Notice2025-18348
Marine Mammals; Incidental Take During Specified Activities; Proposed Incidental Harassment Authorization for Southcentral Alaska Stock of Northern Sea Otters at the Cruise Ship Passenger Dock and Terminal Facility in Seward, AK; Draft Environmental Assessment
Primary source
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Published
September 23, 2025
Issuing agencies
Interior DepartmentFish and Wildlife Service
Abstract
We, the U.S. Fish and Wildlife Service (FWS), in response to a request under the Marine Mammal Protection Act of 1972, as amended, from Turnagain Marine Construction (applicant), propose to authorize nonlethal, incidental take by harassment of small numbers of Southcentral Alaska stock northern sea otters (Enhydra lutris kenyoni) for a period of up to 1 year from the date of issuance. The applicant has requested this authorization for take by harassment that may result from activities associated with pile-driving and marine construction activities on the northern shore of Resurrection Bay in Seward, Alaska. We estimate that this project may result in, and propose to authorize, the nonlethal incidental take by harassment of up to 347 individual northern sea otters from the Southcentral Alaska stock. Neither the applicant nor the FWS anticipate any lethal take, and the FWS does not propose to authorize any lethal take. We invite comments on the proposed incidental harassment authorization and the accompanying draft environmental assessment from the public, and local, State, Tribal, and Federal agencies.
Full Text
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<title>Federal Register, Volume 90 Issue 182 (Tuesday, September 23, 2025)</title>
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[Federal Register Volume 90, Number 182 (Tuesday, September 23, 2025)]
[Notices]
[Pages 45791-45805]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2025-18348]
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DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
[Docket No. FWS-R7-ES-2025-0056; FXES111607MRG01-256-FF07CAMM00]
Marine Mammals; Incidental Take During Specified Activities;
Proposed Incidental Harassment Authorization for Southcentral Alaska
Stock of Northern Sea Otters at the Cruise Ship Passenger Dock and
Terminal Facility in Seward, AK; Draft Environmental Assessment
AGENCY: Fish and Wildlife Service, Interior.
ACTION: Notice of receipt of application; proposed incidental
harassment authorization; notice of availability of draft environmental
assessment; request for comments.
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SUMMARY: We, the U.S. Fish and Wildlife Service (FWS), in response to a
request under the Marine Mammal Protection Act of 1972, as amended,
from Turnagain Marine Construction (applicant), propose to authorize
nonlethal, incidental take by harassment of small numbers of
Southcentral Alaska stock northern sea otters (Enhydra lutris kenyoni)
for a period of up to 1 year from the date of issuance. The applicant
has requested this authorization for take by harassment that may result
from activities associated with pile-driving and marine construction
activities on the northern shore of Resurrection Bay in Seward, Alaska.
We estimate that this project may result in, and propose to authorize,
the nonlethal incidental take
[[Page 45792]]
by harassment of up to 347 individual northern sea otters from the
Southcentral Alaska stock. Neither the applicant nor the FWS anticipate
any lethal take, and the FWS does not propose to authorize any lethal
take. We invite comments on the proposed incidental harassment
authorization and the accompanying draft environmental assessment from
the public, and local, State, Tribal, and Federal agencies.
DATES: Comments must be received by October 23, 2025.
ADDRESSES:
Document availability: You may view the application package,
supporting information, the draft environmental assessment, and the
list of references cited herein at <a href="https://www.regulations.gov">https://www.regulations.gov</a> under
Docket No. FWS-R7-ES-2025-0056, or you may request these documents from
the person listed under FOR FURTHER INFORMATION CONTACT.
Comment submission: You may submit comments on the proposed
authorization by one of the following methods:
<bullet> Electronic Submission: Visit <a href="https://www.regulations.gov">https://www.regulations.gov</a>.
In the Search box, enterFWS-R7-ES-2025-0056, which is the docket number
for this notice. You may submit a comment by clicking on ``Comment.''
Comments must be submitted to <a href="https://www.regulations.gov">https://www.regulations.gov</a> before 11:59
p.m. eastern time/7:59 p.m. Alaska time on the date specified in DATES.
<bullet> U.S. mail: Public Comments Processing, Attn: Docket No.
FWS-R7-ES-2025-0056, U.S. Fish and Wildlife Service, MS: PRB (JAO/3W),
5275 Leesburg Pike, Falls Church, VA 22041-3803.
We request that you send comments only by the methods described
above. 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.
FOR FURTHER INFORMATION CONTACT: Dr. Stephanie Burgess, by email at
<a href="/cdn-cgi/l/email-protection#cbb9fca6a6a6b9aeacbea7aabfa4b9b28badbcb8e5aca4bd"><span class="__cf_email__" data-cfemail="a6d491cbcbcbd4c3c1d3cac7d2c9d4dfe6c0d1d588c1c9d0">[email protected]</span></a>, or by telephone at 1-800-362-5148 or 1-907-
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.
SUPPLEMENTARY INFORMATION:
Background
Section 101(a)(5)(D) of the Marine Mammal Protection Act of 1972
(MMPA; 16 U.S.C. 1361 et seq.) authorizes the Secretary of the Interior
(Secretary) to allow, upon request, the incidental, but not
intentional, taking by harassment of small numbers of 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) in a
specified geographic region during a period of not more than 1 year.
The Secretary has delegated authority for implementation of the MMPA to
the U.S. Fish and Wildlife Service (FWS, or we). According to the MMPA,
the FWS shall allow this incidental taking by harassment if we make
findings that the total of such taking for the 1-year period:
1. Is of small numbers of marine mammals of a species or stock;
2. Will have a negligible impact on such species or stocks; and
3. Will not have an unmitigable adverse impact on the availability
of these species or stocks for taking for subsistence use by Alaska
Natives.
If the requisite findings are made, we issue an authorization that
sets forth the following, where applicable:
1. Permissible methods of taking;
2. 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
3. Requirements for monitoring and reporting of such taking by
harassment, including, in certain circumstances, requirements for the
independent peer review of proposed monitoring plans or other research
proposals.
The term ``take'' means to harass, hunt, capture, or kill, or to
attempt to harass, hunt, capture, or kill any marine mammal.
``Harassment'' means any act of pursuit, torment, or annoyance which
(i) has the potential to injure a marine mammal or marine mammal stock
in the wild (the MMPA defines this as ``Level A harassment''), or (ii)
has the potential to disturb a marine mammal or marine mammal stock in
the wild by causing disruption of behavioral patterns, including, but
not limited to, migration, breathing, nursing, breeding, feeding, or
sheltering (the MMPA defines this as ``Level B harassment'').
The terms ``negligible impact'' and ``unmitigable adverse impact''
are defined in 50 CFR 18.27 (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.
However, we do not rely on that definition here as it conflates ``small
numbers'' with ``negligible impact.'' We recognize ``small numbers''
and ``negligible impact'' as two separate and distinct considerations
when reviewing requests for incidental harassment authorizations (IHA)
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 takes of marine mammals
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. For this IHA, we ensure the least
practicable adverse impact by requiring mitigation measures that are
effective in reducing the impact of project activities, but they are
not so restrictive as to make project activities unduly burdensome or
impossible to undertake and complete.
If the requisite findings are made, we shall issue an IHA, which
may set forth the following, where applicable: (i) permissible methods
of taking; (ii) other means of effecting the least practicable impact
on the species or stock and its habitat, paying particular attention to
rookeries, mating grounds, and areas of similar significance, and on
the availability of the species or stock for taking for subsistence
uses by coastal-dwelling Alaska Natives (if applicable); and (iii)
requirements for monitoring and reporting take by harassment.
