Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to a Low-Energy Geophysical Survey in the Southwest Atlantic Ocean, 54849-54867 [2019-22285]

Agencies

• DEPARTMENT OF COMMERCE
• National Oceanic and Atmospheric Administration

[Federal Register Volume 84, Number 198 (Friday, October 11, 2019)]
[Notices]
[Pages 54849-54867]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2019-22285]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

RIN 0648-XR007


Takes of Marine Mammals Incidental to Specified Activities; 
Taking Marine Mammals Incidental to a Low-Energy Geophysical Survey in 
the Southwest 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 Institute of Oceanography (SIO) to incidentally harass, by 
Level A and Level B harassment, marine mammals during a low-energy 
marine geophysical survey in the Southwest Atlantic Ocean.

DATES: This Authorization is effective from September 12, 2019 through 
September 11, 2020.

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

SUPPLEMENTARY INFORMATION:

Background

    The MMPA prohibits the ``take'' of marine mammals, with certain 
exceptions. Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 
et seq.) direct the Secretary of Commerce (as delegated to NMFS) to 
allow, upon request, the incidental, but not intentional, taking of 
small numbers of marine mammals by U.S. citizens who engage in a 
specified activity (other than commercial fishing) within a specified

[[Page 54850]]

geographical region if certain findings are made and either regulations 
are issued or, if the taking is limited to harassment, a notice of a 
proposed incidental take authorization may be provided to the public 
for review.
    Authorization for incidental takings shall be granted if NMFS finds 
that the taking will have a negligible impact on the species or 
stock(s) and will not have an unmitigable adverse impact on the 
availability of the species or stock(s) for taking for subsistence uses 
(where relevant). Further, NMFS must prescribe the permissible methods 
of taking and other ``means of effecting the least practicable adverse 
impact'' on the affected species or stocks and their habitat, paying 
particular attention to rookeries, mating grounds, and areas of similar 
significance, and on the availability of such species or stocks for 
taking for certain subsistence uses (referred to in shorthand as 
``mitigation''); and requirements pertaining to the mitigation, 
monitoring and reporting of such takings are set forth.

Summary of Request

    On March 13, 2019, NMFS received a request from SIO for an IHA to 
take marine mammals incidental to conducting a low-energy marine 
geophysical survey in the Southwest Atlantic Ocean. The application was 
deemed adequate and complete on May 20, 2019. SIO's request was for 
take of a small number of 49 species of marine mammals by Level B 
harassment. Neither SIO nor NMFS expects serious injury or mortality to 
result from this activity and, therefore, an IHA is appropriate.

Description of Specified Activity

    SIO plans to conduct low-energy marine seismic surveys in the 
Southwest Atlantic Ocean during September-October 2019. The seismic 
surveys would be conducted in the Exclusive Economic Zone (EEZ) of the 
Falkland Islands and International Waters, with water depths ranging 
from ~50-5700 meters (m) (See Figure 1 in the IHA application). A total 
of ~7,500 kilometers (km) of seismic data would be collected. The 
surveys would involve one source vessel, R/V Thomas G. Thompson (R/V 
Thompson). The Thompson would deploy up to two 45-in\3\ GI airguns at a 
depth of 2-4 m with a maximum total volume of ~90 in\3\. The receiving 
system would consist of one hydrophone streamer, 200-1,600 m in length, 
which would receive the returning acoustic signals and transfer the 
data to the on-board processing system.
    The airgun array would be operated in one of two different types of 
array modes. The first would be highest-quality survey mode to collect 
the highest-quality seismic reflection data at approximately 18 
potential drill sites. The second mode would be a reconnaissance mode, 
which is quicker, and will occur at approximately 75 coring locations, 
primarily in Survey Area 2 (see Figure 1 in the IHA application). The 
reconnaissance mode also allows for operations to occur in poor weather 
where the use of streamer longer than 200-m may not be possible safely.
    The reconnaissance mode is carried out using either one or two 45-
in\3\ airguns, with airguns spaced 8 m apart (if 2 are being used) at a 
water depth of 2-4 m, with a 200 m hydrophone streamer and with the 
vessel traveling at 8 knots (kn). The highest-quality mode is carried 
out using a pair of 45-in\3\ airguns, with airguns spaced 2 m apart at 
a depth of 2-4 m, with a 400, 800, or 1,600 m hydrophone streamer and 
with the vessel traveling at to 5 kn to achieve high-quality seismic 
reflection data.

Comments and Responses

    A notice of NMFS's proposal to issue an IHA to SIO was published in 
the Federal Register on August 12, 2019 (84 FR 39896). That notice 
described, in detail, SIO's activity, the marine mammal species that 
may be affected by the activity, and the anticipated effects on marine 
mammals. During the 30-day public comment period, NMFS received comment 
letters from the Marine Mammal Commission (Commission) and Falklands 
Conservation, and a comment from the Falkland Islands Director of 
Natural Resources.
    Comment 1: The Commission recommended NMFS specify why it believes 
that sound channels with downward refraction, as well as seafloor 
refractions, are not likely to occur during SIO's survey and the degree 
to which both of these parameters would affect the estimation (or 
underestimation) of Level B harassment zones in deep and intermediate 
water depths. Additionally, the Commission recommended NMFS specify how 
it has validated use of Lamont-Doherty Earth Observatory's (L-DEO's) 
acoustic modeling correction factors and ratios to account for 
differing water depths, tow depths, and airgun spacing for surveys that 
occur in both intermediate and shallow water.
    Response: The L-DEO approach to the modeling is generally 
conservative as supported by data collected from calibration and other 
field data along with modeling results. The L-DEO approach does not 
rely on incorporating every possible environmental factor in the marine 
environment. Published results from Tolstoy (2009), Diebold (2010), and 
Crone et al. (2014, 2017), along with nearly 20 years of PSO 
observations from previous NSF-funded seismic surveys in various water 
depths validate the approach. L-DEO has presented their modeling 
approach to NMFS and the Commission on several occasions. Given the 
information presented, numerous discussions, and observations from past 
NSF-funded seismic surveys that used the L-DEO modeling approach, NMFS 
remains confident that the methodology used is appropriate and 
conservatively protects marine mammals.
    Comment 2: The Commission noted tables depicting source levels in 
both the IHA application and the Federal Register notice contained 
inadequate information and that the appendices of SIO's IHA application 
did not contain necessary information. The Commission recommended that 
NMFS ensure that all source levels, modified source levels, and related 
adjustment factors are specified and all relevant isopleth figures and 
user spreadsheet tables are included in all future NSF-funded and -
affiliated applications prior to processing them.
    Response: NMFS has added clarification on the tables noted by the 
Commission and provided the Commission the requested information. NMFS 
will ensure that all applications contain the necessary information 
required for adequate understanding of the acoustic modeling prior to 
publishing the notice of proposed IHA.
    Comment 3: The Commission recommended that, instead of using the L-
DEO modeling described in the IHA application, NMFS require SIO to re-
estimate the proposed Level A and Level B harassment zones and 
associated takes of marine mammals using (1) both operational 
(including number/type/spacing of airguns, tow depth, source level/
operating pressure, operational volume) and site-specific environmental 
(including sound speed profiles, bathymetry, and sediment 
characteristics at a minimum) parameters, (2) a comprehensive source 
model (i.e., Gundalf Optimizer or AASM) and (3) an appropriate sound 
propagation model for the proposed incidental harassment authorization. 
Specifically, the Commission reiterates that L-DEO should be using the 
ray-tracing propagation model BELLHOP--which is a free, standard 
propagation code that readily incorporates all environmental inputs 
listed herein, rather than the limited, in-house

[[Page 54851]]

MATLAB code currently in use, and recommends NMFS specify why it 
believes that L-DEO's modeling approaches provide more accurate, 
realistic, and appropriate Level A and Level B harassment zones than 
BELLHOP.
    Response: NMFS acknowledges the Commission's concerns about L-DEO's 
current modeling approach for estimating Level A and Level B harassment 
zones and takes. SIO's application and the Federal Register notice of 
the proposed IHA (84 FR 39896; August 12, 2019) describe the 
applicant's approach to modeling Level A and Level B harassment zones. 
The model L-DEO currently uses does not allow for the consideration of 
environmental and site-specific parameters as requested by the 
Commission, but as described below, field measurements support the use 
of the model used.
    SIO's application describes L-DEO's approach to modeling Level A 
and Level B harassment zones. In summary, L-DEO acquired field 
measurements for several array configurations at shallow, intermediate, 
and deep-water depths during acoustic verification studies conducted in 
the northern Gulf of Mexico in 2007 and 2008 (Tolstoy et al., 2009). 
Based on the empirical data from those studies, L-DEO developed a sound 
propagation modeling approach that predicts received sound levels as a 
function of distance from a particular airgun array configuration in 
deep water. For this survey, L-DEO modeled Level A and Level B 
harassment zones based on the empirically-derived measurements from the 
Gulf of Mexico calibration survey (Appendix H of NSF-USGS 2011). L-DEO 
used the deep-water radii obtained from model results down to a maximum 
water depth of 2,000 meters (m) (Figures 2 and 3 in Appendix H of NSF-
USGS 2011).
    In 2015, LDEO explored the question of whether the Gulf of Mexico 
calibration data described above adequately informs the model to 
predict exclusion isopleths in other areas by conducting a 
retrospective sound power analysis of one of the lines acquired during 
L-DEO's seismic survey offshore New Jersey in 2014 (Crone, 2015). NMFS 
presented a comparison of the predicted radii (i.e., modeled exclusion 
zones) with radii based on in situ measurements (i.e., the upper bound 
[95th percentile] of the cross-line prediction) in a previous notice of 
issued Authorization for LDEO (see 80 FR 27635, May 14, 2015, Table 1). 
Briefly, the analysis presented in Crone (2015), specific to the survey 
site offshore New Jersey, confirmed that in-situ, site specific 
measurements and estimates of 160 decibel (dB) and 180 dB isopleths 
collected by the hydrophone streamer of the R/V Langseth in shallow 
water were smaller than the modeled (i.e., predicted) zones for two 
seismic surveys conducted offshore New Jersey in shallow water in 2014 
and 2015. In that particular case, Crone's (2015) results showed that 
L-DEO's modeled 180 decibel (dB) and 160 dB zones were approximately 28 
percent and 33 percent larger, respectively, than the in-situ, site-
specific measurements, thus confirming that L-DEO's model was 
conservative in that case.
    The following is a summary of two additional analyses of in-situ 
data that support L-DEO's use of the modeled Level A and Level B 
harassment zones in this particular case. In 2010, L-DEO assessed the 
accuracy of their modeling approach by comparing the sound levels of 
the field measurements acquired in the Gulf of Mexico study to their 
model predictions (Diebold et al., 2010). They reported that the 
observed sound levels from the field measurements fell almost entirely 
below the predicted mitigation radii curve for deep water (i.e., 
greater than 1,000 m; 3,280.8 ft) (Diebold et al., 2010). In 2012, L-
DEO used a similar process to model distances to isopleths 
corresponding to Level A and Level B harassment thresholds for a 
shallow-water seismic survey in the northeast Pacific Ocean offshore 
Washington State. LDEO conducted the shallow-water survey using a 6,600 
in\3\ airgun configuration aboard the R/V Langseth and recorded the 
received sound levels on both the shelf and slope using the Langseth's 
8 km hydrophone streamer. Crone et al. (2014) analyzed those received 
sound levels from the 2012 survey and confirmed that in-situ, site 
specific measurements and estimates of the 160 dB and 180 dB isopleths 
collected by the Langseth's hydrophone streamer in shallow water were 
two to three times smaller than L-DEO's modeling approach had 
predicted. While the results confirmed the role of bathymetry in sound 
propagation, Crone et al. (2014) were also able to confirm that the 
empirical measurements from the Gulf of Mexico calibration survey (the 
same measurements used to inform L-DEO's modeling approach for the 
planned surveys in the northwest Atlantic Ocean) overestimated the size 
of the exclusion and buffer zones for the shallow-water 2012 survey off 
Washington State and were thus precautionary, in that particular case.
    NMFS continues to work with L-DEO to address the issue of 
incorporating site-specific information for future authorizations for 
seismic surveys. However, L-DEO's current modeling approach (supported 
by the three data points discussed previously) represents the best 
available information for NMFS to reach determinations for this IHA. As 
described earlier, the comparisons of L-DEO's model results and the 
field data collected at multiple locations (i.e., the Gulf of Mexico, 
offshore Washington State, and offshore New Jersey) illustrate a degree 
of conservativeness built into L-DEO's model for deep water, which NMFS 
expects to offset some of the limitations of the model to capture the 
variability resulting from site-specific factors. Based upon the best 
available information (i.e., the three data points, two of which are 
peer-reviewed, discussed in this response), NMFS finds that the Level A 
and Level B harassment zone calculations are appropriate for use in 
this particular IHA.
    The use of models for calculating Level A and Level B harassment 
zones and for developing take estimates is not a requirement of the 
MMPA incidental take authorization process. Further, NMFS does not 
prescribe specific model parameters nor a specific model for applicants 
as part of the MMPA incidental take authorization process at this time, 
although we do review methods to ensure they adequately predict take. 
There is a level of variability not only with parameters in the models, 
but also the uncertainty associated with data used in models, and 
therefore, the quality of the model results submitted by applicants. 
NMFS considers this variability when evaluating applications and the 
take estimates and mitigation measures that the model informs. NMFS 
takes into consideration the model used, and its results, in 
determining the potential impacts to marine mammals; however, it is 
just one component of the analysis during the MMPA authorization 
process as NMFS also takes into consideration other factors associated 
with the activity (e.g., geographic location, duration of activities, 
context, sound source intensity, etc.).
    Comment 4: The Commission noted that monitoring and reporting 
requirements adopted need to be sufficient to provide a reasonably 
accurate assessment of the manner of taking and the numbers of animals 
taken incidental to the specified activity. Those assessments should 
account for all animals in the various survey areas, including those 
animals directly on the trackline that are not detected and how well 
animals are detected based on the distance from the observer which is 
achieved by incorporating g(0) and f(0) values. The Commission 
recommended

