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

[Docket No. 210701-0141]

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:

Proposed rule; request for comments and information.

SUMMARY:

NMFS has received a request from the U.S. Navy (Navy) to take marine mammals incidental to training and testing activities conducted in the Point Mugu Sea Range (PMSR) Study Area. Pursuant to the Marine Mammal Protection Act (MMPA), NMFS is requesting comments on its proposal to issue regulations and subsequent Letter of Authorization (LOA) to the Navy to incidentally take marine mammals during the specified activities. NMFS will consider public comments prior to issuing any final rule and making final decisions on the issuance of the requested LOA. Agency responses to public comments will be summarized in the notice of the final decision in the final rule. 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).

DATES:

Comments and information must be received no later than August 30, 2021.

ADDRESSES:

Submit all electronic public comments via the Federal e-Rulemaking Portal. Go to

https://www.regulations.gov

and enter NOAA-NMFS-2021-0064 in the Search box. Click on the “Comment” icon, complete the required fields, and enter or attach your comments.

Instructions:

Comments sent by any other method, to any other address or individual, or received after the end of the comment period, may not be considered by NMFS. All comments received are a part of the public record and will generally be posted for public viewing on

www.regulations.gov

without change. All personal identifying information (

e.g.,

name, address), confidential business information, or otherwise sensitive information submitted voluntarily by the sender will be publicly accessible. NMFS will accept anonymous comments (enter “N/A” in the required fields if you wish to remain anonymous). Attachments to electronic comments will be accepted in Microsoft Word, Excel, or Adobe PDF file formats only.

FOR FURTHER INFORMATION CONTACT:

Stephanie Egger, Office of Protected Resources, NMFS, (301) 427-8401. Electronic copies of the application and supporting documents, as well as a list of the references cited in this document, may be obtained online at:

https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act.

In case of problems accessing these documents, or for anyone who is unable to comment via electronic submission, please call the contact listed above.

SUPPLEMENTARY INFORMATION:

Purpose of Regulatory Action

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

et seq.

), would 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 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) and extends approximately 180 nmi seaward (see Figure 1-1 of the application).

NMFS received an application from the Navy requesting seven-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 and Level B harassment incidental to the Navy's training and testing activities, with no serious injury or mortality expected or proposed for authorization.

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 Preliminary 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 seven years. Prior to this amendment, all incidental take rules under section 101(a)(5)(A) were limited to five 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 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 seven-year period beginning October 2021 through October 2028. 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. We reviewed and considered all comments and information received on the NOR in development of this proposed rule.

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 proposed activities will not include any 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 proposed 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 2020 PMSR DEIS/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 IHAs (84 FR 28462, June 19, 2019; 85 FR 38863, June 29, 2020) 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 proposed 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 proposed regulations would cover training and testing activities that would occur for a seven-year period beginning October 2021.

Description of the Specified Activity

The Navy requests authorization to take marine mammals incidental to conducting training and testing activities. 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 2020 PMSR Draft EIS/OEIS (DEIS/OEIS) (U.S. Department of the Navy, 2020) 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 would occur at any time during the seven-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 Proposed Mitigation Measures section). The proposed amount of training and testing activities are described in the Detailed Description of the Specified Activities section (Table 3).

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 (Figure 1). 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 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 (SUA) and the ocean Operating Areas. Additionally, the Navy is proposing launch activities on San Nicolas Island (SNI), California, for testing and training activities associated with operations within the PMSR Study Area. SNI is one

of the Channel Islands in the PMSR Study Area.

Special Use Airspace

The SUA is airspace designated wherein activities must be confined because of their nature, or wherein limitations are imposed upon aircraft operations that are not a part of those activities, or both. SUA consists of both controlled and uncontrolled airspace and has defined dimensions. Flight and other activities for non-participating aircraft are restricted or prohibited for safety or security reasons. The majority of SUA is established for military flight activities and, with the exception of prohibited areas, may be used for commercial or general aviation when not reserved for military activities. Two area components of the PMSR SUA:

Warning Areas—A Warning Area is airspace of defined dimensions, extending from 3 nmi outward from the coast that contains activity that may be hazardous to non-participating aircraft. Warning areas are established to contain a variety of hazardous aircraft and non-aircraft activities, such as aerial gunnery, air and surface missile firings, bombing, aircraft carrier operations, surface and subsurface operations, and naval gunfire. The 11 Warning Areas within the PMSR include W-532N, W-532E, W-532S; W-537; W-289N, W-289 S, W-289W, W-289E; W-292W, W-292E; and W-412 (see Figure 1).

Restricted Areas—restricted areas are a type of SUA within which the flight of aircraft, while not wholly prohibited, is subject to restriction.

Ocean Operating Areas

The PMSR-controlled sea space (Ocean Operating Areas) parallels the California coast for approximately 225 nmi and extends approximately 180 nmi seaward, aligning with the PMSR Warning Area airspace (Figure 1). The controlled sea space areas consist of the following:

Surface Danger Zones—A danger zone is a defined water area used for target practice, bombing, rocket firing, or other especially hazardous military activities.

Restricted Area—A restricted area is a defined water area for the purpose of prohibiting or limiting public access to the area.

Additional detail can be found in Chapter 2 of the Navy's rulemaking/LOA application.

BILLING CODE 3510-22-P

EP16JY21.002

BILLING CODE 3510-22-C

Overview of Training and Testing Within the PMSR Study Area

The Navy describes and analyzes the effects of its activities within the 2020 PMSR DEIS/OEIS. In its assessment, the Navy concluded that at-surface and near-surface explosive detonations were the stressors that would result in impacts on marine mammals that could rise to the level of harassment as defined under the MMPA. Therefore, the Navy's rulemaking/LOA application provides the Navy's assessment of potential effects from these stressors in terms of various warfare mission areas in which they will be conducted.

Primary Mission Areas

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. Within those three primary mission areas, there are more specific categories or activity scenarios that reflect testing and training activities, as listed below: 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). 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 2020 PMSR DEIS/OEIS and summarized here.

Air warfare

—The mission of air warfare is to destroy or reduce enemy air and missile threats (including unmanned airborne threats) and serves two purposes: To protect U.S. forces from attacks from the air and to gain air superiority. Air warfare provides U.S. forces with adequate attack warnings, while denying hostile forces the ability to gather intelligence about U.S. forces.

Aircraft conduct air warfare through radar search, detection, identification,

and engagement of airborne threats. Surface ships conduct air warfare through an array of modern anti-aircraft weapon systems such as aircraft-detecting radar, naval guns linked to radar-directed fire-control systems, surface-to-air missile systems, and radar-controlled guns for close-in point defense.

Testing of air warfare systems is required to ensure the equipment is fully functional under the conditions in which it will be used. Tests may be conducted on radar and other early-warning detection and tracking systems, new guns or gun rounds, and missiles. Testing of these systems may be conducted on new ships and aircraft, and on existing ships and aircraft following maintenance, repair, or modification. For some systems, tests are conducted periodically to assess operability. Additionally, tests may be conducted in support of scientific research to assess new and emerging technologies. Air-to-air scenarios involve the employment of an airborne weapon system against airborne targets. Missiles are fired from a fighter aircraft for both testing and training events. Surface-to-air scenarios evaluate the overall weapon system performance, warhead effectiveness, and software/hardware modifications or upgrades of ground-based and ship-based weapons systems. Missiles are fired from a ship or a land-based launcher against a variety of supersonic and subsonic airborne targets.

Electronic Warfare

—The mission of electronic warfare is to degrade the enemy's ability to use electronic systems, such as communication systems and radar, and to confuse or deny them the ability to defend their forces and assets. Electronic warfare is also used to detect enemy threats and counter their attempts to degrade the electronic capabilities of the Navy. Typical electronic warfare activities include threat avoidance training, signals analysis for intelligence purposes, and use of airborne and surface electronic jamming devices (that block or interfere with other devices) to defeat tracking, navigation, and communications systems. Testing of electronic warfare systems is conducted to improve the capabilities of systems and ensure compatibility with new systems. Testing involves the use of aircraft, surface ships, and submarine crews to evaluate the effectiveness of electronic systems. Similar to training activities, typical electronic warfare testing activities include the use of airborne and surface electronic jamming devices (including testing chaff and flares; see Appendix A (

PMSR Scenario Descriptions

) of the 2020 PMSR DEIS/OEIS for a description of these devices) to defeat tracking and communications systems.

Surface Warfare

—The mission of surface warfare is to obtain control of sea space from which naval forces may operate, and entails offensive action against other surface, subsurface, and air targets while also defending against enemy forces. In surface warfare, aircraft use guns, air-launched cruise missiles, or other precision-guided munitions; ships employ naval guns, and surface-to-surface missiles; and submarines attack surface ships using submarine-launched, anti-ship cruise missiles. Surface warfare training includes surface-to-surface gunnery and missile exercises, air-to-surface gunnery and missile exercises, and submarine missile launch activities, and other munitions against surface targets. Testing of weapons used in surface warfare is conducted to develop new technologies and to assess weapon performance and operability with new systems, such as unmanned systems. Tests include various air-to-surface guns and missiles, surface-to-surface guns and missiles, and bombing tests. Testing activities may be integrated into training activities to test aircraft or aircraft systems in the delivery of munitions on a surface target. In most cases the tested systems are used in the same manner in which they are used for Fleet training activities. Air-to-surface tests evaluate the integration of a missile or other weapons system into Department of Defense aircraft, or the performance of the missile/system itself. Missiles are fired from an aircraft against a variety of mobile seaborne targets and fixed aim points.

Summary Testing

—Research, Development, Acquisition, Testing, and Evaluation of new technologies by the U.S. Department of Defense occurs continually to ensure that the U.S. military can counter new and anticipated threats. All new Navy systems and related equipment must be tested to ensure proper functioning before delivery to the Fleets for use. The PMSR Study Area is the Navy's primary ocean testing area for guided missiles and related ordnance. Test operations on the PMSR Study Area are conducted under highly controlled conditions, allowing for the collection of empirical data to evaluate the performance of a weapon system or subsystem. Testing conducted in the PMSR Study Area is important for maintaining readiness. Two of the U.S. Navy's Systems Commands, Naval Sea Systems Command (NAVSEA) and Naval Air Systems Command (NAVAIR), sponsor the majority of the testing within the PMSR Study Area. NAVSEA's five affiliated Program Executive Offices (PEOs) oversee over a dozen Program Manager, Sea offices that sponsor testing activities within the PMSR Study Area. NAVAIR's four affiliated PEOs, along with NAVAIR Headquarters-managed programs, oversee approximately 20 Program Managers and Air offices that also sponsor testing activities at PMSR.

Target and Missile Launches on SNI

—The Navy 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. The missiles or targets are launched from one of several fixed locations on the western end of SNI. 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 above sea level. The Point Mugu airfield on the mainland, the airfield on SNI, and the target sites in the PMSR will be a routine part of launch operations.

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 proposed 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 2020 PMSR DEIS/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 & 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 (U.S. Department of the 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 proposed activities do not include explosive munitions used underwater. Missiles, bombs, and projectiles that detonate at or near (within 10 m 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 would 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. Vessel strikes from commercial, recreational, and military vessels are known to seriously injure and occasionally kill cetaceans (Abramson

et al.,

2011; Berman-Kowalewski

et al.,

2010; Calambokidis, 2012; Douglas

et al.,

2008; Laggner, 2009; Lammers

et al.,

2003; Van der Hoop

et al.,

2012; Van der Hoop

et al.,

2013), although reviews of the literature on ship strikes mainly involve collisions between commercial vessels and whales (Jensen and Silber, 2003; Laist

et al.,

2001). Vessel speed, size, and mass are all important factors in determining both the potential likelihood and impacts of a vessel strike to marine mammals (Conn and Silber, 2013; Gende

et al.,

2011; Silber

et al.,

2010; Vanderlaan and Taggart, 2007; Wiley

et al.,

2016). For large vessels, speed and angle of approach can influence the severity of a strike.

The number of Navy vessels in the PMSR Study Area at any given time varies and is dependent on scheduled testing and training requirements. Most activities include either one or two vessels and may last from a few hours to two weeks. Vessel movement as part of the proposed activities would be widely dispersed throughout the PMSR Study Area. Vessels used include ships (

e.g.,

aircraft carriers, surface combatants), support craft, and submarines. Vessel size ranges from 15 ft to over 1,000 ft, and vessels transit at speeds that are optimal for fuel conservation or to meet operational requirements. In comparison, commercial ship size can range from very large oil tankers that are over 1,000 ft in length to the smaller general cargo ships with lengths that can be under 300 ft. Large Navy ships (greater than 18 m in length) generally operate at average speeds of 10-15 knots, and submarines generally operate at speeds in the range of 8-13 knots. Small Navy craft (for purposes of this discussion, less than 18 m in length), which are all support craft, have much more variable speeds (0-50+ knots, dependent on the mission). While these speeds are averages that are representative of most events, some vessels need to operate outside of these parameters. For example, to produce the required relative wind speed over the flight deck, an aircraft carrier engaged in flight operations must adjust its speed through the water accordingly. Also, there are other instances, such as launch and recovery of a small rigid-hull inflatable boat, or retrieval of a target when vessels would be dead in the water, or moving slowly ahead to maintain steerage. There are a few specific testing and training events that include high-speed requirements for certain systems for which vessels would operate at higher speeds.