Summary of Request
On November 8, 2024, Turnagain Marine Construction (hereafter, TMC
or the applicant) submitted a request to the FWS for an authorization
to take by
[[Page 45793]]
Level A harassment and Level B harassment of northern sea otters
(Enhydra lutris kenyoni) (hereafter, sea otters or otters unless
another species is specified) from the Southcentral Alaska stock. The
FWS sent a request for additional information on January 7, 2025. We
received additional information on January 10, 2025, and requested
further information on January 31, 2025. We received an updated version
of the request on April 7, 2025, and determined the application to be
adequate and complete. The applicant expects take by harassment may
occur during the construction of their cruise ship berth and associated
facilities on the northern shore of Resurrection Bay in Seward, Alaska.
Description of Specified Activities and Specified Geographic Region
The specified activity (hereafter project) will include the
following: (1) removal of the existing passenger terminal building,
passenger dock, and associated steel piles, (2) dredging and offshore
disposal, and (3) installation of an ~92 by ~15 meter (m) (300 by 50
feet (ft)) pile-supported fixed dock, an ~31 m (100 ft) transition
ramp, an ~238 m (780 ft) by ~31m (100 ft) floating dock structure
supported by three float restraint dolphins, and two mooring dolphins
in Seward, Alaska. Figure 1 shows the specified geographic region of
the project. The applicant, TMC, plans to remove 1,830 existing steel
piles, 1,820 of which will be ~36 centimeters (cm) (14 inches (in)) in
diameter and 10 of which will be ~51 cm (20 in) in diameter. During the
course of work, one hundred steel piles with a diameter of ~91 cm (36
in) will be installed to support construction and subsequently removed.
The following piles will be permanently installed: 76 steel piles of
~122 cm (48 in) diameter, 16 steel piles of ~152 cm (60 in) diameter,
and 16 piles of ~183 cm (72 in) diameter. There will also be
installation of dock components out of the water, including bull rails,
fenders, mooring cleats, pre-cast concrete dock, a passenger walkway
with handrail, and mast lights. Pile-driving activities will occur over
204 non-consecutive days during the 1 year from date of issuance of the
IHA. The project may commence as soon as July, 2025, although the
project schedule may be delayed to accommodate finalization of the IHA
or for other reasons. If the IHA is issued after TMC's intended start
date, the schedule for conducting the specified activities may be
adjusted accordingly. Pile installation will be done with a combination
of impact, vibratory, and down-the-hole (DTH) drilling. Temporary and
existing piles will be removed by the dead-pull method (a direct lift
of the pile using a crane) with or with the vibratory hammer. Materials
and equipment will be transported via barges that will remain
stationary most of the course of work. Skiffs may be used for short
trips within frequently utilized navigation lanes as part of day-to-day
operations near the docks. Mitigation measures will include soft-start
procedures and hammer cushions where practicable, shutdown radii, pre-
clearance of ensonification zones, use of bubble curtains for larger
piles where bathymetry allows, and standoff distances between vessels
and sea otters.
Additional project details may be reviewed in the application
materials available as described under ADDRESSES or may also be
requested as described under FOR FURTHER INFORMATION CONTACT.
BILLING CODE 4333-15-P
[[Page 45794]]
[GRAPHIC] [TIFF OMITTED] TN23SE25.000
BILLING CODE 4333-15-C
Figure 1. Specified geographic region of the project.
Description of Marine Mammals in the Specified Geographic Region
The northern sea otter is the only marine mammal under the FWS's
jurisdiction that normally occupies the Northeast Pacific Ocean. Sea
otters in Alaska are represented by three stocks: the Southwest Alaska
stock, the Southcentral Alaska stock, and the Southeast Alaska stock.
Northern sea otters in the waters surrounding Seward belong to the
Southcentral Alaska stock. Detailed information about the biology of
the Southcentral Alaska stock can be found in the most recent stock
assessment report (88 FR 53510; August 8, 2023), available at <a href="https://www.fws.gov/project/marine-mammal-stock-assessment-reports">https://www.fws.gov/project/marine-mammal-stock-assessment-reports</a>.
Sea otters may be distributed anywhere within the specific
geographic region other than upland areas; however, they generally
occur in shallow water near the shoreline. They are most commonly
observed within the 40-m (131-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) (0.62 to 1.24 miles
(mi)) of shore (Riedman and Estes 1990). They tend to be found closer
to shore during storms, but they venture farther out during calm
weather and sea state (Lensink 1962; Kenyon 1969).
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 (298.56 ft) of altitude. The combined estimates of the three
regions resulted in approximately
[[Page 45795]]
21,617 (standard error = 2,190) sea otters and an average density of
1.96 sea otters per square kilometer (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 previous FWS stock
assessment report in 2014 (88 FR 53510, August 8, 2023). The maximum
rate of productivity 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).
The most recent localized surveys that have been conducted near the
project location are aerial surveys in PWS during the summer of 2014.
These aerial surveys were flown using 400 m wide transects and have
incorporated detection probability to best estimate sea otter
abundance, resulting in a density of 2.31 sea otters/km\2\ (Weitzman
and Esslinger 2015). Distribution of the sea otter population during
the specified project is likely similar to that detected during sea
otter surveys, as work will occur during the same time of the year that
these surveys were conducted.
The documented home range sizes and movement patterns of sea otters
illustrate the types of movements that could be seen among otters
responding to the proposed activities. Sea otters are nonmigratory and
generally do not disperse over long distances (Garshelis and Garshelis
1984). They usually remain within a few kilometers of their established
feeding grounds (Kenyon 1981). Breeding males stay for all or part of
the year in a breeding territory covering up to 1 km (0.62 mi) of
coastline, while adult females have home ranges of approximately 8 to
16 km (5 to 10 mi), which may include one or more male territories.
Juveniles move greater distances between resting and foraging areas
(Lensink 1962; Kenyon 1969; Riedman and Estes 1990; Estes and Tinker
1996). Although sea otters generally remain local to a handful of focal
areas, they are capable of long-distance travel. 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).
Additional information on range, stocks, and biology of sea otters can
be found in the supplemental information (available as described above
in ADDRESSES).
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
experiences, 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 that
falls 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). 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 101 and 116 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. Unlike other
marine mammals, sea otters do not rely on sound to orient themselves,
locate prey, or communicate under water; therefore, masking of
communications by anthropogenic sound 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 (which entails the potential for
injury) to marine mammal species, including sea otters, have been
established using the same methods as those used by the 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 hairs
within the inner ear system to die (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. The 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). The TTS is a noise-induced threshold
shift in hearing sensitivity that fully recovers over time (Finneran
2015). Southall and colleagues (2019) predict that PTS for sea otters,
which are included in the ``other marine carnivores'' category, will
occur at 232 dB peak or 203 dB SEL<INF>CUM</INF> for impulsive
underwater sound and 219 dB SEL<INF>CUM</INF> for nonimpulsive
(continuous) underwater sound.
