Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to the Alaska Department of Transportation and Public Facilities Angoon Ferry Terminal Modification Project in Angoon, Alaska, 13463-13485 [2025-04902]

Agencies

• DEPARTMENT OF COMMERCE
• National Oceanic and Atmospheric Administration

[Federal Register Volume 90, Number 55 (Monday, March 24, 2025)]
[Notices]
[Pages 13463-13485]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2025-04902]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

[RTID 0648-XE746]


Takes of Marine Mammals Incidental to Specified Activities; 
Taking Marine Mammals Incidental to the Alaska Department of 
Transportation and Public Facilities Angoon Ferry Terminal Modification 
Project in Angoon, Alaska

AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and 
Atmospheric Administration (NOAA), Commerce.

ACTION: Notice; proposed incidental harassment authorization; request 
for comments on proposed authorization and possible renewal.

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SUMMARY: NMFS has received a request from the Alaska Department of 
Transportation and Public Facilities (ADOT&PF) for authorization to 
take marine mammals incidental to Angoon Ferry Terminal Modification 
Project in Angoon, Alaska. Pursuant to the Marine Mammal Protection Act 
(MMPA), NMFS is requesting comments on its proposal to issue an 
incidental harassment authorization (IHA) to incidentally take marine 
mammals during the specified activities. NMFS is also requesting 
comments on a possible one-time, 1-year renewal that could be issued 
under certain circumstances and if all requirements are met, as 
described in Request for Public Comments at the end of this notice. 
NMFS will consider public comments prior to making any final decision 
on the issuance of the requested MMPA authorization and agency 
responses will be summarized in the final notice of our decision.

DATES: Comments and information must be received no later than April 
23, 2025.

ADDRESSES: Comments should be addressed to Jolie Harrison, Chief, 
Permits and Conservation Division, Office of Protected Resources, 
National Marine Fisheries Service and should be submitted via email to 
[email protected]. Electronic copies of the application and supporting 
documents, as well as a list of the references cited in this document, 
may be obtained online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities. In case of problems accessing these documents, please call 
the contact listed below.
    Instructions: NMFS is not responsible for comments sent by any 
other method,

[[Page 13464]]

to any other address or individual, or received after the end of the 
comment period. Comments, including all attachments, must not exceed a 
25-megabyte file size. All comments received are a part of the public 
record and will generally be posted online at https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act without change. All personal identifying 
information (e.g., name, address) voluntarily submitted by the 
commenter may be publicly accessible. Do not submit confidential 
business information or otherwise sensitive or protected information.

FOR FURTHER INFORMATION CONTACT: Leah Davis, Office of Protected 
Resources, NMFS, (301) 427-8401.

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 proposed or, if the taking is limited to harassment, a notice of a 
proposed IHA is provided to the public for review.
    Authorization for incidental takings shall be granted if NMFS finds 
that the taking will have a negligible impact on the species or 
stock(s) and will not have an unmitigable adverse impact on the 
availability of the species or stock(s) for taking for subsistence uses 
(where relevant). Further, NMFS must prescribe the permissible methods 
of taking and other ``means of effecting the least practicable adverse 
impact'' on the affected species or stocks and their habitat, paying 
particular attention to rookeries, mating grounds, and areas of similar 
significance, and on the availability of the species or stocks for 
taking for certain subsistence uses (referred to in shorthand as 
``mitigation''); and requirements pertaining to the monitoring and 
reporting of the takings. The definitions of all applicable MMPA 
statutory terms used above are included in the relevant sections below 
and can be found in section 3 of the MMPA (16 U.S.C. 1362) and NMFS 
regulations at 50 CFR 216.103.

National Environmental Policy Act

    To comply with the National Environmental Policy Act of 1969 (NEPA; 
42 U.S.C. 4321 et seq.) and NOAA Administrative Order (NAO) 216-6A, 
NMFS must review our proposed action (i.e., the issuance of an IHA) 
with respect to potential impacts on the human environment.
    This action is consistent with categories of activities identified 
in Categorical Exclusion B4 (IHAs with no anticipated serious injury or 
mortality) 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 preliminarily determined 
that the issuance of the proposed IHA qualifies to be categorically 
excluded from further NEPA review.

Summary of Request

    On September 6, 2024, NMFS received a request from ADOT&PF for an 
IHA to take marine mammals incidental to pile driving (installation and 
removal) associated with construction for one ferry terminal in Angoon, 
Alaska. Following NMFS' review of the application, ADOT&PF submitted 
revised versions on November 6, 2024, November 12, 2024, November 26, 
2024, and December 23, 2024. A final revised application was submitted 
on January 6, 2025 and the application was deemed adequate and complete 
on January 27, 2025. The ADOT&PF request is for take of eight species 
(12 stocks) by Level B harassment and, for a subset five of these 
species, Level A harassment. Neither ADOT&PF nor NMFS expect serious 
injury or mortality to result from this activity and, therefore, an IHA 
is appropriate.

Description of Proposed Activity

Overview

    ADOT&PF is proposing to make improvements to Angoon Ferry Terminal 
within Killisnoo Harbor in Angoon, Alaska. The existing Angoon Ferry 
terminal was originally designed for the Alaska Marine Highway System 
fast ferries and motor vessels but ADOT&PF is in the process of 
replacing these aging vessels with longer and wider Alaska Class 
Ferries. Ferry replacement requires mooring dolphin rearrangement to 
accommodate these larger vessels as well as upgrades to the lift system 
from electric to hydraulic actuators for more reliable operations. 
Construction would occur on approximately 143 non-consecutive in-water 
work days over the course of 1 year. The proposed activities that have 
the potential to take marine mammals, by Level A and level B 
harassment, include down-the-hole drilling (DTH) of rock sockets and 
tension anchors, vibratory installation and removal of temporary steel 
pipe piles, vibratory and impact installation of permanent steel pipe 
piles, and vibratory removal of permanent piles (in cases where piles 
cannot be removed with direct pull methods).

Dates and Duration

    ADOT&PF anticipates the project would require 143 non-consecutive -
in water days of pile installation and removal over the course of 1 
year. The effective date of the IHA, if issued, would be from May 1, 
2026 through April 30, 2027.

Specific Geographic Region

    The Angoon Ferry Terminal Modifications Project is located in 
Killisnoo Harbor in Angoon, Alaska as shown in figure 1. Angoon is a 
small southeast Alaskan village and the only permanent settlement on 
Admiralty Island. The ferry terminal is approximately 2 miles (3.2 
kilometers (km)) south of Angoon's city center. The ferry terminal is 
adjacent to the City of Angoon's deep draft dock serving as the 
community's fuel supply operation, and other marine facilities in 
Angoon include a small boat harbor and seaplane base on Kootznahoo 
Inlet. Killisnoo Harbor is approximately 1 mile (1.6 km) wide and is 
situated between the west shore of Admiralty Island on the eastern side 
of Chatham Strait, which is one of the most extensive inside passages 
in Southeast Alaska. Water depths in the harbor are generally 150 feet 
(45.7 meters (m)) or shallower.
BILLING CODE 3510-22-P

[[Page 13465]]

[GRAPHIC] [TIFF OMITTED] TN24MR25.000

BILLING CODE 3510-22-C

[[Page 13466]]

Detailed Description of the Specified Activity

    ADOT&PF is proposing to upgrade the existing Angoon Ferry Terminal 
to accommodate the new larger Alaska Class Vessel berthing. Work would 
include installation of three new floating fender dolphins (N4, N8, and 
N10), replacement of a mooring dolphin (S3), and modification of an 
existing dolphin (N7, to be renamed N9) to be an ultra-high molecular 
weight polyethylene panel fender pile, as well as some other above-
water work.
    The N4 floating fender dolphin would be comprised of one 30 inch 
(70 centimeters (cm)) steel pipe fender pile, two 24 inch (61 cm) 
vertical steel pipe piles, and two 24 inch (61 cm) batter piles. The N8 
and N10 floating fender pile dolphins would each consist of one fender 
pile, two vertical piles, and two batter piles, all 30-in steel pipe 
piles. S3 mooring dolphin replacement would include removal and 
replacement of two 20 inch (51 cm) batter piles and potentially one 24 
inch (61 cm) steel pipe pile. Tension anchors for the S3 mooring dock 
piles would also be cut at the mudline. ADOT&PF would also install and 
remove 16 temporary steel pipe piles up to 24 inch (61 cm) in diameter 
using a vibratory hammer as part of the construction process. ADOT&PF 
anticipates that pile removal would occur via direct pull, cutting, 
clipping, or other above water activities when feasible, but may use a 
vibratory hammer to extract piles if necessary. In addition to 
vibratory and impact pile driving, ADOT&PF may install rock sockets and 
tension anchors at some locations. Table 1 includes the total number of 
piles of each type and the proposed construction method.
    The construction crew may use a single installation method for 
multiple piles on a single day or find other efficiencies to increase 
production; the anticipated ranges of possible values are provided in 
table 1. All of the construction activities described above have the 
potential to result in both Level A and Level B behavioral harassment 
of marine mammals.
    Existing dolphin N7 (to be renamed N9) would be modified by cutting 
and replacing a portion of the pile about 10 feet (3.0 m) above high 
tide line. Other out-of-water work would include converting the 
existing electrical actuated bridge and apron lift system to a 
hydraulic actuated system; installing new hydraulic actuators, 
hydraulic power unit, and associated electrical components; and making 
improvements to the dock's transfer bridge and other uplands 
components. Modification of dolphin N7 and the other out-of-water work 
described here is not anticipated to result in take of marine mammal, 
and therefore, these activities are not discussed further in this 
document.

     Table 1-- Number and Type of Piles To Be Installed and Removed by Impact and Vibratory Driving and DTH
----------------------------------------------------------------------------------------------------------------
                                                                                      Number of     Max days of
             Activity                         Method               Pile diameter        piles        activity
----------------------------------------------------------------------------------------------------------------
Installation.....................  Vibratory..................  24 inch (61 cm)               16              16
                                                                 Steel Piles.
                                                                20 or 24 inch (51              7               7
                                                                 or 61 cm) Steel
                                                                 Piles.
                                                                30 inch (76 cm)               11              11
                                                                 Steel Piles.
Removal..........................  Vibratory..................  20 inch (51 cm)                2               2
                                                                 Steel Piles.
                                                                24 inch (61 cm)               17              17
                                                                 Steel Piles.
Installation.....................  Impact.....................  20 or 24 inch (51              7              14
                                                                 or 61 cm) Steel
                                                                 Piles.
                                                                30 inch (76 cm)               11              22
                                                                 Steel Piles.
8 inch (20 cm) tension anchor      DTH........................  ...................            7              21
 (for 24 inch (61 cm) piles).
8 inch (20 cm) tension anchor      DTH........................  ...................            8              24
 (for 30 inch (76 cm) piles).
Rock socket (for 30 inch (76 cm)   DTH........................  ...................            3               9
 piles).
----------------------------------------------------------------------------------------------------------------
Proposed mitigation, monitoring, and reporting measures are described in detail later in this document (please
  see Proposed Mitigation and Proposed Monitoring and Reporting).

Description of Marine Mammals in the Area of Specified Activities

    Sections 3 and 4 of the application summarize available information 
regarding status and trends, distribution and habitat preferences, and 
behavior and life history of the potentially affected species. NMFS 
fully considered all of this information, and we refer the reader to 
these descriptions, instead of reprinting the information. Additional 
information regarding population trends and threats may be found in 
NMFS' Stock Assessment Reports (SARs; https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments) and 
more general information about these species (e.g., physical and 
behavioral descriptions) may be found on NMFS' website (https://www.fisheries.noaa.gov/find-species).
    Table 2 lists all species or stocks for which take is expected and 
proposed to be authorized for the activities at the Angoon Ferry 
Terminal, 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. 
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 serious 
injury or mortality is anticipated or proposed to be authorized here, 
PBR and annual serious injury and mortality (M/SI) from anthropogenic 
sources are included here as gross indicators of the status of the 
species or stocks 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' Alaska and Pacific SARs. All values presented in table 2 are the 
most recent available at the time of publication and are available 
online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments.

[[Page 13467]]



                                         Table 2--Species \a\ With Estimated Take From the Specified Activities
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                         ESA/ MMPA status;   Stock abundance (CV,
             Common name                  Scientific name               Stock             strategic (Y/N)      Nmin, most recent       PBR     Annual M/
                                                                                                \b\          abundance survey) \c\               SI \d\
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                 Order Artiodactyla--Cetacea--Mysticeti (baleen whales)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Balaenopteridae (rorquals):
    Humpback Whale..................  Megaptera novaeangliae.  Mainland Mexico-CA/OR/   T, D, Y             3,477 (0.101, 3,185,           43         22
                                                                WA.                                          2018).
                                                               Hawai[revaps]i.........  -, -, N             11,278 (0.56, 7,265,          127      27.09
                                                                                                             2020).
    Minke Whale.....................  Balaenoptera             Alaska.................  -, -, N             N/A (N/A, N/A, N/A)           UND          0
                                       acutorostrata.                                                        \e\.
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                  Odontoceti (toothed whales, dolphins, and porpoises)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Delphinidae:
    Killer whale....................  Orcinus orca...........  Eastern North Pacific    -, -, N             1,920 (N/A, 1,920,             19        1.3
                                                                Alaska Resident.                             2019) \f\.
                                                               Eastern Northern         -, -, N             302 (N/A, 302, 2018)          2.2        0.2
                                                                Pacific Northern                             \f\.
                                                                Resident.
                                                               West Coast Transient...  -, -, N             349 (N/A, 349, 2018)          3.5        0.4
                                                                                                             \g\.
    Pacific White-Sided Dolphin.....  Lagenorhynchus           N Pacific..............  -, -, N             26,880 (N/A, N/A,             UND          0
                                       obliquidens.                                                          1990).
Family Phocoenidae (porpoises):
Dall's Porpoise.....................  Phocoenoides dalli.....  Alaska.................  -, -, N             UND (UND, UND, 2015)          UND         37
                                                                                                             \h\.
Harbor Porpoise.....................  Phocoena phocoena......  Northern Southeast       -, -, N             1,619 (0.26, 1,250,            13        5.6
                                                                Alaska Inland Waters                         2019).
                                                                \i\.
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                               Order Carnivora--Pinnipedia
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Otariidae (eared seals and
 sea lions):
Steller Sea Lion....................  Eumetopias jubatus.....  Western................  E, D, Y             49,837 (N/A, 49,837,          299        267
                                                                                                             2022) \j\.
                                                               Eastern................  -, -, N             36,308 (N/A, 36,308,        2,178       93.2
                                                                                                             2022) \k\.
Family Phocidae (earless seals):
Harbor Seal.........................  Phoca vitulina.........  Sitka/Chatham Strait...  -, -, N             13,289 (N/A, 11,883,          356         77
                                                                                                             2015.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Information on the classification of marine mammal species can be found on the web page for The Society for Marine Mammalogy's Committee on Taxonomy
  (https://marinemammalscience.org/science-and-publications/list-marine-mammal-species-subspecies/).
\b\ 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.
\c\ NMFS marine mammal SARs online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports-region.
  CV is coefficient of variation; Nmin is the minimum estimate of stock abundance. In some cases, CV is not applicable.
\d\ These values, found in NMFS's SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined (e.g.,
  commercial fisheries, ship strike). Annual M/SI often cannot be determined precisely and is in some cases presented as a minimum value or range. A CV
  associated with estimated mortality due to commercial fisheries is presented in some cases.
\e\ Reliable population estimates are not available for this stock. Please see Friday et al. (2013) and Zerbini et al. (2006) for additional information
  on numbers of minke whales in Alaska.
\f\ Nest is based upon counts of individuals identified from photo-ID catalogs.
\g\ Nest is based upon count of individuals identified from photo-ID catalogs in analysis of a subset of data from 1958-2018.
\h\ The best available abundance estimate is likely an underestimate for the entire stock because it is based upon a survey that covered only a small
  portion of the stock's range.
\i\ New stock split from Southeast Alaska stock.
\j\ Nest is best estimate of counts, which have not been corrected for animals at sea during abundance surveys. Estimates provided are for the United
  States only. The overall Nmin is 73,211 and overall PBR is 439.
\k\ Nest is best estimate of counts, which have not been corrected for animals at sea during abundance surveys. Estimates provided are for the United
  States only.

