# Taking and Importing Marine Mammals; Taking Marine Mammals Incidental to Navy Operations of Surveillance Towed Array Sensor System Low Frequency Active Sonar

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URL: https://www.frixlaw.com/law-library/documents/fr%3A02-16853

## Record

- **Collection:** Federal Register
- **Document type:** Rule
- **Published:** July 16, 2002
- **Citation:** 67 FR 46712

## Text

DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
50 CFR Part 216
[Docket No. 990927266-2137-03; I.D. 072699A]
RIN 0648-AM62
Taking and Importing Marine Mammals; Taking Marine Mammals Incidental to 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:

Final rule.

SUMMARY:

NMFS, upon application from the U.S. Navy, is issuing regulations to govern the unintentional takings of small numbers of marine mammals incidental to Navy operation of the Surveillance Towed Array Sensor System (SURTASS) Low Frequency Active (LFA) Sonar. Issuance of regulations, and Letters of Authorization under these regulations, governing unintentional incidental takes of marine mammals in connection with particular activities is required by the Marine Mammal Protection Act (MMPA) when the Secretary of Commerce (Secretary), after notice and opportunity for comment, finds, as here, that such takes will have a negligible impact on the species and stocks of marine mammals and will not have an unmitigable adverse impact on the availability of them for subsistence uses. These regulations do not authorize the Navy's operation of SURTASS LFA sonar as such authorization is not within the jurisdiction of the Secretary. Rather, these regulations authorize the unintentional incidental take of marine mammals in connection with this activity and prescribe methods of taking and other means of effecting the least practicable adverse impact on marine mammal species and their habitat, and on the availability of the species for subsistence uses.

DATES:

Effective from August 15, 2002 through August 15, 2007.

ADDRESSES:

A copy of the Navy application and a list of references used in this document may be obtained by writing to Donna Wieting, Chief, Marine Mammal Conservation Division, Office of Protected Resources, National Marine Fisheries Service, 1315 East-West Highway, Silver Spring, MD 20910-3226 or by telephoning the contact listed here (see
FOR FURTHER INFORMATION CONTACT
). The NMFS' Administrative Record for this action is available for viewing, by appointment during regular business hours, at the above address. Copies of letters, documents and the public hearing record are available, at copy cost, from this address.

Comments regarding the burden-hour estimate or any other aspect of the collection of information requirement contained in this final rule should be sent to the Chief, and to the Office of Information and Regulatory Affairs, Office of Management and Budget (OMB), Attention: NOAA Desk Officer, Washington, DC 20503.

FOR FURTHER INFORMATION CONTACT:

Kenneth R. Hollingshead (301) 713-2322, ext. 128.

SUPPLEMENTARY INFORMATION:

Background

Section 101(a)(5)(A) of the Marine Mammal Protection Act (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 by U.S. citizens who engage in a specified activity (other than commercial fishing) within a specified geographical region if certain findings are made and regulations are issued.

Permission may be granted for periods of 5 years or less if the Secretary finds that the taking will be small, have a negligible impact on the species or stock(s) of affected marine mammals, and will not have an unmitigable adverse impact on the availability of the species or stock(s) for subsistence uses, and if regulations are prescribed setting forth the permissible methods of taking and the requirements pertaining to the monitoring and reporting of such taking.

Summary of Request

On August 12, 1999, NMFS received an application from the U.S. Navy requesting a small take exemption under section 101(a)(5)(A) of the MMPA for the taking of marine mammals incidental to deploying the SURTASS LFA sonar system for training, testing and routine military operations anywhere within the world's oceans (except for Arctic and Antarctic waters) for a period of time not to exceed 5 years. According to the original Navy application, SURTASS LFA sonar would operate a maximum of 4 ship systems in the 10 geographic operating regions in which SURTASS LFA sonar could potentially operate. There would be a maximum of four SURTASS LFA sonar systems with an expected maximum of two systems at sea at any one time.

The purpose of SURTASS LFA sonar is to provide the Navy with a reliable and dependable system for long-range detection of quieter, harder-to-find submarines. Low-frequency (LF) sound travels in seawater more effectively and for greater distances than higher frequency sound used by most other active sonars. According to the Navy, the SURTASS LFA sonar system would meet the Navy's need for improved detection and tracking of new-generation submarines at a longer range. This 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.

Description of the Activity

The SURTASS LFA sonar system is a long-range, LF sonar (between 100 and 500 Hertz) that has both active and passive components. It does not rely on detection of noise generated by the target. The active component of the system is a set of up to 18 LF acoustic transmitting source elements (called projectors) suspended from a cable from underneath a ship. The projectors are devices that transform electrical energy to mechanical energy by setting up vibrations, or pressure disturbances with the water to produce the pulse or ping. The SURTASS LFA sonar acoustic transmission is an omnidirectional (full 360 degrees) beam in the horizontal. The expected water depth of the center of the array is 400 ft (122 m), with a narrow vertical beamwidth that can be steered above or below the horizontal. The source level (SL) of an individual projector in the SURTASS LFA sonar array is approximately 215 dB, and because of the physics involved in beam forming and transmission loss processes, the array can never have a sound pressure level (SPL) higher than the SPL of an individual projector. The expected minimum water depth at which the SURTASS LFA vessel will operate is 200 m (656.2 ft). Normally, the shallowest depth that it can operate is 100 m (328.1 ft).

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 is referred to by the Navy as a “ping” and can last as short as 6 seconds (sec) to as long as 100 sec, normally with no more than 10 seconds at any single frequency. The time

between pings is typically from 6 to 15 minutes. Average duty cycle (ratio of sound “on” time to total time) can be controlled but cannot be greater than 20 percent; typical duty cycle is between 10 and 15 percent.

The passive or listening component of the system is SURTASS, which detects returning echoes from submerged objects, such as submarines, through the use of hydrophones. The hydrophones are mounted on a horizontal array that is towed behind the ship. The SURTASS LFA sonar ship maintains a minimum speed of 3.0 knots (5.6 km/hr; 3.4 mi/hr) in order to keep the array deployed.

The Navy anticipates that a normal SURTASS LFA sonar deployment schedule for a single vessel would involve about 270 days/year at sea (underway). A normal at-sea mission would occur over a 30-day period, made up of two 9-day exercise segments. The remaining 12 days of the at-sea mission would be spent in transit or repositioning the vessel. In an average year there could be a maximum of 9 missions, six of which would involve the employment of SURTASS LFA sonar in the active mode and three of which would employ the SURTASS LFA sonar in the passive mode only. Active sonar operations could be conducted up to 20 hrs during an exercise day, although the system would actually be transmitting for only a maximum of 4 hrs/day (resulting in 432 hrs of active transmission time per year for each SURTASS LFA sonar system in operation based on a maximum duty cycle of 20 percent). Between missions, an estimated 95 days would be spent in port for upkeep and repair.

At present, only one SURTASS LFA sonar system is available for deployment. A second SURTASS LFA sonar system is expected to be available shortly. Delivery of the third and fourth systems have been postponed until after FY 2007. As a result, under the 5-year window of these regulations, NMFS is authorizing marine mammal harassment takings for only 2 SURTASS LFA sonar systems, on average with one vessel operating in the Pacific-Indian Ocean area and one vessel in the Atlantic Ocean-Mediterranean Sea area. With two vessels, there would normally be 6 SURTASS LFA sonar missions in each of these oceanic basins (or equivalent shorter missions totaling no more than 432 hours of transmission/vessel/ year), or a total of 12 active sonar missions per year over the 5-year period of the regulations.

Description of Acoustic Propagation

The following is a very basic and generic description of the propagation of LFA sonar signals in the ocean and is provided to facilitate understanding of this action. However, because the actual physics governing the propagation of SURTASS LFA sound signals is extremely complex and dependent on numerous in-situ environmental factors, the following is for illustrative purposes only.

In actual SURTASS LFA sonar operations, the crew of the SURTASS LFA sonar platform will measure oceanic conditions (such as sea water temperature and salinity versus depth) prior to and during transmissions and at least every 12 hours, but more frequently when meteorological or oceanographic conditions change. These technicians will then use U.S. Navy sonar propagation models to predict and/or update sound propagation characteristics. According to the Navy, these extremely sophisticated computer simulations are among the most accurate in the world. The short time periods between actual environmental observations and the subsequent model runs further enhance the accuracy of these predictions. Fundamentally these models are used to determine what path the LF signal will take as it travels through the ocean and how strong the sound signal will be at given range along a particular transmission path.

Accurately determining the speed at which sound travels through the water is critical to predicting the path that sound will take. The speed of sound in seawater varies directly with depth, temperature, and salinity. Thus, an increase in depth or temperature or, to a lesser degree, salinity will increase the speed of sound in seawater. However, the oceans are not homogeneous and the contribution of each of these individual factors is extremely complex and interrelated. The physical characteristics which determine the sound speed change with depth (in the case of temperature and salinity), season, geographic location, and locally, with time of day. After accurately measuring these factors, mathematical formulas or models can be used to generate a plot of sound speed versus water depth. This type of plot is generally referred to as a sound speed profile (SSP). Near the surface, ocean water mixing results in a fairly constant temperature and salinity. In this mixed layer, depth (pressure) dominates the SSP and sound speed
increases
with depth. Below the mixed layer, sea temperature drops rapidly in an area referred to as the thermocline. In this region, temperature dominates the SSP and speed
decreases
with depth. Finally, beneath the thermocline, the temperature becomes fairly uniform and increasing pressure causes the SSP to
increase
with depth.

One way to envision sound traveling though the sea is to think of the sound as “rays.” As these rays travel though the sea, their direction of travel changes as a result of speed changes, bending or refracting toward areas of lower speed and away from areas of higher speed. Depending on environmental conditions, refraction can either be toward or away from the surface. Additionally, the rays can be reflected or absorbed when they encounter the surface or the bottom. Under the correct environmental conditions, sound rays can repeatedly be refracted upward and downward and thus become trapped in a duct or “sound channel.” Similarly, reflections from the surface or the bottom can combine with refraction to create a duct. In the right circumstances, repeated refraction can result in long-range focusing and defocusing of the sound. Because of the possibility of multiple transmission paths, all of which are dependent on environmental conditions, accurate predictions of how sound travels in water is an extremely complex process.

Some of the more prevalent acoustic propagation paths in the ocean include: acoustic ducting; convergence zone (CZ); bottom interaction; and shallow-water propagation.

Acoustic Ducting

There are two types of acoustic ducting: surface ducts and sound channels.

Surface Ducts

As previously discussed, the top layer of the ocean is normally well mixed and has relatively constant temperature and salinity. Because of the effect of depth (pressure), surface layers exhibit a slightly positive sound speed gradient (that is, sound speed increases with depth). Thus, sound transmitted within this layer is refracted upward toward the surface. If sufficient energy is subsequently reflected downward from the surface, the sound can become “trapped” by a series of repeated upward refractions and downward reflections. Under these conditions, a surface duct, or surface channel is said to exist. Sound trapped in a surface duct can travel for relatively long distances with its maximum range of propagation dependent on the specifics of the SSP, the frequency of the sound, and the reflective characteristics of the surface. As a general rule, surface duct

propagation will improve as the temperature uniformity and depth of the layer increase. For example, transmission is improved when cloudy, windy conditions create a well-mixed surface layer or in high-latitude midwinter conditions where the mixed layer extends to several hundred feet deep.

Sound Channels

Variation of sound speed, or velocity, with depth causes sound to travel in curved paths. A sound channel is a region in the water column where sound speed first decreases with depth to a minimum value, and then increases. Above the depth of minimum value, sound is refracted (bent) downward; below the depth of minimum value, sound is refracted upward. Thus, much of the sound starting in the channel is trapped, and any sound entering the channel from outside its boundaries is also trapped. This mode of propagation is called sound channel propagation. This propagation mode experiences the least transmission loss along the path, thus resulting in long-range transmission.

At low and middle latitudes, the deep sound channel axis varies from 1,970 to 3,940 ft (600 to 1,200 m) below the surface. It is deepest in the subtropics and comes to the surface in the high latitudes, where sound propagates in the surface layer. Because propagating sound waves do not interact with either the sea surface or seafloor, sound propagation in sound channels do not attenuate as rapidly as bottom- or surface-interacting paths. The most common sound channels used by SURTASS LFA sonar are convergence zones (CZs).

