Taking and Importing Marine Mammals: Taking Marine Mammals Incidental to U.S. Navy Operations of Surveillance Towed Array Sensor System Low Frequency Active Sonar

DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

50 CFR Part 218

[Docket No. 160920860-7368-01]

RIN 0648-BG35

Taking and Importing Marine Mammals: Taking Marine Mammals Incidental to U.S. Navy Operations of Surveillance Towed Array Sensor System Low Frequency Active Sonar

AGENCY:

National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA), Commerce.

ACTION:

Proposed rule; request for comments.

SUMMARY:

NMFS has received a request from the U.S. Navy (Navy) for authorization to take marine mammals, by harassment, incidental to conducting operations of Surveillance Towed Array Sensor System (SURTASS) Low Frequency Active (LFA) sonar in areas of the world's oceans (with the exception of Arctic and Antarctic waters and certain geographic restrictions), from August 15, 2017, through August 14, 2022. The Navy's activities are considered military readiness activities pursuant to the Marine Mammal Protection Act (MMPA), as amended by the National Defense Authorization Act for Fiscal Year 2004 (FY 2004 NDAA). Pursuant to the MMPA, NMFS is requesting comments on its proposal to issue regulations to govern the incidental take of marine mammals by Level B harassment during the specified activity.

DATES:

Comments and information must be received no later than May 30, 2017.

ADDRESSES:

You may submit comments on this document, identified by NOAA-HQ-2017-0037, by either of the following methods:

Electronic Submission:

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

www.regulations.gov/#!docketDetail;D=NOAA-HQ-2017-0037

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

Mail:

Comments should be addressed to Jolie Harrison, Chief, Permits and Conservation Division, Office of Protected Resources, National Marine Fisheries Service. Physical comments should be sent to 1315 East-West Highway, Silver Spring, MD 20910.

Instructions:

NMFS is not responsible for comments sent by any other method, to any other address or individual, and may not consider comments received after the end of the comment period. Comments received electronically, including all attachments, must not exceed a 25-megabyte file size. Attachments to electronic comments will be accepted in Microsoft Word, Excel, or Adobe PDF formats only. To help NMFS process and review comments more efficiently, please use only one method to submit comments. All comments received are a part of the public record and will generally be posted to

www.regulations.gov

and

www.nmfs.noaa.gov/pr/permits/incidental/military

without change. All Personal Identifying Information (for example, name, address, etc.) voluntarily submitted by the commenter may be publicly accessible. Do not submit Confidential Business Information or otherwise sensitive or protected information.

FOR FURTHER INFORMATION CONTACT:

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

www.nmfs.noaa.gov/pr/permits/incidental/military.htm

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

SUPPLEMENTARY INFORMATION:

Background

Section 101(a)(5)(A) of the MMPA (16 U.S.C. 1361

et seq.

) directs the Secretary of Commerce (Secretary) to allow, upon request, the incidental, but not intentional, taking of small numbers of marine mammals in a specified geographical region for a period of up to five years, provided that certain findings are made and the necessary prescriptions are established.

The incidental taking of marine mammals shall be allowed if NMFS (through authority delegated by the Secretary) finds that the total taking by the specified activity during the specified time period will (1) have a negligible impact on the species or stock(s) and (2) not have an unmitigable adverse impact on the availability of the species or stock(s) for subsistence uses (where relevant). Further, the permissible methods of taking and other means of effecting the least practicable adverse impact on the species or stock and its habitat (

i.e.,

mitigation) must be prescribed. Requirements pertaining to the monitoring and reporting of such taking must also be set forth.

The allowance of incidental taking under section 101(a)(5)(A) requires promulgation of activity specific regulations. Subsequently, a Letter (or Letters) of Authorization (LOA) may be issued as governed by the regulations, provided that the level of taking will be consistent with the findings made for the total taking allowable under the specific regulations. The promulgation of regulations (with their associated prescribed mitigation, monitoring, and reporting) requires notice and opportunity for public comment.

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

The National Defense Authorization Act for Fiscal Year 2004 (FY 2004 NDAA) (Pub. L. 108-136) removed the “small numbers” and “specified geographical region” limitations indicated above and amended the definition of “harassment” as it applies to a “military readiness activity” to read as follows (Section 3(18)(B) of the MMPA): “(i) any act that injures or has the significant potential to injure a marine mammal or marine mammal stock in the wild” (Level A Harassment); “or (ii) any act that disturbs or is likely to disturb a marine mammal or marine mammal stock in the wild by causing disruption of natural behavioral patterns, including but not limited to migration, surfacing, nursing, breeding, feeding, or sheltering, to a point where such behavioral patterns are abandoned or significantly altered” (Level B Harassment). In addition, the FY 2004 NDAA amended the MMPA as it relates to military readiness activities and the Incidental Take Authorization (ITA) process such that “least practicable adverse impact” shall include consideration of personnel safety, practicality of implementation, and impact on the effectiveness of the military readiness activity.

Summary of Request

On August 26, 2016, NMFS received an application from the Navy requesting authorization for the take of individuals of 104 currently classified species or stocks of marine mammals (15 species of mysticete (baleen) whales, 60 species of odontocete (toothed) whales, and 29 species of pinnipeds (seals and sea lions)), by harassment, incidental to the use of SURTASS LFA sonar on a maximum of four U.S. Naval ships for routine training, testing, and military operations, hereafter called activities, in various areas of the Pacific, Atlantic, and Indian Oceans and the Mediterranean Sea from August 15,

2017 through August 14, 2022. These activities are classified as military readiness activities. The Navy states, and NMFS concurs, that these military readiness activities may incidentally take marine mammals present within the Navy's operation areas by exposing them to SURTASS LFA sonar at levels that constitute Level B harassment as defined above. The Navy requests authorization to take individuals of the 104 currently classified species or stocks of marine mammals by Level B Harassment. This rule may also cover the authorization of additional associated stocks of marine mammals not listed here, should one or more of the stocks identified in this rule be formally separated into multiple stocks, provided NMFS is able to confirm the necessary findings for the newly identified stocks. As discussed later in this document, takes due to SURTASS LFA sonar will be limited to Level B behavioral harassment. No takes by Level A harassment will be authorized as Level A harassment will be avoided through the implementation of the Navy's proposed mitigation measures. In previous rulemakings, NMFS authorized small numbers of Level A takes out of an abundance of caution even though Level A takes were not anticipated. However, there have been no Level A takes resulting from the past 14 years of SURTASS LFA sonar activities under previous rules. Additionally, the criteria and thresholds for assessing Level A harassment have been modified since prior rules. Under the new metrics, the potential for injury zone has been substantially reduced. Therefore, due to the small injury zones and the fact that mitigation measures would ensure that marine mammals would not receive levels associated with injury, the Navy has not requested authorization for Level A harassment takes, and NMFS is not proposing to authorize any takes by Level A harassment.

This is NMFS' fourth rulemaking for SURTASS LFA sonar activities under the MMPA. NMFS' current five-year regulations governing incidental takings incidental to SURTASS LFA sonar activities and the related Letters of Authorizations (LOA) expire on August 15, 2017. NMFS published the first SURTASS LFA sonar rule on July 16, 2002 (67 FR 46712), effective from August 2002 through August 2007. The second rule was published on August 21, 2007 (72 FR 46846), effective from August 16, 2007, through August 15, 2012. The third rule was published on August 20, 2012 (77 FR 50290), and is effective through August 14, 2017. For this proposed rulemaking, the Navy proposes to conduct the same types of sonar activities as they have conducted over the past 14 years with the following exception: The Navy proposes to transmit a maximum number of 255 hours of LFA sonar per vessel per year, as opposed to the previously authorized 432 hours of LFA sonar per vessel per year. Based on historical operating parameters, the average duty cycle (

i.e.,

the ratio of sound “on” time to total time) for SURTASS LFA sonar is normally 7.5 to 10 percent and the duty cycle is not expected to exceed 20 percent.

Description of the Specified Activities

Overview

The proposed action is Navy's continued employment of up to four SURTASS LFA sonar systems in the world's non-polar oceans, which is classified as a military readiness activity, from August 2017 to August 2022. Potential activities could occur in the Pacific, Atlantic, and Indian Oceans, and the Mediterranean Sea. The Navy will not operate SURTASS LFA sonar in Arctic and Antarctic waters. Additional geographic restrictions include maintaining SURTASS LFA sonar received levels below 180 dB re 1 µPa (root-mean-square (rms)) within 12 nautical miles (nmi) (22 kilometers (km)) of any land, and within the boundaries of designated Offshore Biologically Important Areas (OBIAs) during their effective periods (see below for more OBIA details).

Purpose and Background

The Navy's primary mission is to maintain, train, equip, and operate combat-ready naval forces capable of accomplishing American strategic objectives, deterring maritime aggression, and assuring freedom of navigation in ocean areas. This mission is mandated by Federal law in Section 5062 of Title 10 of the United States Code, which directs the Secretary of the Navy and Chief of Naval Operations (CNO) to ensure the readiness of the U.S. naval forces.

The Secretary of the Navy and the CNO have established that anti-submarine warfare (ASW) is a critical capability for achieving the Navy's mission, and it requires unfettered access to both the high seas and littoral environments to be prepared for all potential threats by maintaining ASW core competency. The Navy is challenged by the increased difficulty in locating undersea threats solely by using passive acoustic technologies due to the advancement and use of quieting technologies in diesel-electric and nuclear submarines. At the same time as the distance at which submarine threats can be detected decreases due to quieting technologies, improvements in torpedo and missile design have extended the effective range of these weapons.

One of the ways the Navy has addressed the changing requirements for ASW readiness was by developing SURTASS LFA sonar, which is able to reliably detect quieter and harder-to-find submarines at long range before these vessels can get within their effective weapons range to launch against their targets. SURTASS LFA sonar systems have a passive component (SURTASS), which is a towed line array of hydrophones used to detect sound emitted or reflected from submerged targets, and an active component (LFA), which is comprised of a set of acoustic transmitting elements. The active component detects objects by creating a sound pulse, or “ping” that is transmitted through the water and reflects off the target, returning in the form of an echo similar to echolocation used by some marine mammals to locate prey and navigate. SURTASS LFA sonar systems are long-range sensors that operate in the low-frequency (LF) band (

i.e.,

100-500 Hertz (Hz)). Because LF sound travels in seawater for greater distances than higher frequency sound, the SURTASS LFA sonar system would meet the need for improved detection and tracking of new-generation submarines at a longer range and would maximize the opportunity for U.S. armed forces to safely react to, and defend against, potential submarine threats while remaining a safe distance beyond a submarine's effective weapons range. Thus, the active acoustic component in the SURTASS LFA sonar is an important augmentation to its passive and tactical systems, as its long-range detection capabilities can effectively counter the threat to the Navy and national security interests posed by quiet, diesel submarines.

Dates and Duration

Due to uncertainties in the world's political climate, a detailed account of future operating locations and conditions for SURTASS LFA sonar use over the next five years cannot be predicted. However, for analytical purposes, a nominal annual deployment schedule and operational concept were developed based on actual SURTASS LFA sonar activities conducted since January 2003 and projected Fleet requirements (See Table 1).

Table 1—Example Annual Deployment Schedule for One Surveillance Vessel Using SURTASS LFA Sonar

On mission

Days

Off mission

Days

Transit

54

In-Port Upkeep

40

Active Activities

(Up to 255 transmission hours based on a nominal 7.5% duty cycle)

240

Regular Overhaul

31

Total Days on Mission

294

Total Days off Mission

71

Annually, each vessel is expected to spend approximately 54 days in transit and 294 days at sea conducting military readiness activities, which includes 240 days of active operations (amounting to 255 transmission hours based on a 7.5% duty cycle). Between missions, an estimated total of 71 days per year will be spent in port for upkeep and repair to maintain both the material condition of the vessel and its systems. The actual number and length of the individual missions within the 240 days are difficult to predict, but the maximum number of actual transmission hours per vessel per year will not exceed 255 hours.

As noted above, this would be the fourth continuous such authorization for the Navy's SURTASS LFA sonar activities. The Navy's current rule and LOA expire after August 14, 2017. Therefore, the Navy has requested MMPA rulemaking and will request annual LOAs for its SURTASS LFA sonar activities effective from August 15, 2017 through August 14, 2022, to take marine mammals incidental to the activities of up to four SURTASS LFA sonar systems. Subsequent LOA applications would be submitted annually throughout the remaining years of the new rule.

Potential SURTASS LFA Sonar Operational Areas

Figure 1 depicts the potential areas of activities for SURTASS LFA sonar. In areas within 12 nmi from any shorelines (coastal exclusion areas) and in areas identified as OBIAs, SURTASS LFA sonar would be operated such that received levels of LFA sonar are below 180 dB re 1 μPa rms sound pressure level (SPL). This restriction would be observed year-round for coastal exclusion areas and during periods of biological importance for OBIAs, but these areas are not depicted in Figure 1 as these areas are not visible at the map scale. Based on the Navy's current operational requirements, potential activities for SURTASS LFA sonar vessels from August 2017 through August 2022 would include areas located in the Pacific, Atlantic, and Indian Oceans as well as the Mediterranean Sea.

EP27AP17.000

The Navy will not operate SURTASS LFA sonar pursuant to this rule in polar regions (

i.e.,

Arctic and Antarctic waters) of the world (see shaded areas in Figure 1). The Arctic Ocean, the Bering Sea (including Bristol Bay and Norton Sound), portions of the Norwegian, Greenland, and Barents Seas north of 72° North (N) latitude, plus Baffin Bay, Hudson Bay, and the Gulf of St. Lawrence would be non-operational areas for SURTASS LFA sonar. In the

Antarctic, the Navy will not conduct SURTASS LFA activities in areas south of 60° South (S) latitude. The Navy has excluded polar waters from operational planning because of the inherent inclement weather conditions and the navigational and operational (equipment) danger that icebergs pose to SURTASS LFA sonar vessels.

The Navy must anticipate, or predict, where they have to operate in the next five years for the MMPA rulemaking. Naval forces are presently operating in several areas strategic to U.S. national and international interests. National security needs may dictate that many of these operational areas will be close to ports and choke points, such as entrances to straits, channels, and canals. It is anticipated that many future naval conflicts are likely to occur within littoral or coastal areas. However, it is infeasible for the Navy to analyze all potential global mission areas for all species and stocks for all seasons. Instead, the Navy projects where it intends to use SURTASS LFA sonar for the next five-year authorization period based on today's political climate and provides NMFS with take estimates for marine mammal stocks in the proposed areas of activity. NMFS believes that this provides sufficient coverage for worldwide SURTASS LFA sonar activities, as specific take numbers are requested on an annual basis in applications for LOAs, subject to an annual cap of 12 percent per stock.

For this fourth rulemaking, the Navy modeled and analyzed 26 representative mission areas in the Pacific, Atlantic, and Indian Oceans and the Mediterranean Sea to represent the acoustic regimes and marine mammal species/stocks that may be encountered during worldwide SURTASS LFA sonar activities (see Table 2). They are comprised of the following modeled areas: East of Japan; north Philippine Sea; west Philippine Sea; offshore Guam; Sea of Japan; East China Sea; South China Sea; Offshore Japan (two locations: 25° to 40° N and 10° to 25° N); Hawaii North; Hawaii South; Offshore Southern California; western north Atlantic; eastern North Atlantic; Mediterranean Sea; Arabian Sea; Andaman Sea; Panama Canal; northeast Australia; northwest Australia; northeast of Japan; southern Gulf of Alaska; southern Norwegian Basin (between Iceland and Norway); western North Atlantic (off of Virginia/Maryland); Labrador Sea; and Sea of Okhotsk. Since the Navy cannot forecast the location of its operations, annual requests will be submitted to NMFS that will include specific mission areas and modeling locations for each year's activities. For more details of the impact analysis, see Appendix B in the DSEIS/SOEIS.

Table 2—Potential SURTASS LFA Sonar Activity Areas That the Navy Modeled for the DSEIS/OEIS (DoN, 2016

a

) and the MMPA Rulemaking/LOA Application

Modeled site

Location

(latitude/longitude of center of

modeling area)

Modeled site

Location

(latitude/longitude of center of

modeling area)

East of Japan

38° N., 148° E.

Eastern North Atlantic

56.4° N., 10° W.

North Philippine Sea

29° N., 136° E.

Mediterranean Sea

39° N., 6° E.

West Philippine Sea

22° N., 124° E.

Arabian Sea

14°N., 65° E.

Offshore Guam (Mariana Islands Range Complex, outside Mariana Trench)

11° N., 145° E.

Andaman Sea

7.5° N., 96° E.

Sea of Japan

39° N., 132° E.

Panama Canal

5° N., 81° W.

