[Federal Register Volume 88, Number 213 (Monday, November 6, 2023)]
[Notices]
[Pages 76225-76241]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-24428]


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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

[Docket No. FWS-R7-ES-2023-0101; FXES111607MRG01-234-FF07CAMM00]


Marine Mammals; Incidental Take During Specified Activities; 
Proposed Incidental Harassment Authorization for Southcentral Alaska 
Stock of Northern Sea Otters in Cordova, Alaska; Draft Environmental 
Assessment

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Notice of receipt of application; proposed incidental 
harassment authorization; 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 City of Cordova, Alaska, propose to authorize nonlethal 
incidental take by harassment of small numbers of the Southcentral 
Alaska stock of northern sea otters (Enhydra lutris kenyoni) for 1 year 
from the date of issuance of the incidental harassment authorization. 
The applicant has requested this authorization for take by harassment 
that may result from activities associated with pile driving and marine 
construction activities in Cordova, Alaska. We estimate that this 
project may result in the nonlethal incidental take by harassment of up 
to 82 northern sea otters from the Southcentral stock. This proposed 
authorization, if finalized, will be for up to 30 takes of 5 northern 
sea otters by Level A harassment and 790 takes of 77 northern sea 
otters by Level B harassment. No lethal take is requested, or expected, 
and no such take will be authorized.

DATES: Comments on this proposed incidental harassment authorization 
and the accompanying draft environmental assessment must be received by 
December 6, 2023.

ADDRESSES: 
    Document availability: You may view this proposed incidental 
harassment authorization, the application package, supporting 
information, draft environmental assessment, and the list of references 
cited herein at https://www.regulations.gov under Docket No. FWS-R7-ES-
2023-0101. Alternatively, 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:
     U.S. mail: Public Comments Processing, Attn: Docket No. 
FWS-R7-ES-2023-0101, U.S. Fish and Wildlife Service, MS: PRB (JAO/3W), 
5275 Leesburg Pike, Falls Church, VA 22041-3803.
     Electronic submission: https://www.regulations.gov. Follow 
the instructions for submitting comments to Docket No. FWS-R7-ES-2023-
0101.
    We will post all comments at https://www.regulations.gov. 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: Sierra Franks, by email at 
[email protected] or by telephone at 01-800-362-5148. U.S. Fish 
and Wildlife Service, MS 341, 1011 East Tudor Road, Anchorage, AK 
99503. 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 (``Service'' or ``we''). According 
to the MMPA, the Service shall allow this incidental taking 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:
    (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 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

[[Page 76226]]

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 impacts.'' We recognize ``small numbers'' 
and ``negligible impacts'' 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 February 28, 2023, the City of Cordova (hereafter also known as 
``the City'' or ``the applicant'') submitted a request to the Service 
for authorization to take by Level A and Level B harassment a small 
number of northern sea otters (Enhydra lutris kenyoni) (hereafter, 
``sea otters'' or ``otters'' unless another species is specified) from 
the Southcentral Alaska stock. The Service sent requests for additional 
information on March 24, May 16, and May 30, 2023. We received updated 
versions of the request on April 27, May 18, and June 8, 2023. The 
Service determined the June 8, 2023, application to be adequate and 
complete. The applicant expects take by harassment may occur during the 
construction of replacements and improvements to the harbor facilities 
in Cordova, Alaska.

Description of Specified Activities and Specified Geographic Region

    The specified activity (hereafter, ``project'') will include the 
installation and removal of piles and the installation of a bulkhead to 
rebuild the facilities of the South Harbor in Cordova, Alaska (figure 
1) between September 2023 and June 2024. The City will remove 130 
existing 30-centimeter (cm) (12-inch (in)) diameter timber piles and 61 
existing 30-cm (12-in) diameter steel piles and will permanently 
install the following types of piles: 155 41-cm (16-in) diameter steel 
piles, 140 46-cm (18-in) diameter steel piles, 30 76-cm (30-in) 
diameter steel piles, and 140 steel 41-cm x 226-cm (16-in x 89-in) H 
piles. Construction will also include the installation and removal of 
131 61-cm (24-in) diameter temporary steel piles. Components of the 
harbor that will be installed out of water include approximately 350 
meters (m) (1,150 feet (ft)) of bulkhead wall supported by H piles; 
main walk floats, end floats, and stall floats; 447 slips; pedestrian 
gangways; other float components including bull rail, floating fenders, 
mooring cleats, electricity connections, potable water service, fire 
suppression waterlines, lighting, wireless connections, and hand rails; 
and an uplands service area with parking lot expansion, greenspace, and 
stormwater treatment capabilities. Pile-driving activities will occur 
over 170 non-consecutive days for approximately 434 hours over 1 year 
from date of issuance of the IHA. If the IHA is issued after the 
applicant's intended start date in September 2023, its 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 piles will be removed with the 
vibratory hammer. Materials and equipment will be transported via 
barges, and workers will be transported to and from the barge work 
platform via skiff.
    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.

