Taking and Importing Marine Mammals; Taking Marine Mammals Incidental to the U.S. Navy Training and Testing Activities in the Point Mugu Sea Range Study Area

DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

50 CFR Part 218

[220629-0147]

RIN 0648-BK07

Taking and Importing Marine Mammals; Taking Marine Mammals Incidental to the U.S. Navy Training and Testing Activities in the Point Mugu Sea Range Study Area

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 training and testing activities conducted in the Point Mugu Sea Range (PMSR) Study Area. The Navy's activities qualify as military readiness activities pursuant to the MMPA, as amended by the National Defense Authorization Act for Fiscal Year 2004 (2004 NDAA). 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 and their habitat, and establish requirements pertaining to the monitoring and reporting of such taking.

DATES:

Effective from July 7, 2022, through July 7, 2029.

ADDRESSES:

A copy of the Navy's application, NMFS' proposed and final rules and subsequent LOA for the existing regulations, and other supporting documents and documents cited herein 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 use the contact listed here (see

FOR FURTHER INFORMATION CONTACT

).

FOR FURTHER INFORMATION CONTACT:

Leah Davis, Office of Protected Resources, NMFS, (301) 427-8401.

SUPPLEMENTARY INFORMATION:

Purpose of Regulatory Action

These regulations, issued under the authority of the MMPA (16 U.S.C. 1361

et seq.

), provide the framework for authorizing the take of marine mammals incidental to the Navy's training and testing activities (which qualify as military readiness activities) from the use of at-surface and near-surface explosive detonations throughout the PMSR Study Area, as well as launch events from San Nicolas Island (SNI). The PMSR Study Area includes 36,000 square miles and is located adjacent to Los Angeles, Ventura, Santa Barbara, and San Luis Obispo Counties along the Pacific Coast of Southern California (see Figure 1.1 of the application). The two primary components of the PMSR are the Special Use Airspace (SUA) and the ocean Operating Areas (PMSR-controlled sea space). The PMSR-controlled sea space parallels the California coast for approximately 225 nautical miles (nmi) (417 km) and extends approximately 180 nmi seaward (333 km; see Figure 1-1 of the application).

NMFS received an application from the Navy requesting 7-year regulations and an authorization to incidentally take individuals of multiple species of marine mammals (“Navy's rulemaking/LOA application” or “Navy's application”). Take is anticipated to occur by Level A harassment and Level B harassment incidental to the Navy's training and testing activities, with no serious injury or mortality anticipated or authorized.

Section 101(a)(5)(A) of the MMPA (16 U.S.C. 1371(a)(5)(A)) directs the Secretary of Commerce (as delegated to NMFS) to allow, upon request, the incidental, but not intentional taking of small numbers of marine mammals by U.S. citizens who engage in a specified activity (other than commercial fishing) within a specified geographical region if, after notice and public comment, the agency makes certain findings and issues regulations that set forth permissible methods of taking pursuant to that activity, 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 the subsequent LOA. As directed by this legal authority, this final rule contains mitigation, monitoring, and reporting requirements.

Summary of Major Provisions Within the Final Rule

The following is a summary of the major provisions of this final rule regarding the Navy's activities. Major provisions include, but are not limited to:

Measures to reduce the probability and/or severity of impacts expected to result from exposure to explosives and launch activities (

i.e.,

minimize the likelihood or severity of permanent threshold shift or other injury, and reduce instances of temporary threshold shift or more severe behavioral disruption caused by explosives and launch activities);

Activity limitations in certain areas and times that are biologically important (

e.g.,

pupping season on San Nicolas Island) for marine mammals;

Measures to reduce the likelihood of ship strikes;

Implementation of a Notification and Reporting Plan (for dead or live stranded marine mammals); and

Implementation of a robust monitoring plan to improve our understanding of the environmental effects resulting from the Navy training and testing activities.

Additionally, the rule includes an adaptive management component that allows for timely modification of mitigation or monitoring measures based on new information, when appropriate.

Background

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

An authorization for incidental takings shall be granted if NMFS finds that the taking will have a negligible impact on the species or stocks and will not have an unmitigable adverse impact on the availability of the species or stocks 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 this rule as “mitigation measures”). NMFS also must prescribe the requirements pertaining to the monitoring and reporting of such takings. The MMPA defines “take” to mean to harass, hunt, capture, or kill, or attempt to harass, hunt, capture, or kill any marine mammal. The

Analysis and Negligible Impact Determination

section below discusses the definition of “negligible impact.”

The NDAA for Fiscal Year 2004 (2004 NDAA) (Pub. L. 108-136) amended section 101(a)(5) of the MMPA to remove the “small numbers” and “specified geographical region” provisions indicated above and amended the definition of “harassment” as applied to a “military readiness activity.” The definition of harassment for military readiness activities (section 3(18)(B) of the MMPA) is: (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 2004 NDAA amended the MMPA as it relates to military readiness activities such that the least practicable adverse impact analysis shall include consideration of personnel safety, practicality of implementation, and impact on the effectiveness of the military readiness activity.

More recently, section 316 of the NDAA for Fiscal Year 2019 (2019 NDAA) (Pub. L. 115-232), signed on August 13, 2018, amended the MMPA to allow incidental take rules for military readiness activities under section 101(a)(5)(A) to be issued for up to 7 years. Prior to this amendment, all incidental take rules under section 101(a)(5)(A) were limited to 5 years.

Summary and Background of Request

On March 9, 2020, NMFS received an application from the Navy for authorization to take marine mammals by Level A harassment and Level B harassment incidental to training and testing activities (categorized as military readiness activities) from (1) the use of at-surface or near-surface explosive detonations in the PMSR Study Area, as well as (2) launch events from SNI, over a 7-year period beginning June 2022 through June 2029. We received a revised application on August 28, 2020, which provided minor revisions to the mitigation and monitoring sections, and upon which the Navy's rulemaking/LOA application was found to be adequate and complete. On September 4, 2020, we published a notice of receipt (NOR) of application in the

Federal Register

(85 FR 55257), requesting comments and information related to the Navy's request for 30 days. On July 16, 2021, we published a notice of proposed rulemaking (86 FR 37790) and requested comments and information related to the Navy's request for 45 days (“PMSR proposed rule”). All comments received during the NOR and the proposed rulemaking comment periods were considered in this final rule. Comments received on the proposed rule are addressed in this final rule in the

Comments and Responses

section.

The following types of training and testing, which are classified as military readiness activities pursuant to the MMPA, as amended by the 2004 NDAA, will be covered under the regulations and LOA: air warfare (air-to-air, surface-to-air), electronic warfare (directed energy—lasers and high-powered microwave systems), and surface warfare (surface-to-surface, air-to-surface, and subsurface-to surface). The activities will not include any underwater detonations, sonar, pile driving/removal, or use of air guns.

The Navy's mission is to organize, train, equip, and maintain combat-ready naval forces capable of winning wars, deterring aggression, and maintaining freedom of the seas. This mission is mandated by Federal law (10 U.S.C. 8062), which requires the readiness of the naval forces of the United States. The Navy executes this responsibility by training and testing at sea, often in designated operating areas (OPAREA) and testing and training ranges. The Navy must be able to access and utilize these areas and associated sea space and air space in order to develop and maintain skills for conducting naval operations. The Navy's testing activities ensure naval forces are equipped with well-maintained systems that take advantage of the latest technological advances. The Navy's research and acquisition community conducts military readiness activities that involve testing. The Navy tests ships, aircraft, weapons, combat systems, sensors, and related equipment, and conducts scientific research activities to achieve and maintain military readiness.

The Navy has been conducting testing and training activities in the PMSR Study Area since the PMSR was established in 1946. The tempo and types of training and testing activities fluctuate because of the introduction of new technologies, the evolving nature of international events, advances in warfighting doctrine and procedures, and changes in force structure (

e.g.,

organization of ships, submarines, aircraft, weapons, and personnel). Such developments influence the frequency, duration, intensity, and location of required training and testing activities. The activities include current activities, previously analyzed in the 2002 PMSR Environment Impact Statement/Overseas Environmental Impact Statement (EIS/OEIS), and increases in the testing and training activities as described in the 2022 PMSR Final EIS/OEIS (FEIS/OEIS). NMFS promulgated MMPA incidental take regulations relating to missile launches from SNI from June 3, 2014, through June 3, 2019 (79 FR 32678; June 6, 2014). Since then, the Navy has been operating under incidental harassment authorizations (IHAs) (84 FR 28462, June 19, 2019; 85 FR 38863, June 29, 2020; and 86 FR 32372, June 21, 2021) for those similar activities on SNI. For this rulemaking, the Navy is requesting authorization for marine mammal take incidental to activities on SNI similar to those they have conducted under these and previous authorizations, as well as the use of at-surface and near-surface explosive detonations throughout the PMSR Study Area. The testing and training activities are deemed necessary to accomplish Naval Air System Command's mission of providing for the safe and secure collection of decision-quality data; and developing, operating, managing and sustaining the interoperability of the Major Range Test Facility Base at the PMSR into the foreseeable future.

The Navy's rulemaking/LOA application reflects the most up-to-date compilation of training and testing activities deemed necessary to accomplish military readiness requirements. The types and numbers of activities included in the rule account for fluctuations in training and testing in order to meet evolving or emergent military readiness requirements. These regulations will cover training and testing activities over a 7-year period beginning June 2022.

Description of the Specified Activity

A detailed description of the specified activity was provided in our

Federal Register

notice of proposed rulemaking (86 FR 37790; July 16, 2021); please see that notice of proposed rulemaking or the Navy's application for more information. The Navy has determined that explosive stressors and missile launch activities are most likely to result in impacts on marine mammals that could rise to the level of

harassment, and NMFS concurs with this determination. Descriptions of these activities are provided in section 2 of the 2021 PMSR FEIS/OEIS (U.S. Department of the Navy, 2021) and in the Navy's rulemaking/LOA application (

https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-military-readiness-activities

), and are summarized here.

Dates and Duration

The specified activities can occur at any time during the 7-year period of validity of the regulations, with the exception of the activity types and time periods for which limitations have explicitly been identified (to the maximum extent practicable; see

Mitigation Measures

section). The amount of training and testing activities are described in the

Detailed Description of the Specified Activity

section (Table 1).

Geographical Region

The PMSR Study Area is located adjacent to Los Angeles, Ventura, Santa Barbara, and San Luis Obispo Counties along the Pacific Coast of Southern California and includes a 36,000-square-mile sea range (see Figure 1 of the proposed rule). It is a designated Major Range Test Facility Base and is considered a national asset that exists primarily to provide test and evaluation information for Department of Defense (DoD) decision makers and to support the needs of weapon system development programs and DoD research needs. The two primary components of the PMSR Study Area are Special Use Airspace and the ocean Operating Areas. Additional detail can be found in Chapter 2 of the Navy's rulemaking/LOA application. The Navy plans to conduct launch activities on San Nicolas Island (SNI), California, for testing and training activities associated with operations within the PMSR Study Area.

Overview of Training and Testing Within the PMSR Study Area

The Navy categorizes its at-sea activities into functional warfare areas called primary mission areas. Each warfare community may train in some or all of these primary mission areas. The Navy also categorizes most, but not all, of its testing activities under these primary mission areas. Activities addressed for the PMSR Study Area are categorized under three primary mission areas: Air warfare (air-to-air, surface-to-air); Electronic warfare (directed energy—lasers and high-powered microwave systems); and Surface warfare (surface-to-surface, air-to-surface, and subsurface-to-surface). Within those three primary mission areas, there are more specific categories or activity scenarios that reflect testing and training activities. A description of the munitions, targets, systems, and other material used during training and testing activities within these primary mission areas is provided in Appendix A (Training and Testing Activities Descriptions) of the 2022 PMSR FEIS/OEIS.

The Navy also plans to continue a target and missile launch program from two launch sites on SNI for testing and training activities associated with operations within the PMSR Study Area. Missiles vary from tactical and developmental weapons to target missiles used to test defensive strategies and other weapons systems. Some launch events involve a single missile or target, while others involve the launch of multiple missiles or targets in quick succession. Missiles or targets launched from SNI fly generally west, southwest, and northwest through the PMSR Study Area. The primary launch locations are the Alpha Launch Complex, located 190 meters (m) above sea level on the west-central part of SNI and the Building 807 Launch Complex, which accommodates several fixed and mobile launchers, at the western end of SNI at approximately 11 m (12 yd) above sea level.

Description of Stressors

The Navy uses a variety of platforms, weapons, and other devices, including ones used to ensure the safety of Sailors and Marines, to meet its mission. Training and testing with these systems may introduce acoustic (sound) energy or shock waves from explosives into the environment. The following subsections describe explosives detonated at or near the surface of the water and launch noise associated with missiles launched from SNI for marine mammals and their habitat (including prey species) within the PMSR Study Area. Because of the complexity of analyzing sound propagation in the ocean environment, the Navy relied on acoustic models in its environmental analyses and rulemaking/LOA application that considered sound source characteristics and varying ocean conditions across the PMSR Study Area. Stressor/resource interactions that were determined to have de minimis or no impacts (

i.e.,

vessel, aircraft, or weapons noise) were not carried forward for analysis in the Navy's rulemaking/LOA application. NMFS reviewed the Navy's analysis and conclusions on de minimis sources and finds them complete and supportable.

Acoustic stressors include incidental sources of broadband sound produced as a byproduct of vessel movement and use of weapons or other deployed objects. Explosives also produce broadband sound but are characterized separately from other acoustic sources due to their unique hazardous characteristics. There are no sonar activities planned in the PMSR Study Area. Characteristics of explosives are described below.

In order to better organize and facilitate the analysis of various explosives used for training and testing by the Navy, including sonar and other transducers and explosives, a series of source classifications, or source bins, was developed by the Navy. The source classification bins do not include the broadband sounds produced incidental to vessel or aircraft transits, weapons firing, and bow shocks.

The use of source classification bins provides the following benefits:

Provides the ability for new sensors or munitions to be covered under existing authorizations, as long as those sources fall within the parameters of a bin;

Improves efficiency of source utilization data collection and reporting requirements anticipated under the MMPA authorizations;

Ensures a conservative approach to all impact estimates, as all sources within a given class are modeled as the most impactful source (having the largest net explosive weight) within that bin;

Allows analyses to be conducted in a more efficient manner, without any compromise of analytical results; and

Provides a framework to support the reallocation of source usage (number of explosives) between different source bins, as long as the total numbers of takes remain within the overall analyzed and authorized limits. This flexibility is required to support evolving Navy training and testing requirements, which are linked to real world events.

Explosives

This section describes the characteristics of explosions during naval training and testing. The activities analyzed in the Navy's rulemaking/LOA application that use explosives are described in Appendix A (PMSR Scenario Descriptions) of the 2022 PMSR FEIS/OEIS.

To more completely analyze the results predicted by the Navy's acoustic effects model from detonations occurring in-air above the ocean surface, it is necessary to consider the transfer of energy across the air-water interface.

Detonation of an explosive in air creates a supersonic high pressure shock wave that expands outward from the point of detonation (Kinney and Graham, 1985; Swisdak, 1975). The near-instantaneous rise from ambient pressure to an extremely high peak pressure is what makes the explosive shock wave potentially injurious to an animal experiencing the rapid pressure change (U.S. Department of the Navy, 2017e). Farther from an explosive, the peak pressures decay and the explosive waves propagate as an impulsive, broadband sound. As the shock wave-front travels away from the point of detonation, it slows and begins to behave as an acoustic wave-front travelling at the speed of sound. Whereas a shock wave from a detonation in-air has an abrupt peak pressure, that same pressure disturbance when transmitted through the water surface results in an underwater pressure wave that begins and ends more gradually compared with the in-air shock wave, and diminishes with increasing depth and distance from the source (Bolghasi

et al.

