[Federal Register Volume 84, Number 140 (Monday, July 22, 2019)]
[Notices]
[Pages 35073-35099]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2019-15516]
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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; issuance of an incidental harassment authorization.
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SUMMARY: In accordance with the regulations implementing the Marine
Mammal Protection Act (MMPA) as amended, notification is hereby given
that NMFS has issued an incidental harassment authorization (IHA) to
Lamont-Doherty Earth Observatory (L-DEO) to incidentally harass, by
Level A and Level B harassment, marine mammals during seismic
activities associated with a marine geophysical survey in the Northeast
Pacific Ocean.
DATES: This Authorization is effective from July 10, 2019 through July
9, 2020.
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:
[[Page 35074]]
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.
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 Specified Activity
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), plan 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 planned two-dimensional (2-D) and
three-dimensional (3-D) seismic surveys would occur in International
Waters outside of the U.S. Exclusive Economic 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 total survey
duration would be approximately 35 days. A total of ~3,760 kilometers
(km) of transect lines would be surveyed in the Northeast Pacific
Ocean: ~3,196 km during the 3-D survey and 564 km during the 2-D
survey.
A detailed description of the planned geophysical survey is
provided in the Federal Register notice for the proposed IHA (84 FR
26940; June 10, 2019). Since that time, no changes have been made to
the planned survey activities. Therefore, a detailed description is not
provided here. Please refer to that Federal Register notice for the
description of the specific activity.
Comments and Responses
A notice of NMFS's proposal to issue an IHA to L-DEO was published
in the Federal Register on June 10, 2019 (84 FR 26940). That notice
described, in detail, L-DEO's activity, the marine mammal species that
may be affected by the activity, and the anticipated effects on marine
mammals. During the 30-day public comment period, NMFS received
comments from the Marine Mammal Commission (Commission).
Comment: The Commission recommended that NMFS require L-DEO to re-
estimate the proposed Level A and Level B harassment zones and
associated takes of marine mammals using (1) both operational
(including number/type/spacing of airguns, tow depth, source level/
operating pressure, operational volume) and site-specific environmental
(including sound speed profiles, bathymetry, and sediment
characteristics at a minimum) parameters, (2) a comprehensive source
model (i.e., Gundalf Optimizer or AASM) and (3) an appropriate sound
propagation model for the proposed incidental harassment authorization.
Specifically, the Commission reiterates that L-DEO should be using the
ray-tracing propagation model BELLHOP--which is a free, standard
propagation code that readily incorporates all environmental inputs
listed herein, rather than the limited, in-house MATLAB code currently
in use.
Response: NMFS acknowledges the Commission's concerns about L-DEO's
current modeling approach for estimating Level A and Level B harassment
zones and takes. L-DEO's application and the Federal Register notice of
the proposed IHA (84 FR 26940; June 10, 2019) describe the applicant's
approach to modeling Level A and Level B harassment zones. The model L-
DEO currently uses does not allow for the consideration of
environmental and site-specific parameters as requested by the
Commission.
L-DEO's application describes their approach to modeling Level A
and Level B harassment zones. In summary, L-DEO acquired field
measurements for several array configurations at shallow, intermediate,
and deep-water depths during acoustic verification studies conducted in
the northern Gulf of Mexico in 2007 and 2008 (Tolstoy et al., 2009).
Based on the empirical data from those studies, L-DEO developed a sound
propagation modeling approach that predicts received sound levels as a
function of distance from a particular airgun array configuration in
deep water. For this survey, L-DEO modeled Level A and Level B
harassment zones based on the empirically-derived measurements from the
Gulf of Mexico calibration survey (Appendix H of NSF-USGS 2011). L-DEO
used the deep-water radii obtained from model results down to a maximum
water depth of 2,000 meters (m) (Figures 2 and 3 in Appendix H of NSF-
USGS 2011).
In 2015, LDEO explored the question of whether the Gulf of Mexico
calibration data described above adequately informs the model to
predict exclusion isopleths in other areas by conducting a
retrospective sound power analysis of one of the lines acquired during
L-DEO's seismic survey offshore New Jersey in 2014 (Crone, 2015). NMFS
presented a comparison of the predicted radii (i.e., modeled exclusion
zones) with radii based on in situ measurements (i.e., the upper bound
[95th percentile] of the cross-line prediction) in a previous notice of
issued Authorization for LDEO (see 80 FR 27635, May 14, 2015, Table 1).
Briefly, the analysis presented in Crone (2015), specific to the survey
site offshore New Jersey, confirmed that in-situ, site specific
measurements and estimates of 160 decibel (dB) and 180 dB isopleths
collected by the hydrophone streamer of the R/V Langseth in shallow
water were smaller than the modeled (i.e., predicted) zones for two
seismic surveys conducted offshore New Jersey in shallow water in 2014
and 2015. In that particular case, Crone's (2015) results showed that
L-DEO's modeled 180 decibel (dB) and
[[Page 35075]]
160 dB zones were approximately 28 percent and 33 percent larger,
respectively, than the in-situ, site-specific measurements, thus
confirming that L-DEO's model was conservative in that case.
