Takes of Marine Mammals Incidental to Specified Activities; Navy Research, Development, Test and Evaluation Activities at the Naval Surface Warfare Center Panama City Division, 49412-49425 [2012-20167]

Agencies

• DEPARTMENT OF COMMERCE
• National Oceanic and Atmospheric Administration

[Federal Register Volume 77, Number 159 (Thursday, August 16, 2012)]
[Notices]
[Pages 49412-49425]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2012-20167]



[[Page 49412]]

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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

RIN 0648-XA950


Takes of Marine Mammals Incidental to Specified Activities; Navy 
Research, Development, Test and Evaluation Activities at the Naval 
Surface Warfare Center Panama City Division

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

ACTION: Notice of issuance of an incidental harassment authorization.

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SUMMARY: In accordance with provisions of the Marine Mammal Protection 
Act (MMPA) as amended, notification is hereby given that an Incidental 
Harassment Authorization (IHA) has been issued to the U.S. Navy (Navy) 
to take marine mammals, by harassment, incidental to conducting 
research, development, test and evaluation (RDT&E) activities at the 
Naval Surface Warfare Center Panama City Division (NSWC PCD).

DATES: This authorization is effective from July 27, 2012, until July 
26, 2013.

ADDRESSES: A copy of the application, IHA, and/or a list of references 
used in this document may be obtained by writing to P. Michael Payne, 
Chief, Permits and Conservation Division, Office of Protected 
Resources, National Marine Fisheries Service, 1315 East-West Highway, 
Silver Spring, MD 20910-3225.

FOR FURTHER INFORMATION CONTACT: Shane Guan, NMFS, (301) 427-8401.

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 (Secretary) to allow, upon request, 
the incidental, but not intentional taking of small numbers of marine 
mammals by U.S. citizens who engage in a specified activity (other than 
commercial fishing) if certain findings are made and regulations are 
issued or, if the taking is limited to harassment, notice of a proposed 
authorization is provided to the public for review.
    Authorization for incidental takings 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 (where 
relevant), and if the permissible methods of taking and requirements 
pertaining to the mitigation, monitoring and reporting of such taking 
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.''
    The National Defense Authorization Act of 2004 (NDAA) (Pub. L. 108-
136) removed the ``small numbers'' and ``specified geographical 
region'' limitations and amended the definition of ``harassment'' as it 
applies to a ``military readiness activity'' to read as follows 
(Section 3(18)(B) of the MMPA):
    (i) Any act that injures or has the significant potential to injure 
a marine mammal or marine mammal stock in the wild [Level A 
Harassment]; or
    (ii) any act that disturbs or is likely to disturb a marine mammal 
or marine mammal stock in the wild by causing disruption of natural 
behavioral patterns, including, but not limited to, migration, 
surfacing, nursing, breeding, feeding, or sheltering, to a point where 
such behavioral patterns are abandoned or significantly altered [Level 
B Harassment].
    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. 
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 the authorization.

Summary of Request

    NMFS received an application on December 28, 2011, from the Navy 
for the taking, by harassment, of marine mammals incidental to 
conducting testing of the AN/AQS-20A Mine Reconnaissance Sonar System 
(hereafter referred to as the Q-20) in the Naval Surface Warfare 
Center, Panama City Division (NSWC PCD) testing range in the Gulf of 
Mexico (GOM) from April 2012 through April 2013. The Q-20 sonar test 
activities are proposed to be conducted in the non-territorial waters 
of the United States (beyond 12 nautical miles) in the Gulf of Mexico 
(GOM, see Figure 2-1 of the Navy IHA application).

Description of the Specific Activity

    The purpose of the Navy's activities is to meet the developmental 
testing requirements of the Q-20 system by verifying its performance in 
a realistic ocean and threat environment and supporting its integration 
with the Remote Multi-Mission Vehicle (RMMV) and ultimately the 
Littoral Combat Ship (LCS). Testing would include component, subsystem-
level, and full-scale system testing in an operational environment.
    The need for the proposed activities is to support the timely 
deployment of the Q-20 to the operational Navy for Mine Countermeasure 
(MCM) activities abroad, allowing the Navy to meet its statutory 
mission to deploy naval forces equipped and trained to meet existing 
and emergent threats worldwide and to enhance its ability to operate 
jointly with other components of the armed forces.
    The proposed activities are to test the Q-20 from the RMMV and from 
surrogate platforms such as a small surface vessel or helicopter. The 
RMMV or surrogate platforms will be deployed from the Navy's new LCS or 
its surrogates. The Navy is evaluating potential environmental effects 
associated with the Q-20 test activities proposed for the Q-20 Study 
Area (see below for detailed description of the Study Area), which 
includes non-territorial waters of Military Warning Area 151 (W-151; 
includes Panama City Operating Area). Q-20 test activities occur at sea 
in the waters present within the Q-20 Study Area. No hazardous waste is 
generated at sea during Q-20 test activities.
    A detailed description of the NSWC PCD's Q-20 test activities is 
provided in the Federal Register for the proposed IHA (77 FR 12010; 
February 28, 2012), and there was no change in the proposed action from 
the proposed IHA. Therefore, it is not repeated here.