    As indicated above, all 8 species (with 12 managed stocks) in table 
2 temporally and spatially co-occur with the activity to the degree 
that take is reasonably likely to occur. All species that could 
potentially occur in the proposed action area are included in table 3 
of the IHA application. While gray whales have been documented in the 
area, the temporal and/or spatial occurrence of these species is such 
that take is not expected to occur, and they are not discussed further 
beyond the explanation provided here. Gray whales are considered to be 
very rare with no local knowledge of sightings and no sightings in 
recent years have been reported in recent years.
    In addition, the Northern sea otter (Enhydra lutris kenyoni) may be 
found in the project area. However, sea otters are managed by the U.S. 
Fish and Wildlife Service and are not considered further in this 
document.

Humpback Whale

    The Mainland Mexico-CA/OR/WA and Hawaii stocks of humpback whale 
occur in the project area. Wild et al. (2023) identified Northern 
Chatham Strait as a Biologically Important Area (BIA) for humpback 
whales for feeding during the months of May through October, with an 
importance score of two (indicating an area of moderate importance), an 
intensity score of two (indicating an area of moderate comparative 
significance) and a data support score of three (highest relative 
confidence in the available supporting data). ADOT&PF ferry Captain of 
the M/V LeConte routinely transits the area and reports that humpback 
whales are frequently observed in Chatham Strait and the project area.

Minke Whale

    Minke whale surveys in Southeast Alaska have consistently 
identified individuals throughout inland waters in low numbers 
(Dahlheim et al. 2009). All sightings were of single minke whales, 
except for a single sighting of multiple minke whales. Surveys took 
place in spring, summer, and fall, and minke whales were present in low 
numbers in

[[Page 13468]]

all seasons and years.Little is known about minke whale abundance and 
distribution in the project area as there have been no systematic 
studies conducted on the species in or near Killsnoo Harbor. Surveys 
throughout southeast Alaska between 1991 and 2007 recorded minke whales 
infrequently, but noted a wide variety of habitat types used throughout 
all inland waters and little seasonal variation. During these surveys, 
minke whales were observed in the Chatham Strait during the fall, 
approximately 19 km north of the proposed action area. Most minke 
whales observed during the surveys were individual animals (Dahlheim et 
al., 2009). Therefore, minke whales are expected to be rare near the 
action area.

Killer Whale

    Killer whales occur throughout the North Pacific and along the 
entire Alaska coast, in British Columbia and Washington inland 
waterways, and along the outer coasts of Washington, Oregon, and 
California. Of the eight recognized killer whale stocks, only the 
Eastern North Pacific Alaska Resident, Eastern Northern Pacific 
Northern Resident, and West Coast Transient stocks are expected to 
occur in the project area. Transient killer whales often occur in long-
term stable social units (pods) of 1 to 16 whales. Average pod sizes in 
Southeast Alaska were 6.0 in spring, 5.0 in summer, and 3.9 in fall. 
Pod sizes of transient whales are generally smaller than those of 
resident social groups. Resident killer whales occur in larger pods, 
ranging from 7 to 70 whales that are seen in association with one 
another more than 50 percent of the time (Dahlheim et al., 2009; NMFS 
2016b). In Southeast Alaska, resident killer whale mean pod size was 
approximately 21.5 in spring, 32.3 in summer, and 19.3 in fall 
(Dahlheim et al., 2009).
    Surveys between 1991 and 2007 encountered resident killer whales 
during all seasons throughout southeast Alaska. Both residents and 
transients were common in a variety of habitats and all major 
waterways, including protected bays and inlets. The authors found 
strong seasonal variation in abundance or distribution of killer whales 
was not present, but there was substantial variability between years 
(Dahlheim et al., 2009). Systematic surveys of killer whales have not 
been conducted in Killisnoo Harbor, Hood Bay, or the Chatham Strait. 
Although killer whales are common throughout southeast Alaska, they are 
expected to occur infrequently in the project area.

Pacific White-Sided Dolphin

    Pacific white-sided dolphins are a pelagic species inhabiting 
temperate waters of the North Pacific Ocean and along the coasts of 
California, Oregon, Washington, and Alaska (Muto et al., 2021). Despite 
their distribution mostly in deep, offshore waters, they also occur 
over the continental shelf and near shore waters, including inland 
waters of Southeast Alaska (Ferrero and Walker 1996). Dalheim et al. 
(2009) frequently encountered Pacific white-sided dolphin in Clarence 
Strait with significant differences in mean group size, but overall 
encounters were rare enough to limit the seasonality investigation to a 
qualitative note that spring featured the highest number of animals 
observed. These observations were located most typically in open strait 
environments, near the open ocean.
    In southeast Alaska, Pacific white-sided dolphin occur in groups of 
2 to 153 individuals, but are most commonly seen in groups of 23-26 
individuals (Dahlheim et al., 2009). However, animals have also been 
observed in groups with over 1,000 individuals (Stacey and Baird 1991). 
Although estimated to be uncommon in Killisnoo Harbor and Hood Bay, 
Pacific white-sided are reasonably likely to occur during the proposed 
construction activities.

Dall's Porpoise

    Dall's porpoise is found in temperate to subarctic waters of the 
North Pacific and adjacent seas. They are widely distributed across the 
North Pacific over the continental shelf and slope waters, and over 
deep (greater than 2,500 m) oceanic waters (Friday et al., 2012; Friday 
et al., 2013).

Harbor Porpoise

    The harbor porpoise is common in coastal waters. Individuals 
frequently occur in coastal waters of southeast Alaska and are observed 
most frequently in waters less than 107 m deep (Dahlheim et al., 2009). 
The Northern Southeast Alaska Inland Waters stock occurs in Cross 
Sound, Glacier Bay, Icy Strait, Chatham Strait, Frederick Sound, 
Stephens Passage, Lynn Canal, and adjacent inlets (Young et al., 2023).

Steller Sea Lion

    The western distinct population segment (DPS) of Steller sea lion 
breeds on rookeries located west of 144 degrees W in Alaska and Russia, 
and the eastern DPS breeds on rookeries in southeast Alaska through 
California. Movement occurs between the western and eastern DPSs of 
Steller sea lions, and increasing numbers of individuals from the 
western DPS have been seen in southeast Alaska in recent years (Muto et 
al., 2020; Fritz et al., 2016). However, the proposed project area is 
outside of core mixing zones for western and eastern DPS Steller sea 
lions, thus animals in this area are expected to primarily be from the 
eastern DPS (Hastings et. al., 2020).

Harbor Seal

    Harbor seals are common in the coastal and inside waters of the 
project areas. Harbor seals in Alaska are typically non-migratory with 
local movements attributed to factors such as prey availability, 
weather, and reproduction (Scheffer and Slipp, 1944; Bigg, 1969; 
Hastings et al., 2004). Harbor seals haul out of the water periodically 
to rest, give birth, and nurse their pups.

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. 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, 2019) recommended that marine mammals be divided into hearing 
groups based on directly measured (behavioral or auditory evoked 
potential techniques) or estimated hearing ranges (behavioral response 
data, anatomical modeling, etc.). Generalized hearing ranges were 
chosen based on the ~65 decibel (dB) threshold from composite 
audiograms, previous analyses in NMFS (2018), and/or data from Southall 
et al. (2007) and Southall et al. (2019). We note that the names of two 
hearing groups and the generalized hearing ranges of all marine mammal 
hearing groups have been recently updated (NMFS 2024) as reflected 
below in table 3.

[[Page 13469]]



           Table 3--Marine Mammal Hearing Groups (NMFS, 2024)
------------------------------------------------------------------------
            Hearing group                 Generalized hearing range *
------------------------------------------------------------------------
Low-frequency (LF) cetaceans (baleen   7 Hz to 36 kHz.
 whales).
High-frequency (HF) cetaceans          150 Hz to 160 kHz.
 (dolphins, toothed whales, beaked
 whales, bottlenose whales).
Very High-frequency (VHF) cetaceans    200 Hz to 165 kHz.
 (true porpoises, Kogia, river
 dolphins, Cephalorhynchid,
 Lagenorhynchus cruciger & L.
 australis).
Phocid pinnipeds (PW) (underwater)     40 Hz to 90 kHz.
 (true seals).
Otariid pinnipeds (OW) (underwater)    60 Hz to 68 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 may not be as broad. Generalized hearing range
  chosen based on ~65 dB threshold from composite audiogram, previous
  analysis in NMFS 2018, and/or data from Southall et al. 2007; Southall
  et al. 2019. Additionally, animals are able to detect very loud sounds
  above and below that ``generalized'' hearing range.

    For more detail concerning these groups and associated frequency 
ranges, please see NMFS (2024) for a review of available information.

Potential Effects of Specified Activities on Marine Mammals and Their 
Habitat

    This section provides a discussion of the ways in which components 
of the specified activity may impact marine mammals and their habitat. 
The Estimated Take of Marine Mammals section later in this document 
includes a quantitative analysis of the number of individuals that are 
expected to be taken by this activity. The Negligible Impact Analysis 
and Determination section considers the content of this section, the 
Estimated Take of Marine Mammals section, and the Proposed Mitigation 
section, to draw conclusions regarding the likely impacts of these 
activities on the reproductive success or survivorship of individuals 
and whether those impacts are reasonably expected to, or reasonably 
likely to, adversely affect the species or stock through effects on 
annual rates of recruitment or survival.

Description of Sound Sources

    The marine soundscape is comprised of both ambient and 
anthropogenic sounds. Ambient sound is defined as the all-encompassing 
sound in a given place and is usually a composite of sound from many 
sources both near and far (ANSI 1995). The sound level of an area is 
defined by the total acoustical energy being generated by known and 
unknown sources. These sources may include physical (e.g., waves, wind, 
precipitation, earthquakes, ice, atmospheric sound), biological (e.g., 
sounds produced by marine mammals, fish, and invertebrates), and 
anthropogenic sound (e.g., vessels, dredging, aircraft, construction).
    The sum of the various natural and anthropogenic sound sources at 
any given location and time--which comprise ``ambient'' or 
``background'' sound--depends not only on the source levels (as 
determined by current weather conditions and levels of biological and 
shipping activity) but also on the ability of sound to propagate 
through the environment. In turn, sound propagation is dependent on the 
spatially and temporally varying properties of the water column and sea 
floor, and is frequency-dependent. As a result of the dependence on a 
large number of varying factors, ambient sound levels can be expected 
to vary widely over both coarse and fine spatial and temporal scales. 
Sound levels at a given frequency and location can vary by 10-20 
decibels (dB) from day to day (Richardson et al., 1995). The result is 
that, depending on the source type and its intensity, sound from the 
specified activities may be a negligible addition to the local 
environment or could form a distinctive signal that may affect marine 
mammals.
    In-water construction activities associated with the proposed 
project would include impact pile driving, vibratory pile driving and 
removal, tension anchoring, and rock socketing. The sounds produced by 
these activities fall into one of two general sound types: impulsive 
and non-impulsive. Impulsive sounds (e.g., explosions, gunshots, sonic 
booms, impact pile driving) are typically transient, brief (less than 1 
second), broadband, and consist of high peak sound pressure with rapid 
rise time and rapid decay (American National Standards Institute 
(ANSI), 1986; National Institute for Occupational Safety and Health 
(NIOSH), 1998; ANSI, 2005; NMFS, 2018). Non-impulsive sounds (e.g., 
aircraft, machinery operations such as drilling or dredging, vibratory 
pile driving, and active sonar systems) can be broadband, narrowband or 
tonal, brief or prolonged (continuous or intermittent), and typically 
do not have the high peak sound pressure with rapid rise/decay time 
that impulsive sounds do (ANSI, 1995; NIOSH, 1998; NMFS, 2018). The 
distinction between these two sound types is important because they 
have differing potential to cause physical effects, particularly with 
regard to hearing (e.g., Ward 1997 in Southall et al., 2007).
    Impact hammers operate by repeatedly dropping a heavy piston onto a 
pile to drive the pile into the substrate. Sound generated by impact 
hammers is characterized by rapid rise times and high peak levels, a 
potentially injurious combination (Hastings and Popper, 2005). 
Vibratory hammers install piles by vibrating them and allowing the 
weight of the hammer to push them into the sediment. Vibratory hammers 
produce significantly less sound than impact hammers. Peak sound 
pressure levels (SPLs) may be 180 dB or greater, but are generally 10 
to 20 dB lower than SPLs generated during impact pile driving of the 
same-sized pile (Oestman et al., 2009). Rise time is slower, reducing 
the probability and severity of injury, and sound energy is distributed 
over a greater amount of time (Nedwell and Edwards, 2002; Carlson et 
al., 2005).
    Rock socket or tension anchoring would be conducted using a DTH 
hammer. A DTH hammer is essentially a drill bit that drills through the 
bedrock using a rotating function like a normal drill, in concert with 
a hammering mechanism operated by a pneumatic (or sometimes hydraulic) 
component integrated into the DTH hammer to increase speed of progress 
through the substrate (i.e., it is similar to a ``hammer drill'' hand 
tool). Rock anchoring or socketing involves using DTH equipment to 
create a hole in the bedrock inside which the pile is placed to give it 
lateral and longitudinal strength. Tension anchoring involves creating 
a smaller hole below the bottom of a pile. A length of rebar is 
typically inserted in the small hole and is long enough to run up 
through the middle of a hollow pile to reach the surface where it is 
connected to the pile to provide additional mechanical support and 
stability to the pile. The sounds produced by DTH systems contain both 
a continuous, non-impulsive component

[[Page 13470]]

from the drilling action and an impulsive component from the hammering 
effect. Therefore, NMFS treats DTH systems as both impulsive (for 
estimating Level A harassment zones) and non-impulsive (for estimating 
Level B harassment zones) sound source types simultaneously.
    The likely or possible impacts of the ADOT&PFs proposed activity on 
marine mammals could involve both non-acoustic and acoustic stressors. 
Potential non-acoustic stressors could result from the physical 
presence of the equipment and personnel; however, any impacts to marine 
mammals are expected to primarily be acoustic in nature.