[[Page 54852]]

that NMFS require L-DEO to use the Commission's method as described in 
the Commission's Addendum to better estimate the numbers of marine 
mammals taken by Level A and B harassment for the incidental harassment 
authorization. The Commission stated that all other NSF-affiliated 
entities and all seismic operators should use this method as well.
    Response: We thank the Commission for their recommendation. NMFS is 
in the process of determining the appropriate method for deriving post-
survey estimates of the total number of animals taken by activities 
such as Scripps' marine geophysical survey.
    Comment 5: The Commission recommended NMFS require SIO to specify 
in the final monitoring report (1) the number of days the survey occurs 
and the array is active and (2) the percentage of time and total time 
the array is active during daylight vs nighttime hours (including dawn 
and dusk).
    Response: NMFS will require SIO to include this information in 
their final monitoring report.
    Comment 6: The Commission recommended that NMFS refrain from using 
the proposed renewal process for SIO's authorization based on the 
complexity of analysis and potential for impacts on marine mammals, and 
the potential burden on reviewers of reviewing key documents and 
developing comments quickly. Additionally, the Commission recommends 
that NMFS use the IHA renewal process sparingly and selectively for 
activities expected to have the lowest levels of impacts to marine 
mammals and that require less complex analysis.
    Response: We appreciate the Commission's input and direct the 
reader to our recent response to the same comment, which can be found 
at 84 FR 31032 (June 28, 2019), pg. 31035-31036. If and when SIO 
requests a Renewal, we will consider the Commission's comment further 
and address the concerns specific to this project. We will consider 
this comment further when and if Scripp's requests a renewal.
    Comment 7: The Commission noted that the proposed surveys are 
scheduled to begin immediately after the public comment period closes 
and expressed concern that NMFS did not have adequate time to consider 
public comments before issuing the IHA. The Commission recommended NMFS 
more thoroughly review applications, draft Federal Register notices, 
and draft proposed authorizations prior to submitting any proposed 
authorizations to the Federal Register, as well as require earlier 
submission of applications and other documentation to ensure sufficient 
time to prepare the proposed authorization and consider comments 
received from the public.
    Response: NMFS thanks the Commission for its concerns regarding the 
IHA process. NMFS thoroughly reviewed the comments received and 
considered all comments in making appropriate revisions to the final 
IHA. NMFS encourages all applicants to submit applications for IHAs 
five to eight months in advance of the intended project start date and 
for rulemakings/LOAs at least nine months, and preferably 15 months, in 
advance of the intended project start date. More generally, NMFS 
publishes Federal Register notices for proposed IHAs as quickly as 
possible once the application is received and aims to allow more time 
on the back end of the comment period, but there are situations where 
the length of processing times are driven by the exigency of an 
applicant's activity start date or by the need to work with applicants 
to ensure we have the necessary information to deem an application 
adequate and complete. Here, NMFS provided the required 30-day notice 
for public comment, and has adequately considered the comments received 
in making the necessary findings for this IHA.
    Comment 8: Falklands Conservation requested clarity on the species 
occurrence determinations in Table 2 in the Federal Register notice of 
proposed IHA (and Table 3 in SIO's IHA application).
    Response: The occurrence as noted is for the survey area at the 
proposed time of the survey and is our professional opinion based on 
all of the available data for the area, as well as the known population 
size in the overall area. This is best professional judgement and is 
mainly meant to serve as a guide to the seismic operator so that they 
can anticipate what species are likely to be encountered during the 
survey and which are not. As noted by Falklands Conservation, data are 
lacking for the area, so it is difficult to make such predictions. The 
take estimates are not based on the occurrence but on the densities, 
which as noted by Falklands Conservation, may not always be ideally 
representative either as they are taken from different areas, but which 
do represent the best available science paired with best professional 
judgement.
    Comment 9: Falklands Conservation noted that the Federal Register 
notice of proposed IHA inaccurately referred to the Falkland Islands as 
a ``known or historic breeding area'' for southern right whales. 
Falklands Conservation also noted that large numbers of southern right 
whales have been recorded off the northeast coast of the Falklands 
seasonally since 2017 and suggested that the occurrence of southern 
right whales might be higher than the ``uncommon'' assessment provided 
in the Federal Register notice. Additionally, Falklands Conservation 
indicated they did not support the assessment of ``uncommon'' for fin 
whales and sei whales.
    Response: We thank Falklands Conservation for their recommended 
correction and suggestions. However, no references were provided to 
support any change in density or abundance estimates for these species, 
and as noted above, these designations have no impact on the take 
estimation. As such, we have determined that this comment does not 
necessitate any changes in our assessment and has no effect on our 
authorized take or findings.
    Comment 10: Falklands Conservation suggested that because the 
planned survey occurs in mostly international waters where few 
abundance or density surveys for marine mammals have been conducted, 
that there are not enough available datasets from comparable areas 
(with regard to the criteria that influence marine mammals such as 
water depth, sea surface temperature, and latitudes) for the take 
requests to be robust.
    Response: As noted by Falklands Conservation, there are limited 
density and abundance surveys available for this region and regions 
with similar environmental qualities. Accordingly, and as described in 
the application and elsewhere in this notice, SIO and NMFS used the 
best available information to determine the appropriate densities for 
estimating take for this project. Falklands Conservation provided no 
references to suggest other densities and abundance information should 
be used in place of those used by SIO and NMFS in the take estimation. 
Therefore, NMFS has not made any changes to the density and abundance 
information presented in the Federal Register notice of proposed IHA.
    Comment 11: Falklands Conservation commented on SIO's discussion of 
the timing of the survey in their IHA application and suggested that 
the survey be scheduled outside of the core periods of baleen whale 
presence.
    Response: SIO's specified activity includes the timing of the 
survey that best represents their goals of acquiring seismic, based on 
the availability of the survey vessel and other logistical issues.

[[Page 54853]]

NMFS has made the necessary findings to issue an IHA for the specified 
activity included in SIO's request, and there is no justification to 
require SIO to completely change their specified activity to occur at a 
different time.
    Comment 12: Falklands Conservation questioned whether the proposed 
mitigation and monitoring measures are sufficient reduce impacts to 
marine mammals. Specifically, Falklands Conservation noted that since 
observers are not required during nighttime operations, passive 
acoustic monitoring (PAM) is the only way to achieve mitigation for 
protected species at night, as well as during adverse sea conditions. 
Falklands Conservation recommended requiring PAM to assist visual 
observation and noted that the Federal Register notice of proposed IHA 
mentioned acoustic monitoring in the summary of the proposed mitigation 
measures.
    Response: The inclusion of acoustic monitoring in the list of 
proposed mitigation measures was inadvertent. NMFS recognizes that PAM 
can be an effective tool in marine mammal detection during nighttime 
operations or when visual observations are otherwise obscured. However, 
given the small Level A and Level B harassment zones and limited 
reduction of impacts anticipated to be gained by the use of PAM, in 
consideration of the cost of implementing PAM systems, we do not 
require PAM for surveys of this nature and size and it is not warranted 
here. As described in the Mitigation section, we have included the 
necessary measures to ensure the least practicable adverse impact on 
the affected species and stocks and their habitat.
    Comment 13: Falklands Conservation requested clarification on the 
adequacy of night vision equipment to be used in the planned survey.
    Response: NMFS does not prescribe any specific equipment be used, 
but examples of night vision equipment include Exelis PVS-7 night 
vision goggles, Night Optics D-300 night vision monocular, and FLIR 
M324XP thermal imaging camera or equivalents.
    Comment 14: Falklands Conservation questioned the rationale for 
requiring a 500-meter (m) exclusion zone for southern right whales, but 
a 100-m exclusion zone for other endangered cetaceans such as blue 
whales and sei whales.
    Response: For small airgun arrays, such as those utilized by SIO 
here, NMFS requires a 100-m exclusion zone for all marine mammal 
species and an extended exclusion zone of 500 m for species or 
circumstances that warrant additional protection. In the northern 
hemisphere, North Atlantic right whales and North Pacific right whales 
are included in the group of species for which we require an extended 
exclusion zone. While southern right whales are not nearly as imperiled 
as their northern hemisphere counterparts, NMFS determined that given 
the similarities between the species, an extended exclusion zone was 
warranted. The 100-m exclusion zone for other species, including listed 
cetaceans, is sufficiently protective for these animals, given the 
sizes of the Level A and Level B harassment zones (up to 6.5 m and 
1,400 m, respectively), as described in the Mitigation section.
    Comment 15: Falklands Conservation suggested that excepting 
specific delphinid species from the shutdown requirement does not 
comply with best practice recommendations which recommend shutting down 
the acoustic source for all species approaching the zone of impact.
    Response: The available information does not suggest that delphinid 
perceived attraction to vessels is likely to have meaningful energetic 
effects to individuals such that the effectiveness of such measures 
outweighs the practicability concerns of requiring the operator to 
shutdown operations when dolphins approach the vessel. NMFS has 
included this delphinid exception in numerous recent authorizations and 
believes it to be an appropriate measure. For additional information, 
please see NMFS discussion of delphinid shutdown exceptions in the 
Federal Register notice of issuance of IHAs to take marine mammals 
incidental to geophysical surveys in the Atlantic Ocean (83 FR 63303; 
December 7, 2018).
    Comment 16: The Falkland Islands Director of Natural Resources 
requested clarification on the meaning of ``take'' in regards to this 
IHA.
    Response: Take is defined under the MMPA as ``to harass, hunt, 
capture, or kill, or attempt to harass, hunt, capture, or kill any 
marine mammal'' (16 U.S.C. 1362). As noted on page 39915 of the Federal 
Register notice of proposed IHA (84 FR 39896; August 12, 2019), 
harassment is the only type of take expected to result from these 
activities. 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). Additional information on the 
definition of take is available on NMFS's website at https://www.fisheries.noaa.gov/national/laws-and-policies/glossary-permits-protected-resources.

