Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to a Marine Geophysical Survey in the Northwest Atlantic Ocean, 39692-39709 [2018-17170]

Agencies

• DEPARTMENT OF COMMERCE
• National Oceanic and Atmospheric Administration

[Federal Register Volume 83, Number 155 (Friday, August 10, 2018)]
[Notices]
[Pages 39692-39709]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2018-17170]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

RIN 0648-XG170


Takes of Marine Mammals Incidental to Specified Activities; 
Taking Marine Mammals Incidental to a Marine Geophysical Survey in the 
Northwest Atlantic Ocean

AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and 
Atmospheric Administration (NOAA), Commerce.

ACTION: Notice; issuance of an incidental harassment authorization.

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SUMMARY: In accordance with the regulations implementing the Marine 
Mammal Protection Act (MMPA) as amended, notification is hereby given 
that NMFS has issued an incidental harassment authorization (IHA) to 
USGS to incidentally harass, by Level B harassment only, marine mammals 
during geophysical survey activities associated with a the USGS's Mid-
Atlantic Resource Imaging Experiment (MATRIX) survey project in the 
Northwest Atlantic Ocean.

DATES: This Authorization is effective from August 1, 2018 to July 31, 
2019.

FOR FURTHER INFORMATION CONTACT: Jonathan Molineaux, 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/national/marine-mammal-protection/incidental-take-authorizations-research-and-other-activities. In case of problems 
accessing these documents, please call the contact listed above.

SUPPLEMENTARY INFORMATION:

Background

    Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 et seq.) 
direct the Secretary of Commerce (as delegated to NMFS) to allow, upon 
request, the incidental, but not intentional, taking of small numbers 
of marine mammals by U.S. citizens who engage in a specified activity 
(other than commercial fishing) within a specified geographical region 
if certain findings are made and either regulations are issued or, if 
the taking is limited to harassment, a notice of a proposed 
authorization is provided to the public for review.
    An authorization for incidental takings shall be granted if NMFS 
finds that the taking will have a negligible impact on the species or 
stock(s), will not have an unmitigable adverse impact on the 
availability of the species or stock(s) for subsistence uses (where 
relevant), and if the permissible methods of taking and requirements 
pertaining to the mitigation, monitoring and reporting of such takings 
are set forth.
    NMFS has defined ``negligible impact'' in 50 CFR 216.103 as an 
impact resulting from the specified activity that cannot be reasonably 
expected to, and is not reasonably likely to, adversely affect the 
species or stock through effects on annual rates of recruitment or 
survival.''
    The MMPA states that the term ``take'' means to harass, hunt, 
capture, kill or attempt to harass, hunt, capture, or kill any marine 
mammal.
    Except with respect to certain activities not pertinent here, the 
MMPA defines ``harassment'' as: Any act of pursuit, torment, or 
annoyance which (i) has the potential to injure a marine mammal or 
marine mammal stock in the wild (Level A harassment); or (ii) has the 
potential to disturb a marine mammal or marine mammal stock in the wild 
by causing disruption of behavioral patterns, including, but not 
limited to, migration, breathing, nursing, breeding, feeding, or 
sheltering (Level B harassment).

Summary of Request

    On March 20, 2018, NMFS received a request from USGS for an IHA to 
take marine mammals incidental to a marine geophysical survey in the 
northwest Atlantic Ocean. On April 11, 2018, we deemed USGS's 
application for authorization to be adequate and complete. USGS 
requests to take small numbers of 29 species of marine mammals by Level 
B harassment only during the survey. Neither USGS nor NMFS expects 
serious injury or mortality to result from this activity; and, 
therefore, an IHA is appropriate.

Description of Activity

    The USGS will conduct a seismic survey aboard the R/V Hugh R. 
Sharp, a University National Oceanographic Laboratory (UNOLS) Federal 
fleet vessel that is owned and operated by the University of Delaware, 
during a cruise up to 22 days long on the northern U.S. Atlantic margin 
in August 2018. The seismic survey will take place in water depths 
ranging from ~100 meters (m) to 3,500 m, entirely within the U.S.

[[Page 39693]]

Exclusive Economic Zone (EEZ), and acquire ~6 dip lines (roughly 
perpendicular to the orientation of the shelf-break) and ~3 strike 
lines (roughly parallel to the shelf-break) between about 35 nautical 
miles (nmi) south of Hudson Canyon on the north and Cape Hatteras on 
the south. In addition, multichannel seismic (MCS) data will be 
acquired along some linking/transit/interseismic lines between the main 
survey lines. Total data acquisition could be up to ~2,400 kilometers 
(km) of trackline.
    The purpose of the MATRIX survey is to collect data to constrain 
the lateral and vertical distribution of gas hydrates and shallow 
natural gas in marine sediments relative to seafloor gas seeps, slope 
failures, and geological and erosional features.
    The seismic survey's airgun operations are scheduled to occur for 
up to 19 days during a cruise that may be as long as 22 days, departing 
port on August 8, 2018. Some minor deviation from these dates is 
possible, depending on logistics and weather.
    The survey will involve only one source vessel, the R/V Hugh R. 
Sharp. The source vessel will deploy two to four low-energy Generator-
Injector (GI) airguns (each with a discharge volume of 105 cubic inches 
(in\3\)) as an energy source. The GI guns could sometimes be fired in a 
mode that gives them a discharge volume of 210 in\3\ each, but only at 
water depths greater than 1000 m (See description of Optimal Survey 
below for more details).
    The Optimal Survey (GG mode) (See Table 1) for the Proposed Action 
would acquire the portion of the solid lines in Figure 1 of the IHA 
application at water depths greater than 1000 m using the GI-guns in 
``GG'' mode. In this mode, the four GI guns would produce a total of 
840 in\3\ of air and sonobuoys would be deployed to passively record 
data at long distances. When shooting to sonobuoys while in GG mode, 
the GI guns will be operated with both chambers releasing air 
simultaneously (i.e., ``generator-generator'' or ``GG'' mode). The rest 
of the survey, including the portion shallower than 1000 m water depth 
on the uppermost slope and the interseismic linking lines (dashed lines 
in Figure 1), would be acquired with four GI guns operated in normal 
mode (also called GI mode), producing a total of 420 in\3\ of air.
    The Base Survey (GI mode) (See Table 1) assumes that all of the 
solid lines in Figure 1, as well as all of the interseismic connecting 
lines, would be acquired using four GI guns operating in normal mode 
(GI mode), producing a total air volume of 420 in\3\. Only a maximum of 
half of the interseismic linking lines (dashed lines in Figure 1) would 
be acquired. These lines are longer and geometrically more complex at 
the deepwater side than near the shelf-break.

             Table 1--General Characteristics of Exemplary Survey Scenarios for the Proposed Action
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                                     GI mode (4 x 105 in\3\)                    GG mode (4 x 210 in\3\)
                           -------------------------------------------------------------------------------------
                                                         Track line                                 Track line
                               Depth and line type      distance (km)     Depth and line type        distance
----------------------------------------------------------------------------------------------------------------
Optimal Survey............  100-1,000 m water depth              ~750  Greater than 1,000 m on            ~1,600
                             on exemplary lines and                     exemplary lines.
                             50% of interseismic,
                             linking lines.
Base Survey...............  Exemplary lines plus 50%            2,350  .........................  ..............
                             of interseismic, linking
                             lines.
----------------------------------------------------------------------------------------------------------------

    During the cruise, the USGS would continuously use an echosounder 
(EK60/EK80) with 38 kHz transducer at water depths less than ~1,800 m 
to locate water column anomalies associated with seafloor seeps 
emitting gas bubbles. The 38 kHz transducer would be mounted in the R/V 
Sharp's retractable keel and would typically ping 0.5 to 2 Hz with 
pings of 0.256 to 1.024 millisecond (m/s) duration. The returned 
signals would be detected on an EK60 or EK80 (broadband) transceiver. 
Based on past USGS experience with this instrument, it is unlikely to 
acquire useful data at water depths greater than 1,800 m, although it 
could be used in passive mode at these depths to record broadband 
ambient signals in the water column.
    A more detailed description of USGS's MATRIX survey is provided in 
the Federal Register notice for the proposed IHA (83 FR 25268; May 31, 
2018). Since that time, no changes have been made to the planned survey 
activities. Therefore, a detailed description is not provided here. 
Please refer to that Federal Register notice for the description of the 
specific activity.

Comments and Responses

    NMFS published a notice of proposed IHA in the Federal Register on 
May 31, 2018 (83 FR 25268). During the 30-day public comment period, 
NMFS received a comment letter from the Marine Mammal Commission 
(Commission). NMFS has posted the comments online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-research-and-other-activities. The following is a 
summary of the public comments and NMFS' responses.
    Comment 1: After review of the Federal Register notice of the 
proposed IHA (83 FR 25268; May 31, 2018) and IHA application for the 
USGS MATRIX survey, the Commission inferred that the modeling used by 
USGS (Lamont-Doherty Earth Observatory (LDEO)'s Nucleus Model) to 
predict Level A and Level B harassment zones applied radial distances 
(i.e., slant ranges) and radii indiscriminately. The Commission states 
that radial distances were used for metrics based on SELcum 
and SPL root-mean-square (SPLrms), and radii were used for 
metrics based on SPLpeak, which would yield smaller zones. 
As a result, the Commission recommends that NMFS require USGS to 
specify why LDEO's Nucleus Model is using radial distances for sound 
exposure level (SELcum) and sound pressure level 
(SPLrms) metrics and radii for peak sound pressure 
(SPLpeak) metrics.
    Response: NMFS appreciates the Commission's request for USGS to 
explain the specific methodology LDEO's Nucleus Model uses to determine 
harassment zones. After consulting with LDEO, USGS has clarified that 
two different methods for estimating distance are not being used. In 
order to calculate harassment zones, LDEO uses the maximum radial 
distance at depth which it vertically projects from that radial 
distance back to the surface. This provides a horizontal radius from 
the source.
    Comment 2: The Commission recommends NMFS provide

[[Page 39694]]