2017; Chapman and Godin, 2004; Cheng and Edwards, 2003; Moody, 2006; Richardson

et al.

1995; Sawyers, 1968; Sohn

et al.

2000; Swisdak, 1975; Waters and Glass, 1970; Woods

et al.

2015). The propagation of the shock wave in air and then transitioning underwater, is very different from a detonation occurring deep underwater where there is little interaction with the surface. In the case of an underwater detonation occurring just below the surface, a portion of the energy from the detonation would be released into the air (referred to as surface blow off), and at greater depths a pulsating, air-filled cavitation bubble would form, collapse, and reform around the detonation point (Urick, 1983). The Navy's acoustic effects model for analyzing underwater impacts on marine species does not account for the loss of energy due to surface blow-off or cavitation at depth. Both of these phenomena would diminish the magnitude of the acoustic energy received by an animal under real-world conditions (U.S. Department of the Navy, 2018c).

Propagation of explosive pressure waves in water is highly dependent on environmental characteristics such as bathymetry, bottom type, water depth, temperature, and salinity, which affect how the pressure waves are reflected, refracted, or scattered; the potential for reverberation; and interference due to multi-path propagation. In addition, absorption greatly affects the distance over which higher-frequency components of explosive broadband noise can propagate. Because of the complexity of analyzing sound propagation in the ocean environment, the Navy relies on acoustic models in its environmental analyses that consider sound source characteristics and varying ocean conditions across the PMSR Study Area (Navy, 2019a).

Missiles, rockets, bombs, and medium and large-caliber projectiles may be explosive or nonexplosive, depending on the objective of the testing or training activity in which they are used. The planned activities do not include explosive munitions used underwater. Missiles, bombs, and projectiles that detonate at or near (within 10 m (11 yd) of) the water's surface are considered for the potential impact they may have on marine mammals. All explosives used during testing and training activities within the PMSR Study Area will detonate at or near the surface or in-air. Several parameters influence the acoustic effect of an explosive: the weight of the explosive warhead, the type of explosive material, the boundaries and characteristics of the propagation medium(s); and the detonation depth underwater and the depth of the receiver (

i.e.,

marine mammal). The net explosive weight (NEW), which is the explosive power of a charge expressed as the equivalent weight of trinitrotoluene (TNT), accounts for the first two parameters.

Land-Based Launch Noise on San Nicolas Island

Noise from target and missile launches on SNI can also occur. These ongoing activities affecting pinnipeds hauled out in the vicinity of launch sites have been analyzed previously (NMFS 2014, 2019, 2020) and are summarized below as part of the Navy's rulemaking/LOA application. As part of previous authorizations, the Navy could conduct up to 40 launch events annually from SNI, but the total may be less than 40 depending on operational requirements. Launch timing will be determined by operational, meteorological, and logistical factors. Up to 10 of the 40 launches may occur at night, but this is also dependent on operational requirements, and night-time launches are only conducted when required by test objectives.

Vessel Strike

Vessel strikes have the potential to result in incidental take from serious injury and/or mortality. Vessel strikes are not specific to any particular training or testing activity, but rather are a limited, sporadic, and incidental result of Navy vessel movement within a study area.

The number of Navy vessels in the PMSR Study Area at any given time varies and is dependent on scheduled testing and training requirements. Navy vessels transit at speeds that are optimal for fuel conservation or to meet training and testing requirements. Additional detail on vessel strike was provided in our

Federal Register

notice of proposed rulemaking (86 FR 37790; July 16, 2021); please see that notice of proposed rulemaking or the Navy's application for more information. Information on Navy vessel movement in the PMSR Study Area is provided in the

Vessel Movement

section of this rule.

Detailed Description of the Specified Activities

Planned Training and Testing Activities

Training and testing activities will be conducted at sea, in designated airspace, and on SNI, within the PMSR Study Area.

The training and testing activities are deemed necessary to accomplish Naval Air Systems Command's mission of providing for the safe and secure collection of decision-quality data; and developing, operating, managing and sustaining the interoperability of the Major Range Test Facility Base at the PMSR into the foreseeable future. Collectively, the training and testing activities support current and projected military readiness requirements into the foreseeable future, as shown in Table 1.

Table 1—Maximum Number of Annual Planned Activities in the PMSR Study Area

[Inclusive of SNI launches]

Activity

Activity sub category

Planned

activities

Aerial Targets (# of targets)

176

Surface Targets (# of targets)

522

Ordnance (# of ordnance)

Bombs

30

Gun Ammunition

281,230

Missiles

584

Rockets

40

Most of the factors influencing frequency and types of activities are fluid in nature (

i.e.,

continually evolving and changing), and the annual activity level in the PMSR Study Area will continue to fluctuate. The number of events may not be the same year to year, but the maximum number of events were predicted annually. Total annual events will not exceed what is planned in Table 1 above. Training and testing duration and frequency varies depending on Fleet requirements, and funding and does not occur on a predictable annual cycle.

Fleet training activities occur over scheduled continuous and uninterrupted blocks of time, focusing on the development of core capabilities/skills. Training events in the PMSR Study Area are conducted to ensure Navy forces can sustain their training cycle requirements. Primarily, changes occur with increases or decreases in annual operational tempo of activities, in addition to changes in the types of aircraft, vessels, targets, ordnance, and tasks that are actions or processes performed as part of Navy operations.

Future testing depends on scientific and technological developments that are not easy to predict, and experimental designs may evolve with emerging science and technology. Even with these challenges, the Navy makes every effort to forecast all future testing requirements. As a result, testing requirements are driven by the need to support Fleet readiness based on emerging national security interests, and alternatives must have sufficient annual capacity to conduct the research, development, and testing of new systems and technologies, with upgrades, repairs, and maintenance of existing systems.

Fleet Training

Fleet training within the PMSR Study Area includes the same types of warfare of the primary mission areas. Training conducted in conjunction with testing activities provide Fleet operators unique opportunities to train with ship and aircraft combat weapon systems and personnel in scripted warfare environments, including live-fire events. For example, Fleet training would occur while testing a weapon system, in which Sailors would experience (be trained in) the use of the system being tested. Combat ship crews train in conjunction with scheduled ship testing and qualification trials, to take advantage of the opportunity to provide concurrent training and familiarization for ship personnel in maintaining and operating installed equipment, identifying design problems, and determining deficiencies in support elements (

e.g.,

documentation, logistics, test equipment, or training). Live and inert weapons, along with chaff, flares, jammers, and lasers may be used.

Typically concurrent with testing, surface training available within the PMSR Study Area includes tracking events, missile-firing events, gun-firing events, high-speed anti-radiation missile events, and shipboard self-defense system training, (

e.g.,

Phalanx (Close-in Weapons System), Rolling Airframe Missile, and Evolved Sea Sparrow Missile). These events are limited in scope and generally focus on one or two tasks. Missiles may be fired against subsonic, supersonic, and hypersonic targets. Certain training events designed for single ships are conducted to utilize unique targets only available for training in the PMSR Study Area.

Aviation warfare training conducted in the PMSR Study Area, categorized as unit-level training, is designed for a small number of aircraft up to a squadron of aircraft. These training events occur within the PMSR Study Area, as it is the only West Coast Navy venue to provide powered air-to-air targets. They are limited in scope and generally focus on one or two tasks. These scenarios require planning and coordination to ensure safe and effective training.

Combat Systems Testing

The System Command Program Executive Offices are tasked with conducting extensive combat systems tests and trials on each new platform prior to releasing the platform to the Fleet, to include ships that have been in an extended upgrade or overhaul status. The PMSR Study Area is the preferred site to conduct these tests, as it offers a venue for a thorough evaluation of combat and weapons system performance through the actual employment of weapon systems. The comprehensive tests are conducted by the responsible Test or Program Manager, with close cooperation from the Fleet Type Commanders (Surface Force, Air Force, or Submarine Force). Frequent tests conducted in the PMSR Study Area are Combat Systems Ship Qualification Trials (CSSQTs). This is a series of comprehensive tests and trials designed to show that the equipment and systems included in the CSSQT program meet combat system requirements. Live and inert weapons, along with chaff, flares, jammers, and lasers may be used. Naval Sea Systems Command has recently developed two new reporting programs to test and evaluate combat and weapons system performance on new classes of ships, resulting in an increased tempo in the PMSR Study Area.

Explosives At-Surface or Near the Surface

Missiles, bombs, and projectiles that detonate at or near (within 10 m (11 yd) of) the water's surface are considered for the potential that they could result in an acoustic impact to marine mammals that may be underwater and nearby. The maximum number of explosives and the appropriate events modeling bin for the planned activities are provided in Table 2. Table 2 describes the maximum number of explosives that could be used in any year under the planned training and testing activities. Under the planned activities, bin use could vary annually (but will not exceed the maximum), and the 7-year totals for the planned training and testing activities take into account that annual variability.

Table 2—Explosives Detonating at or Near the Surface by Bins Annually and for a 7-Year Period for Training and Testing Activities Within the PMSR Study Area

[Inclusive of SNI launches]

Primary mission area activity scenarios

Explosive

bin

Munition

Type

Maximum

number of

high explosive

munitions

used annually

Maximum

number of

high explosives

used over a

7-year period

planned

activity

Surface-Surface

E1

Gunnery

22,110

154,770

E3

Gunnery

4,909

34,363

E5

Gunnery

1,666

11,662

Air-Surface

E5

Rockets

24

168

Air-Surface; Surface-Air

E6

Missiles

72

504

Air-Surface

E7

Missiles, Bombs

45

315

Air-Surface; Surface-Air

E8

Missiles

45

315

Air-Surface; Surface-Surface

E9

Missiles, Bombs, Rockets

58

406

Surface-Surface; Subsurface-Surface

E10

Missiles

13

91

Note:

Bins E1-E5 are gunnery events that involve guns with high rates of firing “clusters” of munitions (

e.g.,

>80-200 rounds per minute for Bin E1, 500-650 rounds per minute for Bin E3, and 16-20 rounds per minutes for Bin E5), hence the high number of HE munitions used during these activities. The numbers above do not reflect the actual number of events, which can vary and typically last 1-3 hrs. The increase in tempo under the planned action is a result of an increase in Combat Systems Ship Qualification Trials as discussed in Section 2.2.1 (Current and Proposed Activities) of the 2021 PMSR FSEIS/OEIS.

Explosions that occur during air warfare will typically be at a sufficient altitude that a large portion of the sound refracts upward due to cooling temperatures with increased altitude. Based on an understanding of the explosive energy released by detonations in air, detonations occurring in air at altitudes greater than 10 m (11 yd) are not likely to result in acoustic impacts to marine mammals and thus are not carried forward in the analysis.

Missile Launch Activities on SNI

A combination of missiles and targets are launched from SNI, including aerial targets, surface-to-surface missiles, and surface-to-air missiles, with aerial targets representing the majority of the launches from SNI. For information on the sound levels these missiles produce please refer to Section 1.2 of the application. Under this rule, missiles launched from SNI will have sound source levels the same or lower than missiles described above or previously launched from the island.

Table 3 shows the number of launches that have occurred at SNI since 2001 and the number of launch events that have occurred during the associated comprehensive reporting timeframes. There have not been more than 25 launch events conducted in any given year since 2001. However, as part of the planned activities, 40 launch events per year from SNI involving various missiles and aerial targets are requested for take authorization.

Table 3—The Total Number of Launches That Have Occurred Since 2001 at SNI

Time period

Number of

launches

August 2001 to March 2008

77

June 2009 to June 2014

36

June 2014 to June 2019

27

Vessel Movement

The number and type of scheduled Navy vessels or Navy support vessels operating within the PMSR Study Area depends on the requirements for mission-essential activities, such as the test and evaluation of new weapon systems or qualification trials for upgraded existing ships. The types of Navy vessels or Navy support vessels operating within the PMSR are highly variable and range from small work boats used for nearshore work to major Navy combatants, up to and including aircraft carriers. Navy activities are conducted in large subdivisions of the total PMSR Study Area, and blocks of range times are allocated based on activity requirements. Most activities include either one or two vessels and may last from a few hours to 2 weeks. Vessel movement as part of the planned activities will be widely dispersed throughout the PMSR Study Area.

The PMSR Study Area military vessel activity can be divided into two categories: project ships and support boats. Project ships are larger Navy combatant vessels, such as destroyers, cruisers, or any other commissioned Navy or foreign military ship directly involved in events. They may operate anywhere within the PMSR Study Area depending on activity needs, although most ship operations occur within 60 nmi (111 km) of SNI. Most project ships and scheduled training ships operating in the PMSR Study Area transit there from off-range (

e.g.,

San Diego). Support boats are smaller vessels directly involved in test activities and operate from the Port Hueneme Harbor. While they may also operate throughout the PMSR Study Area, support boat operations occur mainly within the range areas receiving the most use. Smaller support boats have limited range and usually operate close to shore near Point Mugu and SNI. The activity level of ships or boats is characterized by a ship or boat event.

The Navy tabulated annual at-sea vessel steaming days for training and testing activities projected for the PMSR Study Area. Approximately 333 annual events of Navy at-sea vessel usage will occur over 2,085 hours (approximately 87 at-sea days) in the PMSR Study Area (Table 4). In comparison to the Southern California portion (SOCAL) of the Hawaii-Southern California Training and Testing (HSTT) Study Area, the estimated number of annual at-sea days in the PMSR Study Area is less than 3 percent of what occurs in SOCAL annually.

Table 4—Annual At-Sea Vessel Steaming Days for Training and Testing Activities Projected for the PMSR Study Area

Vessel

Ship type

Planned activity

Events

Hours

CG

Guided Missile Cruiser

41

275

DDG-51

Guided Missile Destroyer

36

132

LHA

Amphibious Assault Ship

40

200

SDTS

Self-Defense Test Ship

50

190

WMSL-751/OPC

Coast Guard Cutter

6

28

LCS Variant (LCS 1)

Littoral Combat Ship

40

360

LCS Variant (LCS 2)

40

360

FF

Future Frigate

40

360

DDG 1000 Zumwalt Class

Guided Missile Destroyer

3

30

LHD

Amphibious Assault Ship

4

13

LPD

Amphibious Transport Deck

4

13

LSD

Dock Landing Ship

4

13

CVN

Nuclear-Powered Aircraft Carrier

6

16

SSBN

Ballistic Missile Submarine

19

95

Total

333

2,085

Standard Operating Procedures

For training and testing to be effective, personnel must be able to safely use their sensors and weapon systems as they are intended to be used in military missions and combat operations and to their optimum capabilities. Because standard operating procedures are essential to safety and mission success, the Navy considers them to be part of the planned Specified Activities, and has included them in the environmental analysis (see Chapter 3 (Affected Environment and Environmental Consequences) of the 2021 PMSR FSEIS/OEIS for further details). Additional details on standard operating procedures were provided in our

Federal Register

notice of proposed rulemaking (86 FR 37790; July 16, 2021); please see that notice of proposed rulemaking or the Navy's application for more information.

Comments and Responses

We published the proposed rule in the

Federal Register

on June 16, 2021 (86 FR 37790), with a 45-day comment period. With that proposed rule, we requested public input on our analyses, our preliminary findings, and the proposed regulations, and requested that interested persons submit relevant information and comments. During the 45-day comment period, we received four comment submissions: one from the Marine Mammal Commission (Commission); one from a non-governmental organization, the Natural Resources Defense Council (NRDC); and two from private citizens. The private citizens' comments, one of which expressed general disapproval of the action, and the other of which was unrelated to this action, have been reviewed, but did not include information pertinent to NMFS' decision in this final rule, and therefore, are not addressed further.

NMFS has reviewed and considered all public comments received on the proposed rule and issuance of the LOA. All substantive comments and our responses are described below. We organize our comment responses by major categories.