Acoustic Impacts

    The introduction of anthropogenic noise into the aquatic 
environment from pile driving is the primary means by which marine 
mammals may be harassed from the proposed activity. In general, animals 
exposed to natural or anthropogenic sound may experience physical and 
psychological effects, ranging in magnitude from none to severe 
(Southall et al., 2007). In general, exposure to pile driving and 
tension anchoring noise has the potential to result in an auditory 
threshold shift (TS) and behavioral reactions (e.g., avoidance, 
temporary cessation of foraging and vocalizing, changes in dive 
behavior). Exposure to anthropogenic noise can also lead to non-
observable physiological responses, such as an increase in stress 
hormones. Additional noise in a marine mammal's habitat can mask 
acoustic cues used by marine mammals to carry out daily functions such 
as communication and predator and prey detection. The effects of pile 
driving noise on marine mammals are dependent on several factors, 
including, but not limited to, sound type (e.g., impulsive vs. non-
impulsive), the species, age and sex class (e.g., adult male vs. mom 
with calf), duration of exposure, the distance between the pile and the 
animal, received levels, behavior at time of exposure, and previous 
history with exposure (Wartzok et al., 2004; Southall et al., 2007). 
Here we discuss physical auditory effects (TSs) followed by behavioral 
effects and potential impacts on habitat.
    NMFS defines a noise-induced TS as a change, usually an increase, 
in the threshold of audibility at a specified frequency or portion of 
an individual's hearing range above a previously established reference 
level (NMFS, 2018, 2024). The amount of TS is customarily expressed in 
dB. A TS can be permanent or temporary. As described in NMFS (2018, 
2024), there are numerous factors to consider when examining the 
consequence of TS, including, but not limited to, the signal temporal 
pattern (e.g., impulsive or non-impulsive), likelihood an individual 
would be exposed for a long enough duration or to a high enough level 
to induce a TS, the magnitude of the TS, time to recovery (seconds to 
minutes or hours to days), the frequency range of the exposure (i.e., 
spectral content), the hearing frequency range of the exposed species 
relative to the signal's frequency spectrum (i.e., how an animal uses 
sound within the frequency band of the signal; e.g., Kastelein et al., 
2014), and the overlap between the animal and the source (e.g., 
spatial, temporal, and spectral).
    Auditory Injury--NMFS defines auditory injury as ``damage to the 
inner ear that can result in destruction of tissue . . . which may or 
may not result in permanent threshold shift'' (PTS; NMFS, 2024). NMFS 
defines PTS as a permanent, irreversible increase in the threshold of 
audibility at a specified frequency or portion of an individual's 
hearing range above a previously established reference level (NMFS, 
2024). PTS does not generally affect more than a limited frequency 
range, and an animal that has incurred PTS has incurred some level of 
hearing loss at the relevant frequencies; typically, animals with PTS 
are not functionally deaf (Au and Hastings, 2008; Finneran, 2016). 
Available data from humans and other terrestrial mammals indicate that 
a 40-dB TS approximates PTS onset (see Ward et al., 1958, 1959, 1960; 
Kryter et al., 1966; Miller, 1974; Ahroon et al., 1996; Henderson et 
al., 2008). PTS levels for marine mammals are estimates, as with the 
exception of a single study unintentionally inducing PTS in a harbor 
seal (Kastak et al., 2008), there are no empirical data measuring PTS 
in marine mammals largely due to the fact that, for various ethical 
reasons, experiments involving anthropogenic noise exposure at levels 
inducing PTS are not typically pursued or authorized (NMFS, 2018).
    Temporary Threshold Shift (TTS)--TTS is a temporary, reversible 
increase in the threshold of audibility at a specified frequency or 
portion of an individual's hearing range above a previously established 
reference level (NMFS, 2018). Based on data from cetacean TTS 
measurements (Southall et al., 2007, 2019), a TTS of 6 dB is considered 
the minimum TS clearly larger than any day-to-day or session-to-session 
variation in a subject's normal hearing ability (Schlundt et al., 2000; 
Finneran et al., 2000, 2002). As described in Finneran (2015), marine 
mammal studies have shown the amount of TTS increases with cumulative 
sound exposure level (SELcum) in an accelerating fashion: At 
low exposures with lower SELcum, the amount of TTS is 
typically small and the growth curves have shallow slopes. At exposures 
with higher SELcum, the growth curves become steeper and 
approach linear relationships with the noise SEL.
    Depending on the degree (elevation of threshold in dB), duration 
(i.e., recovery time), and frequency range of TTS, and the context in 
which it is experienced, TTS can have effects on marine mammals ranging 
from discountable to serious (similar to those discussed in auditory 
masking, below). For example, a marine mammal may be able to readily 
compensate for a brief, relatively small amount of TTS in a non-
critical frequency range that takes place during a time when the animal 
is traveling through the open ocean, where ambient noise is lower and 
there are not as many competing sounds present. Alternatively, a larger 
amount and longer duration of TTS sustained during a time when 
communication is critical for successful mother/calf interactions could 
have more serious impacts. We note that reduced hearing sensitivity as 
a simple function of aging has been observed in marine mammals, as well 
as humans and other taxa (Southall et al., 2007), so we can infer that 
strategies exist for coping with this condition to some degree, though 
likely not without cost.
    Many studies have examined noise-induced hearing loss in marine 
mammals (see Finneran (2015) and Southall et al. (2019) for summaries). 
TTS is the mildest form of hearing impairment that can occur during 
exposure to sound (Kryter, 2013). While experiencing TTS, the hearing 
threshold rises, and a sound must be at a higher level in order to be 
heard. In terrestrial and marine mammals, TTS can last from minutes or 
hours to days (in cases of strong TTS). In many cases, hearing 
sensitivity recovers rapidly after exposure to the sound ends. For 
pinnipeds in water, measurements of TTS are limited to harbor seals, 
elephant seals (Mirounga angustirostris), bearded seals (Erignathus 
barbatus) and California sea lions (Kastak et al., 1999, 2007; 
Kastelein et al., 2019b, 2019c, 2021, 2022a, 2022b; Reichmuth et al., 
2019; Sills et al., 2020). These studies examined hearing thresholds 
measured in marine mammals before and after exposure to intense or 
long-duration sound exposures. The difference between the pre-exposure 
and post-

[[Page 13471]]

exposure thresholds can be used to determine the amount of TS at 
various post-exposure times.
    The amount and onset of TTS depends on the exposure frequency. 
Sounds at low frequencies, well below the region of best sensitivity 
for a species or hearing group, are less hazardous than those at higher 
frequencies, near the region of best sensitivity (Finneran and 
Schlundt, 2013). At low frequencies, onset-TTS exposure levels are 
higher compared to those in the region of best sensitivity (i.e., a low 
frequency noise would need to be louder to cause TTS onset when TTS 
exposure level is higher), as shown for harbor porpoises and harbor 
seals (Kastelein et al., 2019a, 2019c). Note that in general, harbor 
seals have a lower TTS onset than other measured pinniped species 
(Finneran, 2015). In addition, TTS can accumulate across multiple 
exposures, but the resulting TTS will be less than the TTS from a 
single, continuous exposure with the same SEL (Mooney et al., 2009; 
Finneran et al., 2010; Kastelein et al., 2014, 2015). This means that 
TTS predictions based on the total, SELcum will overestimate 
the amount of TTS from intermittent exposures, such as sonars and 
impulsive sources. Nachtigall et al. (2018) describes measurements of 
hearing sensitivity of multiple odontocete species (i.e., bottlenose 
dolphin, harbor porpoise, beluga (Delphinapterus leucas), and false 
killer whale (Pseudorca crassidens)) when a relatively loud sound was 
preceded by a warning sound. These captive animals were shown to reduce 
hearing sensitivity when warned of an impending intense sound. Based on 
these experimental observations of captive animals, the authors suggest 
that wild animals may dampen their hearing during prolonged exposures 
or if conditioned to anticipate intense sounds. Another study showed 
that echolocating animals (including odontocetes) might have anatomical 
specializations that might allow for conditioned hearing reduction and 
filtering of low-frequency ambient noise, including increased stiffness 
and control of middle ear structures and placement of inner ear 
structures (Ketten et al., 2021). Additionally, the existing marine 
mammal TTS data come from a limited number of individuals within these 
species.
    Relationships between TTS and PTS thresholds have not been studied 
in marine mammals, but such relationships are assumed to be similar to 
those in humans and other terrestrial mammals. PTS typically occurs at 
exposure levels at least several dBs above that inducing mild TTS 
(e.g., a 40-dB TS approximates PTS onset (Kryter et al., 1966; Miller, 
1974), while a 6-dB TS approximates TTS onset (Southall et al., 2007, 
2019). Based on data from terrestrial mammals, a precautionary 
assumption is that the PTS thresholds for impulsive sounds (such as 
impact pile driving pulses as received close to the source) are at 
least 6 dB higher than the TTS threshold on a peak-pressure basis and 
PTS SELcum thresholds are 15 to 20 dB higher than TTS 
SELcum thresholds (Southall et al., 2007, 2019). Given the 
higher level of sound or longer exposure duration necessary to cause 
PTS as compared with TTS, it is considerably less likely that PTS could 
occur.
    Pile installation at the Angoon Ferry Terminal Modifications 
Project would require a combination DTH, impact, and vibratory pile 
driving and removal. Construction at the project site would only 
include one method of pile installation or removal at a time. Proposed 
construction activities are not expected to be constant and pauses in 
the activities producing sound are likely to occur each day. Given 
these pauses and that many marine mammals are likely moving through the 
project areas and not remaining for extended periods of time, the 
potential for TS declines.
    Behavioral Harassment-- Exposure to noise from pile driving and 
removal and tension anchoring also has the potential to behaviorally 
disturb marine mammals. Available studies show wide variation in 
response to underwater sound; therefore, it is difficult to predict 
specifically how any given sound in a particular instance might affect 
marine mammals perceiving the signal. If a marine mammal does react 
briefly to an underwater sound by changing its behavior or moving a 
small distance, the impacts of the change are unlikely to be 
significant to the individual, let alone the stock or population. 
However, if a sound source displaces marine mammals from an important 
feeding or breeding area for a prolonged period, impacts on individuals 
and populations could be significant (e.g., Lusseau and Bejder, 2007; 
Weilgart, 2007; National Research Council (NRC), 2005).
    Disturbance may result in changing durations of surfacing and 
dives, number of blows per surfacing, or moving direction and/or speed; 
reduced/increased vocal activities; changing/cessation of certain 
behavioral activities (such as socializing or feeding); visible startle 
response or aggressive behavior (such as tail/fluke slapping or jaw 
clapping); or avoidance of areas where sound sources are located. 
Pinnipeds may increase their haulout time, possibly to avoid in-water 
disturbance (Thorson and Reyff, 2006). Behavioral responses to sound 
are highly variable and context-specific and any reactions depend on 
numerous intrinsic and extrinsic factors (e.g., species, state of 
maturity, experience, current activity, reproductive state, auditory 
sensitivity, time of day), as well as the interplay between factors 
(e.g., Richardson et al., 1995; Wartzok et al., 2003; Southall et al., 
2007; Weilgart, 2007; Archer et al., 2010). Behavioral reactions can 
vary not only among individuals but also within an individual, 
depending on previous experience with a sound source, context, and 
numerous other factors (Ellison et al., 2012), and can vary depending 
on characteristics associated with the sound source (e.g., whether it 
is moving or stationary, number of sources, distance from the source). 
In general, pinnipeds seem more tolerant of, or at least habituate more 
quickly to, potentially disturbing underwater sound than do cetaceans, 
and generally seem to be less responsive to exposure to industrial 
sound than most cetaceans. Please see appendices B and C of Southall et 
al. (2007) and Gomez et al. (2016) for a review of studies involving 
marine mammal behavioral responses to sound.
    Habituation can occur when an animal's response to a stimulus wanes 
with repeated exposure, usually in the absence of unpleasant associated 
events (Wartzok et al., 2004). Animals are most likely to habituate to 
sounds that are predictable and unvarying. It is important to note that 
habituation is appropriately considered as a ``progressive reduction in 
response to stimuli that are perceived as neither aversive nor 
beneficial,'' rather than as, more generally, moderation in response to 
human disturbance (Bejder et al., 2009). The opposite process is 
sensitization, when an unpleasant experience leads to subsequent 
responses, often in the form of avoidance, at a lower level of 
exposure.
    As noted above, behavioral state may affect the type of response. 
For example, animals that are resting may show greater behavioral 
change in response to disturbing sound levels than animals that are 
highly motivated to remain in an area for feeding (Richardson et al., 
1995; Wartzok et al., 2004; National Research Council (NRC), 2005). 
Controlled experiments with captive marine mammals have showed 
pronounced behavioral reactions, including avoidance of loud sound 
sources (Ridgway et al., 1997; Finneran et al., 2003). Observed 
responses of wild marine mammals to loud pulsed sound

