[Federal Register Volume 90, Number 42 (Wednesday, March 5, 2025)]
[Notices]
[Pages 11282-11302]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2025-03543]
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DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
[RTID 0648-XE543]
Takes of Marine Mammals Incidental to Specified Activities;
Taking Marine Mammals Incidental to Small Boat Harbor Preconstruction
Activities (Geotechnical Surveys) in St. George, Alaska
AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and
Atmospheric Administration (NOAA), Commerce.
ACTION: Notice; proposed incidental harassment authorization; request
for comments on proposed authorization and possible renewal.
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SUMMARY: NMFS has received a request from the United States Army Corps
of Engineers (USACE) for authorization to take marine mammals
incidental to geotechnical drilling in St. George, Alaska. Pursuant to
the Marine Mammal Protection Act (MMPA), NMFS is requesting comments on
its proposal to issue an incidental harassment authorization (IHA) to
incidentally take marine mammals during the specified activities. NMFS
is also requesting comments on a possible one-time, 1-year renewal that
could be issued under certain circumstances and if all requirements are
met, as described in Request for Public Comments at the end of this
notice. NMFS will consider public comments prior to making any final
decision on the issuance of the requested MMPA authorization and agency
responses will be summarized in the final notice of our decision.
DATES: Comments and information must be received no later than April 4,
2025.
ADDRESSES: Comments should be addressed to Jolie Harrison, Chief,
Permits and Conservation Division, Office of Protected Resources,
National Marine Fisheries Service and should be submitted via email to
ITP.Fleming@noaa.gov. Electronic copies of the application and
supporting documents, as well as a list of the references cited in this
document, may be obtained online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities. In case of problems accessing these documents,
please call the contact listed below.
Instructions: NMFS is not responsible for comments sent by any
other method, to any other address or individual, or received after the
end of the comment period. Comments, including all attachments, must
not exceed a 25-megabyte file size. All comments received are a part of
the public record and will generally be posted online at https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act without change. All personal identifying
information (e.g., name, address) voluntarily submitted by the
commenter may be publicly accessible. Do not submit confidential
business information or otherwise sensitive or protected information.
FOR FURTHER INFORMATION CONTACT: Kate Fleming, Office of Protected
Resources, NMFS, (301) 427-8401.
SUPPLEMENTARY INFORMATION:
Background
The MMPA prohibits the ``take'' of marine mammals, with certain
exceptions. Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361
et seq.) direct the Secretary of Commerce (as delegated to NMFS) to
allow, upon request, the incidental, but not intentional, taking of
small numbers of marine mammals by U.S. citizens who engage in a
specified activity (other than commercial fishing) within a specified
geographical region if certain findings are made and either regulations
are proposed or, if the taking is limited to harassment, a notice of a
proposed IHA is provided to the public for review.
Authorization for incidental takings shall be granted if NMFS finds
that the taking will have a negligible impact on the species or
stock(s) and will not have an unmitigable adverse impact on the
availability of the species or stock(s) for taking for subsistence uses
(where relevant). Further, NMFS must prescribe the permissible methods
of taking and other ``means of effecting the least practicable adverse
impact'' on the affected species or stocks and their habitat, paying
particular attention to rookeries, mating grounds, and areas of similar
significance, and on the availability of the species or stocks for
taking for certain subsistence uses (referred to in shorthand as
``mitigation''); and requirements pertaining to the monitoring and
reporting of the takings. The definitions of all applicable MMPA
statutory terms used above are included in the relevant sections below
and can be found in section 3 of the MMPA (16 U.S.C. 1362) and NMFS
regulations at 50 CFR 216.103.
National Environmental Policy Act
To comply with the National Environmental Policy Act of 1969 (NEPA;
42 U.S.C. 4321 et seq.) and NOAA Administrative Order (NAO) 216-6A,
NMFS must review our proposed action (i.e., the issuance of an IHA)
with respect to potential impacts on the human environment.
This action is consistent with categories of activities identified
in Categorical Exclusion B4 (IHAs with no anticipated serious injury or
mortality) of the Companion Manual for NAO 216-6A, which do not
individually or cumulatively have the potential for significant impacts
on the quality of the human environment and for which we have not
identified any extraordinary circumstances that would preclude this
categorical exclusion. Accordingly, NMFS has preliminarily determined
that the issuance of the proposed IHA qualifies to be categorically
excluded from further NEPA review.
Summary of Request
On October 30, 2024, NMFS received a request from USACE for an IHA
to take marine mammals incidental to geotechnical surveys to be
conducted as part of preconstruction activities associated with a new
small boat harbor in St. George, Alaska. Following NMFS' review of the
application, and discussions between NMFS and USACE, the application
was deemed adequate and complete on January 29, 2025. The USACE
submitted a final revised version on February 19, 2025. The USACE's
request is for take of northern fur seal, by Level A and Level B
harassment and, of harbor seal, by Level B harassment only. Neither
USACE nor NMFS expect serious injury or mortality
[[Page 11283]]
to result from this activity and, therefore, an IHA is appropriate.
This proposed IHA would cover 1 year of preconstruction activity
associated with a larger project involving construction of a new small
boat harbor.
Description of Proposed Activity
Overview
The USACE is in the preconstruction, engineering, and design (PED)
phase for constructing a small boat harbor in St. George, Alaska.
Between April 15, 2025 and June 15, 2025, USACE would conduct Large
Penetration Testing (LPT) and borehole drilling. These methods would
introduce underwater sounds that may result in take, by Level A and
Level B harassment, of marine mammals.
Dates and Duration
The proposed IHA would be effective from April 15, 2025 to June 15,
2025, reflecting a proposed seasonal work window designed to minimize
effects on northern fur seal reproductive behavior. See Proposed
Mitigation for further detail. The project would require approximately
15 days of geotechnical drilling. In-water construction activities
would occur during daylight hours only, between a 14 to 18 hour daily
work window.
Specific Geographic Region
St. George is on St. George Island, the southernmost and second
largest group of five inactive volcanic islands that compose the
Pribilof Archipelago located in the southern Bering Sea, approximately
760 miles [(mi.), (1,223 kilometers, (km)] west of Anchorage, Alaska
and 220 mi. (354 km) north-northwest of Unalaska Island. St. George
Island's position at the western margin of Alaska's continental shelf
puts it in close proximity to much deeper waters of the Bering Sea's
abyssal plain. The abrupt change in seafloor elevation occurring at the
continental slope facilitates natural upwelling processes; as a result,
surface waters in the region are extremely productive.
The project site is adjacent to St. George, on the north side of
St. George Island, and spans the embayment between the Old Jetty
(eastern side of the project area) east across to North Rookery
(western side of the project area), which is the largest northern fur
seal rookery in the world (Williams, 2024 personal communication) (see
figure 2). Water depths at borehole locations range from approximately
3 feet [(ft.) (0.9 meters (m)] deep nearshore to approximately 20 ft.
deep (6.1 m) near the entrance channel. The site experiences strong
northerly winds and swell. Fog is highly variable but can persist for
days or weeks, though USACE indicates that fog is most consistent in
July and August.
BILLING CODE 3510-22-P
[GRAPHIC] [TIFF OMITTED] TN05MR25.000
[[Page 11284]]
BILLING CODE 3510-22-C
Detailed Description of the Specified Activity
USACE plans to conduct geotechnical surveys in the embayment
between the Old Jetty west to North Rookery, to inform preconstruction,
engineering, and design for construction of a small boat harbor on St.
George Island, Alaska. Activities to be completed during the period of
the proposed IHA include geotechnical sampling at 15 borehole sites
within the harbor footprint (figure 1-2 in application). Two additional
sites would be sampled on land to the east of the in-water footprint.
The geotechnical sampling would involve two components: (1) LPT, using
a 2.5 in (6.4 centimeter) (inside diameter) to 3.0-inch (7.6
centimeter) (outside diameter) split barrel sampler, and impact hammer
weighing 340 pounds (154 kilograms) falling 30 inches (76.2
centimeters), and (2) borehole drilling from a barge that will be
positioned by a tugboat and held in position with a 4-point anchoring
system or spuds.
The LPT is an impulsive sampling method, in which the sample tube
is hammered into the ground at the bottom of the borehole. For all
holes, LPT split barrel or grab samples would be obtained at the
surface (a split barrel is a casing that can be split in half at the
surface so that the soil can be examined), followed by LPT drive
samples at 2.5 ft. (0.76 m), 5 ft. (1.5 m), 7.5 ft. (2.3 m), and 10 ft.
(3 m) and at intervals of 5 ft. (1.5 m) to refusal depth (typically
when bedrock is encountered). The number of blows needed for the tube
to penetrate a fixed depth relates to the hardness of the ground.
Upon refusal, LPT equipment would be removed and borehole drilling,
in which a drill rod lowered inside casings and driven by a motor to
rotate advance along the substrate, would continue in the same hole
that was created by LTP and the drill bit would be used to obtain rock
core samples. USACE assumes that bedrock would be encountered 0-15 ft.
below ground surface in all boreholes. Rock core samples would be
obtained to the borehole termination depth indicated in figure 1-2 in
USACE's application.
USACE estimates that one hole will be completed each day, with the
boring component taking 10 hours and the LPT component taking 1 hour
(table 1).
Table 1--Summary of Planned Activities
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Strikes or
Activity type Total holes Holes/day Duration per Strikes per minutes per
hole (min) hole day
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Borehole drilling............... 15 1 540 N/A 540
LPT............................. 60 3,600 3,600
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Proposed mitigation, monitoring, and reporting measures are
described in detail later in this document (please see Proposed
Mitigation and Proposed Monitoring and Reporting).
Description of Marine Mammals in the Area of Specified Activities
Sections 3 and 4 of the application summarize available information
regarding status and trends, distribution and habitat preferences, and
behavior and life history of the potentially affected species. NMFS
fully considered all of this information, and we refer the reader to
these descriptions, instead of reprinting the information. Additional
information regarding population trends and threats may be found in
NMFS' Stock Assessment Reports (SARs; https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments) and
more general information about these species (e.g., physical and
behavioral descriptions) may be found on NMFS' website (https://www.fisheries.noaa.gov/find-species).
Table 2 lists all species or stocks for which take is expected and
proposed to be authorized for this activity and summarizes information
related to the population or stock, including regulatory status under
the MMPA and Endangered Species Act (ESA) and potential biological
removal (PBR), where known. PBR is defined by the MMPA as the maximum
number of animals, not including natural mortalities, that may be
removed from a marine mammal stock while allowing that stock to reach
or maintain its optimum sustainable population (as described in NMFS'
SARs). While no serious injury or mortality is anticipated or proposed
to be authorized here, PBR and annual serious injury and mortality (M/
SI) from anthropogenic sources are included here as gross indicators of
the status of the species or stocks and other threats.
Marine mammal abundance estimates presented in this document
represent the total number of individuals that make up a given stock or
the total number estimated within a particular study or survey area.
NMFS' stock abundance estimates for most species represent the total
estimate of individuals within the geographic area, if known, that
comprises that stock. For some species, this geographic area may extend
beyond U.S. waters. All managed stocks in this region are assessed in
NMFS' U.S. Alaska SARs. All values presented in table 2 are the most
recent available at the time of publication and are available online
at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments.
Table 2--Species \1\ That May Be Impacted by the Specified Activities
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ESA/ MMPA status/ Stock abundance (CV,
Common name Scientific name Stock strategic (Y/N) Nmin, most recent PBR Annual M/
\2\ abundance survey) \3\ S \4\
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Order--Odontoceti (toothed whales, dolphins, and porpoises)
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Family Delphinidae:
Killer whale.................... Orcinus orca........... Eastern North Pacific -, -, N 1920 (N/A, 1,920, 19 1.3
Alaska Resident. 2019) \5\.
[[Page 11285]]
Eastern North Pacific -, -, N 587 (N/A, 587, 2012) 5.9 0.8
Gulf of Alaska, \5\.
Aleutian Islands and
Bering Sea Transient.
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Order Carnivora--Pinnipedia
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Family Otariidae (eared and sea
lions):
Northern fur seal............... Callorhinus ursinus.... Eastern Pacific........ -, D, Y 626,618 (0.2, 530,376, 11,403 373
2019) \6\.
Steller sea lion................ Eumetopias jubatus..... Western................ E, D, Y 49,837 (N/A, 49,837, 299 267
2022) \7\.
Family Phocidae (earless seals):
Harbor seal..................... Phoca vitulina......... Pribilof Islands....... -, -, N 229 (N/A, 229, 2018) 7 0
\8\.
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\1\ Information on the classification of marine mammal species can be found on the web page for The Society for Marine Mammalogy's Committee on
Taxonomy; [https://marinemammalscience.org/science-and-publications/list-marine-mammal-species-subspecies)].
\2\ Endangered Species Act (ESA) status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-) indicates that the species is not listed
under the ESA or designated as depleted under the MMPA. Under the MMPA, a strategic stock is one for which the level of direct human-caused mortality
exceeds PBR or which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed
under the ESA is automatically designated under the MMPA as depleted and as a strategic stock.
\3\ NMFS marine mammal stock assessment reports online at https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports-region. CV is coefficient of variation; Nmin is the minimum estimate of stock abundance.
\4\ These values, found in NMFS's SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined (e.g.,
commercial fisheries, ship strike). Annual M/SI often cannot be determined precisely and is in some cases presented as a minimum value or range.
\5\ Nest is based upon counts of individuals identified from photo-ID catalogs.
\6\ Survey years = Sea Lion Rock--2014; St. Paul and St. George Is--2014, 2016, 2018; Bogoslof Is.--2015, 2019.
\7\ Nest is best estimate of counts, which have not been corrected for animals at sea during abundance surveys. Estimates provided are for the U.S.
only. The overall Nmin is 73,211 and overall PBR is 439.
\8\ Nest is best estimate of counts, which have not been corrected for animals at sea during abundance surveys.
In addition, the northern sea otter and Pacific walrus may be found
in the Pribilof Islands. However, these species are managed by the U.S.