Density Estimates

Pinniped Density Estimates

Comment 1:

The Commission commented that the following pinniped information was omitted in Navy documents for the PMSR Study Area, but has been previously included in other Navy environmental compliance documents as well as versions of the Navy Marine Species Density Database (NMSDD).

• Abundance(s), percentages of occurrence in the area and whether those percentages were dependent on age and sex, and percentages within the three stipulated geographic distances from shore for California sea lions. Only fall and winter densities were parsed by the three geographic distances, spring and summer were parsed by two distances (

e.g.,

see Figures 7-40 to 7-43 in Navy 2020 technical report, “Quantifying Acoustic Impacts on Marine Species: Methods and Analytical Approach for Activities at the Point Mugu Sea Range”) (hereinafter referred as the “PMSR Density Technical Report”).

• Abundance(s), percentages of the population at sea, and percentages within the two depth regimes for Guadalupe fur seals.

• Abundance and whether haulout correction factors or percentages of the population at-sea were incorporated for harbor seals, as was done for other locations (

e.g.,

Navy 2019 technical report, “U.S. Navy Marine Species Density Database Phase III for the Northwest Training and Testing Study Area”).

Response:

The Navy's application indicated in Section 6.5.2.1.4 (Marine Mammal Density) that to characterize the marine species density for large areas such as the PMSR Study Area, the Navy compiled data from several sources and the PMSR densities were in most cases consistent with the densities in the Hawaii-Southern California Training and Testing (HSTT) or Northwest Training and Testing (NWTT) Study Areas. The Navy developed a protocol to select the best available data sources for each species, distribution area, and time of year (season). The resulting Geographic Information System database, the NMSDD, includes seasonal density values for every marine mammal species present within the PMSR Study Area (U.S. Department of the Navy, 2017d, 2019a). The Navy applied these densities to the PMSR Study Area and relied on detailed explanations presented previously in the technical reports, “Navy Marine Species Density Database Phase III for the Hawaii-Southern California Training and Testing Study Area (2017)” (hereinafter “HSTT Density Technical Report”) and the “U.S. Navy Marine Species Density Database Phase III for the Northwest Training and Testing Study Area” (hereinafter “NWTT Density Technical Report”).

The Navy has provided additional details on the density derivations in this final rule in this

Comments and Responses

section to address the Commission's comments. It is important to note that the Navy is continuously updating species densities in the NMSDD based on new survey data, updated species distribution models, telemetry data, and, in the case of pinnipeds, new information on post breeding and molting distributions and haulout behavior. The availability of updated density estimates for use in the NMSDD may not coincide with the Navy's schedule for acoustic impacts modeling, which runs simultaneously for numerous projects, and can lead to differences in densities used based on timing of different projects.

California sea lions

—The densities used for the PMSR Study Area were taken from the latest density derivations presented in the NWTT Density Technical Report. The California sea lion densities in the NWTT Study Area were based on in-water abundance estimates by Lowry and Forney (2005) off the California coast. The Navy only needs in-water densities to complete acoustic effects modeling, so these data were of particular interest and relevancy. Because the abundance estimates were for sea lions occurring in the water (as opposed to at haulouts), the Navy did not need to derive an in-water abundance for the density calculation, and the other factors, such as age- and sex- specific haulout correction factors that are typically applied, were not needed. The Navy used the in-water abundance provided by Lowry and Forney (2005) to derive an in-water density. Figures 7-40 through 7-43 in the Navy 2020 PMSR Density Technical Report depicted densities for California sea lions in the PMSR Study Area used three strata defined by distance from shore (0 to 40 km (0 to 22 nmi), 40 to 70 km (22 to 38 nmi), and 0 to 450 km (0 to 243 nmi)). The third stratum was included as an attempt to account for a wider distribution of sea lions documented during El Niño conditions. For the two figures appearing to have only 2 strata (Figures 7-40 and 7-43), the density ranges shown in the legends span two of the three uniform density estimates, making it appear as if there are only two strata. In Figure 7-40 of the Navy's 2020 PMSR Density Technical Report, the two strata, 40 to 70 km (22 to 38 nmi) and 0 to 450 km (0 to 243 nmi), had densities that fall within the range 0.0037-0.0065 sea lions/km

2

and therefore used one color. A similar overlap in densities occurs in Figure 7-43, except that in this figure the first two strata (0 to 40 km (0 to 22 nmi) and 40 to 70 km (22 to 38 nmi)) represent densities in the same density range shown in the legend and therefore are the same color on the map.

The following description of the density derivation for California sea lions is taken from the NWTT Study Area Technical Report (Navy 2020).

Seasonal at-sea abundance is estimated from strip transect survey data collected offshore along the California coastline (Lowry and Forney, 2005). The survey area was divided into 7 strata, labeled A through G. Abundance estimates from the two northernmost strata (A and B, note this refers to a different area/set of strata than are addressed in the paragraph above) were used to estimate the abundance of California sea lions occurring in the [NWTT] Study Area. While the northernmost stratum (A) only partially overlaps with the [NWTT] Study Area, this approach conservatively assumes that all sea lions from the two strata would continue north into the Study Area . . . The abundance estimates used in this report, based on Lowry and Forney (2005), were: 2,822 sea lions in fall, 3,977 in spring, and 3,288 in winter. An estimate of 3,000 male sea lions is used for the month of August. Projected 2017 seasonal abundance estimates were derived by applying an annual growth rate of 5.4 percent (Carretta

et al.

2017) between 1999 and 2017 to the abundance estimates from Lowry and Forney (2005). No correction for hauled-out sea lions was needed because counts were of sea lions in the water (Lowry and Forney, 2005).

The strata used to calculate densities were based on distribution data from Wright

et al.

(2010) and Lowry and Forney (2005) indicating that approximately 90 percent of California sea lions occurred within 40 km (22 nmi) of shore and 100 percent of sea lions were within 70 km (38 nmi) of shore. The offshore distribution is consistent with survey data reported by Oleson

et al.

(2009) and migration patterns observed by Gearin

et al.

(2017), which showed that males remained within the 1,000 m (1,094 yd) isobath as they migrated between Puget Sound and the Channel Islands. Sea lions tagged in Puget Sound and tracked as they traveled along the U.S. West Coast were within a mean distance of 14 nmi (26 km) from shore (DeLong

et al.

2017). A third stratum was added that extends from shore to 450 km (243 nmi) offshore to account for anomalous conditions, such as changes in sea surface temperature and upwelling associated with El Niño, during which California sea lions have been encountered farther from shore, presumable seeking prey (DeLong and Jeffries, 2017; Weise

et al.

2010). Sample density calculations are provided below.

Fall Density = (7,273 sea lions × 0.90)/11,744 km

2

= 0.5573 sea lions/km

2

(0 to 40 km Stratum)

Spring Density = (10,249 sea lions × 0.10)/791 km

2

= 1.2951 sea lions/km

2

(40 to 70 km Stratum)

Winter Density = (8,473 sea lions × 1.00)/143,518 km

2

= 0.0590 sea lions/km

2

(0 to 450 km Stratum)

August Density = 3,000 sea lions/93,747 km

2

= 0.0288 sea lions/km

2

(0 to 40 km Stratum)

Densities in the NWTT Density Technical Report were the most recently calculated densities for California sea lion and were used instead of densities calculated for the HSTT Density Technical Report (U.S. Department of the Navy, 2017).

Guadalupe fur seals

—A more detailed description of the density derivation for Guadalupe fur seal was missing from the PMSR Density Technical Report, but is provided here. Densities for Guadalupe fur seals were derived for both the HSTT Study Area and later for the NWTT Study Area. However, following completion of acoustic impact modeling for the HSTT EIS/OEIS, new data became available on the abundance and distribution of Guadalupe fur seals in southern California. These data showed that the fur seals were distributed farther offshore than presented in the HSTT Density Technical Report. Densities for Guadalupe fur seal off California were revised for use in subsequent projects, including the 2022 PMSR EIS/OEIS, as noted in a footnote in the HSTT Density Technical Report. A description of the derivation of the updated densities for Guadalupe fur seal was prepared but was not appended to the HSTT Density Technical Report and was not otherwise available to the public. The same data prompting the revised densities for the HSTT Study Area were used in deriving densities for Guadalupe fur seals in the NWTT Study Area, and a detailed explanation of how the data were used in the NWTT Study Area is described in the NWTT Density Technical Report. However, it would not be possible to derive the revised HSTT densities, later applied to the PMSR Study Area, from information in the NWTT Density Technical Report. Therefore, a description of the revised HSTT density derivation for Guadalupe fur seal is provided below. These densities were used for the PMSR Study Area acoustic analysis and are shown in the PMSR Density Technical Report.

To determine the density of Guadalupe fur seals in the Southern California area, the entire population (33,485 fur seals) was divided by the area of the NMFS Southern California Stratum seaward of the 3,000 m (3,281 yd) isobath. The Southern California portion of the HSTT Study Area extends to just north of Isla Guadalupe, so a majority of the range of the Guadalupe fur seal overlaps with the offshore

portion of the SOCAL Range Complex. Guadalupe fur seals are expected to occur year-round in the Southern California portion of the HSTT Study Area, with abundance in the region varying seasonally and by life stage (Norris, 2017). In summer (June-August), adult males are expected to be hauled-out on Guadalupe Island south of the HSTT Study Area. Adult females would also be expected to be on or in the vicinity of Guadalupe Island in summer and south of the Study Area. Satellite-tagged juveniles and weaned pups (<2 years old) have been shown to migrate north after the breeding season through the Southern California portion of the HSTT Study Area and to areas north of the Study Area and remain there from June through November (

i.e.,

summer and fall) (Norris 2017).

Seasonal densities were calculated by estimating the percentage of the population occurring at sea in HSTT the Study Area for each season. For all life stages combined, approximately 73 percent of the population is expected to be in the HSTT Study Area in winter and spring (non-breeding season) and approximately 33 percent of the population is expected to be in the HSTT Study Area in summer and fall, encompassing the breeding season (Norris 2017). Spatially, two thirds of the Guadalupe fur seal population (66.7 percent) would be expected in the Baja stratum and one third (33.3 percent) would be expected in the SOCAL stratum during the year. Furthermore, while at sea, healthy Guadalupe fur seals are not expected to haul out. Sick or stranded fur seals may be sighted along the coast or on offshore islands during the non-breeding season, however, these cases are not representative of the population at sea. Therefore, no adjustment to account for hauled-out fur seals is needed.

Densities are calculated by estimating the number of fur seals in the two strata during winter/spring and summer/fall. The spatial area for the SOCAL stratum is approximately 66,058 km

2

(19,259 nmi

2

) and the spatial area for the Baja stratum is approximately 152,889 km

2

(44,575 nmi

2

).

SOCAL Offshore (>3,000 m (3,281 yd) isobath)

Winter/Spring:

(33,485 × 0.73) × 0.333/66,058 km

2

= 0.1232 fur seals/km

2

Summer/Fall:

(33,485 × 0.33) × 0.333/66,058 km

2

= 0.0557 fur seals/km

2

Extrapolating these densities into the PMSR likely overestimated occurrence in the PMSR Study Area, because Guadalupe fur seals are more prevalent farther south off southern California and Baja California, Mexico where breeding colonies are located.

Harbor seals

—A density estimate for PMSR Study Area was extrapolated from the NWTT Study Area. As described below, an in-water abundance was calculated using published haulout correction factors and used to estimate an annual density. The following description from the NWTT Density Technical Report is provided.

An estimate of 30,968 harbor seals make up the California stock (Carretta

et al.

2017). As with the Washington and Oregon Coast stock, growth is assumed to be flat (Carretta

et al.

2017; DeLong and Jeffries, 2017). Based on surveys in 2002 and 2004, Lowry

et al.

(2008) estimated that 37.8 percent of harbor seals in the California stock are in northern California, defined as the area from Point Reyes to the California/Oregon border (

i.e.,

the coastline from 38.00 N to 42.000° N). Harbor seals in northern California are expected to be in the water 36 percent of the time (Harvey and Goley, 2011), and a single stratum extending 30 km (16 nmi) from shore between 38.00 N to 42.000° N along the California coastline was used to define the spatial area.

Density = (30,968 × 0.378) × 0.36/15,496 km

2

= 0.2719 seals/km

2

As shown in the PMSR Density Technical Report (Navy 2020), the Navy used an annual harbor seal density of 0.2719 areas within 50 miles around all known haulout sites within the PMSR Study Area. Zero density was used beyond 50 miles from shore.

Comment 2:

The Commission also comments that the area metrics necessary to derive the density estimates were omitted by the Navy's 2020 PMSR Density Technical Report. Since the densities were exactly the same for elephant seals and northern fur seals in that report as had been used previously for the HSTT Study Area in the HSTT Density Technical Report (Navy 2017), the same presumed occurrence areas had to have been used. For northern fur seals, the area used was based on the NMFS SOCAL stratum for its vessel-based surveys (

i.e.,

Barlow 2010); while for elephant seals, the area was based on the Navy SOCAL modeling area (Department of the Navy 2017c). None of the underlying abundance data that were provided in the reports above are related to either of those areas. As such, it is unclear why the Navy felt it necessary to use two different areas, when neither of them relates to the abundance data. Both areas are similar in extent, with the Navy SOCAL modeling area being approximately 13 percent larger than the NMFS SOCAL stratum.

Response:

As noted in the comment, the densities for northern fur seal and northern elephant seal used for the PMSR acoustic analysis were extrapolated from the HSTT Study Area, and the derivations of those densities were described in detail in the HSTT Density Technical Report. The northern fur seal density calculation used the NMFS SOCAL Bight stratum (318,541 km

2

; 92,872 nmi

2

) to represent fur seal distribution and the northern elephant seal density calculation used the Navy SOCAL modeling area stratum (361,872 km

2

) to represent northern elephant seal distribution. While there is not a substantial difference between the sizes of the two areas (as pointed out in the comment), and both areas were used in the pinniped density estimates for these and other species, the smaller NMFS SOCAL Bight Stratum was used for the northern fur seal calculation, because most northern fur seals were expected to move north of San Miguel Island after the breeding season and would not be distributed over as wide an area as elephant seals off California. Northern elephant seals in the California stock also migrate north of the Channel Islands after breeding and molting periods, and elephant seals from the Mexico population are known to migrate into SOCAL from the south. Elephant seals would be distributed over a larger area off California and farther offshore, so the larger of the two strata, the Navy SOCAL Modeling Stratum, was used for elephant seals.

At the time that HSTT Phase III densities were calculated, the Navy sought to estimate densities in pre-defined strata to focus where densities were needed for modeling acoustic impacts. The practice was relevant to creating models of cetacean densities, which were based on repeated surveys of the California Current Ecosystem (CCE) and other well defined areas; however, published descriptions of pinniped abundances and distributions were based mainly on seals and sea lions at haulout sites with some complimentary telemetry data, and less often on line transect surveys at sea. Beginning with the NWTT EIS/OEIS, the Navy moved away from using pre-defined strata for pinnipeds and relied more on published data describing distributions based on depth, distance from shore, and other habitat preferences as well as telemetry data to define pinniped strata.

Comment 3:

The Commission comments that for the other three pinniped species (harbor seal, California sea lion, and Guadalupe fur seal), some of the densities provided in the Navy 2020 PMSR Density Technical Report differ by orders of magnitude from those provided in the Navy's technical report, HSTT Density Technical Report (Navy

2017), even though some of the same data appear to have been used and are based on some of the same geographic areas. The Commission said that the Navy stated that, although the density estimates may not be accurate given interannual variability and fluctuations in population size or may not exactly reflect spatial distributions, they represent the best available science due to the paucity of other data and are considered to be the most conservative in the technical report Navy 2020 PMSR Density Technical Report. The Commission further claims it is unclear how such a statement can be evaluated when the underlying data were not provided for public review and comment. As such, the Commission recommends that, prior to issuing any final rule, NMFS provide information regarding the data and assumptions used to inform the pinniped density estimates and allow for additional public review and comment on that information.

