[Federal Register Volume 84, Number 68 (Tuesday, April 9, 2019)]
[Notices]
[Pages 14200-14240]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2019-06886]
[[Page 14199]]
Vol. 84
Tuesday,
No. 68
April 9, 2019
Part II
Department of Commerce
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National Oceanic and Atmospheric Administration
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Takes of Marine Mammals Incidental to Specified Activities; Taking
Marine Mammals Incidental to a Marine Geophysical Survey in the Gulf of
Alaska; Notice
Federal Register / Vol. 84 , No. 68 / Tuesday, April 9, 2019 /
Notices
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DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
RIN 0648-XG736
Takes of Marine Mammals Incidental to Specified Activities;
Taking Marine Mammals Incidental to a Marine Geophysical Survey in the
Gulf of Alaska
AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and
Atmospheric Administration (NOAA), Commerce.
ACTION: Notice; proposed incidental harassment authorization; request
for comments on proposed authorization and possible renewal.
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SUMMARY: NMFS has received a request from the Lamont-Doherty Earth
Observatory of Columbia University (L-DEO) for authorization to take
marine mammals incidental to a marine geophysical survey in the Gulf of
Alaska. Pursuant to the Marine Mammal Protection Act (MMPA), NMFS is
requesting comments on its proposal to issue an incidental harassment
authorization (IHA) to incidentally take marine mammals during the
specified activities. NMFS is also requesting comments on a possible
one-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 May 9,
2019.
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 [email protected].
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. Attachments
to electronic comments will be accepted in Microsoft Word or Excel or
Adobe PDF file formats only. All comments received are a part of the
public record and will generally be posted online at https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act without change. All personal identifying
information (e.g., name, address) voluntarily submitted by the
commenter may be publicly accessible. Do not submit confidential
business information or otherwise sensitive or protected information.
FOR FURTHER INFORMATION CONTACT: Gray Redding, 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: https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-research-and-other-activities. 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 such 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 such 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
incidental harassment authorization) with respect to potential impacts
on the human environment.
Accordingly, NMFS plans to adopt the National Science Foundation's
(NSF) EA, provided our independent evaluation of the document finds
that it includes adequate information analyzing the effects on the
human environment of issuing the IHA. NMFS is a cooperating agency on
NSF's EA. NSF's EA will be made available for public comment at https://www.nsf.gov/geo/oce/envcomp/ on approximately April 1, 2019. 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 November 20, 2018, NMFS received a request from L-DEO for an IHA
to take marine mammals incidental to conducting seismic geophysical
surveys in the Gulf of Alaska along the Alaska Peninsula subduction
zone. On December 19, 2018, NMFS received a revised copy of the
application, and that application was deemed adequate and complete on
February 11, 2019. L-DEO's request is for take of a small number of 21
marine mammal species by Level B harassment and Level A harassment.
Underwater sound associated with airgun use may result in the
behavioral harassment or auditory injury of marine mammals in the
ensonified areas. Neither L-DEO nor NMFS expects serious injury or
mortality to result from this activity and, therefore, an IHA is
appropriate.
NMFS previously issued an IHA to L-DEO for similar work (76 FR
38621; July 1, 2011). L-DEO complied with all the requirements (e.g.,
mitigation, monitoring, and reporting) of the previous IHA and
information regarding their monitoring results may be found in the
``Description of Marine Mammals in the Area of Specified Activities.''
Description of Proposed Activity
Overview
The specified activity consists of a high energy geophysical
seismic survey conducted in a portion of the Gulf of
[[Page 14201]]
Alaska. Researchers from Lamont-Doherty Earth Observatory (L-DEO),
Cornell University, Colgate University, University of Washington,
University of California Santa Cruz, University of Colorado Boulder,
University of New Mexico, Washington University in St. Louis, and the
United States Geological Survey (USGS), with funding from NSF, propose
to conduct the seismic survey from the Research Vessel (R/V) Marcus G.
Langseth (Langseth) in the Gulf of Alaska during 2019. The NSF-owned
Langseth is operated by Columbia University's L-DEO under an existing
Cooperative Agreement. The proposed seismic survey would likely occur
off the Alaska Peninsula and the eastern Aleutian islands during late
spring 2019 and would use a 36-airgun towed array with a total
discharge volume of ~6600 in\3\. The survey would take place within the
U.S. Exclusive Economic Zone (EEZ), in water ~15 to ~6,184 m deep.
The main goal of L-DEO's proposed seismic program is to conduct a
2D survey along the Alaska Peninsula subduction zone using airguns. The
addition of active sources (airguns) to the existing seismic monitoring
equipment in place would directly contribute to the overall project
goals of imaging the architecture for the subduction zone and
understanding the structures controlling how and where the planet's
largest earthquakes occur.
Dates and Duration
The survey is expected to consist of up to 18 days of seismic
operations and ~1 day of transit. The Langseth would leave from and
return to port in Kodiak, likely during late spring (end of May/early
June) 2019. Tentative sail dates are 1-19 June 2019.
Timing of the proposed survey will take advantage of the Alaska
Amphibious Community Seismic Experiment (AACSE), which has deployed 75
ocean bottom seismometers (OBSs) offshore of the Alaska Peninsula. The
survey needs to be conducted while the AACSE OBSs are on the sea floor
(before 6 August 2019). The most value-added time window is mid-May
through mid-June, when an on-shore seismic array, consisting of 400-450
onshore seismometers will also be deployed on Kodiak Island and which
could record an unprecedented ship-to-shore dataset.
Specific Geographic Region
The proposed survey would occur within the area of ~52-58[deg] N,
~150-162[deg] W, within the EEZ of Alaska in water depths ranging from
~15 to ~6184 m. Representative survey tracklines are shown in Figure 1.
As described further in this document, however, deviation in actual
track lines, including 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. Thus, within the constraints of any federal authorizations
issued for the activity, tracklines may shift from those shown in the
application and could occur anywhere within the coordinates noted above
and illustrated by the box in the inset map on Figure 1 of the IHA
application.
[GRAPHIC] [TIFF OMITTED] TN09AP19.000
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Detailed Description of Specific Activity
The procedures to be used for the proposed surveys 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 Langseth, which is owned by NSF and operated on its behalf
by Columbia University's L-DEO. The Langseth would deploy an array of
36 airguns as an energy source with a total volume of ~6,600 in\3\. The
receiving system would consist of previously deployed OBSs and onshore
seismometers (See Figure 2 in IHA Application), as well as a single
hydrophone streamer 5 kilometers (km) in length; no hydrophone streamer
would be towed during the survey. As the airgun arrays are towed along
the survey lines, the seismometers would receive and store the
returning acoustic signals internally for later analysis and the
hydrophone streamer would transfer the data to the on-board processing
system.
For this proposed survey, a total of ~4400 km of transect lines
would be surveyed in the Gulf of Alaska (GOA). There could be
additional seismic operations associated with turns, airgun testing,
and repeat coverage of any areas where initial data quality is sub-
standard. To account for unanticipated delays, 25 percent has been
added in the form of operational days, which is equivalent to adding 25
percent to the proposed line km to be surveyed. During the survey,
approximately 13 percent of the line km would take place in shallow
water (<100 meter (m)), 27 percent would occur in intermediate water
depths (100-1000 m), and the rest (60 percent) would occur in deep
water (>1000 m).
In addition to the operations of the airgun array, the ocean floor
would be mapped with a Kongsberg EM 122 multibeam echosounder (MBES)
and a Knudsen Chirp 3260 sub-bottom profiler (SBP). A Teledyne RDI 75
kilohertz (kHz) Ocean Surveyor Acoustic Doppler Current Profiler (ADCP)
would be used to measure water current velocities. These sources would
be operated from the Langseth continuously during the seismic survey,
but not during transit to and from the survey areas. All planned
geophysical data acquisition activities would be conducted by L-DEO
with on-board assistance by the scientists who have proposed the
studies. The vessel would be self-contained, and the crew would live
aboard the vessel.
During the survey, the Langseth would tow the full array,
consisting of four strings with 36 airguns (plus 4 spares) and a total
volume of ~6,600 in\3\. The 4-string array would be towed at a depth of
12 m, and the shot intervals would be 399.3 m for the entire survey.
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's Stock Assessment Reports (SAR; https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments) and more general information about these species
(e.g., physical and behavioral descriptions) may be found on NMFS's
website (https://www.fisheries.noaa.gov/find-species).
Table 1 lists all species with expected potential for occurrence in
the Gulf of Alaska and summarizes information related to the population
or stock, including regulatory status under the MMPA and ESA and
potential biological removal (PBR), where known. For taxonomy, we
follow Committee on Taxonomy (2017). 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 as gross indicators of the status of the species and
other threats.
Sixteen species of cetaceans and five species of pinnipeds could
occur in the proposed Gulf of Alaska survey area. Cetacean species
include seven species of mysticetes (baleen whales) and nine species of
odontocetes (dolphins and small and large toothed whales).
Ferguson et al. (2015) described Biological Important Areas (BIAs)
for cetaceans in the Gulf of Alaska. BIAs were delineated for four
baleen whale species and one toothed whale species including fin, gray,
North Pacific right, and humpback whales, and belugas in U.S. waters of
the Gulf of Alaska. BIAs are described in the following sections for
each marine mammal species, except for beluga whale BIAs, as these do
not co-occur within L-DEO's proposed survey area and the species is not
expected to be present there. BIAs are delineated for feeding,
migratory corridors, and small and resident populations. Supporting
evidence for these BIAs came from aerial-, land-, and vessel-based
surveys; satellite tagging data; passive acoustic monitoring;
traditional ecological knowledge; photo- and genetic-identification
data; whaling data, including catch and sighting locations and stomach
contents; prey studies; and observations from fishermen.
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's 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, stock abundance estimates are
not available, and survey abundance estimates are used. This survey
area may or may not align completely with a stock's geographic range as
defined in the SARs. For some species, this geographic area may extend
beyond U.S. waters. All managed stocks in this region are assessed in
NMFS's U.S. Alaska and U.S. Pacific SARs (e.g., Muto et al. 2018,
Carretta et al. 2018). All values presented in Table 1 are the most
recent available at the time of publication and are available in the
2017 SARs (Muto et al. 2018, Carretta et al. 2018) and draft 2018 SARs
(available online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/draft-marine-mammal-stock-assessment-reports).
[[Page 14203]]
Table 1--Marine Mammals That Could Occur in the Project Area During the Specified Activity
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ESA/MMPA Stock abundance (CV,
status; Nmin, most recent Annual M/SI
Common name Scientific name Stock strategic (Y/N) abundance survey) PBR \3\
\1\ \2\
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Order Cetartiodactyla--Cetacea--Superfamily Mysticeti (baleen whales)
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Family Eschrichtiidae:
Gray whale.................... Eschrichtius Eastern North -, -, N 26,960 (0.05, 801................. 138
robustus. Pacific. 25,849, 2016).
Western North E, D, Y 175 (0.05, 167, 0.07................ UNK
Pacific. 2016).
Family Balaenidae:
North Pacific right whale..... Eubalaena japonica.. Eastern North E, D, Y 31 (0.226, 26, 2015) 0.05 b.............. 0
Pacific.
Family Balaenopteridae (rorquals):
Blue whale.................... Balaenoptera Eastern North E, D, Y 1,647 (0.07, 1,551, 2.3................. >=0.2
musculus. Pacific. 2011).
Central North E, D, Y 133 (1.09, 63, 2010) 0.1................. 0
Pacific.
Fin whale * \4\............... Balaenoptera Northeast Pacific... E, D, Y 3,168 \4\........... 5.1................. 0.6
physalus.
Sei whale..................... Balaenoptera Eastern North E, D, Y 519 (0.4, 374, 2014) 0.75................ 0
borealis. Pacific.
Minke whale * \5\............. Balaenoptera Alaska.............. -, -, N 1,233 \5\........... UND................. 0
acutorostrata.
Humpback whale................ Megaptera Central North -, -, Y 10,103 (0.3, 7,890, 83.................. 25
novaeangliae. Pacific. 2006).
Western North E, D, Y 1,107 (0.3, 865, 3................... 3.2
Pacific. 2006).
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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 N/A (see SAR, N/A, see SAR............. 4.4
macrocephalus. 2015).
Family Ziphiidae (beaked whales):
Cuvier's beaked whale......... Ziphius cavirostris. Alaska.............. -, -, N N/A (see SAR, N/A, UND................. 0
see SAR).
Baird's beaked whale.......... Berardius bairdii... Alaska.............. -, -, N N/A (see SAR, N/A, UND................. 0
see SAR).
Stejneger's beaked whale...... Mesoplodon Alaska.............. -, -, N N/A (see SAR, N/A, UND................. 0
stejnegeri. see SAR).
Family Delphinidae:
Killer whale.................. Orcinus orca........ Eastern North -, -, N 2,347 c (N/A, 2347, 24.................. 1
Pacific Alaska 2012).
Resident.
Gulf of Alaska, -, -, N 587 c (N/A, 587, 5.87................ 1
Aleutian Islands, 2012).
and Bering Sea
Transient.
AT1 Transient....... -, D, Y 7 c (N/A, 7, 2017).. 0.01................ 0
Offshore............ -, -, N 240 (0.49, 162, 1.6................. 0
2014).
Risso's dolphin............... Grampus griseus..... CA/WA/OR............ -, -, N 6,336 (0.32, 4,817, 46.................. >=3.7
2014).
Pacific white[dash]sided Lagenorhynchus North Pacific....... -, -, N 26,880 (N/A, N/A, UND................. 0
dolphin. obliquidens. 1990).
Family Phocoenidae (porpoises):
Harbor porpoise............... Phocoena phocoena... GOA................. -, -, Y 31,046 (0.214, N/A, UND................. 72
1998).
Southeast Alaska.... -, -, Y see SAR (see SAR, 8.9................. 34
see SAR, 2012).
Dall's porpoise............... Phocoenoides dalli.. Alaska.............. -, -, N 83,400 (0.097, N/A, UND................. 38
1991).
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Order Carnivora--Superfamily Pinnipedia
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Family Otariidae (eared seals and
sea lions):
Steller sea lion.............. Eumetopias jubatus.. Eastern U.S......... T, D, Y 41,638 a (see SAR, 2,498............... 108
41,638, 2015).
Western U.S......... E, D, Y 54,267 a (see SAR, 326................. 252
54,267, 2017).
California sea lion........... Zalophus U.S................. -, -, N 296,750 (N/A, 9,200............... 389
californianus. 153,337, 2011).
Northern fur seal............. Callorhinus ursinus. Eastern Pacific..... -, D, Y 620,660 (0.2, 11,295.............. 457
525,333, 2016).
Family Phocidae (earless seals):
Northern elephant seal........ Mirounga California Breeding. -, -, N 179,000 (N/A, 4,882............... 8.8
angustirostris. 81,368, 2010).
Harbor seal................... Phoca vitulina...... South Kodiak........ -, -, N 19,199 (see SAR, 314................. 128
17,479, 2011).
Cook Inlet/Shelikof -, -, N 27,386 (see SAR, 770................. 234
Strait. 25,651, 2011).
Prince William -, -, N 29,889 (see SAR, 838................. 279
Sound?. 27,936, 2011).
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* Stocks marked with an asterisk are addressed in further detail in text below.
\1\ 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 online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments assessments. CV is coefficient of variation; Nmin is the minimum estimate of stock abundance. In some cases, CV is not applicable (N/A).
\3\ These values, found in NMFS's SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined (e.g.,
commercial fisheries, ship strike).
\4\ Uncorrected estimate from Rone et al. (2017) based on a series of line-transect surveys off of Kodiak Island. The maximum estimate from the three
surveys was selected. Based on the limited footprint of the surveys that lead to this estimate, the true abundance of the stock is expected to be much
higher.
[[Page 14204]]
\5\ Uncorrected estimate from Zerbini et al., (2006) based on a partial line-transect survey of the Gulf of Alaska.
Note--Italicized species or stocks are not expected to be taken or proposed for authorization.
All species that could potentially occur in the proposed survey
areas are included in Table 1. With the exception of AT1 transient
killer whales, these species or stocks temporally and spatially co-
occur with the activity to the degree that take is reasonably likely to
occur. However, the spatial occurrence of the AT1 transient is such
that take is not expected to occur, and they are not discussed further
beyond the explanation provided here.
AT1 transient killer whales are a small, genetically distinct
population of transient ecotype killer whales found in the Gulf of
Alaska (Matkin et al. 1999). The population has declined from a size of
22 whales in 1984, to just 7 today, and it is believed this decline was
associated with the Exxon Valdez Oil Spill in 1989 (Matkin et al.
2008). AT1 transients have only ever been seen in Prince William Sound
and in the Kenai Fjords region (Muto et al. 2018; Matkin et al. 2008).
Therefore, while the stock is present in the Gulf of Alaska, and
deserved consideration, the limited range of the stock and the fact
that this range does not overlap with L-DEO's proposed survey means
take is not likely to occur for the AT1 stock of transient killer
whales.
No comprehensive abundance estimate is available for the Alaska
stock of minke whales. The best available estimate for the area comes
from line-transect surveys 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 (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. This estimate
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, there are provisional
estimates representing relevant portions of the range. Zerbini et al.
(2006) produced an estimate of 1,652 (95 percent CI: 1,142-2,389) fin
whales for the area described above. Additionally, a series of line-
transect surveys off of Kodiak Island and the in the northern Gulf of
Alaska conducted in 2009, 2013, and 2015, generated a maximum estimate
of 3,168 (CV = 0.26) (also not been corrected for animals missed on the
trackline) (Rone et al. 2017).
Kato and Miyashita (1998) reported 102,112 sperm whales (CV =
0.155) in the western North Pacific, however, with the caveat that
their estimate is likely positively biased. From surveys in the Gulf of
Alaska in 2009 and 2015, Rone et al. (2017) estimated 129 (CV = 0.44)
and 345 sperm whales (CV = 0.43) in each year, respectively. The
overall number of sperm whales occurring in Alaska waters is unknown
(Muto et al. 2018).
For the three species of beaked whale expected to occur in the area
(Baird's, Cuvier's, and Stejneger's), there are no reliable estimates
of abundance.
We have reviewed L-DEO's species descriptions, including life
history information, distribution, regional distribution, diving
behavior, and acoustics and hearing, for accuracy and completeness.
Below, for the 21 species that are likely to be taken by the activities
described, we offer a brief introduction to the species and relevant
stock as well as available information regarding population trends and
threats, and describe any information regarding local occurrence.
In addition, the northern sea otter (Enhydra lutris) and Pacific
walrus (Odobenus rosmarus divergens) may be found in the Gulf of
Alaska. However, northern sea otter and Pacific walrus are managed by
the U.S. Fish and Wildlife Service and are not considered further in
this document.
Mysticetes
North Pacific Right Whale (Eubalaena japonica)
North Pacific right whales summer in the northern North Pacific,
primarily in the Okhotsk Sea (Brownell et al. 2001) and in the Bering
Sea (Shelden et al. 2005; Wade et al. 2006). This species is divided
into western and eastern North Pacific stocks. The eastern North
Pacific stock that occurs in U.S. waters numbers only ~31 individuals
(Wade et al. 2011b), and critical habitat has been designated in the
eastern Bering Sea and in the GOA, south of Kodiak Island (NMFS 2017b).
Wintering and breeding areas are unknown, but have been suggested to
include the Hawaiian Islands, Ryukyu Islands, and Sea of Japan (Allen
1942; Banfield 1974; Gilmore 1978; Reeves et al. 1978; Herman et al.
1980; Omura 1986).
Since the 1960s, North Pacific right whale sightings have been
relatively rare (e.g., Clapham et al. 2004; Shelden et al. 2005). In
the eastern North Pacific, south of 50 [deg]N, only 29 reliable
sightings were recorded from 1900 to 1994 (Scarff 1986, 1991; Carretta
et al. 1994). Starting in 1996, right whales have been sighted
regularly in the southeast Bering Sea, including calves in some years
(Goddard and Rugh 1998; LeDuc et al. 2001; Moore et al. 2000, 2002b;
Wade et al. 2006; Zerbini et al. 2009); they have also been detected
acoustically when sonobuoys were deployed (McDonald and Moore 2002;
Munger et al. 2003, 2005, 2008; Berchok et al. 2009). Right whales are
known to occur in the southeast Bering Sea from May to December (e.g.,
Tynan et al. 2001; Hildebrand and Munger 2005; Munger et al. 2005,
2008). Call frequencies tended to be higher in July-October than from
May-June or November-December (Munger et al. 2008). Right whales seem
to pass through the middle-shelf areas, without remaining there longer
than a few days (Munger et al. 2008).
Shelden et al. (2005) reported that the slope and abyssal plain in
the western GOA were important areas for right whales until the late
1960s, but sightings and acoustic detections in this region in recent
decades are rare. In March 1979, a group of four right whales was seen
in Yakutat Bay (Waite et al. 2003), but there were no further reports
of right whale sightings in the GOA until July 1998, when a single
whale was seen southeast of Kodiak Island (Waite et al. 2003). Three
sightings and one acoustic detection of right whales were made in
Barnabas Trough south of Kodiak Island during NOAA surveys in 2004 to
2006 in areas with high densities of zooplankton (Wade et al. 2011a).
Those authors also report a fourth opportunistic sighting by a
commercial fisher during that time in the same area. One right whale
was sighted in the Aleutian Islands south of Unimak Pass in September
2004 (Wade et al. 2011b). A BIA for feeding for North Pacific right
whales was designated east of the Kodiak Archipelago, encompassing the
GOA critical habitat and extending south of 56[deg] N and north of
58[deg] N and beyond the shelf edge (Ferguson et al. 2015). Feeding
primarily occurs in this BIA between June and September (Ferguson et
al. 2015)
Right whale acoustic detections were made south of the Alaska
Peninsula and to the east of Kodiak Island in 2000 during August and
September (see
[[Page 14205]]
Waite et al. 2003; Mellinger et al. 2004b), but no acoustic detections
were made from April to August 2003 (Munger et al. 2008) or in April
2009 (Rone et al. 2010). Three right whales were acoustically detected
in the Barnabas Trench area during a towed-PAM survey of the U.S. Navy
training area east of Kodiak in the summer of 2013 but none were
observed visually (Rone et al. 2014). Right whales were not
consistently detected acoustically from (2011-2015) with the fixed PAM
monitoring in this region (Baumann-Pickering et al. 2012; Debich et al.
2013; Rice et al. 2015), but there were detections on two days in June
and August 2013 (Debich et al. 2014). No right whales were visually
observed during the three years of surveys (2009, 2013, and 2015) in
this military area east of Kodiak (Rone et al. 2017). There was one
sighting of a single North Pacific right whale during the L-DEO seismic
survey conducted in the summer of 2011 in the same area as the
currently proposed survey (RPS 2011). There was another sighting of a
lone North Pacific right whale during a marine mammal cruise,
approximately 130 miles east of Kodiak Island in July 2012 (Matsuoka et
al. 2013). Thus, it is possible that a right whale could be seen during
the proposed survey.
Gray Whale (Eschrichtius robustus)
Two separate populations of gray whales have been recognized in the
North Pacific (LeDuc et al. 2002): The eastern North Pacific and
western North Pacific (or Korean-Okhotsk) stocks. However, the
distinction between these two populations has been recently debated
owing to evidence that whales from the western feeding area also travel
to breeding areas in the eastern North Pacific (Weller et al. 2012,
2013; Mate et al. 2015). Thus, it is possible that whales from both the
endangered Western North Pacific and the delisted Eastern North Pacific
distinction population segments (DPSs) could occur in the proposed
survey area in the eastern North Pacific.
Gray whale populations were severely reduced by whaling, but the
eastern North Pacific population is considered to have recovered. Punt
and Wade (2012) estimated the eastern North Pacific population to be at
85 percent of its carrying capacity in 2009. The eastern North Pacific
gray whale breeds and winters in Baja, California, and migrates north
to summer feeding grounds in the northern Bering Sea, Chukchi Sea, and
western Beaufort Sea (Rice and Wolman 1971; Rice 1998; Jefferson et al.
2015). Most of the eastern Pacific population makes a round-trip annual
migration of more than 18,000 km. From late May to early October, the
majority of the population concentrates in the northern and western
Bering Sea and in the Chukchi Sea. However, some individuals spend the
summer months scattered along the coasts of southeast Alaska, B.C.,
Washington, Oregon, and northern California (Rice and Wolman 1971;
Nerini 1984; Darling et al. 1998; Dunham and Duffus 2001, 2002;
Calambokidis et al. 2002). Gray whales are found primarily in shallow
water; most follow the coast during migration, staying close to the
shoreline except when crossing major bays, straits, and inlets (Braham
1984).
It is difficult to determine precisely when the southbound
migration begins; whales near Barrow were moving predominantly south in
August (Maher 1960; Braham 1984). Gray whales leave the Bering Sea
through Unimak Pass from late October through January (Braham 1984).
From October to January, the main part of the population moves down the
west coast of North America. Rugh et al. (2001) analyzed data collected
from two sites in California to estimate the timing of the gray whale
southward migration. They estimated that the median date for the
migration past various sites was 1 December in the central Bering Sea
(a nominal starting point), 12 December at Unimak Pass, 18 December at
Kodiak Island, and 5 January for Washington.