Convergence Zones

CZs are special cases of the sound-channel effect. When the surface layer is narrow or when sound rays are refracted downward, regions are created at or near the ocean surface where sound rays are focused, resulting in concentrated levels of high sounds. The existence of CZs depends on the SSP and the depth of the water. Due to downward refraction at shorter ranges, sound rays leaving the near-surface region are refracted back to the surface because of the positive sound speed gradient produced by the greater pressure at deep ocean depths. These deep-refracted rays often become concentrated at or near the surface at some distance from the sound source through the combined effects of downward and upward refraction, thus causing a CZ. CZs may exist whenever the sound speed at the ocean bottom, or at a specific depth, exceeds the sound speed at the source depth. Depth excess, also called sound speed excess, is the difference between the bottom depth and the limiting, or critical depth.

CZs vary in range from approximately 18 to 36 nm (33 to 67 km), depending upon the SSP. The width of the CZ is a result of complex interrelationships and cannot be correlated with any specific factor. In practice, however, the width of the CZ is usually on the order of 5 to 10 percent of the range (see Figure 1). For optimum tactical performance, CZ propagation of SURTASS LFA signals is desired and expected in open ocean conditions.

BILLING CODE 3810-FF-P

ER16JY02.000

BILLING CODE 3810-FF-C

Bottom Interaction

Reflections from the ocean bottom and refraction within the bottom can extend propagation ranges. For mid- to high-level frequency sonars (greater than 1,000 Hz), only minimal energy enters into the bottom; thus reflection is the predominant mechanism for energy return. However, at low frequencies, such as those used by the SURTASS LFA sonar source, the sound penetrates the ocean floor, and refraction within the seafloor, not reflection, dominates the energy return. Regardless of the actual transmission mode (reflection from the bottom or refraction within the bottom), this interaction is generally referred to as “bottom-bounce” transmission.

Major factors affecting bottom-bounce transmission include the sound frequency, water depth, angle of incidence, bottom composition, and bottom roughness. A flat ocean bottom produces the greatest accuracy in estimating range and bearing in the bottom-bounce mode.

For SURTASS LFA sonar transmissions between 100 and 330 Hz, bottom interaction would generally occur in areas of the ocean where depths are between approximately 200 m (average minimum water depth for SURTASS LFA sonar deployment) and 2,000 m (660 and 6,600 ft).

Shallow Water Propagation

In shallow water, propagation is usually characterized by multiple reflection paths off the sea floor and sea surface. Thus, most of the water column tends to become ensonified by these overlapping reflection paths. As LFA signals approach the shoreline, they will be affected by shoaling, experiencing high transmission losses through bottom and surface interactions. Therefore, LFA sonar will not be effective in shallow, coastal waters.

In summary, for the SURTASS LFA sonar signal in low- and mid-latitudes, the dominant propagation paths for LFA signals are CZ and bottom interaction (<2000 m (6,600 ft) depth). In high-latitudes, surface ducting provides the best propagation. In most open ocean water, CZ propagation will be most prominent. An example of this propagation path is shown in Figure 1. The SURTASS LFA sonar signals will interact with the bottom, but due to high bottom and surface losses, SURTASS LFA sonar signals will not penetrate coastal waters with appreciable signal strengths.

Comments and Responses

On October 22, 1999 (64 FR 57026), NMFS published an Advance Notice of Proposed Rulemaking (ANPR) on the U.S. Navy application and invited interested persons to submit comments, information, and suggestions concerning the application and the structure and content of regulations, if the application was accepted. During the 30-day comment period of that notification, significant comments were received from several organizations and individuals. On March 19, 2001 (66 FR 15375), NMFS published a proposed rule to authorize the U.S. Navy to take small numbers of marine mammals incidental to operation of SURTASS LFA sonar and requested comments, information, and suggestions concerning the request and the regulations proposed to govern the take. The comments provided to NMFS during the ANPR's comment period were addressed in the notice of proposed rulemaking. A copy of the proposed rulemaking document is available at:
http://www.nmfs.noaa.gov/prot_res/PR2/Acoustics_Program/acoustics.html

While the comment period on the proposed rule was for a period of 45 days, the comment period was extended until May 31, 2001, a period of 73 days (66 FR 26828, May 15, 2001). During that time period, NMFS received several thousand comments from organizations and interested citizens. Most of the comments received were petitions, postcards and form letters, either mailed or faxed to NMFS. Approximately 87 letters contained comments, information, and questions that NMFS determined warranted response in this document. Moreover, these letters reflected the same comments that were contained in the other letters and postcards, but in greater detail. They are available for viewing at the following location:
http://fish.nmfs.noaa.gov/ibrm/OPRComments.lhtml?rulein=2
. For those without access to the Internet, copies of these letters and all comments received by NMFS are available from NMFS at copy cost (see
ADDRESSES
).

In addition to written comments, NMFS held three public hearings to obtain oral and written information from the public on NMFS' proposed rule (66 FR 19414, April 16, 2001). These public hearings were held in Los Angeles, CA on April 26, 2001, Honolulu, HI on April 28, 2001, and Silver Spring, MD on May 3, 2001. A copy of any or all of the hearing records is also available from NMFS at copy cost (see
ADDRESSES
).

In this document, NMFS has (1) provided response to comments (RTCs) on both its proposed rule and the Navy's Final EIS; (2) provided cross-references to the appropriate response in the Navy's Final Overseas Environmental Impact Statement and Environmental Impact Statement for SURTASS LFA Sonar (Final EIS) for comments that were addressed in the Navy's Final EIS; (3) edited some comments for clarity and brevity; and (4) grouped similar comments or chosen one or two comments to represent several similar comments. Some comments may not have been addressed because their meaning or relevance was not clear.

In the following sections, NMFS is responding to comments on the Navy activity whether or not the comment was relevant to the Navy's application or the effect of SURTASS LFA sonar on marine mammals and thereby under the purview of NMFS. This was done to further facilitate understanding of the Navy's proposed action, the alternatives identified by the public to SURTASS LFA sonar, and the potential impact of SURTASS LFA sonar on marine mammals.

Activity Concerns (AC)

Comment AC1:
The Cold War is over. With no threat from the Russians, why is LFA needed?

Response:
It is the opinion of the Navy that the end of the Cold War doesn't end the need for naval surveillance. On 11 October 2001, in testimony before the Subcommittee on Fisheries Conservation, Wildlife and Oceans of the House Committee on Resources on the MMPA and SURTASS LFA Sonar, Vice-Admiral Dennis V. McGinn, the Deputy Chief of Naval Operations for Warfare Requirements and Programs made the following statement concerning the need for SURTASS LFA sonar:

The Navy has an immediate, critical need for SURTASS LFA. By law, the Navy's primary mission is to maintain, train and equip combat-ready Naval forces capable of winning wars, deterring aggression and maintaining freedom of the seas. Antisubmarine warfare, or ASW, is a critical part of that mission. The Chief of Naval Operations (CNO) has stated that ASW is essential to sea control and maritime dominance. Many nations throughout the world can employ submarines to deny access to forward regions or to significantly delay the execution of crucial Navy operations. Because of its inherent stealth, lethality, and affordability, the submarine is a powerful threat. In 1998 the Chief of Naval Operations emphasized the importance of ASW in protecting our national security and set the direction for achieving operational primacy in ASW. He stated that the Navy's goal is to

have the best-trained ASW force in the world, with the right set of tools to prevail in any type of conflict, including the kind we are now facing in the Middle East. My goal here today is to show you why I believe one of the primary ASW tools must be SURTASS LFA.

Comment AC2:
War/heightened tension clause is a major loophole allowing the Navy to operate wherever they want without mitigation. Both the Final EIS and the permitting process should address the use of SURTASS LFA sonar during war, combat, and heightened threat conditions.

Response:
War, combat, and heightened threat conditions are determined by the Congress or the National Command Authorities (NCA), not the U.S. Navy. Chapter 1 (Purpose and Need) and RTC 1-1.7 of the Final EIS identify the NCA as the President and the Secretary of Defense (or their duly designated alternates or successors), as assisted by the Chairman of the Joint Chiefs of Staff. Since these determinations are not made by the Navy, both the small take application and the Navy's Draft and Final EISs are specifically limited to employment of the SURTASS LFA sonar during training, testing, and routine military operations and will not cover use of the SURTASS LFA system in self-defense, in times of war, combat or heightened threat conditions mentioned by the commenter.

The Final EIS does not include use of SURTASS LFA sonar during these conditions because these operations would be speculative at the EIS stage and outside the Navy's control. Moreover, as noted here, the Council on Environmental Quality (CEQ) regulations, Department of Defense (DOD) Directives and Executive Order (E.O.) 12114 provide specific guidance on what to do in emergencies that are not susceptible to the regular NEPA process.

CEQ Regulations For Implementing the Procedural Provisions of the National Environmental Policy Act under 40 CFR 1506.11 concerning “Emergencies” states,

Where emergency circumstances make it necessary to take action with significant environmental impact without observing the provisions of these regulations, the Federal agency taking the action should consult with the Council about alternative arrangements. Agencies and the Council will limit such arrangements to actions necessary to control the immediate impacts of the emergency.

DOD Directive 6050.1, Environmental Effects in the United States of DOD Actions, implements the above CEQ regulations and provide policy and procedures to DOD officials. This directive defines “Emergencies” as they apply to DOD Components to include “actions that must be taken to promote the national defense or security that cannot be delayed, and actions necessary to protect life or property.”

E.O. 12114 (Environmental Effects Abroad of Major Federal Actions) directs federal agencies to provide informed decision-making for actions that have the potential to significantly harm the environment outside U.S. waters and furthers the purposes of NEPA and other statutes in the global commons. E.O. 12114 Section 2-5
Exemptions and Considerations
Subsection (a)(iii) states, “actions taken by or pursuant to the direction of the President or Cabinet officer when national security or interest is involved or when the action occurs in the course of an armed conflict are exempt from the Order.” Because wartime and heightened threat conditions are provided for by a separate process under CEQ Regulations and are exempted from the requirements of E.O. 12114, consideration of these conditions are outside of the scope of the Final EIS. Therefore, NMFS agrees with the Navy that it is appropriate for these conditions not to be addressed in the Navy's Final EIS.

NMFS is not authorizing the incidental taking of marine mammals during periods of war, combat, and heightened threat conditions in its MMPA application because: (1) The Navy did not request an authorization to cover these conditions, (2) the timing of such events is speculative and outside the control of the U.S. Navy, and (3) because the Navy may not be capable of complying with certain conditions (
e.g.,
area of operations and length of mission, and mitigation and monitoring requirements) contained in the regulations and the Letter of Authorization (LOA). In the rare event that any of these conditions was declared and the Navy's SURTASS LFA sonar assets were included in this condition, an LOA would be placed in abeyance until the war, combat, or heightened threat condition was terminated. Upon its conclusion, NMFS would then reassess the impact on marine mammals using information from the activity area(s) and updated modeling results to determine whether the takings in the future would continue to have no more than a negligible impact on affected marine mammal stocks. For example, additional mitigation might be required to ensure that the stocks affected during the heightened threat condition were not additionally impacted during the period of the regulations' effectiveness.

Comment AC3:
A lower-powered, shorter-range system should be used. In a discussion of the supercavitation technology and the Russian Skval torpedo, the commenter stated, “they [the Russians] have also been selling Kilo-Class diesel-electric submarines to nations like North Korea. These submarines are super quiet * * *.”

Response:
According to the Navy, a lower-powered, and thus shorter-range, system will not meet the Navy's stated need for long-range detection of quiet submarines. The latter statement in the comment reinforces the Final EIS Purpose and Need statement for the development of SURTASS LFA sonar technology and the immediate need to be able to detect these quiet submarines at long range.

Comment AC4:
One commenter believes that SPAWAR (Space and Naval Warfare Systems Command) in San Diego (TD3105) stated that SURTASS LFA System was apparently successfully used to locate Soviet submarines during the Cold War.

Response:
The referenced statement by SPAWAR actually stated that the SPAWAR Systems Center focused its efforts on the development of
capabilities
to detect and track Soviet nuclear submarines operating in deep water. It also stated that these efforts (development of capabilities) were successful for several systems, such as SURTASS LFA sonar. SPAWAR did not state that SURTASS LFA sonar was used to
actually
track Soviet submarines during the Cold War.

Comment AC5:
The Final EIS states that SURTASS LFA sonar is needed to protect “choke points” through which international shipping moves. It also states that LFA operations would generally not occur in areas of high human activity such as high shipping density. Also, will LFA be used in the littorals? If so, the EIS claim that near-shore environments will not be the focus of SURTASS LFA appears to be false.

