[Federal Register Volume 82, Number 205 (Wednesday, October 25, 2017)]
[Notices]
[Pages 49314-49331]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2017-23132]
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DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
RIN 0648-XF329
Takes of Marine Mammals Incidental to Specified Activities;
Taking Marine Mammals Incidental to a Low-Energy Geophysical Survey in
the Northeastern 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
the Scripps Institution of Oceanography (SIO) to incidentally harass,
by Level A and Level B harassment, marine mammals during a low-energy
marine geophysical survey in the northeastern Pacific Ocean.
DATES: This Authorization is valid from September 22, 2017, through
September 19, 2018.
FOR FURTHER INFORMATION CONTACT: Jordan Carduner, Office of Protected
Resources, NMFS, (301) 427-8401. Electronic copies of the application
and
[[Page 49315]]
supporting documents, as well as a list of the references cited in this
document, may be obtained online at: www.nmfs.noaa.gov/pr/permits/incidental/research.htm. In case of problems accessing these documents,
please call the contact listed above.
SUPPLEMENTARY INFORMATION:
Background
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
authorization is provided to the public for review.
An authorization for incidental takings shall be granted if NMFS
finds that the taking will have a negligible impact on the species or
stock(s), will not have an unmitigable adverse impact on the
availability of the species or stock(s) for subsistence uses (where
relevant), and if the permissible methods of taking and requirements
pertaining to the mitigation, monitoring and reporting of such takings
are set forth.
NMFS has defined ``negligible impact'' in 50 CFR 216.103 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.
The MMPA states that the term ``take'' means to harass, hunt,
capture, kill or attempt to harass, hunt, capture, or kill any marine
mammal.
Except with respect to certain activities not pertinent here, 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).
National Environmental Policy Act
To comply with the National Environmental Policy Act of 1969 (NEPA;
42 U.S.C. 4321 et seq.) and NOAA Administrative Order (NAO) 216-6A,
NMFS must review our proposed action (i.e., the issuance of an
incidental harassment authorization) with respect to potential impacts
on the human environment. Accordingly, NMFS prepared an Environmental
Assessment (EA) to consider the environmental impacts associated with
the issuance of the IHA to SIO. We reviewed all comments submitted in
response to the Federal Register notice for the proposed IHA (82 FR
39276; August 17, 2017) prior to concluding our NEPA process and
deciding whether or not to issue a Finding of No Significant Impact
(FONSI). NMFS concluded that issuance of an IHA to SIO would not
significantly affect the quality of the human environment and prepared
and issued a FONSI in accordance with NEPA and NAO 216-6A. NMFS's EA
and FONSI for this activity are available on our Web site at: http://www.nmfs.noaa.gov/pr/permits/incidental.
Summary of Request
On March 20, 2017, NMFS received a request from SIO for an IHA to
take marine mammals incidental to conducting a low-energy marine
geophysical survey in the northeastern Pacific Ocean. On July 5, 2017,
we deemed SIO's application for authorization to be adequate and
complete. SIO's request is for take of a small number of 27 species of
marine mammals by Level B harassment and Level A harassment. Neither
SIO nor NMFS expects mortality to result from this activity, and,
therefore, an IHA is appropriate. The planned activity is not expected
to exceed one year, hence, we do not expect subsequent MMPA incidental
harassment authorizations would be issued for this particular activity.
Description of Specified Activity
A detailed description of SIO's low-energy geophysical survey is
provided in the Federal Register notice for the proposed IHA (82 FR
39276; August 17, 2017). Since that time, no changes have been made to
the planned activities. Therefore, a detailed description is not
provided here. Please refer to that Federal Register notice for the
description of the specific activity.
Comments and Responses
NMFS published a notice of proposed IHA in the Federal Register on
August 17, 2017 (82 FR 39276). During the 30-day public comment period,
NMFS received a comment letter from the Marine Mammal Commission
(Commission) as well as one comment from a member of the general
public. NMFS has posted the comments online at: http://www.nmfs.noaa.gov/pr/permits/incidental. NMFS addresses any comments
specific to SIO's application related to the statutory and regulatory
requirements or findings that NMFS must make under the MMPA in order to
issue an Authorization. The following is a summary of the public
comments and NMFS' responses.
Comment 1: A comment received from a member of the general public
expressed concern that the survey would result in the deaths of marine
mammals.
Response: NMFS does not anticipate that SIO's survey will result in
the deaths of marine mammals and the authorization does not permit
serious injury or mortality of marine mammals.
Comment 2: The Commission expressed concerns regarding SIO's method
to estimate the extent of the Level A and Level B harassment zones and
the numbers of marine mammal takes. The Commission stated that the
model is not the best available science because it assumes spherical
spreading, a constant sound speed, and no bottom interactions for
surveys in deep water. In light of their concerns, the Commission
recommended that NMFS require SIO, in collaboration with Lamont-Doherty
Earth Observatory of Columbia University (L-DEO) (which performed the
modeling of Level A and Level B harassment zones) to re-estimate the
Level A and Level B harassment zones and associated takes of marine
mammals using 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.
Response: NMFS acknowledges the Commission's concerns about LDEO's
current modeling approach for estimating Level A and Level B harassment
zones and takes. SIO's application (LGL, 2017) and the Federal Register
notice of the proposed IHA (82 FR 39276; August 17, 2017) 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 (LGL, 2017) 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
[[Page 49316]]
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). For
deep water (>1000 m), L-DEO used the deep-water radii obtained from
model results down to a maximum water depth of 2,000 m (Figure 2 and 3
in Appendix H of NSF-USGS 2011); 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 (Fig. 16
in Appendix H of the NSF-USGS 2011).
In 2015, L-DEO 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 Lamont-Doherty (see 80 FR 27635, May 14, 2015,
Table 1). Briefly, the anlysis presented in Crone (2015), specific to
the survey site offshore New Jersey, confirmed that in-situ, site
specific measurements and estimates of 160 dB and 180 dB isopleths
collected by the hydrophone streamer of the R/V Marcus 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 dB and 160 dB zones were approximately 28
percent and 33 percent smaller, 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 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 (greater than
1,000 m; 3280.8 ft) (Diebold et al., 2010). In 2012, L-DEO used a
similar process to model distances to isopleths corresponding to the
isopleths corresponding to Level A and Level B harassment thresholds
for a shallow-water seismic survey in the northeast Pacific Ocean
offshore Washington State. L-DEO conducted the shallow-water survey
using the same airgun configuration planned for the surveys considered
in this IHA (i.e., 6,600 in\3\) 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 bathymetry's role 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 southwest
Pacific 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 in 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.
L-DEO has conveyed to NMFS that additional modeling efforts to
refine the process and conduct comparative analysis may be possible
with the availability of research funds and other resources. Obtaining
research funds is typically accomplished through a competitive process,
including those submitted to U.S. Federal agencies. The use of models
for calculating buffer and exclusion zone radii and for developing take
estimates is not a requirement of the MMPA incidental take
authorization process. Furthermore, NMFS does not provide specific
guidance on model parameters nor prescribe a specific model for
applicants as part of the MMPA incidental take authorization process at
this time, although we do review methods to ensure adequate for
prediction of 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 3: The Commission expressed concern that the method used to
estimate the numbers of takes, which summed fractions of takes for each
species across project days, does not account for and negates the
intent of NMFS' 24-hour reset policy.
NMFS Response: We appreciate the Commission's ongoing concern in
this matter. Calculating predicted takes is not an exact science and
there are arguments for taking different mathematical approaches in
different situations, and for making qualitative adjustments in other
situations. We believe, however, that the methodology used for take
calculation in this IHA remains appropriate and is not at odds with the
24-hour reset policy the Commission references.
Comment 4: The Commission expressed concern that information was
missing in NMFS's Federal Register notice of proposed IHA (82 FR 39276;
August 17, 2017) and SIO's application,
[[Page 49317]]
including operating frequency of the multibeam echosounder (MBES) and
sub-bottom profiler (SBP) and information regarding densities, Level A
daily ensonified areas, and number of days of activities that informed
NMFS's analysis.
NMFS Response: We appreciate the Commission pointing out the
deficiencies in the Federal Register notice of proposed IHA (82 FR
39276; August 17, 2017). In response to the Commisison's concerns we
have done the following, as recommended by the Commission: (1) Used the
Dall's porpoise density derived from Beaufort sea states (BSS) of 0-5
rather than 0-3; (2) ensured that pinniped densities are based on the
best available information; and (3) ensured the estimated numbers of
Level A and B harassment takes are correct based on the relevant
densities, daily ensonified areas, and number of days of activities
(Table 8). The MBES will operate at 12 kilohertz (kHz) and the SBP will
operate at 3.5 kHz.
Description of Marine Mammals in the Area of Specified Activities
Section 4 of the IHA application summarizes available information
regarding status and trends, distribution and habitat preferences, and
behavior and life history, of the potentially affected species.
Additional information regarding population trends and threats may be
found in NMFS' Stock Assessment Reports (SAR; www.nmfs.noaa.gov/pr/sars/), and more general information about these species (e.g.,
physical and behavioral descriptions) may be found on NMFS' Web site
(www.nmfs.noaa.gov/pr/species/mammals/).
