[Federal Register Volume 71, Number 130 (Friday, July 7, 2006)]
[Notices]
[Pages 38710-38738]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 06-6050]



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Part III





Department of Commerce





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National Oceanic and Atmospheric Administration



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Small Takes of Marine Mammals Incidental to Specified Activities; Rim 
of the Pacific Antisubmarine Warfare Exercise Training Events Within 
the Hawaiian Islands Operating Area; Notice

  Federal Register / Vol. 71, No. 130 / Friday, July 7, 2006 / 
Notices  

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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

I.D. 062806A


Small Takes of Marine Mammals Incidental to Specified Activities; 
Rim of the Pacific Antisubmarine Warfare Exercise Training Events 
Within the Hawaiian Islands Operating Area

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

ACTION: Notice; issuance of IHA.

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SUMMARY: In accordance with the provisions of the Marine Mammal 
Protection Act (MMPA) as amended, notification is hereby given that 
NMFS has issued an Incidental Harassment Authorization (IHA) to the 
U.S. Navy (Navy) to take marine mammals, by incidental Level B 
harassment only, while conducting Rim of the Pacific (RIMPAC) anti-
submarine (ASW) training events, in which submarines, surface ships, 
and aircraft from the United States and multiple foreign nations 
participate in ASW training exercises, utilizing mid-frequency sonar (1 
kilohertz (kHz) to 10 kHz), in the U.S. Navy's Hawaiian Operating Area 
(OpArea) during July, 2006.

DATES: Effective June 27, 2006, through August 15, 2006.

ADDRESSES: A copy of the IHA and the application are available by 
writing to Michael Payne, Chief, Permits, Conservation, and Education 
Division, Office of Protected Resources, National Marine Fisheries 
Service, 1315 East-West Highway, Silver Spring, MD 20910-3225, or by 
telephoning the contact listed here. A copy of the application 
containing a list of references used in this document may be obtained 
by writing to this address, by telephoning the contact listed here (see 
FOR FURTHER INFORMATION CONTACT) or online at: http://www.nmfs.noaa.gov/pr/permits/incidental.htm. Documents cited in this 
notice may be viewed, by appointment, during regular business hours, at 
the aforementioned address.

FOR FURTHER INFORMATION CONTACT: Donna Wieting, Office of Protected 
Resources, NMFS, (301) 713-2289.

SUPPLEMENTARY INFORMATION: 

Background

    Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 et seq.) 
direct the Secretary of Commerce to allow, upon request, the 
incidental, but not intentional, taking of marine mammals by U.S. 
citizens who engage in a specified activity (other than commercial 
fishing) within a specified geographical region if certain findings are 
made and either regulations are issued or, if the taking is limited to 
harassment, a notice of a proposed authorization is provided to the 
public for review.
    Authorization shall be granted if NMFS finds that the taking will 
have a negligible impact on the species or stock(s), will not have an 
unmitigable adverse impact on the availability of the species or 
stock(s) for subsistence uses, and that the permissible methods of 
taking and requirements pertaining to the mitigation, monitoring and 
reporting of such takings are set forth. NMFS has defined ``negligible 
impact'' in 50 CFR 216.103 as ''...an impact resulting from the 
specified activity that cannot be reasonably expected to, and is not 
reasonably likely to, adversely affect the species or stock through 
effects on annual rates of recruitment or survival.''
    Section 101(a)(5)(D) of the MMPA established an expedited process 
by which citizens of the United States can apply for an authorization 
to incidentally take small numbers of marine mammals by harassment. The 
National Defense Authorization Act of 2004 (NDAA) (Public Law 108-136) 
removed the ``small numbers'' limitation and amended the definition of 
``harassment'' as it applies to a ``military readiness activity'' to 
read as follows:

    (i) any act that injures or has the significant potential to 
injure a marine mammal or marine mammal stock in the wild [Level A 
Harassment]; or
    (ii) any act that disturbs or is likely to disturb a marine 
mammal or marine mammal stock in the wild by causing disruption of 
natural behavioral patterns, including, but not limited to, 
migration, surfacing, nursing, breeding, feeding, or sheltering, to 
a point where such behavioral patterns are abandoned or 
significantly altered [Level B Harassment]

    Section 101(a)(5)(D) establishes a 45-day time limit for NMFS 
review of an application followed by a 30-day public notice and comment 
period on any proposed authorizations for the incidental harassment of 
marine mammals. Within 45 days of the close of the comment period, NMFS 
must either issue or deny issuance of the authorization.

Summary of Request

    On March 16, 2006, NMFS received an application from the Navy for 
the taking, by harassment, of several species of marine mammals 
incidental to conducting RIMPAC ASW training events, in which 
submarines, surface ships, and aircraft from the United States and 
multiple foreign nations participate in ASW training exercises, in the 
OpArea, in the summer of 2006. The RIMPAC ASW exercises are considered 
a military readiness activity.
    NMFS may not authorize the take of marine mammals by non-U.S. 
citizens; however, all foreign vessels participating in RIMPAC 2006 
will be under the Operational Control (OPCON) of Commander, U.S. THIRD 
Fleet in his capacity as Officer Conducting the Exercise (OCE) and 
Commander, Combined Task Force (CCTF) RIMPAC (i.e., the Navy can 
require that a foreign vessel cease sonar operations). Additionally, 
all forces assigned, including foreign vessels, are required to comply 
with the environmental mitigation measures spelled out in the Navy's 
Annex L [Environmental], which will include all of the measures in the 
IHA, as a condition of participating in the exercise. This is part of 
the description of the activity.

Description of the Activity

    RIMPAC 2006 ASW activities are scheduled to take place from June 
26, 2006, to about July 28, 2006, with ASW training events planned on 
21 days. The OpArea is approximately 210,000 square nautical miles 
(nm), however, the majority of RIMPAC ASW training would occur in the 
six areas delineated in Figure 2-1 in the Navy's application 
(approximate 46,000 square nm). ASW events typically rotate between 
these six modeled areas. These six areas were used for analysis as 
being representative of the marine mammal habitats and the bathymetric, 
seabed, wind speed, and sound velocity profile conditions within the 
entire OpArea. For purposes of this analysis, all likely RIMPAC ASW 
events were modeled as occurring in these six areas.
    As a combined force during the exercises, submarines, surface 
ships, and aircraft will conduct ASW against opposition submarine 
targets. Submarine targets include real submarines, target drones that 
simulate the operations of an actual submarine, and virtual submarines 
interjected into the training events by exercise controllers. ASW 
training events are complex and highly variable. For RIMPAC, the 
primary event involves a Surface Action Group (SAG), consisting of one 
to five surface ships equipped with sonar, with one or more 
helicopters, and a P-3 aircraft searching for one or more submarines. 
There will be approximately four SAGs for RIMPAC 2006. For the purposes 
of analysis, each event in which a SAG

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participates is counted as an ASW operation. There will be 
approximately 44 ASW operations during RIMPAC with an average event 
length of approximately 12 hours.
    One or more ASW events may occur simultaneously within the OpArea. 
Each event was identified and modeled separately. If a break of more 
than 1 hour in ASW operations occurred, then the subsequent event was 
modeled as a separate event. Training event durations ranged from 2 
hours to 24 hours. A total of 532 training hours were modeled for 
RIMPAC acoustic exposures. This total includes all potential ASW 
training that is expected to occur during RIMPAC.

Active Acoustic Sources

    Tactical military sonars are designed to search for, detect, 
localize, classify, and track submarines. There are two types of 
sonars, passive and active. Passive sonars only listen to incoming 
sounds and, since they do not emit sound energy in the water, lack the 
potential to acoustically affect the environment. Active sonars 
generate and emit acoustic energy specifically for the purpose of 
obtaining information concerning a distant object from the sound energy 
reflected back from that object.
    Modern sonar technology has developed a multitude of sonar sensor 
and processing systems. In concept, the simplest active sonars emit 
omnidirectional pulses (``pings'') and time the arrival of the 
reflected echoes from the target object to determine range. More 
sophisticated active sonar emits an omnidirectional ping and then 
rapidly scans a steered receiving beam to provide directional, as well 
as range, information. More advanced sonars transmit multiple preformed 
beams, listening to echoes from several directions simultaneously and 
providing efficient detection of both direction and range.
    The tactical military sonars to be deployed in RIMPAC are designed 
to detect submarines in tactical operational scenarios. This task 
requires the use of the sonar mid-frequency (MF) range (1 kilohertz 
[kHz] to 10 kHz) predominantly.
    The types of tactical acoustic sources that would be used in 
training events during RIMPAC are discussed in the following 
paragraphs. For more information regarding how the Navy's determined 
which sources should not be included in their analysis, see the 
Estimates of Take Section later in this document.
    Surface Ship Sonars-A variety of surface ships participate in 
RIMPAC, including guided missile cruisers, destroyers, guided missile 
destroyers, and frigates. Some ships (e.g., aircraft carriers) do not 
have any onboard active sonar systems, other than fathometers. Others, 
like guided missile cruisers, are equipped with active as well as 
passive sonars for submarine detection and tracking. For purposes of 
the analysis, all surface ship sonars were modeled as equivalent to 
SQS-53 having the nominal source level of 235 decibels (dB) re 1mPa\2\-
s (SEL). Since the SQS-53 hull mounted sonar is the U.S. Navy's most 
powerful surface ship hull mounted sonar, modeling this source is a 
conservative assumption tending towards an overestimation of potential 
effects (although, the conservativeness is offset some by the fact that 
the Navy did not model for any of the times (though brief and 
infrequent) that they may use a source level higher than 235 dB). Sonar 
ping transmission durations were modeled as lasting 1 second per ping 
and directional with a footprint that was 240 degrees wide, which is a 
conservative assumption that overestimates potential exposures, since 
actual ping durations will be less than 1 second. The SQS-53 hull 
mounted sonar transmits at center frequencies of 2.6 kHz and 3.3 kHz.
    Submarine Sonars-Submarine sonars can be used to detect and target 
enemy submarines and surface ships. However, submarine active sonar use 
is very rare in the planned RIMPAC exercises, and, when used, very 
brief. Therefore, use of active sonar by submarines is unlikely to have 
any effect on marine mammals, and it was not modeled for RIMPAC 2006.
    Aircraft Sonar Systems-Aircraft sonar systems that would operate 
during RIMPAC include sonobuoys and dipping sonar. Sonobuoys may be 
deployed by P-3 aircraft or helicopters; dipping sonars are used by 
carrier-based helicopters. A sonobuoy is an expendable device used by 
aircraft for the detection of underwater acoustic energy and for 
conducting vertical water column temperature measurements. Most 
sonobuoys are passive, but some can generate active acoustic signals as 
well. Dipping sonar is an active or passive sonar device lowered on 
cable by helicopters to detect or maintain contact with underwater 
targets. During RIMPAC, these systems active modes are only used 
briefly for localization of contacts and are not used in primary search 
capacity. Because active mode dipping sonar use is very brief, it is 
extremely unlikely its use would have any effect on marine mammals. The 
AN/AQS 13 (dipping sonar) used by carrier based helicopters was 
determined in the Environmental Assessment/Overseas Environmental 
Assessment of the SH-60R Helicopter/ALFS Test Program, October 1999, 
not to be problematic due to its limited use and very short pulse 
length. Therefore, the aircraft sonar systems were not modeled for 
RIMPAC 2006.
    Torpedoes-Torpedoes are the primary ASW weapon used by surface 
ships, aircraft, and submarines. The guidance systems of these weapons 
can be autonomous or electronically controlled from the launching 
platform through an attached wire. The autonomous guidance systems are 
acoustically based. They operate either passively, exploiting the 
emitted sound energy by the target, or actively, ensonifying the target 
and using the received echoes for guidance. All torpedoes used for ASW 
during RIMPAC would be located in the range area managed by Pacific 
Missile Range Facility (PMRF) and would be non-explosive and recovered 
after use.
    Acoustic Device Countermeasures (ADC)-ADCs are, in effect, 
submarine simulators that make noise to act as decoys to avert 
localization and/or torpedo attacks. Previous classified analysis has 
shown that, based on the operational characteristics (source output 
level and/or frequency) of these acoustic sources, the potential to 
affect marine mammals was unlikely, and therefore they were not modeled 
for RIMPAC 2006.
    Training Targets-ASW training targets are used to simulate target 
submarines. They are equipped with one or a combination of the 
following devices: (1) acoustic projectors emanating sounds to simulate 
submarine acoustic signatures; (2) echo repeaters to simulate the 
characteristics of the echo of a particular sonar signal reflected from 
a specific type of submarine; and (3) magnetic sources to trigger 
magnetic detectors. Based on the operational characteristics (source 
output level and/or frequency) of these acoustic sources, the potential 
to affect marine mammals is unlikely, and therefore they were not 
modeled for RIMPAC 2006.
    Range Sources-Range pingers are active acoustic devices that allow 
each of the in-water platforms on the range (e.g., ships, submarines, 
target simulators, and exercise torpedoes) to be tracked by the range 
transducer nodes. In addition to passively tracking the pinger signal 
from each range participant, the range transducer nodes also are 
capable of transmitting acoustic signals for a limited set of 
functions. These functions include submarine warning signals, acoustic 
commands to submarine target simulators (acoustic command link), and 
occasional voice or

[[Page 38712]]

data communications (received by participating ships and submarines on 
range). Based on the operational characteristics (source output level 
and/or frequency) of these acoustic sources, the potential to affect 
marine mammals is unlikely, and therefore they were not modeled for 
RIMPAC 2006.
    For detailed information regarding the proposed activity, please 
see the Navy's application and the associated Environmental Assessment 
(EA) (see ADDRESSES).

Description of Marine Mammals Potentially Affected by the Activity

    There are 27 marine mammal species with possible or confirmed 
occurrence in the Navy's OpArea (Table 1): 25 cetacean species (whales, 
dolphins, and porpoises) and 2 pinnipeds (seals). In addition, five 
species of sea turtles are known to occur in the OpArea.
    The most abundant marine mammals are rough-toothed dolphins, dwarf 
sperm whales, and Fraser's dolphins. The most abundant large whales are 
sperm whales. There are three seasonally migrating baleen whale species 
that winter in Hawaiian waters: minke, fin, and humpback whales. 
Humpback whales utilize Hawaiian waters as a major breeding ground 
during winter and spring (November through April), but should not be 
present during the RIMPAC exercise, which takes place in July. Because 
definitive information on the other two migrating species is lacking, 
their possible presence during the July timeframe is assumed, although 
it is considered unlikely. Seven marine mammal species listed as 
federally endangered under the Endangered Species Act (ESA) occur in 
the area: the humpback whale, North Pacific right whale, sei whale, fin 
whale, blue whale, sperm whale, and Hawaiian monk seal.
    The Navy has used data compiled from available sighting records, 
literature, satellite tracking, and stranding and bycatch data to 
identify the species of marine mammals present in the OpArea. A 
combination of inshore survey data (within 25 nm (46 km); Mobley et 
al., 2000) and offshore data (from 25 nm (46 km) offshore out to the 
U.S. Exclusive Economic Zone (EEZ) (200 nm (370 km) (, Barlow 2003) was 
used to estimate the density and abundance of marine mammals within the 
OpArea (Table 1). Additional information regarding the status and 
distribution of the 27 marine mammal species that occur in the OpArea 
may be found in the Navy's application and the associated EA (see 
ADDRESSES) and in NMFS' Stock Assessment Reports, which are available 
at: http://www.nmfs.noaa.gov/pr/PR2/Stock_ Assessment --Program/ 
individual-- sars.html.
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Potential Effects on Marine Mammals

    NMFS has issued an IHA to the Navy for the take, by harassment, of 
marine mammals incidental to RIMPAC ASW exercises in the OpArea. 
Section 101(a)(5)(D) of the MMPA, the section pursuant to which IHAs 
are issued, may not be used to authorize mortality or serious injury 
leading to mortality. The Navy's analysis of the RIMPAC ASW exercises 
concluded that no mortality or serious injury leading to mortality 
would result from the proposed activities. However, NMFS believes, 
based on our interpretation of the limited available data bearing on 
this point, that some marine mammals may react to mid-frequency sonar, 
at received levels lower than those thought to cause direct physical 
harm, with behaviors that may, in some circumstances, lead to 
physiological harm, stranding, or, potentially, death. Therefore, NMFS 
has required additional mitigation and monitoring measures that were 
not originally proposed in the Navy's application, which are intended 
to ensure (in addition to the standard statutory requirement to effect 
the ``least practicable adverse impact upon the affected species or 
stock'') that mortality or serious injury leading to mortality does not 
result from the proposed activities.
    Below, NMFS describes the potential effects on marine mammals of 
exposure to tactical sonar.

Metrics Used in Acoustic Effect Discussions

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

SPL

    Sound pressure is the sound force per unit area, and is usually 
measured in micropascals (mPa), where 1 Pa is the pressure resulting 
from a force of one newton exerted over an area of one square meter.
    The sound levels to which most mammals are sensitive extend over 
many orders of magnitude and, for this reason, it is convenient to use 
a logarithmic scale (the decibel (dB) scale) when measuring sound. SPL 
is expressed as the ratio of a measured sound pressure and a reference 
level. The commonly used reference pressure level in underwater 
acoustics is 1 mPa, and the units for SPLs are dB re: 1 mPa.
    SPL (in dB) = 20 log (pressure / reference pressure)
    SPL is an instantaneous measurement and can be expressed as the 
peak, the peak-peak, or the root mean square (rms). Root mean square, 
which is the square root of the arithmetic average of the squared 
instantaneous pressure values, is typically used in discussions of the 
effects of sounds on vertebrates. SPL does not take the duration of a 
sound into account.

SEL

    In this proposed authorization, effect thresholds are expressed in 
terms of sound exposure level SEL. SEL is an energy metric that 
integrates the squared instantaneous sound pressure over a stated time 
interval. The units for SEL are dB re: 1 mPa\2\-s.
    SEL = SPL + 10log(duration)
    As applied to tactical sonar, the SEL includes both the ping SPL 
and the duration. Longer-duration pings and/or higher-SPL pings will 
have a higher SEL.
    If an animal is exposed to multiple pings, the SEL in each 
individual ping is summed to calculate the total SEL. Since mammalian 
threshold shift (TS) data show less effect from intermittent exposures 
compared to continuous exposures with the same energy (Ward, 1997), 
basing the effect thresholds on the total received SEL may be a 
conservative approach for treating multiple pings; as some recovery may 
occur between pings and lessen the effect of a particular exposure.
    The total SEL depends on the SPL, duration, and number of pings 
received. The acoustic effects on hearing that result in temporary 
threshold shift (TTS) and permanent threshold shift (PTS), do not imply 
any specific SPL, duration, or number of pings. The SPL and duration of 
each received ping are used to calculate the total SEL and determine 
whether the received SEL meets or exceeds the effect thresholds. For 
example, the sub-TTS behavioral effects threshold of 173 dB SEL would 
be reached through any of the following exposures:

    A single ping with SPL = 173 dB re 1 mPa and duration = 1 
second.A single ping with SPL = 170 dB re 1 mPa and duration = 2 
seconds.Two pings with SPL = 170 dB re 1 mPa and duration = 1 
second.Two pings with SPL = 167 dB re 1 mPa and duration = 2 
seconds.

