# Takes of Marine Mammals Incidental to Specified Activities: Taking Marine Mammals Incidental to U.S. Navy Surveillance Towed Array Sensor System Low Frequency Active Sonar Training and Testing in the Central and Western North Pacific Ocean and Eastern Indian Ocean

> Briefs, arguments, decisions, and more.

URL: https://www.frixlaw.com/law-library/documents/fr%3A2019-16695

## Record

- **Collection:** Federal Register
- **Document type:** Rule
- **Published:** August 13, 2019
- **Citation:** 84 FR 40132

## Text

DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
50 CFR Part 218
[190731-0008]
RIN 0648-BI42
Takes of Marine Mammals Incidental to Specified Activities: Taking Marine Mammals Incidental to U.S. Navy Surveillance Towed Array Sensor System Low Frequency Active Sonar Training and Testing in the Central and Western North Pacific Ocean and Eastern Indian Ocean

AGENCY:

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

ACTION:

Final rule; notification of issuance of Letter of Authorization.

SUMMARY:

NMFS, upon request from the U.S. Navy (Navy) issues these regulations pursuant to the Marine Mammal Protection Act (MMPA) to govern the taking of marine mammals incidental to the use of Surveillance Towed Array Sensor System Low Frequency Active (SURTASS LFA) sonar systems onboard U.S. Navy surveillance ships for training and testing activities conducted under the authority of the Secretary of the Navy in the western and central North Pacific Ocean and eastern Indian Ocean (SURTASS LFA sonar activities) beginning August 2019. These regulations, which allow for the issuance of a Letter of Authorization (LOA) for the incidental take of marine mammals during the described activities and timeframes, prescribe the permissible methods of taking and other means of effecting the least practicable adverse impact on marine mammal species or stocks and their habitat, and establish requirements pertaining to the monitoring and reporting of such taking.

DATES:

Effective on August 12, 2019, through August 11, 2026.

ADDRESSES:

A copy of the Navy's application and supporting documents, as well as a list of the references cited in this document, may be obtained online at:
www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-military-readiness-activities.
In case of problems accessing these documents, please call the contact listed below (see
FOR FURTHER INFORMATION CONTACT
).

FOR FURTHER INFORMATION CONTACT:

Wendy Piniak, Office of Protected Resources, NMFS, (301) 427-8401.

SUPPLEMENTARY INFORMATION:

Purpose for Regulatory Action

These regulations, issued under the authority of the MMPA (16 U.S.C. 1361
et seq.
), establish a framework for authorizing the take of marine mammals incidental to the Navy's use of SURTASS LFA sonar systems onboard U.S. Navy surveillance ships for training and testing activities (categorized as military readiness activities) conducted under the authority of the Secretary of the Navy in the western and central North Pacific Ocean and eastern Indian Ocean.

NMFS received an application from the Navy requesting regulations and an associated letter of authorization (LOA) to take individuals of multiple species and stocks of marine mammals (“Navy's rulemaking/LOA application” or “Navy's application”) by Level B harassment incidental to SURTASS LFA sonar activities. Please see “Background” below for definitions of harassment. This final rule establishes a framework under the authority of the MMPA (16 U.S.C. 1361
et seq.
) to allow for the authorization of take of marine mammals incidental to the Navy's specified activities.

Legal Authority for the Final Action

Section 101(a)(5)(A) of the MMPA (16 U.S.C. 1371(a)(5)(A)) generally directs 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 for up to five years if, after notice and public comment, the agency makes certain findings and issues regulations that set forth permissible methods of taking and other means of effecting the least practicable adverse impact (LPAI) on the affected species or stocks and their habitat, as well as monitoring and reporting requirements. Section 101(a)(5)(A) of the MMPA and the implementing regulations at 50 CFR part 216, subpart I provide the legal basis for issuing this final rule and any associated LOAs. As described in the
Background
section, the MMPA has been amended in a number of ways when the specified activity is a military readiness activity, including most recently in 2018 to extend the maximum authorization period under section 101(a)(5)(A) from five to seven years for Department of Defense military readiness activities. As directed by this legal authority, this final rule contains mitigation, monitoring, and reporting requirements.

Background

The MMPA prohibits the “take” of marine mammals, with certain exceptions. Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361
et seq.
) direct the Secretary of Commerce (as delegated to NMFS) to allow, upon request, the incidental, but not intentional, taking of small numbers of marine mammals by U.S. citizens who engage in a specified activity (other than commercial fishing) within a specified geographical region if certain findings are made and either regulations are issued or, if the taking is limited to harassment, an incidental harassment authorization may be issued following notice and opportunity for public comment.

Authorization for incidental takings shall be granted if NMFS finds that the taking will have a negligible impact on the species or stock(s) and will not have an unmitigable adverse impact on the availability of the species or stock(s) for taking for subsistence uses (where relevant). Further, NMFS must prescribe the permissible methods of taking and other means of effecting the least practicable adverse impact on the affected species or stocks and their habitat, paying particular attention to rookeries, mating grounds, and areas of similar significance, and on the availability of such species or stocks for taking for certain subsistence uses (referred to in shorthand as “mitigation”), and requirements pertaining to the monitoring and reporting of such takings.

The 2004 NDAA (Pub. L. 108-136) removed the “small numbers” and “specified geographical region” limitations indicated above and amended the definition of “harassment” as it applies to a “military readiness activity” to read as follows (Section 3(18)(B) of the MMPA): (i) Any act that injures or has the significant potential to injure a marine mammal or marine mammal stock in the wild (Level A Harassment); or (ii) Any act that disturbs or is likely to disturb a marine mammal or marine mammal stock in the wild by causing disruption of natural behavioral patterns, including, but not limited to, migration, surfacing, nursing, breeding, feeding, or sheltering, to a point where such behavioral patterns are abandoned or significantly altered (Level B Harassment). In addition, the FY 2004 NDAA amended the MMPA as it relates to military readiness activities and the incidental take authorization (ITA) process such that “least practicable adverse impact” shall include consideration of personnel safety, practicality of implementation,

and impact on the effectiveness of the military readiness activity. As mentioned above, the NDAA for FY 2019 amended the MMPA to extend the period of permitted incidental takings of marine mammals covered by section 101(a)(5)(A) in the course of specified military readiness activities from five to seven years.

The authorization of incidental taking under section 101(a)(5)(A) requires promulgation of activity-specific regulations following notice and opportunity for public comment. Under NMFS' implementing regulations for section 101(a)(5)(A), a Letter of Authorization (LOA) also is required to conduct activities pursuant to any activity-specific regulations (50 CFR 216.106).

Summary of Request

On June 4, 2018, NMFS received a request from the Navy for authorization to take, by Level B harassment, 46 species of marine mammals incidental to the use of SURTASS LFA sonar onboard U.S. Navy surveillance ships for training and testing activities (categorized as military readiness activities) conducted under the authority of the Secretary of the Navy in the western and central North Pacific Ocean and eastern Indian Ocean beginning in August 2019 and extending to August 2026. On July 13, 2018, NMFS published a notice of receipt (NOR) of the Navy's application in the
Federal Register
(83 FR 32615), and requested comments and information related to the Navy's request. The review and comment period for the NOR ended on August 13, 2018. The Navy submitted a revised application on November 13, 2018, that included a minor change to the mitigation measures provided in the June 2018 application. On March 1, 2019, NMFS published a notice of proposed rulemaking in the
Federal Register
(84 FR 7186), and requested comments and information related to the Navy's request. The review and comment period for the proposed rule ended on April 1, 2019. One comment received during the NOR comment period was addressed in the Proposed Rule, and comments received during the proposed rulemaking comment period are addressed in this final rule. See further details addressing comments received in the
Comments and Responses
section.

The Navy states, and NMFS concurs, that these SURTASS LFA sonar activities, classified as military readiness activities, may incidentally take marine mammals by exposing them to SURTASS LFA sonar at levels that constitute Level B harassment as defined above. The Navy requests authorization to take, by Level B Harassment, individuals from 139 stocks of 46 species of marine mammals (10 species of mysticete (baleen) whales, 31 species of odontocete (toothed) whales, and 5 species of pinnipeds (seals and sea lions)). This rule also covers the authorization of take of animals from additional associated stocks of marine mammals not listed here, should one or more of the stocks identified in this rule be formally separated into multiple stocks, provided NMFS is able to confirm the necessary findings for the newly identified stocks. As discussed later in this document, incidental takes due to SURTASS LFA sonar will be limited to Level B harassment. No takes by Level A harassment are authorized, as Level A harassment is considered unlikely and will be avoided through the implementation of the Navy's mitigation measures, as discussed below.

In previous SURTASS LFA sonar rulemakings, NMFS authorized some Level A harassment takes in an abundance of caution even though Level A harassment takes were not anticipated. However, to the knowledge of the Navy and NMFS, no Level A harassment takes have resulted over the 17-year history of SURTASS LFA sonar activities. Additionally, the exposure criteria and thresholds for assessing Level A harassment have been modified since prior rules based on the best available science. Under these new metrics, the zone for potential injury is substantially reduced. Therefore, due to the small injury zones and the fact that mitigation measures would ensure that marine mammals would not be exposed to received levels associated with injury, the Navy has not requested authorization for Level A harassment takes, and NMFS is not authorizing any takes by Level A harassment.

NMFS published the first incidental take rule for SURTASS LFA sonar, effective from August 2002 through August 2007, on July 16, 2002 (67 FR 46712); the second rule, effective from August 2007 through August 2012, on August 21, 2007 (72 FR 46846); and the third rule, effective from August 2012 through August 2017, on August 20, 2012 (77 FR 50290).

In 2016, the Navy submitted an application for a fourth incidental take regulation under the MMPA (DoN, 2016) for the taking of marine mammals by harassment incidental to the deployment of up to four SURTASS LFA sonar systems from August 15, 2017, through August 14, 2022. NMFS published a proposed rule on April 27, 2017 (82 FR 19460). On August 10, 2017, the Deputy Secretary of Defense, after conferring with the Secretary of Commerce, determined that it was necessary for the national defense to exempt all military readiness activities that use SURTASS LFA sonar from compliance with the requirements of the MMPA for a period of up to two years beginning August 13, 2017, through August 12, 2019, or until such time when NMFS issues regulations and an LOA under MMPA section 101(a)(5)(A) for military readiness activities associated with the use of SURTASS LFA sonar, whichever is earlier. During the period of the National Defense Exemption (NDE) (available at
http://www.surtass-lfa-eis.com/wp-content/uploads/2018/01/SURTASS_LFA_NDE_10Aug17.pdf
), all military readiness activities that involve the use of SURTASS LFA sonar were required to comply with all mitigation, monitoring, and reporting measures set forth in the NDE for SURTASS LFA sonar, which were based on the measures included in NMFS' prior (2012) final rule (77 FR 50290; August 20, 2012) and 2017 proposed rule (82 FR 19460; April 27, 2017). As a result of the NDE, NMFS did not finalize its April 2017 proposed rule.

The NDE expires August 12, 2019. For this rulemaking, the Navy will continue to use SURTASS LFA sonar systems onboard United States Naval Ship (USNS) surveillance ships for training and testing activities conducted under the authority of the Secretary of the Navy within the western and central North Pacific Ocean and eastern Indian Ocean. The operating features of the LFA sonar will remain, and have remained the same since the 2001 SURTASS LFA FOEIS/EIS. The typical duty cycle of LFA sonar, based on historical SURTASS LFA sonar use, is 7.5 to 10 percent (DoN, 2007). The maximum duty cycle remains the same at 20 percent.

For this rulemaking, the Navy scoped the geographic extent of the area where the specified activity will occur (Study Area) to better reflect the areas where the Navy anticipates conducting SURTASS LFA sonar training and testing activities. Whereas the previous authorizations included certain routine military operations among the scope of actions analyzed, the Navy also has narrowed the scope of activities in the current request for authorization to training and testing activities only, due to various statutory and practical considerations, as described in Chapter 1 of the 2019 SURTASS LFA FSEIS/SOEIS, and discussed further below.

The Navy will transmit a total of up to 496 LFA sonar transmission hours

per year for its specified activity, as described below (see
Description of the Specified Activities
section), pooled across all SURTASS LFA sonar-equipped vessels in the first four years of the authorization, with an increase in usage to a total of up to 592 LFA transmission hours in years five through seven.

