NMFS, upon application from the University of California San Diego, Scripps Institution of Oceanography (Scripps), is issuing regulations to govern the unintentional take of a small number of marine mammals incidental to the continued operation of a low frequency (LF) sound source by Scripps.

NMFS, upon application from the University of California San Diego, Scripps Institution of Oceanography (Scripps), is issuing regulations to govern the unintentional take of a small number of marine mammals incidental to the continued operation of a low frequency (LF) sound source by Scripps.

Taking and Importing Marine Mammals; Taking Marine Mammals Incidental to

Operation of a Low Frequency Sound Source by the North Pacific Acoustic

Laboratory

Friday, August 17, 2001

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

ACTION: Final rule.

SUMMARY: NMFS, upon application from the University of California San Diego, Scripps Institution of Oceanography (Scripps), is issuing regulations to govern the unintentional take of a small number of marine mammals incidental to the continued operation of a low frequency (LF) sound source by Scripps. The sound source was previously installed off the north shore of Kauai by the Acoustic Thermometry of Ocean Climate (ATOC) project. Issuance of 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 conducting the activity; such authorization is not within the jurisdiction of the Secretary. Rather, these regulations authorize the unintentional incidental take of marine mammals in connection with such activities and prescribe methods of taking and other means of effecting the least practicable adverse impact on the species and its habitat, and on the availability of the species for subsistence uses.

DATES: Effective from September 17, 2001, through September 17, 2006.

ADDRESSES: Copies of the Scripps' application and NMFS' Biological Opinion 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). A limited number of copies of the Final Environmental Impact Statement (final EIS), issued by the Office of Naval Research, Department of the Navy (ONR) for this activity, are available from Marine Acoustics Inc., 809 Aquidneck Ave., Middletown, RI 02842, attn. Kathy Vigness Reposa, 401-847-7508. -

Comments regarding the burden-hour estimate or any other aspect of the collection of information requirements contained in this 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) 713-2055, ext. 128.

SUPPLEMENTARY INFORMATION:

Background

Section 101(a)(5)(A) of the Marine Mammal Protection Act (16 U.S.C. 1361 et seq.) (MMPA) 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 governing the take are issued. -

Permission may be granted for periods of 5 years or less if the Secretary finds that the taking will be small, will have no more than a negligible impact on the species or stock(s), and will not have an unmitigable adverse impact on the availability of the species or stock(s) for Arctic Ocean 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 May 21, 2000, NMFS received an application for an incidental, small take authorization under section 101(a)(5)(A) of the MMPA from Scripps to take a small number of marine mammals incidental to the continued operation of a LF sound source previously installed off the north shore of Kauai, HI as part of the ATOC project. The principal funding agency for the proposed action is ONR. A final decision on whether to use the acoustic sound source and its seabed power cable for the North Pacific Acoustic Laboratory (NPAL), in order to combine a second phase of research on the feasibility and value of large- scale acoustic thermometry with long range underwater sound transmission studies and marine mammal monitoring and studies, will be made by Scripps and ONR based, in part, on their findings and determinations made under the National Environmental Policy Act (NEPA). Draft and final EISs have been prepared by the ONR. NMFS is a cooperating agency, as defined by NEPA, in the preparation of these documents.

Project Description

Acoustic thermometry is a method for obtaining information about the temperature field in the ocean from precise measurements of the travel times of sound pulses transmitted through the ocean. It is also a technique for acoustic remote sensing of the ocean interior, in which the properties of the ocean between the acoustic sources and receivers are determined, rather than the properties of the ocean at the instruments as is the case for conventional thermometers and current meters.

The basic principle behind acoustic thermometry is that, because sound travels faster in warm water than in cold water, sound travel time is a direct measure of the average temperature between source and receiver. The travel time of a sound pulse from a source near Kauai to a receiver in the western North Pacific Ocean, for example, will decrease if the ocean in between warms up and will increase if the ocean cools down. Measuring average ocean temperatures over time may answer questions related to global climate change.

The NPAL acoustic project takes advantage of an acoustic "waveguide" deep within the ocean that carries sounds over very long distances. This feature, known as the "sound channel" or sound fixing and ranging (SOFAR) channel, is at the ocean depth where the speed of sound is at a minimum. Above the SOFAR channel, sound travels faster because the water is warmer. Below the SOFAR channel, sound travels faster because the pressures are greater. Sounds that would otherwise spread to higher or lower depths are refracted (bent) back toward the SOFAR channel axis by this difference in speeds. The net effect is that the sound channel very efficiently transmits sounds for long distances. This effect also tends to limit sounds that are trapped in the SOFAR channel from being detectable at depths outside of the channel. -The sounds to be produced by the NPAL source are digitally coded, low frequency rumbles at a pitch comparable to the low notes of a cello. The same digital sequences are repeated a number of times and combined at the receivers. This allows a signal to be detected beneath the ambient background noise which, in turn, permits use of a less intense sound source. The receiving stations use advanced digital processing techniques similar to those used to retrieve data from deep space probes, to detect signals after traveling great distances through the SOFAR channel. -

Long-range underwater sound transmission studies are needed: (1) To improve the understanding of the basic principles of LF, long-range underwater sound transmission (i.e., acoustic propagation) in the ocean; (2) to determine the effects of ocean environmental variability on acoustic signal stability and coherence; (3) to study the seasonal and annual variations in acoustic conditions in the North Pacific and the impact of environmental variability on acoustic propagation; and (4) to determine the fundamental limits to acoustic signal processing at long-range imposed by the ocean environment.

The original ATOC feasibility project demonstrated that acoustic thermometry is a powerful tool for making routine measurements of large-scale ocean temperature variability and heat content. The key results obtained to date are: (1) Acoustic travel times can be measured with a precision of about 20-30 milliseconds at 3000-5000 km (1620-2700 nm) ranges; (2) range- and depth- averaged temperature estimates made from the acoustic travel-time data are consistent with direct temperature measurements made with instruments lowered from ships (Worcester et al., 1999); (3) the observed travel time changes can be clearly related to known ocean processes; and (4) the range and depth- averaged temperatures derived from ATOC are consistent with, and complementary to, related estimates derived from measurements of sea-surface height.

The purposes for conducting the proposed second-phase of large-scale acoustic thermometry research are: (1) To test the feasibility and value of large-scale acoustic thermometry; (2) to study the behavior of sound transmissions in the ocean over long distances; (3) to study seasonal and interannual ocean variability associated with ocean phenomena such as El Nin6o, La Nin6a, and the Pacific Decadal Oscillation; (4) to use acoustic thermometry data in combination with a variety of other data types, including satellite altimeter data, surface drifter data, surface mooring data, and others to test and constrain computer models of ocean circulation in order to gain a better understanding of ocean variability and the earth's changing climate; and (6) to make an objective assessment of the value of acoustic methods for remote sensing of the ocean interior as one component of an integrated ocean observing system for ocean weather and climate. This second phase of acoustic research will require a long time series of acoustic measurements in order to determine whether the acoustically-derived time series of large-scale ocean temperature and heat content variability prove to be as valuable as anticipated in studying seasonal and interannual ocean variability.

Under the proposed action, which is for Scripps to operate the sound source previously installed off the north shore of Kauai by the ATOC project, the seabed power cable and sound source from the ATOC project would remain in their present locations offshore of Kauai, and transmissions would continue with approximately the same signal parameters and transmission schedule used in the earlier ATOC project. The typical schedule would consist of six 20-minute (min) transmissions (one every 4 hours), every fourth day, with each transmission preceded by a 5-min ramp-up period during which the signal intensity is gradually increased, representing an average duty cycle of 2 percent. With the possible exception of short duration testing with duty cycles of up to 8 percent, or equipment failure, this schedule would continue for a period of 5 years. In this context, short duration testing refers to a maximum of 2 months of testing per year at a duty cycle higher than 2 percent. The signals transmitted by the source would have a center frequency of 75 Hertz (Hz) and a bandwidth of approximately 35 Hz (i.e., sound transmissions are in the frequency band of 57.5-92.5 Hz). Approximately 260 watts of acoustic power would be radiated during transmission. According to Scripps, the signal parameters and source level in the ATOC project have been found to provide adequate, but not excessive, signal-to-noise ratios in the receiver ranges of interest. At 1 meter (m)(3.3 feet (ft)) from the source (at 807 m (2,648 ft) water depth), sound intensity (i.e., source level) would be about 195 decibels (dB) referenced to the intensity of a signal with a sound pressure level (SPL) of 1 microPascal (1 MUPa).