Potential Physiological Effects

    Physiological function is any of a collection of processes ranging 
from biochemical reactions to mechanical interaction and operation of 
organs and tissues within an animal. A physiological effect may range 
from the most significant of impacts (i.e., mortality and serious 
injury) to lesser effects that would define the lower end of the 
physiological impact range, such as non-injurious short-term impacts to 
auditory tissues.
    Exposure to some types of noise may cause a variety of 
physiological effects in mammals. For example, exposure to very high 
sound levels may affect the function of the visual system, vestibular 
system, and internal organs (Ward, 1997). Exposure to high-intensity 
sounds of sufficient duration may cause injury to the lungs and 
intestines (e.g., Dalecki et al., 2002). Sudden, intense sounds may 
elicit a ``startle'' response and may be followed by an orienting 
reflex (Ward, 1997; Jansen, 1998). The primary physiological effects of 
sound, however, are on the auditory system (Ward, 1997).

Hearing Threshold Shift

    In mammals, high-intensity sound may rupture the eardrum, damage 
the small bones in the middle ear, or over-stimulate the 
electromechanical hair cells that convert the fluid motions caused by 
sound into neural impulses that are sent to the brain. Lower level 
exposures may cause hearing loss, which is called a threshold shift 
(TS) (Miller, 1974). Incidence of TS may be either permanent, in which 
case it is called a permanent threshold shift (PTS), or temporary, in 
which case it is called a temporary threshold shift (TTS). PTS consists 
of non-recoverable physical damage to the sound receptors in the ear, 
which can include total or partial deafness, or an impaired ability to 
hear sounds in specific frequency ranges. TTS is recoverable and is 
considered to result from temporary, non-injurious impacts to hearing-
related tissues. Hearing loss may affect an animal's ability to react 
normally to the sounds around it.
    The amplitude, duration, frequency, and temporal pattern of sound 
exposure all affect the amount of associated TS. As amplitude and 
duration of sound exposure increase, so, generally, does the amount of 
TS. For continuous sounds, exposures of equal energy will lead to 
approximately equal effects (Ward, 1997). For intermittent sounds, less 
TS will occur than from a continuous exposure with the same energy 
(some recovery will occur between exposures) (Kryter et al., 1966; 
Ward, 1997). Additionally, though TTS is temporary, very prolonged 
exposure to sound strong enough to elicit TTS, or shorter-term exposure 
to sound levels well above the TTS threshold, can cause

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PTS, at least in terrestrial mammals (Kryter, 1985).
    Additional detailed information regarding threshold shifts may be 
viewed in the Navy's RIMPAC application and in the USWTR DEIS.

Acoustically Mediated Bubble Growth

    One theoretical cause of injury to marine mammals is rectified 
diffusion (Crum and Mao, 1996), the process of increasing the size of a 
bubble by exposing it to a sound field. This process could be 
facilitated if the environment in which the ensonified bubbles exist is 
supersaturated with gas. Repetitive diving by marine mammals can cause 
the blood and some tissues to accumulate gas to a greater degree than 
is supported by the surrounding environmental pressure (Ridgway and 
Howard, 1979). The deeper and longer dives of some marine mammals (for 
example, beaked whales) are theoretically predicted to induce greater 
supersaturation (Houser et al., 2001b). If rectified diffusion were 
possible in marine mammals exposed to high-level sound, conditions of 
tissue supersaturation could theoretically speed the rate and increase 
the size of bubble growth. Subsequent effects due to tissue trauma and 
emboli would presumably mirror those observed in humans suffering from 
decompression sickness.
    It is unlikely that the short duration of sonar pings would be long 
enough to drive bubble growth to any substantial size, if such a 
phenomenon occurs. However, an alternative but related hypothesis has 
also been suggested: stable bubbles could be destabilized by high-level 
sound exposures such that bubble growth then occurs through static 
diffusion of gas out of the tissues. In such a scenario the marine 
mammal would need to be in a gas-supersaturated state for a long enough 
period of time for bubbles to become of a problematic size. Yet another 
hypothesis has speculated that rapid ascent to the surface following 
exposure to a startling sound might produce tissue gas saturation 
sufficient for the evolution of nitrogen bubbles (Jepson et al., 2003). 
In this scenario, the rate of ascent would need to be sufficiently 
rapid to compromise behavioral or physiological protections against 
nitrogen bubble formation. Collectively, these hypotheses can be 
referred to as ``hypotheses of acoustically mediated bubble growth.''
    Although theoretical predictions suggest the possibility for 
acoustically mediated bubble growth, there is considerable disagreement 
among scientists as to its likelihood (Piantadosi and Thalmann, 2004; 
Evans and Miller, 2003). To date, Energy Levels (ELs) predicted to 
cause in vivo bubble formation within diving cetaceans have not been 
evaluated (NOAA, 2002b). Further, although it has been argued that 
traumas from some recent beaked whale strandings are consistent with 
gas emboli and bubble-induced tissue separations (Jepson et al., 2003), 
there is no conclusive evidence of this. Because evidence supporting 
the potential for acoustically mediated bubble growth is debatable, 
this proposed IHA does not give it any special treatment. Additionally, 
the required mitigation measures, which are designed to avoid 
behavioral disruptions that could result in abnormal vertical movement 
by whales through the water column, should also reduce the potential 
for creating circumstances that theoretically contribute to harmful 
bubble growth.
    Additional information on the physiological effects of sound on 
marine mammals may be found in the Navy's IHA application and 
associated Environmental Assessment, the USWTR DEIS, and on the Ocean 
Acoustic Program section of the NMFS website (see ADDRESSES).

Stress Responses

    In addition to PTS and TTS, exposure to mid-frequency sonar is 
likely to result in other physiological changes that have other 
consequences for the health and ecological fitness of marine mammals. 
There is mounting evidence that wild animals respond to human 
disturbance in the same way that they respond to predators (Beale and 
Monaghan, 2004; Frid, 2003; Frid and Dill, 2002; Gill et al., 2000; 
Gill and Sutherland, 2001; Harrington and Veitch, 1992; Lima, 1998; 
Romero, 2004). These responses manifest themselves as interruptions of 
essential behavioral or physiological events, alteration of an animal's 
time or energy budget, or stress responses in which an animal perceives 
human activity as a potential threat and undergoes physiological 
changes to prepare for a flight or fight response or more serious 
physiological changes with chronic exposure to stressors (Frid and 
Dill, 2002; Romero, 2004; Sapolsky et al., 2000; Walker et al., 2005).
    Classic stress responses begin when an animal's central nervous 
system perceives a potential threat to its homeostasis. That perception 
triggers stress responses regardless of whether a stimulus actually 
threatens the animal; the mere perception of a threat is sufficient to 
trigger a stress response (Sapolsky et al., 2005; Seyle, 1950). Once an 
animal's central nervous system perceives a threat, it develops a 
biological response or defense that consists of a combination of the 
four general biological defense responses: behavioral responses, 
autonomic nervous system responses, neuroendocrine responses, or immune 
response.
    The physiological mechanisms behind stress responses involving the 
hypothalamus-pituitary-adrenal glands have been well-established 
through controlled experiment in the laboratory and natural settings 
(Korte et al. 2005; McEwen and Seeman, 2000; Moberg, 1985; 2000; 
Sapolsky et al., 2005). Relationships between these physiological 
processes, animal behavior, neuroendocrine responses, immune responses, 
inhibition of reproduction (by suppression of pre-ovulatory luteinizing 
hormones), and the costs of stress responses have also been documented 
through controlled experiment in both laboratory and free-living 
animals (for examples see, Holberton et al., 1996; Hood et al., 1998; 
Jessop et al., 2003; Krausman et al., 2004; Lankford et al., 2005; 
Reneerkens et al., 2002; Thompson and Hamer, 2000; Tilbrook et al., 
2000).
    The available evidence suggests that: with the exception of 
unrelieved pain or extreme environmental conditions, in most animals 
(including humans) chronic stress results from exposure to a series of 
acute stressors whose cumulative biotic costs produce a pathological or 
pre-pathological state in an animal. The biotic costs can result from 
exposure to an acute stressor or from the accumulation of a series of 
different stressors acting in concert before the animal has a chance to 
recover.
    Although these responses have not been explicitly identified in 
marine mammals, they have been identified in other vertebrate animals 
and every vertebrate mammal that has been studied, including humans. 
Because of the physiological similarities between marine mammals and 
other mammal species, NMFS believes that acoustic energy sufficient to 
trigger onset PTS or TTS is likely to initiate physiological stress 
responses. More importantly, NMFS believes that marine mammals might 
experience stress responses at received levels lower than those 
necessary to trigger onset TTS.

Potential Behavioral Effects

    For a military readiness activity, Level B Harassment is defined as 
``any act that disturbs or is likely to disturb a marine mammal or 
marine mammal stock in the wild by causing disruption of natural 
behavioral patterns, including, but not limited to, migration, 
surfacing, nursing,

[[Page 38716]]

breeding, feeding, or sheltering, to a point where such behavioral 
patterns are abandoned or significantly altered.''
    As discussed above, TTS consists of temporary, short-term impacts 
to auditory tissue that alter physiological function, but that are 
fully recoverable without the requirement for tissue replacement or 
regeneration. An animal that experiences a temporary reduction in 
hearing sensitivity suffers no permanent injury to its auditory system, 
but, for an initial time post-exposure, may not perceive some sounds 
due to the reduction in sensitivity. As a result, the animal may not 
respond to sounds that would normally produce a behavioral reaction 
(such as a predator or the social calls of conspecifics, which play 
important roles in mother-calf relations, reproduction, foraging, and 
warning of danger). This lack of response qualifies as a temporary 
disruption of normal behavioral patterns - the animal is impeded from 
responding in a normal manner to an acoustic stimulus.
    NMFS also considers disruption of the behavior of marine mammals 
that can result from sound levels lower than those considered necessary 
for TTS to occur (often referred to as sub-TTS behavioral disruption). 
Though few studies have specifically documented the effects of tactical 
mid-frequency sonar on the behavior of marine mammals in the wild, many 
studies have reported the effects of a wide range of intense 
anthropogenic acoustic stimuli on specific facets of marine mammal 
behavior, including migration (Malme et al., 1984; Ljungblad et al., 
1988; Richardson et al., 1999), feeding (Malme et al., 1988), and 
surfacing (Nowachek et al., 2004). Below, NMFS summarizes the results 
of two studies and one after-the-fact investigation wherein the natural 
behavior patterns of marine mammals exposed to levels of tactical mid-
frequency sonar, or sounds similar to mid-frequency sonar, lower than 
those thought to induce TTS were disrupted to the point where it was 
abandoned or significantly altered:
    (1) Finneran and Schlundt (2004) analyzed behavioral observations 
from related TTS studies (Schlundt et al., 2000; Finneran et al., 2001; 
2003) to calculate cetacean behavioral reactions as a function of known 
noise exposure. During the TTS experiments, four dolphins and two white 
whales were exposed during a total of 224 sessions to 1-s pulses 
between 160 and 204 dB re 1 mPa (root-mean-square sound pressure level 
(SPL)), at 0.4, 3, 10, 20, and 75 kHz. Finneran and Schlundt (2004) 
evaluated the behavioral observations in each session and determined 
whether a ``behavioral alteration'' (ranging from modifications of 
response behavior during hearing sessions to attacking the experimental 
equipment) occurred. For each frequency, the percentage of sessions in 
which behavioral alterations occurred was calculated as a function of 
received noise SPL. By pooling data across individuals and test 
frequencies, respective SPL levels coincident with responses by 25, 50, 
and 75 percent behavioral alteration were documented. 190 dB re 1 mPa 
(SPL) is the point at which 50 percent of the animals exposed to 3, 10, 
and 20 kHz tones were deemed to respond with some behavioral 
alteration, and the threshold that the Navy originally proposed for 
sub-TTS behavioral disturbance.
    (2) Nowacek et al. (2004) conducted controlled exposure experiments 
on North Atlantic right whales using ship noise, social sounds of con-
specifics, and an alerting stimulus (frequency modulated tonal signals 
between 500 Hz and 4.5 kHz). Animals were tagged with acoustic sensors 
(D-tags) that simultaneously measured movement in three dimensions. 
Whales reacted strongly to alert signals at received levels of 133-148 
dB SPL, mildly to conspecific signals, and not at all to ship sounds or 
actual vessels. The alert stimulus caused whales to immediately cease 
foraging behavior and swim rapidly to the surface. Although SEL values 
were not directly reported, based on received exposure durations, 
approximate received values were on the order of 160 dB re: 1 mPa\2\-s.
    (3) NMFS (2005) evaluated the acoustic exposures and coincident 
behavioral reactions of killer whales in the presence of tactical mid-
frequency sonar. In this case, none of the animals were directly fitted 
with acoustic dosimeters. However, based on a Naval Research Laboratory 
(NRL) analysis that took advantage of the fact that calibrated 
measurements of the sonar signals were made in situ and using advanced 
modeling to bound likely received exposures, estimates of received 
sonar signals by the killer whales were possible. Received SPL values 
ranged from 121 to 175 dB re: 1 mPa. The most probable SEL values were 
169.1 to 187.4 dB re: 1 mPa\2\-s; worst-case estimates ranged from 
177.7 to 195.8 dB re: 1 mPa\2\-s. Researchers observing the animals 
during the course of sonar exposure reported unusual alterations in 
swimming, breathing, and diving behavior.
    For more detailed information regarding how marine mammals may 
respond to sound, see the Navy's IHA application, the Navy's associated 
EA, Richardson's Marine Mammals and Noise (1995), or the references 
cited on NMFS' Ocean Acoustic Program website (see ADDRESSES)

Harassment Thresholds

    For the purposes of this IHA, NMFS recognizes three levels of take; 
Level A Harassment (Injury), Level B Harasssment (Behavioral 
Disruption), and mortality (or serious injury that may lead to 
mortality) (Table 2). Mortality, or serious injury leading to 
mortality, may not be authorized with an IHA.
    NMFS has determined that for acoustic effects, acoustic thresholds 
are the most effective way to consistently both apply measures to avoid 
or minimize the impacts of an action and to quantitatively estimate the 
effects of an action. Thresholds are commonly used in two ways: (1) To 
establish a shut-down or power down zone, i.e., if an animal enters an 
area calculated to be ensonified above the level of an established 
threshold, a sound source is powered down or shut down; and (2) to 
calculate take, for example, if the Level A Harassment threshold is 215 
dB, a model may be used to calculate the area around the sound source 
that will be ensonified to that level or above, then, based on the 
estimated density of animals and the distance that the sound source 
moves, NMFS can estimate the number of marine mammals exposed to 215 
dB. The rationale behind the acoustic thresholds proposed for this 
authorization are discussed below.

    Table 2. The three levels of take addressed in the MMPA, how NMFS
measures them in regard to acoustic effects, and the proposed thresholds
                         for this authorization
------------------------------------------------------------------------
 Levels of Take Pursuant to the
              MMPA                Basis of Threshold  Proposed Threshold
------------------------------------------------------------------------
Level A Harassment (Injury)       Permanent                  215 dB (SEL)
                                   Threshold Shift
                                   (PTS).
Level B Harassment (Behavioral    Temporary                  195 dB (SEL)
 Effects)                          Threshold Shift           173 dB (SEL)
                                   (TTS).
                                  Sub-TTS Behavioral
                                   Effects.

[[Page 38717]]

 
Mortality, or Serious Injury      Not enough                 May not be
 That May Lead to Mortality        information for    authorized with an
 (Stranding)                       quantitative                     IHA
                                   threshold.
------------------------------------------------------------------------

TTS

    Because it is non-injurious, NMFS considers TTS as Level B 
harassment (behavioral disruption) that is mediated by physiological 
effects on the auditory system. The smallest measurable amount of TTS 
(onset-TTS) is taken as the best indicator for slight temporary sensory 
impairment. However, as mentioned earlier, NMFS believes that 
behavioral disruptions may result from received levels of tactical 
sonar lower than those thought to induce TTS and, therefore, NMFS does 
not consider on-set TTS to be the lowest level at which Level B 
Harassment may occur. NMFS considers the threshold for Level B 
Harasment as the received levels from which sub-TTS behavioral 
disruptions are likely to result (discussed in Sub-TTS sub-section). 
However, the threshold for Level A Harassment (PTS) is derived from the 
threshold for TTS and, therefore, it is necessary to describe how the 
TTS threshold was developed.
    The proposed TTS threshold is primarily based on the cetacean TTS 
data from Schlundt et al. (2000). These tests used short-duration tones 
similar to sonar pings, and they are the most directly relevant data 
for the establishing TTS criteria. The mean exposure EL required to 
produce onset-TTS in these tests was 195 dB re 1 mPa\2\-s. This result 
is corroborated by the short-duration tone data of Finneran et al. 
(2000, 2003) and the long-duration noise data from Nachtigall et al. 
(2003a,b). Together, these data demonstrate that TTS in cetaceans is 
correlated with the received EL and that onset-TTS exposures are fit 
well by an equal-energy line passing through 195 dB re 1 mPa\2\-s.
    The justification for establishing the 195 dB acoustic criteria for 
TTS is described in detail in both the Navy's RIMPAC IHA application 
and the USWTR DEIS (see ADDRESSES).

PTS

    PTS consists of non-recoverable physical damage to the sound 
receptors in the ear and is, therefore, classified as Level A 
harassment under the MMPA. For acoustic effects, because the tissues of 
the ear appear to be the most susceptible to the physiological effects 
of sound, and because threshold shifts (TSs) tend to occur at lower 
exposures than other more serious auditory effects, NMFS has determined 
that permanent threshold shift (PTS) is the best indicator for the 
smallest degree of injury that can be measured. Therefore, the acoustic 
exposure associated with onset-PTS is used to define the lower limit of 
the Level A harassment.
    PTS data do not currently exist for marine mammals and are unlikely 
to be obtained due to ethical concerns. However, PTS levels for these 
animals may be estimated using TTS data and relationships between TTS 
and PTS. NMFS proposes the use of 215 dB re 1 mPa\2\-s as the acoustic 
threshold for PTS. This threshold is based on a 20 dB increase in 
exposure EL over that required for onset-TTS (195 dB). Extrapolations 
from terrestrial mammal data indicate that PTS occurs at 40 dB or more 
of TS, and that TS growth occurs at a rate of approximately 1.6 dB TS 
per dB increase in EL. There is a 34-dB TS difference between onset-TTS 
(6 dB) and onset-PTS (40 dB). Therefore, an animal would require 
approximately 20dB of additional exposure (34 dB divided by 1.6 dB) 
above onset-TTS to reach PTS.
    The justification for establishing the 215-dB acoustic criteria for 
PTS is described in detail in both the Navy's RIMPAC IHA application 
and the Undersea Warfare Training Range USWTR DEIS.