Response:

NMFS has provided additional detail regarding how the densities for PMSR were calculated and the underlying assumptions in the response to Comment 1. The Navy maintains the Navy Marine Species Density Database (NMSDD), which uses standard protocols to support spatially explicit density estimates for all of the Navy training and testing rules. The Navy develops NMSDD reports for all major training regions (

e.g.,

HSTT and NWTT) and the reports detail the standard methods used across all areas and specify the results for the given region/Study Area. The HSTT and NWTT NMSDD reports have been provided for public review and comment through the National Environmental Policy Act (NEPA) (draft EIS) and MMPA (proposed rule) compliance documentation associated with the Navy's NWTT and HSTT actions over the last few years. The Point Mugu proposed rule included an overview of the methods used for estimating density in the PMSR, and referenced the more detailed NMSDD report for HSTT, which NMFS considered sufficient to support the necessary determinations. As further described below, while the proposed rule referenced the HSTT NMSDD report in supporting the PMSR density estimates, in some cases the more up-to-date estimates from the NWTT NMSDD report were actually used to support the NMSDD estimate for PMSR. While this inadvertently omitted reference to the NWTT report created some confusion, the density estimates presented in the proposed rule were correct, the general methodology was available for public review, and our findings remain the same. Below we include additional information to address the Commission's comment regarding the densities differing by order of magnitude.

New densities were derived for the NWTT Study Area using an improved approach, and those densities were used for PMSR Study Area instead of the older HSTT densities that the Commission is making comparisons to. As the Commission points out, the new densities were in some cases orders of magnitude greater than the older HSTT densities. The increases were due to several factors. The main factors were (1) the calculation of more refined in-water abundance estimates using species-specific and seasonal haulout factors for example, and (2) smaller and more representative areas of occurrence over which the in-water abundance estimates were distributed to calculate the densities. Generally, smaller distribution areas translate to higher densities when the abundance estimates are about the same.

For example, for harbor seals, the highest HSTT density was 0.0183. The highest density for the NWTT Study Area, which was 0.2719, was the density used for the PMSR Study Area. The HSTT density was based on an abundance of 6,813 seals in southern California, approximately 22 percent of the population. The NWTT density assumed 37.8 percent of seals occurred in northern California for an abundance of 11,706 seals. So, one factor contributing to an increase in density is an increase in abundance. For the HSTT Study Area, we used the Southern California stratum to be consistent with strata used for cetacean densities, but, in retrospect, this was an overestimation (and oversimplification) of where harbor seals would most likely occur. For the NWTT Study Area, we used a distribution area along the coastline extending from shore to 30 km (16 nmi) offshore, which is considerably smaller than the Southern California stratum and a better representation of the typical distribution of harbor seals. Since harbor seals are more common farther north, off central and northern CA where approximately 88 percent of the population occurs, it was more appropriate to use the NWTT density instead of the HSTT density for PMSR Study Area.

For California sea lions, the highest HSTT density was 0.0596 (excluding San Diego Bay and Silver Strand). The highest density in NWTT was 1.49. Similar to the approach used in HSTT for harbor seals, the in-water abundance from Lowry and Forney (2005) was distributed over the expansive SOCAL Modeling Area to ensure a density was provided in all areas where modeling was needed. In contrast, for the NWTT Study Area, the distribution area was based more on California sea lion's preferred habitat, which was divided into three strata based on distance from shore, resulting in a more realistic range that better represented where the sea lions predominantly occur. This resulted in a smaller distribution area and a larger density. The details of these calculations are provided in the NWTT Density Technical Report.

For Guadalupe fur seal, the source data on abundance and distribution changed based on new research available after the HSTT densities were finalized, as explained in Comment 1. A comparison with the older HSTT densities published in the HSTT Density Technical Report is not relevant.

Comment 4:

The Commission commented that it had previously provided extensive comments regarding the manner in and the data upon which the Navy had derived its pinniped density estimates, including for the densities that were used by the Navy for the HSTT Study Area, as provided in Navy (2017c; see the Commission's 13 July 2018 letter). The Commission comments that both NMFS and the Navy failed to recognize that the original abundance estimate that they had used of 18,430 elephant seals from Lowry (2002) was based on elephant seal counts from only Santa Barbara Island (SBI), San Clemente Island (SCI), and SNI (Navy 2017c). Navy (2017c) specified that large rookeries also occur on San Miguel Island (SMI) and Santa Rosa Island (SRI), but both islands are located at least 55 km (30 nmi) north of the HSTT Study Area and thus were not included. That may be appropriate for the HSTT Study Area, but SMI and SRI are both well within the PMSR Study Area. A total of 37,294 elephant seals were sighted at SBI, SNI, SMI, and SRI in 2001 (Lowry 2002), which is greater than the 36,646 seals that NMFS estimated would occur in the PMSR Study Area presently. If the relevant abundance estimates had been forward-projected using the applicable 3.8-percent growth rate into 2021, the California population estimate would be 81,618 elephant seals. Added to the Mexico population estimate, 112,618 seals would be expected to occur in the PMSR Study Area rather than the 36,646 seals used to inform the density estimate for the proposed rule. An underestimation by a factor of more than three is not considered

insignificant. Moreover, NMFS cannot deem one growth rate best available science for incidental taking purposes and another best available science for its Stock Assessment Reports (SARs), particularly since NMFS used the same overall stock abundance for both purposes (Tables 5, 31, and 32 in the proposed rule). At a minimum and until additional data are provided for the other pinniped species and additional assumptions are provided for elephant seals, the Commission recommends that NMFS (1) re-estimate the density for elephant seals based on (a) the 2001 abundance of 37,294 elephant seals from SBI, SNI, SMI, and SRI (Lowry 2002) forward-projected to 2021 using the 3.8-percent growth rate from Lowry

et al.

(2014) for the California population, and (b) at least 31,000 seals from Lowry

et al.

(2014) as representative of the Mexico population; and (2) then re-estimate the numbers of takes accordingly in the final rule.

Response:

This Commission is correct that San Miguel Island (SMI) and Santa Rosa Island (SRI) are in PMSR Study Area and inhabited by elephant seals during molting and breeding periods. However, elephant seals travel north and west of the PMSR Study Area (post breeding/molting) as far as the Gulf of Alaska and the central North Pacific (

e.g.,

Robinson

et al.

2012), and the density estimated for the PMSR Study Area assumed a large percentage of elephant seals remained in the PMSR Study Area year round. This conservative assumption overestimates the abundance in the PMSR year round and, while not ideal, essentially offsets the lack of abundance data from SMI and SRI that were left out of the density calculations for the PMSR Study Area. Furthermore, when breeding and molting in California, elephant seals are mainly hauled out or near haulout sites, with the exception of short foraging bouts by lactating females. Therefore, time in the water, particularly from shore, while in the PMSR Study Area is less than assumed in the density estimate, further reducing the probability of exposures.

A growth rate of 1.7 percent was applied to the abundance estimate for elephant seals in southern California, as described in the HSTT Density Technical Report. The growth rate was not used to predict future, unpredictable changes in species' abundance (

i.e.,

“forward project”), but rather to estimate changes in abundance from the most recent survey date to the present time. That is, the Navy only brought the abundance from the date of the latest survey up to the time of the analysis by applying a published annual growth rate to some species' abundances. If an abundance was based on a 10 year old survey, then the Navy used the growth rate to calculate an estimated abundance for “the present time.” The reasoning for this approach is abundance for some species has been impacted by UMEs or El Nino events or higher recruitment years since the most recent surveys were conducted, and in some cases it may be reasonable to assume a growth rate accounts for those factors and can be used to estimate a present day abundance. The analysis is not attempting to forecast abundances or predict future changes due to UMEs or climate change,

etc.,

rather it is attempting to update an older abundance where appropriate, to better represent species' density at the time of analysis. The MMC commented that different growth rates were used in the calculation of elephant seal abundance. The discussion in the HSTT Density Technical Report (Section 11.1.3) reviews two approaches to estimating the abundance: (1) using island-specific abundances from the three islands (SBI, SNI, and SCI) from Lowry (2002) and a 1.7 percent growth rate, and (2) using the 2010 pup count and a multiplier from Lowry

et al.

(2014) and a 1.1 percent growth rate. The 1.1 percent growth rate is the average growth rate of populations on the three islands (SBI, SNI, and SCI) (Lowry

et al.

2014). The growth rate of 3.8 percent reported in the 2014 SAR (Carretta

et al.

2015) is for the entire population. Given their migratory behavior, which differs by sex and lifestage, it is not realistic to assume that 112,618 elephant seals would be in the PMSR Study Area at any time. While not relevant to the PMSR density, the Navy notes that in the most recent version of the SAR (Carretta

et al.

2021) NMFS has revised the annual growth rate for the population down to 3.1 percent, further illustrating the variability and level of imprecision in estimating abundances and densities, particularly when attempting to project changes. The MMC recommended estimating the Mexico population of elephant seals at 31,000 seals. The Navy also considers this to be an overestimation based on studies by Elorriaga-Verplancken

et al.

(2015) and Garcia-Aguilar

et al.

(2018) indicating the population is in decline. Garcia-Aguilar

et al.

(2018) cite a 2009 abundance of 22,000 seals. Applying the −3.2 percent annual growth rate from Elorriaga-Verplancken

et al.

(2015) to the 2009 population estimate reduces that population to approximately 18,000 seals in 2015 (time of analysis). Most of the seals would only transit through the HSTT Study Area, limiting their time in the HSTT Study Area and potential for exposure to acoustic stressors, as explained in the HSTT Density Technical Report. Based on these factors, an abundance estimate of 15,083 seals occurring in the HSTT Study Area is a reasonable and conservative estimate.

NMFS has reviewed the additional information provided by the Navy, and agrees that the information has been applied appropriately to develop density and population numbers.

Comment 5:

The Commission states that pinniped densities must be refined for the Navy's Phase IV compliance documents. The Commission recommends that NMFS consult with the Navy and experts in academia and at its own Science Centers to develop more refined pinniped density estimates that account for pinniped movements, distribution, at-sea correction factors, and density gradients associated with proximity to haulout sites or rookeries.

Response:

For future Navy Phase IV compliance documents (

e.g.,

EISs), the Navy explained that it did and will continue to consult with authors of the papers relevant to the analyses as well as other experts in academia and at the NMFS Science Centers during the development of the Navy's analyses. During the development of the HSTT and NWTT Density Technical Reports, which supplied densities for the PMSR analysis, the Navy had ongoing communications with various subject matter experts and specifically discussed pinniped movements, the distribution of populations within the study areas to support the analyses, the pinniped haulout or at-sea correction factors, and the appropriateness of density gradients associated with proximity to haulout sites or rookeries. As shown in the references cited, the personal communications with researchers have been made part of the public record, although many other informal discussions with colleagues have also assisted in the Navy's approach to the analyses presented. Moving forward in Phase IV, the Navy has continued to engage with pinniped experts to improve the representation of species' occurrence and distribution by calculating monthly densities as appropriate for each species and basing distribution areas on habitat preferences and region specific haul out behavior. Revised and updated densities for the California coast will also apply to the PMSR Study Area which is being reanalyzed as part of the new Hawaii-California Study Area (HCTT) EIS/OEIS project.

Cetacean Density Estimates

Comment 6:

The Commission comments that similar to the pinniped densities, the Navy did not specify the underlying data and assumptions used to estimate most of its cetacean density estimates for the PMSR NMSDD in the technical report, “Quantifying Acoustic Impacts on Marine Species: Methods and Analytical Approach for Activities at the Point Mugu Sea Range” (Navy 2020). The lack of transparency does not afford either the Commission or the public an opportunity to provide informed comments. Further, many of the densities in the same geographic areas differ by an order of magnitude or more from those provided in the technical report, “U.S. Navy Marine Species Density Database Phase III for the Hawaii-Southern California Training and Testing Study Area Navy” (Navy 2017) and/or Becker

et al.

(2020), which included updated models of some of the densities that were provided in “U.S. Navy Marine Species Density Database Phase III for the Hawaii-Southern California Training and Testing Study Area Navy” (Navy 2017). The Commission understands that densities provided by Becker

et al.

(2020) are considered best available science, and it is unclear why those were not used for the PMSR Study Area. Therefore, the Commission recommends that, prior to issuing any final rule, NMFS provide information regarding the data and assumptions used to inform the cetacean density estimates, allow for additional public review and comment on that information, and, if Becker

et al.

(2020) was not used to inform those estimates, explain why.

Response:

At the time that the Navy's acoustic modeling and analysis was conducted Becket

et al.

2020 was not available. The Navy did consult with E. Becker to ensure consistency with the information in the paper that was published in 2020.

For the HSTT Phase III analysis, the HSTT Density Technical Report (cited as Navy 2017c in the MMC comment above), density estimates from Becker

et al.

(2016; “Moving Towards Dynamic Ocean Management: How Well Do Modeled Ocean Products Predict Species Distributions?”, Remote Sensing, 8, 149) were used; these estimates were based on distribution models (SDMs) developed from line-transect survey data collected within the Southwest Fisheries Science Center (SWFSC) CCE study area from 1991-2009. Subsequently, for the NWTT Phase III analysis, the NWTT Density Technical Report (Navy 2019), updated density estimates were available, and these were based on line-transect survey data collected within the CCE study area during summer and fall from 1991-2014. Since the updated models included the 2014 anomalously warm year, a greater range of habitat conditions was available to parameterize the SDMs, and they were developed using improved modeling methods. Multi-year (1991-2014) average density surfaces from these SDMs were developed for 13 cetacean species and one small beaked whale guild (the guild includes Cuvier's beaked whale and species from the genus

Mesoplodon

), and were provided to the Navy for the NWTT Phase III analysis. A subset of these models was subsequently published in 2020 (Becker

et al.

2020, “Performance evaluation of cetacean species distribution models developed using generalized additive models and boosted regression trees”, Ecology and Evolution, 10, 5759-5784). Density estimates from both these sources were available at the time the Navy was identifying data to use for the PMSR analysis.

The Commission references the most recent SDMs built with 1991-2018 data, as presented in Becker

et al.

(2020; “Habitat-based density estimates for cetaceans in the California Current Ecosystem based on 1991-2018 survey data”, U.S. Department of Commerce, NOAA Technical Memorandum NMFS-SWFSC-638), hereafter “Becker

et al.

2020 TM” to differentiate from the 2020 Ecology and Evolution manuscript mentioned above. The SDMs presented in the Becker

et al.

2020 TM represent an improvement over the previous models because they included additional sighting data collected over the continental shelf and slope that were surveyed more sparsely in previous years, they better accounted for population changes in the CCE study area over the 1991-2018 survey period, and they more accurately accounted for uncertainty than prior iterations owing to methodological improvements. In addition, to ensure that the multi-year average density surfaces reflect more recent conditions and were based on those survey years that more comprehensively covered the study area, predictions for 1991, 1993, and 2009 were not included in the multi-year average. The multi-year average density surfaces derived from these models are thus based on predictions for summer/fall 1996-2018. Furthermore, for two species with documented population increases in the study area (

i.e.,

fin whale and humpback whale), the year covariate was set to 2018 to decrease the potential for biased-low density estimates derived from the multi-year average surfaces. Density estimates from the Becker

et al.

2020 TM SDMs were not available at the time the Navy was identifying the best estimates to use for the PMSR analysis. As noted above, this manuscript was subsequently published in Ecology and Evolution in 2020, and was based on SDMs developed with the 1991-2014 SWFSC survey data.

Regarding the Commission's comment that “many of the densities in the same geographic areas differ by an order of magnitude or more from those provided in Department of the Navy (2017c) and/or Becker

et al.

