[Federal Register Volume 83, Number 116 (Friday, June 15, 2018)]
[Notices]
[Pages 27954-27972]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2018-12907]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

RIN 0648-XF986


Takes of Marine Mammals Incidental to Specified Activities; 
Taking Marine Mammals Incidental to a Low-Energy Geophysical Survey in 
the Northwest Atlantic 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 take marine mammals 
incidental to a low-energy marine geophysical survey in the Northwest 
Atlantic Ocean.

DATES: This authorization is valid for one year from the date of 
issuance.

FOR FURTHER INFORMATION CONTACT: Jordan Carduner, Office of Protected 
Resources, NMFS, (301) 427-8401. Electronic copies of the application 
and supporting documents, as well as a list of the references cited in 
this document, may be obtained online at: www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-research-and-other-activities. In case of problems accessing these 
documents, please call the contact listed above.

SUPPLEMENTARY INFORMATION:

Background

    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. This action is consistent with categories of 
activities identified in Categorical Exclusion B4 (incidental 
harassment authorizations with no anticipated serious injury or 
mortality) of the Companion Manual for NOAA Administrative Order 216-
6A, which do not individually or cumulatively have the potential for 
significant impacts on the quality of the human environment and for 
which we have not identified any extraordinary circumstances that would 
preclude this categorical exclusion. Accordingly, NMFS has determined 
that the issuance of the IHA qualifies to be categorically excluded 
from further NEPA review.

Summary of Request

    On November 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 Northwest Atlantic Ocean. On February 8, 
2018, we deemed SIO's application for authorization to be adequate and 
complete. SIO's request is for take of a

[[Page 27955]]

small number of 35 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

Overview

    SIO plans to conduct a low-energy marine seismic survey in the 
Northwest Atlantic Ocean for approximately 25 days during June-July 
2018. The survey would occur in International Waters, between 
~33.5[deg] and 53.5[deg] N, and 37[deg] and 49[deg] W, at water depths 
ranging from 1,800 to over 5,000 meters (m) (see Figure 1 in the IHA 
application) and would entail one source vessel, the R/V Atlantis, 
which would tow a pair of 45 cubic inch (in\3\) GI airguns at a depth 
of 2-4 m with a total discharge volume of approximately 90 in\3\ as an 
energy source along predetermined lines. The receiving system would 
consist of one hydrophone streamer, either 200 or 600 m in length. The 
program consists of a site survey in support of a potential future 
International Ocean Discovery Program project and would examine 
regional seismic stratigraphy and provide seismic images of changing 
sediment distributions from deepwater production changes. The Principal 
Investigators are Drs. M. Lyle (Oregon State University), G. Mountain 
(Rutgers University), and K. Miller (Rutgers University).
    The survey would use two different types of airgun array 
configurations. The first would entail a pair of 45-in\3\ airguns 
spaced 8 m apart at a water depth of 2-4 m with a 200 m hydrophone 
streamer and with the vessel traveling at 8 knots (kt). The second 
would entail a pair of 45-in\3\ airguns, but with airguns spaced 2 m 
apart at a depth of 2-4 m with a 600 m hydrophone streamer and with the 
vessel traveling at 5 kt to achieve especially high-quality seismic 
reflection data. Data would be collected within six grids, and also 
along track lines between the six grid locations (see Figure 1 in the 
IHA application). A total of 7,911 kilometers (km) of seismic 
acquisition would occur, including 4,334 km of data collected within 
the survey grids (2667 km at 8 kt and 1667 km at 5 kt) and an 
additional 3,577 km of track lines connecting the grids. There could be 
additional seismic operations in the project area associated with 
equipment testing, re-acquisition due to equipment malfunction, data 
degradation during poor weather, or interruption due to shutdown or 
track deviation in compliance with IHA requirements.
    In addition to the operations of the airgun array, a multibeam 
echosounder (MBES) and a sub-bottom profiler (SBP) would also be 
operated continuously throughout the survey, but not during transits to 
and from the project area. The MBES (a Kongsberg EM122) operates at 
10.5-13 (usually 12) kilohertz (kHz) and is hull-mounted, with the 
transmitting beamwidth 1 or 2[deg] fore-aft and 150[deg] athwartship. 
The SBP (a Knudsen 3260) is normally operated to provide information 
about the near seafloor sedimentary features and the bottom topography 
that is mapped simultaneously by the MBES. The beam of the SBP is 
transmitted as a 27[deg] cone, which is directed downward by a 3.5-kHz 
transducer in the hull of the vessel.

        Table 1--Specifications of the R/V Atlantis Airgun Array
------------------------------------------------------------------------
 
------------------------------------------------------------------------
Number of airguns......................  2.
Gun positions used.....................  Two inline airguns 2- or 8-m
                                          apart.
Tow depth of energy source.............  2-4 m.
Dominant frequency components..........  0-188 Hz.
Air discharge volume...................  Approximately 90 in\3\.
Shot interval..........................  9.72 seconds (2 m airgun
                                          separation survey) and 12.15
                                          seconds (8 m airgun separation
                                          survey).
------------------------------------------------------------------------

    A detailed description of SIO's planned survey is provided in the 
Federal Register notice for the proposed IHA (83 FR 18644; April 27, 
2018). Since that time, no changes have been made to SIO's planned 
survey activities. Therefore, a detailed description is not provided 
here. Please refer to that Federal Register notice for the description 
of the specific activity. Mitigation, monitoring, and reporting 
measures are described in detail later in this document (please see 
``Mitigation'' and ``Monitoring and Reporting'').

Comments and Responses

    NMFS published a notice of proposed IHA in the Federal Register on 
April 27, 2018 (83 FR 18644). During the 30-day public comment period, 
NMFS received a comment letter from the Marine Mammal Commission 
(Commission). NMFS has posted the comments online at: 
www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-research-and-other-activities. 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: 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, and that the model provides results to a water 
depth of 2,000 m while SIO's planned survey would occur in waters from 
1,800 to more than 5,000 m in depth. In light of their concerns, the 
Commission recommended that NMFS require SIO, in collaboration with 
Lamont-Doherty Earth Observatory of Columbia University (LDEO) (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 (1) operational (including number/type/spacing 
of airguns, tow depth, source level/operating pressure, operational 
volume) and site-specific environmental (including sound speed 
profiles, bathymetry, and sediment characteristics at a minimum) 
parameters; (2) a comprehensive source model (i.e., Gundalf Optimizer 
or AASM) and (3) an appropriate sound propagation model for the 
proposed IHA. Specifically, the Commission states that LDEO should be 
using the ray-tracing sound propagation model BELLHOP, rather than the 
MATLAB code currently used.

[[Page 27956]]

    NMFS 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, 2018) and the 
Federal Register notice of the proposed IHA (83 FR 18644; April 27, 
2018) describe the applicant's approach to modeling Level A and Level B 
harassment zones. The model LDEO currently uses does not allow for the 
consideration of environmental and site-specific parameters as 
requested by the Commission.
    SIO's application (LGL, 2018) describes their approach to modeling 
Level A and Level B harassment zones. In summary, LDEO acquired field 
measurements for several array configurations at shallow, intermediate, 
and deep-water depths during acoustic verification studies conducted in 
the northern Gulf of Mexico in 2007 and 2008 (Tolstoy et al., 2009). 
Based on the empirical data from those studies, LDEO 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, LDEO 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). LDEO 
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).
    In 2015, LDEO explored the question of whether the Gulf of Mexico 
calibration data described above adequately informs the model to 
predict exclusion isopleths in other areas by conducting a 
retrospective sound power analysis of one of the lines acquired during 
L-DEO's seismic survey offshore New Jersey in 2014 (Crone, 2015). NMFS 
presented a comparison of the predicted radii (i.e., modeled exclusion 
zones) with radii based on in situ measurements (i.e., the upper bound 
[95th percentile] of the cross-line prediction) in a previous notice of 
issued Authorization for LDEO (see 80 FR 27635, May 14, 2015, Table 1). 
Briefly, the analysis presented in Crone (2015), specific to the survey 
site offshore New Jersey, confirmed that in-situ, site specific 
measurements and estimates of 160 decibel (dB) and 180 dB isopleths 
collected by the hydrophone streamer of the R/V 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 LDEO'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 LDEO's model was 
conservative in that case.
    The following is a summary of two additional analyses of in-situ 
data that support LDEO's use of the modeled Level A and Level B 
harassment zones in this particular case. In 2010, LDEO assessed the 
accuracy of their modeling approach by comparing the sound levels of 
the field measurements acquired in the Gulf of Mexico study to their 
model predictions (Diebold et al., 2010). They reported that the 
observed sound levels from the field measurements fell almost entirely 
below the predicted mitigation radii curve for deep water (i.e., 
greater than 1,000 m; 3280.8 ft) (Diebold et al., 2010). In 2012, LDEO 
used a similar process to model distances to isopleths corresponding to 
Level A and Level B harassment thresholds for a shallow-water seismic 
survey in the northeast Pacific Ocean offshore Washington State. LDEO 
conducted the shallow-water survey using a 6,600 in\3\ airgun 
configuration aboard the R/V Marcus Langseth and recorded the received 
sound levels on both the shelf and slope using the Langseth's 8 km 
hydrophone streamer. Crone et al. (2014) analyzed those received sound 
levels from the 2012 survey and confirmed that in-situ, site specific 
measurements and estimates of the 160 dB and 180 dB isopleths collected 
by the Langseth's hydrophone streamer in shallow water were two to 
three times smaller than LDEO's modeling approach had predicted. While 
the results confirmed the role of bathymetry in sound propagation, 
Crone et al. (2014) were also able to confirm that the empirical 
measurements from the Gulf of Mexico calibration survey (the same 
measurements used to inform LDEO's modeling approach for the planned 
surveys in the northwest Atlantic Ocean) overestimated the size of the 
exclusion and buffer zones for the shallow-water 2012 survey off 
Washington State and were thus precautionary, in that particular case.
    NMFS continues to work with LDEO to address the issue of 
incorporating site-specific information for future authorizations for 
seismic surveys. However, LDEO'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 LDEO's model results and the 
field data collected at multiple locations (i.e., the Gulf of Mexico, 
offshore Washington State, and offshore New Jersey) illustrate a degree 
of conservativeness built into LDEO'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.
    LDEO 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 Level A and Level B harassment zones and for developing 
take estimates is not a requirement of the MMPA incidental take 
authorization process. Further, NMFS does not 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 2: The Commission recommended that NMFS better evaluate the 
numbers of Level A and B harassment takes it plans to propose for 
authorization by considering both ecological/biological information and 
implementation of mitigation measures for all proposed authorizations 
prior to submitting them for publication in the Federal Register. The 
Commission specifically questioned the proposed authorization of 42 
Level A takes of