[[Page 76227]]

[GRAPHIC] [TIFF OMITTED] TN06NO23.060

Description of Marine Mammals in the Specified Geographic Region

Sea Otter Biology

    There are three sea otter stocks in Alaska: Southeast Alaska stock, 
Southcentral Alaska stock, and the Southwest Alaska stock. Only the 
Southcentral Alaska stock is represented in the project area. Detailed 
information about the biology of this stock can be found in the most 
recent Southcentral Alaska stock assessment report (USFWS 2023), which 
can be found at https://www.regulations.gov/document/FWS-R7-ES-2022-0155-0012 and was announced in the Federal Register at 88 FR 53510, 
August 8, 2023.
    Sea otters may be distributed anywhere within the specified project 
area 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 (USFWS 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 venture 
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). 
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 
maintain 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, Tinker and Estes 1996). 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 
(hr) (km/hr; 3.4 mi/hr) (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, the eastern 
Kenai Peninsula coast, and Kachemak Bay (USFWS 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) Prince William Sound by aerial transects flown 
at 91 m (298.56 ft) of altitude. The combined estimates of the three 
regions resulted in approximately 21,617 (SE = 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). In aerial sea otter 
abundance surveys of Prince William Sound, Weitzman and Esslinger 
(2015) found a

[[Page 76228]]

density of 21.15 sea otters/km\2\ in the Orca Inlet subregion. Multiple 
local sources of data (Greenwood 2022; Prince William Sound Science 
Center 2022; Schinella 2022, 2023; Solstice Alaska Consulting Inc. 
2022) indicate a higher density within the Cordova Harbor-approximately 
20 sea otters at any given time within the 0.18 km\2\ area of the 
harbor, or a density of 111.11 sea otters/km\2\. We utilized both 
sources of data and applied the published density for areas outside the 
harbor and the local data for areas within the harbor.

Potential Impacts of the Specified Activities on Marine Mammals

Effects of Noise on Sea Otters

    We characterized ``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'' or ``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 will fall 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 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 0.125-1 kHz were between 
116-101 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. 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 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 sensitivity of hearing 
(i.e., a permanent threshold shift (PTS) (NMFS 2018)). 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 (SELCUM) 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). Southall and colleagues (2019) predict 
PTS for sea otters, which are included in the ``other marine 
carnivores'' category, will occur at 232 dB peak or 203 dB 
SELCUM (db SEL) for impulsive underwater sound and 219 dB 
SEL 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 at 
approximately 170 dB SEL (136 dB, 60 minutes (min)) and 178 dB SEL (148 
dB, 15 min). 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 (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 (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 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 to 160 dB, and most marine mammals showed some, 
albeit variable, responses to sound between 140 to 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 of 
140, 160, and 180 dB, respectively.
    We have evaluated these thresholds and determined that the Level B 
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

[[Page 76229]]

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 Service has set 160 dB of received underwater sound as a 
threshold for Level B harassment by disturbance for sea otters for this 
proposed IHA. Exposure to unmitigated 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 Service as Level B 
harassment. Thresholds for Level A harassment (which entails the 
potential for injury) will be 232 dB peak or 203 dB SEL for impulsive 
sounds and 219 dB SEL for continuous sounds (table 1).
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.
    Southall et al. (2019) have developed TTS and PTS thresholds for 
other marine carnivores, which include sea otters, for airborne 
impulsive and non-impulsive sounds (table 1). For project activities 
that create only airborne sounds, such as pile driving on land, the 
sound levels are significantly below the TTS thresholds developed by 
Southall et al. 2019. NMFS has previously used ``a generalized acoustic 
threshold based on received level to estimate the onset of behavioral 
harassment'' (April 10, 2019, 84 FR 14314). NMFS predicts that all 
other pinniped species that are not harbor seals will be behaviorally 
harassed when exposed to airborne sounds above 100 dB re 20 micropascal 
([micro]Pa) (84 FR 14314). Since otariid pinnipeds are the closest 
available physiological and anatomical proxy for sea otters, we used 
the NMFS criteria for pinniped harassment from exposure to airborne 
sound to estimate take by Level B harassment from pile driving on 
shore.

   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
  [Values are weighted for other marine carnivores' hearing thresholds and given in cumulative sound exposure level (SELCUM dB re (20 [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).]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                        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
--------------------------------------------------------------------------------------------------------------------------------------------------------

Evidence From Sea Otter Studies

    Sea otters may be more resistant to the effects of sound 
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, 3-4 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

[[Page 76230]]

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). Male and 
female 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 findings 
suggest that the large portion of the day 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. 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 boat 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 Orca Inlet 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, 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 (i.e., 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, are less likely to be displaced.

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 boat 
traffic faced a substantial (18 percent) estimated decrease in energy 
intake (Williams et al. 2006). In severe cases, such disturbance 
effects could 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 noise 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 noise 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 boat 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.
    Vessel strike has been documented as a cause of death across all 
three stocks of northern sea otters in Alaska. Since 2002, the Service 
has conducted 1,433 sea otter necropsies to determine cause of death, 
disease incidence, and the general health status of sea otters in 
Alaska. Vessel strike or blunt trauma was identified as a definitive or

[[Page 76231]]

presumptive cause of death in 65 cases (4 percent) (USFWS 2020). In 
most of these cases, trauma was determined to be the ultimate cause of 
death; however, there was a contributing factor, such as disease or 
biotoxin exposure, which incapacitated the sea otter and made it more 
vulnerable to vessel strike (USFWS 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 authorization portion of this document under 
Avoidance and Minimization.
    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. As noted above, 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, sea otter responses to vessels may be influenced by 
the 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 within 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 findings indicate that sea otters may adjust their 
responses to vessel activities depending on the level of activity. 
Vessel activity during the project includes the transit of two barges 
for materials and construction, both of which will remain on site, 
mostly stationary, to support the work; additionally, a skiff will be 
used during the project for transporting workers short distances to 
support construction activities. Vessels will not be used extensively 
or over a long duration during the planned work; therefore, we do not 
anticipate that sea otters will experience changes in behavior 
indicative of tolerance or habituation.

Effects on Sea Otter Habitat and Prey

    Physical and biological features of habitat essential to the 
conservation of sea otters include the benthic invertebrates that sea 
otters eat and the shallow rocky areas and kelp 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.
    Industrial activities, such as pile driving, may generate in-water 
noise at levels that can temporarily displace sea otters from important 
habitat and impact 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.) (Tinker and 
Estes 1996, 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).
    Several studies have addressed the effects of noise on 
invertebrates (Tidau and Briffa 2016, Carroll et al. 2017). Behavioral 
changes, such as an increase in lobster (Homarus 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). 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 planned 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 sounds produced by each 
component of the planned 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

[[Page 76232]]

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.