By January and February, most of the whales are concentrated in the
lagoons along the Pacific coast of the Baja Peninsula, Mexico. From
late February to June, the population migrates northward to arctic and
subarctic seas (Rice and Wolman 1971). The peak of northward migration
in the GOA occurs in mid-April (Braham 1984). Most gray whales follow
the coast during migration and stay within 2 km of the shoreline,
except when crossing major bays, straits, and inlets from southeast
Alaska to the eastern Bering Sea (Braham 1984). Gray whales use the
nearshore areas of the Alaska Peninsula during the spring and fall
migrations, and are often found within the bays and lagoons, primarily
north of the peninsula, during the summer (Brueggeman et al. 1989 in
Waite et al. 1999). However, gray whales are known to move further
offshore between the entrance to Prince William Sound (PWS) and Kodiak
Island and between Kodiak Island and the southern part of the Alaska
Peninsula (Consiglieri et al. 1982). During May-October, primary
occurrence extends seaward 28 km from the shoreline. This is the main
migratory corridor for gray whales.
In the summer, gray whales are seen in the southeast Bering Sea
(Moore et al. 2002b) and in the GOA, including around Kodiak Island
(e.g., Wade et al. 2003; Calambokidis et al. 2004; Calambokidis 2007;
Moore et al. 2007). In fact, gray whales have been seen feeding off
southeast Kodiak Island, in particular near Ugak Bay, year-round (Moore
et al. 2007). Moore et al. (2007) noted monthly sighting rates that
exceeded 100 sightings/h in January, June, September, and November, and
>20 sightings/h in most other months. One feeding aggregation in July
consisted of 350-400 animals, clustered in groups of 10-20 animals,
from the mouth of Ugak Bay to 100 km ESE of Ugak Island (Moore et al.
2007). Wade et al. (2003) reported a group size of 5.6 in the western
GOA. A biologically important area (BIA) for feeding for gray whales
has been identified in the waters east of the Kodiak Archipelago, with
the greatest densities of gray whales occurring from June through
August (Ferguson et al. 2015). Additionally, a gray whale migratory
corridor BIA has been established extending from Unimak Pass in the
western GOA to the Canadian border in the eastern GOA (Ferguson et al.
2015), including much of the landward side of the survey area. Gray
whales occur in this area in high densities during November through
January (southbound) and March through May (northbound).
Rone et al. (2017) sighted gray whales off Ugak Island, Kodiak, in
all three years (2009, 2013, and 2015) of surveys in the military
training area east of Kodiak. Gray whales were detected acoustically
throughout the summer and fall at fixed hydrophones on the shelf off
Kenai Peninsula and near Kodiak Island in this military training area
in a 2014-2015 study (Rice et al. 2015), but they were not detected at
deeper slope or seamount sites and they were detected only once in
prior years of study from 2011 to 2013 (Baumann-Pickering et al. 2012;
Debich et al. 2013). Gray whales were neither observed visually nor
detected acoustically during the L-DEO seismic survey conducted in the
summer of 2011 in the same area as the currently proposed survey (RPS
2011). Gray whales could be encountered during the proposed seismic
survey in the GOA.
Humpback Whale (Megaptera novaeangliae)
The humpback whale is found throughout all oceans of the World
(Clapham 2009), with recent genetic evidence suggesting three separate
subspecies: North Pacific, North Atlantic, and Southern Hemisphere
[[Page 14206]]
(Jackson et al. 2014). Nonetheless, genetic analyses suggest some gene
flow (either past or present) between the North and South Pacific
(e.g., Jackson et al. 2014; Bettridge et al. 2015). Although considered
to be mainly a coastal species, the humpback whale often traverses deep
pelagic areas while migrating (e.g., Mate et al. 1999; Garrigue et al.
2015).
North Pacific humpback whales migrate between summer feeding
grounds along the Pacific Rim and the Bering and Okhotsk seas and
winter calving and breeding areas in subtropical and tropical waters
(Pike and MacAskie 1969; Rice 1978; Winn and Reichley 1985;
Calambokidis et al. 2000, 2001, 2008). In the North Pacific, humpbacks
winter in four different breeding areas: (1) Along the coast of Mexico;
(2) along the coast of Central America; (3) around the Main Hawaiian
Islands; and (4) in the western Pacific, particularly around the
Ogasawara and Ryukyu islands in southern Japan and the northern
Philippines (Calambokidis et al. 2008; Fleming and Jackson 2011;
Bettridge et al. 2015). These breeding areas are recognized as the
Mexico, Central America, Hawaii, and Western Pacific DPSs (NMFS 2016b).
Hawaii is the primary wintering area for whales from summer feeding
areas in the Gulf of Alaska (Calambokidis et al. 2008). Individuals
from the Hawaii, Western Pacific, and Mexico DPSs could occur in the
proposed survey area to feed. The Hawaii DPS is not listed and the
Mexico DPS is listed as threatened under the ESA. Additionally, the
Western North Pacific stock, analogous to the western Pacific DPS, is
listed as endangered under the ESA.
There is potential for mixing of the western and eastern North
Pacific humpback populations on their summer feeding grounds, and
several sources suggest that this occurs to a limited extent (Muto et
al. 2018). NMFS is currently reviewing the global humpback whale stock
structure in light of the recent revision to their ESA listing and
identification of 14 DPSs (81 FR 62259; 8 September 2016). Currently,
two stocks of humpback whales are recognized as occurring in Alaskan
waters. The Central North Pacific Stock occurs from southeast Alaska to
the Alaska Peninsula and the Western North Pacific Stock occurs from
the Aleutians to the Bering Sea and Russia. These two stocks overlap on
feeding grounds in the eastern Bering Sea and the western Gulf of
Alaska (Muto et al. 2018), encompassing the entire proposed survey
area. BIAs for humpback whale feeding have been designated surrounding
Kodiak Island and the Shumagin Islands (Ferguson et al. 2015). The
highest densities of humpback whales occur during July through
September around Kodiak Island and during July through August in the
Shumagin Islands.
Humpback whales are commonly sighted within the proposed survey
area. Waite (2003) reported that 117 humpbacks were seen in 41 groups
during their surveys in the western GOA in 2003, with aggregations seen
off northeast Kodiak Island. During summer surveys from the Kenai
Fjords to the central Aleutian Islands in 2001-2003, humpbacks were
most abundant near Kodiak Island, the Shumagin Islands, and north of
Unimak Pass (Zerbini et al. 2006). Sightings of humpbacks around the
Kodiak Islands were made most frequently in the fall, and aggregations
were seen off Shuyak and Sitkalidak islands (Wynne and Witteveen 2005),
as well as in Marmot and Chiniak bays (Baraff et al. 2005). Waite et
al. (1999) noted another aggregation area north of Unalaska Island.
Offshore sightings of humpbacks have also been made south of the Alaska
Peninsula, including ~280 km south of the Shumagin Islands (e.g.,
Forney and Brownell 1996; Waite et al. 1999). Humpback whales were
sighted a total of 220 times (637 animals) during the three years of
surveys (2009, 2013, and 2015) in and near the U.S. Navy training area
east of Kodiak (Rone et al. 2017). Humpback whales were also frequently
detected acoustically during all years (2011-2015) of fixed-PAM studies
in this area, with peak detections during late fall through early
winter and detections at all shelf, slope, and seamount sites (Baumann-
Pickering et al. 2012; Debich et al. 2013; Rice et al. 2015). Humpback
whales were the most frequently sighted cetacean during the L-DEO
seismic survey conducted in the summer of 2011 in the same area as the
currently proposed survey, comprising 50 percent of all cetacean
sightings (RPS 2011). There were 92 sightings of this species,
representing 288 animals during the 37 days of monitoring. The average
group size was three and the maximum group size was 37. This species is
likely to be common in the proposed survey area.
Calambokidis et al. (2008) reported an abundance estimate of 3,000-
5,000 for the GOA. Rone et al. (2017) calculated an abundance estimate
of 2,215 (uncorrected for missed animals) from a June-July 2013 survey
in the U.S. Navy training area east of Kodiak Island, with the bulk of
this estimate (2,927) found in the inshore stratum. NMFS provides best
estimates of 1,107 for the Western North Pacific Stock and 10,103 for
the Central North Pacific Stock (Muto et al. 2018). Within the Central
North Pacific stock, the Hawaii DPS is estimated to contain 11,398
animals where the Mexico DPS is estimated to contain 3,264 animals (81
FR 62259; effective October 11, 2016).
Minke Whale (Balaenoptera acutorostrata)
The minke whale has a cosmopolitan distribution ranging from the
tropics and subtropics to the ice edge in both hemispheres (Jefferson
et al. 2015). In the Northern Hemisphere, minke whales are usually seen
in coastal areas, but can also be seen in pelagic waters during
northward migrations in spring and summer, and southward migration in
autumn (Stewart and Leatherwood 1985). In the North Pacific, the summer
range extends to the Chukchi Sea; in the winter, minke whales move
further south to within 2[deg] of the Equator (Perrin and Brownell
2009). The International Whaling Commission (IWC) recognizes three
stocks in the North Pacific: The Sea of Japan/East China Sea, the rest
of the western Pacific west of 180[deg]N, and the remainder of the
Pacific (Donovan 1991). NMFS recognizes a single stock in Alaskan
waters and a second California/Oregon/Washington Stock (Muto et al.
2016).
The minke whale tends to be solitary or in groups of 2-3 but can
occur in much larger aggregations around prey resources (Jefferson et
al. 2008). Predominantly solitary animals were seen during surveys in
Alaska (Wade et al. 2003; Waite 2003; Zerbini et al. 2006). The small
size, inconspicuous blows, and brief surfacing times of minke whales
mean that they are easily overlooked in heavy sea states, although they
are known to approach vessels in some circumstances (Stewart and
Leatherwood 1985). Little is known about the diving behavior of minke
whales, but they are not known to make prolonged deep dives
(Leatherwood and Reeves 1983).
Minke whales are relatively common in the Bering and Chukchi seas
and in the inshore waters of the GOA (Mizroch 1992), but they are not
considered abundant in any other part of the eastern Pacific
(Brueggeman et al. 1990). Waite (2003) sighted four minke whales in
three groups during surveys in the western GOA in 2003, south of the
Kenai Peninsula and south of PWS. Moore et al. (2002b) reported a minke
whale sighting south of the Sanak Islands. Baraff et al. (2005)
reported a single sighting near Kodiak Island in July 2002. During
surveys in the western GOA and eastern Aleutians, minke whales occurred
primarily in the Aleutians; a few sightings were made
[[Page 14207]]
south of the Alaska Peninsula and near Kodiak Island (Zerbini et al.
2006). Rone et al. (2017) reported two sightings totaling three minke
whales in 2009, three sightings totaling six minke whales in 2013, and
no sightings of minke whales in 2015 in the U.S. Navy training area
east of Kodiak. Minke whales were not detected acoustically during any
year (2011-2015) of the fixed-PAM studies in the Department of the Navy
(DoN) area east of Kodiak (Baumann-Pickering et al. 2012; Debich et al.
2013; Rice et al. 2015). There was one sighting of a single minke whale
during the L-DEO seismic survey conducted in the summer of 2011 in the
same area as the currently proposed survey (RPS 2011).
Sei Whale (Balaenoptera borealis)
The sei whale occurs in all ocean basins (Horwood 2009) but appears
to prefer mid-latitude temperate waters (Jefferson et al. 2015). It
undertakes seasonal migrations to feed in subpolar latitudes during
summer and returns to lower latitudes during winter to calve (Horwood
2009). The sei whale is pelagic and generally not found in coastal
waters (Harwood and Wilson 2001). It occurs in deeper waters
characteristic of the continental shelf edge region (Hain et al. 1985)
and in other regions of steep bathymetric relief such as seamounts and
canyons (Kenney and Winn 1987; Gregr and Trites 2001). On feeding
grounds, sei whales associate with oceanic frontal systems (Horwood
1987) such as the cold eastern currents in the North Pacific (Perry et
al. 1999). Sei whales are frequently seen in groups of 2-5 (Jefferson
et al. 2008), although larger groups sometimes form on feeding grounds
(Gambell 1985a).
In the U.S. Pacific, an Eastern North Pacific and a Hawaii stock
are recognized (Carretta et al. 2017). During summer in the North
Pacific, the sei whale can be found from the Bering Sea to the northern
GOA and south to California, and in the western Pacific from Japan to
Korea. Its winter distribution is concentrated at about 20[deg] N, and
sightings have been made between southern Baja California and the Islas
Revilla Gigedo (Rice 1998). No breeding grounds have been identified
for sei whales; however, calving is thought to occur from September to
March.
Moore et al. (2002b) made four sightings of six sei whales during
summer surveys in the eastern Bering Sea, and one sighting south of the
Alaska Peninsula between Kodiak and the Shumagin Islands. No sei whales
were seen during surveys of the GOA by Wade et al. (2003), Waite
(2003), or Zerbini et al. (2006). Rone et al. (2017) reported no sei
whale sightings in 2009 or 2013 and a single sei whale sighting of one
animal in 2015 in the U.S. Navy training area east of Kodiak. There was
one sighting of two sei whales during the L-DEO seismic survey
conducted in the summer of 2011 in the same area as the currently
proposed survey (RPS 2011). During a 2012 survey in summer and early
fall, Matsuoka et al. (2013) reported 87 sei whale sightings of 1,647
individuals, however the majority of these sightings were far south of
the action area. Sei whale sightings are likely to be uncommon in the
proposed survey area.
Fin Whale (Balaenoptera physalus)
The fin whale is widely distributed in all the World's oceans
(Gambell 1985b), although it is most abundant in temperate and cold
waters (Aguilar 2009). Nonetheless, its overall range and distribution
are not well known (Jefferson et al. 2015). A recent review of fin
whale distribution in the North Pacific noted the lack of sightings
across the pelagic waters between eastern and western winter areas
(Mizroch et al. 2009). The fin whale most commonly occurs offshore but
can also be found in coastal areas (Aguilar 2009). Most populations
migrate seasonally between temperate waters where mating and calving
occur in winter, and polar waters where feeding occurs in summer
(Aguilar 2009). However, recent evidence suggests that some animals may
remain at high latitudes in winter or low latitudes in summer (Edwards
et al. 2015).
The fin whale is known to use the shelf edge as a migration route
(Evans 1987). Sergeant (1977) suggested that fin whales tend to follow
steep slope contours, either because they detect them readily, or
because the contours are areas of high biological productivity.
However, fin whale movements have been reported to be complex
(Jefferson et al. 2015). Stafford et al. (2009) noted that sea-surface
temperature is a good predictor variable for fin whale call detections
in the North Pacific.
North Pacific fin whales summer from the Chukchi Sea to California
and winter from California southwards (Gambell 1985b). In the United
States, three stocks are recognized in the North Pacific: California/
Oregon/Washington, Hawaii, and Alaska (Northeast Pacific) (Carretta et
al. 2017). Information about the seasonal distribution of fin whales in
the North Pacific has been obtained from the detection of fin whale
calls by bottom-mounted, offshore hydrophone arrays along the U.S.
Pacific coast, in the central North Pacific, and in the western
Aleutian Islands (Moore et al. 1998, 2006; Watkins et al. 2000a,b;
Stafford et al. 2007, 2009). Fin whale calls are recorded in the North
Pacific year-round, including the GOA (e.g., Moore et al. 2006;
Stafford et al. 2007, 2009; Edwards et al. 2015). Near the Alaska
Peninsula in the western GOA, the number of calls received peaked in
May-August, with few calls during the rest of the year (Moore et al.
1998). In the central North Pacific, the GOA, and the Aleutian Islands,
call rates peak during fall and winter (Moore et al. 1998, 2006;
Watkins et al. 2000a,b; Stafford et al. 2009).
Rice and Wolman (1982) encountered 19 fin whales during surveys in
the GOA, including 10 aggregated near Middleton Island on 1 July 1980.
During surveys from the Kenai Peninsula to the central Aleutian
Islands, fin whales were most abundant near the Semidi Islands and
Kodiak Island (Zerbini et al. 2006). Numerous sightings of fin whales
were also seen between the Semidi Islands and Kodiak Island during
surveys by Waite (2003). Fin whale sightings around Kodiak Island were
most numerous along the western part of the island in Uyak Bay and
Kupreanof Straits, and in Marmot Bay (Wynne and Witteveen 2005; Baraff
et al. 2005). Fin whales were sighted around Kodiak Island year-round,
but most sightings were made in the spring and summer (Wynne and
Witteveeen 2005). A BIA for fin whale feeding has been designated
southward from the Kenai Peninsula inshore of the Kodiak Archipelago
and along the Alaska Peninsula to include the Semidi Islands (Ferguson
et al. 2015), overlapping with a proportion of the proposed survey
area. Densities of fin whales are highest in this area during June
through August.
Rone et al. (2017) reported 24 fin whale sightings (64 animals) in
2009, two hundred fin whale sightings (392 animals) in 2013, and 48 fin
whale sightings (69 animals) in 2015 in the U.S. Navy training area
east of Kodiak. That study also provided an abundance estimate of 3168
for this area. The density and abundance estimates were not corrected
for missed animals. Fin whales were also frequently detected
acoustically throughout the year during all years (2011-2015) of fixed-
PAM studies in this area and detections occurred at all shelf, slope,
and seamount sites (Baumann-Pickering et al. 2012; Debich et al. 2013;
Rice et al. 2015). Fin whales were the second most frequently sighted
cetacean during the L-DEO seismic survey conducted in the summer of
2011 in the same area as the currently proposed survey, comprising
[[Page 14208]]
15.2 percent of all cetacean sightings (RPS 2011). There were 28
sightings of this species, representing 79 animals during the 37 days
of monitoring. The average group size was three and the maximum group
size was 10. Fin whales are likely to be common in the proposed survey
area.
Blue Whale (Balaenoptera musculus)
The blue whale has a cosmopolitan distribution and tends to be
pelagic, only coming nearshore to feed and possibly to breed (Jefferson
et al. 2015). Blue whale migration is less well defined than for some
other rorquals, and their movements tend to be more closely linked to
areas of high primary productivity, and hence prey, to meet their high
energetic demands (Branch et al. 2007). Generally, blue whales are
seasonal migrants between high latitudes in the summer, where they
feed, and low latitudes in the winter, where they mate and give birth
(Lockyer and Brown 1981). Some individuals may stay in low or high
latitudes throughout the year (Reilly and Thayer 1990; Watkins et al.
2000b).
Although it has been suggested that there are at least five
subpopulations in the North Pacific (Reeves et al. 1998), analysis of
calls monitored from the U.S. Navy Sound Surveillance System (SOSUS)
and other offshore hydrophones (e.g., Stafford et al. 1999, 2001, 2007;
Watkins et al. 2000a; Stafford 2003) suggests that there are two
separate populations: one in the eastern and one in the central North
Pacific (Carretta et al. 2017). The Eastern North Pacific Stock
includes whales that feed primarily off California from June-November
and winter off Central America (Calambokidis et al. 1990; Mate et al.
1999). The Central North Pacific Stock feeds off Kamchatka, south of
the Aleutians and in the Gulf of Alaska during summer (Stafford 2003;
Watkins et al. 2000b), and migrates to the western and central Pacific
(including Hawaii) to breed in winter (Stafford et al. 2001; Carretta
et al. 2017). The status of these two populations could differ
substantially, as little is known about the population size in the
western North Pacific (Branch et al. 2016).
In the North Pacific, blue whale calls are detected year-round
(Stafford et al. 2001, 2009; Moore et al. 2002a, 2006; Monnahan et al.
2014). Stafford et al. (2009) reported that sea-surface temperature is
a good predictor variable for blue whale call detections in the North
Pacific. In the GOA, no detections of blue whales had been made since
the late 1960s (NOAA 2004b; Calambokidis et al. 2009) until blue whale
calls were recorded in the area during 1999-2002 (Stafford 2003;
Stafford and Moore 2005; Moore et al. 2006; Stafford et al. 2007). Call
types from both northeastern and northwestern Pacific blue whales were
recorded from July through December in the GOA, suggesting that two
stocks used the area at that time (Stafford 2003; Stafford et al.
2007). Call rates peaked from August through November (Moore et al.
2006). More recent acoustic studies using fixed PAM have confirmed the
presence of blue whales from both the Central and Northeast Pacific
stocks in the Gulf of Alaska concurrently (Baumann-Pickering et al.
2012; Debich et al. 2013; Rice et al. 2015). Blue whale calls were
recorded in all months; at all shelf, slope, and seamount sites; and
during all years (2011-2015) of those studies.
In July 2004, three blue whales were sighted in the GOA. The first
blue whale was seen on 14 July ~185 km southeast of PWS. Two more blue
whales were seen ~275 km southeast of PWS (NOAA 2004b; Calambokidis et
al. 2009). These whales were thought to be part of the California
feeding population (Calambokidis et al. 2009). Western blue whales are
more likely to occur in the western portion of the GOA, southwest of
Kodiak, where their calls have been detected (see Stafford 2003). Two
blue whale sightings were also made in the Aleutians in August 2004
(Calambokidis et al. 2009). No blue whales were seen during surveys of
the western GOA by Zerbini et al. (2006).
Rone et al. (2017) reported no blue whale sightings in 2009, five
blue whale sightings (seven animals) in 2013, and 13 blue whale
sightings (13 animals) in 2015 in the U.S. Navy training area east of
Kodiak. Blue whales were not observed during the L-DEO seismic survey
conducted in the summer of 2011 in the same area as the currently
proposed survey (RPS 2011).
Odontocetes
Sperm Whale (Physeter macrocephalus)
The sperm whale is the largest of the toothed whales, with an
extensive worldwide distribution from the edge of the polar pack ice to
the Equator (Whitehead 2009). Sperm whale distribution is linked to its
social structure: Mixed groups of adult females and juveniles of both
sexes generally occur in tropical and subtropical waters at latitudes
less than ~40[deg] (Whitehead 2009). After leaving their female
relatives, males gradually move to higher latitudes, with the largest
males occurring at the highest latitudes and only returning to tropical
and subtropical regions to breed. Sperm whales generally are
distributed over large areas that have high secondary productivity and
steep underwater topography, in waters at least 1000 m deep (Jaquet and
Whitehead 1996). They are often found far from shore but can be found
closer to oceanic islands that rise steeply from deep ocean waters
(Whitehead 2009).
Most of the information regarding sperm whale distribution in the
GOA (especially the eastern GOA) and southeast Alaska has come from
observations from fishermen and reports from fisheries observers aboard
commercial fishing vessels (e.g., Dahlheim 1988). Fishery observers
have identified interactions (e.g., depredation) between longline
vessels and sperm whales in the GOA and southeast Alaska since at least
the mid-1970s (e.g., Hill et al. 1999; Straley et al. 2005; Sigler et
al. 2008), with most interactions occurring in the West Yakutat and
East Yakutat/Southeast regions (Perez 2006; Hanselman et al. 2008).
Sigler et al. (2008) noted high depredation rates in West Yakutat, East
Yakutat/Southeast region, as well as the central GOA. Hill et al.
(1999) found that most interactions in the GOA occurred to the east of
Kodiak Island, even though there was substantial longline effort in
waters to the west of Kodiak. Mellinger et al. (2004a) also noted that
sperm whales occurred less often west of Kodiak Island.
Sperm whales are commonly sighted during surveys in the Aleutians
and the central and western GOA (e.g., Forney and Brownell 1996; Moore
2001; Waite 2003; Wade et al. 2003; Zerbini et al. 2004; Barlow and
Henry 2005; Ireland et al. 2005; Straley et al. 2005). Waite (2003) and
Wade et al. (2003) noted an average group size of 1.2 in the western
GOA. In contrast, there are fewer reports on the occurrence of sperm
whales in the eastern GOA (e.g., Rice and Wolman 1982; Mellinger et al.
2004a; MacLean and Koski 2005; Rone et al. 2010). Rone et al. (2017)
reported no sperm whale sightings in 2009, 19 sperm whale sightings (22
animals) in 2013, and 27 sperm whale sightings (45 animals) in 2015 in
the U.S. Navy training area east of Kodiak. Additionally, there were
241 acoustic encounters with sperm whales during the 2013 towed-
hydrophone survey in that study (Rone et al. 2014). Sperm whales were
also frequently detected acoustically throughout the year during all
years (2011-2015) of fixed-PAM studies in this area and detections
occurred at all shelf, slope, and seamount sites, but they were less
common at the shelf site near Kenai Peninsula and most common on the
[[Page 14209]]
slope (Baumann-Pickering et al. 2012; Debich et al. 2013; Rice et al.
2015).
Rone et al. (2017) provided an abundance estimate (uncorrected for
missed animals) for the area of 129 sperm whales, most of which were
found in slope waters. Sperm whales were not observed during the L-DEO
seismic survey conducted in the summer of 2011 in the same area as the
currently proposed survey (RPS 2011).
Cuvier's Beaked Whale (Ziphius cavirostris)
Cuvier's beaked whale is the most widespread of the beaked whales,
occurring in almost all temperate, subtropical, and tropical waters and
even some sub-polar and polar waters (MacLeod et al. 2006). It is
likely the most abundant of all beaked whales (Heyning and Mead 2009).
Cuvier's beaked whale is found in deep water over and near the
continental slope (Jefferson et al. 2015).
Cuvier's beaked whale ranges north to the GOA, including southeast
Alaska, the Aleutian Islands, and the Commander Islands (Rice 1986,
1998). Most reported sightings have been in the Aleutian Islands (e.g.,
Leatherwood et al. 1983; Forney and Brownell 1996; Brueggeman et al.
