Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to Marine Geophysical Surveys in the Northeast Pacific Ocean
| Published date | 10 June 2019 |
| Citation | 84 FR 26940 |
| Record Number | 2019-12010 |
| Section | Notices |
| Court | National Oceanic And Atmospheric Administration |
Federal Register, Volume 84 Issue 111 (Monday, June 10, 2019)
[Federal Register Volume 84, Number 111 (Monday, June 10, 2019)]
[Notices]
[Pages 26940-26978]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2019-12010]
[[Page 26939]]
Vol. 84
Monday,
No. 111
June 10, 2019
Part IIDepartment of Commerce-----------------------------------------------------------------------National Oceanic and Atmospheric Administration-----------------------------------------------------------------------Takes of Marine Mammals Incidental to Specified Activities; Taking
Marine Mammals Incidental to Marine Geophysical Surveys in the
Northeast Pacific Ocean; Notice
Federal Register / Vol. 84 , No. 111 / Monday, June 10, 2019 /
Notices
[[Page 26940]]
-----------------------------------------------------------------------
DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
RIN 0648-XG948
Takes of Marine Mammals Incidental to Specified Activities;
Taking Marine Mammals Incidental to Marine Geophysical Surveys in the
Northeast Pacific Ocean
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.
-----------------------------------------------------------------------
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
northeast Pacific Ocean. 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 July 10,
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: Amy Fowler, 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/permit/incidental-take-authorizations-under-marine-mammal-protection-act. 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 NDAA (Pub. L. 108-136) removed the ``small numbers'' and
``specified geographical region'' limitations indicated above and
amended the definition of ``harassment'' as it applies to a ``military
readiness activity.'' 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 is preparing an Environmental Assessment (EA) to
consider the environmental impacts associated with the issuance of the
proposed IHA. NMFS' EA will be made available at https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act.
We will review all comments submitted in response to this notice
prior to concluding our NEPA process or making a final decision on the
IHA request.
Summary of Request
On December 21, 2018, NMFS received a request from L-DEO for an IHA
to take marine mammals incidental to a marine geophysical survey of the
Axial Seamount in the Northeast Pacific Ocean. The application was
deemed adequate and complete on May 3, 2019. L-DEO's request is for
take of a small number of 26 species of marine mammals by Level B
harassment and Level A harassment. Neither L-DEO nor NMFS expects
serious injury or mortality to result from this activity and,
therefore, an IHA is appropriate.
Description of Proposed Activity
Overview
Researchers from the University of Texas at Austin, University of
Nevada Reno, University of California San Diego, with funding from the
U.S. National Science Foundation (NSF), propose to conduct high-energy
seismic surveys from Research Vessel (R/V) Marcus G. Langseth
(Langseth) in the Northeast Pacific Ocean during summer 2019. The NSF-
owned Langseth is operated by Columbia University's L-DEO under an
existing Cooperative Agreement. The proposed two-dimensional (2-D) and
three-dimensional (3-D) seismic surveys would occur in International
Waters outside of the U.S. Exclusive Economic
[[Page 26941]]
Zone (EEZ). The 2-D survey would use a 36-airgun towed array with a
total discharge volume of ~6,600 cubic inches (in\3\); the 3-D survey
would employ an 18-airgun array with a discharge volume of ~3,300
in\3\.
The primary objectives of the surveys proposed by researchers from
the University of Texas at Austin Institute for Geophysics (UTIG), the
Nevada Seismological Laboratory at the University of Nevada Reno (UNR)
and Scripps Institution of Oceanography (SIO) at the University of
California San Diego, is to create a detailed 3-D image of the main and
satellite magma reservoirs that set the Axial volcano's framework,
image the 3-D fracture network and how they influence the magma bodies,
and to connect the subsurface observations to the surface features. The
main goal of the seismic program is to explore linkages between complex
magma chamber structure, caldera dynamics, fluid pathways, and
hydrothermal venting. Seismic data acquired during the proposed study
could be used to evaluate earthquake, tsunami, and submarine landslide
hazards.
Dates and Duration
The proposed surveys would be expected to last for 33 days,
including approximately 19 days of seismic operations (approximately 16
days for the 3-D survey and three days for the 2-D survey), seven days
of equipment deployment/retrieval, three days of operational
contingency time (e.g., infill, weather delays, etc.), two days for
turns (no airguns firing) during the 3-D survey, and roughly two days
of transit. R/V Langseth would leave out of and return to port in
Astoria, OR, during summer (July/August) 2019.
Specific Geographic Region
The proposed surveys would occur within ~45.5-46.5[deg] N, ~129.5-
130.5[deg] W. Representative survey tracklines are shown in Figure 1.
Some deviation in actual track lines, including the order of survey
operations, could be necessary for reasons such as science drivers,
poor data quality, inclement weather, or mechanical issues with the
research vessel and/or equipment. Thus, the tracklines could occur
anywhere within the coordinates noted above. The proposed surveys would
be conducted in International Waters outside the U.S. EEZ. The surveys
would occur in water depths ranging from 1,400 to 2,800 meters (m). The
proposed survey area is approximately 423 kilometers (km) (229 miles
(mi)) from shore at its closest point.
[GRAPHIC] [TIFF OMITTED] TN10JN19.000
[[Page 26942]]
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, R/V Langseth, which is owned by NSF and operated on its behalf
by L-DEO.
R/V Langseth would first deploy four 6-km streamers and 18 airguns
to conduct the 3-D multichannel seismic survey to examine the Axial
volcano and associated rift axes within an approximate 17 x 40 km area.
The 3-D survey would consist of a racetrack formation with 57 40-km
long lines and a turning diameter of 8.5 km (Figure 1); no airguns
would be firing during turns. The survey speed would be ~4.5 knots (kn)
(8.3 km/hour) for the 3-D survey. The airgun array and streamers would
then be recovered, and one 15-km streamer would be deployed along with
36 airguns to acquire eight ~26-km-long source-receiver offset 2-D
reflection profiles that would look at deep-seated structure of magma
delivery. During the 2-D survey, the airguns would be firing during
turns to the next line, and the survey speed would be ~4.2 kn (7.8 km/
hour).
The receiving system would consist of hydrophone streamers and up
to eight ocean bottom seismometers (OBSs). The OBSs are long-term
broadband instruments that would be left out for ~1 year and recovered
by another vessel. They have a height and diameter of ~1 m, with an 80
kg anchor. To retrieve OBSs, an acoustic release transponder (pinger)
is used to interrogate the instrument at a frequency of 8-11 kHz, and a
response is received at a frequency of 11.5-13 kHz. The burn-wire
release assembly is then activated, and the instrument is released to
float to the surface from the anchor which is not retrieved. Four 6-km
long hydrophone streamers would be used during 3-D data acquisition and
one 15-km long streamer would be employed for 2-D data acquisition. As
the airguns are towed along the survey lines, the hydrophone
streamer(s) would transfer the data to the on-board processing system,
and the OBSs would receive and store the returning acoustic signals
internally for later analysis.
A total of ~3,760 km of transect lines would be surveyed in the
Northeast Pacific Ocean: ~3,196 km during the 3-D survey (including run
ins and run outs) and 564 km during the 2-D survey. 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.
In addition to the operations of the airgun array, a multibeam
echosounder (MBES), a sub-bottom profiler (SBP), and an Acoustic
Doppler Current Profiler (ADCP) would be operated from R/V Langseth
continuously during the seismic surveys, but not during transit to and
from the survey area. 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.
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 (SARs; https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments) and more general information about these species
(e.g., physical and behavioral descriptions) may be found on NMFS's
website (https://www.fisheries.noaa.gov/find-species).
Table 1 lists all species with expected potential for occurrence in
the survey area and summarizes information related to the population or
stock, including regulatory status under the MMPA and ESA and potential
biological removal (PBR), where known. For taxonomy, we follow
Committee on Taxonomy (2016). 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.
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, this geographic area may extend
beyond U.S. waters. All managed stocks in this region are assessed in
NMFS's U.S. Pacific and Alaska SARs (Caretta et al., 2018; Muto 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 (Caretta et
al., 2018; Muto 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).
Table 1--Marine Mammals That Could Occur in the Survey Area
--------------------------------------------------------------------------------------------------------------------------------------------------------
ESA/ MMPA Stock abundance
status; (CV, Nmin, most
Common name Scientific name Stock strategic (Y/N) recent abundance PBR Annual M/SI \3\
\1\ survey) \2\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Order Cetartiodactyla--Cetacea--Superfamily Mysticeti (baleen whales)
--------------------------------------------------------------------------------------------------------------------------------------------------------
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............. Unknown
Pacific. 2016).
Family Balaenidae:
North Pacific right whale.... Eubalaena japonica.. Eastern North E/D; Y 31 (0.226, 26, 0.05............. 0
Pacific. 2015).
[[Page 26943]]
Family Balaenopteridae
(rorquals):
Humpback whale............... Megaptera California/Oregon/ -/-; Y 1,918 (0.03, 1,876, 11............... >9.2
novaeangliae. Washington. 2014).
Minke whale.................. Balaenoptera California/Oregon/ -/-; N 636 (0.72, 369, 3.5.............. >1.3
acutorostrata. Washington. 2014).
Sei whale.................... Balaenoptera Eastern North E/D; Y 519 (0.4, 374, 0.75............. 0
borealis. Pacific. 2014).
Fin whale.................... Balaenoptera California/Oregon/ E/D; Y 9,029 (0.12, 8,127, 81............... >2.0
physalus. Washington. 2014).
Blue whale................... Balaenoptera Eastern North E/D; Y 1,647 (0.07, 1,551, 2.3.............. >0.2
musculus. Pacific. 2011).
--------------------------------------------------------------------------------------------------------------------------------------------------------
Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Physeteridae:
Sperm whale.................. Physeter California/Oregon/ E/D; Y 1,967 (0.57, 1,270, 2.5.............. 0.9
macrocephalus. Washington. 2014).
Family Kogiidae:
Pygmy sperm whale............ Kogia breviceps..... California/Oregon/ -/-; N 4,111 (1.12, 1,924, 19............... 0
Washington. 2014).
Dwarf sperm whale............ Kogia sima.......... California/Oregon/ -/-; N Unknown (Unknown, Undetermined..... 0
Washington. Unknown, 2014).
Family Ziphiidae (beaked whales):
Cuvier's beaked whale........ Ziphius cavirostris. California/Oregon/ -/-; N 3,274 (0.67, 2,059, 21............... 1.6
Washington offshore. 2014).
Striped dolphin.............. Stenella California/Oregon/ -/-; N 29,211 (0.2, 238.............. > 0.8
coeruleoalba. Washington. 24,782, 2014).
Short-beaked common dolphin.. Delphinus delphis... California/Oregon/ -/-; N 969,861 (0.17, 8,393............ >40
Washington. 839,325, 2014).
Pacific white-sided dolphin.. Lagenorhynchus California/Oregon/ -/-; N 26,814 (0.28, 191.............. 7.5
obliquidens. Washington. 21,195, 2014).
Northern right whale dolphin. Lissodelphis California/Oregon/ -/-; N 26,556 (0.44, 179.............. 3.8
borealis. Washington. 18,608, 2014).
Risso's dolphin.............. Grampus griseus..... California/Oregon/ -/-; N 6,336 (0.32, 4,817, 46............... >3.7
Washington. 2014).
False killer whale........... Pseudorca crassidens Hawaii Pelagic...... -/-; N 1,540 (0.66, 928, 9.3.............. 7.6
2010).
Killer whale................. Orcinus orca........ Offshore............ -/-; N 240 (0.49, 162, 1.6.............. 0
Southern Resident... E/D; Y 2014). 0.14............. 0
Northern Resident... -/-; N 83 (N/A, 83, 2016). 1.96............. 0
West Coast Transient -/-; N 261 (N/A, 261, 2.4.............. 0
2011).
243 (N/A, 243,
2009).
Short-finned pilot whale..... Globicephala California/Oregon/ -/-; N 836 (0.79, 466, 4.5.............. 1.2
macrorhynchus. Washington. 2014).
Family Phocoenidae (porpoises):
Harbor porpoise.............. Phocoena phocoena... Northern Oregon/ -/-; N 21,487 (0.44, 151.............. >3.0
Washington Coast. 15,123, 2011).
Dall's porpoise.............. Phocoenoides dalli.. California/Oregon/ -/-; N 25,750 (0.45, 172.............. 0.3
Washington. 17,954, 2014).
--------------------------------------------------------------------------------------------------------------------------------------------------------
Order Carnivora--Superfamily Pinnipedia
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Otariidae (eared seals and
sea lions):
Northern fur seal............ Callorhinus ursinus. Eastern Pacific..... -/D; Y 620,660 (0.2, 11,295........... 457
California.......... -/D; N 525,333, 2016). 451.............. 1.8
14,050 (N/A, 7,524,
2013).
California sea lion.......... Zalophus U.S................. -/-; N 257,606 (N/A, 14,011........... >197
californianus. 233,515, 2014).
Steller sea lion............. Eumetopias jubatus.. Eastern U.S......... -/-; N 41,638 (see SAR, 2,498............ 108
41,638, 2015).
Guadalupe fur seal........... Arctocephalus Mexico.............. T/D; Y 20,000 (N/A, 542.............. >3.2
townsendi. 15,830, 2010).
Family Phocidae (earless seals):
Harbor seal.................. Phoca vitulina...... Oregon/Washington -/-; N Unknown (Unknown, Undetermined..... 10.6
Coastal. Unknown, 1999).
[[Page 26944]]
Northern elephant seal....... Mirounga California Breeding. -/-; N 179,000 (N/A, 4,882............ 8.8
angustirostris. 81,368, 2010).
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Endangered Species Act (ESA) status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-) indicates that the species is not listed
under the ESA or designated as depleted under the MMPA. Under the MMPA, a strategic stock is one for which the level of direct human-caused mortality
exceeds PBR or which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed
under the ESA is automatically designated under the MMPA as depleted and as a strategic stock.
