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Proposed Rule2025-11499

Marine Mammals; Incidental Take of Northern Sea Otters During Specified Activities; Seward, Sitka, and Kodiak, Alaska

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Published

June 23, 2025

Issuing agencies

Interior DepartmentFish and Wildlife Service

Abstract

We, the U.S. Fish and Wildlife Service, in response to a request under the Marine Mammal Protection Act of 1972, as amended, from the U.S. Coast Guard, propose to issue regulations for the nonlethal, incidental, unintentional take by harassment of small numbers of Southcentral Alaska, Southeast Alaska, and Southwest Alaska stocks of northern sea otters (Enhydra lutris kenyoni) during pile driving and marine construction activities in Seward, Sitka, and Kodiak, Alaska. Incidental take of northern sea otters may result from in-water noise generated during pile driving and marine construction activities occurring for a period up to 5 years. This proposed rule would authorize take by harassment only, and no lethal take would be authorized. If this rule is finalized, we will issue letters of authorization for the incidental take of northern sea otters, upon request, for specific activities in accordance with the final rule for a period up to 5 years. We request comments on these proposed regulations.

Full Text

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<title>Federal Register, Volume 90 Issue 118 (Monday, June 23, 2025)</title>
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[Federal Register Volume 90, Number 118 (Monday, June 23, 2025)]
[Proposed Rules]
[Pages 26486-26520]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2025-11499]

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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 18

[Docket No. FWS-R7-ES-2024-0195; FXES111607MRG01-245-FF07CAMM00]
RIN 1018-BI08

Marine Mammals; Incidental Take of Northern Sea Otters During
Specified Activities; Seward, Sitka, and Kodiak, Alaska

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Notification of receipt of application; proposed rule;
availability of draft environmental assessment; request for comments.

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SUMMARY: We, the U.S. Fish and Wildlife Service, in response to a
request under the Marine Mammal Protection Act of 1972, as amended,
from the U.S. Coast Guard, propose to issue regulations for the
nonlethal, incidental, unintentional take by harassment of small
numbers of Southcentral Alaska, Southeast Alaska, and Southwest Alaska
stocks of northern sea otters (Enhydra lutris kenyoni) during pile
driving and marine construction activities in Seward, Sitka, and
Kodiak, Alaska. Incidental take of northern sea otters may result from
in-water noise generated during pile driving and marine construction
activities occurring for a period up to 5 years. This proposed rule
would authorize take by harassment only, and no lethal take would be
authorized. If this rule is finalized, we will issue letters of
authorization for the incidental take of northern sea otters, upon
request, for specific activities in accordance with the final rule for
a period up to 5 years. We request comments on these proposed
regulations.

DATES: Comments on these proposed incidental take regulations and the
accompanying draft environmental assessment will be accepted on or
before July 23, 2025. Comments submitted electronically using the
Federal eRulemaking Portal (see ADDRESSES, below) must be received by
11:59 p.m. eastern time on the closing date.
Information collection requirements: If you wish to comment on the
information collection requirements in this proposed rule, please note
that the Office of Management and Budget (OMB) is required to make a
decision concerning the collection of information contained in this
proposed rule between 30 and 60 days after publication of this

[[Page 26487]]

proposed rule in the Federal Register. Therefore, comments should be
submitted to OMB, with a copy to the FWS Information Collection
Clearance Officer, U.S. Fish and Wildlife Service, (see ``Information
Collection'' section below under ADDRESSES) by August 22, 2025.

ADDRESSES: Document availability: You may view the application package,
the associated draft environmental assessment, comments received, and
other supporting material at <a href="https://www.regulations.gov">https://www.regulations.gov</a> under Docket
No. FWS-R7-ES-2024-0195, or these documents may be requested as
described under FOR FURTHER INFORMATION CONTACT.
Comment submission: You may submit comments on the proposed rule
and draft environmental assessment by one of the following methods:
<bullet> Electronic submission: Federal eRulemaking Portal at:
<a href="https://www.regulations.gov">https://www.regulations.gov</a>. Follow the instructions for submitting
comments to Docket No. FWS-R7-ES-2024-0195.
<bullet> U.S. mail: Public Comments Processing, Attn: Docket No.
FWS-R7-ES-2024-0195, Policy and Regulations Branch, U.S. Fish and
Wildlife Service, MS: PRB (JAO/3W), 5275 Leesburg Pike, Falls Church,
VA 22041-3803.
We will post all comments at <a href="https://www.regulations.gov">https://www.regulations.gov</a>. You may
request that we withhold personal identifying information from public
review; however, we cannot guarantee that we will be able to do so. See
Request for Public Comments for more information.
Information collection requirements: Written comments and
suggestions on the information collection requirements should be
submitted within 60 days of publication of this notice to <a href="https://www.reginfo.gov/public/do/PRAMain">https://www.reginfo.gov/public/do/PRAMain</a>. Find this particular information
collection by selecting ``Currently under Review--Open for Public
Comments'' or by using the search function. Please provide a copy of
your comments to the FWS Information Collection Clearance Officer, U.S.
Fish and Wildlife Service, 5275 Leesburg Pike, MS: PRB (JAO/3W), Falls
Church, VA 22041-3803 (mail); or <a href="/cdn-cgi/l/email-protection#4f06212920100c2023230f29383c61282039">[email&#160;protected]</a> (email). Please
reference ``RIN 1018-BI08'' in the subject line of your comments.

FOR FURTHER INFORMATION CONTACT: Stephanie Burgess, by email at
<a href="/cdn-cgi/l/email-protection#e5b7d2888888978082908984918a979ca5839296cb828a93">[email&#160;protected]</a> or by telephone 907-786-3800. Individuals in
the United States who are deaf, deafblind, hard of hearing, or have a
speech disability may dial 711 (TTY, TDD, or TeleBraille) to access
telecommunications relay services. Individuals outside the United
States should use the relay services offered within their country to
make international calls to the point-of-contact in the United States.
Please see Docket No. FWS-R7-ES-2024-0195 on <a href="https://www.regulations.gov">https://www.regulations.gov</a> for a document that summarizes this proposed rule.

SUPPLEMENTARY INFORMATION:

Executive Summary

In accordance with the Marine Mammal Protection Act of 1972 (16
U.S.C. 1371(a)(5)(A)) and its implementing regulations, we, the U.S.
Fish and Wildlife Service (hereafter FWS or we), propose incidental
take regulations that, if finalized, would allow through Letters of
Authorization (LOAs) the nonlethal, incidental, unintentional take of
small numbers of northern sea otters (Enhydra lutris kenyoni) during
pile driving and marine construction in Seward, Sitka, and Kodiak,
Alaska. If finalized, the rule would be effective for 5 years from the
date of issuance.
This proposed rule is based on our preliminary findings that the
total takings of sea otters during specified activities will impact
small numbers of animals, will have a negligible impact on this species
or stocks, and will not have an unmitigable adverse impact on the
availability of northern sea otters for subsistence use by Alaska
Natives. We base our preliminary findings on the best available
scientific evidence, including but not limited to, data from monitoring
the encounters and interactions between sea otters and pile driving and
marine construction activities; research on northern sea otters;
potential and documented effects on this species from similar
activities; information regarding the natural history and conservation
status of sea otters; and data reported from Alaska Native subsistence
hunters. In conjunction with this proposed rulemaking, we have prepared
a draft environmental assessment, which is also available for public
review and comment.
The proposed regulations include permissible methods of nonlethal
taking; mitigation measures to ensure that the activities of the U.S.
Coast Guard (USCG) will have the least practicable adverse impact on
the northern sea otters, their habitat, and the availability of this
species for subsistence uses; and requirements for monitoring and
reporting. Compliance with this rule, if finalized, is not expected to
result in significant additional costs to the applicant, and any costs
are minimal in comparison to those related to actual pile driving and
marine construction activities.

Background

Section 101(a)(5)(A) of the Marine Mammal Protection Act (MMPA) (16
U.S.C. 1371(a)(5)(A)) gives the Secretary of the Interior (Secretary)
the authority to allow the incidental, but not intentional, taking of
small numbers of certain marine mammals, in response to requests by
U.S. citizens (as defined in title 50 of the Code of Federal
Regulations (CFR) in part 18 (at 50 CFR 18.27(c)) engaged in a
specified activity (other than commercial fishing) within a specified
geographic region. The Secretary has delegated authority for
implementation of the MMPA to the FWS. According to the MMPA, the FWS
shall allow this incidental taking for a period of up to 5 consecutive
years if we find that the total of such taking:
(1) will affect only small numbers of individuals of the species or
stock;
(2) will have no more than a negligible impact on the species or
stock; and
(3) will not have an unmitigable adverse impact on the availability
of the species or stock for taking for subsistence use by Alaska
Natives.
If the requisite findings are made, we issue regulations that set
forth the following, where applicable:
(a) permissible methods of taking;
(b) means of effecting the least practicable adverse impact on the
species or stock and its habitat and the availability of the species or
stock for subsistence uses; and
(c) requirements for monitoring and reporting of such taking.
If final regulations allowing such incidental take are issued, we
may then subsequently issue letters of authorization (LOA), upon
request, to authorize incidental take during the specified activities.
The term ``take'' means to ``harass, hunt, capture, or kill, or
attempt to harass, hunt, capture, or kill any marine mammal'' (16
U.S.C. 1362(13)). Harassment for activities other than military
readiness activities or scientific research conducted by or on behalf
of the Federal Government means any act of pursuit, torment, or
annoyance that has the potential to injure a marine mammal or marine
mammal stock in the wild (the MMPA defines this as Level A harassment),
or 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 (the MMPA defines this as

[[Page 26488]]

Level B harassment) (16 U.S.C. 1362(18)).
The terms ``negligible impact'' and ``unmitigable adverse impact''
are defined in 50 CFR 18.27(c) (i.e., regulations governing small takes
of marine mammals incidental to specified activities) as follows:
``Negligible impact'' is 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. ``Unmitigable adverse impact''
means an impact resulting from the specified activity: (1) that is
likely to reduce the availability of the species to a level
insufficient for a harvest to meet subsistence needs by (i) causing the
marine mammals to abandon or avoid hunting areas, (ii) directly
displacing subsistence users, or (iii) placing physical barriers
between the marine mammals and the subsistence hunters; and (2) that
cannot be sufficiently mitigated by other measures to increase the
availability of marine mammals to allow subsistence needs to be met.
The term ``small numbers'' is also defined in 50 CFR 18.27(c).
However, we do not rely on that definition here as it conflates ``small
numbers'' with ``negligible impact.'' We recognize ``small numbers''
and ``negligible impacts as two separate and distinct requirements for
promulgating incidental take regulations (ITR) under the MMPA (see
Natural Res. Def. Council, Inc. v. Evans, 232 F. Supp. 2d 1003, 1025
(N.D. Cal. 2003)). Instead, for our small numbers determination, we
estimate the likely number of marine mammals to be taken and evaluate
if that take is small relative to the size of the species or stock.
The term ``least practicable adverse impact'' is not defined in the
MMPA or its enacting regulations. In promulgating ITRs, we ensure the
least practicable adverse impact by requiring mitigation measures that
are effective in reducing the impact of specified activities, but they
are not so restrictive as to make specified activities unduly
burdensome or impossible to undertake and complete.
The USCG's activities may result in the incidental taking of sea
otters. The MMPA does not require that the USCG must obtain incidental
take authorization prior to conducting these activities; however, any
incidental taking that occurs without authorization is a violation of
the MMPA. An ITR was issued to the USCG for pile driving and marine
construction activities at multiple locations in Alaska including
Seward, Sitka, and Kodiak from May 19, 2023, through May 19, 2028 (88
FR 24115, April 19, 2023). The specified activities described in this
proposed ITR are outside the scope of the 2023-2028 USCG ITR, and,
therefore, the USCG submitted requests for the incidental take of sea
otters during their planned activities.

Summary of Request

On March 5, 2024, the FWS received a request prepared by Weston
Solutions on behalf of the U.S. Coast Guard (hereafter, USCG or the
applicant) for the nonlethal, incidental harassment of small numbers of
northern sea otters (Enhydra lutris kenyoni) (hereafter, sea otters
unless another sea otter subspecies is specified) from the Southwest
Alaska stock that may occur during pile driving and marine construction
activities in Womens Bay, Kodiak, Alaska. During discussion with the
applicant, a request prepared by WSP Environment and Infrastructure on
behalf of the USCG (received January 19, 2024) for the nonlethal,
incidental harassment of small numbers of sea otters from the
Southcentral Alaska stock that may occur during pile driving and marine
construction activities in Seward was combined with the USCG's request
prepared by Weston Solutions. Additionally, a request prepared by WSP
Environment and Infrastructure on behalf of the USCG (received January
19, 2024) for the nonlethal, incidental harassment of small numbers of
sea otters from the Southeast Alaska stock that may occur during pile
driving and marine construction activities in Sitka was then merged
with the USCG's combined request. The USCG provided additional
information regarding project activities, timelines, and mitigation
measures for their planned activities in Kodiak, Seward, and Sitka
requested by the FWS during correspondence. On October 2, 2024, the FWS
received a revised application for activities in Kodiak (hereafter
referred to as ``Weston Solutions 2024 Request''). On October 3, 2024,
the FWS received a revised application for activities in Seward and
Sitka (hereafter referred to as ``WSP Environment and Infrastructure
2024 Request''). The FWS determined USCG's combined request for
activities in Kodiak, Seward, and Sitka to be adequate and complete on
October 3, 2024.
The applicant expects take by harassment may occur during pile
driving and marine construction activities at three facilities in
Alaska: the USCG Moorings Seward in Seward; the USCG Moorings Sitka in
Sitka; and the USCG Base Kodiak near Kodiak. These improvements are
needed to support the commission, temporary and permanent homeporting,
and berthing of Fast Response Cutters (FRCs) at all three facilities
and Offshore Patrol Cutters (OPC) at Kodiak. Hereafter (unless
otherwise specified), the terms ``pile driving'' and ``pile-driving
activities'' are used to refer to both pile installation and pile
removal.

Description of the Proposed Regulations

The proposed regulations, if finalized, would allow through LOAs
the authorization of nonlethal, incidental, unintentional take of small
numbers of sea otters that may result from the specified activities
based on standards set forth in the MMPA. They would not authorize or
``permit'' the activities being conducted by the USCG, only the
incidental take of sea otters that may result from those activities.
The proposed regulations include:
(1) Permissible methods of nonlethal taking;
(2) Measures designed to ensure the least practicable adverse
impact on sea otters and their habitat, and on the availability of this
species or stock for subsistence uses; and
(3) Requirements for monitoring and reporting.

Description of Letters of Authorization (LOAs)

An LOA is required to conduct activities pursuant to an ITR. Under
this proposed ITR, if finalized, the applicant may request an LOA for
the authorized nonlethal, incidental Level B and Level A harassment of
sea otters incidental to the specific activities described in these
proposed regulations. Per the applicant's request, such entities would
be limited to the USCG and their subcontractors. Requests for LOAs must
be consistent with the activity descriptions and mitigation and
monitoring requirements of the ITR and be received in writing at least
30 days before the activity is to begin. Requests must include (1) an
operational plan for the activity, including the number of days of work
and the nature of work to be conducted; (2) a digital geospatial file
of the project footprint; (3) a site-specific marine mammal monitoring
and mitigation plan that specifies the procedures to monitor and
mitigate the effects of the activities on sea otters; and (4) Plans of
Cooperation (if required as described below). Once this information has
been received, we will evaluate each request and issue the LOA for up
to a 1-year period if we find that the level of taking will be
consistent with the findings made for the total taking allowable under
the ITR. Requests for LOAs may be submitted on an annual

[[Page 26489]]

basis for additional years of activities within the ITR period. We must
receive an after-action report on the monitoring and mitigation
activities within 90 days after the LOA expires. For more information
on requesting and receiving an LOA, refer to 50 CFR 18.27(f).

Description of Plans of Cooperation (POCs)

A POC is a documented plan describing measures to mitigate
potential conflicts between specified activities and Alaska Native
subsistence hunting. The circumstances under which a POC must be
developed and submitted with a request for an LOA are described below.
To help ensure that specified activities do not have an unmitigable
adverse impact on the availability of the species for Alaska Native
subsistence hunting opportunities, all applicants requesting an LOA
under this ITR must provide the FWS documentation of communication and
coordination with Alaska Native communities potentially affected by the
specified activity and, as appropriate, with representative subsistence
hunting and co-management organizations. If Alaska Native communities
or representative subsistence hunting organizations express concerns
about the potential impacts of specified activities on subsistence
activities, and such concerns are not resolved during this initial
communication and coordination process, then a POC must be developed
and submitted with the applicant's request for an LOA. In developing
the POC, the USCG will further engage with Alaska Native communities
and/or representative subsistence hunting organizations to provide
information and respond to questions and concerns. The POC must provide
adequate measures to ensure that specified activities will not have an
unmitigable adverse impact on the availability of sea otters for Alaska
Native subsistence uses.

Description of Specified Geographic Region and Specified Activities

The specified geographic region includes Gulf of Alaska coastal
waters of three USCG facilities. The specified activities would occur
in the waters and intertidal areas of the eastern shore of Resurrection
Bay, Alaska, surrounding the USCG Moorings Seward, the waters and
intertidal areas of Sitka Channel, Alaska, surrounding the USCG
Moorings Sitka, and the waters and intertidal areas of Womens Bay,
Kodiak, Alaska, which surround the USCG Base Kodiak located on the
Nyman Peninsula (figure 1).
[GRAPHIC] [TIFF OMITTED] TP23JN25.012

Figure 1--Specific Geographic Region

Three pile driving and marine construction projects would occur
within the specified geographic region: Moorings Seward, Moorings
Sitka, and Base Kodiak. Brief summaries of each project are provided
below, and additional project details for each project may be reviewed
in the application materials available as described under ADDRESSES or
may also be requested as described under FOR FURTHER INFORMATION
CONTACT.

