Notice2023-25934
Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to the U.S. Army Corps of Engineers Unalaska (Dutch Harbor) Channel Deepening Project
Primary source
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Published
November 24, 2023
Effective
January 1, 2024
Issuing agencies
Commerce DepartmentNational Oceanic and Atmospheric Administration
Abstract
In accordance with the regulations implementing the Marine Mammal Protection Act (MMPA) as amended, notification is hereby given that NMFS has issued an incidental harassment authorization (IHA) to the United States Army Corps of Engineers (Alaska District) (USACE) for authorization to take marine mammals incidental to Unalaska (Dutch Harbor) Channel Deepening in Iliuliuk Bay, Unalaska, Alaska.
Full Text
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<title>Federal Register, Volume 88 Issue 225 (Friday, November 24, 2023)</title>
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[Federal Register Volume 88, Number 225 (Friday, November 24, 2023)]
[Notices]
[Pages 82326-82336]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2023-25934]
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DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
[RTID 0648-XC980]
Takes of Marine Mammals Incidental to Specified Activities;
Taking Marine Mammals Incidental to the U.S. Army Corps of Engineers
Unalaska (Dutch Harbor) Channel Deepening Project
AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and
Atmospheric Administration (NOAA), Commerce.
ACTION: Notice; issuance of an incidental harassment authorization.
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SUMMARY: In accordance with the regulations implementing the Marine
Mammal Protection Act (MMPA) as amended, notification is hereby given
that NMFS has issued an incidental harassment authorization (IHA) to
the United States Army Corps of Engineers (Alaska District) (USACE) for
authorization to take marine mammals incidental to Unalaska (Dutch
Harbor) Channel Deepening in Iliuliuk Bay, Unalaska, Alaska.
DATES: This Authorization is effective from January 1, 2024 through
December 31, 2024.
ADDRESSES: Electronic copies of the application and supporting
documents, as well as a list of the references cited in this document,
may be obtained online at <a href="https://www.fisheries.noaa.gov/action/incidental-take-authorization-us-army-corps-engineers-unalaska-dutch-harbor-channel">https://www.fisheries.noaa.gov/action/incidental-take-authorization-us-army-corps-engineers-unalaska-dutch-harbor-channel</a>. In case of problems accessing these documents, please
call the contact listed below.
FOR FURTHER INFORMATION CONTACT: Cara Hotchkin, 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 mitigation,
monitoring and reporting of the takings are set forth. The definitions
of all applicable MMPA statutory terms cited above are included in the
relevant sections below.
Summary of Request
On October 31, 2022, NMFS received a request from the United States
Army Corps of Engineers--Alaska District (USACE) for an IHA to take
marine mammals incidental to deepening the entrance to Iliuliuk Bay,
adjacent to Dutch Harbor, Alaska. Following NMFS' review of the
application, USACE submitted supplemental information on November 28,
2022 and January 5, 2023. The application was deemed adequate and
complete on March 2, 2023. The notice of the proposed IHA and request
for comments was published on April 11, 2023 (88 FR 21630). USACE's
request is for take of harbor seals (Phoca vitulina richardsi), Steller
sea lions (Eumetopias jubatus), harbor porpoise (Phocoena phocoena),
and humpback whales (Megaptera novaengliae) by Level A harassment and
Level B Harassment. Neither USACE nor NMFS expect serious injury or
mortality to result from this activity and, therefore, an IHA is
appropriate.
Description of the Specified Activity
The USACE plans to deepen the entrance channel of Iliuliuk Bay by
means of dredging and (if necessary) confined blasting of a 42-foot
(ft) (12.8 meter (m)) deep ``bar'' which currently restricts access to
the port of Dutch Harbor, Alaska. Dutch Harbor is the only deep draft,
year-round ice-free port along the 1,200-mile (1,931 km) Aleutian
Island chain, providing vital services to vessels operating in both the
North Pacific and the Bering Sea, and the depth of the bar currently
restricts access for large vessels that may need to enter the port,
particularly during extreme weather. The purpose of the project is to
increase navigational safety and improve economic efficiencies into and
out of Dutch Harbor via Iliuliuk Bay.
Removal of the bar will involve dredging (via clamshell dredge or
long-reach excavator) an area approximately 600 ft (182.9 m) by 600 ft
(182.9 m), moving approximately 182,000 cubic yards (139,150 cubic
meters) of sediment. Dredged material will be placed in the water
immediately adjacent to the inside of the bar in approximately 100 ft
(33.3 m) of water. If required to enable dredging, confined blasting
(hereafter ``blasting'') involving drilled boreholes and multiple
charges with microdelays between blasts will be used to break up the
sediment.
Safety restrictions impose some limits on blasting activity and
potential mitigations available to protect marine mammals. The
explosives cannot ``sleep'' after being placed for longer than 24 hours
without becoming a risk to private property and human health, and they
cannot be detonated in the dark. If a marine mammal enters the blast
area following the emplacement of charges, detonation will be delayed
as long as possible. All other legal measures to avoid injury will be
utilized; however, the charges will be detonated when delay is no
longer feasible. As discussed in the mitigation section, in order to
minimize the chances the charges need to be detonated while animals are
present in the vicinity, the IHA includes a mitigation measure
requiring explosives to be set as early in the day as possible, and
detonated as soon as the pre-clearance zone is clear for 30 minutes.
Sounds resulting from confined blasting may result in the
incidental take of marine mammals by Level A and Level B harassment in
the form of slight injury (auditory and non-auditory) and behavioral
harassment. Dredging and disposal of dredged material are not expected
to result in either Level A or Level B harassment due to the low source
level and mid-channel location of the dredging activities. If dredging
is sufficient to deepen the channel to the required depth, reduced or
no blasting may be necessary. The notice for the proposed IHA (88 FR
21630, April 11, 2023) analyzed a conservative scenario requiring
blasting approximately 50 percent of the bar area, resulting in
[[Page 82327]]
approximately 1,800 drilled boreholes and up to 24 total blasting
events.
A detailed description of the planned project is provided in the
Federal Register notice for the proposed IHA (88 FR 21630, April 11,
2023). Since that time, no changes have been made to the planned
activities. Therefore, a detailed description is not provided here.
Please refer to that Federal Register notice for the detailed
description of the specific activity.
Comments and Responses
A notice of NMFS' proposal to issue an IHA to the USACE was
published in the Federal Register on April 11, 2023 (88 FR 21630). That
notice described, in detail, USACE's planned activities, the marine
mammal species that may be affected by the activities, and the
anticipated effects on marine mammals. In that notice, we requested
public input on the request for authorization described therein, our
analyses, the proposed authorization, and any other aspect of the
notice of proposed IHA, and requested that interested persons submit
relevant information, suggestions, and comments. This proposed notice
was available for a 30-day public comment period.
NMFS received two non-substantive comments on the proposed IHA: one
from the U.S. Geological Survey stating no objections to the project,
and one from a private citizen opposed to offshore wind, which is not
related to this action.