Refer to Chapter 3,

Affected Environment and Environmental Consequences

of the 2020 PMSR DEIS/OEIS for additional details on vessel use and movement in the PMSR Study Area.

Detailed Description of the Specified Activities

Proposed Training and Testing Activities

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

The proposed 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 proposed 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 Proposed Activities in the PMSR Study Area

[Inclusive of SNI launches]

Activity

Activity sub category

Proposed

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 would not exceed what is proposed in Table 1 above. Proposed 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 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 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 proposed activities are provided in Table 2 for the proposed activities in the PMSR Study Area. Table 2 describes the maximum number of explosives that could be used in any year under the proposed training and testing activities. Under the proposed activities, bin use could vary annually (but would not exceed the maximum), and the seven-year totals for the proposed 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 Seven-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

proposed

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 Proposed Action is a result of a proposed increase in Combat Systems Ship Qualification Trials as discussed in Section 2.2.1 (Current and Proposed Activities) of the 2020 PMSR DSEIS/OEIS.

The explosive energy released by detonations in air has been well studied, and basic methods are available to estimate the explosive energy exposure with distance from the detonation (

e.g.,

U.S. Department of the Navy, 1975). In air, the propagation of impulsive noise from an explosion is highly influenced by atmospheric conditions, including temperature and wind. While basic estimation methods do not consider the unique environmental conditions that

may be present on a given day, they allow for approximation of explosive energy propagation under neutral atmospheric conditions. Explosions that occur during air warfare would 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 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

Missiles can be propelled by either liquid-fueled or solid-fueled rocket engines; however, solid fuel is preferred for military uses. Such engines commonly propel tactical guided missiles (

i.e.,

missiles intended for use within the immediate area) toward their targets at twice the speed of sound. Cruise or ballistic missiles are designed to strike targets far beyond the immediate area, and are therefore also known as strategic missiles. Cruise missiles are jet-propelled at subsonic speeds throughout their flights, while ballistic missiles are rocket-powered only in the initial (boost) phase of flight, after which they follow an arcing trajectory to the target. As gravity pulls the ballistic warhead back to Earth, speeds of several times the speed of sound are reached. Ballistic missiles are most often categorized as short-range, medium-range, intermediate-range, and intercontinental ballistic missiles. Missile weights range between 54-2,900 kilograms (kg), but total weight is dependent on fuel or boosters.

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 proposed 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

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.

The following descriptions are representative of some of the types of targets and missiles typically launched from SNI. While this list is not inclusive of all potential missiles and targets that could be launched annually, the descriptions and the sound profiles are representative of the diversity of the types of missiles and targets typically launched. For information on the sound levels these missiles produce please refer to Section 1.2 of the application.

GQM-163A “Coyote”

—The Coyote, designated GQM-163A, is an expendable Supersonic Sea-Skimming Target (SSST) powered by a ducted-rocket ramjet. This missile is designed to provide a ground-launched, aerial target system to simulate a supersonic, sea-skimming Anti-Ship Cruise missile threat. Coyote launches are expected to be the primary large missile launched from SNI over the next several years. Coyotes are launched from previously installed launchers at the inland location (Alpha Launch Complex) on SNI.

Standard Missile (SM-2, SM-3, SM-6)

—The Standard family of missiles consists of a range of air defense missiles including supersonic, medium, and extended range surface-to-air and surface-to-surface missiles. The Standard Missile 3 Block IIA (SM-3) is a ship-based missile system used to intercept short- to intermediate-range ballistic missiles as a part of the Aegis Ballistic Missile Defense System. Although primarily designed as an antiballistic missile defensive weapon, the SM-3 has also been employed in an anti-satellite capacity against a satellite at the lower end of low Earth orbit. Similarly, the SM-6 is a vertically launched, extended range missile compatible with the Aegis Weapon System to be used against extended range threats. The SM-6 Block I/IA combines the tested legacy of the SM-2 propulsion system and warhead with an active radio frequency seeker modified from the AIM-120 Advanced Medium Range Air-to-Air Missile. The new features allow for over-the-horizon engagements, enhanced capability at extended ranges and increased firepower. To date, only the SM-3 has been launched from SNI.

Other Missiles That May Be Used During Launch Events

—The Navy may also launch other missiles to simulate various types of threat missiles and aircraft and to test other systems. For example, Tactical Tomahawks were launched from Building 807 Launch Complex in 2018 and 2019. Under this proposed rule, missiles launched from SNI would have sound source levels the same or lower than missiles described above or previously launched from the island.

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 two weeks. Vessel movement as part of the proposed activities would 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 nautical miles (nmi) 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

Proposed 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

Additional details on Navy at-sea vessel movement are provided in the 2020 PMSR DEIS/OEIS.

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. Navy publishes or broadcasts standard operating procedures via numerous naval instructions and manuals, including but not limited to the following:

• Ship, submarine, and aircraft safety manuals;

• Ship, submarine, and aircraft standard operating manuals;

• Fleet Area Control and Surveillance Facility range operating instructions;

• Fleet exercise publications and instruction;

• Naval Air Warfare Center Weapons Division (NAWCWD) and Naval Sea Systems Command test range safety and standard operating instructions;

• Navy instrumented range operating procedures;

• Naval shipyard sea trial agendas;

• Research, development, test, and evaluation plans;

• Naval gunfire safety instructions;

• Navy planned maintenance system instructions and requirements;

• Federal Aviation Administration regulations;

• International Regulations for Preventing Collisions at Sea;

• Range safety standard operating procedures and instructions for explosive munitions; and

• Ammunition and Explosive Operations standard operating procedures.

Because standard operating procedures are essential to safety and mission success, the Navy considers them to be part of the proposed Specified Activities, and has included them in the environmental analysis (see Chapter 3,

Affected Environment and Environmental Consequences,

of the 2020 PMSR DSEIS/OEIS for further details).

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

Marine mammal species that have the potential to occur in the PMSR Study Area are presented in Table 5 along with an abundance estimate, an associated coefficient of variation value, and best and minimum abundance estimates. The Navy requests authorization to take individuals of marine mammal species by Level A and Level B harassment incidental to training and testing activities from detonations of explosives occurring at or near the surface and launch activities on SNI (Table 5).

Information on the status, distribution, abundance, population trends, habitat, and ecology of marine mammals in the PSMR Study Area also may be found in Section 4 of the Navy's rulemaking/LOA application. NMFS reviewed this information and found it to be accurate and complete. Additional information on the general biology and ecology of marine mammals is included in the 2020 PMSR DEIS/OEIS. Table 5 incorporates data from the U.S. Pacific and the Alaska Marine Mammal Stock Assessment Reports (SARs; Carretta

et al.,

2019; Muto

et al.,

2019) and the most recent revised data in the draft SARs (see

https://www.fisheries.noaa.gov/national/marine-mammal-protection/draft-marine-mammal-stock-assessment-reports

). Table 5 also incorporates the best available science, including monitoring data from the Navy's marine mammal research efforts.

Species Not Included in the Analysis

The species carried forward for analysis (and described in Table 5 below) are those likely to be found in the PMSR Study Area based on the most recent data available, and do not include species that may have once inhabited or transited the area but have not been sighted in recent years (

e.g.,

species which were extirpated from factors such as 19th and 20th century commercial exploitation). Several species that may be present in the northwest Pacific Ocean have a low probability of presence in the PMSR Study Area. These species are considered extralimital (not anticipated to occur in the Study Area) or rare (occur in the Study Area sporadically, but sightings are rare). Species unlikely to be present in the PMSR Study Area or that are rare include the North Pacific right whale (

Eubalaena japonica

), rough-toothed dolphin (

Steno bredanensis

), and Steller sea lion

(

Eumetopias jubatus

), and these species have all been excluded from subsequent analysis for the reasons described below. There have been only four sightings, each of a single Northern Pacific right whale, in Southern California waters over approximately the last 30 years (in 1988, 1990, 1992, and 2017) (Brownell

et al.,

2001; Carretta

et al.,

1994; National Marine Fisheries Service, 2017b; WorldNow, 2017). Sightings off California are rare, and historically, even during the period of U.S. West Coast whaling through the 1800s, right whales were considered uncommon to rare off California (Reeves and Smith, 2010; Scammon, 1874). The range of the rough-toothed dolphin is known to occasionally include the Southern California coast during periods of warmer ocean temperatures, but there is no recognized stock for the U.S. West Coast (Carretta

et al.,

2019c). Several strandings were documented for this species in central and Southern California between 1977 and 2002 (Zagzebski

et al.,

2006), but this species has not been observed during seven systematic ship surveys from 1991 to 2014 off the U.S. West Coast (Barlow, 2016). During 16 quarterly ship surveys off Southern California from 2004 to 2008, there was one encounter with a group of nine rough-toothed dolphins, which was considered an extralimital occurrence (Douglas

et al.,

2014). Steller sea lions range along the north Pacific from northern Japan to California (Perrin

et al.,

2009b), with centers of abundance and distribution in the Gulf of Alaska and Aleutian Islands (Muto et al., 2019). San Miguel Island and Santa Rosa Island were, in the past, the southernmost rookeries and haulouts for the Steller sea lions, but their range contracted northward in the 20th century, and now Año Nuevo Island off central California is currently the southernmost rookery (Muto

et al.,

2019; National Marine Fisheries Service, 2008; Pitcher

et al.,

2007). Steller sea lions pups were known to be born at San Miguel Island up until 1981 (National Marine Fisheries Service, 2008; Pitcher

et al.,

2007), and so, as the population continues to increase, it is anticipated that the Steller sea lions may re-establish a breeding colony on San Miguel Island in the future. In the Channel Islands and vicinity, despite the species' general absence from the area, a consistent but small number of Steller sea lions (one to two individuals at a time) have been sighted in recent years. Aerial surveys for pinnipeds in the Channel Islands from 2011 to 2015 encountered a single Steller sea lion at SNI in 2013 (Lowry

et al.,

2017). NMFS agrees with the Navy's assessment that these species are unlikely to occur in the PMSR Study Area and they are not discussed further.

Southern sea otter (

Enhydra lutris neris

) occurs nearshore off the coast of central California, ranging from Half Moon Bay in the north to Point Conception and at SNI (Tinker

et al.,

2006; Tinker and Hatfield, 2016; U.S. Geological Survey, 2014). Southern sea otters are managed by the U.S. Fish and Wildlife Service and therefore are not discussed further.