The following is a summary of two additional analyses of in-situ
data that support L-DEO's use of the modeled Level A and Level B
harassment zones in this particular case. In 2010, L-DEO assessed the
accuracy of their modeling approach by comparing the sound levels of
the field measurements acquired in the Gulf of Mexico study to their
model predictions (Diebold et al., 2010). They reported that the
observed sound levels from the field measurements fell almost entirely
below the predicted mitigation radii curve for deep water (i.e.,
greater than 1,000 m; 3,280.8 ft) (Diebold et al., 2010). In 2012, L-
DEO used a similar process to model distances to isopleths
corresponding to Level A and Level B harassment thresholds for a
shallow-water seismic survey in the northeast Pacific Ocean offshore
Washington State. LDEO conducted the shallow-water survey using a 6,600
in\3\ airgun configuration aboard the R/V Langseth and recorded the
received sound levels on both the shelf and slope using the Langseth's
8 km hydrophone streamer. Crone et al. (2014) analyzed those received
sound levels from the 2012 survey and confirmed that in-situ, site
specific measurements and estimates of the 160 dB and 180 dB isopleths
collected by the Langseth's hydrophone streamer in shallow water were
two to three times smaller than L-DEO's modeling approach had
predicted. While the results confirmed the role of bathymetry in sound
propagation, Crone et al. (2014) were also able to confirm that the
empirical measurements from the Gulf of Mexico calibration survey (the
same measurements used to inform L-DEO's modeling approach for the
planned surveys in the northwest Atlantic Ocean) overestimated the size
of the exclusion and buffer zones for the shallow-water 2012 survey off
Washington State and were thus precautionary, in that particular case.
NMFS continues to work with L-DEO to address the issue of
incorporating site-specific information for future authorizations for
seismic surveys. However, L-DEO's current modeling approach (supported
by the three data points discussed previously) represents the best
available information for NMFS to reach determinations for this IHA. As
described earlier, the comparisons of L-DEO's model results and the
field data collected at multiple locations (i.e., the Gulf of Mexico,
offshore Washington State, and offshore New Jersey) illustrate a degree
of conservativeness built into L-DEO's model for deep water, which NMFS
expects to offset some of the limitations of the model to capture the
variability resulting from site-specific factors. Based upon the best
available information (i.e., the three data points, two of which are
peer-reviewed, discussed in this response), NMFS finds that the Level A
and Level B harassment zone calculations are appropriate for use in
this particular IHA.
The use of models for calculating Level A and Level B harassment
zones and for developing take estimates is not a requirement of the
MMPA incidental take authorization process. Further, NMFS does not
prescribe specific model parameters nor a specific model for applicants
as part of the MMPA incidental take authorization process at this time,
although we do review methods to ensure they adequately predict take.
There is a level of variability not only with parameters in the models,
but also the uncertainty associated with data used in models, and
therefore, the quality of the model results submitted by applicants.
NMFS considers this variability when evaluating applications and the
take estimates and mitigation measures that the model informs. NMFS
takes into consideration the model used, and its results, in
determining the potential impacts to marine mammals; however, it is
just one component of the analysis during the MMPA authorization
process as NMFS also takes into consideration other factors associated
with the activity (e.g., geographic location, duration of activities,
context, sound source intensity, etc.).
Comment: Given the shortcomings noted for L-DEO's source and sound
propagation modeling and the requirements that other action proponents
are obliged to fulfill, the Commission recommended that NMFS require L-
DEO to archive, analyze, and compare the in-situ data collected by the
hydrophone streamer and ocean bottom seismometers (OBSs) to L-DEO's
modeling results for the extents of the Level A and B harassment zones
based on the various water depths to be surveyed and provide the data
and results to NMFS.
Response: Based on information presented by the applicant and
supported by published analysis such as Diebold et al. 2010, Tolstoy et
al. 2009, Crone et al. 2014, Crone et al. 2017, Barton et al. 2006, and
Diebold et al. 2006, L-DEO modeling results and predicted distances to
harassment zones are likely more conservative than actual distances
measured from data collected in situ for depths from shallow to deep.
The Commission stated one reason for recommending that NMFS require L-
DEO to conduct sound source verification efforts was due to the short-
comings of the L-DEO model. However, as previously noted, the L-DEO
model is conservative and is viewed appropriate for R/V Langseth
operations. Use of the L-DEO model is further supported by ten years of
successful operations with no observed harm to marine life. For these
reasons, additional sound source verification efforts are not warranted
at this time.
Comment: The Commission recommended that NMFS recalculate the
densities (and thus, estimated take) of Guadalupe fur seals, northern
fur seals, and northern elephant seals to include more recent data and
population growth through 2019 rather than 2017.
Response: Through discussions with the Commission, NMFS has
recalculated the densities of these species. The density of Guadalupe
fur seals increased to 0.00343 animals per square kilometer (km\2\),
the density of northern fur seals increased to 0.01065 animals per
km\2\, and the density of northern elephant seals increased to 0.03333
animals per km\2\. Estimated take of these three species increased
accordingly. Further detail regarding these changes is included in the
Estimated Take section later in this document.
Comment: The Commission recommended that NMFS use a consistent
approach for requiring all geophysical and seismic survey operators to
abide by the same general mitigation measures, including prohibiting L-
DEO from using power downs and the mitigation airgun during its
geophysical surveys.
Response: NMFS is in the process of developing protocols that could
be applied to geophysical and seismic surveys. The protocols are being
developed on the basis of detailed review of available literature,
including peer-reviewed science, review articles, gray literature, and
protocols required by other countries around the world. NMFS will share
the protocols with the Commission when they are ready for external
comment and review.
