Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to Pier Maintenance and Bank Stabilization at U.S. Coast Guard Air Station Port Angeles, Port Angeles, Washington, 61549-61572 [2023-19327]

Agencies

• DEPARTMENT OF COMMERCE
• National Oceanic and Atmospheric Administration

[Federal Register Volume 88, Number 172 (Thursday, September 7, 2023)]
[Notices]
[Pages 61549-61572]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-19327]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

[RTID 0648-XD106]


Takes of Marine Mammals Incidental to Specified Activities; 
Taking Marine Mammals Incidental to Pier Maintenance and Bank 
Stabilization at U.S. Coast Guard Air Station Port Angeles, Port 
Angeles, Washington

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 U.S. Coast Guard (Coast 
Guard or USCG) for authorization to take marine mammals incidental to 
pier maintenance and bank stabilization construction activities at USCG 
Air Station Port Angeles, Port Angeles, Washington. 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, one-year renewal 
that could be issued under certain circumstances and if all 
requirements are met, as described in Request for Public Comments at 
the end of this notice. NMFS will consider public comments prior to 
making any final decision on the issuance of the requested MMPA 
authorization and agency responses will be summarized in the final 
notice of our decision.

DATES: Comments and information must be received no later than October 
10, 2023.

ADDRESSES: Comments should be addressed to Jolie Harrison, Chief, 
Permits and Conservation Division, Office of Protected Resources (OPR), 
NMFS, and should be submitted via email to [email protected].
    Instructions: NMFS is not responsible for comments sent by any 
other method, to any other address or individual, or received after the 
end of the comment period. Comments, 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 
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. 
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.

FOR FURTHER INFORMATION CONTACT: Cara Hotchkin, OPR, 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

[[Page 61550]]

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 mitigation, 
monitoring and reporting of the takings are set forth. The definitions 
of all applicable MMPA statutory terms cited above are included in the 
relevant sections below.

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 NOAA Administrative Order 216-
6A, which do not individually or cumulatively have the potential for 
significant impacts on the quality of the human environment and for 
which we have not identified any extraordinary circumstances that would 
preclude this categorical exclusion. Accordingly, NMFS has 
preliminarily determined that the issuance of the proposed IHA 
qualifies to be categorically excluded from further NEPA review.
    We will review all comments submitted in response to this notice 
prior to concluding our NEPA process or making a final decision on the 
IHA request.

Summary of Request

    On August 9, 2022, NMFS received a request from Coast Guard for an 
IHA to take marine mammals incidental to construction during pier 
maintenance activities at USCG Air Station Port Angeles in Port 
Angeles, Washington. Following NMFS' review of the application, Coast 
Guard submitted revised versions on May 11, 2023 and July 14, 2023. The 
application was deemed adequate and complete on July 18, 2023. Coast 
Guard's request is for take of five species of marine mammals by Level 
B harassment only. Neither Coast Guard nor NMFS expect serious injury 
or mortality to result from this activity and, therefore, an IHA is 
appropriate.

Description of Proposed Activity

Overview

    The Coast Guard proposes to conduct pier maintenance and bank 
stabilization on a portion of the shoreline at USCG Air Station Port 
Angeles in Port Angeles, Washington. The proposed work may result in 
the incidental take of marine mammals by Level B harassment due to 
exposure to underwater sound produced during impact and vibratory pile 
driving.
    The purpose of this project is to repair existing facilities and to 
protect vital mission support infrastructure from continued tidal 
action erosion and storm events. This project will repair up to 372 
feet (ft) (113.4 meters (m)) of eroded riprap shoreline, replace 37 
degraded timber piles with steel piles, repair up to 98 timber piles, 
permanently remove 11 abandoned timber piles and 3 steel camel barrier 
piles, and demolish 2 camels.

Dates and Duration

    The proposed IHA would be effective from November 15, 2023 to 
November 14, 2024. In-water work is expected to take approximately 15 
days and will occur during daylight hours during the lowest possible 
tide conditions. The U.S. Army Corps of Engineers has designated an in-
water work window between July 16 and February 15 to protect anadromous 
fishes. Work on this project may occur between November 15, 2023 and 
February 15, 2024 and from July 16, 2024 to November 14, 2024. In-water 
pile driving work would occur during daylight hours only at the lowest 
possible tide conditions.

Specific Geographic Region

    This project is located at USCG Air Station Port Angeles, in Port 
Angeles, Washington. USCG Air Station Port Angeles is located on the 
south-facing side of Ediz Hook, a peninsula that extends into the 
Strait of Juan de Fuca, encompassing approximately 8.73 square 
kilometers (km\2\) (3.37 square miles (mi\2\)), opening to the east 
(Figure 1).

[[Page 61551]]

[GRAPHIC] [TIFF OMITTED] TN07SE23.013

Detailed Description of the Specified Activity

    The Coast Guard proposes to conduct construction activities related 
to pier maintenance and bank stabilization to protect critical 
infrastructure from tidal and storm erosion using methods including 
impact and vibratory pile installation and vibratory pile extraction. 
Activity details for the work under this proposed IHA are provided in 
Table 1. Pile driving activities would be barge-based. Impact and 
vibratory driving activities would occur on the same days. Simultaneous 
use of multiple hammers would not occur, and is therefore not discussed 
further in this notice. In-water pile driving work is expected to take 
approximately 15 days to complete, and would occur during daylight 
hours only, at the lowest possible tide conditions.
    Pile removal will be by direct-pull or by vibratory extraction. 
Vibratory extraction of timber piles may occur for up to 8 hours per 
day, at an estimated rate of 16 piles per day (estimated 30 minutes 
required to extract each timber or steel pile). Vibratory extraction of 
timber piles is expected to take no more than seven days. Vibratory 
extraction of steel piles is expected to take approximately two hours 
over the course of two days.
    Pile installation will be by vibratory driving until refusal is 
encountered, with the potential for impact proofing of each installed 
pile depending on substrate conditions. Vibratory installation is 
expected to take approximately 30 minutes per pile, at an estimated 
average rate of approximately 10 piles per day. Impact proofing of 
installed steel piles could occur on the same day as vibratory 
installation, and would involve approximately 100 strikes per pile and 
a maximum of 5 piles per day.

                                                                Table 1--Pile Information
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                                                                                              Total    Piles per                                 Total
              Pile type                   Install or extract               Method             piles       day       Hours or strikes per day    days \1\
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12-inch (in) steel..................  Install..................  Vibratory................         37         10  5 hours....................          7
18-in steel.........................  Extract..................  Vibratory................          3          2  1 hour.....................          2
12-14-in timber.....................  Extract..................  Vibratory................         48         16  8 hours....................          6
12-in steel.........................  Install..................  Impact...................         37          5  100 strikes................          8
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\1\ Approximately 14 days of in-water pile driving would be required for this project. Some activities would occur on the same day (i.e., vibratory and
  impact installation of steel piles, vibratory extraction of steel and timber piles).

    Other components of this project include both in-water and upland 
activities, which are not expected to result in take of marine mammals. 
Pile repair (i.e., power washing, jacketing, and anti-fouling coating), 
deck repair and replacement, utility installation, and shoreline 
stabilization (i.e., removal and replacement of riprap shoreline) are 
therefore not discussed further in this document.
    Proposed mitigation, monitoring, and reporting measures are 
described in detail later in this document (please see

[[Page 61552]]

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; 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 this activity, and summarizes information 
related to the population or stock, including regulatory status under 
the MMPA and Endangered Species Act (ESA) and potential biological 
removal (PBR), where known. 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 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' U.S. Pacific SARs. All values presented in Table 2 are the most 
recent available at the time of publication (including from the final 
2022 SARs) and are available online at: www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments.

                                            Table 2--Species Likely Impacted by the Specified Activities \1\
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                                                                                         ESA/ MMPA status;   Stock  abundance (CV,
             Common name                  Scientific name               Stock             strategic (Y/N)      Nmin, most recent       PBR     Annual M/
                                                                                                \2\         abundance  survey) \3\               SI \4\
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                                            Order Artiodactyla--Infraorder Cetacea--Mysticeti (baleen whales)
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Family Balaenopteridae (rorquals):
Humpback whale......................  Megaptera novaeangliae.  Hawai[revaps]i.........  -, -, N             11,278 (0.56, 7,265,          127      27.09
                                                                                                             2020).
                                                               Mainland Mexico-CA/OR/   T, D, Y             3,477 (0.101, 3,185,           43         22
                                                                WA.                                          2022).
                                                               Central America/         E, D, Y             1,496 (0.171, 1,284,          5.2       14.9
                                                                Southern Mexico-CA/OR/                       2022).
                                                                WA.
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                                                  Odontoceti (toothed whales, dolphins, and porpoises)
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Family Delphinidae:
Killer whale........................  Orcinus orca...........  Eastern North Pacific    E, D, Y             74 (N/A, 74, 2021)....       0.13      >=0.4
                                                                Southern Resident.
                                                               West Coast Transient...  -, -, N             349 (N/A, 349, 2018)..        3.5        0.4
Family Phocoenidae (porpoises):
Harbor porpoise.....................  Phocoena phocoena......  Washington Inland        -, -, N             11,233 (0.37, 8,308,           66      >=7.2
                                                                Waters.                                      2015).
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                                                               Order Carnivora--Pinnipedia
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Family Otariidae (eared seals and
 sea lions):
Steller sea lion....................  Eumetopias jubatus.....  Eastern................  -, -, N             43,201 (N/A, 43,201,        2,592        112
                                                                                                             2017).
California sea lion.................  Zalophus californianus.  U.S....................  -, -, N             257,606 (N/A, 233,515,     14,011       >321
                                                                                                             2014).
Family Phocidae (earless seals):
Harbor seal.........................  Phoca vitulina.........  Washington Northern      -, -, N             UNK (UNK, UNK, 1999)..        UND        9.8
                                                                Inland Waters.
Northern elephant seal..............  Mirounga angustirostris  CA Breeding............  -, -, N             187,386 (N/A, 85,369,       5,122       13.7
                                                                                                             2013).
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\1\ 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/; Committee on Taxonomy (2022)).
\2\ Endangered Species Act (ESA) status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-) indicates that the species is not listed
  under the ESA or designated as depleted under the MMPA. Under the MMPA, a strategic stock is one for which the level of direct human-caused mortality
  exceeds PBR or which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed
  under the ESA is automatically designated under the MMPA as depleted and as a strategic stock.
\3\ NMFS marine mammal stock assessment reports online at: www.nmfs.noaa.gov/pr/sars/. CV is coefficient of variation; Nmin is the minimum estimate of
  stock abundance. In some cases, CV is not applicable.
\4\ 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, vessel 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.

    As indicated above, all 7 species (with 6 managed stocks) in Table 
2 temporally and spatially co-occur with the activity to the degree 
that take is reasonably likely to occur. While gray whales 
(Eschrichtius robustus) and minke whales (Balaenoptera acutorostrata) 
have been documented in the project 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

[[Page 61553]]

explanation provided here. The project area (Port Angeles Harbor) is a 
relatively small embayment along the coast of the Strait of Juan de 
Fuca. While gray whales occasionally visit this area during their 
seasonal migrations, and approximately a dozen identified individuals 
are known to regularly return to Puget Sound (Calambokidis et al., 
2018). However, it would be unusual for one to enter the enclosed 
harbor area. Minke whales have been reported in Washington inland 
waters year-round, although few are reported in the winter (i.e., 
during the anticipated in-water work window for this project; 
Calambokidis and Baird 1994). Given the limited timeframe of the 
project and the low likelihood of a gray or minke whale approaching the 
enclosed and highly-trafficked Port Angeles Harbor, no takes of these 
species are proposed for authorization. Additionally, the Coast Guard 
proposes to shut down pile driving work when any large whale for which 
take is not authorized approaches the Level B harassment isopleth.