[[Page 27957]]

harbor porpoises and recommended that NMFS reduce the numbers of Level 
A takes for that particular species.
    NMFS Response: We appreciate the Commission's concern with 
authorizing appropriate numbers of take and their suggestion regarding 
the specific number of Level A takes that it deems appropriate in this 
instance. We base take analyses on the best available information; in 
this case, as SIO's survey is planned in a geographic area where data 
on marine mammal abundance and density is relatively limited, the best 
available information on cetacean density (including harbor porpoise 
density) was represented by density modeling by Mannocci et al. (2017). 
We relied on this information to calculate the estimated numbers of 
takes (including Level A takes of harbor porpoise), as described in the 
proposed IHA. We also acknowledged in the proposed IHA that harbor 
porpoises would be expected to be relatively uncommon in the proposed 
survey area, and that take estimates are conservative. That said, given 
the fact that Mannocci et al. (2017) predict relatively high densities 
of harbor porpoises in offshore waters north of ~40[deg] N (where much 
of the survey would occur) and given the relative lack of information 
regarding the marine mammals that may be encountered by SIO's survey, 
we do not think a reduction in the number of Level A takes of harbor 
porpoises is necessary in this instance, given the applicant's request.
    Comment 3: the Commission questioned the necessity of the 100 m 
exclusion zone, specifically for mid-frequency (MF) cetaceans, noting 
that the Level A harassment zone is estimated to be less than 1 m for 
MF cetaceans. The Commission stated that NMFS should ensure that marine 
mammals are sufficiently protected from Level A harassment and that 
activities can be completed in an appropriate manner and within an 
appropriate timeframe, and recommended that NMFS more thoroughly assess 
the proposed exclusion zones that are to be implemented for this 
authorization and for future proposed incidental take authorizations, 
prior to publication in the Federal Register.
    NMFS Response: NMFS agrees with the Commission that mitigation 
measures should ensure sufficient protection of marine mammals while 
facilitating the timely completion of the specified activities so as to 
minimize the overall duration of those activities and their impacts on 
marine mammals. It is for this reason that NMFS has included a waiver 
to the shutdown requirement specifically for small delphinoids (which 
are expected to constitute the vast majority of MF cetaceans 
encountered by SIO's survey) that would otherwise result in a shutdown 
of SIO's survey. The shutdown requirement referenced by the Commission 
will be in place for marine mammals with the exception of small 
delphinoids (which are all in the MF functional hearing group) under 
certain circumstances. 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). The exception to the 
shutdown requirement applies solely to specific genera of small 
dolphins--Tursiops, Steno, Stenella, Lagenorhynchus and Delphinus. We 
have included this exception because shutdown requirements for small 
delphinoids under all circumstances represent practicability concerns 
without likely commensurate benefits for the animals in question, as 
referenced by the Commission. 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 referenced by the Commission, auditory injury 
is extremely unlikely to occur for MF 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. We refer 
the reader to the Federal Register notice for the proposed IHA (83 FR 
18644; April 27, 2018) 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). As referenced by 
the Commission, the potential for increased shutdowns resulting from 
such a measure would require the Atlantis to revisit the missed track 
line to reacquire data, potentially resulting in an increase in the 
total duration over which the survey is active in a given area and an 
overall increase in the total sound energy input to the marine 
environment. 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, contrary to the Commission's concerns, 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 also anticipate some 
benefit for a shutdown requirement for large delphinoids in that it 
simplifies somewhat the total range of decision-making for protected 
species observers (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. Shutdown requirements, including the 
waiver to shutdown requirements for small delphinoids, are discussed in 
greater detail in the Mitigation section below.
    Comment 4: 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, and recommended that NMFS provide 
the draft criteria for take calculation in a timely manner.
    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. We will share draft 
guidance on this issue as soon as possible with the Commission.
    Comment 5: The Commission expressed concern that information was 
missing or incorrect in the proposed IHA and SIO's application, 
including information on the proposed activities related to the 
proposed source levels, shot intervals, and source velocities and 
mitigation measures. Therefore the Commission recommended that NMFS 
review more thoroughly applications prior to deeming them complete and 
NMFS' draft notices prior to submitting them for publication in the 
Federal Register.
    NMFS Response: We appreciate the Commission pointing out the 
deficiencies in the notice of proposed IHA. In response to the 
Commission's concerns we have ensured source levels, shot intervals, 
source velocities and mitigation measures are accurately

[[Page 27958]]

described in this notice and are accurately factored into harassment 
zones and authorized take numbers. Resultant changes to harassment 
zones and take estimates are minimal and are described in the Take 
Estimate section below. NMFS thoroughly reviews all applications prior 
to deeming them complete, and thoroughly reviews draft notices prior to 
publishing in the Federal Register, and will continue to do so.
    Comment 6: The Commission requested clarification regarding certain 
issues associated with NMFS' notice that one-year renewals could be 
issued in certain limited circumstances and expressed concern that the 
process would bypass the public notice and comment requirements. The 
Commission recommended that NMFS refrain from implementing its proposed 
renewal process and instead use abbreviated Federal Register notices 
and reference existing documents to streamline the incidental 
harassment authorization process. The Commission suggested that NMFS 
should discuss the possibility of renewals through a more general 
route, such as a rulemaking, instead of notice in a specific 
authorization. The Commission further recommended that if NMFS did not 
pursue a more general route, that the agency provide the Commission and 
the public with a legal analysis supporting our conclusion that this 
process is consistent with the requirements of section 101(a)(5)(D) of 
the MMPA.
    NMFS Response: The process of issuing a renewal IHA does not bypass 
the public notice and comment requirements of the MMPA. The notice of 
the proposed IHA expressly notifies the public that under certain, 
limited conditions an applicant could seek a renewal IHA for an 
additional year. The notice describes the conditions under which such a 
renewal request could be considered and expressly seeks public comment 
in the event such a renewal is sought. Importantly, such renewals would 
be limited to circumstances where: The activities are identical or 
nearly identical to those analyzed in the proposed IHA; monitoring does 
not indicate impacts that were not previously analyzed and authorized; 
and, the mitigation and monitoring requirements remain the same, all of 
which allow the public to comment on the appropriateness and effects of 
a renewal at the same time the public provides comments on the initial 
IHA. NMFS has, however, modified the language for future proposed IHAs 
to clarify that all IHAs, including renewal IHAs, are valid for no more 
than one year and that the agency would consider only one renewal for a 
project at this time. In addition, notice of issuance or denial of a 
renewal IHA would be published in the Federal Register, as they are for 
all IHAs. The option for issuing renewal IHAs has been in NMFS's 
incidental take regulations since 1996. We will provide any additional 
information to the Commission and consider posting a description of the 
renewal process on our website before any renewal is issued utilizing 
this process.