justification for why it believes that LDEO's use of the Nucleus source 
model, which does not provide data above 2.5 kHz, is appropriate for 
determining the extents of the Level A harassment zones for mid-
frequency and high-frequency cetaceans.
    Response: Few broadband calibration studies are available to 
support the modeling of airgun spectra above 3 kHz (e.g., Tolstoy et 
al. 2004; Breitzke et al. 2008; Tolstoy et al. 2009). Measurements 
available indicate that most of the sound produced by airguns is below 
1 kHz (i.e., spectral levels drop off continuously above 1 kHz).
    Despite JASCO's AASM model predicting acoustic signatures of 
seismic airgun arrays up to 25 kHz, often their transmission loss 
calculations do not directly use these data to account for frequencies 
above 5 kHz because it is computationally intensive (Zeddies et al. 
2015). While NMFS agrees that the spectral levels above 3 kHz should 
not necessarily be assumed zero, better data are needed to evaluate if 
and how airguns at these frequencies are significantly contributing to 
noise-induced hearing loss for these two marine mammal hearing groups.
    For both MF and HF cetaceans, the TTS onset impulsive thresholds 
NMFS currently relies upon are derived directly from individual exposed 
to seismic sources (Finneran et al. 2002; Lucke et al. 2009). A more 
recent TTS study on harbor porpoises exposed to multiple airgun shots 
further supports the current TTS onset thresholds used to evaluate 
impulsive sources (Kastelein et al. 2017).
    The available TTS onset data do not indicate that airguns are 
contributing significantly to noise-induced hearing loss at higher 
frequencies in these two hearing groups. Specifically, Lucke et al. 
(2009) measured harbor porpoise hearing at 4, 32, and 100 kHz after 
exposure to a single airgun shot, with TTS onset only occurring at 4 
kHz. Similarly, Kastelein et al. (2017) measured a ~4.4 dB threshold 
shift only at 4 kHz, with hearing tested up to 8 kHz, for a harbor 
porpoise exposed to multiple airgun shots. Finally, Finneran et al. 
(2015) exposed bottlenose dolphins to multiple airgun shots and 
measured hearing thresholds up to 64 kHz, without measurable TTS onset 
observed. All these studies had measurements demonstrating spectral 
levels above 3 kHz for their airgun sources. For these reasons, NMFS 
believes that LDEO's use of the Nucleus source model is appropriate. 
NMFS appreciates the Commission's interest in this matter and will 
continue to evaluate the available information regarding spectral 
levels of airgun signals above 3 kHz.
    Comment 3. The Commission recommends that NMFS require USGS, in 
collaboration with LDEO, to re-estimate the proposed Level A and 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 (e.g., Gundalf Optimizer or AASM) and (3) an appropriate sound 
propagation model. Specifically, the Commission reiterates its belief 
that LDEO should be using the ray-tracing sound propagation model 
BELLHOP rather than the MATLAB code currently in use.
    Response: USGS's application (USGS, 2018) and the Federal Register 
notice of the proposed IHA (83 FR 25268; May 31, 2018) describe the 
applicant's approach to modeling Level A and Level B harassment zones. 
The model LDEO currently uses does not allow for the consideration of 
site-specific environmental parameters as recommended by the 
Commission.
    In summary, LDEO acquired field measurements for several array 
configurations at shallow, intermediate, and deep-water depths during 
acoustic verification studies conducted in the northern Gulf of Mexico 
(Tolstoy et al., 2009). Based on the empirical data from those studies, 
LDEO developed a sound propagation modeling approach that predicts 
received sound levels as a function of distance from a particular 
airgun array configuration in deep water. For this survey, LDEO modeled 
Level A and Level B harassment zones based on the empirically-derived 
measurements from the Gulf of Mexico calibration survey (Appendix H of 
NSF-USGS 2011). LDEO used the deep-water radii obtained from model 
results down to a maximum water depth of 2,000 m (Figure 2 and 3 in 
Appendix H of NSF-USGS 2011).
    In 2015, LDEO explored the question of whether the Gulf of Mexico 
calibration data described above adequately informs the model to 
predict harassment isopleths in other areas by conducting a 
retrospective sound power analysis of one of the lines acquired during 
LDEO'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 
an IHA issued for LDEO (see 80 FR 27635, May 14, 2015, Table 1). 
Briefly, the analysis presented in Crone (2015), specific to the survey 
site offshore New Jersey, confirmed that in-situ, site-specific 
measurements and estimates of 160 decibel (dB) and 180 dB isopleths 
collected by the hydrophone streamer of the R/V Marcus Langseth in 
shallow water were smaller than the modeled (i.e., predicted) zones for 
two seismic surveys conducted offshore New Jersey in shallow water in 
2014 and 2015. In that particular case, Crone's (2015) results showed 
that LDEO's modeled 180 dB and 160 dB zones were approximately 28 
percent and 33 percent larger respectively, than the in-situ, site-
specific measurements, thus confirming that LDEO's model was 
conservative in that case.
    The following is a summary of two additional analyses of in-situ 
data that support LDEO's use of the modeled Level A and Level B 
harassment zones in this particular case. In 2010, LDEO assessed the 
accuracy of their modeling approach by comparing the sound levels of 
the field measurements acquired in the Gulf of Mexico study to their 
model predictions (Diebold et al., 2010). They reported that the 
observed sound levels from the field measurements fell almost entirely 
below the predicted harassment radii curve for deep water (i.e., 
greater than 1,000 m; 3,280.8 ft) (Diebold et al., 2010). In 2012, LDEO 
used a similar process to model distances to isopleths corresponding to 
Level A and Level B harassment thresholds for a shallow-water seismic 
survey in the northeast Pacific Ocean off Washington State. LDEO 
conducted the shallow-water survey using a 6,600 in\3\ airgun 
configuration aboard the R/V Marcus Langseth and recorded the received 
sound levels on both the shelf and slope using the Langseth's 8 km 
hydrophone streamer. Crone et al. (2014) analyzed those received sound 
levels from the 2012 survey and confirmed that in-situ, site specific 
measurements and estimates of the 160 dB and 180 dB isopleths collected 
by the Langseth's hydrophone streamer in shallow water were two to 
three times smaller than LDEO's modeling approach had predicted. While 
the results confirmed the role of bathymetry in sound propagation, 
Crone et al. (2014) were also able to confirm that the empirical 
measurements from the Gulf of Mexico calibration survey (the same 
measurements used to inform LDEO's modeling approach for the planned 
surveys in the northwest Atlantic

[[Page 39695]]

Ocean) overestimated the size of the exclusion and buffer zones for the 
shallow-water 2012 survey off Washington State and were thus 
precautionary, in that particular case.
    NMFS continues to work with LDEO to address the issue of 
incorporating site-specific information for future authorizations for 
seismic surveys. However, LDEO's current modeling approach (supported 
by the three studies discussed previously) represents the best 
available information for NMFS to reach determinations for this IHA. As 
described earlier, the comparisons of LDEO's model results and the 
field data collected at multiple locations (i.e., the Gulf of Mexico, 
offshore Washington State, and offshore New Jersey) illustrate a degree 
of conservativeness built into LDEO's model for deep water, which NMFS 
expects to offset some of the limitations of the model to capture the 
variability resulting from site-specific factors. Based upon the best 
available information (i.e., the referenced studies, two of which are 
peer-reviewed, discussed in this response), NMFS finds that the Level A 
and Level B harassment zone calculations are reasonable and appropriate 
for use in this particular IHA.
    LDEO has conveyed to NMFS that additional modeling efforts to 
refine the process and conduct comparative analysis may be possible 
with the availability of research funds and other resources. Obtaining 
research funds is typically accomplished through a competitive process, 
including those submitted to U.S. Federal agencies. The use of models 
for calculating Level A and Level B harassment zones and for developing 
take estimates is not a requirement of the MMPA incidental take 
authorization process. Further, NMFS does not provide specific guidance 
on model parameters nor prescribe a specific model for applicants as 
part of the MMPA incidental take authorization process at this time, 
although we do review methods to ensure that they are adequate for 
reasonable prediction of take. There is a level of variability not only 
with parameters in the models, but also the uncertainty associated with 
data used in models, and therefore, the quality of the model results 
submitted by applicants. NMFS considers this variability when 
evaluating applications and the take estimates and mitigation measures 
that the model informs. NMFS takes into consideration the model used, 
and its results, in determining the potential impacts to marine 
mammals; however, it is just one component of the analysis during the 
MMPA authorization process as NMFS also takes into consideration other 
factors associated with the activity (e.g., geographic location, 
duration of activities, context, sound source intensity, etc.).
    Comment 4: The Commission recommends that NMFS require USGS to 
archive, analyze, and compare the in-situ data collected by the 
sonobuoys and hydrophone streamer to LDEO's modeling results for the 
extents of the Level A and B harassment zones based on the various 
airgun configurations and water depths to be surveyed and provide the 
data and results to NMFS.
    Response: NMFS will suggest that the USGS use its collected data to 
both analyze and compare with LDEO's modeling results and share with 
NMFS. However, NMFS does not deem it necessary to require USGS to use 
the in-situ data it collects from the sonobuoys and hydrophone streamer 
it deploys during its cruise. As stated in the response to Comment 2, 
NMFS continues to work with LDEO to address the issue of incorporating 
site-specific information for future authorizations for seismic 
surveys. Nevertheless, LDEO's Nucleus model has shown to be 
conservative when compared to in-situ, site specific measurements and 
estimates (Crone 2015). Therefore, NMFS asserts that the use of the 
Nucleus source model in its current state is appropriate.
    Comment 5: The Commission recommends that NMFS ensure that USGS 
calculated the numbers of takes appropriately based on the line-
kilometers to be surveyed in each of the 11 tracklines and the number 
of days it would take to survey each location, the associated 
ensonified areas, and site-specific densities--species-specific takes 
from each of the 11 locations should be summed to yield the total 
numbers of takes for each species.
    Response: The number of days are factored into the take estimates. 
To calculate take, USGS used 10 km x 10 km density grid blocks taken 
from Roberts et al. (2016) which were intersected with two different 
buffer zones. One buffer is equivalent to the largest Level A 
harassment zone and the other is equal to both the largest Level A 
harassment zone and Level B harassment zone (for the Optimal Survey) 
combined. As a result, the modeling method derived a take total for 
each 10 km x 10 km block the R/V Sharp will survey. Take totals for 
each block were each added (rounded at the end) to come up with the 
take estimates for each species. Due to the short duration (a few hours 
at most) that the R/V Sharp will conduct seismic operations in each 10 
km x 10 km survey block, the number of days (1 day per block) is 
factored into the take estimates.
    Comment 6: The Commission recommends that NMFS require USGS to 
provide in all future applications all relevant information regarding 
line-kilometers to be surveyed and days necessary to survey each 
location based on a presumed survey speed, associated ensonified areas, 
site-specific densities, and any other assumptions (including the 
assumed 25-percent contingency).
    Response: NMFS will continue to request as much information from 
applicants as necessary to determine if their take methodology is 
scientifically accurate. After NMFS's request, USGS provided NMFS and 
the Commission with more data to analyze the method used to estimate 
take during the survey. In reviewing these data with the density 
estimates provided in Roberts et al. (2016), NMFS determined that the 
methodology used for take calculation in the IHA application is 
appropriate. In all, USGS provided NMFS with enough information to 
effectively assess the generated take estimates. For future surveys, 
USGS will work to provide a technical guidance document that will 
better detail its take methodology using Geographic Information Systems 
(GIS) software.
    Comment 7: The Commission recommends that NMFS share its rounding 
criteria.
    Response: On June 27, 2018, NMFS provided the Commission with 
internal guidance on rounding and the consideration of additional 
factors in take estimation.
    Comment 8: The Commission recommends that NMFS condition the 
authorization to limit USGS's use of the echosounder during transits to 
and from the survey area except during calibration. In addition, the 
Commission recommends NMFS advise USGS that it needs to obtain 
additional authorization to take marine mammals while using an 
echosounder to collect gas hydrate data during transits to and from the 
survey area.
    Response: As stated in the IHA application, marine mammals would 
have to be either very close and remain near the sound source for many 
repeated pings to receive overall exposures sufficient to cause TTS 
onset (Lucke et al. 2009; Finneran and Schlundt 2010) from the 
fisheries echosounder. The echosounder used by USGS during the MATRIX 
survey will only transmit conically downward in a maximum 10 degree 
cone. Based on modeling by the U.S. Geological Survey, the area 
ensonified at greater than 160 dB re: 1 [mu]Pa (rms) is 0.0407 square 
kilometers (0.0119 square nautical

[[Page 39696]]

miles), corresponding to a maximum of approximately 72 meters (236.2 
feet) athwartship and approximately 650 meters (2,132.6 feet) below the 
research vessel (See Figure 18 of USGS 2018). This, combined with the 
vessel strike avoidance measures stipulated in section 4(f) of the IHA 
for the USGS MATRIX survey allows NMFS to concur that the minimal use 
of a scientific echosounder during transits is not reasonably likely to 
result in the incidental taking of marine mammals pursuant to the MMPA.

Description of Marine Mammals in the Area of Specified Activities

    A detailed description of the species likely to be affected by 
USGS's geophysical survey, including brief introductions to the species 
and relevant stocks as well as available information regarding 
population trends and threats, and information regarding local 
occurrence, were provided in the Federal Register notice for the 
proposed IHA (83 FR 25268; May 31, 2018); 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' website (https://www.fisheries.noaa.gov/topic/population-assessments/marine-mammals) for generalized species accounts. All 
species that could potentially occur in the planned survey area are 
included in Table 2. However, density estimates in Roberts et al. 
(2016) present very low density estimates within the proposed action 
area during the month of August for north Atlantic right whale, harbor 
porpoise, minke whale, Bryde's whale, blue whale, and white-beaked 
dolphin (See Table 6 of IHA Application). This, in combination with the 
short length of the cruise and low level airguns provide reasonable 
evidence that take authorization is not necessary, nor should they be 
authorized for these species. Species with expected take are discussed 
below.

