[Federal Register Volume 83, Number 235 (Friday, December 7, 2018)]
[Notices]
[Pages 63268-63381]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2018-26460]



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Vol. 83

Friday,

No. 235

December 7, 2018

Part III





 Department of Commerce





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National Oceanic and Atmospheric Administration





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Takes of Marine Mammals Incidental to Specified Activities; Taking 
Marine Mammals Incidental to Geophysical Surveys in the Atlantic Ocean; 
Notice

  Federal Register / Vol. 83 , No. 235 / Friday, December 7, 2018 / 
Notices  

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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

RIN 0648-XE283


Takes of Marine Mammals Incidental to Specified Activities; 
Taking Marine Mammals Incidental to Geophysical Surveys in the Atlantic 
Ocean

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

ACTION: Notice; issuance of five incidental harassment authorizations.

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SUMMARY: In accordance with the regulations implementing the Marine 
Mammal Protection Act (MMPA) as amended, notification is hereby given 
that we have issued incidental harassment authorizations (IHA) to five 
separate applicants to incidentally harass marine mammals during 
geophysical survey activities in the Atlantic Ocean.

DATES: These authorizations are effective for one year from the date of 
effectiveness.

FOR FURTHER INFORMATION CONTACT: Ben Laws, Office of Protected 
Resources, NMFS, (301) 427-8401.

SUPPLEMENTARY INFORMATION:

Availability

    Electronic copies of the applications and supporting documents, as 
well as a list of the references cited in this document, may be 
obtained online at: www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-atlantic. In case of problems accessing these documents, please call 
the contact listed above.

Background

    Section 101(a)(5)(D) of the MMPA (16 U.S.C. 1361 et seq.) directs 
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 specific geographic region if 
certain findings are made and 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, or 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 Requests

    In 2014, the Bureau of Ocean Energy Management (BOEM) produced a 
Programmatic Environmental Impact Statement (PEIS) to evaluate 
potential significant environmental effects of geological and 
geophysical (G&G) activities on the Mid- and South Atlantic Outer 
Continental Shelf (OCS), pursuant to requirements of the National 
Environmental Policy Act (NEPA). BOEM's PEIS and associated Record of 
Decision are available online at: www.boem.gov/Atlantic-G-G-PEIS/. G&G 
activities include geophysical surveys in support of hydrocarbon 
exploration, as are planned by the five IHA applicants discussed 
herein.
    In 2014-15, we received multiple separate requests for 
authorization for take of marine mammals incidental to geophysical 
surveys in support of hydrocarbon exploration in the Atlantic Ocean. 
The applicants are companies that provide services, such as geophysical 
data acquisition, to the oil and gas industry. Upon review of these 
requests, we submitted questions, comments, and requests for additional 
information to the individual applicant companies. As a result of these 
interactions, the applicant companies provided revised versions of the 
applications that we determined were adequate and complete. Adequate 
and complete applications were received from ION GeoVentures (ION) on 
June 24, 2015, Spectrum Geo Inc. (Spectrum) on July 6, 2015, and from 
TGS-NOPEC Geophysical Company (TGS) on July 21, 2015.
    We subsequently posted these applications for public review and 
sought public input (80 FR 45195; July 29, 2015). The comments and 
information received during this public review period informed 
development of the proposed IHAs (82 FR 26244; June 6, 2017), and all 
letters received are available online at www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-atlantic. Following conclusion of this opportunity for public 
review, we received revised applications from Spectrum on September 18, 
2015, and from TGS on February 10, 2016. We received additional 
information from ION on February 29, 2016. We also received adequate 
and complete applications from two additional applicants: WesternGeco, 
LLC (Western) on February 17, 2016, and CGG on May 26, 2016. Full 
details regarding these timelines were described in our Federal 
Register Notice of Proposed IHAs (82 FR 26244; June 6, 2017).
    On June 26, 2018, Spectrum notified NMFS of a modification to their 
survey plan. Spectrum's letter and related information is available 
online, as is their preceding adequate and complete application. The 
descriptions and analyses contained herein were complete at the time we 
received notification of the modification. Therefore, we present those 
descriptions and analyses, including those related to Spectrum's 
request (as detailed in their 2015 application), intact as originally 
developed. However, we provide detail regarding Spectrum's modified 
survey plan, our evaluation of the modification to the specified 
activity, and our finding that the determinations made in regard to 
Spectrum's previously proposed specified activity remain appropriate 
and valid in a standalone section entitled ``Spectrum Survey Plan 
Modification'' at the end of this notice.
    All issued authorizations are valid for the statutory maximum of 
one year. All applicants plan to conduct two-dimensional (2D) marine 
seismic surveys using airgun arrays. Generally speaking, these surveys 
may occur within the U.S. Exclusive Economic Zone (EEZ) (i.e., to 200 
nautical miles (nmi)) from Delaware to approximately Cape Canaveral, 
Florida, and corresponding with BOEM's Mid- and South Atlantic OCS 
planning areas, as well as additional waters out to 350 nmi from shore. 
Please see the applications for specific details of survey design. The 
use of airgun arrays is expected to

[[Page 63269]]

produce underwater sound at levels that have the potential to result in 
harassment of marine mammals. Multiple cetacean species with the 
expected potential to be present during all or a portion of the planned 
surveys are described below.
    Because the specified activity, specific geographic region, and 
planned dates of activity are substantially similar for the five 
separate requests for authorization, we have determined it appropriate 
to provide a joint notice for issuance of the five authorizations. 
However, while we provide relevant information together, we consider 
the potential impacts of the specified activities independently and 
make determinations specific to each request for authorization, as 
required by the MMPA.

Description of the Specified Activities

    In this section, we provide a generalized discussion that is 
broadly applicable to all five requests for authorization, with 
project-specific portions indicated.

Overview

    The five applicants plan to conduct deep penetration seismic 
surveys using airgun arrays as an acoustic source. Seismic surveys are 
one method of obtaining geophysical data used to characterize the 
subsurface structure, in this case in support of hydrocarbon 
exploration. The planned surveys are 2D surveys, designed to acquire 
data over large areas in order to screen for potential hydrocarbon 
prospectivity. To contrast, three-dimensional surveys may use similar 
acoustic sources but are designed to cover smaller areas with greater 
resolution (e.g., with closer survey line spacing). A deep penetration 
survey uses an acoustic source suited to provide data on geological 
formations that may be thousands of meters (m) beneath the seafloor, as 
compared with a survey that may be intended to evaluate shallow 
subsurface formations or the seafloor itself (e.g., for hazards).
    An airgun is a device used to emit acoustic energy pulses into the 
seafloor, and generally consists of a steel cylinder that is charged 
with high-pressure air. The firing pressure of an array is typically 
2,000 pounds per square inch (psi). Release of the compressed air into 
the water column generates a signal that reflects (or refracts) off of 
the seafloor and/or subsurface layers having acoustic impedance 
contrast. When fired, a brief (~0.1 second (s)) pulse of sound is 
emitted by all airguns nearly simultaneously. The airguns do not fire 
during the intervening periods, with the array typically fired on a 
fixed distance (or shot point) interval. This interval may vary 
depending on survey objectives, but a typical interval for a 2D survey 
in relatively deep water might be 25 m (approximately every 10 s, 
depending on vessel speed). Vessel speed when towing gear is typically 
4-5 knots (kn). The return signal is recorded by a listening device and 
later analyzed with computer interpretation and mapping systems used to 
depict the subsurface. In this case, towed streamers contain 
hydrophones that would record the return signal.
    Individual airguns are available in different volumetric sizes, and 
for deep penetration seismic surveys are towed in arrays (i.e., a 
certain number of airguns of varying sizes in a certain arrangement) 
designed according to a given company's method of data acquisition, 
seismic target, and data processing capabilities. A typical large 
airgun array, as was considered in BOEM's PEIS (BOEM, 2014a), may have 
a total volume of approximately 5,400 cubic inches (in\3\). The 
notional array modeled by BOEM consists of 18 airguns in three 
identical strings of six airguns each, with individual airguns ranging 
in volume from 105-660 in\3\. Sound levels for airgun arrays are 
typically modeled or measured at some distance from the source and a 
nominal source level then back-calculated. Because these arrays 
constitute a distributed acoustic source rather than a single point 
source (i.e., the ``source'' is actually comprised of multiple sources 
with some pre-determined spatial arrangement), the highest sound levels 
measurable at any location in the water will be less than the nominal 
source level. A common analogy is to an array of light bulbs; at 
sufficient distance the array will appear to be a single point source 
of light but individual sources, each with less intensity than that of 
the whole, may be discerned at closer distances. In addition, the 
effective source level for sound propagating in near-horizontal 
directions (i.e., directions likely to impact most marine mammals in 
the vicinity of an array) is likely to be substantially lower than the 
nominal source level applicable to downward propagation because of the 
directional nature of the sound from the airgun array. The horizontal 
propagation of sound is reduced by noise cancellation effects created 
when sound from neighboring airguns on the same horizontal plane 
partially cancel each other out.
    Survey protocols generally involve a predetermined set of survey, 
or track, lines. The seismic acquisition vessel (source vessel) will 
travel down a linear track for some distance until a line of data is 
acquired, then turn and acquire data on a different track. In addition 
to the line over which data acquisition is desired, full-power 
operation may include run-in and run-out. Run-in is approximately 1 
kilometer (km) of full-power source operation before starting a new 
line to ensure equipment is functioning properly, and run-out is 
additional full-power operation beyond the conclusion of a trackline 
(typically half the distance of the acquisition streamer behind the 
source vessel) to ensure that all data along the trackline are 
collected by the streamer. Line turns typically require two to three 
hours due to the long, trailing streamers (approximately 10 km). 
Spacing and length of tracks vary by survey. Survey operations often 
involve the source vessel, supported by a chase vessel. Chase vessels 
typically support the source vessel by protecting the hydrophone 
streamer from damage (e.g., from other vessels) and otherwise lending 
logistical support (e.g., returning to port for fuel, supplies, or any 
necessary personnel transfers). Chase vessels do not deploy acoustic 
sources for data acquisition purposes; the only potential effects of 
the chase vessels are those associated with normal vessel operations.

Dates and Duration

    All issued IHAs are valid for the statutory maximum of one year 
from the date of effectiveness. The IHAs are effective upon written 
notification from the applicant to NMFS, but not beginning later than 
one year from the date of issuance or extending beyond two years from 
the date of issuance. However, the expected temporal extent of survey 
activity varies by company and may be subject to unpredictability due 
to inclement weather days, equipment maintenance and/or repair, transit 
to and from ports to survey locations, and other contingencies. 
Spectrum originally planned a 6-month data acquisition program 
(February through July), consisting of an expected 165 days of seismic 
operations. This plan has been modified and now consists of an 
estimated 108 days of operations. Please see ``Spectrum Survey Plan 
Modification'' for further information. TGS plans a full year data 
acquisition program, with an estimated 308 days of seismic operations. 
ION plans a six-month data acquisition program (July through December), 
with an estimated 70 days of seismic data collection. Western plans a 
full year data acquisition program, with an estimated 208 days of 
seismic operations. CGG plans a six-month data acquisition program 
(July through

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December), with an estimated 155 days of seismic operations. Seismic 
operations typically occur 24 hours per day.

Specific Geographic Region

    The planned survey activities would occur off the Atlantic coast of 
the United States, within BOEM's Mid-Atlantic and South Atlantic OCS 
planning areas (i.e., from Delaware to Cape Canaveral, FL), and out to 
350 nmi (648 km) (see Figure 1, reproduced from BOEM, 2014a). The 
seaward limit of the region is based on the maximum constraint line for 
the extended continental shelf (ECS) under the United Nations 
Convention on the Law of the Sea. Until such time as an ECS is 
established by the United States, the region between the U.S. EEZ 
boundary and the ECS maximum constraint line (i.e., 200-350 nmi from 
shore) is part of the global commons, and BOEM determined it 
appropriate to include this area within the area of interest for 
geophysical survey activity.
    The specific survey areas differ within this region; please see 
maps provided in the individual applications (Spectrum: Figure 1; 
Western: Figures 1-1 to 1-4; TGS: Figures 1-1 to 1-4; ION: Figure 1; 
CGG: Figure 3) (however, please see ``Spectrum Survey Plan 
Modification'' for further information). The specific geographic region 
has not changed compared with what was described in our Notice of 
Proposed IHAs (82 FR 26244; June 6, 2017), nor has substantive new 
information regarding the region become available. Therefore, we do not 
reprint that discussion here; for additional detail regarding the 
specific geographic region, please see our Notice of Proposed IHAs.
BILLING CODE 3510-22-P

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[GRAPHIC] [TIFF OMITTED] TN07DE18.000

BILLING CODE 3510-22-P

Detailed Description of Activities

    Survey descriptions, as summarized from specific applications, are 
provided here. Please see Table 1 for a summary of airgun array 
characteristics. With the exception of Spectrum, the planned surveys 
have not changed from those described in our Notice of Proposed IHAs 
(82 FR 26244; June 6, 2017) Please see ``Spectrum Survey Plan 
Modification'' for further information. For full detail, please see the 
individual IHA applications and our Notice of Proposed IHAs. Note that 
all applicants expect there to be limited additional operations 
associated with equipment testing, startup, line changes, and repeat 
coverage of any areas where initial data quality is sub-standard. 
Therefore, there

[[Page 63272]]

could be some small amount of use of the acoustic source not accounted 
for in the total estimated line-km for each survey; however, this 
activity is difficult to quantify in advance and would represent an 
insignificant increase in effort.
    ION--ION's survey is planned to occur from Delaware to northern 
Florida (~38.5[deg] N to ~27.9[deg] N) (see Figure 1 of ION's 
application), and consists of ~13,062 km of survey line. The acoustic 
source planned for deployment is a 36-airgun array with a total volume 
of 6,420 in\3\. The array would consist of airguns ranging in volume 
from 40 in\3\ to 380 in\3\. The airguns would be configured as four 
identical linear arrays or ``strings'' (see Figure 3 of ION's 
application). The four airgun strings would be towed at 10-m depth, and 
would fire every 50 m or 20-24 s, depending on exact vessel speed. ION 
provided modeling results for their array, including notional source 
signatures, 1/3-octave band source levels as a function of azimuth 
angle, and received sound levels as a function of distance and 
direction at 16 representative sites in the survey area. For more 
detail, please see Figures 4-6 and Appendix A of ION's application.
    Spectrum--Spectrum's survey was originally planned to occur from 
Delaware to northern Florida (see Figure 1 of Spectrum's application), 
consisting of ~21,635 km of survey line. This plan has been modified 
and now consists of ~13,766 km of operations. Please see ``Spectrum 
Survey Plan Modification'' for further information). The acoustic 
source planned for deployment is a 32-airgun array with a total volume 
of 4,920 in\3\. The array would consist of airguns ranging in volume 
from 50 in\3\ to 250 in\3\. The airguns would be configured as four 
subarrays, each with eight to ten airguns (see Figure 2 in Appendix A 
of Spectrum's application). The four airgun strings would be towed at 6 
to 10-m depth, and would fire every 25 m or 10 s, depending on exact 
vessel speed. Spectrum provided modeling results for their array, 
including notional source signatures, 1/3-octave band source levels as 
a function of azimuth angle, and received sound levels as a function of 
distance and direction at 16 representative sites in the survey area. 
For more detail, please see Appendix A of Spectrum's application.
    As stated above, Spectrum notified NMFS on June 26, 2018, of a 
modification to their survey plan. Please see ``Spectrum Survey Plan 
Modification'' for further information.
    TGS--TGS's survey is planned to occur from Delaware to northern 
Florida (see Figure 1-1 of TGS's application), and consists of ~58,300 
km of survey line. The survey plan consists of two contiguous survey 
grids with differently spaced lines (see Figures 1-1 to 1-4 of TGS's 
application), and would involve use of two source vessels operating 
independently of one another at a minimum of 100 km separation 
distance. The acoustic sources planned for deployment are 40-airgun 
arrays with a total volume of 4,808 in\3\. The array would consist of 
airguns ranging in volume from 22 in\3\ to 250 in\3\. The airguns would 
be configured as four identical strings (see Figure 3 in Appendix B of 
TGS's application). The four airgun strings would be towed at 7-m 
depth, and would fire every 25 m or 10 s, depending on exact vessel 
speed. More detail regarding TGS's acoustic source and modeling related 
to TGS's application is provided in Appendix B of TGS's application.
    Western--Western's survey is planned to occur from Maryland to 
northern Florida (see Figure 1-1 of Western's application), and 
consists of ~27,330 km of survey line. The survey plan consists of a 
survey grid with differently spaced lines (see Figures 1-1 to 1-4 of 
Western's application). The acoustic source planned for deployment is a 
24-airgun array with a total volume of 5,085 in\3\. The airguns would 
be configured as three identical strings. The three airgun strings 
would be towed at 10-m depth, and would fire every 37.5 m 
(approximately every 16 s, depending on vessel speed). More detail 
regarding Western's acoustic source and modeling related to Western's 
application is provided in Appendix B of Western's application.
    CGG--CGG's survey is planned to occur from Virginia to Georgia (see 
Figure 3 of CGG's application), and consists of ~28,670 km of survey 
line. The acoustic source planned for deployment is a 36-airgun array 
with a total volume of 5,400 in\3\. The array would consist of airguns 
ranging in volume from 40 in\3\ to 380 in\3\. The airguns would be 
configured as four identical strings (see Figure 2 of CGG's 
application). The four airgun strings would be towed at 7-m depth, and 
would fire every 25 m or 10 s, depending on exact vessel speed. More 
detail regarding CGG's acoustic source and modeling related to CGG's 
application is provided in CGG's application.

                                                    Table 1--Survey and Airgun Array Characteristics
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                                        Total        Total                                Nominal source output (downward) \1\      Shot
              Company                  planned       volume     Number of    Number of  ---------------------------------------   interval    Tow depth
                                      survey km     (in\3\)        guns       strings        0-pk        pk-pk         rms          (m)          (m)
--------------------------------------------------------------------------------------------------------------------------------------------------------
ION................................       13,062        6,420           36            4          257          263      \4\ 247           50           10
Spectrum...........................       13,766        4,920           32            4          266          272          243           25         6-10
TGS................................       58,300        4,808           40            4          255        (\3\)          240           25            7
Western............................       27,330        5,085           24            3        (\3\)          262          235         37.5           10
CGG................................       28,670        5,400           36            4        (\3\)          259      3 4 243           25            7
BOEM \2\...........................          n/a        5,400           18            3          247        (\3\)          233          n/a          6.5
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\1\ See ``Description of Active Acoustic Sound Sources,'' later in this document, for discussion of these concepts.
\2\ Notional array characteristics modeled and source characterization outputs from BOEM's PEIS (2014a) provided for comparison.
\3\ Values not given; however, SPL (pk-pk) is usually considered to be approximately 6 dB higher than SPL (0-pk) (Greene, 1997).
\4\ Value decreased from modeled 0-pk value by minimum 10 dB (Greene, 1997).

Comments and Responses

    We published a Notice of Proposed IHAs in the Federal Register on 
June 6, 2017 (82 FR 26244), beginning a 30-day comment period. In that 
notice, we requested public input on the requests for authorization 
described therein, our analyses, the proposed authorizations, and any 
other aspect of the Notice of Proposed IHAs for the five separate 
specified geophysical survey activities, and requested that interested 
persons submit relevant information, suggestions, and comments. We 
further specified that, in accordance with the requirements of the 
MMPA, we would only consider comments that were relevant to marine 
mammal species that occur in U.S. waters of the Mid- and South Atlantic 
and the potential effects of the specified geophysical survey 
activities on those species and their habitat. We also noted that 
comments

[[Page 63273]]

indicating general support for or opposition to hydrocarbon exploration 
or any comments relating to hydrocarbon development (e.g., leasing, 
drilling) were not relevant to the proposed actions and would not be 
considered. We requested that comments indicate whether they were 
general to all of the proposed authorizations or specific to one or 
more of the five separate proposed authorizations, and that comments 
should be supported by data or literature citations as appropriate. 
Following requests to extend the public comment period, we determined 
it appropriate to do so by an additional 15 days (82 FR 31048; July 5, 
2017). Including the 15-day extension, the public comment period 
concluded on July 21, 2017. Comments received after the close of the 
comment period were not considered.
    During the 45-day comment period, we received 117,294 total comment 
letters. Of this total, we determined that approximately 3,196 comment 
letters represented unique submissions, including 73 letters from 
various organizations or individuals acting in an official capacity 
(e.g., non-governmental organizations, representatives and members of 
the oil and gas industry, state and local government, members of 
Congress, members of academia) and 3,103 unique submissions from 
private citizens. We note that the 73 letters represent approximately 
330 organizations or individuals, as many letters included multiple co-
signers. The remaining approximately 114,118 comment letters followed 
one of 20 different generic template formats, in which respondents 
provided comments that were identical or substantively the same. We 
consider each of the 20 different templates to represent a single 
unique submission that is included in the value cited above (3,196). 
Separately, we received 15 petitions, with a total of 99,423 
signatures. Of these, one petition (595 signatures) expressed support 
for issuance of the proposed IHAs, while the remainder expressed 
opposition to issuance of the proposed IHAs or, more generally, to oil 
and gas exploration and/or development in the U.S. Atlantic Ocean.
    NMFS has reviewed all public comments received on the proposed 
issuance of the five IHAs. All relevant comments and our responses are 
described below. Comments indicating general support for or opposition 
to hydrocarbon exploration but not containing relevant recommendations 
or information are not addressed here. Similarly, any comments relating 
to hydrocarbon development (e.g., leasing, drilling)--including 
numerous comments received that expressed concern regarding the risks 
of oil spills or of potential future industrialization on the U.S. 
Atlantic coast--are not relevant to the proposed actions and therefore 
were not considered and are not addressed here. We also provide no 
response to specific comments that addressed species or statutes not 
relevant to our proposed actions under section 101(a)(5)(D) of the MMPA 
(e.g., comments related to sea turtles), nor do we respond to comments 
more appropriately directed at BOEM pursuant to their authority under 
the Outer Continental Shelf Lands Act (OCSLA) to permit the planned 
activities. For those comments germane to the proposed IHAs, we outline 
our comment responses by major categories. Recurring comments are noted 
below as having been submitted by ``several'' or ``many'' commenters to 
avoid repetition. The 73 letters from various organizations or 
individuals acting in an official capacity, and representatives of each 
of the 20 form letter templates, are available online at: 
www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-atlantic. Remaining comments 
are part of our administrative record for these actions but are not 
available online.

General Comments

    A large majority of commenters, including all of those following 
one of the 20 templates, expressed general opposition towards 
geophysical airgun surveys in the U.S. Atlantic Ocean. We reiterate 
here that NMFS's proposed actions concern only the authorization of 
marine mammal take incidental to the planned surveys--jurisdiction 
concerning decisions to allow the surveys rests solely with BOEM, 
pursuant to their authority under the OCSLA. Further, NMFS does not 
have discretion regarding issuance of requested incidental take 
authorizations pursuant to the MMPA, assuming (1) the total taking 
associated with a specified activity will have a negligible impact on 
the affected species or stock(s); (2) the total taking associated with 
a specified activity will not have an unmitigable adverse impact on the 
availability of the species or stock(s) for subsistence uses (not 
relevant here); (3) the total taking associated with a specified 
activity is small numbers of marine mammals of any species or stock; 
and (4) appropriate mitigation, monitoring, and reporting of such 
takings are set forth, including mitigation measures sufficient to meet 
the standard of least practicable adverse impact on the affected 
species or stocks. A large volume of the comments received request that 
NMFS not issue any of the IHAs and/or express disdain for NMFS's 
proposal to issue the requested IHAs, but without providing information 
relevant to NMFS's decisions. These comments appear to indicate a lack 
of understanding of the MMPA's requirement that NMFS shall issue 
requested authorizations when the above listed conditions are met; 
therefore, these comments were not considered.
    In general, commenters described the close linkages between their 
local and state economies to a healthy ocean, contending that the 
planned surveys could have substantial impacts on, for example, 
commercial and recreational fishing, wildlife viewing, outdoor 
recreation, and businesses dependent on these activities. Commenters 
suggested that NMFS should undertake analyses unrelated to the proposed 
actions (i.e., issuance of requested IHAs), such as a cost-benefit 
analysis of hydrocarbon exploration and development compared to the 
economic benefits of coastal tourism and healthy fisheries. Many 
commenters also noted that over 120 municipalities and cities and 1,200 
elected officials on the Atlantic coast have passed resolutions or 
otherwise formally opposed hydrocarbon exploration and/or development 
in the region. We also received comments expressing general opposition 
to oil and gas exploration activity from the Business Alliance for 
Protecting the Atlantic Coast, which stated that the comments were 
submitted on behalf of 41,000 businesses and 500,000 commercial fishing 
families. While NMFS recognizes the overwhelming opposition expressed 
by the public to oil and gas exploration and/or development in the U.S. 
Atlantic Ocean that it has received, we remain appropriately focused on 
consideration of the best available scientific information in support 
of our analyses pursuant to the MMPA, specific to the five IHAs 
considered herein.
    Multiple commenters focused on specific, rather than general, 
issues that are not germane to our consideration of requested action 
under the MMPA. For example, the Northwest Atlantic Marine Alliance 
(NAMA) and other groups provided comments related to potential impacts 
on commercial fisheries, and the New Jersey Council of Diving Clubs 
expressed concern regarding potential impacts of the planned surveys on 
recreational divers. Recommendations were provided concerning 
mitigating potential impacts. We reiterate that NMFS's proposed 
action--the issuance

[[Page 63274]]

of IHAs authorizing incidental take of marine mammals--necessarily 
results in impacts only to marine mammals and marine mammal habitat. 
Effects of the surveys more broadly are the purview of BOEM, which has 
jurisdiction under OCSLA for permitting the actual surveys, as opposed 
to authorizing take of marine mammals incidental to a permitted survey. 
Therefore, we do not address comments such as these.
    Multiple groups stated that NMFS should consider impacts and 
protection for other species in the action area, such as Atlantic 
sturgeon, other fish species, invertebrates, plankton, and sea turtles. 
Some of these comments specifically referenced the importance of the 
area offshore Cape Hatteras as home to a diverse assemblage of non-
marine mammal species, including sharks, turtles, seabirds, and other 
fish species. The NAMA provided comments relating to Essential Fish 
Habitat (EFH) (as designated pursuant to the Magnuson Stevens Fishery 
Conservation and Management Act (MSA), as amended by the Sustainable 
Fisheries Act of 1996 (Pub. L. 104-267)), including concerns regarding 
effects to EFH resulting from the planned surveys. Because NMFS's 
proposed action is limited to the authorization of marine mammal take 
incidental to the planned surveys, effects of the surveys on aspects of 
the marine environment other than marine mammals and their habitat are 
not relevant to NMFS's analyses under the MMPA. Pursuant to guidance 
from NMFS's Office of Habitat Conservation concerning EFH and MMPA 
incidental take authorizations, we have determined that the issuance of 
these IHAs will not result in adverse impacts to EFH, and further, that 
issuance of these IHAs does not require separate consultation per 
section 305(B)(2) of the MSA. We do not further address potential 
impacts to EFH.
    The MMPA does require that we evaluate potential effects to marine 
mammal habitat, which includes prey species (e.g., zooplankton, fish, 
squid). However, consideration of potential effects to taxa other than 
marine mammals and their prey, or consideration of effects to potential 
prey species in a context other than the import of such effects on 
marine mammals, is not relevant to our action under the MMPA. We have 
appropriately considered effects to marine mammal habitat. Separately, 
BOEM evaluated effects to all relevant aspects of the human environment 
(including marine mammals and other taxa) through the analysis 
presented in their PEIS (available online at: www.boem.gov/Atlantic-G-G-PEIS/), and effects to all potentially affected species that are 
listed under the Endangered Species Act (ESA) and any critical habitat 
designated for those species were addressed through consultation 
between BOEM and NMFS pursuant to section 7 of the ESA. That Biological 
Opinion, which evaluated both BOEM's (issuing permits for the five 
surveys) and NMFS's (issuing IHAs associated with the five permitted 
surveys) proposed actions, is available online at: 
www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-atlantic. We do not further 
address taxa other than marine mammals and marine mammal prey.

Marine Mammal Impacts

    Comment: Many commenters expressed concern regarding the perceived 
lack of information regarding the affected marine mammal stocks and the 
impacts of the surveys on marine mammal individuals and populations and 
their habitat (direct and indirect; short- and long-term).
    Response: NMFS acknowledges that, while there is a growing body of 
literature on the affected marine mammal stocks and regarding the 
impacts of noise on individual marine mammals, data gaps do remain, 
particularly with regard to potential population-level impacts and 
cumulative impacts. However, NMFS must use the best available 
scientific information in analyses supporting its determinations 
pursuant to the MMPA, and has done so here. While NMFS does not take 
lightly the potential effects of surveys on marine mammal populations, 
these surveys, with the robust suite of required mitigation and 
monitoring, are expected to have a negligible impact on the affected 
species and stocks.
    Comment: Many commenters expressed general concern regarding 
impacts to both individual marine mammals and potential population-
level harm, including impacts to important behaviors and chronic stress 
stemming from acoustic disturbance. More specifically, this included: 
Potential displacement from preferred feeding, breeding, and migratory 
habitats, which could lead to long-term and large-scale habitat 
avoidance or abandonment; impacts to mating, vocalizing, and other key 
marine mammal behaviors; communication interference between cow-calf 
pairs, which could lead to stranding increases and juvenile deaths; 
hearing loss hindering recruitment and marine mammals' ability to 
locate mates and find food.
    Response: NMFS has carefully reviewed the best available scientific 
information in assessing impacts to marine mammals, and recognizes that 
the surveys have the potential to impact marine mammals through 
threshold shifts, behavioral effects, stress responses, and auditory 
masking. However, NMFS has determined that the nature of such 
potentially transitory exposure--any given location will be exposed to 
survey noise only relatively briefly and infrequently--means that the 
potential significance of the authorized taking, including potential 
long-term avoidance, is limited. NMFS has also prescribed a robust 
suite of mitigation measures, such as time-area restrictions and 
extended distance shutdowns for certain species, that are expected to 
further reduce the duration and intensity of acoustic exposure, while 
limiting the potential severity of any possible behavioral disruption.
    Comment: Many commenters described impacts to ``millions of marine 
mammals,'' expressing concern that NMFS would allow such a level of 
impacts, or stating concern that NMFS would allow killing of marine 
mammals. Similarly, many commenters refer to taking or killing 
``138,000 marine mammals.''
    Response: Many of these comments were written with reference to the 
acoustic exposure analysis provided in BOEM's PEIS, which is not 
directly related to the specific surveys that are the subject of NMFS's 
analysis. In fact, the more specific figure commonly cited (i.e., 
138,000) represents the number of incidents of Level A harassment 
estimated by BOEM in their analysis using now-outdated guidance (i.e., 
180-dB root mean square (rms) with no consideration of frequency 
sensitivity) that the best available science indicates does not reflect 
when Level A harassment should be expected to occur. Certain non-
governmental organizations have incorrectly suggested the information 
represents animals killed. In addition, BOEM's programmatic analysis 
was based on a vastly greater amount of survey activity occurring per 
year over a period of nine years, versus the five surveys considered 
herein. Regardless, NMFS cannot issue the authorizations unless the 
total taking expected to occur as a result of each specified activity 
is determined to result in a negligible impact to the affected species 
or stocks. The best available science indicates that Level B 
harassment, or disruption of behavioral patterns, is likely to occur, 
and that a limited amount of auditory injury, or permanent threshold 
shift (PTS) (Level A harassment) may occur for a few

[[Page 63275]]

species. No mortality is expected to occur as a result of the planned 
surveys, and there is no scientific evidence indicating that any marine 
mammal could experience mortality as a direct result of noise from 
geophysical survey activity. Authorization of mortality may not occur 
via IHAs, and such authorization was neither requested nor proposed. 
Finally, we emphasize that an estimate of take numbers alone is not 
sufficient to assess impacts to a marine mammal population. Take 
numbers must be viewed contextually with other factors, as explained in 
the ``Negligible Impact Analyses and Determinations'' section of this 
Notice.
    Comment: Several commenters referenced studies showing that noise 
from airgun surveys can travel great distances underwater, leading to 
concern that the surveys would impact marine mammals throughout the 
specific geographic region at all times. Some commenters then suggested 
that this would result in there being no available habitat for 
displaced animals to escape to.
    Response: NMFS acknowledges that relatively loud, low-frequency 
noise (as is produced by airgun arrays) has the potential to propagate 
across large distances. However, propagation and received sound levels 
are highly variable based on many biological and environmental factors. 
For example, while one commonly cited study (Nieukirk et al., 2012) 
described detection of airgun sounds almost 4,000 km from the acoustic 
source, the sensors were located within the deep sound channel (SOFAR), 
where low-frequency signals may travel great distances due to the 
advantageous propagation environment. While sounds within this channel 
are unlikely to be heard by most marine mammals due to the depth of the 
SOFAR channel--which is dependent primarily on temperature and water 
pressure and therefore variable with latitude--it is arguable whether 
sounds that travel such distances may be heard by whales as a result of 
refraction to shallower depths (Nieukirk et al., 2012; McDonald et al., 
1995). Regardless, while the extreme propagation distances cited in 
some comments may not be realistic in terms of effects on mysticetes, 
we acknowledge that contraction of effective communication space for 
whales that vocalize and hear at frequencies overlapping those emitted 
by airgun arrays can occur at distances on the order of tens to 
hundreds of kilometers. However, attenuation to levels below the 
behavioral harassment criterion (i.e., 160 dB rms) will likely always 
occur over much shorter distances and, therefore, we do not agree with 
the contention that essentially the entire specific geographic region 
would be ensonified to a degree that marine mammals would find it 
unsuitable habitat. Rather, it is likely that displacement would occur 
within a much smaller region in the vicinity of the acoustic source 
(e.g., within 5-10 km of the source, depending on season and location). 
Overall, the specific geographic region and marine mammal use of the 
area is sufficiently large that, although displacement may occur, the 
region offers enough habitat for marine mammals to seek temporary 
viable habitat elsewhere, if necessary. Many of the affected species 
occupy a wide portion of the region, and it is expected that 
individuals of these species can reasonably find temporary foraging 
grounds or other suitable habitat areas consistent with their natural 
use of the region. Further, although the planned surveys would cover 
large portions of the U.S. Mid- and South Atlantic, they will only be 
transitory in any given area. Therefore, NMFS does not expect 
displacement to occur frequently or for long durations. Importantly, 
for species that show high site fidelity to a particular area (e.g., 
pilot whales around Cape Hatteras) or to bathymetric features (e.g., 
sperm whales and beaked whales), NMFS has required additional time-area 
restrictions to reasonably minimize these impacts.
    Comment: The Bald Head Island Association commented that many 
bottlenose dolphin populations are depleted, and risks from the surveys 
are too great.
    Response: NMFS acknowledges that coastal bottlenose dolphin stocks 
are depleted under the MMPA, and we described the 2013-2015 Unusual 
Mortality Event affecting these stocks in our Notice of Proposed IHAs. 
NMFS is requiring a year-round closure to all survey activity out to 30 
km offshore, including a 20-km distance beyond which encountered 
dolphins would generally be expected to be of the offshore stock and a 
10-km buffer distance that is expected to encompass all received sound 
levels exceeding the 160-dB rms Level B harassment criterion. In 
consideration of this mitigation requirement, NMFS believes that 
impacts to coastal bottlenose dolphins will be minimal.
    Comment: The New York State Department of Environmental 
Conservation expressed concern about impacts from the surveys to 
animals in the New York Bight, noting that even though the surveys 
would not be occurring in the vicinity of New York Bight many of the 
same animals that use the New York Bight for certain life history 
strategies would also be found in certain times of year in the specific 
geographic region.
    Response: Although unrelated to our analyses and necessary findings 
pursuant to the MMPA, we note that in requesting the opportunity to 
conduct review of the proposed surveys pursuant to the Coastal Zone 
Management Act, New York did not demonstrate that the surveys would 
have reasonably foreseeable effects on New York's coastal uses or 
resources. Therefore, New York's request was denied. However, we 
acknowledge that some of the same animals that may occur in the New 
York Bight could also occur at other times of year within the survey 
region and, therefore, be affected by the specified activities. 
However, as detailed elsewhere in this document, we have found for each 
specified activity and each potentially affected species or stock that 
the taking would have a negligible impact.
    Comment: The Natural Resources Defense Council (NRDC) submitted 
comments on behalf of itself and over thirty other organizations, 
including the Center for Biological Diversity, Defenders of Wildlife, 
Earthjustice, The Humane Society of the United States, Sierra Club, et 
al. Hereafter, we refer to this collective letter as ``NRDC.'' NRDC and 
other commenters assert that the surveys will drive marine mammals into 
shipping lanes, thereby increasing their risk of ship strike.
    Response: As an initial matter, we address overall themes in NRDC's 
85-page comment letter. In addition to mischaracterizing the 
literature, likely impacts to marine mammals, and NMFS's analyses in 
multiple places--which we attempt to correct throughout our responses--
the letter repeatedly makes use of undefended or off-point assertions 
(e.g., that NMFS's findings are ``arbitrary and capricious'' and ``non-
conservative''). While we have attempted to clarify and correct 
individual mischaracterizations in our specific responses to comments, 
we broadly address the issue here. NRDC's 16 assertions that NMFS's 
analyses and/or conclusions are ``arbitrary and capricious'' or just 
``arbitrary'' are unfounded. Similarly, NRDC claims that NMFS's 
approaches or decisions are ``non-conservative,'' or should be more 
``conservative,'' at least 15 times, with no indication of what 
standard they are seeking to attain. While NRDC may disagree with the 
issuance of the IHAs or the underlying activities themselves, we 
believe the administrative record for these IHAs amply demonstrates 
that NMFS used the best available science

[[Page 63276]]

during our administrative process to inform our analyses and satisfy 
the standards under section 101(a)(5)(D).
    With regard to this specific comment, the surveys are largely not 
occurring in or near any shipping lanes, as they will occur a minimum 
of 30 km offshore. NMFS is not aware of any scientific information 
suggesting that the surveys would drive marine mammals into shipping 
lanes, and disagrees that this would be a reasonably anticipated effect 
of the specified activities.
    Comment: Comments submitted jointly by Oceana and the International 
Fund for Animal Welfare (hereafter, ``Oceana'') and, separately, by Sea 
Shepherd Legal discuss particular concerns regarding potential impacts 
to large whales. The comments cite studies showing modified singing 
behavior and habitat avoidance among fin whales in response to airguns; 
that sperm whales in the Gulf of Mexico have shown decreased buzz rates 
around airguns; that singing among humpback whales declined in response 
to airgun noise; etc.
    Response: NMFS reviewed all cited studies in making its 
determinations for both the proposed and final IHAs, and agrees that 
there are multiple studies documenting changes in behavior and/or 
communication amongst large whales in response to airgun noise, 
sometimes at significant distance. Changes in vocalization associated 
with exposure to airgun surveys within migratory and non-migratory 
contexts have been observed (e.g., Castellote et al., 2012; Blackwell 
et al., 2013; Cerchio et al., 2014). The potential for anthropogenic 
sound to have impacts over large spatial scales is not surprising for 
species with large communication spaces, like mysticetes (e.g., Clark 
et al., 2009); however, not every change in a vocalization would 
necessarily rise to the level of a take, much less have meaningful 
consequences to the individual or for the affected population. As noted 
previously, the planned surveys are expected to be transient and would 
not result in any sustained impacts to such behaviors for baleen 
whales. We also acknowledge that exposure to noise from airguns may 
impact sperm whale foraging behavior (Miller et al., 2009). However, 
our required mitigation--including time-area restrictions designed to 
protect certain habitat expected to be of importance for foraging sperm 
whales, in addition to standard shutdown requirements expected to 
minimize the severity and duration of any disturbance--when considered 
in context of the transient nature of the impacts possible for these 
surveys lead us to conclude that effects to large whales will be no 
greater than a negligible impact and will be mitigated to the level of 
least practicable adverse impact.
    Comment: Several industry commenters stated, in summary, that there 
is no scientific evidence that geophysical survey activities have 
caused adverse consequences to marine mammal stocks or populations, and 
that there are no known instances of injury to individual marine 
mammals as a result of such surveys, stating that similar surveys have 
been occurring for years without significant impacts. One stated that 
surveys have been ongoing in the Gulf of Mexico for years and have not 
resulted in any negative impacts to marine mammals, including reducing 
fitness in individuals or populations. Referring to other regions, the 
commenters stated that bowhead whale numbers have increased in the 
Arctic despite survey activity. CGG noted that there is no ``empirical 
evidence'' of surveys causing injury or mortality to marine mammals, 
and that previous surveys resulted in less take than authorized. 
Another group added that BOEM has spent $50 million on protected 
species and noise research over four decades with no evidence of 
adverse effects.
    Response: Disruption of behavioral patterns (i.e., Level B 
harassment) has been documented numerous times for marine mammals in 
the presence of airguns (in the form of avoidance of areas, notable 
changes in vocalization or movement patterns, or other shifts in 
important behaviors; see ``Potential Effects of the Specified Activity 
on Marine Mammals and Their Habitat''). Further, lack of evidence for a 
proposition does not prove it is false. In this case, there is growing 
scientific evidence demonstrating the connections between sub-lethal 
effects, such as behavioral disturbance, and population-level effects 
on marine mammals (e.g., Lusseau and Bedjer, 2007; New et al., 2014). 
Disruptions of important behaviors, in certain contexts and scales, 
have been shown to have energetic effects that can translate to reduced 
survivorship or reproductive rates of individuals (e.g., feeding is 
interrupted, so growth, survivorship, or ability to bring young to term 
is compromised), which in turn can adversely affect populations 
depending on their health, abundance, and growth trends.
    Based on the available evidence, a responsible analysis of 
potential impacts of airgun noise on marine mammal individuals and 
populations cannot assume that such effects cannot occur. In reality, 
conclusive statements regarding population-level consequences of 
acoustic stressors cannot be made due to insufficient investigation, as 
such studies are exceedingly difficult to carry out and no appropriate 
study and reference populations have yet been established. For example, 
a recent report from the National Academy of Sciences noted that, while 
a commonly-cited statement from the National Research Council (``[n]o 
scientific studies have conclusively demonstrated a link between 
exposure to sound and adverse effects on a marine mammal population'') 
remains true, it is largely because such impacts are very difficult to 
demonstrate (NRC, 2005; NAS, 2017). Population[hyphen]level effects are 
inherently difficult to assess because of high variability, migrations, 
and multiple factors affecting the populations. However, NMFS has 
carefully considered the available evidence in determining the most 
appropriate suite of mitigation measures and in making the necessary 
determinations (see ``Negligible Impact Analyses and Determinations'').
    Comment: NRDC states that NMFS must consider that behavioral 
disturbance can amount to Level A harassment, or to serious injury or 
mortality, if it interferes with essential life functions through 
secondary effects, stating that displacement from migration paths can 
result in heightened risk of ship strike or predation, especially for 
right whales. In a similar vein, Oceana expressed concern about the 
presence of additional ships in the Atlantic, risking serious injury to 
marine mammals from ship strike or entanglement. Relatedly, NRDC noted 
that NMFS's conclusion that ship strikes will not occur indicates an 
assumption that required ship-strike avoidance procedures will be 
effective. NRDC disagrees that the ship-strike avoidance measures will 
be effective.
    Response: NMFS acknowledges that sufficient disruption of 
behavioral patterns could theoretically, likely in connection with 
other stressors, result in a reduction in fitness and ultimately injury 
or mortality. However, such an outcome could likely result only from 
repeated disruption of important behaviors at critical junctures, or 
sustained displacement from important habitat with no associated 
compensatory ability. No such outcome is expected as a result of these 
surveys, which will be transient in any given area within the large 
overall region, and which avoid some of the most important habitat. 
Effects such as those suggested by NRDC would not be expected for

[[Page 63277]]

right whales, as the surveys are required to avoid migratory pathways 
(80 km from coast), or achieve comparable protection provided through 
implementation of a NMFS-approved mitigation and monitoring plan at 
distances between 47-80 km offshore (see ``Mitigation'' for more 
information).
    Although the primary stressor to marine mammals from the specified 
activities is acoustic exposure to the sound source, NMFS takes 
seriously the risk of vessel strike and has prescribed measures 
sufficient to avoid the potential for ship strike to the extent 
practicable. NMFS has required these measures despite a very low 
likelihood of vessel strike; vessels associated with the surveys will 
add a discountable amount of vessel traffic to the specific geographic 
region (i.e., each survey will operate with roughly 2-3 vessels) and, 
furthermore, vessels towing survey gear travel at very slow speeds 
(i.e., roughly 4-5 kn).
    NMFS's required vessel strike avoidance protocol is expected to 
further minimize any potential interactions between marine mammals and 
survey vessels. Please see ``Vessel Strike Avoidance'' for a full 
description of requirements, which include: Vessels must maintain a 10 
kn speed restriction when in North Atlantic right whale critical 
habitat, Seasonal Management Areas, or Dynamic Management Areas; vessel 
operators and crews must maintain a vigilant watch for all marine 
mammals and must take necessary actions to avoid striking a marine 
mammal; vessels must reduce speeds to 10 kn or less when mother/calf 
pairs, pods, or large assemblages of cetaceans are observed near a 
vessel; and vessels must maintain minimum separation distances.
    Comment: NRDC stated that NMFS did not properly consider potential 
impacts of masking to marine mammals. For example, NRDC notes that NMFS 
addresses masking in the general consequences discussion of its 
negligible impact analysis, but disagrees with NMFS's conclusion that 
consequences are appropriately categorized as ``medium'' rather than 
``high'' for mysticetes, citing the distances at which vocal 
modifications to distant sounds have been detected in low-frequency 
cetaceans and newly-described low-level communication calls between 
humpback whales and their calves, which they suggest have dire 
implications for right whales. NRDC also states that NMFS incorrectly 
thinks masking is co-extensive with the modeled 160-dB rms behavioral 
harassment zones, and suggests that NMFS should take a modeling 
approach to better assess potential masking. Relatedly, another 
commenter stated a belief that NMFS assumes that there is no potential 
for masking during the interpulse interval, when in fact there is noise 
during that period due to multipath arrivals.
    Response: NMFS disagrees that the potential impacts of masking were 
not properly considered. NMFS acknowledges our understanding of the 
literature NRDC cites regarding the greater sensitivity of low-
frequency cetaceans to airgun survey noise via the designation of these 
effects as ``medium,'' but fundamentally, the masking effects to any 
one individual whale from one survey operating far offshore are 
expected to be minimal. Masking is referred to as a chronic effect 
because one of the key harmful components of masking is its duration--
the fact that an animal would have reduced ability to hear or interpret 
critical cues becomes much more likely to cause a problem the longer it 
is occurring. Also, inherent in the concept of masking is the fact that 
the potential for the effect is only present during the times that the 
animal and the source are in close enough proximity for the effect to 
occur (and further this time period would need to coincide with a time 
that the animal was utilizing sounds at the masked frequency) and, as 
our analysis (both quantitative and qualitative components) indicates, 
because of the relative movement of whales and vessels, we do not 
expect these exposures with the potential for masking to be of a long 
duration within a given day. Further, because of the relatively low 
density of mysticetes, the time-area restrictions, and large area over 
which the vessels travel, we do not expect any individual whales to be 
exposed to potentially masking levels from these surveys more than a 
few days in a year.
    NMFS recognizes that masking may occur beyond the 160-dB zone and, 
further, that the primary concern is when numerous sources, many of 
which may be at distances beyond their 160-dB isopleth, contribute to 
higher background noise levels over extended time periods and 
significant portions of an individual's acoustic habitat. However, as 
noted above, any masking effects of these single surveys operating far 
offshore (with no expectation that any of the five would be in close 
enough proximity to one another to contemporaneously expose animals to 
noise from multiple source vessels) are expected to be limited and 
brief, if present. Further, we recognize the presence of multipath 
arrivals, especially the farther the receiver is from the ship, but 
given the reduced received levels at distance, combined with the short 
duration of potential masking and the lower likelihood of extensive 
additional contributors to background noise this far offshore and 
within these short exposure periods, we believe that the incremental 
addition of the seismic vessel is unlikely to result in more than minor 
and short-term masking effects, likely occurring to some small number 
of the same individuals captured in the estimate of behavioral 
harassment.
    In regard to some of the specific examples NRDC raised, we 
acknowledge that vocal modifications of low-frequency cetaceans in 
response to distant sound sources have been detected. However, as 
discussed elsewhere in this Notice, not every behavioral change or 
minor vocal modification rises to the level of a take or has any 
potential to adversely impact marine mammal fitness, and NRDC has not 
demonstrated why it believes the short duration exposures that low-
frequency cetaceans might be exposed to a few times a year from a 
survey should constitute a ``high'' versus ``medium'' consequence in 
NMFS's assessment framework.
    Similarly, NMFS is also aware of the Videsen et al. (2017) paper 
reporting the lower-level communication calls between humpback mother-
calf pairs and noting the increased risk of cow-calf separation with 
increases in background noise. We first note that only neonates were 
tagged and measured in this study (i.e., circumstances could change 
with older calves). Further, while vocalizations between these pairs 
are comparatively lower level than between adults, the cow and neonate 
calf are in regular close proximity (as evidenced by the extent of 
measured sound generated by rubbing in this study), which means that 
the received levels for cow-calf communication are higher than they 
would be if the animals were separated by the distance typical between 
adults--in other words, it is unclear whether these lower-level, but 
close proximity, communications are comparatively more susceptible to 
masking. Assuming that right whale cow-calf pairs use the same lower-
level communication calls, we first note that across all five surveys, 
modeled results estimate that 19 right whales may intercept with the 
tracklines of the surveys such that they are potentially taken and, 
further, as described in the ``Negligible Impact Analyses and 
Determinations'' section and based on available demographic 
information, it should be expected that no more than four exposures 
could be of adult females with calves (not

[[Page 63278]]

specifically neonates). Again, when this very low likelihood of 
encountering cow-calf pairs is combined with the fact that any 
individuals (or cow-calf pairs) would not be expected to be exposed on 
more than a couple/few days in a year, NRDC has not demonstrated how 
the consequences of these activities would be ``catastrophic,'' for 
right whales, and we believe our analysis supports a ``medium'' 
consequence rating.
    Last, in response to the suggestion that we utilize a model, such 
as the model NMFS used for assessing similar potential impacts in the 
Gulf of Mexico, to assess impacts to communication space from the 
surveys evaluated here--it is neither necessary nor an appropriate use 
of those tools. As noted above, the combination of the modeled take 
estimates, along with a qualitative evaluation of the temporal and 
spatial footprint of the activities within the large action area and 
dispersed marine mammal distributions, makes it clear that masking 
effects, if any, would be highly limited for these activities. In the 
Gulf of Mexico, NMFS used the referenced model in the context of a 
five-year rule to programmatically assess the chronic impacts of an 
entire seismic program in a mature and active hydrocarbon-producing 
region, with a significantly greater amount of effort than is 
contemplated in these five surveys, overlaid in an area with already 
otherwise high ambient noise. Use of the model is comparatively 
expensive and time-consuming, and produces a relatively gross-scale 
comparison of predicted annual averages (or other duration) of 
accumulated sound energy (which can also be interpreted in the context 
of the communication space of any species). This sort of analysis can 
be helpful in understanding relative chronic effects when higher and 
longer-term overall levels of activity and impacts are being evaluated 
across areas with notably variable levels of activities and/or ambient 
noise, and can potentially inform decisions regarding time-area 
mitigation. Here, however, any impacts to communication space from any 
individual survey are expected to be minimal; in addition to being 
unnecessary, the lack of granularity in the suggested model (which is 
appropriate at larger and denser scales of impacts, and which can be 
improved with improvement of the available input data) is such that its 
application to these activities would not produce useful information.
    Comment: The South Carolina Environmental Law Project, on behalf of 
the Business Alliance for Protecting the Atlantic Coast, commented that 
chronic stress is possible from the specified activities and that 
likely stress effects would be exacerbated due to their contention that 
avoidance is impossible.
    Response: As described in our Notice of Proposed IHAs, NMFS 
recognizes that stress from acoustic exposure is one potential impact 
of these surveys, and that chronic stress can have fitness, 
reproductive, etc. impacts at the population-level scale. However, we 
believe the possibility for chronic stress is low given the transitory 
and intermittent nature of the sound source (i.e., acoustic exposure in 
specific areas will not be long lasting). The potential for chronic 
stress was evaluated in making the determinations presented in NMFS's 
negligible impact analyses.
    Comment: An individual stated that NMFS did not account for long-
term impacts to species, writing that it is impossible to accurately 
account for impacts without looking at the effects of sound disturbance 
on energy balance (e.g., when disturbance results in additional time 
spent traveling and/or foraging in less optimal habitats, the result 
may be a negative energy balance). The commenter stated further that 
this negative energy balance could have effects both individually and 
cumulatively for a population, and that the cumulative effect of 
behavioral disturbance could be equivalent to a certain amount of 
lethal takes.
    Response: NMFS acknowledges that the concerns raised are 
theoretically possible, but in this case, with limited duration of 
individual surveys or of overlap of multiple surveys, and modeled take 
estimates suggesting that individuals would rarely be impacted by any 
given survey more than a few days in a year, frequent and long-term 
displacement is not expected. Therefore, NMFS does not anticipate 
behavioral disruptions sufficient to negatively impact individual 
energy balances, much less to a degree where long-term effects 
resulting in impacts to recruitment or survival would occur. For 
example, while the available evidence indicates sensitivity to 
disruption of foraging efficiency for sperm whales exposed to airgun 
noise (Miller et al., 2009), a recent bioenergetic modeling exercise 
showed that infrequent, minor disruptions in foraging--as are expected 
in this case--are unlikely to be fatal (Farmer et al., 2018). The 
authors conclude that foraging disruptions would have to be relatively 
frequent to lead to terminal starvation, but continual minor 
disruptions can cause substantial reductions in available reserves. 
Given the temporary, infrequent nature of exposure likely to result 
from the planned surveys, in conjunction with the planned mitigation, 
which includes effort restrictions in areas expected to be of 
importance for sperm whale foraging, it is unlikely that either 
continual minor disruptions or less frequent, but more severe 
disruptions would occur.
    Comment: One individual cited Schnitzler et al. (2017) in stating 
that the varied anatomy of individual sperm whale ears indicates that 
``tolerable'' sound levels may not be the same for different animals.
    Response: NMFS acknowledges that actual individual responses to 
noise exposure will vary based on a variety of factors, including 
individual anatomy but more likely because of individual context and 
experience. However, sufficient scientific information does not exist 
to assess differential impacts to specific individuals. Therefore, NMFS 
uses generic acoustic thresholds in order to predict potential 
responses to noise exposure. However, NMFS has required a sufficiently 
robust suite of mitigation measures to provide reasonable certainty of 
general reduction of takes and of intensity and/or duration of acoustic 
exposures for individual sperm whales.
    Comment: The Bald Head Island Association noted that many marine 
mammals have washed up on their beaches in recent years, including a 
beaked whale and juvenile dolphin after offshore airgun surveys. Sea 
Shepherd Legal claimed that NMFS did not adequately address the 
potential for stranding events, noting several studies that they claim 
link strandings with airgun surveys. They also noted that NMFS did not 
acknowledge a January 2017 mass stranding of false killer whales when 
considering impacts to species.
    Response: Marine mammals are known to strand for a variety of 
reasons, such as infectious agents, biotoxicosis, starvation, fishery 
interaction, ship strike, unusual oceanographic or weather events, 
sound exposure, or combinations of these stressors sustained 
concurrently or in series (e.g., Geraci et al., 1999). However, the 
cause or causes of most strandings are unknown (e.g., Best, 1982). 
Stranding events are known to occasionally happen as a result of sound 
exposure, e.g., Southall et al., 2006, 2013; Jepson et al., 2013; 
Wright et al., 2013, with stranding thought to occur subsequent to the 
exposure, as a result of non-auditory physiological effects or 
injuries, which theoretically might occur as a secondary effect of 
extreme behavioral reactions (e.g., change in dive profile as a result 
of an avoidance reaction). However, such events are typically 
associated with use of military

[[Page 63279]]

tactical sonar, which has very different characteristics than airgun 
noise.
    NMFS is unaware of any information linking possible strandings on 
Bald Head Island, or in any other location on the East Coast, with 
offshore airgun survey activity, and does not expect the planned 
surveys to have any potential to result in stranding events or the type 
of injuries or effects that could lead to stranding events, given the 
required mitigation and operational protocols. In support of its 
position, Sea Shepherd Legal cites two review articles (Gordon et al., 
2003; Compton et al., 2008) that make general statements regarding the 
potential effects of airgun noise and/or review best practices in 
mitigation--NMFS reviewed these papers and discussed them in our Notice 
of Proposed IHAs. Sea Shepherd also cites a third document (Engel et 
al., 2004) questioning whether such surveys may be responsible for 
coincident strandings of humpback whales in Brazil in 2002, and notes 
NMFS's discussion of a 2002 beaked whale stranding event that was 
contemporaneous with and reasonably associated spatially with an airgun 
survey in the Gulf of California. However, unlike for strandings 
associated with use of military sonar, no conclusive causal link was 
made, and these observations remain based on spatial and/or temporal 
coincidence. NMFS here acknowledges the 2017 stranding of false killer 
whales in Florida referenced by Sea Shepherd Legal, for which no cause 
was found.
    However, as a precaution NMFS has modified its reporting 
requirements to include protocols relating to minimization of 
additional harm to live-stranded (or milling) marine mammals. Addition 
of these protocols does not imply any change to our determination that 
stranding events are unlikely, nor does it imply that a stranding event 
that does occur is necessarily the result of the specified activities. 
However, we recognize that regardless of the cause of a stranding 
event, it is appropriate to take action in certain circumstances to 
avoid additional harm. Please see ``Monitoring and Reporting'' for more 
information.

Marine Mammal Impacts--Habitat

    Comment: Many commenters expressed concern regarding potential 
impacts to marine mammal prey and/or food webs from the planned 
surveys. NRDC specifically provided numerous citations in claiming that 
the surveys could impact marine mammal prey through the following: (1) 
Cause severe physical injury and mortality; (2) damage hearing and 
sensory abilities of fish and marine invertebrates; (3) impede 
development of early life history stages; (4) induce stress that 
physically damages marine invertebrates and compromises fish health; 
(5) cause startle and alarm responses that interrupt vital behaviors; 
(6) alter predator avoidance behavior that may reduce probability of 
survival; (7) affect catchability of prey species; (8) mask important 
biological sounds essential to survival; (9) reduce reproductive 
success, potentially jeopardizing long-term sustainability of fish 
populations; (10) interrupt feeding behaviors and induce other species-
specific effects that may increase risk of starvation, reduce 
reproduction, and alter community structure; and (11) compromise 
orientation of fish larvae with potential ecosystem-level effects. 
Additionally, many commenters cited a recent publication by McCauley et 
al. (2017) as evidence that the surveys could potentially impact 
zooplankton and consequently marine mammal food webs.
    In contrast, the International Association of Geophysical 
Contractors, American Petroleum Institute, and National Ocean 
Industries Association (hereafter, ``the Associations'') stated that 
McCauley et al. (2017) ``purports to demonstrate, but fails to prove, 
that seismic survey air sources negatively impact zooplankton.'' The 
Associations cite small sample size, variability in the baseline and 
experimental data, and the ``large number of speculative conclusions 
that appear to be inconsistent with the data collected over a two-day 
period'' in stating that the research ``creates no reasonable 
implication regarding the potential effects of seismic surveys on 
marine mammals.''
    Response: NMFS strongly disagrees with NRDC's contention that we 
ignored effects to prey species; in fact, we considered relevant 
literature (including that cited by NRDC) in finding that the most 
likely impact of survey activity to prey species such as fish and 
invertebrates would be temporary avoidance of an area, with a rapid 
return to recruitment, distribution, and behavior anticipated. While 
there is a lack of specific scientific information to allow an 
assessment of the duration, intensity, or distribution of effects to 
prey in specific locations at specific times and in response to 
specific surveys, NMFS's review of the available information does not 
indicate that such effects could be significant enough to impact marine 
mammal prey to the extent that marine mammal fitness would be affected. 
A more detailed discussion is provided in ``Potential Effects of the 
Specified Activities on Marine Mammals and Their Habitat.''
    In summary, fish react to sounds which are especially strong and/or 
intermittent low-frequency sounds, and behavioral responses such as 
flight or avoidance are the most likely effects. However, the reaction 
of fish to airguns depends on the physiological state of the fish, past 
exposures, motivation (e.g., feeding, spawning, migration), and other 
environmental factors. While we agree that some studies have 
demonstrated that airgun sounds might affect the distribution and 
behavior of some fishes, potentially impacting foraging opportunities 
or increasing energetic costs (e.g., Fewtrell and McCauley, 2012; 
Pearson et al., 1992; Skalski et al., 1992; Santulli et al., 1999; 
Paxton et al., 2017), other studies have shown no or slight reaction to 
airgun sounds (e.g., Pena et al., 2013; Wardle et al., 2001; Jorgenson 
and Gyselman, 2009; Cott et al., 2012). Most commonly, though, the 
impacts of noise on fish are temporary. Investigators reported 
significant, short-term declines in commercial fishing catch rate of 
gadid fishes during and for up to five days after survey operations, 
but the catch rate subsequently returned to normal (Engas et al., 1996; 
Engas and Lokkeborg, 2002); other studies have reported similar 
findings (Hassel et al., 2004).
    As discussed by NRDC, however, even temporary effects to fish 
distribution patterns can impact their ability to carry out important 
life-history functions. SPLs of sufficient strength have been known to 
cause injury to fish and fish mortality and, in some studies, fish 
auditory systems have been damaged by airgun noise (McCauley et al., 
2003; Popper et al., 2005; Song et al., 2008). However, in most fish 
species, hair cells in the ear continuously regenerate and loss of 
auditory function likely is restored when damaged cells are replaced 
with new cells. Halvorsen et al. (2012b) showed that a TTS of 4-6 dB 
was recoverable within 24 hours for one species. Impacts would be most 
severe when the individual fish is close to the source and when the 
duration of exposure is long--both of which are conditions unlikely to 
occur during these surveys, which will be transient in any given 
location and likely result in brief, infrequent noise exposure to prey 
species in any given area. For these surveys, the sound source is 
constantly moving, and most fish would likely avoid the sound source 
prior to receiving sound of sufficient intensity to cause physiological 
or anatomical damage. In addition, ramp-up may

[[Page 63280]]

allow certain fish species the opportunity to move further away from 
the sound source.
    Available data suggest that cephalopods are capable of sensing the 
particle motion of sounds and detect low frequencies up to 1-1.5 kHz, 
depending on the species, and so are likely to detect airgun noise 
(Kaifu et al., 2008; Hu et al., 2009; Mooney et al., 2010; Samson et 
al., 2014). Auditory injuries (lesions occurring on the statocyst 
sensory hair cells) have been reported upon controlled exposure to low-
frequency sounds, suggesting that cephalopods are particularly 
sensitive to low-frequency sound (Andre et al., 2011; Sole et al., 
2013). Behavioral responses, such as inking and jetting, have also been 
reported upon exposure to low-frequency sound (McCauley et al., 2000b; 
Samson et al., 2014). Similar to fish, however, the transient nature of 
the surveys leads to an expectation that effects will be largely 
limited to behavioral reactions and would occur as a result of brief, 
infrequent exposures.
    With regard to potential impacts on zooplankton, McCauley et al. 
(2017) found that exposure to airgun noise resulted in significant 
depletion for more than half the taxa present and that there were two 
to three times more dead zooplankton after airgun exposure compared 
with controls for all taxa, within 1 km of the airguns. However, the 
authors also stated that in order to have significant impacts on r-
selected species such as plankton, the spatial or temporal scale of 
impact must be large in comparison with the ecosystem concerned, and it 
is possible that the findings reflect avoidance by zooplankton rather 
than mortality (McCauley et al., 2017). In addition, the results of 
this study are inconsistent with a large body of research that 
generally finds limited spatial and temporal impacts to zooplankton as 
a result of exposure to airgun noise (e.g., Dalen and Knutsen, 1987; 
Payne, 2004; Stanley et al., 2011).
    A modeling exercise was conducted as a follow-up to the McCauley et 
al. (2017) study (as recommended by McCauley et al. (2017)), in order 
to assess the potential for impacts on ocean ecosystem dynamics and 
zooplankton population dynamics (Richardson et al., 2017). Richardson 
et al. (2017) found that for copepods with a short life cycle in a 
high-energy environment, a full-scale airgun survey would impact 
copepod abundance up to three days following the end of the survey, 
suggesting that effects such as those found by McCauley et al. (2017) 
would not be expected to be detectable downstream of the survey areas, 
either spatially or temporally. However, these findings are relevant 
for zooplankton with rapid reproductive cycles in areas where there is 
a high natural replenishment rate resulting from new water masses 
moving in, and the findings may not apply in lower-energy environments 
or for zooplankton with longer life-cycles. In fact, the study found 
that by turning off the current, as may reflect lower-energy 
environments, the time to recovery for the modelled population extended 
from several days to several weeks.
    However, while potential impacts to zooplankton are of obvious 
concern with regard to their follow-on effects for higher-order 
predators, the survey area is not an important area for feeding for 
taxa that feed directly on zooplankton, i.e., mysticetes. In the 
absence of further validation of the McCauley et al. (2017) findings, 
if we assume a worst-case likelihood of severe impacts to zooplankton 
within approximately 1 km of the acoustic source, the large spatial 
scale and expected wide dispersal of survey vessels does not lead us to 
expect any meaningful follow-on effects to the prey base for odontocete 
predators. While the large scale of effect observed by McCauley et al. 
(2017) may be of concern, especially in a more temperate environment, 
NMFS concludes that these findings indicate a need for more study, 
particularly where repeated noise exposure is expected--a condition 
unlikely to occur in relation to these planned surveys. We do not offer 
further comment with regard to the specific criticisms of the 
Associations, other than to say that their dismissal of the study seems 
to reflect an unsubstantiated opinion.
    Overall, prey species exposed to sound might move away from the 
sound source, experience TTS, experience masking of biologically 
relevant sounds, or show no obvious direct effects. Mortality from 
decompression injuries is possible in close proximity to a sound, but 
only limited data on mortality in response to airgun noise exposure are 
available (Hawkins et al., 2014). The most likely impacts for most prey 
species in a given area would be temporary avoidance of the area. The 
surveys are expected to move through an area relatively quickly, 
limiting exposure to multiple impulsive sounds. In all cases, sound 
levels would return to ambient once a survey ends and the noise source 
is shut down and, when exposure to sound ends, behavioral and/or 
physiological responses are expected to end relatively quickly 
(McCauley et al., 2000b). The duration of fish avoidance of a given 
area after survey effort stops is unknown, but a rapid return to normal 
recruitment, distribution, and behavior is anticipated. While the 
potential for disruption of spawning aggregations or schools of 
important prey species can be meaningful on a local scale, the mobile 
and temporary nature of the surveys and the likelihood of temporary 
avoidance behavior suggest that impacts would be minor.
    Comment: A group of scientists (C.W. Clark, S.D. Kraus, D.P. 
Nowacek, A.J. Read, M. Rekdahl, A.N. Rice, H. Rosenbaum, and R.S. 
Schick) submitted a collective comment letter. Hereafter, we refer to 
this letter as ``Nowacek et al.'' Nowacek et al. and NRDC stated that 
it is inappropriate to conclude that these surveys will not impact 
marine mammal acoustic habitat, since the production of airgun noise is 
known to increase ambient noise, thereby negatively impacting habitat. 
NRDC further states that NMFS has failed to adequately account for 
impacts to acoustic habitat. In support of their statements, Nowacek et 
al. submitted the results of a sound field modeling exercise in which 
they considered energy produced from seven shots of a 40-element array 
at 6 m depth (other important source details were not provided) across 
one-third-octave bands spanning the 71-224 Hz frequency range. 
Resulting sound fields were concatenated at 1-s resolution for two 
different water depths (50 and 200 m) (commenters submitted animations 
associated with this exercise; these are available upon request and are 
part of our administrative record for these actions). They wrote that 
these animations highlight the dynamic nature of the marine 
environment, especially the low-frequency sound field, and the large 
area over which sound levels are increased above ambient levels but 
below current regulatory harassment thresholds. The commenters then 
correctly note that consideration of likely takes is limited to just a 
portion of the area over which airgun noise extends into the marine 
environment. Nowacek et al. also recommended that NMFS produce a 
quantitative methodology for assessing the region's acoustic 
environment, the proportional contributions from each of the natural 
and anthropogenic noise inputs, and create mechanisms to mitigate these 
lower-level noise exposures.
    Response: The commenters' claims that NMFS concluded that there 
``would be no impact to the quality of the acoustic habitat'' or 
suggested that ``there is no basis for acoustic habitat impacts'' are 
erroneous. NMFS made no such statements, but rather

[[Page 63281]]

acknowledged in our Notice of Proposed IHAs that it was likely that 
there would be impacts to acoustic habitat, particularly for low-
frequency cetaceans. In fact, we explicitly considered this likelihood 
in our preliminary negligible impact analyses, finding that 
``consequence'' of the surveys should be considered as higher for 
mysticete whales than for other species for this reason.
    NMFS addressed potential effects to habitat, including acoustic 
habitat, and acknowledges that the surveys will increase noise levels 
in the vicinity of operating source vessels. However, following 
consideration of the available information, NMFS concludes that these 
impacts will not significantly affect ambient noise levels or acoustic 
communication space over long time periods, especially in the context 
of any given exposed individual. As described previously, exploratory 
surveys such as these cover a large area but would be transient rather 
than focused in a given location over time and therefore would not be 
considered as contributing meaningfully to chronic effects in any given 
location. Given these conclusions, a separate quantitative analysis of 
potential impacts to acoustic habitat, as is suggested by Nowacek et 
al., is not warranted. In contrast, we did develop and perform such 
analysis for a different assessment of much more extensive geophysical 
survey activity (see Appendix K in BOEM, 2017) to be conducted over a 
period of ten years, versus the limited amount of survey activity to be 
conducted over a period of one year here.
    We acknowledge and appreciate the commenters' scientific expertise, 
but there are relevant statutory and regulatory requirements that 
inform NMFS in the scope of analysis relevant to a finding of 
negligible impact. Please see also our response to a previous comment 
above, in which NRDC makes similar charges regarding the impacts of 
masking. Finally, regarding terminology used in the comments (i.e., 
``primary constituent elements''), the discussion in this document 
pertains specifically to the MMPA and not components related to 
critical habitat designated under the ESA.
    Comment: The Sierra Club Marine Group noted that Cape Hatteras has 
a very unique morphology, and that these features support upwelling 
that supports significant biodiversity, including beaked whales. The 
commenters stated that impacts to this habitat provide a compelling 
reason to deny the IHAs.
    Response: As described in our Notice of Proposed IHAs, NMFS concurs 
that Cape Hatteras provides important habitat for a diverse assemblage 
of species, particularly for species such as sperm whales, beaked 
whales, pilot whales, and other species that show high site fidelity to 
the area. Accordingly, NMFS has designed a time-area restriction 
encompassing the area referenced in the comment that precludes survey 
effort within the area for a three-month period (January to March; 
Stanistreet et al., 2018); the restriction is defined specifically to 
benefit beaked whales, sperm whales, and pilot whales, with the 
specific timing intended as the most appropriate for sperm whales. We 
also require mitigation to reduce the intensity and duration of 
exposure for these species--particularly for acoustically sensitive 
species, such as beaked whales, for which shutdown is required at an 
extended distance of 1.5 km. Separately, NMFS has required year-round 
closures of similar high-relief habitats further offshore that are 
predicted to host relatively high densities of beaked whales. In 
addition, the North Atlantic right whale closure will protect portions 
of the area referenced by the commenters, as it extends out to 90 km 
from the coastline (i.e., 80 km plus a 10 km buffer, see 
``Mitigation'') and is in effect from November through April (or 
comparable protection provided through implementation of a NMFS-
approved mitigation and monitoring plan at distances between 47-80 km 
offshore), whereas the seasonal restriction off of Cape Hatteras is in 
effect from January through March. NMFS believes these restrictions 
provide a high degree of protection to these species and the habitat 
they utilize around Cape Hatteras, while meeting the MMPA's least 
practicable adverse impact standard. When the contextual factor 
addressing required mitigation is considered, the outcome is a 
negligible impact to affected species.
    Comment: An individual states that the surveys have the potential 
to impair the Chesapeake Bay, and that such impairment would have wider 
ecological and economic repercussions beyond the scope of impacting 
marine mammals. Similarly, one group mentioned that impacts from the 
surveys could ripple into smaller bays and inlets elsewhere along the 
East Coast, and impact species long after surveys are complete.
    Response: NMFS's action is authorizing the taking of marine mammals 
pursuant to section 101(a)(5)(D); therefore, impacts of the survey on 
aspects of the environment other than marine mammals and their habitat 
are not relevant to NMFS's analysis conducted pursuant to the MMPA. 
However, the authorization of marine mammal take incidental to the 
planned surveys would not impact marine mammals of the Chesapeake Bay 
or of other coastal bays and estuaries. Surveys may not operate closer 
than 30 km to shore at any time.

North Atlantic Right Whale

    Comment: Many commenters expressed concern regarding the North 
Atlantic right whale and potential impacts of the specified activities, 
given their declining population size, an ongoing Unusual Mortality 
Event (UME), declining calf production, and annual exceedances of the 
calculated potential biological removal value (see ``Description of 
Marine Mammals in the Area of the Specified Activities--North Atlantic 
Right Whale'' for further discussion of these issues). Some commenters 
noted additional concern regarding potential survey overlap with 
biologically important areas. Others highlighted concerns regarding 
increased risk of ship strike and/or entanglement with survey vessels, 
in addition to the potential for acoustic and behavioral effects.
    Response: NMFS appreciates the concerns expressed by commenters 
regarding right whales. As an agency, NMFS is working to address the 
numerous issues facing right whales, including continued work to reduce 
deaths due to ship strike and entanglement in fishing gear and ongoing 
investigation of the UME, as well as other measures to investigate and 
address the status of the species. The best available scientific 
information shows that the majority of right whale sightings in the 
southeast occur in right whale calving areas from roughly November 
through April, with individual right whales migrating to and from these 
areas through mid-Atlantic shelf waters. Because of these concerns 
regarding right whales, NMFS is requiring closure of these areas (out 
to 90 km from shore) to survey activity from November 1 to April 30 (or 
that comparable protection is achieved through implementation of a 
NMFS-approved mitigation and monitoring plan at distances between 47-80 
km offshore). This measure is expected to largely avoid disruption of 
behavioral patterns for right whales and to minimize overall acoustic 
exposures. Therefore, NMFS believes that this restriction provides for 
migratory passage to and from calving grounds as well as avoiding 
impacts to the whales while on the grounds. In addition, NMFS re-
evaluated potential right whale takes using the best available

[[Page 63282]]

scientific information (i.e., Roberts et al., 2017) and in 
consideration of the revised time-area restriction. The result of this 
analysis shows that takes of right whales will be minimal.
    Comment: NRDC and, separately, Nowacek et al. state that airgun 
surveys have been linked to significant reductions in the probability 
of calf survival in western Pacific gray whales (another endangered 
baleen whale population), claiming that these findings indicate that 
similar surveys off the southeastern U.S will have significant negative 
effects on the whales that occur anywhere in the region.
    Response: Commenters cite a preliminary report (Cooke et al., 2015) 
that documented a reduction in calf survival that they suggested may be 
related to disruption of foraging from airgun survey activity and pile 
driving in Russia due to presumed avoidance of foraging areas. However, 
a more recent analysis (Cooke et al., 2017) invalidated these findings, 
showing that this was a sampling effect, as those calves that were 
assumed dead in the 2015 study have since been observed alive 
elsewhere. The new study found no significant annual variation in calf 
survival. Johnson et al. (2007) had previously reported that foraging 
gray whales exposed to airgun sounds during surveys in Russia did not 
experience any biologically significant or population-level effects.
    Comment: J.J. Roberts and P.N. Halpin of the Duke University Marine 
Geospatial Ecology Lab (hereafter, ``MGEL'') provided two comments 
related to right whales. First, the commenters stated, in summary, that 
the time-area restriction included in our Notice of Proposed IHAs for 
the specific purpose of avoiding impacts to the North Atlantic right 
whale would not be sufficient to achieve its stated purpose. The 
commenters noted multiple lines of scientific evidence that right 
whales occur beyond the area defined in the Notice of Proposed IHAs 
(i.e., a 20-nmi coastal strip, superseded by either critical habitat or 
seasonal management areas, and buffered by a distance of 10 km; this 
equates roughly to a 47-km coastal strip). The commenters also 
reiterated concern regarding an error associated with the right whale 
take estimates for two applicants (TGS and Western). Finally, the 
commenters noted that they were developing updated density models for 
the right whale; these revised models more than double the survey 
effort utilized by the models in the region south of Cape Hatteras, 
while additional new data boost coverage in non-summer seasons. As 
stated by the commenters, collectively these data allow for a notable 
upgrade in right whale density model performance in the regions and 
seasons addressed here. The commenters noted that, while the revised 
models have not been through formal peer review, they utilize the same 
methodology as the Roberts et al. (2016) publication, which has been 
peer reviewed.
    Response: We agree with these comments, and addressed them through 
use of the revised North Atlantic right whale models (Roberts et al., 
2017) in developing new exposure estimates for all five applicant 
companies. Importantly, in agreement with the statements of the 
commenters and with the outputs of the revised models, we revised the 
time-area restriction by increasing the standoff distance from shore to 
90 km (i.e., 80 km plus a 10 km buffer) (or requiring that comparable 
protection is achieved through implementation of a NMFS-approved 
mitigation and monitoring plan at distances between 47-80 km offshore). 
As stated by MGEL and other commenters, Norris et al. (2014) reported 
acoustic detections of right whales in the southeast beyond the 
previous 47 km limit, while Foley et al. (2011) documented a right 
whale birth beyond the previous limit. The right whale model produced 
by Roberts et al. (2016) explicitly included distance from shore as a 
predictor in the model; right whale densities significantly above zero 
were predicted beyond the proposed 47 km limit. The revised model 
retains distance from shore as a predictor and, in the region north of 
Cape Fear, indicates that right whale density peaks at about 50 km 
offshore during the winter and is moderate to about 80 km from shore, 
beyond which limit density is predicted as dropping off rapidly. Please 
see ``Estimated Take--North Atlantic Right Whale'' and ``Mitigation'' 
for additional discussion.
    Comment: Nowacek et al. commented that NMFS should perform a 
quantitative evaluation of right whale health and reproductive rates, 
including mortality and sublethal effects of entanglement. They noted 
that tools such as the Population Consequences of Disturbance (PCOD) 
model could be used to perform such an analysis. However, Nowacek et 
al. provided their own modeling example, including a health assessment 
of five North Atlantic right whales, which they described in their 
comment letter. Nowacek et al.'s analysis showed that a small decrement 
in health that could be linked to stress caused by chronic noise 
exposure can result in negative consequences for individual right 
whales.
    Response: NMFS appreciates the attention given to this issue by the 
commenters, and finds the analysis provided in their letter useful. As 
noted by many commenters, the primary threats to the right whale remain 
ship strike and entanglement in fishing gear. However, NMFS considered 
this analysis and its conclusions in its determination to revisit the 
acoustic exposure analysis conducted for right whales and in 
reconsidering the most appropriate habitat-based mitigation 
requirements related to right whales. Following these new analyses, 
NMFS finds that predicted takes of right whales have been substantially 
reduced and that potential impacts to the right whale have been reduced 
to the level of least practicable adverse impact. While it is likely 
not possible to completely avoid acoustic exposures of North Atlantic 
right whales, NMFS finds that such exposures will be minimized and 
that, importantly, the impact of acoustic exposures will be minimized 
by avoiding entirely the habitat expected to be important for right 
whales for calving and migratory behavior (or that comparable 
protection is achieved through implementation of a NMFS-approved 
mitigation and monitoring plan at distances between 47-80 km offshore). 
In the event that right whales are encountered outside these areas, the 
expanded shutdown requirement will minimize the severity and/or 
duration of acoustic exposures. Finally, while exposures of right 
whales at levels below those expected to result in disruption of 
behavioral patterns but above the level of ambient noise may occur, 
NMFS does not consider such potential exposures as likely to constitute 
``chronic noise exposure,'' as a result of the relatively brief 
duration of any given survey in any particular location; therefore, it 
is unlikely that the specified activities could result in impacts such 
as those assessed through the analysis of Nowacek et al.
    Comment: One commenter described the relationship between noise and 
stress shown by Rolland et al. (2012) for right whales, stating that 
the planned surveys could increase stress in right whales.
    Response: While NMFS concurs that the findings of Rolland et al. 
(2012) indicate a connection between noise exposure and stress in right 
whales, the number of vessels associated with the surveys is unlikely 
to contribute to significant additive vessel traffic and associated 
vessel noise as compared with vessel activity already occurring in the 
region. Rolland et al. (2012)

[[Page 63283]]

measured vessel density in an area with much more concentrated activity 
(i.e., shipping lanes in the Bay of Fundy) than what would occur in the 
activity area. While noise from the surveys, whether due to use of the 
airgun arrays or from the vessels themselves, may cause stress 
responses in exposed animals, NMFS finds it unlikely that such 
responses will significantly impact individual whales as chronic noise 
exposure is not expected.
    Comment: Several groups commented on additional data NMFS should 
have considered in assessing impacts to North Atlantic right whales. 
For example, the Marine Mammal Commission (MMC) recommended that we 
consult with NMFS's Northeast Fisheries Science Center regarding 
results of their most recent acoustic analysis, which they contend may 
provide insight on occurrence of right whales at different distances 
from shore. Similarly, Nowacek et al. recommended that NMFS should 
consider more recent data from the Atlantic Marine Assessment Program 
for Protected Species (AMAPPS) surveys or right whale surveys in the 
southeast curated by the North Atlantic Right Whale Consortium. NRDC 
stated that NMFS must use additional data sources in calculating right 
whale densities, noting that recent passive acoustic studies have 
detected whales further offshore and with broader seasonality than 
previously expected.
    Response: NMFS agrees with these comments, and has considered these 
various sources of newer data, including by revising acoustic exposure 
estimates for right whales by using the latest density models for right 
whales (Roberts et al., 2017). These revised models incorporate the 
southeast U.S. right whale survey data as well as the AMAPPS data. 
While the revised model does not directly incorporate acoustic data--we 
note that NRDC offers no suggestions as to how this might be 
accomplished--it was validated through comparison with passive acoustic 
monitoring data (Davis et al., 2017). While this validation work does 
suggest that the revised model may underestimate right whale presence 
in certain locations or seasons--for example, acoustic data indicate 
that the model may underestimate the presence of whales relatively far 
from shore during the winter in the region north of Cape Hatteras--we 
developed an extended right whale closure (out to 90 km from shore) (or 
we require that comparable protection is achieved through 
implementation of a NMFS-approved mitigation and monitoring plan at 
distances between 47-80 km offshore) in an effort to reasonably 
encompass the likelihood of increased whale presence at greater 
distances from shore than have previously been expected.
    Comment: Sea Shepherd Legal stated that NMFS ignored the ``Cetacean 
& Sound Mapping platform (``CetSound'')'' when discussing biologically 
important areas for North Atlantic right whales.
    Response: Though NMFS did not give specific reference to 
``CetSound'' in our Notice of Proposed IHAs, we did in fact incorporate 
and consider information available through NOAA's CetSound website 
(cetsound.noaa.gov), including information relating to BIAs, as 
discussed by LaBrecque et al. (2015).

