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

> Briefs, arguments, decisions, and more.

URL: https://www.frixlaw.com/law-library/documents/fr%3A2017-11542

## Record

- **Collection:** Federal Register
- **Document type:** Notice
- **Published:** June 6, 2017
- **Citation:** 82 FR 26244

## Text

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; five proposed incidental harassment authorizations; request for comments.

SUMMARY:

NMFS has received five requests for authorization to take marine mammals incidental to conducting geophysical survey activity in the Atlantic Ocean. Pursuant to the Marine Mammal Protection Act (MMPA), NMFS is requesting comments on its proposal to issue incidental harassment authorizations (IHA) to incidentally take marine mammals during the specified activities.

DATES:

Comments and information must be received no later than July 6, 2017.

ADDRESSES:

Comments should be addressed to Jolie Harrison, Chief, Permits and Conservation Division, Office of Protected Resources, National Marine Fisheries Service. Physical comments should be sent to 1315 East-West Highway, Silver Spring, MD 20910 and electronic comments should be sent to
ITP.Laws@noaa.gov.

Instructions:
NMFS is not responsible for comments sent by any other method, to any other address or individual, or received after the end of the comment period. Comments received electronically, including all attachments, must not exceed a 25-megabyte file size. Attachments to electronic comments will be accepted in Microsoft Word or Excel or Adobe PDF file formats only. All comments received are a part of the public record and will generally be posted online at
www.nmfs.noaa.gov/pr/permits/incidental/oilgas.htm
without change. All personal identifying information (
e.g.,
name, address) voluntarily submitted by the commenter may be publicly accessible. Do not submit confidential business information or otherwise sensitive or protected information.

Information Solicited:
NMFS is seeking public input on these requests for authorization as outlined below and request that interested persons submit information, suggestions, and comments concerning the applications. We will only consider comments that are relevant to marine mammal species that occur in U.S. waters of the Mid- and South Atlantic and the potential effects of geophysical survey activities on those species and their habitat.

Comments indicating general support for or opposition to hydrocarbon exploration or any comments relating to hydrocarbon development (
e.g.,
leasing, drilling) are not relevant to this request for comments and will not be considered. Comments should indicate whether they are general to the proposed authorizations described herein or are specific to one or more of the five proposed authorizations, and should be supported by data or literature citations as appropriate.

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.nmfs.noaa.gov/pr/permits/incidental/oilgas.htm.
In case of problems accessing these documents, please call the contact listed above.

National Environmental Policy Act

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). These activities include geophysical surveys in support of hydrocarbon exploration, as are proposed in the MMPA applications before NMFS. The PEIS is available online at:
www.boem.gov/Atlantic-G-G-PEIS/.
NMFS participated in development of the PEIS as a cooperating agency and believes it appropriate to adopt the analysis in order to assess the impacts to the human environment of issuance of the subject IHAs. Information in the IHA applications, BOEM's PEIS, and this notice collectively provide the environmental information related to proposed issuance of these IHAs for public review and comment.

We will review all comments submitted in response to this notice as we complete 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, prior to a final decision on the incidental take authorization requests.

Background

Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361
et seq.
) direct the Secretary of Commerce to allow, upon request, the incidental, but not intentional, taking of small numbers of marine mammals by U.S. citizens who engage in a specified activity (other than commercial fishing) within a specified geographical region if certain findings are made and either regulations are issued or, if the taking is limited to harassment, a notice of a proposed authorization is provided to the public for review.

An authorization for incidental takings shall be granted if NMFS finds that the taking will have a negligible impact on the species or stock(s), will not have an unmitigable adverse impact on the availability of the species or stock(s) for subsistence uses (where relevant), and if the permissible methods of taking and requirements pertaining to the mitigation, monitoring and reporting of such takings are set forth. NMFS has defined “negligible impact” in 50 CFR 216.103 as “an impact resulting from the specified activity that cannot be reasonably expected to, and is not reasonably likely to, adversely affect the species or stock through effects on annual rates of recruitment or survival.”

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 2014-15, we received five 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.

On August 18, 2014, we received an application from Spectrum Geo Inc. (Spectrum), followed by revised versions on November 25, 2014, May 14, 2015, and July 6, 2015. TGS-NOPEC Geophysical Company (TGS) submitted an application on August 25, 2014, followed by revised versions on November 17, 2014, and July 21, 2015. We also received a request from ION GeoVentures (ION) on September 5, 2014, followed by a revised version on June 24, 2015.

We subsequently posted these applications for public review and sought public input (80 FR 45195; July 29, 2015), stating that we would only consider comments relevant to marine mammal species that occur in U.S. waters of the Mid- and South Atlantic and the potential effects of geophysical survey activities on those species. We stated further that any comments should be supported by data or literature citations as appropriate, that comments indicating general support for or opposition to oil and gas exploration and development would not be considered inasmuch as such comments are not relevant to our consideration of the requests under the MMPA, and that we were particularly interested in information addressing the following topics:

1. Best available scientific information and appropriate use of such information in assessing potential effects of the specified activities on marine mammals and their habitat;

2. Application approaches to estimating acoustic exposure and take of marine mammals; and,

3. Appropriate mitigation measures and monitoring requirements for these activities.

We note that this notice for proposed IHAs does not concern one additional company (TDI-Brooks International, Inc. (TDI Brooks)) whose application was referenced in our July 29, 2015,
Federal Register
notice, and includes two other companies (WesternGeco, LLC (Western) and CGG) whose applications were not included in our July 29, 2015, notice. TDI-Brooks International, Inc. submitted a request for authorization related to a proposed survey to conduct deep water multibeam bathymetry and sub-bottom profiler data acquisition on October 22, 2014. However, public comment indicated that this application was improperly considered adequate and complete, and we subsequently concurred with this assessment and returned the application to TDI-Brooks for revision. We will provide separate notice of any proposed authorization related to this applicant upon receipt of an adequate and complete application, if appropriate.

The comments and information received during this public review period informed development of the proposed IHAs discussed in this notice, and all letters received are available online at
www.nmfs.noaa.gov/pr/permits/incidental/oilgas.htm.

Following the close of the public review period, we received revised versions of several applications: From Spectrum on September 18, 2015, and from TGS on February 10, 2016. We received additional information from ION on February 29, 2016. Spectrum revised the scope of their proposed survey effort, while TGS and ION revised their estimates of the number of potential incidents of marine mammal exposure to underwater noise. Western submitted a request for authorization on March 3, 2015, followed by a revised version on February 17, 2016, that we determined was adequate and complete. CGG submitted a request for authorization on December 21, 2015, followed by revised versions on February 18, 2016, April 6, 2016, and May 26, 2016. These applications are adequate and complete at this time and are substantially similar to other applications previously released for public review. We do not anticipate offering additional discretionary public review of applications should we receive further requests for authorization related to proposed geophysical survey activity in the Atlantic Ocean.

All requested authorizations would be valid for the statutory maximum of one year from the date of effectiveness. All applicants propose to conduct two-dimensional (2D) marine seismic surveys using airgun arrays. Generally speaking, these surveys may occur within the U.S. Exclusive Economic Zone (
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 (Figure 1). Please see the applications for specific details of survey design. The use of airgun arrays is expected to 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 proposed surveys are described below.

Because the specified activity, specified geographic region, and proposed dates of activity are substantially similar for the five separate requests for authorization, we have determined it appropriate to provide a joint notice for the five proposed authorizations. However, while we provide relevant information together, we consider the potential impacts of the specified activities independently and make preliminary 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 propose 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 proposed surveys would be 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. 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 are silent 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). 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 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 (
e.g.,
10 km). Spacing and length of tracks varies by survey. Survey operations often involve the source vessel, supported by a chase vessel. Chase vessels typically support the source vessel by protecting the long 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 companies requested IHAs covering the statutory maximum of one year from the date of issuance, but 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 plans a six-month data acquisition program, consisting of an expected 165 days of seismic operations. TGS plans a full year data acquisition program, with an estimated 308 days of seismic operations. ION plans a six-month data acquisition program, 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-December), with an estimated 155 days of seismic operations. Seismic operations would typically occur 24 hours per day.