Potential Impacts of the Specified Activities on Subsistence Uses

    The planned specified activities will occur near marine subsistence 
harvest areas used by Alaska Natives from Cordova and the surrounding 
areas. Since 2013, there have been 914 sea otters harvested by hunters 
from the Cordova area, and most of those were taken prior to 2016. From 
2018 through 2022, 236 sea otters were harvested from the Cordova area.
    The planned project would occur within the Cordova city limits, 
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 Service 
will notify potentially affected communities and stakeholders of the 
public comment period on this proposed IHA so they have an opportunity 
to share any questions, concerns, or potential conflicts regarding 
subsistence use in those areas. If any conflicts are identified in the 
future, the applicant 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 definitions of three potential types of take of 
sea otters. The Service does not anticipate and is not authorizing 
lethal take as a part of this proposed IHA; however, the definitions of 
these take types are provided for context and background:
    Lethal Take--Human activity may result in biologically significant 
impacts to sea otters. In the most serious interactions, human actions 
can result in mortality of sea otters.
    Level A Harassment--Human activity may result in the injury of 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 behavioral patterns, including, but not 
limited to, migration, breathing, nursing, feeding, or sheltering. 
Changes in behavior that disrupt biologically significant behaviors or 
activities for the affected animal are indicative of take by Level B 
harassment under the MMPA.
    The Service has identified the following sea otter behaviors as 
indicative of possible Level B harassment:
     Swimming away at a fast pace on belly (i.e., porpoising);
     Repeatedly raising the head vertically above the water to 
get a better view (spyhopping) while apparently agitated or while 
swimming away;
     In the case of a pup, repeatedly spyhopping while hiding 
behind and holding onto its mother's head;
     Abandoning prey or feeding area;
     Ceasing to nurse and/or rest (applies to dependent pups);
     Ceasing to rest (applies to independent animals);
     Ceasing to use movement corridors;
     Ceasing mating behaviors;
     Shifting/jostling/agitation in a raft so that the raft 
disperses;
     Sudden diving of an entire raft; or
     Flushing animals off a haulout.
    This list is not meant to encompass all possible behaviors; other 
behavioral responses may equate to take by 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 Service does not 
view such minor changes in behavior as indicative of a take by Level B 
harassment.

Calculating Take

    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 or Level B harassment due to exposure 
to underwater noise. Likewise, we assumed that all animals exposed to 
airborne sound levels that meet the acoustic exposure criteria in 
Exposure Thresholds will experience take by Level B harassment due to 
exposure to in-air 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 otters present in the ensonification zones 
using density information generated by Weitzman and Esslinger (2015), 
as well as local sources of data that indicated a higher density of sea 
otters within the harbor (Greenwood 2022; Prince William Sound Science 
Center 2022; Schinella 2022, 2023; Solstice Alaska Consulting Inc. 
2022).
    The project can be divided into five major components: DTH pile 
driving, vibratory pile driving, impact pile driving, skiff use to 
support construction, and pile driving on land. Each of these 
components will generate a different type of noise. Vibratory pile 
driving and the use of skiffs will produce nonimpulsive or continuous 
noise; impact pile driving will produce impulsive noise; and DTH pile 
driving 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 tables 2 
through 7. We used 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, and empirical data from the 
proxy projects were used to determine the distance at which sound 
levels would attenuate to Level B harassment thresholds (table 1). 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. 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 
determine the distance at which sound levels attenuate to 160 dB re 1 
[micro]Pa. Due to limited data of underwater sound pressure levels from 
DTH pile driving as well as differences in how PTS and TTS thresholds 
are calculated, the resultant Level A isopleths for DTH pile driving 
are larger than the Level B isopleths.

[[Page 76233]]



 Table 2--Summary of Sound Level, Timing of Sound Production, Distance From Sound Source to Below Level A Harassment and Level B Harassment Thresholds,
      Days of Impact, Sea Otters in Level A and Level B Harassment Ensonification Area, and Total Otters Expected To Be Harassed Through Behavioral
                                                          Disturbance by Vibratory Pile Driving
--------------------------------------------------------------------------------------------------------------------------------------------------------
                               30 to 61-cm (12-  30 to 61-cm (12-
                                 in to 24-in)      in to 24-in)     61-cm (24-inch)   61-cm (24-inch)   41-cm (16-in)    46-cm (18-in)    76-cm (30-in)
          Pile size             existing timber   existing steel       template      template removal   permanent pile   permanent pile   permanent pile
                                 pile removal      pile removal      installation                        installation     installation     installation
--------------------------------------------------------------------------------------------------------------------------------------------------------
Total number of piles........  130.............  61..............  61..............  61..............  155............  70.............  30.
                                                ----------------------------------------------------------------------------------------
Sound level..................  162 dB re 1                                 161 dB re 1 [micro]Pa at 10 m (RMS)                           161.9 dB re 1
                                [micro]Pa at 10                                                                                           [micro]Pa at
                                m (RMS).                                                                                                  10 m (RMS).
                                                ----------------------------------------------------------------------------------------
Source.......................  NMFS 2023.......                                   NAVFAC\a\ 2013, 2015                                   Denes et al.
                                                                                                                                          2016.
                                                ----------------------------------------------------------------------------------------
Timing per pile..............  10 minutes/pile.  10 minutes/pile.  10 minutes/pile.  10 minutes/pile.  15 minutes/pile  20 minutes/pile  30 minutes/
                                                                                                                                          pile.
Maximum number of piles per    25..............  25..............  6...............  10..............  10.............  10.............  6.
 day.
Maximum number of days of      6...............  3...............  11..............  7...............  16.............  7..............  5.
 activity.
                              --------------------------------------------------------------------------------------------------------------------------
Sea otter density............                                                   111.11 sea otters/km\2\
                              --------------------------------------------------------------------------------------------------------------------------
Distance to below Level A      0.9 meters......  0.8 meters......  0.4 meters......  0.4 meters......  0.5 meters.....  0.7 meters.....  0.7 meters.
 harassment threshold.
Level A area (km\2\).........  0.0000..........  0.0000..........  0.0000..........  0.0000..........  0.0000.........  0.0000.........  0.0000.
Potential sea otters affected  0...............  0...............  0...............  0...............  0..............  0..............  0.
 by Level A sound per day.
Potential sea otters affected  0...............  0...............  0...............  0...............  0..............  0..............  0.
 by Level A sound per day
 (rounded).
Total potential Level A        0...............  0...............  0...............  0...............  0..............  0..............  0.
 harassment events.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Distance to below Level B      14 meters.......  12 meters.......  12 meters.......  12 meters.......  12 meters......  12 meters......  13 meters.
 harassment threshold.
Level B area (km\2\).........  0.0003..........  0.0002..........  0.0002..........  0.0002..........  0.0002.........  0.0002.........  0.0002.
Potential sea otters affected  0.0333..........  0.0222..........  0.0222..........  0.0222..........  0.0222.........  0.0222.........  0.0222.
 by Level B sound per day.
Potential sea otters affected  1...............  1...............  1...............  1...............  1..............  1..............  1.
 by Level B sound per day
 (rounded).
Total potential Level B        6...............  3...............  11..............  7...............  16.............  7..............  5.
 harassment events.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Naval Facilities Engineering Command.