Thresholds based on TTS have been used as a proxy for Level B
harassment (i.e., 70 FR 1871, January 11, 2005; 71 FR 3260, January 20,
2006; 73 FR 41318, July 18, 2008). Southall et al. (2007) derived TTS
thresholds for pinnipeds based on 212 dB peak and 171 dB SEL. Exposures
resulting in TTS in pinnipeds were found to range from 152 to 174 dB
(183 to 206 dB SEL) (Kastak et al. 2005), with a persistent TTS, if not
a PTS, after 60 seconds of 184 dB SEL (Kastak et al. 2008). Kastelein
et al. (2012) found small but statistically significant TTSs
[[Page 45796]]
at approximately 170 dB SEL<INF>CUM</INF> (136 dB, 60 minutes) and 178
dB SEL<INF>CUM</INF> (148 dB, 15 minutes). Based on these findings,
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. The NMFS
(2024a) has recently updated their Technical Guidance for Assessing the
Effects of Anthropogenic Sound on Marine Mammal Hearing utilizing the
work of Southall et al. (2019), but they have retained the 160-dB
threshold for Level B harassment from exposure to impulsive noise and a
120-dB threshold for continuous noise (NMFS 2024b). The FWS is
evaluating the new auditory injury criteria from NMFS to determine
whether they are appropriate for FWS trust species. Pending the outcome
of those evaluations, the FWS will continue to use the previous version
of the technical guidance (NMFS 2018) in our estimates of potential
harassment via underwater sound.
The NMFS (2018) criteria do not identify thresholds for avoidance
of Level B harassment. For pinnipeds (seals and sea lions), the NMFS
has adopted a 160-dB threshold for Level B harassment from exposure to
impulsive noise and a 120-dB threshold for continuous noise (NMFS 1998;
HESS 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 and 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 (SPL)
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). Gray whales exhibited
avoidance to industrial noise at the 120-dB threshold; however, 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
Level B take by disturbance for sea otters for this IHA. 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 sounds
between 125 Hz and 38 kHz will be 232 dB peak or 203 dB SEL for
impulsive sounds and 219 dB SEL for continuous sounds (table 1).
Table 1--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).
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 sounds, 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.
Evidence From Sea Otter Studies
Individual sea otters in Resurrection Bay 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
[[Page 45797]]
behaviors, such as feeding and nursing pups. Sea otter responses to
disturbance can result in energetic costs, which increases the amount
of prey required by sea otters (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; Tinker and Estes 1996), we expect some individuals 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.
Additional information on the evidence from studies about how sea
otters may be affected by sound can be found in the supplemental
information to this document (available as described above in
ADDRESSES).
Consequences of Disturbance
Information on the consequences of disturbance to sea otters can be
found in the supplemental information to this document (available as
described above in ADDRESSES).
Vessel Activities
Vessel activity during the project includes the transit of barges
for materials and construction, all of which will remain on site,
mostly stationary, to support the work; additionally, a skiff will be
used for short trips within the project area. Vessels will not be used
extensively during the planned work; therefore, we do not anticipate
that sea otters will experience changes in behavior indicative of
tolerance or habituation.
Additional information on vessel activities can be found in the
supplemental information to this document (available as described above
in ADDRESSES).
Effects on Sea Otter Habitat and Prey
Information on the potential impacts of the specified activities on
sea otter prey species can be found in the supplemental information to
this document (available as described above in ADDRESSES). Based on
this information, we do not anticipate any harassment to sea otters
stemming from effects to sea otter habitat or prey.
Potential Impacts of the Specified Activities on Subsistence Uses
The planned specified activities will occur in areas rarely used
for subsistence harvesting activity. No subsistence harvest of sea
otters was documented in Seward from 2013 through 2022, and only two
sea otters were harvested in 2023.
The planned project would occur within the city limits of Seward,
where firearm use is prohibited. The area potentially affected by the
planned project does not significantly 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.
Despite no conflict with subsistence use being anticipated, the FWS
will conduct outreach with potentially affected communities to gather
any questions, concerns, or potential conflicts regarding subsistence
use in those areas. If any conflicts are identified in the future, TMC
will develop a plan of cooperation specifying the steps necessary to
minimize any effects the project may have on subsistence harvest.
Estimated Take
Definitions of Incidental Take Under the Marine Mammal Protection Act
Below we provide the circumstances under which three types of take
of northern sea otters may occur. The FWS does not anticipate and is
not proposing to authorize lethal take as a part of this proposed IHA,
nor did the applicant request authorization of lethal take; however,
all take types are discussed for context and background.
Lethal Take--Human activity may result in biologically significant
impacts to northern sea otters. In the most serious interactions, human
actions can result in the mortality of sea otters.
Level A Harassment--Human activity may result in injury to sea
otters. Level A harassment for nonmilitary readiness activities is
defined as any act of pursuit, torment, or annoyance that has the
potential to injure a marine mammal or marine mammal stock in the wild.
Level B Harassment--Level B harassment for nonmilitary readiness
activities means any act of pursuit, torment, or annoyance that has the
potential to disturb a marine mammal or marine mammal stock in the wild
by causing disruption of behaviors or activities, including, but not
limited to, migration, breathing, nursing, feeding, or sheltering.
Human-caused changes in behavior that disrupt biologically significant
behaviors or activities for the affected animal indicate take by Level
B harassment under the MMPA.
The FWS has identified the following sea otter behaviors as
indicative of possible Level B harassment:
<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 so that the raft
disperses;
<bullet> Sudden diving of an entire raft; or
<bullet> Flushing animals off a haulout.
This list is not meant to encompass all possible behaviors; other
behavioral responses may also be indicative of Level B harassment.
Relatively minor changes in behavior such as increased vigilance or a
short-term change in 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 Level B harassment.
Calculating Take
The FWS does not anticipate the Level A or Level B harassment of
sea otters resulting from vessel operations, dredging, or placement of
dredged material in the waterway. Vessels will be operated in areas
with year-round boat traffic at conservatively slow speeds,
significantly reducing the probability of sea otter harassment.
Dredging and deposition of material is not anticipated to generate
appreciable underwater noise (ERDC 2001, Dickerson et al. 2001, Nedwell
and Howell 2004). Finally, otters are not anticipated to be physically
injured due to dredging or deposition due to the use of protected
species observers and shutdown zones.
We assumed all animals 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 harassment due to
exposure to underwater noise. Spatially explicit zones of
ensonification were established around the planned construction
location to estimate the number of otters that may be exposed to these
sound levels. We determined the number of
[[Page 45798]]
otters present in the ensonification zones using density information
generated by Weitzman and Esslinger (2015).
The project can be divided into three major components: DTH
drilling, vibratory drilling, and pile driving using an impact driver.
Each of these components will generate a different type of in-water
noise. Vibratory drilling and pile removal will produce nonimpulsive or
continuous noise; impact driving will produce impulsive noise; and 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 listed in table 2.
We used the empirical data from those proxy projects 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 1). For the 60-in and 72-in piles, the
applicant presented two operational scenarios: (1) the maximum number
of piles driven per day, and (2) the likely number of piles driven per
day. To calculate ensonification areas, we used the scenario with the
maximum possible piles driven per day to account for the longest
potential duration of sound production within a 24-hour period. The
weighting factor adjustment included in the NMFS user spreadsheet
accounts for sounds created in portions of an organism'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.
Table 2--Summary by Project Component of Sound Level, Reference for Sound Information, Timing of Sound Production, and Maximum Number of Piles per Day
for Installation and Removal of Piles at the Project Area in Seward, Alaska
--------------------------------------------------------------------------------------------------------------------------------------------------------
Proxy sound source level at 10m
(dB) Minutes Total Maximum number
Activity --------------------------------- Reference per pile number of of piles per
Peak SEL RMS piles day
--------------------------------------------------------------------------------------------------------------------------------------------------------
Vibratory Pile Driving or Removal
--------------------------------------------------------------------------------------------------------------------------------------------------------
14-inch H pile removal.............................. ......... ......... 160 PR1 2023 Calculations; 5 1,820 40
Anacortes, WA (Sexton
2007).