Average ambient noise levels in the 60-90 Hz band offshore central Kauai can be 76-98 dB (with various degrees of shipping traffic) and are expected to be higher (a6105 dB) when humpback whales are present. At the water's surface above the NPAL source, the received level from the NPAL source is not expected to be louder than 137 dB when the source is on. The received level in the top 100 m (328.1 ft) from the water surface, when the source is on, has been measured to decrease to about 120 dB at 5 km (2.7 nm) shoreward of the source. The near-surface NPAL received level is predicted to decrease to about 120 dB at 7.5 km (4 nm) seaward of the source. Underwater sound levels in the area surrounding the NPAL source are expected to be: 140 dB at 245 m (804 ft) water depth (562 m (1844 ft) from the source); 145 dB at 491 m (1611 ft) water depth (316 m (1037 ft) from the source); 150 dB at 629 m (2064 ft) water depth (178 m (564 ft) range around the source); and 165 dB at 775 m (2543 ft) water depth (32 m (105 ft) range around the NPAL source (ONR/NMFS, 2000; ARPA/NMFS, 1995). -

Comments and Responses

On December 22, 2000 (65 FR 80815), NMFS published a proposed rule to authorize Scripps to take small numbers of marine mammals incidental to the continued operation of a LF sound source previously installed off the north shore of Kauai, HI, and requested comments, information, and suggestions concerning the request and the regulations that would govern the taking by harassment of certain species of marine mammals. During the 45-day public comment period, NMFS received letters from one citizen, the Marine Mammal Commission (MMC), the Hawaii Department of Business, Economic Development and Tourism (State of Hawaii), the Humane Society of the United States (on behalf of itself, Earth Island Institute and the Natural Resources Defense Council) (HSUS), and from the Whale and Dolphin Conservation Society (WDCS). Some comments by the MMC regarding minor text edits modifications have been incorporated without further discussion in this document. -

Activity Concerns

Comment AC1: The MMC notes that the term "short duration" should be described in reference to duty cycles of up to 8 percent.

Response: In the preamble to the proposed rule, NMFS stated: "[W]ith the possible exception of short duration testing with duty cycles of up to 8 percent, or equipment failure, this (NPAL transmission) schedule would continue for a period of 5 years." In this document, "short duration testing" refers to the maximum of 2 months of testing per year at a duty cycle higher than 2 percent. This increased duty cycle would not occur during the humpback whale season (February through April), and would not have any single transmission longer than 2 hours in duration. For example, an 8 percent duty cycle might include 20-minute transmissions at 4-hour intervals every day, instead of every fourth day. Another example could involve transmitting the 20-minute signal on the hour for 24 hours followed by 72 hours with no transmissions, repeated up to 15 times over the 2-month 8-percent duty cycle period.

Comment AC2: The MMC notes that the discussion does not, but should, explain that received sound levels at different distances from the source are mean or modal estimates and that certain environmental conditions could cause sound focusing, thereby resulting in received levels greater than estimated at various distances from the source. -

Response: NMFS agrees that SPLs at different distances may be affected slightly by water and bottom characteristics. This is especially likely for upslope propagation and is explained in some detail in ONR's final EIS. However, sound focusing is likely to occur only with surface ducting; with the NPAL source located at a depth of 807 m (2,648 ft), surface ducting is very unlikely to occur.

MMPA Concerns

Comment MMPA1: The MMC notes that, while any significant behavioral response by a marine mammal no doubt would constitute Level B harassment, it is not clear that other types of disturbance that cause disruption of behavioral patterns would not constitute harassment. As such, NMFS should more clearly explain how the distinction it seeks to draw between significant and other behavioral responses conforms to the statutory definition of Level B harassment. The MMC recommends also that NMFS more clearly describe what would constitute a significant behavioral response. -

Response: NMFS clarifies that, for small take authorizations (as opposed to intentional takings), NMFS considers a Level B harassment taking to have occurred if the marine mammal has a significant behavioral response in a biologically important behavior or activity. The term "harassment" is defined in the MMPA as "any act of pursuit, torment, or annoyance which . . . (ii) has the potential to disturb a marine mammal or marine mammal stock in the wild by causing disruption of behavioral patterns, including, but not limited to, migration, breathing, nursing, breeding, feeding, or sheltering." -

In this context, a behavioral pattern means a composite of biological traits characteristic of an individual or of a species. Therefore, to disrupt a behavioral pattern, the activity would need to disrupt an animal's normal pattern of biological traits or behavior, not just cause a momentary reaction on the part of a marine mammal. Therefore, if the only reaction to an activity on the part of the marine mammal is within the normal repertoire of actions that are required to carry out the behavioral pattern for that species of marine mammal, NMFS considers the activity not to have caused an incidental disruption of the behavioral pattern, provided the animal's reaction is not otherwise significant enough to be considered disruptive due to length or severity. For example, if there is a short-term change in breathing rates or a somewhat shortened or lengthened diving sequence that is within the animal's normal range of breathing patterns and diving cycles but there is not a disruption to the animal's overall behavioral pattern (i.e., the changes are not biologically significant), then these responses do not rise to a level requiring a small take authorization or, if under a small take authorization, does not constitute an incidental take. -

Examples of significantly disruptive or severe behavior would be where pinnipeds flee a haulout beach or rookery en mass due to a disturbance, or animals either leave an area of habitation for a period of time, or diverge significantly from their migratory path to avoid either an acoustic or a visual interference. For these two mentioned situations, non-significant behavioral responses would be when only a few pinnipeds leave the haulout or mill-about, but many pinnipeds alert to the disruption; or when marine mammals make minor course corrections that are not discernable either to observers or directional plotting, and which require statistical manipulation in order to determine that a course correction has taken place. For the action under consideration in this document, it is the behavioral response of the humpback and possibly sperm whale to the NPAL signal that is the biological response that is considered to be a taking by harassment. -

Comment MMPAC2: The HSUS believes that NMFS has used the NPAL proposed rulemaking to establish a standard for Level B (acoustic) harassment, which appears to extend well beyond this project. This new standard, which NMFS has referred to as "biological significance," would count as "takes" only those activities with the potential to affect the reproduction and survival of a protected species. The HSUS believes that NMFS is making discriminations that are non-conservative judgements in violation of the MMPA. NMFS is obligated to use the definition found in the MMPA (for Level B harassment) in calculating species take and must include in its tally any animal whose behavioral patterns might potentially be disrupted. The Agency's failure to do so here, and its extension of this failure to a broadly applied rule, represents a rewriting of law and an offense to the conservative intent of the MMPA. -

Response: Reproduction and survival effects are used by NMFS to determine whether an activity is having a negligible impact on marine mammals, not whether an incidental take is occurring. Negligible impact determinations are based on the impact the activity might have on a species' or stocks' annual rates of recruitment (reproduction) or survival (50 CFR 216.103). Because negligible impact determinations are based, in part, on an activity's impact on a species' or stock's survival, this is far more significant to the conservation of marine mammal species and stocks than NMFS' consideration of what constitutes a significant behavioral response in a biologically important activity under Level B harassment. -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. -

Comment MMPAC3: The MMC notes that, in a previous rulemaking for taking marine mammals incidental to conducting a shock trial, the MMC expressed a concern that NMFS' proposal to define Level B harassment from explosive detonation events exclusively in terms of temporary threshold shift (TTS) was tantamount to concluding that behavioral changes not related to TTS are biologically insignificant and do not constitute harassment as defined in the MMPA. Such a conclusion, the MMC contends, seems inconsistent with the statutory definition of the term harassment and needs to be reconsidered or further justified. -

Response: As stated in the final rulemaking for issuance of a small take authorization for the U.S. Navy incidental to conducting the shock trial (66 FR 22450, May 4, 2001), NMFS clarified that the criterion limiting Level B harassment to behavioral responses that are possible as a result of receiving an impairment to hearing (i.e., TTS) was limited to single-event explosions, not multiple explosive events spaced over a relatively short period of time in the same vicinity, nor to impulse or intermittent/continuous noise sources such as seismic, Navy sonars, and oceanographic instrumentation. These other listed activities have at least the potential to cause significant behavioral responses on the part of marine mammals that are not related to behavioral disruptions caused by TTS. Because NPAL is considered an intermittent noise source, and has, therefore, the potential to result in non- TTS related behavioral responses, the comment is not relevant to the discussion in this rulemaking. Reviewers interested in NMFS' response to this concern of the MMC should review the previously mentioned rule, specifically NMFS' response to comment 3 in that document. For intermittent sounds, Level B harassment would include both TTS-related behaviors and behavioral responses resulting from noise levels lower than those that might potentially cause TTS. However, for the NPAL project, as mentioned elsewhere in this document, TTS is unlikely to occur. -

Comment MMPAC4: The MMC recommends NMFS more clearly describe what is meant by "far exceed." -

Response: The sentence referenced by the MMC states: "Few data on the effects of non-explosive sounds on hearing thresholds of marine mammals have been obtained; however, in terrestrial mammals, and presumably in marine mammals, received sound levels must far exceed the animal's hearing threshold for there to be any TTS." The statement is meant to apply to marine mammals in general since the difference between hearing threshold (level where one could hear the quietest sounds) and a level that might cause onset-TTS is expected to vary among marine mammal species and even among individual animals. However, the term "far exceed" is based on Richardson et al.'s's (1991, 1995) conclusion, that, based upon studies on humans, SPLs of 80 to 100 dB and 130 dB over threshold are necessary in order to cause annoyance and for injury, respectively, in odontocetes (see response to comment MMPAC5 for more information). -- -

Comment MMPAC5: The WDCS quotes Ketten (1998) that "sublethal impacts may ultimately be as devastating as lethal impacts, causing death indirectly through behavioral reactions, such as panic, as well as impaired foraging or predator detection, but the potential for this type of extended or delayed impact from any sound source is not well understood for any mammal." The WDCS believes that temporary lack of predator avoidance skills may clearly lead to the death of an individual cetacean. This leads WDCS to conclude that TTS should be classified as a Level A harassment. -