Sub-TTS Behavioral Disruption

    NMFS believes that behavioral disruption of marine mammals may 
result from received levels of mid-frequency sonar lower than those 
believed necessary to induce TTS, and further, that the lower limit of 
Level B Harassment may be defined by the received sound levels 
associated with these sub-TTS behavioral disruptions. As of yet, no 
controlled exposure experiments have been conducted wherein wild 
cetaceans are deliberately exposed to tactical mid-frequency sonar and 
their reactions carefully observed. However, NMFS believes that in the 
absence of controlled exposure experiments, the following 
investigations and reports (described previously in the Behavioral 
Effects section) constitute the best available scientific information 
for establishing an appropriate acoustic threshold for sub-TTS 
behavioral disruption: (1) Finneran and Schlundt (2004), in which 
behavioral observations from TTS studies of captive bottlenose dophins 
and beluga whales are analyzed as a function of known noise exposure; 
(2) Nowachek et al. (2004), in which controlled exposure experiments 
were conducted on North Atlantic right whales using ship noise, social 
sounds of con-specifics, and an alerting stimulus; and (3) NMFS (2005), 
in which the behavioral reactions of killer whales in the presence of 
tactical mid-frequency sonar were observed, and analyzed after the 
fact. Based on these three studies, NMFS has set the sub-TTS behavioral 
disruption threshold at 173 dB re 1 mPa\2\-s (SEL).
    The Finneran and Schlundt (2004) analysis is an important piece in 
the development of an appropriate acoustic threshold for sub-TTS 
behavioral disruption because: (1) researchers had superior control 
over and ability to quantify noise exposure conditions; (2) behavioral 
patterns of exposed marine mammals were readily observable and 
definable; and, (3) fatiguing noise consisted of tonal noise exposures 
with frequencies contained in the tactical mid-frequency sonar 
bandwidth. In Finneran and Schlundt (2004) 190 dB re 1 mPa (SPL) is the 
point at which 50 percent of the animals exposed to 3, 10, and 20 kHz 
tones were deemed to respond with some behavioral alteration. This 50 
percent behavior alteration level (190 dB SPL) may be converted to an 
SEL criterion of 190 dB re 1 mPa\2\-s (the numerical values are 
identical because exposure durations were 1-s), which provides 
consistency with the Level A (PTS) effects threshold, which are also 
expressed in SEL. The Navy proposed 190 dB (SEL) as the acoustic 
threshold for sub-TTS behavioral disruption in the first IHA 
application they submitted to NMFS.
    NMFS acknowledges the advantages arising from the use of behavioral 
observations in controlled laboratory conditions; however, there is 
considerable uncertainty regarding the

[[Page 38718]]

validity of applying data collected from trained captives conditioned 
to not respond to noise exposure in establishing thresholds for 
behavioral reactions of naive wild individuals to a sound source that 
apparently evokes strong reactions in some marine mammals. Although 
wide-ranging in terms of sound sources, context, and type/extent of 
observations reported, the large and growing body of literature 
regarding behavioral reactions of wild, naive marine mammals to 
anthropogenic exposure generally suggests that wild animals are 
behaviorally affected at significantly lower levels than those 
determined for captive animals by Finneran and Schlundt (2004). For 
instance, some cetaceans exposed to human noise sound sources, such as 
seismic airgun sounds and low frequency sonar signals, have been shown 
to exhibit avoidance behavior when the animals are exposed to noise 
levels of 140-160 dB re: 1 mPa under certain conditions (Malme et al., 
1983; 1984; 1988; Ljungblad et al., 1988; Tyack and Clark, 1998). 
Richardson et al. (1995) reviewed the behavioral response data for many 
marine mammal species and a wide range of human sound sources.
    Two specific situations for which exposure conditions and 
behavioral reactions of free-ranging marine mammals exposed to sounds 
very similar to those proposed for use in RIMPAC are considered by 
Nowacek et al. (2004) and NMFS (2005) (described previously in 
Behavioral Effects subsection). In the Nowacek et al. (2004) study, 
North Atlantic right whales reacted strongly to alert signals at 
received levels of 133-148 dB SPL, which, based on received exposure 
durations, is approximately equivalent to 160 dB re: 1 mPa\2\-s (SEL). 
In the NMFS (2005) report, unusual alterations in swimming, breathing, 
and diving behaviors of killer whales observed by researchers in Haro 
Strait were correlated, after the fact, with the presence of estimated 
received sound levels between 169.1and 187.4 dB re: 1 mPa\2\-s (SEL).
    While acknowledging the limitations of all three of these studies 
and noting that they may not necessarily be predictive of how wild 
cetaceans might react to mid-frequency sonar signals in the OpArea, 
NMFS believes that these three studies are the best available science 
to support the selection of an acoustic sub-TTS behavioral disturbance 
threshold at this time. Taking into account all three studies, NMFS has 
established 173 dB re: 1 mPa\2\ (SEL) as the threshold for sub-TTS 
behavioral disturbance.

Stranding and Mortality

    Over the past 10 years, there have been four stranding events 
coincident with military mid-frequency sonar use that are believed to 
most likely have been caused by exposure to the sonar. These occurred 
in Greece (1996), the Bahamas (2000), Madeira (2000) and Canary Islands 
(2002). In 2004, during the RIMPAC exercises, between 150-200 usually 
pelagic melon-headed whales occupied the shallow waters of the Hanalei 
Bay, Kaua'i, Hawaii for over 28 hours. NMFS determined that the mid-
frequency sonar was, a plausible, if not likely, contributing factor in 
what may have been a confluence of events that led to the Hanalei Bay 
stranding. A number of other stranding events coincident with the 
operation of mid-frequency sonar and resulting in the death of beaked 
whales or other species (minke whales, dwarf sperm whales, pilot 
whales) have been reported, though the majority have not been 
investigated to the level of the Bahamas stranding and, therefore, 
other causes cannot be ruled out.

Greece, Madeira, and Canary Islands

    Twelve Cuvier's beaked whales stranded along the western coast of 
Greece in 1996. The test of a low- and mid-frequency active sonar 
system conducted by NATO was correlated with the strandings by an 
analysis published in Nature. A subsequent NATO investigation found the 
strandings to be closely related, in time, to the movements of the 
sonar vessel, and ruled out other physical factors as a cause.
    In 2000, four beaked whales stranded in Madeira while several NATO 
ships were conducting an exercise near shore. Scientists investigating 
the stranding found that the injuries, which included blood in and 
around the eyes, kidney lesions, and pleural hemorrhage, as well as the 
pattern of the stranding suggested that a similar pressure event 
precipitated or contributed to strandings in both Madeira and Bahamas 
(see Bahamas sub-section).
    In 2002, at least 14 beaked whales of three different species 
stranded in the Canary Islands while a naval exercise including Spanish 
vessels, U.S. vessels, and at least one vessel equipped with mid-
frequency sonar was conducted in the vicinity. Four more beaked whales 
stranded over the next several days. The subsequent investigation, 
which was reported in both Nature and Veterinary Pathology, revealed a 
variety of traumas, including emboli and lesions suggestive of 
decompression sickness.

Bahamas

    NMFS and the Navy prepared a joint report addressing the multi-
species stranding in the Bahamas in 2000, which took place within 24 
hours of U.S. Navy ships using active mid-frequency sonar as they 
passed through the Northeast and Northwest Providence Channels. Of the 
17 cetaceans that stranded (Cuvier's beaked whales, Blainsville's 
beaked whales, Minke whales, and a spotted dolphin), seven animals died 
on the beach (5 Cuvier's beaked whales, 1 Blainsville's beaked whale, 
and the spotted dolphin) and the other 10 were returned to the water 
alive (though their fate is unknown). A comprehensive investigation was 
conducted and all possible causes of the stranding event were 
considered, whether they seemed likely at the outset or not. The only 
possible contributory cause to the strandings and cause of the lesions 
that could not be ruled out was intense acoustic signals (the dolphin 
necropsy revealed a disease and the death is considered unrelated to 
the others).
    Based on the way in which the strandings coincided with ongoing 
naval activity involving tactical mid-frequency sonar use, in terms of 
both time and geography, the nature of the physiological effects 
experienced by the dead animals, and the absence of any other acoustic 
sources, the investigation team concluded that mid-frequency sonars 
aboard U.S. Navy ships that were in use during the sonar exercise in 
question were the most plausible source of this acoustic or impulse 
trauma. This sound source was active in a complex environment that 
included the presence of a surface duct, unusual and steep bathymentry, 
a constricted channel with limited egress, intensive use of multiple, 
active sonar units over an extended period of time, and the presence of 
beaked whales that appear to be sensitive to the frequencies produced 
by these sonars. The investigation team concluded that the cause of 
this stranding event was the confluence of the Navy mid-frequency sonar 
and these contributory factors working together, and further 
recommended that the Navy avoid operating mid-frequency sonar in 
situations where these five factors would be likely to occur. This 
report does not conclude that all five of these factors must be present 
for a stranding to occur, nor that beaked whales are the only species 
that could potentially be affected by the confluence of the other 
factors. Based on this, NMFS believes that the presence of surface 
ducts, steep bathymetry, and/or constricted channels added to the 
operation of mid-frequency

[[Page 38719]]

sonar in the presence of cetaceans (especially beaked whales and, 
potentially, deep divers) may increase the likelihood of producing a 
sound field with the potential to cause cetaceans to strand, and 
therefore, necessitates caution.

Hanalei Bay

    On July 3-4, 2004, between 150-200 melon-headed whales occupied the 
shallow waters of the Hanalei Bay, Kaua'i, Hawaii for over 28 hours. 
Attendees of a canoe blessing observed the animals entering the Bay in 
a single wave formation at 7 a.m. on July 3, 2004. The animals were 
observed moving back into the shore from the mouth of the Bay at 9 a.m. 
The usually pelagic animals milled in the shallow bay and were returned 
to deeper water with human assistance beginning at 9:30 a.m. on July 4, 
2004, and were out of sight by 10:30 a.m.
    Only one animal, a calf, was known to have died (on July 5, 2004) 
following this event. The animal was noted alive and alone in the Bay 
on the afternoon of July 4, 2004 and was found dead in the Bay the 
morning of July 5, 2004. On July 7, 2004, a full necropsy, magnetic 
resonance imaging, and computerized tomography examination were 
performed on the calf to determine the manner and cause of death. The 
combination of imaging, necropsy and histological analyses found no 
evidence of infectious, internal traumatic, congenital, or toxic 
factors. Although cause of death could not be definitively determined, 
it is likely that maternal separation, poor nutritional condition, and 
dehydration contributed to the final demise of the animal. Although we 
do not know when the calf was separated from its mother, the movement 
into the Bay, the milling and re-grouping may have contributed to the 
separation or lack of nursing especially if the maternal bond was weak 
or this was a primiparous calf.
    Environmental factors, abiotic and biotic, were analyzed for any 
anomalous occurrences that would have contributed to the animals 
entering and remaining in Hanalei Bay. The Bay's bathymetry is similar 
to many other sites within the Hawaiian Island chain and dissimilar to 
sites that have been associated with mass strandings in other parts of 
the United States. The weather conditions appeared to be normal for 
that time of year with no fronts or other significant features noted. 
There was no evidence of unusual distribution or occurrence of predator 
or prey species, or unusual harmful algal blooms. Weather patterns and 
bathymetry that have been associated with mass strandings elsewhere 
were not found to occur in this instance.
    This event was spatially and temporally correlated with RIMPAC. 
Official sonar training and tracking exercises in the Pacific Missile 
Range Facility (PMRF) warning area did not commence until approximately 
8 a.m. on July 3 and were thus ruled out as a possible trigger for the 
initial movement into the Bay.
    However, the six naval surface vessels transiting to the 
operational area on July 2 intermittently transmitted active sonar (for 
approximately 9 hours total from 1:15 p.m. to 12:30 a.m.) as they 
approached from the south. The potential for these transmissions to 
have triggered the whales' movement into Hanalei Bay was investigated. 
Analyses with the information available indicated that animals to the 
south and east of Kaua'i could have detected active sonar transmissions 
on July 2, and reached Hanalei Bay on or before 7 a.m. on July 3, 2004. 
However, data limitations regarding the position of the whales prior to 
their arrival in the Bay, the magnitude of sonar exposure, behavioral 
responses of melon-headed whales to acoustic stimuli, and other 
possible relevant factors preclude a conclusive finding regarding the 
role of sonar in triggering this event. Propagation modeling suggest 
that transmissions from sonar use during the July 3 exercise in the 
PMRF warning area may have been detectable at the mouth of the Bay. If 
the animals responded negatively to these signals, it may have 
contributed to their continued presence in the Bay. The U.S. Navy 
ceased all active sonar transmissions during exercises in this range on 
the afternoon of July 3, 2004. Subsequent to the cessation of sonar 
use, the animals were herded out of the Bay.
    While causation of this stranding event may never be unequivocally 
determined, we consider the active sonar transmissions of July 2-3, 
2004, a plausible, if not likely, contributing factor in what may have 
been a confluence of events. This conclusion is based on: (1) the 
evidently anomalous nature of the stranding; (2) its close 
spatiotemporal correlation with wide-scale, sustained use of sonar 
systems previously associated with stranding of deep-diving marine 
mammals; (3) the directed movement of two groups of transmitting 
vessels toward the southeast and southwest coast of Kaua'i; (4) the 
results of acoustic propagation modeling and an analysis of possible 
animal transit times to the Bay; and (5) the absence of any other 
compelling causative explanation. The initiation and persistence of 
this event may have resulted from an interaction of biological and 
physical factors. The biological factors may have included the presence 
of an apparently uncommon, deep-diving cetacean species (and possibly 
an offshore, non-resident group), social interactions among the animals 
before or after they entered the Bay, and/or unknown predator or prey 
conditions. The physical factors may have included the presence of 
nearby deep water, multiple vessels transiting in a directed manner 
while transmitting active sonar over a sustained period, the presence 
of surface sound ducting conditions, and/or intermittent and random 
human interactions while the animals were in the Bay.

Beaked Whales

    Recent beaked whale strandings have prompted inquiry into the 
relationship between mid-frequency active sonar and the cause of those 
strandings. A review of world-wide cetacean mass stranding data reveals 
that beaked whales have been the most common taxa involved in stranding 
events (approximately 67 percent of all strandings include beaked 
whales), with Cuvier's beaked whales accounting for about 90 percent of 
the individual beaked whales. Although the confluence of Navy mid-
frequency active tactical sonar with the other contributory factors 
noted in the report was identified as the cause of the 2000 Bahamas 
stranding event, the specific mechanisms that led to that stranding are 
not understood, and there is uncertainty regarding the ordering of 
effects that led to the stranding. It is uncertain whether beaked 
whales were directly injured by sound (a physiological effect) prior to 
stranding or whether a behavioral response to sound occurred that 
ultimately caused the beaked whales to strand and be injured.
    Several potential physiological outcomes caused by behavioral 
responses to high-intensity sounds have been suggested by Cox et al. 
(in press). These include: gas bubble formation caused by excessively 
fast surfacing; remaining at the surface too long when tissues are 
supersaturated with nitrogen; or diving prematurely when extended time 
at the surface is necessary to eliminate excess nitrogen. Baird et al. 
(2005) found that slow ascent rates from deep dives and long periods of 
time spent within 50 m of the surface were typical for both Cuvier's 
and Blainsville's beaked whales, the two species involved in mass 
strandings related to naval sonar. These two behavioral mechanisms may 
be necessary to purge excessive dissolved nitrogen concentrated in 
their tissues

[[Page 38720]]

during their frequent long dives (Baird et al., 2005). Baird et al. 
(2005) further suggests that abnormally rapid ascents or premature 
dives in response to high-intensity sonar could indirectly result in 
physical harm to the beaked whales, through the mechanisms described 
above (gas bubble formation or non-elimination of excess nitrogen).
    During the RIMPAC exercise there will be use of multiple sonar 
units in an area where three beaked whale species may be present. A 
surface duct may be present in a limited area for a limited period of 
time. Although most of the ASW training events will take place in the 
deep ocean, some will occur in areas of high bathymetric relief. 
However, none of the training events will take place in a location 
having a constricted channel with limited egress similar to the 
Bahamas. Consequently, not all five of the environmental factors 
believed to contribute to the Bahamas stranding (mid-frequency sonar, 
beaked whale presence, surface ducts, steep bathymetry, and constricted 
channels with limited egress) will be present during RIMPAC ASW 
exercises. However, as mentioned previously, NMFS believes caution 
should be used anytime either steep bathymetry, surface ducting 
conditions, or a constricted channel is present in addition to the 
operation of mid-frequency tactical sonar and the presence of cetaceans 
(especially beaked whales).

Estimated Take by Incidental Harassment

    In order to estimate acoustic exposures from the RIMPAC ASW 
operations, acoustic sources to be used were examined with regard to 
their operational characteristics. Systems with acoustic source levels 
below 205 dB re 1 mPa were not included in the analysis given that at 
this source level (205 dB re 1 mPa) or below, a 1-second ping would 
attenuate below the Level B Harassment behavioral disturbance threshold 
of 173 dB at a distance of about 100 meters, which is well within the 
required shutdown zone. Also, animals are expected to avoid the 
exercises by a distance greater than that and their detectibility is 
higher at that distance. In addition, systems with an operating 
frequency greater than 100 kHz were not analyzed in the detailed 
modeling, as these signals attenuate rapidly, resulting in very short 
propagation distances. Acoustic countermeasures were previously 
examined and found not to be problematic. The AN/AQS 13 (dipping sonar) 
used by carrier based helicopters was determined in the Environmental 
Assessment/Overseas Environmental Assessment of the SH-60R Helicopter/
ALFS Test Program, October 1999, not to be problematic due to its 
limited use and very short pulse length (2 to 5 pulses of 3.5 to 700 
msec). Since 1999, during the time of the test program, there have been 
over 500 hours of operation, with no environmental effects observed. 
The Directional Command Activated Sonobuoy System (DICASS) sonobuoy was 
determined not to be problematic, having a source level of 201 dB re 1 
mPa. These acoustic sources, therefore, did not require further 
examination in this analysis.
    Based on the information above, only hull mounted mid-frequency 
active tactical sonar was determined to have the potential to affect 
marine mammals during RIMPAC ASW training events.