1987). Waite (2003) reported a single sighting of four Cuvier's beaked
whales at the shelf break east of Kodiak Island during the summer of
2003 and one stranded on Kodiak Island in January 1987 (Foster and Hare
1990). There was one sighting of a single Cuvier's beaked whale during
a 2013 survey in the U.S. Navy training area east of Kodiak, but none
during the 2009 and 2015 surveys in that region (Rone et al. 2017).
There were also five sightings (eight animals) of unidentified beaked
whales during the 2013 survey and none during the other years.
Additionally, there were 34 acoustic encounters with Cuvier's beaked
whales during the 2013 towed-hydrophone survey in that study (Rone et
al. 2014). Cuvier's beaked whales were detected occasionally at deep-
water sites (900-1,000 m) during the 2011-2015 fixed-PAM studies in the
U.S. Navy training area. They were infrequently detected on the slope
site but more commonly detected at Pratt and Quinn seamounts.
Detections occurred May to July 2014 at Pratt Seamount and October 2014
to March 2015 at Quinn Seamount in one of those studies (Rice et al.
2015). Beaked whales were not observed during the L-DEO seismic survey
conducted in the summer of 2011 in the same area as the currently
proposed survey (RPS 2011).
Stejneger's Beaked Whale (Mesoplodon stejnegeri)
Stejneger's beaked whale occurs in subarctic and cool temperate
waters of the North Pacific (Mead 1989). Most records are from Alaskan
waters, and the Aleutian Islands appear to be its center of
distribution (Mead 1989; Wade et al. 2003). There have been no
confirmed sightings of Stejneger's beaked whale in the GOA since 1986
(Wade et al. 2003). However, they have been detected acoustically in
the Aleutian Islands during summer, fall, and winter (Baumann-Pickering
et al. 2014) and were detected year-round at deep-water sites during
the 2011-2015 fixed-PAM studies in the U.S. Navy training area east of
Kodiak (Baumann-Pickering et al. 2012; Debich et al. 2013; Rice et al.
2015). In contrast to Cuvier's beaked whales, which were more prevalent
at seamounts, Stejneger's beaked whales were detected most frequently
at the slope site, with peak detections in September and October
(Debich et al. 2013; Rice et al. 2015). There were no sightings of
Stejneger's beaked whales during three years of surveys (2009, 2013,
2015) in this area (Rone et al. 2017). However, there were five
sightings (eight animals) of unidentified beaked whales during the 2013
survey. Additionally, there were six acoustic encounters with
Stejneger's beaked whales during the 2013 towed-hydrophone survey in
that study (Rone et al. 2014). Beaked whales were not observed during
the L-DEO seismic survey conducted in the summer of 2011 in the same
area as the currently proposed survey (RPS 2011).
Baird's Beaked Whale (Berardius bairdii)
Baird's beaked whale has a fairly extensive range across the North
Pacific north of 30[deg] N, and strandings have occurred as far north
as the Pribilof Islands (Rice 1986). Two forms of Baird's beaked whales
have been recognized--the common slate-gray form and a smaller, rare
black form (Morin et al. 2017). The gray form is seen off Japan, in the
Aleutians, and on the west coast of North America, whereas the black
from has been reported for northern Japan and the Aleutians (Morin et
al. 2017). Recent genetic studies suggest that the black form could be
a separate species (Morin et al. 2017).
Baird's beaked whale is currently divided into three distinct
stocks: Sea of Japan, Okhotsk Sea, and Bering Sea/eastern North Pacific
(Balcomb 1989; Reyes 1991). Baird's beaked whales sometimes are seen
close to shore, but their primary habitat is over or near the
continental slope and oceanic seamounts in waters 1,000-3,000 m deep
(Jefferson et al. 1993; Kasuya and Ohsumi 1984; Kasuya 2009).
Baird's beaked whale is migratory, arriving in the Bering Sea in
the spring, and remaining there throughout the summer; the winter
distribution is unknown (Kasuya 2002). There are numerous sighting
records from the central GOA to the Aleutian Islands and the southern
Bering Sea (Leatherwood et al. 1983; Kasuya and Ohsumi 1984; Forney and
Brownell 1996; Brueggeman et al. 1987; Moore et al. 2002b; Waite 2003;
Wade et al. 2003). There were seven sightings of Baird's beaked whales
(58 animals) during a 2013 survey in the U.S. Navy training area east
of Kodiak (Rone et al. 2017). Additionally, there were nine acoustic
encounters with Baird's beaked whales during the 2013 towed-hydrophone
survey in that study (Rone et al. 2014). There were also five sightings
(eight animals) of unidentified beaked whales during that survey. No
beaked whales were observed in 2009 or 2015 surveys in the same area
(Rone et al. 2017). Baird's beaked whales were detected acoustically
during fixed-PAM studies in this area during the 2011-2012 and 2012-
2013 studies but not in 2014-2015 (Baumann-Pickering et al. 2012;
Debich et al. 2013; Rice et al. 2015). They were detected regularly at
the slope site from November through and January and at the Pratt
Seamount site during most months. Beaked whales were not observed
during the L-DEO seismic survey conducted in the summer of 2011 in the
same area as the currently proposed survey (RPS 2011).
Pacific White-Sided Dolphin (Lagenorhynchus obliquidens)
The Pacific white-sided dolphin is found throughout the temperate
North Pacific, in a relatively narrow distribution between 38[deg] N
and 47[deg] N (Brownell et al. 1999). It is common both on the high
seas and along the continental margins (Leatherwood et al. 1984;
Dahlheim and Towell 1994; Ferrero and Walker 1996). Pacific white-sided
dolphins often associate with other species, including cetaceans
(especially Risso's and northern right whale dolphins; Green et al.
1993), pinnipeds, and seabirds.
Pacific white-sided dolphins were seen throughout the North Pacific
during surveys conducted during 1983-1990 (Buckland et al. 1993;
Miyashita 1993b). During winter, this species is most abundant in
California slope and offshore areas; as northern marine waters begin to
warm in the spring, it appears to move north to slope and
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offshore waters off Oregon/Washington (Green et al. 1992, 1993; Forney
1994; Forney et al. 1995; Buchanan et al. 2001; Barlow 2003). During
the summer, Pacific white-sided dolphins occur north into the GOA and
west to Amchitka in the Aleutian Islands, but rarely in the southern
Bering Sea (Allen and Angliss 2010). Moore et al. (2002b) documented a
single sighting of eight Pacific white-sided dolphins in the southeast
Bering Sea along the Alaska Peninsula. Sightings in the GOA and
Aleutian Islands have been documented in the summer by Waite (2003) and
Wade et al. (2003), and in the spring to the southeast of Kodiak Island
by Rone et al. (2010). Dahlheim and Towell (1994) reported sightings
for southeast Alaska. There was one sighting of 60 Pacific white-sided
dolphins in 2009, no sightings in 2013, and 10 sightings of Pacific
white-sided dolphins (986 animals) in 2015 during surveys in the U.S.
Navy training area east of Kodiak (Rone et al. 2017). Pacific white-
sided dolphins were not observed during the L-DEO seismic survey
conducted in the summer of 2011 in the same area as the currently
proposed survey (RPS 2011), but there was one sighting of two
unidentified small odontocetes.
Risso's Dolphin (Grampus griseus)
Risso's dolphin is primarily a tropical and mid-temperate species
distributed worldwide (Kruse et al. 1999). It occurs between 60[deg] N
and 60[deg] S, where surface water temperatures are at least 10[deg] C
(Kruse et al. 1999). Water temperature appears to be an important
factor affecting its distribution (Kruse et al. 1999). Although it
occurs from coastal to deep water, it shows a strong preference for
mid-temperate waters of the continental shelf and slope (Jefferson et
al. 2014).
Throughout the region from California to Washington, the
distribution and abundance of Risso's dolphins are highly variable,
presumably in response to changing oceanographic conditions on both
annual and seasonal time scales (Forney and Barlow 1998; Buchanan et
al. 2001; Becker 2007). Water temperature appears to be an important
factor affecting their distribution (Kruse et al. 1999; see also Becker
2007). Like the Pacific white-sided dolphin, Risso's dolphin is
believed to make seasonal north-south movements related to water
temperature, spending colder winter months off California and moving
north to waters off Oregon/Washington during the spring and summer as
northern waters begin to warm (Green et al. 1992, 1993; Buchanan et al.
2001; Barlow 2003; Becker 2007). Risso's dolphins are uncommon to rare
in the GOA. Risso's dolphins have been sighted near Chirikof Island
(southwest of Kodiak Island) and offshore in the GOA (Consiglieri et
al. 1980; Braham 1983). They were detected acoustically once, in
January 2013, near Pratt Seamount during fixed-PAM studies from 2011-
2015 in the U.S. Navy training area (Debich et al. 2013). The DoN
(2014) considers this species to be only an occasional visitor to their
GOA training area. Risso's dolphins were not observed during the L-DEO
seismic survey conducted in the summer of 2011 in the same area as the
currently proposed survey (RPS 2011). There was one sighting of two
unidentified small odontocetes.
Killer Whale (Orcinus orca)
The killer whale is cosmopolitan and globally fairly abundant; it
has been observed in all oceans of the World (Ford 2009). It is very
common in temperate waters and also frequents tropical waters, at least
seasonally (Heyning and Dahlheim 1988). High densities of the species
occur in high latitudes, especially in areas where prey is abundant.
Killer whale movements generally appear to follow the distribution of
their prey, which includes marine mammals, fish, and squid.
Of eight killer whale stocks currently recognized in the Pacific
U.S., six occur in Alaskan waters: (1) The Eastern North Pacific Alaska
Resident Stock, from southeast Alaska to the Aleutians and Bering Sea,
(2) the Eastern North Pacific Northern Resident Stock, from B.C.
through parts of southeast Alaska, (3) the Eastern North Pacific Gulf
of Alaska, Aleutian Islands, and Bering Sea Transient Stock, from PWS
through to the Aleutians and Bering Sea, (4) the AT1 Transient Stock,
from PWS through the Kenai Fjords, (5) the West Coast Transient Stock,
from California through southeast Alaska, and (6) the Offshore Stock,
from California through Alaska. The AT1 Transient Stock is considered
depleted under the MMPA and therefore a strategic stock. Movements of
resident groups between different geographic areas have also been
documented (Leatherwood et al. 1990; Dahlheim et al. 1997; Matkin et
al. 1997, 1999 in Allen and Angliss 2010). In the proposed study area,
individuals from one resident stock (Eastern North Pacific Alaska
Resident Stock), the North Pacific Offshore Stock, and one transient
stock (Eastern North Pacific Gulf of Alaska, Aleutian Islands, and
Bering Sea Transient Stock), could be encountered during the survey.
AT1 transients have only ever been seen in Prince William Sound and in
the Kenai Fjords region (Muto et al., 2018; Matkin et al 2008).
Therefore, while the stock is present in the Gulf of Alaska, the
limited range of the stock and the fact that this range does not
overlap with L-DEO's proposed survey means take is not likely to occur
for the AT1 stock of transient killer whales.
During surveys of the western GOA and Aleutian Islands, transient
killer whale densities were higher south of the Alaska Peninsula
between the Shumagin Islands and the eastern Aleutians than in other
areas (Wade et al. 2003; Zerbini et al. 2007). They were not seen
between the Shumagin Islands and the eastern side of Kodiak Island
during surveys in 2001-2003, but they were sighted there during earlier
surveys (e.g., Dahlheim 1997 in Zerbini et al. 2007). Resident killer
whales were most abundant near Kodiak Island, around Umnak and Unalaska
Islands in the eastern Aleutians, and in Seguam Pass in the central
Aleutians (Wade et al. 2003; Zerbini et al. 2007). No residents were
seen between 156[deg] W and 164[deg] W, south of the Alaska Peninsula
(Zerbini et al. 2007).
Little is known about offshore killer whales in the GOA, but they
could be encountered during the proposed survey. During summer surveys
of the western GOA and Aleutian Islands in 2001-2003, two sightings of
offshore killer whales were made, one northeast of Unalaska Island and
another one south of Kodiak Island near the Trinity Islands (Wade et
al. 2003; Zerbini et al. 2007). As the groups sighted were large, it
suggests the number of offshore killer whales in the area is relatively
high (Zerbini et al. 2007). Dahlheim et al. (2008b) encountered groups
of 20-60 killer whales in western Alaska; offshore killer whales
encountered near Kodiak Island and the eastern Aleutians were also
sighted in southeast Alaska and California. A group of at least 54
offshore killer whales was sighted in July 2003 during a survey in the
eastern Aleutian Islands (Matkin et al. 2007).
Rone et al. (2017) reported six killer whale sightings (119
animals) in 2009, 21 killer whale sightings (138 animals) in 2013, and
10 killer whale sightings (73 animals) in 2015 in the U.S. Navy
training area east of Kodiak. Additionally, there were 32 acoustic
encounters with killer whales and three acoustic encounters with
offshore killer whales (based on known differences in their acoustic
signals) during the 2013 towed-hydrophone survey in that study (Rone et
al. 2014). Killer whales were detected acoustically sporadiacally
throughout the year at shelf, slope, and seamount sites in the U.S.
Navy training area (Baumann-Pickering et al. 2012;
[[Page 14211]]
Debich et al. 2013). Rone et al. (2017) an abundance estimate
(uncorrected for missed animals) for the area of 899 killer whales,
most of which were found in slope waters. There was one sighting of a
single killer whale during the L-DEO seismic survey conducted in the
summer of 2011 in the same area as the currently proposed survey (RPS
2011).
Dall's Porpoise (Phocoenoides dalli)
Dall's porpoise is only found in the North Pacific and adjacent
seas. It is widely distributed across the North Pacific over the
continental shelf and slope waters, and over deep (>2,500 m) oceanic
waters (Hall 1979), ranging from ~30-62[deg] N (Jefferson et al. 2015).
In general, this species is common throughout its range (Buckland et
al. 1993). It is known to approach vessels to bowride (Jefferson 2009).
Dall's porpoise occurs throughout Alaska; the only apparent gaps in
distribution in Alaskan waters south of the Bering Strait are for upper
Cook Inlet and the Bering Sea shelf. Using a population estimate based
on vessel surveys during 1987-1991, and correcting for the tendency of
this species to approach vessels, which Turnock and Quinn (1991)
suggested resulted in inflated abundance estimates perhaps by as much
as five times, a population estimate of 83,400 was calculated for the
Alaska stock of Dall's porpoise. Because this estimate is more than
eight years old, NMFS considers it to be unreliable and reported that
there are no reliable abundance estimates available for the Alaska
Stock of this species when it was last reviewed (Muto et al. 2016).
Numerous studies have documented the occurrence of Dall's porpoise
in the Aleutian Islands and western GOA (Forney and Brownell 1996;
Moore 2001; Wade et al. 2003; Waite 2003; Baraff et al. 2005; Ireland
et al. 2005) as well as in the Bering Sea (Moore et al. 2002b). Dall's
porpoise was one of the most frequently sighted species during summer
seismic surveys in the central and eastern GOA and southeast Alaska
(MacLean and Koski 2005; Hauser and Holst 2009). Rone et al. (2017)
reported 10 Dall's porpoise sightings (59 animals) in 2009, 337 Dall's
porpoise sightings (907 animals) in 2013, and 98 Dall's porpoise
sightings (391 animals) in 2015 in the U.S. Navy training area east of
Kodiak. Additionally, there were three acoustic encounters with Dall's
porpoise during the 2013 towed-hydrophone survey in that study (Rone et
al. 2014). Rone et al. (2017) provided an abundance estimate for the
area of 15,423 Dall's porpoises. This estimate was uncorrected for
missed animals and did not account for their propensity to approach
vessels. Dall's porpoise was the second most frequently sighted
cetacean during the L-DEO seismic survey conducted in the summer of
2011 in the same area as the currently proposed survey, comprising 14.1
percent of all cetacean sightings (RPS 2011). There were 26 sightings
of this species, representing 227 animals during the 37 days of
monitoring. The average group size was nine and the largest group size
was 35.
Harbor Porpoise (Phocoena phocoena)
The harbor porpoise inhabits temperate, subarctic, and arctic
waters. It is typically found in shallow water (<100 m) nearshore but
is occasionally sighted in deeper offshore water (Jefferson et al.
2015); abundance declines linearly as depth increases (Barlow 1988). In
the eastern North Pacific, its range extends from Point Barrow, Alaska,
to Point Conception, California.
In Alaska, there are three separate stocks of harbor porpoise:
Southeast Alaska, GOA, and Bering Sea. The Southeast Alaska Stock
occurs from northern B.C. to Cape Suckling, and the GOA Stock ranges
from Cape Suckling to Unimak Pass. The population estimates for the
Southeast Alaska, GOA, and Bering Sea stocks are 11,146, 31,046, and
48,215, respectively (Muto et al. 2016). The Southeast Alaska stock is
Harbor porpoise are seen regularly in the western GOA and Aleutian
Islands (e.g., Wade et al. 2003; Waite 2003; Baraff et al. 2005;
Ireland et al. 2005) and Bering Sea (Moore et al. 2002b). Harbor
porpoises are also sighted in the eastern and central GOA and southeast
Alaska (Dahlheim et al. 2000, 2008a; MacLean and Koski 2005; Rone et
al. 2010). There were 30 sightings (89 animals) of harbor porpoise in
2009, eight sightings (11 animals) of harbor porposie in 2013, and a
single sighting of one harbor porpoise in 2015 during surveys in the
U.S. Navy training area east of Kodiak (Rone et al. 2017). Harbor
porpoise were not observed during the L-DEO seismic survey conducted in
the summer of 2011 in the same area as the currently proposed survey
(RPS 2011), but there was one sighting of two unidentified small
odontocetes.
Pinnipeds
Northern Fur Seal (Callorhinus ursinus)
The northern fur seal is endemic to the North Pacific Ocean and
occurs from southern California to the Bering Sea, Okhotsk Sea, and
Honshu Island, Japan (Muto et al. 2018). During the breeding season,
most of the worldwide population of northern fur seals inhabits the
Pribilof Islands in the southern Bering Sea (Lee et al. 2014; Muto et
al. 2018). The rest of the population occurs at rookeries on Bogoslof
Island in the Bering Sea, in Russia (Commander Islands, Robben Island,
Kuril Islands), on San Miguel Island in southern California (NMFS 1993;
Lee et al. 2014), and on the Farallon Islands off central California
(Muto et al. 2018). In the United States, two stocks are recognized--
the Eastern Pacific and the California stocks (Muto et al. 2018). The
Eastern Pacific stock ranges from the Pribilof Islands and Bogoslof
Island in the Bering Sea during summer to California during winter
(Muto et al. 2018).
When not on rookery islands, northern fur seals are primarily
pelagic but occasionally haul out on rocky shorelines (Muto et al.
2018). During the breeding season, adult males usually come ashore in
May-August and may sometimes be present until November; adult females
are found ashore from June-November (Carretta et al. 2017; Muto et al.
2018). After reproduction, northern fur seals spend the next 7-8 months
feeding at sea (Roppel 1984). Once weaned, juveniles spend 2-3 years at
sea before returning to rookeries. Animals may migrate to the GOA, off
Japan, and the west coast of the United States (Muto et al. 2018). Pups
travel through Aleutian passes and spend the first two years at sea
before returning to their islands of origin.
In November, adult females and pups leave the Pribilof Islands and
migrate into the North Pacific Ocean to areas including offshore Oregon
and Washington (Ream et al. 2005). Males usually migrate only as far
south as the GOA (Kajimura 1984). Ream et al. (2005) showed that
migrating females moved over the continental shelf as they migrated
southeasterly. Instead of following depth contours, their travel
corresponded with movements of the Alaska Gyre and the North Pacific
Current (Ream et al. 2005). Their foraging areas were associated with
eddies, the subarctic-subtropical transition region, and coastal mixing
(Ream et al. 2005; Alford et al. 2005). Some juveniles and non-pregnant
females may remain in the GOA throughout the summer (Calkins 1986).
Robson et al. (2004) reported that female fur seals from St. Paul
and St. George islands traveled in different directions. They also
observed habitat separation among breeding sites on the same island
(Robson et al. 2004). Lactating females from the same breeding site
share a foraging area,
[[Page 14212]]
whereas females from different sites tend to forage in different areas
(Robson et al. 2004). Females from both islands traveled for similar
durations and maximum distances (Robson et al. 2004).
Northern fur seals were seen throughout the North Pacific during
surveys conducted during 1987-1990 (Buckland et al. 1993). Tracked
adult male fur seals that were tagged on St. Paul Island in the Bering
Sea in October 2009, wintered in the Bering Sea or northern North
Pacific Ocean; females migrated to the GOA and the California Current
(Sterling et al. 2014).
A total of 42 northern fur seals was seen during 3767 km of
shipboard surveys in the northwestern GOA during June-July 1987
(Brueggeman et al. 1988). Leatherwood et al. (1983) reported 14
sightings of 34 northern fur seals away from the breeding islands in
the southeast Bering Sea during aerial surveys in 1982, mostly during
July and August. No fur seals were seen during summer surveys in the
GOA in 2004 and 2008 (MacLean and Koski 2005; Hauser and Holst 2009) or
during spring surveys in 2009 (Rone et al. 2010). None of the 42 female
northern fur seals tagged on St Paul Island between August-October 2007
and 2008 traveled south of the Aleutian Islands (Kuhn et al. 2010).
Rone et al. (2014) reported 78 northern fur seal sightings (83 animals)
in 2013 in the U.S. Navy training area east of Kodiak. They also
provided an abundance estimate (uncorrected for missed animals) for the
area of 1770 northern fur seals. There were seven sightings,
representing 7 northern fur seals, during the L-DEO seismic survey
conducted in the summer of 2011 in the same area as the currently
proposed survey (RPS 2011).
Steller Sea Lion (Eumetopias jubatus)
The Steller sea lion occurs along the North Pacific Rim from
northern Japan to California (Loughlin et al. 1984). They are
distributed around the coasts to the outer shelf from northern Japan
through the Kuril Islands and Okhotsk Sea, through the Aleutian
Islands, central Bering Sea, southern Alaska, and south to California
(NMFS 2016c). There are two stocks, or DPSs, of Steller sea lions--the
Western and Eastern DPSs, which are divided at 144[deg] W longitude
(NMFS 2016c). The Western DPS is listed as endangered and includes
animals that occur in Japan and Russia (NMFS 2016c; Muto et al. 2017);
the Eastern DPS was delisted from threatened in 2013 (NMFS 2013a).
Critical habitat has been designated 20 nmi around all major haulouts
and rookeries, as well as three large foraging areas (NMFS 2017b). The
critical habitat of both stocks is currently under review in light of
the delisting of the Eastern DPS (Muto et al. 2018). Critical habitat
as well as ``no approach'' zones occur within the proposed study area.
``No approach'' zones are restricted areas wherein no vessel may
approach within 3 nmi (5.6 km) of listed rookeries (50 CFR 223.202).
Only individuals from the Western DPS are expected to occur in the
proposed survey area. The Eastern DPS is estimated at 41,638 (Muto et
al. 2017) and appears to have increased at an annual rate of 4.76
percent between 1989 and 2015 (Muto et al. 2018).
Rookeries of Steller sea lions from the Western DPS are located on
the Aleutian Islands and along the Gulf of Alaska, as well as the east
coast of Kamchatka, Commander Islands, and Kuril Islands (Burkanov and
Loughlin 2005; Fritz et al. 2016; Muto et al. 2017). Breeding adults
occupy rookeries from late-May to early-July (NMFS 2008). Non-breeding
adults use haulouts or occupy sites at the periphery of rookeries
during the breeding season (NMFS 2008). Pupping occurs from mid-May to
mid July (Pitcher and Calkins 1981) and peaks in June (Pitcher et al.
2002). Territorial males fast and remain on land during the breeding
season (NMFS 2008). Females with pups generally stay within 30 km of
the rookeries in shallow (30-120 m) water when feeding (NMFS 2008).
Tagged juvenile sea lions showed localized movements near shore (Briggs
et al. 2005). Loughlin et al. (2003) reported that most (88 percent)
at-sea movements of juvenile Steller sea lions in the Aleutian Islands
were short (<15 km) foraging trips. The mean distance of juvenile sea
lion trips at sea was 16.6 km and the maximum trip distance recorded
was 447 km. Long-range trips represented 6 percent of all trips at sea,
and trip distance and duration increase with age (Loughlin et al. 2003;
Call et al. 2007). Although Steller sea lions are not considered
migratory, foraging animals can travel long distances outside of the
breeding season (Loughlin et al. 2003; Raum-Suryan et al. 2002).
Steller sea lions are present in Alaska year-round, with centers of
abundance in the GOA and Aleutian Islands. There are five major rookery
sites within the study area in the northern GOA: Chirikof, Chowiet,
Atkins, Chernabura islands, and Pinnacle Rock. There are also numerous
haulout sites located within the study area (see Figure 1 in the IHA
Application); most haulout sites on Kodiak Island (and within the study
area) are used year-round (e.g., Wynne 2005). Counts are highest in
late summer (Wynne 2005). Sea lion counts in the central GOA, including
Kodiak Island, were reported to be declining between 1999 and 2003
(Sease and Gudmundson 2002; Wynne 2005). Evidence suggests that counts
in Alaska were lowest in 2002 and 2003, but between 2003 and 2016 pup
and non-pup counts have increased by 2.19 percent per year and 2.24
percent per year, respectively (Muto et al. 2018). These rates vary
regionally, with the highest rates of increase in the eastern Gulf of
Alaska and a steadily decreasing rate of increase heading west to the
Aleutian Islands.