Changes From the Proposed IHA to Final IHA
Since the Federal Register notice of the proposed IHA was published
(88 FR 21630, April 11, 2023), NMFS published the final 2022 Alaska and
Pacific Stock Assessment Reports (SARs), which describe revised stock
structures under the MMPA for humpback whales. In the notice of
proposed IHA, we explained that although we typically consider updated
peer-reviewed data provided in draft SARs to be the best available
science, and use the information accordingly, we make exception for
proposed revised stock structures. Upon finalization of these revised
stock structures, we have made appropriate updates, including
description of the potentially affected stocks (see table 1),
attribution of take numbers to stock (see Estimated Take), and by
updating our analyses to ensure the necessary determinations are made
for the new stocks (see Negligible Impact Analysis and Determination
and Small Numbers).
Additionally, between the publication of the proposed IHA (88 FR
21630, April 11, 2023) and this notice, the USACE requested that the
effective dates of the authorization be shifted from November 1, 2023
through October 31, 2024 to January 1, 2024 through December 31, 2024
due to logistical constraints. The analysis presented in the proposed
IHA remains valid because the estimated takes were based on year-round
monitoring data at the project location. The change to the effective
dates of the authorization is reflected in the Dates section, above.
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, incorporated here by reference, instead of
reprinting the information. Additional information regarding population
trends and threats may be found in NMFS' Stock Assessment Reports
(SARs; <a href="http://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments">www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments</a>) and more general information about these
species (e.g., physical and behavioral descriptions) may be found on
NMFS' website (<a href="https://www.fisheries.noaa.gov/find-species">https://www.fisheries.noaa.gov/find-species</a>).
Table 1 lists all species or stocks for which take is expected and
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 authorized here, PBR and
annual serious injury and mortality 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 and Pacific Ocean SARs. All values presented in table
1 are the most recent available at the time of publication and are
available online at: <a href="http://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments">www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments</a>.
Table 1--Species Likely Impacted by the Specified Activities \1\
----------------------------------------------------------------------------------------------------------------
Stock abundance
ESA/MMPA (CV, Nmin, most Annual
Common name Scientific name Stock status; recent abundance PBR M/SI
strategic survey) \3\ \4\
(Y/N) \2\
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Order Artiodactyla--Infraorder Cetacea--Mysticeti (baleen whales)
----------------------------------------------------------------------------------------------------------------
Family Balaenopteridae
(rorquals):
Humpback Whale \5\....... Megaptera Hawai[revaps]i.. -, -, N 11,278 (0.56, 127 27.09
novaeangliae. Mexico--North T, D, Y 7,265, 2020). UND 0.57
Pacific. E, D, Y 918 (0.217, UNK, 3.4 5.82
Western North 2006).
Pacific. 1,084 (0.088,
1,007, 2021).
----------------------------------------------------------------------------------------------------------------
Odontoceti (toothed whales, dolphins, and porpoises)
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Family Phocoenidae
(porpoises):
Harbor porpoise.......... Phocoena Bering Sea \5\.. -, -, Y UNK (UNK, N/A, UND 0.4
phocoena. Gulf of Alaska.. -, -, Y 2008). UND 72
31,046 (0.21, N/
A, 1998).
----------------------------------------------------------------------------------------------------------------
[[Page 82328]]
Order Carnivora--Pinnipedia
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Family Otariidae (eared seals
and sea lions):
Steller Sea Lion......... Eumetopias Western......... E, D, Y 52,932 (N/A, 318 254
jubatus. Eastern......... -, -, N 52,932, 2019). 2592 112
43,201 (N/A,
43,201, 2017).
Family Phocidae (earless
seals):
Harbor Seal.............. Phoca vitulina.. Aleutian Islands -, -, N 5,588 (N/A, 97 90
5,366, 2018).
----------------------------------------------------------------------------------------------------------------
\1\ Information on the classification of marine mammal species can be found on the web page for The Society for
Marine Mammalogy's Committee on Taxonomy (<a href="https://marinemammalscience.org/science-and-publications/list-marine-mammal-species-subspecies/">https://marinemammalscience.org/science-and-publications/list-marine-mammal-species-subspecies/</a>; Committee on Taxonomy (2022)).
\2\ Endangered Species Act (ESA) status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-)
indicates that the species is not listed under the ESA or designated as depleted under the MMPA. Under the
MMPA, a strategic stock is one for which the level of direct human-caused mortality exceeds PBR or which is
determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or
stock listed under the ESA is automatically designated under the MMPA as depleted and as a strategic stock.
\3\ NMFS marine mammal stock assessment reports online at: <a href="http://www.nmfs.noaa.gov/pr/sars/">www.nmfs.noaa.gov/pr/sars/</a>. CV is coefficient of
variation; Nmin is the minimum estimate of stock abundance. In some cases, CV is not applicable due to lack of
recent surveys allowing for accurate assessment 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. A CV associated with estimated mortality
due to commercial fisheries is presented in some cases.
\5\ The best available abundance estimate and Nmin are likely an underestimate for the entire stock because it
is based upon a survey that covered only a small portion of the stock's range. PBR for this stock is
undetermined due to this estimate being older than 8 years.
A detailed description of the of the species likely to be affected
by the Unalaska Channel Deepening project, including brief
introductions to the species and relevant stocks as well as available
information regarding population trends and threats, and information
regarding local occurrence, were provided in the Federal Register
notice for the proposed IHA (88 FR 21630, April 11, 2023); since that
time, we are not aware of any changes in the status of these species
and stocks; therefore, detailed descriptions are not provided here.
Please refer to that Federal Register notice for these descriptions.
Please also refer to NMFS' website (<a href="https://www.fisheries.noaa.gov/find-species">https://www.fisheries.noaa.gov/find-species</a>) for generalized species accounts.
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.). Note that no direct measurements of
hearing ability have been successfully completed for mysticetes (i.e.,
low-frequency cetaceans). Subsequently, NMFS (2018) described
generalized hearing ranges for these marine mammal hearing groups.
Generalized hearing ranges were chosen based on the approximately 65
decibel (dB) threshold from the normalized composite audiograms, with
the exception for lower limits for low-frequency cetaceans where the
lower bound was deemed to be biologically implausible and the lower
bound from Southall et al. (2007) retained. Marine mammal hearing
groups and their associated hearing ranges are provided in table 2.
Table 2--Marine Mammal Hearing Groups
[NMFS, 2018]
------------------------------------------------------------------------
Hearing group Generalized hearing range *
------------------------------------------------------------------------
Low-frequency (LF) cetaceans (baleen 7 Hz to 35 kHz.
whales).
Mid-frequency (MF) cetaceans 150 Hz to 160 kHz.
(dolphins, toothed whales, beaked
whales, bottlenose whales).