Note that power downs to the single 40 in\3\ airgun are only
allowed/required in lieu of shutdown when certain species of dolphins,
specifically identified in the Mitigation section below, enter the
shutdown zone. In all other cases, shutdown would be implemented under
conditions as described in the IHA.
Comment: The Commission noted that monitoring and reporting
requirements adopted need to be
[[Page 35076]]
sufficient to provide a reasonably accurate assessment of the manner of
taking and the numbers of animals taken incidental to the specified
activity. Those assessments should account for all animals in the
various survey areas, including those animals directly on the trackline
that are not detected and how well animals are detected based on the
distance from the observer which is achieved by incorporating g(0) and
f(0) values. The Commission recommended that NMFS require L-DEO to use
the Commission's method as described in the Commission's Addendum to
better estimate the numbers of marine mammals taken by Level A and B
harassment for the incidental harassment authorization. The Commission
stated that all other NSF-affiliated entities and all seismic operators
should use this method as well.
Response: NMFS agrees that reporting of the manner of taking and
the numbers of animals incidentally taken should account for all
animals taken, including those animals that are not detected and how
well animals are detected based on the distance from the observer, to
the extent practicable. NMFS appreciates the Commission's
recommendations and further requires that L-DEO provide an estimate of
take, including marine mammals that were not detected in their
reporting for this survey, as it has in previous actions. NMFS welcomes
L-DEO's input on a method to generate this quantitative method, but in
the absence of a new procedure, recommends that use of the Commission's
method for marine geophysical surveys, which was attached to the
Commission's comment letter. We look forward to engaging further with
L-DEO, the Commission and other applicants to refine methods to
incorporate consideration of g(0) and f(0) values into post-survey take
estimates.
Comment: The commission recommended that NMFS refrain from using
the proposed renewal process for L-DEO's authorization based on the
complexity of analysis and potential for impacts on marine mammals, and
the potential burden on reviewers of reviewing key documents and
developing comments quickly. Additionally, the Commission recommends
that NMFS use the IHA renewal process sparingly and selectively for
activities expected to have the lowest levels of impacts to marine
mammals and that require less complex analysis.
Response: We appreciate the Commission's input and direct the
reader to our recent response to the identical comment, which can be
found at 84 FR 31032 (June 28, 2019), pg. 31035-31036
Comment: The Commission noted that the proposed surveys are
scheduled to begin immediately after the public comment period closed
and expressed concern that NMFS did not have adequate time to consider
public comments before issuing the IHA. The Commission recommended NMFS
more thoroughly review applications, draft Federal Register notices,
and draft proposed authorizations prior to submitting any proposed
authorizations to the Federal Register, as well as require earlier
submission of applications and other documentation to ensure sufficient
time to prepare the proposed authorization and consider comments
received from the public.
Response: NMFS thanks the Commission for its concerns regarding the
IHA process. NMFS thoroughly reviewed the comments received and
considered all comments in making appropriate revisions to the final
IHA. NMFS encourages all applicants to submit applications for IHAs
five to eight months in advance of the intended project start date and
for rulemakings/LOAs at least nine months, and preferably 15 months, in
advance of the intended project start date. More generally, NMFS
publishes Federal Register notices for proposed IHAs as quickly as
possible once the application is received and aims to allow more time
on the back end of the comment period, but there are situations where
the length of processing times are driven by the exigency of an
applicant's activity start date or by the need to work with applicants
to ensure we have the necessary information to deem an application
adequate and complete. Here, NMFS provided the required 30-day notice
for public comment, and has adequately considered the comments received
in making the necessary findings for this IHA.
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).
[[Page 35077]]
Table 1--Marine Mammals That Could Occur in the Survey Area
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ESA/MMPA Stock abundance
status; (CV, Nmin, most
Common name Scientific name Stock strategic (Y/ recent abundance PBR Annual M/SI \3\
N) \1\ survey) \2\
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Order Cetartiodactyla--Cetacea--Superfamily Mysticeti (baleen whales)
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Family Eschrichtiidae:...........
Gray whale................... Eschrichtius Eastern North -/-; N 26,960 (0.05, 801................. 138.
robustus. Pacific. 25,849, 2016).
Western North E/D; Y 175 (0.05, 167, 0.07................ 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).
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).
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Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
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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.................. <0.1.
Washington. 2014).
Baird's beaked whale......... Berardius bairdii.. California/Oregon/ -/-; N 2,697 (0.6, 1,633, 16.................. 0.
Washington. 2014).
Blainville's beaked whale.... Mesoplodon California/Oregon/ -/-; N 3,044 (0.54, 1,967, 20.................. 0.1.
densirostris. Washington. 2014).
Hubbs' beaked whale.......... Mesoplodon
carlshubbi.
Stejneger's beaked whale..... Mesoplodon
stejnegeri.
Family Delphinidae:
Bottlenose dolphin........... Tursiops truncatus. California/Oregon/ -/-; N 1,924 (0.54, 1,255, 11.................. >1.6.
Washington 2014).
offshore.
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 Hawaii Pelagic..... -/-; N 1,540 (0.66, 928, 9.3................. 7.6.
crassidens. 2010).
Killer whale................. Orcinus orca....... Offshore........... -/-; N 240 (0.49, 162, 1.6................. 0.
2014).
Southern Resident.. E/D; Y 83 (N/A, 83, 2016). 0.14................ 0.