Specific Geographic Region

The proposed survey activities would occur off the Atlantic coast of the U.S., 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 U.S., the region between the U.S. exclusive economic zone (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). A map of all proposed surveys may be viewed online at:
www.boem.gov/Atlantic-G-and-G-Permitting/
(accessed on October 18, 2016); however, note that this map displays all permits requested from BOEM, including potential surveys for companies who have not yet requested authorization under the MMPA. The survey shown as “GXTechnology” on the referenced map is the same as what we describe here as being proposed by ION. In addition to general knowledge and other citations contained herein, this section relies upon the descriptions found in Sherman and Hempel (2009) and Wilkinson
et al.
(2009). As referred to here, productivity refers to fixated carbon (
i.e.,
g C/m
2
/yr) which relates to the carrying capacity of an ecosystem.

BILLING CODE 3510-22-P

EN06JN17.000

BILLING CODE 3510-22-C

The entire U.S. Atlantic coast region extends from the Gulf of Maine past Cape Hatteras to Florida. The region is characterized by its temperate climate and proximity to the Gulf Stream Current, and is generally considered to be of moderately high productivity, although the portion of the region from Cape Cod to Cape Hatteras is one of the most productive areas in the world due to upwellings along the shelf break created by the western edge of the Gulf Stream. Sea surface temperatures (SST) exhibit a broad range across this region, with winter temperatures ranging from 2-20 °C in the north and 15-22 °C in the south, while summer temperatures, consistent in the south at approximately 28 °C, range from 15-27 °C in the northern portion.

The northern portion of this region (
i.e.,
north of Cape Hatteras) is more complex, with four major sub-areas, only one of which is within the specified geographic region: The Mid-Atlantic Bight (MAB). South of Cape Cod, there is strong stratification along the coast where large estuaries occur (
e.g.,
Chesapeake Bay, Pamlico Sound). The Gulf Stream is highly influential on both the northern and southern portions of the region, but in different ways. Meanders of the current directly affect the southern portion of the region, where the Gulf Stream is closer to shore, while warm-core rings indirectly affect the northern portion (Belkin
et al.,
2009). In addition, subarctic influences can reach as far south as the MAB, but the convergence of the Gulf Stream with the coast near Cape Hatteras does not allow for significant northern influence into waters of the South Atlantic Bight.

The MAB includes the continental shelf and slope waters from Georges Bank to Cape Hatteras, NC. The retreat of the last ice sheet shaped the morphology and sediments of this area. The continental shelf south of New England is broad and flat, dominated by fine grained sediments (sand and silt). The shelf slopes gently away from the shore out to approximately 100 to 200 km offshore, where it transforms into the continental slope at the shelf break (at water depths of 100 to 200 m). Along the shelf break, numerous deep-water canyons incise the slope and shelf. The sediments and topography of the canyons are much more heterogeneous than the predominantly sandy top of the shelf, with steep walls and outcroppings of bedrock and deposits of clay.

The southwestern flow of cold shelf water feeding out of the Gulf of Maine and off Georges Bank dominates the circulatory patterns in this area. The countervailing Gulf Stream provides a source of warmer water along the coast as warm-core rings and meanders break off from the Gulf Stream and move shoreward, mixing with the colder shelf and slope water. As the shelf plain narrows to the south (the extent of the continental shelf is narrowest at Cape Hatteras), the warmer Gulf Stream waters run closer to shore.

The southeast continental shelf area extends approximately 1,500 km from Cape Hatteras, NC south to the Straits of Florida (Yoder, 1991). The continental shelf in the region reaches up to approximately 200 km offshore. The Gulf Stream influences the region with minor upwelling occurring along the Gulf Stream front. The area is approximately 300,000 km
2
, includes several protected areas and coral reefs (Aquarone, 2008); numerous estuaries and bays, nearshore and barrier islands; and extensive coastal marshes that provide habitats for numerous marine and estuarine species. A 10-20 km wide coastal zone is characterized by high levels of primary production throughout the year, while offshore, on the middle and outer shelf, upwelling along the Gulf Stream front and intrusions from the Gulf Stream cause seasonal phytoplankton blooms. Because of its high productivity, this sub-region supports active commercial and recreational fisheries (Shertzer
et al.,
2009).

Detailed Description of Activities

Detailed survey descriptions, as given in specific applications, are provided here without regard for the mitigation measures proposed by NMFS. In some cases, our proposed mitigation measures may affect the proposed survey plan (
e.g.,
distance from coast, areas to be avoided at certain times of year). Please see “Proposed Mitigation,” later in this document, for details on those proposed mitigation requirements. Please see Table 1 for a summary of airgun array characteristics.

ION
—ION proposes to conduct a 2D marine seismic survey off the U.S. east coast from Delaware to northern Florida (~38.5° N. to ~27.9° N.), and from 20 km from the coast to >600 km from the coast (see Figure 1 of ION's application). The survey would involve one source vessel, the M/V
Discoverer,
and one chase vessel, the M/V
Octopus,
or similar (see ION's application for vessel details). The
Discoverer
has a cruising speed of 9.5 knots (kn), maximum speed of 10 kn, and would tow gear during data acquisition at ~4 kn. The survey plan consists of five widely-spaced transect lines (~20-190 km apart) roughly parallel to the coast and 14 widely-spaced transect lines (~30-220 km apart) in the onshore-offshore direction totaling ~13,062 km of data acquisition line. Effort planned by depth bin is as follows: ~48 percent >3,000 m; ~18 percent 1,000-3,000 m; ~22 percent 100-1,000 m; ~12 percent <100 m. There would 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 could be some small amount of use of the acoustic source not accounted for in the total estimated line-km; however, this activity is difficult to quantify in advance and would represent an insignificant increase in effort.

The acoustic source planned for deployment is a 36-airgun array with a total volume of 6,420 in
3
. The source vessel would tow a single hydrophone streamer, up to 12 km long. The 36-airgun array would consist of a mixture of Bolt 1500LL and sleeve airguns ranging in volume from 40 in
3
to 380 in
3
; the larger (300-380 in
3
) airguns would be Bolt airguns, and the smaller (40-150 in
3
) airguns would be sleeve airguns. The difference between the two types of airguns is in the mechanical parts that release the pressurized air; however, the bubble and acoustic energy released by the two types of airguns are effectively the same. The airguns would be configured as four identical linear arrays or “strings” (see Figure 3 of ION's application). Each string would have nine airguns; the first and last airguns in the strings would be spaced ~15.5 m apart.

The four airgun strings would be distributed across an approximate area of 34 x 15.5 m behind the vessel and would be towed ~50-100 m behind the vessel at 10-m depth. The firing pressure of the array would be 2,000 pounds per square inch (psi). The airgun array would fire every 50 m or 20-24 s, depending on exact vessel speed—a longer interval than is typical of most industry seismic surveys. 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 proposed survey area. For more detail, please see “Estimated Take by Incidental Harassment,” later in this document, as well as Figures 4-6 and Appendix A of ION's application.

Spectrum
—Spectrum proposes to conduct a 2D marine seismic survey off the U.S. east coast from Delaware to northern Florida, extending throughout BOEM's Mid- and South Atlantic OCS planning areas. The survey would be conducted on an approximately 25 x 32 km grid; grid size may vary to minimize overall survey distance (see Figure 1 of Spectrum's application). The closest trackline to shore would be approximately 35 km (off Cape Hatteras). The survey would involve one source vessel and one chase vessel (see Spectrum's application for vessel details). The survey plan includes a total of approximately 21,635 km of data acquisition line, including allowance for lines expected to be resurveyed due to environmental or technical reasons. Water depths range from 30 to 5,410 m. There would be limited additional operations associated with equipment testing, startup, and repeat coverage of any areas where initial data quality is sub-standard.

The acoustic source planned for deployment is a 32-airgun array with a total volume of 4,920 in
3
. The source vessel would tow a single 12-km hydrophone streamer. The 32-airgun array would consist of individual airguns ranging in volume from 50 in
3
to 250 in
3
. The firing pressure of the array would be 2,000 psi. The airguns would be configured as four subarrays (see Figure 2 in Appendix A of Spectrum's application). Each string would have eight to ten airguns and strings would be spaced 10 m apart; the total array dimensions would be 40 m wide x 30 m long.

The four airgun strings would be towed at 6 to 10-m depth and the airgun array would fire every 25 m or 10 s, depending on exact vessel speed (expected to be 4-5 kn). 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 proposed survey area. For more detail, please see Appendix A of Spectrum's application, as well as “Estimated Take by Incidental Harassment,” later in this document.