[[Page 13472]]

sources (e.g., seismic airguns) have been varied but often consist of 
avoidance behavior or other behavioral changes (Richardson et al., 
1995; Morton and Symonds, 2002; Nowacek et al., 2007).
    Available studies show wide variation in response to underwater 
sound; therefore, it is difficult to predict specifically how any given 
sound in a particular instance might affect marine mammals perceiving 
the signal (e.g., Erbe et al., 2019). If a marine mammal does react 
briefly to an underwater sound by changing its behavior or moving a 
small distance, the impacts of the change are unlikely to be 
significant to the individual, let alone the stock or population. 
However, if a sound source displaces marine mammals from an important 
feeding or breeding area for a prolonged period, impacts on individuals 
and populations could be significant (e.g., Lusseau and Bejder, 2007; 
Weilgart, 2007; NRC, 2005). However, there are broad categories of 
potential response, which we describe in greater detail here, that 
include alteration of dive behavior, alteration of foraging behavior, 
effects to breathing, interference with or alteration of vocalization, 
avoidance, and flight.
    Changes in dive behavior can vary widely and may consist of 
increased or decreased dive times and surface intervals as well as 
changes in the rates of ascent and descent during a dive (e.g., Frankel 
and Clark, 2000; Costa et al., 2003; Ng and Leung, 2003; Nowacek et 
al., 2004; Goldbogen et al., 2013a, 2013b, Blair et al., 2016). 
Variations in dive behavior may reflect interruptions in biologically 
significant activities (e.g., foraging) or they may be of little 
biological significance. The impact of an alteration to dive behavior 
resulting from an acoustic exposure depends on what the animal is doing 
at the time of the exposure and the type and magnitude of the response.
    Disruption of feeding behavior can be difficult to correlate with 
anthropogenic sound exposure, so it is usually inferred by observed 
displacement from known foraging areas, the appearance of secondary 
indicators (e.g., bubble nets or sediment plumes), or changes in dive 
behavior. In response to playbacks of vibratory pile driving sounds, 
captive bottlenose dolphins showed changes in target detection and 
number of clicks used for a trained echolocation task (Branstetter et 
al. 2018). Similarly, harbor porpoises trained to collect fish during 
playback of impact pile driving sounds also showed potential changes in 
behavior and task success, though individual differences were prevalent 
(Kastelein et al. 2019d). As for other types of behavioral response, 
the frequency, duration, and temporal pattern of signal presentation, 
as well as differences in species sensitivity, are likely contributing 
factors to differences in response in any given circumstance (e.g., 
Croll et al., 2001; Nowacek et al., 2004; Madsen et al., 2006; Yazvenko 
et al., 2007). A determination of whether foraging disruptions incur 
fitness consequences would require information on or estimates of the 
energetic requirements of the affected individuals and the relationship 
between prey availability, foraging effort and success, and the life 
history stage of the animal.
    A flight response is a dramatic change in normal movement to a 
directed and rapid movement away from the perceived location of a sound 
source. The flight response differs from other avoidance responses in 
the intensity of the response (e.g., directed movement, rate of 
travel). Relatively little information on flight responses of marine 
mammals to anthropogenic signals exist, although observations of flight 
responses to the presence of predators have occurred (Connor and 
Heithaus, 1996; Bowers et al., 2018). The result of a flight response 
could range from brief, temporary exertion and displacement from the 
area where the signal provokes flight to, in extreme cases, marine 
mammal strandings (England et al., 2001). However, it should be noted 
that response to a perceived predator does not necessarily invoke 
flight (Ford and Reeves, 2008), and whether individuals are solitary or 
in groups may influence the response.
    Behavioral disturbance can also impact marine mammals in more 
subtle ways. Increased vigilance may result in costs related to 
diversion of focus and attention (i.e., when a response consists of 
increased vigilance, it may come at the cost of decreased attention to 
other critical behaviors such as foraging or resting). These effects 
have generally not been demonstrated for marine mammals, but studies 
involving fishes and terrestrial animals have shown that increased 
vigilance may substantially reduce feeding rates (e.g., Beauchamp and 
Livoreil, 1997; Fritz et al., 2002; Purser and Radford, 2011). In 
addition, chronic disturbance can cause population declines through 
reduction of fitness (e.g., decline in body condition) and subsequent 
reduction in reproductive success, survival, or both (e.g., Harrington 
and Veitch, 1992; Daan et al., 1996; Bradshaw et al., 1998). However, 
Ridgway et al. (2006) reported that increased vigilance in bottlenose 
dolphins exposed to sound over a 5-day period did not cause any sleep 
deprivation or stress effects.
    Stress Responses--An animal's perception of a threat may be 
sufficient to trigger stress responses consisting of some combination 
of behavioral responses, autonomic nervous system responses, 
neuroendocrine responses, or immune responses (e.g., Seyle, 1950; 
Moberg, 2000). In many cases, an animal's first and sometimes most 
economical (in terms of energetic costs) response is behavioral 
avoidance of the potential stressor. Autonomic nervous system responses 
to stress typically involve changes in heart rate, blood pressure, and 
gastrointestinal activity. These responses have a relatively short 
duration and may or may not have a significant long-term effect on an 
animal's fitness.
    Neuroendocrine stress responses often involve the hypothalamus-
pituitary-adrenal system. Virtually all neuroendocrine functions that 
are affected by stress--including immune competence, reproduction, 
metabolism, and behavior--are regulated by pituitary hormones. Stress-
induced changes in the secretion of pituitary hormones have been 
implicated in failed reproduction, altered metabolism, reduced immune 
competence, and behavioral disturbance (e.g., Moberg, 1987; Blecha, 
2000). Increases in the circulation of glucocorticoids are also equated 
with stress (Romano et al., 2004).
    The primary distinction between stress (which is adaptive and does 
not normally place an animal at risk) and ``distress'' is the cost of 
the response. During a stress response, an animal uses glycogen stores 
that can be quickly replenished once the stress is alleviated. In such 
circumstances, the cost of the stress response would not pose serious 
fitness consequences. However, when an animal does not have sufficient 
energy reserves to satisfy the energetic costs of a stress response, 
energy resources must be diverted from other functions. This state of 
distress will last until the animal replenishes its energetic reserves 
sufficient to restore normal function.
    Relationships between these physiological mechanisms, animal 
behavior, and the costs of stress responses are well studied through 
controlled experiments and for both laboratory and free-ranging animals 
(e.g., Holberton et al., 1996; Hood et al., 1998; Jessop et al., 2003; 
Krausman et al., 2004; Lankford et al., 2005). Stress responses due to 
exposure to anthropogenic sounds or other stressors and their effects 
on marine mammals have also been reviewed (Fair and Becker, 2000; 
Romano et al., 2002a) and, more rarely, studied in wild populations 
(e.g., Romano et al., 2002b). For

[[Page 13473]]

example, Rolland et al. (2012) found that noise reduction from reduced 
ship traffic in the Bay of Fundy was associated with decreased stress 
in North Atlantic right whales. These and other studies lead to a 
reasonable expectation that some marine mammals will experience 
physiological stress responses upon exposure to acoustic stressors and 
that it is possible that some of these would be classified as 
``distress.'' In addition, any animal experiencing TTS would likely 
also experience stress responses (NRC, 2003), however distress is an 
unlikely result of this project based on observations of marine mammals 
during previous, similar projects in the area.
    Masking--Sound can disrupt behavior through masking, or interfering 
with, an animal's ability to detect, recognize, or discriminate between 
acoustic signals of interest (e.g., those used for intraspecific 
communication and social interactions, prey detection, predator 
avoidance, navigation) (Richardson et al., 1995). Masking occurs when 
the receipt of a sound is interfered with by another coincident sound 
at similar frequencies and at similar or higher intensity, and may 
occur whether the sound is natural (e.g., snapping shrimp, wind, waves, 
precipitation) or anthropogenic (e.g., pile driving, shipping, sonar, 
seismic exploration) in origin. The ability of a noise source to mask 
biologically important sounds depends on the characteristics of both 
the noise source and the signal of interest (e.g., signal-to-noise 
ratio, temporal variability, direction), in relation to each other and 
to an animal's hearing abilities (e.g., sensitivity, frequency range, 
critical ratios, frequency discrimination, directional discrimination, 
age or TTS hearing loss), and existing ambient noise and propagation 
conditions. Masking of natural sounds can result when human activities 
produce high levels of background sound at frequencies important to 
marine mammals. Conversely, if the background level of underwater sound 
is high (e.g., on a day with strong wind and high waves), an 
anthropogenic sound source would not be detectable as far away as would 
be possible under quieter conditions and would itself be masked.
    Airborne Acoustic Effects--Pinnipeds that occur near the project 
site could be exposed to airborne sounds associated with pile driving 
or DTH that have the potential to cause behavioral harassment, 
depending on their distance from the activities. Cetaceans are not 
expected to be exposed to airborne sounds that would result in 
harassment as defined under the MMPA.
    Airborne noise would primarily be an issue for pinnipeds that are 
swimming or hauled out near the project site within the range of noise 
levels elevated above the airborne acoustic harassment criteria. We 
recognize that pinnipeds in the water could be exposed to airborne 
sound that may result in behavioral harassment when swimming with their 
heads above water. Most likely, airborne sound would cause behavioral 
responses similar to those discussed above in relation to underwater 
sound. For instance, anthropogenic sound could cause hauled-out 
pinnipeds to exhibit changes in their normal behavior, such as 
reduction in vocalizations, or cause them to temporarily abandon the 
area and move further from the source. However, these animals would 
previously have been `taken' because of exposure to underwater sound 
above the behavioral harassment thresholds, which are in all cases 
larger than those associated with airborne sound. Thus, the behavioral 
harassment of these animals is already accounted for in these estimates 
of potential take. Therefore, we do not believe that authorization of 
incidental take resulting from airborne sound for pinnipeds is 
warranted, and airborne sound is not discussed further.

Marine Mammal Habitat Effects

    ADOT&PF's proposed construction activities could have localized, 
temporary impacts on marine mammal habitat, including prey, by 
increasing in-water SPLs and slightly decreasing water quality. 
Increased noise levels may affect acoustic habitat (see Masking) and 
adversely affect marine mammal prey in the vicinity of the project area 
(see discussion below). During DTH, impact, and vibratory pile driving, 
elevated levels of underwater noise would ensonify project areas where 
both fish and mammals occur and could affect foraging success. 
Additionally, marine mammals may avoid the area during construction; 
however, displacement due to noise is expected to be temporary and is 
not expected to result in long-term effects to the individuals or 
populations.
    Water Quality--In-water pile driving activities would also cause 
short-term effects on water quality due to increased turbidity. 
Temporary and localized increase in turbidity near the seafloor would 
occur in the immediate area surrounding where piles are installed or 
removed due benthic sediment disturbance. In general, turbidity 
associated with pile installation is localized to about a 25 ft (7.6 m) 
radius around the pile (Everitt et al., 1980). The suspended solids 
from disturbed sediment at project site would settle out of the water 
column within a few hours. Studies of the effects of turbid water on 
fish (marine mammal prey) suggest that concentrations of suspended 
sediment can reach thousands of milligrams per liter before an acute 
toxic reaction is expected (Burton, 1993).
    Effects from turbidity and sedimentation are expected to be short-
term, minor, and localized. Suspended solids in the water column should 
dissipate and quickly return to background levels in all construction 
scenarios. Turbidity within the water column has the potential to 
reduce the level of oxygen in the water and irritate the gills of prey 
fish species in the proposed project area. However, suspended sediment 
associated with the project would be temporary and localized, and fish 
in the proposed project area would be able to move away from and avoid 
the areas where plumes may occur. Therefore, it is expected that the 
impacts on prey fish species from turbidity, and therefore on marine 
mammals, would be minimal and temporary. In general, the area likely 
impacted by the proposed construction activities is relatively small 
compared to the total available marine mammal habitat. Therefore, we 
expect the impact from increased turbidity levels to be discountable to 
marine mammals and do not discuss it further.
    In-water Effects on Potential Foraging Habitat--The proposed 
activities would not result in permanent impacts to habitats used 
directly by marine mammals outside of the actual footprint of the 
constructed dock. The total seafloor area affected by pile installation 
and removal is a very small area compared to the vast foraging area 
available to marine mammals in Chatham Strait and other inland waters 
of Southeast Alaska. Pile extraction and installation, tension 
anchoring, and rock socketing may have impacts on benthic invertebrate 
species primarily associated with disturbance of sediments that may 
cover or displace some invertebrates. The impacts would be temporary 
and highly localized, and no habitat would be permanently displaced by 
construction. Therefore, it is expected that impacts on foraging 
opportunities for marine mammals due to construction of the dock would 
be minimal.
    It is possible that avoidance by potential prey (i.e., fish) in the 
immediate area may occur due to temporary loss of this foraging 
habitat. The duration of fish avoidance of this area after pile driving 
stops is unknown, but we anticipate a rapid return to normal 
recruitment, distribution and

[[Page 13474]]

