Notice2021-11718
Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to a Geophysical Survey of the Queen Charlotte Fault
Primary source
Metadata and text below are from the Federal Register, a public-domain U.S. government work. Always verify the official published version before relying on it for any legal matter.
Published
June 4, 2021
Issuing agencies
Commerce DepartmentNational Oceanic and Atmospheric Administration
Abstract
NMFS has received a request from the Lamont-Doherty Earth Observatory of Columbia University (L-DEO) for authorization to take marine mammals incidental to a marine geophysical survey of the Queen Charlotte Fault in the Northeast Pacific Ocean. The proposed survey would be funded by the National Science Foundation (NSF). 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, one-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 authorizations and agency responses will be summarized in the final notice of our decision.
Full Text
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[Federal Register Volume 86, Number 106 (Friday, June 4, 2021)]
[Notices]
[Pages 30006-30034]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2021-11718]
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DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
[RTID 0648-XB083]
Takes of Marine Mammals Incidental to Specified Activities;
Taking Marine Mammals Incidental to a Geophysical Survey of the Queen
Charlotte Fault
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 Lamont-Doherty Earth
Observatory of Columbia University (L-DEO) for authorization to take
marine mammals incidental to a marine geophysical survey of the Queen
Charlotte Fault in the Northeast Pacific Ocean. The proposed survey
would be funded by the National Science Foundation (NSF). 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, one-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
authorizations and agency responses will be summarized in the final
notice of our decision.
DATES: Comments and information must be received no later than July 6,
2021.
ADDRESSES: Comments should be addressed to Jolie Harrison, Chief,
Permits and Conservation Division, Office of Protected Resources,
National Marine Fisheries Service. Physical comments should be sent to
1315 East-West Highway, Silver Spring, MD 20910 and electronic comments
should be sent to <a href="/cdn-cgi/l/email-protection#703924205e3c110703301e1f11115e171f06"><span class="__cf_email__" data-cfemail="9bd2cfcbb5d7faece8dbf5f4fafab5fcf4ed">[email protected]</span></a>.
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 received electronically, including
all attachments, must not exceed a 25-megabyte file size. All comments
received are a part of the public record
[[Page 30007]]
and will generally be posted online at <a href="http://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act">www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act</a>
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: Ben Laws, Office of Protected
Resources, NMFS, (301) 427-8401. 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="http://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act">www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act</a>. In case of problems accessing these documents, please call the
contact listed above.
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 issued or, if the taking is limited to harassment, a notice of a
proposed incidental take authorization may be 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.
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.
Accordingly, NMFS plans to adopt NSF's Environmental Assessment
(EA), as we have preliminarily determined that it includes adequate
information analyzing the effects on the human environment of issuing
the IHA. NSF's EA is available at <a href="http://www.nsf.gov/geo/oce/envcomp/">www.nsf.gov/geo/oce/envcomp/</a>.
We will review all comments submitted in response to this notice
prior to concluding our NEPA process or making a final decision on the
IHA request.
Summary of Request
On December 3, 2019, NMFS received a request from L-DEO for an IHA
to take marine mammals incidental to a geophysical survey of the Queen
Charlotte Fault (QCF) off of Alaska and British Columbia, Canada. L-DEO
submitted a revised version of the application on April 2, 2020. On
April 10, 2020, L-DEO informed NMFS that the planned survey would be
deferred to 2021 as a result of issues related to the COVID-19
pandemic. L-DEO subsequently submitted revised versions of the
application on October 22 and December 16, 2020, the latter of which
was deemed adequate and complete. A final, revised version was
submitted on January 11, 2021. L-DEO's request is for take of 21
species of marine mammals by Level B harassment. In addition, NMFS
proposes to authorize take by Level A harassment for seven of these
species.
Description of Proposed Activity
Overview
Researchers from L-DEO, the University of New Mexico, and Western
Washington University, with funding from NSF, propose to conduct a
high-energy seismic survey from the Research Vessel (R/V) Marcus G.
Langseth (Langseth) at the QCF in the northeast Pacific Ocean during
late summer 2021. Other research collaborators include Dalhousie
University, the Geological Survey of Canada, and the U.S. Geological
Survey. The proposed two-dimensional (2-D) seismic survey would occur
within the Exclusive Economic Zones (EEZ) of the United States and
Canada, including in Canadian territorial waters. The survey would use
a 36-airgun towed array with a total discharge volume of ~6,600 cubic
inches (in\3\) as an acoustic source, acquiring return signals using
both a towed streamer as well as ocean bottom seismometers (OBSs).
The proposed study would use 2-D seismic surveying to characterize
crustal and uppermost mantle velocity structure, fault zone
architecture and rheology, and seismicity of the QCF. The QCF system is
an approximately 1,200 kilometer (km)-long onshore-offshore transform
system connecting the Cascadia and Alaska-Aleutian subduction zones;
the QCF is the approximately 900 km-long offshore component of the
transform system. The purpose of the proposed study is to characterize
an approximately 450-km segment of the fault that encompasses
systematic variations in key parameters in space and time: (1) Changes
in fault obliquity relative to Pacific-North American plate motion
leading to increased convergence from north to south; (2) Pacific plate
age and theoretical mechanical thickness decrease from north to south;
and (3) a shift in Pacific plate motion at approximately 12-6 million
years ago that may have increased convergence along the entire length
of the fault, possibly initiating underthrusting in the southern
portion of the study area. Current understanding of how these
variations are expressed through seismicity, crustal-scale deformation,
and lithospheric structure and dynamics is limited due to lack of
instrumentation and modern seismic imaging.
Dates and Duration
The proposed survey is expected to last for approximately 36 days,
including approximately 27 days of seismic operations, 3 days of
equipment deployment/retrieval, 2 days of transits, and 4 contingency
days (accounting for potential delays due to, e.g., weather). R/V
Langseth would likely leave out of and return to port in Ketchikan,
Alaska, during July-August 2021.
Specific Geographic Region
The proposed survey would occur within the area of approximately
52-57[deg] N and approximately 131-137[deg] W. Representative survey
tracklines are shown in Figure 1. Some deviation in actual track lines,
including the order of survey operations, could be necessary for
reasons such as science drivers, poor data quality, inclement weather,
or mechanical issues with the research vessel and/or equipment. The
survey is proposed to occur within the EEZs of the United States and
Canada, including Alaskan state waters and Canadian territorial waters,
ranging in depth from
[[Page 30008]]
50-2,800 meters (m). Approximately 4,250 km of transect lines would be
surveyed, with 13 percent of the transect lines in Canadian territorial
waters. Most of the survey (69 percent) would occur in deep water
(>1,000 m), 30 percent would occur in intermediate water (100-1,000 m
deep), and approximately 1 percent would take place in shallow water
<100 m deep.
Note that the MMPA does not apply in Canadian territorial waters.
L-DEO is subject only to Canadian law in conducting that portion of the
survey. However, NMFS has calculated the expected level of incidental
take in the entire activity area (including Canadian territorial
waters) as part of the analysis supporting our determination under the
MMPA that the activity will have a negligible impact on the affected
species (see Estimated Take and Negligible Impact Analysis and
Determination).
BILLING CODE 3510-22-P
[[Page 30009]]
[GRAPHIC] [TIFF OMITTED] TN04JN21.003
BILLING CODE 3510-22-C
[[Page 30010]]
Detailed Description of Specific Activity
The procedures to be used for the proposed survey would be similar
to those used during previous seismic surveys by L-DEO and would use
conventional seismic methodology. The surveys would involve one source
vessel, the R/V Langseth. R/V Langseth would deploy an array of 36
airguns as an energy source with a total volume of 6,600 in\3\. The
array consists of 36 elements, including 20 Bolt 1500LL airguns with
volumes of 180 to 360 in\3\ and 16 Bolt 1900LLX airguns with volumes of
40 to 120 in\3\. The airgun array configuration is illustrated in
Figure 2-11 of NSF and USGS's Programmatic Environmental Impact
Statement (PEIS; NSF-USGS, 2011). (The PEIS is available online at:
<a href="http://www.nsf.gov/geo/oce/envcomp/usgs-nsf-marine-seismic-research/nsf-usgs-final-eis-oeis-with-appendices.pdf">www.nsf.gov/geo/oce/envcomp/usgs-nsf-marine-seismic-research/nsf-usgs-final-eis-oeis-with-appendices.pdf</a>). The vessel speed during seismic
operations would be approximately 4.2 knots (kn) (~7.8 km/hour) during
the survey and the airgun array would be towed at a depth of 12 m. The
receiving system would consist of OBSs and a towed hydrophone streamer
with a nominal length of 15 km (OBS and multi-channel seismic (MCS)
shooting). As the airguns are towed along the survey lines, the
hydrophone streamer would transfer the data to the on-board processing
system, and the OBSs would receive and store the returning acoustic
signals internally for later analysis.
Approximately 60 short-period OBSs would be deployed and
subsequently retrieved at a total of 123 sites in multiple phases from
a second vessel, the Canadian Coast Guard ship John P. Tully (CCGS
Tully). Along OBS refraction lines, OBSs would be deployed by CCGS
Tully at 10 km intervals, with a spacing of 5 km over the central 40 km
of the fault zone for fault-normal crossings. Twenty-eight broadband
OBS instruments would also collect data during the survey and would be
deployed prior to the active-source seismic survey, depending on
logistical constraints. When an OBS is ready to be retrieved, an
acoustic release transponder (pinger) interrogates the instrument at a
frequency of 8-11 kHz; a response is received at 11.5-13 kHz. The burn-
wire release assembly is then activated, and the instrument is released
from its 80-kg anchor to float to the surface. Take of marine mammals
is not expected to occur incidental to L-DEO's use of OBSs.
The airguns would fire at a shot interval of 50 m (approximately 23
s) during MCS shooting with the hydrophone streamer (approximately 42
percent of survey effort), at a 150-m interval (approximately 69 s)
during refraction surveying to OBSs (approximately 29 percent of survey
effort), and at a shot interval of every minute (approximately 130 m)
during turns (approximately 29 percent of survey effort).
Short-period OBSs would be deployed first along five OBS refraction
lines by CCGS Tully. Two OBS lines run parallel to the coast, and three
are perpendicular to the coast; one perpendicular line is located off
Southeast Alaska, one is off Haida Gwaii, British Columbia, and another
is located in Dixon Entrance. Please see Figure 1 for all location
references. Following refraction shooting of a single line, short-
period instruments on that line would be recovered, serviced, and
redeployed on a subsequent refraction line while MCS data would be
acquired by the Langseth. MCS lines would be acquired off Southeast
Alaska, Haida Gwaii, and Dixon Entrance. The coast-parallel OBS
refraction transect nearest to shore would only be surveyed once at OBS
shot spacing. The other coast-parallel OBS refraction transect (on the
ocean side) would be acquired twice, once during refraction and once
during reflection surveys. In addition, portions of the three coast-
perpendicular OBS refraction lines would also be surveyed twice, once
for OBS shot spacing and once for MCS shot spacing. The coincident
reflection/refraction profiles that run parallel to the coast would be
acquired in multiple segments to ensure straight-line geometry.
Sawtooth transits during which seismic data would be acquired would
take place between transect lines when possible; otherwise, boxcar
turns would be performed to save time. Both reflection and refraction
surveys would use the same airgun array with the same discharge volume.
There could be additional seismic operations associated with turns,
airgun testing, and repeat coverage of any areas where initial data
quality is sub-standard, and 25 percent has been added to the assumed
survey line-kms to account for this potential.
Note that the location of some tracklines has been modified from
the original proposal as represented in Figure 1 and reflected in the
take estimation analysis (see Estimated Take). However, these minor
modifications do not substantively impact the location of survey effort
or the proportion of survey effort in different depth bins and,
therefore, the original take estimates remain accurate.
In addition to the operations of the airgun array, a multibeam
echosounder (MBES), a sub-bottom profiler (SBP), and an Acoustic
Doppler Current Profiler (ADCP) would be operated from R/V Langseth
continuously during the seismic surveys, but not during transit to and
from the survey area. Take of marine mammals is not expected to occur
incidental to use of the MBES, SBP, or ADCP because they will be
operated only during seismic acquisition, and it is assumed that,
during simultaneous operations of the airgun array and the other
sources, any marine mammals close enough to be affected by the MBES,
SBP, and ADCP would already be affected by the airguns. However,
whether or not the airguns are operating simultaneously with the other
sources, given the other sources' characteristics (e.g., narrow
downward-directed beam), marine mammals would experience no more than
one or two brief ping exposures from them, if any exposure were to
occur. 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.
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="http://www.fisheries.noaa.gov/find-species">www.fisheries.noaa.gov/find-species</a>).
Table 1 lists all species with expected potential for occurrence in
the survey area 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.
For taxonomy, we follow Committee on Taxonomy (2020). 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's SARs). While no mortality is
anticipated or authorized here, PBR and annual serious injury and
mortality from anthropogenic sources are included here
[[Page 30011]]
as gross indicators of the status of the species 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. Pacific and Alaska SARs. All MMPA stock information
presented in Table 1 is the most recent available at the time of
publication and is available in the 2019 SARs (Caretta et al., 2020;
Muto et al., 2020) and draft 2020 SARs (available online at:
<a href="http://www.fisheries.noaa.gov/national/marine-mammal-protection/draft-marine-mammal-stock-assessment-reports">www.fisheries.noaa.gov/national/marine-mammal-protection/draft-marine-mammal-stock-assessment-reports</a>). Where available, abundance and status
information is also presented for marine mammals in British Columbia
waters.
Twenty-one species (with 28 managed stocks) are considered to have
the potential to occur in the proposed survey area. Species that could
potentially occur in the proposed research area but are not likely to
be harassed due to the rarity of their occurrence (i.e., are considered
extralimital or rare visitors to southeast Alaska/northern British
Columbia) are described briefly but omitted from further analysis.
These generally include species that do not normally occur in the area
but for which there are one or more occurrence records that are
considered beyond the normal range of the species. These species
include pygmy sperm whale (Kogia breviceps), dwarf sperm whale (K.
sima), Blainville's beaked whale (Mesoplodon densirostris), Hubbs'
beaked whale (Mesoplodon carlhubbsi), false killer whale (Pseudorca
crassidens), short-finned pilot whale (Globicephala macrorhynchus),
common bottlenose dolphin (Tursiops truncatus), common dolphin
(Delphius delphis), striped dolphin (Stenella coeruleoalba), and rough-
toothed dolphin (Steno bredanensis), which are all typically
distributed further south in the California Current ecosystem, and
beluga whales (Delphinapterus leucas), which are found further north,
with a population in Yakutat Bay.
The North Pacific right whale (Eubalaena japonica) historically
occurred across the North Pacific Ocean in subpolar to temperate
waters, including waters off the coast of British Columbia (Scarff,
1986; Clapham et al., 2004). Sightings of this endangered species are
now extremely rare, occurring primarily in the Okhotsk Sea and the
eastern Bering Sea (Brownell et al., 2001; Shelden et al., 2005; Wade
et al., 2006; Zerbini et al., 2010). In 2013, two North Pacific right
whale sightings were made off the coast of British Columbia (U.S.
Department of the Navy, 2015). There have also been four sightings,
each of a single North Pacific right whale, in California waters within
approximately the last 30 years (most recently in 2017) (Carretta et
al., 1994; Brownell et al., 2001; Price, 2017). There is a very low
probability of encountering this species in the action area, and it is
not discussed further.
There are eight killer whale stocks recognized in the U.S. Pacific,
with Southern Resident killer whales being the only ESA-listed
population. Southern Resident killer whales primarily occur in the
southern Strait of Georgia, Strait of Juan de Fuca, Puget Sound, and
the southern half of the west coast of Vancouver Island (Carretta et
al., 2020). However, they have been observed in southeast Alaska. In
2007, whales from L-pod were sighted off Chatham Strait, Alaska, the
farthest north they have ever been documented (Carretta et al., 2020).
During the summer, Southern Resident killer whales typically spend
their time within the inland waters of Washington and southern British
Columbia, south of the proposed survey area. There is a very low
probability of encountering this stock in the action area, and it is
not discussed further.
In addition, the northern sea otter (Enhydra lutris kenyoni) is
found in coastal waters of Alaska. However, this species is managed by
the U.S. Fish and Wildlife Service and is not considered further in
this document.
Table 1--Marine Mammals That Could Occur in the Survey Area
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ESA/ MMPA Stock abundance
status; (CV, Nmin, most British Annual M/
Common name Scientific name Stock strategic (Y/ recent abundance Columbia PBR SI \4\
N) \1\ survey) \2\ abundance \3\
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Order Cetartiodactyla--Cetacea--Superfamily Mysticeti (baleen whales)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Eschrichtiidae: Gray whale Eschrichtius Eastern North -; N 26,960 (0.05; .............. 801 131
robustus. Pacific (ENP) *. 25,849; 2016).
Western North E/D; Y 290 (n/a; 271; .............. 0.12 Unk
Pacific (WNP) *. 2016).
Family Balaenopteridae
(rorquals):
Humpback whale............... Megaptera Central North E/D; Y 10,103 (0.3; 7,891; 1,029 83 26
novaeangliae kuzira. Pacific (CNP) *. 2006).