Model

    An analysis was conducted for RIMPAC 2006, modeling the potential 
interaction of hull mounted mid-frequency active tactical sonar with 
marine mammals in the OpArea. The model incorporates site-specific 
bathymetric data, time-of-year-specific sound speed information, the 
sound source's frequency and vertical beam pattern, and multipath 
pressure information as a function of range, depth and bearing. Results 
were calculated based on the typical ASW activities planned for RIMPAC 
2006. Acoustic propagation and mammal population and density data were 
analyzed for the July timeframe since RIMPAC occurs in July. The 
modeling occurred in five broad steps, listed below.
    Step 1. Perform a propagation analysis for the area ensonified 
using spherical spreading loss and the Navy's CASS/GRAB program, 
respectively.
    Step 2. Convert the propagation data into a two-dimensional 
acoustic footprint for the acoustic sources engaged in each training 
event as they move through the six acoustic exposure model areas.
    Step 3. Calculate the total energy flux density level for each 
ensonified area summing the accumulated energy of all received pings.
    Step 4. Compare the total energy flux density to the thresholds and 
determine the area at or above the threshold to arrive at a predicted 
marine mammal exposure area.
    Step 5. Multiply the exposure areas by the corresponding mammal 
population density estimates. Sum the products to produce species sound 
exposure rate. Analyze this rate based on the annual number of events 
for each exercise scenario to produce annual acoustic exposure 
estimates.
    Based on the modeled estimate, NMFS anticipates take of 21 
cetaceans and no pinnipeds. The results of the model (estimated Level B 
Harassment takes) are presented in Table 1. The model actually 
estimated potential take of 1 Hawaiian monk seal, however, because of 
the anticipated effectiveness of the mitigation measures and distance 
of the majority of the exercises from land, NMFS does not anticipate 
any take of monk seals, and it is not authorized.
    When analyzing the results of the acoustic exposure modeling to 
provide an estimate of effects, it is important to understand that 
there are limitations to the ecological data used in the model, and 
that the model results must be interpreted within the context of a 
given species' ecology and biology.
    NMFS believes that the model take estimates may be overestimates 
for the following reasons:
    (1) The implementation of the extensive mitigation and monitoring 
that will be required by the IHA (Including large power-down/shut-down 
zones, geographic restrictions, and monitors that will almost certainly 
sight groups of animals, if not individuals, in time to avoid/minimize 
impacts) have not been taken into account.
    (2) In the model the Navy used to estimate take, marine mammals 
remain stationary as the sound source passes by and their immediate 
area is ensonified. NMFS believes that some, if not the majority of 
animals, will move away from the sound to some degree, thus receiving a 
lower level of energy than estimated by the model.
    (3) In the Navy's model, sound levels were calculated for every 5 m 
(16 ft) wide by 5 m (16 ft) long by 2 m (7 ft) deep section within the 
ensonified area. Then, for each 5 m (16 ft) by 5 m (16 ft) column of 
the ocean, the sound level through that entire water column was assumed 
to be whatever the sound level was in the loudest 2 m (7 ft) deep 
section of that water column.
    (4) NMFS interprets the results of the Navy's model as the number 
of times marine mammals might be exposed to particular received levels 
of sound. However, NMFS believes it would be unrealistic, considering 
the fast-paced, multi-vessel nature of the exercise and the fact that 
the exercise continues over the course of a month in an area with 
resident populations of cetaceans, to assume that each exposure 
involves a different whale; some whales are likely to be exposed once, 
while others are likely to be exposed more than once.Some elements of 
the Navy's modeling, such as its calculation of received levels without 
regard to where

[[Page 38721]]

animals occur in the water column, are conservative. Other elements, 
such as its evaluation of some but not all acoustic sources that would 
be used during the exercise, may not be conservative. It is NMFS view 
that an extensive set of mitigation and monitoring requirements like 
those set forth in this notice would ensure that impacts on species and 
stocks are negligible. This conclusion would not necessarily apply to 
other naval acoustic activities whose operational and environmental 
parameters may differ.

Potential Effects on Habitat

    The primary source of marine mammal habitat impact is acoustic 
exposures resulting from ASW activities. However, the exposures do not 
constitute a long term physical alteration of the water column or 
bottom topography, as the occurrences are of limited duration and are 
intermittent in time. Surface vessels associated with the activities 
are present in limited duration and are intermittent as well.

Potential Effects on Subsistence Harvest of Marine Mammals

    There is no known legal subsistence hunting for marine mammals in 
or near the survey area, so the proposed activities will not have any 
impact on the availability of the species or stocks for subsistence 
users.

Comments and Responses

    On April 24, 2006 (71 FR 20987), NMFS published a notice of a 
proposed IHA for the Navy's request to take marine mammals incidental 
to the RIMPAC ASW exercises and requested comments, information and 
suggestions concerning the request. During the 30-day public comment 
period, NMFS received approximately 125 comments from private citizens 
and several sets of comments from non-governmental organizations, 
including the Marine Mammal Commission (MMC), the Natural Resources 
Defense Council (which commented on behalf of the International Fund 
for Animal Welfare, Cetacean Society International, the League for 
Coastal Protection, Ocean Futures Society, Jean-Michel Cousteau, the 
Humane Society of the United States, the Center for Biological 
Diversity, and Oceana) (NRDC et al.), the Cascadia Research Collective 
(CRC), Seaflow, the Animal Welfare Institute (AWI), the Pacific Whale 
Foundation (PWF), the Whale and Dolphin Conservation Society (WDCS), 
and the Center for Regulatory Effectiveness (CRE). The comments have 
been sorted into general topic areas and are addressed below.

Mitigation Measures

    Comment 1: The coastal exclusion zone recommended in the proposed 
IHA (25 km (13.5 nm) is not large enough to adequately protect island 
associated populations of odontocetes from significant impacts, as 
aerial surveys indicate that short-finned pilot whales, spotted 
dolphins, spinner dolphins, and bottlenose dolphins occur in greater 
densities within 25 nm (46 km) of shore. Additionally, the comments 
point out, during the Hanalei stranding in 2004, signals from ships in 
the PMRF, some 40-50 km (21-26 nm) away, peaked above 150 dB re 1 miPa 
at the mouth of Hanalei Bay.
    Response: The main reasons behind requiring the Navy to maintain a 
25 km coastal exclusion zone around the 200 m (656 ft) isobath were to 
avoid the confluence of the factors that we know contributed to the 
stranding in the Bahamas (see Strandings section), to avoid driving 
deep-diving animals up onto the shelf-break where they might become 
disoriented, and to minimize impacts to island associated animals. In 
an effort to reduce the possibility of a repeat of the circumstances 
present during the Hanalei event (and to generally better avoid the 
confluence of the five Bahamas factors), NMFS did propose an additional 
mitigation measure that would require a 25-nm (46-km) (plus 2-nm (3.7-
buffer) coastal exclusion zone. Following is an explanation from the 
Navy explaining why the 25-nm (46-km) buffer is impracticable:

    Littoral waterspace is where the enemy will operate. The littoral 
waterspace is also the most challenging area to operate in due to a 
diverse acoustic environment found there. It is not realistic to 
refrain from training in the areas that are the most challenging and 
operationally unavoidable. The [25 nm (46 km) buffer] would remove 
realism from precursor operations and tactical development culminating 
in choke point transits. The proposal would remove ASW operations from 
the AMPHIB phase of the training, which is arguably the highest period 
of risk for our forces.
    NMFS must balance protective measures with practicability and we 
believe that the 25 km (13.5 nm) buffer effectively reduces the effects 
to island associated cetaceans while allowing the Navy to effectively 
carry out their mission.
    Comment 2: Two commenters recommended that NMFS implement a sonar 
exclusion zone around sea mounts, where species associated with steep, 
sloping areas may be exposed, and cyclonic eddies, which can result in 
significant increases in primary productivity and have been linked to 
significant increases in higher trophic species.
    Response: In regard to cyclonic eddies, NMFS believes that the 
impracticability to the Navy of avoiding these features outweighs the 
potential conservation gain. Though many species may congregate near 
cyclonic eddies, cyclonic eddies are very large, and, so restricting 
access to the full extent of these features to avoid animals that may 
congregate in a small subset of the total areas is not practicable. 
NMFS proposed a mitigation measure that would require the Navy to avoid 
seamounts, however, the Navy informed NMFS that this restriction would 
be impracticable because of the following operational impacts of having 
to steer clear of seamounts:

    Submarine tracking is a long and complicated tactical procedure. 
The training value of these procedures would be lost if operations were 
terminated when nearing seamounts prior to reaching the training 
objectives. Seamounts impact the way sound travels in water as well as 
our ability to search and track submarines. If we do not train near 
seamounts and understand how they affect our ability to search and 
track a submarine, we will be unable to do so when required against an 
actual threat. Submarine search planning is a detailed process that 
requires flexibility and large operating areas. If we avoided searching 
or tracking submarines near sea mounts, ASW operators will be severely 
limited in their ability to execute effective plans.
    Comment 3: One commenter points out that pursuant to Executive 
Order (E.O.) 13158, NMFS must consider and ``to the maximum extent 
practicable'' avoid harm to the protected natural and cultural 
resources of all Federal and State-designated protected areas (Marine 
Protected Areas (MPAs)) including, but not limited to, the Hawaiian 
Islands Humpback Whale National Marine Sanctuary.
    Response: Both the Hawaiian Islands Humpback Whale National Marine 
Sanctuary (HIHWNMS) and the newly designated Northwestern Hawaiian 
Islands Marine National Monument fall within in the Navy's Hawaiian 
Islands OpArea, and at times during RIMPAC exercises portions of their 
waters may be ensonified. Though the HIHWNMS is an important breeding 
area for Humpback whales during the winter and spring, the exercises 
will be

[[Page 38722]]

conducted in July when no humpback whales are expected to be present.
    The Northwestern Hawaiian Islands Marine National Monument 
proclamation contains the following language ``The prohibitions 
required by this proclamation shall not apply to activities and 
exercises of the Armed Forces (including those carried out by the 
United States Coast Guard) that are consistent with applicable laws.''
    As mentioned above, the effects of this action are temporary and 
acoustic in nature, and NMFS does not expect them to result in harm to 
the protected natural and cultural resources of these areas.
    Comment 4: One commenter suggested NMFS should not authorize sonar 
use during ship transits between exercises, as this is the same 
activity (same levels, same area), according to the NMFS Hanalei Bay 
Stranding Report, that was a ``plausible, if not likely'' contributor 
to the 2004 mass stranding event of melon-headed whales in Hanalei Bay.
    Response: According to the Navy, the sonar use that occurred prior 
to the Hanalei event was part of a designated exercise, not sonar use 
while in transit between exercises. Though the Navy could potentially 
operate sonar in the same place and manner it did during RIMPAC 2004, 
it does not necessarily mean that the other contributing factors to the 
stranding would be in place again. Also, unlike 2004, NMFS has included 
in the IHA a specific set of shutdown criteria that require the Navy 
cease operating sonar as soon as a ``milling out of habitat'' event 
involving a group of ten or more animals (such as in Hanalei) is 
verified.
    Comment 5: Several commenters noted that the Navy plans not to 
operate sonar over 235 dB except for occasional, short periods of time. 
These commenters further assert that the Navy did not model marine 
mammal take at levels above 235 dB and, therefore, NMFS has failed to 
assess all reasonably foreseeable impacts as required by National 
Environmental Policy Act (NEPA) and the MMPA. One commenter thought 
that the Navy should define what ``occasional short periods'' are and 
identify the higher source level while another commenter recommended 
limiting sonar output to 235 dB throughout the exercise.
    Response: NMFS proposed an additional mitigation measure that would 
have required the Navy not operate sonar over 235 dB, however, the Navy 
informed us that they could not implement the measure because it is 
impracticable for the following reasons:
    This measure limits tactical options and the specific reasons 
that it should not be agreed to are classified. Generally, however, 
realistic training requires flexibility to operate sonar as fits the 
tactical scenario and environment encountered. Sonar configuration 
and operation is dependent upon the environment. These conditions 
cannot be predicted a month in advance and a ship may find it 
necessary to transmit at power levels above 235 dB to address a 
situation as they would during a real world ASW event. To place an 
artificial requirement as requested decreases the training value and 
does not allow our sailors to train as we expect them to fight.
    In a ``classified'' document, the Navy provided information to the 
appropriate recipients at NMFS that discusses when and under what 
circumstances the source level above 235 dB is used. After reviewing 
the document, NMFS determined that the occasional operation of sonar 
above 235 dB does not affect our conclusions pursuant to NEPA, ESA, or 
MMPA.
    NMFS proposed an additional mitigation measure that would have 
required the Navy not operate sonar over 235 dB, however, the Navy 
informed us that they could not implement the measure because it is 
impracticable for the following reasons:
    This measure limits tactical options and the specific reasons 
that it should not be agreed to are classified. Generally, however, 
realistic training requires flexibility to operate sonar as fits the 
tactical scenario and environment encountered. Sonar configuration 
and operation is dependent upon the environment. These conditions 
cannot be predicted a month in advance and a ship may find it 
necessary to transmit at power levels above 235 dB to address a 
situation as they would during a real world ASW event. To place an 
artificial requirement as requested decreases the training value and 
does not allow our sailors to train as we expect them to fight.
    Comment 6: One commenter suggests that because of the considerable 
reduction in the range of effects gained by a reduction in source 
level, NMFS must consider requiring the Navy to operate at source 
levels below 235 dB throughout the exercise or at least in some 
circumstances.Response: NMFS is requiring the Navy to operate sonar at 
lower levels under some circumstances through monitoring of safety 
zones, and with larger safety zones in surface duct conditions and low 
visibility situations.
    Comment 7: NMFS received several comments regarding the proposed 
safety zones. One commenter suggested that the proposed outer safety 
zones (1000 m (3280 ft), or 2000 m (6561 ft) in special circumstances) 
are inadequate because they are inconsistent with NMFS 173 dB 
threshold. They further suggested that the distances are arbitrary and 
capricious.
    Response: NMFS marine mammal incidental take authorizations 
typically require a shutdown zone that corresponds to the isopleth 
associated with the Level A harassment threshold. NMFS does not require 
shutdown at the threshold associated with the onset of Level B 
Harassment (173 dB in this case), as that would effectively be an 
avoidance of take, which would render a take authorization unnecessary. 
In the case of RIMPAC, the 1000 m safety zone (at which powerdown 
begins) is estimated as corresponding to the more conservative (than 
typical PTS shutdown threshold) TTS threshold (195 SEL), and as such, 
is neither arbitrary nor inadequate.
    Comment 8: One commenter suggested that the proposed safety zones 
fail to meet the ``least practicable impact'' standard because the 
Australian Navy uses a 4000-m (2.2 nm) safety zone for sonar systems 
operating below 235 dB
    Response: NMFS has implemented a 1000-m (3280 ft) safety zone under 
normal conditions, a 2000 m (6561 ft) safety zone in low visibility 
conditions and surface-ducting conditions, and a 2000 m (6561 ft) 
``clear zone'' prior to startup in a chokepoint exercise. NMFS believes 
that these zones will effectively minimize take of marine mammals to 
the maximum extent practicable through this type of measure. Once the 
safety zones are enlarged past this point, NMFS believes detectability 
decreases notably and impracticability increases notably. The Navy 
observers will still be looking beyond the safety zone and will use the 
information to help implement the current safety zone measures.
    Comment 9: One commenter suggested that NMFS require sonar shutdown 
at 1000 m (3280 ft), instead of powerdown, and that the Navy not be 
authorized to operate sonar at all in strong surface-ducting 
conditions.
    Response: Powering down when an animal enters the 1000-m (3280 ft) 
safety zone ensures that a marine mammal will not be exposed to levels 
of sound above approximately 195 dB, the threshold established for TTS. 
Because the next powerdown is at 500 m (1640 ft), the animal would 
again not be exposed to levels above approximately 195 dB. If the 
animal were then to approach to 200 m (656 ft), it might be exposed to 
levels slightly above 195, but then sonar will shut down at 200 m (656 
ft). NMFS believes that these shutdown zones are protective enough, 
especially when balanced against the impracticability of shutting down 
at 1000 m (3280 ft).
    Comment 10: One commenter notes that the 6 dB powerdown requirement 
if

[[Page 38723]]

animals enter the 1000-m (3280-ft) safety zone still only lowers the 
sound produced to 229 dB, which is still significantly higher than the 
145-150 dB level that caused the Bahamas and Hanalei Bay strandings.
    Response: The 229 dB in this comment refers to the sound level at 1 
m (3.3 ft) from the actual sound source, whereas the 145-150 dB level 
refers to a sound level that was modeled for a particular location 
where animals may have been, based on the known locations of the 
implicated sound sources. NMFS does not expected marine mammals to 
approach within several hundred meters, much less 1 m of the sonar 
dome. Additionally, neither of the reports concluded that the listed 
sound levels 'caused'' the stranding, in Hanalei, NMFS concluded that 
sonar was a plausible, if not likely, contributor to the event. In the 
Bahamas, the Department of Defense and Department of Commerce found 
that sonar was the only possible contributory cause that could not be 
ruled out.
    Comment 11: One commenter recommended that after a shutdown the 
Navy wait 45 minutes, instead of 30, before reinitiating sonar 
operations to account for deep-diving animals.
    Response: NMFS believes that because of the fast-moving nature of 
the exercise, the vessel will have moved a significant distance from 
where the animal was seen, and, therefore, we did not include that 
measure.
    Comment 12: One commenter notes that shutdown is required by NMFS, 
in normal conditions, at 200 m. The commenter further suggests that 
within that distance of the sonar dome, the animal would have likely 
received noise levels of such intensity that mortality is almost 
certain. Additionally, the commenter notes, if the animal has gotten 
that close, the observation mitigation has obviously failed.
    Response: As noted in an above comment, if an animal were to 
approach and be detected (visually or otherwise) successive powerdowns 
would precede the shutdown, and this would prevent exposure to levels 
above those thought to potentially cause TTS. If an animal were first 
detected right at 200 m, it could potentially be exposed to levels 
approaching those thought capable of causing PTS. NMFS does not believe 
that detection of marine mammals will be 100 percent in the RIMPAC 
exercises, however because most animals will avoid the noise and 
activities surrounding the exercises, we do not anticipate animals 
approaching within 200 m of any hull-mounted sonar.
    Comment 13: One commenter recommends a mitigation measure wherein 
the Navy would be required to shut down or relocate if they detected 
beaked whales or aggregations anywhere within their sight (not just 
within the safety zone zone). They noted that NMFS recently required 
the U.S. Air Force to relocate its ordnance exercises offshore the 
Eglin Air Force Base should its fixed-wing aircraft spot any marine 
mammals or sea turtles within its orbit cycle (9.3 km).
    Response: A measure that is practicable for one activity is not 
necessarily practicable or appropriate for another. First, NMFS does 
not believe that observers will be able to recognize beaked whales 
versus another species beyond the distance of the safety zone. Second, 
NMFS believes that the required safety zones are adequate for 
minimizing take and the Navy will easily be able to implement the 
appropriate powerdowns (or avoid the animals, if preferable) in the 
presence of aggregations. RIMPAC is a highly complex and coordinated 
exercise, and shutting down or relocating in response to animals 
detected outside the safety zones is impracticable.
    Comment 14: Several commenters recommended that the Navy not 
operate sonar at night-time because animals cannot be detected as far 
out as the safety zone.
    Response: NMFS proposed a mitigation measure that would have 
required the Navy to refrain from conducting chokepoint exercises at 
night. The Navy informed NMFS that it would be unable to comply with 
that measure for the following reasons:
    Operating at night is a warfighting requirement. Night time 
conduct of ASW events is required for at least the following 
reasons:
    -Exercise realism: ASW is as much an art as a technical 
application. Commanders must learn how best to effectively employ 
the assets available. There is not a universal solution applicable 
across the board. ASW is very much dependent upon the geography, 
water conditions, available assets, time available for mission 
accomplishment and many other factors. Training for this complicated 
warfighting skill must be conducted in a variety of locations, 
situations and environmental conditions. ASW can occur at any time 
of day or night and requires that ships and aircraft be adept at 
operating in close proximity to each other in darkness and low 
visibility.
    -ASW is a lengthy and involved process. It can take many hours 
for the tactical situation to develop. It is impractical to halt a 
complicated scenario at sunset.
    -Exercise safety of other major events. Other events (e.g. 
gunnery and missile exercises) requiring more stringent safety 
measures are conducted in daylight, affording the best visibility 
for range observance. Scheduling within a relatively short exercise 
period requires ASW to take place in twilight or night conditions.
    -Darkness provides the enemy one of his greatest tactical 
advantages and therefore the need to train 24 hours a day is a 
necessary requirement to prepare U.S. forces to defend our country. 
There may be an additional risk to mammals at night, only insofar as 
there are no aerial surveys available, but that is a necessary risk 
in support of national defense.
    Comment 15: Several commenters made recommendations regarding the 
limitation of sonar activities during low visibility conditions, 
surface-ducting conditions, or chokepoint exercises including operating 
sonar at 6 dB down or shutting down sonar.
    Response: NMFS proposed a mitigation measure in which the Navy 
would be required to cease operating sonar during strong surface-
ducting conditions during the chokepoint exercises. However, the Navy 
was unable to accept that measure for the following reason:
    We already have mitigations imposed for significant surface 
ducting conditions. Our Sailors need to practice warfighting in all 
conditions. The enemy uses choke points to his tactical advantage, 
and this is the reason we need to train in a restricted water 
environment. The confluence of currents and sea state conditions in 
the Hawaiian channels make it less likely that these conditions will 
be present in the channels.
    NMFS' IHA requires the Navy to powerdown sonar by 6 dB if they 
cannot detect marine mammals out to the prescribed safety zone and in 
strong surface-ducting conditions.