Humpback Whale

    Humpback whales are found in coastal waters of Washington as they 
migrate from feeding grounds in Alaska to California to winter breeding 
grounds in Mexico. Humpbacks used to be considered rare visitors to 
Puget Sound. In 1976 and 1978, two sightings were reported in Puget 
Sound and one sighting was reported in 1986 (Osborne et al., 1988; 
Calambokidis and Steiger 1990; Calambokidis and Baird 1994). Humpback 
whale occurrence in Puget Sound has been steadily increasing since 
2000, with some individuals remaining in the area through the winter 
(Calambokidis et al., 2018). Between 1988 and 2015, 154 unique 
individual humpback whales were identified within Washington-British 
Columbia inside waters, with 500 or more sighting reports of humpback 
whales in the Salish Sea in both 2014 and 2015 (Calambokidis et al. 
2017).
    The 2022 Alaska and Pacific SARs described a revised stock 
structure for humpback whales which modifies the previous stocks 
designated under the MMPA to align more closely with the ESA-designated 
DPSs (Caretta et al., 2023; Young et al., 2023). Specifically, the 
three previous North Pacific humpback whale stocks (Central and Western 
North Pacific stocks and a CA/OR/WA stock) were replaced by five 
stocks, largely corresponding with the ESA-designated DPSs. These 
include Western North Pacific and Hawai[revaps]i stocks and a Central 
America/Southern Mexico-CA/OR/WA stock (which corresponds with the 
Central America DPS). The remaining two stocks, corresponding with the 
Mexico DPS, are the Mainland Mexico-CA/OR/WA and Mexico-North Pacific 
stocks (Caretta et al., 2023; Young et al., 2023). The former stock is 
expected to occur along the west coast from California to southern 
British Columbia, while the latter stock may occur across the Pacific, 
from northern British Columbia through the Gulf of Alaska and Aleutian 
Islands/Bering Sea region to Russia. The stocks that may occur in the 
proposed project area are: Hawai[revaps]i, Mainland Mexico-CA/OR/WA, 
and Central America/Southern Mexico-CA/OR/WA.
    The Hawai[revaps]i stock consists of one demographically 
independent population (DIP)--Hawai[revaps]i--Southeast Alaska/Northern 
British Columbia DIP and one unit--Hawai[revaps]i--North Pacific unit, 
which may or may not be composed of multiple DIPs (Wade et al., 2021). 
The DIP and unit are managed as a single stock at this time, due to the 
lack of data available to separately assess them and lack of compelling 
conservation benefit to managing them separately (NMFS, 2023; NMFS, 
2019; NMFS, 2022). The DIP is delineated based on two strong lines of 
evidence: genetics and movement data (Wade et al., 2021). Whales in the 
Hawai[revaps]i--Southeast Alaska/Northern British Columbia DIP winter 
off Hawai[revaps]i and largely summer in Southeast Alaska and Northern 
British Columbia (Wade et al., 2021). The group of whales that migrate 
from Russia, western Alaska (Bering Sea and Aleutian Islands), and 
central Alaska (Gulf of Alaska excluding Southeast Alaska) to 
Hawai[revaps]i have been delineated as the Hawai[revaps]i-North Pacific 
unit (Wade et al., 2021). There are a small number of whales that 
migrate between Hawai[revaps]i and southern British Columbia/
Washington, but current data and analyses do not provide a clear 
understanding of which unit these whales belong to (Wade et al., 2021) 
(Caretta et al., 2023; Young et al., 2023).
    The Mainland Mexico-CA/OR/WA stock consists of one DIP. Delineation 
of the Mainland Mexico-California/Oregon/Washington DIP is based on two 
strong lines of evidence indicating demographic independence: genetics 
and movement data (Martien et al. 2021). Whales in this stock winter 
off the mainland Mexico states of Nayarit and Jalisco, with some 
animals seen as far south as Colima and Michoac[aacute]n. Summer 
destinations for whales in the Mainland Mexico DPS include U.S. West 
Coast waters of California, Oregon, Washington (including the Salish 
Sea, Martien et al. 2021), Southern British Columbia, Alaska, and the 
Bering Sea.
    The Central America/Southern Mexico-CA/OR/WA stock consists of one 
DIP, for which delineation is based on two strong lines of evidence 
indicating demographic independence: genetics and movement data (Taylor 
et al. 2021). Whales in this stock winter off the Pacific coast of 
Nicaragua, Honduras, El Salvador, Guatemala, Panama, Costa Rica and 
likely southern coastal Mexico (Taylor et al. 2021). Summer 
destinations for whales in this DIP include the U.S. West Coast waters 
of California, Oregon, and Washington (including the Salish Sea, 
Calambokidis et al. 2017).
    According to Wade et al. (2021), the probability that humpback 
whales encountered in Washington and Southern British Columbia waters 
belong to various DPSs are as follows: Hawai'i DPS, 69 percent; Mexico 
DPS, 25 percent; and Central America DPS, 6 percent. We therefore 
assume that the numbers of humpback whales taken incidental to the 
Coast Guard's proposed activities would fall under the same relative 
proportions. Critical habitat for Mexico and Central America DPS 
humpback whales has been established on the outer coast of Washington 
(86 FR 21082; April 21, 2021) but does not overlap the project area.
    Humpback whales are most often spotted in the Port Angeles area 
from May to June and from September to October, during their migration 
(Patry, 2022). During a 2016-2017 U.S. Navy Department of the Navy 
(U.S. Navy) Pier and Support Facilities for Transit Protection System 
(TPS) project in Port Angeles (U.S. Navy TPS Port Angeles Project), 
three ``possible'' whale sightings were recorded; however, species and 
confirmation could not be obtained (Northwest Environmental Consulting, 
LLC., 2018).

Killer Whale

    There are three distinct ecotypes, or forms, of killer whales 
recognized in the north Pacific Ocean: resident, transient, and 
offshore. The three ecotypes differ morphologically, ecologically, 
behaviorally, and genetically. Resident killer whales exclusively prey 
upon fish, with a clear preference for salmon (Ford and Ellis 2006; 
Hanson et al., 2010; Ford et al., 2016), while transient killer whales 
exclusively prey upon marine mammals (Caretta et al., 2023). Less is 
known about offshore killer whales, but they are believed to consume 
primarily fish, including several species of shark (Dahlheim et al., 
2008). Currently, there are eight killer whale stocks recognized in the 
U.S. Pacific Ocean (Carretta et al., 2023;

[[Page 61554]]

Young et al. 2023). Of those, individuals from the Southern Resident 
stock and West Coast Transient stocks could occur in the Port Angeles 
area and be taken incidental to the Coast Guard's proposed activities.
    The Southern Resident killer whale (SRKW) population is comprised 
of three pods, J, K, and L pods, which typically travel independently 
of each other. The stock occurs for part of the year in the inland 
waterways of the Salish Sea, including Puget Sound, the Strait of Juan 
de Fuca, and the southern Strait of Georgia mostly during the spring, 
summer, and fall. Their movement patterns appear related to the 
seasonal availability of prey, especially Chinook salmon (Oncorhynchus 
tshawytscha). They also move to coastal waters, primarily off 
Washington and British Columbia, and have been observed as far as 
central California and southeast Alaska (Caretta et al., 2023). During 
the fall, SRKW, especially J pod, expand their movements into Puget 
Sound (Hanson et al., 2021).
    The SRKW DPS was listed as endangered under the ESA in 2005 after a 
nearly 20 percent decline in abundance between 1996 and 2001 (70 FR 
69903; November 18, 2005). As compared to stable or growing 
populations, the DPS reflects lower fecundity and has demonstrated 
little to no growth in recent decades, and in fact has declined further 
since the date of listing (NMFS 2022b). The population abundance listed 
in the final 2022 SARs is 74 individuals, from the July 1, 2021 annual 
census conducted by the Center for Whale Research (Carretta et al., 
2023).
    The West Coast Transient stock of killer whales occurs from 
California through southeast Alaska (Young et al. 2023). The seasonal 
movements of transients are largely unpredictable, although there is a 
tendency to investigate harbor seal haulouts off Vancouver Island more 
frequently during the pupping season in August and September (Baird 
1994; Ford 2014). Transient killer whales have been observed in the 
Strait of Juan de Fuca in all months and sightings in the Salish Sea 
have increased since 2000 (Houghton et al., 2015).
    A previous construction monitoring project in Port Angeles Harbor 
documented no sightings of either SRKW or transient killer whales over 
38 days of monitoring, though two ``possible'' whale sightings were 
recorded (Northwest Environmental Consulting, LLC., 2018).

Harbor Porpoise

    In the eastern North Pacific Ocean, harbor porpoise are found in 
coastal and inland waters from Point Barrow, along the Alaskan coast, 
and down the west coast of North America to Point Conception, 
California (Gaskin 1984). Harbor porpoise are known to occur year-round 
in the inland trans-boundary waters of Washington and British Columbia, 
Canada (Osborne et al., 1988), and along the Oregon/Washington coast 
(Barlow 1988, Barlow et al., 1988, Green et al., 1992). There was a 
significant decline in harbor porpoise sightings within southern Puget 
Sound between the 1940s and 1990s but sightings have increased 
seasonally in the last 10 years (Carretta et al., 2023). Annual winter 
aerial surveys conducted by the Washington Department of Fish and 
Wildlife from 1995 to 2015 revealed an increasing trend in harbor 
porpoise in Washington inland waters, including the return of harbor 
porpoise to Puget Sound. The data suggest that harbor porpoise were 
already present in Juan de Fuca, Georgia Straits, and the San Juan 
Islands from the mid-1990s to mid-2000s, and then expanded into Puget 
Sound and Hood Canal from the mid-2000s to 2015, areas they had used 
historically but abandoned. Changes in fishery-related entanglement was 
suspected as the cause of their previous decline and more recent 
recovery, including a return to Puget Sound (Evenson et al., 2016). 
Seasonal surveys conducted in spring, summer, and fall 2013-2015 in 
Puget Sound and Hood Canal documented substantial numbers of harbor 
porpoise in Puget Sound. Observed porpoise numbers were twice as high 
in spring as in fall or summer, indicating a seasonal shift in 
distribution of harbor porpoise (Smultea 2015). The reasons for the 
seasonal shift and for the increase in sightings is unknown. Monitoring 
from a previous construction project in Port Angeles Harbor sighted six 
harbor porpoise over 38 days of monitoring (Northwest Environmental 
Consulting, LLC., 2018).

Steller Sea Lion

    Steller sea lions range along the North Pacific Rim from northern 
Japan to California (Loughlin et al., 1984). There are two separate 
stocks of Steller sea lions, the eastern U.S. stock, which occurs east 
of Cape Suckling, Alaska (144[deg] W), and the western U.S. stock, 
which occurs west of that point. Only the western stock of Steller sea 
lions, which is designated as the western DPS of Steller sea lions, is 
listed as endangered under the ESA (78 FR 66139; November 4, 2013). 
Unlike the western U.S. stock of Steller sea lions, there has been a 
sustained and robust increase in abundance of the eastern U.S. stock 
throughout its breeding range. The eastern stock of Steller sea lions 
has historically bred on rookeries located in Southeast Alaska, British 
Columbia, Oregon, and California. However, within the last several 
years a new rookery has become established on the outer Washington 
coast (at the Carroll Island and Sea Lion Rock complex), with more than 
100 pups born there in 2015 (Young et al., 2023).
    Steller sea lions use haulout locations in Puget Sound, and may 
occur at the same haulouts as California sea lions. The closest known 
haulout for Steller sea lions is approximately 15 mi (24.14 km) away 
from Port Angeles on the Canadian side of the Strait of Juan de Fuca 
(Jefferies et al. 2000, Edgell & Demarchi, 2012). Thus, although 
Steller sea lions may occasionally use the waters around Port Angeles 
to pursue local prey, their presence in Port Angeles harbor is likely 
limited due to the long transit involved in returning to their haulout 
site. Observers reported sightings of two Steller sea lions during pile 
driving activities associated with the Navy TPS Port Angeles Project in 
2016-2017 over 38 days of monitoring (Northwest Environmental 
Consulting, LLC., 2018).

California Sea Lion

    The California sea lion is the most frequently sighted pinniped 
found in Washington waters and uses haulout sites along the outer 
coast, Strait of Juan de Fuca, and in Puget Sound. Haulout sites are 
located on jetties, offshore rocks and islands, log booms, marina 
docks, and navigation buoys. This species also may be frequently seen 
resting in the water, rafted together in groups in Puget Sound. Only 
male California sea lions migrate into Pacific Northwest waters, with 
females remaining in waters near their breeding rookeries off the coast 
of California and Mexico. The California sea lion was considered rare 
in Washington waters prior to the 1950s, but prevalence has increased 
regularly since the passing of the MMPA. In the 1990s, Jeffries et al. 
(2000) documented peak numbers of 3,000 to 5,000 animals moving into 
the Salish Sea during the fall and remaining until late spring, when 
most returned to breeding rookeries in California and Mexico (Jeffries 
et al., 2000). More recent research has indicated that California sea 
lions continue to use the Salish Sea and Strait of Juan de Fuca 
regularly, with a mean estimated abundance of 2,489 (95% confidence

[[Page 61555]]

interval of 253--24,491) animals in these regions in the spring 
(Jefferson et al. 2023), and up to 836 individuals counted during the 
month of October at a nearby Canadian haulout (Edgell & Demarchi, 
2012). Additionally, satellite tagging data has tracked individual 
animals tagged at U.S. Navy facilities in southern Puget Sound passing 
close to remaining near Port Angeles Harbor for multiple days in 2015 
and 2016 (DeLong et al. 2017).
    California sea lions are often observed in the area of potential 
effects and are known to be comfortable and seemingly curious around 
human activities. They regularly haul out on structures such as buoys, 
floats, and docks. In Port Angeles Harbor there are no known California 
sea lion haulouts; the nearest known haulout is across the Strait of 
Juan de Fuca at Race Rocks in British Columbia, Canada, approximately 
19.5 km (12.1 mi) from the proposed project site (Edgell & Demarchi, 
2012). The nearest known haulout in U.S. waters is at Sombio Point, 
which is approximately 45 mi (72.4 km) from Port Angeles (Jefferies et 
al. 2000). As a result, their use of Port Angeles Harbor is likely to 
be limited. However, occasional foraging forays may bring them into the 
area as surveys at Navy facilities indicate a few individuals are 
present in the area through mid-June to July with some arrivals in 
August (U.S. Navy 2019). Observers reported sightings of 21 California 
sea lions during pile driving activities associated with the Navy TPS 
Port Angeles Project in 2016 and 2017 (Northwest Environmental 
Consulting, LLC 2018).

