Takes of Marine Mammals Incidental to Specified Activities; U.S. Navy Training and Testing Activities in the Northwest Training and Testing Study Area

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DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration 50 CFR Part 218 [Docket No. 140109018-5464-01] RIN 0648-BD89 Takes of Marine Mammals Incidental to Specified Activities; U.S. Navy Training and Testing Activities in the Northwest 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 Northwest Training and Testing (NWTT) study area from November 2015 through November 2020. Pursuant to the Marine Mammal Protection Act (MMPA), NMFS is requesting comments on its proposal to issue regulations and subsequent Letters of Authorization (LOAs) to the Navy to incidentally harass marine mammals. The Navy has also requested that NMFS authorize modifications to watchstander requirements for observed behavior of marine mammals during Major Training Events (MTEs) in the Hawaii-Southern California Training and Testing (HSTT), Atlantic Fleet Training and Testing (AFTT), Mariana Islands Training and Testing (MITT), and Gulf of Alaska Training (GOA) study areas. Modifications to the Navy watchstander requirements would require a revision to regulatory text in current regulations governing the taking and importing of marine mammals during testing and/or training activities in these study areas. There are no MTEs associated with Navy training and testing activities in the NWTT study area.

DATES:

Comments and information must be received no later than July 17, 2015

to the Navy watchstander requirements would require a revision to regulatory text in current regulations governing the taking and importing of marine mammals during testing and/or training activities in these study areas. There are no MTEs associated with Navy training and testing activities in the NWTT study area.

DATES:

Comments and information must be received no later than July 17, 2015.

ADDRESSES:

You may submit comments, identified by NOAA-NMFS-2015-0031, 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-2015-0031, 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 will be publicly accessible. NMFS will accept anonymous comments (enter “N/A” in the required fields if you wish to remain anonymous). Attachments to electronic comments will be accepted in Microsoft Word, Excel, or Adobe PDF file formats only.

FOR FURTHER INFORMATION CONTACT:

John Fiorentino, Office of Protected Resources, NMFS, (301) 427-8477

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

FOR FURTHER INFORMATION CONTACT:

John Fiorentino, Office of Protected Resources, NMFS, (301) 427-8477.

SUPPLEMENTARY INFORMATION:

Availability

A copy of the Navy's LOA application, which contains a list of the references used in this document, may be obtained by visiting the internet at: http://www.nmfs.noaa.gov/pr/permits/incidental/military.htm. The Navy also prepared a Draft Environmental Impact Statement (DEIS)/Overseas Environmental Impact Statement (OEIS) to assess the environmental impacts associated with ongoing and proposed training and testing activities in the NWTT Study Area. The NWTT DEIS/OEIS was released to the public on January 24, 2014 (79 FR 4158) for review until April 15, 2014. On October 24, 2014 (79 FR 63610), the Navy published a Notice of Intent (NOI) to prepare a Supplement to the January 2014 NWTT DEIS/OEIS. The Supplement was released to the public on December 19, 2014 (79 FR 75800) for review until February 2, 2015. The Navy is the lead agency for the NWTT EIS/OEIS, and NMFS and the U.S. Coast Guard are cooperating agencies pursuant to 40 CFR 1501.6 and 1508.5. The January 2014 NWTT DEIS/OEIS and the December 2014 Supplement, which contain a list of the references used in this document, may be viewed at: http://www.nwtteis.com. Documents cited in this notice may also be viewed, by appointment, during regular business hours, at the aforementioned address.

Background

nt, may be viewed at: http://www.nwtteis.com. Documents cited in this notice may also be viewed, by appointment, during regular business hours, at the aforementioned address.

Background

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

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.”

The National Defense Authorization Act of 2004 (NDAA) (Public Law 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, migratio

ctivity” 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

NWTT Proposed Rule

On December 18, 2013, NMFS received an application from the Navy requesting two LOAs for the take of 26 species of marine mammals incidental to Navy training and testing activities to be conducted in the NWTT Study Area over 5 years. On September 26, 2014, the Navy submitted a revised LOA application to reflect updates to exposure estimates based on emergent

The Navy is requesting separate 5-year LOAs for training and testing activities to be conducted from 2015 through 2020. The Study Area includes the existing Northwest Training Range Complex, the Keyport Range Complex, Carr Inlet Operations Area, Southeast Alaska Acoustic Measurement Facility (SEAFAC), and Navy pierside locations where sonar maintenance or testing may occur (see Figure 1-1 of the LOA application for a map of the NWTT Study Area). The activities conducted within the NWTT Study Area are classified as military readiness activities. The Navy states that these activities may expose some of the marine mammals present within the NWTT Study Area to sound from underwater acoustic sources and explosives. The Navy is requesting authorization to take 26 marine mammal species by Level B (behavioral) harassment; 4 of those marine mammal species may be taken by injury (Level A harassment).

The LOA application and the January 2014 NWTT DEIS/OEIS contain proposed acoustic thresholds that were used to evaluate the Navy's AFTT and HSTT activities

to sound from underwater acoustic sources and explosives. The Navy is requesting authorization to take 26 marine mammal species by Level B (behavioral) harassment; 4 of those marine mammal species may be taken by injury (Level A harassment).

The LOA application and the January 2014 NWTT DEIS/OEIS contain proposed acoustic thresholds that were used to evaluate the Navy's AFTT and HSTT activities. The thresholds are based on evaluation of recent scientific studies; a detailed explanation of how they were derived is provided in the Criteria and Thresholds for Navy Acoustic Effects Analysis Technical Report (Finneran and Jenkins, 2012). NMFS is currently updating and revising all of its acoustic thresholds. Until that process is complete, NMFS will continue its long-standing practice of considering specific modifications to the acoustic thresholds currently employed for incidental take authorizations only after providing the public with an opportunity for review and comment. NMFS is requesting comments on all aspects of the proposed rule.

Modifications to HSTT, AFTT, MITT, and GOA Final Rules

The Navy is also requesting that NMFS authorize modifications to watchstander requirements, unrelated to implementation of mitigation measures, for observed behavior of marine mammals during MTEs in the HSTT, AFTT, MITT, and GOA study areas. With these proposed modifications the Navy would no longer be required to report individual marine mammal sighting information during MTEs when mitigation is not occurring in the study area. After 5 years of collecting marine mammal sighting data for all animals sighted during MTEs, NMFS and Navy have determined that without the ability to obtain species information this data set does not provide for any meaningful analysis beyond that which may be possible using mitigation-related observations alone. The Navy and NMFS have thoroughly investigated several potential uses for the data prior to reaching this conclusion

ne mammal sighting data for all animals sighted during MTEs, NMFS and Navy have determined that without the ability to obtain species information this data set does not provide for any meaningful analysis beyond that which may be possible using mitigation-related observations alone. The Navy and NMFS have thoroughly investigated several potential uses for the data prior to reaching this conclusion. Additionally, this reporting requirement places an undue administrative burden on ships watch teams. The Navy will continue to collect marine mammal sighting data during MTEs for every instance when any form of mitigation is employed such as powering down or securing sonar, maneuvering the ship, or delaying an event—in other words, in instances where animals are closer to the sound source around which mitigation measures are implemented. This data is useful in supporting mitigation effectiveness analyses and also may be helpful in supporting an understanding of the frequency with which marine mammals (generally, not by species) may be encountered or detected in close proximity to a particular source ( e.g., where the likelihood of auditory or other injury is higher). Additionally, the Navy will continue to implement their separate Integrated Comprehensive Monitoring Program, which includes studies that are specifically designed to contribute to our understanding of the animals affected and how Navy training and testing impacts them.

These modifications would be implemented through the revision of regulatory text for existing regulations governing the taking of marine mammals incidental to testing and/or training activities in HSTT, AFTT, MITT, and GOA study areas. Proposed revisions to the regulatory text are provided in the regulatory text at the end of this proposed rule. Proposed revisions to MITT regulatory text will be made in the MITT final rule, which is currently being prepared concurrent with the NWTT proposed rule and is expected to publish in the Federal Register prior to the NWTT final rule

ng activities in HSTT, AFTT, MITT, and GOA study areas. Proposed revisions to the regulatory text are provided in the regulatory text at the end of this proposed rule. Proposed revisions to MITT regulatory text will be made in the MITT final rule, which is currently being prepared concurrent with the NWTT proposed rule and is expected to publish in the Federal Register prior to the NWTT final rule. There are no MTEs or marine mammal sighting reporting requirements associated with Navy training and testing activities in the NWTT study area.

Background of Request

The Navy's mission is to maintain, train, and equip combat-ready naval forces capable of winning wars, deterring aggression, and maintaining freedom of the seas. Section 5062 of Title 10 of the United States Code directs the Chief of Naval Operations to train all military forces for combat. The Chief of Naval Operations meets that direction, in part, by conducting at-sea training exercises and ensuring naval forces have access to ranges, operating areas (OPAREAs) and airspace where they can develop and maintain skills for wartime missions and conduct research, development, testing, and evaluation (RDT&E) of naval systems.

The Navy proposes to continue conducting training and testing activities within the NWTT Study Area, which have been ongoing for decades with some activities dating back to at least the early 1900s. 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 war fighting doctrine and procedures, and force structure (organization of ships, submarines, aircraft, weapons, and personnel) changes. Such developments influence the frequency, duration, intensity, and location of required training and testing activities

d testing activities have fluctuated because of the introduction of new technologies, the evolving nature of international events, advances in war fighting doctrine and procedures, and force structure (organization of ships, submarines, aircraft, weapons, and personnel) changes. Such developments influence the frequency, duration, intensity, and location of required training and testing activities. The Navy analyzed many training and testing activities in the Study Area in the Tactical Training Theater Assessment and Planning Program Phase I and earlier documents, specifically the following environmental planning documents: Northwest Training Range Complex Final EIS/OEIS (U.S. Department of the Navy, 2010a), NAVSEA NUWC Keyport Range Complex Extension Final EIS/OEIS (U.S. Department of the Navy, 2010b), and the Final EIS for the Southeast Alaska Acoustic Measurement Facility (SEAFAC) (U.S. Department of the Navy, 1988). The Navy's LOA request covers training and testing activities that would occur for a 5-year period following the expiration of the first of the two current MMPA authorizations

The Navy's LOA application differs from the January 2014 NWTT DEIS/OEIS in that it contains updated information on the Washington Inland Waters stocks of harbor seals (Carretta et al., 2014) and their abundance in Hood Canal based on a new application of London et al. (2012). The January 2014 NWTT DEIS/OEIS analysis relied on NMFS' Stock Assessment Reports (SARs) through 2013 (Carretta et al., 2014), which did not incorporate the London et al. findings. London et al. (2012) reported the variability of harbor seal haulout behavior in a sub-portion of Hood Canal, covering 5 months of the year (July-November). The paper provided a range of haulout probabilities in Hood Canal that differed from the single value (65 percent—Huber et al., 2001) previously used by NMFS and Navy to calculate harbor seal abundance

t incorporate the London et al. findings. London et al. (2012) reported the variability of harbor seal haulout behavior in a sub-portion of Hood Canal, covering 5 months of the year (July-November). The paper provided a range of haulout probabilities in Hood Canal that differed from the single value (65 percent—Huber et al., 2001) previously used by NMFS and Navy to calculate harbor seal abundance. Recently, in discussions between the Navy and NMFS it was determined that it is now appropriate to incorporate London et al. (2012) for the Hood Canal stock only. This resulted in increasing the population estimate of the Hood Canal stock of harbor seals by a factor of approximately 3.26, resulting in a new abundance estimate of 3,555. In addition, in calculating its exposure estimates, the Navy also applied the haulout probability of 20 percent derived from London et al. (2012) which changed the percentage of harbor seals in the water from 35 percent (Huber et al., 2001) to 80 percent. These changes in assumptions result in a corresponding increase in estimated exposures because the Navy is assuming that there are more harbor seals present in Hood Canal and more of the animals will be in the water at any given time compared to the analysis presented in the January 2014 NWTT DEIS/OEIS. The result of these changes in the best available science is that the Navy has estimated additional Level A and Level B takes for training and testing activities per year. These changes to the estimates presented in the January 2014 NWTT DEIS/OEIS do not reflect a change in the Navy's proposed action nor a significant change to Navy's methodology. The vast majority of the increased exposure estimates are Level B harassment exposures that derive from the Navy's already conservative acoustic effects model

and Level B takes for training and testing activities per year. These changes to the estimates presented in the January 2014 NWTT DEIS/OEIS do not reflect a change in the Navy's proposed action nor a significant change to Navy's methodology. The vast majority of the increased exposure estimates are Level B harassment exposures that derive from the Navy's already conservative acoustic effects model. The Navy has determined that these Level A and Level B harassment exposures are not biologically significant to the population because (1) none of the estimated exposures result in mortality; (2) the monitoring and mitigations employed would likely reduce the severity of Level A exposures; (3) there are no indications that the historically occurring activities resulting in these behavioral harassment exposures are having any effect on this population's survival by altering behavior patterns such as breeding, nursing, feeding, or sheltering; (4) the population has been stable and likely at carrying capacity (Jeffries et al., 2003); (5) the population continues to use known large haulouts in Hood Canal and Dabob Bay that are adjacent to Navy testing and training activities; (6) the population continues to use known haulouts for pupping; and (7) the population continues to use the waters in and around Dabob Bay and Hood Canal. As such, the Navy has determined, and NMFS concurs, that it is not necessary to supplement the January 2014 NWTT DEIS/OEIS analysis as this information is not new significant information to the environmental impacts. However, the Navy has advised NMFS that all comments received on the proposed rule that address the changes in take estimates for the Hood Canal stock of harbor seals will be addressed by the Navy in its Final EIS/OEIS for NWTT.

Description of the Specified Activity

The Navy is requesting authorization to take marine mammals incidental to conducting training and testing activities

tal impacts. However, the Navy has advised NMFS that all comments received on the proposed rule that address the changes in take estimates for the Hood Canal stock of harbor seals will be addressed by the Navy in its Final EIS/OEIS for NWTT.

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 sonar use and underwater detonations are the stressors 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 January 2014 NWTT DEIS/OEIS and in the LOA application ( http://www.nmfs.noaa.gov/pr/permits/incidental/military.htm ) and are summarized here.

