Taking and Importing Marine Mammals; Taking Marine Mammals Incidental to the U.S. Navy Training and Testing Activities in the Hawaii-Southern California Training and Testing Study Area

DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

50 CFR Part 218

[Docket No. 170918908-8501-01]

RIN 0648-BH29

Taking and Importing Marine Mammals; Taking Marine Mammals Incidental to the U.S. Navy Training and Testing Activities in the Hawaii-Southern California Training and Testing 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) for authorization to take marine mammals incidental to the training and testing activities conducted in the Hawaii-Southern California Training and Testing (HSTT) Study Area. Pursuant to the Marine Mammal Protection Act (MMPA), NMFS is requesting comments on its proposal to issue regulations and subsequent Letters 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 MMPA authorizations. Agency responses to public comments will be summarized 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 9, 2018.

ADDRESSES:

You may submit comments, identified by NOAA-NMFS-2018-0071, by any of the following methods:

•

Electronic submissions:

Submit all electronic public comments via the Federal eRulemaking Portal, Go to

www.regulations.gov/#!docketDetail;D=NOAA-NMFS-2018-0071

, click the “Comment Now!” icon, complete the required fields, and enter or attach your comments.

•

Mail:

Submit comments to Jolie Harrison, Chief, Permits and Conservation Division, Office of Protected Resources, National Marine Fisheries Service, 1315 East-West Highway, Silver Spring, MD 20910-3225.

•

Fax:

(301) 713-0376; Attn: Jolie Harrison.

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, etc.), confidential business information, or otherwise sensitive information submitted voluntarily by the sender may be publicly accessible. Do not submit Confidential Business Information or otherwise sensitive or protected information. 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; phone: (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:

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

. In case of problems accessing these documents, please call the contact listed above.

SUPPLEMENTARY INFORMATION:

Background

Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361

et seq.

) direct the Secretary of Commerce (as delegated to NMFS) to allow, upon request, the incidental, but not intentional, taking of small numbers of marine mammals by U.S. citizens who engage in a specified activity (other than commercial fishing) within a specified geographical region if certain findings are made and either regulations are issued or, if the taking is limited to harassment, 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 stock(s), will not have an unmitigable adverse impact on the availability of the species or stock(s) for subsistence uses (where relevant), and if the permissible methods of taking and requirements pertaining to the mitigation, monitoring and reporting of such takings are set forth.

NMFS has defined “negligible impact” in 50 CFR 216.103 as an impact resulting from the specified activity that cannot be reasonably expected to, and is not reasonably likely to, adversely affect the species or stock through effects on annual rates of recruitment or survival.

NMFS has defined “unmitigable adverse impact” in 50 CFR 216.103 as an impact resulting from the specified activity:

(1) That is likely to reduce the availability of the species to a level insufficient for a harvest to meet subsistence needs by: (i) Causing the marine mammals to abandon or avoid hunting areas; (ii) directly displacing subsistence users; or (iii) placing physical barriers between the marine mammals and the subsistence hunters; and

(2) That cannot be sufficiently mitigated by other measures to increase the availability of marine mammals to allow subsistence needs to be met.

The MMPA states that the term “take” means to harass, hunt, capture, kill or attempt to harass, hunt, capture, or kill any marine mammal.

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

Summary of Request

On September 13, 2017, NMFS received an application from the Navy requesting incidental take regulations and two LOAs to take individuals of 39 marine mammal species by Level A and B harassment incidental to training and testing activities (categorized as military readiness activities) from the use of sonar and other transducers, in-water detonations, air guns, and impact pile driving/vibratory extraction in the HSTT Study Area over five years. In addition, the Navy is requesting incidental take authorization by serious injury or mortality of ten takes of two species due to explosives and for up to three takes of large whales from vessel

strikes over the five-year period. The Navy's training and testing activities would occur over five years beginning in December 2018. On October 13, 2017, the Navy sent an amendment to its application and Navy's rulemaking/LOA application was considered final and complete.

The Navy requests two five-year LOAs, one for training and one for testing activities to be conducted within the HSTT Study Area (which extends from the north-central Pacific Ocean, from the mean high tide line in Southern California west to Hawaii and the International Date Line), including the Hawaii and Southern California (SOCAL) Range Complexes, as well as the Silver Strand Training Complex and overlapping a small portion of the Point Mugu Sea Range. The Hawaii Range Complex encompasses ocean areas around the Hawaiian Islands, extending from 16 degrees north latitude to 43 degrees north latitude and from 150 degrees west longitude to the International Date Line. The SOCAL Range Complex is located approximately between Dana Point and San Diego, California, and extends southwest into the Pacific Ocean and also includes a small portion of the Point Mugu Sea Range. The Silver Strand Training Complex is an integrated set of training areas located on and adjacent to the Silver Strand, a narrow, sandy isthmus separating the San Diego Bay from the Pacific Ocean. Please refer to Figure 1-1 of the Navy's rulemaking/LOA application for a map of the HSTT Study Area, Figures 2-1 to 2-4 for the Hawaii Operating Area (where the majority of training and testing activities occur within the Hawaii Range Complex), Figures 2-5 to 2-7 for the SOCAL Range Complex, and Figure 2-8 for the Silver Strand Training Complex. The following types of training and testing, which are classified as military readiness activities pursuant to the MMPA, as amended by the 2004 NDAA, would be covered under the LOAs (if authorized): Amphibious warfare (in-water detonations), anti-submarine warfare (sonar and other transducers, in-water detonations), surface warfare (in-water detonations), mine warfare (sonar and other transducers, in-water detonations), and other warfare activities (sonar and other transducers, pile driving, air guns).

This will be NMFS's third rulemaking (Hawaii and Southern California were separate rules in Phase I) for HSTT activities under the MMPA. NMFS published the first two rules for Phase I effective from January 5, 2009, through January 5, 2014, (74 FR 1456; on January 12, 2009) and effective January 14, 2009, through January 14, 2014 (74 FR 3882 on January 21, 2009) for Hawaii and Southern California, respectively. The rulemaking for Phase II (combined both Hawaii and Southern California) is applicable from December 24, 2013, through December 24, 2018 (78 FR 78106; on December 24, 2013). For this third rulemaking, the Navy is proposing to conduct similar activities as they have conducted over the past nine years under the previous rulemakings.

Background of Request

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. 5062), which ensures 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 activities.

The Navy proposes to conduct training and testing activities within the HSTT Study Area. The Navy has been conducting similar military readiness activities in the Study Area since the 1940s. The tempo and types of training and testing activities have fluctuated because of the introduction of new technologies, the evolving nature of international events, advances in warfighting doctrine and procedures, and changes in force structure (organization of ships, weapons, and personnel). Such developments influence the frequency, duration, intensity, and location of required training and testing activities, but the basic nature of sonar and explosive events conducted in the HSTT Study Area has remained the same.

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 proposed rule account for fluctuations in training and testing in order to meet evolving or emergent military readiness requirements.

Description of the Specified Activity

The Navy is requesting authorization to take marine mammals incidental to conducting training and testing activities. The Navy has determined that acoustic and explosives stressors are most likely to result in impacts on marine mammals that could rise to the level of harassment. Detailed descriptions of these activities are provided in the HSTT Draft Environmental Impact Statement (DEIS)/Overseas EIS (OEIS) (DEIS/OEIS) and in the Navy's rule making/LOA application (

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

) and are summarized here.

Overview of Training and Testing Activities

The Navy routinely trains and tests in the HSTT Study Area in preparation for national defense missions. Training and testing activities covered in the Navy's rulemaking/LOA application are briefly described below, and in more detail within Chapter 2 of the HSTT DEIS/OEIS.

Primary Mission Areas

The Navy categorizes its activities into functional warfare areas called primary mission areas. These activities generally fall into the following seven primary mission areas: Air warfare; amphibious warfare; anti-submarine warfare (ASW); electronic warfare; expeditionary warfare; mine warfare (MIW); and surface warfare (SUW). Most activities addressed in the HSTT DEIS/OEIS are categorized under one of the primary mission areas; the testing community has three additional categories of activities for vessel evaluation, unmanned systems, and acoustic and oceanographic science and technology. Activities that do not fall within one of these areas are listed as “other activities.” Each warfare community (surface, subsurface, aviation, and special warfare) may train in some or all of these primary mission areas. The testing community also categorizes most, but not all, of its testing activities under these primary mission areas.

The Navy describes and analyzes the impacts of its training and testing activities within the HSTT DEIS/OEIS and the Navy's rulemaking/LOA application. In its assessment, the Navy concluded that sonar and other transducers, in-water detonations, air guns, and pile driving/removal were the stressors that would result in impacts on marine mammals that could rise to the level of harassment (and serious injury or mortality by explosives or by vessel strike) as defined under the MMPA. The Navy's rulemaking/LOA application provides the Navy's assessment of potential effects from these stressors in

terms of the various warfare mission areas in which they would be conducted. In terms of Navy's primary warfare areas, this includes:

• Amphibious warfare (in-water detonations);

• ASW (sonar and other transducers, in-water detonations);

• SUW (in-water detonations);

• MIW (sonar and other transducers, in-water detonations); and

• Other warfare activities (sonar and other transducers, impact pile driving/vibratory removal, air guns).

The Navy's training and testing activities in air warfare, electronic warfare, and expeditionary warfare do not involve sonar or other transducers, in-water detonations, pile driving/removal, air guns or any other stressors that could result in harassment, serious injury, or mortality of marine mammals. Therefore, activities in the air, electronic or expeditionary warfare areas are not discussed further in this proposed rule, but are analyzed fully in the Navy's HSTT DEIS/OEIS.

Amphibious Warfare

The mission of amphibious warfare is to project military power from the sea to the shore (

i.e.,

attack a threat on land by a military force embarked on ships) through the use of naval firepower and expeditionary landing forces. Amphibious warfare operations range from small unit reconnaissance or raid missions to large scale amphibious exercises involving multiple ships and aircraft combined into a strike group.

Amphibious warfare training ranges from individual, crew, and small unit events to large task force exercises. Individual and crew training include amphibious vehicles and naval gunfire support training. Such training includes shore assaults, boat raids, airfield or port seizures, and reconnaissance. Large scale amphibious exercises involve ship-to-shore maneuver, naval fire support, such as shore bombardment, and air strike and attacks on targets that are in close proximity to friendly forces.

Testing of guns, munitions, aircraft, ships, and amphibious vessels and vehicles used in amphibious warfare is often integrated into training activities and, in most cases, the systems are used in the same manner in which they are used for fleet training activities. Amphibious warfare tests, when integrated with training activities or conducted separately as full operational evaluations on existing amphibious vessels and vehicles following maintenance, repair, or modernization, may be conducted independently or in conjunction with other amphibious ship and aircraft activities. Testing is performed to ensure effective ship-to-shore coordination and transport of personnel, equipment, and supplies. Tests may also be conducted periodically on other systems, vessels, and aircraft intended for amphibious operations to assess operability and to investigate efficacy of new technologies.

Anti-Submarine Warfare

The mission of ASW is to locate, neutralize, and defeat hostile submarine forces that threaten Navy forces. ASW is based on the principle that surveillance and attack aircraft, ships, and submarines all search for hostile submarines. These forces operate together or independently to gain early warning and detection, and to localize, track, target, and attack submarine threats. ASW training addresses basic skills such as detecting and classifying submarines, as well as evaluating sounds to distinguish between enemy submarines and friendly submarines, ships, and marine life. More advanced training integrates the full spectrum of ASW from detecting and tracking a submarine to attacking a target using either exercise torpedoes (

i.e.,

torpedoes that do not contain a warhead) or simulated weapons. These integrated ASW training exercises are conducted in coordinated, at-sea training events involving submarines, ships, and aircraft. Testing of ASW systems is conducted to develop new technologies and assess weapon performance and operability with new systems and platforms, such as unmanned systems. Testing uses ships, submarines, and aircraft to demonstrate capabilities of torpedoes, missiles, countermeasure systems, and underwater surveillance and communications systems. Tests may be conducted as part of a large-scale fleet training event involving submarines, ships, fixed-wing aircraft, and helicopters. These integrated training events offer opportunities to conduct research and acquisition activities and to train crews in the use of new or newly enhanced systems during a large-scale, complex exercise.

Mine Warfare

The mission of MIW is to detect, classify, and avoid or neutralize (disable) mines to protect Navy ships and submarines and to maintain free access to ports and shipping lanes. MIW also includes offensive mine laying to gain control of or deny the enemy access to sea space. Naval mines can be laid by ships, submarines, or aircraft. MIW neutralization training includes exercises in which ships, aircraft, submarines, underwater vehicles, unmanned vehicles, or marine mammal detection systems search for mine shapes. Personnel train to destroy or disable mines by attaching underwater explosives to or near the mine or using remotely operated vehicles to destroy the mine. Towed influence mine sweep systems mimic a particular ship's magnetic and acoustic signature, which would trigger a real mine causing it to explode.

Testing and development of MIW systems is conducted to improve sonar, laser, and magnetic detectors intended to hunt, locate, and record the positions of mines for avoidance or subsequent neutralization. MIW testing and development falls into two primary categories: Mine detection or classification, and mine countermeasure and neutralization. Mine detection or classification testing involves the use of air, surface, and subsurface vessels and uses sonar, including towed and sidescan sonar, and unmanned vehicles to locate and identify objects underwater. Mine detection and classification systems are sometimes used in conjunction with a mine neutralization system. Mine countermeasure and neutralization testing includes the use of air, surface, and subsurface units to evaluate the effectiveness of detection systems, countermeasure and neutralization systems. Most neutralization tests use mine shapes, or non-explosive practice mines, to evaluate a new or enhanced capability. For example, during a mine neutralization test, a previously located mine is destroyed or rendered nonfunctional using a helicopter or manned/unmanned surface vehicle based system that may involve the deployment of a towed neutralization system.

A small percentage of MIW tests require the use of high-explosive mines to evaluate and confirm the ability of the system or the crews conducting the training or testing to neutralize a high-explosive mine under operational conditions. The majority of MIW systems are deployed by ships, helicopters, and unmanned vehicles. Tests may also be conducted in support of scientific research to support these new technologies.

Surface Warfare (SUW)

The mission of SUW is to obtain control of sea space from which naval forces may operate, and conduct offensive action against other surface, subsurface, and air targets while also defending against enemy forces. In conducting SUW, aircraft use guns, air-launched cruise missiles, or other precision-guided munitions; ships employ torpedoes, naval guns, and

surface-to-surface missiles; and submarines attack surface ships using torpedoes or submarine-launched, anti-ship cruise missiles. SUW includes surface-to-surface gunnery and missile exercises; air-to-surface gunnery, bombing, and missile exercises; submarine missile or torpedo launch events, and the use of other munitions against surface targets.

Testing of weapons used in SUW is conducted to develop new technologies and to assess weapon performance and operability with new systems and platforms, such as unmanned systems. Tests include various air-to-surface guns and missiles, surface-to-surface guns and missiles, and bombing tests. Testing events 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.