High-frequency (HF) cetaceans (true 275 Hz to 160 kHz.
porpoises, Kogia, river dolphins,
Cephalorhynchid, Lagenorhynchus
cruciger & L. australis).
Phocid pinnipeds (PW) (underwater) 50 Hz to 86 kHz.
(true seals).
Otariid pinnipeds (OW) (underwater) 60 Hz to 39 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 are typically not as broad. Generalized
hearing range chosen based on ~65 dB threshold from normalized
composite audiogram, with the exception for lower limits for LF
cetaceans (Southall et al., 2007) and PW pinniped (approximation).
The pinniped functional hearing group was modified from Southall et
al. (2007) on the basis of data indicating that phocid species have
consistently demonstrated an extended frequency range of hearing
compared to otariids, especially in the higher frequency range
(Hemil[auml] et al., 2006; Kastelein et al., 2009; Reichmuth et al.,
2013).
For more detail concerning these groups and associated frequency
ranges, please see NMFS (2018) for a review of available information.
Potential Effects of Specified Activities on Marine Mammals and Their
Habitat
The effects of underwater noise from USACE's construction
activities have the potential to result in behavioral harassment of
marine mammals in the vicinity of the blasting area. The notice
[[Page 82329]]
of proposed IHA (88 FR 21630, April 11, 2023) included a discussion of
the effects of anthropogenic noise on marine mammals and the potential
effects of underwater noise from confined blasting activities on marine
mammals and their habitat. That information and analysis is
incorporated by reference into this final IHA determination and is not
repeated here; please refer to the notice of proposed IHA (88 FR 21630,
April 11, 2023).
Estimated Take of Marine Mammals
This section provides an estimate of the number of incidental takes
authorized through this IHA, which informs both NMFS' consideration of
``small numbers,'' and the negligible impact determinations.
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 the explosive source (i.e., confined blasting) has the potential to
result in disruption of behavioral patterns for individual marine
mammals. There is also some potential for auditory injury and tissue
damage (Level A harassment) to result, primarily for cetaceans
(humpback whale and harbor porpoise) and phocids because predicted
auditory injury zones are larger than for otariids. The 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 authorized for this activity. While blasting has the
potential to result in mortality, when the isopleths within which
mortality could occur were calculated, the zones were sufficiently
small that the risk of mortality is considered discountable. Below we
describe how the take numbers were estimated.
For acoustic impacts, generally speaking, we estimate take by
considering: (1) acoustic thresholds above which NMFS believes the best
available science indicates marine mammals will be behaviorally
harassed or incur some degree of permanent hearing impairment; (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 take estimates.
Acoustic Thresholds
NMFS recommends the use of acoustic thresholds 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 PTS of some degree (equated to Level A
harassment). Thresholds have also been developed to identify the
pressure levels above which animals may incur different types of tissue
damage (non-acoustic Level A harassment or mortality) from exposure to
pressure waves from explosive detonation.
Level A harassment--NMFS' Technical Guidance for Assessing the
Effects of Anthropogenic Sound on Marine Mammal Hearing (Version 2.0)
(Technical Guidance, 2018) identifies dual criteria to assess auditory
injury (Level A harassment) to five different marine mammal groups
(based on hearing sensitivity) as a result of exposure to noise from
two different types of sources (impulsive (including explosives) or
non-impulsive). These thresholds are provided in table 3, below. The
references, analysis, and methodology used in the development of the
thresholds are described in NMFS' 2018 Technical Guidance, which may be
accessed at: <a href="http://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance">www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance</a>.
Explosive sources--Based on the best available science, NMFS uses
the acoustic and pressure thresholds indicated in tables 3 and 4 to
predict the onset of behavioral harassment, PTS, TTS, tissue damage,
and mortality.
For explosive activities using single detonations (i.e., no more
than one detonation within a day), such as those described in the
planned activity, NMFS uses TTS onset thresholds to assess the
likelihood of behavioral harassment, rather than the Level B Harassment
threshold for multiple detonations indicated in table 3. While marine
mammals may also respond behaviorally to single explosive detonations,
these responses are expected to typically be in the form of a startle
reaction, rather than a more meaningful disruption of a behavioral
pattern. On the rare occasion that a single detonation might result in
a behavioral disturbance that qualifies as Level B harassment, it would
be expected to be in response to a comparatively higher received level.
Accordingly, NMFS considers the potential for these responses to be
quantitatively accounted for through the application of the TTS
threshold, which, as noted above, is 5 dB higher than the behavioral
harassment threshold for multiple explosives.
Table 3--Explosive Thresholds for Marine Mammals for PTS, TTS, and Behavior
[Multiple detonations]
----------------------------------------------------------------------------------------------------------------
PTS impulsive TTS impulsive Behavioral threshold (multiple
Hearing group thresholds thresholds detonations)
----------------------------------------------------------------------------------------------------------------
Low-Frequency (LF) Cetaceans.... Cell 1: Lp,0- Cell 2: Lp,0- Cell 3: LE,LF,24h: 163 dB.
pk,flat: 219 dB; pk,flat: 213 dB;
LE,LF,24h: 183 dB. LE,LF,24h: 168 dB.
Mid-Frequency (MF) Cetaceans.... Cell 4: Lp,0- Cell 5: Lp,0- Cell 6: LE,MF,24h: 165 dB.
pk,flat: 230 dB; pk,flat: 224 dB;
LE,MF,24h: 185 dB. LE,MF,24h: 170 dB.
High-Frequency (HF) Cetaceans... Cell 7: Lp,0- Cell 8: Lp,0- Cell 9: LE,HF,24h: 135 dB.
pk,flat: 202 dB; pk,flat: 196 dB;
LE,HF,24h: 155 dB. LE,HF,24h: 140 dB.
Phocid Pinnipeds (PW) Cell 10: Lp,0- Cell 11: Lp,0- Cell 12: LE,PW,24h: 165 dB.
(Underwater). pk,flat: 218 dB; pk,flat: 212 dB;
LE,PW,24h: 185 dB. LE,PW,24h: 170 dB.
[[Page 82330]]
Otariid Pinnipeds (OW) Cell 13: Lp,0- Cell 14: Lp,0- Cell 15: LE,OW,24h: 183 dB.
(Underwater). pk,flat: 232 dB; pk,flat: 226 dB;
LE,OW,24h: 203 dB. LE,OW,24h: 188 dB.
----------------------------------------------------------------------------------------------------------------
* Dual metric acoustic thresholds for impulsive sounds: Use whichever results in the largest isopleth for
calculating PTS/TTS onset.
Note: Peak sound pressure (Lpk) has a reference value of 1 [micro]Pa, and cumulative sound exposure level (LE)
has a reference value of 1[micro]Pa\2\s. In this table, thresholds are abbreviated to reflect American
National Standards Institute standards (ANSI 2013). However, ANSI defines peak sound pressure as incorporating
frequency weighting, which is not the intent for this Technical Guidance. Hence, the subscript ``flat'' is
being included to indicate peak sound pressure should be flat weighted or unweighted within the overall marine
mammal generalized hearing range. The subscript associated with cumulative sound exposure level thresholds
indicates the designated marine mammal auditory weighting function (LF, MF, and HF cetaceans, and PW and OW
pinnipeds) and that the recommended accumulation period is 24 hours. The cumulative sound exposure level
thresholds 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 acoustic
thresholds will be exceeded.