Description of Marine Mammals in the Area of Specified Activity

    Sections 3 and 4 of SIO's IHA application summarize available 
information regarding status and trends, distribution and habitat 
preferences, and behavior and life history, of the potentially affected 
species. Additional information regarding population trends and threats 
may be found in NMFS' Stock Assessment Reports (SAR; 
www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports-region) and more general information about 
these species (e.g., physical and behavioral descriptions) may be found 
on NMFS' website (www.fisheries.noaa.gov/species-directory).
    The populations of marine mammals considered in this document do 
not occur within the U.S. exclusive economic zone (EEZ) and are 
therefore not assigned to stocks and are not assessed in NMFS' Stock 
Assessment Reports (SAR). As such, information on 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) and on annual levels of serious injury and 
mortality from anthropogenic sources are not available for these marine 
mammal populations. Abundance estimates for marine mammals in the 
survey location are lacking; therefore the abundance estimates 
presented here are based on the U.S. Atlantic SARs (Hayes et al., 2017) 
and on the Canadian Trans-North Atlantic Sighting Survey which provided 
full coverage of the Atlantic Canadian coast (Lawson and Gosselin, 
2009), as these sources are considered the best available information 
on potential abundance of marine mammals in the area. However, as 
described above, the marine mammals encountered by the proposed survey 
are not assigned to stocks. All abundance estimate values presented in 
Table 2 are the most recent available at the time of publication and 
are available in the 2017 U.S. Atlantic draft SARs (e.g., Hayes et al. 
2017) available online at: www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments, except where noted 
otherwise.
    Table 2 lists all species with expected potential for occurrence in 
the survey area and with the potential to be taken as a result of the 
proposed survey, and summarizes information related to the population, 
including regulatory status under the MMPA and ESA. For taxonomy, we 
follow Committee on Taxonomy (2016).

Table 2--Marine Mammal Species Potentially Present in the Project Area and That May be Affected by the Specified
                                                   Activities
----------------------------------------------------------------------------------------------------------------
                                                     ESA/ MMPA status;
              Species                     Stock       strategic (Y/N)    Abundance \2\   Relative occurrence in
                                                            \1\                               project area
----------------------------------------------------------------------------------------------------------------
                      Order Cetartiodactyla--Cetacea--Superfamily Mysticeti (baleen whales)
----------------------------------------------------------------------------------------------------------------
Family: Balaenopteridae
    Humpback whale \3\ (Megaptera               n/a  -/-; N                     12,312  Uncommon.
     novaeangliae).
    Minke whale \4\ (Balaenoptera               n/a  -/-; N                     20,741  Uncommon.
     acutorostrata).
    Bryde's whale (Balaenoptera                 n/a  -/-; N                    unknown  Uncommon.
     brydei).
    Sei whale (Balaenoptera                     n/a  E/D; Y                        357  Uncommon.
     borealis).
    Fin whale \4\ (Balaenoptera                 n/a  E/D; Y                      3,522  Uncommon.
     physalus).

[[Page 27959]]

 
    Blue whale (Balaenoptera                    n/a  E/D; Y                        440  Uncommon.
     musculus).
----------------------------------------------------------------------------------------------------------------
        Order Cetartiodactyla--Cetacea--Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
----------------------------------------------------------------------------------------------------------------
Family: Physeteridae
    Sperm whale (Physeter                       n/a  E/D; Y                      2,288  Uncommon.
     macrocephalus).
        Order Cetartiodactyla--Cetacea--Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
----------------------------------------------------------------------------------------------------------------
Family: Kogiidae
    Pygmy sperm whale \5\ (Kogia                n/a  -/-; N                      3,785  Rare.
     breviceps).
    Dwarf sperm whale \5\ (Kogia                n/a  -/-; N                      3,785  Rare.
     sima).
----------------------------------------------------------------------------------------------------------------
        Order Cetartiodactyla--Cetacea--Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
----------------------------------------------------------------------------------------------------------------
Family delphinidae
    Killer whale (Orcinus orca)....             n/a  -/-; N                    unknown  Uncommon.
    False killer whale (Pseudorca               n/a  -/-; N                        442  Uncommon.
     crassidens).
    Pygmy killer whale (Feresa                  n/a  -/-; N                    unknown  Rare.
     attenuata).
    Short-finned pilot whale                    n/a  -/-; N                     21,515  Uncommon.
     (Globicephala macrorhynchus).
    Long-finned pilot whale                     n/a  -/-; N                      5,636  Uncommon.
     (Globicephala melas).
    Harbor porpoise (Phocoena                   n/a  -/-; N                     79,833  Uncommon.
     phocoena).
    Bottlenose dolphin (Tursiops                n/a  -/-; N                     77,532  Uncommon.
     truncatus).
    Striped dolphin (Stenella                   n/a  -/-; N                     54,807  Uncommon.
     coeruleoala).
    Risso's dolphin (Grampus                    n/a  -/-; N                     18,250  Uncommon.
     griseus).
    Common dolphin \4\ (Delphinus               n/a  -; N                      173,486  Uncommon.
     delphis).
    Atlantic white-sided dolphin                n/a  -; N                       48,819  Uncommon.
     (Lagenorhynchus obliquidens).
    Atlantic spotted dolphin                    n/a  -; N                       44,715  Uncommon.
     (Stenella frontalis).
    Pantropical spotted dolphin                 n/a  -; N                        3,333  Uncommon.
     (Stenella attenuate).
    White beaked dolphin                        n/a  -; N                        2,003  Uncommon.
     (Lagenorhynchus albirostris).
    Rough-toothed dolphin (Steno                n/a  -; N                          271  Rare.
     bredanensis).
----------------------------------------------------------------------------------------------------------------
        Order Cetartiodactyla--Cetacea--Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
----------------------------------------------------------------------------------------------------------------
Family: Ziphiidae
    Cuvier's beaked whale (Ziphius              n/a  -/-; N                      6,532  Uncommon.
     cavirostris).
    Blainville's beaked whale \6\               n/a  -; N                        7,092  Uncommon.
     (Mesoplodon densirostris).
    True's beaked whale \6\                     n/a  -/-; N                      7,092  Rare.
     (Mesoplodon mirus).
    Gervais beaked whale \6\                    n/a  -; N                        7,092  Uncommon.
     (Mesoplodon europaeus).
    Sowerby's beaked whale \6\                  n/a  -; N                        7,092  Uncommon.
     (Mesoplodon bidens).
    Northern bottlenose whale                   n/a  -; N                      unknown  Uncommon.
     (Hyperoodon ampullatus).
----------------------------------------------------------------------------------------------------------------
                                     Order Carnivora--Superfamily Pinnipedia
----------------------------------------------------------------------------------------------------------------
Family Phocidae (earless seals)
    Hooded seal (Cystophora                     n/a  -; N                      592,100  Rare.
     cristata).
    Harp seal (Pagophilus                       n/a  -; N                    7,100,000  Rare.
     groenlandicus).
    Ringed seal (Pusa hispida) \7\.             n/a  -; N                      unknown  Rare.
----------------------------------------------------------------------------------------------------------------
\1\ Endangered Species Act (ESA) status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-)
  indicates that the species is not listed under the ESA or designated as depleted under the MMPA. Under the
  MMPA, a strategic stock is one for which the level of direct human-caused mortality exceeds PBR or which is
  determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or
  stock listed under the ESA is automatically designated under the MMPA as depleted and as a strategic stock.
\2\ Abundance estimates are from the NMFS 2017 draft Atlantic SAR (Hayes et al., 2017) unless otherwise noted.
  We note that marine mammals in the survey area would not belong to NMFS stocks, as the survey area is outside
  the geographic boundaries for stock assessments, thus stock abundance estimates are provided for comparison
  purposes only.
\3\ NMFS defines a stock of humpback whales only on the basis of the Gulf of Maine feeding population; however,
  multiple feeding populations originate from the Distinct Population Segment (DPS) that is expected to occur in
  the proposed survey area (the West Indies DPS). As West Indies DPS whales from multiple feeding populations
  may be encountered in the proposed survey area, the total abundance of the West Indies DPS best reflects the
  abundance of the population that may encountered by the proposed survey. The West Indies DPS abundance
  estimate shown here reflects the latest estimate as described in the NMFS Status Review of the Humpback Whale
  under the Endangered Species Act (Bettridge et al., 2015).
\4\ Abundance for these species is from the 2007 TNASS, which provided full coverage of the Atlantic Canadian
  coast (Lawson and Gosselin, 2009). Abundance estimates from TNASS were corrected for perception and
  availability bias, when possible. In general, where the TNASS survey effort provided superior coverage of a
  stock's range (as compared with NOAA shipboard survey effort), we elect to use the resulting abundance
  estimate over the current NMFS abundance estimate (derived from survey effort with inferior coverage of the
  stock range).
\5\ Abundance estimate represents pygmy and dwarf sperm whales combined.
\6\ Abundance estimate represents all species of Mesoplodon in the Atlantic.
\7\ NMFS does not have a defined stock of ringed seals in the Atlantic Ocean.


