Taking and Importing Marine Mammals; Taking Marine Mammals Incidental to the U.S. Navy Training and Testing Activities in the Northwest Training and Testing (NWTT) Study Area
Federal RegisterNov 12, 2020
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DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
50 CFR Part 218
[Docket No. 201020-0272]
RIN 0648-BJ30
Taking and Importing Marine Mammals; Taking Marine Mammals Incidental to the U.S. Navy Training and Testing Activities in the Northwest Training and Testing (NWTT) Study Area
AGENCY:
National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA), Commerce.
ACTION:
Final rule; notification of issuance of Letters of Authorization.
SUMMARY:
NMFS, upon request from the U.S. Navy (Navy), issues these regulations pursuant to the Marine Mammal Protection Act (MMPA) to govern the taking of marine mammals incidental to the training and testing activities conducted in the Northwest Training and Testing (NWTT) Study Area. The Navy's activities qualify as military readiness activities pursuant to the MMPA, as amended by the National Defense Authorization Act for Fiscal Year 2004 (2004 NDAA). These regulations, which allow for the issuance of Letters of Authorization (LOA) for the incidental take of marine mammals during the described activities and timeframes, prescribe the permissible methods of taking and other means of effecting the least practicable adverse impact on marine mammal species and their habitat, and establish requirements pertaining to the monitoring and reporting of such taking.
DATES:
Effective from November 9, 2020 to November 8, 2027.
ADDRESSES:
A copy of the Navy's application, NMFS' proposed and final rules and subsequent LOAs for the existing regulations, and other supporting documents and documents cited herein may be obtained online at:
www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-military-readiness-activities.
In case of problems accessing these documents, please use the contact listed here (see
FOR FURTHER INFORMATION CONTACT
).
FOR FURTHER INFORMATION CONTACT:
Leah Davis, Office of Protected Resources, NMFS, (301) 427-8401.
SUPPLEMENTARY INFORMATION:
Purpose of Regulatory Action
These regulations, issued under the authority of the MMPA (16 U.S.C. 1361
et seq.
), provide the framework for authorizing the take of marine mammals incidental to the Navy's training and testing activities (which qualify as military readiness activities) from the use of sonar and other transducers, in-water detonations, and potential vessel strikes based on Navy movement in the NWTT Study Area. The NWTT Study Area includes air and water space off the coast of Washington, Oregon, and Northern California; in the Western Behm Canal, Alaska; and portions of waters of the Strait of Juan de Fuca and Puget Sound, including Navy pierside and harbor locations in Puget Sound (see Figure 1-1 of the Navy's rulemaking/LOA application).
NMFS received an application from the Navy requesting seven-year regulations and authorizations to incidentally take individuals of multiple species of marine mammals (“Navy's rulemaking/LOA application” or “Navy's application”). Take is anticipated to occur by Level A harassment and Level B harassment as well as a very small number of serious injuries or mortalities incidental to the Navy's training and testing activities.
Section 101(a)(5)(A) of the MMPA (16 U.S.C. 1371(a)(5)(A)) directs the Secretary of Commerce (as delegated to NMFS) to allow, upon request, the incidental, but not intentional taking of small numbers of marine mammals by U.S. citizens who engage in a specified activity (other than commercial fishing) within a specified geographical region if, after notice and public comment, the agency makes certain findings and issues regulations that set forth permissible methods of taking pursuant to that activity, as well as monitoring and reporting requirements. Section 101(a)(5)(A) of the MMPA and the implementing regulations at 50 CFR part 216, subpart I, provide the legal basis for issuing this final rule and the subsequent LOAs. As directed by this legal authority, this final rule contains mitigation, monitoring, and reporting requirements.
Summary of Major Provisions Within the Final Rule
The following is a summary of the major provisions of this final rule regarding the Navy's activities. Major provisions include, but are not limited to:
• The use of defined powerdown and shutdown zones (based on activity);
• Measures to reduce the likelihood of ship strikes;
• Activity limitations in certain areas and times that are biologically important (
e.g.,
for foraging or migration) for marine mammals;
• Implementation of a Notification and Reporting Plan (for dead or live stranded marine mammals); and
• Implementation of a robust monitoring plan to improve our understanding of the environmental effects resulting from the Navy training and testing activities.
Additionally, the rule includes an adaptive management component that allows for timely modification of mitigation or monitoring measures based on new information, when appropriate.
Background
The MMPA prohibits the “take” of marine mammals, with certain exceptions. Sections 101(a)(5)(A) and (D) of the MMPA direct the Secretary of Commerce (as delegated to NMFS) to allow, upon request, the incidental, but not intentional, taking of small numbers of marine mammals by U.S. citizens who engage in a specified activity (other than commercial fishing) within a specified geographical region if certain findings are made and either regulations are issued or, if the taking is limited to harassment, a notice of proposed authorization is provided to the public for review and the opportunity to submit comments.
An authorization for incidental takings shall be granted if NMFS finds that the taking will have a negligible impact on the species or stocks and will not have an unmitigable adverse impact on the availability of the species or stocks for taking for subsistence uses (where relevant). Further, NMFS must prescribe the permissible methods of taking and other means of effecting the least practicable adverse impact on the affected species or stocks and their habitat, paying particular attention to rookeries, mating grounds, and areas of similar significance, and on the availability of the species or stocks for taking for certain subsistence uses (referred to in this rule as “mitigation measures”); and requirements pertaining to the monitoring and reporting of such takings. The MMPA defines “take” to mean to harass, hunt, capture, or kill, or attempt to harass, hunt, capture, or kill any marine mammal. The Analysis and Negligible Impact Determination section below discusses the definition of “negligible impact.”
The NDAA for Fiscal Year 2004 (2004 NDAA) (Pub. L. 108-136) amended section 101(a)(5) of the MMPA to remove the “small numbers” and
“specified geographical region” provisions indicated above and amended the definition of “harassment” as applied to a “military readiness activity.” The definition of harassment for military readiness activities (Section 3(18)(B) of the MMPA) is (i) Any act that injures or has the significant potential to injure a marine mammal or marine mammal stock in the wild (Level A Harassment); or (ii) Any act that disturbs or is likely to disturb a marine mammal or marine mammal stock in the wild by causing disruption of natural behavioral patterns, including, but not limited to, migration, surfacing, nursing, breeding, feeding, or sheltering, to a point where such behavioral patterns are abandoned or significantly altered (Level B harassment). In addition, the 2004 NDAA amended the MMPA as it relates to military readiness activities such that the least practicable adverse impact analysis shall include consideration of personnel safety, practicality of implementation, and impact on the effectiveness of the military readiness activity.
More recently, Section 316 of the NDAA for Fiscal Year 2019 (2019 NDAA) (Pub. L. 115-232), signed on August 13, 2018, amended the MMPA to allow incidental take rules for military readiness activities under section 101(a)(5)(A) to be issued for up to seven years. Prior to this amendment, all incidental take rules under section 101(a)(5)(A) were limited to five years.
Summary and Background of Request
On March 11, 2019, NMFS received an application from the Navy for authorization to take marine mammals by Level A harassment and Level B harassment incidental to training and testing activities (which qualify as military readiness activities) from the use of sonar and other transducers and in-water detonations in the NWTT Study Area over a seven-year period beginning when the 2015—2020 authorization expires. In addition, the Navy requested incidental take authorization by serious injury or mortality for up to three takes of large whales from vessel strikes over the seven-year period. We received revised applications on June 6, 2019 and June 21, 2019, which provided revisions in the take number estimates and vessel strike analysis, and the Navy's rulemaking/LOA application was found to be adequate and complete. On August 6, 2019 (84 FR 38225), we published a notice of receipt (NOR) of application in the
Federal Register
, requesting comments and information related to the Navy's request for 30 days. On October 4, 2019, the Navy submitted an amendment to its application which incorporated new Southern Resident killer whale offshore density information, and on December 19, 2019, the Navy submitted an amendment to its application which incorporated revised testing activity numbers. On June 2, 2020, we published a notice of proposed rulemaking (85 FR 33914) and requested comments and information related to the Navy's request for 45 days. All comments received during the NOR and the proposed rulemaking comment periods were considered in this final rule. Comments received on the proposed rule are addressed in this final rule in the Comments and Responses section.
The following types of training and testing, which are classified as military readiness activities pursuant to the MMPA, as amended by the 2004 NDAA, will be covered under the regulations and LOAs: Anti-submarine warfare (sonar and other transducers, underwater detonations), mine warfare (sonar and other transducers, underwater detonations), surface warfare (underwater detonations), and other testing and training (sonar and other transducers). The activities will not include pile driving/removal or use of air guns.
This would be the third time NMFS has promulgated incidental take regulations pursuant to the MMPA relating to similar military readiness activities in the NWTT Study Area. Specifically, five-year regulations addressing training in the Northwest Training Range Complex were first issued on November 9, 2010 (75 FR 69295; November 10, 2010) and five-year regulations addressing testing in the NUWC Keyport Range Complex were issued on April 11, 2011 (76 FR 20257; April 12, 2011). Regulations addressing both the training and testing activities from the two previous separate rules, Northwest Training and Testing (NWTT), were issued and were effective from November 9, 2015 through November 8, 2020 (80 FR 73555; November 24, 2015). For this third round of rulemaking, the activities the Navy is planning to conduct are largely a continuation of ongoing activities conducted over the past 10 years under the previous rulemakings, with the addition of some new training and testing activities, as well as additional mitigation measures.
The Navy's mission is to organize, train, equip, and maintain combat-ready naval forces capable of winning wars, deterring aggression, and maintaining freedom of the seas. This mission is mandated by Federal law (10 U.S.C. 8062), which requires the readiness of the naval forces of the United States. The Navy executes this responsibility in part by training and testing at sea, often in designated operating areas (OPAREA) and testing and training ranges. The Navy must be able to access and utilize these areas and associated sea space and air space in order to develop and maintain skills for conducting naval operations. The Navy's testing activities ensure naval forces are equipped with well-maintained systems that take advantage of the latest technological advances. The Navy's research and acquisition community conducts military readiness activities that involve testing. The Navy tests ships, aircraft, weapons, combat systems, sensors, and related equipment, and conducts scientific research activities to achieve and maintain military readiness.
The Navy has been conducting training and testing activities in the NWTT Study Area for decades, with some activities dating back to at least the early 1900s. The tempo and types of training and testing activities fluctuate because of the introduction of new technologies, the evolving nature of international events, advances in warfighting doctrine and procedures, and changes in force structure (
e.g.,
organization of ships, submarines, aircraft, weapons, and personnel). Such developments influence the frequency, duration, intensity, and location of required training and testing activities, however the Navy's planned activities for the period of this rule will be largely a continuation of ongoing activities. In addition to ongoing activities, the Navy is planning some new training activities such as torpedo exercise—submarine training and unmanned underwater vehicle training.
1
The Navy is also planning some new testing activities, including: At-sea sonar testing, Mine Countermeasure and Neutralization testing, mine detection and classification testing, kinetic energy weapon testing, propulsion testing, undersea warfare testing, vessel signature evaluation, acoustic and oceanographic research, radar and other system testing, and simulant testing.
2
1
Some of the activities included here are new to the 2020 NWTT FSEIS/OEIS, but are not new to the Study Area. TORPEX—SUB activity was previously analyzed in 2010 as part of the Sinking Exercise. The Sinking Exercise is no longer conducted in the NWTT Study Area and the TORPEX—SUB activity is now a separate activity included in the 2020 NWTT FSEIS/OEIS. Unmanned underwater vehicle activity was analyzed in 2010 as a testing activity, but is now being included as a training activity.
2
Mine detection and classification testing was analyzed in 2010 in the Inland waters, but was not previously analyzed in the Offshore waters. Vessel signature evaluation testing was analyzed in 2010
as a component to other activities, but is included in the list of new activities because it was not previously identified as an independent activity.
The Navy's rulemaking/LOA application reflects the most up-to-date compilation of training and testing activities deemed necessary to accomplish military readiness requirements. The types and numbers of activities included in the rule account for fluctuations in training and testing in order to meet evolving or emergent military readiness requirements. These regulations cover training and testing activities that will occur for a seven-year period following the expiration of the current MMPA authorization for the NWTT Study Area, which expires on November 8, 2020.
Description of the Specified Activity
A detailed description of the specified activity was provided in our
Federal Register
notice of proposed rulemaking (85 FR 33914; June 2, 2020); please see that notice of proposed rulemaking or the Navy's application for more information. Since publication of the proposed rule, the Navy has made some minor changes to its planned activities, all of which are in the form of reductions and thereby have the effect of reducing the impact of the activity. See the discussion of these changes below. In addition, since publication of the proposed rule, additional mitigation measures have been added, which are discussed in detail in the Mitigation Measures section of this rule. The Navy has determined that acoustic and explosive stressors are most likely to result in impacts on marine mammals that could rise to the level of harassment, and NMFS concurs with this determination. Additional detail regarding these activities is provided in Chapter 2 of the 2020 NWTT Final Supplemental Environmental Impact Statement (FSEIS)/Overseas EIS (OEIS) (2020 NWTT FSEIS/OEIS) (
https://www.nwtteis.com
) and in the Navy's rulemaking/LOA application (
https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-military-readiness-activities
) and are summarized here.
Dates and Duration
The specified activities can occur at any time during the seven-year period of validity of the regulations, with the exception of the activity types and time periods for which limitations have explicitly been identified (see Mitigation Measures section). The planned number of training and testing activities are described in the Detailed Description of the Specified Activities section (Tables 3 through 4).
Geographical Region
The NWTT 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, within Alaska state waters, and outside state waters of Oregon and Northern California (see Figure 1 in the proposed rule). The eastern boundary of the Offshore Area portion of the Study Area is 12 nautical miles (nmi) 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 that part of the Washington coast that lies beneath the airspace of W-237 and the Olympic Military Operations Area. The Study Area includes four existing range complexes and facilities: The Northwest Training Range Complex, the Keyport Range Complex, Carr Inlet Operations Area, and the Southeast Alaska Acoustic Measurement Facility (Western Behm Canal, Alaska). 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 Naval Base Kitsap, Bremerton; Naval Base Kitsap, Bangor; and Naval Station Everett. Additional detail can be found in Chapter 2 of the Navy's rulemaking/LOA application.
Overview of Training and Primary Mission Areas
The Navy categorizes its at-sea activities into functional warfare areas called primary mission areas. These activities generally fall into the following eight primary mission areas: Air warfare; amphibious warfare; anti-submarine warfare (ASW); electronic warfare; expeditionary warfare; mine warfare (MIW); strike warfare; and surface warfare (SUW). The Navy's planned activities for NWTT generally fall into the following six primary mission areas: Air warfare; anti-submarine warfare; electronic warfare; expeditionary warfare; mine warfare; and surface warfare. Most activities addressed in the NWTT Study Area are categorized under one of these primary mission areas. Activities that do not fall within one of these areas are listed as “other activities.” Each warfare community (surface, subsurface, aviation, and expeditionary warfare) may train in some or all of these primary mission areas. The testing community also categorizes most, but not all, of its testing activities under these primary mission areas. A description of the sonar, munitions, targets, systems, and other material used during training and testing activities within these primary mission areas is provided in Appendix A (
Navy Activities Descriptions
) of the 2020 NWTT FSEIS/OEIS.
The Navy describes and analyzes the effects of its activities within the 2020 NWTT FSEIS/OEIS. In its assessment, the Navy concluded that sonar and other transducers and in-water detonations were the stressors most likely to result in impacts on marine mammals that could rise to the level of harassment as defined under the MMPA. Therefore, the Navy's rulemaking/LOA application provides the Navy's assessment of potential effects from these stressors in terms of the various warfare mission areas in which they would be conducted. Those mission areas include the following:
• Anti-submarine warfare (sonar and other transducers, underwater detonations);
• expeditionary warfare;
• mine warfare (sonar and other transducers, underwater detonations);
• surface warfare (underwater detonations); and
• other (sonar and other transducers).