Response: For reasons provided in response to comment 26 in the Federal Register document for issuance of a small take authorization for shock testing the USS WINSTON S. CHURCHILL (66 FR 22450, May 4, 2001), NMFS does not believe the evidence warrants TTS being considered as Level A harassment (i.e., injury) due to the referenced secondary effects. Please refer to that document for additional information. -

Comment MMPAC6: The HSUS quotes NMFS stating: "scientists have noted that a range of only 15-20 dB may exist between the onset of TTS and the onset of PTS . . . ." With such a narrow safety margin, the HSUS considers it non- precautionary to consider TTS to be the upper portion of the Level B harassment zone, as does NMFS. With so little known about TTS, in mysticetes in particular, it seems more prudent and precautionary to consider TTS as the lower portion of the Level A harassment zone. -

Response: The statement in the proposed rule that is quoted in the comment was incomplete. The 15-20 dB difference refers to the difference between the sound exposure levels (SELs) that cause the slightest TTS and the onset of PTS. As explained in more detail in response to comment PRC6 and in the response to comment 29 in the final rulemaking document for the shock trial of the USS WINSTON S. CHURCHILL (66 FR 22450, May 4, 2001), experiments on chinchillas have shown that this species experiences full recovery from up to 40 dB of TTS (Ahroon et al.,, 1996) from impulsive noise. However, in the absence of comparable data for marine mammals, NMFS believes it is precautionary to define the onset of PTS for marine mammals to be 20 dB of TTS. This should not be interpreted to mean that the onset of PTS results when you add 20 dB to the dB level found to cause the onset TTS in an animal, but instead means that the onset of PTS is the SEL (in dB) that would cause 20 dB of TTS. This 20 dB level would be considered conservative for chinchillas, and would likely be conservative for marine mammals. -

Because of this conservative approach, and because of the relatively low intensity of the NPAL source, and the depth of water in which the source is anchored (further attenuating the SPL), NMFS does not need to apply additional precautions, such as considering all, or a portion of, TTS to be Level A harassment. -

Comment MMPAC7: The MMC notes that the reference in the proposed rule to "lower Level A" and "upper Level B" harassment are subdivisions not reflected in either the statutory definition of harassment or the NMFS' implementing regulations. -

Response: The designations proposed by NMFS for "lower Level A" and "upper Level B" harassment have been replaced in this document by adoption of a standard that onset PTS, which is Level A harassment (injury), for marine mammals is 20 dB of TTS. -

Comment MMPAC8: The MMC notes that the discussion on intentional taking of marine mammals by whale watching and recreational boating activities should be revised to note that both intentional and incidental taking for such purposes is prohibited, absent some authorization under the MMPA. Currently there is no such authorization. -

Response: NMFS clarifies here that the whale watching industry is not authorized to "take" marine mammals, either intentionally or incidentally, therefore, harassment takings are illegal.

Proposed Rule Concerns

Comment PRC1: The MMC believes that the proposed rule relies to a significant extent on ONR's draft EIS for its interpretation and justification, and requests that previous comments by the MMC regarding the draft EIS be considered, incorporated by reference, and addressed in the NMFS final rule, as well as in ONR's final EIS. -

Response: As stated in previous documents, NMFS incorporates into its decision-making process all comments submitted on the NEPA document that accompanies a NMFS proposed action and the responses made on any recommendations and concerns. NMFS also incorporates additional information and documentation by reference. Under this action, this includes the comments submitted by the MMC and other organizations and individuals on ONR's draft EIS, and the responses made by ONR to these recommendations and concerns as provided in ONR's recently-released final EIS. Because NMFS is adopting ONR's final EIS as its own on this matter, these responses can be considered to also reflect NMFS' responses. Where necessary, this document provides additional clarification on certain issues raised by the MMC in its July 24, 2000, letter to Scripps. However, NMFS' procedures for addressing third party concerns in a NMFS final rule were provided previously (see 66 FR 22450, May 4, 2001). Please refer to that document for further information, especially response to comment 11 regarding the USS WINSTON S. CHURCHILL shock trial's small take authorization. -

Comment PRC2: The MMC believes that NMFS should have addressed the private citizen's concern about the validity of assumptions inherent in the risk analysis and the Acoustic Integration Model (AIM). As noted by the MMC in comments on the ONR draft EIS, both the risk analysis and the AIM appear to be based on two assumptions, at least one of which likely is not valid. The first is that a received sound level below 120 dB will not disturb a biologically important behavior of any of the listed species. The second is that the listed species are distributed uniformly or randomly throughout their ranges in the North Pacific. Thus, researchers familiar with the seasonal distribution, abundance, and movement patterns of the various species in the Hawaiian Islands area should be consulted to obtain a more realistic estimate of the numbers of the various species that could be exposed to received NPAL sound levels between 120 and 180 dB. -

Response: The only marine mammal species expected to be affected by the NPAL acoustic source are humpback whales, sperm whales and possibly Hawaiian monk seals. For a response regarding the assumption regarding marine mammal effects from SPLs of 120 dB or less, please refer to the response to comment MMIC6 later in this document. -

In its final EIS, ONR responded to the MMC concern about random distribution by noting that the "incidental take" analysis did not include an assumption that animals are distributed uniformly or randomly throughout their range in the North Pacific, but that the best scientific data for each species was used to model their individual dive profiles and distributions in the modeled areas. This precludes homogeneously distributed animal densities in the three dimensions profiled. Therefore, animal distribution on the large scale reflects known concentrations of animals, and distribution on the small scale represents the patchiness that is observed in the field. In reviewing the available data and information, NMFS believes that the population assessments of marine mammals, that were provided by ONR and Scripps, are the most realistic estimates available, as they are based on recent aerial surveys conducted by Hawaii-based marine mammal researchers, conducted over several years (see Mobley et al.,, 1999, 2000), and other sources of information. In addition, Dr. Mobley was a technical editor in the preparation of the ONR's draft and final EISs.

Comment PRC3: The HSUS objects to the use of proposed rulemaking for specific projects as the regulatory avenue by which broadly applied acoustic harassment standards are being promulgated. Such proposed standards should be the subject of their own, separate rulemaking. Parties who might otherwise wish to comment on broadly applied standards may miss the import of a specific project's proposed rule. -

Response: First, NMFS clarifies that no new acoustic criteria are being proposed here, only new methodology is being utilized to determine and refine estimates of levels of impact and takings. This methodology has been subject to review and comment previously under NEPA for the SURTASS LFA sonar (Navy, 1999) and NPAL (ONR, 2000). Second, the new methodology (i.e., incorporation of the AIM) is only one means NMFS is using to determine impacts on marine mammals. NMFS will also continue to assess impacts by a review of relevant research conducted on marine mammals. Finally, NMFS does not agree that separate rulemaking is needed before it can adopt criteria for acoustic harassment. This is explained in detail in response to comment 15 in the final rulemaking document for the shock trial of the USS WINSTON S. CHURCHILL (66 FR 22450, May 4, 2001). Please refer to that document for additional information on this issue. -

Comment PRC4: The HSUS notes that NMFS appears to accept that the LOA application's use of the term "prolonged" is a clarifying element of its definition of harassment that is in compliance with, rather than a novel concept not found in the MMPA. The HSUS disagrees with this apparent acceptance and asks NMFS to clarify whether the concept of "prolonged" disturbance is in compliance with, or exceeds, the criteria of the MMPA. -

Response: In response to comment 22 in the NPAL proposed rule (65 FR 80815, December 22, 2000), NMFS explained that the term "prolonged," as used in ONR's draft EIS and Scripps' small take application, implies an increase in time or duration beyond normal limits. This, NMFS stated in the response, exceeds the criterion used by NMFS that harassment must refer to a reaction that is behaviorally significant on the part of the animal in the course of that animal's conducting a biologically important activity, such as breeding, feeding, or migrating. Therefore, the term "prolonged" is not used in this document, nor in ONR's final EIS. In this context, it is the impact of the activity on the animal, not the duration of the disturbance, that is critical. NMFS explained the use of the term "behaviorally significant" previously in response to comment MMPAC1. -

Comment PRC5: The MMC notes that the NRC Report (NRC, 2000) states: "as a preliminary criterion, it seems reasonable to presume that any sound that produces a TTS of 10 dB or less in exposure episodes that are separated by nonexposure intervals that are ample to allow full recovery (at least 24 hours) does not constitute a major risk to the auditory system of a marine mammal." Therefore, the MMC questions the appropriateness of NMFS characterizing the NRC report as fully supporting that TTS does not constitute an injury. -

Response: The sentence used by NMFS is found on page 67 of the NRC (2000) report. That sentence reads: "Animals that experience only low levels of TTS are not going to be injured, suggesting TTS as a conservative standard for prevention of injury." This sentence supports NMFS' statement in the proposed rule that TTS is not an injury. The statement quoted in this comment by the MMC is found on page 68. However, prior to the MMC quoted sentence, the NRC (2000) states: "For certain animal models it appears that TTS of 10 dB or less within 15 minutes after exposure is fully reversible and without obvious cochlear damage (Liberman and Dodds, 1987; Ahroon et al., 1996) as long as the exposures are not continued for long periods of time. In both studies, cochlear damage was evident only after TTS exceeded 40 to 60 dB within 15 minutes after exposure." NMFS believes that the NRC used this quoted statement to support the statements quoted by both the MMC and NMFS.