[[Page 27960]]

    Four marine mammal species that are listed under the Endangered 
Species Act (ESA) may be present in the survey area and are included in 
the take request: The fin whale, sei whale, blue whale and sperm whale. 
Though marine mammal species other than those described in Table 2 are 
known to occur in the North Atlantic Ocean, the temporal and/or spatial 
occurrence of several of these species is such that take of these 
species is not expected to occur, and they are therefore not discussed 
further beyond the explanation provided here. Four cetacean species, 
although present in the wider North Atlantic Ocean, likely would not be 
found near the proposed project area because their ranges generally do 
not extend as far north: Clymene dolphin, Fraser's dolphin, spinner 
dolphin, and melon-headed whale. Another cetacean species, the North 
Atlantic right whale, occurs in nearshore waters off the U.S. coast, 
and its range does not extend as far offshore as the proposed project 
area. Another three cetacean species occur in arctic waters, and their 
ranges generally do not extend as far south as the proposed project 
area: The bowhead whale, narwhal, and beluga. Two additional cetacean 
species, the Atlantic humpback dolphin (which occurs in coastal waters 
of western Africa) and the long-beaked common dolphin (which occurs in 
coastal waters of South America and western Africa) do not occur in 
deep offshore waters. Several pinniped species also are known to occur 
in North Atlantic waters, but are not expected to occur in deep 
offshore waters of the proposed project area, including the gray seal, 
harbor seal, and bearded seal.
    A detailed description 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 of the proposed IHA (83 FR 18644; April 27, 
2018); since that time, we are not aware of any changes in the status 
of these species and stocks; therefore, detailed descriptions are not 
repeated here. Please refer to that Federal Register notice for these 
descriptions. Please also refer to NMFS' website 
(www.fisheries.noaa.gov/species-directory) for generalized species 
accounts.
    Information concerning marine mammal hearing, including marine 
mammal functional hearing groups, was provided in the Federal Register 
notice of the proposed IHA (83 FR 18644; April 27, 2018), therefore 
that information is not repeated here; please refer to that Federal 
Register notice for this information. For further information about 
marine mammal functional hearing groups and associated frequency 
ranges, please see NMFS (2016) for a review of available information. 
Thirty-three marine mammal species (thirty cetacean and three pinniped 
(all phocid) species) have the reasonable potential to co-occur with 
the proposed survey activities (Table 2). Of the cetacean species that 
may be present, six are classified as low-frequency cetaceans (i.e., 
all mysticete species), twenty-two are classified as mid-frequency 
cetaceans (i.e., all delphinid species, beaked whales, and sperm 
whale), and three are classified as a high-frequency cetaceans (i.e., 
harbor porpoise, pygmy and dwarf sperm whales).

Potential Effects of Specified Activities on Marine Mammals and Their 
Habitat

    The effects of underwater noise from SIO's survey activities have 
the potential to result in behavioral harassment of marine mammals in 
the vicinity of the survey area. The Federal Register notice of the 
proposed IHA (83 FR 18644; April 27, 2018) 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 hearing 
threshold shifts, injury, serious injury, or mortality are expected as 
a result of the planned 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 ``small numbers'' and the negligible impact determination.
    Harassment is the only type of take expected to result from these 
activities. Except with respect to certain activities not pertinent 
here, section 3(18) of the MMPA defines ``harassment'' as any act of 
pursuit, torment, or annoyance which (i) has the potential to injure a 
marine mammal or marine mammal stock in the wild (Level A harassment); 
or (ii) has the potential to disturb a marine mammal or marine mammal 
stock in the wild by causing disruption of behavioral patterns, 
including, but not limited to, migration, breathing, nursing, breeding, 
feeding, or sheltering (Level B harassment).
    Authorized takes would primarily be by Level B harassment, as use 
of the 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. Auditory injury is unlikely to occur for 
low- and mid-frequency cetaceans 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 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 dB re 1 [mu]Pa (rms) for continuous (e.g. 
vibratory pile-

[[Page 27961]]

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 proposed activity includes the use of impulsive 
seismic sources. Therefore, the 160 dB re 1 [mu]Pa (rms) criteria is 
applicable for analysis of level B harassment.
    Level A harassment for non-explosive sources-- NMFS' Technical 
Guidance for Assessing the Effects of Anthropogenic Sound on Marine 
Mammal Hearing (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). As 
described above, SIO's proposed activity includes the use of 
intermittent and impulsive seismic sources. These thresholds are 
provided in Table 3.
    These thresholds are provided in the table 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: 
http://www.nmfs.noaa.gov/pr/acoustics/guidelines.htm.

 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 dB    LE,LF,24h: 199 dB.
                                   LE,LF,24h: 183 dB.
Mid-Frequency (MF) Cetaceans....  Lpk,flat: 230 dB    LE,MF,24h: 198 dB.
                                   LE,MF,24h: 185 dB.
High-Frequency (HF) Cetaceans...  Lpk,flat: 202 dB    LE,HF,24h: 173 dB.
                                   LE,HF,24h: 155 dB.
Phocid Pinnipeds (PW)             Lpk,flat: 218 dB    LE,PW,24h: 201 dB.
 (Underwater).                     LE,PW,24h: 185 dB.
Otariid Pinnipeds (OW)            Lpk,flat: 232 dB    LE,OW,24h: 219 dB.
 (Underwater).                     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 survey would entail the use of a 2-airgun array with a total 
discharge of 90 in\3\ at a tow depth of 2-4 m. The distances to the 
predicted isopleths corresponding to the threshold for Level B 
harassment (160 dB re 1 [mu]Pa) were calculated for both array 
configurations 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 Level B harassment 
isopleths for the two configurations of the Atlantis airgun array are 
shown in Table 4.

 Table 4--Predicted Radial Distances From R/V Atlantis 90 in\3\ Seismic
    Source to Isopleth Corresponding to Level B Harassment Threshold
------------------------------------------------------------------------
                                                             Predicted
                                                            distance to
                   Array configuration                    threshold (160
                                                              dB re 1
                                                              [mu]Pa)
------------------------------------------------------------------------
2 m airgun separation...................................           578 m
8 m airgun separation...................................           539 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 
Figures 2 and 3 in the IHA application). LDEO's modeling methodology is 
described in greater detail in the IHA application (LGL, 2018) and we 
refer to 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 3), were 
calculated based on modeling performed by LDEO using the Nucleus 
software program and the NMFS User Spreadsheet, described below. The 
updated acoustic thresholds for impulsive sounds (such as airguns) 
contained in the Technical Guidance (NMFS, 2016) were presented as dual 
metric acoustic thresholds using both cumulative sound exposure level 
(SELcum) and peak sound pressure level metrics. As dual 
metrics, NMFS considers onset of PTS (Level A harassment) to have 
occurred when either one of the two metrics is exceeded (i.e., metric 
resulting in the largest isopleth). The SELcum metric 
considers both level and duration of exposure, as well as auditory 
weighting functions by marine mammal hearing group. In recognition of 
the fact that the requirement to calculate Level A harassment 
ensonified areas could be more technically challenging to predict due 
to the duration component and the use of weighting functions in the new 
SELcum thresholds, NMFS developed an optional User 
Spreadsheet that includes tools to help predict a simple isopleth that 
can be used in conjunction with marine mammal density or occurrence to 
facilitate the estimation of take numbers.
    The values for SELcum and peak SPL for the Atlantis 
airgun array were derived from calculating the modified farfield 
signature (Table 5). The farfield signature is often used as a 
theoretical

[[Page 27962]]

representation of the source level. To compute the farfield signature, 
the source level is estimated at a large distance below the array 
(e.g., 9 km), and this level is back projected mathematically to a 
notional distance of 1 m from the array's geometrical center. However, 
when the source is an array of multiple airguns separated in space, the 
source level from the theoretical farfield signature is not necessarily 
the best measurement of the source level that is physically achieved at 
the source (Tolstoy et al. 2009). Near the source (at short ranges, 
distances <1 km), the pulses of sound pressure from each individual 
airgun in the source array do not stack constructively, as they do for 
the theoretical farfield signature. The pulses from the different 
airguns spread out in time such that the source levels observed or 
modeled are the result of the summation of pulses from a few airguns, 
not the full array (Tolstoy et al. 2009). At larger distances, away 
from the source array center, sound pressure of all the airguns in the 
array stack coherently, but not within one time sample, resulting in 
smaller source levels (a few dB) than the source level derived from the 
farfield signature. Because the farfield signature does not take into 
account the 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 (dB) for R/V Atlantis 90 in\3\ Airgun Array
----------------------------------------------------------------------------------------------------------------
                                                                                    5-kt survey
                                                                    8-kt survey      with 2-m       5-kt survey
                                          8-kt survey with 8-m       with 8-m         airgun         with 2-m
       Functional hearing group          airgun separation: Peak      airgun        separation:       airgun
                                                 SPLflat            separation:    Peak SPLflat     separation:
                                                                      SELcum                          SELcum
----------------------------------------------------------------------------------------------------------------
Low frequency cetaceans (Lpk,flat: 219  228.8...................             207           232.8           206.7
 dB; LE,LF,24h: 183 dB).
Mid frequency cetaceans (Lpk,flat: 230  N/A.....................           206.7           229.8           206.9
 dB; LE,MF,24h: 185 dB).
High frequency cetaceans (Lpk,flat:     233.....................           207.6           232.9           207.2
 202 dB; LE,HF,24h: 155 dB).
Phocid Pinnipeds (Underwater)           230.....................           206.7           232.8           206.9
 (Lpk,flat: 218 dB; LE,HF,24h: 185 dB).
Otariid Pinnipeds (Underwater)          N/A.....................             203           225.6           207.4
 (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 Atlantis'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 (for the 2 m airgun 
separation survey) and 4.12 m/second (for the 8 m airgun separation 
survey), and a shot interval of 9.72 seconds (for the 2 m airgun 
separation survey) and 12.15 seconds (for the 8 m airgun separation 
survey) (LGL, 2018), potential radial distances to auditory injury 
zones were calculated for SELcum thresholds, for both array 
configurations. 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 (SELcumor Peak 
SPLflat) is used for estimating takes by Level A harassment. 
The weighting functions used are shown in Table 3 of the IHA 
application.