TGS
—TGS proposes to conduct a 2D marine seismic survey off the U.S. east coast from Delaware to northern Florida, extending throughout BOEM's Mid- and South Atlantic OCS planning areas (see Figure 1-1 of TGS's application). The survey would involve two source vessels operating independently of one another (expected to operate at least 100 km apart), with each attended by one chase vessel. This approach was selected to allow TGS to complete the survey plan within one year rather than spread over multiple years. The survey plan consists of two contiguous survey grids with differently spaced lines (see Figures 1-1 to 1-4 of TGS's application). Lines are spaced 100 km apart in approximately the eastern half of the project area and approximately 25 km apart in the western portion of the survey area. A third, more detailed grid (6-10 km spacing) covers the continental shelf drop-off, approximately near the center of the proposed survey area from north to south. The closest trackline to the coast would be 25 km. The survey plan includes a total of 55,133 km of data acquisition line plus an additional 3,167 km of trackline expected for run-in/run-out, for a total of 58,300 km. Water depths range from 25-5,500 m. There would be limited additional operations associated with equipment testing, startup, line changes, and repeat coverage of any areas where initial data quality is sub-standard.

The acoustic sources planned for deployment are 48-airgun arrays with a total volume of 4,808 in
3
. However, only 40 individual airguns would be used at any given time, with remaining airguns held in reserve in case of equipment failure. The source vessels would tow a single 12-km long hydrophone streamer. The airgun array would use Sodera G-gun II airguns ranging in volume from 22 in
3
to 250 in
3
. The airguns would be configured as four identical subarrays (see Figure 3 in Appendix B of TGS's application), with individual elements spaced 8 m apart and arranged such that the largest elements are in the middle of each subarray and smaller sources at the front and end. The four airgun strings would be towed behind the vessel at 7-m depth. The airgun array would fire every 25 m (approximately every 10 s, depending on vessel speed), with expected transit speed of 4-5 kn. More detail regarding TGS's acoustic source and modeling related to TGS's application is provided in “Estimated Take by Incidental Harassment,” later in this document, as well as Appendix B of TGS's application.

Western
—Western proposes to conduct a 2D marine seismic survey off the U.S. east coast from Maryland to northern Florida, extending through the majority of BOEM's Mid- and South Atlantic OCS planning areas (see Figure 1-1 of Western's application). The survey plan consists of a survey grid with differently spaced lines (see Figures 1-1 to 1-4 of Western's application). Lines are spaced 25 km apart in approximately the southwestern third of the project area and approximately 6 km apart in the remainder of the survey area. The closest trackline to the coast would be 30 km. The survey plan includes a total of 26,641 km of data acquisition line plus an additional 689 km of lines expected for run-in/run-out, for a total of 27,330 km. Water depths range from 20-4,700 m. The survey would involve one source vessel, the M/V
Western Pride,
as well as two chase vessels, the M/V
Michael Lawrence
and M/V
Amber G,
and a supply vessel, the M/V
Melinda B. Adams
or similar (see Appendix B of Western's application for vessel details). There would be limited additional operations associated with equipment testing, startup, and repeat coverage of any areas where initial data quality is sub-standard.

The seismic source planned for deployment is a 24-airgun array with a total volume of 5,085 in
3
. The source vessel would tow a single 10.5-km hydrophone streamer. The 24-airgun array would consist of individual Bolt v5085 airguns. The airguns would be configured as three identical subarrays of eight airguns each with 8 m spacing between strings. The three airgun strings would be towed at 10-m depth and the airgun array would fire every 37.5 m (approximately every 16 s, depending on vessel speed), with expected transit speed of 4-5 kn. More detail regarding Western's acoustic source and modeling related to Western's application is provided in “Estimated Take by Incidental Harassment,” later in this document, as well as Appendix B of Western's application.

CGG
—CGG proposes to conduct a 2D marine seismic survey off the U.S. east coast from Virginia to Georgia, extending through the majority of BOEM's Mid- and South Atlantic OCS planning areas (see Figure 3 of CGG's application). The survey plan consists of 53 survey tracklines in a 20 km by 20 km orthogonal grid (see Figure 3 of CGG's application). The tracklines would be 300 to 750 km in length, with the closest trackline to the coast at 80 km. The survey plan includes a total of 28,670 km of data acquisition line, in water depths ranging from 100-5,000 m. The survey would involve one source vessel, as well as two support vessels. There would be limited additional operations associated with equipment testing, startup, and repeat coverage of any areas where initial data quality is sub-standard.

The seismic source planned for deployment is a 36-airgun array with a total volume of 5,400 in.
3
The source vessel would tow a single 10 to 12-km hydrophone streamer. The 36-airgun array would consist of individual Bolt 1900/1500 airguns. The airguns would be configured as four subarrays of nine airguns each (see Figure 2 in CGG's application), with total dimensions of 24 m width by 16.5 m length and 8 m separation between strings. The four airgun strings would be towed at 7-m depth and the airgun array would fire every 25 m (approximately every 16 s, depending on vessel speed), with expected transit speed of 4.5 kn. More detail regarding CGG's acoustic source and modeling related to CGG's application is provided in “Estimated Take by Incidental Harassment,” later in this document, as well as CGG's application.

Table 1—Survey and Airgun Array Characteristics

Company

Total
planned
survey
(km)

Total
volume

(in
3
)

Number of
guns

Number of
strings

Nominal source output

(downward)
1

0-pk
pk-pk
rms

Shot
interval
(m)

Tow
depth
(m)

ION
13,062
6,420
36
4
257
263

4
247

50
10

Spectrum
21,635
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

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).

Proposed Mitigation

In order to issue an IHA under Section 101(a)(5)(D) of the MMPA, NMFS must set forth the permissible methods of taking pursuant to such activity, “and other means of effecting the least practicable impact on such species or stock and its habitat, paying particular attention to rookeries, mating grounds, and areas of similar significance, and on the availability of such species or stock for taking” for certain subsistence uses. NMFS regulations require applicants for incidental take authorizations to include information about the availability and feasibility (economic and technological) of equipment, methods, and manner of conducting such activity or other means of effecting the least practicable adverse impact upon the affected species or stocks and their habitat (50 CFR 216.104(a)(11)). Here we provide a single description of proposed mitigation measures, including those contained in the applicants' requests, as we propose to require the same measures of all applicants.

We reviewed the applicants' proposals, the requirements specified in BOEM's PEIS, seismic mitigation protocols required or recommended elsewhere (
e.g.,
DOC, 2013; IBAMA, 2005; Kyhn
et al.,
2011; JNCC, 2010; DEWHA, 2008; BOEM, 2016a; DFO, 2008; MMOA, 2015; 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, 2015). The suite of mitigation measures proposed here 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. In carrying out the MMPA's mandate, we apply a 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 framework for such an evaluation is explained further in 82 FR 19460, 19502 (April 27, 2017) (Proposed Rule for Take of Marine Mammals Incidental to U.S. Navy Operation of Surveillance Towed Array Sensor System Low Frequency Active (SURTASS LFA) Sonar.) Both of these facets point to the need for a basic system of seismic mitigation protocols (which may be augmented as necessary) that may be implemented in the field, reduce subjective decision-making for observers to the extent possible, and appropriately weighs a range of potential outcomes from sound exposure in determining what should be avoided or minimized where possible.

Past mitigation protocols for geophysical survey activities using airgun arrays have focused on avoidance of exposures to received sound levels exceeding NMFS's historical injury criteria (
e.g.,
180 dB rms), rather than also weighing the potentially detrimental effects of increased input of sound at lower levels into the environment (
e.g.,
through use of mitigation guns or extended periods on the water to reshoot lines following shutdowns of the acoustic source), while also unrealistically assuming that shutdown protocols are capable of avoiding all potential for auditory injury. In addition to a basic suite of seismic mitigation protocols, we also include measures that might not be required for other activities (
e.g.,
time-area closures specific to the proposed surveys discussed here) but that are warranted here given the proposed spatiotemporal scope of these specified activities and associated potential for population-level effects and/or take of large numbers of individuals of certain species.

Mitigation-Related Monitoring

Monitoring by independent, dedicated, trained marine mammal observers is required. Note that, although we propose requirements related only to observation of marine mammals, we hereafter use the generic term “protected species observer” (PSO) to avoid confusion with protocols that may be required of the applicants pursuant to other relevant statutes. 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 seismic 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 “Proposed 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 elapsed since the conclusion of the at-sea experience. Both visual and acoustic monitoring is required; training and experience is specific to either visual or acoustic PSO duties. An experienced visual PSO must have completed approved, relevant training and 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 gained the requisite experience working as an acoustic PSO (
i.e.,
PAM operator).