[[Page 26490]]

Moorings Seward Activities

The specified activity (hereafter project) in Seward will include
installation and removal of piles for the construction of shoreside
facilities and associated infrastructure at the USCG Moorings Seward in
the Seward Marine Industrial Center (SMIC) to homeport 1 FRC. The
project entails construction of a new floating dock parallel to the
existing SMIC dock and reconfiguration of the SMIC floating dock to
allow for construction of the FRC moorings. For the reconfiguration of
the SMIC floating dock, project activities include the removal of up to
10 existing steel guide piles that are no greater than 40.6 centimeters
(cm; 16 inches (in)) in diameter and the installation of up to 10 new
concrete or steel pipe guide piles that are 76.2 cm (30 in) in
diameter. Construction of the new dock includes installation of up to
20 concrete or steel pipe guide piles that are no greater than 76.2 cm
(30 in) in diameter. In-water project activities are summarized in
table 1. After the dock is installed, ancillary infrastructure (i.e.,
electricity, water, sewage) to service the docked FRC will be
installed. Pile-driving activities will occur over 22 non-consecutive
days for approximately 105 hours. Pile removal will be done with
vibratory extraction or cutting at the mud line with a pile clipper or
diamond saw. Pile installation will be done with a combination of rock
socket down-the-hole (DTH) drilling, impact proofing, and vibratory
settling.

Table 1--USCG Moorings Seward: Project Activities, Piles Installed or Removed, and Days of Activity
----------------------------------------------------------------------------------------------------------------
Total Maximum number Maximum number
Project component Pile size and Activity number of of piles per of days of
material piles day activity
----------------------------------------------------------------------------------------------------------------
FRC moorings............ <40.6-cm (<16-in) Removal--vibratory. 10 5 2
steel.
Removal--pile 5
clipper.
Removal--diamond 5
wire saw.
76.2-cm (30-in) Installation--rock 10 2 20
concrete or steel. socket DTH.
Installation--vibra 2
tory settling.
Installation--impac 2
t proofing.
New dock................ 76.2-cm (30-in) Installation--rock 20 2
concrete or steel. socket DTH.
Installation--vibra 2
tory settling.
Installation--impac 2
t proofing.
----------------------------------------------------------------------------------------------------------------

Moorings Sitka Activities

The USCG plans to remove a mooring dolphin supported by four
concrete piles, each of which is 61.0 cm (24 in) in diameter, and a
float supported by six timber piles, each of which is 35.6 cm (14 in)
in diameter. To support the pier, floating dock, and mooring dolphins,
the USCG plans to install 118 concrete piles, each of which will be
76.2 cm (30 in) in diameter; 54 plastic piles, each of which will be
33.0 cm (13 in) in diameter; and 6 timber piles, each of which will be
35.6 cm (14 in) in diameter. Pile-driving activities will occur over
117 non-consecutive days. Pile installation will be done with a
combination of impact pile driving, vibratory pile driving, and DTH
drilling. Temporary and existing piles will be removed by the dead-pull
method (a direct lift of the pile using a crane with no vibration), a
pile clipper, a diamond saw, or a vibratory hammer. In-water activities
are summarized in table 2.

Table 2--USCG Moorings Sitka: Project Activities, Piles Installed or Removed, and Days of Activity
----------------------------------------------------------------------------------------------------------------
Total Maximum number Maximum number
Project component Pile size and Activity number of of piles per of days of
material piles day activity
----------------------------------------------------------------------------------------------------------------
Demolition.............. 61.0-cm (24-in) Removal--vibratory. 4 5 1
concrete.
Removal--pile 5
clipper.
Removal--diamond 5
wire saw.
35.6-cm (14-in) Removal--vibratory. 6 5 2
timber.
Construction............ 76.2-cm (30-in) Installation--rock 118 2 84
concrete or steel. socket DTH.
Installation--vibra 2
tory settling.
Installation--impac 2
t proofing.
35.6-cm (14-in) Installation--impac 6 2 3
timber. t driving.
33.0-cm (13-in) Installation--impac 54 2 27
composite. t driving.
----------------------------------------------------------------------------------------------------------------

Base Kodiak Activities

The USCG will implement in-water and waterfront improvements at the
USCG Base Kodiak to support the commission, temporary and permanent
homeporting, and berthing of FRCs and OPCs. In-water improvements will
consist of replacing and extending existing wharfs, installing floating
docks and camel logs, installing a solid-fill approach bulkhead, and
refurbishing small craft floats. In-water activities will include
impact pile driving of steel piles and concrete fender piles, vibratory
installation and extraction of timber piles, steel piles, steel/
concrete piles, concrete piles, and vibroflot columns, and DTH drilling
of steel piles. These activities are anticipated to occur over 339 non-
consecutive days from 2 to 5 years. A total of 501 piles of various
sizes and types will be removed throughout the project. A total of 918
piles of various sizes and types will be installed throughout the
project. In-water activities are summarized in table 3.

[[Page 26491]]

Table 3--USCG Base Kodiak: Project Activities, Piles Installed or Removed, and Days of Activity
----------------------------------------------------------------------------------------------------------------
Total Maximum number
Project Pile size and number of Maximum number of days of
Project component year material Activity piles per of piles per activity per
year day year
----------------------------------------------------------------------------------------------------------------
Demolition........... 1 35.6-cm (14-in) Removal-vibrato 158 20 10
timber. ry.
61.0-cm (24-in) 24 20 2
timber.
30.5-cm (12-in) 147 20 9
steel.
35.6-cm (14-in) 30 20 2
steel.
Construction......... 61.0-cm (24-in) Installation--v 22 6 5
steel. ibratory.
Installation--i 22 6 5
mpact.
Installation--D 11 2 7
TH.
76.2-cm (30-in) Installation--v 488 10 59
vibroflot ibratory.
columns.
91.4-cm (36-in) Temporary 94 6 19
steel. installation--
vibratory.
Temporary 94 6 19
removal--vibra
tory.
106.7-cm (42-in) Installation--v 160 6 32
steel. ibratory.
Installation--i 160 6 32
mpact.
61.0-cm (24-in) Removal--vibrat 4 20 1
steel/concrete. ory.
61.0-cm (24-in) Installation--v 35 6 7
precast ibratory.
concrete
reaction.
61.0-cm (24-in) Installation--i 35 6 7
precast mpact.
concrete fender.
63.5-106.7-cm Installation--D 80 2 48
(25-42-in) TH.
steel.
2 61.0-cm (24-in) Installation--v 20 6 4
steel. ibratory.
Installation--i 20 6 4
mpact.
Installation--D 10 2 6
TH.
76.2-cm (30-in) Installation--v 23 6 5
steel. ibratory.
Installation--i 23 6 5
mpact.
91.4-cm (36-in) Permanent 8 4 3
steel. installation--
vibratory.
Permanent 8 4 3
installation--
impact.
Temporary 44 6 9
installation--
vibratory.
Temporary 44 6 9
removal--vibra
tory.
106.7-cm (42-in) Installation--v 24 6 5
steel. ibratory.
Installation--i 24 6 5
mpact.
63.5-106.7-cm Installation--D 28 2 17
(25-42-in) TH.
steel.
----------------------------------------------------------------------------------------------------------------

Description of Marine Mammals in the Specified Geographic Region

Sea Otter Biology

There are three sea otter stocks in Alaska: the Southeast Alaska
stock, the Southcentral Alaska stock, and the Southwest Alaska stock.
All three Alaskan sea otter stocks are present in the project area. Sea
otters at the USCG Moorings Seward belong to the Southcentral Alaska
stock. Sea otters at Moorings Sitka belong to the Southeast Alaska
stock. Sea otters at the USCG Base Kodiak belong to the Southwest
Alaska stock. Detailed information about the biology of these stocks
can be found in the most recent stock assessment reports (88 FR 53510,
August 8, 2023), which can be found at <a href="https://fws.gov/project/marine-mammal-stock-assessment-reports">https://fws.gov/project/marine-mammal-stock-assessment-reports</a>. Additionally, the Southwest Alaska
stock of sea otters is listed as threatened under the Endangered
Species Act (ESA; 16 U.S.C. 1531 et seq.) at 50 CFR 17.11(h) (70 FR
46366; August 9, 2005). Further information on the Southwest Alaska
stock is available in the FWS's species status assessment available at:
<a href="https://ecos.fws.gov/ecp/species/2884">https://ecos.fws.gov/ecp/species/2884</a>.
Northern sea otters occur in nearshore coastal waters from Alaska's
Aleutian Islands to Washington (88 FR 53510, August 8, 2023). Sea
otters may be distributed anywhere within the specified geographic
region other than upland areas; however, they generally occur in
shallow water near the shoreline. They are most commonly observed
within the 40-meter (m) (131-foot [ft]) depth contour (88 FR 53510,
August 8, 2023), although they can be found in areas with deeper water.
Ocean depth is generally correlated with distance to shore, and sea
otters typically remain within 1 to 2 kilometers (km) (0.6 to 1.2 miles
[mi]) of shore (Riedman and Estes 1990). They tend to be found closer
to shore during storms but move farther out during good weather and
calm seas (Lensink 1962; Kenyon 1969).
Sea otters are nonmigratory and generally do not disperse over long
distances (Garshelis and Garshelis 1984), usually remaining within a
few kilometers of their established feeding grounds (Kenyon 1981;
Barocas and Ben-David 2021). Breeding males may stay for all or part of
the year in a breeding territory ranging from 4 to 11 square kilometers
(km\2\) (1.5 to 4.2 square miles [mi\2\]) (Garshelis and Garshelis
1984; Riedman and Estes 1990; 88 FR 53510, August 8, 2023), while adult
females maintain home ranges of approximately 1 to 16 km (0.6 to 10
mi), which may include one or more male breeding territories (Kenyon
1969; Garshelis and Garshelis 1984; Riedman and Estes 1990). Juveniles
disperse greater distances after weaning (Garshelis and Garshelis 1984;
Garshelis et al. 1984; Monnett and Rotterman 1988; Riedman and Estes
1990). Although sea otters generally remain local to an area, they are
capable of long-distance travel. Sea otters in Alaska have shown daily
movement distances greater than 3 km (1.9 mi) at speeds up to 5.5 km
per hour (3.4 mi per hour) (Garshelis and Garshelis 1984).

Southcentral Alaska Sea Otter Stock

The Southcentral Alaska sea otter stock occurs in the center of the
sea otter range in Alaska and extends from Cape Yakataga in the east to
Cook Inlet in the west, including Prince William Sound (PWS), the
eastern Kenai Peninsula coast, and Kachemak Bay (88 FR 53510, August 8,
2023). Between 2014 and 2019, aerial surveys were conducted in three
regions of the Southcentral Alaska sea otter stock: (1) Eastern Cook
Inlet, (2) Outer Kenai Peninsula, and (3) PWS by aerial transects flown
at 91 m (~299 ft) of altitude. The combined estimates of the 3 regions
resulted in approximately 21,617 sea otters (with a 95 percent
confidence interval of 17,324 to 25,910 sea otters) and an average
density of 1.96 sea otters/km\2\ for the Southcentral Alaska stock
(Esslinger et al. 2021; 88 FR 53510, August 8, 2023). The trend for the
Southcentral Alaska sea otter stock has either increased or remained
stable across surveyed areas since the FWS's previous stock assessment
report

[[Page 26492]]

in 2014 (88 FR 53510, August 8, 2023). The maximum rate of
productivity, which is the maximum net annual increment in population
numbers, for the Southcentral stock is estimated at 29 percent
(Eisaguirre et al. 2021; 88 FR 53510, August 8, 2023). The Southcentral
Alaska sea otter stock is classified as non-strategic under the MMPA
(88 FR 53510, August 8, 2023).

Southeast Alaska Sea Otter Stock

The Southeast Alaska sea otter stock boundaries include Dixon
Entrance Strait at the U.S.-Canada border to the south and Cape
Yakataga to the north (88 FR 53510, August 8, 2023). However, the
largest abundances of sea otters in Southeast Alaska are found in the
northern part of this range and expanding south to east (Tinker et al.
2019). Sea otters from this stock prefer shallow waters (<40 m in
depth), areas close to shore, areas with bathymetric variation (i.e.,
steep slopes), and areas with straight shorelines (Eisaguirre et al.
2021).
The most recent abundance survey of the Southeast Alaska sea otter
stock was conducted in 2022. The stock is estimated at 22,359 sea
otters (with a 95 percent Bayesian credible interval of 19,595 to
25,290 sea otters) based on recent photo-based survey data, historic
aerial survey data, and an applied ecological diffusion model to
calculate stock-wide abundance (Eisaguirre et al. 2021, 2023; Schuette
et al. 2023; 88 FR 53510, August 8, 2023). The trend for the Southeast
Alaska sea otter stock has increased steadily over time (Schuette et
al. 2023; 88 FR 53510, August 8, 2023). The maximum productivity rate
is estimated at 29 percent (Eisaguirre et al. 2021; 88 FR 53510, August
8, 2023). This stock is classified as non-strategic under the MMPA (88
FR 53510, August 8, 2023). Abundance values within the Moorings Sitka
project area ranged from 0.065 to 0.65 sea otters/km\2\.

Southwest Alaska Sea Otter Stock

The Southwest Alaska sea otter stock occurs from western Cook Inlet
to Attu Island in the Aleutian chain (88 FR 53510, August 8, 2023).
Between 2014 and 2021, surveys to estimate sea otter population size
were conducted in the following locations: Aleutian Islands, Bristol
Bay, South Alaska Peninsula, Kodiak Archipelago, Katmai National Park,
western Cook Inlet, and Kamishak Bay (USFWS 2020; 88 FR 53510, August
8, 2023). The combined population estimates from these surveys resulted
in a total estimate of 51,935 sea otters for the Southwest Alaska sea
otter stock (a global coefficient of variation is unavailable for the
Southwest Alaska stock due to the different survey methods and
analytical approaches used for population assessments in each of the
five management units). The overall trend for the Southwest Alaska sea
otter stock is generally stable to increasing (88 FR 53510, August 8,
2023). The maximum rate of productivity is estimated at 29 percent
(Eisaguirre et al. 2021; 88 FR 53510, August 8, 2023).
The Southwest Alaska sea otter stock was listed as threatened under
the ESA in 2005 as a distinct population segment (DPS) due to sea otter
population declines throughout the stock's range (70 FR 46366, August
9, 2005). A rule for this stock under section 4(d) of the ESA was
promulgated in 2006 (71 FR 46864, August 15, 2006), and critical
habitat was designated for the stock in 2009 (74 FR 51988, October 8,
2009). Sea otter critical habitat consists of areas within the 20-m
(66-ft) depth contour, areas within the 100-m (328-ft) nearshore
waters, and areas where the 20-m (66-ft) depth contour and 100-m (328-
ft) nearshore waters overlap (74 FR 51988, October 8, 2009). The
specified activities that would occur at Kodiak overlap with 1.61 km\2\
(0.62 mi\2\) of critical habitat for the Southwest Alaska sea otter
stock. Sea otters' preference for shallow water may be related to
diving depth limits and avoidance of large predators, such as killer
whales (Orcinus orca) (Wilson et al. 2021; Monson 2021; Tinker et al.
2023), which have purportedly contributed to recent declines in the
Southwest Alaska sea otter stock (78 FR 54905, September 6, 2013;
Tinker et al. 2021). Sea otters' frequent use of shallow waters to
avoid predation has allowed sea otter populations in the Southwest
Alaska stock to persist, but this preference for shallow waters
restricts habitat use and reduces population connectivity, which can
impact population recovery (Tinker et al. 2023).
Under the ESA, the Southwest Alaska sea otter stock is divided into
five management units (MU): Western Aleutians; Eastern Aleutians; South
Alaska Peninsula; Bristol Bay; and Kodiak, Kamishak, and Alaska
Peninsula (88 FR 53510, August 8, 2023). The specified geographic
region occurs within the range of the Kodiak, Kamishak, and Alaska
Peninsula MU.
The range of the Kodiak, Kamishak, and Alaska Peninsula MU extends
from Chignik Bay to Western Cook Inlet on the southern side of the
Alaska Peninsula, and it also encompasses Kodiak Island (USFWS 2020).
The specified geographic region is within the range of the sea otter
population at Kodiak Archipelago. The most recent aerial surveys to
estimate sea otter population size in the Kodiak Archipelago were
conducted in 2014. The overall sea otter density estimate within this
area was 1.56 sea otters/km\2\ (Cobb 2018; USFWS 2020). The population
trend for sea otters in the Kodiak Archipelago appears to be increasing
between the 2004 and 2014 surveys after exhibiting a decline between
the 1994 and 2001 surveys (88 FR 53510, August 8, 2023). Sea otters
were not uniformly distributed throughout the Kodiak Archipelago. Sea
otter density was estimated to be 2.54 sea otters/km\2\ in high sea
otter density area, which is the area between shore and 400 m (1,312
ft) seaward, or the 40-m (131-ft) depth contour, whichever was greater.
Sea otter density was estimated to be 0.30 sea otters/km\2\ in low sea
otter density area, which is the area between the high sea otter
density area boundary and 2 km (1.2 mi) offshore, or the 100-m (328-ft)
depth contour, whichever was greater (Cobb 2018). Sea otter density was
highest in the straits between Kodiak, Raspberry, and Shuyak Islands.
Few sea otters were observed on the eastern side of Kodiak Island (Cobb
2018).