Changes From Proposed to Final IHA

    Minor corrections have been made to typographical errors in the 
estimated take table. Additionally, while no take by Level A harassment 
was proposed for any species, some take by Level A harassment has been 
authorized for three species of marine mammals (see Estimated Take 
section).

Description of Marine Mammals in the Area of Specified Activities

    Section 4 of the application summarizes available information 
regarding status and trends, distribution and habitat preferences, and 
behavior and life history, of the potentially affected species. 
Additional information about these species (e.g., physical and 
behavioral descriptions) may be found on NMFS's website (https://www.fisheries.noaa.gov/find-species).
    The populations of marine mammals considered in this document do 
not occur within the U.S. EEZ and are therefore not assigned to stocks 
and are not assessed in NMFS' Stock Assessment Reports (SARs). 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 estimates of abundance presented here are based on a 
variety of proxy sources including International Whaling Commission 
population estimates (IWC 2019), the U.S. Atlantic SARs (Hayes et al., 
2018), and various literature estimates (see IHA application for 
further detail), as this is considered the best available information 
on potential abundance of marine mammals in the area. However, as 
described above, the marine mammals encountered by the planned survey 
are not assigned to stocks. All abundance estimate values presented in 
Table 1 are the most recent available at the time of publication and 
are available in the 2018 U.S. Atlantic SARs (e.g., Hayes et al. 2018) 
available online at: www.fisheries.noaa.gov/national/marine-mammal-
protection/marine-

[[Page 54854]]

mammal-stock-assessments, except where noted otherwise.
    Table 1 lists all species with expected potential for occurrence in 
the Argentine Basin, Southwest Atlantic Ocean, and summarizes 
information related to the population, including regulatory status 
under the MMPA and ESA. For taxonomy, we follow Committee on Taxonomy 
(2018).

 Table 1--Marine Mammal Species Potentially Present in the Project Area Expected To Be Affected by the Specified
                                                   Activities
----------------------------------------------------------------------------------------------------------------
                                                           ESA/ MMPA
                                                            status;                                  Relative
         Common name          Scientific name  Stock \1\   strategic     Abundance        PBR      occurrence in
                                                           (Y/N) \2\                               project area
----------------------------------------------------------------------------------------------------------------
                      Order Cetartiodactyla--Cetacea--Superfamily Mysticeti (baleen whales)
----------------------------------------------------------------------------------------------------------------
Family Balaenidae:
    Southern right whale....  Eubalaena              n/a  E/D;N       12,000,\3\            N.A.  Uncommon.
                               australis.                              3,300 \4\.
Family Cetotheriidae:
    Pygmy right whale.......  Caperea                n/a  ..........  N.A............       N.A.  Rare.
                               marginata.
Family Balaenopteridae
 (rorquals):
    Blue whale..............  Balaenoptera           n/a  E/D;Y       2,300 true,\3\        N.A.  Rare.
                               musculus.                               1,500 pygmy
                                                                       \5\.
    Fin whale...............  Balaenoptera           n/a  E/D;Y       15,000 \5\.....       N.A.  Uncommon.
                               physalus.
    Sei whale...............  Balaenoptera           n/a  E           10,000 \5\.....       N.A.  Uncommon.
                               borealis.
    Common minke whale......  Balaenoptera           n/a  -           515,000 3 6....       N.A.  Common.
                               acutorostrata.
    Antarctic minke whale...  Balaenoptera           n/a  -           515,000 3 6....       N.A.  Common.
                               bonaerensis.
    Humpback whale..........  Megaptera              n/a  -           42,000 \3\.....       N.A.  Rare.
                               novaeangliae.
----------------------------------------------------------------------------------------------------------------
                        Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
----------------------------------------------------------------------------------------------------------------
Family Physeteridae:
    Sperm whale.............  Physeter               n/a  E           12,069 \8\.....       N.A.  Uncommon.
                               macrocephalus.
Family Kogiidae:
    Pygmy sperm whale.......  Kogia breviceps        n/a  -           N.A............       N.A.  Rare.
    Dwarf sperm whale.......  Kogia sima.....        n/a  -           N.A............       N.A.  Rare.
Family Ziphiidae (beaked
 whales):
    Arnoux's beaked whale...  Berardius              n/a  -           599,300 \9\....       N.A.  Uncommon.
                               arnuxii.
    Cuvier's beaked whale...  Ziphius                n/a  -           599,300 \9\....       N.A.  Uncommon.
                               cavirostris.
    Southern bottlenose       Hyperoodon             n/a  -           599,300 \9\....       N.A.  Uncommon.
     whale.                    planifrons.
    Shepherd's beaked whale.  Tasmacetus             n/a  -           N.A............       N.A.  Uncommon.
                               sheperdi.
    Blainville's beaked       Mesoplodon             n/a  -           N.A............       N.A.  Rare.
     whale.                    densirostris.
    Gray's beaked whale.....  Mesoplodon             n/a  -           599,300 \9\....       N.A.  Uncommon.
                               grayi.
    Hector's beaked whale...  Mesoplodon             n/a  -           N.A............       N.A.  Rare.
                               hectori.
    True's beaked whale.....  Mesoplodon             n/a  -           N.A............       N.A.  Rare.
                               mirus.
    Strap-toothed beaked      Mesoplodon             n/a  -           599,300 \9\....       N.A.  Uncommon.
     whale.                    layardii.
    Andrews' beaked whale...  Mesoplodon             n/a  -           N.A............       N.A.  Rare.
                               bowdoini.
    Spade-toothed beaked      Mesoplodon             n/a  -           N.A............       N.A.  Rare.
     whale.                    traversii.
Family Delphinidae:
    Risso's dolphin.........  Grampus griseus        n/a  -           18,250 \10\....       N.A.  Uncommon.
    Rough-toothed dolphin...  Steno                  n/a  -           N.A............       N.A.  Rare.
                               bredanensis.
    Common bottlenose         Tursiops               n/a  -           77,532 \10\....       N.A.  Uncommon.
     dolphin.                  truncatus.
    Pantropical spotted       Stenella               n/a  -           3,333 \10\.....       N.A.  Rare.
     dolphin.                  attenuata.
    Atlantic spotted dolphin  Stenella               n/a  -           44715 \10\.....       N.A.  Rare.
                               frontalis.
    Spinner dolphin.........  Stenella               n/a  -           N.A............       N.A.  Uncommon.
                               longirostris.
    Clymene dolphin.........  Stenella               n/a  -           N.A............       N.A.  Rare.
                               clymene.
    Striped dolphin.........  Stenella               n/a  -           54,807 \10\....       N.A.  Uncommon.
                               coeruleoalba.
    Short-beaked common       Delphinus              n/a  -           70,184 \10\....       N.A.  Uncommon.
     dolphin.                  delphis.
    Fraser's dolphin........  Lagenodelphis          n/a  -           N.A............       N.A.  Rare.
                               hosei.
    Dusky dolphin...........  Lagenorhynchus         n/a  -           7,252 \11\.....       N.A.  Uncommon.
                               obscurus.
    Hourglass dolphin.......  Lagenorhynchus         n/a  -           150,000 \5\....       N.A.  Common.
                               cruciger.
    Peale's dolphin.........  Lagenorhynchus         n/a  -           20,000 \12\....       N.A.  Common.
                               australis.
    Southern right whale      Lissodelphis           n/a  -           N.A............       N.A.  Uncommon.
     dolphin.                  peronii.
    Commerson's dolphin.....  Cephalorhynchus        n/a  -           21,000 \13\....       N.A.  Common.
                               commersonii.
    Killer whale............  Orcinus orca...        n/a  -           25,000 \14\....       N.A.  Uncommon.
    Short-finned pilot whale  Globicephala           n/a  -           200,000 \5\....       N.A.  Rare.
                               macrorhynchus.
    Long-finned pilot whale.  Globicephala           n/a  -           200,000 \5\....       N.A.  Common.
                               melas.
    False killer whale......  Pseudorca              n/a  -           N.A............       N.A.  Rare.
                               crassidens.
Family Phocoenidae
 (porpoises):
    Spectacled porpoise.....  Phocoena               n/a  -           N.A............       N.A.  Uncommon.
                               dioptrica.
----------------------------------------------------------------------------------------------------------------
                                     Order Carnivora--Superfamily Pinnipedia
----------------------------------------------------------------------------------------------------------------
Family Otariidae (eared
 seals and sea lions):
    Antarctic fur seal......  Arctocephalus          n/a  -           4.5-6.2 million       N.A.  Rare.
                               gazella.                                \15\.
    South American fur seal.  Arctocephalus          n/a  -           99,000 \16\....       N.A.  Common.
                               australis.
    Subantarctic fur seal...  Arctocephalus          n/a  -           400,000 \17\...       N.A.  Uncommon.
                               tropicalis.
    South American sea lion.  Otaria                 n/a  -           445,000 \16\...       N.A.  Common.
                               flavescens.
Family Phocidae (earless
 seals):
    Crabeater seal..........  Lobodon                n/a  -           5-10 million          N.A.  Rare.
                               carcinophaga.                           \18\.
    Leopard seal............  Hydrurga               n/a  -           222,000-440,000       N.A.  Rare.
                               leptonyx.                               \19\.
    Southern elephant seal..  Mirounga               n/a  -           750,000 \20\...       N.A.  Uncommon.
                               leonina.
----------------------------------------------------------------------------------------------------------------
N.A. = data not available.
\1\ The populations of marine mammals considered in this document do not occur within the U.S. EEZ and are
  therefore not assigned to stocks.
\2\ 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.
\3\ Southern Hemisphere (IWC 2019).
\4\ Southwest Atlantic (IWC 2019).
\5\ Antarctic (Boyd 2002).
\6\ Dwarf and Antarctic minke whales combined.
\7\ There are 14 distinct population segments (DPSs) of humpback whales recognized under the ESA; the Brazil DPS
  is not listed (NOAA 2017).
\8\ Estimate for the Antarctic, south of 60[deg] S (Whitehead 2002).
\9\ All beaked whales south of the Antarctic Convergence; mostly southern bottlenose whales (Kasamatsu and Joyce
  1995).
\10\ Estimate for the western North Atlantic (Hayes et al., 2018).
\11\ Estimate for Patagonian coast (Dans et al., 1997).
\12\ Estimate for Southern Patagonian waters, Argentina (Dellabianca et al., 2016).
\13\ Total world population (Dawson 2018).