Table 1 lists all species with expected potential for occurrence in
the northeastern Pacific Ocean and summarizes information related to
the population or stock, including regulatory status under the MMPA and
Endangered Species Act (ESA) and potential biological removal (PBR),
where known. For taxonomy, we follow Committee on Taxonomy (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' 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' stock abundance estimates for most species represent the total
estimate of individuals within the geographic area, if known, that
comprises that stock. For some species, this geographic area may extend
beyond U.S. waters. All managed stocks in this region are assessed in
NMFS' U.S. Pacific SARs (e.g., Carretta et al., 2017). All values
presented in Table 1 are the most recent available at the time of
publication and are available in the 2017 SARs (Carretta et al., 2017),
available online at: www.nmfs.noaa.gov/pr/sars, except where noted
otherwise.
Table 1--Marine Mammals That Could Occur in the Project Area
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Stock abundance
ESA/MMPA \2\ (CV, Nmin, Relative
Species Stock status; most recent PBR \4\ Occurrence in
strategic (Y/N) abundance project area
\1\ survey) \3\
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Order Cetartiodactyla--Cetacea--Superfamily Mysticeti (baleen whales)
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Family: Balaenopteridae
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North Pacific right whale \5\ Eastern North E/D; Y 31.............. 0.1 Rare.
(Eubalaena japonica). Pacific.
Gray whale \5\ (Eschrichtius Eastern North -/-; N 20,990 (0.05; 3.1 Common in
robustus). Pacific. 20,125; 2011). nearshore
areas, rare
elsewhere.
Humpback whale \6\ (Megaptera California/ E/T/D; N 1,918 (0.03; 11 Common in
novaeangliae). Oregon/ 1,876; 2014). nearshore
Washington. areas, rare
elsewhere.
Minke whale (Balaenoptera California/ -/-; N 636 (0.72; 369; 3.5 Rare.
acutorostrata). Oregon/ 2014).
Washington.
Sei whale (Balaenoptera Eastern N E/D; Y 519 (0.4; 374; 0.75 Rare.
borealis). Pacific. 2014).
Fin whale (Balaenoptera California/ E/D; Y 9,029 (0.12; 81 Common.
physalus). Oregon/ 8,127; 2014).
Washington.
Blue whale (Balaenoptera Eastern N E/D; Y 1,647 (0.07; 2.3 Rare.
musculus). Pacific. 1,551; 2011).
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Order Cetartiodactyla--Cetacea--Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
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Family: Physeteridae
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Sperm whale (Physeter California/ E/D; Y 2,106 (0.58; 2.7 Common.
macrocephalus). Oregon/ 1,332; 2014).
Washington.
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Order Cetartiodactyla--Cetacea--Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
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Family: Kogiidae
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Pygmy sperm whale (Kogia California/ -/-; N 4,111 (1.12; 19 Rare.
breviceps). Oregon/ 1,924; 2014).
Washington.
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[[Page 49318]]
Dwarf sperm whale (Kogia sima) California/ -/-; N unknown Undet. Rare.
Oregon/ (unknown;
Washington. unknown; 2014).
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Order Cetartiodactyla--Cetacea--Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
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Family: delphinidae
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Killer whale (Orcinus orca)... West coast -/-; N 243 (n/a; 243; 2.4 Rare.
transient. 2009).
Eastern North -/-; N 240 (0.49; 162; 1.6 Rare.
Pacific 2014).
offshore.
False killer whale \7\ Hawaii Pelagic.. -/-; N 1,540 (0.66; 9.3 Rare.
(Pseudorca crassidens). 928; 2010).
Short-finned pilot whale California/ -/-; N 836 (0.79; 466; 4.5 Rare.
(Globicephala macrorhynchus). Oregon/ 2014).
Washington.
Harbor porpoise (Phocoena Northern Oregon/ -/-; N 21,487 (0.44; 151 Abundant.
phocoena). Washington 15,123; 2011).
Coast.
Northern -/-; N 35,769 (0.52; 475 Abundant.
California/ 23,749; 2011).
Southern Oregon.
Dall's porpoise (Phocoena California/ -/-; N 25,750 (0.45; 172 Abundant.
dalli). Oregon/ 17,954; 2014).
Washington.
Bottlenose dolphin (Tursiops California/ -/-; N 1,924 (0.54; 11 Rare.
truncatus). Oregon/ 1,255; 2014).
Washington
Offshore.
Striped dolphin (Stenella California/ -/-; N 29,211 (0.2; 238 Rare.
coeruleoala). Oregon/ 24,782; 2014).
Washington.
Risso's dolphin (Grampus California/ -/-; N 6,336 (0.32; 46 Common.
griseus). Oregon/ 4,817; 2014).
Washington.
Short-beaked common dolphin California/ -; N 969,861 (0.17; 8,393 Common.
(Delphinus delphis). Oregon/ 839,325; 2014).
Washington.
Pacific white-sided dolphin California/ -; N 26,814 (0.28; 191 Abundant.
(Lagenorhynchus obliquidens). Oregon/ 21,195; 2014).
Washington.
Northern right whale dolphin California/ -; N 26,556 (0.44; 179 Common.
(Lissodelphis borealis). Oregon/ 18,608; 2014).
Washington.
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Order Cetartiodactyla--Cetacea--Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
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Family: Ziphiidae
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Cuvier's beaked whale (Ziphius California/ -/-; N 6,590 (0.55; 45 Common.
cavirostris). Oregon/ 4,481; 2008).
Washington.
Baird's beaked whale California/ -; N 847 (0.81; 466; 4.7 Common.
(Berardius bairdii). Oregon/ 2008).
Washington.
Mesoplodont beaked whales \8\. California/ -/-; N 694 (0.65; 389; 3.9 Rare.
Oregon/ 2008).
Washington.
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Order Carnivora--Superfamily Pinnipedia
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Family: Otariidae (eared seals and sea lions)
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California sea lion (Zalophus U.S............. -; N 296,750 (n/a; 9,200 Rare.
californianus). 153,337; 2011).
Steller sea lion (Eumetopias Eastern U.S..... -; N 41,638 (n/a; 2,498 Common in
jubatus). 41,638; 2015). nearshore
areas, rare
elsewhere.
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Family: Phocidae (earless seals)
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Harbor seal \9\ (Phoca Oregon/ -; N 24,732 (unk; Unknown Common in
vitulina). Washington unk; n/a). nearshore
Coast. areas, rare
elsewhere.
Northern elephant seal California -; N 179,000 (n/a; 4,882 Common in
(Mirounga angustirostris). breeding. 81,368; 2010). nearshore
areas, rare
elsewhere.
Northern fur seal (Callorhinus California...... -; N 14,050 (n/a; 451 Common in
ursinus). 7,524; 2013). nearshore
areas, rare
elsewhere.
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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 (see footnote
3) 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\ Abundance estimates from Carretta et al. (2017) unless otherwise noted.
[[Page 49319]]
\3\ CV is coefficient of variation; Nmin is the minimum estimate of stock abundance. In some cases, CV is not
applicable. For certain stocks, abundance estimates are actual counts of animals and there is no associated
CV. The most recent abundance survey that is reflected in the abundance estimate is presented; there may be
more recent surveys that have not yet been incorporated into the estimate.
\4\ Potential biological removal (PBR), 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 size (OSP).
\5\ Values for gray whale and North Pacific right whale are from Muto et al. (2016).
\6\ Humpback whales in the survey area could originate from either the ESA threatened Mexico DPS or from the ESA
endangered Central America DPS.
\7\ NMFS does not have a defined stock for false killer whales off the West Coast of the U.S. as they are
considered uncommon visitors to the area; any false killer whales observed off the West Coast of the U.S.
would likely be part of the eastern North Pacific population. Of the stocks defined by NMFS, the Hawaii
Pelagic stock is the most likely to include individuals in the eastern North Pacific population.
\8\ Includes the following species: Blainville's beaked whale (M. densirostris), Perrin's beaked whale (M.
perrini), Lesser beaked whale (M. peruvianus), Stejneger's beaked whale (M. stejnegeri), Gingko-toothed beaked
whale (M. gingkodens), and Hubbs' beaked whale (M. carlhubbsi).
\9\ The most recent abundance estimate is from 1999. This is the best available information, but because this
abundance estimate is >8 years old, there is no current estimate of abundance available for this stock.
All species that could potentially occur in the planned survey area
are included in Table 1. However, as described below, the spatial
occurrence of the North Pacific right whale and dwarf sperm whale are
such that take is not expected to occur for these species. The North
Pacific right whale is one of the most endangered species of whale in
the world (Carretta et al., 2017). Only 82 sightings of right whales in
the entire eastern North Pacific were reported from 1962 to 1999, with
the majority of these occurring in the Bering Sea and adjacent areas of
the Aleutian Islands (Brownell et al. 2001). Most sightings in the past
20 years have occurred in the southeastern Bering Sea, with a few in
the Gulf of Alaska (Wade et al. 2011). Despite many miles of systematic
aerial and ship-based surveys for marine mammals off the coasts of
Washington, Oregon and California over several years, only seven
documented sightings of right whales were made from 1990 to 2000 (Waite
et al. 2003). Because of the small population size and the fact that
North Pacific right whales spend the summer feeding in high latitudes,
the likelihood that the planned survey would encounter a North Pacific
right whale is discountable. Along the U.S. west coast, no at-sea
sightings of dwarf sperm whales have ever been reported despite
numerous vessel surveys of this region (Barlow 1995; Barlow and
Gerrodette 1996; Barlow and Forney 2007; Forney 2007; Barlow 2010,
Barlow 2016). Therefore, based on the best available information, we
believe the likelihood of the survey encountering a dwarf sperm whale
is discountable. SIO requested authorization for the incidental take of
dwarf sperm whales (the request was for a combined two takes of pygmy
and/or dwarf sperm whales). However as we have determined the
likelihood of take of dwarf sperm whales is discountable, we do not
authorize take of dwarf sperm whales. Thus, the North Pacific right
whale and dwarf sperm whale are not discussed further in this document.