                                              Table 2--Marine Mammals That Could Occur in the Project Area
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                 NMFS stock
                                                                               ESA/MMPA        abundance (CV,                                     Annual
           Common name              Scientific name           Stock             status;      Nmin, most recent    Predicted abundance     PBR      M/SI
                                                                             strategic (Y/   abundance survey)          (CV) \5\                   \3\
                                                                                N) \1\              \2\
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                          Order Cetartiodactyla--Cetacea--Superfamily Mysticeti (baleen whales)
                                                                    Family Balaenidae
--------------------------------------------------------------------------------------------------------------------------------------------------------
North Atlantic right whale......  Eubalaena glacialis  Western North        E/D; Y          458 (n/a; 455; n/a)  334 (0.25)...........      1.4       36
                                                        Atlantic (WNA).
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                            Family Balaenopteridae (rorquals)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Humpback whale..................  Megaptera            Gulf of Maine......  -; N            335 (.42; 239;       1,637 (0.07).........      3.7      8.5
                                   novaeangliae                                              2012).
                                   novaeangliae.
Minke whale.....................  Balaenoptera         Canadian East Coast  -; N            2,591 (0.81; 1,425;  2,112 (0.05).........       14        9
                                   acutorostrata                                             2011).
                                   acutorostrata.
Bryde's whale...................  B. edeni brydei....  None defined \4\...  -; n/a          n/a................  7 (0.58).............      n/a      n/a
Sei whale.......................  B. borealis          Nova Scotia........  E/D; Y          357 (0.52; 236;      98 (0.25)............      0.5      0.8
                                   borealis.                                                 2011).
Fin whale.......................  B. physalus          WNA................  E/D; Y          1,618 (0.33; 1,234;  4,633 (0.08).........      2.5     2.65
                                   physalus.                                                 2011).
Blue whale......................  B. musculus          WNA................  E/D; Y          Unknown (n/a; 440;   11 (0.41)............      0.9      Unk
                                   musculus.                                                 n/a).
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                                            Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
                                                                   Family Physeteridae
--------------------------------------------------------------------------------------------------------------------------------------------------------
Sperm whale.....................  Physeter             North Atlantic.....  E/D; Y          2,288 (0.28; 1,815;  5,353 (0.12).........      3.6      0.8
                                   macrocephalus.                                            2011).
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                                                                     Family Kogiidae
--------------------------------------------------------------------------------------------------------------------------------------------------------
Pygmy sperm whale...............  Kogia breviceps....  WNA................  -; N            3,785 (0.47; 2,598;  678 (0.23)...........       21      3.5
                                                                                             2011).
Dwarf sperm whale...............  K. sima............  WNA................  -; N
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                            Family Ziphiidae (beaked whales)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Cuvier's beaked whale...........  Ziphius cavirostris  WNA................  -; N            6,532 (0.32; 5,021;  14,491(0.17).........       50      0.4
                                                                                             2011).
Gervais beaked whale............  Mesoplodon           WNA................  -; N            7,092 (0.54; 4,632;  .....................       46      0.2
                                   europaeus.                                                2011).
Blainville's beaked whale.......  M. densirostris....  WNA................  -; N
Sowerby's beaked whale..........  M. bidens..........  WNA................  -; N
True's beaked whale.............  M. mirus...........  WNA................  -; N
Northern bottlenose whale.......  Hyperoodon           WNA................  -; N            Unknown............  90 (0.63)............   Undet.        0
                                   ampullatus.
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                   Family Delphinidae
--------------------------------------------------------------------------------------------------------------------------------------------------------
Rough-toothed dolphin...........  Steno bredanensis..  WNA................  -; N            271 (1.0; 134;       532 (0.36)...........      1.3        0
                                                                                             2011).
Common bottlenose dolphin.......  Tursiops truncatus   WNA Offshore.......  -; N            77,532 (0.40;        97,476 (0.06)........      561     39.4
                                   truncatus.                                                56,053; 2011).
Clymene dolphin.................  Stenella clymene...  WNA................  -; N            Unknown............  12,515 (0.56)........   Undet.        0
Atlantic spotted dolphin........  S. frontalis.......  WNA................  -; N            44,715 (0.43;        55,436 (0.32)........      316        0
                                                                                             31,610; 2011).
Pantropical spotted dolphin.....  S. attenuata         WNA................  -; N            3,333 (0.91; 1,733;  4,436 (0.33).........       17        0
                                   attenuata.                                                2011).
Spinner dolphin.................  S. longirostris      WNA................  -; N            Unknown............  262 (0.93)...........   Undet.        0
                                   longirostris.
Striped dolphin.................  S. coeruleoalba....  WNA................  -; N            54,807 (0.3;         75,657 (0.21)........      428        0
                                                                                             42,804; 2011).
Short-beaked common dolphin.....  Delphinus delphis    WNA................  -; N            70,184 (0.28;        86,098 (0.12)........      557      437
                                   delphis.                                                  55,690; 2011).
Fraser's dolphin................  Lagenodelphis hosei  WNA................  -; N            Unknown............  492 (0.76)...........   Undet.        0
Atlantic white-sided dolphin....  Lagenorhynchus       WNA................  -; N            48,819 (0.61;        37,180 (0.07)........      304       57
                                   acutus.                                                   30,403; 2011).

[[Page 39697]]

 
Risso's dolphin.................  Grampus griseus....  WNA................  -; N            18,250 (0.46;        7,732 (0.09).........      126     43.2
                                                                                             12,619; 2011).
Melon-headed whale..............  Peponocephala        WNA................  -; N            Unknown............  1,175 (0.50).........   Undet.        0
                                   electra.
Pygmy killer whale..............  Feresa attenuata...  WNA................  -; N            Unknown............  N/A..................   Undet.        0
False killer whale..............  Pseudorca            WNA................  -; Y            442 (1.06; 212;      95 (0.84)............      2.1     Unk.
                                   crassidens.                                               2011).
Killer whale....................  Orcinus orca.......  WNA................  -; N            Unknown............  11...................   Undet.        0
Short-finned pilot whale........  Globicephala         WNA................  -; Y            21,515 (0.37;        18,977 (0.11)........      159      192
                                   macrorhynchus.                                            15,913; 2011).
Long-finned pilot whale.........  G. melas melas.....  WNA................  -; Y            5,636 (0.63; 3,464;  .....................       35       38
                                                                                             2011).
White-beaked dolphin............  Lagenorhynchus       WNA................  -; N            2,003 (0.94; 1,023;  39 (0.42)............       10        0
                                   albirostris.                                              2007).
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                             Family Phocoenidae (porpoises)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Harbor porpoise.................  Phocoena phocoena    Gulf of Maine/Bay    -; N            79,833 (0.32;        45,089 (0.12)........      706      307
                                   phocoena.            of Fundy.                            61,415; 2011).
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Endangered Species Act (ESA) status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-) indicates that the species is not listed
  under the ESA or designated as depleted under the MMPA. Under the MMPA, a strategic stock is one for which the level of direct human-caused mortality
  exceeds PBR or which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed
  under the ESA is automatically designated under the MMPA as depleted and as a strategic stock.
\2\ NMFS marine mammal stock assessment reports online at: www.nmfs.noaa.gov/pr/sars/. CV is coefficient of variation; Nmin is the minimum estimate of
  stock abundance.
\3\ These values, found in NMFS' SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined (e.g., commercial
  fisheries, ship strike). Annual M/SI often cannot be determined precisely and is in some cases presented as a minimum value or range. A CV associated
  with estimated mortality due to commercial fisheries is presented in some cases.
\4\ Bryde's whales are occasionally reported off the southeastern U.S. and southern West Indies. NMFS defines and manages a stock of Bryde's whales
  believed to be resident in the northern Gulf of Mexico, but does not define a separate stock in the Atlantic Ocean.
\5\ Predicted mean abundance derived from Roberts et al. (2016).
Note--Italicized species in the ``Common Name ``column are not authorized for take.

Potential Effects of Specified Activities on Marine Mammals and Their 
Habitat

    The effect of stressors associated with the specified activities 
(e.g., seismic airguns) has the potential to result in behavioral 
harassment of marine mammals in the vicinity of the action areas. The 
Federal Register notice for the proposed IHA (83 FR 25268; May 31, 
2018) included a discussion of the effects of such disturbance on 
marine mammals, therefore that information is not repeated here.
    NMFS described potential impacts to marine mammal habitat in detail 
in our Federal Register notice of proposed authorization (83 FR 25268; 
May 31, 2018). In summary, due to the short duration of the activities 
and the relatively small area of the habitat that the survey covers, 
the impacts to marine mammal habitat are not expected to cause 
significant or long-term negative consequences for individual marine 
mammals or their populations.

Estimated Take

    This section provides an estimate of the number of incidental takes 
for authorization through this IHA, which will inform both NMFS's 
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 will be by Level B harassment only, in the form of 
disruption of behavioral patterns for individual marine mammals 
resulting from exposure to airguns. Based on the nature of the 
activity, the cryptic behavior and low density for Kogia spp. (the only 
high-frequency cetacean authorized for take) within the action areas, 
and the anticipated effectiveness of the mitigation measures (i.e., 
shutdown and a minimum vessel distance of 100 m from large whales--
discussed in detail below in the Mitigation section), Level A 
harassment is neither anticipated nor authorized. As described 
previously, no mortality is anticipated or authorized for this 
activity. Below we describe how the take is estimated.
    Described in the most basic way, we estimate take by considering: 
(1) Acoustic thresholds above which NMFS believes the best available 
science indicates marine mammals will be behaviorally harassed or incur 
some degree of permanent hearing impairment; (2) the area or volume of 
water that will be ensonified above these levels in a day; (3) the 
density or occurrence of marine mammals within these ensonified areas; 
and, (4) and the number of days of activities. Below, we describe these 
components in more detail and present the take estimate.

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 will 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

[[Page 39698]]

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 decibels (dB) re 1 micro pascal ([mu]Pa) root 
mean square (rms) for continuous (e.g., vibratory pile-driving, 
drilling) and above 160 dB re 1 [mu]Pa (rms) for non-explosive 
impulsive (e.g., seismic airguns) sources. USGS's activity includes the 
use of impulsive seismic sources. Therefore, the 160 dB re 1 [mu]Pa 
(rms) criteria is applicable for analysis of Level B harassment.
    Level A harassment for non-explosive sources--NMFS' Technical 
Guidance for Assessing the Effects of Anthropogenic Sound on Marine 
Mammal Hearing (Technical Guidance, 2016) identifies dual criteria to 
assess auditory injury (Level A harassment) to five different marine 
mammal groups (based on hearing sensitivity) as a result of exposure to 
noise from two different types of sources (impulsive or non-impulsive). 
As described above, USGS's activity includes the use of intermittent 
and 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 2016 Technical 
Guidance, which may be accessed at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance.

                     Table 3--Thresholds Identifying the Onset of Permanent Threshold Shift
----------------------------------------------------------------------------------------------------------------
                                                     PTS onset acoustic thresholds * (received level)
             Hearing group              ------------------------------------------------------------------------
                                                  Impulsive                         Non-impulsive
----------------------------------------------------------------------------------------------------------------
Low-Frequency (LF) Cetaceans...........  Cell 1: Lpk,flat: 219 dB;   Cell 2: LE,LF,24h: 199 dB.
                                          LE,LF,24h: 183 dB.
Mid-Frequency (MF) Cetaceans...........  Cell 3: Lpk,flat: 230 dB;   Cell 4: LE,MF,24h: 198 dB.
                                          LE,MF,24h: 185 dB.
High-Frequency (HF) Cetaceans..........  Cell 5: Lpk,flat: 202 dB;   Cell 6: LE,HF,24h: 173 dB.
                                          LE,HF,24h: 155 dB.
Phocid Pinnipeds (PW) (Underwater).....  Cell 7: Lpk,flat: 218 dB;   Cell 8: LE,PW,24h: 201 dB.
                                          LE,PW,24h: 185 dB.
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]Pa2s. In this Table, thresholds are abbreviated to reflect American National
  Standards Institute standards (ANSI 2013). However, peak sound pressure is defined by ANSI as incorporating
  frequency weighting, which is not the intent for this Technical Guidance. Hence, the subscript ``flat'' is
  being included to indicate peak sound pressure should be flat weighted or unweighted within the generalized
  hearing range. The subscript associated with cumulative sound exposure level thresholds indicates the
  designated marine mammal auditory weighting function (LF, MF, and HF cetaceans, and PW and OW pinnipeds) and
  that the recommended accumulation period is 24 hours. The cumulative sound exposure level thresholds could be
  exceeded in a multitude of ways (i.e., varying exposure levels and durations, duty cycle). When possible, it
  is valuable for action proponents to indicate the conditions under which these acoustic thresholds will be
  exceeded.