Steller sea lions 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. In 2008, 19 sea lions were taken in the Kodiak
Island region and 9 were taken along the South Alaska Peninsula (Wolfe
et al. 2009). As of 2009, data on community subsistence harvests are no
longer being collected consistently so no data are available. The most
recent 5 years of data available (2004-2008) show an annual average
catch of 172 steller sea lions for all areas in Alaska combined except
the Pribilof Islands in the Bering Sea (Muto et al. 2018).
There was one sighting of 18 Steller sea lions during the L-DEO
seismic survey conducted in the summer of 2011 in the same area as the
currently proposed survey (RPS 2011).
Northern Elephant Seal (Mirounga angustirostris)
Northern elephant seals breed in California and Baja California,
primarily on offshore islands (Stewart et al. 1994), from December-
March (Stewart and Huber 1993). Adult elephant seals engage in two long
northward migrations per year, one following the breeding season, and
another following the annual molt, with females returning earlier to
molt (March-April) than males (July-August) (Stewart and DeLong 1995).
Juvenile elephant seals typically leave the rookeries in April or May
and head north, traveling an average of 900-1,000 km. Hindell and
Perrin (2009) noted that traveling likely takes place in water depths
>200 m.
When not breeding, elephant seals feed at sea far from the
rookeries, ranging as far north as 60[deg] N, into the GOA and along
the Aleutian Islands (Le Boeuf et al. 2000). Some seals that were
tracked via satellite-tags for no more than 224 days traveled distances
in excess of 10,000 km during that time (Le Beouf et al. 2000).
Northern elephant
[[Page 14213]]
seals that were satellite-tagged at a California rookery have been
recorded traveling as far west as ~166.5-172.5[deg] E (Le Boeuf et al.
2000; Robinson et al. 2012; Robinson 2016 in OBIS 2018; Costa 2017 in
OBIS 2018). Post-molting seals traveled longer and farther than post-
breeding seals (Robinson et al. 2012). Rone et al. (2014) reported 16
northern fur seal sightings (16 animals) in a June-July 2013 survey in
the U.S. Navy training area east of Kodiak. Northern elephant seal
males could occur in the GOA throughout the year (Calkins 1986).
California Sea Lion (Zalophus californianus)
The primary range of the California sea lion includes the coastal
areas and offshore islands of the eastern North Pacific Ocean from BC,
Canada, to central Mexico, including the Gulf of California (Jefferson
et al. 2015). However, its distribution is expanding (Jefferson et al.
2015), and its secondary range extends into the GOA where it is
occasionally recorded (Maniscalco et al. 2004) and southern Mexico
(Gallo-Reynoso and Sol[oacute]rzano-Velasco 1991). California sea lions
are coastal animals that often haul out on shore throughout the year.
King (1983) noted that sea lions are rarely found more than 16 km
offshore. During fall and winter surveys off Oregon/Washington, mean
distance from shore was ~13 km (Bonnell et al. 1992).
California sea lion rookeries are on islands located in southern
California, western Baja California, and the Gulf of California
(Carretta et al. 2016). A single stock is recognized in U.S. waters:
The U.S. Stock. Five genetically distinct geographic populations have
been identified: (1) Pacific Temperate (includes rookeries in U.S.
waters and the Coronados Islands to the south), (2) Pacific
Subtropical, (3) Southern Gulf of California, (4) Central Gulf of
California, and (5) Northern Gulf of California (Schramm et al. 2009).
Animals from the Pacific Temperate population occur in the proposed
project area. California sea lions that are sighted in Alaska are
typically seen at Steller sea lion rookeries or haulouts, with most
sightings occurring between March and May, although they can be found
in the GOA year-round (Maniscalco et al. 2004).
Harbor Seal (Phoca vitulina)
The harbor seal is distributed in the North Atlantic and North
Pacific. Two subspecies occur in the Pacific: P.v. stejnegeri in the
northwest Pacific Ocean and P.v. richardii in the eastern Pacific
Ocean. Eastern Pacific harbor seals occur in nearshore, coastal, and
estuarine areas ranging from Baja California, Mexico, north to the
Pribilof Islands in Alaska (Muto et al. 2016). Harbor seals inhabit
estuarine and coastal waters, hauling out on rocks, reefs, beaches, and
glacial ice flows. They are generally non-migratory, but move locally
with the tides, weather, season, food availability, and reproduction
(Scheffer and Slipp 1944; Fisher 1952; Bigg 1969, 1981). Twelve stocks
of harbor seals are recognized in Alaska (Muto et al. 2016). The
proposed survey would take place within the range of three of these
stocks: North Kodiak, South Kodiak, and Cook Inlet/Shelikof Strait
stocks. Nearby stocks are the Aleutian Islands, Prince William Sound,
and Glacier Bay/Icy Strait stocks. There are two stocks in the Bering
Sea (Bristol Bay and Pribilof Islands) and four stocks in southeast
Alaska.
Female harbor seals give birth to a single pup while hauled out on
shore or on glacial ice flows; pups are born from May to mid-July. The
mother and pup remain together until weaning occurs at 3-6 weeks
(Bishop 1967; Bigg 1969). When molting, which occurs primarily in late
August, seals spend the majority of the time hauled out on shore,
glacial ice, or other substrates. Juvenile harbor seals can travel
significant distances (525 km) to forage or disperse, whereas adults
were generally found within 190 km of their tagging location in Prince
William Sound, Alaska (Lowry et al. 2001). The smaller home range used
by adults is suggestive of a strong site fidelity (Pitcher and Calkins
1979; Pitcher and McAllister 1981; Lowry et al. 2001). Pups tagged in
the GOA most commonly undertook multiple return trips of more than 75
km from natal areas, followed by movements of <25 km from the natal
area (Small et al. 2005). Pups tagged in Prince William Sound traveled
a mean maximum distance of 43.2 km from their tagging location, whereas
those tagged in the GOA moved a mean maximum distance of 86.6 km (Small
et al. 2005).
Harbor seals are an important subsistence resource for Alaska
Natives in the northern GOA. In 2011-2012, 37 harbor seals were taken
from the North Kodiak Stock and 126 harbor seals were taken from the
South Kodiak Stock by communities on Kodiak Island (Muto et al. 2016).
The number taken from the Cook Inlet/Shelikof Strait Stock for 2011-
2012 is unknown, but an average of 233 were taken from this stock
annually during 2004-2008 (Muto et al. 2016).
There was one sighting of nine harbor seals during the L-DEO
seismic survey conducted in the summer of 2011 in the same area as the
currently proposed survey (RPS 2011). Harbor seals could be encountered
in the proposed survey area.
Marine Mammal Hearing
Hearing is the most important sensory modality for marine mammals
underwater, and exposure to anthropogenic sound can have deleterious
effects. To appropriately assess the potential effects of exposure to
sound, it is necessary to understand the frequency ranges marine
mammals are able to hear. 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 whales).... 7 Hz to 35 kHz.
Mid-frequency (MF) cetaceans (dolphins, toothed 150 Hz to 160 kHz.
whales, beaked whales, bottlenose whales).
[[Page 14214]]
High-frequency (HF) cetaceans (true porpoises, 275 Hz to 160 kHz.
Kogia, river dolphins, cephalorhynchid,
Lagenorhynchus cruciger & L. australis).
Phocid pinnipeds (PW) (underwater) (true seals). 50 Hz to 86 kHz.
Otariid pinnipeds (OW) (underwater) (sea lions 60 Hz to 39 kHz.
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) have the reasonable potential to co-occur with
the proposed survey activities. Please refer to Table 1. Of the 16
cetacean species that may be present, 7 are classified as low-frequency
cetaceans (i.e., all mysticete species), 7 are classified as mid-
frequency cetaceans (i.e., all delphinid and ziphiid species and the
sperm whale), and 2 are classified as high-frequency cetaceans (i.e.,
harbor porpoise and Kogia spp.).
Potential Effects of Specified Activities on Marine Mammals and Their
Habitat
This section includes a summary and discussion of the ways that
components of the specified activity may impact marine mammals and
their habitat. The Estimated Take by Incidental Harassment section
later in this document includes a quantitative analysis of the number
of individuals that are expected to be taken by this activity. The
Negligible Impact Analysis and Determination section considers the
content of this section, the Estimated Take by Incidental Harassment
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.
Description of Active Acoustic Sound Sources
This section contains a brief technical background on sound, 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 a discussion of the potential effects of the specified
activity on marine mammals found later in this document.
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 (Hz) 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 dB. 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 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]Pa\2\-s)
represents the total energy contained within a pulse and considers both
intensity and duration of exposure. Peak sound pressure (also referred
to as zero-to-peak sound pressure or 0-p) 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.
Another common metric is peak-to-peak sound pressure (pk-pk), which is
the algebraic difference between the peak positive and peak negative
sound pressures. Peak-to-peak pressure is typically approximately 6 dB
higher than peak pressure (Southall et al., 2007).
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 pulses produced by the
airgun arrays 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. Ambient
sound is defined as environmental background sound levels lacking a
single source or point (Richardson et al., 1995), and 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 the following
(Richardson et al., 1995):
[[Page 14215]]
Wind and waves: The complex interactions between wind and
water surface, including processes such as breaking waves and wave-
induced bubble oscillations and cavitation, are a main source of
naturally occurring ambient sound for frequencies between 200 Hz and 50
kHz (Mitson, 1995). In general, ambient sound levels tend to increase
with increasing wind speed and wave height. Surf sound becomes
important near shore, with measurements collected at a distance of 8.5
km from shore showing an increase of 10 dB in the 100 to 700 Hz band
during heavy surf conditions;
Precipitation: Sound from rain and hail impacting the
water surface can become an important component of total sound at
frequencies above 500 Hz, and possibly down to 100 Hz during quiet
times;
Biological: 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; and
Anthropogenic: Sources of ambient sound related to human
activity include transportation (surface vessels), dredging and
construction, oil and gas drilling and production, seismic surveys,
sonar, explosions, and ocean acoustic studies. 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. Sound from identifiable anthropogenic sources other than the
activity of interest (e.g., a passing vessel) is sometimes termed
background sound, as opposed to ambient sound.
The sum of the various natural and anthropogenic sound sources at
any given location and time--which comprise ``ambient'' or
``background'' sound--depends not only on the source levels (as
determined by current 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 a given
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.
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 non-continuous (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 (such as
those used by the U.S. Navy). 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.
As described above, a Kongsberg EM 122 MBES, a Knudsen Chirp 3260
SBP, and a Teledyne RDI 75 kHz Ocean Surveyor ADCP would be operated
continuously during the proposed surveys, but not during transit to and
from the survey areas. Due to the lower source level of the Kongsberg
EM 122 MBES relative to the Langseth's airgun array (242 dB re 1 [mu]Pa
[middot] m for the MBES versus a minimum of 258 dB re 1 [mu]Pa [middot]
m (rms) for the 36 airgun array (NSF-USGS, 2011)), sounds from the MBES
are expected to be effectively subsumed by the sounds from the airgun
array. Thus, any marine mammal potentially exposed to sounds from the
MBES would already have been exposed to sounds from the airgun array,
which are expected to propagate further in the water. Each ping emitted
by the MBES consists of eight (in water >1,000 m deep) or four (<1,000
m) successive fan-shaped transmissions, each ensonifying a sector that
extends 1[deg] fore-aft. Given the movement and speed of the vessel,
the intermittent and narrow downward-directed nature of the sounds
emitted by the MBES would result in no more than one or two brief ping
exposures of any individual marine mammal, if any exposure were to
occur.
Due to the lower source levels of both the Knudsen Chirp 3260 SBP
and the Teledyne RDI 75 kHz Ocean Surveyor ADCP relative to the
Langseth's airgun array (maximum SL of 222 dB re 1 [mu]Pa [middot] m
for the SBP and maximum SL of 224 dB re 1 [mu]Pa [middot] m for the
ADCP, versus a minimum of 258 dB re 1 [mu]Pa [middot] m for the 36
airgun array (NSF-USGS, 2011)), sounds from the SBP and ADCP are
expected to be effectively subsumed by sounds from the airgun array.
Thus, any marine mammal potentially exposed to sounds from the SBP and/
or the ADCP would already have been exposed to sounds from the airgun
array, which are expected to propagate further in the water. As such,
we conclude that the likelihood of marine mammal take resulting from
exposure to sound from the MBES, SBP or ADCP (beyond that which is
already quantified as a result of exposure to the airguns) is
discountable and therefore we do not consider noise from the MBES, SBP
or ADCP further in this analysis.
Acoustic Effects
Here, we discuss the effects of active acoustic sources on marine
mammals.
Potential Effects of Underwater Sound--Please refer to the
information given previously (``Description of Active Acoustic
Sources'') regarding sound, characteristics of sound types, and
[[Page 14216]]
metrics used in this document. Anthropogenic sounds cover a broad range
of frequencies and sound levels and can have a range of highly variable
impacts on marine life, from none or minor to potentially severe
responses, depending on received levels, duration of exposure,
behavioral context, and various other factors. The potential effects of
underwater sound from active acoustic sources can potentially result in
one or more of the following: Temporary or permanent hearing
impairment, non-auditory physical or physiological effects, behavioral
disturbance, stress, and masking (Richardson et al., 1995; Gordon et
al., 2004; Nowacek et al., 2007; Southall et al., 2007; G[ouml]tz et
al., 2009). The degree of effect is intrinsically related to the signal
characteristics, received level, distance from the source, and duration
of the sound exposure. In general, sudden, high level sounds can cause
hearing loss, as can longer exposures to lower level sounds. Temporary
or permanent loss of hearing will occur almost exclusively for noise
within an animal's hearing range. We first describe specific
manifestations of acoustic effects before providing discussion specific
to the use of airgun arrays.
Richardson et al. (1995) described zones of increasing intensity of
effect that might be expected to occur, in relation to distance from a
source and assuming that the signal is within an animal's hearing
range. First is the area within which the acoustic signal would be
audible (potentially perceived) to the animal, but not strong enough to
elicit any overt behavioral or physiological response. The next zone
corresponds with the area where the signal is audible to the animal and
of sufficient intensity to elicit behavioral or physiological
responsiveness. Third is a zone within which, for signals of high
intensity, the received level is sufficient to potentially cause
discomfort or tissue damage to auditory or other systems. Overlaying
these zones to a certain extent is the area within which masking (i.e.,
when a sound interferes with or masks the ability of an animal to
detect a signal of interest that is above the absolute hearing
threshold) may occur; the masking zone may be highly variable in size.
We describe the more severe effects of certain non-auditory
physical or physiological effects only briefly as we do not expect that
use of airgun arrays are reasonably likely to result in such effects
(see below for further discussion). Potential effects from impulsive
sound sources can range in severity from effects such as behavioral
disturbance or tactile perception to physical discomfort, slight injury
of the internal organs and the auditory system, or mortality (Yelverton
et al., 1973). Non-auditory physiological effects or injuries that
theoretically might occur in marine mammals exposed to high level
underwater sound or as a secondary effect of extreme behavioral
reactions (e.g., change in dive profile as a result of an avoidance
reaction) caused by exposure to sound include neurological effects,
bubble formation, resonance effects, and other types of organ or tissue
damage (Cox et al., 2006; Southall et al., 2007; Zimmer and Tyack,
2007; Tal et al., 2015). The survey activities considered here do not
involve the use of devices such as explosives or mid-frequency tactical
sonar that are associated with these types of effects.
Threshold Shift--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). Repeated sound exposure that
leads to TTS could cause PTS. In severe cases of PTS, there can be
total or partial deafness, while in most cases the animal has an
impaired ability to hear sounds in specific frequency ranges (Kryter,
1985).
When PTS occurs, there is physical damage to the sound receptors in
the ear (i.e., tissue damage), whereas TTS represents primarily tissue
fatigue and is reversible (Southall et al., 2007). In addition, other
investigators have suggested that TTS is within the normal bounds of
physiological variability and tolerance and does not represent physical
injury (e.g., Ward, 1997). Therefore, NMFS does not consider TTS to
constitute auditory injury.
Relationships between TTS and PTS thresholds have not been studied
in marine mammals, and there is no PTS data for cetaceans but such
relationships are assumed to be similar to those in humans and other
terrestrial mammals. PTS typically occurs at exposure levels at least
several dBs above (a 40-dB threshold shift approximates PTS onset;
e.g., Kryter et al., 1966; Miller, 1974) that inducing mild TTS (a 6-dB
threshold shift approximates TTS onset; e.g., Southall et al. 2007).
Based on data from terrestrial mammals, a precautionary assumption is
that the PTS thresholds for impulse sounds (such as airgun pulses as
received close to the source) are at least 6 dB higher than the TTS
threshold on a peak-pressure basis and PTS cumulative sound exposure
level thresholds are 15 to 20 dB higher than TTS cumulative sound
exposure level thresholds (Southall et al., 2007). Given the higher
level of sound or longer exposure duration necessary to cause PTS as
compared with TTS, it is considerably less likely that PTS could occur.
For mid-frequency cetaceans in particular, potential protective
mechanisms may help limit onset of TTS or prevent onset of PTS. Such
mechanisms include dampening of hearing, auditory adaptation, or
behavioral amelioration (e.g., Nachtigall and Supin, 2013; Miller et
al., 2012; Finneran et al., 2015; Popov et al., 2016).
TTS is the mildest form of hearing impairment that can occur during
exposure to sound (Kryter, 1985). While experiencing TTS, the hearing
threshold rises, and a sound must be at a higher level in order to be
heard. In terrestrial and marine mammals, TTS can last from minutes or
hours to days (in cases of strong TTS). In many cases, hearing
sensitivity recovers rapidly after exposure to the sound ends. Few data
on sound levels and durations necessary to elicit mild TTS have been
obtained for marine mammals.
Marine mammal hearing plays a critical role in communication with
conspecifics, and interpretation of environmental cues for purposes
such as predator avoidance and prey capture. Depending on the degree
(elevation of threshold in dB), duration (i.e., recovery time), and
frequency range of TTS, and the context in which it is experienced, TTS
can have effects on marine mammals ranging from discountable to
serious. For example, a marine mammal may be able to readily compensate
for a brief, relatively small amount of TTS in a non-critical frequency
range that occurs during a time where ambient noise is lower and there
are not as many competing sounds present. Alternatively, a larger
amount and longer duration of TTS sustained during time when
communication is critical for successful mother/calf interactions could
have more serious impacts.
Finneran et al. (2015) measured hearing thresholds in three captive
bottlenose dolphins before and after exposure to ten pulses produced by
a seismic airgun in order to study TTS induced after exposure to
multiple pulses. Exposures began at relatively low levels and gradually
increased over a period of several months, with the highest exposures
at peak SPLs from 196 to 210 dB and cumulative (unweighted) SELs from
193-195 dB.
[[Page 14217]]
No substantial TTS was observed. In addition, behavioral reactions were
observed that indicated that animals can learn behaviors that
effectively mitigate noise exposures (although exposure patterns must
be learned, which is less likely in wild animals than for the captive
animals considered in this study). The authors note that the failure to
induce more significant auditory effects likely due to the intermittent
nature of exposure, the relatively low peak pressure produced by the
acoustic source, and the low-frequency energy in airgun pulses as
compared with the frequency range of best sensitivity for dolphins and
other mid-frequency cetaceans.
Currently, TTS data only exist for four species of cetaceans
(bottlenose dolphin, beluga whale, harbor porpoise, and Yangtze finless
porpoise) exposed to a limited number of sound sources (i.e., mostly
tones and octave-band noise) in laboratory settings (Finneran, 2015).
In general, harbor porpoises have a lower TTS onset than other measured
cetacean species (Finneran, 2015). Additionally, the existing marine
mammal TTS data come from a limited number of individuals within these
species. There are no data available on noise-induced hearing loss for
mysticetes.
Critical questions remain regarding the rate of TTS growth and
recovery after exposure to intermittent noise and the effects of single
and multiple pulses. Data at present are also insufficient to construct
generalized models for recovery and determine the time necessary to
treat subsequent exposures as independent events. More information is
needed on the relationship between auditory evoked potential and
behavioral measures of TTS for various stimuli. For summaries of data
on TTS in marine mammals or for further discussion of TTS onset
thresholds, please see Southall et al. (2007), Finneran and Jenkins
(2012), Finneran (2015), and NMFS (2016a).
Behavioral Effects--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 (e.g.,
Richardson et al., 1995; Wartzok et al., 2003; Southall et al., 2007;
Weilgart, 2007; Archer et al., 2010). Behavioral reactions can vary not
only among individuals but also within an individual, depending on
previous experience with a sound source, context, and numerous other
factors (Ellison et al., 2012), and can vary depending on
characteristics associated with the sound source (e.g., whether it is
moving or stationary, number of sources, distance from the source).
Please see Appendices B-C of Southall et al. (2007) for a review of
studies involving marine mammal behavioral responses to sound.
Habituation can occur when an animal's response to a stimulus wanes
with repeated exposure, usually in the absence of unpleasant associated
events (Wartzok et al., 2003). Animals are most likely to habituate to
sounds that are predictable and unvarying. It is important to note that
habituation is appropriately considered as a ``progressive reduction in
response to stimuli that are perceived as neither aversive nor
beneficial,'' rather than as, more generally, moderation in response to
human disturbance (Bejder et al., 2009). The opposite process is
sensitization, when an unpleasant experience leads to subsequent
responses, often in the form of avoidance, at a lower level of
exposure. As noted, behavioral state may affect the type of response.
For example, animals that are resting may show greater behavioral
change in response to disturbing sound levels than animals that are
highly motivated to remain in an area for feeding (Richardson et al.,
1995; NRC, 2003; Wartzok et al., 2003). Controlled experiments with
captive marine mammals have showed pronounced behavioral reactions,
including avoidance of loud sound sources (Ridgway et al., 1997).
Observed responses of wild marine mammals to loud pulsed sound sources
(typically seismic airguns or acoustic harassment devices) have been
varied but often consist of avoidance behavior or other behavioral
changes suggesting discomfort (Morton and Symonds, 2002; see also
Richardson et al., 1995; Nowacek et al., 2007). However, many
delphinids approach acoustic source vessels with no apparent discomfort
or obvious behavioral change (e.g., Barkaszi et al., 2012).
Available studies show wide variation in response to underwater
sound; therefore, it is difficult to predict specifically how any given
sound in a particular instance might affect marine mammals perceiving
the signal. If a marine mammal does react briefly to an underwater
sound by changing its behavior or moving a small distance, the impacts
of the change are unlikely to be significant to the individual, let
alone the stock or population. However, if a sound source displaces
marine mammals from an important feeding or breeding area for a
prolonged period, impacts on individuals and populations could be
significant (e.g., Lusseau and Bejder, 2007; Weilgart, 2007; NRC,
2005). However, there are broad categories of potential response, which
we describe in greater detail here, that include alteration of dive
behavior, alteration of foraging behavior, effects to breathing,
interference with or alteration of vocalization, avoidance, and flight.
Changes in dive behavior can vary widely, and may consist of
increased or decreased dive times and surface intervals as well as
changes in the rates of ascent and descent during a dive (e.g., Frankel
and Clark, 2000; Ng and Leung, 2003; Nowacek et al., 2004; Goldbogen et
al., 2013a, b). Variations in dive behavior may reflect interruptions
in biologically significant activities (e.g., foraging) or they may be
of little biological significance. The impact of an alteration to dive
behavior resulting from an acoustic exposure depends on what the animal
is doing at the time of the exposure and the type and magnitude of the
response.
Disruption of feeding behavior can be difficult to correlate with
anthropogenic sound exposure, so it is usually inferred by observed
displacement from known foraging areas, the appearance of secondary
indicators (e.g., bubble nets or sediment plumes), or changes in dive
behavior. As for other types of behavioral response, the frequency,
duration, and temporal pattern of signal presentation, as well as
differences in species sensitivity, are likely contributing factors to
differences in response in any given circumstance (e.g., Croll et al.,
2001; Nowacek et al.; 2004; Madsen et al., 2006; Yazvenko et al.,
2007). A determination of whether foraging disruptions incur fitness
consequences would require information on or estimates of the energetic
requirements of the affected individuals and the relationship between
prey availability, foraging effort and success, and the life history
stage of the animal.
Visual tracking, passive acoustic monitoring, and movement
recording tags were used to quantify sperm whale behavior prior to,
during, and following exposure to airgun arrays at received levels in
the range 140-160 dB at distances of 7-13 km, following a phase-in of
sound intensity and full array
[[Page 14218]]
exposures at 1-13 km (Madsen et al., 2006; Miller et al., 2009). Sperm
whales did not exhibit horizontal avoidance behavior at the surface.
However, foraging behavior may have been affected. The sperm whales
exhibited 19 percent less vocal (buzz) rate during full exposure
relative to post exposure, and the whale that was approached most
closely had an extended resting period and did not resume foraging
until the airguns had ceased firing. The remaining whales continued to
execute foraging dives throughout exposure; however, swimming movements
during foraging dives were 6 percent lower during exposure than control
periods (Miller et al., 2009). These data raise concerns that seismic
surveys may impact foraging behavior in sperm whales, although more
data are required to understand whether the differences were due to
exposure or natural variation in sperm whale behavior (Miller et al.,
2009).