[[Page 54855]]

 
\14\ Minimum estimate for Southern Ocean (Branch and Butterworth 2001).
\15\ South Georgia population (Dawson 2018).
\16\ Total population (C[aacute]rdenas-Alayza et al., 2016a).
\17\ Global population (Hofmeyr and Bester 2018).
\18\ Global population (Bengston and Stewart 2018).
\19\ Global population (Rogers 2018).
\20\ Total world population (Hindell et al., 2016).

    All species that could potentially occur in the planned survey 
areas are included in Table 2. As described below, all 49 species 
temporally and spatially co-occur with the activity to the degree that 
take is reasonably likely to occur, and we have authorized it.
    A detailed description of the species likely to be affected by the 
planned geophysical surveys, including brief introductions to the 
species and relevant stocks as well as available information regarding 
population trends and threats, information regarding local occurrence, 
and marine mammal hearing were provided in the Federal Register notice 
for the proposed IHA (84 FR 39896; August 12, 2019). Since that time, 
we are not aware of any changes in the status of these species and 
stocks; therefore, detailed descriptions are not provided here. Please 
refer to that Federal Register notice for these descriptions. Please 
also refer to NMFS's website (https://www.fisheries.noaa.gov/find-species) for generalized species accounts.

Potential Effects of Specified Activities on Marine Mammals and Their 
Habitat

    The effects from underwater noise from SIO's planned geophysical 
surveys have the potential to result in harassment of marine mammals in 
the vicinity of the action area. The Federal Register notice for the 
proposed IHA (84 FR 39896; August 12, 2019) 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 (84 FR 39896; August 12, 2019) for that 
information. No instances of 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 acoustic sources (i.e., seismic airgun) has the potential to 
result in disruption of behavioral patterns for individual marine 
mammals. There is also some small potential for auditory injury (Level 
A harassment) for high frequency cetaceans (i.e., Kogiidae and 
Lagenorhynchus spp., and spectacled porpoise). Auditory injury is 
unlikely to occur for low frequency cetaceans, mid frequency cetaceans, 
otariid pinnipeds, or phocid pinnipeds given the very small modeled 
zones of injury for those hearing groups (up to 6.5 m). 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.
    Generally speaking, we estimate take by considering: (1) Acoustic 
thresholds above which NMFS believes the best available science 
indicates marine mammals will be behaviorally harassed or incur some 
degree of permanent hearing impairment; (2) the area or volume of water 
that will be ensonified above these levels in a day; (3) the density or 
occurrence of marine mammals within these ensonified areas; and, (4) 
and the number of days of activities. We note that while these basic 
factors can contribute to a basic calculation to provide an initial 
prediction of takes, additional information that can qualitatively 
inform take estimates is also sometimes available (e.g., previous 
monitoring results or average group size). Below, we describe the 
factors considered here in more detail and present the authorized take.

Acoustic Thresholds

    Using the best available science, NMFS has developed acoustic 
thresholds that identify the received level of underwater sound above 
which exposed marine mammals would be reasonably expected to be 
behaviorally harassed (equated to Level B harassment) or to incur PTS 
of some degree (equated to Level A harassment).
    Level B Harassment for non-explosive sources--Though significantly 
driven by received level, the onset of behavioral disturbance from 
anthropogenic noise exposure is also informed to varying degrees by 
other factors related to the source (e.g., frequency, predictability, 
duty cycle), the environment (e.g., bathymetry), and the receiving 
animals (hearing, motivation, experience, demography, behavioral 
context) and can be difficult to predict (Southall et al., 2007, 
Ellison et al., 2012). Based on what the available science indicates, 
and the practical need to use a threshold based on a factor that is 
both predictable and measurable for most activities, NMFS uses a 
generalized acoustic threshold based on received level to estimate the 
onset of behavioral harassment. NMFS predicts that marine mammals are 
likely to be behaviorally harassed in a manner we consider Level B 
harassment when exposed to underwater anthropogenic noise above 
received levels of 120 dB re 1 [mu]Pa (rms) for continuous (e.g., 
vibratory pile-driving, drilling) and above 160 dB re 1 [mu]Pa (rms) 
for non-explosive impulsive (e.g., seismic airguns) or intermittent 
(e.g., scientific sonar) sources.
    SIO's activity includes the use of impulsive seismic sources, and 
therefore the 160 dB re 1 [mu]Pa (rms) is applicable.
    Level A harassment for non-explosive sources--NMFS' Technical 
Guidance for Assessing the Effects of Anthropogenic Sound on Marine 
Mammal Hearing (Version 2.0) (Technical Guidance, 2018) identifies dual 
criteria to assess auditory injury (Level A harassment) to five 
different marine mammal groups (based on hearing sensitivity) as a 
result of exposure to noise from two different types of sources 
(impulsive or non-impulsive). SIO's activity includes the use of 
impulsive seismic sources.
    These thresholds are provided in the table below. The references, 
analysis, and methodology used in the development of the thresholds are 
described in NMFS 2018 Technical Guidance, which may be accessed at 
https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance.

[[Page 54856]]



                     Table 2--Thresholds Identifying the Onset of Permanent Threshold Shift
----------------------------------------------------------------------------------------------------------------
                                                     PTS onset acoustic thresholds * (received level)
             Hearing group              ------------------------------------------------------------------------
                                                  Impulsive                         Non-impulsive
----------------------------------------------------------------------------------------------------------------
Low-Frequency (LF) Cetaceans...........  Cell 1: Lpk,flat: 219 dB;   Cell 2: LE,LF,24h: 199 dB.
                                          LE,LF,24h: 183 dB.
Mid-Frequency (MF) Cetaceans...........  Cell 3: Lpk,flat: 230 dB;   Cell 4: LE,MF,24h: 198 dB.
                                          LE,MF,24h: 185 dB.
High-Frequency (HF) Cetaceans..........  Cell 5: Lpk,flat: 202 dB;   Cell 6: LE,HF,24h: 173 dB.
                                          LE,HF,24h: 155 dB.
Phocid Pinnipeds (PW) (Underwater).....  Cell 7: Lpk,flat: 218 dB;   Cell 8: LE,PW,24h: 201 dB.
                                          LE,PW,24h: 185 dB.
Otariid Pinnipeds (OW) (Underwater)....  Cell 9: Lpk,flat: 232 dB;   Cell 10: LE,OW,24h: 219 dB.
                                          LE,OW,24h: 203 dB.
----------------------------------------------------------------------------------------------------------------
* Dual metric acoustic thresholds for impulsive sounds: Use whichever results in the largest isopleth for
  calculating PTS onset. If a non-impulsive sound has the potential of exceeding the peak sound pressure level
  thresholds associated with impulsive sounds, these thresholds should also be considered.
Note: Peak sound pressure (Lpk) has a reference value of 1 [mu]Pa, and cumulative sound exposure level (LE) has
  a reference value of 1[mu]Pa\2\s. In this Table, thresholds are abbreviated to reflect American National
  Standards Institute standards (ANSI 2013). However, peak sound pressure is defined by ANSI as incorporating
  frequency weighting, which is not the intent for this Technical Guidance. Hence, the subscript ``flat'' is
  being included to indicate peak sound pressure should be flat weighted or unweighted within the generalized
  hearing range. The subscript associated with cumulative sound exposure level thresholds indicates the
  designated marine mammal auditory weighting function (LF, MF, and HF cetaceans, and PW and OW pinnipeds) and
  that the recommended accumulation period is 24 hours. The cumulative sound exposure level thresholds could be
  exceeded in a multitude of ways (i.e., varying exposure levels and durations, duty cycle). When possible, it
  is valuable for action proponents to indicate the conditions under which these acoustic thresholds will be
  exceeded.

Ensonified Area

    Here, we describe operational and environmental parameters of the 
activity that will feed into identifying the area ensonified above the 
acoustic thresholds, which include source levels and transmission loss 
coefficient.
    The planned survey would entail the use of a 2-airgun array with a 
total discharge of 90 in\3\ at a two depth of 2-4 m. Lamont-Doherty 
Earth Observatory (L-DEO) model results are used to determine the 160 
dBrms radius for the 2-airgun array in deep water (>1,000 m) 
down to a maximum water depth of 2,000 m. Received sound levels were 
predicted by L-DEO's model (Diebold et al., 2010) as a function of 
distance from the airguns, for the two 45 in\3\ airguns. This 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 homogenous 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 (~600-1,100 m), and shallow water 
(~50 m) in the Gulf of Mexico in 2007-2008 (Tolstoy et al., 2009; 
Diebold et al., 2010).
    For deep and intermediate water cases, the field measurements 
cannot be used readily to derive the Level A and Level B harassment 
isopleths, as at those sites the calibration hydrophone was located at 
a roughly constant depth of 350-550 m, which may not intersect all the 
SPL isopleths at their widest point from the sea surface down to the 
maximum relevant water depth (~2,000 m) for marine mammals. At short 
ranges, where the direct arrivals dominate and the effects of seafloor 
interactions are minimal, the data at the deep sites are suitable for 
comparison with modeled levels at the depth of the calibration 
hydrophone. At longer ranges, the comparison with the model--
constructed from the maximum SPL through the entire water column at 
varying distances from the airgun array--is the most relevant.
    In deep and intermediate water depths, comparisons at short ranges 
between sound levels for direct arrivals recorded by the calibration 
hydrophone and model results for the same array tow depth are in good 
agreement (see Figures 12 and 14 in Appendix H of NSF-USGS 2011). 
Consequently, isopleths falling within this domain can be predicted 
reliably by the L-DEO model, although they may be imperfectly sampled 
by measurements recorded at a single depth. At greater distances, the 
calibration data show that seafloor-reflected and sub-seafloor-
refracted arrivals dominate, whereas the direct arrivals become weak 
and/or incoherent. Aside from local topography effects, the region 
around the critical distance is where the observed levels rise closest 
to the model curve. However, the observed sound levels are found to 
fall almost entirely below the model curve. Thus, analysis of the Gulf 
of Mexico calibration measurements demonstrates that although simple, 
the L-DEO model is a robust tool for conservatively estimating 
isopleths.
    The planned surveys would acquire data with two 45-in\3\ guns at a 
tow depth of 2-4 m. For deep water (>1000 m), we use the deep-water 
radii obtained from L-DEO model results down to a maximum water depth 
of 2000 m for the airgun array with 2-m and 8-m airgun separation. The 
radii for intermediate water depths (100-1000 m) are derived from the 
deep-water ones by applying a correction factor (multiplication) of 
1.5, such that observed levels at very near offsets fall below the 
corrected mitigation curve (see Figure 16 in Appendix H of NSF-USGS 
2011). The shallow-water radii are obtained by scaling the empirically 
derived measurements from the Gulf of Mexico calibration survey to 
account for the differences in source volume and tow depth between the 
calibration survey (6000 in\3\; 6-m tow depth) and the planned survey 
(90 in\3\; 4-m tow depth); whereas the shallow water in the Gulf of 
Mexico may not exactly replicate the shallow water environment at the 
planned survey sites, it has been shown to serve as a good and very 
conservative proxy (Crone et al., 2014). A simple scaling factor is 
calculated from the ratios of the isopleths determined by the deep-
water L-DEO model, which are essentially a measure of the energy 
radiated by the source array.
    L-DEO's modeling methodology is described in greater detail in 
SIO's IHA application. The estimated distances to the Level B 
harassment isopleths for the two planned airgun configurations in each 
water depth category are shown in Table 3.