Minke whale.................. Balaenoptera Alaska *............ -; N Unknown............ 522 Undet. 0
acutorostrata
scammoni.
Sei whale.................... B. borealis borealis ENP................. E/D; Y 519 (0.4; 374; .............. 0.75 >=0.2
2014).
Fin whale.................... B. physalus physalus Northeast Pacific *. E/D; Y Unknown............ 329 Undet. 0.6
Blue whale................... B. musculus musculus ENP................. E/D; Y 1,496 (0.44; 1,050; .............. \7\1.2 >=19.4
2014).
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Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
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Family Physeteridae: Sperm whale Physeter North Pacific *..... E/D; Y Unknown............ .............. Undet. 3.5
macrocephalus.
Family Ziphiidae (beaked whales):
Cuvier's beaked whale........ Ziphius cavirostris. Alaska *............ -; N Unknown............ .............. Undet. 0
Baird's beaked whale......... Berardius bairdii... Alaska *............ -; N Unknown............ .............. Undet. 0
Stejneger's beaked whale..... Mesoplodon Alaska *............ -; N Unknown............ .............. Undet. 0
stejnegeri.
Family Delphinidae:
[[Page 30012]]
Pacific white-sided dolphin.. Lagenorhynchus North Pacific \6\... -; N 26,880 (n/a; 22,160 Undet. 0
obliquidens. 26,880; 1990).
Northern right whale dolphin. Lissodelphis CA/OR/WA............ -; N 26,556 (0.44; .............. 179 3.8
borealis. 18,608; 2014).
Risso's dolphin.............. Grampus griseus..... CA/OR/WA............ -; N 6,336 (0.32; 4,817; .............. 46 >=3.7
2014).
Killer whale................. Orcinus orca \5\.... ENP Offshore........ -; N 300 (0.1; 276; 371 2.8 0
2012).
ENP Gulf of Alaska, -; N 587 (n/a; 2012).... 5.9 0.8
Aleutian Islands,
and Bering Sea
Transient.
ENP West Coast -; N 349 (n/a; 2018).... 3.5 0.4
Transient.
ENP Alaska Resident. -; N 2,347 (n/a; 2012).. 24 1
Northern Resident... -; N 302 (n/a; 2018).... 2.2 0.2
Family Phocoenidae (porpoises):
Harbor porpoise.............. Phocoena phocoena Southeast Alaska *.. -; Y Unknown............ 8,091 Undet. 34
vomerina.
Dall's porpoise.............. Phocoenoides dalli Alaska \6\.......... -; N 83,400 (0.097; n/a; 5,303 Undet. 38
dalli. 1991).
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Order Carnivora--Superfamily Pinnipedia
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Otariidae (eared seals and
sea lions):
Northern fur seal............ Callorhinus ursinus. Pribilof Islands/ D; Y 608,143 (0.2; .............. 11,067 387
Eastern Pacific. 514,738; 2018).
California sea lion.......... Zalophus United States....... -/-; N 257,606 (N/A, .............. 14,011 >=321
californianus. 233,515, 2014).
Steller sea lion............. Eumetopias jubatus Western U.S. *...... E/D; Y 52,932 (n/a; 2019). 15,348 318 255
jubatus.
E. j. monteriensis.. Eastern U.S. *...... -/-; N 43,201 (n/a; 2017). 2,592 112
Family Phocidae (earless seals):
Harbor seal.................. Phoca vitulina Sitka/Chatham Strait -; N 13,289 (n/a; 24,916 356 77
richardii. 11,883; 2015).
Dixon/Cape Decision. -; N 23,478 (n/a; 644 69
21,453; 2015).
Clarence Strait..... -; N 27,659 (n/a; 746 40
24,854; 2015).
Northern elephant seal....... Mirounga California Breeding. -; N 179,000 (n/a; .............. 4,882 8.8
angustirostris. 81,368; 2010).
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* Stocks marked with an asterisk are addressed in further detail in text below.
\1\ 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.
\2\ NMFS marine mammal stock assessment reports 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>. CV is
coefficient of variation; Nmin is the minimum estimate of stock abundance. In some cases, CV is not applicable. For most stocks of killer whales, the
abundance values represent direct counts of individually identifiable animals; therefore there is only a single abundance estimate with no associated
CV. For certain stocks of pinnipeds, abundance estimates are based upon observations of animals (often pups) ashore multiplied by some correction
factor derived from knowledge of the species' (or similar species') life history to arrive at a best abundance estimate; therefore, there is no
associated CV. In these cases, the minimum abundance may represent actual counts of all animals ashore.
\3\ Total abundance estimates for animals in British Columbia based on surveys of the Strait of Georgia, Johnstone Strait, Queen Charlotte Sound, Hecate
Strait, and Dixon Entrance. This column represents estimated abundance of animals in British Columbia, where available, but does not necessarily
represent additional stocks. Please see Best et al. (2015) and Pitcher et al. (2007) for additional information.
\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, subsistence hunting, ship strike). Annual M/SI often cannot be determined precisely and is in some cases presented as a minimum
value. All M/SI values are as presented in the draft 2020 SARs.
\5\ Transient and resident killer whales are considered unnamed subspecies (Committee on Taxonomy, 2020).
\6\ Abundance estimates for these stocks are not considered current. PBR is therefore considered undetermined for these stocks, as there is no current
minimum abundance estimate for use in calculation. We nevertheless present the most recent abundance estimates, as these represent the best available
information for use in this document.
\7\ This stock is known to spend a portion of time outside the U.S. EEZ. Therefore, the PBR presented here is the allocation for U.S. waters only and is
a portion of the total. The total PBR for blue whales is 2.1 (7/12 allocation for U.S. waters). Annual M/SI presented for these species is for U.S.
waters only.
Table 1 denotes the status of species and stocks under the U.S.
MMPA and ESA. We note also that under Canada's Species at Risk Act, the
sei whale and blue whale are listed as endangered; the fin whale and
northern resident, offshore, and transient populations of killer whales
are listed as threatened; and the humpback whale, harbor porpoise, and
Steller sea lion are considered species of special concern.
Two populations of gray whales are recognized, eastern and western
North Pacific (ENP and WNP). WNP whales are known to feed in the
Okhotsk Sea and off of Kamchatka before migrating south to poorly known
wintering grounds, possibly in the South China Sea. The two populations
have historically been considered geographically isolated from each
other; however, data from satellite-tracked whales indicate that there
is some overlap between the stocks. Two WNP whales were tracked from
Russian foraging areas along the Pacific rim to Baja California (Mate
et al., 2011), and, in one case where the satellite tag remained
attached to the whale for a
[[Page 30013]]
longer period, a WNP whale was tracked from Russia to Mexico and back
again (IWC, 2012). A number of whales are known to have occurred in the
eastern Pacific through comparisons of ENP and WNP photo-identification
catalogs (IWC, 2012; Weller et al., 2011; Burdin et al., 2011).
Therefore, a portion of the WNP population is assumed to migrate, at
least in some years, to the eastern Pacific during the winter breeding
season. Based on guidance provided through interagency consultation
under section 7 of the ESA, approximately 0.1 percent of gray whales
occurring in southeast Alaska and northern British Columbia are likely
to be from the Western North Pacific stock; the rest would be from the
Eastern North Pacific stock.
Prior to 2016, humpback whales were listed under the ESA as an
endangered species worldwide. Following a 2015 global status review
(Bettridge et al., 2015), NMFS delineated 14 distinct population
segments (DPS) with different listing statuses (81 FR 62259; September
8, 2016) pursuant to the ESA. The DPSs that occur in U.S. waters do not
necessarily equate to the existing stocks designated under the MMPA and
shown in Table 1.
In the eastern North Pacific, three humpback whale DPSs may occur:
The Hawaii DPS (not listed), Mexico DPS (threatened), and Central
America DPS (endangered). Individuals encountered in the proposed
survey area would likely be from the Hawaii DPS, followed by the Mexico
DPS; individuals from the Central America DPS are unlikely to feed in
northern British Columbia and Southeast Alaska (Ford et al., 2014).
According to Wade (2017), in southeast Alaska and northern British
Columbia, encountered whales are most likely to be from the Hawaii DPS
(96.1 percent), but could be from the Mexico DPS (3.8 percent).
Although no comprehensive abundance estimate is available for the
Alaska stock of minke whales, recent surveys provide estimates for
portions of the stock's range. A 2010 survey conducted on the eastern
Bering Sea shelf produced a provisional abundance estimate of 2,020 (CV
= 0.73) whales (Friday et al., 2013). This estimate is considered
provisional because it has not been corrected for animals missed on the
trackline, animals submerged when the ship passed, or responsive
movement. Additionally, line-transect surveys were conducted in shelf
and nearshore waters (within 30-45 nautical miles of land) in 2001-2003
between the Kenai Peninsula (150[deg] W) and Amchitka Pass (178[deg]
W). Minke whale abundance was estimated to be 1,233 (CV = 0.34) for
this area (also not been corrected for animals missed on the trackline)
(Zerbini et al., 2006). The majority of the sightings were in the
Aleutian Islands, rather than in the Gulf of Alaska, and in water
shallower than 200 m. These estimates cannot be used as an estimate of
the entire Alaska stock of minke whales because only a portion of the
stock's range was surveyed. Similarly, although a comprehensive
abundance estimate is not available for the northeast Pacific stock of
fin whales, provisional estimates representing portions of the range
are available. The same 2010 survey of the eastern Bering Sea shelf
provided an estimate of 1,061 (CV = 0.38) fin whales (Friday et al.,
2013). The estimate is not corrected for missed animals, but is
expected to be robust as previous studies have shown that only small
correction factors are needed for fin whales (Barlow, 1995). Zerbini et
al. (2006) produced an estimate of 1,652 (95 percent CI: 1,142-2,389)
fin whales for the area described above.
Current and historical estimates of the abundance of sperm whales
in the North Pacific are considered unreliable, and caution should be
exercised in interpreting published estimates (Muto et al., 2017).
However, Kato and Miyashita (1998) produced an abundance estimate of
102,112 (CV = 0.155) sperm whales in the western North Pacific
(believed to be positively biased). The number of sperm whales
occurring within Alaska waters is unknown.
Very little information is available regarding beaked whale stocks
in Alaska, with no reliable abundance estimates available for any
stock. Sightings of all beaked whale species are rare in Alaska, and
their presence and distribution have mostly been inferred from
stranding data. During long-term passive acoustic monitoring conducted
at five sites in the Gulf of Alaska from 2011-15, all three species
were detected at three sites located on the continental slope and
offshore seamounts (Rice et al., 2021). There was no clear diel or
interannual pattern for any species at any site. However, a different
species was predominant at each site and, when detected at the same
locations, detection peaks were all seasonally offset, demonstrating
some degree of habitat partitioning. The authors noted that detections
for all three beaked whale species were low throughout the summer.
Stranding records exist for all three species of beaked whale in the
survey area.
Using 2010-2012 survey data for the inland waters of southeast
Alaska, Dahlheim et al. (2015) calculated a combined abundance estimate
for harbor porpoise in the northern (including Cross Sound, Icy Strait,
Glacier Bay, Lynn Canal, Stephens Passage, and Chatham Strait) and
southern (including Frederick Sound, Sumner Strait, Wrangell and
Zarembo Islands, and Clarence Strait as far south as Ketchikan) regions
of the inland waters of 975 (95 percent CI = 857-1,109). This abundance
estimate was subsequently corrected for detection biases, which are
expected to be high for harbor porpoise (Muto et al., 2020). The
resulting abundance estimates are 553 harbor porpoise (CV = 0.13) in
the northern inland waters and 801 harbor porpoise (CV = 0.15) in the
southern inland waters (Muto et al., 2020).
The Steller sea lion ranges from Japan, through the Okhotsk and
Bering Seas, to central California. It consists of two morphologically,
ecologically, and behaviorally separate DPSs: The Eastern, which
includes sea lions in southeast Alaska, British Columbia, Washington,
Oregon, and California; and the Western, which includes sea lions in
all other regions of Alaska, as well as Russia and Japan. At the time
of their initial listing under the ESA, Steller sea lions were
considered a single population listed as threatened. In 1997, following
a status review, NMFS established two DPSs of Steller sea lions, and
issued a final determination to list the Western DPS as endangered
under the ESA. The Eastern DPS of Steller sea lion was delisted in
2013. According to Hastings et al. (2020), approximately 2.2 percent of
Steller sea lions occurring in the proposed action area are likely to
be from the Western DPS; the rest would be from the Eastern DPS.
Important Habitat
Several biologically important areas (BIA) for marine mammals are
recognized in southeast Alaska, and critical habitat is designated in
southeast Alaska for the Steller sea lion (58 FR 45269; August 27,
1993) and the Mexico DPS of humpback whale (86 FR 21082; April 21,
2021). Note that although the eastern DPS of Steller sea lion was
delisted in 2013, the change in listing status does not affect the
designated critical habitat. Critical habitat is defined by section 3
of the ESA as (1) the specific areas within the geographical area
occupied by the species, at the time it is listed, on which are found
those physical or biological features (a) essential to the conservation
of the species and (b) which may require special management
considerations or protection; and (2) specific areas outside the
geographical area occupied by the
[[Page 30014]]
species at the time it is listed, upon a determination by the Secretary
that such areas are essential for the conservation of the species.
Mexico DPS humpback whale critical habitat includes marine waters
in Washington, Oregon, California, and Alaska. Only the areas
designated in southeast Alaska fall within the survey area. The
relevant designated critical habitat (Unit 10) extends from 139[deg]24'
W, southeastward to the U.S. border with Canada. The area also extends
offshore to a boundary drawn along the 2,000-m isobath. The essential
feature for Mexico DPS humpback whale critical habitat is prey species,
primarily euphausiids and small pelagic schooling fishes of sufficient
quality, abundance, and accessibility within humpback whale feeding
areas to support feeding and population growth. This area was drawn to
encompass well-established feeding grounds in southeast Alaska and an
identified feeding BIA (86 FR 21082; April 21, 2021). Humpback whales
occur year-round in this unit, with highest densities occurring in
summer and fall (Baker et al., 1985, 1986).
Critical habitat for humpback whales has been designated under
Canadian law in four locations in British Columbia (DFO, 2013),
including in the waters of the survey area off Haida Gwaii (Langara
Island and Southeast Moresby Island). These areas show persistent
aggregations of humpback whales and have features such as prey
availability, suitable acoustic environment, water quality, and
physical space that allow for feeding, foraging, socializing, and
resting (DFO, 2013).
Designated Steller sea lion critical habitat includes terrestrial,
aquatic, and air zones that extend 3,000 ft (0.9 km) landward, seaward,
and above each major rookery and major haul-out in Alaska. Within the
survey area, critical habitat is located on islands off the coast of
southeast Alaska (e.g., Sitka, Coronation Island, Noyes Island, and
Forrester Island). The physical and biological features identified for
the aquatic areas of Steller sea lion designated critical habitat that
occur within the survey area are those that support foraging, such as
adequate prey resources and available foraging habitat. The proposed
survey tracklines do not directly overlap any areas of Steller sea lion
critical habitat, though the extent of the estimated ensonified area
associated with the survey would overlap with units of Steller sea lion
critical habitat. However, the brief duration of ensonification for any
critical habitat unit leads us to conclude that any impacts on Steller
sea lion habitat would be insignificant and would not affect the
conservation value of the critical habitat.
For humpback whales, seasonal feeding BIAs for spring (March-May),
summer (June-August), and fall (September-November) are recognized in
southeast Alaska (Ferguson et al., 2015). It should be noted that the
aforementioned designated critical habitat in the survey area was based
in large part on the same information that informed an understanding of
the BIAs. Though the BIAs are not synonymous with critical habitat
designated under the ESA, they were regarded by the humpback whale
critical habitat review team as an important source of information and
informative to their review of areas that meet the definition of
critical habitat for humpback whales (86 FR 21082; April 21, 2021). The
aforementioned southeast Alaska unit of designated critical habitat
encompasses the BIAs, with the offshore and nearshore boundaries
corresponding with the BIA boundary.
A separate feeding BIA is recognized in southeast Alaska for gray
whales. Once considered only a migratory pathway, the Gulf of Alaska is
now known to provide foraging and overwintering habitat for ENP gray
whales (Ferguson et al., 2015). Based on the regular occurrence of
feeding gray whales (including repeat sightings of individuals across
years) off southeast Alaska, an area off of Sitka is recognized. The
greatest densities of gray whales on the feeding area in southeast
Alaska occur from May to November. However, this area is located to the
north of the proposed survey area and would not be expected to be
meaningfully impacted by the survey activities. A separate migratory
BIA is recognized as extending along the continental shelf throughout
the Gulf of Alaska. During their annual migration, most gray whales
pass through the Gulf of Alaska in the fall (November through January;
southbound) and again in the spring (March through May; northbound)
(Ferguson et al., 2015). Therefore, the planned survey would not be
expected to impact gray whale migratory habitat due to the timing of
the survey in late summer. No important behaviors of gray whales in
either the feeding or migratory BIAs are expected to be affected. For
more information on BIAs, please see Ferguson et al. (2015) or visit
<a href="https://oceannoise.noaa.gov/biologically-important-areas">https://oceannoise.noaa.gov/biologically-important-areas</a>.