\2\ NMFS marine mammal stock assessment reports online at: www.nmfs.noaa.gov/pr/sars/. CV is coefficient of variation; Nmin is the minimum estimate of
stock abundance. In some cases, CV is not applicable.
\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). Annual M/SI often cannot be determined precisely and is in some cases presented as a minimum value or range. A CV
associated with estimated mortality due to commercial fisheries is presented in some cases.
Note: Italicized species 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. However, the temporal and/or spatial
occurrence of gray whales, Southern Resident and Northern Resident
killer whales, harbor porpoise, harbor seal, California sea lion, and
Steller sea lion is such that take is not expected to occur, and they
are not discussed further beyond the explanation provided here. These
species are found in the eastern North Pacific, but are generally found
in coastal waters and are not expected to occur offshore in the survey
area.
Humpback Whale
The humpback whale is found throughout all of the oceans of the
world (Clapham 2009). The worldwide population of humpbacks is divided
into northern and southern ocean populations, but genetic analyses
suggest some gene flow (either past or present) between the North and
South Pacific (e.g., Baker et al., 1993; Caballero et al., 2001).
Geographical overlap of these populations has been documented only off
Central America (Acevedo and Smultea 1995; Rasmussen et al., 2004,
2007). Although considered to be mainly a coastal species, humpback
whales often traverse deep pelagic areas while migrating (Clapham and
Mattila 1990; Norris et al., 1999; Calambokidis et al., 2001).
Humpback whales migrate between summer feeding grounds in high
latitudes and winter calving and breeding grounds in tropical waters
(Clapham and Mead 1999). North Pacific humpback whales summer in
feeding grounds along the Pacific Rim and in the Bering and Okhotsk
seas (Pike and MacAskie 1969; Rice 1978; Winn and Reichley 1985;
Calambokidis et al., 2000, 2001, 2008). 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; Bettridge et al., 2015). These breeding areas have been
designated as DPSs, but feeding areas have no DPS status (Bettridge et
al., 2015; NMFS 2016b). Individuals encountered in the proposed survey
area most likely would come from the Central America and Mexico
distinct population segments (DPSs), although some individuals from the
Hawaii DPS may also feed in these waters. There is a low level of
interchange of whales among the main wintering areas and among feeding
areas (e.g., Darling and Cerchio 1993; Salden et al., 1999;
Calambokidis et al., 2001, 2008).
The humpback whale is the most common species of large cetacean
reported off the coasts of Oregon and Washington from May to November
(Green et al., 1992; Calambokidis et al., 2000, 2004). The highest
numbers have been reported off Oregon during May and June and off
Washington during July-September. However, off Oregon and Washington,
humpbacks occur primarily over the continental shelf and slope during
the summer, with few reported in offshore pelagic waters (Green et al.,
1992; Calambokidis et al., 2004, 2015; Becker et al., 2012; Menza et
al., 2016). Biologically important areas (BIAs) for feeding humpback
whales along the coasts of Oregon and Washington, which have been
designated from May to November, are all within ~80 km offshore
(Calambokidis et al., 2015).
Minke Whale
The minke whale has a cosmopolitan distribution that spans from
tropical to polar regions in both hemispheres (Jefferson et al., 2015).
In the Northern Hemisphere, the minke whale is usually seen in coastal
areas, but can also be seen in pelagic waters during its northward
migration in spring and summer and southward migration in autumn
(Stewart and Leatherwood 1985). In the North Pacific, the summer range
of the minke whale extends to the Chukchi Sea; in the winter, the
whales move farther south to within 2[deg] of the Equator (Perrin and
Brownell 2009).
The International Whaling Commission (IWC) recognizes three stocks
of minke whales 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). Minke whales are relatively common in
the Bering and Chukchi seas and in the Gulf of Alaska, but are not
considered abundant in any other part of the eastern Pacific
(Brueggeman et al., 1990). In the far north, minke whales are thought
to be migratory, but they are believed to be year-round residents in
coastal waters off the U.S. West Coast (Dorsey et al., 1990).
Sei Whale
The distribution of the sei whale is not well known, but it is
found in all oceans and appears to prefer mid-latitude temperate waters
(Jefferson et al., 2015). The sei whale is pelagic and generally not
found in coastal waters (Jefferson et al., 2015). It is found 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., 1999a). Sei whales migrate from temperate zones occupied
in winter to higher latitudes in the summer, where most feeding takes
place (Gambell 1985a). During summer in the North Pacific, the sei
whale can be found from the Bering Sea to the Gulf of Alaska and down
to southern
[[Page 26945]]
California, as well as in the western Pacific from Japan to Korea. Its
winter distribution is concentrated at ~20[deg] N (Rice 1998).
Fin Whale
The fin whale is widely distributed in all the world's oceans
(Gambell 1985b), but typically occurs in temperate and polar regions
from 20-70[deg] north and south of the Equator (Perry et al., 1999b).
Northern and southern fin whale populations are distinct and are
sometimes recognized as different subspecies (Aguilar 2009). Fin whales
occur in coastal, shelf, and oceanic waters. Sergeant (1977) suggested
that fin whales tend to follow steep slope contours, either because
they detect them readily or because biological productivity is high
along steep contours because of tidal mixing and perhaps current
mixing. Stafford et al., (2009) noted that sea-surface temperature is a
good predictor variable for fin whale call detections in the North
Pacific.
Fin whales appear to have complex seasonal movements and are
seasonal migrants; they mate and calve in temperate waters during the
winter and migrate to feed at northern latitudes during the summer
(Gambell 1985b). The North Pacific population summers from the Chukchi
Sea to California and winters from California southwards (Gambell
1985b). Aggregations of fin whales are found year-round off southern
and central California (Dohl et al., 1980, 1983; Forney et al., 1995;
Barlow 1997) and in the summer off Oregon (Green et al., 1992; Edwards
et al., 2015). Vocalizations from fin whales have also been detected
year-round off northern California, Oregon, and Washington (Moore et
al., 1998, 2006; Watkins et al., 2000a, b; Stafford et al., 2007, 2009;
Edwards et al., 2015).
Blue Whale
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). Although it has been suggested that there are at least
five subpopulations of blue whales in the North Pacific (NMFS 1998),
analysis of blue whale calls monitored from the U.S. Navy Sound
Surveillance System (SOSUS) and other offshore hydrophones (see
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 western North Pacific (Sears and Perrin 2009).
Broad-scale acoustic monitoring indicates that blue whales occurring in
the northeast Pacific during summer and fall may winter in the eastern
tropical Pacific (Stafford et al., 1999, 2001).
The distribution of the species, at least during times of the year
when feeding is a major activity, occurs in areas that provide large
seasonal concentrations of euphausiids (Yochem and Leatherwood 1985).
The eastern North Pacific stock feeds in California waters from June-
November (Calambokidis et al., 1990; Mate et al., 1999). There are nine
BIAs for feeding blue whales off the coast of California (Calambokidis
et al., 2015), and core areas have also been identified there (Irvine
et al., 2014). Blue whales have been detected acoustically off Oregon
(McDonald et al., 1995; Stafford et al., 1998; Von Saunder and Barlow
1999), but sightings are uncommon (Carretta et al., 2018). Densities
along the U.S. West Coast, including Oregon, were predicted to be
highest in shelf waters, with lower densities in deeper offshore areas
(Becker et al., 2012; Calambokidis et al., 2015). Buchanan et al.,
(2001) considered blue whales to be rare off Oregon and Washington.
However, based on the absolute dynamic topography of the region, blue
whales could occur in relatively high densities off Oregon during July-
December (Pardo et al., 2015).
Sperm Whale
The sperm whale is the largest of the toothed whales, with an
extensive worldwide distribution (Rice 1989). Sperm whale distribution
is linked to social structure: Mixed groups of adult females and
juvenile animals of both sexes generally occur in tropical and
subtropical waters, whereas adult males are commonly found alone or in
same-sex aggregations, often occurring in higher latitudes outside the
breeding season (Best 1979; Watkins and Moore 1982; Arnbom and
Whitehead 1989; Whitehead and Waters 1990). Males can migrate north in
the summer to feed in the Gulf of Alaska, Bering Sea, and waters around
the Aleutian Islands (Kasuya and Miyashita 1988). Mature male sperm
whales migrate to warmer waters to breed when they are in their late
twenties (Best 1979).
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; Whitehead 2009). They
are often found far from shore, but can be found closer to oceanic
islands that rise steeply from deep ocean waters (Whitehead 2009).
Adult males can occur in water depths 1,000 m
(Heyning 1989). It is mostly known from strandings and strands more
commonly than any other beaked whale (Heyning 1989). Its inconspicuous
blows, deep-diving behavior, and tendency to avoid vessels all help to
explain the infrequent sightings (Barlow and Gisiner 2006). The
population in the California Current Large Marine Ecosystem seems to be
declining (Moore and Barlow 2013).
MacLeod et al., (2006) reported numerous sightings and strandings
along the Pacific coast of the U.S. Cuvier's beaked whale is the most
common beaked whale off the U.S. West Coast (Barlow 2010), and it is
the beaked whale species that has stranded most frequently on the
coasts of Oregon and Washington. From 1942-2010, there were 23 reported
Cuvier's beaked whale strandings in Oregon and Washington (Moore and
Barlow 2013). Most (75 percent) Cuvier's beaked whale strandings
reported occurred in Oregon (Norman et al., 2004).
Blainville's Beaked Whale
Blainville's beaked whale is found in tropical and warm temperate
waters of all oceans (Pitman 2009). It has the widest distribution
throughout the world of all mesoplodont species and appears to be
relatively common (Pitman 2009). Like other beaked whales, Blainville's
beaked whale is generally found in waters 200-1400 m deep (Gannier
2000; Jefferson et al., 2015). Occasional occurrences in cooler,
higher-latitude waters are presumably related to warm-water incursions
(Reeves et al., 2002). MacLeod et al., (2006) reported stranding and
sighting records in the eastern Pacific ranging from 37.3[deg] N to
41.5[deg] S. However, none of the 36 beaked whale stranding records in
Oregon and Washington during 1930-2002 included Blainville's beaked
whale (Norman et al., 2004). One Blainville's beaked whale was found
stranded (dead) on the Washington coast in November 2016 (COASST 2016).
Stejneger's Beaked Whale
Stejneger's beaked whale occurs in subarctic and cool temperate
waters of the North Pacific Ocean (Mead 1989). In the eastern North
Pacific Ocean, it is distributed from Alaska to southern California
(Mead et al., 1982; Mead 1989). Most stranding records are from Alaskan
waters, and the Aleutian Islands appear to be its center of
distribution (MacLeod et al., 2006). After Cuvier's beaked whale,
Stejneger's beaked whale was the second most commonly stranded beaked
whale species in Oregon and Washington (Norman et al., 2004).
Hubb's Beaked Whale
Hubbs' beaked whale occurs in temperate waters of the North Pacific
(Mead 1989). Its distribution appears to be correlated with the deep
subarctic current (Mead et al., 1982). Numerous stranding records have
been reported for the U.S. West Coast (MacLeod et al., 2006). Most of
the records are from California, but it has been sighted as far north
as Prince Rupert, British Columbia (Mead 1989). Two strandings are
known from Washington/Oregon (Norman et al., 2004). Hubbs' beaked
whales are often killed in drift gillnets off California (Reeves et
al., 2002).
There are no sightings of Hubbs' beaked whales near the proposed
survey area in the OBIS database (OBIS 2018). There is one sighting of
an unidentified species of Mesoplodont whale near the survey area in
the OBIS database that was made in July 1996 during the SWFSC ORCAWALE
Marine Mammal Survey (OBIS 2018). During the 2016 SWFSC PASCAL study
using drifting acoustic recorders, detections were made of beaked whale
sounds presumed to be from Hubbs' beaked whales near the proposed
survey area during August (Griffiths et al., submitted manuscript cited
in Keating et al., 2018). In addition, at least two sightings just to
the south of the proposed survey area were reported in Carretta et al.,
(2018). This species seems to be less common in the proposed survey
area than some of the other beaked whales.
Baird's Beaked Whale
Baird's beaked whale has a fairly extensive range across the North
Pacific, with concentrations occurring in the Sea of Okhotsk and Bering
Sea (Rice 1998; Kasuya 2009). In the eastern Pacific, Baird's beaked
whale is reported to occur as far south as San Clemente Island,
California (Rice 1998; Kasuya 2009). Baird's beaked whales that occur
off the U.S. west coast are of the gray form, unlike some Berardius
individuals that are found in Alaska and Japan, which are of the black
form and thus could be a new species (Morin et al., 2017).
Bottlenose Dolphin
The bottlenose dolphin is distributed worldwide in coastal and
shelf waters of tropical and temperate oceans (Jefferson et al., 2015).
There are two distinct bottlenose dolphin types: A shallow water type,
mainly found in coastal waters, and a deep water type, mainly found in
oceanic waters (Duffield et al., 1983; Hoelzel et al., 1998; Walker et
al., 1999). Coastal common bottlenose dolphins exhibit a range of
movement patterns including seasonal migration, year-round residency,
and a combination of long-range movements and repeated local residency
(Wells and Scott 2009).
Short-Beaked Common Dolphin
The short-beaked common dolphin is found in tropical and warm
temperate oceans around the world (Perrin 2009). It ranges as far south
as 40[deg] S in the Pacific Ocean, is common in coastal waters 200-300
m deep and is also associated with prominent underwater topography,
such as seamounts (Evans 1994). Short-beaked common dolphins have been
sighted as far as 550 km from shore (Barlow et al., 1997).
The distribution of short-beaked common dolphins along the U.S.
West Coast is variable and likely related to oceanographic changes
(Heyning and Perrin 1994; Forney and Barlow 1998). It is the most
abundant cetacean off California; some sightings have been made off
Oregon, in offshore waters (Carretta et al., 2017). During surveys off
the west coast in 2014 and 2017, sightings were made as far north as
44[deg] N (Barlow 2016; SIO n.d.). Based on the absolute dynamic
topography of the region, short-beaked common dolphins could occur in
relatively high densities off Oregon during July-December (Pardo et
al., 2015). In contrast, habitat modeling predicted moderate densities
of common dolphins off the Columbia River mouth during summer, with
lower densities off southern Oregon (Becker et al., 2014).
