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Notice2026-06394

Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to U.S. Coast Guard Fast Response Cutter Homeporting in Sitka, Alaska

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Published

April 2, 2026

Issuing agencies

Commerce DepartmentNational Oceanic and Atmospheric Administration

Abstract

NMFS has received a request from the U.S. Coast Guard (USCG) to modify an incidental harassment authorization (IHA) that was issued to the USCG on December 20, 2024, and effective from September 1, 2026, through August 31, 2027, to take small numbers of nine species of marine mammals, by Level A and Level B harassment, incidental to the construction activities associated with fast response cutter (FRC) homeporting in Sitka, Alaska. Pursuant to the Marine Mammal Protection Act (MMPA), NMFS is requesting comments on its proposal to modify the IHA. This modification includes changes to the duration, project design, and take estimates. NMFS will consider public comments prior to making any final decision on the issuance of the requested modification of the MMPA authorization and agency responses will be summarized in the final notice of our decision.

Full Text

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<title>Federal Register, Volume 91 Issue 63 (Thursday, April 2, 2026)</title>
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[Federal Register Volume 91, Number 63 (Thursday, April 2, 2026)]
[Notices]
[Pages 16672-16683]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2026-06394]

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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

[RTID 0648-XF546]

Takes of Marine Mammals Incidental to Specified Activities;
Taking Marine Mammals Incidental to U.S. Coast Guard Fast Response
Cutter Homeporting in Sitka, Alaska

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

ACTION: Notice; proposed modification of an incidental harassment
authorization; request for comments.

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SUMMARY: NMFS has received a request from the U.S. Coast Guard (USCG)
to modify an incidental harassment authorization (IHA) that was issued
to the USCG on December 20, 2024, and effective from September 1, 2026,
through August 31, 2027, to take small numbers of nine species of
marine mammals, by Level A and Level B harassment, incidental to the
construction activities associated with fast response cutter (FRC)
homeporting in Sitka, Alaska. Pursuant to the Marine Mammal Protection
Act (MMPA), NMFS is requesting comments on its proposal to modify the
IHA. This modification includes changes to the duration, project
design, and take estimates. NMFS will consider public comments prior to
making any final decision on the issuance of the requested modification
of the MMPA authorization and agency responses will be summarized in
the final notice of our decision.

DATES: Comments and information must be received no later than April
17, 2026.

ADDRESSES: Comments should be addressed to Permits and Conservation
Division, Office of Protected Resources, National Marine Fisheries
Service and should be submitted via email to <a href="/cdn-cgi/l/email-protection#541d00047a37383122313a27203d3a31143a3b35357a333b22"><span class="__cf_email__" data-cfemail="b1f8e5e19fd2ddd4c7d4dfc2c5d8dfd4f1dfded0d09fd6dec7">[email&#160;protected]</span></a>.
Electronic copies of the application and supporting documents, as well
as a list of the references cited in this document, may be obtained
online at: <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities">https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities</a>. In
case of problems accessing these documents, please call the contact
listed below.
Instructions: NMFS is not responsible for comments sent by any
other method, 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 <a href="https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act">https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act</a> without change. All personal identifying
information (e.g., name, address) voluntarily submitted by the
commenter may be publicly accessible. Do not submit confidential
business information or otherwise sensitive or protected information.

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

SUPPLEMENTARY INFORMATION:

Background

The MMPA prohibits the ``take'' of marine mammals, with certain
exceptions. Section 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 et
seq.) directs the Secretary of Commerce (as delegated to NMFS) to
allow, upon request, the incidental, but not intentional, taking of
small numbers of marine mammals by U.S. citizens who engage in a
specified activity (other than commercial fishing) within a specified
geographical region if certain findings are made and either regulations
are proposed or, if the taking is limited to harassment, a notice of a
proposed IHA is provided to the public for review.
Authorization for incidental takings shall be granted if NMFS finds
that the taking will have a negligible impact on the species or
stock(s) and will not have an unmitigable adverse impact on the
availability of the species or stock(s) for taking for subsistence uses
(where relevant). Further, NMFS must prescribe the permissible methods
of taking; 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 as ``mitigation'');
and requirements pertaining to the monitoring and reporting of the
takings. The definitions of all applicable MMPA statutory terms used
above are included in the relevant sections below (see also 16 U.S.C.
1362; 50 CFR 216.3, 216.103).

National Environmental Policy Act

To comply with the National Environmental Policy Act of 1969 (NEPA)
(42 U.S.C. 4321 et seq.) and NOAA Administrative Order (NAO) 216-6A,
NMFS must review our proposed action (i.e., the issuance of a modified
IHA) with respect to potential impacts on the human environment.
This action is consistent with categories of activities identified
in Categorical Exclusion B4 (IHAs with no anticipated serious injury or
mortality) of the Companion Manual for NAO 216-6A, which do not
individually or cumulatively have the potential for significant impacts
on the quality of the human environment and for which we have not
identified any extraordinary circumstances that would preclude this
categorical exclusion. Accordingly, NMFS determined that the issuance
of the initial IHA qualified to be categorically excluded from further
NEPA review. NMFS has preliminarily determined that application of this
categorical exclusion remains appropriate for this IHA modification.

History of Request

On January 19, 2024, NMFS received a request from the USCG for two
IHAs to take marine mammals incidental to pile driving (installation
and removal) associated with construction of two FRC homeporting docks
in Seward and Sitka, Alaska. On August 26, 2024, NMFS published a
Federal Register notice for the proposed IHAs (89 FR 60359). On
December 20, 2024, NMFS published a Federal Register notice announcing
the issuance of the IHAs to the USCG, one for Moorings Sitka effective
from September 1, 2026, through August 31, 2027, and one for Moorings
Seward effective from March 1, 2027, through February 29, 2028 (89 FR
104090).
On January 7, 2026, NMFS received a request from the USCG to modify
the IHA for Moorings Sitka. Following NMFS' review of the request, USCG
submitted a revised version on January 21, 2026, and an accompanying
marine mammal monitoring plan on February 19, 2026, which NMFS
determined to be adequate and complete on March 2, 2026. In the
original IHA issued to the USCG for Moorings Sitka, NMFS authorized
take of 9 species (14 stocks) of marine mammal by Level B harassment
and, for a subset of those species, by Level A harassment (3 species (4
stocks)).
The modification was requested due to changes in project design
(including

[[Page 16673]]

the use of different pile types and sizes), which resulted in changes
to the ensonified areas and estimates of take by Level A and Level B
harassment. The USCG also revised some of their proposed mitigation and
monitoring measures.

Description of Proposed Activity

Overview

The USCG proposes to demolish and construct shore-side facilities
at Moorings Sitka in Sitka Harbor, Alaska, to support a second FRC. The
project is needed to provide adequate vessel berthing capability to
support modern USCG cutters and ultimately, readiness as part of the
USCG's overall mission. The USCG proposes to use impact, down-the-hole
(DTH), and vibratory pile driving to install and remove piles,
including steel and timber piles. These methods of pile driving will
introduce underwater sounds that may result in take, by Level A and
Level B harassment, of marine mammals. Pile removal may occur by
vibratory, cutting, or clipping methods. Cutting and clipping are not
anticipated to have the potential to result in incidental take of
marine mammals because they are either above water, do not last for
sufficient duration to present the reasonable potential for disruption
of behavioral patterns, do not produce sound levels with likely
potential to result in marine mammal harassment, or some combination of
the above.