Cumulative Impacts and Related Issues

    Comment: Many commenters expressed concern regarding 
``cumulative,'' ``aggregate'' and ``synergistic'' impacts. Commenters 
stated that NMFS did not adequately address cumulative or aggregate 
impacts from the five surveys, which are planned to occur within the 
same broad geographic region and which could overlap temporally. Some 
commenters referenced the large amount of survey effort described in 
BOEM's PEIS, erroneously ascribing the potential cumulative impacts 
associated with that level of effort--associated with nine years of 
surveys in support of an active oil and gas program in the Atlantic--to 
the significantly smaller amount of activity contemplated in our five 
separate proposed IHAs. Commenters urged the agency to review 
cumulative impacts using a risk-averse approach, considering such 
impacts in the context of effects to both species and ecosystems, as 
well as across time and geographic extent. As discussed in a previous 
comment response, some commenters cited studies demonstrating potential 
long-range propagation of airgun signals as reason for additional 
consideration of cumulative impacts. Similarly, some commenters claimed 
a need to consider takes in the aggregate and to consider potential 
takes from other sources. Nowacek et al. specified that NMFS should 
assess aggregate impacts in addition to cumulative impacts, 
highlighting available tools to do so. One commenter suggested that a 
cumulative noise management plan should be developed. Commenters such 
as Nowacek et al. decry our independent consideration of the effects of 
each individual specified activity under the MMPA as ``completely 
without basis in science or logic.'' Similarly, NRDC claims that 
failing to consider the total impact of all five surveys in the 
negligible impact assessment does not satisfy NMFS's legal obligations 
and is ``contrary to common sense and principles of sound science.'' 
NRDC also states that NMFS's negligible impact determination 
underestimates impacts to marine mammal species and populations because 
it fails to consider the effects of other anticipated activities on the 
same marine mammal populations. Finally, some commenters acknowledged 
that the MMPA does not require consideration of cumulative impacts but 
stated that NMFS must do so in this case given the unprecedented scale 
of these surveys in the Atlantic.
    Response: Cumulative impacts (also referred to as cumulative 
effects) is a term that appears in the context of NEPA and the ESA, but 
it is defined differently in those different contexts. Neither the MMPA 
nor NMFS's codified implementing regulations address consideration of 
other unrelated activities and their impacts on populations. However, 
the preamble for NMFS's implementing regulations (54 FR 40338; 
September 29, 1989) states in response to comments that the impacts 
from other past and ongoing anthropogenic activities are to be 
incorporated into the negligible impact analysis via their impacts on 
the environmental baseline. Consistent with that direction, NMFS here 
has factored into its negligible impact analyses the impacts of other 
past and ongoing anthropogenic activities via their impacts on the 
baseline (e.g., as reflected in the density/distribution and status of 
the species, population size and growth rate, and other relevant 
stressors (such as incidental mortality in commercial fisheries)). In 
addition, the context aspect of our assessment framework also considers 
these factors. See the ``Negligible Impact Analyses and 
Determinations'' section of this notice.
    Our 1989 final rule for the MMPA implementing regulations also 
addressed public comments regarding cumulative effects from future, 
unrelated activities. There we stated that such effects are not 
considered in making findings under section 101(a)(5) concerning 
negligible impact. We indicated that NMFS would consider cumulative 
effects that are reasonably foreseeable when preparing a NEPA analysis; 
and also that reasonably foreseeable cumulative effects would be 
considered under section 7 of the ESA for ESA-listed species.
    In this case, we deem each of these IHAs a future, unrelated 
activity relative to the others. Although these IHAs are all for 
surveys that will be conducted for

[[Page 63284]]

a similar purpose, they are unrelated in the sense that they are 
discrete actions under section 101(a)(5)(D), issued to discrete 
applicants.
    Here, we recognize the potential for cumulative impacts, and that 
the aggregate impacts of the five surveys will be greater than the 
impacts of any given survey. The direct aggregate impacts of multiple 
surveys were addressed through the associated NEPA analyses: In BOEM's 
PEIS, which addressed the impacts of a significantly greater amount of 
survey activity that may be permitted by BOEM, and which NMFS adopted 
as the basis for its Record of Decision; as well as in NMFS's tiered 
Environmental Assessment, which supported a Finding of No Significant 
Impact (FONSI) for the issuance of the five IHAs here.
    In our FONSI, NMFS's assessment was focused on whether the 
predicted level of take from the five surveys, when considered in 
context, would have a meaningful biological consequence at a species or 
population level. NMFS, therefore, assessed and integrated other 
contextual factors (e.g., species' life history and biology, 
distribution, abundance, and status of the stock; mitigation and 
monitoring; characteristics of the surveys and sound sources) in 
determining the overall impact of issuance of the five IHAs on the 
human environment. Key considerations included the nature of the 
surveys and the required mitigation. In all cases, it is expected that 
sound levels will return to previous ambient levels once the acoustic 
source moves a certain distance from the area, or the surveys cease, 
and it is unlikely that the surveys will all occur at the same time in 
the same places, as the area within which the surveys will occur is 
very large and some will occur for less than six months. In other 
words, we would not expect the duration of a sound source to be greater 
than moderate and intermittent in any given area. Surveys have been 
excluded from portions of the total area deemed to result in the 
greatest benefit to marine mammals. These restrictions will not only 
reduce the overall numbers of take but, more importantly, will 
eliminate or minimize impacts to marine mammals in the areas most 
important to them for feeding, breeding, and other important functions. 
Therefore, these measures are expected to meaningfully reduce the 
severity of the takes that do occur by limiting impacts that could 
reduce reproductive success or survivorship.
    In summary, NMFS finds that when the required mitigation and 
monitoring is considered in combination with the large spatial extent 
over which the activities are spread across for comparatively short 
durations (less than one year), the potential impacts are both 
temporary and relatively minor. Therefore, NMFS does not expect 
aggregate impacts from the five surveys to marine mammals to affect 
rates of recruitment or survival, either alone or in combination with 
other past, present, or ongoing activities. The cumulative impacts of 
these surveys (i.e., the incremental impact of the action when added to 
other past, present, and reasonably foreseeable future actions) were 
addressed as required through the NEPA documents cited above and, as 
noted, supported a FONSI for the five IHAs. These documents, as well as 
the relevant Stock Assessment Reports, are part of NMFS's 
Administrative Record for this action, and provided the decision-maker 
with information regarding other activities in the action area that 
affect marine mammals, an analysis of cumulative impacts, and other 
information relevant to the determinations made under the MMPA.
    Separately, cumulative effects were analyzed as required through 
NMFS's required intra-agency consultation under section 7 of the ESA, 
which concluded that NMFS's action of issuing the five IHAs was not 
likely to jeopardize the continued existence of listed marine mammals 
and was not likely to adversely affect any designated critical habitat.
    We note that section 101(a)(5)(D) of the MMPA requires NMFS to make 
a determination that the take incidental to a ``specified activity'' 
will have a negligible impact on the affected species or stocks of 
marine mammals, and will not result in an unmitigable adverse impact on 
the availability of marine mammals for taking for subsistence uses. We 
believe the ``specified activity'' for which incidental take coverage 
is being sought under section 101(a)(5)(D) is appropriately defined and 
described by the IHA applicant, just as with applications submitted for 
section 101(a)(5)(A) incidental take regulations. Here there are five 
specified activities, with a separate applicant for each. NMFS must 
make the necessary findings for each specified activity.
    Comment: Several commenters discussed a recent report from the 
National Academy of Sciences concerning cumulative impacts to marine 
mammals (``Approaches to Understanding the Cumulative Effects of 
Stressors on Marine Mammals''; NAS, 2017), suggesting that NMFS should 
have reviewed this report in addressing cumulative impacts.
    Response: NMFS acknowledges the importance of this new report, 
which was not available at the time of writing for our Notice of 
Proposed IHAs. We reviewed this report and considered its findings in 
relation to our considerations pursuant to NEPA as well as with regard 
to its general findings for marine mammals. Behavioral disturbance or 
stress may reduce fitness for individual animals and/or may exacerbate 
existing declines in reproductive health and survivorship. For example, 
stressors such as noise and pollutants can induce responses involving 
the neuroendocrine system, which controls reactions to stress and 
regulates many body processes (NAS, 2017). As an example, Romano et al. 
(2004) found that upon exposure to noise from a seismic watergun, 
bottlenose dolphins had elevated levels of a stress-related hormone 
and, correspondingly, a decrease in immune cells. Population-level 
impacts related to energetic effects or other impacts of noise are 
difficult to determine, but the addition of other stressors can add 
considerable complexity due to the potential for interaction between 
the stressors or their effects (NAS, 2017). When a population is at 
risk NAS (2017) recommends identifying those stressors that may 
feasibly be mitigated. In this case, we have done so by prescribing a 
comprehensive suite of mitigation measures that both specifically 
tailors real-time detection and mitigation requirements to the species 
most sensitive to noise from airguns or to additional stressors in 
general (due to overall vulnerability of the stock), and includes 
habitat-based mitigation that restricts survey effort in the areas and 
times expected to be most important for the species at greatest risk of 
more severe impacts from the specified activities (or requires 
comparable protection via other methods).

Acoustic Thresholds

    Comment: NRDC and several other commenters criticized NMFS's use of 
the 160-dB rms Level B harassment threshold, stating that the threshold 
is based on outdated information and that current research shows that 
behavioral impacts can occur at levels below the threshold. Criticism 
of our use of this threshold also focused on its nature as a step 
function, i.e., it assumes animals don't respond to received noise 
levels below the threshold but always do respond at higher received 
levels. Several organizations also suggest that reliance on this 
threshold results in consistent underestimation of impacts. Commenters 
urged the agency to provide additional technical acoustic guidance 
regarding thresholds for behavioral harassment and stated that

[[Page 63285]]

no determinations regarding the proposed IHAs can be made until such 
new guidance has been developed. NRDC specifically stated that NMFS 
should employ specific thresholds for which species-specific data are 
available, and then create generalized thresholds for other species, 
and that the thresholds should be expressed as linear risk functions 
where appropriate to account for intraspecific and contextual 
variability. NRDC and others suggested that NMFS must revise the 
threshold as suggested in Nowacek et al. (2015), which recommended a 
dose function centered on 140 dB rms. TGS suggested that NMFS should 
re-evaluate take estimates using the approach described in Wood et al. 
(2012).
    Response: NMFS acknowledges that the 160-dB rms step-function 
approach is simplistic, and that an approach reflecting a more complex 
probabilistic function may more effectively represent the known 
variation in responses at different levels due to differences in the 
receivers, the context of the exposure, and other factors. Certain 
commenters suggested that our use of the 160-dB threshold implies that 
we do not recognize the science indicating that animals may react in 
ways constituting behavioral harassment when exposed to lower received 
levels. However, we do recognize the potential for Level B harassment 
at exposures to received levels below 160 dB rms, in addition to the 
potential that animals exposed to received levels above 160 dB rms will 
not respond in ways constituting behavioral harassment. These comments 
appear to evidence a misconception regarding the concept of the 160-dB 
threshold. While it is correct that in practice it works as a step-
function, i.e., animals exposed to received levels above the threshold 
are considered to be ``taken'' and those exposed to levels below the 
threshold are not, it is in fact intended as a sort of mid-point of 
likely behavioral responses (which are extremely complex depending on 
many factors including species, noise source, individual experience, 
and behavioral context). What this means is that, conceptually, the 
function recognizes that some animals exposed to levels below the 
threshold will in fact react in ways that are appropriately considered 
take, while others that are exposed to levels above the threshold will 
not. Use of the 160-dB threshold allows for a simplistic quantitative 
estimate of take, while we can qualitatively address the variation in 
responses across different received levels in our discussion and 
analysis.
    NRDC consistently cites reports of changes in vocalization, 
typically for baleen whales, as evidence in support of a lower 
threshold than the 160-dB threshold currently in use. A mere reaction 
to noise exposure does not, however, mean that a take by Level B 
harassment, as defined by the MMPA, has occurred. For a take to occur 
requires that an act have ``the potential to disturb by causing 
disruption of behavioral patterns,'' not simply result in a detectable 
change in motion or vocalization. Even a moderate cessation or 
modification of vocalization might not appropriately be considered as 
being of sufficient severity to result in take (Ellison et al., 2012). 
NRDC claims these reactions result in biological consequences 
indicating that the reaction was indeed a take but does not provide a 
well-supported link between the reported reactions at lower received 
levels and the claimed consequences. In addition, NRDC fails to discuss 
documented instances of marine mammal exposure to received levels 
greater than 160 dB that did not elicit any response. Just a few 
examples are presented here:
     Malme et al. (1985) conducted a study consisting of 
playback using a stationary or moving single airgun and humpback 
whales. No clear overall signs of avoidance of the area were recorded 
for feeding/resting humpback whales exposed to received levels up to 
172 dB. Although startle responses were observed when the airgun was 
first turned on, likely due to the novelty of the sound, increasing 
received levels did not result in increasing probability of avoidance. 
In three instances, whales actually approached the airgun.
     Malme et al. (1988) conducted a controlled exposure 
experiment involving a moving single airgun and gray whales. From this 
study, the authors predicted a 0.5 probability that whales would stop 
feeding and move away from the area when received levels reached 173 dB 
and a 0.1 probability of feeding interruption at a received level of 
163 dB. However, whale responses were highly variable, with some whales 
remaining feeding with received levels as high as 176 dB.
     McCauley et al. (1998, 2000a, 2000b) report observations 
associated with an actual seismic survey (array volume 2,678 in \3\) 
and controlled approaches of humpback whales with a single airgun. When 
exposed to the actual seismic survey, avoidance maneuvers for some 
whales began at a range of 5-8 km from the vessel; however, in three 
trials whales at a range beyond 5 km showed no discernible effects on 
movement patterns. In addition, some male humpback whales were 
attracted to the single airgun (maximum received level of 179 dB). 
Overall, McCauley et al. (2000a) found no gross disruption of humpback 
whale movements in the region of the source vessel, based on encounter 
rates.
     Malme et al. (1983, 1984) conducted playback experiments 
with gray whales involving a single airgun and a full array (2,000-
4,000 in \3\). For playback of the array, it was estimated that 
probability of avoidance during migration (including moving inshore and 
offshore to avoid the area or to pass the noise source at a greater 
distance then would normally occur) was 0.1 at 164 dB; 0.5 at 170 dB; 
and 0.9 at levels greater than 180 dB.
    These examples are related only to baleen whales, for which NRDC 
provides examples of vocalization changes in response to noise 
exposure. Although associated received levels are not available, a 
substantial body of evidence indicates that delphinids are 
significantly more tolerant of exposure to airgun noise. Based on 
review of monitoring reports from many years of airgun surveys, many 
delphinids approach acoustic source vessels with no apparent discomfort 
or obvious behavioral change (Barkaszi et al., 2012; Stone, 2015a). 
Behavioral observations of gray whales during an airgun survey 
monitored whale movements and respirations pre-, during-, and post-
seismic survey (Gailey et al., 2016). Behavioral state and water depth 
were the best `natural' predictors of whale movements and respiration 
and, after considering natural variation, none of the response 
variables were significantly associated with survey or vessel sounds.
    Overall, we reiterate the lack of scientific consensus regarding 
what criteria might be more appropriate. Defining sound levels that 
disrupt behavioral patterns is difficult because responses depend on 
the context in which the animal receives the sound, including an 
animal's behavioral mode when it hears sounds (e.g., feeding, resting, 
or migrating), prior experience, and biological factors (e.g., age and 
sex). Other contextual factors, such as signal characteristics, 
distance from the source, and signal to noise ratio, may also help 
determine response to a given received level of sound. Therefore, 
levels at which responses occur are not necessarily consistent and can 
be difficult to predict (Southall et al., 2007; Ellison et al., 2012; 
Bain and Williams, 2006).
    There is currently no agreement on these complex issues, and NMFS 
followed the practice at the time of submission and review of these 
applications in assessing the likelihood

[[Page 63286]]

of disruption of behavioral patterns by using the 160-dB threshold. 
This threshold has remained in use in part because of the practical 
need to use a relatively simple threshold based on available 
information that is both predictable and measurable for most 
activities. We note that the seminal review presented by Southall et 
al. (2007) did not suggest any specific new criteria due to lack of 
convergence in the data. NMFS is currently evaluating available 
information towards development of guidance for assessing the effects 
of anthropogenic sound on marine mammal behavior. However, undertaking 
a process to derive defensible exposure-response relationships is 
complex (e.g., NMFS previously attempted such an approach, but is 
currently re-evaluating the approach based on input collected during 
peer review of NMFS (2016)). A recent systematic review by Gomez et al. 
(2016) was unable to derive criteria expressing these types of 
exposure-response relationships based on currently available data.
    NRDC consistently cites Nowacek et al. (2015) in public comments, 
suggesting that this paper is indicative of a scientific consensus that 
NMFS is missing or ignoring. We note first that while NRDC refers to 
this paper as a ``study'' (implying that it presents new scientific 
data or the results of new analyses of existing scientific data), the 
paper in fact makes policy recommendations rather than presenting any 
new science. The more substantive reviews presented by Southall et al. 
(2007) and Gomez et al. (2016) were unable to present any firm 
recommendations, as noted above. Other than suggesting a 50 percent 
midpoint for a probabilistic function, Nowacek et al. (2015) offer 
minimal detail on how their recommended probabilistic function should 
be derived/implemented or exactly how this midpoint value (i.e., 140 dB 
rms) was derived (i.e., what studies support this point). In contrast 
with elements of a behavioral harassment function that NRDC indicates 
as important in their comments, Nowacek et al. (2015) does not make 
distinctions between any species or species groups and provide no 
quantitative recommendations for acknowledging that behavioral 
responses can vary by species group and/or behavioral context. In 
summary, little substantive support is provided by Nowacek et al. 
(2015) for the proposal favored by NRDC and it is treated in that paper 
as a vague recommendation with minimal support offered only in a one-
page supplementary document rather than well-supported scientific 
consensus, as the commenter suggests.
    NMFS disagrees that establishing species-specific thresholds is 
practical (i.e., this approach would make assessments unnecessarily 
onerous by creating numerous thresholds to evaluate). Additionally, 
there is scientific evidence that grouping thresholds by broad source 
category (Gomez et al., 2016) or taxonomic group (NMFS, 2018) is 
supportable. NMFS currently uses data/thresholds from surrogate 
species/groups to represent those species/groups where data are not 
available.
    Overall, while we agree that there may be methods of assessing 
likely behavioral response to acoustic stimuli that better capture the 
variation and context-dependency of those responses than the simple 
step-function used here, there is no agreement on what that method 
should be or how more complicated methods may be implemented by 
applicants. NMFS is committed to continuing its work in developing 
updated guidance with regard to acoustic thresholds, but pending 
additional consideration and process is reliant upon an established 
threshold that is reasonably reflective of available science.
    In support of exploring new methods for quantitatively predicting 
behavioral harassment, we note NMFS's recently published proposed 
incidental take regulations for geophysical surveys in the Gulf of 
Mexico (83 FR 29212; June 22, 2018), which propose using the modeling 
study first published in BOEM's associated EIS (Appendix D in BOEM, 
2017) to estimate take. This study evaluated potential disruption of 
behavioral patterns that could result from a program of airgun surveys, 
using both the 160-dB step function and a probabilistic risk function 
similar to that suggested by Nowacek et al. (2015), but with a midpoint 
set at 160 dB for the majority of species, rather than 140 dB. This 
function, described in Wood et al. (2012), includes for most species a 
10 percent probability of behavioral harassment at 140 dB, with 
subsequent steps of 50 percent at 160 dB and 90 percent at 180 dB. Of 
note, use of this generic function resulted in lower numbers of 
estimated takes than did use of the 160-dB step function. Therefore, 
while use of the probabilistic risk function may allow for more 
specific quantitative consideration of contextual issues and variation 
in individual responses, our use of the 160-dB step function is 
conservative in that the number of resulting takes is higher. NMFS will 
continue to explore quantitative refinement of the behavioral 
harassment threshold where there is available information to support 
methodologies that better reflect the variation in individual 
responses. However, the current threshold allows for an appropriate, 
and often conservative, enumeration of predicted takes by Level B 
harassment, which support robust negligible impact and small numbers 
analyses.
    Comment: Nowacek et al. stated that use of the 160-dB threshold 
would be specifically problematic for beaked whales, as these species 
demonstrate behavioral response at levels below 160 dB rms and occupy 
certain areas of the specific geographic region in high densities.
    Response: Please see our previous comment response regarding use of 
the 160-dB threshold for behavioral harassment. With regard to the 
expected significance of takes by harassment specifically for beaked 
whales, we acknowledge that beaked whales are documented as being a 
particularly behaviorally sensitive species in response to noise 
exposure. This information is considered in our negligible impact 
analyses (``Negligible Impact Analyses and Determinations'') and 
informed our evaluation of the mitigation necessary to satisfy the 
least practicable adverse impact standard (``Mitigation''). We require 
implementation of three year-round closures of submarine canyon areas 
expected to provide important habitat for beaked whales, a seasonal 
closure of the area off of Cape Hatteras cited by the commenters, and 
have required expanded shutdown requirements for beaked whales. 
Additionally, regarding the specific levels at which they are 
behaviorally harassed by exposure to noise from airguns, we note that 
there are no data on beaked whale responses to airgun noise, and their 
hearing sensitivity in the frequency range of signals produced by 
airguns is notably lower than their sensitivity in the frequency range 
of the sonar sources for which data is available indicating that they 
have responded at lower levels (in other words, noise from an airgun 
must be louder than a sonar pulse for them to hear it as the same 
level).
    Comment: NRDC and others stated that if NMFS does not revise 
existing behavioral harassment thresholds, it should use the acoustic 
threshold for continuous noise (i.e., 120 dB rms) rather than the 
threshold for intermittent sound sources (i.e., 160 dB rms). NRDC 
contends that, as a result of reverberation and multipath arrivals, the 
impulsive signal produced by airguns is more similar to a continuous 
noise at greater distances from the source and,

[[Page 63287]]

therefore, use of the 120-dB ``continuous'' noise threshold is more 
appropriate than the 160-dB threshold for intermittent sound sources.
    Response: NMFS acknowledges that as airgun shots travel through the 
environment, pulse duration increases because of reverberation and 
multipath propagation. However, we disagree that the 120-dB rms 
threshold for continuous noise--which was based on behavioral responses 
of baleen whales to drilling (Malme et al., 1984; Richardson et al., 
1990)--is more appropriate than the intermittent noise threshold of 
160-dB rms for evaluating potential behavioral harassment resulting 
from airgun noise. The 160-dB threshold was derived from data for 
mother-calf pairs of migrating gray whales (Malme et al., 1983, 1984) 
and bowhead whales (Richardson et al., 1985, 1986) behaviorally 
responding when exposed specifically to noise from airguns. The 
Richardson et al. (1985, 1986) studies included controlled approaches 
with a full-scale airgun array firing at 7.5 km from the animals. Thus, 
behavioral responses observed in these studies account for changes in 
the pulse duration associated with propagation.
    In addition, there is a prevalent misconception in comments from 
NRDC and others regarding Level B harassment, as defined by the MMPA. 
NRDC cites multiple observations of behavioral reactions or of changes 
in vocal behavior in making statements supporting their overall 
recommendation that behavioral harassment thresholds be lower. However, 
these observations do not necessarily constitute evidence of disruption 
of behavioral patterns (Level B harassment) rather than simple 
reactions to often distant noise, which may provoke a reaction when 
discernable above ambient noise levels.
    For example, changes in mysticete vocalization associated with 
exposure to airgun surveys within migratory and non-migratory contexts 
have been observed (e.g., Castellote et al., 2012; Blackwell et al., 
2013; Cerchio et al., 2014). The potential for these changes to occur 
over large spatial scales is not surprising for species with large 
communication spaces, like mysticetes (e.g., Clark et al., 2009), 
although not every change in a vocalization would necessarily rise to 
the level of a take.
    Comment: NRDC claims that NMFS misapplies the MMPA's statutory 
definition of harassment by adopting a probability standard other than 
``potential'' in setting thresholds for auditory injury, stating that a 
take estimate based on ``potential'' should either count take from the 
lowest exposure level at which hearing loss can occur or establish a 
probability function that accounts for variability in the acoustic 
sensitivity of individual marine mammals. Instead, NRDC states that 
NMFS derived auditory injury thresholds from average exposure levels at 
which tested marine mammals experience hearing loss, which discounts 
instances of hearing loss at lower levels of exposure. The comment goes 
on to state that for purposes of take estimation, thresholds based on 
mean or median values will lead to roughly half of an exposed cohort 
experiencing the impacts that the threshold is designed to avoid, at 
levels that are considered ``safe,'' therefore resulting in substantial 
underestimates of auditory injury. NRDC makes similar statements with 
regard to the 160-dB threshold for Level B harassment.
    Response: The technical guidance's (NMFS, 2018) onset thresholds 
for temporary threshold shift (TTS) for non-impulsive sounds encompass 
more than 90 percent of available TTS data (i.e., for mid-frequency 
cetaceans, only two data points are below the onset threshold, with 
maximum point only 2 dB below), and in some situations 100 percent of 
TTS data (e.g., high-frequency cetaceans; although this group is data-
limited). Thus, the technical guidance thresholds provide realistic 
predictions, based on currently available data, of noise-induced 
hearing loss in marine mammals. For impulsive sounds, data are limited 
to two studies, and NMFS directly adopted the TTS onset levels from 
these two studies for the applicable hearing groups.
    Our Federal Register notice announcing the availability of the 
original technical guidance (81 FR 51694; August 4, 2016; NMFS, 2016), 
indicated that onset of auditory injury (PTS) equates to Level A 
harassment under the MMPA. We explained in that notice that because the 
acoustic thresholds for PTS conservatively predict the onset of PTS, 
they are inclusive of the ``potential'' language contained in the 
definition of Level A harassment. See 81 FR 51697, 51721.
    Regarding Level B harassment, based on the language and structure 
of the definition of Level B harassment, we interpret the concept of 
``potential to disturb'' as embedded in the assessment of the 
behavioral response that results from an act of pursuit, torment, or 
annoyance (collectively referred to hereafter as an ``annoyance''). The 
definition refers to a ``potential to disturb'' by causing disruption 
of behavioral patterns. Thus, an analysis that indicates a disruption 
in behavioral patterns establishes the ``potential to disturb.'' A 
separate analysis of ``potential to disturb'' is not needed. In the 
context of an authorization such as this, our analysis is forward-
looking. The inquiry is whether we would reasonably expect a disruption 
of behavioral patterns; if so, we would conclude a potential to disturb 
and therefore expect Level B harassment. We addressed NRDC's concerns 
regarding the scientific support for the Level B harassment threshold 
in a previous comment response.
    Comment: The Center for Regulatory Effectiveness (CRE) does not 
agree with NMFS's use of the technical acoustic guidance (NMFS, 2016, 
2018) for purposes of evaluating potential auditory injury. CRE claims 
that (1) NMFS's use of the guidance conflicts with Executive Order 
13795 (``Implementing an America-First Offshore Energy Strategy''); (2) 
the guidance violates the Office of Management and Budget's (OMB) Peer 
Review Bulletin and Guidance Document Bulletin and implementing 
Memoranda; (3) violates Information Quality Act (IQA) guidelines; and 
(4) violates Executive Orders 12866 (``Regulatory Planning and 
Review'') and 13771 (``Reducing Regulation and Controlling Regulatory 
Costs''). Regarding the IQA, CRE states that NMFS does not have an OMB-
approved Information Collection Request (ICR) associated with the 
guidance, and is therefore violating the IQA. The CRE also claims that 
NMFS's use of the guidance violates the MMPA requirement that all 
mitigation requirements be practicable, as the guidance supposedly 
requires monitoring and reporting requirements and other mitigation 
requirements that are impossible to comply with.
    Response: NMFS disagrees that use of the technical guidance results 
in any of the claims listed by CRE. First, the use of the technical 
guidance does not conflict with Executive Order 13795. Section 10 of 
the Executive Order called for a review of the technical guidance 
(NMFS, 2016) as follows: ``The Secretary of Commerce shall review for 
consistency with the policy set forth in Section 2 of this order and, 
after consultation with the appropriate Federal agencies, take all 
steps permitted by law to rescind or revise that guidance, if 
appropriate.'' To assist the Secretary in the review of the technical 
guidance, NMFS solicited public comment via a 45-day public comment 
period (82 FR 24950; May 31, 2017) and hosted an interagency 
consultation meeting with representatives from ten federal agencies 
(September 25, 2017). NMFS

[[Page 63288]]

provided a summary of comments and recommendations received during this 
review to the Secretary, and per the Secretary's approval, issued a 
revised version of the technical guidance in June 2018 (83 FR 28824; 
NMFS, 2018).
    Second, NMFS did comply with the OMB Peer Review Bulletin and IQA 
Guidelines in development of the technical guidance. The technical 
guidance was classified as a Highly Influential Scientific Assessment 
and, as such, underwent three independent peer reviews, at three 
different stages in its development, including a follow-up to one of 
the peer reviews, prior to its dissemination by NMFS. In addition, 
there were three separate public comment periods. Responses to public 
comments were provided in a previous Federal Register notice (81 FR 
51694; August 4, 2016). Detailed information on the peer reviews and 
public comment periods conducted during development of the guidance are 
included as an appendix to the guidance, and are detailed online at: 
www.cio.noaa.gov/services_programs/prplans/ID43.html.
    Furthermore, the technical guidance is not significant for purposes 
of Executive Orders 12866 or 13771 or OMB's Bulletin entitled, ``Agency 
Good Guidance Practices'' for significant guidance documents. 72 FR 
3432 (January 25, 2007). Nevertheless, the technical guidance follows 
the practices and includes disclaimer language suggested by the OMB 
Bulletin to communicate effectively to the public about the legal 
effect of the guidance. Finally, with regard to the claim that NMFS's 
use of the technical guidance violates the MMPA requirement that all 
mitigation requirements be practicable, as the guidance supposedly 
requires monitoring and reporting requirements and other mitigation 
requirements that are impossible to comply with, we reiterate that 
mitigation and monitoring requirements associated with an MMPA 
authorization or ESA consultation or permit are independent management 
decisions made in accordance with statutory and regulatory standards in 
the context of a proposed activity and comprehensive effects analysis 
and are beyond the scope of the technical guidance. The technical 
guidance does not mandate mitigation or monitoring. Finally, there is 
no collection of information requirement associated with the technical 
guidance, so no ICR is required.
    Comment: Several groups raised concerns regarding use of the 
technical acoustic guidance (NMFS, 2016, 2018), claiming that the 
guidance is not based on the best available science and underestimates 
potential auditory injury. NRDC specifically cited many supposed issues 
with the guidance, including adoption of ``erroneous'' models, broad 
extrapolation from a small number of individuals, and disregarding 
``non-linear accumulation of uncertainty.'' NRDC suggests that NMFS 
retain the historical 180-dB rms Level A harassment threshold as a 
``conservative upper bound'' or conduct a ``sensitivity analysis'' to 
``understand the potential magnitude'' of the supposed errors. Oceana 
stated that NMFS should not make a decision about the proposed IHAs 
while the technical guidance is under review.
    Response: The original 2016 technical guidance and revised 2018 
guidance is a compilation, interpretation, and synthesis of the 
scientific literature that provides the best available information 
regarding the effects of anthropogenic sound on marine mammals' 
hearing. The technical guidance was classified as a Highly Influential 
Scientific Assessment and, as such, underwent three independent peer 
reviews, at three different stages in its development, including a 
follow-up to one of the peer reviews, prior to its dissemination by 
NMFS. In addition, there were three separate public comment periods, 
during which time we received and responded to similar comments on the 
guidance (81 FR 51694), and more recent public and interagency review 
under Executive Order 13795. While new information may help to improve 
the guidance in the future, and NMFS will review the available 
literature to determine when revisions are appropriate, the final 
guidance reflects the best available science and all information 
received through peer review and public comment. Given the systematic 
development of the guidance, which was also reviewed multiple times by 
both independent peer reviewers and the public, NRDC's use of the 
phrase ``arbitrary and capricious'' is unreasonable.
    The guidance updates the historical 180-dB rms injury threshold, 
which was based on professional judgement (i.e., no data were available 
on the effects of noise on marine mammal hearing at the time this 
original threshold was derived). NMFS does not believe the use of the 
technical guidance provides erroneous results. The 180-dB rms threshold 
is plainly outdated, as the best available science indicates that rms 
SPL is not even an appropriate metric by which to gauge potential 
auditory injury (whereas the scientific debate regarding behavioral 
harassment thresholds is not about the proper metric but rather the 
proper level or levels and how these may vary in different contexts). 
NRDC's advice to return to use of the 180-dB threshold is inconsistent 
with its criticism of the 160-dB rms criterion for Level B harassment. 
However, as we said in responding to comments criticizing the Level B 
harassment criterion, development of an updated threshold(s) is 
complicated by the myriad contextual and other factors that must be 
considered and evaluated in reaching appropriate updated criteria. See 
our response to comment on the Level B harassment threshold.

Sound Field Modeling

    Comment: The MMC noted differences in the estimated Level B 
harassment radii provided in ION and Spectrum's applications, noting 
that since the largest discrepancies were observed at shallow water 
sites, it is likely that geoacoustic properties were responsible. 
Although both ION and Spectrum used sediment data from cores collected 
during the Ocean Drilling Program, the data was based on samples from 
different sites and potentially different assumptions as to sediment 
attenuation. The MMC provided related recommendations: (1) NMFS should 
determine whether ION's or Spectrum's estimated zones are the most 
appropriate and require that both companies use the same set of zones; 
(2) NMFS should require each of the five companies to conduct sound 
source verification (SSV) in waters less than 100 m and use that data 
to inform and adjust the extent of Level B harassment zones as 
necessary; and (3) NMFS should determine the appropriate baseline 
geoacoustic model for the region in concert with BOEM, ION, and 
Spectrum, and then require this in future IHAs for similar activities 
in the region.
    Response: NMFS appreciates the MMC's attention to this matter, but 
disagrees that it is necessarily appropriate to require use of the same 
data or approaches to modeling sound fields when there is not clearly a 
``most appropriate'' approach. Sound field modeling for both ION and 
Spectrum was conducted by experts in the field. We appropriately 
approved both applicants' applications as adequate and complete, 
determining that both used appropriate data inputs and acceptable 
modeling approaches. Subsequently, both applications were made 
available for public review in order to better inform NMFS's 
preparation of proposed IHAs; no such concerns were raised. 
Importantly, we recognize that there is no model or approach that is 
always the most appropriate and that there may be multiple approaches 
that may be

[[Page 63289]]

considered acceptable. Having determined that both applicants used 
appropriate data and acceptable modeling approaches, it would be 
inappropriate to require one to change their approach to conform to the 
other because of differences in the results. Given our confidence in 
the data inputs and modeling approaches used, we find that a 
requirement to conduct SSV studies is not warranted, despite 
discrepancies in modeling results. As is appropriate, NMFS would 
consider the appropriateness of data inputs and modeling approaches for 
any future applications but, in keeping with our response here, will 
not necessarily enforce use of one dataset or modeling approach when 
others may be considered as equally representative of the best 
available scientific data and techniques.
    Comment: One individual suggested that, because the representative 
airgun array used in BOEM's sound field modeling was characterized as 
having a source level lower than that of arrays planned for use by the 
applicants, use of BOEM's sound field modeling could lead to an 
underestimate of takes.
    Response: Numerous factors combine in the sound field modeling 
provided by BOEM to result ultimately in estimates of sound fields at 
different locations. BOEM's modeling was performed to be reasonably 
representative of the types of sources that would be used in future 
surveys, recognizing that actual sources may vary somewhat from what 
was considered in the sound field modeling. We disagree that these 
minor differences would have meaningful impacts on the ultimate result 
of the exposure estimation process, and find that the modeling provided 
by BOEM was reasonably representative of what would occur during actual 
surveys and, therefore, acceptable to use for informing the take 
estimates for these surveys.
    Comment: One individual stated that NMFS does not fully consider 
the implications of different weather phenomena in acoustic 
propagation, and that in failing to account for variations in ocean and 
weather conditions, the average estimates of propagation and take are 
biased downward. The same individual also claimed that NMFS did not 
adequately consider ocean floor sediment composition in modeling 
expected sound fields, and states again that this would likely result 
in higher numbers of take.
    Response: While NMFS acknowledges that discrete weather phenomena 
could result in propagation being more or less efficient than 
anticipated under a seasonal average scenario (i.e., one element of 
propagation modeling is the use of sound velocity profiles that are 
season-specific within the specific geographic region), the commenter 
provides no basis for concluding that such phenomena would lead overall 
to the estimated takes being biased downward. Further, the sound field 
modeling approaches taken by the applicants (and in BOEM's PEIS) follow 
state-of-science approaches and are reasonable when considering the 
need to model propagation year-round and over a wide geographic area. 
The commenter provides no specific recommendation for how the 
suggestion should be accomplished. With regard to sediment composition, 
the applicants' sound field modeling considered sediment 
characteristics at 15 representative modeling sites throughout the 
region, and the commenter does not provide any evidence to back the 
claim that variability in actual sediment composition would result in 
bias to take estimates in a particular direction or provide any 
specific recommendation to remedy the perceived flaw.
    Comment: Ocean Conservation Research (OCR) noted that NMFS did not 
consider a secondary transmission path in the mixed layer above the 
marine thermocline that behaves as a surface duct, stating that, while 
the propagation in this transmission path is dependent on the 
wavelength of the source, the angle of incidence, the depth of the 
mixed layer, and the surface conditions, the attenuation 
characteristics are more consistent with the cylindrical spreading 
model. OCR goes on to claim that, assuming cylindrical propagation of 
surface ducted noise, typical airgun noise would require 13 km to 
attenuate to a received level of 180 dB rms.
    Response: Although OCR is correct to point out that the mechanism 
of sound propagation is complex in the ocean environment, with the 
potential formation of a surface duct as a result of the mixed layer 
above the permanent thermocline, the conclusion derived by OCR that 
typical airgun noise would require 13 km to attenuate to a received 
level of 180 dB rms is unsupported.
    First, oceanographic conditions in the mid-Atlantic region do not 
support a persistent surface duct, which usually occurs after a storm 
or consistently cool and windy weather. A reduction of surface wind 
velocity and the warming of the surface water will quickly break down a 
surface duct and cause the downward refraction of a shallow source 
(e.g., source from an airgun array) due to a negative sound velocity 
profile above the thermocline.
    Second, as stated above, the formation of a surface duct requires 
strong wind gusts and a high sea state, which are not ideal conditions 
for conducting a seismic survey given the need to tow a large array of 
airguns and long streamers. Thus, even if a surface duct is formed, it 
is very unlikely that a seismic survey would continue under such 
conditions.
    Third--as OCR correctly pointed out--sound propagation in a surface 
duct is dependent on the wavelength of the source, the angle of 
incidence, the depth of the mixed layer, and the surface conditions. 
Among these parameters, the depth of the mixed layer is typically 
determined by the wind speed and sea state. While relatively low wind 
speed may support a weak, shallow surface duct, such a duct cannot 
support propagation of airgun sound, which is predominantly low-
frequency. Jensen et al. (2011) provide the following equation that 
determines the cutoff frequency (frequency below which sound will not 
propagate) given the depth of an isothermal surface layer:
[GRAPHIC] [TIFF OMITTED] TN07DE18.001

where f0 is the cutoff frequency in Hz and D is the depth in 
meters of an isothermal surface layer. As an example, for a cutoff 
frequency to be around 100 Hz, the surface duct needs to be at least 
150 m deep. In general, shallow ducts (D <50 m) are more common, but 
they are only effective waveguides for frequencies above 530 Hz, which 
also suffer high scattering loss due to the rough sea surface under 
these weather conditions.
    Finally, most acoustic rays from an airgun array are emitted at 
very steep angles to be contained within the surface duct waveguide.
    For these reasons, we do not believe surface ducts in the mid-
Atlantic region, if they exist, would contribute noticeably to 
propagation for sound emitted from airguns.
    Comment: NRDC stated that NMFS used unrealistic and non-
conservative assumptions about spreading loss, bottom composition, and 
reverberation in its propagation analysis and claimed that the analysis 
does not represent the best available science. NRDC stated that, for 
propagation loss, NMFS incorrectly assumed that normal propagation 
conditions would apply, such as not accounting for surface ducting (and 
BOEM only assumed moderate surface ducting in 3 of 21 modeled areas). 
Furthermore, NRDC stated that low-

[[Page 63290]]

frequency propagation along the seabed can spread in a planar manner, 
and can propagate with more efficiency than indicated by cylindrical 
propagation. Finally, NRDC asserted that NMFS cannot accept the 
assumptions in three applications (CGG, TGS, and WesternGeco) that 
proposed surveys will cover areas with soft or sandy bottoms. NRDC 
claims that NOAA's own models indicate that there is a likelihood of 
coral bottom habitat in the survey area, and many hard-bottom habitat 
areas were not modeled by BOEM and consequently incorporated by NMFS.
    Response: Regarding sound propagation in a surface duct, please 
refer to the above response to a similar comment from OCR. As stated 
earlier, oceanographic conditions in the mid-Atlantic region do not 
support a persistent surface duct, particularly for low-frequency sound 
propagation. Therefore, the modeling of a moderate surface duct for 
airgun noise propagation is a conservative measure. Also as stated 
earlier, frequency and launch angle of the source play a major role in 
surface ducting. This information is clearly stated by D'Spain et al. 
(2006) with regard to the 2000 beaked whale stranding in the Bahamas, 
i.e., that the surface duct ``. . . effectively traps mid to high 
frequency sound radiated by acoustic sources within the duct, such as 
surface ship sonars . . .'' and that ``[a]t low frequencies, the sound 
is no longer effectively trapped by the duct because the acoustic 
wavelength. . . . is too large in comparison to the duct thickness.''
    NRDC's statement that ``low-frequency propagation along the seabed 
can spread in a planar manner . . . can propagate with significantly 
greater efficiency than cylindrical propagation would indicate'' is 
incorrect. Any acoustic wave can be approximated for plane wave 
propagation at sufficiently far range (R) for a region (W) such that W 
<= ([lambda]R)1/2, where [lambda] is the wavelength. This 
plane wave approximation has no bearing on the efficiency of sound 
propagation.
    Finally, substrate types for propagation modeling are based on 
grain size, porosity, and shear velocity, etc., and ``coral bottom'' is 
not one of them. In fact, the roughness of the coral habitat would 
cause severe bottom loss due to scattering. Based on published 
literature, bottom types of the region are mostly composed of sand 
(e.g., Stiles et al., 2007; Kaplan, 2011). Therefore, the use of sand 
and clay for propagation modeling is appropriate. The acoustic modeling 
provided by BOEM (2014a) appropriately and reasonably accounts for 
variability in bottom composition throughout the planned survey area.
    Comment: Some groups noted that the different approaches taken to 
acoustic modeling make it difficult to compare takes. Specifically, 
TGS, CGG, and Western relied on the acoustic modeling provided in 
BOEM's PEIS, while ION and Spectrum performed their own modeling. In 
addition, Spectrum and ION used a restricted suite of sound velocity 
profiles, matching the seasons when they intend to conduct their 
planned surveys. The comment letter from Nowacek et al. adds an 
assertion that this difficulty in comparing takes is problematic when 
NMFS is trying to assess whether the activities impact only small 
numbers or cause negligible impacts, and state that they ``can find no 
evidence in the Notice that NMFS took account of these significant 
problems when attempting to evaluate the impacts of the IHAs.''
    Response: As stated in a previous response to an MMC comment, NMFS 
disagrees that the different approaches taken to sound field modeling 
constitute a problem at all, much less a significant one. BOEM's PEIS 
provides a sound analysis of expected sound fields in a variety of 
propagation conditions, including water depth, bottom type, and season, 
for a representative airgun array. ION and Spectrum conducted similar 
sound field modeling, but with the added advantage of modeling the 
specific array planned for use and limiting use of sound velocity 
profiles to the time period when the survey is planned to occur. No 
commenter provided any rational basis for disputing that these methods 
are appropriate or that they used the best available information and 
modeling processes. Regardless of differences in the sound field 
modeling processes, one would not expect that the take estimates are 
directly comparable, precisely because the surveys are planned for 
different locations, using different sound sources, and, for some 
companies, operating at different times of year. We disagree the 
various modeling approaches cause some problem for conducting 
appropriate negligible impact and/or small numbers analyses; both of 
these findings are appropriately made in consideration of a given 
specified activity. Therefore, comparison of the take numbers across 
IHAs is not a relevant consideration. We disagree that differences in 
approaches across the applications are arbitrary. On the contrary, we 
carefully evaluated each applicant's approaches to take estimation and, 
while they are indeed different in some respects, each applicant uses 
accepted approaches. Unlike NRDC, we recognize that there is no model 
or approach that is always the most appropriate and that there may be 
multiple approaches that may be considered acceptable. Far from 
``parroting'' the applicants' assessments, as NRDC implies, NMFS made 
substantial changes where necessary, including complete revision of 
North Atlantic right whale take estimates for all applicants, revision 
of take estimates for all species using the best available density data 
(i.e., Roberts et al., 2016) for ION and Spectrum, and revised 
assessment of potential Level A harassment for all applicants. NMFS 
strongly disagrees that ``grossly inconsistent'' data or methods were 
used for any applicant in the analyses described herein.
    Comment: One individual noted that it is not apparent how NMFS 
accounted for high-frequency sounds, which has implications for 
potential takes by Level A harassment for species that hear better at 
higher frequencies. The commenter wrote that airguns produce pulses 
with most energy at low frequencies (around 10 Hz), but that these 
pulses contain significant energy at frequencies up to more than 100 
kHz, claiming that high-frequency hearing specialists can be affected 
at distances of 70 km or more. The commenter cited Bain and Williams 
(2006) in support of the latter claim.
    Response: In considering the potential impacts of higher-frequency 
components of airgun noise on marine mammal hearing, one needs to 
account for energy associated with these higher frequencies and 
determine what energy is truly ``significant.'' Tolstoy et al. (2009) 
conducted empirical measurements, demonstrating that sound levels 
(i.e., one-third-octave and spectral density) associated with airguns 
were at least 20 dB lower at 1 kHz compared to higher levels associated 
with lower frequencies (below 300 Hz). These levels were even lower at 
higher frequencies beyond 1 kHz. Thus, even though high-frequency 
cetaceans may be more susceptible to noise-induced hearing loss at 
higher frequencies, it does not mean that a source produces a 
sufficiently loud sound at these higher frequencies to induce a PTS 
(i.e., auditory injury). For example, Bain and Williams (2006) 
indicated ``airguns produced energy above ambient levels at all 
frequencies up to 100 kHz (the highest frequency measured), although 
the peak frequency was quite low.'' However, a finding that airgun 
signals contain energy ``above ambient'' and are detectable at 
frequencies up to 100 kHz does not mean that these levels are high 
enough to result in auditory injury. The commenter does not describe 
what is

[[Page 63291]]

meant by ``significant'' energy, but there is no information to suggest 
that these higher-frequency noise components are sufficient to cause 
auditory injury at ranges beyond those described in Table 5.
    Furthermore, Bain and Williams (2006) focus on behavioral responses 
of marine mammals to airgun surveys, rather than on potential impacts 
on hearing. Harbor porpoises, while considered a high-frequency 
cetacean in terms of hearing, are also often categorized as a 
particularly sensitive species behaviorally (i.e., consistently 
responds at a lower received level than other species; Southall et al., 
2007). We agree that harbor porpoises are more likely to avoid loud 
sound sources, such as airgun arrays, at greater distances. However, 
this means that these species are even less likely to incur some degree 
of threshold shift.

Marine Mammal Densities

    Comment: The MMC recommended that NMFS require TGS and Western to 
use the Roberts et al. (2016) model, rather than the approach described 
herein (see ``Estimated Take''). MMC describes several perceived 
problems with the approach taken by TGS and Western, including that 
they do not adequately account for availability and detection biases, 
and that their approach does not use the same habitat-based approach to 
predicting density. Overall, they state that it does not make sense for 
applicants to use different density estimates for the same area.
    Response: Please see ``Estimated Take'' for a full description of 
take estimation methodologies used by TGS and Western. First, we note 
that the applicants did carefully consider the Roberts et al. data in 
addition to other available sources of data. In fact, these two 
applicants did use the Roberts et al. data for a group of nine species, 
while devising an alternate methodology for a separate group of seven 
species that did not meet a specific threshold for sightings data 
recommended by Buckland et al. (2001). Further, these applicants did 
account for bias, correcting densities using general g(0) values for 
aerial and vessel surveys for each species as published in the 
literature.
    As stated below and in our Notice of Proposed IHAs, we determined 
that their alternative approach (for seven species or species groups) 
is acceptable. We recognize that there is no model or approach that is 
always the most appropriate and that there may be multiple approaches 
that may be considered acceptable. The alternative approach used for 
seven species actually uses the most recent data, and does so in a way 
that conforms with recommended methods for deriving density values from 
sightings data. We do not believe that one or the other approach is 
non-representative of the best available science and methodologies.
    Comment: NRDC criticized NMFS's use of the Roberts et al. (2016) 
model outputs for purposes of deriving abundance estimates, as used in 
NMFS's small numbers analyses. NRDC states that we should use the NMFS 
Stock Assessment Report (SAR) abundance estimates for this purpose, 
while allowing that model-predicted abundance estimates may be used for 
``data-deficient'' stocks. NRDC implies that use of model-predicted 
abundances would overestimate actual abundances, apparently based on 
the fact that the density models are informed by many years of data 
rather than only the most recent year of data. Where model-predicted 
abundance estimates are used, NRDC recommends that we adjust the 
averaged model outputs to the lower bound of the standard deviation 
estimated by the model for each grid cell.
    Response: The approach recommended by NRDC is plainly 
inappropriate. Comparing take estimates generated through use of the 
outputs of a density model to an unrelated abundance estimate provides 
a meaningless comparison. As explained in our Notice of Proposed IHAs, 
in most cases we compare the take estimates generated through use of 
the density outputs to the abundance predicted through use of the model 
precisely to provide a meaningful comparison of predicted takes to 
predicted population. To illustrate this, we provide the extreme 
example of the Gulf of Mexico stock of Clymene dolphin. NMFS's three 
most recent SAR abundance estimates for this stock have fluctuated 
between 129 and 17,355 animals, i.e., varying by a maximum factor of 
more than 100. For most species, such fluctuations across these 
``snapshot'' abundance estimates (i.e., that are based on only the most 
recent year of survey data) reflect interannual variations in dynamic 
oceanographic characteristics that influence whether animals will be 
seen when surveying in predetermined locations, rather than any true 
increase or decline in population abundance. In fact, NMFS's SARs 
typically caution that trends should not be inferred from multiple such 
estimates, that differences in temporal abundance estimates are 
difficult to interpret without an understanding of range-wide stock 
abundance, and that temporal shifts in abundance or distribution cannot 
be effectively detected by surveys that only cover portions of a 
stock's range (i.e., U.S. waters). The corresponding density model for 
Gulf of Mexico Clymene dolphins predicts a mean abundance of 11,000 
dolphins. Therefore, in this example, NRDC would have us compare takes 
predicted by a model in which 11,000 dolphins are assumed to exist to 
the most recent (and clearly inaccurate) abundance estimate of 129 
dolphins. Our goal in assessing predicted takes is to generate a 
meaningful comparison, which is accomplished in most cases through use 
of the model-predicted abundance.
    SAR abundance estimates have other issues that compromise their use 
in creating meaningful comparisons here. As in the example above, use 
of multiple years of data in developing an abundance estimate minimizes 
the influence of interannual variation in over- or underestimating 
actual abundance. Further, SAR abundance estimates are typically 
underestimates of actual abundance because they do not account for 
availability bias due to submerged animals--in contrast, Roberts et al. 
(2016) do account for availability bias and perception bias on the 
probability of sighting an animal--and because they often do not 
provide adequate coverage of a stock's range. The SAR for the Canadian 
East Coast stock of minke whales provides an instructive example of the 
latter. In the 2015 SARs, NMFS presented a best abundance estimate of 
20,741 minke whales, reflecting data that provided adequate (but not 
complete) coverage of the stock's range. In the 2016 SARs, NMFS claims 
an abundance estimate of 2,591 whales for this same stock (albeit with 
caveats) simply because the survey data covering the Canadian portion 
of the range was no longer included in determining the best abundance 
estimate. We assume that again, based on this comment, NRDC would have 
us compare the minke whale take estimates to this plainly incomplete 
abundance estimate.
    NRDC appears to claim that the SARs are an appropriate 
representation of ``actual'' abundance, whereas the Roberts et al. 
(2016) predictions are not. NRDC also appears to claim, without 
substantiation, that an abundance estimate derived from multiple years 
of data would typically overestimate actual abundance. However, these 
estimates are not directly comparable--not because one represents a 
``snapshot,'' while one represents multiple years of data, but because 
one does not correct for one or more known biases against the 
probability of observing animals

[[Page 63292]]

during survey effort, while the other does. Because of this important 
caveat, NMFS's SAR abundance estimates should not be considered 
``actual'' abundance more than any other accepted estimate. Therefore, 
when multiple estimates of a stock's abundance are available, they 
should be evaluated based on quality, e.g., does the estimate account 
for relevant biases, does it best cover the stock's range, does it 
minimize the effect of interannual variability, and, importantly, 
should provide a meaningful comparison. In summary, NRDC's comment 
reflects an inaccurate interpretation of the available information, and 
NMFS strongly disagrees with the recommended approach.

Take Estimates

    Comment: The Associations (representing oil and gas industry 
interests) state that ``NMFS substantially overestimates the number of 
incidental takes predicted to result'' from the specified activities. 
The comment goes on to discuss the ``biased modeling that is 
intentionally designed to overestimate take'' provided in BOEM's 2014 
PEIS. Other industry commenters repeat these points verbatim.
    Response: The Associations' statement that NMFS has substantially 
overestimated takes is incorrect. First, in large part the take 
estimates are those presented by the applicants (although in some cases 
NMFS has made changes to the presented estimates in accordance with the 
best available information). Second, two applicants conducted their own 
independent sound field modeling, which NMFS accepted. In fact, BOEM 
and these two applicants followed best practices and used the best 
available information in conducting state-of-the-science sound field 
modeling. The Associations' complaints include no substantive 
recommendations for improvement.
    NMFS participated in development of the acoustic modeling through 
its status as a cooperating agency in development of BOEM's PEIS. We 
strongly disagree with the Associations' characterization of the 
modeling conducted by BOEM and with the BOEM statements cited by the 
Associations. While the modeling required that a number of assumptions 
and choices be made by subject matter experts, some of these are 
purposely conservative to minimize the likelihood of underestimating 
the potential impacts on marine mammals represented by a specified 
level of survey effort. The modeling effort incorporated representative 
sound sources and projected survey scenarios (both based on the best 
available information obtained by BOEM), physical and geological 
oceanographic parameters at multiple locations within U.S. waters of 
the mid- and south Atlantic and during different seasons, the best 
available information regarding marine mammal distribution and density, 
and available information regarding known behavioral patterns of the 
affected species. Current scientific information and state-of-the-art 
acoustic propagation and animal movement modeling were used to 
reasonably estimate potential exposures to noise. NMFS's position is 
that the results of the modeling effort represent a conservative but 
reasonable best estimate. These comments provide no reasonable 
justification as to why the modeling results in overestimates of take, 
instead seemingly relying on the mistaken notion that real-time 
mitigation would somehow reduce actual levels of acoustic exposure, and 
we disagree that ``each of the inputs is purposely developed to be 
conservative''--indeed, neither the Associations nor BOEM provide any 
support for the latter statement. Although it may be correct that 
conservativeness accumulates throughout the analysis, the Associations 
do not adequately describe the nature of conservativeness associated 
with model inputs or to what degree (either quantitatively or 
qualitatively) such conservativeness ``accumulates.''
    Comment: One individual stated that NMFS should consider how 
``animal behavioral response can condition exposure,'' noting that 
behavioral responses may result in effects to the potential amount and 
intensity of take. We believe the commenter is suggesting that the way 
any specific animal moves through the water column in initial response 
to the sound can change the manner in which they are subsequently 
further exposed to the sound.
    Response: The commenter seemingly indicated that some species 
should be expected to dive downwards rather than exhibit lateral 
avoidance. While we agree that this may occur, we do not agree that 
this would result in an increase in intensity of take--and such an 
occurrence could not by definition result in an increase in the 
absolute amount of take, as the animal in question would already be 
considered ``taken.'' Given relative motion of the vessel and the 
animal, there is no evidence to support that avoidance of the noise 
through downward, rather than lateral, movement would result in a 
meaningful increase in the duration of exposure, as implied by the 
commenter.
    Comment: The Associations stated that it is unclear whether the 
take estimates include repeated exposures and that, if so, the 
estimates do not identify the number of repeated exposures, instead 
presenting a total number of estimated exposures by species. The 
Associations state that NMFS must perform additional analysis to 
identify the actual number of individual marine mammals that may be 
incidentally taken.
    Response: The take estimates presented in our Notice of Proposed 
IHAs, and those shown in Table 6 of this notice, represent total 
estimated instances of exposure. We agree with the Associations that an 
understanding of the numbers of individuals affected by the total 
estimated instances of exposure is relevant, both for the small numbers 
analysis (a small numbers analysis is appropriately made on the basis 
of individuals taken rather than total takes, when such information is 
available) but also for assessing potential population-level impacts in 
a negligible impact analysis. We also agree that this information is 
relevant to these analyses and important to use, when available. In 
fact, one applicant (TGS) provided an analysis of individuals exposed; 
following review of public comments and re-evaluation of TGS's 
application, we considered this information in our small numbers 
analysis for TGS. However, without such information, an assumption that 
the total estimated takes represent takes of different individuals is 
acceptable in that it represents a conservative estimate of the total 
number of individuals taken made in the absence of sufficient 
information to differentiate between individuals exposed and instances 
of exposure, and is also generally a reasonable approach given the 
large, dispersed spatial scales over which the surveys operate. The 
MMPA does not require that NMFS undertake any such analysis and, in 
fact, sufficient information is not typically available to support such 
an analysis.
    Comment: NRDC states that masking results in take of marine 
mammals, and that NMFS must account for this in its take estimates.
    Response: We addressed our consideration of masking in greater 
detail in a previous response. We acknowledge that masking may impact 
marine mammals, particularly baleen whales, and particularly when 
considered in the context of the full suite of regulated and 
unregulated anthropogenic sound contributions overlaying an animal's 
acoustic habitat. However, we do not agree that masking effects from 
the incremental noise contributions of individual activities or sound 
sources necessarily, or typically,

[[Page 63293]]

rise to the level of a take. While it is possible that masking from a 
particular activity may be so intense as to result in take, we have no 
information suggesting that masking of such intensity and duration 
would occur as a result of the specified activities. As described in 
our previous comment response, potential effects of a specified 
activity must be accounted for in a negligible impact analysis, but not 
all responses or effects result in take nor are those that do always 
readily quantified. In this case, while masking is considered in the 
analysis, we do not believe it will rise to the level of take in the 
vast majority of exposures. However, specifically in the case of these 
five surveys, in the unanticipated event that any small number of 
masking incidents did rise to the level of a take, we would expect them 
to be accounted for in the quantified exposures above 160 dB. Given the 
short duration of expected noise exposures, any take by masking in the 
case of these surveys would be most likely to be incurred by 
individuals either exposed briefly to notably higher levels or those 
that are generally in the wider vicinity of the source for 
comparatively longer times. Both of these situations would be captured 
in the enumeration of takes by Level B harassment, which is based on 
exposure at or above 160 dB, which also means the individual 
necessarily spent a comparatively longer time in the adjacent area 
ensonified below 160 dB, but in which masking might occur if the 
exposure was notably longer.
    Comment: NRDC, the MMC, and others state that NMFS's Level A 
harassment exposure analysis contains potentially significant errors. 
The MMC recommends that NMFS (1) provide company-specific Level A 
harassment zones for each functional hearing group, and (2) re-estimate 
the numbers of Level A harassment. NRDC states that, by relying on 
BOEM's 2014 PEIS, NMFS did not use the best available science, e.g., 
use of earlier density data (DoN, 2007) rather than Roberts et al. 
(2016). NRDC goes on to cite as an additional flaw of the analysis that 
``NMFS assumes that auditory take estimates for high-frequency 
cetaceans depend on the exposure of those species to single seismic 
shots . . . even though the weighted auditory injury zone for high-
frequency cetaceans extends as far as 1.5 kilometers [ . . . . ] The 
size of the injury zone suggests that NMFS' assumption about high-
frequency cetaceans is incorrect, and that the agency should calculate 
auditory injury by applying both the peak-pressure threshold and a 
metric that accounts for exposure to multiple shots (e.g., the 
cumulative sound energy thresholds included in NMFS' guidance).''
    Response: As described in ``Estimated Take,'' NMFS revised the 
approach to assessing potential for auditory injury, and associated 
authorization of take by Level A harassment. NMFS disagrees that the 
prior approach for the proposed IHAs contained ``significant errors.'' 
As stated in our Notice of Proposed IHAs, we used the information 
available to us and made reasonable corrections to account for 
applicant-specific information. However, following review of public 
comments, we determined it appropriate to re-evaluate the analysis and 
subsequently revised our approach as described in ``Estimated Take.'' 
This revised approach is simplified in its use of the available 
information while providing a reasonable assessment of the likely 
potential for auditory injury, and has the advantage of not relying on 
the BOEM PEIS results. While the PEIS results remain a reasonable 
assessment of potential effects from a programmatic perspective, and 
were based on the best available cetacean density information at the 
time the analyses were conducted, they do not use the best cetacean 
density information currently available (Roberts et al., 2016), and 
also did not recognize that the potential for Level A harassment 
occurrence for mid-frequency cetaceans is discountable (described in 
detail in ``Estimated Take''). However, the second portion of NRDC's 
comment is incorrect: The peak pressure injury zones referred to by 
NRDC as extending as far as 1.5 km are not weighted for hearing 
sensitivity, as it is inappropriate to do so for exposure to peak 
pressure received levels (NMFS, 2018). Applicant-specific zones are 
shown in Table 5; all zones based on accumulation of energy are very 
small for high-frequency cetaceans. It is unclear what NRDC's 
recommendation to ``calculate auditory injury by applying both the 
peak-pressure threshold and a metric that accounts for exposure to 
multiple shots'' means, as the former is predominant for high-frequency 
cetaceans, while zones based on the latter are essentially non-
existent. As recommended by the MMC, we have provided company-specific 
Level A harassment zones for each functional hearing group (see Table 
5).
    Comment: One individual asserted that NMFS fails to account for 
variability in group size and distribution of various species, stating 
that while the best estimate of take may be a fraction of an individual 
in practice either no individuals will be taken, or one or more groups 
will be taken. The individual suggested that NMFS should decide whether 
it may authorize one or more large groups, rather than estimates of a 
fraction of an individual.
    Response: We agree with this comment. Accordingly, and as described 
in our Notice of Proposed IHAs, we did not propose to authorize take 
less than the average group size for any species. In fact, our take 
authorization for a group of species deemed ``rare'' was based entirely 
on an assumption of one encounter with a group, i.e., we authorize take 
equating to one average group size.
    Comment: NRDC asserts that NMFS fails to account for forms of 
injury that are reasonably anticipated, stating that permanent hearing 
loss (i.e., Level A harassment) may occur through mechanisms other than 
PTS, and that behaviorally-mediated injury may occur as a result of 
exposure to airgun noise. NRDC states that NMFS must account for these 
mechanisms in its assessment of potential injury.
    Response: NMFS is aware of the work by Kujawa and Liberman (2009), 
which is cited by NRDC. The authors report that in mice, despite 
completely reversible threshold shifts that leave cochlear sensory 
cells intact, there were synaptic level changes and delayed cochlear 
nerve degeneration. However, the large threshold shifts measured (i.e., 
maximum 40 dB) that led to the synaptic changes shown in this study are 
within the range of the large shifts used by Southall et al. (2007) and 
in NMFS's technical guidance to define PTS onset (i.e., 40 dB). It is 
unknown whether smaller levels of temporary threshold shift (TTS) would 
lead to similar changes or what may be the long-term implications of 
irreversible neural degeneration. The effects of sound exposure on the 
nervous system are complex, and this will be re-examined as more data 
become available. It is important to note that NMFS's technical 
guidance incorporated various conservative factors, such as a 6-dB 
threshold shift to represent TTS onset (i.e., minimum amount of 
threshold shift that can be differentiated in most experimental 
conditions); the incorporation of exposures only with measured levels 
of TTS (i.e., did not incorporate exposures where TTS did not occur); 
and assumed no potential of recovery between intermittent exposures. 
NMFS disagrees that consideration of likely PTS is not sufficient to 
account for reasonably expected incidents of auditory injury.
    There is no conclusive evidence that exposure to airgun noise 
results in behaviorally-mediated forms of injury. Behaviorally-mediated 
injury (i.e., mass stranding events) has been primarily

[[Page 63294]]

associated with beaked whales exposed to mid-frequency naval sonar. 
Tactical sonar and the alerting stimulus used in Nowacek et al. (2004) 
are very different from the noise produced by airguns. One should 
therefore not expect the same reaction to airgun noise as to these 
other sources.
    Comment: TGS recommends that NMFS (1) recalculate take estimates to 
account for mitigation; (2) remove take estimates associated with the 
disallowed use of a mitigation gun; and (3) ensure that we do not 
double-count takes when considering takes by both Level A and Level B 
harassment.
    Response: We agree with these recommendations and have done as 
requested; please see ``Estimated Take'' for further detail. We do note 
that, with regard to accounting for mitigation in calculating take 
estimates, our analysis involved only an accounting of take avoided for 
certain species as a result of the implementation of time-area 
restrictions. We did not attempt to account for the potential efficacy 
of other mitigation requirements in avoiding take.
    Comment: The Florida Department of Environmental Protection (FLDEP) 
wrote that NMFS needs to be cautious in relying on the efficacy of 
mitigation measures to estimate take by Level A harassment, 
particularly with regard to North Atlantic right whales. They noted 
additional information on the effectiveness of proposed mitigation is 
necessary.
    Response: While we agree with the commenters that caution is 
warranted in assuming that standard mitigation measures, such as 
shutdowns, will be effective in avoiding Level A harassment, we note 
that our estimation of likely take by Level A harassment does not 
substantively rely on such assumptions. As described in ``Estimated 
Take,'' auditory injury of mid-frequency cetaceans is highly unlikely, 
for reasons unrelated to mitigation. In estimating likely Level A 
harassment of high-frequency cetaceans, we did not consider mitigation 
at all, as the instantaneous exposures expected to result in auditory 
injury are amenable to a straightforward quantitative estimate. 
However, our Level A harassment take estimates for low-frequency 
cetaceans are based on a more qualitative analysis that does consider 
the implementation of mitigation, as is appropriate. We do not assume 
in any case that real-time mitigation would be totally effective in 
avoiding such instances, but for the theoretical injury zone sizes 
considered here for low-frequency cetaceans, which are based on the 
accumulation of energy, it is reasonable to assume that large whales 
may be observed when close to the vessel. Therefore, shutdown may be 
implemented and accumulation of energy halted such that actual 
instances of injury should not be considered likely. Our estimated 
instances of Level A harassment for low-frequency cetaceans consider 
the expected frequency of encounter for different species and the 
expectation that mitigation will be effective in avoiding some 
instances of Level A harassment, but also the likelihood that for some 
species that would be encountered most frequently, some instances of 
Level A harassment are likely unavoidable. Specifically for the right 
whale, we primarily consider that our required time-area restriction 
will avoid most acute exposures of the species (or that comparable 
protection will be achieved through implementation of a NMFS-approved 
mitigation and monitoring plan at distances between 47-80 km offshore) 
(as shown in the very low numbers of estimated take by Level B 
harassment, which account for the time-area restriction). Given such a 
low assumed encounter rate, the likelihood of Level A harassment for 
the species is correctly considered discountable. Please see our 
discussion in ``Estimated Take'' for further detail.
    Comment: NRDC asserts that NMFS has failed to account for the 
effects of stress on marine mammals.
    Response: As NRDC acknowledges, we addressed the available 
literature regarding potential impacts of stress resulting from noise 
exposure in marine mammals. As described in that discussion, stress 
responses are complicated and may or may not have meaningful impacts on 
marine mammals. NRDC implies that NMFS must (1) enumerate takes 
resulting from stress alone and (2) specifically address stress in its 
negligible impact analyses. The effects of stress are not 
straightforward, and there is no information available to inform an 
understanding of whether it is reasonably likely that an animal may 
experience a stress response upon noise exposure that would not be 
accounted for in NMFS's enumeration of takes via exposure to noise 
exceeding 160 dB. NRDC provides no useful information as to how such an 
analysis might be carried out. With regard to NMFS's negligible impact 
analyses, we believe that the potential effects of stress are addressed 
and subsumed within NMFS's considerations of magnitude of effect and 
likely consequences. Similarly, NRDC provides no justification as to 
why stress would appropriately be considered separately in these 
analyses, and no useful recommendation as to how to do so, if 
appropriate. We believe we have appropriately acknowledged the 
potential effects of stress, and that these potential effects are 
accounted for within our overall assessment of potential effects on 
marine mammals.
    Comment: The MMC recommends that NMFS (1) determine whether the 
specific animat density used by Spectrum is appropriate and (2) 
depending on the outcome of that assessment, either authorize 
uncorrected take numbers from Spectrum's application, or re-estimate 
the numbers of Level B harassment takes using a higher animat density.
    Response: We appreciate the MMC's consideration of this issue. 
Following evaluation of the comment, we confirm that the animat density 
used by Spectrum is appropriate. As stated by Marine Acoustics, Inc. 
(MAI)--which has years of experience in the field of acoustic modeling 
and performed the modeling for Spectrum (as well as ION) according to 
state-of-the science best practices--the modeled animat density value 
was determined through a sensitivity analysis that examined the 
stability of the predicted estimate of exposure levels as a function of 
animat density. The modeled density was determined to accurately 
capture the full distributional range of probabilities of exposure for 
the proposed survey, and is therefore appropriate. In describing the 
original modeling, MAI stated that in most cases the animat density 
represented a higher density of animats in the simulation than occurs 
in the real world. This ``over-population'' allowed the calculation of 
smoother distribution tails, and in the final analysis all results were 
normalized back to the actual estimated density for the species or 
group in question. This remains the case when using the revised density 
estimates from Roberts et al. (2016). We disagree with MMC's contention 
that the mitigation assumptions used by Spectrum in modeling Level B 
harassment takes were inappropriate; therefore, we retain the estimates 
proposed for authorization (as modified using the newer Roberts et al. 
(2016) density values).
    Comment: The FLDEP stated that NMFS should account for uncertainty 
in take estimates, including uncertainty about marine mammal density, 
sound propagation models, and auditory thresholds, and that these 
factors should ``all manifest as uncertainty around take estimates and 
be reported in and considered for IHAs.''
    Response: We agree with the commenter that it would be useful to

[[Page 63295]]

understand the degree of confidence in take estimates through some 
measure of uncertainty around the estimate, and that uncertainty can 
accrue through all of the mentioned aspects of the take estimation 
process. However, we believe that the take estimates are reasonable 
best estimates. Measuring uncertainty around a take estimate is not 
something that has been accomplished in the past, and the commenter 
provides no recommendation as to how they believe this should be done.
    Comment: The NAMA stated that an IHA should be revoked if it is 
found that a take by Level A harassment has occurred.
    Response: Level A harassment, which is defined as an act with the 
potential to injure a marine mammal, may be authorized through an IHA, 
as we have done here.
    Comment: The New York State Department of Environmental 
Conservation stated that the amount of takes by Level A harassment 
proposed for humpback whales is considerable when considered in context 
of the ongoing UME, and that NMFS should give more consideration to 
this concern.
    Response: We have considered the ongoing effects of the humpback 
whale UME in our evaluation. We also reiterate that Level A harassment 
refers to injury, and therefore cannot be directly equated to serious 
injury or mortality, and further that the estimated takes by Level A 
harassment likely represent only onset of mild PTS. However, 
separately, we have revised our estimates of Level A harassment for all 
species (see ``Estimated Take''), resulting in much lower estimates for 
humpback whales. The revised results of this analysis should obviate 
the concern expressed here.
    Comment: OCR stated that NMFS should consider the potential use of 
ancillary noise sources (e.g., side-scan or multibeam bottom profiling 
sonars) in estimating take, and notes that these sources have been 
associated with marine mammal strandings.
    Response: We did consider this potential avenue of acoustic 
exposure. We understand that, generally, vessel operators plan to use 
standard navigational echosounders (single beam) operated at relatively 
high frequencies (>18 kHz). In addition, it is possible that some 
applicants may use a low-level acoustic pinger to help position their 
towed gear. It is possible that some marine mammals could detect and 
react to signals from these sources (although this is less likely for 
low-frequency cetaceans, and these species would not likely detect 
signals from these systems if they are operated above 35 kHz). However, 
the vast majority of the time echosounders would be in use, so would 
airguns which have much higher source levels and are expected to result 
in more severe reactions than any associated with echosounders 
specifically. We would expect that in most cases, any response would be 
to airguns rather than the echosounder itself. We recognize that there 
would be limited use of echosounders or pingers while airguns are not 
active, for example, when vessels are in transit from port to areas 
where surveys will occur. However, we do not believe this results in 
meaningful exposure to marine mammals since, given the lower source 
levels and higher frequencies of echosounders and pingers, animals 
would need to be very close to the transducer to receive source levels 
that would produce a behavioral response (Lurton, 2016), much less one 
that would result in a response of a degree considered to be take.
    In extreme circumstances, some echosounders and pingers may also 
have the potential to cause injury, and in one case evidence indicates 
such a system likely played a contributing role in a cetacean stranding 
event. However, injury (or any threshold shift) is even less likely 
than behavioral responses since animals would need to be even closer to 
the transducer for these to occur. It is also important to note that 
the system implicated in the stranding event was a lower-frequency (12-
kHz), higher-power deepwater mapping system; typical navigational 
systems, including those that the applicants here would use, would have 
lower potential to cause similar responses. Kremser et al. (2005) 
concluded the probability of a cetacean swimming through the area of 
exposure when such sources emit a pulse is small, as the animal would 
have to pass at close range and be swimming at speeds similar to the 
vessel in order to receive multiple pulses that might result in 
sufficient exposure to cause TTS. This finding is further supported by 
Boebel et al. (2005), who found that even for echosounders with source 
levels substantially higher than those proposed here, TTS is only 
possible if animals pass immediately under the transducer. Burkhardt et 
al. (2013) estimated that the risk of injury from echosounders was less 
than three percent that of vessel strike, which is considered extremely 
unlikely to occur such that it is discountable. In addition, modeling 
by Lurton (2016) of multibeam echosounders indicates that the risk of 
injury from exposure to such sources is negligible.
    Navigational echosounders are operated routinely by thousands of 
vessels around the world, and to our knowledge, strandings have not 
been correlated with their use. The echosounders and pinger proposed 
for use differ from sonars used during naval operations, which 
generally have higher source levels, lower frequencies, a longer pulse 
duration, and more horizontal orientation than the more downward-
directed echosounders. The sound energy received by any individuals 
exposed to an echosounder during the proposed seismic survey activities 
would be much lower relative to naval sonars, as would be the duration 
of exposure. The area of possible influence for the echosounders is 
also much smaller, consisting of a narrow zone close to and below the 
source vessels as described previously for TTS and PTS. Because of 
these differences, we do not expect the proposed echosounders and 
pinger to contribute to a marine mammal stranding event. In summary, 
any effects that would be considered as take are so unlikely to occur 
as a result of exposure from ancillary acoustic sources as to be 
considered discountable.