Variations in respiration naturally vary with different behaviors
and alterations to breathing rate as a function of acoustic exposure
can be expected to co-occur with other behavioral reactions, such as a
flight response or an alteration in diving. However, respiration rates
in and of themselves may be representative of annoyance or an acute
stress response. Various studies have shown that respiration rates may
either be unaffected or could increase, depending on the species and
signal characteristics, again highlighting the importance in
understanding species differences in the tolerance of underwater noise
when determining the potential for impacts resulting from anthropogenic
sound exposure (e.g., Kastelein et al., 2001, 2005, 2006; Gailey et
al., 2007, 2016).
Marine mammals vocalize for different purposes and across multiple
modes, such as whistling, echolocation click production, calling, and
singing. Changes in vocalization behavior in response to anthropogenic
noise can occur for any of these modes and may result from a need to
compete with an increase in background noise or may reflect increased
vigilance or a startle response. For example, in the presence of
potentially masking signals, humpback whales and killer whales have
been observed to increase the length of their songs (Miller et al.,
2000; Fristrup et al., 2003; Foote et al., 2004), while right whales
have been observed to shift the frequency content of their calls upward
while reducing the rate of calling in areas of increased anthropogenic
noise (Parks et al., 2007). In some cases, animals may cease sound
production during production of aversive signals (Bowles et al., 1994).
Cerchio et al. (2014) used passive acoustic monitoring to document
the presence of singing humpback whales off the coast of northern
Angola and to opportunistically test for the effect of seismic survey
activity on the number of singing whales. Two recording units were
deployed between March and December 2008 in the offshore environment;
numbers of singers were counted every hour. Generalized Additive Mixed
Models were used to assess the effect of survey day (seasonality), hour
(diel variation), moon phase, and received levels of noise (measured
from a single pulse during each ten minute sampled period) on singer
number. The number of singers significantly decreased with increasing
received level of noise, suggesting that humpback whale breeding
activity was disrupted to some extent by the survey activity.
Castellote et al. (2012) reported acoustic and behavioral changes
by fin whales in response to shipping and airgun noise. Acoustic
features of fin whale song notes recorded in the Mediterranean Sea and
northeast Atlantic Ocean were compared for areas with different
shipping noise levels and traffic intensities and during a seismic
airgun survey. During the first 72 h of the survey, a steady decrease
in song received levels and bearings to singers indicated that whales
moved away from the acoustic source and out of the study area. This
displacement persisted for a time period well beyond the 10-day
duration of seismic airgun activity, providing evidence that fin whales
may avoid an area for an extended period in the presence of increased
noise. The authors hypothesize that fin whale acoustic communication is
modified to compensate for increased background noise and that a
sensitization process may play a role in the observed temporary
displacement.
Seismic pulses at average received levels of 131 dB re 1 [mu]Pa\2\-
s caused blue whales to increase call production (Di Iorio and Clark,
2010). In contrast, McDonald et al. (1995) tracked a blue whale with
seafloor seismometers and reported that it stopped vocalizing and
changed its travel direction at a range of 10 km from the acoustic
source vessel (estimated received level 143 dB pk-pk). Blackwell et al.
(2013) found that bowhead whale call rates dropped significantly at
onset of airgun use at sites with a median distance of 41-45 km from
the survey. Blackwell et al. (2015) expanded this analysis to show that
whales actually increased calling rates as soon as airgun signals were
detectable before ultimately decreasing calling rates at higher
received levels (i.e., 10-minute SELcum of ~127 dB).
Overall, these results suggest that bowhead whales may adjust their
vocal output in an effort to compensate for noise before ceasing
vocalization effort and ultimately deflecting from the acoustic source
(Blackwell et al., 2013, 2015). These studies demonstrate that even low
levels of noise received far from the source can induce changes in
vocalization and/or behavior for mysticetes.
Avoidance is the displacement of an individual from an area or
migration path as a result of the presence of a sound or other
stressors, and is one of the most obvious manifestations of disturbance
in marine mammals (Richardson et al., 1995). For example, gray whales
are known to change direction--deflecting from customary migratory
paths--in order to avoid noise from seismic surveys (Malme et al.,
1984). Humpback whales showed avoidance behavior in the presence of an
active seismic array during observational studies and controlled
exposure experiments in western Australia (McCauley et al., 2000).
Avoidance may be short-term, with animals returning to the area once
the noise has ceased (e.g., Bowles et al., 1994; Goold, 1996; Stone et
al., 2000; Morton and Symonds, 2002; Gailey et al., 2007). Longer-term
displacement is possible, however, which may lead to changes in
abundance or distribution patterns of the affected species in the
affected region if habituation to the presence of the sound does not
occur (e.g., Bejder et al., 2006; Teilmann et al., 2006).
A flight response is a dramatic change in normal movement to a
directed and rapid movement away from the perceived location of a sound
source. The flight response differs from other avoidance responses in
the intensity of the response (e.g., directed movement, rate of
travel). Relatively little information on flight responses of marine
mammals to anthropogenic signals exist, although observations of flight
responses to the presence of predators have occurred (Connor and
Heithaus, 1996). The result of a flight response could range from
brief, temporary exertion and displacement from the area where the
signal provokes flight to, in extreme cases, marine mammal strandings
(Evans and England, 2001). However, it should be noted that response to
a perceived predator does not necessarily invoke flight (Ford and
Reeves, 2008), and whether individuals are solitary or in groups may
influence the response.
[[Page 14219]]
Behavioral disturbance can also impact marine mammals in more
subtle ways. Increased vigilance may result in costs related to
diversion of focus and attention (i.e., when a response consists of
increased vigilance, it may come at the cost of decreased attention to
other critical behaviors such as foraging or resting). These effects
have generally not been demonstrated for marine mammals, but studies
involving fish and terrestrial animals have shown that increased
vigilance may substantially reduce feeding rates (e.g., Beauchamp and
Livoreil, 1997; Fritz et al., 2002; Purser and Radford, 2011). In
addition, chronic disturbance can cause population declines through
reduction of fitness (e.g., decline in body condition) and subsequent
reduction in reproductive success, survival, or both (e.g., Harrington
and Veitch, 1992; Daan et al., 1996; Bradshaw et al., 1998). However,
Ridgway et al. (2006) reported that increased vigilance in bottlenose
dolphins exposed to sound over a five-day period did not cause any
sleep deprivation or stress effects.
Many animals perform vital functions, such as feeding, resting,
traveling, and socializing, on a diel cycle (24-hour cycle). Disruption
of such functions resulting from reactions to stressors such as sound
exposure are more likely to be significant if they last more than one
diel cycle or recur on subsequent days (Southall et al., 2007).
Consequently, a behavioral response lasting less than one day and not
recurring on subsequent days is not considered particularly severe
unless it could directly affect reproduction or survival (Southall et
al., 2007). Note that there is a difference between multi-day
substantive behavioral reactions and multi-day anthropogenic
activities. For example, just because an activity lasts for multiple
days does not necessarily mean that individual animals are either
exposed to activity-related stressors for multiple days or, further,
exposed in a manner resulting in sustained multi-day substantive
behavioral responses.
Stone (2015) reported data from at-sea observations during 1,196
seismic surveys from 1994 to 2010. When large arrays of airguns
(considered to be 500 in\3\ or more) were firing, lateral displacement,
more localized avoidance, or other changes in behavior were evident for
most odontocetes. However, significant responses to large arrays were
found only for the minke whale and fin whale. Behavioral responses
observed included changes in swimming or surfacing behavior, with
indications that cetaceans remained near the water surface at these
times. Cetaceans were recorded as feeding less often when large arrays
were active. Behavioral observations of gray whales during a seismic
survey monitored whale movements and respirations pre-, during and
post-seismic survey (Gailey et al., 2016). Behavioral state and water
depth were the best `natural' predictors of whale movements and
respiration and, after considering natural variation, none of the
response variables were significantly associated with seismic survey or
vessel sounds.
Stress Responses--An animal's perception of a threat may be
sufficient to trigger stress responses consisting of some combination
of behavioral responses, autonomic nervous system responses,
neuroendocrine responses, or immune responses (e.g., Seyle, 1950;
Moberg, 2000). In many cases, an animal's first and sometimes most
economical (in terms of energetic costs) response is behavioral
avoidance of the potential stressor. Autonomic nervous system responses
to stress typically involve changes in heart rate, blood pressure, and
gastrointestinal activity. These responses have a relatively short
duration and may or may not have a significant long-term effect on an
animal's fitness.
Neuroendocrine stress responses often involve the hypothalamus-
pituitary-adrenal system. Virtually all neuroendocrine functions that
are affected by stress--including immune competence, reproduction,
metabolism, and behavior--are regulated by pituitary hormones. Stress-
induced changes in the secretion of pituitary hormones have been
implicated in failed reproduction, altered metabolism, reduced immune
competence, and behavioral disturbance (e.g., Moberg, 1987; Blecha,
2000). Increases in the circulation of glucocorticoids are also equated
with stress (Romano et al., 2004).
The primary distinction between stress (which is adaptive and does
not normally place an animal at risk) and ``distress'' is the cost of
the response. During a stress response, an animal uses glycogen stores
that can be quickly replenished once the stress is alleviated. In such
circumstances, the cost of the stress response would not pose serious
fitness consequences. However, when an animal does not have sufficient
energy reserves to satisfy the energetic costs of a stress response,
energy resources must be diverted from other functions. This state of
distress will last until the animal replenishes its energetic reserves
sufficiently to restore normal function.
Relationships between these physiological mechanisms, animal
behavior, and the costs of stress responses are well-studied through
controlled experiments and for both laboratory and free-ranging animals
(e.g., Holberton et al., 1996; Hood et al., 1998; Jessop et al., 2003;
Krausman et al., 2004; Lankford et al., 2005). Stress responses due to
exposure to anthropogenic sounds or other stressors and their effects
on marine mammals have also been reviewed (Fair and Becker, 2000;
Romano et al., 2002b) and, more rarely, studied in wild populations
(e.g., Romano et al., 2002a). For example, Rolland et al. (2012) found
that noise reduction from reduced ship traffic in the Bay of Fundy was
associated with decreased stress in North Atlantic right whales. These
and other studies lead to a reasonable expectation that some marine
mammals will experience physiological stress responses upon exposure to
acoustic stressors and that it is possible that some of these would be
classified as ``distress.'' In addition, any animal experiencing TTS
would likely also experience stress responses (NRC, 2003).
Auditory Masking--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) (Richardson et al., 1995; Erbe et al.,
2016). 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. The ability of a noise
source to mask biologically important sounds depends on the
characteristics of both the noise source and the signal of interest
(e.g., signal-to-noise ratio, temporal variability, direction), in
relation to each other and to an animal's hearing abilities (e.g.,
sensitivity, frequency range, critical ratios, frequency
discrimination, directional discrimination, age or TTS hearing loss),
and existing ambient noise and propagation conditions.
Under certain circumstances, marine mammals experiencing
significant masking could also be impaired from maximizing their
performance fitness in survival and reproduction. Therefore, when the
coincident (masking) sound is man-made, it may be considered harassment
when disrupting or altering critical behaviors. It is important to
distinguish TTS and PTS, which persist after the sound exposure, from
masking,
[[Page 14220]]
which occurs during the sound exposure. Because masking (without
resulting in TS) is not associated with abnormal physiological
function, it is not considered a physiological effect, but rather a
potential behavioral effect.
The frequency range of the potentially masking sound is important
in determining any potential behavioral impacts. For example, low-
frequency signals may have less effect on high-frequency echolocation
sounds produced by odontocetes but are more likely to affect detection
of mysticete communication calls and other potentially important
natural sounds such as those produced by surf and some prey species.
The masking of communication signals by anthropogenic noise may be
considered as a reduction in the communication space of animals (e.g.,
Clark et al., 2009) and may result in energetic or other costs as
animals change their vocalization behavior (e.g., Miller et al., 2000;
Foote et al., 2004; Parks et al., 2007; Di Iorio and Clark, 2009; Holt
et al., 2009). Masking can be reduced in situations where the signal
and noise come from different directions (Richardson et al., 1995),
through amplitude modulation of the signal, or through other
compensatory behaviors (Houser and Moore, 2014). Masking can be tested
directly in captive species (e.g., Erbe, 2008), but in wild populations
it must be either modeled or inferred from evidence of masking
compensation. There are few studies addressing real-world masking
sounds likely to be experienced by marine mammals in the wild (e.g.,
Branstetter et al., 2013).
Masking affects both senders and receivers of acoustic signals and
can potentially have long-term chronic effects on marine mammals at the
population level as well as at the individual level. Low-frequency
ambient sound levels have increased by as much as 20 dB (more than
three times in terms of SPL) in the world's ocean from pre-industrial
periods, with most of the increase from distant commercial shipping
(Hildebrand, 2009). All anthropogenic sound sources, but especially
chronic and lower-frequency signals (e.g., from vessel traffic),
contribute to elevated ambient sound levels, thus intensifying masking.
Masking effects of pulsed sounds (even from large arrays of
airguns) on marine mammal calls and other natural sounds are expected
to be limited, although there are few specific data on this. Because of
the intermittent nature and low duty cycle of seismic pulses, animals
can emit and receive sounds in the relatively quiet intervals between
pulses. However, in exceptional situations, reverberation occurs for
much or all of the interval between pulses (e.g., Simard et al. 2005;
Clark and Gagnon 2006), which could mask calls. Situations with
prolonged strong reverberation are infrequent. However, it is common
for reverberation to cause some lesser degree of elevation of the
background level between airgun pulses (e.g., Gedamke 2011; Guerra et
al. 2011, 2016; Klinck et al. 2012; Guan et al. 2015), and this weaker
reverberation presumably reduces the detection range of calls and other
natural sounds to some degree. Guerra et al. (2016) reported that
ambient noise levels between seismic pulses were elevated as a result
of reverberation at ranges of 50 km from the seismic source. Based on
measurements in deep water of the Southern Ocean, Gedamke (2011)
estimated that the slight elevation of background levels during
intervals between pulses reduced blue and fin whale communication space
by as much as 36-51 percent when a seismic survey was operating 450-
2,800 km away. Based on preliminary modeling, Wittekind et al. (2016)
reported that airgun sounds could reduce the communication range of
blue and fin whales 2000 km from the seismic source. Nieukirk et al.
(2012) and Blackwell et al. (2013) noted the potential for masking
effects from seismic surveys on large whales.
Some baleen and toothed whales are known to continue calling in the
presence of seismic pulses, and their calls usually can be heard
between the pulses (e.g., Nieukirk et al. 2012; Thode et al. 2012;
Br[ouml]ker et al. 2013; Sciacca et al. 2016). As noted above, Cerchio
et al. (2014) suggested that the breeding display of humpback whales
off Angola could be disrupted by seismic sounds, as singing activity
declined with increasing received levels. In addition, some cetaceans
are known to change their calling rates, shift their peak frequencies,
or otherwise modify their vocal behavior in response to airgun sounds
(e.g., Di Iorio and Clark 2010; Castellote et al. 2012; Blackwell et
al. 2013, 2015). The hearing systems of baleen whales are undoubtedly
more sensitive to low-frequency sounds than are the ears of the small
odontocetes that have been studied directly (e.g., MacGillivray et al.
2014). The sounds important to small odontocetes are predominantly at
much higher frequencies than are the dominant components of airgun
sounds, thus limiting the potential for masking. In general, masking
effects of seismic pulses are expected to be minor, given the normally
intermittent nature of seismic pulses.
Ship Noise
Vessel noise from the Langseth could affect marine animals in the
proposed survey areas. Houghton et al. (2015) proposed that vessel
speed is the most important predictor of received noise levels, and
Putland et al. (2017) also reported reduced sound levels with decreased
vessel speed. Sounds produced by large vessels generally dominate
ambient noise at frequencies from 20 to 300 Hz (Richardson et al.
1995). However, some energy is also produced at higher frequencies
(Hermannsen et al. 2014); low levels of high-frequency sound from
vessels has been shown to elicit responses in harbor porpoise (Dyndo et
al. 2015). Increased levels of ship noise have been shown to affect
foraging by porpoise (Teilmann et al. 2015; Wisniewska et al. 2018);
Wisniewska et al. (2018) suggest that a decrease in foraging success
could have long-term fitness consequences.
Ship noise, through masking, can reduce the effective communication
distance of a marine mammal if the frequency of the sound source is
close to that used by the animal, and if the sound is present for a
significant fraction of time (e.g., Richardson et al. 1995; Clark et
al. 2009; Jensen et al. 2009; Gervaise et al. 2012; Hatch et al. 2012;
Rice et al. 2014; Dunlop 2015; Erbe et al. 2015; Jones et al. 2017;
Putland et al. 2017). In addition to the frequency and duration of the
masking sound, the strength, temporal pattern, and location of the
introduced sound also play a role in the extent of the masking
(Branstetter et al. 2013, 2016; Finneran and Branstetter 2013; Sills et
al. 2017). Branstetter et al. (2013) reported that time-domain metrics
are also important in describing and predicting masking. In order to
compensate for increased ambient noise, some cetaceans are known to
increase the source levels of their calls in the presence of elevated
noise levels from shipping, shift their peak frequencies, or otherwise
change their vocal behavior (e.g., Parks et al. 2011, 2012, 2016a,b;
Castellote et al. 2012; Melc[oacute]n et al. 2012; Azzara et al. 2013;
Tyack and Janik 2013; Lu[iacute]s et al. 2014; Sairanen 2014; Papale et
al. 2015; Bittencourt et al. 2016; Dahlheim and Castellote 2016;
Gospi[cacute] and Picciulin 2016; Gridley et al. 2016; Heiler et al.
2016; Martins et al. 2016; O'Brien et al. 2016; Tenessen and Parks
2016). Harp seals did not increase their call frequencies in
environments with increased low-frequency sounds (Terhune and Bosker
2016). Holt et al. (2015) reported that changes in vocal
[[Page 14221]]
modifications can have increased energetic costs for individual marine
mammals. A negative correlation between the presence of some cetacean
species and the number of vessels in an area has been demonstrated by
several studies (e.g., Campana et al. 2015; Culloch et al. 2016).
Baleen whales are thought to be more sensitive to sound at these
low frequencies than are toothed whales (e.g., MacGillivray et al.
2014), possibly causing localized avoidance of the proposed survey area
during seismic operations. Reactions of gray and humpback whales to
vessels have been studied, and there is limited information available
about the reactions of right whales and rorquals (fin, blue, and minke
whales). Reactions of humpback whales to boats are variable, ranging
from approach to avoidance (Payne 1978; Salden 1993). Baker et al.
(1982, 1983) and Baker and Herman (1989) found humpbacks often move
away when vessels are within several kilometers. Humpbacks seem less
likely to react overtly when actively feeding than when resting or
engaged in other activities (Krieger and Wing 1984, 1986). Increased
levels of ship noise have been shown to affect foraging by humpback
whales (Blair et al. 2016). Fin whale sightings in the western
Mediterranean were negatively correlated with the number of vessels in
the area (Campana et al. 2015). Minke whales and gray seals have shown
slight displacement in response to construction-related vessel traffic
(Anderwald et al. 2013).
Many odontocetes show considerable tolerance of vessel traffic,
although they sometimes react at long distances if confined by ice or
shallow water, if previously harassed by vessels, or have had little or
no recent exposure to ships (Richardson et al. 1995). Dolphins of many
species tolerate and sometimes approach vessels (e.g., Anderwald et al.
2013). Some dolphin species approach moving vessels to ride the bow or
stern waves (Williams et al. 1992). Pirotta et al. (2015) noted that
the physical presence of vessels, not just ship noise, disturbed the
foraging activity of bottlenose dolphins. Sightings of striped dolphin,
Risso's dolphin, sperm whale, and Cuvier's beaked whale in the western
Mediterranean were negatively correlated with the number of vessels in
the area (Campana et al. 2015).
There are few data on the behavioral reactions of beaked whales to
vessel noise, though they seem to avoid approaching vessels (e.g.,
W[uuml]rsig et al. 1998) or dive for an extended period when approached
by a vessel (e.g., Kasuya 1986). Based on a single observation, Aguilar
Soto et al. (2006) suggest foraging efficiency of Cuvier's beaked
whales may be reduced by close approach of vessels.
In summary, project vessel sounds would not be at levels expected
to cause anything more than possible localized and temporary behavioral
changes in marine mammals, and would not be expected to result in
significant negative effects on individuals or at the population level.
In addition, in all oceans of the world, large vessel traffic is
currently so prevalent that it is commonly considered a usual source of
ambient sound (NSF-USGS 2011).
Ship Strike
Vessel collisions with marine mammals, or ship strikes, can result
in death or serious injury of the animal. Wounds resulting from ship
strike may include massive trauma, hemorrhaging, broken bones, or
propeller lacerations (Knowlton and Kraus, 2001). An animal at the
surface may be struck directly by a vessel, a surfacing animal may hit
the bottom of a vessel, or an animal just below the surface may be cut
by a vessel's propeller. Superficial strikes may not kill or result in
the death of the animal. These interactions are typically associated
with large whales (e.g., fin whales), which are occasionally found
draped across the bulbous bow of large commercial ships upon arrival in
port. Although smaller cetaceans are more maneuverable in relation to
large vessels than are large whales, they may also be susceptible to
strike. 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).
Pace and Silber (2005) also found that the probability of death or
serious injury increased rapidly with increasing vessel speed.
Specifically, the predicted probability of serious injury or death
increased from 45 to 75 percent as vessel speed increased from 10 to 14
kn, and exceeded 90 percent at 17 kn. Higher speeds during collisions
result in greater force of impact, but higher speeds also appear to
increase the chance of severe injuries or death through increased
likelihood of collision by pulling whales toward the vessel (Clyne,
1999; Knowlton et al., 1995). In a separate study, Vanderlaan and
Taggart (2007) analyzed the probability of lethal mortality of large
whales at a given speed, showing that the greatest rate of change in
the probability of a lethal injury to a large whale as a function of
vessel speed occurs between 8.6 and 15 kn. 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, while the probability asymptotically
increases toward one hundred percent above 15 kn.
The Langseth travels at a speed of 5 kn (approximately 9.3 km/h)
while towing seismic survey gear (LGL 2018). At this speed, both the
possibility of striking a marine mammal and the possibility of a strike
resulting in serious injury or mortality are discountable. At average
transit speed, the probability of serious injury or mortality resulting
from a strike is less than 50 percent. However, the likelihood of a
strike actually happening is again discountable. Ship strikes, as
analyzed in the studies cited above, generally involve commercial
shipping, which is much more common in both space and time than is
geophysical survey activity. 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). No such incidents were reported for geophysical
survey vessels during that time period.
It is possible for ship strikes to occur while traveling at slow
speeds. For example, a hydrographic survey vessel traveling at low
speed (5.5 kn) while conducting mapping surveys off the central
California coast struck and killed a blue whale in 2009. The State of
California determined that the whale had suddenly and unexpectedly
surfaced beneath the hull, with the result that the propeller severed
the whale's vertebrae, and that this was an unavoidable event. This
strike represents the only such incident in approximately 540,000 hours
of similar coastal mapping activity (p = 1.9 x 10-\6\; 95
percent CI = 0-5.5 x 10-\6\; NMFS, 2013b). In addition, a
research vessel reported a fatal strike in 2011 of a dolphin in the
Atlantic, demonstrating that it is possible for strikes involving
smaller cetaceans to occur. In that case, the incident report indicated
that an animal apparently was struck by the vessel's propeller as it
was intentionally swimming near the vessel. While indicative of the
type of unusual events that cannot be ruled out, neither of these
instances represents a circumstance that would be considered reasonably
foreseeable or that would be considered preventable.
[[Page 14222]]
Although the likelihood of the vessel striking a marine mammal is
low, we require a robust ship strike avoidance protocol (see Proposed
Mitigation), which we believe eliminates any foreseeable risk of ship
strike. We anticipate that vessel collisions involving a seismic data
acquisition vessel towing gear, while not impossible, represent
unlikely, unpredictable events for which there are no preventive
measures. Given the required mitigation measures, the relatively slow
speed of the vessel towing gear, the presence of bridge crew watching
for obstacles at all times (including marine mammals), and the presence
of marine mammal observers, 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, and this potential effect of the specified activity will
not be discussed further in the following analysis.
Stranding--When a living or dead marine mammal swims or floats onto
shore and becomes ``beached'' or incapable of returning to sea, the
event is a ``stranding'' (Geraci et al., 1999; Perrin and Geraci, 2002;
Geraci and Lounsbury, 2005; NMFS, 2007). The legal definition for a
stranding under the MMPA is that (A) a marine mammal is dead and is (i)
on a beach or shore of the United States; or (ii) in waters under the
jurisdiction of the United States (including any navigable waters); or
(B) a marine mammal is alive and is (i) on a beach or shore of the
United States and is unable to return to the water; (ii) on a beach or
shore of the United States and, although able to return to the water,
is in need of apparent medical attention; or (iii) in the waters under
the jurisdiction of the United States (including any navigable waters),
but is unable to return to its natural habitat under its own power or
without assistance.