Table 5—Marine Mammal Occurrence Within the PMSR Study Area

Common name

Scientific name

1

Stock

Status

MMPA

ESA

Stock abundance

(CV)/N

min

; most recent abundance survey

2

PBR

3

Annual M/SI

4

Blue whale

Balaenoptera musculus

Eastern North Pacific

Depleted

Endangered

1,496 (0.44)/1,051; 2014

1.2

≥19.4

Bryde's whale

Balaenoptera brydei/edeni

Eastern Tropical Pacific

unk; na

unk

unk

Fin whale

Balaenoptera physalus

California, Oregon, and Washington

Depleted

Endangered

9,029 (0.12)/8,127; 2014

81

≥43.7

Gray whale

Eschrichtius robustus

Eastern North Pacific

26,960 (0.05)/25,849; 2016

801

131

Western North Pacific

Depleted

Endangered

290 (na)/271; 2016

0.12

unk

Humpback whale

Megaptera novaeangliae

California, Oregon, Washington

Depleted

Threatened/Endangered

1

2,900 (0.05)/2,784; 2019

16.7

≥42.1

Minke whale

Balaenoptera acutorostrata

California, Oregon, and Washington

636 (0.72)/369; 2014

3.5

≥1.3

Sei whale

Balaenoptera borealis

Eastern North Pacific

Depleted

Endangered

519 (0.4)/374; 2014

0.75

≥0.2

Baird's beaked whale

Berardius bairdii

California, Oregon, and Washington

2,697 (0.6)/1,633; 2014

16

0

Common Bottlenose dolphin

Tursiops truncatus

California Coastal

453 (0.06)/346; 2011

2.7

≥2.0

California, Oregon, and Washington Offshore

1,924 (0.54)/1,255; 2014

11

≥1.6

Cuvier's beaked whale

Ziphius cavirostris

California, Oregon, and Washington

3,274 (0.67)/2,059; 2014

21

<0.1

Dall's porpoise

Phocoenoides dalli

California, Oregon, and Washington

25,750 (0.45)/17,954; 2014

172

0.3

Dwarf sperm whale

Kogia sima

California, Oregon, and Washington

unk; 2014

und

0

Harbor Porpoise

Phocoena phocoena

Morro Bay

2,917

5

(0.41)/1,384; 2012

5

66

5

≥0.4

Killer whale

Orcinus orca

Eastern North Pacific Offshore

300 (0.10)/276; 2012

2.8

0

Eastern North Pacific Transient/West Coast Transient

6

349 na/349; 2018

3.5

0.4

Long-beaked common dolphin

Delphinus capensis

California

101,305 (0.49)/68,432; 2014

657

≥35.4

Mesoplodont beaked whales

7

Mesoplodon spp

California, Oregon, and Washington

3,044 (0.54)/1,967; 2014

20

0.1

Northern right whale dolphin

Lissodelphis borealis

California, Oregon, and Washington

26,556 (0.44)/18,608; 2014

179

3.8

Pacific white-sided dolphin

Lagenorhynchus obliquidens

California, Oregon, and Washington

26,814 (0.28)/21,195; 2014

191

7.5

Pygmy sperm whale

Kogia breviceps

California, Oregon, and Washington

4,111 (1.12)/1,924; 2014

19

0

Risso's dolphins

Grampus griseus

California, Oregon, and Washington

6,336 (0.32)/4,817; 2014

46

≥3.7

Short-beaked common dolphin

Delphinus delphis

California, Oregon, and Washington

969,861 (0.17)/839,325; 2014

8,393

≥40

Short-finned pilot whale

Globicephala macrorhynchus

California, Oregon, and Washington

836 (0.79)/466; 2014

4.5

1.2

Sperm whale

Physeter macrocephalus

California, Oregon, and Washington

Depleted

Endangered

1,997 (0.57)/1,270; 2014

2.5

0.6

Striped dolphin

Stenella coeruleoalba

California, Oregon, and Washington

29,211 (0.20)/24,782; 2014

238

≥0.8

Harbor seal

Phoca vitulina

California

30,968 na/27,348; 2012

1,641

43

Northern elephant seal

Mirounga angustirostris

California

179,000 na/81,368; 2010

4,882

8.8

California sea lion

Zalophus californianus

U.S. Stock

257,606 na/233,515; 2014

14,011

≥321

Northern fur seal

Callorhinus ursinus

California

14,050 na/7,524; 2013

451

1.8

Guadalupe fur seal

Arctocephalus townsendi

Mexico to California

Depleted

Threatened

34,187 unk/31,109; 2013

1,602

≥3.8

1

Taxonomy follows Committee on Taxonomy (2018).

2

CV is coefficient of variation; N

min

is the minimum estimate of stock abundance. The most recent abundance survey that is reflected in the abundance estimate is presented; there may be more recent surveys that have not yet been incorporated into the estimate.

3

PBR is the Potential biological removal, defined by the MMPA as the maximum number of animals, not including natural mortalities, that may be removed from a marine mammal stock while allowing that stock to reach or maintain its optimum sustainable population size (OSP).

4

These values, found in NMFS's SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined (

e.g.,

commercial fisheries, subsistence hunting, ship strike). Annual M/SI often cannot be determined precisely and is in some cases presented as a range.

5

The abundance number as presented is from the “fine-scale transects” as documented in Forney

et al.

(2014). PBR and M/SI are from draft 2020 SAR for the Pacific (Carretta

et al.,

2020).

6

This stock is mentioned briefly in the Pacific Stock Assessment Report and referred to as the “Eastern North Pacific Transient” stock, however, the Alaska Stock Assessment Report contains assessments of all transient killer whale stocks in the Pacific, and the Alaska Stock Assessment Report refers to this same stock as the “West Coast Transient” stock (Muto

et al.,

2019).

7

The six

Mesoplodont

beaked whale species off California are

M. densirostris, M. carlhubbsi, M. ginkgodens, M. perrini, M. peruvianus, M. stejnegeri.

Notes:

na = not available; unk = unknown ; und = undetermined or not provided in the draft 2020 SAR for the Pacific (Carretta

et al.,

2020) (Carretta

et al.,

2019b).

Further, after Navy completed their modeling analysis, 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 agrees with the Navy's analysis; therefore, these species are excluded from further analysis.

Below, we include additional information about the marine mammals in the area of the Specified Activities that informs our analysis, such as identifying known areas of important habitat or behaviors, or where Unusual Mortality Events (UME) have been designated.

Critical Habitat

The statutory definition of occupied critical habitat refers to “physical or biological features essential to the conservation of the species,” but the ESA does not specifically define or further describe these features. ESA-implementing regulations at 50 CFR 424.02 (as amended, 84 FR 45020; August 27, 2019), however, define such features as follows: The features that occur in specific areas and that are essential to support the life-history needs of the species, including but not limited to, water characteristics, soil type, geological features, sites, prey, vegetation, symbiotic species, or other features. A feature may be a single habitat characteristic, or a more complex combination of habitat characteristics. Features may include habitat characteristics that support ephemeral or dynamic habitat conditions. Features may also be expressed in terms relating to principles of conservation biology, such as patch size, distribution distances, and connectivity.

On April 21, 2021, NMFS issued a final rule to designate critical habitat in nearshore waters of the North Pacific Ocean for the endangered Central America DPS and the threatened Mexico DPS of humpback whales (86 FR 21082). Critical habitat for the Central America DPS and Mexico DPS was established within the California Current Ecosystem (CCE) off the coasts of California, Oregon, and Washington, representing areas of key foraging habitat. Prey of sufficient quality, abundance, and accessibility within humpback whale feeding areas to support feeding and population growth is identified an essential feature to the conservation of these whales. Because humpback whales only rarely feed on breeding grounds and during migrations, humpback whales must have access to adequate prey resources within their feeding areas to build up their fat stores and meet the nutritional and energy demands associated with individual survival, growth, reproduction, lactation, seasonal migrations, and other normal life functions. Given that each of three humpback whale DPSs very clearly rely on the feeding areas while within U.S. waters, prey has been identified as a biological feature that is essential to the conservation of the whales. The prey essential feature was specifically defined as follows: Prey species, primarily euphausiids and small pelagic schooling fishes of

sufficient quality, abundance, and accessibility within humpback whale feeding areas to support feeding and population growth.

NMFS considered 19 units of habitat as critical habitat for the listed humpback whale DPSs. There is overlap between the PMSR Study Area and portions of the habitat designated Units 17 and 18 (see Figure 3.7-5 of the 2020 PMSR DEIS/OEIS) in the final critical habitat rule (86 FR 21082), which are described below.

Unit 17, referred to as the “Central California Coast Area,” extends from 36°00′ N to a southern boundary at 34°30′ N. The nearshore boundary is defined by the 30-m isobath, and the seaward boundary is drawn along the 3,700-m isobath. This unit includes waters off of southern Monterey County, and San Luis Obispo and Santa Barbara Counties. Unit 17 covers 6,697 nmi

2

of marine habitat. This unit encompasses Morro Bay to Point Sal Biologically Important Area (BIA; see next section) and typically supports high density feeding aggregations of humpback whales from April to November (Calambokidis

et al.

2015). Based on acoustic survey data collected during 2004-2009, large krill hotspots, ranging from 700 km

2

to 2,100 km

2

, occur off Big Sur, San Luis Obispo, and Point Sal (Santora

et al.

2011). Hotspots with persistent, heightened abundance of krill were also reported in this unit in association with bathymetric submarine canyons (Santora

et al.

2018). This is the northernmost portion of humpback whale critical habitat that overlaps with the PMSR Study Area.

Unit 18, referred to as the “Channel Islands Area,” extends from a northern boundary at 34°30′ N to a boundary line that extends from Oxnard, CA seaward to the 3,700-m isobath, along which the offshore boundary is drawn. The 50-m isobath forms the shoreward boundary. This unit includes waters off of Santa Barbara and Ventura counties. This unit covers 9,799 nmi

2

of marine habitat. This unit encompasses the Santa Barbara Channel-San Miguel BIA, which supports high density feeding aggregations of humpback whales during March through September (Calambokidis

et al.

2015). Based on acoustic survey data collected during 2004-2009, a krill hotspot of about 780 km

2

has been documented off Point Conception (Santora

et al.

2011). Some additional krill hotspots have also been observed in this unit in association with bathymetric submarine canyons (Santora

et al.

2018). Coastal waters managed by the Navy, as addressed within the Point Mugu Integrated Natural Resources Management Plan (INRMP) and SNI INRMP, are not included in the proposed designation as these areas were determined by NMFS to be ineligible for designation as critical habitat under section 4(a)(3)(B)(i) of the ESA (84 FR 54354; October 9, 2019).The Navy does not anticipate national security impacts resulting from critical habitat designation in the portion of Region/Unit 18 that overlaps with the PMSR Study Area.

Biologically Important Areas

Biologically Important Areas (BIAs) include areas of known importance for reproduction, feeding, or migration, or areas where small and resident populations are known to occur (Van Parijs, 2015). Unlike ESA critical habitat, these areas are not formally designated pursuant to any statute or law, but are a compilation of the best available science intended to inform impact and mitigation analyses. An interactive map of the BIAs may be found here:

https://cetsound.noaa.gov/biologically-important-area-map.

BIAs off the West Coast of the continental United States with the potential to overlap portions of the PMSR Study Area include the following feeding and migration areas for blue whales, gray whales, and humpback whales and are described in further detail below (Calambokidis

et al.,

2015).

Blue Whale Feeding BIAs

Three blue whale feeding BIAs overlap with the PMSR Study Area (see Figure 3.7-2 of the 2020 PMSR DEIS/OEIS). The Point Conception/Arguello to Point Sal Feeding Area and Santa Barbara Channel and San Miguel Feeding Area have large portions within the PMSR Study Area, 87 and 61 percent respectively. The San Nicolas Island Feeding Area is entirely within the PMSR Study Area (Calambokidis

et al.,

2015a). Feeding by blue whales occurs from June through October in these BIAs (Calambokidis

et al.,

2015a).

Gray Whale Migration BIAs

Four gray whale migration BIAs overlap with the PMSR Study Area (see Figure 3.7-3 of the 2020 PMSR DEIS/OEIS). The northward migration of the Eastern North Pacific stock of gray whales to the feeding grounds in Arctic waters, Alaska, the Pacific Northwest, and Northern California occurs in two phases: Northbound Phase A and Northbound Phase B (Calambokidis

et al.,

2015). Northbound Phase A migration BIA consists mainly of adults and juveniles that lead the beginning of the north-bound migration from late January through July, peaking in April through July. Newly pregnant females go first to maximize feeding time, followed by adult females and males, and then juveniles (Jones and Swartz, 2009). The Northbound Phase B migration BIA consists primarily of cow-calf pairs that begin their northward migration later (March through July), as they remain on the reproductive grounds longer to allow calves to strengthen and rapidly increase in size before the northward migration (Jones and Swartz, 2009; Urban-Ramirez

et al.,

2003). The Potential presence migration BIA (January through July; October through December) and the Southbound—All migration BIA (October through March) routes pass through the waters of the PMSR Study Area.

Humpback Whale Feeding BIAs

Two humpback whale feeding areas overlap with the PMSR Study Area (Calambokidis

et al.,

2015) (see Figure 3.7-4 of the 2020 PMSR DEIS/OEIS). These BIAs include the Morro Bay to Point Sal feeding area (April through November) and the Santa Barbara Channel-San Miguel feeding area (March through September) (Calambokidis

et al.,

2015). The majority of these BIAs overlap with the PMSR Study Area (approximately 75 percent).

National Marine Sanctuaries

Under Title III of the Marine Protection, Research, and Sanctuaries Act of 1972 (also known as the National Marine Sanctuaries Act (NMSA)), NOAA can establish as national marine sanctuaries (NMS), areas of the marine environment with special conservation, recreational, ecological, historical, cultural, archaeological, scientific, educational, or aesthetic qualities. Sanctuary regulations prohibit or regulate activities that could destroy, cause the loss of, or injure sanctuary resources pursuant to the regulations for that sanctuary and other applicable law (15 CFR part 922). NMSs are managed on a site-specific basis, and each sanctuary has site-specific regulations. Most, but not all, sanctuaries have site-specific regulatory exemptions from the prohibitions for certain military activities. Separately, section 304(d) of the NMSA requires Federal agencies to consult with the Office of National Marine Sanctuaries whenever their activities are likely to destroy, cause the loss of, or injure a sanctuary resource.