(2020)”—it is difficult to respond to this comment without more information on which species estimates the Commission is referring to. Also, since the estimates from Becker

et al.

models are spatially-explicit, it is unclear if the Commission is comparing specific pixel values, or looking at the highest density ranges on the PMSR maps and comparing them to the density plots included in the Becker

et al.

2020 TM, in which case the difference in the highest density range can be due to just a few high pixel values and/or the density ranges selected for presentation purposes. Comparisons are also challenging since the Becker

et al.

TM presents density surfaces for the entire CCE study area while the PMSR density plots are specific to that study area, and thus appear more pixelated given the finer spatial resolution. To help address this comment, the density estimates provided in the PMSR Density Technical Report were compared to those presented in the Becker

et al.

2020 TM. The latter presents density estimates for 14 cetacean species and the small beaked whale guild for summer/fall. The comparison was thus based on these species and seasons. For their 5-7 year environmental planning analysis, the Navy incorporates the multi-year average density plots into the Navy Marine Species Density Database (NMSDD) and uses these for their acoustic analyses. Therefore, the comparison was based on these density surfaces (vs. yearly plots), although the yearly predictions for the three large whale species were also compared to see if any substantial differences were apparent.

Below is a brief summary that compares the density values and distribution patterns presented in the PMSR Density Technical Report with those presented in the Becker

et al.

2020 TM. Note that all density values are presented in number of animals per square km (anis/km

2

), or as abundance

estimates (number of whales/dolphins occurring in a defined study area).

Blue whale.

The data source is cited as “Becker

et al.

in prep.” so the density estimates used for the PMSR analysis were the multi-year average predictions from the SDMs built with 1991-2014 survey data, while the multi-year average density surfaces presented in Becker

et al.

(2020 TM) were based on predictions from 1996-2018. The blue whale density plot presented in the PMSR Study Area has the highest density value (0.0091) as compared to the density plot included in the Becker

et al.

2020 TM with the highest value (0.0117), and predicted distribution patterns from the two models within the PMSR Study Area are similar. Although not presented in the 2020 Ecology and Evolution paper, Table 5 compares the yearly CCE study area abundance estimates derived from the SDMs built with 1991-2014 data (left) with those presented in Becker

et al.

(2020 TM) built with 1991-2018 data on the right, and provides the 95 percent confidence intervals (presented for overlapping years). As shown below, all of the abundance estimates derived from the model used for the PMSR analysis fall within the confidence limits of the SDMs presented in Becker

et al.

(2020 TM).

Table 5—Blue Whale SDM and Becker

et al.

(2020) Abundance Estimates

Year

Abundance

(1991-2014 SDMs)

Abundance

(Becker

et al.

2020 TM)

Log-normal 95 percent Cis

(Becker

et al.

2020 TM)

1996

1,901

1,946

945

4,009

2001

1,720

1,657

868

3,162

2005

1,201

1,042

542

2,004

2008

1,081

919

445

1,899

2014

1,574

1,077

495

2,342

As noted above, the Navy used the multi-year averages in their analyses, so the data used in the PMSR analysis reflect the 1991-2014 average, while the Becker

et al.

(2020 TM) data reflect the 1996-2018 average. For blue whale, the CCE study area point estimate for 2018 was the lowest yet (670 whales), resulting in a slightly lower point estimate for the 1996-2018 multi-year average density surface (1,219 whales) than the 1991-2014 average density surface (1,572 whales); density estimates within the PMSR are similar for both sets of predictions. NMFS concurs with this analysis and confirms it does not change our analysis or findings for blue whales.

Fin whale.

A source was not provided in the PMSR document for the density data used for fin whale but based on the density figure in the PMSR Density Technical Report, it was the multi-year average density surface from the SDM built with 1991-2014 data (

i.e.,

the model presented in the Becker

et al.

2020 Ecology and Evolution paper). The fin whale density plot for the PMSR Study Area had the highest density value (0.0310) as compared to the density plot included in the Becker

et al.

2020 TM with the highest density value (0.0821). Predicted distribution patterns from the two models within the PMSR Study Area are similar. Although not presented in the 2020 Ecology and Evolution paper, Table 6 compares the CCE study area abundance estimates derived from the SDMs built with 1991-2014 data (left), with those presented in Becker

et al.

(2020 TM) on the right. The estimates are so similar that the 95 percent confidence intervals are not presented below, but they are presented in Becker

et al.

(2020 TM). Therefore, yearly predictions from the two models are similar for those years that overlap.

Table 6—Fin Whale SDM and Becker

et al.

(2020) Abundance Estimates

Year

Abundance

(1991-2014 SDMs)

Abundance

(Becker

et al.

2020 TM)

1996

3,358

3,804

2001

5,753

5,733

2005

7,533

7,319

2008

7,668

7,606

2014

10,504

10,139

As noted above, the Navy used the multi-year averages in their analysis, so the data used in the PMSR analysis reflect the 1991-2014 average while the Becker

et al.

(2020 TM) data reflect the 1996-2018 average. For fin whale, this created a notable increase in the latter since the point estimate for 2018 was the highest yet (11,065 whales), and, given documented population increases in the study area, the year covariate was set to 2018 to decrease the potential for biased-low density estimates derived from the multi-year average surfaces. Therefore, the fin whale density surface used in the PMSR analysis is likely biased-low to some extent, but as noted above, the updated Becker

et al.

(2020 TM) estimates were not available at the time the Navy was identifying density data for the PMSR analysis. NMFS concurs with this analysis and confirms it does not change our analysis or findings for fin whales.

Humpback whale.

A source was not provided in the PMSR document for the density data used for humpback whale, but, based on the density figure, it was the multi-year average density surface from the SDM built with 1991-2014 data (

i.e.,

the model presented in the Becker

et al.

2020 Ecology and Evolution paper). The humpback whale density plot presented in Hulton

et al.

(2020) for the PMSR study area had the highest density value (0.0479) as compared to the density plot included in the Becker

et al.

2020 TM with the highest density value (0.194), so this is a case where the highest values do differ by an order of magnitude, although highest densities mainly occur north of

Point Conception and outside the PMSR Study Area. Although not presented in the 2020 Ecology and Evolution paper, Table 7 compares the CCE study area abundance estimates derived from the SDMs built with 1991-2014 data (left) with those presented in Becker

et al.

(2020 TM) on the right. The estimates are so similar that the 95 percent confidence intervals are not presented below, but they are presented in Becker

et al.

(2020 TM).

Table 7—Humpback Whale SDM and Becker

et al.

(2020) Abundance Estimates

Year

Abundance

(1991-2014 SDMs)

Abundance

(Becker

et al.

2020 TM)

1996

1,267

1,181

2001

1,361

1,364

2005

1,454

1,575

2008

1,638

1,727

2014

3,162

2,178

As noted above for fin whale, exclusion of the early years (1991 and 1993) and accounting for the documented increase in humpback whale abundance in the study area over the survey period when deriving the multi-year average density surfaces resulted in higher densities for the more recent 1996-2018 multi-year average. Also, the point estimate for 2018 was the highest yet (4,784 whales). Therefore, the humpback whale density surface used in the PMSR analysis is likely biased-low to some extent, but, as noted above, the updated Becker

et al.

(2020 TM) estimates were not available at the time the Navy was identifying density data for the PMSR analysis. NMFS concurs with this analysis and confirms it does not change our analysis or findings for humpback whales.

Minke whale.

Since the new minke whale SDM developed in Becker

et al.

(2020 TM) was not available at the time the Navy was identifying density data for the PMSR Study Area, the Navy used a uniform density estimate of 0.000737. (The estimate came from Barlow 2016, Table 7, and is an average of the Southern and Central CA strata estimates.)

Baird's beaked whale.

The HSTT Density Technical Report (Navy 2017) was erroneously cited as the source of the Baird's beaked whale density surface in the PMSR Density Technical Report, when in fact, the plot is consistent with the multi-year average density plot developed using 1991-2014 survey data as described in Becker

et al.

2020 (the 2020 Ecology and Evolution paper). Predicted distribution patterns from this and the Becker

et al.

(2020 TM) SDM for Baird's beaked whale are very similar, and although the highest density value on the PMSR plot is 0.0072 and on the Becker

et al.

(2020 TM) plot it is 0.0932, the top density RANGES overlap (

i.e.,

0.0048-0.0072 vs. 0.0032-0.0932, respectively); this is a case where there were a few high pixel values in northern waters of the CCE study area and outside the PMSR Study Area, thus increasing the highest value of the density range in the Becker

et al.

2020 TM plot. Density values within the PMSR Study Area are similar. NMFS concurs with this analysis and confirms it does not change our analysis or findings for Baird's beaked whales.

Small beaked whale guild (Cuvier's beaked whale and species in the genus Mesoplodon).

The HSTT Density Technical Report (Navy 2017) was erroneously cited as the source of the density surface for the small beaked whale guild in the PMSR Density Technical Report, but the plot is consistent with the multi-year average density plot developed using 1991-2014 survey data as described in Becker

et al.

2020 (the 2020 Ecology and Evolution paper). Higher density values are included in the 1991-2014 average density surface used for the PMSR analysis as compared to the Becker

et al.

(2020 TM) average density surface, and the distribution pattern in the former better matches the SWFSC sighting data. As noted in Becker

et al.

(2020 TM), the small beaked whale guild SDM had some of the worst model metrics among all species and predicted distribution patterns matched poorly to actual sightings during the surveys, so the density data used for the PMSR Study Area analysis are more appropriate than the more recent model for this group of species. NMFS concurs with this analysis and confirms it does not change our analysis or findings for the small beaked whale guild.

Bottlenose dolphin (offshore stock).

Becker

et al.

(2016) was erroneously cited as the source of the density surface for the offshore stock of common bottlenose dolphin in the PMSR Density Technical Report, but the plot is consistent with the multi-year average density plot developed using 1991-2014 survey data as described in Becker

et al.

2020 (the 2020 Ecology and Evolution paper). Predicted distribution patterns from this and the Becker

et al.

(2020 TM) SDM for common bottlenose dolphin are very similar, and although the highest density value on the PMSR plot is 0.2282 and on the Becker

et al.

(2020 TM) plot it is 1.55, the top density RANGES overlap (

i.e.,

0.1295-0.2282 vs. 0.0085-1.55, respectively); similar to Baird's beaked whale, this is a case where there were a few high pixel values (in this case in the extreme SW corner of the CCE study area and outside the PMSR Study Area), which served to increase the highest value of the density range presented in the Becker

et al.

2020 TM plot. Density values within the PMSR Study Area are similar for this species. NMFS concurs with this analysis and confirms it does not change our analysis or findings.

Dall's porpoise.

Becker

et al.

(2016) was erroneously cited as the source of the density surface for the Dall's porpoise in the PMSR Density Technical Report, but the plot is consistent with the multi-year average density plot developed using 1991-2014 survey data as described in Becker

et al.

2020 (the 2020 Ecology and Evolution paper). While the legend in the PMSR density plot presents density values up to 0.4939, the range of the highest value plotted on the map within the PMSR Study Area is 0.0911-0.1435. In summer/fall, highest densities of Dall's porpoise occur north of the PMSR Study Area. Density values within the PMSR Study Area are similar between those presented in the PMSR Density Technical Report and Becker

et al.

(2020 TM), although a bit lower in the latter, but of the same order of magnitude. NMFS concurs with this analysis and confirms it does not change our analysis or findings.

Long-beaked common dolphin.

The data source is cited as “Becker

et al.

in prep.”, so the density estimates used for the PMSR analysis were the multi-year average predictions from the SDMs built

with 1991-2014 survey data (

i.e.,

the model presented in the Becker

et al.

2020 (the 2020 Ecology and Evolution paper). Predicted distribution patterns from this and the Becker

et al.

(2020 TM) SDM for long-beaked dolphin are very similar, and density values within the PMSR Study Area are also very similar for this species, with a few higher pixels in the Becker

et al.

(2020 TM) serving to increase the highest density range, but all within the same order of magnitude as the PMSR values. NMFS concurs with this analysis and confirms it does not change our analysis or findings.

Northern right whale dolphin.

The data source is cited as “Becker

et al.

in prep.”, so the density estimates used for the PMSR analysis were the multi-year average predictions from the SDMs built with 1991-2014 survey data (

i.e.,

the model presented in the Becker

et al.

2020 (2020 Ecology and Evolution paper). Predicted distribution patterns from this and the Becker

et al.

(2020 TM) SDM for northern right whale dolphin are very similar, and although the highest density value on the PMSR plot is 0.1430 and on the Becker

et al.

(2020 TM) plot it is 3.07, the top density RANGES overlap (

i.e.,

0.0989-0.1430 vs. 0.0837-3.07, respectively); similar to some of the other species, this is a case where there were a few high pixel values (in this case north and outside the PMSR Study Area), which served to increase the highest value of the density range presented in the Becker

et al.

2020 TM plot. Density values within the PMSR are similar for this species. NMFS concurs with this analysis and confirms it does not change our analysis or findings.

Pacific white-sided dolphin.

The data source is cited as “Becker

et al.

in prep.”, so the density estimates used for the PMSR analysis were the multi-year average predictions from the SDMs built with 1991-2014 survey data. Density values within the PMSR Study Area are similar between the two model predictions, although the distribution patterns reveal some differences; the multi-year 1991-2014 average plot used for the PMSR show higher densities just north of Point Conception as compared to the multi-year 1996-2018 average plot presented in Becker

et al.

(2020 TM). NMFS concurs with this analysis and confirms it does not change our analysis or findings.

Risso's dolphin.

The data source is cited as “Becker

et al.

in prep.”, so the density estimates used for the PMSR analysis were the multi-year average predictions from the SDMs built with 1991-2014 survey data (

i.e.,

the model presented in the Becker

et al.

2020 (the 2020 Ecology and Evolution paper). Both the density values and distribution patterns within the PMSR Study Area are similar between the two model predictions. NMFS concurs with this analysis and confirms it does not change our analysis or findings.

Short-beaked common dolphin.

The data source is cited as “Becker

et al.

in prep.”, so the density estimates used for the PMSR analysis were the multi-year average predictions from the SDMs built with 1991-2014 survey data (

i.e.,

the model presented in the Becker

et al.

2020 (the 202 Ecology and Evolution paper). The highest density value on the PMSR plot is 3.82 and on the Becker

et al.

(2020 TM) plot it is 2.95; however, density estimates from the latter are higher throughout much of the PMSR Study Area, particularly throughout the Southern California Bight and extending to the north/northeast. Similar to both fin and humpback whales, the point estimate for 2018 was the highest yet for short-beaked common dolphin (1,056,308 dolphins). Therefore, the short-beaked common dolphin density surface used in the PMSR analysis is likely biased-low to some extent, but, as noted above, the Becker

et al.

(2020 TM) estimates were not available at the time the Navy was identifying density data for the PMSR analysis. NMFS concurs with this analysis and confirms it does not change our analysis or findings.

Sperm whale.

The data source is cited as “Becker

et al.

in prep.”, so the density estimates used for the PMSR analysis were the multi-year average predictions from the SDMs built with 1991-2014 survey data. As noted in Becker

et al.

(2020 TM), the sperm whale SDM had some of the worst model metrics among all species and predicted distribution patterns matched poorly to actual sightings during the surveys, so the density data used for the PMSR analysis are more appropriate for this species. NMFS concurs with this analysis and confirms it does not change our analysis or findings.

Striped dolphin.

The data source is cited as “Becker

et al.

in prep.”, so the density estimates used for the PMSR analysis were the multi-year average predictions from the SDMs built with 1991-2014 survey data (

i.e.,

the model presented in the Becker

et al.

2020 (the 2020 Ecology and Evolution paper). Although the Becker

et al.