Fish and Wildlife Service and are not considered further in this
document.
Killer Whale
Both transient and resident killer whales occur in the Pribilof
Island region. While data are limited, the transient ecotype has been
observed and reported in nearshore waters of the Pribilof Islands
preying on pinnipeds, including from vantage points near the project
area in the spring and summer (Robson et al., 2010).
Northern Fur Seal
About half of the world's population of northern fur seals breeds
on the Pribilof Islands (St. George Island, St. Paul Island, and Sea
Lion Rock) (NMFS, 2024). There are six northern fur seal rookeries on
St. George Island. North Rookery, directly adjacent to the western
portion of the project site, represents 28 percent of all northern fur
seals breeding and resting on St. George and is the largest northern
fur seal colony on the island (Williams, 2024 personal communication).
Northern fur seals exhibit strong natal site fidelity, sexual
segregation, and seasonally migrate (Gentry, 1998).
While northern fur seals spend a majority of their days each year
at sea, they will haul out on land during the spring and summer to
breed and molt (NMFS, 2024). Adult males are the first to return from
their seasonal migration, landing and hauling out along the shoreline
as early as April. Adult males will land at a number of sites where
they begin to determine which site to establish their breeding
territory for the arrival of females in mid-June and July. Specifically
at North Rookery, the distribution of adult male breeding territories
has shifted south and east along the shoreline towards the Old Jetty
and dock (Williams, 2024, personal communication). In April and May,
non-breeding aged (i.e., those less than 7 years old) males will land
and haul out along the rocky shoreline adjacent to the Access Ramp
labeled in figure 4-3 in the USACE's application. Depending on the
distribution and density of territories and adult male defensive
behavior the non-breeding males will navigate up the access ramp area
inland or spread south along the narrow shoreline bounded by a cliff
that prevents inland access. Meanwhile, territorial males will occupy
and defend prime breeding territories before females arrive (the green
areas in figure 4-3 in the USACE's application). Pregnant females
arrive around mid-June each year and primarily concentrate in the
yellow shaded areas of figure 4-3 in the USACE's application. They give
birth just days after arrival on land and then mate (NMFS, 2024). In
August, most territorial males will abandon their breeding sites.
Females will begin their winter migration in November. Pups are nursed
until weaning (about 4 months) and leave their breeding site before
their mothers to forage independently for the first time.
While breeding, territorial males fast and do not leave their
territories. Females cycle between land to nurse their pups and sea to
forage, with their foraging bouts at sea increasing as their pup grows
(Gentry, 1998). Non-breeding males are excluded by territorial males
from this terrestrial habitat that is often referred to as the rookery
or breeding area. Thus non-breeding males occupy separate habitat
inland or adjacent on the coast, often called hauling grounds, during
the breeding season, and they cycle between resting on the hauling
grounds and foraging at sea (Sterling and Ream, 2004).
The NMFS Alaska Regional Office estimates that land-based counts of
females represent one-third to one-quarter of the northern fur seals
that utilize the immediate area across a 1-3 week period (Williams,
2024, personal communication). Less information is available regarding
non-breeding males utilizing the site in April and May. Historic counts
of non-breeding males for North Rookery are not available.
USACE estimated 126 to 300 northern fur seals hauled out in the
project site during monitoring events conducted on 5 days in April and
June, 2024 (see
[[Page 11286]]
Appendix B in the USACE's application).
Steller Sea Lion
Steller sea lions are year-round residents of the Pribilof Islands
with critical habitat identified at Walrus Island (NMFS, 2008). The
spring-time occurrence of Steller sea lions on St. George Island near
the project area is highly variable across years, with consistently
occupied non-breeding hauling grounds at East Reef Rookery, Dalnoi
Point and Tolstoi Points. Steller sea lions may also be found
intermittently resting at North and South Rookery or in the water
transiting among resting sites at times intermixed with northern fur
seals (Williams 2024, personal communication). Typically there are no
Steller sea lions present on land adjacent to the bay where the project
is to occur in the spring, but occasionally they haul out at sites
across North Rookery (primarily the western end, but extending east
towards the work site), East Reef rookery, and East Cliffs rookery in
groups of up to 100 (Williams 2024, personal communication). When
present, they tend to travel through the project area and do not
linger. During monitoring events conducted on 5 days in April and June
2024, USACE observed 3 to 14 Steller sea lions traveling near the
western portion of the project area each survey day.
Harbor Seal
Harbor seals inhabit the Pribilof Island region year-round in far
smaller numbers than northern fur seal. The Pribilof Islands stock of
harbor seals inhabit all of the Pribilof Islands with the highest
numbers found on Otter Island followed by St. George Island (Muto et
al., 2019). Harbor seals occur to the west of the project area on the
north shore of St. George Island at a site named Needlerock (Williams,
2024, personal communication). Additionally, USACE reports that local
residents of St. George indicate that it is uncommon to observe harbor
seals in the area of Harbor Cove (see application). However, between
three and eight harbor seals were observed near the Old Jetty on 3 days
in April, 2024, during USACE's monitoring events. No harbor seals were
observed on land or in the water during monitoring events conducted on
2 days in June, 2024.
Marine Mammal Hearing
Hearing is the most important sensory modality for marine mammals
underwater, and exposure to anthropogenic sound can have deleterious
effects. To appropriately assess the potential effects of exposure to
sound, it is necessary to understand the frequency ranges marine
mammals are able to hear. Not all marine mammal species have equal
hearing capabilities (e.g., Richardson et al., 1995; Wartzok and
Ketten, 1999; Au and Hastings, 2008). To reflect this, Southall et al.
(2007, 2019) recommended that marine mammals be divided into hearing
groups based on directly measured (behavioral or auditory evoked
potential techniques) or estimated hearing ranges (behavioral response
data, anatomical modeling, etc.). Generalized hearing ranges were
chosen based on the ~65 decibel (dB) threshold from composite
audiograms, previous analyses in NMFS (2018), and/or data from Southall
et al. (2007) and Southall et al. (2019). We note that the names of two
hearing groups and the generalized hearing ranges of all marine mammal
hearing groups have been recently updated (NMFS 2024) as reflected
below in table 3.
Table 3--Marine Mammal Hearing Groups
[NMFS, 2024]
------------------------------------------------------------------------
Hearing group Generalized hearing range *
------------------------------------------------------------------------
Low-frequency (LF) cetaceans (baleen 7 Hz to 36 kHz.
whales).
High-frequency (HF) cetaceans 150 Hz to 160 kHz.
(dolphins, toothed whales, beaked
whales, bottlenose whales).
Very High-frequency (VHF) cetaceans 200 Hz to 165 kHz.
(true porpoises, Kogia, river
dolphins, Cephalorhynchid,
Lagenorhynchus cruciger & L.
australis).
Phocid pinnipeds (PW) (underwater) 40 Hz to 90 kHz.
(true seals).
Otariid pinnipeds (OW) (underwater) 60 Hz to 68 kHz.
(sea lions and fur seals).
------------------------------------------------------------------------
* Represents the generalized hearing range for the entire group as a
composite (i.e., all species within the group), where individual
species' hearing ranges may not be as broad. Generalized hearing range
chosen based on ~65 dB threshold from composite audiogram, previous
analysis in NMFS 2018, and/or data from Southall et al. 2007; Southall
et al. 2019. Additionally, animals are able to detect very loud sounds
above and below that ``generalized'' hearing range.
For more detail concerning these groups and associated frequency
ranges, please see NMFS (2024) for a review of available information.
Potential Effects of Specified Activities on Marine Mammals and Their
Habitat
This section provides a discussion of the ways in which components
of the specified activity may impact marine mammals and their habitat.
The Estimated Take of Marine Mammals section later in this document
includes a quantitative analysis of the number of individuals that are
expected to be taken by this activity. The Negligible Impact Analysis
and Determination section considers the content of this section, the
Estimated Take of Marine Mammals section, and the Proposed Mitigation
section, to draw conclusions regarding the likely impacts of these
activities on the reproductive success or survivorship of individuals
and whether those impacts are reasonably expected to, or reasonably
likely to, adversely affect the species or stock through effects on
annual rates of recruitment or survival.
Description of Sound Sources
The marine soundscape is comprised of both ambient and
anthropogenic sounds. Ambient sound is defined as the all-encompassing
sound in a given place and is usually a composite of sound from many
sources both near and far [American National Standards Institute
(ANSI), 1995]. The sound level of an area is defined by the total
acoustical energy being generated by known and unknown sources. These
sources may include physical (e.g., waves, wind, precipitation,
earthquakes, ice, atmospheric sound), biological (e.g., sounds produced
by marine mammals, fish, and invertebrates), and anthropogenic sound
(e.g., vessels, dredging, aircraft, construction).
The sum of the various natural and anthropogenic sound sources at
any given location and time--which comprise ``ambient'' or
``background'' sound--depends not only on the source levels (as
determined by current
[[Page 11287]]
weather conditions and levels of biological and shipping activity) but
also on the ability of sound to propagate through the environment. In
turn, sound propagation is dependent on the spatially and temporally
varying properties of the water column and sea floor, and is frequency-
dependent. As a result of the dependence on a large number of varying
factors, ambient sound levels can be expected to vary widely over both
coarse and fine spatial and temporal scales. Sound levels at a given
frequency and location can vary by 10-20 dB from day to day (Richardson
et al., 1995). The result is that, depending on the source type and its
intensity, sound from the specified activity may be a negligible
addition to the local environment or could form a distinctive signal
that may affect marine mammals.
In-water activities associated with this project would include use
of geotechnical survey techniques (LPT and borehole drilling). The
sounds produced by these activities fall into one of two general sound
types: impulsive and non-impulsive. Impulsive sound (e.g., explosions,
gunshots, sonic booms, impact pile driving, LPT) produce signals that
are brief (typically considered to be less than 1 second), broadband,
atonal transients (ANSI, 1986; National Institute for Occupational
Safety and Health (NIOSH), 1998; International Organization for
Standardization (ISO), 2003; ANSI, 2005) and occur either as isolated
events or repeated in some succession. Impulsive sounds are all
characterized by a relatively rapid rise from ambient pressure to a
maximal pressure value followed by a rapid decay period that may
include a period of diminishing, oscillating maximal and minimal
pressures, and generally have an increased capacity to induce physical
injury as compared with sounds that lack these features.
Non-impulsive sounds can be tonal, narrowband, or broadband, brief
or prolonged, and may be either continuous or non-continuous (ANSI,
1995; NIOSH, 1998). Some of these non-impulsive sounds can be transient
signals of short duration but without the essential properties of
impulses (e.g., rapid rise time). Examples of non-impulsive sounds
include those produced by vessels, aircraft, machinery operations such
as borehole drilling or dredging, vibratory pile driving, and active
sonar systems. The duration of such sounds, as received at a distance,
can be greatly extended in a highly reverberant environment.
LPT is an impulsive sound source, similar to impact pile driving.
Sound generated by impact hammers is characterized by rapid rise times
and high peak levels, a potentially injurious combination (Hastings and
Popper, 2005). Borehole drilling is a continuous non-impulsive sound
source similar to vibratory pile driving. Non-impulsive sounds are
typically characterized by slow rise times and often lower source
levels, which reduces the probability and severity of injury, and sound
energy is distributed over a greater amount of time (Nedwell and
Edwards, 2002; Carlson et al., 2005).
The likely or possible impacts of USACE's proposed activity on
marine mammals could involve both non-acoustic and acoustic stressors.
Potential non-acoustic stressors could result from the physical
presence of equipment and personnel; however, any impacts to marine
mammals are expected to be primarily acoustic in nature. Acoustic
stressors include effects of heavy equipment operation during
geotechnical surveys.
Acoustic Effects
The introduction of anthropogenic noise into the aquatic
environment from geotechnical surveys is the means by which marine
mammals may be harassed from USACE's specified activity. In general,
animals exposed to natural or anthropogenic sound may experience
behavioral, physiological, and/or physical effects, ranging in
magnitude from none to severe (Southall et al., 2007, 2019). In
general, exposure to impact hammering and drilling noise has the
potential to result in behavioral reactions (e.g., avoidance, temporary
cessation of foraging and vocalizing, changes in dive behavior) and, in
limited cases, an auditory threshold shift (TS). Exposure to
anthropogenic noise can also lead to non-observable physiological
responses such an increase in stress hormones. Additional noise in a
marine mammal's habitat can mask acoustic cues used by marine mammals
to carry out daily functions such as communication and predator and
prey detection. The effects of geotechnical surveys on marine mammals
are dependent on several factors, including, but not limited to, sound
type (e.g., impulsive vs. non-impulsive), the species, age and sex
class (e.g., adult male vs. mom with calf), duration of exposure, the
distance between the sampling site and the animal, received levels,
behavior at time of exposure, and previous history with exposure
(Wartzok et al., 2004; Southall et al., 2007). Here, we discuss
physical auditory effects (TSs) followed by behavioral effects and
potential impacts on habitat.
NMFS defines a noise-induced TS as a change, usually an increase,
in the threshold of audibility at a specified frequency or portion of
an individual's hearing range above a previously established reference
level (NMFS, 2018, 2024). The amount of TS is customarily expressed in
dB. A TS can be permanent or temporary. As described in NMFS (2018,
2024), there are numerous factors to consider when examining the
consequence of TS, including, but not limited to, the signal temporal
pattern (e.g., impulsive or non-impulsive), likelihood an individual
would be exposed for a long enough duration or to a high enough level
to induce a TS, the magnitude of the TS, time to recovery (seconds to
minutes or hours to days), the frequency range of the exposure (i.e.,
spectral content), the hearing and vocalization frequency range of the
exposed species relative to the signal's frequency spectrum (i.e., how
animal uses sound within the frequency band of the signal; e.g.,
Kastelein et al., 2014), and the overlap between the animal and the
source (e.g., spatial, temporal, and spectral).