Northern Resident.. -/-; N 261 (N/A, 261, 1.96................ 0.
2011).
West Coast -/-; N 243 (N/A, 243, 2.4................. 0.
Transient. 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).
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Order Carnivora--Superfamily Pinnipedia
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Family Otariidae (eared seals
and sea lions):
Northern fur seal............ Callorhinus ursinus Eastern Pacific.... -/D; Y 620,660 (0.2, 11,295.............. 457.
525,333, 2016).
California......... -/D; N 14,050 (N/A, 7,524, 451................. 1.8.
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).
[[Page 35078]]
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).
Northern elephant seal....... Mirounga California Breeding -/-; N 179,000 (N/A, 4,882............... 8.8.
angustirostris. 81,368, 2010).
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\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 or authorized to be taken.
All species that could potentially occur in the planned 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.
A detailed description of the species likely to be affected by L-
DEO's planned surveys, including brief introductions to the species and
relevant stocks as well as available information regarding population
trends and threats, and information regarding local occurrence, were
provided in the Federal Register notice for the proposed IHA (84 FR
26940; June 10, 2019). Since that time, we are not aware of any changes
in the status of these species and stocks; therefore, detailed
descriptions are not provided here. Please refer to that Federal
Register notice for these descriptions. Please also refer to the NMFS
website (https://www.fisheries.noaa.gov/find-species) for generalized
species accounts.
Marine Mammal Hearing
Hearing is the most important sensory modality for marine mammals
underwater, and exposure to anthropogenic sound can have deleterious
effects. To appropriately assess the potential effects of exposure to
sound, it is necessary to understand the frequency ranges marine
mammals are able to hear. 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)
------------------------------------------------------------------------
Generalized hearing range *
Hearing group (kHz)
------------------------------------------------------------------------
Low-frequency (LF) cetaceans (baleen 7 Hz to 35.
whales).
Mid-frequency (MF) cetaceans (dolphins, 150 Hz to 160.
toothed whales, beaked whales, bottlenose
whales).
High-frequency (HF) cetaceans (true 275 Hz to 160.
porpoises, Kogia, river dolphins,
cephalorhynchid, Lagenorhynchus cruciger &
L. australis).
Phocid pinnipeds (PW) (underwater) (true 50 Hz to 86.
seals).
Otariid pinnipeds (OW) (underwater) (sea 60 Hz to 39.
lions and fur seals).
------------------------------------------------------------------------
* Represents the generalized hearing range for the entire group as a
composite (i.e., all species within the group), where individual
species' hearing ranges are typically not as broad. Generalized
hearing range chosen based on ~65 dB threshold from normalized
composite audiogram, with the exception for lower limits for LF
cetaceans (Southall et al. 2007) and PW pinniped (approximation).
The pinniped functional hearing group was modified from Southall et
al. (2007) on the basis of data indicating that phocid species have
consistently demonstrated an extended frequency range of hearing
compared to otariids, especially in the higher frequency range
(Hemil[auml] et al., 2006; Kastelein et al., 2009; Reichmuth and Holt,
2013).
For more detail concerning these groups and associated frequency
ranges, please see NMFS (2018) for a review of available information.
26 marine mammal species (23 cetacean and three
[[Page 35079]]
pinniped (two otariid and one phocid) species) have the reasonable
potential to co-occur with the planned 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
The effects of underwater noise from seismic airguns and other
associated activities for the Northeast Pacific geophysical surveys
have the potential to result in behavioral harassment and a small
degree of permanent threshold shift (PTS) in marine mammals in the
vicinity of the action area associated direct effects on marine
mammals. The project would not result in permanent impacts to habitats
used directly by marine mammals, such as haulout sites, but may have
potential short-term impacts to food sources such as forage fish or
zooplankton during the geophysical survey. These potential effects are
discussed in detail in the Federal Register notice for the proposed IHA
(84 FR 26940; June 10, 2019), therefore that information is not
repeated here. Please refer to that Federal Register notice for that
information.
The main impact associated with L-DEO's Northeast Pacific
geophysical survey would be temporarily elevated sound levels and the
associated direct effects on marine mammals. The project would not
result in permanent impacts to habitats used directly by marine
mammals, such as haulout sites, but may have potential short-term
impacts to food sources such as forage fish or zooplankton during the
geophysical survey. These potential effects are discussed in detail in
the Federal Register notice for the proposed IHA (84 FR 26940; June 10,
2019), therefore that information is not repeated here. Please refer to
that Federal Register notice for that information.
Estimated Take
This section provides an estimate of the number of incidental takes
authorized through this IHA, which will inform both NMFS' consideration
of ``small numbers'' and the negligible impact determination. Based on
input received during the public comment period, minor changes were
made to the densities of three species of marine mammals (northern fur
seal, Guadalupe fur seal, and northern elephant seal) and the number of
Level A takes for sei whales. Takes of these species have been adjusted
accordingly, but these changes do not affect any of our findings.
Harassment is the only type of take expected to result from these
activities. Except with respect to certain activities not pertinent
here, section 3(18) of the MMPA defines ``harassment'' as any act of
pursuit, torment, or annoyance, which (i) has the potential to injure a
marine mammal or marine mammal stock in the wild (Level A harassment);
or (ii) has the potential to disturb a marine mammal or marine mammal
stock in the wild by causing disruption of behavioral patterns,
including, but not limited to, migration, breathing, nursing, breeding,
feeding, or sheltering (Level B harassment).