Response:
According to the Navy, SURTASS LFA sonar is a long-range sonar, it does not have to operate in, or near, “choke points” nor close to shore to detect submarines at long range.

SURTASS LFA sonar may support operations that take place in the littoral zone. However, according to the Naval Doctrine Command (1998), littoral zone refers to that area off the coast where naval forces conduct strategic sealift operations, control or interdict sea lines of communication, and project power ashore. The latter objective may entail operations up to approximately 200 nautical miles (nm) (370.4 km) from the coast. However, mitigation measures

prohibit SURTASS LFA sonar from transmitting an SPL greater than 180 dB at a distance of 12 nm (22 km) from any shore.

Comment AC6:
One commenter has described a scenario in which the enemy deploys numerous decoys, or “phantom submarines,” to confuse the SURTASS LFA sonar computer. He also states that merely by transmitting, the LFA vessel will give away its position.

Response:
As stated in the Final EIS (RTC 1-1.6), the SURTASS LFA sonar vessel cannot remain undetected when transmitting, but it will be protected by naval forces. The use of decoys is a standard countermeasure for undersea warfare, one that has been taken into consideration in the planning and design of sonar systems and tactics.

Comment AC7:
Use the military intelligence community to address the diesel submarine threat from rogue nations.

Response:
According to the Navy, the intelligence community does provide the Navy Fleet Commanders-in-Chief with information regarding threat submarines. However, real-time, tactical information is still needed from SURTASS LFA sonar for theater commanders to respond to these threats.

Comment AC8:
SURTASS LFA sonar is the loudest sound ever produced by man. SURTASS LFA sonar will add tremendously to the problem of ocean noise pollution through the use of very high-energy sound blasting coupled with the long-range underwater effects characteristic of LF sound.

Response:
The maximum sound exposure an animal could receive from SURTASS LFA sonar is 215 dB. This is not the loudest sound in the oceans from natural or human sources, nor is it the greatest source of sound energy (in lay terms, the total quantity of sound) in the oceans. Each year billions of lightning strikes hit the ocean with source levels of about 260 dB. Earthquakes and other geological events that exceed 230 dB occur about 1,000 times per year in the Pacific Ocean alone, and 10,000 of them occur that exceed 205 dB. Frankel (1994) estimated the source level for singing humpback whales to be between 170 and 175 dB while Au and Andrews (2001) measured their calls off Hawaii at 189 dB; the average call source level for blue whales was calculated by McDonald
et al.
(2001) to be 186 dB. Watkins
et al.
(1987) and Charif
et al.
(2002) found source levels for fin whales up to 186 dB, and M
0
hl
et al.
(2000) recorded source levels for sperm whale clicks up to 223 dB (rms).

Aside from explosions, the loudest human noise in the oceans is from airgun arrays used in oil and gas exploration. World-wide, there are approximately 150 vessels that conduct these surveys. With source levels of up to 255 dB, and capable of shooting every 10 seconds around the clock, any one of these surveys can put more acoustic energy into the ocean annually than SURTASS LFA sonar. However, the greatest source of sound energy in the oceans caused by humans is from commercial shipping. SURTASS LFA sonar and all other impulsive human noises could be eliminated and noise levels in the oceans would continue to rise because of shipping alone.

Comment AC9:
Provide LFA source level (SL) and attenuation. Define the difference between actual and effective SL of the LFA array. NMFS personnel do not understand that the effective source level of LFAS really is 240 dB. The cumulative sound produced by the LFA array is not limited to the volume of each speaker.

Response:
As stated in the Final EIS (RTC 2-1.1 and 2-1.2), the SL of an individual SURTASS LFA source projector is approximately 215 dB. Because the SURTASS LFA array employs more than one source projector, the effective (not actual) SL of the array is a theoretical calculation based on the sound field beam formed by the array at a range of hundreds of meters from the array, where propagation loss has already caused a decrease in received level (RL) of over 40 dB. Therefore, in the proximity of the SURTASS LFA sonar array, the SL approximates that of an individual projector (215 dB), and the sound field of the array is not higher than the SL of an individual projector. For a more detailed explanation see the Final EIS, Appendix B, Subchapter B.3.1.

Comment AC10:
The Navy stated that LFA intensities under 215 dB will not “fulfill the purpose.” Therefore, there is the likelihood that higher levels will be used during actual military operations. Source level of 215 dB is neither necessary nor desirable. Source levels can be reduced by using: (1) longer duration source signals, (2) replacing single array with multiple arrays, and (3) multi-ship arrays.

Response:
According to the Navy, in order to meet the requirement for long-range detection, 215 dB SL is necessary. There will be no transmission levels of greater than 215 dB for each projector. The three items mentioned by the commenter will not reduce the SLs. These items are already part of ASW operations. First, long duration signals of up to a 100-second duration are used by SURTASS LFA sonar. Second, a new twin line SURTASS passive array is being developed to improve detection and will be used with SURTASS LFA sonar. Finally, multiple-ship receive arrays are used. Passive-only SURTASS vessels can be used to receive the SURTASS LFA signal from vessels with the active (LFA) component installed. See the Final EIS (RTC 1-1.3) for more information.

Comment AC11:
Passive alternatives to SURTASS LFA sonar (
e.g.
, ADS (Advanced Deployable System), Twin Line SURTASS, Acoustic Rapid Commercial-off-the-shelf Insertion (ARCI) processing, Robust Passive Sonar, “Acoustic daylight” technology) were not considered.

Response:
Passive alternatives to SURTASS LFA sonar are discussed in the Final EIS (RTCs 1-2.1, 1-2.2, and 1-2.3). Effective ASW operations require the ability of Fleet Commanders-in-Chief to balance many variable factors, both tactical and environmental, to provide the acceptable probability of detection of threat submarines. The Navy has investigated and/or developed many technologies with the potential to meet its detection needs. These include both passive and active systems. According to the Navy, no one single technology will provide the solution during all tactical and environmental conditions. As stated in the Final EIS (page 2-2), LFA sonar “is an augmentation to the passive [SURTASS] detection system, and is planned for use when passive performance is inadequate.” While in some instances passive sonar can provide the detection required, under most conditions, passive sonar cannot detect quiet targets. Therefore, passive systems alone cannot meet the Navy's requirement to detect quiet, hard-to-find submarines during all conditions, particularly at long ranges.

Comment AC12:
What are the potential and specific conditions for exceeding 180 dB re: 1 micro Pa (root mean squared (rms)) beyond the 1-km (0.54-nm) mitigation zone? How does that relate to mitigation effectiveness?

Response:
Under almost all oceanographic conditions, the 180-dB SPL will not be beyond 1 km (0.54 nm) from the array. Even under ducted or CZ conditions, spherical spreading losses will dominate transmission losses within 1 km (0.54 nm). The actual 180 dB SPL will vary from 750 to 1,000 m (0.4-0.5 nm) from the array. This will not influence mitigation effectiveness.

Comment AC13:
In Comment 2-2.1 (in the Final EIS), the Navy states that “the restricted areas will not affect SURTASS LFA sonar routine training and testing, as well as the use of the system during military operations.”

However, on page 2-23 this is contradicted because the Navy stated that “Alternative 2 [unrestricted operations] would provide Fleet operators with * * * maximum submarine detection capability * * *.”

Response:
Training operations under Alternative 1 in the Navy's EIS will not provide for maximum submarine detection capabilities because of the geographic restrictions. However, Alternative 1 is the Navy's preferred alternative in order to protect marine mammals and as a result a small take authorization under the MMPA was not requested for Alternative 2, which would have a potential for increased marine mammal takes.

Comment AC14:
Why was the discussion of “Time Reversed Acoustics” as applied to LFA Sonar by NATO (North Atlantic Treaty Organization) and SACLANT (Supreme Allied Commander, Atlantic Center) research omitted from the Final EIS?

Response:
There was no discussion of time reversed acoustics in the Final EIS because: (1) No comments were received concerning this issue on the Draft EIS, and (2) It is not relevant to SURTASS LFA sonar analysis. The article referenced by the commenter is Fink (1999) (Scientific American 283(11): 91-97). The commenter stated, “This is an article about a Low Frequency Active Sonar application employed by NATO and the SACLANT research being done.” A review of the article found no reference to SURTASS LFA sonar. The NATO/SACLANT experiment concerned underwater communications.

Comment AC15:
Individual skippers, untrained in the effects of sound on wildlife, will be allowed to make their own instantaneous assessments based solely on military and political consideration, answerable to none.

Response:
NMFS disagrees. The U.S. Navy has asserted that it is committed to full compliance with the LOA issued by NMFS for taking marine mammals incidental to operating SURTASS LFA sonar. Under the LOA, shutdown criteria will be followed whenever a marine mammal is detected prior to entering the 180-dB SURTASS LFA mitigation zone.

Marine Mammal Impact Concerns (MMIC)

During the public comment period, several issues were raised that related more to interpretation of the MMPA than to a discussion of impacts on marine mammals. The former issues are addressed later in this document (see
MMPA Concerns
).

Selection of Species

Comment MMIC1:
The impacts on endangered, threatened and depleted species and stocks have not been properly assessed. Specifically mentioned were the migration paths of the female northern (Atlantic) right whale, dugong, and blue and fin whale concentrations in the open ocean.

Response:
NMFS believes that impacts to threatened, endangered and depleted species and stocks have been addressed and properly assessed in the Draft and Final EISs. In addition, the Navy has completed formal section 7 consultation under the Endangered Species Act (ESA) with NMFS with the issuance of a Biological Opinion. One result of that consultation is that the Spitzbergen stock of bowhead whales may be subject to Level B harassment. As a result, that stock has been added to the list of authorized species under these regulations.

Animals in unspecified migration corridors and open ocean concentrations are adequately protected by the tripartite mitigation protocols. Dugongs are discussed in RTC MMIC2.

Comment MMIC2:
Dugongs occur more than 12 nm (22.2 km) offshore in Australian waters. The U.S. Fish and Wildlife Service (USFWS) should be consulted.

Response:
Dugongs are usually found in calm, sheltered, nutrient-rich water less than 5-m (16.4 ft) deep, generally in bays, shallow island and reef areas which are protected against strong winds and heavy seas and which contain extensive sea grass beds. However, they are not confined to inshore waters. There have been sightings near reefs up to 80 km (43.2 nm) offshore in waters up to 37 m (121.4 ft) deep. The average minimum water depth that the SURTASS LFA vessel will operate is 200 m (656.2 ft). The shallowest depth that it can operate is 100 m (328 ft). As a result of sound attention in shallow and shoaling water, dugongs are unlikely to be affected.

The USFWS was consulted. On 18 May 1998, the Department of the Navy, pursuant to section 7 of the ESA, as amended, requested that the USFWS provide a compilation of listed, proposed, and candidate threatened and endangered species under the cognizance of the USFWS covering the ocean regimes in which SURTASS LFA sonar was intended to operate. A copy of this letter was provided in Appendix A of the Final EIS. In addition, the USFWS and the Department of the Interior were provided copies of both the Draft and Final EISs. Because of the offshore nature of SURTASS LFA sonar operations, the Navy determined that endangered or threatened species or the critical habitat of any protected species under the jurisdiction of the USFWS will not be affected.

Comment MMIC3:
Based on their marked avoidance responses (fleeing up to 80 km (43 nm) from an area where first disturbed) to relatively low levels of LF sounds between 94 and 105 dB (i.e., the 20-1000 Hz band) produced by icebreakers at extraordinarily long ranges, why were white whales (belugas) in Cook Inlet determined not to be affected by LFA sonar operating in the Gulf of Alaska?

Response:
This was discussed in the Final EIS (RTCs 3-2.10 and 3-2.11). The Cook Inlet beluga stock is located in coastal waters and, therefore, is not within the geographic region that SURTASS LFA sonar would operate. Cook Inlet beluga stocks are also unlikely to be subject to SURTASS LFA sonar signals considering the significant coastal sound attenuation prior to reaching Cook Inlet. This assumption has been verified through modeling, as depicted in Figure B-1 of Technical Report (TR) 2. This stock of belugas, therefore, was excluded from further analysis. More information is provided in the Final EIS Subchapter 3.2.5.1.