Dates and Duration

The proposed modified IHA would be valid for the statutory maximum
of 1 year from the date of effectiveness. It would become effective
upon written notification from the applicant to NMFS but not beginning
later than 1 year from the date of issuance or extending beyond 2 years
from the date of issuance. Pile removal and installation activities at
Moorings Sitka would occur for a total of approximately 113 non-
consecutive days; however, project delays may occur due to a number of
factors, including availability of equipment and/or materials, weather-
related delays, equipment maintenance and/or repair, and other
contingencies.

Specific Geographic Region

There are no changes to the specific geographic region of Moorings
Sitka described in the Federal Register notice for the proposed IHA (89
FR 60359, July 25, 2024). Therefore, a detailed description is not
provided here. Please refer to that Federal Register notice for the
description of the specific geographic region.

Detailed Description of the Specified Activity

At Moorings Sitka, removal of existing mooring dolphins and float,
owned by the City of Sitka, would be required to allow for construction
of a new sea-going buoy tender (hereafter WLB) pier and FRC floating
dock. The planned pile extraction and installation activities from the
initial IHA compared to the proposed modification are shown in table 1.
Due to misidentification of pile types and sizes in the initial request
for an IHA, the USCG modified their project design. The USCG still
proposes to remove an existing mooring dolphin at the existing pier;
however, instead of removing up to four concrete piles with vibratory
extraction, three 24-inch (60.96 centimeter (cm)) dolphin piles, which
are held in place with rock anchors, would be removed, along with one
24-inch (60.96 cm) steel camel pile, by vibratory extraction (table 2).
Instead of installing a new mooring dolphin with three 30-inch (76.2
cm) concrete piles, the USCG would install a new mooring dolphin with
four 24-inch (60.96 cm) steel piles by vibratory, impact, and DTH
drilling methods (tables 2 and 3). The USCG would still remove the
existing city-owned float with six 14-inch (35.56 cm) timber guide
piles via vibratory extraction (table 2).
Construction of the new WLB pier would no longer include
installation of 105 30-inch (76.2 cm) concrete structure piles and 54
13-inch (33.02 cm) plastic piles; instead, 95 24-inch (60.96 cm) steel
piles would be installed using vibratory and impact driving and up to
25 piles would be further installed using DTH drilling methods (tables
2 and 3). This would require temporary installation and removal of 12
24-inch (60.96 cm) template piles using a vibratory hammer (table 2).
In addition, the new WLB pier would require installation of 60 16-inch
(40.64 cm) steel fender piles via vibratory driving (table 2).
The USCG still proposes to install a new FRC floating dock;
however, the dock would now be supported by 8 24-inch (60.96 cm) steel
piles which would be installed using vibratory, impact, and DTH
drilling methods (tables 2 and 3).

Table 1--Pile Extraction and Installation Information From the Initial IHA Compared to the Modification Request
----------------------------------------------------------------------------------------------------------------
Pile diameter and type Methods from Modified pile Modified
Project component from initial IHA initial IHA diameter and type methods
----------------------------------------------------------------------------------------------------------------
Float Demolition............. 12-inch timber.......... Vibratory 14-inch timber....... Vibratory
extraction. extraction.
Dolphin Demolition........... 30-inch concrete........ Vibratory 24-inch steel........ Vibratory
extraction. extraction.
Dolphin Installation......... 30-inch concrete........ Vibratory 24-inch steel........ Vibratory
installation, installation,
impact, DTH impact, DTH
anchor. anchor.
WLB Pier Guide............... 14-inch timber.......... Vibratory 24-inch steel........ Vibratory
installation. installation.
WLB Pier Fender.............. 13-inch plastic......... Vibratory 16-inch steel........ Vibratory
installation. installation.
WLB Pier Support............. 30-inch concrete........ Vibratory 24-inch steel........ Vibratory
installation, installation,
impact, DTH impact, DTH
anchor. anchor.
FRC Dock..................... 30-inch concrete........ Vibratory 24-inch steel........ Vibratory
installation, installation,
impact, DTH impact, DTH
anchor. anchor.
WLB Pier Template............ ........................ ............... 24-inch steel........ Vibratory
installation.
----------------------------------------------------------------------------------------------------------------

Table 2--Vibratory Pile Removal and Installation Pile Size/Type, Number, and Duration
--------------------------------------------------------------------------------------------------------------------------------------------------------
Estimated
Pile size and material Activity Number of Duration per Piles per day Maximum piles duration
piles pile (minutes) per day (days)
--------------------------------------------------------------------------------------------------------------------------------------------------------
24-inch steel............................. Extraction of existing pile. 4 30 4 4 1
14-inch timber............................ Extraction of existing pile. 6 30 5 5 2

[[Page 16674]]

24-inch steel............................. Installation of template 12 15 4 4 3
pile.
24-inch steel............................. Extraction of template pile. 12 15 4 4 3
24-inch steel............................. Installation of support pile 95 75 3 6 32
24-inch steel............................. Installation of dolphin pile 4 75 1 3 4
24-inch steel............................. Installation of guide pile.. 8 75 2 4 4
16-inch steel............................. Installation of fender pile. 60 30 5 8 12
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: USCG used the number of piles per day to calculate the total number of project days while the maximum number of piles per day was used to
calculate the Level A harassment isopleths.

Table 3--Impact and DTH Pile Installation Pile Size/Type, Number, and Duration
--------------------------------------------------------------------------------------------------------------------------------------------------------
Strikes per Duration
Number of Strikes per second of DTH (minutes) of Piles Maximum Estimated
Pile size and material Activity piles pile of impact drilling per DTH drilling driven piles per duration
driving pile per pile per day day (days)
--------------------------------------------------------------------------------------------------------------------------------------------------------
24-inch steel...................... Impact installation 95 500 N/A N/A 4 8 24
of support pile.
24-inch steel...................... Impact installation 4 500 N/A N/A 1 3 4
of dolphin pile.
24-inch steel...................... Impact installation 8 500 N/A N/A 3 6 3
of guide pile.
24-inch steel...................... DTH installation of 25 N/A 12.3 120 2 4 13
support pile.
24-inch steel...................... DTH installation of 4 N/A 12.3 120 1 3 4
dolphin pile.
24-inch steel...................... DTH installation of 8 N/A 12.3 120 2 4 4
guide pile.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: N/A = Not Applicable. USCG used the number of piles per day to calculate the total number of project days while the maximum number of piles per
day was used to calculate the Level A harassment isopleths.

Proposed mitigation, monitoring, and reporting measures are
described in detail later in this document (please see Proposed
Mitigation and Proposed Monitoring and Reporting).