   Table 6--Modeled Radial Distances (m) From R/V Atlantis 90 in\3\ Airgun Array to Isopleths Corresponding to
                                          Level A Harassment Thresholds
----------------------------------------------------------------------------------------------------------------
                                                    8-kt survey                     5-kt survey
                                                     with 8-m       8-kt survey      with 2-m       5-kt survey
  Functional hearing group (Level A harassment        airgun         with 8-m         airgun         with 2-m
                   thresholds)                      separation:       airgun        separation:       airgun
                                                   Peak SPLflat     separation:    Peak SPLflat     separation:
                                                                      SELcum                          SELcum
----------------------------------------------------------------------------------------------------------------
Low frequency cetaceans (Lpk,flat: 219 dB;                  3.08             2.4            4.89             6.5
 LE,LF,24h: 183 dB).............................
Mid frequency cetaceans (Lpk,flat: 230 dB;                     0               0            0.98               0
 LE,MF,24h: 185 dB).............................
High frequency cetaceans (Lpk,flat: 202 dB;            \1\ 35.53               0       \1\ 35.13               0
 LE,HF,24h: 155 dB).............................
Phocid Pinnipeds (Underwater) (Lpk,flat: 218 dB;            4.02               0            5.51             0.1
 LE,HF,24h: 185 dB).............................
Otariid Pinnipeds (Underwater) (Lpk,flat: 232                  0               0            0.48               0
 dB; LE,HF,24h: 203 dB).........................
----------------------------------------------------------------------------------------------------------------
\1\ Distances to isopleths corresponding to Level A harassment threshold for HF cetaceans (peak SPL) have been
  revised from those shown in the proposed IHA based on use of radial distances (vs radii) to estimate Level A
  isopleths for high frequency cetaceans.

    We note that radial distances to isopleths corresponding to the 
Level A harassment threshold for high frequency cetaceans shown in 
Table 6, for the peak SPL metric, are slightly different than the 
distances that were presented in the proposed IHA. The proposed IHA 
presented the radii (versus radial distances) to the Level A isopleth 
for high frequency cetaceans, for the peak SPL metric, as shown in 
Table 6 of the IHA application (the distances to radii are 34.62 m for 
the 2-m airgun separation survey and 34.84 m for the 8-m airgun 
separation survey). However,

[[Page 27963]]

as radial distances to the Level A isopleth for high frequency 
cetaceans, for the peak SPL metric, are slightly larger than the radii, 
we determined that, to be conservative, the radial distances (as shown 
in Table 6) should be used to calculate ensonified areas and to 
estimate take.
    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 proposed seismic survey, 
the User Spreadsheet predicts the closest distance at which a 
stationary animal would not incur PTS if the sound source traveled by 
the animal in a straight line at a constant speed.

Marine Mammal Occurrence

    In this section we provide the information about the presence, 
density, or group dynamics of marine mammals that will inform the take 
calculations. The best available scientific information was considered 
in conducting marine mammal exposure estimates (the basis for 
estimating take). For all cetacean species, densities calculated by 
Mannocci et al. (2017) were used. These represent the most 
comprehensive and recent density data available for cetacean species in 
the survey area. Mannocci et al. (2017) modeled marine mammal densities 
using available line transect survey data and habitat-based covariates 
and extrapolated model predictions to unsurveyed regions, including the 
proposed survey area. The authors considered line transect surveys that 
used two or more protected species observers and met the assumptions of 
the distance sampling methodology as presented by Buckland et al. 
(2001), and included data from shipboard and aerial surveys conducted 
from 1992 to 2014 by multiple U.S. organizations (details provided in 
Roberts et al. (2016)). The data underlying the model predictions for 
the proposed survey area originated from shipboard survey data 
presented in Waring et al. (2008). To increase the success of model 
transferability to new regions, the authors considered biological 
covariates expected to be related directly to cetacean densities 
(Wenger & Olden, 2012), namely biomass and production of epipelagic 
micronekton and zooplankton predicted with the Spatial Ecosystem and 
Population DYnamics Model (SEAPODYM) (Lehodey et al. 2010). Zooplankton 
and epipelagic micronekton (i.e., squid, crustaceans, and fish) 
constitute potential prey for many of the cetaceans considered, in 
particular dolphins and mysticetes (Pauly et al. 1998), and all these 
covariates correlate with cetacean distributions (e.g., Ferguson et al. 
2006; Doniol-Valcroze et al. 2007; Lambert et al. 2014). 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 B harassment or Level A harassment, radial 
distances to predicted isopleths corresponding to the Level A 
harassment and Level B harassment thresholds are calculated, as 
described above (Table 7). Those distances are then used to calculate 
the area(s) around the airgun array predicted to be ensonified to sound 
levels that exceed the Level A and Level B harassment thresholds. The 
areas estimated to be ensonified in a single day of the survey are then 
calculated, based on the areas predicted to be ensonified around the 
array and the estimated trackline distance traveled per day (Table 8). 
This number is then multiplied by the number of survey days (i.e., 7.5 
days for the 5-kt survey with 2-m airgun separation and 17.5 days for 
the 8-kt survey with 8-m airgun separation). The product is then 
multiplied by 1.25 to account for an additional 25 percent contingency 
for potential additional seismic operations due to airgun testing, 
mechanical failure, etc. This results in an estimate of the total areas 
(km\2\) expected to be ensonified to the Level A harassment and Level B 
harassment thresholds. 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). Areas estimated to be 
ensonified over the duration of the survey are shown in Table 9. The 
marine mammals predicted to occur within these respective areas, based 
on estimated densities, are assumed to be incidentally taken. Estimated 
takes for all marine mammal species are shown in Table 10.

                             Table 7--Distances (m) to Isopleths Corresponding to Level A and Level B Harassment Thresholds
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                              Level B                            Level A harassment threshold \1\
                                                            harassment   -------------------------------------------------------------------------------
                                                             threshold
                         Survey                          ----------------  Low frequency   Mid frequency  High frequency      Otariid         Phocid
                                                            All marine       cetaceans       cetaceans       cetaceans       pinnipeds       pinnipeds
                                                              mammals
--------------------------------------------------------------------------------------------------------------------------------------------------------
5-kt survey with 2-m airgun separation..................             539             6.5            0.98       \2\ 35.13            5.51            0.48
8-kt survey with 8-m airgun separation..................             578            3.08               0       \2\ 35.53            4.02               0
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Level A ensonified areas are estimated based on the greater of the distances calculated to Level A isopleths using dual criteria (SELcum and peak
  SPL).
\2\ Distances to isopleths corresponding to Level A harassment threshold for HF cetaceans have been revised from those shown in the proposed IHA based
  on use of radial distances (vs radii) to estimate Level A isopleths for high frequency cetaceans, as described above.


[[Page 27964]]


                         Table 8--Areas (km\2\) Estimated To Be Ensonified to Level A and Level B Harassment Thresholds per Day
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                              Level B                            Level A harassment threshold \1\
                                                            harassment   -------------------------------------------------------------------------------
                                                             threshold
                         Survey                          ----------------  Low frequency   Mid frequency  High frequency      Otariid         Phocid
                                                            All marine       cetaceans       cetaceans       cetaceans       pinnipeds       pinnipeds
                                                              mammals
--------------------------------------------------------------------------------------------------------------------------------------------------------
5-kt survey with 2-m airgun separation..................          240.68            2.90            0.44       \2\ 15.63            2.45            0.21
8-kt survey with 8-m airgun separation..................          412.10            2.19               0       \2\ 25.28            2.86               0
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Level A ensonified areas are estimated based on the greater of the distances calculated to Level A isopleths using dual criteria (SELcum and peak
  SPL).
\2 \ Ensonified areas have been revised from those shown in the proposed IHA based on use of radial distances (vs radii) to estimate Level A isopleths
  for high frequency cetaceans, as described above.
Note: Estimated areas shown for single day do not include additional 25 percent contingency.


                 Table 9--Areas (km\2\) Estimated To Be Ensonified to Level A and Level B Harassment Thresholds Over Duration of Survey
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                              Level B                            Level A harassment threshold \1\
                                                            harassment   -------------------------------------------------------------------------------
                                                             threshold
                         Survey                          ----------------  Low frequency   Mid frequency  High frequency      Otariid         Phocid
                                                            All marine       cetaceans       cetaceans       cetaceans       pinnipeds       pinnipeds
                                                              mammals
--------------------------------------------------------------------------------------------------------------------------------------------------------
5-kt survey with 2-m airgun separation..................         2256.33           27.10            4.09       \2\146.57           22.97             2.0
8-kt survey with 8-m airgun separation..................         9014.56           47.84               0       \2\552.93           62.50               0
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Level A ensonified areas are estimated based on the greater of the distances calculated to Level A isopleths using dual criteria (SELcum and peak
  PL).
\2\ Ensonified areas have been revised from those shown in the proposed IHA based on use of radial distances (vs radii) to estimate Level A isopleths
  for high frequency cetaceans, as described above.
Note: Estimated areas shown include additional 25 percent contingency.