Marine Mammal Protection Act--General

    Comment: Several groups indicated a belief that NMFS's proposal to 
issue the five IHAs contradicts Congressional intent behind the MMPA. 
For example, Clean Ocean Action (COA) stated that issuance of the IHAs 
would be incompatible with the original intent of the MMPA. Sea 
Shepherd Legal stated that the legislative history of the MMPA makes 
clear that the precautionary principle must be applied and bias must 
favor marine mammals, and opines that NMFS's proposed issuance of the 
IHAs ``undermines the MMPA's prioritization of conservation.''
    Response: NMFS disagrees that these actions contradict any 
requirement of the MMPA or are contrary to Congressional intent as 
expressed in relevant provisions of the statute. Neither the MMPA nor 
NMFS's implementing regulations include references to, or requirements 
for, the precautionary approach, nor is there a clear, agreed-upon 
description of what the precautionary approach is or would entail in 
the context of the MMPA or any specific activity. Nevertheless, the 
MMPA by nature is inherently protective, including the requirement to 
mitigate to the lowest level practicable (``least'' practicable adverse 
impacts, or ``LPAI,'' on species or stocks and their habitat). This 
requires that NMFS assess measures in light of the LPAI standard. To 
ensure that we fulfill that requirement, NMFS considers all

[[Page 63296]]

potential measures (e.g., from recommendations or review of available 
data) that have the potential to reduce impacts on marine mammal 
species or stocks, their habitat, or subsistence uses of those stocks, 
regardless of whether those measures are characterized as 
``precautionary.''
    Comment: Several groups stated that the duration of the public 
comment period was inadequate. A group of fourteen U.S. Senators urged 
NMFS to extend the comment period to at least 150 days (30 for each 
applicant). They wrote that publishing the notice of proposed IHAs had 
little notice, a short comment period, and no public hearings, adding 
that the notice of proposed IHAs addresses two applications that NMFS 
had not previously made available for public review. Some commenters 
decried what they perceived as a lack of stakeholder outreach. Multiple 
groups requested that NMFS hold public hearings in the affected regions 
about the proposed IHAs and their potential impacts.
    Response: NMFS has satisfied the requirements of the MMPA, which 
requires only that NMFS publish notice of a proposed authorization and 
request public comment for a period of 30 days. In fact, NMFS exceeded 
this requirement by extending the public comment period by 15 days, for 
a total period of 45 days. By publishing a joint notice of the five 
proposed IHAs rather than five separate concurrent notices, NMFS 
provided for more efficient public review and comment on these 
substantially similar actions. Although NMFS acknowledges that these 
are five separate actions, there is no requirement to provide for 
consecutive review periods (i.e., five 30-day periods totaling 150 
days). Although not required, NMFS in 2015 published a notice of 
receipt of applications received to afford opportunity for public 
review and comment. Therefore, NMFS provided an opportunity for review 
of the applications for 30 days followed by a 45-day review of the 
proposed IHAs, for a total of 75 days of review--far above what is 
required by the MMPA. As stated earlier in this document, the 
additional two applications received following the 2015 review were 
substantially similar to those offered for review, and we determined 
that publishing a notice of their receipt would not provide any 
additional useful information.
    Overall, we believe that there has been sufficient opportunity for 
public engagement with regard to the proposed surveys, through 
opportunities associated with NMFS's consideration of the requested 
IHAs under the MMPA and those associated with BOEM's consideration of 
requested permits under OCSLA (or through other associated statutory 
requirements). The public, coastal states, and other stakeholders have 
had substantial opportunity for involvement via processes related to 
the Coastal Zone Management Act (CZMA), NEPA, OCSLA, and the MMPA. In 
2014, BOEM completed their PEIS, with NOAA acting as a cooperating 
agency in development of the PEIS. During EIS scoping, BOEM offered two 
separate comment periods and held seven public meetings in coastal 
states. The draft PEIS was made available for public review and comment 
for 94 days. Public hearings were held in eight coastal states. 
Subsequently, the final PEIS was made available for public comment for 
90 days prior to BOEM's issuance of a Record of Decision. After 
completion of the 2014 PEIS, BOEM made all geophysical survey permit 
requests available for public review and comment for 30 days. With 
NMFS's participation, BOEM subsequently held eight open house meetings 
in coastal states for the public to learn more about the proposed 
surveys and to provide input to the permitting process. In addition, 
NOAA and BOEM engaged with coastal states as required by the CZMA 
federal consistency provision.
    Comment: NRDC states that the specified activities have the 
potential to kill and seriously injure marine mammals, and that NMFS 
cannot therefore authorize the requested incidental take via an IHA. 
NRDC specifically contends that behavioral disturbance (i.e., Level B 
harassment) can result in more severe outcomes (i.e., Level A 
harassment or serious injury or mortality) through secondary effects, 
and that NMFS must consider this. Similarly, Oceana and other 
commenters suggest that Level A harassment (i.e., auditory injury) 
cannot be authorized via an IHA, as it is equivalent to serious injury 
or mortality. In this same vein, commenters relate Level A harassment 
to potential biological removal (PBR) levels, a metric used to evaluate 
the significance of removals from a population (i.e., serious injury or 
mortality).
    Response: We strongly disagree that mortality or serious injury are 
reasonably anticipated outcomes of these specified activities, and the 
commenters do not provide compelling evidence to the contrary. Instead, 
commenters present speculative potentialities, including the contention 
that behavioral disturbance will lead to heightened risk of strike or 
predation. Moreover, the specific example given by NRDC--that the 
migratory path for right whales lies ``in the middle of the'' survey 
area--is plainly incorrect. The migratory path for right whales lies 
along the continental shelf (Schick et al., 2009; Whitt et al., 2013; 
LaBrecque et al., 2015), whereas the survey area extends out to 350 nmi 
from shore, with most survey effort planned for waters where right 
whales do not occur (i.e., waters greater than 1,500 m deep; Roberts et 
al., 2017). More importantly, we require that applicants maintain a 
minimum standoff distance of 90 km from shore from November through 
April (or that comparable protection be achieved through implementation 
of a NMFS-approved mitigation and monitoring plan at distances between 
47-80 km offshore), encompassing the expected migratory path and season 
and obviating any concern regarding potential secondary effects on 
migrating right whales.
    Separately, section 101(a)(5)(D) of the MMPA, which governs the 
issuance of IHAs, indicates that the ``the Secretary shall authorize . 
. . . taking by harassment [ . . . . ]'' The definition of 
``harassment'' in the MMPA clearly includes both Level A and Level B 
harassment.
    Last, PBR is defined in the MMPA (16 U.S.C. 1362(20)) as ``the 
maximum number of animals, not including natural mortalities, that may 
be removed from a marine mammal stock while allowing that stock to 
reach or maintain its optimum sustainable population'' and is a measure 
to be considered when evaluating the effects of mortality or serious 
injury on a marine mammal species or stock. Level A harassment is not 
equivalent to serious injury and does not ``remove'' an individual from 
a stock. Therefore, it is not appropriate to use the PBR metric to 
directly evaluate the effects of Level A harassment on a stock in the 
manner suggested by commenters.
    Comment: ION expressed concern regarding proposed IHA language 
indicating that ``taking of any other species of marine mammal is 
prohibited and may result in the modification, suspension, or 
revocation'' of an IHA, requesting that NMFS remove this language. 
Applicants also expressed concern about not being able to avail 
themselves of the IHAs while they are effective.
    Response: The referenced language is standard text in issued IHAs, 
which acknowledges that, while unlikely and unexpected, species for 
which take is not authorized may be observed and unintentionally taken. 
Absent extenuating circumstances, it is unlikely that such an 
occurrence would result in

[[Page 63297]]

the suspension or revocation of an IHA. Rather, in the event that an 
observation is made of an unusual species for which take is not 
authorized, we would consider whether it is likely that the take 
warrants a modification of the IHA in order to include future take 
authorization for that species, or whether it is more likely that the 
observation would not occur again. NMFS has also included a provision 
for an IHA holder to request suspension of the IHA when operations must 
cease for reasons outside the holder's control, excluding certain 
circumstances, for a limited period.

Least Practicable Adverse Impact

    Comment: NRDC believes NMFS relies on a ``flawed interpretation'' 
of the least practicable adverse impact standard. They state that NMFS 
(1) wrongly imports a population-level focus into the standard, 
contrary to the ``clear'' holding of the Ninth Circuit in NRDC v. 
Pritzker; (2) inappropriately ``balances'' or weighs effectiveness 
against practicability without sufficient analysis, counter to 
Pritzker, using the seasonality of Area #5 and NMFS's core abundance 
approaches as examples; and (3) must evaluate measures on the basis of 
practicability (which connotes feasibility), not practicality (which 
connotes usefulness)--and evaluating on the basis of practicality would 
be arbitrary and capricious.
    Response: We carefully evaluated the Ninth Circuit's opinion in 
Pritzker and believe we have fully addressed the Court's concerns. Our 
discussion of the least practicable adverse impact standard in the 
section entitled ``Mitigation'' explains why we believe a population 
focus is a reasonable interpretation of the standard. With regard to 
the second point, we disagree that the Ninth Circuit's opinion requires 
such a mechanical application of the factors that must be considered in 
assessing mitigation options. Finally, we agree with the commenter that 
we must evaluate measures on the basis of practicability, and for these 
IHAS we have done so. Our assessment of measures for practicability 
looked at appropriate considerations, as demonstrated by our discussion 
in this Notice. This included cost and impact on operations. We note 
that although not directly relevant for these IHAs, in the case of a 
military readiness activity, practicality of implementation is 
explicitly part of the practicability assessment. Thus, the two 
concepts are not entirely distinct.
    Comment: In determining whether proposed IHAs meet the least 
practicable adverse impact (LPAI) standard, the MMC recommends that 
NMFS (1) identify the potential adverse impacts that it has identified 
and is evaluating; (2) specify what measures might be available to 
reduce those impacts; and (3) evaluate whether such measures are 
practicable to implement. The MMC further suggests that NMFS provided 
``virtually no analysis to support'' our conclusions.
    Response: The MMC identifies a specific manner in which it 
recommends NMFS consider applicable factors in its least practicable 
adverse impact analysis, however, NMFS has clearly articulated the 
agency's interpretation of the LPAI standard and our evaluation 
framework in the ``Mitigation'' section of this notice. NMFS disagrees 
that analysis was not provided to support our least practicable adverse 
impact findings. Specifically, NMFS identifies the adverse impacts that 
it is considering in the LPAI analysis, and comprehensively evaluates 
an extensive suite of measures that might be available to reduce those 
impacts (some of which are adopted and some that are not) both in the 
context of their expected ability to reduce impacts to marine mammal 
species or stocks and their habitat, as well as their practicability 
(see ``Mitigation'' and ``Negligible Impact Analyses and 
Determinations'' sections).
    Comment: TGS recommended that NMFS ``model how many shut-down and 
delay actions would be expected for a survey'' in evaluating 
practicability, suggesting that ``animat modeling could be used to 
accomplish this estimate.''
    Response: NMFS is not aware of data sources that would 
appropriately inform such an analysis, and does not agree that such an 
analysis is either practical or necessary. Moreover, we believe we have 
addressed the commenter's concern by removing a number of shutdown 
measures (in response to other public comments) that we determined were 
likely ineffective and/or impracticable or otherwise unwarranted, thus 
minimizing the accumulation of potential for shutdown and delay 
actions. We also note that seismic operators have successfully and 
practicably implemented shutdowns in multiple regions, both in the 
United States and in other countries where seismic mitigation protocols 
have been prescribed, and that larger shutdown zones have previously 
been required of operators in the U.S. Arctic as well as for research 
seismic cruises, without any known practicability issues. We have 
appropriately accounted for issues related to practicability in our 
analysis of the appropriate suite of required mitigation measures.

Negligible Impact

    Comment: As described briefly in a previous comment and response, 
NRDC asserts that NMFS should conduct a combined negligible impact 
analysis for all five specified activities, in consideration of the 
aggregate take across all five surveys in the same geographical region, 
over the same period of time, and with ``substantially similar impacts 
on marine mammals.'' NRDC states that NMFS's failure to do so does not 
meet our legal obligations under the MMPA and is ``contrary to common 
sense and principles of sound science.'' Other commenters offer similar 
comments. NRDC cites to legislative history that indicates ``specified 
activity'' includes all actions for which ``the anticipated effects 
will be substantially similar.'' H.R. Rep. No. 97-228 (Sept. 16, 1981), 
as reprinted in 1981 U.S.C.C.A.N. 1458, 1469. Further, NRDC cites to 
NMFS's 1989 implementing regulations as further evidence that NMFS must 
``evaluate the impacts resulting from all persons conducting the 
specified activity, not just the impacts from one entity's 
activities.'' Based on this, NRDC argues that NMFS must make a finding 
that the authorized activity--which includes all five IHA 
applications--will have a negligible impact on the affected species or 
stocks.
    Response: We considered five distinct specified activities and, 
therefore, performed five distinct negligible impact analyses. As we 
said in a previous response to comment, we believe the ``specified 
activity'' for which incidental take coverage is being sought under 
section 101(a)(5)(D) is appropriately defined and described by the 
applicant. Here there are five specified activities, with a separate 
applicant for each.
    Although NRDC's comment correctly cites the pertinent language from 
section 101(a)(5)(D) (which was enacted in 1994), it refers to 
legislative history from 1981 in support of its argument. But that 
legislative history corresponds to Congress' enactment of the provision 
for incidental take regulations. Because the IHA provisions were added 
in 1994, citations from the 1981 legislative history cannot accurately 
be referenced as statements made ``in enacting this provision.'' More 
substantively, the sentence from which NRDC quotes was, in our view, 
for the purpose of instructing the agencies to avoid promulgating 
incidental take regulations that are overly broad in their scope (``It 
is the intention of the Committee that [ . . . ] the specified activity 
[ . . . ] be narrowly identified so that

[[Page 63298]]

the anticipated effects will be substantially similar.''). Similarly, 
the discussion from NMFS's and the U.S. Fish and Wildlife Service's 
1989 implementing regulations (again, before the 1994 enactment of 
section 101(a)(5)(D)) was in reference to section 101(a)(5)(A), the 
provision for incidental take regulations. There the focus was on 
ensuring that the negligible impact evaluation for an incidental take 
regulation under section 101(a)(5)(A)--not incidental harassment 
authorizations under section 101(a)(5)(D)--included the effects of the 
total taking by all the entities anticipated to be conducting the 
activity covered by the incidental take regulation.
    We do not mean to suggest that the legislative history for section 
101(a)(5)(A) and our implementing regulations that preceded enactment 
of section 101(a)(5)(D) have no application to that section. We 
recognize there is considerable overlap between the two provisions. 
However, there are enough differences that the two provisions should 
not be casually conflated with one another.
    Comment: The Associations state that they concur with NMFS's 
preliminary determinations of negligible impact on the affected species 
or stocks. However, their comments go on to claim that the 
``magnitude'' and ``impact'' ratings that inform our negligible impact 
determinations as part of our negligible impact analysis framework are 
overly conservative, and that they disagree with these aspects of our 
negligible impact analyses.
    Response: We appreciate the Associations' concurrence with our 
overall determinations. However, we disagree with the statements 
regarding aspects of our negligible impact analyses, and feel that 
these statements to some degree reflect a misunderstanding of the 
framework elements. In support of their assertion, the Associations 
claim that ``high'' and ``moderate'' magnitude ratings ``have never 
been observed in the multi-decade history of offshore seismic 
exploration [ . . . . ]'' Magnitude ratings reflect only the amount of 
take that is estimated, as well as the spatial and temporal scale over 
which the take is expected to occur in relation to what is known 
regarding a stock's range and seasonal movements; therefore, it is 
incorrect to reference what has or has not ``been observed'' in 
disputing the validity of the given magnitude ratings. The Associations 
also claim that no survey has had more than an ``insignificant'' impact 
on a marine mammal species or stock, without explaining the meaning 
that they assign to this term in context of their comments or providing 
any evidence (as we have stated, lack of evidence of ``significance'' 
does not constitute evidence of ``insignificance''). As this term bears 
no relevance to the MMPA's ``negligible impact,'' we cannot comment on 
the claim. With regard to the Associations' comment that our assigned 
impact ratings are too high, we again disagree (noting that these 
ratings are developed using the formula described for our negligible 
impact framework); however, absent any constructive recommendations 
relating to the development of the impact ratings or our framework 
overall, we cannot respond further.
    Comment: The MMC recommends that NMFS evaluate the numbers of Level 
A harassment takes, in concert with the Level B harassment takes, using 
the negligible impact analysis framework.
    Response: This comment appears based on a mistaken assumption that 
we ``assessed only the proposed Level B harassment takes'' in our 
negligible impact analyses. It is correct that we did not define 
quantitative metrics relating to amount of potential take by Level A 
harassment. However, as we state in the section entitled ``Negligible 
Impact Analyses and Determinations,'' the authorized taking by Level A 
harassment is so low as to not warrant such detailed analysis. We 
addressed the likely impacts of the minimal amount of takes expected by 
Level A harassment, stating that the expected mild PTS would not likely 
meaningfully impact the affected high-frequency cetaceans, and may have 
minor effects on the ability of affected low-frequency cetaceans to 
hear conspecific calls and/or other environmental cues. For all 
applicants, the expected effects of Level A harassment on all stocks to 
which such take may occur is appropriately considered de minimis.
    Comment: NRDC claims that NMFS underestimates the ``magnitude'' 
component of the negligible impact analyses.
    Response: NRDC suggests that the negligible impact framework used 
in our Notice of Proposed IHAs positions a ``de minimis'' amount of 
take as determinative of an ultimate ``de minimis'' impact rating. 
Although not stated explicitly by NRDC, we agree that this was 
inappropriate and have revised this aspect of our negligible impact 
framework. In effect, the proposed approach meant that a de minimis 
amount of take, which would necessarily lead to a de minimis magnitude 
rating, rendered considerations of likely consequences for affected 
individuals irrelevant. For example, mysticete whales with a de minimis 
amount of take were automatically assigned an overall de minimis impact 
rating, as consequences were considered not applicable in cases where a 
de minimis magnitude rating was assigned. However, the assessed level 
of potential consequences for individual baleen whales of ``medium''--
which is related to inherent vulnerabilities of the taxon and other 
existing population stressors, and is therefore not dependent on the 
specific magnitude rating--would still exist, regardless of the amount 
of take. Under our revised approach, a mysticete whale with a de 
minimis amount of take is assigned a low impact rating, in light of the 
medium consequences rating. These changes are described further in the 
section entitled ``Negligible Impact Analyses and Determinations.''
    NRDC asserts that impacts resulting from each of the five separate 
specified activities on the endangered North Atlantic right whale would 
be greater than negligible, stating that it is ``inconceivable'' that 
impacts should be considered anything less than ``high,'' regardless of 
the expected avoidance of right whales in time and space. We have 
addressed concerns regarding North Atlantic right whales in greater 
detail elsewhere in these comment responses. While we acknowledge that 
there will be some effects to individual right whales, as it is not 
possible to conduct these activities without the potential for impacts 
to whales that venture outside of areas where they are expected to 
occur or that undertake migration at atypical times, impacts to the 
population are in fact effectively minimized for each of these 
specified activities. As described later in this document, we have 
revised our exposure analysis for right whales using the latest and 
best available scientific information, and have appropriately revised 
our prescribed mitigation on the basis of that information, as well as 
public comment, in such a way as to reasonably avoid almost all 
potential right whale occurrence. We also include real-time mitigation 
that would minimize the effect of any disturbance on a right whale, in 
the unexpected event that an individual was encountered in the vicinity 
of a survey. Accordingly, the impact ratings for mysticetes are at 
least ``low'' versus ``de minimis'' (as stated above, we agree that the 
impact rating should likely be greater than de minimis given the 
inherent vulnerabilities of the species).
    NRDC goes on to state that NMFS uses a ``non-conservative'' metric 
in characterizing the amount of take, and

[[Page 63299]]

suggests that we should adopt Wood et al. (2012)'s more conservative 
approach for ESA-listed species. NRDC does not explain how this 
recommendation will better satisfy the statutory requirements of the 
MMPA. As stated by Wood et al. (2012), development of metrics for 
assessment of the magnitude of effect is considered particularly 
subjective. Rather than invent new metrics in the absence of any 
specific rationale or guidance, we retain use of those given by Wood et 
al., which are produced through expert judgment. We disagree that the 
more conservative approach applied by Wood et al. (2012) for ESA-listed 
species is appropriate. We believe that the assessment of amount of 
take is a generic consideration, i.e., that the metrics used to assess 
this factor are appropriately applied similarly to all species. 
Contextual factors, such as the status of the species, are applied 
elsewhere in the analysis, e.g., through consideration of likely 
consequences to individuals or as a second-order function of the 
mitigation that is developed in reflection of specific concerns about a 
given species. NRDC's implication that we did not take account of 
vulnerable populations in our negligible impact framework is incorrect.
    Comment: NRDC asserts that the evaluation of likely consequences to 
individuals from species other than mysticete whales in our negligible 
impact analyses is ``problematic.''
    Response: Overall, NRDC basically provides a blanket suggestion 
that for all species impacts should be considered to be higher than we 
have determined after careful consideration of the available science. 
NRDC also repeatedly claims that we have provided no rational basis for 
our findings. While we acknowledge that we bear the responsibility to 
support our statutory findings, we believe we have satisfied that 
requirement and, further, NRDC does not provide adequate justification 
or evidence to support their claims.
    For sperm whales, NRDC demands that the likely consequences to 
individuals be considered ``high'' rather than ``medium,'' as we have 
done (on the basis of presumed heightened potential for disruption of 
foraging activity). In so doing, NRDC primarily relies upon Miller et 
al. (2009), as has NMFS in assuming some heightened potential for 
foraging disruption. However, the evidence provided by the available 
literature is not nearly as clear as NRDC's comment implies. We agree 
that the work of Miller et al. (2009) indicates that sperm whales in 
the Gulf of Mexico are susceptible to disruption of foraging behavior 
upon exposure to relatively moderate sound levels at distances greater 
than the required general exclusion zone. However, NRDC misstates the 
results of the study in claiming that a nearly 20 percent loss in 
foraging success was documented. Rather, the authors report that buzz 
rates (a proxy for attempts to capture prey) were approximately 20 
percent lower, meaning that the appropriate interpretation would be 
that foraging activity (versus foraging success) was reduced by 20 
percent (Jochens et al., 2008). This is an important distinction, as 
the former implies a cessation of activity--which may include increased 
resting bouts at the surface--during the relatively brief period that 
the surveys transit through the whale's foraging area, whereas the 
latter implies that the whale is continuing to expend energy in the 
hunt for food, without reward. Moreover, while we do believe that these 
results support our contention that exposure to survey noise can impact 
foraging activity, other commenters have interpreted them differently, 
e.g., by focusing on the finding that exposed whales did not change 
behavioral state during exposure or show horizontal avoidance (a 
finding replicated in other studies, e.g., Madsen et al., 2002; Winsor 
et al., 2017), or that the finding of reduced buzz rates was not a 
statistically significant result. In referencing Bowles et al. (1994), 
NRDC fails to state that the observed cessation of vocalization was 
likely in response to a low-frequency tone (dissimilar to airgun 
signals), though a distant airgun survey was noted as producing signals 
that were detectable above existing background noise. However, most 
importantly, we expect that the context of these transitory 2D 
surveys--as compared with 3D surveys that may occur for a longer 
duration in a given location, or with repeated survey activity as may 
occur in an area such as the Gulf of Mexico--means that the potential 
impacts of the possible reduction in foraging activity (i.e., likely 
consequences on individuals) is limited. More recently, Farmer et al. 
(2018) developed a stochastic life-stage structured bioenergetic model 
to evaluate the consequences of reduced foraging efficiency in sperm 
whales, finding that the ultimate effects on reproductive success and 
individual fitness are largely dependent on the duration and frequency 
of disturbance--which are expected to be limited in relation to these 
specified activities. Thus, we believe our conclusion of ``medium'' 
likely consequences is appropriate.
    With regard to Kogia spp., NRDC again suggests that NMFS must 
increase the level of assumed severity for likely consequences to 
individuals. While we agree that the literature with regard to kogiid 
life history is sparse, what literature is available (as cited in our 
Notice of Proposed IHAs) indicates that these species should be 
considered as having a reasonable compensatory ability when provoked to 
temporary avoidance of areas in the vicinity of active surveys. None of 
NRDC's statements on this topic support their contention that these 
consequences should be considered as more severe, i.e., the notion that 
there is little information available regarding stock structure is not 
related to the likely consequences to individuals of disturbance. NRDC 
assumes that such temporary avoidance necessarily results in 
``displacement from optimal to suboptimal habitat'' without any 
support. Moreover, it appears that NRDC misapprehends the conceptual 
underpinnings of our negligible impact analytical framework. The 
expected degree of disturbance (``take'') is determined in the 
``Estimated Take'' section, and then is coupled with an understanding 
of the spatial and temporal scale of such disturbance relative to the 
stock range. Only then is this comprehensive magnitude rating combined 
with the expectation of the likely consequences of the given magnitude 
of effect to yield an overall impact rating that is then considered 
with other relevant contextual factors, such as mitigation and stock 
status, in informing the negligible impact determination (Figure 5). By 
seemingly conditioning its premise on the acoustically sensitive nature 
of kogiids, which is incorporated into the take estimates and accounted 
for in the mitigation requirements, NRDC would have us overly weight 
this aspect of their life history. Our assigned consequences for Kogia 
spp. is appropriate and based on the limited available literature.
    Similarly, for delphinids (for which NRDC also urges a more severe 
assumption of likely consequence to individuals of the given 
disturbance), NRDC states that the consequences must be considered 
higher when the magnitude is high. Again, this is a misapprehension of 
the framework: The assigned ``consequences'' factor is independent of 
the magnitude rating, and is designed to account for aspects of a 
species life history that may make individuals from that species more 
or less susceptible to a biologically significant degree of impact from 
a

[[Page 63300]]

given level of disturbance. NRDC's additional statements regarding 
delphinids appear to again cherry-pick available literature in support 
of its preferred position, e.g., NRDC cites reactions of dolphins to 
Navy training involving explosive detonations (a dissimilar activity) 
and suggests that spotted dolphins are susceptible to greater 
disturbance on the basis of Weir (2008), claiming that this paper 
indicates ``pronounced response of spotted dolphins to operating 
airguns'' and supposedly heightened sensitivity. We do agree that the 
available observational data (e.g., Barkaszi et al., 2012; Stone, 
2015a) show that, in contrast to common anecdotal statements suggesting 
that dolphins do not react at all to airgun noise, dolphins overall 
show increased distances to the noise source or even avoidance when 
airguns are operating. However, as stated elsewhere, these reactions 
may not even be appropriately considered as take (e.g., Ellison et al., 
2012), much less take to which some meaningful biological significance 
should be assigned. In fact, Weir (2008) concludes that, while spotted 
dolphin encounters occurred at a significantly greater distance from 
the airgun array when the guns were firing, there was no evidence of 
displacement from the study area, indicating that even for this 
supposedly more sensitive species, greater likely consequences would 
not be expected. As indicated by Weir (2008), these responses may be 
short-term and also occur over relatively short ranges from the source.
    NRDC concludes its criticism of this aspect of our negligible 
impact analyses by demanding that we weight this assessment of likely 
consequences to individuals more highly in the determination of the 
overall impact rating. However, this appears to again evidence a 
misapprehension of our framework and its function. We certainly agree 
that an activity that is found to take small numbers of marine mammals 
may not be found to satisfy the negligible impact standard. However, 
here, as in their criticism of NMFS's approach to the small numbers 
analysis, NRDC inappropriately conflates the two findings. Here, NRDC 
seems to confuse a low magnitude of effect with the independent small 
numbers finding, rather than understand this magnitude factor as an 
important input to the development of the impact rating. As described 
in greater detail in our section entitled ``Negligible Impact Analyses 
and Determinations,'' the impact rating represents the coupling of the 
magnitude rating and the likely consequences to individuals in order to 
represent the potential impact to the stock (before considering other 
contextual factors). Therefore, although the likely consequences to 
individuals of incidental take may be high, if the magnitude of effect 
is low, then the impact to the stock will not likely be high. NRDC's 
example indicates that it prefers that the likely consequences to 
individuals be determinative of the impact rating, i.e., they state 
that it is inappropriate for a low magnitude rating and high 
consequences rating to couple to produce a moderate impact rating. Our 
development of these rating matrices (Tables 8 and 9) are based on 
expert review (Wood et al., 2012) and appropriately account for the 
factors illustrated in Figure 5.
    Comment: NRDC claims that the negligible impact analyses are 
inappropriately reliant upon the prescribed mitigation and, further, 
that the mitigation will be ineffective.
    Response: First, NMFS did not rely solely on the mitigation in 
order to reach its findings under the negligible impact standard. As is 
stated in our specific analyses, consideration of the implementation of 
prescribed mitigation is one factor in the analyses, but is not 
determinative in any case. In certain circumstances, mitigation is more 
important in reaching the negligible impact determination, e.g., when 
mitigation helps to alleviate the likely significance of taking by 
avoiding or reducing impacts in important areas. Second, while NRDC 
dismisses the importance of our prescribed mitigation by stating that 
it is ``unsupported by evidence,'' NRDC offers no support for their 
conclusions.
    For example, with regard to the North Atlantic right whale, 
consideration of the mitigation in our negligible impact analyses was 
appropriate. That is, it was appropriate to weigh heavily in our 
analyses mitigation that would avoid most exposures of right whales to 
noise at levels that would result in take. We acknowledge that our 
proposed mitigation for right whales was not sufficient. As described 
in greater detail in previous comment responses, as well as in the 
section entitled ``Mitigation,'' we re-evaluated our proposed 
mitigation in light of the public comments we received and on the basis 
of the best available information.
    NRDC elsewhere stresses the importance of developing appropriate 
habitat-based mitigation--that is, avoiding impacts in areas of 
importance for marine mammals--and not relying solely on ``real-time'' 
mitigation (e.g., shutdowns) that allows impacts in those areas but 
minimizes the duration and intensity of those impacts. Yet despite our 
development of time-area measures for those species where the available 
information supports it, NRDC discounts the benefit of avoiding 
disturbance of sensitive and/or deep-diving species in areas where they 
are expected to be resident in greatest numbers. Claims that our 
prescribed time-area restrictions are ineffective and 
``unsubstantiated''--and therefore apparently should not be considered 
in our negligible impact analyses--are contradicted by NRDC's 
statements that habitat-based mitigation are necessary (``Time and 
place restrictions designed to protect important habitat can be one of 
the most effective available means to reduce the potential impacts of 
noise and disturbance on marine mammals.'' (Citing p. 61 of NRDC's 
letter)). However, our revised time-area restriction for right whales 
(or requirement that comparable protection is achieved through 
implementation of a NMFS-approved mitigation and monitoring plan at 
distances between 47-80 km offshore) may have alleviated some of the 
concerns expressed in the comment.
    NRDC also misunderstands the degree to which we rely on shutdowns 
for sensitive or vulnerable species, including right whales and beaked 
whales, at extended distances. We agree that these measures in and of 
themselves are not likely to carry substantial benefit, especially for 
cryptic species such as beaked whales that are unlikely to be observed. 
The prescribed habitat-based mitigation, i.e., time-area restrictions, 
is obviously more important in minimizing impacts to these species. 
However, having determined practicability, we also believe that it 
makes sense to minimize the duration and intensity of disturbance for 
these species when they are observed, and so include them in the suite 
of prescribed measures and discuss them where appropriate. Despite 
their dismissal of these requirements, we presume NRDC agrees that the 
duration and intensity of disturbance of sensitive species should be 
minimized where practicable.
    In summary, we have prescribed practicable mitigation that largely 
eliminates takes of North Atlantic right whales, as indicated by the 
best available science and further minimizes impacts by mitigating for 
duration and intensity of exposures. Separately, we have developed 
mitigation that protects use of some of the most important habitat in 
the region for other sensitive species. We consider these measures 
appropriately as mitigating factors in the

[[Page 63301]]

context part of our negligible impact analyses.
    Comment: Oceana asserts that our findings of negligible impact are 
improper. In so doing, they make points that are substantively 
responded to elsewhere in these comment responses. In addition, they 
also make repeated reference to the PBR value, claiming that where 
harassment takes exceed the PBR value for a stock, NMFS must deny the 
IHA request for failure to meet the negligible impact standard.
    Response: We reiterate that the PBR metric concerns levels of 
allowable removals from a population, and is not directly related to an 
assessment of negligible impact for these specified activities, which 
do not involve any expected potential for serious injury or mortality. 
As noted previously, PBR is not an appropriate metric with which to 
evaluate Level B harassment and NMFS has described and used an 
analytical framework that is appropriate. We appropriately do consider 
levels of ongoing anthropogenic mortality from other sources, such as 
commercial fisheries, in relation to calculated PBR values as an 
important contextual factor in our negligible impact analysis 
framework, but a direct comparison of takes by harassment to the PBR 
value is not germane. While it is conceptually possible to link 
disturbance to potential fitness impacts to individuals over time 
(e.g., population consequences of disturbance), we have no evidence 
that is the case here.

Small Numbers

    Comment: The MMC and multiple commenters recommend that NMFS 
provide additional explanation to support its selection of the 30-
percent limit on marine mammal taking as meeting the small numbers 
determination for the proposed authorizations. NRDC states that the 
interpretation of ``small numbers'' presented by NMFS in our Notice of 
Proposed IHAs is contrary to the plain meaning and purpose of the MMPA, 
in part because NMFS did not provide a reasoned basis for the take 
limit proposed (i.e., 30 percent) (MMC and others similarly recommended 
that NMFS provide additional explanation to support its selection of 
the 30-percent limit on marine mammal taking as meeting the small 
numbers determination for the proposed authorizations). NRDC makes four 
specific claims. First, NRDC states that 30 percent cannot be 
considered a ``small number.'' Second, NRDC states that Congress 
intended that takes be limited to ``infrequent, unavoidable'' 
occurrences, and that NMFS has not explained why the taking would 
infrequent or unavoidable. Third, NRDC contends that NMFS should define 
different small numbers thresholds on the basis of conservation status 
of individual species. Finally, NRDC believes that NMFS must account 
for ``additive and adverse synergistic effects'' that may occur due to 
multiple concurrent surveys in conducting a small numbers analysis.
    Response: NMFS agrees that the Notice of Proposed IHAs did not 
provide adequate reasoning for the 30 percent limit. Please see the 
``Small Numbers Analyses'' section of this Notice. However, we disagree 
with NRDC's arguments on this topic. Although NMFS has struggled to 
interpret the term ``small numbers'' given the limited legislative 
history and the lack of a biological underpinning for the concept, we 
have clarified and better described our approach to small numbers. As 
discussed in the section entitled ``Small Numbers Analyses,'' we 
describe that the concept of ``small numbers'' necessarily implies that 
there would also be quantities of individuals taken that would 
correspond with ``medium'' and ``large'' numbers. As such, we have 
established that one-third of the most appropriate population abundance 
number--as compared with the assumed number of individuals taken--is an 
appropriate limit with regard to ``small numbers.'' This relative 
approach is consistent with Congress's statement that ``[small numbers] 
is not capable of being expressed in absolute numerical limits'' (H.R. 
Rep. No. 97-228).
    NRDC claims that a number may be considered small only if it is 
``little or close to zero'' or ``limited in degree.'' While we do not 
accept that a dictionary definition of the word ``small'' is an 
acceptable guide for establishment of a reasoned small numbers limit, 
we also note that NRDC cherry-picks the accepted definitions in support 
of its favored position. The word ``small'' is also defined by Merriam-
Webster Dictionary as ``having comparatively little size,'' which 
comports with the small numbers interpretation developed by NMFS and 
offered here. See www.merriam-webster.com/dictionary/small. NRDC 
cherry-picks the relevant language by claiming that Congress intended 
that the agency limit takes to those that are ``infrequent, 
unavoidable'' occurrences. The actual Congressional statement is that 
taking of marine mammals should be ``infrequent, unavoidable, or 
accidental.'' This language implies that allowable taking may in fact 
be frequent if it is unavoidable or accidental, both of which are the 
case, even though, in the case of a large-scale, sound-producing 
activity in areas where marine mammals are present, the takes are not 
``infrequent.''
    The argument to establish a small numbers threshold on the basis of 
stock-specific context is unnecessarily duplicative of the required 
negligible impact finding, in which relevant biological and contextual 
factors are considered in conjunction with the amount of take.
    Similarly, NRDC's assertion that take from multiple specified 
activities should be considered in additive fashion when making a small 
numbers finding is not required by section 101(a)(5)(D) of the MMPA. We 
are unclear whether the logic presented in this comment suggests only 
that a single small numbers analysis should be undertaken for the five 
separate specified activities considered herein, or whether NRDC 
believes that all ``taking'' to which a given stock may be subject from 
all ongoing anthropogenic activities should be considered in making a 
small numbers finding for a given specified activity. Regardless, these 
suggestions from NRDC are not founded in any relevant requirement of 
statute or regulation, discussed in relevant legislative history, or 
supported by relevant case law.
    Comment: The MMC recommends that, in developing generally 
applicable guidance for using a proportional standard to make small 
numbers determinations, NMFS either use a sliding scale that accounts 
for the abundance of the species or stock or explain why it believes 
that a single standard should be applied in all cases. The MMC offers 
two examples, on either end of a spectrum, in illustrating its point. 
First, MMC provides the example of a small population of marine 
mammals, stating that ``taking the entire population may arguably 
constitute a small number.'' Second, the MMC provides the example of a 
large population of marine mammals, stating that ``certain types of 
taking from large populations . . . push the limit of what reasonably 
may be considered a small number.''
    Response: NMFS disagrees that such a ``sliding scale'' is necessary 
or appropriate. Under the ``one-third'' interpretation offered here, 
and on which we base our small numbers analyses, take equating to 
greater than one-third of the assumed individuals in the population 
would not be considered small numbers, other than in certain 
extenuating circumstances, such as the brief exposure of a single group 
of marine mammals (as is authorized

[[Page 63302]]

herein for each applicant for such species as the killer whale). In 
both of the MMC's examples, the MMC evidently reverts to an absolute 
magnitude of the number on the ends of the spectrum, without regard for 
the amount of individuals taken relative to the size of the population. 
Historically, such an approach may have served as a meaningful limit on 
actual removals from a population, prior to the development of the PBR 
metric, but is not a useful consideration when evaluating takes by 
Level B harassment from sound exposure. There is no meaningful way to 
define what should be considered as a ``small'' number on the basis of 
absolute magnitude, and the MMC offers no such interpretation or 
justification.
    Comment: The Associations provide a discussion of several topics 
relating to ``small numbers'' and recommend that NMFS's small numbers 
findings be thoroughly explained in the record for these actions.
    Response: We agree that the basis for each finding should be 
explained. Please see our revised explanation in ``Small Numbers 
Analyses.''
    Comment: Oceana claims that NMFS is in violation of the MMPA's 
``small numbers'' requirement for a variety of reasons, including that 
we authorize takes of the ``critically endangered'' North Atlantic 
right whale and because we authorize takes of species for which there 
are no available abundance estimates, and relates the potential 
biological removal metric to the small numbers finding. Oceana and many 
other commenters also make reference to a supposed ``Federal court 
defined'' take limit of 12 percent of the appropriate stock abundance.
    Response: The reference to a ``Federal court defined'' take limit 
of 12 percent for small numbers likely comes from a 2003 district court 
opinion (Natural Resources Defense Council v. Evans, 279 F.Supp.2d 1129 
(N.D. Cal. 2003)). However, given the particular administrative record 
and circumstances in that case, including the fact that our small 
numbers finding for the challenged incidental take rule was based on an 
invalid regulatory definition of small numbers, we view the district 
court's opinion regarding 12 percent as dicta. Moreover, since that 
time the Ninth Circuit Court of Appeals has upheld a small numbers 
finding that was not based on a quantitative calculation. Center for 
Biological Diversity v. Salazar, 695 F.3d 893 (9th Cir. 1012). Second, 
while we agree that there are stocks for which no abundance estimate is 
presented in NMFS's SARs, there are other available abundance estimates 
for all impacted stocks. However, more importantly, there is no 
requirement in the MMPA to authorize take only for stocks with 
available abundance estimates, or even that a small numbers finding 
must necessarily be based on a quantitative comparison to stock 
abundance. We are required only to use the best available scientific 
information in making a small numbers finding; this information may be 
quantitative or qualitative, and may relate to relevant stock 
information other than its overall abundance. Finally, the PBR metric 
defines a level of removals from a population (i.e., mortality) that 
would allow that population to remain at its optimum sustainable 
population level or, if depleted, would not increase the population's 
time to recovery by more than 10 percent. We reiterate that it is 
inappropriate to make comparisons between takes by harassment and the 
PBR value for any stock.
    Comment: The MMC recommends that NMFS include both the numbers of 
Level A and B harassment takes in its analysis of small numbers.
    Response: We agree that this is appropriate and have done so. 
Please see ``Small Numbers Analyses,'' later in this document, for full 
detail.
    Comment: TGS states that NMFS should better explain what it views 
as the most appropriate abundance estimate for each stock.
    Response: Please see our revised discussion of this topic in the 
section entitled, ``Description of Marine Mammals in the Area of the 
Specified Activities.''
    Comment: Several commenters described problems with NMFS's proposed 
approach to ensuring that actual take estimates remained below the 
small numbers threshold proposed in our Notice of Proposed IHAs, i.e., 
a requirement for monthly interim reporting and a proposed process by 
which companies would correct observations of marine mammals to obtain 
an estimate of total takes.
    Response: We agree with many of the points raised by commenters. 
However, we discuss only the fundamental underlying issue here, i.e., 
our proposed small numbers analyses, which did not fully utilize all 
the information that was available to refine the number of individuals 
taken and prompted development of a proposed reporting scheme that was 
roundly criticized. The small numbers analyses, described in our Notice 
of Proposed IHAs, resulted in erroneous assessments that enumerated 
take estimates for some applicants and some species would exceed the 
proposed small numbers threshold. In order to ensure that the proposed 
threshold would not be exceeded, we proposed that applicants would 
submit monthly interim reports, including estimates of actual numbers 
of takes (proposed to be produced via correction of numbers of observed 
animals for certain biases using factors described in Carr et al. 
(2011)), such that an authorization could be revoked if actual take 
exceeded the proposed small numbers threshold. While we believe it is 
appropriate to correct such observations in order to best understand 
the actual number of takes (discussed elsewhere in these comment 
responses), we agree that this proposal was inappropriate, i.e., that 
NMFS should not issue an incidental take authorization for an activity 
for which a small numbers threshold is expected to be exceeded. 
Additionally, such an approach results in a clearly impracticable 
situation for applicants, who commit substantial expenditure towards 
conducting a given survey plan, but who then may be allowed to complete 
only a portion of the plan.
    In summary, as a result of our review of public comments, we re-
evaluated the relevant available information and produced revised small 
numbers analyses (see ``Small Numbers Analyses,'' later in this 
document). The revised small numbers analyses alleviated the need for 
the proposed take reporting scheme and cap, which were also challenged 
by multiple applicant and public commenters.

Mitigation, Monitoring, and Reporting

    Comment: NRDC states that year-round closure is required in the 
area off Cape Hatteras. This recommendation was also made by a group of 
scientists from the University of North Carolina-Wilmington (D.A. 
Pabst, W.A. McLellan, and A.C. Johnson; hereafter, ``Pabst et al.'').
    Response: In this case, NRDC presents substantial evidence of the 
year-round importance of this habitat to marine mammals (evidence cited 
by NMFS in proposing the area as a seasonal closure); we agree that 
this habitat is of year-round importance. We did not base the 
development of this area as a seasonal restriction because of some 
assumption that the area is only important for a portion of the year 
(though the specific seasonal timing is based on increased density of 
sperm whales; see ``Mitigation''). Rather, our development of this area 
as a seasonal restriction was in consideration of practicability under 
the MMPA's least practicable adverse impact standard. We believe NRDC's 
comment inappropriately minimizes the element

[[Page 63303]]

of practicability in a determination of the measures that satisfy the 
standard. In this case, the area is of critical interest to all 
applicants--based on the dated historical survey information from the 
region, this area is considered to potentially be most promising in 
terms of hydrocarbon reserves. Therefore, an absolute proscription on 
any given applicant's ability to collect data in this area would be 
impracticable. In such a case where practicability concerns would 
preclude inclusion of an otherwise valid measure, the measure must be 
necessary to a finding of negligible impact (i.e., the negligible 
impact determination cannot be made and the authorization may not be 
issued absent the measure) in order to supersede the practicability 
concerns. While NRDC presents substantial evidence of the importance of 
this area for the marine mammals that use it, they do not grapple with 
the practicability question or justify why the closure must be year-
round for a negligible impact determination to be made.
    We disagree with NRDC's apparent contention that surveys conducted 
in this region are likely to result in the death of resident beaked 
whales. As we discussed in our Notice of Proposed IHAs, we recognize 
the importance of the concepts described in Forney et al. (2017), i.e., 
that for resident animals, it is possible that displacement may lead to 
effects on foraging efficiency that could impact individual vital 
rates. However, no evidence is presented that severe acute impacts are 
a reasonably anticipated outcome for surveys that will pass through 
such habitat in a matter of days.
    We also disagree with NRDC's summary dismissal of the benefit of 
completely restricting survey activity in the habitat for a portion of 
the year. The benefit of a restriction targeting resident animals is 
sensibly scaled to the duration of the restriction and/or the timing of 
the restriction in relation to reproductive behavior. However, we 
believe that a full season without acute noise exposure, at minimum, 
for those animals will provide meaningful benefit, including but not 
limited to avoidance of the stress responses of concern to NRDC 
elsewhere in their comments.
    Comment: Regarding NMFS's proposed time-area restriction in waters 
off Cape Hatteras, Pabst et al. state that recent data from acoustic 
monitoring suggest that sperm whales are more abundant in this area 
during winter.
    Response: NMFS's initial proposal was to require implementation of 
this restriction from July through September, in recognition of the 
limited available visual survey data. As noted by commenters, visual 
survey data do suggest that sperm whales are most common in the Cape 
Hatteras region in summer (Roberts et al., 2016). The commenters go on 
to note, however, that more recently available acoustic monitoring data 
indicates that the highest number of sperm whale detections were made 
in winter when visual survey effort was most limited (Stanistreet et 
al., 2018). While we disagree with the commenters' larger point, i.e., 
that the ``Hatteras and North'' restriction should be in effect year-
round (addressed in previous comment response), we agree with their 
interpretation of the data that sperm whales are more abundant in 
winter. Upon review of this newly available data, we determined it 
appropriate to revise the timing of this restriction to January through 
March, as described in ``Mitigation.''
    Comment: NRDC, the MMC, and multiple other commenters state that 
NMFS must expand protection of North Atlantic right whale habitat. Many 
commenters referred to the spatial aspect of the proposed restriction, 
though some commenters also referred to the temporal aspect.
    Response: We agree with the comments referencing the spatial 
designation, and we are spatially expanding the seasonal restrictions 
intended to protect right whale migratory habitat, in addition to 
reproductive habitat and for general protection of right whales (or 
requiring that comparable protection is achieved through implementation 
of a NMFS-approved mitigation and monitoring plan at distances between 
47-80 km offshore). Our determination in this regard and development of 
this expanded protection are described in greater detail elsewhere in 
these comment responses, as well as in the section entitled 
``Mitigation.'' However, we disagree that the available evidence 
supports expansion of this area temporally. Pabst et al., in 
recommending a temporal expansion, reference an analysis of the 
composition and distribution of individual right whale sightings 
archived by the North Atlantic Right Whale Consortium from 1998 through 
2015 performed by one of the comment authors. While this analysis (as 
well as more recent acoustic monitoring data; e.g., Davis et al. 
(2017)) suggests that right whales are present in the area in all 
months of the year, it also shows that very few occurred outside of the 
time window and outside of the year-round 30-km coastal restriction. 
During this period, only five archived sightings occurred outside of 
the November through April period and outside of 30 km from shore. 
Further, it would be impracticable to completely close this area to 
survey activity year-round. As we have acknowledged, it is possible 
that whales will be present beyond this area, or that whales will be 
present within this area but at times outside when migration is 
expected to occur. However, we base the time-area restriction on our 
best understanding of where and when most whales will be expected to 
occur.
    Comment: Several industry commenters provided comments regarding 
NMFS's proposed exception to shutdown requirements for certain species 
of dolphin. The Associations stated that, while they appreciate the 
exception, it should apply to all dolphin species, regardless of 
behavior. They add that no shutdowns for dolphins are warranted. CGG 
also criticized the proposed behavior-based exception, instead 
suggesting that a power-down requirement be applied as an alternative. 
CGG favorably stated that such a requirement would ``allow for a 
tolerable hole in the acquired seismic data and will not require the 
vessel to immediately terminate the survey line and carry out a six 
hour circle for infill'' and that use of power-downs rather than 
shutdowns in these circumstances would result in substantial savings in 
operating costs. TGS stated simply that NMFS ``should consider 
clarifying and better addressing bow-riding dolphins'' and also 
recommended that NMFS clarify and better define how to determine if 
animals are stationary (in reference to NMFS's proposed behavior-based 
requirements for dolphins).
    Response: Following review of the available information and public 
comments, NMFS agrees that a general exception to the standard shutdown 
requirement is warranted for small delphinids, without regard to 
behavior. We agree with TGS and other commenters that the intended 
behavior-based exception was poorly defined. However, we do not agree 
that the available evidence supports certain commenters' assertions 
that seismic surveys do not have any adverse effects on dolphin 
species. As discussed in ``Mitigation,'' auditory injury is not 
expected for dolphins, but the reason for dolphin behavior around 
vessels (when they are attracted) is not understood and cannot be 
assumed to be harmless. In fact, the analyses of Barkaszi et al. 
(2012), Stone (2015a), and Stone et al. (2017) show that dolphins do 
avoid working vessels.
    That said, the available information does not suggest that such 
reactions are likely to have meaningful energetic

[[Page 63304]]

effects to individuals such that the effectiveness of such measures 
outweighs the practicability concerns raised by commenters, in terms of 
the operational costs as well as the difficulty of implementation. All 
variations of a conditional shutdown exception proposed to date (by 
either NMFS or BOEM) that include exceptions based on animal behavior 
have been criticized, in part due to the subjective on-the-spot 
decision-making such schemes would require of PSOs. NMFS finds these 
criticisms warranted. If the mitigation requirements are not 
sufficiently clear and objective, the outcome may be differential 
implementation across surveys as informed by individual PSOs' 
experience, background, and/or training. Therefore, the removal of such 
measures for small delphinids is warranted in consideration of the 
available information regarding the effectiveness of such measures in 
mitigating impacts to small delphinids and the practicability of such 
measures.
    As noted above, one commenter suggested that a power-down 
requirement would be practicable (though we note that this alternative 
was offered against the backdrop of broader claims that no measures 
should be required). We considered modifying the behavior-based 
shutdown requirement contained in our proposed IHAs to CGG's suggested 
general power down requirement. However, following consultation with 
applicants and with BOEM, we determined that the circumstances of this 
particular commenter (CGG) with regard to practicability may not be 
broadly transferable, and that a power down requirement would 
potentially lead to the need for termination of survey lines and infill 
of the line where data were not acquired if a power down was performed 
according to accepted practice, in which the power down condition would 
last until the dolphin(s) are no longer observed within the exclusion 
zone. As noted in our Notice of Proposed IHAs, the need to revisit 
missed track line to reacquire data is likely to result 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.
    We disagree with comments that no shutdown requirements should 
apply to any delphinid species, regardless of behavior. Here we refer 
to ``large delphinids'' and ``small delphinids'' as shorthand for 
generally deep-diving versus surface-dwelling/bow-riding groups, 
respectively, although the important distinction is their dive behavior 
rather than their size. As noted above, industry commenters have 
asserted that no shutdown requirements are warranted for any species of 
dolphin, stating that the best available science does not support 
imposing such requirements. The comments acknowledge that small 
delphinids are more likely to approach survey vessels than large 
delphinids, but claim without supporting data that there is no evidence 
that large delphinids will benefit from a shutdown requirement. In 
contrast to the typical behaviors of (and observed effects on) the 
small delphinid species group, the typical deep diving behavior of the 
relatively rarely occurring large delphinid group of species makes 
these animals potentially susceptible to interrupted/delayed feeding 
dives, which can cause energetic losses that accrue to affect fitness. 
As described in greater detail elsewhere in this Notice, there are 
ample data illustrating the responses of deeper diving odontocetes 
(including large delphinids) to loud sound sources (including seismic) 
to include interrupted foraging dives, as well as avoidance with 
increased speed and stroke rate, both of which may contribute to 
energetic costs through lost feeding opportunities and/or increased 
energy demands. Significant advances in study of the population 
consequences of disturbance are informing our understanding of how 
disturbances accrue to effects on individual fitness (reproduction and 
survival) and ultimately to populations via the use of energetic 
models, where data are available for a species, and expert elicitation 
when data are still limited. The link between behavioral disturbance, 
reduced energy budgets, and impacts on reproduction and survival is 
clear, as is the value in reducing the probability or severity of these 
behavioral disturbances where possible. Therefore, we find that there 
is support for the effectiveness of the standard shutdown requirement 
as applied to the large delphinid species group.
    Further, the claim of industry commenters that shutdowns for these 
deep-diving species would be impracticable was not accompanied by 
supporting data. The data available to NMFS demonstrates that this 
requirement is practicable. For example, Barkaszi et al. (2012)'s study 
of observer data in the Gulf of Mexico from 2002-08 (1,440 bi-weekly 
reports) shows that large delphinids were sighted on only 1.4% of 
survey days, and that of these sightings, only 58% were within the 500-
meter exclusion zone.
    Comment: Many commenters expressed concern regarding the efficacy 
of the prescribed visual and acoustic monitoring methods, stating that 
species could go undetected. Some commenters offer specific 
recommendations for changes to staffing requirements. Finally, some of 
these commenters state that NMFS should require operators to cease work 
in low-visibility conditions, because of the difficulty in detecting 
marine mammals in such conditions.
    Response: While we disagree with some specific comments regarding 
efficacy, we agree with the overall point that there are limitations on 
what may reasonably be expected of either visual or acoustic 
monitoring. While visual and acoustic monitoring effectively complement 
each other, and acoustic monitoring is the most effective monitoring 
method during periods of impaired visibility, there is no expectation 
that such methods will detect all marine mammals present. In general, 
commenters appear to misunderstand what we claim with regard to what 
such monitoring may reasonably be expected to accomplish and/or the 
extent to which we rely on assumptions regarding the efficacy of such 
monitoring in reaching the necessary findings. We appropriately 
acknowledge these limitations in prescribing these monitoring 
requirements, while stating why we believe that visual and acoustic 
monitoring, and the related protocols we have prescribed, are an 
appropriate part of the suite of mitigation measures necessary to 
satisfy the MMPA's least practicable adverse impact standard. However, 
our findings of negligible impact and/or small numbers are in no way 
conditioned on any presumption of monitoring efficacy. With regard to 
specific staffing requirements, those prescribed herein are based on 
typical best practices and on review of all available literature 
concerning such practices. Commenters do not offer compelling 
information that their proffered recommendations achieve the 
appropriate balance between enhancement of monitoring effectiveness and 
the costs (including both monetary costs as well as costs in terms of 
berth space), and we retain the requirements originally specified. 
Finally, any requirement to cease operations during low visibility 
conditions, including at night, would not only be plainly 
impracticable, it would also likely result in greater impacts to marine 
mammals, as such a measure would require operations to continue for 
roughly twice the time.

[[Page 63305]]

Such comments do not align with the principles we laid out in the 
``Proposed Mitigation'' section of our Notice of Proposed IHAs, in 
which we discussed the definitively detrimental effects of increased 
time on the water and/or increased or unnecessary emission of sound 
energy into the marine environment, versus the potential and uncertain 
negative effect of proceeding to most efficiently conclude survey 
activity by conducting operations even in low visibility conditions.
    Comment: NRDC asserts that NMFS does not fulfill the MMPA's 
requirement to prescribe mitigation achieving the ``least practicable 
adverse impact'' to marine mammal habitat, and specifically notes that 
NMFS does not separately consider mitigation aimed at reducing impacts 
to marine mammal habitat, as the MMPA requires.
    Response: We disagree. Our discussion of least practicable adverse 
impact points out that because habitat value is informed by marine 
mammal presence and use, in some cases there may be overlap in measures 
for the species or stock and for use of habitat. Here we have 
identified time-area restrictions based on a combination of factors 
that include higher densities and observations of specific important 
behaviors of the animals themselves, but also clearly reflect preferred 
habitat. In addition to being delineated based on physical features 
that drive habitat function (e.g., bathymetric features, among others), 
the high densities and concentration of certain important behaviors 
(e.g., feeding) in these particular areas clearly indicates the 
presence of preferred habitat. Also, NRDC asserts that NMFS must 
``separately'' consider measures aimed at marine mammal habitat. The 
MMPA does not specify that effects to habitat must be mitigated in 
separate measures, and NMFS has clearly identified measures that 
provide significant reduction of impacts to both ``marine mammal 
species and stocks and their habitat,'' as required by the statute. 
Last, we note that NRDC acknowledges that NMFS's measures would reduce 
impacts on ``acoustic habitat.''
    Comment: The MMC recommended that, if NMFS is to require a time-
area restriction to protect spotted dolphins in shelf waters, the 
restriction should be expanded from June through August to June through 
September. This recommendation was made on the basis of spotted 
dolphins likely being most abundant in this area during summer. 
Similarly, TGS stated that NMFS should better support its determination 
of seasonality for the proposed restriction.
    Response: Following review of public comments, NMFS determined that 
this proposed time-area restriction was unlikely to be effective in 
accomplishing its intended purpose, while imposing practicability costs 
on applicants. As explained in greater detail in the ``Mitigation'' 
section, we have eliminated this proposed requirement. Therefore, the 
MMC's recommendation is no longer relevant.
    Comment: NRDC states that NMFS must require larger buffer zones 
around the required time-area restrictions. TGS stated that NMFS should 
better support its choice of 10 km as a buffer distance.
    Response: NRDC provides several reasons why they believe that the 
required standard 10-km buffer zones are insufficient. NRDC claims 
several supposed ``erroneous and misplaced assumptions'' in the sound 
field modeling that informs our standard buffer zone, which we have 
refuted elsewhere in these comment responses. More substantively, NRDC 
returns again to its suggestion that a different threshold must be used 
to represent Level B harassment. We have also addressed this comment 
elsewhere. Here, we reiterate that BOEM's sound field modeling, which 
was conducted in accordance with the best available scientific 
information and methods, and which remains state-of-the-science, 
indicates that the mean distance (considering 21 different scenarios 
combining water depth, season, and bottom type) to the 160-dB isopleth 
would be 6,838 m (range 4,959-9,122 m). Our required 10-km buffer is 
appropriate in conservatively accounting for the potential for sound 
exceeding the 160-dB isopleth.
    Comment: NRDC stated that in order to adequately develop habitat-
based protections for marine mammals, NMFS should, in addition to 
consideration of Roberts et al. (2016) and other relevant information, 
follow certain guidelines to protect baleen whale stocks and other 
marine mammals: (1) Continental shelf waters and waters 100 km seaward 
of the continental slope; (2) waters within 100 km of all islands and 
seamounts that rise within 500 m of the surface; and (3) high 
productivity regions not included under the previous two guidelines. 
Although NRDC's recommendation is unclear, we assume that the commenter 
intends that we designate such areas as year-round closures to survey 
activity.
    Response: NMFS relied on the best available scientific information 
(e.g., Stock Assessment Reports, Roberts et al., 2016, 2017; numerous 
study reports from Navy-funded monitoring and research in the specific 
geographic region) in assessing density, distribution, and other 
information regarding marine mammal use of habitats in the study area. 
In addition, NMFS consulted LaBrecque et al. (2015), which provides a 
specific, detailed assessment of known Biologically Important Areas 
(BIA). Although BIAs are not a regulatory designation, the assessment 
is intended to provide the best available science to help inform 
regulatory and management decisions about some, though not all, 
important cetacean areas. BIAs, which may be region-, species-, and/or 
time-specific, include reproductive areas, feeding areas, migratory 
corridors, and areas in which small and resident populations are 
concentrated. Because the BIA assessment may not include all important 
cetacean areas, NMFS went beyond this evaluation in conducting a core 
abundance analysis for all species on the basis of the Roberts et al. 
(2016) cetacean density models (described in detail in our Notice of 
Proposed IHAs). NMFS then weighed the results of the core abundance 
analysis for each species in context of the anticipated effects of each 
specified activity, other stressors impacting the species, and 
practicability for the applicants in determining the appropriate suite 
of time-area restrictions (see ``Mitigation''). Outside of these time-
area restrictions, NMFS is not aware of any evidence of other habitat 
areas of particular importance, or of any compelling evidence that the 
planned time-area restrictions should be modified in any way when 
benefits to the species and practicability for applicants are 
considered together.
    Regarding NRDC's recommended guidelines, we disagree that these 
would be appropriate for use in determining habitats for protection in 
this circumstance. The guidelines come from a white paper 
(``Identifying Areas of Biological Importance to Cetaceans in Data-Poor 
Regions'') written by NMFS scientists for consideration in identifying 
such areas in relation to mitigation development for the incidental 
take rule governing the U.S. Navy's Surveillance Towed Array Sensor 
System Low Frequency Active (SURTASS LFA) sonar activities, which was 
applicable for much of the world's oceans, including in many so-called 
data-poor areas. NMFS convened a panel of subject matter experts tasked 
with helping to identify areas that met our criteria for offshore 
biologically important areas (OBIAs) for marine mammals relevant to the 
Navy's use of SURTASS LFA sonar, and the white paper offered guidance 
on alternate

[[Page 63306]]

methods for considering data-poor areas, in view of the fact that data 
on cetacean distribution or density do not exist for many areas of the 
world's oceans. However, such is not the case for the specific 
geographic region considered here. In fact, the white paper was 
specifically developed to provide methods for data-poor areas as an 
alternative to use of a global habitat model (Kaschner et al., 2006) 
when such use was determined to result in both errors of omission 
(exclusion of areas of known habitat) and commission (inclusion of 
areas that are not known to be habitat). Here, we do not face the same 
lack of data sufficient to inform the designation of appropriate 
habitat-based restrictions. As described previously, we made use of 
advanced habitat-based predictive density models, an existing 
assessment of BIAs in the region, and a substantial body of data from 
monitoring and research concerning cetacean distribution and habitat 
use in sensitive areas of the region. Finally, were we to follow NRDC's 
apparent recommendation in closing all of the areas covered by the 
guidelines to survey activity, the resulting mitigation would not be 
practicable for applicants, as a substantial portion of the planned 
survey area would not be available.
    Comment: NRDC states that NMFS should consider time-area closures 
for additional species.
    Response: We did consider habitat-based protections for species 
additional to those discussed in the time-area restrictions section of 
``Mitigation.'' For all affected species, we evaluated the 
environmental baseline (i.e., other population-level stressors), the 
nature and degree of effects likely to be the result of the specified 
activities, and the information available to support the development of 
appropriate time-area restrictions. We determined that the available 
information supported development of the measures for the North 
Atlantic right whale, sperm whales, beaked whales, and pilot whales. 
For other species, context does not justify additional protections and/
or the available information does not support the designation of any 
specific area for protection. NRDC suggests that such measures should 
be developed for the humpback whale, sei whale, fin whale, and blue 
whale. However, NRDC neither adequately justifies the recommendation, 
offering only cursory reference to the ongoing humpback whale UME (but 
not referencing the otherwise strong health of the West Indies DPS) and 
summarily providing dire conclusions regarding the supposed effects on 
all baleen whales, notwithstanding that at least two of these species 
(the sei whale and blue whale) are anticipated as being unlikely to 
experience any meaningful impacts from the specified activities. We 
addressed NRDC's recommended use of a 2010 ``white paper'' in the 
previous comment response; other than this apparent recommendation that 
nearly the entirety of the survey area (e.g., continental shelf waters 
and waters 100 km seaward of the continental slope; waters within 100 
km of all islands and seamounts that rise within 500 m of the surface; 
and high productivity regions not included under the previous two 
guidelines) be declared as a protected area, NRDC offers no useful 
recommendation as to the designation of protections for these species. 
Our development of habitat-based protections was conducted 
appropriately in light of relevant information regarding the 
environmental baseline, expected effects of the specified activities, 
and information regarding species use of the planned survey area.
    Comment: NRDC states that our development of time-area restrictions 
was performed inadequately, and Pabst et al. also challenged our use of 
core abundance areas. TGS stated that we should better support our use 
of the 25 percent core abundance area in determining the time-area 
restrictions, and that we should better describe our consideration of 
practicability.
    Response: NRDC's primary complaint is that our use of the ``core 
abundance area'' concept was inadequate, and other commenters appear to 
believe that the core abundance area was the determining factor in the 
delineation of restriction areas. These comments misapprehend our use 
of core abundance areas, as we did not use the core abundance areas to 
define habitat-based protections. To clarify, these core abundance 
areas did not define the designated time-area restrictions, but rather 
informed and supported our definition of the appropriate areas. 
Further, there is no ``correct'' answer regarding the proportion of 
core abundance that should inform development of habitat-based 
protections. In part, our analysis of core abundance areas defined by 
varying proportions of the population simply helped us to adequately 
visualize areas within the specific geographic region that would 
reasonably be expected to protect a substantive portion of the 
population within a relatively well-defined area. In some cases, this 
helped to confirm that stable habitat, i.e., habitat defined by 
bathymetric features rather than dynamic oceanographic characteristics 
and which would be expected to provide important habitat to certain 
species, is indeed predicted to host high abundance of these species.
    NRDC's comment regarding the sperm whale is illustrative. NRDC 
refers simply to the 5 percent core abundance area for sperm whales as 
``entirely inadequate.'' However, when analyzing multiple different 
core abundance areas for the species, we find that it is predicted as 
being broadly distributed over slope waters throughout much of the 
year, i.e., there is little discrete habitat defined in a way that is 
suitable for protection through a restriction on effort. Therefore, we 
did not define the protections on the sole basis of the core abundance 
area analysis. Rather, the core abundance area analysis helped to 
highlight that sperm whales should be expected to be present year-round 
in certain deepwater canyons (which also provide important habitat for 
beaked whales); the spatial definition of these areas does not in fact 
align with the predicted core abundance area, but rather with the 
bathymetric features that provide the conditions that lead to the 
predictions of high abundance in the first place, as is appropriate. 
Separately, the 5 percent core abundance area highlighted that, in 
contrast with the broad slope area over which sperm whales are 
generally expected to occur, a discrete area off of Cape Hatteras 
(i.e., ``The Point'') would be expected to provide attractive habitat 
to sperm whales throughout the year, thus enabling us to include this 
area, with other areas of importance for the sperm whale and other 
species, in the conglomerate ``Hatteras and North'' (Area #4).
    Our definition of the Hatteras and North area was primarily 
informed by review of the available literature (as described in our 
Notice of Proposed IHAs), which shows that, for example, beaked whales 
are consistently present in particular waters of the shelf break region 
at all times of year (e.g., McLellan et al., 2018; Stanistreet et al., 
2017); relatively high numbers of sperm whales are present off of Cape 
Hatteras year-round (but particularly in the winter) (Stanistreet et 
al., 2018); and pilot whales have a strong affinity for the shelf break 
at Cape Hatteras and waters to the north (e.g., Thorne et al., 2017). 
These findings provided a strong indication that the area should be 
afforded some degree of protection in the form of restriction on 
effort, while the core abundance analysis both supported these findings 
and provided a more quantitative basis upon which to delineate the 
specific area.

[[Page 63307]]

    We also acknowledge the important role that practicability for 
applicants plays in defining the appropriate suite of mitigation 
requirements to satisfy the MMPA's least practicable adverse impact 
standard, including design of habitat-based protections. Where a 
negligible impact finding is not conditioned upon the implementation of 
specific mitigation, prescription of mitigation must consider impacts 
on practicability. As stated above, protection of additional habitat 
for the sperm whale--given no basis on which to specify targeted 
protections beyond those included herein--would necessarily involve 
restricting access to large swaths of the specific geographic region. 
Based on our understanding of applicant considerations, such 
significant restrictions would likely lead to an applicant's 
determination that the survey would not take place, as the return on 
investment would not justify the expenditure, i.e., a clear-cut case of 
a fatal practicability issue. In the absence of necessity (i.e., the 
measure must be prescribed in order to make a finding of negligible 
impact), it would not be permissible to require such stringent 
restrictions.
    NRDC goes on to cite ``important passive acoustic detections, 
opportunistic sightings, and other data'' that we have supposedly 
ignored, and cites the New York Bight (an area outside the specific 
geographic region) as an area illustrating the supposed failure of the 
density models to adequately highlight important habitat. NRDC also 
references biologically important areas; as described later in this 
document, we reviewed available information regarding BIAs (LaBrecque 
et al., 2015) and there are no additional identified BIAs in the 
region.
    In summary, and contrary to NRDC's statements, we did not rely 
exclusively on the core abundance analysis to define restriction areas. 
While we may have inadvertently overemphasized this important aspect of 
our process in the description provided in our Notice of Proposed IHAs, 
we evaluated the available literature to inform our understanding of 
rough areas suitable for protection (or characteristics that might 
provide such areas), subsequently refining our analysis through use of 
core abundance analysis to identify specific areas where features 
expected to provide important habitat overlap with actual predictions 
of high abundance and/or to refine the specific boundaries of areas 
that the literature indicated to be of importance. We appropriately 
based our definition of time-area restrictions on the available 
literature as well as on our analysis of core abundance areas.
    Comment: ION requests that we reconsider the proposed time-area 
restrictions, based on a supposed lack of effects to right whales from 
noise exposure, the lack of evidence for serious injury, death, or 
stranding of beaked whales due to noise exposure from airgun surveys, 
and the possibility that deepwater canyon closures could be timed to 
coincide seasonally with the lowest density of sperm whales.
    Response: We refer to the discussions provided in our Notice of 
Proposed IHAs regarding ``Potential Effects of the Specified Activity 
on Marine Mammals'' and detailing the rationale and basis for our 
designation of time-area restrictions in ``Proposed Mitigation.'' We 
stand by this information as supporting our assumptions regarding 
likely effects of marine mammals and the need for such time-area 
restrictions, and regarding the basis upon which we designated specific 
restrictions. Specifically, we have designated the relatively small 
deepwater canyon areas as year-round closures due to the likelihood 
that they provide year-round habitat to beaked whales and possibly 
sperm whales, while resulting in relatively minor practicability 
impacts. ION claims that these three deepwater canyon closures would 
result in ``large gaps in the seismic data acquired,'' but the map 
provided as Figure 1 in ION's letter does not support this contention, 
instead showing that only very small portions of several planned survey 
lines pass through these areas.
    Comment: CGG suggests that NMFS should evaluate observational data 
submitted during the course of the survey and only require time-area 
restrictions ``if potential significance of behavioral disruption and 
potential for longer-term avoidance exists as a result of acoustic 
exposure'' from the survey.
    Response: We disagree that this would be the appropriate approach 
to implementation of required restrictions. We also note that CGG 
mistakenly states that distribution of some species targeted in our 
design of restrictions is modeled through use of stratified models, 
implying that not enough information exists on which to base such 
restrictions. Our restriction areas target coastal bottlenose dolphins, 
North Atlantic right whales, beaked whales, sperm whales, and pilot 
whales, none of which are modeled through stratified models. More 
importantly, the entire premise of time-area restrictions is that, on 
the basis of a reasoned consideration of available information 
regarding the anticipated impacts to the affected species or stocks, 
their status, use of habitat, and practicability for applicants, 
restrictions on survey effort to completely or partially avoid 
sensitive habitat are appropriate. Moreover, it would not be 
appropriate to allow the surveys to occur in those places, thereby 
potentially allowing the impacts to sensitive habitat and/or disruption 
of critical behaviors at important places and/or times, and expect that 
observational data collected during the survey would adequately 
indicate that the restriction should in fact be in place.
    Comment: The Associations state that right whale dynamic management 
areas (DMA) should not be used as operational restriction areas, and 
that areas designated to identify the presence of right whales cannot 
be used for multiple purposes, e.g., to reduce risk of ship strike and 
to avoid harassment.
    Response: The DMA concept recognizes that aggregations of right 
whales can occur outside of areas and times where they predictably and 
consistently occur, and it can be applied in various contexts. The DMA 
construct is used to help reduce risk of ship strike for right whales 
in association with NMFS's regulations for vessel speed limits in 
prescribed ``seasonal management areas'' (73 FR 60173; October 10, 
2008; extended by 78 FR 73726; December 9, 2013). In that regard, when 
a specific aggregation of right whales is sighted, NMFS ``draws'' a 
temporary zone (i.e., DMA) around the aggregation and alerts mariners. 
DMAs are in effect for 15 days when designated and automatically expire 
at the end of the period, but may be extended if whales are re-sighted 
in the same area.
    The DMA concept also was used between 2002 and 2009 to protect 
unexpected aggregations of right whales that met an appropriate trigger 
by temporarily restricting lobster trap/pot and anchored gillnet 
fishing in the designated area (gear modifications have since replaced 
those requirements).
    As we have stated, it is critically important to avoid impacts to 
right whales when possible and to minimize impacts when they do occur. 
Because DMAs identify aggregations of right whales, it is appropriate 
to restrict operations in these areas when DMAs are in effect. While we 
acknowledge that this requirement will impose operational costs, if the 
establishment of a DMA results in the need for a survey to temporarily 
move to another location, such concerns are weighted appropriately here 
in determining that this measure should be included in the suite of 
mitigation necessary to achieve the least practicable adverse impact.