Unusual Mortality Events (UME)
A UME is defined under the MMPA as ``a stranding that is
unexpected; involves a significant die-off of any marine mammal
population; and demands immediate response.'' For more information on
UMEs, please visit: <a href="http://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-unusual-mortality-events">www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-unusual-mortality-events</a>. There is a currently
ongoing UME affecting gray whales throughout their migratory range.
Since January 1, 2019, elevated gray whale strandings have occurred
along the west coast of North America from Mexico through Alaska. As of
May 6, 2021, there have been a total of 454 whales reported in the
event, with approximately 218 dead whales in Mexico, 218 whales in the
United States (62 in California; 10 in Oregon; 53 in Washington, 93 in
Alaska), and 18 whales in British Columbia, Canada. For the United
States, the historical 18-year 5-month average (Jan-May) is 14.8 whales
for the four states for this same time-period. Several dead whales have
been emaciated with moderate to heavy whale lice (cyamid) loads.
Necropsies have been conducted on a subset of whales with additional
findings of vessel strike in three whales and entanglement in one
whale. In Mexico, 50-55 percent of the free-ranging whales observed in
the lagoons in winter have been reported as ``skinny'' compared to the
annual average of 10-12 percent ``skinny'' whales normally seen. The
cause of the UME is as yet undetermined. For more information, please
visit: <a href="http://www.fisheries.noaa.gov/national/marine-life-distress/2019-2020-gray-whale-unusual-mortality-event-along-west-coast-and">www.fisheries.noaa.gov/national/marine-life-distress/2019-2020-gray-whale-unusual-mortality-event-along-west-coast-and</a>.
Another recent, notable UME involved large whales and occurred in
the western Gulf of Alaska and off of British Columbia, Canada.
Beginning in May 2015, elevated large whale mortalities (primarily fin
and humpback whales) occurred in the areas around Kodiak Island,
Afognak Island, Chirikof Island, the Semidi Islands, and the southern
shoreline of the Alaska Peninsula. Although most carcasses have been
non-retrievable as they were discovered floating and in a state of
moderate to severe decomposition, the UME is likely attributable to
ecological factors, i.e., the 2015 El Ni[ntilde]o, ``warm water blob,''
and the Pacific Coast domoic acid bloom. The UME was closed in 2016.
More information is available online at <a href="http://www.fisheries.noaa.gov/national/marine-life-distress/2015-2016-large-whale-unusual-mortality-event-western-gulf-alaska">www.fisheries.noaa.gov/national/marine-life-distress/2015-2016-large-whale-unusual-mortality-event-western-gulf-alaska</a>.
Marine Mammal Hearing
Hearing is the most important sensory modality for marine mammals
[[Page 30015]]
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. Current data indicate that 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) recommended that marine mammals be divided
into functional hearing groups based on directly measured or estimated
hearing ranges on the basis of available behavioral response data,
audiograms derived using auditory evoked potential techniques,
anatomical modeling, and other data. 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 (dolphins, 150 Hz to 160 kHz.
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) (true 50 Hz to 86 kHz.
seals).
Otariid pinnipeds (OW) (underwater) (sea 60 Hz to 39 kHz.
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 and Holt,
2013).
For more detail concerning these groups and associated frequency
ranges, please see NMFS (2018) for a review of available information.
Twenty-one marine mammal species (16 cetacean and 5 pinniped (3 otariid
and 2 phocid) species) are considered herein. Of the cetacean species
that may be present, six are classified as low-frequency cetaceans
(i.e., all mysticete species), eight are classified as mid-frequency
cetaceans (i.e., all delphinid and ziphiid species and the sperm
whale), and two are classified as high-frequency cetaceans (i.e.,
porpoises).
Potential Effects of Specified Activities on Marine Mammals and Their
Habitat
This section includes a summary of the ways that L-DEO's specified
activity may impact marine mammals and their habitat. Detailed
descriptions of the potential effects of similar specified activities
have been provided in other recent Federal Register notices, including
for survey activities using the same methodology and over a similar
amount of time, and affecting similar species (e.g., 83 FR 29212, June
22, 2018; 84 FR 14200, April 9, 2019; 85 FR 19580, April 7, 2020). No
significant new information is available, and we refer the reader to
these documents for additional detail. The Estimated Take section
includes a quantitative analysis of the number of individuals that are
expected to be taken by L-DEO's activity. The Negligible Impact
Analysis and Determination section considers the potential effects of
the specified activity, the Estimated Take 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 how those impacts on individuals are likely to impact
marine mammal species or stocks.
Background on Active Acoustic Sound Sources and Acoustic Terminology
This section contains a brief technical background on sound, on the
characteristics of certain sound types, and on metrics used in this
proposal inasmuch as the information is relevant to the specified
activity and to the discussion of the effects of the specified activity
on marine mammals in this document. For general information on sound
and its interaction with the marine environment, please see, e.g., Au
and Hastings (2008); Richardson et al. (1995); Urick (1983).
Sound travels in waves, the basic components of which are
frequency, wavelength, velocity, and amplitude. Frequency is the number
of pressure waves that pass by a reference point per unit of time and
is measured in hertz or cycles per second. Wavelength is the distance
between two peaks or corresponding points of a sound wave (length of
one cycle). Higher frequency sounds have shorter wavelengths than lower
frequency sounds, and typically attenuate (decrease) more rapidly,
except in certain cases in shallower water. Amplitude is the height of
the sound pressure wave or the ``loudness'' of a sound and is typically
described using the relative unit of the decibel. A sound pressure
level (SPL) in dB is described as the ratio between a measured pressure
and a reference pressure (for underwater sound, this is 1 microPascal
([mu]Pa)), and is a logarithmic unit that accounts for large variations
in amplitude. Therefore, a relatively small change in dB corresponds to
large changes in sound pressure. The source level (SL) represents the
SPL referenced at a distance of 1 m from the source (referenced to 1
[mu]Pa), while the received level is the SPL at the listener's position
(referenced to 1 [mu]Pa).
Root mean square (rms) is the quadratic mean sound pressure over
the duration of an impulse. Root mean square is calculated by squaring
all of the sound amplitudes, averaging the squares, and then taking the
square root of the average (Urick, 1983). Root mean square accounts for
both positive and negative values; squaring the pressures makes all
values positive so that they
[[Page 30016]]
may be accounted for in the summation of pressure levels (Hastings and
Popper, 2005). This measurement is often used in the context of
discussing behavioral effects, in part because behavioral effects,
which often result from auditory cues, may be better expressed through
averaged units than by peak pressures.
Sound exposure level (SEL; represented as dB re 1 [mu]Pa2-s)
represents the total energy in a stated frequency band over a stated
time interval or event and considers both intensity and duration of
exposure. The per-pulse SEL is calculated over the time window
containing the entire pulse (i.e., 100 percent of the acoustic energy).
SEL is a cumulative metric; it can be accumulated over a single pulse,
or calculated over periods containing multiple pulses. Cumulative SEL
represents the total energy accumulated by a receiver over a defined
time window or during an event. Peak sound pressure (also referred to
as zero-to-peak sound pressure or 0-pk) is the maximum instantaneous
sound pressure measurable in the water at a specified distance from the
source and is represented in the same units as the rms sound pressure.
When underwater objects vibrate or activity occurs, sound-pressure
waves are created. These waves alternately compress and decompress the
water as the sound wave travels. Underwater sound waves radiate in a
manner similar to ripples on the surface of a pond and may be either
directed in a beam or beams or may radiate in all directions
(omnidirectional sources), as is the case for sound produced by the
pile driving activity considered here. The compressions and
decompressions associated with sound waves are detected as changes in
pressure by aquatic life and man-made sound receptors such as
hydrophones.
Even in the absence of sound from the specified activity, the
underwater environment is typically loud due to ambient sound, which is
defined as environmental background sound levels lacking a single
source or point (Richardson et al., 1995). The sound level of a region
is defined by the total acoustical energy being generated by known and
unknown sources. These sources may include physical (e.g., wind and
waves, earthquakes, ice, atmospheric sound), biological (e.g., sounds
produced by marine mammals, fish, and invertebrates), and anthropogenic
(e.g., vessels, dredging, construction) sound. A number of sources
contribute to ambient sound, including wind and waves, which are a main
source of naturally occurring ambient sound for frequencies between 200
hertz (Hz) and 50 kilohertz (kHz) (Mitson, 1995). In general, ambient
sound levels tend to increase with increasing wind speed and wave
height. Precipitation can become an important component of total sound
at frequencies above 500 Hz, and possibly down to 100 Hz during quiet
times. Marine mammals can contribute significantly to ambient sound
levels, as can some fish and snapping shrimp. The frequency band for
biological contributions is from approximately 12 Hz to over 100 kHz.
Sources of ambient sound related to human activity include
transportation (surface vessels), dredging and construction, oil and
gas drilling and production, geophysical surveys, sonar, and
explosions. Vessel noise typically dominates the total ambient sound
for frequencies between 20 and 300 Hz. In general, the frequencies of
anthropogenic sounds are below 1 kHz and, if higher frequency sound
levels are created, they attenuate rapidly.
The sum of the various natural and anthropogenic sound sources that
comprise ambient sound at any given location and time depends not only
on the source levels (as determined by current weather conditions and
levels of biological and human 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. Details of source types are described in the following text.
Sounds are often considered to fall into one of two general types:
Pulsed and non-pulsed (defined in the following). The distinction
between these two sound types is important because they have differing
potential to cause physical effects, particularly with regard to
hearing (e.g., Ward, 1997 in Southall et al., 2007). Please see
Southall et al. (2007) for an in-depth discussion of these concepts.
The distinction between these two sound types is not always obvious, as
certain signals share properties of both pulsed and non-pulsed sounds.
A signal near a source could be categorized as a pulse, but due to
propagation effects as it moves farther from the source, the signal
duration becomes longer (e.g., Greene and Richardson, 1988).
Pulsed sound sources (e.g., airguns, explosions, gunshots, sonic
booms, impact pile driving) produce signals that are brief (typically
considered to be less than one second), broadband, atonal transients
(ANSI, 1986, 2005; Harris, 1998; NIOSH, 1998; ISO, 2003) and occur
either as isolated events or repeated in some succession. Pulsed 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-pulsed sounds can be tonal, narrowband, or broadband, brief or
prolonged, and may be either continuous or intermittent (ANSI, 1995;
NIOSH, 1998). Some of these non-pulsed sounds can be transient signals
of short duration but without the essential properties of pulses (e.g.,
rapid rise time). Examples of non-pulsed sounds include those produced
by vessels, aircraft, machinery operations such as 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.
Airgun arrays produce pulsed signals with energy in a frequency
range from about 10-2,000 Hz, with most energy radiated at frequencies
below 200 Hz. The amplitude of the acoustic wave emitted from the
source is equal in all directions (i.e., omnidirectional), but airgun
arrays do possess some directionality due to different phase delays
between guns in different directions. Airgun arrays are typically tuned
to maximize functionality for data acquisition purposes, meaning that
sound transmitted in horizontal directions and at higher frequencies is
minimized to the extent possible.
Summary on Specific Potential Effects of Acoustic Sound Sources
Underwater sound from active acoustic sources can include one or
more of the following: Temporary or permanent hearing impairment, non-
auditory physical or physiological effects, behavioral disturbance,
stress, and masking. The degree of effect is intrinsically related to
the signal characteristics, received level, distance from the source,
and duration of the
[[Page 30017]]
sound exposure. Marine mammals exposed to high-intensity sound, or to
lower-intensity sound for prolonged periods, can experience hearing
threshold shift (TS), which is the loss of hearing sensitivity at
certain frequency ranges (Finneran, 2015). TS can be permanent (PTS),
in which case the loss of hearing sensitivity is not fully recoverable,
or temporary (TTS), in which case the animal's hearing threshold would
recover over time (Southall et al., 2007).
Due to the characteristics of airgun arrays as a distributed sound
source, maximum estimated Level A harassment isopleths for species of
certain hearing groups are assumed to fall within the near field of the
array. For these species, i.e., mid-frequency cetaceans and all
pinnipeds, animals in the vicinity of L-DEO's proposed seismic survey
activity are unlikely to incur PTS. For low-frequency cetaceans and
high-frequency cetaceans, potential exposures sufficient to cause low-
level PTS may occur on the basis of cumulative exposure level and
instantaneous exposure to peak pressure levels, respectively. However,
when considered in conjunction with the potential for aversive
behavior, relative motion of the exposed animal and the sound source,
and the anticipated efficacy of the proposed mitigation requirements, a
reasonable conclusion may be drawn that PTS is not a likely outcome for
any species. However, we propose to authorize take by Level A
harassment, where indicated by the quantitative exposure analysis, for
species from the low- and high-frequency cetacean hearing groups.
Please see Estimated Take and Proposed Mitigation for further
discussion.
Behavioral disturbance may include a variety of effects, including
subtle changes in behavior (e.g., minor or brief avoidance of an area
or changes 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 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. 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.
In addition, sound can disrupt behavior through masking, or
interfering 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). Masking occurs when the receipt of a
sound is interfered with by another coincident sound at similar
frequencies and at similar or higher intensity, and may occur whether
the sound is natural (e.g., snapping shrimp, wind, waves,
precipitation) or anthropogenic (e.g., shipping, sonar, seismic
exploration) in origin.
Sound may affect marine mammals through impacts on the abundance,
behavior, or distribution of prey species (e.g., crustaceans,
cephalopods, fish, zooplankton) (i.e., effects to marine mammal
habitat). Prey species exposed to sound might move away from the sound
source, experience TTS, experience masking of biologically relevant
sounds, or show no obvious direct effects. The most likely impacts (if
any) for most prey species in a given area would be temporary avoidance
of the area. Surveys using active acoustic sound sources move through
an area relatively quickly, limiting exposure to multiple pulses. In
all cases, sound levels would return to ambient once a survey ends and
the noise source is shut down and, when exposure to sound ends,
behavioral and/or physiological responses are expected to end
relatively quickly. Finally, the survey equipment will not have
significant impacts to the seafloor and does not represent a source of
pollution.
Vessel Strike
Vessel collisions with marine mammals, or ship strikes, can result
in death or serious injury of the animal. These interactions are
typically associated with large whales, which are less maneuverable
than are smaller cetaceans or pinnipeds in relation to large vessels.
The severity of injuries typically depends on the size and speed of the
vessel, with the probability of death or serious injury increasing as
vessel speed increases (Knowlton and Kraus, 2001; Laist et al., 2001;
Vanderlaan and Taggart, 2007; Conn and Silber, 2013). Impact forces
increase with speed, as does the probability of a strike at a given
distance (Silber et al., 2010; Gende et al., 2011). The chances of a
lethal injury decline from approximately 80 percent at 15 kn to
approximately 20 percent at 8.6 kn. At speeds below 11.8 kn, the
chances of lethal injury drop below 50 percent (Vanderlaan and Taggart,
2007).
Ship strikes generally involve commercial shipping, which is much
more common in both space and time than is geophysical survey activity
and which typically involves larger vessels moving at faster speeds.
Jensen and Silber (2004) summarized ship strikes of large whales
worldwide from 1975-2003 and found that most collisions occurred in the
open ocean and involved large vessels (e.g., commercial shipping).
Commercial fishing vessels were responsible for 3 percent of recorded
collisions, while no such incidents were reported for geophysical
survey vessels during that time period.
For vessels used in geophysical survey activities, vessel speed
while towing gear is typically only 4-5 kn. At these speeds, both the
possibility of striking a marine mammal and the possibility of a strike
resulting in serious injury or mortality are so low as to be
discountable. At average transit speed for geophysical survey vessels
(approximately 10 kn), the probability of serious injury or mortality
resulting from a strike (if it occurred) is less than 50 percent
(Vanderlaan and Taggart, 2007; Conn and Silber, 2013). However, the
likelihood of a strike actually happening is again low given the
smaller size of these vessels and generally slower speeds. We
anticipate that vessel collisions involving seismic data acquisition
vessels towing gear, while not impossible, represent unlikely,
unpredictable events for which there are no preventive measures. Given
the required mitigation measures, the relatively slow speeds of vessels
towing gear, the presence of bridge crew watching for obstacles at all
times (including marine mammals), the presence of marine mammal
observers, and the small number of seismic survey cruises relative to
commercial ship traffic, we believe that the possibility of ship strike
is discountable and, further, that were a strike of a large whale to
occur, it would be unlikely to result in serious injury or mortality.
No incidental take resulting from ship strike is anticipated or
proposed for authorization, and this potential effect of the specified
activity will not be discussed further in the following analysis.
The potential effects of L-DEO's specified survey activity are
expected to be limited to Level B harassment consisting of behavioral
harassment and/or temporary auditory effects and, for certain species
of low- and high-frequency cetaceans only, low-level permanent auditory
effects. No permanent auditory effects for any species belonging to
other hearing groups, or significant impacts to marine
[[Page 30018]]
mammal habitat, including prey, are expected.
Estimated Take
This section provides an estimate of the number of incidental takes
proposed for authorization through this IHA, which will inform both
NMFS' consideration of ``small numbers'' and the negligible impact
determination.