Other Warfare Activities

Naval forces conduct additional training, testing and maintenance activities, which fall under other primary mission areas that are not listed above. The HSTT DEIS/OEIS combines these training and testing activities together in an “other activities” grouping for simplicity. These training and testing activities include, but are not limited to, sonar maintenance for ships and submarines, submarine navigation and under-ice certification, elevated causeway system (pile driving and removal), and acoustic and oceanographic research. These activities include the use of various sonar systems, impact pile driving/vibratory extraction, and air guns.

Overview of Major Training Exercises and Other Exercises Within the HSTT Study Area

A major training exercise (MTE) is comprised of several “unit level” range exercises conducted by several units operating together while commanded and controlled by a single commander. These exercises typically employ an exercise scenario developed to train and evaluate the strike group in naval tactical tasks. In an MTE, most of the activities being directed and coordinated by the strike group commander are identical in nature to the activities conducted during individual, crew, and smaller unit level training events. In an MTE, however, these disparate training tasks are conducted in concert, rather than in isolation. Some integrated or coordinated ASW exercises are similar in that they are comprised of several unit level exercises but are generally on a smaller scale than an MTE, are shorter in duration, use fewer assets, and use fewer hours of hull-mounted sonar per exercise. For the purpose of analysis, three key factors are used to identify and group major, integrated, and coordinated exercises including the scale of the exercise, duration of the exercise, and amount of hull-mounted sonar hours modeled/used for the exercise. NMFS considered the effects of all training exercises, not just these major, integrated, and coordinated training exercises in this proposed rule.

Overview of Testing Activities Within the HSTT Study Area

The Navy's research and acquisition community engages in a broad spectrum of testing activities in support of the fleet. These activities include, but are not limited to, basic and applied scientific research and technology development; testing, evaluation, and maintenance of systems (

e.g.,

missiles, radar, and sonar) and platforms (

e.g.,

surface ships, submarines, and aircraft); and acquisition of systems and platforms to support Navy missions and give a technological edge over adversaries. The individual commands within the research and acquisition community included in the Navy's rulemaking/LOA application are the Naval Air Systems Command, the Naval Sea Systems Command, the Office of Naval Research, and the Space and Naval Warfare Systems Command.

Testing activities occur in response to emerging science or fleet operational needs. For example, future Navy experiments to develop a better understanding of ocean currents may be designed based on advancements made by non-government researchers not yet published in the scientific literature. Similarly, future but yet unknown Navy operations within a specific geographic area may require development of modified Navy assets to address local conditions. However, any evolving testing activities that would be covered under this rule would be expected to fall within the range of platforms, activities, sound sources, and other equipment described in this rule and to have impacts that fall within the range (

i.e.,

nature and extent) of those covered within the rule. For example, the Navy identifies “bins” of sound sources to facilitate analyses—

i.e.,

they identify frequency and source level bounds to a bin and then analyze the worst case scenario for that bin to understand the impacts of all of the sources that fall within a bin. While the Navy might be aware that sound source

e.g.,

XYZ1 will definitely be used this year, sound source

e.g.,

XYZ2 might evolve for testing three years from now, but if it falls within the bounds of the same sound source bin, it has been analyzed and any resulting take authorized.

Some testing activities are similar to training activities conducted by the fleet. For example, both the fleet and the research and acquisition community fire torpedoes. While the firing of a torpedo might look identical to an observer, the difference is in the purpose of the firing. The fleet might fire the torpedo to practice the procedures for such a firing, whereas the research and acquisition community might be assessing a new torpedo guidance technology or testing it to ensure the torpedo meets performance specifications and operational requirements.

Naval Air Systems Command Testing Activities

Naval Air Systems Command testing activities generally fall in the primary mission areas used by the fleets. Naval Air Systems Command activities include, but are not limited to, the testing of new aircraft platforms (

e.g.,

the F-35 Joint Strike Fighter aircraft), weapons, and systems (

e.g.,

newly developed sonobuoys) that will ultimately be integrated into fleet training activities. In addition to the testing of new platforms, weapons, and systems, Naval Air Systems Command also conducts lot acceptance testing of weapons and systems, such as sonobuoys.

Naval Sea Systems Command Testing Activities

Naval Sea Systems Command activities are generally aligned with the primary mission areas used by the fleets. Additional activities include, but are not limited to, vessel evaluation, unmanned systems, and other testing activities. In the Navy's rulemaking/LOA application, for testing activities occurring at Navy shipyards and piers, only system testing is included.

Testing activities are conducted throughout the life of a Navy ship, from construction through deactivation from the fleet, to verification of performance and mission capabilities. Activities include pierside and at-sea testing of ship systems, including sonar, acoustic countermeasures, radars, torpedoes, weapons, unmanned systems, and radio equipment; tests to determine how the ship performs at sea (sea trials); development and operational test and evaluation programs for new technologies and systems; and testing on all ships and systems that have undergone overhaul or maintenance.

Office of Naval Research Testing Activities

As the Department of the Navy's science and technology provider, the Office of Naval Research provides technology solutions for Navy and Marine Corps needs. The Office of Naval Research's mission is to plan, foster, and encourage scientific research in recognition of its paramount importance as related to the maintenance of future naval power, and the preservation of national security. The Office of Naval Research manages the Navy's basic, applied, and advanced research to foster transition from science and technology to higher levels of research, development, test, and evaluation. The Office of Naval Research is also a parent organization for the Naval Research Laboratory, which operates as the Navy's corporate research laboratory and conducts a broad multidisciplinary program of scientific research and advanced technological development. Testing conducted by the Office of Naval Research in the HSTT Study Area includes acoustic and oceanographic research, large displacement unmanned underwater vehicle (an innovative naval prototype) research, and emerging mine countermeasure technology research.

Space and Naval Warfare Systems Command Testing Activities

Space and Naval Warfare Systems Command is the information warfare systems command for the U.S. Navy. The mission of the Space and Naval Warfare Systems Command is to acquire, develop, deliver, and sustain decision superiority for the warfighter. Space and Naval Warfare Systems Command Systems Center Pacific is the research and development part of Space and Naval Warfare Systems Command focused on developing and transitioning technologies in the area of command, control, communications, computers, intelligence, surveillance, and reconnaissance. Space and Naval Warfare Systems Command Systems Center Pacific conducts research, development, test, and evaluation projects to support emerging technologies for intelligence, surveillance, and reconnaissance; anti-terrorism and force protection; mine countermeasures; anti‐submarine warfare; oceanographic research; remote sensing; and communications. These activities include, but are not limited to, the testing of surface and subsurface vehicles; intelligence, surveillance, and reconnaissance/information operations sensor systems; underwater surveillance technologies; and underwater communications.

The proposed training and testing activities were evaluated to identify specific components that could act as stressors (

e.g.,

acoustic and explosive) by having direct or indirect impacts on the environment. This analysis included identification of the spatial variation of the identified stressors.

Description of Acoustic and Explosive Stressors

The Navy uses a variety of sensors, 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 Navy's rulemaking/LOA application describes specific components that could act as stressors by having direct or indirect impacts on the environment. This analysis includes identification of the spatial variation of the identified stressors. The following subsections describe the acoustic and explosive stressors for biological resources within the Study Area. Stressor/resource interactions that were determined to have de minimus or no impacts (

i.e.,

vessel, aircraft, weapons noise, and explosions in air) were not carried forward for analysis in the Navy's rulemaking/LOA application. NMFS has reviewed the Navy's analysis and conclusions and finds them complete and supportable.

Acoustic Stressors

Acoustic stressors include acoustic signals emitted into the water for a specific purpose, such as sonar, other transducers (devices that convert energy from one form to another—in this case, to sound waves), and air guns, as well as incidental sources of broadband sound produced as a byproduct of impact pile driving and vibratory extraction. Explosives also produce broadband sound but are characterized separately from other acoustic sources due to their unique hazardous characteristics. Characteristics of each of these sound sources are described in the following sections.

In order to better organize and facilitate the analysis of approximately 300 sources of underwater sound used for training and testing by the Navy, including sonars, other transducers, air guns, and explosives, a series of source classifications, or source bins, was developed. The source classification bins do not include the broadband sounds produced incidental to pile driving, 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 (highest source level, longest duty cycle, or 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 (hours/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.

Sonar and Other Transducers

Active sonar and other transducers emit non-impulsive sound waves into the water to detect objects, safely navigate, and communicate. Passive sonars differ from active sound sources in that they do not emit acoustic signals; rather, they only receive acoustic information about the environment, or listen. In the Navy's rulemaking/LOA application, the terms sonar and other transducers are used to indicate active sound sources unless otherwise specified.

The Navy employs a variety of sonars and other transducers to obtain and transmit information about the undersea environment. Some examples are mid-frequency hull-mounted sonars used to find and track enemy submarines; high-frequency small object detection sonars used to detect mines; high frequency underwater modems used to transfer data over short ranges; and extremely high-frequency (>200 kilohertz (kHz)) Doppler sonars used for navigation, like those used on commercial and private vessels. The characteristics of these sonars and other transducers, such as source level, beam width, directivity, and frequency, depend on the purpose of the source. Higher frequencies can carry more information or provide more information about objects off which they reflect, but attenuate more rapidly. Lower frequencies attenuate less rapidly, so may detect objects over a longer distance, but with less detail.

Propagation of sound produced underwater is highly dependent on

environmental characteristics such as bathymetry, bottom type, water depth, temperature, and salinity. The sound received at a particular location will be different than near the source due to the interaction of many factors, including propagation loss; how the sound is 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 sounds 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 HSTT Study Area.

The sound sources and platforms typically used in naval activities analyzed in the Navy's rulemaking/LOA application are described in Appendix A (Navy Activity Descriptions) of the HSTT DEIS/OEIS. The effects of these factors are explained in Appendix D (Acoustic and Explosive Concepts) of the HSTT DEIS/OEIS. Sonars and other transducers used to obtain and transmit information underwater during Navy training and testing activities generally fall into several categories of use described below.

Anti-Submarine Warfare

Sonar used during ASW would impart the greatest amount of acoustic energy of any category of sonar and other transducers analyzed in the Navy's rulemaking/LOA application. Types of sonars used to detect enemy vessels include hull-mounted, towed, line array, sonobuoy, helicopter dipping, and torpedo sonars. In addition, acoustic targets and decoys (countermeasures) may be deployed to emulate the sound signatures of vessels or repeat received signals.

Most ASW sonars are mid frequency (1-10 kHz) because mid-frequency sound balances sufficient resolution to identify targets with distance over which threats can be identified. However, some sources may use higher or lower frequencies. Duty cycles (the percentage of time acoustic energy is transmitted) can vary widely, from intermittently active to continuously active. For the duty cycle for the AN/SQS-53C, nominally they produce a 1-2 sec ping every 50-60 sec. Continuous active sonars often have substantially lower source levels but transmit the sonar signal much more frequently (greater than 80 percent of the time) when they are on. The beam width of ASW sonars can be wide-ranging in a search mode or highly directional in a track mode.

Most ASW activities involving submarines or submarine targets would occur in waters greater than 600 feet (ft) deep due to safety concerns about running aground at shallower depths. Sonars used for ASW activities would typically be used in waters greater than 200 meters (m) which can vary from beyond three nautical miles (nmi) to 12 nmi or more from shore depending on local bathymetry. Exceptions include use of dipping sonar by helicopters, maintenance of vessel systems while in port, and system checks while vessels transit to or from port.

Mine Warfare, Small Object Detection, and Imaging

Sonars used to locate mines and other small objects, as well those used in imaging (

e.g.,

for hull inspections or imaging of the seafloor), are typically high frequency or very high frequency. Higher frequencies allow for greater resolution but, due to their greater attenuation, are most effective over shorter distances. Mine detection sonar can be deployed (towed or vessel hull-mounted) at variable depths on moving platforms (ships, helicopters, or unmanned vehicles) to sweep a suspected mined area. Most hull-mounted anti-submarine sonars can also be used in an object detection mode known as “Kingfisher” mode. Sonars used for imaging are usually used in close proximity to the area of interest, such as pointing downward near the seafloor.

Mine detection sonar use would be concentrated in areas where practice mines are deployed, typically in water depths less than 200 ft and at established minefields or temporary minefields close to strategic ports and harbors. Kingfisher mode on vessels is most likely to be used when transiting to and from port. Sound sources used for imaging could be used throughout the HSTT Study Area.

Navigation and Safety

Similar to commercial and private vessels, Navy vessels employ navigational acoustic devices including speed logs, Doppler sonars for ship positioning, and fathometers. These may be in use at any time for safe vessel operation. These sources are typically highly directional to obtain specific navigational data.

Communication

Sound sources used to transmit data (such as underwater modems), provide location (pingers), or send a single brief release signal to bottom-mounted devices (acoustic release) may be used throughout the HSTT Study Area. These sources typically have low duty cycles and are usually only used when it is desirable to send a detectable acoustic message.

Classification of Sonar and Other Transducers

Sonars and other transducers are grouped into classes that share an attribute, such as frequency range or purpose of use. Classes are further sorted by bins based on the frequency or bandwidth; source level; and, when warranted, the application in which the source would be used, as follows:

• Frequency of the non-impulsive acoustic source;

○ Low-frequency sources operate below 1 kHz;

○ Mid-frequency sources operate at and above 1 kHz, up to and including 10 kHz;

○ High-frequency sources operate above 10 kHz, up to and including 100 kHz;

○ Very high-frequency sources operate above 100 kHz but below 200 kHz;

• Sound pressure level of the non-impulsive source;

○ Greater than 160 decibels (dB) re 1 micro Pascal (μPa), but less than 180 dB re 1 μPa;

○ Equal to 180 dB re 1 μPa and up to 200 dB re 1 μPa;

○ Greater than 200 dB re 1 μPa;

• Application in which the source would be used;

○ Sources with similar functions that have similar characteristics, such as pulse length (duration of each pulse), beam pattern, and duty cycle.

The bins used for classifying active sonars and transducers that are quantitatively analyzed in the HSTT Study Area are shown in Table 1 below. While general parameters or source characteristics are shown in the table, actual source parameters are classified.

Table 1—Sonar and Transducers Quantitatively Analyzed

Source class category

Bin

Description

Low-Frequency (LF): Sources that produce signals less than 1 kHz

LF3

LF4

LF sources greater than 200 dB.

LF sources equal to 180 dB and up to 200 dB.

LF5

LF sources less than 180 dB.

LF6

LF sources greater than 200 dB with long pulse lengths.

Mid-Frequency (MF): Tactical and non-tactical sources that produce signals between 1-10 kHz

MF1

MF1K

Hull-mounted surface ship sonars (

e.g.,

AN/SQS-53C and AN/SQS-60).

Kingfisher mode associated with MF1 sonars.

MF3

Hull-mounted submarine sonars (

e.g.,

AN/BQQ-10).

MF4

Helicopter-deployed dipping sonars (

e.g.,

AN/AQS-22).

MF5

Active acoustic sonobuoys (

e.g.,

DICASS).

MF6

Active underwater sound signal devices (

e.g.,

MK84).

MF8

Active sources (greater than 200 dB) not otherwise binned.

MF9

Active sources (equal to 180 dB and up to 200 dB) not otherwise binned.

MF10

Active sources (greater than 160 dB, but less than 180 dB) not otherwise binned.

MF11

Hull-mounted surface ship sonars with an active duty cycle greater than 80%.