East China Sea

26° N., 125° E.

Northeast Australia

23° S., 155° E.

South China Sea

14° N., 114° E.

Northwest Australia

18° S., 110° E.

Offshore Japan 25° to 40° N

30° N., 165° E.

Northeast of Japan

52° N., 163° E.

Offshore Japan 10° to 25° N

15° N., 165° E.

Southern Gulf of Alaska

51° N., 150° W.

Hawai'i North

25° N., 158° W.

Southern Norwegian Basin (between Iceland and Norway)

65° N., 0°

Hawaii South

19.5° N., 158.5° W.

Western North Atlantic (off of Virginia/Maryland)

39.6° N., 71.6° W.

Offshore Southern California

32° N., 120° W.

Labrador Sea

57° N., 50° W.

Western North Atlantic (off Florida)

29° N., 76° W.

Sea of Okhotsk

51° N., 150° E.

The use of the SURTASS LFA sonar system during at-sea activities would result in acoustic stimuli from the generation of sound or pressure waves in the water at or above levels that NMFS has determined would result in take of marine mammals under the MMPA. This is the principal means of marine mammal taking associated with these military readiness activities and the Navy has requested authorization to take marine mammals by Level B harassment. At no point are there expected to be more than four systems in use, and thus this proposed rule analyzes the impacts on marine mammals due to the deployment of up to four SURTASS LFA sonar systems for a five-year period between August 2017 and August 2022.

In addition to the use of active acoustic sources, the Navy's activities include the operation and movement of vessels. This document also analyzes the effects of this aspect of the activities. However, NMFS does not anticipate takes of marine mammals to result from ship strikes from any of the four SURTASS LFA vessels because each vessel moves at a relatively slow speed, especially when towing the SURTASS and LFA sonar systems, and for a relatively short period of time. Combined with the use of mitigation measures as noted below, it is likely that any marine mammal would be able to avoid the surveillance vessels.

Detailed Description of the Specified Activities

Description of SURTASS LFA Sonar

SONAR is an acronym for Sound Navigation and Ranging, and its definition includes any system (biological or mechanical) that uses underwater sound, or acoustics, for detection, monitoring, and/or communications. Active sonar is the transmission of sound energy for the purpose of sensing the environment by interpreting features of received signals. Active sonar detects objects by creating a sound pulse, or “ping” that is transmitted through the water and reflects off the target, returning in the form of an echo. Passive sonar detects

the transmission of sound waves created by an object.

As mentioned previously, the SURTASS LFA sonar system is a long-range, all-weather LF sonar (operating between 100 and 500 Hertz (Hz)) system that has both active and passive components. LFA, the active system component (which allows for the detection of an object that is not generating noise), is comprised of source elements (called projectors) suspended vertically on a cable beneath the surveillance vessel. The projectors produce an active sound pulse by converting electrical energy to mechanical energy by setting up vibrations or pressure disturbances within the water to produce a ping. The Navy uses LFA as an augmentation to the passive SURTASS operations when passive system performance is inadequate. SURTASS, the passive part of the system, uses hydrophones (

i.e.,

underwater microphones) to detect sound emitted or reflected from submerged targets, such as submarines. The SURTASS hydrophones are mounted on a horizontal line array that is towed behind the surveillance vessel. The Navy processes and evaluates the returning signals or echoes, which are usually below background or ambient sound level, to identify and classify potential underwater targets.

LFA Active Component

The active component of the SURTASS LFA sonar system consists of up to 18 projectors suspended beneath the surveillance vessel in a vertical line array. The SURTASS LFA sonar projectors transmit in the low-frequency band (between 100 and 500 Hz). The source level of an individual projector in the SURTASS LFA sonar array is approximately 215 dB re: 1 μPa at 1 m or less (Sound pressure is the sound force per unit area and is usually measured in micropascals (μPa), where one Pascal (Pa) is the pressure resulting from a force of one newton exerted over an area of one square meter. The commonly used reference pressure level in underwater acoustics is 1 μPa at 1 m, and the units for source level are decibels (dB) re: 1 μPa at 1 m). Because of the physics involved in acoustic beamforming (

i.e.,

a method of mapping noise sources by differentiating sound levels based upon the direction from which they originate) and sound transmission loss processes, the SURTASS LFA sonar array cannot have a SPL higher than the SPL of an individual projector.

The SURTASS LFA sonar acoustic transmission is an omnidirectional beam (a full 360 degrees (°)) in the horizontal plane. The LFA sonar system also has a narrow vertical beam that the vessel's crew can steer above or below the horizontal plane. The typical SURTASS LFA sonar signal is not a constant tone, but rather a transmission of various signal types that vary in frequency and duration (including continuous wave (CW) and frequency-modulated (FM) signals). A complete sequence of sound transmissions, also referred to by the Navy as a “ping” or a wavetrain, can be as short as six seconds (sec) or last as long as 100 sec, with an average length of 60 sec. Within each ping, the duration of any continuous frequency sound transmission is no longer than 10 sec and the time between pings is typically from six to 15 minutes (min). Based on the Navy's historical operating parameters, the average duty cycle (

i.e.,

the ratio of sound “on” time to total time) for LFA sonar is normally 7.5 to 10 percent and the duty cycle is not expected to exceed 20 percent.

Compact LFA Active Component

In addition to the LFA sonar system deployed on the USNS IMPECCABLE, the Navy developed a compact LFA (CLFA) sonar system now deployed on its three smaller surveillance vessels (

i.e.,

the USNS ABLE, EFFECTIVE, and VICTORIOUS). In the application, the Navy indicates that the operational characteristics of the active component CLFA sonar are comparable to the existing LFA systems and that the potential impacts from CLFA will be similar to the effects from the existing LFA sonar system. The CLFA sonar system consists of smaller projectors that weigh 142,000 lbs (64,410 kilograms (kg)), which is 182,000 lbs (82,554 kg) less that the mission weight of the LFA projectors on the USNS IMPECCABLE. The CLFA sonar system also consists of up to 18 projectors suspended beneath the surveillance vessel in a vertical line array and the CLFA sonar projectors transmit in the low-frequency band (also between 100 and 500 Hz) with the same duty cycle as described for LFA sonar. Similar to the active component of the LFA sonar system, the source level of an individual projector in the CLFA sonar array is approximately 215 dB re: 1 μPa or less.

For the analysis in this rulemaking, NMFS will use the term LFA to refer to both the LFA sonar system and/or the CLFA sonar system, unless otherwise specified.

SURTASS Passive Component

The passive component of the SURTASS LFA sonar system consists of a SURTASS Twin-line (TL-29A) horizontal line array mounted with hydrophones. The Y-shaped array is 1,000 ft (305 m) in length and has an operational depth of 500 to 1,500 ft (152.4 to 457.2 m). The SURTASS LFA sonar vessel typically maintains a speed of at least 3.4 mph (5.6 km/hr; 3 knots (kts)) to tow the array astern of the vessel in the correct horizontal configuration.

High-Frequency Active Sonar

Although technically not part of the SURTASS LFA sonar system, the Navy also proposes to use a high-frequency sonar system, called the High Frequency Marine Mammal Monitoring sonar (HF/M3 sonar), to detect and locate marine mammals within the SURTASS LFA sonar activity areas and mitigation and buffer zones, as described later in this proposed rule. This enhanced commercial fish-finding sonar, mounted at the top of the SURTASS LFA sonar vertical line array, has a source level of 220 dB re: 1 μPa at 1 m with a frequency range from 30 to 40 kilohertz (kHz). The duty cycle is variable, but is normally below three to four percent and the maximum pulse duration is 40 milliseconds. The HF/M3 sonar has four transducers with 8° horizontal and 10° vertical beamwidths, which sweep a full 360° in the horizontal plane every 45 to 60 sec with a maximum range of approximately 1.2 mi (2 km).

Vessel Specifications

The Navy proposes to deploy the SURTASS LFA sonar system on a maximum of four U.S. Naval ships: the USNS ABLE (T-AGOS 20), the USNS EFFECTIVE (T-AGOS 21), the USNS IMPECCABLE (T-AGOS 23) and the USNS VICTORIOUS (T-AGOS 19).

The USNS ABLE, EFFECTIVE, and VICTORIOUS, are twin-hulled ocean surveillance ships. Each vessel has a length of 235 feet (ft) (71.6 meters (m)); a beam of 93.6 ft (28.5 m); a maximum draft of 25 ft (7.6 m); and a full load displacement of 3,396 tons (3,451 metric tons). A twin-shaft diesel electric engine provides 3,200 horsepower (hp), which drives two propellers.

The USNS IMPECCABLE, also a twin-hulled ocean surveillance ship, has a length of 281.5 ft (85.8 m); a beam of 95.8 ft (29.2 m); a maximum draft of 26 ft (7.9 m); and a full load displacement of 5,368 tons (5,454 metric tons). A twin-shaft diesel electric engine provides 5,000 hp, which drives two propellers.

The operational speed of each vessel during sonar activities will be approximately 3.4 miles per hour (mph) (5.6 km per hour (km/hr); 3 knots (kt)) and each vessel's cruising speed outside

of sonar activities would be a maximum of approximately 11.5 to 14.9 mph (18.5 to 24.1 km/hr; 10 to 13 kts). During sonar activities, the SURTASS LFA sonar vessels will generally travel in straight lines or in oval-shaped (

i.e.,

racetrack) patterns depending on the operational scenario.

Each vessel also has an observation area on the bridge from where lookouts will monitor for marine mammals before and during LFA sonar activities. When stationed on the bridge of the USNS ABLE, EFFECTIVE, or VICTORIOUS, the lookout's eye level will be approximately 32 ft (9.7 m) above sea level providing an unobstructed view around the entire vessel. For the USNS IMPECCABLE, the lookout's eye level will be approximately 45 ft (13.7 m) above sea level.

Notice of Receipt Comments and Responses

On October 21, 2016, NMFS published a notice of receipt (NOR) of an application for rulemaking in the

Federal Register

(81 FR 72782) and requested comments and information from the interested public for 30 days. During the 30-day comment period, which ended on November 21, 2016, NMFS received one comment from an environmental non-governmental organization. This comment stated that the Navy should address several shortcomings in the application such as: (1) Update the information of the impacts of LFA sonar on sensitive federal protected species and their critical habitat; (2) increase the number of offshore biological important areas and expand others to include marine mammal critical habitat; (3) increase current buffer zones to reduce impacts of LFA sonar; (4) update the scientific information of the impact of LFA sonar on marine mammals; (5) provide an analysis of negative effects for information-poor populations; (6) analyze cumulative impacts of LFA sonar, including the synergistic/additive effects of climate change; and (7) include additional mitigation measures to reduce LFA sonar impacts.

The Navy addressed impacts to endangered and threatened species and critical habitat in their application, and the Navy and NMFS' Office of Protected Resources Permits and Conservation Division are currently in consultation with NMFS' Office of Protected Resources ESA Interagency Consultation Division. Consistent with the 1989 preamble for NMFS' implementing regulations (54 FR 40338, September 29, 1989), the impacts from past and ongoing anthropogenic activities are reflected in the environmental baseline (

e.g.,

these impacts are reflected in the density/distribution and status of the species, population size and growth rate, and ambient noise). The reader is also referred to the 2016 DSEIS/SOEIS for more detailed information, including the cumulative impacts and climate change analyses. As noted in the Navy's application, as well as the DSEIS/SOEIS (for which NMFS is a cooperating agency with the Navy for purposes of adopting the DSEIS for this action and in this proposed rule, the number of biologically important areas under consideration have been expanded (commenter noted there are only 22 OBIAs, but there are 28 included in the application and DSEIS/SOEIS). NMFS has addressed the issue of increased buffer zones in previous rulemaking, and it was determined that this was not warranted (see 77 FR 50290, August 20, 2012, Comment 36 Response, and response to comment NRDC-17 of the Navy's 2012 FSEIS/SOEIS for rationale for the additional 1 km buffer). Reanalysis of the matter in this rule confirms this determination. Required buffer zones imposed by NMFS on the Navy's SURTASS LFA sonar include an additional 1 km buffer zone around the Navy's LFA Mitigation Zone and an additional 1 km buffer zone seaward of any OBIA during the time of biological importance. Implementation of the additional 1 km buffer zone will ensure that no marine mammals are exposed to an SPL greater than approximately 174 dB re: 1 μPa, which is below levels for which most marine mammals are anticipated to experience onset of TTS or PTS, and therefore limits potential takes to lower-level Level B behavioral harassment. Lastly, NMFS and Navy evaluated ways to address data-poor scenarios and potential additional mitigation measures as part of the rulemaking process and ongoing adaptive management, which is described in more detail below.

The Marine Mammal Commission (MMC) did not submit comments in response to the NOR, but had previously submitted comments to the Navy and NMFS in response to the Navy's DSEIS/OEIS, and stated that these comments would also suffice as their comments on the Navy's application. The MMC made recommendations to use the best available science plus some measure of uncertainty (

e.g.,

mean plus two standard deviations, mean plus the coefficient of variation, the upper limit of the confidence level) in instances where density data were extrapolated due to data not being available; that the Navy make its Marine Species Density Database (NMSDD) available to the public as soon as possible, specify how density estimates were derived, and what statistic (

e.g.,

mean, median, maximum) was used when multiple sources are referenced; expressed concern regarding the Navy's use of the single ping equivalent (SPE) metric (discussed in more detail below), and recommended that the Navy either use the SPL or sound exposure level (SEL) metric in assessment of behavioral risk from exposure to SURTASS LFA sonar, or use behavior response metrics and thresholds based on Finneran and Jenkins (2012); recommended that the Navy amend its DSEIS/SOEIS to specify the numbers of marine mammals that could be taken by Level A and B harassment incidental to operating SURTASS LFA sonar, rather than providing the percentages of each stock for such takes; requested further clarification in regard to whether there were zero Level A takes modeled, or if Level A takes were reduced to zero with mitigation applied; and expressed agreement with the proposed expansion of five OBIAs and the addition of six new OBIAs, but requested additional information on the evaluation for determining that other areas did not meet the criteria for designation as OBIAs.

Regarding the NMSDD, all data sources that go into the database are cited so they can be obtained. Some of the data sources are proprietary, so the Navy is unable to provide the NMSDD in GIS shapefile format because they only have a license for the Navy. NMFS notes that the single ping equivalent (SPE) has been used in each of the previous rulemakings and NMFS continues to believe the use of this metric is appropriate for assessing behavioral responses for SURTASS LFA sonar because it is a conservative estimate that accounts for the increased potential for behavioral responses due to repeated exposures by adding 5 x log10 (number of pings) to each 1-dB received level (RL) increment, and sums these across all dB levels to determine the dB SPE for each modeled animal (

i.e.,

SPE is a cumulative metric which accounts for not only the level of exposure but also the duration of exposure). The behavior response data used to derive Finneran and Jenkins (2012) thresholds were from mid-frequency sources, while the data used to derive the behavioral thresholds for SURTASS LFA were specifically from studies using the actual source. Therefore, NMFS feels they are more appropriate to apply to SURTASS LFA sonar. Also, as in previous rulemakings, the proposed rule does not specify the

number of marine mammals that may be taken in the proposed locations because these numbers are determined annually through various inputs such as mission location, mission duration, and season of operation. As with previous rulemakings, this proposed rule analyzes a maximum of 12 percent takes by Level B harassment per stock annually, and the Navy will use the 12 percent limit to guide its mission planning and annual LOA applications as described in more detail below. We also note that the analysis for this rulemaking used the updated thresholds per the NMFS 2016 Acoustic Technical Guidance, and based on this analysis, NMFS and the Navy believe that it is unlikely that Level A Harassment takes are likely to occur, and therefore none are proposed to be authorized. Lastly, in regard to OBIAs, we continue to work with the Navy in reviewing and analyzing OBIAs as part of adaptive management. As described in the 2012 rulemaking as well as the Navy's 2016 application and DSEIS/SOEIS, as new information becomes available, areas are re-evaluated to determine if any areas should be added or expanded. NMFS has also evaluated the recommendations in a white paper written by NMFS scientists (discussed in detail below).

Description of Marine Mammals in the Area of the Specified Activities

One hundred and four (104) currently classified marine mammal species or stocks have confirmed or possible occurrence within potential SURTASS LFA activity areas in certain areas of the Pacific, Atlantic, and Indian Oceans and the Mediterranean Sea. Fifteen (15) species of baleen whales (mysticetes), 60 species of toothed whales, dolphins, or porpoises (odontocetes), and 29 species of seals or sea lions (pinnipeds) could be affected by SURTASS LFA sonar activities. Multiple stocks of some species are affected, and independent assessments are conducted to make the necessary findings and determinations for each of these.