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 seismic airguns has the potential to result in disruption of
behavioral patterns or temporary auditory effects for individual marine
mammals. There is also some potential for auditory injury (Level A
harassment) for low-frequency (i.e., mysticetes) and high-frequency
cetaceans (i.e., porpoises). The proposed mitigation and monitoring
measures are expected to minimize the severity of such 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 take is estimated.
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)
and the number of days of activities. We note that while these basic
factors can contribute to a basic calculation to provide an initial
prediction of 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
estimate.
Acoustic Thresholds
NMFS uses 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).
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 (e.g., frequency, predictability, duty cycle), the environment
(e.g., bathymetry), and the receiving animals (hearing, motivation,
experience, demography, behavioral context) and can be difficult to
predict (Southall et al., 2007, Ellison et al., 2012). NMFS uses a
generalized acoustic threshold based on received level to estimate the
onset of behavioral harassment. NMFS predicts that marine mammals may
be behaviorally harassed (i.e., Level B harassment) when exposed to
underwater anthropogenic noise above received levels of 160 dB re 1
[mu]Pa (rms) for the impulsive sources (i.e., seismic airguns)
evaluated here.
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 or non-impulsive). L-DEO's
proposed seismic survey includes the use of impulsive (seismic airguns)
sources.
These thresholds are provided in the table 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>.
Table 3--Thresholds Identifying the Onset of Permanent Threshold Shift
----------------------------------------------------------------------------------------------------------------
PTS onset acoustic thresholds * (received level)
----------------------------------------------------------------------------------------------------------------
Hearing group Impulsive Non-impulsive
----------------------------------------------------------------------------------------------------------------
Low-Frequency (LF) Cetaceans........... Cell 1: Lpk,flat: 219 dB; Cell 2: L,E,LF,24h: 199 dB.
L,E,LF,24h: 183 dB.
Mid-Frequency (MF) Cetaceans........... Cell 3: Lpk,flat: 230 dB; Cell 4: L,E,MF,24h: 198 dB.
L,E,MF,24h: 185 dB.
High-Frequency (HF) Cetaceans.......... Cell 5: Lpk,flat: 202 dB; Cell 6: L,E,HF,24h: 173 dB.
L,E,HF,24h: 155 dB.
Phocid Pinnipeds (PW) (Underwater)..... Cell 7: Lpk,flat: 218 dB; Cell 8: L,E,PW,24h: 201 dB.
L,E,PW,24h: 185 dB.
Otariid Pinnipeds (OW) (Underwater).... Cell 9: Lpk,flat: 232 dB; Cell 10: L,E,OW,24h: 219 dB.
L,E,OW,24h: 203 dB.
----------------------------------------------------------------------------------------------------------------
* Dual metric acoustic thresholds for impulsive sounds: Use whichever results in the largest isopleth for
calculating PTS onset. If a non-impulsive sound has the potential of exceeding the peak sound pressure level
thresholds associated with impulsive sounds, these thresholds should also be considered.
Note: Peak sound pressure (Lpk) has a reference value of 1 [mu]Pa, and cumulative sound exposure level (LE) has
a reference value of 1[mu]Pa\2\s. In this Table, thresholds are abbreviated to reflect American National
Standards Institute standards (ANSI 2013). However, peak sound pressure is defined by ANSI 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 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.
Ensonified Area
Here, we describe operational and environmental parameters of the
activity and other relevant information that will feed into identifying
the area ensonified above the acoustic thresholds.
L-DEO's modeling methodologies are described in greater detail in
Appendix A of L-DEO's IHA application. The proposed 2D survey would
acquire data using the 36-airgun array with a total discharge volume of
6,600 in\3\ at a maximum tow depth of 12 m. L-DEO's modeling approach
uses ray tracing for
[[Page 30019]]
the direct wave traveling from the array to the receiver and its
associated source ghost (reflection at the air-water interface in the
vicinity of the array), in a constant-velocity half-space (infinite
homogeneous ocean layer, unbounded by a seafloor). To validate the
model results, L-DEO measured propagation of pulses from the 36-airgun
array at a tow depth of 6 m in the Gulf of Mexico, for deep water
(~1,600 m), intermediate water depth on the slope (~600-1,100 m), and
shallow water (~50 m) (Tolstoy et al., 2009; Diebold et al., 2010).
L-DEO collected a MCS data set from R/V Langseth (array towed at 9
m depth) on an 8-km streamer in 2012 on the shelf of the Cascadia
Margin off of Washington in water up to 200 m deep that allowed Crone
et al. (2014) to analyze the hydrophone streamer data (>1,100
individual shots). These empirical data were then analyzed to determine
in situ sound levels for shallow and upper intermediate water depths.
These data suggest that modeled radii were 2-3 times larger than the
measured radii in shallow water. Similarly, data collected by Crone et
al. (2017) during a survey off New Jersey in 2014 and 2015 confirmed
that in situ measurements collected by the R/V Langseth hydrophone
streamer were 2-3 times smaller than the predicted radii.
L-DEO model results are used to determine the assumed radial
distance to the 160-dB rms threshold for these arrays in deep water
(>1,000 m) (down to a maximum water depth of 2,000 m). Water depths in
the project area may be up to 2,800 m, but marine mammals in the region
are generally not anticipated to dive below 2,000 m (e.g., Costa and
Williams, 1999). L-DEO typically derives estimated distances for
intermediate water depths by applying a correction factor of 1.5 to the
model results for deep water. In this case, the estimated radial
distance for intermediate (100-1,000 m) and shallow (<100 m) water
depths is taken from Crone et al. (2014), as these empirical data were
collected in the same region as this proposed survey. A correction
factor of 1.15 was applied to account for differences in array tow
depth.
The estimated distances to the Level B harassment isopleths for the
array are shown in Table 4.
Table 4--Predicted Radial Distances to Isopleths Corresponding to Level B Harassment Threshold
----------------------------------------------------------------------------------------------------------------
Level B
Source and volume Tow depth (m) Water depth harassment
(m) zone (m)
----------------------------------------------------------------------------------------------------------------
36 airgun array; 6,600 in\3\.................................... 12 >1000 \1\ 6,733
100-1000 \2\ 9,468
<100 \2\ 12,650
----------------------------------------------------------------------------------------------------------------
\1\ Distance based on L-DEO model results.
\2\ Based on empirical data from Crone et al. (2014) with scaling.
Predicted distances to Level A harassment isopleths, which vary
based on marine mammal hearing groups, were calculated based on
modeling performed by L-DEO using the NUCLEUS source modeling software
program and the NMFS User Spreadsheet, described below. The acoustic
thresholds for impulsive sounds (e.g., airguns) contained in the
Technical Guidance were presented as dual metric acoustic thresholds
using both SEL<INF>cum</INF> and peak sound pressure metrics (NMFS
2018). As dual metrics, NMFS considers onset of PTS (Level A
harassment) to have occurred when either one of the two metrics is
exceeded (i.e., metric resulting in the largest isopleth). The
SEL<INF>cum</INF> metric considers both level and duration of exposure,
as well as auditory weighting functions by marine mammal hearing group.
In recognition of the fact that the requirement to calculate Level A
harassment ensonified areas could be more technically challenging to
predict due to the duration component and the use of weighting
functions in the new SEL<INF>cum</INF> thresholds, NMFS developed an
optional User Spreadsheet that includes tools to help predict a simple
isopleth that can be used in conjunction with marine mammal density or
occurrence to facilitate the estimation of take numbers.
The values for SEL<INF>cum</INF> and peak SPL for the Langseth
airgun arrays were derived from calculating the modified far-field
signature. The farfield signature is often used as a theoretical
representation of the source level. To compute the farfield signature,
the source level is estimated at a large distance below the array
(e.g., 9 km), and this level is back projected mathematically to a
notional distance of 1 m from the array's geometrical center. However,
when the source is an array of multiple airguns separated in space, the
source level from the theoretical farfield signature is not necessarily
the best measurement of the source level that is physically achieved at
the source (Tolstoy et al., 2009). Near the source (at short ranges,
distances <1 km), the pulses of sound pressure from each individual
airgun in the source array do not stack constructively, as they do for
the theoretical farfield signature. The pulses from the different
airguns spread out in time such that the source levels observed or
modeled are the result of the summation of pulses from a few airguns,
not the full array (Tolstoy et al., 2009). At larger distances, away
from the source array center, sound pressure of all the airguns in the
array stack coherently, but not within one time sample, resulting in
smaller source levels (a few dB) than the source level derived from the
farfield signature. Because the farfield signature does not take into
account the large array effect near the source and is calculated as a
point source, the modified farfield signature is a more appropriate
measure of the sound source level for distributed sound sources, such
as airgun arrays. L-DEO used the acoustic modeling methodology as used
for estimating Level B harassment distances with a small grid step of 1
m in both the inline and depth directions. The propagation modeling
takes into account all airgun interactions at short distances from the
source, including interactions between subarrays, which are modeled
using the NUCLEUS software to estimate the notional signature and
MATLAB software to calculate the pressure signal at each mesh point of
a grid.
In order to more realistically incorporate the Technical Guidance's
weighting functions over the seismic array's full acoustic band,
unweighted spectrum data for the Langseth's airgun array (modeled in 1
Hz bands) was used to make adjustments (dB) to the unweighted spectrum
levels, by frequency, according to the weighting functions for each
relevant marine mammal hearing group. These adjusted/weighted spectrum
levels were then converted to pressures ([mu]Pa) in order to integrate
them over the entire
[[Page 30020]]
broadband spectrum, resulting in broadband weighted source levels by
hearing group that could be directly incorporated within the User
Spreadsheet (i.e., to override the Spreadsheet's more simple weighting
factor adjustment). Using the User Spreadsheet's ``safe distance''
methodology for mobile sources (described by Sivle et al., 2014) with
the hearing group-specific weighted source levels, and inputs assuming
spherical spreading propagation and information specific to the planned
survey (i.e., the 2.2 m/s source velocity and (worst-case) 23-s shot
interval), potential radial distances to auditory injury zones were
then calculated for SEL<INF>cum</INF> thresholds.
Inputs to the User Spreadsheets in the form of estimated source
levels are shown in Appendix A of L-DEO's application. User
Spreadsheets used by L-DEO to estimate distances to Level A harassment
isopleths for the airgun arrays are also provided in Appendix A of the
application. Outputs from the User Spreadsheets in the form of
estimated distances to Level A harassment isopleths for the survey are
shown in Table 5. As described above, NMFS considers onset of PTS
(Level A harassment) to have occurred when either one of the dual
metrics (SEL<INF>cum</INF> and Peak SPL<INF>flat</INF>) is exceeded
(i.e., metric resulting in the largest isopleth).
Table 5--Modeled Radial Distances (m) to Isopleths Corresponding to Level A Harassment Thresholds
----------------------------------------------------------------------------------------------------------------
Level A harassment zone (m)
-------------------------------------------------------------------
Source (volume) Threshold HF
LF cetaceans MF cetaceans cetaceans Phocids Otariids
----------------------------------------------------------------------------------------------------------------
36-airgun array (6,600 SELcum........ 320 0 1 10 0
in\3\).
Peak.......... 39 14 268 44 11
----------------------------------------------------------------------------------------------------------------
Note that because of some of the assumptions included in the
methods used (e.g., stationary receiver with no vertical or horizontal
movement in response to the acoustic source), isopleths produced may be
overestimates to some degree, which will ultimately result in some
degree of overestimation of Level A harassment. However, these tools
offer the best way to predict appropriate isopleths when more
sophisticated modeling methods are not available, and NMFS continues to
develop ways to quantitatively refine these tools and will
qualitatively address the output where appropriate. For mobile sources,
such as the proposed seismic survey, the User Spreadsheet predicts the
closest distance at which a stationary animal would not incur PTS if
the sound source traveled by the animal in a straight line at a
constant speed.
Auditory injury is unlikely to occur for mid-frequency cetaceans,
otariid pinnipeds, and phocid pinnipeds given very small modeled zones
of injury for those species (all estimated zones less than 15 m for
mid-frequency cetaceans and otariid pinnipeds, up to a maximum of 44 m
for phocid pinnipeds), in context of distributed source dynamics. The
source level of the array is a theoretical definition assuming a point
source and measurement in the far-field of the source (MacGillivray,
2006). As described by Caldwell and Dragoset (2000), an array is not a
point source, but one that spans a small area. In the far-field,
individual elements in arrays will effectively work as one source
because individual pressure peaks will have coalesced into one
relatively broad pulse. The array can then be considered a ``point
source.'' For distances within the near-field, i.e., approximately 2-3
times the array dimensions, pressure peaks from individual elements do
not arrive simultaneously because the observation point is not
equidistant from each element. The effect is destructive interference
of the outputs of each element, so that peak pressures in the near-
field will be significantly lower than the output of the largest
individual element. Here, the relevant peak isopleth distances would in
all cases be expected to be within the near-field of the array where
the definition of source level breaks down. Therefore, actual locations
within this distance of the array center where the sound level exceeds
the relevant peak SPL thresholds would not necessarily exist. In
general, Caldwell and Dragoset (2000) suggest that the near-field for
airgun arrays is considered to extend out to approximately 250 m.
In order to provide quantitative support for this theoretical
argument, we calculated expected maximum distances at which the near-
field would transition to the far-field (Table 5). For a specific array
one can estimate the distance at which the near-field transitions to
the far-field by:
[GRAPHIC] [TIFF OMITTED] TN04JN21.004
with the condition that D >> [lambda], and where D is the distance, L
is the longest dimension of the array, and [lambda] is the wavelength
of the signal (Lurton, 2002). Given that [lambda] can be defined by:
[GRAPHIC] [TIFF OMITTED] TN04JN21.005
where f is the frequency of the sound signal and v is the speed of the
sound in the medium of interest, one can rewrite the equation for D as:
[GRAPHIC] [TIFF OMITTED] TN04JN21.006
and calculate D directly given a particular frequency and known speed
of sound (here assumed to be 1,500 meters per second in water, although
this varies with environmental conditions).
To determine the closest distance to the arrays at which the source
level predictions in Table 5 are valid (i.e., maximum extent of the
near-field), we calculated D based on an assumed frequency of 1 kHz. A
frequency of 1 kHz is commonly used in near-field/far-field
calculations for airgun arrays (Zykov and Carr, 2014; MacGillivray,
2006; NSF and USGS, 2011), and based on representative airgun spectrum
data and field measurements of an airgun array used on the Langseth,
nearly all (greater than 95 percent) of the energy from airgun arrays
is below 1 kHz (Tolstoy et al., 2009). Thus, using 1 kHz as the upper
cut-off for calculating the maximum extent of the near-field should
reasonably represent the near-field extent in field conditions.
If the largest distance to the peak sound pressure level threshold
was equal to or less than the longest dimension of the array (i.e.,
under the array), or within the near-field, then received levels that
meet or exceed the threshold in most cases are not expected to occur.
This is because within the near-field and within the dimensions of the
array, the source levels specified in Appendix A of L-DEO's application
are
[[Page 30021]]
overestimated and not applicable. In fact, until one reaches a distance
of approximately three or four times the near-field distance the
average intensity of sound at any given distance from the array is
still less than that based on calculations that assume a directional
point source (Lurton, 2002). The 6,600-in\3\ airgun array planned for
use during the proposed survey has an approximate diagonal of 28.8 m,
resulting in a near-field distance of 138.7 m at 1 kHz (NSF and USGS,
2011). Field measurements of this array indicate that the source
behaves like multiple discrete sources, rather than a directional point
source, beginning at approximately 400 m (deep site) to 1 km (shallow
site) from the center of the array (Tolstoy et al., 2009), distances
that are actually greater than four times the calculated 140-m near-
field distance. Within these distances, the recorded received levels
were always lower than would be predicted based on calculations that
assume a directional point source, and increasingly so as one moves
closer towards the array (Tolstoy et al., 2009). Given this, relying on
the calculated distance (138.7 m) as the distance at which we expect to
be in the near-field is a conservative approach since even beyond this
distance the acoustic modeling still overestimates the actual received
level. Within the near-field, in order to explicitly evaluate the
likelihood of exceeding any particular acoustic threshold, one would
need to consider the exact position of the animal, its relationship to
individual array elements, and how the individual acoustic sources
propagate and their acoustic fields interact. Given that within the
near-field and dimensions of the array source levels would be below
those assumed here, we believe exceedance of the peak pressure
threshold would only be possible under highly unlikely circumstances.
In consideration of the received sound levels in the near-field as
described above, we expect the potential for Level A harassment of mid-
frequency cetaceans, otariid pinnipeds, and phocid pinnipeds to be de
minimis, even before the likely moderating effects of aversion and/or
other compensatory behaviors (e.g., Nachtigall et al., 2018) are
considered. We do not believe that Level A harassment is a likely
outcome for any mid-frequency cetacean, otariid pinniped, or phocid
pinniped and do not propose to authorize any Level A harassment for
these species.