NMFS does not currently approve specific training courses; observers may be considered appropriately trained by having satisfactorily completed training that meets all the requirements specified

herein (see “Proposed Monitoring and Reporting”). In order for PSOs to be approved, NMFS must review and approve PSO resumes accompanied by a relevant training course information packet that includes 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 successful completion of the course. 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; (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 “Proposed Monitoring and Reporting” section, later in this document.

Visual
—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. While it is desirable for all PSOs to be qualified through experience, we do not wish to foreclose opportunity for newly trained PSOs to gain the requisite 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. 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.

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. PSOs shall coordinate to ensure 360° 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. 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.

Visual monitoring must begin not less than 30 minutes prior to ramp-up 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.

During good conditions (
e.g.,
daylight hours; Beaufort sea state (BSS) 3 or less), PSOs should conduct observations when the acoustic source is not operating for comparison of sighting rates and behavior with and without use of the acoustic source and between acquisition periods.

Acoustic
—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. All source vessels shall carry a minimum of one experienced PAM operator. 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. We acknowledge generally that PAM has significant limitations. For example, animals may only be detected when vocalizing, species making directional vocalizations must vocalize towards the array to be detected, species identification and localization may be difficult, etc. However, we believe that for certain species and in appropriate environmental conditions it is a useful complement to visual monitoring during good sighting conditions and that it is the only meaningful monitoring technique during periods of poor visibility. Further detail regarding PAM system requirements may be found in the “Proposed Monitoring” 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. We do offer some specifications later in this document and each applicant has provided a PAM plan.

Following protocols described by the New Zealand Department of Conservation for seismic 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:

• Daylight hours and sea state is less than or equal to Beaufort sea state (BSS) 4;

• No marine mammals (excluding small delphinoids; 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.

As noted previously, all source vessels must carry a minimum of one experienced visual PSO and one experienced PAM operator. Although a given PSO may carry out either visual PSO or PAM operator duties during a survey (assuming appropriate training),

the required experienced PSOs may not be the same person. The observer designated as lead PSO (including the full team of visual PSOs and PAM operators) must be an experienced visual PSO. The applicant may determine how many PSOs are required to adequately fulfill the requirements specified here. To summarize, these requirements are: (1) Separate experienced visual PSOs and PAM operators; (2) 24-hour acoustic monitoring during use of the acoustic source; (3) visual monitoring during use of the acoustic source by two PSOs during all daylight hours and during nighttime ramp-ups; (4) 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 (5) maximum of 12 hours of observational effort per 24-hour period for any PSO, regardless of duties.

Buffer Zone and Exclusion Zone

The PSOs shall establish and monitor a 500-m exclusion zone and a 1,000-m buffer zone. 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 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. Dunlop
et al.
(2016) studied the effect of ramp-up during a seismic airgun survey on migrating humpback whales, finding that although behavioral response indicating potential avoidance was observed, there was no evidence that ramp-up was more effective at causing aversion than was a constant source. Regardless, the majority of whale groups did avoid the source vessel at distances greater than the radius of most mitigation zones (Dunlop
et al.,
2016). 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 assumed to be better than the alternative), ramp-up remains a relatively low cost, common sense component of standard mitigation. 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 not be less than 60 minutes prior to the planned ramp-up. A designated PSO must be notified again immediately prior to initiating ramp-up procedures and the operator must receive confirmation from the PSO to proceed.

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 be approximately 20 minutes. 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. These requirements may be modified on the basis of any new information presented that justifies a different protocol. 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 source activated prior to reaching the designated run-in. We adopt this approach to ramp-up (increments of array elements) because it is relatively simple to implement for the operator as compared with more complex schemes involving activation by increments of array volume, or activation on the basis of element location or size. Such approaches may also be more likely to result in irregular leaps in sound output due to variations in size between individual elements within an array and their geometric interaction as more elements are recruited. It may be argued whether smooth incremental increase is necessary, but stronger aversion than is necessary should be avoided. The approach proposed here 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 buffer zone 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 should be planned to occur during periods of good visibility when possible; operators should 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 should be reported by the lead PSO and would be investigated by NMFS. Ramp-up may not be initiated if any marine mammal (including small delphinoids) is within the designated buffer zone. If a marine mammal is observed within the buffer zone during the pre-clearance period, ramp-up may not begin until the animal(s) has been observed exiting the buffer 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 buffer zone during ramp-up, and ramp-up must cease and the source shut down upon observation of marine mammals within or approaching the buffer zone.

Exclusion Zone and Shutdown Requirements

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,

disruption of critical behaviors. The PSOs must establish a minimum exclusion zone with a 500 m radius as a perimeter around the airgun array (rather than being centered on the array or around the vessel itself). If a marine mammal appears within, enters, or appears on a course to enter 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).

This shutdown requirement is in place for all marine mammals, with the exception of small delphinoids under certain circumstances. As defined here, the small delphinoid group is intended to encompass those members of the Family Delphinidae most likely to voluntarily approach the source vessel for purposes of interacting with the vessel and/or airgun array (
e.g.,
bow riding). This exception to the shutdown requirement applies solely to specific genera of small dolphins—
Steno, Tursiops,

Stenella, Delphinus,

Lagenodelphis,
and
Lagenorhynchus
(see Table 4)—and only applies if the animals are traveling, including approaching the vessel. If, for example, an animal or group of animals is stationary for some reason (
e.g.,
feeding) and the source vessel approaches the animals, the shutdown requirement applies. An animal with sufficient incentive to remain in an area rather than avoid an otherwise aversive stimulus could either incur auditory injury or disruption of important behavior. If there is uncertainty regarding identification (
i.e.,
whether the observed animal(s) belongs to the group described above) or whether the animals are traveling, shutdown must be implemented. We do not require that a PSO determine the intent of the animal(s)—an inherently subjective proposition—but simply whether any potential intersection of the animal with the 500-m exclusion zone would be caused due to the vessel's approach towards relatively stationary animals.

We propose this small delphinoid exception because a shutdown requirement for small delphinoids under all circumstances is of known concern regarding practicability for the applicant due to increased shutdowns, without likely commensurate benefit for the animals in question. Small delphinoids are generally the most commonly observed marine mammals in the specific geographic region and would typically be the only marine mammals likely to intentionally approach the vessel. As described below, auditory injury is extremely unlikely to occur for mid-frequency cetaceans (
e.g.,
delphinids), as this group is relatively insensitive to sound produced at the predominant frequencies in an airgun pulse while also having a relatively high threshold for the onset of auditory injury (
i.e.,
permanent threshold shift). Please see “Potential Effects of the Specified Activity on Marine Mammals” later in this document for further discussion of sound metrics and thresholds and marine mammal hearing. A large body of anecdotal evidence indicates that small delphinoids commonly approach vessels and/or towed arrays during active sound production for purposes of bow riding, with no apparent effect observed in those delphinoids (
e.g.,
Barkaszi
et al.,
2012). The 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. Although other mid-frequency hearing specialists (
e.g.,
large delphinoids) are no more likely to incur auditory injury than are small delphinoids, they are much less likely to approach vessels. Therefore, retaining a shutdown requirement for large delphinoids would not have similar impacts in terms of either practicability for the applicant or corollary increase in sound energy output and time on the water. We do anticipate some benefit for a shutdown requirement for large delphinoids in that it simplifies somewhat the total array of decision-making for PSOs and may preclude any potential for physiological effects other than to the auditory system as well as some more severe behavioral reactions for any such animals in close proximity to the source vessel.

BOEM's PEIS (BOEM, 2014a) provided modeling results for auditory injury zones on the basis of auditory injury criteria described by Southall
et al.
(2007). These zones were less than 10 m on the basis of maximum peak pressure, and a maximum of 18 m on the basis of cumulative sound exposure level (including application of relevant M-weighting filters). However, the recent finalization of NMFS's new technical acoustic guidance made these predictions irrelevant (NMFS, 2016). We 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. These are as follows: Low-frequency cetaceans, 50-224 m; mid-frequency cetaceans, 14-63 m; and high-frequency cetaceans, 355-1,585 m. The 500-m radial distance of the standard exclusion zone is intended to be precautionary in the sense that it would be expected to contain sound exceeding peak pressure injury criteria for all hearing groups other than high-frequency cetaceans, while also 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.