Monitoring

    Comment 16: The monitoring for non-choke-point exercises is 
inadequate, in that it consists of nothing more than a single, non-
dedicated observer, watching for marine mammals while performing other 
duties on deck. It is well-established that single, non-dedicated 
observers-even if well-trained-spot only a fraction of the marine 
mammals that multiple, dedicated observers do. Additionally, another 
commenter notes that observations should be made from all platforms, 
day and night.
    Response: Though the observers on Navy vessels are not dedicated 
marine mammal observers, they are dedicated observers and do not have 
other duties on the deck. Additionally, people on all of the vessels, 
aircraft, etc. involved in the exercise have been briefed on marine 
mammals and instructed to alert the commanding officer if one is 
spotted.
    Comment 17: One commenter suggests that monitors should be 
specifically trained in marine mammal observation, extensive 
theoretical training (underwater acoustics, etc.),

[[Page 38724]]

and should have vision tests and be well rested. Another commenter 
added that observers should be independent non-Navy personnel.
    Response: At least one watchstander who has recieved training from 
a NMFS-approved instructor will be on duty at all times during the 
operation of hull-mounted tactical sonar, and all RIMPAC participants 
will be briefed on marine mammals, see an associated training video, 
and be instructed to alert the commanding officer if a marine mammal is 
sighted. Watchstanders are professional observers, and NMFS will assume 
that, due to the importance of their job, the Navy ensures that 
watchstanders are well-rested and cared for as it relates to their 
vision. NMFS does not believe that instruction in the fundamentals of 
underwater acoustics is necessary to be an effective observer, and 
therefore does not require it of observers.
    Comment 18: Several commenters note that effectiveness of vessel-
based marine mammal monitoring is low (Navy document indicates 
approximately 5 percent) and that the chance of a trained observer 
seeing a beaked whale on an ideal day for observations is approximately 
2 percent. Additionally, some commenters believe that cetaceans cannot 
be reliably detected out to the extent of the 2000-m (6561-ft) safety 
zone, especially in low visibility conditions.
    Response: NMFS acknowledges the limitations of vessel-based 
monitoring and has instituted other methods of detection in low 
visibility conditions and during chokepoint exercises. NMFS also 
requires a powerdown in low visibility conditions.
    Comment 19: Some commenters pointed out the fact that passive 
acoustic monitoring is not very effective (Navy estimates 5 percent) 
and has significant drawbacks such as the fact that it cannot detect 
non-vocalizing animals and cannot detect the distance or location of 
the animals. Another commenter suggested that passive acoustic 
monitoring should be used throughout the exercise, not just before, 
that the technology should be further developed to increase 
localization and range-finding abilities, and that specific Passive 
Acoustic Monitoring guidelines should be established.
    Response: NMFS acknowledges that passive acoustics has limitations, 
however it also adds a dimension of detection to the monitoring and 
NMFS believes that it adds value to the monitoring. Though some 
standard passive acoustic systems cannot localize or determine the 
distance to a source, NMFS notes that with towed arrays, instrumented 
ranges, active sonar, or other passive acoustic systems, better 
detection and localization of marine mammals is possible. NMFS proposed 
a mitigation measure that required the Navy to implement additional 
passive (or active) acoustic measures to use to improve detection rates 
during the RIMPAC exercises, however, the Navy was unable to comply for 
the following reasons:
    The Navy has no additional measures for detection of marine 
mammals. Passive detection will only serve to cue lookouts to more 
vigilance since localization via passive detection is not possible. 
We will use all measures available to us, including passive 
monitoring, but passive monitoring would be difficult while actively 
transmitting as the outgoing signal blanks some receive capability.
    The High Frequency Marine Mammal Monitoring System (HF/M3) 
measure is drawn from SURTASS LFA mitigation measures. SURTASS is 
very slow moving, is a very different design, and is deployed very 
differently from surface combatant vessels. The SURTASS LFA and Mid-
Frequency Antisubmarine Sonar (MFAS) are two different systems, 
deployed and operated differently with very different capabilities.
    Comment 20: Several odontocetes (beaked whales, Kogia sp., and 
others) will have a very low probability of being detected through 
aerial overflights due to their long dive times. The commenter cites 
``the effective search width for beaked whales is typically only 250-
500 m (820-1640 ft) on each side of the aircraft for aerial observers 
searching by naked eye in good to excellent sighting conditions''. The 
high winds typically present in the channels in which the chokepoint 
exercises will be conducted will reduce detection rates further.
    Response: NMFS acknowledges the limitations in detecting cryptic 
species by aerial reconnaissance and have taken them into consideration 
in our conclusions.
    Comment 21: Land-based monitoring in the Alenuihaha Channel during 
the chokepoint exercise is not adequate (monitoring will occur along 2 
km (1.1 nm) of shore, but the border of chokepoint exercise is 28 km 
(15 nm) long). Additionally, the area is gently sloping and less than 
200-m (656 ft) deep, and the animals that are thought to be more 
susceptible to high-intensity sound are not found in these areas.
    Response: Though the entire border of the exercise will not be 
monitored, NMFS believes that this mitigation adds to the detectability 
of injured or dead animals and even though it is not an area where the 
species susceptible to strandings would usually be present, if they 
were responding to sonar in the way we are concerned about, they could 
potentially go into areas we do not usually see them (milling out of 
habitat). NMFS does not believe that it would be practicable to ask the 
Navy to monitor 28 km (15 nm) of shore.
    Comment 22: The Navy should establish a public hotline for 
strandings during RIMPAC.
    Response: NMFS has established stranding response procedures, 
including a hotline, and does not want the Navy to establish another 
line, as it could only confound the response.
    Comment 23: Longterm monitoring should be conducted to assess the 
affects of RIMPAC on resident populations.
    Response: The Navy is currently coordinating long monitoring of the 
marine mammal populations within the OpArea (see Conservation Measures 
(Research), in Mitigation section, below)
    Comment 24: No information is presented on the statistical power of 
the monitoring and mitigation plan. Based on the level of monitoring 
outlined, the density of marine mammals in Hawaii, and the low 
likelihood of detecting long diving and cryptic species, the commenter 
concludes that the power to assess the presence of animals (especially 
beaked whales) to reduce impacts is low and the power to detect impacts 
if they occur is low. In addition, the prevailing direction of currents 
in Hawaii and the large number of sharks that scavenge carcasses makes 
the likelihood of dead animals stranding low.
    Response: NMFS acknowledges the challenges in detecting animals in 
order to implement mitigation measures and in detecting injured or dead 
animals in order to assess effects. NMFS has implemented several 
measures intended to increase the detectability of impacts. Aerial or 
vessel surveys will be conducted 1-2 days after an exercise to look for 
dead or injured animals. NMFS has also implemented shutdown protocols 
to use in the event of a verified stranding during RIMPAC (see 
Mitigation).
    Comment 25: One commenter recommended that NMFS require the Navy to 
conduct fewer ASW exercises to lessen the impacts.
    Response: The Navy's purpose and need for the activity (for the EA) 
is to ``implement a selected set of exercises that is combined into a 
sea control/power projection fleet training exercise in a multi-threat 
environment''. NMFS interprets the action put forth in the IHA 
application as the ``selected set'' and did not discuss an alteration 
of the proposed action with the Navy. Instead, NMFS endeavored to 
minimize impacts by limiting exercises near features

[[Page 38725]]

associated with strandings, limiting sonar output during strong 
surface-ducting conditions, requiring additional monitoring during 
chokepoint exercises, and instituting specific shutdown criteria.
    Comment 26: One commenter states that NMFS must clearly define the 
circumstances under which both the exercise and RIMPAC 2006 will be 
shut down. This commenter adds that it is particularly important that 
clear non-discretionary triggers are set for the suspension of RIMPAC.
    Response: NMFS has developed and implemented within the IHA a set 
of shutdown criteria that include specific triggers for temporary sonar 
shutdown subsequent to the verification of an uncommon stranding event, 
and indicate the framework within which NMFS will make a determination 
regarding modification, suspension, or revocation of the Navy's IHA. 
The shutdown criteria are included in the Mitigation section of this 
document.

Impact Assessment

    Comment 27: Much of the abundance data for the inshore populations 
(within 25 nm (46 km) of shore) of the main Hawaiian Islands marine 
mammals is based on the Mobley et al. (2000) aerial survey data, which 
underestimate the abundance of deep-diving/cryptic species. Mobley 
notes that the abundance estimates presented in the proposed IHA notice 
for beaked and sperm whales probably underestimate the true abundance 
by a factor of at least two to five. The commenter is concerned that 
this underestimate of abundance will be reflected in the take estimate.
    Response: If the abundance of some of these species has been 
underestimated then NMFS also may have underestimated the number of 
animals taken; accordingly, within this mathematical adjustment the 
percent of the population affected would remain the same. Since the 
increase in numbers taken is not related to a biologically important 
area, this information does not affect NMFS' negligible impact 
determination.
    Comment 28: In the case of spinner dolphins and bottlenose 
dolphins, there appears to be additional population structure within 
the main Hawaiian Islands, with genetic differentiation and no evidence 
of movements of individuals among the four main groups of islands. 
Response: The study cited for genetic differentiation of spinner 
dolphins discusses two different social systems of spinner dolphins, 
one in the main Hawaiian Islands and one in the northwestern atolls. 
The study further suggests that low diversity at a particular mDNA 
microsatellite is likely caused by geographic isolation of small 
populations that might experience some inbreeding. The study does not 
suggest different sub-populations within the main Hawaiian Islands or, 
therefore, within the Hawaiian OpArea. The cited bottlenose dolphin 
study revealed that there may be genetically differentiated populations 
stratified by both site fidelity to a particular island, and in one 
case, depth. Because the RIMPAC exercises are distributed throughout 
the islands and 2-24 hours in duration each, because the potentially 
genetically differentiated populations are not known to be limited to 
an area smaller than a whole island, and because of the high 
detectability of bottlenose dolphins (which increases mitigation 
effectiveness), NMFS does not expect this additional information to 
affect our negligible impact determination.
    Comment 29: One commenter notes that several species are 
genetically differentiated between the Hawaiian Islands population and 
the tropical Pacific population
    Response: As described, the Hawaiian populations extend to an 
unknown distance beyond the EEZ, so this observation does not affect 
the negligible effect determination.
    Comment 30: The additional mitigation measures do not take into 
account the cumulative and synergistic effects of multiple noise 
sources being employed at any one time or over time. Such effects 
should be addressed before any authorization is issued.
    Response: The Navy's model sums the received energy from multiple 
sources and calculates the SEL around the sonar sources. This SEL, 
which is an energy metric, does take into account the effects of 
multiple sources over time. The Navy's model does incorporate synergism 
to some degree, as conditions in the model are based on nominal 
conditions calculated from a generalized digitalized monthly average, 
which includes surface-ducting conditions. Though synergistic 
possibilities exist that are not addressed by the model, the Navy has 
incorporated several conservative features into the model that help 
balance other inadequacies of the model (such as the fact that animals 
are assumed to remain stationary in the presence of the ASW activities 
and the fact that animals are assumed to be located at the loudest 
depth within the water column).
    Comment 31: Most of the papers cited to support the evaluation of 
the Level B harassment behavioral threshold involved either sinusoidal 
tones or impulses. When developing thresholds for mid-frequency sonar, 
NMFS should use studies that employ complex, sonar-like signals.
    Response: In this regard, NMFS is constrained by the available 
science. The one known incident (Haro Strait, see Sub-TTS Behavioral 
Threshold section) in which cetaceans were actually exposed to mid-
frequency tactical sonar signals from naval vessels, and scientists, 
having some information about exposure conditions (including duration) 
were able to estimate their received level in terms of sound exposure 
level has been included in our development of the 173-dB threshold.
    Comment 32: Regarding the estimation of PTS onset relative to TTS 
levels used in the development of the Level A Harassment threshold, the 
Navy incorporates the maximum recoverable TTS that humans (and cats, in 
one study) can recover from without permanently damaging their hearing. 
The commenter points out that both humans and cats are highly visually 
adapted species (though cats less so than humans), and from the 
relationship between their different recoverable TTS levels he deduces 
that animals that are more dependent on sound cues are less able to 
recover from extreme TTS. The commenter further asserts that it might 
easily follow that cetaceans that rely almost exclusively on acoustical 
cues would be even less likely to recover from extreme TTS. Through 
further alternative interpretations of the data that the Navy used to 
estimate the onset of PTS, the commenter suggests that PTS onset could 
be estimated at 210 dB or as low as 200 dB.
    Response: The extrapolation that the Navy uses to estimate PTS 
onset from known TTS levels consists of several discrete steps, and in 
each of these separate calculations the Navy has built in conservative 
approximations to help offset the lack of taxa-specific data and other 
data gaps, such as that which the commenter highlights. Additionally, 
Navy researchers have exposed captive dolphins to sound levels in 
certain conditions to exposures exceeding 220 dB peak and 200 dB SEL 
and been unable to elicit TTS, much less PTS.
    Comment 33: Several commenters note different sound levels (145-165 
SPL, 174 SEL) cited in the Bahamas and Hanalei Bay Stranding reports 
and assert that NMFS should base our Level B Harassment behavioral 
threshold on these numbers.
    Response: The sound levels cited in these reports are, for the most 
part, the modeled received sound at a particular location, based on the 
known locations of different sound sources present near the time of the 
stranding event and the

[[Page 38726]]

best guess of the sound speed profile in the area based on available 
environmental data. While this information is valuable for many 
reasons, we do not know where any of the animals were actually located 
in relation to the known sound sources when the behavioral or 
physiological response that led to either of these strandings was 
triggered. The Level B Harassment behavioral threshold that NMFS has 
chosen is based primarily on two studies and one incident in which 
actual received levels were measured and/or we know the source level 
and the approximate distance of the animal from the sound source 
leading to relatively precise modeling estimates.
    Comment 34: NMFS has not considered the full breadth of available 
information on bubble growth in its potential effects analysis. For 
example, some researchers suggest that gas bubbles could be activated 
in supersaturated marine mammal tissue on brief exposure to sounds of 
150 dB (rms) re 1 miPa or lower and then grow significantly, causing 
injury as the animal rises to the surface. Further, the commenter 
mentions the investigation of the 2002 Canary Islands strandings, whose 
findings concerning fat and gas emboli were recently published, but not 
mentioned in our analysis.
    Response: Though NMFS did not mention the specific results cited 
above in the discussion of bubble growth in the proposed IHA, adequate 
coverage of the topic was provided through a summary discussion of 
acoustically mediated bubble growth, which discussed the 
destabilization of stable bubbles by high-level sound exposures such 
that bubble growth occurs through static diffusion of gas out of the 
tissues, the evolution of nitrogen bubbles through rapid ascent to the 
surface, and rectified diffusion. Additionally, based on the available 
science, the exact mechanisms for bubble growth are unknown, and the 
predicted received levels to induce bubble growth are estimated to 
exceed those required to induce TTS. NMFS believes that the mitigation 
measures designed to avoid serious injury or mortality and effect the 
least practicable adverse impact also function to minimize the chances 
of bubble growth.
    Comment 35: NMFS' injury threshold does not reflect non-auditory 
physiological impacts, as from stress and from chronic exposure during 
development.
    Response: NMFS acknowledges the importance of potential 
physiological effects of mid-frequency tactical sonar on marine mammals 
and they are addressed in this document. However, information regarding 
the sound levels, frequencies, and duration/repetition conditions these 
types of effects result in is unavailable and, therefore, cannot 
contribute to the development of the injury threshold.
    Comment 36: NMFS should use a dual threshold (SPL and SEL, not just 
SEL) for injury, as a 2003 Office of Naval Research report suggests 
that peak power may have more to do with the way beaked whales respond 
to sound (and potentially strand).
    Response: Because of the equal energy line applied by Finneran 
(2002) to the TTS data of several researchers, NMFS believes that SEL 
can be effectively used to predict when TTS and PTS (from 
extrapolation) will occur in marine mammals. There is little data 
relating to mid-frequency tactical sonar in particular, however, the 
larger body of data related to high-intensity sound in general suggests 
that context and SPL are also important in how animals behaviorally 
react to sound. While SEL may not be the only metric important in 
predicting the response of marine mammals to sound, NMFS chose the 
behavioral threshold for this authorization based on three studies/
events thought to be most closely representative of how mid-frequency 
sonar affects marine mammals for which SEL exposures are available. 
Additionally, the pulse length and signal types produced by RIMPAC are 
known (vs. explosions) and NMFS believes that in this particular case, 
SEL is an appropriate metric for the behavioral harassment threshold. 
NMFS is currently developing acoustic criteria, which may include dual 
critieria, but the wide-ranging evidence regarding at what levels 
marine mammals behaviorally respond to high-intensity sound has made 
the behavioral threshold part of that process difficult both in terms 
of metrics and absolute numbers.
    Comment 37: For the SURTASS LFA sonar authorization, the Navy used 
a study that showed resonance damage to small mammals (submerged) at 
205 dB to establish their proposed Level A injury threshold. Why was 
that threshold not used in this authorization?
    Response: NMFS believes that extrapolation to PTS from the specific 
marine mammal TTS onset data is the more appropriate way to establish 
the threshold. The size and nature of the air spaces within small 
mammal ears may affect the way sound affects the tissues of the ear 
such that these results are not as applicable to marine mammals.
    Comment 38: TTS is physiological damage that can last from minutes 
to days, and can increase the chances of being injured or killed. TTS 
should be considered Level A Harassment.
    Response: TTS may be considered to be an adaptive process 
(analogous to the dark adaptation in visual systems) wherein sensory 
cells change their response patterns to sound. Tissues are not 
irreparably damaged with the onset of TTS, the effects are temporary 
(particularly for onset-TTS), and NMFS does not believe that this 
effect qualifies as an injury. Therefore TTS-onset is treated as the 
upper bound of Level B Harassment.
    Comment 39: For the development of the TTS threshold, the Navy's 
extrapolation of data from bottlenose dolphins and belugas to all 
cetaceans is not justifiable because they do not have the most 
sensitive hearing of all cetaceans and some studies suggest that 
hearing sensitivity may be variable as a function of signal production 
and/or other parameters.
    Response: The absolute hearing sensitivity at the frequency of 
tactical, mid-frequency sonar is similar for most odontocetes that have 
been tested. Additionally, onset-TTS values used for the calculation of 
PTS onset represent the most sensitive of the animals tested. 
Presumably, any modulation of sensitivity that served to protect the 
cetacean auditory system from overexposure to noise would be activated 
by intense noise exposure. It would be expected to operate, if it in 
fact exists, in captive marine mammals involved in the TTS studies as 
well as animals exposed to loud noise in the wild. There is no 
empirical comparative data on these phenomena with which to modify/
adjust the TTS onset or growth estimates. Comment 40: The Finneran 
equal energy line applied to multiple TTS datasets was used to justify 
the 195 dB TTS threshold (and by extrapolation, the 215 PTS threshold) 
in this authorization. This line could have justifiably been drawn at 
190 dB (without giving such weight to the single Natchtigall point), 
and would have been more conservative.
    Response: While acknowledging the limitations of current data and 
the existing criticisms of an equal energy approach in the terrestrial 
mammalian literature at this time, NMFS believes that the 195-SEL equal 
energy line is a reasonable interpretation of the current data at this 
time. Both TTS onset and the estimation of PTS onset as a demarcation 
of physical injury have several precautions built into the assumptions. 
The equal-energy line through the existing cetacean TTS data is not a 
least-squares regression of the data but rather an expression of 
pressure