Marine mammals strand for a variety of reasons, such as infectious
agents, biotoxicosis, starvation, fishery interaction, ship strike,
unusual oceanographic or weather events, sound exposure, or
combinations of these stressors sustained concurrently or in series.
However, the cause or causes of most strandings are unknown (Geraci et
al., 1976; Eaton, 1979; Odell et al., 1980; Best, 1982). Numerous
studies suggest that the physiology, behavior, habitat relationships,
age, or condition of cetaceans may cause them to strand or might pre-
dispose them to strand when exposed to another phenomenon. These
suggestions are consistent with the conclusions of numerous other
studies that have demonstrated that combinations of dissimilar
stressors commonly combine to kill an animal or dramatically reduce its
fitness, even though one exposure without the other does not produce
the same result (Chroussos, 2000; Creel, 2005; DeVries et al., 2003;
Fair and Becker, 2000; Foley et al., 2001; Moberg, 2000; Relyea, 2005a;
2005b, Romero, 2004; Sih et al., 2004).
Use of military tactical sonar has been implicated in a majority of
investigated stranding events. Most known stranding events have
involved beaked whales, though a small number have involved deep-diving
delphinids or sperm whales (e.g., Mazzariol et al., 2010; Southall et
al., 2013). In general, long duration (~1 second) and high-intensity
sounds (>235 dB SPL) have been implicated in stranding events
(Hildebrand, 2004). With regard to beaked whales, mid-frequency sound
is typically implicated (when causation can be determined) (Hildebrand,
2004). Although seismic airguns create predominantly low-frequency
energy, the signal does include a mid-frequency component. We have
considered the potential for the proposed surveys to result in marine
mammal stranding and have concluded that, based on the best available
information, stranding is not expected to occur.
Effects to Prey--Marine mammal prey varies by species, season, and
location and, for some, is not well documented. Fish react to sounds
which are especially strong and/or intermittent low-frequency sounds.
Short duration, sharp sounds can cause overt or subtle changes in fish
behavior and local distribution. Hastings and Popper (2005) identified
several studies that suggest fish may relocate to avoid certain areas
of sound energy. Additional studies have documented effects of pulsed
sound on fish, although several are based on studies in support of
construction projects (e.g., Scholik and Yan, 2001, 2002; Popper and
Hastings, 2009). Sound pulses at received levels of 160 dB may cause
subtle changes in fish behavior. SPLs of 180 dB may cause noticeable
changes in behavior (Pearson et al., 1992; Skalski et al., 1992). SPLs
of sufficient strength have been known to cause injury to fish and fish
mortality. The most likely impact to fish from survey activities at the
project area would be temporary avoidance of the area. 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
anticipated.
Information on seismic airgun impacts to zooplankton, which
represent an important prey type for mysticetes, is limited. However,
McCauley et al. (2017) reported that experimental exposure to a pulse
from a 150 inch\3\ airgun decreased zooplankton abundance when compared
with controls, as measured by sonar and net tows, and caused a two- to
threefold increase in dead adult and larval zooplankton. Although no
adult krill were present, the study found that all larval krill were
killed after air gun passage. Impacts were observed out to the maximum
1.2 km range sampled.
In general, impacts to marine mammal prey are expected to be
limited due to the relatively small temporal and spatial overlap
between the proposed survey and any areas used by marine mammal prey
species. The proposed use of airguns as part of an active seismic array
survey would occur over a relatively short time period (~18 days) and
would occur over a very small area relative to the area available as
marine mammal habitat in the Gulf of Alaska. We believe any impacts to
marine mammals due to adverse affects to their prey would be
insignificant due to the limited spatial and temporal impact of the
proposed survey. However, adverse impacts may occur to a few species of
fish and to zooplankton.
Acoustic Habitat--Acoustic habitat is the soundscape--which
encompasses all of the sound present in a particular location and time,
as a whole--when considered from the perspective of the animals
experiencing it. Animals produce sound for, or listen for sounds
produced by, conspecifics (communication during feeding, mating, and
other social activities), other animals (finding prey or avoiding
predators), and the physical environment (finding suitable habitats,
navigating). Together, sounds made by animals and the geophysical
environment (e.g., produced by earthquakes, lightning, wind, rain,
waves) make up the natural contributions to the total acoustics of a
place. These acoustic conditions, termed acoustic habitat, are one
attribute of an animal's total habitat.
Soundscapes are also defined by, and acoustic habitat influenced
by, the total contribution of anthropogenic sound. This may include
incidental emissions from sources such as vessel traffic, or may be
intentionally introduced to the marine environment for data acquisition
purposes (as in the use of airgun arrays). Anthropogenic noise varies
widely in its frequency content, duration, and loudness and these
characteristics greatly influence the potential habitat-
[[Page 14223]]
mediated effects to marine mammals (please see also the previous
discussion on masking under ``Acoustic Effects''), which may range from
local effects for brief periods of time to chronic effects over large
areas and for long durations. Depending on the extent of effects to
habitat, animals may alter their communications signals (thereby
potentially expending additional energy) or miss acoustic cues (either
conspecific or adventitious). For more detail on these concepts see,
e.g., Barber et al., 2010; Pijanowski et al., 2011; Francis and Barber,
2013; Lillis et al., 2014.
Problems arising from a failure to detect cues are more likely to
occur when noise stimuli are chronic and overlap with biologically
relevant cues used for communication, orientation, and predator/prey
detection (Francis and Barber, 2013). Although the signals emitted by
seismic airgun arrays are generally low frequency, they would also
likely be of short duration and transient in any given area due to the
nature of these surveys. As described previously, exploratory surveys
such as this one cover a large area but would be transient rather than
focused in a given location over time and therefore would not be
considered chronic in any given location.
In summary, activities associated with the proposed action are not
likely to have a permanent, adverse effect on any fish habitat or
populations of fish species or on the quality of acoustic habitat.
Thus, any impacts to marine mammal habitat are not expected to cause
significant or long-term consequences for individual marine mammals or
their populations.
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 the acoustic source (i.e., seismic airguns) has the potential to
result in disruption of behavioral patterns for individual marine
mammals. There is also some potential for auditory injury (Level A
harassment) to result, primarily for high frequency species because
predicted auditory injury zones are larger than for low-frequency
species, mid-frequency species, phocids, and otariids. However as a
precaution, small numbers of takes by Level A harassment are proposed
for authorization for all species listed in Table 1 as likely to occur
in the proposed survey area. This auditory injury is expected to be, at
most, low level PTS and the proposed mitigation and monitoring measures
are expected to further minimize the severity of such taking to the
extent practicable.
As described previously, no 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
Using the best available science, NMFS has developed 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 for non-explosive sources--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). Based on what the available science indicates
and the practical need to use a threshold based on a factor that is
both predictable and measurable for most activities, NMFS uses a
generalized acoustic threshold based on received level to estimate the
onset of behavioral harassment. NMFS predicts that marine mammals are
likely to be behaviorally harassed in a manner we consider Level B
harassment when exposed to underwater anthropogenic noise above
received levels of 120 dB re 1 [mu]Pa (rms) for continuous (e.g.,
vibratory pile-driving, drilling) and above 160 dB re 1 [mu]Pa (rms)
for non-explosive impulsive (e.g., seismic airguns) or intermittent
(e.g., scientific sonar) sources. L-DEO's proposed activity includes
the use of impulsive seismic sources. Therefore, the 160 dB re 1 [mu]Pa
(rms) criteria is applicable for analysis of level B harassment.
Level A harassment for non-explosive sources--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
https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance.
[[Page 14224]]
Table 2--Thresholds Identifying the Onset of Permanent Threshold Shift in Marine Mammals
----------------------------------------------------------------------------------------------------------------
PTS onset thresholds
Hearing group ------------------------------------------------------------------------
Impulsive * Non-impulsive
----------------------------------------------------------------------------------------------------------------
Low-Frequency (LF) Cetaceans........... Lpk,flat: 219 dB; LE,LF,24h: 199 dB.
LE,LF,24h: 183 dB.
Mid-Frequency (MF) Cetaceans........... Lpk,flat: 230 dB; LE,MF,24h: 198 dB.
LE,MF,24h: 185 dB.
High-Frequency (HF) Cetaceans.......... Lpk,flat: 202 dB; LE,HF,24h: 173 dB.
LE,HF,24h: 155 dB.
Phocid Pinnipeds (PW) (Underwater)..... Lpk,flat: 218 dB; LE,PW,24h: 201 dB.
LE,PW,24h: 185 dB.
Otariid Pinnipeds (OW) (Underwater).... Lpk,flat: 232 dB; LE,OW,24h: 219 dB.
LE,OW,24h: 203 dB.
----------------------------------------------------------------------------------------------------------------
Note: * 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]Pa2s. 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 that will feed into identifying the area ensonified above the
acoustic thresholds, which include source levels and transmission loss
coefficient.
The proposed surveys would acquire data with the 36-airgun array
with a total discharge of 6,600 in\3\ at a maximum tow depth of 12 m.
L-DEO model results are used to determine the 160-dBrms radius for the
36-airgun array and 40-in\3\ airgun at a 12-m tow depth in deep water
(>1,000 m) down to a maximum water depth of 2,000 m. Received sound
levels were predicted by L-DEO's model (Diebold et al., 2010) which
uses ray tracing for 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). In
addition, propagation measurements of pulses from the 36-airgun array
at a tow depth of 6 m have been reported in deep water (~1,600 m),
intermediate water depth on the slope (~600-1,100 m), and shallow water
(~50 m) in the Gulf of Mexico (GoM) in 2007-2008 (Tolstoy et al. 2009;
Diebold et al. 2010).
For deep and intermediate-water cases, the field measurements
cannot be used readily to derive Level A and Level B isopleths, as at
those sites the calibration hydrophone was located at a roughly
constant depth of 350-500 m, which may not intersect all the sound
pressure level (SPL) isopleths at their widest point from the sea
surface down to the maximum relevant water depth for marine mammals of
~2,000 m. At short ranges, where the direct arrivals dominate and the
effects of seafloor interactions are minimal, the data recorded at the
deep and slope sites are suitable for comparison with modeled levels at
the depth of the calibration hydrophone. At longer ranges, the
comparison with the mitigation model--constructed from the maximum SPL
through the entire water column at varying distances from the airgun
array--is the most relevant.
In deep and intermediate-water depths, comparisons at short ranges
between sound levels for direct arrivals recorded by the calibration
hydrophone and model results for the same array tow depth are in good
agreement (Fig. 12 and 14 in Appendix H of the NSF-USGS, 2011).
Consequently, isopleths falling within this domain can be predicted
reliably by the L-DEO model, although they may be imperfectly sampled
by measurements recorded at a single depth. At greater distances, the
calibration data show that seafloor-reflected and sub-seafloor-
refracted arrivals dominate, whereas the direct arrivals become weak
and/or incoherent. Aside from local topography effects, the region
around the critical distance is where the observed levels rise closest
to the mitigation model curve. However, the observed sound levels are
found to fall almost entirely below the mitigation model. Thus,
analysis of the GoM calibration measurements demonstrates that although
simple, the L-DEO model is a robust tool for conservatively estimating
isopleths.
In shallow water (<100 m), the depth of the calibration hydrophone
(18 m) used during the GoM calibration survey was appropriate to sample
the maximum sound level in the water column, and the field measurements
reported in Table 1 of Tolstoy et al. (2009) for the 36-airgun array at
a tow depth of 6 m can be used to derive isopleths.
For deep water (>1,000 m), we use the deep-water radii obtained
from L-DEO model results down to a maximum water depth of 2,000 m. The
radii for intermediate water depths (100-1,000 m) are derived from the
deep-water ones by applying a correction factor (multiplication) of
1.5, such that observed levels at very near offsets fall below the
corrected mitigation curve (Fig. 16 in Appendix H of the NSF-USGS,
2011).
The shallow-water radii are obtained by scaling the empirically
derived measurements from the GoM calibration survey to account for the
differences in tow depth between the calibration survey (6 m) and the
proposed survey (12 m); whereas the shallow water in the GoM may not
exactly replicate the shallow water environment at the proposed survey
site, it has been shown to serve as a good and very conservative proxy
(Crone et al. 2014). A simple scaling factor is calculated from the
ratios of the isopleths determined by the deep-water L-DEO model, which
are essentially a measure of the energy radiated by the source array.
Measurements have not been reported for the single 40-in\3\ airgun.
L-DEO model results are used to determine the 160 dBrms
radius for the 40-in\3\ airgun at a 12-m tow depth in deep water (Fig.
A-3 in the IHA application). For intermediate-water depths, a
correction factor of 1.5 was applied to the deep-water model results.
For shallow water, a scaling of the field measurements obtained for the
36-airgun array was used.
L-DEO's modeling methodology is described in greater detail in the
IHA application. The estimated distances to the Level B harassment
isopleth for the
[[Page 14225]]
Langseth's 36-airgun array and single 40-in\3\ airgun are shown in
Table 3.
Table 3--Predicted Radial Distances From R/V Langseth Seismic Source to Isopleths Corresponding to Level B
Harassment Threshold
----------------------------------------------------------------------------------------------------------------
Predicted distances (in
Source and volume Tow depth (m) Water depth m) to the 160-dB
(m) received sound level
----------------------------------------------------------------------------------------------------------------
Single Bolt airgun, 40 in\3\........................... 12 >1,000 \1\ 431
100-1,000 \2\ 647
<100 \3\ 1,041
4 strings, 36 airguns, 6,600 in\3\..................... 12 >1,000 \1\ 6,733
100-1,000 \2\ 10,100
<100 \3\ 25,494
----------------------------------------------------------------------------------------------------------------
\1\ Distance is based on L-DEO model results.
\2\ Distance is based on L-DEO model results with a 1.5 x correction factor between deep and intermediate water
depths.
\3\ Distance is based on empirically derived measurements in the GoM with scaling applied to account for
differences in tow depth.
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 software program and the
NMFS User Spreadsheet, described below. The updated acoustic thresholds
for impulsive sounds (e.g., airguns) contained in the Technical
Guidance were presented as dual metric acoustic thresholds using both
SELcum and peak sound pressure metrics (NMFS 2016a). 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 SELcum 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
SELcum 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 SELcum and peak SPL for the Langseth
airgun array were derived from calculating the modified farfield
signature (Table 4). 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 Level B harassment 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. For a more complete explanation of this modeling approach,
please see ``Appendix A: Determination of Mitigation Zones'' in the IHA
application.
Table 4--Modeled Source Levels Based on Modified Farfield Signature for the R/V Langseth 6,600 in\3\ Airgun Array, and Single 40 in\3\ Airgun
--------------------------------------------------------------------------------------------------------------------------------------------------------
Low frequency Mid frequency High frequency Phocid Pinnipeds Otariid Pinnipeds
cetaceans cetaceans cetaceans (underwater) (underwater)
(Lpk,flat: 219 (Lpk,flat: 230 (Lpk,flat: 202 (Lpk,flat: 218 (Lpk,flat: 232
dB; LE,LF,24h: dB; LE,MF,24h: dB; LE,HF,24h: dB; LE,HF,24h: dB; LE,HF,24h:
183 dB) 185 dB) 155 dB) 185 dB) 27462 dB)
--------------------------------------------------------------------------------------------------------------------------------------------------------
6,600 in\3\ airgun array (Peak SPLflat).................. 252.06 252.65 253.24 252.25 252.52
6,600 in\3\ airgun array (SELcum)........................ 232.98 232.84 233.10 232.84 232.08
40 in\3\ airgun (Peak SPLflat)........................... 223.93 N.A. 223.92 223.95 N.A.
40 in\3\ airgun (SELcum)................................. 202.99 202.89 204.37 202.89 202.35
--------------------------------------------------------------------------------------------------------------------------------------------------------
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
[[Page 14226]]
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 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 source velocities
and shot intervals provided in the IHA application, potential radial
distances to auditory injury zones were then calculated for
SELcum thresholds.
Inputs to the User Spreadsheets in the form of estimated SLs are
shown in Table 4. User Spreadsheets used by L-DEO to estimate distances
to Level A harassment isopleths for the 36-airgun array and single 40
in\3\ airgun for the surveys are shown is Tables A-2, A-3, A-5, and A-8
in Appendix A of the IHA application. Outputs from the User
Spreadsheets in the form of estimated distances to Level A harassment
isopleths for the surveys 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 (SELcum and Peak
SPLflat) is exceeded (i.e., metric resulting in the largest
isopleth).
Table 5--Modeled Radial Distances (m) to Isopleths Corresponding to Level A Harassment Thresholds
--------------------------------------------------------------------------------------------------------------------------------------------------------
Low frequency Mid frequency High frequency Phocid Pinnipeds Otariid Pinnipeds
cetaceans cetaceans cetaceans (underwater) (underwater)
(Lpk,flat: 219 (Lpk,flat: 230 (Lpk,flat: 202 (Lpk,flat: 218 (Lpk,flat: 232
dB; LE,LF,24h: dB); LE,MF,24h: dB); LE,HF,24h: dB); LE,HF,24h: dB); LE,HF,24h:
183 dB) 185 dB) 155 dB) 185 dB) 203 dB)
--------------------------------------------------------------------------------------------------------------------------------------------------------
6,600 in\3\ airgun array (Peak SPLflat).................. 38.9 13.6 268.3 43.7 10.6
6,600 in\3\ airgun array (SELcum)........................ 40.1 N.A. 0.1 1.3 N.A.
40 in\3\ airgun (Peak SPLflat)........................... 1.76 N.A. 12.5 1.98 N.A.
40 in\3\ airgun (SELcum)................................. 2.38 N.A. N.A. N.A. N.A.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note that because of some of the assumptions included in the
methods used, isopleths produced may be overestimates to some degree,
which will ultimately result in some degree of overestimate 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.
Marine Mammal Occurrence
In this section we provide the information about the presence,
density, or group dynamics of marine mammals that will inform the take
calculations.
In the proposed survey area in the Gulf of Alaska, L-DEO determined
the best marine mammal density data to be habitat-based stratified
marine mammal densities developed by the U.S. Navy for assessing
potential impacts of training activities in the GOA (DoN 2014).
Alternative density estimates available for species in this region are
not stratified by water depth and therefore do not reflect the known
variability in species distribution relative to habitat features.
Consistent with Rone et al. (2014), four strata were defined: 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. Densities corresponding to these strata were based on
data from several different sources, including Navy funded line-
transect surveys in the GOA as described below and in Appendix B.
To develop densities specific to the GOA, the Navy conducted two
comprehensive marine mammal surveys in the Temporary Marine Activities
Area (TMAA) in the GOA prior to 2014. The first survey was conducted
from 10 to 20 April 2009 and the second was from 23 June to 18 July
2013. Both surveys used systematic line-transect survey protocols
including visual and acoustic detection methods (Rone et al. 2010; Rone
et al. 2014). The data were collected in four strata that were designed
to encompass the four distinct habitats within the TMAA and greater
GOA. Rone et al. (2014) provided stratified line-transect density
estimates used in this analysis for fin, humpback, blue, sperm, and
killer whales, as well as northern fur seals (Table 6). Data from a
subsequent survey in 2015 were used to calculate alternative density
estimates for several species (Rone et al. 2017) and the density
estimates for Dall's porpoise used here were taken from that source.
DoN (2014) derived gray whale densities in two zones, nearshore (0-
2.25 n.mi from shore) and offshore (from 2.25-20 nmi from shore). In
our calculations, the nearshore density was used to represent the
inshore zone and the offshore density was used to represent the slope
zone.
Harbor porpoise densities in DoN (2014) were derived from Hobbs and
Waite (2010) which included additional shallow water depth strata. The
density estimate from the 100 m to 200 m depth strata was used to
represent the entire inshore zone (<1,000 m) in this analysis.
Harbor seals typically remain close to shore so minimal estimates
were used for the three deep water zones. To account for increased
inshore density, a one thousand fold increase of the minimal density
was assumed to represent the entire inshore zone (DoN 2014).
Densities for Minke whale, Pacific white-sided dolpin, and Cuvier's
and Baird's beaked whales were based on Waite (2003 in DoN 2009).
Although sei whale sightings and Stejneger's beaked whale acoustic
detections were recorded during the Navy funded GOA surveys, data were
insufficient to calculate densities for these species, so predictions
from a global model of marine mammals densities were used (DoN 2014).
Steller sea lion and northern elephant seal densities were
calculated using shore-based population estimates divided by the area
of the GOA Large Marine Ecosystem (DoN 2014).
The North Pacific right whale, Risso's dolphin, and California sea
lion are only rarely observed in or near the survey area, so minimal
densities were used to represent their potential presence.
[[Page 14227]]
However, in the North Pacific right whale critical habitat off of
Kodiak Island, it is reasonable to expect a higher density. In this
critical habitat area, the Alaska Fisheries Science Center (LOA
application available here: https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-research-and-other-activities) used a conservative density estimate based on
acoustic detections (Rone et al. 2014) and photo identifications
throughout the entirety of the Gulf of Alaska. For the portion of L-
DEO's activities that occur in North Pacific right whale critical
habitat, NMFS will use this more conservative density estimate (Table
6).
All densities were corrected for perception bias [f(0)] but only
harbor porpoise densities were corrected for availability bias [g(0)],
as described by the respective authors. There is some uncertainty
related to the estimated density data and the assumptions used in their
calculations, as with all density data estimates. However, the approach
used here is based on the best available data and are stratified by the
water depth (habitat) zones present within the survey area. These depth
stratified densities allow L-DEO to better capture known variability in
species distribution in the Gulf of Alaska, and accurately assess
impacts. Alternative density estimates were available for species in
this region, such as those used by the Alaska Fisheries Science Center
(AFSC) (AFSC LOA application available here: https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-research-and-other-activities). AFSC density values
were not stratified by water depth and represented marine mammal
density throughout the entire Gulf of Alaska. While some density
estimates provided in the AFSC application are more conservative, the
relative proximity of surveys that generated DoN estimates and L-DEO's
consideration and inclusion of publically available newer values from
Rone et al. (2017) mean the calculated exposures that are based on
these densities are best estimates for L-DEO's proposed survey.
Table 6--Marine Mammal Density Values in the Proposed Survey Area and Source
----------------------------------------------------------------------------------------------------------------
Estimated density (#/1,000 km \2\)
----------------------------------------------------------------
Offshore Seamount (in
Species \1\ Inshore Slope (1,000 m (offshore of defined Source
(<1,000 m) to Aleutian Aleutian seamount
trench) trench) areas)
----------------------------------------------------------------------------------------------------------------
LF Cetaceans:
North Pacific Right Whale. \2\ 0.00001 \2\ 0.00001 \2\ 0.00001 \2\ 0.00001 DoN (2014).
Humpback Whale............ 0.129 0.0002 0.001 0.001 Rone et al.
(2014) (Table
16).
Blue whale................ 0.0005 0.0005 0.0005 0.002 Rone et al.
(2014) (Table
16).
Fin Whale................. 0.071 0.014 0.021 0.005 Rone et al.
(2014) (Table
16).
Sei Whale................. 0.0001 0.0001 0.0001 0.0001 DoN (2014),
adapted from
Figure 5-24.
Minke Whale............... 0.0006 0.0006 0.0006 0.0006 DoN (2014).
Gray Whale................ \3\ 0.04857 \3\ 0.00243 \3\ 0 \3\ 0 DoN (2014)
MF Cetaceans:
Sperm Whale............... 0 0.0033 0.0013 0.00036 DoN (2014).
Killer Whale.............. 0.005 0.02 0.002 0.002 Rone et al.
(2014) (Table
14).
Pacific White-Sided 0.0208 0.0208 0.0208 0.0208 DoN (2014).
Dolphin.
Cuvier's Beaked Whale..... 0.0022 0.0022 0.0022 0.0022 Waite (2003) in
DoN (2014)
Baird's Beaked Whale...... 0.0005 0.0005 0.0005 0.0005 DoN (2014).
Stejneger's Beaked Whale.. \4\ 0.00001 0.00142 0.00142 0.00142 DoN (2014),
adapted from
Figure 9-12.
Risso's Dolphin........... 0.00001 0.00001 0.00001 0.00001 DoN (2014).
HF Cetaceans:
Harbor Porpoise........... 0.0473 0 0 0 Hobbes and Waite
(2010) in DoN
(2014).
Dall's Porpoise........... 0.218 0.196 0.037 0.024 Rone et al.
(2017).
Otarrid Seals:
Steller Sea Lion.......... 0.0098 0.0098 0.0098 0.0098 DoN (2014).
California Sea Lion....... 0.00001 0.00001 0.00001 0.00001 DoN (2014).
Northern Fur Seal......... 0.015 0.004 0.017 0.006 Rone et al.
(2014) (Table
14).
Phocid Seals:
Northern Elephant Seal.... 0.0022 0.0022 0.0022 0.022 DoN (2014).
Harbor Seal............... 0.01 0.00001 0.00001 0.00001 DoN (2014).
----------------------------------------------------------------------------------------------------------------
\1\ No stock specific densities are available so densities are assumed equal for all stocks present.
\2\ For North Pacific right whales, estimated density within the Kodiak Island critical habitat is 0.0053
animals/km\2\, based on detections from the GOALSII survey (Rone et al. 2014), the assumed use of the critical
habitat by all right whales in the Gulf of Alaska (Wade et al. 2011a), and a conservative correction factor.