Furthermore, NMFS does not believe that the discussion on icebreaking vessel noise provided by the commenter is valid for SURTASS LFA sonar. First, NMFS believes the sounds affecting belugas at great distances were not in the 20-1,000 Hz range, but instead were in the 5-kHz range as cited by Richardson
et al.
(1995, p. 257) from the work by Cosens and Dueck (1993). Those latter authors expand on Richardson
et al.
(1995) by noting that belugas are relatively insensitive to sounds below 1 kHz, thus they are unable to detect LF ship noise beyond a few hundred meters of the source even though the source level is high (e.g., 501 Hz at 110 dB = 0.65 km). Higher frequency components of icebreaking vessel noise should be detectable at greater distances because the source levels are relatively high and detection thresholds (of belugas) at those frequencies are relatively low (Cosens and Dueck, 1993). Second, NMFS believes the commenter has taken Richardson
et al.
(1995) out of context. Richardson
et al.
(1995) did not state “fleeing up to 80 km from an area where first disturbed at levels between 94 and 105 dB.” The commenter has combined two separate discussions in Richardson
et al.
(1995). What Richardson
et al.
(1995) stated was that after initially being displaced by relatively low levels of noise from the approaching ship (94

to 105 dB in the 20 to 1000 Hz range), the whales sometimes returned 1 to 2 days later when the icebreaking noise levels were still as high as 120 dB. On page 257, Richardson
et al.
(1995) stated that belugas travel up to 80 km (43.2 nm) from the ship track, and typically remain away for 1 to 2 days. They also indicated that this may be due to the high frequency component. Also, this paragraph in Richardson
et al.
(1995) refers to both belugas and narwhals and references Finley
et al.
(1990) (which concerns both whale species). So, it's unclear whether Richardson
et al.
(1995) was referring to narwhals or belugas.

Concerning the belugas “fleeing,” on page 256 Richardson
et al.
(1995) stated, “Belugas are rather tolerant of the frequent passages by larger ship vessels traveling in consistent directions in summering areas such as the St. Lawrence River, Cook Inlet, and Beaufort Sea. * * * However, belugas often flee from fast and erratic moving small boats.” Icebreakers are not particularly fast, do not move erratically, and are not small. Also, as noted by Cosens and Dueck (1993), the environmental conditions in Lancaster Sound are likely very different than in other areas, such as Cook Inlet. Belugas in Lancaster Sound are inexperienced with shipping noises. Therefore, NMFS considers that the comparison provided by the commenter is not valid for SURTASS LFA sonar.

Comment MMIC4:
The EIS completely dismisses organisms that cannot hear in the LF range-humans or toothed whales and dolphins.

Response:
The Draft and Final EISs do not dismiss organisms that cannot hear in the LF range. In the Final EIS Subchapter 3.2.1, one of the criteria for analysis of potential impacts is that the organism must have organs or tissues with acoustic impedance different from water or be able to sense LF sound. Potential impacts to human divers and odontocetes are extensively discussed and analyzed. It should also be noted that humans and most odontocetes (which includes dolphins) are capable of hearing in the LF range.

Comment MMIC5:
NMFS dismissed concerns of one commenter that ice seals were excluded from consideration in the Draft EIS.

Response:
In response to the Marine Mammal Commission (MMC) comment on the Draft EIS, the hooded seal was included in the analysis in the Final EIS and the proposed rule. Also, see Final EIS (RTC 3-2.10).

Potential Effects

Comment MMIC6:
The Navy has dismissed behavioral effects below 180 dB as temporary and thus biologically insignificant.

Response:
The potential for significant changes in biologically important behavior is considered from 119 to 180 dB as discussed in the Final EIS Subchapter 4.2, specifically 4.2.3.2 and in TR 2.

Comment MMIC7:
Intense noise can cause strandings at a variety of frequencies and at RLs well below 180 dB; therefore, there is potential for strandings to occur from deployment of LFA. RLs lower than 180 dB re 1 micro Pa (RMS) can be extremely harmful, even lethal. The Grecian and Bahamian stranding events strongly suggest that SPLs far lower than 180 dB from mid-frequency and LF sounds could have lethal effects on several species of beaked whales over relatively large geographic areas. Therefore, the 1-km (0.54-nm) safety zone is inadequate.

Response:
While NMFS agrees that intensive sounds could result in strandings at various frequencies for those marine mammals whose hearing includes the primary frequencies of the sound source, NMFS does not agree with the statements that strandings would occur at levels significantly less than 180 dB. First, results of the Low Frequency Sound Scientific Research Program (LFS SRP) indicated no significant change in biologically important behavior for exposure to sound levels up to 155 dB; i
.e.
, there were no behavioral reactions indicating that marine mammals were being significantly affected or injured. Even though there is an increased probability of behavioral harassment from 155 to 180 dB, there is no indication that behavioral harassment impacts could cause strandings. It should also be noted that many whales vocalize in this range and are not known to result in strandings. With regard to the potential for injury below 180 dB from possible resonance effects, Cudahy and Ellison (2002) noted that “each of the
in vivo
(in the living body) and theoretical studies related to potential tissue damage from underwater sound support a damage threshold on the order of 180 to 190 dB.” This tissue damage could include lung damage and hemorrhaging. Also, it has been hypothesized that LF sound could cause bubble growth from supersaturated gases in the blood (similar to the human diver condition known as the bends). Crum and Mao (1996) stated that received level 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 (See Final EIS, page 10-137).

Moreover, the Navy's monitoring and mitigation protocols proposed for employment of SURTASS LFA sonar will preclude employment in narrow and deep channels surrounded by land such as those in the Bahamas (22-km/12-nm restriction); and the shut-down criteria for the Navy's high-frequency marine mammal monitoring (HF/M3) sonar has been expanded to include any detection by the HF/M3 sonar that is classified as a marine mammal, which could occur up to 1 km beyond the SURTASS LFA sonar mitigation zone. The stranding of Cuvier's beaked whales in the Mediterranean in 1996 was considered in the SURTASS LFA sonar impact analysis. For details, see the Final EIS pages 3.2-45 to 3.2-47. Both the Greek and Bahamas strandings involved beaked whales. These species are mid-frequency specialists. The only common acoustic source to both events was in the mid-frequency range.

For discussion on whether or not the 1-km (0.54 nm) safety zone is adequate, please see Mitigation Concerns later in this document.

Comment MMIC8:
The assumption that temporary threshold shift (TTS), even when it lasts for days, does not constitute injury is intrinsically flawed. TTS may lead to increased vulnerability to predation or to confusion, which may lead to stranding and death.

Response:
TTS is a change in the threshold of hearing (the quietest sound an animal can hear), which could temporarily affect an animal's ability to hear calls, echolocation sounds, and other ambient sounds. As such, it could result in a temporary disruption of behavioral patterns, thereby resulting in Level B harassment under the MMPA. The best research to date indicates that the distortion and dysfunction of sensory tissue observed during TTS are only temporary and fully reversed upon recovery (
i.e.
, occasional TTS produces no permanent tissue damage to the ear, only the temporary nondestructive impairment of tissue that fully recovers). This type of temporary nondestructive impairment, as well as the use of TTS in human damage risk criteria, is the scientific basis for not considering TTS as an injury.

Acousticians are in general agreement that a temporary shift in hearing threshold of up to 40 dB due to moderate exposure times is fully recoverable and does not involve tissue damage or cell loss. Liberman and Dodds (1987) state, “* * *acute threshold shifts as large as 60 dB are routinely seen in ears in which the

surface morphology of the stereocilia is perfectly normal.” Stereocilia are the sensory cells responsible for the sensation of hearing. In the chinchilla, no cases of TTS involve the loss of stereocilia, but all cases of PTS do (Ahroon
et al.
, 1996). Cell death clearly qualifies as Level A harassment (injury) under the MMPA. Because there is no cell death with modest (up to 40 dB) TTS, such losses of sensitivity constitute a temporary impairment but not an injury. Since the boundary line between TTS and PTS is not clear, definitive, and predictable for marine mammals, NMFS has adopted the standard that 20 dB of TTS defines the onset of PTS (
i.e.
, a temporary shift of 20 dB in hearing threshold). This intentionally conservative standard is appropriate because all of the research on stereocilia has been done on terrestrial mammals, which may be poor models for marine mammals since marine mammals have evolved to withstand large pressure change differentials during diving. This should not be interpreted to mean that the onset of PTS results from adding 20 dB to the dB level found to cause the onset of TTS in an animal, but instead means that the onset of PTS is the sound exposure in level (dB) and duration that would cause a temporary shift of 20 dB in hearing threshold.

As stated in previous actions (66 FR 22450, May 4, 2001), second level impacts (such as potential predation) due to a marine mammal having a temporary hearing impairment cannot be predicted and are, therefore, speculative and difficult to quantify. In fact, any disruption of behavior (Level B harassment) could, with suppositions, be seen as potentially dangerous and, therefore, considered potentially injurious (Level A harassment) as well. Similarly, all injuries could be seen as being accompanied by some disruption of behavior and therefore, Level B disturbances as well as Level A injuries. Such reasoning blurs the distinctions that the statutory definitions of harassment attempt to make.

NMFS believes that Level B harassment, if of sufficient degree and duration, can be very serious and requires consideration when making impact determinations. For example, moderate TTS does not necessarily mean that the animal cannot hear, only that its threshold of hearing is raised above its normal level. The extent of time that this impairment remains is dependent upon the amount of initial TS, which in turn depends on the strength of the received sound and whether the TTS is in a frequency range that the animal depends on for receiving cues that would benefit survival. It should be noted that increased ambient noise levels, due to biologics, storms, shipping, and tectonic events, may also result in short-term decreases in an animal's ability to hear as well as normal. For example, ambient noise in the Hawaiian Islands Humpback Whale National Marine Sanctuary increases seasonally in conjunction with an increase in humpback whale abundance, with no known impacts to these animals. NMFS scientists believe that marine mammals have likely adopted behavioral responses, such as decreased spatial separation, slower swimming speeds, and interruption of socialization to compensate for increased ambient noise or hearing threshold levels.

A hypothesis that marine mammals would be subject to increased predation presumes that the predators would either not be similarly affected by the resultant SPL or would travel from areas outside the impact zone, indicating recognition between a sonar signal at some distance and potentially debilitated food sources. Moreover, NMFS notes that TTS does not cause confusion or disorientation. Disorientation is caused by vestibular affects to the inner ear, not related to TTS (although an animal having vestibular effects could also suffer from TTS). For example, humans attending certain sport or music events may incur a TTS impairment due to the noise, but are not noted for being disoriented afterwards, unless caused by something other than noise. Therefore, NMFS does not believe the evidence warrants that TTS be considered as an injury.

However, because of the SURTASS LFA sonar mitigation zone and the use of the HF/M3 sonar to locate mammals prior to incurring potential injury, the number of animals that might experience an injury from SURTASS LFA transmissions is considered to be few to none. Therefore, no expected increased vulnerability to predation or confusion by SURTASS LFA sonar is expected. This issue will be discussed later in this document (see RTC MMIC40).

Comment MMIC9:
There is no evidence that TTS should not occur at SPL of below 180 dB. Caution should be used in citing studies (such as Schlundt
et al.
, 2000) where captive animals were used and the subject animals were not considered to be at the highest risk from LF sound.

Response:
The two species tested in Schlundt
et al.
(2000), were tested at their best hearing frequencies (i.e., mid-frequency). In fact, neither the tested bottlenose dolphins nor the belugas exhibited TTS after a 1-second exposure to maximum levels of 193 dB at 0.4 kHz (400 Hz), the approximate frequency range of SURTASS LFA sonar. NMFS agrees, however, that TTS may occur below 180 dB, depending in part on the duration of the signal and the frequency sensitivity of the recipient. Schlundt
et al.
(2000) showed that bottlenose dolphins experience onset of masked TTS (defined as 6 dB of shift) from a one-second, 3 to 75 kHz, exposure at approximately 192 dB RL sound. Assuming a 3-dB exchange rate (e.g., the same amount of shift would result from reducing the intensity by 3 dB and doubling the exposure time (Finneran
et al.,
2000)), these odontocetes could experience TTS (Level B harassment) from a 16-second exposure to a 180-dB sound at their best frequency, a 32-second exposure at 177 dB, and a 100-sec. exposure at 173 dB. Since this approximation is for mid-frequency marine mammal specialists at mid-frequency sound levels, NMFS believes it is probable that LF marine mammal specialists would incur TTS (Level B harassment) at similar levels and duration to LF sounds. However, the typical SURTASS LFA signal is not a constant tone, but rather a transmission of various waveforms that vary in frequency and duration. A complete sequence of sound transmissions last between 6 and 100 seconds, although the duration of each continuous frequency sound transmission is never longer than 10 seconds. Therefore, the SURTASS LFA signal itself, while possibly capable of causing TTS (Level B harassment), is unlikely to result in Level A harassment (injury) in marine mammals at levels below 180 dB.