Auditory Injury and Permanent Threshold Shift (PTS)--NMFS defines
auditory injury as ``damage to the inner ear that can result in
destruction of tissue . . . which may or may not result in PTS'' (NMFS,
2024). NMFS defines PTS as a permanent, irreversible increase in the
threshold of audibility at a specified frequency or portion of an
individual's hearing range above a previously established reference
level (NMFS, 2024). Available data from humans and other terrestrial
mammals indicate that a 40-dB TS approximates PTS onset (Ward et al.,
1958, 1959; Ward, 1960; Kryter et al., 1966; Miller, 1974; Ahroon et
al., 1996; Henderson et al., 2008). PTS levels for marine mammals are
estimates, as with the exception of a single study unintentionally
inducing PTS in a harbor seal (Kastak et al., 2008), there are no
empirical data measuring PTS in marine mammals largely due to the fact
that, for various ethical reasons, experiments involving anthropogenic
noise exposure at levels inducing PTS are not typically pursued or
authorized (NMFS, 2018).
Temporary Threshold Shift (TTS)--A temporary, reversible increase
in the threshold of audibility at a specified frequency or portion of
an individual's hearing range above a previously established reference
level (NMFS, 2018). Based on data from cetacean TTS measurements
(Southall et al., 2007, 2019), a TTS of 6 dB is considered the minimum
TS clearly larger than any day-to-day or session-to-session
[[Page 11288]]
variation in a subject's normal hearing ability (Schlundt et al., 2000;
Finneran et al., 2000, 2002). As described in Finneran (2015), marine
mammal studies have shown the amount of TTS increases with cumulative
sound exposure level (SELcum) in an accelerating fashion: At
low exposures with lower SELcum, the amount of TTS is
typically small and the growth curves have shallow slopes. At exposures
with higher SELcum, the growth curves become steeper and
approach linear relationships with the noise SEL.
Depending on the degree (elevation of threshold in dB), duration
(i.e., recovery time), and frequency range of TTS, and the context in
which it is experienced, TTS can have effects on marine mammals ranging
from discountable to serious (similar to those discussed in Auditory
Masking, below). For example, a marine mammal may be able to readily
compensate for a brief, relatively small amount of TTS in a non-
critical frequency range that takes place during a time when the animal
is traveling through the open ocean, where ambient noise is lower and
there are not as many competing sounds present. Alternatively, a larger
amount and longer duration of TTS sustained during time when
communication is critical for successful mother/calf interactions could
have more serious impacts. We note that reduced hearing sensitivity as
a simple function of aging has been observed in marine mammals, as well
as humans and other taxa (Southall et al., 2007), so we can infer that
strategies exist for coping with this condition to some degree, though
likely not without cost.
Many studies have examined noise-induced hearing loss in marine
mammals (see Finneran (2015) and Southall et al. (2019) for summaries).
TTS is the mildest form of hearing impairment that can occur during
exposure to sound (Kryter, 2013). While experiencing TTS, the hearing
threshold rises, and a sound must be at a higher level in order to be
heard. In terrestrial and marine mammals, TTS can last from minutes or
hours to days (in cases of strong TTS). In many cases, hearing
sensitivity recovers rapidly after exposure to the sound ends. For
cetaceans, published data on the onset of TTS are limited to captive
bottlenose dolphin (Tursiops truncatus), beluga whale, harbor porpoise,
and Yangtze finless porpoise (Neophocoena asiaeorientalis) (Southall et
al., 2019). For pinnipeds in water, measurements of TTS are limited to
harbor seals, elephant seals (Mirounga angustirostris), bearded seals
(Erignathus barbatus) and California sea lions (Zalophus californianus)
(Kastak et al., 2007; Kastelein et al., 2019b, 2019c, 2021, 2022a,
2022b; Reichmuth et al., 2019; Sills et al., 2020). TTS was not
observed in spotted (Phoca largha) and ringed (Pusa hispida) seals
exposed to single airgun impulse sounds at levels matching previous
predictions of TTS onset (Reichmuth et al., 2016). These studies
examine hearing thresholds measured in marine mammals before and after
exposure to intense or long-duration sound exposures. The difference
between the pre-exposure and post-exposure thresholds can be used to
determine the amount of threshold shift at various post-exposure times.
The amount and onset of TTS depends on the exposure frequency.
Sounds at low frequencies, well below the region of best sensitivity
for a species or hearing group, are less hazardous than those at higher
frequencies, near the region of best sensitivity (Finneran and
Schlundt, 2013). At low frequencies, onset-TTS exposure levels are
higher compared to those in the region of best sensitivity (i.e., a low
frequency noise would need to be louder to cause TTS onset when TTS
exposure level is higher), as shown for harbor porpoises and harbor
seals (Kastelein et al., 2019a, 2019c). Note that in general, harbor
seals and harbor porpoises have a lower TTS onset than other measured
pinniped or cetacean species (Finneran, 2015). In addition, TTS can
accumulate across multiple exposures, but the resulting TTS will be
less than the TTS from a single, continuous exposure with the same
sound exposure level (SEL) (Mooney et al., 2009; Finneran et al., 2010;
Kastelein et al., 2014, 2015). This means that TTS predictions based on
the total, cumulative SEL will overestimate the amount of TTS from
intermittent exposures, such as sonars and impulsive sources.
Nachtigall et al. (2018) describe measurements of hearing sensitivity
of multiple odontocete species (bottlenose dolphin, harbor porpoise,
beluga, and false killer whale (Pseudorca crassidens)) when a
relatively loud sound was preceded by a warning sound. These captive
animals were shown to reduce hearing sensitivity when warned of an
impending intense sound. Based on these experimental observations of
captive animals, the authors suggest that wild animals may dampen their
hearing during prolonged exposures or if conditioned to anticipate
intense sounds. Another study showed that echolocating animals
(including odontocetes) might have anatomical specializations that
might allow for conditioned hearing reduction and filtering of low-
frequency ambient noise, including increased stiffness and control of
middle ear structures and placement of inner ear structures (Ketten et
al., 2021). Data available on noise-induced hearing loss for mysticetes
are currently lacking (NMFS, 2018). Additionally, the existing marine
mammal TTS data come from a limited number of individuals within these
species.
Relationships between TTS and PTS thresholds have not been studied
in marine mammals, and there is no PTS data for cetaceans, but such
relationships are assumed to be similar to those in humans and other
terrestrial mammals. PTS typically occurs at exposure levels at least
several decibels above that inducing mild TTS (e.g., a 40-dB threshold
shift approximates PTS onset (Kryter et al., 1966; Miller, 1974), while
a 6-dB threshold shift approximates TTS onset (Southall et al., 2007,
2019). Based on data from terrestrial mammals, a precautionary
assumption is that the PTS thresholds for impulsive sounds (such as
impact pile driving pulses as received close to the source) are at
least 6 dB higher than the TTS threshold on a peak-pressure basis and
PTS cumulative sound exposure level thresholds are 15 to 20 dB higher
than TTS cumulative sound exposure level thresholds (Southall et al.,
2007, 2019). Given the higher level of sound or longer exposure
duration necessary to cause PTS as compared with TTS, it is
considerably less likely that PTS could occur.
Activities for this project include LPT and borehole drilling. For
the proposed project, these activities would not occur at the same time
and there would likely be pauses in activities producing the sound
during each day. Given these pauses and the fact that many marine
mammals are likely moving through the project areas and not remaining
for extended periods of time, the potential for TS declines.
Behavioral Harassment--Exposure to noise from borehole drilling and
LPT also has the potential to behaviorally disturb marine mammals.
Generally speaking, NMFS considers a behavioral disturbance that rises
to the level of harassment under the MMPA a non-minor response--in
other words, not every response qualifies as behavioral disturbance,
and for responses that do, those of a higher level, or accrued across a
longer duration, have the potential to affect foraging, reproduction,
or survival. Behavioral disturbance may include a variety of effects,
including subtle changes in behavior (e.g., minor or brief avoidance of
an area or changes
[[Page 11289]]
in vocalizations), more conspicuous changes in similar behavioral
activities, and more sustained and/or potentially severe reactions,
such as displacement from or abandonment of high-quality habitat.
Behavioral responses may include changing durations of surfacing and
dives, changing direction and/or speed; reducing/increasing vocal
activities; changing/cessation of certain behavioral activities (such
as socializing or feeding); eliciting a visible startle response or
aggressive behavior (such as tail/fin slapping or jaw clapping);
avoidance of areas where sound sources are located. Pinnipeds may
increase their haul out time, possibly to avoid in-water disturbance
(Thorson and Reyff, 2006). Behavioral responses to sound are highly
variable and context-specific and any reactions depend on numerous
intrinsic and extrinsic factors (e.g., species, state of maturity,
experience, current activity, reproductive state, auditory sensitivity,
time of day), as well as the interplay between factors (e.g.,
Richardson et al., 1995; Wartzok et al., 2004; Southall et al., 2007,
2019; Weilgart, 2007; Archer et al., 2010). Behavioral reactions can
vary not only among individuals but also within an individual,
depending on previous experience with a sound source, context, and
numerous other factors (Ellison et al., 2012), and can vary depending
on characteristics associated with the sound source (e.g., whether it
is moving or stationary, number of sources, distance from the source).
In general, pinnipeds seem more tolerant of, or at least habituate more
quickly to, potentially disturbing underwater sound than do cetaceans,
and generally seem to be less responsive to exposure to industrial
sound than most cetaceans. Please see appendices B and C of Southall et
al. (2007) and Gomez et al. (2016) for reviews of studies involving
marine mammal behavioral responses to sound.
Habituation can occur when an animal's response to a stimulus wanes
with repeated exposure, usually in the absence of unpleasant associated
events (Wartzok et al., 2004). Animals are most likely to habituate to
sounds that are predictable and unvarying. It is important to note that
habituation is appropriately considered as a ``progressive reduction in
response to stimuli that are perceived as neither aversive nor
beneficial,'' rather than as, more generally, moderation in response to
human disturbance (Bejder et al., 2009). The opposite process is
sensitization, when an unpleasant experience leads to subsequent
responses, often in the form of avoidance, at a lower level of
exposure.
As noted above, behavioral state may affect the type of response.
For example, animals that are resting may show greater behavioral
change in response to disturbing sound levels than animals that are
highly motivated to remain in an area for feeding (Richardson et al.,
1995; Wartzok et al., 2004; National Research Council (NRC), 2005).
Controlled experiments with captive marine mammals have showed
pronounced behavioral reactions, including avoidance of loud sound
sources (Ridgway et al., 1997; Finneran et al., 2003). Observed
responses of wild marine mammals to loud pulsed sound sources (e.g.,
seismic airguns) have been varied but often consist of avoidance
behavior or other behavioral changes (Richardson et al., 1995; Morton
and Symonds, 2002; Nowacek et al., 2007).
Available studies show wide variation in response to underwater
sound; therefore, it is difficult to predict specifically how any given
sound in a particular instance might affect marine mammals perceiving
the signal. If a marine mammal does react briefly to an underwater
sound by changing its behavior or moving a small distance, the impacts
of the change are unlikely to be significant to the individual, let
alone the stock or population. However, if a sound source displaces
marine mammals from an important feeding or breeding area for a
prolonged period, impacts on individuals and populations could be
significant (e.g., Lusseau and Bejder, 2007; Weilgart, 2007; NRC,
2005). However, there are broad categories of potential response, which
we describe in greater detail here, that include alteration of dive
behavior, alteration of foraging behavior, effects to breathing,
interference with or alteration of vocalization, avoidance, and flight.
Changes in dive behavior can vary widely and may consist of
increased or decreased dive times and surface intervals as well as
changes in the rates of ascent and descent during a dive (e.g., Frankel
and Clark, 2000; Costa et al., 2003; Ng and Leung, 2003; Nowacek et
al., 2004; Goldbogen et al., 2013a, 2013b). Variations in dive behavior
may reflect interruptions in biologically significant activities (e.g.,
foraging) or they may be of little biological significance. The impact
of an alteration to dive behavior resulting from an acoustic exposure
depends on what the animal is doing at the time of the exposure and the
type and magnitude of the response.
Disruption of feeding behavior can be difficult to correlate with
anthropogenic sound exposure, so it is usually inferred by observed
displacement from known foraging areas, the appearance of secondary
indicators (e.g., bubble nets or sediment plumes), or changes in dive
behavior. As for other types of behavioral response, the frequency,
duration, and temporal pattern of signal presentation, as well as
differences in species sensitivity, are likely contributing factors to
differences in response in any given circumstance (e.g., Croll et al.,
2001; Nowacek et al., 2004; Madsen et al., 2006; Yazvenko et al.,
2007). A determination of whether foraging disruptions incur fitness
consequences would require information on or estimates of the energetic
requirements of the affected individuals and the relationship between
prey availability, foraging effort and success, and the life history
stage of the animal.
Variations in respiration naturally vary with different behaviors
and alterations to breathing rate as a function of acoustic exposure
can be expected to co-occur with other behavioral reactions, such as a
flight response or an alteration in diving. However, respiration rates
in and of themselves may be representative of annoyance or an acute
stress response. Various studies have shown that respiration rates may
either be unaffected or could increase, depending on the species and
signal characteristics, again highlighting the importance in
understanding species differences in the tolerance of underwater noise
when determining the potential for impacts resulting from anthropogenic
sound exposure (e.g., Kastelein et al., 2001, 2005, 2006; Gailey et
al., 2007). For example, harbor porpoise' respiration rate increased in
response to pile driving sounds at and above a received broadband Sound
Pressure Level (SPL) of 136 dB (zero-peak SPL: 151 dB re 1 micropascal
([mu]Pa); SEL of a single strike: 127 dB re 1 [mu]Pa\2\-s) (Kastelein
et al., 2013).