There are 20 marine mammal species under NMFS' jurisdiction that are listed as endangered or threatened under the Endangered Species Act (ESA; 16 U.S.C. 1531

et seq.

) with confirmed or possible occurrence in potential activity areas for SURTASS LFA sonar. Marine mammal species under NMFS' jurisdiction listed as endangered include: The blue whale (

Balaenoptera musculus

); fin whale (

Balaenoptera physalus

); sei whale (

Balaenoptera borealis

); the Arabian Sea, Cape Verde Islands/Northwest Africa, Central America, and Western North Pacific distinct population segments (DPS) of humpback whale (

Megaptera novaeangliae

); bowhead whale (

Balaena mysticetus

); North Atlantic right whale (

Eubalaena glacialis

); North Pacific right whale (

Eubalaena japonica

); southern right whale (

Eubalaena australis

); Western North Pacific population of gray whale (

Eschrichtius robustus

); sperm whale (

Physeter macrocephalus

); the Cook Inlet stock of beluga whale (

Delphinapterus leucas

); the main Hawaiian Islands Insular DPS of false killer whale (

Psuedorca crassidens

); the Southern Resident population of Killer whale (

Orca orcinus

); the Western DPS of the Steller sea lion (

Eumetopias jubatus

); Mediterranean monk seal (

Monachus monachus

); and Hawaiian monk seal (

Monachus schauinslandi

). Marine mammal species under NMFS' jurisdiction listed as threatened include: The Guadalupe fur seal (

Arctocephalus townsendi

); the Okhotsk ringed seal (

Pusa hispida ochotensis

); the Okhotsk DPS of Pacific bearded seal (

Erignathus barbatus nauticus

); the southern DPS of the spotted seal (

Phoca largha

); and the Mexico DPS of humpback whale (

Megaptera novaeangliae

). Additionally, the Gulf of Mexico subspecies of the Bryde's whale has recently been proposed for listing under the ESA as endangered. The aforementioned threatened and endangered marine mammal species also are depleted under the MMPA.

Three of the 104 species or stocks with potential occurrences within possible SURTASS LFA activity areas are considered depleted under the MMPA but are not ESA-listed. They are: The Eastern (Loughlin's) Steller sea lion (

Eumetopias jubatus monteriensis

); the Pribilof Island/Eastern Pacific stock of northern fur seal (

Callorhinus ursinus

); and the arctic ringed seal (

Pusa hispida hispida

).

Chinese river dolphins (

Lipotes vexillifer

) and vaquita (

Phocoena sinus

) do not have stocks designated within potential SURTASS LFA sonar operational areas (see Potential SURTASS LFA Operational Areas section). The distribution of the Chinese river dolphin is limited to the main channel of a river section between the cities of Jingzhou and Jiangyin. The vaquita's distribution is restricted to the upper portion of the northern Gulf of California, mostly within the Colorado River delta. Based on the extremely rare occurrence of these species in the Navy's operational areas and coastal standoff range (

i.e.,

distance of 22 km (13 mi; 12 nmi) from land), take of Chinese river dolphins or vaquita is not considered a reasonable likelihood; therefore these species are not addressed further in this document.

The U.S. Fish and Wildlife Service (USFWS) is responsible for managing the following marine mammal species: Southern sea otter (

Enhydra lutris

), polar bear (

Ursus maritimus

), walrus (

Odobenus rosmarus

), west African manatee (

Trichechus senegalensis

), Amazonian manatee (

Trichechus inunguis

), west Indian manatee (

Trichechus manatus

), and dugong (

Dugong dugon

). None of these species occur in geographic areas that would overlap with SURTASS LFA sonar operational areas. Therefore, the Navy has determined that SURTASS LFA sonar activities would have no effect on the endangered or threatened species or the critical habitat of the ESA-listed species under the jurisdiction of the USFWS. These species are not considered further in this notice.

Tables 3 through 28 (below) summarize the abundance, status under the ESA, and density estimates of the marine mammal species and stocks that have confirmed or possible occurrence within 26 SURTASS LFA sonar operating areas in the Pacific, Indian, and Atlantic Oceans and Mediterranean Sea. To accurately assess the potential effects of worldwide SURTASS LFA sonar activities, the Navy modeled 26 representative sites based on the Navy's current assessment of current and future requirements or threats.

Table 3—Abundance and Density Estimates for the Marine Mammal Species, Species Groups, and Stocks Associated With Mission Area 1, the Sea of Japan

[Summer season]

Species

Stock name

1

Stock

abundance

2

Density

(animals/km

2

)

3

ESA

status

4

Blue whale

WNP

9,250

5

NA

EN

Fin whale

WNP

9,250

0.0002

EN

Sei whale

NP

7,000

0.0006

EN

Bryde's whale

WNP

20,501

0.0006

NL

Minke whale

WNP “O” Stock

25,049

0.0022

NL

North Pacific right whale

WNP

922

NA

EN

Humpback whale

WNP

1,328

0.00036

EN

Sperm whale

NP

102,112

0.00123

EN

Harbor porpoise

WNP

31,046

0.0190

NL

Baird's beaked whale

WNP

8,000

0.0029

NL

Cuvier's beaked whale

WNP

90,725

0.0031

NL

Ginkgo-toothed beaked whale

NP

22,799

0.0005

NL

Hubbs beaked whale

NP

22,799

0.0005

NL

False killer whale

WNP—Pelagic

16,668

0.0036

NL

Pygmy killer whale

WNP

30,214

0.0021

NL

Short-finned pilot whale

WNP

53,608

0.0128

NL

Risso's dolphin

WNP

83,289

0.0097

NL

Short-beaked common dolphin

WNP

3,286,163

0.0761

NL

Killer whale

WNP

12,256

0.0001

NL

Common bottlenose dolphin

WNP

168,791

0.0171

NL

Pantropical spotted dolphin

WNP

438,064

0.0259

NL

Striped dolphin

WNP

570,038

0.0111

NL

Spinner dolphin

WNP

1,015,059

0.00083

NL

Pacific white-sided dolphin

NP

931,000

0.0082

NL

Rough-toothed dolphin

WNP

145,729

0.0059

NL

Kogia

spp

WNP

350,553

0.0031

NL

Stejneger's beaked whale

WNP

8,000

0.0005

NL

1

NP = north Pacific; WNP = western north Pacific.

2

Refer to Table 3-2 of the Navy's application for literature references associated with abundance estimates presented in this table.

3

Refer to Table 3-2 of the Navy's application for literature references associated with density estimates presented in this table.

4

ESA Status: EN = Endangered; T = Threatened; NL = Not Listed.

5

NA in the Density column indicates that although the stock or DPS occurs in that mission area, it is not expected to occur during the season modeled.

Table 4—Abundance and Density Estimates for the Marine Mammal Species, Species Groups, and Stocks Associated With Mission Area 2, North Philippine Sea Operational Area

[Fall season]

Species

Stock name

1

Abundance

2

Density

(animals/Km

2

)

3

ESA

status

4

Bryde's whale

WNP

20,501

0.0006

NL

Minke whale

WNP “O” Stock

25,049

0.0044

NL

North Pacific right whale

WNP

922

5

NA

EN

Blue whale

WNP

9,250

.00001

EN

Fin whale

WNP

9,250

NA

EN

Humpback whale

WNP

1,328

.00089

EN

Omura's whale

WNP

1,800

.00006

NL

Sperm whale

NP

102,112

0.00123

EN

Common bottlenose dolphin

WNP

168,791

0.0146

NL

Cuvier's beaked whale

WNP

90,725

0.0054

NL

Blainville's beaked whale

WNP

8,032

0.0005

NL

Ginkgo-toothed beaked whale

NP

22,799

0.0005

NL

Killer whale

WNP

12,256

0.00009

NL

False killer whale

WNP—Pelagic

16,668

0.0029

NL

Pygmy killer whale

WNP

30,214

0.0021

NL

Melon-headed whale

WNP

36,770

0.00428

NL

Short-finned pilot whale

WNP

53,608

0.0153

NL

Risso's dolphin

WNP

83,289

0.0106

NL

Short-beaked common dolphin

WNP

3,286,163

0.0562

NL

Fraser's dolphin

WNP

220,789

0.0069

NL

Kogia

spp

WNP

350,553

0.0031

*

Long-beaked common dolphin

WNP

279,182

0.1158

NL

Longman's beaked whale

WNP

4,571

0.00025

NL

Pantropical spotted dolphin

WNP

438,064

0.0137

NL

Striped dolphin

WNP

570,038

0.0329

NL

Spinner dolphin

WNP

1,015,059

0.00083

NL

Pacific white-sided dolphin

NP

931,000

NA

NL

Rough-toothed dolphin

WNP

145,729

0.0059

NL

1

NP = north Pacific; WNP = western north Pacific.

2

Refer to Table 3-2 of the Navy's application for literature references associated with abundance estimates presented in this table.

3

Refer to Table 3-2 of the Navy's application for literature references associated with density estimates presented in this table.

4

ESA Status: EN = Endangered; T = Threatened; NL = Not Listed.

5

NA in the Density column indicates that although the stock or DPS occurs in that mission area, it is not expected to occur during the season modeled.

Table 5—Abundance and Density Estimates for the Marine Mammal Species, Species Groups, and Stocks Associated With Mission Area 3, West Philippine Sea Operational Area

[Fall season]

Species

Stock name

1

Abundance

2

Density

(animals/km

2

)

3

ESA status

4

Blue whale

WNP

9,250

.00001

EN

Bryde's whale

WNP

20,501

0.0006

NL

Minke whale

WNP “O” Stock

25,049

0.0033

NL

Fin whale

WNP

9,250

5

NA

EN

Humpback whale

WNP

1,328

0.00089

EN

Omura's whale

WNP

1,800

0.00006

NL

Sperm whale

NP

102,112

0.00123

EN

Killer whale

WNP

12,256

0.00009

NL

Cuvier's beaked whale

WNP

90,725

0.0003

NL

Blainville`s beaked whale

WNP

8,032

0.0005

NL

Ginkgo-toothed beaked whale

NP

22,799

0.0005

NL

False killer whale

WNP—Pelagic

16,668

0.0029

NL

Pygmy killer whale

WNP

30,214

0.0021

NL

Melon-headed whale

WNP

36,770

0.00428

NL

Short-finned pilot whale

WNP

53,608

0.0076

NL

Risso's dolphin

WNP

83,289

0.0106

NL

Kogia

spp

WNP

350,553

0.0017

*

Fraser's dolphin

WNP

220,789

0.0069

NL

Common bottlenose dolphin

WNP

168,791

0.0146

NL

Deraniyagala's beaked whale

NP

22,799

0.0005

NL

Pantropical spotted dolphin

WNP

438,064

0.0137

NL

Striped dolphin

WNP

570,038

0.0164

NL

Spinner dolphin

WNP

1,015,059

0.00083

NL

Rough-toothed dolphin

WNP

145,729

0.0059

NL

Long-beaked common dolphin

WNP

279,182

0.1158

NL

Longman's beaked whale

WNP

4,571

0.00025

NL

1

NP = north Pacific; WNP = western north Pacific.

2

Refer to Table 3-2 of the Navy's application for literature references associated with abundance estimates presented in this table.

3

Refer to Table 3-2 of the Navy's application for literature references associated with density estimates presented in this table.

4

ESA Status: EN = Endangered; T = Threatened; NL = Not Listed.

5

NA in the Density column indicates that although the stock or DPS occurs in that mission area, it is not expected to occur during the season modeled.

Table 6—Abundance and Density Estimates for the Marine Mammal Species, Species Groups, and Stocks Associated With Mission Area 4, Offshore Guam

[Summer season]

Species

Stock name

1

Abundance

2

Density

(animals/km

2

)

3

ESA

status

4

Blue whale

WNP

9,250

NA

5

EN

Fin whale

WNP

9,250

NA

EN

Sei whale

NP

7,000

NA

EN

Bryde's whale

WNP

20,501

0.0004

NL

Minke whale

WNP “O” Stock

25,049

NA

NL

Humpback whale

WNP

1,328

NA

EN

Omura's whale

WNP

1,800

0.00004

NL

Sperm whale

NP

102,112

0.00123

EN

Pygmy sperm whale

WNP

350,553

0.00291

NL

Dwarf sperm whale

WNP

350,553

0.00714

NL

Cuvier's beaked whale

WNP

90,725

0.00079

NL

Blainville's beaked whale

WNP

8,032

0.001

NL

Ginkgo-toothed beaked whale

NP

22,799

0.00093

NL

Longman's beaked whale

WNP

4,571

0.0019

NL

Killer whale

WNP

12,256

0.00014

NL

False killer whale

WNP—Pelagic

16,668

0.00111

NL

Pygmy killer whale

WNP

30,214

0.00014

NL

Melon-headed whale

NMI

2,455

0.00428

NL

Short-finned pilot whale

WNP

53,608

0.0051

NL

Risso's dolphin

WNP

83,289

0.003

NL

Deraniyagala's beaked whale

NP

22,799

0.00093

NL

Fraser's dolphin

CNP

16,992

0.0069

NL

Common bottlenose dolphin

WNP

168,791

0.00245

NL

Pantropical spotted dolphin

WNP

438,064

0.0226

NL

Striped dolphin

WNP

570,038

0.00616

NL

Spinner dolphin

WNP

1,015,059

0.00083

NL

Rough-toothed dolphin

WNP

145,729

0.0026

NL

1

CNP = central north Pacific; NP = north Pacific; WNP = western north Pacific; NMI = Northern Mariana Islands.

2

Refer to Table 3-2 of the Navy's application for literature references associated with abundance estimates presented in this table.

3

Refer to Table 3-2 of the Navy's application for literature references associated with density estimates presented in this table.

4

ESA Status: EN = Endangered; T = Threatened; NL = Not Listed.

5

NA in the Density column indicates that although the stock or DPS occurs in that mission area, it is not expected to occur during the season modeled.

Table 7—Abundance and Density Estimates for the Marine Mammal Species, Species Groups, and Stocks Associated With Mission Area 5, Sea of Japan

[Fall season]

Species

Stock name

1

Abundance

2

Density

(animals/km

2

)

3

ESA

status

4

Fin whale

WNP

9,250

0.0009

EN

Bryde's whale

WNP

20,501

0.0001

NL

Minke whale

WNP “O” Stock

25,049

0.0004

NL

Minke whale

WNP “J” Stock

893

0.00016

NL

North Pacific right whale

WNP

922

5

NA

EN

Gray whale

WNP

140

0.00001

EN

6

Omura's whale

WNP

1,800

0.00001

NL

Sperm whale

NP

102,112

0.00123

EN

Stejneger's beaked whale

WNP

8,000

0.0005

NL

Baird's beaked whale

WNP

8,000

0.0003

NL

Cuvier's beaked whale

WNP

90,725

0.0031

NL

Harbor porpoise

WNP

31,046

0.0190

NL

False killer whale

IA-Pelagic

9,777

0.0027

NL

Killer whale

WNP

12,256

0.00009

NL

Short-finned pilot whale

WNP

53,608

0.0014

NL

Risso's dolphin

IA

83,289

0.0073

NL

Short-beaked common dolphin

WNP

3,286,163

0.0860

NL

Common bottlenose dolphin

IA

105,138

0.00077

NL

Kogia

spp

WNP

350,553

0.0017

*

Spinner dolphin

WNP

1,015,059

0.00083

NL

Pacific white-sided dolphin

NP

931,000

NA

NL

Dall's porpoise

SOJ

173,638

0.0520

NL

Long-beaked common dolphin

WNP

279,182

0.1158

NL

Rough-toothed dolphin

WNP

145,729

0.0026

NL

Striped dolphin

IA

570,038

0.00584

NL

Spotted seal

Southern stock

3,500

0.00001

T

1

IA = Inshore Archipelago; NP = north Pacific; SOJ = Sea of Japan; WNP = western north Pacific.

2

Refer to Table 3-2 of the Navy's application for literature references associated with abundance estimates presented in this table.

3

Refer to Table 3-2 of the Navy's application for literature references associated with density estimates presented in this table.

4

ESA Status: EN = Endangered; T = Threatened; NL = Not Listed.

5

NA in the Density column indicates that although the stock or DPS occurs in that mission area, it is not expected to occur during the season modeled.

6

Only the western Pacific population of gray whale is endangered under the ESA.