    Table 3--Summary of Sound Level, Timing of Sound Production, Distance From Sound Source to Below Level A
  Harassment Thresholds, Days of Impact, Sea Otters in Level A Harassment Ensonification Area, and Total Otters
                        Expected To Be Taken by Level A Harassment by Impact Pile Driving
----------------------------------------------------------------------------------------------------------------
                                       41-cm (16-in) permanent  46-cm (18-in) permanent  76-cm (30-in) permanent
              Pile size                   pile  installation       pile  installation       pile  installation
----------------------------------------------------------------------------------------------------------------
Total number of piles................  73.....................  35.....................  20.
Sound level..........................  168.3 dB (SEL)/181.1 dB  168.3 dB (SEL)/181.1 dB  177 dB (SEL)/190 dB
                                        (RMS)/192.8 dB (peak)    (RMS)/192.8 dB (peak)    (RMS)/210 dB (peak) re
                                        re 1 [micro]Pa at 10 m.  re 1 [micro]Pa at 10 m.  1 [micro]Pa at 10 m.
                                      --------------------------------------------------
Source...............................                  Denes et al. 2016                 NMFS 2023.
                                      --------------------------------------------------
Timing per pile......................  20 minutes/pile; 240     20 minutes/pile; 240     20 minutes/pile; 360
                                        strikes/pile.            strikes/pile.            strikes/pile.
Maximum number piles per day.........  6......................  6......................  6.
Maximum number of days of activity...  13.....................  6......................  4.
                                      --------------------------------------------------------------------------
Sea otter density....................                           111.11 sea otters/km\2\
                                      --------------------------------------------------------------------------
Distance to below Level A harassment   5.2 meters.............  5.2 meters.............  25.9 meters.
 threshold.
Total Level A area (km\2\)...........  0.0001.................  0.0001.................  0.0021.
Level A area (km\2\) after excluding   0......................  0......................  0.0018.
 10-m shutdown zone (0.0003 km\2\).
Potential sea otters affected by       0......................  0......................  0.2000.
 Level A sound per day.
Potential sea otters affected by       0......................  0......................  1.
 Level A sound per day (rounded).
Total potential Level A harassment     0......................  0......................  4.
 events.
----------------------------------------------------------------------------------------------------------------


[[Page 76234]]


    Table 4--Summary of Sound Level, Timing of Sound Production, Distance From Sound Source to Below Level B
 Harassment Thresholds, Days of Impact, Sea Otters in Level B Ensonification Area, and Total Otters Expected To
                              Be Taken by Level B Harassment by Impact Pile Driving
----------------------------------------------------------------------------------------------------------------
                                       41-cm (16-in) permanent  46-cm (18-in) permanent  76-cm (30-in) permanent
              Pile size                   pile installation        pile installation        pile installation
----------------------------------------------------------------------------------------------------------------
Total number of piles................  73.....................  35.....................  20.
Sound level..........................  168.3 dB (SEL)/181.1 dB  168.3 dB (SEL)/181.1 dB  177 dB (SEL)/190 dB
                                        (RMS)/192.8 dB (peak)    (RMS)/192.8 dB (peak)    (RMS)/210 dB (peak) re
                                        re 1 [micro]Pa at 10 m.  re 1 [micro]Pa at 10 m.  1 [micro]Pa at 10 m.
                                      --------------------------------------------------
Source...............................                  Denes et al. 2016                 NMFS 2023.
                                      --------------------------------------------------
Timing per pile......................  20 minutes/pile; 240     20 minutes/pile; 240     20 minutes/pile; 360
                                        strikes/pile.            strikes/pile.            strikes/pile.
Maximum number piles per day.........  6......................  6......................  6.
Maximum number of days of activity...  13.....................  6......................  4.
Distance to below Level B harassment   255 meters.............  255 meters.............  1,000 meters.
 threshold \a\.
Total Level B area (km\2\)...........  0.2038.................  0.2038.................  0.3137.
Level B area (km\2\) within harbor...  0.18...................  0.18...................  0.18.
                                      --------------------------------------------------------------------------
Sea otter density inside harbor......               111.11 sea otters/km\2\
                                      --------------------------------------------------
Potential sea otters affected by       19.9998................  19.9998................  19.9998.
 Level B sound per day within harbor.
Potential sea otters affected by       20.....................  20.....................  20.
 Level B sound per day within harbor
 (rounded).
Potential Level B harassment events    260....................  120....................  80.
 within harbor.
Level B area (km\2\) outside harbor..  0.0238.................  0.0238.................  0.1337.
                                      --------------------------------------------------------------------------
Sea otter density outside harbor.....               21.15 sea otters/km\2\
                                      --------------------------------------------------
Potential sea otters affected by       0.5034.................  0.5034.................  2.8278.
 Level B sound per day outside harbor.
Potential sea otters affected by       1......................  1......................  3.
 Level B sound per day outside harbor
 (rounded).
Potential Level B harassment events    13.....................  6......................  12.
 outside harbor.
Total potential Level B harassment     273....................  126....................  92.
 events.
----------------------------------------------------------------------------------------------------------------