The Navy's training and testing activities in air warfare and electronic warfare do not involve sonar and other transducers, underwater detonations, or any other stressors that could result in harassment, serious injury, or mortality of marine mammals. Therefore, the activities in air warfare and electronic warfare are not discussed further in this rule, but are analyzed fully in the 2020 NWTT FSEIS/OEIS. Additional detail regarding the primary mission areas was provided in our
Federal Register
notice of proposed rulemaking (85 FR 33914; June 2, 2020); please see that notice of proposed rulemaking or the Navy's application for more information.
Overview of Testing Activities Within the NWTT Study Area
The Navy's research and acquisition community engages in a broad spectrum of testing activities in support of the Fleet. These activities include, but are not limited to, basic and applied scientific research and technology development; testing, evaluation, and maintenance of systems (missiles, radar, and sonar) and platforms (surface ships, submarines, and aircraft); and acquisition of systems and platforms.
The individual commands within the research and acquisition community include Naval Air Systems Command, Naval Sea Systems Command, and Office of Naval Research.
Description of Stressors
The Navy uses a variety of sensors, platforms, weapons, and other devices, including ones used to ensure the safety of Sailors and Marines, to meet its mission. Training and testing with these systems may introduce acoustic (sound) energy or shock waves from explosives into the environment. The following subsections describe the acoustic and explosive stressors for marine mammals and their habitat (including prey species) within the NWTT Study Area. Because of the complexity of analyzing sound propagation in the ocean environment, the Navy relied on acoustic models in its environmental analyses and rulemaking/LOA application that considered sound source characteristics and varying ocean conditions across the NWTT Study Area. Stressor/resource interactions that were determined to have de minimis or no impacts (
e.g.,
vessel noise, aircraft noise, weapons noise, and explosions in air) were not carried forward for analysis in the Navy's rulemaking/LOA application. No Major Training Exercises (MTEs) or Sinking Exercise (SINKEX) events are planned in the NWTT Study Area. NMFS reviewed the Navy's analysis and conclusions on de minimis sources and finds them complete and supportable.
Acoustic stressors include acoustic signals emitted into the water for a specific purpose, such as sonar, other transducers (devices that convert energy from one form to another—in this case, into sound waves), as well as incidental sources of broadband sound produced as a byproduct of vessel movement, aircraft transits, and use of weapons or other deployed objects. Explosives also produce broadband sound but are characterized separately from other acoustic sources due to their unique hazardous characteristics. Characteristics of each of these sound sources are described in the following sections.
In order to better organize and facilitate the analysis of approximately 300 sources of underwater sound used for training and testing by the Navy, including sonar and other transducers and explosives, a series of source classifications, or source bins, were developed. The source classification bins do not include the broadband sounds produced incidental to vessel and aircraft transits and weapons firing. Noise produced from vessel, aircraft, and weapons firing activities are not carried forward because those activities were found to have de minimis or no impacts, as stated above.
The use of source classification bins provides the following benefits:
• Provides the ability for new sensors or munitions to be covered under existing authorizations, as long as those sources fall within the parameters of a “bin;”
• Improves efficiency of source utilization data collection and reporting requirements anticipated under the MMPA authorizations;
• Ensures a conservative approach to all impact estimates, as all sources within a given class are modeled as the most impactful source (highest source level, longest duty cycle, or largest net explosive weight) within that bin;
• Allows analyses to be conducted in a more efficient manner, without any compromise of analytical results; and
• Provides a framework to support the reallocation of source usage (hours/explosives) between different source bins, as long as the total numbers of takes remain within the overall analyzed and authorized limits. This flexibility is required to support evolving Navy training and testing requirements, which are linked to real world events.
Sonar and Other Transducers
Active sonar and other transducers emit non-impulsive sound waves into the water to detect objects, navigate safely, and communicate. Passive sonars differ from active sound sources in that they do not emit acoustic signals; rather, they only receive acoustic information about the environment, or listen. In this rule, the terms sonar and other transducers will be used to indicate active sound sources unless otherwise specified.
The Navy employs a variety of sonars and other transducers to obtain and transmit information about the undersea environment. Some examples are mid-frequency hull-mounted sonars used to find and track enemy submarines; high-frequency small object detection sonars used to detect mines; high-frequency underwater modems used to transfer data over short ranges; and extremely high-frequency (greater than 200 kilohertz (kHz)) Doppler sonars used for navigation, like those used on commercial and private vessels. The characteristics of these sonars and other transducers, such as source level, beam width, directivity, and frequency, depend on the purpose of the source. Higher frequencies can carry more information or provide more information about objects off which they reflect, but attenuate more rapidly. Lower frequencies attenuate less rapidly, so they may detect objects over a longer distance, but with less detail.
Additional detail regarding sound sources and platforms and categories of acoustic stressors was provided in our
Federal Register
notice of proposed rulemaking (85 FR 33914; June 2, 2020); please see that notice of proposed rulemaking or the Navy's application for more information.
Sonars and other transducers are grouped into classes that share an attribute, such as frequency range or purpose of use. As detailed below, classes are further sorted by bins based on the frequency or bandwidth; source level; and, when warranted, the application in which the source would be used. Unless stated otherwise, a reference distance of 1 meter (m) is used for sonar and other transducers.
• Frequency of the non-impulsive acoustic source:
○ Low-frequency sources operate below 1 kHz;
○ Mid-frequency sources operate at and above 1 kHz, up to and including 10 kHz;
○ High-frequency sources operate above 10 kHz, up to and including 100 kHz;
○ Very-high-frequency sources operate above 100 kHz but below 200 kHz;
• Sound pressure level of the non-impulsive source;
○ Greater than 160 decibels (dB) re 1 micro Pascal (µPa), but less than 180 dB re: 1 µPa;
○ Equal to 180 dB re: 1 µPa and up to 200 dB re: 1 µPa;
○ Greater than 200 dB re: 1 µPa;
• Application in which the source would be used:
○ Sources with similar functions that have similar characteristics, such as pulse length (duration of each pulse), beam pattern, and duty cycle.
The bins used for classifying active sonars and transducers that are quantitatively analyzed in the NWTT Study Area are shown in Table 1 below. While general parameters or source characteristics are shown in the table, actual source parameters are classified.
Table 1—Sonar and Other Transducers Quantitatively Analyzed in the NWTT Study Area
Source class category
Bin
Description
Low-Frequency (LF): Sources that produce signals less than 1 kHz
LF4
LF5
LF sources equal to 180 dB and up to 200 dB.
LF sources less than 180 dB.
Mid-Frequency (MF): Tactical and non-tactical sources that produce signals between 1 and 10 kHz
MF1
Hull-mounted surface ship sonars (
e.g.,
AN/SQS-53C and AN/SQS-60).
MF1K
Kingfisher mode associated with MF1 sonars.
MF2
Hull-mounted surface ship sonars (
e.g.,
AN/SQS-56).
MF3
Hull-mounted submarine sonars (
e.g.,
AN/BQQ-10).
MF4
Helicopter-deployed dipping sonars (
e.g.,
AN/AQS-22).
MF5
Active acoustic sonobuoys (
e.g.,
DICASS).
MF6
Underwater sound signal devices (
e.g.,
MK 84 SUS).
MF9
Sources (equal to 180 dB and up to 200 dB) not otherwise binned.
MF10
Active sources (greater than 160 dB, but less than 180 dB) not otherwise binned.
MF11
Hull-mounted surface ship sonars with an active duty cycle greater than 80 percent.
MF12
Towed array surface ship sonars with an active duty cycle greater than 80 percent.
High-Frequency (HF): Tactical and non-tactical sources that produce signals between 10 and 100 kHz
HF1
HF3
Hull-mounted submarine sonars (
e.g.,
AN/BQQ-10).
Other hull-mounted submarine sonars (classified).
HF4
Mine detection, classification, and neutralization sonar (
e.g.,
AN/SQS-20).
HF5
Active sources (greater than 200 dB) not otherwise binned.
HF6
Sources (equal to 180 dB and up to 200 dB) not otherwise binned.
HF8
Hull-mounted surface ship sonars (
e.g.,
AN/SQS-61).
HF9
Weapon-emulating sonar source.
Very High-Frequency (VHF): Tactical and non-tactical sources that produce signals greater than 100 kHz but less than 200 kHz
VHF1
VHF2
Active sources greater than 200 dB.
Active sources with a source level less than 200 dB.
Anti-Submarine Warfare (ASW): Tactical sources (
e.g.,
active sonobuoys and acoustic countermeasures systems) used during ASW training and testing activities
ASW1
ASW2
ASW3
ASW4
ASW5
1
MF systems operating above 200 dB.
MF Multistatic Active Coherent sonobuoy (
e.g.,
AN/SSQ-125).
MF towed active acoustic countermeasure systems (
e.g.,
AN/SLQ-25).
MF expendable active acoustic device countermeasures (
e.g.,
MK 3).
MF sonobuoys with high duty cycles.
Torpedoes (TORP): Active acoustic signals produced by torpedoes
TORP1
Lightweight torpedo (
e.g.,
MK 46, MK 54, or Anti-Torpedo Torpedo).
TORP2
Heavyweight torpedo (
e.g.,
MK 48).
TORP3
Heavyweight torpedo (
e.g.,
MK 48).
Looking Sonar (FLS): Forward or upward looking object avoidance sonars used for ship navigation and safety
FLS2
HF sources with short pulse lengths, narrow beam widths, and focused beam patterns.
Acoustic Modems (M): Sources used to transmit data
M3
MF acoustic modems (greater than 190 dB).
Synthetic Aperture Sonars (SAS): Sonars used to form high-resolution images of the seafloor
SAS2
HF SAS systems.
Broadband Sound Sources (BB): Sonar systems with large frequency spectra, used for various purposes
BB1
BB2
MF to HF mine countermeasure sonar.
HF to VHF mine countermeasure sonar.
1
Formerly ASW2 in the 2015-2020 (Phase II) rulemaking.
Explosives
This section describes the characteristics of explosions during naval training and testing. The activities analyzed in the Navy's rulemaking/LOA application that use explosives are described in additional detail in Appendix A (
Training and Testing Activities Descriptions
) of the 2020 NWTT FSEIS/OEIS. Explanations of the terminology and metrics used when describing explosives in the Navy's rule making/LOA application are also in Appendix H (
Acoustic and Explosive Concepts
) of the 2020 NWTT FSEIS/OEIS.
The near-instantaneous rise from ambient to an extremely high peak pressure is what makes an explosive shock wave potentially damaging. Farther from an explosive, the peak pressures decay and the explosive waves propagate as an impulsive, broadband sound. Several parameters influence the effect of an explosive: The weight of the explosive in the warhead, the type of explosive material, the boundaries and characteristics of the propagation medium, and, in water, the detonation depth and the depth of the receiver (
i.e.,
marine mammal). The net explosive weight, which is the explosive power of a charge expressed as the equivalent weight of trinitrotoluene (TNT), accounts for the first two parameters. The effects of these factors are explained in Appendix D (
Acoustic and Explosive Concepts
) of the 2020 NWTT FSEIS/OEIS. The activities analyzed in the Navy's rulemaking/LOA application and this final rule that use explosives are described in further detail in Appendix A (
Navy Activities Descriptions
) of the 2020 NWTT FSEIS/OEIS. Explanations of the terminology and metrics used when describing explosives are provided in Appendix D (
Acoustic and Explosive Concepts
) of the 2020 NWTT FSEIS/OEIS.
Explosive detonations during training and testing activities are associated with high-explosive munitions, including,
but not limited to, bombs, missiles, naval gun shells, torpedoes, mines, demolition charges, and explosive sonobuoys. Explosive detonations during training and testing involving the use of high-explosive munitions (including bombs, missiles, and naval gun shells) could occur in the air or near the water's surface. Explosive detonations associated with torpedoes and explosive sonobuoys would occur in the water column; mines and demolition charges could be detonated in the water column or on the ocean bottom. Most detonations will occur in waters greater than 200 ft in depth, and greater than 50 nmi from shore, with the exception of Mine Countermeasure and Neutralization testing planned in the Offshore Area, and existing mine warfare training areas in Inland Waters (
i.e.,
Crescent Harbor and Hood Canal Explosive Ordnance Disposal Training Ranges). Mine countermeasure and neutralization testing is a new planned testing activity that would occur closer to shore than other in-water explosive activities analyzed in the 2015 NWTT Final EIS/OEIS for the Offshore Area of the NWTT Study Area. This activity would occur in waters 3 nmi or greater from shore in the Quinault Range Site (outside the Olympic Coast National Marine Sanctuary), or 12 nmi or greater from shore elsewhere in the Offshore Area, and will not occur off the coast of California. Since publication of the proposed rule, the Navy has agreed that it will conduct explosive Mine Countermeasure and Neutralization testing in daylight hours only, and in Beaufort Sea state number 3 conditions or less. Two of the three events would involve the use of explosives, and would typically occur in water depths shallower than 1,000 ft. The two multi-day events (1-10 days per event) would include up to 36 E4 explosives (>2.5-5 lb net explosive weight) and 5 E7 explosives (>20-60 lb net explosive weight). Use of E7 explosives would occur greater than 6 nmi from shore. Since publication of the proposed rule, the Navy has agreed that, within 20 nmi from shore in the Marine Species Coastal Mitigation Area, the Navy will conduct no more than one Mine Countermeasure and Neutralization testing event annually, not to exceed the use of 20 E4 and 3 E7 explosives, from October 1 through June 30. Additionally, within 20 nmi from shore in the Marine Species Coastal Mitigation Area, the Navy will not exceed 60 E4 and 9 E7 explosives over seven years, from October 1 through June 30. Finally, to the maximum extent practical, the Navy will conduct explosive Mine Countermeasure and Neutralization Testing from July 1 through September 30 when operating within 20 nmi from shore in the Marine Species Coastal Mitigation Area. In order to better organize and facilitate the analysis of explosives used by the Navy during training and testing that could detonate in water or at the water surface, explosive classification bins were developed. The use of explosive classification bins provides the same benefits as described for acoustic source classification bins discussed above and in Section 1.4.1 (Acoustic Stressors) of the Navy's rulemaking/LOA application.
Explosives detonated in water are binned by net explosive weight. The bins of explosives in the NWTT Study Area are shown in Table 2 below.
Table 2—Explosives Analyzed in the NWTT Study Area
Bin
Net explosive weight
(lb)
Example explosive source
E1
0.1-0.25
Medium-caliber projectiles.
E2
>0.25-0.5
Medium-caliber projectiles.
E3
>0.5-2.5
Explosive Ordnance Disposal Mine Neutralization.
E4
>2.5-5
Mine Countermeasure and Neutralization.
E5
>5-10
Large-caliber projectile.
E7
>20-60
Mine Countermeasure and Neutralization.
E8
>60-100
Lightweight torpedo.
E10
>250-500
1,000 lb bomb.
E11
>500-650
Heavyweight torpedo.
Propagation of explosive pressure waves in water is highly dependent on environmental characteristics such as bathymetry, bottom type, water depth, temperature, and salinity, which affect how the pressure waves are reflected, refracted, or scattered; the potential for reverberation; and interference due to multi-path propagation. In addition, absorption greatly affects the distance over which higher-frequency components of explosive broadband noise can propagate. Appendix D (
Acoustic and Explosive Concepts
) of the 2020 NWTT FSEIS/OEIS explains the characteristics of explosive detonations and how the above factors affect the propagation of explosive energy in the water.
Marine mammals could be exposed to fragments from underwater explosions associated with the specified activities. When explosive ordnance
(e.g.,
bomb or missile) detonates, fragments of the weapon are thrown at high-velocity from the detonation point, which can injure or kill marine mammals if they are struck. These fragments may be of variable size and are ejected at supersonic speed from the detonation. The casing fragments will be ejected at velocities much greater than debris from any target due to the proximity of the casing to the explosive material. Risk of fragment injury reduces exponentially with distance as the fragment density is reduced. Fragments underwater tend to be larger than fragments produced by in-air explosions (Swisdak and Montaro, 1992). Underwater, the friction of the water would quickly slow these fragments to a point where they no longer pose a threat. Opposingly, the blast wave from an explosive detonation moves efficiently through the seawater. Because the ranges to mortality and injury due to exposure to the blast wave are likely to far exceed the zone where fragments could injure or kill an animal, the thresholds and associated ranges for assessing the likelihood of mortality and injury from a blast, which are also used to inform mitigation zones, are assumed to encompass risk due to fragmentation.