20-inch steel pile removal.......................... ......... ......... 163 Naval Base Kitsap Bangor 10 10 4
Test Pile (U.S. Navy,
2012) and EHW-2 (U.S.
Navy, 2013).
36-inch steel pile installation..................... ......... ......... 166 PR1 2023 Calculations; 10 100 6
36-inch steel pile removal.......................... ......... ......... 166 Naval Base Kitsap Bangor 10 100 6
Test Pile (U.S. Navy
(2012)) and EHW-2 (U.S.
Navy (2013)), Anacortes
(Sexton, 2007), Edmonds
Ferry Terminal (Laughlin
2011, 2017), Gustavus
(Miner, 2020).
48-inch steel pile installation..................... ......... ......... 176 (171) PR1 2023 Calculations; 10 76 6
60-inch steel pile installation..................... ......... ......... 176 (171) Naval Base Kitsap Bangor 15 16 4
72-inch steel pile installation..................... ......... ......... 176 (171) Test Pile (U.S. Navy, 20 16 4
2012) and EHW-2 (U.S.
Navy, 2013).
--------------------------------------------------------------------------------------------------------------------------------------------------------
Impact Pile Driving
--------------------------------------------------------------------------------------------------------------------------------------------------------
48-inch steel pile installation..................... 213 (208) 179 (174) 192 (187) Caltrans 2020; Alameda Bay, 120 64 4
CA.
60-inch steel pile installation..................... 210 (205) 185 (180) 195 (190) Caltrans 2020; Richmond San 120 16 3
72-inch steel pile installation..................... 210 (205) 185 (180) 195 (190) Rafael Bridge, CA. 120 16 3
--------------------------------------------------------------------------------------------------------------------------------------------------------
DTH Drilling
--------------------------------------------------------------------------------------------------------------------------------------------------------
36-inch steel pile installation..................... 174 164 ......... Denes et al. 2019; NMFS 120 24 4
2022 ``Acoustic Guidance
for Assessment of Down-the-
hole Systems'' 25'' to
42'' pile hole/diameters
(Reyff and Heyvaert 2019;
Reyff 2020).
48-inch steel pile installation..................... 178 (173) 168 (163) ......... NMFS 2024.................. 150 12 4
60-inch steel pile installation..................... 174 (169) 181 (176) ......... U.S. Navy Construction at 240 8 2
72-inch steel pile installation..................... 174 (169) 181 (176) ......... Portsmouth Naval Shipyard, 360 5 2
Kittery, Maine (NOAA 2023).
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: Sound levels for all sources are unweighted and given in dB re 1 [micro]Pa. Nonimpulsive sounds are in the form of mean maximum root mean square
(RMS) sound pressure level (SPL) as it is more conservative than cumulative sound exposure level (SEL) or peak SPL for these activities. Values in
parenthesis indicate sound level reduced by 5 dB re 1 [micro]Pa through use of a bubble curtain.
The spreadsheet also incorporates a transmission loss coefficient,
which accounts for the reduction in sound level outward from a sound
source. We used the NMFS-recommended transmission loss coefficient of
15 for coastal pile-driving activities to indicate practical spread
(NMFS 2020).
To calculate the area ensonified for each type of pile-driving
activity, the coordinates of the piles were mapped in ArcGIS Pro. We
used a representative pile of each size around which to map the Level A
harassment and Level B harassment zones. We chose representative piles
that were farthest from shore to estimate in-water areas based on
maximum watering during tidal cycles. Where radii are small enough that
their defined circles will fall entirely in the water, the area was
calculated as [pi]r\2\. For larger radii, we used ArcGIS Pro to map and
calculate the area of the water ensonified by those activities.
To determine the number of sea otters that may experience in-water
sounds capable of causing either Level A or B harassment, we multiplied
the area ensonified to the corresponding sound threshold by the density
of animals. We used a density of 2.31 sea otters per square kilometer
(km\2\) derived from surveys conducted in PWS, Alaska (Weitzman and
Esslinger 2015). The number of sea otters expected to be exposed to
such sound levels can be found in tables 3 and 4. We calculated the
harassment zones for DTH drilling with input from NMFS. The sound
pressure levels produced by DTH drilling were provided by NMFS in 2024
via correspondence with Solstice Alaska Consulting, who created the
application for this IHA on behalf of
[[Page 45799]]
TMC. We then used the NMFS Technical Guidance and User Spreadsheet
(NMFS 2018, 2020) to determine the distance at which these sounds would
attenuate to Level A harassment thresholds. To estimate the distances
at which sounds could potentially cause Level B harassment, we again
used 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 [micro]Pa. However, due to the differences in how PTS
and TTS thresholds are calculated, as well as limited data of
underwater sound pressure levels from DTH drilling, the resultant Level
A isopleths are larger than the Level B isopleths.
Table 3--Summary by Project Component of Distance From Sound Source to Below Level A Harassment Thresholds, Days of Impact, Sea Otters in Level A
Harassment Ensonification Area, and Total Number of Level A Harassment Events Expected by Pile Installation and Removal of Piles at the Project Area in
Seward, Alaska
--------------------------------------------------------------------------------------------------------------------------------------------------------
Total
Distance to Potential sea Potential sea Maximum number potential
Activity below level A Ensonified otters exposed otters exposed of days of level A
harassment area (km\2\) per day per day activity harassment
threshold (m) (calculated) (rounded) events
--------------------------------------------------------------------------------------------------------------------------------------------------------
Vibratory Pile Driving or Removal
--------------------------------------------------------------------------------------------------------------------------------------------------------
14-inch H pile removal.................................. 0.6 1.13*10e-6 2.61*10e-6 0 46 0
20-inch steel pile removal.............................. 0.3 2.83*10e-7 6.53*10e-7 0 3 0
36-inch steel pile installation......................... 0.6 1.13*10e-6 2.61*10e-6 0 17 0
36-inch steel pile removal.............................. 0.6 1.13*10e-6 2.61*10e-6 0 17 0
48-inch steel pile installation, no bubble curtain...... 1.4 6.16*10e-6 1.42*10e-5 0 11 0
48-inch steel pile installation, with bubble curtain \1\ 0.6 1.13*10e-6 2.61*10e-6 0 2 0
60-inch steel pile installation \1\..................... 0.6 1.13*10e-6 2.61*10e-6 0 16 0
72-inch steel pile installation \1\..................... 0.8 2.01*10e-6 4.64*10e-06 0 16 0
--------------------------------------------------------------------------------------------------------------------------------------------------------
Impact Pile Driving
--------------------------------------------------------------------------------------------------------------------------------------------------------
48-inch steel pile installation, no bubble curtain...... 110.4 0.03829 0.08845 2 16 32
48-inch steel pile installation, with bubble curtain \1\ 51.2 0.00824 0.01902 2 3 6
60-inch steel pile installation \1\..................... 106.2 0.03543 0.08184 2 16 32
72-inch steel pile installation \1\..................... 106.2 0.03543 0.08184 2 16 32
--------------------------------------------------------------------------------------------------------------------------------------------------------
DTH Drilling
--------------------------------------------------------------------------------------------------------------------------------------------------------
36-inch steel pile installation......................... 123.0 0.04753 0.10979 2 6 12
48-inch steel pile installation, no bubble curtain...... 240.5 0.18171 0.41975 2 5 10
48-inch steel pile installation, with bubble curtain \1\ 111.6 0.26348 0.09038 2 1 2
60-inch steel pile installation \1\..................... 579.4 1.05464 2.04417 3 8 24
72-inch steel pile installation \1\..................... 759.3 1.81124 3.12362 4 5 20
-----------------------------------------------------------------------------------------------
Total number of Level A harassment events........... .............. .............. .............. .............. .............. 170
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Indicates that sound source levels have been reduced by 5 dB re 1[micro]Pa to reflect use of a bubble curtain.