[[Page 38727]]

magnitude of exposure as a function of duration. That the long duration 
exposures from Nachtigall et al. fall so close to this line (they are 
not used to derive it) is one of a number of arguments in favor of the 
use of SEL as a means of comparing TTS-onset across extremely variable 
exposure conditions. Finally, the 195-dB SEL line was selected based on 
the empirical measures of TTS-onset for 195 dBrms 1-s exposures and 
extrapolated to other exposures of variable sound pressure magnitude 
and duration using the equal energy relationship.
    Comment 41: Several commenters suggest that the animals used in the 
studies the Navy used to develop their proposed TTS threshold were old 
and test-habituated, and that studies involving younger, less test-
habituated animals should be given more weight. Another commenter noted 
that the animals used in the TTS study may not adequately represent the 
range of variation within their own species.
    Response: NMFS acknowledges that the test-animals may not fully 
represent the range of hearing responses across multiple taxa, within 
their own species, or in some cases even within individuals whose 
sensitivity may change over time however, we have used the best science 
available to develop these thresholds. Also, though NMFS believes that 
habituation to exposure may affect how animals respond to noises in a 
behavioral context, but that from a sensorineural point of view there 
is likely less dependence on exposure history. NMFS is aware of some 
data on terrestrial mammals indicating a ``toughening'' of auditory 
systems repeatedly exposed to noise, but notes that such data are 
generally unavailable for marine mammals but not indicated in the 
exposure sequences of subjects that have been tested. In fact, some 
data exist indicating a slight apparent improvement in the hearing 
sensitivity (lower thresholds over time) of marine mammals at a 
particular sound frequency for which TTS is tested, likely as a result 
of the increased relevance of those particular signals to the animals 
in the context of food-reward tasks.
    Comment 42: Pinniped data should have been used in the development 
of the threshold.
    Response: NMFS does not anticipate take of pinnipeds as a result of 
this action and, therefore, did not consider the incorporation of 
pinniped data into the thresholds (or the development of separate 
pinniped thresholds) necessary.
    Comment 43: A recent study of threshold shift in pinnipeds found 
that the amount of hearing loss an animal experiences does not increase 
linearly with the energy it receives. As the energy intensifies, its 
rate of hearing loss increases, to such a degree that projections of 
permanent threshold shift according to traditional, linear models are 
likely to result in underestimates of harm. The Navy should lower its 
threshold.
    Response: Kastak et al (2005) note the non-linear growth of TTS for 
relatively small magnitude shifts (< 6dB) and the innadequacy of a 
linear model using only these data in predicting the growth of TTS with 
exposure level for a wider range of exposures. It is well known that 
the TTS growth function is sigmoidal and thus it is misleading to 
describe it solely based on exposures that generate only small-
magnitude TTS (where the slope of the growth function is relatively 
shallow). For a wide range of exposures, however, there is a steeper, 
linear portion of the sigmoidal function and a fairly consistent 
relationship between exposure magnitude and growth of TTS. The slope of 
this relationship is relatively well-known for humans (on the order of 
1.6 dB TTS/dB noise (Ward et al., 1958; 1959)). While it is not well-
understood for marine mammals (because studies to date have yet to 
induce sufficiently large TTS values to properly assess it), the slope 
of this portion of the function predicted by the Kastak et al (2005) 
data fit with the curvilinear approximation (based on Maslen, 1981) was 
found to be comparable. Therefore, estimations of PTS from TTS onset 
that use a linear growth function with the steepest slope from a 
curvilinear function are very likely appropriate and in fact a 
conservative approximation, based on the information available at this 
time.
    Comment 44: The 173-dB behavioral threshold is not supportable, as 
significant behavioral changes have been demonstrated in a controlled 
exposure experiment (Nowacek et al., 2004) at 154 dB SEL. It is not 
appropriate to use the 25th percentile results of the Finneran study 
(173 dB), as the captive animals in that study cannot adequately 
represent the responses of wild animals. Alternatively, NMFS received 
one comment in support of the issuance of the IHA, but that commenter 
believed that the 190-dB behavioral threshold was supported, not the 
190-dB threshold.
    Response: As discussed in the text, NMFS used the three examples 
(Finneran and Schlundt, 2004, Nowacek et al., 2004; and NMFS Haro 
Strait analysis) of cetacean responses to high intensity sound that we 
believe are the most predictive for marine mammal responses to tactical 
sonar to develop the threshold. Generally, NMFS interprets the received 
SELs in these studies as approximately 50 percent disturbance = 190 dB 
SEL (Finneran), approximately maximum SEL:160 dB (Nowacek), and 
approximately 165-175 dB SEL (Haro Strait). Where using a single 
threshold, instead of the likely more appropriate but currently unknown 
dose-response sigmoidal relationship, NMFS acknowledges that some 
animals exposed above the threshold may not be harassed by the sound 
and, conversely, some animals exposed to a sound below the threshold 
may be harassed. Therefore, NMFS believes that an appropriate threshold 
is a number somewhere between the lowest and highest mid-frequency 
signal exposure levels to which animals have demonstrated profound 
behavioral disturbance, which is why we chose 173 dB SEL for this 
authorization.
    Comment 45: NMFS' analysis of effects should include more 
information on the avoidance behavior and behavioral response data of 
mysticetes to high-intensity sound.
    Response: The majority of data addressing mysticete avoidance and 
behavioral responses to sound relates to low frequency sound. Because 
of differences in how animals react to these two different types of 
sound and differences in how these sounds propagate, the Navy and NMFS 
limited the analysis to primarily mid-frequency/tactical sonar-type 
data. However, one of three datum used to develop the behavioral 
harassment threshold was derived from right whale responses (Nowachek).
    Comment 46: The model the Navy uses to calculate take is flawed 
because it does not take into consideration reverberation, surface-
ducting, or sources above 205 dB.
    Response: The model does indirectly incorporate surface-ducting, as 
conditions in the model are based on nominal conditions calculated from 
a generalized digitalized monthly average. Though the model does not 
consider reverberations, these effects are generally at received levels 
many orders of magnitude below those of direct exposures (as 
demonstrated in the Haro Strait analysis) and thus contribute 
essentially nothing to the cumulative SEL exposure. The Navy did not 
include sources below 205 dB in its model because sound is expected to 
attenuate to below 173 dB within 100 m (328 ft) around these sources 
(animals are expected to avoid the dynamic exercise

[[Page 38728]]

at that distance and/or monitors are largely expected to detect and 
shut down sonar (within 200 m (656 ft))) and because larger sources 
will usually be operating in the vicinity, adding to the likelihood of 
avoidance.

NEPA Compliance

    Comment 47: The Navy should revise the EA based on the findings of 
the final Hanalei Bay report to reflect ``significant new 
information''.
    Response: Though the final Hanalei report was not published when 
the Navy issued the April draft of its EA and the event was not 
discussed in the necessary detail in that draft, NMFS considered the 
event in more detail, as demonstrated in both this final IHA notice and 
the associated Finding of No Significant Impact (FONSI) .
    Comment 48: The Navy suggests at points in the EA that its analysis 
of extraterritorial activities, those activities that would take place 
outside U.S. territorial waters, was prepared under the authority of 
Executive Order 12114 rather than under NEPA. The Navy's position on 
the scope of the review is inconsistent with the statute. For NMFS, 
adopting such a position is clearly insupportable, given that the 
Federal action to which its NEPA review applies, the decision to 
authorize RIMPAC, takes place entirely within the territory of the U.S. 
NMFS should indicate its derogation from the Navy's EA on this point.
    Response: Pursuant to NOAA Administrative Order 216-6, NMFS applies 
NEPA in the EEZ, and has complied with NEPA for this action.
    Comment 49: One commenter believes that the Navy's purpose and need 
is too narrow.
    Response: The Navy's stated purpose is to ``implement a selected 
set of exercises that is combined into a sea control/power projection 
fleet training exercise in a multi-threat environment''. NMFS does not 
believe that this stated purpose is inherently too narrow.
    Comment 50: The Navy does not do an adequate alternatives analysis. 
The alternatives consist of the preferred alternative, the no action 
alternative, and previously considered alternatives. The Navy does not 
consider alternate geographical locations or any other alternatives. 
NMFS should not adopt the EA.
    Response: For the purposes of NMFS' federal action--the issuance of 
an MMPA authorization--the alternatives are adequate: no action, 
preferred action (ASW with added mitigation), and the previously 
considered alternative (ASW with no added mitigation).
    Comment 51: An overarching concern is the blanket exclusion of fish 
and invertebrates from consideration [in the EA] in terms of acoustic 
impacts.
    Response: The Navy provided a supplemental analysis of the effects 
of mid-frequency sonar on fish and NMFS has included it in the FONSI.
    Comment 52: The Navy's EA did not adequately consider cumulative 
effects. NMFS must assess the potential for synergistic adverse 
effects, as from noise in combination with ship stripes, properly 
assess the cumulative impacts of holding biannual RIMPAC exercises in 
the same areas off Hawaii, and consider whether individual naval 
exercises in the Hawaiian Islands Operating Area and other activities 
could combine with RIMPAC to produce a significant effect.
    Response: NMFS acknowledges the need for additional analysis of 
cumulative effects in the NEPA analysis and has addressed cumulative 
effects in the FONSI
    Comment 53: With regard to noise-producing activities the Navy must 
describe source levels, frequency ranges, duty cycles, and other 
technical paramenters relevant to determining potential impacts on 
marine life.
    Response: NMFS requested this information early in the process and 
the Navy informed NMFS that the majority of the information was 
``classified''.
    Comment 54: For Data Quality Act compliance, the models used in 
this analysis need to be available to the public.
    Response: MatLab is a commercially available program. CASSGRAB is 
available to the public from the Federal Government through leasing 
arrangements. The other components of the Navy's model are not 
published and can be discussed with the Navy.
    Comment 55: Several commenters were concerned that NMFS could not 
satisfy the criteria necessary to issue a Finding of No Significant 
Impact.
    Response: NMFS issued a FONSI on June 27, 2006, addressing all the 
required criteria.

MMPA Compliance

    Comment 56: Pursuant to the MMPA (16 U.S.C. 1371(a)(5)(D)(i)), an 
IHA can only be granted for harassment, not serious injury or 
mortality. NMFS cannot say with confidence that serious injury or 
mortality will not occur incidental to this action, especially during 
the chokepoint exercises, which present four of five conditions for 
heightened risk: (1) the use of tactical sonar, (2) in places where as 
many as three species of beaked whale may occur, (3) areas with steep 
bathymetry, and (4) areas that offer surface-ducting conditions.
    Response: NMFS has required a suite of mitigation measures in the 
IHA that reduces the likelihood of a stranding resulting from the 
RIMPAC ASW activities. However, several points that were emphasized in 
the public comments (i.e., the difficulty (in ideal conditions) of 
detecting beaked whales, which have been among the species in most of 
the strandings associated with sonar, and the fact that choke-point 
exercises will be conducted both at night and in surface-ducting 
conditions) and the published conclusions of the Hanalei Bay melon-
headed whale report do not allow NMFS to rule out the possibility of a 
stranding resulting from the RIMPAC ASW activities. Consequently, NMFS 
has included specific shutdown criteria (see Mitigation and Monitoring, 
above), which are intended to ensure MMPA compliance. These criteria 
require the Navy to temporarily cease operating sonar in a designated 
area when a stranding is verified during the RIMPAC ASW exercise. NMFS 
will then conduct an investigation, and if NMFS finds that the Navy's 
activities may have contributed to the stranding, NMFS will modify, 
revoke, or suspend the IHA.
    Comment 57: NMFS can not reach a negligible impact determination 
for beaked whales as the activity is projected to affect over 16 
percent of each population of beaked whales and the mitigation measures 
are know to be ineffective due to the low detectability of beaked 
whales.
    Response: As discussed in more detail in the Negligible Impact 
Determination section, NMFS does not believe that over 16 percent of 
each beaked whale species will be harassed by these activities. NMFS 
believes that the initial take numbers generated by the Navy's model 
are overestimates, that the mitigation measures will reduce that 
percent somewhat (especially through measures that don't depend on 
detection, such as exclusion zones and circumstantial powerdowns), and 
that the beaked whale populations extend past the EEZ (make sure 
spelled out first time in document), which means that a smaller percent 
of the population will be affected by the activities within the EEZ 
that what was modeled. This, coupled with the temporary nature of the 
exercise and the implementation of the new shutdown criteria, leads 
NMFS to believe the activity will have a negligible impact on beaked 
whale populations.
    Comment 58: NMFS cannot make negligible impact determinations for 
species other than beaked whales

[[Page 38729]]

because the portions of the populations affected by the activity are 
too high.
    Response: As mentioned in the prior response and in the Negligible 
Impact Determination section, NMFS believes that the actual portion of 
the populations affected by the RIMPAC exercises is significantly 
smaller than modeled number of individuals taken divided by the 
estimated abundance in the EEZ. In addition to the reasons stated in 
the previous response, the percent of the population affected is even 
smaller for animals with significantly larger densities inshore than 
offshore (due to the 25-km (13.5-nm) exclusion zone) and for animals 
with large average group sizes or large body size (far more detectable 
through monitoring). Tables 3 and 4 discuss what factors were 
considered in the negligible impact determination.
    Comment 59: NMFS must also consider other RIMPAC exercises that 
might impact marine mammals that are intertwined with anti-submarine 
warfare exercises, such as air-to-surface gunnery exercises, mine 
countermeasures, etc.
    Response: The Navy applied for an authorization for take of marine 
mammals incidental to ASW exercises. As described in the application, 
the ASW exercises are discrete exercises.
    Comment 60: NMFS' notice states that RIMPAC will not have an 
unmitigable adverse impact on the availability of the species or stocks 
for subsistence uses. The notice should clarify that only the 
subsistence hunting of marine mammals by Alaska natives is considered 
in the findings under either 101(a)(5)(A) or 101(a)(5)(D) of the MMPA.
    Response: After reviewing the statute, NMFS believes the commenter 
is correct and has removed the reference to that finding from the 
appropriate documents.Other Comments
    Comment 61: Foreign vessels and crews cannot avail themselves of an 
IHA for the harassment of marine mammals in the U.S. Exclusive Economic 
Zone because section 101(a)(5)(D) of the MMPA is available only to 
``citizens of the United States.''
    Response: This doesn't have an associated comment-think it belongs 
one or two pages up where there's no response to a comment on this 
issue. The U.S. Navy is the applicant for purposes of this IHA for 
RIMPAC 2006 exercises and qualifies as a U.S. citizen under NMFS 
regulations. NMFS has issued the IHA to the Navy, which is hosting the 
exercises. As the holder of the IHA, the Navy is responsible for 
implementing the terms and conditions of the IHA, which requires that 
all participants in RIMPAC ASW activities abide by the IHA's mitigation 
and monitoring requirements. The Navy has indicated that all foreign 
vessels participating in RIMPAC 2006 will be under the Operational 
Control (OPCON) of Commander, U.S. THIRD Fleet in his capacity as 
Officer Conducting the Exercise (OCE) and Commander, Combined Task 
Force (CCTF) RIMPAC. As such, all forces assigned, including foreign 
vessels and aircraft operating under CCTF RIMPAC OPCON, are required to 
comply with the environmental mitigation measures spelled out in Annex 
L to the RIMPAC 2006 OPORDER as a condition of participating in the 
exercise. Under Annex L and two other annexes, all vessels, including 
foreign ships, are required to make sonar use reports in the daily 
operational summary.
    Comment 62: NMFS sets the injury threshold at 215 dB (for PTS); yet 
we say that ``some marine mammals may react to mid-frequency sonar, at 
received levels lower than those thought to cause direct physical harm, 
with behaviors that may, in some circumstances, lead to physiological 
harm, stranding, or, potentially, death''. If this is the case, the 
Level A harassment threshold should be lower.
    Response: Thresholds represent sound levels at which NMFS predicts 
marine mammals are likely to be harassed in a certain way or to a 
certain level. The behavioral Level B harassment threshold represents 
the level at which NMFS believes marine mammals are likely behaviorally 
harassed. Within the range of potential behavioral responses rising to 
the level of harassment, a small subset of the animals exposed may 
respond behaviorally or physiologically in a way that leads to a 
stranding. Such an extreme reaction by some animals does not 
necessarily justify the establishment of a general threshold, but 
instead an awareness of the possibility of this response and 
implementation of mitigation measures to address it, such as those 
contained in this IHA (e.g., 25-km (13.5 nm) exclusion zone, extra 
monitoring, etc.). Additionally, the exact mechanisms that lead to a 
stranding are not well understood, and it is believed that there are 
often other (unknown) contributing factors involved. NMFS does not 
believe it is appropriate to use sound levels that represent the onset 
of the behavioral disturbance to also represent the onset of injury 
when other contributing factors may be necessary to get to injury from 
the initial behavioral disturbance.
    Comment 63: The Navy should keep, and make available to NMFS if a 
stranding occurs, a detailed log of sonar use. The detailed report 
required to NMFS should be made available to NMFS within a given amount 
of time after RIMPAC is completed.
    Response: The Navy keeps very specific records of when and where 
sonar is operated. The Navy will make both classified ``secret' and 
unclassified reports to NMFS after RIMPAC. In the event of a stranding, 
the Navy will coordinate with NMFS to provide the needed information 
regarding the positioning of the operating sonar within the OpArea. 
Unclassified reports from the Navy are immediately available to the 
public. Classified reports will be made available as they are 
unclassified.
    Comment 64: The commenter is concerned that the RIMPAC proposal is 
using the Navy's draft EIS for the USWTR proposal even while the 
assumptions, methodologies, and substantiating information are still in 
draft and are still under review.
    Response: Some of the information in the Navy's draft EIS for USWTR 
constitutes the best available science, even if it is still in review.
    Comment 65: The commenter is troubled that conservation 
organizations need to continually expend their resources and energies 
attempting to stem the destruction of marine habitat by the U.S. Navy. 
The commenter states that the ``burden of proof'' falls upon those who 
are attempting to conserve marine mammal habitat, and not the U.S. 
Navy, who are proposing assaults and compromises to the environment.
    Response: NMFS cannot address this issue.
    Comment 66: NMFS received approximately 120 general comments of 
opposition within the comment period, and approximately 100 additional 
comments of general opposition after the comment period closed. Many of 
the commenters did not think that NMFS should authorize the Navy to 
injure or kill the animals and many expressed the thought that we 
should avoid impacts to marine mammals.
    Response: NMFS appreciates the outpouring of concern for the well-
being of the marine mammals around the Hawaiian Islands. As a 
clarification, NMFS has not authorized the injury or mortality of 
marine mammals and has including mitigation and monitoring measures to 
reduce the potential for injury or mortality, as well as instituting 
stranding shutdown protocols for use in the event of any stranding. 
Further, though NMFS does not ask for protective measures meant to 
entirely avoid disturbance of marine mammals, which would preclude the 
need for an authorization, we have included measures intended to affect 
the least

[[Page 38730]]

practicable adverse impact on the species.