Description of Marine Mammals in the Area of Specified Activities

A detailed description of the species likely to be affected by the
USCG project, including brief introductions to the species and relevant
stocks as well as available information regarding population trends and
threats, and information regarding local occurrence, were provided in
the Federal Register notice for the proposed IHA (89 FR 60359, July 25,
2024) and an updated description of marine mammal hearing was included
in the notice of the final IHA (89 FR 104090, December 20, 2024); since
that time, we are not aware of any changes in the status of these
species and stocks; therefore, detailed descriptions are not provided
here. Please refer to that Federal Register notices for these
descriptions. NMFS has reviewed the draft 2024 Stock Assessment Reports
for Alaska and the Pacific, information on relevant Unusual Mortality
Events, and recent scientific literature, and found no new information
that changes the information provided in the Federal Register notices
of the proposed and final IHA. Please also refer to NMFS' website
(<a href="https://www.fisheries.noaa.gov/find-species">https://www.fisheries.noaa.gov/find-species</a>) for generalized species
accounts.
We have preliminarily determined that no new information affects
our original analysis of impacts under the initial IHA. However, the
USCG is no longer requesting take by Level B harassment of northern fur
seal. While take of northern fur seals (Callorhinus ursinus) by Level B
harassment was authorized in the initial IHA, the USCG indicated the
species has not been observed in the region since 2023 and are
considered to be `rare' in the area based on observational data;
therefore, the USCG no longer requests take of northern fur seals.
Table 4 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 mortality and serious injury (M/
SI) from anthropogenic sources are included here as gross indicators of
the status of the species or stocks and other threats.

Table 4--Species, Stocks, and the Status of Marine Mammals \1\ With Estimated Take From the Specified Activities
--------------------------------------------------------------------------------------------------------------------------------------------------------
ESA/MMPA status; Stock abundance (CV,
Common name Scientific name Stock strategic (Y/N) Nmin, most recent PBR Annual M/
\2\ abundance survey) \3\ SI\4\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Order Artiodactyla--Cetacea--Mysticeti (baleen whales)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Eschrichtiidae:
Gray Whale...................... Eschrichtius robustus.. Eastern N Pacific...... -, -, N 26,960 (0.05, 25,849, 801 131
2016).
Fin Whale....................... Balaenoptera physalus.. Northeast Pacific...... E, D, Y UND (UND, UND, 2013).. UND 0.6
Humpback Whale.................. Megaptera novaeangliae. Hawai'i................ -, -, N 11,278 (0.56, 7,265, 127 27.09
2020).
Humpback Whale.................. Megaptera novaeangliae. Mexico-North Pacific... T, D, Y N/A (N/A, N/A, 2006).. UND 0.57

[[Page 16675]]

Minke Whale..................... Balaenoptera Alaska................. -, -, N N/A (N/A, N/A, N/A)... UND 0
acutorostrata.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Odontoceti (toothed whales, dolphins, and porpoises)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Delphinidae:
Killer Whale.................... Orcinus orca........... Eastern North Pacific -, -, N 1,920 (N/A, 1,920, 19 1.3
Alaska Resident. 2019).
Killer Whale.................... Orcinus orca........... Eastern North Pacific -, -, N 587 (N/A, 587, 2012).. 5.9 0.8
Gulf of Alaska,
Aleutian Islands and
Bering Sea Transient.
Killer Whale.................... Orcinus orca........... Eastern North Pacific -, -, N 302 (N/A, 302, 2018).. 2.2 0.2
Northern Resident.
Killer Whale.................... Orcinus orca........... West Coast Transient... -, -, N 349 (N/A, 349, 2018).. 3.5 0.4
Family Phocoenidae (porpoises):
Dall's Porpoise................. Phocoenoides dalli..... Alaska................. -, -, N UND (UND, UND, 2015).. UND 37
Harbor Porpoise................. Phocoena phocoena...... Yakutat/Southeast -, -, N N/A (N/A, N/A, 1997).. UND 22.2
Alaska Offshore Waters.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Order Carnivora--Pinnipedia
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Otariidae (eared seals and
sea lions):
Steller Sea Lion................ Eumetopias jubatus..... Western................ E, D, Y 49,837 (N/A, 49,837, 299 267
2022).
Steller Sea Lion................ Eumetopias jubatus..... Eastern................ -, -, N 36,308 (N/A, 36,308, 2,178 93.2
2022).
Family Phocidae (earless seals):
Harbor Seal..................... Phoca vitulina......... Sitka/Chatham Strait... -, -, N 13,289 (N/A, 11,883, 356 77
2015).
--------------------------------------------------------------------------------------------------------------------------------------------------------
\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
(<a href="https://marinemammalscience.org/science-and-publications/list-marine-mammal-species-subspecies/">https://marinemammalscience.org/science-and-publications/list-marine-mammal-species-subspecies/</a>).
\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: <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports-region">https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports-region</a>. CV is coefficient of variation; Nmin is the minimum estimate of stock abundance.
\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.

Potential Effects of Specified Activities on Marine Mammals and Their
Habitat

The effects of underwater noise from the USCG's construction
activities have the potential to result in harassment of marine mammals
in the vicinity of the project areas. The notice of proposed IHA (89 FR
60359, July 25, 2024) included a discussion of the effects of
anthropogenic noise on marine mammals and the potential effects of
underwater noise from the USCG's construction activities on marine
mammals and their habitat. That information and analysis is referenced
in this proposed IHA modification and is not repeated here; please
refer to the notice of proposed IHA (89 FR 60359, July 25, 2024).

Estimated Take of Marine Mammals

This section provides an estimate of the number of incidental takes
proposed for authorization through the IHA, which will inform NMFS'
consideration of ``small numbers,'' the negligible impact
determinations, and impacts on subsistence uses.
Harassment is the only type of take expected to result from these
activities. A description of the acoustic criteria and descriptions of
Level B harassment and Level A harassment were included in the notice
of proposed IHA (89 FR 60359, July 25, 2024). That information and
analysis is referenced in this proposed IHA modification and is not
repeated here; please refer to the notice of proposed IHA (89 FR 60359,
July 25, 2024).

Ensonified Area

Here, we describe operational and environmental parameters of the
proposed modified activity that are used in estimating the area
ensonified above the acoustic thresholds described in the 2024 Updated
Technical Guidance for Assessing the Effects of Anthropogenic Sound on
Marine Mammal Hearing (hereafter Updated Technical Guidance) (NMFS,
2024), 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 project. Marine
mammals are expected to be affected via sound generated by the primary
components of the project (i.e., impact pile driving, vibratory pile
driving, vibratory pile removal, and DTH).
In order to calculate distances to the Level A harassment and Level
B harassment thresholds for the methods and piles proposed for this
project (tables 2 and 3), NMFS used acoustic monitoring data from other
locations to develop proxy source levels for the various pile types,
sizes, and methods (table 5).