Climate Change

The effects of climate change in the northern latitudes include
increases in water and air temperatures, reductions in seasonal sea
ice, increases in acidity of seawater, increases in coastal erosion,
and changes in timing and intensity of storm events (Intergovernmental
Panel on Climate Change 2014). Increasing ocean temperatures and
changes in sea ice could allow species to expand or change their
traditional ranges, allowing species that were previously
geographically isolated from one another to share the same area. This
interaction between species could introduce novel pathogens into
populations. For example, phocine distemper virus was introduced to
marine mammals in the Pacific Ocean, likely by seals traveling from the
Atlantic Ocean (Goldstein et al. 2009). The loss of sea ice may
facilitate additional introductions of novel pathogens to marine
mammals in the Arctic and Pacific Oceans. Sea otters are susceptible to
mortality from infections by a number of viruses, bacteria, and
parasites (Burek-Huntington et al. 2021; Barratclough et al. 2023). For
example, Strep syndrome has been recorded as one of the leading causes
of death in northern sea otters in Alaska, especially in subadults who
have not yet reproduced (Burek-Huntington et al. 2021; Barratclough et
al. 2023). It is unknown what the long-term impacts of diseases are for
sea otter populations

[[Page 26493]]

and how climate change may affect disease rates in sea otter
populations.
Climate change may also indirectly affect sea otters by altering
the abundance, distribution, composition, and the quality of benthic
invertebrates (Wassmann et al. 2011; Renaud et al. 2015), including the
clams, urchins, and mussels eaten by sea otters. Increases in ocean
temperatures and changes in sea ice may allow southern invertebrate
species to move northward and create more resource competition for
Arctic species. It is possible that Arctic species and overall species
richness may decline as a result of increasing ocean temperatures
(Renaud et al. 2015). However, there is a great deal of uncertainty and
variability in the predicted effects of increased ocean temperatures
and sea ice changes on benthic productivity (Post et al. 2013), and
these potential impacts are likely to vary throughout the sea otter's
range. Another potential concern with increased ocean temperatures is
elevated levels of biotoxins in bivalve mollusks associated with
harmful algal blooms (HABs) (Burek et al. 2008; Gulland et al. 2022; 88
FR 53510, August 8, 2023). Biotoxins bioaccumulate through trophic
levels to sea otters and other top-level predators when they consume
contaminated prey (Miller et al. 2010). Biotoxin exposure causes
lesions in the central nervous system and cardiovascular system of sea
otters (Miller et al. 2021), which can cause or contribute to
mortality. For example, biotoxin concentrations were detected in 29
percent of sea otters examined for causes of mortality, and HAB
toxicosis was considered the main cause of death for 2 of the 144 sea
otters examined (Burek-Huntington et al. 2021). It is not well
understood what impact HABs may have on the health of sea otter
populations that are exposed to and uptake biotoxins through prey
sources (88 FR 53510, August 8, 2023).
Climate change may also impact sea otter prey species through ocean
acidification. Ocean acidification increases as the atmospheric
concentrations of greenhouse gases rise. Clams, snails, and crabs,
which are prevalent in sea otter diets, contain calcium-based shells,
which may be corroded from ocean acidification. The early life stages
of some bivalves and gastropods are likely to be negatively affected
(Kroeker et al. 2013; 88 FR 53510, August 8, 2023), particularly the
broadcast spawners that have an extended pelagic larval phase. Some sea
otter prey species may be more tolerant, especially those that are
periodically exposed to acidified seawater under natural conditions.
Sea otters eat a variety of different benthic organisms (LaRoche et al.
2021), and this variability in their diet may provide some resiliency
against the changes in prey availability due to ocean acidification.
Climate change has the potential to impact sea otters by altering
species ranges and interactions, introducing novel pathogens, and
changing the availability, distribution, and quality of prey species.
However, there is a great deal of uncertainty and variability in the
predicted effects of climate change on sea otters and their prey
species. Sea otters also exhibit behavioral flexibility and diversity
in their prey consumption (LaRoche et al. 2021), which may allow them
to adapt to climate change effects. For example, sea otters show a high
degree of individuality and diversity in their diet and foraging
behavior that allow them to compete in an environment with limited food
resources (Tinker et al. 2008; LaRoche et al. 2021). Evidence shows
that sea otters may also be able to attenuate the effects of climate
change through top-down effects within their ecosystem. For example,
the rising ocean temperatures and ocean acidification parallel a
decline in skeletal density of Clathromorphum nereostratum, a red alga
found in kelp forests. This reduction in skeletal density makes the
algae more susceptible to lethal grazing by sea urchins. Sea otters
regulate sea urchin populations through prey consumption, which helps
maintain equilibrium within kelp forests and potentially mitigate the
effects of climate change within kelp forests (Rasher et al. 2020).
More information is needed to better understand how climate change
impacts sea otters and how sea otter populations respond to climate
change impacts.

Potential Impacts of the Specified Activities on Marine Mammals

Effects of Noise on Sea Otters

We characterize ``noise'' as sound released into the environment
from human activities that exceeds ambient levels or interferes with
normal sound production or reception by sea otters. The terms
``acoustic disturbance'' and ``acoustic harassment'' are disturbances
or harassment events resulting from noise exposure. Potential effects
of noise exposure are likely to depend on the distance of the sea otter
from the sound source, the level and intensity of sound the sea otter
receives, background noise levels, noise frequency, noise duration, and
whether the noise is pulsed or continuous. The actual noise level
perceived by individual sea otters will also depend on whether the sea
otter is above or below water and atmospheric and environmental
conditions. Temporary disturbance of sea otters or localized
displacement reactions are the most likely effects to occur from noise
exposure.

Sea Otter Hearing

Pile driving and marine construction activities produce sound
within the hearing range of sea otters. Controlled sound exposure
trials on southern sea otters (Enhydra lutris nereis) indicate that sea
otters can hear frequencies between 125 hertz (Hz) and 38 kilohertz
(kHz), with best sensitivity between 1.2 and 27 kHz (Ghoul and
Reichmuth 2014). Sea otters are more adept at aerial hearing and their
sensitivity is similar to that of terrestrial carnivores (Reichmuth and
Ghoul 2012; Ghoul and Reichmuth 2016; Zellmer et al. 2021). Aerial and
underwater audiograms for a captive adult male southern sea otter in
the presence of ambient noise suggest the sea otter's hearing was less
sensitive to high-frequency (greater than 22 kHz) and low-frequency
(less than 2 kHz) sound than that of terrestrial mustelids but was
similar to that of a California sea lion (Zalophus californianus).
However, the sea otter was still able to hear low-frequency sounds, and
the detection thresholds for sounds between 0.125 and 1 kHz were
between 116 and 101 decibels (dB), respectively. Dominant frequencies
of southern sea otter vocalizations are between 3 and 8 kHz, with some
energy extending above 60 kHz (McShane et al. 1995; Ghoul and Reichmuth
2012).
Exposure to high levels of sound may cause changes in behavior,
masking of communications, temporary or permanent changes in hearing
sensitivity, discomfort, and injury to marine mammals. Sea otters do
not rely on sound to orient themselves, locate prey, or communicate
under water; therefore, masking of communications by anthropogenic
noise is less of a concern than for other marine mammals. However, sea
otters, especially mothers and pups, do use sound for communication in
air (McShane et al. 1995), and sea otters may monitor underwater sound
to avoid predators (Davis et al. 1987).

Exposure Thresholds

Underwater Sounds
Noise exposure criteria for identifying underwater noise levels
capable of causing Level A harassment (injury) to marine mammal
species, including sea otters, have been established using the same
methods as those used by the

[[Page 26494]]

National Marine Fisheries Service (NMFS) (Southall et al. 2019). These
criteria are based on estimated levels of sound exposure capable of
causing a permanent shift in hearing sensitivity (i.e., a permanent
threshold shift (PTS) (NMFS 2018)). A PTS occurs when noise exposure
causes damage to hair cells within the inner ear system (Ketten 2012).
Although the effects of PTS are, by definition, permanent, PTS does not
equate to total hearing loss.
Sound exposure thresholds incorporate two metrics of exposure: the
peak level of instantaneous exposure likely to cause PTS, and the
cumulative sound exposure level (SEL<INF>CUM</INF>) during a 24-hour
period. They also include weighting adjustments for the sensitivity of
different species to varying frequencies. PTS-based injury criteria
were developed from theoretical extrapolation of observations of
temporary threshold shifts (TTS) detected in lab settings during sound
exposure trials (Finneran 2015). A TTS is a noise-induced threshold
shift in hearing sensitivity that fully recovers over time (Finneran
2015). Southall et al. (2019) developed TTS thresholds for sea otters,
which are included in the ``other marine carnivores'' category, of 188
dB SEL for impulsive sounds and 199 dB SEL for nonimpulsive sounds.
Based on these analyses, Southall et al. (2019) predict that PTS for
sea otters will occur at 232 dB peak or 203 dB SEL<INF>CUM</INF> for
impulsive underwater sound and 219 dB SEL for nonimpulsive (continuous)
underwater sound.
The NMFS (2018) criteria do not identify thresholds for avoidance
of Level B harassment. For pinnipeds (seals and sea lions), NMFS has
adopted a 160-dB threshold for Level B harassment from exposure to
impulsive noise and a 120-dB threshold for continuous noise (High
Energy Seismic Survey Team 1999; NMFS 2018). These thresholds were
developed from observations of mysticete (baleen) whales responding to
airgun operations (e.g., Malme et al. 1983; Malme and Miles 1983;
Richardson et al. 1986, 1995) and from equating Level B harassment with
noise levels capable of causing TTS in lab settings. Southall et al.
(2007, 2019) assessed behavioral response studies and found
considerable variability among pinnipeds. The authors determined that
exposures between approximately 90 to 140 dB generally do not appear to
induce strong behavioral responses from pinnipeds in water. However,
they found behavioral effects, including avoidance, become more likely
in the range between 120 and 160 dB, and most marine mammals showed
some, albeit variable, responses to sound between 140 and 180 dB. Wood
et al. (2012) adapted the approach identified in Southall et al. (2007)
to develop a probabilistic scale for marine mammal taxa at which 10
percent, 50 percent, and 90 percent of individuals exposed are assumed
to produce a behavioral response. For many marine mammals, including
pinnipeds, these response rates were set at sound pressure levels
(SPLs) of 140, 160, and 180 dB, respectively.
We have evaluated these thresholds and determined that the Level B
harassment threshold of 120 dB for nonimpulsive noise is not applicable
to sea otters. The 120-dB threshold is based on studies in which gray
whales (Eschrichtius robustus) were exposed to experimental playbacks
of industrial noise (Malme et al. 1983; Malme and Miles 1983). During
these playback studies, southern sea otter responses to industrial
noise were also monitored (Riedman 1983, 1984). While gray whales
exhibited avoidance to industrial noise at the 120-dB threshold, there
was no evidence of disturbance reactions or avoidance in southern sea
otters. Thus, given the different range of frequencies to which sea
otters and gray whales are sensitive, the NMFS 120-dB threshold based
on gray whale behavior is not appropriate for predicting sea otter
behavioral responses, particularly for low-frequency sound.
Based on the lack of sea otter disturbance response or any other
reaction to the playback studies from the 1980s, as well as the absence
of a clear pattern of disturbance or avoidance behaviors attributable
to underwater sound levels up to about 160 dB resulting from low-
frequency broadband noise, we assume 120 dB is not an appropriate
behavioral response threshold for sea otters exposed to continuous
underwater noise.
Based on the best available scientific information about sea otters
and closely related marine mammals when sea otter data are limited, the
FWS has set 160 dB of received underwater sound as a threshold for take
by Level B harassment of sea otters in this proposed ITR. Exposure to
in-water noise levels between 125 Hz and 38 kHz that are greater than
160 dB--for both impulsive and nonimpulsive sound sources--will be
considered by the FWS as Level B harassment. Thresholds for Level A
harassment (which entails the potential for injury) for in-water noise
levels between 125 Hz and 38 kHz are 232 dB peak or 203 dB SEL for
impulsive sounds and 219 dB SEL for continuous sounds (table 4).
Airborne Sounds
The NMFS (2018) guidance neither addresses thresholds for
preventing injury or disturbance from airborne noise, nor provides
thresholds for avoidance of Level B harassment. Conveyance of
underwater noise into the air is of little concern since the effects of
pressure release and interference at the water's surface reduce
underwater noise transmission into the air. For activities that create
both in-air and underwater noise, we will estimate take based on
parameters for underwater noise transmission. Considering sound energy
travels more efficiently through water than through air, this
estimation will also account for exposures to sea otters at the
surface.

Table 4--Temporary Threshold Shift (TTS) and Permanent Threshold Shift (PTS) Thresholds
[Established by Southall et al. (2019) through modeling and extrapolation for ``Other Marine Carnivores,'' which include sea otters.*]
--------------------------------------------------------------------------------------------------------------------------------------------------------
TTS PTS
-----------------------------------------------------------------------------------------------
Nonimpulsive Impulsive Nonimpulsive Impulsive
-----------------------------------------------------------------------------------------------
SELCUM SELCUM Peak SPL SELCUM SELCUM Peak SPL
--------------------------------------------------------------------------------------------------------------------------------------------------------
Air..................................................... 157 146 170 177 161 176
Water................................................... 199 188 226 219 203 232
--------------------------------------------------------------------------------------------------------------------------------------------------------
* Values are weighted for other marine carnivores' hearing thresholds and given in cumulative sound exposure level (SELCUM dB re (20 micropascal
([micro]Pa) in air and SELCUM dB re 1 [micro]Pa in water) for impulsive and nonimpulsive sounds, and unweighted peak sound pressure level (SPL) in air
(dB re 20[micro]Pa) and water (dB 1[micro]Pa) (impulsive sounds only).

[[Page 26495]]

Evidence From Sea Otter Studies

Sea otters may be more resistant to the effects of acoustic
disturbance and human activities than other marine mammals. For
example, observers have noted no changes from southern sea otters in
regard to their presence, density, or behavior in response to
underwater sounds from industrial noise recordings at 110 dB and a
frequency range of 50 Hz to 20 kHz and airguns, even at the closest
distance of 0.5 nautical miles (<1 km or 0.6 mi) (Riedman 1983).
Southern sea otters did not respond noticeably to noise from a single
1,638 cubic centimeters (cm\3\) (100 cubic inches [in\3\]) airgun, and
no sea otter disturbance reactions were evident when a 67,006-cm\3\
(4,089-in\3\) airgun array was as close as 0.9 km (0.6 mi) to sea
otters (Riedman 1983, 1984). However, southern sea otters displayed
slight reactions to airborne engine noise (Riedman 1983). Northern sea
otters were observed to exhibit a limited response to a variety of
airborne and underwater sounds, including a warble tone, sea otter pup
calls, calls from killer whales (Orcinus orca) (which are predators to
sea otters), air horns, and an underwater noise harassment system
designed to drive marine mammals away from crude oil spills (Davis et
al. 1988). These sounds elicited reactions from northern sea otters,
including startle responses and movement away from noise sources.
However, these reactions were observed only when northern sea otters
were within 100 to 200 m (328 to 656 ft) of noise sources. Further,
northern sea otters appeared to become habituated to the noises within
2 hours or, at most, 3 to 4 days (Davis et al. 1988).
Noise exposure may be influenced by the amount of time sea otters
spend at the water's surface. Noise at the water's surface can be
attenuated by turbulence from wind and waves more quickly compared to
deeper water, reducing potential noise exposure (Greene and Richardson
1988; Richardson et al. 1995). Additionally, turbulence at the water's
surface limits the transference of sound from water to air. A sea otter
with its head above water will be exposed to only a small fraction of
the sound energy traveling through the water beneath it. The average
amount of time that sea otters spend above the water each day while
resting and grooming varies between males and females and across
seasons (Esslinger et al. 2014; Zellmer et al. 2021). For example,
female sea otters foraged for an average of 8.78 hours per day compared
to male sea otters, which foraged for an average of 7.85 hours per day
during the summer months (Esslinger et al. 2014). Sea otters spend an
average of 63 to 67 percent of their day at the surface resting and
grooming during the summer months (Esslinger et al. 2014). Few studies
have evaluated foraging times during the winter months. Garshelis et
al. (1986) found that foraging times increased from 5.1 hours per day
to 16.6 hours per day in the winter; however, Gelatt et al. (2002) did
not find a significant difference in seasonal foraging times. It is
likely that seasonal variation is determined by seasonal differences in
energetic demand and the quality and availability of prey sources
(Esslinger et al. 2014). These results suggest that the large portion
of the day that sea otters spend at the surface may help limit sea
otters' exposure during noise-generating operations.
Sea otter sensitivity to industrial activities may be influenced by
the overall level of human activity within the sea otter population's
range. In locations that lack frequent human activity, sea otters
appear to have a lower threshold for disturbance (Benham 2006). Sea
otters in Alaska exhibited escape behaviors in response to the presence
and approach of vessels (Udevitz et al. 1995). Behaviors included
diving or actively swimming away from a vessel, entering the water from
haulouts, and disbanding groups with sea otters swimming in multiple
different directions (Udevitz et al. 1995). Sea otters in Alaska were
also observed to avoid areas with heavy vessel traffic in the summer
and return to these areas during seasons with less vessel traffic
(Garshelis and Garshelis 1984). In Cook Inlet, sea otters drifting on a
tide trajectory that would have taken them within 500 m (0.3 mi) of an
active offshore drilling rig were observed to swim in order to avoid a
close approach of the drilling rig despite near-ambient noise levels
(BlueCrest 2013).
Individual sea otters in the Seward, Sitka, and Kodiak areas will
likely show a range of responses to noise from pile-driving activities.
Some sea otters will likely dive, show startle responses, change
direction of travel, or prematurely surface. Sea otters reacting to
pile-driving activities may divert time and attention from biologically
important behaviors, such as feeding and nursing pups. Sea otter
responses to disturbance can result in energetic costs. For example,
sea otters spend more time traveling in areas with high levels of
disturbance (Curland 1997). Higher energetic costs require increased
amounts of prey consumption (Barrett 2019). This increased prey
consumption may impact sea otter prey availability and cause sea otters
to spend more time foraging and less time resting (Barrett 2019). Some
sea otters may abandon the project area and return when the disturbance
has ceased. Based on the observed movement patterns of sea otters
(Lensink 1962; Kenyon 1969, 1981; Garshelis and Garshelis 1984; Riedman
and Estes 1990), we expect some sea otters will respond to pile-driving
activities by dispersing to nearby areas of suitable habitat; however,
other sea otters, especially territorial adult males, will not be
displaced.