Harbor Seal

    Harbor seals inhabit coastal and estuarine waters off Baja 
California, north along the western coasts of the continental United 
States, British Columbia, and Southeast Alaska, west through the Gulf 
of Alaska and Aleutian Islands, and in the Bering Sea north to Cape 
Newenham and the Pribilof Islands (Carretta et al., 2023). They haul 
out on rocks, reefs, beaches, and drifting glacial ice and feed in 
marine, estuarine, and occasionally fresh waters. Harbor seals 
generally are non-migratory, with local movements associated with such 
factors as tides, weather, season, food availability, and reproduction 
(Scheffer and Slipp 1944; Fisher 1952; Bigg 1969, 1981). Within U.S. 
west coast waters, five stocks of harbor seals are recognized: (1) 
Southern Puget Sound (south of the Tacoma Narrows Bridge); (2) 
Washington Northern Inland Waters (including Puget Sound north of the 
Tacoma Narrows Bridge, the San Juan Islands, and the Strait of Juan de 
Fuca); (3) Hood Canal; (4) Oregon/Washington Coast; and (5) California. 
Harbor seals in the project areas would be from the Washington Northern 
Inland Waters stock.
    Harbor seals are the only pinniped species that occurs year-round 
and breeds in Washington waters (Jeffries et al., 2000). Pupping 
seasons vary by geographic region, with pups born in coastal estuaries 
(Columbia River, Willapa Bay, and Grays Harbor) from mid-April through 
June; Olympic Peninsula coast from May through July; San Juan Islands 
and eastern bays of Puget Sound from June through August; southern 
Puget Sound from mid-July through September; and Hood Canal from August 
through January (Jeffries et al., 2000). Harbor seals have haulouts 
throughout Puget Sound and the Strait of Juan de Fuca and some of their 
haulouts are in close proximity to Air Station Port Angeles. They haul 
out year-round on log booms and beach areas. Known haulout locations 
are indicated in Figure 2 of the IHA Application. One is approximately 
11,572 ft (3,527 m) west and the other is approximately 7,877 ft (2,401 
m) south of the project area. Haulout locations may change, and harbor 
seals may also use other undocumented haulout sites within or around 
Port Angeles harbor.
    Harbor seals are commonly sighted in and are expected to forage 
within Port Angeles Harbor year round. Observers reported sightings of 
1,009 harbor seals during 38 days of pile driving associated with the 
Navy TPS Port Angeles Project in 2016-2017 (Northwest Environmental 
Consulting, LLC., 2018).

Northern Elephant Seal

    Northern elephant seals breed and give birth in California (U.S.) 
and Baja California (Mexico), primarily on offshore islands (Stewart et 
al. 1994), from December to March. Males migrate to the Gulf of Alaska 
and western Aleutian Islands along the continental shelf to feed on 
benthic prey, while females migrate to pelagic areas in the Gulf of 
Alaska and the central North Pacific Ocean to feed on pelagic prey (Le 
Boeuf et al., 2000). Adults return to land between March and August to 
molt, with males returning later than females. Adults return to their 
feeding areas again between their spring/summer molting and their 
winter breeding seasons (Carretta et al., 2023).
    Seasonal abundance estimates for northern elephant seals in the 
inland waters of Washington (Strait of Juan de Fuca) range from 3 
animals in winter to 12 animals in fall (U.S. Navy 2019). Haulouts for 
Northern elephant seals are located on offshore islands or islands and 
spits in the Strait of Juan de Fuca (Jefferies et al. 2000). Observers 
reported no sightings of northern elephant seals during pile driving 
activities associated with the Navy TPS Port Angeles Project in 2016 
through 2017 (Northwest Environmental Consulting, LLC., 2018).

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.). Note that no direct measurements of 
hearing ability have been successfully completed for mysticetes (i.e., 
low-frequency cetaceans). Subsequently, NMFS (2018) described 
generalized hearing ranges for these marine mammal hearing groups. 
Generalized hearing ranges were chosen based on the approximately 65 
decibel (dB) threshold from the normalized composite audiograms, with 
the exception for lower limits for low-frequency cetaceans where the 
lower bound was deemed to be biologically implausible and the lower 
bound from Southall et al. (2007) retained. Marine mammal hearing 
groups and their associated hearing ranges are provided in Table 3.

[[Page 61556]]



                  Table 3--Marine Mammal Hearing Groups
                              [NMFS, 2018]
------------------------------------------------------------------------
             Hearing group                 Generalized hearing range *
------------------------------------------------------------------------
Low-frequency (LF) cetaceans (baleen    7 Hz to 35 kHz.
 whales).
Mid-frequency (MF) cetaceans            150 Hz to 160 kHz.
 (dolphins, toothed whales, beaked
 whales, bottlenose whales).
High-frequency (HF) cetaceans (true     275 Hz to 160 kHz.
 porpoises, Kogia, river dolphins,
 Cephalorhynchid, Lagenorhynchus
 cruciger & L. australis).
Phocid pinnipeds (PW) (underwater)      50 Hz to 86 kHz.
 (true seals).
Otariid pinnipeds (OW) (underwater)     60 Hz to 39 kHz.
 (sea lions and fur seals).
------------------------------------------------------------------------
* Represents the generalized hearing range for the entire group as a
  composite (i.e., all species within the group), where individual
  species' hearing ranges are typically not as broad. Generalized
  hearing range chosen based on ~65 dB threshold from normalized
  composite audiogram, with the exception for lower limits for LF
  cetaceans (Southall et al. 2007) and PW pinniped (approximation).

    The pinniped functional hearing group was modified from Southall et 
al. (2007) on the basis of data indicating that phocid species have 
consistently demonstrated an extended frequency range of hearing 
compared to otariids, especially in the higher frequency range 
(Hemil[auml] et al., 2006; Kastelein et al., 2009; Reichmuth et al., 
2013). This division between phocid and otariid pinnipeds is now 
reflected in the updated hearing groups proposed in Southall et al. 
(2019).
    For more detail concerning these groups and associated frequency 
ranges, please see NMFS (2018) 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.
    Acoustic effects on marine mammals during the specified activity 
are expected to potentially occur from impact and vibratory pile 
installation and removal. The effects of underwater noise from Coast 
Guard's proposed activities have the potential to result in Level B 
harassment of marine mammals in Port Angeles Harbor.

Background on Sound

    This section contains a brief technical background on sound, on the 
characteristics of certain sound types, and on metrics used relevant to 
the specified activity and to a discussion of the potential effects of 
the specified activity on marine mammals found later in this document. 
For general information on sound and its interaction with the marine 
environment, please see, Erbe and Thomas (2022); Au and Hastings 
(2008); Richardson et al. (1995); Urick (1983); as well as the 
Discovery of Sound in the Sea (DOSITS) website at https://dosits.org/.
    Sound is a vibration that travels as an acoustic wave through a 
medium such as a gas, liquid or solid. Sound waves alternately compress 
and decompress the medium as the wave travels. In water, sound waves 
radiate in a manner similar to ripples on the surface of a pond and may 
be either directed in a beam (narrow beam or directional sources) or 
sound may radiate in all directions (omnidirectional sources), as is 
the case for sound produced by the construction activities considered 
here. The compressions and decompressions associated with sound waves 
are detected as changes in pressure by marine mammals and human-made 
sound receptors such as hydrophones.
    Sound travels more efficiently in water than almost any other form 
of energy, making the use of sound as a primary sensory modality ideal 
for inhabitants of the aquatic environment. In seawater, sound travels 
at roughly 1,500 meters per second (m/s). In air, sound waves travel 
much more slowly, at about 340 m/s. However, the speed of sound in 
water can vary by a small amount based on characteristics of the 
transmission medium such as temperature and salinity.
    The basic characteristics of a sound wave are frequency, 
wavelength, velocity, and amplitude. Frequency is the number of 
pressure waves that pass by a reference point per unit of time and is 
measured in hertz (Hz) or cycles per second. Wavelength is the distance 
between two peaks or corresponding points of a sound wave (length of 
one cycle). Higher frequency sounds have shorter wavelengths than lower 
frequency sounds, and typically attenuate (decrease) more rapidly with 
distance, except in certain cases in shallower water. The amplitude of 
a sound pressure wave is related to the subjective ``loudness'' of a 
sound and is typically expressed in dB, which are a relative unit of 
measurement that is used to express the ratio of one value of a power 
or pressure to another. A sound pressure level (SPL) in dB is described 
as the ratio between a measured pressure and a reference pressure, and 
is a logarithmic unit that accounts for large variations in amplitude; 
therefore, a relatively small change in dB corresponds to large changes 
in sound pressure. For example, a 10-dB increase is a ten-fold increase 
in acoustic power. A 20-dB increase is then a 100-fold increase in 
power and a 30-dB increase is a 1,000-fold increase in power. However, 
a 10-fold increase in acoustic power does not mean that the sound is 
perceived as being 10 times louder. The dB is a relative unit comparing 
two pressures; therefore, a reference pressure must always be 
indicated. For underwater sound, this is 1 microPascal ([mu]Pa). For 
in-air sound, the reference pressure is 20 microPascal ([mu]Pa). The 
amplitude of a sound can be presented in various ways; however, NMFS 
typically considers three metrics: sound exposure level (SEL), root-
mean-square (RMS) SPL, and peak SPL (defined below). The source level 
represents the SPL referenced at a standard distance from the source 
(Richardson et al., 1995; American National Standards Institute (ANSI), 
2013)(typically 1 m) (Richardson et al., 1995; American National 
Standards Institute (ANSI), 2013), while the received level is the SPL 
at the receiver's position. For pile

[[Page 61557]]