A detailed description of the of the species likely to be affected
by SIO's survey, 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 (82 FR
39276; August 17, 2017); since that time, we are not aware of any
changes in the status of these species and stocks; therefore, detailed
descriptions are not provided here. Please refer to that Federal
Register notice for these descriptions. Please also refer to NMFS' Web
site for generalized species accounts: www.nmfs.noaa.gov/pr/species/mammals/.
Potential Effects of Specified Activities on Marine Mammals and Their
Habitat
The effects of underwater noise from marine geophysical survey
activities have the potential to result in behavioral harassment and,
in a limited number of instances, auditory injury (PTS) of marine
mammals in the vicinity of the action area. The Federal Register notice
of proposed IHA (82 FR 39276; August 17, 2017) included a discussion of
the effects of anthropogenic noise on marine mammals and their habitat,
therefore that information is not repeated here; please refer to that
Federal Register notice for that information. No instances of serious
injury or mortality are expected as a result of SIO's survey
activities.
Estimated Take
This section provides an estimate of the number of incidental takes
authorized through this IHA, which will inform both NMFS' consideration
of whether the number of takes is ``small'' and the negligible impact
determination.
Harassment is the only type of take expected to result from these
activities. Except with respect to certain activities not pertinent
here, section 3(18) of the MMPA defines ``harassment'' as: Any act of
pursuit, torment, or annoyance which (i) has the potential to injure a
marine mammal or marine mammal stock in the wild (Level A harassment);
or (ii) has the potential to disturb a marine mammal or marine mammal
stock in the wild by causing disruption of behavioral patterns,
including, but not limited to, migration, breathing, nursing, breeding,
feeding, or sheltering (Level B harassment).
Authorized takes are primarily by Level B harassment, as use of the
seismic airguns have the potential to result in disruption of
behavioral patterns for individual marine mammals. There is also some
potential for auditory injury (Level A harassment) to result, primarily
for high frequency cetaceans and phocid pinnipeds. Auditory injury is
unlikely to occur for low- and mid-frequency species given very small
modeled zones of injury for those species. The mitigation and
monitoring measures are expected to minimize the severity of such
taking to the extent practicable. As described previously, no mortality
is anticipated or authorized for this activity. Below we describe how
the take is estimated.
Described in the most basic way, 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. Below, we describe these
components in more detail and present the exposure estimate and
associated numbers of take authorized.
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
[[Page 49320]]
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. 2011). Based on the best available science 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 to fall under Level B
harassment when exposed to underwater anthropogenic noise above
received levels of 120 decibedl (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. SIO'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 (NMFS 2016) 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). The
Technical Guidance identifies the received levels, or thresholds, above
which individual marine mammals are predicted to experience changes in
their hearing sensitivity for all underwater anthropogenic sound
sources, reflects the best available science, and better predicts the
potential for auditory injury than does NMFS' historical criteria.
These thresholds were developed by compiling and synthesizing the
best available science and soliciting input multiple times from both
the public and peer reviewers to inform the final product, and are
provided in Table 3 below. The references, analysis, and methodology
used in the development of the thresholds are described in NMFS 2016
Technical Guidance, which may be accessed at: www.nmfs.noaa.gov/pr/acoustics/guidelines.htm. As described above, SIO's planned activity
includes the use of intermittent and impulsive seismic sources.
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 (2016) described generalized hearing
ranges for these marine mammal hearing groups (Table 2). Generalized
hearing ranges were chosen based on the approximately 65 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. The functional groups and the associated frequencies
are indicated below (note that these frequency ranges correspond to the
range for the composite group, with the entire range not necessarily
reflecting the capabilities of every species within that group):
Low-frequency cetaceans (mysticetes): Generalized hearing
is estimated to occur between approximately 7 hertz (Hz) and 35 kHz,
with best hearing estimated to be from 100 Hz to 8 kHz;
Mid-frequency cetaceans (larger toothed whales, beaked
whales, and most delphinids): Generalized hearing is estimated to occur
between approximately 150 Hz and 160 kHz, with best hearing from 10 to
less than 100 kHz;
High-frequency cetaceans (porpoises, river dolphins, and
members of the genera Kogia and Cephalorhynchus; including two members
of the genus Lagenorhynchus, on the basis of recent echolocation data
and genetic data): Generalized hearing is estimated to occur between
approximately 275 Hz and 160 kHz.
Pinnipeds in water; Phocidae (true seals): Generalized
hearing is estimated to occur between approximately 50 Hz to 86 kHz,
with best hearing between 1-50 kHz;
Pinnipeds in water; Otariidae (eared seals): Generalized
hearing is estimated to occur between 60 Hz and 39 kHz, with best
hearing between 2-48 kHz.
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).
Table 2--Marine Functional Mammal Hearing Groups and Their Generalized
Hearing Ranges
------------------------------------------------------------------------
Hearing group Generalized hearing range *
------------------------------------------------------------------------
Low frequency (LF) cetaceans (baleen 7Hz to 35 kHz.
whales).
Mid-frequency (MF) cetaceans (dolphins, 150 Hz to 160 kHz.
toothed whales, beaked whales,
bottlenose whales).
High-frequency (HF) cetaceans (true 275 Hz to 160 kHz.
porpoises, Kogia, river dolphins,
cephalorhynchid, Lagenorhynchus cruciger
and L. australis).
Phocid pinnipeds (PW) (underwater) (true 50 Hz to 86 kHz.
seals).
Otariid pinnipeds (OW) (underwater) (sea 60 Hz to 39 kHz.
lions and fur seals).
------------------------------------------------------------------------
* Represents the generalized hearing range for the entire group as a
composite (i.e., all species within the group), where individual
species' hearing ranges are typically not as broad. Generalized
hearing range chosen based on ~65 dB threshold from normalized
composite audiogram, with the exception for lower limits for LF
cetaceans (Southall et al., 2007) and PW pinniped (approximation).
[[Page 49321]]
For more detail concerning these groups and associated frequency
ranges, please see NMFS (2016) for a review of available information.
Twenty four marine mammal species (all cetaceans) 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, 6 are
classified as low-frequency cetaceans (i.e., all mysticete species), 16
are classified as mid-frequency cetaceans (i.e., all delphinid and
ziphiid species and the sperm whale), and 2 are classified as high-
frequency cetaceans (i.e., Kogia spp.).
Table 3--Thresholds Identifying the Onset of Permanent Threshold Shift
in Marine Mammals
------------------------------------------------------------------------
PTS onset thresholds
Hearing group ------------------------------------------
Impulsive * Non-impulsive
------------------------------------------------------------------------
Low-Frequency (LF) Cetaceans. Lpk,flat: 219 LE,LF,24h: 199 dB.
dB, LE,LF,24h:
183 dB.
Mid-Frequency (MF) Cetaceans. Lpk,flat: 230 LE,MF,24h: 198 dB.
dB, LE,MF,24h:
185 dB.
High-Frequency (HF) Cetaceans Lpk,flat: 202 LE,HF,24h: 173 dB.
dB, LE,HF,24h:
155 dB.
Phocid Pinnipeds Lpk,flat: 218 LE,PW,24h: 201 dB.
(PW)(Underwater). dB, LE,PW,24h:
185 dB.
Otariid Pinnipeds (OW) Lpk,flat: 232 LE,OW,24h: 219 dB.
(Underwater). dB, LE,OW,24h:
203 dB.
------------------------------------------------------------------------
Note: * Dual metric acoustic thresholds for impulsive sounds: Use
whichever results in the largest isopleth for calculating PTS onset.
If a non-impulsive sound has the potential of exceeding the peak sound
pressure level thresholds associated with impulsive sounds, these
thresholds should also be considered.
Note: Peak sound pressure (Lpk) has a reference value of 1 [mu]Pa, and
cumulative sound exposure level (LE) has a reference value of
1[mu]Pa2s. In this Table, thresholds are abbreviated to reflect
American National Standards Institute standards (ANSI 2013). However,
peak sound pressure is defined by ANSI as incorporating frequency
weighting, which is not the intent for this Technical Guidance. Hence,
the subscript ``flat'' is being included to indicate peak sound
pressure should be flat weighted or unweighted within the generalized
hearing range. The subscript associated with cumulative sound exposure
level thresholds indicates the designated marine mammal auditory
weighting function (LF, MF, and HF cetaceans, and PW and OW pinnipeds)
and that the recommended accumulation period is 24 hours. The
cumulative sound exposure level thresholds could be exceeded in a
multitude of ways (i.e., varying exposure levels and durations, duty
cycle). When possible, it is valuable for action proponents to
indicate the conditions under which these acoustic thresholds will be
exceeded.