Table 4--Lung and GI Tract Injury Thresholds for Underwater Explosives
----------------------------------------------------------------------------------------------------------------
Mortality (severe lung
Hearing group injury) * Slight lung injury * GI tract injury
----------------------------------------------------------------------------------------------------------------
All Marine Mammals................... Cell 1: Modified Cell 2: Modified Cell 3: Lp,0-pk,flat:
Goertner model; Goertner model; 237 dB.
Equation 1. Equation 2.
----------------------------------------------------------------------------------------------------------------
* Lung injury (severe and slight) thresholds are dependent on animal mass (Recommendation: table C.9 from DON
2017 based on adult and/or calf/pup mass by species).
Note: Peak sound pressure (Lpk) has a reference value of 1 [micro]Pa. In this table, thresholds are abbreviated
to reflect American National Standards Institute standards (ANSI 2013). However, ANSI defines peak sound
pressure as incorporating frequency weighting, which is not the intent for this Technical Guidance. Hence, the
subscript ``flat'' is being included to indicate peak sound pressure should be flat weighted or unweighted
within the overall marine mammal generalized hearing range.
Modified Goertner Equations for severe and slight lung injury (pascal-second).
Equation 1: 103M1/3(1 + D/10.1)1/6 Pa-s.
Equation 2: 47.5M1/3(1 + D/10.1)1/6 Pa-s.
M animal (adult and/or calf/pup) mass (kg) (table C.9 in DoN 2017).
D animal depth (meters).
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.
NMFS computed cumulative sound exposure impact zones from the
blasting information provided by the USACE. Peak source levels of the
confined blasts were calculated based on Hempen et al. (2007), and
scaled using a distance of 10 ft (3 m) and a weight of 95 lbs (43.1 kg)
for a single charge. The total charge weight is defined as the product
of the single charge weight and the number of charges. In this case,
the number of charges is 75. Explosive energy was then computed from
peak pressure of the single maximum charge, using the pressure and time
relationship of a shock wave (Urick, 1983). Due to time and spatial
separation of each single charge by a distance of 10 ft (3m), the
accumulation of acoustic energy is added sequentially, assuming the
transmission loss follows cylindrical spreading within the matrix of
charges. The sound exposure level (SEL) from each charge at its source
can then be calculated, followed by the received SEL from each charge.
Since the charges will be deployed in a grid of 10 ft (3 m) by 10 ft (3
m) apart, the received SELs from different charges to a given point
will vary depending on the distance of the charges from the receiver.
Without specific information regarding the layout of the charges, the
modeling assumes a grid of 8 by 9 charges with an additional three
charges located in three peripheral locations. Among the various total
SELs calculated (one at a receiver location corresponding to each
perimeter charge), the largest value, SELtotal (max) is selected to
calculate the impact range. Using the pressure versus time relationship
above, the frequency spectrum of the explosion can be computed by
taking the Fourier transform of the pressure (Weston, 1960), and
subsequently be used to produce hearing range weighted metrics.
Frequency specific transmission loss of acoustic energy due to
absorption is computed using the absorption coefficient, [alpha] (dB/
km), summarized by Fran[ccedil]ois and Garrison (1982a, b). Seawater
properties for computing sound speed and absorption coefficient were
based on NMFS Alaska Fisheries Science Center report of mean
measurements in Auke Bay (Sturdevant and Landingham, 1993) and the 2022
average seawater temperature from Unalaska (NOAA, 2023). Transmission
loss was calculated using the sonar equation:
TL = SEL<INF>total(m)</INF>-SEL<INF>threshold</INF>
where SEL<INF>threshold</INF> is the Level A harassment threshold. The
distances, R, where such transmission loss is achieved were computed
numerically by combining both geometric transmission loss, and
transmission loss due to frequency-specific absorption. A spreading
coefficient of 20 is assumed to account for acoustic energy loss from
the sediment into the water column. The outputs from this model are
summarized in table 5, below.
[[Page 82331]]
Table 5--Model Results of Impact Zones for Blasting in Meters (m)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Slight lung
Species Mortality injury GI tract PTS: SELcum PTS: SPLpk TTS: SELcum TTS: SPLpk
--------------------------------------------------------------------------------------------------------------------------------------------------------
Low frequency cetacean....................................... 4.0 9.2 25.8 * 344.66 205.29 * 1,918 409.62
High frequency cetacean...................................... 20.3 47.5 25.8 1,213.79 * 1,453.37 * 4,435.57 2,899.86
Otariid...................................................... 13.8 32.3 25.8 40.00 * 91.92 * 249.76 183.40
Phocid....................................................... 18.2 42.5 25.8 164.84 * 230.34 * 909.10 459.60
--------------------------------------------------------------------------------------------------------------------------------------------------------
* For the dual criteria of SELcum and SPLpk, the largest of the two calculated distances for each species group was used in our analysis. The PTS and
TTS distances for Steller sea lions resulting from the model seemed uncharacteristically small when compared to the other thresholds resulting from
the model and were doubled to 92 m and 230 m respectively for take estimation, mitigation, and monitoring.
Marine Mammal Occurrence
In this section, we provide information about the occurrence of
marine mammals, including density or other relevant information that
informed the take calculations. Reliable densities are not available
for Iliuliuk Bay, and generalized densities for the North Pacific are
not applicable given the high variability in occurrence and density at
specific areas around the Aleutian Island chain. Therefore, the USACE
consulted previous survey data in and around Iliuliuk Bay and Dutch
Harbor to arrive at a number of animals expected to occur within the
project area per day. Figure 4-8 and table 4-3 in the IHA application
provide further detail on observations of humpback whales, Steller sea
lions, and harbor seals in and around Iliuliuk Bay. Harbor porpoise
were not addressed in the IHA application; however, NMFS has authorized
takes of harbor porpoise take out of an abundance of caution, based on
the 2017 sighting of porpoises in the action area by USACE biologists.
Take Estimation
Here we describe how the information provided above is synthesized
to produce a quantitative estimate of the take that is reasonably
likely to occur.
Since reliable densities are not available, the USACE requested
take based on the maximum number of animals that may occur in the
blasting area per day multiplied by the number of days of the activity.
The applicant varied these calculations based on certain factors.
Because of the nature of the planned blasting (i.e., no more than one
blasting event per day), the behavioral thresholds associated with the
activity are the same as for the onset of TTS for all species. Both
behavioral disturbance and TTS may occur.
Humpback whale--Humpback whales are commonly sighted outside the
mouth of Iliuliuk Bay, and were most common in August and September
between 2 and 8 km from the survey site outside the mouth of the bay.
