[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
----------------------------------------------------------------------------------------------------------------
                                                                    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)
----------------------------------------------------------------------------------------------------------------
                                             Family: Balaenopteridae
----------------------------------------------------------------------------------------------------------------
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).
----------------------------------------------------------------------------------------------------------------
        Order Cetartiodactyla--Cetacea--Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
----------------------------------------------------------------------------------------------------------------
                                              Family: Physeteridae
----------------------------------------------------------------------------------------------------------------
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)
----------------------------------------------------------------------------------------------------------------
                                                Family: Kogiidae
----------------------------------------------------------------------------------------------------------------
Pygmy sperm whale (Kogia        California/       -/-; N           4,111 (1.12;             19  Rare.
 breviceps).                     Oregon/                            1,924; 2014).
                                 Washington.
----------------------------------------------------------------------------------------------------------------

[[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)
----------------------------------------------------------------------------------------------------------------
                                               Family: delphinidae
----------------------------------------------------------------------------------------------------------------
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.
----------------------------------------------------------------------------------------------------------------
        Order Cetartiodactyla--Cetacea--Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
----------------------------------------------------------------------------------------------------------------
                                                Family: Ziphiidae
----------------------------------------------------------------------------------------------------------------
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.
----------------------------------------------------------------------------------------------------------------
                                     Order Carnivora--Superfamily Pinnipedia
----------------------------------------------------------------------------------------------------------------
                                  Family: Otariidae (eared seals and sea lions)
----------------------------------------------------------------------------------------------------------------
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.
----------------------------------------------------------------------------------------------------------------
                                        Family: Phocidae (earless seals)
----------------------------------------------------------------------------------------------------------------
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.
----------------------------------------------------------------------------------------------------------------
\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):
    <bullet> 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;
    <bullet> 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;
    <bullet> 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.
    <bullet> 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;
    <bullet> 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 
(SEL<INF>cum</INF>) 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 SEL<INF>cum</INF> metric 
considers both level and duration of exposure, as well as auditory 
weighting functions by marine mammal hearing group. In recognition of 
the fact that the requirement to calculate Level A harassment 
ensonified areas could be more technically challenging to predict due 
to the duration component and the use of weighting functions in the new 
SEL<INF>cum</INF> thresholds, NMFS developed an optional User 
Spreadsheet that includes tools to help predict a simple isopleth that 
can be used in conjunction with marine mammal density or occurrence to 
facilitate the estimation of take numbers.
    The values for SEL<INF>cum</INF> and peak SPL for the 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 SEL<INF>cum</INF> 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 (SEL<INF>cum</INF> or Peak SPL<INF>flat</INF>) 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 SPL<INF>flat</INF>, 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 SPL<INF>flat</INF>, 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 SPL<INF>flat</INF> 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 SPL<INF>flat</INF> 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 (SEL<INF>cum</INF>) 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:
    <bullet> It is visually observed to have departed the 100 m EZ, or
    <bullet> it has not been seen within the 100 m EZ for 15 minutes in 
the case of small odontocetes, or
    <bullet> 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:
    <bullet> A killer whale;
    <bullet> a large whale (i.e., sperm whale or any baleen whale) with 
a calf;
    <bullet> a north Pacific right whale; or
    <bullet> 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:
    <bullet> Occurrence of marine mammal species or stocks in the area 
in which take is anticipated (e.g., presence, abundance, distribution, 
density);
    <bullet> Nature, scope, or context of likely marine mammal exposure 
to potential stressors/impacts (individual or cumulative, acute or 
chronic), through better understanding of: (1) Action or environment 
(e.g., source characterization, propagation, ambient noise); (2) 
affected species (e.g., life history, dive patterns); (3) co-occurrence 
of marine mammal species with the action; or (4) biological or 
behavioral context of exposure (e.g., age, calving or feeding areas);
    <bullet> Individual marine mammal responses (behavioral or 
physiological) to acoustic stressors (acute, chronic, or cumulative), 
other stressors, or cumulative impacts from multiple stressors;
    <bullet> How anticipated responses to stressors impact either: (1) 
Long-term fitness and survival of individual marine mammals; or (2) 
populations, species, or stocks;

[[Page 49329]]

    <bullet> Effects on marine mammal habitat (e.g., marine mammal prey 
species, acoustic habitat, or other important physical components of 
marine mammal habitat); and
    <bullet> Mitigation and monitoring effectiveness.
    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:
    <bullet> No mortality is anticipated or authorized;
    <bullet> 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;
    <bullet> 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);
    <bullet> 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;
    <bullet> The planned survey area does not contain areas of 
significance for feeding, mating or calving;
    <bullet> 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;
    <bullet> 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