Marine Mammal Occurrence
In this section we provide the information about the presence,
density, and group dynamics of marine mammals that will inform the take
calculations. The Navy's Marine Species Density Database (DoN, 2019,
2021) is currently the most comprehensive compendium for density data
available for the Gulf of Alaska (GOA) and is the only source of
density data available for southeast Alaska. Habitat-based stratified
marine mammal densities developed by the U.S. Navy for assessing
potential impacts of training activities in the GOA (DoN, 2021; Rone et
al., 2014, 2017) and at Behm Canal in southeast Alaska (DoN, 2019)
represent the best available information for estimating potential
marine mammal exposures. The Navy's GOA Temporary Marine Activities
Area (TMAA) is situated south of Prince William Sound and east of
Kodiak Island. The northern boundary of the TMAA is approximately 24
nautical miles south of the Kenai Peninsula. Behm Canal is
approximately 45 km east of Ketchikan, AK, inshore of the proposed
survey area in the same general part of southeast Alaska. In general,
GOA density values were used for offshore (deep water depths) portions
of the survey area, and Behm Canal density values were used for inshore
(shallow and intermediate water depths) portions. For some species, no
Behm Canal density information is available, and the GOA density value
was applied to all water depths. Density values are provided in Table 6
and discussed in greater detail below.
Table 6--Estimated Density Values by Water Depth
[#/km2]
----------------------------------------------------------------------------------------------------------------
Intermediate Deep depth
Species Shallow depth depth (100-1,000 (>1,000 m) 1
(<100 m) 1 m) 1
----------------------------------------------------------------------------------------------------------------
Gray whale \4\.............................................. 0.0486 0.0486 0
Humpback whale.............................................. \3\ 0.0117 \3\ 0.0117 \4\ 0.0010
Blue whale \4\.............................................. 0.0001 0.0001 0.0005
Fin whale................................................... \3\ 0.0001 \3\ 0.0001 \4\ 0.0160
Sei whale \4\............................................... 0.0004 0.0004 0.0004
Minke whale................................................. \3\ 0.0008 \3\ 0.0008 \4\ 0.0006
Sperm whale \4\............................................. 0 0.0020 0.0013
Baird's beaked whale \4\.................................... 0 0 0.0005
Stejneger's beaked whale \4\................................ 0 0 0.0021
Cuvier's beaked whale \4\................................... 0 0 0.0020
Pacific white-sided dolphin................................. \3\ 0.0075 \3\ 0.0075 \4\ 0.0200
Northern right whale dolphin \5\............................ 0.0110 0.0276 0.0367
Risso's dolphin \2\......................................... 0.0000 0.0000 0.0000
Killer whale................................................ \3\ 0.0057 \3\ 0.0057 \4\ 0.0020
Dall's porpoise............................................. \3\ 0.1210 \3\ 0.1210 \4\ 0.0370
Harbor porpoise \6\......................................... 0.0330 0.0330 0
Northern fur seal \4\....................................... 0.0661 0.0661 0.0661
California sea lion \3\..................................... 0.0288 0.0288 0.0065
Steller sea lion............................................ \3\ 0.3162 \4\ 0.0570 0
Northern elephant seal \4\.................................. 0.0779 0.0779 0.0779
Harbor seal................................................. \3\ 0.7811 \4\ 0.1407 0
----------------------------------------------------------------------------------------------------------------
\1\ A zero value indicates the species is not expected to occur in that depth stratum.
\2\ Nominal density value of 0.00001 applied to Risso's dolphin.
\3\ Source: DoN, 2019; \4\ Source DoN, 2021; \5\ Source: Becker et al. (2016); \6\ Hobbs and Waite (2010).
[[Page 30022]]
The Navy conducted comprehensive marine mammal surveys in theTMAA
in 2009 and 2013. Additional survey effort was conducted in 2015. These
surveys used systematic line-transect survey protocols including visual
and acoustic detection methods (Rone et al., 2010, 2014, 2017). The
data were collected in four strata that were designed to encompass the
four distinct habitats within the TMAA and greater GOA: Inshore: All
waters <1,000 m deep; Slope: From 1,000 m water depth to the Aleutian
trench/subduction zone; Offshore: Waters offshore of the Aleutian
trench/subduction zone; Seamount: Waters within defined seamount areas.
Density values for the slope and seamount regions of the TMAA are not
relevant for the survey area considered herein. There were insufficient
sightings data from the 2009, 2013, and 2015 line-transect surveys to
calculate reliable density estimates for certain cetacean species in
the GOA. In these cases, other available information supported
development of density estimates. Additional sources of information
include summer 2003 cetacean surveys near the Kenai Peninsula, within
Prince William Sound and around Kodiak Island (Waite, 2003 in DoN,
2021), summer 2010-2012 line-transect data collected over a broad area
north of 40[deg] N, south of the Aleutian Islands, and between 170[deg]
E and 135[deg] W during the International Whaling Commission-Pacific
Ocean Whale and Ecosystem Research cruises (Hakamada et al., 2017), and
analysis of acoustic data from the 2013 Navy-funded survey effort in
the TMAA (Yack et al., 2015). See DoN (2021) for additional detail.
When seasonal densities were available, the calculated exposures were
based on summer densities, which are most representative of the
proposed survey timing.
Pinniped numbers are commonly assessed by counting individuals at
haul-outs or the number of pups weaned at rookeries. Translating these
numbers to in-water densities presents challenges unique to pinnipeds.
No in-water line transect survey data were available for harbor seal,
Steller sea lion, or California sea lion in the GOA. Surveys conducted
by Rone et al. (2014) recorded sightings of northern elephant seal and
northern fur seal in the TMAA; however, these data were insufficient to
estimate a density for northern elephant seal, and were not used for
northern fur seal due to the availability of more recent data. To
account for the lack of in-water survey data for pinnipeds, published
abundance estimates used in the density calculations were adjusted
using a species-specific haul-out factor to estimate an in-water
abundance for each species based on haul-out behavior. The calculated
in-water abundance and an area of distribution specific to each species
was used to estimate a density. See DoN (2021) for additional
information. For pinnipeds, where monthly density estimates were
available, the highest value from July or August was applied as most
representative of the proposed survey timing.
Due to a lack of sighting data specific to the Behm Canal area, the
Navy derived density estimates based on data collected from various
surveys (cetaceans) and shore counts (pinnipeds) conducted within
southeast Alaska and GOA. Pinniped density estimates for the Behm Canal
region were additionally derived from publications, NMFS SARs, and
consultation with subject matter experts (DoN, 2019). Systematic ship
surveys conducted in southeast Alaska waters from 1991 to 2012 provided
data to develop stratified line-transect density estimates for harbor
porpoise and Dall's porpoise in regions overlapping a portion of the
Behm Canal area (Dahlheim et al., 2015). Density information for the
Behm Canal area is available for the following species: Minke whale,
fin whale, humpback whale, Pacific white-sided dolphin, killer whale,
harbor porpoise, Dall's porpoise, and for all potentially affected
pinniped species.
The general approach for cetaceans of applying Behm Canal density
estimates to survey effort in shallow and intermediate depth strata and
GOA offshore density estimates to the deep depth stratum was applied
for species for which appropriate estimates were available: Humpback
whale, fin whale, minke whale, Pacific white-sided dolphin, killer
whale, and Dall's porpoise. Note that, for killer whales, Behm Canal
densities are provided specific to transient and resident whales. We
apply the higher transient killer whale density value to estimate
killer whale exposures in shallow and intermediate water depths. Behm
Canal pinniped densities would be expected to overestimate pinniped
occurrence off the coast, and so were not used for intermediate-depth
waters, but were applied to shallow waters where available.
Certain species are not expected to occur in Behm Canal: Gray
whale, blue whale, sei whale, sperm whale, beaked whales, northern fur
seal, and northern elephant seal. For these species, we applied
appropriate GOA density values to all depth strata (i.e., inshore GOA
values to shallow and intermediate water depths and offshore GOA
density values to deep water depths). Note that, while DoN (2021)
provides an inshore density estimate for sperm whales, that stratum
corresponds to water depths <1,000 m. We assume here that sperm whales
do not occur in shallow water depths (<100 m).
Gray whale densities are provided for two zones, nearshore (0-2.25
nmi from shore) and offshore (from 2.25-20 nmi from shore), based on
density information in Carretta et al. (2000) and zones based on data
from Shelden and Laake (2002). DoN (2021) assumes that gray whales do
not occur in the region >20 nmi from shore. The nearshore density is
used here to represent shallow and intermediate water (<1,000 m deep).
This approach assumes a higher density of gray whales across a larger
area and is used as a precautionary approach.
Harbor porpoise densities in DoN (2021) were derived from survey
data collected in summer 1997 in southeast Alaska and 1998 in the Gulf
of Alaska and included correction factors for both perception and
availability bias (Hobbs and Waite, 2010). L-DEO proposed to use
density information from Hobbs and Waite (2010) specific to southeast
Alaska, which better represents the survey area than the GOA
information presented for harbor porpoise in DoN (2021). Following DoN
(2021), we assume harbor porpoise will not occur in deep water (>1,000
m).
No regional density information is available for the northern right
whale dolphin. Becker et al. (2016) used line-transect survey data
collected between 1991 and 2009 to develop predictive habitat-based
models of cetacean densities in the California Current Ecosystem (the
region from Baja California to southern British Columbia). The modeled
density estimates were available on the scale of 7 km by 10 km grid
cells off California, Oregon, and Washington, and values were averaged
for grid cells across Washington and Oregon corresponding with L-DEO's
shallow, intermediate, and deep water survey strata. These density
values were applied to the portion of the survey area off Canada to
calculate estimated exposures, as northern right whale dolphins do not
typically occur beyond the California Current. The Risso's dolphin is
only rarely observed in or near the Navy's GOA survey area, and does
not occur in Behm Canal, so minimal densities were used to represent
their potential presence (DoN, 2021). For California sea lion, density
data is available in DoN (2021); however, it is likely that these
[[Page 30023]]
values would underestimate presence of California sea lions in the
proposed survey area. Therefore, information available in DoN (2019)
for the Offshore Northwest Training and Testing (NWTT) Area (off
Washington/Oregon) in the month of August was used; densities for 0-40
km from shore were applied to shallow and intermediate water depths,
and the density for 0-450 km from shore was used for deep water. The
density for 40-70 km from shore was the lowest and was therefore not
used.
In British Columbia, several systematic surveys have been conducted
in coastal waters (e.g., Williams and Thomas 2007; Ford et al., 2010;
Best et al., 2015; Harvey et al., 2017). Surveys in coastal as well as
offshore waters were conducted by Fisheries and Oceans Canada (DFO)
during 2002 to 2008. However, density estimates for the survey areas
outside the U.S. EEZ, i.e., in the Canadian EEZ, were not readily
available, so density estimates for U.S. waters were applied to the
entire survey area.
Take Calculation and Estimation
Here we describe how the information provided above is brought
together to produce a quantitative take estimate. In order to estimate
the number of marine mammals predicted to be exposed to sound levels
that would result in Level A or Level B harassment, radial distances
from the airgun array to predicted isopleths corresponding to the Level
A harassment and Level B harassment thresholds are calculated, as
described above. Those radial distances are then used to calculate the
area(s) around the airgun array predicted to be ensonified to sound
levels that exceed the Level A and Level B harassment thresholds. The
distance for the 160-dB threshold (based on L-DEO model results) was
used to draw a buffer around every transect line in GIS to determine
the total ensonified area in each depth category. Estimated incidents
of exposure above Level A and Level B harassment criteria are presented
in Table 7. For additional details regarding calculations of ensonified
area, please see Appendix D of L-DEO's application. As noted
previously, L-DEO has added 25 percent in the form of operational days,
which is equivalent to adding 25 percent to the proposed line-kms to be
surveyed. This accounts for the possibility that additional operational
days are required, but likely results in an overestimate of actual
exposures.
As previously noted, NMFS cannot authorize incidental take under
the MMPA that may occur within the territorial seas of foreign nations
(from 0-12 nmi (22.2 km) from shore), as the MMPA does not apply in
those waters. However, NMFS has still calculated the estimated level of
incidental take in the entire activity area (including Canadian
territorial waters) as part of the analysis supporting our
determination under the MMPA that the activity will have a negligible
impact on the affected species. The total estimated take in U.S. and
Canadian waters is presented in Table 8 (see Negligible Impact Analysis
and Determination).
The estimated marine mammal exposures above harassment thresholds
are generally assumed here to equate to take, and the estimates form
the basis for our proposed take authorization numbers. For the species
for which NMFS does not expect there to be a reasonable potential for
take by Level A harassment to occur, i.e., mid-frequency cetaceans and
all pinnipeds, the estimated exposures above Level A harassment
thresholds have been added to the estimated exposures above the Level B
harassment threshold to produce a total number of incidents of take by
Level B harassment that is proposed for authorization. Estimated
exposures and proposed take numbers for authorization are shown in
Table 7. Regarding humpback whale take numbers, we assume that whales
encountered will follow Wade (2017), i.e., that 96.1 percent of takes
would accrue to the Hawaii DPS and 3.8 percent to the Mexico DPS. Of
the estimated take of gray whales, and based on guidance provided
through interagency consultation under section 7 of the ESA, we assume
that 0.1 percent of encountered whales would be from the WNP stock and
propose to authorize take accordingly. For Steller sea lions, 2.2
percent are assumed to belong to the western DPS (Hastings et al.,
2020).
Table 7--Estimated Taking by Level A and Level B Harassment, and Percentage of Population
--------------------------------------------------------------------------------------------------------------------------------------------------------
Estimated Estimated Proposed Proposed
Species Stock 1 Level B Level A Level B Level A Total take Percent of
harassment harassment harassment harassment stock 1
--------------------------------------------------------------------------------------------------------------------------------------------------------
Gray whale................................. WNP.......................... 1,450 45 2 0 2 0.7
ENP.......................... 1,448 45 1,493 5.5
Humpback whale............................. ............................. 403 14 403 14 417 4.1
Blue whale................................. ............................. 31 1 31 1 32 2.1
Fin whale \2\.............................. ............................. 873 44 873 44 917 n/a
Sei whale.................................. ............................. 34 1 34 1 35 6.7
Minke whale \2\............................ ............................. 57 2 57 2 59 n/a
Sperm whale \2\............................ ............................. 131 0 131 0 131 n/a
Baird's beaked whale \2\................... ............................. 29 0 29 0 29 n/a
Stejneger's beaked whale \2\............... ............................. 120 0 120 0 120 n/a
Cuvier's beaked whale \2\.................. ............................. 114 0 114 0 114 n/a
Pacific white-sided dolphin................ ............................. 1,371 3 1,374 0 1,374 5.1
Northern right whale dolphin............... ............................. 922 5 927 0 927 3.5
Risso's dolphin \3\........................ ............................. 1 0 22 0 22 0.3
Killer whale............................... Offshore..................... 290 0 290 0 290 96.7
GOA/BSAI Transient........... 49.4
WC Transient................. 83.1
AK Resident.................. 12.4
Northern Resident............ 96.0
Dall's porpoise............................ ............................. 5,661 178 5,661 178 5,839 7.0
Harbor porpoise............................ ............................. 990 26 990 26 1,016 n/a
Northern fur seal.......................... ............................. 5,804 8 5,812 0 5,812 1.0
California sea lion........................ ............................. 1,256 1 1,258 0 1,258 0.5
Steller sea lion........................... WDPS......................... 2,433 2 54 0 54 0.1
EDPS......................... 2,381 0 2,381 5.5
Northern elephant seal..................... ............................. 6,811 39 6,850 0 6,850 3.8
Harbor seal................................ Sitka/Chatham Strait......... 5,992 21 6,012 0 6,012 45.2
Dixon/Cape Decision.......... 25.6
[[Page 30024]]
Clarence Strait.............. 21.7
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ In most cases, where multiple stocks are being affected, for the purposes of calculating the percentage of the stock impacted, the take is being
analyzed as if all proposed takes occurred within each stock. Where necessary, additional discussion is provided in the Small Numbers section.
\2\ As noted in Table 1, there is no estimate of abundance available for these species.
\3\ Estimated exposure of one Risso's dolphin increased to group size of 22 (Barlow, 2016).
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 (latter not applicable for this action). 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, we
carefully consider 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.
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, impact on
operations, and, in the case of a military readiness activity,
personnel safety, practicality of implementation, and impact on the
effectiveness of the military readiness activity.
In order to satisfy the MMPA's least practicable adverse impact
standard, NMFS has evaluated a suite of basic mitigation protocols for
seismic surveys that are required regardless of the status of a stock.
Additional or enhanced protections may be required for species whose
stocks are in particularly poor health and/or are subject to some
significant additional stressor that lessens that stock's ability to
weather the effects of the specified activities without worsening its
status. We reviewed seismic mitigation protocols required or
recommended elsewhere (e.g., HESS, 1999; DOC, 2013; IBAMA, 2018; Kyhn
et al., 2011; JNCC, 2017; DEWHA, 2008; BOEM, 2016; DFO, 2008; GHFS,
2015; MMOA, 2016; Nowacek et al., 2013; Nowacek and Southall, 2016),
recommendations received during public comment periods for previous
actions, and the available scientific literature. We also considered
recommendations given in a number of review articles (e.g., Weir and
Dolman, 2007; Compton et al., 2008; Parsons et al., 2009; Wright and
Cosentino, 2015; Stone, 2015b). This exhaustive review and
consideration of public comments regarding previous, similar activities
has led to development of the protocols included here.