Authorized takes would primarily be by Level B harassment, as use
of seismic airguns has the potential to result in disruption of
behavioral patterns 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 required
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] TN22JY19.005
with the condition that D >> [lambda], and where D is the distance, L
is the longest dimension of the array, and [lambda] is the wavelength
of the signal (Lurton, 2002). Given that [lambda] can be defined by:
[GRAPHIC] [TIFF OMITTED] TN22JY19.006
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] TN22JY19.007
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
[[Page 35080]]
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 authorized
for this activity. Below we describe how the take is estimated.
Generally speaking, we estimate take by considering: (1) Acoustic
thresholds above which NMFS believes the best available science
indicates marine mammals will be behaviorally harassed or incur some
degree of permanent hearing impairment; (2) the area or volume of water
that will be ensonified above these levels in a day; (3) the density or
occurrence of marine mammals within these ensonified areas; and, (4)
and the number of days of activities. We note that while these basic
factors can contribute to a basic calculation to provide an initial
prediction of takes, additional information that can qualitatively
inform take estimates is also sometimes available (e.g., previous
monitoring results or average group size). Below, we describe the
factors considered here in more detail and present the authorized take.
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 micropascal ([mu]Pa) (root mean square
(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 planned 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 planned 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)
Hearing 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.
[[Page 35081]]
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 [mu]Pa, and cumulative sound exposure level (LE) has
a reference value of 1[mu]Pa\2\s. In this Table, thresholds are abbreviated to reflect American National
Standards Institute standards (ANSI 2013). However, peak sound pressure is defined by ANSI as incorporating
frequency weighting, which is not the intent for this Technical Guidance. Hence, the subscript ``flat'' is
being included to indicate peak sound pressure should be flat weighted or unweighted within the generalized
hearing range. The subscript associated with cumulative sound exposure level thresholds indicates the
designated marine mammal auditory weighting function (LF, MF, and HF cetaceans, and PW and OW pinnipeds) and
that the recommended accumulation period is 24 hours. The cumulative sound exposure level thresholds could be
exceeded in a multitude of ways (i.e., varying exposure levels and durations, duty cycle). When possible, it
is valuable for action proponents to indicate the conditions under which these acoustic thresholds will be
exceeded.
Ensonified Area
Here, we describe operational and environmental parameters of the
activity that will feed into identifying the area ensonified above the
acoustic thresholds, which include source levels and transmission loss
coefficient.
The planned 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
planned 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 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
[[Page 35082]]
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 <1 km), the pulses of sound pressure from each
individual airgun in the source array do not stack constructively, as
they do for the theoretical farfield signature. The pulses from the
different airguns spread out in time such that the source levels
observed or modeled are the result of the summation of pulses from a
few airguns, not the full array (Tolstoy et al. 2009). At larger
distances, away from the source array center, sound pressure of all the
airguns in the array stack coherently, but not within one time sample,
resulting in smaller source levels (a few dB) than the source level
derived from the farfield signature. Because the farfield signature
does not take into account the large array effect near the source and
is calculated as a point source, the modified farfield signature is a
more appropriate measure of the sound source level for distributed
sound sources, such as airgun arrays. L-DEO used the acoustic modeling
methodology as used for Level B harassment with a small grid step of 1
m in both the inline and depth directions. The propagation modeling
takes into account all airgun interactions at short distances from the
source, including interactions between subarrays which are modeled
using the NUCLEUS software to estimate the notional signature and
MATLAB software to calculate the pressure signal at each mesh point of
a grid.
For a more complete explanation of this modeling approach, please
see ``Appendix A: Determination of Mitigation Zones'' in the IHA
application.
Table 5--Modeled Source Levels Based on Modified Farfield Signature for the R/V Langseth 3,300 in\3\ Airgun
Array, 6,600 in\3\ Airgun Array, and Single 40 in\3\ Airgun
----------------------------------------------------------------------------------------------------------------
High Phocid Otariid
Low frequency Mid frequency frequency pinnipeds pinnipeds
cetaceans cetaceans cetaceans (underwater) (underwater)
(Lpk,flat: 219 (Lpk,flat: 230 (Lpk,flat: 202 (Lpk,flat: 218 (Lpk,flat: 232
dB; LE,LF,24h: dB; LE,MF,24h: dB; LE,HF,24h: dB; LE,HF,24h: dB; LE,HF,24h:
183 dB) 185 dB) 155 dB) 185 dB) 203 dB)
----------------------------------------------------------------------------------------------------------------
3,300 in\3\ airgun array (Peak 245.29 250.97 243.61 246.00 251.92
SPLflat).......................
3.300 in\3\ airgun array 226.38 226.33 226.66 226.33 227.07
(SELcum).......................
6,600 in\3\ airgun array (Peak 252.06 252.65 253.24 252.25 252.52
SPLflat).......................
6,600 in\3\ airgun array 232.98 232.84 233.10 232.84 232.08
(SELcum).......................