Striped Dolphin
The striped dolphin has a cosmopolitan distribution in tropical to
warm temperate waters (Perrin et al., 1994) and is generally seen south
of 43[deg] N (Archer 2009). However, in the eastern North Pacific, its
distribution extends as far north as Washington (Jefferson et al.,
2015). The striped dolphin is typically found in waters outside the
continental shelf and is often associated with convergence zones and
areas of upwelling (Archer 2009). However, it has also been observed
approaching shore where there is deep
[[Page 26947]]
water close to the coast (Jefferson et al., 2015).
Pacific White-Sided Dolphin
The Pacific white-sided dolphin is found in cool temperate waters
of the North Pacific from the southern Gulf of California to Alaska.
Across the North Pacific, it appears to have a relatively narrow
distribution between 38[deg] N and 47[deg] N (Brownell et al., 1999).
In the eastern North Pacific Ocean, including waters off Oregon, the
Pacific white-sided dolphin is one of the most common cetacean species,
occurring primarily in shelf and slope waters (Green et al., 1993;
Barlow 2003, 2010). It is known to occur close to shore in certain
regions, including (seasonally) southern California (Brownell et al.,
1999).
Results of aerial and shipboard surveys strongly suggest seasonal
north-south movements of the species between California and Oregon/
Washington; the movements apparently are related to oceanographic
influences, particularly water temperature (Green et al., 1993; Forney
and Barlow 1998; Buchanan et al., 2001). During winter, this species is
most abundant in California slope and offshore areas; as northern
waters begin to warm in the spring, it appears to move north to slope
and offshore waters off Oregon/Washington (Green et al., 1992, 1993;
Forney 1994; Forney et al., 1995; Buchanan et al., 2001; Barlow 2003).
The highest encounter rates off Oregon and Washington have been
reported during March-May in slope and offshore waters (Green et al.,
1992). Similarly, Becker et al., (2014) predicted relatively high
densities off southern Oregon in shelf and slope waters.
Based on year-round aerial surveys off Oregon/Washington, the
Pacific white-sided dolphin was the most abundant cetacean species,
with nearly all (97 percent) sightings occurring in May (Green et al.,
1992, 1993). Barlow (2003) also found that the Pacific white-sided
dolphin was one of the most abundant marine mammal species off Oregon/
Washington during 1996 and 2001 ship surveys, and it was the second
most abundant species reported during 2008 surveys (Barlow 2010). Adams
et al., (2014) reported numerous offshore sightings off Oregon during
summer, fall, and winter surveys in 2011 and 2012. Based on surveys
conducted during 2014, the abundance was estimated at 20,711 for
Oregon/Washington (Barlow 2016).
Northern Right Whale Dolphin
The northern right whale dolphin is found in cool temperate and
sub-arctic waters of the North Pacific, from the Gulf of Alaska to near
northern Baja California, ranging from 30[deg] N to 50[deg] N (Reeves
et al., 2002). In the eastern North Pacific Ocean, including waters off
Oregon, the northern right whale dolphin is one of the most common
marine mammal species, occurring primarily in shelf and slope waters
~100 to >2,000 m deep (Green et al., 1993; Barlow 2003). The northern
right whale dolphin comes closer to shore where there is deep water,
such as over submarine canyons (Reeves et al., 2002).
Aerial and shipboard surveys suggest seasonal inshore-offshore and
north-south movements in the eastern North Pacific Ocean between
California and Oregon/Washington; the movements are believed to be
related to oceanographic influences, particularly water temperature and
presumably prey distribution and availability (Green et al., 1993;
Forney and Barlow 1998; Buchanan et al., 2001). Green et al., (1992,
1993) found that northern right whale dolphins were most abundant off
Oregon/Washington during fall, less abundant during spring and summer,
and absent during winter, when this species presumably moves south to
warmer California waters (Green et al., 1992, 1993; Forney 1994; Forney
et al., 1995; Buchanan et al., 2001; Barlow 2003). Considerable
interannual variations in abundance also have been found.
Becker et al., (2014) predicted relatively high densities off
southern Oregon, and moderate densities off northern Oregon and
Washington. Based on year-round aerial surveys off Oregon/Washington,
the northern right whale dolphin was the third most abundant cetacean
species, concentrated in slope waters but also occurring in water out
to ~550 km offshore (Green et al., 1992, 1993). Barlow (2003, 2010)
also found that the northern right whale dolphin was one of the most
abundant marine mammal species off Oregon/Washington during 1996, 2001,
2005, and 2008 ship surveys. Offshore sightings were made in the waters
of Oregon during summer, fall, and winter surveys in 2011 and 2012
(Adams et al., 2014).
Risso's Dolphin
Risso's dolphin is distributed worldwide in temperate and tropical
oceans (Baird 2009), although it shows a preference for mid-temperate
waters of the shelf and slope between 30[deg] and 45[deg] (Jefferson et
al., 2014). Although it is known to occur in coastal and oceanic
habitats (Jefferson et al., 2014), it appears to prefer steep sections
of the continental shelf, 400-1,000 m deep (Baird 2009), and is known
to frequent seamounts and escarpments (Kruse et al., 1999). Off the
U.S. West Coast, 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).
The distribution and abundance of Risso's dolphins are highly
variable from California to Washington, presumably in response to
changing oceanographic conditions on both annual and seasonal time
scales (Forney and Barlow 1998; Buchanan et al., 2001). The highest
densities were predicted along the coasts of Washington, Oregon, and
central and southern California (Becker et al., 2012). Off Oregon and
Washington, Risso's dolphins are most abundant over continental slope
and shelf waters during spring and summer, less so during fall, and
rare during winter (Green et al., 1992, 1993). Green et al., (1992,
1993) reported most Risso's dolphin groups off Oregon between ~45 and
47[deg] N. Several sightings were made off southern Oregon during
surveys in 1991-2014 (Carretta et al., 2017). Sightings during ship
surveys in summer/fall 2008 were mostly between ~30 and 38[deg] N; none
were reported in Oregon/Washington (Barlow 2010). Based on 2014 survey
data, the abundance for Oregon/Washington was estimated at 430 (Barlow
2016).
False Killer Whale
The false killer whale is found in all tropical and warmer
temperate oceans, especially in deep, offshore waters (Odell and
McClune 1999). However, it is also known to occur in nearshore areas
(e.g., Stacey and Baird 1991). In the eastern North Pacific, it has
been reported only rarely north of Baja California (Leatherwood et al.,
1982, 1987; Mangels and Gerrodette 1994); however, the waters off the
U.S. West Coast all the way north to Alaska are considered part of its
secondary range (Jefferson et al., 2015). Its occurrence in Washington/
Oregon is associated with warm-water incursions (Buchanan et al.,
2001). One pod of false killer whales occurred in Puget Sound for
several months during the 1990s (USN 2015). Two were reported stranded
along the Washington coast during 1930-2002, both in El Ni[ntilde]o
years (Norman et al., 2004). One sighting was made off southern
California during 2014 (Barlow 2016).
[[Page 26948]]
Killer Whale
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). Currently, there are eight
killer whale stocks recognized in the U.S. Pacific: (1) Alaska
Residents, occurring from southeast Alaska to the Aleutians and Bering
Sea; (2) Northern Residents, from BC through parts of southeast Alaska;
(3) Southern Residents, mainly in inland waters of Washington State and
southern BC; (4) Gulf of Alaska, Aleutians, and Bering Sea Transients,
from Prince William Sound (PWS) through to the Aleutians and Bering
Sea; (5) AT1 Transients, from PWS through the Kenai Fjords; (6) West
Coast Transients, from California through southeast Alaska; (7)
Offshore, from California through Alaska; and (8) Hawaiian (Carretta et
al., 2018). Individuals from the Offshore and West Coast Transient
stocks could be encountered in the proposed project area.
Green et al. (1992) noted that most groups seen during their
surveys off Oregon and Washington were likely transients; during those
surveys, killer whales were sighted only in shelf waters. Killer whales
were sighted off Washington in July and September 2012 (Adams et al.,
2014). Two of 17 killer whales that stranded in Oregon were confirmed
as transient (Stevens et al., 1989 in Norman et al., 2004).
Short-Finned Pilot Whale
The short-finned pilot whale is found in tropical, subtropical, and
warm temperate waters (Olson 2009); it is seen as far south as ~40[deg]
S and as far north as ~50[deg] N (Jefferson et al., 2015). Pilot whales
are generally nomadic, but may be resident in certain locations,
including California and Hawaii (Olson 2009). Short-finned pilot whales
were common off southern California (Dohl et al., 1980) until an El
Ni[ntilde]o event occurred in 1982-1983 (Carretta et al., 2017).
Dall's Porpoise
Dall's porpoise is found in temperate to subantarctic waters of the
North Pacific and adjacent seas (Jefferson et al., 2015). 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). It
is probably the most abundant small cetacean in the North Pacific
Ocean, and its abundance changes seasonally, likely in relation to
water temperature (Becker 2007).
Off Oregon and Washington, Dall's porpoise is widely distributed
over shelf and slope waters, with concentrations near shelf edges, but
is also commonly sighted in pelagic offshore waters (Morejohn 1979;
Green et al., 1992; Becker et al., 2014; Carretta et al., 2018).
Combined results of various surveys out to ~550 km offshore indicate
that the distribution and abundance of Dall's porpoise varies between
seasons and years. North-south movements are believed to occur between
Oregon/Washington and California in response to changing oceanographic
conditions, particularly temperature and distribution and abundance of
prey (Green et al., 1992, 1993; Mangels and Gerrodette 1994; Barlow
1995; Forney and Barlow 1998; Buchanan et al., 2001). Becker et al.,
(2014) predicted high densities off southern Oregon throughout the
year, with moderate densities to the north. According to predictive
density distribution maps, the highest densities off southern
Washington and Oregon occur along the 500-m isobath (Menza et al.,
2016).
Encounter rates reported by Green et al., (1992) during aerial
surveys off Oregon/Washington were highest in fall, lowest during
winter, and intermediate during spring and summer. Encounter rates
during the summer were similarly high in slope and shelf waters, and
somewhat lower in offshore waters (Green et al., 1992). Dall's porpoise
was the most abundant species sighted off Oregon/Washington during
1996, 2001, 2005, and 2008 ship surveys up to ~550 km from shore
(Barlow 2003, 2010).
Northern Fur Seal
The northern fur seal is endemic to the North Pacific Ocean and
occurs from southern California to the Bering Sea, Sea of Okhotsk, and
Sea of Japan (Jefferson et al., 2015). The worldwide population of
northern fur seals has declined substantially from 1.8 million animals
in the 1950s (Muto et al., 2018). They were subjected to large-scale
harvests on the Pribilof Islands to supply a lucrative fur trade. Two
stocks are recognized in U.S. waters: The Eastern North Pacific and the
California stocks. The Eastern Pacific stock ranges from southern
California during winter to the Pribilof Islands and Bogoslof Island in
the Bering Sea during summer (Carretta et al., 2018; Muto et al.,
2018). Abundance of the Eastern Pacific Stock has been decreasing at
the Pribilof Islands since the 1940s and increasing on Bogoslof Island.
Most northern fur seals are highly migratory. During the breeding
season, most of the world's population of northern fur seals occurs on
the Pribilof and Bogoslof islands (NMFS 2007). The main breeding season
is in July (Gentry 2009). Adult males usually occur onshore from May to
August, though some may be present until November; females are usually
found ashore from June to November (Muto et al., 2018). Nearly all fur
seals from the Pribilof Island rookeries are foraging at sea from fall
through late spring. In November, females and pups leave the Pribilof
Islands and migrate through the Gulf of Alaska to feeding areas
primarily off the coasts of BC, Washington, Oregon, and California
before migrating north again to the rookeries in spring (Ream et al.,
2005; Pelland et al., 2014). Immature seals can remain in southern
foraging areas year-round until they are old enough to mate (NMFS
2007). Adult males migrate only as far south as the Gulf of Alaska or
to the west off the Kuril Islands (Kajimura 1984). Pups from the
California stock also migrate to Washington, Oregon, and northern
California after weaning (Lea et al., 2009).
The northern fur seals spends ~90 percent of its time at sea,
typically in areas of upwelling along the continental slopes and over
seamounts (Gentry 1981). The remainder of its life is spent on or near
rookery islands or haulouts. While at sea, northern fur seals usually
occur singly or in pairs, although larger groups can form in waters
rich with prey (Antonelis and Fiscus 1980; Gentry 1981). Northern fur
seals dive to relatively shallow depths to feed: 100-200 m for females,
and 2,000 m) off central and southern Oregon (Bonnell et al.,
1992). The waters off Washington are a known foraging area for adult
females, and concentrations of fur seals were also reported to occur
near Cape Blanco, Oregon, at ~42.8[deg] N (Pelland et al., 2014).
Tagged adult fur seals were tracked from the Pribilof Islands to the
waters off Washington/Oregon/California, with recorded movement
[[Page 26949]]
throughout the proposed project area (Pelland et al., 2014).
Guadalupe Fur Seal
Guadalupe fur seals were once plentiful on the California coast,
ranging from the Gulf of the Farallones near San Francisco, to the
Revillagigedo Islands, Mexico (Aurioles-Gamboa et al., 1999), but they
were over-harvested in the 19th century to near extinction. After being
protected, the population grew slowly; mature individuals of the
species were observed occasionally in the Southern California Bight
starting in the 1960s (Stewart et al., 1993), and, in 1997, a female
and pup were observed on San Miguel Island (Melin & DeLong, 1999).
Since then, a small group has persisted in that area (Aurioles-Gamboa
et al., 2010).