Changes From the Proposed to the Final Rule

Since the proposed rule, based on public comment and additional analysis, NMFS and the Navy have agreed to additional mitigation and monitoring measures that are expected to reduce the likelihood and/or severity of adverse impacts on marine mammal species/stocks and their habitat and are practicable for implementation.

• In the proposed rule we presented 25 marine areas for further consideration as marine mammal Offshore Biologically Important Areas (OBIAs) for SURTASS LFA sonar. After considering public comments and conducting additional analyses, 33 marine areas were assessed as potential OBIAs. Of these 33 marine areas, 17 were determined to qualify as OBIAs. All 17 of the areas were found to be practicable and were designated as 14 OBIAs (some OBIAs encompass several marine areas). All four of the OBIAs previously designated in the SURTASS LFA sonar Study Area have been expanded spatially.

• The Navy will use no more than 25 percent of the authorized amount (transmission hours) of SURTASS LFA sonar for training and testing within 10 nautical miles (nmi) (18.5 kilometers (km)) of any single OBIA during any year (no more than 124 hours in years 1-4 and 148 hours in years 5-7) unless the following conditions are met: Should national security present a requirement to conduct more than 25 percent of authorized hours of SURTASS LFA sonar within 10 nmi (18.5 km) of any single OBIA during any year, naval units will obtain permission from the appropriate designated Command authority prior to commencement of the activity. The Navy will provide NMFS with notification as soon as is practicable and include the information (
e.g.,
sonar hours) in its annual activity reports submitted to NMFS.

• The Navy has agreed to evaluate the feasibility and appropriate methods to collect new data to supplement the data available on behavioral responses of marine mammals to SURTASS LFA sonar using newer methods and technologies. These types of scientific inquiries fit within the scope the Navy's Living Marine Resources (LMR) program. The LMR program weighs the various Navy research needs against each other through a needs and solicitation process. The Navy has submitted a needs statement to the LMR advisory committee to research future data collection that would supplement understanding of how SURTASS LFA sonar may affect marine resources, including mysticetes and beaked whales.

Description of the Specified Activities

Overview

The Navy's primary mission is to organize, train, and equip combat-ready naval forces capable of accomplishing American strategic objectives, deterring maritime aggression, and assuring freedom of navigation in ocean areas. This mission is mandated by Federal law in Section 8062 of Title 10 of the United States Code, which directs the Secretary of the Navy to ensure the readiness of the U.S. naval forces.

The Secretary of the Navy and the Chief of Navy Operations (CNO) have established that anti-submarine warfare (ASW) is a critical capability for achieving the Navy's mission, and it requires unfettered access to both the high seas and littoral environments to be prepared for all potential threats by maintaining ASW core competency. The Navy is challenged by the increased difficulty in locating undersea threats solely by using passive acoustic technologies due to the advancement and use of quieting technologies in diesel-electric and nuclear submarines. At the same time, as the distance at which submarine threats can be detected decreases due to quieting technologies, improvements in torpedo and missile design have extended the effective range of these weapons.

One of the ways the Navy has addressed the changing requirements for ASW readiness was to develop SURTASS LFA sonar, which is able to reliably detect quieter and harder-to-find submarines at long range before these vessels can get within their effective weapons range to launch against their targets. SURTASS LFA sonar systems have a passive component (SURTASS), which is a towed line array of hydrophones used to detect sound emitted or reflected from submerged targets, and an active component (LFA), which is comprised of a set of acoustic transmitting elements. The active component detects objects by creating a sound pulse, or “ping” that is transmitted through the water and reflects off the target, returning in the form of an echo similar to echolocation used by some marine mammals to locate prey and navigate. SURTASS LFA sonar systems are long-range sensors that operate in the low-frequency (LF) band (
i.e.,
100-500 Hertz (Hz)). Because LF sound travels in seawater for greater distances than higher frequency sound, the SURTASS LFA sonar system meets the need for improved detection and tracking of new-generation submarines at a longer range and maximizes the opportunity for U.S. armed forces to safely react to, and defend against, potential submarine threats while remaining a safe distance beyond a submarine's effective weapons range. Thus, the active acoustic component in the SURTASS LFA sonar is an important augmentation to the Navy's passive and tactical systems, as its long-range detection capabilities can effectively counter the threat to the Navy and national security interests posed by quiet, diesel submarines.

The Navy's specified activities for MMPA incidental take coverage is to continue employment of SURTASS LFA sonar systems onboard USNS surveillance ships for training and testing activities conducted under the authority of the Secretary of the Navy in the western and central Pacific Ocean and eastern Indian Ocean, which is classified as a military readiness activity, beginning August 13, 2019. The use of the SURTASS LFA sonar system will result in acoustic stimuli from the generation of sound or pressure waves in the water at or above levels that NMFS has determined would result in take of marine mammals under the MMPA. This is the principal means of marine mammal taking associated with these military readiness activities. In addition to the use of active acoustic sources, the Navy's activities include the movement of vessels. This final rule also analyzes the potential effects of this aspect of the activities. NMFS does not anticipate takes of marine mammals to result from ship strikes from any SURTASS LFA vessels because each vessel moves at a relatively slow speed (10 to 12 knots (kt) while transiting), especially when towing the SURTASS and LFA sonar systems (moving at 3 to 4 kt), and for a relatively short period of time. Combined with the use of mitigation measures as noted below, it is likely that surveillance vessels will be able to avoid any marine mammals.

The Navy will restrict SURTASS LFA sonar training and testing activities to the central and western North Pacific Ocean and eastern Indian Ocean. The Navy will not conduct training or testing utilizing SURTASS LFA sonar within the foreign territorial seas of other nations and will maintain

SURTASS LFA sonar received levels below 180 decibels (dB) re: 1 μPa (root-mean-square (rms)) within 12 nmi (22 km) of any emerged land features or within 1 km of the seaward boundaries of designated Offshore Biologically Important Areas (OBIAs) during their effective periods (see
Mitigation
section below for OBIA details). In addition to these geographic mitigation measures, the Navy will implement procedural mitigation measures, including monitoring for the presence of marine mammals (including visual as well as active and passive acoustic monitoring) and implementing shutdown procedures for marine mammals within a mitigation zone around the LFA sonar source (see
Mitigation
and
Monitoring
sections below for further details).

Dates and Duration

The specified activities may occur at any time during the seven-year period of validity of the regulations (August 13, 2019, through August 12, 2026). The Navy currently conducts SURTASS LFA sonar activities from four vessels. The Navy is planning to add new vessels to its ocean surveillance fleet. As new vessels are developed, the onboard LFA and High Frequency Marine Mammal Monitoring sonar (HF/M3 sonar) systems (discussed below) may need to be updated, modified, or even re-designed. Current indications are that future LFA sonar systems will have the same operational characteristics and that updates and modifications are focused toward miniaturizing the system components to reduce the weight and handling of the systems. If system parameters are modified as a result of these updates the Navy will determine if supplementary analysis would be required to cover the deployment of these new systems. As the new vessels and sonar system components are developed and constructed, at-sea testing would eventually be necessary. The Navy anticipates that new vessels, or new/updated sonar system components, would be ready for at-sea testing beginning in the fifth year of the time period covered by this final rule.

Thus, the Navy's activity analysis included consideration of the sonar hours associated with future testing of new or updated LFA sonar system components and new ocean surveillance vessels. This consideration resulted in two scenarios of annual sonar transmit hours: Years 1 to 4 will entail up to 496 hours total per year across all SURTASS LFA sonar vessels, while years 5 to 7 will include an increase in LFA sonar transmit hours up to 592 hours across all vessels.

The SURTASS LFA sonar transmission hours represent a distribution across six activities that include (with an approximate allocation of hours indicated):

• Contractor crew proficiency training (80 hours per year);

• Military crew (MILCREW) proficiency training (96 hours per year);

• Participation in or support of naval exercises (96 hours per year);

• Vessel and equipment maintenance (64 hours per year);

• Acoustic research testing (160 hours per year); and

• New SURTASS LFA sonar system testing (96 hours per year; will occur in years 5 to 7).

Each of these activities utilizes the SURTASS LFA sonar system within the operating profile described above; therefore, the number of hours designated for each activity represents an estimate for planning purposes.

As noted above, this rulemaking would result in the fourth such regulation for the Navy's SURTASS LFA sonar activities. The Navy is currently conducting the specified activities under an NDE that will expire on August 12, 2019. Therefore, the Navy requested MMPA rulemaking and an LOA for SURTASS LFA sonar training and testing activities effective beginning August 13, 2019, to take marine mammals incidental to the SURTASS LFA sonar activities for a seven year period.

SURTASS LFA Sonar Training and Testing Areas

The geographic area of the SURTASS LFA sonar activities covered by these regulations includes the western and central North Pacific Ocean and eastern Indian Ocean outside of the territorial seas of foreign nations (generally 12 nmi (22 km) from most foreign nations). Figure 1 depicts the areas of SURTASS LFA sonar activities. In areas within 12 nmi from any emergent land (coastal exclusion areas) and in areas identified as OBIAs, SURTASS LFA sonar training and testing would be conducted such that received levels of LFA sonar are below 180 dB re: 1 μPa rms sound pressure level (SPL). This restriction will be observed year-round for coastal standoff zones and during known periods of biological importance for OBIAs.

BILLING CODE 3510-22-P

ER13AU19.000

BILLING CODE 3510-22-C
For this rulemaking, the Navy scoped the geographic extent of its specified activities to better reflect the areas where the Navy anticipates conducting SURTASS LFA sonar training and testing activities now through 2026. Fifteen representative model areas (shown in Figure 1 and listed in Table 1), with nominal modeling sites in each region, provide geographic context for the SURTASS LFA sonar activities.

Table 1—Representative SURTASS LFA Sonar Modeling Areas That the Navy Modeled for the 2019 SURTASS LFA FSEIS/SOEIS and the Navy's MMPA Rulemaking/LOA Application

Modeled site
Location (latitude/longitude of center of modeling area)
Notes

East of Japan
38° N, 148° E

North Philippine Sea
29° N, 136° E

West Philippine Sea
22° N, 124° E

Offshore Guam
11° N, 145° E
Navy Mariana Islands Testing and Training Area.

Sea of Japan
39° N, 132° E

East China Sea
26° N, 125° E

South China Sea
14° N, 114° E

Offshore Japan 25° to 40° N
30° N, 165° E

Offshore Japan 10° to 25° N
15° N, 165° E

Hawaii North
25° N, 158° W
Navy Hawaii-Southern California Training and Testing Area.

Hawaii South
19.5° N, 158.5° W
Navy Hawaii-Southern California Training and Testing Area.

Offshore Sri Lanka
5° N, 85° E

Andaman Sea
7.5° N, 96° E

Northwest of Australia
18° S, 110° E

Northeast of Japan
52° N, 163° E

Detailed Description of the Specified Activities

SURTASS LFA Sonar—
SONAR is an acronym for Sound Navigation and Ranging, and its definition includes any system (biological or mechanical) that uses underwater sound, or acoustics, for detection, monitoring, and/or communications. Active sonar is the transmission of sound energy for the purpose of sensing the environment by interpreting features of received signals. Active sonar detects objects by creating a sound pulse, or “ping” that is transmitted through the water and reflects off the target, returning in the form of an echo. Passive sonar detects the transmission of sound waves created by an object.

As mentioned previously, the SURTASS LFA sonar system is a long-range, all-weather LF sonar (operating between 100 and 500 Hertz (Hz)) system that has both active and passive components. LFA, the active system component (which allows for the detection of an object that is not generating noise), is comprised of source elements (called projectors) suspended vertically on a cable beneath the surveillance vessel. The projectors produce an active sound pulse by converting electrical energy to mechanical energy by setting up vibrations or pressure disturbances within the water to produce a ping. The Navy uses LFA as an augmentation to the passive SURTASS operations when passive system performance is inadequate. SURTASS, the passive part of the system, uses hydrophones (
i.e.,
underwater microphones) to detect sound emitted or reflected from submerged targets, such as submarines. The SURTASS hydrophones are mounted on a horizontal line array that is towed behind the surveillance vessel. The Navy processes and evaluates the returning signals or echoes, which are usually below background or ambient sound level, to identify and classify potential underwater targets.