Ensonified Area

    Here, we describe operational and environmental parameters of the 
activity that will feed into identifying the area ensonified above the 
acoustic thresholds
    The survey will entail the use of a 4-airgun array with a total 
maximum discharge of 840 cubic inches (in\3\) for operations that occur 
at water depths greater than 1,000 m and 420 in\3\ for operations that 
occur at water depths of 1,000 m or less with at a tow depth of 3 m. 
The distances to the predicted isopleths corresponding to the threshold 
for Level B harassment (160 dB re 1 [mu]Pa) were calculated for both 
array configurations based on results of modeling performed by LDEO 
using the Nucleus Model. Received sound levels were predicted by LDEO's 
model (Diebold et al., 2010) as a function of distance from the airgun 
array. The LDEO modeling approach uses ray tracing for the direct wave 
traveling from the array to the receiver and its associated source 
ghost (reflection at the air-water interface in the vicinity of the 
array), in a constant-velocity half-space (infinite homogeneous ocean 
layer unbounded by a seafloor). In addition, propagation measurements 
of pulses from a 36-airgun array at a tow depth of 6 m have been 
reported in deep water (~1,600 m), intermediate water depth on the 
slope (~600-1,100 m), and shallow water (~50 m) in the Gulf of Mexico 
in 2007-2008 (Tolstoy et al., 2009; Diebold et al., 2010). The 
estimated distances to Level B harassment isopleths for the two 
configurations of the R/V Hugh R. Sharp airgun array are shown in Table 
4.

 Table 4--Modeled Radial Distances [m (km\2\)] From R/V Hugh R. Sharp's Airgun Array to Isopleths Corresponding
                                        to Level B harassment thresholds
----------------------------------------------------------------------------------------------------------------
                                                                                                 Predicted RMS
                                                                                                   Radii (m)
        Source and volume                 Tow depth (m)                Water depth (m)       -------------------
                                                                                                    160 dB
----------------------------------------------------------------------------------------------------------------
Base Configuration                                           3                        >1,000  1,091 m (3.7
 (Configuration 1): Four 105                                                       100-1,000   km\2\) \1\
 in\3\ GI-guns.                                                                               1,637 m (8.42
                                                                                               km\2\) \2\
GG Configuration(Configuration                               3                        >1,000  1,244 m (4.86
 2): Four 210 in\3\ GI-guns.                                                       100-1,000   km\2\) \1\
                                                                                              1,866 m (10.94
                                                                                               km\2\) \2\
----------------------------------------------------------------------------------------------------------------
\1\ Distance is based on L-DEO model results.
\2\ Distance is based on L-DEO model results with a 1.5 x correction factor between deep and intermediate water
  depths.

    For modeling of radial distances to predicted isopleths 
corresponding to harassment thresholds in deep water (>1,000 m), LDEO 
used the deep-water radii for various SELs obtained from LDEO model 
results down to a

[[Page 39699]]

maximum water depth of 2,000 m (see Figures 4 and 5 in the IHA 
application). LDEO's modeling methodology is described in greater 
detail in the IHA application (USGS, 2018) and we refer to the reader 
to that document rather than repeating it here.
    Predicted distances to Level A harassment isopleths, which vary 
based on marine mammal functional hearing groups (Table 3), were 
calculated based on modeling performed by LDEO using the Nucleus 
software program and the NMFS User Spreadsheet, described below. The 
updated acoustic thresholds for impulsive sounds (such as airguns) 
contained in the Technical Guidance (NMFS, 2016) were presented as dual 
metric acoustic thresholds using both SELcum and peak sound 
pressure level metrics. As dual metrics, NMFS considers onset of PTS 
(Level A harassment) to have occurred when either one of the two 
metrics is exceeded (i.e., metric resulting in the largest isopleth). 
The SELcum metric considers both level and duration of 
exposure, as well as auditory weighting functions by marine mammal 
hearing group. In recognition of the fact that the requirement to 
calculate Level A harassment ensonified areas could be more technically 
challenging to predict due to the duration component and the use of 
weighting functions in the new SELcum thresholds, NMFS 
developed an optional User Spreadsheet that includes tools to help 
predict a simple isopleth that can be used in conjunction with marine 
mammal density or occurrence to facilitate the estimation of take 
numbers.
    The values for SELcum and peak SPL for the R/V Hugh R. 
Sharp airgun array were derived from calculating the modified farfield 
signature (Table 5). The farfield signature is often used as a 
theoretical representation of the source level. To compute the farfield 
signature, the source level is estimated at a large distance below the 
array (e.g., 9 km), and this level is back projected mathematically to 
a notional distance of 1 m from the array's geometrical center. 
However, when the source is an array of multiple airguns separated in 
space, the source level from the theoretical farfield signature is not 
necessarily the best measurement of the source level that is physically 
achieved at the source (Tolstoy et al., 2009). Near the source (at 
short ranges, distances <1 km), the pulses of sound pressure from each 
individual airgun in the source array do not stack constructively, as 
they do for the theoretical farfield signature. The pulses from the 
different airguns spread out in time such that the source levels 
observed or modeled are the result of the summation of pulses from a 
few airguns, not the full array (Tolstoy et al., 2009). At larger 
distances, away from the source array center, sound pressure of all the 
airguns in the array stack coherently, but not within one time sample, 
resulting in smaller source levels than the source level derived from 
the farfield signature. Because the farfield signature does not take 
into account the array effect near the source and is calculated as a 
point source, the modified farfield signature is a more appropriate 
measure of the sound source level for distributed sound sources, such 
as airgun arrays. Though the array effect is not expected to be as 
pronounced in the case of a 4-airgun array as it will be with a larger 
airgun array, the modified farfield method is considered more 
appropriate than use of the theoretical farfield signature.
    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 R/V Hugh R. Sharp's airgun array 
(modeled in 1 Hz bands) was used to make adjustments (dB) to the 
unweighted spectrum levels, by frequency, according to the weighting 
functions for each relevant marine mammal hearing group. These 
adjusted/weighted spectrum levels were then converted to pressures 
([mu]Pa) in order to integrate them over the entire broadband spectrum, 
resulting in broadband weighted source levels by hearing group that 
could be directly incorporated within the User Spreadsheet (i.e., to 
override the Spreadsheet's more simple weighting factor adjustment). 
Using the User Spreadsheet's ``safe distance'' methodology for mobile 
sources (described by Sivle et al., 2014) with the hearing group-
specific weighted source levels, and inputs assuming spherical 
spreading propagation, a source velocity of 2.06 m/second and a shot 
interval of 12.15 seconds, potential radial distances to auditory 
injury zones were calculated for Peak SPLflat and 
SELcum thresholds, for both array configurations. Source 
level Inputs to the User Spreadsheet are shown in Table 5 (inputs to 
the user spreadsheet also included the source velocity and shot 
interval listed above). Outputs from the User Spreadsheet in the form 
of estimated distances to Level A harassment isopleths are shown in 
Table 6. The larger distance of the dual criteria (SELcum or 
Peak SPLflat) is used for estimating takes by Level A 
harassment. The weighting functions used are shown in Appendix C of the 
IHA application.

                                     Table 5--Modeled Source Levels ** (dB) for the R/V Hugh R. Sharp's Airgun Array
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                           Configuration   Configuration   Configuration   Configuration   Configuration   Configuration
                                                            1 * 4 x 105     1 * 4 x 105     2 * 4 x 210     2 * 4 x 210     3 * 2 x 105     3 * 2 x 105
                Functional hearing group                   cu\3\ SELcum     cu\3\ Peak     cu\3\ SELcum     cu\3\ Peak     cu\3\ SELcum     cu\3\ Peak
                                                                              SPLflat                         SPLflat                         SPLflat
--------------------------------------------------------------------------------------------------------------------------------------------------------
Low frequency cetaceans (Lpk,flat: 219 dB; LE,LF,24h:                214             239             215             240             208             235
 183 dB)................................................
Mid frequency cetaceans (Lpk,flat: 230 dB; LE,MF,24h:                214             N/A             215             N/A             208             234
 185 dB)................................................
High frequency cetaceans (Lpk,flat: 202 dB; LE,HF,24h:               214             239             215             240             208             235
 155 dB)................................................
--------------------------------------------------------------------------------------------------------------------------------------------------------
* All configurations have the following airgun specifications: 3 m tow depth; 2 m separation in the fore-aft direction; 8.6 m separation in the port
  (starboard direction).
 **Source Levels were rounded to nearest whole number. See Appendix C of IHA Application for exact value.


       Table 6--Modeled Radial Distances [m(m2)] From R/V Hugh R. Sharp's Airgun Array to Isopleths Corresponding to Level A Harassment Thresholds
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                    Configuration 1 4 x
                               Configuration 1 4 x   105 cu\3\ 3 m tow   Configuration 2 4 x   Configuration 2 4   Configuration 3 2   Configuration 3 2
   Functional hearing group      105 cu\3\ SELcum   depth, Peak SPLflat    210 cu\3\ SELcum    x 210 cu\3\ Peak   x 105 cu\3\ SELcum   x 105 cu\3\ Peak
                                                                                                    SPLflat                                 SPLflat
--------------------------------------------------------------------------------------------------------------------------------------------------------
Low frequency cetaceans        31 m (3,019 m\2\)..  10.03 m (316 m\2\).  39.5 m (4,902 m\2\)  11.56 m (420 m\2\)  10.6 m (353 m\2\).  6.52 m (134 m\2\)
 (Lpk,flat: 219 dB;
 LE,LF,24h: 183 dB).
Mid frequency cetaceans        0..................  0..................  0..................  0.................  0.................  1.58 m (8 m\2\)
 (Lpk,flat: 230 dB;
 LE,MF,24h: 185 dB).

[[Page 39700]]

 
High frequency cetaceans       0..................  70.43 m (15743.22    0.1(.03 m\2\)......  80.50 m (20,358     0.................  42.32 m (5,627
 (Lpk,flat: 202 dB;                                  m\2\).                                    m\2\).                                  m\2\)
 LE,HF,24h: 155 dB).
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Note that because of some of the assumptions included in the 
methods used, isopleths produced may be overestimates to some degree. 
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 this seismic survey, the User 
Spreadsheet predicts the closest distance at which a stationary animal 
would not incur PTS if the sound source traveled by the animal in a 
straight line at a constant speed.

Marine Mammal Occurrence

    In this section we provide the information about the presence, 
density, or group dynamics of marine mammals that will inform the take 
calculations. The best available scientific information was considered 
in conducting marine mammal exposure estimates (the basis for 
estimating take). For all cetacean species, densities calculated by 
Roberts et al. (2016) were used. These represent the most comprehensive 
and recent density data available for cetacean species in the survey 
area. Roberts et al. (2016) retained 21,946 cetacean sightings for 
analysis, omitted 4,786 sightings, and modeled 25 individual species 
and 3 multi-species guilds. In order to develop density models for 
species, Roberts et al. (2016) used an approach known as density 
surface modeling, as seen in DoN (2007) and Roberts et al. (2016). This 
couples traditional distance sampling with multivariate regression 
modeling to produce density maps predicted from fine-scale 
environmental covariates (e.g., Becker et al., 2014).
    In addition to the density information provided by Roberts et al. 
(2016), best available data on average group sizes taken from sightings 
in the western North Atlantic were also used. This is discussed more in 
the section below.