An appropriate exclusion zone based on cumulative sound exposure level (cSEL) criteria would be dependent on the animal's applied hearing range and how that overlaps with the frequencies produced by the sound source of interest (
i.e.,
via marine mammal auditory weighting functions) (NMFS, 2016), and may be larger in some cases than the zones calculated on the basis of the peak pressure thresholds (and larger than 500 m) depending on the species in question and the characteristics of the specific airgun array. In particular, it is likely that exclusion zone radii would be larger for low-frequency cetaceans, because their most susceptible hearing range overlaps the low frequencies produced by airguns, but that the zones would remain very small for mid-frequency cetaceans (
i.e.,
including the “small delphinoids” described above), whose range of best hearing largely does not overlap with frequencies produced by airguns. In order to more realistically incorporate the technical guidance's weighting functions over a seismic 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). 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. These distances were smaller than those calculated on the basis of the peak pressure criterion, with the exception of the low-frequency cetacean hearing group (calculated zones range from 80-4,766 m). Therefore, our proposed 500-m exclusion zone contains the entirety of any potential injury zone for mid-frequency cetaceans, 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 proposed 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 propose a shutdown measure for
Kogia
spp. to address these potential injury concerns (described later in this section).

However, it is important to note that consideration of 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 consideration of peak pressure thresholds is most relevant, as compared with cumulative sound exposure level thresholds, as the latter requires that an animal accumulate some level of sound energy exposure over some period of time (
e.g.,
24 hours). 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. Therefore, definition of an exclusion zone based on cSEL thresholds is of questionable relevance given relative motion of the source and receiver (
i.e.,
the animal). Cumulative SEL thresholds are likely more relevant for purposes of modeling the potential for auditory injury than they are for informing real-time mitigation. 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 and high-frequency cetaceans, some potential auditory injury is likely impossible to mitigate and should be considered for authorization.

In summary, 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 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 would contain all potential auditory injury for mid-frequency cetaceans, would contain all potential auditory injury for both low- and mid-frequency cetaceans as assessed against peak pressure thresholds (NMFS, 2016), and 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 seismic 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).

Shutdown of the acoustic source is also required (at any distance) in other circumstances:

• Upon observation of a right whale at any distance. 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 (Kraus
et al.,
2005; Waring
et al.,
2016; Pettis and Hamilton, 2016). We believe it appropriate to eliminate potential effects to individual right whales to the extent possible.

• For TGS only, due to a high predicted amount of exposures (Table 10), we propose that shutdown be required upon observation of a fin whale at any distance. If the observed fin whale is within the behavioral harassment zone, it would still be considered to have experienced harassment, 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. This measure is not proposed for implementation by Spectrum, ION, CGG, or Western.

• Upon observation of a large whale (
i.e.,
sperm whale or any baleen whale) with calf at any distance, 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. Disturbance of cow-calf pairs, for example, could potentially result in separation of vulnerable calves from adults. Given the endangered status of most large whale species and the difficulty of correctly identifying some rorquals at greater distances, as well as the functional sensitivity of the mysticete whales to frequencies associated with the subject geophysical survey activity, we believe this measure is necessary.

• Upon observation of a diving sperm whale at any distance centered on the forward track of the source vessel. Disturbance of deep-diving species such as sperm whales could result in avoidance behavior such as diving and, given their diving capabilities, it is possible that the vessel's course could take it closer to the submerged animals. As noted by Weir and Dolman (2007), a whale diving ahead of the source vessel within 2 km may remain on the vessel trackline until the ship approaches the whale's position before beginning horizontal movement. If undetected by PAM, it is possible that a shutdown might not be triggered and a severe behavioral response caused.

• Upon any observation (visual or acoustic) of a beaked whale or
Kogia
spp. Similar to the sperm whale measure described above, these species are deep divers and it is possible that disturbance could provoke a severe behavioral response leading to injury. Unlike the sperm whale, 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. For

example, 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 (Barlow (1999) estimates such probabilities at 0.23 to 0.45 for Cuvier's and Mesoplodont beaked whales, respectively). 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 later in this document (see “Estimated Take by Incidental Harassment”), there are high levels of predicted exposures for beaked whales in particular. Because it is likely that only a small proportion of beaked whales and
Kogia
spp. potentially affected by the proposed surveys would actually be detected, it is important to avoid potential impacts when possible. Additionally for
Kogia
spp.—the one species of high-frequency cetacean likely to be encountered—auditory injury zones relative to peak pressure thresholds may range from approximately 350-1,500 m from the acoustic source, depending on the specific array characteristics (NMFS, 2016).

• Upon observation of an aggregation of marine mammals of any species that does not appear to be traveling. Under these circumstances, we assume that the animals are engaged in some important behavior (
e.g.,
feeding, socializing) that should not be disturbed. By convention, we define an aggregation as six or more animals. This definition may be modified on the basis of any new information presented that justifies a different assumption.

Any PSO on duty has the authority to delay the start of survey operations or to call for shutdown of the acoustic source (visual PSOs on duty should be in agreement on the need for delay or shutdown before requiring such action). 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. When only the PAM operator is on duty and a detection is made, if there is uncertainty regarding species identification or distance to the vocalizing animal(s), the acoustic source must be shut down as a precaution.

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 observation of the animal(s). Where there is no relevant zone (
e.g.,
shutdowns at any distance), a 30-minute clearance period must be observed following the last observation of the animal(s). We recognize that BOEM may require a longer clearance period (
e.g.,
60 minutes). However, at typical survey speed of approximately 4.5 kn, the vessel would cover greater than 4 km during the 30-minute clearance period. Although some deep-diving species are capable of remaining submerged for periods up to an hour, it is unlikely that they would do so both while experiencing potential adverse reaction to the acoustic stimulus and remaining within the exclusion zone of the moving vessel. Extending the clearance period would not appreciably increase the likelihood of detecting the animals prior to reactivating the acoustic source.

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 can be used either as a reverse ramp-up or may simply involve reducing the array to a single element or “mitigation source,” and has been allowed in past MMPA authorizations as a substitute for full shutdown. We address use of a mitigation source below. In a power-down scenario, it is assumed that turning off power to individual array elements reduces the size of the ensonified area such that an observed animal is then outside some designated area. However, we have no information as to the effect of powering down the array on the resulting sound field. In 2012, NMFS and BOEM held a monitoring and mitigation workshop focused on seismic survey activity. Industry representatives indicated that the end result may ultimately be increased sound input to the marine environment due to the need to re-shoot the trackline to prevent gaps in data acquisition (unpublished workshop report, 2012). For this reason and because a power-down may not actually be useful, our proposal requires full shutdown in all applicable circumstances; power-down is not allowed.

Mitigation Source

Mitigation sources may be separate individual airguns or may be an airgun of the smallest volume in the array, and are often used when the full array is not being used (
e.g.,
during line turns) in order to allow ramp-up during poor visibility. The general premise is that this lower-intensity source, if operated continuously, would be sufficiently aversive to marine mammals to ensure that they are not within an exclusion zone, and therefore, ramp-up may occur at times when pre-clearance visual watch is minimally effective. There is no information to suggest that this is an effective protective strategy, yet we are certain that this technique involves input of extraneous sound energy into the marine environment, even when use of the mitigation source is limited to some maximum time period. For these reasons, we do not believe use of the mitigation source is appropriate and do not propose to allow its use. However, as noted above, ramp-up may occur under periods of poor visibility assuming that no acoustic or visual detections are made during a 30-minute pre-clearance period. This is a change from how mitigation sources have been considered in the past in that the visual pre-clearance period is typically assumed to be highly effective during good visibility conditions and viewed as critical to avoiding auditory injury and, therefore, maintaining some likelihood of aversion through use of mitigation sources during poor visibility conditions is valuable.

In light of the available information, we think it more appropriate to acknowledge the limitations of visual observations—even under good

conditions, not all animals will be observed and cryptic species may not be observed at all—and recognize that while visual observation is a common sense mitigation measure its presence should not be determinative of when survey effort may occur. Given the lack of proven efficacy of visual observation in preventing auditory injury, its absence should not imply such potentially detrimental impacts on marine mammals, nor should use of a mitigation source be deemed a sensible substitute component of seismic mitigation protocols. We also believe that consideration of mitigation sources in the past has reflected an outdated balance, in which the possible prevention of relatively few instances of auditory injury is outweighed by many more instances of unnecessary behavioral disturbance of animals and degradation of acoustic habitat.

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 proposed IHAs; the operator must provide information to the lead PSO at regular intervals confirming the firing 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.