There are two NMSs managed by the Office of National Marine Sanctuaries within the PMSR Study Area: The Channel Islands NMS and a small portion of the Monterey Bay NMS. The

Channel Islands NMS is an ecosystem-based managed sanctuary consisting of an area of 1,109 nmi

2

around Anacapa Island, Santa Cruz Island, Santa Rosa Island, San Miguel Island, and Santa Barbara Island to the south. It encompasses sensitive habitats (

e.g.,

kelp forest habitat, deep benthic habitat) and includes various shipwrecks and maritime heritage artifacts. The Channel Islands NMS waters and its remote, isolated position at the confluence of two major ocean currents support significant biodiversity of marine mammals, fish, and invertebrates. At least 33 species of cetaceans have been reported in the Channel Islands NMFS region with common species, including: Long-beaked common dolphin, short-beaked common dolphin, Bottlenose dolphin, Pacific white-sided dolphin, Northern right whale dolphin, Risso's dolphin, California gray whale, Blue whale, and Humpback whale. The three species of pinnipeds that are commonly found throughout or in part of the Channel Islands NMS include: California sea lion, Northern elephant seal, and Pacific harbor seal. About 877 nmi

2

, or 79 percent of the Channel Island NMS, occurs within the PMSR Study Area (see Chapter 6 of the 2020 PMSR DEIS/OEIS and Figure 6.1-1). The Monterey Bay NMS is an ecosystem-based managed sanctuary consisting of an area of 4,601 nmi

2

stretching from Marin to Cambria and extending an average of 30 miles from shore. The Monterey Bay NMS contains extensive kelp forests and one of North America's largest underwater canyons and closest-to-shore deep ocean environments. Its diverse marine ecosystem also includes rugged rocky shores, wave-swept sandy beaches and tranquil estuaries. These habitats support a variety of marine life, including 36 species of marine mammals, more than 180 species of seabirds and shorebirds, at least 525 species of fishes, and an abundance of invertebrates and algae. Of the 36 species of marine mammals, six are pinnipeds with California sea lions being the most common, and the remainder are twenty-six species of cetaceans. Only 19 nmi

2

, or less than 1 percent of the Monterey Bay NMS, occurs within the PMSR Study Area (see Chapter 6 of the 2020 PMSR DEIS/OEIS and Figure 6.1-1).

Unusual Mortality Events (UMEs)

An UME is defined under Section 410(6) of the MMPA as a stranding that is unexpected; it involves a significant die-off of any marine mammal population, and demands immediate response. From 1991 to the present, there have been 14 formally recognized UMEs affecting marine mammals in California and involving species under NMFS' jurisdiction. Three UMEs with ongoing or recently closed investigations in the PMSR Study Area that inform our analysis are discussed below. The California sea lion UME in California was closed on May 6, 2020. The Guadalupe fur seal UME in California and the gray whale UME along the west coast of North America are active and involve ongoing investigations.

California Sea Lion UME

From January 2013 through September 2016, a greater than expected number of young malnourished California sea lions (

Zalophus californianus

) stranded along the coast of California. Sea lions stranding from an early age (6-8 months old) through two years of age (hereafter referred to as juveniles) were consistently underweight without other disease processes detected. Of the 8,122 stranded juveniles attributed to the UME, 93 percent stranded alive (n = 7,587, with 3,418 of these released after rehabilitation) and 7 percent (n = 531) stranded dead. Several factors are hypothesized to have impacted the ability of nursing females and young sea lions to acquire adequate nutrition for successful pup rearing and juvenile growth. In late 2012, decreased anchovy and sardine recruitment (CalCOFI data, July 2013) may have led to nutritionally stressed adult females. Biotoxins were present at various times throughout the UME, and while they were not detected in the stranded juvenile sea lions (whose stomachs were empty at the time of stranding), biotoxins may have impacted the adult females' ability to support their dependent pups by affecting their cognitive function (

e.g.,

navigation, behavior towards their offspring). Therefore, the role of biotoxins in this UME, via its possible impact on adult females' ability to support their pups, is unclear. The proposed primary cause of the UME was malnutrition of sea lion pups and yearlings due to ecological factors. These factors included shifts in distribution, abundance and/or quality of sea lion prey items around the Channel Island rookeries during critical sea lion life history events (nursing by adult females, and transitioning from milk to prey by young sea lions). These prey shifts were most likely driven by unusual oceanographic conditions at the time due to the event known as the “Warm Water Blob” and El Niño. This investigation closed on May 6, 2020. Please refer to:

https://www.fisheries.noaa.gov/national/marine-life-distress/2013-2016-california-sea-lion-unusual-mortality-event-california

for more information on this UME.

Guadalupe Fur Seal UME

Increased strandings of Guadalupe fur seals began along the entire coast of California in January 2015 and were eight times higher than the historical average (approximately 10 seals/yr). Strandings have continued since 2015 and remained well above average through 2020. Numbers by year are as follows: 2015 (98), 2016 (76), 2017 (62), 2018 (45), 2019 (116), 2020 (95 as of December 17, 2020). The total number of Guadalupe fur seals stranding in California from January 1, 2015, through December 17, 2020, in the UME is 492. Strandings of Guadalupe fur seals became elevated in the spring of 2019 in Washington and Oregon, and strandings for seals in these two states subsequently (starting from January 1, 2019) have been added to the UME. The current total number of strandings in Washington and Oregon is 133 seals, including 91 in 2019 and 42 in 2020 as of December 17, 2020. Strandings are seasonal and generally peak in April through June of each year. The Guadalupe fur seal strandings involved the stranding of mostly weaned pups and juveniles (1-2 years old), with both live and dead strandings occurring. Current studies of this UME find that the majority of stranded animals experienced primary malnutrition with secondary bacterial and parasitic infections. The California portion of this UME was occurring in the same area where the 2013-2016 California sea lion UME occurred. This investigation is ongoing. Please refer to:

https://www.fisheries.noaa.gov/national/marine-life-distress/2015-2020-guadalupe-fur-seal-unusual-mortality-event-california

for more information on this UME.

Gray Whale UME

Since January 1, 2019, elevated levels of gray whale strandings have occurred along the west coast of North America, from Mexico to Canada. As of December 17, 2020, there have been a total of 385 strandings along the coasts of the United States, Canada, and Mexico, with 201 of those strandings occurring along the U.S. coast. Of the strandings on the U.S. coast, 93 have occurred in Alaska, 47 in Washington, 9 in Oregon, and 52 in California. Partial necropsy examinations conducted on a subset of stranded whales have shown evidence of poor to thin body condition, killer whale predation, and human

interactions. As part of the UME investigation process, NOAA is assembling an independent team of scientists to coordinate with the Working Group on Marine Mammal UMEs to review the data collected, sample stranded whales, and determine the next steps for the investigation. Please refer to:

https://www.fisheries.noaa.gov/national/marine-life-distress/2019-2020-gray-whale-unusual-mortality-event-along-west-coast.

Potential Effects of Specified Activities on Marine Mammals and Their Habitat

This section includes a summary of the ways that components of the specified activity may impact marine mammals and their habitat. The Estimated Take of Marine Mammals section later in this rule includes a quantitative analysis of the number of instances of take that could occur from these activities. The Preliminary Analysis and Negligible Impact Determination section considers the content of this section, the Estimated Take of Marine Mammals section, and the Proposed Mitigation Measures section to draw conclusions regarding the likely impacts of these activities on the reproductive success or survivorship of individuals and whether those impacts on individuals are likely to adversely affect the species through effects on annual rates of recruitment or survival.

The Navy has requested authorization for the take of marine mammals that may occur incidental to training and testing activities in the PMSR Study Area. The Navy analyzed potential impacts to marine mammals from explosive sources, target and missile launches from SNI, and from vessel use in its rulemaking/LOA application. NMFS carefully reviewed the information provided by the Navy along with independently reviewing applicable scientific research and literature and other information to evaluate the potential effects of the Navy's activities on marine mammals.

Other potential impacts to marine mammals from training and testing activities in the PMSR Study Area were analyzed in the 2020 PMSR DEIS/OEIS, in consultation with NMFS as a cooperating agency. In particular, the Navy determined that these activities were unlikely to result in any incidental take from vessel strike or in any serious injury or mortality from explosive detonations (discussed in this section below), and the Navy has not requested authorizations of any such incidental take. NMFS agrees with these determinations by the Navy. Accordingly, in this proposed rule NMFS' analysis focuses on the potential effects on marine mammals from the activity components that may cause the take of marine mammals: Exposure to explosive stressors and launches.

For the purpose of MMPA incidental take authorizations, NMFS' effects assessments serve four primary purposes: (1) To determine whether the specified activities would have a negligible impact on the affected species or stocks of marine mammals (based on whether it is likely that the activities would adversely affect the species or stocks through effects on annual rates of recruitment or survival); (2) to determine whether the specified activities would have an unmitigable adverse impact on the availability of the species or stocks for subsistence uses; (3) to prescribe the permissible methods of taking (

i.e.,

Level B harassment (behavioral disturbance, incurred directly or as a result of temporary threshold shift (TTS)), and Level A harassment (permanent threshold shift (PTS) and non-auditory injury)), including identification of the number and types of take that could occur by harassment, serious injury, or mortality, and to prescribe other means of effecting the least practicable adverse impact on the species or stocks and their habitat (

i.e.,

mitigation measures); and (4) to prescribe requirements pertaining to monitoring and reporting.

Marine mammals may be affected by Navy activities by sensory impairment (permanent and temporary threshold shifts and acoustic masking), physiological responses (particular stress responses), direct behavioral disturbance, or habitat effects. The Estimated Take of Marine Mammals section discusses how the potential effects on marine mammals from the impulsive acoustic sources considered in this rule relate to the MMPA definitions of Level A harassment and Level B harassment, and quantifies those effects that rise to the level of a take. The Preliminary Analysis and Negligible Impact Determination section assesses whether the proposed authorized take would have a negligible impact on the affected species and stocks.

Sections 6, 7, and 9 of the Navy's application include summaries of the ways that components of the specified activity may impact marine mammals and their habitat, including specific discussion of potential effects to marine mammals from noise and other stressors produced through the use explosives detonating at or near the surface and noise from launch events on SNI. We have reviewed the Navy's discussion of potential effects for accuracy and completeness in its application and refer to that information rather than repeating it in full here. Below we include a summary of the potential effects to marine mammals.

Additionally, NMFS has included a comprehensive discussion of the potential effects of similar activities on marine mammals, including specifically from Navy testing and training exercises that use explosives, in other

Federal Register

notices. For additional detail, we refer the reader to these notices; please see, 85 FR 72312 (November 9, 2020) (Navy testing and training, including explosives); 84 FR 28462 (June 12, 2019) (Navy IHA on target and missile launches from SNI); and 79 FR 32678 (June 6, 2014) (Navy previous rule on target and missile launches from SNI), or view documents available online at

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

Below we provide a brief technical background on sound, on the characteristics of certain sound types, and on metrics used in this proposal, as well as a brief overview of the potential effects to marine mammals associated with the Navy's proposed activities. The proposed training and testing exercises have the potential to cause take of marine mammals by exposing them to impulsive noise and pressure waves generated by explosive detonation at or near the surface of the water as well as by impulsive noise target and missile launches from SNI. Exposure to noise or pressure resulting from these detonations and launches could result in non-lethal injury (Level A harassment) or disturbance (Level B harassment). The potential effects of impulsive sound and pressure from the proposed training and testing activities may include one or more of the following: Tolerance, masking, disturbance, hearing threshold shift, and stress responses. In addition, NMFS also considered the potential for harassment from vessels and serious injury and mortality from explosive detonations.

Description of Sound Sources

This section contains a brief technical background on sound, on the characteristics of certain sound types, and on metrics used in this proposal inasmuch as the information is relevant to the specified activity and to a discussion of the potential effects of the specified activity on marine mammals found later in this document. For general information on sound and its interaction with the marine environment, please see,

e.g.,

Au and

Hastings (2008); Richardson

et al.

(1995); Urick (1983).

Sound travels in waves, the basic components of which are frequency, wavelength, velocity, and amplitude. Frequency is the number of pressure waves that pass by a reference point per unit of time and is measured in hertz or cycles per second. Wavelength is the distance between two peaks or corresponding points of a sound wave (length of one cycle). Higher frequency sounds have shorter wavelengths than lower frequency sounds, and typically attenuate (decrease) more rapidly, except in certain cases in shallower water. Amplitude is the height of the sound pressure wave or the “loudness” of a sound and is typically described using the relative unit of the decibel (dB). A sound pressure level (SPL) in dB is described as the ratio between a measured pressure and a reference pressure (for underwater sound, this is 1 microPascal (μPa)), and is a logarithmic unit that accounts for large variations in amplitude. Therefore, a relatively small change in dB corresponds to large changes in sound pressure. The source level (SL) represents the SPL referenced at a distance of 1 m from the source (referenced to 1 μPa), while the received level is the SPL at the listener's position (referenced to 1 μPa).

Root mean square (rms) is the quadratic mean sound pressure over the duration of an impulse. Root mean square is calculated by squaring all of the sound amplitudes, averaging the squares, and then taking the square root of the average (Urick, 1983). Root mean square accounts for both positive and negative values; squaring the pressures makes all values positive so that they may be accounted for in the summation of pressure levels (Hastings and Popper, 2005). This measurement is often used in the context of discussing behavioral effects, in part because behavioral effects, which often result from auditory cues, may be better expressed through averaged units than by peak pressures.

Sound exposure level (SEL; represented as dB re 1 μPa

2

-s) represents the total energy in a stated frequency band over a stated time interval or event and considers both intensity and duration of exposure. The per-pulse SEL is calculated over the time window containing the entire pulse (

i.e.,

100 percent of the acoustic energy). SEL is a cumulative metric; it can be accumulated over a single pulse, or calculated over periods containing multiple pulses. Cumulative SEL represents the total energy accumulated by a receiver over a defined time window or during an event. Peak sound pressure (also referred to as zero-to-peak sound pressure or 0-pk) is the maximum instantaneous sound pressure measurable in the water at a specified distance from the source and is represented in the same units as the rms sound pressure. When underwater objects vibrate or activity occurs, sound-pressure waves are created. These waves alternately compress and decompress the water as the sound wave travels. Underwater sound waves radiate in a manner similar to ripples on the surface of a pond and may be either directed in a beam or beams or may radiate in all directions (omnidirectional sources), as is the case for sound produced by the pile driving activity considered here. The compressions and decompressions associated with sound waves are detected as changes in pressure by aquatic life and man-made sound receptors such as hydrophones.