Overview of Training Activities

The Navy routinely trains in the NWTT Study Area in preparation for national defense missions. Training activities and exercises covered in the Navy's LOA request are briefly described below, and in more detail within Chapter 2 of the January 2014 NWTT DEIS/OEIS. Training activities are categorized into eight functional warfare areas (anti-air warfare; amphibious warfare; strike warfare; anti-surface warfare; anti-submarine warfare; electronic warfare; mine warfare; and naval special warfare). The Navy determined that the following stressors used in these warfare areas are most likely to result in impacts on marine mammals:

• Anti-surface warfare (impulsive sources [underwater detonations]) • Anti-submarine warfare (non-impulsive sources [active sonar], impulsive underwater detonations) • Mine warfare (non-impulsive sources, impulsive underwater detonations) The Navy's activities in anti-air warfare, electronic warfare, and naval special warfare do not involve stressors that could result in harassment of marine mammals. Therefore, these activities are not discussed further. The analysis and rationale for excluding these warfare areas is contained in the January 2014 DEIS/OEIS

ns) • Mine warfare (non-impulsive sources, impulsive underwater detonations) The Navy's activities in anti-air warfare, electronic warfare, and naval special warfare do not involve stressors that could result in harassment of marine mammals. Therefore, these activities are not discussed further. The analysis and rationale for excluding these warfare areas is contained in the January 2014 DEIS/OEIS.

Anti-Surface Warfare

The mission of anti-surface warfare (ASUW) is to defend against enemy ships or boats. When conducting anti-surface warfare, aircraft use cannons, air-launched cruise missiles, or other precision-guided munitions; ships use torpedoes, naval guns, and surface-to-surface missiles; and submarines use torpedoes or submarine-launched, anti-ship cruise missiles. Anti-surface warfare training includes surface-to-surface gunnery and missile exercises, air-to-surface gunnery and missile exercises, and submarine missile or exercise torpedo launch events.

Anti-Submarine Warfare

The mission of anti-submarine warfare (ASW) is to locate, neutralize, and defeat hostile submarine threats to surface forces. Anti-submarine warfare is based on the principle of a layered defense of surveillance and attack aircraft, ships, and submarines all searching for hostile submarines. These forces operate together or independently to gain early warning and detection, and to localize, track, target, and attack hostile submarine threats. Anti-submarine warfare training addresses basic skills such as detection and

Mine Warfare

The mission of mine warfare is to detect, and avoid or neutralize mines to protect Navy ships and submarines and to maintain free access to ports and shipping lanes. Mine warfare also includes offensive mine laying to gain control or deny the enemy access to sea space. Naval mines can be laid by ships, submarines, or aircraft. Mine warfare training includes exercises in which ships, aircraft, submarines, underwater vehicles, or marine mammal detection systems search for mines

ct Navy ships and submarines and to maintain free access to ports and shipping lanes. Mine warfare also includes offensive mine laying to gain control or deny the enemy access to sea space. Naval mines can be laid by ships, submarines, or aircraft. Mine warfare training includes exercises in which ships, aircraft, submarines, underwater vehicles, or marine mammal detection systems search for mines. Certain personnel train to destroy or disable mines by attaching and detonating underwater explosives to simulated mines. Other neutralization techniques involve impacting the mine with a bullet-like projectile or intentionally triggering the mine to detonate.

Other Activities

Other activities include pierside and at-sea maintenance of submarine and surface ship sonar systems.

Overview of Testing Activities

Testing activities covered in the Navy's LOA request are briefly described below, and in more detail within Chapter 2 of the January 2014 NWTT DEIS/OEIS. The Navy researches, develops, tests, and evaluates new platforms, systems and technologies. Many tests are conducted in realistic conditions at sea, and can range in scale from testing new software to operating portable devices to conducting tests of live weapons (such as the Service Weapon Test of a torpedo) to ensure they function as intended. Testing activities may occur independently of or in conjunction with training activities.

Many testing activities are conducted similarly to Navy training activities and are also categorized under one of the primary mission areas described above. Other testing activities are unique and are described within their specific testing categories. Because each test is conducted by a specific component of the Navy's research and acquisition community, which includes the Navy's Systems Commands and the Navy's scientific research organizations, the testing activities described in the LOA application are organized first by that particular organization as described below and in the order as presented

bed within their specific testing categories. Because each test is conducted by a specific component of the Navy's research and acquisition community, which includes the Navy's Systems Commands and the Navy's scientific research organizations, the testing activities described in the LOA application are organized first by that particular organization as described below and in the order as presented.

The Navy describes and analyzes the effects of its testing activities within the 2014 NWTT DEIS/OEIS. In its assessment, the Navy concluded that acoustic stressors from the use of underwater acoustic sources and underwater detonations resulted in impacts on marine mammals that rose to the level of harassment as defined under the MMPA. Therefore, the LOA application for NWTT provides the Navy's assessment of potential effects from these stressors in terms of the various activities in which they would be used.

The individual commands within the research and acquisition community included in the NWTT DEIS/OEIS and in the LOA application are:

• Naval Sea Systems Command (NAVSEA). Within NAVSEA are the following field activities:

○ Naval Undersea Warfare Center (NUWC) Division, Keyport ○ Naval Surface Warfare Center, Carderock Division (NSWCCD), Detachment Puget Sound ○ NSWCCD Southeast Alaska Acoustic Measurement Facility (SEAFAC) ○ Puget Sound Naval Shipyard and Intermediate Maintenance Facility ○ Various NAVSEA program offices • Naval Air Systems Command (NAVAIR)

Naval Sea Systems Command Testing Events

NAVSEA is responsible for engineering, building, buying, and maintaining the Navy's ships and submarines and associated combat systems. NAVSEA is broken up into two types of warfare centers: NUWC and the Naval Surface Warfare Center (NSWC).

NUWC provides Fleet readiness support for submarines, surface ships, torpedoes, mines, land attack systems, and Fleet training systems

mmand Testing Events

NUWC provides Fleet readiness support for submarines, surface ships, torpedoes, mines, land attack systems, and Fleet training systems. NAVSEA has several field activities operating out of Naval Base (NAVBASE) Kitsap, including NUWC Division Keyport, NSWCCD Detachment Puget Sound, and Puget Sound Naval Shipyard and Intermediate Maintenance Facility. NSWCCD Detachment Puget Sound also operates the SEAFAC facility in Alaska.

Each major category of NAVSEA activities in the Study Area is represented below. NUWC Division, Keyport and NSWCCD Detachment Puget Sound activities are grouped together in the discussion below to simplify review due to the diversity of activity types and locations they work in. Puget Sound Naval Shipyard and Intermediate Facility activities are grouped with the general activities conducted by NAVSEA. Numerous test activities and technical evaluations, in support of NAVSEA's systems development mission, often occur in conjunction with fleet activities within the Study Area.

Naval Undersea Warfare Center Division, Keyport Testing Activities

NUWC Division Keyport's mission is to provide test and evaluation services and expertise to support the Navy's evolving manned and unmanned vehicle program activities. NUWC Keyport has historically provided facilities and capabilities to support testing of torpedoes, other unmanned vehicles, submarine readiness, diver training, and similar activities that are critical to the success of undersea warfare. Range support requirements for such activities include testing, training, and evaluation of system capabilities such as guidance, control, and sensor accuracy in multiple marine environments ( e.g

ded facilities and capabilities to support testing of torpedoes, other unmanned vehicles, submarine readiness, diver training, and similar activities that are critical to the success of undersea warfare. Range support requirements for such activities include testing, training, and evaluation of system capabilities such as guidance, control, and sensor accuracy in multiple marine environments ( e.g. , differing depths, salinity levels, sea states) and in surrogate and simulated war-fighting environments. Technological advancements in the materials, instrumentation, guidance systems, and tactical capabilities of manned and unmanned vehicles continue to evolve in parallel with emerging national security priorities and threat assessments. However, NUWC Keyport does not utilize explosives in any testing scenarios.

Naval Surface Warfare Center, Carderock Division

NSWCCD includes two organizations that conduct testing activities: NSWCCD, Detachment Puget Sound and NSWCCD SEAFAC. Detachment Puget Sound testing activities are aligned with its mission to provide research, development, test, and evaluation (RDT&E), analysis, acquisition support, in-service engineering, logistics and integration of surface and undersea vehicles and associated systems; develop and apply science and technology associated with naval architecture and marine engineering; and provide support to the maritime industry. Activities and support include engineering, technical, operations, diving, and logistics required for the RDT&E associated with:

eering, technical, operations, diving, and logistics required for the RDT&E associated with:

• Advanced Technology Concepts, Engineering and Proofing • Experimental Underwater Vehicles, Systems, Subsystems and Components • Specialized Underwater Systems, Equipment, Tools and Hardware • Acoustic Data Acquisition, Analysis and Measurement Systems (required to measure U.S. Navy Acoustic Signatures). These activities can be broken down into four major testing categories to include: System, Subsystem and Component Acoustic Testing Pierside; Performance Testing at Sea; Development Testing and Training; and Proof of Concept Testing.

NSWCCD SEAFAC makes high fidelity directive volumetric and line arrays passive acoustic signature measurements. The SEAFAC site includes directive line arrays and data collection and processing systems for real-time data analysis and signature evaluation.

SEAFAC provides the capability to perform RDT&E analyses to determine the sources of radiated acoustic noise, to assess vulnerability, and to develop quieting measures. Unforeseen emergent Navy requirements may influence actual testing activities during the time period under consideration. Testing activities that would occur at SEAFAC are identified to the extent practicable throughout this application.

Naval Sea Systems Command Program Office Sponsored Testing Activities

NAVSEA also conducts tests that are not associated with NUWC Keyport or NSWCCD. Activities are conducted at Navy piers at NAVBASE Kitsap, Bremerton; NAVBASE Kitsap, Bangor; and Naval Station Everett; and in conjunction with fleet activities off the coast of Washington, Oregon, and northern California. Tests within this category include, but are not limited to, Life Cycle Activities, Shipboard Protection Systems and Swimmer Defense Testing, Unmanned Vehicle Testing, ASUW/ASW Testing, and New Ship Construction.

Naval Air Systems Command Testing Events

NAVAIR testing events generally fall into the primary mission areas used by the fleets

he coast of Washington, Oregon, and northern California. Tests within this category include, but are not limited to, Life Cycle Activities, Shipboard Protection Systems and Swimmer Defense Testing, Unmanned Vehicle Testing, ASUW/ASW Testing, and New Ship Construction.

Naval Air Systems Command Testing Events

NAVAIR testing events generally fall into the primary mission areas used by the fleets. NAVAIR events include, but are not limited to, the testing of new aircraft platforms, weapons, and systems before those platforms, weapons and systems are integrated into the fleet. In this application, NAVAIR testing activities are limited to ASW testing of sonobuoys. The sonobuoys tested include both passive and active non-impulsive, sonobuoys using impulsive sources, and high duty cycle sonobuoys.

Description of Sonar, Ordnance, Targets, and Other Systems

The Navy uses a variety of sensors, platforms, weapons, and other devices to meet its mission. Training and testing with these systems may introduce acoustic (sound) energy into the environment. This section describes and organizes sonar systems, ordnance, munitions, targets, and other systems to facilitate understanding of the activities in which these systems are used. Underwater sound is described as one of two types for the purposes of the LOA application: impulsive and non-impulsive. Underwater detonations of explosives and other percussive events are impulsive sounds. Sonar and similar sound producing systems are categorized as non-impulsive sound sources.

Sonar and Other Active Acoustic Sources

Modern sonar technology includes a variety of sonar sensor and processing systems. The simplest active sonar emits sound waves, or “pings,” sent out in multiple directions and the sound waves then reflect off of the target object in multiple directions. The sonar source calculates the time it takes for the reflected sound waves to return; this calculation determines the distance to the target object

dern sonar technology includes a variety of sonar sensor and processing systems. The simplest active sonar emits sound waves, or “pings,” sent out in multiple directions and the sound waves then reflect off of the target object in multiple directions. The sonar source calculates the time it takes for the reflected sound waves to return; this calculation determines the distance to the target object. More sophisticated active sonar systems emit a ping and then rapidly scan or listen to the sound waves in a specific area. This provides both distance to the target and directional information. Even more advanced sonar systems use multiple receivers to listen to echoes from several directions simultaneously and provide efficient detection of both direction and distance. The Navy rarely uses active sonar continuously throughout activities. When sonar is in use, the pings occur at intervals, referred to as a duty cycle, and the signals themselves are very short in duration. For example, sonar that emits a 1-second ping every 10 seconds has a 10-percent duty cycle. The Navy utilizes sonar systems and other acoustic sensors in support of a variety of mission requirements. Primary uses include the detection of and defense against submarines (anti-submarine warfare) and mines (mine warfare); safe navigation and effective communications; use of unmanned undersea vehicles; and oceanographic surveys. Sources of sonar and other active acoustic sources include surface ship sonar, sonobuoys, torpedoes, range pingers, and unmanned underwater vehicles.

Ordnance and Munitions

ed underwater vehicles.

Ordnance and Munitions

Most ordnance and munitions used during training and testing events fall into three basic categories: projectiles (such as gun rounds), missiles (including rockets), and bombs. Ordnance can be further defined by their net explosive weight, which considers the type and quantity of the explosive substance without the packaging, casings, bullets, etc. Net explosive weight (NEW) is the trinitrotoluene (TNT) equivalent of energetic material, which is the standard measure of strength of bombs and other explosives. For example, a 12.7-centimeter (cm) shell fired from a Navy gun is analyzed at about 9.5 pounds (lb) (4.3 kilograms (kg)) of NEW. The Navy also uses non-explosive ordnance in place of high explosive ordnance in many training and testing events. Non-explosive ordnance munitions look and perform similarly to high explosive ordnance, but lack the main explosive charge.

Defense Countermeasures

Naval forces depend on effective defensive countermeasures to protect themselves against missile and torpedo attack. Defensive countermeasures are devices designed to confuse, distract, and confound precision guided munitions. Defensive countermeasures analyzed in the LOA application include acoustic countermeasures, which are used by surface ships and submarines to defend against torpedo attack. Acoustic countermeasures are either released from ships and submarines, or towed at a distance behind the ship.

Mine Warfare Systems

The Navy divides mine warfare systems into two categories: Mine detection and mine neutralization. Mine detection systems are used to locate, classify, and map suspected mines, on the surface, in the water column, or on the sea floor. The Navy analyzed the following mine detection systems for potential impacts to marine mammals:

• Towed or hull-mounted mine detection systems. These detection systems use acoustic and laser or video sensors to locate and classify suspect mines

e neutralization. Mine detection systems are used to locate, classify, and map suspected mines, on the surface, in the water column, or on the sea floor. The Navy analyzed the following mine detection systems for potential impacts to marine mammals:

• Towed or hull-mounted mine detection systems. These detection systems use acoustic and laser or video sensors to locate and classify suspect mines. Fixed and rotary wing platforms, ships, and unmanned vehicles are used for towed systems, which can rapidly assess large areas.