driving activities, the SPL is typically referenced at 10 m.
    SEL (represented as dB referenced to 1 micropascal squared second 
(re 1 [mu]Pa\2\-s)) represents the total energy in a stated frequency 
band over a stated time interval or event, and considers both intensity 
and duration of exposure. The per-pulse SEL (e.g., single strike or 
single shot SEL) is calculated over the time window containing the 
entire pulse (i.e., 100 percent of the acoustic energy). SEL can also 
be a cumulative metric; it can be accumulated over a single pulse (for 
pile driving this is the same as single-strike SEL, above; 
SELss), or calculated over periods containing multiple 
pulses (SELcum). Cumulative SEL (SELcum) 
represents the total energy accumulated by a receiver over a defined 
time window or during an event. The SEL metric is useful because it 
allows sound exposures of different durations to be related to one 
another in terms of total acoustic energy. The duration of a sound 
event and the number of pulses, however, should be specified as there 
is no accepted standard duration over which the summation of energy is 
measured.
    RMS SPL is equal to ten times the logarithm (base 10) of the ratio 
of the mean-square sound pressure to the specified reference value, and 
given in units of dB (International Organization for Standardization 
(ISO), 2017). RMS is calculated by squaring all of the sound 
amplitudes, averaging the squares, and then taking the square root of 
the average (Urick, 1983). RMS accounts for both positive and negative 
values; squaring the pressures makes all values positive so that they 
may be accounted for in the summation of pressure levels (Hastings and 
Popper, 2005). This measurement is often used in the context of 
discussing behavioral effects, in part because behavioral effects, 
which often result from auditory cues, may be better expressed through 
averaged units than by peak SPL. For impulsive sounds, RMS is 
calculated by the portion of the waveform containing 90 percent of the 
sound energy from the impulsive event (Madsen, 2005).
    Peak SPL (also referred to as zero-to-peak sound pressure or 0-pk) 
is the maximum instantaneous sound pressure measurable in the water, 
which can arise from a positive or negative sound pressure, during a 
specified time, for a specific frequency range at a specified distance 
from the source, and is represented in the same units as the RMS sound 
pressure (ISO, 2017). Along with SEL, this metric is used in evaluating 
the potential for permanent threshold shift (PTS) and temporary 
threshold shift (TTS) associated with impulsive sound sources.
    Sounds may be either impulsive or non-impulsive (defined below). 
The distinction between these two sound types is important because they 
have differing potential to cause physical effects, particularly with 
regard to noise-induced hearing loss (e.g., Ward, 1997 in Southall et 
al., 2007). Please see NMFS (2018) and Southall et al. (2007; 2019) for 
an in-depth discussion of these concepts.
    Impulsive sound sources (e.g., explosions, gunshots, sonic booms, 
seismic airgun shots, impact pile driving) produce signals that are 
brief (typically considered to be less than one second), broadband, 
atonal transients (ANSI, 1986; NIOSH, 1998; ANSI, 2005) and occur 
either as isolated events or are repeated in some succession. Impulsive 
sounds are all characterized by a relatively rapid rise from ambient 
pressure to a maximal pressure value followed by a rapid decay period 
that may include a period of diminishing, oscillating maximal and 
minimal pressures, and generally have an increased capacity to induce 
physical injury as compared with sounds that lack these features. 
Impulsive sounds are intermittent in nature. The duration of such 
sounds, as received at a distance, can be greatly extended in a highly 
reverberant environment.
    Non-impulsive sounds can be tonal, narrowband, or broadband, brief 
or prolonged, and may be either continuous or non-continuous (ANSI, 
1995; NIOSH, 1998). Some of these non-impulsive sounds can be transient 
signals of short duration but without the essential properties of 
impulses (e.g., rapid rise time). Examples of non-impulsive sounds 
include those produced by vessels, aircraft, machinery operations such 
as drilling (including DTH systems) or dredging, vibratory pile 
driving, and active sonar systems.
    Even in the absence of sound from the specified activity, the 
underwater environment is characterized by sounds from both natural and 
anthropogenic sound sources. Ambient sound is defined as a composite of 
naturally-occurring (i.e., non-anthropogenic) sound from many sources 
both near and far (ANSI, 1995). Background sound is similar, but 
includes all sounds, including anthropogenic sounds, minus the sound 
produced by the proposed (NMFS, 2012; 2016). The sound level of a 
region is defined by the total acoustical energy being generated by 
known and unknown sources. These sources may include physical (e.g., 
wind and waves, earthquakes, ice, atmospheric sound), biological (e.g., 
sounds produced by marine mammals, fish, and invertebrates), and 
anthropogenic (e.g., vessels, dredging, construction) sound. A number 
of sources contribute to background and ambient sound, including wind 
and waves, which are a main source of naturally occurring ambient sound 
for frequencies between 200 Hz and 50 kilohertz (kHz) (Mitson, 1995). 
In general, background and ambient sound levels tend to increase with 
increasing wind speed and wave height. Precipitation can become an 
important component of total sound at frequencies above 500 Hz, and 
possibly down to 100 Hz during quiet times. Marine mammals can 
contribute significantly to background and ambient sound levels, as can 
some fish and snapping shrimp. The frequency band for biological 
contributions is from approximately 12 Hz to over 100 kHz. Sources of 
background sound related to human activity include transportation 
(surface vessels), dredging and construction, oil and gas drilling and 
production, geophysical surveys, sonar, and explosions. Vessel noise 
typically dominates the total background sound for frequencies between 
20 and 300 Hz. In general, the frequencies of many anthropogenic 
sounds, particularly those produced by construction activities, are 
below 1 kHz (Richardson et al., 1995). When sounds at frequencies 
greater than 1 kHz are produced, they generally attenuate relatively 
rapidly (Richardson et al., 1995), particularly above 20 kHz due to 
propagation losses and absorption (Urick, 1983).
    Transmission loss (TL) defines the degree to which underwater sound 
has spread in space and lost energy after having moved through the 
environment and reached a receiver. It is defined by the ISO as the 
reduction in a specified level between two specified points that are 
within an underwater acoustic field (ISO, 2017). Careful consideration 
of transmission loss and appropriate propagation modeling is a crucial 
step in determining the impacts of underwater sound, as it helps to 
define the ranges (isopleths) to which impacts are expected and depends 
significantly on local environmental parameters such as seabed type, 
water depth (bathymetry), and the local speed of sound. Geometric 
spreading laws are powerful tools which provide a simple means of 
estimating TL, based on the shape of the sound wave front in the water 
column. For a sound source that is equally loud in all directions and 
in deep water, the sound field takes the form of a sphere, as the sound 
extends

[[Page 61558]]

in every direction uniformly. In this case, the intensity of the sound 
is spread across the surface of the sphere, and thus we can relate 
intensity loss to the square of the range (as area = 4*pi*r\2\). When 
expressed logarithmically in dB as TL, we find that TL = 
20*Log10(range), this situation is known as spherical 
spreading. In shallow water, the sea surface and seafloor will bound 
the shape of the sound, leading to a more cylindrical shape, as the top 
and bottom of the sphere is truncated by the largely reflective 
boundaries. This situation is termed cylindrical spreading, and is 
given by TL = 10*Log10(range) (Urick, 1983). An intermediate 
scenario may be defined by the equation TL = 
15*Log10(range), and is referred to as practical spreading. 
Though these geometric spreading laws do not capture many often 
important details (scattering, absorption, etc.), they offer a 
reasonable and simple approximation of how sound decreases in intensity 
as it is transmitted. In the absence of measured data indicating the 
level of transmission loss at a given site for a specific activity, 
NMFS recommends practical spreading (i.e., 15*Log10(range)) 
to model acoustic propagation for construction activities in most 
nearshore environments.
    The sum of the various natural and anthropogenic sound sources at 
any given location and time depends not only on the source levels, but 
also on the propagation of sound through the environment. 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, background and ambient sound levels can be expected to vary 
widely over both coarse and fine spatial and temporal scales. Sound 
levels at a given frequency and location can vary by 10-20 dB from day 
to day (Richardson et al., 1995). The result is that, depending on the 
source type and its intensity, sound from the specified activity may be 
a negligible addition to the local environment or could form a 
distinctive signal that may affect marine mammals.
    USCG Air Station Port Angeles is located at the end of Ediz Hook, 
close to the entrance to Port Angeles Harbor, a relatively active and 
industrialized deepwater port with high levels of commercial and 
recreational vessel traffic. The Port of Port Angeles is the first 
full-service port available to ships entering the Strait of Juan de 
Fuca from the Pacific Ocean. It includes three deepwater marine 
terminals used for commercial shipping, as well as ferry terminals and 
recreational boat launches. Within the larger harbor area, pilot boat 
services, yacht clubs, and a naval facility also contribute to 
background noise. Although no ambient noise recordings are available 
from Port Angeles Harbor, it is reasonable to assume that background 
noise conditions are similar to other industrialized ports with daily 
operations of many sizes of vessels. Vessel traffic contributes 
significant amounts of noise to the marine environment throughout the 
Salish Sea, with most sound coming from commercial vessels (Burnham et 
al. 2021).

Description of Sound Sources for the Specified Activities

    In-water construction activities associated with the project would 
include impact pile installation and vibratory pile installation and 
removal. Impact hammers operate by repeatedly dropping and/or pushing a 
heavy piston onto a pile to drive the pile into the substrate. Sound 
generated by impact hammers is impulsive, 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 typically produce less sound (i.e., 
lower levels) than impact hammers. Peak 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; CALTRANS, 
2015; 2020). Sounds produced by vibratory hammers are non-impulsive; 
the rise time is slower, reducing the probability and severity of 
injury, and the sound energy is distributed over a greater amount of 
time (Nedwell and Edwards, 2002; Carlson et al., 2005).
    The likely or possible impacts of the Coast Guard's proposed 
activities 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, given 
that the closest pinniped haulout is approximately 2.5 mi or km from 
the site and located within the generalized area of a highly 
industrialized port area, the animals are likely to have habituated to 
the sight of construction personnel and activities. Therefore, visual 
and other non-acoustic stressors would be limited, and 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 or drilling is the primary means by which 
marine mammals may be harassed from the Coast Guard's specified 
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; 2019). Exposure to pile 
driving noise has the potential to result in auditory threshold shifts 
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 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 
(threshold shifts) followed by behavioral effects and potential impacts 
on habitat.
    NMFS defines a noise-induced threshold shift (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). The amount of 
threshold shift is customarily expressed in dB. A TS can be permanent 
or temporary. As described in NMFS, 2018, 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 animal uses sound within the frequency 
band of the signal; e.g., Kastelein et al. (2014)), and the

[[Page 61559]]

overlap between the animal and the source (e.g., spatial, temporal, and 
spectral). When considering auditory effects for the Coast Guard's 
proposed activities, vibratory pile driving is considered a non-
impulsive source, while impact pile driving is treated as an impulsive 
source.
    Permanent Threshold Shift (PTS)--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, 2018). 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 threshold 
shift approximates PTS onset (see Ward et al. (1958; 1959); Ward, 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)--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 marine mammal TTS measurements 
(see Southall et al. (2007; 2019)), a TTS of 6 dB is considered the 
minimum threshold shift clearly larger than any day-to-day or session-
to-session variation in a subject's normal hearing ability (Finneran et 
al., 2000; Schlundt et al., 2000; Finneran et al., 2002). As described 
in Finneran (2015), marine mammal studies have shown the amount of TTS 
increases with 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 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 
cetaceans, published data on the onset of TTS are limited to captive 
bottlenose dolphin (Tursiops truncatus), beluga whale (Delphinapterus 
leucas), harbor porpoise, and Yangtze finless porpoise (Neophocoena 
asiaeorientalis) (Southall et al., 2019). For pinnipeds in water, 
measurements of TTS are limited to harbor seals, elephant seals, 
bearded seals (Erignathus barbatus) and California sea lions (Kastak et 
al., 1999; 2007; Kastelein et al., 2019b; 2019c; Reichmuth et al., 
2019; Sills et al., 2020; Kastelein et al., 2021; 2022a; 2022b). TTS 
was not observed in spotted (Phoca largha) and ringed (Pusa hispida) 
seals exposed to single airgun impulse sounds at levels matching 
previous predictions of TTS onset (Reichmuth et al., 2016). These 
studies examine 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-exposure thresholds can be 
used to determine the amount of threshold shift 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 and harbor porpoises have a lower TTS onset than other measured 
pinniped or cetacean 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, cumulative 
SEL will overestimate the amount of TTS from intermittent exposures, 
such as sonars and impulsive sources. Nachtigall et al. (2018) describe 
measurements of hearing sensitivity of multiple odontocete species 
(bottlenose dolphin, harbor porpoise, beluga, 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). Data available on noise-induced 
hearing loss for mysticetes are currently lacking (NMFS, 2018). 
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, and there is no PTS data for cetaceans, but such 
relationships are assumed to be similar to those in humans and other 
terrestrial

[[Page 61560]]