Comment MMIC10:
Why does NMFS focus on “serious injury”, assumed as PTS, whereas the MMC and many other experts have declared that behavioral impacts of biological significance to reproduction and survival cannot be ruled out as results of exposure to LFA well below 180-dB RL? According to NMFS, these impacts cannot be observed over the short term, cannot be mitigated, cannot be quantified as reliable data, and cannot be considered without delaying deployment of LFA. NMFS excludes “behavioral modifications” biologically significant to reproduction and survival because they cannot be observed.

Response:
NMFS and the Navy concur that behavioral impacts of biological significance can occur at SPLs below 180 dB. This is implicit in the calculations for Level B takings conducted using the Acoustic Integration Model (AIM). For Level B incidental harassment takings, NMFS

will determine whether takings by harassment are occurring based on whether there is a significant behavioral change in a biologically important activity, such as feeding, breeding, migration or sheltering. All of these activities are potentially important for reproductive success of a marine mammal population.

However, NMFS and the Navy focus on reducing the level of incidental take by injury, through appropriate mitigation measures (discussed elsewhere in this document), because it believes that injury and mortality can be reduced to the lowest level practicable through various monitoring and mitigation means. In addition, extensive AIM modeling aggregate data results versus probability of risk for all marine mammals modeled at 32 sites worldwide illustrated that the preponderance of all modeled received levels were below 155 dB. This is in the range of exposures in the LFS SRP during which no behavioral impacts of biological significance were observed. Moreover, as detailed elsewhere in this document, NMFS will work with the Navy to undertake a research program to validate impacts on marine mammals and the estimated harassment takes in the area outside the 180-dB isopleth (see RTC MOC25).

Comment MMIC11:
Just because animals remain in a particular environment with anthropogenic noise sources present does not mean that they are not negatively impacted by it. They may tolerate the interfering and/or fatiguing effects of the noise because it is occurring in an area of particular biological significance.

Response:
NMFS and the Navy agree that animals exposed to SURTASS LFA sonar signals may continue feeding. Phase I of the LFS SRP demonstrated this for blue and fin whales. Also, California sea lions (at Ballard Locks, Seattle, WA) and seals approaching aquaculture pens that are equipped with acoustic harassment devices will feed even in the presence of intense sound sources. However, the 180-dB safety zone for SURTASS LFA sonar insures that no animals will be exposed above that level regardless of context. The 180-dB limit is conservative because both blue and fin whales are known to produce vocalizations at 186 dB. That is, the SURTASS LFA criterion affords animals protection from SPLs that they may commonly experience from other animals.

The alternative hypothesis is discussed in RTC 4-5.39 of the Final EIS.

Comment MMIC12:
The LOA application and the Final EIS state, “Even with a 25 percent reduction in foraging efficiency for all of the 20 days, this would represent only a 5 percent reduction in food intake for that season.” The commenter believes that a reduction of 5 percent might affect breeding success, or survival.

Response:
Based on the natural regional and annual variability in chlorophyll concentrations that indicate food production for many marine mammals, particularly the baleen whales, a 5 percent change in food availability falls within very reasonable statistical bounds. While this does not necessarily mean that an animal would not change its foraging range in order to make up for a food deficiency in one area, it does point up the high probability that from year-to-year, marine mammals can be expected to have different levels of food intake. Thus, a one-time 5 percent change in food intake for a single season (provided the animal is not affected in more than that single season) is considered to have a very low probability of exerting any significant change in that animal's survival or breeding success; and certainly will not affect an animal stock in any significant way.

Comment MMIC13:
No research done on effects of marine mammals feeding, or the species upon which they feed.

Response:
The LFS SRP conducted research related to marine mammal feeding. The goal of the LFS SRP was to demonstrate avoidance reactions for LF-sensitive species (baleen whales) during critical biological behaviors (foraging/feeding, migrating, breeding). Phase I of the LFS SRP conducted manipulative field experiments to test the effects of LF sound on foraging fin and blue whales off San Nicolas Island, CA. For additional information see Croll
et al.
(2001) and TR 1.

In addition, the potential effects of SURTASS LFA sonar on fish and prey species are covered in the Final EIS Subchapters 4.1.1 and 4.2.7.6. The potential effects on invertebrates are covered in the Final EIS Subchapter 3.2.1.1.

Non-Auditory Metrics

Comment MMIC14:
It is incorrect to pick sensory modality for the only discussion concerning the potential harm to marine mammals from mid- and low-frequency sonar. To support this, Richardson
et al.
(1995) was paraphrased in a misleading way because the authors listed four zones of noise influence in which the fourth and most extreme was the zone of hearing loss, discomfort, or injury that is in the “area near the noise source * * *.” In other words, NMFS has inappropriately attempted to lead the discussion toward auditory effects, whereas the authors cited, and objective reviewers clearly recognize, that there are many non-auditory traumas attributable to sound received at high levels. Those listed by the commenter included lung damage and organ system hemorrhage, vestibular dysfunction, and bubble growth in tissue.

Response:
NMFS does not agree that it has paraphrased Richardson
et al.
(1995) incorrectly. While Richardson
et al.
(1995) listed only four types of noise influence, in recent years, NMFS has defined six categories of noise based on Richardson
et al.
(1995), but updated by Richardson in several small take applications (see for example, BPXA, 1999; Western Geophysical, 1999, 2000; WesternGeco, 2001). This updated information was incorporated into the preamble to the proposed rule. Recently, NMFS has updated small take notices with recognition that there is a potential for non-auditory impacts from loud noises. For example, in the preamble to the final rule for NPAL (66 FR 43442, August 17, 2001) NMFS noted that “intense acoustic or explosive events 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.” This statement has been added into the current document in recognition of the potential for non-auditory impacts from loud noise events.

However, what is relevant in this document and in the Final EIS is whether or not marine mammals will be exposed to SURTASS LFA signals at high enough intensities to cause non-auditory traumas. With the proposed mitigation measures, the Final EIS analysis concluded that the potential impact on any stock of marine mammals from injury is considered negligible, and the effect on the stock of any marine mammal from significant change in a biologically important behavior is considered minimal. These potential effects include non-auditory traumas (tissue damage), which are considered to be injuries.

Since the release of the Final EIS, an investigation by Cudahy and Ellison (2002) noted that the expected threshold for
in vivo
(in the living body) tissue damage (including lung damage and hemorrhaging) for LF sound is on the order of 180 to 190 dB. Vestibular effects themselves, which could affect balance and equilibrium, while not considered to be an injury, could be a manifestation of an injury when caused by an impact such as PTS. However, these effects are based on humans.

Vestibular function was investigated by the Navy during the Diver's Study and the results reported in TR 3. Measurable performance decrements in vestibular function were observed for guinea pigs using 160 dB SPL signals at lung resonance and 190 dB SPL signals at 500 Hz. It should be kept in mind that guinea pigs are not aquatic species and, as such, are not as robust to pressure changes as marine mammals. Finally, as stated in Crum and Mao (1996) and as discussed in the Final EIS (page 10-137), researchers hypothesized that the received level 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. Because the above “non-auditory traumas” are not expected to result from sound exposure below SPLs of 180-dB and the high detection rate of the HF/M3 sonar assuring required SURTASS LFA sonar shutdown when any marine mammal approaches or enters the 180-dB SURTASS LFA mitigation zone, the risks of these traumas to a marine mammal approach zero.

Comment MMIC15:
The Navy and NMFS have systematically underestimated the number of animals that may be taken by SURTASS LFA sonar, if deployed, because: (1) Neither the Navy nor NMFS has considered the potential for non-auditory physiological impacts; (2) neither has meaningfully evaluated the potential for stranding; (3) both have underestimated the potential for auditory impacts; (4) both have failed to consider the full range of behavioral impacts and have underestimated the potential for those it has considered; (5) neither has accounted for cumulative and synergistic impacts of multiple active systems or other sound sources operating in the same region; and (6) both have underestimated or have failed to assess impacts on prey species.

Response:
The number of animals potentially taken has not been underestimated. On the contrary, the analysis contained in the Draft and Final EISs has erred on the side of caution. The analysis is based on criteria for impacts based on the potential effects to baleen whales, which are considered the most sensitive marine mammals to LF sound (Ketten, 2001). These potential effects are then applied equally to all marine mammals that, based on geographic demographics, could be exposed to the SURTASS LFA sonar signal. Most of these animals are not as sensitive to LF sound as the baleen whales. Some may be nearly as sensitive, such as the sperm whale and elephant seal; but more are predominately sensitive to mid- to high-frequency sounds. Other conservative assumptions used in the analysis are presented in the Final EIS Subchapter 1.4.3. Responses to the specific issues are provided here in summary and in detail later in this document:

Non-auditory physiological impacts:
As mentioned in RTC MMIC20, Cudahy and Ellison (2002) stated that the expected threshold for
in vivo
tissue damage for low frequency sound is on the order of 180 to 190 dB.

Stranding:
This issue is addressed in detail starting with RTC MMIC22 in this document. In addition, a review of all SURTASS LFA operations with recorded stranding events determined that there have been no strandings associated with SURTASS LFA sonar.

Auditory impacts:
The potential for auditory impacts as discussed in the Draft and Final EISs is based on scientific research and conservative analyses.

Behavioral impacts:
The criteria for the potential risk of significant change in biologically important behavior, which are discussed in detail in the Draft and Final EISs, are based on scientific research and conservative analyses. See RTC MMIC10 and MMPAC22a in this document.

Cumulative impacts:
Cumulative impacts are covered in the Final EIS in Subchapter 4.4. The synergistic impact of multiple active systems is analyzed in the Final EIS Subchapter 4.2.7.4. In addition, SURTASS LFA sonar operations will usually avoid areas with high levels of LF noise/sound (
e.g.,
seismic surveys).

Prey species:
Prey species are discussed in the Final EIS. Many of these species, such as squid and zooplankton, are not analyzed because they did not meet the screening criteria used in the Draft and Final EISs for determining whether species would be impacted as determined in Croll
et al.
(1999). Fish species are covered in the Final EIS Subchapters 3.2.2 and 4.1.1. Additionally, during the LFS SRP Phase I, prey field studies were conducted. Variations in these fields were within the normal prey field variations expected from typical changes in natural oceanographic conditions (see TR 1 for more information).

Therefore, based on the above information, NMFS concludes that the potential takes of marine mammals from the operation of the SURTASS LFA sonar has more likely been overestimated by the Navy than underestimated.

Comment MMIC16:
One commenter notes that the LOA application states, “* * * a marine mammal would have to receive one ping greater than or equal to 180 dB or many pings at a slightly lower RL to possibly incur non-serious injury.” This, the commenter believes, is inconsistent with discussions elsewhere in the LOA application and the Final EIS and proposed rule. According to those discussions, “all marine mammals who receive a ping greater than 180 dB are presumed to be injured (that is, seriously injured).” This is presented as conservative because the mitigation seeks to exclude all marine mammals from the 1 km (0.54 nm) “serious injury impact zone (corresponding to the 180 dB sound field).” Therefore, marine mammals will definitely incur serious injury, as a “conservative” assumption. Clarify “serious injury” well inside of the 180-dB zone and any animal within the 180-dB zone is considered to be injured. The possibility of damage should be at 1 km (0.54 nm), not next to the array.

Response:
Neither the proposed rule nor the Final EIS use the term “serious” injury when referring to the 180-dB criterion. In response to comment 18 in the proposed rule, NMFS stated that for this proposed action, scientists have determined that a single-ping RL of 180 dB can be considered a scientifically precautionary level to prevent the potential onset of injury to marine mammals. Serious injury is discussed in response to comment 20 in the proposed rule. NMFS stated that because serious injury is unlikely to occur unless a marine mammal is well inside of the 180-dB safety zone and close to the SURTASS LFA sonar source, and because the closer a marine mammal is to the SURTASS LFA source the more likely it is to be detected and transmissions suspended, the potential for serious injury is minimal.

The LOA application was based on the Draft EIS while the proposed rule was based on the Final EIS. For this reason the LOA application is inconsistent with the Final EIS and proposed rule because the terms “non-serious” and “serious” injury were changed from the Draft EIS to the Final EIS as a result of comments received on the Draft EIS. Also see response to comment 11 in the proposed rule document.