LFA Active Component
—The active component of the SURTASS LFA sonar system consists of up to 18 projectors suspended beneath the surveillance vessel in a vertical line array. The SURTASS LFA sonar projectors transmit in the low-frequency band (between 100 and 500 Hz). The source level of an individual projector in the SURTASS LFA sonar array is approximately 215 dB re: 1 μPa at 1 m or less. Sound pressure is the sound force per unit area and is usually measured in micropascals (μPa), where one Pascal (Pa) is the pressure resulting from a force of one newton exerted over an area of one square meter (m
2
). The commonly used reference pressure level in underwater acoustics is 1 μPa at 1 m, and the units for source level are decibels (dB) re: 1 μPa at 1 m). Because of the physics involved in acoustic beamforming (
i.e.,
a method of mapping noise sources by differentiating sound levels based upon the direction from which they originate) and sound transmission loss processes, the SURTASS LFA sonar array cannot have a sound pressure level (SPL) higher than the SPL of an individual projector.

The SURTASS LFA sonar acoustic transmission is an omnidirectional beam (a full 360 degrees (°)) in the horizontal plane. The LFA sonar system also has a narrow vertical beam that the vessel's crew can steer above or below the horizontal plane. The typical SURTASS LFA sonar signal is not a constant tone, but rather is a transmission of various signal types that vary in frequency and duration (including continuous wave (CW) and frequency-modulated (FM) signals). A complete sequence of sound transmissions, also referred to by the Navy as a “ping” or a wavetrain, can be as short as six seconds (sec) or last as long as 100 sec, with an average length of 60 sec. Within each ping, the duration of any continuous frequency sound transmission is no longer than 10 seconds and the time between pings is typically from six to 15 minutes (min). Based on the Navy's historical operating parameters, the average duty cycle (
i.e.,
the ratio of sound “on” time to total time) for LFA sonar is normally 7.5 to 10 percent and will not exceed a maximum duty cycle of 20 percent.

Compact LFA Active Component
—In addition to the LFA sonar system currently deployed on the USNS IMPECCABLE, the Navy developed a compact LFA (CLFA) sonar system, which is now deployed on its three smaller surveillance vessels (
i.e.,
the USNS ABLE, EFFECTIVE, and VICTORIOUS). The operational characteristics of the active component for the CLFA sonar system are comparable to the LFA sonar system and the potential impacts from the CLFA sonar system will be similar to the effects from the LFA sonar system. The CLFA sonar system consists of smaller projectors that weigh 142,000 lbs (64,410 kilograms (kg)), which is 182,000 lbs (82,554 kg) less than the weight of the LFA projectors on the USNS IMPECCABLE. The CLFA sonar system also consists of up to 18 projectors suspended beneath the surveillance vessel in a vertical line array, and the CLFA sonar system projectors transmit in the low-frequency band (also between 100 and 500 Hz) with the same duty cycle as described for LFA sonar. Similar to the active component of the LFA sonar system, the source level of an individual projector in the CLFA sonar array is approximately 215 dB re: 1 μPa or less.

For the analysis in this rulemaking, NMFS will use the term LFA to refer to both the LFA sonar system and/or the CLFA sonar system, unless otherwise specified.

SURTASS Passive Component
—The passive component of the SURTASS LFA sonar system consists of a SURTASS Twin-line (TL-29A) horizontal line array mounted with hydrophones. The Y-shaped array is 1,000 ft (305 m) in length and has an operational depth of 500 to 1,500 ft (152.4 to 457.2 m).

High-Frequency Marine Mammal Monitoring Active Sonar (HF/M3)
—Although technically not part of the SURTASS LFA sonar system, the Navy will also use a high-frequency sonar system, called the HF/M3 sonar, to detect and locate marine mammals within the SURTASS LFA sonar mitigation zone, as described in the
Mitigation
and
Monitoring
sections. This enhanced commercial fish-finding sonar, mounted at the top of the SURTASS LFA sonar vertical line array, has a source level of 220 dB re: 1 μPa at 1 m with a frequency range of 30 to 40 kilohertz (kHz). The duty cycle is variable, but is normally below three to four percent and the maximum pulse duration is 40 milliseconds (ms). The HF/M3 sonar has four transducers with 8 degrees horizontal and 10 degrees vertical beamwidths, which sweep a full 360 degrees in the horizontal plane every 45 to 60 sec with a maximum range of approximately 1.2 mi (2 km).

Vessel Specifications
—The Navy currently deploys SURTASS LFA sonar on four twin-hulled ocean surveillance vessels that are 235 to 282 feet (ft) (72 to 86 m) in length, with twin-shafted diesel electric engines capable of providing 3,200 to 5,000 horsepower. Each vessel has an observation area on the bridge that is more than 30 ft above sea level from where lookouts will monitor for marine mammals whenever SURTASS LFA sonar is transmitting. As stated previously, the Navy may develop and field additional SURTASS LFA equipped vessels, either to replace or complement the Navy's current SURTASS LFA capable fleet, and these vessels may be in use beginning in the fifth year of the time period covered by this rulemaking.

The operational speed of each vessel during sonar activities will be approximately 3.4 miles per hour (mph)

(5.6 km per hour (km/hr); 3 kt) and each vessel's cruising speed outside of sonar activities would be a maximum of approximately 11.5 to 14.9 mph (18.5 to 24.1 km/hr; 10 to 13 kt). During sonar activities, the SURTASS LFA sonar vessels will generally travel in straight lines or in oval-shaped (
i.e.,
racetrack) patterns depending on the training or testing scenario.

Comments and Responses

We published a notice of proposed rule in the
Federal Register
on March 1, 2019 (84 FR 7186), with a 30-day comment period. During the 30-day comment period, we received eight total comment letters. Of this total, one submission was from another Federal agency, one letter was from organizations or individuals acting in an official capacity (
e.g.,
non-governmental organizations (NGOs)), and six submissions were from private citizens. NMFS has reviewed all public comments received on the proposed rule and issuance of the LOA. All relevant comments and our responses are described below organized by major category. We provide no response to specific comments that addressed species or statutes not relevant to our proposed rule under section 101(a)(5)(A) of the MMPA (
e.g.,
comments related to sea turtles).

General Comments

The majority of the comments from six private citizens expressed general opposition toward the Navy's proposed training and testing activities, cited concern for marine mammals and the oceans, and requested that NMFS not issue the LOAs, but without providing information relevant to NMFS' decisions. NMFS appreciates the concerns expressed for marine life and resources. We reiterate that no mortality of marine mammals is anticipated, nor is any injury (Level A harassment) of marine mammals anticipated; therefore, neither injuries nor mortality of marine mammals is authorized for the SURTASS LFA sonar activities. Moreover, the MMPA directs the Secretary of Commerce (whose authority has been delegated to NMFS) to allow, upon request, the incidental taking for a specified activity, provided that we are able to make the required findings under section 101(a)(5)(A) and set forth regulations containing the required prescriptions for mitigation, monitoring, and reporting after notice and comment. Therefore, these comments were not considered further. The remaining comments are addressed below.

Impact Analysis

Density Estimates

Comment 1:
The Marine Mammal Commission (hereafter “Commission”) expressed concerns regarding the density estimates used in Navy's Global Marine Species Density Database (Global NMSDD). The Commission and The Commission and Natural Resources Defense Council (NRDC), The Humane Society of the United States, and Humane Society Legislative Fund (hereafter “NRDC
et al.”
) recommended that NMFS require the Navy to make available to the public the resulting products of the current version of the Global NMSDD, similar to the information provided in Department of the Navy (2017c), as soon as possible. The Commission noted that they have requested for several years that this information be made available to the public and are puzzled why neither the Navy nor NMFS has provided it. The Commission asserted that without public access to such data, the process is not transparent and there is no basis to assert that either NMFS' or the Navy's analyses are based on best available data.

Response:
Currently, the NMSDD is not publically available since proprietary geospatial modeling data are included in the database, for which the Navy has established proprietary data sharing agreements. However, products of the Navy's database have been made available to the public, such as the
U.S. Navy Marine Species Density Database Phase III for the Hawaii-Southern California Training and Testing Study Area
(DoN, 2017c). The citations for the sighting surveys or other data upon which the densities were derived in the NMSDD have been provided when appropriate, and information similar to that presented in the
U.S. Navy Marine Species Density Database Phase III for the Hawaii-Southern California Training and Testing Study Area
(DoN, 2017c) is provided in the 2019 SURTASS LFA FSEIS/SOEIS (Chapter 3 and Appendix D) for the 15 Representative Modeling Areas in the SURTASS LFA sonar Study Area. Chapter 3, Section 3.4.3.3.3 describes the process and methods used to derive marine mammal occurrence and population estimates (abundance and density) in the model areas. Appendix D includes detailed information on the available data and abundance and density estimates by model area and species/stock and these references are also included in the marine mammal species, stocks (DPSs), abundance, and density estimates by season summary table (Chapter 3, Table 3-8). When the NMSDD is referenced in the Offshore Sri Lanka, Andaman Sea, Northwestern Australia, and Northeast of Japan (humpback whales only) modeling areas the specific data source (
e.g.,
Kaschner
et al.,
2006 or SMRU Ltd., 2012) is also referenced. NMFS coordinated closely with the Navy in the development of its incidental take application, and agrees that the methods the Navy has put forth described herein to estimate densities are appropriate and based on the best available science.

Comment 2:
The Commission and NRDC et al. recommended that NMFS specify whether and how uncertainty was incorporated in abundance and density estimates in the preamble to the final rule and, if it was not, that NMFS require the Navy to incorporate measures of uncertainty inherent in the underlying data (
e.g.,
CV, standard deviations, standard errors) in those estimates and re-estimate the numbers of takes accordingly in the final rule. The Commission noted that for all of the Navy's Phase III activities since 2016, including for Hawaii-Southern California Training and Testing (HSTT), the Navy has incorporated uncertainty in the densities and the group size estimates that ultimately seed its animat modeling. It is unclear why the same approach was not taken for SURTASS LFA sonar, particularly since the action areas for HSTT and SURTASS LFA sonar overlap.

Response:
Information on uncertainty (
e.g.,
CV, standard deviations, standard errors, etc.) in species/stock population estimates for each modeling area is included when available in the 2019 SURTASS LFA FSEIS/SOEIS (Chapter 3 and Appendix D). The population estimates provided in the 2019 SURTASS LFA FSEIS/SOEIS (Chapter 3 and Appendix D) were used to model estimated takes using the Acoustic Integration Model (AIM) (described in the
Estimated Take of Marine Mammals
section). The AIM is a Monte Carlo based statistical model in which multiple iterations of realistic predictions of acoustic source use as well as animal distribution and movement patterns (“animats”) are conducted to provide statistical predictions of estimated impacts from exposure to acoustic source transmissions. AIM does not include uncertainty in population estimates to predict estimated takes, however uncertainty in the horizontal and vertical movement patterns of marine mammals is incorporated through the Monte Carlo components of the AIM. At each 30-sec timestep, the diving pattern, swim speed, and heading of each animat are re-sampled, resulting in movement of each animat through the acoustic

field. In the AIM, the modeled marine mammal animats were set to populate the simulation area with densities of 0.086, 0.17, or 0.34 animats/nmi
2
(0.025, 0.05, or 0.1 animats/km
2
). These densities are often higher than those estimated in the marine environment (as many species/stocks are rare in modelled areas). This “over population” of the modeling environment ensures that the result of the simulation is not unduly influenced by the chance placement of a few simulated marine mammals. To obtain final harassment estimates, the modeled results are normalized by the ratio of the modeled animat density to the real-world marine mammal density estimate. This allows for greater statistical power without overestimating risk. Additional details on the methods used to calculate take estimates are included in the
Estimated Take of Marine Mammals
section. NMFS considers these estimates conservative as take estimates are based on the maximum potential impact to a species or stock across all model areas in which a SURTASS LFA sonar activity may occur. Therefore, if an activity occurs in a different model area than the area where the maximum potential impact was predicted, the actual potential impact may be less than estimated. Here, the densities and modeling used reflect the best available science and, further, monitoring of SURTASS activities from the past 17 years of activities do not suggest that these models have underestimated marine mammal exposure.