[[Page 54857]]



 Table 3--Predicted Radial Distances From R/V Thompson Seismic Source to
         Isopleths Corresponding to Level B Harassment Threshold
------------------------------------------------------------------------
                                                             Predicted
                                                           distances (m)
          Airgun configuration              Water depth      to 160 dB
                                                (m)       received south
                                                               level
------------------------------------------------------------------------
Two 45 in\3\ guns, 2-m separation.......          >1,000         \a\ 539
                                               100-1,000         \b\ 809
                                                    <100       \c\ 1,295
Two 45 in\3\ guns, 8-m separation.......          >1,000         \a\ 578
                                               100-1,000         \b\ 867
                                                    <100       \c\ 1,400
------------------------------------------------------------------------
\a\ Distance based on L-DEO model results.
\b\ Distance based on L-DEO model results with a 1.5 x correction factor
  between deep and intermediate water depths.
\c\ Distance based on empirically derived measurements in the Gulf of
  Mexico with scaling applied to account for differences in tow depth.

    Predicted distances to Level A harassment isopleths, which vary 
based on marine mammal hearing groups, were calculated based on 
modeling performed by L-DEO using the NUCLEUS software program and the 
NMFS User Spreadsheet, described below. The updated acoustic thresholds 
for impulsive sounds (e.g., airguns) contained in the Technical 
Guidance were presented as dual metric acoustic thresholds using both 
SELcum and peak sound pressure metrics (NMFS 2016a). 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 SELcum for the 2-GI airgun array is derived from 
calculating the modified farfield signature. The farfield signature is 
often used as a theoretical representation of the source level. To 
compute the farfield signature, the source level is estimated at a 
large distance (right) 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, it has been recognized that the 
source level from the theoretical farfield signature is never 
physically achieved at the source when the source is an array of 
multiple airguns separated in space (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 interactions of the two 
airguns that occur near the source center and is calculated as a point 
source (single airgun), the modified farfield signature is a more 
appropriate measure of the sound source level for large arrays. For 
this smaller array, the modified farfield changes will be 
correspondingly smaller as well, but we use this method for consistency 
across all array sizes.
    SIO used the same acoustic modeling as Level B harassment with a 
small grid step in both the inline and depth directions to estimate the 
SELcum and peak SPL. The propagation modeling takes into 
account all airgun interactions at short distances from the source 
including interactions between subarrays using the NUCLEUS software to 
estimate the notional signature and the MATLAB software to calculate 
the pressure signal at each mesh point of a grid. For a more complete 
explanation of this modeling approach, please see ``Appendix A: 
Determination of Mitigation Zones'' in SIO's IHA application.

                   Table 4--Modeled Source Levels (dB) for R/V Thompson 90 in\3\ Airgun Arrays
----------------------------------------------------------------------------------------------------------------
                                                    8-kt survey                     5-kt survey
                                                     with 8-m       8-kt survey      with 2-m       5-kt survey
                                                      airgun         with 8-m         airgun         with 2-m
            Functional hearing group                separation:       airgun        separation:       airgun
                                                   Peak SPLflat     separation:    Peak SPLflat     separation:
                                                                      SELcum                          SELcum
----------------------------------------------------------------------------------------------------------------
Low frequency cetaceans (Lpk,flat: 219 dB;                 228.8             207           232.8           206.7
 LE,LF,24h: 183 dB).............................
Mid frequency cetaceans (Lpk,flat: 230 dB;               \1\ N/A           206.7           229.8           206.9
 LE,MF,24h: 185 dB).............................
High frequency cetaceans (Lpk,flat: 202 dB;                  233           207.6           232.9           207.2
 LE,HF,24h: 155 dB).............................
Phocid Pinnipeds (Underwater) (Lpk,flat: 218 dB;             230           206.7           232.8           206.9
 LE,HF,24h: 185 dB).............................
Otariid Pinnipeds (Underwater) (Lpk,flat: 232            \1\ N/A             203           225.6           207.4
 dB; LE,HF,24h: 203 dB).........................
----------------------------------------------------------------------------------------------------------------
\1\ There are no source level values for this airgun configuration for the MF cetaceans and Otariids (maximum
  peak value is 221dB so less than 230 or 232dB). Therefore, we cannot provide any radial distance or modified
  peak far-field values for these two hearing groups.


[[Page 54858]]

    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 Thompson'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 and source velocities and shot intervals provided in SIO's 
IHA application, potential radial distances to auditory injury zones 
were calculated for SELcum thresholds, for both array 
configurations.
    Inputs to the User Spreadsheet in the form of estimated SLs are 
shown in Table 5. User Spreadsheets used by SIO to estimate distances 
to Level A harassment isopleths for the two potential airgun array 
configurations are shown in Tables A-4 and A-5 in Appendix A of SIO's 
IHA application. Outputs from the User Spreadsheet in the form of 
estimated distances to Level A harassment isopleths are shown in Table 
5. As described above, NMFS considers onset of PTS (Level A harassment) 
to have occurred when either one of the dual metrics (SELcum 
or Peak SPLflat) is exceeded (i.e., metric resulting in the 
largest isopleth).

          Table 5--Modeled Radial Distances 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;                34.84               0           34.62               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).........................
----------------------------------------------------------------------------------------------------------------

    Note that because of some of the assumptions included in the 
methods used, isopleths produced may be overestimates to some degree, 
which will ultimately result in some degree of overestimate of Level A 
take. However, these tools offer the best way to predict appropriate 
isopleths when more sophisticated 3D modeling methods are not 
available, and NMFS continues to develop ways to quantitatively refine 
these tools and will qualitatively address the output where 
appropriate. For mobile sources, such as the planned seismic survey, 
the User Spreadsheet predicts the closest distance at which a 
stationary animal would not incur PTS if the sound source traveled by 
the animal in a straight line at a constant speed.

Marine Mammal Occurrence

    In this section we provide the information about the presence, 
density, or group dynamics of marine mammals that informed the take 
calculations.
    For the planned survey area in the southwest Atlantic Ocean, SIO 
determined that the preferred source of density data for marine mammal 
species that might be encountered in the project area north of the 
Falklands was AECOM/NSF (2014). For certain species not included in the 
AECOM database, data from the NOAA Southwest Fisheries Science Center 
(SWFSC) Letter of Authorization (LOA) (2013, in AECOM/NSF 2014) was 
used. Better data on hourglass dolphins, southern bottlenose whales, 
and southern elephant seals were found in White et al. (2002). When 
density estimates were not available in the above named sources, 
densities were estimated using sightings and effort during aerial- and 
vessel-based surveys conducted in and adjacent to the planned project 
area. The three other major sources of animal abundance included White 
et al. (2002), DeTullio et al. (2016) and Garaffo et al. (2011). Data 
sources and density calculations are described in detail in Appendix B 
of SIO's IHA application. For some species, the densities derived from 
past surveys may not be representative of the densities that would be 
encountered during the planned seismic surveys. However, the approach 
used is based on the best available data. Estimated densities used to 
inform take estimates are presented in Table 6.

       Table 6--Marine Mammal Densities in the Planned Survey Area
------------------------------------------------------------------------
                                                             Estimated
                         Species                            density (#/
                                                            km\2\) \a\
------------------------------------------------------------------------
LF Cetaceans:
  Southern right whale..................................         0.00080
  Pygmy right whale.....................................            N.A.
  Blue whale............................................         0.00005
  Fin whale.............................................         0.01820
  Sei whale.............................................         0.00636
  Common (dwarf) minke whale............................         0.07790
  Antarctic minke whale.................................         0.07790
  Humpback whale........................................         0.00066
MF Cetaceans:
  Sperm whale...........................................         0.00207
  Arnoux's beaked whale.................................         0.01138
  Cuvier's beaked whale.................................         0.00055
  Southern bottlenose whale.............................         0.00791
  Shepherd's beaked whale...............................         0.00627
  Blainville's beaked whale.............................         0.00005
  Gray's beaked whale...................................         0.00189
  Hector's beaked whale.................................         0.00021
  True's beaked whale...................................         0.00005
  Strap-toothed beaked whale............................         0.00058
  Andrew's beaked whale.................................         0.00016
  Spade-toothed beaked whale............................         0.00005
  Risso's dolphin.......................................         0.00436
  Routh-toothed dolphin.................................         0.00595
  Common bottlenose dolphin.............................         0.05091
  Pantropical spotted dolphin...........................         0.00377
  Atlantic spotted dolphin..............................         0.22517
  Spinner dolphin.......................................         0.01498
  Clymene dolphin.......................................         0.01162
  Striped dolphin.......................................         0.00719
  Short-beaked common dolphin...........................         0.71717
  Fraser's dolphin......................................            N.A.

[[Page 54859]]

 
  Dusky dolphin.........................................     \b\ 0.12867
  Southern right whale dolphin..........................         0.00616
  Killer whale..........................................         0.01538
  Short-finned pilot whale..............................         0.00209
  Long-finned pilot whale...............................         0.21456
  False killer whale....................................            N.A.
HF Cetaceans:
  Pygmy sperm whale.....................................            N.A.
  Dwarf sperm whale.....................................            N.A.
  Hourglass dolphin.....................................         0.14871
Peale's dolphin.........................................         0.03014
Commerson's dolphin.....................................     \b\ 0.06763
Spectacled porpoise.....................................     \b\ 0.00150
Otariids
  Antarctic fur seal....................................         0.00017
  South American fur seal...............................         0.01642
  Subantarctic fur seal.................................         0.00034
  South American sea lion...............................         0.00249
Phocids:
  Crabeater seal........................................         0.00649
  Leopard seal..........................................         0.00162
  Southern elephant seal................................         0.00155
------------------------------------------------------------------------
N.A. indicates density estimate is not available.
\a\ See Appendix B in SIO's IHA application for density sources.
\b\ Density provided is for shallow water (<100 m depth). A correction
  factor for densities in deeper water was applied (see Appendix B in
  the IHA application).