Comment MMIC17:
Many scientists believe that LFA sonar is likely to be more harmful than mid-frequency sonar because it covers greater distances and, therefore, exposes more animals and has longer pings.

Response:
Comparisons of mid- and low-frequency sonar characteristics do not support this belief. It is true that LF-sonar signals travel farther and usually have longer pulse/ping lengths than MF-sonar signals, under most oceanographic

conditions, which is why the Navy developed the technology. Of importance, however, is the animals' physical susceptibility and behavioral reaction to LF sounds, and that there are far greater numbers of marine mammals sensitive (
i.e.,
auditory—how well they hear) to mid- and high-frequency sound than to LF sound. Most marine mammals hear, vocalize and/or echolocate in the mid- to high-frequency range. In addition, over the past 5 years, the potential effects of LF sonar on marine life has been studied in greater detail than for mid-frequency sonars, meaning there have been more data generated to support the conclusions presented in the Final EIS. NMFS believes that the SURTASS LFA process could be a model of the precautionary approach to introducing novel sound sources into the sea, moving incrementally, conducting research, and developing appropriate mitigation measures.

Comment MMIC18:
Because LFA signals are best propagated in the deep sound channel, distant whales are likely to hear the source.

Response:
That is a correct statement provided the whales are actually in the deep sound channel and that there is a sufficient amount of SURTASS LFA sonar energy within the channel for the whales to hear. Also, as discussed later in this document, simply hearing the SURTASS LFA signal does not necessarily indicate that a whale has been harassed or “taken.”

Comment MMIC19:
Injury and psychological effects can result in stranding or adverse reaction, such as rapid ascent from depth.

Response:
The Final EIS offers detailed analysis and discussion to support the conclusion that, given the employment of SURTASS LFA sonar will occur as proposed in the Final EIS (with geographic restrictions and monitoring/mitigation measures), the potential for injury to any marine mammals is considered negligible. See Subchapter 1.4 and Subchapter 4.2 for more details. Also, despite the fact that the measurement of the potential for psychological effects on marine mammals from underwater sound sources in the field is extremely problematic and expensive to collect, it is not unreasonable to consider that the analysis of the potential for behavioral effects can be used as a benchmark. Thus, the Final EIS concludes that if SURTASS LFA sonar is employed with the proposed geographic restrictions and monitoring/mitigation measures, the effect on the stock of any marine mammal from significant change in a biologically important behavior is considered minimal.

Finally, it seems plausible that marine mammals that have evolved in an ambient hydrostatic pressure environment spanning several orders of magnitude (1:10
3
) of dynamic range would be predisposed to have an innately more rugged physiology for handling pressure changes than terrestrial animals (Cudahy and Ellison, 2002). Therefore, no psychological or physiological effects would be anticipated from any rapid ascent from depth.

As mentioned in RTC MMIC15 and later in RTC MMIC27, a review of all SURTASS LFA sonar operations has determined that there have been no strandings associated with SURTASS LFA sonar or any other sonar operating below 450 Hz.

Comment MMIC20:
LF sonar disrupts the immune system, nervous system, and other body systems and tissues, and causes psychological problems.

Response:
See previous response regarding psychological effects. Also, there is no reason to suspect that an intermittent noise source, such as SURTASS LFA sonar would have impacts on marine mammal immune, nervous or other body systems. If LF sounds were to have system-level impacts, one would presume that such effects would manifest first in those marine mammals inhabiting noisy areas, such as offshore large ports where large vessels (with LF sounds) occur in large numbers, or the Gulf of Mexico, off Newfoundland or in the North Sea where offshore oil and gas seismic activity predominate almost year-round.

Regarding tissue effects, Cudahy and Ellison (2002) indicate that the potential for
in vivo
tissue damage to marine mammals from exposure to underwater LF sound will occur at a damage threshold on the order of 180 to 190 dB. This includes: (1) Transluminal (hydraulic) damage to tissues at intensities on the order of 190 dB or greater; (2) vascular damage thresholds from cavitation at intensities in the 240-dB regime; (3) tissue shear damage at intensities on the order of 190 dB or greater; and (4) tissue damage in air-filled spaces at intensities above 180 dB.

Therefore, unless an animal is within the 180-dB SURTASS LFA sonar mitigation zone, NMFS believes that present scientific information indicates that there should be no physical damage to marine mammal body systems or tissues at an SPL less than 180 dB. Because of the mitigation measures, the potential taking of a marine mammal within the 180-dB mitigation zone is considered minimal. For additional information see Final EIS (RTC 3-2.2, 4-5.14, and 4-6.21).

Comment MMIC21:
Injury and aversion could extend to at least the first CZ (33 to 65 km (17.8 to 35.1 nm)).

Response:
For discussion on CZs, refer to the discussion earlier in this document (see
Description of Acoustic Propagation
). As discussed in response to earlier comments, unless an animal is within the 180-dB SURTASS LFA sonar mitigation zone, the best scientific information available to NMFS indicates that there should be no physical damage (or injury) to marine mammal body systems or tissues at SPLs below 180 dB. Because the first CZ (as shown in Figure 1) is well beyond the 1-km (0.54 nm) radius of the 180-dB SURTASS LFA mitigation zone, no injury should occur at the first CZ or beyond.

The Navy concluded in the Final EIS analysis that significant changes in biologically important behaviors, which could include aversion, may occur, although effects to marine mammal stocks are considered to be negligible.

Strandings

Comment MMIC22:
Because none of the previously identified beaked whales in the Bahamas have been seen since the stranding, they may have all been killed or displaced.

Response:
Worldwide, the numbers and behavior of beaked whales are poorly known because the animals tend to be shy and avoid survey vessels. The beaked whale population of the Northeast and Northwest Providence Channels of the Bahamas is known somewhat better than in the rest of the Caribbean because resident biologists have been studying it for some time. While one of these biologists stated that the animals are no longer in the area of the March 2000 stranding event, and NMFS has no reason to doubt this statement, the statement that these whales all died from the sonar is an assertion that is not based on data. These whales could have moved to a different foraging area. Without data, one cannot fairly attribute disappearances to any particular cause. These data would not be difficult to obtain. However, one cannot presume that because one type of sonar is implicated in taking one type of whale, another sonar system will have a similar effect. Therefore, the above comment is noted as a comment ancillary to the action under consideration here.

Comment MMIC23:
The Navy stated that because of the offshore nature of SURTASS LFA sonar operations, it does not believe that there is a potential for LFA sonar to result in marine mammal stranding incidents. Is this because the

operations are a long distance from coastlines (and strandings are unlikely to come ashore), or because the LFA sonar will not cause strandings?

Response:
NMFS does not consider strandings to occur only when an animal comes ashore. Any marine mammal injured, dead, or dying comes under the NMFS stranding program and is investigated to the fullest extent possible. However, based on the operational parameters of the SURTASS LFA sonar, there is no reason to believe that there is a potential for the SURTASS LFA sonar to cause injuries or strandings. In addition, because of the fact that SURTASS LFA sonar operations will not occur closer than 12 nm (22 km) from any coastline and because the mitigation measures (passive acoustic, visual observations, and a new high frequency sonar designated HF/M3) used will be above 95 percent effective in detecting most marine mammals prior to entry into the 180-dB SURTASS LFA sonar mitigation zone, injury and/or strandings are highly unlikely.

Comment MMIC24a:
Active sonar can kill/traumatize whales. Examples are strandings (Greece, Bahamas, 6 additional strandings, etc.). LFA sonar will cause the extinction of beaked whales and the entire world population of marine mammals. The Navy has ignored a number of mass strandings connected with naval maneuvers involving one form or another of active sonar. Discuss the well-documented stranding of four beaked whales on 3 different Caribbean islands on October 1999, which were correlated with loud sounds in the water. The Canadian LFA system (Towed Integrated Active-Passive Sonar (TIAPS)) has been implicated in the stranding of three Blainville's beaked whales in March 1998 at Rum Cay in the Bahamas. The NATO LFA system (Towed Vertically Directive Source (TVDS)) has been implicated in at least two stranding events in the Mediterranean: (1) Thirteen mammals in Kyparissiakos Gulf in Greece on May 12 and 13, 1996 and (2) nine mammals in the western Peloponnesus approaches on October 1997. These strandings demonstrate that whales can be injured by LF sonar. Why was there a failure to consider the strandings that followed NATO use of low-frequency sonar in the Mediterranean in 1996?

Response:
Sonars differ in their operating characteristics, and marine mammal species differ greatly in the sounds to which they are susceptible. This is often overlooked by the public. The scientific investigation regarding the Bahamian beaked whale stranding found that the tactical mid-range frequency sonars that were in use aboard U.S. Navy and allied ships during the March 15-16, 2000, Bahamas sonar exercise were the most plausible source of acoustic or impulse trauma to six beaked whales (DOC and SECNAV, 2001). Tissues from these animals are being intensively studied for the mechanism that caused death. DOC and SECNAV (2001) noted, “SURTASS LFA, another Navy sonar, had no involvement in this event.”

A review of the Smithsonian stranding database shows that there have been seven other instances of beaked whale strandings involving more than one species. One of these activities involved ordnance, two were not identified with military activities, and four were concurrent with military maneuvers (Potter, 2000). Except for the Bahamas stranding, no tissues were collected, and the type of military maneuvers and time and distance separating them from the strandings are not known. Without this information science can never prove whether sonar did or did not cause these deaths. These events point out the pressing need for proper scientific study of marine mammals around many sonar operations, including those of SURTASS LFA sonar.

Investigations indicate that SURTASS LFA sonar has not been known to cause a stranding; and because it uses extensive mitigation measures (passive acoustic, visual observers, and the HF/M3 sonar) that make an injury and therefore a stranding unlikely. No mitigation was used with any of the other events just discussed.

The stranding of Cuvier's beaked whales in the Mediterranean in 1996 was considered in the SURTASS LFA sonar impact analysis. For details, see the Final EIS pages 3.2-45 to 3.2-47.

On October 3, 1999, 4 beaked whales (
Ziphius cavirostris
) stranded in the U.S. Virgin Islands. The Navy had exercises ongoing in the offshore waters and also had live-fire exercises in nearshore waters during the time period when the beaked whales stranded. The offshore exercises, but not inshore exercises involved sonar. Although SURTASS LFA sonar was not involved in these exercises, the Navy has not formally confirmed whether mid-frequency sonars may have caused these four whales to strand in the Caribbean.

Information on the stranding in March 1998 at Rum Cay is provided in the following RTC.

Comment MMIC24b:
One commenter stated that TIAPS, the Canadian LFA system, has been implicated in the stranding of three Blainville's beaked whales in March 1998 at Rum Cay in the Bahamas. He also stated that a large balaenopterid (cf.
Balaenoptera physalus
) stranded alive under mysterious circumstances on Eleuthera Island in the Bahamas on March 3, 2000, following a TIAPS exercise in the area on February 2000.

Response:
TIAPS is an independent Research and Development project being conducted by the Defense Research and Development Canada, an agency of the Department of National Defense and there is no frequency overlap between TIAPS and SURTASS LFA sonar (TIAPS is approximately 1 kHz). To respond to this comment, the Navy contacted the Project Manager/TIAPS at the Canadian Defense Research Establishment Atlantic. The project manager stated that he cooperated with the commenter and his associates in regard to his investigation of both strandings. Concerning the three beaked whale strandings in March 1998 it is apparent that TIAPS Q244 was completed in Exuma Sound well before the time the whales stranded. NMFS, of course, is interested in receiving any information regarding this stranding for its stranding database.

In regard to the March 2000 stranding of a fin whale, because that stranding occurred 18 days after the TIAPS exercise, there does not appear to be a connection between TIAPS trials and the March 2000 strandings in the Bahamas.

Comment MMIC25:
Historical records of beaked whale strandings, compiled by the Smithsonian Institution's Marine Mammal Program in the wake of the Bahamas event, suggest a very high correlation between naval activities and both individual beaked whale strandings and multi-species strandings involving beaked whales. The correlation of all the known mixed species mass strandings involving beaked whales with nearby naval maneuvers (International Whaling Commission (IWC, 2001)) most certainly provides evidence for causation. Further investigations by the Navy into military activities and cetacean stranding is warranted.

Response:
As mentioned in RTC MMIC24a, Potter (2000) indicates that there have been seven mixed species mass strandings involving beaked whales. Although four of the seven mixed-species mass strandings are associated in time with some type of military maneuvers, none appears to be related to LF sonar.