NMFS believes however, that the NRC is overly cautious in its choice of 10 dB of TTS as being a safe level. NMFS' review of Liberman and Dodds (1987) and Ahroon et al. (1996) does not support a level as low as 10 dB of TTS for being an upper level for prevention of PTS as suggested by the NRC (2000). Contrary, Ahroon et al. (1996) and Liberman and Dodds (1987) indicate that the difference between an initial TS that results in slight TTS (onset TTS) and the initial TS that results in slight PTS (onset PTS) is about 40-60 dB. In other words, from the lowest initial TS that recovers (i.e., TTS) to the level at which recovery is incomplete by several dB (i.e., PTS), the difference is routinely found to be 40-60 dB of TS. These values are found not only with longer duration stimulation, but with repeated application of impulsive stimuli as well (Ahroon et al., 1996). -

The problem of determining the same values for marine mammals with their marine-adapted ears remains to be solved. However, because the onset of PTS in marine mammals would be expected to be quite variable dependent upon the ear structure of the mammalian group (mysticetes, odontocetes, pinnipeds) and species-specific sensitivity, the health of the individual animal, and the characteristics of both the water and the acoustic source, there may not be a single value to establish for determining onset PTS. Therefore, in the absence of comparable data for marine mammals, NMFS believes it is precautionary to define the onset of PTS for marine mammals to be 20 dB of TTS. This level would be conservative for chinchillas, and would likely be conservative for marine mammals.

Comment PRC6: The HSUS continues to oppose the establishment of a received level of 180 dB (re 1 uPa (rms)) as the criterion (for low frequency, intermittent, or any other kind of sound) for onset TTS for all marine mammals. -

Response: NMFS agrees, noting that Ridgway et al. (1997) and Schlundt et al. (2000) found TTS significantly higher than 180 dB (re 1 uPa rms) in two odontocete species at intense one-sec. tones of 0.4, 3, 10, 20, and 75 kHz, while Kastak et al. (1999) documented TTS, for octave band noise with frequencies from 100 to 2,000 Hz, at mean values of 137, 150, and 148 dB (re 1 uPa) for the harbor seal, sea lion and elephant seal, respectively, for 20- to 22-minute exposures. (However, these data also have variations around the mean on the order of -5 to +10 dB.) As described in the account of the test, these levels can be considered to represent the lower level for onset of TTS for a 20-minute signal. NMFS clarifies that because TTS may result from a prolonged exposure to a faint sound, a brief exposure to a loud sound, or an intermediate exposure to a sound of intermediate loudness, sound duration and intensity can be considered to trade off with each other in causing TTS, as is indicated by comparing the work of Kastak et al. (1999) with the work of Schlundt et al. (2000). This is one reason why NMFS advises caution in the widespread advocation for the use of the 180 dB (re 1 uPa (rms)) standard for noise sources other than impulse noise. For the NPAL action, ONR/Scripps prudently presume that 95 percent of the marine mammals exposed to a "single-ping equivalent" (SPE) of 180 dB (re 1 uPa (rms)) could incur "harm" or TTS. NMFS believes that this is cautious as TTS is unlikely at an SPL of 180 dB since several species of cetaceans have the ability to vocalize at 180 dB and greater (see Richardson et al., 1995, Table 7.1). -

To account for the longer duration NPAL signal however, ONR and Scripps use the 180-dB SPE as the level for the onset of "harm" or TTS. An SPE is defined as the summation of the intensities for all received brief acoustic sounds into an equivalent exposure from one ping, which is always at a higher level than the highest individual ping received. In other words, an animal exposed to a single 1-minute ping at 180 dB could incur TTS, an animal exposed to 10 1- minute pings at 170 dB could incur TTS, and an animal exposed to 20 1-minute pings (the length of the standard NPAL signal) at 167 dB could incur TTS. This, NMFS believes, is precautionary and, notes that for the first time, a small take applicant has taken into account the duration of the signal when calculating impacts on marine mammals. -

Comment PRC7: The HSUS notes an inconsistency between the response to comment 5 and the response to comment 12 in the preamble to the proposed rule. In response 12, NMFS states "[T]here is no obvious connection between an annoying or harmful sound level for humans in air and an annoying or harmful sound level for a marine mammal in water." Either the human model is an appropriate one for marine mammals or it is not, NMFS cannot pick and choose which aspects of human hearing to consider as appropriate parallels with marine mammal hearing. -

Response: In the response to comment 12 which made allegations of neurological damage in humans at 140 dB (re 20 1 uPa), NMFS was quoting from the reference provided in the Federal Register document (Chapman and Ellis, 1998). The conclusion of the Chapman and Ellis (1998) article is that it would be unwise to assume that the auditory experience of any animal would be the same as that of humans exposed to the same sound level. In response to comment 5, NMFS noted that "while recognizing that no empirical data have been collected to establish this relationship, and there is no guarantee that marine mammal behavioral responses exhibit patterns similar to human hearing (emphasis added), the human model is the best objective foundation for an assessment and is consistent with Crocker (1997)." Reading both statements carefully indicates that they are not in disagreement. As scientific research on the effects of noise on marine mammals becomes available, the data from this research will be used by NMFS instead of using comparisons with human hearing. -

Comment PRC8: The MMC believes the rule should be revised in paragraph 216.177(a) to clarify whether an LOA will be issued annually or once, to cover a five-year period. -

Response: NMFS has clarified that the LOA will be issued annually. -

Marine Mammal Impact Concerns

Comment MMIC1: The HSUS continues to be disturbed by NMFS' apparently broad application of low frequency acoustic harassment standards-for impulsive, intermittent, and continuous sounds, both narrow and broad-band in character, for all marine mammals and sea turtles-on the very limited results from a U.S. Navy project using single, pure tones at various frequencies on a small sample of only two species of odontocete cetaceans (Ridgway et al., 1997; Schlundt et al., 2000). The HSUS repeats its objections, expressed in comments on the shock trial of the USS WINSTON S. CHURCHILL of applying the limited results from Schlundt et al. (2000) to all marine mammals. -

Response: While the small take authorization for the taking of marine mammals incidental to the use of the NPAL source by Scripps and ONR reference both Ridgway et al. (1997) and Schlundt et al. (2000) in its analysis for TTS impacts, it has not adopted the SPLs found by those authors for marine mammals incurring TTS. If it had, ONR/Scripps would have established the 95 percent risk value in the AIM at about 192 dB instead of the more precautionary 180 dB (see ONR, 2001 for an explanation of terminology). The previously referenced papers found that a masked TTS of 6 dB or larger, in bottlenose dolphins and beluga whales, occurred at between 192 and 201 dB (re 1 uPa (rms)) for intense one-sec. tones of 0.4, 3, 10, 20, and 75 kHz. However, the present action implements a TTS/harm zone at 180 dB, not 192 dB. An additional precaution provided by ONR/Scripps is through consideration of the 180-dB SPE, defined previously, to be "harm" or TTS. The 180-dB SPE is designed to take into account the longer duration of the NPAL signal (i.e., 20 min). -

However, because the Ridgway et al. (1997) and Schlundt et al. (2000) research were conducted in the region of greatest hearing sensitivity for bottlenose dolphins, it is believed that the levels identified for behavioral change and TTS at 3 kHz would be conservative for small odontocetes below 3 kHz (Ridgway S. pers. comm. as cited in ONR, 2001). Large odontocetes are considered as sensitive as mysticetes while pinnipeds are believed to be less sensitive than small odontocetes to underwater sound (ONR, 2001). Therefore, NMFS considers it very conservative to establish the threshold that 95 percent of the small odontocetes and pinnipeds, exposed to a single ping of LF sound at 180 dB could incur TTS. -

There are no studies of TTS and PTS in mysticetes. However, studies of human hearing indicate that the normal process of hearing loss with age (presbycusis) can be accelerated by chronic exposure to sounds 80 dB above the absolute threshold of hearing (Richardson et al., 1995). Here chronic is interpreted as about 8 hours/day for about 10 years. For odontocetes, Au et al. (1997) present data indicating that hearing thresholds are about 140 dB at 75 Hz. Hearing thresholds are not known in mysticetes, but the lowest value is speculated to be 80 dB (Ketten, 1998). This suggests therefore that 10 years of exposure to 160 dB RL for 8 hours per day would cause auditory damage. Therefore, estimating that 95 percent of mysticete and large odontocete whales will experience TTS after exposure to a 1-minute ping at 180 dB is also considered by NMFS to be conservative.

Comment MMIC2: The WDCS does not consider the level(s) for TTS found by Ridgway et al. (1997) to be conservative for the prediction for onset TTS in odontocetes or mysticetes in the wild. A report by Croll et al. (1999) states that baleen whales could suffer temporary auditory damage at noise levels as low as 120 dB and that physiological effects could occur well before 180 dB. -

Response: Please refer to the previous response. Although NMFS was unable to verify the statements directly to the Croll reference, the dB levels, quoted in the comment, apparently derive from Richardson et al. (1995) for effects on marine mammals extrapolated from human damage risk criteria (DRC) and from work done by Malme et al. (1983, 1984, 1988). For reasons explained previously in this document, one must consider duration of the signal and the type of noise (impulse or intermittent/continuous) before making generalities on impacts based solely on an SPL. NMFS believes that ONR/Scripps have addressed the duration issue by establishing the 180 dB SPE criterion. -

Comment MMIC3: The WDCS believes that repeated exposure could lead to at least gradual hearing loss and PTS. Ketten (1998) stated: "It has been established that repeated exposures to TTS-level stimuli without adequate recovery periods can induce permanent, acute threshold shifts." Also, the MMC notes that as it is known that repeated exposure of terrestrial mammals to sounds capable of causing TTS increases the likelihood of PTS, there is the possibility that repeated exposure to sounds capable of causing TTS increases the likelihood that marine mammals would be injured.