Ensonified Area
Here, we describe operational and environmental parameters of the
activity that will feed into estimating the area ensonified above the
acoustic thresholds.
The planned survey would entail the use of a 2-airgun array with a
total discharge of 90 cubic inches (in\3\) at a tow depth of 3 meters
(m). The distance to the predicted isopleth corresponding to the
threshold for Level B harassment (160 dB re 1 [mu]Pa) was calculated
based on results of modeling performed by LDEO. Received sound levels
were predicted by LDEO's model (Diebold et al. 2010) as a function of
distance from the airgun array. The LDEO modeling approach 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 a 36-airgun array at
a tow depth of 6 m have been reported in deep water (~1,600 m),
intermediate water depth on the slope (~600-1100 m), and shallow water
(~50 m) in the Gulf of Mexico in 2007-2008 (Tolstoy et al. 2009;
Diebold et al. 2010). The estimated distances to the Level B harassment
isopleth for the Revelle airgun array are shown in Table 4.
Table 4--Predicted Radial Distances From R/V Revelle 90 in\3\ Seismic
Source to Isopleth Corresponding to Level B Harassment Threshold
------------------------------------------------------------------------
Predicted distance to
Water depth threshold (160 dB re 1
[mu]Pa)
------------------------------------------------------------------------
>1000 m................................... 448 m.
100-1,000 m............................... 672 m.
------------------------------------------------------------------------
For modeling of radial distances to predicted isopleths
corresponding to harassment thresholds in deep water (>1,000 m), LDEO
used the deep-water radii for various Sound Exposure Levels obtained
from LDEO model results down to a maximum water depth of 2,000 m (see
Figure 2 in the IHA application). Radial distances to predicted
isopleths corresponding to harassment thresholds in intermediate water
depths (100-1,000 m) were derived by LDEO from the deep-water distances
by applying a correction factor (multiplication) of 1.5, such that
observed levels at very near offsets fall below the corrected
mitigation curve (Fig. 16 in Appendix H of NSF-USGS 2011). LDEO's
modeling methodology is described in greater detail in the IHA
application (LGL 2017) and we refer the reader to that document rather
than repeating it here.
Predicted distances to Level A harassment isopleths, which vary
based on marine mammal functional hearing groups (Table 2), were
calculated based on modeling performed by LDEO using the Nucleus
software program and the NMFS User Spreadsheet, described below. The
updated acoustic thresholds for impulsive sounds (such as airguns)
contained in the Technical Guidance (NMFS 2016) were presented as dual
metric acoustic thresholds using both cumulative sound exposure level
(SELcum) and peak sound pressure level (SPL) metrics. 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 Revelle
airgun array were derived from calculating the modified farfield
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
[[Page 49322]]
kilometers (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 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. Though the array effect is not expected to be as pronounced in
the case of a 2-airgun array as it would be with a larger airgun array,
the modified farfield method is considered more appropriate than use of
the theoretical farfield signature.
Table 5--Modeled Source Levels Using Modified Farfield Method for R/V
Revelle 90-in\3\ Airgun Array
------------------------------------------------------------------------
Functional hearing group Peak SPLflat SELcum
------------------------------------------------------------------------
Low frequency cetaceans 232.805 dB 206.0165 dB.
(Lpk,flat: 219 dB; LE,LF,24h:
183 dB).
Mid frequency cetaceans 229.89 dB 205.9638 dB.
(Lpk,flat: 230 dB; LE,MF,24h:
185 dB).
High frequency cetaceans 232.867 dB 206.384 dB.
(Lpk,flat: 202 dB; LE,HF,24h:
155 dB).
Phocid Pinnipeds (Underwater) 232.356 dB 205.9638 dB.
(Lpk,flat: 218 dB; LE,HF,24h:
185 dB).
Otariid Pinnipeds (Underwater) 224.7897 dB 206.806 dB.
(Lpk,flat: 232 dB; LE,HF,24h:
203 dB).
------------------------------------------------------------------------
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 Revelle's airgun array (modeled in 1
Hz bands) was used to make adjustments (dB) to the unweighted spectrum
levels, by frequency, according to the weighting functions for each
relevant marine mammal hearing group. These adjusted/weighted spectrum
levels were then converted to pressures ([mu]Pa) in order to integrate
them over the entire 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, a source velocity of 2.57 m/second, and shot interval of
7.78 seconds (LGL 2017), potential radial distances to auditory injury
zones were then calculated for SELcum thresholds. Inputs to
the User Spreadsheet are shown in Table 5. Outputs from the User
Spreadsheet in the form of estimated distances to Level A harassment
isopleths are shown in Table 6. As described above, the larger distance
of the dual criteria (SELcum or Peak SPLflat) is
used for estimating takes by Level A harassment. The weighting
functions used are shown in Table 3 of the IHA application.
Table 6--Modeled Radial Distances (m) From R/V Revelle 90-in\3\ Airgun
Array to Isopleths Corresponding to Level A Harassment thresholds
------------------------------------------------------------------------
Functional hearing group (Level A Peak SPLflat
harassment thresholds) SELcum
------------------------------------------------------------------------
Low frequency cetaceans (Lpk,flat: 219 4.9 7.9
dB; LE,LF,24h: 183 dB).................
Mid frequency cetaceans (Lpk,flat: 230 1.0 0
dB; LE,MF,24h: 185 dB).................
High frequency cetaceans (Lpk,flat: 202 34.9 0
dB; LE,HF,24h: 155 dB).................
Phocid Pinnipeds (Underwater) (Lpk,flat: 5.2 0.1
218 dB; LE,HF,24h: 185 dB).............
Otariid Pinnipeds (Underwater) 0.4 0
(Lpk,flat: 232 dB; LE,HF,24h: 203 dB)..
------------------------------------------------------------------------
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
take. However, these tools offer the best way to predict appropriate
isopleths when more sophisticated 3D 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.
The best available scientific information was considered in
conducting marine mammal exposure estimates (the basis for estimating
take). For most cetacean species, densities calculated by Barlow (2016)
were used. These represent the most comprehensive and recent density
data available for cetacean species in slope and offshore waters of
Oregon and Washington and are based on data collected via NMFS
Southwest Fisheries Science Center (SWFSC) ship-based surveys in 1991,
1993, 1996, 2001, 2005, 2008, and 2014. The surveys were conducted up
to ~556 km from shore from June or August to November or December. The
densities from NMFS SWFSC vessel-based surveys were corrected by the
authors for both
[[Page 49323]]
trackline detection probability and availability bias. Trackline
detection probability bias is associated with diminishing sightability
with increasing lateral distance from the trackline and is measured by
f(0). Availability bias refers to the fact that there is less than 100
percent probability of sighting an animal that is present along the
survey trackline, and it is measured by g(0). Abundance and density
were not estimated for gray whales or harbor porpoises in the NMFS
SWFSC surveys because their inshore habitats were inadequately covered
in those studies. Gray whale density is derived from the abundance of
gray whales that remain between Oregon and British Columbia in summer
(updated based on abundance calculated by Calambokidis et al. 2014) and
the area out to 43 km from shore, using the U.S. Navy (2010) method.
Harbor porpoise densities are based on data from aerial line-transect
surveys during 2007-2012 for the Northern Oregon/Washington Coast stock
(Forney et al. 2014).
Systematic, offshore, at-sea survey data for pinnipeds are more
limited than those for cetaceans. Densities for pinnipeds were
calculated as the estimated number of animals at sea divided by the
area encompassing their range. Densities for the Steller sea lion,
California sea lion, northern elephant seal, and northern fur seal were
calculated using the methods in U.S. Navy (2010) with updated abundance
estimates from Carretta et al. (2016) and Muto et al. (2016), when
appropriate. For the harbor seal, densities were calculated using the
population estimate for the Oregon/Washington Coastal stock and the
range for that stock from Carretta et al. (2016).
In the Federal Register notice of the proposed IHA (82 FR 39276;
August 17, 2017), areas encompassing the ranges of pinniped species,
which were used to estimate pinniped densities, were based on areas
reported in U.S. Navy (2010). However, after publication of the notice
of the proposed IHA, the Commission noted in their comment letter that
the best available data on areas encompassing the ranges of pinniped
species in the project area is presented in U.S. Navy (2014). We have
reviewed U.S. Navy (2014) and have revised densities in the final IHA
from those shown in the proposed IHA accordingly, to reflect the best
available information on areas encompassing the ranges of pinniped
species. The estimates of the numbers of animals at sea that were used
to estimate densities in the proposed IHA remains the best available
information for all five pinniped species expected to occur in the
survey area; thus, in revising estimated densities we used the updated
areas from U.S. Navy 2014 (when updated areas were available), and the
same estimates of the numbers of animals at sea as those that were used
to estimate density in the proposed IHA. For three species (Steller sea
lion, northern elephant seal, and northern fur seal) the areas reported
in U.S. Navy (2014) were the same as those in U.S. Navy (2010);
therefore, there was no need to revise densities for these species. For
harbor seal and California sea lion, areas reported in U.S. Navy (2014)
were different than those reported in U.S. Navy (2010); therefore, we
have revised density estimates of these two species to reflect the best
available information. Note that correction factors were applied in
some cases in the calculations of density estimates for pinnipeds (see
footnotes in Table 8).
There is some uncertainty related to the estimated density data and
the assumptions used in their calculations, as with all density data
estimates. However, the approach used is based on the best available
data.