Vessel-Based Visual Mitigation Monitoring
Visual monitoring requires the use of trained observers (herein
referred to as visual protected species observers (PSOs)) to scan the
ocean surface for the presence of marine mammals. The area to be
scanned visually includes primarily the exclusion zone (EZ), within
which observation of certain marine mammals requires shutdown of the
acoustic source, but also a buffer zone and, to the extent possible
depending on conditions, the surrounding waters. The buffer zone means
an area beyond the EZ to be monitored for the presence of marine
mammals that may enter the EZ. During pre-start clearance monitoring
(i.e., before ramp-up begins), the buffer zone also acts as an
extension of the EZ in that observations of marine mammals within the
buffer zone would also prevent airgun operations from beginning (i.e.,
ramp-up). The buffer zone encompasses the area at and below the sea
surface from the edge of the 0-500 m EZ, out to a radius of 1,000 m
from the edges of the airgun array (500-1,000 m). This 1,000-m zone (EZ
plus buffer) represents the pre-start clearance zone. Visual monitoring
of the EZ and adjacent waters is intended to establish and, when visual
conditions allow, maintain zones around the sound source that are clear
of marine mammals, thereby reducing or eliminating the potential for
injury and minimizing the potential for more severe behavioral
reactions for animals occurring closer to the vessel. Visual monitoring
of the buffer zone is intended to (1) provide additional protection to
na[iuml]ve marine mammals that may be in the area during pre-start
clearance, and (2) during airgun use, aid in establishing and
maintaining the EZ by alerting the visual observer and crew of marine
mammals that are outside of, but may approach and enter, the EZ.
L-DEO must use dedicated, trained, NMFS-approved PSOs. The PSOs
must have no tasks other than to conduct observational effort, record
observational data, and communicate with and instruct relevant vessel
crew with regard to the presence of marine mammals and mitigation
requirements. PSO resumes shall be provided to NMFS for approval.
At least one of the visual and two of the acoustic PSOs (discussed
below) aboard the vessel must have a minimum of 90 days at-sea
experience working in those roles, respectively, with no more than 18
months elapsed since the conclusion of the at-sea experience. One
visual PSO with such experience shall be designated as the lead for the
entire protected species observation team. The lead PSO shall serve as
primary point of contact for the vessel operator and ensure all PSO
requirements per the IHA are met. To the maximum extent practicable,
the experienced PSOs should be scheduled to be on duty with those PSOs
with appropriate training but who have not yet gained relevant
experience.
During survey operations (e.g., any day on which use of the
acoustic source is planned to occur, and whenever the
[[Page 30025]]
acoustic source is in the water, whether activated or not), a minimum
of two visual PSOs must be on duty and conducting visual observations
at all times during daylight hours (i.e., from 30 minutes prior to
sunrise through 30 minutes following sunset). Visual monitoring of the
pre-start clearance zone must begin no less than 30 minutes prior to
ramp-up, and monitoring must continue until one hour after use of the
acoustic source ceases or until 30 minutes past sunset. Visual PSOs
shall coordinate to ensure 360[deg] visual coverage around the vessel
from the most appropriate observation posts, and shall conduct visual
observations using binoculars and the naked eye while free from
distractions and in a consistent, systematic, and diligent manner.
PSOs shall establish and monitor the exclusion and buffer zones.
These zones shall be based upon the radial distance from the edges of
the acoustic source (rather than being based on the center of the array
or around the vessel itself). During use of the acoustic source (i.e.,
anytime airguns are active, including ramp-up), detections of marine
mammals within the buffer zone (but outside the EZ) shall be
communicated to the operator to prepare for the potential shutdown of
the acoustic source. Visual PSOs will immediately communicate all
observations to the on duty acoustic PSO(s), including any
determination by the PSO regarding species identification, distance,
and bearing and the degree of confidence in the determination. Any
observations of marine mammals by crew members shall be relayed to the
PSO team. During good conditions (e.g., daylight hours; Beaufort sea
state (BSS) 3 or less), visual PSOs shall conduct observations when the
acoustic source is not operating for comparison of sighting rates and
behavior with and without use of the acoustic source and between
acquisition periods, to the maximum extent practicable.
Visual PSOs may be on watch for a maximum of 4 consecutive hours
followed by a break of at least one hour between watches and may
conduct a maximum of 12 hours of observation per 24-hour period.
Combined observational duties (visual and acoustic but not at same
time) may not exceed 12 hours per 24-hour period for any individual
PSO.
Passive Acoustic Monitoring
Acoustic monitoring means the use of trained personnel (sometimes
referred to as passive acoustic monitoring (PAM) operators, herein
referred to as acoustic PSOs) to operate PAM equipment to acoustically
detect the presence of marine mammals. Acoustic monitoring involves
acoustically detecting marine mammals regardless of distance from the
source, as localization of animals may not always be possible. Acoustic
monitoring is intended to further support visual monitoring (during
daylight hours) in maintaining an EZ around the sound source that is
clear of marine mammals. In cases where visual monitoring is not
effective (e.g., due to weather, nighttime), acoustic monitoring may be
used to allow certain activities to occur, as further detailed below.
PAM would take place in addition to the visual monitoring program.
Visual monitoring typically is not effective during periods of poor
visibility or at night, and even with good visibility, is unable to
detect marine mammals when they are below the surface or beyond visual
range. Acoustic monitoring can be used in addition to visual
observations to improve detection, identification, and localization of
cetaceans. The acoustic monitoring would serve to alert visual PSOs (if
on duty) when vocalizing cetaceans are detected. It is only useful when
marine mammals vocalize, but it can be effective either by day or by
night, and does not depend on good visibility. It would be monitored in
real time so that the visual observers can be advised when cetaceans
are detected.
The R/V Langseth will use a towed PAM system, which must be
monitored by at a minimum one on duty acoustic PSO beginning at least
30 minutes prior to ramp-up and at all times during use of the acoustic
source. Acoustic PSOs may be on watch for a maximum of 4 consecutive
hours followed by a break of at least one hour between watches and may
conduct a maximum of 12 hours of observation per 24-hour period.
Combined observational duties (acoustic and visual but not at same
time) may not exceed 12 hours per 24-hour period for any individual
PSO.
Survey activity may continue for 30 minutes when the PAM system
malfunctions or is damaged, while the PAM operator diagnoses the issue.
If the diagnosis indicates that the PAM system must be repaired to
solve the problem, operations may continue for an additional 5 hours
without acoustic monitoring during daylight hours only under the
following conditions:
<bullet> Sea state is less than or equal to BSS 4;
<bullet> No marine mammals (excluding delphinids) detected solely
by PAM in the applicable EZ in the previous 2 hours;
<bullet> NMFS is notified via email as soon as practicable with the
time and location in which operations began occurring without an active
PAM system; and
<bullet> Operations with an active acoustic source, but without an
operating PAM system, do not exceed a cumulative total of 5 hours in
any 24-hour period.
Establishment of Exclusion and Pre-Start Clearance Zones
An EZ is a defined area within which occurrence of a marine mammal
triggers mitigation action intended to reduce the potential for certain
outcomes, e.g., auditory injury, disruption of critical behaviors. The
PSOs would establish a minimum EZ with a 500-m radius. The 500-m EZ
would be based on radial distance from the edge of the airgun array
(rather than being based on the center of the array or around the
vessel itself). With certain exceptions (described below), if a marine
mammal appears within or enters this zone, the acoustic source would be
shut down.
The pre-start clearance zone is defined as the area that must be
clear of marine mammals prior to beginning ramp-up of the acoustic
source, and includes the EZ plus the buffer zone. Detections of marine
mammals within the pre-start clearance zone would prevent airgun
operations from beginning (i.e., ramp-up).
The 500-m EZ is intended to be precautionary in the sense that it
would be expected to contain sound exceeding the injury criteria for
all cetacean hearing groups, (based on the dual criteria of
SEL<INF>cum</INF> and peak SPL), while also providing a consistent,
reasonably observable zone within which PSOs would typically be able to
conduct effective observational effort. Additionally, a 500-m EZ is
expected to minimize the likelihood that marine mammals will be exposed
to levels likely to result in more severe behavioral responses.
Although significantly greater distances may be observed from an
elevated platform under good conditions, we believe that 500 m is
likely regularly attainable for PSOs using the naked eye during typical
conditions. The pre-start clearance zone simply represents the addition
of a buffer to the EZ, doubling the EZ size during pre-clearance.
An extended EZ of 1,500 m must be enforced for all beaked whales.
No buffer of this extended EZ is required.
Pre-Start Clearance and Ramp-Up
Ramp-up (sometimes referred to as ``soft start'') means the gradual
and systematic increase of emitted sound levels from an airgun array.
Ramp-up begins by first activating a single airgun of the smallest
volume, followed by doubling the number of active elements
[[Page 30026]]
in stages until the full complement of an array's airguns are active.
Each stage should be approximately the same duration, and the total
duration should not be less than approximately 20 minutes. The intent
of pre-start clearance observation (30 minutes) is to ensure no
protected species are observed within the pre-clearance zone (or
extended EZ, for beaked whales) prior to the beginning of ramp-up.
During pre-start clearance period is the only time observations of
marine mammals in the buffer zone would prevent operations (i.e., the
beginning of ramp-up). The intent of ramp-up is to warn marine mammals
of pending seismic operations and to allow sufficient time for those
animals to leave the immediate vicinity. A ramp-up procedure, involving
a step-wise increase in the number of airguns firing and total array
volume until all operational airguns are activated and the full volume
is achieved, is required at all times as part of the activation of the
acoustic source. All operators must adhere to the following pre-start
clearance and ramp-up requirements:
<bullet> The operator must notify a designated PSO of the planned
start of ramp-up as agreed upon with the lead PSO; the notification
time should not be less than 60 minutes prior to the planned ramp-up in
order to allow the PSOs time to monitor the pre-start clearance zone
(and extended EZ) for 30 minutes prior to the initiation of ramp-up
(pre-start clearance);
<bullet> Ramp-ups shall be scheduled so as to minimize the time
spent with the source activated prior to reaching the designated run-
in;
<bullet> One of the PSOs conducting pre-start clearance
observations must be notified again immediately prior to initiating
ramp-up procedures and the operator must receive confirmation from the
PSO to proceed;
<bullet> Ramp-up may not be initiated if any marine mammal is
within the applicable exclusion or buffer zone. If a marine mammal is
observed within the pre-start clearance zone (or extended EZ, for
beaked whales) during the 30 minute pre-start clearance period, ramp-up
may not begin until the animal(s) has been observed exiting the zones
or until an additional time period has elapsed with no further
sightings (15 minutes for small odontocetes and pinnipeds, and 30
minutes for all mysticetes and all other odontocetes, including sperm
whales, beaked whales, and large delphinids, such as killer whales);
<bullet> Ramp-up shall begin by activating a single airgun of the
smallest volume in the array and shall continue in stages by doubling
the number of active elements at the commencement of each stage, with
each stage of approximately the same duration. Duration shall not be
less than 20 minutes. The operator must provide information to the PSO
documenting that appropriate procedures were followed;
<bullet> PSOs must monitor the pre-start clearance zone (and
extended EZ) during ramp-up, and ramp-up must cease and the source must
be shut down upon detection of a marine mammal within the applicable
zone. Once ramp-up has begun, detections of marine mammals within the
buffer zone do not require shutdown, but such observation shall be
communicated to the operator to prepare for the potential shutdown;
<bullet> Ramp-up may occur at times of poor visibility, including
nighttime, if appropriate acoustic monitoring has occurred with no
detections in the 30 minutes prior to beginning ramp-up. Acoustic
source activation may only occur at times of poor visibility where
operational planning cannot reasonably avoid such circumstances;
<bullet> If the acoustic source is shut down for brief periods
(i.e., less than 30 minutes) for reasons other than that described for
shutdown (e.g., mechanical difficulty), it may be activated again
without ramp-up if PSOs have maintained constant visual and/or acoustic
observation and no visual or acoustic detections of marine mammals have
occurred within the applicable EZ. For any longer shutdown, pre-start
clearance observation and ramp-up are required. For any shutdown at
night or in periods of poor visibility (e.g., BSS 4 or greater), ramp-
up is required, but if the shutdown period was brief and constant
observation was maintained, pre-start clearance watch of 30 minutes is
not required; and
<bullet> Testing of the acoustic source involving all elements
requires ramp-up. Testing limited to individual source elements or
strings does not require ramp-up but does require pre-start clearance
of 30 min.
Shutdown
The shutdown of an airgun array requires the immediate de-
activation of all individual airgun elements of the array. Any PSO on
duty will have the authority to delay the start of survey operations or
to call for shutdown of the acoustic source if a marine mammal is
detected within the applicable EZ. The operator must also establish and
maintain clear lines of communication directly between PSOs on duty and
crew controlling the acoustic source to ensure that shutdown commands
are conveyed swiftly while allowing PSOs to maintain watch. When both
visual and acoustic PSOs are on duty, all detections will be
immediately communicated to the remainder of the on-duty PSO team for
potential verification of visual observations by the acoustic PSO or of
acoustic detections by visual PSOs. When the airgun array is active
(i.e., anytime one or more airguns is active, including during ramp-up)
and (1) a marine mammal appears within or enters the applicable EZ and/
or (2) a marine mammal (other than delphinids, see below) is detected
acoustically and localized within the applicable EZ, the acoustic
source will be shut down. When shutdown is called for by a PSO, the
acoustic source will be immediately deactivated and any dispute
resolved only following deactivation. Additionally, shutdown will occur
whenever PAM alone (without visual sighting), confirms presence of
marine mammal(s) in the EZ. If the acoustic PSO cannot confirm presence
within the EZ, visual PSOs will be notified but shutdown is not
required.
Following a shutdown, airgun activity would not resume until the
marine mammal has cleared the EZ. The animal would be considered to
have cleared the EZ if it is visually observed to have departed the EZ
(i.e., animal is not required to fully exit the buffer zone where
applicable), or it has not been seen within the EZ for 15 minutes for
small odontocetes and pinnipeds, or 30 minutes for all mysticetes and
all other odontocetes, including sperm whales, beaked whales, and large
delphinids, such as killer whales.
The shutdown requirement can be waived for small dolphins if an
individual is detected within the EZ. As defined here, the small
dolphin group is intended to encompass those members of the Family
Delphinidae most likely to voluntarily approach the source vessel for
purposes of interacting with the vessel and/or airgun array (e.g., bow
riding). This exception to the shutdown requirement applies solely to
specific genera of small dolphins (Lagenorhynchus and Lissodelphis).
We include this small dolphin exception because shutdown
requirements for small dolphins under all circumstances represent
practicability concerns without likely commensurate benefits for the
animals in question. Small dolphins are generally the most commonly
observed marine mammals in the specific geographic region and would
typically be the only marine mammals likely to intentionally approach
the vessel. As described above, auditory injury is extremely unlikely
to occur for mid-frequency cetaceans (e.g., delphinids),
[[Page 30027]]
as this group is relatively insensitive to sound produced at the
predominant frequencies in an airgun pulse while also having a
relatively high threshold for the onset of auditory injury (i.e.,
permanent threshold shift).
A large body of anecdotal evidence indicates that small dolphins
commonly approach vessels and/or towed arrays during active sound
production for purposes of bow riding, with no apparent effect observed
in those delphinoids (e.g., Barkaszi et al., 2012, 2018). The potential
for increased shutdowns resulting from such a measure would require the
Langseth to revisit the missed track line to reacquire data, resulting
in an overall increase in the total sound energy input to the marine
environment and an increase in the total duration over which the survey
is active in a given area. Although other mid-frequency hearing
specialists (e.g., large delphinids) are no more likely to incur
auditory injury than are small dolphins, they are much less likely to
approach vessels. Therefore, retaining a shutdown requirement for large
delphinids would not have similar impacts in terms of either
practicability for the applicant or corollary increase in sound energy
output and time on the water. We do anticipate some benefit for a
shutdown requirement for large delphinids in that it simplifies
somewhat the total range of decision-making for PSOs and may preclude
any potential for physiological effects other than to the auditory
system as well as some more severe behavioral reactions for any such
animals in close proximity to the source vessel.
Visual PSOs shall use best professional judgment in making the
decision to call for a shutdown if there is uncertainty regarding
identification (i.e., whether the observed marine mammal(s) belongs to
one of the delphinid genera for which shutdown is waived or one of the
species with a larger EZ).
L-DEO must implement shutdown if a marine mammal species for which
take was not authorized, or a species for which authorization was
granted but the takes have been met, approaches the Level A or Level B
harassment zones. L-DEO must also implement shutdown if any of the
following are observed at any distance:
<bullet> Any large whale (defined as a sperm whale or any mysticete
species) with a calf (defined as an animal less than two-thirds the
body size of an adult observed to be in close association with an
adult);
<bullet> An aggregation of six or more large whales; and/or
<bullet> A North Pacific right whale.