Consequences of Permanent Threshold Shift

Sea otters exposed to noise levels above Level A harassment
threshold criteria may experience a permanent shift in the sensitivity
of their hearing. This shift would cause the sea otter to be
permanently unable to hear sounds at frequencies similar to those that
caused the initial injury. Pile driving and marine construction
activities are typically low-frequency (e.g., less than 2 kHz), thus
sea otters may lose their ability to hear low-frequency sounds as a
result of exposure to noise levels above Level A harassment thresholds.
However, the injury is not anticipated to result in total hearing loss.
We do not anticipate that a reduction in hearing sensitivity would
significantly affect a sea otter's health, reproduction, or survival or
otherwise cause any population-level effects. The potential effects of
repeated exposure to noise levels above Level A harassment thresholds
may include a greater reduction in a sea otter's hearing sensitivity if
the sea otter is exposed to different sound frequencies that can cause
PTS. While sea otters do not rely on sound to orient themselves, locate
prey, or communicate under water, mothers and pups do use sound for
communication in air (McShane et al. 1995), and sea otters may monitor
underwater sound to avoid predators (Davis et al. 1987). However, we
anticipate that a sea otter will retain the majority of its hearing
range if it experiences PTS from multiple Level A harassment noise
exposures and that impacts from PTS will not have long-term
consequences to a sea otter's survival and reproduction. Therefore, we
do not anticipate impacts to sea otters' ability to move, forage, or
communicate as a result of PTS from one or multiple Level A harassment
noise exposures. We also anticipate that sea otters will move away from
Level A harassment zones to avoid experiencing PTS.

[[Page 26496]]

Consequences of Disturbance

The reactions of wildlife to disturbance can range from short-term
behavioral changes to long-term impacts that affect survival and
reproduction. When disturbed by noise, animals may respond behaviorally
(e.g., escape response) or physiologically (e.g., increased heart rate,
hormonal response) (Harms et al. 1997; Tempel and Guti[eacute]rrez
2003). Theoretically, the energy expense and associated physiological
effects from repeated disturbance could ultimately lead to reduced
survival and reproduction (Gill and Sutherland 2000; Frid and Dill
2002). For example, South American sea lions (Otaria byronia) visited
by tourists exhibited an increase in the state of alertness and a
decrease in maternal attendance and resting time on land, thereby
potentially reducing population size (Pavez et al. 2015). In another
example, killer whales that lost feeding opportunities due to vessel
traffic faced a substantial (18 percent) estimated decrease in energy
intake (Williams et al. 2002). In severe cases, such disturbance
effects can have population-level consequences. For example, increased
disturbance by tourism vessels has been associated with a decline in
abundance of bottlenose dolphins (Tursiops spp.) (Bejder et al. 2006;
Lusseau et al. 2006). However, these examples evaluated sources of
disturbance that were longer term and more consistent than the
temporary and intermittent nature of the specified project activities.
These examples illustrate direct effects on survival and
reproductive success, but disturbances can also have indirect effects.
Response to acoustic disturbance is considered a nonlethal stimulus
that is similar to an antipredator response (Frid and Dill 2002). Sea
otters are susceptible to predation, particularly from killer whales
and eagles, and have a well-developed antipredator response to
perceived threats. For example, the presence of a harbor seal (Phoca
vitulina) did not appear to disturb southern sea otters, but they
demonstrated a fear response in the presence of a California sea lion
by actively looking above and beneath the water (Limbaugh 1961).
Although an increase in vigilance or a flight response is
nonlethal, a tradeoff occurs between risk avoidance and energy
conservation. An animal's reactions to acoustic disturbance may cause
stress and direct an animal's energy away from fitness-enhancing
activities such as feeding and mating (Frid and Dill 2002; Goudie and
Jones 2004). For example, southern sea otters in areas with heavy
recreational vessel traffic demonstrated changes in behavioral time
budgeting, showing decreased time resting and changes in haulout
patterns and distribution (Benham 2006; Maldini et al. 2012). Chronic
stress can also lead to weakened reflexes, lowered learning responses
(Welch and Welch 1970; van Polanen Petel et al. 2006), compromised
immune function, decreased body weight, and abnormal thyroid function
(Selye 1979).
Changes in behavior resulting from anthropogenic disturbance can
include increased agonistic interactions between individuals or
temporary or permanent abandonment of an area (Barton et al. 1998).
Additionally, the extent of previous exposure to humans (Holcomb et al.
2009), the type of disturbance (Andersen et al. 2012), and the age or
sex of the individuals (Shaughnessy et al. 2008; Holcomb et al. 2009)
may influence the type and extent of response in individual sea otters.

Vessel Activities

Vessel collisions with marine mammals can result in death or
serious injury. Wounds resulting from vessel strike may include massive
trauma, hemorrhaging, broken bones, or propeller lacerations (Knowlton
and Kraus 2001). An animal may be harmed by a vessel when the vessel
runs over the animal at the surface, the animal hits the bottom of a
vessel while the animal is surfacing, or the animal is cut by a
vessel's propeller.
Mortality associated with vessel strike has been determined based
on recovery of carcasses with lacerations indicative of propeller
injuries (Wild and Ames 1974; Morejohn et al. 1975). Studies have shown
that trauma-related injuries, such as those caused by vessel strikes,
were a common cause of mortality in northern sea otters (White et al.
2018; Burek-Huntington et al. 2021). Based on necropsy results from sea
otters in Alaska, trauma was found to be the cause of death in ~4
percent (65 of 1,474 sea otter necropsies from 1996 to 2019) and ~16
percent (128 of 780 sea otter necropsies from 2002 to 2012) (USFWS
2020; Burek-Huntington et al. 2021). Necropsies of sea otters in which
trauma was determined to be the ultimate cause of death show that
disease or biotoxin exposure can be a contributing factor, which
incapacitated the sea otter and made it more vulnerable to vessel
strike (Burek-Huntington et al. 2021; 88 FR 53510, August 8, 2023).
Vessel speed influences the likelihood of vessel strikes involving
sea otters. The probability of death or serious injury to a marine
mammal increases as vessel speed increases (Laist et al. 2001;
Vanderlaan and Taggart 2007). Sea otters spend a considerable portion
of their time at the water's surface (Esslinger et al. 2014). They are
typically visually aware of approaching vessels and can move away if a
vessel is not traveling too quickly. Mitigation measures to be applied
to vessel operations to prevent collisions or interactions are included
below in the proposed regulations in Sec. 18.107 Mitigation.
Sea otters exhibit behavioral flexibility in response to vessels,
and their responses may be influenced by the intensity and duration of
the vessel's activity. For example, sea otter populations in Alaska
were observed to avoid areas with heavy vessel traffic but return to
those same areas during seasons with less vessel traffic (Garshelis and
Garshelis 1984). Sea otters have also shown signs of disturbance or
escape behaviors in response to the presence and approach of survey
vessels including sea otters diving and/or actively swimming away from
a vessel, sea otters on haulouts entering the water, and groups of sea
otters disbanding and swimming in multiple different directions
(Udevitz et al. 1995).
Additionally, responses to vessels may be influenced by the
individual sea otter's previous experience with vessels. Groups of
southern sea otters in two locations in California showed markedly
different responses to kayakers approaching to specific distances,
suggesting a different level of tolerance between the groups (Gunvalson
2011). Benham (2006) found evidence that the sea otters exposed to high
levels of recreational activity may have become more tolerant than
individuals in less disturbed areas. Sea otters off the California
coast showed only mild interest in vessels passing within hundreds of
meters and appeared to have habituated to vessel traffic (Riedman 1983;
Curland 1997). These results indicate that sea otters may adjust their
responses to vessel activities depending on the level of activity.
Vessel activity for the work in Seward may include the use of
barges within the SMIC boat basin to stage equipment and materials as
necessary. Protected Species Observers (PSOs) may also be stationed on
a barge or in a small vessel to monitor for marine mammals and
implement mitigation measures. Vessels will not be used extensively or
over a long duration during project activities in Seward. Vessel
operations for project activities in Sitka and Kodiak may include
transportation of personnel,

[[Page 26497]]

supplies, and equipment via barges, tugs, and skiffs. Vessels will be
used each day of project activities to transport personnel and
equipment between land and the construction barge and to support
construction operations. We do not anticipate that sea otters will
experience changes in behavior indicative of harassment during vessel
operations. Additionally, vessel operators for all projects would take
every precaution to avoid harassment of sea otters when a vessel is
operating near sea otters and implement mitigation measures described
below in the proposed regulations in Sec. 18.107 Mitigation.

Effects on Sea Otter Habitat and Prey

Physical and biological features of habitat essential to the
conservation of sea otters include the benthic invertebrates eaten by
sea otters, shallow rocky areas, and kelp (e.g., bull kelp (Nereocystis
luetkeana) and dragon kelp (Eualaria fistulosa)) beds that provide
cover from predators. Sea otter habitat in the project area includes
coastal areas within the 40-m (131-ft) depth contour where high
densities of sea otters have been detected (Riedman and Estes 1990;
Tinker et al. 2019; 88 FR 53510, August 8, 2023).
Industrial activities, such as pile driving and marine
construction, may generate in-water noise at levels that can
temporarily displace sea otters from important habitat containing sea
otter prey species. The primary prey species for sea otters are sea
urchins (Strongylocentrotus spp. and Mesocentrotus spp.), abalone
(Haliotis spp.), clams (e.g., Clinocardium nuttallii, Leukoma staminea,
and Saxidomus gigantea), mussels (Mytilus spp.), crabs (e.g.,
Metacarcinus magister, Pugettia spp., Telemessus cheiragonus, and
Cancer spp.), and squid (Loligo spp.) (LaRoche et al. 2021). When
preferred prey are scarce, sea otters will also eat kelp, slow-moving
benthic fishes, sea cucumbers (e.g., Apostichopus californicus), egg
cases of rays, turban snails (Tegula spp.), octopuses (e.g., Octopus
spp.), barnacles (Balanus spp.), sea stars (e.g., Pycnopodia
helianthoides), scallops (e.g., Patinopecten caurinus), rock oysters
(Saccostrea spp.), worms (e.g., Eudistylia spp.), and chitons (e.g.,
Mopalia spp.) (Riedman and Estes 1990; Davis and Bodkin 2021). Sea
otters eat a variety of benthic organisms (LaRoche et al. 2021), and
this variability in their diet may provide some resiliency against the
impacts of habitat displacement.
Noise may also affect benthic invertebrates (Tidau and Briffa 2016;
Carroll et al. 2017). Behavioral changes, such as an increase in
lobster (Homanus americanus) feeding levels (Payne et al. 2007), an
increase in avoidance behavior by wild-caught captive reef squid
(Sepioteuthis australis) (Fewtrell and McCauley 2012), and deeper
digging by razor clams (Sinonovacula constricta) (Peng et al. 2016)
have been observed following experimental exposures to sound. Physical
changes have also been observed in response to increased sound levels,
including changes in serum biochemistry and hepatopancreatic cells in
lobsters (Payne et al. 2007) and long-term damage to the statocysts
required for hearing in several cephalopod species (Andr[eacute] et al.
2011; Sol[eacute] et al. 2013, 2019). De Soto et al. (2013) found
impaired embryonic development in scallop (Pecten novaezelandiae)
larvae when exposed to 160 dB. Christian et al. (2003) noted a
reduction in the speed of egg development of bottom-dwelling crabs
following exposure to noise; however, the sound level (221 dB at 2 m or
6.6 ft) was far higher than the proposed project activities will
produce. Industrial noise can also impact larval settlement by masking
the natural acoustic settlement cues for crustaceans and fish (Pine et
al. 2012; Simpson et al. 2016; Tidau and Briffa 2016).
While these studies provide evidence of deleterious effects to
invertebrates as a result of increased sound levels, Carroll et al.
(2017) caution that there is a wide disparity between results obtained
in field and laboratory settings. In experimental settings, changes
were observed only when animals were housed in enclosed tanks, and many
were exposed to prolonged bouts of continuous, pure tones. We would not
expect similar results in open marine conditions. It is unlikely that
noises generated by project activities will have any lasting effect on
sea otter prey given the short-term duration of noise produced by each
component of the proposed work.
Noise-generating activities that interact with the seabed can
produce vibrations, resulting in the disturbance of sediment and
increased turbidity in the water. Although turbidity is likely to have
little impact on sea otters and prey species (Todd et al. 2015), there
may be some impacts from vibrations and increased sedimentation. For
example, mussels (Mytilus edulis) exhibited changes in valve gape and
oxygen demand, and hermit crabs (Pagurus bernhardus) exhibited limited
behavioral changes in response to vibrations caused by pile driving
(Roberts et al. 2016). Increased sedimentation is likely to reduce sea
otter visibility, which may result in reduced foraging efficiency and a
potential shift to less-preferred prey species. These outcomes may
cause sea otters to spend more energy on foraging or processing the
prey items; however, the impacts of a change in energy expenditure are
not likely seen at the population level (Newsome et al. 2015).
Additionally, the benthic invertebrates may be impacted by increased
sedimentation, resulting in higher abundances of opportunistic species
that recover quickly from industrial activities that increase
sedimentation (Kotta et al. 2009). Although sea otter foraging could be
impacted by industrial activities that cause vibrations and increased
sedimentation, it is more likely that sea otters would be temporarily
displaced from the project area due to impacts from noise rather than
vibrations and sedimentation.
Work in Seward is expected to be completed in less than 1 year and
there are only 22 days of in-water work planned. We anticipate that any
displacement of sea otters due to project activities will be temporary
and short term and any potential impacts to sea otter prey species and
habitat will be limited. In Sitka, 117 days of work will be spread
across a single year. We anticipate that any displacement of sea otters
and potential impacts to sea otter prey and habitat due to project
activities in Sitka will be temporary, short-term, and limited. If
displacement of sea otters and potential impacts to sea otter prey and
habitat are more than short-term and limited, we would expect them to
be similar in nature but smaller in magnitude than those described for
Kodiak.
Project activities in Kodiak would occur across multiple years. If
sea otters are displaced for multiple years due to project activities
in the area, this long-term displacement may impact sea otter prey
species and habitat. Sea otter predation generally reduces the density
and size of invertebrate prey species in the area and maintains an
equilibrium of biodiversity in nearshore habitats (Coletti 2021).
Removal of sea otters may result in a range of effects to nearshore
habitats and prey species. These effects may range from limited to
substantial changes and are dependent on a variety of factors in the
nearshore ecosystem such as sea otter density, occupation time, and
prey species recruitment rates. For example, following an approximate
90 percent decline in sea otter populations in the Aleutian
archipelago, sea urchins experienced an eightfold increase in biomass
and kelp density declined by nearly 90 percent across 10 years (Estes

[[Page 26498]]

et al. 1998). Conversely, sea urchin biomass and kelp abundance
experienced little to no change in response to the sea otter
populations declining by approximately 50 percent across 9 years in PWS
and approximately 70 percent across 10 years at the Semichi Islands
(Dean et al. 2000; Konar 2000).

Potential Impacts of the Specified Activities on Subsistence Uses

The specified activities will occur near marine subsistence harvest
areas used by Alaska Natives surrounding the USCG facilities in Seward,
Sitka, and Kodiak. Table 5 shows the number of sea otters taken by
subsistence hunting between 2013 and 2023 in the communities where the
specified activities would occur.