The distribution of Guadalupe fur seals and occurrence in the
survey area is dependent on life stage and season. During the breeding
season, June through August, adult males are expected to be on shore on
Guadalupe Island and at smaller rookeries in the San Benito archipelago
(Carretta et al., 2017b; Norris, 2017b). No satellite telemetry data
are available for adult males; however, following the breeding season
most adult males are expected to move north of breeding grounds to
forage.
From 2015 through 2017, 26 stranded and rehabilitated fur seals
between the ages of 11 and 15 months were released with satellite tags
in central California. These animals frequently migrated north of Point
Cabrillo and several moved into waters as far north as British
Columbia, Canada. However, it is unclear if the migratory patterns of
rehabilitated and released fur seals are representative of the free-
ranging population migrating north from Guadalupe Island. For example,
the rehabilitated fur seals remained closer to shore than the free-
ranging fur seals as they migrated north (Norris, 2017b).
The satellite telemetry data indicate that Guadalupe fur seals more
than two years old are likely uncommon in the survey area, but a
majority of fur seals under two years old may migrate into the survey
area and may be present throughout the year (Norris, 2017b). Lambourn
et al. (2012) described an unusual mortality event during which 29
Guadalupe fur seals were reported stranded throughout the Pacific
Northwest from 2007 to 2009. The strandings involved one live adult
female and 28 dead yearlings of both sexes. The stranding data support
the more recent telemetry data indicating that fur seals less than 2
years of age are more likely to occur in the survey area than older fur
seals.
Northern Elephant Seal
The northern elephant seal breeds in California and Baja
California, primarily on offshore islands, from Cedros off the west
coast of Baja California, north to the Farallons in Central California
(Stewart et al., 1994). Pupping has also been observed at Shell Island
(~43.3[deg] N) off southern Oregon, suggesting a range expansion
(Bonnell et al., 1992; Hodder et al., 1998).
Adult elephant seals engage in two long northward migrations per
year, one following the breeding season, and another following the
annual molt (Stewart and DeLong 1995). Between the two foraging
periods, they return to land to molt, with females returning earlier
than males (March-April vs. July-August). After the molt, adults then
return to their northern feeding areas until the next winter breeding
season. Breeding occurs from December to March (Stewart and Huber
1993). Females arrive in late December or January and give birth within
~1 week of their arrival. Pups are weaned after just 27 days and are
abandoned by their mothers. Juvenile elephant seals typically leave the
rookeries in April or May and head north, traveling an average of 900-
1,000 km. Hindell (2009) noted that traveling likely takes place at
depths >200 m. Most elephant seals return to their natal rookeries when
they start breeding (Huber et al., 1991).
When not at their breeding rookeries, adults feed at sea far from
the rookeries. Males may feed as far north as the eastern Aleutian
Islands and the Gulf of Alaska, whereas females feed south of 45[deg] N
(Le Boeuf et al., 1993; Stewart and Huber 1993). Adult male elephant
seals migrate north via the California current to the Gulf of Alaska
during foraging trips, and could potentially be passing through the
area off Washington in May and August (migrating to and from molting
periods) and November and February (migrating to and from breeding
periods), but likely their presence there is transient and short-lived.
Adult females and juveniles forage in the California current off
California to BC (Le Boeuf et al. 1986, 1993, 2000). Bonnell et al.,
(1992) reported that northern elephant seals were distributed equally
in shelf, slope, and offshore waters during surveys conducted off
Oregon and Washington, as far as 150 km from shore, in waters >2,000 m
deep. Telemetry data indicate that they range much farther offshore
than that (Stewart and DeLong 1995).
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 whales, 150 Hz to 160 kHz.
beaked whales, bottlenose whales).
High-frequency (HF) cetaceans (true porpoises, Kogia, 275 Hz to 160 kHz.
river dolphins, cephalorhynchid, Lagenorhynchus
cruciger & L. australis).
[[Page 26950]]
Phocid pinnipeds (PW) (underwater) (true seals)........ 50 Hz to 86 kHz.
Otariid pinnipeds (OW) (underwater) (sea lions and fur 60 Hz to 39 kHz.
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.
26 marine mammal species (23 cetacean and three pinniped (two otariid
and one phocid) species) have the reasonable potential to co-occur with
the proposed survey activities. Please refer to Table 1. Of the
cetacean species that may be present, five are classified as low-
frequency cetaceans (i.e., all mysticete species), 15 are classified as
mid-frequency cetaceans (i.e., all delphinid and ziphiid species and
the sperm whale), and three 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]Pa2 - 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):
Wind and waves: The complex interactions between wind and
water
[[Page 26951]]
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.
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 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.
[[Page 26952]]
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. 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
[[Page 26953]]
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 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,
[[Page 26954]]
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]Pa2-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.
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
[[Page 26955]]
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, 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),
[[Page 26956]]
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 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,
[[Page 26957]]
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 4.1 kn (7.6 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% 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.
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
[[Page 26958]]
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 in\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 (~19 days) at
two locations and would occur over a very small area relative to the
area available as marine mammal habitat in the northeast Pacific Ocean
near the Axial Seamount. We believe any impacts to marine mammals due
to adverse effects 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-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 these 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
[[Page 26959]]
stock in the wild (Level A harassment); or (ii) has the potential to
disturb a marine mammal or marine mammal stock in the wild by causing
disruption of behavioral patterns, including, but not limited to,
migration, breathing, nursing, breeding, feeding, or sheltering (Level
B harassment).
Authorized takes would primarily be by Level B harassment, as use
of seismic airguns has the potential to result in disruption of
behavioral patterns for individual marine mammals. There is also some
potential for auditory injury (Level A harassment) for mysticetes and
high frequency cetaceans (i.e., kogiidae spp.), due to larger predicted
auditory injury zones for those functional hearing groups. The proposed
mitigation and monitoring measures are expected to minimize the
severity of such taking to the extent practicable.
Auditory injury is unlikely to occur for mid-frequency cetaceans,
otariid pinnipeds, and phocid pinnipeds given very small modeled zones
of injury for those species (up to 43.7 m). Moreover, the source level
of the array is a theoretical definition assuming a point source and
measurement in the far-field of the source (MacGillivray, 2006). As
described by Caldwell and Dragoset (2000), an array is not a point
source, but one that spans a small area. In the far-field, individual
elements in arrays will effectively work as one source because
individual pressure peaks will have coalesced into one relatively broad
pulse. The array can then be considered a ``point source.'' For
distances within the near-field, i.e., approximately 2-3 times the
array dimensions, pressure peaks from individual elements do not arrive
simultaneously because the observation point is not equidistant from
each element. The effect is destructive interference of the outputs of
each element, so that peak pressures in the near-field will be
significantly lower than the output of the largest individual element.
Here, the 230 dB peak isopleth distances would in all cases be expected
to be within the near-field of the array where the definition of source
level breaks down. Therefore, actual locations within this distance of
the array center where the sound level exceeds 230 dB peak SPL would
not necessarily exist. In general, Caldwell and Dragoset (2000) suggest
that the near-field for airgun arrays is considered to extend out to
approximately 250 m.
In order to provide quantitative support for this theoretical
argument, we calculated expected maximum distances at which the near-
field would transition to the far-field (Table 5). For a specific array
one can estimate the distance at which the near-field transitions to
the far-field by:
[GRAPHIC] [TIFF OMITTED] TN10JN19.001
with the condition that D > l, and where D is the distance, L is the
longest dimension of the array, and l is the wavelength of the signal
(Lurton 2002). Given that l can be defined by:
[GRAPHIC] [TIFF OMITTED] TN10JN19.002
where f is the frequency of the sound signal and v is the speed of the
sound in the medium of interest, one can rewrite the equation for D as:
[GRAPHIC] [TIFF OMITTED] TN10JN19.003
and calculate D directly given a particular frequency and known speed
of sound (here assumed to be 1,500 meters per second in water, although
this varies with environmental conditions).
To determine the closest distance to the arrays at which the source
level predictions in Table 1 are valid (i.e., maximum extent of the
near-field), we calculated D based on an assumed frequency of 1 kHz. A
frequency of 1 kHz is commonly used in near-field/far-field
calculations for airgun arrays (Zykov and Carr 2014; MacGillivray 2006;
NSF and USGS 2011), and based on representative airgun spectrum data
and field measurements of an airgun array used on the R/V Marcus G.
Langseth, nearly all (greater than 95 percent) of the energy from
airgun arrays is below 1 kHz (Tolstoy et al., 2009). Thus, using 1 kHz
as the upper cut-off for calculating the maximum extent of the near-
field should reasonably represent the near-field extent in field
conditions.
If the largest distance to the peak sound pressure level threshold
was equal to or less than the longest dimension of the array (i.e.,
under the array), or within the near-field, then received levels that
meet or exceed the threshold in most cases are not expected to occur.
This is because within the near-field and within the dimensions of the
array, the source levels specified in Table 1 are overestimated and not
applicable. In fact, until one reaches a distance of approximately
three or four times the near-field distance the average intensity of
sound at any given distance from the array is still less than that
based on calculations that assume a directional point source (Lurton
2002). The 6,600 in\3\ airgun array used in the 2D survey has an
approximate diagonal of 28.8 m, resulting in a near-field distance of
138.7 m at 1 kHz (NSF and USGS 2011). Field measurements of this array
indicate that the source behaves like multiple discrete sources, rather
than a directional point source, beginning at approximately 400 m (deep
site) to 1 km (shallow site) from the center of the array (Tolstoy et
al., 2009), distances that are actually greater than four times the
calculated 140-m near-field distance. Within these distances, the
recorded received levels were always lower than would be predicted
based on calculations that assume a directional point source, and
increasingly so as one moves closer towards the array (Tolstoy et al.,
2009). Similarly, the 3,300 in\3\ airgun array used in the 3D survey
has an approximate diagonal of 17.9 m, resulting in a near-field
distance of 53.5 m at 1 kHz (NSF and USGS 2011). Given this, relying on
the calculated distances (138.7 m for the 2D survey and 53.5 m for the
3D survey) as the distances at which we expect to be in the near-field
is a conservative approach since even beyond this distance the acoustic
modeling still overestimates the actual received level. Within the
near-field, in order to explicitly evaluate the likelihood of exceeding
any particular acoustic threshold, one would need to consider the exact
position of the animal, its relationship to individual array elements,
and how the individual acoustic sources propagate and their acoustic
fields interact. Given that within the near-field and dimensions of the
array source levels would be below those in Table 5, we believe
exceedance of the peak pressure threshold would only be possible under
highly unlikely circumstances.
Therefore, we expect the potential for Level A harassment of mid-
frequency cetaceans, otariid pinnipeds, and phocid pinnipeds to be de
minimis, even before the likely moderating effects of aversion and/or
other compensatory behaviors (e.g., Nachtigall et al., 2018) are
considered. We do not believe that Level A harassment is a likely
outcome for any mid-frequency cetacean, otariid pinniped, or phocid
pinniped and do not propose to authorize any Level A harassment for
these species.
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
[[Page 26960]]
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.
Table 3--Thresholds Identifying the Onset of Permanent Threshold Shift
----------------------------------------------------------------------------------------------------------------
PTS onset acoustic thresholds \*\ (received level)
Health group ------------------------------------------------------------------------
Impulsive Non-impulsive
----------------------------------------------------------------------------------------------------------------
Low-Frequency (LF) Cetaceans........... Cell 1: Lpk,flat: 219 dB; Cell 2: LE,LF,24h: 199 dB.
LE,LF,24h: 183 dB.
Mid-Frequency (MF) Cetaceans........... Cell 3: Lpk,flat: 230 dB; Cell 4: LE,MF,24h: 198 dB.
LE,MF,24h: 185 dB.
High-Frequency (HF) Cetaceans.......... Cell 5: Lpk,flat: 202 dB; Cell 6: LE,HF,24h: 173 dB.
LE,HF,24h: 155 dB.
Phocid Pinnipeds (PW) (Underwater)..... Cell 7: Lpk,flat: 218 dB; Cell 8: LE,PW,24h: 201 dB.
LE,PW,24h: 185 dB.
Otariid Pinnipeds (OW) (Underwater).... Cell 9: Lpk,flat: 232 dB; Cell 10: LE,OW,24h: 219 dB.
LE,OW,24h: 203 dB.
----------------------------------------------------------------------------------------------------------------
* Dual metric acoustic thresholds for impulsive sounds: Use whichever results in the largest isopleth for
calculating PTS onset. If a non-impulsive sound has the potential of exceeding the peak sound pressure level
thresholds associated with impulsive sounds, these thresholds should also be considered.
Note: Peak sound pressure (Lpk) has a reference value of 1 [micro]Pa, and cumulative sound exposure level (LE)
has a reference value of 1[micro]Pa\2\s. In this Table, thresholds are abbreviated to reflect American
National Standards Institute standards (ANSI 2013). However, 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 3D survey would acquire data with the 18-airgun array
with a total discharge of 3,300 in\3\ towed at a depth of 10 m. The
proposed 2D survey would acquire data using 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 18-
airgun array, 36-airgun array, and 40-in\3\ airgun 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 (approximately
1,600 m), intermediate water depth on the slope (approximately 600-
1,100 m), and shallow water (approximately 50 m) in the Gulf of Mexico
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
[[Page 26961]]
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 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 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 model curve. However, the observed sound levels are found to
fall almost entirely below the model curve. Thus, analysis of the Gulf
of Mexico calibration measurements demonstrates that although simple,
the L-DEO model is a robust tool for conservatively estimating
isopleths.
For deep water (>1,000 m), L-DEO used the deep-water radii obtained
from model results down to a maximum water depth of 2000 m. The radii
for intermediate water depths (100-1,000 m) were 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 (See Fig. 16 in Appendix H of NSF-USGS, 2011).
Measurements have not been reported for the single 40-in\3\ airgun.
L-DEO model results are used to determine the 160-dB (rms) radius for
the 40-in\3\ airgun at a 12 m tow depth in deep water (See LGL 2018,
Figure A-2). For intermediate-water depths, a correction factor of 1.5
was applied to the deep-water model results.