Table 4--Summary by Project Component of Distance From Sound Source to Below Level B Harassment Thresholds, Days of Impact, Sea Otters in Level B
Harassment Ensonification Area, and Total Number of Level B Harassment Events Expected by Pile Installation and Removal of Piles at the Project Area in
Seward, Alaska
--------------------------------------------------------------------------------------------------------------------------------------------------------
Potential sea Total
Distance to otters Potential sea Maximum number potential
Activity below level B Ensonified exposed per otters of days of level B
harassment area (km\2\) day exposed per activity harassment
threshold (m) (calculated) day (rounded) events
--------------------------------------------------------------------------------------------------------------------------------------------------------
Vibratory Pile Driving or Removal
--------------------------------------------------------------------------------------------------------------------------------------------------------
14-inch H pile removal.................................. 10.00 0.000314 0.00072 0 46 0
20-inch steel pile removal.............................. 15.85 0.0007 0.00182 2 3 6
36-inch steel pile installation......................... 25.12 0.00198 0.00458 2 17 34
36-inch steel pile removal.............................. 25.12 0.00198 0.00458 2 17 34
48-inch steel pile installation, no bubble curtain...... 54.12 0.00920 0.02124 2 11 22
48-inch steel pile installation, with bubble curtain \1\ 25.12 0.00198 0.00458 2 2 4
60-inch steel pile installation \1\..................... 25.12 0.00198 0.00458 2 16 32
72-inch steel pile installation \1\..................... 25.12 0.00198 0.00458 2 16 32
--------------------------------------------------------------------------------------------------------------------------------------------------------
Impact Pile Driving
--------------------------------------------------------------------------------------------------------------------------------------------------------
48-inch steel pile installation, no bubble curtain...... 1360 3.18066 7.25886 8 16 128
48-inch steel pile installation, with bubble curtain \1\ 631 1.25069 2.87007 3 3 9
60-inch steel pile installation \1\..................... 1000 2.01509 4.57301 5 16 80
72-inch steel pile installation \1\..................... 1000 2.01509 4.57301 5 16 80
--------------------------------------------------------------------------------------------------------------------------------------------------------
DTH Drilling \2\
--------------------------------------------------------------------------------------------------------------------------------------------------------
36-inch steel pile installation......................... 85.78 .............. .............. .............. .............. ..............
[[Page 45800]]
48-inch steel pile installation, no bubble curtain...... 158.5 .............. .............. .............. .............. ..............
48-inch steel pile installation, with bubble curtain \1\ 73.56 .............. .............. .............. .............. ..............
60-inch steel pile installation \1\..................... 39.81 .............. .............. .............. .............. ..............
72-inch steel pile installation \1\..................... 39.81 .............. .............. .............. .............. ..............
-----------------------------------------------------------------------------------------------
Total number of Level B harassment events........... .............. .............. .............. .............. .............. 461
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Indicates that sound source levels have been reduced by 5 dB re 1[micro]Pa to reflect use of a bubble curtain.
\2\ Radii for sound isopleths for Level B harassment are presented for reference. Level A radii exceed Level B radii and therefore no level B harassment
is expected beyond what is calculated for Level A harassment, see Table 2, above.
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 one type of activity will take place, which would reduce the
number of days of exposure within a year, we cannot know this
information in advance. As we discussed above, the applicant presented
two operational scenarios with maximum and likely number of piles
driven per day for their ~152-cm (60-in) and ~183-cm (72-in) piles.
When estimating the number of project days, we used the scenario with
the minimum possible numbers of piles driven per day to account for the
highest possible number of days on which pile driving could occur. As
such, the estimated number of days and, therefore, exposures per year
is the maximum possible for the planned work. Where the number of
exposures expected per day was zero to three or more decimal places
(i.e., <0.00X), the number of exposures per day was assumed to be zero.
To minimize exposure of sea otters to sounds above Level A
harassment thresholds, TMC will implement 10 m (~33 ft) shutdown zones,
where operations will cease should a sea otter enter or approach the
specified zone. Soft-start and zone clearance prior to startup will
also limit the exposure of sea otters to sound levels that could cause
PTS. However, the size and shape of the structure may impede the field
of vision of PSOs, and so we assumed that some otters may be exposed to
sounds capable of causing Level A harassment.
Although sea otters are non-migratory, they typically move amongst
focal areas within their home ranges to rest and forage (Garshelis and
Garshelis 1984; Laidre et al. 2009). The project area is located at the
north, and furthest inland, end of Resurrection Bay, which has a length
of just under 30 km (~18.6 mi) and an area of roughly 150 km\2\ (~58
mi\2\). It is possible that, given the large variability in individual
home range sizes and the potential for daily movement in and out of
foraging or resting areas, different individual sea otters could be
found within the ensonification zone on different work days. The width
and length of Resurrection Bay make it unlikely that there would be
100% daily turnover of individual animals at the project area.
Similarly, if sea otters from nearby coastline were to enter
Resurrection Bay to seek calmer waters during rough weather, we would
not expect those animals to travel far enough inshore to reach the
areas ensonified by pile driving and removal. To find the maximum
number of individual sea otters that might be affected by project
activities, we multiplied the area of Resurrection Bay by the expected
density of sea otters. This resulted in ~347 animals (150 km\2\
multiplied by 2.31 sea otters per km\2\ = 346.5). Thus, the FWS
conservatively assumes that the 631 estimated harassment events may
impact up to 347 different sea otters.
Critical Assumptions
We estimate that takes by Level B and Level A harassment of up to
347 sea otters may occur due to TMC's planned cruise ship dock
construction activities. To conduct this analysis and estimate the
potential amount of take by harassment, several critical assumptions
were made.
In estimating anticipated Level B harassment, we recognize that
there is likely a portion of animals that will respond in ways that
indicate some temporary and minor level of disturbance but do not
constitute a disruption of behavioral patterns.
We used the sea otter density for the Seward area from surveys and
analyses conducted by Weitzman and Esslinger et al. (2015). Methods and
assumptions for these surveys can be found in the original publication.
We used sound source verification from recent pile-driving
activities in several locations within and beyond Alaska to generate
sound level estimates for construction activities. Environmental
conditions in these locations, including water depth, substrate, and
ambient sound levels, are similar to those in the project location, but
not identical. Further, estimation of ensonification zones 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.
We assume that all piles will be installed and removed while
submerged in water. Some of the piles may be located in the intertidal
zone. Work performed at lower tidal heights would likely result in
decreased transmission of sounds to the water column. Here, the
operator will conduct work at lower tidal heights to the maximum extent
practicable. However, as the timing of pile installation and removal
was not known in advance, we accounted for the possibility that all
work may occur at a tidal height that allows for full sound
transmission. This ensures that our estimate of the number of sea
otters potentially exposed to sound reflects the most impactful
operational scenarios.