[[Page 63308]]

    Comment: ION suggests that NMFS reconsider its position on use of 
mitigation sources and power-downs, i.e., that NMFS should allow these 
approaches to reduce operational impacts of required mitigation.
    Response: We maintain that use of a ``mitigation source''--commonly 
understood to involve firing of a single airgun for extended periods of 
time to avoid the need for pre-clearance and/or ramp-up--is 
inappropriate here. Our position on this is not based on a lack of 
evidence that the mitigation source would be effective--indeed, we 
agree that it is reasonable to assume some degree of efficacy for a 
mitigation gun in providing a ``warning'' to marine mammals, as we 
discuss in reference to use of ramp-up. Our determination is instead 
based on a consideration that unnecessary introduction of sound energy 
into the water, as occurs during use of a mitigation source, is 
necessarily a deleterious impact, whereas the alternative--allowance of 
start-up at times of poor visibility--may result in negative impacts to 
individual marine mammals in the vicinity, but this is not certain.
    Comment: Several commenters criticized our proposal to require 
shutdowns upon detection of certain species or circumstances (e.g., 
beaked whales, right whales, whales with calves) at any distance. The 
Associations suggest that such requirements are ``unreasonable'' 
because they require shutdowns ``for circumstances in which no Level A 
or Level B harassment will occur,'' and recommend that such measures be 
limited to power-down only for detections within 1,000 m. The 
Associations also contend that these measures will have negative 
impacts on the effectiveness of visual PSOs, stating that the result 
would be that ``observers will be constantly monitoring an unlimited 
zone, which [ . . . ] may undermine the effectiveness of their 
monitoring of the 1,000 m zone.'' CGG makes similar claims, adding that 
these measures would result in a substantial increase in operating 
costs.
    Response: We first note that the minimum Level B harassment zone 
for any survey, in any location, would be beyond the likely detection 
distance for visual observers, even under ideal conditions, e.g., the 
smallest threshold radius out of 21 modeled scenarios from BOEM's PEIS 
was almost 5 km. Therefore, the Associations' claim that shutdowns at 
any distance would occur in circumstances where there is no harassment 
is incorrect. Overall, we disagree with these comments, as well as 
those specific comments we respond to below, which assert that such 
measures are not warranted. In these cases, we have identified species 
or circumstances with particular sensitivities (in conjunction with, in 
some cases, a high magnitude of authorized take) for which we believe 
it appropriate to minimize the duration and intensity of the behavioral 
disruption, as well as to minimize the potential for auditory injury 
(for low- and high-frequency cetaceans). However, while we also 
disagree that trained, experienced professional PSOs would somehow 
misunderstand our intent and spend undue time focusing observational 
effort at distances beyond approximately 1,000 m from the acoustic 
source (i.e., the zone within which we assume that monitoring is 
typically focused, though not necessarily exclusively), in order to 
ensure that this potential is minimized, and to alleviate to some 
degree the operational cost associated with shutdowns at any distance, 
we limit these shutdowns to within 1.5 km (versus at any distance). The 
rationale for this distance is explained later in this document in 
``Mitigation.''
    Comment: Several commenters criticized the proposal to require 
shutdowns based upon aggregations of six or more marine mammals in a 
state of travel, stating that such a measure is ``vague and unbounded'' 
and would be impracticable due to the large number of shutdowns that 
may result.
    Response: We acknowledge that this measure, as described in our 
Notice of Proposed IHAs, does not likely carry benefits commensurate 
with the likely costs and is therefore impracticable. However, the 
provided description was in error in that it inadvertently suggested 
requirements beyond what we intended, i.e., we did not intend that this 
measure would apply to species that commonly occur in large groups, 
such as dolphins. We have modified this requirement to clearly state 
that it applies only to aggregations of large whales (i.e., baleen 
whales and sperm whales), and to eliminate the behavioral aspect of the 
requirement, as recommended by commenters. Contrary to claims of 
commenters, this measure (as clarified/revised) is warranted, in that 
minimization of disruption for aggregations of resting and/or 
socializing whales is important and also practicable. As described 
above, the shutdown requirement is bounded by a maximum distance of 1.5 
km.
    Comment: Multiple industry commenters criticized the proposed 
requirement for shutdowns upon observation of a diving sperm whale 
centered on the forward track of the source vessel, stating that the 
proposal was unclear and likely unworkable.
    Response: We agree with commenters (though we disagree with 
associated, unsupported statements regarding lack of effects to sperm 
whales), and have removed this measure.
    Comment: TGS stated that we should remove the requirement (specific 
to TGS) to shut down upon observation of any fin whale.
    Response: For reasons described in greater detail in the section 
entitled ``Mitigation,'' we agree with this comment and have removed 
the measure.
    Comment: The Associations and other industry commenters state that 
the requirement for shutdowns upon observation of large whales with 
calf is not warranted and will be ``very impracticable because of the 
large number of . . . shutdowns it will generate.''
    Response: We disagree with these comments and retain this 
requirement, albeit within the 1.5 km zone versus ``at any distance.'' 
As we discuss in the ``Mitigation'' section, groups of whales are 
likely to be more susceptible to disturbance when calves are present 
(e.g., Bauer et al., 1993), and disturbance of cow-calf pairs could 
potentially result in separation of vulnerable calves from adults. 
Separation, if it occurred, could be exacerbated by airgun signals 
masking communication between adults and the separated calf (Videsen et 
al., 2017). Absent separation, airgun signals can disrupt or mask 
vocalizations essential to mother-calf interactions. Given the 
consequences of potential loss of calves in context of ongoing UMEs for 
multiple mysticete species, as well as the functional sensitivity of 
the mysticete whales to frequencies associated with airgun survey 
activity, we believe this measure is warranted by the MMPA's least 
practicable adverse impact standard. Commenters provide no 
justification for the claim that this measure will result in a large 
number of shutdowns.
    Comment: Several industry commenters also suggest that there is not 
adequate justification for enhanced shutdown requirements for right 
whales, beaked whales, or Kogia spp. These commenters all provide the 
same points verbatim (paraphrased here): (1) Because the primary threat 
facing right whales are entanglement with fishing gear and ship 
strikes, enhanced shutdowns have no impact on the causes of right whale 
decline; (2) while acknowledging that beaked whales are acoustically 
sensitive, they claim that evidence does not exist regarding

[[Page 63309]]

sensitivity to airgun noise; and (3) Kogia spp. are grouped with high-
frequency cetaceans (and thus are subject to greater propensity for 
auditory injury) on the basis of studies of harbor porpoise; therefore, 
this classification is invalid.
    Response: These claims lack merit, and we retain these requirements 
(albeit within the 1.5 km zone versus ``at any distance''). We agree 
that the primary threats to right whales are entanglement and ship 
strike, but the deteriorating status of the population (discussed in 
detail in the section entitled ``Description of Marine Mammals in the 
Area of the Specified Activities'') indicates that impacts to 
individual right whales should be avoided where possible and otherwise 
minimized. The preponderance of evidence clearly demonstrates that 
beaked whales are acoustically sensitive species. While beaked whale 
stranding events have been associated with use of tactical sonar, 
indicating that this specific noise source may be more likely to result 
in behaviorally-mediated mortality, the lack of such association with 
airgun surveys does not mean that beaked whales are less acoustically 
sensitive to the noise source. The same holds for Kogia spp., albeit 
with less evidence for these cryptic species. However, commenters' 
claim regarding the classification of these species into the high-
frequency hearing group holds no merit. The best available scientific 
information, while limited, indicates that these species are 
appropriately classed as high-frequency cetaceans; commenters provide 
no evidence to the contrary. While no data exists regarding Kogia spp. 
hearing, these species were appropriately classified as high-frequency 
cetaceans by Southall et al. (2007) on the basis of high-frequency 
components of their vocalizations. More recent data confirms that Kogia 
spp. use high-frequency clicks (Merkens et al., 2018) and, by 
extension, that their classification as high-frequency cetaceans is 
appropriate.
    Comment: The MMC recommends that NMFS require shutdowns upon 
acoustic detection of sperm whales, as is required for beaked whales 
and Kogia spp.
    Response: We agree with the MMC that shutdowns due to the presence 
of sperm whales should not be limited to visual detection alone. This 
recommendation appears to reflect some ambiguity in the description of 
proposed mitigation provided in our Notice of Proposed IHAs, as it was 
our intent to prescribe mitigation in accordance with this 
recommendation. In conjunction with modifications to the proposed 
mitigation (described in full in the section entitled ``Mitigation''), 
we require that shutdowns be implemented upon confirmed acoustic 
detection of any species (other than delphinids) within the relevant 
exclusion zone.
    Comment: NRDC and other commenters state that NMFS should prescribe 
requirements for use of ``noise-quieting'' technology. NRDC elaborates 
that in addition to requiring noise-quieting technology (or setting a 
standard for ``noise output''), NMFS should ``prescribe targets to 
drive research, development, and adoption of alternatives to 
conventional airguns.''
    Response: We agree with commenters that development and use of 
quieting technologies, or technologies that otherwise reduce the 
environmental impact of geophysical surveys, is a laudable objective 
and may be warranted in some cases. However, here the recommended 
requirements are either not practicable or are not within NMFS's 
authority to require. To some degree, NRDC misunderstands our 
discussion of this issue as presented in our Notice of Proposed IHAs. 
We recognize, for example, that certain technologies, including the 
Bolt eSource airgun, are commercially available, and that certain 
techniques such as operation of the array in ``popcorn'' mode may 
reduce impacts when viable, depending on survey design and objectives. 
However, a requirement to use different technology from that planned or 
specified by an applicant--for example, a requirement to use the Bolt 
eSource airgun--would necessarily require an impracticable expenditure 
to replace the airguns planned for use. NRDC offers no explanation for 
why such an incredible cost imposition (in the millions of dollars) 
should be considered practicable. Separately, NRDC appears to suggest 
that NMFS must require or otherwise incentivize the development of 
wholly new or currently experimental technologies. In summary, while we 
agree that noise quieting technology is beneficial, the suggestions put 
forward by commenters are either impracticable or outside the authority 
provided to NMFS by the MMPA. However, NMFS would consider 
participating in related efforts by NRDC or any other commenter 
interested in these technologies.
    Comment: NRDC claims that NMFS fails to consider mitigation to 
reduce ship strike in right whale habitat. Separately, NRDC states that 
NMFS should consider extending ship-speed requirements to all project 
vessels within ``the North Atlantic right whale BIA.''
    Response: We disagree with NRDC's contention. All project vessels 
are required to adhere to vessel speed requirements. Indeed, the ship 
speed restrictions in these IHAs are required of all vessels associated 
with the surveys, regardless of length, whereas NMFS's ship speed 
regulations apply only to vessels greater than 65 ft in length. We 
agree with NRDC that ship speed requirements are warranted for all 
project vessels in designated areas to minimize risk of strike for 
right whales. However, we are unclear what specific area NRDC may mean 
in referencing ``the North Atlantic right whale BIA.'' We require that 
all project vessels adhere to a 10-kn speed restriction when in any 
seasonal or dynamic management area, or critical habitat.
    Comment: Industry commenters were unanimous in expressing concern 
regarding required vessel strike avoidance mitigation measures, notably 
regarding safety for operators. In particular, recommendations to 
reduce speed and shift engines to neutral in certain circumstances were 
viewed as unsafe for vessels towing gear.
    Response: We agree with the concerns expressed by commenters, and 
clarify that it was not our intent to require such measures for vessels 
towing gear. Safety of human life is paramount, and where legitimate 
concerns exist we agree that required mitigation must reflect such 
concerns. We have revised our discussion of vessel strike avoidance 
measures (see ``Mitigation'') to clarify that the primary requirements 
are (1) all vessels must observe a 10-kn speed limit when transiting 
right whale critical habitat, SMAs, or DMAs, and (2) all vessels must 
observe separation distances identified in ``Mitigation,'' to the 
extent practicable as relates to safety. These requirements do not 
apply to the extent that a vessel is restricted in its ability to 
maneuver and, because of the restriction, cannot comply or in any case 
where compliance would create an imminent and serious threat to a 
person or vessel. Speed alterations (aside from the 10-kn restriction, 
when applicable), alterations in course, and shifting engines to 
neutral are recommendations for how separation distances may be 
achieved but are not requirements, and do not apply to any vessel 
towing gear.
    Comment: ION requests clarification on specific ``precautionary 
measures'' required in order to minimize potential for vessel strike, 
citing the following text from our Notice of Proposed IHAs: ``Vessel 
speeds must also be reduced to 10 kn or less when mother/calf pairs, 
pods, or large assemblages of cetaceans are observed near a vessel. A 
single

[[Page 63310]]

cetacean at the surface may indicate the presence of submerged animals 
in the vicinity of the vessel; therefore, precautionary measures should 
be exercised when an animal is observed.''
    Response: We clarify here that the latter statement, i.e., 
``precautionary measures should be exercised when an animal is 
observed,'' carries no specific requirements. We intend only that 
vessel operators act cautiously in accordance with established 
practices of seamanship to avoid striking observed animals. The 
requirements of the former statement, i.e., that vessel speeds must be 
reduced when mother/calf pairs, pods, or large assemblages of cetaceans 
are observed near a vessel, applies only to those specific 
circumstances, i.e., not in speculative fashion if a single animal or 
small group of animals is observed.
    Comment: One individual stated that NMFS should require applicants 
to monitor propagation conditions, suggesting that this could be 
accomplished through use of conductivity, temperature, and depth (CTD) 
measurement devices, and that vessels should not be allowed to operate 
when propagation is ``exceptionally efficient.''
    Response: The commenter does not specify what propagation 
conditions should be considered ``exceptionally efficient.'' 
Regardless, we do not agree that such a requirement is warranted. The 
sound field modeling conducted by BOEM and by the applicants that did 
not make use of BOEM's modeling is purposely designed to reflect a 
reasonable range of propagation conditions that are expected to be 
encountered in the region. This does not mean that there will never be 
unexpected conditions that may result in propagation beyond the modeled 
distances. However, this potential does not require that operators 
cease operating, as such a requirement would be fraught with 
uncertainty and potentially result in significant additional operating 
costs.
    Comment: NRDC makes several recommendations relating to the use of 
ramp-up.
    Response: First, NRDC states that NMFS should require that ramp-up 
occur over several stages in order to minimize exposure. We agree with 
NRDC on this point, but are confused by the recommendation, which 
appears to restate the ramp-up procedures described by NMFS in our 
Notice of Proposed IHAs. Second, NRDC states that we ``should give 
greater consideration to the requirements that apply after shutdown 
periods.'' Again, we are unclear as to what NRDC's specific 
recommendation is, but NRDC appears to criticize the allowance of an 
array restart without ramp-up, assuming that constant observation has 
been maintained without marine mammal detection. NRDC does not state 
what they believe to be the problem with this allowance, and we believe 
that it is consistent with current practice and appropriate in context 
of the ``least practicable adverse impact.'' Finally, NRDC asserts that 
the half-hour cutoff ``perversely incentivizes'' continuous firing to 
avoid the delay of pre-clearance and ramp-up. This is another confusing 
statement, as we explicitly disallow airgun firing when not necessary 
for data acquisition, e.g., during line turns.
    Comment: NRDC complains that the standard 500-m exclusion zone is 
``plainly insufficient to prevent auditory injury,'' and many other 
commenters echo these comments regarding the sufficiency of the 
prescribed exclusion and buffer zones.
    Response: We have acknowledged that some limited occurrence of 
auditory injury is likely, for low- and high-frequency cetaceans. 
However, we disagree that a larger standard exclusion zone is 
warranted. As we explained in our Notice of Proposed IHAs, our intent 
in prescribing a standard exclusion zone distance is to (1) encompass 
zones for most species 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 and ease of implementation 
for PSOs, who need to monitor and implement the exclusion zone; and (4) 
to define a distance within which detection probabilities are 
reasonably high for most species under typical conditions. Our use of 
500 m as the zone is not based directly on any quantitative 
understanding of the range at which auditory injury would be entirely 
precluded or any range specifically related to disruption of behavioral 
patterns. Rather, we believe it is a reasonable combination of factors. 
In summary, a practicable criterion such as this has the advantage of 
familiarity and simplicity while still providing in most cases a zone 
larger than relevant auditory injury zones, given realistic movement of 
source and receiver. Increased shutdowns, without a firm idea of the 
outcome the measure seeks to avoid, simply displace survey activity in 
time and increase the total duration of acoustic influence as well as 
total sound energy in the water (a goal we believe NRDC supports).
    We agree that, when practicable, the exclusion zone should 
encompass distances within which auditory injury is expected to occur 
on the basis of instantaneous exposure. For high-frequency cetaceans, 
these distances range from 355-562 m for four of the five applicants 
(Table 5). For Spectrum, the predicted distance is significantly larger 
(1,585 m). However, we require an extended exclusion zone of 1.5 km for 
certain sensitive species, including Kogia spp. This means that only 
one rarely occurring species (harbor porpoise), and for only one 
applicant, is left unprotected from potential auditory injury in terms 
of the prescribed distance of the exclusion zone. Moreover, it is 
unlikely that harbor porpoise would even be detected at distances 
greater than 500 m. Potential auditory injury for low-frequency 
cetaceans is based on the accumulation of energy, and is therefore not 
a straightforward consideration. For example, observation of a whale at 
the distance calculated as being the ``injury zone'' does not 
necessarily mean that the animal has in fact incurred auditory injury. 
Rather, the animal would have to be at the calculated distance (or 
closer) as the mobile source approaches, passes, and recedes from the 
exposed animal, being exposed to and accumulating energy from airgun 
pulses the entire time, as is implied by the name of the ``safe 
distance'' methodology by which such zone distances are calculated. 
Therefore, we disagree that it is sensible to create a larger exclusion 
zone on the basis of the calculated injury zones (although we note that 
the extended 1.5 km exclusion zone is required for right whales). We 
also note that the maximum distance cited by NRDC (4,766 m) was an 
error in our Notice of Proposed IHAs (corrected later in this document; 
see ``Level A harassment'' in the ``Estimated Take'' section). In fact, 
the calculated injury distances for two applicants are less than the 
standard 500-m zone, while those calculated for the remaining three 
applicants range from 757-951 m. In keeping with the four broad goals 
outlined above, and in context of the information given here, our 
standard 500-m exclusion zone is appropriate.
    Comment: Several industry commenters criticized the requirement for 
use of a buffer zone, in addition to the standard 500-m exclusion zone, 
claiming in part that use of such a buffer is ``counterintuitive.''

[[Page 63311]]

    Response: Having received multiple comments indicating confusion 
regarding the proposed measure, we first clarify that the requirement 
is for a 500-m buffer zone in addition to the 500-m standard exclusion 
zone, i.e., total typical monitoring zone of 1,000 m, and that the 
implementation of this requirement relates primarily to the pre-
clearance period, when the full 1,000-m zone must be clear of marine 
mammals prior to beginning ramp-up. During full-power firing, the 
buffer zone serves only as a sort of ``warning'' area, where the 
observation of marine mammals should incite readiness to shut down, 
should those animals enter the 500-m shutdown zone.
    We disagree that this measure is counterintuitive, an assertion 
based on the apparent sense that a larger zone should be in effect when 
the array is firing and a smaller zone prior to firing. On the 
contrary, we believe it important to implement a larger zone during 
pre-clearance, when na[iuml]ve animals may be present and potentially 
subject to severe behavioral reactions if airguns begin firing at close 
range. While the delineation of zones is typically associated with 
shutdown, the period during which use of the acoustic source is being 
initiated is critical, and in order to avoid more severe behavioral 
reactions it is important to be cautionary regarding marine mammal 
presence in the vicinity when the source is turned on. This requirement 
has broad acceptance in other required protocols: The Brazilian 
Institute of the Environment and Natural Resources requires a 1,000-m 
pre-clearance zone (IBAMA, 2005), the New Zealand Department of 
Conservation requires that a 1,000-m zone be monitored as both a pre-
clearance and a shutdown zone for most species (DOC, 2013), and the 
Australian Department of the Environment, Water, Heritage and the Arts 
requires an even more protective scheme, in which a 2,000-m ``power 
down'' zone is maintained for higher-power surveys (DEWHA, 2008). 
Broker et al. (2015) describe the use of a precautionary 2-km exclusion 
zone in the absence of sound source verification (SSV), with a minimum 
zone radius of 1 km (regardless of SSV results). We believe that the 
simple doubling of the exclusion zone required here is appropriate for 
use as a pre-clearance zone.
    Comment: In writing about the exception made for dolphins from the 
shutdown requirements, NRDC states that ``more analysis is . . . needed 
of the potential costs and benefits of excluding bow-riding dolphins 
from the exclusion zone requirement.''
    Response: We recognize the concerns raised by NRDC, and agree that 
the reasons for bow-riding behavior are unknown and, further, that in 
context of an active airgun array, the behavior cannot be assumed to be 
harmless. However, dolphins have a relatively high threshold for the 
onset of auditory injury and, for small delphinids, more severe adverse 
behavioral responses are less likely given the evidence of purposeful 
approach and/or maintenance of proximity to vessels with operating 
airguns. With regard to the former point, Finneran et al. (2015) 
exposed bottlenose dolphins to repeated pulses from an airgun and 
measured no TTS. Therefore, the biological benefits of shutting down 
for small delphinids are expected to be comparatively low, whereas, as 
indicated through public comment on these proposed actions, the costs 
of the shutdowns for survey operators is high. Therefore, our 
consideration of this subject, as addressed in an earlier comment 
response, indicates that a general (rather than behavior-based) small 
delphinid exception to the standard shutdown requirement is an 
appropriate part of the suite of mitigation measures necessary to 
effect the least practicable adverse impact.
    Comment: One individual stated that NMFS should require ``trackline 
design'' that minimizes the potential for stranding, including by 
requiring that companies run their nearshore lines at times of reduced 
propagation efficiency.
    Response: The commenter does not specify what is meant by 
``nearshore,'' but we prescribe a year-round 30-km standoff from the 
coast. We assume that 30 km is sufficient to accomplish the commenter's 
objective in making the recommendation.
    Comment: The Associations and other industry commenters raise 
several concerns regarding the PSO requirements. These are: (1) Concern 
regarding NMFS's requirement to review PSO qualifications and 
associated potential for delay, with accompanying recommendation that 
such reviews be ``bounded by some reasonably short time period, with 
the default being that the observer is approved if NMFS fails to 
respond within that time period''; (2) concern whether vessels can 
``safely accommodate'' the number of PSOs required by NMFS's staffing 
requirements; and (3) a claim that NMFS's requirements for PSOs will 
result in labor shortages, and an accompanying recommendation that 
these be ``guidelines'' rather than requirements.
    Response: We agree with the first concern, and have clarified that 
NMFS will have one week to review PSO qualifications (from the time 
that NMFS confirms that adequate information has been submitted) and 
either approve or reject a PSO. If NMFS does not respond within this 
time, any PSO meeting the minimum requirements would automatically be 
approved.
    We disagree with the remainder of the statement. NMFS has evaluated 
the appropriate PSO staffing requirements, as described in 
``Mitigation,'' and we have determined that a minimum of two visual 
PSOs must be on duty at all times during daylight hours in order to 
adequately ensure visual coverage of the area around the source vessel. 
Applicants must account for these requirements in selecting vessels 
that will be suitable for their planned surveys. The Associations' 
third point contains an apparent misconception, in that not all PSOs 
must have a minimum of 90 days at-sea experience, with no more than 18 
months elapsed since the conclusion of the relevant experience. As 
described in our Notice of Proposed IHAs and herein, a minimum of one 
visual PSO and two acoustic PSOs must have such experience (rather than 
all PSOs). The Associations also apparently believe that a requirement 
for professional biological observers to be ``trained biologists with 
experience or training in the field identification of marine mammals, 
including the identification of behaviors'' is a ``rigid restriction.'' 
We respectfully disagree with these claims, and note that no labor 
shortage was experienced in the Gulf of Mexico during 2013-2015 when a 
significantly greater amount of survey activity (i.e., as many as 30 
source vessels) was occurring than is considered here, with 
requirements similar to those described here. NMFS has discussed the 
PSO requirements specified herein with the Bureau of Safety and 
Environmental Enforcement (BSEE) and with third-party observer 
providers; these parties have indicated that the requirements should 
not be expected to result in any labor shortage.
    Comment: The Associations recommend that passive acoustic 
monitoring should be optional, citing operational costs. ION also 
challenges the efficacy of PAM.
    Response: We agree with the Associations that PAM complements 
(rather than replaces) traditional visual monitoring. However, it is 
now considered to be a critical component of real-time mitigation 
monitoring in the majority of circumstances for deep penetration airgun 
surveys. Acoustic monitoring supplants visual monitoring

[[Page 63312]]

during periods of poor visibility and supplements during periods of 
good visibility. As such, we strongly disagree with the Associations' 
outdated recommendation.
    There are multiple explanations of how marine mammals could be in a 
shutdown zone and yet go undetected by observers. Animals are missed 
because they are underwater (availability bias) or because they are 
available to be seen, but are missed by observers (perception and 
detection biases) (e.g., Marsh and Sinclair, 1989). Negative bias on 
perception or detection of an available animal may result from 
environmental conditions, limitations inherent to the observation 
platform, or observer ability. Species vary widely in the inherent 
characteristics that inform expected bias on their availability for 
detection or the extent to which availability bias is convolved with 
detection bias (e.g., Barlow and Forney (2007) estimate probabilities 
of detecting an animal directly on a transect line (g(0)), ranging from 
0.23 for small groups of Cuvier's beaked whales to 0.97 for large 
groups of dolphins). Typical dive times range widely, from just a few 
minutes to more than 45 minutes for sperm whales (Jochens et al., 2008; 
Watwood et al., 2006), while g(0) for cryptic species such as Kogia 
spp. declines more rapidly with increasing Beaufort sea state than it 
does for other species (Barlow, 2015). Barlow and Gisiner (2006) 
estimated that when weather and daylight considerations were taken into 
account, visual monitoring would detect fewer than two percent of 
beaked whales that were directly in the path of the ship. PAM can be 
expected to improve on that performance, and has been used effectively 
as a mitigation tool by operators in the Gulf of Mexico since at least 
2012.
    We expect that PAM technology will continue to develop and improve, 
and look forward in the near-term to the establishment of formal 
standards regarding specifications for hardware, software, and operator 
training requirements, under the auspices of the Acoustical Society of 
America's (ASA) Accredited Standards Committee on Animal Bioacoustics 
(ANSI S3/SC1/WG3; ``Towed Array Passive Acoustic Operations for 
Bioacoustics Applications''). In short, we expect that PAM will 
continue to be an integral component of mandatory mitigation monitoring 
for deep penetration airgun surveys conducted in compliance with the 
MMPA.
    Comment: Several industry commenters expressed concern regarding 
the potential for a large amount of shutdowns due to acoustic 
detections of marine mammals in circumstances where the PAM operator is 
unable to identify the detected species or is unable to determine the 
location of the detected species in relation to the relevant exclusion 
zone.
    Response: NMFS recognizes these concerns, and appreciates the 
comments; however, these potential outcomes would be contrary to NMFS's 
intent in prescribing the use of PAM. Upon review of these comments, we 
find that our description of PAM use was unclear and offer 
clarification here. In the event of acoustic detection, shutdown must 
be implemented only when the PAM operator determined, on the basis of 
best professional judgment, that shutdown is required for the detected 
species and that the species is likely within the relevant exclusion 
zone. For example, although shutdown is required for certain genera of 
large delphinids, we do not require shutdown upon acoustic detection of 
any delphinid, as we do not expect that a PAM operator would likely be 
capable of distinguishing a detected delphinid to species. As in all 
cases, the detection would be communicated to visual observers (if on 
duty); if the detected animal(s) are observed visually, shutdown may be 
required depending on the species. Similarly, we clarify that the 
shutdowns required upon observation of a large whale with calf or an 
aggregation of six or more large whales are for visual observation 
only; a PAM operator cannot be expected to determine on the basis of 
acoustic detection whether a detected whale is with calf or is part of 
an aggregation of six or more. Our intent is not to be overly 
prescriptive, but to empower trained PAM operators to employ 
professional judgment in determining whether shutdown is required in 
the event of acoustic detection. That is, we neither require 
precautionary shutdowns based on acoustic detections when either the 
species or location cannot be determined, nor do we require absolute 
certainty that the detected animal is within the relevant exclusion 
zone if the PAM operator determines that the animal is most likely 
within the zone on the basis of professional judgment.
    Comment: ION recommends that NMFS extend the timeframe for 
operation of the acoustic source during repair of the PAM system in the 
event of malfunction.
    Response: We believe that the requirements regarding conditions 
under which a survey is allowed to continue in the event of PAM 
malfunction are appropriate. These conditions, which are based on 
established protocols required in New Zealand, have been implemented in 
other locations with no known reports of undue hardship. We also note 
that ION does not recommend any alternative. We will be open to 
considering alternatives in the future, but retain these requirements 
here.
    Comment: ION questions NMFS's intentions regarding pre-clearance 
requirements at nighttime, requesting that NMFS clarify that 
observation with PAM satisfies this requirement.
    Response: Ramp-up of the acoustic source, when necessary, may occur 
at times of poor visibility (including nighttime), assuming that a pre-
clearance period has been observed. If the pre-clearance period occurs 
at nighttime, the pre-clearance watch would be conducted only by the 
acoustic observer. We clarify that, indeed, observation with PAM 
satisfies the pre-clearance watch requirement at night.
    Comment: TGS requests clarification of what they interpret as 
contradictory instructions with regard to when visual observations must 
occur.
    Response: We clarify here that visual observation, i.e., two visual 
PSOs on duty, is required during all daylight hours (30 minutes prior 
to sunrise through 30 minutes following sunset, regardless of 
visibility) when use of the acoustic source is planned, from 30 minutes 
prior to ramp-up through one hour after ceasing use of the source (or 
until 30 minutes after sunset). In addition, visual observation is to 
occur 30 minutes prior to and during nighttime ramp-up.
    Comment: NRDC suggests that NMFS should consider requiring use of 
thermal detection as a supplement to visual monitoring.
    Response: We appreciate the suggestion and agree that relatively 
new thermal detection platforms have shown promising results. Following 
review of NRDC's letter, we considered these and other supplemental 
platforms as suggested. However, to our knowledge, there is no clear 
guidance available for operators regarding characteristics of effective 
systems, and the detection systems cited by NRDC are typically 
extremely expensive, and are therefore considered impracticable for use 
in most surveys. For example, one system cited by NRDC (Zitterbart et 
al., 2013)--a spinning infrared camera and an algorithm that detects 
whale blows on the basis of their thermal signature--was tested through 
funding provided by the German government and, according to the author 
at a 2015 workshop concerning mitigation and monitoring

[[Page 63313]]

for seismic surveys, the system costs hundreds of thousands of dollars. 
We are not aware of its use in any commercial application. Further, 
these systems have limitations, as performance may be limited by 
conditions such as fog, precipitation, sea state, glare, water- and 
air-temperatures and ambient brightness, and the successful results 
obtained to date reflect a limited range of environmental conditions 
and species. NRDC does not provide specific suggestions with regard to 
recommended systems or characteristics of systems. We do not consider 
requirements to use systems such as those recommended by NRDC to 
currently be practicable.
    Comment: Mysticetus, LLC (Mysticetus) recommends that all operators 
be required to use a ``modern PSO software system'' for structured data 
collection, real-time situational awareness and computerized mitigation 
decision support. They also list their recommended minimum requirements 
for a PSO software system. Mysticetus also recommends the creation of a 
centralized cloud-based database to hold all PSO-gathered data from all 
survey operations, and states that it should be a requirement of all 
operators to have their PSO software automatically upload data to this 
system on a regular schedule. Separately, we received a comment letter 
from P.N. Halpin of Duke University's Marine Geospatial Ecology Lab; 
the commenter provides support for the recommendation to create a 
cloud-based storage system to store and provide public access to PSO 
data and confirms that the OBIS-SEAMAP team has agreed in principle to 
host and disseminate such a proposed database. Mysticetus goes on to 
provide a number of detailed recommendations relating to how our notice 
might describe the capabilities of a PSO software system, such as is 
recommended for mandatory use, in relation to our proposed mitigation 
and monitoring requirements.
    Response: We appreciate commenters' careful attention to 
improvement of required mitigation and monitoring and for their 
recommendations. We also appreciate the capabilities of ``modern PSO 
software'' described by Mysticetus, including the Mysticetus System 
marketed by Mysticetus, LLC. We agree that such systems may be 
advantageous for the operators, as well as for NMFS and for the public. 
However, we disagree that NMFS must mandate that one specific software 
system be used to accomplish the goals of the required mitigation and 
monitoring, so long as the requirements for mitigation, monitoring, and 
reporting are met.
    Comment: The MMC stated that it supports our proposed requirement 
relating to corrections of sightings data using detection 
probabilities, in order to estimate numbers of actual incidents of 
marine mammal take. However, the MMC also suggests that our proposed 
use of Carr et al. (2011) is not the most appropriate source of such 
probability values, and suggests that we instead base this approach on 
Barlow (2015). In addition, the MMC points out that we did not 
explicitly state that we also intend to account for unobserved areas, 
and provided a recommended extrapolation method.
    Response: We agree with the MMC's statements on this topic and 
thank them for the helpful suggestions. Although, after review of 
public comments, we do not require the applicants to conduct these 
analyses themselves (described in greater detail in the section 
entitled ``Monitoring and Reporting''), we intend to adopt the MMC's 
recommended approach in performing this analysis. We will report these 
corrected results in association with comprehensive reporting from the 
applicants.
    Comment: NRDC asserts that NMFS fails to prescribe requirements 
sufficient to monitor and report takings of marine mammals, and further 
draws a comparison to ``related compliance in the Gulf of Mexico'' 
where they state that ``BOEM is developing an adaptive management 
program, which, beyond `the standard' safety zone monitoring and 
reporting requirements, may include `visual or acoustic observation of 
animals, new or ongoing research and data analysis, in situ 
measurements of sound sources' . . . .'' Multiple commenters suggested 
that monitoring plans should be designed and coordinated across 
surveys. Commenters also noted that there are many research gaps that 
need to be filled, and suggested that NMFS should include monitoring 
requirements that fill those gaps--such as marine mammal habitat use, 
abundance surveys, masking, mysticete hearing ranges, behavioral 
response thresholds, ecosystem-wide impacts, and the efficacy of 
mitigation measures. Specific recommendations included acoustic 
receivers outside the survey area to allow for recording and assessment 
before, during, and after surveys, as well as aerial surveys to 
evaluate platform-based visual monitoring.
    Response: Section 101(a)(5)(D) of the MMPA indicates that any 
authorization NMFS issues shall include ``requirements pertaining to 
the monitoring and reporting of such taking by harassment.'' This broad 
requirement allows for a high degree of flexibility in what NMFS may 
accept or include as a monitoring requirement, but is not specific in 
identifying a threshold of what should be considered adequate 
monitoring. Contrary to NRDC's comments, except for IHAs in Arctic 
waters, NMFS's implementing regulations do not provide a specific 
standard regarding what required monitoring and reporting measures 
``must'' accomplish. However, they do direct that ``requests,'' i.e., 
the materials submitted by applicants, should include ``the suggested 
means of accomplishing the necessary monitoring and reporting that will 
result in increased knowledge of the species, the level of taking or 
impacts on populations of marine mammals that are expected to be 
present while conducting activities, and suggested means of minimizing 
burdens by coordinating such reporting requirements with other schemes 
already applicable to persons conducting such activity.'' NRDC further 
extracts pieces of this language to suggest that in the case of these 
five applicants, they are required to coordinate with each other's 
monitoring efforts, ignoring the fact that the regulation points to 
this coordination only in support of minimizing the burden on the 
applicant and that it refers to coordination with ``schemes already 
applicable to persons conducting such activity,'' of which there are 
currently none. NRDC attempts to further this argument that 
coordination across projects is required by statute by pointing to a 
compliance scheme that they state is in development for the Gulf of 
Mexico.
    However, as described elsewhere in this document, section 
101(a)(5)(D) of the MMPA indicates that the analysis, the findings, and 
any requirements included in the development of an IHA pertain only to 
the specified activity--specifically, NMFS is required to include the 
``requirements pertaining to the monitoring and reporting of such 
taking by harassment'' (referring to the taking authorized in the IHA). 
Notably, section 101(a)(5)(A), which applies in the case of NMFS's 
incidental take regulations for a specified activity for up to five 
years, contains similar requirements, but the requirements apply to the 
entirety of the activities covered under any incidental take 
rulemaking. Indeed, NMFS's implementing regulations indicate that ``for 
all petitions for regulations [ . . . ] applicants must provide the 
information requested in 216.104 on their activity as a whole.'' 
Therefore, it

[[Page 63314]]

is appropriate that a monitoring plan developed in support of BOEM's 
requested rulemaking to cover incidental take from activities covered 
by their oil and gas program in the Gulf of Mexico would address, and 
potentially coordinate across, multiple surveys.
    Although the statute provides flexibility in what constitutes 
acceptable monitoring and reporting measures (increased knowledge of 
the species and the taking), NMFS's implementing regulations provide 
additional guidance as to what an applicant should submit in their 
requests, indicating ``Monitoring plans should include a description of 
the techniques that would be used to determine the movement and 
activities of marine mammals near the activity site(s) including 
migration and habitat uses, such as feeding.'' We appreciate the 
recommendations provided by the public, and agree that from a content 
standpoint, many of the recommendations could qualify as appropriate 
monitoring for any of these surveys. However, we note that many of the 
monitoring recommendations require a scale of effort that is not 
commensurate to the scale of either the underlying activities or the 
anticipated impacts of the activities on marine mammals covered by any 
single IHA. In other words, many of the recommended measures would 
necessitate complex and expensive survey designs and methods that would 
exceed the duration of any one activity (e.g., regular distribution and 
abundance surveys, moored arrays for before/during/after studies) and/
or require levels of collaboration, planning and permitting (behavioral 
response studies, aerial programs to evaluate mitigation effectiveness) 
that are not reasonable in the context of an activity that consists of 
one mobile source moving across a large area and that will last less 
than a year and, further, is not appropriate in the context of the 
comparatively smaller scale of total surveys in the Atlantic at the 
current time.
    Most importantly, regardless of whether other monitoring plans 
would also suffice, we believe that the visual and acoustic monitoring 
required for each of these surveys meets the MMPA requirement for 
monitoring and reporting. NRDC implies that monitoring within 1 km of 
the vessel is not useful or adequate. First, the required monitoring is 
not limited to within a zone, as PSOs will record the required 
information at whatever distance they can accurately collect it--and 
past monitoring reports from similar platforms show useful data 
collected beyond 1 km. Further, even if the PSOs cannot always see, or 
acoustically monitor, the entire zone within which take is estimated to 
occur, the data collected will still be both qualitatively and 
quantitatively informative, as behaviors will be detectable within 
these distances and there are accepted methods for extrapolating 
sightings data to make inferences about larger areas. For these 
surveys, the PSOs will gather detailed information on the marine 
mammals both sighted and acoustically detected, their behaviors 
(different facets detectable visually and acoustically) and locations 
in relation to the sound source, and the operating status of any sound 
sources--allowing for a better understanding of both the impacted 
species as well as the taking itself.
    Comment: Multiple commenters provided various comments concerning 
transparency and data sharing with regard to data reported to NMFS.
    Response: We agree with the overall point and will make all data 
reported to NMFS in accordance with IHA requirements available for 
public review following review and approval of reports by NMFS. 
However, several commenters were apparently confused about the nature 
of data required to be reported to NMFS and/or the mechanism of 
reporting. For example, Oceana stated that NMFS should ``make the 
seismic survey data available to industry, government, and the public 
so that all stakeholders can make an informed cost-benefit analysis and 
decide whether offshore drilling should be allowed. . . .'' However, 
the survey data apparently referenced by Oceana is not required to be 
provided by the applicants to NMFS, but is provided to BOEM. Oceana 
also stated that NMFS should ``live stream data as often as possible as 
well as archive the passive acoustic monitoring feed.'' Respectfully, 
we are unclear as to what Oceana is referring to.
    Comment: Several industry commenters took issue with the 15-km 
buffers that NMFS understands will be required around National Marine 
Sanctuaries.
    Response: We described these requirements, which are a product of 
discussions between BOEM and NOAA's Office of National Marine 
Sanctuaries, in our Notice of Proposed IHAs solely for purposes of 
thoroughness. Here, we clarify that this standoff distance is not a 
requirement of NMFS and will not be included in any issued IHAs. As 
such, criticisms of this requirement (which we expect to be included as 
conditions in permits issued by BOEM) are not relevant here and we do 
not respond to them.
    Comment: A few commenters suggested that NMFS should fully 
implement NOAA's Ocean Noise Strategy, which they interpreted as 
meaning that certain knowledge gaps on marine mammals and noise must be 
filled before NMFS may issue these IHAs. Another commenter said that to 
help support implementation of the Ocean Noise Strategy Roadmap 
(cetsound.noaa.gov/Assets/cetsound/documents/Roadmap/ONS_Roadmap_Final_Complete.pdf), the agencies (i.e., NOAA and BOEM) 
should undertake efforts to evaluate impacts to marine mammal habitat 
before, during, and after surveys occur.
    Response: NMFS appreciates the support for the Ocean Noise Strategy 
and agrees with the goal of focusing both agency science and agency-
required monitoring towards filling known gaps in our understanding of 
the effects of noise on marine mammals wherever possible and 
appropriate. The Ocean Noise Strategy does not mandate any specific 
actions, though; rather, it directs NOAA to use our existing 
authorities and capacities to focus on the management, science, 
decision-making tool, and outreach goals outlined in the Roadmap. In 
the case of MMPA incidental take authorizations, NMFS must abide by 
statutory directive, and we have described above (both in comment 
response and elsewhere in the body of this Notice) our rationale for 
including the monitoring and reporting measures in these IHAs. In the 
context of MMPA authorizations, it is typically easier to apply some of 
the monitoring and research goals articulated in the Ocean Noise 
Strategy through section 101(a)(5)(A) rulemaking, as the expanded scope 
and longer duration of the coverage period are better suited to more 
complex, large-scale, or expensive approaches (e.g., such as those 
utilized for U.S. Navy training and testing incidental take 
regulations).

National Environmental Policy Act

    Comment: NRDC and Oceana provide a litany of complaints regarding 
the sufficiency of BOEM's EIS and its suitability for supporting NMFS's 
decision analysis, and state that NMFS must prepare a separate analysis 
before taking action.
    Response: Following independent evaluation of BOEM's EIS, and 
review of public comments, NMFS determined BOEM's 2014 Final PEIS to be 
comprehensive in analyzing the broad scope of potential survey 
activities, and that the evaluation of the direct, indirect, and 
cumulative impacts on the human environment, including the marine 
environment, is adequate to

[[Page 63315]]

support NMFS's consideration for future issuance of ITAs to geophysical 
companies and other potential applicants through tiering and 
incorporation by reference. NMFS further determined that subsequent 
issuance of ITAs for survey activities is likely to fall within the 
scope of the analysis in the 2014 Final PEIS, particularly since the 
impacts of the alternatives evaluated by BOEM (1) assess impact over a 
much longer period of time (i.e., nine years) than is analyzed by NMFS 
for any given ITA, (2) encompass many of the same factors NMFS 
historically considered when reviewing ITAs for geophysical surveys or 
related activity (i.e., marine mammal exposures, intensity of acoustic 
exposure, monitoring and mitigation factors, and more), and (3) are 
substantially the same as the impacts of NMFS's issuance of any given 
ITA for take of marine mammals incidental to future applicants' survey 
activities. The 2014 Final PEIS also addresses NOAA's required 
components for adoption as it meets the requirements for an adequate 
EIS under the CEQ regulations (40 CFR part 1500-1508) and NOAA 
Administrative Order 216-6A and reflects comments and expert input 
provided by NOAA as a cooperating agency. Therefore, NMFS subsequently 
signed a Record of Decision that: (1) Adopted the Final PEIS to support 
NMFS's analysis associated with issuance of ITAs pursuant to sections 
101(a)(5)(A) or (D) of the MMPA and the regulations governing the 
taking and importing of marine mammals (50 CFR part 216), and (2) in 
accordance with 40 CFR 1505.2, announced and explained the basis for 
NMFS's decision to review and potentially issue ITAs under the MMPA on 
a case-by-case basis, if appropriate, guided by the analyses in the 
Final PEIS and mitigation measures specified in BOEM's 2014 ROD.
    However, following review of public comments, NMFS agrees with NRDC 
and other commenters who suggested that it would not be appropriate for 
NMFS to simply adopt BOEM's EIS (our stated approach in the Notice of 
Proposed IHAs). Although we disagree with claims that the EIS is 
deficient, it is appropriate to evaluate whether supplementation is 
necessary. In so doing, we consider (1) whether new information not 
previously considered in the EIS is now available; (2) whether that new 
information may change the impact analysis contained in the EIS; and 
(3) whether our impact conclusions may change as a result of the new 
information and new impact analyses. However, we further consider that 
the EIS was purposely developed so that additional information could be 
included in subsequent NEPA evaluations. Because we determined that 
relevant new information was in fact available, in addition to 
applicant-specific details, we determined it appropriate to conduct a 
supplemental Environmental Assessment.
    NMFS determined that conducting NEPA review and preparing a tiered 
EA is appropriate to analyze environmental impacts associated with 
NMFS's issuance of separate IHAs to five different companies. NMFS 
further determined that the issuance of these five IHAs are ``similar'' 
but not ``connected actions'' per 40 CFR 1508.25(a)(3) due to general 
commonalities in geography, timing, and type of activity, which 
provides a reasonable basis for evaluating them together in a single 
environmental analysis. The EA also incorporates relevant portions of 
BOEM's Final PEIS while focusing analysis on environmental issues 
specific to the five IHAs. NMFS has completed the necessary 
environmental analysis under NEPA.

Miscellaneous

    Comment: Several commenters suggest that NMFS should require the 
applicants to consolidate their surveys.
    Response: Requiring individual applicants to alter their survey 
objectives and/or design does not fall within NMFS's authority. 
Moreover, though these multiple concurrent surveys are perceived as 
``duplicative,'' they are in fact designed specifically to produce 
proprietary data that satisfies the needs of survey funders. As is the 
current practice in the Gulf of Mexico, it is within BOEM's 
jurisdiction as the permitting agency to require permit applicants to 
submit statements indicating that existing data are not available to 
meet the data needs identified for the applicant's survey (i.e., non-
duplicative survey statement), but such requirements are not within 
NMFS's purview. For example, NRDC claims erroneously that NMFS ``has 
authority under the mitigation provision of the MMPA to consider 
directing the companies to consolidate their surveys,'' placing such a 
requirement under the auspices of practicability. Leaving aside that 
directing any given applicant to abandon their survey plans would not 
in fact be practicable, it is inappropriate to consider this suggested 
requirement through that lens. Similarly, the MMC vaguely references 
section 101(a)(5)(A)(i)(II)(aa) in stating that NMFS is provided 
authority to require such consolidation--we assume that MMC intended to 
reference the parallel language at section 101(a)(5)(D)(ii)(I), which 
states only that NMFS shall prescribe the ``means of effecting the 
least practicable impact on such species or stock and its habitat.'' 
NMFS considers the specified activity described by an applicant in 
reviewing a request for an incidental take authorization; nothing in 
the statute provides authority to direct consolidation of independent 
specified activities (regardless of any presumption of duplication, 
about which NMFS is not qualified to judge).
    The MMC specifically cites a number of collaborative surveys 
conducted in foreign waters, and recommends that NMFS ``work with 
BOEM'' to require such collaboration. However, MMC provides no useful 
recommendations as to how such collaboration might be achieved. Given 
the absence of appropriate statutory authority, we recommend that the 
MMC itself undertake to foster such collaboration between geophysical 
data acquisition companies and relevant Federal agencies as it deems 
necessary to protect and conserve marine mammals. NMFS looks forward to 
joining in such an MMC-led collaboration, as appropriate.
    We also note that industry commenters stated, anticipating 
suggestions of this sort, that such recommendations ``are based upon a 
substantial misunderstanding of important technical, operational, and 
economic aspects of seismic surveying.'' These commenters also noted 
that, based on the findings of an expert panel recently convened by 
BOEM to study the issue of duplicative surveys (see Appendix L in BOEM, 
2017), none of the surveys considered here would meet the definition 
established for a ``duplicate'' survey.
    Comment: NRDC contends that NMFS must consider a standard requiring 
analysis and selection of minimum source levels. In furtherance of this 
overall quieting goal, NRDC also states that NMFS should consider 
requiring that all vessels employed in the survey activities undergo 
regular maintenance to minimize propeller cavitation and be required to 
employ the best ship-quieting designs and technologies available for 
their class of ship, and that we should require these vessels to 
undergo measurement for their underwater noise output.
    Response: An expert panel convened by BOEM to determine whether it 
would be feasible to develop standards to determine a lowest 
practicable source level has determined that it would not be reasonable 
or practicable to develop such metrics (see Appendix L in BOEM,

[[Page 63316]]

2017). We appreciate that NRDC disagrees with the panel's findings, but 
we do not believe it appropriate to address these grievances to NMFS. 
NRDC further claims that NMFS's deference to the findings of an expert 
panel convened specifically to consider this issue is ``arbitrary under 
the MMPA.'' The bulk of NRDC's comment appears to be addressed to BOEM, 
and we encourage NRDC to engage with BOEM regarding these supposed 
shortcomings of the panel's findings. The subject matter is outside 
NMFS's expertise, and we have no basis upon which to doubt the panel's 
published findings. We decline to address here the ways in which NRDC 
claims that BOEM misunderstood the issue.
    With regard to the recommended requirements to measure or control 
vessel noise, or to make some minimum requirements regarding the design 
of vessels used in the surveys, we disagree that these requirements 
would be practicable. While we agree that vessel noise is of concern in 
a cumulative and chronic sense, it is not of substantial concern in 
relation to the MMPA's least practicable adverse impact standard, given 
the few vessels used in any given specified activity. NMFS looks 
forward to continued collaboration with NRDC and others towards ship 
quieting.

Description of Marine Mammals in the Area of the Specified Activities

    We refer readers to NMFS's Stock Assessment Reports (SAR; 
www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments), species descriptions provided on NMFS's website 
(www.fisheries.noaa.gov/find-species), and to the applicants' species 
descriptions (Sections 3 and 4 of the applications). These sources 
summarize available information regarding physical descriptions, status 
and trends, distribution and habitat preferences, behavior and life 
history, and auditory capabilities of the potentially affected species, 
and are not reprinted here.
    Table 2 lists all species with expected potential for occurrence in 
the mid- and south Atlantic and summarizes information related to the 
population or stock, including potential biological removal (PBR). For 
taxonomy, we follow Committee on Taxonomy (2017). PBR, defined by the 
MMPA as the maximum number of animals, not including natural 
mortalities, that may be removed from a marine mammal stock while 
allowing that stock to reach or maintain its optimum sustainable 
population, is considered in concert with known sources of ongoing 
anthropogenic mortality (as described in NMFS's SARs). For status of 
species, we provide information regarding U.S. regulatory status under 
the MMPA and ESA.
    Marine mammal abundance estimates presented in this document 
represent the total number of individuals that make up a given stock or 
the total number estimated within a particular study area. NMFS's stock 
abundance estimates for most species represent the total estimate of 
individuals within the geographic area, if known, that comprises that 
stock. For some species, this geographic area may extend beyond U.S. 
waters. Survey abundance (as compared to stock or species abundance) is 
the total number of individuals estimated within the survey area, which 
may or may not align completely with a stock's geographic range as 
defined in the SARs. These surveys may also extend beyond U.S. waters.
    In some cases, species are treated as guilds. In general ecological 
terms, a guild is a group of species that have similar requirements and 
play a similar role within a community. However, for purposes of stock 
assessment or abundance prediction, certain species may be treated 
together as a guild because they are difficult to distinguish visually 
and many observations are ambiguous. For example, NMFS's Atlantic SARs 
assess Mesoplodon spp. and Kogia spp. as guilds. Here, we consider 
pilot whales, beaked whales (excluding the northern bottlenose whale), 
and Kogia spp. as guilds. In the following discussion, reference to 
``pilot whales'' includes both the long-finned and short-finned pilot 
whale, reference to ``beaked whales'' includes the Cuvier's, 
Blainville's, Gervais, Sowerby's, and True's beaked whales, and 
reference to ``Kogia spp.'' includes both the dwarf and pygmy sperm 
whale.
    Thirty-four species (with 39 managed stocks) are considered to have 
the potential to co-occur with the planned survey activities. Species 
that could potentially occur in the survey areas but are not expected 
to have reasonable potential to be harassed by any survey are omitted 
from further analysis. These include extralimital species, which are 
species that do not normally occur in a given area but for which there 
are one or more occurrence records that are considered beyond the 
normal range of the species. Extralimital species or stocks unlikely to 
co-occur with survey activity include nine estuarine bottlenose dolphin 
stocks, four pinniped species, the white-beaked dolphin (Lagenorhynchus 
albirostris), and the beluga whale (Delphinapterus leucas). For 
detailed discussion of these species, please see our Federal Register 
Notice of Proposed IHAs (82 FR 26244; June 6, 2017). In addition, the 
West Indian manatee (Trichechus manatus latirostris) may be found in 
coastal waters of the Atlantic. However, manatees are managed by the 
U.S. Fish and Wildlife Service and are not considered further in this 
document. All managed stocks in this region are assessed in NMFS's U.S. 
Atlantic SARs. All values presented in Table 2 are the most recent 
available at the time of publication and are available in the 2017 SARs 
(Hayes et al., 2018a) and draft 2018 SARs (available online at: 
www.fisheries.noaa.gov/national/marine-mammal-protection/draft-marine-mammal-stock-assessment-reports).

                                    Table 2--Marine Mammals Potentially Present in the Vicinity of Survey Activities
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                         NMFS stock
                                                                         ESA/ MMPA     abundance (CV,     Predicted mean   Predicted            Annual M/
          Common name             Scientific name         Stock           status;    Nmin, most recent     (CV)/maximum    abundance     PBR     SI (CV)
                                                                       strategic (Y/ abundance survey)    abundance \3\     outside                \5\
                                                                          N) \1\            \2\                             EEZ \4\
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                          Order Cetartiodactyla--Cetacea--Superfamily Mysticeti (baleen whales)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Balaenidae:
    North Atlantic right whale.  Eubalaena          Western North      E/D; Y        451 (n/a; 445; n/  394 (0.07) *.....          1       0.9      5.56
                                  glacialis.         Atlantic (WNA).                  a).
Family Balaenopteridae
 (rorquals):
    Humpback whale.............  Megaptera          Gulf of Maine....  -; N          896 (n/a; 896;     1,637 (0.07) */            8      14.6       9.8
                                  novaeangliae                                        2015).             1,994.
                                  novaeangliae.

[[Page 63317]]

 
    Minke whale................  Balaenoptera       Canadian East      -; N          2,591 (0.81;       2,112 (0.05) */          929        14       7.5
                                  acutorostrata      Coast.                           1,425; 2011).      2,431.
                                  acutorostrata.
    Bryde's whale..............  B. edeni brydei..  None defined \6\.  -; n/a        n/a..............  7 (0.58)/n/a.....          7       n/a       n/a
    Sei whale..................  B. borealis        Nova Scotia......  E/D; Y        357 (0.52; 236;    717 (0.30) */             46       0.5       0.6
                                  borealis.                                           2011).             1,519.
    Fin whale..................  B. physalus        WNA..............  E/D; Y        1,618 (0.33;       4,633 (0.08)/             44       2.5       2.5
                                  physalus.                                           1,234; 2011).      6,538.
    Blue whale.................  B. musculus        WNA..............  E/D; Y        Unknown (n/a;      11 (0.41)/n/a....          4       0.9      Unk.
                                  musculus.                                           440; n/a).
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                            Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Physeteridae:
    Sperm whale................  Physeter           North Atlantic...  E/D; Y        2,288 (0.28;       5,353 (0.12)/          2,456       3.6       0.8
                                  macrocephalus.                                      1,815; 2011).      7,193.
Family Kogiidae:
    Pygmy sperm whale..........  Kogia breviceps..  WNA..............  -; N          3,785 (0.47;       678 (0.23)/n/a           428        21       3.5
                                                                                      2,598; 2011) \7\.  \7\.                                      (1.0)
    Dwarf sperm whale..........  K. sima..........  WNA..............  -; N
Family Ziphiidae (beaked
 whales):
    Cuvier's beaked whale......  Ziphius            WNA..............  -; N          6,532 (0.32;       14,491 (0.17)/         9,426        50       0.4
                                  cavirostris.                                        5,021; 2011).      16,635 \7\.
    Gervais beaked whale.......  Mesoplodon         WNA..............  -; N          7,092 (0.54;                                           46       0.2
                                  europaeus.                                          4,632; 2011) \7\.
    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)/n/a....         11    Undet.         0
                                  ampullatus.
Family Delphinidae:
    Rough-toothed dolphin......  Steno bredanensis  WNA..............  -; N          136 (1.0; 67;      532 (0.36)/n/a...        313       0.7         0
                                                                                      2016).
    Common bottlenose dolphin..  Tursiops           WNA Offshore.....  -; N          77,532 (0.40;      97,476 (0.06)/         5,280       561      39.4
                                  truncatus         WNA Coastal,       D; Y           56,053; 2011).     144,505 \7\.                       48    (0.29)
                                  truncatus.         Northern                        6,639 (0.41;                                                    6.1
                                                     Migratory.                       4,759;.                                                   (0.32)-1
                                                                                     2016)............                                               3.2
                                                                                                                                                  (0.22)
                                                    WNA Coastal,       D; Y          3,751 (0.60;                                           23    0-14.3
                                                     Southern          D; Y           2,353; 2016).                                         46    (0.31)
                                                     Migratory.                      6,027 (0.34;                                                1.4-1.6
                                                    WNA Coastal,                      4,569; 2016).
                                                     South Carolina/
                                                     Georgia.
                                                    WNA Coastal,       D; Y          877 (0.49; 595;                                         6       0.6
                                                     Northern Florida. D; Y           2016).                                               9.1       0.4
                                                    WNA Coastal,                     1,218 (0.35; 913;
                                                     Central Florida.                 2016).
    Clymene dolphin............  Stenella clymene.  WNA..............  -; N          6,086 (0.93;       12,515 (0.56)/n/a     11,503    Undet.         0
                                                                                      3,132; 1998) \8\.
    Atlantic spotted dolphin...  S. frontalis.....  WNA..............  -; N          44,715 (0.43;      55,436 (0.32)/         7,339       316         0
                                                                                      31,610; 2011).     137,795.
    Pantropical spotted dolphin  S. attenuata       WNA..............  -; N          3,333 (0.91;       4,436 (0.33)/n/a.      2,781        17         0
                                  attenuata.                                          1,733; 2011).
    Spinner dolphin............  S. longirostris    WNA..............  -; N          Unknown..........  262 (0.93)/n/a...        184    Undet.         0
                                  longirostris.
    Striped dolphin............  S. coeruleoalba..  WNA..............  -; N          54,807 (0.3;       75,657 (0.21)/        15,166       428         0
                                                                                      42,804; 2011).     172,158.
    Common dolphin.............  Delphinus delphis  WNA..............  -; N          70,184 (0.28;      86,098 (0.12)/         3,154       557       406
                                  delphis.                                            55,690; 2011).     129,977.                                 (0.10)
    Fraser's dolphin...........  Lagenodelphis      WNA..............  -; N          Unknown..........  492 (0.76)/n/a...        474    Undet.         0
                                  hosei.
    Atlantic white-sided         Lagenorhynchus     WNA..............  -; N          48,819 (0.61;      37,180 (0.07)/           368       304        57
     dolphin.                     acutus.                                             30,403; 2011).     59,008.                                  (0.15)
    Risso's dolphin............  Grampus griseus..  WNA..............  -; N          18,250 (0.46;      7,732 (0.09)/          1,060       126      49.9
                                                                                      12,619; 2011).     18,377.                                  (0.24)
    Melon-headed whale.........  Peponocephala      WNA..............  -; N          Unknown..........  1,175 (0.50)/n/a.      1,095    Undet.         0
                                  electra.
    Pygmy killer whale.........  Feresa attenuata.  WNA..............  -; N          Unknown..........  n/a..............        n/a    Undet.         0
    False killer whale.........  Pseudorca          WNA..............  -; Y          442 (1.06; 212;    95 (0.84)/n/a....         35       2.1      Unk.
                                  crassidens.                                         2011).
    Killer whale...............  Orcinus orca.....  WNA..............  -; N          Unknown..........  11 (0.82)/n/a....          4    Undet.         0
    Short-finned pilot whale...  Globicephala       WNA..............  -; N          28,924 (0.24;      18,977 (0.11)/         2,258       236       168
                                  macrorhynchus.                                      23,637; 2016).     35,715 \6\.                              (0.13)
Long-finned pilot whale........  G. melas melas...  WNA..............  -; N          5,636 (0.63;                                           35        27
                                                                                      3,464; 2011).                                               (0.18)

[[Page 63318]]

 
Family Phocoenidae (porpoises):
    Harbor porpoise............  Phocoena phocoena  Gulf of Maine/Bay  -; N          79,833 (0.32;      45,089 (0.12) */          91       706       255
                                  phocoena.          of Fundy.                        61,415; 2011).     50,315.                                  (0.18)
--------------------------------------------------------------------------------------------------------------------------------------------------------
\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.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments. CV
  is coefficient of variation; Nmin is the minimum estimate of stock abundance. In some cases, CV is not applicable. For the right whale, the best
  abundance value is based on a model of the sighting histories of individually identifiable animals (as of October 2017). The model of these histories
  produced a median abundance value of 451 whales (95 percent credible intervals 434-464). The minimum estimate of 440 blue whales represents
  recognizable photo-identified individuals.
\3\ This information represents species- or guild-specific abundance predicted by habitat-based cetacean density models (Roberts et al., 2016). For the
  North Atlantic right whale, we report the outputs of a more recently updated model (Roberts et al., 2017). These models provide the best available
  scientific information regarding predicted density patterns of cetaceans in the U.S. Atlantic Ocean, and we provide the corresponding mean annual and
  maximum monthly abundance predictions. Total abundance estimates were produced by computing the mean density of all pixels in the modeled area and
  multiplying by its area. Roberts et al. (2016) did not produce a density model for pygmy killer whales off the east coast. For those species marked
  with an asterisk, the available information supported development of either two or four seasonal models; each model has an associated abundance
  prediction. Here, we report the maximum predicted seasonal abundance.
\4\ The density models used to predict acoustic exposures (e.g., Roberts et al., 2016) provide abundance predictions for the area within the U.S. EEZ.
  However, the model outputs were also extrapolated to the portion of the specific geographic region outside the EEZ in order to predict acoustic
  exposures in that area (i.e., from 200 nmi to 350 nmi offshore). Therefore, we calculated corresponding seasonal abundance estimates for this region.
  The maximum seasonal abundance estimate is reported.
\5\ These values, found in NMFS's 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.
\6\ 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 that
  is resident in the northern Gulf of Mexico, but does not define a separate stock in the Atlantic Ocean.
\7\ Abundance estimates are in some cases reported for a guild or group of species when those species are difficult to differentiate at sea. Similarly,
  the habitat-based cetacean density models produced by Roberts et al. (2016) are based in part on available observational data which, in some cases, is
  limited to genus or guild in terms of taxonomic definition. NMFS's SARs present pooled abundance estimates for Kogia spp. and Mesoplodon spp., while
  Roberts et al. (2016) produced density models to genus level for Kogia spp. and Globicephala spp. and as a guild for most beaked whales (Ziphius
  cavirostris and Mesoplodon spp.). Finally, Roberts et al. (2016) produced a density model for bottlenose dolphins that does not differentiate between
  offshore and coastal stocks.
\8\ NMFS's abundance estimates for the Clymene dolphin is greater than eight years old and not considered current. PBR is therefore considered
  undetermined for this stock, as there is no current minimum abundance estimate for use in calculation. We nevertheless present the most recent
  abundance estimate.

    For the majority of species potentially present in the specific 
geographic region, NMFS has designated only a single generic stock 
(e.g., ``western North Atlantic'') for management purposes. This 
includes the ``Canadian east coast'' stock of minke whales, which 
includes all minke whales found in U.S. waters. For the humpback and 
sei whales, NMFS defines stocks on the basis of feeding locations, 
i.e., Gulf of Maine and Nova Scotia, respectively. However, our 
reference to humpback whales and sei whales in this document refers to 
any individuals of the species that are found in the specific 
geographic region. These individuals may be from the same breeding 
population (e.g., West Indies breeding population of humpback whales) 
but visit different feeding areas. For the bottlenose dolphin, NMFS 
defines an oceanic stock and multiple coastal stocks.
    North Atlantic Right Whale--We provide additional discussion of the 
North Atlantic right whale in order to address the current status of 
the species, which has deteriorated since publication of our Notice of 
Proposed IHAs. The North Atlantic right whale was severely depleted by 
historical whaling, and was originally listed as endangered under the 
ESA in 1970. The right whale's range historically extended to the 
eastern North Atlantic, as well as the Denmark Strait and waters south 
of Greenland. However, sightings of right whales beyond their current 
western North Atlantic distribution are rare and the eastern North 
Atlantic population may be functionally extinct (Kraus and Rolland, 
2007; Best et al., 2001). In the western North Atlantic, a median 
abundance value of 451 whales in October 2017 (as reported in NMFS's 
draft 2018 SARs and Table 2) based on a Bayesian mark-recapture open 
population model, which accounts for individual differences in the 
probability of being photographed (95 percent credible intervals 434-
464, Pace et al., 2017). Accurate pre-exploitation abundance estimates 
are not available for either population of the species. The western 
population may have numbered fewer than 100 individuals by 1935, when 
international protection for right whales came into effect (Kenney et 
al., 1995).
    Modeling suggests that in 1980, females had a life expectancy of 
approximately 52 years of age (twice that of males at the time) 
(Fujiwara and Caswell, 2001). However, due to reduced survival 
probability, in 1995 female life expectancy was estimated to have 
declined to approximately 15 years, with males having a slightly higher 
life expectancy into the 20s (Fujiwara and Caswell, 2001). A recent 
study demonstrated that females have substantially higher mortality 
than males (Pace et al., 2017), and as a result, also have 
substantially shorter life expectancies.
    Gestation is approximately one year, after which calves typically 
nurse for around a year (Kenney, 2009; Kraus et al., 2007; Lockyer, 
1984). After weaning calves, females typically undergo a `resting' year 
before becoming pregnant again, presumably because they need time to 
recover from the energy deficit experienced during lactation (Fortune 
et al., 2012, 2013; Pettis et al., 2017b). From 1983 to 2005, annual 
average calving intervals ranged from 3 to 5.8 years (Knowlton et al., 
1994; Kraus et al., 2007). Between 2006 and 2015, annual average 
calving intervals continued to vary within this range, but in 2016 and 
2017 longer calving intervals were reported (6.3 to 6.6 years in 2016 
and 10.2 years in 2017; Pettis and Hamilton, 2015, 2016; Pettis et al., 
2017a; Surrey-Marsden et al., 2017; Hayes et al., 2018b). Females have 
been known to give birth as young as five years old, but the mean age 
of first parturition is about 10 years old (Kraus et al., 2007).

[[Page 63319]]

    Pregnant North Atlantic right whales migrate south, through the 
mid-Atlantic region of the United States, to low latitudes during late 
fall where they overwinter and give birth in shallow, coastal waters 
(Kenney, 2009; Krzystan et al., 2018). During spring, these females 
migrate back north with their new calves to high latitude foraging 
grounds where they feed on large concentrations of copepods, primarily 
Calanus finmarchicus (NMFS, 2017). Some non-reproductive North Atlantic 
right whales (males, juveniles, non-reproducing females) also migrate 
south through the mid-Atlantic region, although at more variable times 
throughout the winter, while others appear to not migrate south, and 
instead remain in the northern feeding grounds year round or go 
elsewhere (Bort et al., 2015; Morano et al., 2012; NMFS, 2017). 
Nonetheless, calving females arrive to the southern calving grounds 
earlier and stay in the area more than twice as long as other 
demographics (Krzystan et al., 2018). Little is known about North 
Atlantic right whale habitat use in the mid-Atlantic, but recent 
acoustic data indicate near year-round presence of at least some whales 
off the coasts of New Jersey, Virginia, and North Carolina (Davis et 
al., 2017; Hodge et al., 2015a; Salisbury et al., 2016; Whitt et al., 
2013). Oedekoven et al. (2015) conducted an expert elicitation exercise 
to assess potential seasonal abundance of right whales in the mid-
Atlantic, confirming that very low numbers of whales should be expected 
to be present in the region outside of the November to April timeframe. 
While it is generally not known where North Atlantic right whales mate, 
some evidence suggests that mating may occur in the northern feeding 
grounds (Cole et al., 2013; Matthews et al., 2014).
    The western North Atlantic right whale population demonstrated 
overall growth of 2.8 percent per year between 1990 to 2010, despite a 
decline in 1993 and no growth between 1997 and 2000 (Pace et al., 
2017). However, since 2010 the population has been in decline, with a 
99.99 percent probability of a decline of just under one percent per 
year (Pace et al., 2017). Between 1990 and 2015, survival rates 
appeared to be relatively stable, but differed between the sexes, with 
males having higher survivorship than females (males: 0.985  0.0038; females: 0.968  0.0073) leading to a male-
biased sex ratio (approximately 1.46 males per female; Pace et al., 
2017). During this same period, calving rates varied substantially, 
with low calving rates coinciding with all three periods of decline or 
no growth (Pace et al., 2017). On average, North Atlantic right whale 
calving rates are estimated to be roughly half that of southern right 
whales (E. australis) (Pace et al., 2017), which are increasing in 
abundance (NMFS, 2015c).
    While data are not yet available to statistically estimate the 
population's trend beyond 2015, three lines of evidence indicate the 
population is still in decline. First, calving rates in recent years 
were low, with only five new calves being documented in 2017 (Pettis et 
al., 2017a), well below the number needed to compensate for expected 
mortalities (Pace et al., 2017). In 2018, no new North Atlantic right 
whale calves were documented in their calving grounds; this represented 
the first time since annual NOAA aerial surveys began in 1989 that no 
new right whale calves were observed. Long-term photographic 
identification data indicate new calves rarely go undetected, so these 
years likely represent a continuation of the low calving rates that 
began in 2012 (Kraus et al., 2007; Pace et al., 2017). Second, as noted 
above, the abundance estimate for 2016 is 451 individuals, down 
approximately 1.5 percent from 458 in 2015. Third, since June 2017, at 
least 20 North Atlantic right whales have died in what has been 
declared an Unusual Mortality Event (UME; see additional discussion of 
the UME below).
    Analysis of mtDNA from North Atlantic right whales has identified 
seven mtDNA haplotypes in the western North Atlantic (Malik et al., 
1999; McLeod and White, 2010). This is significantly less diverse than 
southern right whales and may indicate inbreeding (Hayes et al., 2018a; 
Malik et al., 2000; Schaeff et al., 1997). While analysis of historic 
DNA taken from museum specimens indicates that the eastern and western 
populations were likely not genetically distinct, the lack of recovery 
of the eastern North Atlantic population indicates at least some level 
of population segregation (Rosenbaum et al., 1997, 2000). Overall, the 
species has low genetic diversity as would be expected based on its low 
abundance. However, analysis of 16th and 17th century whaling bones 
indicate this low genetic diversity may pre-date whaling activities 
(McLeod et al., 2010). Despite this, Frasier et al. (2013) recently 
identified a post-copulatory mechanism that appears to be slowly 
increasing genetic diversity among right whale calves.
    In recent years, there has been a shift in distribution in right 
whale feeding grounds, with fewer animals being seen in the Great South 
Channel and the Bay of Fundy and perhaps more animals being observed in 
the Gulf of Saint Lawrence and mid-Atlantic region (Daoust et al., 
2017; Davis et al., 2017; Hayes et al., 2018a; Pace et al., 2017; 
Meyer-Gutbrod et al., 2018). However, in recent years, a few known 
individuals from the western population have been seen in the eastern 
Atlantic, suggesting some individuals may have wider ranges than 
previously thought (Kenney, 2009).
    Currently, no identified right whale recovery goals have been met 
(for more information on these goals, see the 2005 recovery plan; NMFS, 
2005, 2017). With whaling now prohibited, the two major known human 
causes of mortality are vessel strikes and entanglement in fishing gear 
(Hayes et al., 2018b). Some progress has been made in mitigating vessel 
strikes by regulating vessel speeds in certain areas (78 FR 73726; 
December 9, 2013) (Conn and Silber, 2013), but entanglement in fishing 
gear remains a major threat (Kraus et al., 2016), which appears to be 
worsening (Hayes et al., 2018b). From 1990 to 2010, the population 
experienced overall growth consistent with one of its recovery goals. 
However, the population is currently experiencing a UME that appears to 
be related to both vessel strikes and entanglement in fishing gear 
(Daoust et al., 2017; see below for further discussion). In addition, 
the low female survival, male biased sex ratio, and low calving success 
indicated by recent modeling are contributing to the population's 
current decline (Pace et al., 2017). While there are likely a multitude 
of factors involved, low calving has been linked to poor female health 
(Rolland et al., 2016) and reduced prey availability (Meyer-Gutbrod and 
Greene, 2014, 2017; Meyer-Gutbrod et al., 2018). Furthermore, 
entanglement in fishing gear appears to have substantial health and 
energetic costs that affect both survival and reproduction (Pettis et 
al., 2017b; Robbins et al., 2015; Rolland et al., 2017; van der Hoop et 
al., 2017; Hayes et al., 2018b; Hunt et al., 2018; Lysiak et al., 
2018). In fact, there is evidence of a population-wide decline in 
health since the early 1990s, the last time the population experienced 
a population decline (Rolland et al., 2016). Given this status, the 
species resilience to future perturbations is considered very low 
(Hayes et al., 2018b). Using a matrix population projection model, 
Hayes et al. (2018b) estimate that by 2029 the population will to 
decline to the 1990 estimate of 123 females if the current rate of 
decline is not altered. Consistent with this, recent modelling efforts 
by Meyer-Gutbrod and Greene (2017) indicate that that the species may 
decline towards

[[Page 63320]]

extinction if prey conditions worsen, as predicted under future climate 
scenarios, and anthropogenic mortalities are not reduced (Grieve et 
al., 2017; Meyer-Gutbrod et al., 2018). In fact, recent data from the 
Gulf of Maine and Gulf of St. Lawrence indicate prey densities may 
already be in decline (Devine et al., 2017; Johnson et al., 2013; 
Meyer-Gutbrod et al., 2018).
    Discussion of Abundance Estimates--In Table 2 above, we report two 
sets of abundance estimates: Those from NMFS's SARs and those predicted 
by Roberts et al. (2016)--for the latter we provide both the annual 
mean and maximum, for those taxa for which monthly predictions are 
available (i.e., all taxa for which density surface models, versus 
stratified models, were produced). Please see Table 2, footnotes 2-3 
for more detail. We provided a relatively brief discussion of available 
abundance estimates in the Notice of Proposed IHAs, stating that the 
Roberts et al. (2016) abundance predictions are generally the most 
appropriate in this case for purposes of comparison with estimated 
exposures (see ``Estimated Take''). This is because the outputs of 
these models were used in most cases to generate the exposure 
estimates, i.e., we appropriately make relative comparisons between the 
exposures predicted by the outputs of the model and the abundance 
predicted by the model. Following review of public comments received 
and additional review of available information regarding abundance 
estimates, we provide revised and additional discussion of available 
abundance estimates and our use of these herein.
    Because both the SAR (in most cases) and Roberts et al. (2016) 
values provide estimates of abundance only within the U.S. EEZ, whereas 
the specified activities (and associated exposure estimates) extend 
beyond this region out to 350 nmi, we calculated the expected abundance 
of each species in the region offshore of the EEZ out to 350 nmi. These 
values, reported in Table 2, are appropriately added to the Roberts et 
al. (2016) EEZ estimates to provide the total model-predicted 
abundance. Please see footnote 4 for more detail. Our prior use of 
abundance estimates that ignore the assumed abundance of animals 
outside the EEZ (explicit in the exposure estimation process) was an 
error that is rectified here.
    As was described in our Notice of Proposed IHAs, NMFS's SAR 
abundance estimates are typically generated from the most recent 
shipboard and/or aerial surveys conducted, and often incorporate 
correction for detection bias. While these snapshot estimates provide 
valuable information about a stock, they are not generally relevant 
here for use in comparison to the take estimates, as stated above. The 
Roberts et al. (2016) abundance estimates represent the output of 
predictive models derived from observations and associated 
environmental parameters and are in fact based on substantially more 
data than are NMFS's SAR abundance estimates--thus minimizing the 
influence of interannual variability on abundance estimates. For 
example, NMFS's pilot whale abundance estimates from surveys conducted 
in 2004 and 2011 differed by 21 percent--a change not expected to 
represent the actual change in abundance--indicating that it may be 
more appropriate to use a model prediction that incorporates all 
available data.
    The abundance values reported by Roberts et al. (2016), and which 
we largely used in our analyses in the Notice of Proposed IHAs, are 
mean annual abundance estimates (for species for which data are 
sufficient to model seasonality; for other species only a stratified 
model with static abundance could be produced). However, for those 
species for which seasonal variability could be modeled (via density 
surface models), abundance estimates are produced for each month 
(monthly maps of species distribution and associated abundance values 
are provided in supplementary reports for each taxon; these are 
available online at: seamap.env.duke.edu/models/Duke-EC-GOM-2015/). 
Following review of public comments received, we determined it 
appropriate to use the most appropriate maximum abundance estimate for 
purposes of comparison with the exposure estimate, rather than the 
mean. While it is appropriate to use a mean density value in estimating 
potential exposures over a year in order to avoid over- or under-
estimation, the best actual population estimate for comparison would be 
the maximum theoretical population. That is, exposure estimates are 
most appropriately generated through use of means precisely because 
densities are expected to fluctuate within a study area throughout the 
year; however, because these fluctuations do not represent actual 
changes in population size, the maximum predicted abundance should be 
used in comparison with a given exposure estimate.
    The appropriate maximum estimate for each taxon more closely 
represents actual total theoretical abundance of the stock as a whole, 
as those animals may exit the study area during other months but still 
exist conceptually as members of the population. The mean does not 
represent the actual population abundance, because although there are 
seasonal shifts in distribution, the actual population abundance should 
be as estimated for the period when the largest portion of the 
population is present in the area. While species may migrate or shift 
distribution out of the study area, total abundance of a stock changes 
only via births and deaths, i.e., there is only one true abundance of 
the species. We note that for some taxa, Roberts et al. express 
confidence in the monthly model outputs, e.g., where the predicted 
seasonal variations in abundance match those reported in the 
literature. However, for others they do not, e.g., where there is 
little information available in the literature to corroborate the 
predicted seasonal variation. Lack of corroboration in the latter 
example would be a valid reason for not relying on monthly model 
outputs when determining the timing or location of a specific project. 
However, this does not impact our determination that the maximum 
theoretical population abundance is appropriate to use for purposes of 
comparison. For those taxa for which the monthly predictions are 
recommended for use, we use the maximum monthly prediction. For the 
remaining taxa for which a density surface model could be produced, we 
believe that use of the maximum monthly prediction may also be 
warranted. However, because for some of these species there are 
substantial month-to-month fluctuations and a corresponding lack of 
data in the literature regarding seasonal distribution, we use the 
maximum mean seasonal (i.e., three-month) abundance prediction for 
purposes of comparison as a precaution.
    For most species, we use the Roberts et al. (2016) abundance 
estimate, but substitute the appropriate maximum estimate for the mean 
annual estimate. Where we deviate from this practice, e.g., because 
another available abundance estimate provides more complete coverage of 
the stock's range, we provide additional discussion below. We also note 
that, regarding SAR abundance estimates, Waring et al. (2015) state 
that the population of sperm whales found within the eastern U.S. 
Atlantic EEZ likely represent only a fraction of the total stock, 
indicating that the abundance associated with animals found in the 
EEZ--whether the SAR abundance or the model-predicted abundance--likely 
underestimate the true abundance of the relevant population. 
Additionally, the majority of current NMFS SAR estimates--those

[[Page 63321]]

based on 2011 NOAA survey effort--do not account for availability bias 
due to submerged animals, so these abundance estimates are likely 
biased low.
    NMFS's abundance estimate for the North Atlantic right whale is 
based on models of the sighting histories of individual whales 
identified using photo-identification techniques. North Atlantic right 
whales represent one of the most intensely studied populations of 
cetaceans in the world with effort supported by a rigorously maintained 
individual sightings database and considerable survey effort throughout 
their range; therefore, the most appropriate abundance estimate is 
based on this photo-identification database. The current estimate of 
451 individuals (95% credible intervals 434-464) reflects the database 
as of November 2017 (www.fisheries.noaa.gov/national/marine-mammal-protection/draft-marine-mammal-stock-assessment-reports).
    The 2007 Canadian Trans-North Atlantic Sighting Survey (TNASS), 
which provided full coverage of the Atlantic Canadian coast (Lawson and 
Gosselin, 2009), provided abundance estimates for multiple stocks. The 
abundance estimates from this survey were corrected for perception and 
availability bias, when possible. In general, where the TNASS survey 
effort provided superior coverage of a stock's range (as compared with 
NOAA survey effort), we elect to use the resulting abundance estimate 
over either the current NMFS abundance estimate (derived from survey 
effort with inferior coverage of the stock range) or the Roberts et al. 
(2016) predictions (which are based on survey data from within U.S. 
waters). The TNASS data were not made available to the model authors 
(Roberts et al., 2015a).
    We use the TNASS abundance estimate for the minke whale and for the 
short-beaked common dolphin. While the TNASS survey also produced an 
abundance estimate of 3,522 (CV=0.27) fin whales, and similarly better 
represents the stock range than does NMFS's SAR estimate, this value 
underrepresents the maximum population predicted by Roberts et al. 
(2016). We also note that, while there appears to be some slight 
overlap in their coverage of stock ranges, the abundance estimates 
provided by the TNASS surveys and by NMFS's SAR estimates largely cover 
separate portions of the ranges. The TNASS effort involved aerial 
surveys covering the Labrador Shelf and Grand Banks, the Gulf of St. 
Lawrence, and the Scotian Shelf, and the abundance estimates also 
included the results of aerial surveys conducted by NOAA in the Bay of 
Fundy. NMFS's current SAR estimates reflect NOAA shipboard and aerial 
survey effort conducted from Florida to the lower Bay of Fundy. 
Therefore, the most appropriate abundance estimate for these stocks may 
be a combination of the abundance estimates (for common dolphin: 70,184 
(SAR) + 173,486 (TNASS) = 243,670; for minke whale: 2,591 (SAR) + 
20,741 (TNASS) = 23,332). Other abundance estimates that may cover 
additional portions of these stocks' ranges are described in Waring et 
al. (2013). However, we use only the TNASS estimates, which better 
cover the stock ranges, because we are uncertain about the degree of 
potential coverage overlap in Canadian waters.
    Note that, while the same TNASS survey produced an abundance 
estimate of 2,612 (CV=0.26) humpback whales, the survey did not provide 
superior coverage of the stock's range in the same way that it did for 
minke whales (Waring et al., 2016; Lawson and Gosselin, 2011). In 
addition, based on photo-identification only 39 percent of individual 
humpback whales observed along the mid- and south Atlantic U.S. coast 
are from the Gulf of Maine stock (Barco et al., 2002). Therefore, we 
use the Roberts et al. (2016) prediction for humpback whales. We note 
that the Roberts et al. (2016) maximum estimate of 1,994 humpback 
whales likely underrepresents the relevant population, i.e., the West 
Indies breeding population. Bettridge et al. (2003) estimated the size 
of this population at 12,312 (95% CI 8,688-15,954) whales in 2004-05, 
which is consistent with previous population estimates of approximately 
10,000-11,000 whales (Stevick et al., 2003; Smith et al., 1999) and the 
increasing trend for the West Indies DPS (Bettridge et al., 2015). 
However, we retain the value predicted by Roberts et al. (2016) for 
appropriate comparison with the number of exposures predicted in the 
U.S. EEZ.
    The current SARs abundance estimate for Kogia spp. is substantially 
higher than that provided by Roberts et al. (2016). However, the data 
from which the SARs estimate is derived was not made available to 
Roberts et al. (Roberts et al., 2015h), and those more recent surveys 
reported observing substantially greater numbers of Kogia spp. than did 
earlier surveys (43 sightings, more than the combined total of 31 
reported from all surveys from 1992-2014 considered by Roberts et al. 
(2016)) (NMFS, 2011). A 2013 NOAA survey, also not available to the 
model authors, reported 68 sightings of Kogia spp. (NMFS, 2013a). In 
addition, the SARs report an increase in Kogia spp. strandings (92 from 
2001-05; 187 from 2007-11) (Waring et al., 2007; 2013). A simultaneous 
increase in at-sea observations and strandings suggests increased 
abundance of Kogia spp., though NMFS has not conducted any trend 
analysis (Waring et al., 2013). Therefore, we believe the most 
appropriate abundance estimate for use here is that currently reported 
by NMFS in the SARs. In fact, Waring et al. (2013) suggest that because 
this estimate was corrected for perception bias but not availability 
bias, the true estimate could be two to four times larger.
    Biologically Important Areas--Several biologically important areas 
for some marine mammal species are recognized in the survey areas in 
the mid- and south Atlantic. Critical habitat is designated for the 
North Atlantic right whale within the southeast United States (81 FR 
4838; January 27, 2016). Critical habitat is defined by section 3 of 
the ESA as (1) the specific areas within the geographical area occupied 
by the species, at the time it is listed, on which are found those 
physical or biological features (a) essential to the conservation of 
the species and (b) which may require special management considerations 
or protection; and (2) specific areas outside the geographical area 
occupied by the species at the time it is listed, upon a determination 
by the Secretary that such areas are essential for the conservation of 
the species. Critical habitat for the right whale in the southeast 
United States (i.e., Unit 2) encompasses calving habitat and is 
designated on the basis of the following essential features: (1) Calm 
sea surface conditions of Force 4 or less on the Beaufort Wind Scale; 
(2) sea surface temperatures from a minimum of 7[deg] C, and never more 
than 17[deg] C; and (3) water depths of 6 to 28 m, where these features 
simultaneously co-occur over contiguous areas of at least 231 nmi\2\ of 
ocean waters during the months of November through April. When these 
features are available, they are selected by right whale cows and 
calves in dynamic combinations that are suitable for calving, nursing, 
and rearing, and which vary, within the ranges specified, depending on 
factors such as weather and age of the calves.
    The area associated with such features includes nearshore and 
offshore waters of the southeastern United States, extending from Cape 
Fear, North Carolina south to 28[deg] N. The specific area designated 
as Unit 2 of critical habitat, as defined by regulation (81 FR 4838; 
January 27, 2016), is demarcated by rhumb lines connecting the specific 
points identified in 50 CFR 226.203(b)(2), as shown in Figure 2.