Comments and Responses

    A notice of receipt and request for public comment on the 
application and proposed authorization was published on February 28, 
2012 (77 FR 12010). During the 30-day public comment period, the Marine 
Mammal Commission (Commission) and a private citizen provided comments.
    Comment 1: The Commission recommends that NMFS issue the IHA, but 
condition it to require the Navy to conduct its monitoring for at least 
15 minutes prior to the initiation of and for at least 15 minutes after 
the cessation of Q-20 testing activities.
    Response: NMFS agrees with the Commission's recommendations and

[[Page 49413]]

worked with the Navy to incorporate the said condition to require the 
Navy to conduct its monitoring for at least 15 minutes prior to the 
initiation of and for at least 15 minutes after the cessation of Q-20 
testing activities.
    Comment 2: One private citizen wrote against NMFS issuing the IHA 
to the Navy due to concerns about ``severe injuries and killings to 
thousands of marine mammals.''
    Response: NMFS does not agree with the commenter. As discussed in 
detail in the Federal Register notice for the proposed IHA (77 FR 
12010; February 28, 2012) and in sections below, the Navy's Q-20 
testing activity would only affect a small number of marine mammals by 
Level B behavioral harassment. No injury or mortality to marine mammals 
is expected to occur, nor will be authorized.

Description of Marine Mammals in the Area of the Specified Activity

    There are 29 marine mammal species under NMFS' jurisdiction that 
may occur in the Q-20 Study Area (Table 1). These include 7 mysticetes 
(baleen whales) and 22 odontocetes (toothed whales). Table 1 also 
includes the Federal status of these marine mammal species. Six of 
these marine mammal species under NMFS' jurisdiction are also listed as 
federally endangered under the Endangered Species Act (ESA) and could 
potentially occur in the Study Area: the humpback whale, North Atlantic 
right whale, sei whale, fin whale, blue whale, and sperm whale. Of 
these 29 species with occurrence records in the Q-20 Study Area, 22 
species regularly occur there. These 22 species are: Bryde's whale, 
sperm whale, pygmy sperm whale, dwarf sperm whale, Cuvier's beaked 
whale, Gervais' beaked whale, Sowerby's beaked whale, Blainville's 
beaked whale, killer whale, false killer whale, pygmy killer whale, 
short-finned pilot whale, Risso's dolphin, melon-headed whale, rough-
toothed dolphin, bottlenose dolphin, Atlantic spotted dolphin, 
pantropical spotted dolphin, striped dolphin, spinner dolphin, Clymene 
dolphin, and Fraser's dolphin. The remaining 7 species (i.e., North 
Atlantic right whale, humpback whale, sei whale, fin whale, blue whale, 
minke whale, and True's beaked whale) are extralimital and are excluded 
from further consideration of impacts from the NSWC PCD Q-20 testing 
analysis.

 Table 1--Marine Mammal Species Potentially Found in the Q-20 Study Area
------------------------------------------------------------------------
  Family and scientific name       Common name         Federal status
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                              Order Cetacea
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                   Suborder Mysticeti (baleen whales)
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Eubalaena glacialis...........  North Atlantic     Endangered.
                                 right whale.
Megaptera novaeangliae........  Humpback whale...  Endangered.
Balaenoptera acutorostrata....  Minke whale......
B. brydei.....................  Bryde's whale....
B. borealis...................  Sei whale........  Endangered.
B. physalus...................  Fin whale........  Endangered.
B. musculus...................  Blue whale.......  Endangered.
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                  Suborder Odontoceti (toothed whales)
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Physeter macrocephalus........  Sperm whale......  Endangered.
Kogia breviceps...............  Pygmy sperm whale
K. sima.......................  Dwarf sperm whale
Ziphius cavirostris...........  Cuvier's beaked
                                 whale.
Mesoplodon europaeus..........  Gervais' beaked
                                 whale.
M. Mirus......................  True's beaked
                                 whale.
M. bidens.....................  Sowerby's beaked
                                 whale.
M. densirostris...............  Blainville's
                                 beaked whale.
Steno bredanensis.............  Rough-toothed
                                 dolphin.
Tursiops truncatus............  Bottlenose
                                 dolphin.
Stenella attenuata............  Pantropical
                                 spotted dolphin.
S. frontalis..................  Atlantic spotted
                                 dolphin.
S. longirostris...............  Spinner dolphin..
S. clymene....................  Clymene dolphin..
S. coeruleoalba...............  Striped dolphin..
Lagenodephis hosei............  Fraser's dolphin.
Grampus griseus...............  Risso's dolphin..
Peponocephala electra.........  Melon-headed
                                 whale.
Feresa attenuata..............  Pygmy killer
                                 whale.
Pseudorca crassidens..........  False killer
                                 whale.
Orcinus orca..................  Killer whale.....
Globicephala macrorhynchus....  Short-finned
                                 pilot whale.
------------------------------------------------------------------------

    The Navy's IHA application contains information on the status, 
distribution, seasonal distribution, and abundance of each of the 
species under NMFS jurisdiction mentioned in this document. Please 
refer to the application for that information (see ADDRESSES). 
Additional information can also be found in the NMFS Stock Assessment 
Reports (SAR). The Atlantic 2011 SAR is available at: https://www.nmfs.noaa.gov/pr/pdfs/sars/ao2011.pdf.