Marine mammals vocalize for different purposes and across multiple
modes, such as whistling, echolocation click production, calling, and
singing. Changes in vocalization behavior in response to anthropogenic
noise can occur for any of these modes and may result from a need to
compete with an increase in background noise or may reflect increased
vigilance or a startle response. For example, in the presence of
potentially masking signals, humpback whales and killer whales have
been observed to increase the length of their songs (Miller et al.,
2000; Fristrup et al., 2003) or vocalizations (Foote et al., 2004),
respectively, while North Atlantic right whales (Eubalaena
[[Page 11290]]
glacialis) have been observed to shift the frequency content of their
calls upward while reducing the rate of calling in areas of increased
anthropogenic noise (Parks et al., 2007). In some cases, animals may
cease sound production during production of aversive signals (Bowles et
al., 1994).
Avoidance is the displacement of an individual from an area or
migration path as a result of the presence of a sound or other
stressors, and is one of the most obvious manifestations of disturbance
in marine mammals (Richardson et al., 1995). For example, gray whales
are known to change direction--deflecting from customary migratory
paths--in order to avoid noise from seismic surveys (Malme et al.,
1984). Avoidance may be short-term, with animals returning to the area
once the noise has ceased (e.g., Bowles et al., 1994; Goold, 1996;
Stone et al., 2000; Morton and Symonds, 2002; Gailey et al., 2007).
Longer-term displacement is possible, however, which may lead to
changes in abundance or distribution patterns of the affected species
in the affected region if habituation to the presence of the sound does
not occur (e.g., Blackwell et al., 2004; Bejder et al., 2006; Teilmann
et al., 2006).
A flight response is a dramatic change in normal movement to a
directed and rapid movement away from the perceived location of a sound
source. The flight response differs from other avoidance responses in
the intensity of the response (e.g., directed movement, rate of
travel). Relatively little information on flight responses of marine
mammals to anthropogenic signals exist, although observations of flight
responses to the presence of predators have occurred (Connor and
Heithaus, 1996; Bowers et al., 2018). The result of a flight response
could range from brief, temporary exertion and displacement from the
area where the signal provokes flight to, in extreme cases, marine
mammal strandings (England et al., 2001). However, it should be noted
that response to a perceived predator does not necessarily invoke
flight (Ford and Reeves, 2008), and whether individuals are solitary or
in groups may influence the response.
Behavioral disturbance can also impact marine mammals in more
subtle ways. Increased vigilance may result in costs related to
diversion of focus and attention (i.e., when a response consists of
increased vigilance, it may come at the cost of decreased attention to
other critical behaviors such as foraging or resting). These effects
have generally not been demonstrated for marine mammals, but studies
involving fishes and terrestrial animals have shown that increased
vigilance may substantially reduce feeding rates (e.g., Beauchamp and
Livoreil, 1997; Fritz et al., 2002; Purser and Radford, 2011). In
addition, chronic disturbance can cause population declines through
reduction of fitness (e.g., decline in body condition) and subsequent
reduction in reproductive success, survival, or both (e.g., Harrington
and Veitch, 1992; Daan et al., 1996; Bradshaw et al., 1998). However,
Ridgway et al. (2006) reported that increased vigilance in bottlenose
dolphins exposed to sound over a 5-day period did not cause any sleep
deprivation or stress effects.
Many animals perform vital functions, such as feeding, resting,
traveling, and socializing, on a diel cycle (24-hour cycle). Disruption
of such functions resulting from reactions to stressors such as sound
exposure are more likely to be significant if they last more than one
diel cycle or recur on subsequent days (Southall et al., 2007).
Consequently, a behavioral response lasting less than 1 day and not
recurring on subsequent days is not considered particularly severe
unless it could directly affect reproduction or survival (Southall et
al., 2007). Note that there is a difference between multi-day
substantive (i.e., meaningful) behavioral reactions and multi-day
anthropogenic activities. For example, just because an activity lasts
for multiple days does not necessarily mean that individual animals are
either exposed to activity-related stressors for multiple days or,
further, exposed in a manner resulting in sustained multi-day
substantive behavioral responses.
Stress Responses--An animal's perception of a threat may be
sufficient to trigger stress responses consisting of some combination
of behavioral responses, autonomic nervous system responses,
neuroendocrine responses, or immune responses (e.g., Seyle, 1950;
Moberg, 2000). In many cases, an animal's first and sometimes most
economical (in terms of energetic costs) response is behavioral
avoidance of the potential stressor. Autonomic nervous system responses
to stress typically involve changes in heart rate, blood pressure, and
gastrointestinal activity. These responses have a relatively short
duration and may or may not have a significant long-term effect on an
animal's fitness.
Neuroendocrine stress responses often involve the hypothalamus-
pituitary-adrenal system. Virtually all neuroendocrine functions that
are affected by stress--including immune competence, reproduction,
metabolism, and behavior--are regulated by pituitary hormones. Stress-
induced changes in the secretion of pituitary hormones have been
implicated in failed reproduction, altered metabolism, reduced immune
competence, and behavioral disturbance (e.g., Moberg, 1987; Blecha,
2000). Increases in the circulation of glucocorticoids are also equated
with stress (Romano et al., 2004).
The primary distinction between stress (which is adaptive and does
not normally place an animal at risk) and ``distress'' is the cost of
the response. During a stress response, an animal uses glycogen stores
that can be quickly replenished once the stress is alleviated. In such
circumstances, the cost of the stress response would not pose serious
fitness consequences. However, when an animal does not have sufficient
energy reserves to satisfy the energetic costs of a stress response,
energy resources must be diverted from other functions. This state of
distress will last until the animal replenishes its energetic reserves
sufficient to restore normal function.
Relationships between these physiological mechanisms, animal
behavior, and the costs of stress responses are well-studied through
controlled experiments and for both laboratory and free-ranging animals
(e.g., Holberton et al., 1996; Hood et al., 1998; Jessop et al., 2003;
Krausman et al., 2004; Lankford et al., 2005). Stress responses due to
exposure to anthropogenic sounds or other stressors and their effects
on marine mammals have also been reviewed (Fair and Becker, 2000;
Romano et al., 2002b) and, more rarely, studied in wild populations
(e.g., Romano et al., 2002a). For example, Rolland et al. (2012) found
that noise reduction from reduced ship traffic in the Bay of Fundy was
associated with decreased stress in North Atlantic right whales. These
and other studies lead to a reasonable expectation that some marine
mammals will experience physiological stress responses upon exposure to
acoustic stressors and that it is possible that some of these would be
classified as ``distress.'' In addition, any animal experiencing TTS
would likely also experience stress responses (NRC, 2003), however
distress is an unlikely result of this project based on observations of
marine mammals during previous, similar projects in the area.
Auditory Masking--Since many marine mammals rely on sound to find
prey, moderate social interactions, and facilitate mating (Tyack,
2008), noise from anthropogenic sound sources can interfere with these
functions, but only if the noise spectrum overlaps with the hearing
sensitivity of the receiving marine mammal (Southall et al., 2007;
[[Page 11291]]
Clark et al., 2009; Hatch et al., 2012). Chronic exposure to excessive,
though not high-intensity, noise could cause masking at particular
frequencies for marine mammals that utilize sound for vital biological
functions (Clark et al., 2009). Acoustic masking is when other noises
such as from human sources interfere with an animal's ability to
detect, recognize, or discriminate between acoustic signals of interest
(e.g., those used for intraspecific communication and social
interactions, prey detection, predator avoidance, navigation)
(Richardson et al., 1995; Erbe et al., 2016). Therefore, under certain
circumstances, marine mammals whose acoustical sensors or environment
are being severely masked could also be impaired from maximizing their
performance fitness in survival and reproduction. The ability of a
noise source to mask biologically important sounds depends on the
characteristics of both the noise source and the signal of interest
(e.g., signal-to-noise ratio, temporal variability, direction), in
relation to each other and to an animal's hearing abilities (e.g.,
sensitivity, frequency range, critical ratios, frequency
discrimination, directional discrimination, age or TTS hearing loss),
and existing ambient noise and propagation conditions (Hotchkin and
Parks, 2013).
Under certain circumstances, marine mammals experiencing
significant masking could also be impaired from maximizing their
performance fitness in survival and reproduction. Therefore, when the
coincident (masking) sound is human-made, it may be considered
harassment when disrupting or altering critical behaviors. It is
important to distinguish TTS and PTS, which persist after the sound
exposure, from masking, which occurs during the sound exposure. Because
masking (without resulting in TS) is not associated with abnormal
physiological function, it is not considered a physiological effect,
but rather a potential behavioral effect (though not necessarily one
that would be associated with harassment).
The frequency range of the potentially masking sound is important
in determining any potential behavioral impacts. For example, low-
frequency signals may have less effect on high-frequency echolocation
sounds produced by odontocetes but are more likely to affect detection
of mysticete communication calls and other potentially important
natural sounds such as those produced by surf and some prey species.
The masking of communication signals by anthropogenic noise may be
considered as a reduction in the communication space of animals (e.g.,
Clark et al., 2009) and may result in energetic or other costs as
animals change their vocalization behavior (e.g., Miller et al., 2000;
Foote et al., 2004; Parks et al., 2007; Di Iorio and Clark, 2010; Holt
et al., 2009). Masking can be reduced in situations where the signal
and noise come from different directions (Richardson et al., 1995),
through amplitude modulation of the signal, or through other
compensatory behaviors (Hotchkin and Parks, 2013). Masking can be
tested directly in captive species (e.g., Erbe, 2008), but in wild
populations it must be either modeled or inferred from evidence of
masking compensation. There are few studies addressing real-world
masking sounds likely to be experienced by marine mammals in the wild
(e.g., Branstetter et al., 2013).
Marine mammals at or near the project site may be exposed to
anthropogenic noise, which may lead to some habituation, but is also a
source of masking. Vocalization changes may result from a need to
compete with an increase in background noise and include increasing the
source level, modifying the frequency, increasing the call repetition
rate of vocalizations, or ceasing to vocalize in the presence of
increased noise (Hotchkin and Parks, 2013).
Masking is more likely to occur in the presence of broadband,
relatively continuous noise sources such as borehole drilling. Energy
distribution of borehole drilling covers a broad frequency spectrum,
and sound from borehole drilling would be within the audible range of
pinnipeds and cetaceans present in the proposed action area. While some
construction during the USACE's activities may mask some acoustic
signals that are relevant to the daily behavior of marine mammals, the
short-term duration and time of year make it very unlikely that the
fitness of individual marine mammals would be impacted.
Airborne Acoustic Effects--Airborne noise would primarily be an
issue for pinnipeds that are swimming or hauled out near the project
site within the range of noise levels elevated above the acoustic
criteria. We recognize that pinnipeds in the water could be exposed to
airborne sound that may result in behavioral harassment when looking
with their heads above water. Most likely, airborne sound would cause
behavioral responses similar to those discussed above in relation to
underwater sound. For instance, anthropogenic sound could cause hauled
out pinnipeds to exhibit changes in their normal behavior, such as
reduction in vocalizations, or cause them to temporarily abandon the
area and move further from the source. However, these animals would
previously have been ``taken'' because of exposure to underwater sound
above the behavioral harassment thresholds, which are in all cases
larger than those associated with airborne sound. Thus, the behavioral
harassment of these animals is already accounted for in these estimates
of potential take. Therefore, we do not believe that authorization of
incidental take resulting from airborne sound for pinnipeds is
warranted, and airborne sound is not discussed further. Cetaceans are
not expected to be exposed to airborne sounds that would result in
harassment as defined under the MMPA.
Marine Mammal Habitat Effects
The USACE's proposed construction activities could have localized,
temporary impacts on marine mammal habitat and their prey by increasing
in-water SPLs and slightly decreasing water quality. Increased noise
levels may affect acoustic habitat (see Auditory Masking) and adversely
affect marine mammal prey in the vicinity of the project area (see
discussion below). During LPT and borehole drilling, elevated levels of
underwater noise would ensonify a portion of the embayment between Old
Jetty and North Rookery, where activities are planned, where both fish
and mammals occur and could affect foraging success. Additionally,
marine mammals may avoid the area during survey activities; however,
displacement due to noise is expected to be temporary and is not
expected to result in long-term effects to the individuals or
populations. In-water geotechnical survey activities could also cause
short-term effects on water quality due to increased turbidity. It is
not expected that turbidity associated with geotechnical surveys would
be different from pile installation, which is typically localized to
about a 25 ft (7.6 m) radius around the pile (Everitt et al., 1980). It
is expected that the sediments of the project site would settle out
rapidly when disturbed. Cetaceans are not expected to be close enough
to the geotechnical survey areas to experience effects of turbidity,
and any pinnipeds could avoid localized areas of turbidity.
In-water Construction Effects on Potential Foraging Habitat--The
proposed activities would not result in permanent impacts to habitats
used directly by marine mammals. The total seafloor area affected by
geotechnical survey activities is small compared to the vast foraging
areas available to
[[Page 11292]]
marine mammals, and the localized areas affected by the activity are
not of particular value.
Avoidance by potential prey (i.e., fish or, in the case of
transient killer whales, other marine mammals) of the immediate area
due to the temporary loss of this foraging habitat is also possible.
The duration of fish and marine mammal avoidance of this area after
geotechnical survey activities is unknown, but a rapid return to normal
recruitment, distribution, and behavior is anticipated. Any behavioral
avoidance by fish or marine mammals of the disturbed area would still
leave significantly large areas of fish and marine mammal foraging
habitat in the nearby vicinity.
In-water Construction Effects on Potential Prey--Sound may affect
marine mammals through impacts on the abundance, behavior, or
distribution of prey species (e.g., crustaceans, cephalopods, fish,
zooplankton). Marine mammal prey varies by species, season, and
location and, for some, is not well documented. Here, we describe
studies regarding the effects of noise on known marine mammal prey.
Fish utilize the soundscape and components of sound in their
environment to perform important functions such as foraging, predator
avoidance, mating, and spawning (e.g., Zelick et al., 1999; Fay, 2009).
Depending on their hearing anatomy and peripheral sensory structures,
which vary among species, fishes hear sounds using pressure and
particle motion sensitivity capabilities and detect the motion of
surrounding water (Fay et al., 2008). The potential effects of noise on
fishes depends on the overlapping frequency range, distance from the
sound source, water depth of exposure, and species-specific hearing
sensitivity, anatomy, and physiology. Key impacts to fishes may include
behavioral responses, hearing damage, barotrauma (pressure-related
injuries), and mortality.
