halted. If pile
driving is delayed or halted due to the presence of a marine mammal,
the activity may not commence or resume until either the animal has
voluntarily exited and been visually confirmed beyond the shutdown zone
(Table 15) or 15 minutes have passed without re-detection of the animal
(30 minutes for humpback whales);
As required by the 2019 Biological Opinion, if waters
exceed a sea state that restricts the PSOs' ability to make
observations within the shutdown zone, in-water pile installation and
removal will cease. Pile installation and removal will not be initiated
or continue until the appropriate shutdown zone is visible in its
entirety;
For humpback whales, if the boundaries of the harassment
zone have not been monitored continuously during a work stoppage, the
entire harassment zone will be surveyed again to ensure that no
humpback whales have entered the harassment zone that were not
previously accounted for;
In-water activities will take place only: Between civil
dawn and civil dusk when PSOs can effectively monitor for the presence
of marine mammals; during conditions with a Beaufort Sea State of 4 or
less; when the entire shutdown zone and adjacent waters are visible
(e.g., monitoring effectiveness is not reduced due to rain, fog, snow,
etc.). Pile driving may continue for up to 30 minutes after sunset
during evening civil twilight, as necessary to secure a pile for safety
prior to demobilization for the evening. PSO(s) will continue to
observe shutdown and monitoring zones during this time. The length of
the post-activity monitoring period may be reduced if darkness
precludes visibility of the shutdown and monitoring zones;
Vessel operators will implement the following required
measures: Maintain a watch for marine mammals at all times while
underway; remain at least and at least 91 m (100 yards (yd)) from all
other listed marine mammals, travel at less than 5 knots (9 km/hr) when
within 274 m (300 yd) of a whale; avoid changes in direction and speed
when within 274 m (300 yd) of whales, unless doing so is necessary for
maritime safety; not position vessel(s) in the path of whales, and will
not cut in front of whales in a way or at a distance that causes the
whales to change their direction of travel or behavior (including
breathing/surfacing pattern); check the waters immediately adjacent to
the vessel(s) to ensure that no whales will be injured when the
propellers are engaged; adhere to the Alaska Humpback Whale Approach
Regulations when transiting to and from the project site (see 50 CFR
216.18, 223.214, and 224.103(b)); not allow lines to remain in the
water, and not throw trash or other debris overboard, thereby reducing
the potential for marine mammal entanglement; follow established
transit routes and travel <10 knots while in the harassment zones;
follow the speed limit within Tongass Narrows (7 knots for vessels over
23 ft in length). If a whale's course and speed are such that it will
likely cross in front of a vessel that is underway, or approach within
91 m (100 yards (yd)) of the vessel, and if maritime conditions safely
allow, the engine will be put in neutral and the whale will be allowed
to pass beyond the vessel, except that vessels will remain 460 m (500
yd) from North Pacific right whales; if a humpback whale comes within
10 m (32.8 ft) of a vessel during construction, the vessel will reduce
speed to the minimum level required to maintain safe steerage and
working conditions until the humpback whale is at least 10 m (32.8 ft)
away from the vessel; vessels are prohibited from disrupting the normal
behavior or prior activity of a whale by any other act or omission.
ADOT must use soft start techniques when impact pile
driving. Soft start requires contractors to provide an initial set of
three strikes at reduced energy, followed by a 30-second waiting
period, then two subsequent reduced-energy strike sets. A soft start
must be implemented at the start of each day's impact pile driving and
at any time following cessation of impact pile driving for a period of
30 minutes or longer; and
If take by Level B harassment reaches the authorized limit
for an authorized species, pile installation will be stopped as these
species approach the Level B harassment zone to avoid additional take
of them.
Further, on days when simultaneous use of two hammers producing
continuous noise (two DTH hammers, one DTH and one vibratory hammer, or
two vibratory hammers) is expected:
When combinations of one DTH hammer with a vibratory
hammer or two DTH hammers are used simultaneously, each PSO of the two
contractors will have three PSOs working and the PSO teams will work
together to monitor the entire area;
One or more PSOs will be present at each construction site
during in-water pile installation and removal so that Level A
harassment zones and shutdown zones are monitored by a dedicated PSO at
all times.