• Airborne Laser Mine Detection Systems. Airborne laser detection systems work in concert with neutralization systems. The detection system initially locates mines and a neutralization system is then used to relocate and neutralize the mine.

• Unmanned/remotely operated vehicles. These vehicles use acoustic and video or lasers to locate and classify mines and provide unique capabilities in nearshore littoral areas, surf zones, ports, and channels.

Mine neutralization systems disrupt, disable, or detonate mines to clear ports and shipping lanes, as well as littoral, surf, and beach areas in support of naval amphibious operations. Mine neutralization systems can clear individual mines or a large number of mines quickly. The Navy analyzed the following mine neutralization systems for potential impacts to marine mammals:

• Towed influence mine sweep systems. These systems use towed equipment that mimic a particular ship's magnetic and acoustic signature triggering the mine and causing it to explode.

• Towed mechanical mine sweeping systems.These systems tow a sweep wire to snag the line that attaches a moored mine to its anchor and then uses a series of cables and cutters to sever those lines. Once these lines are cut, the mines float to the surface where Navy personnel can neutralize the mines.

• Unmanned/remotely operated mine neutralization systems. Surface ships and helicopters operate these systems, which place explosive charges near or directly against mines to destroy the mine

ttaches a moored mine to its anchor and then uses a series of cables and cutters to sever those lines. Once these lines are cut, the mines float to the surface where Navy personnel can neutralize the mines.

• Unmanned/remotely operated mine neutralization systems. Surface ships and helicopters operate these systems, which place explosive charges near or directly against mines to destroy the mine.

• Projectiles. Small- and medium-caliber projectiles, fired from surface ships or hovering helicopters, are used to neutralize floating and near-surface mines.

• Diver emplaced explosive charges. Operating from small craft, divers put explosive charges near or on mines to destroy the mine or disrupt its ability to function.

Explosive charges are used during mine neutralization system training activities; however, only non-explosive mines or mine shapes would be used.

Classification of Non-Impulsive and Impulsive Sources Analyzed

In order to better organize and facilitate the analysis of about 300 sources of underwater non-impulsive sound or impulsive energy, the Navy developed a series of source classifications, or source bins. This method of analysis provides the following benefits:

• Allows for new sources to be covered under existing authorizations, as long as those sources fall within the parameters of a “bin;”

• Simplifies the data collection and reporting requirements anticipated under the MMPA;

• Ensures a conservative approach to all impact analysis because all sources in a single bin are modeled as the loudest source ( e.g. , lowest frequency, highest source level, longest duty cycle, or largest net explosive weight within that bin);

• Allows analysis to be conducted more efficiently, without compromising the results;

l, longest duty cycle, or largest net explosive weight within that bin);

• Allows analysis to be conducted more efficiently, without compromising the results;

• Provides a framework to support the reallocation of source usage (hours/explosives) between different source bins, as long as the total number and severity of marine mammal 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.

A description of each source classification is provided in Tables 1-3. Non-impulsive sources are grouped into bins based on the frequency, source level when warranted, and how the source would be used. Impulsive bins are based on the net explosive weight of the munitions or explosive devices. The following factors further describe how non-impulsive sources are divided:

• Frequency of the non-impulsive source:

○ Low-frequency sources operate below 1 kilohertz (kHz) ○ Mid-frequency sources operate at or 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 • Source level of the non-impulsive source:

○ Greater than 160 decibels (dB), but less than 180 dB ○ Equal to 180 dB and up to 200 dB ○ Greater than 200 dB How a sensor is used determines how the sensor's acoustic emissions are analyzed. Factors to consider include pulse length (time source is on); beam pattern (whether sound is emitted as a narrow, focused beam, or, as with most explosives, in all directions); and duty cycle (how often a transmission occurs in a given time period during an event).

There are also non-impulsive sources with characteristics that are not anticipated to result in takes of marine mammals

re analyzed. Factors to consider include pulse length (time source is on); beam pattern (whether sound is emitted as a narrow, focused beam, or, as with most explosives, in all directions); and duty cycle (how often a transmission occurs in a given time period during an event).

There are also non-impulsive sources with characteristics that are not anticipated to result in takes of marine mammals. These sources have low source levels, narrow beam widths, downward directed transmission, short pulse lengths, frequencies beyond known hearing ranges of marine mammals, or some combination of these factors. These sources were not modeled by the Navy, but are qualitatively analyzed in Table 1-4 of the LOA application and in the January 2014 NWTT DEIS/OEIS. These sources generally meet the following criteria:

• Acoustic sources with frequencies greater than 200 kHz (based on known marine mammal hearing ranges) • Sources with source levels less than 160 dB Table 1—Impulsive Training and Testing Source Classes Analyzed Source class Representative munitions Net explosive weight (lbs) E1 Medium-caliber projectiles 0.1-0.25 (45.4-113.4 g). E3 Large-caliber projectiles >0.5-2.5 (>226.8 g-1.1 kg). E4 Improved Extended Echo Ranging Sonobuoy >2.5-5.0 (1.1-2.3 kg). E5 5 in. (12.7 cm) projectiles >5-10 (>2.3-4.5 kg). E8 250 lb. (113.4 kg) bomb >60-100 (>27.2-45.4 kg). E10 1,000 lb. (453.6 kg) bomb >250-500 (>113.4-226.8 kg). E11 650 lb. (294.8 kg) mine >500-650 (>226.8-294.8 kg). E12 2,000 lb. (907.2 kg) bomb >650-1,000 (>294.8-453.6 kg). Table 2—Non-Impulsive Training Source Classes Analyzed Source class category Source class Description Mid-Frequency (MF): Tactical and non-tactical sources that produce mid-frequency (1 to 10 kHz) signals MF1 Active hull-mounted surface ship sonar ( e.g. , AN/SQS-53C and AN/SQS-60). MF3 Active hull-mounted submarine sonar ( e.g. , AN/BQQ-10). MF4 Active helicopter-deployed dipping sonar ( e.g. , AN/AQS-22 and AN/AQS-13). MF5 Active acoustic sonobuoys ( e.g. , AN/SSQ-62 DICASS 2 )

class Description Mid-Frequency (MF): Tactical and non-tactical sources that produce mid-frequency (1 to 10 kHz) signals MF1 Active hull-mounted surface ship sonar ( e.g. , AN/SQS-53C and AN/SQS-60). MF3 Active hull-mounted submarine sonar ( e.g. , AN/BQQ-10). MF4 Active helicopter-deployed dipping sonar ( e.g. , AN/AQS-22 and AN/AQS-13). MF5 Active acoustic sonobuoys ( e.g. , AN/SSQ-62 DICASS 2 ). MF11 Hull-mounted surface ship sonar with an active duty cycle greater than 80%. High-Frequency (HF) and Very High-Frequency (VHF): Tactical and non-tactical sources that produce high-frequency (greater than 10 kHz but less than 200 kHz) signals HF1 HF4 Active hull-mounted submarine sonar ( e.g. , AN/BQQ-15). Active mine detection, classification, and neutralization sonar ( e.g. , AN/SQS-20). HF6 Active sources (equal to 180 dB and up to 200 dB). Anti-Submarine Warfare (ASW): Tactical sources such as active sonobuoys and acoustic countermeasures systems used during ASW training activities ASW2 ASW3 MF active Multistatic Active Coherent (MAC) sonobuoy ( e.g. , AN/SSQ-125). MF active towed active acoustic countermeasure systems ( e.g. , AN/SLQ-25 NIXIE). Table 3—Non-Impulsive Testing Source Classes Analyzed Source class category Source class Description Low-Frequency (LF): Sources that produce low-frequency (less than 1 kilohertz [kHz]) signals LF4 LF5 Low-frequency sources equal to 180 dB and up to 200 dB. Low-frequency sources less than 180 dB. Mid-Frequency (MF): Tactical and non-tactical sources that produce mid-frequency (1 to 10 kHz) signals MF3 MF4 Hull-mounted submarine sonar ( e.g. , AN/BQQ-10). Helicopter-deployed dipping sonar ( e.g. , AN/AQS-22 and AN/AQS-13). MF5 Active acoustic sonobuoys ( e.g. , DICASS). MF6 Active underwater sound signal devices ( e.g. , MK-84). MF8 Active sources (greater than 200 dB). MF9 Active sources (equal to 180 dB and up to 200 dB). MF10 Active sources (greater than 160 dB, but less than 180 dB) not otherwise binned

nted submarine sonar ( e.g. , AN/BQQ-10). Helicopter-deployed dipping sonar ( e.g. , AN/AQS-22 and AN/AQS-13). MF5 Active acoustic sonobuoys ( e.g. , DICASS). MF6 Active underwater sound signal devices ( e.g. , MK-84). MF8 Active sources (greater than 200 dB). MF9 Active sources (equal to 180 dB and up to 200 dB). MF10 Active sources (greater than 160 dB, but less than 180 dB) not otherwise binned. MF11 Hull-mounted surface ship sonar with an active duty cycle greater than 80%. MF12 High duty cycle—variable depth sonar. High-Frequency (HF) and Very High-Frequency (VHF): Tactical and non-tactical sources that produce high-frequency (greater than 10 kHz but less than 200 kHz) signals HF1 HF3 HF5 1 Hull-mounted submarine sonar ( e.g. , AN/BQQ-10). Hull-mounted submarine sonar (classified). Active sources (greater than 200 dB). HF6 Active sources (equal to 180 dB and up to 200 dB). VHF2 Active sources with a frequency greater than 100 kHz, up to 200 kHz with a source level less than 200 dB. Anti-Submarine Warfare (ASW): Tactical sources such as active sonobuoys and acoustic countermeasures systems used during the conduct of ASW testing activities ASW1 ASW2 Mid-frequency Deep Water Active Distributed System (DWADS). Mid-frequency Multistatic Active Coherent sonobuoy ( e.g. , AN/SSQ-125)—sources analyzed by number of items (sonobuoys). ASW2 Mid-frequency sonobuoy ( e.g. , high duty cycle)—Sources that are analyzed by hours. ASW3 Mid-frequency towed active acoustic countermeasure systems ( e.g. , AN/SLQ-25). ASW4 Mid-frequency expendable active acoustic device countermeasures ( e.g. , MK-3). Torpedoes (TORP): Source classes associated with the active acoustic signals produced by torpedoes TORP1 TORP2 Lightweight torpedo ( e.g. , MK-46, MK-54). Heavyweight torpedo ( e.g. , MK-48, electric vehicles). Acoustic Modems (M): Systems used to transmit data acoustically through water M3 Mid-frequency acoustic modems (greater than 190 dB) ( e.g. , Underwater Emergency Warning System, Aid to Navigation)

s (TORP): Source classes associated with the active acoustic signals produced by torpedoes TORP1 TORP2 Lightweight torpedo ( e.g. , MK-46, MK-54). Heavyweight torpedo ( e.g. , MK-48, electric vehicles). Acoustic Modems (M): Systems used to transmit data acoustically through water M3 Mid-frequency acoustic modems (greater than 190 dB) ( e.g. , Underwater Emergency Warning System, Aid to Navigation). Swimmer Detection Sonar (SD): Systems used to detect divers and submerged swimmers SD1 High-frequency sources with short pulse lengths, used for the detection of swimmers and other objects for the purpose of port security. Synthetic Aperture Sonar (SAS): Sonar in which active acoustic signals are post-processed to form high-resolution images of the seafloor SAS2 High frequency unmanned underwater vehicle (UUV) ( e.g. , UUV payloads). Notes : 1 For this analysis, HF5 consists of only one source; the modeling was conducted specifically for that source. 2 DICASS = Directional Command Activated Sonobuoy System Proposed Action. Training and Testing

The training and testing activities that the Navy proposes to conduct in the NWTT Study Area are listed in Tables 4-6. Detailed information about each proposed activity (stressor, training or testing event, description, sound source, duration, and geographic location) can be found in the LOA application and in Appendix A of the January 2014 NWTT DEIS/OEIS. NMFS used the detailed information in the LOA application and in Appendix A of the January 2014 NWTT DEIS/OEIS to analyze the potential impacts from training and testing activities on marine mammals. The Navy's proposed activities are anticipated to meet training and testing needs in the years 2015-2020.

Summary of Impulsive and Non-Impulsive Sources

Table 4 provides a quantitative annual summary of training activities by sonar and other active acoustic source class analyzed in the Navy's LOA request

S to analyze the potential impacts from training and testing activities on marine mammals. The Navy's proposed activities are anticipated to meet training and testing needs in the years 2015-2020.

Summary of Impulsive and Non-Impulsive Sources

Table 4 provides a quantitative annual summary of training activities by sonar and other active acoustic source class analyzed in the Navy's LOA request.

Table 4—Annual Hours of Sonar and Other Active Acoustic Sources Used During Training Within the NWTT Study Area Source class category Source class Annual use Mid-Frequency (MF) Active sources from 1 to 10 kHz MF1 MF3 MF4 166 hours. 70 hours. 4 hours. MF5 896 items. MF11 16 hours. High-Frequency (HF) Tactical and non-tactical sources that produce signals greater than 10 kHz but less than 100 kHz HF1 HF4 HF6 48 hours. 384 hours. 192 hours. Anti-Submarine Warfare (ASW) ASW2 ASW3 720 items. 78 hours. Table 5 provides a quantitative annual summary of testing activities by sonar and other active sources analyzed in the Navy's LOA request.