Humpbacks were also spotted within Iliuliuk Bay in much lower numbers
(maximum daily sightings within the bay: 4; outside the bay: 47) (USACE
2022). Based on the previous monitoring efforts in and around Iliuliuk
Bay, USACE and NMFS estimated that a maximum of two animals may be
present within the Level B harassment threshold for each blasting
event. While NMFS expects that the monitoring and mitigation described
later in this document will be effective at preventing injurious take
of marine mammals, we recognize that humpback whales are common in the
area, that animals may enter the blasting area after charges have been
set, and that there is a limit on the amount of time detonation may be
safely delayed. Humpback whales are highly visible, and their presence
would likely be known before charges are laid on a blasting day. We
therefore conservatively estimate up to 10 percent of the blasting
events may include a humpback whale within the Level A harassment
isopleth. With a maximum take of 2 animals per day, multiplied by a
maximum of 24 days of blasting, we have authorized up to 48 takes by
Level B harassment and up to 3 takes by Level A harassment of humpback
whales.
Harbor porpoise--Harbor porpoise were not included in the IHA
application. This species typically travels alone or in pairs, but may
occasionally be sighted in larger groups. Based on the USACE's
observation of a group of eight individuals in the project area in
2017, and other infrequent sightings of harbor porpoise in and around
Iliulliuk Bay, NMFS conservatively estimated that two animals may occur
within the Level B harassment threshold on up to 25 percent of blasting
days. Out of an abundance of caution, and because this species is both
very sensitive to noise (meaning the Level A harassment zone is
comparatively larger), including explosions (von Benda-Beckmann et al.,
2015), and difficult to see in the field, NMFS also proposed that up to
two harbor porpoise could be within the Level A harassment threshold
for up to 10 percent of the blasting events. Given 24 days of blasting,
we have authorized up to 12 harbor porpoise takes by Level B
harassment, and up to 5 harbor porpoise takes by Level A harassment
over the course of the activity.
Steller sea lion--During previous monitoring efforts, Steller sea
lions were sighted most frequently inside of Iliuliuk Bay, within 4 km
of the project area. The maximum number of sightings in a single day
was 32, though it is unclear whether this includes multiple sightings
of the same large group of 10 to 12 individuals (USACE 2022). Steller
sea lions in this area are known to congregate around and follow
fishing vessels that regularly transit into and out of Dutch Harbor.
Given the previous monitoring data, USACE and NMFS conservatively
estimated that a maximum of two animals may be within the Level B
harassment threshold for each blast. While NMFS expects that the
monitoring and mitigation described later in this document will be
effective at preventing injurious take of marine mammals, we recognize
that Steller sea lions are common in the area, that animals may enter
the blasting area after charges have been set, and that there is a
limit on the amount of time detonation may be safely delayed. Steller
sea lions may be difficult for observers to detect before charges are
laid on a blasting day, and we therefore conservatively estimated up to
two Steller sea lions may be within the Level A harassment isopleth for
up to 20 percent of the blasting events. With a maximum take of 2
animals per day, multiplied by a maximum of 24 days of blasting, we
have authorized up to 48 takes by Level B harassment and up to 5 takes
by Level A harassment of Steller sea lions.
Harbor seal--Previous monitoring efforts documented harbor seals
close to the shoreline Ulatka Head, on the northeastern side of
Iliuliuk Bay between 1 and 4 km from the project area, but they were
sighted throughout Iliuliuk Bay in all survey months (April-October)
(USACE 2022). They were most frequently sighted in the summer months,
with up to 43 sightings on a single day. Based on the high rate of
sightings within a few hundred
[[Page 82332]]
meters of the Level B harassment isopleth in the previous data, USACE
and NMFS conservatively assumed a maximum of 10 seals within the Level
B harassment threshold for each blast. While NMFS expects that the
monitoring and mitigation described later in this document will be
effective at preventing injurious take of marine mammals, we recognize
that harbor seals are common in the area, that animals may enter the
blasting area after charges have been set, and that there is a limit on
the amount of time detonation may be safely delayed. Harbor seals were
frequently sighted close to the Level B threshold distance and may be
difficult for observers to detect before charges are laid on a blasting
day. We therefore conservatively estimated up to two harbor seals may
be within the Level A harassment isopleth for up to 20 percent of the
blasting events. With a maximum take of 10 animals per day, multiplied
by a maximum of 24 days of blasting, we have authorized up to 240 takes
by Level B harassment and up to 5 takes by Level A harassment of harbor
seals.
Mitigation
In order to issue an IHA under section 101(a)(5)(D) of the MMPA,
NMFS must set forth the permissible methods of taking pursuant to the
activity, and other means of effecting the least practicable impact on
the species or stock and its habitat, paying particular attention to
rookeries, mating grounds, and areas of similar significance, and on
the availability of the species or stock for taking for certain
subsistence uses. NMFS regulations require applicants for incidental
take authorizations to include information about the availability and
feasibility (economic and technological) of equipment, methods, and
manner of conducting the activity or other means of effecting the least
practicable adverse impact upon the affected species or stocks, and
their habitat (50 CFR 216.104(a)(11)).
In evaluating how mitigation may or may not be appropriate to
ensure the least practicable adverse impact on species or stocks and
their habitat, as well as subsistence uses where applicable, NMFS
considers two primary factors:
(1) The manner in which, and the degree to which, the successful
implementation of the measure(s) is expected to reduce impacts to
marine mammals, marine mammal species or stocks, and their habitat, as
well as subsistence uses. This considers the nature of the potential
adverse impact being mitigated (likelihood, scope, range). It further
considers the likelihood that the measure will be effective if
implemented (probability of accomplishing the mitigating result if
implemented as planned), the likelihood of effective implementation
(probability implemented as planned), and;
(2) The practicability of the measures for applicant
implementation, which may consider such things as cost and impact on
operations.
In addition to the measures described later in this section, the
USACE will employ the following standard mitigation measures:
<bullet> Conduct a briefing between construction supervisors and
crews and the marine mammal monitoring team prior to the start of
construction, and when new personnel join the work, to explain
responsibilities, communication procedures, marine mammal monitoring
protocol, and operational procedures;
<bullet> For in-water and over-water heavy machinery work, if a
marine mammal comes within 10 m, operations must cease and vessels must
reduce speed to the minimum level required to maintain steerage and
safe working conditions;
<bullet> Work may only occur during daylight hours, when visual
monitoring of marine mammals can be conducted; and
<bullet> If take reaches the authorized limit for an authorized
species, the blasting activity will be stopped as these species
approach the Monitoring zones (table 6) to avoid additional take of
them.