Comment 3:
NRDC et al. recommended that NMFS consider alternative and potentially more powerful modeling approaches that are emerging to extrapolate cetacean densities beyond surveyed regions (Corkeron et al., 2011; Lambert et al., 2014; Mannocci et al., 2015) which are likely to be superior to the Kaschner et al. (2006) model (and more consistent with the prior recommendations of NMFS biologists) that the Navy has relied on in the past. They recommended that the Navy should consult with NMFS experts on the utility of these models for estimating densities within the LFA Study Area. They also recommended that NMFS examine the data collected during the International Whaling Commission's Pacific Ocean Whale and Ecosystem Research Programme (IWC-POWER) 2010, 2013, 2014, 2015, and 2016 surveys with the view to developing improved marine mammal density models for regions of the western and central Pacific.

Response:
NMFS is aware of the active area of research in developing density models for data poor areas that extrapolate cetacean densities beyond surveyed regions. For example, the Navy and NMFS were reviewers of, and used, the results of Mannocci
et al.
(2017) in the U.S. Navy's Atlantic Fleet Training and Testing (AFTT) Study Area NEPA analysis and MMPA rulemaking. NMFS and the Navy will continue to discuss and examine the utility of these emerging models for estimating densities of marine mammals in the SURTASS LFA sonar Study Area. It is possible that the sighting results from the IWC-POWER cruises could be used to extrapolate density and abundance estimates throughout the North Pacific in the future, using the methods developed by Mannocci et al. (2015) that were applied to extrapolate density estimates in the North Atlantic (Mannocci et al., 2017). Cruise reports through 2017 are available online, with cruises continuing for another few years. When additional results are available, NMFS and the Navy will consider use of these methods to extrapolate density and abundance estimates that could inform mitigation through Adaptive Management process, or to inform analyses for future actions. Lambert et al. (2014) used the simulated distribution of micronekton from the Spatial Ecosystem And Population Dynamics Model (SEAPODYM) to predict the habitat of three cetacean guilds in tropical waters. While their results provide some interesting insights into the use of predicted prey maps in cetacean distribution models, they are best used to prioritize future research areas. Corkeron et al. (2011) developed statistical methods for using spatially autocorrelated sighting results to identify the Dhofar coast of Oman as an important region for the Arabian Sea DPS of humpback whales. However, the Dhofar coast of Oman is outside of the SURTASS LFA sonar Study Area and Corkeren et al. state “Although it is theoretically possible for us to project model predictions into other areas, we consider this inadvisable, as our basic design was not to make inference about the distribution of humpback whales along the entire Oman coast.” Therefore, though its statistical models could be applied to sightings data within the SURTASS LFA Study Area, these humpback whale results are not applicable. When considering how to predict marine mammal densities across large spatial scales using many varied datasets, there are often multiple appropriate and effective ways that data can be modeled and extrapolated, and NMFS does not prescribe any particular model in these cases, as long as our review indicates that the proposed method is supportable. Here, the densities and modeling used reflect the best available science and, further, monitoring of SURTASS activities from the past 17 years of activities do not suggest that these models have underestimated marine mammal exposure.

Comment 4:
The Commission recommended that, in the preamble to the final rule, NMFS specify how density estimates were derived and what statistic (
e.g.,
mean, median, maximum) was used when multiple sources are referenced in Tables 2-16 of the
Federal Register
notice and Table 3-2 of the revised LOA application.

Response:
We have included the density estimate and associated reference or references for each species/stock in each of the 15 Representative Modeling Areas in the SURTASS LFA sonar Study Area in Tables 2 through 16 of this rule. Additional details on the densities used for each species/stock in each modeling area are provided in the 2019 SURTASS LFA FSEIS/SOEIS (Chapter 3, Table 3-8 and Appendix D). In Chapter 3, Table 3-8 2019 SURTASS LFA FSEIS/SOEIS, multiple references are provided to reflect references used to support the population density estimate and seasonality of occurrence. In Tables 2-16 of this rule we have included only the reference to the density estimate. Appendix D of the 2019 SURTASS LFA FSEIS/SOEIS includes detailed descriptions and references for each species/stock in each of the model areas that include how each density estimate was derived. In response to this comment the Navy has also reviewed and revised the descriptions in Appendix D of the 2019 SURTASS LFA FSEIS/SOEIS to increase clarity.

Comment 5:
With respect to estimated densities of cetaceans in Offshore Guam, the Commission recommended that NMFS use the densities stipulated in Department of the Navy (2018b) for blue whales, Bryde's whales, fin whales, ginkgo-toothed beaked whales, and Deraniyagala's beaked whales rather than the densities in Table 5 of the
Federal Register
notice and re-estimate the numbers of takes accordingly in the final rule.

Response:
As recommended, we have revised the densities for blue whales, Bryde's whales, fin whales, ginkgo-toothed beaked whales, and Deraniyagala's beaked whales to those presented in the
U.S. Navy marine species density database Phase III for the Mariana Islands Training and Testing Study Area
(DoN, 2018b) and have revised our estimated takes of

these species/stocks in the Offshore Guam modeling area accordingly.

Comment 6:
NRDC et al. recommended that NMFS require the Navy to conduct baseline research in unsurveyed areas that it repeatedly employs in LFA sonar operations, prioritizing areas on the basis of exposure frequency, environmental vulnerability, and research feasibility.

Response:
Per the Council on Environmental Quality (CEQ) regulation 40 CFR 1502.22, the Navy has indicated plainly in the 2019 SURTASS LFA FSEIS/SOEIS where data or information are lacking to support Navy analyses and how the Navy has resolved the issue of scarcity of data/information (
i.e.,
surrogate data/information). The Navy is not required to conduct costly baseline research, such as that suggested, to obtain incomplete or unavailable data and information for areas in which the Navy operates LFA sonar (CEQ Regulation 1502.22). Further, the ESA and MMPA only require that a Federal agency consider the best available data, and do not require the agency generate the data itself. However, as noted in this rule, the Navy does fund ongoing research and conservation related to marine mammals. The Navy sponsors a significant portion of the U.S. research on the effects of human-generated sound on marine mammals (between approximately 25 to 30 million dollars per year on marine mammal research from the Navy's three main programs: Office of Naval Research, Living Marine Resources Program, and the Fleet/SYSCOM monitoring programs), which is crucial to the overall knowledge base on the potential for effects from underwater anthropogenic noise on marine mammals (82 FR 19460, 19516; April 27, 2017). See Office of Naval Research (
https://www.onr.navy.mil/
) and Navy Living Marine Resources program (
https://navysustainability.dodlive.mil/environment/lmr/
) for examples of Navy support research. The Navy also sponsors research to determine marine mammal abundances and densities for all Navy ranges and other operational areas (see Marine Species Monitoring Program:
https://www.navymarinespeciesmonitoring.us/
). As described in the
Description of Marine Mammals in the Area of the Specified Activities
section of the rule and Chapter 3 and Appendix D of the SURTASS LFA FSEIS/SOEIS, the Navy used a combination of density estimates from a region with similar oceanographic characteristics to that model area, estimates derived from the Navy's Marine Species Density Database (DoN, 2018), and pooled density estimates for species of the same genus if sufficient data were not available to compute a density for individual species or the species are difficult to distinguish at sea (
e.g., Mesoplodon
spp. and
Kogia
spp.) to inform their analyses in unsurveyed areas, which NMFS concurred represented the best available science.

Permanent Threshold Shift (PTS)/Temporary Threshold Shift (TTS) Thresholds and Take Estimates

Comment 7:
The Commission recommended that NMFS (1) specify the numbers of model-estimated Level A harassment (PTS) takes of marine mammals in the absence of implementing mitigation measures and any and all assumptions (including within the animat modeling scenarios) that were made to reduce those takes to zero in the preamble to the final rule and (2) authorize the model-estimated Level A harassment (PTS) takes rather than reducing them to zero in the final rule. The Commission stated that specifics regarding the situations in which those takes were estimated to occur (
i.e.,
distances to the source and timeframe over which the exposure occurred) should be delineated in the preamble to the final rule as well.

Response:
The Navy quantitatively assessed the potential for PTS and TTS resulting from exposure to SURTASS LFA sonar transmissions using NMFS' 2018 Acoustic Technical Guidance for estimating impacts of PTS and TTS using AIM. In AIM the potential for PTS is considered within the context of the mitigation and monitoring efforts that would occur whenever SURTASS LFA sonar is transmitting. Mitigation monitoring is designed to detect marine mammals before they are exposed to a received level of 180 dB re: 1 μPa SPL. The probability of detection of a marine mammal by the HF/M3 system alone within the LFA sonar mitigation zone approaches 100 percent over the course of multiple pings (see the 2001 SURTASS LFA FOEIS/EIS, Subchapters 2.3.2.2 and 4.2.7.1 for the HF/M3 sonar testing results as well as section 5.4.3 of the 2019 SURTASS LFA FSEIS/SOEIS for a summary of the effectiveness of the HF/M3 system). As described in the
Estimated Take of Marine Mammals
section, with the implementation of the three-part monitoring programs (visual, passive acoustic, and HF/M3 monitoring, as discussed below), NMFS and the Navy do not expect that marine mammals would be injured by SURTASS LFA sonar because a marine mammal is likely to be detected and active transmissions suspended or delayed to avoid injurious exposure. Therefore, in incorporating mitigation, AIM assumes no animats will be exposed to SURTASS LFA sonar in the LFA sonar mitigation zone. AIM records the exposure history for each individual animat and the potential impact is determined on an individual animal basis. The sound energy received by each individual animat over the 24-hr modeled period was calculated as sound exposure level (SEL) and the potential for that animal to experience PTS and then TTS was considered using the NMFS (2018) acoustic guidance thresholds. When mitigation is applied in the modeling-analysis environment, estimations of PTS impacts were 0 for all marine mammal species in all model areas.

Therefore, the Navy did not request and NMFS is not authorizing Level A harassment take. As presented in the
Estimated Take of Marine Mammals
section, based on simple spherical spreading (
i.e.,
transmission loss based on 20 × log10 [range {m}]), all hearing groups except LF cetaceans would need to remain within 22 ft (7 m) for the entire duration (60 sec) of an LFA sonar ping to potentially experience PTS. LF cetaceans would need to remain at the greatest distance from the transmitting LFA sonar, 135 ft (41 m) before experiencing the onset of PTS. This distance is well within the LFA sonar mitigation zone and a distance where visual, passive, and acoustic monitoring can reliably detect small and large marine mammals 100 percent of the time and transmission can shut down before any injury can occur. NMFS has determined that the suite of mitigation monitoring efforts is highly effective at detecting marine mammals and avoiding Level A take and notes that there have been no reported or known incidents of Level A harassment of any marine mammal in 17 years of SURTASS LFA sonar activities. Therefore, NMFS has determined that authorizing Level A harassment take is not warranted.

Comment 8:
The Commission recommended that NMFS explain why TTS takes are greater than behavior takes for some species of mysticetes, or stocks of mysticetes within the same species, in the preamble to the final rule.

Response:
The estimated Level B harassment takes presented in Chapter 4 of the 2019 SURTASS LFA FSEIS/SOEIS are correct. Table 18 in this final rule presents total Level B Harassment takes (including both behavioral disruption and TTS). In the vast majority of mysticete species/stocks, estimated takes by behavioral disruption

are greater than estimated incidents of TTS; however, in a few cases the predicted numbers of TTS are higher than the estimated takes by behavioral disruption. This is due to the way these two impacts are assessed. The TTS acoustic threshold level is based on cumulative SEL metric and a take occurs when a marine mammal exposed to sounds above the threshold level (a step function where 0 is no take and 1 is a take for each individual). Behavioral response is calculated for each individual on a continuum from 0 to 1 based on the marine mammals single ping equivalent (SPE) value. Therefore, many more marine mammals may be (and typically are) exposed at sound (SPE) levels with a very low risk for a behavior response (less than 1). When these risk values are summed to calculate the estimated take due to behavioral response, the result may be an estimate that is lower than the estimate for TTS. In their response to comments in the SURTASS LFA FSEIS/SOEIS, the Navy provides the following example to illustrate: If the blue whale has a hypothetical population estimate of 10 individuals, one animal may experience TTS, five may have some percent risk of a behavioral response, and four may not be impacted. Estimating take, one animal is predicted to experience TTS. The five animals in the population have potential behavioral response (risk values) of 0.5, 0.2, 0.05, 0.04, and 0.01. When summed, this is 0.8 for the entire population. Therefore, the risk of TTS (1 animal) is greater than the risk of behavioral response (0.8 animal), but the number of animals experiencing TTS (one) is less than the number that have the potential to experience a behavioral response (five).