Even in the absence of sound from the specified activity, the underwater environment is typically loud due to ambient sound, which is defined as environmental background sound levels lacking a single source or point (Richardson

et al.,

1995). The sound level of a region is defined by the total acoustical energy being generated by known and unknown sources. These sources may include physical (

e.g.,

wind and waves, earthquakes, ice, atmospheric sound), biological (

e.g.,

sounds produced by marine mammals, fish, and invertebrates), and anthropogenic (

e.g.,

vessels, dredging, construction) sound. A number of sources contribute to ambient sound, including wind and waves, which are a main source of naturally occurring ambient sound for frequencies between 200 Hz and 50 kHz (Mitson, 1995). In general, ambient sound levels tend to increase with increasing wind speed and wave height. Precipitation can become an important component of total sound at frequencies above 500 Hz, and possibly down to 100 Hz during quiet times. Marine mammals can contribute significantly to ambient sound levels, as can some fish and snapping shrimp. The frequency band for biological contributions is from approximately 12 Hz to over 100 kHz. Sources of ambient sound related to human activity include transportation (surface vessels), dredging and construction, oil and gas drilling and production, geophysical surveys, sonar, and explosions. Vessel noise typically dominates the total ambient sound for frequencies between 20 and 300 Hz. In general, the frequencies of anthropogenic sounds are below 1 kHz and, if higher frequency sound levels are created, they attenuate rapidly. The sum of the various natural and anthropogenic sound sources that comprise ambient sound at any given location and time depends not only on the source levels (as determined by current weather conditions and levels of biological and human activity) but also on the ability of sound to propagate through the environment. In turn, sound propagation is dependent on the spatially and temporally varying properties of the water column and sea floor, and is frequency-dependent. As a result of the dependence on a large number of varying factors, ambient sound levels can be expected to vary widely over both coarse and fine spatial and temporal scales. Sound levels at a given frequency and location can vary by 10-20 decibels (dB) from day to day (Richardson

et al.,

1995). The result is that, depending on the source type and its intensity, sound from the specified activity may be a negligible addition to the local environment or could form a distinctive signal that may affect marine mammals. Details of source types are described in the following text.

Sounds are often considered to fall into one of two general types: Pulsed and non-pulsed (defined in the following). The distinction between these two sound types is important because they have differing potential to cause physical effects, particularly with regard to hearing (

e.g.,

Ward, 1997 in Southall

et al.,

2007). Please see Southall

et al.

(2007) and NMFS'

Technical Guidance for Assessing the Effects of Anthropogenic Sound on Marine Mammal Hearing (Version 2.0) Underwater Thresholds for Onset of Permanent and Temporary Threshold Shift

(Acoustic Technical Guidance) (NMFS, 2018) for an in-depth discussion of these concepts. The distinction between these two sound types is not always obvious, as certain signals share properties of both pulsed and non-pulsed sounds. A signal near a source could be categorized as a pulse, but due to propagation effects as it moves farther from the source, the signal duration becomes longer (

e.g.,

Greene and Richardson, 1988).

Pulsed sound sources (

e.g.,

airguns, explosions, gunshots, sonic booms, impact pile driving) produce signals that are brief (typically considered to be less than one second), broadband, atonal transients (ANSI, 1986, 2005; Harris, 1998; NIOSH, 1998; ISO, 2003) and occur either as isolated events or repeated in some succession. Pulsed sounds are all characterized by a relatively rapid rise from ambient pressure to a maximal pressure value followed by a rapid decay period that may include a period of diminishing,

oscillating maximal and minimal pressures, and generally have an increased capacity to induce physical injury as compared with sounds that lack these features.

Non-pulsed sounds can be tonal, narrowband, or broadband, brief or prolonged, and may be either continuous or intermittent (ANSI, 1995; NIOSH, 1998). Some of these non-pulsed sounds can be transient signals of short duration but without the essential properties of pulses (

e.g.,

rapid rise time). Examples of non-pulsed sounds include those produced by vessels, aircraft, machinery operations such as drilling or dredging, vibratory pile driving, and active sonar systems. The duration of such sounds, as received at a distance, can be greatly extended in a highly reverberant environment.

Serious Injury or Mortality From Explosive Detonations

Serious injury or mortality to marine mammals from explosive detonations would consist of primary blast injury, which refers to those injuries that result from the compression of a body exposed to a blast wave and is usually observed as barotrauma of gas-containing structures (

e.g.,

lung and gut) and structural damage to the auditory system (Greaves

et al.,

1943; Office of the Surgeon General, 1991; Richmond

et al.,

1973). The near instantaneous high magnitude pressure change near an explosion can injure an animal where tissue material properties significantly differ from the surrounding environment, such as around air-filled cavities in the lungs or gastrointestinal (GI) tract. The gas-containing organs (lungs and GI tract) are most vulnerable to primary blast injury. Severe injuries to these organs are presumed to result in mortality (

e.g.,

severe lung damage may introduce air into the cardiopulmonary vascular system, resulting in lethal air emboli). Large pressure changes at tissue-air interfaces in the lungs and GI tract may cause tissue rupture, resulting in a range of injuries depending on degree of exposure. Recoverable injuries would include slight lung injury, such as capillary interstitial bleeding, and contusions to the GI tract. More severe injuries, such as tissue lacerations, major hemorrhage, organ rupture, or air in the chest cavity (pneumothorax), would significantly reduce fitness and likely cause death in the wild. Rupture of the lung may also introduce air into the vascular system, producing air emboli that can cause a stroke or heart attack by restricting oxygen delivery to critical organs. Susceptibility would increase with depth, until normal lung collapse (due to increasing hydrostatic pressure) and increasing ambient pressures again reduce susceptibility.

The Navy performed a quantitative analysis (refer to the Navy's Acoustic Effects Model section) to estimate the probability that marine mammals could be exposed to the sound and energy from explosions during Navy testing and training activities and the effects of those exposures. The effects of underwater explosions on marine mammals depend on a variety of factors including animal size and depth; charge size and depth; depth of the water column; and distance between the animal and the charge. In general, an animal would be less susceptible to injury near the water surface because the pressure wave reflected from the water surface would interfere with the direct path pressure wave, reducing positive pressure exposure. There are no explosives detonated underwater for the proposed activities, and those that detonate at or near the surface of the water are unlikely to transfer energy underwater sufficient to result in non-auditory injury (GI injury or lung injury) or mortality. NMFS agrees with the Navy's analysis that no mortality or serious injury from tissue damage in the form of GI injury or lung injury is anticipated to result from the proposed activities. The Navy did not request and NMFS does not propose it for authorization or discuss further. For additional details on the criteria for estimating non-auditory physiological impacts on marine mammals due to naval underwater explosions, we refer the reader to the report,

Criteria and Thresholds for U.S. Navy Acoustic and Explosive Effects Analysis (Phase III)

(U.S. Department of the Navy, 2017e).

Hearing Loss—Threshold Shift

Marine mammals exposed to high-intensity sound, or to lower-intensity sound for prolonged periods, can experience hearing threshold shift, which is the loss of hearing sensitivity at certain frequency ranges after cessation of sound (Finneran, 2015). Threshold shift can be permanent (PTS), in which case the loss of hearing sensitivity is not fully recoverable, or temporary (TTS), in which case the animal's hearing threshold would recover over time (Southall

et al.,

2007). Irreparable damage to the inner or outer cochlear hair cells may cause PTS; however, other mechanisms are also involved, such as exceeding the elastic limits of certain tissues and membranes in the middle and inner ears and resultant changes in the chemical composition of the inner ear fluids (Southall

et al.,

2007). PTS is considered an injury and Level A harassment while TTS is considered to be Level B harassment and

not

considered an injury.

Hearing loss, or threshold shift (TS), is typically quantified in terms of the amount (in decibels [dB]) that hearing thresholds at one or more specified frequencies are elevated, compared to their pre-exposure values, at some specific time after the noise exposure. The amount of TS measured usually decreases with increasing recovery time—the amount of time that has elapsed since a noise exposure. If the TS eventually returns to zero (

i.e.,

the hearing threshold returns to the pre-exposure value), the threshold shift is called a TTS. If the TS does not completely recover (the threshold remains elevated compared to the pre-exposure value), the remaining TS is a PTS.

Hearing loss has only been studied in a few species of marine mammals, although hearing studies with terrestrial mammals are also informative. There are no direct measurements of hearing loss in marine mammals due to exposure to explosive sources. The sound resulting from an explosive detonation is considered an impulsive sound and shares important qualities (

i.e.,

short duration and fast rise time) with other impulsive sounds such as those produced by air guns. General research findings regarding TTS and PTS in marine mammals, as well as findings specific to exposure to other impulsive sound sources, are discussed in Section 6.4.1.2, (Loss of Hearing Sensitivity and Auditory Injury) of the Navy's application.

Marine mammal TTS data from impulsive sources are limited to two studies with measured TTS of 6 dB or more: Finneran

et al.

(2002) reported behaviorally measured TTSs of 6 and 7 dB in a beluga exposed to single impulses from a seismic water gun, and Lucke

et al.

(2009) reported Audio-evoked Potential measured TTS of 7-20 dB in a harbor porpoise exposed to single impulses from a seismic air gun.

In addition to these data, Kastelein

et al.

(2015a) reported behaviorally measured mean TTS of 4 dB at 8 kHz and 2 dB at 4 kHz after a harbor porpoise was exposed to a series of impulsive sounds produced by broadcasting underwater recordings of impact pile driving strikes through underwater sound projectors. The cumulative SEL was approximately 180 decibels referenced to 1 micropascal squared seconds (dB re 1 μPa

2

s). The pressure waveforms for the simulated pile strikes exhibited significant

“ringing” not present in the original recordings, and most of the energy in the broadcasts was between 500 and 800 Hz. As a result, some questions exist regarding whether the fatiguing signals were representative of underwater pressure signatures from impact pile driving.

Several impulsive noise exposure studies have also been conducted without behaviorally measurable TTS. Specifically, Finneran

et al.

(2000) exposed dolphins and belugas to single impulses from an “explosion simulator,” and Finneran

et al.

(2015) exposed three dolphins to sequences of 10 impulses from a seismic air gun (maximum cumulative SEL = 193-195 dB re 1 μPa

2

s, peak SPL = 196-210 dB re 1 μPa) without measurable TTS. Finneran

et al.

(2003) exposed two sea lions to single impulses from an arc-gap transducer with no measurable TTS (maximum unweighted SEL = 163 dB re 1 μPa

2

s, peak SPL = 183 dB re 1 μPa).

Numerous studies have directly examined noise-induced hearing loss in marine mammals from non-impulsive sources (see Finneran, 2015). In these studies, hearing thresholds were measured in marine mammals before and after exposure to intense sounds. The difference between the pre-exposure and post-exposure thresholds was then used to determine the amount of TTS at various post-exposure times. The major findings from these studies, which include the following, highlight general concepts that are thought to be applicable across all types of sounds:

• The amount of TTS varies with the hearing test frequency. As the exposure SPL increases, the frequency at which the maximum TTS occurs also increases (Kastelein et al., 2014b). For high-level exposures, the maximum TTS typically occurs one-half to one octave above the exposure frequency (Finneran

et al.,

2007; Mooney

et al.,

2009a; Nachtigall

et al.,

2004; Popov

et al.,

2011; Popov

et al.,

2013; Schlundt

et al.,

2000). The overall spread of TTS from tonal exposures can therefore extend over a large frequency range (

i.e.,

narrowband exposures can produce broadband [greater than one octave] TTS).

• The amount of TTS increases with exposure SPL and duration and is correlated with sound exposure level (SEL), especially if the range of exposure durations is relatively small (Kastak

et al.,

2007; Kastelein

et al.,

2014b; Popov

et al.,

2014). As the exposure duration increases, however, the relationship between TTS and SEL begins to break down. Specifically, duration has a more significant effect on TTS than would be predicted on the basis of SEL alone (Finneran

et al.,

2010a, 2010b; Kastak

et al.,

2005; Mooney

et al.,

2009a). This means if two exposures have the same SEL but different durations, the exposure with the longer duration (thus lower SPL) will tend to produce more TTS than the exposure with the higher SPL and shorter duration. In most acoustic impact assessments, the scenarios of interest involve shorter duration exposures than the marine mammal experimental data from which impact thresholds are derived; therefore, use of SEL tends to overestimate the amount of TTS. Despite this, SEL continues to be used in many situations because it is relatively simple, more accurate than SPL alone, and lends itself easily to scenarios involving multiple exposures with different SPL.