Table 8—Abundance and Density Estimates for the Marine Mammal Species, Species Groups, and Stocks Associated With Mission Area 6, East China Sea

[Summer season]

Species

Stock Name

1

Abundance

2

Density

(animals/km

2

)

3

ESA

status

4

Fin whale

ECS

500

0.0002

EN

Bryde's whale

ECS

137

0.0003

NL

Minke whale

WNP “O” Stock

25,049

0.0044

NL

Minke whale

WNP “J” Stock

893

0.0018

NL

North Pacific right whale

WNP

922

5

NA

EN

Gray whale

WNP

140

NA

EN

6

Omura's whale

WNP

1,800

0.00003

NL

Sperm whale

NP

102,112

0.00123

EN

Cuvier's beaked whale

WNP

90,725

0.0003

NL

Blainville's beaked whale

WNP

8,032

0.0005

NL

Ginkgo-toothed beaked whale

NP

22,799

0.0005

NL

False killer whale

IA-Pelagic

9,777

0.00111

NL

Pygmy killer whale

WNP

30,214

0.00014

NL

Melon-headed whale

WNP

36,770

0.00428

NL

Short-finned pilot whale

WNP

53,608

0.0016

NL

Risso's dolphin

IA

83,289

0.0106

NL

Short-beaked common dolphin

WNP

3,286,163

0.0461

NL

Fraser's dolphin

WNP

220,789

0.00694

NL

Common bottlenose dolphin

IA

105,138

0.00077

NL

Pantropical spotted dolphin

WNP

219,032

0.01374

NL

Striped dolphin

IA

570,038

0.00584

NL

Spinner dolphin

WNP

1,015,059

0.00083

NL

Pacific white-sided dolphin

NP

931,000

NA

NL

Rough-toothed dolphin

WNP

145,729

0.0026

NL

Killer whale

WNP

12,256

0.00009

NL

Kogia

spp

WNP

350,553

0.0017

*

Long-beaked common dolphin

WNP

279,182

0.1158

NL

Longman's beaked whale

WNP

4,571

0.00025

NL

Spotted seal

Southern stock

1,000

0.00001

T

1

ECS = East China Sea; IA = Inshore Archipelago; NP = north Pacific; WNP = western north Pacific.

2

Refer to Table 3-2 of the Navy's application for literature references associated with abundance estimates presented in this table.

3

Refer to Table 3-2 of the Navy's application for literature references associated with density estimates presented in this table.

4

ESA Status: EN = Endangered; T = Threatened; NL = Not Listed.

5

NA in the Density column indicates that although the stock or DPS occurs in that mission area, it is not expected to occur during the season modeled.

6

Only the western Pacific population of gray whale is endangered under the ESA.

Table 9—Abundance and Density Estimates for the Marine Mammal Species, Species Groups, and Stocks Associated With Mission Area 7, South China Sea

[Fall season]

Species

Stock name

1

Abundance

2

Density

(animals/km

2

)

3

ESA

status

4

Fin whale

WNP

9,250

0.0002

EN

Bryde's whale

WNP

20,501

0.0006

NL

Minke whale

WNP “O” Stock

25,049

0.0033

NL

Minke whale

WNP “J” Stock

893

0.0018

NL

Humpback whale

WNP

1,328

0.00036

EN

North Pacific right whale

WNP

922

5

NA

EN

Omura's whale

WNP

1,800

0. 00006

NL

Gray whale

WNP

140

0.00001

EN

6

Sperm whale

NP

102,112

0.0012

EN

Long-beaked common dolphin

WNP

279,182

0.1158

NL

Cuvier's beaked whale

WNP

90,725

0.0003

NL

Blainville's beaked whale

WNP

8,032

0.0005

NL

Ginkgo-toothed beaked whale

NP

22,799

0.0005

NL

False killer whale

IA-Pelagic

9,777

0.00111

NL

Pygmy killer whale

WNP

30,214

0.00014

NL

Melon-headed whale

WNP

36,770

0.00428

NL

Short-finned pilot whale

WNP

53,608

0.00159

NL

Risso's dolphin

IA

83,289

0.0106

NL

Longman's beaked whale

WNP

4,571

0.00025

NL

Fraser's dolphin

WNP

220,789

0.00694

NL

Common bottlenose dolphin

IA

105,138

0.00077

NL

Pantropical spotted dolphin

WNP

219,032

0.01374

NL

Striped dolphin

IA

570,038

0.00584

NL

Spinner dolphin

WNP

1,015,059

0.00083

NL

Rough-toothed dolphin

WNP

145,729

0.0026

NL

Deraniyagala's beaked whale

NP

22,799

0.0005

NL

Killer whale

WNP

12,256

0.00009

NL

Kogia

spp

WNP

350,553

0.0017

*

1

IA = Inshore Archipelago; NP = north Pacific; WNP = western north Pacific.

2

Refer to Table 3-2 of the Navy's application for literature references associated with abundance estimates presented in this table.

3

Refer to Table 3-2 of the Navy's application for literature references associated with density estimates presented in this table.

4

ESA Status: EN = Endangered; T = Threatened; NL = Not Listed.

5

NA in the Density column indicates that although the stock or DPS occurs in that mission area, it is not expected to occur during the season modeled.

6

Only the western Pacific population of gray whale is endangered under the ESA.

Table 10—Abundance and Density Estimates for the Marine Mammal Species, Species Groups, and Stocks Associated With Mission Area 8, Offshore Japan 25° to 40° N.

[Summer season]

Species

Stock name

1

Abundance

2

Density

(animals/km

2

)

3

ESA

status

4

Blue whale

WNP

9,250

5

NA

EN

Fin whale

WNP

9,250

0.0001

EN

Sei whale

NP

7,000

0.00029

EN

Bryde's whale

WNP

20,501

0.00041

NL

Minke whale

WNP “O” Stock

25,049

0.0003

NL

Humpback whale

WNP

1,328

0.00036

EN

Sperm whale

NP

102,112

0.0022

EN

Pygmy sperm whale

WNP

350,553

0.0018

NL

Dwarf sperm whale

WNP

350,553

0.0043

NL

Northern right whale dolphin

NP

68,000

NA

NL

Blainville's beaked whale

WNP

8,032

0.0007

NL

Hubb's beaked whale

NP

22,799

0.0005

NL

Killer whale

WNP

12,296

0.00009

NL

Longman's beaked whale

WNP

4,571

0.0003

NL

Baird's beaked whale

WNP

8,000

0.0001

NL

Cuvier's beaked whale

NP

90,725

0.00374

NL

Mesoplodon

spp

WNP

22,799

0.0005

NL

False killer whale

WNP-Pelagic

16,668

0.0036

NL

Pygmy killer whale

WNP

30,214

0.0001

NL

Melon-headed whale

WNP

36,770

0.0027

NL

Short-finned pilot whale

WNP

53,608

0.0021

NL

Risso's dolphin

WNP

83,289

0.0005

NL

Short-beaked common dolphin

WNP

3,286,163

0.0863

NL

Common bottlenose dolphin

WNP

168,791

0.00077

NL

Pantropical spotted dolphin

WNP

438,064

0.0113

NL

Striped dolphin

WNP

570,038

0.0058

NL

Spinner dolphin

WNP

1,015,059

0.0019

NL

Pacific white-sided dolphin

NP

931,000

0.0048

NL

Rough-toothed dolphin

WNP

145,729

0.0019

NL

Stejneger's beaked whale

WNP

8,000

0.0005

NL

Hawaiian monk seal

Hawaii

1,400

0.00001

EN

Northern fur seal

Western Pacific

503,609

NA

NL

1

NP = north Pacific; WNP = western north Pacific.

2

Refer to Table 3-2 of the Navy's application for literature references associated with abundance estimates presented in this table.

3

Refer to Table 3-2 of the Navy's application for literature references associated with density estimates presented in this table.

4

ESA Status: EN = Endangered; T = Threatened; NL = Not Listed.

5

NA in the Density column indicates that although the stock or DPS occurs in that mission area, it is not expected to occur during the season modeled.

Table 11—Abundance and Density Estimates for the Marine Mammal Species, Species Groups, and Stocks Associated With Mission Area 9, Offshore Japan 10° to 25° N.

[Winter season]

Species

Stock name

1

Abundance

2

Density

(animals/km

2

)

3

ESA

status

4

Blue whale

WNP

9,250

0.00001

EN

Bryde's whale

WNP

20,501

0.0003

NL

Fin whale

WNP

9,250

0.00001

EN

Humpback whale

WNP

1,328

0.00036

EN

Omura's whale

WNP

1,800

0.00003

NL

Sei whale

NP

7,000

0.0029

EN

Sperm whale

NP

102,112

0.00222

EN

Pygmy sperm whale

WNP

350,553

0.00176

NL

Dwarf sperm whale

WNP

350,553

0.0043

NL

Cuvier's beaked whale

WNP

90,725

0.00374

NL

False killer whale

WNP

16,668

0.00057

NL

Melon-headed whale

WNP

36,770

0.00267

NL

Short-finned pilot whale

WNP

53,608

0.00211

NL

Risso's dolphin

WNP

83,289

0.00046

NL

Pygmy killer whale

WNP

30,214

0.00006

NL

Common bottlenose dolphin

WNP

168,791

0.00077

NL

Pantropical spotted dolphin

WNP

438,064

0.01132

NL

Striped dolphin

WNP

570,038

0.00584

NL

Spinner dolphin

WNP

1,015,059

0.00187

NL

Rough-toothed dolphin

WNP

145,729

0.00185

NL

Blainville's beaked whale

WNP

8,032

0.0007

NL

Deraniyagala's beaked whale

NP

22,799

0.00093

NL

Fraser's dolphin

CNP

16,992

0.00251

NL

Ginkgo-toothed beaked whale

NP

22,799

0.00093

NL

Killer whale

WNP

12,256

0.00009

NL

Longman's beaked whale

WNP

4,571

0.00025

NL

1

NP = north Pacific; CNP = central north Pacific; WNP = western north Pacific.

2

Refer to Table 3-2 of the Navy's application for literature references associated with abundance estimates presented in this table.

3

Refer to Table 3-2 of the Navy's application for literature references associated with density estimates presented in this table.

4

ESA Status: EN = Endangered; T = Threatened; NL = Not Listed.

Table 12—Abundance and Density Estimates for the Marine Mammal Species, Species Groups, and Stocks Associated With Mission Area 10, Northern Hawaii

[Summer season]

Species

Stock name

1

Abundance

2

Density

(animals/km

2

)

3

ESA

status

4

Blue whale

CNP

81

5

NA

EN

Bryde's whale

Hawaii

798

0.0003

NL

Common minke whale

Hawaii

25,049

NA

NL

Humpback whale

Hawaii DPS

10,103

NA

NL

Fin whale

Hawaii

58

NA

EN

Sei whale

Hawaii

178

NA

EN

Sperm whale

Hawaii

3,354

0.0014

EN

Pygmy sperm

Hawaii

7,138

0.0029

NL

Dwarf sperm whale

Hawaii

17,519

0.00714

NL

Cuvier's beaked whale

Hawaii

1,941

0.0008

NL

Blainville's beaked whale

Hawaii

2,338

0.001

NL

Longman's beaked whale

Hawaii

4,571

0.0019

NL

Killer whale

Hawaii

101

0.00004

NL

False killer whale

Hawaii-Pelagic

1,540

0.0006

NL

False killer whale

Main Hawaiian Islands Insular

151

0.0012

EN

False killer whale

Northwestern Hawaiian Islands

617

0.0013

NL

Pygmy killer whale

Hawaii

3,433

0.0014

NL

Melon-headed whale

Hawaiian Islands

5,794

0.0012

NL

Melon-headed whale

Kohala Resident

447

0.03725

NL

Short-finned pilot whale

Hawaii

12,422

0.0051

NL

Risso's dolphin

Hawaii

7,256

0.003

NL

Fraser's dolphin

Hawaii

16,992

0.0069

NL

Common bottlenose dolphin

Hawaii pelagic

5,950

0.0025

NL

Common bottlenose dolphin

Kauai/Niihau

184

0.0001

NL

Common bottlenose dolphin

4 Islands

191

0.0001

NL

Common bottlenose dolphin

Oahu

743

0.0003

NL

Common bottlenose dolphin

Hawaii Island

128

0.0001

NL

Pantropical spotted dolphin

Hawaiian Pelagic

15,917

0.0067

NL

Pantropical spotted dolphin

Hawaiian Island

220

0.0067

NL

Pantropical spotted dolphin

Oahu

220

0.0067

NL

Pantropical spotted dolphin

4 Islands

220

0.0067

NL

Striped dolphin

Hawaii

20,650

0.0084

NL

Spinner dolphin

Hawaii Pelagic

3,351

0.0008

NL

Spinner dolphin

Kauai/Nihau

601

0.007

NL

Spinner dolphin

Hawaiian Island

631

0.007

NL

Spinner dolphin

Oahu/4 Islands

355

0.007

NL

Spinner dolphin

Kure/Midway Atoll

260

0.007

NL

Spinner dolphin

Pearl and Hermes Reef

300

0.007

NL

Rough-toothed dolphin

Hawaii

6,288

0.0026

NL

Hawaiian monk seal

Hawaii

1,112

0.00001

EN

1

CNP = central north Pacific; WNP = western north Pacific.

2

Refer to Table 3-2 of the Navy's application for literature references associated with abundance estimates presented in this table.

3

Refer to Table 3-2 of the Navy's application for literature references associated with density estimates presented in this table.

4

ESA Status: EN = Endangered; T = Threatened; NL = Not Listed.

5

NA in the Density column indicates that although the stock or DPS occurs in that mission area, it is not expected to occur during the season modeled.

Table 13—Abundance and Density Estimates for the Marine Mammal Species, Species Groups, and Stocks Associated With Mission Area 11, Southern Hawaii

[Fall season]

Species

Stock name

1

Abundance

2

Density

(animals/km

2

)

3

ESA

status

4

Blue whale

CNP

81

0.00003

EN

Fin whale

Hawaii

58

0.00002

EN

Bryde's whale

Hawaii

798

0.0003

NL

Common minke whale

Hawaii

25,049

0.0002

NL

Humpback whale

Hawaii DPS

10,103

0.00089

NL

Sei whale

Hawaii

178

0.0001

EN

Sperm whale

Hawaii

3,354

0.0014

EN

Pygmy sperm whale

Hawaii

7,138

0.0029

NL

Blainville's beaked whale

Hawaii

2,338

0.001

NL

Longman's beaked whale

Hawaii

4,571

0.0019

NL

Killer whale

Hawaii

101

0.00004

NL

False killer whale

Hawaii-Pelagic

1,540

0.0006

NL

False killer whale

Main Hawaiian Island Insular

151

0.0012

EN

Pygmy killer whale

Hawaii

3,433

0.0014

NL

Melon-headed whale

Hawaiian Islands

5,794

0.0012

NL

Melon-headed whale

Kohala Resident

447

0.03725

NL

Short-finned pilot whale

Hawaii

12,422

0.0051

NL

Risso's dolphin

Hawaii

7,256

0.003

NL

Fraser's dolphin

Hawaii

16,992

0.0069

NL

Common bottlenose dolphin

Hawaii Pelagic

5,950

0.00245

NL

Common bottlenose dolphin

Kauai/Niihau

184

0.0001

NL

Common bottlenose dolphin

4 Islands

191

0.0001

NL

Common bottlenose dolphin

Oahu

743

0.0003

NL

Common bottlenose dolphin

Hawaii Island

128

0.0001

NL

Pantropical spotted dolphin

Hawaiian Pelagic

15,917

0.0067

NL

Pantropical spotted dolphin

Hawaii Island

220

0.0067

NL

Pantropical spotted dolphin

Oahu

220

0.0067

NL

Pantropical spotted dolphin

4 Islands

220

0.0067

NL

Striped dolphin

Hawaii

20,650

0.0084

NL

Spinner dolphin

Hawaii Pelagic

3,351

0.0008

NL

Spinner dolphin

Kauai/Niihau

601

0.007

NL

Spinner dolphin

Hawaii Island

631

0.007

NL

Spinner dolphin

Oahu/4 Islands

355

0.007

NL

Rough toothed dolphin

Hawaii

6,288

0.0026

NL

Cuvier's beaked whale

Hawaii

1,914

0.0008

NL

Deraniyagala's beaked whale

NP

22,799

0.00093

NL

Dwarf sperm whale

Hawaii

17,519

0.00714

NL

Hawaiian monk seal

Hawaii

1,400

0.00001

EN

1

CNP = central north Pacific; WNP = western north Pacific.

2

Refer to Table 3-2 of the Navy's application for literature references associated with abundance estimates presented in this table.

3

Refer to Table 3-2 of the Navy's application for literature references associated with density estimates presented in this table.

4

ESA Status: EN = Endangered; T = Threatened; NL = Not Listed.