Behavioral Harassment Thresholds and Take Estimates

Comment 9:
With respect to SPE as the metric to estimate behavioral response, the Commission recommended that NMFS use either (1) a metric (
i.e.,
SPL or sound exposure level (SEL)) and associated thresholds that are based on physics rather than SPE or (2) the behavioral response metrics and thresholds that the Navy currently uses for all other LF sonar sources based on Department of the Navy (2017b) to estimate behavior takes for the final rule. NRDC et al. also stated that given the lack of any tenable justification for maintaining an SPE approach, NMFS, and the Navy, should use the more widely accepted, more conservative SEL in determining the effect of multiple exposures on marine mammals.

Response:
The behavioral risk function is based on field measurements of behavioral responses of mysticetes during the SURTASS LFA Sonar Low Frequency Sound Scientific Research Program (LFS SRP). SPE was developed by researchers in the LFS SRP to account for received energy from all LFA sonar transmissions that a modeled animal (“animat”) receives during a 24-hr period of a SURTASS LFA sonar mission. SPE was also designed to approximate the manner in which the effect of repeated exposures accumulate, as known from studies on humans (Kryter, 1985; Richardson
et al.,
1995; Ward, 1968). SPE accounts for the increased potential effect of repeated exposures on animals by adding 5 x log10 (number of pings) to each 1-dB received level (RL) increment (Kryter, 1985; Richardson et al., 1995; Ward, 1968). If an individual's exposure within a 24-hour period is dominated by a single loud pulse, the SPE will not be greater than the SPL (rms) of that single loud pulse. However, if there are two or more pulses of the same amplitude, the calculated SPE will be greater than the SPL (rms) of a single pulse because the SPE metric accounts for accumulation, and SPL does not. Therefore, the calculated SPE is never lower than the SPL rms of the loudest pulse.

The SEL metric is used to determine physiological effects (PTS and TTS) and the Navy's rulemaking and LOA application, as well as this final rule, use the SEL metric to estimate these impacts as described in the NMFS' 2018 Acoustic Technical Guidance. Research indicates that behavioral responses are context specific and due to both received level and a suite of other factors including behavioral context. All other applicants use SPL thresholds for assessing Level B harassment by behavioral disruption, and the Navy uses SPL based risk functions for all of its other training and testing activities, which utilize sound sources of shorter pulse lengths. Since SPE allows for a consideration of the duration of a signal and is always more conservative than SPL rms values, it is equal to or more conservative than an SPL based risk function and NMFS concurs with its use with SURTASS LFA sonar.

Although the LFS SRP study is from the late 1990s, the source used was the most similar in source characteristics and operating parameters to the SURTASS LFA sonar source, and most closely matches the nature and context of the Navy's current activity. Specifically, the multiple LF sources that may be used in the Navy's major training exercises (such as AFTT and HSTT) include sources that are operated differently, are operated at different frequencies, and are only one component of any training activity — and for these reasons, the Navy and NMFS found it appropriate to apply the thresholds and modeling utilized for the other active Navy sources. However, for SURTASS, the results of the LFS SRP remain the best available data for the purpose of predicting potential impacts from exposure to SURTASS LFA sonar as they evaluated the behavioral responses of LF hearing specialists conducting biologically important behaviors to exposures of SURTASS LFA sonar. NMFS and the Navy have evaluated the science conducted with other sound sources (
e.g.,
mid-frequency sonar, the European “low-frequency active sonar” that operates at 1-2 and 6-7 kHz) and no newer data change the prediction of expected behavioral responses.

Comment 10:
The Commission recommended that NMFS and the Navy prioritize conducting a behavioral response study (BRS) using updated BRS methods involving SURTASS LFA sonar and mysticetes, other odontocetes including sperm whales, and/or phocids under the monitoring requirements for the final rule and ensure that the behavior thresholds are able to be updated accordingly before the next rulemaking.

Response:
The Navy has agreed to evaluate the feasibility and appropriate methods to collect new data to supplement the data available on behavioral responses of marine mammals to SURTASS LFA sonar using newer methods and technologies. These types of scientific inquiries fit within the scope the Navy's Living Marine Resources (LMR) program. The LMR program weighs the various Navy research needs against each other through a needs and solicitation process. The Navy has submitted a needs statement to the LMR advisory committee to research future data collection that would supplement understanding of how SURTASS LFA sonar may affect marine resources, including mysticetes and beaked whales.

Comment 11:
NRDC et al. noted that the proposed rule analysis relies entirely on the LFA Scientific Research Program (SRP) in establishing behavioral risk parameters for the SURTASS LFA system. They noted that study took place twenty years ago and is inconsistent with more recent science on the behavioral response of marine mammals to low-frequency underwater noise. They stated that reliance on the SRP to the exclusion of all other scientific literature on the impacts of

low-frequency sound would be arbitrary and capricious. NRDC et al. noted that marine mammal science, including the technology used to study behavioral response to underwater noise, has advanced significantly over the two decades since the SRP concluded. They stated that the tags used in the SRP were Time-Depth Recorders, which, in rendering only depth profile, are primitive by comparison with contemporary marine mammal tags, which include accelerometers, magnetometers, and hydrophones. The newer tags provide far greater capacity to track alterations in animal orientation, velocity, and noise production, and therefore to detect disruptions in marine mammal feeding and other behaviors. Additionally, they noted that the SRP's sample sizes were small, focal species were limited, and the LFA system was generally operated at less than full power. They noted that new technologies and methods indicate limitations of the Navy's research. They cited studies that observed reductions in buzz rates in sperm whales and harbor porpoises that could not have been observed without newly available technology (Miller et al., 2009; Pirotta et al., 2014).

Response:
As noted in the response to Comment 9, the data collected during the SURTASS LFA sonar LFS SRP studies remain the best available data for predicting behavioral responses to SURTASS LFA sonar. However, NMFS and Navy also considered other relevant studies on the potential effects of LF sound transmissions on marine mammals. None of these other studies contradict the conclusions of the LFS SRP (see the
Potential Effects of the Specified Activity on Marine Mammals and their Habitat
section in the proposed rule and Chapter 4 of the 2019 SURTASS LFA FSEIS/SOEIS for descriptions of studies). While we acknowledge the age of the SURTASS sonar LFS SRP data, the age of these data does not invalidate them, their contributions to science, nor the conclusions based upon those data. It is true that the technology and techniques available to gather marine animal data have become increasingly diverse and sophisticated over time and that LFS SRP sample sizes were small. The commenter points out the sorts of data that may be gathered utilizing new technologies and cites to the “limitations” of the SRP. NMFS acknowledges that newer methods may allow for additional data collection, however, in the meanwhile, NMFS and the Navy have considered all of the data, LFS SRP and otherwise, that are applicable to the SURTASS LFA sonar assessment and are aware of no basis to invalidate the overall results of the SRP. As noted in the response to Comment 10, the Navy will evaluate the feasibility and appropriate methods to collect new data to supplement the data available on behavioral responses of marine mammals to SURTASS LFA sonar.

Comment 12:
NRDC et al. noted that the Navy claims that the SRP remains more relevant than the host of more recent investigations because it is the only study of a tonal source operating at frequencies below 500 Hz. The commenters noted that researchers in the Stellwagen Bank National Marine Sanctuary documented suppression in humpback whale vocalization during operations of an Ocean Acoustic Waveguard Remote Sensing (OAWRS) system, a powerful low-frequency fish sensor operating at similar frequencies, at distances of 200 km from the source (Risch et al. 2012). The Heard Island Feasibility Test, which likewise involved a tonal sound source operating below 500 Hz, reported complete cessations in vocalizations of long-finned pilot whales and sperm whales over a 4900 km
2
area following exposure (Bowles et al. 1994). They stated that these papers join a spate of other studies documenting large-scale changes in baleen whale vocalizations and those of other species in response to predominantly low-frequency anthropogenic noise (Nowacek et al., 2015) and that the best available science indicates that the Navy's behavioral response function for LFA, promulgated by NMFS in the Proposed Rule, is non-conservative.

Response:
We disagree that the LFA sonar behavioral response function is non-conservative. Discussion of additional studies on the behavioral responses of marine mammals to a variety of sound sources are provided in the
Potential Effects of the Specified Activity on Marine Mammals and their Habitat
section in the proposed rule and Chapter 4 of the 2019 SURTASS LFA FSEIS/SOEIS. As discussed in the proposed rule, the potential for behavioral response to an anthropogenic source is highly variable and context-specific. Also, as discussed in the proposed rule, the recorded OAWRS produced a series of frequency-modulated pulses and signal received levels. Risch
et al.
(2012) documented reduction in humpback whale vocalization concurrent with transmissions of the low-frequency OAWRS system at distances of 200 km (108 nmi) from the source. The OAWRS source appears to have affected more whales than Phase III of the LFS SRP, even though exposure was at a lower RL (88 to 110 dB re: 1 μPa), which the authors noted was a novel sound source that provided a compelling contextual probability for the observed effects. Gong
et al.
(2014) assessed the effects of the OAWRS transmissions on calling rates on Georges Bank and determined constant vocalization rates of humpback whales, with a reduction occurring before the OAWRS system began transmitting. Risch
et al.
(2014) pointed out that the results of Risch
et al.
(2012) and Gong
et al.
(2014) are not contradictory, but rather highlight the principal point of their original paper that behavioral responses depend on many contextual factors, including range to source, RL above background noise level, novelty of signal, and differences in behavioral state. Further, the authors did not state or imply that the observed behaviors had long-term effects on individual animals or populations. The responses of whales to the OAWRS system are consistent with the LFA behavioral response function, as it estimates that behavioral changes can occur at received levels lower than 180 dB. Results from the Heard Island Feasibility Test (Bowles et al., 1994) show that during the pre-experiment baseline period, sperm whales were detected 24 percent of the time and short-finned pilot whales were detected eight percent of the time. During night-time recordings during the baseline period, sperm whales were detected eight percent of the time and pilot whales were detected zero percent of the time. Neither species was detected during the low-frequency transmissions, but both species were detected 36 h after transmissions ended. It is not known whether sperm and pilot whales were masked during the transmissions or whether they ceased vocalizing. Since sperm whales frequently become silent in the presence of anthropogenic noise (Watkins and Schevill, 1975; Watkins
et al.,
1985), it is possible they exhibited a behavioral response.

NMFS concurs with the use of the Navy's behavioral response function and that it conservatively estimates Level B harassment takes. There is no indication that this method underestimates take. While the entire ensonified area cannot be monitored (using visual or passive and active acoustic monitoring), marine mammal observations during SURTASS LFA sonar activity and those predicted using annual activity level and location indicate the Navy has never exceeded authorized take for SURTASS LFA sonar activities (with the first LOA for SURTASS LFA sonar activities

beginning in August 2002). The potential for behavioral response to an anthropogenic source is highly dependent on context, including characteristics of the sound signals and their pattern of transmission, the environmental factors affecting sound movement, and the behavioral state of the animal during exposure. Further, not every response of a marine mammal rises to the level of a take, and some of the responses cited by the commenter would not necessarily do so (
e.g.,
minor modifications in vocalizations of a duration shorter than exposure to the signal). As previously noted, the SURTASS LFS SRP exposed LF specialist cetaceans engaged in biologically important behaviors to real-world SURTASS LFA sonar transmissions; the SRP results remain the best available science for assessing potential impacts associated with exposure to SURTASS LFA sonar. The SURTASS LFS SRP experiments exposed baleen whales to RLs ranging from 120 to about 155 dB re: 1 µPa rms SPL and detected only minor, short-term behavioral responses. Short-term behavioral responses do not necessarily constitute significant changes in biologically important behaviors. The behavioral response function is also conservative for non-LF specialists, as it was developed for species believed to be most sensitive to SURTASS LFA sonar. Therefore, although the results of the risk function modeling are interpreted such that they would constitute “significant disruptions to biologically important behaviors,” (
i.e.,
causing disruption of natural behavioral patterns, including, but not limited to, migration, surfacing, nursing, breeding, feeding, or sheltering, to a point where such patterns are abandoned or significantly altered) not all predicted exposures would in fact rise to such a level, and the resulting risk function modeling is conservative for all marine mammals.