mammals. PTS typically occurs at exposure levels at least several dB 
above that inducing mild TTS (e.g., a 40-dB threshold shift 
approximates PTS onset (Kryter et al., 1966; Miller, 1974), while a 6-
dB threshold shift 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 cumulative sound exposure level thresholds are 15 to 20 dB higher 
than TTS cumulative sound exposure level 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.
    Behavioral Harassment--Exposure to noise also has the potential to 
behaviorally disturb marine mammals to a level that rises to the 
definition of harassment under the MMPA. Generally speaking, NMFS 
considers a behavioral disturbance that rises to the level of 
harassment under the MMPA a non-minor response--in other words, not 
every response qualifies as behavioral disturbance, and for responses 
that do, those of a higher level, or accrued across a longer duration, 
have the potential to affect foraging, reproduction, or survival. 
Behavioral disturbance may include a variety of effects, including 
subtle changes in behavior (e.g., minor or brief avoidance of an area 
or changes in vocalizations), more conspicuous changes in similar 
behavioral activities, and more sustained and/or potentially severe 
reactions, such as displacement from or abandonment of high-quality 
habitat. Behavioral responses may include changing durations of 
surfacing and dives, changing direction and/or speed; reducing/
increasing vocal activities; changing/cessation of certain behavioral 
activities (such as socializing or feeding); eliciting a visible 
startle response or aggressive behavior (such as tail/fin slapping or 
jaw clapping); avoidance of areas where sound sources are located. 
Pinnipeds may increase their haul out 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., 2004; Southall et al., 
2007; Weilgart, 2007; Archer et al., 2010; Southall et al., 2019). 
Behavioral reactions can vary not only among individuals but also 
within an individual, depending on previous experience with a sound 
source, context, and numerous other factors (Ellison et al., 2012), and 
can vary depending on characteristics associated with the sound source 
(e.g., whether it is moving or stationary, number of sources, distance 
from the source). Please see Appendices B and C of Southall et al. 
(2007) and Gomez et al. (2016) for reviews 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 sources 
(typically seismic airguns or acoustic harassment devices) have been 
varied but often consist of avoidance behavior or other behavioral 
changes suggesting discomfort (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. If a marine mammal does react briefly to an underwater 
sound by changing its behavior or moving a small distance, the impacts 
of the change are unlikely to be significant to the individual, let 
alone the stock or population. However, if a sound source displaces 
marine mammals from an important feeding or breeding area for a 
prolonged period, impacts on individuals and populations could be 
significant (e.g., Lusseau and Bejder, 2007; Weilgart, 2007; NRC, 
2005). However, there are broad categories of potential response, which 
we describe in greater detail here, that include alteration of dive 
behavior, alteration of foraging behavior, effects to breathing, 
interference with or alteration of vocalization, avoidance, and flight.
    Changes in dive behavior can vary widely and may consist of 
increased or decreased dive times and surface intervals as well as 
changes in the rates of ascent and descent during a dive (e.g., Frankel 
and Clark, 2000; Costa et al., 2003; Ng and Leung, 2003; Nowacek et 
al., 2004; Goldbogen et al., 2013a, 2013b). Variations in dive behavior 
may reflect interruptions in biologically significant activities (e.g., 
foraging) or they may be of little biological significance. The impact 
of an alteration to dive behavior resulting from an acoustic exposure 
depends on what the animal is doing at the time of the exposure and the 
type and magnitude of the response.
    Disruption of feeding behavior can be difficult to correlate with 
anthropogenic sound exposure, so it is usually inferred by observed 
displacement from known foraging areas, the appearance of secondary 
indicators (e.g., bubble nets or sediment plumes), or changes in dive 
behavior. As for other types of behavioral response, the frequency, 
duration, and temporal pattern of signal presentation, as well as 
differences in species sensitivity, are likely contributing factors to 
differences in response in any given circumstance (e.g., Croll et al., 
2001; Nowacek et al., 2004; Madsen et al., 2006; Yazvenko et al., 
2007). A determination of whether foraging disruptions incur fitness 
consequences would require information on or estimates of the energetic 
requirements of the affected individuals and the relationship between 
prey availability, foraging effort and success, and the life history 
stage of the animal.
    Respiration rates vary naturally with different behaviors and 
alterations to breathing rate as a function of acoustic exposure can be 
expected to co-occur with other behavioral reactions, such as a flight 
response or an alteration in diving. However, respiration rates in and 
of themselves may be representative of annoyance or an acute stress 
response. Various studies have shown that respiration rates may either 
be

[[Page 61561]]

unaffected or could increase, depending on the species and signal 
characteristics, again highlighting the importance in understanding 
species differences in the tolerance of underwater noise when 
determining the potential for impacts resulting from anthropogenic 
sound exposure (e.g., Kastelein et al., 2001; 2005; 2006; Gailey et 
al., 2007).
    Marine mammals vocalize for different purposes and across multiple 
modes, such as whistling, echolocation click production, calling, and 
singing. Changes in vocalization behavior in response to anthropogenic 
noise can occur for any of these modes and may result from a need to 
compete with an increase in background noise or may reflect increased 
vigilance or a startle response. For example, in the presence of 
potentially masking signals, humpback whales and killer whales have 
been observed to increase the length of their songs (Miller et al., 
2000; Fristrup et al., 2003) or vocalizations (Foote et al., 2004), 
respectively, while North Atlantic right whales (Eubalaena glacialis) 
have been observed to shift the frequency content of their calls upward 
while reducing the rate of calling in areas of increased anthropogenic 
noise (Parks et al., 2007). In some cases, animals may cease sound 
production during production of aversive signals (Bowles et al., 1994).
    Avoidance is the displacement of an individual from an area or 
migration path as a result of the presence of a sound or other 
stressors, and is one of the most obvious manifestations of disturbance 
in marine mammals (Richardson et al., 1995). For example, gray whales 
are known to change direction--deflecting from customary migratory 
paths--in order to avoid noise from seismic surveys (Malme et al., 
1984). Avoidance may be short-term, with animals returning to the area 
once the noise has ceased (e.g., Bowles et al., 1994; Goold, 1996; 
Stone et al., 2000; Morton and Symonds, 2002; Gailey et al., 2007). 
Longer-term displacement is possible, however, which may lead to 
changes in abundance or distribution patterns of the affected species 
in the affected region if habituation to the presence of the sound does 
not occur (e.g., Blackwell et al., 2004; Bejder et al., 2006; Teilmann 
et al., 2006).
    A flight response is a dramatic change in normal movement to a 
directed and rapid movement away from the perceived location of a sound 
source. The flight response differs from other avoidance responses in 
the intensity of the response (e.g., directed movement, rate of 
travel). Relatively little information on flight responses of marine 
mammals to anthropogenic signals exist, although observations of flight 
responses to the presence of predators have occurred (Connor and 
Heithaus, 1996; 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.
    Many animals perform vital functions, such as feeding, resting, 
traveling, and socializing, on a diel cycle (24-hour cycle). Disruption 
of such functions resulting from reactions to stressors such as sound 
exposure are more likely to be significant if they last more than one 
diel cycle or recur on subsequent days (Southall et al., 2007). 
Consequently, a behavioral response lasting less than one day and not 
recurring on subsequent days is not considered particularly severe 
unless it could directly affect reproduction or survival (Southall et 
al., 2007). Note that there is a difference between multi-day 
substantive behavioral reactions and multi-day anthropogenic 
activities. For example, just because an activity lasts for multiple 
days does not necessarily mean that individual animals are either 
exposed to activity-related stressors for multiple days or, further, 
exposed in a manner resulting in sustained multi-day substantive 
behavioral responses.
    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., Selye, 1950; 
Moberg, 2000). In many cases, an animal's first and sometimes most 
economical (in terms of energetic costs) response is behavioral 
avoidance of the potential stressor. Autonomic nervous system responses 
to stress typically involve changes in heart rate, blood pressure, and 
gastrointestinal activity. These responses have a relatively short 
duration and may or may not have a significant long-term effect on an 
animal's fitness.
    Neuroendocrine stress responses often involve the hypothalamus-
pituitary-adrenal system. Virtually all neuroendocrine functions that 
are affected by stress--including immune competence, reproduction, 
metabolism, and behavior--are regulated by pituitary hormones. Stress-
induced changes in the secretion of pituitary hormones have been 
implicated in failed reproduction, altered metabolism, reduced immune 
competence, and behavioral disturbance (e.g., Moberg, 1987; Blecha, 
2000). Increases in the circulation of glucocorticoids are also equated 
with stress (Romano et al., 2004).
    The primary distinction between stress (which is adaptive and does 
not normally place an animal at risk) and ``distress'' is the cost of 
the response. During a stress response, an animal uses glycogen stores 
that can be quickly replenished once the stress is alleviated. In such 
circumstances, the cost of the stress response would not pose serious 
fitness consequences. However, when an animal does not have sufficient 
energy reserves to satisfy the energetic costs of a stress response, 
energy resources must be diverted from other functions. This state of 
distress will last until the animal replenishes its energetic reserves 
sufficient to restore normal function.
    Relationships between these physiological mechanisms, animal 
behavior, and the costs of stress responses are well-studied through 
controlled experiments and for both laboratory and free-ranging animals 
(e.g., Holberton et al., 1996; Hood et al., 1998; Jessop et al., 2003; 
Krausman et al., 2004; Lankford et al., 2005). Stress responses due to 
exposure to anthropogenic sounds or other stressors and their effects 
on marine mammals have also been reviewed (Fair and Becker, 2000; 
Romano et al., 2002b) and, more rarely, studied in wild populations 
(e.g., Romano et al., 2002a).

[[Page 61562]]

For example, Rolland et al. (2012) found that noise reduction from 
reduced ship traffic in the Bay of Fundy was associated with decreased 
stress in North Atlantic right whales. These and other studies lead to 
a reasonable expectation that some marine mammals will experience 
physiological stress responses upon exposure to acoustic 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, 2005), however distress is an 
unlikely result of this project based on observations of marine mammals 
during previous, similar construction projects.
    Auditory Masking--Since many marine mammals rely on sound to find 
prey, moderate social interactions, and facilitate mating (Tyack, 
2008), noise from anthropogenic sound sources can interfere with these 
functions, but only if the noise spectrum overlaps with the hearing 
sensitivity of the receiving marine mammal (Southall et al., 2007; 
Clark et al., 2009; Hatch et al., 2012). Chronic exposure to excessive, 
though not high-intensity, noise could cause masking at particular 
frequencies for marine mammals that utilize sound for vital biological 
functions (Clark et al., 2009). Acoustic masking is when other noises 
such as from human sources interfere with an animal's ability to 
detect, recognize, or discriminate between acoustic signals of interest 
(e.g., those used for intraspecific communication and social 
interactions, prey detection, predator avoidance, navigation) 
(Richardson et al., 1995; Erbe et al., 2016). Therefore, under certain 
circumstances, marine mammals whose acoustical sensors or environment 
are being severely masked could also be impaired from maximizing their 
performance fitness in survival and reproduction. 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 (Hotchkin and 
Parks, 2013).
    Under certain circumstances, marine mammals experiencing 
significant masking could also be impaired from maximizing their 
performance fitness in survival and reproduction. Therefore, when the 
coincident (masking) sound is human-made, it may be considered 
harassment when disrupting or altering critical behaviors. It is 
important to distinguish TTS and PTS, which persist after the sound 
exposure, from masking, which occurs during the sound exposure. Because 
masking (without resulting in TS) is not associated with abnormal 
physiological function, it is not considered a physiological effect, 
but rather a potential behavioral effect.
    The frequency range of the potentially masking sound is important 
in determining any potential behavioral impacts. For example, low-
frequency signals may have less effect on high-frequency echolocation 
sounds produced by odontocetes but are more likely to affect detection 
of mysticete communication calls and other potentially important 
natural sounds such as those produced by surf and some prey species. 
The masking of communication signals by anthropogenic noise may be 
considered as a reduction in the communication space of animals (e.g., 
Clark et al., 2009) and may result in energetic or other costs as 
animals change their vocalization behavior (e.g., Miller et al., 2000; 
Foote et al., 2004; Parks et al., 2007; Di Iorio and Clark, 2010; Holt 
et al., 2009). Masking can be reduced in situations where the signal 
and noise come from different directions (Richardson et al., 1995), 
through amplitude modulation of the signal, or through other 
compensatory behaviors (Hotchkin and Parks, 2013). Masking can be 
tested directly in captive species (e.g., Erbe, 2008), but in wild 
populations it must be either modeled or inferred from evidence of 
masking compensation. There are few studies addressing real-world 
masking sounds likely to be experienced by marine mammals in the wild 
(e.g., Branstetter et al., 2013).
    Marine mammals at or near USCG Air Station Port Angeles may be 
exposed to anthropogenic noise which may lead to some habituation, but 
is also a source of masking. Vocalization changes may result from a 
need to compete with an increase in background noise and include 
increasing the source level, modifying the frequency, increasing the 
call repetition rate of vocalizations, or ceasing to vocalize in the 
presence of increased noise (Hotchkin and Parks, 2013).
    Masking is more likely to occur in the presence of broadband, 
relatively continuous noise sources. Energy distribution of pile 
driving covers a broad frequency spectrum, and sound from pile driving 
would be within the audible range of pinnipeds and cetaceans present in 
the proposed action area. While some construction activities during the 
proposed project may mask some acoustic signals that are relevant to 
the daily behavior of marine mammals, the short-term duration and 
limited areas affected make it very unlikely that any masking effects 
would interfere with critical life functions, and therefore masking 
from construction noise would be unlikely to have any impacts on 
survival or reproduction of individuals.
    Airborne Acoustic Effects--Pinnipeds that occur near the project 
site could be exposed to airborne sounds associated with construction 
activities that have the potential to cause behavioral harassment, 
depending on their distance from these activities. 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 
airborne acoustic criteria. Although pinnipeds are known to haul out 
regularly on man-made objects, we believe that incidents of take 
resulting solely from airborne sound are unlikely due to the proximity 
between the proposed project area and the known haulout sites (e.g., 
the nearest harbor seal haulouts are 2.4 km and 3.5 km away (2.18 mi)). 
Cetaceans are not expected to be exposed to airborne sounds that would 
result in harassment as defined under the MMPA.
    We recognize that pinnipeds in the water could be exposed to 
airborne sound that may result in behavioral harassment when looking 
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 here.