(2020 TM) shows higher densities throughout much of the CCE study area, the density values within the PMSR Study Area don't vary by more than an order of magnitude between the two model predictions. NMFS concurs with this analysis and confirms it does not change our analysis or findings.

Overall summary and conclusions.

The SWFSC habitat modeling team has been developing SDMs for the CCE study area for more than 20 years. Over this time period, the availability of additional survey data (which increases sample sizes and also increases the range of habitat covariate values used to parameterize the models), as well as methodological advances, have resulted in substantial improvements to the SDMs and associated model-derived density estimates. The latest models include data collected from the most recent SWFSC survey conducted in 2018, and SMDs derived from the full set of 1991-2018 survey data are presented in Becker

et al.

(2020 TM). These data were not available when the Navy was identifying density data to use for the PMSR analysis. Although the source of density data could have been more clearly identified in the PMSR Density Technical Report, the Navy consistently used density data that were available from the previous set of SDMs that were developed using 1991-2014 survey data.

For most species, the multi-year density surfaces derived from the two separate sets of models are similar, revealing generally consistent distribution patterns and abundance estimates that are in the same order of magnitude within the PMSR Study Area. In some cases, density estimates appear to differ by more than an order of magnitude based on a comparison of density plots, but this is due to a few high pixel estimates located outside the PMSR Study Area that determine the upper bound of the highest density range, and does not indicate big differences in the density overall or across the area.

Species for which density estimates differ substantially include fin whale and humpback whale, due to the methods used in Becker

et al.

(2020 TM) to ensure that the multi-year average density surfaces better accounted for documented increases in the populations of both these species between 1991 and 2018. In addition, due to the increase in the numbers of short-beaked common dolphins occurring in the PMSR Study Area in recent years, the Becker

et al.

(2020 TM) density estimates for this species are also substantially higher than previous estimates. While the most recent models were not available at the time the Navy was identifying density data to use for the PMSR analysis, we have qualitatively considered this information in this final rule, and we have found that these differences would not change any of the required findings. Also, we note that the Becker

et al.

(2020 TM) SDMs, as well as SDMs developed recently for the Southern California Current (Becker

et al. In Press,

Frontiers in Marine Science), will be used in the Navy's upcoming Hawaii-California Testing and Training (HCTT) analysis, which includes the PMSR Study Area.

Uncertainty in Density Estimates

Comment 7:

The Commission comments that for Phase III activities in the HSTT Study Area, the Navy used more refined density estimation methods for cetaceans and accounted for uncertainty in the density and group size estimates that seeded its animat modeling (Navy 2018). The PMSR Density Technical Report indicated that uncertainty in its density and group size estimates for the PMSR Study Area was incorporated but did not specify what type of uncertainty or what, if any, distribution was used. The PMSR Density Technical Report also did not specify whether uncertainty was used for its density estimates for pinnipeds. NMFS similarly did not include in the preamble to the proposed rule any details regarding whether and how uncertainty was incorporated into either the density or group size estimates. The Commission recommends that NMFS (1) clarify whether and how uncertainty was incorporated in the density and group size estimates, including densities for pinnipeds, and specify the distribution(s) used and, (2) if uncertainty was not incorporated, re-estimate the numbers of takes based on the uncertainty inherent in the density estimates (

e.g.,

Becker

et al.

2020) or the underlying references (

e.g.,

Lowry 2002, Lowry

et al.

2014, NMFS SARs,

etc.

). If NMFS chooses not to incorporate uncertainty in its density estimates, including for pinnipeds, the Commission recommends that NMFS specify why it did not do so in the preamble to the final rule.

Response:

As noted in the PMSR Density Technical Report the Navy did not apply statistical uncertainty outside the survey boundaries into non-surveyed areas, since it deemed application of statistical uncertainty would not be meaningful or appropriate. We note that there are no measures of uncertainty (

i.e.,

no coefficient of variation (CV), standard deviation (SD), or standard error (SE)) provided in NMFS Pacific Stock Assessment Report (SAR) Appendix 3 (Carretta

et al.

2019) as well as the 2021 draft Pacific SAR, associated with the abundance data for any of the pinniped species present in Southern California. Although some measures of uncertainty are presented in some citations within the SAR and in other relevant publications for some survey findings, it is not appropriate for the Navy to attempt to derive summations of total uncertainty for an abundance when the authors of the cited studies and the SAR have not. For additional information regarding use of pinniped density data, see the HSTT Density Technical Report Section 11. As a result of the lack of published applicable measures of uncertainty for pinnipeds during this analysis, the Navy did not incorporate measures of uncertainty into the pinniped density estimates. NMFS independently reviewed the methods and densities used by the Navy and concurs that they are appropriate and reflect the best available science.

Criteria Thresholds

General Threshold Comments

Comment 8:

The Commission has supported the weighting functions and associated thresholds used for Navy Phase III activities (Navy 2017b). However, numerous more recent studies provide additional information on behavioral audiograms (

e.g.,

Cunningham and Reichmuth 2015, Branstetter

et al.

2017, Kastelein

et al.

2017b and 2019a, Sills

et al.

2020a, Kastelein 2021a and b, Ruscher

et al.

2021, and Sills

et al.

2021) and temporary threshold shift (TTS) (

e.g.,

Kastelein

et al.

2017a and c, Popov

et al.

2017, Kastelein

et al.

2018a and b, 2019b-d, and 2020a-f, Sills

et al.

2020b, Kastelein

et al.

2021a and b). The Navy discussed only a few of these references in its Draft Supplemental Environmental Impact Statement (DSEIS) and LOA application. It also noted that the otariid and phocid composite audiograms are consistent with recently published behavioral audiograms of pinnipeds but did not provide any references, including those denoted herein, in its LOA application. NMFS similarly did not discuss any of the aforementioned references in its preamble to the proposed rule, whether the composite audiograms were consistent with the recently-reported behavioral audiograms or whether the criteria, presumably the TTS (and thus permanent threshold shift (PTS)) thresholds, were still considered conservative as compared to the recently-reported TTS data for harbor porpoises, harbor seals, and California sea lions. As such, the Commission recommends that NMFS specify in the preamble to the final rule whether the aforementioned references support the continued use of the current weighting functions and PTS and TTS thresholds for the various functional hearing groups and, if the newer data indicate that either the current weighting functions or PTS and TTS thresholds would significantly underestimate impacts, specify whether and how it plans to revise them.

Response:

NMFS is aware of these recent papers (Kastelein

et al.

2021a and b) and is currently working with the Navy to update NMFS' Technical Guidance for Assessing the Effects of Anthropogenic Sound on Marine Mammal Hearing Version 2.0 (Acoustic Technical Guidance) (NMFS 2018) to reflect relevant papers that have been published since the 2018 update on our 3-5 year update schedule in the Acoustic Technical Guidance. First, we note that the recent peer-reviewed updated marine mammal noise exposure criteria by Southall

et al.

(2019a) provide identical PTS and TTS thresholds and weighting functions to those provided in NMFS' Acoustic Technical Guidance.

NMFS will continue to review and evaluate new relevant data as it becomes available and consider the impacts of those studies on the Acoustic Technical Guidance to determine what revisions/updates may be appropriate. However, any such revisions must undergo peer and public review before being adopted, as described in the Acoustic Guidance methodology. In the meanwhile, NMFS has also carefully considered the other references that the commenter cites, and while some of the relevant data may potentially suggest changes to TTS/PTS thresholds for some species, any such changes would not be expected to change the predicted take estimates in a manner that would change the necessary determinations supporting the issuance of these regulations, and the data and values used in this rule reflect the best available science.

In-Water Behavior Thresholds for Explosives

Comment 9:

The Commission comments that the Navy routinely requests and NMFS routinely authorizes behavior takes of marine mammals associated with exposure to single in-air explosive events (

e.g.,

missile launch noise and sonic booms), including those that occur in the PMSR Study Area (section 6.6 in the Navy's LOA application). The Commission states that NMFS has based its take estimates on the numbers of animals that have responded behaviorally to single launch events, including for the PMSR proposed rule (see section 6.6 in the Navy's LOA application and 84 FR 28470 (June 19, 2019), as one example for previous authorizations issued for launch activities at SNI). The

Commission states that “[c]ontinuing to dismiss the fact that a single explosive event, including that of a 500-lb bomb, has the potential to cause behavior takes to marine mammals underwater is illogical . . . given that an animal exposed to such an event is expected to exhibit the factors the Navy differentiated as a behavioral response in Department of the Navy (2017b) and NMFS routinely authorizes behavior takes for such events when exposed in air, including for the Navy's own proposed launch activities under the PMSR proposed rule.” The Commission also states that the Navy, and in turn NMFS, has not provided adequate justification for dismissing the possibility that single underwater detonations can cause a behavioral response and therefore again recommends that NMFS estimate and ultimately authorize behavior takes of marine mammals during all in-water explosive activities, including those that involve single detonations consistent with in-air explosive activities in the final rule. If NMFS does not authorize behavior takes of marine mammals for all in-water explosive activities, the Commission recommends that NMFS justify in the preamble to the final rule why it believes that marine mammals, including pinnipeds, would only be taken by single in-air explosive detonations and not single in-water explosive detonations. The Commission further recommends that NMFS and the Navy revise the behavior thresholds for in-water explosive sources for Phase IV activities and ensure that any such threshold is based on data that involve impulsive sources, rather than the currently-used threshold that was based on non-impulsive tones.

Response:

NMFS does not ignore the possibility that single underwater detonations can cause a behavioral response. The current take estimate framework allows for the consideration of animals exhibiting behavioral disturbance during single explosions as they are counted as “taken by Level B harassment” if they are exposed above the TTS threshold, which is 5 decibels (dB) higher than the behavioral harassment threshold. We acknowledge in our analysis that individuals exposed above the TTS threshold may also be harassed by behavioral disruption and those potential impacts are considered in the negligible impact determination. Neither NMFS nor the Navy are aware of evidence to support the assertion that animals will have significant behavioral responses (

i.e.,

those that would rise to the level of a take) to temporally and spatially isolated explosions at received levels below the TTS threshold. However, if any such responses were to occur, they would be expected to be few and to result from exposure to the somewhat higher received levels bounded by the TTS thresholds and would thereby be accounted for in the take estimates. The derivation of the explosive injury criteria is provided in the 2017 technical report titled “Criteria and Thresholds for U.S. Navy Acoustic and Explosive Effects Analysis (Phase III)”.

Regarding the assertion that the approaches for assessing the impacts from a single underwater detonation and a single in-air detonation are inconsistent, we disagree. Both approaches/thresholds are based on the best available data. As noted above, we are unaware of data suggesting that marine mammals will respond to single underwater explosive detonations below the TTS threshold in a manner that would qualify as a take. Conversely, for single in-air detonations such as missile launch noise and sonic booms, there are extensive data supporting the application of the lower behavioral thresholds,

i.e.,

pinnipeds moving significant distances or flushing in response to these in-air levels of sounds.

Regarding the recommendation that explosive thresholds used for assessing impacts in Phase IV be based on impulsive sources, NMFS will continue to work with the Navy to ensure that the best available science is used in the development and revision of the thresholds to be used to assess acoustic impacts in Phase IV of the Navy actions.

In-Water Takes for Explosives

Comment 10:

The Commission comments that the number of takes that NMFS proposed to authorize does not accurately reflect the group sizes of various species. The Navy's 2017 report, “Dive Distribution and Group Size Parameters for Marine Species Occurring in the U.S. Navy's Atlantic and Hawaii‐Southern California Training and Testing areas”, specified that the mean group size of long-beaked common dolphins was 255, 16 for the offshore stock of common bottlenose dolphins, and 56 for striped dolphins. However, NMFS proposed to authorize a total of 119 takes of long-beaked common dolphins, 11 takes of offshore bottlenose dolphin, and 2 takes of striped dolphins per year (see Table 18 of the proposed rule)—all of which are less than the mean group sizes reported by the Navy. The numbers of takes of northern right whale dolphins, Pacific white-sided dolphins, Risso's dolphins, short-beaked common dolphins, and sperm whales also are less than the mean group sizes specified in Table 48 of the above report. For other species that routinely occur in the PMSR Study Area but for which model-estimated takes were zero (

e.g.,

Cuvier's beaked whales, Baird's beaked whales, Kogia spp.,

etc.

), NMFS did not propose to authorize any takes (see Table 18 of the proposed rule). The Commission recommends that NMFS, at minimum, authorize Level B harassment (behavior) takes that are at least the mean group size reported in Table 48 of the Navy 2017 report for all species in which model-estimated takes are either less than mean group size (long- and short-beaked common dolphins, offshore bottlenose dolphins, striped dolphins, northern right whale dolphins, Pacific white-sided dolphins, Risso's dolphins, and sperm whales) or zero for those species that routinely occur in the PMSR Study Area (

e.g.,

Cuvier's beaked whales, Baird's beaked whales, Kogia spp.,

etc.

) in the final rule.

Response:

NMFS indicates in the

Description of Marine Mammals and Their Habitat in the Area of the Specified Activities

section of this final rule that the following species/stocks had zero calculated estimated takes: Bryde's whale (Eastern Tropical Pacific), Gray whale (Western North Pacific), Sei whale (Eastern North Pacific), Baird's beaked whale (California, Oregon, and Washington), Bottlenose dolphin (California Coastal), Cuvier's beaked whale (California, Oregon, and Washington), Harbor Porpoise (Morro Bay), Killer whale (Eastern North Pacific Offshore, Eastern North Pacific Transient or West Coast Transient), Mesoplodont spp. (California, Oregon, and Washington), Short-finned pilot whale (California, Oregon, and Washington), and Northern fur seal (California). NMFS continues to agree with the Navy's analysis; therefore, no takes were authorized for those species where takes were modeled to be zero.

However, to precautionarily ensure adequate incidental take coverage should the Navy encounter and expose a larger group than was originally estimated and proposed, the authorized annual take by Level B harassment was increased to group size for 7 dolphin species where the annual takes proposed were fewer than the species group size, specifically for Long- and Short-beaked common dolphins, Offshore Bottlenose dolphins, Striped dolphins, Northern right whale dolphins, Pacific white-sided dolphins, and Risso's dolphins. These changes are reflected in Table 21 and explained in detail in the

Changes from the Proposed Rule to the Final Rule

section of this final rule. For sperm whales, however,

given they prefer deeper waters and Navy activities are at the surface or near-surface, their secondary range includes areas of higher latitudes in the PMSR Study Area, NMFS concurs with the Navy's initial proposed take and does not find that an increase in the take estimates is warranted.

In-Air Thresholds for Explosives

Comment 11:

The Commission comments that the in-air PTS, TTS, and behavior thresholds were absent from both the Navy's LOA application and NMFS' preamble to the proposed rule, and that it is unclear what, if any, thresholds were used to inform either the Navy's or NMFS' impact analyses. The Commission recommends that NMFS provide any Phase IV in-air and in-water PTS and TTS thresholds and associated weighting functions to the public for review and comment, consistent with the Phase III in-water auditory thresholds. The Commission also stated that, in its May 2019 letter regarding a proposed incidental harassment authorization for launch activities at SNI, the unweighted behavior threshold of 100 dB re 20 μPa2-sec to be applied to all pinnipeds from Department of the Navy (2017b) was inconsistent with other recent proposed and final rules for the U.S. Air Force (Air Force; 84 FR 335; January 24, 2019 and 84 FR 14321; April 10, 2019) and other recent proposed rules or authorizations involving other launch activities (83 FR 57434; November 15, 2018, 82 FR 49334; October 25, 2017, 82 FR 6463; January 19, 2017, 81 FR 18584; March 31, 2016,

etc.