MF12

Towed array surface ship sonars with an active duty cycle greater than 80%.

MF14

Oceanographic MF sonar.

High-Frequency (HF): Tactical and non-tactical sources that produce signals between 10-100 kHz

HF1

HF3

Hull-mounted submarine sonars (

e.g.,

AN/BQQ-10).

Other hull-mounted submarine sonars (classified).

HF4

Mine detection, classification, and neutralization sonar

(e.g.,

AQS-20).

HF5

Active sources (greater than 200 dB) not otherwise binned.

HF6

Active sources (equal to 180 dB and up to 200 dB) not otherwise binned.

HF7

Active sources (greater than 160 dB, but less than 180 dB) not otherwise binned.

HF8

Hull-mounted surface ship sonars (

e.g.,

AN/SQS-61).

Very High-Frequency Sonars (VHF): Non-tactical sources that produce signals between 100-200 kHz

VHF1

VHF sources greater than 200 dB.

Anti-Submarine Warfare (ASW): Tactical sources (

e.g.

, active sonobuoys and acoustic counter-measures systems) used during ASW training and testing activities

ASW1

ASW2

ASW3

MF systems operating above 200 dB.

MF Multistatic Active Coherent sonobuoy (

e.g.,

AN/SSQ-125).

MF towed active acoustic countermeasure systems (

e.g.,

AN/SLQ-25).

ASW4

MF expendable active acoustic device countermeasures (

e.g.,

MK 3).

ASW5

MF sonobuoys with high duty cycles.

Torpedoes (TORP): Source classes associated with the active acoustic signals produced by torpedoes

TORP1

TORP2

TORP3

Lightweight torpedo (

e.g.,

MK 46, MK 54, or Anti-Torpedo Torpedo).

Heavyweight torpedo (

e.g.,

MK 48).

Heavyweight torpedo (

e.g.,

MK 48).

Forward Looking Sonar (FLS): Forward or upward looking object avoidance sonars used for ship navigation and safety

FLS2

HF sources with short pulse lengths, narrow beam widths, and focused beam patterns.

Acoustic Modems (M): Systems used to transmit data through the water

M3

MF acoustic modems (greater than 190 dB).

Swimmer Detection Sonars (SD): Systems used to detect divers and submerged swimmers

SD1-SD2

HF and VHF sources with short pulse lengths, used for the detection of swimmers and other objects for the purpose of port security.

Synthetic Aperture Sonars (SAS): Sonars in which active acoustic signals are post-processed to form high-resolution images of the seafloor

SAS1

SAS2

SAS3

SAS4

MF SAS systems.

HF SAS systems.

VHF SAS systems.

MF to HF broadband mine countermeasure sonar.

Broadband Sound Sources (BB): Sonar systems with large frequency spectra, used for various purposes

BB1

BB2

BB4

BB5

BB6

BB7

MF to HF mine countermeasure sonar.

HF to VHF mine countermeasure sonar.

LF to MF oceanographic source.

LF to MF oceanographic source.

HF oceanographic source.

LF oceanographic source.

Notes:

ASW: Antisubmarine Warfare; BB: Broadband Sound Sources; FLS: Forward Looking Sonar; HF: High-Frequency; LF: Low-Frequency; M: Acoustic Modems; MF: Mid-Frequency; SAS: Synthetic Aperture Sonars; SD: Swimmer Detection Sonars; TORP: Torpedoes; VHF: Very High-Frequency.

Air Guns

Air guns are essentially stainless steel tubes charged with high-pressure air via a compressor. An impulsive sound is generated when the air is almost instantaneously released into the surrounding water. Small air guns with capacities up to 60 cubic inches (in

3

) would be used during testing activities in various offshore areas of the Southern California Range Complex and in the Hawaii Range Complex.

Generated impulses would have short durations, typically a few hundred milliseconds, with dominant frequencies below 1 kHz. The root-mean-square sound pressure level (SPL) and peak pressure (SPL peak) at a distance 1 m from the air gun would be approximately 215 dB re 1 μPa and 227 dB re 1 μPa, respectively, if operated at the full capacity of 60 in

3

. The size of the air gun chamber can be adjusted, which would result in lower SPLs and sound exposure level (SEL) per shot.

Pile Driving/Extraction

Impact pile driving and vibratory pile removal would occur during construction of an Elevated Causeway System (ELCAS), a temporary pier that allows the offloading of ships in areas without a permanent port. Construction of the elevated causeway could occur in sandy shallow water coastal areas at Silver Strand Training Complex and at Camp Pendleton, both in the Southern California Range Complex.

Installing piles for elevated causeways would involve the use of an impact hammer (impulsive) mechanism with both it and the pile held in place by a crane. The hammer rests on the pile, and the assemblage is then placed in position vertically on the beach or, when offshore, positioned with the pile in the water and resting on the seafloor. When the pile driving starts, the hammer part of the mechanism is raised up and allowed to fall, transferring energy to the top of the pile. The pile is thereby driven into the sediment by a repeated series of these hammer blows. Each blow results in an impulsive sound emanating from the length of the pile into the water column as well as from the bottom of the pile through the sediment. Because the impact wave travels through the steel pile at speeds faster than the speed of sound in water, a steep-fronted acoustic shock wave is formed in the water (note this shock wave has very low peak pressure compared to a shock wave from an explosive) (Reinhall and Dahl, 2011). An impact pile driver generally operates on average 35 blows per minute.

Pile removal involves the use of vibratory extraction (non-impulsive), during which the vibratory hammer is suspended from the crane and attached to the top of a pile. The pile is then vibrated by hydraulic motors rotating eccentric weights in the mechanism, causing a rapid up and down vibration in the pile. This vibration causes the sediment particles in contact with the pile to lose frictional grip on the pile. The crane slowly lifts up on the vibratory driver and pile until the pile is free of the sediment. Vibratory removal creates continuous non-impulsive noise at low source levels for a short duration.

The source levels of the noise produced by impact pile driving and vibratory pile removal from an actual ELCAS pile driving and removal are shown in Table 2.

Table 2—Elevated Causeway System Pile Driving and Removal Underwater Sound Levels

Pile size and type

Method

Average sound levels at 10 m

24-in. Steel Pipe Pile

Impact

1

192 dB re 1 μPa SPL rms.

182 dB re 1 μPa

2

s SEL (single strike).

24-in. Steel Pipe Pile

Vibratory

2

146 dB re 1 μPa SPL rms.

145 dB re 1 μPa

2

s SEL (per second of duration).

1

Illingworth and Rodkin (2016).

2

Illingworth and Rodkin (2015).

Notes:

in = inch, SEL = Sound Exposure Level, SPL = Sound Pressure Level, rms = root mean squared, dB re 1 μPa = decibels referenced to 1 micropascal.

In addition to underwater noise, the installation and removal of piles also results in airborne noise in the environment. Impact pile driving creates in-air impulsive sound about 100 dBA re 20 μPa at a range of 15 m (Illingworth and Rodkin, 2016). During vibratory extraction, the three aspects that generate airborne noise are the crane, the power plant, and the vibratory extractor. The average sound level recorded in air during vibratory extraction was about 85 dBA re 20 μPa (94 dB re 20 μPa) within a range of 10-15 m (Illingworth and Rodkin, 2015).

The size of the pier and number of piles used in an ELCAS event is approximately 1,520 ft long, requiring 119 supporting piles. Construction of the ELCAS would involve intermittent impact pile driving over approximately 20 days. Crews work 24 hours (hrs) a day and would drive approximately 6 piles in that period. Each pile takes about 15 minutes to drive with time taken between piles to reposition the driver. When training events that use the ELCAS are complete, the structure would be removed using vibratory methods over approximately 10 days. Crews would remove about 12 piles per 24-hour period, each taking about 6 minutes to remove.

Pile driving for ELCAS training would occur in shallower water, and sound could be transmitted on direct paths through the water, be reflected at the water surface or bottom, or travel through bottom substrate. Soft substrates such as sand bottom at the proposed ELCAS locations would absorb or attenuate the sound more readily than hard substrates (rock), which may reflect the acoustic wave. Most acoustic energy would be concentrated below 1,000 hertz (Hz) (Hildebrand, 2009).

Explosive Stressors

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 (Navy Activity Descriptions) of the HSTT DEIS/OEIS. Explanations of the terminology and metrics used when describing explosives in the Navy's rulemaking/LOA application are also in Appendix D (Acoustic and Explosive Concepts) of the HSTT DEIS/OEIS.

The near-instantaneous rise from ambient to an extremely high peak pressure is what makes an explosive shock wave potentially damaging. Farther from an explosive, the peak pressures decay and the explosive waves propagate as an impulsive, broadband sound. Several parameters influence the effect of an explosive: The weight of the explosive warhead, the type of explosive material, the boundaries and characteristics of the propagation medium, and, in water, the detonation depth. The net explosive weight, the explosive power of a charge expressed as the equivalent weight of trinitrotoluene (TNT), accounts for the first two parameters. The effects of these factors are explained in Appendix D (Acoustic and Explosive Concepts) of the HSTT DEIS/OEIS.

Explosions in Water

Explosive detonations during training and testing activities are associated with high-explosive munitions, including, but not limited to, bombs, missiles, rockets, naval gun shells, torpedoes, mines, demolition charges, and explosive sonobuoys. Explosive detonations during training and testing involving the use of high-explosive munitions (including bombs, missiles, and naval gun shells), could occur in the air or at the water's surface. Explosive detonations associated with torpedoes and explosive sonobuoys could occur in the water column; mines and demolition charges could be detonated in the water column or on the ocean bottom. Most detonations would occur in waters greater than 200 ft in depth, and greater than 3 nmi from shore, although most mine warfare, demolition, and some testing detonations would occur in shallow water close to shore. Those that occur close to shore are typically conducted on designated ranges.

In order to better organize and facilitate the analysis of explosives used by the Navy during training and testing that could detonate in water or at the water surface, explosive classification bins were developed. The use of explosive classification bins provides the same benefits as described for acoustic source classification bins in Section 1.4.1 (Acoustic Stressors) of the Navy's rulemaking/LOA application.

Explosives detonated in water are binned by net explosive weight. The bins of explosives that are proposed for use in the Study Area are shown in Table 3 below.

Table 3—Explosives Analyzed

Bin

Net explosive weight

1

(lb)

Example explosive source

E1

0.1-0.25

Medium-caliber projectile.

E2

>0.25-0.5

Medium-caliber projectile.

E3

>0.5-2.5

Large-caliber projectile.

E4

>2.5-5

Mine neutralization charge.

E5

>5-10

5-inch projectile.

E6

>10-20

Hellfire missile.

E7

>20-60

Demo block/shaped charge.

E8

>60-100

Light-weight torpedo.

E9

>100-250

500 lb. bomb.

E10

>250-500

Harpoon missile.

E11

>500-650

650 lb. mine.

E12

>650-1,000

2,000 lb. bomb.

E13

2

>1,000-1,740

Mat weave.

1

Net Explosive Weight refers to the equivalent amount of TNT.

2

E13 is not modeled for protected species impacts in water because most energy is lost into the air or to the bottom substrate due to detonation in very shallow water. In addition, activities are confined to small cove without regular marine mammal occurrence. These are not single charges, but multiple smaller charges detonated simultaneously or within a short time period.

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. Appendix D (Acoustic and Explosive Concepts) of the HSTT DEIS/OEIS explains the characteristics of explosive detonations and how the above factors affect the propagation of explosive energy in the water. 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 HSTT Study Area.

Explosive Fragments

Marine mammals could be exposed to fragments from underwater explosions associated with the specified activities. When explosive ordnance (

e.g.,

bomb or missile) detonates, fragments of the weapon are thrown at high-velocity from the detonation point, which can injure or kill marine mammals if they are struck. These fragments may be of variable size and are ejected at supersonic speed from the detonation. The casing fragments will be ejected at velocities much greater than debris from any target due to the proximity of the casing to the explosive material. Risk of fragment injury reduces exponentially with distance as the fragment density is reduced. Fragments underwater tend to be larger than fragments produced by in-air explosions (Swisdak and Montaro, 1992). Underwater, the friction of the water would quickly slow these fragments to a point where they no longer pose a threat. Opposingly, the blast wave from an explosive detonation moves efficiently through the seawater. Because the ranges to mortality and injury due to exposure to the blast wave are likely to far exceed the zone where fragments could injure or kill an animal, the threshold are assumed to encompass risk due to fragmentation.

Other Stressor—Vessel Strike

There is a very small chance that a vessel utilized in training or testing activities could strike a large whale. 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 a limited, sporadic, and incidental result of Navy vessel movement within the 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 potential 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 average speed of large Navy ships ranges between 10 and 15 knots (kn) and submarines generally operate at speeds in the range of 8-13 kn, while a few specialized vessels can travel at faster speeds. By comparison, this is slower than most commercial vessels where full speed for a container ship is typically 24 kn (Bonney and Leach, 2010). Additional information on Navy vessel movements is provided in the Specified Activities section.

The Center for Naval Analysis conducted studies to determine traffic patterns of Navy and non-Navy vessels in the HSTT Study Area (Mintz, 2016; Mintz and Filadelfo, 2011; Mintz, 2012; Mintz and Parker, 2006). The most recent analysis covered the 5-year period from 2011 to 2015 for vessels over 65 ft in length (Mintz, 2016). Categories of vessels included in the study were U.S. Navy surface ship traffic and non-military civilian traffic such as cargo vessels, bulk carriers, commercial fishing vessels, oil tankers, passenger vessels, tugs, and research vessels (Mintz, 2016). In the Hawaii Range Complex, civilian commercial shipping comprised 89 percent of total vessel traffic while Navy ship traffic accounted for eight percent (Mintz, 2016). In the Southern California Range Complex civilian commercial shipping comprised 96 percent of total vessel traffic while Navy ship traffic accounted for four percent (Mintz, 2016).

Navy ships transit at speeds that are optimal for fuel conservation or to meet training and testing requirements. Small craft (for purposes of this analysis, less than 18 m in length) have much more variable speeds (0-50+ kn, dependent on the activity). Submarines generally operate at speeds in the range of 8-13 kn. While these speeds are considered averages and representative of most events, some vessels need to operate outside of these parameters for certain times or during certain activities. 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; vessel boarding, search, and seizure training events; 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 events, including high-speed tests of newly constructed vessels, where vessels would operate at higher speeds.

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 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 safe 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.

Specified Activities

Proposed Training Activities

The Navy's Specified Activities are presented and analyzed as a representative year of training to account for the natural fluctuation of training cycles and deployment schedules that generally influences the actual level of training that occurs year after year in any five-year period. Using a representative level of activity rather than a maximum tempo of training activity in every year is more reflective of the amount of hull-mounted mid-frequency active sonar estimated to be necessary to meet training requirements. It also means that the Navy is requesting fewer hours of hull-mounted mid-frequency active sonar. Both unit-level training and major training exercises have been adjusted to meet this representative year, as discussed below. For the purposes of the Navy's rulemaking/LOA application, the Navy assumes that some unit-level training would be conducted using synthetic means (

e.g.,

simulators). Additionally, the Specified Activities analysis assumes that some unit-level active sonar training will be accounted for during the conduct of coordinated and major training exercises.