Potential Effects on Marine Mammal Habitat

    The proposed project will occur within the same footprint as 
existing marine infrastructure. The nearshore

[[Page 61563]]

and intertidal habitat where the proposed project will occur is an area 
of relatively high marine vessel traffic. Most marine mammals do not 
generally use the area within the footprint of the project area. 
Temporary, intermittent, and short-term habitat alteration may result 
from increased noise levels within the Level A and Level B harassment 
zones. Effects on marine mammals will be limited to temporary 
displacement from pile installation and removal noise, and effects on 
prey species will be similarly limited in time and space.
    Water quality--Temporary and localized reduction in water quality 
will occur as a result of in-water construction activities. Most of 
this effect will occur during the installation and removal of piles 
when bottom sediments are disturbed. The installation and removal of 
piles may cause a temporary increase in suspended sediment in the 
project area. During pile extraction, sediment attached to the pile 
moves vertically through the water column until gravitational forces 
cause it to slough off under its own weight. The small resulting 
sediment plume is expected to 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 to turbidity and sedimentation are expected to be short-
term, minor, and localized. Since the currents are so strong in the 
area, following the completion of sediment-disturbing activities, 
suspended sediments 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, turbidity plumes 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 
available marine mammal habitat in Port Angeles Harbor and the Strait 
of Juan de Fuca.
    Potential Effects on Prey--Sound may affect marine mammals through 
impacts on the abundance, behavior, or distribution of prey species 
(e.g., crustaceans, cephalopods, fishes, zooplankton). Marine mammal 
prey varies by species, season, and location and, for some, is not well 
documented. Studies regarding the effects of noise on known marine 
mammal prey are described here.
    Fishes utilize the soundscape and components of sound in their 
environment to perform important functions such as foraging, predator 
avoidance, mating, and spawning (e.g., Zelick et al., 1999; Fay, 2009). 
Depending on their hearing anatomy and peripheral sensory structures, 
which vary among species, fishes hear sounds using pressure and 
particle motion sensitivity capabilities and detect the motion of 
surrounding water (Fay et al., 2008). The potential effects of noise on 
fishes depends on the overlapping frequency range, distance from the 
sound source, water depth of exposure, and species-specific hearing 
sensitivity, anatomy, and physiology. Key impacts to fishes may include 
behavioral responses, hearing damage, barotrauma (pressure-related 
injuries), and mortality.
    Fish react to sounds that are especially strong and/or intermittent 
low-frequency sounds. Short duration, sharp sounds can cause overt or 
subtle changes in fish behavior and local distribution. The reaction of 
fish to noise depends on the physiological state of the fish, past 
exposures, motivation (e.g., feeding, spawning, migration), and other 
environmental factors. (Hastings and Popper, 2005) identified several 
studies that suggest fish may relocate to avoid certain areas of sound 
energy. Additional studies have documented effects of pile driving on 
fishes (e.g. Scholik and Yan, 2001; 2002; Popper and Hastings, 2009). 
Several studies have demonstrated that impulse sounds might affect the 
distribution and behavior of some fishes, potentially impacting 
foraging opportunities or increasing energetic costs (e.g., Fewtrell 
and McCauley, 2012; Pearson et al., 1992; Skalski et al., 1992; 
Santulli et al., 1999; Paxton et al., 2017). However, some studies have 
shown no or slight reaction to impulse sounds (e.g., Pe[ntilde]a et 
al., 2013; Wardle et al., 2001; Jorgenson and Gyselman, 2009; Cott et 
al., 2012. More commonly, though, the impacts of noise on fishes are 
temporary.
    SPLs of sufficient strength have been known to cause injury to 
fishes 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; Casper et al., 2017).
    Fish populations in the proposed project area that serve as marine 
mammal prey could be temporarily affected by noise from pile 
installation and removal. The frequency range in which fishes generally 
perceive underwater sounds is 50 to 2,000 Hz, with peak sensitivities 
below 800 Hz (Popper and Hastings, 2009). Fish behavior or distribution 
may change, especially with strong and/or intermittent sounds that 
could harm fishes. High underwater SPLs have been documented to alter 
behavior, cause hearing loss, and injure or kill individual fish by 
causing serious internal injury (Hastings and Popper, 2005).
    The greatest potential impact to fishes during construction would 
occur during impact pile driving. However, the duration of impact pile 
driving would be limited to the final stage of installation 
(``proofing'') after the pile has been driven as close as practicable 
to the design depth with a vibratory driver. In-water construction 
activities would only occur during daylight hours, allowing fish to 
forage and transit the project area in the evening. Vibratory pile 
driving may elicit behavioral reactions from fishes such as temporary 
avoidance of the area but is unlikely to cause injuries to fishes 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 highly developed and experiences a high level of 
anthropogenic noise from normal port operations and other vessel 
traffic. In general, impacts on marine mammal prey species are expected 
to be minor and temporary.

In-Water Construction Effects on Potential Foraging Habitat

    The proposed activities would not result in permanent impacts to 
habitats used directly by marine mammals. 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 outside

[[Page 61564]]

this project area. Construction would have minimal permanent and 
temporary impacts on benthic invertebrate species, a marine mammal prey 
source. In addition, although the Strait of Juan de Fuca is valuable 
habitat for many marine mammal species, the area within Port Angeles 
Harbor is not particularly high-value foraging habitat due to the high 
level of anthropogenic activity associated with normal port operations. 
Therefore, impacts of the project are not likely to have adverse 
effects on marine mammal foraging habitat in the proposed project area.
    The area impacted by the project is relatively small compared to 
the available habitat just outside the project area, and there are no 
areas of particular importance that would be impacted by this project. 
Any behavioral avoidance by fish of the disturbed area would still 
leave significantly large areas of fish and marine mammal foraging 
habitat in the nearby vicinity. As described in the preceding, the 
potential for the Coast Guard's construction to affect the availability 
of prey to marine mammals or to meaningfully impact the quality of 
physical or acoustic habitat is considered to be insignificant.

Estimated Take of Marine Mammals

    This section provides an estimate of the number of incidental takes 
proposed for authorization through this IHA, which will inform both 
NMFS' consideration of ``small numbers,'' and the negligible impact 
determinations.
    Harassment is the only type of take expected to result from these 
activities. Except with respect to certain activities not pertinent 
here, section 3(18) of the MMPA defines ``harassment'' as any act of 
pursuit, torment, or annoyance, which (i) has the potential to injure a 
marine mammal or marine mammal stock in the wild (Level A harassment); 
or (ii) has the potential to disturb a marine mammal or marine mammal 
stock in the wild by causing disruption of behavioral patterns, 
including, but not limited to, migration, breathing, nursing, breeding, 
feeding, or sheltering (Level B harassment).
    Authorized takes would be by Level B harassment only, in the form 
of disruption of behavioral patterns and/or TTS for individual marine 
mammals resulting from exposure to noise from impact and vibratory pile 
driving. Based on the nature of the activity and the anticipated 
effectiveness of the mitigation measures (i.e., shutdown zones 
implemented at no less than the distance to the Level A isopleths) 
discussed in detail below in the Proposed Mitigation section, Level A 
harassment is neither anticipated nor proposed to be authorized.
    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 thresholds above which NMFS believes the best 
available science indicates marine mammals will be behaviorally 
harassed or incur some degree of permanent hearing impairment; (2) the 
area or volume of water that will be ensonified above these levels in a 
day; (3) the density or occurrence of marine mammals within these 
ensonified areas; and, (4) 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 Thresholds

    NMFS recommends the use of acoustic thresholds that identify the 
received level of underwater sound above which exposed marine mammals 
would be reasonably expected to be behaviorally harassed (equated to 
Level B harassment) or to incur PTS of some degree (equated to Level A 
harassment).
    Level B Harassment--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.
    Coast Guard's proposed activity includes the use of continuous 
(e.g., vibratory pile installation and extraction) and impulsive (e.g, 
impact pile installation) sources, and therefore the RMS SPL thresholds 
of 120 and 160 dB re 1 [mu]Pa are applicable.
    Level A Harassment--NMFS' Technical Guidance for Assessing the 
Effects of Anthropogenic Sound on Marine Mammal Hearing (Version 2.0) 
(Technical Guidance, 2018) identifies dual criteria to assess auditory 
injury (Level A harassment) to five different marine mammal groups 
(based on hearing sensitivity) as a result of exposure to noise from 
two different types of sources (impulsive or non-impulsive). Coast 
Guard's proposed construction activity includes the use of non-
impulsive (e.g., vibratory pile installation and extraction) and 
impulsive (e.g, impact pile installation) sources.
    These thresholds are provided in Table 4, below. The references, 
analysis, and methodology used in the development of the thresholds are 
described in NMFS' 2018 Technical Guidance, which may be accessed at: 
www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance.

[[Page 61565]]



                     Table 4--Thresholds Identifying the Onset of Permanent Threshold Shift
----------------------------------------------------------------------------------------------------------------
                                                    PTS onset acoustic thresholds \*\ (received level)
             Hearing group              ------------------------------------------------------------------------
                                                  Impulsive                         Non-impulsive
----------------------------------------------------------------------------------------------------------------
Low-Frequency (LF) Cetaceans...........  Cell 1: Lpk,flat: 219 dB;   Cell 2: LE,LF,24h: 199 dB.
                                          LE,LF,24h: 183 dB.
Mid-Frequency (MF) Cetaceans...........  Cell 3: Lpk,flat: 230 dB;   Cell 4: LE,MF,24h: 198 dB.
                                          LE,MF,24h: 185 dB.
High-Frequency (HF) Cetaceans..........  Cell 5: Lpk,flat: 202 dB;   Cell 6: LE,HF,24h: 173 dB.
                                          LE,HF,24h: 155 dB.
Phocid Pinnipeds (PW) (Underwater).....  Cell 7: Lpk,flat: 218 dB;   Cell 8: LE,PW,24h: 201 dB.
                                          LE,PW,24h: 185 dB.
Otariid Pinnipeds (OW) (Underwater)....  Cell 9: Lpk,flat: 232 dB;   Cell 10: LE,OW,24h: 219 dB.
                                          LE,OW,24h: 203 dB.
----------------------------------------------------------------------------------------------------------------
* Dual metric acoustic thresholds for impulsive sounds: Use whichever results in the largest isopleth for
  calculating PTS onset. If a non-impulsive sound has the potential of exceeding the peak sound pressure level
  thresholds associated with impulsive sounds, these thresholds should also be considered.
Note: Peak sound pressure (Lpk) has a reference value of 1 [micro]Pa, and cumulative sound exposure level (LE)
  has a reference value of 1[micro]Pa\2\s. In this Table, thresholds are abbreviated to reflect American
  National Standards Institute standards (ANSI 2013). However, peak sound pressure is defined by ANSI as
  incorporating frequency weighting, which is not the intent for this Technical Guidance. Hence, the subscript
  ``flat'' is being included to indicate peak sound pressure should be flat weighted or unweighted within the
  generalized hearing range. The subscript associated with cumulative sound exposure level thresholds indicates
  the designated marine mammal auditory weighting function (LF, MF, and HF cetaceans, and PW and OW pinnipeds)
  and that the recommended accumulation period is 24 hours. The cumulative sound exposure level thresholds could
  be exceeded in a multitude of ways (i.e., varying exposure levels and durations, duty cycle). When possible,
  it is valuable for action proponents to indicate the conditions under which these acoustic thresholds will be
  exceeded.

Ensonified Area

    Here, we describe operational and environmental parameters of the 
activity that are used in estimating the area ensonified above the 
acoustic thresholds, including source levels and transmission loss 
coefficient.
    The sound field in the project area 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 (i.e., impact pile driving and 
vibratory pile installation and removal). Calculation of the area 
ensonified by the proposed action is dependent on source levels of the 
proposed activities and the estimated transmission loss coefficients 
for the proposed activities at the site. These factors are addressed 
below.
    Sound Source Levels of Proposed Activities--The intensity of pile 
driving sounds is greatly influenced by factors such as the type of 
piles (material and diameter), hammer type, and the physical 
environment (e.g., sediment type) in which the activity takes place. In 
order to calculate the distances to the Level A harassment and the 
Level B harassment thresholds for the methods and piles being used in 
this project, the Coast Guard used acoustic monitoring data from sound 
source verification studies to develop proxy source levels for the 
various pile types, sizes and methods (Table 5).