Take Calculation and Estimation
Here we describe how the information provided above is brought
together to produce a quantitative take estimate. In order to estimate
the number of marine mammals predicted to be exposed to sound levels
that would result in Level A harassment or Level B harassment, radial
distances from the airgun array to predicted isopleths corresponding to
the Level A harassment threshold and Level B harassment threshold are
calculated, as described above. Those radial distances are then used to
calculate the area(s) around the airgun array predicted to be
ensonified to sound levels that exceed the Level A harassment and Level
B harassment thresholds. The area estimated to be ensonified to those
thresholds in a single day of the survey is then calculated (Table 7),
based on the areas predicted to be ensonified around the array and the
estimated trackline distance traveled per day. This number is then
multiplied by the number of survey days (i.e., 5). The product is then
multiplied by 1.25 to account for the additional 25 percent
contingency, as described above. This results in an estimate of the
total areas in square kilometers (km\2\) expected to be ensonified to
the Level A harassment and Level B harassment thresholds (Table 7). For
purposes of Level B take calculations, areas estimated to be ensonified
to Level A harassment thresholds are subtracted from total areas
estimated to be ensonified to Level B harassment thresholds in order to
avoid double counting the animals taken (i.e., if an animal is taken by
Level A harassment, it is not also counted as taken by Level B
harassment). The marine mammals predicted to occur within these
respective areas, based on estimated densities, are assumed to be
incidentally taken. Areas estimated to be ensonified to the Level B
harassment threshold for the planned survey are shown in Table 7.
Estimated takes for all marine mammal species are shown in Table 8.
Table 7-- Areas (km\2\) Estimated To Be Ensonified to Level A and Level B Harassment Thresholds Over the
Duration of the Survey
----------------------------------------------------------------------------------------------------------------
Level A harassment threshold \1\
Level B --------------------------------------------------------------------------------------------------
harassment All marine Low frequency Mid frequency High frequency Otariid Phocid
threshold mammals cetaceans cetaceans cetaceans Pinnipeds Pinnipeds
------------------------------------------------------------------------------------------------------- -----------
1,276.25 21.1 2.6 96.2 1.2 13.9
----------------------------------------------------------------------------------------------------------------
Note: Estimated areas based on five survey days and include additional 25 percent contingency (effectively
resulting in 6.25 survey days). Level A ensonified areas are estimated based on the greater of the distances
calculated to Level A isopleths using dual criteria (SELcum and peakSPL).
Take estimates for Dall's porpoise and harbor porpoise have been
been revised from those reflected in the Federal Register notice of
proposed IHA (82 FR 39276; August 17, 2017). For Dall's porpoise, we
have adopted the Commission's suggestion that the take estimate should
be based on the density for the species that was derived in BSS
[[Page 49324]]
of 0-5 (58.3 animals per km\2\) versus the density that was derived in
BSS of 0-3 (54.4 animals per km\2\) which was used in the take stimate
shown in the proposed IHA, based on the fact that previous geophysical
surveys in waters of northern California, Oregon, and Washington have
occurred in BSSs of 0-7 during the same season. Additionally, for
species for which Level A take is being authorized, the Commission
correctly noted that Level A estimates should be subtracted from Level
B estimates when calculating the total number of authorized takes (to
avoid double counting the animals taken by Level A harassment, as
described above); this step had mistakenly not been performed for the
take estimates reflected in the proposed IHA. These revisions resulted
in a revised estimate of 69 Level B takes (versus 68 as shown in the
proposed IHA) and a revised estimate of 74 total takes (versus 73 as
shown in the proposed IHA). Harbor porpoise takes were recalculated due
to a mathematical error in the take estimate reflected in the proposed
IHA, and were also revised to avoid double counting of takes (as
described for Dall's porpoise above). This resulted in a revised
estimate of 552 Level B takes (versus 582) and a revised estimate of
596 total takes (versus 627).
Take estimates for harbor porpoise and California sea lion have
been also been revised based on use of revised density estimates for
these species as described above. As noted above, in response to
concerns raised by the Commission, density estimates used to estimate
take for harbor seal and California sea lion have been revised to
reflect the best available information on the range of those species
(represented by U.S. Navy (2014)). As areas representing the range of
the species for harbor seal and California sea lion reported in U.S.
Navy (2014) were greater than those reported in U.S. Navy (2010), and
estimates of the numbers of animals at sea remained the same for both
species, this resulted in lower estimated densities, and lower
estimated take numbers, for both species. For Caifornia sea lion,
density was revised from 283.3 animals per 1,000 km\2\ to 33.3 animals
per 1,000 km\2\. This resulted in a revised take estimate of 43 takes
by Level B harassment (versus the previous estimate of 362 takes by
Level B harassment) (Table 8). For harbor seal, density was revised
from 292 animals per 1,000 km\2\ to 279 animals per 1,000 km\2\. This
resulted in a revised take estimate of 356 takes by Level B harassment;
however, as Level A estimates are subtracted from Level B estimates
when calculating the total number of authorized takes (to avoid double
counting the animals taken by Level A harassment, as described above)
the revised take estimate for harbor seals is 352 takes by Level B
harassment and 4 takes by Level A harassment (versus the previous
estimate of 367 takes by Level B harassment) (Table 8).
Table 8--Numbers of Potential Incidental Take of Marine Mammals Authorized
----------------------------------------------------------------------------------------------------------------
Total
authorized
Estimated Level A and
Density (#/ and Estimated Authorized Total Level B
Species 1,000 authorized Level B Level B authorized takes as a
km\2\) Level A takes takes takes percentage
takes of
population
----------------------------------------------------------------------------------------------------------------
Gray whale........................ 2.6 0 4 4 4 <0.1
Humpback whale.................... 2.1 0 3 3 3 0.2
Minke whale....................... 1.3 0 2 2 2 0.3
Sei whale \1\..................... 0.4 0 1 2 2 0.4
Fin whale......................... 4.2 0 6 6 6 <0.1
Blue whale........................ 0.3 0 1 1 1 <0.1
Sperm whale \1\................... 0.9 0 2 6 6 0.3
Pygmy sperm whale................. 1.6 0 2 2 2 <0.1
Killer whale \1\.................. 0.9 0 2 8 8
West coast transient stock........ ........... ........... ........... ........... ........... 3.3
Eastern No. Pacific offshore stock ........... ........... ........... ........... ........... 3.3
False killer whale \1\............ 0 0 0 5 5 0.3
Short-finned pilot whale \1\...... 0.2 0 1 18 18 2.2
Harbor porpoise................... 467.0 44 552 552 596
No.California/So. Oregon stock.... ........... ........... ........... ........... ........... 1.7
Northern Oregon/Washington coast ........... ........... ........... ........... ........... 2.7
stock............................
Dall's porpoise................... 58.3 5 69 69 74 0.3
Bottlenose dolphin \1\............ 0 0 0 13 13 6.8
Striped dolphin \1\............... 7.7 0 10 109 109 3.7
Risso's dolphin \1\............... 11.8 0 16 28 28 4.4
Short-beaked common dolphin \1\... 69.2 0 89 286 286 <0.1
Pacific white sided dolphin \1\... 40.7 0 52 62 62 2.3
Northern right whale dolphin \1\.. 46.4 0 60 63 63 2.5
Cuvier's beaked whale............. 2.8 0 4 4 4 <0.1
Baird's beaked whale.............. 10.7 0 14 14 14 1.7
Mesoplodont beaked whales \2\..... 1.2 0 2 2 2 2.9
Northern fur seal \3\............. 83.4 0 107 107 107 0.8
California sea lion \4\........... 33.3 0 43 43 43 <0.1
Steller sea lion \5\.............. 15.0 0 20 20 20 <0.1
Harbor seal \6\................... 292.3 4 352 352 356 1.4
Northern elephant seal \7\........ 83.1 1 105 105 106 <0.1
----------------------------------------------------------------------------------------------------------------
\1\ The number of authorized takes (Level B harassment only) for these species has been increased from the
estimated take to mean group size (as reported in Barlow (2016)).
\2\ May be any of the following: Blainville's beaked whale, Perrin's beaked whale, Lesser beaked whale,
Stejneger's beaked whale, Gingko-toothed beaked whale, or Hubb's beaked whale.
[[Page 49325]]
\3\ Estimated density based on abundance of Eastern Pacific stock from Muto et al. (2016) plus California stock
from Carretta et al. (2017) subtracting pups for Eastern Pacific stock (Muto et al. 2016) and subtracting pups
for San Miguel Island (Carretta et al. 2017) as it was assumed that pups would not be at sea during the
survey. Area representing range of the stock is 6,165,000 km\2\ (U.S. Navy 2014).
\4\ Estimated density based on abundance estimate from Jeffries et al. (2000). Area representing range of the
stock is 150,000 km\2\ (U.S. Navy 2014).
\5\ Estimated density based on abundance estimate from Muto et al. (2016); abundance estimate was multiplied by
0.25, as an estimate of the percentage of the population at sea (Bonnell and Bowlby 1992; U.S. Navy 2014).
Area representing range of the stock is 1,244,000 km\2\ (U.S. Navy 2014).