Mitigation, Monitoring, and Reporting

    The Navy has requested an IHA from NMFS for the take, by 
harassment, of marine mammals incidental to RIMPAC ASW exercises in the 
OpArea. Section 101(a)(5)(D) of the MMPA, the section pursuant to which 
IHAs are issued, may not be used to authorize mortality or serious 
injury leading to mortality. The Navy's analysis of the RIMPAC ASW 
exercises concluded that no mortality or serious injury leading to 
mortality would result from the proposed activities. However, NMFS 
believes that some marine mammals may react to mid-frequency sonar, at 
received levels lower than those thought to cause direct physical harm, 
with behaviors that may lead to physiological harm, stranding, or, 
potentially, death. Therefore, in processing the Navy's IHA request, 
NMFS has required additional mitigation and monitoring than originally 
proposed in the Navy's application, which is intended to ensure that 
mortality or serious injury leading to mortality does not result from 
the proposed activities.
    In any IHA issued there is the requirement to supply the ``means of 
effecting the least practicable [adverse] impact upon the affected 
species.'' NMFS' determination of ``the least practicable adverse 
impact on the affected species'' includes consideration of personnel 
safety, practicality of implementation, and impact on the effectiveness 
of military readiness activities. While NMFS' proposed mitigation and 
monitoring requirements discussed below are intended to effect the 
``least practicable adverse impact'', they are also designed to ensure 
that no mortality or serious injury leading to mortality occurs, so 
that an IHA may be legally issued under the MMPA.

Changes Made in the IHA Since the Proposed IHA was published in the FR

    Three changes have occurred in the authorization since the proposed 
IHA was published in the Federal Register: (1) a mitigation measure was 
added wherein during chokepoint exercises the Navy must ensure that a 
2000 m (6561 ft) (vs. 1000 m (3280 ft) in non-chokepoint exercises) 
radius is clear of marine mammals prior to startup of sonar; (2) 
stranding shutdown protocols were included in the IHA; and (3) the Navy 
requested they be allowed to conduct 6.5 hours of sonar operations 
within the part of the PMRF that falls within 25 km (13.5 nm) of the 
200-m (656-ft) isobath, and NMFS subsequently made the requested 
modification to the IHA and added a mitigation measure that requires 
the Navy abide by the applicable existing chokepoint mitigation 
measures when conducting these activities. These changes are addressed 
in more detail in the ``Additional Mitigation, Monitoring, and 
Reporting Measures Required by NMFS'' section below.

Standard Operating Procedures Proposed in Navy Application

    Navy shipboard lookout(s) are highly qualified and experienced 
observers of the marine environment. Their duties require that they 
report all objects sighted in the water to the Officer of the Deck 
(e.g., trash, a periscope, a marine mammal) and all disturbances (e.g., 
surface disturbance, discoloration) that may be indicative of a threat 
to the vessel and its crew. There are personnel serving as lookouts on 
station at all times (day and night) when a ship or surfaced submarine 
is moving through the water.
    Navy lookouts undergo extensive training in order to qualify as a 
watchstander. This training includes on-the-job instruction under the 
supervision of an experienced watchstander, followed by completion of 
the Personal Qualification Standard program, certifying that they have 
demonstrated the necessary skills (such as detection and reporting of 
partially submerged objects). In addition to these requirements, many 
Fleet lookouts periodically undergo a 2-day refresher training course.
    The Navy includes marine species awareness as part of its training 
for its bridge lookout personnel on ships and submarines. Marine 
species awareness training was updated in 2005 and the additional 
training materials are now included as required training for Navy 
lookouts. This training addresses the lookout's role in environmental 
protection, laws governing the protection of marine species, Navy 
stewardship commitments, and general observation information to aid in 
avoiding interactions with marine species. Marine species awareness and 
training is reemphasized by the following means:
    Bridge personnel on ships and submarines-Personnel utilize marine 
species awareness training techniques as standard operating procedure, 
they have available the ``whale wheel'' identification aid when marine 
mammals are sighted, and they receive updates to the current marine 
species awareness training as appropriate.
    Aviation units-All pilots and aircrew personnel, whose airborne 
duties during ASW operations include searching for submarine 
periscopes, report the presence of marine species in the vicinity of 
exercise participants.
    Sonar personnel on ships, submarines, and ASW aircraft-Both passive 
and active sonar operators on ships, submarines, and aircraft utilize 
protective measures relative to their platform.
    The Environmental Annex to the RIMPAC Operational Order mandates 
specific actions to be taken if a marine mammal is detected and these 
actions are standard operating procedure throughout the exercise.
    Implementation of these protective measures is a requirement and 
involves the chain of command with supervision of the activities and 
consequences for failing to follow orders. Activities undertaken on a 
Navy vessel or aircraft are highly controlled. Very few actions are 
undertaken on a Navy vessel or aircraft without oversight by and 
knowledge of the chain of command. Failure to follow the orders of 
one's superior in the chain of command can result in disciplinary 
action.

Operating Procedures

    The following procedures are implemented to maximize the ability of 
operators to recognize instances when marine mammals are close aboard 
and avoid adverse effects to listed species:
    Visual detection/ships and submarines-Ships and surfaced submarines 
have personnel on lookout with binoculars at all times when the vessel 
is moving through the water. Standard operating procedure requires 
these lookouts maintain surveillance of the area visible around their 
vessel and to report the sighting of any marine species, disturbance to 
the water's surface, or object (unknown or otherwise) to the Officer in 
Command.
    Visual detection/aircraft-Aircraft participating in RIMPAC ASW 
events will conduct and maintain, whenever possible, surveillance for 
marine species prior to and during the event. The ability to 
effectively perform visual searches by participating aircraft crew will 
be heavily dependent upon the primary duties assigned as well as 
weather, visibility, and sea conditions. Sightings would be immediately 
reported to ships in the vicinity of the event as appropriate.
     Passive detection for submarines - Submarine sonar operators will 
review detection indicators of close-aboard marine mammals prior to the 
commencement of ASW operations involving active mid-frequency sonar.
    When marine mammals are detected close aboard, all ships, 
submarines, and aircraft engaged in ASW would reduce

[[Page 38731]]

mid-frequency active sonar power levels in accordance with the 
following specific actions:
    (1) Helicopters shall observe/survey the vicinity of an event 
location for 10 minutes before deploying active (dipping) sonar in the 
water. Helicopters shall not dip their sonar within 200 yards of a 
marine mammal and shall secure pinging if a marine mammal closes within 
200 yards after pinging has begun.
    (2) Note: Safety radii, power-down, and shut-down zones proposed by 
the Navy have been replaced with more conservative measures required by 
NMFS and are discussed in the next section.
    The RIMPAC Operational Order Environmental includes specific 
measures, including the measures required by NMFS' IHA, that are to be 
followed by all exercise participants, including non-U.S. participants.
    The Navy proposes that training be provided to exercise 
participants and NOAA officials before and during the in port phase of 
RIMPAC (26-30 Jun 06). This will consist of exercise participants (CO/
XO/Ops) reviewing the C3F Marine Mammal Brief, available OPNAV N45 
video presentations, and a NOAA brief presented by C3F on marine mammal 
issues in the Hawaiian Islands. The Navy will also provide the 
following training for RIMPAC participants:
    (1) NUWC will train observers on marine mammal identification 
observation techniques
    (2) Third fleet will brief all participants on marine mammal 
mitigation requirements
    (3) Participants will receive video training on marine mammal 
awareness
    (4) Navy offers NOAA/NMFS opportunity to send a representative to 
the ashore portion of the exercise to address participants and/or 
observe training.

Conservation Measures (Research)

    The Navy will continue to fund ongoing marine mammal research in 
the Hawaiian Islands. Results of conservation efforts by the Navy in 
other locations will also be used to support efforts in the Hawaiian 
Islands. The Navy is coordinating long term monitoring/ studies of 
marine mammals on various established ranges and operating areas:
    (1) Coordinating with NMFS to conduct surveys within the selected 
Hawaiian Islands Operating Area as part of a baseline monitoring 
program.
    (2) Implementing a long-term monitoring program of marine mammal 
populations in the OpArea, including evaluation of trends.
    (3) Continuing Navy research and Navy contribution to university/
external research to improve the state of the science regarding marine 
species biology and acoustic effects.
     (4) Sharing data with NMFS and the public, via the literature, for 
research and development efforts.
    The Navy has contracted with a consortium of researchers from Duke 
University, University of North Carolina at Wilmington, University of 
St. Andrews, and the NMFS Northeast Fisheries Science Center to conduct 
a pilot study analysis and develop a survey and monitoring plan that 
lays out the recommended approach for surveys (aerial/shipboard, 
frequency, spatial extent, etc.) and data analysis (standard line-
transect, spatial modeling, etc.) necessary to establish a baseline of 
protected species distribution and abundance and monitor for changes 
that might be attributed to ASW operations on the Atlantic Fleet 
Undersea Warfare Training Range. The Research Design for the project 
will be utilized in evaluating the potential for implementing similar 
programs in the Hawaiian Islands ASW operations areas. In addition, a 
Statement of Interest has been promulgated to initiate a similar 
research and monitoring project in the Hawaiian Islands and the 
remainder of the Pacific Fleet OPAREAs. The execution of funding to 
begin the resultant monitoring is planned for the fall of 2006.

Reporting

    The RIMPAC Operational Order Environmental Annex (see example in 
Appendix A of the application) includes specific reporting requirements 
related to marine mammals.

Additional Proposed Mitigation, Monitoring, and Reporting Measures 
Required by NMFS

    The following protective mitigation and monitoring measures will be 
implemented in addition to the standard operating procedures discussed 
in the previous section:
    (1) The Navy will operate sonar at the lowest practicable level, 
not to exceed 235 dB, except for occasional short periods of time to 
meet tactical training objectives.
    (2) Safety Zones - When marine mammals are detected by any means 
(aircraft, lookout, or acoustically) within 1000 m (3280 ft) of the 
sonar dome (the bow), the ship or submarine will limit active 
transmission levels to at least 6 dB below normal operating levels. 
Ships and submarines will continue to limit maximum ping levels by this 
6-dB factor until the animal has been seen to leave the area, has not 
been seen for 30 minutes, or the vessel has transited more than 2000 m 
beyond the location of the sighting.
    Should a marine mammal be detected within or closing to inside 500 
m (1640 ft) of the sonar dome, active sonar transmissions will be 
limited to at least 10 dB below the equipment's normal operating level. 
Ships and submarines will continue to limit maximum ping levels by this 
10-dB factor until the animal has been seen to leave the area, has not 
been seen for 30 minutes, or the vessel has transited more than 1500 m 
(4920 ft) beyond the location of the sighting.
    Should the marine mammal be detected within or closing to inside 
200 m (656 ft) of the sonar dome, active sonar transmissions will 
cease. Sonar will not resume until the animal has been seen to leave 
the area, has not been seen for 30 minutes, or the vessel has transited 
more than 1200 m beyond the location of the sighting.
    If the Navy is operating sonar above 235 dB and any of the 
conditions necessitating a powerdown arise ((f), (g), or (h)), the Navy 
shall follow the requirements as though they were operating at 235 dB - 
the normal operating level (i.e., the first powerdown will be to 229 
dB, regardless of at what level above 235 sonar was being operated).
    (3) In strong surface ducting conditions, the Navy will enlarge the 
safety zones such that a 6-dB power-down will occur if a marine mammal 
enters the zone within a 2000 m (6561 ft) radius around the source, a 
10-dB power-down will occur if an animal enters the 1000 m (3280 ft) 
zone, and shut down will occur when an animal closes within 500 m (1640 
ft) of the sound source.
    (4) In low visibility conditions (i.e., whenever the entire safety 
zone cannot be effectively monitored due to nighttime, high sea state, 
or other factors), the Navy will use additional detection measures, 
such as infrared (IR) or enhanced passive acoustic detection. If 
detection of marine mammals is not possible out to the prescribed 
safety zone, the Navy will power down sonar (per the safety zone 
criteria above) as if marine mammals are present immediately beyond the 
extent of detection. (For example, if detection of marine mammals is 
only possible out to 700 m (2296 ft), the Navy must implement a 6-dB 
powerdown, as though an animal is present at 701 m (2299 ft), which is 
inside the 1000-m (3280-ft) safety zone)
    (5) With the exception of three specific choke-point exercises 
(special

[[Page 38732]]

measures outlined in item 8), the Navy will not conduct sonar 
activities in constricted channels or canyon-like areas.
    (6) With the exception of three specific ``choke-point'' exercises 
(special measures outlined in item 8), and events occurring on range 
areas managed by PMRF, the Navy will not operate mid-frequency sonar 
within 25 km (13.5 nm) of the 200 m (656 ft) isobath.
    (7) Navy watchstanders, the individuals responsible for detecting 
marine mammals in the Navy's standard operating procedures, will 
participate in marine mammal observer training by a NMFS-approved 
instructor (NMFS will work with Navy to develop appropriate format, 
potentially to be presented to Navy personnel during the port phase of 
RIMPAC, June 26-30). Training will focus on identification cues and 
behaviors that will assist in the detection of marine mammals and the 
recognition of behaviors potentially indicative of injury or stranding. 
Training will also include information aiding in the avoidance of 
marine mammals and the safe navigation of the vessel, as well as 
species identification review (with a focus on beaked whales and other 
species likely to strand). At least one individual who has received 
this training will be present, and on watch, at all times during 
operation of tactical mid-frequency sonar, on each vessel operating 
mid-frequency sonar.
    (8) The Navy will conduct no more than three ``choke-point'' 
exercises. These exercises will occur in the Kaulakahi Channel (between 
Kauai and Niihau) and the Alenuihaha Channel (between Maui and Hawaii). 
These exercises fall outside of the requirements listed above in 5 and 
6, i.e., to avoid canyon-like areas and to operate sonar farther than 
25 km (13.5 nm) from the 200 m (656 ft) isobath. The additional 
measures required for these three choke-point exercises are as follows:
    (a) The Navy will provide NMFS (Stranding Coordinator and Protected 
Resources, Headquarters) and the Hawaii marine patrol with information 
regarding the time and place for the choke-point exercises 24 hours in 
advance of the exercises.
    (b) The Navy will have at least one dedicated Navy marine mammal 
observer who has received the NMFS-approved training mentioned above in 
7, on board each ship and conducting observations during the operation 
of mid-frequency tactical sonar during the choke-point exercises. The 
Navy has also authorized the presence of two experienced marine mammal 
observers (non-Navy personnel) to embark on Navy ships for observation 
during the exercise.
    (c) Prior to start up or restart of sonar, the Navy will ensure 
that a 2000-m (6561-ft) radius around the sound source is clear of 
marine mammals.
    (d) The Navy will coordinate a focused monitoring effort around the 
choke-point exercises, to include pre-exercise monitoring (2 hours), 
during-exercise monitoring, and post-exercise monitoring (1-2 days). 
This monitoring effort will include at least one dedicated aircraft or 
one dedicated vessel for realtime monitoring from the pre- through 
post-monitoring time period, except at night. The vessel or airplane 
may be operated by either dedicated Navy personnel, or non-Navy 
scientists contracted by the Navy, who will be in regular communication 
with a Tactical Officer with the authority to shut-down, power-down, or 
delay the start-up of sonar operations. These monitors will communicate 
with this Officer to ensure the 2000-m (6561-ft) safety zone is clear 
prior to sonar start-up, to recommend power-down and shut-down during 
the exercise, and to extensively search for potentially injured or 
stranding animals in the area and down-current of the area post-
exercise.
    (e) The Navy will further contract an experienced cetacean 
researcher to conduct systematic aerial reconnaissance surveys and 
observations before, during, and after the choke-point exercises with 
the intent of closely examining local populations of marine mammals 
during the RIMPAC exercise.
    (f) Along the Kaulakahi Channel (between Kauai and Niihau), 
shoreline reconnaissance and nearshore observations will be undertaken 
by a team of observers located at Kekaha (the approximate mid point of 
the Channel). Additional observations will be made on a daily basis by 
range vessels while enroute from Port Allen to the range at PMRF (a 
distance of approximately 16 nm (30 km) and upon their return at the 
end of each day's activities. Finally, surveillance of the beach 
shoreline and nearshore waters bounding PMRF will occur randomly around 
the clock a minimum four times in each 24 hour period.
    (g) In the Alenuihaha Channel (between Maui and Hawaii), the Navy 
will conduct shoreline reconnaissance and nearshore observations by a 
team of observers rotating between Mahukona and Lapakahi before, 
during, and after the exercise.
    (9) The Navy will conduct five exercises in the Pacific Missile 
Range Facilities that fall within 25 km (13.5 nm) of the 200-m (656-ft) 
isobath. The live sonar component of these 5 exercises will total 
approximately 6.5 hours. During these exercises, the Navy will conduct 
the monitoring described in (8)(b), (c), and (d).
    (10) NMFS and the Navy will continue coordination on the 
``Communications and Response Protocol for Stranded Marine Mammal 
Events During Navy Operations in the Pacific Islands Region'' that is 
currently under preparation by NMFS PIRO to facilitate communication 
during RIMPAC. The Navy will coordinate with the NMFS Stranding 
Coordinator for any unusual marine mammal behavior, including 
stranding, beached live or dead cetacean(s), floating marine mammals, 
or out-of-habitat/milling live cetaceans that may occur at any time 
during or shortly after RIMPAC activities. After RIMPAC, NMFS and the 
Navy (CPF) will prepare a coordinated report on the practicality and 
effectiveness of the protocol that will be provided to Navy/NMFS 
leadership.
    (11)The Navy will provide a report to NMFS after the completion of 
RIMPAC that includes:
    (a) An estimate of the number of marine mammals affected by the 
RIMPAC ASW exercises and a discussion of the nature of the effects, if 
observed, based on both modeled results of real-time exercises and 
sightings of marine mammals.
    (b) An assessment of the effectiveness of the mitigation and 
monitoring measures with recommendations of how to improve them.
    (c) Results of all of the marine species monitoring (real-time Navy 
monitoring from all platforms, independent aerial monitoring, shore-
based monitoring at chokepoints, etc.) before, during, and after the 
RIMPAC exercises.
    (d) As much information (unclassified and, to appropriate 
recipients, classified ``secret'') as the Navy can provide including, 
but not limited to, where and when sonar was used (including sources 
not considered in take estimates, such as submarine and aircraft 
sonars) in relation to any measured received levels (such as at 
sonobuoys or on PMRF range), source levels, numbers of sources, and 
frequencies, so it can be coordinated with observed cetacean behaviors.
    The mitigation and monitoring proposed in this IHA are intended to 
function adaptively, and NMFS fully expects to refine them for future 
authorizations based on the reporting input from the Navy.