Table 5--Sea Otters: Subsistence Hunting Totals and Average Number Harvested per Year
[Seward, Sitka, and Kodiak, AK, 2013 through 2023]
--------------------------------------------------------------------------------------------------------------------------------------------------------
Average
(rounded to
Location 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 Total nearest
whole
number)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Seward......................... 0 0 0 0 0 0 0 0 0 0 2 2 0
Sitka.......................... 539 354 325 356 340 160 229 85 139 127 184 2,838 258
Kodiak......................... 34 52 21 103 31 10 58 34 56 37 27 463 42
--------------------------------------------------------------------------------------------------------------------------------------------------------

No subsistence harvest of sea otters was documented in Seward from
2013 through 2022, and only two sea otters were harvested in 2023.
Sitka has a consistently high level of subsistence harvest activity
and harvest locations frequently range up to ~48 km (30 mi) from Sitka
and throughout Sitka Sound. Although some harvest activity takes place
within a few miles of the city, the anticipated effects from the USCG's
work are constrained to Sitka Channel, which does not see harvest
activity or hunting effort.
Subsistence harvest of sea otters around Kodiak Island takes place
primarily in Whale Pass, Womens Bay, Whale Passage, and Kizhuyak Bay
with totals of 81, 61, 37, and 34 sea otters taken, respectively, from
2013 through 2023.
As all three work sites are active USCG facilities, the proposed
project does not overlap with current subsistence harvest areas.
Construction activities will not preclude access to hunting areas or
interfere in any way with individuals wishing to hunt. Furthermore, the
USCG facilities are within developed areas and city limits, where
firearm use is prohibited. Despite no conflict with subsistence use
being anticipated, the FWS will be conducting outreach with potentially
affected communities to see whether there are any questions, concerns,
or potential conflicts regarding subsistence use in those areas. If any
conflicts are identified in the future, the USCG will develop a plan of
cooperation specifying the particular steps necessary to minimize any
effects the project may have on subsistence harvest.

Estimated Take

Definitions of Incidental Take Under the MMPA

Under the MMPA, ``take'' means ``to harass, hunt, capture, or kill,
or attempt to harass, hunt, capture, or kill any marine mammal'' (16
U.S.C. 1362(13)). Below we provide definitions of three potential types
of take of sea otters. The FWS does not anticipate and is not proposing
to authorize lethal take as a part of the proposed rule; however, the
definitions of these take types are provided for context and
background.
Lethal Take
In the most serious interactions, human actions can result in the
mortality of sea otters, which we define here as lethal take.
Level A Harassment
The MMPA defines Level A harassment, for nonmilitary readiness
activities, as ``any act of pursuit, torment, or annoyance which . . .
has the potential to injure a marine mammal or marine mammal stock in
the wild'' (16 U.S.C. 1362(18)(A)(i), (C)). We interpret this
definition to include human activity that may result in the injury of
sea otters.
Level B Harassment
The MMPA defines Level B harassment for nonmilitary readiness
activities as ``any act of pursuit, torment, or annoyance which . . .
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, feeding, or sheltering''
(16 U.S.C. 1362(18)(A)(ii), (D)). We interpret this definition to
include human-caused reactions that disrupt biologically significant
behaviors or activities for the affected animal. Such reactions
include, but are not limited to, the following:
<bullet> Swimming away at a fast pace on belly (i.e., porpoising);
<bullet> Repeatedly raising the head vertically above the water to
get a better view (spyhopping) while apparently agitated or while
swimming away;
<bullet> In the case of a pup, repeatedly spyhopping while hiding
behind and holding onto its mother's head;
<bullet> Abandoning prey or feeding area;
<bullet> Ceasing to nurse and/or rest (applies to dependent pups);
<bullet> Ceasing to rest (applies to independent animals);
<bullet> Ceasing to use movement corridors;
<bullet> Ceasing mating behaviors;
<bullet> Shifting/jostling/agitation in a raft (i.e., group of 10
or more sea otters) so that the raft disperses;
<bullet> Sudden diving of an entire raft; or
<bullet> Flushing animals off a haulout.
This list does not encompass all possible behaviors that indicate
Level B harassment; other behavioral responses may be indicative of
take by Level B harassment. Relatively minor changes in behavior such
as the animal raising its head or temporarily changing its direction of
travel are not likely to disrupt biologically important behavioral
patterns, and the FWS does not view such minor changes in behavior as
indicative of a take by Level B harassment. It is also important to
note that eliciting behavioral responses that equate to take by Level B
harassment repeatedly may result in Level A harassment.

Calculating Take

Sea Otter Density
We assumed all sea otters exposed to underwater sound levels that
meet the acoustic exposure criteria defined above in Exposure
Thresholds will experience take by Level A harassment or Level B

[[Page 26499]]

harassment. We refer to the area in which sound levels meet or exceed
the acoustic exposure criteria defined for either Level A harassment or
Level B harassment as the ensonification area. For each project,
spatially explicit ensonification areas were established around the
planned construction location to estimate the number of sea otters that
may be exposed to these sound levels. For Seward, we determined the
number of sea otters present in the ensonification areas using density
information generated by Weitzman and Esslinger (2015). The density of
sea otters (2.31 sea otters/km\2\) was derived from surveys conducted
of PWS (Weitzman and Esslinger 2015).
Recent estimates of the number of sea otters in the Sitka project
area are less than 1 sea otter/km\2\. Tinker et al. (2019) estimated an
average of 0.85 sea otters/km\2\ in the subregion that includes the
project area (N05). Similarly, fine-scale ecological diffusion models
have estimated 0.062 sea otters/km\2\ inside the harbor breakwater and
0.65 sea otters/km\2\ outside the harbor breakwater (Eisaguirre et al.
2021). We used the largest estimated sea otter density of 0.85 sea
otters/km\2\ to conservatively estimate the number of sea otters
potentially affected by project activities at Sitka.
For project activities in Kodiak, we determined the number of sea
otters present in the ensonification areas using a localized sea otter
density estimate derived from sea otter observation data to account for
potentially large sea otter groups. Increased numbers of sea otters
were observed in Womens Bay, where project activities in Kodiak would
occur, during the most recent sea otter abundance survey of the Kodiak
Archipelago in 2014 (Cobb 2018). Additionally, large group sizes of up
to 159 sea otters were observed in Womens Bay (Cobb 2018).
To account for the potential presence of large sea otter groups in
the Kodiak project area, we determined the number of sea otters
expected to be present in the Kodiak project area by analyzing sea
otter observation data collected during a dock improvement project at
the Kodiak Ferry Terminal from November 2015 to June 2016 (ABR 2016).
The Kodiak Ferry Terminal project area is approximately 8 km (5 mi)
from the Kodiak project area. Observers monitored for marine mammals at
various periods throughout the day, and some days had multiple
observers at different observation stations. Marine mammals were
monitored for 110 days, and sea otters were observed on 100 days. We
calculated a daily sea otter count at each observation station for each
observation day by summing the maximum sea otter group size for each
observation recorded within a given day at that station. Maximum group
size ranged from 0 to 218 sea otters. Daily sea otter counts ranged
from 0 to 423 sea otters.
To obtain consistent and comparable measures for each observation
station, we calculated the total area in which sea otters were observed
by drawing a minimum convex polygon around the spatial extent of all
sea otter locations observed at an observation station. The daily sea
otter counts were then divided by the respective total area of
observation for the station at which it was observed, resulting in a
measure of sea otters per square kilometer. This resulting density will
be biased higher than actual densities because the actual observed area
is larger than the minimum convex polygon around the observed sea otter
locations, but this conservative assumption will avoid underestimating
potential disturbance to sea otters during project activities. On days
with observations conducted at multiple observation stations, we
calculated the average sea otter density for those observation stations
to get a single sea otter density on that day. We averaged all daily
sea otter densities to obtain 51.81 sea otters/km\2\ per day to
represent the average number of sea otters anticipated in the Kodiak
project area.
Sound Levels for the Specified Activities
The project activities at each of the three locations consist of
multiple possible methods of pile removal (vibratory pile extraction,
pile clipping, and use of a diamond wire saw, hydraulic chain saw or
hydraulic shearing device) and multiple methods of pile installation
(DTH rock socket drilling, vibratory pile settling, and impact pile
proofing). Each of these methods will generate a different type of in-
water noise. Vibratory pile extraction and settling, pile clipping, and
use of a diamond wire saw, hydraulic chain saw, or hydraulic shearing
device will produce nonimpulsive or continuous noise; impact pile
proofing will produce impulsive noise; and rock socket DTH drilling is
considered to produce both impulsive and continuous noise (NMFS 2020).
The level of sound anticipated from each project component was
established using recorded data from several sources in addition to
guidance from NMFS. We used the empirical data from those proxy
projects and sound levels provided by NMFS with the NMFS Technical
Guidance and User Spreadsheet (NMFS 2018, 2020) to determine the
distance at which sound levels would attenuate to Level A harassment
thresholds (table 4). To estimate the distances at which sounds would
attenuate to Level B harassment thresholds (table 4), we used the data
from the proxy projects and the sound levels provided by NMFS with the
NMFS-recommended transmission loss coefficient of 15 for coastal pile-
driving activities in a practical spreading loss model (NMFS 2020) to
determine the distance at which sound levels attenuate to 160 dB re 1
[mu]Pa. The weighting factor adjustment included in the NMFS user
spreadsheet accounts for sounds created in portions of an animal's
hearing range where they have less sensitivity. We used the weighting
factor adjustment for otariid pinnipeds as they are the closest
available physiological and anatomical proxy for sea otters. The
spreadsheet also incorporates a transmission loss coefficient, which
accounts for the reduction in sound level outward from a sound source.
Sound levels for all sources are unweighted and given in dB re 1
[mu]Pa. Nonimpulsive sounds are in the form of mean maximum root mean
square (RMS) SPL as it is more conservative than SEL<INF>CUM</INF> or
peak SPL for these activities. Impulsive sound sources are in the form
of SEL for a single strike (SELss). Sound levels for project activities
in Seward, Sitka, and Kodiak are listed in tables 6, 7, and 8,
respectively.

[[Page 26500]]

Table 6--USCG Moorings Seward: Project Activities; Sound Types, Levels, and Timing
--------------------------------------------------------------------------------------------------------------------------------------------------------
Timing per pile
(nonimpulsive
Pile size and sound sources) or
Project component material Activity Type of sound Sound levels Source strikes per pile
(impulsive sound
sources)
--------------------------------------------------------------------------------------------------------------------------------------------------------
FRC Moorings.................... <40.6-cm (<16-in) Removal--vibratory Nonimpulsive...... 160 dB RMS........ 89 FR 60359....... 30 minutes.
steel.
Removal--pile 161.2 dB RMS...... NAVFAC \a\ SW 2020 10.4 minutes.
clipper.
Removal--diamond 161.5 dB RMS...... NAVFAC \a\ SW 2020 15.5 minutes.
wire saw.
76.2-cm (30-in) Installation--rock Both impulsive and 174 dB RMS; 164 dB NMFS 2022......... 180 minutes/
concrete or steel. socket DTH. nonimpulsive. SELss; 194 dB 108,000 strikes.
peak.
Installation--vibr Nonimpulsive...... 163 dB RMS........ NAVFAC \a\ SW 2020 10 minutes.
atory settling.
Installation--impa Impulsive......... 186 dB RMS; 173 dB 89 FR 60359....... 5 strikes.
ct proofing. SELss; 198 dB
peak.
New Dock........................ 76.2-cm (30-in) Installation--rock Both impulsive and 174 dB RMS; 164 dB NMFS 2022......... 180 minutes/
concrete or steel. socket DTH. nonimpulsive. SELss; 194 dB 108,000 strikes.
peak.
Installation--vibr Nonimpulsive...... 163 dB RMS........ NAVFAC \a\ SW 2020 10 minutes.
atory settling.
Installation--impa Impulsive......... 186 dB RMS; 173 dB 89 FR 60359....... 5 strikes.
ct proofing. SELss; 198 dB
peak.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Naval Facilities Engineering Command.

Table 7--USCG Moorings Sitka: Project Activities; Sound Types, Levels, and Timing
--------------------------------------------------------------------------------------------------------------------------------------------------------
Timing per pile
(nonimpulsive
Pile size and sound sources) or
Project component material Activity Type of sound Sound levels Source strikes per pile
(impulsive sound
sources)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Demolition...................... 76.2-cm (30-in) Removal--vibratory Nonimpulsive...... 162 dB RMS........ Caltrans 2020..... 30 minutes.
concrete.
Removal--pile 161.2 dB RMS...... NAVFAC \a\ SW 2020 10.4 minutes.
clipper.
Removal--diamond 161.5 dB RMS...... NAVFAC \a\ SW 2020 15.5 minutes.
wire saw.
35.6-cm (14-in) Removal--vibratory Nonimpulsive...... 160 dB RMS........ Greenbusch 2018... 10 minutes.
timber.
Construction.................... 76.2-cm (30-in) Installation--rock Both impulsive and 174 dB RMS; 164 dB NMFS 2022......... 180 minutes/
concrete or steel. socket DTH. nonimpulsive. SELss; 194 dB 108,000 strikes.
peak.
Installation--vibr Nonimpulsive...... 163 dB RMS........ NAVFAC \a\ SW 2020 10 minutes.
atory settling.
Installation--impa Impulsive......... 186 dB RMS; 173 dB 89 FR 60359....... 5 strikes.
ct proofing. SELss; 198 dB
peak.
Construction.................... 35.6-cm (14-in) Installation--impa Impulsive......... 170 dB RMS; 164 dB Caltrans 2020..... 100 strikes.
timber. ct driving. SELss.
Construction.................... 33.0-cm (13-in) Installation--impa Impulsive......... 153 dB RMS; 162 dB Caltrans 2020..... 160 strikes.
composite. ct driving. SELss.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Naval Facilities Engineering Command.

Table 8--USCG Base Kodiak: Project Activities; Sound Types, Levels, and Timing
--------------------------------------------------------------------------------------------------------------------------------------------------------
Timing per pile
(nonimpulsive sound
Project component Year Pile size and Activity Type of sound Sound levels Source sources) or strikes
material per pile (impulsive
sound sources)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Demolition....... 1 35.6-cm (14-in) Removal--vibratory. Nonimpulsive....... 160 dB RMS......... Greenbusch 2018.... 10 minutes.
timber.
61.0-cm (24-in) 160 dB RMS......... Greenbusch 2018.... 10 minutes.
timber.
30.5-cm (12-in) 155 dB RMS......... CalTrans 2015...... 10 minutes.
steel.
35.6-cm (14-in) 154 dB RMS......... CalTrans 2020...... 10 minutes.
steel.
Construction..... 61.0-cm (24-in) Installation--vibra Nonimpulsive....... 153 dB RMS......... CalTrans 2020...... 20 minutes.
steel. tory.

[[Page 26501]]

Installation--impac Impulsive.......... 190 dB RMS; 177 dB CalTrans 2015...... 1,800 strikes.
t. SELss; 203 dB peak.
Installation--DTH.. Impulsive and 167 dB RMS; 159 dB Heyvaert & Reyff 150 minutes/90,000
nonimpulsive. SELss; 184 dB peak. 2021. strikes.
76.2-cm (30-in) Installation--vibra Nonimpulsive....... 159 dB RMS......... CalTrans 2020...... 45 minutes.
vibroflot columns. tory.
91.4-cm (36-in) Temporary Nonimpulsive....... 170 dB RMS......... CalTrans 2015...... 20 minutes.
steel. installation--vibr
atory.
Temporary removal-- 170 dB RMS......... CalTrans 2015...... 20 minutes.
vibratory.
106.7-cm (42-in) Installation--vibra Nonimpulsive....... 169 dB RMS......... Reyff & Heyvaert 20 minutes.
steel. tory. 2019; NMFS 2024.
Installation--impac Impulsive.......... 192 dB RMS; 179 dB CalTrans 2020...... 2,400 strikes.
t. SELss; 213 dB peak.
61.0-cm (24-in) Removal--vibratory. Nonimpulsive....... 163 dB RMS......... NAVFAC SW \a\ 2023. 10 minutes.
steel/concrete.
61.0-cm (24-in) Installation--vibra Nonimpulsive....... 163 dB RMS......... NAVFAC SW \a\ 2023. 20 minutes.
precast concrete tory.
reaction.
61.0-cm (24-in) Installation--impac Impulsive.......... 176 dB RMS; 164 dB CalTrans 2020...... 2,400 strikes.
precast concrete t. SELss; 195 dB peak.
fender.
63.5-106.7-cm (25- Installation--DTH.. Impulsive and 174 dB RMS; 164 dB Denes et al. 2019; 150 minutes/90,000
42-in) steel. nonimpulsive. SELss; 194 dB peak. Reyff & Heyvaert strikes.
2019; Reyff 2020.
2 61.0-cm (24-in) Installation--vibra Nonimpulsive....... 153 dB RMS......... CalTrans 2020...... 20 minutes.
steel. tory.
Installation--impac Impulsive.......... 190 dB RMS; 177 dB CalTrans 2015...... 1,800 strikes.
t. SELss; 203 dB peak.
Installation--DTH.. Impulsive and 167 dB RMS; 159 dB Heyvaert & Reyff 150 minutes/90,000
nonimpulsive. SELss; 184 dB peak. 2021. strikes.
76.2-cm (30-in) Installation--vibra Nonimpulsive....... 159 dB RMS......... CalTrans 2020...... 20 minutes.
steel. tory.
Installation--impac Impulsive.......... 190 dB RMS; 177 dB CalTrans 2020...... 1,800 strikes.
t. SELss; 210 dB peak.
91.4-cm (36-in) Permanent Nonimpulsive....... 170 dB RMS......... CalTrans 2015...... 20 minutes.
steel. installation--vibr
atory.
Permanent Impulsive.......... 193 dB RMS; 183 dB CalTrans 2020...... 1,800 strikes.
installation--impa SELss; 210 dB peak.
ct.
Temporary Nonimpulsive....... 170 dB RMS......... CalTrans 2015...... 20 minutes.
installation--vibr
atory.
Temporary removal-- 170 dB RMS......... CalTrans 2015...... 20 minutes.
vibratory.
106.7-cm (42-in) Installation--vibra Nonimpulsive....... 169 dB RMS......... Reyff & Heyvaert 20 minutes.
steel. tory. 2019; NMFS 2024.
Installation--impac Impulsive.......... 192 dB RMS; 179 dB CalTrans 2020...... 2,400 strikes.
t. SELss; 213 dB peak.
63.5-106.7-cm (25- Installation--DTH.. Impulsive and 174 dB RMS; 164 dB Denes et al. 2019; 150 minutes/90,000
42-in) steel. nonimpulsive. SELss; 194 dB peak. Reyff & Heyvaert strikes.
2019; Reyff 2020.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Naval Facilities Engineering Command Southwest.