[[Page 63322]]

There is no critical habitat designated for any other species within 
the survey area.
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[GRAPHIC] [TIFF OMITTED] TN07DE18.002


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BILLING CODE 3510-22-C
    Biologically important areas for North Atlantic right whales in the 
mid- and south Atlantic were further described by LaBrecque et al. 
(2015). The authors describe an area of importance for reproduction 
that somewhat expands the boundaries of the critical habitat 
designation, including waters out to the 25-m isobath from Cape 
Canaveral to Cape Lookout from mid-November to mid-April, on the basis 
of habitat analyses (Good, 2008; Keller et al., 2012) and sightings 
data (e.g., Keller et al., 2006; Schulte and Taylor, 2012) indicating 
that sea surface temperatures between 13[deg] to 15[deg] C and water 
depths between 10-20 m are critical parameters for calving. Right 
whales leave northern feeding grounds in November and December to 
migrate along the continental shelf to the calving grounds or to 
unknown winter areas before returning to northern areas by late spring. 
Right whales are known to travel along the continental shelf, but it is 
unknown whether they use the entire shelf area or are restricted to 
nearshore waters (Schick et al., 2009; Whitt et al., 2013). LaBrecque 
et al. (2015) define an important area for migratory behavior on the 
basis of aerial and vessel-based survey data, photo-identification 
data, radio-tracking data, and expert judgment.
    As noted by LaBrecque et al. (2015), additional cetacean species 
are known to have strong links to bathymetric features, although there 
is currently insufficient information to specifically identify these 
areas. For example, pilot whales and Risso's dolphins aggregate at the 
shelf break in the survey area. These and other locations predicted as 
areas of high abundance (Roberts et al., 2016) form the basis of 
spatiotemporal restrictions on survey effort as described under 
``Mitigation.'' In addition, other data indicate potential areas of 
importance that are not yet fully described. Risch et al. (2014) 
describe minke whale presence offshore of the shelf break (evidenced by 
passive acoustic recorders), which may be indicative of a migratory 
area, while other data provides evidence that sei whales aggregate near 
meandering frontal eddies over the continental shelf in the Mid-
Atlantic Bight (Newhall et al., 2012).
    Unusual Mortality Events (UME)--A UME is defined under the MMPA as 
``a stranding that is unexpected; involves a significant die-off of any 
marine mammal population; and demands immediate response.'' From 1991 
to the present, there have been approximately twelve formally 
recognized UMEs affecting marine mammals in the survey area and 
involving species under NMFS's jurisdiction. A recently ended UME 
involved bottlenose dolphins. Three UMEs are ongoing and under 
investigation. These involve humpback whales, North Atlantic right 
whales, and minke whales. Specific information for each ongoing UME is 
provided below. There is currently no direct connection between the 
three UMEs, as there is no evident cause of stranding or death that is 
common across the three species involved in the different UMEs. 
Additionally, strandings across the three species are not clustering in 
space or time.
    Since January 2016, elevated humpback whale mortalities have 
occurred along the Atlantic coast from Maine through Florida (though 
there are only two records to date south of North Carolina). As of 
October 2018, partial or full necropsy examinations have been conducted 
on approximately half of the 84 known cases. Of the cases examined, 
approximately half had evidence of human interaction (ship strike or 
entanglement). Some of these investigated mortalities showed blunt 
force trauma or pre-mortem propeller wounds indicative of vessel 
strike, indicating a strike rate above the annual long-term average; 
however, these findings of pre-mortem vessel strike are not consistent 
across all of the whales examined and more research is needed. NOAA is 
consulting with researchers that are conducting studies on the humpback 
whale populations, and these efforts may provide information on changes 
in whale distribution and habitat use that could provide additional 
insight into how these vessel interactions occurred. Three previous 
UMEs involving humpback whales have occurred since 2000, in 2003, 2005, 
and 2006. More information is available at www.fisheries.noaa.gov/national/marine-life-distress/2016-2018-humpback-whale-unusual-mortality-event-along-atlantic-coast (accessed October 17, 2018).
    Since January 2017, elevated minke whale strandings have occurred 
along the Atlantic coast from Maine through South Carolina, with 
highest numbers in Massachusetts, Maine, and New York. As of October 
2018, partial or full necropsy examinations have been conducted on more 
than 60 percent of the 54 known cases. Preliminary findings in several 
of the whales have shown evidence of human interactions or infectious 
disease. These findings are not consistent across all of the whales 
examined, so more research is needed. As part of the UME investigation 
process, NOAA is assembling an independent team of scientists to 
coordinate with the Working Group on Marine Mammal Unusual Mortality 
Events to review the data collected, sample stranded whales, and 
determine the next steps for the investigation. More information is 
available at: www.fisheries.noaa.gov/national/marine-life-distress/2017-2018-minke-whale-unusual-mortality-event-along-atlantic-coast 
(accessed October 17, 2018).
    Elevated North Atlantic right whale mortalities began in June 2017, 
primarily in Canada. To date, there are a total of 20 confirmed dead 
stranded whales (12 in Canada; 8 in the United States), and 5 live 
whale entanglements in Canada have been documented. Full necropsy 
examinations have been conducted on 13 of the cases, with results 
currently available for seven of these that occurred in Canada (Daoust 
et al., 2017). Results indicate that two whales died from entanglement 
in fishing gear and, for four whales, necropsy findings were compatible 
with acute death due to trauma (although it is uncertain whether they 
were struck pre- or post-mortem) (Daoust et al., 2017). Several 
investigated cases are undetermined due to advanced decomposition. 
Overall, findings to date confirm that vessel strikes and fishing gear 
entanglement continue to be the key threats to recovery of North 
Atlantic right whales. In response, the Canadian government has enacted 
fishery closures to help reduce future entanglements and has modified 
fixed gear fisheries, as well as implementing temporary mandatory 
vessel speed restrictions in a portion of the Gulf of St. Lawrence. 
NOAA is cooperating with Canadian government officials as they 
investigate the incidents in Canadian waters. A previous UME involving 
right whales occurred in 1996. More information is available at: 
www.fisheries.noaa.gov/national/marine-life-distress/2017-2018-north-atlantic-right-whale-unusual-mortality-event (accessed October 17, 
2018).
    Beginning in July 2013, elevated strandings of bottlenose dolphins 
were observed along the Atlantic coast from New York to Florida. The 
investigation was closed in 2015, with the UME ultimately being 
attributed to cetacean morbillivirus (though additional contributory 
factors are under investigation; www.fisheries.noaa.gov/national/marine-life-distress/2013-2015-bottlenose-dolphin-unusual-mortality-event-mid-atlantic; accessed July 2, 2018). Dolphin strandings during 
2013-15 were greater than six times higher than the annual average from 
2007-12, with the most strandings reported from Virginia, North 
Carolina, and Florida. A

[[Page 63324]]

total of approximately 1,650 bottlenose dolphins stranded from June 
2013 to March 2015 and, additionally, a small number of individuals of 
several other cetacean species stranded during the UME and tested 
positive for morbillivirus (humpback whale, fin whale, minke whale, 
pygmy sperm whale, and striped dolphin). Only one offshore ecotype 
dolphin has been identified, meaning that over 99 percent of affected 
dolphins were of the coastal ecotype (D. Fauquier; pers. comm.). 
Research, to include analyses of stranding samples and post-UME 
monitoring and modeling of surviving populations, will continue in 
order to better understand the impacts of the UME on the affected 
stocks. Notably, an earlier major UME in 1987-88 was also caused by 
morbillivirus. Over 740 stranded dolphins were recovered during that 
event.
    Additional recent UMEs include various localized events with 
undetermined cause involving bottlenose dolphins (e.g., South Carolina 
in 2011; Virginia in 2009) and an event affecting common dolphins and 
Atlantic white-sided dolphins from North Carolina to New Jersey (2008; 
undetermined). For more information on UMEs, please visit: 
www.fisheries.noaa.gov/national/marine-life-distress/marine-mammal-unusual-mortality-events.
    Take Reduction Planning--Take reduction plans are designed to help 
recover and prevent the depletion of strategic marine mammal stocks 
that interact with certain U.S. commercial fisheries, as required by 
Section 118 of the MMPA. The immediate goal of a take reduction plan is 
to reduce, within six months of its implementation, the mortality and 
serious injury of marine mammals incidental to commercial fishing to 
less than the potential biological removal level. The long-term goal is 
to reduce, within five years of its implementation, the mortality and 
serious injury of marine mammals incidental to commercial fishing to 
insignificant levels, approaching a zero serious injury and mortality 
rate, taking into account the economics of the fishery, the 
availability of existing technology, and existing state or regional 
fishery management plans. Take reduction teams are convened to develop 
these plans.
    There are several take reduction plans in place for marine mammals 
in the survey areas of the mid- and south Atlantic. We described these 
here briefly in order to fully describe, in conjunction with referenced 
material, the baseline conditions for the affected marine mammal 
stocks. The Atlantic Large Whale Take Reduction Plan (ALWTRP) was 
implemented in 1997 to reduce injuries and deaths of large whales due 
to incidental entanglement in fishing gear. The ALWTRP is an evolving 
plan that changes as NMFS learns more about why whales become entangled 
and how fishing practices might be modified to reduce the risk of 
entanglement. It has several components, including restrictions on 
where and how gear can be set and requirements for entangling gears 
(i.e., trap/pot and gillnet gears). The ALWTRP addresses those species 
most affected by fishing gear entanglements, i.e., North Atlantic right 
whale, humpback whale, fin whale, and minke whale. Annual human-caused 
mortality exceeds PBR for the North Atlantic right whale and certain 
other ESA-listed whale species. More information is available online 
at: www.greateratlantic.fisheries.noaa.gov/protected/whaletrp/.
    NMFS implemented a Harbor Porpoise Take Reduction Plan (HPTRP) to 
reduce interactions between harbor porpoise and commercial gillnet gear 
in both New England and the mid-Atlantic. The HPTRP has several 
components including restrictions on where, when, and how gear can be 
set, and in some areas requires the use of acoustic deterrent devices. 
More information is available online at: 
www.greateratlantic.fisheries.noaa.gov/protected/porptrp/.
    The Atlantic Trawl Gear Take Reduction Team was developed to 
address the incidental mortality and serious injury of pilot whales, 
common dolphins, and white-sided dolphins incidental to Atlantic trawl 
fisheries. More information is available online at: 
www.greateratlantic.fisheries.noaa.gov/Protected/mmp/atgtrp/. 
Separately, NMFS established a Pelagic Longline Take Reduction Plan 
(PLTRP) to address the incidental mortality and serious injury of pilot 
whales in the mid-Atlantic region of the Atlantic pelagic longline 
fishery. The PLTRP includes a special research area, gear 
modifications, outreach material, observer coverage, and captains' 
communications. Pilot whales incur substantial incidental mortality and 
serious injury due to commercial fishing, and therefore are of 
particular concern. More information is available online at: 
www.nmfs.noaa.gov/pr/interactions/trt/pl-trt.html.

Marine Mammal Hearing

    Hearing is the most important sensory modality for marine mammals 
underwater, and exposure to anthropogenic sound can have deleterious 
effects. To appropriately assess the potential effects of exposure to 
sound, it is necessary to understand the frequency ranges marine 
mammals are able to hear. Current data indicate that not all marine 
mammal species have equal hearing capabilities (e.g., Richardson et 
al., 1995; Wartzok and Ketten, 1999; Au and Hastings, 2008). To reflect 
this, Southall et al. (2007) recommended that marine mammals be divided 
into functional hearing groups based on directly measured or estimated 
hearing ranges on the basis of available behavioral response data, 
audiograms derived using auditory evoked potential techniques, 
anatomical modeling, and other data. Note that no direct measurements 
of hearing ability have been successfully completed for mysticetes 
(i.e., low-frequency cetaceans). NMFS (2018) describes generalized 
hearing ranges for these marine mammal hearing groups. Generalized 
hearing ranges were chosen based on the approximately 65 dB threshold 
from the normalized composite audiograms, with the exception for lower 
limits for low-frequency cetaceans where the lower bound was deemed to 
be biologically implausible and the lower bound from Southall et al. 
(2007) retained. Pinniped functional hearing is not discussed here, as 
no pinnipeds are expected to be affected by the specified activity. The 
functional groups and the associated frequencies are indicated below 
(note that these frequency ranges correspond to the range for the 
composite group, with the entire range not necessarily reflecting the 
capabilities of every species within that group):
     Low-frequency cetaceans (mysticetes): Generalized hearing 
is estimated to occur between approximately 7 Hz and 35 kHz;
     Mid-frequency cetaceans (larger toothed whales, beaked 
whales, and most delphinids): Generalized hearing is estimated to occur 
between approximately 150 Hz and 160 kHz;
     High-frequency cetaceans (porpoises, river dolphins, and 
members of the genera Kogia and Cephalorhynchus; including two members 
of the genus Lagenorhynchus, on the basis of recent echolocation data 
and genetic data): Generalized hearing is estimated to occur between 
approximately 275 Hz and 160 kHz.
    For more detail concerning these groups and associated frequency 
ranges, please see NMFS (2018) for a review of available information. 
Thirty-four marine mammal species, all cetaceans, have the reasonable 
potential to co-occur with the survey activities. Please refer to Table 
2. Of the species that may

[[Page 63325]]

be present, seven are classified as low-frequency cetaceans (i.e., all 
mysticete species), 24 are classified as mid-frequency cetaceans (i.e., 
all delphinid and ziphiid species and the sperm whale), and three are 
classified as high-frequency cetaceans (i.e., harbor porpoise and Kogia 
spp.).

Potential Effects of the Specified Activities on Marine Mammals and 
Their Habitat

    In our Notice of Proposed IHAs, this section included a 
comprehensive summary and discussion of the ways that components of the 
specified activity may impact marine mammals and their habitat, 
including general background information on sound and specific 
discussion of potential effects to marine mammals from noise produced 
through use of airgun arrays. We do not repeat that discussion here, 
instead referring the reader to the Notice of Proposed IHAs. However, 
we do provide a more thorough discussion regarding potential impacts to 
marine mammal habitat via effects to prey species, as well as 
discussion of important new information regarding potential impacts to 
prey species produced since publication of our notice. The ``Estimated 
Take'' section later in this document includes a quantitative analysis 
of the number of individuals that are expected to be taken by this 
activity. The ``Negligible Impact Analyses and Determinations'' section 
will include an analysis of how these specific activities will impact 
marine mammals and will consider the content of this section, the 
``Estimated Take'' section, and the ``Mitigation'' section, to draw 
conclusions regarding the likely impacts of these activities on the 
reproductive success or survivorship of individuals and from that on 
the affected marine mammal populations.

Description of Active Acoustic Sound Sources

    In our Notice of Proposed IHAs, this section contained a brief 
technical background on sound, the characteristics of certain sound 
types, and on metrics used in the proposal inasmuch as the information 
is relevant to the specified activity and to a discussion of the 
potential effects of the specified activity on marine mammals found 
later in this document. Here, we summarize key information relating to 
terminology used in this notice.
    Amplitude (or ``loudness'') of sound is typically described using 
the relative unit of the decibel (dB). A sound pressure level (SPL) in 
dB is described as the ratio between a measured pressure and a 
reference pressure (for underwater sound, this is 1 microPascal 
([mu]Pa)). The source level (SL) represents the SPL referenced at a 
distance of 1 m from the source (referenced to 1 [mu]Pa), while the 
received level is the SPL at the listener's position (referenced to 1 
[mu]Pa).
    Root mean square (rms) is the quadratic mean sound pressure over 
the duration of an impulse. This measurement is often used in the 
context of discussing behavioral effects, in part because behavioral 
effects, which often result from auditory cues, may be better expressed 
through averaged units than by peak pressures. Sound exposure level 
(SEL; represented as dB re 1 [mu]Pa\2\-s) represents the total energy 
contained within a pulse, and considers both intensity and duration of 
exposure. Peak sound pressure (also referred to as zero-to-peak sound 
pressure or 0-p) is the maximum instantaneous sound pressure measurable 
in the water at a specified distance from the source, and is 
represented in the same units as the rms sound pressure. Another common 
metric is peak-to-peak sound pressure (pk-pk), which is the algebraic 
difference between the peak positive and peak negative sound pressures. 
Peak-to-peak pressure is typically approximately 6 dB higher than peak 
pressure (Southall et al., 2007).
    As described in more detail in our Notice of Proposed IHAs, airgun 
arrays are in a general sense considered to be omnidirectional sources 
of pulsed noise. Pulsed sound sources (as compared with non-pulsed 
sources) produce signals that are brief (typically considered to be 
less than one second), broadband, atonal transients (ANSI, 1986, 2005; 
Harris, 1998; NIOSH, 1998; ISO, 2003) and occur either as isolated 
events or repeated in some succession. Pulsed sounds are all 
characterized by a relatively rapid rise from ambient pressure to a 
maximal pressure value followed by a rapid decay period that may 
include a period of diminishing, oscillating maximal and minimal 
pressures, and generally have an increased capacity to induce physical 
injury as compared with sounds that lack these features. Airguns 
produce sound with energy in a frequency range from about 10-2,000 Hz, 
with most energy radiated at frequencies below 200 Hz. Although the 
amplitude of the acoustic wave emitted from the source is equal in all 
directions (i.e., omnidirectional), airgun arrays do possess some 
directionality due to different phase delays between guns in different 
directions. Airgun arrays are typically tuned to maximize functionality 
for data acquisition purposes, meaning that sound transmitted in 
horizontal directions and at higher frequencies is minimized to the 
extent possible.

Anticipated Effects on Marine Mammal Habitat

    We received numerous public comments regarding potential effects to 
marine mammal habitat, including to prey species, including some 
comments pointing out additional relevant literature and/or claiming 
that we had not adequately considered potential impacts to prey 
species. While we disagree that we had not adequately considered 
potential impacts to marine mammal habitat, particularly with regard to 
marine mammal prey, in response to public comment we did consider 
additional literature regarding potential impacts to prey species, as 
well as some new literature made available since publication of our 
Notice of Proposed IHAs (e.g., McCauley et al., 2017). Portions of this 
information were described in responses to comments above. We provide a 
revised summary of our review of available literature regarding impacts 
to prey species here (please see our Notice of Proposed IHAs for our 
discussions of potential effects to other aspects of marine mammal 
habitat, including acoustic habitat). Our overall conclusions regarding 
potential impacts of the specified activities on marine mammal habitat 
are unchanged. As stated in our Notice of Proposed IHAs, our review of 
the available information and the specific nature of the activities 
considered herein suggest that the activities associated with the 
planned actions are not likely to have more than short-term adverse 
effects on any prey habitat or populations of prey species or on the 
quality of acoustic habitat. Further, any impacts to marine mammal 
habitat are not expected to result in significant or long-term 
consequences for individual marine mammals, or to contribute to adverse 
impacts on their populations. Information supporting this conclusion is 
summarized below.
    Effects to Prey--As stated above, here we provide an updated and 
more detailed discussion of the available information regarding 
potential effects to prey, as well as additional support for our 
conclusion.
    Sound may affect marine mammals through impacts on the abundance, 
behavior, or distribution of prey species (e.g., crustaceans, 
cephalopods, fish, zooplankton). Marine mammal prey varies by species, 
season, and location and, for some, is not well documented. Here, we 
describe studies regarding the effects of noise on known marine mammal 
prey.

[[Page 63326]]

    Fish utilize the soundscape (see our Notice of Proposed IHAs for 
discussion of this concept) and components of sound in their 
environment to perform important functions such as foraging, predator 
avoidance, mating, and spawning (e.g., Zelick et al., 1999; Fay, 2009). 
Depending on their hearing anatomy and peripheral sensory structures, 
which vary among species, fishes hear sounds using pressure and 
particle motion sensitivity capabilities and detect the motion of 
surrounding water (Fay et al., 2008). The potential effects of airgun 
noise on fishes depends on the overlapping frequency range, distance 
from the sound source, water depth of exposure, and species-specific 
hearing sensitivity, anatomy, and physiology. Key impacts to fishes may 
include behavioral responses, hearing damage, barotrauma (pressure-
related injuries), and mortality.
    Fish react to sounds which are especially strong and/or 
intermittent low-frequency sounds, and behavioral responses such as 
flight or avoidance are the most likely effects. Short duration, sharp 
sounds can cause overt or subtle changes in fish behavior and local 
distribution. The reaction of fish to airguns depends on the 
physiological state of the fish, past exposures, motivation (e.g., 
feeding, spawning, migration), and other environmental factors. 
Hastings and Popper (2005) identified several studies that suggest fish 
may relocate to avoid certain areas of sound energy. Several studies 
have demonstrated that airgun sounds might affect the distribution and 
behavior of some fishes, potentially impacting foraging opportunities 
or increasing energetic costs (e.g., Fewtrell and McCauley, 2012; 
Pearson et al., 1992; Skalski et al., 1992; Santulli et al., 1999). One 
recent study found a 78 percent decline in snapper-grouper complex 
species abundance during evening hours at a reef habitat site off 
central North Carolina following an airgun survey (Paxton et al., 
2017). During the days prior to the survey passing, fish use of this 
habitat was highest during the same hours.
    However, our review shows that the bulk of studies indicate no or 
slight reaction to noise (e.g., Miller and Cripps, 2013; Dalen and 
Knutsen, 1987; Pena et al., 2013; Chapman and Hawkins, 1969; Wardle et 
al., 2001; Sara et al., 2007; Jorgenson and Gyselman, 2009; Blaxter et 
al., 1981; Cott et al., 2012; Boeger et al., 2006), and that, most 
commonly, while there are likely to be impacts to fish as a result of 
noise from nearby airguns, such effects will be temporary. For example, 
investigators reported significant, short-term declines in commercial 
fishing catch rate of gadid fishes during and for up to five days after 
seismic survey operations, but the catch rate subsequently returned to 
normal (Engas et al., 1996; Engas and Lokkeborg, 2002); other studies 
have reported similar findings (Hassel et al., 2004). Skalski et al. 
(1992) also found a reduction in catch rates--for rockfish (Sebastes 
spp.) in response to controlled airgun exposure--but suggested that the 
mechanism underlying the decline was not dispersal but rather decreased 
responsiveness to baited hooks associated with an alarm behavioral 
response. A companion study showed that alarm and startle responses 
were not sustained following the removal of the sound source (Pearson 
et al., 1992); therefore, Skalski et al. (1992) suggested that the 
effects on fish abundance may be transitory, primarily occurring during 
the sound exposure itself. In some cases, effects on catch rates are 
variable within a study, which may be more broadly representative of 
temporary displacement of fish in response to airgun noise (i.e., catch 
rates may increase in some locations and decrease in others) than any 
long-term damage to the fish themselves (Streever et al., 2016).
    While the findings of Paxton et al. (2017) may be interpreted as a 
significant shift in distribution that could compromise life history 
behaviors--as some commenters have done--we interpret these findings as 
corroborating prior studies indicating that typically a startle 
response or short-term displacement should be expected. In fact, the 
evening hours during which the decline in fish habitat use were 
recorded (via video recording) occurred on the same day that the airgun 
survey passed, and no subsequent data is presented to support an 
inference that the response was long-lasting. Additionally, given that 
the finding is based on video images, the lack of recorded fish 
presence does not support a conclusion that the fish actually moved 
away from the site or suffered any serious impairment. Other studies 
have been inconclusive regarding the abundance effects of airgun noise 
(Thomson et al., 2014).
    SPLs of sufficient strength have been known to cause injury to fish 
and fish mortality and, in some studies, fish auditory systems have 
been damaged by airgun noise (McCauley et al., 2003; Popper et al., 
2005; Song et al., 2008). (No mortality occurred to fish in any of 
these studies.) While experiencing a TTS, fish may be more susceptible 
to fitness impacts resulting from effects to communication, predator/
prey detection, etc. (Popper et al., 2014). However, in most fish 
species, hair cells in the ear continuously regenerate and loss of 
auditory function likely is restored when damaged cells are replaced 
with new cells (Smith, 2016). Halvorsen et al. (2012a) showed that a 
TTS of 4-6 dB was recoverable within 24 hours for one species. Impacts 
would be most severe when the individual fish is close to the source 
and when the duration of exposure is long--neither condition should be 
expected in relation to the specified activities.
    Injury caused by barotrauma can range from slight to severe and can 
cause death, and is most likely for fish with swim bladders. Barotrauma 
injuries have been documented during controlled exposure to impact pile 
driving (an impulsive noise source, as are airguns) (Halvorsen et al., 
2012b; Casper et al., 2013). For geophysical surveys, the sound source 
is constantly moving, and most fish would likely avoid the sound source 
prior to receiving sound of sufficient intensity to cause physiological 
or anatomical damage.
    Invertebrates appear to be able to detect sounds (Pumphrey, 1950; 
Frings and Frings, 1967) and are most sensitive to low-frequency sounds 
(Packard et al., 1990; Budelmann and Williamson, 1994; Lovell et al., 
2005; Mooney et al., 2010). Available data suggest that cephalopods are 
capable of sensing the particle motion of sounds and detect low 
frequencies up to 1-1.5 kHz, depending on the species, and so are 
likely to detect airgun noise (Kaifu et al., 2008; Hu et al., 2009; 
Mooney et al., 2010; Samson et al., 2014). Cephalopods have a 
specialized sensory organ inside the head called a statocyst that may 
help an animal determine its position in space (orientation) and 
maintain balance (Budelmann, 1992). Packard et al. (1990) showed that 
cephalopods were sensitive to particle motion, not sound pressure, and 
Mooney et al. (2010) demonstrated that squid statocysts act as an 
accelerometer through which particle motion of the sound field can be 
detected. Auditory injuries (lesions occurring on the statocyst sensory 
hair cells) have been reported upon controlled exposure to low-
frequency sounds, suggesting that cephalopods are particularly 
sensitive to low-frequency sound (Andre et al., 2011; Sole et al., 
2013); however, these controlled exposures involved long exposure to 
sounds dissimilar to airgun pulses (i.e., 2 hours of continuous 
exposure to 1-second sweeps, 50-400 Hz). Behavioral responses, such as 
inking and jetting, have also been reported upon exposure to low-

[[Page 63327]]

frequency sound (McCauley et al., 2000b; Samson et al., 2014).
    Impacts to benthic communities from impulsive sound generated by 
active acoustic sound sources are not well documented. There are no 
published data that indicate whether threshold shift injuries or 
effects of auditory masking occur in benthic invertebrates, and there 
are little data to suggest whether sounds from seismic surveys would 
have any substantial impact on invertebrate behavior (Hawkins et al., 
2014), though some studies have indicated no short-term or long-term 
effects of airgun exposure (e.g., Andriguetto-Filho et al., 2005; Payne 
et al., 2007; 2008; Boudreau et al., 2009). Exposure to airgun signals 
was found to significantly increase mortality in scallops, in addition 
to causing significant changes in behavioral patterns and disruption of 
hemolymph chemistry during exposure (Day et al., 2017). However, the 
implications of this finding are not straightforward, as the authors 
state that the observed levels of mortality were not beyond naturally 
occurring rates. Fitzgibbon et al. (2017) found significant changes to 
hemolymph cell counts in spiny lobsters subjected to repeated airgun 
signals, with the effects lasting up to a year post-exposure. However, 
despite the high levels of exposure, direct mortality was not observed. 
Further, in reference to the study, Day et al. (2016) stated that 
``[s]eismic surveys appear to be unlikely to result in immediate large 
scale mortality [ . . . ] and, on their own, do not appear to result in 
any degree of mortality'' and that ``[e]arly stage lobster embryos 
showed no effect from air gun exposure, indicating that at this point 
in life history, they are resilient to exposure and subsequent 
recruitment should be unaffected.''
    There is little information concerning potential impacts of noise 
on zooplankton populations. However, one recent study (McCauley et al., 
2017) investigated zooplankton abundance, diversity, and mortality 
before and after exposure to airgun noise, finding that the exposure 
resulted in significant depletion for more than half the taxa present 
and that there were two to three times more dead zooplankton after 
airgun exposure compared with controls for all taxa. The majority of 
taxa present were copepods and cladocerans; for these taxa, the range 
within which effects on abundance were detected was up to approximately 
1.2 km. In order to have significant impacts on r-selected species such 
as plankton, the spatial or temporal scale of impact must be large in 
comparison with the ecosystem concerned (McCauley et al., 2017). It is 
also possible that the findings reflect avoidance by zooplankton rather 
than mortality (McCauley et al., 2017). Therefore, the large scale of 
effect observed here is of concern--particularly where repeated noise 
exposure is expected--and further study is warranted.
    A modeling exercise was conducted as a follow-up to the McCauley et 
al. (2017) study, in order to assess the potential for impacts on ocean 
ecosystem dynamics and zooplankton population dynamics (Richardson et 
al., 2017). Richardson et al. (2017) found that for copepods with a 
short life cycle in a high-energy environment, a full-scale airgun 
survey would impact copepod abundance up to three days following the 
end of the survey, suggesting that effects such as those found by 
McCauley et al. (2017) would not be expected to be detectable 
downstream of the survey areas, either spatially or temporally. 
However, these findings are relevant for zooplankton with rapid 
reproductive cycles in areas where there is a high natural 
replenishment rate resulting from new water masses moving in, and the 
findings may not apply in lower-energy environments or for zooplankton 
with longer life-cycles. In fact, the study found that by turning off 
the current, as may reflect lower-energy environments, the time to 
recovery for the modelled population extended from several days to 
several weeks.
    In the absence of further validation of the McCauley et al. (2017) 
findings, if we assume a worst-case likelihood of severe impacts to 
zooplankton within approximately 1 km of the acoustic source, the large 
spatial scale and expected wide dispersal of survey vessels does not 
lead us to expect any meaningful follow-on effects to the prey base for 
odontocete predators (the region is not an important feeding area for 
taxa that feed directly on zooplankton, i.e., mysticetes). While the 
large scale of effect observed by McCauley et al. (2017) may be of 
concern, NMFS concludes that these findings indicate a need for more 
study, particularly where repeated noise exposure is expected--a 
condition unlikely to occur in relation to the time period in which the 
surveys considered for the five IHAs will take place.
    A recent review article concluded that, while laboratory results 
provide scientific evidence for high-intensity and low-frequency sound-
induced physical trauma and other negative effects on some fish and 
invertebrates, the sound exposure scenarios in some cases are not 
realistic to those encountered by marine organisms during routine 
seismic operations (Carroll et al., 2017). The review finds that there 
has been no evidence of reduced catch or abundance following seismic 
activities for invertebrates, and that there is conflicting evidence 
for fish with catch observed to increase, decrease, or remain the same. 
Further, where there is evidence for decreased catch rates in response 
to airgun noise, these findings provide no information about the 
underlying biological cause of catch rate reduction (Carroll et al., 
2017).
    As addressed earlier in ``Comments and Responses,'' some members of 
the public made strong assertions regarding the likely effects of 
airgun survey noise on marine mammal prey. These assertions included, 
for example, that the specified activities would harm fish and 
invertebrate species over the long-term, cause reductions in 
recruitment and effects to behavior that may reduce reproductive 
potential and foraging success and increase the risk of predation, and 
induce changes in community composition via such population-level 
impacts. We have addressed these claims both in our comment responses 
and in our review of the available literature, above. We also reviewed 
available information regarding populations of representative prey 
stocks in the northern Gulf of Mexico (GOM), which is the only U.S. 
location where marine seismic surveys are a routinely occurring 
activity. While we recognize the need for caution in assuming 
correlation between the ongoing survey activity in the GOM and the 
health of assessed stocks there, we believe this information has some 
value in informing the likelihood of population-level effects to prey 
species and, therefore, the likelihood that the specified activities 
would negatively impact marine mammal populations via effects to prey. 
We note that the information reported below is in context of managed 
commercial and recreational fishery exploitation, in addition to any 
other impacts (e.g., noise) on the stocks. The species listed below are 
known prey species for marine mammals and represent groups with 
different life histories and patterns of habitat use.
     Red snapper (Lutjanus campechanus): Red snapper are 
bottom-dwelling fish generally found at approximately 10-190 m deep 
that typically live near hard structures on the continental shelf that 
have moderate to high relief (for example, coral reefs, artificial 
reefs, rocks, ledges, and caves), sloping soft-bottom areas, and 
limestone deposits. Larval snapper swim freely within the water column. 
Increases in total and spawning stock biomass are

[[Page 63328]]

predicted beginning in about 1990 (Cass-Calay et al., 2015). Regional 
estimates suggest that recruitment in the west has generally increased 
since the 1980s, and has recently been above average, while recruitment 
in the east peaked in the mid-2000s, and has since declined. However, 
the most recent assessment suggests a less significant decline (to 
moderate levels) (Cass-Calay et al., 2015).
     Yellowfin tuna (Thunnus albacares): Yellowfin tuna are 
highly migratory, living in deep pelagic waters, and spawn in the GOM 
from May to August. However, we note that a single stock is currently 
assumed for the entire Atlantic, with additional spawning grounds in 
the Gulf of Guinea, Caribbean Sea, and off Cabo Verde. The most recent 
assessment indicates that spawning stock biomass for yellowfin tuna is 
stable or increasing somewhat and that, overall, the stock is near 
levels that produce the maximum sustainable yield (ICCAT, 2016).
     King mackerel (Scomberomorus cavalla): King mackerel are a 
coastal pelagic species, found in open waters near the coast in waters 
from approximately 35-180 m deep. King mackerel migrate in response to 
changes in water temperature, and spawn in shelf waters from May 
through October. Estimates of recruitment demonstrate normal cyclical 
patterns over the past 50 years, with a period of higher recruitment 
most recently (1990-2007) (SEDAR, 2014). Long-term spawning stock 
biomass patterns indicate that the spawning stock has been either 
rebuilding or remained relatively consistent over the last 20 years, 
with nothing indicating that the stock has declined in these recent 
decades (SEDAR, 2014).
    In summary, impacts of the specified activities will likely be 
limited to behavioral responses, the majority of prey species will be 
capable of moving out of the project area during surveys, a rapid 
return to normal recruitment, distribution, and behavior for prey 
species is anticipated, and, overall, impacts to prey species will be 
minor and temporary. Prey species exposed to sound might move away from 
the sound source, experience TTS, experience masking of biologically 
relevant sounds, or show no obvious direct effects. Mortality from 
decompression injuries is possible in close proximity to a sound, but 
only limited data on mortality in response to airgun noise exposure are 
available (Hawkins et al., 2014). The most likely impacts for most prey 
species in a given survey area would be temporary avoidance of the 
area. Surveys using towed airgun arrays move through an area relatively 
quickly, limiting exposure to multiple impulsive sounds. In all cases, 
sound levels would return to ambient once a survey moves out of the 
area or ends and the noise source is shut down and, when exposure to 
sound ends, behavioral and/or physiological responses are expected to 
end relatively quickly (McCauley et al., 2000b). The duration of fish 
avoidance of a given area after survey effort stops is unknown, but a 
rapid return to normal recruitment, distribution, and behavior is 
anticipated. While the potential for disruption of spawning 
aggregations or schools of important prey species can be meaningful on 
a local scale, the mobile and temporary nature of most surveys and the 
likelihood of temporary avoidance behavior suggest that impacts would 
be minor.
    Based on the information discussed herein, we reaffirm our 
conclusion that impacts of the specified activities are not likely to 
have more than short-term adverse effects on any prey habitat or 
populations of prey species. Further, any impacts to marine mammal 
habitat are not expected to result in significant or long-term 
consequences for individual marine mammals, or to contribute to adverse 
impacts on their populations.

Estimated Take

    This section provides information regarding the number of 
incidental takes authorized, which informs both NMFS's consideration of 
``small numbers'' and the negligible impact determinations.
    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).
    Anticipated takes would primarily be by Level B harassment, as use 
of the acoustic sources (i.e., airgun arrays) can result in disruption 
of behavioral patterns for individual marine mammals. There is also 
some potential for auditory injury (Level A harassment) to result for 
low- and high-frequency species due to the size of the predicted 
auditory injury zones for those species. We do not expect auditory 
injury to occur for mid-frequency species, as discussed in greater 
detail below. The required mitigation and monitoring measures are 
expected to minimize the severity of such taking to the extent 
practicable. It is unlikely that lethal takes would occur even in the 
absence of the mitigation and monitoring measures, and no such takes 
are anticipated or authorized. Below we describe how the authorized 
take was estimated using acoustic thresholds, sound field modeling, and 
marine mammal density data.

Acoustic Thresholds

    NMFS uses acoustic thresholds that identify the received level of 
underwater sound above which exposed marine mammals generally would be 
reasonably expected to exhibit disruption of behavioral patterns 
(equated to Level B harassment) or to incur PTS of some degree (equated 
to Level A harassment).
    Level B Harassment--Although available data are consistent with the 
basic concept that louder sounds evoke more significant behavioral 
responses than softer sounds, defining precise sound levels that will 
potentially disrupt behavioral patterns is difficult because responses 
depend on the context in which the animal receives the sound, including 
an animal's behavioral mode when it hears sounds (e.g., feeding, 
resting, or migrating), prior experience, and biological factors (e.g., 
age and sex). Some species, such as beaked whales, are known to be more 
highly sensitive to certain anthropogenic sounds than other species. 
Other contextual factors, such as signal characteristics, distance from 
the source, duration of exposure, and signal to noise ratio, may also 
help determine response to a given received level of sound. Therefore, 
levels at which responses occur are not necessarily consistent and can 
be difficult to predict (Southall et al., 2007; Ellison et al., 2012; 
Bain and Williams, 2006).
    However, based on the practical need to use a relatively simple 
threshold based on available information that is both predictable and 
measurable for most activities, NMFS has historically used a 
generalized acoustic threshold based on received level to estimate the 
onset of Level B harassment. These thresholds are 160 dB rms 
(intermittent sources, which include impulsive sources) and 120 dB rms 
(continuous sources). Airguns are impulsive sound sources; therefore, 
the 160 dB rms threshold is appropriate for use in evaluating effects 
from the specified activities.
    Level A Harassment--NMFS's Technical Guidance for Assessing the 
Effects of Anthropogenic Sound on

[[Page 63329]]

Marine Mammal Hearing (NMFS, 2018) identifies dual criteria to assess 
the potential for auditory injury (Level A harassment) to occur for 
different marine mammal groups (based on hearing sensitivity) as a 
result of exposure to noise. The technical guidance identifies the 
received levels, or thresholds, above which individual marine mammals 
are predicted to experience changes in their hearing sensitivity for 
all underwater anthropogenic sound sources, and reflects the best 
available science on the potential for noise to affect auditory 
sensitivity by:
     Dividing sound sources into two groups (i.e., impulsive 
and non-impulsive) based on their potential to affect hearing 
sensitivity;
     Choosing metrics that best address the impacts of noise on 
hearing sensitivity, i.e., peak sound pressure level (peak SPL) 
(reflects the physical properties of impulsive sound sources to affect 
hearing sensitivity) and cumulative sound exposure level (cSEL) 
(accounts for not only level of exposure but also duration of 
exposure); and
     Dividing marine mammals into hearing groups and developing 
auditory weighting functions based on the science supporting that not 
all marine mammals hear and use sound in the same manner.
    The premise of the dual criteria approach is that, while there is 
no definitive answer to the question of which acoustic metric is most 
appropriate for assessing the potential for injury, both the received 
level and duration of received signals are important to an 
understanding of the potential for auditory injury. Therefore, peak SPL 
is used to define a pressure criterion above which auditory injury is 
predicted to occur, regardless of exposure duration (i.e., any single 
exposure at or above this level is considered to cause auditory 
injury), and cSEL is used to account for the total energy received over 
the duration of sound exposure (i.e., both received level and duration 
of exposure) (Southall et al., 2007; NMFS, 2018). As a general 
principle, whichever criterion is exceeded first (i.e., results in the 
largest isopleth) would be used as the effective injury criterion 
(i.e., the more precautionary of the criteria). Note that cSEL acoustic 
threshold levels incorporate marine mammal auditory weighting 
functions, while peak pressure thresholds do not (i.e., flat or 
unweighted). Weighting functions for each hearing group (e.g., low-, 
mid-, and high-frequency cetaceans) are described in NMFS (2018).
    NMFS (2018) recommends 24 hours as a maximum accumulation period 
relative to cSEL thresholds. These thresholds were developed by 
compiling and synthesizing the best available science, and are provided 
in Table 3 below. The references, analysis, and methodology used in the 
development of the thresholds are described in NMFS (2018), and more 
information is available online at: www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance.

  Table 3--Exposure Criteria for Auditory Injury for Impulsive Sources
------------------------------------------------------------------------
                                                        Cumulative sound
           Hearing group            Peak pressure \1\    exposure level
                                           (dB)             \2\ (dB)
------------------------------------------------------------------------
Low-frequency cetaceans...........                219                183
Mid-frequency cetaceans...........                230                185
High-frequency cetaceans..........                202                155
------------------------------------------------------------------------
\1\ Referenced to 1 [mu]Pa; unweighted within generalized hearing range.
\2\ Referenced to 1 [mu]Pa\2\s; weighted according to appropriate
  auditory weighting function.

    NMFS considers these updated thresholds and associated weighting 
functions to be the best available information for assessing whether 
exposure to specific activities is likely to result in changes in 
marine mammal hearing sensitivity.

Sound Field Modeling

    BOEM's PEIS (BOEM, 2014a) provides information related to 
estimation of the sound fields that would be generated by potential 
geophysical survey activity on the mid- and south Atlantic OCS. We 
provide a brief summary of that modeling effort here; for more 
information, please see our Notice of Proposed IHAs. For full detail, 
please see Appendix D of BOEM's PEIS (Zykov and Carr, 2014 in BOEM, 
2014a). The acoustic modeling generated a three-dimensional acoustic 
propagation field as a function of source characteristics and physical 
properties of the ocean for later integration with marine mammal 
density information in an animal movement model to estimate potential 
acoustic exposures.
    The authors selected 15 modeling sites throughout BOEM's mid-
Atlantic and south Atlantic OCS planning areas for use in modeling 
predicted sound fields resulting from use of the airgun array. The 
water depth at the sites varied from 30-5,400 m. Two types of bottom 
composition were considered: Sand and clay, their selection depending 
on the water depth at the source. Twelve possible sound speed profiles 
for the water column were used to cover the variation of the sound 
velocity distribution in the water with location and season. Twenty-one 
distinct propagation scenarios resulted from considering different 
sound speed profiles at some of the modeling sites. Two acoustic 
propagation models were employed to estimate the acoustic field 
radiated by the sound sources. A version of JASCO Applied Science's 
Marine Operations Noise Model (MONM), based on the Range-dependent 
Acoustic Model (RAM) parabolic-equations model, MONM-RAM, was used to 
estimate the SELs for low-frequency sources (below 2 kHz) such as an 
airgun array. For more information on sound propagation model types, 
please see, e.g., Etter (2013). The model takes into account the 
geoacoustic properties of the sea bottom, vertical sound speed profile 
in the water column, range-dependent bathymetry, and the directivity of 
the source. The directional source levels for the airgun array were 
modeled using the Airgun Array Source Model (AASM) based on the 
specifications of the source such as the arrangement and volume of the 
guns, firing pressure, and depth below the sea surface. The modeled 
directional source levels were used as the input for the acoustic 
propagation model. For background information on major factors 
affecting underwater sound propagation, please see Zykov and Carr 
(2014).
    The modeling used a 5,400 in\3\ airgun array as a representative 
example. The array has dimensions of 16 x 15 m and consists of 18 air 
guns placed in three identical strings of six air guns each (please see 
Figure D-6 of Zykov and

[[Page 63330]]

Carr (2014)). The volume of individual air guns ranges from 105-660 
in\3\. Firing pressure for all elements is 2,000 psi. The depth below 
the sea surface for the array was set at 6.5 m. Please see Table 1 for 
a comparison to the airgun arrays planned for use by the applicant 
companies. Horizontal third-octave band directionality plots resulting 
from source modeling are shown in Figure D-8 of Zykov and Carr (2014). 
The estimated received levels are expressed in terms of the SEL metric 
over the duration of a single source pulse. For the purposes of this 
study, the SEL results were converted to the rms SPL metric using a 
range dependent conversion coefficient.
    Four depth regions were classified based on bathymetry: Shallow 
continental shelf (<60 m); continental shelf (60-150 m); continental 
slope (150-1,000 m); and deep ocean (>1,000 m). The modeling results 
show that the largest threshold radii are typically associated with 
sites in intermediate water depths (250 and 900 m). Low frequencies 
propagate relatively poorly in shallow water (i.e., water depths on the 
same order as or less than the wavelength). At intermediate water 
depths, this stripping of low-frequency sound no longer occurs, and 
longer-range propagation can be enhanced by the channeling of sound 
caused by reflection from the surface and seafloor (depending on the 
nature of the sound speed profile and sediment type). Table 4 shows 
scenario-specific modeling results for distances to the 160 dB level; 
results presented are for the 95 percent range to threshold.

                                 Table 4--Modeling Scenarios and Site-Specific Modeled Threshold Radii From BOEM's PEIS
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                        Threshold radii
         Scenario No.                     Site No.\1\            Water depth (m)            Season                  Bottom type             (m) \2\
--------------------------------------------------------------------------------------------------------------------------------------------------------
1.............................  1.............................              5,390  Winter..................  Clay....................              4,969
2.............................  2.............................              2,560  Winter..................  Clay....................              5,184
3.............................  3.............................                880  Winter..................  Sand....................              8,104
4.............................  4.............................                249  Winter..................  Sand....................              8,725
5.............................  5.............................                288  Winter..................  Sand....................              8,896
6.............................  1.............................              5,390  Spring..................  Clay....................              4,989
7.............................  6.............................              3,200  Spring..................  Clay....................              5,026
8.............................  3.............................                880  Spring..................  Sand....................              8,056
9.............................  7.............................                251  Spring..................  Sand....................              8,593
10............................  8.............................                249  Spring..................  Sand....................              8,615
11............................  1.............................              5,390  Summer..................  Clay....................              4,973
12............................  6.............................              3,200  Summer..................  Clay....................              5,013
13............................  3.............................                880  Summer..................  Sand....................              8,095
14............................  9.............................                275  Summer..................  Sand....................              9,122
15............................  10............................              4,300  Fall....................  Clay....................              5,121
16............................  11............................              3,010  Fall....................  Clay....................              5,098
17............................  12............................              4,890  Fall....................  Clay....................              4,959
18............................  13............................              3,580  Fall....................  Clay....................              5,069
19............................  3.............................                880  Fall....................  Sand....................              8,083
20............................  14............................                100  Fall....................  Sand....................              8,531
21............................  15............................                 51  Fall....................  Sand....................              8,384
                               -------------------------------------------------------------------------------------------------------------------------
    Mean......................  ..............................  .................  ........................  ........................              6,838
--------------------------------------------------------------------------------------------------------------------------------------------------------
Adapted from Tables D-21 and D-22 of Zykov and Carr (2014).
\1\ Please see Figure D-35 of Zykov and Carr (2014) for site locations.
\2\ Threshold radii to 160 dB (rms) SPL, 95 percent range.

    We provide this description of the modeling performed for BOEM's 
PEIS as a general point of reference for the surveys, and also because 
three of the applicant companies--TGS, CGG, and Western--directly used 
these results to inform their exposure modeling, rather than performing 
separate sound field modeling. As described by BOEM (2014a), the 
modeled array was selected to be representative of the large airgun 
arrays likely to be used by geophysical exploration companies in the 
mid- and south Atlantic OCS. Therefore, we use the BOEM (2014a) results 
as a reasonable proxy for those three companies (please see ``Detailed 
Description of Activities'' for further description of the acoustic 
sources planned for use by these three companies). ION and Spectrum 
elected to perform separate sound field modeling efforts, and these are 
described below.
    ION--ION provided information related to estimation of the sound 
fields that would be generated by their geophysical survey activity on 
the mid- and south Atlantic OCS. We provide a brief summary of that 
modeling effort here; for more information, please see our Notice of 
Proposed IHAs. For full detail, please see Appendix A of ION's 
application (Li, 2014; referred to hereafter as Appendix A of ION's 
application). ION plans to use a 36-element airgun array with a 6,420 
in\3\ total firing volume (please see ``Detailed Description of 
Activities'' for further description of ION's acoustic source). The 
modeling assumed that ION would operate from July to December. Sixteen 
representative sites were selected along survey track lines planned by 
ION for use in modeling predicted sound fields resulting from use of 
the airgun array (see Figure 2 in Appendix A of ION's application for 
site locations). Two acoustic propagation models were employed to 
estimate the acoustic field radiated by the sound sources. As was 
described above for BOEM's PEIS, the acoustic signature of the airgun 
array was predicted using AASM and MONM was used to calculate the sound 
propagation and acoustic field near each defined site. The modeling 
process follows generally that described previously for BOEM's PEIS. 
Key differences are the characteristics of the acoustic source (see 
Table 1), locations of the modeled sites, and the use of a restricted 
set of sound velocity profiles (e.g., fall and winter). Site-specific 
modeling results for distances to the 160 dB rms level were presented 
in Table 8 of our Notice of Proposed IHAs and are not reprinted here; 
mean result for the

[[Page 63331]]

95 percent range to threshold was 5,836 m.
    Spectrum--Spectrum provided information related to estimation of 
the sound fields that would be generated by their geophysical survey 
activity on the mid- and south Atlantic OCS. We provide a brief summary 
of that modeling effort here; for more information, please see our 
Notice of Proposed IHAs. For full detail, please see Appendix A of 
Spectrum's application (Frankel et al., 2015; referred to hereafter as 
Appendix A of Spectrum's application). Spectrum plans to use a 32-
element airgun array with a 4,920 in\3\ total firing volume (please see 
``Detailed Description of Activities'' for further description of 
Spectrum's acoustic source). Array characteristics were input into the 
GUNDALF model to calculate the source level and predict the array 
signature. The directivity pattern of the airgun array was calculated 
using the beamforming module in the CASS[hyphen]GRAB acoustic 
propagation model. These models provided source input information for 
the range[hyphen]dependent acoustic model (RAM), which was then used to 
predict acoustic propagation and estimate the resulting sound field. 
The RAM model creates frequency-specific, three-dimensional directivity 
patterns (sound field) based upon the size and location of each airgun 
in the array. As described previously, physical characteristics of the 
underwater environment (e.g., sound velocity profile, bathymetry, 
substrate composition) are critical to understanding acoustic 
propagation; 16 modeling locations were selected that span the acoustic 
conditions of the survey area. Spectrum elected to use sound velocity 
profiles for winter and spring and assumed that half of the survey 
would occur in winter and half in spring. Site-specific modeling 
results for distances to the 160 dB rms level were presented in Table 9 
of our Notice of Proposed IHAs and are not reprinted here; mean result 
for the 95 percent range to threshold was 9,775 m.

Marine Mammal Density Information

    The best available scientific information was considered in 
conducting marine mammal exposure estimates (the basis for estimating 
take). Historically, distance sampling methodology (Buckland et al., 
2001) has been applied to visual line-transect survey data to estimate 
abundance within large geographic strata (e.g., Fulling et al., 2003; 
Mullin and Fulling, 2004; Palka, 2006). Design-based surveys that apply 
such sampling techniques produce stratified abundance estimates and do 
not provide information at appropriate spatiotemporal scales for 
assessing environmental risk of a planned survey. To address this issue 
of scale, efforts were developed to relate animal observations and 
environmental correlates such as sea surface temperature in order to 
develop predictive models used to produce fine-scale maps of habitat 
suitability (e.g., Waring et al., 2001; Hamazaki, 2002; Best et al., 
2012). However, these studies generally produce relative estimates that 
cannot be directly used to quantify potential exposures of marine 
mammals to sound, for example. A more recent approach known as density 
surface modeling couples traditional distance sampling with 
multivariate regression modeling to produce density maps predicted from 
fine-scale environmental covariates (e.g., DoN, 2007; Becker et al., 
2014; Roberts et al., 2016).
    At the time the applications were initially developed, the best 
available information concerning marine mammal densities in the survey 
area was the U.S. Navy's Navy Operating Area (OPAREA) Density Estimates 
(NODEs) (DoN, 2007). These habitat-based cetacean density models 
utilized vessel-based and aerial survey data collected by NMFS from 
1998-2005 during broad-scale abundance studies. Modeling methodology is 
detailed in DoN (2007). A more advanced cetacean density modeling 
effort, described in Roberts et al. (2016), was ongoing during initial 
development of the applications, and the model outputs were made 
available to the applicant companies. All information relating to this 
effort was made publicly available in March 2016.
    Roberts et al. (2016) provided several key improvements with 
respect to the NODEs effort, by incorporating additional aerial and 
shipboard survey data from NMFS and from other organizations collected 
over the period 1992-2014, incorporating 60 percent more shipboard and 
500 percent more aerial survey hours than did NODEs; controlling for 
the influence of sea state, group size, availability bias, and 
perception bias on the probability of making a sighting; and modeling 
density from an expanded set of eight physiographic and 16 dynamic 
oceanographic and biological covariates. There are multiple reasons why 
marine mammals may be undetected by observers. Animals are missed 
because they are underwater (availability bias) or because they are 
available to be seen, but are missed by observers (perception and 
detection biases) (e.g., Marsh and Sinclair, 1989). Negative bias on 
perception or detection of an available animal may result from 
environmental conditions, limitations inherent to the observation 
platform, or observer ability. Therefore, failure to correct for these 
biases may lead to underestimates of cetacean abundance (e.g., NMFS's 
SAR estimates fail to correct for availability bias). Use of additional 
data was used to improve detection functions for taxa that were rarely 
sighted in specific survey platform configurations. The degree of 
underestimation would likely be particularly high for species that 
exhibit long dive times or are cryptic, such as sperm whales or beaked 
whales. In summary, consideration of additional survey data and an 
improved modeling strategy allowed for an increased number of taxa 
modeled and better spatiotemporal resolutions of the resulting 
predictions. In general, we consider the models produced by Roberts et 
al. (2016) to be the best available source of data regarding cetacean 
density in the Atlantic. More information, including the model results 
and supplementary information for each model, is available at 
seamap.env.duke.edu/models/Duke-EC-GOM-2015/.
    Aerial and shipboard survey data produced by the Atlantic Marine 
Assessment Program for Protected Species (AMAPPS) program provides an 
additional source of information regarding marine mammal presence in 
the survey areas. These surveys represent a collaborative effort 
between NMFS, BOEM, and the Navy. Although the cetacean density models 
described above do include survey data from 2010-14, the AMAPPS data 
for those years was not made available to the model authors. Future 
model updates will incorporate these data, but currently the AMAPPS 
data comprise a separate source of information (e.g., NMFS, 2010a, 
2011, 2012, 2013a, 2014, 2015a).
    Cetacean density predictions provided by the Roberts et al. (2016) 
models are in most cases limited to the U.S. EEZ. However, the planned 
survey areas extend beyond the EEZ out to 350 nmi. Because specific 
modeling results were not available for this region at the time the 
exposure estimates were developed, the Roberts et al. (2016) model 
predictions were extrapolated out to the additional area (described in 
further detail below). Newer modeling products regarding cetacean 
densities in areas of the western North Atlantic beyond the EEZ became 
available (Mannocci et al., 2017) following development of the exposure 
estimates; however, this information was not reasonably available to 
the applicants in

[[Page 63332]]

developing their applications or to NMFS in preparing the Notice of 
Proposed IHAs. Therefore, we retain use of the extrapolated density 
values from Roberts et al. (2016) in estimating potential exposures in 
the region beyond the EEZ; this approach remains reasonably 
representative of cetacean densities in the portion of the specific 
geographic region outside the EEZ.
    North Atlantic Right Whale--Following publication of our Notice of 
Proposed IHAs, we became aware of an effort by Roberts et al. to update 
certain density models, including for the North Atlantic right whale. 
In contrast to other new information that was not reasonably available 
to us in developing the exposure estimates discussed herein (e.g., 
Mannocci et al., 2017 and additional Roberts et al. model revisions 
(discussed below)), we determined that the revised North Atlantic right 
whale models represent a significant improvement to the available 
information. These updates greatly expanded the dataset used to derive 
density outputs, especially within the action area, as they 
incorporated both AMAPPs data as well as data from aerial surveys 
conducted by several organizations in the southeast United States. By 
including these additional data sources, the number of right whale 
sightings used to inform the models within the action area increased by 
over 2,500 sightings (approximately 40 sightings in the 2015 model 
versus approximately 2,560 sightings in the 2017 model) (Roberts et 
al., 2017). In addition, the updated models incorporated several 
improvements to minimize known biases and used an improved seasonal 
definition that more closely aligns with right whale biology. 
Importantly, the updated model outputs showed a strong relationship 
between right whale abundance in the action area and distance to shore 
out to approximately 80 km (Roberts et al., 2017)--the same 
relationship was indicated as being out to approximately 50 km by the 
previous model version (Roberts et al., 2016). As a result of these 
significant model improvements and in context of the significant 
concern regarding North Atlantic right whale status, we determined it 
necessary to produce revised exposure estimates for the North Atlantic 
right whale (described in further detail below). As stated by the 
authors, their goal in updating the right whale model was to re-examine 
all aspects of the model and make as many improvements as possible. 
This updated model represents the best available scientific information 
regarding North Atlantic right whale density and distribution.
    We note that, in addition to the models for North Atlantic right 
whales, Roberts et al. (2017) presented updated models for 10 
additional taxa (fin, humpback, minke, sei, and sperm whales; separate 
models for Cuvier's, Mesoplodont, and unidentified beaked whales; pilot 
whales; and harbor porpoise). While these models incorporate several 
improvements (additional data (although mostly outside of the action 
area), new seasonal definitions, updates to better correct for known 
biases), we evaluated the model outputs as being generally similar to 
those produced by Roberts et al. (2016). Thus, while the Roberts et al. 
(2017) models for these additional species likely represent minor 
improvements over the Roberts et al. (2016) models for these species, 
they are unlikely to result in meaningful differences if used in an 
exposure analysis. That is, we consider both the Roberts et al. (2016) 
and Roberts et al. (2017) model outputs the best available density 
estimates for these additional species, and estimates of exposure based 
on the outputs of one model are unlikely to be meaningfully different 
than estimates based on outputs from the other. Therefore, because 
these revised models were not available to us at the time of initial 
development of the exposure estimates and do not represent a 
significant improvement in the state of available scientific 
information, as do the updated right whale models, we did not request 
these updated models from the authors and retain use of the 2015 model 
version for these taxa.

Description of Exposure Estimates

    Here, we provide applicant-specific descriptions of the processes 
employed to estimate potential exposures of marine mammals to given 
levels of received sound. The discussions provided here are specific to 
estimated exposures at or above the criterion for Level B harassment 
(i.e., 160 dB rms); we provide a separate discussion below regarding 
our consideration of potential Level A harassment. We provide a brief 
summary of the exposure modeling process performed for BOEM's PEIS as a 
point of reference; for more information, please see our Notice of 
Proposed IHAs. For full detail, see Appendix E of the PEIS (BOEM, 
2014a).
    This description builds on the description of sound field modeling 
provided earlier in this section and in Appendix D of BOEM's PEIS. As 
described previously, 21 distinct acoustic propagation regions were 
defined. Reflecting seasonal differences in sound velocity profiles, 
these regions were specific to each season. Using the NODEs data, the 
average density of each species was then numerically determined for 
each region. However, the NODEs models do not provide outputs for the 
extended continental shelf areas seaward of the EEZ; therefore, known 
density information at the edge of the area modeled by NODEs was 
extrapolated to the remainder of the study area.
    The results of the acoustic modeling exercise (i.e., estimated 3D 
sound field) and the region-specific density estimates were then input 
into MAI's Acoustic Integration Model (AIM). AIM is a software package 
developed to predict the exposure of receivers (e.g., an animal) to any 
stimulus propagating through space and time through use of a four-
dimensional, individual-based, Monte Carlo-based statistical model. 
Within the model, simulated marine animals (i.e., animats) may be 
programmed to behave in specific ways on the basis of measured field 
data. An animat movement engine controls the geographic and vertical 
movements (e.g., speed and direction) of sound sources and animats 
through four dimensions (time and space) according to user inputs.
    Species-specific animats were created with programmed behavioral 
parameters describing dive depth, surfacing and dive durations, 
swimming speed, course change, and behavioral aversions (e.g., water 
too shallow). The programmed animats were then randomly distributed 
over a given bounded simulation area. Because the exact positions of 
sound sources and animals are not known in advance for proposed 
activities, multiple runs of realistic predictions are used to provide 
statistical validity to the simulated scenarios. Each species-specific 
simulation is seeded with a given density of animats. A separate 
simulation was created and run for each combination of location, 
movement pattern, and marine mammal species.
    A model run consists of a user-specified number of steps forward in 
time, in which each animat is moved according to the rules describing 
its behavior. For each time step of the model run, the received sound 
levels at each animat (i.e., each marine mammal) are calculated. AIM 
returns the movement patterns of the animats, and the received sound 
levels are calculated separately using the given acoustic propagation 
predictions at different locations. At the end of each time step, an 
animat ``evaluates'' its environment, including its 3D location, the 
time, and any received sound level.

[[Page 63333]]

    Animat positions relative to the acoustic source (i.e., range, 
bearing, and depth) were used to extract received level estimates from 
the acoustic propagation modeling results. The source levels, and 
therefore subsequently the received levels, include the embedded 
corrections for signal pulse length and M-weighting. M-weighting is a 
type of frequency weighting curve intended to reflect the differential 
potential for sound to affect marine mammals based on their sensitivity 
to the particular frequencies produced (Southall et al., 2007). Please 
see Appendix D of BOEM's PEIS for further description of the 
application of M-weighting filters. For each bearing, distance, and 
depth from the source, the received level values were expressed as SPLs 
(rms) with units of dB re 1[mu] Pa. These are then converted back to 
intensity and summed over the duration of the exercise to generate an 
integrated energy level, expressed in terms of dB re 1 [mu]Pa\2\-sec or 
dB SEL. The number of animats per species that exceeded a given 
criterion (e.g., 160 dB rms) may then be determined, and these results 
scaled according to the relationship of model-to-real world densities 
per species. That is, the exposure results are corrected using the 
actual species- and region-specific density derived from the density 
model outputs (as described above) to give real-world estimates of 
exposure to sound exceeding a given received level.
    As noted previously, the NODEs models (DoN, 2007) provided the best 
available information at the time of initial development for these 
applications. Outputs of the cetacean density models described by 
Roberts et al. (2016) were subsequently made available to the applicant 
companies, which, with the exception of CGG, had previously submitted 
applications. Two applicants (TGS and Western) elected to consider the 
new information and produced revised applications accordingly. CGG used 
the Roberts et al. (2016) models in developing their application. Two 
applicants (Spectrum and ION) declined to use the Roberts et al. (2016) 
density models. However, we worked with MAI--which performed the 
initial exposure modeling provided in the Spectrum and ION 
applications--to produce revised exposure estimates utilizing the 
outputs of the Roberts et al. (2016) density models.
    In order to revise the exposure estimates for Spectrum and ION, we 
first extracted appropriate density estimates from the Roberts et al. 
(2016) model outputs. Because both Spectrum and ION used modeling 
processes conceptually similar to that described above for BOEM's PEIS, 
these density estimates would replace those previously derived from the 
NODEs models in rescaling the exposure estimation results from those 
derived from animal movement modeling using a user-specified density. 
The steps involved in calculating mean marine mammal densities over the 
21 modeling areas used in both BOEM's PEIS and the applications were 
described in our Notice of Proposed IHAs, and are not repeated here. As 
was the case for the NODEs model outputs, the Roberts et al. (2016) 
model outputs are restricted to the U.S. EEZ. Therefore, we similarly 
extended the edge densities to cover the area outside of the data 
extent. This process was also described in our Notice of Proposed IHAs, 
and is not repeated here.
    Spectrum--Spectrum's sound field estimation process was previously 
described, and their exposure modeling process is substantially similar 
to that described above for BOEM's PEIS. Spectrum's exposure modeling 
process was described in full in our Notice of Proposed IHAs; please 
see that document for more detail. As described previously, Spectrum 
limited their analysis to winter and spring seasons and therefore used 
only ten of the 21 seasonal propagation acoustic regions. Half of the 
survey activity was assumed to occur in winter and half in spring.
    In summary, the original exposure results were obtained using AIM 
to model source and animat movements, with received SEL for each animat 
predicted at a 30-second time step. This predicted SEL history was used 
to determine the maximum SPL (rms or peak) and cSEL for each animat, 
and the number of exposures exceeding relevant criteria recorded. The 
number of exposures are summed for all animats to get the number of 
exposures for each species, with that summed value then scaled by the 
ratio of real-world density to the model density value. The final 
scaling value was the ratio of the length of the modeled survey line to 
the length of survey line in each modeling region. The exposure 
estimates provided in Spectrum's application were based on the NODEs 
model outputs. In order to make use of the best available information 
(i.e., Roberts et al. (2016)), we extracted species- and region-
specific density values as described above. These were provided to MAI 
in order to rescale the original exposure results produced using the 
seeded animat density; revised exposure estimates are shown in Table 6.
    As stated above, Spectrum notified NMFS on June 26, 2018, of a 
modification to their survey plan. Note that analysis corresponding 
with Spectrum's original survey plan is retained here, in ``Estimated 
Take.'' Please see ``Spectrum Survey Plan Modification'' for further 
information and for revised (and authorized) take numbers (Table 17) 
relating to Spectrum's modified survey plan.
    ION--ION's sound field estimation process was previously described, 
and their exposure modeling process is substantially similar to that 
described above for BOEM's PEIS (and for Spectrum). ION's exposure 
modeling process was described in full in our Notice of Proposed IHAs; 
please see that document for more detail. The same acoustic propagation 
regions described for BOEM's PEIS were used by ION for exposure 
modeling; however, ION limited their analysis to summer and fall 
seasons and therefore used only 11 of the 21 regions. Whichever season 
returned the higher number of estimated exposures for a given species 
was assumed to be the season in which the survey occurred, i.e., ION's 
requested take authorization corresponds to the higher of the two 
seasonal species-specific exposure estimates.
    In summary, the original exposure results were obtained using AIM 
to model source and animat movements, with received SEL for each animat 
predicted at a 30-second time step. This predicted SEL history was used 
to determine the maximum SPL (rms or peak) and cSEL for each animat, 
and the number of exposures exceeding relevant criteria recorded. The 
number of exposures are summed for all animats to get the number of 
exposures for each species, with that summed value then scaled by the 
ratio of real-world density to the model density value. The final 
scaling value was the ratio of the length of the modeled survey line to 
the length of survey line in each modeling region. As described above, 
the exposure estimates provided in ION's application were based on the 
NODEs model outputs. In order to make use of the best available 
information (i.e., Roberts et al. (2016)), we extracted species- and 
region-specific density values as described above. These were provided 
to MAI in order to rescale the original exposure results produced using 
the seeded animat density; revised exposure estimates are shown in 
Table 6.
    TGS--TGS did not conduct their own sound field modeling, instead 
relying on the sound field estimates provided by BOEM (2014a). For 
purposes of exposure modeling, TGS considered threshold radii for three 
depth bins: <880 m, 880-2,560 m, >2,560 m (note that there are no sound 
field modeling sites at depths between 880-2,560 m).

[[Page 63334]]

When considering the 21 modeling scenarios across the 15 sites, 
threshold radii shown in Table 4 break down evenly with 11 at depths 
<=880 m (mean threshold radius of 8,473 m) and ten at depths >=2,560 m 
(mean threshold radius of 5,040 m). Therefore, the overall mean for all 
scenarios of 6,838 m was used for estimating potential exposures for 
track lines occurring in water depths of 880-2,560 m.
    Regarding marine mammal occurrence, TGS considered both the Roberts 
et al. (2016) density models as well as the AMAPPS data. TGS stated 
that there are aspects of the Roberts et al. (2016) methodology that 
limit the model outputs' applicability to estimating marine mammal 
exposures to underwater sound and determined it appropriate to develop 
their own density estimates for certain species using AMAPPS data.
    As stated above, we believe the density models described by Roberts 
et al. (2016) provide the best available information at the time of our 
evaluation and recommend their use for species other than those 
expected to be extremely rare in a given area. However, TGS used the 
most recent observational data available in their alternative take 
estimation process conducted for seven of the affected species or 
groups. We acknowledge their concerns regarding use of predictive 
density models for species with relatively few observations in the 
survey area, e.g., that model-derived density estimates must be applied 
cautiously on a species-by-species basis with the recognition that in 
some cases the out-of-bound predictions could produce unrealistic 
results (Becker et al., 2014). Further, use of uniform (i.e., 
stratified) density models assumes a given density over a large 
geographic range which may include areas where the species has rarely 
or never been observed. For the seven species or species groups that 
TGS applied their alternative approach to (described below), five are 
modeled in whole or part through use of stratified models. We also 
acknowledge (as do Roberts et al. (2016)) that predicted habitat may 
not be occupied at expected densities or that models may not agree in 
all cases with known occurrence patterns, and that there is uncertainty 
associated with predictive habitat modeling (e.g., Becker et al., 2010; 
Forney et al., 2012). We determined that TGS' alternative approach (for 
seven species or species groups) is acceptable and, importantly, we 
recognize that there is no model or approach that is always the most 
appropriate and that there may be multiple approaches that may be 
considered acceptable (e.g., Box, 1979). Further detailed discussion on 
these topics was provided in our Notice of Proposed IHAs, and is not 
repeated here.
    In summary, TGS described the following issues in support of their 
development of an alternative approach for certain species:
     There are very few sightings of some species despite 
substantial survey effort;
     The modeling approach extrapolates based on habitat 
associations and assumes some species' occurrence in areas where they 
have never been or were rarely documented (despite substantial effort);
     In some cases, uniform density models spread densities of 
species with small sample sizes across large areas of the EEZ without 
regard to habitat, and;
     The most recent NOAA shipboard and aerial survey data 
(i.e., AMAPPS) were not included in model development.
    As a result of their general concerns regarding suitability of 
model outputs for exposure estimation, TGS developed a scheme related 
to the number of observations in the dataset available to Roberts et 
al. (2016) for use in developing the density models. Extremely rare 
species (i.e., less than four sightings in the survey area) were 
considered to have a very low probability of encounter, and it was 
assumed that the species might be encountered once. Therefore, a single 
group of the species was considered as expected to be exposed to sound 
exceeding the 160 dB rms harassment criterion. We agree with this 
approach for rarely occurring species and adopted it for all 
applicants, as described below.
    As described previously, marine mammal abundance has traditionally 
been estimated by applying distance sampling methodology (Buckland et 
al., 2001) to visual line-transect survey data. Buckland et al. (2001) 
recommend a minimum sample size of 60-80 sightings to provide 
reasonably robust estimates of density and abundance to fit the 
mathematical detection function required for this estimation; smaller 
sample sizes result in higher variance and thus less confidence and 
less accurate estimates. While we agree that TGS' approach is a 
reasonable one, we also note that the Buckland et al. (2001) 
recommendation that sample size should generally be at least 60-80 
should be considered as general guidance but not an absolute rule. 
Buckland et al. (2001) provide no theoretical proof for it and, in 
fact, it has not been followed as a rule in practice. Miller and Thomas 
(2015) provide an example where a detection function fitted to 30 
sightings resulted in a detection function with low bias. NMFS's line-
transect abundance estimates are in some cases based on many fewer 
sightings, e.g., stock assessments based on Palka (2012). For species 
meeting the Buckland et al. guideline within the survey area, TGS used 
Roberts et al. (2016)'s model. For species with fewer sightings (but 
with greater than four sightings in the survey area), TGS used what 
they refer to as ``Line Transect Theory'' in conjunction with AMAPPS 
data to estimate species density within the assumed 160 dB rms zone of 
ensonification.
    Nine species or species groups met TGS' requirement of having at 
least 60 sightings within the survey area in the dataset available to 
Roberts et al. (2016): Atlantic spotted dolphin, pilot whales, striped 
dolphin, beaked whales, bottlenose dolphin, Risso's dolphin, common 
dolphin, sperm whale, and humpback whale. The steps involved in the 
exposure estimation process for these species was described in full in 
our Notice of Proposed IHAs and is not repeated here.
    Seven species or species groups met TGS' criterion for conducting 
exposure modeling, but did not have the recommended 60 sightings in the 
survey area: Minke whale, fin whale, Kogia spp., harbor porpoise, 
pantropical spotted dolphin, clymene dolphin, and rough-toothed 
dolphin. For these species, TGS did not feel use of the density models 
was appropriate and developed a method using the available data instead 
(i.e., AMAPPS data as well as data considered by Roberts et al. (2016), 
excluding results of surveys conducted entirely outside of an area 
roughly coincident with the planned survey area); species-specific 
rationale is provided in section 6.3 of TGS' application. Please see 
section 6.3 of TGS' application for further details regarding the 
AMAPPS survey effort considered by TGS. Table 6-1 in TGS' application 
summarizes the AMAPPS data available for consideration by the authors. 
The steps involved in the exposure estimation process for these species 
was described in full in our Notice of Proposed IHAs and is not 
repeated here (see Table 6-4 in TGS' application for numerical process 
details).
    TGS initially proposed use of a mitigation source (i.e., 90-in\3\ 
airgun) for line turns and transits not exceeding three hours and 
produced exposure estimates specific to use of the mitigation source. 
As described in ``Mitigation,'' we do not allow use of the mitigation 
source; therefore, exposure estimates specific to use of a mitigation

[[Page 63335]]

gun would not actually occur. In their application, TGS provided 
exposure estimates specific to use of the full-power array and to use 
of the mitigation gun for the seven species for which the alternative 
approach was followed, but not for the nine species whose exposure 
estimates are based on the Roberts et al. (2016) density models (for 
the latter group, only a combined total was provided). Therefore, in 
our Notice of Proposed IHAs, we did not include mitigation gun exposure 
estimates for the former group but did for the latter group, noting 
exposure estimates for those nine species were slightly overestimated. 
However, following publication of our Notice of Proposed IHAs, TGS 
provided a breakdown for these species according to full-power array 
versus mitigation source; therefore, we have removed the estimates 
associated with use of the mitigation source for all species. Take 
authorization numbers provided for TGS (Table 6) reflect this 
appropriate adjustment.
    Western--Western's approach to estimating potential marine mammal 
exposures to underwater sound was identical to that described above for 
TGS; therefore, we do not provide a separate description for Western.
    Western also initially proposed use of a mitigation source for line 
turns and transits not exceeding three hours and produced exposure 
estimates specific to use of the mitigation source. Like TGS, Western's 
application provided information specific to use of the full-power 
array versus the mitigation source for the seven species for which the 
alternative approach was followed, but not for the nine species whose 
exposure estimates are based on the Roberts et al. (2016) density 
models (for the latter group, only a combined total was provided). 
However, unlike TGS, Western did not provide additional information 
following publication of our Notice of Proposed IHAs. Therefore, 
mitigation gun exposure estimates are included in the total for the 
latter group, and exposure estimates for those nine species are 
slightly overestimated.
    CGG--CGG used applicable results from BOEM's sound field modeling 
exercise in conjunction with the outputs of models described by Roberts 
et al. (2016) to inform their estimates of likely acoustic exposures. 
CGG's exposure modeling process was described in full in our Notice of 
Proposed IHAs; please see that document for more detail. Considering 
only the BOEM modeling sites that are in or near CGG's survey area 
provided a mean radial distance to the 160 dB rms criterion of 6,751 m 
(range 5,013-8,593 m). Taxon-specific model outputs, averaged over the 
six-month period planned for the survey (i.e., July-December) where 
relevant, were used with the assumed ensonification zone to provide 
estimates of marine mammal exposures to noise above the 160 dB rms 
threshold. Similar to other applicants, CGG performed an interpolation 
analysis to estimate density values for the portion of planned survey 
area outside the EEZ.
    North Atlantic Right Whale--As described above, given the current 
status of North Atlantic right whales, we re-evaluated available 
information subsequent to public review of our proposed IHAs. Finding 
that significant improvements were available to us, we determined it 
appropriate to re-estimate acoustic exposures specifically for right 
whales using the updated models. To do so, we relied on the sound field 
modeling results provided in BOEM's 2014 PEIS (see description above 
and Appendix D in BOEM (2014a)), as was previously done by TGS, CGG, 
and Western in their IHA applications. Using site- and season-specific 
radii to the 160 dB rms threshold (95 percent range, see Table 4 above 
or Table D-22 in BOEM (2014a)) and the total amount of trackline 
planned by each company within the acoustic modeling regions specified 
in BOEM's 2014 PEIS (see Appendix E, Table E-5 and Figures E-11 to E14 
in BOEM (2014a)), we calculated monthly, region-specific ensonified 
areas for each company as if their entire survey tracklines were 
completed in each month. Then, using the updated 2017 density model 
outputs (Roberts et al., 2017), we calculated average monthly regional 
right whale densities, which were then multiplied by the monthly 
ensonified areas. Finally, these data were averaged (annually or 
according to the planned operating window where appropriate) to 
estimate the average total exposure of North Atlantic right whales. In 
this way, we incorporated the seasonal variation in density of right 
whales since we do not know the exact distribution of survey effort 
within each company's operating window.
    Importantly, in these calculations we took into account the time-
area restrictions specified in ``Mitigation.'' For the year-round 
closure areas, data (i.e., ensonified areas and North Atlantic right 
whale densities) were not used to formulate exposure estimates since 
surveys would be completely prohibited within these areas. In the 
seasonal restriction areas, only data from months when the areas are 
open were used in calculating the exposure estimates. The final 
resulting exposure estimates then are based on the best available 
information on North Atlantic right whale densities within the action 
area (Roberts et al., 2017), fully take into account all time-area 
restrictions, and are specific to each company's tracklines and planned 
operating window (if specified). Take estimates shown in Table 6 for 
North Atlantic right whales reflect this analysis, and replace those 
previously estimated using different information and specified in our 
Notice of Proposed IHAs.
    Time-Area Restrictions--Following review of public comments, we 
conducted an analysis of expected take avoided due to implementation of 
the time-area restrictions described in ``Mitigation.'' To do this, we 
took an approach related to that previously described for right whales. 
In brief, we started with the existing take estimates as described in 
our Notice of Proposed IHAs and then calculated the take that would be 
avoided due to the planned restrictions. We then subtracted this from 
the originally proposed take to get our final take estimates. As 
described below, we took a slightly different approach for the sperm 
whale as compared with other species in that we accounted for the 
seasonal restriction of Area #4 (the ``Hatteras and North'' 
restriction; see ``Mitigation''). We did this because the area was 
designed in part specifically to benefit sperm whales, and because 
density model outputs are provided at monthly resolution for sperm 
whales, whereas density model outputs are provided at only annual 
resolution for beaked whales and pilot whales (Area #4 was also 
designed specifically to benefit these species). Take avoided due to 
seasonal restrictions, versus year-round closures, cannot be calculated 
for species for which only annual density outputs are available. For 
those species with monthly data availability but for which the seasonal 
restriction was not designed, we determined that the analysis was 
unlikely to result in meaningful changes to the take estimates.
    For sperm whales, we calculated the monthly density within each 
year-round closure area using the Roberts et al. (2016) model outputs 
and calculated the monthly ensonified area within each year-round 
closure for each company based on their planned tracklines and the 
radii to the 160 dB rms threshold. We then multiplied these monthly 
numbers by each other to estimate the monthly take avoided and, 
finally, computed the annual average of these avoided takes to estimate 
the overall take that would be avoided due to the year-round closures. 
For the seasonal

[[Page 63336]]

restrictions, only Area #4 (the ``Hatteras and North'' restriction; see 
``Mitigation'') was accounted for since it is the only seasonal 
restriction designed specifically to protect sperm whales. While we 
considered accounting for the North Atlantic right whale seasonal 
restriction, we opted not to since it primarily protects shallower 
waters where sperm whales are less likely to be found, and the added 
complication of incorporating the restriction was unlikely to result in 
meaningful changes to the overall take estimates for sperm whales. To 
account for Area #4, we calculated the change in take due to the 
restriction in a similar fashion to the year-round closures above, 
except that instead of calculating the change in take based on an 
annual average, we calculated the difference between the average take 
for when the area is open and when the area is closed in order to 
calculate the overall change in take due to restricting surveys within 
this area. As before, for these calculations we took into account 
specific survey timing where relevant but otherwise assumed the surveys 
could happen at any time of the year. The combined year-round and 
seasonal avoided takes were then subtracted from the originally 
proposed take authorizations described in our Notice of Proposed IHAs 
to calculate the final take estimates for sperm whales.
    For other species, a simpler approach was taken. First, we did not 
account for any seasonal restrictions, either because sufficient data 
is not available or because the seasonal restrictions' benefit in 
protecting species for which they were not specifically designed is 
unclear. Second, we did not recalculate density estimates specifically 
within the year-round closures, but instead relied on density estimates 
derived from the Roberts et al. (2016) model outputs for each acoustic 
modeling region used in BOEM's 2014 PEIS. Using these density 
estimates, we then followed the same procedure detailed above for sperm 
whales (multiplied monthly or seasonal densities by monthly or seasonal 
ensonified area, and compute annual or operating window average) to 
estimate the take that would be avoided due to the year-round closures. 
These avoided takes were then subtracted from the originally proposed 
take authorizations described in our Notice of Proposed IHAs to 
calculate the final take estimates.