Other Stressor—Vessel Strike
Vessel strikes are not specific to any particular training or testing activity, but rather a potential, limited, sporadic, and incidental result of Navy vessel movement within the NWTT Study Area. Navy vessels transit at speeds that are optimal for fuel conservation or to meet training and testing requirements. Should a vessel strike occur, it would likely result in incidental take from
serious injury and/or mortality and, accordingly, for the purposes of the analysis we assume that any authorized ship strike would result in serious injury or mortality. Information on Navy vessel movement is provided in the
Vessel Movement
section of this rule. Additional detail on vessel strike was provided in our
Federal Register
notice of proposed rulemaking (85 FR 33914; June 2, 2020); please see that notice of proposed rulemaking or the Navy's application for more information.
Detailed Description of Specified Activities
Planned Training and Testing Activities
The Navy's Operational Commands and various System Commands have identified activity levels that are needed in the NWTT Study Area to ensure naval forces have sufficient training, maintenance, and new technology to meet Navy missions in the Northwest. Training prepares Navy personnel to be proficient in safely operating and maintaining equipment, weapons, and systems to conduct assigned missions. Navy research develops new science and technology followed by concept testing relevant to future Navy needs.
The training and testing activities that the Navy plans to conduct in the NWTT Study Area are summarized in Table 3 (training) and Table 4 (testing). The tables are organized according to primary mission areas and include the activity name, associated stressor(s), description of the activity, sound source bin, the locations of those activities in the NWTT Study Area, and the number of activities. For further information regarding the primary platform used (
e.g.,
ship or aircraft type) see Appendix A (
Training and Testing Activities Descriptions
) of the 2020 NWTT FSEIS/OEIS.
This section indicates the number of activities that could occur each year and then the maximum total that could occur over seven years. When a range of annual activities is provided, the maximum number is analyzed. The maximum number of activities may occur during some years, but not others, as several activities—Torpedo Exercise-Submarine Training, Tracking Exercise- Helicopter Training, Civilian Port Defense- Homeland Security Anti-Terrorism/Force Protection Training, Bomb Exercise Training, and Missile Exercise Training—do not occur every year, and other activities may occur every year, but less frequently than the maximum annual total. However, to conduct a conservative analysis, NMFS analyzed the maximum times these activities could occur over one year and seven years, with the assumption that this number of activities would be representative of the annual and seven-year activity totals.
Table 3—Training Activities Analyzed for the Seven-Year Period in the NWTT Study Area
Stressor category
Activity
Description
Typical
duration of event
Source bin
Location
Annual number of events
7-Year number of events
Anti-Submarine Warfare
Acoustic; Explosive
Torpedo Exercise—Submarine (TORPEX—Sub)
Submarine crews search for, track, and detect submarines. Event would include one MK-48 torpedo used during this event
8 hours
TORP2
Offshore Area >12 nmi from land
0-2
5
Acoustic
Tracking Exercise -Helicopter (TRACKEX—Helo)
Helicopter crews search for, track, and detect submarines
2-4 hours
MF4, MF5
Offshore Area >12 nmi from land
0-2
5
Acoustic
Tracking Exercise—Maritime Patrol Aircraft (TRACKEX—MPA)
Maritime patrol aircraft crews search for, track, and detect submarines
2-8 hours
ASW2, ASW5, MF5, TORP1
Offshore Area >12 nmi from land
373
2,611
Acoustic
Tracking Exercise -Ship (TRACKEX—Ship)
Surface ship crews search for, track, and detect submarines
2-4 hours
ASW3, MF1, MF11
Offshore Area
62
434
Acoustic
Tracking Exercise—Submarine (TRACKEX—Sub)
Submarine crews search for, track, and detect submarines
8 hours
HF1, MF3
Offshore Area
75-100
595
Mine Warfare
Acoustic
Civilian Port Defense—Homeland Security Anti-Terrorism/Force Protection Exercises
Maritime security personnel train to protect civilian ports and harbors against enemy efforts to interfere with access to those ports.
Multiple days
HF4, SAS2
Inland Waters
0-1
5
Explosive
Mine Neutralization—Explosive Ordnance Disposal (EOD)
Personnel disable threat mines using explosive charges
Up to 4 hours
E3
Crescent Harbor EOD Training Range, Hood Canal EOD Training Range
1
6
1
42
Surface Warfare
Explosive
Bombing Exercise (Air-to-Surface)(BOMBEX [A-S])
Fixed-wing aircrews deliver bombs against surface targets
1 hour
E10
Offshore Area (W-237) > 50 nmi from land
0-2 (counts only the explosive events)
5
Explosive
Gunnery Exercise (Surface-to-Surface)—Ship (GUNEX [S-S]—Ship)
Surface ship crews fire large- and medium-caliber guns at surface targets.
Up to 3 hours
E1, E2, E5
Offshore Area > 50 nmi from land
1
34 (counts only the explosive events)
1
238
Explosive
Missile Exercise (Air-to-Surface)(MISSILEX [A-S])
Fixed-wing aircrews simulate firing precision-guided missiles, using captive air training missiles (CATMs) against surface targets. Some activities include firing a missile with a high-explosive (HE) warhead.
2 hours
E10
Offshore Area (W-237) > 50 nmi from land
0-2
5
Other Training
Acoustic
Submarine Sonar Maintenance
Maintenance of submarine sonar and other system checks are conducted pierside or at sea.
Up to 1 hour
LF5, MF3, HF1
NBK Bangor, NBK Bremerton, and Offshore Area >12 nmi from land
26
182
Acoustic
Surface Ship Sonar Maintenance
Maintenance of surface ship sonar and other system checks are conducted pierside or at sea.
Up to 4 hours
MF1
NBK Bremerton, NS Everett, and Offshore Area >12 nmi from land
25
175
Acoustic
Unmanned Underwater Vehicle Training
Unmanned underwater vehicle certification involves training with unmanned platforms to ensure submarine crew proficiency. Tactical development involves training with various payloads for multiple purposes to ensure that the systems can be employed effectively in an operational environment.
Up to 24 hours
FLS2, M3
Inland Waters, Offshore Area
60
420
1
These activities have been reduced since publication of the proposed rule.
Table 4—Testing Activities Analyzed for the Seven-Year Period in the NWTT Study Area
Stressor category
Activity
Description
Typical
duration
Source bin
Location
Annual number of events
7-Year number of events
Naval Sea Systems Command Testing Activities
Anti-Submarine Warfare
Acoustic
Anti-Submarine Warfare Testing
Ships and their supporting platforms (rotary-wing aircraft and unmanned aerial systems) detect, localize, and prosecute submarines
4-8 hours of active sonar use
ASW1, ASW2, ASW3, ASW5, MF1K, MF4, MF5, MF10, MF11, MF12, TORP1
Offshore Area
44
308
Acoustic
At-Sea Sonar Testing
At-sea testing to ensure systems are fully functional in an open ocean environment.
From 4 hours to 11 days
ASW3, HF1, HF5, M3, MF3,
ASW3, HF5, TORP1
Offshore Area
Inland Waters (DBRC)
4
4-6
28
34
Acoustic
Countermeasure Testing
Countermeasure testing involves the testing of systems that will detect, localize, and track incoming weapons, including marine vessel targets. Countermeasures may be systems to obscure the vessel's location or systems to rapidly detect, track, and counter incoming threats. Testing includes surface ship torpedo defense systems and marine vessel stopping payloads
From 4 hours to 6 days
ASW3, ASW4, HF8, MF1, TORP2
ASW3, ASW4
ASW4
Offshore Area (QRS)
Inland Waters (DBRC, Keyport Range Site)
Western Behm Canal, AK
14
29
1
98
203
5
Acoustic
Pierside-Sonar Testing
Pierside testing to ensure systems are fully functional in a controlled pierside environment prior to at-sea test activities
Up to 3 weeks
ASW3, HF3, MF1, MF2, MF3, MF9, MF10, MF12
Inland Waters (NS Everett, NBK Bangor, NBK Bremerton)
88-99
635
Acoustic
Submarine Sonar Testing/Maintenance
Pierside, moored, and underway testing of submarine systems occurs periodically following major maintenance periods and for routine maintenance
Up to 3 weeks
HF6, MF9
Western Behm Canal, AK
1-2
10
Acoustic; Explosive
Torpedo (Explosive) Testing
Air, surface, or submarine crews employ explosive and non-explosive torpedoes against artificial targets
1-2 hours during daylight only
E8, E11, ASW3, HF1, HF6, MF1, MF3, MF4, MF5, MF6, TORP1, TORP2
Offshore Area> 50 nmi from land
4
28
Acoustic
Torpedo (Non-explosive) Testing
Air, surface, or submarine crews employ non-explosive torpedoes against targets, submarines, or surface vessels.
Up to 2 weeks
ASW3, ASW4, HF1, HF5, HF6, MF1, MF3, MF4, MF5, MF6, MF9, MF10, TORP1, TORP2
HF6, LF4, TORP1, TORP2, TORP3
Offshore Area
Inland Waters (DBRC)
22
61
154
427
Mine Warfare
Acoustic; Explosive
Mine Countermeasure and Neutralization Testing
Air, surface, and subsurface vessels neutralize threat mines and mine-like objects.
1-10 days
E4, E7, HF4
HF4
Offshore Area
Inland Waters
1
2
3
1
6
13
Acoustic
Mine Detection and Classification Testing
Air, surface, and subsurface vessels and systems detect and classify mines and mine-like objects. Vessels also assess their potential susceptibility to mines and mine-like objects.
Up to 24 days
BB1, BB2, LF4
BB1, BB2, HF4, LF4
Offshore Area (QRS)
Inland Waters (DBRC, Keyport Range Site)
1
42
7
294
Unmanned Systems
Acoustic
Unmanned Underwater Vehicle Testing
Testing involves the production or upgrade of unmanned underwater vehicles. This may include testing of mission capabilities (
e.g.,
mine detection), evaluating the basic functions of individual platforms, or conducting complex events with multiple vehicles.
Typically 1-2 days, up to multiple months
FLS2, HF5, TORP1, VHF1
DS3, FLS2, HF5, HF9, M3, SAS2, VHF1, TORP1
Offshore Area (QRS)
Inland Waters (DBRC, Keyport Range Site, Carr Inlet)
38-39
371-379
269
2,615
Vessel Evaluation
Acoustic
Undersea Warfare Testing
Ships demonstrate capability of countermeasure systems and underwater surveillance, weapons engagement, and communications systems. This tests ships' ability to detect, track, and engage undersea targets.
Up to 10 days
ASW3, ASW4, HF4, MF1, MF4, MF5, MF6, MF9, TORP1, TORP2
Offshore Area
1-12
27
Other Testing
Acoustic
Acoustic and Oceanographic Research
Research using active transmissions from sources deployed from ships, aircraft, and unmanned underwater vehicles. Research sources can be used as proxies for current and future Navy systems.
Up to 14 days
LF4, MF9
Offshore Area (QRS)
Inland Waters (DBRC, Keyport Range Site)
1
3
7
21
Acoustic
Acoustic Component Testing
Various surface vessels, moored equipment, and materials are tested to evaluate performance in the marine environment
1 day to multiple months
HF3, HF6, LF5, MF9
Western Behm Canal, AK
13-18
99
Acoustic
Cold Water Support
Fleet training for divers in a cold water environment, and other diver training related to Navy divers supporting range/test site operations and maintenance.
8 hours
HF6
Inland Waters (Keyport Range Site, DBRC, Carr Inlet)
Western Behm Canal, AK
4
1
28
7
Acoustic
Post-Refit Sea Trial
Following periodic maintenance periods or repairs, sea trials are conducted to evaluate submarine propulsion, sonar systems, and other mechanical tests.
8 hours
HF9, M3, MF10
Inland Waters (DBRC)
30
210
Acoustic
Semi-Stationary Equipment Testing
Semi-stationary equipment (
e.g.,
hydrophones) is deployed to determine functionality.
From 10 minutes to multiple days
HF6, HF9, LF4, MF9, VHF2
HF6, HF9
Inland Waters (DBRC, Keyport Range Site)
Western Behm Canal, AK
120
2-3
840
12
Naval Air Systems Command Testing Activities
Anti-Submarine Warfare
Acoustic; Explosive
Tracking Test—Maritime Patrol Aircraft
The test evaluates the sensors and systems used by maritime patrol aircraft to detect and track submarines and to ensure that aircraft systems used to deploy the tracking systems perform to specifications and meet operational requirements.
4-8 flight hours
E1, E3, ASW2, ASW5, MF5, MF6
Offshore Area
8
56
1
In the proposed rule, NMFS analyzed three events annually, and 15 events over the seven-year period; however, only two of the three annual events include sonar and/or explosives. The third annual event does not have acoustic components, and therefore, is not included here in the final rule. Additionally, the seven-year number of events has been reduced since publication of the proposed rule.
Summary of Acoustic and Explosive Sources Analyzed for Training and Testing
Tables 5 through 8 show the acoustic and explosive source classes, bins, and quantities used in either hours or counts associated with the Navy's training and testing activities over a seven-year period in the NWTT Study Area that were analyzed in the Navy's rulemaking/LOA application and by NMFS through the rulemaking process. Table 5 describes the acoustic source classes (
i.e.,
low-frequency (LF), mid-frequency (MF), and high-frequency (HF)) that could occur over seven years under the planned training activities. Acoustic source bin use in the proposed activities will vary annually. The seven-year totals for the planned training activities take into account that annual variability.
Table 5—Acoustic Source Classes Analyzed and Usage for Seven-Year Period for Training Activities in the NWTT Study Area
Source class category
Bin
Description
Unit
1
Annual
7-year total
Low-Frequency (LF): Sources that produce signals less than 1 kHz
LF5
LF sources less than 180 dB
H
1
5
Mid-Frequency (MF): Tactical and non-tactical sources that produce signals between 1 and 10 kHz
MF1
Hull-mounted surface ship sonars (
e.g.,
AN/SQS-53C and AN/SQS-61)
H
164
1,148
MF3
Hull-mounted submarine sonars (
e.g.,
AN/BQQ-10)
H
70
490
MF4
Helicopter-deployed dipping sonars (
e.g.,
AN/AQS-22 and AN/AQS-13)
H
0-1
1
MF5
Active acoustic sonobuoys (
e.g.,
DICASS)
C
918-926
6,443
MF11
Hull-mounted surface ship sonars with an active duty cycle greater than 80%
H
16
112
High-Frequency (HF): Tactical and non-tactical sources that produce signals between 10 and 100 kHz
HF1
Hull-mounted submarine sonars (
e.g.,
AN/BQQ-10)
H
48
336
HF4
Mine detection, classification, and neutralization sonar (
e.g.,
AN/SQS-20)
H
0-65
269
Anti-Submarine Warfare (ASW): Tactical sources (
e.g.,
active sonobuoys and acoustic countermeasures systems) used during ASW training and testing activities
ASW2
MF Multistatic Active Coherent sonobuoy (
e.g.,
AN/SSQ-125)
C
350
2,450
ASW3
MF towed active acoustic countermeasure systems (
e.g.,
AN/SLQ-25)
H
86
602
ASW5
MF sonobuoys with high duty cycles
H
50
350
Torpedoes (TORP): Source classes associated with the active acoustic signals produced by torpedoes
TORP1
Lightweight torpedo (
e.g.,
MK 46, MK 54, or Anti-Torpedo Torpedo)
C
16
112
TORP2
Heavyweight torpedo (
e.g.,
MK 48)
C
0-2
5
Forward Looking Sonar (FLS): Forward or upward looking object avoidance sonars used for ship navigation and safety
FLS2
HF sources with short pulse lengths, narrow beam widths, and focused beam patterns
H
240
1,680
Acoustic Modems (M): Systems used to transmit data through the water
M3
MF acoustic modems (greater than 190 dB)
H
30
210
Synthetic Aperture Sonars (SAS): Sonars in which active acoustic signals are post-processed to form high-resolution images of the seafloor
SAS2
HF SAS systems
H
0-561
2,353
1
H = hours; C = count.