The Optimized Fleet Response Plan and various training plans identify the number and duration of training cycles that could occur over a five-year period. The Specified Activities considers fluctuations in training cycles and deployment schedules that do not follow a traditional annual calendar but instead are influenced by in-theater demands and other external factors. Similar to unit-level training, the Specified Activities does not analyze a maximum number carrier strike group Composite Training Unit Exercises (one type of major exercise) every year, but instead assumes a maximum number of exercises would occur during two years of any five-year period and that a lower number of exercises would occur in the other 3 years (described in Estimate Take section).

The training activities that the Navy proposes to conduct in the HSTT Study Area are summarized in Table 4. The table is organized according to primary mission areas and includes the activity name, associated stressors applicable to the Navy's rulemaking/LOA application, description of the activity, sound source bin, the locations of those activities in the HSTT Study Area, and the number of Specified Activities. For further information regarding the primary platform used (

e.g.,

ship or aircraft type) see Appendix A (Navy Activity Descriptions) of the HSTT DEIS/OEIS.

BILLING CODE 3510-22-P

EP26JN18.071

EP26JN18.072

EP26JN18.073

EP26JN18.074

EP26JN18.075

EP26JN18.076

EP26JN18.077

EP26JN18.078

EP26JN18.079

EP26JN18.080

Proposed Testing Activities

Testing activities covered in the Navy's rulemaking/LOA application are described in Table 5 through Table 8. The five-year Specified Activities presented here is based on the level of testing activities anticipated to be conducted into the reasonably foreseeable future, with adjustments that account for changes in the types and tempo (increases or decreases) of testing activities to meet current and future military readiness requirements. The Specified Activities includes the testing of new platforms, systems, and related equipment that will be introduced after December 2018 and during the period of the rule. The majority of testing activities that would be conducted under the Specified Activities are the same or similar as those conducted currently or in the past. The Specified Activities includes the testing of some new systems using new technologies and takes into account inherent uncertainties in this type of testing.

Under the Specified Activities, the Navy proposes a range of annual levels of testing that reflects the fluctuations in testing programs by recognizing that the maximum level of testing will not be conducted each year, but further indicates a five-year maximum for each activity that will not be exceeded. The Specified Activities contains a more realistic annual representation of activities, but includes years of a higher maximum amount of testing to account for these fluctuations.

The tables include the activity name, associated stressor(s), description of the activity, sound source bin, the areas where the activity is conducted, and the number of activities per year and per five years. Not all sound sources are used with each activity. Under the “Annual # of Activities” column, activities show either a single number or a range of numbers to indicate the number of times that activity could occur during any single year. The “5-Year # of Activities” is the maximum times an activity would occur over the 5-year period of this request. More detailed activity descriptions can be found in the HSTT DEIS/OEIS.

Naval Air Systems Command

Table 5 summarizes the proposed testing activities for the Naval Air Systems Command analyzed within the HSTT Study Area.

EP26JN18.081

EP26JN18.082

EP26JN18.083

Table 6 summarizes the proposed testing activities for the Naval Sea Systems Command analyzed within the HSTT Study Area.

EP26JN18.084

EP26JN18.085

EP26JN18.086

EP26JN18.087

Office of Naval Research

Table 7 summarizes the proposed testing activities for the Office of Naval Research analyzed within the HSTT Study Area.

EP26JN18.088

Space and Naval Warfare Systems Command

Table 8 summarizes the proposed testing activities for the Space and Naval Warfare Systems Command analyzed within the HSTT Study Area.

EP26JN18.089

Summary of Acoustic and Explosive Sources Analyzed for Training and Testing

Table 9 through Table 12 show the acoustic source classes and numbers, explosive source bins and numbers, air gun sources, and pile driving and removal activities associated with Navy training and testing activities in the HSTT Study Area that were analyzed in the Navy's rulemaking/LOA application. Table 9 shows the acoustic source classes (

i.e.,

LF, MF, and HF) that could occur in any year under the Specified Activities for training and testing activities. Under the Specified Activities, acoustic source class use would vary annually, consistent with the number of annual activities summarized above. The five-year total for the Specified Activities takes into account that annual variability.

EP26JN18.090

EP26JN18.091

EP26JN18.092

EP26JN18.093

BILLING CODE 3510-22-C

Table 10 shows the number of air guns shots proposed in the HSTT Study Area for training and testing activities.

Table 10—Training and Testing Air Gun Sources Quantitatively Analyzed in the HSTT Study Area

Source class category

Bin

Unit

1

Training

Annual

5-year total

Testing

Annual

5-year total

Air Guns (AG): Small underwater air guns

AG

C

0

0

844

4,220

1

C = count. One count (C) of AG is equivalent to 100 air gun firings.

Table 11 summarizes the impact pile driving and vibratory pile removal activities that would occur during a 24-hour period. Annually, for impact pile driving, the Navy will drive 119 piles, two times a year for a total of 238 piles. Over the 5-year period of the rule, the Navy will drive a total of 1190 piles by impact pile driving. Annually, for vibratory pile extraction, the Navy will extract 119 piles, two times a year for a total of 238 piles. Over the 5-year period of the rule, the Navy will extract a total of 1190 piles by vibratory pile extraction.

Table 11—Summary of Pile Driving and Removal Activities per 24-Hour Period in the HSTT Study Area

Method

Piles per

24-hour period

Time per pile

(minutes)

Total

estimated time

of noise per

24-hour period

(minutes)

Pile Driving (Impact)

6

15

90

Pile Removal (Vibratory)

12

6

72

Table 12 shows the number of in-water explosives that could be used in any year under the Specified Activities for training and testing activities. Under the Specified Activities, bin use would vary annually, consistent with the number of annual activities summarized above. The five-year total for the Specified Activities takes into account that annual variability.

Table 12—Explosive Source Bins Analyzed and Numbers Used During Training and Testing Activities in the HSTT Study Area

Bin

Net explosive

weight (lb)

Example explosive source

Modeled

underwater

detonation

depths (ft)

1

Training

Annual

5-year

total

Testing

Annual

5-year

total

E1

0.1-0.25

Medium-caliber projectiles

0.3, 60

2,940

14,700

8,916-15,216

62,880

E2

>0.25-0.5

Medium-caliber projectiles

0.3, 50

1,746

8,730

0

0

E3

>0.5-2.5

Large-caliber projectiles

0.3, 60

2,797

13,985

2,880-3,124

14,844

E4

>2.5-5

Mine neutralization charge

10, 16, 33, 50, 61, 65, 650

38

190

634-674

3,065

E5

>5-10

5 in projectiles

0.3, 10, 50

4,730-4,830

23,750

1,400

7,000

E6

>10-20

Hellfire missile

0.3, 10, 50, 60

592

2,872

26-38

166

E7

>20-60

Demo block/shaped charge

10, 50, 60

13

65

0

0

E8

>60-100

Lightweight torpedo

0.3, 150

33-88

170

57

285

E9

>100-250

500 lb bomb

0.3

410-450

2,090

4

20

E10

>250-500

Harpoon missile

0.3

219-224

1,100

30

150

E11

>500-650

650 lb mine

61, 150

7-17

45

12

60

E12

>650-1,000

2,000 lb bomb

0.3

16-21

77

0

0

E13

>1,000-1,740

Multiple Mat Weave charges

NA

2

9

45

0

0

1

Net Explosive Weight refers to the amount of explosives; the actual weight of a munition may be larger due to other components.

2

Not modeled because charge is detonated in surf zone; not a single E13 charge, but multiple smaller charges detonated in quick succession.

Notes:

in = inch(es), lb = pound(s), ft = feet.

Vessel Movement

Vessels used as part of the Specified Activities include ships, submarines, unmanned vessels, and boats ranging in size from small, 22 ft (7 m) rigid hull inflatable boats to aircraft carriers with lengths up to 1,092 ft (333 m). Large Navy ships greater than 60 ft (18 m) generally operate at speeds in the range of 10 to 15 kn for fuel conservation. Submarines generally operate at speeds in the range of 8 to 13 kn in transits and less than those speeds for certain tactical maneuvers. Small craft, less than 60 ft (18 m) in length, have much more variable speeds (dependent on the activity). Speeds generally range from 10 to 14 kn. While these speeds for large and small craft are representative of most events, some vessels need to temporarily operate outside of these parameters.

The number of Navy vessels used in the HSTT Study Area varies based on military training and testing requirements, deployment schedules, annual budgets, and other unpredictable factors. Most training and testing activities involve the use of vessels. These activities could be widely dispersed throughout the HSTT Study Area, but would be typically conducted near naval ports, piers, and range areas. Navy vessel traffic would especially be concentrated near San Diego, California and Pearl Harbor, Hawaii. There is no seasonal differentiation in Navy vessel use. The majority of large vessel traffic occurs between the installations and the OPAREAS. Support craft would be more concentrated in the coastal waters in the areas of naval installations, ports and ranges. Activities involving vessel movements occur intermittently and are variable in duration, ranging from a few hours up to two weeks.

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 a real-world situation and to their optimum capabilities. While standard operating procedures are designed for the safety of personnel and equipment and to ensure the success of training and testing activities, their implementation often yields additional benefits to environmental, socioeconomic, public health and safety, and cultural resources.

Navy standard operating procedures have been developed and refined over years of experience and are broadcast via numerous naval instructions and manuals, including, but not limited to:

• 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 instructions;

• 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; and

• International Regulations for Preventing Collisions at Sea.

Because standard operating procedures are essential to safety and mission success, the Navy considers them to be part of the Specified Activities, and has included them in the environmental analysis. Standard operating procedures that are recognized as providing a potential benefit to marine mammals during training and testing activities are noted below and discussed in more detail within the HSTT DEIS/OEIS.

• Vessel Safety

• Weapons Firing Safety

• Target Deployment Safety

• Towed In-Water Device Safety

• Pile Driving Safety

Standard operating procedures (which are implemented regardless of their secondary benefits) are different from mitigation measures (which are designed entirely for the purpose of avoiding or reducing potential impacts on the environment). Refer to Section 1.5.5 Standing Operating Procedures of the Navy's rulemaking/LOA application for greater detail.

Duration and Location

Training and testing activities would be conducted in the HSTT Study Area throughout the year from 2018 through 2023 for the five-year period covered by the regulations. The HSTT Study Area (see Figure 1.1-1 of the Navy's rulemaking/LOA application) is comprised of established operating and

warning areas across the north-central Pacific Ocean, from the mean high tide line in Southern California west to Hawaii and the International Date Line. The Study Area includes the at-sea areas of three existing range complexes (the Hawaii Range Complex, the SOCAL Range Complex, and the Silver Strand Training Complex), and overlaps a portion of the Point Mugu Sea Range (PMSR). Also included in the Study Area are Navy pierside locations in Hawaii and Southern California, Pearl Harbor, San Diego Bay, and the transit corridor

1

on the high seas where sonar training and testing may occur. A Navy range complex consists of geographic areas that encompasses a water component (above and below the surface), airspace, and may encompass a land component where training and testing of military platforms, tactics, munitions, explosives, and electronic warfare systems occur. Range complexes include OPAREAs and special use airspace, which may be further divided to provide better control of the area and events being conducted for safety reasons. Please refer to the regional maps provided in the Navy's rulemaking/LOA application (Figures 2-1 through 2-8) for additional detail of the range complexes and testing ranges. The range complexes and testing ranges are described in the following sections.

1

Vessel transit corridors are the routes typically used by Navy assets to traverse from one area to another. The route depicted in Figure 1-1 of the Navy's rulemaking/LOA application is the shortest route between Hawaii and Southern California, making it the quickest and most fuel efficient. Depicted vessel transit corridor is notional and may not represent the actual routes used by ships and submarines transiting from Southern California to Hawaii and back. Actual routes navigated are based on a number of factors including, but not limited to, weather, training, and operational requirements.

Hawaii Range Complex

The Hawaii Range Complex encompasses ocean areas located around the Hawaiian Islands chain. The ocean areas extend from 16 degrees north latitude to 43 degrees north latitude and from 150 degrees west longitude to the International Date Line, forming an area approximately 1,700 nmi by 1,600 nmi. The largest component of the Hawaii Range Complex is the Temporary OPAREA, extending north and west from the island of Kauai, and comprising over two million square nautical miles (nmi

2

) of air and sea space. The Temporary OPAREA is used primarily for missile testing by the Pacific Missile Range Facility (PMRF), and those missile tests are not part of the Navy's rulemaking/LOA application and are covered under other NEPA analysis. Other non-Navy entities such as various academic institutions and other Department of Defense agencies (DoD) such as the U.S. Air Force conduct activities in the PMRF. The PMRF activities referred to in the HSTT EIS/DEIS are very high altitude missile defense tests conducted by the Missile Defense Agency (MDA) (a non-Navy DoD command). For this rulemaking/LOA application, the area is used for Navy ship transits throughout the year. Despite the Temporary OPAREA's size, nearly all of the training and testing activities in the Hawaii Range Complex (HRC) take place within the smaller Hawaii OPAREA, that portion of the range complex immediately surrounding the island chain from Hawaii to Kauai (Figures 2-1 through 2-4 of the Navy's application). The Hawaii OPAREA consists of 235,000 nmi

2

of special use airspace and ocean areas. The HRC includes over 115,000 nmi

2

of combined special use airspace and air traffic control assigned airspace. As depicted in Figure 2-1 of the Navy's application, this airspace is almost entirely over the ocean and includes warning areas, air traffic controlled assigned airspace, and restricted areas.

The Hawaii Range Complex includes the ocean areas as described above, as well as specific training areas around the islands of Kauai, Oahu, and Maui (Figures 2-2, 2-3, and 2-4 respectively of the Navy's application). The Hawaii Range Complex also includes the ocean portion of the PMRF on Kauai, which is both a fleet training range and a fleet and DoD testing range. The facility includes 1,100 nmi

2

of instrumented ocean area at depths between 129 ft and 15,000 ft. The Hawaii Range Complex also includes the ocean areas around the designated Papahanaumokuakea Marine National Monument, referred hereafter as the Monument. Establishment of the Monument in June 2006 triggered a number of prohibitions on activities conducted in the Monument area. However, all military activities and exercises were specifically excluded from the listed prohibitions as long as the military exercises and activities are carried out in a manner that avoids, to the extent practicable and consistent with operational requirements, adverse impacts on monument resources and qualities. In 2016, the Monument was expanded from its original 139,818 square miles (mi

2

) to 582,578 mi

2

. The expansion of the Monument was primarily to the west—away from the portion of the Hawaii Range Complex where most training and testing activities are proposed to occur— and retained the military exclusion language contained in the monument designation.

Southern California Range Complex

The SOCAL Range Complex is located between Dana Point and San Diego, and extends southwest into the Pacific Ocean (Figures 2-5, 2-6, and 2-7 of the Navy's application). Although the range complex extends more than 600 nmi beyond land, most activities occur with 200 nmi of Southern California. The two primary components of the SOCAL Range Complex are the ocean OPAREAs and the special use airspace. These components encompass 120,000 nmi

2

of sea space and 113,000 nmi

2

of special use airspace. Most of the special use airspace in the SOCAL Range Complex is defined by W-291 (Figure 2-5 of the Navy's application). This warning area extends vertically from the ocean surface to 80,000 ft above mean sea level and encompasses 113,000 nmi

2

of airspace. The SOCAL Range Complex includes approximately 120,000 nmi

2

of sea and undersea space, largely defined as that ocean area underlying the Southern California special use airspace described above. The SOCAL Range Complex also extends beyond this airspace to include the surface and subsurface area from the northeastern border of W-291 to the coast of San Diego County, and includes San Diego Bay.