Table 6--Monitoring and Pre-Clearance Zones for Blasting Activities for Species With Authorized Take
----------------------------------------------------------------------------------------------------------------
Pre-clearance zones (m)
--------------------------
Level A Level B Monitoring zones
harassment harassment (m)
thresholds thresholds
(PTS) (TTS)
----------------------------------------------------------------------------------------------------------------
Humpback whale.................................................... 345 1,918 2,500
Harbor Porpoise................................................... 1,214 4,500 5,000
Steller sea lion.................................................. 92 250 2,500
Harbor seal....................................................... 231 910 2,500
----------------------------------------------------------------------------------------------------------------
The USACE will implement the following mitigation requirements:
Establishment of Pre-clearance and Monitoring Zones--The USACE and
NMFS have identified pre-clearance zones associated with the distances
within which Level A harassment and Level B harassment are expected to
occur. Additionally, monitoring zones that extend beyond the pre-
clearance zones have been established. Monitoring zones provide utility
for observing by establishing monitoring protocols for areas adjacent
to the pre-clearance zones. Monitoring zones enable observers to be
aware of and communicate the presence of marine mammals in the project
area outside the Level B harassment pre-clearance zone and thus prepare
for a potential cessation of activity should the animal enter the Level
A harassment zone (table 6).
Pre-monitoring and Delay of Activities--Prior to the start of daily
in-water activity, or whenever a break in activity of 30 minutes or
longer occurs, the observers will observe the pre-clearance and
monitoring zones for a period of 30 minutes. Pre-clearance zones will
be considered cleared when a marine mammal has not been observed within
the zone for that 30-minute period. If any marine mammal is observed
within the Level A pre-clearance zone, activity cannot proceed until
the animal has left the zone or has not been observed for 15 minutes.
If marine mammals are observed within the Level B pre-clearance or
monitoring zones but outside of the Level A pre-clearance zones, work
may proceed in good visibility conditions. If work ceases for more than
30 minutes, the pre-activity monitoring of both the monitoring zones
and pre-clearance zones will commence.
In the event that a large whale for which take is not authorized is
sighted within either the monitoring or the Level A or Level B pre-
clearance zones during monitoring prior to placement of charges on a
planned blast day, USACE will evaluate whether environmental
[[Page 82333]]
conditions allow for blasting to be delayed to the following day. If
charges have already been laid before the whale is sighted, blasting
will not commence until the whale has been positively observed outside
of the monitoring zone, subject to the safety restrictions discussed
below.
Charges for blasting will not be laid if marine mammals are within
the Level A pre-clearance zone or appear likely to enter the Level A
pre-clearance zone. However, once charges are placed, they cannot be
safely left undetonated for more than 24 hours. For blasting, the
monitoring and pre-clearance zones will be monitored for a minimum of
30 minutes prior to detonating the blasts. If a marine mammal is
sighted within the Level A or Level B pre-clearance zones following the
emplacement of charges, detonation will be delayed until the zones are
clear of marine mammals for 30 minutes. This will continue as long as
practicable within the constraints of the blasting design but not
beyond sunset on the same day as the charges cannot lay dormant for
more than 24 hours, which may force the detonation of the blast in the
presence of marine mammals. All other legal measures to avoid injury
will be utilized; however, the charges will be detonated when delay is
no longer feasible.
Charges will be laid as early as possible in the morning and
stemming procedures will be used to fill the blasting holes to
potentially reduce the noise from the blasts. Blasting will only be
planned to occur in good visibility conditions, and at least 30 minutes
after sunrise and at least one hour prior to sunset. The zones will
also be monitored for 1 hour post-blasting.
If a detonation occurs when a marine mammal is known to be within
the Level A or Level B pre-clearance zones, USACE will observe the
blast area for two hours after the blasting event, or until visibility
or safety conditions decline to the point that monitoring is no longer
feasible, to determine as much as possible about the behavior and
physical status of the marine mammal affected by the blasting event.
Based on our evaluation of the applicant's planned measures, as
well as other measures considered by NMFS, NMFS has determined that the
listed 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 uses.
Monitoring and Reporting
In order to issue an IHA for an activity, section 101(a)(5)(D) of
the MMPA states that NMFS must set forth requirements pertaining to the
monitoring and reporting of such taking. The MMPA implementing
regulations at 50 CFR 216.104(a)(13) indicate that requests for
authorizations must include the suggested means of accomplishing the
necessary monitoring and reporting that will result in increased
knowledge of the species and of the level of taking or impacts on
populations of marine mammals that are expected to be present while
conducting the activities. Effective reporting is critical both to
compliance as well as ensuring that the most value is obtained from the
required monitoring.
Monitoring and reporting requirements prescribed by NMFS should
contribute to improved understanding of one or more of the following:
<bullet> Occurrence of marine mammal species or stocks in the area
in which take is anticipated (e.g., presence, abundance, distribution,
density);
<bullet> Nature, scope, or context of likely marine mammal exposure
to potential stressors/impacts (individual or cumulative, acute or
chronic), through better understanding of: (1) action or environment
(e.g., source characterization, propagation, ambient noise); (2)
affected species (e.g., life history, dive patterns); (3) co-occurrence
of marine mammal species with the activity; or (4) biological or
behavioral context of exposure (e.g., age, calving or feeding areas);
<bullet> Individual marine mammal responses (behavioral or
physiological) to acoustic stressors (acute, chronic, or cumulative),
other stressors, or cumulative impacts from multiple stressors;
<bullet> How anticipated responses to stressors impact either: (1)
long-term fitness and survival of individual marine mammals; or (2)
populations, species, or stocks;
<bullet> Effects on marine mammal habitat (e.g., marine mammal prey
species, acoustic habitat, or other important physical components of
marine mammal habitat); and,
<bullet> Mitigation and monitoring effectiveness.
Visual Monitoring
Monitoring will be conducted 30 minutes before, during, and 30
minutes after construction activities. In addition, observers must
record all incidents of marine mammal occurrence, regardless of
distance from activity, and must document any behavioral reactions in
concert with distance from construction activities.
Protected Species Observers (PSOs) will be land- and boat-based.
For blasting, three PSOs will be required (two land-based and one boat-
based). Observers will be stationed at locations that provide adequate
visual coverage for shutdown and monitoring zones. Potential
observation locations are depicted in Figure 3-1 of the applicant's
Marine Mammal Monitoring and Mitigation Plan. During blasting, pre-
blast monitoring, and post-blast monitoring, three observers will be on
duty. Optimal observation locations will be selected based on
visibility and the type of work occurring. All PSOs will be trained in
marine mammal identification and behaviors and are required to have no
other project-related tasks while conducting monitoring. In addition,
monitoring will be conducted by qualified observers, who will be placed
at the best vantage point(s) practicable to monitor for marine mammals
and implement shutdown/delay procedures when applicable. Monitoring of
construction activities must be conducted by qualified PSOs (see
below), who must have no other assigned tasks during monitoring
periods. The applicant must adhere to the following conditions when
selecting observers:
<bullet> Independent PSOs must be used (i.e., not construction
personnel);
<bullet> At least one PSO must have prior experience working as a
marine mammal observer during construction activities;
<bullet> Other PSOs may substitute education (degree in biological
science or related field) or training for experience;
<bullet> Where a team of three or more PSOs are required, a lead
observer or monitoring coordinator must be designated. The lead
observer must have prior experience working as a marine mammal observer
during construction; and
<bullet> The applicant must submit PSO curriculum vitaes for
approval by NMFS.