• The amount of TTS depends on the exposure frequency. Sounds at low frequencies, well below the region of best sensitivity, are less hazardous than those at higher frequencies, near the region of best sensitivity (Finneran and Schlundt, 2013). The onset of TTS—defined as the exposure level necessary to produce 6 dB of TTS (

i.e.,

clearly above the typical variation in threshold measurements)—also varies with exposure frequency. At low frequencies onset-TTS exposure levels are higher compared to those in the region of best sensitivity.

• TTS can accumulate across multiple exposures, but the resulting TTS will be less than the TTS from a single, continuous exposure with the same SEL (Finneran

et al.,

2010a; Kastelein

et al.,

2014a; Kastelein

et al.,

2015b; Mooney

et al.,

2009b). This means that TTS predictions based on the total, cumulative SEL will overestimate the amount of TTS from intermittent exposures such as sonars and impulsive sources.

• The amount of observed TTS tends to decrease with increasing time following the exposure; however, the relationship is not monotonic (

i.e.,

increasing exposure does not always increase TTS). The time required for complete recovery of hearing depends on the magnitude of the initial shift; for relatively small shifts recovery may be complete in a few minutes, while large shifts (

e.g.,

~40 dB) may require several days for recovery. Under many circumstances TTS recovers linearly with the logarithm of time (Finneran e

t al.,

2010a, 2010b; Finneran and Schlundt, 2013; Kastelein

et al.,

2012a; Kastelein

et al.,

2012b; Kastelein

et al.,

2013a; Kastelein

et al.,

2014a, 2014b; Kastelein

et al.,

2014c; Popov

et al.,

2011; Popov

et al.,

2013; Popov

et al.,

2014). This means that for each doubling of recovery time, the amount of TTS will decrease by the same amount (

e.g.,

6 dB recovery per doubling of time).

The proposed activities include both TTS and a limited amount of PTS on some marine mammals.

Hearing Loss from SNI Target and Missile Launches

—Missile launches are characterized by sudden onset of sound, moderate to high peak sound levels (depending on the type of missile and distance), and short sound duration. Although it is possible that some pinnipeds may incur TTS during launches from SNI, hearing impairment has not been measured for pinniped species exposed to launch sounds. Auditory brainstem response

(i.e.,

hearing assessment using measurements of electrical responses of the brain) was used to demonstrate that harbor seals did not exhibit loss in hearing sensitivity following launches of large rockets at Vandenberg Air Force Base (VAFB) (Thorson

et al.,

1999; Thorson

et al.,

1998). However, the hearing tests did not begin until at least 45 minutes after the launch; therefore, harbor seals may have incurred TTS which was undetectable by the time testing was begun. There was no sign of PTS in any of the harbor seals tested (Thorson

et al.,

1999; Thorson

et al.,

1998). Since 2001, no launch events at SNI have exposed pinnipeds to noise levels at or exceeding those where PTS could be incurred.

Based on measurements of received sound levels during previous launches at SNI (Burke 2017; Holst

et al.,

2010; Holst

et al.,

2005a; Holst

et al.,

2008; Holst

et al.,

2011; Ugoretz 2016; Ugoretz and Greene Jr. 2012), the Navy expects that there is a very limited potential of TTS for a few of the pinnipeds present, particularly for phocids. Available evidence from launch monitoring at SNI in 2001-2017 suggests that only a small number of launch events produced sound levels that could elicit TTS for some pinnipeds (Burke 2017; Holst

et al.,

2008; Holst

et al.,

2011; Ugoretz 2016; Ugoretz and Greene Jr. 2012). In general, if any TTS were to occur to pinnipeds, it is expected to be mild and reversible. It is possible that some launch sounds as measured close to the launchers may exceed the permanent threshold shift (PTS) criteria, but it is not expected that any pinnipeds would be close enough to the launchers to be exposed to sounds strong enough to cause PTS. Due to the expected sound levels of the activities proposed and the distance of the activity from marine mammal habitat, the effects of sounds from the proposed activities are unlikely to result in PTS.

Physiological Stress

There is growing interest in monitoring and assessing the impacts of stress responses to sound in marine animals. Classic stress responses begin when an animal's central nervous system perceives a potential threat to its homeostasis. That perception triggers stress responses regardless of whether a stimulus actually threatens the animal; the mere perception of a threat is sufficient to trigger a stress response (Moberg, 2000; Sapolsky

et al.,

2005; Seyle, 1950). Once an animal's central nervous system perceives a threat, it mounts a biological response or defense that consists of a combination of the four general biological defense responses: behavioral responses, autonomic nervous system responses, neuroendocrine responses, or immune responses.

According to Moberg (2000), in the case of many stressors, an animal's first and sometimes most economical (in terms of biotic costs) response is behavioral avoidance of the potential stressor or avoidance of continued exposure to a stressor. An animal's second line of defense to stressors involves the sympathetic part of the autonomic nervous system and the classical “fight or flight” response which includes the cardiovascular system, the gastrointestinal system, the exocrine glands, and the adrenal medulla to produce changes in heart rate, blood pressure, and gastrointestinal activity that humans commonly associate with “stress.” These responses have a relatively short duration and may or may not have significant long-term effect on an animal's welfare.

An animal's third line of defense to stressors involves its neuroendocrine systems or sympathetic nervous systems; the system that has received the most study has been the hypothalmus-pituitary-adrenal system (also known as the HPA axis in mammals or the hypothalamus-pituitary-interrenal axis in fish and some reptiles). Unlike stress responses associated with the autonomic nervous system, virtually all neuro-endocrine functions that are affected by stress—including immune competence, reproduction, metabolism, and behavior—are regulated by pituitary hormones. Stress-induced changes in the secretion of pituitary hormones have been implicated in failed reproduction (Moberg, 1987; Rivier and Rivest, 1991), altered metabolism (Elasser

et al.,

2000), reduced immune competence (Blecha, 2000), and behavioral disturbance (Moberg, 1987; Blecha, 2000). Increases in the circulation of glucocorticosteroids (cortisol, corticosterone, and aldosterone in marine mammals; see Romano

et al.,

2004) have been equated with stress for many years.

Because there are many unknowns regarding the occurrence of acoustically induced stress responses in marine mammals, it is assumed that any physiological response (

e.g.,

hearing loss or injury) or significant behavioral response is also associated with a stress response.

Auditory Masking

Sound can disrupt behavior through masking, or interfering with, an animal's ability to detect, recognize, or discriminate between acoustic signals of interest (

e.g.,

those used for intraspecific communication and social interactions, prey detection, predator avoidance, or navigation) (Richardson

et al.,

1995; Erbe and Farmer, 2000; Tyack, 2000; Erbe

et al.,

2016). Masking occurs when the receipt of a sound is interfered with by another coincident sound at similar frequencies and at similar or higher intensity, and may occur whether the sound is natural (

e.g.,

snapping shrimp, wind, waves, precipitation) or anthropogenic (

e.g.,

shipping, sonar, seismic exploration) in origin. As described in detail in the 2020 PMSR DSEIS/OEIS, the ability of a noise source to mask biologically important sounds depends on the characteristics of both the noise source and the signal of interest (

e.g.,

signal-to-noise ratio, temporal variability, direction), in relation to each other and to an animal's hearing abilities (

e.g.,

sensitivity, frequency range, critical ratios, frequency discrimination, directional discrimination, age, or TTS hearing loss), and existing ambient noise and propagation conditions. Masking these acoustic signals can disturb the behavior of individual animals, groups of animals, or entire populations. Masking can lead to behavioral changes including vocal changes (

e.g.,

Lombard effect, increasing amplitude, or changing frequency), cessation of foraging, and leaving an area, to both signalers and receivers, in an attempt to compensate for noise levels (Erbe

et al.,

2016). Masking only occurs in the presence of the masking noise and does not persist after the cessation of the noise. Masking may lead to a change in vocalizations or a change in behavior (

e.g.,

cessation of foraging, leaving an area). There are no direct observations of masking in marine mammals due to exposure to sound from explosive detonations or launches and nor would they be predicted given the shorter duration of these sounds.

Behavioral Disturbance

Behavioral responses to sound are highly variable and context-specific. Many different variables can influence an animal's perception of and response to (nature and magnitude) an acoustic event. An animal's prior experience with a sound or sound source affects whether it is less likely (habituation) or more likely (sensitization) to respond to certain sounds in the future (animals can also be innately predisposed to respond to certain sounds in certain ways) (Southall

et al.,

2007). Related to the sound itself, the perceived nearness of the sound, bearing of the sound (approaching vs. retreating), the similarity of a sound to biologically relevant sounds in the animal's environment (

i.e.,

calls of predators, prey, or conspecifics), and familiarity of the sound may affect the way an animal responds to the sound (Southall

et al.,

2007, DeRuiter

et al.,

2013). Individuals (of different age, gender, reproductive status,

etc.

) among most populations will have variable hearing capabilities, and differing behavioral sensitivities to sounds that will be affected by prior conditioning, experience, and current activities of those individuals. Often, specific acoustic features of the sound and contextual variables (

i.e.,

proximity, duration, or recurrence of the sound or the current behavior that the marine mammal is engaged in or its prior experience), as well as entirely separate factors such as the physical presence of a nearby vessel, may be more relevant to the animal's response than the received level alone.

Controlled experiments with captive marine mammals have shown pronounced behavioral reactions, including avoidance of loud underwater sound sources (Ridgway

et al.,

1997; Finneran

et al.,

2003). These may be of limited relevance to the proposed activities given that airborne sound, and not underwater sound, may result in harassment of marine mammals as a result of the proposed activities; however we present this information as background on the potential impacts of sound on marine mammals. Observed responses of wild marine mammals to loud pulsed sound sources (typically seismic guns or acoustic harassment devices) have been varied but often consist of avoidance behavior or other behavioral changes suggesting discomfort (Morton and Symonds, 2002; Thorson and Reyff, 2006; see also Gordon

et al.,

2004; Wartzok

et al.,

2003; Nowacek

et al.,

2007).

The onset of noise can result in temporary, short-term changes in an animal's typical behavior and/or

avoidance of the affected area. These behavioral changes may include: reduced/increased vocal activities; changing/cessation of certain behavioral activities (such as socializing or feeding); visible startle response or aggressive behavior; avoidance of areas where sound sources are located; and/or flight responses (Richardson

et al.,

1995).

The biological significance of many of these behavioral disturbances is difficult to predict, especially if the detected disturbances appear minor. However, the consequences of behavioral modification could potentially be biologically significant if the change affects growth, survival, or reproduction. The onset of behavioral disturbance from anthropogenic sound depends on both external factors (characteristics of sound sources and their paths) and the specific characteristics of the receiving animals (hearing, motivation, experience, demography) and is difficult to predict (Southall

et al.,

2007).

Ellison

et al.

(2012) outlined an approach to assessing the effects of sound on marine mammals that incorporates contextual-based factors. The authors recommend considering not just the received level of sound, but also the activity the animal is engaged in at the time the sound is received, the nature and novelty of the sound (

i.e.,

is this a new sound from the animal's perspective), and the distance between the sound source and the animal. They submit that this “exposure context,” as described, greatly influences the type of behavioral response exhibited by the animal. Forney

et al.

(2017) also point out that an apparent lack of response (

e.g.,

no displacement or avoidance of a sound source) may not necessarily mean there is no cost to the individual or population, as some resources or habitats may be of such high value that animals may choose to stay, even when experiencing stress or hearing loss. Forney

et al.

(2017) recommend considering both the costs of remaining in an area of noise exposure such as TTS, PTS, or masking, which could lead to an increased risk of predation or other threats or a decreased capability to forage, and the costs of displacement, including potential increased risk of vessel strike, increased risks of predation or competition for resources, or decreased habitat suitable for foraging, resting, or socializing. This sort of contextual information is challenging to predict with accuracy for ongoing activities that occur over large spatial and temporal expanses. However, distance is one contextual factor for which data exist to quantitatively inform a take estimate, and the method for predicting Level B harassment in this proposed rule does consider distance to the source. Other factors are often considered qualitatively in the analysis of the likely consequences of sound exposure, where supporting information is available.

Exposure of marine mammals to sound sources can result in, but is not limited to, no response or any of the following observable responses: Increased alertness; orientation or attraction to a sound source; vocal modifications; cessation of feeding; cessation of social interaction; alteration of movement or diving behavior; habitat abandonment (temporary or permanent); and, in severe cases, panic, flight, stampede, or stranding, potentially resulting in death (Southall

et al.,

2007). A review of marine mammal responses to anthropogenic sound was first conducted by Richardson (1995). More recent reviews (Nowacek

et al.,

2007; DeRuiter

et al.,

2012 and 2013; Ellison

et al.,

2012; Gomez

et al.,

2016) address studies conducted since 1995 and focused on observations where the received sound level of the exposed marine mammal(s) was known or could be estimated. Gomez

et al.

(2016) conducted a review of the literature considering the contextual information of exposure in addition to received level and found that higher received levels were not always associated with more severe behavioral responses and vice versa. Southall

et al.