Take Calculation and Estimation

    Here we describe how the information provided above is brought 
together to produce a quantitative take estimate. In order to estimate 
the number of marine mammals predicted to be exposed to sound levels 
that would result in Level A harassment or Level B harassment, radial 
distances from the airgun array to predicted isopleths corresponding to 
the Level A harassment and Level B harassment thresholds are 
calculated, as described above. Those radial distances are then used to 
calculate the area(s) around the airgun array predicted to be 
ensonified to sound levels that exceed the Level A harassment and Level 
B harassment thresholds. The area estimated to be ensonified in a 
single day of the survey is then calculated (Table 7), based on the 
areas predicted to be ensonified around the array and the estimated 
trackline distance traveled per day. This number is then multiplied by 
the number of survey days. The product is then multiplied by 1.25 to 
account for the additional 25 percent contingency. This results in an 
estimate of the total area (km\2\) expected to be ensonified to the 
Level A and Level B harassment thresholds for each survey type (Table 
7).

                                  Table 7--Areas (km\2\) to be Ensonified to Level A and Level B Harassment Thresholds
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                               Daily                                           Total
                Survey type                           Criteria               Relevant       ensonified     Total survey     25 percent      ensonified
                                                                           isopleth (m)    area (km\2\)        days          increase      area (km\2\)
--------------------------------------------------------------------------------------------------------------------------------------------------------
5-kt survey with 2-m airgun separation....                                           Level B Harassment (160 dB)
                                           -------------------------------------------------------------------------------------------------------------
                                            Deep water..................             539            18.8              16            1.25             376
                                            Intermediate water..........             809          147.32              16            1.25         2,946.4
                                            Shallow water...............           1,295          133.44              16            1.25         2,668.8
                                           -------------------------------------------------------------------------------------------------------------
                                                                                         Level A Harassment
                                           -------------------------------------------------------------------------------------------------------------
                                            LF cetacean.................             6.5            2.89              16            1.25            57.8
                                            MF cetacean.................               1            0.44              16            1.25             8.8
                                            HF cetacean.................            34.6           15.37              16            1.25           307.4
                                            Phocids.....................             5.5            2.44              16            1.25            48.8
                                            Otariids....................             0.5            0.22              16            1.25             4.4
--------------------------------------------------------------------------------------------------------------------------------------------------------
8-kt survey with 8-m airgun separation....                                           Level B Harassment (160 dB)
                                           -------------------------------------------------------------------------------------------------------------
                                            Deep water..................             578           25.64              12            1.25           384.6
                                            Intermediate water..........             867          284.93              12            1.25        4,273.95
                                            Shallow water...............           1,400          220.58              12            1.25          3308.7
                                           -------------------------------------------------------------------------------------------------------------
                                                                                         Level A Harassment
                                           -------------------------------------------------------------------------------------------------------------
                                            LF cetacean.................             3.1            2.22              12            1.25            33.3
                                            MF cetacean.................               0               0              12            1.25               0
                                            HF cetacean.................            34.8           24.93              12            1.25          373.95
                                            Phocids.....................               4            2.86              12            1.25            42.9
                                            Otariids....................               0               0              12            1.25               0
--------------------------------------------------------------------------------------------------------------------------------------------------------

    The total ensonified areas (km\2\) for each criteria presented in 
Table 7 were summed to determine the total ensonified area for all 
survey activities (Table 8).

[[Page 54860]]



         Table 8--Total Ensonified Areas (km\2\) for All Surveys
------------------------------------------------------------------------
                                                        Total ensonified
                       Criteria                         area (km\2\) for
                                                          all surveys
------------------------------------------------------------------------
160 dB Level B (all depths)..........................          13,958.45
160 dB Level B (shallow water).......................             760.60
160 dB Level B (intermediate water)..................           7,220.35
160 dB Level B (deep water)..........................           5,977.50
LF cetacean Level A..................................              91.10
MF cetacean Level A..................................               8.80
HF cetacean Level A..................................             681.35
Phocids Level A......................................              91.70
Otariids Level A.....................................               4.40
------------------------------------------------------------------------

    The marine mammals predicted to occur within these respective 
areas, based on estimated densities (Table 6), are assumed to be 
incidentally taken. While some takes by Level A harassment have been 
estimated, based on the nature of the activity and in consideration of 
the required mitigation measures (see Mitigation section below), Level 
A take of low frequency cetaceans, mid frequency cetaceans, otariid 
pinnipeds, and phocid pinnipeds is not expected to occur and has not 
been authorized. While mitigation is expected to minimize the potential 
for Level A harassment, some Level A take of high-frequency cetaceans 
has been authorized. Estimated exposures for the planned survey are 
shown in Table 9.

                            Table 9--Calculated and Authorized Level A and Level B Exposures, and Percentage of Stock Exposed
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                            Calculated      Calculated      Authorized      Authorized                      Percent of
                         Species                              Level B         Level A         Level B         Level A       Total take      population
--------------------------------------------------------------------------------------------------------------------------------------------------------
LF Cetaceans:
    Southern right whale................................              11               0              11               0              11             0.3
    Pygmy right whale...................................  ..............  ..............           \a\ 2               0               2  ..............
    Blue whale..........................................               1               0           \a\ 3               0               3            <0.1
    Fin whale...........................................             252               2             254               0             254             1.7
    Sei whale...........................................              88               1              89               0              89             0.9
    Common (dwarf) minke whale..........................            1080               7            1087               0            1087             0.2
    Antarctic minke whale...............................            1080               7            1087               0            1087             0.2
    Humpback whale......................................               9               0               9               0               9            <0.1
MF Cetaceans:
    Sperm whale.........................................              29               0              29               0              29             0.2
    Arnoux's beaked whale...............................             159               0             159               0             159            <0.1
    Cuvier's beaked whale...............................               8               0               8               0               8            <0.1
    Southern bottlenose whale...........................             110               0             110               0             110            <0.1
    Shepherd's beaked whale.............................              88               0              88               0              88  ..............
    Blainville's beaked whale...........................               7               0           \a\ 7               0               7  ..............
    Gray's beaked whale.................................              26               0              26               0              26            <0.1
    Hector's beaked whale...............................               3               0               3               0               3  ..............
    True's beaked whale.................................               1               0           \a\ 2               0               2  ..............
    Strap-toothed beaked whale..........................               8               0               8               0               8            <0.1
    Andrew's beaked whale...............................               2               0           \a\ 2               0               2  ..............
    Spade-toothed beaked whale..........................               1               0  ..............               0               2  ..............
    Risso's dolphin.....................................              61               0              61               0              61             0.3
    Rough-toothed dolphin...............................              83               0              83               0              83  ..............
    Common bottlenose dolphin...........................             711               0             711               0             711             0.9
    Pantropical spotted dolphin.........................              53               0              53               0              53             1.6
    Atlantic spotted dolphin............................           3,143               0           3,143               0           3,143             7.0
    Spinner dolphin.....................................             209               0             209               0             209  ..............
    Clymene dolphin.....................................             162               0             162               0             162  ..............
    Striped dolphin.....................................             100               0             100               0             100             0.2
    Short-beaked common dolphin.........................          10,004               6          10,010               0          10,010            14.3
    Fraser's dolphin....................................  ..............  ..............         \a\ 283               0             283  ..............
    Dusky dolphin.......................................           1,034               1           1,035               0           1,035            14.3
    Southern right whale dolphin........................              86               0              86               0              86  ..............
    Killer whale........................................             215               0             215               0             215             0.9
    Short-finned pilot whale............................              29               0          \a\ 41               0              41            <0.1
    Long-finned pilot whale.............................           2,993               2           2,995               0           2,995             1.5
    False killer whale..................................  ..............  ..............           \a\ 5               0               5  ..............
HF Cetaceans:
    Pygmy sperm whale...................................  ..............  ..............           \b\ 2               0               2  ..............
    Dwarf sperm whale...................................  ..............  ..............           \b\ 2               0               2  ..............
    Hourglass dolphin...................................           1,975             101           2,026          \c\ 50           2,076             1.4
    Peale's dolphin.....................................             400              21             411          \c\ 20             421             2.1
    Commerson's dolphin.................................              94              46             117          \c\ 23             140             0.7
    Spectacled porpoise.................................               2               1               3               0               3  ..............
Otariids:
    Antarctic fur seal..................................               2               0               2               0               2            <0.1
    South American fur seal.............................             229               0             229               0             229             0.2
    Subantarctic fur seal...............................               5               0               5               0               5            <0.1
    South American sea lion.............................              35               0              35               0              35            <0.1
Phocids:
    Crabeater seal......................................              90               1              91               0              91            <0.1
    Leopard seal........................................              23               0              23               0              23            <0.1

[[Page 54861]]

 
    Southern elephant seal..............................              22               0              22               0              22            <0.1
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Authorized take increased to mean group size from Bradford (2017) if available. Mean group sizes for pygmy right whale and false killer whale from
  Jefferson et al. (2015) and Mobley et al. (2000), respectively.
\b\ Authorized take increased to maximum group size from Barlow (2016).
\c\ Authorized Level A takes revised from proposed to reflect potential for Level A exposures when mitigation not practicable.

    For some marine mammal species, we authorize a different number of 
incidental takes than the number requested by SIO (see Table 4 in the 
IHA application for requested take numbers). SIO requested Level A 
takes of fin whales, sei whales, common and Antarctic minke whales, 
short-beaked common dolphins, dusky dolphins, long-finned pilot whales, 
and crabeater seals; however, due to very small zones corresponding to 
Level A harassment for low-frequency cetaceans, mid-frequency 
cetaceans, and phocid pinnipeds, 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 have been added to the number of Level B takes.
    While we initially discounted the calculated Level A takes of 
hourglass dolphins, Peale's dolphins, Commerson's dolphins, and 
spectacled porpoises, due to the very small zone corresponding to Level 
A harassment for high-frequency cetaceans, after informal discussions 
with the Commission, we have determined that authorization of some 
Level A take of hourglass dolphins, Peale's dolphins, and Commerson's 
dolphins may be warranted, due to their higher relative densities, and 
have therefore authorized one half of the calculated Level A takes of 
these species (Table 9). The other half of the calculated Level A takes 
of these species have been added to their respective Level B takes. 
While the Level A harassment zone for spectacled porpoises is equal to 
that of hourglass dolphins, Peale's dolphins, and Commerson's dolphins, 
due to their lower density, we have determined that the likelihood of 
Level A take occurring for spectacled porpoises is so low as to be 
discountable. Therefore, we have not authorized Level A take of this 
species, and the calculated Level A takes have been added to the number 
of Level B takes.
    It should be noted that the authorized take numbers shown in Table 
9 are expected to be conservative for several reasons. First, in the 
calculations of estimated take, 25 percent has been added in the form 
of operational survey days to account for the possibility of additional 
seismic operations associated with airgun testing and repeat coverage 
of any areas where initial data quality is sub-standard, and in 
recognition of the uncertainties in the density estimates used to 
estimate take as described above. Additionally, marine mammals would be 
expected to move away from a loud sound source that represents an 
aversive stimulus, such as an airgun array, potentially reducing the 
likelihood of takes by Level A harassment. However, the extent to which 
marine mammals would move away from the sound source is difficult to 
quantify and is, therefore, not accounted for in the take estimates.