\3\ Gray whale density was defined in two zones, nearshore (0-2.25 n.mi from shore) and offshore (from 2.25-20
nmi from shore). In our calculations, the nearshore density was used to represent the inshore zone and the
offshore density was used to represent the slope zone. In areas further offshore than the slope, density was
assumed to be 0.
\4\ Stejneger's whale are generally found in slope waters, therefore, assuming minimal inshore density.
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 harassment or Level B harassment, radial
distances from the airgun array to predicted isopleths corresponding to
the Level A harassment and Level B
[[Page 14228]]
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 harassment and Level B harassment thresholds. The area estimated to
be ensonified in a single day of the survey is then calculated (Table
7), based on the areas predicted to be ensonified around the array and
the estimated trackline distance traveled per day. This number is then
multiplied by the number of survey days. Active seismic operations are
planned for 18 days during this Gulf of Alaska survey.
Table 7--Areas (km\2\) Estimated To Be Ensonified to Level A and Level B Harassment Thresholds, per Day for Gulf of Alaska Survey
--------------------------------------------------------------------------------------------------------------------------------------------------------
Daily Total
Criteria (dB) ensonified Total survey 25 percent ensonified Relevant
area (km) days increase area (km) isopleth (m)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Level B
--------------------------------------------------------------------------------------------------------------------------------------------------------
Inshore \1\............................................. 160 19,63.1 18 1.25 44,170.3 10,100
Slope................................................... 160 684.1 18 1.25 15,392.8 6,733
Offshore................................................ 160 1,159.5 18 1.25 26,087.8 6,733
Seamount................................................ 160 1,19.8 18 1.25 2,695.2 6,733
--------------------------------------------------------------------------------------------------------------------------------------------------------
Level A
--------------------------------------------------------------------------------------------------------------------------------------------------------
LF Cetacean............................................. .............. 19.6 18 1.25 441.1 40.1
MF Cetacean............................................. .............. 6.6 18 1.25 149.6 13.6
HF Cetacean............................................. .............. 131.1 18 1.25 2,950.8 268.3
Otarid.................................................. .............. 5.2 18 1.25 116.6 10.6
Phocid.................................................. .............. 21.4 18 1.25 480.6 43.7
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Includes area ensonified above 160 dB in waters <100 m deep using an isopleth distance of 25,493 m. See application for further explanation.
The product is then multiplied by 1.25 to account for the
additional 25 percent contingency. This results in an estimate of the
total areas (km\2\) expected to be ensonified to the Level A harassment
and Level B harassment thresholds. The marine mammals predicted to
occur within these respective areas, based on estimated densities, are
assumed to be incidentally taken. Estimated exposures for the Gulf of
Alaska seismic survey are shown in Table 8.
Table 8--Estimated Level A and Level B Exposures, and Percentage of Stock or Population Exposed During Gulf of
Alaska Survey
----------------------------------------------------------------------------------------------------------------
Percentage of
Stock Level B \1\ Level A \1\ Stock size stock
----------------------------------------------------------------------------------------------------------------
LF Cetaceans:
North Pacific Right Whale. Eastern North \2\ 11 0 31 (\3\)
Pacific.
Humpback Whale............ Central North \4\ 5,101 \5\ 1 11,398 (\3\)
Pacific (Hawaii
DPS) \3\.
Central North \4\ 602 3,264 18.44
Pacific (Mexico
DPS) \3\.
Western North \4\ 29 1,107 2.62
Pacific \3\.
Blue whale................ Eastern North 48 \5\ 1 1,647 2.98
Pacific.
Central North 133 (\3\)
Pacific.
Fin Whale................. Northeast 3,912 1 \6\ 3,168 (\3\)
Pacific.
Sei Whale................. Eastern North 8 1 519 1.73
Pacific.
Minke Whale............... Alaska.......... 53 1 \7\ 1,233 4.38
Gray Whale................ Eastern North 2,182 \5\ 1 26,960 8.10
Pacific.
Western North 175 (\3\)
Pacific.
MF Cetaceans:
Sperm Whale............... North Pacific... 85 1 \8\ 345 24.93
Killer Whale.............. Alaska Resident. 586 \5\ 1 2,347 25.01
Gulf of Alaska, 587 (\3\)
Aleutian
Islands, and
Bering Sea
Transient.
Offshore........ 240 (\3\)
Pacific White-Sided North Pacific... 1,837 1 26,880 6.84
Dolphin.
Cuvier's Beaked Whale..... Alaska.......... 194 1 \9\ NA NA
Baird's Beaked Whale...... Alaska.......... 44 1 \9\ NA NA
Stejneger's Beaked Whale.. Alaska.......... 63 1 \9\ NA NA
Risso's Dolphin........... CA/OR/WA........ \10\ 16 1 6,336 0.27
HF Cetaceans:
Harbor Porpoise........... Gulf of Alaska.. \11\ 1,879 \5\ 3 31,046 \11\ 6.06
Southeast Alaska \11\ 209 975 \11\ 21.74
Dall's Porpoise........... Alaska.......... 13,656 21 83,400 16.44
Otarrid Seals:
Steller Sea Lion.......... Eastern U.S..... 865 \5\ 1 41,638 2.08
[[Page 14229]]
Western U.S..... 54,267 1.60
California Sea Lion....... U.S............. \12\ 1 1 296,750 0.00067
Northern Fur Seal......... Eastern Pacific. 1,183 1 620,660 0.19
Phocid Seals:
Northern Elephant Seal.... California 194 1 179,000 0.11
Breeding.
Harbor Seal............... South Kodiak.... 442 \5\ 1 19,199 2.31
Cook Inlet/ 27,386 1.62
Shelikof Strait.
Prince William 29,889 1.48
Sound.
----------------------------------------------------------------------------------------------------------------
\1\ Conservatively where less than 1 take by Level A harassment was calculated, we are rounding up to propose
authorizing 1 take by Level A harassment. Therefore, unless otherwise noted, all calculated takes by Level B
harassment have been reduced by the number of authorized takes by Level A harassment. This prevents double
counting of takes across the two levels of harassment.
\2\ NMFS feels that take by Level A harassment of North Pacific right whale can be effectively avoided based on
mitigation and monitoring measures, and therefore has not proposed to authorize a take by Level A harassment
for the species.
\3\ The percentage of these stocks expected to experience take is discussed further in the Small Numbers section
later in the document.
\4\ Takes are allocated amongst the three DPSs in the area based on Wade et al. 2016 (0.5% WNP, 89.0% Hawaii
DPS, 10.5% Mexico DPS). Because of rounding, the total take is higher than calculated. Population sizes for
the Hawaii and Mexican DPSs are provided in 81 FR 62259 (effective October 11, 2016).
\5\ Where multiple stocks are being affected, for the purposes of calculating the percentage of the stock
impacted, the single Level A take is being analyzed as if it occurred within each stock.
\6\ Fin whale abundance estimate is the highest of Rone et al. (2017) estimates. Based on the limited footprint
of the surveys that lead to this estimate, the true abundance of the stock is expected to be much higher.
\7\ Minke whale abundance estimates is from Zerbini et al. (2006).
\8\ Sperm whale abundance estimates is the maximum value from Rone et al. (2017).
\9\ For beaked whales, there is no accepted estimates of abundance for the Alaska stocks.
\10\ The requested number of takes by Level B harassment for Risso's dolphin has been increased to 16, the
average group size. Because this is a qualitative estimate, this take request has not been reduced by 1 to
facilitate the requested take by Level A harassment.
\11\ Based on the range of the Southeast Alaska stock of harbor porpoises, they are expected to be very rare in
the area (See ``Description of Marine Mammals in the Area of Specified Activities''). We therefore
conservatively assume that at most, 10 percent of takes will occur from the Southeast Alaska population. The
numbers for both Gulf of Alaska and Southeast Alaska stocks reflect this assumption. Because of rounding, the
total take between the two stocks is higher than the original calculation.
\12\ Only 1 take by Level B harassment was requested for California sea lion, but a take by Level A harassment
was also requested. Therefore, the amount of take by Level B harassment has not be reduced by the proposed
numbers of take by Level A harassment.
It should be noted that the proposed take numbers shown in Table 8
are expected to be conservative for several reasons. First, in the
calculations of estimated take, 25 percent has been added in the form
of operational survey days to account for the possibility of additional
seismic operations associated with airgun testing and repeat coverage
of any areas where initial data quality is sub-standard, and in
recognition of the uncertainties in the density estimates used to
estimate take as described above. Additionally, marine mammals would be
expected to move away from a loud sound source that represents an
aversive stimulus, such as an airgun array, potentially reducing the
number of takes by Level A harassment. However, the extent to which
marine mammals would move away from the sound source is difficult to
quantify and is, therefore, not accounted for in the take estimates.
Note that for North Pacific right whales and Risso's dolphin, we
propose to authorize a different number of incidental takes than the
number of incidental takes requested by L-DEO (see Table 6 in the IHA
application for requested take numbers). For Risso's dolphin, we
proposed to authorize take by Level B harassment of an average sized
group, 16 individuals, instead of the single individual requested by L-
DEO. Our rational for North Pacific right whale take is described
below.
For North Pacific right whale, there is evidence of a much higher
density in the critical habitat south of Kodiak Island (Table 6). This
density value of 0.0053 animals/km\2\ is based on detections from the
GOALSII survey (4 individuals) (Rone et al. 2014), the assumed use of
the critical habitat by all right whales in the Gulf of Alaska (Wade et
al 2011a), and a conservative correction factor (4), all divided by the
area of the critical habitat (3,042.2 km\2\). To account for this
habitat, NMFS used the Alaska Protected Resources Division Species
Distribution Mapper (https://www.fisheries.noaa.gov/resource/data/alaska-endangered-species-and-critical-habitat-mapper-web-application)
to determine a conservative approximation of L-DEO's survey path
through the critical habitat based on the representative tracks in
Figure 1 of the IHA Application. This measured distance was 35 km.
Because the majority of this habitat is inside of the 100 m isopleth,
the predicted distance to the 160-dB received sound level would be
~25.5 km. This resulted in a portion of the critical habitat 35 km long
by 51 km wide (25.5 km on each side of the survey track), or 1,785
km\2\ being ensonified. Applying the higher density of 0.0053 animals/
km\2\ to this area, results in an estimate of 9.46 North Pacific right
whales exposed to Level B harassment in the critical habitat. No
further correction, such as the 25 percent operation day increase, is
needed for the estimate in the critical habitat, because the density of
0.0053 animals/km\2\ has already been corrected to be highly
conservative (AFSC Application, Table 6-10d). To account for the rest
of the survey occurring outside of the critical habitat, the minimal
density presented in DoN (2014), 0.00001 individuals/km\2\, was used
for the remainder of the survey. The expected take in the rest of the
survey is 1.10 individuals. Summing these two estimates for take, in
both the critical habitat and remainder of survey, results in an
expected take of 10.56 individuals (rounded to 11 individuals). With
other species one calculated take was conservatively assumed to be a
take by Level A harassment (Table 8), however no takes by Level A
harassment are proposed for authorization for North Pacific right whale
given the low density of the species and NMFS evaluation of the
effectiveness of mitigation and monitoring measures.
[[Page 14230]]
Effects of Specified Activities on Subsistence Uses of Marine Mammals
The availability of the affected marine mammal stocks or species
for subsistence uses may be impacted by this activity. The subsistence
uses that may be affected and the potential impacts of the activity on
those uses are described below. Measures included in this IHA to reduce
the impacts of the activity on subsistence uses are described in the
Proposed Mitigation section. Last, the information from this section
and the Proposed Mitigation section is analyzed to determine whether
the necessary findings may be made in the Unmitigable Adverse Impact
Analysis and Determination section.
In the GOA, the marine mammals that are hunted are Steller sea
lions and harbor seals. In 2011-2012, 37 harbor seals were taken from
the North Kodiak Stock and 126 harbor seals were taken from the South
Kodiak Stock by communities on Kodiak Island (Muto et al. 2016). The
number taken from the Cook Inlet/Shelikof Strait Stock for 2011-2012 is
unknown, but an average of 233 were taken from this stock annually
during 2004-2008 (Muto et al. 2016). The seasonal distribution of
harbor seal takes by Alaska Natives typically shows two distinct
hunting peaks--one during spring and one during fall and early winter;
however, seals are taken in all months (Wolfe et al. 2012). In general,
the months of highest harvest are September through December, with a
smaller peak in February/March (Wolfe et al. 2012). Harvests are
traditionally low from May through August, when harbor seals are
raising pups and molting.
In 2008, 19 Steller sea lions were taken in the Kodiak Island
region and 9 were taken along the South Alaska Peninsula (Wolfe et al.
2009). As of 2009, data on community subsistence harvests are no longer
being collected consistently so few data are available. Wolfe et al.
(2012) reported an estimated 20 sea lions taken by hunters on Kodiak
Island in 2011. The most recent 5-year period with data available
(2004-2008) shows an annual average catch of 172 steller sea lions for
all areas in Alaska combined except the Pribilof Islands in the Bering
Sea (Muto et al. 2018). Sea lions are taken from Kodiak Island in low
numbers year round (Wolfe et al. 2012).
The proposed project could potentially impact the availability of
marine mammals for harvest in a small area immediately around the
Langseth, and for a very short time period during seismic operations.
Considering the limited time that the planned seismic surveys would
take place close to shore, where most subsistence harvest of marine
mammals occurs in the Gulf of Alaska, the proposed project is not
expected to have any significant impacts to the availability of Steller
sea lions or harbor seals for subsistence harvest. Additionally, to
mitigate any possible conflict, community outreach is planned and
described further in ``Proposed Mitigation'' below.
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 such
activity, and other means of effecting the least practicable impact on
such species or stock and its habitat, paying particular attention to
rookeries, mating grounds, and areas of similar significance, and on
the availability of such species or stock for taking for certain
subsistence uses. NMFS regulations require applicants for incidental
take authorizations to include information about the availability and
feasibility (economic and technological) of equipment, methods, and
manner of conducting such 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, as
well as subsistence uses. This considers the nature of the potential
adverse impact being mitigated (likelihood, scope, range). It further
considers the likelihood that the measure will be effective if
implemented (probability of accomplishing the mitigating result if
implemented as planned) the likelihood of effective implementation
(probability implemented as planned) and;
(2) the practicability of the measures for applicant
implementation, which may consider such things as cost, 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.
L-DEO has reviewed mitigation measures employed during seismic
research surveys authorized by NMFS under previous incidental
harassment authorizations, as well as recommended best practices in
Richardson et al. (1995), Pierson et al. (1998), Weir and Dolman
(2007), Nowacek et al. (2013), Wright (2014), and Wright and Cosentino
(2015), and has incorporated a suite of proposed mitigation measures
into their project description based on the above sources.
To reduce the potential for disturbance from acoustic stimuli
associated with the activities, L-DEO has proposed to implement
mitigation measures for marine mammals. Mitigation measures that would
be adopted during the proposed surveys include (1) Vessel-based visual
mitigation monitoring; (2) Vessel-based passive acoustic monitoring;
(3) Establishment of an exclusion zone; (4) Power down procedures; (5)
Shutdown procedures; (6) Ramp-up procedures; (7) Vessel strike
avoidance measures; and (8) Sensitive Habitat Measures.
Vessel-Based Visual Mitigation Monitoring
Visual monitoring requires the use of trained observers (herein
referred to as visual PSOs) to scan the ocean surface visually for the
presence of marine mammals. The area to be scanned visually includes
primarily the exclusion zone, but also the buffer zone. The buffer zone
means an area beyond the exclusion zone to be monitored for the
presence of marine mammals that may enter the exclusion zone. During
pre-clearance monitoring (i.e., before ramp-up begins), the buffer zone
also acts as an extension of the exclusion zone 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
exclusion zone, out to a radius of 1,000 m from the edges of the airgun
array (500-1,000 m). Visual monitoring of the exclusion zones 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 close 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-clearance, and (2)
during airgun use, aid in establishing and maintaining the
[[Page 14231]]
exclusion zone by alerting the visual observer and crew of marine
mammals that are outside of, but may approach and enter, the exclusion
zone.
L-DEO must use at least five dedicated, trained, NMFS-approved
Protected Species Observers (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 aboard the
vessel must have a minimum of 90 days at-sea experience working in
those roles, respectively, during a deep penetration (i.e., ``high
energy'') seismic survey, 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 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) and 30 minutes prior to and during
nighttime ramp-ups of the airgun array. Visual monitoring of the
exclusion and buffer zones must begin no less than 30 minutes prior to
ramp-up and 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 airgun (i.e., anytime the acoustic source is
active, including ramp-up), occurrences of marine mammals within the
buffer zone (but outside the exclusion zone) shall be communicated to
the operator to prepare for the potential shutdown or powerdown 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 four 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 exclusion zone 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.
Passive acoustic monitoring (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. Acoustical 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 call, 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 four 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 two hours
without acoustic monitoring during daylight hours only under the
following conditions:
Sea state is less than or equal to BSS 4;
No marine mammals (excluding delphinids) detected solely
by PAM in the applicable exclusion zone in the previous two hours;
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
Operations with an active acoustic source, but without an
operating PAM system, do not exceed a cumulative total of four hours in
any 24-hour period.
Establishment of an Exclusion Zone and Buffer Zone
An exclusion zone (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 for the 36 airgun array. The 500 m EZ would be based on radial
distance from any element 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 500 m EZ is intended to be precautionary in the sense that it
would
[[Page 14232]]
be expected to contain sound exceeding the injury criteria for all
cetacean hearing groups, (based on the dual criteria of SELcum 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.
Because the North Pacific right whale is a stock of high concern,
L-DEO will implement a shutdown if the species is observed at any
distance. In addition, when transiting through North Pacific right
whale critical habitat, L-DEO must do any such transit during daylight
hours, to facilitate the ability of PSOs to observe any right whales
that may be present. Additionally, for high risk circumstances, such as
observation of a calf or aggregation of whales, L-DEO will shutdown if
these circumstances are observed at any distance.
Finally, to minimize impact on fin whales in their feeding BIA near
Kodiak Island, L-DEO must observe a larger EZ for this species while in
the BIA. If a fin whale or group of fin whales is observed with 1,500 m
of the acoustic source within the fin whale BIA, L-DEO must implement a
shutdown.
Pre-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 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-
clearance observation (30 minutes) is to ensure no protected species
are observed within the buffer zone prior to the beginning of ramp-up.
During pre-clearance is the only time observations of protected species
in the buffer zone would prevent operations (i.e., the beginning of
ramp-up). The intent of ramp-up is to warn protected species 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-
clearance and ramp-up requirements:
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 exclusion and buffer zones
for 30 minutes prior to the initiation of ramp-up (pre-clearance).
Ramp-ups shall be scheduled so as to minimize the time
spent with the source activated prior to reaching the designated run-
in.
One of the PSOs conducting pre-clearance observations must
be notified again immediately prior to initiating ramp-up procedures
and the operator must receive confirmation from the PSO to proceed.
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 applicable exclusion zone or the buffer zone during
the 30 minute pre-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 30 minutes for all other species).
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.
PSOs must monitor the exclusion and buffer zones during
ramp-up, and ramp-up must cease and the source must be shut down upon
observation of a marine mammal within the applicable exclusion zone.
Once ramp-up has begun, observations of marine mammals within the
buffer zone do not require shutdown or powerdown, but such observation
shall be communicated to the operator to prepare for the potential
shutdown or powerdown.
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.
If the acoustic source is shut down for brief periods
(i.e., less than 30 minutes) for reasons other than that described for
shutdown and powerdown (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 exclusion zone. For
any longer shutdown, pre-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-clearance
watch of 30 min is not required.
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-clearance of 30
min.
Shutdown and Powerdown
The shutdown of an airgun array requires the immediate de-
activation of all individual airgun elements of the array while a
powerdown requires immediate de-activation of all individual airgun
elements of the array except the single 40-in\3\ airgun. Any PSO on
duty will have the authority to delay the start of survey operations or
to call for shutdown or powerdown of the acoustic source if a marine
mammal is detected within the applicable exclusion zone. 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 and powerdown 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 powerdown) and (1) a
marine mammal appears within or enters the applicable exclusion zone
and/or (2) a marine mammal (other than delphinids, see below) is
detected acoustically and localized within the applicable exclusion
zone, the acoustic source will be shut down. When shutdown is called
for by a PSO, the acoustic source will be immediately
[[Page 14233]]
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 500 m EZ. The animal would be considered
to have cleared the 500 m EZ if it is visually observed to have
departed the 500 m EZ, or it has not been seen within the 500 m EZ for
15 min in the case of small odontocetes and pinnipeds, or 30 min in the
case of mysticetes and large odontocetes, including sperm Cuvier's
beaked, Baird's beaked, Stejneger's beaked, and killer whales.
The shutdown requirement can be waived for small dolphins in which
case the acoustic source shall be powered down to the single 40-in\3\
airgun if an individual is visually detected within the exclusion zone.
As defined here, the small delphinoid 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 would apply solely to specific genera of small dolphins--
Lagenorhynchus and Grampus--The acoustic source shall be powered down
to 40-in\3\ airgun if an individual belonging to these genera is
visually detected within the 500 m exclusion zone.
Powerdown conditions shall be maintained until delphinids for which
shutdown is waived are no longer observed within the 500 m exclusion
zone, following which full-power operations may be resumed without
ramp-up. Visual PSOs may elect to waive the powerdown requirement if
delphinids for which shutdown is waived to be voluntarily approaching
the vessel for the purpose of interacting with the vessel or towed
gear, and may use best professional judgment in making this decision.
We include this small delphinid exception because power-down/
shutdown requirements for small delphinids under all circumstances
represent practicability concerns without likely commensurate benefits
for the animals in question. Small delphinids 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), 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 delphinids
commonly approach vessels and/or towed arrays during active sound
production for purposes of bow riding, with no apparent effect observed
in those delphinids (e.g., Barkaszi et al., 2012). The potential for
increased shutdowns resulting from such a measure would require the R/V
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 delphinids, they are much less likely to
approach vessels. Therefore, retaining a power-down/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 power-down/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.
Powerdown conditions shall be maintained until the marine mammal(s)
of the above listed genera are no longer observed within the exclusion
zone, following which full-power operations may be resumed without
ramp-up. Additionally, visual PSOs may elect to waive the powerdown
requirement if the small dolphin(s) appear to be voluntarily
approaching the vessel for the purpose of interacting with the vessel
or towed gear, and may use best professional judgment in making this
decision. 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 exclusion zone). If PSOs observe any behaviors in
a small delphinid for which shutdown is waived that indicate an adverse
reaction, then powerdown will be initiated immediately.
Upon implementation of shutdown, the source may be reactivated
after the marine mammal(s) has been observed exiting the applicable
exclusion zone (i.e., animal is not required to fully exit the buffer
zone where applicable) or following 15 minutes for small odontocetes
and 30 minutes for all other species with no further observation of the
marine mammal(s).
Vessel Strike Avoidance
These measures apply to all vessels associated with the planned
survey activity; however, we note that 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. These measures include the following:
1. Vessel operators and crews must maintain a vigilant watch for
all marine mammals and slow down, stop their vessel, or alter course,
as appropriate and regardless of vessel size, to avoid striking any
marine mammal. A single marine mammal at the surface may indicate the
presence of submerged animals in the vicinity of the vessel; therefore,
precautionary measures should be exercised when an animal is observed.
A visual observer aboard the vessel must monitor a vessel strike
avoidance zone around the vessel (specific distances detailed below),
to ensure the potential for strike is minimized. Visual observers
monitoring the vessel strike avoidance zone can be either third-party
observers or crew members, but crew members responsible for these
duties must be provided sufficient training to distinguish marine
mammals from other phenomena and broadly to identify a marine mammal to
broad taxonomic group (i.e., as a large whale or other marine mammal).
2. Vessel speeds must be reduced to 10 kn or less when mother/calf
pairs, pods, or large assemblages of any marine mammal are observed
near a vessel.
3. All vessels must maintain a minimum separation distance of 100 m
from large whales (i.e., sperm whales and all baleen whales).
4. All vessels must attempt to maintain a minimum separation
distance of 50 m from all other marine mammals, with an exception made
for those animals that approach the vessel.
5. When marine mammals are sighted while a vessel is underway, the
vessel
[[Page 14234]]
should 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 should reduce speed and shift
the engine to neutral, not engaging the engines until animals are clear
of the area. This recommendation does not apply to any vessel towing
gear.
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, NMFS has preliminarily determined that the mitigation
measures provide the means 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.
Sensitive Habitat Measures
Because the propose survey overlaps with BIAs and critical habitat
for some species (see MM Occurance), L-DEO will implement additional
measures related to these areas including area avoidance and the
implementation of special shutdown zones. For Steller sea lion
rookeries and major haulouts, classified as critical habitat (58 FR
45269, August 27, 1993). Steller sea lions maintain rookeries and major
haul-outs in the area of L-DEO's survey (Figure 1 in the IHA
Application). Additionally the timing of the survey overlaps with the
breeding season of Steller sea lions. As such, L-DEO must observe a
three nautical mile exclusion zone around these critical habitats. This
means that L-DEO avoid transiting through and operating seismic airguns
in these areas.
A portion of L-DEO's proposed survey will also occur in the fin
whale BIA (Ferguson et al. 2015). Because of the temporal and spatial
overlap in the proposed survey and peak use of the fin whale BIA, L-DEO
will implement a shutdown if a fin whale or group of fin whales is
observed at within a 1,500 m radius from the acoustic source, within
their BIA. L-DEO will refer to Ferguson et al. (2015) for the location
of the BIA, but waters around the Semidi Islands, Kodiak Island, and
Chirikof Island generally define the portion of the BIA L-DEO is
expected to transit through.