The applicant must ensure that observers have the following
additional qualifications:
<bullet> Ability to conduct field observations and collect data
according to assigned protocols;
<bullet> Experience or training in the field identification of
marine mammals, including the identification of behaviors;
<bullet> Sufficient training, orientation, or experience with the
construction
[[Page 82334]]
operation to provide for personal safety during observations;
<bullet> Writing skills sufficient to prepare a report of
observations including, but not limited to, the number and species of
marine mammals observed; dates and times when in-water construction
activities were conducted; dates, times, and reason for implementation
of mitigation (or why mitigation was not implemented when required);
and marine mammal behavior; and
<bullet> Ability to communicate orally, by radio or in person, with
project personnel to provide real-time information on marine mammals
observed in the area as necessary.
At least 24 hours prior to blasting, the USACE will notify the
Office of Protected Resources, NMFS Alaska Regional Office, and the
Alaska Regional Stranding Coordinator that blasting is planned to
occur, as well as notify these parties within 24 hours after blasting
that blasting actually occurred. If a marine mammals is known to be
within the Level A or Level B pre-clearance zones during a detonation,
USACE will report the following information within 24 hours of the
blasting event:
<bullet> Description of the blasting event;
<bullet> PSO positions and monitoring effort for the 24 hours
preceding the blast;
<bullet> Environmental conditions (e.g., Beaufort sea state,
visibility);
<bullet> Description of all marine mammal observations in the 24
hours preceding the incident;
<bullet> Species identification or description of the animal(s)
involved;
<bullet> Fate of the animal(s); and
<bullet> Photographs or video footage of the animal(s) (if
equipment is available).
A draft marine mammal monitoring report will be submitted to NMFS
within 90 days after the completion of construction activities. It will
include an overall description of work completed, a narrative regarding
marine mammal sightings, and associated PSO data sheets. Specifically,
the report must include:
<bullet> Date and time that monitored activity begins or ends;
<bullet> Construction activities occurring during each observation
period;
<bullet> Weather parameters (e.g., percent cover, visibility);
<bullet> Water conditions (e.g., sea state, tide state);
<bullet> Species, numbers, and, if possible, sex and age class of
marine mammals;
<bullet> Description of any observable marine mammal behavior
patterns, including bearing and direction of travel and distance from
construction activity;
<bullet> Distance from construction activities to marine mammals
and distance from the marine mammals to the observation point;
<bullet> Locations of all marine mammal observations; and
<bullet> Other human activity in the area.
If no comments are received from NMFS within 30 days, the draft
final report will constitute the final report. If comments are
received, a final report addressing NMFS comments must be submitted
within 30 days after receipt of comments.
In the unanticipated event that the specified activity likely
causes the take of a marine mammal in a manner prohibited by the IHA
(if issued), such as a serious injury or mortality, the USACE will
immediately cease the specified activities and report the incident to
the Office of Protected Resources, NMFS Alaska Regional Office, and the
Alaska Regional Stranding Coordinator. The report will include the
following information:
<bullet> Description of the incident;
<bullet> Environmental conditions (e.g., Beaufort sea state,
visibility);
<bullet> Description of all marine mammal observations in the 24
hours preceding the incident;
<bullet> Species identification or description of the animal(s)
involved;
<bullet> Fate of the animal(s); and
<bullet> Photographs or video footage of the animal(s) (if
equipment is available).
Activities will not resume until NMFS is able to review the
circumstances of the prohibited take. NMFS will work with the USACE to
determine what is necessary to minimize the likelihood of further
prohibited take and ensure MMPA compliance. The USACE will not be able
to resume their activities until notified by NMFS via letter, email, or
telephone.
In the event that the USACE discovers an injured or dead marine
mammal, and the lead PSO determines that the cause of the injury or
death is unknown and the death is relatively recent (e.g., in less than
a moderate state of decomposition as described in the next paragraph),
the USACE will immediately report the incident to the Office of
Protected Resources, NMFS Alaska Regional Office, and the Alaska
Regional Stranding Coordinator. The report will include the same
information identified in the paragraph above. Activities will be able
to continue while NMFS reviews the circumstances of the incident. NMFS
will work with the USACE to determine whether modifications in the
activities are appropriate.
In the event that the USACE discovers an injured or dead marine
mammal and the lead PSO determines that the injury or death is not
associated with or related to the activities authorized in the IHA
(e.g., previously wounded animal, carcass with moderate to advanced
decomposition, or scavenger damage), the USACE will report the incident
to the Office of Protected Resources, NMFS Alaska Regional Office, and
the NMFS Alaska Stranding Hotline and/or by email to the Alaska
Regional Stranding Coordinator, within 24 hours of the discovery. The
USACE will provide photographs, video footage (if available), or other
documentation of the stranded animal sighting to NMFS and the Marine
Mammal Stranding Coordinator.
Negligible Impact Analysis and Determination
NMFS has defined negligible impact as an impact resulting from the
specified activity that cannot be reasonably expected to, and is not
reasonably likely to, adversely affect the species or stock through
effects on annual rates of recruitment or survival (50 CFR 216.103). A
negligible impact finding is based on the lack of likely adverse
effects on annual rates of recruitment or survival (i.e., population-
level effects). An estimate of the number of takes alone is not enough
information on which to base an impact determination. In addition to
considering estimates of the number of marine mammals that might be
``taken'' through harassment, NMFS considers other factors, such as the
likely nature of any impacts or responses (e.g., intensity, duration),
the context of any impacts or responses (e.g., critical reproductive
time or location, foraging impacts affecting energetics), as well as
effects on habitat, and the likely effectiveness of the mitigation. We
also assess the number, intensity, and context of estimated takes by
evaluating this information relative to population status. Consistent
with the 1989 preamble for NMFS' implementing regulations (54 FR 40338,
September 29, 1989), the impacts from other past and ongoing
anthropogenic activities are incorporated into this analysis via their
impacts on the baseline (e.g., as reflected in the regulatory status of
the species, population size and growth rate where known, ongoing
sources of human-caused mortality, or ambient noise levels).
To avoid repetition, the discussion of our analysis applies to all
the species listed in table 1, given that the anticipated effects of
this activity on these different marine mammal stocks are expected to
be similar. There is little information about the nature or severity of
the impacts, or the size, status, or structure of any of these species
or
[[Page 82335]]
stocks that would lead to a different analysis for this activity.
As stated in the mitigation section, pre-clearance zones equal to
or exceeding Level A isopleths shown in table 6 for blasting will be
implemented for all species. Serious injury or mortality is not
anticipated nor authorized.