behavior. Any behavioral avoidance by fish of the disturbed area would 
still leave large areas of fish and marine mammal foraging habitat in 
the nearby vicinity in the in the project area and surrounding waters.
    Effects on Potential Prey--Construction activities would produce 
continuous, non-impulsive (i.e., vibratory pile driving, tension 
anchoring, and rock socketing) and intermittent impulsive (i.e., impact 
pile driving, tension anchoring, and rock socketing) sounds. Sound may 
affect marine mammals through impacts on the abundance, behavior, or 
distribution of prey species (e.g., fish). Marine mammal prey varies by 
species, season, and location. Here, we describe studies regarding the 
effects of noise on known marine mammal prey.
    Fish utilize the soundscape and components of sound in their 
environment to perform important functions such as foraging, predator 
avoidance, mating, and spawning (Zelick et al., 1999; Fay, 2009). 
Depending on their hearing anatomy and peripheral sensory structures, 
which vary among species, fishes hear sounds using pressure and 
particle motion sensitivity capabilities and detect the motion of 
surrounding water (Fay et al., 2008). The potential effects of noise on 
fishes depends on the overlapping frequency range, distance from the 
sound source, water depth of exposure, and species-specific hearing 
sensitivity, anatomy, and physiology. Key impacts to fishes may include 
behavioral responses, hearing damage, barotrauma (pressure-related 
injuries), and mortality.
    Fish react to sounds which are especially strong and/or 
intermittent low-frequency sounds, and behavioral responses such as 
flight or avoidance are the most likely effects. Short duration, sharp 
sounds can cause overt or subtle changes in fish behavior and local 
distribution. The reaction of fish to noise depends on the 
physiological state of the fish, past exposures, motivation (e.g., 
feeding, spawning, migration), and other environmental factors. 
Hastings and Popper (2005a) identified several studies that suggest 
fish may relocate to avoid certain areas of sound energy. Additional 
studies have documented effects of pile driving on fish, several of 
which are based on studies in support of large, multiyear bridge 
construction projects (e.g., Scholik and Yan, 2001; Popper and 
Hastings, 2009). Many studies have demonstrated that impulse sounds 
might affect the distribution and behavior of some fishes, potentially 
impacting foraging opportunities or increasing energetic costs (e.g., 
Pearson et al., 1992; Skalski et al., 1992; Santulli et al., 1999; 
Fewtrell and McCauley, 2012; Paxton et al., 2017). In response to pile 
driving, Pacific sardines (Sardinops sagax) and northern anchovies 
(Engraulis mordax) may exhibit an immediate startle response to 
individual strikes but return to ``normal'' pre-strike behavior 
following the conclusion of pile driving with no evidence of injury as 
a result (see NAVFAC, 2014). However, some studies have shown no or 
slight reaction to impulse sounds (e.g., Wardle et al., 2001; Popper et 
al., 2005; Jorgenson and Gyselman, 2009; Pe[ntilde]a et al., 2013).
    SPLs of sufficient strength have been known to cause injury to fish 
and fish mortality (summarized in Popper et al. 2014). However, in most 
fish species, hair cells in the ear continuously regenerate and loss of 
auditory function likely is restored when damaged cells are replaced 
with new cells. Halvorsen et al. (2012b) showed that a TTS of 4-6 dB 
was recoverable within 24 hours for one species. Impacts would be most 
severe when the individual fish is close to the source and when the 
duration of exposure is long. Injury caused by barotrauma can range 
from slight to severe and can cause death, and is most likely for fish 
with swim bladders. Barotrauma injuries have been documented during 
controlled exposure to impact pile driving (Halvorsen et al., 2012a; 
Casper et al., 2013) and the greatest potential effect on fish during 
the proposed project would occur during impact pile driving. Vibratory 
pile driving may elicit behavioral reactions from fish such as 
temporary avoidance of the area but is unlikely to cause injuries to 
fish or have persistent effects on local fish populations. In addition, 
it should be noted that the area in question is low-quality habitat 
since it is already developed and experiences anthropogenic noise from 
vessel traffic.
    The most likely impact to fishes from pile driving and DTH 
activities in the project area would be temporary behavioral avoidance 
of the area. The duration of fish avoidance of the area after pile 
driving stops is unknown but a rapid return to normal recruitment, 
distribution, and behavior is anticipated. There are times of known 
seasonal marine mammal foraging when fish are aggregating but the 
impacted areas are small portions of the total foraging habitats 
available in the regions. In general, impacts to marine mammal prey 
species are expected to be minor and temporary. Further, it is 
anticipated that preparation activities for pile driving and DTH 
activities (i.e., positioning of the hammer) and upon initial startup 
of devices would cause fish to move away from the affected area where 
injuries may occur. Therefore, relatively small portions of the 
proposed project area would be affected for short periods of time, and 
the potential for effects on fish to occur would be temporary and 
limited to the duration of sound[hyphen]generating activities.
    Construction activities, in the form of increased turbidity, also 
have the potential to adversely affect forage fish in the project area. 
Pacific herring (Clupea pallasii) is a primary prey species of Steller 
sea lions, humpback whales, and many other marine mammal species that 
occur in the project areas. As discussed earlier, increased turbidity 
is expected to occur in the immediate vicinity (approximately 25 ft 
(7.6 m) or less) of construction activities (Everitt et al., 1980). 
However, suspended solids are expected to dissipate quickly within a 
single tidal cycle. Given the limited area affected and high tidal 
dilution rates any effects on forage fish are expected to be minor or 
negligible. In addition, best management practices would be in effect 
to limit the extent of turbidity to the immediate project area.
    In summary, given the short daily duration of sound associated with 
pile driving and DTH activities, and the relatively small areas being 
affected, pile driving and DTH activities associated with the proposed 
action are not likely to have a permanent adverse effect on any fish 
habitat, or populations of fish species. Thus, we conclude that impacts 
of the specified activity are not likely to have more than short-term 
adverse effects on any prey habitat or populations of prey species. 
Further, any impacts to marine mammal habitat are not expected to 
result in significant or long-term consequences for individual marine 
mammals, or to contribute to adverse impacts on their populations.

Estimated Take of Marine Mammals

    This section provides an estimate of the number of incidental takes 
proposed for authorization through the IHA, which will inform NMFS' 
consideration of ``small numbers,'' the negligible impact 
determinations, and impacts on subsistence uses.
    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

[[Page 13475]]

marine mammal or marine mammal stock in the wild by causing disruption 
of behavioral patterns, including, but not limited to, migration, 
breathing, nursing, breeding, feeding, or sheltering (Level B 
harassment).
    Authorized takes would primarily be by Level B harassment, as use 
of the acoustic sources (i.e., pile driving, tension anchoring, and 
rock socketing) has 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 during 
rock socketing. The proposed mitigation and monitoring measures are 
expected to minimize the severity of the taking to the extent 
practicable.
    As described previously, no serious injury or mortality is 
anticipated or proposed to be authorized for this activity. Below we 
describe how the proposed take numbers are estimated.
    For acoustic impacts, generally speaking, we estimate take by 
considering: (1) acoustic criteria above which NMFS believes the best 
available science indicates marine mammals will likely be behaviorally 
harassed or incur some degree of auditory injury; (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) the number of days of activities. We note that while 
these factors can contribute to a basic calculation to provide an 
initial prediction of potential takes, additional information that can 
qualitatively inform take estimates is also sometimes available (e.g., 
previous monitoring results or average group size). Below, we describe 
the factors considered here in more detail and present the proposed 
take estimates.

Acoustic Criteria

    NMFS recommends the use of acoustic criteria 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 auditory injury of some degree (equated 
to Level A harassment). We note that the criteria for auditory injury, 
as well as the names of two hearing groups, have been recently updated 
(NMFS 2024) as reflected below in the Level A harassment section.
    Level B Harassment--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 or exposure context (e.g., frequency, predictability, duty 
cycle, duration of the exposure, signal-to-noise ratio, distance to the 
source), the environment (e.g., bathymetry, other noises in the area, 
predators in the area), and the receiving animals (hearing, motivation, 
experience, demography, life stage, depth) and can be difficult to 
predict (e.g., Southall et al., 2007, 2021, Ellison et al., 2012). 
Based on what the available science indicates and the practical need to 
use a threshold based on a metric that is both predictable and 
measurable for most activities, NMFS typically uses a generalized 
acoustic threshold based on received level to estimate the onset of 
behavioral harassment. NMFS generally predicts that marine mammals are 
likely to be behaviorally harassed in a manner considered to be Level B 
harassment when exposed to underwater anthropogenic noise above root-
mean-squared pressure received levels (RMS SPL) of 120 dB (referenced 
to 1 micropascal (re 1 [mu]Pa)) for continuous (e.g., vibratory pile 
driving, drilling) and above RMS SPL 160 dB re 1 [mu]Pa for non-
explosive impulsive (e.g., seismic airguns) or intermittent (e.g., 
scientific sonar) sources. Generally speaking, Level B harassment take 
estimates based on these behavioral harassment thresholds are expected 
to include any likely takes by TTS as, in most cases, the likelihood of 
TTS occurs at distances from the source less than those at which 
behavioral harassment is likely. TTS of a sufficient degree can 
manifest as behavioral harassment, as reduced hearing sensitivity and 
the potential reduced opportunities to detect important signals 
(conspecific communication, predators, prey) may result in changes in 
behavior patterns that would not otherwise occur.
    ADOT&PF's proposed activity includes the use of continuous 
(vibratory pile driving/removal and DTH) and impulsive (impact pile 
driving and DTH) sources, and therefore the RMS SPL thresholds of 120 
and 160 dB re 1 [mu]Pa are applicable.
    Level A harassment--NMFS' Updated Technical Guidance for Assessing 
the Effects of Anthropogenic Sound on Marine Mammal Hearing (Version 
3.0) (Updated Technical Guidance, 2024) identifies dual criteria to 
assess auditory injury (Level A harassment) to five different 
underwater 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&PF's proposed activity includes the 
use of impulsive (impact pile driving and DTH) and non-impulsive 
(vibratory pile driving/removal and DTH) sources.
    The 2024 Updated Technical Guidance criteria include both updated 
thresholds and updated weighting functions for each hearing group. The 
thresholds are provided in table 4. The references, analysis, and 
methodology used in the development of the criteria are described in 
NMFS' 2024 Updated Technical Guidance, which may be accessed at: 
https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance-other-acoustic-tools.

                          Table 4--Thresholds Identifying the Onset of Auditory Injury
----------------------------------------------------------------------------------------------------------------
                                               Auditory injury onset acoustic thresholds * (received level)
             Hearing group              ------------------------------------------------------------------------
                                                  Impulsive                         Non-impulsive
----------------------------------------------------------------------------------------------------------------
Low-Frequency (LF) Cetaceans...........  Cell 1: Lpk,flat: 222 dB;   Cell 2: LE,LF,24h: 197 dB.
                                          LE,LF,24h: 183 dB.
High-Frequency (HF) Cetaceans..........  Cell 3: Lpk,flat: 230 dB;   Cell 4: LE,HF,24h: 201 dB.
                                          LE,HF,24h: 193 dB.
Very High-Frequency (VHF) Cetaceans....  Cell 5: Lpk,flat: 202 dB;   Cell 6: LE,VHF,24h: 181 dB.
                                          LE,VHF,24h: 159 dB.
Phocid Pinnipeds (PW) (Underwater).....  Cell 7: Lpk,flat: 223 dB;   Cell 8: LE,PW,24h: 195 dB.
                                          LE,PW,24h: 183 dB.
Otariid Pinnipeds (OW) (Underwater)....  Cell 9: Lpk,flat: 230 dB;   Cell 10: LE,OW,24h: 199 dB.
                                          LE,OW,24h: 185 dB.
----------------------------------------------------------------------------------------------------------------
* Dual metric criteria for impulsive sounds: Use whichever criteria results in the larger isopleth for
  calculating auditory injury onset. If a non-impulsive sound has the potential of exceeding the peak sound
  pressure level criteria associated with impulsive sounds, the PK SPL criteria are recommended for
  consideration for non-impulsive sources.

[[Page 13476]]

 
Note: Peak sound pressure level (Lp,0-pk) has a reference value of 1 [micro]Pa, and weighted cumulative sound
  exposure level (LE,p) has a reference value of 1 [micro]Pa\2\s. In this table, criteria are abbreviated to be
  more reflective of International Organization for Standardization (ISO) standards (ISO 2017; ISO 2020). The
  subscript ``flat'' is being included to indicate peak sound pressure are flat weighted or unweighted within
  the generalized hearing range of marine mammals underwater (i.e., 7 Hz to 165 kHz). The subscript associated
  with cumulative sound exposure level criteria indicates the designated marine mammal auditory weighting
  function (LF, HF, and VHF cetaceans, and PW and OW pinnipeds) and that the recommended accumulation period is
  24 hours. The weighted cumulative sound exposure level criteria 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 criteria will be exceeded.

Ensonified Area

    Here, we describe operational and environmental parameters of the 
activity that are used in estimating the area ensonified above the 
acoustic thresholds, including source levels and transmission loss 
coefficient.
    The sound field in the proposed project areas is the existing 
background noise plus additional construction noise from the proposed 
project. Marine mammals are expected to be affected via sound generated 
by the primary components of the project activities (i.e., pile driving 
and removal, tension anchoring, and rock socketing).
    The Angoon Ferry Terminal Modifications Project includes vibratory 
pile installation and removal, impact pile driving, tension anchoring, 
and rock socketing. Source levels for these activities are based on 
reviews of measurements of the same or similar types and dimensions of 
piles available in the literature. Source levels for each piles size 
and activity for the Angoon Ferry Terminal Modifications Project are 
presented in table 5. Source levels for vibratory installation and 
removal of piles of the same diameter are assumed to be the same.

 Table 5--Estimates of Mean Underwater Sound Levels Generated During Vibratory Pile Driving and Removal, Impact
                               Pile Driving, Tension Anchoring, and Rock Socketing
----------------------------------------------------------------------------------------------------------------
                                                 Proxy sound source levels at
                                                     10m (dB re 1 [mu]Pa)
             Pile size and method             ---------------------------------             Reference
                                                RMS SPL      SEL        Peak
----------------------------------------------------------------------------------------------------------------
20 or 24 (51 or 61 cm) inch steel pile;              163  .........  .........  NMFS 2023.
 vibratory.
30 (76 cm) inch steel pile; vibratory........        166  .........  .........  NMFS 2023.
24 (61 cm) inch steel pile; impact...........        190        177        203  Caltrans 2015.
30 inch (76 cm) steel pile; impact...........        190        177        210  Caltrans 2015.
8 inch (20 cm) tension anchor (DTH) (for 24          156        144        170  NMFS 2022a; Reyff 2020.
 and 30 inch (61 or 76 cm) piles).
30 inch (76 cm) steel pile rock socketing            174        164        194  Denes et al. (2019); NMFS
 (DTH).                                                                          (2022a); Reyff and Heyvaert
                                                                                 (2019); Reyff (2020).
----------------------------------------------------------------------------------------------------------------

    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 x Log10 (R1/R2),

where

TL = transmission loss in dB
B = transmission loss coefficient
R1 = the distance of the modeled SPL from the driven 
pile, and
R2 = the distance from the driven pile of the initial 
measurement

    Absent site-specific acoustical monitoring with differing measured 
TL, a practical spreading value of 15 is used as the TL coefficient in 
the above formula. Site-specific TL data for the Killisnoo Harbor are 
not available; therefore, the default coefficient of 15 is used to 
determine the distances to the Level A harassment and Level B 
harassment thresholds.
    The ensonified area associated with Level A harassment is more 
technically challenging to predict due to the need to account for a 
duration component. Therefore, NMFS developed an optional User 
Spreadsheet tool to accompany the 2024 Updated Technical Guidance that 
can be used to relatively simply predict an isopleth distance for use 
in conjunction with marine mammal density or occurrence to help predict 
potential takes. We note that because of some of the assumptions 
included in the methods underlying this optional tool, we anticipate 
that the resulting isopleth estimates are typically going to be 
overestimates of some degree, which may result in an overestimate of 
potential take by Level A harassment. However, this optional tool 
offers the best way to estimate isopleth distances when more 
sophisticated modeling methods are not available or practical. For 
stationary sources pile driving, the optional User Spreadsheet tool 
predicts the distance at which, if a marine mammal remained at that 
distance for the duration of the activity, it would be expected to 
incur auditory injury. Inputs used in the optional User Spreadsheet 
tool, and the resulting estimated isopleths, are reported below in 
tables 6 and 7.

                                Table 6--NMFS User Spreadsheet Inputs for the Angoon Ferry Terminal Modifications Project
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                             Activity
                                                                             Weighting       duration       Strike rate      Number of       Number of
            Pile size and type                  Spreadsheet tab used          factor        (hours) per     per second      strikes per    piles per day
                                                                            adjustment         pile                            pile
--------------------------------------------------------------------------------------------------------------------------------------------------------
Vibratory removal:
    20 or 24 inch (51 or 61 cm) steel       A.1) Vibratory pile driving.             2.5            0.25              NA              NA             1-4
     piles (temporary or permanent).