Finally, the pile-driving activities described here will also
create in-air noise. Because sea otters spend on average over half of
their day with their heads above water (Esslinger et al. 2014), they
will be exposed to an increase in-air noise from construction
[[Page 45801]]
equipment. However, we have calculated Level B harassment with the
assumption that an individual may be harassed only one time per 24-hour
period, and underwater sound 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 underwater, we have relied on the more
conservative underwater estimates.
Sum of Harassment From All Sources
The applicant plans to conduct pile-driving and marine construction
activities in Seward Alaska, over the course of a year from the date of
issuance of the IHA. Over the course of the project, we estimate 461
instances of take by Level B harassment of northern sea otters from the
Southcentral Alaska stock due to behavioral responses and/or TTS
associated with noise exposure. Although multiple instances of
harassment of individual sea otters are possible, we do not anticipate
that repeated harassment would affect individual sea otters in manners
not considered above.
The use of soft-start procedures, zone clearance prior to startup,
and shutdown zones is likely to decrease both the number of sea otters
exposed to sounds above Level A harassment thresholds and the exposure
time of any sea otters venturing into a Level A harassment zone. This
reduces the likelihood of hearing sensitivity losses that might impact
the health, reproduction, or survival of affected animals. Despite the
implementation of mitigation measures, it is anticipated that some sea
otters will experience Level A harassment via exposure to underwater
sounds above threshold criteria during impact and DTH pile-driving
activities. Due to sea otters' small body size and low profile in the
water, as well as the relatively large size of the Level A harassment
zone associated with these activities, we anticipate that sea otters
will at times avoid detection before entering Level A harassment zones
for those activities. Throughout the project, we estimate 170 instances
of take by Level A harassment of sea otters.
Determinations and Findings
Sea otters exposed to sound 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. Because activities will
occur during a limited amount of time and in a localized region, the
impacts associated with the project are likewise temporary and
localized. The anticipated effects are short-term behavioral reactions
and displacement of sea otters near active operations.
Sea otters that encounter the specified activity may exert more
energy than they would otherwise, due to temporary cessation of
feeding, increased vigilance, 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 TMC's request will reduce occurrences of
Level A harassment to the extent practicable, a small number of take by
Level A harassment are anticipated for impact and DTH pile-driving
activities, which have Level A harassment zone radii ranging in size
from 51.1 to 759.3 m (~168 to ~2,491 ft). The brevity of exposure of
sea otters to sounds at such levels will limit the degree of hearing
loss that may result from PTS experienced by these animals. We do not
anticipate that this type of hearing injury would result in effects
beyond what are considered above.
With the adoption of the mitigation measures incorporated in TMC's
request and subsequently required by this proposed IHA, anticipated
take was reduced.
Small Numbers
To assess whether the authorized incidental taking would be limited
to ``small numbers'' of marine mammals, the FWS uses a proportional
approach that considers whether the estimated number of marine mammals
to be subjected to incidental take is small relative to the population
size of the species or stock. Here, predicted levels of take were
determined based on the estimated density of sea otters in the project
area and ensonification zones developed using empirical evidence from
similar geographic areas.
We estimate that TMC's specified activities in the specified
geographic region will take no more than 347 sea otters during the 1-
year period of this proposed IHA (see Sum of Harassment from All
Sources). Take of 347 animals is 1.61 percent of the best available
estimate of the current Southcentral Alaska stock size of 21,617
animals (Esslinger et al. 2021) ((347/21,617) x 100[ap]1.61). We
propose a finding that the specified activities would take only a
``small number'' of sea otters of the Southcentral Alaska stock.
Negligible Impact
We propose a finding that any incidental take by harassment
resulting from the specified activities cannot be reasonably expected
to, and is not reasonably likely to, adversely affect sea otters
through effects on annual rates of recruitment or survival and will,
therefore, have no more than a negligible impact on the Southcentral
Alaska stock of northern sea otters. In making this finding, we
considered the best available scientific information, including the
biological and behavioral characteristics of the species; the most
recent information on species distribution and abundance within the
area of the specified activities; the current and expected future
status of the stock (including existing and foreseeable human and
natural stressors); the potential sources of disturbance caused by the
project; and the potential responses of marine mammals to this
disturbance. In addition, we reviewed applicant-provided materials,
information from our files and datasets, published reference materials,
and species experts.
Sea otters are likely to respond to planned activities with
temporary behavioral modification or temporary displacement. These
reactions are not anticipated to have consequences for the long-term
health, reproduction, or survival of affected animals. Most animals
will respond to disturbance by moving away from the source, which may
cause temporary interruption of foraging, resting, or other natural
behaviors. Affected animals are expected to resume normal behaviors
soon after exposure with no lasting consequences. Some animals 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 extend over a period of time
sufficiently long so as to result in effects not considered in our
analyses.
Sea otters may move in and out of the project area during pile
driving activities, leading to as many as 347 individuals experiencing
one day of exposure. However, it is possible that an individual may
enter ensonification areas more than once during the project. At most,
if an individual sea otter enters an ensonification area every day that
pile driving occurs, the sea otter would be exposed to pile driving and
marine construction noise for up to 204 days. However, the areas that
will experience noise greater than Level A or Level B
[[Page 45802]]
thresholds due to pile driving are small (a maximum of just over 2
km\2\), and on the majority of work days these areas will be below 0.1
km\2\. This limits the number of days on which an individual animal
might be exposed over the duration of the project. 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,
the sea otters' ears will not be exposed to continuous noise;
therefore, the amount of time it may take for permanent hearing loss to
occur is considerably longer than for mammals whose heads remain
primarily under water.
The total number of animals affected, and severity of impact are
not sufficient to change the current population dynamics at the stock
scale. Although the specified activities may result in approximately
631 incidental takes of up to 347 sea otters from the Southcentral
Alaska stock, we do not expect this level of harassment to affect
annual rates of recruitment or survival or result in adverse effects on
the stock.
Our proposed finding of negligible impact applies to incidental
take associated with the specified activities as mitigated by the
avoidance and minimization measures identified in TMC's mitigation and
monitoring plan. These mitigation measures are designed to minimize
interactions with and impacts to sea otters. These measures, as well as
monitoring and reporting procedures, are a necessary component of the
proposed IHA and required for valid findings. For these reasons, we
propose a finding that the specified project will have a negligible
impact on the Southcentral Alaska stock of northern sea otters.
Impact on Subsistence Use
The project will not preclude access to harvest areas or interfere
with the availability of sea otters for harvest. Additionally, the
planned activities are located within the City of Seward, Alaska, where
firearm use is prohibited. We therefore propose a finding that TMC's
anticipated harassment will not have an unmitigable adverse impact on
the availability of any stock of northern sea otters for taking for
subsistence uses. In making this proposed finding, we considered the
timing and location of the planned activities and the timing and
location of subsistence harvest activities in the project area.
Least Practicable Adverse Impact
We propose to find that the mitigation measures required by this
proposed IHA will effect the least practicable adverse impact on the
sea otter stocks from any incidental take likely to occur in
association with the specified activities. In making this finding, we
considered the biological characteristics of sea otters, the nature of
the specified activities, the potential effects of the activities on
sea otters, the documented impacts of similar activities on sea otters,
and alternative mitigation measures.
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 effectiveness
of these measures once successfully implemented. 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). We assessed whether
any additional, practicable requirements could be implemented to
further reduce effects, but did not identify any.