Behavioral disturbances of marine mammals to blasting, if any, are
expected to be mild and temporary due to the short-term duration of the
noise produced by the source and the fact that only a single blasting
event will occur on a given day. Additionally, blasting events will not
occur on consecutive days. Given the short duration of noise-generating
activities per day and that blasting events would occur on a maximum of
24 days, any harassment would be temporary. For all species except
humpbacks, there are no known biologically important areas near the
project zone that will be impacted by the construction activities. The
project area occupies a small percentage of the humpback whale feeding
BIA and Critical Habitat areas, and there is sufficient similar habitat
nearby. Acoustic impacts will be short-term and temporary in duration.
The region of Iliuliuk Bay where the project will take place is located
in a highly trafficked commercial port area with regular marine vessel
traffic.
In summary and as described above, the following factors primarily
support our determination that the impacts resulting from this activity
are not expected to adversely affect any of the species or stocks
through effects on annual rates of recruitment or survival:
<bullet> No serious injury or mortality is anticipated or
authorized;
<bullet> Authorized Level A harassment will be very small amounts
and of low degree;
<bullet> The intensity of anticipated takes by Level B harassment
is relatively low for all stocks. Level B harassment will be primarily
in the form of behavioral disturbance, resulting in avoidance of the
project areas around where blasting is occurring, with some TTS that
may limit the detection of acoustic cues for relatively brief amounts
of time;
<bullet> While a feeding BIA and Critical Habitat for humpback
whales exist in the action area, the planned activity occupies a small
percentage of the total BIA and of the Critical Habitat, and would
occur on a short term, temporary basis.
<bullet> The USACE will implement mitigation measures, such as pre-
clearance zones, for all in-water and over-water activities; and
<bullet> Monitoring reports from similar work in Alaska have
documented little to no effect on individuals of the same species
impacted by the specified activities (USACE, 2020).
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 monitoring and mitigation
measures, NMFS finds that the total marine mammal take from the planned
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.
Table 7 presents the number of animals that could be exposed to
received noise levels that may result in take by Level A or Level B
harassment for the construction at Iliuliuk Bay, Unalaska. Our analysis
shows that less than one-third of the best available population
estimate of each affected stock could be taken. Therefore, the numbers
of animals authorized to be taken for all species would be considered
small relative to the relevant stocks or populations even if each
estimated taking occurred to a new individual--an extremely unlikely
scenario. For harbor seals and Steller sea lions occurring in the
vicinity of the project site, there will almost certainly be some
overlap in individuals present day-to-day, and these takes are likely
to occur only within some small portion of the overall regional stock.
Table 7--Summary of Authorized Instances of Level A and Level B Harassment
----------------------------------------------------------------------------------------------------------------
Number of Number of
takes by takes by
Species DPS/stock Level B Level A Stock Percent of
harassment harassment abundance population
by stock by stock
----------------------------------------------------------------------------------------------------------------
Humpback whale...................... Western North Pacific. 0.96 0 1,107 0.1
Mexico--North Pacific. 3.36 0 4,973 0.1
Hawaii................ 43.68 3 10,103 0.5
Harbor seal......................... Aleutian Island Stock. 240 5 5,588 4.4
Harbor porpoise \1\................. Bering Sea............ 12 5 31,046 0.05
Gulf of Alaska........ ........... ........... ........... ...........
Steller sea lion.................... Western DPS........... 48 5 52,932 0.1
----------------------------------------------------------------------------------------------------------------
\1\ There is not enough information available to determine takes for separate stocks for harbor porpoise.
Calculations have been based on the best available stock abundance for the Gulf of Alaska stock, as there are
no available data for the Bering Sea stock. This number is conservative, because it represents a minimum value
of both stocks.
Based on the analysis contained herein of the planned activity
(including the mitigation and monitoring measures) and the anticipated
take of marine mammals, NMFS 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''
[[Page 82336]]
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.
Subsistence activities in Unalaska have historically included the
harvest of pinnipeds and sea otters. However, subsistence harvests of
marine mammals declined between 1994 and 2008 (the last year for which
data are available) (ADF&G 2022). Additionally, a ban on firearm
discharge within the city limits of the City of Unalaska means that
current subsistence harvesting typically occurs from skiffs in areas
outside of Dutch Harbor and Iliuliuk Bay, including Wide Bay, Kalekta
Bay, Bishop Point, Wislow Island, and Beaver Inlet. The planned
activity would not impact these areas.
Any impacts to marine mammals from the planned activity are likely
to be short-term and temporary, and limited to the area around the
blasting site. While a limited number of individuals may experience
PTS, there are no expected impacts to the availability of marine
mammals for subsistence uses due to the blasting activity.
Based on the description of the specified activity, and the
mitigation and monitoring measures, NMFS has determined that there will
not be an unmitigable adverse impact on subsistence uses from USACE's
construction activities.
Endangered Species Act
Section 7(a)(2) of the Endangered Species Act of 1973 (ESA; 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, in this case with NMFS Alaska
Regional Office.
There are two marine mammal species (western DPS Steller sea lion
and humpback whale (Mexico and Western North Pacific DPSs)) with
confirmed occurrence in the project area that are listed as endangered
under the ESA. The NMFS Alaska Regional Office Protected Resources
Division issued a Biological Opinion on November 16, 2023 under section
7 of the ESA, on the issuance of an IHA to USACE under section
101(a)(5)(D) of the MMPA by the NMFS Permits and Conservation Division.
The Biological Opinion concluded that the action is not likely to
jeopardize the continued existence of Western DPS Steller sea lions or
humpback whales from either the Mexico or Western North Pacific DPSs,
and is not likely to destroy or adversely modify humpback whale
critical habitat.
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 NOAA Administrative Order 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 determined
that the issuance of the IHA qualifies to be categorically excluded
from further NEPA review.
Authorization
As a result of these determinations, NMFS has issued an IHA to the
USACE for conducting confined blasting in Iliuliuk Bay, Unalaska
between January 1, 2024 and December 31, 2024, incorporating the
previously mentioned mitigation, monitoring, and reporting
requirements. The IHA can be found at: <a href="https://www.fisheries.noaa.gov/action/incidental-take-authorization-us-army-corps-engineers-unalaska-dutch-harbor-channel">https://www.fisheries.noaa.gov/action/incidental-take-authorization-us-army-corps-engineers-unalaska-dutch-harbor-channel</a>.
Dated: November 20, 2023.
Kimberly Damon-Randall,
Director, Office of Protected Resources, National Marine Fisheries
Service.
[FR Doc. 2023-25934 Filed 11-22-23; 8:45 am]
BILLING CODE 3510-22-P
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</html>Indexed from Federal Register on November 24, 2023.
This is legal information, not legal advice. Laws vary by jurisdiction and change frequently. Always verify current law with official sources and consult a licensed attorney in your jurisdiction for advice on your specific situation.