[[Page 16676]]

Table 5--Sound Source Levels
----------------------------------------------------------------------------------------------------------------
SELsingle-
Peak (dB re 1 RMS (dB re 1 strike (dB re
Pile size and material Activity [micro]Pa at [micro]Pa at 1 [mu]Pa\2\s Reference
10 m) 10 m) at 10 m)
----------------------------------------------------------------------------------------------------------------
14-inch timber............... Vibratory....... N/A 162 N/A Caltrans
(2020).
16-inch steel................ Vibratory....... N/A 163 N/A NMFS (2023).
24-inch steel................ Vibratory....... N/A 163 N/A NMFS (2023).
24-inch steel................ Impact driving.. 203 190 177 Caltrans
(2015).
24-inch steel................ DTH drilling.... 184 167 159 Heyvaert and
Reyff (2021).
----------------------------------------------------------------------------------------------------------------
Note: N/A = Not Applicable, m = meters.

NMFS recommends treating DTH systems as both impulsive and
continuous, non-impulsive sound source types simultaneously. Thus,
impulsive thresholds are used to evaluate Level A harassment, and
continuous thresholds are used to evaluate Level B harassment. With
regards to DTH mono-hammers, NMFS recommends proxy levels for Level A
harassment based on available data regarding DTH systems of similar
sized piles and holes.
DTH systems operate as a rotating drill head with an attached
hammer that fractures bedrock on each rotation. The strike rate (in
strikes per second) is directly related to the speed of the drill
rotation. Measurements of DTH drilling taken primarily in southeast
Alaska have recorded a range of strike rates for 24-inch (60.96 cm)
diameter holes between 9 and 15.5 strikes per second, with an average
of approximately 12.3 strikes per second (Heyvaert and Reyff, 2021;
Denes et al., 2016, Miner et al., 2023, Illingworth and Rodkin, 2023;
Reyff et al., 2025). While USCG proposed a rate of 15 strikes per
second in their modification request, this value is at the high end of
measured rates, which increases the ensonified areas relative to lower
strike rates, potentially producing overly-conservative isopleths. NMFS
instead proposes the average of the measured values for this pile size,
and has used 12.3 strikes per second in our calculations.
Level B Harassment Zones
Transmission loss (TL) is the decrease in acoustic intensity as an
acoustic pressure wave propagates out from a source. TL parameters vary
with frequency, temperature, sea conditions, current, source and
receiver depth, water depth, water chemistry, and bottom composition
and topography. The general formula for underwater TL is:

TL = B * log<INF>10</INF> (R<INF>1</INF>/R<INF>2</INF>),

Where:

TL = transmission loss in dB,
B = transmission loss coefficient; for practical spreading equals
15,
R<INF>1</INF> = the distance of the modeled SPL from the driven
pile, and
R<INF>2</INF> = the distance from the driven pile of the initial
measurement.

The recommended TL coefficient for most nearshore environments is
the practical spreading value of 15. This value results in an expected
propagation environment that would lie between spherical and
cylindrical spreading loss conditions, which is the most appropriate
assumption for the USCG's proposed activities. The Level B harassment
zones and approximate amount of area ensonified for the proposed
underwater activities are shown in table 6.
Level A Harassment Zones
The ensonified area associated with Level A harassment is more
technically challenging to predict due to the need to account for a
duration component. Therefore, NMFS developed an optional User
Spreadsheet tool to accompany the 2024 Updated Technical Guidance that
can be used to relatively simply predict an isopleth distance for use
in conjunction with marine mammal density or occurrence to help predict
potential takes. We note that because of some of the assumptions
included in the methods underlying this optional tool, we anticipate
that the resulting isopleth estimates are typically going to be
overestimates of some degree, which may result in an overestimate of
potential take by Level A harassment. However, this optional tool
offers a practical, alternative way to estimate isopleth distances when
more sophisticated modeling methods are not available or practical. For
stationary sources such as 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 AUD INJ. Inputs used in the optional User Spreadsheet tool
include values in tables 2 and 3 (e.g., number of piles per day,
duration and/or strikes per pile), and table 5 (i.e., source levels),
and the resulting estimated isopleths are reported in table 6.

Table 6--Projected Distances to Level A and Level B Harassment Isopleths by Marine Mammal Hearing Group
--------------------------------------------------------------------------------------------------------------------------------------------------------
Distance to
Distance to Distance to Level A (m) Distance to Distance to Total Level
Level A (m) Level A (m) for very Level A (m) Level A (m) Distance to B
Pile size and material Activity for low- for high- high for phocids for Level B (m) ensonified
frequency frequency frequency in water otariids in area
cetaceans cetaceans cetaceans water (km\2\)
--------------------------------------------------------------------------------------------------------------------------------------------------------
24-inch steel....................... Vibratory extraction of 19.9 7.6 16.3 25.6 8.6 7,356.4 7.674
existing pile.
14-inch timber...................... Vibratory extraction of 19.8 7.6 16.2 25.5 8.6 6,309.6 6.409
existing pile.
24-inch steel....................... Vibratory installation 12.5 4.8 10.2 16.1 5.4 7,356.4 7.674
of template pile.
24-inch steel....................... Vibratory extraction of 12.5 4.8 10.2 16.1 5.4 7,356.4 7.674
template pile.
24-inch steel....................... Vibratory installation 48 18.5 39.2 61.8 20.8 7,356.4 7.674
of support pile.
24-inch steel....................... Vibratory installation 30.3 11.6 24.7 39 13.1 7,356.4 7.674
of dolphin pile.
24-inch steel....................... Vibratory installation 36.7 14.1 29.9 47.2 15.9 7,356.4 7.674
of guide pile.
16-inch steel....................... Vibratory installation 31.6 12.1 25.8 40.7 13.7 7,356.4 7.674
of fender pile.
24-inch steel....................... Impact installation of 998.2 127.4 1,544.6 886.7 330.5 1,000 0.562
support pile.
24-inch steel....................... Impact installation of 519.1 66.2 803.2 461.1 171.9 1,000 0.562
dolphin pile.
24-inch steel....................... Impact installation of 824 105.1 1,275.1 732 272.8 1,000 0.562
guide pile.

[[Page 16677]]

24-inch steel....................... DTH installation of 1,251.3 159.6 1,936.4 1,111.6 414.4 13,593.6 13.716
support pile.
24-inch steel....................... DTH installation of 1,032.9 131.8 1,598.4 917.6 342 13,593.6 13.716
dolphin pile.
24-inch steel....................... DTH installation of 1,251.3 159.6 1,936.4 1,111.6 414.4 13,593.6 13.716
guide pile.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: m = meters. Distances refer to the maximum radius of the isopleth; the actual isopleth may be truncated by landforms. The values provided for
distance of the Level A harassment isopleth represent the distance at which an animal may incur auditory injury (AUD INJ) if that animal remained at
that distance for the entire duration of the activity within a 24-hour period.