Take Calculation and Estimation

    Here we describe how the information provided above is brought 
together to produce a quantitative take estimate. To estimate marine 
mammal exposures, the USGS used published, quantitative density models 
by Roberts et al. (2016) for the Survey Area, which is entirely within 
the U.S. EEZ. These models are provided at 10 km x 10 km resolution in 
ArcGIS compatible IMG grids on the Duke University cetacean density 
website (https://seamap.env.duke.edu/models/Duke-EC-GOM-2015). When 
available, the cetacean density models for Month 8 (August) were used. 
Otherwise, the generic annual density model was employed. Only a single 
density model is provided for the Kogia genus (dwarf and sperm pygmy 
whales), beaked whale guild (Blainville's, Cuvier's, Gervais', 
Sowerby's, and True's beaked whales), and for pilot whales 
(Globicephala spp.).
    To determine takes, the USGS combined the Duke density grids with 
the zones corresponding to the Level A and Level B harassment 
thresholds (See Tables 4 and 6) arrayed on either side of each 
exemplary seismic line and linking/interseismic line. The takes by 
Level B and Level A harassment for each species in each 10 km x 10 km 
block of the IMG density grids were calculated based on the fractional 
area of each block intersected by the Level A and Level B harassment 
zones for LF, MF, and HF cetaceans. Summing takes along all of the 
lines yields the total take for each species for the action for the 
Base (Configuration 1) and Optimal (Configuration 2) surveys. The 
method also yields take for each survey line individually, allowing 
examination of those exemplary lines that will yield the largest or 
smallest take. No Level A harassment takes were calculated while using 
this method.
    As indicated earlier, estimated numbers of individuals potentially 
exposed to sound above the Level B harassment threshold are based on 
the 160-dB re 1[mu]Pa (rms) criterion for all cetaceans. It is assumed 
that marine mammals exposed to airgun sounds that strong could change 
their behavior sufficiently to be considered taken by harassment. Table 
7 shows the estimates of the number of cetaceans that potentially could 
be exposed to >=160 dB re 1 [mu]Pa (rms) during the action for the Base 
Survey and the Optimal Survey. The takes in Table 7 represents 25 
percent more than the number of takes calculated using the ArcGIS-based 
quantitative method devised by the USGS. This was used to account for 
potential additional seismic operations that may occur after repeat 
coverage of any areas where initial data quality is sub-standard.
    Also, as shown in Table 7, rough toothed dolphin, sei whale, and 
humpback whale calculated takes were increased to account for the 
average size of one group for each species. Takes for rare species of 
marine mammals in the action area were also increased to the average 
size of one group. Rare species that could be encountered and taken 
during the surveys are not presented in Table 7, but are presented in 
Table 8. These species were omitted from Table 7 due to low calculated 
incidents of potential exposures (i.e., less than the average group 
size). As a result, NMFS relied on average group size data to authorize 
the take of a single group of these species as a precautionary measure 
in case the survey encounters them. This is discussed further below 
Table 7.
    The calculated takes in Table 7 and 8 also assume that the surveys 
will be completed. However, it is unlikely that the entire survey 
pattern (exemplary lines plus 50 percent of the interseismic, linking 
lines) will be completed given the limitations on ship time, likely 
logistical challenges (compressor and GI gun repairs), time spent on 
transits and refueling, and the historical problems with weather during 
August in the western North Atlantic. The USGS's calculated timelines 
indicate that 25 days, including contingency, could be required to 
complete the full survey pattern. However, only 22 days or fewer will 
be scheduled for this USGS survey. The lines that are actually acquired 
will be dependent on weather, strength of the Gulf Stream (affects 
ability to tow the streamer in the appropriate geometry), and other 
considerations.

[[Page 39701]]



                                 Table 7--Calculated Incidents of Potential Exposure for Level B and Level A Harassment
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                         Optimal survey           Max Level B take
                            Species                             --------------------------------   for optimal or    Take (all Level      Take as % of
                                                                     Level A         Level B     base surveys +25%        B) \6\            pop.\1\
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                 Low Frequency Cetaceans
--------------------------------------------------------------------------------------------------------------------------------------------------------
Humpback whale.................................................               0               0                  0              \5\ 3               <0.1
Sei whale......................................................               0               1                  1              \7\ 3               2.04
Fin whale......................................................               0               4                  5                  5                0.1
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                 Mid-Frequency Cetaceans
--------------------------------------------------------------------------------------------------------------------------------------------------------
Sperm whale....................................................               0             128                161                161                2.9
Cuvier's beaked whale..........................................               0         \2\ 103            \2\ 128            \2\ 128               <0.1
True's beaked whale............................................               0
Gervais beaked whale...........................................               0
Sowerby's beaked whale.........................................               0
Blainville's beaked whale......................................               0
Rough-toothed dolphin..........................................               0               5                  6             \3\ 10                1.9
Common bottlenose dolphin......................................               0             606                757                757                0.8
Pantropical spotted dolphin....................................               0              40                 50                 50                1.1
Atlantic spotted dolphin.......................................               0           1,278              1,598              1,598                2.9
Striped dolphin................................................               0           1,167              1,459              1,459                1.9
Short-beaked common dolphin....................................               0           1,296              1,620              1,620                1.9
Risso's dolphin................................................               0             189                237                237                  3
Long-finned pilot whale........................................               0         \4\ 231                  0            \4\ 288                1.5
Short-finned pilot whale.......................................               0               0                  0
Clymene's dolphin..............................................               0              97                  0                122                  1
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                High-Frequency Cetaceans
--------------------------------------------------------------------------------------------------------------------------------------------------------
Pygmy/dwarf sperm whale........................................               0               7                  0                  9                0.2
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Based on mean abundance estimates from Roberts et al. (2016).
\2\ Values for density, take number, and percentage of population for authorization are for all beaked whales combined.
\3\ Based on one average group size for rough toothed dolphin (Jefferson 2015).
\4\ Values for density, take number, and percentage of population for authorization are for short-finned and long-finned pilot whales combined.
\5\ Based on one average group size for humpback whales (CETAP 1982). Summer seasonal sightings compiled from the OBIS database (See Figure 6 of IHA
  Application) show that humpback whales have been seen in the northern part of the action area during August.
\6\ Values are the same take numbers shown in Table 8 below. Table 8 includes take of rare species discussed below.
\7\ Based on one average group size for sei whale in the western Atlantic (CETAP 1982).

    Certain species potentially present in the survey areas are 
expected to be encountered only extremely rarely, if at all. Although 
Roberts et al. (2016) provide density models for these species (with 
the exception of the pygmy killer whale), due to the small numbers of 
sightings that underlie these models' predictions we believe it 
appropriate to account for the small likelihood that these species will 
be encountered by assuming that one group of each of these species 
might be encountered once by a given survey. With the exception of the 
northern bottlenose whale, none of these species should be considered 
cryptic (i.e., difficult to observe when present) versus rare (i.e., 
not likely to be present). Average group size was determined by 
considering known sightings in the western North Atlantic (CETAP, 1982; 
Hansen et al, 1994; NMFS, 2010a, 2011, 2012, 2013a, 2014, 2015a; Waring 
et al., 2007, 2015). It is important to note that our authorization of 
take equating to harassment of one group of each of these species is 
not equivalent to expected exposure. We do not expect that these rarely 
occurring (in the survey area) species will be exposed at all. 
Nonetheless, we are providing USGS with authorization to take these 
species, consistent with the terms of this IHA, in the unlikely event 
they are encountered. We provide a brief description for each of these 
species below.
    Northern Bottlenose Whale--Northern bottlenose whales are 
considered extremely rare in U.S. Atlantic waters, with only five NMFS 
sightings. The southern extent of distribution is generally considered 
to be approximately Nova Scotia (though Mitchell and Kozicki (1975) 
reported stranding records as far south as Rhode Island), and there 
have been no sightings within the survey areas. Whitehead and Wimmer 
(2005) estimated the size of the population on the Scotian Shelf at 163 
whales (95 percent CI 119-214). Whitehead and Hooker (2012) report that 
northern bottlenose whales are found north of approximately 37.5[deg] N 
and prefer deep waters along the continental slope. Roberts et al. 
(2016) produced a stratified density model on the basis of four 
sightings in the vicinity of Georges Bank (Roberts et al., 2015b). The 
five sightings in U.S. waters yield a mean group size of 2.2 whales, 
while MacLeod and D'Amico report a mean group size of 3.6. Here, we 
authorize take of one group with a maximum group size of four whales.
    Killer Whale--Killer whales are also considered rare in U.S. 
Atlantic waters (Katona et al., 1988; Forney and Wade, 2006), 
constituting 0.1 percent of marine mammal sightings in the 1978-81 
Cetacean and Turtle Assessment Program surveys (CETAP, 1982). Roberts 
et al. (2016) produced a stratified density model on the basis of four 
killer whale sightings (Roberts et al., 2015g), though Lawson and 
Stevens (2014) provide a minimum abundance estimate of 67 photo-
identified individual killer whales. Available information suggests 
that survey encounters with killer whales will be unlikely but could 
occur anywhere within the survey area and at any time of year (e.g., 
Lawson and Stevens, 2014). Silber et al. (1994) reported observations 
of two and 15 killer whales in the Gulf of California (mean group size 
8.5), while May-Collado et al. (2005) described mean group size of 3.6 
whales off the Pacific coast of Costa Rica. Based on 12 CETAP sightings 
and one group observed during NOAA surveys (CETAP, 1982; NMFS, 2014), 
the average group size in the Atlantic is 6.8 whales. Therefore, we

[[Page 39702]]

authorize take of one group with a maximum group size of seven whales.
    False Killer Whale--Although records of false killer whales from 
the U.S. Atlantic are uncommon, a combination of sighting, stranding, 
and bycatch records indicates that this species does occur in the 
western North Atlantic (Waring et al., 2015). Baird (2009) suggests 
that false killer whales may be naturally uncommon throughout their 
range. Roberts et al. (2016) produced a stratified density model on the 
basis of two false killer whale sightings (Roberts et al., 2015m), and 
NMFS produced the first abundance estimate for false killer whales on 
the basis of one sighting during 2011 shipboard surveys (Waring et al., 
2015). Similar to the killer whale, we believe survey encounters will 
be unlikely but could occur anywhere within the survey area and at any 
time of year. Mullin et al. (2004) reported a mean false killer whale 
group size of 27.5 from the Gulf of Mexico, and May-Collado et al. 
(2005) described mean group size of 36.2 whales off the Pacific coast 
of Costa Rica. The few sightings from CETAP (1982) and from NOAA 
shipboard surveys give an average group size of 10.3 whales. As a 
precaution, we authorize take of one group with a maximum group size of 
28 whales, as reported from the Gulf of Mexico.
    Pygmy Killer Whale--The pygmy killer whale is distributed worldwide 
in tropical to sub-tropical waters, and is assumed to be part of the 
cetacean fauna of the tropical western North Atlantic (Jefferson et 
al., 1994; Waring et al., 2007). Pygmy killer whales are rarely 
observed by NOAA surveys outside the Gulf of Mexico--one group was 
observed off of Cape Hatteras in 1992--and the rarity of such sightings 
may be due to a naturally low number of groups compared to other 
cetacean species (Waring et al., 2007). NMFS has never produced an 
abundance estimate for this species and Roberts et al. (2016) were not 
able to produce a density model for the species. The 1992 sighting was 
of six whales; therefore, we authorize take of one group with a maximum 
group size of six whales.
    Melon-headed Whale--Similar to the pygmy killer whale, the melon-
headed whale is distributed worldwide in tropical to sub-tropical 
waters, and is assumed to be part of the cetacean fauna of the tropical 
western North Atlantic (Jefferson et al., 1994; Waring et al., 2007). 
Melon-headed whales are rarely observed by NOAA surveys outside the 
Gulf of Mexico--groups were observed off of Cape Hatteras in 1999 and 
2002--and the rarity of such sightings may be due to a naturally low 
number of groups compared to other cetacean species (Waring et al., 
2007). NMFS has never produced an abundance estimate for this species 
and Roberts et al. (2016) produced a stratified density model on the 
basis of four sightings (Roberts et al., 2015d). The two sightings 
reported by Waring et al. (2007) yield an average group size of 50 
whales; therefore, we authorize take of a single group of a maximum of 
50 whales.
    Spinner Dolphin--Distribution of spinner dolphins in the Atlantic 
is poorly known, but they are thought to occur in deep water along most 
of the U.S. coast south to the West Indies and Venezuela (Waring et 
al., 2014). There have been a handful of sightings in deeper waters off 
the northeast United States and one sighting during a 2011 NOAA 
shipboard survey off North Carolina, as well as stranding records from 
North Carolina south to Florida and Puerto Rico (Waring et al., 2014). 
Roberts et al. (2016) provide a stratified density model on the basis 
of two sightings (Roberts et al., 2015i). Regarding group size, Mullin 
et al. (2004) report a mean of 91.3 in the Gulf of Mexico; May-Collado 
(2005) describe a mean of 100.6 off the Pacific coast of Costa Rica; 
and CETAP (1982) sightings in the Atlantic yield a mean group size of 
42.5 dolphins. As a precaution, we authorize taking a single group with 
a maximum size of 91 dolphins (derived from mean group size reported in 
Mullin et al. 2004).
    Fraser's Dolphin--As was stated for both the pygmy killer whale and 
melon-headed whale, the Fraser's dolphin is distributed worldwide in 
tropical waters, and is assumed to be part of the cetacean fauna of the 
tropical western North Atlantic (Perrin et al., 1994; Waring et al., 
2007). The paucity of sightings of this species may be due to naturally 
low abundance compared to other cetacean species (Waring et al., 2007). 
Despite possibly being more common in the Gulf of Mexico than in other 
parts of its range (Dolar 2009), there were only five reported 
sightings during NOAA surveys from 1992-2009. In the Atlantic, NOAA 
surveys have yielded only two sightings (Roberts et al., 2015f). May-
Collado et al. (2005) reported a single observation of 158 Fraser's 
dolphins off the Pacific coast of Costa Rica, and Waring et al. (2007) 
describe a single observation of 250 Fraser's dolphins in the Atlantic, 
off Cape Hatteras. Therefore, we authorize take of a single group with 
a maximum group size of 204 dolphins (derived from average of May-
Collado et al. 2005 and Waring et al. 2007 sightings data).
    Atlantic White-sided Dolphin--White-sided dolphins are found in 
temperate and sub-polar continental shelf waters of the North Atlantic, 
primarily in the Gulf of Maine and north into Canadian waters (Waring 
et al., 2016). Palka et al. (1997) suggest the existence of stocks in 
the Gulf of Maine, Gulf of St. Lawrence, and Labrador Sea. Stranding 
records from Virginia and North Carolina suggest a southerly winter 
range extent of approximately 35[deg] N (Waring et al., 2016); 
therefore, it is possible that the surveys could encounter white-sided 
dolphins. Roberts et al. (2016) elected to split their study area at 
the north wall of the Gulf Stream, separating the cold northern waters, 
representing probable habitat, from warm southern waters, where white-
sided dolphins are likely not present (Roberts et al., 2015k). Over 600 
observations of Atlantic white-sided dolphins during CETAP (1982) and 
during NMFS surveys provide a mean group size estimate of 47.7 
dolphins, while Weinrich et al. (2001) reported a mean group size of 52 
dolphins. Due to this data, we authorize take of a single group with a 
maximum group size of 48 dolphins.