). Further, the Commission reiterates its 2019 recommendation that NMFS compile all in-air response data and determine whether the in-air behavior thresholds can be revised or whether additional paired visual and acoustic monitoring data are necessary to refine the in-air thresholds before issuing the PMSR final rule. If the thresholds cannot be revised with data currently available, the Commission recommends that NMFS (1) ensure that the Navy, the Air Force, and any other relevant entities collect the necessary data to inform in-air behavior thresholds, and (2) revise, allow for public comment on, and finalize those thresholds in the next 3 years.

Response:

The Commission is correct that the in-air behavioral thresholds were missing, but these have now been added to Table 12 (Behavioral Thresholds). However, the Navy's testing and training activities (outside of target and missile launches) are modeled at or near-surface (essentially underwater) and the in-air behavioral thresholds would not apply to those other testing and training activities, as they were modeled underwater. The in-air thresholds would apply to the target and missile launches on SNI.

Regarding the Commission's comment that the unweighted behavior threshold of 100 dB re 20 μPa2-sec applied to all pinnipeds from Department of the Navy (2017b) was inconsistent with other recent proposed and final rules for the U.S. Air Force (Air Force; 84 FR 335; January 24, 2019 and 84 FR 14321; April 10, 2019), it is true that the Navy is using in-air behavior thresholds different from what is used by the U.S. Air Force. The Navy's thresholds in the Criteria and Thresholds for U.S. Navy Acoustic and Explosive Effects Analysis (Phase III) Technical Report (U.S. Department of the Navy, 2017) for TTS/PTS are correct, while for behavior, the Navy uses a value of 100 dB sound exposure level (SEL) for all pinnipeds rather than 90 dB sound pressure level (SPL) for harbor seals/100 dB SPL for all other pinnipeds. In this case, the issues the Commission points out regarding in-air behavioral thresholds are not applicable, as the estimated takes are based on the last 3 years of pinniped observation from Navy's monitoring reports and are not directly based on specific in-air thresholds.

The Navy selects beaches to survey based largely on where sound received is expected to reach 100 dB SEL or greater and where animals are reacting to launch noises. In the case of harbor seals, the Navy is already monitoring beaches where sound levels are less than 100 dB SEL and often under 90 dB SPL (site O—Phoca Reef and Pirates Cove). The Navy is monitoring at site O because oftentimes the harbor seals are not hauled out on the western end of SNI on the typically monitored beaches during launch events. The Navy is cognizant of the fact that some harbor seals are reacting to sound levels lower than 90 dB SPL. Accordingly, the Navy is monitoring those pinnipeds and requesting additional take by Level B harassment to account for this potential.

NMFS indicated in the

Acoustic Thresholds

sections of both the proposed rule and this final rule that using the best available science, NMFS, in coordination with the Navy, has established acoustic thresholds that identify the most appropriate received level of underwater sound above which marine mammals exposed to these sound sources could be reasonably expected to directly experience a disruption in behavior patterns to a point where they are abandoned or significantly altered, to incur TTS (equated to Level B harassment), or to incur PTS of some degree (equated to Level A harassment). Thresholds have also been developed to identify the pressure levels above which animals may incur non-auditory injury from exposure to pressure waves from explosive detonation. Refer to the “Criteria and Thresholds for U.S. Navy Acoustic and Explosive Effects Analysis (Phase III)” report (U.S. Department of the Navy, 2017c) for detailed information on how the criteria and thresholds were derived. The criteria and thresholds in this document have been available for the public at

https://www.hstteis.com/Documents/2018-Hawaii-Southern-California-Training-and-Testing-Final-EIS-OEIS/2018-Final-EIS-OEIS-Supporting-Technical-Documents.

That said, regarding the recommendation that NMFS compile all in-air response data and determine whether the in-air behavior thresholds can be revised or whether additional paired visual and acoustic monitoring data are necessary to refine the in-air thresholds before issuing the PMSR final rule. NMFS will not be refining the in-air thresholds for this final rule. The Navy's proposed Phase IV criteria are still in development and NMFS will work with the Navy and others within NOAA on any proposed changes and review the in-air thresholds for pinnipeds and, if appropriate, update NMFS' Acoustic Technical Guidance, which will include peer review and public comment. NMFS will continue to review and evaluate new relevant data as it becomes available and consider the impacts of those studies on the Acoustic Technical Guidance to determine what revisions/updates may be appropriate. In the meanwhile, the data and values used in this rule reflect the best available science.

In-Air Behavior Takes for Launch Activities

Comment 12:

The Commission comments that, similar to the various in-air thresholds, the take estimation method for launch activities was omitted from the preamble to the proposed rule. NMFS indicated in the preamble to the proposed rule that it had reviewed the Navy's data, methodology, and analysis and determined that it was complete and accurate (86 FR 37822; July 16, 2021). If that was the case, it is unclear why the details were omitted from the proposed rule for the very activities that were estimated to result in the greatest numbers of takes for California sea lions, harbor seals, and elephant seals (see Tables 18 and 19 in the proposed rule). The Commission claims that the Navy's 2019 proposed authorization

also indicated that a total of 4,940 Level B harassment takes of California sea lions occurred during 18 launches in the 2015-2017 monitoring seasons (84 FR 18822; May 2, 2019), which equates to an average of 275 takes per launch. The Commission claims there were only 15 launches and the average number of takes per launch in the 2019 IHA should have been 329 rather than 275. The Commission comments that NMFS must specify the underlying references, assumptions, and methods used to estimate the numbers of takes for all activities for which taking would be authorized for each

Federal Register

notice.

Response:

NMFS indicated in the preamble to the proposed rule that it had reviewed the Navy's data, methodology, and analysis presented in section 5.2 (Incidental Take of Marine Mammals from Launch Activities at San Nicolas Island) of the Navy's rulemaking/LOA application, which were based on monitoring results from past launches, and determined that it was complete and accurate. Specifically, the estimation of the amount of take by Level B harassment that would be expected to occur as a result of launch events was based on the total take by species observed for three previous monitoring seasons divided by the number of launch events over that time period. NMFS has added additional details in the preamble in the

Estimated Take of Marine Mammals

section of this final rule to clarify how the takes estimated were derived for target and missile launches on SNI. This is also described in the paragraphs below.

For California sea lions, take estimates were derived from three monitoring seasons where an average of 274.44 instances of take of sea lions by Level B harassment occurred per launch event. Therefore, 275 sea lions was then multiplied by 40 launch events, for a conservative take estimate of 11,000 instances of take for California sea lions by Level B harassment. This estimate is conservative because the Navy has not conducted more than 25 launch events (although authorized for more) in a given year since 2001.

For harbor seals a total of 12 takes were derived from previous monitoring seasons and multiplied by 40 launch events for a total of 480 instances of take by Level B harassment.

For northern elephant seals, take estimates were derived from previous monitoring seasons where an average of 0.61 instances of take of northern elephant seals by Level B harassment occurred per launch event. Therefore, one northern elephant seal was then multiplied by 40 launch events for a conservative take estimate of 40 instances of take of northern elephant seals by Level B harassment. Generally, northern elephant seals do not react to launch events other than by exhibiting simple alerting responses, such as raising their heads or temporarily going from sleeping to being awake; however, to account for the rare instances where they have reacted, the Navy considered that some northern elephant seals could be taken during launch events.

The Commission is incorrect about the number of launches that took place during the monitoring periods from 2015-2017; it was, in fact, 18 launches that took place. The launch activities are described in the Navy's 2014-2019 monitoring report, which NMFS provided to the Commission. Monitoring reports can also be found at

https://www.fisheries.noaa.gov/action/incidental-take-authorization-us-navy-target-and-missile-launch-activities-san-nicolas.

The average number of takes per launch in the 2019 IHA was correct (275 animals) as is the underlying data used to determine the estimated take for the 2019 IHA, the 2020 renewal IHA, and this final rule.

Comment 13:

The Commission comments that the method NMFS used to determine in-air takes is flawed for several reasons. The Commission states the Navy is only able to monitor at most three haulout sites during each launch event. However, California sea lions and harbor seals are present at several additional haulout sites on the west side of SNI. The Navy also estimates the number of pinnipeds hauled out at least 2 hours before the launch occurs. For safety reasons, the observers are not allowed to be at the haulout sites for at least 2 hours before and during a launch. The video cameras that document the responses of the hauled-out animals are able to view only a portion of the animals. Thus, the Commission says it is unclear whether new animals haul out or enter the water in the more than 2 hours after the animals were last counted. When equipment failures occur or launches occur at night, responses are not observed.

Response:

The Navy is committed to several types of monitoring in order to document the responses of hauled-out animals. NMFS has approved the Navy's monitoring methods in previous authorizations and does not believe the methods are flawed. It is correct that the Navy monitors at most 3 haulout sites during each launch and the Navy attempts to vary the sites they are monitoring during each launch, so the Navy is not always monitoring the same 3 sites. This is precisely for the reason the Commission pointed out, as there are several haulout sites on the west side of SNI. During visual surveys, the Navy also estimates the number of pinnipeds hauled out at least 2 hours before the launch occurs. For safety reasons, the observers are not allowed to be at the haulout sites for at least 2 hours before and during a launch. However, the Navy conducts more than just visual surveys in order to obtain the most accurate information on the number of hauled out animals. Video and acoustic monitoring of up to three pinniped haulout areas and rookeries will be conducted during launch events that include missiles or targets that have not been previously monitored using video and acoustic recorders for at least three launch events. Video monitoring cameras would be either high-definition video cameras, or Forward-Looking Infrared Radiometer (FLIR) thermal imaging cameras for night launch events. The Navy is also experimenting with time-lapse photography to fill in any data gaps that may occur from the other methods of monitoring. Marine mammal monitoring includes multiple surveys during the year that record the species, number of animals, general behavior, presence of pups, age class, gender and reactions to launch noise or other natural or human caused disturbances, in addition to environmental conditions that may include tide, wind speed, air temperature, and swell. Between the different methods of monitoring, NMFS is confident that the Navy will be able to continue to complete their monitoring requirements and record accurate data if equipment issues arise or launches occur during the day or night.

Comment 14:

The Commission comments that the criteria that the Navy used to enumerate takes under a previous authorization and in previous monitoring reports were based on animals moving at least 10 m (11 yd; 84 FR 37845; August 2, 2019). NMFS' more recent criteria, including those that it used for the U.S. Air Force's 2019 final rule (see Table 9; 84 FR 337; January 24, 2019), are based on animals moving at least two body lengths (Level 2 response). The 10-m (11-yd) metric is much greater than the estimated 4 or 5 m (4 or 5 yd) that adult female and male sea lions move in two body lengths. The Commission is concerned that NMFS is allowing Department of Defense agencies to use two different sets of criteria for the same activities (

i.e.,

launch activities) as related to the same definition of Level B harassment under section 3(18)(B)(ii) of the MMPA. The

Commission recommends that NMFS specify in the PMSR final rule that the Level B harassment criteria are based on the definitions of Level 2 and 3 responses provided in § 217.65(b)(3)(ii) of the Air Force's final rule.

Response:

In contrast to the activities considered for this final rule, which are considered military readiness activities, the activities that were the subject of NMFS' 2019 rule for the Air Force were not evaluated as military readiness activities; therefore a different definition of Level B harassment applied. For the U.S. Air Force rule, the standard non-military-readiness pinniped thresholds were used. For military readiness activities, the MMPA defines Level B harassment as: “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.” The Navy proposed a slightly different version of the criteria for determining when behavioral response of a hauled pinniped rises to the level of harassment, as is appropriate for use with the definition of Level B harassment associated with military readiness activities. NMFS concurred that this version, which has been used in prior incidental take authorizations associated with launch activities on SNI, is appropriate for evaluating Level B harassment in association with this specified activity. NMFS may re-evaluate these criteria with the Navy for any subsequent applications we receive for these activities.

Comment

15: The Commission comments that NMFS underestimates harbor seal takes as well on SNI. NMFS previously had noted, and the Navy's monitoring reports have confirmed, that harbor seals were not always present when the Navy conducted its monitoring during launch events, and there have not been many places to observe harbor seals during the launches (84 FR 18821; May 2 2019). NMFS indicated that most of the beaches where harbor seals have been hauled out, and which the Navy has been able to monitor, occur in area O, which is not in the trajectory of most of the launches. That may be the case, but the animals still have responded to sound levels that range from 79-99 dB 20 re μPa at those beaches. NMFS also indicated that harbor seal presence at the haulout sites is dependent on tides. Since the Navy cannot predict whether it will conduct launches during high or low tide, the Commission states NMFS must assume that harbor seals have the potential to be present during each launch irrespective of the tidal cycle. Furthermore, the Navy focuses much of its monitoring on sea lion haulout sites, where harbor seals generally do not haul out. NMFS noted that harbor seals do not prefer beaches with California sea lions present (84 FR 18821; May 2, 2019). Moreover, and as routinely is the case for harbor seals, Navy monitoring reports from 2014-2017 indicated that for all but one launch 100 percent of the hauled-out harbor seals within the view of the camera responded to the launch. Thus, the Commission says that 12 harbor seals taken per launch on all of SNI is illogical and a vast underestimate.

Response:

NMFS disagrees with the Commission's assertion that harbor seal takes are too low. Approximately 42 harbor seals were estimated to have been affected during the June 2019 through March 2020 monitoring period. These figures are approximate and included extrapolations for pinnipeds on portions of the beach that were not within the field of view of the camera. These estimates correspond to an average rate of 4.08 harbor seals affected per launch and are certainly within the estimated 12 harbor seals taken per launch. Only 12 missile launch events occurred during that period, while the Navy was authorized for 40 events. It is incorrect to state that the Navy only focuses on California sea lion beaches. During the 2019-2020 monitoring period, the Navy had cameras set up on Phoca Reef, which corresponds to site O (referred to by the commenter) where harbor seals tend to haul out. The Navy was able to monitor Phoca Reef during approximately half of the launches. The Navy is required to monitor 3 sites during launches, and these sites can consist of any combination of Dos Coves South, Vizcaino Point South, Red Eye West, Red Eye East, Bachelor Beach, and Phoca Reef. It is not possible to monitor all of these sites for every launch, and the Navy makes a decision about where to monitor based on several factors, including local weather conditions, the type of launch activity planned, the types and location of pinnipeds hauled out, as well as tidal factors.

Comment 16:

The Commission commented that Navy's take estimation method is not consistent with either the method recently used by the U.S. Air Force for its proposed and final rule (84 FR 321; January 24, 2019 and 84 FR 14314; April 10, 2019, respectively) or the intent of the MMPA to estimate the numbers of marine mammals that are likely to be disturbed. The U.S. Air Force based its take estimates on abundance estimates at the various haulout sites based on Lowry

et al.

(2017), previous response rates of the various pinniped species, and the number of launches per year. Specifically for harbor seals, the Commission says NMFS should have estimated the number of takes based on a 100-percent response rate and the number of animals that were documented in areas J through N on SNI in 2015 and area O in 2014, as stipulated in Lowry

et al.

(2017) and as was considered best available science for the U.S. Air Force's proposed and final rule. Using that approach, 110 harbor seals could be taken during each of the 40 proposed launch events, for a total of 4,400 harbor seal takes. For California sea lions, the response rate should be based on the number of sea lions that moved a `short distance' according to the 2014-2017 monitoring reports multiplied by the number of sea lions in the same areas in 2015 from Lowry

et al.

(2017) and the number of launches. The Commission states that a similar approach should be taken for elephant seals. Accordingly, the Commission recommends that NMFS (1) authorize 4,400 Level B harassment takes of harbor seals, and (2) estimate Level B harassment takes of California sea lions and elephant seals based on the numbers of both species in areas J through N in 2015 as stipulated in Lowry

et al.

(2017), response rates based on each species moving a short distance according to the 2014-2017 monitoring reports, and 40 proposed launch events in the final rule.