                                       Table 10--Numbers of Potential Incidental Take of Marine Mammals Authorized
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                               Total
                                                                                                                                           instances of
                                            Density (#/      Estimated      Authorized       Estimated      Authorized      Total takes     takes as a
                 Species                   1,000 km \2\)   Level A takes   Level A takes   Level B takes   Level B takes    authorized     percentage of
                                                                                                                                           SAR abundance
                                                                                                                                                \1\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Humpback whale \2\......................              10               1               0             112             113             113           * 0.9
Minke whale.............................               4               0               0              45              45              45           * 0.2
Bryde's whale...........................             0.1               0               0               1               1               1         unknown
Sei whale \2\...........................              10               1               0             112             113             113            31.4
Fin whale...............................               8               1               0              89              90              90           * 2.6
Blue whale..............................               0               0               0               0               1               1             0.2
Sperm whale.............................              40               0               0             451             451             451            19.7
Cuvier's beaked whale \3\...............              60               0               0             135             135             135             2.0
Northern bottlenose whale \4\...........             0.8               0               0               9               9               9         unknown
True's beaked whale \3\.................              60               0               0             135             135             135             1.9
Gervais beaked whale \3\................              60               0               0             135             135             135             1.9
Sowerby's beaked whale \3\..............              60               0               0             135             135             135             1.9
Blainville's beaked whale \3\...........              60               0               0             135             135             135             1.9
Rough-toothed dolphin...................               3               0               0              34              34              34            12.5
Bottlenose dolphin \4\..................              60               0               0             676             676             676             0.9
Pantropical spotted dolphin.............              10               0               0             113             113             113             3.4
Atlantic spotted dolphin................              40               0               0             451             451             451             1.0
Striped dolphin.........................              80               0               0             902             902             902             1.6
Atlantic white-sided dolphin \4\........              60               0               0             676             676             676             1.4
White-beaked dolphin....................               1               0               0              11              11              11             0.6
Common dolphin..........................             800               3               0            9014            9017            9017           * 5.2
Risso's dolphin \4\.....................              20               0               0             225             225             225             1.2
Pygmy killer whale \5\..................             1.5               0               0              17              17              17         unknown
False killer whale......................               2               0               0              23              23              23             5.2
Killer whale \ 5 6\.....................             0.2               0               0               2               5               5         unknown

[[Page 27965]]

 
Long-finned/short-finned Pilot whale \               200               1               0            2253            2254            2254             8.3
 7\.....................................
Pygmy/dwarf sperm whale.................             0.6               0               0               7               7               7             0.2
Harbor porpoise \8\.....................              60              42              42             634             634             676             0.8
Ringed seal \5\.........................               0               0               0               0               1               1         unknown
Hooded seal.............................               0               0               0               0               1               1            <0.1
Harp seal...............................               0               0               0               0               1               1            <0.1
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1 \ While we have in most cases provided comparisons of the instances of takes as a percentage of SAR abundance as the best available information
  regarding population abundance, we note that these are likely underestimates of the relevant North Atlantic populations, as the proposed survey area
  is outside the U.S. EEZ.
* Instances of takes are shown as a percentage of abundance as described by TNASS or NMFS Status Review, as described above.
\2\ Level A takes of these species were estimated based on NMFS' take calculation methodology, but NMFS has determined Level A take of these species is
  not likely to occur, as described in more detail in the text below. To avoid undercounting the takes estimated to occur, the number of takes by Level
  A harassment that had been estimated for these species, but that NMFS has determined are unlikely to occur as described below, are therefore assumed
  to be Level B harassment takes. Thus the number of Level A harassment takes that had been calculated for these species has been added to the number of
  Level B takes authorized for the species.
\3\ Density value represents the density for all beaked whale species combined. Requested take and take authorized are based on the proportion of all
  beaked whales expected to be taken (thus 677 total estimated beaked whale takes were calculated based on the density of all beaked whales combined,
  and this number has been divided by 5 (for the 5 species of beaked whales expected to be taken) for a total of 135 takes per species of beaked whale.
\4\ Number of take authorized has been revised slightly from that shown in proposed IHA due to math error.
\5\ The population abundance for the species is unknown.
\6\ Authorized take number for killer whales has been increased from the calculated take to mean group size for the species. Source for mean group size
  is Waring et al. (2008).
\7\ Values for density, take number, and percentage of population authorized are for short-finned and long-finned pilot whales combined.
\8\ Number of Level A and Level B takes authorized is slightly different than shown in proposed IHA due to use of radial distance (vs radii) to level A
  isopleth as described above.

    For some marine mammal species, we authorize a different number of 
incidental takes than the number of incidental takes requested by SIO 
(see Table 8 in the IHA application for requested take numbers). For 
instance, SIO requested 1 take of a North Atlantic right whale and 3 
takes of bowhead whales; however, we have determined the likelihood of 
the survey encountering these species is so low as to be discountable, 
therefore we do not authorize takes of these species. Also, SIO 
requested Level A takes of humpback whales, sei whales, fin whales, 
common dolphins, and pilot whales; however, due to very small zones 
corresponding to Level A harassment for low-frequency and mid-frequency 
cetaceans (Table 6) we have determined the likelihood of Level A take 
occurring for species from these functional hearing groups is so low as 
to be discountable, therefore we do not authorize Level A take of these 
species. Note that the Level A takes that were calculated for these 
species (humpback whales, sei whales, fin whales, common dolphins, and 
pilot whales) have been included in the number of Level B takes. 
Finally, SIO requested 2,254 takes of short-finned pilot whales and 
2,254 takes of long-finned pilot whales (total 4,508 pilot whale takes 
requested); however, as Mannocci et al. (2017) presents one single 
density estimate for all pilot whales (the pilot whale ``guild''), a 
total of 2,254 takes of pilot whales were calculated as potentially 
taken by the proposed survey. Thus SIO's request take number is 
actually double the number of take that was calculated. We do not think 
doubling the take estimate is warranted, thus we authorize a total of 
2,254 takes of pilot whales (short-finned and long-finned pilot whales 
combined). We note that numbers of take authorized for bottlenose 
dolphin, Atlantic white-sided dolphin, and Risso's dolphin have changed 
slightly (each has been reduced by one take) from the numbers of take 
presented in the proposed IHA due to a math error. We note also that 
the number of instances of authorized Level A take of harbor porpoise 
has increased by one, and the number of instances of authorized Level B 
take of harbor porpoise has decreased by one, versus the numbers of 
take presented in the proposed IHA, due to the slight change in the 
estimate of the Level A ensonified area for high frequency cetaceans as 
described above; the total number of harbor porpoise takes has not 
changed from the total presented in the proposed IHA.
    Species with Take Estimates Less than Mean Group Size: Using the 
approach described above to estimate take, the take estimate for killer 
whales was less than the average group size estimated for the species 
(Waring et al., 2008). Information on the social structure and life 
history of the species indicates it is common for the species to be 
encountered in groups. The results of take calculations support the 
likelihood that SIO's survey may encounter and incidentally take the 
species, and we believe it is likely that the species may be 
encountered in groups; therefore it is reasonable to conservatively 
assume that one group of the species will be taken during the proposed 
survey. We therefore authorize the take of the average (mean) group 
size for the species to account for the possibility that SIO's survey 
encounters a group of killer whales.
    Species with No Available Density Data: No density data were 
available for the blue whale; however, blue whales have been observed 
in the survey area (Waring et al., 2008), thus we determined there is a 
possibility that the proposed survey may encounter one blue whale and 
that one blue whale may be taken by Level B harassment by the proposed 
survey; we therefore authorize one take of blue whale as requested by

[[Page 27966]]

SIO. No density data were available for ringed seal, hooded seal or 
harp seal; however based on the ranges of these species we have 
determined it is possible they may be encountered and taken by Level B 
harassment by the proposed survey, therefore we authorize one take of 
each species as requested by SIO.
    It should be noted that the take numbers shown in Table 10 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 
proposed 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.