             Table 8--Numbers of Incidental Take Authorized
------------------------------------------------------------------------
                                           Level B take
                 Species                        **         Level A take
------------------------------------------------------------------------
Humpback whale..........................               3               0
Sei whale...............................               3               0
Fin whale...............................               5               0
Sperm whale.............................             161               0
Kogia spp...............................               9               0
Beaked whales...........................             128               0
Northern bottlenose whale *.............             * 4               0
Rough-toothed dolphin...................              10               0
Common bottlenose dolphin...............             757               0

[[Page 39703]]

 
Clymene dolphin.........................             122               0
Atlantic spotted dolphin................           1,598               0
Pantropical spotted dolphin.............              50               0
Spinner dolphin *.......................            * 91               0
Striped dolphin.........................           1,459               0
Short-beaked common dolphin.............           1,620               0
Fraser's dolphin *......................           * 204               0
Atlantic white-sided dolphin *..........            * 48               0
Risso's dolphin.........................             237               0
Melon-headed whale *....................            * 50               0
Pygmy killer whale *....................             * 6               0
False killer whale *....................             *28               0
Killer whale *..........................             * 7               0
Pilot whales............................             288               0
------------------------------------------------------------------------
* Level B harassment take for rare species represent take of a single
  group.
** Take numbers for non-rare species are the same as those reported in
  Table 7.

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 and impact on 
operations.
    USGS has reviewed mitigation measures employed during seismic 
research surveys authorized by NMFS under previous incidental 
harassment authorizations, as well as recommended best practices in 
Richardson et al. (1995), Pierson et al. (1998), Weir and Dolman 
(2007), Nowacek et al. (2013), Wright (2014), and Wright and Cosentino 
(2015), and has incorporated a suite of mitigation measures into their 
project description based on the above sources.
    To reduce the potential for disturbance from acoustic stimuli 
associated with the activities, USGS will implement the following 
mitigation measures for marine mammals:
    (1) Vessel-based visual mitigation monitoring;
    (2) Establishment of a marine mammal exclusion zone (EZ);
    (3) Shutdown procedures;
    (4) Ramp-up procedures; and
    (5) Vessel strike avoidance measures.
    In addition, USGS will establish a marine mammal buffer zone.
    Protected Species Observer (PSO) observations will take place 
during all daytime airgun operations and nighttime start ups (if 
applicable) of the airguns. If airguns are operating throughout the 
night, observations will begin 30 minutes prior to sunrise. If airguns 
are operating after sunset, observations will continue until 30 minutes 
following sunset. Following a shutdown for any reason, observations 
will occur for at least 30 minutes prior to the planned start of airgun 
operations. Observations will also occur for 30 minutes after airgun 
operations cease for any reason. Observations will also be made during 
daytime periods when the R/V Hugh R. Sharp is underway without seismic 
operations, such as during transits, to allow for comparison of 
sighting rates and behavior with and without airgun operations and 
between acquisition periods. Airgun operations will be suspended when 
marine mammals are observed within, or about to enter, the designated 
Exclusion Zone (EZ) (as described below).
    During seismic operations, three visual PSOs will be based aboard 
the R/V Hugh R. Sharp. PSOs will be appointed by USGS with NMFS 
approval. During the majority of seismic operations (excluding ramp-
up), one PSOs will monitor for marine mammals around the seismic 
vessel. PSO(s) will be on duty in shifts of duration no longer than 
four hours. Other crew will also be instructed to assist in detecting 
marine mammals and in implementing mitigation requirements (if 
practical). Before the start of the seismic survey, the crew will be 
given additional instruction in detecting marine mammals and 
implementing mitigation requirements.
    The R/V Hugh R. Sharp is a suitable platform from which PSOs will 
watch for marine mammals. Standard equipment for marine mammal 
observers will be 7 x 50 reticle binoculars, optical range finders, and 
Big Eye binoculars. At night, night-vision equipment will be available. 
The observers will be in communication with ship's officers on the 
bridge and scientists in the vessel's operations laboratory, so they 
can advise promptly of the need for avoidance maneuvers or seismic 
source shutdown.
    The PSOs must have no tasks other than to conduct observational 
effort, record observational data, and communicate with and instruct 
relevant vessel crew with regard to the presence of marine mammals and 
mitigation requirements. PSO resumes will be

[[Page 39704]]

provided to NMFS for approval. At least one PSO must have a minimum of 
90 days at-sea experience working as a PSO during a seismic survey. One 
``experienced'' visual PSO will be designated as the lead for the 
entire protected species observation team. The lead will serve as 
primary point of contact for the USGS scientist-in-charge or his/her 
designee. 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 will demonstrate good standing and consistently good performance of 
PSO duties.

Exclusion Zone and Buffer Zone

    An EZ is a defined area within which occurrence of a marine mammal 
triggers mitigation action intended to reduce the potential for certain 
outcomes, e.g., auditory injury, disruption of critical behaviors. The 
PSOs will establish a minimum EZ with a 100 m radius from the airgun 
array. The 100 m EZ will be based on radial distance from any element 
of the airgun array (rather than being based on the center of the array 
or around the vessel itself). With certain exceptions (described 
below), if a marine mammal appears within, enters, or appears on a 
course to enter this zone, the acoustic source will be shut down (see 
Shutdown Procedures below).
    The 100 m radial distance of the standard EZ is precautionary in 
the sense that it will be expected to contain sound exceeding injury 
criteria (Level A harassment thresholds) for all marine mammal hearing 
groups (Table 6) while also providing a consistent, reasonably 
observable zone within which PSOs will typically be able to conduct 
effective observational effort.
    Our intent in prescribing a standard EZ distance is to (1) 
encompass zones within which auditory injury could occur on the basis 
of instantaneous exposure; (2) provide additional protection from the 
potential for more severe behavioral reactions (e.g., panic, 
antipredator response) for marine mammals at relatively close range to 
the acoustic source; (3) provide consistency for PSOs, who need to 
monitor and implement the EZ; and (4) define a distance within which 
detection probabilities are reasonably high for most species under 
typical conditions.
    PSOs will also establish and monitor an additional 100 m buffer 
zone beginning from the outside extent of the 100 m EZ. During use of 
the acoustic source, occurrence of marine mammals within the 100 m 
buffer zone will be communicated to the USGS scientist-in-charge or 
his/her designee to prepare for potential shutdown of the acoustic 
source. The 100 m buffer zone is discussed further under Ramp-Up 
Procedures below.

Shutdown Procedures

    If a marine mammal is detected outside the EZ but is likely to 
enter the EZ, the airguns will be shut down before the animal is within 
the EZ. Likewise, if a marine mammal is already within the EZ when 
first detected, the airguns will be shut down immediately.
    Following a shutdown, airgun activity will not resume until the 
marine mammal has cleared the 100 m EZ. The animal will be considered 
to have cleared the 100 m EZ if the following conditions have been met:
     It is visually observed to have departed the 100 m EZ;
     it has not been seen within the 100 m EZ for 15 min in the 
case of small odontocetes; or
     it has not been seen within the 100 m EZ for 30 min in the 
case of mysticetes and large odontocetes, including sperm, pygmy and 
dwarf sperm, beaked whales, and large delphinids.
    This shutdown requirement will be in place for all marine mammals, 
with the exception of small delphinoids under certain circumstances. 
This exception to the shutdown requirement will apply solely to 
specific genera of small dolphins--Tursiops, Steno, Stenella, 
Lagenorhynchus and Delphinus--Instead of shutdown, the acoustic source 
must be powered down to the smallest single element of the array if a 
dolphin of the indicated genera appears within or enters the 100-m 
exclusion zone. If there is uncertainty regarding identification (i.e., 
whether the observed animal(s) belongs to the group described above), 
shutdown must be implemented. Power-down conditions shall be maintained 
until the animal(s) are no longer observed within the exclusion zone, 
following which full-power operations may be resumed without ramp-up. 
PSOs may elect to waive the power-down requirement if the animal(s) 
appear to be voluntarily approaching the vessel for the purpose of 
interacting with the vessel or towed gear, and may use best 
professional judgment in making this decision.
    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 will 
typically be the only marine mammals likely to intentionally approach 
the vessel. As described below, auditory injury is extremely unlikely 
to occur for mid-frequency cetaceans (e.g., delphinids), as this group 
is relatively insensitive to sound produced at the predominant 
frequencies in an airgun pulse while also having a relatively high 
threshold for the onset of auditory injury (i.e., permanent threshold 
shift). Please see ``Potential Effects of the Specified Activity on 
Marine Mammals'' in the Federal Register notice for the proposed IHA 
(83 FR 25268; May 31, 2018) for further discussion of sound metrics and 
thresholds and marine mammal hearing.
    A large body of anecdotal evidence indicates that small delphinoids 
commonly approach vessels and/or towed arrays during active sound 
production for purposes of bow riding, with no apparent effect observed 
in those delphinoids (e.g., Barkaszi et al., 2012). The potential for 
increased shutdowns resulting from such a measure will require the R/V 
Hugh R. Sharp to revisit the missed track line to reacquire data, 
resulting in an overall increase in the total sound energy input to the 
marine environment and an increase in the total duration over which the 
survey is active in a given area. Although other mid-frequency hearing 
specialists (e.g., large delphinoids) are no more likely to incur 
auditory injury than are small delphinoids, they are much less likely 
to approach vessels. Therefore, retaining a shutdown requirement for 
large delphinoids will 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

[[Page 39705]]

than to the auditory impacts. In addition, the required shutdown 
measure may prevent more severe behavioral reactions for any large 
delphnoids in close proximity to the source vessel.
    Shutdown of the acoustic source will also be required upon 
observation beyond the 100 m EZ of any of the following:
     A large whale (i.e., sperm whale or any baleen whale) with 
a calf;
     An aggregation of large whales of any species (i.e., sperm 
whale or any baleen whale) that does not appear to be traveling (e.g., 
feeding, socializing, etc.); or
     A marine mammal species not authorized (i.e., a North 
Atlantic right whale) for take that is approaching or entering the 
Level B harassment zone.
     An authorized marine mammal species that has reached its 
total allotted Level B harassment take that is approaching or entering 
the Level B harassment zone.
    These will be the only four potential situations that will require 
shutdown of the array for marine mammals observed beyond the 100 m EZ.