For a given activity, Level A harassment zones are typically
smaller than Level B harassment zones. However, in rare cases, the
maximum calculated distance to the Level A harassment threshold is
greater than the maximum calculated distance to the Level B harassment
threshold (e.g., values for impact pile driving of 24-inch steel
support and guide piles for very high-frequency (VHF) cetaceans) (table
6). Calculations of Level A harassment isopleths include a duration
component that, in the case of impact pile driving and DTH methods, is
estimated through the total number of expected daily strikes within a
24-hour period and the associated pulse duration. When analyzing
potential acoustic impacts for a stationary sound source such as impact
pile driving or DTH, we assume that an animal would be exposed to all
of the strikes expected for that activity within that 24-hour period.
In contrast, calculation of Level B harassment isopleths does not
include a duration component. Due to differences in the parameters that
characterize each form of harassment, it is assumed that Level B
harassment occurs instantaneously rather than building through exposure
to a series of hammer strikes over a longer duration. Thus, depending
on the duration included in the calculation, the calculated radii to
Level A harassment isopleths can be larger than the calculated radii to
the Level B harassment isopleth for the same activity.

Marine Mammal Occurrence

In this section we provide information about the occurrence of
marine mammals, including relevant information which will inform the
take calculations. Available information regarding marine mammal
occurrence in the project area includes monitoring data, prior
incidental take authorizations, and ESA consultations on previous
projects. The USCG modified their take request for Dall's porpoise,
relying on occurrence information rather than density data to estimate
take at Moorings Sitka, the latter of which was used to estimate take
for the initial IHA. There are no other changes to the marine mammal
occurrence and group size described in the Federal Register notice for
the proposed IHA (89 FR 60359, July 25, 2024). Therefore, a detailed
description of occurrence and group size are not provided here. Daily
occurrence probability of each marine mammal species is based on
consultation with previous monitoring reports, local researchers, and
marine professionals. Occurrence probability estimates are based on
conservative density approximations for each species and factor in
historic data of occurrence, seasonality, and group size in Sitka Sound
and Sitka Channel. A summary of occurrence is shown in table 7. Group
size is based on the best available published research for these
species and their presence in the project areas.

Table 7--Estimated Species Occurrence at Moorings Sitka
------------------------------------------------------------------------
Occurrence frequency
Species Group (group size per time
size period)
------------------------------------------------------------------------
Steller sea lion..................... 2 1-2 per day.
Harbor seal.......................... 2 1-2 per day.
Killer whale......................... 7 4 per month.
Harbor porpoise...................... 5 4 per month.
Dall's porpoise...................... 6 2 per month.
Humpback whale....................... 4 4 per month.
Gray whale........................... 4 2 per month.
Minke whale.......................... 4 2 per month.
------------------------------------------------------------------------

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.
Estimated occurrence of species in the initial IHA did not change
but were converted to the number of groups per day or per month (i.e.,
species whose occurrence was one group per week is now four groups per
month). When the group size estimated in the initial IHA was used in
the updated take calculations, the group size was rounded up to the
next full individual (e.g., minke whales had an occurrence estimate of
one group of 3.5 individuals per 2 weeks). In the updated take
estimates, this becomes two groups of four individuals per month.
To calculate take by Level A harassment, the expected occurrence
(group size and estimated frequency) was multiplied by the number of
days that the Level A harassment isopleth exceeded the proposed
shutdown zone. Level A take is thus proposed for VHF cetaceans, phocids
(PW), and otariids (OW) for all 52 days of proposed impact pile driving
and DTH drilling.
The following equations were used to estimate take by Level A
harassment:

Monthly estimated take = estimated monthly frequency x group size x
(days of pile driving activity/30 days per month)
Daily estimated take = estimated daily frequency x group size x days of
pile driving activity

To calculate take by Level B harassment, the expected occurrence
(group size and estimated frequency) was multiplied by the total number
of days of pile driving. For species where take by Level A harassment
is requested, the estimated take by Level A harassment was subtracted
from the takes by Level B harassment.
The following equations were used to estimate take by Level B
harassment:

Monthly estimated take = estimated monthly frequency x group size x
(days of pile driving activity/30 days per month)-Level A take
Daily estimated take = estimated daily frequency x group size x days of
pile driving activity-Level A take

Table 8 summarizes proposed amounts of take by both Level A and
Level B harassment, as well as the percentage of each stock expected to
be taken, from the modified activities.

[[Page 16678]]

Table 8--Estimated Take of Marine Mammals From the Specified Activities
--------------------------------------------------------------------------------------------------------------------------------------------------------
Instances of
Level A Level B take as a
Species Stock harassment harassment SAR abundance percentage of
population
--------------------------------------------------------------------------------------------------------------------------------------------------------
Steller sea lion............................... Western................................ 2 8 49,837 <1
Steller sea lion............................... Eastern................................ 102 340 36,308 <1
Harbor seal.................................... Sitka/Chatham Strait................... 104 348 13,289 3.4
Killer whale *................................. Eastern North Pacific Alaska Resident.. 0 64 1,920 3.3
Killer whale *................................. Eastern North Pacific Gulf of Alaska, 0 20 587 3.4
Aleutian Islands and Bering Sea
Transient.
Killer whale *................................. Eastern North Pacific Northern Resident 0 10 302 3.3
Killer whale *................................. West Coast Transient................... 0 12 349 3.4
Harbor porpoise................................ Yakutat/Southeast Alaska Offshore 35 41 N/A N/A
Waters.
Dall's porpoise................................ Alaska................................. 21 25 UND UND
Humpback whale................................. Hawai[revaps]i......................... 0 60 11,278 <1
Humpback whale................................. Mexico-North Pacific................... 0 1 N/A <1
Gray whale..................................... Eastern North Pacific.................. 0 31 26,960 <1
Minke whale.................................... Alaska................................. 0 31 N/A N/A
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: N/A = Not Applicable; UND = Undetermined; Steller sea lion stock attribution: 97.8 percent Eastern DPS and 2.2 percent Western DPS; Humpback whale
stock attribution: 98 percent Hawai[revaps]i and 2 percent Mexico-North Pacific.
* Percent of stock impacted for killer whales was estimated assuming each stock is taken in proportion to its population size from the total take. The
Alaska Resident, Gulf of Alaska, Northern Resident, and West Coast Transient stocks are expected at Moorings Sitka, and the Alaska Resident stock
represents approximately 60 percent of the available animals, the Gulf of Alaska stock represents approximately 19 percent, the Northern Resident
stock represents approximately 10 percent, and the West Coast Transient represents approximately 11 percent. Takes were then calculated based on the
proportional representation of available stocks, which results in 64 Level B harassment takes of the Alaska Resident stock, 20 Level B harassment
takes of the Gulf of Alaska stock, 10 Level B harassment takes of the Northern Resident stock, and 12 Level B harassment takes of the West Coast
Transient stock.