The ADOT environmental coordinator for the project will
implement coordination between or among the PSO contractors. ADOT will
include in the contracts that PSOs must coordinate, collaborate, and
otherwise work together to ensure compliance with project permits and
authorizations.
The following specific mitigation measures will also apply to
ADOT's in-water construction activities:
Establishment of Level A Harassment Zones and Shutdown Zones--For
all pile driving/removal and DTH activities, ADOT will establish a
shutdown zone (Table 15). The purpose of a shutdown zone is generally
to define an area within which shutdown of activity will occur upon
sighting of a marine mammal (or in anticipation of an animal entering
the defined area). Shutdown zones vary based on the activity type and
duration and marine mammal hearing group (Table 15). For vibratory
installation and removal and impact installation, shutdown zones will
be based on the Level A harassment isopleth distances for each hearing
group.
ADOT anticipates that the daily duration of DTH use may vary
significantly, with large differences in maximum zones sizes possible
depending on the work planned for a given day. Given this uncertainty
and concerns related to ESA-listed humpback whales, ADOT will utilize a
tiered system to identify and monitor the appropriate Level A
harassment zones and shutdown zones, based on the maximum expected DTH
duration. At the start of any work involving DTH, ADOT will first
determine whether DTH may occur at two sites concurrently or just at
one site. If DTH may occur at two sites concurrently, then ADOT will
implement the Level A harassment zones and shutdown zones associated
with simultaneous DTH use of the relevant pile sizes (Table 13 and
Table 15). If DTH may only occur at one site, ADOT will then determine
the maximum duration of DTH possible that day (according to the defined
duration intervals in Table 15), which will determine the appropriate
Level A harassment isopleth for that day (Table 12 and Table 13). This
Level A harassment zone and associated shutdown zone must be observed
by PSO(s) for the entire work day or until it is determined that, given
the duration of activity for the day, the Level A harassment isopleth
cannot exceed the next lower Level A harassment isopleth size in Table
12.
Due to practicability concerns, shutdown zones for some species
during some activities may be smaller than the Level A harassment
isopleths (Table 15). The placement of PSOs during all pile
[[Page 15403]]
driving, pile removal, and DTH activities (described in detail in the
Monitoring and Reporting section) will ensure that the entire shutdown
zones are visible during pile installation.
Table 15--Shutdown Zones and Level B Harassment Isopleths for Each Activity
--------------------------------------------------------------------------------------------------------------------------------------------------------
Shutdown distances (m)
Minutes per ------------------------------------------------------------------------------ Level B
Activity Pile size pile or strikes LF harassment
(in) per pile (humpback LF (minke MF HF PW OW isopleth
whales) whales) (m)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Vibratory Installation......... 30 60 min......... 50 20 6,310
24 60 min 5,412
20 60 min
--------------------------------------------------------------------------------------------------------------------------------------------------------
Vibratory Removal.............. 24 60 min
--------------------------------------------------------------------------------------------------------------------------------------------------------
DTH of Rock Sockets............ 30 60 min......... 780 1,500 30 500 200 40 13,594
120 min........ 1,300 50 50
180 min........ 1,700 60 70
240 min........ 2,000 70 80
300 min........ 2,300 90 90
360 min........ 2,600 100 100
420 min........ 2,900
480 min........ 3,100
540 min........ 3,400
600 min........ 3,600 130 100
24 60 min......... 360 1,500 20 500 200 20
120 min........ 570 30 30
180 min........ 750 30 30
240 min........ 910 40 40
300 min........ 1,100 40 50
360 min........ 1,200 50 50
420 min........ 1,400 50 60
480 min........ 1,500 60 60
540 min........ 1,600 60 70
600 min........ 1,700 60 70
--------------------------------------------------------------------------------------------------------------------------------------------------------
DTH of Tension Anchor.......... 8 120 min........ 90 90 20 100 50 20
240 min........ 130 130 160 70
--------------------------------------------------------------------------------------------------------------------------------------------------------
Impact Installation............ 30 50 strikes..... 100 100 20 120 60 20 2,154
24 50 strikes..... 60 60 70 30 1,000
20 50 strikes
--------------------------------------------------------------------------------------------------------------------------------------------------------
Table 16--Shutdown Zones, by Hearing Group for Simultaneous Use of Two DTH Hammers