Table 6 describes the acoustic source classes and numbers that could occur over seven years under the planned testing activities. Acoustic source bin use in the planned activities would vary annually. The seven-year totals for the planned testing activities take into account that annual variability.
Table 6—Acoustic Source Classes Analyzed and Usage for Seven-Year Period for Testing Activities in the NWTT Study Area
Source class category
Bin
Description
Unit
1
Annual
7-year total
Low-Frequency (LF): Sources that produce signals less than 1 kHz
LF4
LF sources equal to 180 dB and up to 200 dB
H
177
1,239
LF5
LF sources less than 180 dB
H
0-18
23
Mid-Frequency (MF): Tactical and non-tactical sources that produce signals between 1 and 10 kHz
MF1
Hull-mounted surface ship sonars (
e.g.,
AN/SQS-53C and AN/SQS-61)
H
20-169
398
MF1K
Kingfisher mode associated with MF1 sonars
H
48
336
MF2
Hull-mounted surface ship sonars (
e.g.,
AN/SQS-56)
H
32
224
MF3
Hull-mounted submarine sonars (
e.g.,
AN/BQQ-10)
H
34-36
239
MF4
Helicopter-deployed dipping sonars (
e.g.,
AN/AQS-22 and AN/AQS-13)
H
41-50
298
MF5
Active acoustic sonobuoys (
e.g.,
DICASS)
C
300-673
2,782
MF6
Active underwater sound signal devices (
e.g.,
MK 84 SUS)
C
60-232
744
MF9
Active sources (equal to 180 dB and up to 200 dB) not otherwise binned
H
644-959
5,086
MF10
Active sources (greater than 160 dB, but less than 180 dB) not otherwise binned
H
886
6,197
MF11
Hull-mounted surface ship sonars with an active duty cycle greater than 80 percent
H
48
336
MF12
Towed array surface ship sonars with an active duty cycle greater than 80 percent
H
100
700
High-Frequency (HF): Tactical and non-tactical sources that produce signals between 10 and 100 kHz
HF1
Hull-mounted submarine sonars (
e.g.,
AN/BQQ-10)
H
10
68
HF3
Other hull-mounted submarine sonars (classified)
H
1-19
30
HF4
Mine detection, classification, and neutralization sonar (
e.g.,
AN/SQS-20)
H
1,860-1,868
11,235
HF5
Active sources (greater than 200 dB) not otherwise binned
H
352-400
2,608
HF6
Active sources (equal to 180 dB and up to 200 dB) not otherwise binned
H
1,705-1,865
12,377
HF8
Hull-mounted surface ship sonars (
e.g.,
AN/SQS-61)
H
24
168
HF9
Weapon emulating sonar source
H
257
1,772
Very High-Frequency (VHF): Tactical and non-tactical sources that produce signals greater than 100 kHz but less than 200 kHz
VHF1
Very high frequency sources greater than 200 dB
H
320
2,240
VHF2
Active sources with a frequency greater than 100 kHz, up to 200 kHz with a source level less than 200 dB
H
135
945
Anti-Submarine Warfare (ASW): Tactical sources (
e.g.,
active sonobuoys and acoustic countermeasures systems) used during ASW training and testing activities
ASW1
MF systems operating above 200 dB
H
80
560
ASW2
MF systems operating above 200 dB
C
240
1,680
ASW3
MF towed active acoustic countermeasure systems (
e.g.,
AN/SLQ-25)
H
487-1,015
4,091
ASW4
MF expendable active acoustic device countermeasures (
e.g.,
MK 3)
C
1,349-1,389
9,442
ASW5
MF sonobuoys with high duty cycles
H
80
560
Torpedoes (TORP): Source classes associated with the active acoustic signals produced by torpedoes
TORP1
Lightweight torpedo (
e.g.,
MK 46, MK 54, or Anti-Torpedo Torpedo)
C
298-360
2,258
TORP2
Heavyweight torpedo (
e.g.,
MK 48)
C
332-372
2,324
TORP3
Heavyweight torpedo test (
e.g.,
MK 48)
C
6
42
Forward Looking Sonar (FLS): Forward or upward looking object avoidance sonars used for ship navigation and safety
FLS2
HF sources with short pulse lengths, narrow beam widths, and focused beam patterns
H
24
168
Acoustic Modems (M): Systems used to transmit data through the water
M3
MF acoustic modems (greater than 190 dB)
H
1,088
7,616
Synthetic Aperture Sonars (SAS): Sonars in which active acoustic signals are post-processed to form high-resolution images of the seafloor
SAS2
HF SAS systems
H
1,312
9,184
Broadband Sound Sources (BB): Sonar systems with large frequency spectra, used for various purposes
BB1
MF to HF mine countermeasure sonar
H
48
336
BB2
HF to VHF mine countermeasure sonar
H
48
336
1
H = hours; C = count.
Table 7 describes the number of in-water explosives that could be used in any year under the planned training activities. Under the planned activities, bin use will vary annually, and the seven-year totals for the planned training activities take into account that annual variability.
Table 7—Explosive Source Class Bins Analyzed and Number of Detonations Used for Seven-Year Period for Training Activities in the NWTT Study Area
Bin
Net explosive weight
1
(lb)
2
Example explosive source
Annual
3
7-year total
E1
0.1-0.25
Medium-caliber projectiles
60-120
672
E2
>0.25-0.5
Medium-caliber projectiles
65-130
728
E3
>0.5-2.5
Explosive Ordnance Disposal Mine Neutralization
6
42
E5
>5-10
Large-caliber projectile
56-112
628
E10
>250-500
1,000 lb bomb
0-4
9
1
Net explosive weight refers to the equivalent amount of TNT. The actual weight of a munition may be larger due to other components.
2
lb = pound(s).
3
Annual Nominal—Max. Two values indicate a range from Nominal to Max annual totals.
Table 8 describes the number of in-water explosives that could be used in any year under the planned testing activities. Under the planned activities, bin use will vary annually, and the seven-year totals for the planned testing activities take into account that annual variability.
Table 8—Explosive Source Class Bins Analyzed and Number of Detonations Used for Seven-Year Period for Testing Activities in the NWTT Study Area
Bin
Net explosive weight
1
(lb)
2
Example explosive source
Annual
3
7-year total
E1
0.1-0.25
SUS buoy
8
56
E3
>0.5-2.5
Explosive sonobuoy
72
504
E4
>2.5-5
Mine Countermeasure and Neutralization
36
108
E7
>20-60
Mine Countermeasure and Neutralization
5
15
E8
>60-100
Lightweight torpedo
4
28
E11
>500-650
Heavyweight torpedo
4
28
1
Net explosive weight refers to the equivalent amount of TNT. The actual weight of a munition may be larger due to other components.
2
lb = pound(s).
3
Annual Nominal—Max.
Vessel Movement
Vessels used as part of the planned activities include ships, submarines, unmanned vessels, and boats ranging in size from small, 22 ft rigid hull inflatable boats to aircraft carriers with lengths up to 1,092 ft. Large ships greater than 60 ft generally operate at speeds in the range of 10-15 kn for fuel conservation. Submarines generally operate at speeds in the range of 8-13 kn in transits and less than those speeds for certain tactical maneuvers. Small craft (for purposes of this discussion—less than 60 ft in length) have much more variable speeds (dependent on the mission). While these speeds are representative of most events, some vessels need to temporarily operate outside of these parameters. For example, to produce the required relative wind speed over the flight deck, an aircraft carrier engaged in flight operations must adjust its speed through the water accordingly. Conversely, there are other instances, such as launch and recovery of a small rigid hull inflatable boat; vessel boarding, search, and seizure training events; or retrieval of a target when vessels will be dead in the water or moving slowly ahead to maintain steerage.
The number of military vessels used in the NWTT Study Area varies based on military training and testing requirements, deployment schedules, annual budgets, and other unpredictable factors. Many training and testing activities involve the use of vessels. These activities could be widely dispersed throughout the NWTT Study Area, but will be typically conducted near naval ports, piers, and range areas. Training and testing activities involving vessel movements occur intermittently and are variable in duration, ranging from a few hours to up to two weeks. There is no seasonal differentiation in military vessel use. Large vessel movement primarily occurs with the majority of the traffic flowing between the installations and the Operating Areas (OPAREAS). Smaller support craft would be more concentrated in the coastal waters in the areas of naval installations, ports, and ranges. The number of activities that include the use of vessels for training events is lower (approximately 10 percent) than the number for testing activities. Testing can occur jointly with a training event, in which case that testing activity could be conducted from a training vessel.
Additionally, a variety of smaller craft will be operated within the NWTT Study Area. Small craft types, sizes, and speeds vary. During training and testing, speeds generally range from 10-14 kn; however, vessels can and will, on occasion, operate within the entire spectrum of their specific operational capabilities. In all cases, the vessels/craft will be operated in a safe manner consistent with the local conditions.
Standard Operating Procedures
For training and testing to be effective, personnel must be able to safely use their sensors and weapon systems as they are intended to be used in military missions and combat operations and to their optimum capabilities. While standard operating procedures are designed for the safety of personnel and equipment and to ensure the success of training and testing activities, their implementation often yields benefits on environmental, socioeconomic, public health and safety, and cultural resources.
Because standard operating procedures are essential to safety and mission success, the Navy considers them to be part of the planned specified activities, and they have been included in the environmental analysis in the 2020 NWTT FSEIS/OEIS. Additional details on standard operating procedures were provided in our
Federal Register
notice of proposed rulemaking (85 FR 33914; June 2, 2020); please see that notice of proposed rulemaking or the Navy's application for more information.
Comments and Responses
We published the proposed rule in the
Federal Register
on June 2, 2020 (85 FR 33914), with a 45-day comment period. With that proposed rule, we requested public input on our analyses, our preliminary findings, and the
proposed regulations, and requested that interested persons submit relevant information and comments. During the 45-day comment period, we received 9,047 comments. Of this total, one submission was from the Marine Mammal Commission, two submissions were from tribes or coalitions of tribes, three submissions were from state agencies or officials, and the remaining comments were from organizations or individuals acting in an official capacity (
e.g.,
non-governmental organizations (NGOs)) and private citizens. We received some submissions that expressed general opposition toward the Navy's proposed training and testing activities and requested that NMFS not issue the regulations and LOAs, but provided no specific comments or information. These general comments have been noted, but because they did not include information pertinent to NMFS' decision, they are not addressed further.
NMFS has reviewed and considered all public comments received on the proposed rule and issuance of the LOAs. General comments that did not provide information pertinent to NMFS' decisions have been noted, but are not addressed further. All substantive comments and our responses are described below. We provide no response to specific comments that addressed species or statutes not relevant to the rulemaking under section 101(a)(5)(A) of the MMPA (
e.g.,
comments related to sea turtles). We organize our comment responses by major categories.
Impact Analysis and Thresholds
Comment 1:
A commenter stated that the criteria that the Navy has produced to estimate temporary and permanent threshold shift in marine mammals, and that NMFS applied in the proposed rule, are erroneous and non-conservative. According to the commenter, Wright (2015) has identified several statistical and numerical faults in the Navy's approach, such as pseudo-replication, use of means rather than onset (as with the treatment of blast trauma), and inconsistent treatment of data, that tend to bias the criteria towards an underestimation of effects. The commenter stated that similar and additional issues were raised by a dozen scientists during the public comment period on the draft criteria held by NMFS. The commenter asserts that the issue is NMFS' broad extrapolation from a small number of individual animals, mostly bottlenose dolphins, without taking account of what Racca
et al.
(2015b) have succinctly characterized as a “non-linear accumulation of uncertainty.” The commenter asserts that the auditory impact criteria should be revised. Another commenter noted that NMFS has not considered that repeated exposure to noise that can cause TTS can lead to PTS, or that TTS increases the likelihood of vessel strike.
Response:
The “Navy criteria” that the commenter references for estimating were developed in coordination with NMFS and ultimately finalized, following three peer reviews and three public comment periods, as NMFS' Technical Guidance for Assessing the Effects of Anthropogenic Sound on Marine Mammal Hearing-Underwater Acoustic Thresholds for Onset of Permanent and Temporary Threshold Shifts (Acoustic Technical Guidance). NMFS disagrees with the commenter's criticism about inconsistent treatment of data and any suggestion that the use of the Acoustic Technical Guidance provides erroneous results. The Acoustic Technical Guidance represents the best available science and provides thresholds and weighting functions that allow us to predict when marine mammals are likely to incur permanent threshold shift (PTS). All public comments on the Acoustic Technical Guidance, including those referenced by the commenter here, were addressed in full in the
Federal Register
notice announcing the finalization of the Acoustic Technical Guidance. We refer the reader to
https://www.federalregister.gov/documents/2016/08/04/2016-18462/technical-guidance-for-assessing-the-effects-of-anthropogenic-sound-on-marine-mammal
for full responses to those previously raised comments.
As described in the Estimated Take of Marine Mammals section, when the acoustic thresholds, the Navy model, and other inputs into the take calculation are considered, the authorized incidental takes represent the maximum number of instances in which marine mammals are reasonably expected to be taken, which is appropriate under the statute and there is no need or requirement for NMFS to authorize a larger number.
Multiple studies from humans, terrestrial mammals, and marine mammals have demonstrated less temporary threshold shift (TTS) from intermittent exposures compared to continuous exposures with the same total energy because hearing is known to experience some recovery in between noise exposures, which means that the effects of intermittent noise sources such as tactical sonars are likely overestimated. Marine mammal TTS data have also shown that, for two exposures with equal energy, the longer duration exposure tends to produce a larger amount of TTS. Most marine mammal TTS data have been obtained using exposure durations of tens of seconds up to an hour, much longer than the durations of many tactical sources (much less the continuous time that a marine mammal in the field would be exposed consecutively to those levels), further suggesting that the use of these TTS data are likely to overestimate the effects of sonars with shorter duration signals.
Regarding the suggestion of pseudoreplication and erroneous models, since marine mammal hearing and noise-induced hearing loss data are limited, both in the number of species and in the number of individuals available, attempts to minimize pseudoreplication would further reduce these already limited data sets. Specifically, with marine mammal behaviorally derived temporary threshold shift studies, behaviorally derived data are only available for two mid-frequency cetacean species (bottlenose dolphin, beluga) and two phocid (in-water) pinniped species (harbor seal and northern elephant seal), with otariid (in-water) pinnipeds and high-frequency cetaceans only having behaviorally-derived data from one species each. Arguments from Wright (2015) regarding pseudoreplication within the TTS data are therefore largely irrelevant in a practical sense because there are so few data. Multiple data points were not included for the same individual at a single frequency. If multiple data existed at one frequency, the lowest TTS onset was always used. There is only a single frequency where TTS onset data exist for two individuals of the same species: 3 kHz for bottlenose dolphins. Their TTS (unweighted) onset values were 193 and 194 dB re 1 μPa2s. Thus, NMFS believes that the current approach makes the best use of the given data. Appropriate means of reducing pseudoreplication may be considered in the future, if more data become available. Many other comments from Wright (2015) and the comments from Racca
et al.
(2015b) appear to be erroneously based on the idea that the shapes of the auditory weighting functions and TTS/PTS exposure thresholds are directly related to the audiograms;
i.e.,
that changes to the composite audiograms would directly influence the TTS/PTS exposure functions (
e.g.,
Wright (2015) describes weighting functions as “effectively the mirror image of an audiogram” (p. 2) and states, “The underlying goal was to estimate how much a sound level needs to be above
hearing threshold to induce TTS.” (p. 3)). Both statements are incorrect and suggest a fundamental misunderstanding of the criteria/threshold derivation. This would require a constant (frequency-independent) relationship between hearing threshold and TTS onset that is not reflected in the actual marine mammal TTS data. Attempts to create a “cautionary” outcome by artificially lowering the composite audiogram thresholds would not necessarily result in lower TTS/PTS exposure levels, since the exposure functions are to a large extent based on applying mathematical functions to fit the existing TTS data.