Fish react to sounds which are especially strong and/or
intermittent low-frequency sounds, and behavioral responses such as
flight or avoidance are the most likely effects. Short duration, sharp
sounds can cause overt or subtle changes in fish behavior and local
distribution. The reaction of fish to noise depends on the
physiological state of the fish, past exposures, motivation (e.g.,
feeding, spawning, migration), and other environmental factors.
Hastings and Popper (2005) identified several studies that suggest fish
may relocate to avoid certain areas of sound energy. Additional studies
have documented effects of underwater anthropogenic noise on fish,
although several are based on studies in support of large, multiyear
bridge construction projects (e.g., Popper and Hastings, 2009; Scholik
and Yan 2001; Scholik and Yan 2002). Several studies have demonstrated
that impulse sounds might affect the distribution and behavior of some
fishes, potentially impacting foraging opportunities or increasing
energetic costs (e.g., Fewtrell and McCauley, 2012; Pearson et al.,
1992; Skalski et al., 1992; Santulli et al., 1999; Paxton et al.,
2017). However, some studies have shown no or slight reaction to
impulse sounds (e.g., Pena et al., 2013; Wardle et al., 2001; Jorgenson
and Gyselman, 2009; Cott et al., 2012). More commonly, though, the
impacts of noise on fish are temporary.
SPLs of sufficient strength have been known to cause injury to fish
and fish mortality. However, in most fish species, hair cells in the
ear continuously regenerate and loss of auditory function likely is
restored when damaged cells are replaced with new cells. Halvorsen et
al. (2012a) showed that a TTS of 4-6 dB was recoverable within 24 hours
for one species. Impacts would be most severe when the individual fish
is close to the source and when the duration of exposure is long.
Injury caused by barotrauma can range from slight to severe and can
cause death, and is most likely for fish with swim bladders. Barotrauma
injuries have been documented during controlled exposure to impact pile
driving (Halvorsen et al., 2012b; Casper et al., 2013).
The greatest potential impact to fishes during geotechnical survey
activities would occur during LPT sampling, which is estimated to occur
on up to 15 days for a maximum of 1 hour and 3600 strikes per day. In-
water construction activities would only occur during daylight hours,
allowing fish to forage and transit the project area in the evening.
Borehole drilling would possibly elicit behavioral reactions from
fishes such as temporary avoidance of the area but is unlikely to cause
injuries to fishes or have persistent effects on local fish
populations.
The most likely impact to fishes from geotechnical survey
activities in the project area would be temporary behavioral avoidance
of the area. The duration of fish avoidance of the area after
geotechnical survey activity stops is unknown but a rapid return to
normal recruitment, distribution, and behavior is anticipated. There
are times of known seasonal marine mammal foraging when fish are
aggregating but the impacted areas are small portions of the total
foraging habitats available in the regions. In general, impacts to
marine mammal prey species are expected to be minor and temporary.
Further, it is anticipated that preparation activities for geotechnical
surveys and upon initial startup of devices would cause fish to move
away from the affected area where injuries may occur. Therefore,
relatively small portions of the proposed project area would be
affected for short periods of time, and the potential for effects on
fish to occur would be temporary and limited to the duration of
sound[hyphen]generating activities.
In summary, given the short daily duration of sound associated with
individual geotechnical survey events and the relatively small areas
being affected, geotechnical survey activities associated with the
proposed action are not likely to have a permanent adverse effect on
any fish habitat, or populations of fish species. Any behavioral
avoidance by fish of the disturbed area would still leave significantly
large areas of fish and marine mammal foraging habitat in the nearby
vicinity. Thus, we conclude that impacts of the specified activity are
not likely to have more than short-term adverse effects on any prey
habitat or populations of prey species. Further, any impacts to marine
mammal habitat are not expected to result in significant or long-term
consequences for individual marine mammals, or to contribute to adverse
impacts on their populations.
Estimated Take of Marine Mammals
This section provides an estimate of the number of incidental takes
proposed for authorization through the IHA, which will inform NMFS'
consideration of ``small numbers,'' the negligible impact
determinations, and impacts on subsistence uses.
Harassment is the only type of take expected to result from these
activities. Except with respect to certain activities not pertinent
here, section 3(18) of the MMPA defines ``harassment'' as any act of
pursuit, torment, or annoyance, which (i) has the potential to injure a
marine mammal or marine mammal stock in the wild (Level A harassment);
or (ii) has the potential to disturb a marine mammal or marine mammal
stock in the wild by causing disruption of behavioral patterns,
including, but not limited to, migration, breathing, nursing, breeding,
feeding, or sheltering (Level B harassment).
Authorized takes would primarily be by Level B harassment, as use
of acoustic sources (LPT and borehole drilling) has the potential to
result in disruption of behavioral patterns for individual marine
mammals. There is also some potential for auditory injury
[[Page 11293]]
(AUD INJ) (Level A harassment) to result, for northern fur seal because
fur seals are common in the immediate vicinity of the planned activity
and predicted AUD INJ are larger than planned shutdown zones. AUD INJ
is unlikely to occur for other species. The proposed mitigation and
monitoring measures are expected to minimize the severity of the taking
to the extent practicable.
As described previously, no serious injury or mortality is
anticipated or proposed to be authorized for this activity. Below, we
describe how the proposed take numbers are estimated.
For acoustic impacts, generally speaking, we estimate take by
considering: (1) acoustic criteria above which NMFS believes the best
available science indicates marine mammals will likely be behaviorally
harassed or incur some degree of AUD INJ; (2) the area or volume of
water that will be ensonified above these levels in a day; (3) the
density or occurrence of marine mammals within these ensonified areas;
and, (4) the number of days of activities. We note that while these
factors can contribute to a basic calculation to provide an initial
prediction of potential takes, additional information that can
qualitatively inform take estimates is also sometimes available (e.g.,
previous monitoring results or average group size). Below, we describe
the factors considered here in more detail and present the proposed
take estimates.
Acoustic Criteria
NMFS recommends the use of acoustic criteria that identify the
received level of underwater sound above which exposed marine mammals
would be reasonably expected to be behaviorally harassed (equated to
Level B harassment) or to incur AUD INJ of some degree (equated to
Level A harassment). We note that the criteria for AUD INJ, as well as
the names of two hearing groups, have been recently updated (NMFS 2024)
as reflected below in the Level A harassment section.
Level B Harassment--Though significantly driven by received level,
the onset of behavioral disturbance from anthropogenic noise exposure
is also informed to varying degrees by other factors related to the
source or exposure context (e.g., frequency, predictability, duty
cycle, duration of the exposure, signal-to-noise ratio, distance to the
source), the environment (e.g., bathymetry, other noises in the area,
predators in the area), and the receiving animals (hearing, motivation,
experience, demography, life stage, depth) and can be difficult to
predict (e.g., Southall et al., 2007, 2021; Ellison et al., 2012).
Based on what the available science indicates and the practical need to
use a threshold based on a metric that is both predictable and
measurable for most activities, NMFS typically uses a generalized
acoustic threshold based on received level to estimate the onset of
behavioral harassment. NMFS generally predicts that marine mammals are
likely to be behaviorally harassed in a manner considered to be Level B
harassment when exposed to underwater anthropogenic noise above root-
mean-squared pressure received levels (RMS SPL) of 120 dB (referenced
to 1 micropascal (re 1 [mu]Pa)) for continuous (e.g., vibratory pile
driving, drilling) and above RMS SPL 160 dB re 1 [mu]Pa for non-
explosive impulsive (e.g., seismic airguns) or intermittent (e.g.,
scientific sonar) sources. Generally speaking, Level B harassment take
estimates based on these behavioral harassment thresholds are expected
to include any likely takes by TTS as, in most cases, the likelihood of
TTS occurs at distances from the source less than those at which
behavioral harassment is likely. TTS of a sufficient degree can
manifest as behavioral harassment, as reduced hearing sensitivity and
the potential reduced opportunities to detect important signals
(conspecific communication, predators, prey) may result in changes in
behavior patterns that would not otherwise occur.
USACE's geotechnical survey activities includes the use of
continuous (borehole drilling) and impulsive (LPT) sources, and
therefore the RMS SPL thresholds of 120 and 160 dB re 1 [mu]Pa,
respectively are applicable.
Level A Harassment--NMFS' Updated Technical Guidance for Assessing
the Effects of Anthropogenic Sound on Marine Mammal Hearing (Version
3.0) (Updated Technical Guidance, 2024) identifies dual criteria to
assess AUD INJ (Level A harassment) to five different underwater marine
mammal groups (based on hearing sensitivity) as a result of exposure to
noise from two different types of sources (impulsive or non-impulsive).
USACE's proposed activity includes the use of impulsive (i.e., LPT) and
non-impulsive (i.e., borehole drilling) sources.
The 2024 Updated Technical Guidance criteria include both updated
thresholds and updated weighting functions for each hearing group. The
thresholds are provided in the table below. The references, analysis,
and methodology used in the development of the criteria are described
in NMFS' 2024 Updated Technical Guidance, which may be accessed at:
https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance-other-acoustic-tools.
Table 4--Thresholds Identifying the Onset of Auditory Injury
----------------------------------------------------------------------------------------------------------------
AUD INJ onset acoustic thresholds \*\ (received level)
Hearing group ------------------------------------------------------------------------
Impulsive Non-impulsive
----------------------------------------------------------------------------------------------------------------
Low-Frequency (LF) Cetaceans........... Cell 1: Lpk,flat 222 dB; Cell 2: LE,LF,24h: 197 dB.
LE,LF,24h:: 183 dB.
High-Frequency (HF) Cetaceans.......... Cell 3: Lpk,flat 230 dB; Cell 4: LE,HF,24h: 201 dB.
LE,HF,24h: 193 dB.
Very High-Frequency (VHF) Cetaceans.... Cell 5: Lpk,flat 202 dB; Cell 6: LE,VHF,24h: 181 dB.
LE,VHF,24h: 159 dB.
Phocid Pinnipeds (PW) (Underwater)..... Cell 7: Lpk,flat 223 dB; Cell 8: LE,PW,24h: 195 dB.
LE,PW,24h: 183 dB.
Otariid Pinnipeds (OW)................. Cell 9: Lpk,flat 230 dB; Cell 10: LE,OW,24h: 199 dB.
(Underwater)........................... LE,OW,24h: 185 dB.
----------------------------------------------------------------------------------------------------------------
* Dual metric criteria for impulsive sounds: Use whichever criteria results in the larger isopleth for
calculating AUD INJ onset. If a non-impulsive sound has the potential of exceeding the peak sound pressure
level criteria associated with impulsive sounds, the PK SPL criteria are recommended for consideration for non-
impulsive sources.
[[Page 11294]]
Note: Peak sound pressure level (Lp,0-pk) has a reference value of 1 [mu]Pa, and weighted cumulative sound
exposure level (LE,p) has a reference value of 1 [mu]Pa\2\s. In this table, criteria are abbreviated to be
more reflective of International Organization for Standardization (ISO) standards (ISO 2017; ISO 2020). The
subscript ``flat'' is being included to indicate peak sound pressure are flat weighted or unweighted within
the generalized hearing range of marine mammals underwater (i.e., 7 Hz to 165 kHz). The subscript associated
with cumulative sound exposure level criteria indicates the designated marine mammal auditory weighting
function (LF, HF, and VHF cetaceans, and PW and OW pinnipeds) and that the recommended accumulation period is
24 hours. The weighted cumulative sound exposure level criteria could be exceeded in a multitude of ways
(i.e., varying exposure levels and durations, duty cycle). When possible, it is valuable for action proponents
to indicate the conditions under which these criteria will be exceeded.
Ensonified Area
Here, we describe operational and environmental parameters of the
activity that are used in estimating the area ensonified above the
acoustic thresholds, including source levels and transmission loss
coefficient.
The sound field in the project area is the existing background
noise plus additional construction noise from the proposed project.
Marine mammals are expected to be affected via sound generated by the
primary components of the project (i.e., LPT and borehole drilling).
Sound Source Levels of Proposed Activities-- The intensity of
geotechnical survey activity sounds is greatly influenced by factors
such as the size of hammers and the physical environment (e.g.,
sediment type) in which the activity takes place. The USACE evaluated
sound source level (SL) measurements available for similar geotechnical
surveys to determine suitable proxies for the planned activities. The
proxy source levels initially proposed by USACE were less conservative
compared to what might be realized by the actual activities taking
place, as the values were derived in one case, from a project that was
conducted in a dissimilar sediment type from a jacked up drill rig, and
in another case, from a project that did not report its parameters and
environmental characteristics. NMFS has instead relied on alternative
proxy SLs in our evaluation of the impacts of the USACE's planned
activities (table 1) on marine mammals, with USACE concurrence.
Table 5--Estimates of Mean Underwater Sound Levels Generated During Geotechnical Surveys
----------------------------------------------------------------------------------------------------------------
Reference
dB RMS dB Peak dB SEL distance (m) Reference
----------------------------------------------------------------------------------------------------------------
LPT........................... 197 213 182 1 Huang et al.,
2023.
Borehole Drilling............. 155.9 N/A N/A
----------------------------------------------------------------------------------------------------------------
Note: dB peak = peak sound level; rms = root mean square; SEL = sound exposure level.
TL is the decrease in acoustic intensity as an acoustic pressure
wave propagates out from a source. TL parameters vary with frequency,
temperature, sea conditions, current, source and receiver depth, water
depth, water chemistry, and bottom composition and topography. The
general formula for underwater TL is:
TL = B x Log10 (R1/R2),
Where
TL = transmission loss in dB
B = transmission loss coefficient
R1 = the distance of the modeled SPL from the driven
pile, and
R2 = the distance from the driven pile of the initial
measurement
Absent site-specific acoustical monitoring with differing measured
TL, a practical spreading value of 15 is used as the TL coefficient in
the above formula. Site-specific TL data for the Sitka Sound are not
available; therefore, the default coefficient of 15 is used to
determine the distances to the Level A harassment and Level B
harassment thresholds.