Point Mugu Sea Range Overlap

A small portion (approximately 1,000 nmi

2

) of the Point Mugu Sea Range is included in the HSTT Study Area (Figure 2-5 of the Navy's application). Only that part of the Point Mugu Sea Range is used by the Navy for anti-submarine warfare training. This training uses sonar, is conducted in the course of major training exercises, and is analyzed in this request.

Silver Strand Training Complex

The Silver Strand Training Complex is an integrated set of training areas located on and adjacent to the Silver Strand, a narrow, sandy isthmus separating the San Diego Bay from the Pacific Ocean. It is divided into two non-contiguous areas: Silver Strand Training Complex-North and Silver Strand Training Complex-South (Figure 2-8 of the Navy's application). The Silver Strand Training Complex-North includes 10 oceanside boat training lanes (numbered as Boat Lanes 1-10), ocean anchorage areas (numbered 101-178), bayside water training areas (Alpha through Hotel), and the Lilly Ann drop zone. The boat training lanes are each 500 yards (yd) wide stretching 4,000 yd seaward and forming a 5,000

yd long contiguous training area. The Silver Strand Training Complex-South includes four oceanside boat training lanes (numbered as Boat Lanes 11-14) and the TA-Kilo training area.

The anchorages lie offshore of Coronado in the Pacific Ocean and overlap a portion of Boat Lanes 1-10. The anchorages are each 654 yd in diameter and are grouped together in an area located primarily due west of Silver Strand Training Complex-North, east of Zuniga Jetty and the restricted areas on approach to the San Diego Bay entrance.

Ocean Operating Areas Outside the Bounds of Existing Range Complexes (Transit Corridor)

In addition to the range complexes that are part of the Study Area, a transit corridor outside the boundaries of the range complexes is also included as part of the Study Area in the analysis. Although not part of any defined range complex, this transit corridor is important to the Navy in that it provides adequate air, sea, and undersea space in which vessels and aircraft conduct training and some sonar maintenance and testing while enroute between Southern California and Hawaii. The transit corridor, notionally defined by the great circle route (

e.g.,

shortest distance) from San Diego to the center of the Hawaii Range Complex, as depicted in Figure 1-1 of the Navy's application, is generally used by ships transiting between the SOCAL Range Complex and Hawaii Range Complex. While in transit, ships and aircraft would, at times, conduct basic and routine unit level activities such as gunnery, bombing, and sonar training, testing, and maintenance, as long as the activities do not interfere with the primary objective of reaching their intended destination.

Pierside Locations, Pearl Harbor, and San Diego Bay

The Study Area includes select pierside locations where Navy surface ship and submarine sonar maintenance testing occur. For purposes of the Navy's application, pierside locations include channels and routes to and from Navy ports, and facilities associated with Navy ports and shipyards. These locations in the Study Area are located at Navy ports and naval shipyards in Pearl Harbor, Hawaii and in San Diego Bay, California (Figure 2-9 of the Navy's application). In addition, some training and testing activities occur throughout San Diego Bay.

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

Marine mammal species and their associated stocks that have the potential to occur in the HSTT Study Area are presented in Table 13 along with an abundance estimate, an associated coefficient of variation value, and best/minimum abundance estimates. The Navy proposes to take individuals of 39 marine mammal species by Level A and B harassment incidental to training and testing activities from the use of sonar and other transducers, in-water detonations, air guns, and impact pile driving/vibratory extraction activities. In addition, the Navy is requesting ten mortalities of two marine mammal stocks from explosives, and three takes of large whales by serious injury or mortality from vessel strikes over the five-year period. One marine mammal species, the Hawaiian monk seal, has critical habitat designated under the Endangered Species Act in the HSTT Study Area (described below).

Information on the status, distribution, abundance, population trends, and ecology of marine mammals in the HSTT Study Area may be found in Chapter 4 of the Navy's rulemaking/LOA application. Additional information on the general biology and ecology of marine mammals are included in the HSTT DEIS/OEIS. In addition, NMFS annually publishes Stock Assessment Reports (SARs) for all marine mammals in U.S. Exclusive Economic Zone (EEZ) waters, including stocks that occur within the HSTT Study Area and are found specifically in the U.S. Pacific Marine Mammal SAR (Carretta

et al.,

2017) (see

https://www.fisheries.noaa.gov/resource/document/us-pacific-marine-mammal-stock-assessments-2016

).

The species carried forward for analysis (and described in Table 13 below) are those likely to be found in the HSTT Study Area based on the most recent data available, and do not include stocks or species that may have once inhabited or transited the area but have not been sighted in recent years (

e.g.,

species which were extirpated because of factors such as nineteenth and twentieth century commercial exploitation). Extralimital species, species that would not be considered part of the HSTT seasonal species assemblage (

e.g.,

North Pacific right whale, any tropical odontocete species in SOCAL), were not included in the analysis.

Table 13—Marine Mammals Occurrence Within the HSTT Study Area

Common name

Scientific name

Stock

Status

MMPA

ESA

Occurrence

Seasonal absence

Stock abundance

(CV)/minimum

population

Blue whale

Balaenoptera musculus

Eastern North Pacific

Depleted

Endangered

Southern California

1,647 (0.07)/1,551

Central North Pacific

Depleted

Endangered

Hawaii

Summer

81 (1.14)/38

Bryde's whale

Balaenoptera brydei/edeni

Eastern Tropical Pacific

Southern California

unknown

Hawaiian

Depleted

Hawaii

798 (0.28)/633

Fin whale

Balaenoptera physalus

California, Oregon, and Washington

Depleted

Endangered

Southern California

9,029 (0.12)/8,127

Hawaiian

Depleted

Endangered

Hawaii

Summer

58 (1.12)/27

Gray whale

Eschrichtius robustus

Eastern North Pacific

Southern California

20,990 (0.05)/20,125

Western North Pacific

Depleted

Endangered

Southern California

140 (0.04)/135

Humpback whale

Megaptera novaeangliae

California, Oregon, and Washington

Depleted

Threatened/Endangered

1

Southern California

1,918 (0.03)/1,876

Central North Pacific

Hawaii

Summer

10,103 (0.30)/7,890

Minke whale

Balaenoptera acutorostrata

California, Oregon, and Washington

Southern California

636 (0.72)/369

Hawaiian

Hawaii

Summer

unknown

Sei whale

Balaenoptera borealis

Eastern North Pacific

Depleted

Endangered

Southern California

519 (0.4)/374

Hawaii

Depleted

Endangered

Hawaii

Summer

178 (0.90)/93

Sperm whale

Physeter macrocephalus

California, Oregon, and Washington

Depleted

Endangered

Southern California

2,106 (0.58)/1,332

Hawaiian

Depleted

Endangered

Hawaii

3,354 (0.34)/2,539

Pygmy sperm whale

Kogia breviceps

California, Oregon, and Washington

Southern California

Winter and Fall

4,111 (1.12)/1,924

Hawaiian

Hawaii

unknown

Dwarf sperm whale

Kogia sima

California, Oregon, and Washington

Southern California

unknown

Hawaiian

Hawaii

unknown

Baird's beaked whale

Berardius bairdii

California, Oregon, and Washington

Southern California

847 (0.81)/466

Blainville's beaked whale

Mesoplodon densirostris

Hawaiian

Hawaii

2,338 (1.13)/1,088

Cuvier's beaked whale

Ziphius cavirostris

California, Oregon, and Washington

Southern California

6,590 (0.55)/4,481

Hawaiian

Hawaii

1,941 na/1,142

Longman's beaked whale

Indopacetus pacificus

Hawaiian

Hawaii

4,571 (0.65)/2,773

Mesoplodon beaked whales

Mesoplodon spp.

California, Oregon, and Washington

Southern California

694 (0.65)/389

Common Bottlenose dolphin

Tursiops truncatus

California Coastal

California, Oregon, and Washington Offshore

Southern California

453 (0.06)/346

1,924 (0.54)/1,255

Hawaiian Pelagic

Hawain

5,950 (0.59)/3,755

Kauai and Niihau

Hawaii

184 (0.11)/168

Oahu

Hawaii

743 (0.54)/485

4-Islands

Hawaii

191 (0.24)/156

Hawaii Island

Hawaii

128 (0.13)/115

False killer whale

Pseudorca crassidens

Main Hawaiian Islands Insular

Depleted

Endangered

Hawaii

151 (0.20)/92

Hawaii Pelagic

Hawaii

1,540 (0.66)/928

Northwestern Hawaiian Islands

Hawaii

617 (1.11)/290

Fraser's dolphin

Lagenodelphis hosei

Hawaiian

Hawaii

16,992 (0.66)/10,241

Killer whale

Orcinus orca

Eastern North Pacific Offshore

Southern California

240 (0.49)/162

Eastern North Pacific Transient/West Coast Transient

2

Southern California

243 unknown/243

Hawaiian

Hawaii

101 (1.00)/50

Long-beaked common dolphin

Delphinus capensis

California

Southern California

101,305 (0.49)/68,432

Melon-headed whale

Peponocephala electra

Hawaiian Islands

Kohala Resident

Hawaii

5,794 (0.20)/4,904

447 (0.12)/404

Northern right whale dolphin

Lissodelphis borealis

California, Oregon, and Washington

Southern California

26,556 (0.44)/18,608

Pacific white-sided dolphin

Lagenorhynchus obliquidens

California, Oregon, and Washington

Southern California

26,814 (0.28)/21,195

Pantropical spotted dolphin

Stenella attenuata

Oahu

4-Islands

Hawaii

unknown

unknown

Hawaii Island

Hawaii

unknown

Hawaii Pelagic

Hawaii

15,917 (0.40)/11,508

Pygmy killer whale

Feresa attenuata

Tropical

Southern California

Winter & Spring

unknown

Hawaiian

Hawaii

3,433 (0.52)/2,274

Risso's dolphins

Grampus griseus

California, Oregon, and Washington

Southern California

6,336 (0.32)/4,817

Hawaiian

Hawaii

7,256 (0.41)/5,207

Rough-toothed dolphin

Steno bredanensis

na

3

Southern California

unknown

Hawaiian

Hawaii

6,288 (0.39)/4,581

Short-beaked common dolphin

Delphinus delphis

California, Oregon, and Washington

Southern California

969,861 (0.17)/839,325

Short-finned pilot whale

Globicephala macrorhynchus

California, Oregon, and Washington

Southern California

836 (0.79)/466

Hawaiian

Hawaii

12,422 (0.43)/8,782

Spinner dolphin

Stenella longirostris

Hawaii Pelagic

Hawaii Island

Hawaii

unknown

631 (0.04)/585

Oahu and 4-Islands

Hawaii

355 (0.09)/329

Kauai and Niihau

Hawaii

601 (0)/509

Kure and Midway

Hawaii

unknown

Pearl and Hermes

Hawaii

unknown

Striped dolphin

Stenella coeruleoalba

California, Oregon, and Washington

Southern California

29,211 (0.20)/24,782

Hawaiian

Hawaii

20,650 (0.36)/15,391

Dall's porpoise

Phocoenoides dalli

California, Oregon, and Washington

Southern California

25,750 (0.45)/17,954

Harbor seal

Phoca vitulina

California

Southern California

30,968 na/27,348

Hawaiian monk seal

Neomonachus schauinslandi

Hawaiian

Depleted

Endangered

Hawaii

1,272 na/1,205

Northern elephant seal

Mirounga angustirostris

California

Southern California

179,000 na/81,368

California sea lion

Zalophus californianus

U.S. Stock

Southern California

296,750 na/153,337

Guadalupe fur seal

Arctocephalus townsendi

Mexico to California

Depleted

Threatened

Southern California

20,000 na/15,830

Northern fur seal

Callorhinus ursinus

California

Southern California

14,050 na/7,524

Notes:

1

The two humpback whale Distinct Population Segments making up the California, Oregon, and Washington stock present in Southern California are the Mexico Distinct Population Segment, listed under ESA as Threatened, and the Central America Distinct Population Segment, which is listed under ESA as Endangered.

2

This stock is mentioned briefly in the Pacific Stock Assessment Report (Carretta

et al.,

2017) 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.,

2017).

3

Rough-toothed dolphin has a range known to include the waters off Southern California, but there is no recognized stock or data available for the U.S west coast.

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

Critical Habitat

Currently there is one marine mammal, the ESA-listed Hawaiian monk seal, with designated critical habitat within the HSTT Study Area. However, critical habitat for ESA-listed Main Hawaiian Islands insular false killer whale was recently proposed in November 2017 (82 FR 51186; November 3, 2017), designating waters from the 45 m depth contour to the 3200 m depth contour around the main Hawaiian Islands from Niihau east to Hawaii. However, some areas were proposed for exclusion based on considerations of economic and national security impacts.

Critical habitat for Hawaiian monk seals was designated in 1986 (51 FR 16047; April 30, 1986) and later revised in 1988 (53 FR 18988; May 26, 1988) and in 2015 (80 FR 50925; August 21, 2015) (NOAA, 2015a) (Figure 4-1 of the Navy's application). The essential features of the critical habitat were identified as: (1) Adjacent terrestrial and aquatic areas with characteristics preferred by monk seals for pupping and nursing; (2) shallow, sheltered aquatic areas adjacent to coastal locations preferred by monk seals for pupping and nursing; (3) marine areas from 0 to 500 m in depth preferred by juvenile and adult monk seals for foraging; (4) areas with low levels of anthropogenic disturbance; (5) marine areas with adequate prey quantity and quality; and (6) significant areas used by monk seals for hauling out, resting, or molting (NOAA, 2015a).

In the Northwestern Hawaiian Islands Hawaiian monk seal critical habitat includes all beach areas, sand spits and islets, including all beach crest vegetation to its deepest extent inland as well as the seafloor and marine habitat 10 m in height above the seafloor from the shoreline out to the 200 m depth contour around Kure Atoll, Midway Atoll, Pearl and Hermes Reef, Lisianski Island, Laysan Island, Maro Reef, Gardner Pinnacles, French Frigate Shoals, Necker Island and Nihoa Island. In the main Hawaiian Islands, Hawaiian monk seal critical habitat includes the seafloor and marine habitat to 10 m above the seafloor from the 200 m depth contour through the shoreline and extending into terrestrial habitat 5 m inland from the shoreline between identified boundary points around Kaula Island (includes marine habitat only, some excluded areas see areas, Niihau (includes marine habitat from 10 m-200 m in depth; some excluded areas), Kauai, Oahu, Maui Nui (including Kahoolawe, Lanai, Maui, and Molokai), Hawaii.

The approximate area encompassed by the Northwestern Hawaiian Islands was designated as the Papahanaumokuakea Monument in 2006, in part to protect the habitat of the Hawaiian monk seal. Hawaiian monk seals are managed as a single stock. There are six main reproductive subpopulations at: French Frigate Shoals, Laysan Island, Lisianski Island,

Pearl and Hermes Reef, Midway Island, and Kure Atoll in the northwestern Hawaiian Islands.