Table 14—Abundance and Density Estimates for the Marine Mammal Species, Species Groups, and Stocks Associated With Mission Area 12, Offshore Southern California

[Spring season]

Species

Stock name

1

Abundance

2

Density

(animals/km

2

)

3

ESA

status

4

Blue whale

ENP

1,647

0.00011

EN

Fin whale

CA/OR/WA

3,051

0.00022

EN

Sei whale

ENP

126

0.00009

EN

Bryde's whale

ENP

13,000

0.00001

NL

Common minke whale

CA/OR/WA

478

0.00026

NL

Humpback whale

Mexico DPS

1,918

0.00121

T

Gray whale

ENP

20,990

0.03090

NL

Gray whale

WNP

140

0.00001

EN

5

Sperm whale

CA/OR/WA

2,106

0.00337

EN

Pygmy sperm whale

CA/OR/WA

579

0.00108

NL

Stejneger's beaked whale

CA/OR/WA

694

0.00065

NL

Baird's beaked whale

CA/OR/WA

847

0.00046

NL

Cuvier's beaked whale

CA/OR/WA

6,590

0.00358

NL

Blainville's beaked whale

CA/OR/WA

694

0.00101

NL

Ginkgo-toothed beaked whale

CA/OR/WA

694

0.00020

NL

Hubbs beaked whale

CA/OR/WA

694

0.00086

NL

Striped dolphin

CA/OR/WA

10,908

0.02592

NL

Perrin's beaked whale

CA/OR/WA

694

0.00088

NL

Pygmy beaked whale

CA/OR/WA

694

0.00020

NL

Killer whale (offshore)

EP

240

0.00030

NL

Short-finned pilot whale

CA/OR/WA

760

0.00031

NL

Risso's dolphin

CA/OR/WA

6,272

0.0100

NL

Long-beaked common dolphin

CA

107,016

0.08591

NL

Short-beaked common dolphin

CA/OR/WA

411,211

0.95146

NL

Common bottlenose dolphin (offshore)

CA/OR/WA

1,006

0.01230

NL

Pacific white-sided dolphin

CA/OR/WA

26,930

0.21549

NL

Northern right whale dolphin

CA/OR/WA

21,332

0.13352

NL

Dall's porpoise

CA/OR/WA

42,000

0.02184

NL

Guadalupe fur seal

Mexico

7,408

0.00387

T

Northern fur seal

California

14,050

0.01775

NL

California sea lion

US (Pacific Temperate)

296,750

0.33596

NL

Harbor seal

California

30,968

0.02033

NL

Northern elephant seal

CA-Breeding

179,000

0.03222

NL

1

CA/OR/WA = California, Oregon, and Washington; ENP = eastern north Pacific; EP = eastern Pacific; WNP = western north Pacific; SMI = San Miguel Island.

2

Refer to Table 3-2 of the Navy's application for literature references associated with abundance estimates presented in this table.

3

Refer to Table 3-2 of the Navy's application for literature references associated with density estimates presented in this table.

4

ESA Status: EN = Endangered; T = Threatened; NL = Not Listed.

5

Only the western Pacific population of gray whale is endangered under the ESA.

Table 15—Abundance and Density Estimates for the Marine Mammal Species, Species Groups, and Stocks Associated With Mission Area 13, Western North Atlantic Off Florida

[Winter season]

Species

Stock name

1

Abundance

2

Density

(animals/km

2

)

3

ESA

status

4

Humpback whale

West Indies DPS

12,132

0.00004

NL

Common minke whale

Canadian East Coast

20,174

0.00230

NL

North Atlantic right whale

WNA

476

0.00002

EN

Sperm whale

WNA

2,288

0.00083

EN

Mesoplodon

spp.

WNA

7,092

0.00180

NL

Kogia

spp.

WNA

3,785

0.00094

NL

Cuvier's beaked whale

WNA

6,532

0.00166

NL

Common bottlenose dolphin

Offshore WNA

77,532

0.04195

NL

Common bottlenose dolphin

Southern Migratory Coast

9,173

0.00155

NL

Common bottlenose dolphin

Northern FL Coast

1,219

0.00155

NL

Common bottlenose dolphin

Central FL Coast

4,895

0.00155

NL

Short-finned pilot whale

WNA

21,515

0.00616

NL

Risso's dolphin

WNA

18,250

0.00411

NL

False killer whale

WNA

442

0.00008

NL

Killer whale

WNA

67

0.00001

NL

Short-beaked common dolphin

WNA

173,486

0.00125

NL

Pantropical spotted dolphin

WNA

3,333

0.00608

NL

Striped dolphin

WNA

54,807

0.00298

NL

Atlantic spotted dolphin

WNA

44,715

0.01143

NL

Spinner dolphin

WNA

262

0.00040

NL

Clymene dolphin (

Stenella clymene

)

WNA

6,086

0.02522

NL

Rough-toothed dolphin

WNA

271

0.00069

NL

1

WNA = western north Atlantic.

2

Refer to Table 3-2 of the Navy's application for literature references associated with abundance estimates presented in this table.

3

Refer to Table 3-2 of the Navy's application for literature references associated with density estimates presented in this table.

4

ESA Status: EN = Endangered; T = Threatened; NL = Not Listed.

Table 16—Abundance and Density Estimates for the Marine Mammal Species, Species Groups, and Stocks Associated With Mission Area 14, Northeastern Atlantic

[Summer season]

Species

Stock name

1

Abundance

2

Density

(animals/km

2

)

3

ESA

status

4

Blue whale

ENA

979

0.00002

EN

Fin whale

ENA

9,019

0.00100

EN

Sei whale

Iceland-Denmark Strait

10,300

0.00040

EN

Common minke whale

Northeast Atlantic

78,572

0.00329

NL

Humpback whale

Cape Verdes and West Africa DPS

11,572

0.00009

EN

Sperm whale

ENA

7,785

0.00077

EN

Cuvier's beaked whale

ENA

6,992

0.00700

NL

Gervais' beaked whale

ENA

6,992

0.00700

NL

Blainville's beaked whale

ENA

6,992

0.00700

NL

Sowerby's beaked whale

ENA

6,992

0.00700

NL

Northern bottlenose whale

ENA

19,538

0.00260

NL

Killer whale

Northern Norway

731

0.00001

NL

Kogia

spp.

ENA

3,785

0.00079

NL

Long-finned pilot whale

ENA

128,093

0.05400

NL

Risso's dolphin

ENA

18,250

0.00200

NL

Short-beaked common dolphin

ENA

172,930

0.01000

NL

Common bottlenose dolphin

ENA

35,780

0.00200

NL

Striped dolphin

ENA

67,414

0.00150

NL

True's beaked whale

ENA

6,992

0.00700

NL

Atlantic white-sided dolphin

ENA

3,904

0.00001

NL

White-beaked dolphin

ENA

16,536

0.01400

NL

Harbor porpoise

ENA

375,358

0.07400

NL

Harbor seal

NW Europe

40,414

0.04000

NL

Gray seal

NW Europe

116,800

0.00040

NL

1

ENA = eastern north Atlantic.

2

Refer to Table 3-2 of the Navy's application for literature references associated with abundance estimates presented in this table.

3

Refer to Table 3-2 of the Navy's application for literature references associated with density estimates presented in this table.

4

ESA Status: EN = Endangered; T = Threatened; NL = Not Listed.

Table 17—Abundance and Density Estimates for the Marine Mammal Species, Species Groups, and Stocks Associated With Mission Area 15, Mediterranean Sea

[Summer season]

Species

Stock name

1

Abundance

2

Density

(animals/km

2

)

3

ESA

status

4

Fin whale

MED

3,583

0.00168

EN

Cuvier's beaked whale

Alboran Sea

429

0.000108

NL

Long-finned pilot whale

ENA

21,515

0.0027

NL

Risso's dolphin

WMED

5,320

0.0011

NL

Short-beaked common dolphin

WMED

19,428

0.00144

NL

Common bottlenose dolphin

WMED

1,676

0.00058

NL

Sperm whale

WMED

396

0.00052

EN

Striped dolphin

WMED

117,880

0.0436

NL

1

ENA = eastern north Atlantic; MED = Mediterranean; WMED = western Mediterranean.

2

Refer to Table 3-2 of the Navy's application for literature references associated with abundance estimates presented in this table.

3

Refer to Table 3-2 of the Navy's application for literature references associated with density estimates presented in this table.

4

ESA Status: EN = Endangered; T = Threatened; NL = Not Listed.

Table 18—Abundance and Density Estimates for the Marine Mammal Species, Species Groups, and Stocks Associated With Mission Area 16, Arabian Sea

[Summer season]

Species

Stock name

1

Abundance

2

Density

(animals/km

2

)

3

ESA

status

4

Blue whale

NIND

3,432

0.00004

EN

Bryde's whale

NIND

9,176

0.0004

NL

Common minke whale

IND

257,500

0.00920

NL

Fin whale

IND

1,716

0.00092

EN

Humpback whale

XAR

200

0.00005

EN

Sperm whale

NIND

24,446

0.00877

EN

Dwarf sperm whale

IND

10,541

0.00006

NL

Cuvier's beaked whale

IND

27,272

0.00308

NL

Deraniyagala beaked whale

IND

16,867

0.00278

NL

Blainville's beaked whale

IND

16,867

0.00276

NL

Ginkgo-toothed beaked whale

IND

16,867

0.00278

NL

Longman's beaked whale

IND

16,867

0.01193

NL

False killer whale

IND

144,188

0.00025

NL

Pygmy killer whale

IND

22,029

0.00141

NL

Melon-headed whale

IND

64,600

0.00931

NL

Short-finned pilot whale

IND

268,751

0.03474

NL

Risso's dolphin

IND

452,125

0.08952

NL

Fraser's dolphin

IND

151,554

0.00194

NL

Common bottlenose dolphin

IND

785,585

0.05521

NL

Pantropical spotted dolphin

IND

736,575

0.00922

NL

Striped dolphin

IND

674,578

0.15196

NL

Spinner dolphin

IND

634,108

0.00718

NL

Rough-toothed dolphin

IND

156,690

0.00075

NL

Long-beaked common dolphin

IND

1,819,882

0.00013

NL

Pygmy sperm whale

IND

10,541

0.00002

NL

Killer whale

IND

12,593

0.00737

NL

Indo-Pacific bottlenose dolphin

IND

7,850

0.00055

NL

1

IND = Indian Ocean; NIND = northern Indian Ocean; XAR = Stock X Arabian Sea.

2

Refer to Table 3-2 of the Navy's application for literature references associated with abundance estimates presented in this table.

3

Refer to Table 3-2 of the Navy's application for literature references associated with density estimates presented in this table.

4

ESA Status: EN = Endangered; T = Threatened; NL = Not Listed.

Table 19—Abundance and Density Estimates for the Marine Mammal Species, Species Groups, and Stocks Associated With Mission Area 17, Andaman Sea

[Summer season]

Species

Stock name

1

Abundance

2

Density

(animals/km

2

)

3

ESA

status

4

Blue whale

NIND

3,432

0.00003

EN

Bryde's whale

NIND

9,176

0.00037

NL

Common minke whale

IND

257,500

0.00968

NL

Fin whale

IND

1,716

5

NA

EN

Omura's whale

IND

9,176

0.00037

NL

Sperm whale

NIND

24,446

0.00107

EN

Dwarf sperm whale

IND

10,541

0.00006

NL

Pygmy sperm whale

IND

10,541

0.00001

NL

Cuvier's beaked whale

IND

27,272

0.00480

NL

Blainville's beaked whale

IND

16,867

0.00094

NL

Ginkgo-toothed beaked whale

IND

16,867

0.00097

NL

Longman's beaked whale

IND

16,867

0.00459

NL

Killer whale

IND

12,593

0.00730

NL

False killer whale

IND

144,188

0.00024

NL

Fraser's dolphin

IND

151,554

0.0018

NL

Pygmy killer whale

IND

22,029

0.00125

NL

Melon-headed whale

IND

64,600

0.00878

NL

Short-finned pilot whale

IND

268,751

0.03543

NL

Risso's dolphin

IND

452,125

0.09173

NL

Long-beaked common dolphin

IND

1,819,882

0.00010

NL

Common bottlenose dolphin

IND

785,585

0.07261

NL

Indo-Pacific bottlenose dolphin

IND

7,850

0.00073

NL

Pantropical spotted dolphin

IND

736,575

0.00829

NL

Striped dolphin

IND

674,578

0.14123

NL

Spinner dolphin

IND

634,108

0.00701

NL

Rough-toothed dolphin

IND

156,690

0.00077

NL

Deraniyagala beaked whale

IND

16,867

0.00097

NL

1

IND = Indian Ocean; NIND = northern Indian Ocean.

2

Refer to Table 3-2 of the Navy's application for literature references associated with abundance estimates presented in this table.

3

Refer to Table 3-2 of the Navy's application for literature references associated with density estimates presented in this table.

4

ESA Status: EN = Endangered; T = Threatened; NL = Not Listed.

5

NA in the Density column indicates that although the stock or DPS occurs in that mission area, it is not expected to occur during the season modeled.

Table 20—Abundance and Density Estimates for the Marine Mammal Species, Species Groups, and Stocks Associated With Mission Area 18, Panama Canal

[Winter season]

Species

Stock name

1

Abundance

2

Density

(animals/km

2

)

3

ESA

status

4

Blue whale

ENP

1,647

0.00008

EN

Bryde's whale

ETP

13,000

0.0003

NL

Common minke whale

ETP

478

0.00031

NL

Fin whale

ENP

832

5

NA

EN

Humpback whale

Central America DPS

6,000

0.00001

EN

Sperm whale

ETP

22,700

0.0047

EN

Kogia

spp.

ETP

11,200

0.014

NL

Cuvier's beaked whale

ETP

20,000

0.00058

NL

Blainville's beaked whale

ETP

25,300

0.00225

NL

Ginkgo-toothed beaked whale

ETP

25,300

0.0016

NL

Longman's beaked whale

ETP

25,300

0.00225

NL

Pygmy beaked whale

ETP

25,300

0.00225

NL

Killer whale

ETP

8,500

0.00015

NL

False killer whale

ETP

39,800

0.0004

NL

Pygmy killer whale

ETP

38,900

0.0014

NL

Melon-headed whale

ETP

45,400

0.00313

NL

Short-finned pilot whale

ETP

160,200

0.01813

NL

Risso's dolphin

ETP

110,457

0.01781

NL

Short-beaked common dolphin

ETP

3,127,203

0.005

NL

Fraser's dolphin

ETP

289,300

0.001

NL

Common bottlenose dolphin

ETP

335,834

0.0375

NL

Pantropical spotted dolphin

NEOP

640,000

0.0375

NL

Striped dolphin

ETP

964,362

0.08125

NL

Spinner dolphin

Eastern

450,000

0.01875

NL

Rough-toothed dolphin

ETP

107,633

0.00488

NL

Mesoplodon

spp.

ETP

25,300

0.00225

NL

Deraniyagala beaked whale

ETP

25,300

0.00225

NL

1

ETP = eastern tropical Pacific; ENP = eastern northern Pacific; NEOP = northeastern offshore Pacific.

2

Refer to Table 3-2 of the Navy's application for literature references associated with abundance estimates presented in this table.

3

Refer to Table 3-2 of the Navy's application for literature references associated with density estimates presented in this table.

4

ESA Status: EN = Endangered; T = Threatened; NL = Not Listed.

5

NA in the Density column indicates that although the stock or DPS occurs in that mission area, it is not expected to occur during the season modeled.

Table 21—Abundance and Density Estimates for the Marine Mammal Species, Species Groups, and Stocks Associated With Mission Area 19, Northeastern Australia

[Spring season]

Species

Stock name

1

Abundance

2

Density

(animals/km

2

)

3

ESA

status

4

Blue whale

WSP

9,250

0.00001

EN

Fin whale

WSP

9,250

0.0002

EN

Bryde's whale

WSP

20,501

0.0006

NL

Common minke whale

WSP

25,049

0.0044

EN

Humpback whale

East Australia DPS

14,500

0.00089

NL

Omura's whale

WSP

1,800

0.00006

NL

Sei whale

WSP

7,000

0.0006

EN

Sperm whale

WSP

102,112

0.00123

EN

Cuvier's beaked whale

WSP

90,725

0.0054

NL

Blainville's beaked whale

WSP

8,032

0.0005

NL

Ginkgo-toothed beaked whale

WSP

22,799

0.0005

NL

Longman's beaked whale

WSP

4,571

0.00025

NL

Kogia

spp.

WSP

350,553

0.0031

NL

Killer whale

WSP

12,256

0.00009

NL

False killer whale

WSP

16,668

0.0029

NL

Pygmy killer whale

WSP

30,214

0.0021

NL

Melon-headed whale

WSP

36,770

0.00428

NL

Risso's dolphin

WSP

83,289

0.0106

NL

Short-beaked common dolphin

WSP

3,286,163

0.0562

NL

Fraser's dolphin

WSP

220,789

0.0069

NL

Common bottlenose dolphin

WSP

168,791

0.0146

NL

Pantropical spotted dolphin

WSP

438,064

0.0137

NL

Striped dolphin

WSP

570,038

0.0329

NL

Spinner dolphin

WSP

1,015,059

0.00083

NL

Pilot whales

WSP

53,608

0.0153

NL

Rough-toothed dolphin

WSP

145,729

0.0059

NL

1

GVEA = group V east Australia; WSP = western south Pacific.