Please refer to the response to Comment 9 for additional information regarding the use of “means rather than onset” in the analysis of blast trauma.
Regarding the comment about repeated exposures to TTS leading to PTS, NMFS is aware of studies by Kujawa and Liberman (2009) and Lin
et al.
(2011), which found that despite completely reversible TS that leave cochlear sensory cells intact, large (but temporary) TS could cause synaptic level changes and delayed cochlear nerve degeneration in mice and guinea pigs. However, the large TS (
i.e.,
maximum 40 decibel dB) that led to the synaptic changes shown in these studies are in the range of the large shifts used by Southall
et al.
(2007) and in NMFS Acoustic Technical Guidance (2018) to define PTS onset (
i.e.,
40 dB). There is no evidence indicating that smaller levels of TTS would lead to similar changes or the long-term implications of irreversible neural degeneration and NMFS has included several conservative assumptions in its protocol for examining marine mammal hearing loss data
(e.g.,
using a 6 dB threshold shift to represent TTS onset, not directly accounting for exposures that did not result in threshold shifts, assuming there is no recovery with the 24-h baseline accumulation period or between intermittent exposures). Moreover, as described in the final rule, TTS incurred as a result of exposures to Navy NWTT activities is expected to be of a smaller degree and, further, no individual is expected to incur repeated exposures of TTS in a manner that could accrue to PTS. Nonetheless, NMFS acknowledges the complexity of sound exposure on the nervous system, and will re-examine this issue as more data become available. Separately, the commenter provides no credible evidence to support the speculative assertion that TTS increases the likelihood of vessel strike of marine mammals.
Comment 2:
A commenter recommended that NMFS clarify whether and how the Navy incorporated uncertainty in its density estimates for its animat modeling specific to NWTT and if uncertainty was not incorporated, re-estimate the numbers of marine mammal takes based on the uncertainty inherent in the density estimates provided in Department of the Navy (2019) or the underlying references (Jefferson
et al.,
2017, Smultea
et al.,
2017, NMFS SARs,
etc.
).
Response:
Uncertainty was incorporated into the density estimates used for modeling and estimating take for NMFS' rule. Where available, a coefficient of variation (CV) was used to represent uncertainty in the species-specific density estimates. The CV was incorporated into the acoustic effects model by randomly varying the number of animats distributed for each scenario within the range described by the CV. If a measure of uncertainty was not available, then the number of animats distributed in the model remained the same for each modeled scenario. Multiple iterations of each modeled scenario were run until the results converged with minimal variation, meaning that even without incorporating a CV into the animat distribution, uncertainty in the exposure results were minimized.
The commenter is referred to the technical report titled
Quantifying Acoustic Impacts on Marine Mammals and Sea Turtles: Methods and Analytical Approach for Phase III Training and Testing
(U.S. Department of the Navy, 2018) for clarification on the consideration of uncertainty in density estimates. Specifically, see Section 4.2 (Marine Species Distribution Builder) of the technical report where details are provided on how statistical uncertainty surrounding density estimates was incorporated into the modeling for the NWTT Study Area, as has been done for all other recent NMFS and Navy analyses of training and testing at sea. To the commenter's more specific question, as with the 2018/2020 Hawaii-Southern California Training and Testing (HSTT) final rules and 2020 Mariana Islands Training and Testing (MITT) final rule, a lognormal distribution was used in the density regression model. Uncertainty was incorporated into the take estimation through the density estimates and it is not necessary to re-estimate the take numbers for marine mammals.
Comment 3:
A commenter recommended that NMFS specify in the preamble to the final rule whether the data regarding behavioral audiograms (Branstetter
et al.,
2017, Kastelein
et al.,
2017b) and TTS (Kastelein
et al.,
2017a and c, Popov
et al.,
2017, Kastelein
et al.,
2018a and 2019b, c, and d) support the continued use of the current weighting functions and PTS and TTS thresholds.
Response:
NMFS has carefully considered the references that the commenter cites and the new data included in those articles are consistent with the thresholds and weighting functions included in the current version of the Acoustic Technical Guidance (NMFS, 2018). Furthermore, the recent peer-reviewed updated marine mammal noise exposure criteria by Southall
et al.
(2019a) provide identical PTS and TTS thresholds and weighting functions to those provided in NMFS' Acoustic Technical Guidance. NMFS will continue to review and evaluate new relevant data as it becomes available and consider the impacts of those studies on the Acoustic Technical Guidance to determine what revisions/updates may be appropriate.
Comment 4:
A commenter stated that the Navy, and in turn NMFS, has not provided adequate justification for ignoring the possibility that single underwater detonations can cause a behavioral response. The commenter recommends that NMFS estimate and ultimately authorize behavior takes of marine mammals during all explosive activities, including those that involve single detonations. In a similar comment, another commenter stated that the literature on responses to explosions does not distinguish between single and multiple detonations, and asserts that it is arbitrary for NMFS, in estimating takes and assessing impacts, to assume that only multiple rounds of in-water detonations can cause Level B harassment takes by behavioral disturbance.
Response:
NMFS does not ignore the possibility that single underwater detonations can cause a behavioral response. The current take estimate framework allows for the consideration of animals exhibiting behavioral disturbance during single explosions as they are counted as “taken by Level B harassment” if they are exposed above the TTS threshold, which is only 5 dB higher than the behavioral harassment threshold. We acknowledge in our analysis that individuals exposed above the TTS threshold may also be harassed by behavioral disruption and those potential impacts are considered in the negligible impact determination. Neither NMFS nor the Navy are aware of evidence to support the assertion that animals will have significant behavioral responses (
i.e.,
those that would rise to the level of a take) to temporally and
spatially isolated explosions at received levels below the TTS threshold. However, if any such responses were to occur, they would be expected to be few and to result from exposure to the somewhat higher received levels bounded by the TTS thresholds and would, thereby, be accounted for in the take estimates. The derivation of the explosive injury criteria is provided in the 2017 technical report titled
Criteria and Thresholds for U.S. Navy Acoustic and Explosive Effects Analysis (Phase III).
Comment 5:
A commenter stated that the behavioral response functions (BRFs) rely on captive animal studies and the risk functions do not incorporate a number of relevant studies on wild marine mammals (specifically referencing a passive acoustic study on blue whales). The commenter states that some were included in the only published quantitative synthesis of behavioral response data, Gomez
et al.
(2016), while others appeared after that synthesis was published, and after the Navy produced its BRFs two years ago. The commenter asserts that exclusion of those studies fails to meet regulatory requirements (citing to National Environmental Policy Act (NEPA) regulations) that base evaluation of impacts on research methods generally accepted in the scientific community and that the result is arbitrary.
The commenter asserts that it is not clear from the proposed rule, the 2020 NWTT DSEIS/OEIS, or the Navy's associated technical report on acoustic “criteria and thresholds” exactly how each of the studies considered relevant were applied in the analysis, or how the functions were fitted to the data, but the available evidence on behavioral response raises concerns that—notwithstanding the agencies' claims to the contrary—the functions are not conservative for some species. For this reason and others, the commenter requests that NMFS make additional technical information available, including expert elicitation and peer review (if any), so that the public can fully comment pursuant to the Administrative Procedure Act (APA).
Response:
We refer the commenter to the Criteria and Thresholds for the U.S. Navy Acoustic and Explosive Effects Analysis (Phase III) Technical Report (U.S. Department of the Navy, 2017) for details on how the Navy accounted for the differences in captive and wild animals in the development of the behavioral response risk functions, which NMFS has evaluated and deemed appropriate to incorporate into the analysis in the rule. The appendices to this report detail the specific data points used to generate the BRFs. Data points come from published data that is readily available and cited within the technical report.
The Navy used the best available science in the analysis, which has been reviewed by external scientists and approved by NMFS. The Navy considered all data available at the time for the development of updated criteria and thresholds, and limiting the data to the small number of field studies would not provide enough data with which to develop the new risk functions. In addition, the Navy accounted for the fact that captive animals may be less sensitive, and the scale at which a moderate-to-severe response was considered to have occurred is different for captive animals than for wild animals, as the Navy understands those responses will be different. The new risk functions were developed in 2016, before several recent papers were published or the data were available. The Navy and NMFS continue to evaluate the information as new science is made available. The criteria have been rigorously vetted within the Navy community, among scientists during expert elicitation, and then reviewed by the public before being applied. It is unreasonable to revise and update the criteria and risk functions every time a new paper is published. NMFS concurs with the Navy's evaluation and conclusion that there is no new information that necessitates changing the acoustic thresholds at this time.
These new papers provide additional information, and the Navy is considering them for updates to the criteria in the future, when the next round of updated criteria will be developed. Regarding consideration of research findings involving a passive acoustic study on blue whale vocalizations and behavior, the Navy considered multiple recent references, including but not limited to: Paniagua-Mendoza, 2017; Lesage, 2017; DeRuiter, 2017; Mate, 2016; Lomac-MacNair, 2016; Friedlaender, 2016; and Mate, 2015. Thus far, no new information has been published or otherwise conveyed that would fundamentally change the assessment of impacts or conclusions of this rule. To be included in the BRF, data sets needed to relate known or estimable received levels to observations of individual or group behavior. Melcon
et al.
(2012) does not relate observations of individual/group behavior to known or estimable received levels at that individual/group. In Melcon
et al.
(2012), received levels at the HARP buoy averaged over many hours are related to probabilities of D-calls, but the received level at the blue whale individuals/group are unknown.
Comment 6:
Commenters recommended that NMFS refrain from using cut-off distances in conjunction with the Bayesian BRFs and re-estimate the numbers of marine mammal takes based solely on the Bayesian BRFs, as the use of cut-off distances could be perceived as an attempt to reduce the numbers of takes. One commenter suggested that the actual cut-off distances used by the Navy appear to be unsubstantiated and questioned several of the choices made in the development of the cutoff distances (although alternate recommendations were not included).
Response:
The consideration of proximity (cut-off distances) was part of the criteria developed in consultation between the Navy and NMFS, and is appropriate based on the best available science which shows that marine mammal responses to sound vary based on both sound level and distance. Therefore these cut-off distances were applied within the Navy's acoustic effects model. The derivation of the BRFs and associated cut-off distances is provided in the 2017 technical report titled
Criteria and Thresholds for U.S. Navy Acoustic and Explosive Effects Analysis (Phase III).
To account for non-applicable contextual factors, all available data on marine mammal reactions to actual Navy activities and other sound sources (or other large scale activities such as seismic surveys when information on proximity to sonar sources was not available for a given species group) were reviewed to find the farthest distance to which significant behavioral reactions were observed. For use as distance cut-offs to be used in conjunction with the BRFs, these distances were rounded up to the nearest 5 or 10 km interval, and for moderate to large scale activities using multiple or louder sonar sources, these distances were greatly increased—doubled in most cases. The Navy's BRFs applied within these distances provide technically sound methods reflective of the best available science to estimate the impact and potential take for the actions analyzed within the 2020 NWTT FSEIS/OEIS and included in this rule. NMFS has independently assessed the thresholds used by the Navy to identify Level B harassment by behavioral disturbance (referred to as “behavioral harassment thresholds” throughout the rest of the rule) and finds that they appropriately apply the best available science and it is not necessary to recalculate take estimates.
The commenters also specifically expressed concern that distance “cut-
offs” alleviate some of the exposures that would otherwise have been counted if the received level alone were considered. It is unclear why the commenters find this inherently inappropriate, as this is what the data show. There are multiple studies illustrating that in situations where one would expect behavioral disturbance of a certain degree because of the received levels at which previous responses were observed, it has not occurred when the distance from the source was larger than the distance of the first observed response.
Comment 7:
A commenter stated that dipping sonar, like hull-mounted sonar, appears to be a significant predictor of deep-dive rates in beaked whales, with the dive rate falling significantly (
e.g.,
to 35 percent of that individual's control rate) during sonar exposure, and likewise appears associated with habitat abandonment. According to the commenter, the data sources used to produce the Navy's BRFs concern hull-mounted sonar, an R/V-deployed sonar playback, or an in-pool source. According to the commenter, the generic BRF for beaked whales used in the rule does not incorporate their heightened response to these sources, although such a response would be presumed to shift its risk function “leftward.” Nor do the response functions for other species account for this difference, although unpredictability is known to exacerbate stress response in a diversity of mammalian species and should conservatively be assumed, in this case, to lead to a heightened response in marine mammal species other than beaked whales.
Response:
The best available science was used to develop the BRFs. The current beaked whale BRF acknowledges and incorporates the increased sensitivity observed in beaked whales during both behavioral response studies and during actual Navy training events, as well as the fact that dipping sonar can have greater effects than some other sources with the same source level. Specifically, the distance cut-off for beaked whales is 50 km, larger than any other group. Moreover, although dipping sonar has a significantly lower source level than hull-mounted sonar, it is included in the category of sources with larger distance cut-offs, specifically in acknowledgement of its unpredictability and association with observed effects. This means that “takes” are reflected at lower received levels that would have been excluded because of the distance for other source types. An article referenced by the commenter (Associating patterns in movement and diving behavior with sonar use during military training exercises: A case study using satellite tag data from Cuvier's beaked whales at the Southern California Anti-submarine Warfare Range (Falcone
et al.,
2017)) was not available at the time the BRFs were developed. However, NMFS and the Navy have reviewed the article and concur that neither this article nor any other new information that has been published or otherwise conveyed since the BRFs were developed changes the assessment of impacts or conclusions in the 2020 NWTT FSEIS/OEIS or in this rulemaking. Additionally, the current beaked whale BRF covers the responses observed in this study since the beaked whale risk function is more sensitive than the other risk functions at lower received levels. The researchers involved with the study continue to further refine their analytical approach and integrate additional statistical parameters for future reporting. Nonetheless, the new information and data presented in the article were thoroughly reviewed by NMFS and the Navy and will be quantitatively incorporated into future BRFs, as appropriate, when and if other new data that would meaningfully change the functions would necessitate their revision. Furthermore, ongoing beaked whale monitoring at the same site where the dipping sonar tests were conducted has not documented habitat abandonment by beaked whales. Passive acoustic detections of beaked whales have not significantly changed over ten years of monitoring (DiMarzio
et al.,
2018, updated in 2020). From visual surveys in the same area since 2006, there have been repeated sightings of the same individual beaked whales, beaked whale mother-calf pairs, and beaked whale mother-calf pairs with mothers on their second calf (Schorr
et al.,
2018, 2020). Satellite tracking studies of beaked whales documented high site fidelity to this area (Schorr
et al.,
2018, updated in 2020).
Comment 8:
A commenter recommends that NMFS: (1) Explain why, if the constants and exponents for onset mortality and onset slight lung injury thresholds for the current phase of incidental take rulemaking for the Navy (Phase III) have been amended to account for lung compression with depth, they result in lower rather than higher absolute thresholds when animals occur at depths greater than 8 m and (2) specify what additional assumptions were made to explain this counterintuitive result.
Response:
The derivation of the explosive injury equations, including any assumptions, is provided in the 2017 technical report titled
Criteria and Thresholds for U.S. Navy Acoustic and Explosive Effects Analysis (Phase III).
Specifically, the equations were modified for the current rulemaking period (Phase III) to fully incorporate the injury model in Goertner (1982), specifically to include lung compression with depth. NMFS independently reviewed and concurred with this approach.
The impulse mortality/injury equations are depth dependent, with thresholds increasing with depth due to increasing hydrostatic pressure in the model for both the previous 2015-2020 phase of rulemaking (Phase II) and Phase III. The underlying experimental data used in Phase II and Phase III remain the same, and two aspects of the Phase III revisions explain the relationships the commenter
Notes:
(1) The numeric coefficients in the equations are computed by inserting the Richmond
et al.