    Table 5--Summary of Sound Level, Timing of Sound Production, Distance From Sound Source to Below Level A
   Harassment and Level B Harassment Thresholds, Days of Impact, Sea Otters in Level A and Level B Harassment
  Ensonification Area, and Total Otters Expected To Be Harassed Through Behavioral Disturbance by Down-the-Hole
                                                  Pile Driving
----------------------------------------------------------------------------------------------------------------
                                            41-cm (16-in)            46-cm (18-in)
              Pile size                     permanent pile           permanent pile      76-cm (30-in) permanent
                                             installation             installation          pile installation
----------------------------------------------------------------------------------------------------------------
Total number of piles................  50.....................  20.....................  16.
                                      --------------------------------------------------
Sound level..........................    159 dB (SEL)/167 dB (RMS) re 1 [mu]Pa at 10 m   164 dB (SEL)/174 dB
                                                                                          (RMS) re 1 [mu]Pa at
                                                                                          10 m.
                                      --------------------------------------------------
Source...............................               Heyvaert and Reyff 2021              Reyff and Heyvaert
                                                                                          2019, Reyff 2020,
                                                                                          Denes et al. 2019.
                                      --------------------------------------------------
Timing per pile......................  75 minutes/pile........  75 minutes/pile........  75 minutes/pile.
Maximum number piles per day.........  4......................  4......................  4.
Maximum number of days of activity...  13.....................  5......................  4.
                                      --------------------------------------------------------------------------
Sea otter density....................                           111.11 sea otters/km\2\
                                      --------------------------------------------------------------------------
Distance to below Level A harassment   35.2 meters............  35.2 meters............  67.1 meters.
 threshold.
Total Level A area (km\2\)...........  0.0039.................  0.0039.................  0.0141.
Level A area (km\2\) after excluding   0.0036.................  0.0036.................  0.0138.
 10-m shutdown zone (0.0003 km\2\).
Potential sea otters affected by       0.4000.................  0.4000.................  1.5333.
 Level A sound per day.
Potential sea otters affected by       1......................  1......................  2.
 Level A sound per day (rounded).
Total potential Level A harassment     13.....................  5......................  8.
 events.
Distance to below Level B harassment   29 meters..............  29 meters..............  86 meters.
 threshold \a\.
Level B area (km\2\).................  0......................  0......................  0.0091.
Potential sea otters affected by       0......................  0......................  1.0111.
 Level B sound per day.
Potential sea otters affected by       0......................  0......................  2.
 Level B sound per day (rounded).

[[Page 76235]]

 
Total potential Level B harassment     0......................  0......................  8.
 events.
----------------------------------------------------------------------------------------------------------------
\a\ Due to differences in how PTS and TTS thresholds are calculated, the Level A isopleths are larger than the
  Level B isopleths.


  Table 6--Summary of Sound Level, Timing of Sound Production, Distance
  From Sound Source to Below Level A Harassment and Level B Harassment
Thresholds, Days of Impact, Sea Otters in Level A and Level B Harassment
  Ensonification Area, and Total Otters Expected To Be Harassed Through
                Behavioral Disturbance by Use of a Skiff
------------------------------------------------------------------------
                Sound source                     Worker transit skiff
------------------------------------------------------------------------
Sound level................................  182 dB (RMS) re 1 [mu]Pa at
                                              0.9 m.
Source.....................................  Kipple and Gabriele 2007.
Number of days of vessel use...............  170.
Sea otter density..........................  111.11 sea otters/km\2\.
Distance to below Level A harassment         0 meters.
 threshold.
Level A area (km\2\).......................  0.
Potential sea otters affected by Level A     0.
 sound per day.
Potential sea otters affected by Level A     0.
 sound per day (rounded).
Total potential Level A harassment events..  0.
Distance to below Level B harassment         26.4 meters.
 threshold.
Total Level B area (km\2\).................  0.007.
Level B area after excluding 10-m shutdown   0.0067.
 zone (0.0003 km\2\).
Potential sea otters affected by Level B     0.7444.
 sound per day.
Potential sea otters affected by Level B     1.
 sound per day (rounded).
Total potential Level B harassment events..  170.
------------------------------------------------------------------------


    Table 7--Summary of Sound Level, Timing of Sound Production, Distance From Sound Source to Below Level B
  Harassment Thresholds, Days of Impact, Sea Otters in Level B Harassment Ensonification Area, and Total Otters
                     Expected To Be Harassed Through Behavioral Disturbance by In-Air Sound
----------------------------------------------------------------------------------------------------------------
                                                      Vibratory pile driving on
                   Sound source                                 shore               Impact pile driving on shore
----------------------------------------------------------------------------------------------------------------
Sound level.......................................  103.2 dB re 20 [mu]Pa at 15 m  101 dB 20 [mu]Pa at 15 m
                                                     (RMS).                         (RMS).
Source............................................  Laughlin 2010................  Ghebreghzabiher 2017.
Maximum number of days of activity................  45...........................  21.
                                                   -------------------------------------------------------------
Sea otter density.................................                    111.11 sea otters/km.\2\
                                                   -------------------------------------------------------------
Distance to below Level B harassment threshold....  22 meters....................  17 meters.
Total Level B area (km\2\)........................  0.0015.......................  0.0009.
Level B area after excluding 10-m shutdown zone     0.0012.......................  0.0006.
 (0.0003 km\2\).
Potential sea otters affected by Level B sound per  0.1333.......................  0.0667.
 day.
Potential sea otters affected by Level B sound per  1............................  1.
 day (rounded).
Total potential Level B harassment events.........  45...........................  21.
----------------------------------------------------------------------------------------------------------------