Ramp-Up Procedures

    Ramp-up of an acoustic source is intended to provide a gradual 
increase in sound levels following a shutdown, enabling animals to move 
away from the source if the signal is sufficiently aversive prior to 
its reaching full intensity. Ramp-up will be required after the array 
is shut down for any reason. Ramp up to the full array will take 20 
minutes, starting with operation of a single airgun and with one 
additional airgun added every 5 minutes.
    At least two PSOs will be required to monitor during ramp-up. 
During ramp up, the PSOs will monitor the 100 m EZ, and if marine 
mammals were observed within or approaching the 100 m EZ, a shutdown 
will be implemented as though the full array were operational. If 
airguns have been shut down due to PSO detection of a marine mammal 
within or approaching the 100 m EZ, ramp-up will not be initiated until 
all marine mammals have cleared the EZ, during the day or night. 
Criteria for clearing the EZ will be as described above.
    Thirty minutes of pre-clearance observation are required prior to 
ramp-up for any shutdown of longer than 30 minutes (i.e., if the array 
were shut down during transit from one line to another). This 30 minute 
pre-clearance period may occur during any vessel activity (i.e., 
transit). If a marine mammal were observed within or approaching the 
100 m EZ or 100 m buffer zone (i.e., total 200 m distance) during this 
pre-clearance period, ramp-up will not be initiated until all marine 
mammals cleared the 100 m EZ or 100 m buffer zone. Criteria for 
clearing the EZ will be as described above. If the airgun array has 
been shut down for reasons other than mitigation (e.g., mechanical 
difficulty) for a period of less than 30 minutes, it may be activated 
again without ramp-up if PSOs have maintained constant visual 
observation and no detections of any marine mammal have occurred within 
the EZ or 100 m buffer zone. Ramp-up will be planned to occur during 
periods of good visibility when possible. However, ramp-up will be 
allowed at night and during poor visibility if the 100 m EZ and 100 m 
buffer zone have been monitored by visual PSOs for 30 minutes prior to 
ramp-up.
    The USGS scientist-in-charge or his/her designee will be required 
to notify a designated PSO of the planned start of ramp-up as agreed-
upon with the lead PSO; the notification time will 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 USGS 
scientist-in-charge or his/her designee must receive confirmation from 
the PSO to proceed. The USGS scientist-in-charge or his/her designee 
must provide information to PSOs documenting that appropriate 
procedures were followed. Following deactivation of the array for 
reasons other than mitigation, the USGS scientist-in-charge or his/her 
designee will be 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 will 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 measures include the following: The USGS scientist-in-charge or 
his/her designee, the vessel operator (The University of Delaware) and 
crew will maintain a vigilant watch for all marine mammals and slow 
down or stop the vessel or alter course to avoid striking any marine 
mammal. A visual observer aboard the vessel will monitor a vessel 
strike avoidance zone around the vessel according to the parameters 
stated below. Visual observers monitoring the vessel strike avoidance 
zone will be either third-party observers or crew members, but crew 
members responsible for these duties will be provided sufficient 
training to distinguish marine mammals from other phenomena. Vessel 
strike avoidance measures will be followed during surveys and while in 
transit.
    The vessel will maintain a minimum separation distance of 100 m 
from large whales (i.e., baleen whales and sperm whales) except for 
North Atlantic right whales. The vessel will maintain a minimum 
separation distance of 500 m from North Atlantic right whales. If a 
large whale is located within 100 m of the vessel or a North Atlantic 
right whale is located within 500 m of the vessel, the vessel will 
reduce speed and shift the engine to neutral, and will not engage the 
engines until the whale has moved outside of the vessel's path and the 
minimum separation distance has been established. If the vessel is 
stationary, the vessel will not engage engines until the whale(s) has 
moved out of the vessel's path and beyond 100 m or 500 m for North 
Atlantic right whale. The vessel will maintain a minimum separation 
distance of 50 m from all other marine mammals (with the exception of 
delphinids of the genera Tursiops, Steno, Stenella, Lagenorhynchus and 
Delphinus that approach the vessel, as described above). If an animal 
is encountered during transit, the vessel will attempt to remain 
parallel to the animal's course, avoiding excessive speed or abrupt 
changes in course. Vessel speeds will be reduced to 10 kn or less when 
mother/calf pairs, pods, or large assemblages of cetaceans (what 
constitues ``large'' will vary depending on species) are observed 
within 500 m of the vessel. Mariners may use professional judgment as 
to when such circumstances warranting additional caution are present.

Actions To Minimize Additional Harm to Live-Stranded (or Milling) 
Marine Mammals

    In the event of a live stranding (or near-shore atypical milling) 
event within 50 km of the survey operations, where the NMFS stranding 
network is engaged in herding or other interventions to return animals 
to the water, the Director of OPR, NMFS (or designee) will advise the 
IHA-holder of the need to implement shutdown procedures for all active 
acoustic sources operating within 50 km of the stranding. Shutdown 
procedures for live stranding or milling marine mammals include the 
following:

[[Page 39706]]

     If at any time, the marine mammal(s) die or are 
euthanized, or if herding/intervention efforts are stopped, the 
Director of OPR, NMFS (or designee) will advise the IHA-holder that the 
shutdown is no longer needed.
     Otherwise, shutdown procedures will remain in effect until 
the Director of OPR, NMFS (or designee) determines and advises the IHA-
holder that all live animals involved have left the area (either of 
their own volition or following an intervention).
     If further observations of the marine mammals indicate the 
potential for re-stranding, additional coordination with the IHA-holder 
will be required to determine what measures are necessary to minimize 
that likelihood (e.g., extending the shutdown or moving operations 
farther away) and to implement those measures as appropriate.
    Shutdown procedures are not related to the investigation of the 
cause of the stranding and their implementation is not intended to 
imply that the specified activity is the cause of the stranding. 
Rather, shutdown procedures are intended to protect marine mammals 
exhibiting indicators of distress by minimizing their exposure to 
possible additional stressors, regardless of the factors that 
contributed to the stranding.
    Based on our evaluation of the applicant's measures, NMFS 
determined that the mitigation measures provide the means effecting the 
least practicable impact on the affected species or stocks and their 
habitat, paying particular attention to rookeries, mating grounds, and 
areas of similar significance.

Monitoring and Reporting

    In order to issue an IHA for an activity, Section 101(a)(5)(D) of 
the MMPA states that NMFS must set forth, requirements pertaining to 
the monitoring and reporting of such taking. The MMPA implementing 
regulations at 50 CFR 216.104(a)(13) indicate that requests for 
authorizations must include the suggested means of accomplishing the 
necessary monitoring and reporting that will result in increased 
knowledge of the species and of the level of taking or impacts on 
populations of marine mammals that are expected to be present in the 
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 will 
contribute to improved understanding of one or more of the following:
     Occurrence of marine mammal species or stocks in the area 
in which take is anticipated (e.g., presence, abundance, distribution, 
density);
     Nature, scope, or context of likely marine mammal exposure 
to potential stressors/impacts (individual or cumulative, acute or 
chronic), through better understanding of: (1) Action or environment 
(e.g., source characterization, propagation, ambient noise); (2) 
affected species (e.g., life history, dive patterns); (3) co-occurrence 
of marine mammal species with the action; or (4) biological or 
behavioral context of exposure (e.g., age, calving or feeding areas);
     Individual marine mammal responses (behavioral or 
physiological) to acoustic stressors (acute, chronic, or cumulative), 
other stressors, or cumulative impacts from multiple stressors;
     How anticipated responses to stressors impact either: (1) 
Long-term fitness and survival of individual marine mammals; or (2) 
populations, species, or stocks;
     Effects on marine mammal habitat (e.g., marine mammal prey 
species, acoustic habitat, or other important physical components of 
marine mammal habitat); and
     Mitigation and monitoring effectiveness.
    USGS 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.
    USGS's monitoring and reporting plan includes the following 
measures:

Vessel-Based Visual Monitoring

    As described above, PSO observations will take place during daytime 
airgun operations and nighttime start-ups (if applicable) of the 
airguns. During seismic operations, three visual PSOs will be based 
aboard the R/V Hugh R. Sharp. PSOs will be appointed by USGS with NMFS 
approval. During the majority of seismic operations (excluding ramp-
up), one PSO will monitor for marine mammals around the seismic vessel. 
PSOs will be on duty in shifts of duration no longer than four hours. 
Other crew will also be instructed to assist in detecting marine 
mammals and in implementing mitigation requirements (if practical). 
During daytime, PSOs will scan the area around the vessel 
systematically with reticle binoculars, Big Eye binoculars, and with 
the naked eye. At night, PSOs will be equipped with night-vision 
equipment.
    PSOs will record data to estimate the numbers of marine mammals 
exposed to various received sound levels and to document apparent 
disturbance reactions or lack thereof. Data will be used to estimate 
numbers of animals potentially taken by harassment. They will also 
provide information needed to order a shutdown of the airguns when a 
marine mammal is within or near the EZ. When a sighting is made, the 
following information about the sighting will be recorded:
    (1) Species, group size, age/size/sex categories (if determinable), 
behavior when first sighted and after initial sighting, heading (if 
consistent), bearing and distance from seismic vessel, sighting cue, 
apparent reaction to the airguns or vessel (e.g., none, avoidance, 
approach, paralleling, etc.), and behavioral pace; and
    (2) Time, location, heading, speed, activity of the vessel, sea 
state, visibility, and sun glare.
    All observations and shutdowns will be recorded in a standardized 
format. Data will be entered into an electronic database. The accuracy 
of the data entry will be verified by computerized data validity checks 
as the data are entered and by subsequent manual checking of the 
database. These procedures will allow initial summaries of data to be 
prepared during and shortly after the field program and will facilitate 
transfer of the data to statistical, graphical, and other programs for 
further processing and archiving. The time, location, heading, speed, 
activity of the vessel, sea state, visibility, and sun glare will also 
be recorded at the start and end of each observation watch, and during 
a watch whenever there is a change in one or more of the variables.
    Results from the vessel-based observations will provide:
    (1) The basis for real-time mitigation (e.g., airgun shutdown);
    (2) Information needed to estimate the number of marine mammals 
potentially taken by harassment, which must be reported to NMFS;
    (3) Data on the occurrence, distribution, and activities of marine 
mammals in the area where the seismic study is conducted;
    (4) Information to compare the distance and distribution of marine 
mammals relative to the source vessel at times with and without seismic 
activity; and
    (5) Data on the behavior and movement patterns of marine mammals 
seen at times with and without seismic activity.