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 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

.

In Hawaii, 21 BIAs fall within or overlap with the HSTT Study Area. These include 11 small and resident population areas for species including dwarf sperm whales, Blainville's beaked whales, Cuvier's beaked whales, pygmy killer whales, short-finned pilot whales, melon-headed whales, false killer whales, pantropical spotted dolphins, spinner dolphins, rough-toothed dolphins, and common bottlenose dolphins (see Appendix K of the HSTT DEIS/OEIS for figures depicting these areas). In addition, six non-contiguous areas located adjacent to the eight main Hawaiian Islands have been designated as a humpback whale reproductive BIA (Baird

et al.,

2015c).

Five of the 28 BIAs that were identified for four species off the U.S. west coast (Calambokidis

et al.,

2015a) are located within or overlapping the SOCAL portion of the Study Area (see Appendix K of the HSTT DEIS/OEIS for figures depicting these areas). These identified areas include four feeding areas for blue whales and a migration area for gray whales (Calambokidis

et al.,

2015a).

Main Hawaiian Islands Humpback Whale Reproduction BIA

A single biologically important area around and between portions of eight islands was identified for breeding humpback whales in the Main Hawaiian Islands from December through April (Baird

et al.,

2015a) (see Figure K.3-1 of the HSTT DEIS/OEIS). The Main Hawaiian Islands Humpback Whale Reproduction BIA contains several humpback whale breeding sub-areas off the coasts of Kauai, Niihau, Oahu, Maui, and Hawaii Island. The highest densities of whales occur in waters that are less than 200 m in depth. The Main Hawaiian Islands Humpback Whale Reproduction Area also overlaps the Navy's 4-Islands Region and Hawaii Island Mitigation Areas and Humpback Whale Special Reporting Areas described later in this document (and also shown in Appendix K of the HSTT DEIS/OEIS). The Main Hawaiian Islands Humpback Whale Reproduction BIA also encompasses the entire Humpback Whale National Marine Sanctuary.

Dwarf Sperm Whales Small and Resident Population

A year-round BIA has been identified for a small resident population of dwarf sperm whales located off the island of Hawaii (Mahaffy

et al.,

2009; Baird

et al.,

2013a) with sightings between 500 and 1,000 m in depth (Baird et

al.,

2013a). This BIA also overlaps the Navy's Hawaii Island Mitigation Area described later in this document.

Blainville's Beaked Whales Small and Resident Population

A year-round BIA for a small resident population of Blainville's beaked whales has been identified off the island of Hawaii (McSweeney

et al.,

2007; Schorr

et al.,

2009a) with the highest density of groups in water between 500 and 1,500 m in depth, and density decreasing offshore (Baird

et al.,

2015c). This BIA also overlaps the Navy's Hawaii Island Mitigation Area described later in this document.

Cuvier's Beaked Whales Small and Resident Population

A year-round BIA for a small resident population of Cuvier's beaked whales has been identified off the island of Hawaii with the highest density of groups in water between 1,500 and 4,000 m in depth, and density decreasing offshore (Baird

et al.,

2015c). This BIA also mostly overlaps the Navy's Hawaii Island Mitigation Area described later in this document.

Pygmy Killer Whales Small and Resident Population

A year-round BIA for a small resident population of pygmy killer whales has been identified for the Hawaii Island resident population. This BIA includes the west side of the island of Hawaii, from northwest of Kawaihae south to the south point of the island, and along the southeast coast of the island. This BIA also overlaps the Navy's Hawaii Island Mitigation Area described later in this document.

Short-Finned Pilot Whales Small and Resident Population

A year- round BIA for a small resident population of short-finned pilot whales has been identified off the island of Hawaii (Baird

et al.,

2011c, 2013a; Mahaffy, 2012). Short-finned pilot whales are primarily connected to slope habitats off the islands, with the highest density between 1,000 and 2,500 m in depth, dropping off significantly after 2,500 m (Baird e

t al.,

2013a). This BIA also overlaps the Navy's Hawaii Island Mitigation Area described later in this document.

Melon-Headed Whales Small and Resident Population

A year-round BIA has been identified for a small and resident population of melon-headed whales off the island of Hawaii, primarily using the Kohala area. This BIA also overlaps the Navy's Hawaii Island Mitigation Area described later in this document.

False Killer Whales Small and Resident Population

A year-round BIA has been identified for a small and resident insular population of false killer whales off the coasts of Oahu, Maui, Molokai, Lanai, and Hawaii Island. The known range of this population extends from west of Niihau to east of Hawaii, out to 122 km offshore (Baird

et al.,

2012). This BIA also partially overlap the Navy's 4-Islands Region and Hawaii Island Mitigation Areas described later in this document.

Pantropical Spotted Dolphins Small and Resident Populations

Three year-round BIAs have been identified for small and resident populations of pantropical spotted dolphin. Three stocks of this species occurs around the main Hawaiian Islands (Oahu, the 4-Island Region, and off the main island of Hawaii). Two of these BIAs also overlap the Navy's 4-Islands Region and Hawaii Island Mitigation Areas described later in this document.

Spinner Dolphins Small and Resident Populations

Year-round BIAs have been identified for five small and resident populations of spinner dolphins. The boundaries of these populations are out to 10 nmi from shore around Kure and Midway Atolls, Pearl and Hermes Reef, Kauai and Niihau, Oahu and the 4-Islands Region and off the main island of Hawaii (Carretta

et al.,

2014). Two of these BIAs also overlap the Navy's 4-Islands Region and Hawaii Island Mitigation Areas described later in this document.

Rough-Toothed Dolphins Small and Resident Population

A year-round BIA has been identified for a small demographically isolated resident population off the island of Hawaii (Baird

et al.,

2008a; Albertson,

2015). This species is also found elsewhere among the Hawaiian Islands. The Navy's Hawaii Island Mitigation Area also overlaps with the majority of this BIA described later in this document.

Common Bottlenose Dolphins Small and Resident Populations

Year-round BIAs have been identified for the four insular stocks of bottlenose dolphins in Hawaiian waters. They are found both nearshore and offshore areas (Barlow, 2006), but around the main Hawaiian Islands they are primarily found in depths of less than 1,000 m (Baird

et al.,

2013a). The Navy's 4-Islands Region Mitigation Area overlaps portions of the BIA off of Molokai, Maui, and Lanai and the Hawaii Island Mitigation Area (described later in this document) includes the entire BIA off of the Island of Hawaii.

Blue Whale Feeding BIAs

There are nine feeding area BIAs identified for blue whales off the U.S. west coast (Calambokidis

et al.,

2015a), but only four overlap with the SOCAL portion of the HSTT Study Area (see Figure K.4-1 of the HSTT DEIS/OEIS). Two of these feeding areas (the Santa Monica Bay to Long Beach and the San Nicolas Island feeding area BIAs) are at the extreme northern edge and slightly overlap with the SOCAL portion of the HSTT Study Area. The remaining two feeding areas (the Tanner-Cortes Bank and the San Diego feeding area BIAs) are entirely within the SOCAL portion of the HSTT Study Area (Calambokidis

et al.,

2015a). The feeding behavior for which these areas are designated occurs from June to October (Aquatic Mammals, 2015; Calambokidis

et al.,

2015a). The San Diego blue whale feeding area overlaps with the Navy's San Diego Arc Mitigation Area as described later in this document.

Gray Whale Migration BIA

Calambokidis

et al.

(2015) identified a gray whale migration area off Southern California and overlapping with all the Southern California portion of the HSTT Study Area north of the border with Mexico (Figure K.4-7). This migration area covers approximately 22,300 km

2

of water space within the HSTT Study Area.

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 destroying, causing the loss of, or injuring any sanctuary resource managed under the law or regulations for that sanctuary (15 CFR part 922). NMS 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 Specified Activities are likely to destroy, cause the loss of, or injure a sanctuary resource. There are two national marine sanctuaries managed by the Office of National Marine Sanctuaries within the Study Area, the Hawaiian Islands Humpback Whale NMS and Channel Islands NMS (see Table 6.1-2 and Figures 6.1-3 and 6.1-4 of the HSTT DEIS/OEIS), which are described below.

Hawaiian Islands Humpback Whale NMS

The Hawaiian Islands Humpback Whale NMS is a single-species managed sanctuary, composed of 1,035 nmi

2

of the waters around Maui, Lanai, and Molokai; and smaller areas off the north shore of Kauai, off Hawaii's west coast, and off the north and southeast coasts of Oahu. The Sanctuary is entirely within the HRC of the HSTT Study Area and constitutes one of the world's most important Hawaii humpback whale Distinct Population Segment (DPS) habitats (81 FR 62259; September 8, 2016), and is a primary region for humpback reproduction in the United States (National Marine Sanctuaries Program, 2002). Scientists estimate that more than 50 percent of the entire North Pacific humpback whale population migrates to Hawaiian waters each winter to mate, calve, and nurse their young. The North Pacific humpback whale population has been split into two DPSs. The Hawaii humpback whale DPS migrates to Hawaiian waters each winter and is not listed under the ESA. In addition to protection under the MMPA, the Hawaii humpback whale DPS is protected in sanctuary waters by the Hawaiian Islands NMS. The sanctuary was created to protect humpback whales and shallow, protected waters important for calving and nursing (Office of National Marine Sanctuaries, 2010).

The Hawaiian Islands Humpback Whale NMS overlaps with the Main Hawaiian Islands Humpback Whale Reproduction Area (BIA) identified in Van Parijs (2015) and Baird et al. (2015) (shown in Figure K.3-1 of Appendix K and as discussed in Appendix K, Section K.3.1 (Main Hawaiian Islands Humpback Whale Reproduction Area of the HSTT DEIS/OEIS)).

Channel Islands 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. Only 92 nmi

2

, or about 8 percent of the sanctuary, occurs within the SOCAL portion of the Study Area (see Figure 6.1-4 of the HSTT DEIS/OEIS). The Study Area overlaps with the sanctuary at Santa Barbara Island. In addition, the Navy has proposed to implement the Santa Barbara Island Mitigation Area around Santa Barbara Island out to 6 nmi as described later in this document (also see Section K.2.2, Mitigation Areas to be Implemented of the HSTT DEIS/OEIS). As an ecosystem-based managed sanctuary, key habitats include kelp forest, surfgrass and eelgrass, intertidal zone, nearshore subtidal, deepwater benthic, and water column habitat. The diversity of habitats onshore and offshore contributes to the high species diversity in the Channel Islands NMS, with more than 195 species of birds, at least 33 species of cetaceans, 4 species of sea turtles, at least 492 species of algae and 4 species of sea grasses, a variety of invertebrates (including two endangered species (black abalone and the white abalone)), and 481 species of fish (NMS, 2009b).

Unusual Mortality Events (UME)

A UME is defined under Section 410(6) of the MMPA as a stranding that is unexpected; involves a significant die-off of any marine mammal population; and demands immediate response. From 1991 to the present, there have been 16 formally recognized UMEs affecting marine mammals in California and Hawaii and involving species under NMFS's jurisdiction. Two UMEs that could be relevant to informing the current analysis are discussed below. Specifically, the California sea lion UME in California is still open, but will be closed soon. The Guadalupe fur seal UME in California is still active and involves an ongoing investigation.

California Sea Lion UME

Elevated strandings of California sea lion pups began in Southern California in January 2013. In 2013, over 1,600 California sea lions stranded alive along the Southern California coastline and

over 3,500 live stranded California sea lions stranded on beaches in 2015, which was the highest number on record. Approximately 13,000 California sea lions (both live and dead) stranded from January 1, 2013, through December 31, 2017. Strandings in 2017 have finally returned to baseline (approximately 1,400/yr). The UME is currently defined to include pup and yearling California sea lions (0-2 years of age). Many of the sea lions were emaciated, dehydrated, and very underweight for their age. Findings to date indicate that a likely contributor to the large number of stranded, malnourished pups was a change in the availability of sea lion prey, especially sardines, a high value food source for both weaned pups and nursing mothers. Current data show changes in availability of sea lion prey in Southern California waters was likely a contributor to the UME, and this change was most likely secondary to ecological factors (El Niño and Warm Water Blob). Sardine spawning grounds shifted further offshore in 2012 and 2013, and while other prey were available (market squid and rockfish), these may not have provided adequate nutrition in the milk of sea lion mothers supporting pups or for newly-weaned pups foraging on their own. Although the pups showed signs of some viruses and infections, findings indicate that this event was not caused by disease, but rather by the lack of high quality, close-by food sources for nursing mothers and weaned pups. Current evidence does not support that this UME was caused by a single infectious agent, though a variety of disease-causing bacteria and viruses were found in samples from sea lion pups. This investigation will soon be closed. Please refer to

https://www.fisheries.noaa.gov/national/marine-life-distress/2013-2017-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 have remained well above average through 2017. As of March 8, 2018, the total number of Guadalupe fur seals to date in the UME is 241. Strandings are seasonal and generally peak in April through June of each year. The Guadalupe fur seal strandings have been mostly weaned pups and juveniles (1-2 years old) with both live and dead strandings occurring. Current findings from the majority of stranded animals include primary malnutrition with secondary bacterial and parasitic infections. This UME is occurring in the same area as the ongoing 2013-2017 California sea lion UME. This investigation is ongoing. Please refer to

https://www.fisheries.noaa.gov/national/marine-life-distress/2015-2018-guadalupe-fur-seal-unusual-mortality-event-california

for more information on this UME.

Marine Mammal Hearing

Hearing is the most important sensory modality for marine mammals underwater, and exposure to anthropogenic sound can have deleterious effects. To appropriately assess the potential effects of exposure to sound, it is necessary to understand the frequency ranges marine mammals are able to hear. Current data indicate that not all marine mammal species have equal hearing capabilities (

e.g.,

Richardson

et al.,

1995; Wartzok and Ketten, 1999; Au and Hastings, 2008). To reflect this, Southall

et al.

(2007) recommended that marine mammals be divided into functional hearing groups based on directly measured or estimated hearing ranges on the basis of available behavioral response data, audiograms derived using auditory evoked potential techniques, anatomical modeling, and other data. Note that no direct measurements of hearing ability have been successfully completed for mysticetes (

i.e.,

low-frequency cetaceans). Subsequently, NMFS (2016) described generalized hearing ranges for these marine mammal hearing groups. Generalized hearing ranges were chosen based on the approximately 65 dB threshold from the normalized composite audiograms, with the exception for lower limits for low-frequency cetaceans where the lower bound was deemed to be biologically implausible and the lower bound from Southall

et al.

(2007) retained. The functional groups and the associated frequencies are indicated below (note that these frequency ranges correspond to the range for the composite group, with the entire range not necessarily reflecting the capabilities of every species within that group):

• Low-frequency cetaceans (mysticetes): Generalized hearing is estimated to occur between approximately 7 Hz and 35 kHz;

• Mid-frequency cetaceans (larger toothed whales, beaked whales, and most delphinids): Generalized hearing is estimated to occur between approximately 150 Hz and 160 kHz;

• High-frequency cetaceans (porpoises, river dolphins, and members of the genera Kogia and Cephalorhynchus; including two members of the genus Lagenorhynchus, on the basis of recent echolocation data and genetic data): Generalized hearing is estimated to occur between approximately 275 Hz and 160 kHz;

• Pinnipeds in water; Phocidae (true seals): Generalized hearing is estimated to occur between approximately 50 Hz to 86 kHz; and

• Pinnipeds in water; Otariidae (eared seals): Generalized hearing is estimated to occur between 60 Hz and 39 kHz.