\6\ Estimated density based on abundance estimate from Carretta et al. (2017); abundance estimate was multiplied
by 0.35, as 35 percent of the population is estimated to be in the water at any given time (Huber et al. 2001;
U.S. Navy 2014). Area representing range of the stock is 31,000 km\2\ (U.S. Navy 2014).
\7\ Estimated density based on abundance estimate from Carretta et al. (2017), with adult males assumed to be at
rookeries subtracted from abundance estimate (U.S. Navy, 2014). Area representing range of the stock is
2,032,000 km\2\ (U.S. Navy 2014).
Species with Take Estimates Less than Mean Group Size: Using the
approach described above to estimate take, the take estimates for the
sei whale, sperm whale, killer whale, short-finned pilot whale, false
killer whale, bottlenose dolphin, short beaked common dolphin, striped
dolphin, Pacific white sided dolphin, Risso's dolphin and Northern
right whale dolphin were less than the average group sizes estimated
for these species (Table 8). However, information on the social
structures and life histories of these species indicates it is common
for these species to be encountered in groups. The results of take
calculations support the likelihood that SIO's survey is expected to
encounter and to incidentally take these species, and we believe it is
likely that these species may be encountered in groups, therefore it is
reasonable to conservatively assume that one group of each of these
species will be taken during the planned survey. We therefore authorize
the take of the average (mean) group size for these species and stocks
to account for the possibility that SIO's survey encounters a group of
any of these species or stocks (Table 8).
No density data were available for the false killer whale or the
bottlenose dolphin in the planned survey area, as these species are not
typically observed in the planned survey area (Carretta et al., 2017).
However, we believe it is possible that these species may be
encountered by SIO during the planned survey. Though false killer
whales are a tropical species that is usually found in waters warmer
than those typical of the planned survey area, they have been observed
off the U.S. west coast during warm-water periods. Several sightings
were made off California during 2014-2016, when waters were unusually
warm, and historically there are very rare records farther north (pers.
comm. K. Forney, NMFS Southwest Fisheries Science Center, to J.
Carduner, NMFS, July 27, 2017). Bottlenose dolphins have not been
observed off the coast of Oregon and Washington (Carretta et al.,
2017). However, they occur frequently off the coast of California, and
they may range into Oregon and Washington waters during warm-water
periods. (Carretta et al., 2017). Though no density data are available,
we believe it is reasonable to conservatively assume that SIO's planned
survey may encounter and incidentally take false killer whales and
bottlenose dolphins. We therefore authorize the take of the average
(mean) group size for both species (Table 8).
It should be noted that the take numbers shown in Table 8 are
believed 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 (equivalent to adding 25 percent to the
planned line km to be surveyed) 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. Additionally, marine mammals would be expected to move away
from a loud sound source that represents an aversive stimulus,
potentially reducing the number of Level A takes. 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 take
estimates shown in Table 8.
For some marine mammal species, we authorize a different number of
incidental takes than the number of incidental takes requested by SIO
(see Table 7 in the IHA application for requested take numbers). For
instance, for several species, SIO increased the take request from the
calculated take number to 1 percent of the estimated population size.
However, we do not believe it is likely that 1 percent of the estimated
population size of those species will be taken by SIO's planned survey,
therefore we authorize take numbers as shows in Table 8, which we
believe are based on the best available information.
To calculate distances to isopleths corresponding to Level A
harassment thresholds using Peak SPLflat, LDEO first ran the
modeling for a single shot and then applied a high pass filter for each
hearing group based on the group's generalized hearing range. A high
pass filter is a type of band-pass filter, which pass frequencies
within a defined range without reducing amplitude and attenuate
frequencies outside that defined range (Yost 2007). LDEO ran the
modeling both with and without the application of the high pass filter
and SIO included information on isopleths corresponding to Level A
harassment thresholds both with and without the high pass filter in
their IHA application. The Technical Guidance referred to auditory
weighting functions based on a generic band-pass filter (NMFS 2016).
However, it is important to note that the two datasets relied upon to
define peak SPL thresholds, either directly or as a surrogate means to
derive thresholds for groups where no data are available (i.e., a
beluga exposed to seismic water gun and harbor porpoise exposed to a
single airgun) did not use a filter of any kind (i.e., thresholds
provided were flat across the entire spectrum of the sound source).
Therefore, for the purposes of modeling isopleths corresponding to
Level A harassment thresholds using Peak SPLflat, NMFS
believes that sound produced from the Revelle airgun array should be
considered flat to result in no weighting/high pass filtering of any
type at this time. Therefore, for the purposes of the take calculation,
we rely on the distances to isopleths corresponding to Level A
harassment thresholds using Peak SPLflat based on modeling
performed by LDEO without the high pass filter applied. Thus, the Level
A take numbers shown in Table 8 for harbor porpoise, Dall's porpoise
and harbor seal are higher than the Level A take numbers requested by
SIO as they are the result of modeling of isopleths corresponding to
Level A harassment thresholds using Peak SPLflat with no
weighting/high pass filtering applied. Level A take numbers for other
species are not affected.
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
[[Page 49326]]
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.
SIO 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 mitigation measures into their
project description based on the above sources.
To reduce the potential for disturbance from acoustic stimuli
associated with the activities, SIO will implement the following
mitigation measures for marine mammals:
(1) Vessel-based visual mitigation monitoring;
(2) Establishment of an exclusion zone and buffer zone;
(3) Shutdown procedures;
(4) Ramp-up procedures; and
(5) Ship strike avoidance measures.
In addition to these measures, NMFS proposed the following
additional mitigation measures:
(1) Shutdown for a killer whale observed at any distance; and
(2) Shutdown for a north Pacific right whale observed at any
distance.
Vessel-Based Visual Mitigation Monitoring
Protected Species Observer (PSO) observations will take place
during all daytime airgun operations and nighttime start ups (if
applicable) of the airguns. If airguns are operating throughout the
night, observations will begin 30 minutes prior to sunrise. If airguns
are operating after sunset, observations will continue until 30 minutes
following sunset. Following a shutdown for any reason, observations
will occur for at least 30 minutes prior to the planned start of airgun
operations. Observations will also occur for 30 minutes after airgun
operations cease for any reason. Observations will also be made during
daytime periods when the Revelle is underway without seismic
operations, such as during transits, to allow for comparison of
sighting rates and behavior with and without airgun operations and
between acquisition periods. Airgun operations will be suspended when
marine mammals are observed within, or about to enter, the designated
Exclusion Zone (EZ) (as described below).
During seismic operations, at least three visual PSOs will be based
aboard the Revelle. PSOs will be appointed by SIO with NMFS approval.
During the majority of seismic operations, two PSOs will monitor for
marine mammals around the seismic vessel. A minimum of one PSO must be
on duty at all times when the array is active. PSO(s) will be on duty
in shifts of duration no longer than 4 hours. Other crew will also be
instructed to assist in detecting marine mammals and in implementing
mitigation requirements (if practical). Before the start of the seismic
survey, the crew will be given additional instruction in detecting
marine mammals and implementing mitigation requirements.
The Revelle is a suitable platform from which PSOs will watch for
marine mammals. The Revelle has been used for that purpose during the
routine California Cooperative Oceanic Fisheries Investigations
surveys. Observing stations are located at the 02 level, with the
observer eye level at ~10.4 m above the waterline. At a forward-
centered position on the 02 deck, the view is ~240[deg] an aft-centered
view includes the 100-m radius area around the GI airguns. The observer
eye level on the bridge is ~15 m above sea level. Standard equipment
for marine mammal observers will be 7 x 50 reticule binoculars and
optical range finders. At night, night-vision equipment will be
available. The observers will be in communication with ship's officers
on the bridge and scientists in the vessel's operations laboratory, so
they can advise promptly of the need for avoidance maneuvers or seismic
source shutdown.
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 have been be provided to NMFS for
approval. At least one PSO must have a minimum of 90 days at-sea
experience working as PSOs during a seismic survey. One ``experienced''
visual PSO will be designated as the lead for the entire protected
species observation team. The lead will serve as primary point of
contact for the vessel operator.
The PSOs must have successfully completed relevant training,
including completion of all required coursework and passing a written
and/or oral examination developed for the training program, and must
have successfully attained a bachelor's degree from an accredited
college or university with a major in one of the natural sciences and a
minimum of 30 semester hours or equivalent in the biological sciences
and at least one undergraduate course in math or statistics. The
educational requirements may be waived if the PSO has acquired the
relevant skills through alternate training, including (1) secondary
education and/or experience comparable to PSO duties; (2) previous work
experience conducting academic, commercial, or government-sponsored
marine mammal surveys; or (3) previous work experience as a PSO; the
PSO should demonstrate good standing and consistently good performance
of PSO duties.
Exclusion Zone and Buffer Zone
An EZ is a defined area within which occurrence of a marine mammal
triggers mitigation action intended to reduce the potential for certain
outcomes, e.g., auditory injury, disruption of critical behaviors. The
PSOs will establish a minimum EZ with a 100 m radius for the airgun
array. The 100 m EZ will be based on radial distance from any
[[Page 49327]]
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, enters, or
appears on a course to enter this zone, the acoustic source will be
shut down (see Shut Down Procedures below).