Mitigation and Monitoring

Least Practicable Adverse Impact Determination

Comment 13:
The Commission noted that NMFS' interpretation of the least practicable impact standard in various proposed rules has been an evolving one, and it is unclear that any of those discussions, targeted to specific instances, should be considered to constitute a formal interpretation. Rather, it is a shifting target that requires the Commission and other stakeholders to comment repeatedly on the various permutations. The Commission stated that such generally applicable policies and interpretations should be developed through a separate rulemaking (
e.g.,
in amendments to 50 CFR 216.103 or 216.105) or policy statement rather than in individual incidental take authorizations and recommended that NMFS pursue such a rulemaking or publish a proposed policy for public review and comment. The Commission expressed concerns that some stakeholders may not be aware of or choose not to comment on the proposed interpretation in this context, because the particular authorization may not otherwise be of interest to them (
e.g.,
because the activity is in a geographical location or concerns a type of activity not of particular interest).

Response:
We appreciate the Commission's recommendation and may consider the recommended approaches in the future. We note, however, that providing relevant explanations in a proposed incidental take rule is an effective and efficient way to provide information to the reader and solicit focused input from the public, and ultimately affords the same opportunities for public comment as a stand-alone rulemaking would. NMFS has provided similar explanations of the least practicable adverse impact standard in other recent section 101(a)(5)(A) rules, including: the final rules for U.S. Navy Training and Testing Activities in the Atlantic Fleet Study Area (83 FR 57076; November 14, 2018) and the Hawaii-Southern California Study Area (83 FR 66846; December 21, 2018), as well as the proposed rule for Geophysical Surveys Related to Oil and Gas Activities in the Gulf of Mexico (83 FR 29212; June 22, 2018).

Comment 14:
The Commission stated that in its previous letters it recommended that NMFS adopt a two-step approach when applying the least practicable adverse impact standard. First, it should identify the criteria it will use to determine whether adverse impacts on marine mammal species/stocks or their habitat are anticipated. If potential adverse impacts are identified, the second step should be to determine whether measures designed to reduce those impacts are available and practicable. The Commission expressed concern that, because NMFS' criteria for applying the least practicable adverse impact standard commingle elements related to whether impacts are adverse and whether potential mitigation measures are likely to be effective, NMFS' analysis is not as clear as it should be. The Commission therefore recommended that NMFS rework its evaluation criteria for applying the least practicable adverse impact standard to separate the factors used to determine whether a potential impact on marine mammals or their habitat is adverse and whether possible mitigation measures would be effective.

Response:
The Commission recommends NMFS consider applicable factors in its least practicable adverse impact analysis in a specific manner. However, it did not provide any suggested criteria for determining its recommended first step.

NMFS has clearly articulated the agency's interpretation of the LPAI standard and our evaluation framework in the
Mitigation
section of this notice. Specifically, NMFS identified the adverse impacts that it is considering in the LPAI analysis and comprehensively evaluated an extensive suite of measures that might be available to reduce those impacts (some of which are adopted and some that are not) both in the context of their expected ability to reduce impacts to marine mammal species or stocks and their habitat, as well as their practicability (see
Mitigation
and
Negligible Impact Analysis and Determination
sections). In the
Mitigation
section, NMFS has explained in detail our interpretation of the least practicable adverse impact standard, the rationale for our interpretation, and our approach for implementing our interpretation. The ability of a measure to reduce effects on marine mammals is entirely related to its “effectiveness” as a measure, whereas the effectiveness of a measure is not connected to its practicability. NMFS' interpretation of the LPAI standard is a reasonable interpretation that gives effect to the language in the statute and the underlying legislative intent. Congress intended the agencies administering section 101(a)(5)(A) to consider practicability when determining appropriate mitigation, but we do not believe the analysis must be conducted in such a rigid sequential fashion. There is a tension inherent in the phrase “least practicable adverse impact” in that “least [. . .] adverse impact” pulls in favor of one direction (
i.e.,
expanding mitigation) while “practicable” pulls in favor of the other direction (
i.e.,
limiting mitigation), and weighing the relative costs and benefits is, in our view, a more meaningful way to address and resolve this tension. Contrary to the Commission's suggestion, there is no formulaic way to do this. As we explained in the discussion of the LPAI standard above using a simple hypothetical example to illustrate the point, means of minimizing adverse impacts at the species or stock level is not a black and white proposition. Further, the standard is accomplished

through mitigation imposed for individuals—yet the standard does not require that we minimize individual takes or impacts to the maximum extent practicable.

NMFS' approach laid out in this rulemaking acknowledges that, even when the negligible impact standard is met, NMFS must still consider mitigation under the LPAI standard. NMFS' approach recognizes that impacts to species or stocks of marine mammals accrue through individuals and, as such, allows for reducing impacts on individuals, but with a focus on measures designed to avoid or minimize impacts on marine mammals that are likely to increase the probability or severity of population level effects. The greater the likelihood that a measure will contribute to reducing the probability or severity of adverse impacts to a species or stock, the greater the weight that measure is given when considered in combination with practicability to determine the appropriateness of a mitigation measure. While the analysis we describe can be conducted for each measure, we read the “means of effecting the LPAI” standard as ultimately applying to the totality of all required measures taken together. Accordingly, NMFS can take into account other measures that will be implemented when considering the benefit of additional measures. NMFS has weighed the relevant considerations as explained in its fuller discussion of LPAI.

While the Ninth Circuit's opinion in
Pritzker
(83 F.3d 1125 (9th Cir. 2016)) did not directly address this question, the Court appeared to view NMFS' conceptual approach of weighing various considerations as an acceptable one. In response to our 2012 rule, where we described our approach as including “a careful balancing of the likely degree to which the measure is expected to minimize adverse impacts to marine mammals with the likely effect of that measure on personnel safety, practicality of implementation, and impact on the effectiveness of military readiness activity,” the Court said “this formulation makes sense so far as it is stated,”
Pritzker,
828 F.3d at 1135 (emphasis added), though faulted NMFS for not meaningfully discussing how the measures it imposed would meet that standard. The legislative history on the 2004 MMPA amendments for military readiness activities provides further support, in that it shows Congress intended additional weighing for military readiness impacts and placed equal import on the military's need to conduct training activities. 2004 U.S.C.C.A.N. at 1447 (stating that the changes with the MMPA “properly balance the equities associated with military readiness and maritime species protection”).

Comment 15:
The Commission stated that section 101(a)(5)(A)(i)(II)(aa) of the MMPA specifies that incidental take regulations are to set forth permissible methods of taking pursuant to such activity, and other means of effecting the least practicable adverse impact on such species or stock and its habitat, paying particular attention to rookeries, mating grounds, and other areas of similar significance. The Commission stated that in this case, NMFS has only identified in the most general sense the means it will use to effect the least practicable adverse impact—it will identify and impose heightened protections in as yet unidentified OBIAs—and has provided no information to assess when and where NMFS believes it would be practicable for the Navy to abide by those exclusions. Only at the final rule stage would NMFS generate a list of the areas that meet the OBIA criteria, provide its rationale for determining which areas satisfy those criteria, and discuss whether requiring the Navy to employ mitigation measures in and near those areas would be practicable. The Commission stated that this approach is inconsistent with how NMFS has handled every previous rulemaking involving the Navy's activities, and more importantly, is inconsistent with the requirements of the Administrative Procedure Act (APA), which requires that NMFS give the public a meaningful opportunity to comment on what the agency is proposing. In this instance, the public is not being given a meaningful opportunity to comment on which OBIAs are appropriate to include in the final rule. Rather, commenters are left to speculate on which OBIAs NMFS might select and to comment in a vacuum as to whether those would be practicable for the Navy to meet its operational goals if some or all of the OBIAs that meet the criteria are included in the final rule. The Commission recommended that, in this and other proposed rules, NMFS inform the public what measures it is proposing to include in the final rule to satisfy the requirements of section 101(a)(5)(A)(i)(II)(aa) of the MMPA rather than leaving the public to speculate on all of the possibilities and the practicability of implementing them.

Response:
NMFS disagrees with both the Commission's description of the lack of information that NMFS provided the public in the proposed rule and the assertion that it was inconsistent with the requirements of the APA. NMFS described a clear proposed process and detailed set of factors that would be used to identify OBIAs, both prior to the finalization of the rule, as well as adaptively throughout the course of the rule. Further, NMFS provided the public with a carefully evaluated and honed list (reduced from hundreds considered, down to 25 presented) of potential OBIAs that preliminarily met the biological criteria (in addition to the four that were already established for the geographic areas included in the Study Area) to provide input on. NMFS systematically described these OBIA candidates in the context of the OBIA process and factors and indicated all of the references from which the supporting information was obtained. The public was given adequate information upon which to base input on this mitigation, as required by the APA. The fact that the practicability of these areas for the Navy was not discussed in the proposed rule did not prevent the public from providing meaningful input on the information and potential OBIAs presented.

Comment 16:
The Commission noted that the analysis provided in the
Federal Register
notice seems to conflate the species and habitat portions of the least practicable adverse impact standard. NMFS discussed the distinction between impacts on individual marine mammals versus impacts on species and stocks in some detail. However, that distinction is irrelevant when considering adverse impacts to important marine mammal habitat such as rookeries, mating grounds, and areas of similar significance. All of these types of areas are important at the species or stock level. Further, the Commission stated that it believes all of the areas that meet the OBIA designation criteria constitute important habitat for purposes of implementing section 101(a)(5)(A)(i)(II)(aa) of the MMPA and that mitigation measures to avoid or reduce adverse impacts to all of those areas should be included in the final rule unless such measures are not practicable. The Commission therefore recommended that, in the final rule, NMFS again require that the Navy ensure that none of the areas designated as OBIAs (or the 1 km buffer zones around them) are subjected to SURTASS LFA sonar received levels of 180 dB re 1 μPa or greater. Further, because the proposed rule did not include any information that indicates it would be impracticable for the Navy to adhere to such a limitation for any of the OBIAs under consideration, the Commission recommended that this mitigation

measure apply to all areas the Commission recommended be designated as OBIAs herein. If NMFS or the Navy believes it would be impracticable to implement the identified measures in any of those areas, then NMFS should make that case in a subsequent
Federal Register
notice and provide the public with an opportunity to comment on any proposed exceptions before adopting them.

Response:
NMFS disagrees with the Commission's assertion that NMFS conflates the species and habitat portions of the LPAI standard. NMFS recognizes the LPAI standard includes a requirement to prescribe measures that will effect the least practicable adverse impact on both the affected species or stocks and their habitat. In our description of implementation of the standard, we state that reduction of habitat impacts is relevant, particularly as it relates to rookeries, mating grounds, and areas of similar significance, and can include measures to reduce impacts of an activity on known prey utilized in the area or reducing impacts on physical habitat. Our discussion of least practicable adverse impact points out that because habitat value is informed by marine mammal presence and use, in some cases there may be overlap in measures for the species or stock and for use of habitat. Here we have identified time-area restrictions based on a combination of factors that include higher densities and observations of specific important behaviors of the animals themselves, but these also clearly reflect preferred habitat. In addition to being delineated based on physical features that drive habitat function (
e.g.,
bathymetric features, among others), the high densities and concentration of certain important behaviors (
e.g.,
feeding) in these particular areas clearly indicates the presence of preferred habitat. Just because the OBIAs address both marine mammals and their habitat does not mean that NMFS has conflated the two pieces of the standard. The MMPA does not specify that effects to habitat must be mitigated in separate measures, and NMFS has clearly identified measures that provide for mitigation of impacts to both marine mammal “species or stocks and their habitat,” as required by the statute.

Further, this rulemaking evaluated the effects of SURTASS LFA sonar activities on marine mammal habitat, specifically including prey, and concluded that marine mammal prey will not be exposed to sustained duration and intensity of sound levels that would result in significant adverse effects to marine mammal food resources. Accordingly, no additional mitigation for habitat beyond the geographic based measures identified to minimize impacts on the affected species or stocks while using/occurring in certain preferred habitat (such as OBIAs), or the coastal standoff range was warranted.