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 required mitigation measures 
into their project description based on the above sources.
    To reduce the potential for disturbance from acoustic stimuli 
associated with the activities, SIO is required to implement mitigation 
measures for marine mammals. Mitigation measures that are required to 
be implemented during the planned surveys include (1) Vessel-based 
visual mitigation monitoring; (2) Establishment of a marine mammal 
exclusion zone (EZ) and buffer zone; (3) shutdown procedures; (4) ramp-
up procedures; and (4) vessel strike avoidance measures.

Vessel-Based Visual Mitigation Monitoring

    Visual monitoring requires the use of trained observers (herein 
referred to as visual PSOs) to scan the ocean surface visually for the 
presence of marine mammals. PSO observations must take place during all 
daytime airgun operations and nighttime start ups (if

[[Page 54862]]

applicable) of the airguns. If airguns are operating throughout the 
night, observations must begin 30 minutes prior to sunrise. If airguns 
are operating after sunset, observations must continue until 30 minutes 
following sunset. Following a shutdown for any reason, observations 
must occur for at least 30 minutes prior to the planned start of airgun 
operations. Observations must also occur for 60 minutes after airgun 
operations cease for any reason. Observations must also be made during 
daytime periods when the Thompson 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 must be suspended when 
marine mammals are observed within, or about to enter, the designated 
EZ (as described below).
    During seismic operations, three visual PSOs must be based aboard 
the Thompson. PSOs must be appointed by SIO with NMFS approval. One 
dedicated PSO must monitor the EZ during all daytime seismic 
operations. PSO(s) must be on duty in shifts of duration no longer than 
4 hours. Other vessel crew must 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 must 
be given additional instruction in detecting marine mammals and 
implementing mitigation requirements.
    The Thompson is a suitable platform from which PSOs would watch for 
marine mammals. Standard equipment for marine mammal observers would be 
7 x 50 reticule binoculars and optical range finders. At night, night-
vision equipment would be available. The observers must 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 must 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 must 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.

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 must establish a minimum EZ with a 100 m radius for the airgun 
array. The 100-m EZ must 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 must 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 5) 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 is also 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 5). 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 required 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 must 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) must 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.
    An extended EZ of 500 m must be enforced for all beaked whales, 
Kogia species, and Southern right whales. SIO must also enforce a 500-m 
EZ for aggregations of six or more large whales (i.e., sperm whale or 
any baleen whale) that does not appear to be traveling (e.g., feeding, 
socializing, etc.) or a large whale with a calf (calf defined as an 
animal less than two-thirds the body size of an adult observed to be in 
close association with an adult).

Shutdown Procedures

    If a marine mammal is detected outside the EZ but is likely to 
enter the EZ, the airguns must 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 must be shut down immediately.
    Following a shutdown, airgun activity must not resume until the 
marine mammal has cleared the 100-m EZ. The animal is 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;
     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 sperm, 
beaked whales, pilot whales, and Risso's dolphins.
    This shutdown requirement must 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 applies solely to specific genera of small dolphins--
Delphinus, Lagenodelphis, Lagenorhynchus, Lissodelphis, Stenella, 
Steno, and Tursiops--and only applies 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

[[Page 54863]]

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, shutdown must 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 above, auditory injury is extremely unlikely 
to occur for mid-frequency cetaceans (e.g., delphinids), as this group 
is relatively insensitive to sound produced at the predominant 
frequencies in an airgun pulse while also having a relatively high 
threshold for the onset of auditory injury (i.e., permanent threshold 
shift).
    A large body of anecdotal evidence indicates that small delphinoids 
commonly approach vessels and/or towed arrays during active sound 
production for purposes of bow riding, with no apparent effect observed 
in those delphinoids (e.g., Barkaszi et al., 2012). The potential for 
increased shutdowns resulting from such a measure would require the 
Thompson to revisit the missed track line to reacquire data, resulting 
in an overall increase in the total sound energy input to the marine 
environment and an increase in the total duration over which the survey 
is active in a given area. Although other mid-frequency hearing 
specialists (e.g., large delphinoids) are no more likely to incur 
auditory injury than are small delphinoids, they are much less likely 
to approach vessels. Therefore, retaining a power-down/shutdown 
requirement for large delphinoids would not have similar impacts in 
terms of either practicability for the applicant or corollary increase 
in sound energy output and time on the water. We do anticipate some 
benefit for a 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 is also required upon observation 
of 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 Level B 
harassment zones.

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 is required after the array is 
shut down for any reason for longer than 15 minutes. Ramp-up must begin 
with the activation of one 45 in\3\ airgun, with the second 45 in\3\ 
airgun activated after 5 minutes.
    Two PSOs are required to monitor during ramp-up. During ramp up, 
the PSOs must monitor the EZ, and if marine mammals were observed 
within the EZ or buffer zone, a shutdown must 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 must not be initiated until all marine mammals have cleared the 
EZ, during the day or night. Criteria for clearing the EZ is 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 must not be 
initiated until all marine mammals cleared the EZ. Criteria for 
clearing the EZ would 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 must 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 must 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 would create an imminent and serious 
threat to a person or vessel or to the extent that a vessel is 
restricted in its ability to maneuver and, because of the restriction, 
cannot comply.
    The required measures include the following: Vessel operator and 
crew must 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 must monitor a vessel 
strike avoidance zone around the vessel according to the parameters 
stated below. Visual observers monitoring the vessel strike avoidance 
zone may be either third-party observers or crew members, but crew 
members responsible for these duties must be provided sufficient 
training to distinguish marine mammals from other phenomena. Vessel 
strike avoidance measures must be followed during surveys and while in 
transit.
    The vessel must 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 must reduce speed and 
shift the engine to neutral, and must 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 
must not engage engines until the whale(s) has moved out of the 
vessel's path and beyond 100 m. The vessel must maintain a minimum 
separation distance of 50 m from all other marine mammals (with the 
exception of delphinids of the genera Delphinus, Lagenodelphis, 
Lagenorhynchus, Lissodelphis, Stenella, Steno, and Tursiops that 
approach the vessel, as described above). If an animal is encountered 
during transit, the vessel must attempt to remain parallel to the

[[Page 54864]]

animal's course, avoiding excessive speed or abrupt changes in course. 
Vessel speeds must be reduced to 10 kt or less when mother/calf pairs, 
pods, or large assemblages of cetaceans are observed near the vessel.
    Based on our evaluation of the required measures, NMFS has 
determined that the required mitigation measures provide the means 
effecting the least practicable impact on the affected species or 
stocks and their habitat, paying particular attention to rookeries, 
mating grounds, and areas of similar significance.

Monitoring and Reporting

    In order to issue an IHA for an activity, Section 101(a)(5)(D) of 
the MMPA states that NMFS must set forth requirements pertaining to the 
monitoring and reporting of such taking. The MMPA implementing 
regulations at 50 CFR 216.104 (a)(13) indicate that requests for 
authorizations must include the suggested means of accomplishing the 
necessary monitoring and reporting that will result in increased 
knowledge of the species and of the level of taking or impacts on 
populations of marine mammals that are expected to be present in the 
planned action area. Effective reporting is critical both to compliance 
as well as ensuring that the most value is obtained from the required 
monitoring.
    Monitoring and reporting requirements prescribed by NMFS should 
contribute to improved understanding of one or more of the following:
     Occurrence of marine mammal species or stocks in the area 
in which take is anticipated (e.g., presence, abundance, distribution, 
density).
     Nature, scope, or context of likely marine mammal exposure 
to potential stressors/impacts (individual or cumulative, acute or 
chronic), through better understanding of: (1) Action or environment 
(e.g., source characterization, propagation, ambient noise); (2) 
affected species (e.g., life history, dive patterns); (3) co-occurrence 
of marine mammal species with the action; or (4) biological or 
behavioral context of exposure (e.g., age, calving or feeding areas).
     Individual marine mammal responses (behavioral or 
physiological) to acoustic stressors (acute, chronic, or cumulative), 
other stressors, or cumulative impacts from multiple stressors.
     How anticipated responses to stressors impact either: (1) 
Long-term fitness and survival of individual marine mammals; or (2) 
populations, species, or stocks.
     Effects on marine mammal habitat (e.g., marine mammal prey 
species, acoustic habitat, or other important physical components of 
marine mammal habitat).
     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 must take place during daytime 
airgun operations and nighttime start-ups (if applicable) of the 
airguns. During seismic operations, three visual PSOs must be based 
aboard the Thompson. PSOs must be appointed by SIO with NMFS approval. 
The PSOs must have successfully completed relevant training, including 
completion of all required coursework and passing a written and/or oral 
examination developed for the training program, and must have 
successfully attained a bachelor's degree from an accredited college or 
university with a major in one of the natural sciences and a minimum of 
30 semester hours or equivalent in the biological sciences and at least 
one undergraduate course in math or statistics. The educational 
requirements may be waived if the PSO has acquired the relevant skills 
through alternate training, including (1) secondary education and/or 
experience comparable to PSO duties; (2) previous work experience 
conducting academic, commercial, or government-sponsored marine mammal 
surveys; or (3) previous work experience as a PSO; the PSO should 
demonstrate good standing and consistently good performance of PSO 
duties.
    During the majority of seismic operations, one PSO is required to 
monitor for marine mammals around the seismic vessel. PSOs must be on 
duty in shifts of duration no longer than 4 hours. Other crew must also 
be instructed to assist in detecting marine mammals and in implementing 
mitigation requirements (if practical). During daytime, PSOs must scan 
the area around the vessel systematically with reticle binoculars 
(e.g., 7x50 Fujinon) and with the naked eye. At night, PSOs must be 
equipped with night-vision equipment.
    PSOs must 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 must be used to estimate 
numbers of animals potentially `taken' by harassment (as defined in the 
MMPA). They must 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 must 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 must be recorded in a standardized 
format. Data must be entered into an electronic database. The accuracy 
of the data entry must be verified by computerized data validity checks 
as the data are entered and by subsequent manual checking of the 
database. These procedures allow initial summaries of data to be 
prepared during and shortly after the field program and 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 must 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 must 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 draft report must be submitted to NMFS within 90 days after the 
end of

[[Page 54865]]

the survey. The report must describe the operations that were conducted 
and sightings of marine mammals near the operations. The report must 
provide full documentation of methods, results, and interpretation 
pertaining to all monitoring and would summarize the dates and 
locations of seismic operations, including percentage of time and total 
time the array is active during daylight vs nighttime hours (including 
dawn and dusk), and all marine mammal sightings (dates, times, 
locations, activities, associated seismic survey activities). The 
report must also include estimates of the number and nature of 
exposures that occurred above the harassment threshold based on PSO 
observations.
    The draft report must also include geo-referenced time-stamped 
vessel tracklines for all time periods during which airguns were 
operating. Tracklines must include points recording any change in 
airgun status (e.g., when the airguns began operating, when they were 
turned off, or when they changed from full array to single gun or vice 
versa). GIS files must be provided in ESRI shapefile format and include 
the UTC date and time, latitude in decimal degrees, and longitude in 
decimal degrees. All coordinates must be referenced to the WGS84 
geographic coordinate system. In addition to the report, all raw 
observational data must be made available to NMFS. The draft report 
must be accompanied by a certification from the lead PSO as to the 
accuracy of the report, and the lead PSO may submit directly NMFS a 
statement concerning implementation and effectiveness of the required 
mitigation and monitoring. A final report must be submitted within 30 
days following resolution of any comments on the draft report.