--------------------------------------------------------------------------------------------------------------------------------------------------------
Level A harassment isopleth (m)
Activity combination Duration -------------------------------------------------------------------------------
(minutes) LF MF HF PW OW
--------------------------------------------------------------------------------------------------------------------------------------------------------
8-in pile, 8-in pile.................................... 60 90 20 100 50 20
120 130 160 70
180 170 200 100
240 210 250 110
--------------------------------------------------------------------------------------------------------------------------------------------------------
8-in pile, 24-in pile................................... 60 520 20 500 200 20
120 820 30 40
180 1,080 40 50
240 1,300 50 60
--------------------------------------------------------------------------------------------------------------------------------------------------------
8-in pile, 30-in pile................................... 60 1,110 40 50
120 1,770 70 70
180 2,310 90 90
240 2,800 100 110
--------------------------------------------------------------------------------------------------------------------------------------------------------
24-in pile, 24-in pile.................................. 60 570 20 30
120 910 32 40
180 1,190 42 50
240 1,440 60 60
--------------------------------------------------------------------------------------------------------------------------------------------------------
24-in pile, 30-in....................................... 60 900 40 40
120 1,430 60 60
180 1,880 70 80
240 2,270 90 90
--------------------------------------------------------------------------------------------------------------------------------------------------------
30-in pile, 30-in pile.................................. 60 1,230 50 50
120 1,950 70 80
[[Page 15404]]
180 2,550 100 100
240 3,090 110 120
--------------------------------------------------------------------------------------------------------------------------------------------------------
ADOT also must abide by the terms and conditions of the December
19, 2019 Biological Opinion and Incidental Take Statement issued by
NMFS pursuant to section 7 of the Endangered Species Act.
Based on our evaluation of the applicant's proposed measures, as
well as other measures considered by NMFS, NMFS has determined that the
required 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.
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
project 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).
Mitigation and monitoring effectiveness.
Visual Monitoring
Monitoring must be conducted by qualified, NMFS-approved PSOs, in
accordance with the following:
PSOs must be independent (i.e., not construction
personnel) and have no other assigned tasks during monitoring periods.
At least one PSO must have prior experience performing the duties of a
PSO during construction activity pursuant to a NMFS-issued IHA. Other
PSOs may substitute other relevant experience, education (degree in
biological science or related field), or training for prior experience
performing the duties of a PSO during construction activity pursuant to
a NMFS-issued IHA. Where a team of three or more PSOs is required, a
lead observer or monitoring coordinator must be designated. The lead
observer must have prior experience performing the duties of a PSO
during construction activity pursuant to a NMFS-issued incidental take
authorization. PSOs must be approved by NMFS prior to beginning any
activity subject to this IHA; and
PSOs must record all observations of marine mammals as
described in the Section 5 of the IHA and the Marine Mammal Monitoring
Plan, regardless of distance from the pile being driven. PSOs shall
document any behavioral reactions in concert with distance from piles
being driven or removed;
PSOs must have the following additional qualifications:
Ability to conduct field observations and collect data
according to assigned protocols;
Experience or training in the field identification of
marine mammals, including the identification of behaviors;
Sufficient training, orientation, or experience with the
construction operation to provide for personal safety during
observations;
Writing skills sufficient to prepare a report of
observations including but not limited to the number and species of
marine mammals observed; dates and times when in-water construction
activities were conducted; dates, times, and reason for implementation
of mitigation (or why mitigation was not implemented when required);
and marine mammal behavior; and
Ability to communicate orally, by radio or in person, with
project personnel to provide real-time information on marine mammals
observed in the area as necessary;
Additionally, as required by NMFS' December 2019 Biological
Opinion, each PSO will be trained and provided with reference materials
to ensure standardized and accurate observations and data collection.