Table 5—Annual Hours of Sonar and Other Active Acoustic Sources Used During Testing Within the NWTT Study Area Source class category Source class Annual use Low-Frequency (LF): Sources that produce signals less than 1 kHz LF4 LF5 110 hours. 71 hours. Mid-Frequency (MF): Tactical and non-tactical sources that produce signals from 1 to 10 kHz MF3 MF4 MF5 MF6 MF8 MF9 MF10 MF11 MF12 161 hours. 10 hours. 273 items. 12 items. 40 hours. 1,183 hours. 1,156 hours. 34 hours. 24 hours. High-Frequency (HF) and Very High-Frequency (VHF): Tactical and non-tactical sources that produce signals greater than 10 kHz but less than 200 kHz HF1 HF3 HF5 1 HF6 161 hours. 145 hours. 360 hours. 2,099 hours. Very High-Frequency (VHF): Tactical and non-tactical sources that produce signals greater than 100 kHz but less than 200 kHz VHF2 35 hours. Anti-Submarine Warfare (ASW): Tactical sources used during ASW training and testing activities ASW1 ASW2 2 ASW2 2 ASW3 ASW4 16 hours. 64 hours. 170 items. 444 hours

an 10 kHz but less than 200 kHz HF1 HF3 HF5 1 HF6 161 hours. 145 hours. 360 hours. 2,099 hours. Very High-Frequency (VHF): Tactical and non-tactical sources that produce signals greater than 100 kHz but less than 200 kHz VHF2 35 hours. Anti-Submarine Warfare (ASW): Tactical sources used during ASW training and testing activities ASW1 ASW2 2 ASW2 2 ASW3 ASW4 16 hours. 64 hours. 170 items. 444 hours. 1,182 hours. Torpedoes (TORP): Source classes associated with active acoustic signals produced by torpedoes TORP1 TORP2 315 items. 299 items. Acoustic Modems (M): Transmit data acoustically through the water M3 1,519 hours. Swimmer Detection Sonar (SD): Used to detect divers and submerged swimmers SD1 757 hours. Synthetic Aperture Sonar (SAS): Sonar in which active acoustic signals are post-processed to form high-resolution images of the seafloor SAS2 798 hours. 1 For this analysis, HF5 consists of only one source; the modeling was conducted specifically for that source. 2 The ASW2 bin contains sources that are analyzed by hours and some that are analyzed by count of items. There is no overlap of the numbers in the two rows. Table 6 provides a quantitative annual summary of training explosive source classes analyzed in the Navy's LOA request.

Table 6—Proposed Annual Number of Impulsive Source Detonations During Training in the NWTT Study Area Explosive class Net explosive weight (NEW) Annual in-water detonations (training) E1 (0.1 lb.-0.25 lb.) 48 E3 (>0.5 lb.-2.5 lb.) 6 E5 (>5 lb.-10 lb.) 80 E10 (>250 lb.-500 lb.) 4 E12 (>650 lb.-1000 lb.) 10 Table 7 provides a quantitative annual summary of testing explosive source classes analyzed in the Navy's LOA request

Number of Impulsive Source Detonations During Training in the NWTT Study Area Explosive class Net explosive weight (NEW) Annual in-water detonations (training) E1 (0.1 lb.-0.25 lb.) 48 E3 (>0.5 lb.-2.5 lb.) 6 E5 (>5 lb.-10 lb.) 80 E10 (>250 lb.-500 lb.) 4 E12 (>650 lb.-1000 lb.) 10 Table 7 provides a quantitative annual summary of testing explosive source classes analyzed in the Navy's LOA request.

Table 7—Proposed Annual Number of Impulsive Source Detonations During Testing in the NWTT Study Area Explosive class Net explosive weight (NEW) Annual In-Water Detonations (testing) E3 (>0.5 lb.-2.5 lb.) 72 E4 (>2.5 lb.-5 lb.) 70 E8 (>60 lb.-100 lb.) 3 E11 (>500 lb.-650 lb.) 3 Other Stressors—Vessel Strikes

In addition to potential impacts to marine mammals from activities using explosives or sonar and other active acoustic sources, the Navy also considered ship strike impacts to marine mammals. The Navy assessed that no additional stressors would result in a take and require authorization under the MMPA.

Vessel strikes may occur from surface operations and sub-surface operations (excluding bottom crawling, unmanned underwater vehicles). Vessels used as part of the Navy's proposed NWTT training and testing activities (proposed action) include ships, submarines and boats ranging in size from small, 16-foot (ft.) (5-meter [m]) rigid hull inflatable boats to aircraft carriers with lengths up to 1,092 ft. (333 m). Representative Navy vessel types, lengths, and speeds used in both training and testing activities are shown in Table 8

). Vessels used as part of the Navy's proposed NWTT training and testing activities (proposed action) include ships, submarines and boats ranging in size from small, 16-foot (ft.) (5-meter [m]) rigid hull inflatable boats to aircraft carriers with lengths up to 1,092 ft. (333 m). Representative Navy vessel types, lengths, and speeds used in both training and testing activities are shown in Table 8.

Table 8—Representative Navy Vessel Types, Lengths, and Speeds Used Within the NWTT Study Area Vessel type Example(s) Length Typical operating speed Max speed Aircraft Carrier Aircraft Carrier >900 ft (>300 m) 10-15 knots 30+ knots Surface Combatants Cruisers, Destroyers, Frigates, Littoral Combat Ships 330-660 ft (100-200 m) 10-15 knots 30+ knots Support Craft/Other Range Support Craft, Combat Rubber Raiding Craft, Landing Craft, Utility; Submarine Tenders, Yard Patrol Craft, Protection Vessels, Barge 16-250 ft (5-80 m) Variable 20 knots Support Craft/Other—Specialized High Speed Patrol Coastal Ships, Patrol Boats, Rigid Hull Inflatable Boat, High Speed Protection Vessels 33-130 ft (10-40 m) Variable 50+ knots Submarines Fleet Ballistic Missile Submarines, Attack Submarines, Guided Missile Submarines 330-660 ft (100-200 m) 8-13 knots 20+ knots Large Navy ships greater than 65 ft. (20 m) generally operate at speeds in the range of 10-15 knots for fuel conservation when cruising. Submarines generally operate at speeds in the range of 8-13 knots during transit and slower for certain tactical maneuvers. Small craft (for purposes of this discussion less than 65 ft. [20 m] in length) have much more variable speeds, dependent on the mission. While these speeds are representative, some vessels operate outside of these speeds due to unique training or safety requirements for a given event. Examples include increased speeds needed for flight operations, full speed runs to test engineering equipment, time critical positioning needs, etc

discussion less than 65 ft. [20 m] in length) have much more variable speeds, dependent on the mission. While these speeds are representative, some vessels operate outside of these speeds due to unique training or safety requirements for a given event. Examples include increased speeds needed for flight operations, full speed runs to test engineering equipment, time critical positioning needs, etc. Examples of decreased speeds include speeds less than 5 knots or completely stopped for launching small boats, certain tactical maneuvers, target launch or retrievals, etc.

The number of Navy vessels in the Study Area varies based on training and testing schedules. Most activities include either one or two vessels, with an average of one vessel per activity, and last from a few hours up to 2 weeks. Vessel movement and the use of in-water devices as part of the proposed action would be concentrated in certain

The Navy is analyzing the potential environmental impacts of approximately 226 ongoing annual Maritime Security Operations events in Puget Sound and the Strait of Juan de Fuca. These critical events have been occurring since 2006 and exercise the Navy's Transit Protection System, where up to nine escort vessels provide protection during all nuclear ballistic missile submarine (SSBN) transits between the vessel's homeport and the dive/surface point in the Strait of Juan de Fuca or Dabob Bay. During a Transit Protection System event, the security escorts enforce a moving 1,000 yard security zone around the SSBN to prevent other vessels from approaching while the SSBN is in transit on the surface. These events include security escort vessels, U.S. Coast Guard personnel and their ancillary equipment and weapons systems. The Transit Protection System involves the movement of security vessels and also includes periodic exercises and firearms training (with blank rounds)

000 yard security zone around the SSBN to prevent other vessels from approaching while the SSBN is in transit on the surface. These events include security escort vessels, U.S. Coast Guard personnel and their ancillary equipment and weapons systems. The Transit Protection System involves the movement of security vessels and also includes periodic exercises and firearms training (with blank rounds). Given the relative slow speed of the escorted and blocking vessels and multiple lookouts, no marine mammal vessel strikes are expected as a result of these events.

Navy policy (Chief of Naval Operations Instruction 3100.6H) requires Navy vessels to report all whale strikes. That information is collected by the Office of the Chief of Naval Operations Energy and Environmental Readiness Division (OPNAV N45) and cumulatively provided to NMFS on an annual basis. In addition, the Navy and NMFS also have standardized regional reporting protocols for communicating to regional NMFS stranding coordinators information on any Navy vessel strikes as soon as possible. These communication procedures will remain in place for the duration of the LOAs. There are no records of any Navy vessel strikes to marine mammals during training or testing activities in the NWTT Study Area.

Duration and Location

Training and testing activities would be conducted in the Study Area throughout the year from November 2015 through November 2020.

The Study Area is composed of established maritime operating and warning areas in the eastern North Pacific Ocean region, including areas of the Strait of Juan de Fuca, Puget Sound, and Western Behm Canal in southeastern Alaska. The Study Area includes air and water space within and outside Washington state waters, and outside state waters of Oregon and Northern California. The Study Area includes four existing range complexes and facilities: The Northwest Training Range Complex (NWTRC), the Keyport Range Complex, Carr Inlet Operations Area, and SEAFAC

n de Fuca, Puget Sound, and Western Behm Canal in southeastern Alaska. The Study Area includes air and water space within and outside Washington state waters, and outside state waters of Oregon and Northern California. The Study Area includes four existing range complexes and facilities: The Northwest Training Range Complex (NWTRC), the Keyport Range Complex, Carr Inlet Operations Area, and SEAFAC. In addition to these range complexes, the Study Area also includes Navy pierside locations where sonar maintenance and testing occurs as part of overhaul, modernization, maintenance and repair activities at NAVBASE Kitsap, Bremerton; NAVBASE Kitsap, Bangor; and Naval Station Everett.

A range complex is a designated set of specifically bounded geographic areas and encompasses a water component (above and below the surface), and may encompass airspace and a land component where training and testing of military platforms, tactics, munitions, explosives, and EW systems occurs. Range complexes include established OPAREAs, Restricted Areas, and special use airspace (SUA), which may be further divided to provide better control of the area and events for safety reasons. These designations are further described in Chapter 2 of the LOA application.

The Study Area includes only the at-sea components of the training and testing areas and facilities. The Navy is using “at-sea” to cover activity in, on, and over the water, but not activity on or over the land, which may include activities in the surf zone or supported from shore-side locations.

vity on or over the land, which may include activities in the surf zone or supported from shore-side locations.

Military activities in the Study Area occur (1) on the ocean surface, (2) beneath the ocean surface, and (3) in the air. To aid in the description of the ranges covered in the January 2014 NWTT DEIS/OEIS, the ranges are divided into three distinct geographic and functional subdivisions. All of the training and testing activities proposed in this application would occur in one or more of these three range subdivisions:

• The Offshore Area • The Inland Waters • Western Behm Canal, Alaska Offshore Area

The Offshore Area of the Study Area includes air, surface, and subsurface OPAREAs extending generally west from the coastline of Washington, Oregon, and Northern California for a distance of approximately 250 nm into international waters. The eastern boundary of the Offshore Area is 12 nm off the coastline for most of the Study Area, including southern Washington, Oregon, and Northern California. The Offshore Area includes the ocean all the way to the coastline only along the Washington coast beneath the airspace of W-237 and the Olympic Military Operations Area (MOA) and the Washington coastline north of the Olympic MOA. The components of the Offshore Area are described below.

Airspace

The SUA in the Offshore Area is comprised of Warning Area 237 (W-237), which extends westward off the coast of Northern Washington State and is divided into nine sub-areas (A-H, and J). The eastern boundary of W-237 lies 3 nm off the coast of Washington. The floor of W-237 extends to the ocean surface and the ceiling of the airspace varies between 27,000 ft. (8,200 m) in areas E, H, and J; 50,000 ft. (15,200 m) in areas A and B; and unlimited in areas C, D, F, and G, with a total area of 25,331 square nautical miles (nm 2 ).

The Olympic MOA overlays both land (the Olympic Peninsula) and sea (extending to 3 nm off the coast of Washington into the Pacific Ocean). The MOA lower limit is 6,000 ft

and the ceiling of the airspace varies between 27,000 ft. (8,200 m) in areas E, H, and J; 50,000 ft. (15,200 m) in areas A and B; and unlimited in areas C, D, F, and G, with a total area of 25,331 square nautical miles (nm 2 ).

The Olympic MOA overlays both land (the Olympic Peninsula) and sea (extending to 3 nm off the coast of Washington into the Pacific Ocean). The MOA lower limit is 6,000 ft. (1,800 m) above mean sea level but not below 1,200 ft. above ground level, and the upper limit is up to, but not including, 18,000 ft. (5,500 m), with a total area coverage of 1,614 nm 2 .

Above the Olympic MOA is the Olympic Air Traffic Controlled Assigned Airspace (ATCAA), which has a floor coinciding with the Olympic MOA ceiling. The ATCAA has an upper limit of 35,000 ft. (10,700 m).

For the LOA application, the Olympic MOA and the Olympic ATCAA Are components of the Offshore Area

Inland Waters

The Inland Waters includes air, sea, and undersea space inland of the coastline, from buoy “J” at 48° 29.6′ N, 125° W, eastward to include all waters of the Strait of Juan de Fuca and the Puget Sound. None of this area extends into Oregon or California. Within the Inland Waters are specific geographic components in which training and testing occur. The Inland Waters and its component areas are described below.

Airspace

Restricted Area 6701 (R-6701, Admiralty Bay) is a Restricted Area over Admiralty Bay, Washington with a lower limit at the ocean surface and an upper limit of 5,000 ft. This airspace covers a total area of 56 nm 2 .

Chinook A and B MOAs are 56 nm 2 of airspace south and west of Admiralty Bay. The Chinook MOAs extend from 300 ft. to 5,000 ft. above the ocean surface

described below.

Airspace

Chinook A and B MOAs are 56 nm 2 of airspace south and west of Admiralty Bay. The Chinook MOAs extend from 300 ft. to 5,000 ft. above the ocean surface.

Sea and Undersea Space

Explosive Ordnance Disposal Underwater Ranges —Two active EOD ranges are located in the Inland Waters at the following locations:

• Hood Canal EOD Training Range

• Crescent Harbor EOD Training Range

Surface and Subsurface Testing Sites —There are three geographically distinct range sites in the Inland Waters where the Navy conducts surface and subsurface testing and some limited training. The Keyport Range Site is located in Kitsap County and includes portions of Liberty Bay and Port Orchard Reach (also known as Port Orchard Narrows). The Dabob Bay Range Complex (DBRC) Site is located in Hood Canal and Dabob Bay, in Jefferson, Kitsap, and Mason counties. The Carr Inlet OPAREA is located in southern Puget Sound.

The Keyport Range Site is located adjacent to NAVBASE Kitsap, Keyport, providing approximately 3.2 nm 2 for testing, including in-shore shallow water sites and a shallow lagoon to support integrated undersea warfare systems and vehicle maintenance and engineering activities. Water depth at the Keyport Range Site is less than 100 ft. (30.5 m). Underwater tracking of test activities can be accomplished by using temporary or portable range equipment. The Navy has conducted testing at the Keyport Range Site since 1914.