Mitigation

    In order to issue an IHA under Section 101(a)(5)(D) of the MMPA, 
NMFS must set forth the permissible methods of taking pursuant to such 
activity, and other means of effecting the least practicable impact on 
such species or stock and its habitat, paying particular attention to 
rookeries, mating grounds, and areas of similar significance, and on 
the availability of such species or stock for taking for certain 
subsistence uses (latter not applicable for this action). NMFS 
regulations require applicants for incidental take authorizations to 
include information about the availability and feasibility (economic 
and technological) of equipment, methods, and manner of conducting such 
activity or other means of effecting the least practicable adverse 
impact upon the affected species or stocks and their habitat (50 CFR 
216.104(a)(11)).
    In evaluating how mitigation may or may not be appropriate to 
ensure the least practicable adverse impact on species or stocks and 
their habitat, as well as subsistence uses where applicable, we 
carefully consider two primary factors:

    (1) The manner in which, and the degree to which, the successful 
implementation of the measure(s) is expected to reduce impacts to 
marine mammals, marine mammal species or stocks, and their habitat. 
This considers the nature of the potential adverse impact being 
mitigated (likelihood, scope, range). It further considers the 
likelihood that the measure will be effective if implemented 
(probability of accomplishing the mitigating result if implemented as 
planned) the likelihood of effective implementation (probability 
implemented as planned); and
    (2) The practicability of the measures for applicant 
implementation, which may consider such things as cost, impact on 
operations, and, in the case of a military readiness activity, 
personnel safety, practicality of implementation, and impact on the 
effectiveness of the military readiness activity.
    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 has proposed to implement the 
following mitigation measures for marine mammals:

    (1) Vessel-based visual mitigation monitoring;
    (2) Establishment of a marine mammal exclusion zone (EZ);
    (3) Shutdown procedures;
    (4) Ramp-up procedures; and
    (5) Vessel strike avoidance measures.
    In addition to the measures proposed by SIO, NMFS has incorporated 
the following mitigation measure: Establishment of a marine mammal 
buffer zone.
    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 
Atlantis 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 EZ (as described below).
    During seismic operations, three visual PSOs will be based aboard 
the Atlantis. 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 Atlantis is a suitable platform from which PSOs will watch for 
marine mammals. 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 will 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

[[Page 27967]]

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 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 
Shutdown 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 injury 
criteria for all marine mammal hearing groups (Table 6) while also 
providing a consistent, reasonably observable zone within which PSOs 
would typically be able to conduct effective observational effort. In 
this case, the 100 m radial distance would also be expected to contain 
sound that would exceed the Level A harassment threshold based on sound 
exposure level (SELcum) criteria for all marine mammal 
hearing groups (Table 6). In the 2011 Programmatic Environmental Impact 
Statement for marine scientific research funded by the National Science 
Foundation 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 EZ 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 EZ) 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.

Shutdown Procedures

    If a marine mammal is detected outside the EZ but is likely to 
enter the EZ, the airguns will be shut down before the animal is within 
the EZ. Likewise, if a marine mammal is already within the EZ when 
first detected, the airguns will be shut down immediately.
    Following a shutdown, airgun activity will not resume until the 
marine mammal has cleared the 100 m EZ. The animal will be considered 
to have cleared the 100 m EZ if the following conditions have been met:
     It is visually observed to have departed the 100 m EZ; or
     it has not been seen within the 100 m EZ for 15 min in the 
case of small odontocetes and pinnipeds; or
     it has not been seen within the 100 m EZ for 30 min in the 
case of mysticetes and large odontocetes, including sperm, pygmy and 
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, Steno, Stenella, Lagenorhynchus and Delphinus--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 the Federal Register notice of proposed IHA (83 FR 
18644; April 27, 2018) 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 
Atlantis 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.
    Shutdown of the acoustic source will also be required upon 
observation of any of the following:
     A large whale (i.e., sperm whale or any baleen whale) with 
a calf observed at any distance;
     an aggregation of six or more 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.) observed at any distance; 
or

[[Page 27968]]

     a species for which authorization has not been granted, 
or, a species for which authorization has been granted but the 
authorized number of takes are met, observed approaching or within the 
Level A or B harassment zone.

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.
    At least two PSOs will be required to monitor during ramp-up. 
During ramp up, the PSOs will monitor the EZ, and if marine mammals 
were observed within the EZ or buffer zone, 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 is 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.

Vessel Strike Avoidance Measures

    Vessel strike avoidance measures are intended to minimize the 
potential for collisions with marine mammals. These requirements do not 
apply in any case where compliance creates an imminent and serious 
threat to a person or vessel or to the extent that a vessel is 
restricted in its ability to maneuver and, because of the restriction, 
cannot comply.
    The measures include the following: Vessel operator and crew will 
maintain a vigilant watch for all marine mammals and slow down or stop 
the vessel or alter course to avoid striking any marine mammal. A 
visual observer aboard the vessel will monitor a vessel strike 
avoidance zone around the vessel according to the parameters stated 
below. Visual observers monitoring the vessel strike avoidance zone 
will be either third-party observers or crew members, but crew members 
responsible for these duties will be provided sufficient training to 
distinguish marine mammals from other phenomena. Vessel strike 
avoidance measures will be followed during surveys and while in 
transit.
    The vessel will maintain a minimum separation distance of 100 m 
from large whales (i.e., baleen whales and sperm whales). If a large 
whale is within 100 m of the vessel the vessel will reduce speed and 
shift the engine to neutral, and will not engage the engines until the 
whale has moved outside of the vessel's path and the minimum separation 
distance has been established. If the vessel is stationary, the vessel 
will not engage engines until the whale(s) has moved out of the 
vessel's path and beyond 100 m. The vessel will maintain a minimum 
separation distance of 50 m from all other marine mammals (with the 
exception of delphinids of the genera Tursiops, Steno, Stenella, 
Lagenorhynchus and Delphinus that approach the vessel, as described 
above). If an animal is encountered during transit, the vessel will 
attempt to remain parallel to the animal's course, avoiding excessive 
speed or abrupt changes in course. Vessel speeds will be reduced to 10 
knots or less when mother/calf pairs or large assemblages of cetaceans 
(what constitutes ``large'' will vary depending on species) are 
observed within 500 m of the vessel. Mariners may use professional 
judgment as to when such circumstances warranting additional caution 
are present.
    Based on our evaluation of the applicant's proposed measures, NMFS 
has determined that the mitigation measures provide the means effecting 
the least practicable impact on the affected species or stocks and 
their habitat, paying particular attention to rookeries, mating 
grounds, and areas of similar significance.

Monitoring and Reporting

    In order to issue an IHA for an activity, Section 101(a)(5)(D) of 
the MMPA states that NMFS must set forth, requirements pertaining to 
the monitoring and reporting of such taking. The MMPA implementing 
regulations at 50 CFR 216.104 (a)(13) indicate that requests for 
authorizations must include the suggested means of accomplishing the 
necessary monitoring and reporting that will result in increased 
knowledge of the species and of the level of taking or impacts on 
populations of marine mammals that are expected to be present in the 
proposed action area. Effective reporting is critical both to 
compliance as well as ensuring that the most value is obtained from the 
required monitoring.
    Monitoring and reporting requirements prescribed by NMFS should 
contribute to improved understanding of one or more of the following:
     Occurrence of marine mammal species or stocks in the area 
in which take is anticipated (e.g., presence, abundance, distribution, 
density);
     Nature, scope, or context of likely marine mammal exposure 
to potential stressors/impacts (individual or cumulative, acute or 
chronic), through better understanding of: (1) Action or environment 
(e.g., source characterization, propagation, ambient noise); (2) 
affected species (e.g., life history, dive patterns); (3) co-occurrence 
of marine mammal species with the action; or (4) biological or 
behavioral context of exposure (e.g., age, calving or feeding areas);
     Individual marine mammal responses (behavioral or 
physiological) to acoustic stressors (acute, chronic, or cumulative), 
other stressors, or cumulative impacts from multiple stressors;

[[Page 27969]]

     How anticipated responses to stressors impact either: (1) 
Long-term fitness and survival of individual marine mammals; or (2) 
populations, species, or stocks;
     Effects on marine mammal habitat (e.g., marine mammal prey 
species, acoustic habitat, or other important physical components of 
marine mammal habitat); and
     Mitigation and monitoring effectiveness.
    SIO submitted a marine mammal monitoring and reporting plan in 
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 Atlantis. 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) and with the naked eye. At night, PSOs will be 
equipped with night-vision equipment.
    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; and
    (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 (e.g., 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 survey. 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 and 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's implementing 
regulations (54 FR 40338; September 29, 1989), the impacts from other 
past and ongoing anthropogenic activities are incorporated into this 
analysis via their impacts on the environmental baseline (e.g., as 
reflected in the regulatory status of the species, population size and 
growth rate where known, ongoing sources of human-caused mortality, or 
ambient noise levels).
    To avoid repetition, our analysis applies to all the species listed 
in Table 2, 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 10) for one species. However, we believe