TMC incorporated the following mitigation measures into its
request:
<bullet> Using the smallest diameter piles practicable while
minimizing the overall number of piles;
<bullet> Using a project design that does not include blasting;
<bullet> Using a hammer cushion during impact pile driving;
<bullet> Minimizing the use of the impact hammer to the extent
possible by using a vibratory hammer to advance piles as deeply as
possible;
<bullet> Employing a bubble curtain for all 60- and 72-in piles and
for 48-in dolphin piles to reduce noise impacts;
<bullet> Development of a marine mammal monitoring and mitigation
plan;
<bullet> Establishment of shutdown and monitoring zones;
<bullet> Visual mitigation monitoring by designated PSOs;
<bullet> Site clearance before startup;
<bullet> Soft-start procedures; and
<bullet> Shutdown procedures.
The sound source levels, and associated sound isopleth radii and
shutdown zones, include reductions from bubble curtains. The FWS has
not identified any additional (i.e., not already incorporated into
TMC's request) mitigation or monitoring measures that are practicable
and would further reduce potential impacts to sea otters and their
habitat.
Monitoring and Reporting
The purposes of the monitoring requirements are to document and
provide data for assessing the effects of specified activities on sea
otters; to ensure that the specified activities impacts remain
consistent with MMPA standards; and to detect any unanticipated effects
on the species. Monitoring plans include steps to document when and how
sea otters are encountered, as well as and their numbers and behaviors
during these encounters. This information allows the FWS to measure
encounter rates and trends and to estimate numbers of animals
potentially affected. To the extent possible, monitors will record
group size, age, sex, reaction, interaction duration, and closest
approach to the project activity.
As described in the request, monitoring activities would be
formally summarized and reported. TMC would submit monthly reports for
all months during which noise-generating work takes place as well as a
final monitoring report that must submitted no later than 90 days after
the IHA expiration.
References Cited
A list of the references cited in this notice may be found at
<a href="https://www.regulations.gov">https://www.regulations.gov</a> under Docket No. FWS-R7-ES-2025-0056.
Required Determinations
National Environmental Policy Act
We have prepared a draft environmental assessment in accordance
with the National Environmental Policy Act (NEPA; 42 U.S.C. 4321 et
seq.). We have preliminarily concluded that issuing the proposed IHA
would not significantly affect the quality of the human environment
and, thus, preparation of an environmental impact statement for this
proposed IHA 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
Under the Endangered Species Act (ESA; 16 U.S.C. 1536(a)(2)), 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. The specified activities would occur entirely within
the range of the Southcentral Alaska stock of northern sea otters,
which is not listed as threatened or
[[Page 45803]]
endangered under the ESA. The authorization of incidental take of
northern sea otters and the measures included in the proposed IHA would
have no effect on other listed species or their designated critical
habitat.
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 Alaska Native Claims Settlement Act (ANCSA) corporations 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
Tribal organizations and communities. 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 Order 13175 (January 9, 2000);
(4) Department of the Interior Secretary's Orders 3206 (June 5,
1997), 3225 (January 19, 2001), 3317 (December 1, 2011), and 3342
(October 21, 2016);
(5) The Alaska Government-to-Government Policy (a departmental
memorandum issued January 18, 2001); and
(6) the Department of the Interior's policies on consultation with
Alaska Native Tribes and organizations.
We have evaluated possible effects of the specified activities on
federally recognized Alaska Native Tribes and organizations. The FWS
has determined that, due to this project's locations and activities,
the Tribal organizations and communities near Seward, Alaska, as well
as relevant ANCSA corporations, will not be impacted. Regardless, we
will be reaching out to the Tribal organizations and ANCSA corporations
to inform them of the availability of this proposed IHA and offer them
the opportunity to consult.
We invite continued discussion, either about the project and its
impacts or about our coordination and information exchange, throughout
the IHA process.
Paperwork Reduction Act
This rule does not contain any new collection of information that
requires approval by the Office of Management and Budget (OMB) under
the Paperwork Reduction Act of 1995 (44 U.S.C. 3501 et seq.). The OMB
has previously approved the information collection requirements
associated with IHAs and assigned OMB control number 1018-0194 (expires
August 31, 2026). An agency may not conduct or sponsor, and a person is
not required to respond to, a collection of information unless it
displays a currently valid OMB control number.
Proposed Authorization
We propose to authorize the nonlethal, incidental take by Level A
harassment and Level B harassment of 347 northern sea otters from the
Southcentral Alaska stock. Authorized take may be caused by pile
driving and marine construction activities conducted by TMC in Seward,
Alaska, for a period of up to one year from the date of finalization.
We do not anticipate or authorize any lethal take to sea otters
resulting from these activities.
A. General Conditions for This IHA
(1) Activities must be conducted in the manner described in the
April 7, 2025, revised request from TMC for an IHA and in accordance
with all applicable conditions and mitigation measures. The taking of
sea otters whenever the required conditions, mitigation, monitoring,
and reporting measures are not fully implemented as required by the IHA
is prohibited. Failure to follow the measures specified both in the
revised request and within this proposed authorization may result in
the modification, suspension, or revocation of the IHA.
(2) If project activities cause unauthorized take (i.e., a form of
take other than Level A harassment or Level B harassment, or take of
one or more sea otters through methods not described in the IHA), TMC
must take the following actions:
(i) Cease its activities immediately (or reduce activities to the
minimum level necessary to maintain safety);
(ii) Report the details of the incident to the FWS within 48 hours;
and
(iii) Suspend further activities until the FWS has reviewed the
circumstances and determined whether additional mitigation measures are
necessary to avoid further unauthorized taking.
(3) All operations managers, vehicle operators, and machine
operators must receive a copy of this IHA and maintain access to it for
reference at all times during project work. These personnel must
understand, be fully aware of, and be capable of implementing the IHA's
conditions at all times during project work.
(4) This IHA will apply to activities associated with the specified
project as described in this document and in TMC's revised request.
Changes to the specified project without prior authorization may
invalidate the IHA.
(5) TMC's revised request is approved and fully incorporated into
this IHA unless exceptions are specifically noted herein. The request
includes:
(i) TMC's original request for an IHA, dated November 8, 2024;
(ii) Additional details, provided January 10, 2025;
(iii) An updated application, provided April 7, 2025; and
(iv) Marine Mammal Mitigation and Monitoring Plan.
(6) Operators will allow FWS personnel or the FWS's designated
representative to visit project worksites to monitor for impacts to sea
otters and subsistence uses of sea otters at any time throughout
project activities so long as it is safe to do so. ``Operators'' are
all personnel operating under TMC's authority, including all
contractors and subcontractors.
B. Avoidance and Minimization
(1) Construction activities must be conducted using equipment that
generates the lowest practicable levels of underwater sound within the
range of frequencies audible to sea otters.
(2) During all pile-installation activities, regardless of
predicted sound levels, a physical interaction shutdown zone of 10 m
(33 ft) must be enforced. If a sea otter enters the shutdown zone, in-
water activities must be delayed until either the animal has been
visually observed outside the shutdown zone, or 15 minutes have elapsed
since the last observation time without redetection of the animal.
(3) If the impact driver has been idled for more than 30 minutes,
an initial set of three strikes from the impact driver must be
delivered at reduced energy, followed by a 1-minute waiting period,
before full-powered proofing strikes.
(4) In-water activity must be conducted in daylight. If
environmental conditions prevent visual detection of sea otters within
the shutdown zone, in-water activities must be stopped until visibility
is regained.