(2016) states that results demonstrate that some individuals of different species display clear yet varied responses, some of which have negative implications, while others appear to tolerate high levels, and that responses may not be fully predictable with simple acoustic exposure metrics (

e.g.,

received sound level). Rather, the authors state that differences among species and individuals along with contextual aspects of exposure (

e.g.,

behavioral state) appear to affect response probability.

During an activity with a series of explosions (not concurrent multiple explosions shown in a burst), an animal is expected to exhibit a startle reaction to the sound of the first detonation followed by another behavioral response after multiple detonations. At close ranges and high sound levels, avoidance of the area around the explosions is the assumed behavioral response in most cases. In certain circumstances, exposure to loud sounds can interrupt feeding behaviors and potentially decrease foraging success, interfere with communication or migration, or disrupt important reproductive or young-rearing behaviors, among other effects.

Behavioral Disturbance from SNI Target and Missile Launches

—Pinnipeds may be exposed to airborne sounds that have the potential to result in behavioral harassment, depending on an animal's distance from the sound and the type of missile being launched. Sound could cause hauled out pinnipeds to exhibit changes in their normal behavior, such as temporarily abandoning their habitat.

Responses of pinnipeds on beaches exposed to acoustic disturbance arising from launches are highly variable. Harbor seals can be more reactive when hauled out compared to other species, such as northern elephant seals. Northern elephant seals generally exhibit no reaction at all, except perhaps a heads-up response or some stirring. If northern elephant seals do react, it may occur if California sea lions are in the same area mingled with the northern elephant seals and the sea lions react strongly. Responsiveness also varies with time of year and age class, with juvenile pinnipeds being more likely to react by leaving the haulout site. The probability and type of behavioral response will also depend on the season, the group composition of the pinnipeds, and the type of activity in which they are engaged. For example, in some cases, harbor seals at SNI appear to be more responsive during the pupping/breeding season (Holst

et al.

2005a; Holst

et al.

2008), while in others, mothers and pups seem to react less to launches than lone individuals (Ugoretz and Greene Jr. 2012), and California sea lions seem to be consistently less responsive during the pupping season (Holst

et al.

2010; Holst

et al.

2005a; Holst

et al.

2008; Holst

et al.

2011; Holst

et al.

2005b; Ugoretz and Greene Jr. 2012). Though pup abandonment could theoretically result from these reactions, site-specific monitoring data indicate that pup abandonment is not likely to occur as a result of the specified activity because it has not been previously observed. While the reactions are variable, and can involve abrupt movements by some individuals, biological impacts of these responses appear to be limited. The responses are not expected to result in significant injury or mortality, or long-term negative consequences to individuals or pinniped populations on SNI.

Habituation can occur when an animal's response to a stimulus wanes with repeated exposure, usually in the absence of unpleasant associated events (Wartzok

et al.,

2003). Animals are most likely to habituate to sounds that are

predictable and unvarying. The opposite process is sensitization, when an unpleasant experience leads to subsequent responses, often in the form of avoidance, at a lower level of exposure. Behavioral state may affect the type of response as well. For example, animals that are resting may show greater behavioral change in response to disturbing sound levels than animals that are highly motivated to remain in an area for feeding (Richardson

et al.,

1995; NRC, 2003; Wartzok

et al.,

2003).

It is possible that launch-induced flushing or stampedes could have adverse impacts on individual pinnipeds on the west end of SNI. Bowles and Stewart (1980) reported that harbor seals on San Miguel Island reacted to low-altitude jet overflights with alert postures and often with rapid movement across the haulout sites, especially when aircraft were visible. However, on SNI during missile launches in 2001-2017, there was no evidence of launch noise-related injuries or deaths (Burke 2017; Holst

et al.

2010; Holst

et al.

2005a; Holst

et al.

2008; Holst

et al.

2011; Ugoretz 2016; Ugoretz and Greene Jr. 2012). On several occasions, harbor seals and California sea lion adults moved near and sometimes over older pups (

i.e.,

greater than four months old) as the animals moved in response to the launch noises, but the pups were not injured (Holst

et al.,

2010; Holst

et al.,

2005a; Holst

et al.,

2008; Holst

et al.,

2011; Ugoretz and Greene Jr. 2012).

Vessel Strike

Vessel strikes from commercial, recreational, and military vessels are known to affect large whales and have resulted in serious injury and occasional fatalities to cetaceans (Berman-Kowalewski

et al.,

2010; Calambokidis, 2012; Douglas

et al.,

2008; Laggner 2009; Lammers

et al.,

2003). Records of collisions date back to the early 17th century, and the worldwide number of collisions appears to have increased steadily during recent decades (Laist

et al.,

2001; Ritter 2012).

Numerous studies of interactions between surface vessels and marine mammals have demonstrated that free-ranging marine mammals often, but not always (

e.g.,

McKenna

et al.,

2015), engage in avoidance behavior when surface vessels move toward them. It is not clear whether these responses are caused by the physical presence of a surface vessel, the underwater noise generated by the vessel, or an interaction between the two (Amaral and Carlson, 2005; Au and Green, 2000; Bain

et al.,

2006; Bauer 1986; Bejder

et al.,

1999; Bejder and Lusseau, 2008; Bejder

et al.,

2009; Bryant

et al.,

1984; Corkeron, 1995; Erbe, 2002; Félix, 2001; Goodwin and Cotton, 2004; Lemon

et al.,

2006; Lusseau, 2003; Lusseau, 2006; Magalhaes

et al.,

2002; Nowacek

et al.,

2001; Richter

et al.,

2003; Scheidat

et al.,

2004; Simmonds, 2005; Watkins, 1986; Williams

et al.,

2002; Wursig

et al.,

1998). Several authors suggest that the noise generated during motion is probably an important factor (Blane and Jaakson, 1994; Evans

et al.,

1992; Evans

et al.,

1994). Water disturbance may also be a factor. These studies suggest that the behavioral responses of marine mammals to surface vessels are similar to their behavioral responses to predators. Avoidance behavior is expected to be even stronger in the subset of instances during which the Navy is conducting training or testing activities using explosives.

The marine mammals most vulnerable to vessel strikes are those that spend extended periods of time at the surface in order to restore oxygen levels within their tissues after deep dives (

e.g.,

sperm whales). In addition, some baleen whales seem generally unresponsive to vessel sound, making them more susceptible to vessel collisions (Nowacek

et al.,

2004). These species are primarily large, slow moving whales.

Some researchers have suggested the relative risk of a vessel strike can be assessed as a function of animal density and the magnitude of vessel traffic (

e.g.,

Fonnesbeck

et al.,

2008; Vanderlaan

et al.,

2008). Differences among vessel types also influence the probability of a vessel strike. The ability of any ship to detect a marine mammal and avoid a collision depends on a variety of factors, including environmental conditions, ship design, size, speed, and ability and number of personnel observing, as well as the behavior of the animal. Vessel speed, size, and mass are all important factors in determining if injury or death of a marine mammal is likely due to a vessel strike. For large vessels, speed and angle of approach can influence the severity of a strike. For example, Vanderlaan and Taggart (2007) found that, between vessel speeds of 8.6 and 15 knots, the probability that a vessel strike is lethal increases from 0.21 to 0.79. Large whales also do not have to be at the water's surface to be struck. Silber

et al.

(2010) found when a whale is below the surface (about one to two times the vessel draft), under certain circumstances (vessel speed and location of the whale relative to the ship's centerline), there is likely to be a pronounced propeller suction effect. This suction effect may draw the whale into the hull of the ship, increasing the probability of propeller strikes.

There are some key differences between the operation of military and non-military vessels, which make the likelihood of a military vessel striking a whale lower than some other vessels (

e.g.,

commercial merchant vessels). Key differences include:

• Many military ships have their bridges positioned closer to the bow, offering better visibility ahead of the ship (compared to a commercial merchant vessel);

• There are often aircraft associated with the training or testing activity (which can serve as Lookouts), which can more readily detect cetaceans in the vicinity of a vessel or ahead of a vessel's present course before crew on the vessel would be able to detect them;

• Military ships are generally more maneuverable than commercial merchant vessels, and if cetaceans are spotted in the path of the ship, could be capable of changing course more quickly;

• The crew size on military vessels is generally larger than merchant ships, allowing for stationing more trained Lookouts on the bridge. At all times when Navy vessels are underway, trained Lookouts and bridge navigation teams are used to detect objects on the surface of the water ahead of the ship, including cetaceans. Additional Lookouts, beyond those already stationed on the bridge and on navigation teams, are positioned as Lookouts during some training events; and

• When submerged, submarines are generally slow moving (to avoid detection) and therefore marine mammals at depth with a submarine are likely able to avoid collision with the submarine. When a submarine is transiting on the surface, there are Lookouts serving the same function as they do on surface ships.

While there have been vessel strikes documented with commercial vessels, NMFS has no documented vessel strikes of marine mammals by the Navy in the PMSR Study Area since the Navy started keeping records of ship strike in 1995. The only large Navy vessels homebased in the PMSR local area (Port Hueneme) are the Self Defense Test Ship and the Mobile Ship Target, which are both greater than 200 ft in length. There are smaller vessels used either as targets or for target recovery as well. The majority of Navy vessels (

e.g.,

LCS, destroyers) used during testing and training on the PMSR Study Area transit from San Diego Navy bases and typically transit further offshore and enter/exit the PMSR Study Area from

the southwestern boundaries to avoid commercial vessel traffic in and out of the Ports or Los Angeles/Long Beach via the Santa Barbara Channel.

The Navy transits at safer speeds and has other protective measures in place during transits, such as using Lookouts and maintaining safe distances from marine mammals (

e.g.,

500 yd (457.2 m) for whales and 200 yd (182.88 m) around other marine mammals except bow-riding dolphins and pinnipeds hauled out on man-made navigational structures, port structures, and vessels). A DoD funded study (Mintz, 2016) on commercial and military vessel traffic in Southern California found that median vessel speed for Navy vessels in the Santa Barbara Channel and nearshore areas of the PMSR Study Area and SOCAL (part of the HSTT Study Area) was between 3 to 8 knots. Speed increased as vessels transited further offshore, between 10-16 knots, with the higher value on the furthest offshore areas of the PMSR Study Area. Commercial tankers and cargo median vessel speeds were between 8-14 knots for the same nearshore areas. Mintz (2016) indicated that Navy vessels make up only 4 percent of the overall vessel traffic off Southern California (PMSR/SOCAL). The data collected for Mintz (2016) was collected via AIS for commercial vessel data and SeaLink for military vessels (a classified Navy/Coast Guard database maintained by the Office of Naval Intelligence). The median surface speed of two of the classes of vessels used on the PMSR Study Area from 2011 through 2015 was below 12 knots. This median speed includes those training and testing operations that require elevated speeds, and being slightly above 10 knots, indicates that Naval vessels typically operate at speeds that would be expected to reduce the potential of vessel strike of a marine mammal.

The Navy has several standard operating procedures for vessel safety that could result in a secondary benefit to marine mammals through a reduction in the potential for vessel strike. For example, ships operated by or for the Navy have personnel assigned to stand watch at all times, day and night, when moving through the water (

i.e.,

when the vessel is underway). Watch personnel undertake extensive training in accordance with the U.S. Navy Lookout Training Handbook or civilian equivalent. A primary duty of watch personnel is to ensure safety of the ship, which includes the requirement to detect and report all objects and disturbances sighted in the water that may be indicative of a threat to the ship and its crew, such as debris, a periscope, surfaced submarine, or surface disturbance. Per safety requirements, watch personnel also report any marine mammals sighted that have the potential to be in the direct path of the ship, as a standard collision avoidance procedure. Navy vessels are required to operate in accordance with applicable navigation rules. These rules require that vessels proceed at a safer speed so proper and effective action can be taken to avoid collision and so vessels can be stopped within a distance appropriate to the prevailing circumstances and conditions. In addition to complying with navigation requirements, Navy ships transit at speeds that are optimal for fuel conservation, to maintain ship schedules, and to meet mission requirements. Vessel captains use the totality of the circumstances to ensure the vessel is traveling at appropriate speeds in accordance with navigation. This Navy message is also consistent with a message issued by the U.S. Coast Guard for vessels operating in the 11th district (covering the waters in and around the PMSR) as a Notice to Mariners that also informs operators about the presence of populations of blue, humpback, and fin whales in the area (see U.S. Coast Guard (2019) for further details).

For more information, please see section 3.7.1.1.1

Vessels as a Strike Stressor

in the 2020 PMSR DEIS/OEIS. Additionally, the Navy has fewer vessel transits than commercial entities in the PMSR Study Area. To put the PMSR Navy vessel operations level in perspective, Table 6 includes an estimate of annual commercial shipping activity compared with vessel use in the PMSR Study Area. These annual estimates are representable of any given year as proposed for this rule. Navy vessels account for only about nine percent of the vessel traffic within the PMSR Study Area.