[[Page 38733]]

Shutdown Criteria

    Pursuant to section101(a)(5)(D)(iv) of the MMPA, The Secretary of 
Commerce shall modify, suspend, or revoke an authorization if the 
Secretary finds that the provisions of clauses (i) or (ii) of section 
101(a)(5)(D) are not being met. Marine mammal strandings are a common 
event in Hawaii and over the course of the 22 days of ASW exercises, 
NMFS expects that 1 or 2 single-animal strandings may occur that are 
not related to RIMPAC. To distinguish these strandings from a stranding 
that NMFS believes may occur as a result of exposure to the hull-
mounted Mid-Frequency Active Sonar (MFAS) activities covered in this 
authorization, NMFS and the U.S. Navy have established this ``shutdown 
criteria'' to provide the necessary time for the Secretary to 
investigate the cause of uncommon marine mammal stranding events and 
determine whether the IHA should be modified, suspended, or revoked. 
The established protocols in place between NMFS Stranding Coordinator 
Pacific and COMPACFLT Environmental Coordinator are the basis for this 
document.

Definitions

    Shutdown area-An area within 50 km (27 nm) of the half of the 
island centered on the place where the animal was found.
    Limited Chokepoint Shutdown-Temporary suspension of the hull-
mounted MFAS during the choke point exercises.
    Uncommon Stranding Event-An event involving any one of the 
following:
     Two or more individuals of a commonly stranded species 
found dead or live beached within a two day period (not including 
mother/calf pairs), or
     A single uncommonly stranded whale found dead or live 
beached, or
     A group of 10 or more animals milling out of habitat (e.g. 
such as occurred with melon headed whales in Hanalei Bay in 2004)
    Commonly Stranded Odontocete Species-spinner dolphin, striped 
dolphin, Kogia sp, Tursiops sp, melon-headed whale, pilot whale, and 
sperm whales.
    Investigation-consists of the following components and can be 
conducted within 3 days of notification of a stranding event
    (1) NMFS will undertake a survey around stranding site to search 
for other stranded/out of habitat animals
    (2) Physical Exam of animal (and blood work if live animals) to 
investigate and verify presence or absences
    (a) Of impacts on the hearing of live stranded mammals. If feasible 
and if medical condition of the animal allows, Acoustic Brainstem 
Response (ABR) and Auditory Evoke Potential (AEP) will be conducted to 
rapidly assess whether the hearing of a live stranded animal has been 
affected.
    (b) Of long term illness (based on body condition), life 
threatening infection, blunt force traumas or fishery interaction that 
would indicate the likely cause of death
    (c) Of gross lesions or CT/MRI findings that have been documented 
in previous sonar related strandings (i.e., gas emboli or fat emboli, 
hemorrhages in organs, hemorrhage in ears). Note: Care must be taken to 
control and document the conditions under which the carcass is handled. 
The investigation of microscopic histology can be compromised by the 
decomposition, freeze/thaw, transport conditions and subsequent 
necropsy of the mammal.
    (3) Evaluation of environmental conditions (through remote sensing, 
modeling and direct observations) preceding and during the stranding or 
out of habitat event to determine if environmental factors that are 
known to contribute to such events were in place, such as fronts, 
swells, particular currents, Kona winds, prey abundance, seismic 
events, lunar phase, toxins or predators in area. Navy will assist in 
providing environmental data that is otherwise collected for tactical 
purposes.
     Strong evidence of environmental factors that might 
contribute to stranding event were present
     Weak to no evidence of environmental factors that might 
contribute to stranding were present
    (4) Within 72 hours of notification of an Uncommon Stranding Event, 
Navy will provide information regarding where and what (or where not) 
the Navy was operating sonar leading up to the stranding.

Shutdown Protocol:

    1. NMFS will respond to all reports of marine mammal strandings 
during the exercise. If a stranding is suspected to be an Uncommon 
Stranding Event, the NMFS Stranding Coordinator Pacific will 
immediately notify the COMPACFLT Environmental Coordinator. The 
Coordinators will utilize existing protocols as amplified by this 
document to verify whether or not an event constitutes an Uncommon 
Stranding Event.
    2. If an Uncommon Stranding Event is verified, NMFS will inform the 
Navy and will identify the shutdown area. NMFS will also confirm with 
Navy the start time and duration of any recent choke-point exercises.
    3. The Navy will cease hull-mounted MFAS activities in the shutdown 
area. Additionally, if the uncommon stranding event occurred during or 
within 48 hours of the end of a choke point exercise the Navy will 
invoke the limited choke point shutdown for up to 4 days.
    4. NMFS will conduct its investigation and inform the Navy of its 
findings as soon as possible, but no later than 4 days from the date 
the Uncommon Stranding Event was verified.
    5. If the results of the investigation indicate that the stranding 
resulted from causes other than activities covered by this 
authorization NMFS will inform the Navy that exercises authorized by 
this IHA may resume.
    6. If NMFS determines that the Navy's activities authorized under 
the IHA may have contributed to the uncommon marine mammal stranding 
event NMFS will advise the Navy whether the IHA should be modified, 
suspended, or revoked.

Communication

    Effective communication is critical to the successful 
implementation of this protocol.
     NMFS will provide Navy with a list of NMFS staff, 
empowered to inform the Navy to implement the appropriate shutdown 
protocol as described above. These individuals will be reachable 24 
hours/day for 22 consecutive days (a pre-identified group will be on 
call in shifts to make these decisions and a phone tree will be 
available). Week-end on call will be designated for HQ staff by noon on 
Friday.
     Navy will provide NMFS a list of people empowered to 
implement the shut down protocol, at least one of whom will be 
reachable at any hour during the 22 days of ASW exercises prior to the 
initiation of the exercise

Negligible Impact Determination and Avoidance of Mortality of Marine 
Mammals

Negligible Impact

    Negligible impact is defined as ''...an impact resulting from the 
specified activity that cannot be reasonably expected to, and is not 
reasonably likely to, adversely affect the species or stock through 
effects on annual rates of recruitment or survival.'' Because NMFS does 
not authorize or expect any mortality or injury to result from these 
activities, NMFS believes the authorized takings, by harassment, can be 
reasonably expected not to adversely

[[Page 38734]]

affect the species or stock through effects on annual rates of 
survival. NMFS acknowledges that Level B Harassment to large enough 
portions of a species or stock or over a long enough time could 
potentially adversely affect survival rates, however, due to the 
required mitigation and monitoring during this proposed activity (which 
reduce the numbers of animals exposed and the levels they are exposed 
to), as well as the duration and nature of the activities, NMFS does 
not believe the RIMPAC ASW exercises will adversely affect survival of 
any of the affected species.
    As discussed earlier (see Stress Responses), some portion of the 
animals exposed to SELs greater than 173 dB during the RIMPAC exercises 
will undergo a physiological stress response. Relationships between 
stress responses and inhibition of reproduction (by suppression of pre-
ovulatory luteinizing hormones, for example) have been well-documented. 
However, NMFS believes the manner in which individual animals respond 
to different stressors varies across a continuum that is normally 
distributed with hyper-sensitive and hypo-sensitive animals being on 
the tails of the curve. Therefore, NMFS does not believe that much more 
than a small portion of animals exposed to sound levels above 173 dB 
would respond in a manner that physiologically inhibits reproduction. 
Additionally, suppression of pre-ovulatory luteinizing hormones would 
only be of a concern to species whose period of reproductive activity 
overlaps in time and space with RIMPAC. NMFS also believes that due to 
the enhanced nature of the monitoring required in this authorization, 
combined with the shutdown zones, the likelihood of seeing and avoiding 
mother/calf pairs or animals engaged in social reproductive behaviors 
is high. Consequently, NMFS believes it is unlikely the authorized 
takings will adversely affect the species or stocks through effects on 
annual rates of recruitment.
    Table 3 summarizes the reasoning behind NMFS' negligible impact 
determination, in terms of how mitigation measures contribute towards 
it and what other factors were considered. Several of the measures 
addressed have a visual monitoring component, which NMFS recognizes is 
most effective in reducing impacts to larger animals and species that 
travel in larger groups. However, NMFS has also included coastal and 
steep bathymetry restrictions, and extended power-down/shut-down zones, 
which will significantly reduce the numbers of animals taken, 
regardless of whether they are cryptic or easily seen, and will 
effectively reduce the likelihood of mortality, or serious injury, of 
marine mammals.
BILLING CODE 3510-22-S

[[Page 38735]]

[GRAPHIC] [TIFF OMITTED] TN07JY06.001

BILLING CODE 3510-22-C
    As mentioned in Table 3, the number of individuals estimated to be 
harassed, in relation to the abundance of the species or stock, factors 
into the

[[Page 38736]]

negligible impact determination. In Table 4, NMFS shows the raw percent 
of the Navy's modeled exposures for each species divided by the 
estimated abundance of each species within the Hawaiian EEZ. Though 
NMFS uses these numbers as a starting point for assessing approximately 
what portion of any affected population may be affected by Level B 
Harassment through this activity, these numbers suggest impacts to a 
far greater portion of the populations than NMFS believes will actually 
occur because they do not take into account several important factors 
discussed below. Though no particular numeric reduction of the raw 
modeled percentages can be justified, they are semi-quantitatively 
addressed in Table 4, which illustrates how certain factors and 
protective measures reduce the percent of population affected by these 
activities for each species. Below are the reasons NMFS believes that 
the percentages of each stock affected are lower:
    (1) The effectiveness of mitigation measures has not been taken 
into account. The following measures will reduce the numbers of 
individuals harassed:
    (a) The 25 km (13.5 nm) coastal exclusion area - For species that 
have significantly higher densities inshore (10 - 40 times greater 
within 25 nm (46 km) of the shore), the Navy is excluded from operating 
sonar within 25 km (13.5 nm) of shore, which significantly reduces the 
numbers of individuals exposed to sonar. This an especially important 
point for the spinner dolphin, which has an inshore density of 40 times 
that of the offshore density.
    (b) Monitoring and implementation of powerdowns, shutdowns, and 
avoidance maneuvers - Species of large body size and large average 
group size are significantly more likely to be detected by monitoring 
(active submarine sonar prior to startup, and visual monitoring during 
the exercise) than those animals that are deep divers or cryptic and 
the surface, and, therefore, powerdowns and shutdowns are expected to 
be especially effective in reducing the numbers of these species 
affected.
    (2) The estimated percentage of the portion of the population or 
stock harassed was calculated by dividing the modeled Level B 
harassment takes by the estimated abundance in the Hawaiian EEZ. NMFS 
beleives that the modeled number of takes is an overestimate of the 
actual number for the following reasons:
    (a) As discussed in more detail in the sub-section entitled 
``Model'' in the ``Estimated Number of Takes'' section previously, NMFS 
believes that the model overestimates the take of marine mammals 
significantly by assuming that animals remain stationary throughout 
their overlap with the ensonified area and by assuming that an animal 
is always located in the loudest point in any column of ensonified 
water.
    (b) Additionally, when further analyzing the effects of these takes 
on the affected species and stocks, NMFS believes it would be 
unrealistic, considering the fast-paced, multi-vessel nature of the 
exercise and the fact that the exercise continues over the course of a 
month in an area with resident populations of cetaceans, to assume that 
each exposure involves a different whale. Some whales are likely to be 
exposed once, while others are likely to be exposed more than once. One 
way to numerically address this concept is to assume that the exposure 
events would be distributed normally, with the exposures that each 
affect a different whale falling within one standard deviation (68.26 
percent), the exposures assumed to affect different whales each twice 
within 2 standard deviations (27.18 percent), the exposures assumed to 
affect different whales each 3 times within 3 standard deviations (4.28 
percent), and so on, if the populations are larger. If this 
relationship is applied to estimated numbers of exposures produced by 
the Navy's model, the calculated number of affected animals is 
approximately 16 percent less than the estimated number of exposures 
for any given species. NMFS acknowledges the lack of specific sonar/
marine mammal data to support this approach, however, NMFS believes 
that this approach will help us more closely approximate the number of 
animals potentially taken than an assumption that each sonar ping 
affects a different cetacean.
    (3) As mentioned in number 2, the estimated percentage of the 
portion of the population or stock harassed was calculated by dividing 
the modeled Level B harassment takes by the estimated abundance in the 
Hawaiian EEZ. However, almost all of the biological populations extend 
past the boundary of the Hawaiian EEZ, some to an unknown distance, 
some pantropically, some to the northern Pacific, and some farther. 
This means that the percentages of populations effected are further 
lower than the percentages reported in Table. This point may be less 
applicable to spinner dolphins and bottlenose dolphins as there may be 
additional population sub-division within the Hawaiian Islands.
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[GRAPHIC] [TIFF OMITTED] TN07JY06.002

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    Subsequent to the proposed IHA being published in the Federal 
Register, NMFS published the Final Report addressing the melon-headed 
whale

[[Page 38738]]

event that occurred in Hanalei Bay during the RIMPAC exercises last 
year. This report concluded that mid-frequency sonar operation in the 
area was a plausible, if not likely, contributor to the event. NMFS 
recognizes that the deaths of these animals could potentially have 
resulted measurable effects on the population. To minimize that 
possibility in the future, NMFS will implement Shutdown Critieria 
during RIMPAC that require the Navy to cease sonar operations if an 
uncommon stranding event (such as the Hanalei event) is verified (see 
Mitigation, Monitoring, and Reporting above).
    NMFS has determined that, based on the nature and duration of the 
proposed activities, and dependent upon the full implementation of the 
required mitigation and monitoring measures, which will reduce both the 
severity of effects on animals that may be potentially exposed and the 
numbers of animals potentially exposed, the RIMPAC ASW exercises will 
result in the Level B Harassment of the species addressed here, 
consisting primarily of temporary behavioral modifications, in the form 
of temporary displacement from feeding or sheltering areas, low-level 
physiological stress responses, and, to a lesser extent, TTS. NMFS has 
further determined that these takings, by harassment, will result in a 
negligible impact to the affected species or stocks.

Avoidance of Serious Injury or Mortality

    NMFS has required a suite of mitigation measures in the IHA that 
reduces the likelihood of a stranding resulting from the RIMPAC ASW 
activities. However, several points that were emphasized in the public 
comments (i.e., the difficulty (even in ideal conditions) of detecting 
beaked whales, which have been among the species stranded in most of 
the strandings associated with sonar, and the fact that choke-point 
exercises will be conducted both at night and in surface-ducting 
conditions) and the published conclusions of the melon-headed whale 
stranding report do not allow NMFS to rule out the possibility of a 
stranding resulting from the RIMPAC ASW activities. Consequently, NMFS 
has included specific shutdown criteria (see Mitigation and Monitoring, 
above), which are intended to ensure MMPA compliance. These criteria 
require the Navy to temporarily cease operating sonar in a designated 
area when a stranding is verified during the RIMPAC ASW exercise. NMFS 
will then conduct an investigation, and if NMFS finds that the Navy's 
activities may have contributed to the stranding, NMFS will modify, 
revoke, or suspend the IHA.

Endangered Species Act (ESA)

    There are seven marine mammal species and five sea turtle species 
that are listed as endangered or threatened under the ESA with 
confirmed or possible occurrence in the RIMPAC ASW area: humpback 
whale, North Pacific right whale, sei whale, fin whale, blue whale, 
sperm whale, and Hawaiian monk seal, loggerhead sea turtle, the green 
sea turtle, hawksbill sea turtle, leatherback sea turtle, and olive 
ridley sea turtle.
    Under section 7 of the ESA, the Navy consulted with NMFS on the 
proposed RIMPAC ASW exercises. NMFS also consulted internally on the 
issuance of an IHA under section 101(a)(5)(D) of the MMPA for this 
activity. The Endangered Species Division, NMFS, issued a Biological 
Opinion (BiOp) that concluded that the proposed action is not likely to 
result in jeopardy to the species or in the destruction or adverse 
modification of critical habitat..
    The BiOp includes an incidental take statement for harassment of 
sperm whales, fin whales, and sei whales, which also contains the same 
required terms and conditions (mitigation, monitoring, and reporting) 
as those contained in the IHA.

National Environmental Policy Act (NEPA)

    In April, 2006, the Navy prepared a revised 2006 Supplement on the 
2002 Programmatic Environmental Assessment (EA) on RIMPAC. NMFS has 
adopted the Navy's EA and issued an associated Finding of No 
Significant Impact (FONSI).

Conclusions

    A determination of negligible impact is required for NMFS to 
authorize incidental take of marine mammals. By regulation, an activity 
has a ``negligible impact'' on a species or stock when it is determined 
that the total taking is not likely to reduce annual rates of adult 
survival or recruitment (i.e., offspring survival, birth rates). Based 
on each species' life history information, the expected behavioral 
patterns of the animals in the RIMPAC locations, the duration of the 
activity, the anticipated implementation of the required mitigation and 
monitoring measures, and an analysis of the behavioral disturbance 
levels in comparison to the overall populations, an analysis of the 
potential impacts of the Proposed Action on species recruitment or 
survival support the conclusion that proposed RIMPAC ASW training 
events would have a negligible impact on the affected species or 
stocks. NMFS has also determined that the issuance of the IHA would not 
have an unmitigable adverse impact on the availability of the affected 
species or stocks for subsistence use. Additionally, NMFS has set forth 
in its IHA the permissible methods of taking and requirements 
pertaining to the mitigation, monitoring and reporting of such takings.

Authorization

    NMFS has issued an IHA to the Navy for conducting ASW exercises, 
using tactical mid-frequency sonar, in the Hawaiian Islands OpArea, 
provided the previously mentioned mitigation, monitoring, and reporting 
requirements are incorporated.

    Dated: June 29, 2006.
James H. Lecky,
Director, Office of Protected Resources, National Marine Fisheries 
Service.
[FR Doc. 06-6050 Filed 7-6-06; 8:45 am]
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