    Sound levels for all underwater sound sources are unweighted and 
given in dB re 1 [mu]Pa; sound levels for airborne sound sources are 
unweighted and given in dB re 20 [mu]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. Impulsive sound sources are in the 
form of SEL for a single strike.
    To determine the number of sea otters that may experience in-water 
sounds >160 dB re 1[mu]Pa due to pile driving, we multiplied the area 
ensonified to >160 dB re 1[mu]Pa outside Cordova Harbor by the density 
of animals (21.15 sea otters/km\2\) derived from surveys conducted of 
Orca Inlet (Weitzman and Esslinger 2015), whereas the area ensonified 
to >160 dB re 1[mu]Pa within Cordova Harbor was multiplied by the 
density derived from local knowledge (111.11 sea otters/km\2\; 
Greenwood 2022; Prince William Sound Science Center 2022; Schinella 
2022, 2023; Solstice Alaska Consulting Inc. 2022). We applied the same 
methodology to determine the number of sea otters that may experience 
sounds capable of causing PTS. Similarly, to determine the number of 
sea otters that may experience airborne construction sounds >100 dB re 
20 [mu]Pa due to pile driving, we multiplied the area ensonified to 
>100 dB re 20 [mu]Pa by the density of sea otters within the harbor 
(111.11 sea otters/km\2\; Greenwood 2022; Prince William Sound Science 
Center 2022; Schinella 2022, 2023; Solstice Alaska Consulting Inc. 
2022). The number of sea otters expected to be exposed to such sound 
levels can be found in tables 2 through 7. To calculate the underwater 
area ensonified for most types of pile-driving activity, we used 
[pi]r\2\. Given the numerous harbor floats and the number of piles 
being removed and installed, it was not feasible to calculate the 
actual area of water

[[Page 76236]]

ensonified for most activities, so the area of a circle was used for a 
conservative estimate for pile driving activities where the ensonified 
area is entirely within the harbor. Likewise, to calculate the area 
ensonified by pile-driving activities on shore, we used [pi]r\2\. For 
the Level B underwater area ensonified by impact pile driving 76-cm 
(30-in) piles, we used ArcGIS Pro to map the zones and calculate the 
area of the water ensonified, since it is the largest zone and extends 
beyond the harbor. The applicant proposed a universal 10-m (33-ft) 
shutdown zone for all project activities so that area was subtracted 
from all calculated areas when estimating take.
    The area ensonified by the worker transit skiff was estimated by 
multiplying the vessel's anticipated daily track length by twice the 
160 dB radius plus [pi]r\2\ to account for the rounded ends of the 
track line. It was estimated that the distance of each trip would be no 
more than 91.44 m (300 ft).
    We assumed that the different types of 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 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 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.
    In order to minimize exposure of sea otters to sounds above Level A 
harassment thresholds, the applicant will implement shutdown zones 
ranging from 10 to 100 m (33 to 328 ft), based on the pile size and 
type of pile driving or construction activity, 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 City 
of Cordova has requested, and the Service proposes to authorize, small 
numbers of take by Level A harassment during impact pile driving and 
DTH drilling.

Critical Assumptions

    We estimate that 790 takes of 77 sea otters by Level B harassment 
and 30 takes of 5 sea otters by Level A harassment may occur due to the 
City's planned harbor construction activities. In order to conduct this 
analysis and estimate the potential amount of take by 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 significant biological consequences.
    We used the sea otter density for Orca Inlet from surveys and 
analyses conducted by Weitzman and Esslinger (2015) for areas 
ensonified outside Cordova Harbor. Methods and assumptions for these 
surveys can be found in the original publication.
    Multiple local sources (Greenwood 2022; Prince William Sound 
Science Center 2022; Schinella 2022, 2023; Solstice Alaska Consulting 
Inc. 2022) indicated a higher density within the Cordova Harbor--
approximately 20 sea otters at any given time within the 0.18 km\2\ 
area of the harbor, or a density of 111.11 sea otters/km\2\. We used 
this density to estimate take for areas ensonified within the harbor.
    We used sound source verification from recent pile-driving 
activities in a number of 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 underwater 
ensonification zones were based on sound attenuation models using a 
practical spreading loss model; estimation of in-air ensonification 
zones were based on sound attenuation models using a spherical 
spreading loss model. These factors may lead to actual sound values 
differing slightly from those estimated here.
    Finally, the in-water 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 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 Cordova, Alaska, over the course of a year from the date 
of issuance of the IHA. A summary of total estimated take during the 
project, by source, is provided in table 8.