The ensonified area associated with Level A harassment is more
technically challenging to predict due to the need to account for a
duration component. Therefore, NMFS developed an optional User
Spreadsheet tool to accompany the 2024 Updated Technical Guidance that
can be used to relatively simply predict an isopleth distance for use
in conjunction with marine mammal density or occurrence to help predict
potential takes. We note that because of some of the assumptions
included in the methods underlying this optional tool, we anticipate
that the resulting isopleth estimates are typically going to be
overestimates of some degree, which may result in an overestimate of
potential take by Level A harassment. However, this optional tool
offers the best way to estimate isopleth distances when more
sophisticated modeling methods are not available or practical. For
stationary sources such as geotechnical survey activities (LPT and
borehole drilling), the optional User Spreadsheet tool predicts the
distance at which, if a marine mammal remained at that distance for the
duration of the activity, it would be expected to incur AUD INJ. Inputs
used in the optional User Spreadsheet tool (e.g., number of holes per
day, duration, and strikes/hole) are presented in table 6 and the
resulting estimated isopleths, are reported below in table 7.
Table 6--User Spreadsheet Inputs
------------------------------------------------------------------------
Impact Vibratory
---------------------------------------
LPT Borehole drilling
------------------------------------------------------------------------
Spreadsheet Tab Used............ E.1) Impact Pile A.1) Vibratory
Driving. Pile Driving.
Source Level (SPL).............. 182 SEL........... 155.9 RMS.
---------------------------------------
Transmission Loss Coefficient... 15
---------------------------------------
Weighting Factor Adjustment 2................. 2.5.
(kHz).
Activity Duration per day 60................ 540.
(minutes).
[[Page 11295]]
Number of strikes per pile...... 3,600............. N/A
---------------------------------------
Number of piles per day......... 1
Distance of sound pressure level 1
measurement.
------------------------------------------------------------------------
Table 7--Level A Harassment and Level B Harassment Isopleths and Associated Areas From Geotechnical Surveys
--------------------------------------------------------------------------------------------------------------------------------------------------------
Level A harassment: isopleths (m) Level B
Activity type -------------------------------------------------------------------------------- harassment
LF HF VHF PW OW isopleth (m)
--------------------------------------------------------------------------------------------------------------------------------------------------------
LPT..................................................... 200.5 25.6 310.2 178.1 66.4 293
Drilling................................................ 1.8 0.7 1.5 2.3 0.8 247
--------------------------------------------------------------------------------------------------------------------------------------------------------
Abbreviations: LF = low-frequency cetaceans, HF = high-frequency cetaceans, VHF = very high-frequency cetaceans, PW = phocid pinnipeds in water, OW =
otariid pinnipeds in water.
Level A harassment zones are typically smaller than Level B
harassment zones. Calculation of Level A harassment isopleths include a
duration component, which in the case of LPT, is estimated through the
total number of daily strikes and the associated pulse duration. For a
stationary sound source such as LPT, we assume there that an animal is
exposed to all of the strikes expected within a 24-hour period.
Calculation of a Level B harassment zone does not include a duration
component.
Marine Mammal Occurrence and Take Estimation
In this section, we provide information about the occurrence of
marine mammals, including density or other relevant information which
will inform the take calculations. We also describe how the information
provided above is synthesized to produce a quantitative estimate of the
take that is reasonably likely to occur and proposed for authorization.
Potential exposures to LPT and borehole drilling noise for each
acoustic threshold were estimated using data reported by the USACE from
monitoring events conducted on 5 days across April and June 2024 (table
8). Northern fur seal were the only pinnipeds observed on land. The
USACE reported an estimate of a single daily point count of the number
of northern fur seals present at north rookery and along the shoreline
towards the Old Jetty. For pinnipeds observed in the water (northern
fur seal, Steller sea lion, and harbor seal), USACE reported the total
number of each species observed over the course of a day. Individual
sightings of pinniped groups in the water were not reported. Northern
fur seal in the water were described to be moving from west to east.
Steller sea lion were described to be observed near the Old Jetty in
groups up to 8 to 10, and were passing through rather than lingering.
On 3 days, groups of up to eight harbor seal were observed inside the
Old Jetty.
Table 8--Monitoring Data Collected and Reported by USACE Between Old Jetty and North Rookery in 2024
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Daily total marine mammals observed in water Daily estimates of marine mammals observed on land
Hours of Total hours of \1\ --------------------------------------------------------------------------
Date observation observation ------------------------------------------------
NOFS HASL STSL NOFS \2\ HASL STSL
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
4/23/2024............................ 14:30-22:00 7.5 16 6 3 No Data................ No Data................ No Data.
4/24/2024............................ 08:15-22:30 14.25 22 8 11 126.................... 0...................... 0.
4/25/2024............................ 08:30-23:45 15.25 32 3 14 No Data................ No Data................ No Data.
6/14/2024............................ 18:00-0000 6 98 0 5 245.................... 0...................... 0.
6/15/2024............................ 09:00-23:45 13.75 110 0 4 300.................... 0...................... 0.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Individual sightings of groups of marine mammals throughout the observation period were not reported.
\2\ The USACE indicated that they counted northern fur seal hauled out along approximately \1/3\ of the rookery and extrapolated this number to estimate the total number of seals present along
the rest of the shoreline.
The take estimate was determined using the following equation: take
estimate = number of expected animals * number of planned survey days.
Northern Fur Seal
Initially, the USACE used both land-based and in-water counts to
estimate the number of expected northern fur seals to be taken each
survey day. For the six boreholes closest to North Rookery, USACE used
the maximum number estimated on the beach across all five surveys (n =
300) and maximum number estimated in the water across all five surveys
(n = 110). For the remaining nine boreholes, USACE assumed half the
maximum number on the shore across all five surveys would be taken (n =
150) and the maximum number estimated in the water across all five
surveys (n = 110). NMFS agrees with USACE's rationale for estimating
take using on-land numbers, but disagrees that in-water counts should
be used in take estimates. These observations were not recorded in
concert with land-based observations and as such would double-count the
number of northern fur seals that might be taken. Additionally since
fine-scale data regarding pinniped use in the area are not available,
NMFS finds that it is more appropriate to base
[[Page 11296]]
take estimates on the maximum number estimated on land for all borehole
locations and the USACE agreed. The USACE concurred with this approach.
As noted previously, NMFS assumes, that the number of hauled out
northern fur seals at north rookery represent approximately one-third
of the total population of northern fur seal in the area (Williams
2024, personal communication), and as such, the maximum count of land-
based seals is multiplied by 3. As such, a total of 13,500 takes by
Level B harassment of northern fur seal are proposed for authorization
(15 construction days x 300 northern fur seals * 3 = 13,500 takes by
Level B harassment.
During LPT activities, the Level A harassment zone (66.4 m) is
larger than the shutdown zone (50 m) for northern fur seal. As such,
and given the frequent occurrence of fur seals in the immediate
vicinity of the project area, it is possible that northern fur seal may
enter the Level A harassment zone and stay long enough to incur AUD INJ
before exiting. The ratio of the Level A harassment area that exceeds
the shutdown zone (0.007 km\2\) to the largest Level B harassment area
(0.27 km\2\) is 0.026. This activity is predicted to take place 10
percent of each survey day. As such, 35 takes by Level A harassment is
proposed for authorization (0.026 x 900 northern fur seal x 15 survey
days x .10 = 35 takes by Level A harassment).
Any individuals exposed to the higher levels associated with the
potential for PTS closer to the source might also be behaviorally
disturbed; however, for the purposes of quantifying take we do not
count those exposures of one individual as a take by both Level A
harassment and Level B harassment. Therefore, NMFS proposes to
authorize 35 takes by Level A harassment and 13,465 takes by Level B
harassment for northern fur seal, for a total of 13,500 takes.
Harbor Seal
To estimate take for harbor seal, USACE used the maximum number of
harbor seal observed in one day, across all survey days (n = 8).
Because harbor seal are uncommon in the area and were only observed
near the Old Jetty, USACE estimated take by Level B harassment to occur
on 7 of the 15 construction days to correspond with the surveys that
are completed closer to the Old Jetty. However, since fine-scale data
regarding harbor seal use in the area are not available, NMFS finds it
more appropriate to estimate that take by Level B harassment might
occur at any of the borehole locations, and USACE agreed. As such, 120
takes by Level B harassment are proposed for authorization (8 harbor
seal x 15 construction days). No takes by Level A harassment are
requested or proposed for authorization given the relative rarity of
harbor seal occurrence in conjunction with planned shutdown
requirements.
Steller Sea Lion
The spring-time occurrence of Steller sea lions on St. George
Island near the project area is highly variable across years. Typically
there are no Steller sea lions present on land adjacent to the bay
where the project is to occur in the spring, but occasionally they haul
out at sites across North Rookery (primarily the western end, but
extending east towards the work site), East Reef rookery, and East
Cliffs rookery in groups of up to 100 (Williams 2024, personal
communication). When present, they tend to travel through the project
area and do not linger. During monitoring events conducted on 5 days in
April and June 2024, USACE observed 3 to 14 Steller sea lions traveling
near the western portion of the project area each survey day. USACE
plans to shut down upon observation of Steller sea lions. Given the
plan to shut down, and because Steller sea lions inconsistently occur
in the project area, are conspicuous, and do not tend to linger, no
takes are expected to occur and none are proposed for authorization.
Killer Whale
Killer whale have been observed in nearshore habitats of the
Pribilofs including from viewing locations near the project site.
Killer whale are conspicuous and USACE plans to shut down upon
observation of killer whale nearing the Level B harassment zone.
Shutdown zones for killer whale have been established at 300 m during
borehole drilling and 400 m during LPT, whereas the calculated Level B
harassment zones are 247 m and 293 m, respectively. As such, no takes
by Level B or Level A harassment is requested or authorized.
Table 9--Take by Stock and Harassment Type and as a Percentage of Stock Abundance
----------------------------------------------------------------------------------------------------------------
Take as
Level A Level B percentage of
Species Stock harassment harassment stock
abundance
----------------------------------------------------------------------------------------------------------------
Harbor Seal........................... Pribilof................ 0 120 \1\ 52
Northern Fur Seal..................... E. Pacific.............. 35 13,465 2
Steller Sea Lion...................... Western DPS............. 0 0 0
Killer Whale.......................... Eastern North Pacific 0 0 0
Alaska Resident.
Eastern North Pacific 0 0 0
Gulf of Alaska,
Aleutian Islands and
Bering Sea Transient.
----------------------------------------------------------------------------------------------------------------
\1\ These numbers represent the estimated incidents of take, not the number of individuals taken (see Small
Numbers section).
Proposed Mitigation
In order to issue an IHA under section 101(a)(5)(D) of the MMPA,
NMFS must set forth the permissible methods of taking pursuant to the
activity, and other means of effecting the least practicable impact on
the species or stock and its habitat, paying particular attention to
rookeries, mating grounds, and areas of similar significance, and on
the availability of the species or stock for taking for certain
subsistence uses. NMFS regulations require applicants for incidental
take authorizations to include information about the availability and
feasibility (economic and technological) of equipment, methods, and
manner of conducting the activity or other means of effecting the least
practicable adverse impact upon the affected species or stocks, and
their habitat (50 CFR 216.104(a)(11)).
In evaluating how mitigation may or may not be appropriate to
ensure the least practicable adverse impact on species or stocks and
their habitat, as well as subsistence uses where applicable, NMFS
considers two primary factors:
(1) The manner in which, and the degree to which, the successful
implementation of the measure(s) is expected to reduce impacts to
marine
[[Page 11297]]
mammals, marine mammal species or stocks, and their habitat. This
considers the nature of the potential adverse impact being mitigated
(likelihood, scope, range). It further considers the likelihood that
the measure will be effective if implemented (probability of
accomplishing the mitigating result if implemented as planned), the
likelihood of effective implementation (probability implemented as
planned), and;
(2) The practicability of the measures for applicant
implementation, which may consider such things as cost, and impact on
operations.
Mitigation for Marine Mammals and Their Habitat
Temporal Work Restriction--Temporal restrictions in places where
marine mammals are concentrated, engaged in biologically important
behaviors, and/or present in sensitive life stages are effective
measures for reducing the magnitude and severity of human impacts. NMFS
is requiring a temporal work restriction to minimize the consequences
of noise exposure to northern fur seal at North Rookery incidental to
USACE's geotechnical surveys. This temporal work restriction is
expected to greatly reduce the number and severity of northern fur seal
takes that would otherwise occur should activities be conducted after
arrival of pregnant females to the area in mid-June.
Shutdown Zones--For all in-water survey activities, USACE proposes
to implement shutdowns within designated zones. The purpose of a
shutdown zone is generally to define an area within which shutdown of
the activity would occur upon sighting of a marine mammal (or in
anticipation of an animal entering the defined area). Shutdown zones
vary based on the activity type and marine mammal hearing group (table
10). For harbor seal, the shutdown zones are based on the estimated
Level A harassment isopleth. For northern fur seal, the shutdown zone
for LPT is set at 50 m (slightly less than the estimated Level A
harassment zone of 66 m) to minimize practicability concerns, i.e.,
that increased shutdowns may result in failure to complete the project
in a timely fashion (given that non-breeding male northern fur seal are
common in the project area).
Table 10--Proposed Shutdown Zones
--------------------------------------------------------------------------------------------------------------------------------------------------------
Shutdown zones (m)
-----------------------------------------------------------------------------------------------
OW
Activity -------------------------------
LF HF VHF PW Northern fur
seal Other OW
--------------------------------------------------------------------------------------------------------------------------------------------------------
Borehole Drilling....................................... 300 10 10 300
------------------------------------------------
LPT..................................................... 400 200 50 400
--------------------------------------------------------------------------------------------------------------------------------------------------------
Construction supervisors and crews, Protected Species Observers
(PSOs), and relevant USACE staff must avoid direct physical interaction
with marine mammals during construction activity. If a marine mammal
comes within 10 m of such activity, operations must cease and vessels
must reduce speed to the minimum level required to maintain steerage
and safe working conditions, as necessary to avoid direct physical
interaction. If an activity is delayed or halted due to the presence of
a marine mammal, the activity may not commence or resume until either
the animal has voluntarily exited and been visually confirmed beyond
the shutdown zone indicated in table 10, or 15 minutes have passed
without re-detection of the animal.