2

Refer to Table 3-2 of the Navy's application for literature references associated with abundance estimates presented in this table.

3

Refer to Table 3-2 of the Navy's application for literature references associated with density estimates presented in this table.

4

ESA Status: EN = Endangered; T = Threatened; NL = Not Listed.

Table 22—Abundance and Density Estimates for the Marine Mammal Species, Species Groups, and Stocks Associated With Mission Area 20, Northwestern Australia

[Winter season]

Species

Stock name

1

Abundance

2

Density

(animals/km

2

)

3

ESA

status

4

Blue whale

SIND

1,657

5

NA

EN

Fin whale

SIND

38,185

0.00001

EN

Bryde's whale

SIND

13,854

0.00032

NL

Antarctic minke whale

ANT

90,000

NA

NL

Common minke whale

IND

257,500

NA

NL

Humpback whale

Western Australia DPS

13,640

NA

NL

Omura's whale

IND

13,854

0.00032

NL

Sei whale

IND

13,854

0.00001

EN

Blainville's beaked whale

IND

16,867

0.00083

NL

Common bottlenose dolphin

IND

3,000

0.03630

NL

Cuvier's beaked whale

IND

76,500

0.00399

NL

Dwarf sperm whale

IND

10,541

0.00004

NL

False killer whale

IND

144,188

0.00020

NL

Fraser's dolphin

IND

151,554

0.00145

NL

Killer whale

IND

12,593

0.00585

NL

Longman's beaked whale

IND

16,867

0.00393

NL

Melon-headed whale

IND

64,600

0.00717

NL

Pantropical spotted dolphin

IND

736,575

0.00727

NL

Pygmy killer whale

IND

22,029

0.00100

NL

Risso's dolphin

IND

452,125

0.07152

NL

Rough-toothed dolphin

IND

156,690

0.00059

NL

Short-finned pilot whale

IND

268,751

0.02698

NL

Southern bottlenose whale

IND

599,300

0.00083

NL

Spade-toothed beaked whale

IND

16,867

0.00083

NL

Sperm whale

SIND

24,446

0.00096

EN

Spinner dolphin

IND

634,108

0.00561

NL

Striped dolphin

IND

674,578

0.12018

NL

1

ANT = Antarctic; SIND = southern Indian Ocean; IND = Indian Ocean.

2

Refer to Table 3-2 of the Navy's application for literature references associated with abundance estimates presented in this table.

3

Refer to Table 3-2 of the Navy's application for literature references associated with density estimates presented in this table.

4

ESA Status: EN = Endangered; T = Threatened; NL = Not Listed.

5

NA in the Density column indicates that although the stock or DPS occurs in that mission area, it is not expected to occur during the season modeled.

Table 23—Abundance and Density Estimates for the Marine Mammal Species, Species Groups, and Stocks Associated With Mission Area 21, Northeast of Japan

[Summer season]

Species

Stock name

1

Abundance

2

Density

(animals/km

2

)

3

ESA

status

4

Blue whale

WNP

9,250

5

NA

EN

Common minke whale

WNP “O”

25,049

0.0022

NL

Fin whale

WNP

9,250

0.0002

EN

Humpback whale

WNP

1,328

0.00050

EN

North Pacific right whale

WNP

922

0.00001

EN

Sei whale

NP

7,000

0.00029

EN

Western North Pacific gray whale

Western DPS

140

0.00001

EN

Baird's beaked whale

WNP

8,000

0.0029

NL

Cuvier's beaked whale

WNP

90,725

0.0054

NL

Dall's porpoise

WNP

173,638

0.0650

NL

Killer whale

WNP

12,256

0.0036

NL

Pacific white-sided dolphin

NP

931,000

0.0048

NL

Short-beaked common dolphin

WNP

3,286,163

0.0863

NL

Sperm whale

NP

102,112

0.0022

EN

Stejneger's beaked whale

WNP

8,000

0.0005

NL

Northern fur seal

Western Pacific

503,609

0.01378

NL

Ribbon seal

NP

61,100

0.0452

NL

Spotted seal

Bering Sea DPS

460,268

0.2770

NL

Steller sea lion

West-Asian stock and Western DPS

62,218

0.00001

EN

1

IND = Indian Ocean; NP = northern Pacific; WNP = western north Pacific; ENP = eastern north Pacific.

2

Refer to Table 3-2 of the Navy's application for literature references associated with abundance estimates presented in this table.

3

Refer to Table 3-2 of the Navy's application for literature references associated with density estimates presented in this table.

4

ESA Status: EN = Endangered; T = Threatened; NL = Not Listed.

5

NA in the Density column indicates that although the stock or DPS occurs in that mission area, it is not expected to occur during the season modeled.

Table 24—Abundance and Density Estimates for the Marine Mammal Species, Species Groups, and Stocks Associated With Mission Area 22, Southern Gulf of Alaska

[Summer season]

Species

Stock name

1

Abundance

2

Density

(animals/km

2

)

3

ESA

status

4

Blue whale

ENP

1,647

0.00051

EN

Common minke whale

AK

1,233

0.0006

NL

Eastern North Pacific gray whale

ENP

20,990

0.00019

NL

Fin whale

AK/NE Pacific

1,368

0.00049

EN

Humpback whale

Hawaii DPS

Mexico DPS

WNP DPS

10,103

0.00050

NL

T

EN

North Pacific right whale

ENP

31

0.00003

EN

Sei whale

ENP

126

0.00007

EN

Baird's beaked whale

AK

847

0.0004

NL

Cuvier's beaked whale

AK

6,590

0.00245

NL

Dall's porpoise

AK

173,638

0.07214

NL

Killer whale

ENP AK resident

2,347

0.005

NL

Killer whale

ENP Gulf of AK, Aleutian Islands, and Bering Sea Transient

587

0.00021

NL

Pacific white-sided dolphin

NP

26,880

0.0208

NL

Sperm whale

NP

102,112

0.00127

EN

Stejneger's beaked whale

AK

694

0.00084

NL

Northern elephant seal

California Breeding

179,000

0.0038

NL

Northern fur seal

EP

648,534

0.03211

NL

Ribbon seal

AK

184,000

0.00001

NL

Steller sea lion

Eastern DPS

60,131

0.01085

NL

Steller sea lion

Western DPS

49,497

0.01085

EN

1

IND = Indian Ocean; NP = northern Pacific; ENP = eastern north Pacific; AK = Alaska.

2

Refer to Table 3-2 of the Navy's application for literature references associated with abundance estimates presented in this table.

3

Refer to Table 3-2 of the Navy's application for literature references associated with density estimates presented in this table.

4

ESA Status: EN = Endangered; T = Threatened; NL = Not Listed.

Table 25—Abundance and Density Estimates for the Marine Mammal Species, Species Groups, and Stocks Associated With Mission Area 23, Southern Norwegian Basin

[Summer season]

Species

Stock name

1

Abundance

2

Density

(animals/km

2

)

3

ESA

status

4

Blue whale

ENA

979

0.00001

EN

Common minke whale

Northeast Atlantic

78,572

0.03206

NL

Fin whale

North-West Norway

6,409

0.00157

EN

Humpback whale

Cape Verdes-NW Africa DPS

West Indies DPS

11,572

0.00009

EN

NL

Sei whale

Iceland-Denmark Strait

10,300

0.00001

EN

Atlantic white-sided dolphin

ENA

3,904

0.00001

NL

Cuvier's beaked whale

ENA

6,992

0.011

NL

Harbor porpoise

ENA

375,358

0.074

NL

Killer whale

Northern Norway

731

0.00001

NL

Long-finned pilot whale

ENA

128,093

0.054

NL

Northern bottlenose dolphin

ENA

19,538

0.0026

NL

Sowerby's beaked whale

ENA

6,992

0.011

NL

Sperm whale

ENA

7,785

0.0049

EN

White-beaked dolphin

ENA

16,536

0.011

NL

Hooded seal

West Ice

84,020

0.00811

NL

1

ENA = eastern north Atlantic.

2

Refer to Table 3-2 of the Navy's application for literature references associated with abundance estimates presented in this table.

3

Refer to Table 3-2 of the Navy's application for literature references associated with density estimates presented in this table.

4

ESA Status: EN = Endangered; T = Threatened; NL = Not Listed.

Table 26—Abundance and Density Estimates for the Marine Mammal Species, Species Groups, and Stocks Associated With Mission Area 24, Western North Atlantic off Virginia/Maryland

[Summer season]

Species

Stock name

1

Abundance

2

Density

(animals/km

2

)

3

ESA

status

4

Common minke whale

Canadian East Coast

20,741

0.00013

NL

Fin whale

WNA

1,618

0.00075

EN

Humpback whale

West Indies DPS

12,312

0.00006

NL

North Atlantic right whale

WNA

476

<0.00001

NL

Atlantic spotted dolphin

WNA

44,715

0.09630

NL

Clymene dolphin

WNA

6,086

0.01424

NL

Common bottlenose dolphin

Offshore WNA

77,532

0.04241

NL

Northern Migratory Coastal

11,548

0.00236

NL

Southern Migratory Coastal

9,173

0.00236

NL

Cuvier's beaked whale

WNA

6,532

0.00878

NL

False killer whale

WNA

442

0.00008

NL

Killer whale

WNA

67

0.00001

NL

Kogia

spp

WNA

3,785

0.00079

NL

Mesoplodon

spp

WNA

7,092

0.00954

NL

Pantropical spotted dolphin

WNA

3,333

0.00515

NL

Risso's dolphin

WNA

18,250

0.02202

NL

Rough-toothed dolphin

WNA

271

0.00060

NL

Short-beaked common dolphin

WNA

173,486

0.07284

NL

Short-finned pilot whale

WNA

21,515

0.02215

NL

Sperm whale

WNA

2,288

0.01274

EN

Spinner dolphin

WNA

262

0.00034

NL

Striped dolphin

WNA

54,807

0.13345

NL

1

WNA = western north Atlantic.

2

Refer to Table 3-2 of the Navy's application for literature references associated with abundance estimates presented in this table.

3

Refer to Table 3-2 of the Navy's application for literature references associated with density estimates presented in this table.

4

ESA Status: EN = Endangered; T = Threatened; NL = Not Listed.

Table 27—Abundance and Density Estimates for the Marine Mammal Species, Species Groups, and Stocks Associated With Mission Area 25, Labrador Sea

[Winter season]

Species

Stock name

1

Abundance

2

Density

(animals/km

2

)

3

ESA

status

4

Blue whale

WNA

440

0.00002

EN

Common minke whale

Canadian East Coast

20,741

0.00013

NL

Fin whale

Canadian East Coast

1,352

0.00005

EN

Humpback whale

West Indies DPS

12,312

0.00019

NL

North Atlantic right whale

WNA

476

<0.00001

EN

Sei whale

Labrador Sea

965

0.00002

EN

Atlantic white-sided dolphin

Labrador Sea

24,422

0.00200

NL

Harbor porpoise

Newfoundland

3,326

0.00160

NL

Killer whale

WNA

67

0.00001

NL

Long-finned pilot whale

Canadian East Coast

6,134

0.00370

NL

Northern bottlenose dolphin

Davis Strait

50

0.00001

NL

Short-beaked common dolphin

WNA

173,486

0.00100

NL

Sowerby's beaked whale

WNA

50

0.00001

NL

Sperm whale

WNA

2,288

0.00127

EN

White-beaked dolphin

Canadian East Coast

15,625

0.00077

NL

Arctic ringed seal

Arctic

787,000

0.07300

NL

Harp seal

WNA

7,411,000

0.07043

NL

Hooded seal

WNA

592,100

0.0081

NL

1

WNA = western north Atlantic.

2

Refer to Table 3-2 of the Navy's application for literature references associated with abundance estimates presented in this table.

3

Refer to Table 3-2 of the Navy's application for literature references associated with density estimates presented in this table.

4

ESA Status: EN = Endangered; T = Threatened; NL = Not Listed.

Table 28—Abundance and Density Estimates for the Marine Mammal Species, Species Groups, and Stocks Associated With Mission Area 26, Sea of Okhotsk

[Spring season]

Species

Stock name

1

Abundance

2

Density

(animals/km

2

)

3

ESA

status

4

Bowhead whale

Okhotsk Sea

247

0.00001

EN

Common minke whale

WNP “O”

WNP “J”

25,049

893

0.01727

0.00062

NL

EN

Fin whale

WNP

9,250

0.0002

EN

Humpback whale

WNP DPS

1,328

0.00089

EN

North Pacific right whale

WNP

922

5

NA

EN

Western North Pacific gray whale

Western DPS

140

NA

EN

Baird's beaked whale

WNP

8,000

0.0015

NL

Beluga whale

Okhotsk Sea

12,226

0.0071

NL

Cuvier's beaked whale

WNP

90,725

0.0054

Nl

Dall's porpoise

WNP dalli-trype

111,402

0.18031

NL

WNP truei-type

101,173

0.16375

NL

Harbor porpoise

WNP

31,046

0.0190

NL

Killer whale

Okhotsk-Kamchatka-Western Aleutians Transient

12,256

0.0036

NL

Pacific white-sided dolphin

NP

931,000

0.0048

NL

Sperm whale

NP

102,112

0.0022

EN

Northern fur seal

Western Pacific

503,609

0.08031

NL

Okhotsk ringed seal

Okhotsk

676,000

0.23881

T

Pacific bearded seal

Okhotsk DPS

200,000

0.01174

T

Ribbon seal

Sea of Okhotsk

124,000

0.0904

NL

Spotted seal

Sea of Okhotsk DPS

180,000

0.2770

NL

Steller sea lion

Western DPS

82,516

0.02189

EN

1

WNP = western north Pacific.

2

Refer to Table 3-2 of the Navy's application for literature references associated with abundance estimates presented in this table.

3

Refer to Table 3-2 of the Navy's application for literature references associated with density estimates presented in this table.

4

ESA Status: EN = Endangered; T = Threatened; NL = Not Listed.

5

NA in the Density column indicates that although the stock or DPS occurs in that mission area, it is not expected to occur during the season modeled.

Information on how the density and stock/abundance estimates were derived for the selected mission sites is in the Navy's application. These data are derived from the best available, published source documentation, and provide general area information for each mission area with species-specific information on the animals that could occur in that area, including estimates for their stock abundance and density. The Navy developed the abundance and density estimates by first using estimates from line-transect surveys that occurred in or near each of the 26 model sites (

e.g.,

Barlow, 2006). However, density estimates require more sophisticated sampling and analysis and were not always available for each species at all sites. When density estimates were not available from a survey in the operating area, the Navy extrapolated density estimates from a region with similar oceanographic characteristics to that operating area. For example, the eastern tropical Pacific has been extensively surveyed and provides a comprehensive understanding of marine mammals in temperate oceanic waters (Ferguson and Barlow, 2001, 2003). Density estimates for some mission areas/model sites were also derived from the Navy's Marine Species Density Database (DoN, 2016b). In addition, density estimates are usually not available for rare marine mammal species or for those that have been newly defined (

e.g.,

the Deraniyagala's beaked whale). For these species, the lowest density estimate of 0.0001 animals/square kilometer (0.0001 animals/km

2

) was used in the take analysis to reflect the low probability of occurrence in a specific SURTASS LFA sonar mission area. Further, the Navy pooled density estimates for species of the same genus if sufficient data are not available to compute a density for individual species or the species are difficult to distinguish at sea, which is often the case for pilot whales and beaked whales, as well as the pygmy and dwarf sperm whales. Density estimates are available for these species

groups rather than the individual species.

The Navy provides detailed descriptions of the distribution, abundance, diving behavior, life history, and hearing vocalization information for each affected marine mammal species with confirmed or possible occurrence within SURTASS LFA sonar operational areas in section 4 (pages 4-1 through 4-71) of the application, which is available online at

http://www.nmfs.noaa.gov/pr/permits/incidental.htm#applications

).

Although not repeated in this document, NMFS has reviewed these data, determined them to be the best available scientific information for the proposed rulemaking, and considers this information part of the administrative record for this action. Additional information is available in NMFS' Marine Mammal Stock Assessment Reports, which may be viewed at

http://www.nmfs.noaa.gov/pr/sars/species.htm.

NMFS refers the public to Table 3-2 (pages 3-9 through 3-36) of the Navy's application for literature references associated with abundance and density estimates presented in these tables.