Proposed Mitigation

In order to issue an IHA under section 101(a)(5)(D) of the MMPA,
NMFS must set forth the permissible methods of taking pursuant to the
activity, and other means of effecting the least practicable impact on
the species or stock and its habitat, paying particular attention to
rookeries, mating grounds, and areas of similar significance, and on
the availability of the species or stock for taking for certain
subsistence uses. 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, as
well as subsistence uses. 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.
The mitigation requirements described in the following were
proposed by the USCG in its adequate and complete request for IHA
modification or are the result of subsequent coordination between NMFS
and the USCG. The USCG has agreed that all of the mitigation measures
are practicable. NMFS has fully reviewed the specified activities and
the mitigation measures to determine if the mitigation measures would
result in the least practicable adverse impact on marine mammals and
their habitat, as required by the MMPA, and has determined the proposed
measures are appropriate. NMFS describes these below as proposed
mitigation requirements and has included them in the proposed IHA
modification.
The USCG must:
<bullet> Ensure that construction supervisors and crews, the
monitoring team, and relevant USCG staff are trained prior to the start
of all pile driving and DTH activity, so that responsibilities,
communication procedures, monitoring protocols, and operational
procedures are clearly understood. New personnel joining during the
project must be trained prior to commencing work;
<bullet> Employ three to six PSOs and establish monitoring
locations as described in the Marine Mammal Monitoring Plan (hereafter
Monitoring Plan) and the IHA. The USCG must monitor the project area to
the maximum extent possible based on the required number of PSOs,
required monitoring locations, and environmental conditions. For all
pile driving and removal at least one PSO must be used. The PSO will be
stationed as close to the activity as possible;
<bullet> The placement of the PSOs during all pile driving and
removal and DTH activities will ensure that the entire shutdown zone is
visible during pile installation;
<bullet> Monitoring must take place from 30 minutes prior to
initiation of pile driving or DTH activity (i.e., pre-activity
monitoring) through 30 minutes post-activity of pile driving or DTH
activity;
<bullet> Pre-activity monitoring must be conducted during periods
of visibility sufficient for the lead PSO to determine that the
shutdown zones indicated in table 9 are clear of marine mammals. Pile
driving and DTH may commence following 30 minutes of observation when
the determination is made that the shutdown zones are clear of marine
mammals;
<bullet> The USCG must use soft start techniques when impact pile
driving. Soft start requires contractors to provide an initial set of
three strikes at reduced

[[Page 16679]]

energy, followed by a 30-second waiting period, then two subsequent
reduced energy strike sets. A soft start must be implemented at the
start of each day's impact pile driving and at any time following
cessation of impact pile driving for a period of 30 minutes or longer;
and
<bullet> If a marine mammal is observed entering or within the
shutdown zones indicated in table 9, pile driving and DTH must be
delayed or halted. If pile driving is delayed or halted due to the
presence of a marine mammal, the activity may not commence or resume
until either the animal has voluntarily exited and been visually
confirmed beyond the shutdown zone (table 9) or 15 minutes have passed
without re-detection of the animal.
In their modification request, the USCG stated the shutdown zones
outlined in the initial IHA for pinnipeds are no longer feasible for
the modified project. On the opposite side of the channel there are two
seafood processing plants that are roughly 210 m and 450 m from the
project location. These facilities, which can attract pinnipeds, are
within the estimated Level A harassment isopleths for impact and DTH
activities for both pinniped hearing groups, and marine mammals near
these facilities are likely to lead to delays to the start of
construction as well as an increased number of shutdowns. The USCG
requested to use a minimum 10-m shutdown zone for all activities rather
than the 30-m minimum shutdown zone described in the issued IHA.
Further, the USCG indicated it is no longer practicable to have
vessel-based PSOs monitor the shutdown zones for DTH activity. Instead,
PSOs will be land-based and stationed at up to six different locations
depending on the in-water activity (see the Proposed Monitoring and
Reporting section for more information).

Table 9--Proposed Shutdown and Monitoring Zones
--------------------------------------------------------------------------------------------------------------------------------------------------------
Minimum Minimum Minimum
shutdown shutdown shutdown Minimum Minimum Level B
Pile size and material Activity zone (m) zone (m) zone (m) shutdown shutdown harassment
for LF for HF for VHF zone (m) zone (m) monitoring zone
cetaceans cetaceans cetaceans for PW for OW (m)
--------------------------------------------------------------------------------------------------------------------------------------------------------
24-inch steel........................... Vibratory extraction of 20 10 20 30 10 7,360
existing pile.
14-inch timber.......................... Vibratory extraction of 20 10 20 30 10 6,310
existing pile.
24-inch steel........................... Vibratory installation of 15 10 15 20 10 7,360
template pile.
24-inch steel........................... Vibratory extraction of 15 10 15 20 10 7,360
template pile.
24-inch steel........................... Vibratory installation of 50 20 40 65 25 7,360
support pile.
24-inch steel........................... Vibratory installation of 35 15 25 40 15 7,360
dolphin pile.
24-inch steel........................... Vibratory installation of 40 15 30 50 20 7,360
guide pile.
16-inch steel........................... Vibratory installation of 35 15 30 45 15 7,360
fender pile.
24-inch steel........................... Impact installation of 1,000 130 100 100 100 1,000
support pile. (VHF: 1,545 *)
24-inch steel........................... Impact installation of 520 70 100 100 100 1,000
dolphin pile.
24-inch steel........................... Impact installation of 830 110 100 100 100 1,000
guide pile. (VHF: 1,280 *)
24-inch steel........................... DTH installation of 1,255 160 100 100 100 13,600
support pile.
24-inch steel........................... DTH installation of 1,035 135 100 100 100 13,600
dolphin pile.
24-inch steel........................... DTH installation of guide 1,255 160 100 100 100 13,600
pile.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: m = meters. Distances (m) refer to the maximum radius of the Level A harassment and Level B harassment isopleths and is rounded. The actual zone
may be truncated by landforms. The values provided for calculated distances of the Level A harassment isopleth represent the distance at which an
animal may incur AUD INJ if that animal remained at that distance for the entire duration of the activity within a 24-hour period.
* For VHF cetaceans, the shutdown zone is larger than the monitoring zone; therefore, the extent of the shutdown zone is the monitoring zone for VHF
cetaceans during impact installation of piles.

NMFS conducted an independent evaluation of the proposed measures
and has preliminarily determined that the proposed mitigation measures
provide the means of effecting the least practicable impact on the
affected species or stocks and their habitat, paying particular
attention to rookeries, mating grounds, and areas of similar
significance.

Proposed Monitoring and Reporting

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

[[Page 16680]]

(hereafter Monitoring Plan) and/or are the result of subsequent
coordination between NMFS and the USCG. The USCG has agreed to the
requirements. NMFS describes these below as requirements and has
included them in the proposed IHA modification. Marine mammal
monitoring must be conducted in accordance with the Monitoring Plan
provided by the USCG for this proposed IHA modification and is
available at <a href="https://www.fisheries.noaa.gov/action/incidental-take-authorization-united-states-coast-guards-fast-response-cutter-homeporting">https://www.fisheries.noaa.gov/action/incidental-take-authorization-united-states-coast-guards-fast-response-cutter-homeporting</a>.