Finally, construction activities must be halted upon observation of
a species for which incidental take is not authorized or a species for
which incidental take has been authorized but the authorized number of
takes has been met entering or within any harassment zone. If a marine
mammal species not covered under the IHA enters a harassment zone, all
in-water activities will cease until the animal leaves the zone or has
not been observed for at least 15 minutes, and NMFS would be notified
about species and precautions taken. Borehole drilling and LPT will
proceed if the unauthorized species is observed leaving the harassment
zone or if 15 minutes have passed since the last observation.
Protected Species Observers (PSOs)--The number and placement of
PSOs during all construction activities (described in the Proposed
Monitoring and Reporting section) would ensure that the entire shutdown
zone is visible during all in-water LPT and borehole drilling
activities. In such cases, PSOs would monitor the shutdown zone and
beyond to the greatest extent practicable. USACE would employ at least
two PSOs for all geotechnical survey activities.
Monitoring for Level A and Level B Harassment--PSOs would monitor
the shutdown zones and beyond to the extent that PSOs can see.
Monitoring beyond the shutdown zones enables observers to be aware of
and communicate the presence of marine mammals in the project areas
outside the shutdown zones and thus prepare for a potential cessation
of activity should the animal enter the shutdown zone. If a marine
mammal enters either harassment zone, PSOs will document the marine
mammal's presence and behavior.
Pre- and Post-Activity Monitoring--Prior to the start of daily in-
water construction activity, or whenever a break in geotechnical survey
activities of 30 minutes or longer occurs, PSOs would observe the
shutdown zones and as much as the harassment zones as possible for a
period of 30 minutes. Pre-start clearance monitoring must be conducted
during periods of visibility sufficient for the lead PSO to determine
that the shutdown zones are clear of marine mammals. If the shutdown
zone is obscured by fog or poor lighting conditions, in-water
construction activity will not be initiated until the entire shutdown
zone is visible. Geotechnical survey activities may commence following
30 minutes of observation when the determination is made that the
shutdown zones are clear of marine mammals. If a marine mammal is
observed entering or within shutdown zones, geotechnical survey
activity must be delayed or halted. If geotechnical survey activities
are delayed or halted due to the presence of a marine mammal, the
activity may not commence or resume until either the animal has
voluntarily exited and been visually confirmed beyond the
[[Page 11298]]
shutdown zone or 15 minutes have passed without re-detection of the
animal. If a marine mammal for which take by Level B harassment is
authorized is present in the Level B harassment zone, activities may
begin.
Soft Start--Note that while NMFS typically requires soft starts for
impact pile driving activities, USACE indicated this mitigation measure
is not appropriate for LPT because it is not possible to decrease the
impact from the LPT because the number of blows per fixed distance
driven is an indicator of soil properties that are used in design.
Based on our evaluation of the applicant's proposed measures, NMFS
has preliminarily determined that the proposed mitigation measures
provide the means of effecting the least practicable impact on the
affected species or stocks and their habitat, paying particular
attention to rookeries, mating grounds, and areas of similar
significance, and on the availability of such species or stock for
subsistence.
Proposed Monitoring and Reporting
In order to issue an IHA for an activity, section 101(a)(5)(D) of
the MMPA states that NMFS must set forth requirements pertaining to the
monitoring and reporting of such taking. The MMPA implementing
regulations at 50 CFR 216.104(a)(13) indicate that requests for
authorizations must include the suggested means of accomplishing the
necessary monitoring and reporting that will result in increased
knowledge of the species and of the level of taking or impacts on
populations of marine mammals that are expected to be present while
conducting the activities. Effective reporting is critical both to
compliance as well as ensuring that the most value is obtained from the
required monitoring.
Monitoring and reporting requirements prescribed by NMFS should
contribute to improved understanding of one or more of the following:
Occurrence of marine mammal species or stocks in the area
in which take is anticipated (e.g., presence, abundance, distribution,
density);
Nature, scope, or context of likely marine mammal exposure
to potential stressors/impacts (individual or cumulative, acute or
chronic), through better understanding of: (1) action or environment
(e.g., source characterization, propagation, ambient noise); (2)
affected species (e.g., life history, dive patterns); (3) co-occurrence
of marine mammal species with the activity; or (4) biological or
behavioral context of exposure (e.g., age, calving or feeding areas);
Individual marine mammal responses (behavioral or
physiological) to acoustic stressors (acute, chronic, or cumulative),
other stressors, or cumulative impacts from multiple stressors;
How anticipated responses to stressors impact either: (1)
long-term fitness and survival of individual marine mammals; or (2)
populations, species, or stocks;
Effects on marine mammal habitat (e.g., marine mammal prey
species, acoustic habitat, or other important physical components of
marine mammal habitat); and,
Mitigation and monitoring effectiveness.
Visual Monitoring--Marine mammal monitoring during geotechnical
survey activities must be conducted by NMFS-approved PSOs in a manner
consistent with the following:
PSOs must be independent (i.e., not construction
personnel), and have no other assigned tasks during monitoring periods;
At least one PSO must have prior experience performing the
duties of a PSO during construction activity pursuant to a NMFS-issued
incidental take authorization;
Other PSOs may substitute other relevant experience,
education (degree in biological science or related field) or training
for experience performing the duties of a PSO during construction
activities pursuant to a NMFS-issued incidental take authorization;
Where a team of three or more PSOs is required, a lead
observer or monitoring coordinator will be designated. The lead
observer will be required to have prior experience working as a marine
mammal observer during construction activity pursuant to a NMFS-issued
incidental take authorization; and,
PSOs must be approved by NMFS prior to beginning any
activity subject to this IHA.
PSOs should also have the following additional qualifications:
Ability to conduct field observations and collect data
according to assigned protocols;
Experience or training in the field identification of
marine mammals, including identification of behaviors;
Sufficient training, orientation, or experience with the
construction operation to provide for personal safety during
observations;
Writing skills sufficient to prepare a report of
observations including, but not limited to, the number and species of
marine mammals observed; dates and times when in-water construction
activities were conducted; dates, times, and reason for implementation
of mitigation (or why mitigation was note implemented when required);
and marine mammal behavior; and,
Ability to communicate orally, by radio or in person, with
project personnel to provide real-time information on marine mammals
observed in the area as necessary.
Visual Monitoring of the Project Area--Visual monitoring of the
project area would be conducted by a minimum of two trained PSOs
positioned at suitable vantage points (see figure 3-2 in the Marine
Mammal Mitigation and Monitoring Plan). During all geotechnical
activities, at least two PSOs would be assigned to each active survey
location to monitor the shutdown zones and harassment zones. At least
one of these PSOs would observe from the cliffs adjacent to the project
site. When conducting geotechnical survey activities at offshore
locations, one of these PSOs would be placed on the barge.
Monitoring of the project area would be conducted 30 minutes
before, during, and 30 minutes after all in water construction
activities. In addition, PSOs will record all incidents of marine
mammal occurrence, regardless of distance from activity, and will
document any behavioral reactions in concert with distance from
geotechnical survey activities. Geotechnical survey activities include
the time to conduct LPT and borehole drilling, as long as the time
elapsed between uses of the geotechnical survey equipment is no more
than 30 minutes.
Visual Monitoring of North Rookery--To inform take estimates for
future construction activities, PSOs would also conduct daily morning
counts of hauled out pinnipeds at North Rookery, from the Northern
Point of north Rookery and following the rocky shoreline to the south,
during the project period and in the morning, prior to commencing work.
USACE would determine the site specific counting area each day based on
accessibility, any need to avoid seals above the cliffs, and visibility
below the cliffs. USACE would provide coordinates identifying the PSO
monitoring location and the start and end location of where counts are
conducted each day.
Reporting
USACE would submit a draft marine mammal monitoring report to NMFS
within 90 days after the completion of geotechnical survey activities,
or 60 days prior to a requested date of issuance of any future IHAs for
the project, or other projects at the same location, whichever comes
first. The
[[Page 11299]]
marine mammal monitoring report will include an overall description of
work completed, a narrative regarding marine mammal sightings during
all visual monitoring, and associated PSO data sheets. Specifically,
the report will include:
Dates and times (begin and end) of all marine mammal
monitoring;
Geotechnical survey activities occurring during each daily
observation period, including: (1) the number and type of survey
activities completed and the method (e.g., LPT or borehole drilling);
and, (2) total duration of driving time for each survey location
(borehole drilling) and number of strikes for each survey location
(LPT);
PSO locations during marine mammal monitoring;
Start and end location of monitoring area associated with
Visual Monitoring of North Rookery morning counts;
Environmental conditions during monitoring periods (at
beginning and end of PSO shift and whenever conditions change
significantly), including Beaufort sea state and any other relevant
weather conditions including cloud cover, fog, sun glare, and overall
visibility to the horizon, and estimated observable distance;
During all monitoring efforts, upon observation of a
marine mammal, the following information: (1) name of PSO who sighted
the animal(s) and PSO location and activity at time of sighting; (2)
time of sighting; (3) identification of the animal(s) (e.g., genus/
species, lowest possible taxonomic level, or unidentified), PSO
confidence in identification, and the composition of the group if there
is a mix of species; (4) distance and location of each observed marine
mammal relative to the survey location for each sighting; (5) estimated
number of animals (min/max/best estimate); (6) estimated number of
animals by cohort (adults, juveniles, neonates, group composition,
etc.);
During monitoring associated with geotechnical activities
only, the following information (1) animal's closest point of approach
and estimated time spent within the harassment zone; and, (2)
description of any marine mammal behavioral observations (e.g.,
observed behaviors such as feeding or traveling), including an
assessment of behavioral responses thought to have resulted from the
activity (e.g., no response or changes in behavioral state such as
ceasing feeding, changing direction, flushing, or breaching);
Number of marine mammals detected within the harassment
zones, by species; and,
Detailed information about implementation of any
mitigation (e.g., shutdowns and delays), a description of specific
actions that ensued, and resulting changes in behavior of the
animal(s), if any.
A final report must be prepared and submitted within 30 calendar
days following receipt of any NMFS comments on the draft report. If no
comments are received from NMFS within 30 calendar days of receipt of
the draft report, the report shall be considered final. All PSO data
would be submitted electronically in a format that can be queried, such
as a spreadsheet or database, and would be submitted with the draft
marine mammal report.
In the event that personnel involved in the geotechnical activities
discover an injured or dead marine mammal, the Holder must report the
incident to the Office of Protected Resources (OPR), NMFS
(PR.ITP.MonitoringReports@noaa.gov and itp.fleming@noaa.gov) and Alaska
Regional Stranding network (877-925-7773) as soon as feasible. If the
death or injury was clearly caused by the specified activity, the
Holder must immediately cease the activities until NMFS OPR is able to
review the circumstances of the incident and determine what, if any,
additional measures are appropriate to ensure compliance with the terms
of this IHA. The Holder must not resume their activities until notified
by NMFS. The report must include the following information:
Time, date, and location (latitude/longitude) of the first
discovery (and updated location information if known and applicable);
Species identification (if known) or description of the
animal(s) involved;
Condition of the animal(s) (including carcass condition if
the animal is dead);
Observed behaviors of the animal(s), if alive;
If available, photographs or video footage of the
animal(s); and,
General circumstances under which the animal was
discovered.
Negligible Impact Analysis and Determination
NMFS has defined negligible impact as an impact resulting from the
specified activity that cannot be reasonably expected to, and is not
reasonably likely to, adversely affect the species or stock through
effects on annual rates of recruitment or survival (50 CFR 216.103). A
negligible impact finding is based on the lack of likely adverse
effects on annual rates of recruitment or survival (i.e., population-
level effects). An estimate of the number of takes alone is not enough
information on which to base an impact determination. In addition to
considering estimates of the number of marine mammals that might be
``taken'' through harassment, NMFS considers other factors, such as the
likely nature of any impacts or responses (e.g., intensity, duration),
the context of any impacts or responses (e.g., critical reproductive
time or location, foraging impacts affecting energetics), as well as
effects on habitat, and the likely effectiveness of the mitigation. We
also assess the number, intensity, and context of estimated takes by
evaluating this information relative to population status. Consistent
with the 1989 preamble for NMFS' implementing regulations (54 FR 40338,
September 29, 1989), the impacts from other past and ongoing
anthropogenic activities are incorporated into this analysis via their
impacts on the baseline (e.g., as reflected in the regulatory status of
the species, population size and growth rate where known, ongoing
sources of human-caused mortality, or ambient noise levels).
To avoid repetition the majority of our analysis applies to all the
species listed in table 2, given that many of the anticipated effects
of this project on different marine mammal stocks are expected to be
relatively similar in nature. Where there are meaningful differences
between species or stocks, or groups of species, in anticipated
individual responses to activities, impact of expected take on the
population due to differences in population status, or impacts on
habitat, they are described independently in the analysis below.
Geotechnical surveys associated with the project, as outlined
previously, have the potential to disturb or displace marine mammals.
Specifically, the specified activities may result in take, in the form
of Level B and Level A harassment, from underwater sounds generated by
borehole drilling and LPT. Potential takes could occur if individuals
are present in the ensonified zone when these activities are underway.
Takes by Level B harassment would be due to potential behavioral
disturbance and TTS.