Brief Background on Sound, Marine Mammal Hearing, and Vocalization

Underwater Sound

An understanding of the basic properties of underwater sound is necessary to comprehend many of the concepts and analyses presented in this document. Sound is a wave of pressure variations propagating through a medium (for the sonar considered in this proposed rulemaking, the medium is seawater). Pressure variations are created by compressing and relaxing the medium. Sound measurements can be expressed in two forms: Intensity and pressure. Acoustic intensity is the average rate of energy transmitted through a unit area in a specified direction and is expressed in watts per square meter (W/m

2

). Acoustic intensity is rarely measured directly, it is derived from ratios of pressures; the standard reference pressure for underwater sound is 1 μPa (Richardson

et al.,

1995).

Acousticians have adopted a logarithmic scale for sound intensities, which is denoted in dB. The logarithmic nature of the scale means that each 10 dB increase is a ten-fold increase in power (

e.g.,

20 dB is a 100-fold increase, 30 dB is a 1,000-fold increase). Humans perceive a 10-dB increase in noise as a doubling of sound level, or a 10-dB decrease in noise as a halving of sound level. Sound pressure level or SPL implies a decibel measure and a reference pressure that is used as the denominator of the ratio.

Sound frequency is measured in cycles per second, referred to as Hertz (Hz), and is analogous to musical pitch; high-pitched sounds contain high frequencies and low-pitched sounds contain low frequencies. Natural sounds in the ocean span a large range of frequencies: From earthquake noise at five Hz to harbor porpoise clicks at 150,000 Hz (150 kilohertz (kHz)). These sounds are so low or so high in pitch that humans cannot even hear them; acousticians call these infrasonic (typically below 20 Hz, which is considered the low frequency bound of human hearing) and ultrasonic (typically above 20,000 Hz, which is considered the upper bound of human hearing) sounds, respectively. A single sound may be made up of multiple frequencies. Sounds made up of only a small range of frequencies are called narrowband, and sounds with a broad range of frequencies are called broadband. Explosives are an example of a broadband sound source and tactical military sonars are an example of a narrowband sound source.

Metrics Used in This Document

This section includes a brief explanation of the sound measurements frequently used in the discussions of acoustic effects in this document.

Sound Pressure Level

Sound pressure level (SPL) is expressed as the ratio of a measured sound pressure and a reference level. The commonly used reference pressure level in underwater acoustics is 1 μPa, and the units for SPLs are decibels (dB) re: 1 μPa. SPL (in dB) = 20 log (pressure/reference pressure). SPL is an instantaneous measurement and can be expressed as the peak, the peak-peak (p-p), or the root mean square (rms). SPL does not directly take the duration of exposure to a sound into account, though it should be noted that the duration over which the root mean square pressure is averaged since it influences the result. Root mean square pressure, which is the square root of the arithmetic average of the squared instantaneous pressure values (Urick, 1983), is typically used in discussions of behavioral effects of sounds on vertebrates in part because behavioral effects, which often result from auditory cues, may be better expressed through averaged units than by peak pressures. All references to SPL in this document refer to the root mean square unless otherwise noted.

Cumulative Sound Exposure Level

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

2

-s) represents the total energy contained within a pulse, and considers both exposure level and duration of exposure. The NMFS 2016 Acoustic Technical Guidance builds upon the foundation provided by Southall

et al.

(2007), while incorporating new information available since development of that work (

e.g.,

Finneran, 2015). Southall

et al.

(2007) recommended specific thresholds under the dual metric approach (

i.e.,

peak SPL (SPL

pk

) and cumulative SEL (SEL

cum

)), and that marine mammals be divided into hearing groups based on measured or estimated hearing ranges. The premise of the dual criteria approach is that, while there is no definitive answer to the question of which acoustic metric is most appropriate for assessing the potential for auditory injury, both the exposure level and duration of received signals are important to an understanding of the potential for injury. Therefore, peak SPL is used to define a pressure criterion above which auditory injury is predicted to occur, regardless of exposure duration (

i.e.,

any single exposure at or above this level is considered to cause auditory injury), and the SEL

cum

metric is used to account for the total energy received over the specified duration of sound exposure (

i.e.,

metric accounts for both received level and duration of exposure) (Southall

et al.,

2007; NMFS, 2016). As SPL

pk

is applicable to impulsive noise, it is not applicable to SURTASS LFA sonar and is not discussed further here. Note that SEL

cum

acoustic thresholds also incorporate marine mammal auditory weighting functions. NMFS (2016) recommends 24 hours as a maximum accumulation period relative to SEL

cum

thresholds. For further discussion of auditory weighting functions and their application or metrics associated with evaluating noise-induced hearing loss, please see NMFS (2016). Table 29 displays auditory impact thresholds provided by NMFS (2016).

Table 29—TTS and PTS Onset Thresholds for Non-Impulsive Sounds

1

Hearing group

Cumulative

sound exposure

level for TTS

1

(dB)

Cumulative

sound exposure

level for PTS

1

(dB)

Low-frequency cetaceans

179

199

Mid-frequency cetaceans

178

198

High-frequency cetaceans

153

173

Phoicid pinnipeds (PW) (Underwater)

181

201

Otariid pinnipeds (OW) (Underwater)

199

219

1

Referenced to 1 μPa

2

s; weighted according to appropriate auditory weighting function.

Single Ping Equivalent (SPE)

To model potential behavioral impacts to marine animals from exposure to SURTASS LFA sonar sound, the Navy has developed a methodology to estimate the total exposure of modeled animals exposed to multiple pings over an extended period of time. The Navy's acoustic model analyzes the following components: (1) The LFA sonar source modeled as a point source, with an effective source level (SL) in dB re: 1 μPa at 1 m (SPL); (2) a 60-sec duration signal; and (3) a beam pattern that is correct for the number and spacing of the individual projectors (source elements). This source model, when combined with the three-dimensional transmission loss (TL) field generated by the Parabolic Equation (PE) acoustic propagation model, defines the received level (RL) (in SPL) sound field surrounding the source for a 60-sec LFA sonar signal (

i.e.,

the SPE metric accounts for received level and exposure from multiple pings). To estimate the total exposure of animals exposed to multiple pings, the Navy models the RLs for each modeled location and any computer-simulated marine mammals (animats) within the location, records the exposure history of each animat, and generates a SPE value. Thus, the Navy can model the SURTASS LFA sound field, providing a four-dimensional (position and time) representation of a sound pressure field within the marine environment and estimates of an animal's exposure to sound over a period of 24 hours.

Figure 2 shows the Navy calculation that converts SPL values to SPE values in order to estimate impacts to marine mammals from SURTASS LFA sonar transmissions. For a more detailed explanation of the SPE calculations, NMFS refers the public to Appendix B of the Navy's 2016 DSEIS/SOEIS.

EP27AP17.001

Marine Mammal Hearing

Cetaceans have an auditory anatomy that follows the basic mammalian pattern, with some changes to adapt to the demands of hearing in the sea. The typical mammalian ear is divided into an outer ear, middle ear, and inner ear. The outer ear is separated from the inner ear by a tympanic membrane, or eardrum. In terrestrial mammals, the outer ear, eardrum, and middle ear transmit airborne sound to the inner ear, where the sound waves are propagated through the cochlear fluid. Since the impedance of water (

i.e.,

the product of density and sound speed) is close to that of the tissues of a cetacean, the outer ear is not required to transduce sound energy as it does when sound waves travel from air to fluid (inner ear). Sound waves traveling through the inner ear cause the basilar membrane to vibrate. Specialized cells, called hair cells, respond to the vibration and produce nerve pulses that are transmitted to the central nervous system. Acoustic energy causes the basilar membrane in the cochlea to vibrate. Sensory cells at different positions along the basilar membrane are excited by different frequencies of sound (Pickles, 1998).

When considering the influence of various kinds of sound on the marine environment, it is necessary to understand that different kinds of marine life are sensitive to different frequencies of sound. Based on available behavioral data, audiograms derived using auditory evoked potential (AEP) techniques, anatomical modeling, and other data, Southall

et al.

(2007) designated “functional hearing groups” for marine mammals and estimated the lower and upper frequencies of functional hearing (

i.e.,

the frequencies that the species can actually hear) of these groups as follows:

• Low frequency (LF) cetaceans (13 species of mysticetes): Southall

et al.

(2007) estimates that functional hearing occurs between approximately seven Hz and 22 kHz;

• Mid-frequency (MF) cetaceans (32 species of dolphins, six species of larger toothed whales, and 19 species of beaked and bottlenose whales): Southall

et al.

(2007) estimates that functional hearing occurs between approximately 150 Hz and 160 kHz;

• High frequency (HF) cetaceans (eight species of true porpoises, six species of river dolphins,

Kogia,

the franciscana, and four species of cephalorhynchid

s

): Southall

et al.

(2007) estimates that functional hearing

occurs between approximately 200 Hz and 180 kHz.

• Pinnipeds in Water: Southall

et al.

(2007) estimates that functional hearing occurs between approximately 75 Hz and 75 kHz, with the greatest sensitivity between approximately 700 Hz and 20 kHz.

In August 2016 NMFS released its Technical Guidance for Assessing the Effects of Anthropogenic Sound on Marine Mammal Hearing (NMFS 2016 Acoustic Technical Guidance), which modified the hearing groups proposed in Southall

et al.

(2007) in the following ways:

• Division of pinnipeds into phocids in water (PW) and otariids in water (OW) hearing groups; and

• Re-Categorization of two species of dolphins (hourglass [

Lagenorhynchus cruiger

] and Peale's [

L. australis

]) from mid-frequency (MF) to high-frequency (HF) hearing group.

Therefore, under the new NMFS 2016 Acoustic Technical Guidance, there are five marine mammal hearing group categories, with associated generalized hearing ranges as shown in Table 30 (note that animals are less sensitive to sounds at the outer edge of their generalized hearing range and most sensitive to sounds of frequencies within a smaller range somewhere in the middle of their functional hearing range).

Table 30—Marine Mammal Hearing Groups

[NMFS, 2016]

Hearing group

Generalized hearing range

1

Low-frequency (LF) cetaceans (baleen whales)

7 Hz to 35 kHz.

Mid-frequency (MF) cetaceans (dolphins, toothed whales, beaked whales, bottlenose whales)

150 Hz to 160 kHz.

High-frequency (HF) cetaceans (true porpoises,

Kogia,

river dolphins, cephalorhynchid,

Lagenorhynchus

cruciger &

L. australis

)

275 Hz to 160 kHz.

Phocid pinnipeds underwater (PW) (true seals)

50 Hz to 86 kHz.

Otariid pinnipeds underwater (OW) (sea lions and fur seals)

60 Hz to 39 kHz.

1

Represents the generalized hearing range for the entire group as a composite (

i.e.,

all species within the group), where individual species' hearing ranges are typically not as broad. Generalized hearing range chosen based on ~65 dB threshold from normalized composite audiogram, with the exception for lower limits for LF cetaceans (Southall

et al.

2007) and PW pinniped (approximation).

Marine Mammal Hearing Groups and LFA Sonar

Baleen (mysticete) whales (members of the LF hearing group) have inner ears that appear to be specialized for low-frequency hearing. Conversely, most odontocetes (

i.e.,

dolphins and porpoises) have inner ears that are specialized to hear mid and high frequencies. Pinnipeds, which lack the highly specialized active biosonar systems of odontocetes, have inner ears that are specialized to hear a broad range of frequencies in water (Southall

et al.,

2007). Based on an extensive suite of reported laboratory measurements (DoN, 2001, Ketten, 1997, Southall

et al.,

2007), the LFA sound source is below the range of best hearing sensitivity for MF and HF odontocete and pinnipeds in water hearing specialists (Clark and Southall, 2009).

Marine Mammal Vocalization

Marine mammal vocalizations often extend both above and below the range of human hearing (higher than 20 kHz and lower than 20 Hz; Research Council, 2003). Measured data on the hearing abilities of cetaceans are sparse, particularly for the larger cetaceans such as the baleen whales. The auditory thresholds of some of the smaller odontocetes have been determined in captivity. It is generally believed that cetaceans should at least be sensitive to the frequencies of their own vocalizations. Comparisons of the anatomy of cetacean inner ears and models of the structural properties and the response to vibrations of the ear's components in different species provide an indication of likely sensitivity to various sound frequencies. Thus, the ears of small toothed whales are optimized for receiving high-frequency sound, while baleen whale inner ears are best suited for low frequencies, including to infrasonic frequencies (Ketten, 1992; 1997; 1998).

Baleen whale (

i.e.,

mysticete) vocalizations are composed primarily of frequencies below one kHz, and some contain fundamental frequencies as low as 16 Hz (Watkins

et al.,

1987; Richardson

et al.,

1995; Rivers, 1997; Moore

et al.,

1998; Stafford

et al.,

1999; Wartzok and Ketten, 1999) but can be as high as 24 kHz (humpback whale; Au

et al.,

2006). Clark and Ellison (2004) suggested that baleen whales use low frequency sounds not only for long-range communication, but also as a simple form of echo ranging, using echoes to navigate and orient relative to physical features of the ocean. Information on auditory function in mysticetes is limited. Sensitivity to low frequency sound by baleen whales has been inferred from observed vocalization frequencies, observed reactions to playback of sounds, and anatomical analyses of the auditory system. Although there is apparently much variation, the source levels of most baleen whale vocalizations lie in the range of 150-190 dB re: 1 μPa at 1 m. Low-frequency vocalizations made by baleen whales and their corresponding auditory anatomy suggest that they have good low-frequency hearing (Ketten, 2000), although specific data on sensitivity, frequency or intensity discrimination, or localization abilities are lacking. Marine mammals, like all mammals, have typical U-shaped audiograms that begin with relatively low sensitivity (high threshold) at some specified low frequency with increased sensitivity (low threshold) to a species-specific optimum followed by a generally steep rise at higher frequencies (high threshold) (Fay, 1988).

Toothed whales (

i.e.,

odontocetes) produce a wide variety of sounds, which include species-specific broadband “clicks” with peak energy between 10 and 200 kHz, individually variable “burst pulse” click trains, and constant frequency or frequency-modulated (FM) whistles ranging from 4 to 16 kHz (Wartzok and Ketten, 1999). The general consensus is that the tonal vocalizations (whistles) produced by toothed whales play an important role in maintaining contact between dispersed individuals, while broadband clicks are used during echolocation (Wartzok and Ketten, 1999). Burst pulses have also been strongly implicated in communication, with some scientists suggesting that they play an important role in agonistic encounters (McCowan and Reiss, 1995), while others have proposed that they represent “emotive” signals in a broader

sense, possibly representing graded communication signals (Herzing, 1996). Sperm whales, however, are known to produce only clicks, which are used for both communication and echolocation (Whitehead, 2003). Most of the energy of toothed whales' social vocalizations is concentrated near 10 kHz, with source levels for whistles as high as 100-180 dB re 1 μPa at 1 m (Richardson

et al.,

1995). No odontocete has been shown audiometrically to have acute hearing (less than 80 dB re 1 μPa at 1 m) below 500 Hz (DoN, 2001; Ketten, 1998). Sperm whales produce clicks, which may be used to echolocate (Mullins

et al.,

1988), with a frequency range from less than 100 Hz to 30 kHz and source levels up to 230 dB re 1 μPa at 1 m or greater (Mohl

et al.,

2000).

Potential Effects of the Specified Activity on Marine Mammals and Their Habitat

This section includes a summary and discussion of the ways that components of the specified activities may impact marine mammals and their habitat. The Estimated Take of Marine Mammals section later in this document will include a quantitative analysis of the maximum percentage of the affected stocks that are expected to be taken by the SURTASS LFA activities, but enumeration of takes of individuals is completed annually when the Navy submits their application for LOAs for that year's mission areas. The Negligible Impact Analysis and Determination section will consider the content of this section, the Estimated Take of Marine Mammals section, and the Proposed Mitigation section to draw conclusions regarding the likely impacts of these activities on the reproductive success or survivorship of individuals and how those impacts on individuals are likely to impact marine mammal species or stocks.

The Navy has requested authorization for the incidental take of marine mammals that may result from upcoming use of SURTASS LFA sonar by a maximum of four U.S. Naval ships in certain areas of the Pacific, Atlantic, and Indian Oceans and the Mediterranean Sea. In addition to the use of LFA and HF/M3 sonar, the Navy has analyzed the potential impact of ship strike to marine mammals from SURTASS LFA sonar activities, and, in consultation with NMFS as a cooperating agency for the SURTASS LFA sonar 2016 DSEIS/SOEIS, has determined that take of marine mammals incidental to this non-acoustic component of the Navy's operations is not reasonably likely to occur. Therefore, the Navy has not requested authorization for take of marine mammals that might occur incidental to vessel ship strike. In this document, NMFS analyzes the potential effects on marine mammals from exposure to LFA and HF/M3 sonar, but also includes some additional analysis of the potential impacts from vessel operations.