Visual Monitoring

Marine mammal monitoring must be conducted in accordance with the
conditions in this section and this IHA. Marine mammal monitoring
during pile driving activities would be conducted by up to six PSOs
meeting NMFS' standards and in a manner consistent with the following:
<bullet> PSOs must be independent of the activity contractor (e.g.,
employed by a subcontractor) and have no other assigned tasks during
monitoring periods;
<bullet> At least one PSO would have prior experience performing
the duties of a PSO during construction activity pursuant to a NMFS-
issued incidental take authorization;
<bullet> Other PSOs may substitute other relevant experience,
education (degree in biological science or related field), or training
for prior experience performing the duties of a PSO during construction
activity pursuant to a NMFS-issued incidental take authorization;
<bullet> 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;
<bullet> PSOs must be approved by NMFS prior to beginning any
activity subject to the IHA.
PSOs should have the following additional qualifications:
<bullet> Ability to conduct field observations and collect data
according to assigned protocols;
<bullet> Experience or training in the field identification of
marine mammals, including the identification of behaviors;
<bullet> Sufficient training, orientation, or experience with the
construction operation to provide for personal safety during
observations;
<bullet> Writing skills sufficient to prepare a report of
observations including but not limited to the number and species of
marine mammals observed; dates and times when in-water construction
activities were conducted; dates, times, and reason for implementation
of mitigation (or why mitigation was not implemented when required);
and marine mammal behavior; and
<bullet> Ability to communicate orally, by radio or in person, with
project personnel to provide real-time information on marine mammals
observed in the area as necessary.
For all pile driving activities, the USCG must establish the
monitoring locations as described in the Monitoring Plan. PSOs would be
equipped with high quality binoculars for monitoring and radios or
cells phones for maintaining contact with work crews. 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

A draft marine mammal monitoring report will be submitted to NMFS
within 90 days after the completion of pile driving and removal
activities for each IHA, or 60 days prior to a requested date of
issuance from any future IHAs for projects at the same location,
whichever comes first. The report will include an overall description
of work completed, a narrative regarding marine mammal sightings, and
associated PSO data sheets. Specifically, the report must include:
<bullet> Dates and times (begin and end) of all marine mammal
monitoring;
<bullet> Construction activities occurring during each daily
observation period, including the number and type of piles driven or
removed and by what method (i.e., impact, vibratory, DTH) and the total
equipment duration for vibratory removal for each pile or total number
of strikes for each pile (impact driving);
<bullet> PSO locations during marine mammal monitoring;
<bullet> Environmental conditions during monitoring periods (at
beginning and end of PSO shift and whenever conditions change
significantly), including Beaufort sea state and any other relevant
weather conditions including cloud cover, fog, sun glare, and overall
visibility to the horizon, and estimated observable distance;
<bullet> Upon observation of a marine mammal, the following
information:
[cir] Name of PSO who sighted the animal(s) and PSO location and
activity at the time of sighting;
[cir] Time of sighting;
[cir] Identification of the animal(s) (e.g., genus/species, lowest
possible taxonomic level, or unidentifiable), PSO confidence in
identification, and the composition of the group if there is a mix of
species;
[cir] Distance and bearing of each marine mammal observed relative
to the pile being driven for each sighting (if pile driving was
occurring at time of sighting);
[cir] Estimated number of animals (min/max/best estimate);
[cir] Estimated number of animals by cohort (adults, juveniles,
neonates, group composition, sex class, etc.);
[cir] Animal's closest point of approach and estimated time spent
within the harassment zone; and
[cir] Description of any marine mammal behavioral observations
(e.g., observed behaviors such as feeding or traveling), including an
assessment of behavioral responses thought to have resulted from the
activity (e.g., no response or changes in behavioral state such as
ceasing feeding, changing direction, flushing, or breaching);
<bullet> Number of marine mammals detected within the harassment
zones and shutdown zones; by species; and
<bullet> Detailed information about any implementation of any
mitigation triggered (e.g., shutdowns and delays), a description of
specific actions that ensured, and resulting changes in behavior of the
animal(s), if any.
If no comments are received from NMFS within 30 days, the draft
reports will constitute the final reports. If comments are received, a
final report addressing NMFS comments must be submitted within 30 days
after receipt of comments.
Reporting Injured or Dead Marine Mammals
In the event that personnel involved in the construction activities
discover an injured or dead marine mammal, the USCG must immediately
cease the specified activities and report the incident to the Office of
Protected Resources (<a href="/cdn-cgi/l/email-protection#bcecee92f5e8ec92f1d3d2d5c8d3ced5d2dbeed9ccd3cec8cffcd2d3dddd92dbd3ca"><span class="__cf_email__" data-cfemail="0454562a4d50542a496b6a6d706b766d6a635661746b767077446a6b65652a636b72">[email&#160;protected]</span></a>), NMFS, and to
the Alaska Regional Stranding Coordinator as soon as feasible. If the
death or injury was clearly caused by the specified activity, the USCG
must immediately cease the specified activities until NMFS is able to
review the circumstances of the

[[Page 16681]]

incident and determine what, if any, additional measures are
appropriate to ensure compliance with the terms of the IHA. The USCG
must not resume their activities until notified by NMFS. The report
must include the following information:
<bullet> Time, date, and location (latitude/longitude) of the first
discovery (and updated location information if known and applicable);
<bullet> Species identification (if known) or description of the
animal(s) involved;
<bullet> Condition of the animal(s) (including carcass condition if
the animal is dead);
<bullet> Observed behaviors of the animal(s), if alive;
<bullet> If available, photographs or video footage of the
animal(s); and
<bullet> General circumstances under which the animal was
discovered.

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 discussion of our analysis applies to all
the species listed in table 8, given that the anticipated effects of
this activity on these different marine mammal stocks are expected to
be similar. There is little information about the nature or severity of
the impacts, or the size, status, or structure of any of these species
or stocks that would lead to a different analysis for this activity.
Pile driving and DTH activities associated with the specified
activities, as described previously, have the potential to disturb or
displace marine mammals. Specifically, the specified activities may
result in take in the form of Level A and/or Level B harassment from
underwater sounds generated from pile driving and DTH. Potential takes
could occur if individual marine mammals are present in the ensonified
areas above the thresholds for Level A harassment or Level B harassment
identified in table 6 when pile driving or DTH is occurring.
No serious injury or mortality would be expected, even in the
absence of required mitigation measures, given the nature of the
activities. For humpback, gray, minke, and killer whales (LF and HF
cetaceans), no Level A harassment is anticipated or proposed for
authorization due to the confined nature of the facility, ability to
position PSOs at stations from which they can observe the shutdown
zones, and the high visibility of these species. The potential for
harassment will be minimized through the construction method and the
implementation of the proposed mitigation measures (see Proposed
Mitigation section).
Take by Level A harassment is proposed for authorization for
Steller sea lion, harbor seal, harbor porpoise, and Dall's porpoise.
NMFS considers it unlikely that any individual would stay underwater
within the calculated Level A harassment isopleth for the entire
duration of a day of pile driving due to the general transient nature
of cetaceans in the habitat, and the ability of pinnipeds to haul out
on rocks and other structures. However, due to their relatively small
sizes and typically cryptic behaviors, it is possible individuals of
these species could enter the Level A harassment zone undetected and
remain within that zone for a duration long enough to incur AUD INJ.
Any take by Level A harassment is expected to arise from, at most, a
small degree of AUD INJ (i.e., minor degradation of hearing
capabilities within regions of hearing that align most completely with
the energy produced by impact pile driving such as the low-frequency
region below 2 kHz), not severe hearing impairment or impairment within
the ranges of greatest hearing sensitivity. Animals would need to be
exposed to higher levels and/or longer duration than are expected to
occur here in order to incur more than a small degree of AUD INJ.
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:
<bullet> No serious injury or mortality is anticipated or proposed
for authorization;
<bullet> Level A harassment would be very small amounts and of low
degree;
<bullet> Level B harassment would be primarily in the form of
behavioral disturbance, resulting in avoidance of the project area
around where piling is occurring, with some low-level TTS that may
limit the detection of acoustic cues for relatively brief amounts of
time in the relatively confined footprint of the activity;
<bullet> The ensonified area is very small relative to the overall
habitat ranges of all species and stocks, and would not adversely
affect ESA-designated critical habitat for any species or any areas of
known biological importance;
<bullet> The amount of take proposed for authorization accounts for
no more than, at most, 4 percent of any stock that may occur in the
project area;
<bullet> The lack of anticipated significant or long-term negative
effects to marine mammal habitat; and
<bullet> The implementation of mitigation measures to minimize the
number of marine mammals exposed to injurious levels of sound and
ensure take by Level A harassment is, at most, a small degree of AUD
INJ.
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 section 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