The pinniped functional hearing group was modified from Southall

et al.

(2007) on the basis of data indicating that phocid species have consistently demonstrated an extended frequency range of hearing compared to otariids, especially in the higher frequency range (Hemilä

et al.,

2006; Kastelein

et al.,

2009; Reichmuth and Holt, 2013).

For more detail concerning these groups and associated frequency ranges, please see NMFS (2016) for a review of available information.

Potential Effects of Specified Activities on Marine Mammals and Their Habitat

This section includes a summary and discussion 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 document includes a quantitative analysis of the number of instances of take that could occur from these activities. The “Negligible Impact Analysis and Determination” section considers the content of this section, the “Estimated Take of Marine Mammals” section, and the “Proposed Mitigation” section, to draw conclusions regarding the likely impacts of these activities on the reproductive success or survivorship of individuals and how those impacts on individuals are likely to impact marine mammal species or stocks.

The Navy has requested authorization for the take of marine mammals that may occur incidental to training and testing activities in the HSTT Study Area. The Navy analyzed potential impacts to marine mammals from acoustic and explosive sources as well as vessel strikes.

Other potential impacts to marine mammals from training and testing activities in the HSTT Study Area were analyzed in the HSTT DEIS/OEIS, in consultation with NMFS as a cooperating agency, and determined to be unlikely to result in marine mammal take. Therefore, the Navy has not requested authorization for take of marine mammals incidental to other components of their Specified Activities, and we agree that take is

unlikely to occur from those components. In this proposed rule, NMFS analyzes the potential effects on marine mammals from the activity components that may cause the take of marine mammals: Exposure to acoustic or explosive stressors including non-impulsive (sonar and other active acoustic sources) and impulsive (explosives, impact pile driving, and air guns) stressors, and vessel strikes.

For the purpose of MMPA incidental take authorizations, NMFS's effects assessments serve four primary purposes: (1) To prescribe the permissible methods of taking (

i.e.,

Level B harassment (behavioral harassment and temporary threshold shift (TTS), Level A harassment (permanent threshold shift (PTS) or non-auditory injury), serious injury, or mortality, including an 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 such species or stock and its habitat (

i.e.,

mitigation); (2) to determine whether the specified activities would have a negligible impact on the affected species or stocks of marine mammals (based on the likelihood that the activities would adversely affect the species or stock through effects on annual rates of recruitment or survival); (3) to determine whether the specified activities would have an unmitigable adverse impact on the availability of the species or stock(s) for subsistence uses (however, there are no subsistence communities that would be affected in the HSTT Study Area, so this determination is inapplicable to the HSTT rulemaking); and (4) to prescribe requirements pertaining to monitoring and reporting.

In the Potential Effects Section, NMFS provides a general description of the ways marine mammals may be affected by these activities in the form of mortality, physical trauma, sensory impairment (permanent and temporary threshold shifts and acoustic masking), physiological responses (particular stress responses), behavioral disturbance, or habitat effects. Explosives and vessel strikes, which have the potential to result in incidental take from serious injury and/or mortality, will be discussed in more detail in the Estimated Take of Marine Mammals section. The Estimated Take of Marine Mammals section also discusses how the potential effects on marine mammals from non-impulsive and impulsive sources relate to the MMPA definitions of Level A and Level B Harassment, and quantifies those effects that rise to the level of a take along with the potential effects from vessel strikes. The Negligible Impact Analysis Section assesses whether the proposed authorized take will have a negligible impact on the affected species and stocks.

Potential Effects of Underwater Sound

Note that, in the following discussion, we refer in many cases to a review article concerning studies of noise-induced hearing loss conducted from 1996-2015 (

i.e.,

Finneran, 2015). For study-specific citations, please see that work. Anthropogenic sounds cover a broad range of frequencies and sound levels and can have a range of highly variable impacts on marine life, from none or minor to potentially severe responses, depending on received levels, duration of exposure, behavioral context, and various other factors. The potential effects of underwater sound from active acoustic sources can possibly result in one or more of the following: temporary or permanent hearing impairment, non-auditory physical or physiological effects, behavioral disturbance, stress, and masking (Richardson

et al.,

1995; Gordon

et al.,

2004; Nowacek

et al.,

2007; Southall

et al.,

2007; Götz

et al.,

2009). The degree of effect is intrinsically related to the signal characteristics, received level, distance from the source, and duration of the sound exposure. In general, sudden, high level sounds can cause hearing loss, as can longer exposures to lower level sounds. Temporary or permanent loss of hearing will occur almost exclusively for noise within an animal's hearing range. We first describe specific manifestations of acoustic effects before providing discussion specific to the Navy's activities.

Richardson

et al.

(1995) described zones of increasing intensity of effect that might be expected to occur, in relation to distance from a source and assuming that the signal is within an animal's hearing range. First is the area within which the acoustic signal would be audible (potentially perceived) to the animal, but not strong enough to elicit any overt behavioral or physiological response. The next zone corresponds with the area where the signal is audible to the animal and of sufficient intensity to elicit behavioral or physiological responsiveness. Third is a zone within which, for signals of high intensity, the received level is sufficient to potentially cause discomfort or tissue damage to auditory systems. Overlaying these zones to a certain extent is the area within which masking (

i.e.,

when a sound interferes with or masks the ability of an animal to detect a signal of interest that is above the absolute hearing threshold) may occur; the masking zone may be highly variable in size.

We also describe more severe effects (

i.e.,

certain non-auditory physical or physiological effects). Potential effects from impulsive sound sources can range in severity from effects such as behavioral disturbance or tactile perception to physical discomfort, slight injury of the internal organs and the auditory system, or mortality (Yelverton

et al.,

1973). Non-auditory physiological effects or injuries that theoretically might occur in marine mammals exposed to high level underwater sound or as a secondary effect of extreme behavioral reactions (

e.g.,

change in dive profile as a result of an avoidance reaction) caused by exposure to sound include neurological effects, bubble formation, resonance effects, and other types of organ or tissue damage (Cox

et al.,

2006; Southall

et al.,

2007; Zimmer and Tyack, 2007; Tal

et al.,

2015).

Acoustic Sources

Direct Physiological Effects

Based on the literature, there are two basic ways that non-impulsive sources might directly result in direct physiological effects. Noise-induced loss of hearing sensitivity (more commonly-called “threshold shift” (TS)) is the better-understood of these two effects, and the only one that is actually expected to occur. The second effect, acoustically mediated bubble growth and other pressure-related physiological impacts are addressed briefly below, but are not expected to result from the Navy's activities. Separately, an animal's behavioral reaction to an acoustic exposure might lead to physiological effects that might ultimately lead to injury or death, which is discussed later in the Stranding Section.

Threshold Shift (Noise-Induced Loss of Hearing)

When animals exhibit reduced hearing sensitivity within their auditory range (

i.e.,

sounds must be louder for an animal to detect them) following exposure to a sufficiently intense sound or a less intense sound for a sufficient duration, it is referred to as a noise-induced TS. An animal can experience a TTS and/or PTS. TTS can last from minutes or hours to days (

i.e.,

there is recovery back to baseline/pre-exposure levels), can occur within a specific frequency range (

i.e.,

an animal might only have a temporary loss of hearing sensitivity within a limited frequency band of its auditory range), and can be

of varying amounts (for example, an animal's hearing sensitivity might be reduced by only 6 dB or reduced by 30 dB). Repeated sound exposure that leads to TTS could cause PTS. In severe cases of PTS, there can be total or partial deafness, while in most cases the animal has an impaired ability to hear sounds in specific frequency ranges (Kryter, 1985). When PTS occurs, there is physical damage to the sound receptors in the ear (

i.e.,

tissue damage), whereas TTS represents primarily tissue fatigue and is reversible (Southall

et al.,

2007). PTS is permanent (

i.e.,

there is incomplete recovery back to baseline/pre-exposure levels), but also can occur in a specific frequency range and amount as mentioned above for TTS. In addition, other investigators have suggested that TTS is within the normal bounds of physiological variability and tolerance and does not represent physical injury (

e.g.,

Ward, 1997). Therefore, NMFS does not consider TTS to constitute auditory injury.

The following physiological mechanisms are thought to play a role in inducing auditory TS: Effects to sensory hair cells in the inner ear that reduce their sensitivity; modification of the chemical environment within the sensory cells; residual muscular activity in the middle ear; displacement of certain inner ear membranes; increased blood flow; and post-stimulatory reduction in both efferent and sensory neural output (Southall

et al.,

2007). The amplitude, duration, frequency, temporal pattern, and energy distribution of sound exposure all can affect the amount of associated TS and the frequency range in which it occurs. Generally, the amount of TS, and the time needed to recover from the effect, increase as amplitude and duration of sound exposure increases. Human non-impulsive noise exposure guidelines are based on the assumption that exposures of equal energy (the same SEL) produce equal amounts of hearing impairment regardless of how the sound energy is distributed in time (NIOSH, 1998). Previous marine mammal TTS studies have also generally supported this equal energy relationship (Southall

et al.,

2007). However, some more recent studies concluded that for all noise exposure situations the equal energy relationship may not be the best indicator to predict TTS onset levels (Mooney

et al.,

2009a and 2009b; Kastak

et al.,

2007). These studies highlight the inherent complexity of predicting TTS onset in marine mammals, as well as the importance of considering exposure duration when assessing potential impacts. Generally, with sound exposures of equal energy, those that were quieter (lower SPL) with longer duration were found to induce TTS onset at lower levels than those of louder (higher SPL) and shorter duration. Less TS will occur from intermittent sounds than from a continuous exposure with the same energy (some recovery can occur between intermittent exposures) (Kryter

et al.,

1966; Ward, 1997; Mooney

et al.,

2009a, 2009b; Finneran

et al.,

2010). For example, one short but loud (higher SPL) sound exposure may induce the same impairment as one longer but softer (lower SPL) sound, which in turn may cause more impairment than a series of several intermittent softer sounds with the same total energy (Ward, 1997). Additionally, though TTS is temporary, very prolonged or repeated exposure to sound strong enough to elicit TTS, or shorter-term exposure to sound levels well above the TTS threshold can cause PTS, at least in terrestrial mammals (Kryter, 1985; Lonsbury-Martin

et al.,

1987).

PTS is considered auditory injury (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).

Although the published body of scientific literature contains numerous theoretical studies and discussion papers on hearing impairments that can occur with exposure to a loud sound, only a few studies provide empirical information on the levels at which noise-induced loss in hearing sensitivity occurs in nonhuman animals. The NMFS 2016 Acoustic Technical Guidance, which was used in the assessment of effects for this action, compiled, interpreted, and synthesized the best available scientific information for noise-induced hearing effects for marine mammals to derive updated thresholds for assessing the impacts of noise on marine mammal hearing, as noted above. For cetaceans, published data on the onset of TTS are limited to the captive bottlenose dolphin, beluga, harbor porpoise, and Yangtze finless porpoise (summarized in Finneran, 2015). TTS studies involving exposure to other Navy activities (

e.g.,

SURTASS LFA) or other low-frequency sonar (below 1 kHz) have never been conducted due to logistical difficulties of conducting experiments with low frequency sound sources. However, there are TTS measurements for exposures to other LF sources, such as seismic air guns. Finneran

et al.

(2015) suggest that the potential for air guns to cause hearing loss in dolphins is lower than previously predicted, perhaps as a result of the low-frequency content of air gun impulses compared to the high-frequency hearing ability of dolphins. Finneran

et al.

(2015) measured hearing thresholds in three captive bottlenose dolphins before and after exposure to ten pulses produced by a seismic air gun in order to study TTS induced after exposure to multiple pulses. Exposures began at relatively low levels and gradually increased over a period of several months, with the highest exposures at peak SPLs from 196 to 210 dB and cumulative (unweighted) SELs from 193-195 dB. No substantial TTS was observed. In addition, behavioral reactions were observed that indicated that animals can learn behaviors that effectively mitigate noise exposures (although exposure patterns must be learned, which is less likely in wild animals than for the captive animals considered in the study). The authors note that the failure to induce more significant auditory effects was likely due to the intermittent nature of exposure, the relatively low peak pressure produced by the acoustic source, and the low-frequency energy in air gun pulses as compared with the frequency range of best sensitivity for dolphins and other mid-frequency cetaceans. For pinnipeds in water, measurements of TTS are limited to harbor seals, elephant seals, and California sea lions (summarized in Finneran, 2015).

Marine mammal hearing plays a critical role in communication with conspecifics and in interpretation of environmental cues for purposes such as predator avoidance and prey capture. Depending on the degree (elevation of threshold in dB), duration (

i.e.,

recovery time), and frequency range of TTS, and the context in which it is experienced, TTS can have effects on marine mammals ranging from discountable to serious similar to those discussed in auditory masking, below. For example, a marine mammal may be able to readily compensate for a brief, relatively small amount of TTS in a non-critical frequency range that takes place during a time when the animal is traveling through the open ocean, where ambient noise is lower and there are not as many competing sounds present. Alternatively, a larger amount and longer duration of TTS sustained during a time when communication is critical for successful mother/calf interactions could have more serious impacts if it

were in the same frequency band as the necessary vocalizations and of a severity that impeded communication. The fact that animals exposed to high levels of sound that would be expected to result in this physiological response would also be expected to have behavioral responses of a comparatively more severe or sustained nature is potentially more significant than simple existence of a TTS. However, it is important to note that TTS could occur due to longer exposures to sound at lower levels so that a behavioral response may not be elicited.

Depending on the degree and frequency range, the effects of PTS on an animal could also range in severity, although it is considered generally more serious than TTS because it is a permanent condition. Of note, reduced hearing sensitivity as a simple function of aging has been observed in marine mammals, as well as humans and other taxa (Southall

et al.,

2007), so we can infer that strategies exist for coping with this condition to some degree, though likely not without some cost to the animal.

Acoustically Mediated Bubble Growth and Other Pressure-Related Injury

One theoretical cause of injury to marine mammals is rectified diffusion (Crum and Mao, 1996), the process of increasing the size of a bubble by exposing it to a sound field. This process could be facilitated if the environment in which the ensonified bubbles exist is supersaturated with gas. Repetitive diving by marine mammals can cause the blood and some tissues to accumulate gas to a greater degree than is supported by the surrounding environmental pressure (Ridgway and Howard, 1979). The deeper and longer dives of some marine mammals (for example, beaked whales) are theoretically predicted to induce greater supersaturation (Houser

et al.,

2001b). If rectified diffusion were possible in marine mammals exposed to high-level sound, conditions of tissue supersaturation could theoretically speed the rate and increase the size of bubble growth. Subsequent effects due to tissue trauma and emboli would presumably mirror those observed in humans suffering from decompression sickness.