Takes by Level A harassment would be due to auditory injury. No
serious injury or mortality would be expected, even in the absence of
required mitigation measures, given the nature of the activities. The
potential for harassment would be further minimized through the
implementation of planned mitigation measures (see Proposed Mitigation
section). A low amount of
[[Page 11300]]
take by Level A harassment is expected for northern fur seal (n=35) to
account for the possibility that an animal would enter the Level A
harassment zone and remain within that zone for a duration long enough
to incur auditory injury before moving away. Any take by Level A
harassment of northern fur seal is expected to arise from, at most, a
small degree of PTS (i.e., minor degradation of hearing capabilities
within regions of hearing that align most completely with the energy
produced by LPT such as the low-frequency region below 2 kHz), not
severe hearing impairment or impairment within the ranges of greatest
hearing sensitivity. Animals would need to be exposed to higher levels
and/or longer duration than are expected to occur here in order to
incur any more than a small degree of PTS. Some subset of northern fur
seal or harbor seal that are behaviorally harassed could also
simultaneously incur some small degree of TTS for a short duration of
time. However, since the hearing sensitivity of individuals that incur
TTS is expected to recover completely within minutes to hours, it is
unlikely that the brief hearing impairment would affect the
individual's long-term ability to forage and communicate with
conspecifics, and would therefore not likely impact reproduction or
survival of any individual marine mammal, let alone adversely affect
rates of recruitment or survival of the species or stock. Likewise, due
to the small degree anticipated, any PTS potential would not be
expected to affect the reproductive success or survival of any
individuals, much less result in adverse impacts on the species or
stock.
Effects on individuals that are taken by Level B harassment in the
form of behavioral disruption, on the basis of reports in the
literature as well as monitoring from other similar activities, would
likely be limited to reactions such as avoidance, increased swimming
speeds, increased surfacing time, or decreased foraging (if such
activity were occurring) (e.g., Thorson and Reyff, 2006). Most likely,
individuals would simply move away from the sound source and
temporarily avoid the area where geotechnical surveys are occurring. If
sound produced by project activities is sufficiently disturbing,
animals are likely to simply avoid the area while the activities are
occurring. We expect that any avoidance of the project areas by marine
mammals would be temporary in nature and that any marine mammals that
avoid the project areas during geotechnical surveys would not be
permanently displaced. Indirect effects on marine mammal prey during
the geotechnical surveys are expected to be minor, and these effects
are unlikely to cause substantial effects on marine mammals at the
individual level. Given the time of year in which project activities
are planned, short-term avoidance of the project areas and energetic
impacts of interrupted foraging or other important behaviors is
unlikely to affect the reproduction or survival of individual marine
mammals, and the effects of behavioral disturbance on individuals is
not likely to accrue in a manner that would affect the rates of
recruitment or survival of any affected stock.
For harbor seal, take would occur within a limited, relatively
confined area of the stock's range, which is not of particular
importance for harbor seal that may occur there. Given the availability
of suitable habitat nearby, any displacement of marine mammals from the
project areas is not expected to affect marine mammals' fitness,
survival, and reproduction due to the limited geographic area that
would be affected in comparison to available habitat elsewhere on the
island. Additionally, NMFS anticipates that the prescribed mitigation
will minimize the duration and intensity of expected harassment events.
While the project site is located adjacent to the largest northern
fur seal rookery in the world, the exposure of northern fur seal to
sound from the proposed activities would be minimized by the time of
year the work is planned and required proposed mitigation measures
(e.g., shutdown zones). Beginning in April, adult males will land at a
number of sites where they begin to determine which site to establish
their breeding territory before the arrival of females in mid-June and
July. Non-breeding aged males will land and haul out along the rocky
shoreline adjacent to the Access Ramp labeled in figure 4-3 in the
USACE's application, while, territorial males will occupy and defend
prime breeding territories before females arrive in mid-June and July.
Pregnant females arrive around mid-June each year. They give birth just
days after arrival on land and then mate (NMFS, 2024). Pups are nursed
until weaning (about 4 months) and leave their breeding site before
their mothers to forage independently for the first time.
All in-water geotechnical survey activities would be conducted
between April 15 and June 15. The planned temporal work restriction is
established to ensure that project activities do not impact northern
fur seals during sensitive life stages (i.e., when pregnant and pupping
northern fur seals are present). The temporal work restriction would
also greatly reduce the overall number of takes of northern fur seal as
fewer northern fur seal are present in the spring compared to the
summer.
While the project site is adjacent to the largest northern fur seal
rookery in the world, the effects of the activities on marine mammal
habitat generally, such as sedimentation and impacts to the
availability of prey species, are expected to be limited both spatially
and temporally, constrained to the immediate area around each
geotechnical survey location and returning to baseline levels quickly.
Some fish may leave the area of disturbance, thus temporarily impacting
foraging opportunities for non-breeding male northern fur seals
(territorial males do not forage after establishing territories) and
harbor seal in a limited portion of the foraging range; but, because of
the short duration of the activities and the relatively small area of
the habitat that may be affected, the impacts to marine mammal habitat
are not expected to cause significant or long-term negative
consequences.
In addition, it is unlikely that minor noise effects in a small,
localized area of habitat would have any effect on each stock's ability
to recover. In combination, we believe that these factors, as well as
the available body of evidence from other similar activities,
demonstrate that the potential effects of the specified activities
would have only minor, short-term effects on individuals. The specified
activities are not expected to impact rates of recruitment or survival
and would therefore not result in population-level impacts.
In summary and as described above, the following factors primarily
support our preliminary determination that the impacts resulting from
this activity are not expected to adversely affect any of the species
or stocks through effects on annual rates of recruitment or survival:
No serious injury or mortality is anticipated or
authorized;
Level A harassment, for northern fur seal only, would be
very small amounts of a low degree;
Anticipated take by Level B harassment are relatively low
for all stocks;
Level B harassment would be primarily in the form of
behavioral disturbance, resulting in avoidance of the project areas
around where borehole drilling or LPT is occurring, with some low-level
TTS that may limit the detection of acoustic cues for relatively brief
amounts of time in relatively confined footprints of activities;
Effects on species that serve as prey for marine mammals
from the activities
[[Page 11301]]
are expected to be short-term and, therefore, any associated impacts on
marine mammal feeding are not expected to result in significant or
long-term consequences for individuals, or to accrue to adverse impacts
on their populations;
The ensonified areas are very small relative to the
overall habitat ranges of all species and stocks, and would not
adversely affect any areas of known biological importance;
The lack of anticipated significant or long-term negative
effects to marine mammal habitat; and,
USACE would implement mitigation measures including visual
monitoring, and shutdown zones to minimize the numbers of marine
mammals exposed to injurious levels of sound.
Based on the analysis contained herein of the likely effects of the
specified activity on marine mammals and their habitat, and taking into
consideration the implementation of the proposed monitoring and
mitigation measures, NMFS preliminarily finds that the total marine
mammal take from the proposed activity will have a negligible impact on
all affected marine mammal species or stocks.
Small Numbers
As noted previously, only take of small numbers of marine mammals
may be authorized under sections 101(a)(5)(A) and (D) of the MMPA for
specified activities other than military readiness activities. The MMPA
does not define small numbers and so, in practice, where estimated
numbers are available, NMFS compares the number of individuals taken to
the most appropriate estimation of abundance of the relevant species or
stock in our determination of whether an authorization is limited to
small numbers of marine mammals. When the predicted number of
individuals to be taken is fewer than one-third of the species or stock
abundance, the take is considered to be of small numbers. Additionally,
other qualitative factors may be considered in the analysis, such as
the temporal or spatial scale of the activities.
The amount of take NMFS proposed to authorize is below one-third of
the estimated stock abundance for all species, except for Pribilof
Island harbor seals (table 2).
The total number of takes proposed for authorization of harbor
seal, if assumed to accrue solely to new individuals of the Pribilof
Island stock, is >50 percent of the total stock abundance, which is
currently estimated as 229. However, these numbers represent the
estimated incidents of take, not the number of individuals taken. That
is, it is expected that a relatively small subset of these harbor seal
would be harassed by project activities, as harbor seal primarily occur
to the west on the far side of St. George Island. (Williams, 2024,
personal communication). Given that the specified activity will be
stationary within an area not recognized as any special significance
that would serve to attract or aggregate harbor seals we therefore
believe that the estimated numbers of takes, were they to occur, likely
represent repeated exposures of a much smaller number of harbor seals
and that these estimated incidents of take represent small numbers of
harbor seal.
Based on the analysis contained herein of the proposed activity
(including the proposed mitigation and monitoring measures) and the
anticipated take of marine mammals, NMFS preliminarily finds that small
numbers of marine mammals would be taken relative to the population
size of the affected species or stocks.
Unmitigable Adverse Impact Analysis and Determination
In order to issue an IHA, NMFS must find that the specified
activity will not have an ``unmitigable adverse impact'' on the
subsistence uses of the affected marine mammal species or stocks by
Alaskan Natives. NMFS has defined ``unmitigable adverse impact'' in 50
CFR 216.103 as an impact resulting from the specified activity: (1)
That is likely to reduce the availability of the species to a level
insufficient for a harvest to meet subsistence needs by: (i) Causing
the marine mammals to abandon or avoid hunting areas; (ii) Directly
displacing subsistence users; or (iii) Placing physical barriers
between the marine mammals and the subsistence hunters; and (2) That
cannot be sufficiently mitigated by other measures to increase the
availability of marine mammals to allow subsistence needs to be met.
Alaska Natives on St. George Island harvest subsistence resources,
including northern fur seal, harbor seal, and Steller sea lion.
Pribilovians on St. George Island may harvest up to a total of 500 male
fur seals each year over the course of both the sub-adult harvest and
the male young of the year harvest (50 CFR 216.72), On St. George
Island, the open season for male sub-adult fur seal harvest runs from
June 23 through August 8 annually, while the male young of the year fur
seal open season spans from September 16 through November 30 annually.
The most recent monitoring report available indicates that only 10 male
sub-adult fur seal and 6 male young of the year fur seal were harvested
in 2023 (Kashevarof, 2023a; Kashevarof, 2023b). There are no formal
seasons for harbor seals or Steller sea lion, but historically they are
spring, winter, and fall (Williams, 2025, personal communication).
USACE contacted Mark Merculief, the mayor St. George, Alaska, and
described him as a subsistence hunter who personally knows every
subsistence hunter in St. George community. Mayor Merculief indicated
that in recent years there have been no subsistence efforts for marine
mammals during the planned project period.
The proposed project is not likely to adversely impact the
availability of any marine mammal species or stocks that are commonly
used for subsistence purposes or impact subsistence harvest of marine
mammals in the region because:
Geotechnical surveys are planned to be conducted prior to
the opening of subsistence hunting for northern fur seal and during a
time when other pinnipeds have not been subsistence harvested in recent
years;
Geotechnical surveys are temporary and localized to
between the Old Jetty and North Rookery;
Mitigation measures will be implemented to avoid
disturbance of Steller sea lion in the area and minimize disturbance of
harbor seal and northern fur seal;
The project is not expected to result in significant
changes to availability of subsistence resources.
Based on the description of the specified activity, the measures
described to minimize adverse effects on the availability of marine
mammals for subsistence purposes, and the proposed mitigation and
monitoring measures, NMFS has preliminarily determined that there will
not be an unmitigable adverse impact on subsistence uses from USACE's
proposed activities.
Endangered Species Act
Section 7(a)(2) of the ESA of 1973 (16 U.S.C. 1531 et seq.)
requires that each Federal agency insure that any action it authorizes,
funds, or carries out is not likely to jeopardize the continued
existence of any endangered or threatened species or result in the
destruction or adverse modification of designated critical habitat. To
ensure ESA compliance for the issuance of IHAs, NMFS consults
internally whenever we propose to authorize take for endangered or
threatened species.
No incidental take of ESA-listed species is proposed for
authorization or
[[Page 11302]]
expected to result from this activity. Therefore, NMFS has determined
that formal consultation under section 7 of the ESA is not required for
this action.
Proposed Authorization
As a result of these preliminary determinations, NMFS proposes to
issue an IHA to USACE for conducting geotechnical survey activities in
St. George, Alaska between April 15, 2025 and June 15, 2025, provided
the previously mentioned mitigation, monitoring, and reporting
requirements are incorporated. A draft of the proposed IHA can be found
at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities.
Request for Public Comments
We request comment on our analyses, the proposed authorization, and
any other aspect of this notice of proposed IHA for the proposed
geotechnical survey activities. We also request comment on the
potential renewal of this proposed IHA as described in the paragraph
below. Please include with your comments any supporting data or
literature citations to help inform decisions on the request for this
IHA or a subsequent renewal IHA.
On a case-by-case basis, NMFS may issue a one-time, 1-year renewal
IHA following notice to the public providing an additional 15 days for
public comments when (1) up to another year of identical or nearly
identical activities as described in the Description of Proposed
Activity section of this notice is planned or (2) the activities as
described in the Description of Proposed Activity section of this
notice would not be completed by the time the IHA expires and a renewal
would allow for completion of the activities beyond that described in
the Dates and Duration section of this notice, provided all of the
following conditions are met:
A request for renewal is received no later than 60 days
prior to the needed renewal IHA effective date (recognizing that the
renewal IHA expiration date cannot extend beyond 1 year from expiration
of the initial IHA);
The request for renewal must include the following:
(1) An explanation that the activities to be conducted under the
requested renewal IHA are identical to the activities analyzed under
the initial IHA, are a subset of the activities, or include changes so
minor (e.g., reduction in pile size) that the changes do not affect the
previous analyses, mitigation and monitoring requirements, or take
estimates (with the exception of reducing the type or amount of take);
and
(2) A preliminary monitoring report showing the results of the
required monitoring to date and an explanation showing that the
monitoring results do not indicate impacts of a scale or nature not
previously analyzed or authorized; and
Upon review of the request for renewal, the status of the
affected species or stocks, and any other pertinent information, NMFS
determines that there are no more than minor changes in the activities,
the mitigation and monitoring measures will remain the same and
appropriate, and the findings in the initial IHA remain valid.
Dated: February 28, 2025.
Kimberly Damon-Randall,
Director, Office of Protected Resources, National Marine Fisheries
Service.
[FR Doc. 2025-03543 Filed 3-4-25; 8:45 am]
BILLING CODE 3510-22-P