(1973) experimental data into the model equations. Because the Phase III model equation accounts for lung compression, the plugging of experimental exposure values into a different model results in different coefficients. The numeric coefficients are slightly larger in Phase III versus Phase II, resulting in a slightly greater threshold near the surface.
(2) The rate of increase for the Phase II thresholds with depth is greater than the rate of increase for Phase III thresholds with depth because the Phase III equations take into account the corresponding reduction in lung size with depth (making an animal more vulnerable to injury per the Goertner model), as the commenter notes.
Comment 9:
A commenter recommended that NMFS use onset mortality, onset slight lung injury, and onset gastrointestinal (GI) tract injury thresholds rather than the 50-percent thresholds to estimate both the numbers of marine mammal takes and the respective ranges to effect. If NMFS does not implement the recommendation, the commenter further recommends that NMFS (1) specify why it is inconsistently basing its explosive thresholds for Level A harassment on onset of PTS and Level B harassment on onset of TTS and onset behavioral response, while the explosive thresholds for mortality and Level A harassment are based on the 50-percent criteria for mortality, slight lung injury, and GI tract injury, (2) provide scientific justification supporting the assumption that slight lung and GI tract injuries are less severe than PTS and thus the 50-percent rather than onset criteria are more appropriate for estimating Level A harassment for those types of injuries,
and (3) justify why the number of estimated mortalities should be predicated on at least 50 percent rather than 1 percent of the animals dying.
Another commenter also stated that they do not understand why the Navy and NMFS use the 50 percent average for the explosive impact analysis while using onset for purposes of assessing the effectiveness of the Navy's mitigation zones. This commenter also stated that this approach is not consistent with the probability standards set forth in the MMPA. The MMPA incorporates a standard of “significant potential” into its definition of “injury” for military readiness activities; this standard plainly differs from the higher “likelihood” standard that applies to behavioral disruption. And while the probability standard for mortality is not specifically defined in the Act, Congress expressly amended the MMPA in 1994 to incorporate a “potential” standard in the wake of the Ninth Circuit decision in
U.S.
v.
Hiyashi,
22 F.3d 859 (9th Cir. 1993). If NMFS is to satisfy the plain language of the MMPA, and provide a more conservative estimate of harm, it cannot base its mortality and injury estimates on the mean.
Response:
First, we note an error in one of the commenters' assertions. The BRFs used in the behavioral harassment thresholds are not based on the onset of any behavioral response. They are based on responses at or above a severity at which we believe “take” occurs, therefore the BRFs do not predict onset behavioral response. Also, the “onset” of TTS is not when there is any measurable TTS (
i.e.,
0.5, 1 dB); we've defined the onset of TTS as where there is a consistently measurable amount of TTS, which has been defined as 6 dB of TTS. Additionally, the weighting function components of the TTS thresholds are based on the average of all of the data points. Since the PTS threshold is derived from an offset of the TTS threshold, this same averaging concept holds true for PTS criteria.
For explosives, the type of data available are different than those available for hearing impairment, and this difference supports the use of different prediction methods. Nonetheless, as appropriate and similar to take estimation methods for PTS, NMFS and the Navy have used a combination of exposure thresholds and consideration of mitigation to inform the take estimates. The Navy used the range to 1 percent risk of onset mortality and onset injury (also referred to as “onset” in the 2020 NWTT FSEIS/OEIS) to inform the development of mitigation zones for explosives. Ranges to effect based on 1 percent risk criteria to onset injury and onset mortality were examined to ensure that explosive mitigation zones would encompass the range to any potential mortality or non-auditory injury, affording actual protection against these effects. In all cases, the mitigation zones for explosives extend beyond the range to 1 percent risk of onset non-auditory injury, even for a small animal (representative mass = 5 kg). Given the implementation and expected effectiveness of this mitigation, the application of the indicated threshold is appropriate for the purposes of estimating take. Using the 1 percent onset non-auditory injury risk criteria to estimate take would result in an over-estimate of take, and would not afford extra protection to any animal. Specifically, calculating take based on marine mammal density within the area that an animal might be exposed above the 1 percent risk to onset injury and onset mortality criteria would over-predict effects because many of those exposures will not happen because of the effective mitigation. The Navy, in coordination with NMFS, has determined that the 50 percent incidence of onset injury and onset mortality occurrence is a reasonable representation of a potential effect and appropriate for take estimation, given the mitigation requirements at the 1 percent onset injury and onset mortality threshold, and the area ensonified above this threshold would capture the appropriate reduced number of likely injuries.
While the approaches for evaluating non-auditory injury and mortality are based on different types of data and analyses than the evaluation of PTS and behavioral disturbance, and are not identical, NMFS disagrees with the commenter's assertion that the approaches are inconsistent, as both approaches consider a combination of thresholds and mitigation (where applicable) to inform take estimates. For the same reasons, it is not necessary for NMFS to “provide scientific justification supporting the assumption that slight lung and GI tract injuries are less severe than PTS,” as that assumption is not part of NMFS' rationale for the methods used. NMFS has explained in detail its justification for the number of estimated mortalities, which is based on both the 50 percent threshold and the mitigation applied at the one percent threshold. Further, we note that many years of Navy monitoring following explosive exercises has not detected evidence that any injury or mortality has resulted from Navy explosive exercises with the exception of one incident with dolphins in California, after which mitigation was adjusted to better account for explosives with delayed detonations (
i.e.,
zones for events with time-delayed firing were enlarged).
Further, for these reasons, the methods used for estimating mortality and non-auditory injury are appropriate for estimating take, including determining the “significant potential” for non-auditory injury consistent with the statutory definition of Level A harassment for military readiness activities, within the limits of the best available science. Using the one percent threshold would be inappropriate and result in an overestimation of effects, whereas given the mitigation applied within this larger area, the 50 percent threshold results an appropriate mechanism for estimating the significant potential for non-auditory injury.
Comment 10:
A commenter had concerns regarding the various areas, abundance estimates, and correction factors that the Navy used for pinnipeds. The commenter referenced information in the context of both what the Navy used and what the commenter argued they should have used and summarized the discussion with several recommendations.
Broadly, the commenter stated that since NMFS used the draft 2019 Stock Assessment Reports (SARs) or the most recently finalized SAR for the abundance estimates in its negligible impact determination analyses (Tables 9 and 52-57 in the
Federal Register
notice), it also must use the most recent abundance estimates to inform the associated densities and resulting take estimates as those abundance estimates represent the best available science.
The commenter noted that the abundance estimate for northern fur seals was based on pup count data from 2014 and did not include the more recent data from Bogoslof Island in 2015 and from St. Paul and St. George in 2016. For northern fur seals, the commenter recommended that NMFS revise the density based on the abundance estimate that includes data from Bogoslof Island in 2015 and from St. Paul and St. George in 2016.
The commenter noted that the abundance estimate for Guadalupe fur seals was based on pup count data from 2008 and 2010 and did not include the more recent survey data from 2013-2015 and associated correction factors. For Guadalupe fur seals, the commenter recommended that NMFS revise the density based on abundance data from 2013-2015 at both Isla Guadalupe and Isla San Benito.
The commenter stated that the abundance estimate for Steller sea lions was based on pup and non-pup count and trend data from 2015 and did not incorporate the more recent trend data from 2017. The commenter also noted that the Navy applied non-pup growth rates to the non-pup and pup abundance estimates rather than applying the non-pup growth rates to the non-pup abundances and the pup growth rates to the pup abundances. For Steller sea lions, the commenter recommended that NMFS revise the density based on adjusting the 2015 pup and non-pup data using the trend data from 2017, applying the non-pup growth rate to the non-pup counts and the pup growth rates to the pup counts.
For Guadalupe fur seal, Steller sea lion, California sea lions, harbor seals, and elephant seals, the commenter recommended that NMFS revise the densities based on applying the relevant growth rates up to at least 2020.
For harbor seals in the Strait of Juan de Fuca and the San Juan Islands, the commenter recommended that NMFS revise the densities based on assuming that 46 percent of the animals would be in the water at a given time from Huber
et al.
(2001).
Based on the recommendations above, the commenter recommended that NMFS re-estimate the numbers of takes accordingly in the final rule.
Response:
The Navy provided NMFS clarification regarding the referenced concerns about areas, abundance estimates, and correction factors that were used for pinnipeds. We first note that take estimation is not an exact science. There are many inputs that go into an estimate of marine mammal exposure, and the data upon which those inputs are based come with varying levels of uncertainty and precision. Also, differences in life histories, behaviors, and distributions of stocks can support different decisions regarding methods in different situations. Further, there may be more than one acceptable method to estimate take in a particular situation. Accordingly, while the applicant bears the responsibility of providing by species or stock the estimated number and type of takes (see 50 CFR 216.104(a)(6)) and NMFS always ensures that an applicant's methods are technically supportable and reflect the best available science, NMFS does not prescribe any one method for estimating take (or calculating some of the specific take estimate components that the commenter is concerned about). NMFS reviewed the areas, abundances, and correction factors used by the Navy to estimate take and concurs that they are appropriate. While some of the suggestions the commenter makes could provide alternate valid ways to conduct the analyses, these modifications are not required in order to have equally valid and supportable analyses. In addition, we note that (1) some of the specific recommendations that the commenter makes are largely minor in nature within the context of our analysis (
e.g.,
“46 not 37 percent”) and (2) even where the recommendation is somewhat larger in scale, given the ranges of the majority of these stocks, the size of the stocks, and the number and nature of pinniped takes, recalculating the estimated take for any of these pinniped stocks using the commenter's recommended changes would not change NMFS' assessment of impacts on the rates of recruitment or survival of any of these stocks, or the negligible impact determinations. Below, we address the commenter's issues in more detail and, while we do not explicitly note it in every section, NMFS has reviewed the Navy's analysis and choices in relation to these comments and concurs that they are technically sound and reflect the best available science.
Northern fur seal
—The Navy analyzed unpublished tagging data provided by subject matter experts at NMFS' Alaska Fisheries Science Center (AKFSC). The Navy also did not integrate the 2015 data from Bogoslof Island suggested by the commenter based on advice from subject matter experts at the AKFSC, due to a volcanic eruption at the rookery on Bogoslof Island where a portion of the counts are made, which in the opinion of the AKFSC experts skewed the 2015 data. Therefore, the Navy found that incorporating this data would not reflect the best available science. NMFS concurs with this assessment, and therefore, has not included this information in the take estimation in this final rule. Regarding the recommendation for NMFS to revise the density based on the abundance estimate from St. Paul and St. George in 2016, to complete the modeling on schedule, the density data available at that time from the final 2016 SAR (Muto
et al.,
2017) were used. Note that the latest pup counts reported in the final 2019 SAR (Muto
et al.,
2020) using the more recent data from Bogoslof Island in 2015 and St. Paul and St. George in 2016 result in a lower pup count than the one used in the density calculation, which suggests that the estimates used for this final rule are likely conservative.
Guadalupe fur seal
—The Navy Marine Species Density Database (NMSDD) technical report describes density estimates that were used in the Navy's acoustics effects model. To complete the modeling on schedule, the density data available at that time from the final 2016 SAR (Carretta
et al.,
2017) were used. The initial abundance estimate of 20,000 fur seals was based on surveys between 2008 and 2010 as the commenter points out, but to account for a likely increasing population trend, the Navy applied a growth rate of 7.64 percent per year to estimate an abundance for the year 2017. That resulted in an abundance of 33,485 fur seals (a 67 percent increase over the reported abundance of 20,000). The final 2019 SAR (Carretta
et al.,
2020) reported comparable abundance estimates based on the later surveys, some of which were from sources published in 2018, and an estimated growth rate of 5.9 percent, less than the growth rate applied by the Navy. The Navy's abundance estimate for the year 2017 is consistent with the latest abundance estimates.
Steller sea lion
—As stated above, the NMSDD technical report describes density estimates that were used in the Navy's acoustics effects model. To complete the modeling on schedule, the density data available at that time from the final 2016 SAR (Muto
et al.,
2017) were used. Steller sea lion densities were calculated independently for regional populations in Washington, Oregon, California, and southeast Alaska, consistent with the stock assessment reports. No trend data were (or are currently) estimated for pups in Washington, therefore, the non-pup growth rate of 8.77 percent per year was used for the entire population. In addition, the baseline abundance for Washington sea lions was increased over the abundance from the stock assessment report based on data reported in Wiles (2015) before the growth rate was applied to project a 2017 abundance. For sea lions in Oregon, California, and southeast Alaska the non-pup growth rate was used, because the number of non-pups in each population was substantially greater than the number of pups. Using separate growth rates for pups and non-pups in all three regions results in less than a 1 percent increase in the projected 2017 abundance. The associated change in the density is minimal and would not change the results of NMFS' or the Navy's analysis of acoustic impacts on Steller sea lions.
Harbor seal
—Density estimates for harbor seal in the Strait of Juan de Fuca and San Juan Islands were based on sighting data provided by the Washington Department of Fish and Game (Jeffries, 2017). In the context of analyzing that data, a 37 percent in-
water correction factor was applied to the abundance estimate, which is specific to southern Puget Sound. Huber
et al.
(2001) noted that a 46 percent in-water correction factor would have been more appropriate given that the survey location was in the Strait. However, there were specific haulout factors for other areas within the Study Area that gave lower estimates throughout the Inland Waters. Subject matter experts from the Alaska Fisheries Science Center and the Northwest Fisheries Science Center concurred with the Navy's use of 37 percent as being most representative.
Regarding revising the densities based on applying the relevant growth rates up to at least 2020, the density estimates are based on sighting numbers from surveys over many years to encompass variation and are not future predictions. It would not be appropriate to base densities on growth rates. The densities do not incorporate abundances or estimates of growth rate since the abundances for population and their population trend (reduction or growth) are not directly applicable to the density within a given area. Subject matter experts at the NMFS Alaska Fisheries Science Center advised in 2015 and again in 2019 that growth/decline rates provided in the SARs should not be used to project future population numbers for use in the Navy's analysis where abundance have been integrated into the analysis. NMFS concurs with this assessment and has not applied the growth rates in the take estimation in this final rule.
Additionally, the Navy's purpose in applying an annual growth rate to estimate pinniped abundances in 2017 was to account for stock assessment report abundances that were based on surveys conducted several years prior to 2017. The intent was to update an older abundance estimate to the time of the Navy's analysis, not to predict abundances several years into the future. Projecting abundances from the past to the present (2017) allowed adjustments. For example, the growth rate for Guadalupe fur seal reported in the 2016 SAR (Carretta
et al.,
2017) was 10.3 percent; however, as the commenter pointed out, that rate is based on survey data from 2008-2010. Subsequently, the 2015-2016 unusual mortality event (UME) occurred and the growth rate needed to be revised, which the Navy did. Projections extending into the future would not have allowed these types of corrections.
Please see Comment 18 for additional information about the harbor seal abundance estimates included in this final rule.
Comment 11:
A commenter stated that a majority of the data that the Navy reviews and uses to determine species population density and breeding grounds is admittedly old and is not the most accurate representation of the species population or their geographic location. In its requirements for an authorization, the MMPA clearly states that requesters must include “the species and numbers of marine mammals likely to be found within the activity area” in order to demonstrate the requesting party's understanding of their activity impact on the animals and habitat. Normally, this sort of data requires up-to-date assessment reports, statistics, and accurate data that accurately portray the information that is necessary to require an authorization under the MMPA. However, the commenter stated that the Navy is violating the MMPA by providing outdated data from 2012 and 2014 to account for current patterns of marine activities in 2020-2027, even though they are conducting training exercises in the same Northwest waters where they are hoping to continue practicing for another seven years.
The commenter suggested that the Navy should instead provide accurate up-to-date surveys of the activity areas as well as data for a long-term projection for at least 30 years of activity in the area if it continues to expect to apply for the same authorization over and over again.