Simmonds and Lopez-Jurado (1991) stated that between 1982 and 1989 there were 22 strandings of cetaceans in the Canary Islands, with only three being

related in time to military activity. Simmonds and Lopez-Jurado (1991) reported in their text that “Local people have only been aware of such military maneuvers three times since 1985; on each occasion mass live strandings have occurred.” These authors indicate that military maneuvers were documented in 1985, 1988 and 1989. However, they report a mass stranding in the Canary Islands in 1986, and there is no mention of military activity in either their report or the Smithsonian database. Furthermore, there is another mixed species mass stranding involving beaked whales noted in the Smithsonian database that occurred in the Canary Islands in 1987, which is also not associated with military activity. One of the mass strandings, from 1974, had an animal with bullet holes found in the body.

Only one of these seven multiple species strandings is known to have occurred concurrent with naval activities and the use of active mid-frequency sonar, the Bahamas stranding in March 2000. There was a single species, mass stranding of Cuvier's beaked whales in the Kyparissiakos Gulf in Greece concurrent with the testing of a NATO sonar, whose lowest frequency is 450 Hz, but which also transmits in the 2.6 kHz to 3.4 kHz range. See the Final EIS Subchapter 3.2.5.1 for a more information on these beaked whale strandings.

Summarizing, the information available on marine mammal strandings is, at best, incomplete and inconsistent. Since NMFS does not know how many sonar operations occurred during this time period without marine mammal injuries or strandings, it believes that the data do not necessarily suggest a high correlation between naval activities and beaked whale strandings, nor do they provide evidence of causation; especially for LF sonar.

However, NMFS has not dismissed this information and will coordinate information contained in the annual LOA report, principally time and location of every SURTASS LFA sonar operation, with stranding data that NMFS receives from its stranding coordinators in order to determine whether any links might exist between them.

Comment MMIC26:
Based on calculations of the probability of the number of coincidences between strandings and military activities, under the null hypothesis, it is very unlikely that the stranding events of beaked whales were unrelated to military operations unless military operations are very common.

Response:
The commenter's application of a binomial probability experiment methodology to these data may not be statistically appropriate. NMFS notes that the “rate” of military activity is undefined and unquantified. Also, the stranding data are most probably skewed, in that the distribution of stranding network effort, and naval activity are both non-random and are most likely correlated, since generally countries with an advanced economy and military can afford stranding network efforts and attract military attention.

Comment MMIC27:
Because Dr. Tyack's analysis discussed in Final EIS (RTC 4-4.21) is not presented in detail, the response is “arbitrary and capricious.” Provide a comparison of Dr. Tyack's analysis to that of Dr. Whitehead in his May 4, 2001, comments on the proposed rule. One commenter disputes the NMFS statement that “there is no evidence linking SURTASS LFA sonar transmissions to any stranding events * * *” because of the beaked whale stranding on the Grecian coast in 1996.

Response:
The Grecian stranding in 1996 was not caused by SURTASS LFA sonar because that sonar was not operating in that area. Both the Greek and Bahamas strandings involved beaked whales. These species are mid-frequency specialists. The only common acoustic source to both events was in the mid-frequency range. There were no low frequency sonar sources involved in the Bahamas stranding (DOC and SECNAV, 2001). Therefore, the evidence does not support the LF component as having a causal relationship to the stranding of beaked whales in Greece. Because tissue damage is not expected to occur from sound exposure below SPLs of 180 dB (Cudahy and Ellison, 2002) and the SURTASS LFA sonar operational protocols require shutdown when any marine mammal approaches and before entering the safety (LFA sonar mitigation) zone, the risk of injury to a marine mammal is negligible. It should be noted that there were no mitigation protocols during either the 1996 or 2000 naval operations, although NMFS understands that the Navy has instituted mitigation measures since the March 2000 event to avoid future stranding incidents (DOC and SECNAV, 2001).

Dr. Peter Tyack of the Woods Hole Oceanographic Institution (Woods Hole) attempted to conduct a correlation analysis of marine mammal strandings and past SURTASS LFA sonar operations. There was no evidence of any correlation; thus, no report was generated. The latter analysis in the comment was discussed in the previous RTC in this document.

Comment MMIC28:
There is now a weight of evidence (Bahamas stranding event) that beaked whales are at far greater risk from these operations (naval sonar operations) than the four species of mysticetes studied in the LFS SRP; thus, the commenters suggest that NMFS should revise its “negligible impact determination” accordingly.

Response:
The Navy's LFS SRP was designed to study those marine mammals most susceptible to LF sound, sperm and large baleen whales. Beaked whales are mid-frequency specialists, not LF specialists, which was the reason for not including them in the LFS SRP. Moreover, because of their unknown habitats and rare sightings, there is great difficulty in attempting to study these species (see RTC MMIC22). Results from the interim report on the Bahamas strandings (DoC and SECNAV, 2001) cannot be extrapolated to estimate potential risk to these animals from SURTASS LFA sonar because of the differences in frequency regimes (100-500 Hz vs. 3,000-4,000 Hz). Furthermore, as mentioned previously, DOC and SECNAV (2001) state, “SURTASS LFA, another Navy sonar, had no involvement in this (beaked whale stranding) event.” However, on July 25, 2001, NMFS issued a modification to a scientific research permit held by Dr. Peter Tyack to undertake studies on beaked whales. In addition, NMFS is recommending research on beaked whales be funded under the SURTASS LFA long-term monitoring (LTM) program.

In the interim, because NMFS does not expect tissue damage to occur from sound exposure below SPLs of 180 dB and because of the high detection rate of the HF/M3 sonar and other monitoring requirements ensuring SURTASS LFA sonar shutdown when any marine mammal (including any beaked whales) approaches or enters the 180-dB LFA mitigation zone, the risk of injury to a marine mammal is near zero. Moreover, the monitoring and mitigation protocols proposed for employment of SURTASS LFA will preclude employment in narrow and deep channels surrounded by land such as those in the Bahamas (22-km/12-nm restriction).

Regarding its negligible impact determination, until scientific evidence is forthcoming on stock discreteness of the Bahamian population of beaked whales, NMFS must conclude that, while locally significant, it is highly unlikely that stock or species level impacts occurred to the beaked whales as a result of the Bahamas incident.

Similarly, it is unlikely that SURTASS LFA sonar operations (which would not operate in areas similar to the Bahamas incident) would cause stock level impacts. Therefore, as indicated later in this document, NMFS believes that SURTASS LFA sonar operations are unlikely to have more than a negligible impact on affected species or stocks of marine mammals.

Comment MMIC29:
There is no evidence to support the Navy's position in the Final EIS that the difference in frequency of the sonar in the Bahamas stranding event makes LFA particularly safe or that beaked whales are the only species vulnerable to strandings. The Bahamas incident demonstrates that such impacts are possible and are of concern for LFA sonar.

Response:
Please see previous RTCs regarding the potential for strandings to be caused by SURTASS LFA sonar.

Comment MMIC30:
NMFS should await the final report on the Bahamas stranding investigation before issuing a small take permit to the Navy.

Response:
The interim report on the Bahamas stranding event was released to the public in December 2001 (DOC and SECNAV, 2001). The final report will not be completed until final necropsy analyses have been completed. However, because the analyses regarding the cause of the beaked whale stranding event needed by NMFS to make its determinations on the Navy's small take application are in the interim report, NMFS does not need to delay decision-making until the final report is completed and released to the public.

Comment MMIC31:
One commenter stated, “* * * in the Navy's treatment of the Bahamas strandings (Final EIS at 3.2-47), where it suggested that the lack of observed strandings during the LFS SRP rules out any conclusion that might be made about potential impacts on the basis of that incident (and subsequent investigations).”

Response:
There is no discussion in the Final EIS or in TR 1 of the lack of strandings during the LFS SRP. What was stated was that there is no evidence that beaked whales are more sensitive to LF sound than the baleen whales studied during the LFS SRP. However, as noted by the commenter, there was a “lack of observed strandings” during all three phases of the LFS SRP. For additional information on events potentially related to LFS SRP Phase III, see the Final EIS (RTC 4-5.25). The Navy did not, as suggested by the commenter, use this lack of strandings as proof of absence of harm.

Comment MMIC32:
Was the Bahamas stranding the results of the Navy's testing of super-cavitation torpedoes?

Response:
It was not. Readers interested in super-cavitation torpedoes are directed to Ashley. 2001. Scientific American 285(5).

Resonance

Comment MMIC33:
Resonance effects in air/gas cavities or spaces can cause injury (tissue damage) or mortality to marine mammals, such as the Greece and Bahamas beaked whale strandings. Air space resonance produced by LFA sonar could cause tissue damage to the lungs of many cetaceans and can inflict injury at frequencies to which creatures are not acoustically sensitive. The resonance would be substantially larger than the displacement associated with mid-frequency sonar. Can the LFA source stimulate resonance sufficient to cause injury to marine mammals? Ten seconds could be enough to induce resonance. Most underwater acousticians would have considered the tactical sonar to be less likely than LFA sonar to cause the bubble resonance phenomena due to the relatively short duration and high sweep rates typical of tactical sonar compared to LFA. One organization received 18 comments on resonance applicability to LFA.

Response:
The concept that resonance will increase stress on tissue to the point of damage is in reality two separate concepts: resonance and tissue damage. Cudahy and Ellison (2002) state that resonance does not equal damage and damage is not always linked to resonance. So the issue is not resonance in air/gas cavities, but tissue damage, whether it is caused by resonance or by other means. As discussed in detail under RTC MMIC20, the potential for
in vivo
tissue damage to marine mammals from exposure to underwater LF sound will not occur at a level less than 180 to 190 dB (Cudahy and Ellison, 2002). Please refer to RTC MMIC20 for more information.

Therefore, unless an animal is within the 180-dB SURTASS LFA sonar mitigation zone, there should be no physical damage to body systems or tissues. Because of the mitigation measures, the potential impact to any marine mammal stock from injury is considered negligible. Whether or not SURTASS LFA sonar is more or less likely than a mid-frequency, shorter pulse, sonar to cause resonance is not relevant to the impact analysis in this case because marine mammals are very unlikely to be exposed to injurious levels (above 180 dB RL). Likewise, whether or not 10 seconds could be enough to produce resonance is also not relevant in this case for the same reason.

Comment MMIC34:
More studies are required on lung volume resonance in marine mammals which require more detailed studies to model lung responses over a range of volumes and diving depths. The Navy has the capability and resources to conduct a thorough review and modeling of all this data, including, for example, full finite element analysis of the ears and air spaces of the Cetacea and other marine mammals to LFA sonar sounds to access the potential for tissue damage, hearing loss, and death. It is unclear what frequency ranges cause resonance in each species and over what dive depths. Calculated resonance frequencies for marine animals fall within the LFA frequency range. Cranial air space resonance of beaked whales is known to be about the center frequency of LFA, so resonance should be expected. One commenter listed several anatomical considerations concerning airspaces that may be vulnerable to LFA-frequency-induced resonance. These included the lungs and others, such as sinuses. Calculations show that resonance would occur in a bottlenose dolphin lung at 100 Hz at 34 m (111.5 ft) depth to 500 Hz at 500 m (1640 ft) depth and a beaked whale at 100 Hz at 151 m (495 ft) depth to 500 Hz at 1,042 m (3419 ft) depth.

Response:
There is abundant anatomical evidence that marine mammals have adapted to dramatic fluctuations in pressure. For example, marine mammal lungs are reinforced with more extensive connective tissues than their terrestrial relatives. These extensive connective tissues, combined with the probable collapse of the alveoli at the depths at which significant SURTASS LFA signals can be heard, make it very unlikely that significant lung resonance effects could be realized. Alveolar collapse is not the only change in the lungs. The trachea can also collapse because cartilage armor rings are often incomplete. Air that does not escape the alveoli is quickly absorbed during diving due to the high partial pressure of the gas (Berta and Sumich, 1999). Complete lung collapse occurs at depths of 25 to 50 m (82 to 164 ft) for Weddell seals (Falke et al., 1985), 75 m (246 ft) for the bottlenose dolphin (Ridgway and Howard, 1979), and probably occurs in the first 50 to 100 m (164 to 328 ft) for most marine mammals (Berta and Sumich, 1999). Also as determined by Cudahy and Ellison (2002), tissue damage is not expected to occur in marine mammals below 180 dB RL.