Response: While there is some recent research indicating that there is no relationship between repeated TTS exposures and an animal incurring a PTS injury, the science to date indicates that PTS can occur with repeated exposures of TTS without allowing animals to completely recover, as stated by Ketten (1998). However, noting the behavior of marine mammals in the NPAL area, especially the migratory behavior of humpback whales and that the NPAL source is in a water depth that would prevent marine mammals from incurring a TTS impairment, a PTS injury is unlikely to occur. NMFS believes the SPLs in those areas of the water column that marine mammals inhabit are simply too low to cause TTS, let alone PTS. -

In response to comment PRC6, NMFS concurred with ONR that a marine mammal exposed to 20 1-minute pings (the length of the standard NPAL signal) at 167 dB could incur TTS, or Level B harassment. The 167-dB isopleth is only 25 m (82 ft) around the NPAL source at its 807 m (2,648 ft) depth, meaning that a marine mammal would need to dive to a minimum depth of 782 m (2,565 ft) and remain within that small area for the entire 20-min transmission in order to theoretically incur a TTS impairment. Theoretically then, the marine mammal would need to do this dive repeatedly, time after time, year after year, to incur a PTS injury from the NPAL source. Therefore, NMFS believes that, considering the migratory behavior and transitory nature of those marine mammal species likely to be impacted, and other reasons including dive profiles, it would be very unlikely a marine mammal would incur a TTS impairment and virtually impossible for a marine mammal to incur a PTS injury from the NPAL source. -

Comment MMIC4: The MMC agrees with NMFS that defining TTS as Level B harassment is reasonable only if the TTS does not make the affected animals vulnerable to predation or otherwise affect their survival or productivity. In this regard, the MMC notes that it is not inconceivable that temporary hearing impairment over a period of one to a few days could increase the potential for injury or death of an affected animal, e.g., by increasing vulnerability to natural predation or ship strike. If such were the case, TTS would have the potential for injury and would constitute Level A harassment. -

Response: First, in order for a marine mammal to incur TTS from the NPAL source, it would need to dive to water depths deeper than scientific knowledge indicates that humpback whales are capable of diving. Sperm whales and beaked whales, while capable of diving to those depths, are not expected to occur in the immediate vicinity of the source in any numbers, nor likely coincide a dive to those depths during the brief 2 percent (or 8 percent for non-migratory marine mammals) duty cycle of the NPAL source. For those marine mammal species capable of hearing the NPAL sound, TTS is unlikely considering the depth of the 167-dB isopleth (based on a SPE of 180 dB for the full 20 minutes) and the short duty cycle. For those marine mammal species unable to hear the NPAL source (75 Hz) well, TTS is simply not possible. For a response on considering all, or a portion of Level B harassment takings as Level A takings, please refer to the response to comment MMPAC1. -

Second, NMFS does not agree that affecting a marine mammal's survival or future productivity would require a taking to rise to Level A harassment (injury), unless the activity directly affected in some injurious way, either the mammal's ability to reproduce, or it's newborn or unborn offspring. To the extent possible, what NMFS is evaluating under Level B harassment is the lost opportunity to mate, primarily as demonstrated by using the AIM. -

Comment MMIC5: The HSUS continues to oppose NMFS rejection of the use of the preliminary results of the investigation into the March 2000 stranding of various cetacean species in the Bahamas, as cited in the MMPA Bulletin, yet NMFS applies its management decisions on the results from Schlundt et al. (2000) and the Low Frequency Active Scientific Research Program (LFA SRP) associated with the Navy's NEPA process for SURTASS LFA sonar. -

Response: NMFS does not reject the preliminary findings of its joint investigation with the Navy on the Bahamian multi-species stranding, only the relevancy of the preliminary findings in the context of this rulemaking. Issue 19/20 of the MMPA Bulletin noted that "the injuries to the five beaked whales were all consistent with an intense acoustic or pressure event. All five beaked whales showed some evidence of trauma to tissue associated with hearing, sound production, and/or airways. In particular, all had some hemorrhages in or around the ears. Other tissues related to sound conduction, or production such as the larynx and auditory fats, had minor to severe hemorrhages. The injuries revealed in the necropsies were not consistent with a nearby explosion (there were no bone fractures), but could have been caused by a distant explosion, or an intense acoustic event. Postcranial tissues showed minor lesions in heart muscle and minor hemorrhage in lung and kidney tissue that are less indicative of cause than the skull damage. In humans, injuries such as these would have caused extreme discomfort, but do not generally cause permanent hearing loss or death. Essentially, these animals died from actually stranding on the beach." This means that loud, intense sounds can cause injuries to marine mammals that are in the vicinity of loud, high intensity sound sources. A sound source such as NPAL's source is simply not of sufficient intensity to cause the impacts described in this response. That is the reason NMFS does not consider the Bahamian stranding incident relevant to a discussion of potential impacts by the NPAL source. Because the NPAL source is moored in 807 m (2,648 ft) water depth, and because this depth is approximately 550 m (1,804 ft) deeper than the deepest recorded humpback whale dive depth (the only deep-diving marine mammal species expected to be commonly found in the offshore NPAL waters), NMFS restricts its discussion of impacts to behavioral responses (Level B harassment), and not injury (Level A harassment) or mortality to marine mammals from the NPAL source. As a result, NMFS has incorporated into its determination the scientific findings of the California and Hawaii ATOC Marine Mammal Research Program (MMRP), and secondarily the scientific findings of the LFA SRP. Utilization of the findings of Schlundt et al. (2000) have been discussed previously in this document. -

Comment MMIC6: The MMC requests NMFS provide the basis for the statement that a received level of 120 dB is presumed to have a zero potential for disturbing biologically important behavior of humpback whales. Apparently, both bowhead and beluga whales have shown strong avoidance reactions at or below a received level of 120 dB, and some of the clearest individual cessations of humpback whale song to the Navy's LFA source have occurred at received levels of only 122 dB. -

Response: As stated in ONR's final EIS, and adopted by reference by NMFS, science cannot establish zero risk. Therefore, the AIM cannot establish zero risk. However, given the shape of the risk function, 120 dB can be established as the point at which risk is so low, that it is pointless to calculate the risk below it. Changing this basement value for risk by as much as +10 dB (110-130 dB) would not affect the number of potential takings and would not alter the cumulative risk values. For humpback whales, the marine mammal most likely to be impacted by the NPAL source, some singers stopped singing and showed avoidance reactions at levels near 120 dB (re 1 uPa (rms)), while other singers continued singing when exposed to playbacks at levels as high as 150 dB (re 1 uPa (rms)). This, according to Clark et al. (1999), may be due to individual differences between singers. Observers had the distinct impression, often even before a LFA playback began, that certain singers had very stable behavioral patterns and were imperturbable whereas other singers were much more variable and responsive even to the vessel approach. This may represent two different types of singers, dominant and experienced singers, and younger, less experienced, singers. If these younger, less experienced singers are nondominant males, unlikely to successfully mate, this behavior would not be unexpected if the SURTASS LFA sonar transmitting waveforms similar to humpback whale songs at the same time. -

While bowheads and belugas have been shown to have a behavioral reaction to received SPLs at or below 120 dB, NMFS would not characterize the avoidance reactions as being strong. For bowhead whales at least, it has been necessary to apply strong statistical analyses in order to determine that bowheads in the Beaufort Sea north of Alaska reacted to seismic pulses at distances where received levels were on the order of 120 dB. Richardson et al. (1995), summarizing the information available at that time, noted that initial behavioral changes were detected when received noise levels were 142-157 dB (re 1 uPa (rms)); active avoidance became evident at SPLs of 152-178 dB. More recently, bowheads have been detected, through statistical analyses, making minor course corrections at lower SPL levels, however, these course corrections were not detectable visually from aircraft. NMFS has clarified several times that behavioral reactions appear to be context related, such as gray whales reacting to industrial noise when the source is located in its migration path, but showing greatly reduced responses when the acoustic source was located offshore of the migration path (Clark et al., 1999). In the case cited by the MMC, bowheads and belugas inhabit waters frequented by ice and may require a low ambient noise level in order to navigate successfully through the ice, to locate leads and polynyas, and avoid ice keels. This type of environment is not found in Hawaii.

Comment MMIC7: The MMC recommends that the rationale should be provided for Scripps' determination that "only humpback whales that remain in the vicinity of the source for a full day of transmissions may potentially experience any effect from the source transmissions."