40 in\3\ airgun (Peak SPLflat).. 223.93 224.09 223.92 223.95 223.95
40 in\3\ airgun (SELcum)........ 202.99 202.89 204.37 202.89 202.35
----------------------------------------------------------------------------------------------------------------
In order to more realistically incorporate the Technical Guidance's
weighting functions over the seismic array's full acoustic band,
unweighted spectrum data for the Langseth's airgun array (modeled in 1
hertz (Hz) bands) was used to make adjustments (dB) to the unweighted
spectrum levels, by frequency, according to the weighting functions for
each relevant marine mammal hearing group. These adjusted/weighted
spectrum levels were then converted to pressures ([mu]Pa) in order to
integrate them over the entire broadband spectrum, resulting in
broadband weighted source levels by hearing group that could be
directly incorporated within the User Spreadsheet (i.e., to override
the Spreadsheet's more simple weighting factor adjustment). Using the
User Spreadsheet's ``safe distance'' methodology for mobile sources
(described by Sivle et al., 2014) with the hearing group-specific
weighted source levels, and inputs assuming spherical spreading
propagation and source
[[Page 35083]]
velocities and shot intervals specific to each of the three planned
surveys provided in the IHA application, potential radial distances to
auditory injury zones were then calculated for SELcum
thresholds.
Inputs to the User Spreadsheets in the form of estimated SLs are
shown in Table 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 11.8 118.7 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 planned 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 Area (Navy 2018). The
planned 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
[[Page 35084]]
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 planned 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 planned 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 planned 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 planned survey area (RPS 2012a), and 11 sightings (23 animals)
during the July 2012 L-DEO seismic survey off Oregon, southeast of the
planned survey area (RPS 2012c). No sightings were made near the
planned 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 planned
survey area (RPS 2012b,c). One minke whale was seen during the July
2012 L-DEO seismic survey off southern Washington, north of the planned
survey area (RPS 2012a). No sightings of minke whales were made near
the planned 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 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 planned survey area (~125[deg] W). No sei whales were
sighted during the July 2012 L-DEO seismic surveys north and south of
the planned 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 planned 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
planned 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 planned 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 planned survey area (RPS 2012a).
No fin whales were sighted during the July 2012 L-DEO seismic survey
off Oregon, southeast of the planned 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
[[Page 35085]]
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 planned survey
area during the 2014 SWFSC vessel survey (Barlow 2016). A single sperm
whale was sighted during the 2009 ETOMO survey, north of the planned
survey area (Holst 2017). Sperm whales were detected acoustically in
waters near the planned 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 planned 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 planned 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).
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 planned 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 planned 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 planned survey area (Carretta et al. 2018; OBIS
2018). Cuvier's beaked whales were detected acoustically in waters near
the planned 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
planned 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 planned 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
planned survey, an encounter would be unlikely because the planned
survey area is beyond the northern limits of this tropical species'
usual distribution.
[[Page 35086]]
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 planned 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 planned 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 planned
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 planned 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 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 abundance 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 planned
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
[[Page 35087]]
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 planned 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 planned survey area (RPS 2012a). This
species was not sighted during the July 2012 L-DEO seismic survey off
Oregon, southeast of the planned survey area (RPS 2012c). One group of
10 Pacific white-sided dolphins was sighted during the 2009 ETOMO
survey north of the planned 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 planned 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 planned survey area (RPS 2012a). This
species was not sighted during the July 2012 L-DEO seismic survey off
Oregon, southeast of the planned 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 planned survey area (RPS 2012a). This species was not sighted
during the July 2012 L-DEO seismic survey off Oregon, southeast of the
planned 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 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
[[Page 35088]]
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 planned 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 planned survey area
(RPS 2012a). This species was not sighted during the July 2012 L-DEO
seismic survey off Oregon, southeast of the planned 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 planned 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
planned survey area during the planned 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 planned 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.
During the public comment period, the Commission noted that the
Navy's density estimates for northern fur seals did not include
abundance data collected from Bogoslof Island in 2015. Incorporating
the 2015 Bogoslof counts yielded an increased abundance estimate, and
thus an increased density of northern fur seals. The density estimate
increased from 0.0103 animals/km\2\ to 0.01065 animals/km\2\. As a
result, the estimated take of northern fur seals increased from 194
takes by Level B harassment to 201. No Level A take of northern fur
seals is anticipated nor authorized.
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 planned 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 planned survey area
(RPS 2012a). This species was not sighted during the July 2012 L-DEO
seismic survey off Oregon, southeast of the planned 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 planned 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 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 planned 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.
During the public comment period, the Commission noted that the
Navy density estimate for Guadalupe fur seals projected the abundance
through 2017, while L-DEO's survey will occur in 2019. The Commission
recommended calculating the abundance estimate in 2019 using the annual
growth rate above. This calculation yielded an increased density
estimate of Guadalupe fur seals, from 0.0029 animals/km\2\ to 0.00343
animals/km\2\. As such, the take estimate increased from 55 takes by
Level B harassment to 65. No Level A take of Guadalupe fur seals is
anticipated or authorized.
Guadalupe fur seals have not previously been observed in the
planned 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
[[Page 35089]]
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.
Similar to the Guadalupe fur seal above, the Commission suggested
using the population growth rate above to calculate the abundance of
northern elephant seals in 2019. The resulting density estimate of
northern elephant seals increased from 0.0309 animals/km\2\ to 0.03333
animals/km\2\. As such, the estimated take by Level B harassment
increased from 583 to 629 animals. Take of northern elephant seals by
Level A harassment is not anticipated or authorized.
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 planned survey area (RPS 2012a).