The DBRC Site includes the Dabob Bay and the Hood Canal from 1 mi. (1.6 km) south of the Hood Canal Bridge to the Hamma Hamma River, a total area of approximately 45.7 nm 2 . The Navy has conducted underwater testing at the DBRC Site since 1956, beginning with a control center at Whitney Point. The control center was subsequently moved to Zelatched Point

ing at the Keyport Range Site since 1914.

Dabob Bay is a deep-water area in Jefferson County approximately 14.5 nm 2 in size and contains an acoustic tracking range. The acoustic tracking space within the range is approximately 7.3 nm by 1.3 nm (9 nm 2 ) with a maximum depth of 600 ft. (182.9 m). The Dabob Bay tracking range, the only component of the DBRC Site with extensive acoustic monitoring instrumentation installed on the seafloor, provides for object tracking, communications, passive sensing, and target simulation. Many activities conducted within Dabob Bay are supported by land-based facilities at Zelatched Point.

Hood Canal averages a depth of 200 ft. (61 m) and is used for vessel sensor accuracy tests and launch and recovery of test systems where tracking is optional.

The Carr Inlet OPAREA is a quiet deep-water inland range approximately 12 nm 2 in size. It is located in an arm of water between Key Peninsula and Gig Harbor Peninsula. Its southern end is connected to the southern basin of Puget Sound. Northward, it separates McNeil Island and Fox Island as well as the peninsulas of Key and Gig Harbor. The acoustic tracking space within the range is approximately 6 nm by 2 nm with a maximum depth of 545 ft. (166 m). The Navy performed underwater acoustic testing at Carr Inlet from the 1950s through 2009, when activities were relocated to NAVBASE Kitsap, Bangor. While no permanently installed structures are present in the Carr Inlet OPAREA, the waterway remains a Navy-restricted area

Gig Harbor. The acoustic tracking space within the range is approximately 6 nm by 2 nm with a maximum depth of 545 ft. (166 m). The Navy performed underwater acoustic testing at Carr Inlet from the 1950s through 2009, when activities were relocated to NAVBASE Kitsap, Bangor. While no permanently installed structures are present in the Carr Inlet OPAREA, the waterway remains a Navy-restricted area.

Pierside Testing Facilities —In addition to the training and testing ranges, at which most of the training and testing assessed in this document occurs, the Navy conducts some testing at or near Navy piers. Most of this testing is sonar maintenance and testing while ships are in port for maintenance or system re-fitting. These piers within the Study Area are all within Puget Sound and include the NAVBASE Kitsap, Bremerton in Sinclair Inlet; NAVBASE Kitsap, Bangor Waterfront in Hood Canal, and Naval Station Everett.

Navy Surface Operations Areas— In addition to the areas mentioned above, there are two surface and subsurface operations areas used for Navy training and testing within the Inland Waters. Navy 3 OPAREA is a surface and subsurface area off the west coast of northern Whidbey Island. Navy 7 OPAREA is the surface and subsurface area that lies beneath R-6701. This area covers a total area of 61 nm 2 .

Western Behm Canal, Alaska

The Western Behm Canal is located in Southeast Alaska, near the city of Ketchikan, Alaska. SEAFAC is located in the Western Behm Canal and covers an area of 48 nm 2 . The Navy has been conducting testing activities at SEAFAC since 1992. The facility replaced the Santa Cruz Acoustic Range Facility in Southern California and is now the location for some acoustic testing previously conducted at the NSWC Carr Inlet Acoustic Range in Washington State.

SEAFAC is comprised of land-based facilities and in-water assets. The land-based facilities are located within 5.5 acres (2 hectares) on Back Island and are not included in the scope of this analysis

placed the Santa Cruz Acoustic Range Facility in Southern California and is now the location for some acoustic testing previously conducted at the NSWC Carr Inlet Acoustic Range in Washington State.

SEAFAC is comprised of land-based facilities and in-water assets. The land-based facilities are located within 5.5 acres (2 hectares) on Back Island and are not included in the scope of this analysis. The in-water assets include two sites: the underway site and the static site. These assets and the operational area of SEAFAC are located in five restricted areas. The underway site arrays are in Area 1. The static site is in Area 2. All associated underwater cabling and other devices associated with the underway site are located in Area 3. Area 4 provides a corridor for utility power and a phone cable. Area 5 is an operational area to allow for safe passage of local vessel traffic. Notifications of invoking restriction of Area 5 occur at least 72 hours prior to SEAFAC operations in accordance with 33 CFR 34.1275. During test periods, all vessels entering Area 5 are requested to contact SEAFAC to coordinate safe passage through the area. Area 5 defines the SEAFAC Study Area boundary, which is comprised only of the in-water area and excludes the land-based supporting facilities and operations.

The SEAFAC at-sea areas are:

• Restricted Areas 1 through 5. The five restricted areas are located within Western Behm Canal. The main purposes of the restricted areas are to provide for vessel and public safety, lessen acoustic encroachment from non-participating vessels, and prohibit certain activities that could damage SEAFAC's sensitive in-water acoustic instruments and associated cables. Area 5 encompasses the entire SEAFAC operations area.

• Underway Measurement Site. The underway measurement site is in the center of Western Behm Canal and is 5,000 yards (yd.) (4,572 m) wide and 12,000 yd. (10,973 m) long. The acoustic arrays are located at the center of this area (Area 1).

• Static Site

that could damage SEAFAC's sensitive in-water acoustic instruments and associated cables. Area 5 encompasses the entire SEAFAC operations area.

• Static Site. The static site is approximately 2 nm northwest of Back Island. During testing, a vessel is tethered between two surface barges. In most scenarios, the vessel submerges to conduct acoustic measurements. The static site is located at the center of Area 2.

• Area 3 and Area 4. These restricted areas provide protection to underwater cables and bottom-mounted equipment they encompass.

Bottom-moored acoustic measurement arrays are located in the middle of the site. These instrumented arrays are established for measuring vessel signatures when a vessel is underway (underway site) and is at rest and moored (static site). The instruments are passive arrays of hydrophones sensing the acoustic signature of the vessels ( i.e., the sounds emitted when sonar units are not in operation). Hydrophones on the arrays pick up noise in the water and transmit it to shore facilities, where the data are processed. SEAFAC's sensitive and well-positioned acoustic measurement equipment provides the ability to listen to and record the

The sensors at SEAFAC are passive and measure radiated noise in the water, such as machinery on submarines and other underwater vessels. Vessels do not use tactical mid-frequency active sonar while undergoing testing at SEAFAC. Active acoustic sources are used for communications, range calibration, and to provide position information for units operating submerged on the range

n to and record the

Description of Marine Mammals in the Area of the Specified Activities

Twenty-nine marine mammal species are known to occur in the Study Area, including seven mysticetes (baleen whales), 16 odontocetes (dolphins and toothed whales), and six pinnipeds (seals and sea lions). Among these species, there are 50 stocks managed by NMFS or the U.S. Fish and Wildlife Service (USFWS) in the U.S. Exclusive Economic Zone (EEZ). These species and their numbers are presented in Table 9. Consistent with NMFS most recent Pacific Stock Assessment Report, a single species may include multiple stocks recognized for management purposes (e.g., killer whale), while other species are grouped into a single stock due to limited species-specific information (e.g., beaked whales belonging to the genus Mesoplodon).

Table 9—Marine Mammals With Possible or Confirmed Presence Within the NWTT Study Area Common name Scientific name Stock Stock abundance ESA/MMPA North Pacific right whale Eubalaena japonica Eastern North Pacific 31 Endangered/Depleted. Humpback whale Megaptera novaeangliae Central North Pacific 10,103 Endangered/Depleted. California, Oregon, & Washington 1,918 Endangered/Depleted. Blue whale Balaenoptera musculus Eastern North Pacific 1,647 Endangered/Depleted. Fin whale Balaenoptera physalus Northeast Pacific 1,214 (minimum estimate) Endangered/Depleted. California, Oregon, & Washington 3,051 Endangered/Depleted. Sei whale Balaenoptera borealis Eastern North Pacific 126 Endangered/Depleted

103 Endangered/Depleted. California, Oregon, & Washington 1,918 Endangered/Depleted. Blue whale Balaenoptera musculus Eastern North Pacific 1,647 Endangered/Depleted. Fin whale Balaenoptera physalus Northeast Pacific 1,214 (minimum estimate) Endangered/Depleted. California, Oregon, & Washington 3,051 Endangered/Depleted. Sei whale Balaenoptera borealis Eastern North Pacific 126 Endangered/Depleted. Minke whale Balaenoptera acutorostrata Alaska Not available California, Oregon, & Washington 478 Gray whale Eschrichtius robustus Eastern North Pacific 19,126 Western North Pacific 155 Endangered/Depleted. Sperm whale Physeter macrocephalus North Pacific Not available Endangered/Depleted. California, Oregon, & Washington 971 Endangered/Depleted. Pygmy sperm whale Kogia breviceps California, Oregon, & Washington 579 Dwarf sperm whale Kogia sima California, Oregon, & Washington Not available Killer whale Orcinus orca Alaskan Resident 2,347 Northern Resident 261 West Coast Transient 243 Eastern North Pacific Offshore 240 Eastern North Pacific Southern Resident 85 (direct count) Endangered/Depleted. Short-finned pilot whale Globicephala macrorhynchus California, Oregon, & Washington 760 Short-beaked common dolphin Delphinus delphis California, Oregon, & Washington 411,211 Bottlenose dolphin Tursiops truncatus California, Oregon, & Washington Offshore 1,006 Striped dolphin Stenella coeruleoalba California, Oregon, & Washington 10,908 Pacific white-sided dolphin Lagenorhynchus obliquidens North Pacific 26,880 California, Oregon, & Washington 26,930 Northern right whale dolphin Lissodelphis borealis California, Oregon, & Washington 8,334 Risso's dolphin Grampus griseus California, Oregon, & Washington 6,272 Harbor porpoise Phocoena phocoena Southeast Alaska 11,146 Northern Oregon/WA Coast 21,487 Northern CA/southern OR 35,769 WA Inland Waters 10,682

olphin Lagenorhynchus obliquidens North Pacific 26,880 California, Oregon, & Washington 26,930 Northern right whale dolphin Lissodelphis borealis California, Oregon, & Washington 8,334 Risso's dolphin Grampus griseus California, Oregon, & Washington 6,272 Harbor porpoise Phocoena phocoena Southeast Alaska 11,146 Northern Oregon/WA Coast 21,487 Northern CA/southern OR 35,769 WA Inland Waters 10,682. Alaska 83,400 Dall's porpoise Phocoenoides dalli California, Oregon, & Washington 42,000 Cuvier's beaked whale Ziphius cavirostris Alaska Not available California, Oregon, & Washington 6,590 Baird's beaked whale Berardius bairdii Alaska Not available California, Oregon, & Washington 847 Mesoplodont beaked whales 1 Mesoplodon spp. California, Oregon, & Washington 694 Steller sea lion Eumetopias jubatus Eastern U.S. 63,160-78,198 California sea lion Zalophus californianus U.S. 296,750 Northern fur seal Callorhinus ursinus Eastern Pacific 639,545 Depleted. California Breeding 12,844 Guadalupe fur seal Arctocephalus townsendi Mexico 14,000-15,000 Threatened/Depleted. Northern elephant seal Mirounga angustirostris California Breeding 124,000 Harbor seal Phoca vitulina Southeast Alaska (Clarence Strait) 152,602 OR/WA Coast 24,732 California 30,196 WA Northern Inland Waters 11,036 Southern Puget Sound 1,568 Hood Canal 3,555. 2 1 In waters off the U.S. west coast, the Mesoplodon species M. carlhubbsi, M. ginkgodens, M. perrini, M. peruvianus, M. stejnegeri and M. densirostris have been grouped by NMFS into a single management unit ( Mesoplodon spp.) in the 2014 Pacific Stock Assessment report (Carretta et al., 2014). 2 The most recent SAR (2014) divided the harbor seals within the Inland Waters into three stocks: The Washington Northern Inland Waters stock; the Southern Puget Sound stock, and the Hood Canal stock. Based on recent discussion with regional NMFS subject matter experts and subsequent to the publication of the 2014 SAR, the Navy and NMFS applied research presented in London et al

tta et al., 2014). 2 The most recent SAR (2014) divided the harbor seals within the Inland Waters into three stocks: The Washington Northern Inland Waters stock; the Southern Puget Sound stock, and the Hood Canal stock. Based on recent discussion with regional NMFS subject matter experts and subsequent to the publication of the 2014 SAR, the Navy and NMFS applied research presented in London et al. (2012) to reevaluate the Hood Canal stock abundance. Using updated tag data from London et al. 2012, the count of harbor seals collected in 1999 (n=711) from aerial surveys (Jeffries et al., 2003) was corrected to account for harbor seal haulout behavior that most closely aligned with the season and time of day in which the original survey was conducted. The tag data showed that during this month and time of day, approximately 80 percent of the animals would be in the water. Therefore, the corrected Hood Canal stock abundance (based on the 1999 aerial survey) is calculated as 711/0.20 or 711*5 = 3,555. While this aerial survey data is considered out of date based on the standards of NOAA stock assessment reports, this revised Hood Canal harbor seal abundance represents the best available science based on publically available data.

Information on the status, distribution, abundance, and vocalizations of marine mammal species in the Study Area may be viewed in Chapter 4 of the LOA application ( http://www.nmfs.noaa.gov/pr/permits/incidental/military.htm ). Further information on the general biology and ecology of marine mammals is included in the NWTT DEIS/OEIS. In addition, NMFS publishes annual SARs for marine mammals, including stocks that occur within the Study Area ( http://www.nmfs.noaa.gov/pr/species/mammals; Carretta et al., 2014; Allen and Angliss, 2014).

Marine Mammal Hearing and Vocalizations

Cetaceans have an auditory anatomy that follows the basic mammalian pattern, with some changes to adapt to the demands of hearing underwater

EIS/OEIS. In addition, NMFS publishes annual SARs for marine mammals, including stocks that occur within the Study Area ( http://www.nmfs.noaa.gov/pr/species/mammals; Carretta et al., 2014; Allen and Angliss, 2014).