                                Table 8--Total Estimated Takes by Source of Level A and Level B Harassment of Sea Otters
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                    Sea otters      Total takes of       Sea otters      Total takes of
                                                                    Number of    exposed per day     sea otters by    exposed per day     sea otters by
                              Source                                 days of        to Level A          Level A          to Level B          Level B
                                                                     activity       harassment        harassment         harassment        harassment
--------------------------------------------------------------------------------------------------------------------------------------------------------
Vibratory drilling:
    30-to-61-cm (12-in-to-24-in) existing timber pile removal....            6                  0                 0                  1                 6
    30-to-61-cm (12-in-to-24-in) existing steel pile removal.....            3                  0                 0                  1                 3
    61-cm (24-in) template installation..........................           11                  0                 0                  1                11
    61-cm (24-in) template removal...............................            7                  0                 0                  1                 7
    41-cm (16-in) permanent pile installation....................           16                  0                 0                  1                16
    46-cm (18-in) permanent pile installation....................            7                  0                 0                  1                 7
    76-cm (30-in) permanent pile installation....................            5                  0                 0                  1                 5
Impact drilling:
    41-cm (16-in) permanent pile installation....................           13                  0                 0                 21               273
    46-cm (18-in) permanent pile installation....................            6                  0                 0                 21               126
    76-cm (30-in) permanent pile installation....................            4                  1                 4                 23                92
Down-the-hole drilling:
    41-cm (16-in) permanent pile installation....................           13                  1                13                  0                 0
    46-cm (18-in) permanent pile installation....................            5                  1                 5                  0                 0
    76-cm (30-in) permanent pile installation....................            4                  2                 8                  2                 8
Skiff use:
    Worker transit skiff.........................................          170                  0                 0                  1               170

[[Page 76237]]

 
In-air Sound:
    Vibratory pile driving on shore..............................           45                  0                 0                  1                45
    Impact pile driving on shore.................................           21                  0                 0                  1                21
                                                                  --------------------------------------------------------------------------------------
        Totals...................................................          336                  5                30                 77               790
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Over the course of the project, we estimate 790 instances of take 
by Level B harassment of 77 northern sea otters from the Southcentral 
Alaska stock due to behavioral responses of TTS associated with noise 
exposure. 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, and therefore would not rise to the level of an 
injury or Level A harassment.
    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 losses of hearing sensitivity 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. We anticipate that protected 
species observers (PSOs) will be able to reliably detect and prevent 
take by Level A harassment of sea otters up to 10 m (33 ft) away; 
conversely, we anticipate that at distances greater than 10 m, sea 
otters will at times avoid detection. Throughout the project, we 
estimate 30 instances of take by Level A harassment of 5 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, 
startle reactions, or temporary displacement. While mitigation measures 
incorporated into the applicant's request 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 and DTH pile-
driving activities, which have Level A harassment zone radii ranging in 
size from 5.2 to 67.1 m (17 to 220 ft).
    With the adoption of the mitigation measures incorporated in the 
applicant's request and required by this proposed IHA, anticipated take 
was reduced. Those mitigation measures are further described below.

Small Numbers

    To assess whether the authorized incidental taking would be limited 
to ``small numbers'' of marine mammals, the Service 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 the City's specified activities in the specified 
geographic region will result in no more than 790 takes of 77 sea 
otters by Level B harassment and 30 takes of 5 sea otters by Level A 
harassment during the 1-year period of this proposed IHA (see Sum of 
Harassment from All Sources). Take of 82 animals is 0.4 percent of the 
best available estimate of the current Southcentral Alaska stock size 
of 21,617 animals (Esslinger et al. 2021) ((82 / 21,617) x 100 [ap] 
0.4) and represents a ``small number'' of sea otters of that 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 the sea otter 
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 in 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. Each sea otter is 
estimated to be exposed to construction noise for between 3 and 170 
days per year, resulting in repeated exposures.

[[Page 76238]]

However, injuries (i.e., Level A harassment or PTS) due to chronic 
sound exposure are estimated to occur over a longer time scale 
(Southall et al. 2019). The area that will experience noise greater 
than Level B thresholds due to pile driving is small (less than 0.0141 
km\2\), and an animal 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, and the amount of time it may take for 
permanent injury is considerably longer than that of mammals primarily 
under water. 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 result in measurable changes in survival or 
reproduction.
    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 
820 incidental takes of 82 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 the applicant's 
mitigation and monitoring plan. These mitigation measures are designed 
to minimize interactions with and impacts to sea otters. These measures 
and the monitoring and reporting procedures are required for the 
validity of our finding and are a necessary component of the proposed 
IHA. 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.

Least Practicable Adverse Impacts

    We find that the mitigation measures required by this proposed IHA 
will affect the least practicable adverse impacts on the 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 manner and 
degree to which the successful implementation of the measures are 
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). We assessed whether any additional 
practicable requirements could be implemented to further reduce 
effects, but did not identify any.
    To reduce the potential for disturbance from acoustic stimuli 
associated with the activities, the City of Cordova will implement 
mitigation measures, including the following:
     Using a project design that incorporates the smallest 
diameter piles and footprint practicable while minimizing the overall 
number of piles and area;
     Using a project design that does not include dredging or 
excavating below the high tide line;
     Using a project design that does not include blasting;
     Using pile driving equipment with muffler systems to 
reduce in-air noise generation;
     Using a vibratory hammer equipped with a suppressor to 
reduce rattling;
     Using dampeners to eliminate steel-on-steel in-air noise;
     Employing a sediment curtain during all DTH pile driving 
to contain drill spoils and to minimize turbidity;
     Development of a marine mammal monitoring and mitigation 
plan;
     Establishment of shutdown and monitoring zones;
     Visual mitigation monitoring by designated protected 
species observers (PSO);
     Site clearance before startup;
     Soft-start procedures; and
     Shutdown procedures.
    The Service has not identified any additional (i.e., not already 
incorporated into the applicant's request) mitigation or monitoring 
measures that are practicable and would further reduce potential 
impacts to sea otters and their habitat.

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 
construction activities take place within the Cordova Harbor, where 
firearm use is prohibited. We therefore propose a finding that the 
applicant'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 finding, we considered the 
timing and location of the planned activities and the timing and 
location of subsistence harvest activities in the project area.