C. Mitigation Measures for Vessel Operations
Vessel operators must take every precaution to avoid harassment of
sea otters when a vessel is operating near these animals. The applicant
must carry out the following measures:
(1) Vessels must remain at least 500 m (0.3 mi) from rafts of sea
otters unless safety is a factor. Vessels must reduce
[[Page 45804]]
speed and maintain a distance of 100 m (328 ft) from all sea otters
unless safety is a factor.
(2) Vessels must not be operated in such a way as to separate
members of a group of sea otters from other members of the group and
must avoid alongshore travel in shallow water (<20 m) whenever
practicable.
(3) When weather conditions require, such as when visibility drops,
vessels must adjust speed accordingly to avoid the likelihood of injury
to sea otters.
(4) Vessel operators must be provided written guidance for avoiding
collisions and minimizing disturbances to sea otters. Guidance will
include all measures identified in this section.
D. Monitoring
(1) Operators shall work with protected species observers (PSOs) to
apply mitigation measures and shall recognize the authority of PSOs up
to and including stopping work, except where doing so poses a
significant safety risk to personnel.
(2) Duties of the PSOs include watching for and identifying sea
otters, recording observation details, documenting presence in any
applicable monitoring zone, identifying and documenting potential
harassment, and working with operators to implement all appropriate
mitigation measures.
(3) A sufficient number of PSOs will be available to meet the
following criteria: 100 percent monitoring of exclusion zones during
all daytime periods of underwater noise-generating work; a maximum of 4
consecutive hours on watch per PSO; a maximum of approximately 12 hours
on watch per day per PSO.
(4) All PSOs will complete a training course designed to
familiarize individuals with monitoring and data collection procedures.
A field crew leader with prior experience as a sea otter observer will
supervise the PSO team. Initially, new or inexperienced PSOs will be
paired with experienced PSOs so that the quality of marine mammal
observations and data recording is kept consistent. Resumes for
candidate PSOs will be made available for the FWS to review.
(5) Observers will be provided with reticule binoculars (7x50 or
better), big-eye binoculars or spotting scopes (30x), inclinometers,
and range finders. Field guides, instructional handbooks, maps, and a
contact list will also be made available.
(6) Observers will collect data using the following procedures:
(i) All data will be recorded onto a field form or database.
(ii) Global positioning system data, sea state, wind force, and
weather will be collected at the beginning and end of a monitoring
period, every hour in between, at the change of an observer, and upon
sightings of sea otters.
(iii) Observation records of sea otters will include date; time;
the observer's locations, heading, and speed (if moving); weather;
visibility; number of animals; group size and composition (adults/
juveniles); and the location of the animals (or distance and direction
from the observer).
(iv) Observation records will also include initial behaviors of the
sea otters, descriptions of project activities and underwater sound
levels being generated, the position of sea otters relative to
applicable monitoring and mitigation zones, any mitigation measures
applied, and any apparent reactions to the project activities before
and after mitigation.
(v) For all sea otters in or near a mitigation zone, observers will
record the distance from the sound source to the sea otter upon initial
observation, the encounter duration, and the distance at last
observation to monitor cumulative sound exposures.
(vi) Observers will note any instances of animals lingering close
to or traveling with vessels for prolonged periods of time.
(7) Monitoring of the shutdown zone must continue for 30 minutes
following completion of pile installation.
E. Measures To Reduce Impacts to Subsistence Users
(1) Prior to conducting the work, TMC will take the following steps
to reduce potential effects on subsistence harvest of sea otters:
(i) Avoid work in areas of known sea otter subsistence harvest;
(ii) Discuss the planned activities with subsistence stakeholders
including Southcentral Alaska villages and traditional councils;
(iii) Identify and work to resolve concerns of stakeholders
regarding the project's effects on subsistence hunting of sea otters;
and
(iv) If any concerns remain, develop a POC in consultation with the
FWS and subsistence stakeholders to address these concerns.
F. Reporting Requirements
(1) The applicant, TMC, must notify the FWS at least 48 hours prior
to commencement of activities.
(2) Monthly reports will be submitted to the FWS's Marine Mammal
Management office (MMM) for all months during which noise-generating
work takes place. The monthly report will contain and summarize the
following information: dates, times, weather, and sea conditions
(including the Beaufort Scale sea state and wind force conditions) when
sea otters were sighted; the number, location, distance from the sound
source, and behavior of the sea otters; the associated project
activities; and a description of the implementation and effectiveness
of mitigation measures with a discussion of any specific behaviors the
sea otters exhibited in response to mitigation.
(3) A final report will be submitted to the FWS's MMM within 90
days after work completion or IHA expiration. The report will include:
(i) A summary of monitoring efforts (hours of monitoring,
activities monitored, number of PSOs, and, if requested by the FWS, the
daily monitoring logs).
(ii) A description of all project activities, along with any
additional work yet to be done. Factors influencing visibility and
detectability of marine mammals (e.g., sea state, number of observers,
and fog and glare) will be discussed.
(iii) A description of the factors affecting the presence and
distribution of sea otters (e.g., weather, sea state, and project
activities). An estimate will be included of the number of sea otters
exposed to noise at received levels corresponding to Level A harassment
or Level B harassment (based on visual observation).
(iv) A description of changes in sea otter behavior resulting from
project activities and any specific behaviors of interest.
(v) A discussion of the mitigation measures implemented during
project activities and their observed effectiveness for minimizing
impacts to sea otters. Sea otter observation records will be provided
to the FWS in the form of electronic database or spreadsheet files.
(4) Injured, dead, or distressed sea otters that are not associated
with project activities (e.g., animals known to be from outside the
project area, previously wounded animals, or carcasses with moderate to
advanced decomposition or scavenger damage) must be reported to the FWS
within 24 hours of the discovery to either the FWS's MMM Office (1-800-
362-5148, business hours); or the Alaska SeaLife Center in Seward (1-
888-774-7325, 24 hours a day), or both. Photographs, video, location
information, or any other available documentation must be provided to
the FWS.
(5) All reports shall be submitted by email to
<a href="/cdn-cgi/l/email-protection#c78190f098aaaaaa98b5a2b7a8b5b3b487a1b0b4e9a0a8b1"><span class="__cf_email__" data-cfemail="1c5a4b2b43717171436e796c736e686f5c7a6b6f327b736a">[email protected]</span></a>.
[[Page 45805]]
(6) TMC must notify the FWS upon project completion or end of the
work season.
Request for Public Comments
If you wish to comment on this proposed authorization, the
associated draft environmental assessment, or related documents, you
may submit your comments by either of the methods described in
ADDRESSES. Please identify the document(s) to which your comments
pertain, make your comments as specific as possible, confine them to
issues pertinent to the proposed authorization, 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 before the close
of the comment period (see DATES). The FWS does not anticipate
extending the public comment period beyond the 30 days required under
section 101(a)(5)(D)(iii) of the MMPA.
Comments, including names and street addresses of respondents, will
become part of the administrative record for this proposal. Before
including your address, telephone number, email address, or other
personal identifying information in your comment, be advised that your
entire comment, including your personal identifying information, may be
made publicly available at any time. While you can ask us in your
comments to withhold from public review your personal identifying
information, we cannot guarantee that we will be able to do so.
Peter Fasbender,
Assistant Regional Director for Fisheries and Ecological Services,
Alaska Region, U.S. Fish and Wildlife Service.
[FR Doc. 2025-18348 Filed 9-22-25; 8:45 am]
BILLING CODE 4333-15-P
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