Response: The rationale relates to how the modeling was carried out. ONR/Scripps conducted the AIM under two conditions - one in which the animals were only exposed to one 20-min transmission, and another in which the animals were exposed to six 20-min transmissions (that is, a full day of transmissions). In both cases, ONR/Scripps modeled a milling movement pattern that kept the animals in the general vicinity of the sound source, rather than the movement pattern that was observed from the shore stations where the animals moved parallel to the coast (and thus would not remain in the general vicinity of the sound source for very long). Only for humpback whales under the second scenario (milling in the vicinity of the sound source for a full day of transmissions) was there a chance for humpback whales to experience a biologically important reaction to the sound source (see Table 4.2-5 in the ONR final EIS). The details of the modeling are described on p. 4-17 of the ONR final EIS.

Comment MMIC8: The WDCS noted that while the studies noted in the NMFS' ANPR reported no significant changes in the abundance of humpback and sperm whales, Calambokidis et al. (1998) found that humpbacks and sperm whales were generally seen farther from the sound source during experimental versus control surveys.

Response: While NMFS concurs with the WDCS' synopsis of the work by Calambokidis et al. (1998) during ATOC studies off Pioneer Seamount, NMFS does not equate a shift in local distribution of humpback whales with a change in abundance near the NPAL source. NMFS hopes that the findings by these scientists will soon be published and become available. NMFS understands that humpback and sperm whales were displaced approximately 0.6 km (0.3 nm, 1,823 ft) between times when the source was on and when it was off. However, NMFS notes that this displacement was noted by later statistical analysis and was not apparent to the observers. The findings of Calambokidis et al. (1998) are consistent with the findings of Frankel and Clark (1998, 2000). Frankel and Clark (2000) found that humpback whales within 12 km (6.5 nm) of the source showed only subtle, short-term effects on their surface behaviors. The whales did not show any immediately obvious response to the ATOC signal at received levels less than 130 dB and they did not abandon their coastal habitat adjacent to the offshore ATOC source. Frankel and Clark (2000) concluded that the present operation of the ATOC source off Kauai is not sufficient to cause biologically significant changes in behavior for the humpback whale population wintering off Hawaii, but that this conclusion cannot be generalized to the effects of cumulative impacts from other anthropogenic sources of noise in the marine environment. Essentially this is the reason for ONR/Scripps requesting a five-year small take authorization and having a monitoring program to better assess potential long-term cumulative impacts.

Comment MMIC9: The MMC notes that the list of deep-diving species of marine mammals commonly found off Kauai in response to comment 12 of the proposed rule document should be revised to include sperm whales, another deep- diving marine mammal commonly found in the referenced offshore waters.

Response: While sperm whales are found in the offshore waters of Kauai and are included in the list of species expected to be taken by harassment, information available to NMFS does not indicate that this species is commonly found in the area of NPAL operations. This is explained in the proposed rule and in ONR's draft EIS, and clarified in the response to the following comment.

Comment MMIC10: The MMC notes that the statement that no statistically significant shifts in distribution were found for species other than humpback whales (and possibly sperm whales) does not diminish the fact that shifts in distribution were observed, especially since these two species have the ability to detect, and are more likely to occur at depths where they would be exposed to, the sound source. NMFS should more clearly explain the basis for the belief that sperm whale distributions may have been affected and should also include information on such confounding factors as small sample sizes etc.

Response: Shifts in sperm whale distribution were not observed at the Kauai site due to small sample sizes. However, shifts in distribution were observed at the ATOC site at Pioneer Seamount, off California, and, therefore, can be presumed to occur at Kauai. NMFS notes that few sperm whales (about 100) were detected during the Hawaii-wide aerial surveys from 1993 to 1998 that detected 2,773 humpback whales. Although some sperm whales may have been missed because they were diving at the time of the survey, these numbers provide support that sperm whales are more than an order of magnitude less abundant than humpback whales off Hawaii. Also, while the avoidance was statistically significant in California, the actual distance of displacement was small. Therefore, NMFS agrees that sperm whales could be affected if they were in the vicinity of the source during the 2 percent time that the source is on. However, there is no evidence on record to indicate that sperm whales are seasonal residents offshore of Kauai, and thus no individual animal is expected to receive more than a single transmission. Based on this information, NMFS believes that no more than a few sperm whales may pass through the NPAL source's zone of influence during the year when the source is on, and may have a minor avoidance reaction to the NPAL source.

Comment MMIC11: The WDCS asks whether the statement that "no significant shifts in distribution were found for any other species of marine mammal" is valid because these other species were not the focus species of the survey or because the sample size was not large enough? -

Response: As stated in ONR's draft EIS, only humpback whales were seen in sufficient numbers (i.e., large enough sample size) around the Kauai site to permit quantitative assessments of distributional changes from 1994 (source off) to 1998 (source on).

Comment MMIC12: The MMC believes the statement that humpback whales in Hawaii show an "almost statistically significant increase in population size", is not convincing support for maintaining that the observed shift should not be considered important. The MMC believes that given the ambiguities associated with the data, it is particularly important that the monitoring program be designed to detect possible longer term biologically significant changes that may be produced by the sound source.

Response: The monitoring program has been designed to detect long-term changes in the distribution and abundance of humpback whales and is discussed later in this document.

Comment MMIC13: Although the WDCS possibly agrees with NMFS that the best scientific information to date is provided by the ATOC MMRP and the SURTASS LFA SRP, these are still not complete studies. WDCS understands that the final analysis is not available from the LFA SRP.

Response: The final analyses for the SURTASS LFA sonar SRP are found in the Technical Report # 1 (Clark et al., 1999). Some of this research remains under peer review prior to publication in scientific journals. Other research has already been published (Miller et al., 2000). Scientific research under the ATOC MMRP includes Frankel and Clark (1998, 2000).

Comment MMIC14: The WDCS, noting that both sperm and beaked whales are known to be deep divers and that sperm whales were shown to be affected by previous ATOC experiments, asks again whether research has been conducted on the depths that these animals reach around the proposed NPAL area.

Response: Research on the diving depths of sperm whales and beaked whales in the waters offshore of Kauai is not practical due to the low abundance of these species in these waters. Research on depth of dive for these species in other areas indicates that they are capable of diving to the depth of the NPAL source. This was described in ONR's draft and final EISs.

Comment MMIC15: One citizen noted that he does not know what acoustic devices the Allied forces may have employed around the time of the strandings, but we do know that LFAS was scheduled to operate in the region a short time earlier. One large balaenopterid live-stranded following that scheduled deployment, and it should be further investigated for evidence of trauma.

Response: NMFS presumes the commenter is referring to the multi-species stranding event in the Bahamas on March 16, 2000. The single minke whale that stranded during this event was released off the beach alive. Therefore, a necropsy was not conducted on that animal. Also, NMFS is unaware of what "LFAS" operation the commenter is referring; however, NMFS understands that no LFA sonar operations were conducted during the referenced time period.

Comment MMIC16: One citizen pointed out that the evidence of hemorrhage in acoustic fats and tissues adjacent to the ears, and in the brain (Rowles et al., 2000) are not strictly speaking, auditory traumas. They are barotraumas, for which determination of TTS or PTS levels, and the assumed "safe" level of 180 dB RL are irrelevant. The commenter states he has investigated the information available on the Bahamas and 1996 Greek strandings (D'Amico (ed), 1998). He has calculated that damage to the tissues probably occurred in the range of 143-157 dB RL of the offending acoustic energy. This damage could be exacerbated by resonance phenomena, such as that reported in the Navy's 1999 Technical Report #3, in concert with the enormous pressure at the normal diving depths for beaked whales (500-1500 m (1,640-4,921 ft)).

Response: As NMFS has not been provided with any scientific information by the commenter to support his calculations that tissue damage could occur in the range of 143-157 dB RL, NMFS cannot respond further on this statement. NMFS notes however, that in order to incur an SPL of 143 dB, an animal would need to dive to a depth of at least 400 m (1,312 ft) during the 2 percent time that the NPAL source is active, and not react to the source transmissions during ramp-up.

Comment MMIC17: If resonance phenomena are implicated in tissue damage observed in the beaked whales, it should be noted that the resonant frequency of airspace in Ziphius cavirostris is reported to be 75 Hz at 100 m (328 ft) depth (derived from D'Amico, 1998), which happens to be the center ATOC frequency. Theoretically, beaked whales could be damaged somewhere between 100 m (328 ft) and many kilometers from the source depending upon the signal and the propagation characteristics.

Response: NMFS is charged by the MMPA to make negligible impact determination based upon the best scientific information available. As the commenter has not provided any scientific information to support his hypothesis, NMFS cannot respond further on this statement. However, NMFS would appreciate this information at the commenter's earliest opportunity.

Comment MMIC18: The HSUS urges NMFS to consider the potential impact of loud, low frequency sound on other physiological processes and body organs of marine mammals. There is a growing body of literature that suggests such impacts can have long-term debilitating effects, at least in terrestrial species.

Response: To NMFS' knowledge, other than pacinian corpuscles, which are believed to be sensitive to vibration, the only other physiological impacts to marine mammals would be due to high intensity sources that might impact marine mammal lungs or the fat pad sound channel (which conducts sounds to the middle ear) in the lower jaw of certain odontocetes. However, the NPAL source with a maximum SPL of 195 dB (re 1 uPa (rms)) has neither sufficient intensity nor rise time to cause this type of injury.

Mitigation Concerns

Comment MC1: The HSUS, while agreeing that ramp-up should be incorporated as a mitigation measure even if there is no evidence that it is effective, believes that calling ramp-up precautionary is inappropriate. If ramp-up is not effective, the animals will potentially suffer for it. The MMC believes that it is reasonable to assume that most marine mammals will move away from the sound source as it is ramped up. However, studies necessary to validate this assumption have not yet been done.