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 take is consistent with that anticipated in the 
small numbers, negligible impact, and subsistence use analyses; and to 
detect any unanticipated effects on the species. Monitoring plans 
include steps to document when and how sea otters are encountered and 
their numbers and behaviors during these encounters. This information 
allows the Service 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, duration 
of interaction, and closest approach to the project activity.
    As proposed, monitoring activities will be summarized and reported 
in formal reports. The applicant must 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 expiration of the IHA. We will require an approved plan for 
monitoring and reporting the effects of pile driving and marine 
construction activities on sea otters prior to issuance of an IHA. We 
will require approval of the monitoring results for continued operation 
under the IHA.
    We find that these proposed monitoring and reporting requirements 
to evaluate the potential impacts of planned activities will ensure 
that the effects of the activities remain consistent with the rest of 
the findings.

Required Determinations

National Environmental Policy Act (NEPA)

    We have prepared a draft environmental assessment in accordance 
with the NEPA (42 U.S.C.

[[Page 76239]]

4321 et seq.). We have preliminarily concluded that authorizing the 
nonlethal, incidental, unintentional take by Level B harassment of up 
to 790 takes of 77 sea otters and by Level A harassment of up to 30 
takes of 5 sea otters from the Southcentral Alaska stock in the 
specified geographic region during the specified activities during the 
regulatory period 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.

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 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 
Service has determined that, due to this project's locations and 
activities, the Tribal organizations and communities near Cordova, 
Alaska, as well as relevant Alaska Native Claims Settlement Act 
corporations, will not be impacted by this project. Regardless, we will 
be reaching out to them 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.

Proposed Authorization

    We propose to authorize the nonlethal incidental take by Level A 
and Level B harassment of 820 takes of 82 sea otters from the 
Southcentral Alaska stock. Authorized take may be caused by pile 
driving and marine construction activities conducted by the City of 
Cordova in Cordova, Alaska, over the course of a year from the date of 
issuance of the IHA. We do not anticipate or authorize any lethal take 
to sea otters resulting from these activities.

A. General Conditions for the Incidental Harassment Authorization (IHA)

    (1) Activities must be conducted in the manner described in the 
request from the City of Cordova 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 
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., greater 
than 820 takes of 82 of the Southcentral Alaska stock of northern sea 
otters, a form of take other than Level A or Level B harassment, or 
take of one or more sea otters through methods not described in the 
IHA), the City of Cordova 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 Service within 48 
hours; and
    (iii) suspend further activities until the Service 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 
conditions of the IHA 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 the City of Cordova's 
request. Changes to the specified project without prior authorization 
may invalidate the IHA.
    (5) The City of Cordova's request is approved and fully 
incorporated into this IHA unless exceptions are specifically noted 
herein. The request includes:
    (i) The City of Cordova's original request for an IHA, dated 
February 28, 2023;
    (ii) Revised requests, dated April 27, May 18, and June 8, 2023;
    (iii) Marine Mammal Mitigation and Monitoring Plan; and
    (iv) Google Earth package;
    (6) Operators will allow Service personnel or the Service'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 the City of Cordova's 
authority, including all contractors and subcontractors.

B. Avoidance and Minimization

    (7) 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.
    (8) 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.
    (9) 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.
    (10) 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.
    (11) All in-water work along the shoreline must be conducted during 
low tide when the site is dewatered to the maximum extent practicable.

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:
    (12) Vessels must remain at least 500 m (0.3 mi) from rafts of sea 
otters, unless

[[Page 76240]]

safety is a factor. Vessels must reduce speed and maintain a distance 
of 100 m (328 ft) from all sea otters, unless safety is a factor.
    (13) 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 (66 ft)) whenever 
practicable.
    (14) When weather conditions require, such as when visibility 
drops, vessels must adjust speed accordingly to avoid the likelihood of 
injury to sea otters.
    (15) Vessel operators must be provided written guidance for 
avoiding collisions and minimizing disturbances to sea otters. Guidance 
will include measures identified in paragraphs (C)(12) through (15) of 
this section.

D. Monitoring

    (16) Operators shall work with protected species observers (PSO) 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.
    (17) 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.
    (18) 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.
    (19) 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 Service to review.
    (20) 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.
    (21) 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 duration of the encounter, and the distance at last 
observation in order 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.
    (22) Monitoring of the shutdown zone must continue for 30 minutes 
following completion of pile installation.

E. Measures To Reduce Impacts to Subsistence Users

    (23) Prior to conducting the work, the City of Cordova 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) If any concerns remain, develop a plan of cooperation in 
consultation with the Service and subsistence stakeholders to address 
these concerns.

F. Reporting Requirements

    (24) The City of Cordova must notify the Service at least 48 hours 
prior to commencement of activities.
    (25) Monthly reports will be submitted to the Service'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.
    (26) A final report will be submitted to the Service's MMM within 
90 days after completion of work or expiration of the IHA. The report 
will include:
    (i) A summary of monitoring efforts (hours of monitoring, 
activities monitored, number of PSOs, and, if requested by the Service, 
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 greater than or equal to 160 dB 
(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 Service in the form of electronic database or spreadsheet files.
    (27) 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 Service within 24 hours of the discovery to either the 
Service's MMM (1-800-362-5148, business hours), 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 Service.
    (28) All reports shall be submitted by email to 
[email protected].
    (29) The City of Cordova must notify the Service upon project 
completion or end of the work season.

Request for Public Comments

    If you wish to comment on this proposed authorization, the 
associated

[[Page 76241]]

draft environmental assessment, or both documents, you may submit your 
comments by either of the methods described in ADDRESSES. Please 
identify whether you are commenting on the proposed authorization, 
draft environmental assessment, or both, 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 Service will consider all 
comments that are received before the close of the comment period (see 
DATES). The Service 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 Fisheries and Ecological Services, Alaska 
Region.
[FR Doc. 2023-24428 Filed 11-3-23; 8:45 am]
BILLING CODE 4333-15-P