We encourage the applicant companies and operators to pursue the following objectives in designing, tuning, and operating acoustic sources: (1) Use the minimum amount of energy necessary to achieve operational objectives (
i.e.,
lowest practicable source level); (2) minimize horizontal propagation of sound energy; and (3) minimize the amount of energy at frequencies above those necessary for the purpose of the survey. However, we are not aware of available specific measures by which to achieve such certifications. In fact, BOEM recently announced that an expert panel convened 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, 2016b). Minimizing production of sound at frequencies higher than are necessary would likely require design, testing, and use of wholly different airguns than are proposed for use by the applicants. At minimum, 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.

There has been some attention paid to the establishment of minimum separation distances between operating source vessels, and BOEM may require a minimum 40-km geographic separation distance (BOEM, 2014b). The premise regarding this measure is either to provide a relatively noise-free corridor between vessels conducting simultaneous surveys such that animals may pass through rather than traveling larger distances to go around the source vessels or to reduce the cumulative sound exposure for an animal in a given location. There is no information supporting the effectiveness of this measure, and participants in a 2012 monitoring and mitigation workshop focused on seismic survey activity held by NMFS and BOEM were skeptical regarding potential efficacy of this measure (unpublished workshop report, 2012). Unintended consequences were a concern of some participants, including the possibility that converging sound fields could confuse animals and/or prevent egress from an area. In fact, it may be more effective as a protective measure to group acoustic sources as closely together as possible, in which case the SEL exposure would not be appreciably louder and an animal would have a better chance of avoiding exposure than through the supposed corridor (thus also potentially shortening total duration of sound exposure).

The desired effect of such a measure is too speculative and would impose additional burden on applicants. Therefore, we do not propose to require any minimum separation distance between source vessels. Operators do typically maintain a minimum separation of about 17.5 km between concurrent surveys to avoid interference (
i.e.,
overlapping reflections received from multiple source arrays) (BOEM, 2014a). As noted previously, TGS (the only company proposing to use two source vessels) plans to maintain a minimum separation of approximately 100 km between their own source vessels.

Closure Areas

Coastal Restriction
—No seismic 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 because they were determined to be below their 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). Already designated as depleted, an Unusual Mortality Event (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. A 10 km buffer is provided to encompass the area within which sound exceeding 160 dB rms would reasonably be expected to occur (see additional discussion in next section). Further discussion of this UME is provided under “Description of Marine Mammals in the Area of the Specified Activity,” later in this document.

The coastal form of bottlenose dolphin is known to occur further offshore than 20 km, but available information suggests that exclusion of harassing sound from a 20 km coastal zone would avoid the vast majority of impacts. There is generally a discontinuity in bottlenose dolphin distribution between nearshore areas inhabited by coastal ecotype dolphins and the deeper offshore waters inhabited by offshore ecotype dolphins (Kenney, 1990; Roberts
et al.,
2016), with some possibility that this discontinuity represents habitat partitioning between bottlenose dolphins and Atlantic spotted dolphins (which occur in high density on the shelf in areas where there is generally low density of bottlenose dolphin). The separation between offshore and coastal morphotypes varies depending on location and season, with the ranges overlapping to some degree south of Cape Hatteras. Coastwide, systematic biopsy collection surveys were conducted during the summer and winter to evaluate the degree of spatial overlap between the two morphotypes. North of Cape Lookout, North Carolina, there was a clear discontinuity with coastal ecotype dolphins found in waters less than 20 m depth and offshore ecotype dolphins found in waters greater than 40 m depth. South of Cape Lookout, spatial overlap was

found although the probability of a sampled group being from the coastal ecotype decreased with increasing depth (Garrison
et al.,
2003). Prior to these surveys, coastal ecotype dolphins were provisionally assumed to occur within a spatial boundary of 27 km from shore for the region south of Cape Hatteras during winter and a boundary of 12 km from shore for the region north of Cape Hatteras during summer (Garrison, 2001 in Garrison
et al.,
2003). Here, we adopt a coastwide 20 km spatial boundary for simplicity and under the assumption that it would contain the vast majority of coastal bottlenose dolphins.

Proposal of this measure should not be interpreted as NMFS's determination that harassment of coastal bottlenose dolphins cannot be authorized. However, when considering the likely benefit to the species against the impact to applicants, we believe that inclusion of this measure is warranted. Approximately 1,650 dolphin carcasses were recovered during the UME, and it is likely that many more dolphins died whose carcasses were not recovered. Considering just the known dead could represent greater than five percent of the pre-UME abundance for all coastal ecotype dolphins within the affected area. Ongoing areas of research related to the UME include understanding its impacts on the status of the affected stocks, as well as continuing monitoring and modeling designed to inform understanding of impacts on the surviving population. Given this uncertainty, a precautionary approach is warranted. We note that three applicants, Spectrum, CGG, and Western, do not propose to conduct survey effort within 30 km of the coast, and effort within 30 km for the other two applicants would represent a small fraction of overall survey effort.

North Atlantic Right Whale
—We propose seasonal restriction of survey effort such that particular areas of expected importance for North Atlantic right whales are not ensonified by levels of sound expected to result in behavioral harassment, including designated critical habitat, vessel speed limit seasonal management areas (SMAs), a coastal strip containing SMAs, and vessel speed limit dynamic management areas (DMAs). Although right whales may also use areas farther offshore, these areas are expected to provide substantial protection of right whales within the migratory corridor and calving and nursery grounds and, when coupled with the absolute shutdown provision described previously for right whales, may reasonably be expected to eliminate most potential for behavioral harassment of right whales.

The North Atlantic right whale was severely depleted by historical whaling, and currently has a small population abundance (
i.e.,
less than 500 individuals) that is considered to be extremely low relative to the optimum sustainable population (Waring
et al.,
2016). Surveys in recent years have detected an important shift in habitat use patterns, with fewer whales observed in feeding areas and counts for calves and adults on the southeastern calving grounds the lowest recorded since those surveys began (Waring
et al.,
2016). At the same time, the current estimate of the minimum number of whales alive (as described in NMFS's draft 2016 stock assessment report) suggests that abundance has declined. While the authors caution that this apparent decrease should be interpreted with caution and in conjunction with apparent shifts in habitat use, it is possible that the population has declined. An increased number of carcasses were recovered in 2004-05, including six adult females. Kraus
et al.
(2005) determined that this mortality rate increase would reduce population growth by approximately ten percent per year, a trend not detected in subsequent years. Furthermore, the current annual estimate of anthropogenic mortality is over five times the potential biological removal level (see “Description of Marine Mammals in the Area of the Specified Activity” for further discussion of these concepts). The small population size and low annual reproductive rate of right whales suggest that human sources of mortality may have a greater effect relative to population growth rates than for other whales (Waring
et al.,
2016). Given these considerations, and the likelihood that any disturbance of right whales is consequential, here we take a precautionary approach to mitigation.

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). However, as a precautionary approach all areas discussed here for proposed mitigation would be in effect from November 1 through April 30. Because we intend to use these areas to reduce the likelihood of exposing right whales to noise from airgun arrays that might result in harassment, we require that source vessels maintain a minimum standoff of 10 km from the area. 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. Restricting scenario results to fall/winter and water depths <1,000 m reduces the number of relevant scenarios to six, with the range of radial distances from 8,083-8,896 m (mean of 8,454 m).

BILLING CODE 3510-22-P

EN06JN17.001

BILLING CODE 3510-22-C

The portion of critical habitat within the proposed survey area includes nearshore and offshore waters of the southeastern U.S., extending from Cape Fear, North Carolina south to 28° N. The specific area designated as critical habitat, as defined by regulation (81 FR 4838; January 27, 2016), is demarcated by rhumb lines connecting the specific points identified in Table 2. This area is depicted in Figure 2, and the restriction on survey effort within 10 km of this area would be in effect from November

through April, when right whales are known to use the area.

A coastal strip containing all SMAs would also be avoided by a minimum standoff distance of 10 km, as would DMAs. These are areas in which right whales are likely to be present when such areas are in effect; mandatory or voluntary speed restrictions for certain vessels are in place in these areas respectively when in effect to reduce the risk of ship strike. Because these areas are intended to reduce the risk of ship strike involving right whales, they are designated in consideration of both right whale presence during migratory periods and commercial shipping traffic. Our concern is not limited to ship strike; therefore the standoff areas based on the SMAs are extended to a continuous coastal strip with a 10 km buffer. Mid-Atlantic SMAs (from Delaware to northern Georgia) are intended to protect whales on the migratory route and are generally defined as a 20 nmi (37 km) radial distance around the entrance to certain ports. Therefore, no survey effort may occur within 47 km of the coast between November and April. This strip is superseded where either designated critical habitat or the southeast SMA provides a larger restricted area. The southeast SMA, intended to protect whales on the calving and nursery grounds, includes the area bounded to the north by 31°27′ N., to the south by 29°45′ N., and to the east by 80°51′36″ W. No survey effort may occur within 10 km of this area between November and April. The combined area of our proposed restriction—composed of the greater of designated critical habitat, the 20 nmi coastal strip, and the southeastern SMA (all buffered by 10 km)—is depicted in Figure 3.