Level A Harassment

    All requests for IHAs described herein were received prior to 
NMFS's original 2016 technical guidance and, therefore, did not reflect 
consideration of the currently best available information regarding the 
potential for auditory injury. In our Notice of Proposed IHAs, we 
described a process by which we estimated expected takes by Level A 
harassment in reflection of both NMFS's technical guidance and the 
specific survey characteristics (i.e., actual line-kms and specific 
airgun arrays planned for use) using modeled auditory injury exposure 
results found in BOEM's 2014 PEIS. The PEIS results were based on both 
the Southall et al. (2007) guidance (a precursor to NMFS's technical 
guidance) and the historical 180-dB rms criterion (which provides 
information relevant to a comparison to the likelihood of injurious 
exposure resulting from peak pressure). That process was described in 
our Notice of Proposed IHAs and is not repeated here. However, 
following review of public comments, we determined it appropriate to 
re-evaluate the analysis, as described below.
    In our Notice of Proposed IHAs, we acknowledged that the Level A 
exposure estimates provided therein--based on adjustments made to the 
results provided in BOEM's PEIS--were a rough approximation of 
potential exposures, with multiple limitations in reflection of the 
available information or lack thereof. For example, specific trackline 
locations planned by the applicant companies may differ somewhat from 
those considered in BOEM's PEIS, although it is likely that all 
portions of the survey area are considered in the PEIS analysis. More 
importantly, the PEIS exposure estimates were based on outputs of the 
NODEs models (DoN, 2007) available for BOEM's analysis versus the 
density models subsequently provided by Roberts et al. (2016), which we 
believe represent the best available information for purposes of 
exposure estimation. In addition, we noted that we did not attempt to 
approximate the probability of marine mammal aversion or to incorporate 
the effects of mitigation on the likelihood of Level A harassment. 
Following review of public comments, we reconsidered the likelihood of 
potential auditory injury, specific to each hearing group (i.e., low-
frequency, mid-frequency, and high-frequency), and re-evaluated the 
specific Level A harassment estimates presented in our Notice of 
Proposed IHAs. Here, we provide a revised analysis of likely takes by 
Level A harassment.
    Specifically, we determined that there is a low likelihood of take 
by Level A harassment for any species, and that this likelihood is 
primarily influenced by the specific hearing group. For mid- and high-
frequency cetaceans, potential auditory injury would be expected to 
occur on the basis of instantaneous exposure to peak pressure output 
from an airgun array, leading to a relatively straightforward 
consideration of the Level A harassment zone as an areal subset of the 
Level B harassment zone and, therefore, takes by Level A harassment as 
a subset of the previously enumerated takes by Level B harassment. 
However, for mid-frequency cetaceans, additional considerations of the 
small calculated Level A harassment zone size in conjunction with the 
properties of sound fields produced by arrays in the near field versus 
far field lead to a logical conclusion that Level A harassment is so 
unlikely for species in this hearing group as to be discountable. For 
low-frequency cetaceans, consideration of the likely potential for 
auditory injury is not straightforward, as such exposure would occur on 
the basis of the accumulation of energy output over time by an airgun 
array. Additional factors, such as the relative motion of source and 
receiver and the implementation of mitigation lead us to conclude that 
a quantitative evaluation of such potential, in light of the available 
information, does not make sense. Our evaluations for all three hearing 
groups are detailed below.
    As part of the exposure estimation process described in our Notice 
of Proposed IHAs, we calculated expected injury zones specific to each 
applicant's array for each hearing group relative to injury criteria 
for both the cSEL and peak pressure metrics. The results of this 
process, shown in Table 5, remain valid and were used to inform the 
revised estimates of take by Level A harassment described herein. For 
the cSEL metric, in order to incorporate the technical guidance's 
weighting functions over an array's full acoustic band, we obtained 
unweighted spectrum data (modeled in 1 Hz bands) for a reasonably 
equivalent acoustic source (i.e., a 36-airgun array with total volume 
of 6,600 in\3\). Using these data, we made adjustments (dB) to the 
unweighted spectrum levels, by frequency, according to the weighting 
functions for each relevant marine mammal hearing group. We then 
converted these adjusted/weighted spectrum levels to pressures 
(micropascals) 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 NMFS's User 
Spreadsheet (i.e., override the Spreadsheet's more simple weighting 
factor adjustment).
    When NMFS (2016) was published, in recognition of the fact that 
appropriate

[[Page 63337]]

isopleth distances could be more technically challenging to predict 
because of the duration component in the new thresholds, NMFS developed 
a User Spreadsheet that includes tools to help predict a simple 
isopleth that can be used in conjunction with marine mammal density to 
help predict exposures. For mobile sources, such as the surveys 
considered here, 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 (the 
``safe distance'' methodology discussed below). For more information 
about the User Spreadsheet, please see www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance.
    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 4.5 kn, shot intervals 
specified by the applicants, and pulse duration of 100 ms, we then 
calculated potential radial distances to auditory injury zones relative 
to the cSEL metric. We also calculated potential radial distances to 
auditory injury zones on the basis of maximum peak pressure using 
values provided by the applicants (Table 1) and assuming a simple model 
of spherical spreading propagation. We note that our Notice of Proposed 
IHAs contained an error. On page 26254 of that notice, we stated that 
the range of distances for injury zones relative to the cSEL metric was 
80-4,766 m. The correct range is 80-951 m; results are shown in Table 
5.

                                  Table 5--Estimated Auditory Injury Zones \1\
----------------------------------------------------------------------------------------------------------------
          Hearing group               Metric       Spectrum       ION          TGS        Western        CGG
----------------------------------------------------------------------------------------------------------------
Low-frequency...................  cSEL                   757          951          380           80          757
                                  peak                   224           79           63           71           50
Mid-frequency...................  cSEL                     0            0            0            0            0
                                  peak                    63           22           18           20           14
High-frequency..................  cSEL                     1            8            1            0            1
                                  peak                 1,585          562          447          501          355
Estimated near-field \2\........  .............          417          233          142           80          141
----------------------------------------------------------------------------------------------------------------
\1\ Radial isopleth distances presented in meters.
\2\ See discussion of ``near-field'' below.

    Based on our analysis of expected injury zones (Table 5), 
accumulation of energy is considered to be the predominant source of 
potential auditory injury for low-frequency cetaceans in all cases, 
while instantaneous exposure to peak pressure received levels is 
considered to be the predominant source of potential injury for both 
mid- and high-frequency cetaceans in all cases. Please note that 
discussion in this section and estimates of take by Level A harassment 
provided in Table 6 for Spectrum relate to Spectrum's original survey 
plan. Please see ``Spectrum Survey Plan Modification'' for additional 
discussion of Level A harassment reflecting Spectrum's modified survey 
plan.
    Mid-Frequency Cetaceans--For all mid-frequency cetaceans, following 
re-evaluation of the available scientific literature regarding the 
auditory sensitivity of mid-frequency cetaceans and the properties of 
airgun array sound fields, we do not expect any reasonable potential 
for Level A harassment to occur. For these species, the only potential 
injury zones (for all applicants) would be based on the peak pressure 
metric (Table 5). However, the estimated zone sizes for the 230 dB peak 
threshold for mid-frequency cetaceans range from only 14 m to 63 m. 
While in a theoretical modeling scenario it is possible for animats to 
engage with such small assumed zones around a notional point source 
and, subsequently, for these interactions to scale to predictions of 
real-world exposures given a sufficient number of predicted 24-hr 
survey days in confluence with sufficiently high predicted real-world 
animal densities--i.e., the modeling process that resulted in the 
predicted exposure estimates for mid-frequency cetaceans in BOEM's 
PEIS--this is not a realistic outcome. The source level of the array is 
a theoretical definition assuming a point source and measurement in the 
far-field of the source (MacGillivray, 2006). As described by Caldwell 
and Dragoset (2000), an array is not a point source, but one that spans 
a small area. In the far-field, individual elements in arrays will 
effectively work as one source because individual pressure peaks will 
have coalesced into one relatively broad pulse. The array can then be 
considered a ``point source.'' For distances within the near-field, 
i.e., approximately 2-3 times the array dimensions, pressure peaks from 
individual elements do not arrive simultaneously because the 
observation point is not equidistant from each element. The effect is 
destructive interference of the outputs of each element, so that peak 
pressures in the near-field will be significantly lower than the output 
of the largest individual element. Here, the 230 dB peak isopleth 
distances would in all cases be expected to be within the near-field of 
the arrays where the definition of source level breaks down. Therefore, 
actual locations within these distances (i.e., 14-63 m) of the array 
center where the sound level exceeds 230 dB peak SPL would not 
necessarily exist. In general, Caldwell and Dragoset (2000) suggest 
that the near-field for airgun arrays is considered to extend out to 
approximately 250 m.
    In order to provide quantitative support for this theoretical 
argument, we calculated expected maximum distances at which the near-
field would transition to the far-field (Table 5). For a specific array 
one can estimate the distance at which the near-field transitions to 
the far-field by:
[GRAPHIC] [TIFF OMITTED] TN07DE18.003

with the condition that D >> [lambda], and where D is the distance, L 
is the longest dimension of the array, and [lambda] is the wavelength 
of the signal (Lurton, 2002). Given that [lambda] can be defined by:
[GRAPHIC] [TIFF OMITTED] TN07DE18.004

where f is the frequency of the sound signal and v is the speed of the 
sound in the medium of interest, one can rewrite the equation for D as:
[GRAPHIC] [TIFF OMITTED] TN07DE18.005

and calculate D directly given a particular frequency and known speed 
of sound (here assumed to be 1,500

[[Page 63338]]

meters per second in water, although this varies with environmental 
conditions).
    To determine the closest distance to the arrays at which the source 
level predictions in Table 1 are valid (i.e., maximum extent of the 
near-field), we calculated D based on an assumed frequency of 1 kHz. A 
frequency of 1 kHz is commonly used in near-field/far-field 
calculations for airgun arrays (Zykov and Carr, 2014; MacGillivray, 
2006; NSF and USGS, 2011), and based on representative airgun spectrum 
data and field measurements of an airgun array used on the R/V Marcus 
G. Langseth, nearly all (greater than 95 percent) of the energy from 
airgun arrays is below 1 kHz (Tolstoy et al., 2009). Thus, using 1 kHz 
as the upper cut-off for calculating the maximum extent of the near-
field should reasonably represent the near-field extent in field 
conditions.
    If the largest distance to the peak sound pressure level threshold 
was equal to or less than the longest dimension of the array (i.e., 
under the array), or within the near-field, then received levels that 
meet or exceed the threshold in most cases are not expected to occur. 
This is because within the near-field and within the dimensions of the 
array, the source levels specified in Table 1 are overestimated and not 
applicable. In fact, until one reaches a distance of approximately 
three or four times the near-field distance the average intensity of 
sound at any given distance from the array is still less than that 
based on calculations that assume a directional point source (Lurton, 
2002). For example, an airgun array used on the R/V Marcus G. Langseth 
has an approximate diagonal of 29 m, resulting in a near-field distance 
of 140 m at 1 kHz (NSF and USGS, 2011). Field measurements of this 
array indicate that the source behaves like multiple discrete sources, 
rather than a directional point source, beginning at approximately 400 
m (deep site) to 1 km (shallow site) from the center of the array 
(Tolstoy et al., 2009), distances that are actually greater than four 
times the calculated 140-m near-field distance. Within these distances, 
the recorded received levels were always lower than would be predicted 
based on calculations that assume a directional point source, and 
increasingly so as one moves closer towards the array (Tolstoy et al., 
2009). Given this, relying on the calculated distances (Table 5) as the 
distances at which we expect to be in the near-field is a conservative 
approach since even beyond this distance the acoustic modeling still 
overestimates the actual received level.
    Within the near-field, in order to explicitly evaluate the 
likelihood of exceeding any particular acoustic threshold, one would 
need to consider the exact position of the animal, its relationship to 
individual array elements, and how the individual acoustic sources 
propagate and their acoustic fields interact. Given that within the 
near-field and dimensions of the array source levels would be below 
those in Table 1, we believe exceedance of the peak pressure threshold 
would only be possible under highly unlikely circumstances.
    Therefore, we expect the potential for Level A harassment of mid-
frequency cetaceans to be de minimis, even before the likely moderating 
effects of aversion and/or other compensatory behaviors (e.g., 
Nachtigall et al., 2018) are considered. We do not believe that Level A 
harassment is a likely outcome for any mid-frequency cetacean and do 
not authorize any Level A harassment for these species.
    Low-Frequency Cetaceans--For low-frequency cetaceans, we previously 
adjusted the BOEM PEIS estimates of potential Level A harassment to 
account for NMFS's technical acoustic guidance, as described in our 
Notice of Proposed IHAs. This process resulted in few estimated Level A 
harassment exposures for low-frequency cetaceans, i.e., 2-22 such 
exposures for humpback whales and 0-1 such exposures for minke whales, 
depending on array specifics, and zero exposures for right whales and 
fin whales (see Table 11 in our Notice of Proposed IHAs). The potential 
injury zones are relatively large for low-frequency cetaceans (up to 
951 m; Table 5); therefore, we expect that some Level A harassment may 
occur for the most commonly occurring low-frequency cetacean species 
(i.e., humpback, fin, and minke whales). However, we also note that 
injury on the basis of accumulation of energy is not a straightforward 
consideration of calculated zone size, as is consideration of injury on 
the basis of instantaneous peak pressure exposure. For example, 
observation of a whale at the distance calculated as being the ``injury 
zone'' using the cSEL criterion does not necessarily mean that the 
animal has in fact incurred auditory injury. Rather, the animal would 
have to be at the calculated distance (or closer) as the mobile source 
approaches, passes, and recedes from the exposed animal, being exposed 
to and accumulating energy from airgun pulses the entire time, as is 
implied by the name of the ``safe distance'' methodology by which such 
zone distances are calculated.
    Therefore, while we do believe that some limited Level A harassment 
of low-frequency cetaceans is likely unavoidable, despite the required 
mitigation measures (including ramp-up, shutdown upon detection within 
a 500-m exclusion zone for most mysticetes and shutdown upon detection 
of North Atlantic right whales within an expanded 1.5-km exclusion 
zone; see ``Mitigation''), we do not believe that the process followed 
in estimating potential Level A harassment in our Notice of Proposed 
IHAs is the most appropriate method. Further, upon re-evaluation of the 
results of that process, we do not have confidence in those results, 
which suggest that Level A harassment is likely for humpback whales but 
not for fin whales. Upon reconsideration of the available information, 
we note that the original information from BOEM's PEIS includes 
prediction of zero incidents of Level A harassment for fin whales while 
predicting non-zero results for all other mysticete species (see Table 
E-4 in BOEM (2014a))--a puzzling result that underlies the lack of 
predicted Level A harassment for fin whales in our Notice of Proposed 
IHAs. Therefore, we apply a simplified approach intended to acknowledge 
that there would likely be some minimal, yet difficult to accurately 
quantify, Level A harassment of certain mysticete species. As a result 
of the planned mitigation, including a seasonal restriction (or 
alternate methods of equivalent impact avoidance) and an expanded right 
whale exclusion zone of 1.5 km (intended to practicably avoid or 
minimize interaction with North Atlantic right whales; see 
``Mitigation''), we do not expect any reasonable potential for Level A 
harassment of North Atlantic right whales (consistent with the 
predictions of our original analysis). Any likely potential for the 
occurrence of Level A harassment is further minimized by likely 
aversion. For example, Ellison et al. (2016) demonstrated that animal 
movement models where no aversion probability was used overestimated 
the potential for high levels of exposure required for PTS by about 
five times.
    In order to account for the minimal likelihood of Level A 
harassment occurring for low-frequency cetaceans, we assume that in 
most cases during the course of conducting the survey at least one 
group of each species could incur auditory injury for all applicants 
other than Western. (As shown in Table 5, the calculated injury zone 
for Western is only 80 m. It is extremely unlikely that injury could 
occur given such a small

[[Page 63339]]

calculated zone, especially in context of a required 500-m exclusion 
zone.) We acknowledge that application of group size to estimation of 
take is more appropriate for take resulting from instantaneous exposure 
than it is for take resulting from the accumulation of energy, as any 
given group may disperse to some degree in a way that could lead to 
differing accumulation among individuals of the group. However, given 
the low likelihood of take by Level A harassment, small group sizes 
typical of mysticetes, and the likelihood that these individuals will 
remain within close distance of one another during the exposure, we 
believe that use of group size is appropriate in this context.
    For applicants other than Western, we consider both the size of the 
calculated potential injury zone and the total amount of planned survey 
effort. Spectrum, CGG, and ION have larger calculated potential injury 
zones, i.e., larger than the required 500-m exclusion zone (Table 5). 
However, ION has significantly less total survey effort (approximately 
half of what is planned by Spectrum and CGG; Table 1). TGS has a 
significantly smaller calculated injury zone, i.e., smaller than the 
required 500-m exclusion zone. However, at 380 m, the zone is 
sufficiently large that a whale could potentially occur within the zone 
without being observed in time to implement shutdown, and TGS's planned 
survey effort is substantially larger (approximately twice as large as 
that planned by Spectrum and CGG). Therefore, TGS' lower likelihood of 
causing injury is offset to some degree by their substantially greater 
survey effort. Finally, on the basis of expected taking by Level B 
harassment (Table 6), we see that the location and timing of CGG's 
planned survey effort results in significantly less potential 
interaction with humpback whales than for Spectrum and TGS.
    In summary, we conclude there is sufficiently reasonable potential 
for Level A harassment (even considering the likely effects of 
aversion) that it is appropriate to authorize take by Level A 
harassment for a minimum of one average size group of each relevant 
species (i.e., humpback, minke, and fin whales) for Spectrum, TGS, ION, 
and CGG. For Spectrum, in consideration of the calculated injury zone 
and level of planned effort, we increase this to two groups of each 
relevant species. For TGS, in consideration of the level of planned 
survey effort and despite the smaller calculated injury zone, we also 
increase this to two groups of each relevant species. For CGG, in 
consideration of the calculated injury zone and level of planned 
effort, we increase this to two groups for minke whales and fin whales 
only, given the lower potential for interaction with humpback whales. 
For ION, given the lower level of planned survey effort, we maintain 
the take authorization at one group of each relevant species. As a 
point of reference, we note that BOEM's PEIS analysis of potential 
takes by Level A harassment estimated that no more than 5.9 humpback 
whales could experience auditory injury in any given year for all 
surveys combined, despite a greater amount of assumed activity. 
Estimates were much less for all other species (see Table E-4 of BOEM 
(2014a)). As noted above, please see ``Spectrum Survey Plan 
Modification'' for additional discussion of Level A harassment 
reflecting Spectrum's modified survey plan, including Table 17, 
providing revised (and authorized) levels of take by Level A harassment 
for Spectrum.
    Average group size was determined by considering observational data 
from AMAPPS survey effort (e.g., NMFS, 2010a, 2011, 2012, 2013a, 2014, 
2015a). Average group sizes were as follows: Fin whale, 1.3 whales; 
humpback whale, 1.4 whales; minke whale, 1.2 whales. Therefore, we 
assume an average group size of two whales for each species. These take 
authorizations, which are subtracted from the estimates for take by 
Level B harassment to avoid double-counting, are shown in Table 6.
    High-Frequency Cetaceans--For high-frequency cetaceans (i.e., Kogia 
spp. and harbor porpoise), injury zones are based on instantaneous 
exposure to peak pressure and are larger than the expected near-field 
in all cases (i.e., 355-1,585 m). Therefore, we assume that Level A 
harassment is likely for some individuals of these species. In order to 
avoid consistency issues that may result when estimates of Level A 
harassment are based off of the results of a separate analysis that was 
founded in part on use of different density inputs, as was the case for 
the estimates of Level A harassment described in our Notice of Proposed 
IHAs, we simplified the analysis through use of the existing estimates 
of Level B harassment for each applicant. Under the assumption that 
some of these estimated exposures would in fact result in Level A 
harassment versus Level B harassment, we used applicant-specific 
calculated Level A and Level B harassment zones to generate estimates 
of the portion of estimated Level B harassment incidents that would be 
expected to be Level A harassment instead. For example, radial isopleth 
distances for Spectrum's calculated harassment zones are 1,585 m for 
Level A harassment and a mean of 9,775 m for Level B harassment, which 
we use to calculate relative area. On this basis, we assume that 
approximately 2.6 percent of estimated Level B harassment incidents 
would potentially be Level A harassment instead (for Spectrum). These 
final estimates, shown in Table 6, were then subtracted from the total 
take by Level B harassment. As noted for low-frequency cetaceans, we 
recognize that the effects of aversion would likely reduce these 
already low levels of Level A harassment.
    We recognize that the Level A exposure estimates provided here are 
a rough approximation of actual exposures; however, our intention is to 
use the information available to us, in reflection of available science 
regarding the potential for auditory injury, to acknowledge the 
potential for such outcomes in a way that is a reasonable 
approximation. Our revised analysis of potential Level A harassment, as 
reflected in Table 6, accomplishes this goal. As described in our 
Notice of Proposed IHAs, we note here that four of the five applicant 
companies (excepting Spectrum) declined to request authorization of 
take by Level A harassment. These four applicants claim, in summary, 
that injurious exposures will not occur largely due to the 
effectiveness of planned mitigation. While we agree that Level A 
harassment is unlikely for mid-frequency cetaceans, and that only 
limited injurious exposure is likely for low-frequency cetaceans, we do 
not find this assertion persuasive in all cases. Therefore, we are 
authorizing limited take by Level A harassment, as displayed in Table 
6.

Rare Species

    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 
would be encountered by assuming that these species might be 
encountered once by a given survey, and that Level A harassment would 
not occur for these species. 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

[[Page 63340]]

Atlantic (CETAP, 1982; Hansen et al, 1994; NMFS, 2010a, 2011, 2012, 
2013a, 2014, 2015a; Waring et al., 2007, 2015). We provided discussion 
for each of these species in our Notice of Proposed IHAs, and do not 
repeat the discussion here. For each of these species--sei, Bryde's, 
and blue whales; the northern bottlenose whale; killer whale, false 
killer whale, pygmy killer whale, and melon-headed whale; and spinner, 
Fraser's, and Atlantic white-sided dolphins--we authorize take 
equivalent to one group of each species per applicant (Table 6).
    Table 6 provides the authorized numbers of take by Level A and 
Level B harassment for each applicant. The numbers of authorized take 
reflect the expected exposure numbers provided in Table 10 of our 
Notice of Proposed IHAs, as derived by various methods described above, 
and additionally include take numbers for rare species that reflect the 
approach described above for average group size. In summary, the 
exposure estimates provided in Table 10 of our Notice of Proposed IHAs 
have been changed in reflection of the following: (1) Revised exposure 
estimates for North Atlantic right whales using Roberts et al. (2017); 
(2) removed exposure estimates specific to use of the disallowed 
mitigation source as necessary for certain species (TGS only); (3) 
removed estimated take avoided as a result of implementation of planned 
time-area restrictions; and (4) revised analysis of potential Level A 
harassment.
    As described previously, for most species these estimated exposure 
levels apply to a generic western North Atlantic stock defined by NMFS 
for management purposes. For the humpback and sei whale, any takes are 
assumed to occur to individuals of the species occurring in the 
specific geographic region (which may or may not be individuals from 
the Gulf of Maine and Nova Scotia stocks, respectively). For bottlenose 
dolphins, NMFS defines an offshore stock and multiple coastal stocks of 
dolphins, and we are not able to quantitatively determine the extent to 
which the estimated exposures may accrue to the oceanic versus various 
coastal stocks. However, because of the spatial distribution of planned 
survey effort and our prescribed mitigation, we assume that almost all 
incidents of take for bottlenose dolphins would accrue to the offshore 
stock.

                                                              Table 6--Numbers of Potential Instances of Incidental Take Authorized
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                      Spectrum \1\                   TGS                       ION                     Western                     CGG
                          Common name                          ---------------------------------------------------------------------------------------------------------------------------------
                                                                  Level A      Level B      Level A      Level B      Level A      Level B      Level A      Level B      Level A      Level B
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
North Atlantic right whale....................................            0            6            0            9            0            2            0            4            0            2
Humpback whale................................................            4           41            4           56            2            5            0           49            2            5
Minke whale...................................................            4          419            4          208            2           10            0          100            4          124
Bryde's whale.................................................            0            2            0            2            0            2            0            2            0            2
Sei whale.....................................................            0            2            0            2            0            2            0            2            0            2
Fin whale.....................................................            4          333            4        1,140            2            3            0          537            4           45
Blue whale....................................................            0            1            0            1            0            1            0            1            0            1
Sperm whale...................................................            0        1,077            0        3,579            0           16            0        1,941            0        1,304
Kogia spp.....................................................            5          200            5        1,216        \2\ 2           28            3          569        \2\ 2          238
Beaked whales.................................................            0        3,357            0       12,072            0          490            0        4,960            0        3,511
Northern bottlenose whale.....................................            0            4            0            4            0            4            0            4            0            4
Rough-toothed dolphin.........................................            0          201            0          261            0       \1\ 14            0          123            0          177
Common bottlenose dolphin.....................................            0       37,562            0       40,595            0        2,599            0       23,600            0        9,063
Clymene dolphin...............................................            0        6,459            0          821            0          252            0          391            0        6,382
Atlantic spotted dolphin......................................            0       16,926            0       41,222            0          568            0       18,724            0        6,596
Pantropical spotted dolphin...................................            0        1,632            0        1,470            0           78            0          690            0        1,566
Spinner dolphin...............................................            0           91            0           91            0           91            0           91            0           91
Striped dolphin...............................................            0        8,022            0       23,418            0          162            0        8,845            0        6,328
Common dolphin................................................            0       11,087            0       52,728            0          372            0       20,683            0        6,026
Fraser's dolphin..............................................            0          204            0          204            0          204            0          204            0          204
Atlantic white-sided dolphin..................................            0           48            0           48            0           48            0           48            0           48
Risso's dolphin...............................................            0          755            0        3,241            0           90            0        1,608            0          809
Melon-headed whale............................................            0           50            0           50            0           50            0           50            0           50
Pygmy killer whale............................................            0            6            0            6            0            6            0            6            0            6
False killer whale............................................            0           28            0           28            0           28            0           28            0           28
Killer whale..................................................            0            7            0            7            0            7            0            7            0            7
Pilot whales..................................................            0        2,765            0        8,902            0          199            0        4,682            0        1,964
Harbor porpoise...............................................           16          611        \2\ 3          322        \2\ 3           18        \2\ 3          152        \2\ 3           27
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Take numbers provided for Spectrum reflect Spectrum's original survey plan and are retained here in reference to the negligible impact and small numbers analyses provided later in this
  document for Spectrum. For revised (and authorized) take numbers for Spectrum reflecting their modified survey plan, please see ``Spectrum Survey Plan Modification.''
\2\ Exposure estimate increased to account for average group size observed during AMAPPS survey effort. For ION, estimated Level A harassment of Kogia spp. and harbor porpoise was zero and,
  for CGG, estimated Level A harassment of harbor porpoise was zero. We assume as a precaution that one group (as estimated from AMAPPS data) may incur Level A harassment.


[[Page 63341]]

Mitigation

    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.'' (While 
section 101(a)(5)(D) refers to ``least practicable impact,'' we 
hereafter use the term ``least practicable adverse impact,'' the term 
as it appears in section 101(a)(5)(A). Given the provision in which the 
language appears, and its similarity to the parallel provision in 
section 101(a)(5)(A), we believe that ``least practicable impact'' in 
section 101(a)(5)(D) similarly is referring to the requirement to 
prescribe the means of effecting the least practicable adverse impact, 
and we interpret the term in that manner.) Consideration of the 
availability of marine mammal species or stocks for taking for 
subsistence uses pertains only to Alaska, and is therefore not relevant 
here. NMFS does not have a regulatory definition for ``least 
practicable adverse impact.''
    In Conservation Council for Hawaii v. National Marine Fisheries 
Service, 97 F. Supp.3d 1210, 1229 (D. Haw. 2015), the Court stated that 
NMFS ``appear[s] to think [it] satisf[ies] the statutory `least 
practicable adverse impact' requirement with a `negligible impact' 
finding.'' More recently, expressing similar concerns in a challenge to 
an incidental take rule for U.S. Navy Operation of Surveillance Towed 
Array Sensor System Low Frequency Active Sonar (SURTASS LFA) (77 FR 
50290), the Ninth Circuit Court of Appeals in Natural Resources Defense 
Council (NRDC) v. Pritzker, 828 F.3d 1125, 1134 (9th Cir. 2016), 
stated, ``[c]ompliance with the `negligible impact' requirement does 
not mean there [is] compliance with the `least practicable adverse 
impact' standard.'' As the Ninth Circuit noted in its opinion, however, 
the Court was interpreting the statute without the benefit of NMFS's 
formal interpretation. We state here explicitly that NMFS is in full 
agreement that the ``negligible impact'' and ``least practicable 
adverse impact'' requirements are distinct, even though both statutory 
standards refer to species and stocks. With that in mind, we provide 
further explanation of our interpretation of least practicable adverse 
impact, and explain what distinguishes it from the negligible impact 
standard. This discussion is consistent with, and expands upon, 
previous rules we have issued (such as the Navy Gulf of Alaska rule (82 
FR 19530; April 27, 2017)).
    Before NMFS can issue an incidental take authorization under 
sections 101(a)(5)(A) or (D) of the MMPA, it must make a finding that 
the taking will have a ``negligible impact'' on the affected ``species 
or stocks'' of marine mammals. NMFS's and U.S. Fish and Wildlife 
Service's implementing regulations for section 101(a)(5) both define 
``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 and 50 CFR 
18.27(c)). Recruitment (i.e., reproduction) and survival rates are used 
to determine population growth rates \1\ and, therefore are considered 
in evaluating population level impacts.
---------------------------------------------------------------------------

    \1\ A growth rate can be positive, negative, or flat.
---------------------------------------------------------------------------

    Not every population-level impact violates the negligible impact 
requirement. The negligible impact standard does not require a finding 
that the anticipated take will have ``no effect'' on population numbers 
or growth rates. The statutory standard does not require that the same 
recovery rate be maintained, rather that no significant effect on 
annual rates of recruitment or survival occurs. The key factor is the 
significance of the level of impact on rates of recruitment or 
survival. See 54 FR 40338, 40341-42 (September 29, 1989).
    While some level of impact on population numbers or growth rates of 
a species or stock may occur and still satisfy the negligible impact 
requirement--even without consideration of mitigation--the least 
practicable adverse impact provision separately requires NMFS to 
prescribe means of effecting the least practicable adverse impact on 
such species or stock and its habitat, paying particular attention to 
rookeries, mating grounds, and areas of similar significance. 50 CFR 
216.102(b). These are typically identified as mitigation measures.\2\
---------------------------------------------------------------------------

    \2\ For purposes of this discussion we omit reference to the 
language in the standard for least practicable adverse impact that 
says we also must mitigate for subsistence impacts because they are 
not at issue in these actions.
---------------------------------------------------------------------------

    The negligible impact and least practicable adverse impact 
standards in the MMPA both call for evaluation at the level of the 
``species or stock.'' The MMPA does not define the term ``species.'' 
However, Merriam-Webster Dictionary defines ``species'' to include 
``related organisms or populations potentially capable of 
interbreeding.'' See www.merriam-webster.com/dictionary/species 
(emphasis added). The MMPA defines ``stock'' as a group of marine 
mammals of the same species or smaller taxa in a common spatial 
arrangement that interbreed when mature. 16 U.S.C. 1362(11). The 
definition of ``population'' is ``a group of interbreeding organisms 
that represents the level of organization at which speciation begins.'' 
www.merriam-webster.com/dictionary/population. The definition of 
``population'' is strikingly similar to the MMPA's definition of 
``stock,'' with both involving groups of individuals that belong to the 
same species and located in a manner that allows for interbreeding. In 
fact, the term ``stock'' in the MMPA is interchangeable with the 
statutory term ``population stock.'' 16 U.S.C. 1362(11). Thus, the MMPA 
terms ``species'' and ``stock'' both relate to populations, and it is 
therefore appropriate to view both the negligible impact standard and 
the least practicable adverse impact standard, both of which call for 
evaluation at the level of the species or stock, as having a 
population-level focus.
    This interpretation is consistent with Congress's statutory 
findings for enacting the MMPA, nearly all of which are most applicable 
at the species or stock (i.e., population) level. See 16 U.S.C. 1361 
(finding that it is species and population stocks that are or may be in 
danger of extinction or depletion; that it is species and population 
stocks that should not diminish beyond being significant functioning 
elements of their ecosystems; and that it is species and population 
stocks that should not be permitted to diminish below their optimum 
sustainable population level). Annual rates of recruitment (i.e., 
reproduction) and survival are the key biological metrics used in the 
evaluation of population-level impacts, and accordingly these same 
metrics are also used in the evaluation of population level impacts for 
the least practicable adverse impact standard.
    Recognizing this common focus of the least practicable adverse 
impact and negligible impact provisions on the ``species or stock'' 
does not mean we conflate the two standards; despite some common 
statutory language, we recognize the two provisions are different and 
have different functions. First, a negligible impact finding is 
required before NMFS can issue an incidental take authorization. 
Although it is acceptable to use the mitigation measures to reach a 
negligible impact finding (see 50 CFR 216.104(c)), no amount of 
mitigation can enable NMFS

[[Page 63342]]

to issue an incidental take authorization for an activity that still 
would not meet the negligible impact standard. Moreover, even where 
NMFS can reach a negligible impact finding--which we emphasize does 
allow for the possibility of some ``negligible'' population-level 
impact--the agency must still prescribe measures that will effect the 
least practicable amount of adverse impact upon the affected species or 
stock.
    Section 101(a)(5)(D)(ii)(I) (like section 101(a)(5)(A)(i)(II)) 
requires NMFS to issue, in conjunction with its authorization, 
binding--and enforceable--restrictions setting forth how the activity 
must be conducted, thus ensuring the activity has the ``least 
practicable adverse impact'' on the affected species or stocks. In 
situations where mitigation is specifically needed to reach a 
negligible impact determination, section 101(a)(5)(D)(ii)(I) also 
provides a mechanism for ensuring compliance with the ``negligible 
impact'' requirement. Finally, we reiterate that the least practicable 
adverse impact standard also requires consideration of measures for 
marine mammal habitat, with particular attention to rookeries, mating 
grounds, and other areas of similar significance, and for subsistence 
impacts; whereas the negligible impact standard is concerned solely 
with conclusions about the impact of an activity on annual rates of 
recruitment and survival.\3\
---------------------------------------------------------------------------

    \3\ Mitigation may also be appropriate to ensure compliance with 
the ``small numbers'' language in MMPA sections 101(a)(5)(A) and 
(D).
---------------------------------------------------------------------------

    In NRDC v. Pritzker, the Court stated, ``[t]he statute is properly 
read to mean that even if population levels are not threatened 
significantly, still the agency must adopt mitigation measures aimed at 
protecting marine mammals to the greatest extent practicable in light 
of military readiness needs.'' Id. at 1134 (emphases added). This 
statement is consistent with our understanding stated above that even 
when the effects of an action satisfy the negligible impact standard 
(i.e., in the Court's words, ``population levels are not threatened 
significantly''), still the agency must prescribe mitigation under the 
least practicable adverse impact standard. However, as the statute 
indicates, the focus of both standards is ultimately the impact on the 
affected ``species or stock,'' and not solely focused on or directed at 
the impact on individual marine mammals.
    We have carefully reviewed and considered the Ninth Circuit's 
opinion in NRDC v. Pritzker in its entirety. While the Court's 
reference to ``marine mammals'' rather than ``marine mammal species or 
stocks'' in the italicized language above might be construed as a 
holding that the least practicable adverse impact standard applies at 
the individual ``marine mammal'' level, i.e., that NMFS must require 
mitigation to minimize impacts to each individual marine mammal unless 
impracticable, we believe such an interpretation reflects an incomplete 
appreciation of the Court's holding. In our view, the opinion as a 
whole turned on the Court's determination that NMFS had not given 
separate and independent meaning to the least practicable adverse 
impact standard apart from the negligible impact standard, and further, 
that the Court's use of the term ``marine mammals'' was not addressing 
the question of whether the standard applies to individual animals as 
opposed to the species or stock as a whole. We recognize that while 
consideration of mitigation can play a role in a negligible impact 
determination, consideration of mitigation measures extends beyond that 
analysis. In evaluating what mitigation measures are appropriate, NMFS 
considers the potential impacts of the specified activity, the 
availability of measures to minimize those potential impacts, and the 
practicability of implementing those measures, as we describe below.
    Given the NRDC v. Pritzker decision, we discuss here how we 
determine whether a measure or set of measures meets the ``least 
practicable adverse impact'' standard. Our separate analysis of whether 
the take anticipated to result from applicants' activities satisfies 
the ``negligible impact'' standard appears in the section ``Negligible 
Impact Analyses and Determinations'' below.
    Our evaluation of potential mitigation measures includes 
consideration of two primary factors:
    (1) The manner in which, and the degree to which, implementation of 
the potential measure(s) is expected to reduce adverse impacts to 
marine mammal species or stocks, their habitat, and their availability 
for subsistence uses (when relevant). This analysis considers such 
things as the nature of the potential adverse impact (such as 
likelihood, scope, and range), the likelihood that the measure will be 
effective if implemented, and the likelihood of successful 
implementation.
    (2) The practicability of the measure for applicant implementation. 
Practicability of implementation may consider such things as cost, 
impact on operations, personnel safety, and practicality of 
implementation.
    While the language of the least practicable adverse impact standard 
calls for minimizing impacts to affected species or stocks, we 
recognize that the reduction of impacts to those species or stocks 
accrues through the application of mitigation measures that limit 
impacts to individual animals. Accordingly, NMFS's analysis focuses on 
measures designed to avoid or minimize impacts on marine mammals from 
activities that are likely to increase the probability or severity of 
population-level effects.
    While complete information on impacts to species or stocks from a 
specified activity is not available for every activity type, and 
additional information would help NMFS better understand how specific 
disturbance events affect the fitness of individuals of certain 
species, there have been significant improvements in understanding the 
process by which disturbance effects are translated to the population. 
With recent scientific advancements (both marine mammal energetic 
research and the development of energetic frameworks), the relative 
likelihood or degree of impacts on species or stocks may typically be 
predicted given a detailed understanding of the activity, the 
environment, and the affected species or stocks. This same information 
is used in the development of mitigation measures and helps us 
understand how mitigation measures contribute to lessening effects to 
species or stocks. We also acknowledge that there is always the 
potential that new information, or a new recommendation that we had not 
previously considered, becomes available and necessitates re-evaluation 
of mitigation measures (which may be addressed through adaptive 
management) to see if further reductions of population impacts are 
possible and practicable.
    In the evaluation of specific measures, the details of the 
specified activity will necessarily inform each of the two primary 
factors discussed above (expected reduction of impacts and 
practicability), and will be carefully considered to determine the 
types of mitigation that are appropriate under the least practicable 
adverse impact standard. Analysis of how a potential mitigation measure 
may reduce adverse impacts on a marine mammal stock or species and 
practicability of implementation are not issues that can be 
meaningfully evaluated through a yes/no lens. The manner in which, and 
the degree to which, implementation of a measure is expected to reduce 
impacts, as well as its practicability, can vary widely. For example, a 
time-area

[[Page 63343]]

restriction could be of very high value for decreasing population-level 
impacts (e.g., avoiding disturbance of feeding females in an area of 
established biological importance) or it could be of lower value (e.g., 
decreased disturbance in an area of high productivity but of less 
firmly established biological importance). Regarding practicability, a 
measure might involve operational restrictions that completely impede 
the operator's ability to acquire necessary data (higher impact), or it 
could mean additional incremental delays that increase operational 
costs but still allow the activity to be conducted (lower impact). A 
responsible evaluation of ``least practicable adverse impact'' will 
consider the factors along these realistic scales. Expected effects of 
the activity and of the mitigation as well as status of the stock all 
weigh into these considerations. Accordingly, the greater the 
likelihood that a measure will contribute to reducing the probability 
or severity of adverse impacts to the species or stock or their 
habitat, the greater the weight that measure is given when considered 
in combination with practicability to determine the appropriateness of 
the mitigation measure, and vice versa. We discuss consideration of 
these factors in greater detail below.

1. Reduction of Adverse Impacts to Marine Mammal Species or Stocks and 
Their Habitat 4
---------------------------------------------------------------------------

    \4\ We recognize the least practicable adverse impact standard 
requires consideration of measures that will address minimizing 
impacts on the availability of the species or stocks for subsistence 
uses where relevant. Because subsistence uses are not implicated for 
this action we do not discuss them. However, a similar framework 
would apply for evaluating those measures, taking into account the 
MMPA's directive that we make a finding of no unmitigable adverse 
impact on the availability of the species or stocks for taking for 
subsistence, and the relevant implementing regulations.
---------------------------------------------------------------------------

    The emphasis given to a measure's ability to reduce the impacts on 
a species or stock considers the degree, likelihood, and context of the 
anticipated reduction of impacts to individuals as well as the status 
of the species or stock.
    The ultimate impact on any individual from a disturbance event 
(which informs the likelihood of adverse species- or stock-level 
effects) is dependent on the circumstances and associated contextual 
factors, such as duration of exposure to stressors. Though any required 
mitigation needs to be evaluated in the context of the specific 
activity and the species or stocks affected, measures with the 
following types of goals are expected to reduce the likelihood or 
severity of adverse species- or stock-level impacts: Avoiding or 
minimizing injury or mortality; limiting interruption of known feeding, 
breeding, mother/calf, or resting behaviors; minimizing the abandonment 
of important habitat (temporally and spatially); minimizing the number 
of individuals subjected to these types of disruptions; and limiting 
degradation of habitat. Mitigating these types of effects is intended 
to reduce the likelihood that the activity will result in energetic or 
other types of impacts that are more likely to result in reduced 
reproductive success or survivorship. It is also important to consider 
the degree of impacts that are expected in the absence of mitigation in 
order to assess the added value of any potential measures. Finally, 
because the least practicable adverse impact standard gives NMFS the 
discretion to weigh a variety of factors when determining what should 
be included as appropriate mitigation measures and because the focus is 
on reducing impacts at the species or stock level, it does not compel 
mitigation for every kind of individual take, even when practicable for 
implementation by the applicant.
    The status of the species or stock is also relevant in evaluating 
the appropriateness of potential mitigation measures in the context of 
least practicable adverse impact. The following are examples of factors 
that may (either alone, or in combination) result in greater emphasis 
on the importance of a mitigation measure in reducing impacts on a 
species or stock: The stock is known to be decreasing or status is 
unknown, but believed to be declining; the known annual mortality (from 
any source) is approaching or exceeding the PBR level; the affected 
species or stock is a small, resident population; or the stock is 
involved in a UME or has other known vulnerabilities.
    Habitat mitigation, particularly as it relates to rookeries, mating 
grounds, and areas of similar significance, is also relevant to 
achieving the standard and can include measures such as reducing 
impacts of the activity on known prey utilized in the activity area or 
reducing impacts on physical habitat. As with species- or stock-related 
mitigation, the emphasis given to a measure's ability to reduce impacts 
on a species or stock's habitat considers the degree, likelihood, and 
context of the anticipated reduction of impacts to habitat. Because 
habitat value is informed by marine mammal presence and use, in some 
cases there may be overlap in measures for the species or stock and for 
use of habitat.
    We consider available information indicating the likelihood of any 
measure to accomplish its objective. If evidence shows that a measure 
has not typically been effective or successful, then either that 
measure should be modified or the potential value of the measure to 
reduce effects is lowered.

2. Practicability

    Factors considered may include those such as cost, impact on 
operations, personnel safety, and practicality of implementation.
    In carrying out the MMPA's mandate for these five IHAs, we apply 
the previously described context-specific balance between the manner in 
which and the degree to which measures are expected to reduce impacts 
to the affected species or stocks and their habitat and practicability 
for the applicant. The effects of concern (i.e., those with the 
potential to adversely impact species or stocks and their habitat), 
addressed previously in the ``Potential Effects of the Specified 
Activity on Marine Mammals and Their Habitat'' section, include 
auditory injury, severe behavioral reactions, disruptions of critical 
behaviors, and to a lesser degree, masking and impacts on acoustic 
habitat (see discussion of this concept in the ``Anticipated Effects on 
Marine Mammal Habitat'' section in the Notice of Proposed IHAs). Here, 
we focus on measures with proven or reasonably presumed ability to 
avoid or reduce the intensity of acute exposures that have potential to 
result in these anticipated effects with an understanding of the 
drawbacks or costs of these requirements, as well as time-area 
restrictions that would avoid or reduce both acute and chronic impacts. 
To the extent of the information available to us, we considered 
practicability concerns, as well as potential undesired consequences of 
the measures, e.g., extended periods using the acoustic source due to 
the need to reshoot lines. We also recognize that instantaneous 
protocols, such as shutdown requirements, are not capable of avoiding 
all acute effects, and are not suitable for avoiding many cumulative or 
chronic effects and do not provide targeted protection in areas of 
greatest importance for marine mammals. Therefore, in addition to a 
basic suite of seismic mitigation protocols, we also consider measures 
that may or may not be appropriate for other activities (e.g., time-
area restrictions specific to the surveys discussed herein) but that 
are warranted here given the spatial scope of these specified 
activities, potential for population-level effects and/or high 
magnitude of take for certain species in the absence of such mitigation 
(see ``Negligible Impact Analyses and

[[Page 63344]]

Determinations''), and the information we have regarding habitat for 
certain species.
    In order to satisfy the MMPA's least practicable adverse impact 
standard, we evaluated a suite of basic mitigation protocols that are 
required regardless of the status of a stock. Additional or enhanced 
protections are required for species whose stocks are in poor health 
and/or are subject to some significant additional stressor that lessens 
that stock's ability to weather the effects of the specified activities 
without worsening its status. We reviewed the applicants' proposals, 
the requirements specified in BOEM's PEIS, seismic mitigation protocols 
required or recommended elsewhere (e.g., HESS, 1999; DOC, 2013; IBAMA, 
2005; Kyhn et al., 2011; JNCC, 2017; DEWHA, 2008; BOEM, 2016a; DFO, 
2008; GHFS, 2015; MMOA, 2015; Nowacek et al., 2013; Nowacek and 
Southall, 2016), and the available scientific literature. We also 
considered recommendations given in a number of review articles (e.g., 
Weir and Dolman, 2007; Compton et al., 2008; Parsons et al., 2009; 
Wright and Cosentino, 2015; Stone, 2015b). Certain changes from the 
mitigation measures described in our Notice of Proposed IHAs were made 
on the basis of additional information and following review of public 
comments. The required suite of mitigation measures differs in some 
cases from the measures proposed by the applicants and/or those 
specified by BOEM in their PEIS and Record of Decision (ROD) in order 
to reflect what we believe to be the most appropriate suite of measures 
to satisfy the requirements of the MMPA.
    First, we summarize notable changes made to the mitigation 
requirements as a result of review of public comments and then describe 
mitigation prescribed in the issued IHAs. For additional detail 
regarding mitigation considerations, including expected efficacy and/or 
practicability, or descriptions of mitigation considered but not 
required, please see our Notice of Proposed IHAs.
    Here we provide a single description of required mitigation 
measures, as we require the same measures of all applicants.
Changes From the Notice of Proposed IHAs
    Here we summarize substantive changes to mitigation requirements 
from our Notice of Proposed IHAs. All changes were made on the basis of 
review of public comments received, including from applicants, and/or 
review of new information.
Time-Area Restrictions
     We spatially expanded the proposed time-area restriction 
for North Atlantic right whales. Our proposed restriction area was 
comprised of an area containing three distinct areas: (1) A 20-nmi 
coastal strip throughout the specific geographic region; (2) designated 
Seasonal Management Areas; and (3) designated critical habitat. This 
combined area was then buffered by 10 km, resulting in an approximate 
47-km standoff distance. We received numerous public comments 
expressing concern regarding the adequacy of this measure and, more 
generally, regarding the status of the North Atlantic right whale. 
Also, since publication of the Notice of Proposed IHAs, the status of 
this population has worsened, including declaration of an ongoing UME. 
Given this, we considered newly available information (e.g., Roberts et 
al., 2017; Davis et al., 2017) and re-evaluated the restriction. This 
is described in more detail under ``Comments and Responses'' as well as 
later in this section. Following this review, we expanded the 
restriction to 80 km from shore, with the same 10-km buffer, for a 
total 90-km restriction. As was proposed, the restriction would be in 
effect from November through April.
    However, in lieu of this requirement, applicants may alternatively 
develop and submit a monitoring and mitigation plan for NMFS's approval 
that would be sufficient to achieve comparable protection for North 
Atlantic right whales. If approved, applicants would be required to 
maintain a minimum coastal standoff distance of 47 km from November 
through April while operating in adherence with the approved plan from 
47 through 80 km offshore. (Note that the 80 km distance is assumed to 
represent to a reasonable extent right whale occurrence on the 
migratory pathway; therefore, under an approved plan the 10-km buffer 
would not be relevant.)
     We shifted the timing of the ``Hatteras and North'' time-
area restriction (Area #4 in Figure 4 and Table 7; described as Area #5 
in our Notice of Proposed IHAs), developed primarily to benefit beaked 
whales, sperm whales, and pilot whales, but also to provide seasonal 
protection to a notable biodiversity hotspot. The timing of this 
restriction, proposed as July through September (Roberts et al., 
2015n), is shifted to January through March on the basis of new 
information (Stanistreet et al., 2018), as described in more detail 
later in this section. The restriction area remains the same.
     We eliminated the proposed (former) Area #1, which was 
delineated in an effort to reduce likely acoustic exposures for the 
species for three applicants only, as opposed to a more meaningful 
reduction of impacts in important habitat and/or for species expected 
to be more sensitive to disturbance from airgun noise. As was stated in 
our Notice of Proposed IHAs, ``Although there are no relevant 
considerations with regard to population context or specific stressors 
that lead us to develop mitigation focused on Atlantic spotted dolphins 
[ . . . ] we believe it appropriate to delineate a time-area 
restriction for the sole purpose of reducing likely acoustic exposures 
for the species [for three companies].'' We received comments on this 
proposed restriction from several commenters who provided compelling 
rationale to eliminate the measure. As was stated in our Notice of 
Proposed IHAs, Atlantic spotted dolphins display a bifurcated 
distribution, with a portion of the stock inhabiting the continental 
shelf south of Cape Hatteras inside the 200-m isobath and a portion of 
the stock off the shelf and north of the Gulf Stream (north of Cape 
Hatteras). Our proposed restriction--located in the southern, on-shelf 
portion of the range, which we believe to be more predictable habitat 
for the species--was not likely to have the intended effect, as a 
seasonal restriction would not necessarily reduce acoustic exposures 
for a species that is not known to migrate in and out of the 
restriction area, and because a relatively small portion of overall 
survey effort was planned for this area. Implementation of this 
restriction would also likely have meaningful practicability 
implications for applicants with survey lines in the area, as they 
would need to plan for both the seasonal restriction for spotted 
dolphin (proposed as July through September) as well as the right whale 
restriction, which overlaps the proposed spotted dolphin area and would 
be in effect from November through April. Therefore, the proposal would 
not likely provide commensurate benefit to the species to offset these 
concerns.
Shutdown Requirements
     In our Notice of Proposed IHAs, we proposed an exception 
to the general shutdown requirements for certain species of dolphins in 
certain circumstances. Specifically, we proposed that the exception to 
the shutdown requirement would apply if the animals are traveling, 
including approaching the vessel. Our rationale in proposing this 
specific exception was to avoid the perceived subjective decision-

[[Page 63345]]

making associated with an exception based on a determination that 
dolphins were approaching voluntarily, while still protecting dolphins 
from disturbance of potentially important behaviors such as feeding or 
socialization, as might be indicated by the presence of dolphins 
engaged in behavior other than traveling (e.g., milling). Although the 
``bow-riding'' dolphin exception was similarly criticized when 
presented for public comment in BOEM's draft PEIS, we agree that our 
proposal (i.e., based on ``traveling'' versus ``stationary'' dolphins 
in relation to the vessel's movement) was unclear and that it would not 
likely result in an improvement with regard to clarity of protected 
species observer (PSO) decision-making. Therefore, this proposal was 
properly considered impracticable, while not offering meaningfully 
commensurate biological benefit. While we are careful to note that we 
do not fully understand the reasons for and potential effects of 
dolphin interaction with vessels, including working survey vessels, we 
also understand that dolphins are unlikely to incur any degree of 
threshold shift due to their relative lack of sensitivity to the 
frequency content in an airgun signal (as well as because of potential 
coping mechanisms). We also recognize that, although dolphins do in 
fact react to airgun noise in ways that may be considered take 
(Barkaszi et al., 2012), there is a lack of notable adverse dolphin 
reactions to airgun noise despite a large body of observational data. 
Therefore, the removal of the conditional shutdown measure for small 
delphinids is warranted in consideration of the available information 
regarding the effectiveness of such measures in mitigating impacts to 
small delphinids and the practicability of such measures. No shutdown 
is required for these species.
     We proposed a number of expanded shutdown requirements on 
the basis of detections of certain species deemed particularly 
sensitive (e.g., beaked whales) or of particular circumstances deemed 
to warrant the expanded shutdown requirement (e.g., whales with 
calves). These were all conditioned upon observation or detection of 
these species or circumstances at any distance from the vessel. We 
received several comments challenging the value of expanded shutdown 
requirements at all and, while we disagree with these comments, we 
agree that some reasonable distance limit should be placed on these 
requirements in order to better focus the observational effort of PSOs 
and to avoid the potential for numerous shutdowns based on uncertain 
detections at great distance. Therefore, as described in greater detail 
later in this section, we limit such expanded shutdown zones for 
relevant species or circumstances to 1.5 km.
     We eliminated a proposed requirement for shutdowns upon 
observation of a diving sperm whale at any distance centered on the 
forward track of the source vessel. We received several comments 
indicating that this proposed requirement was unclear in terms of how 
it was to be implemented, and that the benefit to the species was 
poorly demonstrated. We agree with these comments.
     We eliminated a proposed requirement for shutdowns upon 
detection of fin whales at any distance (proposed for TGS only). As 
stated in our Notice of Proposed IHAs, this requirement was proposed 
only on the basis of a high predicted amount of exposures. Following 
review of this requirement, we recognize that it would not be effective 
in achieving the stated goal of reducing the overall amount of takes, 
as any observed fin whale would still be within the Level B harassment 
zone and thus taken. Therefore, this measure serves no meaningful 
purpose while imposing an additional practicability burden on TGS.
     We clarify that the proposed requirement to shut down upon 
observation of an aggregation of marine mammals applies only to large 
whales (i.e., baleen whales and sperm whales), as was our intent. 
Several commenters interpreted the requirement as applying to all 
marine mammals and noted that this would require a significant increase 
in shutdowns as a result of the prevalence of observations of dolphins 
in groups exceeding five (most dolphin species have average group sizes 
larger than five). It has been common practice in prior issued IHAs for 
similar activities to require such a measure for whale species; 
however, we inadvertently omitted this key detail in describing the 
proposed measure. Also, we remove the language regarding ``traveling,'' 
which had been proposed in a similar context as was discussed above for 
small delphinids and which we have determined to be a poorly defined 
condition.
Monitoring
     We require that at least two acoustic PSOs have prior 
experience (minimum 90 days) working in that role, on the basis of 
discussion with experts who emphasized the critical importance of 
experience for acoustic PSOs (e.g., Thode et al., 2017; pers. comm., D. 
Epperson, BSEE). Our proposal required that only one acoustic PSO have 
prior experience.
    Below, we describe mitigation requirements in detail.
Mitigation-Related Monitoring
    Monitoring by independent, dedicated, trained marine mammal 
observers is required. Note that, although we discuss requirements 
related only to observation of marine mammals, we hereafter use the 
generic term ``protected species observer'' (PSO). Independent 
observers are employed by a third-party observer provider; vessel crew 
may not serve as PSOs. Dedicated observers are those who have no tasks 
other than to conduct observational effort, record observational data, 
and communicate with and instruct the survey operator (i.e., vessel 
captain and crew) with regard to the presence of marine mammals and 
mitigation requirements. Communication with the operator may include 
brief alerts regarding maritime hazards. Trained PSOs have successfully 
completed an approved PSO training course (see ``Monitoring and 
Reporting''), and experienced PSOs have additionally gained a minimum 
of 90 days at-sea experience working as a PSO during a deep penetration 
seismic survey, with no more than 18 months having elapsed since the 
conclusion of the relevant at-sea experience. Training and experience 
is specific to either visual or acoustic PSO duties. An experienced 
visual PSO must have completed approved, relevant training and must 
have gained the requisite experience working as a visual PSO. An 
experienced acoustic PSO must have completed a passive acoustic 
monitoring (PAM) operator training course and must have gained the 
requisite experience working as an acoustic PSO. Hereafter, we also 
refer to acoustic PSOs as PAM operators.
    NMFS expects to provide informal approval for specific training 
courses as needed to approve PSO staffing plans. NMFS does not plan to 
formally administer any training program or to sanction any specific 
provider, but will approve courses that meet the curriculum and trainer 
requirements specified herein (see ``Monitoring and Reporting''). We 
expect to provide such approvals in context of the need to ensure that 
PSOs have the necessary training to carry out their duties competently 
while also approving applicant staffing plans quickly. In order for 
PSOs to be approved, NMFS must review and approve PSO resumes 
accompanied by a relevant training course information packet that 
includes

[[Page 63346]]

the name and qualifications (i.e., experience, training completed, or 
educational background) of the instructor(s), the course outline or 
syllabus, and course reference material as well as a document stating 
the PSO's successful completion of the course. Although NMFS must 
affirm PSO approvals, third-party observer providers and/or companies 
seeking PSO staffing should expect that observers having satisfactorily 
completed approved training and with the requisite experience (if 
required) will be quickly approved. A PSO may be trained and/or 
experienced as both a visual PSO and PAM operator and may perform 
either duty, pursuant to scheduling requirements. PSO watch schedules 
shall be devised in consideration of the following restrictions: (1) A 
maximum of two consecutive hours on watch followed by a break of at 
least one hour between watches for visual PSOs (periods typical of 
observation for research purposes and as used for airgun surveys in 
certain circumstances (Broker et al., 2015)); (2) a maximum of four 
consecutive hours on watch followed by a break of at least two 
consecutive hours between watches for PAM operators; and (3) a maximum 
of 12 hours observation per 24-hour period. Further information 
regarding PSO requirements may be found in the ``Monitoring and 
Reporting'' section, later in this document.
    During survey operations (e.g., any day on which use of the 
acoustic source is planned to occur; whenever the acoustic source is in 
the water, whether activated or not), a minimum of two PSOs must be on 
duty and conducting visual observations at all times during daylight 
hours (i.e., from 30 minutes prior to sunrise through 30 minutes 
following sunset) and 30 minutes prior to and during nighttime ramp-ups 
of the airgun array (see ``Ramp-ups'' below). PSOs should use NOAA's 
solar calculator (www.esrl.noaa.gov/gmd/grad/solcalc/) to determine 
sunrise and sunset times at their specific location. We recognize that 
certain daytime conditions (e.g., fog, heavy rain) may reduce or 
eliminate effectiveness of visual observations; however, on-duty PSOs 
shall remain alert for marine mammal observational cues and/or a change 
in conditions.
    All source vessels must carry a minimum of one experienced visual 
PSO, who shall be designated as the lead PSO, coordinate duty schedules 
and roles, and serve as primary point of contact for the operator. 
However, while it is desirable for all PSOs to be qualified through 
experience, we are also mindful of the need to expand the workforce by 
allowing opportunity for newly trained PSOs to gain experience. 
Therefore, the lead PSO shall devise the duty schedule such that 
experienced PSOs are on duty with trained PSOs (i.e., those PSOs with 
appropriate training but who have not yet gained relevant experience) 
to the maximum extent practicable in order to provide necessary 
mentorship.
    With regard to specific observational protocols, we largely follow 
those described in Appendix C of BOEM's PEIS (BOEM, 2014a). The lead 
PSO shall determine the most appropriate observation posts that will 
not interfere with navigation or operation of the vessel while 
affording an optimal, elevated view of the sea surface; these should be 
the highest elevation available on each vessel, with the maximum 
viewable range from the bow to 90 degrees to port or starboard of the 
vessel. PSOs shall coordinate to ensure 360[deg] visual coverage around 
the vessel, and shall conduct visual observations using binoculars and 
the naked eye while free from distractions and in a consistent, 
systematic, and diligent manner. All source vessels must be equipped 
with pedestal-mounted ``bigeye'' binoculars that will be available for 
PSO use. Within these broad outlines, the lead PSO and PSO team will 
have discretion to determine the most appropriate vessel- and survey-
specific system for implementing effective marine mammal observational 
effort. Any observations of marine mammals by crew members aboard any 
vessel associated with the survey, including chase vessels, should be 
relayed to the source vessel and to the PSO team.
    All source vessels must use a towed PAM system for potential 
detection of marine mammals. The system must be monitored at all times 
during use of the acoustic source, and acoustic monitoring must begin 
at least 30 minutes prior to ramp-up. PAM operators must be 
independent, and all source vessels shall carry a minimum of two 
experienced PAM operators. PAM operators shall communicate all 
detections to visual PSOs, when visual PSOs are on duty, including any 
determination by the PSO regarding species identification, distance and 
bearing and the degree of confidence in the determination. Further 
detail regarding PAM system requirements may be found in the 
``Monitoring and Reporting'' section, later in this document. The 
effectiveness of PAM depends to a certain extent on the equipment and 
methods used and competency of the PAM operator, but no established 
standards are currently in place.
    Visual monitoring must begin at least 30 minutes prior to ramp-up 
(described below) and must continue until one hour after use of the 
acoustic source ceases or until 30 minutes past sunset. If any marine 
mammal is observed at any distance from the vessel, a PSO would record 
the observation and monitor the animal's position (including latitude/
longitude of the vessel and relative bearing and estimated distance to 
the animal) until the animal dives or moves out of visual range of the 
observer. A PSO would continue to observe the area to watch for the 
animal to resurface or for additional animals that may surface in the 
area. Visual PSOs shall communicate all observations to PAM operators, 
including any determination by the PSO regarding species 
identification, distance, and bearing and the degree of confidence in 
the determination.
    As noted previously, all source vessels must carry a minimum of one 
experienced visual PSO and two experienced PAM operators. The observer 
designated as lead PSO (including the full team of visual PSOs and PAM 
operators) must have experience as a visual PSO. The applicant may 
determine how many additional PSOs are required to adequately fulfill 
the requirements specified here. To summarize, these requirements are: 
(1) 24-hour acoustic monitoring during use of the acoustic source; (2) 
visual monitoring during use of the acoustic source by two PSOs during 
all daylight hours, with one visual PSO on-duty during nighttime ramp-
ups; (3) maximum of two consecutive hours on watch followed by a 
minimum of one hour off watch for visual PSOs and a maximum of four 
consecutive hours on watch followed by a minimum of two consecutive 
hours off watch for PAM operators; and (4) maximum of 12 hours of 
observational effort per 24-hour period for any PSO, regardless of 
duties.
    PAM Malfunction--Emulating sensible protocols described by the New 
Zealand Department of Conservation for airgun surveys conducted in New 
Zealand waters (DOC, 2013), survey activity may continue for brief 
periods of time when the PAM system malfunctions or is damaged. 
Activity may continue for 30 minutes without PAM while the PAM operator 
diagnoses the issue. If the diagnosis indicates that the PAM system 
must be repaired to solve the problem, operations may continue for an 
additional two hours without acoustic monitoring under the following 
conditions:

[[Page 63347]]

     Daylight hours and sea state is less than or equal to 
Beaufort sea state (BSS) 4;
     No marine mammals (excluding delphinids; see below) 
detected solely by PAM in the exclusion zone (see below) in the 
previous two hours;
     NMFS is notified via email as soon as practicable with the 
time and location in which operations began without an active PAM 
system; and
     Operations with an active acoustic source, but without an 
operating PAM system, do not exceed a cumulative total of four hours in 
any 24-hour period.
Exclusion Zone and Buffer Zone
    An exclusion zone is a defined area within which occurrence of a 
marine mammal triggers mitigation action intended to reduce potential 
for certain outcomes, e.g., auditory injury, more severe disruption of 
behavioral patterns. The PSOs shall establish and monitor a 500-m 
exclusion zone and additional 500-m buffer zone (total 1,000 m) during 
the pre-clearance period (see below) and a 500-m exclusion zone during 
the ramp-up and operational periods. PSOs should focus their 
observational effort within this 1-km zone, although animals observed 
at greater distances should be recorded and mitigation action taken as 
necessary (see below). These zones shall be based upon radial distance 
from any element of the airgun array (rather than being based on the 
center of the array or around the vessel itself). During use of the 
acoustic source, occurrence of marine mammals within the buffer zone 
(but outside the exclusion zone) should be communicated to the operator 
to prepare for the potential shutdown of the acoustic source. Use of 
the buffer zone in relation to ramp-up is discussed below under ``Ramp-
up.'' Further detail regarding the exclusion zone and shutdown 
requirements is given under ``Exclusion Zone and Shutdown 
Requirements.''
Ramp-Up
    Ramp-up of an acoustic source is intended to provide a gradual 
increase in sound levels, enabling animals to move away from the source 
if the signal is sufficiently aversive prior to its reaching full 
intensity. We infer on the basis of behavioral avoidance studies and 
observations that this measure results in some reduced potential for 
auditory injury and/or more severe behavioral reactions. Although this 
measure is not proven and some arguments have been made that use of 
ramp-up may not have the desired effect of aversion (which is itself a 
potentially negative impact but assumed to be better than the 
alternative), ramp-up remains a relatively low-cost, common-sense 
component of standard mitigation for airgun surveys. Ramp-up is most 
likely to be effective for more sensitive species (e.g., beaked whales) 
with known behavioral responses at greater distances from an acoustic 
source (e.g., Tyack et al., 2011; DeRuiter et al., 2013; Miller et al., 
2015).
    The ramp-up procedure involves a step-wise increase in the number 
of airguns firing and total array volume until all operational airguns 
are activated and the full volume is achieved. Ramp-up is required at 
all times as part of the activation of the acoustic source (including 
source tests; see ``Miscellaneous Protocols'' for more detail) and may 
occur at times of poor visibility, assuming appropriate acoustic 
monitoring with no detections in the 30 minutes prior to beginning 
ramp-up. Acoustic source activation should only occur at night where 
operational planning cannot reasonably avoid such circumstances. For 
example, a nighttime initial ramp-up following port departure is 
reasonably avoidable and may not occur. Ramp-up may occur at night 
following acoustic source deactivation due to line turn or mechanical 
difficulty. The operator must notify a designated PSO of the planned 
start of ramp-up as agreed-upon with the lead PSO; the notification 
time should be at least 60 minutes prior to the planned ramp-up. A 
designated PSO must be notified again immediately prior to initiating 
ramp-up procedures and the operator must receive confirmation from the 
PSO to proceed.
    Ramp-up procedures follow the recommendations of IAGC (2015). Ramp-
up would begin by activating a single airgun (i.e., array element) of 
the smallest volume in the array. Ramp-up continues in stages by 
doubling the number of active elements at the commencement of each 
stage, with each stage of approximately the same duration. Total 
duration should not be less than approximately 20 minutes but maximum 
duration is not prescribed and will vary depending on the total number 
of stages. Von Benda-Beckmann et al. (2013), in a study of the 
effectiveness of ramp-up for sonar, found that extending the duration 
of ramp-up did not have a corresponding effect on mitigation benefit. 
There will generally be one stage in which doubling the number of 
elements is not possible because the total number is not even. This 
should be the last stage of the ramp-up sequence. The operator must 
provide information to the PSO documenting that appropriate procedures 
were followed. Ramp-ups should be scheduled so as to minimize the time 
spent with the source activated prior to reaching the designated run-
in. This approach is intended to ensure a perceptible increase in sound 
output per increment while employing increments that produce similar 
degrees of increase at each step.
    PSOs must monitor a 1,000-m zone (or to the distance visible if 
less than 1,000 m) for a minimum of 30 minutes prior to ramp-up (i.e., 
pre-clearance). The pre-clearance period may occur during any vessel 
activity (i.e., transit, line turn). Ramp-up must be planned to occur 
during periods of good visibility when possible; operators may not 
target the period just after visual PSOs have gone off duty. Following 
deactivation of the source for reasons other than mitigation, the 
operator must communicate the near-term operational plan to the lead 
PSO with justification for any planned nighttime ramp-up. Any suspected 
patterns of abuse must be reported by the lead PSO to be investigated 
by NMFS. Ramp-up may not be initiated if any marine mammal is within 
the designated 1,000-m zone. If a marine mammal is observed within the 
zone during the pre-clearance period, ramp-up may not begin until the 
animal(s) has been observed exiting the zone or until an additional 
time period has elapsed with no further sightings (i.e., 15 minutes for 
small odontocetes and 30 minutes for all other species). PSOs will 
monitor the 500-m exclusion zone during ramp-up, and ramp-up must cease 
and the source shut down upon observation of marine mammals within or 
approaching the zone.
Exclusion Zone and Shutdown Requirements
    The PSOs must establish a minimum exclusion zone with a 500-m 
radius as a perimeter around the outer extent of the airgun array 
(rather than being delineated around the center of the array or the 
vessel itself). If a marine mammal (other than the small delphinid 
species discussed below) appears within or enters this zone, the 
acoustic source must be shut down (i.e., power to the acoustic source 
must be immediately turned off). If a marine mammal is detected 
acoustically, the acoustic source must be shut down, unless the PAM 
operator is confident that the animal detected is outside the exclusion 
zone or that the detected species is not subject to the shutdown 
requirement (see below).
    The 500-m radial distance of the standard exclusion zone is 
expected to contain sound levels exceeding peak pressure injury 
criteria for all hearing groups other than, potentially, high-frequency 
cetaceans, while also

[[Page 63348]]

providing a consistent, reasonably observable zone within which PSOs 
would typically be able to conduct effective observational effort. 
Although significantly greater distances may be observed from an 
elevated platform under good conditions, we believe that 500 m is 
likely regularly attainable for PSOs using the naked eye during typical 
conditions. In addition, an exclusion zone is expected to be helpful in 
avoiding more severe behavioral responses. Behavioral response to an 
acoustic stimulus is determined not only by received level but by 
context (e.g., activity state) including, importantly, proximity to the 
source (e.g., Southall et al., 2007; Ellison et al., 2012; DeRuiter et 
al., 2013). In prescribing an exclusion zone, we seek not only to avoid 
most potential auditory injury but also to reduce the likely severity 
of the behavioral response at a given received level of sound.
    As discussed in our Notice of Proposed IHAs, use of monitoring and 
shutdown measures within defined exclusion zone distances is inherently 
an essentially instantaneous proposition--a rule or set of rules that 
requires mitigation action upon detection of an animal. This indicates 
that defining an exclusion zone on the basis of cSEL thresholds, which 
require that an animal accumulate some level of sound energy exposure 
over some period of time (e.g., 24 hours), has questionable relevance 
as a standard protocol for mobile sources, given the relative motion of 
the source and the animals. A PSO aboard a mobile source will typically 
have no ability to monitor an animal's position relative to the 
acoustic source over relevant time periods for purposes of 
understanding whether auditory injury is likely to occur on the basis 
of cumulative sound exposure and, therefore, whether action should be 
taken to avoid such potential.
    Cumulative SEL thresholds are more relevant for purposes of 
modeling the potential for auditory injury than they are for dictating 
real-time mitigation, though they can be informative (especially in a 
relative sense). We recognize the importance of the accumulation of 
sound energy to an understanding of the potential for auditory injury 
and that it is likely that, at least for low-frequency cetaceans, some 
potential auditory injury is likely impossible to fully avoid and 
should be considered for authorization.
    Considering both the dual-metric thresholds described previously 
(and shown in Table 3) and hearing group-specific marine mammal 
auditory weighting functions in the context of the airgun sources 
considered here, auditory injury zones indicated by the peak pressure 
metric are expected to be predominant for both mid- and high-frequency 
cetaceans, while zones indicated by cSEL criteria are expected to be 
predominant for low-frequency cetaceans. Assuming source levels 
provided by the applicants and indicated in Table 1 and spherical 
spreading propagation, distances for exceedance of group-specific peak 
injury thresholds were calculated and are shown in Table 5.
    Consideration of auditory injury zones based on cSEL criteria are 
dependent on the animal's generalized hearing range and how that 
overlaps with the frequencies produced by the sound source of interest 
in relation to marine mammal auditory weighting functions (NMFS, 2018). 
As noted above, these are expected to be predominant for low-frequency 
cetaceans because their most susceptible hearing range overlaps the low 
frequencies produced by airguns, while the modeling indicates that 
zones based on peak pressure criteria dominate for mid- and high-
frequency cetaceans. As described in detail in our Notice of Proposed 
IHAs, we obtained unweighted spectrum data (modeled in 1 Hz bands) for 
a reasonably equivalent acoustic source (i.e., a 36-airgun array with 
total volume of 6,600 in\3\) in order to evaluate notional zone sizes 
and to incorporate NMFS's technical guidance weighting functions over 
an airgun array's full acoustic band. Using NMFS's associated User 
Spreadsheet with hearing group-specific weighted source levels, and 
inputs assuming spherical spreading propagation, a source velocity of 
4.5 kn, shot intervals specified by the applicants, and pulse duration 
of 100 ms, we calculated potential radial distances to auditory injury 
zones (shown in Table 5).
    Therefore, our 500-m exclusion zone contains the entirety of any 
potential injury zone for mid-frequency cetaceans (realistically, there 
is no such zone, as discussed above in ``Estimated Take''), while the 
zones within which injury could occur may be larger for high-frequency 
cetaceans (on the basis of peak pressure and depending on the specific 
array) and for low-frequency cetaceans (on the basis of cumulative 
sound exposure). Only three species of high-frequency cetacean could 
occur in the planned survey areas: The harbor porpoise and two species 
of the Family Kogiidae. Harbor porpoise are expected to occur rarely 
and only in the northern portion of the survey area. However, we 
require an extended shutdown measure for Kogia spp. to address these 
potential injury concerns (described later in this section).
    In summary, our goal in prescribing a standard exclusion zone 
distance is to (1) encompass zones for most species within which 
auditory injury could occur on the basis of instantaneous exposure; (2) 
provide 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) enable more 
effective implementation of required mitigation by providing 
consistency and ease of implementation for PSOs, who need to monitor 
and implement the exclusion zone; and (4) to define a distance within 
which detection probabilities are reasonably high for most species 
under typical conditions. Our use of 500 m as the zone is not based 
directly on any quantitative understanding of the range at which 
auditory injury would be entirely precluded or any range specifically 
related to disruption of behavioral patterns. Rather, we believe it is 
a reasonable combination of factors. This zone has been proven as a 
feasible measure through past implementation by operators in the Gulf 
of Mexico (GOM; as regulated by BOEM pursuant to the Outer Continental 
Shelf Lands Act (OCSLA) (43 U.S.C. 1331-1356)). In summary, a 
practicable criterion such as this has the advantage of familiarity and 
simplicity while still providing in most cases a zone larger than 
relevant auditory injury zones, given realistic movement of source and 
receiver. Increased shutdowns, without a firm idea of the outcome the 
measure seeks to avoid, simply displace survey activity in time and 
increase the total duration of acoustic influence as well as total 
sound energy in the water (due to additional ramp-up and overlap where 
data acquisition was interrupted).
    Dolphin Exception--The shutdown requirement described above is in 
place for all marine mammals, with the exception of small delphinids. 
As defined here, the small delphinid group is intended to encompass 
those members of the Family Delphinidae most likely to voluntarily 
approach the source vessel for purposes of interacting with the vessel 
and/or airgun array (e.g., bow-riding). This exception to the shutdown 
requirement applies solely to specific genera of small dolphins--Steno, 
Tursiops, Stenella, Delphinus, Lagenorhynchus, and Lagenodelphis (see 
Table 2)--and applies under all circumstances, regardless of what the 
perception of the animal(s) behavior or intent may be. Variations of 
this measure that include exceptions based on animal behavior--
including that