The 100 m radial distance of the standard EZ is precautionary in
the sense that it would be expected to contain sound exceeding peak
pressure injury criteria for all marine mammal hearing groups (Table 6)
while also providing a consistent, reasonably observable zone within
which PSOs would typically be able to conduct effective observational
effort. In this case, the 100 m radial distance would also be expected
to contain sound that would exceed the Level A harassment threshold
based on sound exposure level (SELcum) criteria for all
marine mammal hearing groups (Table 6). In the 2011 Programmatic
Environmental Impact Statement for marine scientific research funded by
NSF or the U.S. Geological Survey (NSF-USGS 2011), Alternative B (the
Preferred Alternative) conservatively applied a 100 m EZ for all low-
energy acoustic sources in water depths >100 m, with low-energy
acoustic sources defined as any towed acoustic source with a single or
a pair of clustered airguns with individual volumes of <=250 in\3\.
Thus the 100 m EZ for this survey is consistent with the PEIS.
Our intent in prescribing a standard exclusion zone distance is to
(1) encompass zones within which auditory injury could occur on the
basis of instantaneous exposure; (2) provide additional protection from
the potential for more severe behavioral reactions (e.g., panic,
antipredator response) for marine mammals at relatively close range to
the acoustic source; (3) provide consistency for PSOs, who need to
monitor and implement the EZ; and (4) define a distance within which
detection probabilities are reasonably high for most species under
typical conditions.
PSOs will also establish and monitor a 200 m buffer zone. During
use of the acoustic source, occurrence of marine mammals within the
buffer zone (but outside the exclusion zone) will be communicated to
the operator to prepare for potential shutdown of the acoustic source.
The buffer zone is discussed further under Ramp Up Procedures below.
PSOs will also monitor the entire extent of the Level B zone, or as far
as possible if the extent of the Level B zone is not visible.
Shutdown Procedures
If a marine mammal is detected outside the EZ but is likely to
enter the EZ, and if the vessel's speed and/or course cannot be changed
to avoid having the animal enter the EZ, the airguns will be shut down
before the animal is within the EZ. Likewise, if a marine mammal is
already within the EZ when first detected, the airguns will be shut
down immediately.
Following a shutdown, airgun activity will not resume until the
marine mammal has cleared the 100 m EZ. The animal will be considered
to have cleared the 100 m EZ if the following conditions have been met:
It is visually observed to have departed the 100 m EZ, or
it has not been seen within the 100 m EZ for 15 minutes in
the case of small odontocetes, or
it has not been seen within the 100 m EZ for 30 minutes in
the case of mysticetes and large odontocetes, including sperm, pygmy
sperm, dwarf sperm, and beaked whales.
This shutdown requirement will be in place for all marine mammals,
with the exception of small delphinoids under certain circumstances. 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 will apply solely to specific genera of small dolphins--
Tursiops, Stenella, Delphinus, Lagenorhynchus and Lissodelphis--and
will only apply if the animals were traveling, including approaching
the vessel. If, for example, an animal or group of animals is
stationary for some reason (e.g., feeding) and the source vessel
approaches the animals, the shutdown requirement applies. An animal
with sufficient incentive to remain in an area rather than avoid an
otherwise aversive stimulus could either incur auditory injury or
disruption of important behavior. If there is uncertainty regarding
identification (i.e., whether the observed animal(s) belongs to the
group described above) or whether the animals are traveling, the
shutdown will be implemented.
We include this small delphinoid exception because shutdown
requirements for small delphinoids under all circumstances represent
practicability concerns without likely commensurate benefits for the
animals in question. Small delphinoids are generally the most commonly
observed marine mammals in the specific geographic region and would
typically be the only marine mammals likely to intentionally approach
the vessel. As described below, 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). Please see ``Potential Effects of the Specified Activity on
Marine Mammals'' above for further discussion of sound metrics and
thresholds and marine mammal hearing.
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
Revelle 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 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
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.
At any distance, shutdown of the acoustic source will also be
required upon observation of any of the following:
A killer whale;
a large whale (i.e., sperm whale or any baleen whale) with
a calf;
a north Pacific right whale; or
an aggregation of large whales of any species (i.e., sperm
whale or any baleen whale) that does not appear to be traveling (e.g.,
feeding, socializing, etc.).
These are the only potential situations that would require shutdown
of the array for marine mammals observed beyond the 100 m EZ. Killer
whales belonging to the Southern Resident
[[Page 49328]]
distinct population segment (DPS) are not expected to occur in the area
of the planned survey as the easternmost track lines of the planned
survey (those that approach nearest to shore) are further west than the
migratory range of the Southern Resident stock off Oregon and southern
Washington (pers. comm., B. Hanson, NMFS Northwest Fishery Science
Center to J. Carduner, NMFS Office of Protected Resources (OPR), April
12, 2017). As the Eastern North Pacific Southern Resident stock would
be expected to occur closer to shore than the planned survey area, the
survey is not expected to encounter any individuals from this stock.
However, as the known migratory range of the Southern Resident DPS
occurs near the planned survey area, and due to the precarious
conservation status of the Southern Resident killer whale DPS, NMFS
believes it is reasonable to implement measures that are conservative
and also practicable in order to prevent the potential for a Southern
Resident killer whale to be exposed to airgun sounds. Thus the
requirement to shut down the array upon observation of a killer whale
at any distance is designed to avoid any potential for harassment of
any Southern Resident killer whales.
As described above, we do not expect the survey to encounter a
north Pacific right whale and take of north Pacific right whales is not
authorized. However, in the extremely rare event that a north Pacific
right whale was observed at any distance, the array would be shut down
and would not be activated until 30 minutes had elapsed since the most
recent sighting.
Ramp-Up Procedures
Ramp-up of an acoustic source is intended to provide a gradual
increase in sound levels following a shutdown, enabling animals to move
away from the source if the signal is sufficiently aversive prior to
its reaching full intensity. Ramp-up will be required after the array
is shut down for any reason. Ramp-up will begin with the activation of
one 45 in\3\ airgun, with the second 45 in\3\ airgun activated after 5
minutes.
PSOs are required to monitor during ramp-up. During ramp up, the
PSOs will monitor the EZ, and if marine mammals were observed within or
approaching the 100 m EZ, a shutdown will be implemented as though the
full array were operational. If airguns have been shut down due to PSO
detection of a marine mammal within or approaching the 100 m EZ, ramp-
up will not be initiated until all marine mammals have cleared the EZ,
during the day or night. Criteria for clearing the EZ will be as
described above.
Thirty minutes of pre-clearance observation are required prior to
ramp-up for any shutdown of longer than 30 minutes (i.e., if the array
were shut down during transit from one line to another). This 30 minute
pre-clearance period may occur during any vessel activity (i.e.,
transit). If a marine mammal were observed within or approaching the
100 m EZ during this pre-clearance period, ramp-up will not be
initiated until all marine mammals cleared the EZ. Criteria for
clearing the EZ will be as described above. If the airgun array has
been shut down for reasons other than mitigation (e.g., mechanical
difficulty) for a period of less than 30 minutes, it may be activated
again without ramp-up if PSOs have maintained constant visual
observation and no detections of any marine mammal have occurred within
the EZ or buffer zone. Ramp-up will be planned to occur during periods
of good visibility when possible. However, ramp-up is allowed at night
and during poor visibility if the 100 m EZ and 200 m buffer zone have
been monitored by visual PSOs for 30 minutes prior to ramp-up.
The operator will be required to 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. A designated PSO must be notified again immediately
prior to initiating ramp-up procedures and the operator must receive
confirmation from the PSO to proceed. The operator must provide
information to PSOs documenting that appropriate procedures were
followed. Following deactivation of the array for reasons other than
mitigation, the operator is required to communicate the near-term
operational plan to the lead PSO with justification for any planned
nighttime ramp-up.
Speed or Course Alteration
If a marine mammal is detected outside the EZ, based on its
position and the relative motion, is likely to enter the EZ, the
vessel's speed and/or direct course could be changed. This will be done
if operationally practicable while minimizing the effect on the planned
science objectives. The activities and movements of the marine mammal
(relative to the seismic vessel) will then be closely monitored to
determine whether the animal is approaching the EZ. If the animal
appears likely to enter the EZ, a shutdown of the seismic source will
cocur. Typically, during seismic operations, the source vessel is
unable to change speed or course and one or more alternative mitigation
measures (as described above) will need to be implemented.
Based on our evaluation of the mitigation measures as described
above, 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 of the species and of the level of taking or impacts on
populations of marine mammals that are expected to be present in the
planned 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;
[[Page 49329]]
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.
SIO submitted a marine mammal monitoring and reporting plan in
section XIII of their IHA application. Monitoring that is designed
specifically to facilitate mitigation measures, such as monitoring of
the EZ to inform potential shutdowns of the airgun array, are described
above and are not repeated here.
SIO's monitoring and reporting plan includes the following
measures:
Vessel-Based Visual Monitoring
As described above, PSO observations will take place during daytime
airgun operations and nighttime start ups (if applicable) of the
airguns. During seismic operations, three visual PSOs will be based
aboard the Revelle. PSOs will be appointed by SIO with NMFS approval.
During the majority of seismic operations, one PSO will monitor for
marine mammals around the seismic vessel. PSOs will be on duty in
shifts of duration no longer than 4 hours. Other crew will also be
instructed to assist in detecting marine mammals and in implementing
mitigation requirements (if practical). During daytime, PSOs will scan
the area around the vessel systematically with reticle binoculars
(e.g., 7x50 Fujinon), Big-eye binoculars (25x150), and with the naked
eye.