Based on these reasons, NMFS does not believe that additional research is necessary on the potential for resonance effects in marine mammals due to LF sound prior to SURTASS LFA sonar

operations being authorized to incidentally harass marine mammals, but such research should occur simultaneously with SURTASS LFA sonar operations (i.e., small take authorization holders are required through statements by Congress to conduct appropriate research to address impacts and ways to mitigate those impacts). Moreover, NMFS understands that such research is already underway (e.g., finite element modeling is being conducted on beaked whale skulls collected at the 2000 Bahamas stranding, and studies of tissue and air-space resonance in the head are being conducted by two independent research teams) and additional research may be conducted by the Navy, the National Science Foundation or the National Institutes of Health in the future.

Comment MMIC35:
One commenter submitted a paper titled “Air-space Resonance and Other Mechanisms Which May Cause Tissue Damage in Cetaceans” as an attachment to his comments. This paper postulates that: (1) Air space resonance could cause damage to some of the large sinus cavities of cetaceans and that LFA sonar could cause lung damage due to resonance, (2) LFA sonar could cause resonance in the lungs and sinuses and a resonance at the same frequency of the tympanic bone of the middle ear, (3) LFA sonar could induce panic and subsequent problems with equalization, (4) LFA sonar could possibly cause bubble growth in blood vessels, and (5) LFA sonar signals are of long enough duration to cause resonance.

Response:
Resonance does occur in natural systems. However, an analysis subsequent to the Final EIS by Cudahy and Ellison (2002) of the potential for resonance from SURTASS LFA signals to cause injury does not support the conclusions in the commenter's paper. The issue is not resonance, but tissue damage. The potential for
in vivo
tissue damage to marine mammals from exposure to underwater LF sound will occur at a damage threshold on the order of 180 to 190 dB (Cudahy and Ellison, 2002) (see RTC MMIC20). The maximum SPL of 160 dB proposed by the commenter is based on a degree of tuning, or Q value, of 10. (
Note:
The Q of a system denotes how sharply the system responds at resonance). In other words, Q designates how much higher a system's resonance frequency response is compared to its response at non-resonance frequencies. If Q is high, the peak in frequency response is high; whereas, if Q is small, the frequency response peak is shallow (Prout and Bienvenue, 1990). Critical issues to consider in examining resonance effects are the tuning of the resonance and the damping due to contiguous body structures. The Q value that has been measured
in vivo
in the lungs (of pigs and humans) is a Q from 3 to 5 (Martin
et al.
, 2000). There are no data to support the use of a Q value of 10 as a good estimate of the degree of tuning in cetacean air-filled spaces. In general, the internal organs of mammals are very highly damped. Examining fishes, extensive measurements of the Q of swim bladders at resonance (covering a wide range of species and sizes) support an
in vivo
range of Q from 1.0 to 6.1 (Love, 1978). Thus, an educated estimate of the Q for other gas-filled structures, which are much less free to move than the lung, would generally be very small, even less than the (1<Q<6) range encompassing both lung and fish swim bladder measured results (Cudahy and Ellison, 2002). Therefore, resonance calculations based on a Q value of 10 are incorrect.

For reasons mentioned in RTC MMIC34, there is abundant anatomical evidence that marine mammals have adapted to dramatic fluctuations in pressure. Please refer to that RTC for further response. In addition, the nasal air sacs are too small to be relevant to LFA transmissions. Furthermore, these nasal diverticuli are clearly involved in sound production (Heyning and Mead, 1990). The pressure fluctuations that accompany the emission of echolocation clicks or communicative sounds must be substantial, so these tissues should also be relatively resistant to damage from external sound sources.

It is likely that marine mammals, which have evolved in an ambient hydrostatic pressure environment spanning several orders of magnitude (1:10
3
), would be pre-disposed to have an innately rugged physiology for handling pressure changes. Therefore, it is unlikely that they would experience equalization problems. Crum and Mao (1996) stated, “For SPL's below about 190 dB, however, except under relatively extreme conditions of supersaturation, significant bubble growth is unexpected.” This is covered in the Final EIS RTC 4-9.4.

In summary, resonance can occur in marine animals, but this resonance does not necessarily lead to injury. Scientific data noted above demonstrate that in order for LF sound to cause injury, the SPL must be above 180 dB. Due to the 180-dB SURTASS LFA sonar safety zone and the additional 1-km buffer zone, the probability of any marine mammal being exposed to received levels at or above 180 dB, with or without resonance, approaches zero. Therefore, the above evidence does not support the claims by the commenter that LFA sonar signals will cause air space resonance, tissue damage or injury to marine mammals.

Comment MMIC36:
One commenter stated, “We would like to have had the time to see if there are co-resonances, in which, for example, a lung at resonance becomes a sound source of its own. If the Q of the system is 10, then the re-radiation of the lung is actually 10 × the incoming sound pressure that sent it into resonance. Therefore, the lung becomes an acoustic amplifier. Then, in calculating the effects of LFAS, one must consider any resonant cavity to be a sound source LOUDER than the original LFAS signal, just multiply by Q.”

Response:
From a purely physiological standpoint, it could be hypothesized that the lung could possibly become an acoustic amplifier. However, there are no data to support a Q of 10 as a good estimate of the degree of tuning in an air-filled space; and in general, the internal organs of mammals are highly damped (Cudahy and Ellison, 2002). These authors cite data for a range of Q from 1 to 6 encompassing both lungs and fish swimbladders. Further, human and pig data collected
in vivo
indicate that at the resonant frequency of the lung, tissue damage occurs above 180 dB SPL (see TR 3 and Cudahy and Ellison, 2002). Since the data were collected at resonance, any amplification would have been included in the response of the lung to the sound, regardless of the Q value.

Comment MMIC37:
The Final EIS analysis did not consider Minnaet's and Andreeva/Barham's equations that relate bubble size to resonance frequency and show that there are air cavity volumes of all sizes that may resonate in marine animals.

Response:
The consideration of Minnaet's and Andreeva/Barham's equations relating to resonance are not relevant to the analysis in the Final EIS because the best supportive evidence as documented indicates that below 180 dB RL SURTASS LFA signals would not cause injury. For additional information, see the Final EIS Subchapter 1.4.2 and RTC MMIC35. Because of mitigation protocols, the probability of a marine mammal being undetected within the 180-dB SURTASS LFA mitigation zone during transmission approaches zero. The subsequent analysis, mentioned previously, by Cudahy and Ellison (2002) on the potential for resonance from LFA signals to cause injury supports this conclusion.

Comment MMIC38:
One commenter stated, “Further, not all marine life

damage can be attributed to air cavity resonance alone. Damage to hearing apparatus of marine mammals such as uncovered by Dr. Darlene Ketten from Woods Hole illustrates my point. The entry to the brain and on to the hearing apparatus was through a nerve foramen from a sinus cavity. The air cavity of the sinus will not vibrate as a bubble because the bony sinus cavity presents a different acoustical impedance to the sonar. The whole of the lung/bronchial tubes/trachea/sinus/air-volume complex must be considered. Modeling of this complex air volume may be possible by considering the lung to vibrate like a bubble and the remaining part act as a Helmholtz resonator. A coupled resonant system such as this can explain the punch through at the nerve foramen site which is soft compared to the bony sinus cavity thus concentrating the displacement on the soft foramen site into the brain where Ketten observed the bloody mass and hearing apparatus trauma.”

Response:
This comment is an untested hypothesis presented as to a possible coupled resonance mechanism for the injury to the Blainville's beaked whale that stranded during the Bahamas standing event in March 2000. As noted in DOC/SECNAV (2001), the necropsy found a unilateral temporal subarachnoid hemorrhage with blood clots bilaterally in the lateral ventricles. In simpler terms, there was a blood trail in at least one animal that could be traced to a hemorrhage in a discrete region of a fluid space around the temporal regions and within the ventricle of the brain. There was no conclusion drawn by the interim report stating that this was, or could have been, caused by coupled resonance causing the “punch through” at the nerve foramen site into the brain. In fact the report stated, “The actual mechanisms by which these sonar sounds could have caused animals to strand, or their tissues to be damaged, have not yet been revealed, but research is underway.”

The commenter discusses the lungs/bronchial tubes/trachea/sinus (air sac) complex. He also comments upon the sinuses surrounding the middle ear. The tympano-periotic structure has a neural connection to the brain, and it was along this neural pathway that he stated Dr. Ketten reported damage in the Bahamas stranding animals. However, there is no connection between the respiratory and auditory systems. Any resonance that may occur in the respiratory system has no physical connection to the bulla and brain. In fact, the bulla appears to be acoustically isolated by ligaments and the peri-tympanic sinuses to prevent any bony sound conduction to the ear (Ketten, 1997), emphasizing the auditory pathway from the pan bone in the lower jaw. Therefore, the connection between any possible resonance (coupled or not) in the respiratory system and the bulla/brain is unlikely.

Finally, the SPL threshold for the potential for
in vivo
tissue damage due to exposure to underwater sound, including resonance effects, is on the order of 180 to 190 dB (Cudahy and Ellison, 2002). In conclusion, the above hypothesis does not appear to be valid.

Additional Marine Mammal Impact Concerns

Comment MMIC39:
Can LFA reduce the resolution power (capability) of echo-locating by marine mammals? For example, will a dolphin's ability to distinguish heads from tails on a coin be affected?

Response:
No. Dolphin echolocation utilizes high frequency sound and SURTASS LFA sonar is low frequency. Therefore, SURTASS LFA sonar will not affect the resolution capability of echo-locating marine mammals.

Comment MMIC40a:
One organization believes that potential non-detectable and unmonitored effects of SURTASS LFA sonar include increases in miscarriage rates, increased vulnerability to other anthropogenic threats (such as entanglement in fishing gear or susceptibility to ship strikes), decreases in feeding rate, changes in lactation rates, increased stress, changes in navigational abilities, potential hearing loss, etc. Even the Navy concedes that incidental takes consisting of short-term behavioral modifications will occur outside the 180-dB isopleth. Since these effects are typically undetectable, it will be impossible to assess or monitor these effects. As a result, the commenter does not believe that NMFS can make a finding of negligible impact.

Response:
This comment combines impacts that could potentially occur due to an injury to hearing and those that are short-term behavioral effects due to the SURTASS LFA sonar sounds. In order for injury-related effects to potentially occur, the HF/M3 sonar would need to be ineffective at locating marine mammals. This, as noted elsewhere in this document is unlikely (see Mitigation Concerns). Moreover, in order for a marine mammal to be injured, the HF/M3 sonar would need to have missed the animal through the several acoustic sweeps that it would make prior to the animal getting close enough to the projectors to be injured. Potential behavioral effects, which are the principal means of taking being authorized by this action, have been discussed throughout this document and the Navy's Final EIS. NMFS' determination of negligible impact is discussed later in this document.

Comment MMIC40b:
There is no way to know what becomes of stressed or confused animals in offshore waters due to noise pollution. The cause of entanglements, ship collisions, and other such incidents cannot be predicted or recognized.

Response:
There is no scientific information to support a hypothesis that sound from SURTASS LFA sonar will increase stress or confusion in marine mammals. Because of the relatively short duty cycle, the water depth of the CZ ray path, the movement of marine mammals in relationship to the SURTASS LFA sonar ship, and the effectiveness of the tripartite mitigation program, few marine mammals are likely to be affected. In order to receive more than one “ping,” during a normal 8-hr vessel leg, an animal would need to match the ship in speed and course direction between pings. Also, entanglement in fishing gear, collisions with ships, or strandings appear to result from vestibular effects to the inner ear associated with explosives or being very close to a loud, underwater noise. However, while there is no indication that this would result from being within the 180 dB safety zone for SURTASS LFA sonar, in the effects analysis of the Final EIS, the Navy presumes that 100 percent of the marine mammals within the 180 dB zone would receive an injury even though animals may not actually be injured.

Comment MMIC41:
The assumption in the Final EIS analysis that animals are only subject to acoustic stress during LFAS operations is not correct. An animal knowing that the presence of the SURTASS LFA vessel indicates a periodic, unpredictable, annoying noise source, which interferes with their behavior, causes stress.

Response:
This assumption presumes that marine mammals will associate a visual cue (the SURTASS LFA sonar vessel) with a noise (presumably an annoying noise). This is unlikely unless the marine mammal can associate a cause and effect between the two cues based on earlier experience. Although this has been known to occur in certain situations (
e.g

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Source: Frix Law Library, https://www.frixlaw.com/law-library/documents/fr%3A02-16853. Public record. Not legal advice.