Table 2—Boundaries of Designated Critical Habitat for North Atlantic Right Whales

Latitude
Longitude
Latitude
Longitude

33°51′ N.
At shoreline
29°08′ N.
80°51′ W.

33°42′ N.
77°43′ W.
28°50′ N.
80°39′ W.

33°37′ N.
77°47′ W.
28°38′ N.
80°30′ W.

33°28′ N.
78°33′ W.
28°28′ N.
80°26′ W.

32°59′ N.
78°50′ W.
28°24′ N.
80°27′ W.

32°17′ N.
79°53′ W.
28°21′ N.
80°31′ W.

31°31′ N.
80°33′ W.
28°16′ N.
80°31′ W.

30°43′ N.
80°49′ W.
28°11′ N.
80°33′ W.

30°30′ N.
81°01′ W.
28°00′ N.
80°29′ W.

29°45′ N.
81°01′ W.
28°00′ N.
At shoreline.

29°15′ N.
80°55′ W.

Reproduced from 50 CFR 226.203(b)(2).

DMAs are also 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.

BILLING CODE 3510-22-P

EN06JN17.002

BILLING CODE 3510-22-C
Designation of DMAs follows certain protocols identified in 73 FR 60173 (October 10, 2008):

1. A circle with a radius of at least 3 nmi (5.6 km) is drawn around each observed group. This radius is adjusted for the number of right whales seen in the group such that the density of four right whales per 100 nmi
2
(185 km
2
) is maintained. The length of the radius is determined by taking the inverse of the four right whales per 100 nmi
2
density (24 nmi
2
per whale). That figure is

equivalent to an effective radial distance of 3 nmi for a single right whale sighted, 4 nmi for two whales, 5 nmi for three whales, etc.

2. If any circle or group of contiguous circles includes three or more right whales, this core area and its surrounding waters become a candidate temporary zone. After NMFS identifies a core area containing three or more right whales, as described here, it will expand this initial core area to provide a buffer area in which the right whales could move and still be protected.

NMFS determines the extent of the DMA zone by:

3. Establishing a 15-nmi (27.8-km) radius from the sighting location used to draw a larger circular zone around each core area encompassing a concentration of right whales. The sighting location is the geographic center of all sightings on the first day of an event; and

4. Identifying latitude and longitude lines drawn outside but tangential to the circular buffer zone(s).

NMFS issues announcements of DMAs to mariners via its customary maritime communication media (
e.g.,
NOAA Weather radio, Web sites, 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 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.

Proposal of this measure should not be interpreted as NMFS's determination that harassment of right whales cannot be authorized. However, when considering the current status of the species, likely benefit of the measure to the species, and likely impact to applicants, we believe that inclusion of this measure is warranted.

Other Species
—Predicted acoustic exposures are moderate to high for certain potentially affected marine mammal species (see Table 10) and, regardless of the absolute numbers of predicted exposures, the scope of proposed activities (
i.e.,
proposed 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 3). Our qualitative assessment leads us to believe that implementation of these measures is expected to provide both meaningful control on the numbers of animals affected as well as 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”), Atlantic spotted dolphin, and pilot whales. For all four species or guilds, the amount of predicted exposures is moderate to high. For the Atlantic spotted dolphin, our impetus in delineating a restriction on survey effort is solely due to this high amount of predicted exposures to survey noise. For other species, 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 proposed 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 #5 (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 #2-4 (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.

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 proposed 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. Please see “Marine Mammal Density Information,” later in this document, for a full description of the density models. 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. The purpose of a core abundance area is to represent the smallest area containing some percentage of the predicted abundance of each species. Summing all the cells (pixels) in the species distribution product gives the total predicted abundance. Core area is calculated by ranking cells by their abundance value from greatest to least, then summing cells with the highest abundance values until the total is equal to or greater than the specified percentage of the total predicted abundance. For example, if a 50 percent core abundance area is produced, half of the predicted abundance falls within the identified core area, and half occurs outside of it. In creating core abundance areas, we considered data outputs over the entire Atlantic coast scale rather than limiting to the proposed survey areas. This is appropriate because we are concerned with impacts to a stock as a whole, and therefore were interested in core abundance based on total predicted abundance rather than just abundance predicted over some subset of a stock's range. 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.

To determine core abundance areas, we follow a three-step process:

• Determine the predicted total abundance of a species/time period by adding up all cells of the density raster (grid) for the species/time period. For the Roberts
et al.
(2016) density rasters, density is specified as the number of animals per 100 km
2
cell.

• Sort the cells of the species/time period density raster from highest density to the lowest.

• Sum and select the raster cells from highest to lowest until a certain percentage of the total abundance is reached.

The selected cells represent the smallest area that represents a given percentage of abundance. We created a range of core abundance areas for each species of interest, but ultimately determined that 25 percent core abundance area was appropriate in most cases for our purpose. The larger the percentage of abundance captured, the larger the area. Generally speaking, we found that 25 percent core abundance provided the best balance between the areas given by larger (impracticably large areas for purposes of restricting survey effort) and smaller (ineffective areas for purposes of providing meaningful protection) areas. However, for sperm whales, our analysis showed that the 25 percent core abundance area covered a large portion of slope waters in the northern mid-Atlantic region and, therefore, what we believe to be an impracticably large area for potential restriction of survey effort. Although sperm whales are broadly distributed on the slope throughout the year, at the five percent core abundance threshold we found that the model predictions indicate a relatively restricted area of preferred habitat across all seasons in the vicinity of the shelf break to the north of Cape Hatteras. This area, 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 proposed time-space restriction for sperm whales. Core abundance maps are provided online at
www.nmfs.noaa.gov/pr/permits/incidental/oilgas.htm.

In summary, we propose the following closure areas (depicted in Figure 4):

• 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.

• An area proposed for protection of the North Atlantic right whale (Figure 3). The area is comprised of the furthest extent at any location of three distinct components: (1) A 47-km coastal strip (20-nmi plus 10 km buffer) throughout the entire Mid- and South Atlantic OCS planning areas; (2) designated critical habitat, buffered by 10 km; and (3) the designated southeastern seasonal management area, buffered by 10 km. This area would be closed to use of the acoustic source from November through April. Dynamic management areas (buffered by 10 km) are also closed to use of the acoustic source when in effect.

The 10-km buffer (intended to reasonably prevent sound output from the acoustic source exceeding received levels expected to result in behavioral harassment from entering the proposed closure areas) is built into the areas defined below and in Table 3. Therefore, we do not separately mention the addition of the buffer.

BILLING CODE 3510-22-P

EN06JN17.003

BILLING CODE 3510-22-C
• An area proposed for protection of Atlantic spotted dolphin (Area #1, Figure 4). The area contains the on-shelf portion of a 25 percent core abundance area for the species, and is comprised of lines that demarcate the northern and southern extent of this area, connected by a line marking 100 km distance from shore (as indicated in Table 3). This area would be closed to use of the acoustic source from June through August. This restriction would not be required for ION or CGG.

• Deepwater canyon areas. Areas #2-4 (Figure 4) are proposed as defined in Table 3 and would be closed to use of

the acoustic source year-round. Although they may be protective of additional species (
e.g., Kogia
spp.), Area #2 is expected to be particularly beneficial for beaked whales and Areas #3-4 are expected to be particularly beneficial for both beaked whales and sperm whales.

• Shelf break off Cape Hatteras and to the north, including slope waters around “The Point.” Area #5 is proposed as defined in Table 3 and would be closed to use of the acoustic source from July through September. Although this closure is expected to be beneficial for a diverse species assemblage, Area #5 is expected to be particularly beneficial for beaked whales, sperm whales, and pilot whales.