NMFS' analysis of potential impacts from SURTASS LFA activities is outlined in the next section. NMFS will focus qualitatively on the different ways that SURTASS LFA sonar activities may affect marine mammals (some of which may not be classifiedas takes). Then, in the Estimated Take of Marine Mammals section, NMFS will relate the potential effects to marine mammals from SURTASS LFA sonar activities to the MMPA definitions of take, including Level A and Level B Harassment.

The potential effects to marine mammals described in the following sections do not take into consideration the proposed mitigation and related monitoring measures described later in this document (see the Proposed Mitigation section) which, as noted, are designed to effect the least practicable adverse impact on affected marine mammals species and stocks.

Potential Effects of Exposure to SURTASS LFA Sonar Activities

The potential effects of sound from the proposed activities associated with SURTASS LFA sonar might include one or more of the following: Behavioral changes, masking, non-auditory injury (

i.e.,

gas bubble formation/rectified diffusion), and noise-induced loss of hearing sensitivity (more commonly called threshold shift). NMFS discusses these potential effects in more detail below.

The effects of underwater noise on marine mammals are highly variable, and one can categorize the effects as follows (Richardson

et al.,

1995; Nowacek

et al.,

2007; Southall

et al.,

2007):

(1) The noise may be too weak to be heard at the location of the animal (

i.e.,

lower than the prevailing ambient noise level, the hearing threshold of the animal at relevant frequencies, or both);

(2) The noise may be audible but not strong enough to elicit any overt behavioral response;

(3) The noise may elicit behavioral reactions of variable conspicuousness and variable relevance to the well-being of the animal. These can range from temporary alert responses to active avoidance reactions such as vacating an area at least until the noise event ceases, but potentially for longer periods of time;

(4) Upon repeated exposure, a marine mammal may exhibit diminishing responsiveness (habituation), disturbance effects may persist, or disturbance effects could increase (sensitization, or becoming more sensitive to exposure). Persistent disturbance and sensitization are more likely with sounds that are highly variable in characteristics, infrequent, and unpredictable in occurrence, and associated with situations that the animal perceives as a threat (animals are not likely to be exposed enough to SURTASS LFA sonar to exhibit habituation or increased sensitization, due to the fact that SURTASS LFA sonar is a mobile source operating in open water, and animals are likely to move away and/or would not be receiving pings in the way that small resident populations would receive with a stationary source);

(5) Any anthropogenic (human-made) noise that is strong enough to be heard has the potential to reduce the ability of a marine mammal to hear natural sounds at similar frequencies (masking), including calls from conspecifics (

i.e.,

an organism of the same species), and underwater environmental sounds such as surf noise;

(6) If mammals remain in an area because it is important for feeding, breeding, or some other biologically important purpose even though there is a chronic exposure to noise, it is possible that there could be noise-induced physiological stress. This might in turn have negative effects on the well-being or reproduction of the animals involved; and

(7) Very strong sounds have the potential to cause temporary or permanent reduction in hearing sensitivity, also known as threshold shift. In terrestrial mammals and presumably marine mammals, received sound levels must far exceed the animal's hearing threshold for there to be any temporary threshold shift (TTS) in its hearing ability. For transient sounds, the sound level necessary to cause TTS is inversely related to the duration of the sound. Received sound levels must be even higher for there to be the possibility of permanent hearing impairment. In addition, intense acoustic or explosive events (not relevant for this proposed activity) may cause trauma to tissues associated with organs vital for hearing, sound production, respiration and other functions. This trauma may include minor to severe hemorrhage.

Direct Physiological Effects

Threshold Shift (Noise-Induced Loss of Hearing)

When animals exhibit reduced hearing sensitivity within their auditory range (

i.e.,

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

i.e.,

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

i.e.,

an animal might only have a temporary loss of hearing sensitivity within a limited frequency band of its auditory range), and can be of varying amounts (for example, an animal's hearing sensitivity might be reduced by only six dB or reduced by 30 dB). PTS is permanent (

i.e.,

there is incomplete recovery back to baseline/pre-exposure levels), but also can occur in a specific frequency range and amount as mentioned above for TTS.

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

et al.,

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

et al.,

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

et al.,

2009a and 2009b; Kastak

et al.,

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

et al.,

1966; Ward, 1997; Mooney

et al.

2009a, 2009b; Finneran

et al.

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

et al.

1987). However, in the case of the proposed SURTASS LFA sonar activities, animals are not expected to be exposed to levels high enough or durations long enough to result in PTS due to the nature of the activities. The potential for PTS becomes even more unlikely when mitigation measures are considered.

PTS is considered auditory injury (Southall

et al.,

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

et al.,

2007).

Although the published body of scientific literature contains numerous theoretical studies and discussion papers on hearing impairments that can occur with exposure to a loud sound, only a few studies provide empirical information on the levels at which noise-induced loss in hearing sensitivity occurs in nonhuman animals. The NMFS 2016 Acoustic Technical Guidance, which was used in the assessment of effects for this action, compiled, interpreted, and synthesized the best available scientific information for noise-induced hearing effects for marine mammals to derive updated thresholds for assessing the impacts of noise on marine mammal hearing, as noted above. For cetaceans, published data on the onset of TTS are limited to the captive bottlenose dolphin, beluga, harbor porpoise, and Yangtze finless porpoise (summarized in Finneran, 2015). TTS studies involving exposure to SURTASS LFA or other low-frequency sonar (below 1 kHz) have never been conducted due to logistical difficulties of conducting experiments with low frequency sound sources. However, there are TTS measurements for exposures to other LF sources, such as seismic airguns. Finneran

et al.

(2015) suggest that the potential for airguns to cause hearing loss in dolphins is lower than previously predicted, perhaps as a result of the low-frequency content of airgun impulses compared to the high-frequency hearing ability of dolphins. For pinnipeds in water, measurements of TTS are limited to harbor seals, elephant seals, and California sea lions (summarized in Finneran, 2015).

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

i.e.,

recovery time), and frequency range of TTS, and the context in which it is experienced, TTS can have effects on marine mammals ranging from discountable to serious similar to those discussed in auditory masking, below. For example, a marine mammal may be able to readily compensate for a brief, relatively small amount of TTS in a non-critical frequency range that takes place during a time when the animal is traveling through the open ocean, where ambient noise is lower and there are not as many competing sounds present. Alternatively, a larger amount and longer duration of TTS sustained during a time when communication is critical for successful mother/calf interactions could have more serious impacts if it were in the same frequency band as the necessary vocalizations and of a severity that impeded communication. The fact that animals exposed to high levels of sound that would be expected to result in this physiological response would also be expected to have behavioral responses of a comparatively more severe or sustained nature is potentially more significant than simple existence of a TTS. However, it is important to note that TTS could occur due to longer exposures to sound at lower levels so that a behavioral response may not be elicited.

Depending on the degree and frequency range, the effects of PTS on an animal could also range in severity, although it is considered generally more serious than TTS because it is a

permanent condition. Of note, reduced hearing sensitivity as a simple function of aging has been observed in marine mammals, as well as humans and other taxa (Southall

et al.,

2007), so we can infer that strategies exist for coping with this condition to some degree, though likely not without some cost to the animal. There is no empirical evidence that exposure to SURTASS LFA sonar can cause PTS in any marine mammals, especially given the proximity to and duration that an animal would need to be exposed; instead the possibility of PTS has been inferred from studies of TTS on captive marine mammals (see Richardson

et al.,

1995).

As stated in the Navy's DSEIS/SOEIS (section 4.2.3), results show that all hearing groups except LF cetaceans would need to be within 22 ft (7 m) for an entire LFA transmission (60 seconds) to potentially experience PTS. A LF cetacean would need to be within 135 ft (41 m) for an entire LFA transmission to potentially experience PTS. Based on the mitigation procedures used during SURTASS LFA sonar activities, and the fact that animals can be expected to move away from any disturbance, the chances of this occurring are negligible.

Acoustically Mediated Bubble Growth

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

e.g.,

beaked whales) are theoretically predicted to induce greater supersaturation (Houser

et al.,

2001b). A study of repetitive diving in trained bottlenose dolphins found no increase in blood nitrogen levels or formation of bubbles (Houser

et al.,

2009). If rectified diffusion were possible in marine mammals exposed to high-level sound, conditions of tissue supersaturation could theoretically speed the rate and increase the size of bubble growth. Subsequent effects due to tissue trauma and emboli would presumably mirror those observed in humans suffering from decompression sickness.

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

ex vivo

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

et al.,

2005). Furthermore, tissues in the study were supersaturated by exposing them to pressures of 400-700 kiloPascals for periods of hours and then releasing them to ambient pressures. Assuming the equilibration of gases with the tissues occurred when the tissues were exposed to high pressures, levels of supersaturation in the tissues could have been as high as 400-700 percent. These levels of tissue supersaturation are substantially higher than model predictions for marine mammals (Houser

et al.,

2001; Saunders

et al.,

2008). Both the degree of supersaturation and exposure levels observed to cause microbubble destabilization are unlikely to occur, either alone or in concert.

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

et al.,

2003; Fernandez

et al.,

2005; Fernandez

et al.,

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

et al.

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

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

et al.,

2006; Rommel

et al.,

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

i.e.,

rectified diffusion). Work conducted by Crum

et al.

(2005) demonstrated the possibility of rectified diffusion for short duration signals, but at exposure levels and tissue saturation levels that are highly improbable to occur in diving marine mammals. To date, energy levels predicted to cause in vivo bubble formations within diving cetaceans have not been evaluated (NOAA, 2002b). Although it has been argued that traumas from some beaked whale strandings are consistent with gas emboli and bubble-induced tissue separations (Jepson

et al.,

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

et al.,

2006). However, Jepson

et al.

(2003, 2005) and Fernandez

et al.

(2004, 2005, 2012) concluded that in vivo bubble formation, which may be exacerbated by deep, long-duration, repetitive dives, may explain why beaked whales appear to be particularly vulnerable to MF/HF active sonar exposures. This has not been demonstrated for LF sonar exposures, such as SURTASS LFA sonar.

In 2009, Hooker

et al.

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

N2

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

N2

levels and thereby decompression sickness risk between species.

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

et al.,

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

N2

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

N2

than body mass differences between species. Despite diel changes (

i.e.,

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

N2

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

N2

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

and blood N2 levels (Hooker

et al.,

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

et al.,

2009).

Bernaldo de Quiros

et al.

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

et al.

(2012) estimated blood and tissue P

N2

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

2

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

et al.

(2014) evaluated dive data recorded from sperm, killer, long-finned pilot, Blainville's beaked and Cuvier's beaked whales before and during exposure to low (1-2 kHz) and mid (2-7 kHz) frequency active sonar (note that SURTASS LFA sonar is transmitted between 100-500 Hz, which is well below the low frequency sonar in these studies) in an attempt to determine if either differences in dive behavior or physiological responses to sonar are plausible risk factors for bubble formation. The authors suggested that CO

2

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

2

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

2

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

2

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

et al.

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

2.

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

2

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

et al.,

2006; Southall

et al.,

2007; Zimmer and Tyack, 2007; Baird

et al.,

2008; Hooker

et al.,

2009). Further investigation is needed to assess the potential validity of these hypotheses. However, because SURTASS LFA sonar transmissions are lower in frequency (less than 500 Hz) and dissimilar in characteristics from those of marine mammal predators the SURTASS LFA sonar transmissions are not expected to cause gas bubble formation or beaked whale strandings.

To summarize, there are few data related to the potential for strong, anthropogenic underwater sounds to cause non-auditory physical effects in marine mammals. Such effects, if they occur at all, would presumably be limited situations where marine mammals were exposed to high powered sounds at close range over a prolonged period of time. The available data do not allow identification of a specific exposure level above which non-auditory effects can be expected (Southall

et al.,

2007) or any meaningful quantitative predictions of the numbers (if any) of marine mammals that might be affected in those ways.

Acoustic Masking

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

The extent of the masking interference depends on the spectral, temporal, and spatial relationships between the signals an animal is trying to receive and the masking noise, in addition to other factors. In humans, significant masking of tonal signals occurs as a result of exposure to noise in a narrow band of similar frequencies. As the sound level increases, the detection of frequencies above those of the masking stimulus decreases. This principle is expected to apply to marine mammals as well because of common biomechanical cochlear properties across taxa.

Richardson

et al.

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

i.e.,

surf noise, prey noise, etc.) (Richardson

et al.,

1995).

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

i.e.,

upward masking). Studies on captive odontocetes by Au

et al.

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

e.g.,

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

et al.,

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

et al.

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

et al.,

2005).

Parks

et al.

(2007) provided evidence of behavioral changes in the acoustic behaviors of the endangered North Atlantic right whale, and the South Atlantic right whale, and suggested that these were correlated to increased underwater noise levels. The study indicated that right whales might shift the frequency band of their calls to compensate for increased in-band background noise. The significance of their result is the indication of potential species-wide behavioral change in response to gradual, chronic increases in underwater ambient noise. Di Iorio and Clark (2010) showed that blue whale calling rates vary in association with seismic sparker survey activity, with whales calling more on days with

survey than on days without surveys. They suggested that the whales called more during seismic survey periods as a way to compensate for the elevated noise conditions.

Risch

et al.

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

et al.,

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

et al.,

2012). Thus, the novelty of the sound to humpback whales in the study area provided a compelling contextual probability for the observed effects (Risch

et al.,

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

et al.,

2012).

Redundancy and context can also facilitate detection of weak signals. These phenomena may help marine mammals detect weak sounds in the presence of natural or manmade noise. Most masking studies in marine mammals present the test signal and the masking noise from the same direction. The sound localization abilities of marine mammals suggest that, if signal and noise come from different directions, masking would not be as severe as some masking studies might suggest (Richardson

et al.,

1995). The dominant background noise may be highly directional if it comes from a particular anthropogenic source such as a ship or industrial site. Directional hearing may significantly reduce the masking effects of these sounds by improving the effective signal-to-noise ratio.

As mentioned previously, the hearing ranges of mysticetes overlap with the frequencies of the SURTASS LFA sonar sources. The closer the characteristics of the masking signal to the signal of interest, the more likely masking is to occur. The Navy provided an analysis of marine mammal hearing and masking in Subchapter 4.2.2.1.4 of the DSEIS/SOEIS, and the masking effects of the SURTASS LFA sonar signal are expected to be limited for a number of reasons. First, the frequency range (bandwidth) of the system is limited to approximately 30 Hz, and the instantaneous bandwidth at any given time of the signal is small, on the order of 10 Hz. Second, the average duty cycle is always less than 20 percent and, based on past SURTASS LFA sonar operational parameters (2003 to 2016), is normally 7.5 to 10 percent. Third, given the average maximum pulse length (60 sec), and the fact that the signals vary and do not remain at a single frequency for more than 10 sec, SURTASS LFA sonar is not likely to cause significant masking. In other words, the LFA sonar transmissions are coherent, narrow bandwidth signals of six to 100 sec in length followed by a quiet period of six to 15 minutes. Therefore, the effect of masking will be limited because animals that use this frequency range typically use broader bandwidth signals. As a result, the chances of an LFA sonar sound actually overlapping whale calls at levels that would interfere with their detection and recognition will be extremely low.

Impaired Communication

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

et al.,

2004; Lohr

et al.,

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

et al.,

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

et al.,

2006). Most species that vocalize are able to adapt by adjusting their vocalizations to increase the signal-to-noise ratio, active space, and recognizability/distinguishability of their vocalizations in the face of temporary changes in background noise (Brumm

et al.,

2004; Patricelli

et al.,

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

Many animals will combine several of these strategies to compensate for high levels of background noise. Anthropogenic sounds which reduce the signal-to-noise ratio of animal vocalizations, increase the masked auditory thresholds of animals listening for such vocalizations, or reduce the active space of an animal's vocalizations impair communications between animals. Most animals that vocalize have evolved strategies to compensate for the effects of short-term or temporary increases in background or ambient noise on their songs or calls. Although the fitness consequences of these vocal adjustments are not directly known in all instances, like most other trade-offs animals must make, some of these strategies probably come at a cost (Patricelli

et al.,

2006). Shifting songs and calls to higher frequencies may also impose energetic costs (Lambrechts, 1996). For example in birds, vocalizing more loudly in noisy environments may have energetic costs that decrease the net benefits of vocal adjustment and alter a bird's energy budget (Brumm, 2004; Wood and Yezerinac, 2006).

Stress Responses

Classic stress responses begin when an animal's central nervous system perceives a potential threat to its

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