[[Page 27970]]

that any PTS incurred in marine mammals as a result of the planned 
activity would be in the form of only a small degree of PTS and not 
total deafness that would not be likely to affect the fitness of any 
individuals, because of the constant movement of both the Atlantis and 
of the marine mammals in the project area, as well as the fact that the 
vessel is not expected to remain in any one area in which individual 
marine mammals would be expected to concentrate for an extended period 
of time (i.e., since the duration of exposure to loud sounds will be 
relatively short). Also, as described above, we expect that marine 
mammals would be likely to move away from a sound source that 
represents an aversive stimulus, especially at levels that would be 
expected to result in PTS, given sufficient notice of the Atlantis's 
approach due to the vessel's relatively low speed when conducting 
seismic surveys. We expect that the majority of takes would be in the 
form of short-term Level B behavioral harassment in the form of 
temporary avoidance of the area or decreased foraging (if such activity 
were occurring), reactions that are considered to be of low severity 
and with no lasting biological consequences (e.g., Southall et al., 
2007).
    Potential impacts to marine mammal habitat were discussed 
previously in this document (see Potential Effects of the Specified 
Activity on Marine Mammals and their Habitat). Marine mammal habitat 
may be impacted by elevated sound levels, but these impacts would be 
temporary. 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 feeding, mating or calving areas known to be 
biologically important to marine mammals within the proposed project 
area.
    As described above, though marine mammals in the survey area would 
not be assigned to NMFS stocks, for purposes of the small numbers 
analysis we rely on stock numbers from the U.S. Atlantic SARs as the 
best available information on the abundance estimates for the species 
of marine mammals that could be taken. The activity is expected to 
impact a very small percentage of all marine mammal populations that 
would be affected by SIO's planned survey (less than 32 percent each 
for all marine mammal stocks, when compared with stocks from the U.S. 
Atlantic as described above). Additionally, the acoustic ``footprint'' 
of the proposed survey would be very small relative to the ranges of 
all marine mammals that would potentially be affected. Sound levels 
would increase in the marine environment in a relatively small area 
surrounding the vessel compared to the range of the marine mammals 
within the proposed survey area. The seismic array would be active 24 
hours per day throughout the duration of the proposed survey. However, 
the very brief overall duration of the proposed survey (25 days) would 
further limit potential impacts that may occur as a result of the 
proposed activity.
    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 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: fin, sei, blue, and sperm whales. There are 
currently insufficient data to determine population trends for these 
species (Hayes et al., 2017); however, we are authorizing very small 
numbers of takes for these species (Table 10), relative to their 
population sizes (again, when compared to U.S. Atlantic stocks, for 
purposes of comparison only), 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; 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 due to SIO's 
seismic survey would 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. Marine mammals 
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 species or stock through 
effects on annual rates of recruitment or survival:
     No mortality is anticipated or authorized;
     The anticipated impacts of the proposed activity on marine 
mammals would primarily be temporary behavioral changes due to 
avoidance of the area around the survey vessel. The relatively short 
duration of the proposed survey (25 days) would further limit the 
potential impacts of any temporary behavioral changes that would occur;
     The number of instances of PTS that may occur are expected 
to be very small in number (Table 10). Instances of PTS that are 
incurred in marine mammals would be of a low level, due to constant 
movement of the vessel and of the marine mammals in the area, and the 
nature of the survey design (not concentrated in areas of high marine 
mammal concentration);
     The availability of alternate areas of similar habitat 
value for marine mammals to temporarily vacate the survey area during 
the proposed survey to avoid exposure to sounds from the activity;
     The proposed project area does not contain areas of 
significance for feeding, mating or calving;
     The potential adverse effects on fish or invertebrate 
species that serve as prey species for marine mammals from the proposed 
survey would be temporary and spatially limited; and
     The mitigation measures, including visual and acoustic 
monitoring and shutdowns, are expected to minimize potential impacts to 
marine mammals.

[[Page 27971]]

    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 
specified activity will have a negligible impact on all affected marine 
mammal species or stocks.

Small Numbers

    As noted above, only small numbers of incidental take may be 
authorized under Section 101(a)(5)(D) of the MMPA for specified 
activities other than military readiness activities. The MMPA does not 
define small numbers and so, in practice, where estimated numbers are 
available, NMFS compares the number of individuals taken to the most 
appropriate estimation of abundance of the relevant species or stock in 
our determination of whether an authorization is limited to small 
numbers of marine mammals. Additionally, other qualitative factors may 
be considered in the analysis, such as the temporal or spatial scale of 
the activities.
    Due to the location of SIO's survey, some of the marine mammals 
potentially taken by the proposed survey would not be expected to 
originate from the U.S. Atlantic stocks as defined by NMFS (Hayes et 
al., 2017). Population abundance data for marine mammal species in the 
survey area is not available. Therefore, in most cases the U.S. 
Atlantic SARs represent the best available information on marine mammal 
abundance in the Northwest Atlantic Ocean. For certain species (i.e., 
fin whale, minke whale and common dolphin) the 2007 Canadian Trans-
North Atlantic Sighting Survey (TNASS), which provided full coverage of 
the Atlantic Canadian coast (Lawson and Gosselin, 2009) represents the 
best available information on abundance, as noted previously. Abundance 
estimates from TNASS were corrected for perception and availability 
bias, when possible. In general, where the TNASS survey effort provided 
more extensive coverage of a stock's range (as compared with NOAA 
shipboard survey effort), we elected to use the resulting abundance 
estimate over the current NMFS abundance estimate (derived from survey 
effort with more limited coverage of the stock range). For the humpback 
whale, NMFS defines a stock of humpback whales in the Atlantic only on 
the basis of the Gulf of Maine feeding population; however, multiple 
feeding populations originate from the DPS of humpback whales that is 
expected to occur in the proposed survey area (the West Indies DPS). As 
West Indies DPS whales from multiple feeding populations may be 
encountered in the proposed survey area, the total abundance of the 
West Indies DPS best reflects the abundance of the population that may 
encountered by the proposed survey. The West Indies DPS abundance 
estimate used here reflects the latest estimate as described in the 
NMFS Status Review of the Humpback Whale under the Endangered Species 
Act (Bettridge et al., 2015). Therefore, we use abundance data from the 
SARs in most cases, as well as from the TNASS and NMFS Status Review, 
for purposes of the small numbers analysis.
    The numbers of takes that we authorize are less than 10 percent of 
the population abundance for the majority of species and stocks, and 20 
percent for sperm whales and 31 percent for fin whales, when compared 
to abundance estimates from U.S. Atlantic SARs and TNASS and NMFS 
Status Review (Table 10). We again note that while some animals from 
U.S. stocks may occur in the proposed survey area, the proposed survey 
area is outside the geographic boundaries of the U.S. Atlantic SARs, 
thus populations of marine mammals in the proposed survey area would 
not be limited to the U.S. stocks and those populations may in fact be 
larger than the U.S. stock abundance estimates. In addition, it should 
be noted that take numbers represent instances of take, not individuals 
taken. Given the relatively small survey grids (Figure 1 in the IHA 
application), it is reasonable to expect that some individuals may be 
exposed more than one time, which would mean that the number of 
individuals taken is somewhat smaller than the total instances of take 
indicated in Table 10.
    No known current regional population estimates are available for 
five marine mammal species that could be incidentally taken as a result 
of the planned survey: the Bryde's whale, killer whale, pygmy killer 
whale, Northern bottlenose whale, and ringed seal. NMFS has reviewed 
the geographic distributions of these species in determining whether 
the numbers of takes authorized are likely to represent small numbers. 
Bryde's whales are distributed worldwide in tropical and sub-tropical 
waters (Kato and Perrin, 2009). Killer whales are broadly distributed 
in the Atlantic from the Arctic ice edge to the West Indies (Waring et 
al., 2015). The pygmy killer whale is distributed worldwide in tropical 
to sub-tropical waters (Jefferson et al. 1994). Northern bottlenose 
whales are distributed in the North Atlantic from Nova Scotia to about 
70[deg] N in the Davis Strait, along the east coast of Greenland to 
77[deg] N and from England, Norway, Iceland and the Faroe Islands to 
the south coast of Svalbard (Waring et al., 2015). The harp seal occurs 
throughout much of the North Atlantic and Arctic Oceans (Lavigne and 
Kovacs 1988). Based on the broad spatial distributions of these species 
relative to the areas where the proposed survey would occur, NMFS 
concludes that the authorized take of these species represent small 
numbers relative to the affected species' overall population sizes, 
though we are unable to quantify the authorized take numbers as a 
percentage of population.
    Based on the analysis contained herein of the specified 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 would 
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 ESA 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 is authorizing the 
incidental take of 4 species of marine mammals which are listed under 
the ESA: The sei whale, fin whale, blue whale and sperm whale. Under 
Section 7 of the ESA, we requested initiation of Section 7 consultation 
with the NMFS OPR Interagency Cooperation Division for the issuance of 
this IHA. In June, 2018, the NMFS OPR Interagency Cooperation Division 
issued a Biological Opinion with an incidental take statement, which 
concluded that the issuance of

[[Page 27972]]

the IHA was not likely to jeopardize the continued existence of the 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 SIO for the potential harassment of small 
numbers of 35 marine mammal species incidental to a low-energy marine 
geophysical survey in the northwest Atlantic Ocean, provided the 
previously mentioned mitigation, monitoring and reporting requirements 
are incorporated.

    Dated: June 12, 2018.
Donna S. Wieting,
Director, Office of Protected Resources, National Marine Fisheries 
Service.
[FR Doc. 2018-12907 Filed 6-14-18; 8:45 am]
BILLING CODE 3510-22-P