Marine Mammal Hearing and Vocalizations

Cetaceans have an auditory anatomy that follows the basic mammalian pattern, with some changes to adapt to the demands of hearing underwater. The typical mammalian ear is divided into an outer ear, middle ear, and inner ear. The outer ear is separated from the inner ear by a tympanic membrane, or eardrum. In terrestrial mammals, the outer ear, eardrum, and middle ear transmit airborne sound to the inner ear, where the sound waves are propagated through the cochlear fluid. Since the impedance of water is close to that of the tissues of a cetacean, the outer ear is not required to transduce sound energy as it does when sound waves travel from air to fluid (inner ear). Sound waves traveling through the inner ear cause the basilar membrane to vibrate. Specialized cells, called hair cells, respond to the vibration and produce nerve pulses that are transmitted to the central nervous system. Acoustic energy causes the basilar membrane in the cochlea to vibrate. Sensory cells at different positions along the basilar membrane are excited by different frequencies of sound (Pickles, 1998).

Marine mammal vocalizations often extend both above and below the range of human hearing; vocalizations with frequencies lower than 20 Hz are labeled as infrasonic and those higher than 20 kHz as ultrasonic (National Research Council (NRC), 2003; Figure 4-1). Measured data on the hearing abilities of cetaceans are sparse, particularly for the larger cetaceans such as the baleen whales. The auditory thresholds of some of the smaller odontocetes have been determined in captivity. It is generally believed that cetaceans should at least be sensitive to the frequencies of their own vocalizations

ltrasonic (National Research Council (NRC), 2003; Figure 4-1). Measured data on the hearing abilities of cetaceans are sparse, particularly for the larger cetaceans such as the baleen whales. The auditory thresholds of some of the smaller odontocetes have been determined in captivity. It is generally believed that cetaceans should at least be sensitive to the frequencies of their own vocalizations. Comparisons of the anatomy of cetacean inner ears and models of the structural properties and the response to vibrations of the ear's components in different species provide an indication of likely sensitivity to various sound frequencies. The ears of small toothed whales are optimized for receiving high-frequency sound, while baleen whale inner ears are best in low to infrasonic frequencies (Ketten, 1992; 1997; 1998).

Baleen whale vocalizations are composed primarily of frequencies below 1 kHz, and some contain fundamental frequencies as low as 16 Hz (Watkins et al., 1987; Richardson et al., 1995; Rivers, 1997; Moore et al., 1998; Stafford et al., 1999; Wartzok and Ketten, 1999) but can be as high as 24 kHz (humpback whale; Au et al., 2006). Clark and Ellison (2004) suggested that baleen whales use low-frequency sounds not only for long-range communication, but also as a simple form of echo ranging, using echoes to navigate and orient relative to physical features of the ocean. Information on auditory function in baleen whales is extremely lacking. Sensitivity to low-frequency sound by baleen whales has been inferred from observed vocalization frequencies, observed reactions to playback of sounds, and anatomical analyses of the auditory system. Although there is apparently much variation, the source levels of most baleen whale vocalizations lie in the range of 150-190 dB re 1 microPascal (µPa) at 1 m

on in baleen whales is extremely lacking. Sensitivity to low-frequency sound by baleen whales has been inferred from observed vocalization frequencies, observed reactions to playback of sounds, and anatomical analyses of the auditory system. Although there is apparently much variation, the source levels of most baleen whale vocalizations lie in the range of 150-190 dB re 1 microPascal (µPa) at 1 m. Low-

The toothed whales produce a wide variety of sounds, which include species-specific broadband “clicks” with peak energy between 10 and 200 kHz, individually variable “burst pulse” click trains, and constant frequency or frequency-modulated (FM) whistles ranging from 4 to 16 kHz (Wartzok and Ketten, 1999). The general consensus is that the tonal vocalizations (whistles) produced by toothed whales play an important role in maintaining contact between dispersed individuals, while broadband clicks are used during echolocation (Wartzok and Ketten, 1999). Burst pulses have also been strongly implicated in communication, with some scientists suggesting that they play an important role in agonistic encounters (McCowan and Reiss, 1995), while others have proposed that they represent “emotive” signals in a broader sense, possibly representing graded communication signals (Herzing, 1996). Sperm whales, however, are known to produce only clicks, which are used for both communication and echolocation (Whitehead, 2003). Most of the energy of toothed whale social vocalizations is concentrated near 10 kHz, with source levels for whistles as high as 100 to 180 dB re 1 µPa at 1 m (Richardson et al., 1995). No odontocete has been shown audiometrically to have acute hearing (<80 dB re 1 µPa) below 500 Hz (DoN, 2001). Sperm whales produce clicks, which may be used to echolocate (Mullins et al., 1988), with a frequency range from less than 100 Hz to 30 kHz and source levels up to 230 dB re 1 µPa 1 m or greater (Mohl et al., 2000)

istles as high as 100 to 180 dB re 1 µPa at 1 m (Richardson et al., 1995). No odontocete has been shown audiometrically to have acute hearing (<80 dB re 1 µPa) below 500 Hz (DoN, 2001). Sperm whales produce clicks, which may be used to echolocate (Mullins et al., 1988), with a frequency range from less than 100 Hz to 30 kHz and source levels up to 230 dB re 1 µPa 1 m or greater (Mohl et al., 2000).

Brief Background on Sound

An understanding of the basic properties of underwater sound is necessary to comprehend many of the concepts and analyses presented in this document. A summary is included below.

Sound is a wave of pressure variations propagating through a medium ( e.g., water). Pressure variations are created by compressing and relaxing the medium. Sound measurements can be expressed in two forms: intensity and pressure. Acoustic intensity is the average rate of energy transmitted through a unit area in a specified direction and is expressed in watts per square meter (W/m 2 ). Acoustic intensity is rarely measured directly, but rather from ratios of pressures; the standard reference pressure for underwater sound is 1 µPa; for airborne sound, the standard reference pressure is 20 µPa (Richardson et al., 1995).

Acousticians have adopted a logarithmic scale for sound intensities, which is denoted in decibels (dB). Decibel measurements represent the ratio between a measured pressure value and a reference pressure value (in this case 1 µPa or, for airborne sound, 20 µPa). The logarithmic nature of the scale means that each 10-dB increase is a ten-fold increase in acoustic power (and a 20-dB increase is then a 100-fold increase in power; and a 30-dB increase is a 1,000-fold increase in power). A ten-fold increase in acoustic power does not mean that the sound is perceived as being ten times louder, however. Humans perceive a 10-dB increase in sound level as a doubling of loudness, and a 10-dB decrease in sound level as a halving of loudness

fold increase in acoustic power (and a 20-dB increase is then a 100-fold increase in power; and a 30-dB increase is a 1,000-fold increase in power). A ten-fold increase in acoustic power does not mean that the sound is perceived as being ten times louder, however. Humans perceive a 10-dB increase in sound level as a doubling of loudness, and a 10-dB decrease in sound level as a halving of loudness. The term “sound pressure level” implies a decibel measure and a reference pressure that is used as the denominator of the ratio. Throughout this document, NMFS uses 1 µPa (denoted re: 1µPa) as a standard reference pressure unless noted otherwise.

It is important to note that decibel values underwater and decibel values in air are not the same (different reference pressures and densities/sound speeds between media) and should not be directly compared. Because of the different densities of air and water and the different decibel standards ( i.e., reference pressures) in air and water, a sound with the same level in air and in water would be approximately 62 dB lower in air. Thus, a sound that measures 160 dB (re 1 µPa) underwater would have the same approximate effective level as a sound that is 98 dB (re 20 µPa) in air.

Sound frequency is measured in cycles per second, or Hertz (abbreviated Hz), and is analogous to musical pitch; high-pitched sounds contain high frequencies and low-pitched sounds contain low frequencies. Natural sounds in the ocean span a huge range of frequencies: from earthquake noise at 5 Hz to harbor porpoise clicks at 150,000 Hz (150 kHz). These sounds are so low or so high in pitch that humans cannot even hear them; acousticians call these infrasonic (typically below 20 Hz) and ultrasonic (typically above 20,000 Hz) sounds, respectively. A single sound may be made up of many different frequencies together

in the ocean span a huge range of frequencies: from earthquake noise at 5 Hz to harbor porpoise clicks at 150,000 Hz (150 kHz). These sounds are so low or so high in pitch that humans cannot even hear them; acousticians call these infrasonic (typically below 20 Hz) and ultrasonic (typically above 20,000 Hz) sounds, respectively. A single sound may be made up of many different frequencies together. Sounds made up of only a small range of frequencies are called “narrowband”, and sounds with a broad range of frequencies are called “broadband”; explosives are an example of a broadband sound source and active tactical sonars are an example of a narrowband sound source.

When considering the influence of various kinds of sound on the marine environment, it is necessary to understand that different kinds of marine life are sensitive to different frequencies of sound. Current data indicate that not all marine mammal species have equal hearing capabilities (Richardson et al., 1995; Southall et al., 1997; Wartzok and Ketten, 1999; Au and Hastings, 2008).

Southall et al. (2007) designated “functional hearing groups” for marine mammals based on available behavioral data; audiograms derived from auditory evoked potentials; anatomical modeling; and other data. Southall et al. (2007) also estimated the lower and upper frequencies of functional hearing for each group. However, animals are less sensitive to sounds at the outer edges of their functional hearing range and are more sensitive to a range of frequencies within the middle of their functional hearing range. Note that no direct measurements of hearing ability have been successfully completed for low-frequency cetaceans

) also estimated the lower and upper frequencies of functional hearing for each group. However, animals are less sensitive to sounds at the outer edges of their functional hearing range and are more sensitive to a range of frequencies within the middle of their functional hearing range. Note that no direct measurements of hearing ability have been successfully completed for low-frequency cetaceans. 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 (13 species of mysticetes): Functional hearing estimates occur between approximately 7 Hz and 30 kilohertz (kHz) (extended from 22 kHz based on data indicating that some mysticetes can hear above 22 kHz; Watkins, 1986; Ketten, 1998; Houser et al., 2001; Au et al., 2006; Lucifredi and Stein, 2007; Ketten et al., 2007; Parks et al., 2007a; Ketten and Mountain, 2009; Tubelli et al., 2012);

• Mid-frequency cetaceans (larger toothed whales, beaked whales, and most delphinids): Functional hearing is estimated to occur between approximately 150 Hz and 160 kHz, with best hearing from 10 to less than 100 kHz (Johnson, 1967; White, 1977; Richardson et al., 1995; Szymanski et al., 1999; Kastelein et al., 2003; Finneran et al., 2005a, 2009; Nachtigall et al., 2005, 2008; Yuen et al., 2005; et al., 2007; Au and Hastings, 2008; Houser et al., 2008; Pacini et al., 2010, 2011; Schlundt et al., 2011);

• High-frequency cetaceans (porpoises, river dolphins, and members of the genera Kogia and Cephalorhynchus ; including two members of the genus Lagenorhynchus, including the hourglass dolphin, on the basis of recent echolocation data and genetic data [May-Collado and Agnarsson, 2006; Kyhn et al., 2009, 2010; Tougaard et al., 2010]): Functional hearing is estimated to occur between approximately 200 Hz and 180 kHz (Popov and Supin, 1990a,b; Kastelein et

d members of the genera Kogia and Cephalorhynchus ; including two members of the genus Lagenorhynchus, including the hourglass dolphin, on the basis of recent echolocation data and genetic data [May-Collado and Agnarsson, 2006; Kyhn et al., 2009, 2010; Tougaard et al., 2010]): Functional hearing is estimated to occur between approximately 200 Hz and 180 kHz (Popov and Supin, 1990a,b; Kastelein et al., 2002; Popov et al., 2005); and

• Pinnipeds in water; Phocidae (true seals): Functional hearing is estimated to occur between approximately 75 Hz to 100 kHz, with best hearing between 1-50 kHz (Møhl, 1968; Terhune and Ronald, 1971, 1972; Richardson et al., 1995; Kastak and Schusterman, 1999; Reichmuth, 2008; Kastelein et al., 2009);

• Pinnipeds in water; Otariidae (eared seals): Functional hearing is estimated to occur between 100 Hz and 40 kHz for Otariidae, with best hearing between 2-48 kHz (Schusterman et al., 1972; Moore and Schusterman, 1987; Babushina et al., 1991; Richardson et al., 1995; Kastak and Schusterman, 1998; Kastelein et al., 2005a; Mulsow and Reichmuth, 2007; Mulsow et al., 2011a, b).

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 et al., 2013).

Concurrent with the development of NOAA's Ocean Noise Strategy and draft “Guidance for Assessing the Effects of Anthropogenic Sound on Marine Mammals,” NMFS is currently considering additional modifications to some of the functional hearing ranges proposed by Southall et al. (2007). As more data from more species and/or individuals become available, these estimated hearing ranges may require additional modifications.

When sound travels (propagates) from its source, its loudness decreases as the distance traveled by the sound increases

Mammals,” NMFS is currently considering additional modifications to some of the functional hearing ranges proposed by Southall et al. (2007). As more data from more species and/or individuals become available, these estimated hearing ranges may require additional modifications.

When sound travels (propagates) from its source, its loudness decreases as the distance traveled by the sound increases. Thus, the loudness of a sound at its source is higher than the loudness of that same sound a kilometer away. Acousticians often refer to the loudness of a sound at its source (typically referenced to one meter from the source) as the source level and the loudness of sound elsewhere as the received level ( i.e., typically the receiver). For example, a humpback whale 3 km from a device that has a source level of 230 dB may only be exposed to sound that is 160 dB loud, depending on how the sound travels through water ( e.g., spherical spreading [3 dB reduction with doubling of distance] was used in this example). As a result, it is important to understand the difference between source levels and received levels when discussing the loudness of sound in the ocean or its impacts on the marine environment.

vironment.

As sound travels from a source, its propagation in water is influenced by various physical characteristics, including water temperature, depth, salinity, and surface and bottom properties that cause refraction, reflection, absorption, and scattering of sound waves. Oceans are not homogeneous and the contribution of each of these individual factors is extremely complex and interrelated. The physical characteristics that determine the sound's speed through the water will change with depth, season, geographic location, and with time of day (as a result, in actual active sonar operations, crews will measure oceanic conditions, such as sea water temperature and depth, to calibrate models that determine the path the sonar signal will take as it travels through the ocean and how strong the sound signal will be at a given range along a particular transmission path). As sound travels through the ocean, the intensity associated with the wavefront diminishes, or attenuates. This decrease in intensity is referred to as propagation loss, also commonly called transmission loss.

Metrics Used in This Document

This section includes a brief explanation of the two sound measurements (sound pressure level (SPL) and sound exposure level (SEL)) frequently used to describe sound levels in the discussions of acoustic effects in this document.