ADOT must employ three PSOs during all pile driving and DTH. A
minimum of one PSO (the lead PSO) must be assigned to the active pile
driving or DTH location to monitor the shutdown zones and as much of
the Level B harassment zones as possible. Two additional PSOs are also
required, though the observation points may vary depending on the
construction activity and location of the piles. To select the best
observation locations, prior to start of construction, the lead PSO
will stand at the construction site to monitor the Level A harassment
zones while two or more PSOs travel in opposite directions from the
project site along Tongass Narrows until they have reached the edge of
the appropriate Level B harassment zone, where they will identify
suitable observation points from which to observe. When needed, an
additional PSO will be stationed on the north end of Revilla Island
observing to the northwest. See Figure 2-11 of ADOT's Marine Mammal
[[Page 15405]]
Monitoring and Mitigation Plan for a map of planned PSO locations. If
visibility deteriorates so that the entire width of Tongass Narrows at
the harassment zone boundary is not visible, additional PSOs may be
positioned so that the entire width is visible, or work will be halted
until the entire width is visible to ensure that any humpback whales
entering or within the harassment zone are detected by PSOs.
When DTH use occurs, or simultaneous use of one DTH with a
vibratory hammer or two DTH systems occurs, creating Level B harassment
zones that exceed 13 km and 21 km, respectively, and Level A harassment
zones that extend over 6 km, one additional PSO will be stationed at
the northernmost land-based location at the entrance to Tongass Narrows
(at least two PSOs total at that location, four PSOs on duty across all
PSO locations). One of these PSO will focus on Tongass Narrows,
specifically watching for marine mammals that could approach or enter
Tongass Narrows and the project area. The second PSO will look out into
Clarence Strait, watching for marine mammals that could swim through
the ensonified area. No additional PSOs will be required at the
southern-most monitoring location because the Level B harassment zones
are truncated to the southeast by islands, which prevent propagation of
sound in that direction beyond the confines of Tongass Narrows. Takes
by Level B harassment will be recorded by PSOs and extrapolated based
upon the number of observed takes and the percentage of the Level B
harassment zone that was not visible.
Each construction contractor managing an active construction site
and on-going in-water pile installation or removal will provide
qualified, independent PSOs for their specific contract. The ADOT
environmental coordinator for the project will implement coordination
between or among the PSO contractors. It will be a required component
of their contracts that PSOs coordinate, collaborate, and otherwise
work together to ensure compliance with project permits and
authorizations.
Reporting
A draft marine mammal monitoring report will be submitted to NMFS
within 90 days after the completion of pile driving and removal
activities, or 60 days prior to a requested date of issuance of any
future IHAs for projects at the same location, whichever comes first.