This species was not sighted during the July 2012 L-DEO seismic survey
off Oregon, southeast of the planned survey area (RPS 2012c), or off
Washington/Oregon during the June-July 2012 L-DEO Juan de Fuca plate
seismic survey that included the planned survey area (RPS 2012b). One
northern elephant seal was sighted during the 2009 ETOMO survey north
of the planned survey area (Holst 2017).
Table 7--Marine Mammal Density Values in the 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 c 0.01065
Guadalupe fur seal.................................. \c\ 0.00343
Phocids:
Northern elephant seal.............................. \c\ 0.03333
------------------------------------------------------------------------
\a\ Navy 2018.
\b\ No stock-specific densities are available so densities are presumed
equal for all stocks present.
\c\ Density estimate increased from that presented in Federal Register
notice of proposed IHA (84 FR 26940; June 10, 2019).
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\)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Level B Harassment
-------------------------------------------------------------------------------------------------------------
2-D Survey................................ 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
--------------------------------------------------------------------------------------------------------------------------------------------------------
Level B Harassment
-------------------------------------------------------------------------------------------------------------
[[Page 35090]]
3-D Survey................................ 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. During the public comment
period, the Commission noted that the typical group size for sei whales
is two animals (Barlow 2016) and recommended increasing the Level A
take to two animals and reducing the Level B takes to six animals. NMFS
agreed and has made that change. Authorized takes for the planned
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 6 2 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 California/ 2356 0 2356 0.24
dolphin. Oregon/
Washington.
Pacific white-sided California/ 329 0 329 1.23
dolphin. Oregon/
Washington.
Northern right-whale California/ 754 0 754 2.82
dolphin. 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/ 29 2 31 0.71
Oregon/
Washington.
Dall's porpoise........... California/ 786 43 829 3.05
Oregon/
Washington.
Otariids:
Northern fur seal......... Eastern Pacific. 201 0 201 \c\ 0.03
California...... .............. .............. .............. \c\ 1.43
Guadalupe fur seal........ Mexico.......... 65 0 65 0.33
Phocids:
Northern elephant seal.... California 629 0 629 0.35
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 authorized 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
[[Page 35091]]
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 have
authorized a different number of incidental takes than the number of
incidental takes requested by L-DEO (see Table 6 in the IHA
application).
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 required 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 is required to implement
mitigation measures for marine mammals. Mitigation measures that would
be adopted during the planned 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 m
exclusion zone, out to a radius of 1,000 m from the edges of the airgun
array (500-1,000 m). Visual monitoring of the exclusion zones and
adjacent waters is intended to establish and, when visual conditions
allow, maintain zones around the sound source that are clear of marine
mammals, thereby reducing or eliminating the potential for injury and
minimizing the potential for more severe behavioral reactions for
animals occurring close to the vessel. Visual monitoring of the buffer
zone is intended to (1) provide additional protection to na[iuml]ve
marine mammals that may be in the area during pre-clearance, and (2)
during airgun use, aid in establishing and maintaining the exclusion
zone by alerting the visual observer and crew of marine mammals that
are outside of, but may approach and enter, the exclusion zone.
L-DEO must use at least five dedicated, trained, NMFS-approved
Protected Species Observers (PSOs). The PSOs must have no tasks other
than to conduct observational effort, record observational data, and
communicate with and instruct relevant vessel crew with regard to the
presence of marine mammals and mitigation requirements. PSO resumes
shall be provided to NMFS for approval.
At least one of the visual and two of the acoustic PSOs aboard the
vessel must have a minimum of 90 days at-sea experience working in
those roles, respectively, during a deep penetration (i.e., ``high
energy'') seismic survey, with no more than 18 months elapsed since the
conclusion of the at-sea experience. One visual PSO with such
experience shall be designated as the lead for the entire protected
species observation team. The lead PSO shall serve as primary point of
contact for the vessel operator and ensure all PSO requirements per the
IHA are met. To the maximum extent practicable, the experienced PSOs
should be scheduled to be on duty with those PSOs with appropriate
training but who have not yet gained relevant experience.
During survey operations (e.g., any day on which use of the
acoustic source is planned to occur, and whenever the acoustic source
is in the water, whether activated or not), a minimum of two visual
PSOs must be on duty and conducting visual observations at all times
during daylight hours (i.e., from 30 minutes prior to sunrise through
30 minutes following sunset) and 30 minutes prior to and during
nighttime ramp-ups of the airgun array. Visual monitoring of the
exclusion and buffer zones must begin no less than 30 minutes prior to
ramp-up and must continue until one hour after use of the acoustic
source ceases or until 30 minutes past sunset. Visual PSOs shall
coordinate to ensure 360[deg] visual coverage around the vessel from
the most appropriate observation posts, and shall conduct visual
observations using binoculars and the naked eye while free from
distractions and in a consistent, systematic, and diligent manner.
PSOs shall establish and monitor the exclusion and buffer zones.
These zones shall be based upon the radial distance from the edges of
the acoustic source
[[Page 35092]]
(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. The 500-m EZ would be based on radial distance from any element
of the airgun array (rather than being based on the center of the array
or around the vessel itself). With certain exceptions (described
below), if a marine mammal appears within or enters this zone, the
acoustic source would be shut down.
The 500-m EZ is intended to be precautionary in the sense that it
would 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.
An extended EZ of 1,500 m must be enforced for all beaked whales,
and dwarf and pygmy sperm whales.