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 1, given that NMFS expects the anticipated effects of the 
planned seismic survey to be similar in nature. Where there are 
meaningful differences between species or stocks, or groups of species, 
in anticipated individual responses to activities, impact of expected 
take on the population due to differences in population status, or 
impacts on habitat, NMFS has identified species-specific factors to 
inform the analysis.
    NMFS does not anticipate that serious injury or mortality would 
occur as a result of SIO's planned seismic survey, even in the absence 
of required 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 authorized a limited number of instances of Level A harassment 
(Table 9) for three species. However, we believe that any PTS incurred 
in marine mammals as a result of the planned activity would be in the 
form of only a small degree of PTS (not total deafness), because of the 
constant movement of both the Thompson 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). A small 
degree of PTS that would not be likely to affect the fitness of any 
individuals, much less the population. 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 
Thompson'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 in the 
Federal Register Notice for the Proposed IHA (see Potential Effects of 
the Specified Activity on Marine Mammals and their Habitat). Marine 
mammal habitat may be impacted by elevated sound levels, but these 
impacts would be temporary. Prey species are mobile and are broadly 
distributed throughout the project 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 planned project 
area.
    As described above, marine mammals in the survey area are not 
assigned to NMFS stocks. For purposes of the small numbers analysis we 
rely on 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 
15 percent each for all marine mammal populations where abundance 
estimates exist). Additionally, the acoustic ``footprint'' of the 
planned 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 planned 
survey area. The seismic array would be active 24 hours per day 
throughout the duration of the planned survey. However, the very brief 
overall duration

[[Page 54866]]

of the planned survey (28 days) would further limit potential impacts 
that may occur as a result of the planned activity.
    The required mitigation measures are expected to reduce the number 
and/or severity of takes by allowing for detection of marine mammals in 
the vicinity of the vessel by visual and acoustic observers, and by 
minimizing the severity of any potential exposures via shutdowns of the 
airgun array. Based on previous monitoring reports for substantially 
similar activities that have been previously authorized by NMFS, we 
expect that the required mitigation will be effective in preventing at 
least some extent of potential PTS in marine mammals that may otherwise 
occur in the absence of the required mitigation.
    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, sperm, and southern right 
whales. We are proposing to authorize very small numbers of takes for 
these species (Table 9), relative to their population sizes (again, for 
species where population abundance estimates exist), 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 have authorized take, none are considered ``depleted'' or 
``strategic'' by NMFS under the MMPA.
    NMFS concludes that exposures to marine mammal species due to SIO's 
planned seismic survey would result in only short-term (temporary and 
short in duration) behavioral disruption of 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 authorized take to impact annual rates of 
recruitment or survival.
    In summary and as described above, the following factors primarily 
support our determination that the impacts resulting from this activity 
are not expected to adversely affect the species or stock through 
effects on annual rates of recruitment or survival:
     No mortality is anticipated or authorized;
     The anticipated impacts of the planned activity on marine 
mammals would primarily be temporary behavioral changes due to 
avoidance of the area around the survey vessel. The relatively short 
duration of the planned survey (28 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 9). Instances of PTS that are 
incurred in marine mammals would be of a low level, due to constant 
movement of the vessel and of the marine mammals in the area, and the 
nature of the survey design (not concentrated in areas of high marine 
mammal concentration);
     The availability of alternate areas of similar habitat 
value for marine mammals to temporarily vacate the survey area during 
the planned survey to avoid exposure to sounds from the activity;
     The planned 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 planned 
survey would be temporary and spatially limited; and
     The required mitigation measures, including visual 
monitoring and shutdowns, are expected to minimize potential impacts to 
marine mammals.
    Based on the analysis contained herein of the likely effects of the 
specified activity on marine mammals and their habitat, and taking into 
consideration the implementation of the required monitoring and 
mitigation measures, NMFS finds that the total marine mammal take from 
the planned activity will have a negligible impact on all affected 
marine mammal species or stocks.

Small Numbers

    As noted above, only small numbers of incidental take may be 
authorized under Sections 101(a)(5)(A) and (D) of the MMPA for 
specified activities other than military readiness activities. The MMPA 
does not define small numbers and so, in practice, where estimated 
numbers are available, NMFS compares the number of individuals taken to 
the most appropriate estimation of abundance of the relevant species or 
stock in our determination of whether an authorization is limited to 
small numbers of marine mammals. Additionally, other qualitative 
factors may be considered in the analysis, such as the temporal or 
spatial scale of the activities.
    The numbers of marine mammals that we authorize to be taken would 
be considered small relative to the relevant populations (less than 15 
percent for all species) for the species for which abundance estimates 
are available. No known current worldwide or regional population 
estimates are available for 16 species under NMFS jurisdiction that 
could be incidentally taken as a result of the planned survey: The 
pygmy right whale, pygmy sperm whale, dwarf sperm whale, Shepherd's 
beaked whale, Blainville's beaked whale, Hector's beaked whale, True's 
beaked whale, Andrew's beaked whale, spade-toothed beaked whale, rough-
toothed dolphin, spinner dolphin, Clymene dolphin, Fraser's dolphin, 
southern right whale dolphin, false killer whale, and spectacled 
porpoise.
    NMFS has reviewed the geographic distributions and habitat 
preferences of these species in determining whether the numbers of 
takes authorized herein are likely to represent small numbers. Pygmy 
right whales have a circumglobal distribution and occur throughout 
coastal and oceanic waters in the Southern Hemisphere (between 30 to 
55[deg] S) (Jefferson et al., 2008). Pygmy and dwarf sperm whales occur 
in deep waters on the outer continental shelf and slope in tropical to 
temperate waters of the Atlantic, Indian, and Pacific Oceans. Based on 
stranding records and the known habitat preferences of beaked whales in 
general, Shepherd's beaked whales are assumed to have a circumpolar 
distribution in deep, cold temperate waters of the Southern Ocean 
(Pitman et al., 2006). Blainville's beaked whale is the most widely 
distributed beaked Mesoplodon species with sightings and stranding 
records throughout the North and South Atlantic Ocean (MacLeod et al., 
2006). Hector's beaked whales are found in cold temperate waters 
throughout the southern hemisphere between 35[deg] S and 55[deg] S 
(Zerbini and Secchi 2001). True's beaked whales occur in the Southern 
hemisphere from the western Atlantic Ocean to the Indian Ocean to the 
waters of southern Australia and possibly New Zealand (Jefferson et 
al., 2008). Andrew's beaked whales have a circumpolar distribution 
north of the Antarctic Convergence to 32[deg] S (MacLeod et al., 2006). 
Stranding records of spade-toothed beaked whales suggest a Southern 
hemisphere distribution in temperate waters between 33[deg] and 44[deg] 
S in the South Pacific, with potential occurrence in the southern 
Atlantic Ocean (MacLeod et al., 2006). Rough-toothed dolphins occur in 
tropical and warm temperate

[[Page 54867]]

seas around the world, preferring deep offshore waters (Lodi 1992). 
Spinner dolphins are found in tropical, subtropical, and, less 
frequently, warm temperate waters throughout the world (Secchi and 
Siciliano 1995). The Clymene dolphin is found in tropical and warm 
temperate waters of both the North and South Atlantic Oceans (Fertl et 
al., 2003). Fraser's dolphins are distributed in tropical oceanic 
waters worldwide, between 30[deg] N and 30[deg] S (Moreno et al., 
2003). Southern right whale dolphins have a circumpolar distribution 
and generally occur in deep temperate to sub-Antarctic waters in the 
Southern hemisphere (between 30 to 65[deg] S) (Jefferson et al.,2008). 
Short-finned pilot whales are found in warm temperate to tropical 
waters throughout the world, generally in deep offshore areas (Olson 
and Reilly, 2002). Spectacled porpoises occur in oceanic cool temperate 
to Antarctic waters and are circumpolar in high latitude Southern 
hemisphere distribution (Natalie et al., 2018).
    Based on the broad spatial distributions and habitat preferences of 
these species relative to the areas where SIO's planned survey will 
occur, NMFS concludes that the authorized take of these species likely 
represent small numbers relative to the affected species' overall 
population sizes, though we are unable to quantify the take numbers as 
a percentage of population.
    Based on the analysis contained herein of the planned activity 
(including the required mitigation and monitoring measures) and the 
anticipated take of marine mammals, NMFS finds that small numbers of 
marine mammals will be taken relative to the population size of the 
affected species or stocks.

Unmitigable Adverse Impact Analysis and Determination

    There are no relevant subsistence uses of the affected marine 
mammal stocks or species implicated by this action. Therefore, NMFS has 
determined that the total taking of affected species or stocks would 
not have an unmitigable adverse impact on the availability of such 
species or stocks for taking for subsistence purposes.

National Environmental Policy Act

    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 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.

Endangered Species Act (ESA)

    Section 7(a)(2) of the Endangered Species Act of 1973 (ESA: 16 
U.S.C. 1531 et seq.) requires that each Federal agency insure that any 
action it authorizes, funds, or carries out is not likely to jeopardize 
the continued existence of any endangered or threatened species or 
result in the destruction or adverse modification of designated 
critical habitat. To ensure ESA compliance for the issuance of IHAs, 
NMFS consults internally, in this case with the ESA Interagency 
Cooperation Division, whenever we propose to authorize take for 
endangered or threatened species.
    The NMFS Office of Protected Resources Interagency Cooperation 
Division issued a Biological Opinion on September 11, 2019, under 
section 7 of the ESA, on the issuance of an IHA to SIO under section 
101(a)(5)(D) of the MMPA by the NMFS Permits and Conservation Division. 
The Biological Opinion concluded that the proposed action is not likely 
to jeopardize the continued existence of fin whale, sei whale, blue 
whale, sperm whale, and southern right whale, and is not likely to 
destroy or modify critical habitat of listed species because no 
critical habitat exists for these species in the action area.

Authorization

    NMFS has issued an IHA to SIO for the potential harassment of small 
numbers of 49 marine mammal species incidental to a marine geophysical 
survey in the southwest Atlantic Ocean, provided the previously 
mentioned mitigation, monitoring, and reporting are incorporated.

    Dated: October 7, 2019.
Donna S. Wieting,
Director, Office of Protected Resources, National Marine Fisheries 
Service.
[FR Doc. 2019-22285 Filed 10-10-19; 8:45 am]
BILLING CODE 3510-22-P