Beaked Whale

Beaked whales are typically deep divers, foraging for mesopelagic squid and fish, and are often found in deep water near high-relief bathymetric features, such as slopes, canyons, and escarpments where these prey are found (
e.g.,
Madsen
et al.,
2014; MacLeod and D'Amico, 2006; Moors-Murphy, 2014). Sightings of Cuvier's beaked whale are almost exclusively in the continental shelf edge and continental slope areas, while
Mesoplodon
spp. sightings have occurred principally along the shelf-edge and deeper oceanic waters (CETAP, 1982; Waring
et al.,
1992; Tove, 1995; Waring
et al.,
2001; Hamazaki, 2002; Palka, 2006; Waring
et al.,
2014). Roberts
et al.
(2016)'s results suggest that beaked whales do not undertake large seasonal migrations, and are therefore associated with significant habitat features year-round or with some degree of residency (Roberts
et al.,
2015l; Gowans
et al.,
2000; MacLeod and D'Amico, 2006). In support of patterns seen in the density model outputs, MacLeod and D'Amico (2006) state that beaked whale occurrence is linked particularly to features such as slopes, canyons, escarpments and oceanic islands. Northern bottlenose whales and Sowerby's beaked whales were found to preferentially occur in a marine canyon rather than the neighboring shelf, slope and abyssal areas (Hooker
et al.,
1999, 2002). Cuvier's beaked whales are also known to associate with canyons (D'Amico
et al.,
2003; Williams
et al.,
1999), and Blainville's beaked whales were also found to preferentially occur over the upper reaches of a canyon (MacLeod and Zuur, 2005). Sighting rates of beaked whales in the western North Atlantic are significantly higher within canyon areas than non-canyon areas (Waring
et al.,
2001). It is possible, however, that such occurrence patterns are linked more strongly to oceanographic features influencing prey distribution, which may or may not be permanently linked to seabed topography (MacLeod and D'Amico, 2006).

Submarine canyons are important features of the shelf and slope region from Cape Hatteras to the north, with both major and minor canyons abundant in the region. Roberts
et al.
(2016) predicted beaked whale density at year-round temporal resolution, with model predictions showing concentrated distribution in deep waters over high-relief bathymetry where high prey density would be expected due to entrainment of nutrient-rich sediments and organic material (Moors-Murphy, 2014). Highest densities were predicted in areas along the continental slope and in and around submarine canyons (Roberts
et al.,
2016). The core abundance area analysis highlighted three such submarine canyon areas as being of year-round importance to beaked whales (Areas #2-4, see Figure 4). Area #3 is centered on Hatteras Canyon, a major canyon system that cuts a deep valley across the upper continental rise before terminating on the lower rise. Area #2, in deeper water, encompasses the Hatteras Transverse Canyon (HTC). HTC is downslope of and fed by both Hatteras and Albemarle Canyons (which dissect the slope) and their channel extensions, as well as smaller unnamed canyons and canyon channels, and is bounded by the Hatteras Ridge, which is a major transverse barrier deflecting turbidity currents into the HTC (Gardner
et al.,
2016). Area #4 is centered on a large, deepwater valley system that is fed by a complex series of canyons and gullies incising the slope between Hendrickson and Baltimore Canyons (note that the entire shelf break north of Cape Hatteras, including many of these canyons and gullies, is included in our Area #5 (Figure 4) which is discussed below). In delineating the actual area proposed for restriction on survey effort, we expanded from 10 x 10 km grid cells specifically predicted as being within the beaked whale 25 percent core abundance area to include adjacent cells that also cover the relevant bathymetric feature. Assuming that beaked whales are present in these areas, their use of these habitat areas would not be expected to be restricted within the feature and we delineate the proposed closure areas accordingly. We assume that beaked whales associate with these features year-round, and each of the three areas is proposed as a year-round closure.

Area #5 (Figure 4) was designed as a multi-species area, primarily focused on pilot whales, beaked whales, and sperm whales. This area is focused on a particularly dynamic and highly productive environment off of Cape Hatteras (sometimes referred to as “Hatteras Corner” or “The Point”) and the shelf break environment running to the north (to the boundary of BOEM's Mid-Atlantic OCS planning area) and to the south. This environment off of Cape Hatteras is created through the confluence of multiple currents and water masses, including the Gulf Stream (SAFMC, 2003), over complex bottom topography and hosts a high density and diversity of cetaceans (
e.g.,
McAlarney
et al.,
2015). For beaked whales, our core abundance area analysis predicts that the shelf break area running from The Point to the southern extent of Area #5 would be within the 25 percent core abundance area, while the remainder of the shelf break to the north would be within the 50 percent core abundance area. This finding is supported by passive acoustic monitoring effort, which detected echolocation signals from Cuvier's beaked whales consistently throughout the year (95 percent of 741 recording days across all seasons), suggesting that beaked whales are resident to this area (Stanistreet
et al.,
2015). Gervais' beaked whales were detected more sporadically (33 percent of recording days). Monthly aerial surveys conducted from 2011-2014 in the same region, from shallow continental shelf waters across the continental shelf break and into deep pelagic waters, also detected beaked whales in all months of the year (McLellan
et al.,
2015). All beaked whale sightings occurred along the continental shelf break. Baird
et al.
(2015) reported results from three tagged Cuvier's beaked whales, which largely remained in slope waters off the coasts of North Carolina, Virginia, and Maryland. Although this limited number of tags makes it difficult to draw conclusions, the authors hypothesize that the observed movements may be representative of a resident population.

Although beaked whales are likely present in this area year-round, there is significant overlap between this proposed restriction and the area of highest interest by the applicant companies. Therefore, we determined that practicability concerns dictate that we establish a temporal component to this closure rather than designate this area as a year-round closure (as is the case for Areas #2-4). Roberts
et al.
(2016) predicted density for pilot whales and beaked whales at year-round

temporal resolution; therefore, the output of those models does not help to designate a temporal aspect to this proposed restriction. However, the model produced for sperm whales predicts density at a monthly resolution and informed our delineation of temporal bounds for this closure. The model predicts the greatest density of sperm whales in this region from June through October, with the highest overall abundance predicted for July through September (Roberts
et al.,
2015n). Therefore, we propose that Area #5 be in effect as a seasonal area closure from July through September.

Sperm Whale

Although sperm whales are one of the most widely distributed marine mammals, they are typically more abundant in areas of high primary productivity (Jaquet
et al.,
1996) and thus may be expected to occur in greater numbers in areas where physiographic and oceanographic features serve to aggregate prey (
e.g.,
squid). Sperm whales are in fact commonly associated with submarine canyons (Moors-Murphy, 2014) and, specifically in this region, have been found to be associated with canyons (Whitehead
et al.,
1992), the north wall of the Gulf Stream (Waring
et al.,
1993), and temperature fronts and warm-core eddies (Waring
et al.,
2001; Griffin, 1999). Areas #3-4 (Figure 4), described above for beaked whales, were also identified as areas of high predicted density for sperm whales. Roberts
et al.
(2016) predicted sperm whale density at monthly temporal resolution, and core abundance analysis conducted at a monthly time-step predicts that Area #3 is of year-round importance for sperm whales, while Area #4 is within the sperm whale 25 percent core abundance area for seven months of the year (Jun-Dec). CETAP (1982) reported sightings of sperm whales north of Cape Hatteras off the shelf and along the shelf break during all four seasons, while acoustic monitoring detected sperm whales every month of the year off the shelf near Onslow Bay, North Carolina (Stanistreet
et al.,
2012; Hodge and Read, 2014; Debich
et al.,
2014; Hodge
et al.,
2015).

As noted above, Area #5 (Figure 4) is a multi-species area, primarily focused on pilot whales, beaked whales, and sperm whales, and is proposed to be in effect from July through September. In particular, Area #5's “bulge” to the north and east of Cape Hatteras was indicated as high-density sperm whale habitat contained within the five percent core abundance area in all months, but as a larger area and with higher predicted density during July through September, as discussed above. During these months, the 25 percent core abundance area for sperm whales is predicted as covering a large swath of the region from the region of The Point off and to the south of Cape Hatteras north to the planning area boundary and including shelf break waters east over the entire slope and into abyssal waters in some locations. As described previously, due to the large size of this area, we based this component of Area #5 on the relevant portion of the five percent core abundance are for sperm whales. This area, predicted to host the highest density of sperm whales, was contiguous to and somewhat overlapping with the shelf break strip suggested by core abundance area analysis for beaked whales and pilot whales. We believe this reflects the appropriate balance between necessary protective measures for this species and practic

[Text truncated at 120,000 characters. The full text is on the page linked above.]

---

Source: Frix Law Library, https://www.frixlaw.com/law-library/documents/fr%3A2017-11542. Public record. Not legal advice.