                                                  Table 5--Pile Installation and Extraction Parameters
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                     Proxy levels (@10m)
                                                                                             -----------------------------------
           Pile type                  Method         Total    Number    Strikes per pile OR    dB re 1   dB re 1     dB re 1            Reference
                                                    number    per day      hours per day       [mu]Pa    [mu]Pa   [micro]Pa\2\s
                                                                                                peak       RMS        SELss
--------------------------------------------------------------------------------------------------------------------------------------------------------
12-in steel...................  Impact...........        37         5  100 strikes..........       192       177          166    CALTRANS 2020.
12-in steel...................  Vibratory                37        10  5 hrs................  ........       155  .............  Greenbusch 2018.
                                 installation.
18-in steel...................  Vibratory                 3         2  1 hr.................  ........       158  .............  CALTRANS 2020.
                                 installation.
12--14-in timber..............  Vibratory                48        16  8 hrs................  ........       160  .............  Greenbusch 2018.
                                 extraction.
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Transmission Loss--Transmission loss (TL) is the decrease in 
acoustic intensity as an acoustic pressure wave propagates out from a 
source. TL parameters vary with frequency, temperature, sea conditions, 
current, source and receiver depth, water depth, water chemistry, and 
bottom composition and topography. The general formula for underwater 
TL is:

TL = B * Log10 (R1/R2),
where:

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

    This formula neglects loss due to scattering and absorption, which 
is assumed to be zero here. The degree to which underwater sound 
propagates away from a sound source is dependent on a variety of 
factors, most notably the bathymetry and presence or absence of 
reflective or absorptive conditions including in-water structures and 
sediments. Spherical spreading occurs in a perfectly unobstructed 
(free-field) environment not limited by depth or water surface, 
resulting in a 6 dB reduction in sound level for each doubling of 
distance from the source (20*log10[range]). Cylindrical 
spreading occurs in an environment in which sound propagation is 
bounded by the water surface and sea bottom, resulting in a reduction 
of 3 dB in sound level for each doubling of distance from the source 
(10* log10[range]). A practical spreading value of 15 is 
often used under conditions where water increases with depth as the 
receiver moves away from the shoreline, resulting in an expected 
propagation environment that would lie between spherical and 
cylindrical spreading loss conditions.
    Site-specific transmission loss measurements are not available for 
Port Angeles Harbor. NMFS has therefore used the practical spreading 
loss model for both vibratory and impact pile driving in this analysis.
    Estimated Harassment Isopleths--All Level B harassment isopleths 
are reported in Table 6. Level B harassment isopleths from the proposed 
project will be limited by the coastline along and across from the 
project site. The maximum attainable isopleth distance is

[[Page 61566]]

4,642 m during vibratory extraction of timber piles (see Figure 1 in 
the IHA application for further detail).
    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 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, including 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 PTS. Inputs used in the User Spreadsheet (e.g., 
number of piles per day, duration and/or strikes per pile, source 
levels) are presented in Table 1 and Table 5. The resulting isopleths 
and ensonified areas are reported in Table 6 and Table 7, respectively.

                                                        Table 6--Estimated Isopleths by Activity
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                  Underwater                           Airborne Level B
                                                                          ----------------------------------------------------------      harassment
                                                                                 Level A harassment isopleths [m]         Level B       isopleths [m]
                 Activity                               Method            ---------------------------------------------  harassment --------------------
                                                                                                                         isopleths    Harbor     Other
                                                                              LF       MF       HF       PW       OW        [m]        Seals   Pinnipeds
--------------------------------------------------------------------------------------------------------------------------------------------------------
12-in steel...............................  Impact.......................     46.0      1.6     55.0     25.0      2.0        136.0       150         47
12-in steel...............................  Vibratory installation.......      8.0      0.7     11.8      4.8      0.3        2,154        19          6
18-in steel...............................  Vibratory installation.......      4.3      0.4      6.4      2.6      0.2        3,415
12-14-in timber...........................  Vibratory extraction.........     23.4      2.1     34.6     14.2      1.0        4,642
--------------------------------------------------------------------------------------------------------------------------------------------------------


                                                                Table 7--Areas Ensonified
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                    Level A harassment [km\2\]                 Level B
                    Activity                                    Method               -------------------------------------------------------  harassment
                                                                                          LF         MF         HF         PW         OW       [km\2\]
--------------------------------------------------------------------------------------------------------------------------------------------------------
12-in steel.....................................  Impact............................       0.02      <0.01       0.02       0.01      <0.01         0.07
12-in steel.....................................  Vibratory installation............      <0.01      <0.01      <0.01      <0.01      <0.01         7.74
18-in steel.....................................  Vibratory installation............      <0.01      <0.01      <0.01      <0.01      <0.01        14.52
12-14-in timber.................................  Vibratory extraction..............       0.01      <0.01       0.02      <0.01      <0.01        17.59
--------------------------------------------------------------------------------------------------------------------------------------------------------

Marine Mammal Occurrence

    In this section we provide information about the occurrence of 
marine mammals, including density or other relevant information which 
will inform the take calculations.
    For marine mammal density information in the Port Angeles area we 
used data from the Pacific Navy Marine Species Density Database (U.S. 
Navy, 2019) to estimate take for marine mammals. The Marine Species 
Density Database incorporates analyzed literature and research for 
marine mammal density estimates per season for the Gulf of Alaska and 
the West Coast of the United States. Density estimates specific to the 
Strait of Juan de Fuca are not available for any of the species 
addressed in this application, and therefore takes were estimated based 
on the nearest available and most appropriate density estimates, plus 
site-specific knowledge and professional judgement. Table 8 density 
estimates are calculated based on the in-water work window (July--
February) and based on the highest seasonal density estimates for the 
relevant area.

        Table 8--Seasonal Density of Species in the Project Area
------------------------------------------------------------------------
                Species                     Densities (animals/km\2\)
------------------------------------------------------------------------
Humpback whale.........................  0.0027 (summer/fall).
Killer whale--Southern Resident........  0.0012 (summer).
Killer whale--Transient................  0.0208 (fall).
Harbor porpoise........................  2.16 (annual).
Harbor seal............................  0.76 (summer/fall).
Northern elephant seal.................  0.0029 (fall).
Steller sea lion.......................  0.0027 (fall/winter).
California sea lion....................  0.300 (September).
------------------------------------------------------------------------

Take Estimation

    Here we describe how the information provided above is synthesized 
to produce a quantitative estimate of the take that is reasonably 
likely to occur and proposed for authorization.
    Using the overall area of disturbance generated by pile removal and 
installation given calculated distances to attenuation below 
disturbance (Level B harassment) thresholds, incidental take for each 
activity is estimated by the following equation: Incidental take

[[Page 61567]]

estimate = species density * ensonified area * days of pile-related 
activity.
    This equation is a reasonable extrapolation for take estimates, 
which relies on the likelihood that a species is present within the 
ensonified area on a day where the proposed activity is occurring. Take 
estimates were calculated with the conservative assumption that each 
activity (i.e., vibratory extraction of steel piles, vibratory 
extraction of timber piles, vibratory installation, and impact 
installation) would occur on separate days, using a maximum of 23 days 
of in-water work. However, the Coast Guard would perform some 
activities on the same day, resulting in reduced numbers of overall 
take during the proposed 15 days of pile driving.
    No take by Level A harassment is proposed for any species of marine 
mammal due to the small zones, in conjunction with Coast Guard's 
proposed shutdown mitigation measure. Shutdown zones would be enforced 
at the extent of the estimated Level A harassment isopleth for all 
species groups except for large whales (i.e., baleen whales, including 
humpbacks, and killer whales). The Coast Guard has proposed to shut 
down for killer whales upon observation regardless of location in order 
to prevent potential take of members of the Southern Resident stock, 
and shutdown zones for other large whale species would be enforced at 
the extent of the Level B harassment isopleths. Given the remote 
likelihood of large whale species entering Port Angeles Harbor during 
the 15 days of pile driving work (see calculated take estimates for 
humpback and killer whales in Table 9) and the locations of Protected 
Species Observers (PSOs) described in the Proposed Monitoring and 
Reporting section, NMFS agrees that monitoring and shutdown measures 
are likely to be successful at avoiding take of these species. 
Therefore, no take of large whale species (including but not limited to 
humpback and killer whales) has been requested and none is proposed for 
authorization.
    Based on sightings reported during the 2016-2017 Navy TPS Port 
Angeles project (Northwest Environmental Consulting, LLC 2018), Coast 
Guard anticipates the number of harbor seals present in the project 
area during the proposed in-water activities may exceed calculated 
exposure estimates. During the 2016-2017 Navy TPS Port Angeles project, 
275 harbor seals were observed in the estimated Level B harassment zone 
over approximately 45 days during which pile driving occurred 
(Northwest Environmental Consulting, LLC., 2018). The Coast Guard 
project will have only 15 days of in-water pile driving. Therefore, 
Coast Guard has requested, and NMFS proposes to authorize, 210 
incidents of Level B harassment for harbor seals, approximately half 
the difference in sightings between the 2016-2017 Navy TPS Port Angeles 
project and the exposure estimate for this project.

                                   Table 9--Calculated and Proposed Authorized Amount of Taking and Percent of Stocks
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                 Take by Level A           Take by Level B
                                                                                   harassment                harassment                       Percent of
                  Species                                Stock             ----------------------------------------------------  Total take     stock
                                                                             Calculated    Proposed    Calculated    Proposed
--------------------------------------------------------------------------------------------------------------------------------------------------------
Humpback whale.............................  Hawai'i......................            0            0         0.51            0            0            0
                                             Mainland Mexico--CA/OR/WA....
                                             Central America/Southern
                                              Mexico--CA/OR/WA.
Killer whale...............................  Eastern North Pacific                    0            0         0.23            0            0            0
                                              Southern Resident.
                                             West Coast Transient.........            0            0         3.94            0            0            0
Harbor porpoise............................  Washington Inland Waters.....         0.73            0        408.9          409          409         4.92
Harbor seal................................  Washington Northern Inland            0.13            0        143.9          210          210       \1\ NA
                                              Waters.
Northern Elephant Seal.....................  CA Breeding..................            0            0         0.55            1            1        <0.01
Steller Sea Lion...........................  Eastern......................            0            0         0.51            1            1        <0.01
California Sea lion........................  U.S..........................          0.1            0         56.8           57           57         0.02
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Stock size for the Washington Northern Inland Waters stock of harbor seals is not available from the most recent SARs due to a lack of recent data.

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 
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.
    Shutdown Zones--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 mammal (or in anticipation of an animal entering 
the defined area). Construction supervisors and crews, Protected 
Species Observers (PSO), and relevant Coast Guard staff must avoid 
direct physical interaction with marine mammals during construction 
activities, which could include (but are not limited to) the following: 
(1) barge movement to the pile location; (2) pile positioning on the 
substrate via a crane (i.e., stabbing the pile); and (3) pile removal 
from the water column/substrate via a crane (i.e., deadpull). If a 
marine mammal comes within 10

[[Page 61568]]

meters of such activity, operations must cease and vessels must reduce 
speed to the minimum level required to maintain steerage and safe 
working conditions, as necessary to avoid direct physical interaction.
    Further, Coast Guard must implement activity-specific shutdown 
zones as described in Table 10. The shutdown zone for humpback whales 
or other non-authorized marine mammal species (except killer whales) 
would be the predicted Level B harassment isopleth. For these species, 
project activity may resume after the animal has not been observed for 
15 minutes, or has been observed leaving the shutdown zone (i.e., the 
Level B harassment zone). As proposed by the Coast Guard, killer whales 
will require a shutdown upon observation no matter location in order to 
prevent take of members of the Southern Resident stock. If killer 
whales are sighted, the project activity would resume only after the 
killer whale is not observed for 15 minutes.