It is unlikely that the short duration (in combination with the source levels) of sonar pings would be long enough to drive bubble growth to any substantial size, if such a phenomenon occurs. However, an alternative but related hypothesis has also been suggested: Stable bubbles could be destabilized by high-level sound exposures such that bubble growth then occurs through static diffusion of gas out of the tissues. In such a scenario the marine mammal would need to be in a gas-supersaturated state for a long enough period of time for bubbles to become of a problematic size. Recent research with

ex vivo

supersaturated bovine tissues suggested that, for a 37 kHz signal, a sound exposure of approximately 215 dB referenced to (re) 1 μPa would be required before microbubbles became destabilized and grew (Crum

et al.,

2005). Assuming spherical spreading loss and a nominal sonar source level of 235 dB re 1 μPa at 1 m, a whale would need to be within 10 m (33 ft) of the sonar dome to be exposed to such sound levels. Furthermore, tissues in the study were supersaturated by exposing them to pressures of 400-700 kilopascals for periods of hours and then releasing them to ambient pressures. Assuming the equilibration of gases with the tissues occurred when the tissues were exposed to the high pressures, levels of supersaturation in the tissues could have been as high as 400-700 percent. These levels of tissue supersaturation are substantially higher than model predictions for marine mammals (Houser

et al.,

2001; Saunders

et al.,

2008). It is improbable that this mechanism is responsible for stranding events or traumas associated with beaked whale strandings because both the degree of supersaturation and exposure levels observed to cause microbubble destabilization are unlikely to occur, either alone or in concert.

Yet another hypothesis (decompression sickness) has speculated that rapid ascent to the surface following exposure to a startling sound might produce tissue gas saturation sufficient for the evolution of nitrogen bubbles (Jepson

et al.,

2003; Fernandez

et al.,

2005; Fernández

et al.,

2012). In this scenario, the rate of ascent would need to be sufficiently rapid to compromise behavioral or physiological protections against nitrogen bubble formation. Alternatively, Tyack

et al.

(2006) studied the deep diving behavior of beaked whales and concluded that: “Using current models of breath-hold diving, we infer that their natural diving behavior is inconsistent with known problems of acute nitrogen supersaturation and embolism.” Collectively, these hypotheses can be referred to as “hypotheses of acoustically mediated bubble growth.”

Although theoretical predictions suggest the possibility for acoustically mediated bubble growth, there is considerable disagreement among scientists as to its likelihood (Piantadosi and Thalmann, 2004; Evans and Miller, 2003; Cox

et al.,

2006; Rommel

et al.,

2006). Crum and Mao (1996) hypothesized that received levels would have to exceed 190 dB in order for there to be the possibility of significant bubble growth due to supersaturation of gases in the blood (

i.e.,

rectified diffusion). Work conducted by Crum

et al.

(2005) demonstrated the possibility of rectified diffusion for short duration signals, but at SELs and tissue saturation levels that are highly improbable to occur in diving marine mammals. To date, energy levels (ELs) predicted to cause in vivo bubble formation within diving cetaceans have not been evaluated (NOAA, 2002b). Jepson

et al.

(2003, 2005) and Fernandez

et al.

(2004, 2005, 2012) concluded that in vivo bubble formation, which may be exacerbated by deep, long-duration, repetitive dives may explain why beaked whales appear to be relatively vulnerable to MF/HF sonar exposures. It has also been argued that traumas from some beaked whale strandings are consistent with gas emboli and bubble-induced tissue separations (Jepson

et al.,

2003); however, there is no conclusive evidence of this (Rommel

et al.,

2006).

In 2009, Hooker

et al.

tested two mathematical models to predict blood and tissue tension N2 (P

N2

) using field data from three beaked whale species: northern bottlenose whales, Cuvier's beaked whales, and Blainville's beaked whales. The researchers aimed to determine if physiology (body mass, diving lung volume, and dive response) or dive behavior (dive depth and duration, changes in ascent rate, and diel behavior) would lead to differences in P

N2

levels and thereby decompression sickness risk between species.

In their study, they compared results for previously published time depth recorder data (Hooker and Baird, 1999; Baird

et al.,

2006, 2008) from Cuvier's beaked whale, Blainville's beaked whale, and northern bottlenose whale. They reported that diving lung volume and extent of the dive response had a large effect on end-dive P

N2

. Also, results showed that dive profiles had a larger influence on end-dive P

N2

than body mass differences between species. Despite diel changes (

i.e.,

variation that occurs regularly every day or most days) in dive behavior, P

N2

levels showed no consistent trend. Model output suggested that all three species live with tissue P

N2

levels that would cause a significant proportion of decompression sickness cases in terrestrial mammals. The authors concluded that the dive behavior of Cuvier's beaked whale was different from both Blainville's beaked whale, and northern bottlenose whale,

and resulted in higher predicted tissue and blood N2 levels (Hooker

et al.,

2009) and suggested that the prevalence of Cuvier's beaked whales stranding after naval sonar exercises could be explained by either a higher abundance of this species in the affected areas or by possible species differences in behavior and/or physiology related to MF active sonar (Hooker

et al.,

2009).

Bernaldo de Quiros

et al.

(2012) showed that, among stranded whales, deep diving species of whales had higher abundances of gas bubbles compared to shallow diving species. Kvadsheim

et al.

(2012) estimated blood and tissue P

N2

levels in species representing shallow, intermediate, and deep diving cetaceans following behavioral responses to sonar and their comparisons found that deep diving species had higher end-dive blood and tissue N

2

levels, indicating a higher risk of developing gas bubble emboli compared with shallow diving species. Fahlmann

et al.

(2014) evaluated dive data recorded from sperm, killer, long-finned pilot, Blainville's beaked and Cuvier's beaked whales before and during exposure to low, as defined by the authors, (1-2 kHz) and mid (2-7 kHz) frequency active sonar in an attempt to determine if either differences in dive behavior or physiological responses to sonar are plausible risk factors for bubble formation. The authors suggested that CO

2

may initiate bubble formation and growth, while elevated levels of N

2

may be important for continued bubble growth. The authors also suggest that if CO

2

plays an important role in bubble formation, a cetacean escaping a sound source may experience increased metabolic rate, CO

2

production, and alteration in cardiac output, which could increase risk of gas bubble emboli. However, as discussed in Kvadsheim

et al.

(2012), the actual observed behavioral responses to sonar from the species in their study (sperm, killer, long-finned pilot, Blainville's beaked, and Cuvier's beaked whales) did not imply any significantly increased risk of decompression sickness due to high levels of N

2.

Therefore, further information is needed to understand the relationship between exposure to stimuli, behavioral response (discussed in more detail below), elevated N

2

levels, and gas bubble emboli in marine mammals. The hypotheses for gas bubble formation related to beaked whale strandings is that beaked whales potentially have strong avoidance responses to MF active sonars because they sound similar to their main predator, the killer whale (Cox

et al.,

2006; Southall

et al.,

2007; Zimmer and Tyack, 2007; Baird

et al.,

2008; Hooker

et al.,

2009). Further investigation is needed to assess the potential validity of these hypotheses.

To summarize, while there are several hypotheses, there is little data to support the potential for strong, anthropogenic underwater sounds to cause non-auditory physical effects in marine mammals. The available data do not support identification of a specific exposure level above which non-auditory effects can be expected (Southall

et al.,

2007) or any meaningful quantitative predictions of the numbers (if any) of marine mammals that might be affected in these ways. In addition, such effects, if they occur at all, would be expected to be limited to situations where marine mammals were exposed to high powered sounds at very close range over a prolonged period of time, which is not expected to occur based on the speed of the vessels operating sonar in combination with the speed and behavior of marine mammals in the vicinity of sonar.

Acoustic 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, 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. 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.

In humans, significant masking of tonal signals occurs as a result of exposure to noise in a narrow band of similar frequencies. As the sound level increases, though, the detection of frequencies above those of the masking stimulus decreases also. This principle is expected to apply to marine mammals as well because of common biomechanical cochlear properties across taxa.

Under certain circumstances, marine mammals experiencing significant masking could also be impaired from maximizing their performance fitness in survival and reproduction. Therefore, when the coincident (masking) sound is man-made, it may be considered harassment when disrupting or altering critical behaviors. It is important to distinguish TTS and PTS, which persist after the sound exposure from masking, which occurs during the sound exposure. Because masking (without resulting in TS) is not associated with abnormal physiological function, it is not considered a physiological effect, but rather a potential behavioral effect.

The frequency range of the potentially masking sound is important in determining any potential behavioral impacts. For example, low-frequency signals may have less effect on high-frequency echolocation sounds produced by odontocetes but are more likely to affect detection of mysticete communication calls and other potentially important natural sounds such as those produced by surf and some prey species. The masking of communication signals by anthropogenic noise may be considered as a reduction in the communication space of animals (

e.g.,

Clark

et al.,

2009; Matthews

et al.,

2016) and may result in energetic or other costs as animals change their vocalization behavior (

e.g.,

Miller

et al.,

2000; Foote

et al.,

2004; Parks

et al.,

2007; Di Iorio and Clark, 2009; Holt

et al.,

2009). Masking can be reduced in situations where the signal and noise come from different directions (Richardson

et al.,

1995), through amplitude modulation of the signal, or through other compensatory behaviors (Houser and Moore, 2014). Masking can be tested directly in captive species (

e.g.,

Erbe, 2008), but in wild populations it must be either modeled or inferred from evidence of masking compensation. There are few studies addressing real-world masking sounds likely to be experienced by marine mammals in the wild (

e.g.,

Branstetter

et al.,

2013).

Masking affects both senders and receivers of acoustic signals and can potentially have long-term chronic effects on marine mammals at the population level as well as at the individual level. Low-frequency ambient sound levels have increased by as much as 20 dB (more than three times in terms of SPL) in the world's ocean

from pre-industrial periods, with most of the increase from distant commercial shipping (Hildebrand, 2009). All anthropogenic sound sources, but especially chronic and lower-frequency signals (

e.g.,

from commercial vessel traffic), contribute to elevated ambient sound levels, thus intensifying masking.

Richardson

et al.

(1995b) argued that the maximum radius of influence of an industrial noise (including broadband low-frequency sound transmission) on a marine mammal is the distance from the source to the point at which the noise can barely be heard. This range is determined by either the hearing sensitivity of the animal or the background noise level present. Industrial masking is most likely to affect some species' ability to detect communication calls and natural sounds (

i.e.,

surf noise, prey noise, etc.; Richardson

et al.,

1995).

The echolocation calls of toothed whales are subject to masking by high-frequency sound. Human data indicate low-frequency sound can mask high-frequency sounds (

i.e.,

upward masking). Studies on captive odontocetes by Au

et al.

(1974, 1985, 1993) indicate that some species may use various processes to reduce masking effects (

e.g.,

adjustments in echolocation call intensity or frequency as a function of background noise conditions). There is also evidence that the directional hearing abilities of odontocetes are useful in reducing masking at the high-frequencies these cetaceans use to echolocate, but not at the low-to-moderate frequencies they use to communicate (Zaitseva

et al.,

1980). A study by Nachtigall and Supin (2008) showed that false killer whales adjust their hearing to compensate for ambient sounds and the intensity of returning echolocation signals. Holt

et al.

(2009) measured killer whale call source levels and background noise levels in the one to 40 kHz band and reported that the whales increased their call source levels by one dB SPL for every one dB SPL increase in background noise level. Similarly, another study on St. Lawrence River belugas reported a similar rate of increase in vocalization activity in response to passing vessels (Scheifele

et al.,

2005).

Parks

et al.

(2007) provided evidence of behavioral changes in the acoustic behaviors of the endangered North Atlantic right whale, and the South Atlantic southern right whale, and suggested that these were correlated to increased underwater noise levels. The study indicated that right whales might shift the frequency band of their calls to compensate for increased in-band background noise. The significance of their result is the indication of potential species-wide behavioral change in response to gradual, chronic increases in underwater ambient noise. Di Iorio and Clark (2010) showed that blue whale calling rates vary in association with seismic sparker survey activity, with whales calling more on days with survey than on days without surveys. They suggested that the whales called more during seismic survey periods as a way to compensate for the elevated noise conditions.

Risch

et al.

(2012) documented reductions in humpback whale vocalizations in the Stellwagen Bank National Marine Sanctuary concurrent with transmissions of the Ocean Acoustic Waveguide Remote Sensing (OAWRS) low-frequency fish sensor system at distances of 200 km (124 mi) from the source. The recorded OAWRS produced a series of frequency modulated pulses and the signal received levels ranged from 88 to 110 dB re: 1 μPa (Risch,

et al.,

2012). The authors hypothesized that individuals did not leave the area but instead ceased singing and noted that the duration and frequency range of the OAWRS signals (a novel sound to the whales) were similar to those of natural humpback whale song components used during mating (Risch

et al.,

2012). Thus, the novelty of the sound to humpback whales in the Navy's Study Area (Navy's Atlantic Fleet Study Area) provided a compelling contextual probability for the observed effects (Risch

et al.,

2012). However, the authors did not state or imply that these changes had long-term effects on individual animals or populations (Risch

et al.,

2012).

Redundancy and context can also facilitate detection of weak signals. These phenomena may help marine mammals detect weak sounds in the presence of natural or manmade noise. Most masking studies in marine mammals present the test signal and the masking noise from the same direction. The dominant background noise may be highly directional if it comes from a particular anthropogenic source such as a ship or industrial site. Directional hearing may significantly reduce the masking effects of these sounds by improving the effective signal-to-noise ratio.

The functional hearing ranges of mysticetes, odontocetes, and pinnipeds underwater all overlap the frequencies of the sonar sources used in the Navy's low-frequency active sonar (LFAS)/mid-frequency active sonar (MFAS)/high-frequency active sonar (HFAS) training and testing exercises. Additionally, almost all species' vocal repertoires span across the frequencies of these sonar sources used by the Navy. The closer the characteristics of the masking signal to the signal of interest, the more likely masking is to occur. Although hull-mounted sonar accounts for a large portion of the area ensonified by Navy activities (because of the source strength and number of hours it is conducted), the pulse length and low duty cycle of the MFAS/HFAS signal makes it less likely that masking would occur as a result.

Impaired Communication

In addition to making it more difficult for animals to perceive acoustic cues in their environment, anthropogenic sound presents separate challenges for animals that are vocalizing. When they vocalize, animals are aware of environmental conditions that affect the “active space” of their vocalizations, which is the maximum area within which their vocalizations can be detected before it drops to the level of ambient noise (Brenowitz, 2004; Brumm

et al.,

2004; Lohr

et al.,

2003). Animals are also aware of environmental conditions that affect whether listeners can discriminate and recognize their vocalizations from other sounds, which is more important than simply detecting that a vocalization is occurring (Brenowitz, 1982; Brumm

et al.,

2004; Dooling, 2004, Marten and Marler, 1977; Patricelli

et al.,

2006). Most species that vocalize have evolved with an ability to make adjustments to their vocalizations to increase the signal-to-noise ratio, active space, and recognizability/distinguishability of their vocalizations in the face of temporary changes in background noise (Brumm

et al.,

2004; Patricelli

et al.,

2006). Vocalizing animals can make adjustments to vocalization characteristics such as the frequency structure, amplitude, temporal structure, and temporal delivery.

Many animals wil

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