[[Page 39707]]

Reporting Injured or Dead Marine Mammals

    Discovery of Injured or Dead Marine Mammal--In the event that 
personnel involved in the survey activities covered by the 
authorization discover an injured or dead marine mammal, the IHA-holder 
shall report the incident to the Office of Protected Resources (OPR), 
NMFS and to regional stranding coordinators as soon as feasible. The 
report must include the following information:
     Time, date, and location (latitude/longitude) of the first 
discovery (and updated location information if known and applicable);
     Species identification (if known) or description of the 
animal(s) involved;
     Condition of the animal(s) (including carcass condition if 
the animal is dead);
     Observed behaviors of the animal(s), if alive;
     If available, photographs or video footage of the 
animal(s); and
     General circumstances under which the animal was 
discovered.
    Vessel Strike--In the event of a ship strike of a marine mammal by 
any vessel involved in the activities covered by the authorization, the 
IHA-holder shall report the incident to OPR, NMFS and to regional 
stranding coordinators as soon as feasible. The report must include the 
following information:
     Time, date, and location (latitude/longitude) of the 
incident;
     Species identification (if known) or description of the 
animal(s) involved;
     Vessel's speed during and leading up to the incident;
     Vessel's course/heading and what operations were being 
conducted (if applicable);
     Status of all sound sources in use;
     Description of avoidance measures/requirements that were 
in place at the time of the strike and what additional measures were 
taken, if any, to avoid strike;
     Environmental conditions (e.g., wind speed and direction, 
Beaufort sea state, cloud cover, visibility) immediately preceding the 
strike;
     Estimated size and length of animal that was struck;
     Description of the behavior of the marine mammal 
immediately preceding and following the strike;
     If available, description of the presence and behavior of 
any other marine mammals immediately preceding the strike;
     Estimated fate of the animal (e.g., dead, injured but 
alive, injured and moving, blood or tissue observed in the water, 
status unknown, disappeared); and
     To the extent practicable, photographs or video footage of 
the animal(s).
    Additional Information Requests--If NMFS determines that the 
circumstances of any marine mammal stranding found in the vicinity of 
the activity suggest investigation of the association with survey 
activities is warranted (example circumstances noted below), and an 
investigation into the stranding is being pursued, NMFS will submit a 
written request to the IHA-holder indicating that the following initial 
available information must be provided as soon as possible, but no 
later than 7 business days after the request for information.
     Status of all sound source use in the 48 hours preceding 
the estimated time of stranding and within 50 km of the discovery/
notification of the stranding by NMFS; and
     If available, description of the behavior of any marine 
mammal(s) observed preceding (i.e., within 48 hours and 50 km) and 
immediately after the discovery of the stranding.
    Examples of circumstances that could trigger the additional 
information request include, but are not limited to, the following:
     Atypical nearshore milling events of live cetaceans;
     Mass strandings of cetaceans (two or more individuals, not 
including cow/calf pairs);
     Beaked whale strandings;
     Necropsies with findings of pathologies that are unusual 
for the species or area; or
     Stranded animals with findings consistent with blast 
trauma.
    In the event that the investigation is still inconclusive, the 
investigation of the association of the survey activities is still 
warranted, and the investigation is still being pursued, NMFS may 
provide additional information requests, in writing, regarding the 
nature and location of survey operations prior to the time period 
above.

Reporting

    A report will be submitted to NMFS within 90 days after the end of 
the survey. The report will describe the operations that were conducted 
and sightings of marine mammals near the operations. The report will 
provide full documentation of methods, results, and interpretation 
pertaining to all monitoring and will summarize the dates and locations 
of seismic operations, and all marine mammal sightings (dates, times, 
locations, activities, associated seismic survey activities). The 
report will also include estimates of the number and nature of 
exposures that occurred above the harassment threshold based on PSO 
observations, including an estimate of those on the trackline but not 
detected.

Negligible Impact Analysis and Determination

    NMFS has defined negligible impact as an impact resulting from the 
specified activity that cannot be reasonably expected to, and is not 
reasonably likely to, adversely affect the species or stock through 
effects on annual rates of recruitment or survival (50 CFR 216.103). A 
negligible impact finding is based on the lack of likely adverse 
effects on annual rates of recruitment or survival (i.e., population-
level effects). An estimate of the number of takes alone is not enough 
information on which to base an impact determination. In addition to 
considering estimates of the number of marine mammals that might be 
``taken'' through harassment, NMFS considers other factors, such as the 
likely nature of any responses (e.g., intensity, duration), the context 
of any responses (e.g., critical reproductive time or location, 
migration), as well as effects on habitat, and the likely effectiveness 
of the mitigation. We also assess the number, intensity, and context of 
estimated takes by evaluating this information relative to population 
status. Consistent with the 1989 preamble for NMFS' 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).
    NMFS does not anticipate that serious injury or mortality will 
occur as a result of USGS's seismic survey, even in the absence of 
mitigation. Thus, the authorization does not authorize any mortality.
    Potential impacts to marine mammal habitat were discussed 
previously in the Federal Register notice for the proposed IHA (83 FR 
25268; May 31, 2018). Marine mammal habitat may be impacted by elevated 
sound levels, but these impacts will be temporary. Feeding behavior is 
not likely to be significantly impacted, as marine mammals appear to be 
less likely to exhibit behavioral reactions or avoidance responses 
while engaged in feeding activities (Richardson et al., 1995). Prey 
species are mobile and are broadly distributed throughout the project 
area; therefore, marine mammals

[[Page 39708]]

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 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 project 
area during the time of the survey (LaBrecque et al., 2015).
    The acoustic ``footprint'' of the survey will be very small 
relative to the ranges of all marine mammals that will potentially be 
affected. Sound levels will increase in the marine environment in a 
relatively small area surrounding the vessel compared to the range of 
the marine mammals within the survey area. The seismic array will be 
active 24 hours per day throughout the duration of the survey. However, 
the very brief overall duration of the survey (22 days with 19 days of 
airgun operations) will further limit potential impacts that may occur 
as a result of the activity.
    The mitigation measures are expected to reduce the number and/or 
severity of takes by allowing for detection of marine mammals in the 
vicinity of the vessel by visual and acoustic observers, and by 
minimizing the severity of any potential exposures via shutdowns of the 
airgun array.
    Of the marine mammal species that are likely to occur in the 
project area during the survey timeframe, the following species are 
listed as endangered under the ESA; fin, sei, and sperm whales. There 
are currently insufficient data to determine population trends for 
these species (Hayes et al., 2017); however, we are authorizing very 
small numbers of takes for these species (Table 6), relative to their 
population sizes (again, when compared to mean abundance estimates, for 
purposes of comparison only). Therefore, we do not expect population-
level impacts to any of these species. The other marine mammal species 
that may be taken by harassment during USGS's seismic survey are not 
listed as threatened or endangered under the ESA. There is no 
designated critical habitat for any ESA-listed marine mammals within 
the project area; of the non-listed marine mammals for which we 
authorize take, none are considered ``depleted'' or ``strategic'' by 
NMFS under the MMPA, except for pilot whales and false killer whales.
    NMFS concludes that exposures to marine mammal species due to 
USGS's seismic survey will result in only short-term (temporary and 
short in duration) effects to individuals exposed. Marine mammals may 
temporarily avoid the immediate area but are not expected to 
permanently abandon the area. Major shifts in habitat use, 
distribution, or foraging success are not expected. NMFS does not 
anticipate the take estimates to impact annual rates of recruitment or 
survival.
    In summary and as described above, the following factors primarily 
support our determination that the impacts resulting from this activity 
are not expected to adversely affect the species or stock through 
effects on annual rates of recruitment or survival:
     No injury (Level A take), serious injury or mortality is 
anticipated or authorized;
     The anticipated impacts of the activity on marine mammals 
will primarily be temporary behavioral changes due to avoidance of the 
area around the survey vessel. The relatively short duration of the 
survey (22 days with 19 days of airgun operations) will further limit 
the potential impacts of any temporary behavioral changes that will 
occur;
     The availability of alternate areas of similar habitat 
value for marine mammals to temporarily vacate the survey area during 
the survey to avoid exposure to sounds from the activity;
     The 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 survey 
will be temporary and spatially limited; and
     The mitigation measures, including visual and acoustic 
monitoring and shutdowns, are expected to minimize potential impacts to 
marine mammals.
    Based on the analysis contained herein of the likely effects of the 
specified activity on marine mammals and their habitat, and taking into 
consideration the implementation of the monitoring and mitigation 
measures, NMFS finds that the total marine mammal take from the 
activity will have a negligible impact on all affected marine mammal 
species or stocks.

Small Numbers

    As noted above, only small numbers of incidental take may be 
authorized under Section 101(a)(5)(D) of the MMPA for specified 
activities other than military readiness activities. The MMPA does not 
define small numbers and so, in practice, where estimated numbers are 
available, NMFS compares the number of individuals taken to the most 
appropriate estimation of abundance of the relevant species or stock in 
our determination of whether an authorization is limited to small 
numbers of marine mammals. Additionally, other qualitative factors may 
be considered in the analysis, such as the temporal or spatial scale of 
the activities.
    Please see Tables 6 and 7 and the related text for information 
relating to the basis for our small numbers analyses. Table 7 provides 
the numbers of predicted exposures above specified received levels, 
while Table 7 provides the numbers of take authorized. For the northern 
bottlenose whale, Fraser's dolphin, melon-headed whale, false killer 
whale, pygmy killer whale, killer whale, spinner dolphin, and white-
sided dolphin, we authorize take resulting from a single exposure of 
one group of each species or stock, as appropriate (using average group 
size), for each applicant. We believe that a single incident of take of 
one group of any of these species represents take of small numbers for 
that species. Due to the scarcity, broad spatial distributions, and 
habitat preferences of these species relative to the areas where the 
surveys will occur, NMFS concludes that the authorized take of a single 
group of these species likely represent small numbers relative to the 
affected species' overall population sizes. Therefore, based on the 
analyses contained herein of the specified activity, we find that small 
numbers of marine mammals will be taken for each of these eight 
affected species or stocks for the specified activity. We do not 
discuss these eight species further in this small numbers analysis.
    As shown in Table 6, we used mean abundance estimates from Roberts 
(2016) to calculate the percentage of population that is estimated to 
be taken during the activities for non-rare species. The activity is 
expected to impact a very small percentage of all marine mammal 
populations. As presented in Table 6, take of all 21 marine mammal 
species authorized for take is less than three percent of the abundance 
estimate.
    Based on the analysis contained herein of the activity (including 
the mitigation and monitoring measures) and the anticipated take of 
marine mammals, NMFS finds that small numbers of marine mammals will be 
taken relative to the population size of the affected species or 
stocks.

[[Page 39709]]

Unmitigable Adverse Impact Analysis and Determination

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

Endangered Species Act (ESA)

    Section 7(a)(2) of the Endangered Species Act of 1973 (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 NMFS' ESA Interagency 
Cooperation Division, whenever we authorize take for endangered or 
threatened species.
    NMFS's ESA Interagency Cooperation Division issued a Biological 
Opinion on August 6, 2018 to NMFS Office of Protected Resources which 
concluded that the USGS's MATRIX survey is not likely to jeopardize the 
continued existence of the sei whale, fin whale, sperm whale, and north 
Atlantic right whale or adversely modify critical habitat.

National Environmental Policy Act

    To comply with the National Environmental Policy Act of 1969 (NEPA; 
42 U.S.C. 4321 et seq.) and NOAA Administrative Order (NAO) 216-6A, 
NMFS must review our proposed action (i.e., the issuance of an 
incidental harassment authorization) with respect to potential impacts 
on the human environment. Accordingly, NMFS prepared an Environmental 
Assessment (EA) to consider the environmental impacts associated with 
the issuance of the IHA to USGS. We reviewed all comments submitted in 
response to the Federal Register notice for the proposed IHA (83 FR 
25268; May 31, 2018) prior to concluding our NEPA process and deciding 
whether or not to issue a Finding of No Significant Impact (FONSI). 
NMFS concluded that issuance of an IHA to USGS will not significantly 
affect the quality of the human environment and prepared and issued a 
FONSI in accordance with NEPA and NAO 216-6A. NMFS's EA and FONSI for 
this activity are available on our website at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-research-and-other-activities.

Authorization

    As a result of these determinations, we have issued an IHA to USGS 
for conducting the described seismic survey activities from August 1, 
2018 through July 31, 2019 provided the previously described 
mitigation, monitoring, and reporting requirements are incorporated.

    Dated: August 7, 2018.
Donna S. Wieting,
Director, Office of Protected Resources, National Marine Fisheries 
Service.
[FR Doc. 2018-17170 Filed 8-9-18; 8:45 am]
 BILLING CODE 3510-22-P