Vessel Strike Avoidance
1. Vessel operators and crews must maintain a vigilant watch for
all protected species and slow down, stop their vessel, or alter
course, as appropriate and regardless of vessel size, to avoid striking
any marine mammal. A visual observer aboard the vessel must monitor a
vessel strike avoidance zone around the vessel (distances stated
below). Visual observers monitoring the vessel strike avoidance zone
may be third-party observers (i.e., PSOs) or crew members, but crew
members responsible for these duties must be provided sufficient
training to 1) distinguish marine mammals from other phenomena and 2)
broadly to identify a marine mammal as a right whale, other whale
(defined in this context as sperm whales or baleen whales other than
right whales), or other marine mammal.
2. Vessel speeds must also be reduced to 10 kn or less when mother/
calf pairs, pods, or large assemblages of cetaceans are observed near a
vessel.
3. All vessels must maintain a minimum separation distance of 500 m
from right whales. If a whale is observed but cannot be confirmed as a
species other than a right whale, the vessel operator must assume that
it is a right whale and take appropriate action.
4. All vessels must maintain a minimum separation distance of 100 m
from sperm whales and all other baleen whales.
5. All vessels must, to the maximum extent practicable, attempt to
maintain a minimum separation distance of 50 m from all other marine
mammals, with an understanding that at times this may not be possible
(e.g., for animals that approach the vessel).
6. When marine mammals are sighted while a vessel is underway, the
vessel shall take action as necessary to avoid violating the relevant
separation distance (e.g., attempt to remain parallel to the animal's
course, avoid excessive speed or abrupt changes in direction until the
animal has left the area). If marine mammals are sighted within the
relevant separation distance, the vessel must reduce speed and shift
the engine to neutral, not engaging the engines until animals are clear
of the area. This does not apply to any vessel towing gear or any
vessel that is navigationally constrained.
7. These requirements do not apply in any case where compliance
would create an imminent and serious threat to a person or vessel or to
the extent that a vessel is restricted in its ability to maneuver and,
because of the restriction, cannot comply.
We have carefully evaluated the suite of mitigation measures
described here and considered a range of other measures in the context
of ensuring that we prescribe the means of effecting the least
practicable adverse impact on the affected marine mammal species and
stocks and their habitat. Based on our evaluation of the proposed
measures, as well as other measures considered by NMFS described above,
NMFS has preliminarily determined that the 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.
Mitigation Measures in Canadian Waters
As stated previously, NMFS cannot authorize the incidental take of
marine mammals in the territorial seas of foreign nations, as the MMPA
does not apply in those waters. L-DEO is required to adhere to the
mitigation measures described above while operating within the U.S. EEZ
and Canadian EEZ. The requirements do not apply within Canadian
territorial waters. NMFS expects that DFO may prescribe mitigation
measures that would apply to L-DEO's survey operations within the
Canadian EEZ and Canadian territorial waters but is currently unaware
of the specifics of any potential measures. While operating within the
Canadian EEZ but outside Canadian territorial waters, if mitigation
requirements prescribed by NMFS differ from the requirements
established under Canadian law, L-DEO would adhere to the most
protective measure. For operations in Canadian territorial waters, L-
DEO would implement measures required under Canadian law (if any). If
information regarding measures required under Canadian law becomes
available prior to NMFS' final decision on this request for IHA, NMFS
will consider it as appropriate in making its negligible impact
determination.
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
[[Page 30028]]
mammals that are expected to be present in the proposed action area.
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 action; 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.
Vessel-Based Visual Monitoring
As described above, PSO observations would take place during
daytime airgun operations. During seismic operations, at least five
visual PSOs would be based aboard the Langseth. Two visual PSOs would
be on duty at all time during daytime hours. Monitoring shall be
conducted in accordance with the following requirements:
<bullet> The operator shall provide PSOs with bigeye binoculars
(e.g., 25 x 150; 2.7 view angle; individual ocular focus; height
control) of appropriate quality (i.e., Fujinon or equivalent) solely
for PSO use. These shall be pedestal-mounted on the deck at the most
appropriate vantage point that provides for optimal sea surface
observation, PSO safety, and safe operation of the vessel; and
<bullet> The operator will work with the selected third-party
observer provider to ensure PSOs have all equipment (including backup
equipment) needed to adequately perform necessary tasks, including
accurate determination of distance and bearing to observed marine
mammals.
PSOs must have the following requirements and qualifications:
<bullet> PSOs shall be independent, dedicated, trained visual and
acoustic PSOs and must be employed by a third-party observer provider;
<bullet> PSOs shall have no tasks other than to conduct
observational effort (visual or acoustic), collect data, and
communicate with and instruct relevant vessel crew with regard to the
presence of protected species and mitigation requirements (including
brief alerts regarding maritime hazards);
<bullet> PSOs shall have successfully completed an approved PSO
training course appropriate for their designated task (visual or
acoustic). Acoustic PSOs are required to complete specialized training
for operating PAM systems and are encouraged to have familiarity with
the vessel with which they will be working;
<bullet> PSOs can act as acoustic or visual observers (but not at
the same time) as long as they demonstrate that their training and
experience are sufficient to perform the task at hand;
<bullet> NMFS must review and approve PSO resumes accompanied by a
relevant training course information packet that includes the name and
qualifications (i.e., experience, training completed, or educational
background) of the instructor(s), the course outline or syllabus, and
course reference material as well as a document stating successful
completion of the course;
<bullet> NMFS shall have one week to approve PSOs from the time
that the necessary information is submitted, after which PSOs meeting
the minimum requirements shall automatically be considered approved;
<bullet> PSOs must successfully complete relevant training,
including completion of all required coursework and passing (80 percent
or greater) a written and/or oral examination developed for the
training program;
<bullet> PSOs must have successfully attained a bachelor's degree
from an accredited college or university with a major in one of the
natural sciences, a minimum of 30 semester hours or equivalent in the
biological sciences, and at least one undergraduate course in math or
statistics; and
<bullet> The educational requirements may be waived if the PSO has
acquired the relevant skills through alternate experience. Requests for
such a waiver shall be submitted to NMFS and must include written
justification. Requests shall be granted or denied (with justification)
by NMFS within one week of receipt of submitted information. Alternate
experience that may be considered includes, but is not limited to (1)
secondary education and/or experience comparable to PSO duties; (2)
previous work experience conducting academic, commercial, or
government-sponsored protected species surveys; or (3) previous work
experience as a PSO; the PSO should demonstrate good standing and
consistently good performance of PSO duties.
For data collection purposes, PSOs shall use standardized data
collection forms, whether hard copy or electronic. PSOs shall record
detailed information about any implementation of mitigation
requirements, including the distance of animals to the acoustic source
and description of specific actions that ensued, the behavior of the
animal(s), any observed changes in behavior before and after
implementation of mitigation, and if shutdown was implemented, the
length of time before any subsequent ramp-up of the acoustic source. If
required mitigation was not implemented, PSOs should record a
description of the circumstances. At a minimum, the following
information must be recorded:
<bullet> Vessel names (source vessel and other vessels associated
with survey) and call signs;
<bullet> PSO names and affiliations;
<bullet> Dates of departures and returns to port with port name;
<bullet> Date and participants of PSO briefings;
<bullet> Dates and times (Greenwich Mean Time) of survey effort and
times corresponding with PSO effort;
<bullet> Vessel location (latitude/longitude) when survey effort
began and ended and vessel location at beginning and end of visual PSO
duty shifts;
<bullet> Vessel heading and speed at beginning and end of visual
PSO duty shifts and upon any line change;
<bullet> Environmental conditions while on visual survey (at
beginning and end of PSO shift and whenever conditions changed
significantly), including BSS and any other relevant weather conditions
including cloud cover, fog, sun glare, and overall visibility to the
horizon;
<bullet> Factors that may have contributed to impaired observations
during each PSO shift change or as needed as environmental conditions
changed (e.g., vessel traffic, equipment malfunctions); and
[[Page 30029]]
<bullet> Survey activity information, such as acoustic source power
output while in operation, number and volume of airguns operating in
the array, tow depth of the array, and any other notes of significance
(i.e., pre-start clearance, ramp-up, shutdown, testing, shooting, ramp-
up completion, end of operations, streamers, etc.).
The following information should be recorded upon visual
observation of any protected species:
<bullet> Watch status (sighting made by PSO on/off effort,
opportunistic, crew, alternate vessel/platform);
<bullet> PSO who sighted the animal;
<bullet> Time of sighting;
<bullet> Vessel location at time of sighting;
<bullet> Water depth;
<bullet> Direction of vessel's travel (compass direction);
<bullet> Direction of animal's travel relative to the vessel;
<bullet> Pace of the animal;
<bullet> Estimated distance to the animal and its heading relative
to vessel at initial sighting;
<bullet> Identification of the animal (e.g., genus/species, lowest
possible taxonomic level, or unidentified) and the composition of the
group if there is a mix of species;
<bullet> Estimated number of animals (high/low/best);
<bullet> Estimated number of animals by cohort (adults, yearlings,
juveniles, calves, group composition, etc.);
<bullet> Description (as many distinguishing features as possible
of each individual seen, including length, shape, color, pattern, scars
or markings, shape and size of dorsal fin, shape of head, and blow
characteristics);
<bullet> Detailed behavior observations (e.g., number of blows/
breaths, number of surfaces, breaching, spyhopping, diving, feeding,
traveling; as explicit and detailed as possible; note any observed
changes in behavior);
<bullet> Animal's closest point of approach (CPA) and/or closest
distance from any element of the acoustic source;
<bullet> Platform activity at time of sighting (e.g., deploying,
recovering, testing, shooting, data acquisition, other); and
<bullet> Description of any actions implemented in response to the
sighting (e.g., delays, shutdown, ramp-up) and time and location of the
action.
If a marine mammal is detected while using the PAM system, the
following information should be recorded:
<bullet> An acoustic encounter identification number, and whether
the detection was linked with a visual sighting;
<bullet> Date and time when first and last heard;
<bullet> Types and nature of sounds heard (e.g., clicks, whistles,
creaks, burst pulses, continuous, sporadic, strength of signal); and
<bullet> Any additional information recorded such as water depth of
the hydrophone array, bearing of the animal to the vessel (if
determinable), species or taxonomic group (if determinable),
spectrogram screenshot, and any other notable information.
Reporting
A report would be submitted to NMFS within 90 days after the end of
the cruise. The report would summarize the dates and locations of
seismic operations, and all marine mammal sightings (dates, times,
locations, activities, associated seismic survey activities), and
provide full documentation of methods, results, and interpretation
pertaining to all monitoring.
The draft report shall also include geo-referenced time-stamped
vessel tracklines for all time periods during which airguns were
operating. Tracklines should include points recording any change in
airgun status (e.g., when the airguns began operating, when they were
turned off, or when they changed from full array to single gun or vice
versa). GIS files shall be provided in ESRI shapefile format and
include the UTC date and time, latitude in decimal degrees, and
longitude in decimal degrees. All coordinates shall be referenced to
the WGS84 geographic coordinate system. In addition to the report, all
raw observational data shall be made available to NMFS. The report must
summarize the data collected as described above and in the IHA. A final
report must be submitted within 30 days following resolution of any
comments on the draft report.
Reporting Injured or Dead Marine Mammals
Discovery of injured or dead marine mammals--In the event that
personnel involved in survey activities covered by the authorization
discover an injured or dead marine mammal, the L-DEO shall report the
incident to the Office of Protected Resources (OPR), NMFS and to the
NMFS Alaska Regional Stranding Coordinator as soon as feasible. The
report must include the following information:
<bullet> Time, date, and location (latitude/longitude) of the first
discovery (and updated location information if known and applicable);
<bullet> Species identification (if known) or description of the
animal(s) involved;
<bullet> Condition of the animal(s) (including carcass condition if
the animal is dead);
<bullet> Observed behaviors of the animal(s), if alive;
<bullet> If available, photographs or video footage of the
animal(s); and
<bullet> General circumstances under which the animal was
discovered.
Vessel strike--In the event of a ship strike of a marine mammal by
any vessel involved in the activities covered by the authorization, L-
DEO shall report the incident to OPR, NMFS and to the NMFS Alaska
Regional Stranding Coordinator as soon as feasible. The report must
include the following information:
<bullet> Time, date, and location (latitude/longitude) of the
incident;
<bullet> Vessel's speed during and leading up to the incident;
<bullet> Vessel's course/heading and what operations were being
conducted (if applicable);
<bullet> Status of all sound sources in use;
<bullet> Description of avoidance measures/requirements that were
in place at the time of the strike and what additional measure were
taken, if any, to avoid strike;
<bullet> Environmental conditions (e.g., wind speed and direction,
Beaufort sea state, cloud cover, visibility) immediately preceding the
strike;
<bullet> Species identification (if known) or description of the
animal(s) involved;
<bullet> Estimated size and length of the animal that was struck;
<bullet> Description of the behavior of the animal immediately
preceding and following the strike;
<bullet> If available, description of the presence and behavior of
any other marine mammals present immediately preceding the strike;
<bullet> Estimated fate of the animal (e.g., dead, injured but
alive, injured and moving, blood or tissue observed in the water,
status unknown, disappeared); and
<bullet> To the extent practicable, photographs or video footage of
the animal(s).
Actions To Minimize Additional Harm To Live-Stranded (or Milling)
Marine Mammals
In the event of a live stranding (or near-shore atypical milling)
event within 50 km of the survey operations, where the NMFS stranding
network is engaged in herding or other interventions to return animals
to the water, the Director of OPR, NMFS (or designee) will advise L-DEO
of the need to implement shutdown for all active acoustic sources
operating within 50 km of the stranding. Procedures related to
shutdowns for live stranding or milling marine mammals include the
following:
<bullet> If at any time, the marine mammal(s) die or are
euthanized, or if
[[Page 30030]]
herding/intervention efforts are stopped, the Director of OPR, NMFS (or
designee) will advise L-DEO that the shutdown around the animals'
location is no longer needed.
<bullet> Otherwise, shutdown procedures will remain in effect until
the Director of OPR, NMFS (or designee) determines and advises L-DEO
that all live animals involved have left the area (either of their own
volition or following an intervention).
<bullet> If further observations of the marine mammals indicate the
potential for re-stranding, additional coordination with L-DEO will be
required to determine what measures are necessary to minimize that
likelihood (e.g., extending the shutdown or moving operations farther
away) and to implement those measures as appropriate.
Additional Information Requests--If NMFS determines that the
circumstances of any marine mammal stranding found in the vicinity of
the activity suggest investigation of the association with survey
activities is warranted, and an investigation into the stranding is
being pursued, NMFS will submit a written request to L-DEO indicating
that the following initial available information must be provided as
soon as possible, but no later than 7 business days after the request
for information:
<bullet> Status of all sound source use in the 48 hours preceding
the estimated time of stranding and within 50 km of the discovery/
notification of the stranding by NMFS; and
<bullet> If available, description of the behavior of any marine
mammal(s) observed preceding (i.e., within 48 hours and 50 km) and
immediately after the discovery of the stranding.
In the event that the investigation is still inconclusive, the
investigation of the association of the survey activities is still
warranted, and the investigation is still being pursued, NMFS may
provide additional information requests, in writing, regarding the
nature and location of survey operations prior to the time period
above.
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 responses (e.g., intensity, duration), the context
of any responses (e.g., critical reproductive time or location,
migration), 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's 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 environmental 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, our analysis applies to all species listed in
Table 1, given that NMFS expects the anticipated effects of the planned
geophysical survey to be 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, NMFS has identified species-specific factors to inform the
analysis.
As described above, we propose to authorize only the takes
estimated to occur outside of Canadian territorial waters (Table 7);
however, for the purposes of our negligible impact analysis and
determination, we consider the total number of takes that are
anticipated to occur as a result of the entire survey (including the
portion of the survey that would occur within the Canadian territorial
waters (approximately 13 percent of the survey) (Table 8).
Table 8--Total Estimated Take Including Canadian Territorial Waters
----------------------------------------------------------------------------------------------------------------
Level B Level A
harassment harassment Level B Level A
(excluding (excluding harassment harassment Total Total
Species Canadian Canadian (Canadian (Canadian Level B Level A
territorial territorial territorial territorial harassment harassment
waters) waters) waters) waters)
----------------------------------------------------------------------------------------------------------------
Gray whale, WNP................... 2 0 1 0 3 0
Gray whale, ENP................... 1,448 45 666 16 2,114 61
Humpback whale.................... 403 14 165 4 568 18
Blue whale........................ 31 1 4 0 35 1
Fin whale......................... 873 44 69 1 942 45
Sei whale......................... 34 1 7 0 41 1
Minke whale....................... 57 2 14 0 71 2
Sperm whale....................... 131 0 22 0 153 0
Baird's beaked whale.............. 29 0 2 0 31 0
Stejneger's beaked whale.......... 120 0 9 0 129 0
Cuvier's beaked whale............. 114 0 9 0 123 0
Pacific white-sided dolphin....... 1,374 0 191 0 1,565 0
Northern right whale dolphin...... 927 0 451 0 1,378 0
Risso's dolphin................... 22 0 22 0 44 0
Killer whale...................... 290 0 89 0 379 0
Dall's porpoise................... 5,661 178 1,825 36 7,486 214
Harbor porpoise................... 990 26 455 9 1,445 35
Northern fur seal................. 5,812 0 1,213 0 7,025 0
California sea lion............... 1,258 0 433 0 1,691 0
Steller sea lion, wDPS............ 54 0 55 0 109 0
Steller sea lion, eDPS............ 2,381 0 2,467 0 4,848 0
Northern elephant seal............ 6,850 0 1,429 0 8,279 0
Harbor seal....................... 6,012 0 6,228 0 12,240 0
----------------------------------------------------------------------------------------------------------------
[[Page 30031]]
NMFS does not anticipate that serious injury or mortality would
occur as a result of L-DEO's planned survey, even in the absence of
mitigation, and none would be authorized. Similarly, non-auditory
physical effects, stranding, and vessel strike are not expected to
occur.
