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Notice2022-05561

Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to Ferry Berth Improvements in Tongass Narrows in Ketchikan, Alaska

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Published

March 18, 2022

Effective

March 5, 2022

Issuing agencies

Commerce DepartmentNational Oceanic and Atmospheric Administration

Abstract

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.

Full Text

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<title>Federal Register, Volume 87 Issue 53 (Friday, March 18, 2022)</title>
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[Federal Register Volume 87, Number 53 (Friday, March 18, 2022)]
[Notices]
[Pages 15387-15408]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2022-05561]

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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.

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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: <a href="https://www.fisheries.noaa">https://www.fisheries.noaa</a>.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; <a href="https://www.fisheries.noaa">https://www.fisheries.noaa</a> .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 (<a href="https://www.fisheries.noaa">https://www.fisheries.noaa</a> .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: <a href="https://www.fisheries.noaa">https://www.fisheries.noaa</a>.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: <a href="https://www.fisheries.noaa">https://www.fisheries.noaa</a>.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 (<a href="https://www.fisheries.noaa">https://www.fisheries.noaa</a> .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
<a href="https://www.fisheries.noaa">https://www.fisheries.noaa</a>.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:
<bullet> 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);
<bullet> 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;
<bullet> 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;
<bullet> 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;
<bullet> 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;
<bullet> 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;
<bullet> 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;
<bullet> 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;
<bullet> 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;
<bullet> 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);
<bullet> 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;
<bullet> 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;
<bullet> 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;
<bullet> 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.
<bullet> 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
<bullet> 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:
<bullet> 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;
<bullet> 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.
<bullet> 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:
<bullet> Occurrence of marine mammal species or stocks in the area
in which take is anticipated (e.g., presence, abundance, distribution,
density).
<bullet> 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).
<bullet> Individual marine mammal responses (behavioral or
physiological) to acoustic stressors (acute, chronic, or cumulative),
other stressors, or cumulative impacts from multiple stressors.
<bullet> How anticipated responses to stressors impact either: (1)
Long-term fitness and survival of individual marine mammals; or (2)
populations, species, or stocks.
<bullet> Effects on marine mammal habitat (e.g., marine mammal prey
species, acoustic habitat, or other important physical components of
marine mammal habitat).
<bullet> Mitigation and monitoring effectiveness.

Visual Monitoring

Monitoring must be conducted by qualified, NMFS-approved PSOs, in
accordance with the following:
<bullet> 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
<bullet> 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:
<bullet> Ability to conduct field observations and collect data
according to assigned protocols;
<bullet> Experience or training in the field identification of
marine mammals, including the identification of behaviors;
<bullet> Sufficient training, orientation, or experience with the
construction operation to provide for personal safety during
observations;
<bullet> 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
<bullet> 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:
<bullet> Dates and times (begin and end) of all marine mammal
monitoring;
<bullet> 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);
<bullet> PSO locations during marine mammal monitoring;
<bullet> 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;
<bullet> 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);
<bullet> Number of marine mammals detected within the harassment
zones and shutdown zones, by species;
<bullet> Table summarizing any incidents resulting in take of ESA-
listed species;
<bullet> 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;
<bullet> Description of other human activity within each monitoring
period;
<bullet> Description of any deviation from initial proposal in pile
numbers, pile types, average driving times, etc.;
<bullet> Brief description of any impediments to obtaining reliable
observations during construction period;
<bullet> Description of any impediments to complying with these
mitigation measures; and
<bullet> 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)
(<a href="/cdn-cgi/l/email-protection#79292b57302d2957341617100d160b10171e2b1c09160b0d0a3917161818571e160f"><span class="__cf_email__" data-cfemail="b3e3e19dfae7e39dfedcdddac7dcc1daddd4e1d6c3dcc1c7c0f3dddcd2d29dd4dcc5">[email&#160;protected]</span></a>), 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:
<bullet> Time, date, and location (latitude/longitude) of the first
discovery (and updated location information if known and applicable);
<bullet> Species identification (if known) or description of the
animal(s) involved;
<bullet> Condition of the animal(s) (including carcass condition if
the animal is dead);
<bullet> Observed behaviors of the animal(s), if alive;
<bullet> If available, photographs or video footage of the
animal(s); and
<bullet> 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:
<bullet> No serious injury or mortality is anticipated or
authorized;
<bullet> Take by Level A harassment of Pacific white-sided dolphin,
killer whale, and humpback whale is not anticipated or authorized;
<bullet> 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;
<bullet> 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;
<bullet> 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;
<bullet> 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
<bullet> 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

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