L-DEO's modeling methodology is described in greater detail in the
IHA application (LGL 2018). The estimated distances to the Level B
harassment isopleth for the Langseth's 18-airgun array, 36-airgun
array, and single 40-in\3\ airgun are shown in Table 4.
Table 4--Predicted Radial Distances From R/V Langseth Seismic Sources to
Isopleths Corresponding to Level B Harassment Threshold
------------------------------------------------------------------------
Distance (m)
Source and volume Tow depth (m) \a\
------------------------------------------------------------------------
Single Bolt airgun (40 in\3\)........... 12 431
2 strings, 18 airguns (3,300 in\3\)..... 10 3,758
4 strings, 36 airguns (6,600 in\3\)..... 12 6,733
------------------------------------------------------------------------
\a\ Distance based on L-DEO model results.
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 2016). 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 far-field
signature (Table 5). 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 cum thresholds.
Inputs to the User Spreadsheets in the form of estimated SLs are
shown in Table 5. User Spreadsheets used by L-DEO to estimate distances
to Level A harassment isopleths for the 18-airgun array, 36-airgun
array, and single 40 in\3\ airgun for the surveys are shown in Tables
A-3, A-6, and A-10 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 6. 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 6--Modeled Radial Distances (m) to Isopleths Corresponding to Level A Harassment Thresholds
----------------------------------------------------------------------------------------------------------------
Phocid Otariid
Source and volume LF cetaceans MF cetaceans HF cetaceans pinnipeds pinnipeds
----------------------------------------------------------------------------------------------------------------
Single Bolt airgun (40 in\3\):
\a\
PTS SELcum.................. 0.5 0 0 0 0
PTS Peak.................... 1.76 0.51 12.5 1.98 0.4
2 strings, 18 airguns (3300
in\3\):
PTS SELcum.................. 75.6 0 0.3 2.9 0
PTS Peak.................... 23.2 11.2 118.7 25.1 9.9
4 strings, 36 airguns (6600
in\3\):
PTS SELcum.................. 426.9 0 1.3 13.9 0
PTS Peak.................... 38.9 13.6 268.3 43.7 10.6
----------------------------------------------------------------------------------------------------------------
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 developing their IHA application, L-DEO utilized estimates of
cetacean densities in the survey area synthesized by Barlow (2016).
Observations from NMFS Southwest Fisheries Science Center (SWFSC) ship
surveys off of Oregon and Washington (up to 556 km from shore) between
1991 and 2014 were pooled. Systematic, offshore, at-sea survey data for
pinnipeds are more limited. To calculate pinniped densities in the
survey area, L-DEO utilized methods described in U.S. Navy (2010) which
calculated density estimates for pinnipeds off Washington at different
times of the year using information on breeding and migration,
population estimates from shore counts, and areas used by different
species while at sea. The densities calculated by the Navy were updated
by L-DEO using stock abundances presented in the latest SARs (e.g.,
Caretta et al., 2018).
While the IHA application was in review by NMFS, the U.S. Navy
published the Marine Species Density Database Phase III for the
Northwest Training and Testing (NWTT) Study
[[Page 26963]]
Area (Navy 2018). The proposed geophysical survey area is located near
the western boundary of the defined NWTT Offshore Study Area.
For several cetacean species, the Navy updated densities estimated
by line-transect surveys or mark-recapture studies (e.g., Barlow 2016).
These methods usually produce a single value for density that is an
averaged estimate across very large geographical areas, such as waters
within the U.S. EEZ off California, Oregon, and Washington (referred to
as a ``uniform'' density estimate). This is the general approach
applied in estimating cetacean abundance in the NMFS stock assessment
reports. The disadvantage of these methods is that they do not provide
information on varied concentrations of species in sub-regions of very
large areas, and do not estimate density for other seasons or
timeframes that were not surveyed. More recently, a newer method called
spatial habitat modeling has been used to estimate cetacean densities
that address some of these shortcomings (e.g., Barlow et al., 2009;
Becker et al., 2010, 2012a, 2014; Becker et al., 2016; Ferguson et al.,
2006; Forney et al., 2012, 2015; Redfern et al., 2006). (Note that
spatial habitat models are also referred to as ``species distribution
models'' or ``habitat-based density models.'') These models estimate
density as a continuous function of habitat variables (e.g., sea
surface temperature, seafloor depth) and thus, within the study area
that was modeled, densities can be predicted at all locations where
these habitat variables can be measured or estimated. Spatial habitat
models therefore allow estimates of cetacean densities on finer scales
than traditional line-transect or mark-recapture analyses.
The methods used to estimate pinniped at-sea densities are
typically different than those used for cetaceans, because pinnipeds
are not limited to the water and spend a significant amount of time on
land (e.g., at rookeries). Pinniped abundance is generally estimated
via shore counts of animals on land at known haulout sites or by
counting number of pups weaned at rookeries and applying a correction
factor to estimate the abundance of the population (for example Harvey
et al., 1990; Jeffries et al., 2003; Lowry 2002; Sepulveda et al.,
2009). Estimating in-water densities from land-based counts is
difficult given the variability in foraging ranges, migration, and
haulout behavior between species and within each species, and is driven
by factors such as age class, sex class, breeding cycles, and seasonal
variation. Data such as age class, sex class, and seasonal variation
are often used in conjunction with abundance estimates from known
haulout sites to assign an in-water abundance estimate for a given
area. The total abundance divided by the area of the region provides a
representative in-water density estimate for each species in a
different location, which enables analyses of in-water stressors
resulting from at-sea Navy testing or training activities. In addition
to using shore counts to estimate pinniped density, traditional line-
transect derived estimates are also used, particularly in open ocean
areas.
Because the Navy's density calculations for many species included
spatial habitat modeling and demographic information, we utilized the
Navy Marine Species Density Database (NMSDD) to estimate densities and
resulting take of marine mammals from the proposed geophysical survey.
Where available, the appropriate seasonal density estimate from the
NMSDD was used in the estimation here (i.e., summer). For species with
a quantitative density range within or around the proposed survey area,
the maximum presented density was conservatively used. Background
information on the density calculations for each species/guild as well
as reported sightings in nearby waters are reported here. Density
estimates for each species/guild are found in Table 7.
Humpback Whale
NMFS SWFSC developed a CCE habitat-based density model for humpback
whales which provides spatially explicit density estimates off the U.S.
West Coast for summer and fall based on survey data collected between
1991 and 2014 (Becker et al., in prep). Density data are not available
for the NWTT Offshore area northwest of the SWFSC strata, so the
habitat-based density values in the northernmost pixels adjoining this
region were interpolated based on the nearest-neighbor approach to
provide representative density estimates for this area.
Six humpback whale sightings (8 animals) were made off Washington/
Oregon during the June-July 2012 L-DEO Juan de Fuca plate seismic
survey; all were well inshore of the proposed survey area (RPS 2012b).
There were 98 humpback whale sightings (213 animals) made during the
July 2012 L-DEO seismic survey off southern Washington, northeast of
the proposed survey area (RPS 2012a), and 11 sightings (23 animals)
during the July 2012 L-DEO seismic survey off Oregon, southeast of the
proposed survey area (RPS 2012c). No sightings were made near the
proposed survey area in the 2014 NMFS Southwest Fisheries Science
Center (SWFSC) California Current Ecosystem (CCE) vessel survey (Barlow
2016).
Minke Whale
Density values for minke whales are available for the SWFSC Oregon/
Washington and Northern California offshore strata for summer/fall
(Barlow 2016). Density data are not available for the NWTT Offshore
area northwest of the SWFSC strata, so data from the SWFSC Oregon/
Washington stratum were used as representative estimates.
Sightings have been made off Oregon and Washington in shelf and
deeper waters (Green et al., 1992; Adams et al., 2014; Carretta et al.,
2017). An estimated abundance of 211 minke whales was reported for the
Oregon/Washington region based on sightings data from 1991-2005 (Barlow
and Forney 2007), whereas a 2008 survey did not record any minke whales
while on survey effort (Barlow 2010). The abundance for Oregon/
Washington for 2014 was estimated at 507 minke whales (Barlow 2016).
There were no sightings of minke whales off Washington/Oregon during
the June-July 2012 L-DEO Juan de Fuca plate seismic survey or during
the July 2012 L-DEO seismic survey off Oregon, southeast of the
proposed survey area (RPS 2012b, c). One minke whale was seen during
the July 2012 L-DEO seismic survey off southern Washington, north of
the proposed survey area (RPS 2012a). No sightings of minke whales were
made near the proposed survey area during the 2014 SWFSC CCE vessel
survey (Barlow 2016).
Sei Whale
Density values for sei whales are available for the SWFSC Oregon/
Washington and Northern California offshore strata for summer/fall
(Barlow 2016). Density data are not available for the NWTT Offshore
area northwest of the SWFSC strata, so data from the SWFSC Oregon/
Washington stratum were used as representative estimates.
Sei whales are rare in the waters off California, Oregon, and
Washington (Brueggeman et al., 1990; Green et al., 1992; Barlow 1994,
1997). Only 16 confirmed sightings were reported for California,
Oregon, and Washington during extensive surveys from 1991-2014 (Green
et al., 1992, 1993; Hill and Barlow 1992; Carretta and Forney 1993;
Mangels and Gerrodette 1994; Von Saunder and Barlow 1999; Barlow 2003;
Forney 2007; Barlow 2010; Carretta et al., 2017). Based on surveys
conducted in 1991-2008, the estimated abundance
[[Page 26964]]
of sei whales off the coasts of Oregon and Washington was 52 (Barlow
2010); for 2014, the abundance estimate was 468 (Barlow 2016). Two
sightings of four individuals were made during the June-July 2012 L-DEO
Juan de Fuca plate seismic survey off Washington/Oregon (RPS 2012b);
these were well inshore of the proposed survey area (~125[deg] W). No
sei whales were sighted during the July 2012 L-DEO seismic surveys
north and south of the proposed survey area (RPS 2012a, c).
Fin Whale
NMFS SWFSC developed a CCE habitat-based density model for fin
whales which provides spatially explicit density estimates off the U.S.
West Coast for summer and fall based on survey data collected between
1991 and 2014 (Becker et al., in prep). Density data are not available
for the NWTT Offshore area northwest of the SWFSC strata, so the
habitat-based density values in the northernmost pixels adjoining this
region were interpolated based on the nearest-neighbor approach to
provide representative density estimates for this area.
Fin whales are routinely sighted during surveys off Oregon and
Washington (Barlow and Forney 2007; Barlow 2010; Adams et al., 2014;
Calambokidis et al., 2015; Edwards et al., 2015; Carretta et al.,
2017), including in coastal as well as offshore waters. They have also
been detected acoustically near the proposed study area during June-
August (Edwards et al., 2015). There is one sighting of a fin whale in
the Ocean Biogeographic Information System (OBIS) database within the
proposed survey area, which was made in August 2005 during the SWFSC
Collaborative Survey of Cetacean Abundance and the Pelagic Ecosystem
(CSCAPE) Marine Mammal Survey, and several other sightings in adjacent
waters (OBIS 2018). Eight fin whale sightings (19 animals) were made
off Washington/Oregon during the June-July 2012 L-DEO Juan de Fuca
plate seismic survey, including two sightings (4 animals) in the
vicinity of the proposed survey area; sightings were made in waters
2,369-3,940 m deep (RPS 2012b). Fourteen fin whale sightings (28
animals) were made during the July 2012 L-DEO seismic surveys off
southern Washington, northeast of the proposed survey area (RPS 2012a).
No fin whales were sighted during the July 2012 L-DEO seismic survey
off Oregon, southeast of the proposed survey area (RPS 2012c). Fin
whales were also seen off southern Oregon during July 2012 in water
>2,000 m deep during surveys by Adams et al. (2014).
Blue Whale
NMFS SWFSC developed a CCE habitat-based density model for blue
whales which provides spatially explicit density estimates off the U.S.
West Coast for summer and fall based on survey data collected between
1991 and 2014 (Becker et al., in prep). Density data are not available
for the NWTT Offshore area northwest of the SWFSC strata, so the
habitat-based density values in the northernmost pixels adjoining this
region were interpolated based on the nearest-neighbor approach to
provide representative density estimates for this area.
The nearest sighting of blue whales is ~55 km to the southwest
(OBIS 2018), and there are several other sightings in adjacent waters
(Carretta et al., 2018; OBIS 2018). Satellite telemetry suggests that
blue whales are present in waters offshore of Oregon and Washington
during fall and winter (Bailey et al., 2009; Hazen et al., 2017).
Sperm Whale
NMFS SWFSC developed a CCE habitat-based density model for sperm
whales which provides spatially explicit density estimates off the U.S.
West Coast for summer and fall based on survey data collected between
1991 and 2014 (Becker et al., in prep). Density data are not available
for the NWTT Offshore area northwest of the SWFSC strata, so the
habitat-based density values in the northernmost pixels adjoining this
region were interpolated based on the nearest-neighbor approach to
provide representative density estimates for this area.
There is one sighting of a sperm whale in the vicinity of the
survey area in the OBIS database that was made in July 1996 during the
SWFSC ORCAWALE Marine Mammal Survey (OBIS 2018), and several other
sightings in adjacent waters (Carretta et al., 2018; OBIS 2018). Sperm
whale sightings were also made in the vicinity of the proposed survey
area during the 2014 SWFSC vessel survey (Barlow 2016). A single sperm
whale was sighted during the 2009 ETOMO survey, north of the proposed
survey area (Holst 2017). Sperm whales were detected acoustically in
waters near the proposed survey area in August 2016 during the SWFSC
Passive Acoustics Survey of Cetacean Abundance Levels (PASCAL) study
using drifting acoustic recorders (Keating et al., 2018).