The report will include an overall description of work completed, a
narrative regarding marine mammal sightings, and associated PSO data
sheets. Specifically, the report must include:
Dates and times (begin and end) of all marine mammal
monitoring;
Construction activities occurring during each daily
observation period, including the number and type of piles driven or
removed and by what method (i.e., impact, vibratory or DTH) and the
total equipment duration for vibratory removal or DTH for each pile or
hole or total number of strikes for each pile (impact driving);
PSO locations during marine mammal monitoring;
Environmental conditions during monitoring periods (at
beginning and end of PSO shift and whenever conditions change
significantly), including Beaufort sea state and any other relevant
weather conditions including cloud cover, fog, sun glare, and overall
visibility to the horizon, and estimated observable distance;
Upon observation of a marine mammal, the following
information: Name of PSO who sighted the animal(s) and PSO location and
activity at time of sighting; Time of sighting; Identification of the
animal(s) (e.g., genus/species, lowest possible taxonomic level, or
unidentified), PSO confidence in identification, and the composition of
the group if there is a mix of species; Distance and bearing of each
marine mammal observed relative to the pile being driven for each
sighting (if pile driving was occurring at time of sighting); Estimated
number of animals (min/max/best estimate); Estimated number of animals
by cohort (adults, juveniles, neonates, group composition, sex class,
etc.); Animal's closest point of approach and estimated time spent
within the harassment zone; Description of any marine mammal behavioral
observations (e.g., observed behaviors such as feeding or traveling),
including an assessment of behavioral responses thought to have
resulted from the activity (e.g., no response or changes in behavioral
state such as ceasing feeding, changing direction, flushing, or
breaching);
Number of marine mammals detected within the harassment
zones and shutdown zones, by species;
Table summarizing any incidents resulting in take of ESA-
listed species;
Detailed information about any implementation of any
mitigation triggered (e.g., shutdowns and delays), a description of
specific actions that ensued, and resulting changes in behavior of the
animal(s), if any;
Description of other human activity within each monitoring
period;
Description of any deviation from initial proposal in pile
numbers, pile types, average driving times, etc.;
Brief description of any impediments to obtaining reliable
observations during construction period;
Description of any impediments to complying with these
mitigation measures; and
If visibility degrades to where the PSO(s) cannot view the
entire impact or vibratory harassment zones, take of humpback whales
will be extrapolated based on the estimated percentage of the
monitoring zone that remains visible and the number of marine mammals
observed.
If no comments are received from NMFS within 30 days, the draft
final report will constitute the final report. If comments are
received, a final report addressing NMFS comments must be submitted
within 30 days after receipt of comments.
Reporting Injured or Dead Marine Mammals
In the event that personnel involved in the construction activities
discover an injured or dead marine mammal, the IHA-holder must
immediately cease the specified activities and report the incident to
the Office of Protected Resources (OPR)
([email protected]), NMFS and to the Alaska Regional
Stranding Coordinator as soon as feasible. If the death or injury was
clearly caused by the specified activity, ADOT must immediately cease
the specified activities until NMFS is able to review the circumstances
of the incident and determine what, if any, additional measures are
appropriate to ensure compliance with the terms of the IHA. The IHA-
holder must not resume their activities until notified by NMFS. The
report must include the following information:
Time, date, and location (latitude/longitude) of the first
discovery (and updated location information if known and applicable);
Species identification (if known) or description of the
animal(s) involved;
Condition of the animal(s) (including carcass condition if
the animal is dead);
Observed behaviors of the animal(s), if alive;
If available, photographs or video footage of the
animal(s); and
General circumstances under which the animal was
discovered.
[[Page 15406]]
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' 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 species listed in
Table 1 for which take could occur, given that NMFS expects the
anticipated effects of the planned pile driving/removal and DTH on
different marine mammal stocks to be similar in nature. Where there are
meaningful differences between species or stocks, or groups of species,
in anticipated individual responses to activities, impact of expected
take on the population due to differences in population status, or
impacts on habitat, NMFS has identified species-specific factors to
inform the analysis.
Pile driving and DTH activities associated with the project, as
outlined previously, have the potential to disturb or displace marine
mammals. Specifically, the specified activities may result in take, in
the form of Level B harassment and, for some species Level A
harassment, from underwater sounds generated by pile driving and DTH.
Potential takes could occur if marine mammals are present in zones
ensonified above the thresholds for Level B harassment or Level A
harassment, identified above, while activities are underway.