Response: As noted in response to comment 17 in the proposed rule, NMFS recognizes that ramp-up may not be effective as a mitigation tool. However, ramp-up has been recommended to be employed in offshore seismic activities by the participants at the High-Energy Seismic Survey (HESS) panel. Moreover, based on observational data showing that humpback and sperm whales actively avoid noise from the NPAL source, ramp-up should be at least partially effective as a mitigation measure for the NPAL activity.

Comment MC2: One citizen noted that the AIM referred to for mitigation is theoretically elegant, but woefully inadequate zoogeographically (Navy, 1999 SURTASS LFA Sonar Technical Report 2). The species abundance and distribution for cetaceans modeled for LFA sonar around the Bahamas (site 29) were obviously erroneous, and it appears likewise for areas around Hawaii (sites #6 and #12).

Response: The AIM is a model used to estimate the levels of taking of marine mammals by harassment; it is not a mitigation measure. The ONR draft and final EISs on NPAL explain in detail the inputs into the AIM for the location of the NPAL source. When information becomes available to the Navy the AIM can be, and will be, improved. For the NPAL action, however, NMFS concludes that the information contained in the ONR draft and final EISs and the Scripps' small take application contain the best scientific information available on the subject, since additional information has not been provided to it, or the Navy.

Comment MC3: The MMC believes that the mitigation measures should specify that the sound source will operate on a duty cycle of 2 percent and a power level no greater than 230 watts. The MMC also believes the authorization would appear to authorize transmissions exceeding 195 dB.

Response: Both of these recommendations have been addressed as alternatives in ONR's draft and final EISs. The proposed action by Scripps and ONR is to operate the NPAL source on a duty cycle an average of 2 percent during the period February through April with any increases in the duty cycle beyond the nominal 2 percent (with a maximum of 8 percent) not occurring during the humpback whale season (January-April). The 2-percent duty cycle does not include the ramp-up period. However, there is no evidence in the record to support the MMC's recommendation to limit the transmissions to 2 percent year- round. For reasons detailed in the ONR draft EIS, there are valid scientific reasons for needing to exceed a 2 percent duty cycle at certain times of the year.

Also, there is no evidence in the record to support limiting the NPAL power source to 230 Watts, as opposed to the stated operating power of 260 Watts. The NPAL sound source has been designed to operate at the minimum power level necessary to support large-scale acoustic thermometry and long-range sound transmission objectives. It should be recognized that signal length and power trade off with each other; a shorter signal length would require increased power to accomplish the project's objectives. Mitigation measures are also described under "Mitigation" in the preamble to both the proposed rule, and this document.

Monitoring and Reporting Concerns

Comment MRC1: The MMC believes that, if NMFS has concluded that long-term monitoring studies are necessary only if the project's duration extends beyond 5 years, NMFS should explain why it believes that such long-term monitoring studies to identify the potential cumulative impacts of the currently proposed 5-year program are not currently warranted. The WDCS, while concurring with NMFS' statement (in response to comment 1 in the ANPR) that long-term studies should be initiated if the project were to continue beyond 5 years, believes such monitoring should start now, not after the program has been in operation for more than 10 years.

Response: NMFS clarifies that it considers the aerial monitoring program that was conducted between 1993 and 1998 off the north shore of Kauai as part of the ATOC MMRP to be part of a long-term monitoring program. Data were collected during the humpback whale winter breeding season (February- April) for a total of 3 baseline years when the Kauai ATOC source was not transmitting (1993, 1994 and 1995) and for 1 year when it was transmitting (1998). An additional year of baseline surveys (source off) were conducted in the area off the north shore of Kauai during the 2001 humpback breeding season. The earlier years' information is summarized in Mobley et al. (1999), which will be available upon request from NMFS, until formal publication. With 5 years of data, NMFS believes that continuing this monitoring program during the next 5 years (when the source is expected to be on) will provide NMFS and others with information on long term trends. NMFS believes that the aerial monitoring program described in this document provides the best practical method for assessing long term effects of the NPAL source.

Comment MRC2: The MMC believes that available data are insufficient to conclude with confidence that there will be no long-term effects on distribution, size, or productivity of any of the potentially affected marine mammal stocks. Given that there is uncertainty as to whether the taking could have biologically significant long-term effects, the MMC considers it essential that Scripps' monitoring program be designed to enable NMFS to detect any such possible project-related changes. The MMC, therefore, recommends NMFS consult with Scripps and scientists familiar with the demography and behavior of marine mammals that could be affected by the proposed action to determine the baseline information and kinds of monitoring that would be required to detect possible long-term population-level effects.

Response: See response to comment MRC1. NMFS has determined that the long- term monitoring program designed by Scripps will adequately assess impacts to humpback whales during the 5-year authorization for NPAL takings. The evidence from various sources, contained in this document and in the Scripps/ONR final EIS, indicate that marine mammal species, other than humpback whales and possibly sperm whales, would be unaffected by the LF, low intensity source because of either distributional, water column preference, and/or hearing abilities for LF sounds. Therefore, NMFS believes it is most important to focus monitoring efforts on humpback whales (although other marine mammal species will also be assessed during humpback whale surveys). -

Comment MRC3: The MMC recommends that NMFS, if it issues the LOA, include a description of the required monitoring program, in sufficient detail to enable reviewers to judge the likelihood that it will be capable of detecting biologically significant long-term effects in time to stop and reverse them. -

Response: NMFS has expanded the discussion on the monitoring program in this document. For additional information on the protocols that will be employed, please refer to Mobley et al. (1999) which is available upon request. Their analysis included both calculating distance from shore and distance from source to assess distributional shifts. They also calculated an incidence rate that is comparable between years since the survey tracklines were constructed using the same rules. Therefore, although an overall abundance estimate cannot be estimated from these surveys, a relative incidence rate among years can be estimated. -

Comment MRC4: The MMC notes that NMFS did not respond to the MMC's recommendations (in its letter to Scripps dated 22 September 2000) that (1) scientists with broad knowledge of the form and function of cetacean vocalizations be consulted to determine whether monitoring and comparing vocalizations before, during, and after NPAL transmissions could help resolve the uncertainties concerning masking and possible behavioral disruptions and (2) if the consultations indicate that such monitoring would be possible and useful, an appropriate vocalization monitoring program be designed and included as part of the proposed action. -

Response: The potential for masking and masking effects were studied during the Kauai ATOC MMRP and summarized in ONR's draft and final EISs. The Kauai ATOC MMRP did not find any overt or obvious short-term changes in singing behavior of humpback whales in the vicinity of the sound source. In addition, no statistically significant changes in the underwater sound output from humpback whales in one of the frequency bands in which they vocalize was found in the vicinity of the Kauai source. Therefore, it is estimated that the potential for effects from masking would be minimal and limited to no more than 2 percent of the time for those animals in residence off the north shore of Kauai. Therefore, NMFS has determined that no additional short-term studies on masking effects associated with the NPAL source are required, especially since this research would need to be conducted at the cost of decreased coverage in the long-term aerial monitoring program. -

Comment MRC5: The WDCS, while pleased that 8 aerial surveys will be conducted each year, rather than 4 surveys, is concerned that no surveys will be conducted when the duty cycle may be increased to 8 percent. -

Response: As explained elsewhere in this document, under authorized funding levels for this project, conducting additional surveys outside the humpback whale season would necessitate a reduced aerial survey effort for humpback whales during the humpback whale season. Because the required humpback whale aerial surveys will also detect other marine mammal species, NMFS believes that additional aerial surveys are not an efficient use of NPAL's limited resources and, because this additional monitoring is unlikely to provide NMFS and the public with better data than would be provided during the humpback whale aerial surveys, should not be required. -

Because the smaller whales and dolphins are not expected to be sensitive (e.g., react) to the Kauai NPAL acoustic source transmission, and because the required humpback whale aerial surveys will also detect other marine mammal species, NMFS also does not believe that conducting boat-based surveys for these species is warranted. -

Comment MRC6: The WDCS does not believe that the proposal to coordinate and investigate stranding events will lead to a responsible indication of the number of cetacean deaths that may occur as a result of NPAL operations. The WDCS believes that a small number of cetaceans that die at sea (will) then wash ashore to be found. -

Response: As explained in detail elsewhere in this document, due to the water depth of the NPAL source and the fact that it is not of sufficient intensity to result in hearing damage, NMFS has no scientific reason to suspect that the NPAL source could result in injury or death to marine mammals through either hearing or other body function impairments. However, Scripps will be required to coordinate with the Hawaiian Islands' marine mammal stranding network to ensure that all strandings are investigated and analyzed to the extent possible. Moreover, marine mammals do not need to be onshore in order to be considered a stranding. Therefore, floating dead marine mammals spotted during marine mammal aerial surveys will also be investigated by Scripps and the stranding network to the extent possible. -

Comment MRC7: The MMC notes that the discussion of the aerial survey monitoring program does not, but should, describe by whom the aerial surveys would be conducted, what area or areas would be surveyed, what data would be collected, and, what would be considered biologically significant effects, and should describe the kind of changes in distribution and abundance that would trigger a review and suspension or termination of the project. -