[[Page 13477]]

 
Vibratory Installation:
    20 or 24 inch (51 or 61 cm) steel       A.1) Vibratory pile driving.             2.5            0.25              NA              NA             1-4
     piles (permanent).
    30 inch (76 cm) steel piles...........
Impact Installation:
    20 or 24 inch (51 or 61 cm) steel       E. 1) Impact pile driving...               2              NA              NA              50           0.5-4
     piles (permanent).
    30 inch (76 cm) steel piles...........
DTH:
    Rock socket (30 inch (76 cm)).........  E. 2) DTH pile driving......               2               8              10              NA          0.33-1
    8 inch (20 cm) tension anchor (for 20,                                                             4                                          0.33-2
     24 and 30 inch (51, 61, or 76 cm)
     piles).
--------------------------------------------------------------------------------------------------------------------------------------------------------


   Table 7--Level A Harassment and Level B Harassment Isopleths and Associated Areas From Vibratory Impact and DTH Pile Driving and Vibratory Removal
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                 Level A harassment zone (m) \a\, areas (km\2\) \b\                          Level B
                                             ------------------------------------------------------------------------------------------  harassment zone
               Pile size/type                                                                                                            (m) \a\,  areas
                                                LF Cetaceans      HF Cetaceans      VHF Cetaceans          PW                OW            (km\2\) \b\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Vibratory pile driving/removal:
    20 or 24 (51 or 61 cm) inch steel pile                12.5               4.8              10.2              16.1               5.1             7,356
     installation or removal................           (0.003)           (0.001)           (0.002)           (0.004)           (0.001)            (9.23)
    30 inch (76 cm) steel pile installation.              19.9               7.6              16.2              25.6               8.6            11,659
                                                       (0.005)           (0.002)           (0.004)           (0.007)           (0.002)           (18.61)
Impact pile driving:
    20 or 24 inch (51 or 61 cm) steel                    135.5              17.3             209.6             120.3              44.9             1,000
     installation...........................            (0.07)           (0.004)            (0.14)            (0.06)            (0.01)            (0.86)
    30 inch (76 cm) permanent installation..             135.5              17.3             209.6             120.3              44.9             1,000
                                                        (0.07)           (0.004)            (0.14)            (0.06)            (0.01)            (0.86)
DTH:
    8 inch (20 cm) tension anchor                        109.0              13.9             168.7              96.8              36.1             2,512
     installation (drilling)................            (0.05)           (0.003)            (0.10)            (0.04)            (0.01)            (2.39)
    30 inch (76 cm) steel installation (rock           2,348.3             299.6           3,634.0           2,086.1             777.6            39,811
     sockets)...............................            (2.23)            (0.22)            (3.42)            (2.02)            (0.64)           (20.26)
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Distances represent the calculated radius of the zone. The actual zone may be truncated by landforms.
\b\ Areas of zones accounting for truncation by landforms.

Marine Mammal Occurrence and Take Estimation

    In this section we provide information about the occurrence of 
marine mammals, including density or other relevant information which 
will inform the take calculations. We describe how the information 
provided is synthesized to produce a quantitative estimate of the take 
that is reasonably likely to occur and proposed for authorization.
    Available information regarding marine mammal occurrence in the 
vicinity of the project area includes site-specific and nearby survey 
information and historic data sets. Prior data sets included: (1) 
Cetacean Surveys conducted from vessels in Southeast Alaska between 
1991-2007 (Dahlheim 2009), (2) surveys for humpback whales from vessels 
in the Prince William Sound, Lynn Canal, and the Sitka Sound from 
August through March in 2007 through 2009 (Staley et al., 2018), (3) 
line transect surveys from vessels for Dall's and harbor porpoises from 
1991 through 1993, 2006 through 2007, and 2010 through 2012 and 2019 
(Jefferson et al., 2019, Dahlheim et al., 2015, and Zerbini et. al., 
2022), and (4) Land-based surveys conducted at Sitka's Whale Park 
completed weekly between September and May 1995-2000 (Straley and 
Pendell (2017).
    ADOT&PF used species-specific density occurrence information 
described above to estimate take of each species using one of three 
formulas provided here:
    (1) Incidental take estimate = group size x number of groups per 
day x days of pile driving activity (143 days)
    (2) Incidental take estimate = group size x number of groups per 
month (considered 30 days) x months of pile driving activity (143 days/
30 days per month)
    (3) Incidental take estimate = marine mammal density (animals/km2) 
x ensonified area (km2) for each pile driving activity x days of each 
pile driving activity, summed across all activities
    Minke Whale--Minke whales are generally rare in Southeast Alaska, 
including the Chatham Strait, and are often observed as single 
individuals (Dahlheim et al. 2009). NMFS estimates that up to one minke 
whale may occur within Level B harassment zone each month, and applied 
equation two above. Therefore, NMFS proposes to authorize 5 takes by 
Level B harassment of minke whales (1 animal x 1 group per month x 4.76 
months).

[[Page 13478]]

    For all project activities, ADOT&PF proposes to implement shutdown 
zones for low-frequency cetaceans that exceed the Level A harassment 
isopleths. Therefore, Level A harassment of minke whale from these 
activities is unlikely. However, given the large shutdown zone for rock 
socketing (2,350 m), NMFS anticipates that PSOs may not always be able 
to implement a shutdown at the farther extent of the zone. Therefore, 
NMFS anticipates that a minke whale could enter and remain within the 
Level A harassment zone long enough to incur auditory injury, and as 
requested by ADOT&PF, NMFS is proposing to authorize 1 take of minke 
whale by Level A harassment.
    Humpback Whale--Humpback whales are common in inland water of 
Southeast Alaska. They occur daily with an average group size two 
animals (Dahlheim et al. 2009). NMFS estimates that up to one group of 
two humpback whales would occur in the Level B harassment zone each day 
of the proposed construction activities, and applied equation 1 above. 
Therefore, NMFS proposes to authorize 286 takes by Level B harassment 
of humpback whales (2 animals x 1 group per day x 143 days). In the 
project area, the majority of whales (98 percent) are anticipated to be 
from the Hawaii DPS and 2 percent from the ESA-listed Mexico DPS (Wade 
2021; Muto et al. 2022). Therefore, of the 286 takes by Level B 
harassment, NMFS anticipates that 280 would be of individuals from the 
Hawaii DPS (Hawaii stock) and six takes would be of individuals from 
the Mexico DPS (Mexico-North Pacific stock).
    For all project activities, ADOT&PF proposes to implement shutdown 
zones for low-frequency cetaceans that exceed the Level A harassment 
isopleths. Therefore, Level A harassment of humpback whale from these 
activities is unlikely. However, given the large shutdown zone for rock 
socketing (2,350 m), NMFS anticipates that PSOs may not always be able 
to implement a shutdown at the farther extent of the zone. Therefore, 
NMFS anticipates that a humpback whale could enter and remain within 
the Level A harassment zone long enough to incur auditory injury on 
each project day where the shutdown zone extends to that distance 
(2,350 m; 9 days). Therefore, ADOT&PF requested, and NMFS is proposing 
to authorize, 9 take of humpback whale by Level A harassment. Of the 
nine takes by Level A harassment, NMFS anticipates that eight would be 
of individuals from the Hawaii DPS (Hawaii stock) and one of an 
individual from the Mexico DPS (Mexico-North Pacific stock).
    Killer Whale--Killer whales are commonly observed each month in 
Southeast Alaska inland waters, including the project action area. The 
three stocks that are most likely to occur in Southeast Alaska are the 
Eastern North Pacific Alaska Resident stock, Eastern North Pacific 
Northern Resident stock, and the West Coast Transient stock (Young et 
al. 2023). Mean group size for all seasons for residents is 24.4 
animals; for transients 4.9 animals (Dahlheim et al. 2009). NMFS 
anticipates that up to two groups of 25 killer whales may occur in the 
project area during each month of construction, and applied equation 2 
above. Therefore, NMFS proposes to authorize 238 takes of killer whales 
by Level B harassment (25 animals x 2 groups per month x 4.76 months).
    The largest Level A harassment zone for killer whales is 299.6 m 
during rock socketing. For all activities, ADOT&PF would implement 
shutdown zones that exceed the Level A harassment zone for HF 
cetaceans. Therefore, considering the small size of all Level A 
harassment zones and the proposed shutdown zone requirements, no take 
by Level A harassment of killer whales is anticipated or proposed for 
authorization.
    Pacific White-sided Dolphin--Pacific white-sided dolphins are 
generally rare in the project area but have been documented in the 
Chatham Strait. To avoid underestimating potential impacts from the 
project, NMFS estimates that up to one group may occur in the project 
area every other month (i.e., one group every 60 days). Pacific white-
sided dolphins typically occur in groups of 23-26 individuals (Dahlheim 
et al., 2009), but have been observed in southeast Alaska in groups of 
up to 153. Using the equation above would result in an estimate of 62 
takes by Level B harassment (26 animals x .5 groups per month x 4.76 
months). However, to account for the potential of a large group 
occurring in the Level B harassment zone, NMFS proposes to authorize 
153 takes by Level B harassment.
    The largest Level A harassment zone for Pacific white-sided 
dolphins is 299.6 m during rock socketing. For all activities, ADOT&PF 
would implement shutdown zones that exceed the Level A harassment zone 
for HF cetaceans. Therefore, considering the small size of all Level A 
harassment zones and the proposed shutdown zone requirements, no take 
by Level A harassment of Pacific white-sided dolphins is anticipated or 
proposed for authorization.
    Dall's Porpoise--Dall's porpoises are frequently observed in that 
Chatham Strait, including the proposed project area. Dall's porpoise 
typically occur in group sizes of less than five individuals with a 
mean group size of 3.13 individuals per group during spring, summer, 
and fall (Jefferson et al. 2019). The density of Dall's porpoise in 
Southeast Alaska was 0.189 animals per km\2\ (Jefferson et al. 2019). 
NMFS applied equation three above to estimate take of Dall's porpoise 
by Level B harassment. Therefore, NMFS proposes to authorize 173 takes 
by Level B harassment of Dall's porpoise (i.e., (0.189 animals/km\2\ x 
9.23 km\2\ x 42 days = 73.3) + (0.189 animals/km\2\ x 18.61 km\2\ x 11 
days = 39.0) + (0.189 animals/km\2\ x 0.86 km\2\ x 14 days = 2.3) + 
(0.189 animals/km\2\ x 0.86 km\2\ x 22 days = 3.6) + (0.189 animals/
km\2\ x 2.39 km\2\ x 45 days = 20.3) + (0.189 animals/km\2\ x 20.26 
km\2\ x 9 days = 34.5) = 173 takes by Level B harassment).
    For all project activities except rock socketing, ADOT&PF proposes 
to implement shutdown zones for very high-frequency cetaceans that 
exceed the Level A harassment isopleths. Therefore, Level A harassment 
of Dall's porpoise from these activities is unlikely. For rock 
socketing, the Level A harassment zone exceeds the shutdown zone, and 
NMFS anticipates that one group of 3 Dall's porpoise could enter and 
remain within the Level A harassment zone long enough to incur auditory 
injury on each of the 9 days of that activity. Therefore, NMFS is 
proposing to authorize 27 takes of Dall's porpoise by Level A 
harassment.
    Harbor Porpoise--Harbor porpoises have been infrequently observed 
in the south Chatham Strait, including the proposed action area. The 
density of harbor porpoise in Southeast Alaska was 0.106 animals per 
km\2\ (Zerbini et al., 2022). NMFS applied equation three above to 
estimate take of harbor porpoise by Level B harassment. Therefore, NMFS 
proposes to authorize 97 takes by Level B harassment of harbor porpoise 
(i.e., (0.106 animals/km\2\ x 9.23 km\2\ x 42 days=41.1) + (0.106 
animals/km\2\ x 18.61 km\2\ x 11 days = 21.7) + (0.106 animals/km\2\ x 
0.86 km\2\ x 14 days = 1.3) + (0.106 animals/km\2\ x 0.86 km\2\ x 22 
days = 2.0) + (0.106 animals/km\2\ x 2.39 km\2\ x 45 days = 11.4) + 
(0.106 animals/km\2\ x 20.26 km\2\ x 9 days = 19.3) = 97 takes by Level 
B harassment).
    For all project activities except rock socketing, ADOT&PF proposes 
to implement shutdown zones for very high-frequency cetaceans that 
exceed the Level A harassment isopleths. Therefore, Level A harassment 
of harbor

[[Page 13479]]

porpoise from these activities is unlikely. For rock socketing, the 
Level A harassment zone exceeds the shutdown zone, and NMFS anticipates 
that one group of five harbor porpoise could enter and remain within 
the Level A harassment zone long enough to incur auditory injury on 
each of the 9 days of that activity. Therefore, NMFS is proposing to 
authorize 45 takes of harbor porpoise by Level A harassment.
    Harbor Seal--Harbor seals are observed daily in the Chatham Strait. 
They typically occur in groups of one to four individuals (Jefferson et 
al., 2019). NMFS estimates that up to two groups of three seals could 
occur in the project area each day, and applied equation 1 above. 
Therefore NMFS proposes to authorize 858 takes by Level B harassment of 
harbor seals (3 animals x 2 groups per day x 143 days).
    For all project activities except rock socketing, ADOT&PF proposes 
to implement shutdown zones for phocids that exceed the Level A 
harassment isopleths. Therefore, Level A harassment of harbor seal from 
these activities is unlikely. For rock socketing, the Level A 
harassment zone exceeds the shutdown zone, and NMFS anticipates that up 
to two groups of three harbor seals could enter and remain within the 
Level A harassment zone long enough to incur auditory injury on each of 
the 9 days of that activity. Therefore, NMFS is proposing to authorize 
54 takes of harbor seal by Level A harassment.
    Steller Sea Lion--Steller sea lions are observed in the project 
area every month. They typically occur in groups of one to four 
individuals (NMFS 2023). To avoid potentially underestimating take, 
NMFS estimates that up to two groups of two Steller sea lions could 
occur in the Level B harassment zone each day, and applied equation 1 
above (2 animals x 2 group per day x 143 days). Therefore, NMFS is 
proposing to authorize 572 takes by Level B harassment of Steller sea 
lion. NMFS estimates that the majority of Steller sea lions in the 
project area (98.6 percent) would be from the Eastern DPS and 1.4 
percent would be from the Western DPS (Hastings et al., 2020). 
Therefore, of the 572 takes by Level B harassment, NMFS anticipates 564 
takes would be of individuals from the Eastern DPS and 8 from the 
Western DPS.
    For all project activities except rock socketing, ADOT&PF proposes 
to implement shutdown zones for otariids that exceed the Level A 
harassment isopleths. Therefore, Level A harassment of Steller sea lion 
from these activities is unlikely. For rock socketing, the Level A 
harassment zone exceeds the shutdown zone, and NMFS anticipates that up 
to one Steller sea lion could enter and remain within the Level A 
harassment zone long enough to incur auditory injury on each of the 9 
days of that activity. Given the expected occurrence of Western vs 
Eastern DPS Steller sea lions in the area, none of these takes are 
anticipated to be of Western DPS animals. Therefore, NMFS is proposing 
to authorize 9 takes of Eastern DPS Steller sea lion by Level A 
harassment. A summary of estimated take by Level A and Level B 
harassment is provided in table 8.