Ensonified Areas
Distances to below Level A harassment and Level B harassment
thresholds were calculated for each project activity to determine the
ensonified area for a given project activity. The USCG will implement
shutdown zones to reduce harassment of sea otters by in-water noise and
minimize the likelihood that sea otters are impacted by physical
interactions with construction equipment and materials. These shutdown
zones will encompass some of the Level A harassment and Level B
harassment zones in all three project areas.
For project activities in Seward and Sitka, a minimum 30-m (98-ft)
acoustic shutdown zone will be implemented, which will encompass most
of the Level A harassment and Level B harassment zones. During rock
socket DTH drilling, where Level A harassment zones are 75.8 m (249
ft), the applicant will implement an acoustic shutdown zone of 85 m
(279 ft), which encompasses all of the Level A harassment zone and most
of the Level B harassment zone for that activity in Seward and Sitka
(tables 9 and 10, respectively). Observers will be stationed at
multiple vantage points, some elevated, to increase detectability of
sea otters at these distances.

[[Page 26502]]

Table 9--USCG Moorings Seward: Distances to Below Level A Harassment and Level B Harassment Zones and Proposed
Acoustic Shutdown Zones *
----------------------------------------------------------------------------------------------------------------
Distance to Distance to Distance to
Pile size and below Level A below Level B below acoustic
Project component material Activity harassment harassment shutdown zones
threshold (m) threshold (m) (m)
----------------------------------------------------------------------------------------------------------------
FRC moorings................. <40.6-cm (16-in) Removal--vibrat 0.5 10.0 30.0
steel. ory.
Removal--pile 0.3 12.0 30.0
clipper.
Removal--diamon 0.4 12.6 30.0
d wire saw.
76.2-cm (30-in) Installation--r 75.8 85.8 85.0
concrete or ock socket DTH.
steel.
Installation--v 0.2 15.9 30.0
ibratory
settling.
Installation--i 0.4 541.2 30.0
mpact proofing.
New dock..................... 76.2-cm (30-in) Installation--r 75.8 85.8 85.0
concrete or ock socket DTH.
steel.
Installation--v 0.2 15.9 30.0
ibratory
settling.
Installation--i 0.4 541.2 30.0
mpact proofing.
----------------------------------------------------------------------------------------------------------------
* Work at the USCG's Moorings Seward is expected to be completed within 1 year.

Table 10--USCG Moorings Sitka: Distances to Below Level A Harassment and Level B Harassment Zones and Proposed
Acoustic Shutdown Zones *
----------------------------------------------------------------------------------------------------------------
Distance to Distance to Distance to
Pile size and below Level A below Level B below acoustic
Project component material Activity harassment harassment shutdown zones
threshold (m) threshold (m) (m)
----------------------------------------------------------------------------------------------------------------
Demolition................... 76.2-cm (30-in) Removal--vibrat 0.6 13.6 30.0
concrete. ory.
Removal--pile 0.3 12.0 30.0
clipper.
Removal--diamon 0.4 12.6 30.0
d wire saw.
35.6-cm (14-in) Removal--vibrat 0.6 10.0 30.0
timber. ory.
Construction................. 76.2-cm (30-in) Installation--r 75.8 85.8 85.0
concrete or ock socket DTH.
steel.
Installation--v 0.2 15.9 30.0
ibratory
settling.
Installation--i 0.4 541.2 30.0
mpact proofing.
35.6-cm (14-in) Installation--i 0.5 46.4 30.0
timber. mpact driving.
33.0-cm (13-in) Installation--i 0.5 3.4 30.0
composite. mpact driving.
----------------------------------------------------------------------------------------------------------------
* Work at the USCG's Moorings Sitka is expected to be completed within 1 year.

For project activities in Kodiak, the USCG will implement a minimum
20-m (66-ft) physical interaction shutdown zone, regardless of
predicted sound levels, to minimize the potential for physical impacts
to sea otters. Additionally, this 20-m (66-ft) physical interaction
shutdown zone would reduce the number of sea otters exposed to in-water
noise levels that would attenuate to Level A harassment thresholds;
however, some Level A harassment zones extend past the 20-m (66-ft)
physical interaction shutdown zone (table 11).

Table 11--USCG Base Kodiak: Distances to Below Level A Harassment and Level B Harassment Zones and Proposed Physical Interaction Shutdown Zones
--------------------------------------------------------------------------------------------------------------------------------------------------------
Distance to
Distance to below Distance to below physical
Project component Year Pile size and material Activity Level A below Level B interaction
harassment harassment shutdown zone
threshold (m) threshold (m) (m)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Demolition............................ 1 35.6-cm (14-in) timber.. Removal-vibratory....... 0.6 10.0 20.0
61.0-cm (24-in) timber.. 0.6 10.0 20.0
30.5-cm (12-in) steel... 0.3 4.6 20.0
35.6-cm (14-in) steel... 0.2 4.0 20.0
Construction.......................... 61.0-cm (24-in) steel... Installation-vibratory.. 0.1 3.4 20.0
Installation-impact..... 75.7 1,000.0 20.0
Installation-DTH........ 31.2 29.3 20.0
76.2-cm (30-in) Installation-vibratory.. 0.8 8.6 20.0
vibroflot columns.
91.4-cm (36-in) steel... Temporary installation- 1.8 46.4 20.0
vibratory.
Temporary removal- 1.8 46.4 20.0
vibratory.
106.7-cm (42-in) steel.. Installation-vibratory.. 1.6 39.8 20.0
Installation-impact..... 124.6 1,359.4 20.0
61.0-cm (24-in) steel/ Removal-vibratory....... 0.9 15.9 20.0
concrete.
61.0-cm (24-in) precast Installation-vibratory.. 0.6 15.9 20.0
concrete reaction.
61.0-cm (24-in) precast Installation-impact..... 21.8 204.0 20.0
concrete fender.
63.5-106.7-cm (25-42-in) Installation-DTH........ 67.1 85.8 20.0
steel.
2 61.0-cm (24-in) steel... Installation-vibratory.. 0.1 3.4 20.0
Installation-impact..... 75.7 1,000.0 20.0
Installation-DTH........ 31.2 29.3 20.0
76.2-cm (30-in) steel... Installation-vibratory.. 0.3 8.6 20.0
Installation-impact..... 75.7 1,000.0 20.0

[[Page 26503]]

91.4-cm (36-in) steel... Permanent installation- 1.4 46.4 20.0
vibratory.
Permanent installation- 145.1 1,584.9 20.0
impact.
Temporary installation- 1.8 46.4 20.0
vibratory.
Temporary removal- 1.8 46.4 20.0
vibratory.
106.7-cm (42-in) steel.. Installation-vibratory.. 1.6 39.8 20.0
Installation-impact..... 124.6 1,359.4 20.0
63.5-106.7-cm (25-42-in) Installation-DTH........ 67.1 85.8 20.0
steel.
--------------------------------------------------------------------------------------------------------------------------------------------------------

We subtracted the area of the respective shutdown zone from the
area ensonified to >232 dB peak or >203 dB SEL<INF>CUM</INF> re
1[micro]Pa for impulsive underwater sound and >219 dB SEL re 1[micro]Pa
for nonimpulsive (continuous) underwater sound to determine the area in
which sea otters may experience Level A harassment during the USCG's
project activities. Next, we multiplied the remaining ensonified area
for Level A harassment by the density of sea otters for each respective
project area (see Sea Otter Density) to determine the number of sea
otters that may experience Level A harassment.
To estimate the number of sea otters anticipated to experience
Level B harassment during the USCG's project activities, we subtracted
either the area of the Level A harassment zone or the area of the
shutdown zone (whichever was greater) from the area ensonified to >160
dB re 1[micro]Pa to determine the area in which sea otters may
experience Level B harassment. Next, we multiplied the remaining
ensonified area for Level B harassment by the density of sea otters for
each respective project area (see Sea Otter Density) to determine the
number of sea otters that may experience Level B harassment. For most
of the in-water noise-generating activities in Seward and Sitka, we
used the area of a circle ([pi]r\2\) to calculate the area ensonified,
where the radii (r) are the distances to below the Level B harassment
threshold (tables 9 and 10 for Seward and Sitka, respectively). The
exception is the Level B harassment zone generated by impact proofing
in Seward and Sitka; for that activity, the applicant provided
geospatial files representing the area of ensonified water clipped by
land boundaries. The number of sea otters expected to be exposed to
such sound levels during project activities in Seward and Sitka can be
found in tables 12 and 13, respectively.

[[Page 26504]]

Table 12--USCG Moorings Seward: Project Activities and Level B Harassment Events Anticipated *
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Potential
Level B Potential sea otters Total
Maximum Level B Shutdown area minus sea otters affected by potential
Project component Pile size and Activity number of Sea otter density area zone area shutdown affected by Level B Level B
material days of (km\2\) (km\2\) zone area Level B sound per harassment
activity (km\2\) sound per day events
day (rounded)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
FRC moorings............... 76.2-cm (30-in) Installation-rock 20 2.31 sea otters/km\2\ 0.02 0.02 0.00 0.00 0 0
concrete or steel. socket DTH.
Installation-impact 0.11 0.00 0.11 0.25 \a\ 2 40
proofing.
New dock................... 76.2-cm (30-in) Installation-rock 0.02 0.02 0.00 0.00 0 0
concrete or steel. socket DTH.
Installation-impact 0.11 0.00 0.11 0.25 \a\ 2 40
proofing.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
* Only activities with Level B harassment thresholds that are larger than the proposed shutdown zone are included in this table, since implementing shutdown zones larger than the Level B
harassment thresholds will prevent all take.
\a\ Potential sea otters affected by Level B sound rounded to 2 to account for mom/pup pairs.

Table 13--USCG Moorings Sitka: Project Activities and Level B Harassment Events Anticipated *
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Potential
Level B Potential sea otters Total
Maximum Level B Shutdown area minus sea otters affected by potential
Project component Pile size and Activity number of Sea otter density area zone area shutdown affected by Level B Level B
material days of (km\2\) (km\2\) zone area Level B sound per harassment
activity (km\2\) sound per day events
day (rounded)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Construction............... 76.2-cm (30-in) Installation-rock 84 0.85 sea otters/km\2\ 0.02 0.02 0.00 0.00 0 0
concrete or steel. socket DTH.
Installation-impact 0.27 0.00 0.27 0.23 \a\ 2 168
proofing.
35.6-cm (14-in) timber Installation-impact 3 0.007 0.00 0.007 0.006 \a\ 2 6
driving.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
* Only activities with Level B harassment thresholds that are larger than the proposed shutdown zone are included in this table, since implementing shutdown zones larger than the Level B
harassment thresholds will prevent all take.
\a\ Potential sea otters affected by Level B sound rounded to 2 to account for mom/pup pairs.

[[Page 26505]]

For project activities in Kodiak, the applicant provided geospatial
files representing the area of the wharf and ensonified water around
the wharf. These geospatial files were clipped by land boundaries;
therefore, only the area of ensonified water was provided by the
applicant. The number of sea otters expected to be exposed to such
noise levels that would attenuate to Level A harassment and Level B
harassment thresholds during project activities in Kodiak can be found
in tables 14 and 15, respectively.

Table 14--USCG Base Kodiak: Project Activities and Level A Harassment Events Anticipated
--------------------------------------------------------------------------------------------------------------------------------------------------------
Potential
Maximum Level A sea otters Total
Project Pile size and number of Sea otter Level A area minus affected by potential
Project component year material Activity days of density area shutdown Level A Level A
activity (km\2\) zone area sound per harassment
(km\2\) day events
--------------------------------------------------------------------------------------------------------------------------------------------------------
Demolition........... 1 35.6-cm (14-in) Removal-vibrator 10 51.81 sea 0.01 0 0 0
timber. y. otters/km\2\.
61.0-cm (24-in) 2 0.01 0 0 0
timber.
30.5-cm (12-in) 9 0.01 0 0 0
steel.
35.6-cm (14-in) 2 0.01 0 0 0
steel.
Construction......... 61.0-cm (24-in) Installation-vib 5 0.01 0 0 0
steel. ratory.
Installation-imp 5 0.08 0.05 2.82 14.12
act.
Installation-DTH 7 0.04 0.01 0.55 3.87
76.2-cm (30-in) Installation-vib 59 0.01 0 0 0
vibroflot ratory.
columns.
91.4-cm (36-in) Temporary 19 0.01 0 0 0
steel. installation-vi
bratory.
Temporary 19 0.01 0 0 0
removal-vibrato
ry.
106.7-cm (42-in) Installation-vib 32 0.01 0 0 0
steel. ratory.
Installation-imp 32 0.14 0.11 5.64 180.54
act.
61.0-cm (24-in) Removal-vibrator 1 0.01 0 0 0
steel/concrete. y.
61.0-cm (24-in) Installation-vib 7 0.01 0 0 0
precast ratory.
concrete
reaction.
61.0-cm (24-in) Installation-imp 7 0.03 <0.01 0.09 0.62
precast act.
concrete fender.
63.5-106.7-cm Installation-DTH 48 0.07 0.05 2.40 115.04
(25-42-in)
steel.
2 61.0-cm (24-in) Installation-vib 4 0.01 0 0 0
steel. ratory.
Installation-imp 4 0.08 0.05 2.82 11.30
act.
Installation-DTH 6 0.04 0.01 0.55 3.31
76.2-cm (30-in) Installation-vib 5 0.01 0 0 0
steel. ratory.
Installation-imp 5 0.08 0.05 2.82 14.12
act.
91.4-cm (36-in) Permanent 3 0.01 0 0 0
steel. installation-vi
bratory.
Permanent 3 0.16 0.13 6.94 20.83
installation-im
pact.
Temporary 9 0.01 0 0 0
installation-vi
bratory.
Temporary 9 0.01 0 0 0
removal-vibrato
ry.
106.7-cm (42-in) Installation-vib 5 0.01 0 0 0
steel. ratory.
Installation-imp 5 0.14 0.11 5.64 28.21
act.
63.5-106.7-cm Installation-DTH 17 0.07 0.05 2.40 40.74
(25-42-in)
steel.
--------------------------------------------------------------------------------------------------------------------------------------------------------

Table 15--USCG Base Kodiak: Project Activities and Level B Harassment Events Anticipated
--------------------------------------------------------------------------------------------------------------------------------------------------------
Level B Potential
area minus sea otters Total
Pile size and Maximum number Sea otter Level B Level A/ affected by potential
Project component Year material Activity of days of density area shutdown Level B Level B
activity (km\2\) zone area sound per harassment
(km\2\) day events
--------------------------------------------------------------------------------------------------------------------------------------------------------
Demolition........... 1 35.6-cm (14-in) Removal-vibrator 10 51.81 sea 0.02 0 0 0
timber. y. otters/km\2\.
61.0-cm (24-in) 2 0.02 0 0 0
timber.
30.5-cm (12-in) 9 0.01 0 0 0
steel.

[[Page 26506]]

35.6-cm (14-in) 2 0.01 0 0 0
steel.
Construction......... 61.0-cm (24-in) Installation-vib 5 0.01 0 0 0
steel. ratory.
Installation-imp 5 1.30 1.22 63.25 316.25
act.
Installation-DTH 7 0.03 0 0 0
76.2-cm (30-in) Installation-vib 59 0.02 0 0 0
vibroflot ratory.
columns.
91.4-cm (36-in) Temporary 19 0.05 0.03 1.31 24.80
steel. installation-vi
bratory.
Temporary 19 0.05 0.03 1.31 24.80
removal-vibrato
ry.
106.7-cm (42-in) Installation-vib 32 ............... 0.04 0.02 0.97 31.06
steel. ratory.
Installation-imp 32 1.59 1.45 75.17 2,405.55
act.
61.0-cm (24-in) Removal-vibrator 1 0.02 0 0 0
steel/concrete. y.
61.0-cm (24-in) Installation-vib 7 0.02 0 0 0
precast ratory.
concrete
reaction.
61.0-cm (24-in) Installation-imp 7 0.24 0.21 11.05 77.38
precast act.
concrete fender.
63.5-106.7-cm Installation-DTH 48 0.09 0.02 0.98 46.88
(25-42-in)
steel.
2 61.0-cm (24-in) Installation-vib 4 0.01 0 0 0
steel. ratory.
Installation-imp 4 1.30 1.22 63.25 253.00
act.
Installation-DTH 6 0.03 0 0 0
76.2-cm (30-in) Installation-vib 5 0.02 0 0 0
steel. ratory.
Installation-imp 5 1.30 1.22 63.25 316.25
act.
91.4-cm (36-in) Permanent 3 0.05 0.03 1.31 3.92
steel. installation-vi
bratory.
Permanent 3 1.77 1.61 83.52 250.57
installation-im
pact.
Temporary 9 0.05 0.03 1.31 11.75
installation-vi
bratory.
Temporary 9 0.05 0.03 1.31 11.75
removal-vibrato
ry.
106.7-cm (42-in) Installation-vib 5 0.04 0.02 0.97 4.85
steel. ratory.
Installation-imp 5 1.59 1.45 75.17 375.87
act.
63.5-106.7-cm Installation-DTH 17 0.09 0.02 0.98 16.60
(25-42-in)
steel.
--------------------------------------------------------------------------------------------------------------------------------------------------------

We assumed that the different types of pile-driving activities
would occur sequentially and that the total number of days of work
would equal the sum of the number of days required to complete each
type of pile-driving activity. While it is possible that on some days
more than 1 type of activity will take place, which would reduce the
number of days of exposure, we cannot know this information in advance.
As such, the estimated number of days is the maximum possible for the
planned work. Where the number of exposures expected per day was 0 to 3
or more decimal places (i.e., <0.00X), the number of exposures per day
was assumed to be 0. Where the number of exposures expected per day
would have been rounded to 1, we rounded to 2 instead to accommodate
potential mom and pup pairs of sea otters for project activities in
Seward and Sitka. For project activities in Kodiak, we rounded the
total estimated Level A harassment events and Level B harassment events
across all activities per year up to the nearest whole number.