We are proposing to authorize a limited number of instances of
Level A harassment of seven species (low- and high-frequency cetacean
hearing groups only) and Level B harassment only of the remaining
marine mammal species. However, we believe that any PTS incurred in
marine mammals as a result of the planned activity would be in the form
of only a small degree of PTS, not total deafness, because of the
constant movement of both the R/V Langseth and of the marine mammals in
the project areas, as well as the fact that the vessel is not expected
to remain in any one area in which individual marine mammals would be
expected to concentrate for an extended period of time. Since the
duration of exposure to loud sounds will be relatively short it would
be unlikely to affect the fitness of any individuals. Also, as
described above, we expect that marine mammals would likely move away
from a sound source that represents an aversive stimulus, especially at
levels that would be expected to result in PTS, given sufficient notice
of the R/V Langseth's approach due to the vessel's relatively low speed
when conducting seismic surveys. We expect that the majority of takes
would be in the form of short-term Level B behavioral harassment in the
form of temporary avoidance of the area or decreased foraging (if such
activity were occurring), reactions that are considered to be of low
severity and with no lasting biological consequences (e.g., Southall et
al., 2007, Ellison et al., 2012).
Marine mammal habitat may be impacted by elevated sound levels, but
these impacts would be temporary. Prey species are mobile and are
broadly distributed throughout the project areas; therefore, marine
mammals that may be temporarily displaced during survey activities are
expected to be able to resume foraging once they have moved away from
areas with disturbing levels of underwater noise. Because of the
relatively short duration (27 days) and temporary nature of the
disturbance, the availability of similar habitat and resources in the
surrounding area, the impacts to marine mammals and the food sources
that they utilize are not expected to cause significant or long-term
consequences for individual marine mammals or their populations.
The tracklines of this survey either traverse or are proximal to
critical habitat for the Mexico DPS of humpback whales and for Steller
sea lions, and to feeding BIAs for humpback whales in general
(including both the Hawaii and Mexico DPSs/Central North Pacific stock
whales that are anticipated to occur in the survey area). As described
previously, the survey area is near a feeding BIA for gray whales and
covers the gray whale migratory BIA. However, these BIAs would not be
affected as they are spatially and temporally separated, respectively,
from the survey.
Yazvenko et al. (2007) reported no apparent changes in the
frequency of feeding activity in Western gray whales exposed to airgun
sounds in their feeding grounds near Sakhalin Island. Goldbogen et al.
(2013) found blue whales feeding on highly concentrated prey in shallow
depths (such as the conditions expected within humpback feeding BIAs)
were less likely to respond and cease foraging than whales feeding on
deep, dispersed prey when exposed to simulated sonar sources,
suggesting that the benefits of feeding for humpbacks foraging on high-
density prey may outweigh perceived harm from the acoustic stimulus,
such as the seismic survey (Southall et al., 2016). Additionally, L-DEO
will shut down the airgun array upon observation of an aggregation of
six or more large whales, which would reduce impacts to cooperatively
foraging animals. For all habitats, no physical impacts to habitat are
anticipated from seismic activities. While SPLs of sufficient strength
have been known to cause injury to fish and fish and invertebrate
mortality, in feeding habitats, the most likely impact to prey species
from survey activities would be temporary avoidance of the affected
area and any injury or mortality of prey species would be localized
around the survey and not of a degree that would adversely impact
marine mammal foraging. The duration of fish avoidance of a given area
after survey effort stops is unknown, but a rapid return to normal
recruitment, distribution and behavior is expected. Given the short
operational seismic time near or traversing important habitat areas, as
well as the ability of cetaceans and prey species to move away from
acoustic sources, NMFS expects that there would be, at worst, minimal
impacts to animals and habitat within these areas.
Critical habitat for Steller sea lions has been established at
three rookeries in southeast Alaska (Hazy Island, White Sisters Island,
and Forrester Island near Dixon Entrance), at several major haul-outs,
and including aquatic zones that extend 0.9 km seaward and air zones
extending 0.9 km above the rookeries. Steller sea lions occupy
rookeries and pup from late-May through early-July (NMFS. 2008),
indicating that L-DEO's survey is unlikely to impact important sea lion
behaviors in critical habitat. Impacts to Steller sea lions within
these areas, and throughout the survey area, as well as impacts to
other pinniped species, are expected to be limited to short-term
behavioral disturbance, with no lasting biological consequences.
Negligible Impact Conclusions
The proposed survey would be of short duration (27 days of seismic
operations), and the acoustic ``footprint'' of the proposed survey
would be small relative to the ranges of the marine mammals that would
potentially be affected. Sound levels would increase in the marine
environment in a relatively small area surrounding the vessel compared
to the range of the marine mammals within the proposed survey area.
Short term exposures to survey operations are not likely to
significantly disrupt marine mammal behavior, and the potential for
longer-term avoidance of important areas is limited.
The proposed mitigation measures are expected to reduce the number
and/or severity of takes by allowing for detection of marine mammals in
the vicinity of the vessel by visual and acoustic observers, and by
minimizing the severity of any potential exposures via shutdowns of the
airgun array. Based on previous monitoring reports for substantially
similar activities that have been previously authorized by NMFS, we
expect that the proposed mitigation will be effective in preventing, at
least to some extent, potential PTS in marine mammals that may
otherwise occur in the absence of the proposed mitigation (although all
authorized PTS has been accounted for in this analysis).
NMFS concludes that exposures to marine mammal species and stocks
due to L-DEO's proposed survey would result in only short-term
(temporary and short in duration) effects to individuals exposed, over
relatively small areas of the affected animals' ranges. Animals may
temporarily avoid the immediate area, but are not expected to
permanently abandon the area. Major shifts in habitat use,
distribution, or foraging success are not expected. NMFS does not
anticipate the proposed take estimates to impact annual rates of
recruitment or survival.
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 the
[[Page 30032]]
species or stock through effects on annual rates of recruitment or
survival:
<bullet> No serious injury or mortality is anticipated or proposed
to be authorized;
<bullet> The proposed activity is temporary and of relatively short
duration (27 days);
<bullet> The anticipated impacts of the proposed activity on marine
mammals would primarily be temporary behavioral changes due to
avoidance of the area around the survey vessel;
<bullet> The number of instances of potential PTS that may occur
are expected to be very small in number. Instances of potential PTS
that are incurred in marine mammals are expected to be of a low level,
due to constant movement of the vessel and of the marine mammals in the
area, and the nature of the survey design (not concentrated in areas of
high marine mammal concentration);
<bullet> The availability of alternate areas of similar habitat
value for marine mammals to temporarily vacate the survey area during
the proposed survey to avoid exposure to sounds from the activity;
<bullet> The potential adverse effects on fish or invertebrate
species that serve as prey species for marine mammals from the proposed
survey would be temporary and spatially limited, and impacts to marine
mammal foraging would be minimal; and
<bullet> The proposed mitigation measures, including visual and
acoustic monitoring and shutdowns are expected to minimize potential
impacts to marine mammals (both amount and severity).
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 mitigation and
monitoring 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 above, only small numbers of incidental take 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.
There are several stocks for which the estimated instances of take
appear high when compared to the stock abundance (Table 7), or for
which there is no currently accepted stock abundance estimate. These
include the fin whale, minke whale, sperm whale, three species of
beaked whale, four stocks of killer whales, harbor porpoise, and one
stock of harbor seal. However, when other qualitative factors are used
to inform an assessment of the likely number of individual marine
mammals taken, the resulting numbers are appropriately considered
small. We discuss these in further detail below.
For all other stocks (aside from those referenced above and
discussed below), the proposed take is less than one-third of the best
available stock abundance (recognizing that some of those takes may be
repeats of the same individual, thus rendering the actual percentage
even lower), and noting that we generally excluded consideration of
abundance information for British Columbia in considering the amount of
take relative to the best available stock abundance information.
The stock abundance estimates for the fin, minke, beaked, and sperm
whale stocks that occur in the survey area are unknown, according to
the latest SARs. The same is true for the harbor porpoise. Therefore,
we reviewed other scientific information in making our small numbers
determinations for these species. As noted previously, partial
abundance estimates of 1,233 and 2,020 minke whales are available for
shelf and nearshore waters between the Kenai Peninsula and Amchitka
Pass and for the eastern Bering Sea shelf, respectively. For the minke
whale, these partial abundance estimates alone are sufficient to
demonstrate that the proposed take number of 59 is of small numbers.
The same surveys produced partial abundance estimates of 1,652 and
1,061 fin whales, for the same areas, respectively. Considering these
two partial abundance estimates in conjunction with the British
Columbia abundance estimate of 329 whales produces a total partial
estimate of 3,042 whales for shelf and nearshore waters between the
Kenai Peninsula and Amchitka Pass, the eastern Bering Sea shelf, and
British Columbia. Given that the Northeast Pacific stock of fin whale's
range is described as covering the entire GOA and Bering Sea, we
reasonably assume that a total abundance estimate for the stock would
show that the take number proposed for authorization (917) is small. In
addition, for these stocks as well as for other stocks discussed below
whose range spans the GOA, given that the estimated take will take
place in a relatively small portion of the stock's range, it is likely
there would be repeat takes of a smaller number of individuals, and
therefore, the number of individual animals taken will be lower.
As noted previously, Kato and Miyashita (1998) produced an
abundance estimate of 102,112 sperm whales in the western North
Pacific. However, this estimate is believed to be positively biased. We
therefore refer to Barlow and Taylor (2005)'s estimate of 26,300 sperm
whales in the northeast temperate Pacific to demonstrate that the
proposed take number of 136 is a small number. There is no abundance
information available for any Alaskan stock of beaked whale. However,
the take numbers are sufficiently small (ranging from 29-120) that we
can safely assume that they are small relative to any reasonable
assumption of likely population abundance for these stocks. As an
example, we review available abundance information for other stocks of
Cuvier's beaked whales, which is widely distributed throughout deep
waters of all oceans and is typically the most commonly encountered
beaked whale in its range. Where some degree of bias correction, which
is critical to an accurate abundance estimate for cryptic species like
beaked whales, is incorporated to the estimate, we see typical
estimates in the thousands of animals, demonstrating that the take
numbers proposed for authorization are reasonably considered small.
Current abundance estimates include the Western North Atlantic stock
(5,744 animals; CV = 0.36), the Hawaii Pelagic stock (4,431 animals, CV
= 0.41), and the California/Oregon/Washington stock (3,274 animals; CV
= 0.67).
For the southeast Alaska stock of harbor porpoise, whose range is
defined as from Dixon Entrance to Cape Suckling (including inland
waters), the SAR describes a partial abundance estimate, covering
inland waters but not coastal waters, totaling 1,354 porpoise. This
most recent abundance estimate is based on survey effort in inland
waters during 2010-12 (Dahlheim et al., 2015). An older abundance
estimate, based on survey effort conducted in 1997, covering both
coastal and inland waters of the stock's range, provides a more
complete abundance estimate of 11,146 animals (Hobbs and Waite, 2010).
This
[[Page 30033]]
estimate is sufficient to demonstrate that the take number proposed for
authorization (1,016) is small.
For the potentially affected stocks of killer whale, it would be
unreasonable to assume that all takes would accrue to any one stock.
Although the Gulf of Alaska, Aleutian Islands, and Bering Sea (GOA/
BSAI) transient stock could occur in southeast Alaska, it is unlikely
that any significant proportion of encountered whales would belong to
this stock, which is generally considered to occur mainly from Prince
William Sound through the Aleutian Islands and Bering Sea. Transient
killer whales in Canadian waters are considered part of the West Coast
transient stock, further minimizing the potential for encounter with
the GOA/BSAI transient stock. We assume that only nominal, if any, take
would actually accrue to this stock. Similarly, the offshore stock is
encountered only rarely compared with resident and transient stocks.
Seasonal sighting data collected in southeast Alaska waters between
1991 and 2007 shows a ratio of offshore and resident killer whale
sightings of 0.05 (Dahlheim et al., 2009), and it is unlikely that any
amount of take accruing to this stock would exceed small numbers. We
anticipate that most killer whales encountered would be transient or
resident whales. For the remaining stocks, we assume that take would
accrue to each stock in a manner roughly approximate to the stocks'
relative abundances, i.e., 78 percent Alaska resident, 12 percent West
Coast transient, and 10 percent northern resident. This would equate to
approximately 226 takes from the Alaska resident stock (9.6 percent of
the stock abundance); 35 takes from the West Coast transient stock (10
percent of the stock abundance), and 29 takes from the northern
resident stock (9.6 percent of the stock abundance). Based on the
assumptions described in this paragraph, we preliminary find that the
taking proposed for authorization is of no greater than small numbers
for any stock of killer whale.
If all takes proposed for authorization are allotted to each
individual harbor seal stock, the estimated instances of take would be
greater than one-third of the best available abundance estimate for the
Sitka/Chatham Strait stock of harbor seal. However, similarly to the
discussion provided above for killer whale, it would be unreasonable to
assume that all takes would accrue to any one stock. Based on the
location of the proposed survey relative to the potentially affected
stocks' ranges, it is unlikely that a significant proportion of the
estimated takes would occur to the Sitka/Chatham Strait stock (whose
range just overlaps with the northern extent of the survey area) (Muto
et al., 2020). A majority of takes are likely to accrue to the Dixon/
Cape Decision stock, which most directly overlaps with the proposed
survey area. In the unlikely event that all takes occurred to the
Dixon/Cape Decision stock, the amount of take would be of small
numbers.
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 will be taken relative to the population size
of the affected species or stocks.
Unmitigable Adverse Impact Analysis and Determination
Marine mammals are legally hunted in Alaskan waters by coastal
Alaska Natives. In the GOA, the only marine mammals under NMFS'
jurisdiction that are currently hunted are Steller sea lions and harbor
seals. These species are an important subsistence resource for Alaska
Natives from southeast Alaska to the Aleutian Islands. There are
numerous communities along the shores of the GOA that participate in
subsistence hunting, including Juneau, Ketchikan, Sitka, and Yakutat in
southeast Alaska (Wolfe et al., 2013). According to Muto et al. (2019),
the annual subsistence take of Steller sea lions from the eastern stock
was 11, and 415 northern fur seals are taken annually. In addition, 340
harbor seals are taken annually (Muto et al. 2019). The seal harvest
throughout Southeast Alaska is generally highest during spring and
fall, but can occur any time of the year (Wolfe et al., 2013).
Given the temporary nature of the proposed activities and the fact
that most operations would occur further from shore, the proposed
activity would not be expected to have any impact on the availability
of the species or stocks for subsistence users. L-DEO is conducting
outreach to local stakeholders, including subsistence communities, to
notify subsistence hunters of the planned survey, to identify the
measures that would be taken to minimize any effects on the
availability of marine mammals for subsistence uses, and to provide an
opportunity for comment on these measures. During operations, radio
communications and Notice to Mariners would keep interested parties
apprised of vessel activities. NMFS is unaware of any other subsistence
uses of the affected marine mammal stocks or species that could be
implicated by this action. Therefore, NMFS has preliminarily determined
that the total taking of affected species or stocks would not have an
unmitigable adverse impact on the availability of such species or
stocks for taking for subsistence purposes. NMFS requests comments or
any information that may help to inform this determination.
Endangered Species Act (ESA)
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.
NMFS is proposing to authorize take of blue whales, fin whales, sei
whales, sperm whales, Mexico DPS humpback whales, western DPS Steller
sea lions, and WNP gray whales, which are listed under the ESA. The
NMFS OPR Permits and Conservation Division has requested initiation of
Section 7 consultation with the NMFS OPR ESA Interagency Cooperation
Division for the issuance of this IHA. NMFS will conclude the ESA
consultation prior to reaching a determination regarding the proposed
issuance of the authorization.
Proposed Authorization
As a result of these preliminary determinations, NMFS proposes to
issue an IHA to L-DEO for conducting a marine geophysical survey in the
northeast Pacific beginning in July 2021, provided the previously
mentioned mitigation, monitoring, and reporting requirements are
incorporated. A draft of the proposed IHA can be found at
<a href="http://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act">www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act</a>.
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
geophysical survey. We also request at this time 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, one-year
Renewal IHA following notice to the public providing
[[Page 30034]]
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:
<bullet> 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 one year from
expiration of the initial IHA);
<bullet> 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.
<bullet> 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: May 28, 2021.
Catherine Marzin,
Acting Director, Office of Protected Resources, National Marine
Fisheries Service.
[FR Doc. 2021-11718 Filed 6-3-21; 8:45 am]
BILLING CODE 3510-22-P
[…truncated; see source link]Indexed from Federal Register on June 4, 2021.
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