The expected elevated density of North Pacific right whales in
their critical habitat means that additional measures are prudent for
this area. When transiting through North Pacific right whale critical
habitat, L-DEO must do any such transit during daylight hours, to
facilitate the ability of PSOs to observe any right whales that may be
present. This measure is in addition to the requirement that L-DEO must
implement a shutdown if a North Pacific right whale is observed at any
distance.
Mitigation for Subsistence Uses of Marine Mammals--Community Outreach
Although impacts on subsistence uses are not expected due to the
strong separation in time and space between marine mammal subsistence
harvest and L-DEO's proposed activities, project principle
investigators will conduct outreach with communities near the planned
project area to identify and avoid areas of potential conflict,
including for marine subsistence activities. This measure will mitigate
any potential negative impact on subsistence hunting activities,
despite there being no expected significant impact.
Based on our evaluation of the applicant's proposed measures, as
well as other measures considered by NMFS, NMFS has preliminarily
determined that the proposed mitigation measures provide the means
effecting the least practicable impact on the affected species or
stocks and their habitat, paying particular attention to rookeries,
mating grounds, and areas of similar significance, and on the
availability of such species or stock for subsistence uses.
Proposed Monitoring and Reporting
In order to issue an IHA for an activity, Section 101(a)(5)(D) of
the MMPA states that NMFS must set forth, requirements pertaining to
the monitoring and reporting of such taking. The MMPA implementing
regulations at 50 CFR 216.104 (a)(13) indicate that requests for
authorizations must include the suggested means of accomplishing the
necessary monitoring and reporting that will result in increased
knowledge of the species and of the level of taking or impacts on
populations of marine mammals that are expected to be present 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:
Occurrence of marine mammal species or stocks in the area
in which take is anticipated (e.g., presence, abundance, distribution,
density);
Nature, scope, or context of likely marine mammal exposure
to potential stressors/impacts (individual or cumulative, acute or
chronic), through better understanding of: (1) Action or environment
(e.g., source characterization, propagation, ambient noise); (2)
affected species (e.g., life history, dive patterns); (3) co-occurrence
of marine mammal species with the action; or (4) biological or
behavioral context of exposure (e.g., age, calving or feeding areas);
Individual marine mammal responses (behavioral or
physiological) to acoustic stressors (acute, chronic, or cumulative),
other stressors, or cumulative impacts from multiple stressors;
How anticipated responses to stressors impact either: (1)
Long-term fitness and survival of individual marine mammals; or (2)
populations, species, or stocks;
Effects on marine mammal habitat (e.g., marine mammal prey
species, acoustic habitat, or other important physical components of
marine mammal habitat); and
Mitigation and monitoring effectiveness.
Vessel-Based Visual Monitoring
As described above, PSO observations would take place during
daytime airgun operations and nighttime start ups (if applicable) of
the airguns. During seismic operations, at least six visual PSOs would
be based aboard the Langseth. Monitoring shall be conducted in
accordance with the following requirements:
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;
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:
[[Page 14235]]
PSOs shall be independent, dedicated, trained visual and
acoustic PSOs and must be employed by a third-party observer provider;
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);
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;
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;
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;
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;
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;
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
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:
Vessel names (source vessel and other vessels associated
with survey) and call signs;
PSO names and affiliations;
Dates of departures and returns to port with port name;
Date and participants of PSO briefings;
Dates and times (Greenwich Mean Time) of survey effort and
times corresponding with PSO effort;
Vessel location (latitude/longitude) when survey effort
began and ended and vessel location at beginning and end of visual PSO
duty shifts;
Vessel heading and speed at beginning and end of visual
PSO duty shifts and upon any line change;
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;
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
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-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:
Watch status (sighting made by PSO on/off effort,
opportunistic, crew, alternate vessel/platform);
PSO who sighted the animal;
Time of sighting;
Vessel location at time of sighting;
Water depth;
Direction of vessel's travel (compass direction);
Direction of animal's travel relative to the vessel;
Pace of the animal;
Estimated distance to the animal and its heading relative
to vessel at initial sighting;
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;
Estimated number of animals (high/low/best);
Estimated number of animals by cohort (adults, yearlings,
juveniles, calves, group composition, etc.);
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);
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);
Animal's closest point of approach (CPA) and/or closest
distance from any element of the acoustic source;
Platform activity at time of sighting (e.g., deploying,
recovering, testing, shooting, data acquisition, other); and
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:
An acoustic encounter identification number, and whether
the detection was linked with a visual sighting;
Date and time when first and last heard;
Types and nature of sounds heard (e.g., clicks, whistles,
creaks, burst pulses, continuous, sporadic, strength of signal);
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.
[[Page 14236]]
A report would be submitted to NMFS within 90 days after the end of
the cruise. The report would describe the operations that were
conducted and sightings of marine mammals near the operations. The
report would provide full documentation of methods, results, and
interpretation pertaining to all monitoring. The 90-day report would
summarize the dates and locations of seismic operations, and all marine
mammal sightings (dates, times, locations, activities, associated
seismic survey activities). The report would also include estimates of
the number and nature of exposures that occurred above the harassment
threshold based on PSO observations, including an estimate of those on
the trackline but not detected.
Reporting
L-DEO will be required to shall submit a draft comprehensive report
to NMFS on all activities and monitoring results within 90 days of the
completion of the survey or expiration of the IHA, whichever comes
sooner. The report must describe all activities conducted and sightings
of protected species near the activities, must provide full
documentation of methods, results, and interpretation pertaining to all
monitoring, and must summarize the dates and locations of survey
operations and all protected species sightings (dates, times,
locations, activities, associated survey activities). The report will
also include estimates of the number and nature of exposures that
occurred above the harassment threshold based on PSO observations,
including an estimate of those on the trackline but not detected. 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
information submitted in interim monthly reports as well as additional
data collected as described above and the IHA. The draft report must be
accompanied by a certification from the lead PSO as to the accuracy of
the report, and the lead PSO may submit directly NMFS a statement
concerning implementation and effectiveness of the required mitigation
and monitoring. A final report must be submitted within 30 days
following resolution of any comments on the draft report.
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
proposed seismic 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.
NMFS does not anticipate that serious injury or mortality would
occur as a result of L-DEO's proposed survey, even in the absence of
proposed mitigation. Thus the proposed authorization does not authorize
any mortality. As discussed in the Potential Effects section, non-
auditory physical effects, stranding, and vessel strike are not
expected to occur.
We propose to authorize a limited number of instances of Level A
and Level B harassment of 21 species of marine mammal species. For 19
of these species, a single take by Level A harassment is authorized as
a precaution. However, we believe that any PTS incurred in marine
mammals as a result of the proposed activity would be in the form of
only a small degree of PTS, not total deafness, and would be unlikely
to affect the fitness of any individuals, because of the constant
movement of both the 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 (i.e., since the duration of
exposure to loud sounds will be relatively short). Also, as described
above, we expect that marine mammals would be likely to 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 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 which, because of their
comparatively short duration, are considered to be of lower severity
and with no lasting biological consequences (e.g., Southall et al.,
2007).
Potential impacts to marine mammal habitat were discussed
previously in this document (see Potential Effects of the Specified
Activity on Marine Mammals and their Habitat). 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
(~18 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.
[[Page 14237]]
The tracklines of this survey either traverse or are proximal to
the BIAs for four baleen whale species including fin, gray, North
Pacific right, and humpback whales in U.S. waters of the Gulf of Alaska
(Ferguson et al. 2015). Additionally, there is a BIA for beluga whales
in nearby Cook Inlet, but the location of the BIA means the habitat
will not co-occur with L-DEO's survey (Ferguson et al. 2015). The North
Pacific Right whale feeding BIA east of the Kodiak Archipelago is
primarily used between June and September. The fin whale feeding BIA
that stretches from Kenai Peninsula through the Alaska Peninsula is
primarily used between June and August. The gray whale feeding BIA east
of the Kodiak Archipelago is primarily used between June and August.
For the North Pacific Right whale, gray whale, and fin whale feeding
BIAs, L-DEO's survey planned for June 1 through June 19, 2019 could
overlap with a period where BIAs represent an important habitat.
However, only of a portion of seismic survey days would actually occur
in or near these BIAs, and all survey efforts should be completed by
mid-June, still in the early window of primary use for all these BIAs.
Additionally, there mitigation measures that should further reduce take
number and severity for fin whales and North Pacific right whales.
These include the requirement to shutdown the acoustic source if a fin
whale, within the fin whale BIA, is observed within 1,500 meters of the
source and the requirement to shutdown if a North Pacific right whale
is observed at any distance from the source. The gray whale migratory
corridor BIA and humpback whale feeding BIAs overlap spatially with L-
DEO's survey, but the timing of primary use of these BIAs does not
overlap temporally with the survey. Gray whales are most commonly seen
migratory northward between March and May and southward between
November and January. As proposed, there is no possibility that L-DEO's
survey impacts the southern migration, and presence of northern
migrating individuals should be below peak during survey operations
beginning in June 2019. Additionally, humpback whale feeding BIAs in
the region are primarily used between July and August or September. L-
DEO's survey efforts should be completed before peak use of these
feeding habitats. For all habitats, no physical impacts to BIA 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 BIAs, 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 the designated BIAs.
Critical habitat has been designated for the ESA listed North
Pacific right whale and western DPS of Steller sea lions. Only a
portion of L-DEO's planned seismic survey will occur in these critical
habitats. Steller sea lion critical habitat also includes a ``no
approach'' zone within 3 nmi of rookeries. Steller sea lions both
occupy rookeries and pup from late-May through early-July (NMFS 2008),
which coincides with L-DEO's proposed survey. Thus, we are requiring
that the proposed survey avoid transiting or surveying within 3 nmi of
any rookeries. For North Pacific right whale critical habitat, L-DEO
would only need to traverse approximately 35 km of the designated
critical habitat. At a speed of approximately 9.3 km per hour (5 kn),
L-DEO would only be in the critical habitat for less than 4 hours. L-
DEO would only traverse this critical habitat during daylight hours to
facilitate the ability of PSOs to observe any right whales that may be
present, so as to reduce the potential for their exposure to airgun
noise. Additionally, L-DEO would be required to shutdown seismic
airguns if a North Pacific right whale is observed at any distance,
further minimizing the impacts on North Pacific right whales in their
critical habitat and elsewhere. The characteristics that make this
habitat an important feeding area for North Pacific right whales are
abundant planktonic food sources. While there are possible impacts of
seismic activity on plankton (McCauley et al., 2017), the currents that
flow through the Gulf of Alaska will readily refresh plankton resources
in the area. As such, this seismic activity is not expected to have a
lasting physical impact on habitat or prey within it. Any impact would
be a temporary increase in sound levels when the survey is occurring in
or near the critical habitat and resulting temporary avoidance of prey
or marine mammals themselves due these elevated sound levels.
After accounting for qualitative factors, the activity is expected
to impact a small percentage of all marine mammal stocks that would be
affected by L-DEO's proposed survey (see ``Small Numbers'' below).
Additionally, 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.
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 power downs and/
or 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.
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 species or stock
through effects on annual rates of recruitment or survival:
No mortality is anticipated or authorized;
The proposed activity is temporary and of relatively short
duration (~18 days);
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;
The number of instances of potential PTS that may occur
are expected to be very small in number.
[[Page 14238]]
Instances of potential PTS that are incurred in marine mammals would 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);
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;
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;
The proposed mitigation measures, including visual and
acoustic monitoring, power-downs, shutdowns, and enhanced measures for
areas of biological importance 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 monitoring and
mitigation measures, NMFS preliminarily finds that the total marine
mammal take from the proposed activity will have a negligible impact on
all affected marine mammal species or stocks.
Small Numbers
As noted above, only small numbers of incidental take may be
authorized under Section 101(a)(5)(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. Additionally, other qualitative factors may
be considered in the analysis, such as the temporal or spatial scale of
the activities.
There are seven stocks for which the estimated instances of take
appear high when compared to the stock abundance (Table 8), including
the Northeast Pacific fin whale stock, the North Pacific right whale
stock, the Western North Pacific gray whale stock, the Central North
Pacific blue whale stock, the Central North Pacific humpback whale
stock (Hawaii DPS), the Offshore killer whale stock, and the Gulf of
Alaska, Aleutian Islands, and Bering Sea transient killer whale stock.
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 an additional three stocks (Alaska stocks of the three beaked
whale species), there are no abundance estimates upon which to base a
comparison. However, we note that the anticipated number of incidents
of take by Level B and Level A harassment are low (46 to 196 for these
three stocks) and represent a small number of animals within these
stocks, which have extensive ranges across large parts of the North
Pacific Ocean compared to L-DEO's proposed survey area (Muto et al,
2018). Based on the broad spatial distributions of these species
relative to the proposed survey area, NMFS concludes that the
authorized take of these species represent small numbers relative to
the affected species' overall population sizes, though we are unable to
quantify the authorized take numbers as a percentage of population.
For all other stocks (aside from the seven referenced above and
described below and the three beaked whales), the authorized take is
less than 25% as compared to the stock abundance (recognizing that some
of those takes may be repeats of the same individual, thus rendering
the percentage even lower).
The expected take of the Northeast Pacific stock of fin whales
appears to impact a high percentage of the population (123.5 percent),
but this percentage is based on an occurrence estimate which surveyed
only a small portion of the range (Rone et al. 2017), and no
representative estimate of the full stock abundance is available (Muto
et al. 2018). The range of the Northeast Pacific fin whale stock
extends through much of the north Pacific (Muto et al. 2018). Based on
the small portion of the stock's range that Rone et al. (2017)
observed, the full stock abundance would be much higher than 3,168
individuals, reducing the percentage of the population that would be
impacted by take from L-DEO's activities. Additionally, L-DEO's actions
are located in a small portion of the total range and will occur within
a short period of less than a month. L-DEO's previous marine mammal
monitoring in the Gulf of Alaska reported 79 fin whales (RPS 2011) and
Zerbini et al. (2006) observed 530 fin whales across 3 years of summer
surveys in the Northern Gulf of Alaska. Given these previous
observations, it is not realistic that L-DEO will encounter 3,914
individual fin whales. Instead, given the range of the species, the
known underestimate of stock abundance, and the comparatively small
action area, combined with the short duration of the survey, it is more
likely that there will be multiple instances of take to a smaller
number of individuals that are in the action area during the proposed
survey and entirely unlikely that more than a third of the stock would
be exposed to the seismic survey.
The estimated instances of take for North Pacific right whales
appears high compared to stock abundance (35.5 percent), but
realistically 11 right whales are not likely to experience harassment.
Given the higher assumed density of whales in the critical habitat area
off of Kodiak Island, the vast majority of estimated takes would occur
in that area (see ``Take Calculation and Estimation''). Overall, right
whales are very rarely detected in the Gulf of Alaska, and most
evidence of the region's importance for the species is based on
historic whaling records (Muto et al., 2018). Either visual or acoustic
detections of a single right whale are rare in the Gulf of Alaska.
North Pacific right whales are much more commonly detected in their
Bering Sea critical habitat (73 FR 19000, April 8, 2008; Muto et al.,
2018). Given this evidence, only a small portion of the population is
expected to be present in the Gulf of Alaska and the Kodiak Island
critical habitat. As such, it is more realistic to believe there will
be multiple takes of the few individuals present, comprising less than
a third of the stock. Additionally, L-DEO proposed survey will only
impact the North Pacific right whale critical habitat for a very short
portion of their survey and there are additional mitigation measures in
place to further minimize any acoustic impacts on North Pacific right
whales.
The amount of take expected for the Western North Pacific stock
(WNP) of gray whales appears high (1247.43 percent). In reality, 2,183
individuals will be not experience take from this stock. There are two
stocks of gray whales in this area, the WNP and the Eastern North
Pacific stock (ENP). It is more realistic to apportion expected takes
between these stocks. NMFS has no commonly used method to estimate the
relative occurrence of these stocks, but here we propose to apportion
the takes between the two stocks using their relative abundances and a
correction factor to ensure this number is conservative. The total
abundance of the two stocks is 27,135 gray whales. Based on estimates
of stock size (Table 1), 0.65 percent of encountered gray whales would
be expected to come from the
[[Page 14239]]
WNP stock, and 99.35 percent would be expected to come from the ENP
stock, which results in an apportioned take estimate for each stock of
14 (WNP) and 2,169 (ENP). To represent uncertainty in this method and
produce a conservative estimate, we then double the apportioned take
for the smaller stocks, resulting in an estimated 28 takes for the WNP
stock. This estimated level of take is expected to impact an estimated
16 percent of the WNP stock. Further supporting this conclusion, the
summer feeding grounds of WNP gray whales are believed to be off the
Sakhalin Islands and other parts of coastal eastern Russia. In total,
27 to 30 whales have been observed in both the WNP and ENP, meaning
that while some whales identified on these summer grounds have been
observed overwintering in the eastern Pacific around North America,
some also migrate to Japanese and Chinese waters (Caretta et al., 2014;
Caretta et al., 2019 DRAFT). Based on relative abundance of gray whale
stocks and knowledge of behavior, the WNP stock is expected to make up
a small portion of the gray whales that will experience take from L-
DEO's activity. Therefore, it is entirely unlikely that more than a
third of the stock would be exposed to the seismic survey.
The expected instances of take of the Central North Pacific (CNP)
stock of blue whales appears high when compared to the abundance (37
percent), however, in reality 50 CNP blue whales are not likely to be
harassed. Blue whales belonging to the CNP stock appear to feed in
summer in waters southwest of Kamchatka, south of the Aleutians, and in
the Gulf of Alaska (Stafford 2003; Watkins et al. 2000). Because of
this large summer range of CNP blue whales compared to the size of L-
DEO's action area, it is more likely that there will be multiple takes
of a smaller number of individuals that would occur within the action
area, and the percentage of the stock taken will be less than a third
of the individuals.
For humpback whales, takes are apportioned between the different
stocks or DPSs present based on Wade et al. (2016). With this
apportionment, the expected instances of take of the Central North
Pacific stock's Hawaii DPS appears high (44.8 percent of the estimated
DPS abundance). In reality, 5101 Hawaii DPS humpback whales are not
likely to be harassed, as it is more likely that a smaller number of
individuals will experience multiple takes. The Gulf of Alaska is an
important center of humpback whale abundance, and L-DEO's survey
affects a portion of the Gulf of Alaska. The highest densities of
humpback whales in the Gulf of Alaska are observed between July and
August (Ferguson et al., 2015), while L-DEO's survey is planned for
June, so the survey should not overlap with peak abundance.
Additionally, there are other areas of high humpback whale density in
the Aleutian Islands and Bering Sea (Muto et al. 2018). This evidence,
plus the CNP stock's large range relative to L-DEO's action area, along
with the short duration of the survey, mean that it is more likely that
there will be multiple takes of a smaller portion of the individuals
that occur in L-DEO's action area, and fewer than a third of the
individuals in the stock will be taken.
The expected instances of take from both the Offshore and Gulf of
Alaska, Aleutian Islands, and Bering Sea transient stocks of killer
whales appears high when compared against the stock abundance (245
percent and 100.2 percent respectively). In reality, 588 individuals
will not experience take from each of these stocks. There are three
stocks of killer whales in this area, including the Eastern North
Pacific Alaska Resident stock, and it is more realistic to apportion
expected takes between these stocks. NMFS has no commonly used method
to estimate the relative occurrence of these stocks, but here we
propose to apportion the takes between the three stocks using their
relative abundances and a correction factor to ensure this number is
conservative. The total abundance of the three stocks in the area is
3,174 killer whales. Based on estimates of stock size, 73.9 percent of
encountered killer whales would be expected to come from the Alaska
resident stock, 18.5 percent would be expected to come from the Gulf of
Alaska, Aleutian Islands, and Bering Sea stock, and 7.6 percent would
be expected to come from the offshore stock, which come to a take
estimate for each stock of 434.8, 108.7 and 44.5 respectively. To
represent uncertainty in this method and produce a conservative
estimate, we then double the apportioned take for each of the smaller
stocks, resulting in an estimated 218 takes for the Gulf of Alaska,
Aleutian Islands, and Bering Sea stock and 90 takes for the Offshore
stock. Carrying these estimates along results in 37.1 percent of the
Gulf of Alaska, Aleutian Islands, and Bering Sea stock experiencing
take and 37.5 of the Offshore stock experiencing take. While these
numbers still appear high, the extensive ranges of both stocks compared
to L-DEO's action area, as well as the short duration of the survey,
mean that realistically there will be multiple takes of a smaller
portion of both killer whale stocks, resulting in no more than a third
of the individuals of any of these stocks being taken. Individuals from
the offshore stock are known to undertake large movements across their
entire range, from the Aleutian Islands to the California coast and use
numerous portions of this habitat in the spring and summer (Dahlheim et
al. 2008). The Gulf of Alaska, Aleutian Islands, and Bering Sea
transient stock occupies a range that includes all of the U.S. EEZ in
Alaska (Muto et al. 2018), with L-DEO only impacting a portion of this
range for a limited time period.
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
In order to issue an IHA, NMFS must find that the specified
activity will not have an ``unmitigable adverse impact'' on the
subsistence uses of the affected marine mammal species or stocks by
Alaskan Natives. NMFS has defined ``unmitigable adverse impact'' in 50
CFR 216.103 as an impact resulting from the specified activity: (1)
That is likely to reduce the availability of the species to a level
insufficient for a harvest to meet subsistence needs by: (i) Causing
the marine mammals to abandon or avoid hunting areas; (ii) Directly
displacing subsistence users; or (iii) Placing physical barriers
between the marine mammals and the subsistence hunters; and (2) That
cannot be sufficiently mitigated by other measures to increase the
availability of marine mammals to allow subsistence needs to be met.
In the GOA, the marine mammals that are hunted are Steller sea
lions and harbor seals. For seals, these harvests are traditionally low
from May through August, when harbor seals are raising pups and
molting. Sea lions are taken from Kodiak Island and other locations in
the action area in low numbers year round, but harvests are minimal
during late spring and summer (Wolfe et al. 2012).
L-DEO's proposed seismic survey would occur during a period of low
harbor seal and Stellar sea lion harvest, so any impact on subsistence
activities will be minimal. Additionally, the survey will occur for
approximately 18 days, and the portion of the survey that would occur
in nearshore waters, where
[[Page 14240]]
pinniped harvest is most likely, would be even shorter. L-DEO has also
planned to conduct outreach to subsistence users in the area, in order
to determine if potential use conflicts exists and avoid these
conflicts if possible. This outreach, in combination with mitigation
measures to avoid Steller sea lion rookeries and haulouts, marine
mammal monitoring, and establishing exclusion zones, will effectively
minimize impacts on these marine mammals and resulting impacts on
subsistence users.
Based on the description of the specified activity, the measures
described to minimize adverse effects on the availability of marine
mammals for subsistence purposes, and the proposed mitigation and
monitoring measures, NMFS has preliminarily determined that there will
not be an unmitigable adverse impact on subsistence uses from L-DEO's's
proposed activities.
Endangered Species Act (ESA)
Section 7(a)(2) of the Endangered Species Act of 1973 (ESA: 16
U.S.C. 1531 et seq.) requires that each Federal agency insure that any
action it authorizes, funds, or carries out is not likely to jeopardize
the continued existence of any endangered or threatened species or
result in the destruction or adverse modification of designated
critical habitat. To ensure ESA compliance for the issuance of IHAs,
NMFS consults internally, in this case with the ESA Interagency
Cooperation Division, whenever we propose to authorize take for
endangered or threatened species.
NMFS is proposing to authorize take of blue whale, fin whale, gray
whale (WNP DPS), humpback whale (Mexico DPS and Western North Pacific
DPS), North Pacific right whale, sei whale, sperm whale, and Steller
sea lion (Western DPS), which are listed under the ESA.
The Permits and Conservation Division has requested initiation of
Section 7 consultation with the 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 seismic surveys in the Gulf of
Alaska in spring/early summer of 2019, provided the previously
mentioned mitigation, monitoring, and reporting requirements are
incorporated. A draft of the proposed IHA can be found at https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act.
Request for Public Comments
We request comment on our analyses, the proposed authorization, and
any other aspect of this Notice of Proposed IHA for L-DEO's proposed
survey. We also request comment on the potential for 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 our final decision on the request for MMPA authorization.
On a case-by-case basis, NMFS may issue a one-year IHA renewal with
an expedited public comment period (15 days) when (1) another year of
identical or nearly identical activities as described in the Specified
Activities section is planned or (2) the activities would not be
completed by the time the IHA expires and a second IHA would allow for
completion of the activities beyond that described in the Dates and
Duration section, provided all of the following conditions are met:
A request for renewal is received no later than 60 days
prior to expiration of the current IHA.
The request for renewal must include the following:
(1) An explanation that the activities to be conducted under the
proposed renewal 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
because only a subset of the initially analyzed activities remain to be
completed under the Renewal).
(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.
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: April 3, 2019.
Catherine Marzin,
Acting Director, Office of Protected Resources, National Marine
Fisheries Service.
[FR Doc. 2019-06886 Filed 4-8-19; 8:45 am]
BILLING CODE 3510-22-P