Critical Assumptions

In order to conduct this analysis and estimate the likely number of
takes by Level A harassment and Level B harassment, several critical
assumptions were made.
Level B harassment is equated herein with behavioral responses that
indicate harassment or disturbance. There is likely a portion of
animals that respond in ways that indicate some level of disturbance
but do not experience biologically significant consequences. Our
estimates do not account for variable responses by sea otter age and
sex.
The estimates of behavioral response presented here do not account
for the individual movements of animals in response to the specified
activities. Our assessment assumes animals remain stationary (i.e.,
density does not change) for a 24-hour period, and animals do not move
out of ensonified areas in response to noise. Not enough information is
available about the movement of sea otters in response to specific
disturbances to refine this assumption.
Sound level information from pile-driving activities in a number of
locations was used to generate sound level estimates for the specified
activities (see sources in tables 6, 7, and 8). Environmental
conditions in these locations, including water depth, substrate, and
ambient sound levels may be similar to those in the project location,
but are not identical. Further,

[[Page 26507]]

estimation of ensonification areas were based on sound attenuation
models using a practical spreading loss model. These factors may lead
to actual sound values differing slightly from those estimated here.
The pile-driving activities described here will also create in-air
noise. Because sea otters spend over half of their day with their heads
above water (Esslinger et al. 2014), they will be exposed to increased
in-air noise from construction equipment. However, we have calculated
Level A harassment and Level B harassment with the assumption that a
sea otter may be harassed only 1 time per 24-hour period, and in-water
noise levels will be more disturbing and extend farther than in-air
noise. Thus, while sea otters may be disturbed by noise both in-air and
in-water, we have relied on the more conservative in-water estimates.
Although sea otters are nonmigratory, they typically move amongst
focal areas within their home ranges to rest and forage (Garshelis and
Garshelis 1984; Laidre et al. 2009). It is possible that, given the
large variability in individual home range sizes and the potential for
up to daily movement in and out of foraging or resting areas, different
individual sea otters could be found within the ensonification area
each day of the project. Thus, the FWS conservatively assumes that the
estimated harassment events may impact different sea otters for project
activities at the USCG's Moorings Seward and Moorings Sitka. We
estimate that 80 takes of 80 sea otters by Level B harassment may occur
due to the USCG's planned activities in Seward and estimate that 174
takes of 174 sea otters by Level B harassment may occur due to the
USCG's planned activities in Sitka. We used the sea otter density for
the PWS area from surveys and analyses conducted by Weitzman and
Esslinger (2015) to estimate the presence of sea otters at Seward. For
Sitka, sea otter density was calculated using a state-space model
created by Tinker et al. (2019) and a Bayesian hierarchical model
created by Eisaguirre et al. (2021). Methods and assumptions for these
surveys can be found in the original publications.
For project activities in Kodiak, we used sea otter observation
data collected during the Kodiak Ferry Terminal project to estimate the
average number of sea otters expected to be present in the Kodiak
project area. These data were collected by ABR, Inc., and methods and
assumptions for this dataset can be found in the original report (ABR
2016). We assumed that sea otter distribution and behavior observed
during the dock improvement project at the Kodiak Ferry Terminal would
be similar to sea otter distribution and behavior in the Kodiak project
area. The Kodiak Ferry Terminal project activities included impact pile
driving, vibratory pile driving, and DTH drilling, which are similar to
the project activities in Kodiak. Both project areas are located in
developed areas where sea otters are exposed to human activities. Also,
sea otters in both project areas may experience similar environmental
conditions considering the project areas are approximately 8 km (5 mi)
from each other and protected by land. We calculated a maximum daily
sea otter count of 423 sea otters during the Kodiak Ferry Terminal dock
improvement project. Therefore, we estimated that a maximum of 423 sea
otters may be exposed to in-water noise during the USCG's project
activities in Kodiak. To obtain the average number of sea otters
expected to be present in the Kodiak project area, we divided the daily
sea otter counts by the respective total area of observation for the
station at which sea otters were observed. The total area of
observation for each station is represented as the minimum convex
polygon around the spatial extent of all sea otter locations observed
at that station. The actual observed area for each station is likely
larger than the minimum convex polygon around the observed sea otter
locations, which would result in the estimated sea otter density being
biased higher than the actual sea otter density. However, this
conservative assumption avoids underestimating potential disturbance to
sea otters during project activities.

Sum of Harassment From All Sources

The USCG will conduct pile driving and marine construction
activities in Seward, Sitka, and Kodiak within the 5-year ITR period. A
summary of total numbers of estimated takes by Level A harassment and
Level B harassment by project location, year, and 5-year duration of
the proposed ITR is provided in table 16.

Table 16--Proposed ITR: Sea Otters Expected To Be Harassed; Level A Harassment and Level B Harassment Events
--------------------------------------------------------------------------------------------------------------------------------------------------------
Number of sea Number of Total number Number of sea Number of Total number
otters exposed Level A of Level A otters exposed Level B of Level B
Location to Level A harassment harassment to Level B harassment harassment
harassment events events (5 harassment events (single events (5
(single year) (single year) years) (single year) year) years)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Seward (Southcentral AK stock).......................... 0 0 0 80 80 80 *
Sitka (Southeast AK stock).............................. 0 0 0 174 174 174 *
Kodiak (Southwest AK stock)............................. 423 433 433 423 4,172 4,172
--------------------------------------------------------------------------------------------------------------------------------------------------------
* Work at the USCG's Moorings Seward and Moorings Sitka is expected to be completed within 1 year.

In a single year, we estimate up to 80 instances of take by Level B
harassment of 80 northern sea otters from the Southcentral Alaska stock
due to behavioral responses and/or TTS associated with noise exposure
during project activities in Seward. In a single year, we estimate up
to 174 instances of take by Level B harassment of 174 northern sea
otters from the Southeast Alaska stock due to behavioral responses and/
or TTS associated with noise exposure during project activities in
Sitka. Although multiple instances of Level B harassment of individual
sea otters are possible, these events are unlikely to have significant
consequences for the health, reproduction, or survival of affected
animals. The potential effects of multiple Level B harassment noise
exposures may include short-term behavioral reactions, displacement of
sea otters near active operations, and potential temporary shifts in
hearing thresholds. Considering the specified activities would occur
during a limited amount of time over non-consecutive days and in a
localized area, we do not anticipate that the effects of multiple Level
B harassment noise exposures would rise to the level of an injury or
Level A harassment. Take by Level A harassment of sea otters is not
anticipated, nor was it requested by the applicant, for project
activities in

[[Page 26508]]

Seward and Sitka. While the project activities in Seward and Sitka will
create sound levels above Level A harassment thresholds, the use of
acoustic shutdown zones of 85 m (279 ft) for DTH drilling and 30 m (98
ft) for all other activities are expected to preclude Level A
harassment events from occurring during these specified activities. The
PSOs will be stationed at multiple vantage points, some elevated, to
increase the distances at which sea otters can be reliably detected.
In a single year, we estimate up to 433 instances of take by Level
A harassment of 423 northern sea otters from the Southwest Alaska stock
due to PTS associated with noise exposure during project activities in
Kodiak. The use of soft-start procedures, zone clearance prior to
activity startup, and shutdown zones is likely to decrease both the
number of sea otters exposed to noise above Level A harassment
thresholds and the exposure time of any sea otters entering the Level A
harassment zone. This reduces the likelihood of losses of hearing
sensitivity that might impact the health, reproduction, or survival of
affected sea otters. Despite the implementation of mitigation measures,
it is anticipated that some sea otters will experience Level A
harassment via exposure to in-water noise above threshold criteria
during impact and DTH pile-driving activities. Due to sea otters' small
body size and low profile in the water, we anticipate that sea otters
will at times avoid detection before entering Level A harassment zones
for those activities. We anticipate that PSOs at Kodiak will be able to
reliably detect and prevent take by Level A harassment of sea otters by
monitoring the physical interaction shutdown zone (20 m [66 ft]);
conversely, we anticipate that at distances greater than the physical
interaction shutdown zone, sea otters will at times avoid detection.
In a single year, we estimate up to 4,172 instances of take by
Level B harassment of 423 northern sea otters from the Southwest Alaska
stock due to behavioral responses and/or TTS associated with noise
exposure during project activities in Kodiak. Although multiple
instances of Level B harassment of individual sea otters are possible,
these events are unlikely to have significant consequences for the
health, reproduction, or survival of affected sea otters. The potential
effects of multiple Level B harassment noise exposures may include
short-term behavioral reactions, displacement of sea otters near active
operations, and potential temporary shifts in hearing thresholds.
Considering the specified activities would occur during a limited
amount of time over non-consecutive days and in a localized area, we do
not anticipate that the effects of multiple Level B harassment noise
exposures would rise to the level of an injury or Level A harassment.

Determinations and Findings

Sea otters exposed to noise from the specified activities are
likely to respond with temporary behavioral modification or
displacement. The specified activities could temporarily interrupt the
feeding, resting, and movement of sea otters. The activities will occur
during a limited amount of time and in a localized area, and the
impacts associated with the project are likewise temporary and
localized. The anticipated effects are short-term behavioral reactions,
displacement of sea otters near active operations, and potential
temporary and permanent shifts in hearing thresholds.
Sea otters that encounter the specified activities may exert more
energy than they would otherwise due to temporary cessation of feeding,
increased vigilance (e.g., repeatedly spyhopping), and retreating from
the project area. We expect that affected sea otters will tolerate this
exertion without measurable effects on health or reproduction. Most of
the anticipated takes will be due to short-term Level B harassment in
the form of TTS, startling reactions, or temporary displacement. While
mitigation measures incorporated into the USCG's requests will reduce
occurrences of Level A harassment to the extent practicable, a small
number of takes by Level A harassment would be authorized for impact
pile driving and DTH drilling activities in Kodiak, which have Level A
harassment zone radii ranging in size from 21.8 to 145.1 m (71.5 to
476.0 ft).
With the adoption of the acoustic shutdown zones and physical
interaction shutdown zones incorporated in the USCG's requests and
required by this proposed ITR, anticipated take was reduced in our take
estimate analysis. Those mitigation measures are further described
below. We prescribe additional mitigation measures that would further
limit the potential impacts of the USCG's activities on sea otters.

Small Numbers

For our small numbers determination, we consider whether the
estimated number of sea otters to be subjected to incidental take is
small relative to the population size of the species or stock. More
specifically, the FWS compares the number of sea otters anticipated to
be taken in each year contemplated by the proposed ITR with the
population estimate applicable to each of those years. Here, predicted
numbers of sea otters to be taken were determined based on the
estimated density of sea otters in the project area and ensonification
areas developed using empirical evidence from similar geographic areas.
We estimate that the USCG's projects may annually result in the
incidental take of approximately:
<bullet> No more than 80 Southcentral Alaska stock northern sea
otters by Level B harassment annually and over the duration of this
proposed ITR (see Sum of Harassment from All Sources). Annual take of
80 sea otters is 0.37 percent of the best available estimate of the
current annual Southcentral Alaska stock size of 21,617 animals
(Esslinger et al. 2021; 88 FR 53510, August 8, 2023) ((80/
21,617)x100[ap]0.37) and represents a ``small number'' of sea otters of
that stock.
<bullet> No more than 174 Southeast Alaska stock northern sea
otters by Level B harassment annually and over the duration of this
proposed ITR (see Sum of Harassment from All Sources). Annual take of
174 sea otters is 0.78 percent of the best available estimate of the
current annual Southeast Alaska stock size of 22,359 animals (88 FR
53510, August 8, 2023) ((174/22,359)x100[ap]0.78) and represents a
``small number'' of sea otters of that stock.
<bullet> No more than 423 Southwest Alaska stock northern sea
otters by Level A harassment and Level B harassment annually and over
the duration of this proposed ITR (see Sum of Take from All Sources).
Annual take of 423 sea otters is 0.81 percent of the best available
estimate of the current annual Southwest Alaska stock size of 51,935
animals (88 FR 53510, August 8, 2023) ((423/51,935)x100[ap]0.81) and
represents a ``small number'' of sea otters of that stock.
Within the specified geographic region, the area of specified
activity is expected to be small relative to the range of sea otters.
Sea otters range well beyond the boundaries of the specified geographic
region. As such, the specified geographic region itself represents only
a subset of the potential area in which this species may occur, and we
anticipate that only a small proportion of sea otters would be present
within the vicinity of the specified activities.
Therefore, we propose a finding that the USCG's specified
activities will take only small numbers of sea otters because: (1) Only
a small proportion of sea otters will overlap with the areas where the
specified activities will occur;

[[Page 26509]]

(2) the estimated number of Southcentral Alaska stock northern sea
otters to be taken will be limited to a total of 80 Southcentral Alaska
stock northern sea otters annually and over the duration of the
proposed ITR; (3) the estimated number of Southeast Alaska stock
northern sea otters to be taken will be limited to a total of 174
Southeast Alaska stock northern sea otters annually and over the
duration of the proposed ITR; and (4) the estimated number of Southwest
Alaska stock northern sea otters to be taken will be limited to a total
of 423 Southwest Alaska stock northern sea otters annually and over the
duration of the proposed ITR, which represents a small proportion of
each stock of sea otters.

Negligible Impact

For our negligible impact determination, we consider the following:
1. The documented impacts of previous activities similar to the
specified activities on sea otters, taking into consideration
cumulative effects, suggests that the types of activities analyzed for
this proposed ITR will have minimal effects limited to short-term,
temporary behavioral changes, displacement of sea otters near active
operations, and potential hearing threshold shifts. This is true not
only for Level B harassment, but also Level A harassment. While Level A
harassment has the potential to result in the injury of up to 423 sea
otters at Kodiak during the ITR period, this type of harassment is not
anticipated to result in long-term impacts that are likely to result in
mortality. Most sea otters will respond to disturbance by moving away
from the sound source, which may cause temporary interruption of
foraging, resting, or other natural behaviors. Affected sea otters are
expected to resume normal behaviors soon after exposure with no lasting
consequences to their survival or reproduction. Sea otters may move in
and out of the project area during pile-driving activities, leading to
as many as 80 individuals in Seward, 174 individuals in Sitka, and 423
individuals in Kodiak experiencing exposure to noise at levels that may
cause harassment. However, it is possible that an individual may enter
the ensonification area more than once during the project. At most, if
the same sea otter enters the ensonification area every day that pile
driving occurs, the sea otter would be exposed to pile driving and
marine construction noise for up to 22 non-consecutive days in Seward,
117 non-consecutive days in Sitka, and up to 339 non-consecutive days
in Kodiak.
We do not anticipate that sea otters in Seward and Sitka will be
exposed to noise levels equal to or greater than Level A harassment
thresholds due to the applicant's implementation of acoustic shutdown
zones larger than the Level A harassment zone. It is possible that sea
otters in Kodiak may be exposed to noise levels equal to or greater
than Level A harassment thresholds on multiple days throughout project
activities. The potential effects of multiple Level A harassment noise
exposures may include a greater reduction in a sea otter's hearing
sensitivity if the sea otter is exposed to different sound levels that
can cause PTS, but this reduction in hearing sensitivity does not
equate to total hearing loss. The reduction in sea otter hearing
sensitivity caused by PTS would align with the energy produced by pile-
driving activities (e.g., low-frequency less than 2 kHz), which would
not impair the majority of a sea otter's hearing range. Sea otters do
not rely on sound to orient themselves, locate prey, or communicate
under water. Therefore, we do not anticipate impacts to sea otters'
ability to move, forage, or communicate as a result of PTS from
multiple Level A harassment noise exposures. Sea otters, especially
mothers and pups, do use sound for communication in air (McShane et al.
1995), and sea otters may monitor underwater sound to avoid predators
(Davis et al. 1987). However, we anticipate that a sea otter will
retain the majority of its hearing range if it experiences PTS from
multiple Level A harassment noise exposures and that impacts from PTS
will not have long-term consequences to a sea otter's survival and
reproduction.
It is possible that sea otters will move away from Level A
harassment zones to avoid experiencing PTS. The area that will
experience noise levels equal to or greater than Level A harassment
thresholds due to pile driving is small (approximately 0.13 km\2\), and
a sea otter that may be disturbed could escape the noise by moving to
nearby quiet areas. Further, sea otters spend over half of their time
above the surface during the summer months (Esslinger et al. 2014), and
likely no more than 70 percent of their time foraging during winter
months (Gelatt et al. 2002); thus, their ears will not be exposed to
continuous noise, thereby reducing their likelihood to experience PTS.
Some sea otters may exhibit some of the stronger responses typical of
Level B harassment, such as fleeing, interruption of feeding, or
flushing from a haulout. These responses could have temporary
biological impacts for affected individuals but are not anticipated to
result in measurable changes in survival or reproduction. Therefore, we
anticipate the specified activities will not have lasting impacts that
could significantly affect an individual's health, reproduction, or
survival. The limited extent of anticipated impacts on sea otters is
unlikely to adversely affect annual rates of sea otter survival or
recruitment.
2. The proposed ITR, if finalized, would require implementation of
monitoring requirements and mitigation measures that would limit the
potential impacts of the USCG's operations on sea otters. Adaptive
mitigation and management responses based on real-time monitoring of
the project areas by PSOs (described in this proposed authorization)
would be used to avoid or minimize interactions with sea otters and,
therefore, limit potential disturbance of these animals.
3. The FWS does not anticipate any lethal take or long-term impacts
that would remove individual sea otters from the population or prevent
their successful reproduction. Incidental harassment events are
anticipated to be limited to human interactions that lead to short-term
behavioral disturbances, displacement of sea otters near active project
operations, and potential temporary and permanent hearing threshold
shifts. These disturbances would not affect the rates of recruitment or
survival for the Southcentral Alaska, Southeast Alaska, and Southwest
Alaska stocks of sea otters. This proposed ITR does not authorize take
that will likely lead to mortality or lethal take.
We also consider the conjectural or speculative impacts associated
with these specified activities. The specific congressional direction
described below justifies balancing the probability of such impacts
with their severity.
If potential effects of a specified activity are conjectural or
speculative, a finding of negligible impact may be appropriate. A
finding of negligible impact may also be appropriate if the probability
of occurrence is low but the potential effects may be significant. In
this case, the probability of occurrence of impacts must be balanced
with the potential severity of harm to the species or stock when
determining negligible impact. In applying this balancing test, the FWS
will thoroughly evaluate the risks involved and the potential impacts
on marine mammal populations. Such determination will be made based on
the best available scientific information (53 FR 8474, March 15, 1988;
132 Cong. Rec. S 16304-5 (October. 15, 1986)).