                                     Table 8--Estimated Take by Level A and Level B Harassment, by Species and Stock
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                       Level A         Level B     Total proposed    Proposed take as a
            Common name                      Stock           Stock abundance \a\     harassment      harassment         take        percentage of stock
--------------------------------------------------------------------------------------------------------------------------------------------------------
Minke whale........................  Alaska...............  Undetermined.........               1               5               6  Undetermined.
Humpback whale.....................  Hawaii (Hawaii DPS)..  11,278...............               8             280             288  2.6.
                                     Mexico-North Pacific   Undetermined.........               1               6               7  Undetermined.
                                      (Mexico DPS).
Killer whale.......................  Eastern North Pacific  1,920................               0             238             238  12.4.\b\
                                      Alaska Resident.
                                     West Coast Transient.  349..................                                                  68.2.\b\
                                     Eastern North Pacific  302..................                                                  78.8.\b\
                                      Northern Resident.
Pacific white-sided dolphin........  North Pacific........  26,880...............               0             153             153  Less than 1.
Dall's porpoise....................  Alaska...............  Undetermined.........              27             173             200  Undetermined.
Harbor porpoise....................  Northern Southeast     1,619................              45              97             142  8.8.
                                      Alaska Inland Waters.
Harbor seal........................  Sitka/Chatham Strait.  13,289...............              54             858             912  6.9.
Steller sea lion...................  Western DPS..........  49,837...............               0               8               8  Less than 1.
                                     Eastern DPS..........  36,308...............               9             564             573  1.6.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Stock size is Nbest according to NMFS 2023 SARs.
\b\ NMFS conservatively assumed that all takes could occur to each stock.

Proposed Mitigation

    In order to issue an IHA under section 101(a)(5)(D) of the MMPA, 
NMFS must set forth the permissible methods of taking pursuant to the 
activity, and other means of effecting the least practicable impact on 
the species or stock and its habitat, paying particular attention to 
rookeries, mating grounds, and areas of similar significance, and on 
the availability of the species or stock for taking for certain 
subsistence uses (latter not applicable for this action). NMFS 
regulations require applicants for incidental take authorizations to 
include information about the availability and feasibility (economic 
and technological) of equipment, methods, and manner of conducting the 
activity or other means of effecting the least practicable adverse 
impact upon the affected species or stocks, and their habitat (50 CFR 
216.104(a)(11)).
    In evaluating how mitigation may or may not be appropriate to 
ensure the least practicable adverse impact on species or stocks and 
their habitat, as well as subsistence uses where applicable, NMFS 
considers 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

[[Page 13480]]

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, and impact on 
operations.
    The mitigation measures described in the following paragraphs would 
apply to all in-water construction activities for the Angoon Ferry 
Modifications project.

Shutdown Zones and Monitoring

    ADOT&PF must establish shutdown zones for all pile driving 
activates. The purpose of a shutdown zone is generally to define an 
area within which shutdown of the activity would occur upon sighting of 
a marine animal (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, as shown in table 9. A minimum shutdown 
zone of 10 m would be required for all in-water construction activities 
to avoid physical interaction with marine mammals. Marine mammal 
monitoring would be conducted during all pile driving activities to 
ensure that shutdowns occur, as required. Proposed shutdown zones for 
each activity type are shown in table 9.
    Prior to the start of any pile driving, ADOT&PF would establish 
shutdown zones for construction activities (table 9). Protected species 
observers (PSO) would survey the shutdown zones for at least 30 minutes 
before pile driving activities start. If marine mammals are observed 
within the shutdown zone, pile driving, tension anchoring, or rock 
socketing will be delayed until the animal has moved out of the 
shutdown zone, either verified by a PSO or by waiting until 15 minutes 
has elapsed without a sighting of small cetaceans, and pinnipeds; or 30 
minutes has elapsed without a sighting of a large cetacean. If a marine 
mammal approaches or enters the shutdown zone during pile driving, 
tension anchoring, or rock socketing, the activity would be halted. 
Pile-driving would not re-commence until all marine mammals are assumed 
to have cleared these established shutdown zones as described above. If 
a species for which authorization has not been granted, or a species 
which has been granted but the authorized takes are met, is observed 
approaching or within the Level B harassment zone during pile driving, 
pile removal, or tension anchoring, the activity would be halted. Pile 
driving may resume after the animal has moved out of and is moving away 
from the shutdown zone (or Level B harassment zone for a species for 
which take is not authorized, or a species for take is authorized but 
the authorized takes are met) or after at least 15 minutes has passed 
since the last observation of the animal.
    All marine mammals would be monitored in the Level B harassment 
zones and throughout the area as far as visual monitoring can take 
place. If a marine mammal enters the Level B harassment zone, in-water 
activities would continue and PSOs would document the animal's presence 
within the estimated harassment zone.

                                            Table 9--Shutdown Zones and Level B Harassment Zones by Activity
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                              Minimum shutdown zone (m)                                      Level B
                  Activity                   ------------------------------------------------------------------------------------------  harassment zone
                                                LF Cetaceans      HF Cetaceans      VHF Cetaceans        Phocids          Otariids             (m)
--------------------------------------------------------------------------------------------------------------------------------------------------------
    Barge movements, pile positioning, etc..                10                10                10                10                10  ................
Vibratory pile driving/removal:
    20 or 24 (51 or 61 cm) inch temporary                   15                10                15                20                10             7,360
     and permanent pile installation or
     removal................................
    30 inch (76 cm) steel permanent                         20                10                20                30                10            11,660
     installation...........................
Impact pile driving:
    20 or 24 inch (51 or 61 cm) steel                      140                20               210               120                45             1,000
     permanent installation.................
    30 inch (76 cm) steel permanent                        140                20               210               120                45             1,000
     installation...........................
DTH (Tension anchoring and rock sockets):
    8 inch (20 cm) tension anchor                          110                15               170               100                40             2,515
     installation...........................
    30 inch (76 cm) steel permanent                      2,350               300               400               400               400            12,865
     installation...........................
--------------------------------------------------------------------------------------------------------------------------------------------------------

Protected Species Observers

    The monitoring locations for all protected species observers (PSOs) 
during all pile driving activities (described in the Proposed 
Monitoring and Reporting Section) would ensure that the entirety of all 
shutdown zones are visible, except potentially the outer extent of the 
zone for LF cetaceans during rock socketing. PSOs would monitor the 
shutdown zones and as much of the Level B harassment zones as possible. 
Monitoring enables observers to be aware of and communicate the 
presence of marine mammals in the project areas outside the shutdown 
zones and thus prepare for a potential cessation of activity should the 
animal enter the shutdown zone.

Pre- and Post-Activity Monitoring

    Monitoring must take place from 30 minutes prior to initiation of 
pile driving activities (i.e., pre-clearance monitoring) through 30 
minutes post-completion of pile driving. Prior to the start of daily 
in-water construction activity, or whenever a break in pile driving of 
30 minutes or longer occurs, PSOs would observe the shutdown and 
monitoring zones for a period of 30 minutes. The shutdown zone would be 
considered cleared when a marine mammal has not been observed within 
the zone for a 30-minute period. If a marine mammal is observed within 
the shutdown zones, pile driving activity would be delayed or halted. 
If work ceases for more than 30 minutes, the pre-activity monitoring of 
the shutdown zones would commence. A determination that the shutdown 
zone is clear must be made during a period of good visibility (i.e., 
the entire shutdown zone and surrounding waters must be visible to the 
naked eye).

Soft Start

    Soft-start procedures are used to provide additional protection to 
marine mammals by providing warning and/or giving marine mammals a 
chance to

[[Page 13481]]

leave the area prior to the hammer operating at full capacity. For 
impact pile driving, ADOT&PF would be required to provide an initial 
set of three strikes from the hammer at reduced energy, followed by a 
30-second waiting period, then two subsequent reduced- energy strike 
sets. Soft start would 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.
    Based on our evaluation of the applicant's proposed measures, NMFS 
has preliminarily determined that the proposed mitigation measures 
provide the means of effecting the least practicable impact on the 
affected species or stocks and their habitat, paying particular 
attention to rookeries, mating grounds, and areas of similar 
significance.

Proposed Monitoring and Reporting

    In order to issue an IHA for an activity, section 101(a)(5)(D) of 
the MMPA states that NMFS must set forth requirements pertaining to the 
monitoring and reporting of such taking. The MMPA implementing 
regulations at 50 CFR 216.104(a)(13) indicate that requests for 
authorizations must include the suggested means of accomplishing the 
necessary monitoring and reporting that will result in increased 
knowledge of the species and of the level of taking or impacts on 
populations of marine mammals that are expected to be present while 
conducting the activities. Effective reporting is critical both to 
compliance as well as ensuring that the most value is obtained from the 
required monitoring.
    Monitoring and reporting requirements prescribed by NMFS should 
contribute to improved understanding of one or more of the following:
     Occurrence of marine mammal species or stocks in the area 
in which take is anticipated (e.g., presence, abundance, distribution, 
density);
     Nature, scope, or context of likely marine mammal exposure 
to potential stressors/impacts (individual or cumulative, acute or 
chronic), through better understanding of: (1) action or environment 
(e.g., source characterization, propagation, ambient noise); (2) 
affected species (e.g., life history, dive patterns); (3) co-occurrence 
of marine mammal species with the activity; or (4) biological or 
behavioral context of exposure (e.g., age, calving or feeding areas);
     Individual marine mammal responses (behavioral or 
physiological) to acoustic stressors (acute, chronic, or cumulative), 
other stressors, or cumulative impacts from multiple stressors;
     How anticipated responses to stressors impact either: (1) 
long-term fitness and survival of individual marine mammals; or (2) 
populations, species, or stocks;
     Effects on marine mammal habitat (e.g., marine mammal prey 
species, acoustic habitat, or other important physical components of 
marine mammal habitat); and,
     Mitigation and monitoring effectiveness.

Visual Monitoring

    Marine mammal monitoring must be conducted in accordance with the 
Marine Mammal Monitoring and Mitigation Plan and section 5 of the IHA. 
ADOT&PF's draft Marine Mammal Monitoring and Mitigation Plan is 
Appendix B of the IHA application.
    Marine mammal monitoring during pile driving activities would be 
conducted by PSOs meeting NMFS' standards and in a manner consistent 
with the following:
     PSOs must be independent of the activity contractor (for 
example, employed by a subcontractor) and have no other assigned tasks 
during monitoring periods;
     At least one PSO would have prior experience performing 
the duties of a PSO during construction activity pursuant to a NMFS-
issued incidental take authorization;
     Other PSOs may substitute 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 incidental take authorization. PSOs may also substitute Alaska 
native traditional knowledge for experience;
     Where a team of three or more PSOs is required, a lead 
observer or monitoring coordinator would 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 
activities subject to this IHA.
    PSOs should have the following additional qualifications:
     Ability to conduct field observations and collect data 
according to assigned protocols;
     Experience or training in the field identification of 
marine mammals, including the identification of behaviors;
     Sufficient training, orientation, or experience with the 
construction operation to provide for personal safety during 
observations;
     Writing skills sufficient to prepare a report of 
observations including but not limited to the number and species of 
marine mammals observed; dates and times when in-water construction 
activities were conducted; dates, times, and reason for implementation 
of mitigation (or why mitigation was not implemented when required); 
and marine mammal behavior; and
     Ability to communicate orally, by radio or in person, with 
project personnel to provide real-time information on marine mammals 
observed in the area as necessary.
    During all pile driving activities, a minimum of two PSOs will 
monitor shutdown zones during pile driving activities. PSOs will 
establish monitoring locations as described in the Marine Mammal 
Mitigation and Monitoring Plan. Monitoring locations would be selected 
by the contractor during pre-construction. PSOs would monitor for 
marine mammals entering the Level B harassment zones; the position(s) 
may vary based on construction activity and location of piles or 
equipment.
    Monitoring would be conducted 30 minutes before, during, and 30 
minutes after pile driving/removal activities. In addition, observers 
shall record all incidents of marine mammal occurrence, regardless of 
distance from activity, and shall document any behavioral reactions in 
concert with distance from piles being driven or removed. Pile driving/
removal activities include the time to install or remove a single pile 
or series of piles, as long as the time elapsed between uses of the 
pile driving equipment is no more than 30 minutes.

Data Collection

    PSOs would use approved data forms to record the following 
information:
     Dates and times (beginning and end) of all marine mammal 
monitoring; and
     PSO locations during marine mammal monitoring.
     Construction activities occurring during each daily 
observation period, including how many and what type of piles were 
driven or removed and by what method (i.e., vibratory, impact, tension 
anchoring, or rock socketing).
     Weather parameters and water conditions;
     The number of marine mammals observed, by species, 
relative to the pile location and if pile driving or removal was 
occurring at time of sighting;

[[Page 13482]]

     Distance and bearings of each marine mammal observed to 
the pile being driven or removed;
     Description of marine mammal behavior patterns, including 
direction of travel;
     Age and sex class, if possible, of all marine mammals 
observed; and
     Detailed information about implementation of any 
mitigation triggered (such as shutdowns and delays), a description of 
specific actions that ensued, and resulting behavior of the animal if 
any.