[[Page 63349]]

described in our Notice of Proposed IHAs, in which an exception was 
proposed to be applied only to ``traveling'' dolphins--have been 
proposed by both NMFS and BOEM and have been criticized, in part due to 
the subjective on-the-spot decision-making this scheme would require of 
PSOs. If the mitigation requirements are not sufficiently clear and 
objective, the outcome may be differential implementation across 
surveys as informed by individual PSOs' experience, background, and/or 
training. The exception described here is based on several factors: The 
lack of evidence of or presumed potential for the types of effects to 
these species of small delphinid that our shutdown requirement for 
other species seeks to avoid, the uncertainty and subjectivity 
introduced by such a decision framework, and the practicability concern 
presented by the operational impacts. Despite a large volume of 
observational effort during airgun surveys, including in locations 
where dolphin shutdowns have not previously been required (i.e., the 
U.S. GOM and United Kingdom (UK) waters), we are not aware of accounts 
of notable adverse dolphin reactions to airgun noise (Stone, 2015a; 
Barkaszi et al., 2012) other than one isolated incident (Gray and Van 
Waerebeek, 2011). Dolphins have a relatively high threshold for the 
onset of auditory injury (i.e., PTS) and more severe adverse behavioral 
responses seem less likely given the evidence of purposeful approach 
and/or maintenance of proximity to vessels with operating airguns.
    The best available scientific evidence indicates that auditory 
injury as a result of airgun sources is extremely unlikely for mid-
frequency cetaceans, primarily due to a relative lack of sensitivity 
and susceptibility to noise-induced hearing loss at the frequency range 
output by airguns (i.e., most sound below 500 Hz) as shown by the mid-
frequency cetacean auditory weighting function (NMFS, 2018). Criteria 
for TTS in mid-frequency cetaceans for impulsive sounds were derived by 
experimental measurement of TTS in beluga whales exposed to pulses from 
a seismic watergun; dolphins exposed to the same stimuli in this study 
did not display TTS (Finneran et al., 2002). Moreover, when the 
experimental watergun signal was weighted appropriately for mid-
frequency cetaceans, less energy was filtered than would be the case 
for an airgun signal. More recently, Finneran et al. (2015) exposed 
bottlenose dolphins to repeated pulses from an airgun and measured no 
TTS.
    We caution that, while dolphins are observed voluntarily 
approaching source vessels (e.g., bow-riding or interacting with towed 
gear), the reasons for the behavior are unknown. In context of an 
active airgun array, the behavior cannot be assumed to be harmless. 
Although bow-riding comprises approximately 30 percent of behavioral 
observations in the GOM, there is a much lower incidence of the 
behavior when the acoustic source is active (Barkaszi et al., 2012), 
and this finding was replicated by Stone (2015a) for surveys occurring 
in UK waters. There appears to be evidence of aversive behavior by 
dolphins during firing of airguns. Barkaszi et al. (2012) found that 
the median closest distance of approach to the acoustic source was at 
significantly greater distances during times of full-power source 
operation when compared to silence, while Stone (2015a) and Stone and 
Tasker (2006) reported that behavioral responses, including avoidance 
and changes in swimming or surfacing behavior, were evident for 
dolphins during firing of large arrays. Goold and Fish (1998) described 
a ``general pattern of localized disturbance'' for dolphins in the 
vicinity of an airgun survey. However, while these general findings--
typically, dolphins will display increased distance from the acoustic 
source, decreased prevalence of ``bow-riding'' activities, and 
increases in surface-active behaviors--are indicative of adverse or 
aversive responses that may rise to the level of ``take'' (as defined 
by the MMPA), they are not indicative of any response of a severity 
such that the need to avoid it outweighs the impact on practicability 
for the industry and operators.
    Additionally, increased shutdowns resulting from such a measure 
would require source vessels 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. Therefore, 
the removal of such measures for small delphinids is warranted in 
consideration of the available information regarding the effectiveness 
of such measures in mitigating impacts to small delphinids and the 
practicability of such measures.
    Although other mid-frequency hearing specialists (e.g., large 
delphinids) are considered no more likely to incur auditory injury than 
are small delphinids, they are more typically deep divers, meaning that 
there is some increased potential for more severe effects from a 
behavioral reaction, as discussed in greater detail in ``Comments and 
Responses.'' Therefore, we anticipate benefit from a shutdown 
requirement for large delphinids in that it is likely to preclude more 
severe behavioral reactions for any such animals in close proximity to 
the source vessel as well as any potential for physiological effects.
    At the same time, large delphinids are much less likely to approach 
vessels. Therefore, a shutdown requirement for large delphinids would 
not have similar impacts as a small delphinid shutdown in terms of 
either practicability for the applicant or corollary increase in sound 
energy output and time on the water.
    Other Shutdown Requirements--Shutdown of the acoustic source is 
also required in the event of certain other observations beyond the 
standard 500-m exclusion zone. In our Notice of Proposed IHAs, we 
proposed to condition these shutdowns upon detection of the relevant 
species or circumstances at any distance. Following review of public 
comments, we determined it appropriate to limit such shutdown 
requirements to within a reasonable detection radius of 1.5 km. This 
maintains the intent of the measures as originally proposed, i.e., to 
provide for additional real-time protection by limiting the intensity 
and duration of acoustic exposures for certain species or in certain 
circumstances, while reducing the area over which PSOs must maintain 
observational effort. As for normal shutdowns within the standard 500-m 
exclusion zone, shutdowns at extended distance should be made on the 
basis of confirmed detections (visual or acoustic) within the zone.
    We determined an appropriate distance on the basis of available 
information regarding detection functions for relevant species, but 
note that, while based on quantitative data, the distance is an 
approximate limit that is merely intended to encompass the region 
within which we would expect a relatively high degree of success in 
sighting certain species while also improving PSO efficacy by removing 
the potential that a PSO might interpret these requirements as 
demanding a focus on areas further from the vessel. For each modeled 
taxon, Roberts et al. (2016) fitted detection functions that modeled 
the detectability of the taxon according to distance from the trackline 
and other covariates (i.e., the probability of detecting an animal 
given its distance from the transect). These functions were based on 
nearly 1.1 million linear km of line-transect survey effort conducted 
from 1992-2014, with surveys arranged in aerial and shipboard 
hierarchies and further grouped according to similarity

[[Page 63350]]

of observation protocol and platform. Where a taxon was sighted 
infrequently, a detection function was fit to pooled sightings of 
suitable proxy species. For example, for the North Atlantic right whale 
and shipboard binocular surveys (i.e., the relevant combination of 
platform and protocol), a detection function was fit using pooled 
sightings of right whales and other mysticete species (Roberts et al., 
2015p). The resulting detection function shows a slightly more than 20 
percent probability of detecting right whales at 2 km, with a mean 
effective strip half-width (ESHW) (which provides a measure of how far 
animals are seen from the transect line; Buckland et al., 2001) of 
1,309 m (Roberts et al., 2015p). Similarly, Barlow et al. (2011) 
reported mean ESHWs for various mysticete species ranging from 
approximately 1.5-2 km. The detection function used in modeling density 
for beaked whales provided a mean ESHW of 1,587 m (Roberts et al., 
2015l). Therefore, we set the shutdown radius for special circumstances 
(described below) at 1.5 km.
    Comments disagreeing with our proposal to require shutdowns upon 
certain detections at any distance also suggested that the measures did 
not have commensurate benefit for the relevant species. However, it 
must be noted that any such observations would still be within range of 
where behavioral disturbance of some form and degree would be likely to 
occur (Table 4). While visual PSOs should focus observational effort 
within the vicinity of the acoustic source and vessel, this does not 
preclude them from periodic scanning of the remainder of the visible 
area or from noting observations at greater distances, and there is no 
reason to believe that such periodic scans by professional PSOs would 
hamper the ability to maintain observation of areas closer to the 
source and vessel. Circumstances justifying shutdown at extended 
distance (i.e., within 1.5 km) include:
     Upon detection of a right whale. Recent data concerning 
the North Atlantic right whale, one of the most endangered whale 
species (Best et al., 2001), indicate uncertainty regarding the 
population's recovery and a possibility of decline (see discussion 
under ``Description of Marine Mammals in the Area of the Specified 
Activities''). We believe it appropriate to eliminate potential effects 
to individual right whales to the extent possible;
     Upon visual observation of a large whale (i.e., sperm 
whale or any baleen whale) with calf, with ``calf'' defined as an 
animal less than two-thirds the body size of an adult observed to be in 
close association with an adult. Groups of whales are likely to be more 
susceptible to disturbance when calves are present (e.g., Bauer et al., 
1993), and disturbance of cow-calf pairs could potentially result in 
separation of vulnerable calves from adults. Separation, if it 
occurred, could be exacerbated by airgun signals masking communication 
between adults and the separated calf (Videsen et al., 2017). Absent 
separation, airgun signals can disrupt or mask vocalizations essential 
to mother-calf interactions. Given the consequences of potential loss 
of calves in the context of ongoing UMEs for multiple mysticete 
species, as well as the functional sensitivity of the mysticete whales 
to frequencies associated with airgun survey activity, we believe this 
measure is warranted;
     Upon detection of a beaked whale or Kogia spp. These 
species are behaviorally sensitive deep divers and it is possible that 
disturbance could provoke a severe behavioral response leading to 
injury (e.g., Wursig et al., 1998; Cox et al., 2006). We recognize that 
there are generally low detection probabilities for beaked whales and 
Kogia spp., meaning that many animals of these species may go 
undetected. Barlow (1999) estimates such probabilities at 0.23 to 0.45 
for Cuvier's and Mesoplodont beaked whales, respectively. However, 
Barlow and Gisiner (2006) predict a roughly 24-48 percent reduction in 
the probability of detecting beaked whales during seismic mitigation 
monitoring efforts as compared with typical research survey efforts, 
and Moore and Barlow (2013) noted a decrease in g(0) for Cuvier's 
beaked whales from 0.23 at BSS 0 (calm) to 0.024 at BSS 5. Similar 
detection probabilities have been noted for Kogia spp., though they 
typically travel in smaller groups and are less vocal, thus making 
detection more difficult (Barlow and Forney, 2007). As discussed 
previously in this document (see ``Estimated Take''), there are high 
levels of predicted exposures for beaked whales in particular. 
Additionally for high-frequency cetaceans such as Kogia spp., auditory 
injury zones relative to peak pressure thresholds may range from 
approximately 350-1,550 m from the acoustic source, depending on the 
specific array characteristics (NMFS, 2018); and
     Upon visual observation of an aggregation (defined as six 
or more animals) of large whales of any species. Under these 
circumstances, we assume that the animals are engaged in some important 
behavior (e.g., feeding, socializing) that should not be disturbed.
    Shutdown Implementation Protocols--Any PSO on duty has the 
authority to delay the start of survey operations or to call for 
shutdown of the acoustic source. When shutdown is called for by a PSO, 
the acoustic source must be immediately deactivated and any dispute 
resolved only following deactivation. The operator must establish and 
maintain clear lines of communication directly between PSOs on duty and 
crew controlling the acoustic source to ensure that shutdown commands 
are conveyed swiftly while allowing PSOs to maintain watch; hand-held 
UHF radios are recommended. When both visual PSOs and PAM operators are 
on duty, all detections must be immediately communicated to the 
remainder of the on-duty team for potential verification of visual 
observations by the PAM operator or of acoustic detections by visual 
PSOs and initiation of dialogue as necessary. When there is certainty 
regarding the need for mitigation action on the basis of either visual 
or acoustic detection alone, the relevant PSO(s) must call for such 
action immediately.
    Upon implementation of shutdown, the source may be reactivated 
after the animal(s) has been observed exiting the exclusion zone or 
following a 30-minute clearance period with no further detection of the 
animal(s). For harbor porpoise--the only small odontocete for which 
shutdown is required--this clearance period is limited to 15 minutes.
    If the acoustic source is shut down for reasons other than 
mitigation (e.g., mechanical difficulty) for brief periods (i.e., less 
than 30 minutes), it may be activated again without ramp-up if PSOs 
have maintained constant visual and acoustic observation and no visual 
detections of any marine mammal have occurred within the exclusion zone 
and no acoustic detections have occurred. We define ``brief periods'' 
in keeping with other clearance watch periods and to avoid unnecessary 
complexity in protocols for PSOs. For any longer shutdown (e.g., during 
line turns), pre-clearance watch and ramp-up are required. For any 
shutdown at night or in periods of poor visibility (e.g., BSS 4 or 
greater), ramp-up is required but if the shutdown period was brief and 
constant observation maintained, pre-clearance watch is not required.
Power-Down
    Power-down, as defined here, refers to reducing the array to a 
single element as a substitute for full shutdown. Use of a single 
airgun as a ``mitigation source,''

[[Page 63351]]

e.g., during extended line turns, is not allowed. In a power-down 
scenario, it is assumed that reducing the size of the array to a single 
element reduces the ensonified area such that an observed animal is 
outside of any area within which injury or more severe behavioral 
reactions could occur. Here, power-down is not allowed for any reason 
(e.g., to avoid pre-clearance and/or ramp-up).
Miscellaneous Protocols
    The acoustic source must be deactivated when not acquiring data or 
preparing to acquire data, except as necessary for testing. Unnecessary 
use of the acoustic source should be avoided. Firing of the acoustic 
source at any volume above the stated production volume is not 
authorized for these IHAs; the operator must provide information to the 
lead PSO at regular intervals confirming the firing volume. Notified 
operational capacity (not including redundant backup airguns) must not 
be exceeded during the survey, except where unavoidable for source 
testing and calibration purposes. All occasions where activated source 
volume exceeds notified operational capacity must be noticed to the 
PSO(s) on duty and fully documented for reporting. The lead PSO must be 
granted access to relevant instrumentation documenting acoustic source 
power and/or operational volume.
    Testing of the acoustic source involving all elements requires 
normal mitigation protocols (e.g., ramp-up). Testing limited to 
individual source elements or strings does not require ramp-up but does 
require pre-clearance.
Restriction Areas
    Below we provide discussion of various time-area restrictions. 
Because the purpose of these areas is to reduce the likelihood of 
exposing animals within the designated areas to noise from airgun 
surveys that is likely to result in harassment, we require that source 
vessels maintain minimum standoff distances (i.e., buffers) from the 
areas. Sound propagation modeling results provided for a notional large 
airgun array in BOEM's PEIS indicate that a 10 km distance would likely 
contain received levels of sound exceeding 160 dB rms under a wide 
variety of conditions (e.g., 21 scenarios encompassing four depth 
regimes, four seasons, two bottom types). See Appendix D of BOEM's PEIS 
for more detail. The 95 percent ranges (i.e., the radius of a circle 
encompassing 95 percent of grid points equal to or greater than the 160 
dB threshold value) provided in Table D-22 of BOEM's PEIS range from 
4,959-9,122 m, with mean of 6,838 m. We adopt a standard 10-km buffer 
distance to avoid ensonification above 160 dB rms of restricted areas 
under most circumstances.
    Coastal Restriction--No survey effort may occur within 30 km of the 
coast. The intent of this restriction is to provide additional 
protection for coastal stocks of bottlenose dolphin, all of which are 
designated as depleted under the MMPA. This designation for all current 
coastal stocks is retained from the originally delineated single 
coastal migratory stock, which was revised to recognize the existence 
of multiple stocks in 2002 (Waring et al., 2016). The prior single 
coastal stock was designated as depleted because it was determined to 
be below the optimum sustainable population level (i.e., the number of 
animals that will result in the maximum productivity of the population, 
keeping in mind the carrying capacity of their ecosystem) (Waring et 
al., 2001). Already designated as depleted, a UME affected bottlenose 
dolphins along the Atlantic coast, from New York to Florida, from 2013-
15. Genetic analyses performed to date indicate that 99 percent of 
dolphins impacted were of the coastal ecotype, which may be expected to 
typically occur within 20 km of the coast. As described above, a 10 km 
buffer is provided to encompass the area within which sound exceeding 
160 dB rms would reasonably be expected to occur. Further discussion of 
this UME is provided under ``Description of Marine Mammals in the Area 
of the Specified Activity.''
    North Atlantic Right Whale--From November through April, no survey 
effort may occur within 90 km of the coast. In our Notice of Proposed 
IHAs, we proposed a similar restriction out to 47 km. The proposed 47-
km seasonal restriction of survey effort was intended to avoid 
ensonification by levels of sound expected to result in behavioral 
harassment of particular areas of expected importance for North 
Atlantic right whales, including designated critical habitat, vessel 
speed limit seasonal management areas (SMAs), a coastal strip 
containing SMAs, and vessel speed limit dynamic management areas 
(DMAs). This area was expected to provide substantial protection of 
right whales within the migratory corridor and calving and nursery 
grounds. However, following review of comments received from the Marine 
Mammal Commission, as well as other public comments received and as a 
result of the continued deterioration of the status of this population 
(described previously in ``Description of Marine Mammals in the Area of 
the Specified Activity''), we considered new information regarding 
predicted right whale distribution (e.g., Roberts et al., 2017; Davis 
et al., 2017) and re-evaluated the proposed right whale time-area 
restriction.
    Specifically, we became aware of an effort by Roberts et al. to 
update the 2015 North Atlantic right whale density models. As described 
in Roberts et al. (2017), the updates greatly expanded the dataset used 
to derive density outputs, especially within the planned survey area, 
as they incorporated a key dataset that was not included in the 2015 
model version: Aerial surveys conducted over multiple years by several 
organizations in the southeast United States. In addition, the AMAPPS 
survey data were incorporated into the revised models. By including 
these additional data sources, the number of right whale sightings used 
to inform the model within the planned survey area increased by 
approximately 2,500 sightings (approximately 40 sightings informing the 
2015 models versus approximately 2,560 sightings informing the updated 
2017 models). In addition, these models incorporated several 
improvements to minimize known biases and used an improved seasonal 
definition that more closely aligns with right whale biology. 
Importantly, the revised models showed a strong relationship between 
right whale abundance in the mid-Atlantic during the winter (December-
March) and distance to shore out to approximately 80 km (Roberts et 
al., 2017), which was previously estimated out to approximately 50 km 
(Roberts et al., 2015p). As described above, a 10 km buffer is provided 
to encompass the area within which sound exceeding 160 dB rms would 
reasonably be expected to occur. Mid-Atlantic SMAs for vessel speed 
limits are in effect from November 1 through April 30, while southeast 
SMAs are in effect from November 15 through April 15 (see 50 CFR 
224.105). Therefore, the area discussed here for spatial mitigation 
would be in effect from November 1 through April 30.
    While we acknowledge that some whales may be present at distances 
further offshore during the November through April restriction--though 
whales are not likely to occur in waters deeper than 1,500 m--and that 
there may be whales present during months outside the restriction 
(e.g., Davis et al., 2017; Krzystan et al., 2018), we have accounted 
for the best available information in reasonably limiting the potential 
for acoustic exposure of right whales to levels exceeding harassment 
thresholds. When coupled with the expanded shutdown provision described 
previously for right whales,

[[Page 63352]]

the prescribed mitigation may reasonably be expected to eliminate most 
potential for behavioral harassment of right whales.
    However, as discussed above, in lieu of this requirement, 
applicants may alternatively develop and submit a monitoring and 
mitigation plan for NMFS's approval that would be sufficient to achieve 
comparable protection for North Atlantic right whales. If approved, 
applicants would be required to maintain a minimum coastal standoff 
distance of 47 km from November through April while operating in 
adherence with the approved plan from 47 through 80 km offshore. (Note 
that the 80 km distance is assumed to represent to a reasonable extent 
right whale occurrence on the migratory pathway; therefore, under an 
approved plan the 10-km buffer would not be relevant.)
    DMAs are associated with a scheme established by the final rule for 
vessel speed limits (73 FR 60173; October 10, 2008; extended by 78 FR 
73726; December 9, 2013) to reduce the risk of ship strike for right 
whales. In association with those regulations, NMFS established a 
program whereby vessels are requested, but not required, to abide by 
speed restrictions or avoid locations when certain aggregations of 
right whales are detected outside SMAs. Generally, the DMA construct is 
intended to acknowledge that right whales can occur outside of areas 
where they predictably and consistently occur due to, e.g., varying 
oceanographic conditions that dictate prey concentrations. NMFS 
establishes DMAs by surveying right whale habitat and, when a specific 
aggregation is sighted, creating a temporary zone (i.e., DMA) around 
the aggregation. DMAs are in effect for 15 days when designated and 
automatically expire at the end of the period, but may be extended if 
whales are re-sighted in the same area.
    NMFS issues announcements of DMAs to mariners via its customary 
maritime communication media (e.g., NOAA Weather radio, websites, email 
and fax distribution lists) and any other available media outlets. 
Information on the possibility of establishment of such zones is 
provided to mariners through written media such as U.S. Coast Pilots 
and Notice to Mariners including, in particular, information on the 
media mariners should monitor for notification of the establishment of 
a DMA. Upon notice via the above media of DMA designation, survey 
operators must cease operation within 24 hours if within 10 km of the 
boundary of a designated DMA and may not conduct survey operations 
within 10 km of a designated DMA during the period in which the DMA is 
active. It is the responsibility of the survey operators to monitor 
appropriate media and to be aware of designated DMAs.
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    Other Species--Predicted acoustic exposures are moderate to high 
for certain potentially affected marine mammal species (see Table 6) 
and, regardless of the absolute numbers of predicted exposures, the 
scope of planned activities (i.e., survey activity throughout 
substantial portions of many species range and for substantial portions 
of the year) gives rise to concern regarding the impact on certain 
potentially affected stocks. Therefore, we take the necessary step of 
identifying additional spatiotemporal restrictions on survey effort, as 
described here (Figure 4 and Table 7). In response to public comment, 
where possible we conducted a quantitative assessment of take avoided 
(described previously in ``Estimated Take''). Our qualitative 
assessment leads us to believe that

[[Page 63354]]

implementation of these measures is expected to provide biologically 
meaningful benefit for the affected animals by restricting survey 
activity and the effects of the sound produced in areas of residency 
and/or preferred habitat that support higher densities for the stocks 
during substantial portions of the year.
    The restrictions described here are primarily targeted towards 
protection of sperm whales, beaked whales (i.e., Cuvier's beaked whale 
or Mesoplodon spp. but not the northern bottlenose whale; see 
``Description of Marine Mammals in the Area of the Specified 
Activity''), and pilot whales. For all three species or guilds, the 
amount of predicted exposures is moderate to high. The moderate to high 
amount of predicted exposures in conjunction with other contextual 
elements provides the impetus to develop appropriate restrictions. 
Beaked whales are considered to be a particularly acoustically 
sensitive species. The sperm whale is an endangered species, also 
considered to be acoustically sensitive and potentially subject to 
significant disturbance of important foraging behavior. Pilot whale 
populations in U.S. waters of the Atlantic are considered vulnerable 
due to high levels of mortality in commercial fisheries, and are 
therefore likely to be less resilient to other stressors, such as 
disturbance from the planned surveys.
    In some cases, we expect substantial subsidiary benefit for 
additional species that also find preferred habitat in the designated 
area of restriction. In particular, Area #4 (Figure 4), although 
delineated in order to specifically provide an area of anticipated 
benefit to beaked whales, sperm whales, and pilot whales, is expected 
to host a diverse cetacean fauna (e.g., McAlarney et al., 2015). Our 
analysis (described below) indicates that species most likely to derive 
subsidiary benefit from this time-area restriction include the 
bottlenose dolphin, Risso's dolphin, and common dolphin. For species 
with density predicted through stratified models, similar analysis is 
not possible and assumptions regarding potential benefit of time-area 
restrictions are based on known ecology of the species and sightings 
patterns and are less robust. Nevertheless, subsidiary benefit for 
Areas #1-3 (Figure 4) should be expected for species known to be 
present in these areas (e.g., assumed affinity for slope/abyss areas 
off Cape Hatteras): Kogia spp., pantropical spotted dolphin, Clymene 
dolphin, and rough-toothed dolphin.
    We described our rationale for and development of these time-area 
restrictions in detail in our Notice of Proposed IHAs; please see that 
document for more detail. Literature newly available since publication 
of the Notice of Proposed IHAs provides additional support for the 
importance of these areas. For example, McLellan et al. (2018), 
reporting the results of aerial surveys conducted from 2011-2015, 
provide additional confirmation that a portion of the region described 
below as Area #4 (``Hatteras and North'') hosts high densities of 
beaked whales, concluding that the area off Cape Hatteras at the 
convergence of the Labrador Current and Gulf Stream is a particularly 
important habitat for several species of beaked whales. Stanistreet et 
al. (2017) report the results of a multi-year (2011-2015) passive 
acoustic monitoring effort to assess year-round marine mammal 
occurrence along the continental slope, including four locations within 
the planned survey area (i.e., Norfolk Canyon, Cape Hatteras, Onslow 
Bay, and Jacksonville) and, in this paper, they further document the 
presence of beaked whales in Area #4. Stanistreet et al. (2018) report 
the results of this study for sperm whale occurrence at the same sites 
along the continental slope. These results showed that sperm whales 
were present frequently at the first three sites, with few detections 
at Jacksonville. The greatest monitoring effort was conducted at the 
Cape Hatteras site, where detections were made on 65 percent of 734 
recording days across all seasons. In addition to having the highest 
detection rate of sites within the specific geographic region (in 
conjunction with roughly double the amount of recording effort compared 
with the next highest site), Cape Hatteras exhibited the most distinct 
seasonal pattern of any recording site (Stanistreet et al., 2018). The 
authors reported consistently higher sperm whale occurrence at Cape 
Hatteras during the winter than any other season. On the basis of this 
new information, we shifted the timing of the seasonal restriction in 
Area #4 from July through September (as proposed) to January through 
March (i.e., ``winter''; Stanistreet et al., 2018). Our previously 
proposed timing of the seasonal restriction was based on barely 
discernable distribution shifts based on monthly model predictions 
(Roberts et al., 2016). However, the revised timing, as indicated by 
Stanistreet et al. (2018), is generally consistent with the seasonal 
shift in sperm whale concentrations previously described in the western 
North Atlantic (Perry et al., 1999, Waring et al., 2014).
    Please note that, following review of public comments, former Area 
#1 was eliminated from consideration (discussed in greater detail under 
``Comments and Responses''). Therefore, numbering of areas described 
here has shifted down by one as compared with the discussion presented 
in our Notice of Proposed IHAs, i.e., former Area #5 is now Area #4, 
etc. In order to consider potential restriction of survey effort in 
time and space, we considered the outputs of habitat-based predictive 
density models (Roberts et al., 2016) as well as available information 
concerning focused marine mammal studies within the survey areas, e.g., 
photo-identification, telemetry, acoustic monitoring. The latter 
information was used primarily to provide verification for some of the 
areas and times considered, and helps to confirm that areas of high 
predicted density are in fact preferred habitat for these species. We 
used the density model outputs by creating core abundance areas, i.e., 
an area that contains some percentage of predicted abundance for a 
given species or species group. We were not able to consider core 
abundance areas for species with stratified models showing uniform 
density; however, this information informs us as to whether those 
species may receive subsidiary benefit from a given time-area 
restriction.
    A core abundance area is the smallest area that represents a given 
percentage of abundance. As described in our Notice of Proposed IHAs, 
we created a range of core abundance areas for each species of interest 
and determined that in most cases the 25 percent core abundance area 
best balanced adequate protection for the target species with concerns 
regarding practicability for applicants. The larger the percentage of 
abundance captured, the larger the area. However, Area #4 was designed 
as a conglomerate by merging areas indicated to be important through 
the core abundance analysis and available scientific literature for 
beaked whales, pilot whales, and sperm whales. In particular, for sperm 
whales (which are predicted to be broadly distributed on the slope 
throughout the year), we included an area predicted to consistently 
host higher relative densities in all months (corresponding with the 
five percent core abundance threshold). We assessed different levels of 
core abundance in order to define a relatively restricted area of 
preferred habitat across all seasons. This area in the vicinity of the 
shelf break to the north of Cape Hatteras (which forms the

[[Page 63355]]

conglomerate Area #4), together with spatially separated canyon 
features contained within the 25 percent core abundance areas and 
previously identified as preferred habitat for beaked whales, form the 
basis for our time-area restriction for sperm whales. Core abundance 
maps are provided online at www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-atlantic.
    In summary, we require the following time-area restrictions:
     In order to protect coastal bottlenose dolphins, a 30-km 
coastal strip (20 km plus 10 km buffer) would be closed to use of the 
acoustic source year-round;
     In order to protect the North Atlantic right whale, a 90-
km coastal strip (80 km plus 10 km buffer) would be closed to use of 
the acoustic source from November through April (Figure 3) (or 
comparable protection would be provided through implementation of a 
NMFS-approved mitigation and monitoring plan at distances between 47-80 
km offshore). Dynamic management areas (buffered by 10 km) are also 
closed to use of the acoustic source when in effect;
    The 10-km buffer is built into the areas defined below and in Table 
7. Therefore, we do not separately mention the addition of the buffer.
     Deepwater canyon areas. Areas #1-3 (Figure 4) are defined 
in Table 7 and will be closed to use of the acoustic source year-round. 
Although they may be protective of additional species (e.g., Kogia 
spp.), Area #1 is expected to be particularly beneficial for beaked 
whales and Areas #2-3 are expected to be particularly beneficial for 
both beaked whales and sperm whales;
     Shelf break off Cape Hatteras and to the north (``Hatteras 
and North''), including slope waters around ``The Point.'' Area #4 is 
defined in Table 7 and will be closed to use of the acoustic source 
from January through March. Although this closure is expected to be 
beneficial for a diverse species assemblage, Area #4 is expected to be 
particularly beneficial for beaked whales, sperm whales, and pilot 
whales.

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[[Page 63357]]



   Table 7--Boundaries of Time-Area Restrictions Depicted in Figure 4
------------------------------------------------------------------------
            Area                    Latitude              Longitude
------------------------------------------------------------------------
1...........................  33[deg]31'16'' N      72[deg]52'07'' W
1...........................  33[deg]10'05'' N      72[deg]59'59'' W
1...........................  33[deg]11'23'' N      73[deg]19'36'' W
1...........................  33[deg]43'34'' N      73[deg]17'43'' W
1...........................  33[deg]59'43'' N      73[deg]10'16'' W
1...........................  34[deg]15'10'' N      72[deg]55'37'' W
1...........................  34[deg]14'02'' N      72[deg]36'00'' W
1...........................  34[deg]03'33'' N      72[deg]37'27'' W
1...........................  33[deg]53'00'' N      72[deg]44'31'' W
2...........................  34[deg]13'21'' N      74[deg]07'33'' W
2...........................  34[deg]00'07'' N      74[deg]26'41'' W
2...........................  34[deg]38'40'' N      75[deg]05'52'' W
2...........................  34[deg]53'24'' N      74[deg]51'11'' W
3...........................  36[deg]41'17'' N      71[deg]25'47'' W
3...........................  36[deg]43'20'' N      72[deg]13'25'' W
3...........................  36[deg]55'20'' N      72[deg]26'18'' W
3...........................  37[deg]52'21'' N      72[deg]22'31'' W
3...........................  37[deg]43'54'' N      72[deg]00'40'' W
3...........................  37[deg]09'52'' N      72[deg]04'31'' W
3...........................  36[deg]52'01'' N      71[deg]24'31'' W
4...........................  37[deg]08'30'' N      74[deg]01'42'' W
4...........................  36[deg]15'12'' N      73[deg]48'37'' W
4...........................  35[deg]53'14'' N      73[deg]49'02'' W
4...........................  34[deg]23'07'' N      75[deg]21'33'' W
4...........................  33[deg]47'37'' N      75[deg]27'25'' W
4...........................  33[deg]48'31'' N      75[deg]52'58'' W
4...........................  34[deg]23'57'' N      75[deg]52'50'' W
4...........................  35[deg]22'29'' N      74[deg]51'50'' W
4...........................  36[deg]32'31'' N      74[deg]49'31'' W
4...........................  37[deg]05'39'' N      74[deg]45'37'' W
4...........................  37[deg]27'53'' N      74[deg]32'40'' W
4...........................  38[deg]23'15'' N      73[deg]45'06'' W
4...........................  38[deg]11'17'' N      73[deg]06'36'' W
------------------------------------------------------------------------

Vessel Strike Avoidance

    These measures apply to all vessels associated with the planned 
survey activity (e.g., source vessels, chase vessels, supply vessels); 
however, we note that these requirements do not apply in any case where 
compliance would create an imminent and serious threat to a person or 
vessel or to the extent that a vessel is restricted in its ability to 
maneuver and, because of the restriction, cannot comply. These measures 
include the following:
    1. Vessel operators and crews must maintain a vigilant watch for 
all marine mammals and slow down, stop their vessel, or alter course, 
as appropriate and regardless of vessel size, to avoid striking any 
marine mammal. A single marine mammal at the surface may indicate the 
presence of submerged animals in the vicinity of the vessel; therefore, 
precautionary measures should be exercised when an animal is observed. 
A visual observer aboard the vessel must monitor a vessel strike 
avoidance zone around the vessel (specific distances detailed below), 
to ensure the potential for strike is minimized. Visual observers 
monitoring the vessel strike avoidance zone can be either third-party 
observers or crew members, but crew members responsible for these 
duties must be provided sufficient training to distinguish marine 
mammals from other phenomena and broadly to identify a marine mammal to 
broad taxonomic group (i.e., as a right whale, other whale, or other 
marine mammal). In this context, ``other whales'' includes sperm whales 
and all baleen whales other than right whales;
    2. All vessels, regardless of size, must observe the 10 kn speed 
restriction in specific areas designated for the protection of North 
Atlantic right whales: Any DMAs when in effect, the Mid-Atlantic SMAs 
(from November 1 through April 30), and critical habitat and the 
Southeast SMA (from November 15 through April 15). See 
www.fisheries.noaa.gov/national/endangered-species-conservation/reducing-ship-strikes-north-atlantic-right-whales for more information 
on these areas;
    3. Vessel speeds must also be reduced to 10 kn or less when mother/
calf pairs, pods, or large assemblages of any marine mammal are 
observed near a vessel;
    4. All vessels must maintain a minimum separation distance of 500 m 
from right whales. If a whale is observed but cannot be confirmed as a 
species other than a right whale, the vessel operator must assume that 
it is a right whale and take appropriate action;
    5. All vessels must maintain a minimum separation distance of 100 m 
from sperm whales and all other baleen whales;
    6. All vessels must attempt to maintain a minimum separation 
distance of 50 m from all other marine mammals, with an exception made 
for those animals that approach the vessel; and
    7. When marine mammals are sighted while a vessel is underway, the 
vessel should take action as necessary to avoid violating the relevant 
separation distance (e.g., attempt to remain parallel to the animal's 
course, avoid excessive speed or abrupt changes in direction until the 
animal has left the area). If marine mammals are sighted within the 
relevant separation distance, the vessel should reduce speed and shift 
the engine to neutral, not engaging the engines until animals are clear 
of the area. This recommendation does not apply to any vessel towing 
gear.

General Measures

    All vessels associated with survey activity (e.g., source vessels, 
chase vessels, supply vessels) must have a functioning Automatic 
Identification System (AIS) onboard and operating at all times, 
regardless of whether AIS would otherwise be required. Vessel names and 
call signs must be provided to NMFS, and applicants must notify NMFS 
when survey vessels are operating.
    We have carefully evaluated the suite of mitigation measures 
described here and considered a range of other measures in the context 
of ensuring that we prescribe the means of effecting the least 
practicable adverse impact on the affected marine mammal species and 
stocks and their habitat. Based on our evaluation of these measures, we 
have determined that the required mitigation measures provide the means 
of effecting the least practicable adverse impact on marine mammal 
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 the authorized taking. NMFS's MMPA 
implementing regulations further describe the information that an 
applicant should provide when requesting an authorization (50 CFR 
216.104(a)(13)), including the means of accomplishing the necessary 
monitoring and reporting that will result in increased knowledge of the 
species and the level of taking or impacts on populations of marine 
mammals. Effective reporting is critical both to compliance as well as 
ensuring that the most value is obtained from the required monitoring.
    Monitoring and reporting requirements prescribed by NMFS should 
contribute to improved understanding of one or more of the following:
     Occurrence of marine mammal species in action area (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

[[Page 63358]]

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 important physical components of marine 
mammal habitat); and
     Mitigation and monitoring effectiveness.

Changes From the Notice of Proposed IHAs

    Here we summarize substantive changes to monitoring and reporting 
requirements from our Notice of Proposed IHAs. All changes were made on 
the basis of review of public comments received and/or review of new 
information.
     As described in our Notice of Proposed IHAs, we 
preliminarily reached small numbers findings for some species on the 
basis of the proposed limitation of authorized take to approximately 
one-third of the abundance estimate deemed at the time to be most 
appropriate. In order to ensure that IHA-holders would not exceed this 
cap without limiting the planned survey activity, we proposed to 
require interim reporting in which IHA-holders would report all 
observations of marine mammals as well as corrected numbers of marine 
mammals ``taken.'' We received information from several commenters--
including several of the applicants--strongly indicating that such a de 
facto limitation, coupled with a novel reporting requirement, was 
impracticable. In summary, commenters noted that such surveys are 
multi-million dollar endeavors and stated that the surveys would simply 
not be conducted rather than commit such costs to the survey in the 
face of significant uncertainty as to whether the survey might be 
suddenly shut down as a result of reaching a pre-determined cap on the 
basis of novel modeling of ``corrected'' takes. We also received many 
comments indicating that our small numbers analyses were flawed and, as 
described in detail later in this notice (see ``Small Numbers 
Analyses'') we reconsidered the available information and re-evaluated 
our analyses in response to these comments. As a result of our revised 
small numbers analyses, such a cap coupled with reporting scheme is not 
necessary. Further, we agree with commenters that the proposal 
presented significant practicability concerns. Therefore, the proposed 
``interim'' reporting requirement is eliminated.
     Separately, while we recognize the importance of producing 
the most accurate estimates of actual take possible, we agree that the 
proposed approach to correcting observations to produce estimates of 
actual takes was (1) not the best available approach; (2) is novel in 
that it has not been previously required of applicants conducting 
similar activities; and (3) may not be appropriate for application to 
observations conducted from working source vessels. We have adopted a 
different approach to performing these ``corrections,'' as recommended 
through comment from the Marine Mammal Commission, but in this case we 
will perform these corrections upon submission of reports from IHA-
holders and evaluate the appropriateness of this approach and the 
validity of the results prior to requiring it for future IHAs.
     As a result of concerns expressed through public comment, 
we have revised requirements relating to reporting of injured or dead 
marine mammals and have added newly crafted requirements relating to 
actions that should be taken in response to stranding events in certain 
circumstances.
    Monitoring requirements are the same for all applicants, and a 
single discussion is provided here.

PSO Eligibility and Qualifications

    All PSO resumes must be submitted to NMFS and PSOs must be approved 
by NMFS after a review of their qualifications. These qualifications 
include whether the individual has successfully completed the necessary 
training (see ``Training,'' below) and, if relevant, whether the 
individual has the requisite experience (and is in good standing). PSOs 
should provide a current resume and information related to PSO 
training; submitted resumes should not include superfluous information. 
Information related to PSO training should include (1) a course 
information packet that includes the name and qualifications (e.g., 
experience, training, or education) of the instructor(s), the course 
outline or syllabus, and course reference material; and (2) a document 
stating the PSO's successful completion of the course. PSOs must be 
trained biologists, with the following minimum qualifications:
     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;
     Experience and ability to conduct field observations and 
collect data according to assigned protocols (may include academic 
experience) and experience with data entry on computers;
     Visual acuity in both eyes (correction is permissible) 
sufficient for discernment of moving targets at the water's surface 
with ability to estimate target size and distance; use of binoculars 
may be necessary to correctly identify the target (required for visual 
PSOs only);
     Experience or training in the field identification of 
marine mammals, including the identification of behaviors (required for 
visual PSOs only);
     Sufficient training, orientation, or experience with the 
survey operation to ensure personal safety during observations;
     Writing skills sufficient to prepare a report of 
observations (e.g., description, summary, interpretation, analysis) 
including but not limited to the number and species of marine mammals 
observed; marine mammal behavior; and descriptions of activity 
conducted and implementation of mitigation;
     Ability to communicate orally, by radio or in person, with 
survey personnel to provide real-time information on marine mammals 
detected in the area as necessary; and
     Successful completion of relevant training (described 
below), including completion of all required coursework and passing (80 
percent or greater) a written and/or oral examination developed for the 
training program.
    The educational requirements may be waived if the PSO has acquired 
the relevant skills through alternate experience. Requests for such a 
waiver must include written justification, and prospective PSOs granted 
waivers must satisfy training requirements described below. Alternate 
experience that may be considered includes, but is not limited to, the 
following:
     Secondary education and/or experience comparable to PSO 
duties;
     Previous work experience conducting academic, commercial, 
or government-sponsored marine mammal surveys; and
     Previous work experience as a PSO; the PSO should 
demonstrate good standing and consistently good performance of PSO 
duties.
    Training--NMFS does not currently approve specific training 
programs; however, acceptable training may include training previously 
approved by BSEE, or training that adheres generally to the 
recommendations provided by ``National Standards for a Protected 
Species Observer and Data Management

[[Page 63359]]

Program: A Model Using Geological and Geophysical Surveys'' (Baker et 
al., 2013). Those recommendations include the following topics for 
training programs:
     Life at sea, duties, and authorities;
     Ethics, conflicts of interest, standards of conduct, and 
data confidentiality;
     Offshore survival and safety training;
     Overview of oil and gas activities (including geophysical 
data acquisition operations, theory, and principles) and types of 
relevant sound source technology and equipment;
     Overview of the MMPA and ESA as they relate to protection 
of marine mammals;
     Mitigation, monitoring, and reporting requirements as they 
pertain to geophysical surveys;
     Marine mammal identification, biology and behavior;
     Background on underwater sound;
     Visual surveying protocols, distance calculations and 
determination, cues, and search methods for locating and tracking 
different marine mammal species (visual PSOs only);
     Optimized deployment and configuration of PAM equipment to 
ensure effective detections of cetaceans for mitigation purposes (PAM 
operators only);
     Detection and identification of vocalizing species or 
cetacean groups (PAM operators only);
     Measuring distance and bearing of vocalizing cetaceans 
while accounting for vessel movement (PAM operators only);
     Data recording and protocols, including standard forms and 
reports, determining range, distance, direction, and bearing of marine 
mammals and vessels; recording GPS location coordinates, weather 
conditions, Beaufort wind force and sea state, etc.;
     Proficiency with relevant software tools;
     Field communication/support with appropriate personnel, 
and using communication devices (e.g., two-way radios, satellite 
phones, internet, email, facsimile);
     Reporting of violations, noncompliance, and coercion; and
     Conflict resolution.
    PAM operators should regularly refresh their detection skills 
through practice with simulation-modeling software, and should keep up 
to date with training on the latest software/hardware advances.

Visual Monitoring

    The lead PSO is responsible for establishing and maintaining clear 
lines of communication with vessel crew. The vessel operator shall work 
with the lead PSO to accomplish this and shall ensure any necessary 
briefings are provided for vessel crew to understand mitigation 
requirements and protocols. While on duty, PSOs will continually scan 
the water surface in all directions around the acoustic source and 
vessel for presence of marine mammals, using a combination of the naked 
eye and high-quality binoculars, from optimum vantage points for 
unimpaired visual observations with minimum distractions. PSOs will 
collect observational data for all marine mammals observed, regardless 
of distance from the vessel, including species, group size, presence of 
calves, distance from vessel and direction of travel, and any observed 
behavior (including an assessment of behavioral responses to survey 
activity). Upon observation of marine mammal(s), a PSO will record the 
observation and monitor the animal's position (including latitude/
longitude of the vessel and relative bearing and estimated distance to 
the animal) until the animal dives or moves out of visual range of the 
observer, and a PSO will continue to observe the area to watch for the 
animal to resurface or for additional animals that may surface in the 
area. PSOs will also record environmental conditions at the beginning 
and end of the observation period and at the time of any observations, 
as well as whenever conditions change significantly in the judgment of 
the PSO on duty.
    The vessel operator must provide bigeye binoculars (e.g., 25 x 150; 
2.7 view angle; individual ocular focus; height control) of appropriate 
quality (e.g., Fujinon or equivalent) solely for PSO use. These should 
be pedestal-mounted on the deck at the most appropriate vantage point 
that provides for optimal sea surface observation, PSO safety, and safe 
operation of the vessel. The operator must also provide a night-vision 
device suited for the marine environment for use during nighttime ramp-
up pre-clearance, at the discretion of the PSOs. NVDs may include night 
vision binoculars or monocular or forward-looking infrared device 
(e.g., Exelis PVS-7 night vision goggles; Night Optics D-300 night 
vision monocular; FLIR M324XP thermal imaging camera or equivalents). 
At minimum, the device should feature automatic brightness and gain 
control, bright light protection, infrared illumination, and optics 
suited for low-light situations. Other required equipment, which should 
be made available to PSOs by the third-party observer provider, 
includes reticle binoculars (e.g., 7 x 50) of appropriate quality 
(e.g., Fujinon or equivalent), GPS, digital single-lens reflex camera 
of appropriate quality (e.g., Canon or equivalent), compass, and any 
other tools necessary to adequately perform the tasks described above, 
including accurate determination of distance and bearing to observed 
marine mammals.
    Individuals implementing the monitoring protocol will assess its 
effectiveness using an adaptive approach. Monitoring biologists will 
use their best professional judgment throughout implementation and seek 
improvements to these methods when deemed appropriate. Specifically, 
implementation of shutdown requirements will be made on the basis of 
the PSO's best professional judgment. While PSOs should not insert 
undue ``precaution'' into decision-making, it is expected that PSOs may 
call for mitigation action on the basis of reasonable certainty 
regarding the need for such action, as informed by professional 
judgment. Any modifications to protocol will be coordinated between 
NMFS and the applicant.

Acoustic Monitoring

    Monitoring of a towed PAM system is required at all times, from 30 
minutes prior to ramp-up and throughout all use of the acoustic source. 
Towed PAM systems generally consist of hardware (e.g., hydrophone 
array, cables) and software (e.g., data processing and monitoring 
system). Some type of automated detection software must be used; while 
not required, we recommend use of industry standard software (e.g., 
PAMguard, which is open source). Hydrophone signals are processed for 
output to the PAM operator with software designed to detect marine 
mammal vocalizations. Current PAM technology has some limitations 
(e.g., limited directional capabilities and detection range, masking of 
signals due to noise from the vessel, source, and/or flow, 
localization) and there are no formal guidelines currently in place 
regarding specifications for hardware, software, or operator training 
requirements.
    Our requirement to use PAM refers to the use of calibrated 
hydrophone arrays with full system redundancy to detect, identify, and 
estimate distance and bearing to vocalizing cetaceans, to the extent 
possible. With regard to calibration, the PAM system should have at 
least one calibrated hydrophone, sufficient for determining whether 
background noise levels on the towed PAM system are sufficiently low to 
meet performance expectations. Additionally,

[[Page 63360]]

if multiple hydrophone types occur in a system (i.e., monitor different 
bandwidths), then one hydrophone from each such type should be 
calibrated, and whenever sets of hydrophones (of the same type) are 
sufficiently spatially separated such that they would be expected to 
experience ambient noise environments that differ by 6 dB or more 
across any integrated species cluster bandwidth, then at least one 
hydrophone from each set should be calibrated. The arrays should 
incorporate appropriate hydrophone elements (1 Hz to 180 kHz range) and 
sound data acquisition card technology for sampling relevant 
frequencies (i.e., to 360 kHz). This hardware should be coupled with 
appropriate software to aid monitoring and listening by a PAM operator 
skilled in bioacoustics analysis and computer system specifications 
capable of running appropriate software.
    Applicant-specific PAM plans were made available for review either 
in individual applications or as separate documents online at: 
www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-atlantic. As recommended by 
Thode et al. (2017), PAM plans should, at minimum, adequately address 
and describe (1) the hardware and software planned for use, including a 
hardware performance diagram demonstrating that the sensitivity and 
dynamic range of the hardware is appropriate for the operation; (2) 
deployment methodology, including target depth/tow distance; (3) 
definitions of expected operational conditions, used to summarize 
background noise statistics; (4) proposed detection-classification-
localization methodology, including anticipated species clusters (using 
a cluster definition table), target minimum detection range for each 
cluster, and the proposed localization method for each cluster; (5) 
operation plans, including the background noise sampling schedule; (6) 
array design considerations for noise abatement; and (7) cluster-
specific details regarding which real-time displays and automated 
detectors the operator would monitor.
    In coordination with vessel crew, the lead PAM operator will be 
responsible for deployment, retrieval, and testing and optimization of 
the hydrophone array. While on duty, the PAM operator must diligently 
listen to received signals and/or monitoring display screens in order 
to detect vocalizing cetaceans, except as required to attend to PAM 
equipment. The PAM operator must use appropriate sample analysis and 
filtering techniques and, as described below, must report all cetacean 
detections. While not required prior to development of formal standards 
for PAM use, we recommend that vessel self-noise assessments are 
undertaken during mobilization in order to optimize PAM array 
configuration according to the specific noise characteristics of the 
vessel and equipment involved, and to refine expectations for distance/
bearing estimations for cetacean species during the survey. Copies of 
any vessel self-noise assessment reports must be included with the 
summary trip report.

Data Collection

    PSOs must use standardized data forms, whether hard copy or 
electronic. PSOs will record detailed information about any 
implementation of mitigation requirements, including the distance of 
animals to the acoustic source and description of specific actions that 
ensued, the behavior of the animal(s), any observed changes in behavior 
before and after implementation of mitigation, and if shutdown was 
implemented, the length of time before any subsequent ramp-up of the 
acoustic source to resume survey. If required mitigation was not 
implemented, PSOs should submit a description of the circumstances. We 
require that, at a minimum, the following information be reported:
     Vessel names (source vessel and other vessels associated 
with survey) and call signs;
     PSO names and affiliations;
     Dates of departures and returns to port with port name;
     Dates and times (Greenwich Mean Time) of survey effort and 
times corresponding with PSO effort;
     Vessel location (latitude/longitude) when survey effort 
begins and ends; vessel location at beginning and end of visual PSO 
duty shifts;
     Vessel heading and speed at beginning and end of visual 
PSO duty shifts and upon any line change;
     Environmental conditions while on visual survey (at 
beginning and end of PSO shift and whenever conditions change 
significantly), including wind speed and direction, Beaufort sea state, 
Beaufort wind force, swell height, weather conditions, cloud cover, sun 
glare, and overall visibility to the horizon;
     Factors that may be contributing to impaired observations 
during each PSO shift change or as needed as environmental conditions 
change (e.g., vessel traffic, equipment malfunctions);
     Survey activity information, such as acoustic source power 
output while in operation, number and volume of airguns operating in 
the array, tow depth of the array, and any other notes of significance 
(i.e., pre-ramp-up survey, ramp-up, shutdown, testing, shooting, ramp-
up completion, end of operations, streamers, etc.);
     If a marine mammal is sighted, the following information 
should be recorded:
    [cir] Watch status (sighting made by PSO on/off effort, 
opportunistic, crew, alternate vessel/platform);
    [cir] PSO who sighted the animal;
    [cir] Time of sighting;
    [cir] Vessel location at time of sighting;
    [cir] Water depth;
    [cir] Direction of vessel's travel (compass direction);
    [cir] Direction of animal's travel relative to the vessel;
    [cir] Pace of the animal;
    [cir] Estimated distance to the animal and its heading relative to 
vessel at initial sighting;
    [cir] Identification of the animal (e.g., genus/species, lowest 
possible taxonomic level, or unidentified); also note the composition 
of the group if there is a mix of species;
    [cir] Estimated number of animals (high/low/best);
    [cir] Estimated number of animals by cohort (adults, yearlings, 
juveniles, calves, group composition, etc.);
    [cir] Description (as many distinguishing features as possible of 
each individual seen, including length, shape, color, pattern, scars or 
markings, shape and size of dorsal fin, shape of head, and blow 
characteristics);
    [cir] Detailed behavior observations (e.g., number of blows, number 
of surfaces, breaching, spyhopping, diving, feeding, traveling; as 
explicit and detailed as possible; note any observed changes in 
behavior);
    [cir] Animal's closest point of approach (CPA) and/or closest 
distance from the acoustic source;
    [cir] Platform activity at time of sighting (e.g., deploying, 
recovering, testing, shooting, data acquisition, other); and
    [cir] Description of any actions implemented in response to the 
sighting (e.g., delays, shutdown, ramp-up, speed or course alteration, 
etc.); time and location of the action should also be recorded;
     If a marine mammal is detected while using the PAM system, 
the following information should be recorded:
    [cir] An acoustic encounter identification number, and whether the 
detection was linked with a visual sighting;
    [cir] Time when first and last heard;
    [cir] Types and nature of sounds heard (e.g., clicks, whistles, 
creaks, burst pulses, continuous, sporadic, strength of signal, etc.); 
and

[[Page 63361]]

    [cir] Any additional information recorded such as water depth of 
the hydrophone array, bearing of the animal to the vessel (if 
determinable), species or taxonomic group (if determinable), 
spectrogram screenshot, and any other notable information.

Reporting

    Applicants must submit a draft comprehensive report to NMFS within 
90 days of the completion of survey effort or expiration of the IHA 
(whichever comes first), and must include all information described 
above under ``Data Collection.'' If a subsequent IHA request is 
planned, a report must be submitted a minimum of 75 days prior to the 
requested date of issuance for the subsequent IHA. The report must 
describe the operations conducted and sightings of marine mammals near 
the operations; provide full documentation of methods, results, and 
interpretation pertaining to all monitoring; summarize the dates and 
locations of survey operations, and all marine mammal sightings (dates, 
times, locations, activities, associated survey activities); and 
provide information regarding locations where the acoustic source was 
used. The IHA-holder shall provide geo-referenced time-stamped vessel 
tracklines for all time periods in which airguns (full array or single) 
were operating. Tracklines should include points recording any change 
in airgun status (e.g., when the airguns began operating, when they 
were turned off). GIS files shall be provided in ESRI shapefile format 
and include the UTC date and time, latitude in decimal degrees, and 
longitude in decimal degrees. All coordinates should be referenced to 
the WGS84 geographic coordinate system. In addition to the report, all 
raw observational data shall be made available to NMFS. This report 
must also include a validation document concerning the use of PAM, 
which should include necessary noise validation diagrams and 
demonstrate whether background noise levels on the PAM deployment 
limited achievement of the planned detection goals. The draft report 
must be accompanied by a certification from the lead PSO as to the 
accuracy of the report. A final report must be submitted within 30 days 
following resolution of any NMFS comments on the draft report.
    In association with the final comprehensive reports, NMFS will 
calculate and make available estimates of the number of takes based on 
the observations and in consideration of the detectability of the 
marine mammal species observed (as described below). PSO effort, survey 
details, and sightings data should be recorded continuously during 
surveys and reports prepared each day during which survey effort is 
conducted. As described below, NMFS will use these observational data 
to calculate corrected numbers of marine mammals taken.
    There are multiple reasons why marine mammals may be present and 
yet be undetected by observers. Animals are missed because they are 
underwater (availability bias) or because they are available to be 
seen, but are missed by observers (perception and detection biases) 
(e.g., Marsh and Sinclair, 1989). Negative bias on perception or 
detection of an available animal may result from environmental 
conditions, limitations inherent to the observation platform, or 
observer ability. In this case, we do not have prior knowledge of any 
potential negative bias on detection probability due to observation 
platform or observer ability. Therefore, observational data corrections 
must be made with respect to assumed species-specific detection 
probability as evaluated through consideration of environmental factors 
(e.g., f(0)). In order to make these corrections, we plan to use a 
method recommended by the Marine Mammal Commission (MMC) for estimating 
the number of cetaceans in the vicinity of the surveys based on the 
number of groups detected. This method is described in full in the 
MMC's comment letter for these actions, which is available online at: 
www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-atlantic.

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).

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:
     If at any time, the marine mammals 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

[[Page 63362]]

shutdown around the animals' location 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.
    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.

Negligible Impact Analyses and Determinations

    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 a negligible impact determination. In 
addition to considering estimates of the number of marine mammals that 
might be ``taken'' by mortality, serious injury, and Level A or Level B 
harassment, we consider other factors, such as the type of take, the 
likely nature of any behavioral responses (e.g., intensity, duration), 
the context of any such responses (e.g., critical reproductive time or 
location, migration), as well as effects on habitat, and the likely 
effectiveness of mitigation. We also assess the number, intensity, and 
context of estimated takes by evaluating this information relative to 
population status. Consistent with the 1989 preamble for NMFS's 
implementing regulations (54 FR 40338; September 29, 1989), the impacts 
from other past and ongoing anthropogenic activities are incorporated 
into these analyses 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).
    We first provide a generic description of our approach to the 
negligible impact analyses for these actions, which incorporates 
elements of the assessment methodology described by Wood et al. (2012), 
before providing applicant-specific analysis. For each potential 
activity-related stressor, we consider the potential effects to marine 
mammals and the likely significance of those effects to the species or 
stock as a whole. Potential risk due to vessel collision and related 
mitigation measures as well as potential risk due to entanglement and 
contaminant spills were addressed under ``Mitigation'' and in the 
``Potential Effects of the Specified Activity on Marine Mammals'' 
section of our Notice of Proposed IHAs and are not discussed further, 
as there are minimal risks expected from these potential stressors.
    Our analyses incorporate a simple matrix assessment approach to 
generate relative impact ratings that couple potential magnitude of 
effect on a stock and likely consequences of those effects for 
individuals, given biologically relevant information (e.g., 
compensatory ability). These impact ratings are then combined with 
consideration of contextual information, such as the status of the 
stock or species, in conjunction with our required mitigation strategy, 
to ultimately inform our negligible impact determinations. Figure 5 
provides an overview of this framework. Elements of this approach are 
subjective and relative within the context of these particular actions 
and, overall, these analyses necessarily require the application of 
professional judgment. As shown in Figure 5, it is important to be 
clear that the ``impact rating'' does not equate to the ultimate 
assessment of impact to the species or stock, i.e., the negligible 
impact determination. The ``impact rating'' is considered in 
conjunction with relevant contextual factors to inform the overall 
assessment of impact to the species or stock.

Changes From the Notice of Proposed IHAs

    Following review of public comments, we largely retain the 
negligible impact analysis framework and specific analyses described in 
our Notice of Proposed IHAs. However, we have made several adjustments 
on the basis of our review.
     As a result of our revised take estimates (``Estimated 
Take'') and reconsideration of available information (``Description of 
Marine Mammals in the Area of the Specified Activities'' and ``Small 
Numbers Analyses''), the amount of take has changed for some species 
for some applicants. In some cases, this leads to a change in overall 
magnitude rating.

[[Page 63363]]

[GRAPHIC] [TIFF OMITTED] TN07DE18.008

     We agree with commenters who pointed out that a de minimis 
magnitude rating should not render consequences for individuals 
irrelevant to the impact rating. Rather, the assessed level of 
consequences pairs with the magnitude rating to produce the overall 
impact rating. In our preliminary negligible impact analyses, for 
example, mysticete whales with a de minimis amount of take were 
assigned an overall de minimis impact rating, as consequences were 
considered not applicable in cases where a de minimis magnitude rating 
was assigned. However, the assessed level of potential consequences for 
individual mysticetes of ``medium''--which is related to inherent 
vulnerabilities of the taxon, and is therefore not dependent on the 
specific magnitude rating--would still exist, regardless of the amount 
of take/magnitude rating. Therefore, under our revised approach, a 
mysticete whale with a de minimis magnitude rating is now assigned a 
low impact rating.
    In order to reflect the change described in the preceding 
paragraph, we have adjusted the impact rating scheme (Table 9). Whereas 
before a de minimis magnitude rating previously resulted in a de 
minimis impact rating regardless of assessed potential consequences to 
individuals, a de minimis magnitude rating now leads to a de minimis 
impact rating only if the assessed consequences are low; the de minimis 
impact rating with medium assessed potential consequences for 
individuals would lead to an impact rating of low.

Impact Rating

    Magnitude--We consider magnitude of effect as a semi-quantitative 
evaluation of measurable factors presented as relative ratings that 
address the spatiotemporal extent of expected effects to a species or 
stock and their habitat. Magnitude ratings are developed as a 
combination of measurable factors: The amount of take, the spatial 
extent of the effects in the context of the species range, and the 
duration of effects.
Amount of Take
    We consider authorized take by Level B harassment of less than five 
percent of the most appropriate population abundance to be de minimis, 
while authorized Level B harassment taking between 5-15 percent is low. 
A moderate amount of authorized taking by Level B harassment would be 
from 15-25 percent, and high above 25 percent.
    Although we do not define quantitative metrics relating to amount 
of potential take by Level A harassment, for all applicant companies 
the expected potential for Level A harassment and, therefore, the 
authorized taking, is very low (Table 6). For these specified 
activities, as described in detail in ``Estimated Take,'' the best 
available science indicates that there is no reasonable potential for 
Level A harassment of mid-frequency cetaceans, while there is only 
limited potential for Level A harassment of low-frequency cetaceans 
when considering that Level A harassment is dependent on accumulation 
of energy from a mobile acoustic source. Similarly, estimated takes by 
Level A harassment are very low for all high-frequency cetacean 
species.
    Overall, while these limited incidents of Level A harassment would 
result in

[[Page 63364]]

permanent hearing loss, the effects of such hearing loss are expected 
to be minor for several reasons. First, the acoustic thresholds used in 
our exposure analysis represent thresholds for the onset of PTS (i.e., 
the minimum sound levels at which minor PTS could occur; NMFS, 2018), 
not thresholds for moderate or severe PTS. In order to determine the 
likelihood of moderate or severe PTS, one needs to consider the actual 
level of exposure (for high-frequency cetaceans) or, for low-frequency 
cetaceans, the duration of exposure at the PTS onset threshold 
distances from the airgun arrays or closer. High-frequency cetaceans 
that may be present (i.e., harbor porpoise and Kogia spp.) are known to 
be behaviorally sensitive to acoustic disturbance and are unlikely to 
approach source vessels at distances that might lead to more severe 
PTS. Similarly, mysticete whales are known to display avoidance 
behaviors in the vicinity of airgun surveys (e.g., Ellison et al., 
2016) and, when considered in conjunction with the estimated distances 
to the thresholds for the onset of PTS (Table 5), it is likely that 
such PTS exposure would be brief and at or near PTS onset levels. For 
example, a recent study analyzing 16 years of PSO data consisting of 
marine mammal observations during seismic surveys in waters off the 
United Kingdom found that the median closest approach by fin whales 
during active airgun use was 1,225 m (Stone et al., 2017), a distance 
well beyond the PTS onset threshold distances estimated for these 
specific airgun arrays. The degree of PTS would be further minimized 
through use of the ramp-up procedure, which will alert animals to the 
source prior to its achieving full power, and through shutdown 
requirements, which will not necessarily prevent exposure but are 
expected to reduce the intensity and duration of exposure. Available 
data suggest that such PTS would primarily occur at frequencies where 
the majority of the energy from airgun sounds occurs (below 500 Hz). 
For high-frequency cetaceans, any PTS would therefore occur at 
frequencies well outside their estimated range of maximum sensitivity. 
For low-frequency cetaceans, these frequencies overlap with the 
frequencies used for communication and so may interfere somewhat with 
their ability to communicate, though still below the estimated range of 
maximum sensitivity for these species. The expected mild PTS would not 
likely meaningfully impact the affected high-frequency cetaceans, and 
may have minor effects on the ability of affected low-frequency 
cetaceans to hear conspecific calls and/or other environmental cues. 
For all applicants, the expected effects of Level A harassment on all 
stocks to which such take may occur is appropriately considered de 
minimis.
Spatial Extent
    Spatial extent relates to overlap of the expected range of the 
affected stock with the expected footprint of the stressor. While we do 
not define quantitative metrics relative to assessment of spatial 
extent, a relatively low impact is defined here as a localized effect 
on the stock's range, a relatively moderate impact is defined as a 
regional-scale effect (meaning that the overlap between stressor and 
range was partial), and a relatively high impact is one in which the 
degree of overlap between stressor and range is near total. For a 
mobile activity occurring over a relatively large, regional-scale area, 
this categorization is made largely on the basis of the stock range in 
relation to the action area. For example, the harbor porpoise is 
expected to occur almost entirely outside of the planned survey areas 
(Hayes et al., 2017; Roberts et al., 2016) and therefore despite the 
large extent of planned survey activity, the spatial extent of 
potential stressor effect would be low. A medium degree of effect would 
be expected for a species such as the Risso's dolphin, which has a 
distribution in shelf and slope waters along the majority of the U.S. 
Atlantic coast, and which also would be expected to have greater 
abundance in mid-Atlantic waters north of the survey areas in the 
summer (Hayes et al., 2018a; Roberts et al., 2016). This means that the 
extent of potential stressor for this species would at all times be 
expected to have some overlap with a portion of the stock, while some 
portion (increasing in summer and fall months) would at all times be 
outside the stressor footprint. A higher degree of impact with regard 
to spatial extent would be expected for a species such as the Clymene 
dolphin, which is expected to have a generally more southerly 
distribution (Waring et al., 2014; Roberts et al., 2016) and thus more 
nearly complete overlap with the expected stressor footprint in the 
specific geographic region.
    In Tables 10-14 below, spatial extent is presented as a range for 
certain species with known migratory patterns. We expect spatial extent 
(overlap of stock range with planned survey area) to be low for right 
whales from May through October but moderate from November through 
April, due to right whale movements into southeastern shelf waters in 
the winter for calving. The overlap is considered moderate during 
winter because not all right whales make this winter migration, and 
those that do are largely found in shallow waters where little survey 
effort is planned (and when/where we prescribe a spatial restriction 
that would largely preclude any potential overlap between right whales 
and effects of the survey activities). Spatial extent for humpback 
whales is expected to be low for most of the year, but likely moderate 
during winter, while spatial extent for minke whales is likely low in 
summer, moderate in spring and fall, and high in winter. While we 
consider spatial extent to be low year-round for fin whales, their 
range overlap with the planned survey area does vary across the seasons 
and is closer to moderate in winter and spring. We expect spatial 
extent for common dolphins to be lower in fall but generally moderate. 
Similarly, we expect spatial extent for Risso's dolphins to be lower in 
summer but generally moderate. Although survey plans differ across 
applicants, all cover large spatial scales that extend throughout much 
of the specific geographic region, and we do not expect meaningful 
differences across surveys with regard to spatial extent.
Temporal Extent
    The temporal aspect of the stressor is measured through 
consideration of duration and frequency. Duration describes how long 
the effects of the stressor last. Temporal frequency may range from 
continuous to isolated (may occur one or two times), or may be 
intermittent. We consider a temporary effect lasting up to one month 
(prior to the animal or habitat reverting to a ``normal'' condition) to 
be short-term, whereas long[hyphen]term effects are more permanent, 
lasting beyond one season (with animals or habitat potentially 
reverting to a ``normal'' condition). Moderate[hyphen]term is defined 
as between 1-3 months. These metrics and their potential combinations 
help to derive the ratings summarized in Table 8. Temporal extent is 
not indicated in Tables 10-14 below, as it did not affect the magnitude 
rating for any applicant's specified activity.
    With regard to the duration of each estimated instance of exposure, 
we are unable to produce estimates specific to the specified activities 
due to the temporal and spatial uncertainty of vessel and cetacean 
movements within the geographic region. However, given the constant 
movement of vessels and animals, all exposures are expected to be less 
than a single day in duration. For example, based on modeling of 
similar activities in the Gulf of Mexico, we

[[Page 63365]]

assume that most instances of exposure would only last for a few 
minutes (see Table 26-27 of Zeddies et al., 2015; available online at 
www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-gulf-mexico), especially in 
the case of animals migrating through the immediate vicinity of the 
source vessel (e.g., Costa et al., 2016).

                                            Table 8--Magnitude Rating
----------------------------------------------------------------------------------------------------------------
          Amount of take                Spatial extent          Duration and frequency        Magnitude rating
----------------------------------------------------------------------------------------------------------------
High..............................  Any..................  Any............................  High.
Any except de minimis.............  High.................  Any............................  ....................
Moderate..........................  Moderate.............  Any except short-term/isolated.  ....................
Moderate..........................  Moderate.............  Short-term/isolated............  Medium.
Moderate..........................  Low..................  Any............................  ....................
Low...............................  Moderate.............  Any............................  ....................
Low...............................  Low..................  Any except short-term/           ....................
                                                            intermittent or isolated.
Low...............................  Low..................  Short-term/intermittent or       Low.
                                                            isolated.
De minimis........................  Any..................  Any............................  De minimis.
----------------------------------------------------------------------------------------------------------------
Adapted from Table 3.4 of Wood et al. (2012).

    Consequences--Considerations of amount, extent, and duration give 
an understanding of expected magnitude of effect for the stock or 
species and their habitat, which is next considered in context of the 
likely consequences of those effects for individuals. We consider 
likely relative consequences through a qualitative evaluation of 
species-specific information that helps predict the consequences of the 
information addressed through the magnitude rating, i.e., expected 
effects. The likely consequences of a given effect to individuals is 
independent of the magnitude of effect, i.e., although we recognize 
that the ultimate impact is to some degree scaled to the magnitude of 
effect, the extent to which a species is inherently vulnerable to harm 
from the effects (and therefore sensitive to magnitude) is captured by 
the ``consequences'' factor. This evaluation considers factors 
including acoustic sensitivity, communication range, known aspects of 
behavior relevant to a consideration of consequences of effects, and 
assumed compensatory abilities to engage in important behaviors (e.g., 
breeding, foraging) in alternate areas. The magnitude rating and likely 
consequences are combined to produce an ``impact rating'' (Table 9).
    For example, if a delphinid species is predicted to have a high 
amount of disturbance and over a high degree of spatial extent, that 
stock would receive a high magnitude rating for that particular survey. 
However, we may then assess that the species may have a high degree of 
compensatory ability among individuals; therefore, our conclusion would 
be that the consequences of any effects on individuals are likely low. 
The overall impact rating in this scenario would be moderate. Table 9 
summarizes impact rating scenarios.

                         Table 9--Impact Rating
------------------------------------------------------------------------
                                Consequences (for    Impact rating (for
      Magnitude rating            individuals)        species or stock)
------------------------------------------------------------------------
High........................  High/medium.........  High.
High........................  Low.................  Moderate.
Medium......................  High/medium.........  ....................
Low.........................  High................  ....................
Medium......................  Low.................  Low.
Low.........................  Medium/low..........  ....................
De minimis..................  Medium..............  ....................
De minimis..................  Low.................  De minimis.
------------------------------------------------------------------------
Adapted from Table 3.5 of Wood et al. (2012).

    Likely consequences, as presented in Tables 10-14 below, are 
considered medium for each species of mysticete whales (low-frequency 
hearing specialists), due to the greater potential for masking impacts 
at longer ranges than other taxa and at frequencies that overlap a 
larger portion of both their hearing and vocalization ranges. Likely 
consequences are considered medium for sperm whales due to potential 
for survey noise to disrupt foraging activity (e.g., Miller et al., 
2009; Farmer et al., 2018). The likely consequences are considered high 
for beaked whales due to the combination of known acoustic sensitivity 
and expected residency patterns, as we expect that compensatory ability 
for beaked whales will be low due to presumed residency in certain 
shelf break and deepwater canyon areas covered by the planned survey 
areas. Similarly, Kogia spp. are presumed to be more acoustically 
sensitive species, but unlike beaked whales we expect that Kogia spp. 
would have a reasonable compensatory ability to perform important 
behavior in alternate areas, as they are expected to occur broadly over 
the continental slope (e.g., Bloodworth and Odell, 2008)--therefore, we 
assume that consequences would be low for Kogia spp. generally. 
Consequences are also considered low for harbor porpoise; although they 
are considered to be an acoustically sensitive species and potentially 
vulnerable to limited instances of auditory injury (as are Kogia spp.), 
we have no information to suggest that porpoises are resident within 
the specific geographic region or that the expected disturbance events 
would significantly impede their ability to engage in critical 
behaviors.

[[Page 63366]]

Consequences are considered low for most delphinids, as it is unlikely 
that disturbance due to survey noise would entail significant 
disruption of normal behavioral patterns, long-term displacement, or 
significant potential for masking of acoustic space. However, for pilot 
whales we believe likely consequences to be medium due to expected 
residency in areas of importance and, therefore, lack of compensatory 
ability. Because the nature of the stressor is the same across 
applicants, we do not expect meaningful differences with regard to 
likely consequences.

Context

    In addition to our initial impact ratings, we then also consider 
additional relevant contextual factors in a qualitative fashion. This 
important consideration of context is applied to a given impact rating 
in order to produce a final assessment of impact to the stock or 
species, i.e., our negligible impact determinations. Relevant 
contextual factors include population status, other stressors 
(including impacts on prey and other habitat), and required mitigation.
    Here, we reiterate discussion relating to our development of 
targeted mitigation measures and note certain contextual factors, which 
are applicable to negligible impact analyses for all five applicants. 
Applicant-specific analyses are provided later.
     We developed mitigation requirements (i.e., time-area 
restrictions) designed specifically to provide benefit to certain 
species or stocks for which we predict a relatively moderate to high 
amount of exposure to survey noise and/or which have contextual factors 
that we believe necessitate special consideration. Time-area 
restrictions, described in detail in ``Mitigation'' and depicted in 
Figures 3-4, are designed specifically to provide benefit to the North 
Atlantic right whale, bottlenose dolphin, sperm whale, beaked whales, 
and pilot whales. In addition, we expect these areas to provide some 
subsidiary benefit to additional species that may be present. In 
particular, Area #4 (Figure 4), although delineated in order to 
specifically provide an area of anticipated benefit to beaked whales, 
sperm whales, and pilot whales, is expected to host a diverse 
assemblage of cetacean species. The output of the Roberts et al. (2016) 
models, as used in core abundance area analyses (described in detail in 
``Mitigation''), indicates that species most likely to derive 
subsidiary benefit from this time-area restriction include the 
bottlenose dolphin (offshore stock), Risso's dolphin, and common 
dolphin. For species with density predicted through stratified models, 
core abundance analysis is not possible and assumptions regarding 
potential benefit of time-area restrictions are based on known ecology 
of the species and sightings patterns and are less robust. 
Nevertheless, subsidiary benefit for Areas #1-4 (Figure 4) should be 
expected for species known to be present in these areas (e.g., assumed 
affinity for shelf/slope/abyss areas off Cape Hatteras): Kogia spp., 
pantropical spotted dolphin, Clymene dolphin, and rough-toothed 
dolphin.
    These mitigation measures benefit both the primary species for 
which they were designed and the species that may benefit secondarily 
by reducing impacts to marine mammal habitat and by reducing the 
numbers of individuals likely to be exposed to survey noise. For 
resident species in areas where seasonal closures are required, we also 
expect reduction in the numbers of times that individuals are exposed 
to survey noise (also discussed in ``Small Numbers Analyses,'' below). 
Perhaps of greater importance, we expect that these restrictions will 
reduce disturbance of these species in the places most important to 
them for critical behaviors such as foraging and socialization. Area #1 
(Figure 4), which is a year-round closure, is assumed to be an area 
important for beaked whale foraging, while Areas #2-3 (also year-round 
closures) are assumed to provide important foraging opportunities for 
sperm whales as well as beaked whales. Area #4, a seasonal closure, is 
comprised of shelf-edge habitat where beaked whales and pilot whales 
are believed to be year-round residents as well as slope and abyss 
habitat predicted to contain high abundance of sperm whales during the 
period of closure. Further detail regarding rationale for these 
closures is provided under ``Mitigation.''
     The North Atlantic right whale, sei whale, fin whale, blue 
whale, and sperm whale are listed as endangered under the Endangered 
Species Act, and all coastal stocks of bottlenose dolphin are 
designated as depleted under the MMPA (and have recently experienced an 
Unusual Mortality Event, described earlier in this document). However, 
sei whales and blue whales are unlikely to be meaningfully impacted by 
the specified activities (see ``Rare Species'' below). All four 
mysticete species are also classified as endangered (i.e., ``considered 
to be facing a very high risk of extinction in the wild'') on the 
International Union for Conservation of Nature Red List of Threatened 
Species, whereas the sperm whale is classified as vulnerable (i.e., 
``considered to be facing a high risk of extinction in the wild'') 
(IUCN, 2017). Our required mitigation is designed to avoid impacts to 
the right whale and to depleted stocks of bottlenose dolphin. Survey 
activities must avoid all areas where the right whale and coastal 
stocks of bottlenose dolphin are reasonably expected to occur (or, for 
the right whale, comparable protection would be achieved through 
implementation of a NMFS-approved mitigation and monitoring plan at 
distances between 47-80 km offshore; see ``Mitigation''), and we 
require shutdown of the acoustic source upon observation of any right 
whale at extended distance compared with the standard shutdown 
requirement. If the observed right whale is within the behavioral 
harassment zone, it would still be considered taken, but by immediately 
shutting down the acoustic source the duration of harassment is 
minimized and the significance of the harassment event reduced as much 
as possible.
    Although listed as endangered, the primary threat faced by the 
sperm whale (i.e., commercial whaling) has been eliminated and, 
further, sperm whales in the western North Atlantic were little 
affected by modern whaling (Taylor et al., 2008). Current potential 
threats to the species globally include vessel strikes, entanglement in 
fishing gear, anthropogenic noise, exposure to contaminants, climate 
change, and marine debris. However, for the North Atlantic stock, the 
most recent estimate of annual human-caused mortality and serious 
injury (M/SI) is 22 percent of the potential biological removal (PBR) 
level for the stock. As described previously, PBR is defined as ``the 
maximum number of animals, not including natural mortalities, that may 
be removed from a marine mammal stock while allowing that stock to 
reach or maintain its optimum sustainable population.'' For depleted 
stocks, levels of human-caused mortality and serious injury exceeding 
the PBR level are likely to delay restoration of the stock to OSP level 
by more than ten percent in comparison with recovery time in the 
absence of human-caused M/SI.
    The most recent status review for the species stated that existing 
regulatory mechanisms appear to minimize threats to sperm whales and 
that, despite uncertainty regarding threats such as climate change, 
contaminants, and anthropogenic noise, the significance of threat 
facing the species should be considered low to moderate (NMFS, 2015b). 
Nevertheless, existing empirical data (e.g., Miller et al., 2009; 
Farmer et al., 2018) highlight the potential for seismic survey 
activity to negatively

[[Page 63367]]

impact foraging behavior of sperm whales. In consideration of this 
likelihood, the species status, and the relatively high amount of 
predicted exposures to survey noise, we have given special 
consideration to mitigation focused on sperm whales and have defined 
time-area restrictions (see ``Mitigation'' and Figure 4) specifically 
designed to reduce such impacts on sperm whales in areas expected to be 
of greatest importance (i.e., slope habitat and deepwater canyons).
    Although the primary direct threat to fin whales was addressed 
through the moratorium on commercial whaling, vessel strike and 
entanglement in commercial fishing gear remain as substantial direct 
threats for the species in the western North Atlantic. As noted below, 
the most recent estimate of annual average human-caused mortality for 
the fin whale in U.S. waters is equal to the PBR value (Table 2). In 
addition, mysticete whales are particularly sensitive to sound in the 
frequency range output from use of airgun arrays (e.g., NMFS, 2018). 
However, there is conflicting evidence regarding the degree to which 
this sound source may significantly disrupt the behavior of mysticete 
whales. Generally speaking, mysticete whales have been observed to 
react to seismic vessels but have also been observed continuing normal 
behavior in the presence of seismic vessels, and behavioral context at 
the time of acoustic exposure may be influential in the degree to which 
whales display significant behavioral reactions. In addition, while 
Edwards et al. (2015) found that fin whales were likely present in all 
seasons in U.S. waters north of 35[deg] N, most important habitat areas 
are not expected to occur in the planned survey areas. Primary feeding 
areas are outside the project area in the Gulf of Maine and off Long 
Island (LaBrecque et al., 2015) and, while Hain et al. (1992) suggested 
that calving occurs during winter in the mid-Atlantic, Hayes et al. 
(2017) state that it is unknown where calving, mating, and wintering 
occur for most of the population. Further, fin whales are not 
considered to engage in regular mass movements along well-defined 
migratory corridors (NMFS, 2010b). The models described by Roberts et 
al. (2016), which predicted density at a monthly time step, suggest an 
expectation that, while fin whales may be present year-round in shelf 
and slope waters north of Cape Hatteras, the large majority of 
predicted abundance in U.S. waters would be found outside the planned 
survey areas to the north. Very few fin whales are likely present in 
the planned survey areas in summer months. Therefore, we have 
determined that development of time-area restriction specific to fin 
whales is not warranted. However, fin whales present along the shelf 
break north of Cape Hatteras during the closure period associated with 
Area #4 (Figure 4) would be expected to benefit from the time-area 
restriction designed primarily to benefit pilot whales, beaked whales, 
and sperm whales.
     Critical habitat is designated only for the North Atlantic 
right whale, and there are no biologically important areas (BIA) 
described within the region (other than for the right whale, and the 
described BIA is similar to designated critical habitat). Our required 
mitigation is designed to avoid impacts to important habitat for the 
North Atlantic right whale (or achieve comparable protection through 
implementation of a NMFS-approved mitigation and monitoring plan at 
distances between 47-80 km offshore; see ``Mitigation'').
     High levels of average annual human-caused M/SI 
(approaching or exceeding the PBR level) are ongoing for the North 
Atlantic right whale, sei whale, fin whale, and for both long-finned 
and short-finned pilot whales (see Table 2). Average annual M/SI is 
considered unknown for the blue whale and the false killer whale (PBR 
is undetermined for a number of other species (Table 2), but average 
annual human-caused M/SI is zero for all of these). Separately, there 
are ongoing UMEs for humpback whales and minke whales (as well as for 
the right whale), as discussed previously in this notice. Although 
threats are considered poorly known for North Atlantic blue whales, PBR 
is less than one and ship strike is a known cause of mortality for all 
mysticete whales. The most recent record of ship strike mortality for a 
blue whale in the U.S. EEZ is from 1998 (Waring et al., 2010). False 
killer whales also have a low PBR value (2.1), and may be susceptible 
to mortality in commercial fisheries. One false killer whale was 
reported as entangled in the pelagic longline fishery in 2011, but was 
released alive and not seriously injured. Separately, a stranded false 
killer whale in 2009 was classified as due to a fishery interaction. 
Incidental take of the sei whale, blue whale, false killer whale, and 
long-finned pilot whale is considered unlikely and we authorize take by 
behavioral harassment only for a single group of each of the first 
three species as a precaution. Although long-finned pilot whales are 
unlikely to occur in the action area in significant numbers, the 
density models that inform our exposure estimates consider pilot whales 
as a guild. It is important to note that our discussion of M/SI in 
relation to PBR values provides necessary contextual information 
related to the status of stocks; we do not equate harassment with M/SI.
    We addressed our consideration of specific mitigation efforts for 
the right whale and fin whale above. For minke whales, although the 
ongoing UME is under investigation (as occurs for all UMEs), this event 
does not provide cause for concern regarding population-level impacts, 
as the likely population abundance is greater than 20,000 whales. Even 
though the PBR value is based on an abundance for U.S. waters that is 
negatively biased and a small fraction of the true population 
abundance, annual M/SI does not exceed the calculated PBR value for 
minke whales.
    With regard to humpback whales, the UME does not yet provide cause 
for concern regarding population-level impacts. Despite the UME, the 
relevant population of humpback whales (the West Indies breeding 
population, or distinct population segment (DPS)) remains healthy. 
Prior to 2016, humpback whales were listed under the ESA as an 
endangered species worldwide. Following a 2015 global status review 
(Bettridge et al., 2015), NMFS established 14 DPSs with different 
listing statuses (81 FR 62259; September 8, 2016) pursuant to the ESA. 
The West Indies DPS, which consists of the whales whose breeding range 
includes the Atlantic margin of the Antilles from Cuba to northern 
Venezuela, and whose feeding range primarily includes the Gulf of 
Maine, eastern Canada, and western Greenland, was delisted. The status 
review identified harmful algal blooms, vessel collisions, and fishing 
gear entanglements as relevant threats for this DPS, but noted that all 
other threats are considered likely to have no or minor impact on 
population size or the growth rate of this DPS (Bettridge et al., 
2015). As described in Bettridge et al. (2015), the West Indies DPS has 
a substantial population size (i.e., approximately 10,000; Stevick et 
al., 2003; Smith et al., 1999; Bettridge et al., 2015), and appears to 
be experiencing consistent growth.
    In response to this population context concern for pilot whales, in 
conjunction with relatively medium to high amount of predicted 
exposures to survey noise for pilot whales, we have given special 
consideration to mitigation focused on pilot whales and have defined 
time-area restrictions (see ``Mitigation'' and Figure 4) specifically 
designed to reduce such impacts on pilot whales in areas

[[Page 63368]]

expected to be of greatest importance (i.e., shelf edge north of Cape 
Hatteras).
     Beaked whales are considered to be particularly 
acoustically sensitive (e.g., Tyack et al., 2011; DeRuiter et al., 
2013; Stimpert et al., 2014; Miller et al., 2015). Considering this 
sensitivity in conjunction with the relatively high amount of predicted 
exposures to survey noise, we have given special consideration to 
mitigation focused on beaked whales and have defined time-area 
restrictions (see ``Mitigation'' and Figure 4) specifically designed to 
reduce such impacts on beaked whales in areas expected to be of 
greatest importance (i.e., shelf edge south of Cape Hatteras and 
deepwater canyon areas).
     Given the current declining population status of North 
Atlantic right whales, it is important to understand the likely 
demographics of the expected taking. Therefore, we obtained data from 
the North Atlantic Right Whale Consortium Database (pers. comm., T.A. 
Gowan to E. Patterson, November 8, 2017), consisting of standardized 
sighting records of right whales from 2005 to 2013 from South Carolina 
to Florida. Because of the low total number of expected exposure for 
right whales, we could not reasonably apply this information on an 
applicant-specific basis and therefore present these findings for the 
total expected taking across all applicants. Based on this information, 
of the total 23 takes of North Atlantic right whales (now revised 
downward to 19 takes on the basis of Spectrum's modified survey plan; 
see ``Spectrum Survey Plan Modification''), it should be expected that 
four exposures could be of adult females with calves, two of adult 
females without calves, five of adult males, 11 of juveniles of either 
sex, three of calves of either sex, one of an adult of unknown sex, and 
two of animals of unknown age and sex. It is important to note that age 
class estimates sum to greater than the originally expected total of 23 
due to conservative rounding up in presenting the maximum number of 
each age-sex class that might be exposed; this should not be construed 
as an assumption that there would be more total takes of right whales 
than are authorized across all applicants. Each of these exposures 
represents a single instance of Level B harassment and is therefore not 
considered as a meaningful impact to individuals that could lead to 
population-level impacts.