Pygmy and Dwarf Sperm Whales (Kogia Guild)
Kogia species are treated as a guild off the U.S. West Coast
(Barlow & Forney 2007). Barlow (2016) provided stratified density
estimates for Kogia spp. for waters off California, Oregon, and
Washington; these were used for all seasons for both the Northern
California and Oregon/Washington strata. In the absence of other data,
the Barlow (2016) Oregon/Washington estimate was also used for the area
northwest of the SWFSC strata for all seasons.
Pygmy and dwarf sperm whales are rarely sighted off Oregon and
Washington, with only one sighting of an unidentified Kogia sp. beyond
the U.S. EEZ, during the 1991-2014 NOAA vessel surveys (Carretta et
al., 2017). This sighting was made in October 1993 during the SWFSC
PODS Marine Mammal Survey ~150 km to the south of the proposed survey
area (OBIS 2018). Norman et al. (2004) reported eight confirmed
stranding records of pygmy sperm whales for Oregon and Washington, five
of which occurred during autumn and winter.
Baird's Beaked Whale
NMFS SWFSC developed a CCE habitat-based density model for Baird's
beaked whale which provides spatially explicit density estimates off
the U.S. West Coast for summer and fall based on survey data collected
between 1991 and 2014 (Becker et al., in prep). Density data are not
available for the NWTT Offshore area northwest of the SWFSC strata, so
the habitat-based density values in the northernmost pixels adjoining
this region were interpolated based on the nearest-neighbor approach to
provide representative density estimates for this area.
Green et al. (1992) sighted five groups during 75,050 km of aerial
survey effort in 1989-1990 off Washington/Oregon spanning coastal to
offshore waters: Two in slope waters and three in offshore waters. Two
groups were sighted during summer/fall 2008 surveys off Washington/
Oregon, in waters >2,000 m deep (Barlow 2010). Acoustic monitoring
offshore Washington detected Baird's beaked whale pulses during January
through November 2011, with peaks in February and July
([Scirc]irovi[cacute] et al., 2012b in USN 2015). Baird's beaked whales
were detected acoustically near the proposed survey area in August 2016
during the SWFSC PASCAL study using drifting acoustic recorders
(Keating et al., 2018). There is one sighting of a Baird's beaked whale
near the survey area in the OBIS database that was made in August 2005
during the SWFSC CSCAPE Marine Mammal Survey (OBIS 2018).
[[Page 26965]]
Small Beaked Whale Guild
NMFS has developed habitat-based density models for a small beaked
whale guild in the CCE (Becker et al., 2012b; Forney et al., 2012). The
small beaked whale guild includes Cuvier's beaked whale and beaked
whales of the genus Mesoplodon, including Blainville's beaked whale,
Hubbs' beaked whale, and Stejneger's beaked whale. NMFS SWFSC developed
a CCE habitat-based density model for the small beaked whale guild
which provides spatially explicit density estimates off the U.S. West
Coast for summer and fall based on survey data collected between 1991
and 2014 (Becker et al., in prep). Density data are not available for
the NWTT Offshore area northwest of the SWFSC strata, so the habitat-
based density values in the northernmost pixels adjoining this region
were interpolated based on the nearest-neighbor approach to provide
representative density estimates for this area.
Four beaked whale sightings were reported in water depths >2,000 m
off Oregon/Washington during surveys in 2008 (Barlow 2010). None were
seen in 1996 or 2001 (Barlow 2003), and several were recorded from 1991
to 1995 (Barlow 1997). One Cuvier's beaked whale sighting was made east
of the proposed survey area during 2014 (Barlow 2016). Acoustic
monitoring in Washington offshore waters detected Cuvier's beaked whale
pulses between January and November 2011 ([Scirc]irovi[cacute] et al.,
2012b in USN 2015). There is one sighting of a Cuvier's beaked whale
near the proposed survey area in the OBIS database that was made in
July 1996 during the SWFSC ORCAWALE Marine Mammal Survey (OBIS 2018),
and several other sightings were made in adjacent waters, primarily to
the south and east of the proposed survey area (Carretta et al., 2018;
OBIS 2018). Cuvier's beaked whales were detected acoustically in waters
near the proposed survey area in August 2016 during the SWFSC PASCAL
study using drifting acoustic recorders (Keating et al., 2018).
There are no sightings of Blainville's beaked whales near the
proposed survey area in the OBIS database (OBIS 2018). There is one
sighting of an unidentified species of Mesoplodont whale near the
survey area in the OBIS database that was made in July 1996 during the
SWFSC ORCAWALE Marine Mammal Survey (OBIS 2018). There was one acoustic
encounter with Blainville's beaked whales recorded in Quinault Canyon
off Washington in waters 1,400 m deep during 2011 (Baumann-Pickering et
al., 2014). Blainville's beaked whales were not detected acoustically
in waters near the proposed survey area in August 2016 during the SWFSC
PASCAL study using drifting acoustic recorders (Keating et al., 2018).
Although Blainville's beaked whales could be encountered during the
proposed survey, an encounter would be unlikely because the proposed
survey area is beyond the northern limits of this tropical species'
usual distribution.
Stejneger's beaked whale calls were detected during acoustic
monitoring offshore Washington between January and June 2011, with an
absence of calls from mid-July to November 2011 ([Scirc]irovi[cacute]
et al., 2012b in USN 2015). Analysis of these data suggest that this
species could be more than twice as prevalent in this area than Baird's
beaked whale (Baumann-Pickering et al., 2014). Stejneger's beaked
whales were also detected acoustically in waters near the proposed
survey area in August 2016 during the SWFSC PASCAL study using drifting
acoustic recorders (Keating et al., 2018). There are no sightings of
Stejneger's beaked whales near the proposed survey area in the OBIS
database (OBIS 2018). There is one sighting of an unidentified species
of Mesoplodont beaked whale near the survey area in the OBIS database
that was made during July 1996 during the SWFSC ORCAWALE Marine Mammal
Survey (OBIS 2018).
Baird's beaked whale is sometimes seen close to shore where deep
water approaches the coast, but its primary habitat is over or near the
continental slope and oceanic seamounts (Jefferson et al., 2015). Along
the U.S. West Coast, Baird's beaked whales have been sighted primarily
along the continental slope (Green et al., 1992; Becker et al., 2012;
Carretta et al., 2018) from late spring to early fall (Green et al.,
1992). The whales move out from those areas in winter (Reyes 1991). In
the eastern North Pacific Ocean, Baird's beaked whales apparently spend
the winter and spring far offshore, and in June, they move onto the
continental slope, where peak numbers occur during September and
October. Green et al. (1992) noted that Baird's beaked whales on the
U.S. West Coast were most abundant in the summer, and were not sighted
in the fall or winter. MacLeod et al. (2006) reported numerous
sightings and strandings of Berardius spp. off the U.S. West Coast.
Bottlenose Dolphin
During surveys off the U.S. West Coast, offshore bottlenose
dolphins were generally found at distances greater than 1.86 miles (3
km) from the coast and were most abundant off southern California
(Barlow 2010, 2016). Based on sighting data collected by SWFSC during
systematic surveys in the Northeast Pacific between 1986 and 2005,
there were few sightings of offshore bottlenose dolphins north of about
40[deg] N (Hamilton et al., 2009). NMFS SWFSC developed a CCE habitat-
based density model for bottlenose dolphins which provides spatially
explicit density estimates off the U.S. West Coast for summer and fall
based on survey data collected between 1991 and 2014 (Becker et al., in
prep). Density data are not available for the NWTT Offshore area
northwest of the SWFSC strata, so the habitat-based density values in
the northernmost pixels adjoining this region were interpolated based
on the nearest-neighbor approach to provide representative density
estimates for this area.
Bottlenose dolphins occur frequently off the coast of California,
and sightings have been made as far north as 41[deg] N, but few records
exist for Oregon/Washington (Carretta et al., 2017). Three sightings
and one stranding of bottlenose dolphins have been documented in Puget
Sound since 2004 (Cascadia Research 2011 in USN 2015). It is possible
that offshore bottlenose dolphins may range as far north as the
proposed survey area during warm-water periods (Carretta et al., 2017).
Adams et al. (2014) made one sighting off Washington during September
2012. There are no sightings of bottlenose dolphins near the proposed
survey area in the OBIS database (OBIS 2018).
Striped Dolphin
Striped dolphin encounters increase in deep, relatively warmer
waters off the U.S. West Coast, and their abundance decreases north of
about 42[deg] N (Barlow et al., 2009; Becker et al., 2012b; Becker et
al., 2016; Forney et al., 2012). Although striped dolphins typically do
not occur north of California, there are a few sighting records off
Oregon and Washington (Barlow 2003, 2010; Von Saunder & Barlow 1999),
and multiple sightings in 2014 when water temperatures were anomalously
warm (Barlow 2016). NMFS SWFSC developed a CCE habitat-based density
model for striped dolphins which provides spatially explicit density
estimates off the U.S. West Coast for summer and fall based on survey
data collected between 1991 and 2014 (Becker et al., in prep). Density
data are not available for the NWTT Offshore area northwest of the
SWFSC strata, so the habitat-based density values in the northernmost
pixels adjoining this region were interpolated based on the
[[Page 26966]]
nearest-neighbor approach to provide representative density estimates
for this area.
Striped dolphins regularly occur off California (Becker et al.,
2012), where they have been seen as far as the ~300 n.mi. limit during
the NOAA Fisheries vessel surveys (Carretta et al., 2017). Strandings
have occurred along the coasts of Oregon and Washington (Carretta et
al., 2016). During surveys off the U.S. West Coast in 2014, striped
dolphins were seen as far north as 44[deg] N (Barlow 2016).
Short-Beaked Common Dolphin
Short-beaked common dolphins are found off the U.S. West Coast
throughout the year, distributed between the coast and at least 345
miles (556 km) from shore (Barlow 2010; Becker et al., 2017; Carretta
et al., 2017b). The short-beaked common dolphin is the most abundant
cetacean species off California (Barlow 2016; Carretta et al., 2017b;
Forney et al., 1995); however, their abudance decreases dramatically
north of about 40[deg] N (Barlow et al., 2009; Becker et al., 2012c;
Becker et al., 2016; Forney et al., 2012). Short-beaked common dolphins
are occasionally sighted in waters off Oregon and Washington, and one
group of approximately 40 short-beaked common dolphins was sighted off
northern Washington in 2005 at about 48[deg] N (Forney 2007), and
multiple groups were sighted as far north as 44[deg] N during
anomalously warm conditions in 2014 (Barlow 2016). NMFS SWFSC developed
a CCE habitat-based density model for short-beaked common dolphins
which provides spatially explicit density estimates off the U.S. West
Coast for summer and fall based on survey data collected between 1991
and 2014 (Becker et al., in prep). Density data are not available for
the NWTT Offshore area northwest of the SWFSC strata, so the habitat-
based density values in the northernmost pixels adjoining this region
were interpolated based on the nearest-neighbor approach to provide
representative density estimates for this area.
There are no sightings of short-beaked dolphins near the proposed
survey area in the OBIS database (OBIS 2018).
Pacific White-Sided Dolphin
Pacific white-sided dolphins occur year-round in the offshore
region of the NWTT Study Area, with increased abundance in the summer/
fall (Barlow 2010; Forney & Barlow 1998; Oleson et al., 2009). NMFS
SWFSC developed a CCE habitat-based density model for Pacific white-
sided dolphins which provides spatially explicit density estimates off
the U.S. West Coast for summer and fall based on survey data collected
between 1991 and 2014 (Becker et al., in prep). Density data are not
available for the NWTT Offshore area northwest of the SWFSC strata, so
the habitat-based density values in the northernmost pixels adjoining
this region were interpolated based on the nearest-neighbor approach to
provide representative density estimates for this area.
Fifteen Pacific white-sided dolphin sightings (231 animals) were
made off Washington/Oregon during the June-July 2012 L-DEO Juan de Fuca
plate seismic survey; none were near the proposed survey area (RPS
2012b). There were fifteen Pacific white-sided dolphin sightings (462
animals) made during the July 2012 L-DEO seismic surveys off southern
Washington, northeast of the proposed survey area (RPS 2012a). This
species was not sighted during the July 2012 L-DEO seismic survey off
Oregon, southeast of the proposed survey area (RPS 2012c). One group of
10 Pacific white-sided dolphins was sighted during the 2009 ETOMO
survey north of the proposed survey area (Holst 2017).
Northern Right Whale Dolphin
Survey data suggest that, at least in the eastern North Pacific,
seasonal inshore-offshore and north-south movements are related to prey
availability, with peak abundance in the Southern California Bight
during winter and distribution shifting northward into Oregon and
Washington as water temperatures increase during late spring and summer
(Barlow 1995; Becker et al., 2014; Forney et al., 1995; Forney & Barlow
1998; Leatherwood & Walker 1979). NMFS SWFSC developed a CCE habitat-
based density model for northern right whale dolphins which provides
spatially explicit density estimates off the U.S. West Coast for summer
and fall based on survey data collected between 1991 and 2014 (Becker
et al., in prep). Density data are not available for the NWTT Offshore
area northwest of the SWFSC strata, so the habitat-based density values
in the northernmost pixels adjoining this region were interpolated
based on the nearest-neighbor approach to provide representative
density estimates for this area.
Seven northern right whale dolphin sightings (231 animals) were
made off Washington/Oregon during the June-July 2012 L-DEO Juan de Fuca
plate seismic survey; none were seen near the proposed survey area (RPS
2012b). There were eight northern right whale dolphin sightings (278
animals) made during the July 2012 L-DEO seismic surveys off southern
Washington, northeast of the proposed survey area (RPS 2012a). This
species was not sighted during the July 2012 L-DEO seismic survey off
Oregon, southeast of the proposed survey area (RPS 2012c).
Risso's Dolphin
NMFS SWFSC developed a CCE habitat-based density model for Risso's
dolphins which provides spatially explicit density estimates off the
U.S. West Coast for summer and fall based on survey data collected
between 1991 and 2014 (Becker et al., in prep). Density data are not
available for the NWTT Offshore area northwest of the SWFSC strata, so
the habitat-based density values in the northernmost pixels adjoining
this region were interpolated based on the nearest-neighbor approach to
provide representative density estimates for this area.