NMFS does not anticipate that serious injury or mortality will
occur as a result of ADOT's planned activity given the nature of the
activity, even in the absence of required mitigation. Further, no take
by Level A harassment is anticipated for Pacific white-sided dolphin,
killer whale, or humpback whale, due to the likelihood of occurrence
and/or required mitigation measures. As stated in the mitigation
section, ADOT will implement shutdown zones that equal or exceed many
of the Level A harassment isopleths shown in Table 12. Take by Level A
harassment is authorized for some species (Steller sea lions, harbor
seals, harbor porpoises, Dall's porpoises, and minke whales) to account
for the potential that an animal could enter and remain within the area
between a Level A harassment zone and the shutdown zone for a duration
long enough to be taken by Level A harassment, and in some cases, to
account for the possibility that an animal could enter a shutdown zone
without detection given the various obstructions along the shoreline,
and remain in the Level A harassment zone for a duration long enough to
be taken by Level A harassment before being observed and a shutdown
occurring. Any take by Level A harassment is expected to arise from, at
most, a small degree of PTS because animals would need to be exposed to
higher levels and/or longer duration than are expected to occur here in
order to incur any more than a small degree of PTS. Additionally, and
as noted previously, some subset of the individuals that are
behaviorally harassed could also simultaneously incur some small degree
of TTS for a short duration of time. Because of the small degree
anticipated, though, any PTS or TTS potentially incurred here is not
expected to adversely impact individual fitness, let alone annual rates
of recruitment or survival.
For all species and stocks, take will occur within a limited,
confined area (adjacent to the project site) of the stock's range. Take
by Level A harassment and Level B harassment will be reduced to the
level of least practicable adverse impact through use of mitigation
measures described herein. Further the amount of take authorized is
small when compared to stock abundance.
Behavioral responses of marine mammals to pile driving, pile
removal, and DTH at the sites in Tongass Narrows are expected to be
mild, short term, and temporary. Marine mammals within the Level B
harassment zones may not show any visual cues they are disturbed by
activities or they could become alert, avoid the area, leave the area,
or display other mild responses that are not observable such as changes
in vocalization patterns. Given that pile driving, pile removal, and
DTH will occur for only a portion of the project's duration and often
on nonconsecutive days, any harassment will be temporary. Additionally,
many of the species present in Tongass Narrows or Clarence Strait will
only be present temporarily based on seasonal patterns or during
transit between other habitats. These temporarily present species will
be exposed to even smaller periods of noise-generating activity,
further decreasing the impacts.
For all species except humpback whales, there are no known
Biologically Important Areas (BIAs) near the project zone that will be
impacted by ADOT's planned activities. For humpback whales, the whole
of Southeast Alaska is a seasonal BIA from spring through late fall
(Ferguson et al. 2015), however, Tongass Narrows and Clarence Strait
are not important portions of this habitat due to development and human
presence. Tongass Narrows is also a small passageway and represents a
very small portion of the total available habitat. Also, while
southeast Alaska is considered an important area for feeding humpback
whales between March and May (Ellison et al. 2012), it is not currently
designated as critical habitat for humpback whales (86 FR 21082; April
21, 2021).
More generally, there are no known calving or rookery grounds
within the project area, but anecdotal evidence from local experts
shows that marine mammals are more prevalent in Tongass Narrows and
Clarence Strait during spring and summer associated with feeding on
aggregations of fish, meaning the area may play a role in foraging.
Because ADOT's activities could occur during any season, takes may
occur during important feeding times. However, the project area
represents a small portion of available foraging habitat and impacts on
marine mammal feeding for all species, including humpback whales,
should be minimal.
Any impacts on marine mammal prey that occur during ADOT's planned
activity will have, at most, short-term effects on foraging of
individual marine mammals, and likely no effect on the populations of
marine mammals as a whole. Indirect effects on marine mammal prey
during the construction are expected to be minor, and these
[[Page 15407]]
effects are unlikely to cause substantial effects on marine mammals at
the individual level, with no expected effect on annual rates of
recruitment or survival.
In addition, it is unlikely that minor noise effects in a small,
localized area of habitat will have any effect on the reproduction or
survival of any individuals, much less the stocks' annual rates of
recruitment or survival. In combination, we believe that these factors,
as well as the available body of evidence from other similar
activities, demonstrate that the potential effects of the specified
activities will have only minor, short-term effects on individuals. The
specified activities are not expected to impact rates of recruitment or
survival and will, therefore, not result in population-level impacts.