[[Page 26510]]

The potential effects of most concern here are the potential injury
or PTS of sea otters in Kodiak resulting from exposure to noise levels
equal to or greater than Level A harassment thresholds. The FWS does
not anticipate lethal take of sea otters as a result of the USCG's in-
water activities. As a result of our analyses presented in the proposed
ITR, we estimate up to 433 takes by Level A harassment may occur
annually and up to a total of 433 takes by Level A harassment may occur
during project activities in Kodiak. While the FWS found that in-water
noise will rise to a level that may cause PTS in the areas immediately
adjacent to pile-driving activities, these noise levels will not extend
farther than 145.1 m (476.0 ft) from the sound source.
The applicant will implement PSO-monitored physical interaction
shutdown zones that will encompass the majority of the ensonified areas
in which Level A harassment may occur in Kodiak, thus minimizing
injurious take. Additionally, the use of soft-start procedures and zone
clearance prior to activity startup is likely to decrease both the
number of sea otters exposed to noise levels above Level A harassment
thresholds and the exposure time of any sea otters entering the Level A
harassment zone. These mitigation measures reduce the likelihood of
losses of hearing sensitivity that might impact the health,
reproduction, or survival of affected sea otters. A small number of
takes by Level A harassment would be authorized for impact pile driving
and DTH drilling activities that have Level A harassment zone radii
ranging in size from 21.8 to 145.1 m (71.5 to 476.0 ft), but mitigation
measures would be implemented to minimize take by Level A harassment to
the extent possible.
Despite the implementation of mitigation measures, it is
anticipated that some sea otters in Kodiak will experience Level A
harassment via exposure to in-water noise above threshold criteria
during impact pile driving and DTH drilling activities. Due to sea
otters' small body size and low profile in the water, as well as the
size of the Level A harassment zones associated with these activities,
we anticipate that sea otters will at times not be detected prior to
entering Level A harassment zones for those activities. We anticipate
that PSOs at Kodiak will be able to reliably detect and prevent take by
Level A harassment of sea otters up to the physical interaction
shutdown zone (20 m [66 ft]); conversely, we anticipate that at
distances greater than the physical interaction shutdown zone, sea
otters will at times be undetectable. If any sea otters exposed to
noise levels above Level A harassment threshold criteria do experience
PTS in the sensitivity of their hearing, it does not equate to total
hearing loss. We do not anticipate that a reduction in hearing
sensitivity would significantly affect a sea otter's health,
reproduction, or survival or otherwise cause any population-level
effects. Therefore, the FWS does not anticipate that the conjectural or
speculative impacts associated with these specified activities warrant
a finding of non-negligible impact or otherwise preclude issuance of
this proposed ITR.
We reviewed the effects of the specified pile driving and marine
construction activities on sea otters, including impacts from pile
clipping, use of a wire saw, and vibratory pile driving, impact pile
driving, and DTH drilling. Based on our review of these potential
impacts, past monitoring reports, and the biology and natural history
of sea otters, we anticipate that such effects will be limited to
short-term behavioral disturbances, displacement of sea otters near
active project operations, and potential temporary and permanent
hearing threshold shifts.
We have evaluated the potential effects of climate change on sea
otters as part of the environmental baseline. Climate change is a
global phenomenon and was considered as a potential factor that could
alter sea otter habitat and behavior. As we gain a better understanding
of climate change effects, we will incorporate the information in
future authorizations.
We preliminarily find that the impacts of these specified
activities cannot be reasonably expected to, and are not reasonably
likely to, adversely affect Southcentral Alaska, Southeast Alaska, or
Southwest Alaska stocks of sea otters through effects on annual rates
of recruitment or survival. We therefore propose a finding that the
total of the taking estimated above and authorized pursuant to a final
ITR will have a negligible impact on Southcentral Alaska, Southeast
Alaska, and Southwest Alaska stocks of sea otters. The FWS does not
propose to authorize take that will likely lead to mortality or lethal
take of sea otters, and we do not anticipate that any such take will
occur.

Least Practicable Adverse Impacts

We evaluated the practicability and effectiveness of mitigation
measures based on the nature, scope, and timing of the specified
activities; the best available scientific information; and monitoring
data from similar pile driving and marine construction activities.
After reviewing the original Requests (submitted January 19, 2024, for
Seward and Sitka and March 5, 2024, for Kodiak), the FWS discussed
additional mitigation measures with the USCG to reduce the potential
impacts of the specified activities. These additional mitigation
measures included adding more information to the USCG's descriptions of
underwater pile cutting operations, vessel activities, and in-water
sound levels associated with project support operations (e.g., use of
noise-producing hand tools and heavy equipment), deploying noise-
dampening materials (e.g., pile caps or cushions) between the pile and
hammer during pile-driving activities, and revising sea otter
monitoring and shutdown zones. The applicant incorporated these
additional mitigation measures in their revised Requests and supporting
documentation (WSP Environment and Infrastructure 2024 Request; Weston
Solutions 2024 Request). We propose a finding that the mitigation
measures included within the Requests will ensure the least practicable
adverse impacts on sea otters.
In evaluating what mitigation measures are appropriate to ensure
the least practicable adverse impact on species or stocks and their
habitat, as well as subsistence uses, we considered the manner and
degree to which the successful implementation of the measures is
expected to achieve this goal. We considered the nature of the
potential adverse impact being mitigated (likelihood, scope, range),
the likelihood that the measures will be effective if implemented, and
the likelihood of effective implementation. We also considered the
practicability of the measures for applicant implementation (e.g.,
cost, impact on operations).
To reduce the potential for disturbance from acoustic stimuli
associated with the activities, the applicant has proposed mitigation
measures, including the following:
<bullet> Using pile caps made of high-density polyethylene or
ultra-high-molecular-weight polyethylene softening materials during
impact pile driving;
<bullet> Conducting activities that may produce in-water noise
during lower tidal conditions as possible to reduce transmission of
sound into the water column;
<bullet> Using silt curtains or other containment methods to reduce
sedimentation and turbidity when conducting DTH drilling and vibroflot
column installation;
<bullet> Development of marine mammal monitoring and mitigation
plans;

[[Page 26511]]

<bullet> Visual mitigation monitoring by designated PSOs;
<bullet> Halting or delaying activity during environmental
conditions that may hinder sea otter detection, such as darkness,
adverse weather conditions, high sea states, and other times of limited
visibility;
<bullet> Maintaining the maximum distance practicable between a
vessel and raft of sea otters;
<bullet> Operating vessels in such a way as to avoid approaching
sea otters or impeding sea otter movements when traveling near the
shoreline in shallow water (<20 m [66 ft]) whenever practicable;
<bullet> Establishment of shutdown and monitoring zones;
<bullet> Site clearance before activity startup;
<bullet> Soft-start procedures; and
<bullet> Shutdown procedures.
A number of additional potential mitigation measures were
considered but determined to be not practicable. These measures are
listed below:
<bullet> Require use of bubble curtains--At the time of publication
of this proposed ITR, the applicant indicated that they were unable to
find a contractor with access to bubble curtain equipment for project
activities in Seward and Sitka. The applicant indicated that bubble
curtains would likely increase turbidity in the Kodiak project area,
which may impact water quality and marine life including sea otter prey
species. The FWS determined the required use of bubble curtains was not
practicable because bubble curtains are impossible to undertake for
project activities in Seward and Sitka and bubble curtains would not be
effective in reducing the impacts to sea otters during project
activities in Kodiak.
<bullet> Require use of other noise-dampening methods--The FWS
determined the required use of other noise-dampening methods, such as
cofferdams, pile-surrounding casings, sound mitigation screens, and
nets around piles, was not practicable because these methods were
impossible to undertake considering the number of piles being removed
or installed and the close proximity of piles to each other for project
activities in each of the three locations.
<bullet> Require use of alternate detection methods--The FWS
determined that the required use of alternate detection methods, such
as infrared sensors, thermal imaging, or surveys conducted by aircraft,
unmanned aircraft system (UAS), or vessel, was not practicable
considering that these alternate detection methods would not be as
effective in reducing impacts to sea otters and the applicant would
employ PSOs to monitor the project area for sea otters.
<bullet> Require 500-m minimum distance between vessels and sea
otter rafts--The FWS determined that vessels maintaining a minimum
distance of 500 m (1,640 ft) from a raft of sea otters was impossible
to undertake considering the width of the project area in Kodiak is
approximately 488 m (1,601 ft) wide or less, but the applicant agreed
to vessels maintaining the maximum distance between the vessel and
rafts of sea otters as practicable. The FWS determined that requiring
vessels to avoid traveling in nearshore shallow water (<20 m [<66 ft])
was impossible to undertake considering the project area in Kodiak is
located on the shoreline in water less than 20 m (66 ft) deep, but the
applicant agreed that vessels would avoid approaching or impeding sea
otter movements when traveling near the shoreline in shallow water (<20
m [<66 ft]) whenever practicable.

Impact on Subsistence Use

The specified project will not preclude access to harvest areas or
interfere with the availability of sea otters for harvest by Alaska
Native Peoples. Additionally, the USCG facilities are located in
developed areas and largely within areas where firearm use is
prohibited. We therefore preliminarily find that the USCG's anticipated
harassment will not have an unmitigable adverse impact on the
availability of Southcentral Alaska, Southeast Alaska, or Southwest
Alaska stocks of northern sea otters for subsistence uses by Alaska
Native Peoples during the specified timeframe. In making this
preliminary finding, we considered the timing and location of the
specified activities and the timing and location of subsistence harvest
activities in the area of the specified project.
The harvest of sea otters is important to Alaska Native Peoples in
the communities surrounding Seward, Sitka, and Kodiak. The USCG will be
required to contact subsistence communities that may be affected by the
pile driving and marine construction activities to discuss potential
conflicts caused by location, timing, and methods of the specified
activities. The USCG must make reasonable efforts to ensure that
activities do not interfere with subsistence hunting and that adverse
effects on the availability of sea otters are minimized. No concerns
have been voiced by the Alaska Native communities regarding the
specified activities limiting availability of sea otters for
subsistence uses. However, should such a concern be voiced, a POC,
which identifies measures to minimize any adverse effects, will be
implemented. The POC will ensure that the USCG will not have an
unmitigable adverse impact on the availability of the species or stock
for subsistence uses. This POC provides the procedures addressing how
the USCG will work with the affected Alaska Native communities and what
actions will be taken to avoid interference with subsistence hunting of
sea otters, as warranted.
The FWS has not received any reports and is not aware of
information that indicates that sea otters are being or will be
deterred from hunting areas or impacted in any way that diminishes
their availability for subsistence use by the expected level of pile
driving and marine construction activity. If there is evidence that
these pile driving and marine construction activities are affecting the
availability of sea otters for subsistence uses, we will reevaluate our
findings regarding permissible limits of take and the measures required
to ensure continued subsistence hunting opportunities.

Monitoring and Reporting

The purpose of monitoring requirements is to assess the effects of
specified activities on sea otters; ensure that take is consistent with
that anticipated in the small numbers, negligible impact, and
subsistence use analyses; and detect any unanticipated effects on the
species or stock. Monitoring plans document when and how sea otters are
observed, the number of sea otters, and their behavior during the
observation. This information allows the FWS to measure encounter
rates, examine trends in sea otter activity and distribution in the
project areas, and estimate the number of sea otters potentially
affected by the specified activities. The USCG is required to report
all observations of sea otters. To the extent possible, PSOs will
record group size, age, sex, behavior, duration of observation, and
closest approach to the project activity. Activities within the
specified geographic region may incorporate daily watch logs as well.
The FWS will provide the USCG with the most recent and up-to-date
Sea Otter Observation Form in which to record observations of sea
otters. Observations must be reported to the FWS's Marine Mammals
Management Office within 48 hours of the observation and submitted to
<a href="/cdn-cgi/l/email-protection#7b1d0c4c2416161624091e0b14090f083b1d0c08551c140d">[email&#160;protected]</a>. Details on monitoring guidelines and reporting
requirements can be read below in the rule portion of this document in

[[Page 26512]]

proposed Sec. 18.108 Monitoring and Sec. 18.109 Reporting
requirements.

Request for Public Comments

If you wish to comment on these proposed regulations or the
associated draft environmental assessment, you may submit your comments
by any of the methods described in ADDRESSES. Please identify if you
are commenting on the proposed regulations, the draft environmental
assessment, or both, make your comments as specific as possible,
confine them to issues pertinent to the proposed regulations, and
explain the reason for any changes you recommend. Where possible, your
comments should reference the specific section or paragraph that you
are addressing. The FWS will consider all comments that are received by
the close of the comment period (see DATES).

Required Determinations

Clarity of the Proposed Rule

We are required by Executive Orders (E.O.s) 12866 and 12988 and by
the Presidential memorandum of June 1, 1998, to write all rules in
plain language. This means that each rule we publish must:
(1) Be logically organized;
(2) Use the active voice to address readers directly;
(3) Use clear language rather than jargon;
(4) Be divided into short sections and sentences; and
(5) Use lists and tables wherever possible.
If you feel that we have not met these requirements, send us
comments by one of the methods listed in ADDRESSES. To better help us
revise the rule, your comments should be as specific as possible. For
example, you should tell us the numbers of the sections or paragraphs
that are unclearly written, which sections or sentences are too long,
the sections where you feel lists or tables would be useful, etc.

National Environmental Policy Act (42 U.S.C. 4321 et seq.)

We have prepared a draft environmental assessment in accordance
with the criteria of the National Environmental Policy Act (NEPA; 42
U.S.C. 4321 et seq.), the Department of the Interior regulations on
Implementation of the National Environmental Policy Act (43 CFR 46.10-
46.450), and the Department of the Interior Manual (516 DM 8). We have
preliminarily concluded that the proposed action of issuing a final ITR
would not significantly affect the quality of the human environment,
and, thus, preparation of an environmental impact statement for this
incidental take regulation, if finalized, is not required by section
102(2) of NEPA or its implementing regulations. We are accepting
comments on the draft environmental assessment as specified above in
DATES and ADDRESSES.

Endangered Species Act of 1973 (16 U.S.C. 1531 et seq.)

Under the Endangered Species Act of 1973, as amended (Act; 16
U.S.C. 1531 et seq.), all Federal agencies are required to ensure the
actions they authorize are not likely to jeopardize the continued
existence of any threatened or endangered species or result in
destruction or adverse modification of critical habitat. Prior to
issuance of a final ITR, if warranted, the FWS will complete intra-
service consultation under section 7 of the ESA. These evaluations and
findings would be made available on the FWS's website at <a href="https://ecos.fws.gov/ecp/report/biological-opinion">https://ecos.fws.gov/ecp/report/biological-opinion</a>.

Government-to-Government Consultation

It is our responsibility to communicate and work directly on a
Government-to-Government basis with federally recognized Alaska Native
Tribes and organizations in developing programs for healthy ecosystems.
We seek their full and meaningful participation in evaluating and
addressing conservation concerns for protected species. It is our goal
to remain sensitive to Alaska Native culture, and to make information
available to Alaska Natives. Our efforts are guided by the following
policies and directives:
(1) The Native American Policy of the Service (January 20, 2016);
(2) The Alaska Native Relations Policy (currently in draft form);
(3) Executive

[…truncated; see source link]

View on FederalRegister.gov →Plain-text source

Indexed from Federal Register on June 23, 2025.

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