PSOs will record data to estimate the numbers of marine mammals
exposed to various received sound levels and to document apparent
disturbance reactions or lack thereof. Data will be used to estimate
numbers of animals potentially `taken' by harassment (as defined in the
MMPA). They will also provide information needed to order a shutdown of
the airguns when a marine mammal is within or near the EZ. When a
sighting is made, the following information about the sighting will be
recorded:
1. Species, group size, age/size/sex categories (if determinable),
behavior when first sighted and after initial sighting, heading (if
consistent), bearing and distance from seismic vessel, sighting cue,
apparent reaction to the airguns or vessel (e.g., none, avoidance,
approach, paralleling, etc.), and behavioral pace.
2. Time, location, heading, speed, activity of the vessel, sea
state, visibility, and sun glare.
All observations and shutdowns will be recorded in a standardized
format. Data will be entered into an electronic database. The accuracy
of the data entry will be verified by computerized data validity checks
as the data are entered and by subsequent manual checking of the
database. These procedures will allow initial summaries of data to be
prepared during and shortly after the field program and will facilitate
transfer of the data to statistical, graphical, and other programs for
further processing and archiving. The time, location, heading, speed,
activity of the vessel, sea state, visibility, and sun glare will also
be recorded at the start and end of each observation watch, and during
a watch whenever there is a change in one or more of the variables.
Results from the vessel-based observations will provide:
1. The basis for real-time mitigation (airgun shutdown);
2. Information needed to estimate the number of marine mammals
potentially taken by harassment, which must be reported to NMFS;
3. Data on the occurrence, distribution, and activities of marine
mammals in the area where the seismic study is conducted;
4. Information to compare the distance and distribution of marine
mammals relative to the source vessel at times with and without seismic
activity; and
5. Data on the behavior and movement patterns of marine mammals
seen at times with and without seismic activity.
Reporting
A report will be submitted to NMFS within 90 days after the end of
the cruise. The report will describe the operations that were conducted
and sightings of marine mammals near the operations. The report will
provide full documentation of methods, results, and interpretation
pertaining to all monitoring. The 90-day report will summarize the
dates and locations of seismic operations, and all marine mammal
sightings (dates, times, locations, activities, associated seismic
survey activities). The report will also include estimates of the
number and nature of exposures that occurred above the harassment
threshold based on PSO observations, including an estimate of those on
the trackline but not detected.
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' 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 the species listed
in Table 1, given that NMFS expects the anticipated effects of the
planned seismic survey to be similar in nature. Where there are
meaningful differences between species or stocks, or groups of species,
in anticipated individual responses to activities, impact of expected
take on the population due to differences in population status, or
impacts on habitat, NMFS has identified species-specific factors to
inform the analysis.
NMFS does not anticipate that serious injury or mortality will
occur as a result of SIO's planned seismic 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 authorize a limited number of instances of Level A harassment
(Table 8) for four species. However, we believe that any PTS incurred
in marine mammals as a result of the planned activity will 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 Revelle and of the marine mammals in the
project area, as well as the fact that the vessel is not expected to
remain in
[[Page 49330]]
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 are 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
Revelle's approach due to the vessel's relatively low speed when
conducting seismic surveys. We expect that the majority of takes will
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 will be
temporary. Feeding behavior is not likely to be significantly impacted,
as marine mammals appear to be less likely to exhibit behavioral
reactions or avoidance responses while engaged in feeding activities
(Richardson et al., 1995). Prey species are mobile and are broadly
distributed throughout the project area; 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 temporary nature
of the disturbance, the availability of similar habitat and resources
in the surrounding area, and the lack of important or unique marine
mammal habitat, 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. In
addition, there are no mating or calving areas known to be biologically
important to marine mammals within the planned project area.
The activity is expected to impact a very small percentage of all
marine mammal stocks affected by SIO's planned survey (less than 7
percent each for all marine mammal stocks). Additionally, the acoustic
``footprint'' of the planned survey will be very small relative to the
ranges of all affected marine mammals . Sound levels will increase in
the marine environment in a relatively small area surrounding the
vessel compared to the range of the marine mammals within the planned
survey area. The seismic array will be active 24 hours per day
throughout the duration of the planned survey. However, the very brief
overall duration of the planned survey (five days) will further limit
potential impacts that may occur as a result of the planned activity.
As noted above, take estimates for four species have been revised since
we published the proposed IHA. Our analysis reflects these revised
numbers (Table 8).
The mitigation measures are expected to reduce the number and/or
severity of takes by allowing for detection of marine mammals in the
vicinity of the vessel by visual and acoustic observers, and by
minimizing the severity of any potential exposures via shutdowns of the
airgun array. Based on previous monitoring reports for substantially
similar activities that have been previously authorized by NMFS, we
expect that the mitigation measures will be effective in preventing at
least some extent of potential PTS in marine mammals that may otherwise
occur in the absence of the mitigation measures.
Of the marine mammal species under our jurisdiction that are likely
to occur in the project area, the following species are listed as
endangered under the ESA: Humpback, blue, fin, sei, and sperm whales.
Population estimates for humpback whales for the North Pacific have
increased substantially from 1,200 in 1966 to approximately 18,000-
20,000 whales in 2004 to 2006 (Calambokidis et al. 2008) indicating a
growth rate of 6-7 percent (Carretta et al., 2017). There are currently
insufficient data to determine population trends for blue, fin, sei,
and sperm whales (Carretta et al., 2017); however, we are proposing to
authorize very small numbers of takes for these species (Table 8),
relative to their population sizes, therefore we do not expect
population-level impacts to any of these species. The other marine
mammal species that may be taken by harassment during SIO's seismic
survey are not listed as threatened or endangered under the ESA. There
is no designated critical habitat for any ESA-listed marine mammals
within the project area; and of the non-listed marine mammals for which
we authorize take, none are considered ``depleted'' or ``strategic'' by
NMFS under the MMPA.
NMFS concludes that exposures to marine mammal species and stocks
due to SIO's planned seismic survey will result in only short-term
(temporary and short in duration) effects to individuals exposed, or
some small degree of PTS to a very small number of individuals of four
species. 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 take estimates 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 marine mammal species or
stocks through effects on annual rates of recruitment or survival:
No mortality is anticipated or authorized;
The anticipated impacts of the planned activity on marine
mammals will primarily be temporary behavioral changes due to avoidance
of the area around the survey vessel. The relatively short duration of
the planned survey (5 days) will further limit the potential impacts of
any temporary behavioral changes that may occur;
The number of instances of PTS that may occur are expected
to be very small in number (Table 8). 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 planned survey area does not contain areas of
significance for feeding, mating or calving;
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;
The mitigation measures, including visual and acoustic
monitoring 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 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.
[[Page 49331]]
Small Numbers
As noted above, only small numbers of incidental take may be
authorized under Section 101(a)(5)(D) of the MMPA for specified
activities other than military readiness activities. The MMPA does not
define small numbers; 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 8 provides numbers of take by Level A harassment
and Level B harassment authorized. These are the numbers we use for
purposes of the small numbers analysis.
The numbers of marine mammals that we authorize to be taken, for
all species and stocks, would be considered small relative to the
relevant stocks or populations (less than 7 percent for all species and
stocks). Based on the analysis contained herein of the planned activity
(including the mitigation and monitoring measures) and the anticipated
take of marine mammals, NMFS finds that small numbers of marine mammals
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 will not
have an unmitigable adverse impact on the availability of such species
or stocks for taking for subsistence purposes.
Endangered Species Act (ESA)
Section 7(a)(2) of the Endangered Species Act of 1973 (16 U.S.C.
1531 et seq.) requires that each Federal agency insure that any action
it authorizes, funds, or carries out is not likely to jeopardize the
continued existence of any endangered or threatened species or result
in the destruction or adverse modification of designated critical
habitat. To ensure ESA compliance for the issuance of IHAs, NMFS
consults internally, in this case with the ESA Interagency Cooperation
Division, whenever we propose to authorize take for endangered or
threatened species.
The NMFS Permits and Conservation Division are authorizing the
incidental take of 5 species of marine mammals which are listed under
the ESA: The humpback whale (Mexico DPS), sei whale, fin whale, blue
whale and sperm whale. Under Section 7 of the ESA, we initiated
consultation with the NMFS OPR Interagency Cooperation Division for the
issuance of this IHA. In September, 2017, the NMFS OPR Interagency
Cooperation Division issued a Biological Opinion with an incidental
take statement, which concluded that the issuance of the IHA was not
likely to jeopardize the continued existence of the humpback whale
(Mexico DPS), sei whale, fin whale, blue whale and sperm whale. The
Biological Opinion also concluded that the issuance of the IHA would
not destroy or adversely modify designated critical habitat for these
species.
Authorization
NMFS has issued an IHA to the SIO for the potential harassment of
small numbers of 27 marine mammal species incidental to a low-energy
marine geophysical survey in the northeast Pacific Ocean, provided the
previously mentioned mitigation, monitoring and reporting requirements
are incorporated.
Dated: October 19, 2017.
Donna S. Wieting,
Director, Office of Protected Resources, National Marine Fisheries
Service.
[FR Doc. 2017-23132 Filed 10-24-17; 8:45 am]
BILLING CODE 3510-22-P