In summary, and as described above, the following factors primarily
support our 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 serious injury or mortality is anticipated or
authorized;
Take by Level A harassment of Pacific white-sided dolphin,
killer whale, and humpback whale is not anticipated or authorized;
ADOT will implement mitigation measures including soft-
starts for impact pile driving and shutdown zones to minimize the
numbers of marine mammals exposed to injurious levels of sound, and to
ensure that any take by Level A harassment is, at most, a small degree
of PTS;
The intensity of anticipated takes by Level B harassment
is relatively low for all stocks and will not be of a duration or
intensity expected to result in impacts on reproduction or survival;
The only known area of specific biological importance
covers a broad area of southeast Alaska for humpback whales, and the
project area is a very small portion of that BIA. No other known areas
of particular biological importance to any of the affected species or
stocks are impacted by the activity, including ESA-designated critical
habitat;
The project area represents a very small portion of the
available foraging area for all potentially impacted marine mammal
species and stocks and anticipated habitat impacts are minor; and
Monitoring reports from similar work in Tongass Narrows
have documented little to no effect on individuals of the same species
impacted by the specified activities.
Based on the analysis contained herein of the likely effects of the
specified activity on marine mammals and their habitat, and taking into
consideration the implementation of the required monitoring and
mitigation measures, NMFS finds that the total marine mammal take from
the planned activity 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. When the predicted number of
individuals to be taken is fewer than one third of the species or stock
abundance, the take is considered to be of small numbers. Additionally,
other qualitative factors may be considered in the analysis, such as
the temporal or spatial scale of the activities.
The instances of take NMFS authorized are below one third of the
estimated stock abundance for all stocks (see Table 14). The number of
animals that we expect to authorize to be taken from these stocks is
considered small relative to the relevant stocks' abundances even if
each estimated taking occurred to a new individual, which is an
unlikely scenario. Some individuals may return multiple times in a day,
but PSOs will count them as separate takes if they cannot be
individually identified.
The Alaska stock of Dall's porpoise has no official NMFS abundance
estimate for this area, as the most recent estimate is greater than
eight years old. The most recent estimate was 13,110 animals for just a
portion of the stock's range. Therefore, the 227 authorized takes of
this stock clearly represent small numbers of this stock.
Likewise, the Southeast Alaska stock of harbor porpoise has no
official NMFS abundance estimate as the most recent estimate is greater
than 8 years old. The most recent estimate was 11,146 animals (Muto et
al. 2021) and it is highly unlikely this number has drastically
declined. Therefore, the 32 authorized takes of this stock clearly
represent small numbers of this stock.
There is no current or historical estimate of the Alaska minke
whale stock, but there are known to be over 1,000 minke whales in the
Gulf of Alaska (Muto et al. 2018), so the 3 authorized takes clearly
represent small numbers of this stock. Additionally, the range of the
Alaska stock of minke whales is extensive, stretching from the Canadian
Pacific coast to the Chukchi Sea, and ADOT's project area impacts a
small portion of this range.
Based on the analysis contained herein of the planned activity
(including the required mitigation and monitoring measures) and the
anticipated take of marine mammals, NMFS 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
In order to issue an IHA, NMFS must find that the specified
activity will not have an ``unmitigable adverse impact'' on the
subsistence uses of the affected marine mammal species or stocks by
Alaska Natives. NMFS has defined ``unmitigable adverse impact'' in 50
CFR 216.103 as an impact resulting from the specified activity: (1)
That is likely to reduce the availability of the species to a level
insufficient for a harvest to meet subsistence needs by: (i) Causing
the marine mammals to abandon or avoid hunting areas; (ii) Directly
displacing subsistence users; or (iii) Placing physical barriers
between the marine mammals and the subsistence hunters; and (2) That
cannot be sufficiently mitigated by other measures to increase the
availability of marine mammals to allow subsistence needs to be met.