Response: NMFS agrees. A more complete description of the monitoring program protocols can be found in this document. -

Comment MRC8: The MMC notes two things in regard to the following sentence found in the preamble to the proposed rule: "Based on an average of seven humpback sightings per survey observed during the 1998 season and assuming a moderate-sized effect due to NPAL transmissions, eight surveys should produce a minimum of 56 sightings of humpback whales, which would result in an estimated power of 0.80 (i.e., there would be an 80-percent probability of detecting a change in distribution if an effect is present)." First, that while the term "moderate-sized effect," found in discussion of the ability to monitor effects on humpback whales, is a standard statistical expression in estimating power, NMFS should indicate what it understands to be "moderate-sized" with respect to humpback abundance near the source. Second, NMFS should include a reference to size as well as distribution. -

Response: Previous studies (Calambokidis, 1998) showed the mean distance from the ATOC source to be a relatively sensitive metric for assessing distributional changes of whales. However, no significant changes were noted for incidence (numbers) of whales in the "on" vs "off" experimental phases. Frankel and Clark (1998, 2000) also showed a similar effect in terms of distributional-related behaviors (i.e., distance and duration between surfacings). So the issue of statistical power was only applied to the distance from source variable, based on a difference on the order of 10 percent or greater. Though Scripps will report any differences in incidence, it is not expecting that metric to be particularly useful for later analysis, so the issue of power is not relevant there. In regard to the MMC's second point, it is not appropriate to calculate humpback whale abundance with the aerial survey design. However, since the aerial survey tracklines will be constructed using the same rules as the baseline data surveys, it is possible to calculate a rate of incidence that is comparable between years. Therefore, although an overall abundance estimate cannot be estimated from these surveys, a relative incidence rate among years can be estimated. -

Comment MRC9: The MMC asks what is meant by "an acute or short-term effect" on marine mammals that would trigger suspension of source operation and contacting NMFS. Also, what criteria would be used to determine whether the NPAL source was responsible for a stranding event. -

Response: The Marine Mammal Monitoring and Studies Program would continue to monitor for acute, short-term effects, even though none were observed during the ATOC MMRP. Acute or short-term effects are defined as: (1) Animal dead or disabled (primary capability), (2) Increase in number of beached animals (potential/limited capability), (3) Increase in number of animals struck by vessels (potential/limited capability); (4) Repeated/prolonged activity (blowing, time on surface, etc.)(potential/limited capability), (5) Abnormal number of animals present/absent (primary capability), (6) Abnormal mother-calf activity (potential/limited capability). If at any time a Marine Mammal Monitoring and Studies Program team member positively identifies the occurrence of an acute or short-term effect, the information would be immediately communicated to the Marine Mammal Monitoring and Studies leader (Dr. J.Mobley, University of Hawaii). If the leader ascertains that an acoustic transmission (i.e., during the 5-min ramp-up or the 20-min transmission) coincided with the observed effect, he would contact the Barking Sands shore termination site and Scripps, and suspend source operations immediately until further notice by NMFS. The leader would collate all pertinent information relative to the incident and contact NMFS to inform them of the situation. NMFS, in consultation with the leader, would make the determination as to the severity of the situation, based upon the knowledge of the species type, the animal's location relative to the source, the source level at the time of the incident, the estimated received level at the animal, whether there were any other noise sources in the vicinity, etc. Based upon analysis of the information supplied, NMFS would recommend that one of the following options be executed: (1) Continue experiment as planned, (2) Continue experiment with modifications to maximum source level or duty cycle, or (3) Suspend experiment pending consultation with NMFS. Regardless of the decision, within 24 hours, a written summary of the incident would be forwarded to ONR, Scripps, and NMFS. -

If a dead or disabled animal is observed during the visual aerial surveys, this information would be provided to the Kauai stranding coordinator, who would follow his/her agency's protocols for handling of a dead or disabled animal. -

Comment MRC10: The MMC questions the apparent discrepancy between NMFS statements that the 8 aerial surveys have an 80 percent chance of detecting a change in distribution (or abundance around the source) with the statement that the level of data from the monitoring program would not allow determinations to be made that the NPAL source was responsible for any decreases in abundance of humpback whales or other marine mammals in the vicinity of the source. The MMC believes that a monitoring program under a incidental taking authorization must be capable of detecting possible, non-negligible, project-related changes in distribution, abundance, or productivity of marine mammals. -

Response: The MMC quoted the sentence out of context. The entire statement from the proposed rule reads:

NMFS does not believe that the level of data from the monitoring program will allow determinations to be made that the NPAL acoustic source was responsible for any decreases in abundance of humpback whales or other marine mammals in the vicinity of the source. At this time, evidence indicates that the numbers of humpback whales and Hawaiian monk seals off Kauai are increasing, however, it is unclear whether this is due to total abundance increases or geographic shifts due to oceanographic changes. Similarly, a cause and effect between operation of the NPAL source and any decrease in abundance of marine mammals in the offshore Hawaiian Islands over the short-term period of 5 years is unlikely.

The aerial monitoring program is designed to detect a change in distribution and abundance of humpback whales in the vicinity of the NPAL source due to the source being on at the time of overflight versus the acoustic source being off. This will be done by "distance from shore" analyses. The aerial monitoring program will not detect changes in distribution for other marine mammals because the numbers of animals detected will be too low. However, the best scientific information indicates that these other species will not be affected by the NPAL acoustic source. -

NMFS believes that the NPAL monitoring program has been designed to conform to the greatest extent practicable with the guidelines found in the MMC's monitoring paper by Swartz and Hofman (1991). By using the information collected over the past five years, along with information collected by the aerial monitoring program north of Kauai and the Hawaii-wide aerial surveys, NMFS believes that determinations in trends in abundance for humpback whales will be attainable. -

Comment MRC11: The MMC recommends that the final rule should contain a specific date by which annual reports under the LOA are to be submitted. -

Response: A date for receipt of an annual report under a LOA is a condition for an LOA, not rulemaking. This allows NMFS the ability to modify the timing for the annual report, if necessary, without the need to undertake lengthy rulemaking. However, renewal of an LOA is conditional upon receipt of an annual report that is acceptable to NMFS. -

NEPA, ESA and Other Concerns

Comment NEC1: The WDCS, while pleased that the ONR and Scripps will include a discussion on Hawaiian monk seals in the final EIS and in the AIM calculations, is nevertheless dissatisfied considering the endangered status of the monk seal that data were not made available at the time of the writing of the draft EIS. -

Response: A draft EIS is, as its title suggests, a draft document. When information is lacking, incomplete or inaccurate, corrections are made in the final EIS, if noted by commenters and provided the information in the draft EIS is not so inadequate to preclude meaningful analysis (40 CFR 1502.9(a)). Information was provided in the draft EIS on the status of the monk seal in one of the NEPA alternatives, that is, use of the NPAL source at Midway Island. Recent information (Forney et al., 1999) indicates that the monk seal population at the Main Hawaiian Islands (MHI) is approximately 40 animals which includes the 21 animals relocated to the MHI from Laysan Island in 1994. More recently, in August 2000, NMFS conducted a statewide aerial survey which observed 17 beached seals in Kauai County and 3 births which were all on the island of Kauai. To account for animals that may not have been observed for a reasonable estimate of the actual population size, NMFS normally multiplies the beach counts by a correction factor of 3. This recent information has been included in the ONR's final EIS. However, as stated previously, NMFS does not believe that Hawaiian monk seals will be impacted by the NPAL source considering that monk seals are believed to be mid-frequency-specialist hearers, the relatively low SPL of the NPAL source at the water surface in the offshore vicinity of the source (less than 136 dB), and the coastal nature of the Hawaiian monk seal, where SPLs will be even lower. -

Comment NEC2: The MMC notes that a reference was not provided with the statement that Hawaiian monk seals are "high-frequency" (HF) specialists. Also countering NMFS' statement that the Agency did not believe that monk seals would be impacted by the NPAL source, the MMC is unaware of studies on monk seal hearing, at-sea movements, diving behavior and behavioral responses to LF sound. The MMC believes that without additional analyses, installation and operation of a sound source at the Midway location would be contrary to the provisions of the ESA and NEPA and the regulations should not authorize operation of the NPAL acoustic source in the Midway Island area until such information is available. -

Response: The reference for monk seals being HF specialists is Thomas et al. (1990). These authors found auditory thresholds for monk seals from 2 to 48 kHz, with best sensitivity between 12 and 28 kHz. For marine mammals, this best-sensitivity range means that monk seals are considered mid-frequency specialists, not HF specialists. Nonetheless, this continues to support NMFS' belief that monk seals are unlikely to be affected by a LF source such as NPAL, which transmits at 75 Hz (.075 kHz). -

It is not clear to NMFS how locating the source at Midway would be contrary to NEPA and the ESA. The draft and final EISs prepared for this action by ONR describe the impacts of locating the source at either Kauai or Midway. The Council on Environmental Quality regulations implementing NEPA (40 CFR 1502.22) addressed the issue of proceeding with incomplete or inadequate information. -

In addition, NMFS has completed consultation under section 7 of the ESA on conducting the activity off Kauai. If Scripps and ONR decided to relocate the activity to Midway, then ONR would need to reinitiate consultation under section 7 of the ESA. In addition, because this small take rule has now been finalized, a new rule would need to be proposed in order for a small