Reporting

    A draft marine mammal monitoring report would be submitted to NMFS 
within 90 days after the completion of pile driving activities, or 60 
days prior to a requested date of issuance of any future IHAs for the 
project, or other projects at the same location, whichever comes first. 
The marine mammal report would include an overall description of work 
completed, a narrative regarding marine mammal sightings, and 
associated PSO data sheets. Specifically, the report would include:
     Dates and times (begin and end) of all marine mammal 
monitoring;
     Construction activities occurring during each daily 
observation period, including the number and type of piles driven or 
removed and by what method (i.e., impact, vibratory, tension 
anchoring). The total duration of driving time must be recorded for 
each pile during vibratory driving and, number or strikes for each pile 
during impact driving, and the duration of operation of drilling and 
components for tension anchoring;
     PSO locations during marine mammal monitoring;
     Environmental conditions during monitoring periods (at 
beginning and end of PSO shift and whenever conditions change 
significantly), including Beaufort sea state and any other relevant 
weather conditions including cloud cover, fog, sun glare, and overall 
visibility to the horizon, and estimated observable distance;
     Upon observation of a marine mammal, the following 
information: (1) name of PSO who sighted the animal(s) and PSO location 
and activity at time of sighting; (2) time of sighting; (3) 
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; (4) 
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); (5) estimated number of animals (min/max/best 
estimate); (6) estimated number of animals by cohort (adults, 
juveniles, neonates, group composition, etc.); (7) animal's closest 
point of approach and estimated time spent within the harassment zone; 
and (8) description of any marine mammal behavioral observations (e.g., 
observed behaviors such as feeding or traveling), including an 
assessment of behavioral responses thought to have resulted from the 
activity (e.g., no response or changes in behavioral state such as 
ceasing feeding, changing direction, flushing, or breaching);
     Number of marine mammals detected within the harassment 
zones, by species; and
     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.
    If no comments are received from NMFS within 30 days, the draft 
reports would constitute the final reports. If comments are received, a 
final report addressing NMFS' comments would be required to be 
submitted within 30 days after receipt of comments. All PSO datasheets 
and/or raw sighting data would be submitted with the draft marine 
mammal report.

Reporting Injured or Dead Marine Mammals

    In the event that personnel involved in the construction activities 
discover an injured or dead marine mammal, ADOT&PF shall report the 
incident to the Office of Protected Resources, NMFS and to the Alaska 
regional stranding network as soon as feasible. If the death or injury 
was clearly caused by the specified activity, ADOT & PF must 
immediately cease the specified activities until NMFS is able to review 
the circumstances of the incident and determine what, if any, 
additional measures are appropriate to ensure compliance with the terms 
of the IHA. The IHA-holder must not resume their activities until 
notified by NMFS. The report must include the following information:
     Time, date, and location (latitude/longitude) of the first 
discovery (and updated location information if known and applicable);
     Species identification (if known) or description of the 
animal(s) involved;
     Condition of the animal(s) (including carcass condition if 
the animal is dead);
     Observed behaviors of the animal(s), if alive;
     If available, photographs or video footage of the 
animal(s); and,
     General circumstances under which the animal was 
discovered.

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 impacts or responses (e.g., intensity, duration), 
the context of any impacts or responses (e.g., critical reproductive 
time or location, foraging impacts affecting energetics), 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 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, the majority of our analysis applies to all 
the species listed in table 2, given that many of the anticipated 
effects of this project on different marine mammal stocks are expected 
to be relatively 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, they are described independently in the analysis below.
    Pile driving and removal, tension anchoring, and rock socketing 
have the potential to disturb or displace marine mammals. Specifically 
the project activities may result in take, in the form of Level A 
harassment (minke whale, humpback whale, Dall's porpoise, harbor 
porpoise, harbor seal, and Steller

[[Page 13483]]

sea lion only) and Level B harassment from underwater sounds generated 
from pile driving and removal, tension anchoring, and rock socketing. 
Potential takes could occur if individuals are present in the 
ensonified zone when these activities are underway.
    The takes by Level B harassment would be due to potential 
behavioral disturbance and TTS. Takes by Level A harassment would be 
due to auditory injury. No mortality or serious injury is anticipated 
given the nature of the activity, even in the absence of the required 
mitigation. The potential for harassment is minimized through the 
construction method and the implementation of the proposed mitigation 
measures (see Proposed Mitigation Measures section).
    Take would occur within a limited, confined area (Killisnoo Harbor) 
of the stocks' ranges. The intensity and duration of take by Level A 
harassment and Level B harassment would be minimized through use of 
mitigation measures described herein. Further, the project is not 
anticipated to impact any known important habitat areas for any marine 
mammal species with the exception of a known biologically important 
area for humpback whales, discussed below.
    Take by Level A harassment is proposed for authorization 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. Any take by Level A 
harassment is expected to arise from, at most, a small degree of 
auditory injury 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 auditory injury. 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 auditory injury or TTS potentially incurred 
here would not be expected to adversely impact individual fitness, let 
alone annual rates of recruitment or survival.
    Behavioral responses of marine mammals to pile driving at the 
project site, if any, are expected to be mild and temporary. Marine 
mammals within the Level B harassment zone may not show any visual cues 
they are disturbed by activities or 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 the limited number of 
piles to be installed or extracted per day and that pile driving and 
removal would occur across a maximum of 143 days within the 12-month 
authorization period, any harassment would be temporary.
    Any impacts on marine mammal prey that would occur during ADOT&PF's 
proposed activity would 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 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 elevated noise in a small, 
localized area of habitat would have any effect on 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 would therefore not result in population-level impacts.
    The waters of the Chatham Strait are part of the Alaska humpback 
whale feeding BIA (Wild et al., 2023). However, underwater sound would 
be constrained to Killisnoo Harbor and would be truncated by land 
masses. The area of the BIA that may be affected by the proposed 
project is small relative to the overall area of the BIA. The humpback 
whale feeding BIA is active between May and October while the proposed 
project is scheduled to occur from May 2026 through April 2027. 
Although the construction period overlaps when the humpback whale BIA 
is active, construction activities are only expected to occur for 143 
non-consecutive days over one year period. Underwater sounds produced 
from proposed construction activities would only effect a small 
proportion of the BIA. Therefore, the proposed project is not expected 
to have significant adverse effects on humpback whales foraging in 
Alaska.
    The closest harbor seal haul out to the proposed project is 
approximately 12 km away in Hood Bay, and the closest Steller sea lion 
haul out is 20 km away at Point Lull. Each of these haulouts are 
located outside of the ensonified area for this project, and the 
project is not expected to have adverse effects on these haulout sites. 
No areas of specific biological importance (e.g., ESA critical habitat, 
other BIAs, or other areas) for any other species are known to overlap 
the project area.
    In summary and as described above, the following factors primarily 
support our preliminary determination that the impacts resulting from 
this activity are not expected to adversely affect any of the species 
or stocks through effects on annual rates of recruitment or survival:
     No serious injury or mortality is anticipated or 
authorized;
     For killer whale, Pacific white-sided dolphin, and the 
Western stock of Steller sea lions, no Level A harassment is 
anticipated or proposed for authorization;
     The intensity of anticipated takes by Level B harassment 
is relatively low for all stocks and would not be of a duration or 
intensity expected to result in impacts on reproduction or survival;
     The lack of anticipated significant or long-term negative 
effects to marine mammal habitat;
     With the exception of the humpback whale BIA described 
above, no areas of specific biological importance (e.g., ESA critical 
habitat, other BIAs, or other areas) for any other species are known to 
co-occur with the project area; and
     ADOT&PF would implement mitigation measures, such as soft-
starts for impact pile driving and shutdowns to minimize the numbers of 
marine mammals exposed to injurious levels of sound, and to ensure that 
take by Level A harassment, is at most, a small degree of auditory 
injury.
    Based on the analysis contained herein of the likely effects of the 
specified activity on marine mammals and their habitat, and taking into 
consideration the implementation of the proposed monitoring and 
mitigation measures, NMFS preliminarily finds that the total marine 
mammal take from the proposed activity will have a negligible impact on 
all affected marine mammal species or stocks.

Small Numbers

    As noted previously, only take of small numbers of marine mammals 
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

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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 amount of take NMFS is proposing to authorize is below one-
third of the estimated stock abundance of all species and stocks. For 
all stocks other than the West Coast Transient and Eastern North 
Pacific Northern Resident stocks of killer whale, the number of takes 
proposed for authorization would be considered small relative to the 
relevant stocks' abundances, even in the unlikely scenario that each 
estimated taking occurred to a new individual.
    The West Coast Transient stock of killer whale occurs from 
California through Southeast Alaska, and the Eastern North Pacific 
Northern Resident stock of killer whale occurs from Washington State 
through part of Southeast Alaska. Movements of killer whales, for both 
transient and resident stocks, between widely separated geographical 
areas have been documented. However, given the relatively sheltered 
location of the project site in inland waters of southeast Alaska, it 
is unlikely that numerous discrete groups of individuals sufficient to 
exceed one-third of the stock abundance would occur within the 
immediate vicinity of the project. It is more likely that individual 
groups that occur in the area would remain for periods of time and 
potentially be resighted on multiple days. As such, and given that the 
proposed takes would be allocated among three distinct killer whale 
stocks, the numbers of individuals taken would likely comprise less 
than one-third of the best available population abundance estimate of 
both the West Coast Transient and the Eastern North Pacific Northern 
Resident stocks of killer whale.
    There are no valid abundance estimates available for humpback whale 
(Mexico-North Pacific stock), minke whale (Alaska stock), or Dall's 
porpoise (Alaska stock). There is no recent stock abundance estimate 
for the Mexico-North Pacific stock of humpback whale and the minimum 
population is considered unknown (Young et al., 2024). There are two 
minimum population estimates for this stock that are over 15 years old: 
2,241 (Mart[iacute]nez-Aguilar, 2011) and 766 (Wade, 2021). Using 
either of these estimates, the seven total takes proposed for 
authorization (six by Level B harassment, one by Level A harassment) 
represent small numbers of the stock. There is also no current 
abundance estimate of the Alaska stock of minke whale, but an abundance 
of 2,020 individuals was estimated on the eastern Bering shelf based on 
a 2010 survey (Friday et al., 2013; Young et al., 2024). Therefore, the 
six takes proposed for authorization (five by Level B harassment, one 
by Level A harassment) represent small numbers of this stock, even if 
each take occurred to a new individual.
    The most recent stock abundance estimate of the Alaska stock of 
Dall's porpoise was 83,400 animals and, although the estimate is more 
than 8 years old, it is unlikely this stock has drastically declined 
since that time. Therefore, the 200 takes proposed for authorization 
(173 by Level B harassment, 27 by Level A harassment), represent small 
numbers of this stock.
    Based on the analysis contained herein of the proposed activity 
(including the proposed mitigation and monitoring measures) and the 
anticipated take of marine mammals, NMFS preliminarily finds that small 
numbers of marine mammals would 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 
Alaskan 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.
    The Kootznoowoo Tlingit tribe of Admiralty Island traditionally 
traded fur and harvested marine mammals. Today, much of the population 
engages in a commercial fishing and/or subsistence lifestyle with 98 
percent of households reporting use of some type of subsistence 
resource in 2012, the last year for which data is available (ADF&G 
2024f). About 10 percent of Angoon households attempted harvest of 
marine mammals, and 41 percent of households report using marine 
mammals, mostly harbor seals. No sea lion harvest was reported in the 
community in 2012.
    This project would occur in Killisnoo Harbor, and subsistence 
hunting of marine mammals does not occur in the project area; 
therefore, there are no relevant subsistence uses of marine mammals 
adversely impacted by this action. The proposed project is not likely 
to adversely impact the availability of any marine mammal species or 
stocks that are commonly used for subsistence purposes or to impact 
subsistence harvest of marine mammals in the region.
    Based on the description of the specified activity and the proposed 
mitigation and monitoring measures, NMFS has preliminarily determined 
that there will not be an unmitigable adverse impact on subsistence 
uses from ADOT&PF's proposed activities.

Endangered Species Act

    Section 7(a)(2) of the ESA of 1973 (16 U.S.C. 1531 et seq.) 
requires that each Federal agency insure that any action it authorizes, 
funds, or carries out is not likely to jeopardize the continued 
existence of any endangered or threatened species or result in the 
destruction or adverse modification of designated critical habitat. To 
ensure ESA compliance for the issuance of IHAs, NMFS' Office of 
Protected Resources (OPR) consults internally whenever we propose to 
authorize take for endangered or threatened species, in this case with 
the Alaska Regional Office (AKRO).
    NMFS is proposing to authorize take of humpback whale (Mexico DPS) 
and Steller sea lion (Western DPS), which are listed under the ESA. OPR 
has requested initiation of section 7 consultation with AKRO for the 
issuance of this IHA. NMFS will conclude the ESA consultation prior to 
reaching a determination regarding the proposed issuance of the 
authorization.

Proposed Authorization

    As a result of these preliminary determinations, NMFS proposes to 
issue an IHA to ADOT&PF for conducting the Angoon Ferry Terminal 
Modification Project in Angoon, Alaska from May 1, 2026 through April 
30, 2027, provided the previously mentioned mitigation, monitoring, and 
reporting requirements are incorporated. A draft of the proposed IHA 
can be found at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities.

[[Page 13485]]

Request for Public Comments

    We request comment on our analyses, the proposed authorization, and 
any other aspect of this notice of proposed IHA for the proposed 
construction project. We also request comment on the potential renewal 
of this proposed IHA as described in the paragraph below. Please 
include with your comments any supporting data or literature citations 
to help inform decisions on the request for this IHA or a subsequent 
renewal IHA.
    On a case-by-case basis, NMFS may issue a one-time, 1-year renewal 
IHA following notice to the public providing an additional 15 days for 
public comments when (1) up to another year of identical or nearly 
identical activities as described in the Description of Proposed 
Activity section of this notice is planned or (2) the activities as 
described in the Description of Proposed Activity section of this 
notice would not be completed by the time the IHA expires and a renewal 
would allow for completion of the activities beyond that described in 
the Dates and Duration section of this notice, provided all of the 
following conditions are met:
     A request for renewal is received no later than 60 days 
prior to the needed renewal IHA effective date (recognizing that the 
renewal IHA expiration date cannot extend beyond 1 year from expiration 
of the initial IHA).
     The request for renewal must include the following:
    (1) An explanation that the activities to be conducted under the 
requested renewal IHA are identical to the activities analyzed under 
the initial IHA, are a subset of the activities, or include changes so 
minor (e.g., reduction in pile size) that the changes do not affect the 
previous analyses, mitigation and monitoring requirements, or take 
estimates (with the exception of reducing the type or amount of take).
    (2) A preliminary monitoring report showing the results of the 
required monitoring to date and an explanation showing that the 
monitoring results do not indicate impacts of a scale or nature not 
previously analyzed or authorized.
     Upon review of the request for renewal, the status of the 
affected species or stocks, and any other pertinent information, NMFS 
determines that there are no more than minor changes in the activities, 
the mitigation and monitoring measures will remain the same and 
appropriate, and the findings in the initial IHA remain valid.

    Dated: March 18, 2025.
Catherine Marzin,
Acting Director, Office of Protected Resources, National Marine 
Fisheries Service.
[FR Doc. 2025-04902 Filed 3-21-25; 8:45 am]
BILLING CODE 3510-22-P