Rare Species

    As described previously, there are multiple species that should be 
considered rare in the survey areas and for which we authorize only 
nominal and precautionary take of a single group for each applicant 
survey. Specific to each of the five applicant companies, we do not 
expect meaningful impacts to these species (i.e., sei whale, Bryde's 
whale, blue whale, killer whale, false killer whale, pygmy killer 
whale, melon-headed whale, northern bottlenose whale, spinner dolphin, 
Fraser's dolphin, Atlantic white-sided dolphin) and find that the take 
from each of the specified activities will have a negligible impact on 
these marine mammal species. We do not discuss these 11 species further 
in these analyses.

Spectrum

    Spectrum originally planned a 165-day survey program, or 45 percent 
of the year (approximately two seasons). The original survey plan would 
cover a large spatial extent (i.e., a majority of the mid- and south 
Atlantic; see Figure 1 of Spectrum's application). Therefore, although 
that survey would be long-term (i.e., greater than one season) in total 
duration, we would not expect the duration of effect to be greater than 
moderate and intermittent in any given area. Table 10 displays relevant 
information leading to impact ratings for each species resulting from 
Spectrum's original survey plan. In general, we note that although the 
temporal and spatial scale of the planned survey activity is large, it 
is not occupying the spatial extent all at one time. The fact that this 
mobile acoustic source would be moving across large areas (as compared 
with geophysical surveys with different objectives that may require 
focused effort over long periods of time in smaller areas) means that 
more individuals may receive limited exposure to survey noise, versus 
fewer individuals receiving more intense exposure and/or for longer 
periods of time. The nature of such potentially transitory exposure 
(which we nevertheless assume here is of moderate duration and 
intermittent, versus isolated) means that the potential significance of 
behavioral disruption and potential for longer-term avoidance of 
important areas is limited. Please see ``Spectrum Survey Plan 
Modification,'' below, for additional information describing the 
modified survey plan, findings made in context of the analysis 
presented below, and authorized take for Spectrum (Table 17).

                                                    Table 10--Magnitude and Impact Ratings, Spectrum
--------------------------------------------------------------------------------------------------------------------------------------------------------
              Species                        Amount              Spatial extent         Magnitude rating         Consequences        Impact rating \1\
--------------------------------------------------------------------------------------------------------------------------------------------------------
North Atlantic right whale.........  De minimis............  Low-Moderate..........  De minimis...........  Medium...............  Low.
Humpback whale.....................  De minimis............  Low-Moderate..........  De minimis...........  Medium...............  Low.
Minke whale........................  De minimis............  Low-High..............  De minimis...........  Medium...............  Low.
Fin whale..........................  Low...................  Low...................  Medium...............  Medium...............  Moderate.
Sperm whale........................  Low...................  Moderate..............  Medium...............  Medium...............  Moderate.
Kogia spp..........................  Low...................  High..................  High.................  Low..................  Moderate.
Beaked whales......................  Low...................  Moderate..............  Medium...............  High.................  Moderate.
Rough-toothed dolphin..............  Moderate..............  High..................  High.................  Low..................  Moderate.
Bottlenose dolphin.................  High..................  High..................  High.................  Low..................  Moderate.
Clymene dolphin....................  High..................  High..................  High.................  Low..................  Moderate.
Atlantic spotted dolphin...........  Moderate..............  Moderate..............  High.................  Low..................  Moderate.
Pantropical spotted dolphin........  Moderate..............  High..................  High.................  Low..................  Moderate.
Striped dolphin....................  Low...................  Low...................  Medium...............  Low..................  Low.
Common dolphin.....................  Low...................  Low-moderate..........  Medium...............  Low..................  Low.
Risso's dolphin....................  De minimis............  Low-moderate..........  De minimis...........  Low..................  De minimus.
Pilot whales.......................  Low...................  Moderate..............  Medium...............  Medium...............  Moderate.
Harbor porpoise....................  De minimis............  Low...................  De minimis...........  Low..................  De minimis.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Impact rating does not indicate whether overall impact to the species or stock is negligible, but is considered with relevant contextual factors
  (described generally above and specifically below) in order to ultimately determine whether the effects of the specified activity on the affected
  species or stock are negligible.


[[Page 63369]]

    The North Atlantic right whale is endangered, has a very low 
population size, and faces significant additional stressors. Therefore, 
regardless of even a low impact rating, we believe that the required 
mitigation described previously is critically important in order for us 
to make the necessary finding and it is with consideration of this 
mitigation that we find the take from Spectrum's survey activities will 
have a negligible impact on the North Atlantic right whale. The fin 
whale receives a moderate impact rating overall, but we expect that for 
two seasons (summer and fall) almost no fin whales will be present in 
the survey area. For the remainder of the year, it is likely that less 
than one quarter of the population will be present within the survey 
area (Roberts et al., 2016), meaning that despite medium rankings for 
magnitude and likely consequences, these impacts would be experienced 
by only a small subset of the overall population. In consideration of 
the moderate impact rating, the likely proportion of the population 
that may be affected by the specified activities, and the lack of 
evidence that the survey area is host to important behaviors that may 
be disrupted, we find the take from Spectrum's survey activities will 
have a negligible impact on the fin whale.
    Magnitude ratings for the sperm whale and beaked whales are medium; 
however, consequence factors are medium and high, respectively. 
Magnitude rating for pilot whales is medium, but similar to beaked 
whales, we expect that compensatory ability will be low (high 
consequence rating) due to presumed residency in areas targeted by the 
planned survey. These factors lead to moderate impact ratings for all 
three species/species groups. However, regardless of impact rating, the 
consideration of likely consequences and contextual factors for all 
three taxa leads us to conclude that targeted mitigation is important 
to support a finding that the effects of the survey will have a 
negligible impact on these species. As described previously, sperm 
whales are an endangered species with particular susceptibility to 
disruption of foraging behavior, beaked whales are particularly 
acoustically sensitive (with presumed low compensatory ability), and 
pilot whales are sensitive to additional stressors due to a high degree 
of mortality in commercial fisheries (and also with low compensatory 
ability). Finally, due to their acoustic sensitivity, we require 
shutdown of the acoustic source upon detection of a beaked whale at 
extended distance from the source vessel. In consideration of the 
required mitigation, we find the take from Spectrum's survey activities 
will have a negligible impact on the sperm whale, beaked whales (i.e., 
Ziphius cavirostris and Mesoplodon spp.), and pilot whales (i.e., 
Globicephala spp.).
    Kogia spp. receive a moderate impact rating. However, although NMFS 
does not currently identify a trend for these populations, recent 
survey effort and stranding data show a simultaneous increase in at-sea 
abundance and strandings, suggesting growing Kogia spp. abundance 
(NMFS, 2011; 2013a; Waring et al., 2007; 2013). Finally, we expect that 
Kogia spp. will receive subsidiary benefit from the required mitigation 
targeted for sperm whales, beaked whales, and pilot whales and, 
although minimally effective due to the difficulty of at-sea 
observation of Kogia spp., we require shutdown of the acoustic source 
upon observation of Kogia spp. at extended distance from the source 
vessel. In consideration of these factors--likely population increase 
and required mitigation--we find the take from Spectrum's survey 
activities will have a negligible impact on Kogia spp.
    As described in the introduction to this analysis, it is assumed 
that likely consequences are somewhat higher for species of mysticete 
whales (low-frequency hearing specialists) due to the greater potential 
for masking impacts at longer ranges than other taxa and at frequencies 
that overlap a larger portion of both their hearing and vocalization 
ranges. Therefore, despite de minimis magnitude ratings, we expect some 
consequences to individual humpback and minke whales, i.e., leading to 
a low impact rating. However, given the minimal amount of interaction 
expected between these species and the survey activities, and in 
consideration of the overall low impact ratings, we find the take from 
Spectrum's planned survey activities will have a negligible impact on 
the humpback whale and minke whale.
    Despite medium to high magnitude ratings, remaining delphinid 
species receive low to moderate impact ratings due to low consequences 
rating relating to a lack of propensity for behavioral disruption due 
to airgun survey activity and our expectation that these species would 
generally have relatively high compensatory ability. In addition, 
contextually these species do not have significant issues relating to 
population status or context. Many oceanic delphinid species are 
generally more associated with dynamic oceanographic characteristics 
rather than static physical features, and those species (such as common 
dolphin) with substantial distribution to the north of the survey area 
would likely be little affected at the population level by the 
activity. For example, both species of spotted dolphin and the offshore 
stock of bottlenose dolphin range widely over slope and abyssal waters 
(e.g., Waring et al., 2014; Hayes et al., 2017; Roberts et al., 2016), 
while the rough-toothed dolphin does not appear bound by water depth in 
its range (Ritter, 2002; Wells et al., 2008). Our required mitigation 
largely eliminates potential effects to depleted coastal stocks of 
bottlenose dolphin. We also expect that meaningful subsidiary benefit 
will accrue to certain species from the mitigation targeted for sperm 
whales, beaked whales, and pilot whales, most notably to species 
presumed to have greater association with shelf break waters north of 
Cape Hatteras (e.g., offshore bottlenose dolphins, common dolphins, and 
Risso's dolphins). In consideration of these factors--overall impact 
ratings and context including required mitigation--we find the take 
from Spectrum's planned survey activities will have a negligible impact 
on remaining delphinid species (i.e., all stocks of bottlenose dolphin, 
two species of spotted dolphin, rough-toothed dolphin, striped dolphin, 
common dolphin, and Clymene dolphin).
    For those species with de minimis impact ratings we believe that, 
absent additional relevant concerns related to population status or 
context, the rating implies that a negligible impact should be expected 
as a result of the specified activity. No such concerns exist for these 
species, and we find the take from Spectrum's survey activities will 
have a negligible impact on the Risso's dolphin and harbor porpoise.
    In summary, based on the analysis contained herein of the likely 
effects of the specified activity on marine mammals and their habitat, 
and taking into consideration the implementation of the required 
monitoring and mitigation measures, we find that the total marine 
mammal take from Spectrum's survey activities will have a negligible 
impact on all affected marine mammal species or stocks.
    TGS--TGS has planned a 308-day survey program, or 84 percent of the 
year (slightly more than three seasons). However, the planned survey 
would cover a large spatial extent (i.e., a majority of the mid- and 
south Atlantic; see Figures 1-1 to 1-4 of TGS's application). 
Therefore, although the survey would be long-term (i.e., greater than 
one season) in total duration, we would not expect the duration of 
effect to be greater than moderate and intermittent in any given area. 
We note

[[Page 63370]]

that TGS plans to deploy two independent source vessels, which would in 
effect increase the spatial extent of survey noise at any one time but, 
because the vessels would not be operating within the same area or 
reshooting lines already covered, this would not be expected to 
increase the duration or frequency of exposure experienced by 
individual animals. Table 11 displays relevant information leading to 
impact ratings for each species resulting from TGS's survey. In 
general, we note that although the temporal and spatial scale of the 
planned survey activity is large, the fact that these mobile acoustic 
sources would be moving across large areas (as compared with 
geophysical surveys with different objectives that may require focused 
effort over long periods of time in smaller areas) means that more 
individuals may receive limited exposure to survey noise, versus fewer 
individuals receiving more intense exposure and/or for longer periods 
of time. The nature of such potentially transitory exposure (which we 
nevertheless assume here is of moderate duration and intermittent, 
versus isolated) means that the potential significance of behavioral 
disruption and potential for longer-term avoidance of important areas 
is limited.

                                                       Table 11--Magnitude and Impact Ratings, TGS
--------------------------------------------------------------------------------------------------------------------------------------------------------
              Species                        Amount              Spatial extent         Magnitude rating         Consequences        Impact rating \1\
--------------------------------------------------------------------------------------------------------------------------------------------------------
North Atlantic right whale.........  De minimis............  Low-Moderate..........  De minimis...........  Medium...............  Low.
Humpback whale.....................  De minimis............  Low-Moderate..........  De minimis...........  Medium...............  Low.
Minke whale........................  De minimis............  Low-High..............  De minimis...........  Medium...............  Low.
Fin whale..........................  Moderate..............  Low...................  Medium...............  Medium...............  Moderate.
Sperm whale........................  High..................  Moderate..............  High.................  Medium...............  High.
Kogia spp..........................  High..................  High..................  High.................  Low..................  Moderate.
Beaked whales......................  High..................  Moderate..............  High.................  High.................  High.
Rough-toothed dolphin..............  High..................  High..................  High.................  Low..................  Moderate.
Bottlenose dolphin.................  High..................  High..................  High.................  Low..................  Moderate.
Clymene dolphin....................  De minimis............  High..................  De minimis...........  Low..................  De minimis.
Atlantic spotted dolphin...........  High..................  Moderate..............  High.................  Low..................  Moderate.
Pantropical spotted dolphin........  Moderate..............  High..................  High.................  Low..................  Moderate.
Striped dolphin....................  Low...................  Low...................  Medium...............  Low..................  Low.
Common dolphin.....................  High..................  Low-moderate..........  High.................  Low..................  Moderate.
Risso's dolphin....................  Moderate..............  Low-moderate..........  High.................  Low..................  Moderate.
Pilot whales.......................  High..................  Moderate..............  High.................  Medium...............  High.
Harbor porpoise....................  De minimis............  Low...................  De minimis...........  Low..................  De minimis.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Impact rating does not indicate whether overall impact to the species or stock is negligible, but is considered with relevant contextual factors
  (described generally above and specifically below) in order to ultimately determine whether the effects of the specified activity on the affected
  species or stock are negligible.

    The North Atlantic right whale is endangered, has a very low 
population size, and faces significant additional stressors. Therefore, 
regardless of even a low impact rating, we believe that the required 
mitigation described previously is critically important in order for us 
to make the necessary finding and it is with consideration of this 
mitigation that we find the take from TGS's survey activities will have 
a negligible impact on the North Atlantic right whale. The fin whale 
receives a moderate impact rating overall, but we expect that for two 
seasons (summer and fall) almost no fin whales will be present in the 
survey area. For the remainder of the year, it is likely that less than 
one quarter of the population will be present within the survey area 
(Roberts et al., 2016), meaning that despite medium rankings for 
magnitude and likely consequences, these impacts would be experienced 
by only a small subset of the overall population. In consideration of 
the moderate impact rating, the likely proportion of the population 
that may be affected by the specified activities, and the lack of 
evidence that the survey area is host to important behaviors that may 
be disrupted, we find the take from TGS's survey activities will have a 
negligible impact on the fin whale.
    Magnitude ratings for the sperm whale, beaked whales, and pilot 
whales are high and, further, consequence factors reinforce high impact 
ratings for all three. In addition, the consideration of likely 
consequences and contextual factors leads us to conclude that targeted 
mitigation is important to support a finding that the effects of the 
survey will have a negligible impact on these species. As described 
previously, sperm whales are an endangered species with particular 
susceptibility to disruption of foraging behavior, beaked whales are 
particularly acoustically sensitive (with presumed low compensatory 
ability and, therefore, high consequence rating), and pilot whales are 
sensitive to additional stressors due to a high degree of mortality in 
commercial fisheries (and also with low compensatory ability). Finally, 
due to their acoustic sensitivity, we have required shutdown of the 
acoustic source upon observation of a beaked whale at extended distance 
from the source vessel. In consideration of the required mitigation, we 
find the take from TGS's survey activities will have a negligible 
impact on the sperm whale, beaked whales (i.e., Ziphius cavirostris and 
Mesoplodon spp.), and pilot whales (i.e., Globicephala spp.).
    Kogia spp. receive a moderate impact rating. However, although NMFS 
does not currently identify a trend for these populations, recent 
survey effort and stranding data show a simultaneous increase in at-sea 
abundance and strandings, suggesting growing Kogia spp. abundance 
(NMFS, 2011; 2013a; Waring et al., 2007; 2013). Finally, we expect that 
Kogia spp. will receive subsidiary benefit from the mitigation targeted 
for sperm whales, beaked whales, and pilot whales and, although 
minimally effective due to the difficulty of at-sea observation of 
Kogia spp., we have required shutdown of the acoustic source upon 
observation of Kogia spp. at extended distance from the source vessel. 
In consideration of these factors--likely population increase and 
required mitigation--we find the take from TGS's survey activities will 
have a negligible impact on Kogia spp.
    As described in the introduction to this analysis, it is assumed 
that likely consequences are somewhat higher for

[[Page 63371]]

species of mysticete whales (low-frequency hearing specialists) due to 
the greater potential for masking impacts at longer ranges than other 
taxa and at frequencies that overlap a larger portion of both their 
hearing and vocalization ranges. Therefore, despite de minimis 
magnitude ratings, we expect some consequences to individual humpback 
and minke whales, i.e., leading to a low impact rating. However, given 
the minimal amount of interaction expected between these species and 
the survey activities, and in consideration of the overall low impact 
ratings, we find the take from TGS's planned survey activities will 
have a negligible impact on the humpback whale and minke whale.
    Despite high magnitude ratings, most remaining delphinid species 
receive moderate impact ratings (with the exception of the striped 
dolphin, with medium magnitude rating and low impact rating), due to 
low consequences rating relating to a lack of propensity for behavioral 
disruption due to airgun survey activity and our expectation that these 
species would generally have relatively high compensatory ability. In 
addition, contextually these species do not have significant issues 
relating to population status or context. Many oceanic delphinid 
species are generally more associated with dynamic oceanographic 
characteristics rather than static physical features, and those species 
(such as common dolphin) with substantial distribution to the north of 
the survey area would likely be little affected at the population level 
by the specified activity. For example, both species of spotted dolphin 
and the offshore stock of bottlenose dolphin range widely over slope 
and abyssal waters (e.g., Waring et al., 2014; Hayes et al., 2017; 
Roberts et al., 2016), while the rough-toothed dolphin does not appear 
bound by water depth in its range (Ritter, 2002; Wells et al., 2008). 
Our required mitigation largely eliminates potential effects to 
depleted coastal stocks of bottlenose dolphin. We also expect that 
meaningful subsidiary benefit will accrue to certain species from the 
mitigation targeted for sperm whales, beaked whales, and pilot whales, 
most notably to species presumed to have greater association with shelf 
break waters north of Cape Hatteras (e.g., offshore bottlenose 
dolphins, common dolphins, and Risso's dolphins). In consideration of 
these factors--overall impact ratings and context including required 
mitigation--we find the take from TGS's survey activities will have a 
negligible impact on most remaining delphinid species (i.e., all stocks 
of bottlenose dolphin, two species of spotted dolphin, rough-toothed 
dolphin, striped dolphin, common dolphin, and Risso's dolphin).
    For those species with de minimis impact ratings we believe that, 
absent additional relevant concerns related to population status or 
context, the rating implies that a negligible impact should be expected 
as a result of the specified activity. No such concerns exist for these 
species, and we find the take from TGS's survey activities will have a 
negligible impact on the Clymene dolphin and harbor porpoise.
    In summary, based on the analysis contained herein of the likely 
effects of the specified activity on marine mammals and their habitat, 
and taking into consideration the implementation of the required 
monitoring and mitigation measures, we find that the total marine 
mammal take from TGS's survey activities will have a negligible impact 
on all affected marine mammal species or stocks.
    ION--ION has planned a 70-day survey program, or 19 percent of the 
year (slightly less than one season). However, the planned survey would 
cover a large spatial extent (i.e., a majority of the mid- and south 
Atlantic; see Figure 1 of ION's application). Therefore, although the 
survey would be moderate-term (i.e., from 1-3 months) in total 
duration, we would not expect the duration of effect to be greater than 
short and isolated to intermittent in any given area. Table 12 displays 
relevant information leading to impact ratings for each species 
resulting from ION's survey. In general, we note that although the 
temporal and spatial scale of the planned survey activity is large, the 
fact that this mobile acoustic source would be moving across large 
areas (as compared with geophysical surveys with different objectives 
that may require focused effort over long periods of time in smaller 
areas) means that more individuals may receive limited exposure to 
survey noise, versus fewer individuals receiving more intense exposure 
and/or for longer periods of time. The nature of such potentially 
transitory exposure means that the potential significance of behavioral 
disruption and potential for longer-term avoidance of important areas 
is limited.

                                                       Table 12--Magnitude and Impact Ratings, ION
--------------------------------------------------------------------------------------------------------------------------------------------------------
              Species                        Amount              Spatial extent         Magnitude rating         Consequences        Impact rating \1\
--------------------------------------------------------------------------------------------------------------------------------------------------------
North Atlantic right whale.........  De minimis............  Low-Moderate..........  De minimis...........  Medium...............  Low.
Humpback whale.....................  De minimis............  Low-Moderate..........  De minimis...........  Medium...............  Low.
Minke whale........................  De minimis............  Low-High..............  De minimis...........  Medium...............  Low.
Fin whale..........................  De minimis............  Low...................  De minimis...........  Medium...............  Low.
Sperm whale........................  De minimis............  Moderate..............  De minimis...........  Medium...............  Low.
Kogia spp..........................  De minimis............  High..................  De minimis...........  Low..................  De minimis.
Beaked whales......................  De minimis............  Moderate..............  De minimis...........  High.................  Low.
Rough-toothed dolphin..............  De minimis............  High..................  De minimis...........  Low..................  De minimis.
Bottlenose dolphin.................  De minimis............  High..................  De minimis...........  Low..................  De minimis.
Clymene dolphin....................  De minimis............  High..................  De minimis...........  Low..................  De minimis.
Atlantic spotted dolphin...........  De minimis............  Moderate..............  De minimis...........  Low..................  De minimis.
Pantropical spotted dolphin........  De minimis............  High..................  De minimis...........  Low..................  De minimis.
Striped dolphin....................  De minimis............  Low...................  De minimis...........  Low..................  De minimis.
Common dolphin.....................  De minimis............  Low-moderate..........  De minimis...........  Low..................  De minimis.
Risso's dolphin....................  De minimis............  Low-moderate..........  De minimis...........  Low..................  De minimis.
Pilot whales.......................  De minimis............  Moderate..............  De minimis...........  Medium...............  Low.
Harbor porpoise....................  De minimis............  Low...................  De minimis...........  Low..................  De minimis.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Impact rating does not indicate whether overall impact to the species or stock is negligible, but is considered with relevant contextual factors
  (described generally above and specifically below) in order to ultimately determine whether the effects of the specified activity on the affected
  species or stock are negligible.


[[Page 63372]]

    The North Atlantic right whale is endangered, has a very low 
population size, and faces significant additional stressors. Therefore, 
regardless of impact rating, we believe that the required mitigation 
described previously is critically important in order for us to make 
the necessary finding and it is with consideration of this mitigation 
that we find the take from ION's planned survey activities will have a 
negligible impact on the North Atlantic right whale.
    Also regardless of impact rating, consideration of assumed 
behavioral susceptibility and lack of compensatory ability (i.e., 
consequence factors) as well as additional contextual factors leads us 
to conclude that the required targeted time-area mitigation described 
previously is important to support a finding that the effects of the 
planned survey will have a negligible impact for the sperm whale, 
beaked whales (i.e., Ziphius cavirostris and Mesoplodon spp.), and 
pilot whales (i.e., Globicephala spp.). As described previously, sperm 
whales are an endangered species with particular susceptibility to 
disruption of foraging behavior, beaked whales are particularly 
acoustically sensitive, and pilot whales are sensitive to additional 
stressors due to a high degree of mortality in commercial fisheries. 
Further, we expect that compensatory ability for beaked whales will be 
low due to presumed residency in certain shelf break and deepwater 
canyon areas covered by the survey area and that compensatory ability 
for pilot whales will also be low due to presumed residency in areas 
targeted by the planned survey (when compensatory ability is assumed to 
be low, we assign a high consequence factor). Kogia spp. are also 
considered to have heightened acoustic sensitivity and therefore we 
have required shutdown of the acoustic source upon observation of a 
beaked whale or a Kogia spp. at extended distance from the source 
vessel. In consideration of the required mitigation, we find the take 
from ION's survey activities will have a negligible impact on the sperm 
whale, beaked whales, pilot whales, and Kogia spp.
    As described in the introduction to this analysis, it is assumed 
that likely consequences are somewhat higher for species of mysticete 
whales (low-frequency hearing specialists) due to the greater potential 
for masking impacts at longer ranges than other taxa and at frequencies 
that overlap a larger portion of both their hearing and vocalization 
ranges. Therefore, despite de minimis magnitude ratings, we expect some 
consequences to individual humpback, fin, and minke whales, i.e., 
leading to a low impact rating. However, given the minimal amount of 
interaction expected between these species and the survey activities, 
and in consideration of the overall low impact ratings, we find the 
take from ION's planned survey activities will have a negligible impact 
on the humpback whale, fin whale, and minke whale.
    For those species with de minimis impact ratings we believe that, 
absent additional relevant concerns related to population status or 
context, the rating implies that a negligible impact should be expected 
as a result of the specified activity. No such concerns exist for these 
species, and we find the take from ION's planned survey activities will 
have a negligible impact on all stocks of bottlenose dolphin, two 
species of spotted dolphin, rough-toothed dolphin, striped dolphin, 
common dolphin, Clymene dolphin, Risso's dolphin, and harbor porpoise.
    In summary, based on the analysis contained herein of the likely 
effects of the specified activity on marine mammals and their habitat, 
and taking into consideration the implementation of the required 
monitoring and mitigation measures, we find that the total marine 
mammal take from ION's survey activities will have a negligible impact 
on all affected marine mammal species or stocks.
    Western--Western has planned a 208-day survey program, or 57 
percent of the year (slightly more than two seasons). However, the 
planned survey would cover a large spatial extent (i.e., a majority of 
the mid- and south Atlantic; see Figures 1-1 to 1-4 of Western's 
application). Therefore, although the survey would be long-term (i.e., 
greater than one season) in total duration, we would not expect the 
duration of effect to be greater than moderate and intermittent in any 
given area. Table 13 displays relevant information leading to impact 
ratings for each species resulting from Western's survey. In general, 
we note that although the temporal and spatial scale of the planned 
survey activity is large, the fact that this mobile acoustic source 
would be moving across large areas (as compared with geophysical 
surveys with different objectives that may require focused effort over 
long periods of time in smaller areas) means that more individuals may 
receive limited exposure to survey noise, versus fewer individuals 
receiving more intense exposure and/or for longer periods of time. The 
nature of such potentially transitory exposure (which we nevertheless 
assume here is of moderate duration and intermittent, versus isolated) 
means that the potential significance of behavioral disruption and 
potential for longer-term avoidance of important areas is limited.

                                                     Table 13--Magnitude and Impact Ratings, Western
--------------------------------------------------------------------------------------------------------------------------------------------------------
              Species                        Amount              Spatial extent         Magnitude rating         Consequences        Impact rating \1\
--------------------------------------------------------------------------------------------------------------------------------------------------------
North Atlantic right whale.........  De minimis............  Low-Moderate..........  De minimis...........  Medium...............  Low.
Humpback whale.....................  De minimis............  Low-Moderate..........  De minimis...........  Medium...............  Low.
Minke whale........................  De minimis............  Low-High..............  De minimis...........  Medium...............  Low.
Fin whale..........................  Low...................  Low...................  Medium...............  Medium...............  Moderate.
Sperm whale........................  Moderate..............  Moderate..............  High.................  Medium...............  High.
Kogia spp..........................  Moderate..............  High..................  High.................  Low..................  Moderate.
Beaked whales......................  Moderate..............  Moderate..............  High.................  High.................  High.
Rough-toothed dolphin..............  Low...................  High..................  High.................  Low..................  Moderate.
Bottlenose dolphin.................  Moderate..............  High..................  High.................  Low..................  Moderate.
Clymene dolphin....................  De minimis............  High..................  De minimis...........  Low..................  De minimis.
Atlantic spotted dolphin...........  Moderate..............  Moderate..............  High.................  Low..................  Moderate.
Pantropical spotted dolphin........  Low...................  High..................  High.................  Low..................  Moderate.
Striped dolphin....................  Low...................  Low...................  Medium...............  Low..................  Low.
Common dolphin.....................  Low...................  Low-moderate..........  Medium...............  Low..................  Low.
Risso's dolphin....................  Low...................  Low-moderate..........  Medium...............  Low..................  Low.
Pilot whales.......................  Low...................  Moderate..............  Medium...............  Medium...............  Moderate.

[[Page 63373]]

 
Harbor porpoise....................  De minimis............  Low...................  De minimis...........  Low..................  De minimis
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Impact rating does not indicate whether overall impact to the species or stock is negligible, but is considered with relevant contextual factors
  (described generally above and specifically below) in order to ultimately determine whether the effects of the specified activity on the affected
  species or stock are negligible.

    The North Atlantic right whale is endangered, has a very low 
population size, and faces significant additional stressors. Therefore, 
regardless of impact rating, we believe that the required mitigation 
described previously is critically important in order for us to make 
the necessary finding and it is with consideration of this mitigation 
that we find the take from Western's survey activities will have a 
negligible impact on the North Atlantic right whale. The fin whale 
receives a moderate impact rating overall, but we expect that for two 
seasons (summer and fall) almost no fin whales will be present in the 
survey area. For the remainder of the year, it is likely that less than 
one quarter of the population will be present within the survey area 
(Roberts et al., 2016), meaning that despite medium rankings for 
magnitude and likely consequences, these impacts would be experienced 
by only a small subset of the overall population. In consideration of 
the moderate impact rating, the likely proportion of the population 
that may be affected by the specified activities, and the lack of 
evidence that the survey area is host to important behaviors that may 
be disrupted, we find the take from Western's survey activities will 
have a negligible impact on the fin whale.
    Magnitude ratings for the sperm whale and beaked whales are high 
and, further, consequence factors reinforce high impact ratings for 
both. Magnitude rating for pilot whales is medium but, similar to 
beaked whales, we expect that compensatory ability will be low (high 
consequence rating) due to presumed residency in areas targeted by the 
planned survey--leading to a moderate impact rating. However, 
regardless of impact rating, the consideration of likely consequences 
and contextual factors for all three taxa leads us to conclude that 
targeted mitigation is important to support a finding that the effects 
of the survey will have a negligible impact on these species. As 
described previously, sperm whales are an endangered species with 
particular susceptibility to disruption of foraging behavior, beaked 
whales are particularly acoustically sensitive (with presumed low 
compensatory ability), and pilot whales are sensitive to additional 
stressors due to a high degree of mortality in commercial fisheries 
(and also with low compensatory ability). Finally, due to their 
acoustic sensitivity, we have required shutdown of the acoustic source 
upon observation of a beaked whale at extended distance from the source 
vessel. In consideration of the required mitigation, we find the take 
from Western's survey activities will have a negligible impact on the 
sperm whale, beaked whales (i.e., Ziphius cavirostris and Mesoplodon 
spp.), and pilot whales (i.e., Globicephala spp.).
    Kogia spp. receive a moderate impact rating. However, although NMFS 
does not currently identify a trend for these populations, recent 
survey effort and stranding data show a simultaneous increase in at-sea 
abundance and strandings, suggesting growing Kogia spp. abundance 
(NMFS, 2011; 2013a; Waring et al., 2007; 2013). Finally, we expect that 
Kogia spp. will receive subsidiary benefit from the mitigation targeted 
for sperm whales, beaked whales, and pilot whales and, although 
minimally effective due to the difficulty of at-sea observation of 
Kogia spp., we have required shutdown of the acoustic source upon 
observation of Kogia spp. at extended distance from the source vessel. 
In consideration of these factors--likely population increase and 
required mitigation--we find the take from Western's survey activities 
will have a negligible impact on Kogia spp.
    As described in the introduction to this analysis, it is assumed 
that likely consequences are somewhat higher for species of mysticete 
whales (low-frequency hearing specialists) due to the greater potential 
for masking impacts at longer ranges than other taxa and at frequencies 
that overlap a larger portion of both their hearing and vocalization 
ranges. Therefore, despite de minimis magnitude ratings, we expect some 
consequences to individual humpback and minke whales, i.e., leading to 
a low impact rating. However, given the minimal amount of interaction 
expected between these species and the survey activities, and in 
consideration of the overall low impact ratings, we find the take from 
Western's planned survey activities will have a negligible impact on 
the humpback whale and minke whale.
    Despite medium to high magnitude ratings (with the exception of the 
Clymene dolphin), remaining delphinid species receive low to moderate 
impact ratings due to consequences relating to a lack of propensity for 
behavioral disruption due to airgun survey activity and our expectation 
that these species would generally have relatively high compensatory 
ability. In addition, contextually these species do not have 
significant issues relating to population status or context. Many 
oceanic delphinid species are generally more associated with dynamic 
oceanographic characteristics rather than static physical features, and 
those species (such as common dolphin) with substantial distribution to 
the north of the survey area would likely be little affected at the 
population level by the specified activity. For example, both species 
of spotted dolphin and the offshore stock of bottlenose dolphin range 
widely over slope and abyssal waters (e.g., Waring et al., 2014; Hayes 
et al., 2017; Roberts et al., 2016), while the rough-toothed dolphin 
does not appear bound by water depth in its range (Ritter, 2002; Wells 
et al., 2008). Our required mitigation largely eliminates potential 
effects to depleted coastal stocks of bottlenose dolphin. We also 
expect that meaningful subsidiary benefit will accrue to certain 
species from the mitigation targeted for sperm whales, beaked whales, 
and pilot whales, most notably to species presumed to have greater 
association with shelf break waters north of Cape Hatteras (e.g., 
offshore bottlenose dolphins, common dolphins, and Risso's dolphins). 
In consideration of these factors--overall impact ratings and context 
including required mitigation--we find the take from Western's survey 
activities will have a negligible impact on most remaining delphinid 
species (i.e., all stocks of bottlenose dolphin, two species of spotted 
dolphin, rough-toothed dolphin, striped dolphin, common dolphin, and 
Risso's dolphin).
    For those species with de minimis impact ratings we believe that, 
absent additional relevant concerns related to

[[Page 63374]]

population status or context, the rating implies that a negligible 
impact should be expected as a result of the specified activity. No 
such concerns exist for these species, and we find the take from 
Western's survey activities will have a negligible impact on the 
Clymene dolphin and harbor porpoise.
    In summary, based on the analysis contained herein of the likely 
effects of the specified activity on marine mammals and their habitat, 
and taking into consideration the implementation of the required 
monitoring and mitigation measures, we find that the total marine 
mammal take from Western's survey activities will have a negligible 
impact on all affected marine mammal species or stocks.
    CGG--CGG has planned an approximately 155-day survey program, or 42 
percent of the year (approximately two seasons). However, the planned 
survey would cover a large spatial extent (i.e., a majority of the mid- 
and south Atlantic; see Figure 3 of CGG's application). Therefore, 
although the survey would be long-term (i.e., greater than one season) 
in total duration, we would not expect the duration of effect to be 
greater than moderate and intermittent in any given area. Table 14 
displays relevant information leading to impact ratings for each 
species resulting from CGG's survey. In general, we note that although 
the temporal and spatial scale of the planned survey activity is large, 
the fact that this mobile acoustic source would be moving across large 
areas (as compared with geophysical surveys with different objectives 
that may require focused effort over long periods of time in smaller 
areas) means that more individuals may receive limited exposure to 
survey noise, versus fewer individuals receiving more intense exposure 
and/or for longer periods of time. The nature of such potentially 
transitory exposure means that the potential significance of behavioral 
disruption and potential for longer-term avoidance of important areas 
is limited.

                                                       Table 14--Magnitude and Impact Ratings, CGG
--------------------------------------------------------------------------------------------------------------------------------------------------------
              Species                        Amount              Spatial extent         Magnitude rating         Consequences        Impact rating \1\
--------------------------------------------------------------------------------------------------------------------------------------------------------
North Atlantic right whale.........  De minimis............  Low-Moderate..........  De minimis...........  Medium...............  Low.
Humpback whale.....................  De minimis............  Low-Moderate..........  De minimis...........  Medium...............  Low.
Minke whale........................  De minimis............  Low-High..............  De minimis...........  Medium...............  Low.
Fin whale..........................  De minimis............  Low...................  De minimis...........  Medium...............  Low.
Sperm whale........................  Low...................  Moderate..............  Medium...............  Medium...............  Moderate.
Kogia spp..........................  Low...................  High..................  High.................  Low..................  Moderate.
Beaked whales......................  Low...................  Moderate..............  Medium...............  High.................  Moderate.
Rough-toothed dolphin..............  Moderate..............  High..................  High.................  Low..................  Moderate.
Bottlenose dolphin.................  Low...................  High..................  High.................  Low..................  Moderate.
Clymene dolphin....................  High..................  High..................  High.................  Low..................  Moderate.
Atlantic spotted dolphin...........  Low...................  Moderate..............  Medium...............  Low..................  Low.
Pantropical spotted dolphin........  Moderate..............  High..................  High.................  Low..................  Moderate.
Striped dolphin....................  De minimis............  Low...................  De minimis...........  Low..................  De minimis.
Common dolphin.....................  De minimis............  Low-moderate..........  De minimis...........  Low..................  De minimis.
Risso's dolphin....................  De minimis............  Low-moderate..........  De minimis...........  Low..................  De minimis.
Pilot whales.......................  Low...................  Moderate..............  Medium...............  Medium...............  Moderate.
Harbor porpoise....................  De minimis............  Low...................  De minimis...........  Low..................  De minimis.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Impact rating does not indicate whether overall impact to the species or stock is negligible, but is considered with relevant contextual factors
  (described generally above and specifically below) in order to ultimately determine whether the effects of the specified activity on the affected
  species or stock are negligible.

    The North Atlantic right whale is endangered, has a very low 
population size, and faces significant additional stressors. Therefore, 
regardless of impact rating, we believe that the required mitigation 
described previously is critically important in order for us to make 
the necessary finding and it is with consideration of this mitigation 
that we find the take from CGG's survey activities will have a 
negligible impact on the North Atlantic right whale.
    Magnitude ratings for the sperm whale and beaked whales are medium; 
however, consequence factors are medium and high, respectively. 
Magnitude rating for pilot whales is medium but, similar to beaked 
whales, we expect that compensatory ability will be low (high 
consequence rating) due to presumed residency in areas targeted by the 
planned survey--leading to a moderate impact rating. However, 
regardless of impact rating, the consideration of likely consequences 
and contextual factors for all three taxa leads us to conclude that 
targeted mitigation is important to support a finding that the effects 
of the survey will have a negligible impact on these species. As 
described previously, sperm whales are an endangered species with 
particular susceptibility to disruption of foraging behavior, beaked 
whales are particularly acoustically sensitive (with presumed low 
compensatory ability), and pilot whales are sensitive to additional 
stressors due to a high degree of mortality in commercial fisheries 
(and also with low compensatory ability). Finally, due to their 
acoustic sensitivity, we require shutdown of the acoustic source upon 
detection of a beaked whale at extended distance from the source 
vessel. In consideration of the required mitigation, we find the take 
from CGG's survey activities will have a negligible impact on the sperm 
whale, beaked whales (i.e., Ziphius cavirostris and Mesoplodon spp.), 
and pilot whales (i.e., Globicephala spp.).
    Kogia spp. receive a moderate impact rating. However, although NMFS 
does not currently identify a trend for these populations, recent 
survey effort and stranding data show a simultaneous increase in at-sea 
abundance and strandings, suggesting growing Kogia spp. abundance 
(NMFS, 2011; 2013a; Waring et al., 2007; 2013). Finally, we expect that 
Kogia spp. will receive subsidiary benefit from the required mitigation 
targeted for sperm whales, beaked whales, and pilot whales and, 
although minimally effective due to the difficulty of at-sea 
observation of Kogia spp., we have required shutdown of the acoustic 
source upon observation of Kogia spp. at extended distance from the 
source vessel. In consideration of these factors--likely population 
increase and required mitigation--we find the take from CGG's survey 
activities will have a negligible impact on Kogia spp.

[[Page 63375]]

    As described in the introduction to this analysis, it is assumed 
that likely consequences are somewhat higher for species of mysticete 
whales (low-frequency hearing specialists) due to the greater potential 
for masking impacts at longer ranges than other taxa and at frequencies 
that overlap a larger portion of both their hearing and vocalization 
ranges. Therefore, despite de minimis magnitude ratings, we expect some 
consequences to individual humpback, fin, and minke whales, i.e., 
leading to a low impact rating. However, given the minimal amount of 
interaction expected between these species and the survey activities, 
and in consideration of the overall low impact ratings, we find the 
take from CGG's planned survey activities will have a negligible impact 
on the humpback whale, fin whale, and minke whale.
    Despite medium to high magnitude ratings (with some exceptions), 
most remaining delphinid species receive low to moderate impact ratings 
due to consequences relating to a lack of propensity for behavioral 
disruption due to airgun survey activity and our expectation that these 
species would generally have relatively high compensatory ability. In 
addition, contextually these species do not have significant issues 
relating to population status or context. Many oceanic delphinid 
species are generally more associated with dynamic oceanographic 
characteristics rather than static physical features, and those species 
(such as common dolphin) with substantial distribution to the north of 
the survey area would likely be little affected at the population level 
by the specified activity. For example, both species of spotted dolphin 
and the offshore stock of bottlenose dolphin range widely over slope 
and abyssal waters (e.g., Waring et al., 2014; Hayes et al., 2017; 
Roberts et al., 2016), while the rough-toothed dolphin does not appear 
bound by water depth in its range (Ritter, 2002; Wells et al., 2008). 
Our required mitigation largely eliminates potential effects to 
depleted coastal stocks of bottlenose dolphin. We also expect that 
meaningful subsidiary benefit will accrue to certain species from the 
mitigation targeted for sperm whales, beaked whales, and pilot whales, 
most notably to species presumed to have greater association with shelf 
break waters north of Cape Hatteras (e.g., offshore bottlenose 
dolphins). In consideration of these factors--overall impact ratings 
and context including required mitigation--we find the take from CGG's 
survey activities will have a negligible impact on remaining delphinid 
species (i.e., all stocks of bottlenose dolphin, two species of spotted 
dolphin, rough-toothed dolphin, and Clymene dolphin).
    For those species with de minimis impact ratings we believe that, 
absent additional relevant concerns related to population status or 
context, the rating implies that a negligible impact should be expected 
as a result of the specified activity. No such concerns exist for these 
species, and we find the take from CGG's survey activities will have a 
negligible impact on the common dolphin, striped dolphin, Risso's 
dolphin, and harbor porpoise.
    In summary, based on the analysis contained herein of the likely 
effects of the specified activity on marine mammals and their habitat, 
and taking into consideration the implementation of the required 
monitoring and mitigation measures, we find that the total marine 
mammal take from CGG's survey activities will have a negligible impact 
on all affected marine mammal species or stocks.

Small Numbers Analyses

    The MMPA does not define ``small numbers.'' NMFS's and the U.S. 
Fish and Wildlife Service's 1989 implementing regulations defined small 
numbers as a portion of a marine mammal species or stock whose taking 
would have a negligible impact on that species or stock. This 
definition was invalidated in Natural Resources Defense Council v. 
Evans, 279 F.Supp.2d 1129 (2003) (N.D. Cal. 2003), based on the court's 
determination that the regulatory definition of small numbers was 
improperly conflated with the regulatory definition of ``negligible 
impact,'' which rendered the small numbers standard superfluous. As the 
court observed, ``the plain language indicates that small numbers is a 
separate requirement from negligible impact.'' Since that time, NMFS 
has not applied the definition found in its regulations. Rather, 
consistent with Congress' pronouncement that small numbers is not a 
concept that can be expressed in absolute terms (House Committee on 
Merchant Marine and Fisheries Report No. 97-228 (September 16, 1981)), 
NMFS makes its small numbers findings based on an analysis of whether 
the number of individuals authorized to be taken annually from a 
specified activity is small relative to the stock or population size. 
The Ninth Circuit has upheld a similar approach. See Center for 
Biological Diversity v. Salazar, No. 10-35123, 2012 WL 3570667 (9th 
Cir. Aug. 21, 2012). However, we have not historically indicated what 
we believe the upper limit of small numbers is.
    To maintain an interpretation of small numbers as a proportion of a 
species or stock that does not conflate with negligible impact, we use 
the following framework. A plain reading of ``small'' implies as 
corollary that there also could be ``medium'' or ``large'' numbers of 
animals from the species or stock taken. We therefore use a simple 
approach that establishes equal bins corresponding to small, medium, 
and large proportions of the population abundance.
    NMFS's practice for making small numbers determinations is to 
compare the number of individuals estimated and authorized to be taken 
(often using estimates of total instances of take, without regard to 
whether individuals are exposed more than once) against the best 
available abundance estimate for that species or stock. We note, 
however, that although NMFS's implementing regulations require 
applications for incidental take to include an estimate of the marine 
mammals to be taken, there is nothing in paragraphs (A) or (D) of 
section 101(a)(5) that requires NMFS to quantify or estimate numbers of 
marine mammals to be taken for purposes of evaluating whether the 
number is small. (See CBD v. Salazar.) While it can be challenging to 
predict the numbers of individual marine mammals that will be taken by 
an activity (again, many models calculate instances of take and are 
unable to account for repeated exposures of individuals), in some cases 
we are able to generate a reasonable estimate utilizing a combination 
of quantitative tools and qualitative information. When it is possible 
to predict with relative confidence the number of individual marine 
mammals of each species or stock that are likely to be taken, the small 
numbers determination should be based directly upon whether or not 
these estimates exceed one third of the stock abundance. In other 
words, consistent with past practice, when the estimated number of 
individual animals taken (which may or may not be assumed as equal to 
the total number of takes, depending on the available information) is 
up to, but not greater than, one third of the species or stock 
abundance, NMFS will determine that the numbers of marine mammals taken 
of a species or stock are small.
    Another circumstance in which NMFS considers it appropriate to make 
a small numbers finding is in the case of a species or stock that may 
potentially be taken but is either rarely encountered or only expected 
to be taken on rare occasions. In that

[[Page 63376]]

circumstance, one or two assumed encounters with a group of animals 
(meaning a group that is traveling together or aggregated, and thus 
exposed to a stressor at the same approximate time) should reasonably 
be considered small numbers, regardless of consideration of the 
proportion of the stock (if known), as rare encounters resulting in 
take of one or two groups should be considered small relative to the 
range and distribution of any stock.
    In summary, when quantitative take estimates of individual marine 
mammals are available or inferable through consideration of additional 
factors, and the number of animals taken is one third or less of the 
best available abundance estimate for the species or stock, NMFS 
considers it to be of small numbers. NMFS may appropriately find that 
one or two predicted group encounters will result in small numbers of 
take relative to the range and distribution of a species, regardless of 
the estimated proportion of the abundance.
    Please see Table 15 for information relating to the basis for our 
small numbers analyses. For the sei whale, Bryde's whale, blue whale, 
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. Therefore, for each applicant, based on the 
analyses contained herein of their specified activity, we find that 
small numbers of marine mammals will be taken for each of these 11 
affected species or stocks for each specified activity. We do not 
discuss these 11 species further in the applicant-specific analyses 
that follow.

                               Table 15--Total Instances of Take Authorized 1 and Proportion of Best Abundance Estimate 2
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                Abundance       Spectrum \8\             TGS \3\                 ION                 Western                 CGG
         Common name             estimate  -------------------------------------------------------------------------------------------------------------
                                   \4\         Take        %         Take        %         Take        %         Take        %         Take        %
--------------------------------------------------------------------------------------------------------------------------------------------------------
North Atlantic right whale...          458          6          1          9          2          2         <1          4          1          2         <1
Humpback whale...............    \5\ 2,002         45          2         60          3          7         <1         49          2          7         <1
Minke whale..................       20,741        423          2        212          1         12         <1        100         <1        128          1
Fin whale....................    \5\ 6,582        337          5      1,144         17          5         <1        537          8         49          1
Sperm whale..................    \5\ 9,649      1,077         11      3,579         37         16         <1      1,941         20      1,304         14
Kogia spp....................        3,785        205          5      1,221         32         30          1        572         15        240          6
Beaked whales................   \6\ 25,284      3,357         13     12,072         48        490          2      4,960         20      3,511         14
Rough-toothed dolphin........      \7\ 845        201         24        261         31         14          2        123         15        177         21
Bottlenose dolphin...........  \5\ 149,785     37,562         25     40,595         27      2,599          2     23,600         16      9,063          6
Clymene dolphin..............   \7\ 24,018      6,459         27        821          3        252          1        391          2      6,382         27
Atlantic spotted dolphin.....  \6\ 107,100     16,926         16     41,222         38        568          1     18,724         17      6,596          6
Pantropical spotted dolphin..    \7\ 7,217      1,632         23      1,470         20         78          1        690         10      1,566         22
Striped dolphin..............  \6\ 158,258      8,022          5     23,418         15        162         <1      8,845          6      6,328          4
Common dolphin...............      173,486     11,087          6     52,728         30        372         <1     20,683         12      6,026          3
Risso's dolphin..............   \5\ 19,437        755          4      3,241         17         90         <1      1,608          8        809          4
Globicephala spp.............   \6\ 34,531      2,765          8      8,902         26        199          1      4,682         14      1,964          6
Harbor porpoise..............   \5\ 50,406        627          1        325          1         21         <1        155         <1         30         <1
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Total take authorized includes take by Level A and Level B harassment. Please see Table 6 for details.
\2\ Species for which take resulting from a single exposure of one group of each species or stock are not included in this table. Please see discussion
  preceding this table.
\3\ Additional analysis was conducted to specify the number of individuals taken for TGS. Please see discussion below and Table 16.
\4\ Best abundance estimate; please see discussion under ``Description of Marine Mammals in the Area of the Specified Activities.'' For most taxa, the
  best abundance estimate for purposes of comparison with take estimates is considered here to be the model-predicted abundance (Roberts et al., 2016).
  For these taxa, model-predicted abundances within the EEZ and estimates for the portion of the specific geographic region beyond the EEZ are combined
  to obtain the total abundance. For those taxa where a density surface model was produced, maximum monthly abundance was considered appropriate for
  some, and for others the maximum mean seasonal abundance was used as a precaution. For those taxa where only a stratified model was produced, only
  mean annual abundance is available. For several taxa, other abundance estimates were deemed most appropriate, as described previously in this notice.
\5\ Maximum monthly abundance.
\6\ Maximum seasonal abundance.
\7\ Mean annual abundance.
\8\ Small numbers analyses were completed prior to receipt of a modified survey plan from Spectrum and subsequent revision of authorized take numbers
  reflecting the modification. Here, we retain the original take estimates for Spectrum in context of the small numbers analysis described below. Please
  see ``Spectrum Survey Plan Modification,'' below, for additional information describing the modified survey plan, findings made in context of the
  analysis presented below, and authorized take for Spectrum (Table 17).

    As discussed previously, the MMPA does not define small numbers. 
NMFS compares the estimated numbers of individuals expected to be taken 
(when available; often take estimates are presented as estimated 
instances of take) to the most appropriate estimation of the relevant 
species or stock size in our determination of whether an authorization 
is limited to small numbers of marine mammals, i.e., less than one-
third of the most appropriate abundance estimate (Table 15). In the 
Notice of Proposed Authorization, we proposed to limit the 
authorization of take to approximately one-third of the most 
appropriate stock abundance estimate, assuming no other relevant 
factors that provide more context for the estimate (e.g., information 
that the take estimate numbers represent instances of multiple 
exposures of the same animals). Further, we proposed that, in order to 
limit actual take to this proportion of estimated stock abundance, we 
would require monthly reporting from those applicants with predicted 
exposures of any species exceeding this threshold. Those interim 
reports would include corrected numbers of marine mammals ``taken'' 
and, upon reaching the pre-determined take threshold, any issued IHA 
would be withdrawn.
    However, as discussed elsewhere in this notice (including in 
``Comments and Responses''), we received numerous comments criticizing 
this approach. Notably, comments indicated that the pre-determined 
threshold (described in our Notice of Proposed IHAs as30 percent) was 
arbitrary and not rooted in any meaningful biological consideration, 
and that the proposal--i.e., to limit the actual take authorization to 
less than what was estimated in terms of potential exposures, require a 
novel reporting scheme, and potentially withdraw IHAs if the threshold 
was crossed--was impracticable. However, in this Notice we have more 
fully described and clarified our approach to small numbers, and used 
this approach for

[[Page 63377]]

issuance of the IHAs. As a result of the concerns presented by 
applicants and commenters regarding the justification for and 
practicability of our proposal, we reconsidered the available 
information and re-evaluated and refined our small numbers analyses, as 
described next. With regard to use of the most appropriate population 
abundance (Table 15), please see additional discussion under 
``Description of Marine Mammals in the Area of the Specified 
Activities.''
    The number of exposures presented in Table 15 represent the 
estimated number of instantaneous instances in which an individual from 
each species or stock would be exposed to sound fields from airgun 
surveys at or above the 160 dB rms threshold. They do not necessarily 
represent the estimated number of individuals of each species that 
would be exposed, nor do they provide information on the duration of 
the exposure. In this case, the likelihood that any individual of a 
given species is exposed more than once is low due to the movement of 
both the vessels and the animals themselves. That said, for species 
where the estimated exposure numbers are higher compared to the 
population abundance, we assume that some individuals may be exposed 
more than once, meaning the exposures given in Table 15 overestimate 
the numbers of individuals that would be exposed. Applicant-specific 
analyses follow.
    Spectrum--The total amount of taking assessed for all affected 
stocks on the basis of Spectrum's original survey plan ranges from 1 to 
27 percent of the most appropriate population abundance estimate, and 
is therefore less than the appropriate small numbers threshold (i.e., 
one-third of the most appropriate population abundance estimate). These 
proportions are considered overestimates with regard to the small 
numbers findings, as they likely represent multiple exposures of some 
of the same individuals for some stocks. However, we do not have 
sufficient information on which to base an estimate of individuals 
taken versus instances of take. Please see ``Spectrum Survey Plan 
Modification,'' below, for additional information describing the 
modified survey plan, findings made in context of the analysis 
presented here, and authorized take for Spectrum (Table 17).
    Based on the analysis contained herein of Spectrum's specified 
activity, the required monitoring and mitigation measures, and the 
anticipated take of marine mammals, we find that small numbers of 
marine mammals will be taken relative to the population sizes of the 
affected species or stocks.
    TGS--The total amount of taking (in consideration of instances of 
take) authorized for a majority of affected stocks ranges from 1 to 32 
percent of the most appropriate population abundance estimate, and is 
therefore less than the appropriate small numbers threshold (i.e., one-
third of the most appropriate population abundance estimate). The total 
amount of taking (in consideration of instances of take) authorized for 
the sperm whale, beaked whales, and the Atlantic spotted dolphin is 
higher than the threshold. In this case, we have information available 
to distinguish between an estimate of individuals taken versus 
instances of take.
    TGS is the only applicant that provided an analysis of estimated 
individuals exposed versus instances of exposure (see Table 6-5 of 
TGS's application). As described in the introduction to this section, 
the number of individuals taken (versus total instances of take), is 
the relevant metric for comparison to population abundance in a small 
numbers analysis. We note, though, that total instances of take are 
routinely used to evaluate small numbers when data to distinguish 
individuals is not available, and we further note the conservativeness 
of the assumption, as the number of total instances of take equates to 
the highest possible number of individuals. For example, in some cases 
the total number of takes may exceed the number of individuals in a 
population abundance, meaning there are multiple exposures of at least 
some animals.
    We do not typically attempt to quantitatively assess this 
comparison of individuals taken versus instances of take when we do not 
have direct information regarding individuals exposed (e.g., we know 
that only a specific sub-population is potentially exposed or we know 
that uniquely identified individuals are exposed); therefore, we did 
not initially make use of the information provided by TGS in their 
application, instead proposing the take cap and reporting scheme 
described in the introduction to this section. As described above, 
commenters indicated that our proposed approach was flawed and, 
therefore, we further evaluated the available information.
    The conceptual approach to the analysis involves a comparison of 
total ensonified area to the portion of that total area that is 
ensonified more than once. For TGS, 84 percent of the total ensonified 
area is area that is ensonified more than once, i.e., ``overlap.'' In a 
static density model, the same animals occur in the overlap regardless 
of the time elapsed between the first and second exposure. If animals 
are static in space in the model, they are re-exposed in the model 
every time there is overlap. When overlap is counted toward the 
evaluation of small numbers (i.e., percent of the abundance that is 
``taken''), it effectively raises the total abundance possible in the 
model, creating a situation in which one could theoretically take more 
than the abundance to which one is comparing. This does not make sense 
from the perspective of comparing numbers of individuals taken to total 
abundance. Although portions of the overlap may be ensonified more than 
twice, we conservatively assume a maximum of one repeat ensonification.
    The number of individuals potentially taken (versus total incidents 
of take) can then be determined using the following equation: 
(Numerical Output of the Model)-(0.84 * Numerical Output of the Model) 
+ 0.5 * (0.84 * Numerical Output of the Model). This may be simplified 
as: 0.58 * Numerical Output of the Model. ``Numerical output of the 
model'' refers to the estimated total incidents of take. As we stated 
in the introduction to this section, where there are relatively few 
total takes, it is more likely that all takes occur to new individuals, 
though this is dependent on actual distribution and movement of animals 
in relation to the survey vessel. While there is no clear threshold as 
to what level of total takes indicates a likelihood of repeat taking of 
individuals, here we assume that total taking of a moderate or high 
magnitude (consistent with our approach to assessing magnitude in the 
negligible impact analysis framework; see ``Negligible Impact Analyses 
and Determinations''), i.e., greater than 15 percent, is required for 
repeat taking of individuals to be likely and applied this analysis 
only to those stocks.

                                             Table 16--Analysis of Individuals Taken Versus Total Takes, TGS
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                    Abundance                           Individuals             Individuals  Individuals
                           Common name                               estimate    Total take      %         taken         %       taken once  taken twice
--------------------------------------------------------------------------------------------------------------------------------------------------------
Fin whale........................................................        6,582        1,144         17          664         10          480          184

[[Page 63378]]

 
Sperm whale......................................................        9,649        3,579         37        2,076         22        1,503          573
Kogia spp........................................................        3,785        1,221         32          708         19          513          195
Beaked whales....................................................       25,284       12,072         48        7,002         28        5,070        1,932
Rough-toothed dolphin............................................          845          261         31          151         18          110           42
Bottlenose dolphin...............................................      149,785       40,595         27       23,545         16       17,050        6,495
Atlantic spotted dolphin.........................................      107,100       41,222         38       23,909         22       17,313        6,596
Pantropical spotted dolphin......................................        7,217        1,470         20          853         12          617          235
Common dolphin...................................................      173,486       52,728         30       30,582         18       22,146        8,436
Risso's dolphin..................................................       19,437        3,241         17        1,880         10        1,361          519
Globicephala spp.................................................       34,531        8,902         26        5,163         15        3,739        1,424
--------------------------------------------------------------------------------------------------------------------------------------------------------

    This approach also allows us to estimate the number of individuals 
that we assume to be taken once and the number assumed to be taken 
twice. As we noted previously, although it is possible that some 
individuals may be taken more than twice, we assume a maximum of one 
repeat ensonification (a conservative assumption in this small numbers 
analysis context). For example, if there are 1,144 total takes of fin 
whales, with 664 total individuals taken, and where:

a = number of animals with single take; b = number of animals with 
double take,
then: a + b = 664 and 2*a + b = 1,144 and, therefore, 2*a + 664-a = 
1,144. In this example for fin whales, we assume that 480 
individuals are taken twice and 184 individuals are taken once. 
(Note that values given in Table 16 for individuals taken once 
versus twice may not sum to the value given for total individuals 
taken due to rounding.)

    In summary, for those stocks for which we assume each authorized 
take represents a new individual, the total amount of taking authorized 
ranges from 1 to 15 percent of the most appropriate population 
abundance estimate (Table 15), and is therefore less than the 
appropriate small numbers threshold (i.e., one-third of the most 
appropriate population abundance estimate). For those stocks for which 
we assessed the number of expected individuals taken, the total amount 
of taking authorized ranges from 10 to 28 percent of the most 
appropriate population abundance estimate (Table 16), and is therefore 
less than the appropriate small numbers threshold (i.e., one-third of 
the most appropriate population abundance estimate). Based on the 
analysis contained herein of TGS's specified activity, the required 
monitoring and mitigation measures, and the anticipated take of marine 
mammals, we find that small numbers of marine mammals will be taken 
relative to the population sizes of the affected species or stocks.
    ION--The total amount of taking authorized for all affected stocks 
ranges from less than 1 to 4 percent of the most appropriate population 
abundance estimate, and is therefore less than the appropriate small 
numbers threshold (i.e., one-third of the most appropriate population 
abundance estimate).
    Based on the analysis contained herein of ION's specified activity, 
the required monitoring and mitigation measures, and the anticipated 
take of marine mammals, we find that small numbers of marine mammals 
will be taken relative to the population sizes of the affected species 
or stocks.
    Western--The total amount of taking authorized for all affected 
stocks ranges from less than 1 to 20 percent of the most appropriate 
population abundance estimate, and is therefore less than the 
appropriate small numbers threshold (i.e., one-third of the most 
appropriate population abundance estimate). These proportions are 
considered overestimates with regard to the small numbers findings, as 
they likely represent multiple exposures of some of the same 
individuals for some stocks. However, we do not have sufficient 
information on which to base an estimate of individuals taken versus 
instances of take.
    Based on the analysis contained herein of Western's specified 
activity, the required monitoring and mitigation measures, and the 
anticipated take of marine mammals, we find that small numbers of 
marine mammals will be taken relative to the population sizes of the 
affected species or stocks.
    CGG--The total amount of taking authorized for all affected stocks 
ranges from less than 1 to 27 percent of the most appropriate 
population abundance estimate, and is therefore less than the 
appropriate small numbers threshold (i.e., one-third of the most 
appropriate population abundance estimate). These proportions are 
considered overestimates with regard to the small numbers findings, as 
they likely represent multiple exposures of some of the same 
individuals for some stocks. However, we do not have sufficient 
information on which to base an estimate of individuals taken versus 
instances of take.
    Based on the analysis contained herein of CGG's specified activity, 
the required monitoring and mitigation measures, and the anticipated 
take of marine mammals, we find that small numbers of marine mammals 
will be taken relative to the population sizes of the affected species 
or stocks.

Impact on Availability of Affected Species for Taking for Subsistence 
Uses

    There are no relevant subsistence uses of marine mammals implicated 
by these actions. Therefore, relevant to the Spectrum, TGS, ION, CGG, 
and Western IHAs, we have determined that the total taking of affected 
species or stocks would not have an unmitigable adverse impact on the 
availability of such species or stocks for taking for subsistence 
purposes.

Spectrum Survey Plan Modification

    As described earlier in this notice, Spectrum's proposed survey 
plan described in our Notice of Proposed IHAs included ~21,635 km of 
survey line (see Figure 1 of Spectrum's application). However, on June 
4, 2018, Spectrum notified NMFS of a modification to their survey plan. 
NMFS's understanding is this modification is based on a voluntary 
collaborative effort between Spectrum and TGS, another IHA applicant, 
to reduce duplication of effort and expense. Subsequently, on June 26, 
2018, Spectrum submitted a final, revised modified survey plan. The 
modified survey plan occurs roughly within the same survey 
``footprint'' and consists of ~13,766 km of survey line (see Figure 
provided on p. 2 of Spectrum's letter notifying us of their intent to 
modify their survey plan). Therefore, the modified survey plan 
represents an approximate 36 percent decrease in total survey line. 
With this reduction in survey effort, Spectrum now estimates that the 
survey plan will require approximately 108 days of

[[Page 63379]]

operations (previously estimated as 165 days of operations).
    The changes to the survey plan, in summary, include the following: 
(1) Rotated the survey grid by approximately 5 degrees; (2) trimmed 
lines from most time-area restrictions; (3) removed certain lines; and 
(4) shifted certain lines. The figure provided on p. 3 of Spectrum's 
letter notifying us of their intent to modify their survey plan shows 
an overlay of the modified survey plan (red lines) with the previously 
proposed survey plan (black lines).
    Following receipt of the notification from Spectrum, we evaluated 
the potential effect of the change through use of a spatial analysis. 
In summary, we compared marine mammal densities within assumed 
ensonified areas associated with the original survey tracklines and 
associated with the modified survey tracklines. This allowed us to 
produce a ratio of the expected takes by Level B harassment from the 
modified survey to the original survey and, therefore, to evaluate the 
degree of change in terms of take. In conducting this evaluation, we 
used mean marine mammal densities over the 21 modeling areas or zones 
(extracted from Roberts et al. (2016)), as described previously in 
``Estimated Take.'' Detailed steps of the evaluation are as follows:
     Obtain trackline lengths for each relevant season and zone 
for proposed (i.e., the original) and modified Spectrum tracklines;
     Multiply trackline lengths by mean buffer widths for each 
zone to get area surveyed for both proposed and modified tracklines;
     Multiply these areas surveyed within each zone by each 
species density to get raw take by zone for proposed and modified 
tracklines for each species (accounting for implementation of North 
Atlantic right whale time-area restriction, in effect out to 90 km from 
shore from November through April);
     Create ratio of the expected take from the modified 
tracklines to the proposed tracklines; and
     Multiply this ratio by the originally proposed take 
numbers to obtain revised take numbers.
    However, note that we did not follow this process (i.e., developing 
a ratio for use in ``correcting'' the original take number) for North 
Atlantic right whales. Instead, we performed an identical analysis as 
that described previously in ``Description of Exposure Estimates--North 
Atlantic Right Whale,'' producing a new take estimate for this species 
(Table 17).
    The results of this evaluation in terms of take numbers are shown 
in Table 17. Our analysis of the potential for auditory injury of mid-
frequency cetaceans remains the same and, therefore, the amount of take 
by Level A harassment for these species is unchanged. For low-frequency 
cetaceans, the reduction in total survey line reduces the likely 
potential that take by Level A harassment would occur. The total amount 
of survey line in the modified survey plan is similar to that proposed 
by ION and, in fact, Spectrum's estimated auditory injury zone for low-
frequency cetaceans is slightly smaller than ION's. Therefore, we adopt 
the logic presented previously for ION in revising the authorized take 
by Level A harassment for low-frequency cetaceans (see ``Estimated 
Take'' for more detail). For high-frequency cetaceans, we revise the 
take authorized by Level A harassment according to the same procedure 
described previously in ``Estimated Take.'' For rarely occurring 
species (i.e., sei whale, Bryde's whale, blue whale, northern 
bottlenose whale, Fraser's dolphin, melon-headed whale, false killer 
whale, pygmy killer whale, killer whale, spinner dolphin, and white-
sided dolphin), we retain our take authorization of a single exposure 
of one group of each species or stock, as appropriate (using average 
group size). Therefore, our original analysis is retained for these 
species or stocks and we do not address them here.

                   Table 17--Take Estimates Associated With Proposed and Modified Tracklines and Proportion of Best Abundance Estimate
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                        Proposed tracklines                    Modified tracklines            Reduction
                                                              ------------------------------------------------------------------------------   in total
                         Common name                                                                                                          authorized
                                                                 Level A      Level B         %         Level A      Level B         %         take (%)
--------------------------------------------------------------------------------------------------------------------------------------------------------
North Atlantic right whale...................................            0            6            1            0            2           <1           67
Humpback whale...............................................            4           41            2            2           19            1           53
Minke whale..................................................            4          419            2            2          252            1           40
Fin whale....................................................            4          333            5            2          163            3           51
Sperm whale..................................................            0        1,077           11            0          684            7           36
Kogia spp....................................................            5          200            5            3          125            3           38
Beaked whales................................................            0        3,357           13            0        2,291            9           32
Rough-toothed dolphin........................................            0          201           24            0          117           14           42
Common bottlenose dolphin....................................            0       37,562           25            0       14,938           10           60
Clymene dolphin..............................................            0        6,459           27            0        4,045           17           37
Atlantic spotted dolphin.....................................            0       16,926           16            0        8,466            8           50
Pantropical spotted dolphin..................................            0        1,632           23            0        1,017           14           38
Striped dolphin..............................................            0        8,022            5            0        5,144            3           36
Common dolphin...............................................            0       11,087            6            0        6,008            3           46
Risso's dolphin..............................................            0          755            4            0          414            2           45
Pilot whales.................................................            0        2,765            8            0        1,591            5           42
Harbor porpoise..............................................           16          611            1            8          355            1           42
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Total authorized take for all species shown in Table 17 decreased. 
The modified survey plan largely remains within the footprint of the 
proposed survey plan, with the only notable change being the reduction 
of total survey line and the removal of survey line from certain areas 
within that footprint, including, importantly, the total removal of 
lines from within our designated seasonal ``Hatteras and North'' time-
area restriction along the shelf break off of Cape Hatteras (Area #4; 
Figure 4). This area constitutes some of the most important marine 
mammal

[[Page 63380]]

habitat within the specific geographical region.
    As previously described in ``Negligible Impact Analyses and 
Determinations,'' we have determined on the basis of Spectrum's 
proposed survey plan that the likely effects of the (previously 
described) specified activity on marine mammals and their habitat due 
to the total marine mammal take from Spectrum's survey activities would 
have a negligible impact on all affected marine mammal species or 
stocks. Based on our evaluation of Spectrum's modified survey plan, we 
affirm that this conclusion remains valid, and we authorize the revised 
take numbers shown in Table 17. Similarly, as previously described in 
``Small Numbers Analyses,'' we have determined that the take of marine 
mammals incidental to Spectrum's specified activity would represent 
small numbers of marine mammals relative to the population sizes of the 
affected species or stocks. All authorized take numbers for Spectrum 
have decreased from what we considered in that small numbers analysis 
and, therefore, we affirm that this conclusion remains valid.
    In conclusion, we affirm and restate our findings for Spectrum:
     All previously described mitigation, monitoring, and 
reporting requirements remain the same. Based on our evaluation of 
these measures, we have determined that the required mitigation 
measures provide the means of effecting the least practicable adverse 
impact on marine mammal species or stocks and their habitat, paying 
particular attention to rookeries, mating grounds, and areas of similar 
significance.
     With regard to the negligible impact analysis, we refer 
the reader to the analysis presented previously. In addition, our 
evaluation of the modified survey plan shows (1) total survey line is 
reduced by approximately one-third; (2) the modified survey plan does 
not include new areas not originally considered in our assessment of 
the effects of Spectrum's specified activity; (3) Spectrum has removed 
lines from portions of the survey area, including important habitat for 
marine mammals; and (4) authorized take for all taxa has been reduced. 
Therefore, based on the analysis contained herein of the likely effects 
of the specified activity on marine mammals and their habitat, and 
taking into consideration the implementation of the required monitoring 
and mitigation measures, we find that the total marine mammal take from 
Spectrum's survey activities will have a negligible impact on the 
affected marine mammal species or stocks.
     With regard to the small numbers analysis, we refer the 
reader to the analysis presented previously. Our evaluation of 
Spectrum's modified survey plan results in a reduction of authorized 
take for all taxa. Therefore, based on the analysis contained herein of 
Spectrum's specified activity, the required monitoring and mitigation 
measures, and the anticipated take of marine mammals, we find that 
small numbers of marine mammals will be taken relative to the 
population sizes of the affected species or stocks.

Endangered Species Act (ESA)

    Section 7 of the ESA requires Federal agencies to insure that their 
actions are not likely to jeopardize the continued existence of 
endangered or threatened species or adversely modify or destroy their 
designated critical habitat. Federal agencies must consult with NMFS 
for actions that may affect species under NMFS's jurisdiction listed as 
threatened or endangered or critical habitat designated for such 
species.
    At the conclusion of consultation, the consulting agency provides 
an opinion stating whether the Federal agency's action is likely to 
jeopardize the continued existence of ESA-listed species or destroy or 
adversely modify designated critical habitat.
    NMFS's issuance of IHAs to the five companies is subject to the 
requirements of Section 7 of the ESA. Therefore, NMFS's Office of 
Protected Resources (OPR), Permits and Conservation Division requested 
initiation of a formal consultation with the NMFS OPR, ESA Interagency 
Cooperation Division on the proposed issuance of IHAs on June 5, 2017. 
The formal consultation concluded in November 2018 and a final 
Biological Opinion (BiOp) was issued. The BiOp found that the Permits 
and Conservation Division's proposed action of issuing the five IHAs is 
not likely to jeopardize the continued existence or recovery of blue 
whales, fin whales, North Atlantic right whales, sei whales, or sperm 
whales. Furthermore, the BiOp found that the proposed action is also 
not likely to adversely affect designated critical habitat for North 
Atlantic right whales.

National Environmental Policy Act

    In 2014, the BOEM produced a final Programmatic Environmental 
Impact Statement (PEIS) to evaluate the direct, indirect, and 
cumulative impacts of geological and geophysical survey activities on 
the Mid- and South Atlantic OCS, pursuant to requirements of NEPA. 
These activities include geophysical surveys in support of hydrocarbon 
exploration, as were proposed in the MMPA applications before NMFS. The 
PEIS is available at: www.boem.gov/Atlantic-G-G-PEIS/. NOAA, through 
NMFS, participated in preparation of the PEIS as a cooperating agency 
due to its legal jurisdiction and special expertise in conservation and 
management of marine mammals, including its responsibility to authorize 
incidental take of marine mammals under the MMPA.
    NEPA, Council on Environmental Quality (CEQ) regulations, and 
NOAA's NEPA implementing procedures (NOAA Administrative Order (NAO) 
216-6A) encourage the use of programmatic NEPA documents and tiering to 
streamline decision-making in staged decision-making processes that 
progress from programmatic analyses to site-specific reviews. NMFS 
reviewed the Final PEIS and determined that it meets the requirements 
of the CEQ regulations (40 CFR part 1500-1508) and NAO 216-6A. NMFS 
further determined, after independent review, that the Final PEIS 
satisfied NMFS's comments and suggestions in the NEPA process. In our 
Notice of Proposed IHAs, we stated our intention to adopt BOEM's 
analysis in order to assess the impacts to the human environment of 
issuance of the subject IHAs, and that we would review all comments 
submitted in response to the notice as we completed the NEPA process, 
including a final decision of whether to adopt BOEM's PEIS and sign a 
Record of Decision related to issuance of IHAs. Following review of 
public comments received, we confirmed that it would be appropriate to 
adopt BOEM's analysis in order to support our assessment of the impacts 
to the human environment of issuance of the subject IHAs. Therefore, on 
February 23, 2018, NMFS signed a Record of Decision for the following 
purposes: (1) To adopt the Final PEIS to support NMFS's analysis 
associated with issuance of incidental take authorizations pursuant to 
sections 101(a)(5)(A) or (D) of the MMPA and the regulations governing 
the taking and importing of marine mammals (50 CFR part 216), and (2) 
in accordance with 40 CFR 1505.2, to announce and explain the basis for 
our decision to review and potentially issue incidental take 
authorizations under the MMPA on a case-by-case basis, if appropriate.
    Following review of public comment, we also determined that 
conducting additional NEPA review and preparing a tiered Environmental 
Assessment (EA) is appropriate to analyze environmental impacts 
associated with NMFS's issuance of separate IHAs to five different 
applicants. Through the description and analysis of NMFS's

[[Page 63381]]

activity provided in the EA as well as the analyses incorporated by 
reference from the Notice of Proposed IHAs and BOEM's PEIS, NMFS found 
that authorizing take of marine mammals by issuing individual IHAs to 
the five applicants will not result in significant direct, indirect, or 
cumulative impacts to the human environment. Accordingly, NMFS 
determined that issuance of IHAs to the five applicants would not 
significantly impact the quality of the human environment and signed a 
Finding of No Significant Impact (FONSI). NMFS's ROD, EA, and FONSI are 
available online at: www.fisheries.noaa.gov/action/incidental-take-authorization-oil-and-gas-industry-geophysical-survey-activity-atlantic.

Authorizations

    As a result of these determinations, NMFS has issued five separate 
IHAs to the aforementioned applicant companies for conducting the 
described geophysical survey activities in the Atlantic Ocean within 
the specific geographic region, incorporating the previously mentioned 
mitigation, monitoring, and reporting requirements.

    Dated: November 30, 2018.
Donna S. Wieting,
Director, Office of Protected Resources, National Marine Fisheries 
Service.
[FR Doc. 2018-26460 Filed 12-6-18; 8:45 am]
BILLING CODE 3510-22-P