Response:
The
U.S. Navy Marine Species Density Database Phase III for the Northwest Training and Testing Study Area Final Technical Report
includes an in-depth description of the process used to derive density estimates for marine mammal species occurring in the NWTT Study Area, and to provide a summary of species-specific and area-specific density estimates incorporated into the Marine Species Density Database. NMFS concurs that as described in the report, the process the Navy uses ensures that the density estimates reflect the best available data. Given the extensive and comprehensive process, it is not possible (or necessary) to update the density estimates or information about marine mammal breeding grounds each time a new paper is published, nor does the commenter provide additional data or publications that should have been incorporated into the density estimates or identify new information related to breeding grounds. However, the Navy will continue to incorporate, and NMFS will continue to consider, additional data for the next phase of Navy training and testing activities (Phase IV). Through the use of the Navy's methodology and the data inputs used, which were coordinated with NMFS, NMFS has ensured that this final rule incorporates the best available information related to marine mammal density and breeding areas in this final rule.
The commenter suggested that the Navy should provide accurate, up-to-date surveys of the activity areas, as well as data for a long-term projection for at least 30 years of activity in the NWTT Study Area. As discussed in the Monitoring section of this final rule, the Navy funds numerous marine mammal monitoring efforts, and this data is incorporated into the density and abundance estimates as appropriate. For example, this final rule incorporates new data regarding harbor seal abundance in NWTT inland waters from Navy-funded surveys (see the Analysis and Negligible Impact Determination section of this final rule). It is unclear what the commenter means by suggesting that the Navy provide a long-term projection for at least 30 years of activity in the area; however, NMFS notes that the current authorization is limited to seven years. NMFS will conduct a new analysis on the potential effects to marine mammals assuming the Navy seeks an authorization for training and testing activities beyond 2027 in the NWTT Study Area, and will ensure that the best available science, including new data as available, is included in that analysis.
Comment 12:
A commenter recommended that NMFS require the Navy to provide the method(s) by which species-specific cetacean densities were calculated for Western Behm Canal and cite the primary literature from which those data originated in the report (Department of the Navy (2019)). The commenter states that that level of information should be provided in all technical reports that underpin the Navy's density databases for future Phase III and IV DSEISs, DEISs, and proposed rules.
Response:
There were two primary sources of density data used to establish cetacean density estimates for Behm Canal: (1) The marine mammal occurrence/density report prepared in support of Navy activities at the Southeast Alaska Acoustic Measurement Facility (U.S. Department of the Navy, 2010) and (2) Density estimates derived by the National Marine Mammal Laboratory, Alaska Fisheries Science Center based on systematic surveys conducted in Southeast Alaska (
e.g.,
Dahlheim
et al.,
2015). These sources were cited as appropriate in the species-specific sections of Department of the Navy (2020); methods by which species-
specific density estimates were calculated are also described in Department of the Navy (2020). Multiple sources were used to establish pinniped density estimates for Behm Canal. All are cited as appropriate and methods described within the species-specific sections of Department of the Navy, 2020 (U.S. Navy Marine Species Density Database Phase III for the Northwest Training and Testing Study Area: Technical report. Naval Facilities Engineering Command Pacific, Pearl Harbor, Hawaii. 258 pages).
Comment 13:
A commenter stated that the delineation of Biologically Important Areas by NMFS, the updates made by the Navy to its predictive habitat models, and evidence of additional important habitat areas within the NWTT Study Area provide the opportunity for the agencies to improve upon their current approach to the development of alternatives by improving resolution of their analysis of operations.
The commenter stated that recognizing that important habitat areas imply the non-random distribution and density of marine mammals in space and time, both the spatial location and the timing of training and testing events in relation to those areas is a significant determining factor in the assessment of acoustic impacts. Levels of acoustic impact are likely to be under- or over-estimated depending on whether the location of the modeled event is further from the important habitat area, or closer to it, than the actual event. Thus, there is a need for the Navy to compile and provide more information regarding the number, nature, and timing of testing and training events that take place within, or in close proximity to, important habitat areas, and to refine its scale of analysis of operations to match the scale of the habitat areas that are considered to be important. And there is a need for NMFS to demand it.
The commenter stated that while the 2019 NWTT DSEIS/OEIS, in assessing environmental impacts on marine mammals, breaks down estimated impacts by population, little detail is provided about assumptions concerning modeled locations and times of year. See,
e.g.,
DSEIS at 2-28 to 2-38 (
e.g.,
defining numerous activities as simply occurring “[o]ffshore”). The commenter further stated that the proposed rule notice adds nothing further, making it impossible for the public to assess the reasonableness of NMFS take estimates and negligible impact analysis in capturing the distribution of the activities proposed in the document. Additionally, the commenter asserts that the lack of definition in activity locations means that the agency cannot ensure takes are kept below authorized levels—and that sufficient measures are taken to protect particularly vulnerable marine mammal populations, such as the critically endangered Southern Resident killer whale and the struggling California gray whale.
The commenter recommended that NMFS require the Navy to produce further information on modeled locations and, if activities are not limited through the authorization process to specific geographic areas, to determine a worst-case take estimate for each species or population.
Another commenter stated that the Navy should provide NMFS with details on proposed timing of their training and testing activities and adjust the timing of their activities to minimize such overlap—such as through seasonal closures. The commenter stated that the DSEIS and the LOA application did not detail the times of year during which the proposed activities would take place. To issue a LOA, NMFS requires that proposed actions “be well-planned with enough detailed information to allow for a robust analysis of the entire duration of your planned activity,” which is lacking here. The Southern Resident killer whales have exhibited seasonality in their movements, and information from tagging studies, coastal surveys and passive acoustic monitoring allows some degree of understanding of seasonal areas for when and where they may be traveling and foraging. Any overlap in their seasonal movements and the Navy's testing and training activities will increase adverse impacts.
Response:
This final rule and the 2020 NWTT FSEIS/OEIS are structured to provide flexibility in training and testing locations, timing, and number. Many factors influence actual training and testing locations that cannot be predicted in advance (
e.g.,
weather), so the analysis must allow for flexibility. The analysis must consider multiple Navy training and testing activities over large areas of the ocean for a seven-year period; therefore, analyzing activities in multiple locations over multiple seasons produces the best estimate of impacts/take to inform the 2020 NWTT FSEIS/OEIS and for NMFS to use to make its determinations. The scale at which spatially explicit density models are structured is determined by the data collection method and the environmental variables that are used to build the model. A number of variables that are meaningful to marine mammal species, such as sea surface temperature, do not vary or affect species on a fine scale. Expecting fine scale resolution from the Navy's density database may force artificial granularity on species for which it is not biologically meaningful at the population level. Therefore, given the variables that determine when and where the Navy trains and tests and the resolution of the density data, the analysis of potential impacts cannot be scaled to specific habitat areas, but the information included is at the appropriate resolution and provides the Navy and NMFS with the information necessary to determine potential impacts/take for a population of animals. Chapter 3.4 (Marine Mammals) of the 2020 NWTT SFEIS/OEIS estimates what portion of impacts to each species are expected to occur within different regions in the Study Area. NMFS has reviewed and concurs with the Navy's analysis and level of detail provided given these restrictions.
Additionally, specific modeled locations are not disclosed in public documents because of national security concerns, and information regarding the exact location of sonar usage is classified, although classified exercise reports with this information are provided to NMFS staff with the required security clearance. Furthermore, the Navy requires large areas of sea and air space to support the tactics, techniques, and procedures needed for certain activities, and training in large areas also helps the Navy avoid observation by potential adversaries. Modern sensing technologies make training on a large scale without observation more difficult. A foreign military's continual observation of U.S. Navy training in predictable (
e.g.,
compiled and publicly disclosed) geographic areas and timeframes would enable foreign nations to gather intelligence and subsequently develop techniques, tactics, and procedures to potentially and effectively counter U.S. naval operations.
Still, the Navy's rulemaking/LOA application and the 2020 NWTT FSEIS/OEIS provide a significant level of information about the locations of specific activities (see,
e.g.,
Chapter 2 (Description of Proposed Action and Alternatives) and Appendix A (Activity Descriptions) of the FSEIS/OEIS), which NMFS has used in its analysis of Navy activities and their impacts to marine mammals in the NWTT Study Area. Chapter 2 of the 2020 NWTT FSEIS/OEIS also describes Standard Operating Procedures that may influence activity location. Additionally, this final rule, and Chapter 5 (Mitigation) and Appendix K (Geographic Mitigation Assessment) of the 2020 NWTT FSEIS/OEIS describe mitigation measures,
including in specific mitigation areas, that the Navy is required to implement during 2020-2027 NWTT activities. In addition to the above considerations, conservative assumptions are used in the quantitative assessment process, as described in the technical report titled
Quantifying Acoustic Impacts on Marine Mammals and Sea Turtles: Methods and Analytical Approach for Phase III Training and Testing
(U.S. Department of the Navy, 2018c), an analysis which NMFS has reviewed and concurs with. The Navy also implements conservative application of marine mammal behavioral response data in the development of behavioral response criteria, as described in the technical report titled
Criteria and Thresholds for U.S. Navy Acoustic and Explosive Effects Analysis (Phase III)
(U.S. Department of the Navy, 2017h), which NMFS has also reviewed and concurs with. (Both technical reports are available at
www.nwtteis.com.
)
Additionally, implementation of the adaptive management process under the Letters of Authorization issued under this final rule further ensures that the Navy does not exceed the level of authorized take. Finally, the Navy's classified exercise reports are required to include information regarding activities conducted and sound sources used within specific mitigation areas, which provides the sort of geographically-explicit information the commenter is referencing and may be used to inform the adaptive management process and future rules.
Comment 14:
A commenter stated that rather than using a fixed received level threshold for whether a take is likely to occur from exposure to mid-frequency sonar, the Navy has proposed a method for incorporating individual variation. Risk is predicted as a function of three parameters: (1) A basement value below which takes are unlikely to occur; (2) the level at which 50 percent of individuals would be taken; and (3) a sharpness parameter intended to reflect the range of individual variation. The commenter stated that even when parameters employed are based on the best available science, the implications of uncertainty in the values and biases and limitations in the model tend to lead to underestimation of the number of takes. The commenter asserts that data were incorrectly interpreted when calculating parameter values, resulting in a model that underestimates takes. The commenter states that errors included failure to recognize the difference between the mathematical basement plugged into the model, and the biological basement value, where the likelihood of observed and predicted takes becomes non-negligible; using the level where the probability of take was near 100 percent for the level where the probability of take was 50 percent; extrapolating values derived from laboratory experiments that were conducted on trained animals to wild animals without regard for the implications of training; and ignoring other available data, resulting in a further underestimation of takes. The commenter discusses several other points related to the development, interpretation, and application of the behavioral harassment thresholds used in prior Navy NWTT rules.
Response:
The commenter is referring to the Phase II behavioral criteria, which were utilized in the previous NWTT rulemaking (2015-2020). In Phase III for this rulemaking, the Navy and NMFS incorporated the best available science into new BRFs that are described in the technical report titled
Criteria and Thresholds for U.S. Navy Acoustic and Explosive Effects Analysis (Phase III)
(U.S. Department of the Navy, 2017a), available at
www.nwtteis.com.
NMFS reviewed and concurs with the Phase III behavioral criteria described in the technical report.
Comment 15:
A commenter recommends that NMFS (1) specify the total numbers of model-estimated Level A harassment (PTS) and mortality takes rather than reduce the estimated numbers of takes based on the Navy's post-model analyses, (2) include the model-estimated Level A harassment and mortality takes in its negligible impact determination analyses, and (3) authorize the model-estimated Level A harassment and mortality takes if the respective negligible impact determinations are able to be made and, if not, require the Navy to implement additional measures to mitigate such takes.
Another commenter stated that NMFS' post hoc adjustment for operational mitigation effectiveness is not a trivial or an abstract issue. It has the apparent effect of eliminating risk of mortality from explosives known to be of a power to kill marine mammals. Some experts have raised concerns that one Southern Resident killer whale mortality (whale L112) was caused by naval explosives or ordnance. NMFS should have made the Navy's approach transparent and explained the rationale for its acceptance of that approach. Its failure to do so has prevented the public from effectively commenting on its approach to this issue, in contravention of the APA, on a matter of obvious significance to the agency's core negligible impact findings. The commenter further states that, in estimating the number of instances of injury and mortality, NMFS makes two post hoc adjustments, significantly reducing the totals based on presumed animal avoidance and mitigation effectiveness. The commenter asserts that these two adjustments are arbitrary and non-conservative.
Response:
First, we note that no mortality or non-auditory injury from exposure to explosives was modeled for any species in the NWTT Study Area, so the post-modeling approach was not applied in relation to mortality. Regarding the reference to concerns about the killer whale mortality, the comment references vague and unsupported claims that the author of a news article received from interviewees questioning a NMFS report. NMFS is unaware of information supporting the claim that Navy sonar or explosive use has caused the death of a killer whale.
The consideration of marine mammal avoidance and mitigation effectiveness is integral to NMFS' and the Navy's overall analysis of impacts from sonar and explosive sources. NMFS has independently evaluated the method and agrees that it is appropriately applied to augment the model in the prediction and authorization of injury and mortality as described in the rule. Details of this analysis are provided in the Navy's 2018 technical report titled
Quantifying Acoustic Impacts on Marine Mammals and Sea Turtles: Methods and Analytical Approach for Phase III Training and Testing.
Detailed information on the mitigation analysis was included in the proposed rule, including information about the technical report, and NMFS disagrees with the commenters' suggestions that there was not enough information by which to evaluate the Navy's post-modeling calculations or that the methods are arbitrary or non-conservative.
Sound levels diminish quickly below levels that could cause PTS. Specifically, behavioral response literature, including the recent 3S studies (multiple controlled sonar exposure experiments on cetaceans in Norwegian waters) and SOCAL BRS studies (multiple cetacean behavioral response studies in Southern California), indicate that multiple species from different cetacean suborders do in fact avoid approaching sound sources by a few hundred meters or more, which would reduce received sound levels for individual marine mammals to levels below those that could cause PTS (see Appendix B of the
Criteria and Thresholds for U.S. Navy Acoustic and Explosive Impacts to Marine Mammals and Sea Turtles
Technical Report
(U.S. Department of the Navy, 2017) and Southall
et al.
(2019a)). The ranges to PTS for most marine mammal groups are within a few tens of meters and the ranges for the most sensitive group, the HF cetaceans, average about 200 m, to a maximum of 330 m in limited cases. For blue whales and other LF cetaceans, the range to PTS is 67 m for MF1 30 sec duration exposure, which is well within the mitigation zones for hull-mounted MFAS. Therefore, the anticipated avoidance to the distances discussed would greatly reduce the likelihood of impacts to hearing such as TTS and PTS. As discussed in the proposed rule, this final rule, and the Navy's report, animats in the Navy's acoustic effects model do not move horizontally or “react” to sound in any way. Accordingly, NMFS and the Navy's analysis appropriately applies a quantitative adjustment to the exposure results calculated by the model (which otherwise does not consider avoidance or mitigation).
As discussed in the Navy's report, the Navy's acoustic effects model does not consider procedural mitigations (
i.e.,
power-down or shut-down of sonars, or pausing explosive activities when animals are detected in specific zones adjacent to the source), which necessitates consideration of these factors in the Navy's overall acoustic analysis. Credit taken for mitigation effectiveness is extremely conservative. For example, if Lookouts can see the whole area, they get credit for it in the calculation; if they can see more than half the area, they get half credit; if they can see less than half the area, they get no credit. Not considering animal avoidance and mitigation effectiveness would lead to a great overestimate of injurious impacts. NMFS concurs with the analytical approach used,
i.e.,
we believe the estimated take by Level A harassment numbers represent the maximum number of these takes that are likely to occur and it would not be appropriate to authorize a higher number or consider a higher number in the negligible impact analysis.