EP16JY21.003

In addition, large Navy vessels (greater than 18 m in length) within the offshore areas of range complexes and testing ranges operate differently from commercial vessels in ways that may reduce potential for whale collisions. Surface ships operated by or for the Navy have multiple personnel assigned to stand watch at all times, when a ship or surfaced submarine is moving through the water (underway). A primary duty of personnel standing watch on surface ships is to detect and report all objects and disturbances sighted in the water that may indicate a threat to the vessel and its crew, such as debris, a periscope, surfaced submarine, or surface disturbance. Per vessel safety requirements, personnel standing watch also report any marine mammals sighted in the path of the vessel as a standard collision avoidance procedure. All vessels proceed at a safer speed so they can take proper and effective action to avoid a collision with any sighted object or disturbance, and can be stopped within a distance appropriate to the prevailing circumstances and conditions.

Between 2007 and 2009, the Navy developed and distributed additional training, mitigation, and reporting tools to Navy operators to improve marine

mammal protection and to ensure compliance with LOA requirements. In 2009, the Navy implemented Marine Species Awareness Training designed to improve effectiveness of visual observation for marine resources, including marine mammals. For over a decade, the Navy has implemented the Protective Measures Assessment Protocol software tool, which provides operators with notification of the required mitigation and a visual display of the planned training or testing activity location overlaid with relevant environmental data.

The Navy does not anticipate vessel strikes and has not requested authorization to take marine mammals by serious injury or mortality within the PMSR Study Area during training and testing activities. NMFS agrees with the Navy's conclusions based on this qualitative analysis; therefore, NMFS has preliminarily determined that the Navy's decision not to request take authorization for vessel strike of large whales is supported by multiple factors, including no previous instances of strikes by Navy vessels in the PMSR Study Area, relatively low at-sea days compared to other Navy training and testing study areas, fewer vessels used compared to other Navy training and testing study areas, ways in which the larger vessels operate in the PMSR Study Area, and the mitigation measures that would be in place to further minimize potential vessel strike.

In addition to the reasons listed above that make it unlikely that the Navy will hit a large whale (more maneuverable ships, larger crew, etc.), the following are additional reasons that vessel strike of dolphins and small whales is very unlikely. Dating back more than 20 years and for as long as it has kept records, the Navy has no records of individuals of these groups being struck by a vessel as a result of Navy activities and, further, their smaller size and maneuverability make a strike unlikely. Also, NMFS has never received any reports from other authorized activities indicating that these species have been struck by vessels. Worldwide ship strike records show little evidence of strikes of these groups from the shipping sector and larger vessels, and the majority of the Navy's activities involving faster-moving vessels (that could be considered more likely to hit a marine mammal) are located in offshore areas where smaller delphinid densities are lower. Based on this information, NMFS concurs with the Navy's assessment that vessel strike is not likely to occur for either large whales or smaller marine mammals.

Marine Mammal Habitat

Impacts on marine mammal habitat are part of the consideration in making a finding of negligible impact on the species and stocks of marine mammals. Habitat includes, but is not necessarily limited to, rookeries, mating grounds, feeding areas, and areas of similar significance. We do not anticipate that the Navy's proposed activities would result in permanent effects on the habitats used by the marine mammals in the PMSR Study Area, including the availability of prey (

i.e.,

fish and invertebrates). While it is anticipated that the proposed activity may result in marine mammals avoiding certain areas due to temporary ensonification, this impact to habitat is temporary and reversible and was considered in further detail earlier in this document, as behavioral modification. The main impact associated with the proposed activity will be temporarily elevated noise levels and the associated direct effects on marine mammals, previously discussed in this notice.

Effects to Prey

—Sound may affect marine mammals through impacts on the abundance, behavior, or distribution of prey species (

e.g.,

crustaceans, cephalopods, fish, zooplankton). Marine mammal prey varies by species, season, and location and, for some species, is not well documented. Here, we describe studies regarding the effects of noise on known marine mammal prey.

Fish utilize the soundscape and components of sound in their environment to perform important functions such as foraging, predator avoidance, mating, and spawning (

e.g.,

Zelick

et al.,

1999; Fay, 2009). The most likely effects on fishes exposed to loud, intermittent, low-frequency sounds are behavioral responses (

i.e.,

flight or avoidance). Short duration, sharp sounds (such as pile driving or air guns) can cause overt or subtle changes in fish behavior and local distribution. The reaction of fish to acoustic sources depends on the physiological state of the fish, past exposures, motivation (

e.g.,

feeding, spawning, migration), and other environmental factors. Key impacts to fishes may include behavioral responses, hearing damage, barotrauma (pressure-related injuries), and mortality.

Fishes, like other vertebrates, have a variety of different sensory systems to glean information from ocean around them (Astrup and Mohl, 1993; Astrup, 1999; Braun and Grande, 2008; Carroll

et al.,

2017; Hawkins and Johnstone, 1978; Ladich and Popper, 2004; Ladich and Schulz-Mirbach, 2016; Mann, 2016; Nedwell

et al.,

2004; Popper

et al.,

2003; Popper

et al.,

2005). Depending on their hearing anatomy and peripheral sensory structures, which vary among species, fishes hear sounds using pressure and particle motion sensitivity capabilities and detect the motion of surrounding water (Fay

et al.,

2008) (terrestrial vertebrates generally only detect pressure). Most marine fishes primarily detect particle motion using the inner ear and lateral line system, while some fishes possess additional morphological adaptations or specializations that can enhance their sensitivity to sound pressure, such as a gas-filled swim bladder (Braun and Grande, 2008; Popper and Fay, 2011).

Hearing capabilities vary considerably between different fish species with data only available for just over 100 species out of the 34,000 marine and freshwater fish species (Eschmeyer and Fong, 2016). In order to better understand acoustic impacts on fishes, fish hearing groups are defined by species that possess a similar continuum of anatomical features which result in varying degrees of hearing sensitivity (Popper and Hastings, 2009a). There are four hearing groups defined for all fish species (modified from Popper

et al.,

2014) within this analysis and they include: Fishes without a swim bladder (

e.g.,

flatfish, sharks, rays,

etc.

); fishes with a swim bladder not involved in hearing (

e.g.,

salmon, cod, pollock,

etc.

); fishes with a swim bladder involved in hearing (

e.g.,

sardines, anchovy, herring,

etc.

); and fishes with a swim bladder involved in hearing and high-frequency hearing (

e.g.,

shad and menhaden). Currently, less data are available to estimate the range of best sensitivity for fishes without a swim bladder.

In terms of behavioral responses of fish, Juanes

et al.

(2017) discuss the potential for negative impacts from anthropogenic soundscapes on fish, but the author's focus was on broader based sounds such as ship and boat noise sources. Occasional behavioral reactions to intermittent explosions occurring at or near the surface are unlikely to cause long-term consequences for individual fish or populations; there are no detonations of explosives occurring underwater from the proposed activities. Fish that experience hearing loss as a result of exposure to explosions may have a reduced ability to detect relevant sounds such as predators, prey, or social vocalizations. However, PTS has not been known to occur in fishes and any hearing loss in fish may be as temporary as the timeframe required to repair or replace the sensory cells that were damaged or destroyed (Popper

et al.,

2005; Popper

et al.,

2014; Smith

et al.,

2006). It is not known if damage to

auditory nerve fibers could occur, and if so, whether fibers would recover during this process. It is also possible for fish to be injured or killed by an explosion in the immediate vicinity of the surface from dropped or fired ordnance. Physical effects from pressure waves generated by detonations at or near the surface could potentially affect fish within proximity of training or testing activities. The shock wave from occurring at or near the surface may be lethal to fish at close range, causing massive organ and tissue damage and internal bleeding (Keevin and Hempen, 1997). At greater distance from the detonation point, the extent of mortality or injury depends on a number of factors including fish size, body shape, orientation, and species (Keevin and Hempen, 1997; Wright, 1982). At the same distance from the source, larger fish are generally less susceptible to death or injury, elongated forms that are round in cross-section are less at risk than deep-bodied forms, and fish oriented sideways to the blast suffer the greatest impact (Edds-Walton and Finneran, 2006; O'Keeffe, 1984; O'Keeffe and Young, 1984; Wiley

et al.,

1981; Yelverton

et al.,

1975). Species with gas-filled organs are more susceptible to injury and mortality than those without them (Gaspin, 1975; Gaspin

et al.,

1976; Goertner

et al.,

1994).

Fish not killed or driven from a location by an explosion might change their behavior, feeding pattern, or distribution. Changes in behavior of fish have been observed as a result of sound produced by explosives, with effect intensified in areas of hard substrate (Wright, 1982). However, Navy would avoid hard substrate to the best extent practical in the course of their activities. Training and testing exercises involving explosions at or near the surface are dispersed in space and time; therefore, repeated exposure of individual fishes are unlikely. Mortality and injury effects to fishes from explosives would be localized around the area of a given explosion, but only if individual fish and the explosive at the surface were co-located at the same time. Fishes deeper in the water column or on the bottom would not be affected by surface explosions. Long-term consequences for fish populations, including key prey species within the PMSR Study Area, would not be expected.

Vessels and in-water devices do not normally collide with adult fish, most of which can detect and avoid them. Exposure of fishes to vessel strike stressors is limited to those fish groups that are large, slow-moving, and may occur near the surface, such as ocean sunfish, whale sharks, basking sharks, and manta rays. These species are distributed widely in offshore portions of the PMSR Study Area. Any isolated cases of a Navy vessel striking an individual could injure that individual, impacting the fitness of an individual fish. Vessel strikes would not pose a risk to most of the other marine fish groups, because many fish can detect and avoid vessel movements, making strikes rare and allowing the fish to return to their normal behavior after the ship or device passes. As a vessel approaches a fish, they could have a detectable behavioral or physiological response (

e.g.,

swimming away and increased heart rate) as the passing vessel displaces them. However, such reactions are not expected to have lasting effects on the survival, growth, recruitment, or reproduction of these marine fish groups at the population level and therefore would not have an impact on marine mammal species as prey items.

In addition to fish, prey sources such as marine invertebrates could potentially be impacted by sound stressors as a result of the proposed activities. However, most marine invertebrates' ability to sense sounds is very limited. In most cases, marine invertebrates would not respond to impulsive sounds. Data on response of invertebrates such as squid, another marine mammal prey species, to anthropogenic sound has been documented (de Soto, 2016; Sole

et al.,

2017b). Explosions could kill or injure nearby marine invertebrates. Vessels also have the potential to impact marine invertebrates by disturbing the water column or sediments, or directly striking organisms (Bishop, 2008). The propeller wash (water displaced by propellers used for propulsion) from vessel movement and water displaced from vessel hulls can potentially disturb marine invertebrates in the water column and is a likely cause of zooplankton mortality (Bickel

et al.,

2011). The localized and short-term exposure to at or near the surface explosions or vessels could displace, injure, or kill zooplankton, invertebrate eggs or larvae, and macro-invertebrates. However, mortality or long-term consequences for a few animals is unlikely to have measurable effects on overall populations. Long-term consequences to marine invertebrate populations would not be expected as a result of exposure to sounds of vessels in the PMSR Study Area.

Military expended materials resulting from training and testing activities could potentially result in minor long-term changes to benthic habitat, however the impacts of small amounts of expended materials are unlikely to have measurable effects on overall populations. Military expended materials may be colonized over time by benthic organisms that prefer hard substrate and would provide structure that could attract some species of fish or invertebrates.

Overall, the combined impacts of sound exposure, explosions, vessel strikes, and military expended materials resulting from the proposed activities would not be expected to have measurable effects on populations of marine mammal prey species. Prey species exposed to sound might move away from the sound source or show no obvious direct effects at all, but a rapid return to normal recruitment, distribution, and behavior is anticipated. Long-term consequences to fish or marine invertebrate populations would not be expected as a result of exposure to sounds or vessels in the PMSR Study Area.

Acoustic Habitat

—Acoustic habitat is the soundscape which encompasses all of the sound present in a particular location and time, as a whole when considered from the perspective of the animals experiencing it. Animals produce sound for, or listen for sounds produced by, conspecifics (communication during feeding, mating, and other social activities), other animals (finding prey or avoiding predators), and the physical environment (finding suitable habitats, navigating). Together, sounds made by animals and the geophysical environment (

e.g.,

produced by earthquakes, lightning, wind, rain, waves) make up the natural contributions to the total acoustics of a place. These acoustic conditions, termed acoustic habitat, are one attribute of an animal's total habitat.

Soundscapes are also defined by, and acoustic habitat influenced by, the total contribution of anthropogenic sound. This may include incidental emissions from sources such as vessel traffic or may be intentionally introduced to the marine environment for data acquisition purposes (

e.g.,

as in the use of air gun arrays) or for Navy training and testing purposes (as in the use of explosives, and target and missile launches on SNI). Anthropogenic noise varies widely in its frequency, content, duration, and loudness, and these characteristics greatly influence the potential habitat-mediated effects to marine mammals, which may range from local effects for brief periods of time to chronic effects over large areas and for long durations. Depending on the extent of effects to habitat, animals may alter their communications signals (thereby

potentially expending additional energy) or miss acoustic cues (either conspecific or adventitious). Problems arising from a failure to detect cues are more likely to occur when noise stimuli are chronic

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