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
[[Page 35093]]
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 pinnipeds, and 30 minutes for all mysticetes and all
other odontocetes, including sperm whales, pygmy sperm whales, dwarf
sperm whales, beaked whales, pilot whales, and Risso's dolphins);
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 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 whales, pygmy
sperm whales, dwarf sperm whales, pilot whales, beaked whales, and
Risso's dolphins.
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 applies solely to specific genera of small dolphins--
Tursiops, Delphinus, Stenella, Lagenorhynchus, and Lissodelphis. The
acoustic source must 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
[[Page 35094]]
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 pinnipeds, and 30 minutes for mysticetes and all other odontocetes,
including sperm whales, pygmy sperm whales, dwarf sperm whales, beaked
whales, pilot whales, and Risso's dolphins, with no further observation
of the marine mammal(s).
The following shutdown requirements have been added to the final
IHA as they were not included in the proposed IHA:
L-DEO must implement shutdown if a marine mammal species
for which take was not authorized, or a species for which authorization
was granted but the takes have been met, approaches the Level A or
Level B harassment zones;
L-DEO must implement shutdown if any large whale (defined
as a sperm whale or any mysticete species) with a calf (defined as an
animal less than two-thirds the body size of an adult observed to be in
close association with an adult) or an aggregation of six or more large
whales is observed at any distance; and
L-DEO must implement shutdown if a North Pacific right
whale is observed at any distance.
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 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 required
measures, NMFS has 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.
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
[[Page 35095]]
of the species and of the level of taking or impacts on populations of
marine mammals that are expected to be present in the 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:
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
[[Page 35096]]
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 is 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);
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
[[Page 35097]]
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
planned geophysical survey to be similar in nature. Where there are
meaningful differences between species or stocks, or groups of species,
in anticipated individual responses to activities, impact of expected
take on the population due to differences in population status, or
impacts on habitat, NMFS has identified species-specific factors to
inform the analysis.
NMFS does not anticipate that serious injury or mortality would
occur as a result of L-DEO's planned survey, even in the absence of
mitigation. Thus the 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 have authorized 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 planned 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).
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 planned survey (less
than seven percent of all species). Additionally, the acoustic
``footprint'' of the planned survey would be small relative to the
ranges of the marine mammals that would potentially be affected. Sound
levels would increase in the marine
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environment in a relatively small area surrounding the vessel compared
to the range of the marine mammals within the planned survey area. The
planned geophysical survey occurs outside of the U.S. EEZ and outside
of any established Biologically Important Areas or critical habitat.
The required 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 required 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 required
mitigation.
The ESA-listed marine mammal species under our jurisdiction that
are likely to be taken by the planned 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 have
authorized 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 planned surveys 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 planned 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 authorized take to impact annual rates of recruitment or
survival.
In summary and as described above, the following factors primarily
support our determination that the impacts resulting from this activity
are not expected to adversely affect the species or stock through
effects on annual rates of recruitment or survival:
No mortality is anticipated or authorized;
The planned activity is temporary and of relatively short
duration (19 days);
The anticipated impacts of the planned 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 planned 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 planned
survey would be temporary and spatially limited; and
The required 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 required monitoring and
mitigation measures, NMFS finds that the total marine mammal take from
the planned activity will have a negligible impact on all affected
marine mammal species or stocks.
Small Numbers
As noted 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 authorized numbers of take by Level A and
Level B harassment, which are used here for purposes of the small
numbers analysis. The numbers of marine mammals that we have authorized
to be taken by Level A and Level B harassment 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 planned activity
(including the required mitigation and monitoring measures) and the
anticipated take of marine mammals, NMFS 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
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.
National Environmental Policy Act
In compliance with the National Environmental Policy Act of 1969
(42 U.S.C. 4321 et seq.), as implemented by the regulations published
by the Council on Environmental Quality (40 CFR parts 1500-1508), the
NSF prepared an Environmental Analysis (EA) to consider the direct,
indirect, and cumulative effects to the human environment from this
marine geophysical survey in the Northeast Pacific. NSF's EA was made
available to the public for review and comment in relation to its
suitability for adoption by NMFS in order to assess the impacts to the
human environment of issuance of an IHA to L-DEO. In compliance with
NEPA and the CEQ regulations, as well as NOAA Administrative Order 216-
6, NMFS has review the NSF's EA, determined it to be sufficient, and
adopted that EA and signed a Finding of No Significant Impact (FONSI)
on July 10, 2019.
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
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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.
The NMFS Office of Protected Resources Interagency Cooperation
Division issued a Biological Opinion on July 10, 2019, under section 7
of the ESA, on the issuance of an IHA to L-DEO under section
101(a)(5)(D) of the MMPA by the NMFS Permits and Conservation Division.
The Biological Opinion concluded that the proposed action is not likely
to jeopardize the continued existence of sei whale, fin whale, blue
whale, sperm whale, humpback whale (Central America DPS and Mexico
DPS), and Guadalupe fur seal, and is not likely to destroy or modify
critical habitat of listed species because no critical habitat exists
for these species in the action area.
Authorization
NMFS has issued an IHA to L-DEO for the potential harassment of
small numbers of 26 marine mammal species incidental to a marine
geophysical survey in the Northeast Pacific, provided the previously
mentioned mitigation, monitoring, and reporting are incorporated.
Dated: July 17, 2019.
Donna S. Wieting,
Director, Office of Protected Resources, National Marine Fisheries
Service.
[FR Doc. 2019-15516 Filed 7-19-19; 8:45 am]
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