Two sightings of 38 individuals were recorded off Washington from
August 2004 to September 2008 (Oleson et al., 2009). Risso's dolphins
were sighted off Oregon, in June and October 2011 (Adams et al., 2014).
There were three Risso's dolphin sightings (31 animals) made during the
July 2012 L-DEO seismic surveys off southern Washington, northeast of
the proposed survey area (RPS 2012a). This species was not sighted
during the July 2012 L-DEO seismic survey off Oregon, southeast of the
proposed survey area (RPS 2012c), or off Washington/Oregon during the
June-July 2012 L-DEO Juan de Fuca plate seismic survey (RPS 2012b).
False Killer Whale
False killer whales were not included in the NMSDD, as they are
very rarely encountered in the northeast Pacific. Density estimates for
false killer whales were also not presented in Barlow (2016), as no
sightings occurred during surveys conducted between 1986 and 2008
(Ferguson and Barlow 2001, 2003; Forney 2007; Barlow 2003, 2010). One
sighting was made off of southern California during 2014 (Barlow 2016).
There are no sightings of false killer whales near the survey area in
the OBIS database (OBIS 2018).
Killer Whale
Due to the difficulties associated with reliably distinguishing the
different stocks of killer whales from at-sea sightings, density
estimates for the Offshore region of the NWTT Study Area are presented
for the species as a whole (i.e., includes the Offshore, West
[[Page 26967]]
Coast Transient, Northern Resident, and Southern Resident stocks).
Density values for killer whales are available for the SWFSC Oregon/
Washington and Northern California offshore strata for summer/fall
(Barlow 2016). Density data are not available for the NWTT Offshore
area northwest of the SWFSC strata, so data from the SWFSC Oregon/
Washington stratum were used as representative estimates. These values
were used to represent density year-round.
Eleven sightings of ~536 individuals were reported off Oregon/
Washington during the 2008 SWFSC vessel survey (Barlow 2010). Killer
whales were sighted offshore Washington during surveys from August 2004
to September 2008 (Oleson et al., 2009). Keating et al. (2015) analyzed
cetacean whistles from recordings made during 2000-2012; several killer
whale acoustic detections were made offshore Washington.
Short-Finned Pilot Whale
Along the U.S. West Coast, short-finned pilot whales were once
common south of Point Conception, California (Carretta et al., 2017b;
Reilly & Shane 1986), but now sightings off the U.S. West Coast are
infrequent and typically occur during warm water years (Carretta et
al., 2017b). Stranding records for this species from Oregon and
Washington waters are considered to be beyond the normal range of this
species rather than an extension of its range (Norman et al., 2004).
Density values for short-finned pilot whales are available for the
SWFSC Oregon/Washington and Northern California strata for summer/fall
(Barlow 2016). Density data are not available for the NWTT Offshore
area northwest of the SWFSC strata, so data from the SWFSC Oregon/
Washington stratum were used as representative estimates. These values
were used to represent density year-round.
Few sightings were made off California/Oregon/Washington in 1984-
1992 (Green et al., 1992; Carretta and Forney 1993; Barlow 1997), and
sightings remain rare (Barlow 1997; Buchanan et al., 2001; Barlow
2010). No short-finned pilot whales were seen during surveys off Oregon
and Washington in 1989-1990, 1992, 1996, and 2001 (Barlow 2003). A few
sightings were made off California during surveys in 1991-2014 (Barlow
2010). Carretta et al. (2017) reported one sighting off Oregon during
1991-2008. Several stranding events in Oregon/southern Washington have
been recorded over the past few decades, including in March 1996, June
1998, and August 2002 (Norman et al., 2004).
Dall's Porpoise
NMFS SWFSC developed a CCE habitat-based density model for Dall's
porpoise which provides spatially explicit density estimates off the
U.S. West Coast for summer and fall based on survey data collected
between 1991 and 2014 (Becker et al., in prep). Density data are not
available for the NWTT Offshore area northwest of the SWFSC strata, so
the habitat-based density values in the northernmost pixels adjoining
this region were interpolated based on the nearest-neighbor approach to
provide representative density estimates for this area.
Oleson et al. (2009) reported 44 sightings of 206 individuals off
Washington during surveys form August 2004 to September 2008. Dall's
porpoise were seen in the waters off Oregon during summer, fall, and
winter surveys in 2011 and 2012 (Adams et al., 2014). Nineteen Dall's
porpoise sightings (144 animals) were made off Washington/Oregon during
the June-July 2012 L-DEO Juan de Fuca plate seismic survey; none were
in near the proposed survey area (RPS 2012b). There were 16 Dall's
porpoise sightings (54 animals) made during the July 2012 L-DEO seismic
surveys off southern Washington, northeast of the proposed survey area
(RPS 2012a). This species was not sighted during the July 2012 L-DEO
seismic survey off Oregon, southeast of the proposed survey area (RPS
2012c). Dall's porpoise was the most frequently sighted marine mammal
species (5 sightings of 28 animals) during the 2009 ETOMO survey north
of the proposed survey area (Holst 2017).
Northern Fur Seal
The Navy estimated the abundance of northern fur seals from the
Eastern Pacific stock and the California breeding stock that could
occur in the NWTT Offshore Study Area by determining the percentage of
time tagged animals spent within the Study Area and applying that
percentage to the population to calculate an abundance for adult
females, juveniles, and pups independently on a monthly basis. Adult
males are not expected to occur within the Offshore Study Area and the
proposed survey area during the proposed geophysical survey as they
spend the summer ashore at breeding areas in the Bering Sea and San
Miguel Island (Caretta et al., 2017b). Using the monthly abundances of
fur seals within the Offshore Study Area, the Navy created strata to
estimate the density of fur seals within three strata: 22 km to 70 km
from shore, 70 km to 130 km from shore, and 130 km to 463 km from shore
(the western Study Area boundary). L-DEO's proposed survey is 423 km
from shore at the closest point. Based on satellite tag data and
historic sealing records (Olesiuk 2012; Kajimura 1984), the Navy
assumed 25 percent of the population present within the overall
Offshore Study Area may be within the 130 km to 463 km stratum.
Thirty-one northern fur seal sightings (63 animals) were made off
Washington/Oregon during the June-July 2012 L-DEO Juan de Fuca plate
seismic survey north of the proposed survey area (RPS 2012b). There
were six sightings (6 animals) made during the July 2012 L-DEO seismic
surveys off southern Washington, northeast of the proposed survey area
(RPS 2012a). This species was not sighted during the July 2012 L-DEO
seismic survey off Oregon, southeast of the proposed survey area (RPS
2012c).
Guadalupe Fur Seal
As with northern fur seals, adult male Guadalupe fur seals are
expected to be ashore at breeding areas over the summer, and are not
expected to be present during the proposed geophysical survey (Caretta
et al., 2017b; Norris 2017b). Additionally, breeding females are
unlikely to be present within the Offshore Study Area as they remain
ashore to nurse their pups through the fall and winter, making only
short foraging trips from rookeries (Gallo-Reynoso et al., 2008; Norris
2017b; Yochem et al., 1987). To estimate the total abundance of
Guadalupe fur seals, the Navy adjusted the population reported in the
2016 SAR (Caretta et al., 2017b) of 20,000 seals by applying the
average annual growth rate of 7.64 percent over the seven years between
2010 and 2017. The resulting 2017 projected abundance was 33,485 fur
seals. Using the reported composition of the breeding population of
Guadalupe fur seals (Gallo-Reynoso 1994) and satellite telemetry data
(Norris 2017b), the Navy established seasonal and demographic
abundances of fur seals expected to occur within the Offshore Study
Area.
The distribution of Guadalupe fur seals in the Offshore Study Area
was stratified by distance from shore (or water depth) to reflect their
preferred pelagic habitat (Norris 2017a). Ten percent of fur seals in
the Study Area are expected to use waters over the continental shelf
(approximated as waters with depths between 10 and 200 m). A depth of
10 m is used as the shoreward extent of the shelf (rather than
extending to shore), because Guadalupe fur seals in the Offshore
[[Page 26968]]
Study Area are not expected to haul out and would not be likely to come
close to shore. All fur seals (i.e., 100 percent) would use waters off
the shelf (beyond the 200 m isobath) out to 300 km from shore, and 25
of percent of fur seals would be expected to use waters between 300 and
700 km from shore (including the proposed geophysical survey area). The
second stratum (200 m to 300 km from shore) is the preferred habitat
where Guadalupe fur seals are most likely to occur most of the time.
Individuals may spend a portion of their time over the continental
shelf or farther than 300 km from shore, necessitating a density
estimate for those areas, but all Guadalupe fur seals would be expected
to be in the central stratum most of the time, which is the reason 100
percent is used in the density estimate for the central stratum (Norris
2017a). Spatial areas for the three strata were estimated in a GIS and
used to calculate the densities.
Guadalupe fur seals have not previously been observed in the
proposed survey area, nor on previous L-DEO surveys off Washington and
Oregon.
Northern Elephant Seal
The most recent surveys supporting the abundance estimate for
northern elephant seals were conducted in 2010 (Caretta et al., 2017b).
By applying the average growth rate of 3.8 percent per year for the
California breeding stock over the seven years from 2010 to 2017, the
Navy calculated a projected 2017 abundance estimate of 232,399 elephant
seals (Caretta et al., 2017b; Lowry et al., 2014). Male and female
distributions at sea differ both seasonally and spatially. Pup counts
reported by Lowry et al. (2014) and life tables compiled by Condit et
al. (2014) were used to determine the proportion of males and females
in the population, which was estimated to be 56 percent female and 44
percent male. Females are assumed to be at sea 100 percent of the time
within their seasonal distribution area in fall and summer (Robinson et
al., 2012). Males are at sea approximately 90 percent of the time in
fall and spring, remain ashore through the entire winter, and spend one
month ashore to molt in the summer (i.e., are at sea 66 percent of the
summer). Monthly distribution maps produced by Robinson et al. (2012)
showing the extent of foraging areas used by satellite tagged female
elephant seals were used to estimate the spatial areas to calculate
densities. Although the distributions were based on tagged female
seals, Le Boeuf et al. (2000) and Simmons et al. (2007) reported
similar tracks by males over broad spatial scales. The spatial areas
representing each monthly distribution were calculating using GIS and
then averaged to produce seasonally variable areas and resulting
densities.
Off Washington, most elephant seal sightings at sea were made
during June, July, and September; off Oregon, sightings were recorded
from November through May (Bonnell et al. 1992). Several seals were
seen off Oregon during summer, fall, and winter surveys in 2011 and
2012 (Adams et al. 2014). Northern elephant seals were also taken as
bycatch off Oregon in the west coast groundfish fishery during 2002-
2009 (Jannot et al. 2011). Northern elephant seals were sighted five
times (5 animals) during the July 2012 L-DEO seismic surveys off
southern Washington, northeast of the proposed survey area (RPS 2012a).
This species was not sighted during the July 2012 L-DEO seismic survey
off Oregon, southeast of the proposed survey area (RPS 2012c), or off
Washington/Oregon during the June-July 2012 L-DEO Juan de Fuca plate
seismic survey that included the proposed survey area (RPS 2012b). One
northern elephant seal was sighted during the 2009 ETOMO survey north
of the proposed survey area (Holst 2017).
Table 7--Marine Mammal Density Values in the Proposed Survey Area
------------------------------------------------------------------------
Reported
Species density (#/
km\2\) \a\
------------------------------------------------------------------------
LF Cetaceans:
Humpback whale............................................ 0.001829
Minke whale............................................... 0.0013
Sei whale................................................. 0.0004
Fin whale................................................. 0.004249
Blue whale................................................ 0.001096
MF Cetaceans:
Sperm whale............................................... 0.002561
Cuvier's and Mesoplodont beaked whales.................... 0.007304
Baird's beaked whale...................................... 0.00082
Bottlenose dolphin........................................ 0.000003
Striped dolphin........................................... 0.009329
Short-beaked common dolphin............................... 0.124891
Pacific white-sided dolphin............................... 0.017426
Northern right-whale dolphin.............................. 0.039962
Risso's dolphin........................................... 0.007008
False killer whale........................................ N/A
Killer whale.............................................. \b\
0.00092
Short-finned pilot whale.................................. 0.00025
HF Cetaceans:
Kogia spp................................................. 0.00163
Dall's porpoise........................................... 0.043951
Otariids:
Northern fur seal......................................... \b\ 0.0103
Guadalupe fur seal........................................ 0.0029
Phocids:
Northern elephant seal.................................... 0.0309
------------------------------------------------------------------------
\a\ Navy 2018.
\b\ No stock-specific densities are available so densities are presumed
equal for all stocks present.
Take Calculation and Estimation
Here we describe how the information provided above is brought
together to produce a quantitative take estimate. In order to estimate
the number of marine mammals predicted to be exposed to sound levels
that would result in Level A or Level B harassment, radial distances
from the airgun array to predicted isopleths corresponding to the Level
A harassment and Level B harassment thresholds are calculated, as
described above. Those radial distances are then used to calculate the
area(s) around the airgun array predicted to be ensonified to sound
levels that exceed the Level A and Level B harassment thresholds. The
area estimated to be ensonified in a single day of the survey is then
calculated (Table 8), based on the areas predicted to be ensonified
around the array and representative trackline distances traveled per
day. This number is then multiplied by the number of survey days. 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 and Level B harassment
thresholds.