[[Page 16682]]

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 (see 86 FR 5322, January 19, 2021).
Additionally, other qualitative factors may be considered in the
analysis, such as the temporal or spatial scale of the activities.
The amount of take NMFS proposes to authorize is below one-third of
the estimated stock abundance of all species and stocks (take of
individuals is less than 4 percent of the abundance of all affected
stocks). This is likely a conservative estimate because it assumes all
takes are of different individual animals, which is likely not the
case. Some individuals may return multiple times in a day but PSOs
would count them as separate takes if they cannot be individually
identified.
There are no valid abundance estimates available for humpback
whales (Mexico-North Pacific stock), minke whales (Alaska stock),
Dall's porpoises (Alaska stock), and harbor porpoises (Yakutat/
Southeast Alaska Offshore Waters stock). The best available information
for each of these stocks is summarized below.
There is no recent stock abundance estimate for the Mexico-North
Pacific stock of humpback whale and the minimum population is
considered unknown (Young et al., 2024). There are two minimum
population estimates for this stock that are over 15 years old: 2,241
(Mart[iacute]nez-Aguilar, 2011) and 766 (Wade, 2021). Using either of
these estimates, the one take by Level B harassment proposed for
authorization represents small numbers of the stock. There is also no
current abundance estimate of the Alaska stock of minke whale, but over
2,000 individuals were documented in areas recently surveyed (Muto et
al., 2021). Therefore, the 31 takes by Level B harassment represents
small numbers of this stock, even if each take occurred to a new
individual.
The most recent stock abundance estimate of the Alaska stock of
Dall's porpoise was 83,400 animals and, although the estimate is more
than 8 years old, it is unlikely this stock has drastically declined
since that time. Therefore, the 46 takes proposed for authorization
represent small numbers of this stock.
A current stock-wide abundance estimate for the Yakutat/Southeast
Alaska Offshore Waters stock of harbor porpoises in offshore waters
(which includes Moorings Sitka) is not available (Young et al., 2023).
However, Muto et al. (2021) estimate the minimum stock size for the
areas surveyed is 1,057 individuals. Therefore, the 76 takes proposed
for authorization represent small numbers of this stock.
Based on the analysis contained herein of the proposed activity
(including the proposed mitigation and monitoring measures) and the
anticipated take of marine mammals, NMFS preliminarily finds that small
numbers of marine mammals would be taken relative to the population
size of the affected species or stocks.

Unmitigable Adverse Impact Analysis and Determination

In order to issue an IHA, NMFS must find that the specified
activity will not have an ``unmitigable adverse impact'' on the
subsistence uses of the affected marine mammal species or stocks by
Alaskan Natives. NMFS has defined ``unmitigable adverse impact'' in 50
CFR 216.103 as an impact resulting from the specified activity: (1)
that is likely to reduce the availability of the species to a level
insufficient for a harvest to meet subsistence needs by: (i) causing
the marine mammals to abandon or avoid hunting areas; (ii) directly
displacing subsistence users; or (iii) placing physical barriers
between the marine mammals and the subsistence hunters; and (2) that
cannot be sufficiently mitigated by other measures to increase the
availability of marine mammals to allow subsistence needs to be met.
A description of ``unmitigable adverse impact'' on the subsistence
uses of the affected marine mammal species or stocks by Alaskan Natives
was included in the notice of proposed IHA (89 FR 60359, July 25, 2024)
and the notice of the final IHA (89 FR 104090, December 20, 2024);
since that time, we are not aware of any changes in the subsistence use
of these species and stocks near Moorings Sitka. That information and
analysis is referenced in this proposed IHA modification and is not
repeated here; please refer to those notices.

Endangered Species Act

Section 7(a)(2) of the ESA of 1973 (16 U.S.C. 1531 et seq.)
requires that each Federal agency ensures 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 incidental take
authorizations, NMFS consults internally whenever we propose to
authorize take for ESA-listed species, in this case with the NMFS
Alaska Regional Office.
There are two marine mammal species (Western DPS Steller sea lion
and Mexico-North Pacific stock of humpback whale) with confirmed
occurrence in the project area that are listed under the ESA. The NMFS
Alaska Regional Office Protected Resources Division issued a Biological
Opinion on December 3, 2024, under section 7 of the ESA, on the
issuance of an IHA to the USCG under section 101(a)(5)(D) of the MMPA
by the NMFS Permits and Conservation Division. The Biological Opinion
concluded that the proposed action is not likely to jeopardize the
continued existence of Western DPS Steller sea lion or Mexico DPS of
humpback whale, and is not likely to destroy or adversely modify
critical habitat for Western DPS Steller sea lion or Mexico DPS of
humpback whale, as well as other ESA-listed species present at Moorings
Seward (Western North Pacific DPS of humpback whale and Northeast
Pacific stock of fin whale).
The Permits and Conservation Division has requested initiation of
section 7 consultation with the Alaska Regional Office for the issuance
of this modified IHA specific to the Sitka project area. NMFS will
conclude the ESA consultation prior to reaching a determination
regarding the proposed issuance of the authorization.

Proposed Authorization

As a result of these preliminary determinations, NMFS proposes to
issue an IHA to the USCG for construction of a FRC homeporting dock in
Sitka for a period of 1 year, provided the previously mentioned
mitigation, monitoring, and reporting requirements are incorporated. A
draft of the proposed IHA modification can be found at: <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities">https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities</a>.

Request for Public Comments

We request comment on our analyses, the proposed authorization
modification, and any other aspect of this notice of proposed IHA
modification for the proposed construction project. Please include with
your comments any supporting data or literature citations to help
inform decisions on the request for this IHA modification.

[[Page 16683]]

Dated: March 30, 2026.
Kimberly Damon-Randall,
Director, Office of Protected Resources, National Marine Fisheries
Service.
[FR Doc. 2026-06394 Filed 4-1-26; 8:45 am]
BILLING CODE 3510-22-P

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