                                                            Table 10--Required Shutdown Zones
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                              Shutdown zone (m)                               Monitoring
                                                                ----------------------------------------------------------------------------  zone (m)--
              Pile type                   Pile driving method                                                                                all species
                                                                       Killer whales          LF        MF        HF        PW        OW
--------------------------------------------------------------------------------------------------------------------------------------------------------
Steel................................  Vibratory...............  Any sighting at any          3,415                    12                          3,415
                                                                  distance.
                                       Impact..................                                 136                    55                            136
Timber...............................  Vibratory...............                               4,642                    35                          4,642
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Protected Species Observers--The placement of PSOs during all 
construction activities (described in the Proposed Monitoring and 
Reporting section) would ensure that the entire shutdown zone is 
visible. Coast Guard would employ three PSOs for vibratory installation 
and extraction of steel and timber piles. Two PSOs would be land-based, 
while one would be positioned on a vessel to ensure full monitoring 
coverage to the estimated Level B harassment isopleth. For impact pile 
driving activities, Coast Guard would employ one PSO.
    Pre and Post-Activity Monitoring-Monitoring--must take place from 
30 minutes prior to initiation of pile driving activity (i.e., pre-
start clearance monitoring) through 30 minutes post-completion of pile 
driving activity. Pre-start clearance monitoring must be conducted 
during periods of visibility sufficient for the lead PSO to determine 
that the shutdown zones indicated in Table 10 are clear of marine 
mammals. Pile driving may commence following 30 minutes of observation 
when the determination is made that the shutdown zones are clear of 
marine mammals. If a marine mammal is observed entering or within the 
shutdown zones, pile driving activity must be delayed or halted. If 
pile driving is delayed or halted due to the presence of a marine 
mammal, the activity may not commence or resume until either the animal 
has voluntarily exited and been visually confirmed beyond the shutdown 
zone or 15 minutes have passed without re-detection of the animal. If a 
marine mammal for which take by Level B harassment is authorized is 
present in the Level B harassment zone, activities would begin and 
Level B harassment take would be recorded.
    Monitoring for Level B Harassment--PSOs would monitor the shutdown 
zones and beyond to the extent that PSOs can see. For this activity, 
the monitoring zone is defined as the largest predicted Level B 
harassment isopleth for a given activity (Table 10). Monitoring beyond 
the shutdown zones 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. If weather or sea conditions restrict 
the observer's ability to observe the monitoring zone, pile driving 
activities must cease until conditions are favorable for observations 
to resume.
    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 leave the area prior to the hammer operating at 
full capacity. For impact pile driving, soft start requires contractors 
to provide an initial set of three strikes at reduced energy, followed 
by a 30-second waiting period, then two subsequent reduced-energy 
strike sets. A soft start must be implemented at the start of each 
day's impact pile driving and at any time following cessation of impact 
pile driving for a period of 30 minutes or longer.
    If unsafe working conditions during ramp ups are reported (e.g., 
crane failure from excess wear due to the ramp up procedure) by the 
contractor and verified by an independent safety inspection, the Coast 
Guard may elect to discontinue impact driver ramp ups. The Coast Guard 
will inform NMFS if the ramp up procedure is discontinued. If use of a 
variable moment driver is infeasible and the model of impact driver was 
not specifically designed for ramp up procedures, then the Coast Guard 
will not employ impact ramp up procedures due to personnel safety 
concerns.
    In-water Work Window--To reduce impacts to marine fishes, the Coast 
Guard will follow the in-water work window designated for the Strait of 
Juan de Fuca and associated bays and inlets by the U.S. Army Corps of 
Engineers. The work window extends from July 16 to February 15; no in-
water work will be conducted outside of that date range unless a 
modification is negotiated with the relevant regulatory agencies, 
including the U.S. Army Corps of Engineers.
    NMFS and Coast Guard considered the use of bubble curtains as a 
mitigation measure during this project. However, based on the limited 
amount of impact driving expected, the relatively small estimated Level 
A harassment isopleths, and the potential for increased turbidity 
during bubble curtain use, NMFS has determined that use of a bubble 
curtain would not further reduce take of marine mammals during this 
project and they are not included in the proposed mitigation methods.
    Based on our evaluation of the applicant's proposed measures, as 
well as other measures considered by NMFS, NMFS has preliminarily 
determined that the proposed mitigation measures provide the means 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

[[Page 61569]]

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 Plan, dated July 2023, available online at 
https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities. Marine mammal 
monitoring during pile driving and removal must be conducted by NMFS-
approved PSOs 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 must have prior experience performing the 
duties of a PSO during construction activity pursuant to a NMFS-issued 
incidental take authorization;
     Other PSOs may substitute other relevant experience, 
education (degree in biological science or related field) or training 
for experience performing the duties of a PSO during construction 
activities pursuant to a NMFS-issued incidental take authorization;
     Where a team of three or more PSOs is required, a lead 
observer or monitoring coordinator must be designated. The lead 
observer must have prior experience performing the duties of a PSO 
during construction activity pursuant to a NMFS-issued incidental take 
authorization; and
     PSOs must be approved by NMFS prior to beginning any 
activity 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.
    A team of one to two land based PSOs would be deployed to observe 
the monitoring zones for vibratory and impact pile driving during this 
project. PSOs will be located at the best vantage points to see the 
entirety of the active zone. One PSO will have an unobstructed view of 
all water within the shutdown zones, and will be stationed at or near 
the project activity. While the exact monitoring stations have not yet 
been determined, Coast Guard provided potential locations in Figure 1 
of its Marine Mammal Monitoring and Mitigation Plan. Additionally, a 
PSO will be stationed for monitoring on an observation vessel in order 
to ensure the entire monitoring zone to the extent of the relevant 
predicted Level B harassment isopleth can be observed during vibratory 
pile installation and removal.
    Monitoring would be conducted 30 minutes before, during, and 30 
minutes after all in water construction activities. In addition, PSOs 
would record all incidents of marine mammal occurrence, regardless of 
distance from activity, and would document any behavioral reactions in 
concert with distance from piles being driven or removed. Pile driving 
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.

Reporting

    Coast Guard would submit a draft report to NMFS within 90 calendar 
days of the completion of monitoring or 60 calendar days prior to the 
requested issuance of any subsequent IHA for construction activity at 
the same location, whichever comes first. The marine mammal monitoring 
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: (1) The number and type of piles that 
were driven and the method (e.g., impact or vibratory); and (2) Total 
duration of driving time for each pile (vibratory driving) and number 
of strikes for each pile (impact driving);
     PSO locations during marine mammal monitoring;
     Environmental conditions during monitoring periods (at 
beginning and end of PSO shift and whenever conditions change 
significantly), including Beaufort sea state and any other relevant 
weather conditions including cloud cover, fog, sun glare, and overall 
visibility to the horizon, and estimated observable distance;
     Upon observation of a marine mammal, the following 
information: (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 location of each observed marine mammal relative to the 
pile being driven for each sighting; (5) Estimated number of animals 
(min/max/best estimate); (6)

[[Page 61570]]

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; (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 implementation of any 
mitigation (e.g., shutdowns and delays), a description of specific 
actions that ensued, and resulting changes in behavior of the 
animal(s), if any.
    A final report must be prepared and submitted within 30 calendar 
days following receipt of any NMFS comments on the draft report. If no 
comments are received from NMFS within 30 calendar days of receipt of 
the draft report, the report shall be considered final.
    In the event that personnel involved in the construction activities 
discover an injured or dead marine mammal, the Holder must report the 
incident to the OPR, NMFS ([email protected] and 
[email protected]) and to the West Coast regional stranding network 
(866-767-6114) as soon as feasible. If the death or injury was clearly 
caused by the specified activity, the Holder must immediately cease the 
activities until NMFS OPR 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 this IHA. The Holder 
must not resume their activities until notified by NMFS.
    The report must include the following information:
    [ssquf] Time, date, and location (latitude/longitude) of the first 
discovery (and updated location information if known and applicable);
    [ssquf] Species identification (if known) or description of the 
animal(s) involved;
    [ssquf] Condition of the animal(s) (including carcass condition if 
the animal is dead);
    [ssquf] Observed behaviors of the animal(s), if alive;
    [ssquf] If available, photographs or video footage of the 
animal(s); and
    [ssquf] 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 9, 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 activities associated with the project, as 
outlined previously, have the potential to disturb or displace marine 
mammals. Specifically, the specified activities may result in take, in 
the form of Level B harassment, from underwater sounds generated from 
pile driving and removal. Potential takes could occur if individuals of 
these species are present in zones ensonified above the thresholds for 
Level B harassment, identified above, when these activities are 
underway.
    The takes by Level B harassment would be due to potential 
behavioral disturbance. No mortality or serious injury is anticipated 
given the nature of the activity, and no Level A harassment is 
anticipated due to Coast Guard's construction method and proposed 
mitigation measures (see Proposed Mitigation section).
    Effects on individuals that are taken by Level B harassment, on the 
basis of reports in the literature as well as monitoring from other 
similar activities, would likely be limited to reactions such as 
increased swimming speeds, increased surfacing time, or decreased 
foraging (if such activity were occurring; e.g., Thorson and Reyff 
2006; HDR, Inc. 2012; Lerma 2014; ABR 2016). Most likely, individuals 
would simply move away from the sound source and be temporarily 
displaced from the areas of pile driving and removal, although even 
this reaction has been observed primarily only in association with 
impact pile driving, which Coast Guard anticipates using for only 10 
percent of pile driving. If sound produced by project activities is 
sufficiently disturbing, animals are likely to simply avoid the area 
while the activity is occurring, particularly as the project is 
expected to occur over just 15 in-water pile driving days.
    The project is also not expected to have significant adverse 
effects on affected marine mammals' habitats. The project activities 
would not modify existing marine mammal habitat for a significant 
amount of time. The activities may cause some fish to leave the area of 
disturbance, thus temporarily impacting marine mammals' foraging 
opportunities in a limited portion of the foraging range. Given the 
short duration of the activities and the relatively small area of the 
habitat that may be affected, the impacts to marine mammal habitat, 
including fish, are not expected to cause significant or long-term 
negative consequences.
    There are two known harbor seal haulouts close to the project site. 
The first haulout site is directly across Port Angeles Harbor from the 
USCG Air Station, approximately 2.4 km away. Seals swimming to and from 
this haulout have the potential to experience Level B harassment due to 
underwater sound exposure during vibratory or impact pile driving 
activities. However, the project activities are not expected to occur 
during any particularly sensitive time (e.g., molting or pupping 
season), and the project duration is short, with

[[Page 61571]]

approximately 15 days of in-water work. Given the availability of a 
second haulout close by (3.5 km (2.17 mi) from the project site on the 
opposite side of Ediz Hook) which is not expected to be exposed to 
noise from pile driving and the short duration of the project, there 
are no anticipated significant or long-term negative consequences to 
harbor seals in 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;
     The anticipated incidents of Level B harassment would 
consist of, at worst, temporary modifications in behavior that would 
not result in fitness impacts to individuals;
     Take estimates were calculated assuming that no activities 
would occur on the same day. However, in reality, vibratory and impact 
driving are likely to occur on the same day, reducing the overall 
impact to marine mammal species;
     The area impacted by the specified activity is very small 
relative to the overall habitat ranges of all species;
     While impacts would occur within areas that are important 
for feeding or resting for multiple stocks, because of the small 
footprint of the activity relative to the area of these important use 
areas, and the scope and nature of the anticipated impacts of pile 
driving exposure, we do not expect impacts to the reproduction or 
survival of any individuals.
    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 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 number of instances of take for each species or stock proposed 
to be taken as a result of this project is included in Table 9. Our 
analysis shows that less than one-third of the best available 
population abundance estimate of each stock could be taken by 
harassment. The number of animals proposed to be taken for all stocks 
would be considered small relative to the relevant stock's abundances 
even if each estimated taking occurred to a new individual, which is an 
unlikely scenario.
    A lack of an accepted stock abundance value for the Washington 
Northern Inland Waters stock of harbor seal did not allow for the 
calculation of an expected percentage of the population that would be 
affected. The most relevant estimate of partial stock abundance is 
7,513 seals (CV = 11.5%) (Jefferson et al. 2021). Given 210 proposed 
takes by Level B harassment for the stock, comparison to the best 
estimate of stock abundance shows, at most, 2.8 percent of the stock 
would be expected to be impacted.
    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

    There are no relevant subsistence uses of the affected marine 
mammal stocks or species implicated by this action. Therefore, NMFS has 
determined that the total taking of affected species or stocks would 
not have an unmitigable adverse impact on the availability of such 
species or stocks for taking for subsistence purposes.

Endangered Species Act

    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 consults 
internally whenever we propose to authorize take for endangered or 
threatened species.
    No incidental take of ESA-listed species is proposed for 
authorization or expected to result from this activity. Therefore, NMFS 
has determined that formal consultation under section 7 of the ESA is 
not required for this action.

Proposed Authorization

    As a result of these preliminary determinations, NMFS proposes to 
issue an IHA to the Coast Guard for conducting Pier Maintenance and 
Bank Stabilization at USCG Air Station Port Angeles, in Port Angeles, 
Washington, between November 15, 2023 and November 14, 2024 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.

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 Pier 
Maintenance and Bank Stabilization. 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, one-year 
renewal IHA following notice to the public providing an additional 15 
days for public comments when (1) up to another year of identical or 
nearly identical 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 one year from 
expiration of the initial IHA); and
     The request for renewal must include the following:

[[Page 61572]]

    (1) An explanation that the activities to be conducted under the 
requested renewal IHA are identical to the activities analyzed under 
the initial IHA, are a subset of the activities, or include changes so 
minor (e.g., reduction in pile size) that the changes do not affect the 
previous analyses, mitigation and monitoring requirements, or take 
estimates (with the exception of reducing the type or amount of take); 
and
    (2) A preliminary monitoring report showing the results of the 
required monitoring to date and an explanation showing that the 
monitoring results do not indicate impacts of a scale or nature not 
previously analyzed or authorized.
    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: September 1, 2023.
Kimberly Damon-Randall,
Director, Office of Protected Resources, National Marine Fisheries 
Service.
[FR Doc. 2023-19327 Filed 9-6-23; 8:45 am]
BILLING CODE 3510-22-P