Sound pressure level (SPL)—Sound pressure is the sound force per unit area, and is usually measured in micropascals (µPa), where 1 Pa is the pressure resulting from a force of one newton exerted over an area of one square meter. SPL is expressed as the ratio of a measured sound pressure and a reference level.

ea of one square meter. SPL is expressed as the ratio of a measured sound pressure and a reference level.

SPL (in dB) = 20 log (pressure/reference pressure) The commonly used reference pressure level in underwater acoustics is 1 µPa, and the units for SPLs are dB re: 1 µPa. SPL is an instantaneous pressure measurement and can be expressed as the peak, the peak-peak, or the root mean square (rms). Root mean square pressure, which is the square root of the arithmetic average of the squared instantaneous pressure values, is typically used in discussions of the effects of sounds on vertebrates and all references to SPL in this document refer to the root mean square. SPL does not take the duration of exposure into account. SPL is the applicable metric used in the risk continuum, which is used to estimate behavioral harassment takes (see Level B Harassment Risk Function (Behavioral Harassment) Section).

Sound exposure level (SEL)—SEL is an energy metric that integrates the squared instantaneous sound pressure over a stated time interval. The units for SEL are dB re: 1 µPa 2 -s. Below is a simplified formula for SEL.

SEL = SPL + 10 log (duration in seconds) As applied to active sonar, the SEL includes both the SPL of a sonar ping and the total duration. Longer duration pings and/or pings with higher SPLs will have a higher SEL. If an animal is exposed to multiple pings, the SEL in each individual ping is summed to calculate the cumulative SEL. The cumulative SEL depends on the SPL, duration, and number of pings received. The thresholds that NMFS uses to indicate at what received level the onset of temporary threshold shift (TTS) and permanent threshold shift (PTS) in hearing are likely to occur are expressed as cumulative SEL.

Potential Effects of Specified Activities on Marine Mammals

The Navy has requested authorization for the take of marine mammals that may occur incidental to training and testing activities in the Study Area

NMFS uses to indicate at what received level the onset of temporary threshold shift (TTS) and permanent threshold shift (PTS) in hearing are likely to occur are expressed as cumulative SEL.

Potential Effects of Specified Activities on Marine Mammals

The Navy has requested authorization for the take of marine mammals that may occur incidental to training and testing activities in the Study Area. The Navy has analyzed potential impacts to marine mammals from impulsive and non-impulsive sound sources and vessel strike.

Other potential impacts to marine mammals from training activities in the Study Area were analyzed in the Navy's January 2014 NWTT DEIS/OEIS, in consultation with NMFS as a cooperating agency, and determined to be unlikely to result in marine mammal harassment. Therefore, the Navy has not requested authorization for take of marine mammals that might occur incidental to other components of their proposed activities. In this document, NMFS analyzes the potential effects on marine mammals from exposure to non-impulsive sound sources (sonar and other active acoustic sources), impulsive sound sources (underwater detonations), and vessel strikes.

For the purpose of MMPA authorizations, NMFS' effects assessments serve four primary purposes: (1) To prescribe the permissible methods of taking ( i.e., Level B harassment (behavioral harassment), Level A harassment (injury), or mortality, including an identification of the number and types of take that could occur by harassment 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 activity would have a negligible impact on the affected species or stocks of marine mammals (based on the likelihood that the activity would adversely affect the species or stock through effects on annual rates of recruitment or survival); (3) to determine whether the specified activity would have an unmitigable adverse impact on the availab

.e., mitigation); (2) to determine whether the specified activity would have a negligible impact on the affected species or stocks of marine mammals (based on the likelihood that the activity would adversely affect the species or stock through effects on annual rates of recruitment or survival); (3) to determine whether the specified activity would have an unmitigable adverse impact on the availability of the species or stock(s) for subsistence uses; and (4) to prescribe requirements pertaining to monitoring and reporting.

More specifically, for activities involving non-impulsive or impulsive sources, NMFS' analysis will identify the probability of lethal responses, physical trauma, sensory impairment (permanent and temporary threshold shifts and acoustic masking), physiological responses (particular stress responses), behavioral disturbance (that rises to the level of harassment), and social responses (effects to social relationships) that would be classified as a take and whether such take would have a negligible impact on such species or stocks. This section focuses qualitatively on the different ways that non-impulsive and impulsive sources may affect marine mammals (some of which NMFS would not classify as harassment). Then, in the Estimated Take of Marine Mammals section, the potential effects to marine mammals from non-impulsive and impulsive sources will be related to the MMPA definitions of Level A and Level B harassment, along with the potential effects from vessel strikes, and we will attempt to quantify those effects.

Non-Impulsive Sources

Direct Physiological Effects

h the potential effects from vessel strikes, and we will attempt to quantify those effects.

Non-Impulsive Sources

Direct Physiological Effects

Based on the literature, there are two basic ways that non-impulsive sources might directly result in physical trauma or damage: Noise-induced loss of hearing sensitivity (more commonly-called “threshold shift”) and acoustically mediated bubble growth. Separately, an animal's behavioral reaction to an acoustic exposure could 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 ( i.e., sounds must be louder for an animal to detect them) following exposure to an intense sound or sound for long duration, it is referred to as a noise-induced threshold shift (TS). An animal can experience temporary threshold shift (TTS) or permanent threshold shift (PTS). TTS can last from minutes or hours to days ( i.e., there is complete recovery), can occur in specific frequency ranges ( i.e., an animal might only have a temporary loss of hearing sensitivity between the frequencies of 1 and 10 kHz), and can be of varying amounts (for example, an animal's hearing sensitivity might be reduced initially by only 6 dB or reduced by 30 dB). PTS is permanent, but some recovery is possible. PTS can also occur in a specific frequency range and amount as mentioned above for TTS.

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)

ught 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. As amplitude and duration of sound exposure increase, so, generally, does the amount of TS, along with the recovery time. For intermittent sounds, less TS could occur than compared to a continuous exposure with the same energy (some recovery could occur between intermittent exposures depending on the duty cycle between sounds) (Kryter et al., 1966; Ward, 1997). For example, one short but loud (higher SPL) sound exposure may induce the same impairment as one longer but softer 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, prolonged exposure to sounds 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). Although in the case of mid- and high-frequency active sonar (MFAS/HFAS), animals are not expected to be exposed to levels high enough or durations long enough to result in PTS.

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)

ugh to result in PTS.

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. For marine mammals, published data are limited to the captive bottlenose dolphin, beluga, harbor porpoise, and Yangtze finless porpoise (Finneran et al., 2000, 2002b, 2003, 2005a, 2007, 2010a, 2010b; Finneran and Schlundt, 2010; Lucke et al., 2009; Mooney et al., 2009a, 2009b; Popov et al., 2011a, 2011b; Kastelein et al., 2012a; Schlundt et al., 2000; Nachtigall et al., 2003, 2004). For pinnipeds in water, data are limited to measurements of TTS in harbor seals, an elephant seal, and California sea lions (Kastak et al., 1999, 2005; Kastelein et al., 2012b).

Marine mammal hearing plays a critical role in communication with conspecifics, and 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 occurs during a time where ambient noise is lower and there are not as many competing sounds present

h 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 occurs during a time 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 time when communication is critical for successful mother/calf interactions could have more serious impacts. Also, depending on the degree and frequency range, the effects of PTS on an animal could range in severity, although it is considered generally more serious because it is a permanent et al., 2007), so one can infer that strategies exist for coping with this condition to some degree, though likely not without cost.

Acoustically Mediated Bubble Growth —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

redicted 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 of sonar pings or explosion sounds 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)

urs 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. 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). 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). More recent work conducted by Crum et al

h, there is considerable disagreement among scientists as to its likelihood (Piantadosi and Thalmann, 2004; Evans and Miller, 2003). 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). More recent 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). Although it has been argued that traumas from some recent beaked whale strandings are consistent with gas emboli and bubble-induced tissue separations (Jepson et al., 2003), there is no conclusive evidence of this. However, 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 particularly vulnerable to sonar exposures. Further investigation is needed to further assess the potential validity of these hypotheses. More information regarding hypotheses that attempt to explain how behavioral responses to non-impulsive sources can lead to strandings is included in the Stranding and Mortality section.

Acoustic Masking

Marine mammals use acoustic signals for a variety of purposes, which differ among species, but include communication between individuals, navigation, foraging, reproduction, and learning about their environment (Erbe and Farmer, 2000; Tyack, 2000). Masking, or auditory interference, generally occurs when sounds in the environment are louder than and of a similar frequency to, auditory signals an animal is trying to receive

c signals for a variety of purposes, which differ among species, but include communication between individuals, navigation, foraging, reproduction, and learning about their environment (Erbe and Farmer, 2000; Tyack, 2000). Masking, or auditory interference, generally occurs when sounds in the environment are louder than and of a similar frequency to, auditory signals an animal is trying to receive. Masking is a phenomenon that affects animals that are trying to receive acoustic information about their environment, including sounds from other members of their species, predators, prey, and sounds that allow them to orient in their environment. Masking these acoustic signals can disturb the behavior of individual animals, groups of animals, or entire populations.

The extent of the masking interference depends on the spectral, temporal, and spatial relationships between the signals an animal is trying to receive and the masking noise, in addition to other factors. 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.

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

an 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 recent 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.

As mentioned previously, the functional hearing ranges of mysticetes, odontocetes, and pinnipeds underwater all encompass the frequencies of the sonar sources used in the Navy's MFAS/HFAS training 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. For hull-mounted sonar, which accounts for the largest takes of marine mammals (because of the source strength and number of hours it's conducted), the pulse length and low duty cycle of the MFAS/HFAS signal makes it less likely that masking would occur as a result

used by the Navy. The closer the characteristics of the masking signal to the signal of interest, the more likely masking is to occur. For hull-mounted sonar, which accounts for the largest takes of marine mammals (because of the source strength and number of hours it's 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 animals 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 will combine several of these strategies to compensate for high levels of background noise

guishability 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 will combine several of these strategies to compensate for high levels of background noise. Anthropogenic sounds that reduce the signal-to-noise ratio of animal vocalizations, increase the masked auditory thresholds of animals listening for such vocalizations, or reduce the active space of an animal's vocalizations impair communication between animals. Most animals that vocalize have evolved strategies to compensate for the effects of short-term or temporary increases in background or ambient noise on their songs or calls. Although the fitness consequences of these vocal adjustments remain unknown, like most other trade-offs animals must make, some of these strategies probably come at a cost (Patricelli et al., 2006). For example, vocalizing more loudly in noisy environments may have energetic costs that decrease the net benefits of vocal adjustment and alter a bird's energy budget (Brumm, 2004; Wood and Yezerinac, 2006). Shifting songs and calls to higher frequencies may also impose energetic costs (Lambrechts, 1996).

Stress Responses

Classic stress responses begin when an animal's central nervous system perceives a potential threat to its homeostasis. That perception triggers stress responses regardless of whether a stimulus actually threatens the animal; the mere perception of a threat is sufficient to trigger a stress response (Moberg, 2000; Sapolsky et al., 2005; Seyle, 1950). Once an animal's central nervous system perceives a threat, it mounts a biological response or defense that consists of a combination of the four general biological defense responses: behavioral responses, autonomic nervous system responses, neuroendocrine responses, or immune responses

ption of a threat is sufficient to trigger a stress response (Moberg, 2000; Sapolsky et al., 2005; Seyle, 1950). Once an animal's central nervous system perceives a threat, it mounts a biological response or defense that consists of a combination of the four general biological defense responses: behavioral responses, autonomic nervous system responses, neuroendocrine responses, or immune responses.

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

An animal's third line of defense to stressors involves its neuroendocrine systems; the system that has received the most study has been the hypothalmus-pituitary-adrenal system (also known as the HPA axis in mammals or the hypothalamus-pituitary-interrenal axis in fish and some reptiles). Unlike stress responses associated with the autonomic nervous system, virtually all neuro-endocrine functions that are affected by stress—including immune competence, reproduction, metabolism, and behavior—are regulated by pituitary hormones. Stress-induced changes in the secretion of pituitary hormones have been implicated in failed reproduction (Moberg, 1987; Rivier, 1995), altered metabolism (Elasser et al., 2000), reduced immune competence (Blecha, 2000), and behavioral disturbance

endocrine functions that are affected by stress—including immune competence, reproduction, metabolism, and behavior—are regulated by pituitary hormones. Stress-induced changes in the secretion of pituitary hormones have been implicated in failed reproduction (Moberg, 1987; Rivier, 1995), altered metabolism (Elasser et al., 2000), reduced immune competence (Blecha, 2000), and behavioral disturbance. Increases in the circulation of glucocorticosteroids (cortisol, corticosterone, and aldosterone in marine mammals; see Romano et al., 2004) have been equated with stress for many years.

The primary distinction between stress (which is adaptive and does not normally place an animal at risk) and distress is the biotic cost of the response. During a stress response, an animal uses glycogen stores that can be quickly replenished once the stress is alleviated. In such circumstances, the cost of the stress response would not pose a risk to the animal's welfare. However, when an animal does not have sufficient energy reserves to satisfy the energetic costs of a stress response, energy resources must be diverted from other biotic function, which impairs those functions that experience the diversion. For example, when mounting a stress response diverts energy away from growth in young animals, those animals may experience stunted growth. When mounting a stress response diverts energy from a fetus, an animal's reproductive success and its fitness will suffer. In these cases, the animals will have entered a pre-pathological or pathological state which is called “distress” (Seyle, 1950) or “allostatic loading” (McEwen and Wingfield, 2003)

e diverts energy away from growth in young animals, those animals may experience stunted growth. When mounting a stress response diverts energy from a fetus, an animal's reproductive success and its fitness will suffer. In these cases, the animals will have entered a pre-pathological or pathological state which is called “distress” (Seyle, 1950) or “allostatic loading” (McEwen and Wingfield, 2003). This pathological state will last until the animal replenishes its biotic

Relationships between these physiological mechanisms, animal behavior, and the costs of stress responses have also been documented fairly well through controlled experiments; because this physiology exists in every vertebrate that has been studied, it is not surprising that stress responses and their costs have been documented in both laboratory and free-living animals (for examples see, Holberton et al., 1996; Hood et al., 1998; Jessop et al., 2003; Krausman et al., 2004; Lankford et al., 2005; Reneerkens et al., 2002; Thompson and Hamer, 2000). Information has also been collected on the physiological responses of marine mammals to exposure to anthropogenic sounds (Fair and Becker, 2000; Romano et al., 2002; Wright et al., 2008). For example, Rolland et al. (2012) found that noise reduction from reduced ship traffic in the Bay of Fundy was associated with decreased stress in North Atlantic right whales. In a conceptual model developed by the Population Consequences of Acoustic Disturbance (PCAD) working group, serum hormones were identified as possible indicators of behavioral effects that are translated into altered rates of reproduction and mortality. The Office of Naval Research hosted a workshop (Effects of Stress on Marine Mammals Exposed to Sound) in 2009 that focused on this very topic (ONR, 2009)

ceptual model developed by the Population Consequences of Acoustic Disturbance (PCAD) working group, serum hormones were identified as possible indicators of behavioral effects that are translated into altered rates of reproduction and mortality. The Office of Naval Research hosted a workshop (Effects of Stress on Marine Mammals Exposed to Sound) in 2009 that focused on this very topic (ONR, 2009).