To the Commission's last point, in consideration of input from the public and our final evaluation, NMFS identified 17 areas (in the form of 14 OBIAs) as satisfying the necessary biological and geographic qualifications for OBIA designation and the Navy found that the implementation of all of these areas as OBIAs would be practicable. Accordingly, all 14 OBIAs are included in the final regulations.

Comment 17:
NRDC et al. expressed concern that NMFS, in its discussion of the LPAI standard, has set forth an interpretation that remains inconsistent with the plain language of the MMPA and with the Court's ruling in
Pritzker
(83 F.3d 1125 (9th Cir. 2016)). NRDC et al. stated that the agency reserves its consideration of mitigation measures to those that ultimately “are likely to increase the probability or severity of population-level effects” (84 FR 7228), and that it appears to base this understanding on an imputation of population-level harm into the “least practicable adverse impact” standard, and particularly into the standard's reference to “such species or stock.” NRDC et al. stated that the Court in
NRDC
v.
Pritzker
specifically rejected this assumption when the agency attempted to import it into the statute via its existing regulations concerning “negligible impact.” NRDC agreed with NMFS that the reduction of impacts to affected species or stocks “accrues through the application of mitigation measures that limit impacts to individual animals” and, consistent with this, “focuses on measures that are designed to avoid or minimize impacts on individual marine mammals” that, in turn, “are likely to increase the risk of population-level effects” (citing to 84 FR 7228). They cite as an example that the agency recognizes measures “limiting interruption of known feeding, breeding, mother/young, or resting behaviors” as having “greater value” for mitigation. However, NRDC stated that NMFS' formulation remains problematic in practice. NRDC stated that in detaching itself from the MMPA's “take provision,” it creates “vagueness that leaves the provision open to inconsistent, arbitrary application” and that the proposed rule appears to wander beyond the interpretation that NMFS sets down when it rejects the White Paper (
Identifying Areas of Biological Importance to Cetaceans in Data-Poor Regions
) guidelines to establish OBIAs in data-poor regions. NRDC et al. state that the proposed rule: “does so on the grounds [. . .] that establishing OBIAs would not further reduce fitness consequences (
i.e.,
`the potential for impacts on reproduction or survival') in individual marine mammals and thus would not reduce the probability of population-level harm. Id. at 7247. Yet this is an ostensibly higher bar than is articulated by the agency in its section interpreting the least practicable adverse impact standard, requiring actual reduction of fitness impacts rather than reduced disruption of behavioral responses associated with fitness. Compare
id.
at 7229 (listing factors having `greater value' for mitigation to include `limiting interruption of known feeding, breeding, mother/young, or resting behaviors'). Putting aside the inconsistency with the statute, discussed above, our practical concern is that NMFS' interpretation will be used as a convenient legal defense—just as it was in
Pritzker
—to prop up an insufficient analysis. NMFS should ensure that it applies the “least practicable adverse impact” standard in a manner that reduces the impacts (
e.g.,
Level A and Level B harassment take) that Congress intended to prohibit in adopting the MMPA.”

Response:
NMFS' interpretation and implementation of the LPAI standard is not inconsistent with the statute or the
Pritzker
decision, as described in the
Mitigation
section of this rule (and not re-included here). We interpret the LPAI standard as having a species or stock-level focus but believe the reduction of impacts to those species or stocks accrues through the application of mitigation measures that limit impacts to individual animals. Accordingly, NMFS' analysis focuses on measures that are designed to avoid or minimize impacts on individual marine mammals that are likely to increase the probability or severity of population-level effects. NMFS acknowledges that it is not a mathematical formula; in evaluating a measure, consideration of its value and its practicability will necessarily involve exercise of the agency's professional judgment taking into account the specified activity and other contextual factors. NMFS' rule fully discusses its evaluation applying the standard it sets forth. Moreover, there is no inconsistency in the standard and the application in view of the full discussion in this rule. The language quoted in the comment cannot be isolated from the context of the full

discussion in the rule and then cited as proof of inconsistency. Specifically, to support its assertion, NRDC points to our rationale for not adopting the recommendations in the White Paper (discussed in detail in the
Mitigation
section). The comment mischaracterizes our conclusions by suggesting our reasoning is based solely on the fact that the recommendations in the White Paper will not further reduce fitness consequences of individuals and thus would not reduce population level harm. This ignores the fuller discussion, in which our assessment shows that the proposed mitigation would add little, if any, value for lowering the probability or severity of impacts to individual marine mammal fitness, but also that it is highly impracticable for the Navy. Thus, the White Paper recommendations were not adopted based on a straightforward application of the LPAI standard.

Procedural Mitigation Effectiveness and Recommendations

Comment 18:
The Commission recommended that, in the final rule, NMFS require the Navy to (1) use a 30-minute clearance time when a marine mammal has not been observed to have left the mitigation zone, consistent with other Navy activities and (2) conduct post-activity monitoring including visual, passive acoustic, and active acoustic monitoring for 30 rather than 15 minutes.

Response:
A 30-minute post monitoring timeframe is more widely used in other authorizations mainly due to the fact that marine mammal detections are largely reliant on visual surveys and this time accounts for marine mammals with longer-duration dives. In addition to visual and passive acoustic monitoring, the HF/M3 (active acoustic monitoring system) is used with SURTASS LFA sonar activities. Detection through active acoustics is typically not used with authorizations for other activities. However, given the near 100 percent effectiveness of the HF/M3 system with multiple pings (see response to Comment 7), in combination with the two other mitigation monitoring efforts (visual and passive acoustic monitoring), NMFS feels confident that any marine mammals present in the mitigation zone would be detected within the 15-minute timeframe.

Comment 19:
The Commission noted that it does not appear that the Navy has conducted a study to investigate the effectiveness of the suite of mitigation measures currently being employed or proposed for SURTASS LFA sonar activities and that such a study would be prudent. The Commission noted that determination of effectiveness has been based solely on what has been “observed” via the three monitoring methods and some theoretical assumptions. True “effectiveness” studies evaluate not only the animals that are detected, but also those that are missed. The Navy is conducting a lookout effectiveness study to assess the effectiveness of visual monitoring. A similar study, including the assessment of both passive and active acoustic monitoring, would provide a more appropriate means than the Navy's current approach for concluding that the measures are 100 percent effective.

Response:
The effectiveness of the HF/M3 sonar system to monitor and detect marine mammals has been assessed. Details on this assessment and the effectiveness of the HF/M3 system are provided in a technical report by Ellison and Stein (2001), the 2001 SURTASS LFA FOEIS/EIS (see subchapters 2.3.2.2 and 4.2.7.1 for the HF/M3 sonar testing results), as well as Chapter 4, Section 5.4.3 of the 2019 SURTASS LFA FSEIS/SOEIS. The study qualitatively and quantitatively assessed the HF/M3 system's ability to detect marine mammals of various sizes with 170 hours of at-sea testing, including trials off the coast of San Diego with trained bottlenose dolphins, as well as several developmental tests with artificial targets (which allowed for examination of whether these methods potentially miss animals). The results indicate a near 100 percent probability of detecting marine mammals before they enter the LFA mitigation zone. As noted by the commenter, the Navy continues to assess the effectiveness of its mitigation measures. The results of any new studies will be assessed through the Adaptive Management process. NMFS acknowledges the limitations associated with visual and passive acoustic monitoring, but together with the near 100 percent effectiveness of active acoustic monitoring with the HF/M3 sonar system, NMFS has determined that these mitigation monitoring measures are highly effective.

Comment 20:
NRDC et al. noted that the proposed mitigation distance resulting in sound pressure levels within OBIAs and coastal exclusion zones not to exceed 180 dB re 1 μPa (rms) bears no relation to the Navy's behavioral response function, even though the agencies have repeatedly identified behavioral disruption as the primary marine mammal impact of concern from LFA sonar, or to any qualitative assessment of stress response or masking effects. NRDC et al. noted that it roughly reflects the Navy's threshold for the onset of auditory injury per NMFS guidance. NRDC et al. stated that the 180 dB threshold fails to meaningfully protect marine mammals from the behavioral impacts that the agencies have repeatedly characterized as the impacts of primary concern. They noted that according to prior Navy analysis, the 175-180 dB (rms) annulus has an average “take” risk of 91.5 percent, the 170-175 dB (rms) annulus a take risk of 80.5 percent, the 165-170 dB (rms) annulus a risk of 61.5 percent, the 160-165 dB annulus a risk of 38.5 percent (rms), the 155-160 dB annulus a risk of 18 percent, and the 150-155 dB annulus a risk on the order of 8-9 percent (see 2007 SEIS at 4-74). They stated that given the greater area subsumed within the lower-decibel annuluses, the number of takes occurring within even the 150 dB annulus can be high, despite the lower relative risk. NRDC et al. stated that the geographic sound field operational constraints designed to eliminate LFA exposures out to at least 150 dB (rms) are likely to be practicable for most, if not all, OBIAs, as the Navy already avoids dive sites out to 145 dB (rms) (DSEIS at 5-5), nominally requiring a greater mitigation distance than a 150 dB (rms) standoff would entail. They stated that the Navy's broad claim of impracticability for any mitigation threshold lower than 180 dB exemplifies the non-rigorous rationalizing that the court in
Conservation Council
found unconvincing and unsupportable under the MMPA (See 97 F.Supp.3d at 1229-31). NRDC et al. stated that NMFS' “practicability criterion” requires a site-specific discussion, with the Navy, of any OBIA that the Navy initially determines to be impracticable, to see if a modification of the OBIA can address the issue. They recommended that the Navy and NMFS presumptively adopt a 150 dB (rms) mitigation distance from each OBIA, except where geographically specific, clearly stated operational needs make such a distance impracticable, in which case it should adopt the largest practicable distance, to be determined on a case-by-case basis according to the procedure set forth in the “practicability criterion.”

Response:
After the development of NMFS' 2018 Acoustic Technical Guidance, NMFS and the Navy reevaluated the use of 180 dB re: 1 μPa rms as the basis for the LFA mitigation zone and concluded that 180 dB would be retained as the mitigation basis (see the
Mitigation
section of this final rule and Chapter 5, Section 5.2 of the 2019

SURTASS LFA FSEIS/SOEIS for details on this reevaluation). However, in consideration of updated PTS and TTS thresholds, the 180 dB threshold for the OBIA and the coastal exclusion zone boundaries is expected to preclude not only PTS at the outer perimeter of these areas, but also likely some instances of TTS and more severe forms of Level B harassment by behavioral disruption. Moreover, the 180 dB threshold applies at a distance 1 km from OBIA boundaries, further reducing exposure levels at the OBIA perimeters to approximately 174 dB. In addition, the likelihood and severity of behavioral harassment is further reduced within these important areas as maximum received levels in these areas are even lower the farther an animal is from the perimeter and the farther the vessel is from the edge. In other words, while an individual in the coastal exclusion zone might be exposed to levels as high as 180 dB (174 dB if in an OBIA, given the 1 km buffer) briefly if animal is at the edge and a SURTASS LFA vessel has approached at the closest allowable distance from the edge—the majority of individuals within the area will always be exposed to levels increasingly lower than that (the farther they are from the edge), plus the vast majority of the time SURTASS LFA vessels will not be right at the edge. Therefore, while this mitigation measure based on 180 dB will not totally avoid all takes within OBIAs, it will meaningfully reduce both the number and severity of takes within these important areas significantly by ensuring that the majority of individual marine mammals within these areas are exposed to lower levels with lower probabilities of being taken, and less severe responses if the take occurs.

Regarding the comments about practicability, NMFS and the Navy have thoroughly evaluated the practicability of all of the mitigation measures, including the OBIAs and their associated 180-dB zones, and in consideration of public comments have added an additional measure to further minimize behavioral harassment within OBIAs. Specifically, no more than 25 percent of the authorized amount of SURTASS LFA sonar will be used for training and testing within 10 nmi (18.5 km) of any single OBIA during any year unless it is required for national security, permission is obtained from the appropriate designated Command authority prior to commencement of the activity, NMFS is notified as soon as is practicable, and these sonar hours are reported in annual activity reports. This measure ensures that exposures (and thereby probability and severity of Level B harassment) to LFA sonar of individuals within OBIAs will be even further limited, both in received level and time. Specifically, the already protective circumstances described for OBIAs above will be in place up until an OBIA has been exposed to LFA sonar for 124-148 hours per year; beyond that number of hours, the maximum received level an individual may be exposed to (when both the animal is at the edge and the vessel at its closest approach) would be substantially reduced and, as described above, any marine mammals further within the OBIA would be exposed to even lower levels, and even lower when the vessel is not right at the edge.