The Navy assumes that Lookouts will not be 100 percent effective at detecting all individual marine mammals within the mitigation zones for each activity. This is due to the inherent limitations of observing marine species and because the likelihood of sighting individual animals is largely dependent on observation conditions (
e.g.,
time of day, sea state, mitigation zone size, observation platform) and animal behavior (
e.g.,
the amount of time an animal spends at the surface of the water). The Navy quantitatively assessed the effectiveness of its mitigation measures on a per-scenario basis for four factors: (1) Species sightability, (2) a Lookout's ability to observe the range to permanent threshold shift (for sonar and other transducers) and range to mortality (for explosives), (3) the portion of time when mitigation could potentially be conducted during periods of reduced daytime visibility (to include inclement weather and high sea-state) and the portion of time when mitigation could potentially be conducted at night, and (4) the ability for sound sources to be positively controlled (
e.g.,
powered down). The Navy's report clearly describes how these factors were considered, and it is not necessary to view the many tables of numbers generated in the assessment to evaluate the method. Further, this information is not readily available in a format that could be shared and it would take extensive work to provide the necessary description of this data.
The g(0) values used by the Navy for their mitigation effectiveness adjustments take into account the differences in sightability with sea state, and utilize averaged g(0) values for sea states of 1-4 and weighted as suggested by Barlow (2015). Using g(0) values is an appropriate and conservative approach (
i.e.,
it underestimates the protection afforded by the Navy's mitigation measures) for the reasons detailed in the technical report. For example, during line-transect surveys, there are typically two primary observers searching for animals. Each primary observer looks for marine species in the forward 90-degree quadrant on their side of the survey platform and scans the water from the vessel out to the limit of the available optics (
i.e.,
the horizon). Because Navy Lookouts focus their observations on established mitigation zones, their area of observation is typically much smaller than that observed during line-transect surveys. The mitigation zone size and distance to the observation platform varies by Navy activity. For example, during hull-mounted mid-frequency active sonar activities, the mitigation zone extends 1,000 yd from the ship hull. During the conduct of training and testing activities, there is typically at least one, if not numerous, support personnel involved in the activity (
e.g.,
range support personnel aboard a torpedo retrieval boat or support aircraft). In addition to the Lookout posted for the purpose of mitigation, these additional personnel observe for and disseminate marine species sighting information amongst the units participating in the activity whenever possible as they conduct their primary mission responsibilities. However, as a conservative approach to assigning mitigation effectiveness factors, the Navy elected to account only for the minimum number of required Lookouts used for each activity; therefore, the mitigation effectiveness factors may underestimate the likelihood that some marine mammals may be detected during activities that are supported by additional personnel who may also be observing the mitigation zone.
Although the Navy Acoustic Effects Model (NAEMO) predicted PTS takes from the NWTT activities, no mortality or non-auditory injuries were predicted by NAEMO. For all of the reasons above, NMFS considers the estimated and authorized take (that was adjusted for aversion and mitigation) appropriate, and that is what has been analyzed in the negligible impact analysis. Accordingly, we decline the commenter's recommendation to analyze and authorize the model-estimated PTS, as it is neither expected to occur nor authorized. Given that we have declined a re-evaluation based on the PTS numbers the commenter recommends, the suggestion that we would subsequently then assess whether additional mitigation were necessary to satisfy the negligible impact standard is inapplicable. However, we reiterate that even when the estimated take has been determined to have a negligible impact on the affected species or stocks, it is still necessary, as a separate matter, to identify measures that will effect the least practicable adverse impact on the affected species or stocks and their habitat and, as described elsewhere, we have done so for this rule.
Comment 16:
A commenter stated that while the cause remains unknown, the skinniness and emaciation of stranded gray whales associated with the current UME strongly suggests a decline in prey availability. A previous die-off in 1998-2000 of gray whales was associated with strong El Niño and La Niña events and a regime shift in the benthic prey base of the Bering Sea. For the scientific community, the present-day concern is that warming seas—caused by climate change—are reducing primary productivity in the whales' northern foraging range and that vanishing sea ice is constricting populations of ice-associated amphipods. If so, the die-off may be a “harbinger of things to come,” in the words of one NOAA ecologist, a diminished, more tenuous future for the species rather than a one- or two-year anomaly.
The commenter states that it is well established that animals already exposed to one stressor may be less capable of responding successfully to another; and that stressors can combine to produce adverse synergistic effects. Here, disruption in gray whale behavior can act adversely with the inanition caused by lack of food, increasing the risk of stranding and lowering the risk of survival in compromised animals. Further, starving gray whales may travel into unexpected areas in search of food—a likely contributing cause of some of the ship-strikes observed in recently stranded animals. NMFS estimates that the Navy's activities will cause as many as 43 takes of gray whales each year, including 15 cases of temporary hearing loss caused by underwater explosives, indicating the potential for adverse interactions with nutritionally-stressed animals.
The commenter states that in considering the effects of acoustic exposure on gray whales, NMFS must carefully consider the biological context of behavioral disruption in that species and evaluate the potential for severe consequences—including the clear potential mortality, which, in violation of the MMPA, is not authorized in the proposed rule.
Response:
This final rule includes 43 takes by Level B harassment of gray whales, less than one percent of the Eastern North Pacific stock, and no Level A harassment (PTS or non-auditory injury) of gray whales is anticipated or authorized. As discussed in the Analysis and Negligible Impact Determination section, the take by behavioral disturbance for any affected gray whale is expected to be at a moderate or low level and likely to occur on no more than one day within a year for any individual. Nonetheless, NMFS shares the commenter's concern for this stock given the UME and, as discussed in the Mitigation Measures section and elsewhere in this section, measures have been added since the proposed rule that are expected to further reduce the number and severity of the takes of gray whales. However, even if the impacts of the expected take was exacerbated by the compromised condition of a given individual, which could happen, there is no reason to expect that the level and severity of take anticipated to result from the Navy's activities would result in mortality as the commenter has suggested. Further, this gray whale stock is considered to be increasing.
Further, the commenter incorrectly states that NMFS did not include mortality of gray whales in the proposed rule. The proposed rule, and this final rule, include one mortality over the seven years covered by this rule, or 0.14 mortality annually, which has been analyzed in the context of its impacts on the stock in the Analysis and Negligible Impact Determination section. However, this mortality is associated with ship strike, not behavioral disturbance, and given the severity and magnitude of the authorized Level B harassment take reiterated above, the effects of the take would not accumulate to impact annual rates of recruitment or survival.
Comment 17:
A commenter stated that by itself, NMFS' avoidance adjustment effectively reduces the number of estimated auditory injuries by 95 percent, on the assumption that marine mammals initially exposed to three or four sonar transmissions at levels below those expected to cause permanent injury would avoid injurious exposures. While it is certainly true that some marine mammals will flee the sound, there are no data to inform how many would do so, let alone that 95 percent would move as expeditiously as the agency presumes. Marine mammals may remain in important habitat, and the most vulnerable individuals may linger in an area, notwithstanding the risk of harm; marine mammals cannot necessarily predict where an exercise will travel; and Navy vessels engaged in certain activities may move more rapidly than a marine mammal that is attempting to evacuate. Some commenters suggested that NMFS should not adjust for avoidance.
Response:
The consideration of marine mammals avoiding the area immediately around the sound source is provided in the Navy's 2018 technical report titled
Quantitative Analysis for Estimating Acoustic and Explosive Impacts to Marine Mammals and Sea Turtles
and additional discussion is provided in NMFS' response to Comment 15. As the commenter correctly articulates: “For avoidance, the Navy assumed that animals present beyond the range to onset PTS for the first three to four pings are assumed to avoid any additional exposures at levels that could cause PTS. That equated to approximately 5 percent of the total pings or 5 percent of the overall time active; therefore, 95 percent of marine mammals predicted to experience PTS due to sonar and other transducers were instead assumed to experience TTS.”
As discussed in the Navy report, animats in the Navy's acoustic effects model do not move horizontally or “react” to sound in any way, necessitating the additional step of considering animal avoidance of close-in PTS zones. NMFS independently reviewed this approach and concurs that it is fully supported by the best available science. Based on a growing body of behavioral response research, animals do in fact avoid the immediate area around sound sources to a distance of a few hundred meters or more depending upon the species. Avoidance to this distance greatly reduces the likelihood of impacts to hearing such as TTS and PTS, respectively. Specifically, the ranges to PTS for most marine mammal groups are within a few tens of meters and the ranges for the most sensitive group, the HF cetaceans, average about 200 m, to a maximum of 270 m in limited cases. NMFS continues to consider the adjustments for avoidance appropriate and declines the recommendation that the adjustment not be included in the estimation of take.
In regard to the comment about vessels moving faster than animals' ability to get out of the way, animals do not need to predict where an exercise will occur—in the vast majority of cases they can hear it coming. Further, the fact that vessels may move more rapidly than animals just makes it less likely that the animal would remain close enough to the source for the duration necessary to incur injury. NMFS and the Navy have appropriately considered animal movement in relation to testing and training activities and the commenter's observation does not necessitate any changes in our methods.
Comment 18:
A commenter recommends that NMFS ensure that its density estimates and abundance estimates used in the negligible impact determination analyses for harbor seals in Hood Canal, Washington Northern Inland Waters, and Southern Puget Sound are consistent, and if more recent abundance estimates from Navy monitoring efforts were used to inform the negligible impact determination analyses, use those same abundances estimates to inform its density estimates and re-estimate the numbers of takes accordingly. If NMFS intends to use the “instances of total takes as a percentage of the abundance” in the final rule, the commenter recommends that it ensure that the abundance estimates, total takes, and instances of total takes as a percentage of the abundance are accurately stipulated for all three metrics in the relevant tables.
Response:
NMFS has updated the abundance estimates for inland stocks of harbor seals using data from Jefferson
et al.
(2017) and Smultea
et al.
(2017) in this final rule and the same has been done in the 2020 NWTT FSEIS/OEIS. The Analysis and Negligible Impact Determination section reflects these latest abundance estimates and includes
a complete explanation for how they were calculated. The new information does not change the in-water density estimates, and therefore the number of takes did not change.
Comment 19:
A commenter stated that as it has done for every Navy offshore range in its third round of MMPA authorizations, NMFS finds, notwithstanding a long record, that the Navy's use of active sonar would not result in a single instance of serious injury or mortality in any cetacean species. In doing so, the agency is at pains to dismiss the scientific literature. It spends almost five columns of the
Federal Register
notice characterizing the leading scientific explanation for sonar-related injuries in beaked whales—maladaptive behavioral response—as a mere “hypothesis” about which more information is needed. In this, it elides the obvious fact that this “hypothesis” is supported by numerous papers along multiple lines of evidence, including forensic investigations, laboratory study of organ tissue, and theoretical work on dive physiology, and plainly constitutes best available science. And it concludes by opining that, even if the “hypothesis” were true, pathologies would occur only upon exposure “at very close range over a prolonged period of time,” which, it says, would not happen here. It provides no evidence for this conclusion, which should not come as a surprise since it is contradicted by the agency's own investigations into at least two prior mass stranding events.
The commenter stated that there is no question that sonar causes mortalities of beaked whales and other species, and that the severe injuries observed in beaked whales across multiple sonar-related mortality events occur independent of the animals' stranding. The commenter stated that NMFS' refusal to incorporate such impacts into its rulemaking violates the MMPA, which requires that decisions be based on best available science and which, consistent with the 1994 Amendments to the Act, implicitly sets a probability standard of potentiality for takes resulting in serious injury and mortality.
In a related comment, another commenter stated that while the Navy is aware of this correlation between sonar testing and stranded marine mammals, they choose to ignore the data and proceed with “hopeful” predictions that estimate no incidences of mortality or serious injury, despite contrary evidence from past use of sonar testing. The commenter states that the documented history of sonar related injuries and death cannot be ignored.
Response:
NMFS does not conclude that there is no possibility for mortality to occur as a result of the Navy's sonar activities, rather, we reason that consideration of all applicable information (the best available science) does not indicate that such mortality is reasonably likely to result from the Navy's activities within the seven-year span of the NWTT rule.
NMFS has acknowledged that it is possible for naval activities using hull-mounted tactical sonar to contribute to the death of marine mammals in certain circumstances via strandings resulting from behaviorally mediated physiological impacts or other gas-related injuries. In the proposed rule, NMFS discussed these potential causes and outlined the few cases where active naval sonar (in the United States or, largely, elsewhere) had either potentially contributed to or (as with the Bahamas example) been more definitively causally linked with marine mammal mass strandings (more than two animals). There have been no documented mass strandings of beaked whales in the NWTT Study area since stranding data began to be collected.
As discussed in the proposed rule and the Estimated Take of Marine Mammals section of this final rule, there are a suite of factors that have been associated with these specific cases of strandings directly associated with sonar (steep bathymetry, multiple hull-mounted platforms using sonar simultaneously, constricted channels, strong surface ducts,
etc.
) that are not present together in the NWTT Study Area and during the specified activities (and which the Navy takes care across the world not to operate under without additional monitoring). The number of incidences of strandings resulting from exposure to active sonar are few worldwide, there are no major training exercises utilizing multiple hull-mounted sonar in the NWTT Study Area, the overall amount of active sonar use is low relative to other Navy Study Areas, and there have not been any documented mass strandings of any cetacean species in the NWTT Study Area. Appropriately therefore, the Navy has not requested, and NMFS does not anticipate or authorize, incidental take by mortality of beaked whales or any other species as a result of sonar use.
Comment 20:
Some commenters stated that the Navy Acoustic Effects Model (NAEMO) has limitations as it does not consider social factors, and this is likely to result in the model underestimating takes (
i.e.,
since Southern resident killer whales travel in groups, one whale ignoring noise while another avoids it would result in separation of individuals). Thus, either all whales would respond at the threshold for the most sensitive individual present, or stress rather than avoidance in some or most individuals would be the response. Another commenter suggested that NMFS does not consider calving cycles and migration in the analysis.
In a related comment, a commenter stated that first, not only do takes occur at far greater distances than predicted by the Navy's risk model, the fact that larger areas are exposed to a given received level with increasing distance from the source further multiplies the number of takes. This implies takes of specific individuals will be of greater duration and be repeated more often, resulting in unexpectedly large cumulative effects. Second, corrections need to be made for bias, and corrections will need to be larger for species for which there are no data than for species for which there are poor data. Third, the greater range at which takes would occur requires more careful consideration of habitat-specific risks and fundamentally different approaches to mitigation.
Response:
The NAEMO brings together scenario simulations of the Navy's activities, sound propagation modeling, and marine mammal distribution (based on density and group size) by species or stock to model and quantify the exposure of marine mammals above identified thresholds for behavioral harassment, TTS, PTS, non-auditory injury, and mortality. It includes social factors (
e.g.,
group sizes) typical of the species modeled. The Southern Resident killer whale densities inherently consider group size over large areas. We expect that on many days, the Navy's impacts will not affect Southern Resident killer whales, while on days that Southern Resident killer whales are affected, multiple individuals may be impacted, given group size. That said, all Southern Resident killer whale takes are expected to be takes by Level B harassment (behavioral disturbance and TTS) only.
Regarding the commenter's assertion that NMFS and the Navy have mischaracterized either the size of the ensonified area or the number of animals that will be exposed, we disagree. As discussed in the technical report titled
Quantifying Acoustic Impacts on Marine Mammals and Sea Turtles: Methods and Analytical Approach for Phase III Training and Testing
(U.S. Department of the Navy, 2018) available at
www.nwtteis.com,
marine mammal density data are provided as a 10 × 10 km grid in which each cell has a mean density and
standard error. In the NAEMO, species densities are distributed into simulation areas. Sixty distributions that vary based on the standard deviation of the density estimates are run per season (warm and cool) for each species to account for statistical uncertainty in the density estimate. The NAEMO also uses accepted propagation models and incorporates extensive databases of physical environmental data to accurately predict acoustic propagation, as described in this same technical report. This includes modeling for potential impacts at distances far from a sound source. The energy from multiple exposures during an event (
e.g.,
multiple sonar pings) are accumulated to assess auditory impacts. Takes of individuals are accurately accounted for in the q
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