Response:

The difference in methods of take estimation between the Navy and the U.S. Air Force are based on what is appropriate for each agency based on the activities that are being conducted. It does not mean that one method is not appropriate for estimating take.

For harbor seals, NMFS believes the amount of Level B harassment take suggested as appropriate by the Commission would be an overestimate based on previous observations during Navy's launch events. Before the launch events, the Navy monitors several sites around the western end of SNI to determine where pinnipeds are hauled out and what species are on the beaches. During this pre-launch monitoring, harbor seals are frequently not present. For harbor seals on SNI, the estimated takes are based on pinniped observation from Navy's monitoring reports and not directly based on specific in-air thresholds. The beaches that the Navy surveys are largely based on where sound received is expected to reach 100 dB SEL or greater and where animals are reacting to launch noises. In the case of

harbor seals, the Navy is already monitoring beaches where sound levels are less than 100 dB SEL and often under 90 dB SPL (site O—Phoca Reef and Pirates Cove). The Navy is monitoring at site O because oftentimes the harbor seals are not hauled out on the western end of SNI on the typically monitored beaches during launch events. In addition, the Navy has previously surveyed other parts of SNI to determine if pinnipeds are reacting in response to launch events. The Navy conducted surveys of the eastern end of SNI and did not find pinnipeds reacting to launch events. The estimated take for harbor seals was based on the total number of takes (12) over a 3-yr monitoring period multiplied by 40 launch events for a total of 480 instances of take by Level B harassment. Using the total number of takes (12) was a change from the proposed IHA in 2019 (84 FR 18809; May 2, 2019) in which we used an average number of takes multiplied by the number of launches. The estimated take would be lower (120 harbor seals) if the average was used, as was the case for California sea lions and Northern elephant seals. The take estimate was revised from 120 to 480 harbor seal instances of take by Level B harassment to possibly account for any additional harbor seals that hauled out and reacted to launch events.

NMFS concludes that the number of authorized take is adequate and sufficient for California sea lions and Northern Elephant seals. For California sea lions, take estimates were derived from Navy monitoring reports in which an average of 274.44 instances of take of sea lions by Level B harassment occurred per launch event. Therefore, 275 sea lions was multiplied by 40 launch events, for a conservative take estimate of 11,000 instances of take for California sea lions by Level B harassment. Generally, northern elephant seals do not react to launch events other than by exhibiting simple alerting responses, such as raising their heads or temporarily going from sleeping to being awake; however, to account for the rare instances where they have reacted, the Navy considered that some northern elephant seals could be taken during launch events. For Northern elephant seals an average of 0.61 instances of take of northern elephant seals by Level B harassment occurred per launch event from the Navy's monitoring reports. Therefore, one northern elephant seal was then multiplied by 40 launch events for a conservative take estimate of 40 instances of take of northern elephant seals by Level B harassment.

As reported in the Navy 2014-2019 comprehensive monitoring report from the previous rule, approximately 3,876 California sea lions, 99 Harbor seals, and 11 Northern elephant seals (average 144 California sea lions, 3.5 harbor seals, and 0.4 Northern elephant seals) were estimated to have been affected by launches conducted during that monitoring period. The estimates also included extrapolations for pinnipeds on portions of the beach that were not within the field of view of the camera. During the 2014-2019 monitoring period 27 launch events occurred at SNI even though 40 launch events annually were authorized. If NMFS had used these averages the estimated take would have been even lower than what NMFS is authorizing in this final rule.

In summary, NMFS believe the Level B harassment take estimates for pinnipeds on SNI are sufficient based on actual field monitoring conducted by the Navy of the pinniped haulout areas that could potentially be affected by noise from launch events.

In-Water Mortality and Injury Thresholds for Explosives

Comment 17:

The Commission notes that the constants and exponents associated with the impulse metrics for both onset mortality and onset slight lung injury have been amended from those used in Tactical Training Theater Assessment and Planning (TAP) I and Phase II activities, and that the Navy did not explain why the constants and exponents have changed when the underlying data have not. The modifications yield both smaller and larger zones. The Commission states the results are counterintuitive since the Navy presumably amended the impulse metrics to account for lung compression with depth, thus the zones would be expected to be smaller rather than larger the deeper the animal dives. The Commission states that the Navy should provide a sufficient explanation regarding the constants and exponents or specify the assumptions made. NMFS, however, did provide a response in the preamble to the NWTT final rule. It stated that the numerical coefficients are slightly larger in Phase III than in Phase II, resulting in a slightly greater threshold near the surface. It also stated that the rate of increase for the Phase II thresholds with depth is greater than the rate of increase for Phase III thresholds with depth because the Phase III equations take into account the corresponding reduction in lung size with depth (making an animal more vulnerable to injury per the Goertner model; 85 FR 72327; November 12, 2020). The Commission says that NMFS' response in the NWTT final rule does not explain why lower absolute thresholds prevail below 8 m (9 yd) in depth, and why, if lung compression is accounted for in Phase III, the rate of increase of the Phase II thresholds with depth would be greater when lung compression was not accounted for. The Commission again recommends that NMFS explain in the preamble to the final rule why the constants and exponents for onset mortality and onset slight lung injury thresholds for Phase III that consider lung compression with depth result in lower rather than higher absolute thresholds when animals occur at depths greater than 8 m.

Response:

The derivation of the explosive injury equations, including any assumptions, is provided in the 2017 technical report titled “Criteria and Thresholds for U.S. Navy Acoustic and Explosive Effects Analysis (Phase III)”. Specifically, the equations were modified for the current rulemaking period (Phase III) to fully incorporate the injury model in Goertner (1982), specifically to include lung compression with depth. NMFS independently reviewed and concurred with this approach.

The impulse mortality/injury equations are depth dependent, with thresholds increasing with depth due to increasing hydrostatic pressure in the model for both the previous 2015-2020 phase of rulemaking (Phase II) and Phase III. The Commission correctly observes that above 8 m, the Phase II threshold is lower than the Phase III threshold, and below 8 m, the Phase II threshold is greater than the Phase III threshold. The differences in injury and mortality thresholds are due to taking into account the complete Goertner (1994) model in the Phase III criteria, as the Navy has shown in the technical report “Criteria and Thresholds for U.S. Navy Acoustic and Explosive Effects Analysis (Phase III)”. The underlying experimental data used in Phase II and Phase III remain the same, and two aspects of the Phase III revisions explain the relationships the Commission notes:

(1) The numeric coefficients in the equations are computed by inserting the Richmond

et al.

(1973) experimental data into the model equations. Because the Phase III model equation accounts for lung compression, the plugging of experimental exposure values into a different model results in different coefficients. The numeric coefficients are slightly larger in Phase III versus Phase II, resulting in a slightly greater threshold near the surface.

(2) The rate of increase for the Phase II thresholds with depth is greater than the rate of increase for Phase III

thresholds with depth because the Phase III equations take into account the corresponding reduction in lung size with depth (making an animal more vulnerable to injury per the Goertner model), as the commenter notes.

Comment 18:

The Commission comments that, consistent with other Phase III documents, the Navy used the onset mortality and onset slight lung injury criteria to determine only the range to effects, while it used the 50 percent mortality and 50 percent slight lung injury criteria to estimate the numbers of marine mammal takes. That approach is inconsistent with the manner in which the Navy estimated the numbers of takes for PTS, TTS, and behavior for explosive activities. All of those takes have been and continue to be based on onset, not 50-percent values. The Commission comments that NMFS' responses in the corresponding preambles to the final rules, that over predicting impacts by using onset values would not afford extra protection to any animal, is irrelevant from an impact analysis standpoint. NMFS' additional response in the preamble to the NWTT final rule, that estimating takes based on the onset values would over predict effects because many of those exposures would not happen because of effective mitigation (85 FR 72328; November 12, 2020), is unsubstantiated. The Navy has not determined the effectiveness of any of its mitigation measures, and explosive activities for which mitigation measures were implemented still resulted in the deaths of multiple common dolphins in 2011. It would be more prudent for the Navy and NMFS to estimate injuries and mortalities based on onset rather than a 50-percent incidence of occurrence. The Commission recommends that NMFS use onset mortality, onset slight lung injury, and onset gastrointestinal (GI) tract injury thresholds rather than the 50-percent thresholds to estimate both the numbers of marine mammal takes and the respective ranges to effect in the final rule. If NMFS does not implement the Commission's recommendation, the Commission further recommends that in the preamble to the final rule NMFS (1) specify why it is inconsistently basing its explosive thresholds for Level A harassment on onset PTS and for Level B harassment on onset TTS and onset behavioral response, while the explosive thresholds for mortality and non-auditory Level A harassment are based on the 50-percent criteria for mortality, slight lung injury, and GI tract injury, (2) provide scientific justification supporting the assumption that slight lung and GI tract injuries are less severe than PTS and thus the 50-percent rather than onset criteria are more appropriate for estimating Level A harassment for those types of injuries, and (3) justify why the number of estimated mortalities should be predicated on at least 50 percent rather than 1 percent of the animals dying.

Response:

For explosives, the type of data available are different than those available for hearing impairment, and this difference supports the use of different prediction methods. Nonetheless, as appropriate, and similar to take estimation methods for PTS, NMFS and the Navy have used a combination of exposure thresholds and consideration of mitigation to inform the take estimates. The Navy used the range to 1 percent risk of onset mortality and onset injury (also referred to as “onset” in the 2022 PSMR FSEIS/OEIS and the Navy's 2017 technical report titled “Criteria and Thresholds for U.S. Navy Acoustic and Explosive Effects Analysis (Phase III)”) to inform the development of mitigation zones for explosives. Ranges to effect based on 1 percent risk criteria to onset injury and onset mortality were examined to ensure that explosive mitigation zones would encompass the range to any potential mortality or non-auditory injury, affording actual protection against these effects. In all cases, the mitigation zones for explosives extend beyond the range to 1 percent risk of onset non-auditory injury, even for a small animal (representative mass = 5 kg). Given the implementation and expected effectiveness of this mitigation (based on the smaller size of the zone and available monitoring data), the application of the indicated 50-percent threshold is appropriate for the purposes of estimating take. Using the 1 percent onset non-auditory injury risk criteria to estimate take would result in an over-estimate of take, and would not afford extra protection to any animal. Specifically, calculating take based on marine mammal density within the area that an animal might be exposed above the 1 percent risk to onset injury and onset mortality criteria would over-predict effects because many of those exposures will not happen because of the effective mitigation. The Navy and NMFS consider the 50-percent incidence of onset injury and onset mortality occurrence a reasonable representation of a potential effect, and thereby appropriate for take estimation, given the mitigation requirements at the 1-percent onset injury and onset mortality threshold, and the area ensonified above this threshold would capture the appropriate reduced number of likely injuries.

While the approaches for evaluating non-auditory injury and mortality are based on different types of data and analyses than the evaluation of PTS and behavioral disturbance, and are not identical, NMFS disagrees with the commenter's assertion that the approaches are inconsistent, as both approaches consider a combination of thresholds and mitigation (where applicable) to inform take estimates. For the same reasons, it is not necessary for NMFS to “provide scientific justification supporting the assumption that slight lung and GI tract injuries are less severe than PTS,” as that assumption is not part of NMFS' rationale for the methods used. NMFS has explained in detail its justification for the number of estimated mortalities, which is based on both the 50 percent threshold and the mitigation applied at the one percent threshold. Further, we note that many years of Navy monitoring following explosive exercises has not detected evidence that any injury or mortality has resulted from Navy explosive exercises with the exception of one incident with dolphins in California, after which mitigation was adjusted to better account for explosives with delayed detonations (

i.e.,

zones for events with time-delayed firing were enlarged).

Furthermore, for these reasons, the methods used for estimating mortality and non-auditory injury are appropriate for estimating take, including determining the “significant potential” for non-auditory injury consistent with the statutory definition of Level A harassment for military readiness activities, within the limits of the best available science. Using the one percent threshold would be inappropriate and would result in an overestimation of effects, whereas, given the mitigation applied within this larger area, the 50 percent threshold results in an appropriate mechanism for estimating the significant potential for non-auditory injury.

Mitigation Measures

Extents of Zones and Passive Acoustic Monitoring

Comment 19:

The Commission commented that the proposed mitigation zones would not protect high-frequency (HF) cetaceans from PTS. For example, the mitigation zone for a missile is 1,829 m (2,000 yd; Table 23 in the proposed rule), but the mean PTS zones range from 2,177-3,791 m (2,381-4,146 yd) for HF Cetaceans (Table 6-8 in the LOA application).

Similarly, the mitigation zone for an explosive bomb is 2,286 m (2,500 yd; Table 24 in the proposed rule), but the mean PTS zones similarly range from 2,177-3,791 m (2,381-4,146 yd) for HF cetaceans. The appropriateness of such zones is further complicated by aircraft deploying bombs at surface targets directly beneath the aircraft, minimizing the ability to observe the entire extent of the zone(s). In addition, missiles and rockets can be fired from vessels at targets 139 km (75 nmi) away from the firing platform (Table 23 in the proposed rule). In either case, marine mammals could be present in the target area at the time of the launch unbeknownst to the Navy.

Response:

NMFS is aware that some mitigation zones do not fully cover the area in which an animal from a certain hearing group may incur PTS. The mitigation zones extend beyond the respective average ranges to PTS for all marine mammal hearing groups except HF cetaceans (the mitigation zones extend into a portion of the respective average ranges to PTS for this hearing group). The mitigation zones also extend into a portion of the average ranges to TTS for marine mammals. Therefore, depending on the species, mitigation will help avoid or reduce all or a portion of the potential for exposure to mortality, non-auditory injury, PTS, and higher levels of TTS for the largest explosives in bins E10 and bin E6. Explosives in smaller source bins (

e.g.,

missiles in bin E9, rockets in bin E3) have shorter predicted impact ranges; therefore, the mitigation zones will cover a greater portion of the impact ranges for these explosives.

For this small subset of circumstances, NMFS discussed potential enlargement of the mitigation zones with the Navy, but concurred with the Navy's assessment that further enlargement would be impracticable. Specifically, the Navy explained that, as discussed in Chapter 5 (Standard Operating Procedures and Mitigation) of the 2022 PMSR FEIS/OEIS, for explosive mitigation zones any additional increases in mitigation zone size (beyond what is depicted for each explosive activity), or additional observation requirements, would be impracticable to implement due to implications for safety, sustainability, the Navy's ability to meet requirements under Title 10 of the U.S. Code (Title 10 requirements) to successfully accomplish military readiness objectives, and the Navy's ability to conduct testing and training associated with required acquisition milestones or as required to meet operational requirements.

Increasing the mitigation zone sizes would result in larger areas over which firing would need to be ceased in response to a sighting, and therefore would likely increase the number of times detonations would be ceased, which could extend the length of the activity. These impacts could significantly diminish event realism in a way that would prevent the activity from meeting its intended objectives. Explosive missile and rocket events require focused situational awareness of the activity area and continuous coordination between the participating platforms as required during military missions and combat operations. Additionally, Navy determined that the mitigation detailed in Chapter 5 (Standard Operating Procedures and Mitigation) of the 2022 PMSR FEIS/OEIS and mirrored in this final rule, provides the greatest extent of protection that is practicable to implement. NMFS has analyzed the fact that, despite these mitigation measures, some Level A harassment may occur in some circumstances (

i.e.,

for HF cetaceans, as noted by the commenter); the Navy is authorized for these takes by Level A harassment.

Comment 20:

The Commission notes that NMFS included only the SELcum-based ranges to effect in the preamble to the proposed rule (Tables 11-15) and specified that sound from multiple successive explosions can be expected to increase the range to the onset of an impact based on the SELcum thresholds (86 FR 37817; July 16, 2021). Although that may be true relative to the SELcum of a sing

This text is long and has been trimmed here. Open the source document for the complete record.