Table 8--Areas (km\2\) Estimated To Be Ensonified to Level A and Level B Harassment Thresholds, per Day
--------------------------------------------------------------------------------------------------------------------------------------------------------
Daily Total
Survey Criteria Relevant ensonified Total survey 25% increase ensonified
isopleth (m) area (km\2\) days area (km\2\)
--------------------------------------------------------------------------------------------------------------------------------------------------------
2-D Survey................................ Level B Harassment
-------------------------------------------------------------------------------------------------------------
[[Page 26969]]
160-dB...................... 6,733 1,346.90 3 1.25 5,050.86
-------------------------------------------------------------------------------------------------------------
Level A Harassment
-------------------------------------------------------------------------------------------------------------
LF Cetaceans................ 426.9 158.67 3 1.25 595.01
HF Cetaceans................ 268.3 99.77 3 1.25 374.12
Phocids..................... 43.7 16.26 3 1.25 60.96
MF Cetaceans................ 13.6 5.06 3 1.25 18.97
Otariids.................... 10.6 3.94 3 1.25 14.79
--------------------------------------------------------------------------------------------------------------------------------------------------------
3-D Survey Level B Harassment
-------------------------------------------------------------------------------------------------------------
160-dB...................... 3,758 690.52 16 1.25 13,810.40
-------------------------------------------------------------------------------------------------------------
Level A Harassment
-------------------------------------------------------------------------------------------------------------
LF Cetaceans................ 118.7 47.39 16 1.25 947.74
HF Cetaceans................ 75.6 30.13 16 1.25 602.59
Phocids..................... 25.1 9.98 16 1.25 199.59
MF Cetaceans................ 11.2 4.45 16 1.25 89.01
Otariids.................... 9.9 3.93 16 1.25 78.67
--------------------------------------------------------------------------------------------------------------------------------------------------------
The marine mammals predicted to occur within these respective
areas, based on estimated densities, are assumed to be incidentally
taken. For species where take by Level A harassment has been requested,
the calculated Level A takes have been subtracted from the total
exposures within the Level B harassment zone. Estimated exposures for
the proposed survey are shown in Table 9.
Table 9--Estimated Level A and Level B Exposures, and Percentage of Stock Exposed
----------------------------------------------------------------------------------------------------------------
Percent of
Species Stock Level B Level A Total take stock
----------------------------------------------------------------------------------------------------------------
LF Cetaceans
----------------------------------------------------------------------------------------------------------------
Humpback whale................ California/ 32 3 35 1.21
Oregon/
Washington.
Minke whale................... California/ 23 2 25 3.93
Oregon/
Washington.
Sei whale..................... Eastern North 7 1 8 1.54
Pacific.
Fin whale..................... California/ 74 7 81 0.90
Oregon/
Washington.
Blue whale.................... Eastern North 19 2 21 1.28
Pacific.
----------------------------------------------------------------------------------------------------------------
MF Cetaceans
----------------------------------------------------------------------------------------------------------------
Sperm whale................... California/ 48 0 48 2.40
Oregon/
Washington.
Cuvier's and Mesoplodont California/ 138 0 138 \a\ 2.18
beaked whales. Oregon/
Washington.
Baird's beaked whale.......... California/ 15 0 15 0.56
Oregon/
Washington.
Bottlenose dolphin............ California/ \b\ 13 0 \b\ 13 0.68
Oregon/
Washington.
Striped dolphin............... California/ 176 0 176 0.60
Oregon/
Washington.
Short-beaked common dolphin... California/ 2,356 0 2,356 0.24
Oregon/
Washington.
Pacific white-sided dolphin... California/ 329 0 329 1.23
Oregon/
Washington.
Northern right-whale dolphin.. California/ 754 0 749 2.82
Oregon/
Washington.
Risso's dolphin............... California/ 132 0 132 2.08
Oregon/
Washington.
False killer whale............ Hawaii Pelagic.. \b\ 5 0 \b\ 5 0.32
Killer whale.................. Offshore........ 17 0 17 \c\ 5.67
West Coast .............. .............. .............. \c\ 7.00
Transient.
Short-finned pilot whale...... California/ \b\ 18 0 \b\ 18 2.15
Oregon/
Washington.
----------------------------------------------------------------------------------------------------------------
HF Cetaceans
----------------------------------------------------------------------------------------------------------------
Kogia spp..................... California/ 31 2 29 0.71
Oregon/
Washington.
Dall's porpoise............... California/ 829 43 786 3.05
Oregon/
Washington.
----------------------------------------------------------------------------------------------------------------
Otariids
----------------------------------------------------------------------------------------------------------------
Northern fur seal............. Eastern Pacific. 194 0 194 \c\ 0.03
California...... .............. .............. .............. \c\ 1.38
[[Page 26970]]
Guadalupe fur seal............ Mexico.......... 55 0 55 0.28
----------------------------------------------------------------------------------------------------------------
Phocids
----------------------------------------------------------------------------------------------------------------
Northern elephant seal........ California 583 0 583 0.33
Breeding.
----------------------------------------------------------------------------------------------------------------
\a\ Combined stock abundances for Cuvier's beaked whales and Mesoplodont guild.
\b\ Calculated take increased to mean group size (Barlow 2016).
\c\ Where multiple stocks are affected, for the purposes of calculating the percentage of stock affected, takes
are analyzed as if all takes occurred within each stock.
It should be noted that the proposed take numbers shown in Table 9
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 due to the different density estimates used, and in
consideration of the near-field soundscape of the airgun array, 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).
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 (latter not applicable for this action). NMFS
regulations require applicants for incidental take authorizations to
include information about the availability and feasibility (economic
and technological) of equipment, methods, and manner of conducting 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.
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; and (7) Vessel strike
avoidance 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 meter
exclusion zone, out to a radius of 1,000 meters from the edges of the
airgun array (500-1,000 meters). 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
exclusion zone by alerting the visual observer and crew of marine
mammals
[[Page 26971]]
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 acoustic source (i.e.,
anytime airguns are 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.
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) should 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 Exclusion and Buffer Zones
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
[[Page 26972]]
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 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.
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; and
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 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
[[Page 26973]]
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, pygmy sperm, dwarf sperm, and
beaked 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--
Tursiops, Delphinus, Lagenodelphis, Lagenorhynchus, Lissodelphis,
Stenella and Steno--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 delphinoid exception because power-down/
shutdown requirements for small delphinoids under all circumstances
represent practicability concerns without likely commensurate benefits
for the animals in question. Small delphinoids 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 delphinoids
commonly approach vessels and/or towed arrays during active sound
production for purposes of bow riding, with no apparent effect observed
in those delphinoids (e.g., Barkaszi et al., 2012). The potential for
increased shutdowns resulting from such a measure would require the
Langseth to revisit the missed track line to reacquire data, resulting
in an overall increase in the total sound energy input to the marine
environment and an increase in the total duration over which the survey
is active in a given area. Although other mid-frequency hearing
specialists (e.g., large delphinoids) are no more likely to incur
auditory injury than are small delphinoids, they are much less likely
to approach vessels. Therefore, retaining a power-down/shutdown
requirement for large delphinoids 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 delphinoids 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; and
5. When marine mammals are sighted while a vessel is underway, the
vessel 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
[[Page 26974]]
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.
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 five 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:
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:
[[Page 26975]]
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); and
Any additional information recorded such as water depth of
the hydrophone array, bearing of the animal to the vessel (if
determinable), species or taxonomic group (if determinable),
spectrogram screenshot, and any other notable information.
Reporting
A report would be submitted to NMFS within 90 days after the end of
the cruise. The report would 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 and including an estimate of those
that were not detected, in consideration of both the characteristics
and behaviors of the species of marine mammals that affect
detectability, as well as the environmental factors that affect
detectability.
L-DEO will be required to 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 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.
Reporting Injured or Dead Marine Mammals
In the event that personnel involved in survey activities covered
by the authorization discover an injured or dead marine mammal, the L-
DEO shall report the incident to the Office of Protected Resources
(OPR), NMFS and to the NMFS West Coast Regional Stranding Coordinator
as soon as feasible. The report must include the following information:
Time, date, and location (latitude/longitude) of the first
discovery (and updated location information if known and applicable);
Species identification (if known) or description of the
animal(s) involved;
Condition of the animal(s) (including carcass condition if
the animal is dead);
[[Page 26976]]
Observed behaviors of the animal(s), if alive;
If available, photographs or video footage of the
animal(s); and
General circumstances under which the animal was
discovered.
Additional Information Requests--If NMFS determines that the
circumstances of any marine mammal stranding found in the vicinity of
the activity suggest investigation of the association with survey
activities is warranted (example circumstances noted below), and an
investigation into the stranding is being pursued, NMFS will submit a
written request to the IHA-holder indicating that the following initial
available information must be provided as soon as possible, but no
later than 7 business days after the request for information.
Status of all sound source use in the 48 hours preceding
the estimated time of stranding and within 50 km of the discovery/
notification of the stranding by NMFS; and
If available, description of the behavior of any marine
mammal(s) observed preceding (i.e., within 48 hours and 50 km) and
immediately after the discovery of the stranding.
Examples of circumstances that could trigger the additional
information request include, but are not limited to, the following:
Atypical nearshore milling events of live cetaceans;
Mass strandings of cetaceans (two or more individuals, not
including cow/calf pairs);
Beaked whale strandings;
Necropsies with findings of pathologies that are unusual
for the species or area; or
Stranded animals with findings consistent with blast
trauma.
In the event that the investigation is still inconclusive, the
investigation of the association of the survey activities is still
warranted, and the investigation is still being pursued, NMFS may
provide additional information requests, in writing, regarding the
nature and location of survey operations prior to the time period
above.
Vessel Strike--In the event of a ship strike of a marine mammal by
any vessel involved in the activities covered by the authorization, L-
DEO must shall report the incident to OPR, NMFS and to regional
stranding coordinators as soon as feasible. The report must include the
following information:
Time, date, and location (latitude/longitude) of the
incident;
Species identification (if known) or description of the
animal(s) involved;
Vessel's speed during and leading up to the incident;
Vessel's course/heading and what operations were being
conducted (if applicable);
Status of all sound sources in use;
Description of avoidance measures/requirements that were
in place at the time of the strike and what additional measures were
taken, if any, to avoid strike;
Environmental conditions (e.g., wind speed and direction,
Beaufort sea state, cloud cover, visibility) immediately preceding the
strike;
Estimated size and length of animal that was struck;
Description of the behavior of the marine mammal
immediately preceding and following the strike;
If available, description of the presence and behavior of
any other marine mammals immediately preceding the strike;
Estimated fate of the animal (e.g., dead, injured but
alive, injured and moving, blood or tissue observed in the water,
status unknown, disappeared); and
To the extent practicable, photographs or video footage of
the animal(s).
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
Tables 7 and 9, given that NMFS expects the anticipated effects of the
proposed geophysical survey to be similar in nature. Where there are
meaningful differences between species or stocks, or groups of species,
in anticipated individual responses to activities, impact of expected
take on the population due to differences in population status, or
impacts on habitat, NMFS has identified species-specific factors to
inform the analysis.
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
harassment of seven species and Level B harassment of 26 marine mammal
species. 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 that are considered to be of low severity
and with no lasting biological consequences (e.g., Southall et al.,
2007). The proposed geophysical survey occurs outside of the U.S. EEZ
and outside of
[[Page 26977]]
any established Biologically Important Areas or critical habitat.
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
(~19 days) and temporary nature of the disturbance, the availability of
similar habitat and resources in the surrounding area, the impacts to
marine mammals and the food sources that they utilize are not expected
to cause significant or long-term consequences for individual marine
mammals or their populations.
The activity is expected to impact a small percentage of all marine
mammal stocks that would be affected by L-DEO's proposed survey (less
than seven percent of all species). 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 some extent of potential PTS in marine
mammals that may otherwise occur in the absence of the proposed
mitigation.
The ESA-listed marine mammal species under our jurisdiction that
are likely to be taken by the proposed surveys include the endangered
sei, fin, blue, sperm, and Central America DPS humpback whales, and the
threatened Mexico DPS humpback whale and Guadalupe fur seal. We propose
to authorize very small numbers of takes for these species relative to
their population sizes. Given the low probability of fitness impacts to
any individual, combined with the small portion of any of these stocks
impacted, we do not expect population-level impacts to any of these
species. The other marine mammal species that may be taken by
harassment during the proposed survey are not listed as threatened or
endangered under the ESA. With the exception of the northern fur seal,
none of the non-listed marine mammals for which we propose to authorize
take are considered ``depleted'' or ``strategic'' by NMFS under the
MMPA.
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 (19 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 PTS that may occur are expected
to be very small in number. Instances of 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; and
The proposed mitigation measures, including visual and
acoustic monitoring, power-downs, and shutdowns, are expected to
minimize potential impacts to marine mammals.
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 Sections 101(a)(5)(A) and (D) of the MMPA for
specified activities other than military readiness activities. The MMPA
does not define small numbers and so, in practice, where estimated
numbers are available, NMFS compares the number of individuals taken to
the most appropriate estimation of abundance of the relevant species or
stock in our determination of whether an authorization is limited to
small numbers of marine mammals. Additionally, other qualitative
factors may be considered in the analysis, such as the temporal or
spatial scale of the activities.
Table 9 provides the numbers of take by Level A and Level B
harassment proposed for authorization, which are used herefor purposes
of the small numbers analysis. The numbers of marine mammals that we
propose for authorized take would be considered small relative to the
relevant populations (less than seven percent for all species and
stocks) for the species for which abundance estimates are available.
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
There are no relevant subsistence uses of the affected marine
mammal stocks or species implicated by this action. Therefore, NMFS has
preliminarily determined that the total taking of affected species or
stocks would not have an unmitigable adverse impact on the availability
of such species or stocks for taking for subsistence purposes.
[[Page 26978]]
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 sei whales, fin whales, blue
whales, sperm whales, Central America DPS humpback whales, Mexico DPS
humpback whales and Guadalupe fur seals which are listed under the ESA.
The Permit 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 a marine geophysical survey in the
northeast Pacific Ocean in 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); and
(2) A preliminary monitoring report showing the results of the
required monitoring to date and an explanation showing that the
monitoring results do not indicate impacts of a scale or nature not
previously analyzed or authorized.
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: June 3, 2019.
Donna S. Wieting,
Director, Office of Protected Resources, National Marine Fisheries
Service.
[FR Doc. 2019-12010 Filed 6-7-19; 8:45 am]
BILLING CODE 3510-22-P