Studies of other marine animals and terrestrial animals would also lead us to expect some marine mammals to experience physiological stress responses and, perhaps, physiological responses that would be classified as “distress” upon exposure to high frequency, mid-frequency and low-frequency sounds. For example, Jansen (1998) reported on the relationship between acoustic exposures and physiological responses that are indicative of stress responses in humans (for example, elevated respiration and increased heart rates). Jones (1998) reported on reductions in human performance when faced with acute, repetitive exposures to acoustic disturbance. Trimper et al. (1998) reported on the physiological stress responses of osprey to low-level aircraft noise while Krausman et al. (2004) reported on the auditory and physiology stress responses of endangered Sonoran pronghorn to military overflights. Smith et al. (2004a, 2004b), for example, identified noise-induced physiological transient stress responses in hearing-specialist fish ( i.e., goldfish) that accompanied short- and long-term hearing losses. Welch and Welch (1970) reported physiological and behavioral stress responses that accompanied damage to the inner ears of fish and several mammals.

Hearing is one of the primary senses marine mammals use to gather information about their environment and to communicate with conspecifics

s responses in hearing-specialist fish ( i.e., goldfish) that accompanied short- and long-term hearing losses. Welch and Welch (1970) reported physiological and behavioral stress responses that accompanied damage to the inner ears of fish and several mammals.

Hearing is one of the primary senses marine mammals use to gather information about their environment and to communicate with conspecifics. Although empirical information on the relationship between sensory impairment (TTS, PTS, and acoustic masking) on marine mammals remains limited, it seems reasonable to assume that reducing an animal's ability to gather information about its environment and to communicate with other members of its species would be stressful for animals that use hearing as their primary sensory mechanism. Therefore, we assume that acoustic exposures sufficient to trigger onset PTS or TTS would be accompanied by physiological stress responses because terrestrial animals exhibit those responses under similar conditions (NRC, 2003). More importantly, marine mammals might experience stress responses at received levels lower than those necessary to trigger onset TTS. Based on empirical studies of the time required to recover from stress responses (Moberg, 2000), we also assume that stress responses are likely to persist beyond the time interval required for animals to recover from TTS and might result in pathological and pre-pathological states that would be as significant as behavioral responses to TTS.

Behavioral Disturbance

Behavioral responses to sound are highly variable and context-specific. Many different variables can influence an animal's perception of and response to (nature and magnitude) an acoustic event. An animal's prior experience with a sound or sound source effects whether it is less likely (habituation) or more likely (sensitization) to respond to certain sounds in the future (animals can also be innately pre-disposed to respond to certain sounds in certain ways) (Southall et al., 2007)

variables can influence an animal's perception of and response to (nature and magnitude) an acoustic event. An animal's prior experience with a sound or sound source effects whether it is less likely (habituation) or more likely (sensitization) to respond to certain sounds in the future (animals can also be innately pre-disposed to respond to certain sounds in certain ways) (Southall et al., 2007). Related to the sound itself, the perceived nearness of the sound, bearing of the sound (approaching vs. retreating), similarity of a sound to biologically relevant sounds in the animal's environment ( i.e., calls of predators, prey, or conspecifics), and familiarity of the sound may affect the way an animal responds to the sound (Southall et al., 2007). Individuals (of different age, gender, reproductive status, etc.) among most populations will have variable hearing capabilities, and differing behavioral sensitivities to sounds that will be affected by prior conditioning, experience, and current activities of those individuals. Often, specific acoustic features of the sound and contextual variables ( i.e., proximity, duration, or recurrence of the sound or the current behavior that the marine mammal is engaged in or its prior experience), as well as entirely separate factors such as the physical presence of a nearby vessel, may be more relevant to the animal's response than the received level alone.

Exposure of marine mammals to sound sources can result in no response or responses including, but not limited to: increased alertness; orientation or attraction to a sound source; vocal modifications; cessation of feeding; cessation of social interaction; alteration of movement or diving behavior; habitat abandonment (temporary or permanent); and, in severe cases, panic, flight, stampede, or stranding, potentially resulting in death (Southall et al., 2007). A review of marine mammal responses to anthropogenic sound was first conducted by Richardson and others in 1995

ource; vocal modifications; cessation of feeding; cessation of social interaction; alteration of movement or diving behavior; habitat abandonment (temporary or permanent); and, in severe cases, panic, flight, stampede, or stranding, potentially resulting in death (Southall et al., 2007). A review of marine mammal responses to anthropogenic sound was first conducted by Richardson and others in 1995. A more recent review (Nowacek et al., 2007) addresses studies conducted since 1995 and focuses on observations where the received sound level of the exposed marine mammal(s) was known or could be estimated. The following sub-sections provide examples of behavioral responses that provide an idea of the variability in behavioral responses that would be expected given the differential sensitivities of marine mammal species to sound and the wide range of potential acoustic sources to which a marine mammal may be exposed. Estimates of the types of behavioral responses that could occur for a given sound exposure should be determined from the literature that is available for each species, or extrapolated from closely related species when no information exists.

Flight Response —A flight response is a dramatic change in normal movement to a directed and rapid movement away from the perceived location of a sound source. Relatively little information on flight responses of marine mammals to anthropogenic signals exist, although observations of flight responses to the presence of predators have occurred (Connor and Heithaus, 1996). Flight responses have been speculated as being a component of marine mammal strandings associated with sonar activities (Evans and England, 2001).

dings associated with sonar activities (Evans and England, 2001).

Response to Predator —Evidence suggests that at least some marine mammals have the ability to acoustically identify potential predators. For example, harbor seals that reside in et al., 2002), a capability that should increase survivorship while reducing the energy required for attending to and responding to all killer whale calls. The occurrence of masking or hearing impairment provides a means by which marine mammals may be prevented from responding to the acoustic cues produced by their predators. Whether or not this is a possibility depends on the duration of the masking/hearing impairment and the likelihood of encountering a predator during the time that predator cues are impeded.

Diving —Changes in dive behavior can vary widely. They may consist of increased or decreased dive times and surface intervals as well as changes in the rates of ascent and descent during a dive. Variations in dive behavior may reflect interruptions in biologically significant activities ( e.g., foraging) or they may be of little biological significance. Variations in dive behavior may also expose an animal to potentially harmful conditions ( e.g., increasing the chance of ship-strike) or may serve as an avoidance response that enhances survivorship. The impact of a variation in diving resulting from an acoustic exposure depends on what the animal is doing at the time of the exposure and the type and magnitude of the response.

Nowacek et al. (2004) reported disruptions of dive behaviors in foraging North Atlantic right whales when exposed to an alerting stimulus, an action, they noted, that could lead to an increased likelihood of ship strike. However, the whales did not respond to playbacks of either right whale social sounds or vessel noise, highlighting the importance of the sound characteristics in producing a behavioral reaction

(2004) reported disruptions of dive behaviors in foraging North Atlantic right whales when exposed to an alerting stimulus, an action, they noted, that could lead to an increased likelihood of ship strike. However, the whales did not respond to playbacks of either right whale social sounds or vessel noise, highlighting the importance of the sound characteristics in producing a behavioral reaction. Conversely, Indo-Pacific humpback dolphins have been observed to dive for longer periods of time in areas where vessels were present and/or approaching (Ng and Leung, 2003). In both of these studies, the influence of the sound exposure cannot be decoupled from the physical presence of a surface vessel, thus complicating interpretations of the relative contribution of each stimulus to the response. Indeed, the presence of surface vessels, their approach, and speed of approach, seemed to be significant factors in the response of the Indo-Pacific humpback dolphins (Ng and Leung, 2003). Low frequency signals of the Acoustic Thermometry of Ocean Climate (ATOC) sound source were not found to affect dive times of humpback whales in Hawaiian waters (Frankel and Clark, 2000) or to overtly affect elephant seal dives (Costa et al., 2003). They did, however, produce subtle effects that varied in direction and degree among the individual seals, illustrating the equivocal nature of behavioral effects and consequent difficulty in defining and predicting them.

Due to past incidents of beaked whale strandings associated with sonar operations, feedback paths are provided between avoidance and diving and indirect tissue effects. This feedback accounts for the hypothesis that variations in diving behavior and/or avoidance responses can possibly result in nitrogen tissue supersaturation and nitrogen off-gassing, possibly to the point of deleterious vascular bubble formation (Jepson et al., 2003). Although hypothetical, discussions surrounding this potential process are controversial

e and diving and indirect tissue effects. This feedback accounts for the hypothesis that variations in diving behavior and/or avoidance responses can possibly result in nitrogen tissue supersaturation and nitrogen off-gassing, possibly to the point of deleterious vascular bubble formation (Jepson et al., 2003). Although hypothetical, discussions surrounding this potential process are controversial.

Foraging —Disruption of feeding behavior can be difficult to correlate with anthropogenic sound exposure, so it is usually inferred by observed displacement from known foraging areas, the appearance of secondary indicators ( e.g., bubble nets or sediment plumes), or changes in dive behavior. Noise from seismic surveys was not found to impact the feeding behavior in western grey whales off the coast of Russia (Yazvenko et al., 2007) and sperm whales engaged in foraging dives did not abandon dives when exposed to distant signatures of seismic airguns (Madsen et al., 2006). However, Miller et al. (2009) reported buzz rates (a proxy for feeding) 19 percent lower during exposure to distant signatures of seismic airguns. Balaenopterid whales exposed to moderate low-frequency signals similar to the ATOC sound source demonstrated no variation in foraging activity (Croll et al., 2001), whereas five out of six North Atlantic right whales exposed to an acoustic alarm interrupted their foraging dives (Nowacek et al., 2004). Although the received sound pressure levels were similar in the latter two studies, the frequency, duration, and temporal pattern of signal presentation were different. These factors, as well as differences in species sensitivity, are likely contributing factors to the differential response. Blue whales exposed to simulated mid-frequency sonar in the Southern California Bight were less likely to produce low frequency calls usually associated with feeding behavior (Melcón et al., 2012)

requency, duration, and temporal pattern of signal presentation were different. These factors, as well as differences in species sensitivity, are likely contributing factors to the differential response. Blue whales exposed to simulated mid-frequency sonar in the Southern California Bight were less likely to produce low frequency calls usually associated with feeding behavior (Melcón et al., 2012). It is not known whether the lower rates of calling actually indicated a reduction in feeding behavior or social contact since the study used data from remotely deployed, passive acoustic monitoring buoys. In contrast, blue whales increased their likelihood of calling when ship noise was present, and decreased their likelihood of calling in the presence of explosive noise, although this result was not statistically significant (Melcón et al., 2012). Additionally, the likelihood of an animal calling decreased with the increased received level of mid-frequency sonar, beginning at a SPL of approximately 110-120 dB re 1 µPa (Melcón et al., 2012). Preliminary results from the 2010-2011 field season of an ongoing behavioral response study in Southern California waters indicated that, in some cases and at low received levels, tagged blue whales responded to mid-frequency sonar but that those responses were mild and there was a quick return to their baseline activity (Southall et al., 2011). A determination of whether foraging disruptions incur fitness consequences will require information on or estimates of the energetic requirements of the individuals and the relationship between prey availability, foraging effort and success, and the life history stage of the animal. Goldbogen et al., (2013) monitored behavioral responses of tagged blue whales located in feeding areas when exposed simulated MFA sonar

whether foraging disruptions incur fitness consequences will require information on or estimates of the energetic requirements of the individuals and the relationship between prey availability, foraging effort and success, and the life history stage of the animal. Goldbogen et al., (2013) monitored behavioral responses of tagged blue whales located in feeding areas when exposed simulated MFA sonar. Responses varied depending on behavioral context, with deep feeding whales being more significantly affected ( i.e., generalized avoidance; cessation of feeding; increased swimming speeds; or directed travel away from the source) compared to surface feeding individuals that typically showed no change in behavior. Non-feeding whales also seemed to be affected by exposure. The authors indicate that disruption of feeding and displacement could impact individual fitness and health.

Breathing —Variations in respiration naturally vary with different behaviors and variations in respiration rate as a function of acoustic exposure can be expected to co-occur with other behavioral reactions, such as a flight response or an alteration in diving. However, respiration rates in and of themselves may be representative of annoyance or an acute stress response. Mean exhalation rates of gray whales at rest and while diving were found to be unaffected by seismic surveys conducted adjacent to the whale feeding grounds (Gailey et al., 2007). Studies with captive harbor porpoises showed increased respiration rates upon introduction of acoustic alarms et al., 2001; Kastelein et al., 2006a) and emissions for underwater data transmission (Kastelein et al., 2005)

Mean exhalation rates of gray whales at rest and while diving were found to be unaffected by seismic surveys conducted adjacent to the whale feeding grounds (Gailey et al., 2007). Studies with captive harbor porpoises showed increased respiration rates upon introduction of acoustic alarms et al., 2001; Kastelein et al., 2006a) and emissions for underwater data transmission (Kastelein et al., 2005). However, exposure of the same acoustic alarm to a striped dolphin under the same conditions did not elicit a response (Kastelein et al., 2006a), again highlighting the importance in understanding species differences in the tolerance of underwater noise when determining the potential for impacts resulting from anthropogenic sound exposure (Southall et al., 2007; Henderson et al., 2014).

Social Relationships —Social interactions between mammals can be affected by noise via the disruption of communication signals or by the displacement of individuals. Disruption of social relationships therefore depends on the disruption of other behaviors ( e.g., caused avoidance, masking, etc.) and no specific overview is provided here. However, social disruptions must be considered in context of the relationships that are affected. Long-term disruptions of mother/calf pairs or mating displays have the potential to affect the growth and survival or reproductive effort/success of individuals, respectively.

Vocalizations (also see Masking Section)—Vocal changes in response to anthropogenic noise can occur across the repertoire of sound production modes used by marine mammals, such as whistling, echolocation click production, calling, and singing. Changes may result in response to a need to compete with an increase in background noise or may reflect an increased vigilance or startle response

tively.

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