Harbor seals are the marine mammal species most regularly harvested
for subsistence by households in Ketchikan and Saxman (a community a
few miles south of Ketchikan, on the Tongass Narrows). Eighty harbor
seals were harvested by Ketchikan residents in 2007, which ranked
fourth among all communities in Alaska that year for harvest of harbor
seals. Thirteen harbor seals were harvested by Saxman residents in
2007. In 2008, two Steller sea lions were harvested by Ketchikan-based
subsistence hunters, but this is the only record of sea lion harvest by
residents of either Ketchikan or Saxman. In 2012, the community of
Ketchikan had an estimated subsistence take of 22 harbor seals and 0
Steller sea lion (Wolf et al. 2013). NMFS is not aware of more recent
data. Hunting usually occurs in October and November (ADF&G 2009), but
there are also records of relatively high harvest in May (Wolfe et al.
2013). The Alaska Department of Fish and
[[Page 15408]]
Game (ADF&G) has not recorded harvest of cetaceans from Ketchikan or
Saxman (ADF&G 2018).
All project activities will take place within the industrial area
of Tongass Narrows immediately adjacent to Ketchikan where subsistence
activities do not generally occur. Both the harbor seal and the Steller
sea lion may be temporarily displaced from the project area. The
project will also not have an adverse impact on the availability of
marine mammals for subsistence use at locations farther away, where
these construction activities are not expected to take place. Some
minor, short-term harassment of the harbor seals could occur, but given
the information above, we do not expect such harassment to have effects
on subsistence hunting activities.
Based on the description of the specified activity and the required
mitigation and monitoring measures, NMFS has determined that there will
not be an unmitigable adverse impact on subsistence uses from ADOT's
planned activities.
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 evaluate our proposed action (i.e., the issuance of an IHA)
and alternatives with respect to potential impacts on the human
environment. This action is consistent with categories of activities
identified in Categorical Exclusion B4 of the Companion Manual for NAO
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 determined
that this action qualifies to be categorically excluded from further
NEPA review.
Endangered Species Act
Section 7(a)(2) of the Endangered Species Act of 1973 (ESA: 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' Office of Protected Resources (OPR) consults internally whenever
we propose to authorize take for endangered or threatened species, in
this case with NMFS' Alaska Regional Office (AKRO).
NMFS OPR is proposing to authorize take of the Central North
Pacific stock of humpback whales, of which a portion belong to the
Mexico DPS of humpback whales, which are ESA-listed. On February 6,
2019, NMFS AKRO completed consultation with NMFS for the Tongass
Narrows Project and issued a Biological Opinion. Reinitiation of formal
consultation was required to analyze changes to the action that were
not considered in the February 2019 opinion (PCTS# AKR-2018-9806/ECO#
AKRO-2018-01287). The original opinion considered the effects of only
one project component being constructed at a time and did not analyze
potential effects of concurrent pile driving that may cause effects to
the listed species that were not considered in the original opinion;
therefore, reinitiation of formal consultation was required. NMFS' AKRO
issued a revised Biological Opinion to NMFS' OPR on December 19, 2019
that concluded that issuance of IHAs to ADOT is not likely to
jeopardize the continued existence of Mexico DPS humpback whales. The
effects of this Federal action were adequately analyzed in NMFS'
Endangered Species Act (ESA) Section 7(a)(2) Biological Opinion for
Construction of the Tongass Narrows Project (Gravina Access), revised
December 19, 2019, which concluded that the take NMFS proposes to
authorize through this IHA would not jeopardize the continued existence
of any endangered or threatened species or destroy or adversely modify
any designated critical habitat. NMFS has determined that issuance of
this IHA does not require reinitiation of the December 2019 Biological
Opinion.
Authorization
NMFS has issued an IHA to ADOT for the potential harassment of
small numbers of eight marine mammal species incidental to construction
of four facilities in the channel between Gravina Island and
Revillagigedo (Revilla) Island in Ketchikan, Alaska, that includes the
previously explained mitigation, monitoring and reporting requirements.
Dated: March 11, 2022.
Kimberly Damon-Randall,
Director, Office of Protected Resources, National Marine Fisheries
Service.
[FR Doc. 2022-05561 Filed 3-17-22; 8:45 am]
BILLING CODE 3510-22-P