Further, it is inappropriate to compare the 145-dB zone around dive sites to the 180-dB zone around OBIAs, as they have different purposes and are subject to different requirements. Whereas the goal of the 145-dB zone around dive sites is generally to avoid any impacts to human divers and is in no way associated with the requirements of the MMPA, take of marine mammals is expected and authorized to occur, but as required by the MMPA, NMFS and the Navy have ensured that the extensive suite of measures required will effect the least practicable adverse impact.

Comment 21:
NRDC et al. stated that the criteria NMFS adopted [NMFS' Acoustic Technical Guidance], following the Navy, to estimate temporary and permanent threshold shift in marine mammals are erroneous and non-conservative. They stated that Wright (2015) identified several statistical and numerical faults in the Navy's approach, such as pseudo-replication and inconsistent treatment of data that tend to bias the proposed criteria towards an underestimation of effects. NRDC et al. stated that similar and additional issues were raised by a dozen scientists during the public comment period on the draft Acoustic Technical Guidance held by NMFS and noted that at the root of the problem is the agencies' broad extrapolation from a small number of individual animals, mostly bottlenose dolphins, without taking account of what Racca et al. (2015) have succinctly characterized as a “non-linear accumulation of uncertainty.”

Response:
NMFS disagrees with this characterization of the Acoustic Technical Guidance and the associated recommendation. The Acoustic Technical Guidance is a compilation, interpretation, and synthesis of the scientific literature that provides the best scientific information regarding the effects of anthropogenic sound on marine mammals' hearing. The Technical Guidance was classified as a Highly Influential Scientific Assessment and, as such, underwent three independent peer reviews, at three different stages in its development, including a follow-up to one of the peer reviews, prior to its dissemination by NMFS. In addition, there were three separate public comment periods, during which time we received and responded to similar comments on the guidance (81 FR 51694; August 4, 2016), which we cross-reference here, and more recent public and interagency review under Executive Order 13795. This review process was scientifically rigorous and ensured that the Guidance represents the best scientific data available. Furthermore, the recent peer-reviewed updated marine mammal noise exposure criteria by Southall
et al.
(2019) provide identical PTS and TTS thresholds to those provided in NMFS' Acoustic Technical Guidance.

NMFS disagrees with any suggestion that the use of the Acoustic Technical Guidance provides erroneous results. The use of the 180-dB rms threshold to identify where PTS would occur is plainly outdated, as the best available science indicates that rms SPL is not an appropriate metric by which to gauge potential auditory injury (whereas the scientific debate regarding thresholds for Level B harassment by behavioral disruption is not about the proper metric but rather the proper level or levels and how these may vary in different contexts).

Regarding the suggestion that the thresholds are non-conservative, multiple studies from humans, terrestrial mammals, and marine mammals have demonstrated less TTS from intermittent exposures compared to continuous exposures with the same total energy because hearing is known to experience some recovery in between noise exposures, which means that the effects of intermittent noise sources such as tactical sonars are likely overestimated. Marine mammal TTS data have also shown that, for two exposures with equal energy, the longer duration exposure tends to produce a larger amount of TTS. Most marine mammal TTS data have been obtained using exposure durations of tens of seconds up to an hour, much longer than the durations of many tactical sources (much less the continuous time that a marine mammal in the field would be exposed consecutively to those levels), further suggesting that the use of these TTS data are likely to overestimate the effects of sonars with shorter duration signals.

Regarding the suggestion of pseudo-replication and erroneous models, since

marine mammal hearing and noise-induced hearing loss data are limited, both in the number of species and in the number of individuals available, attempts to minimize pseudo-replication would further reduce these already limited data sets. Specifically, with marine mammal behavioral temporary threshold shift studies, behaviorally derived data are only available for two mid-frequency cetacean species (bottlenose dolphin, beluga) and two phocids (in-water) pinniped species (harbor seal and northern elephant seal), with otariid (in-water) pinnipeds and high-frequency cetaceans only having behaviorally-derived data from one species. Arguments from Wright (2015) regarding pseudo-replication within the TTS data are therefore largely irrelevant in a practical sense because there are so few data points. Multiple data points were not included for the same individual at a single frequency. If multiple data points existed at one frequency, the lowest TTS onset was always used. There is only a single frequency where TTS onset data exist for two individuals of the same species: 3 kHz for dolphins. Their TTS (unweighted) onset values were 193 and 194 dB re 1 μPa
2
s. Thus, NMFS believes that the current approach makes the best use of the given data. Appropriate means of reducing pseudo-replication may be considered in the future, if more data become available. Many other comments from Wright (2015) and the comments from Racca et al. (2015b) appear to be erroneously based on the idea that the shapes of the auditory weighting functions and TTS/PTS exposure thresholds are directly related to the audiograms;
i.e.,
that changes to the composite audiograms would directly influence the TTS/PTS exposure functions (
e.g.,
Wright (2015) describes weighting functions as “effectively the mirror image of an audiogram” (p. 2) and states, “The underlying goal was to estimate how much a sound level needs to be above hearing threshold to induce TTS.” (p. 3)). Both statements are incorrect and suggest a fundamental misunderstanding of the criteria/threshold derivation. This would require a constant (frequency-independent) relationship between hearing threshold and TTS onset that is not reflected in the actual marine mammal TTS data. Attempts to create a “cautionary” outcome by artificially lowering the composite audiogram thresholds would not necessarily result in lower TTS/PTS exposure levels, since the exposure functions are to a large extent based on applying mathematical functions to fit the existing TTS data.

Comment 22:
NRDC et al. stated the proposed rule gives little consideration to expanding the LFA coastal exclusion zone, assuming, based on its analysis in prior environmental reviews, that its standoff distance should remain 12 nmi from shore. The commenters stated that this reliance on prior analyses is not supportable.

Response:
As described in the
Mitigation
section, the Navy's 2007 SURTASS LFA FSEIS/SOEIS evaluated increasing the coastal standoff distance up to 46 km (25 nmi). Based on a six-step analysis process, its analysis showed that increasing the coastal standoff range would decrease exposure to higher received levels for concentrations of marine animals closest to shore, but would do so at the expense of increasing exposure levels for shelf break and pelagic species. This result is due to the reduced overlap of the exposure area with land leading to an increase in exposure area as the sound source moves farther offshore. There have been no changes to the best available scientific information or other indications that the coastal standoff distance should be increased since this analysis; therefore, there is no change in this mitigation measure from previous rulemakings. Nonetheless, it is also erroneous to say that the new rule gives no consideration to further extending the coastal exclusion, given the extensive analysis of the White Paper (see
Mitigation
section and response to Comment 23 immediately below), which included a recommendation for a larger coastal exclusion. As noted in the 2012 final rule (77 FR 50290; August 20, 2012), over 80 percent of the existing and potential marine protected areas reviewed were within 12 nmi from a coastline, indicating the effectiveness of the coastal standoff as one of the primary mitigation measures for reducing potential impacts to marine mammals. OBIAs expand upon this protection by avoiding or minimizing impacts in areas beyond the coastal standoff distance where marine mammals are known to engage in specific behaviors that may lead to more severe impacts if interrupted; known to congregate in higher densities; and/or known to have a limited range and small abundance that creates more vulnerability for the stock as a whole. These criteria are important when determining whether mitigation would be likely to reduce the probability of effects to individuals that would translate to minimization of impacts at the population level under the LPAI standard.

Comment 23:
NRDC et al. noted that they have called on the Navy and NMFS to adopt a more expansive, more biologically meaningful coastal exclusion, particularly one that protects the continental shelf and slope with a standoff from the shelf break. They noted that NMFS' own subject-matter experts, in the White Paper, recommend that, absent specific data to the contrary, “all continental shelf waters and waters 100 km of the continental slope should be designated as biologically important habitat for marine mammals.” They recommended that NMFS, in consultation with the Navy, should consider alternative coastal exclusion areas.

Response:
NMFS carefully considered the White Paper's recommendations and we present an evaluation of the White Paper's recommendation to restrict LFA sonar transmissions from all continental shelf waters and waters 100 km seaward of continental slope in the
White Paper Specific Recommendations
subsection of the
Mitigation
section. As discussed in this section, given the other mitigation measures we are requiring, takes of marine mammals would be limited to Level B harassment in the less severe range of behavioral reactions and some TTS, as described above. Consequently, the only additional anticipated value to restricting SURTASS LFA sonar activities in continental shelf waters and waters 100 km seaward of continental slope would be some potential, though not certain or significant, reduction in the number of less severe behavioral reactions in those areas. In general, not all behavioral responses rise to the level of a take and not all harassment takes result in fitness consequences to individuals that have the potential to translate to population consequences to the species or stock. Given the anticipated impacts of SURTASS LFA sonar, there is little to no likelihood that the impacts of the anticipated takes would accrue in a manner that would impact a species or stock even in the absence of any additional mitigation. Considered with the uncertain potential of this proposed recommendation to provide meaningful incremental reduction of risk or severity of impacts to individual marine mammals, NMFS concludes that this recommendation would not reasonably be expected to provide a reduction in the probability or degree of effects on any marine mammal species or stocks. Moreover, NMFS discusses why the measure would not be practicable for the Navy to implement. NMFS acknowledges that while these measures could potentially reduce the numbers of

takes of some individual marine mammals within a limited number of species, or could add some small degree of protection to preferred habitat or feeding behaviors in certain circumstances, this limited and uncertain benefit did not justify adopting the White Paper's recommendations considering the existing mitigation measures already implemented by the Navy and the high degree of impracticality for Navy implementation.

Offshore Biologically Important Areas (OBIAs)

OBIA Criteria/Evaluation Process

Comment 24:
The Commission noted that a lack of data or insufficient data regarding marine mammal presence and abundance is not an adequate basis for failing to adopt precautionary measures, especially when such data are not available for most of the world's oceans. The Commission noted it made this point in its 2011 letter on a previous DSEIS and the U.S. Court of Appeals for the Ninth Circuit remanded the SURTASS LFA sonar case on that basis. The Commission stated that the Ninth Circuit indicated that NMFS and the Navy should have considered whether a precautionary approach would give more protection to marine mammals, and then whether that protection would impede military training to a degree that makes such mitigation impracticable. The Commission stated that it appears that NMFS is failing to take a sufficiently precautionary approach, particularly with respect to the Pacific Remote Island MNM.

Response:
We acknowledge that the Ninth Circuit opinion stated that NMFS “should have considered whether `the precautionary approach' would give more protection to marine mammals, and then whether that protection would impede military training to a degree making that mitigation not practicable.”
Pritzker,
828 F.3d at 1138. The Court went on to fault NMFS for not considering the White Paper's recommendations. Taken in the context of the Court's full discussion, however, we read the Ninth Circuit's use of the term “the precautionary approach” as specifically referring to the recommendations in the White Paper for designating OBIAs in “data-poor” regions of the ocean (described therein as a precautionary approach for designating OBIAs), rather than a broader mandate to adopt a “precautionary approach” in carrying out the requirements of the statute.

In response to the Ninth Circuit's opinion and in the context of the LPAI standard, for this rulemaking NMFS directly considered the White Paper recommendations (see discussion of the White Paper recommendation in the
Mitigation
section). We considered the factors as instructed by the Court, although we ultimately did not adopt the White Paper's recommendations.

NMFS' interpretation of the Ninth Circuit's opinion is based on the fact that neither the MMPA nor NMFS' implementing regulations include references to, or requirements for, the precautionary approach, nor is there a clear, agreed-upon description of what the precautionary approach is or would entail in the context of the MMPA or any specific activity. Nevertheless, the MMPA by nature is inherently protective, including the requirement to mitigate to the lowest level practicable (“least” practicable adverse impacts,

[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%3A2019-16695. Public record. Not legal advice.