A Brief Background on Sound

    An understanding of the basic properties of underwater sound is 
necessary to comprehend many of the concepts and analyses presented in 
this document. A summary is included below.

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    Sound is a wave of pressure variations propagating through a medium 
(for the sonar considered in this IHA, the medium is marine water). 
Pressure variations are created by compressing and relaxing the medium. 
Sound measurements can be expressed in two forms: intensity and 
pressure. Acoustic intensity is the average rate of energy transmitted 
through a unit area in a specified direction and is expressed in watts 
per square meter (W/m\2\). Acoustic intensity is rarely measured 
directly, it is derived from ratios of pressures; the standard 
reference pressure for underwater sound is 1 [micro]Pa; for airborne 
sound, the standard reference pressure is 20 [micro]Pa (Urick, 1983).
    Acousticians have adopted a logarithmic scale for sound 
intensities, which is denoted in decibels (dB). Decibel measurements 
represent the ratio between a measured pressure value and a reference 
pressure value (in this case 1 [micro]Pa or, for airborne sound, 20 
[micro]Pa). The logarithmic nature of the scale means that each 10 dB 
increase is a tenfold increase in power (e.g., 20 dB is a 100-fold 
increase, 30 dB is a 1,000-fold increase). Humans perceive a 10-dB 
increase in noise as a doubling of sound level, or a 10 dB decrease in 
noise as a halving of sound level. The term ``sound pressure level'' 
implies a decibel measure and a reference pressure that is used as the 
denominator of the ratio. Throughout this document, NMFS uses 1 
[micro]Pa as a standard reference pressure unless noted otherwise.
    It is important to note that decibels underwater and decibels in 
air are not the same and cannot be directly compared. To estimate a 
comparison between sound in air and underwater, because of the 
different densities of air and water and the different decibel 
standards (i.e., reference pressures) in water and air, a sound with 
the same intensity (i.e., power) in air and in water would be 
approximately 63 dB lower in air. Thus, a sound that is 160 dB loud 
underwater would have the same approximate effective intensity as a 
sound that is 97 dB loud in air.
    Sound frequency is measured in cycles per second, or Hertz 
(abbreviated Hz), and is analogous to musical pitch; high-pitched 
sounds contain high frequencies and low-pitched sounds contain low 
frequencies. Natural sounds in the ocean span a huge range of 
frequencies: from earthquake noise at 5 Hz to harbor porpoise clicks at 
150,000 Hz (150 kHz). These sounds are so low or so high in pitch that 
humans cannot even hear them; acousticians call these infrasonic and 
ultrasonic sounds, respectively. A single sound may be made up of many 
different frequencies together. Sounds made up of only a small range of 
frequencies are called ``narrowband,'' and sounds with a broad range of 
frequencies are called ``broadband;'' airguns are an example of a 
broadband sound source and tactical sonars are an example of a 
narrowband sound source.
    When considering the influence of various kinds of sound on the 
marine environment, it is necessary to understand that different kinds 
of marine life are sensitive to different frequencies of sound. Based 
on available behavioral data, audiograms derived using auditory evoked 
potential, anatomical modeling, and other data, Southall et al. (2007) 
designate ``functional hearing groups'' and estimate the lower and 
upper frequencies of functional hearing of the groups. Further, the 
frequency range in which each group's hearing is estimated as being 
most sensitive is represented in the flat part of the M-weighting 
functions developed for each group. The functional groups and the 
associated frequencies are indicated below:
     Low-frequency cetaceans (13 species of mysticetes): 
Functional hearing is estimated to occur between approximately 7 Hz and 
22 kHz.
     Mid-frequency cetaceans (32 species of dolphins, six 
species of larger toothed whales, and 19 species of beaked and 
bottlenose whales): Functional hearing is estimated to occur between 
approximately 150 Hz and 160 kHz.
     High-frequency cetaceans (eight species of true porpoises, 
six species of river dolphins, Kogia, the franciscana, and four species 
of cephalorhynchids): Functional hearing is estimated to occur between 
approximately 200 Hz and 180 kHz.
     Pinnipeds in Water: Functional hearing is estimated to 
occur between approximately 75 Hz and 75 kHz, with the greatest 
sensitivity between approximately 700 Hz and 20 kHz.
     Pinnipeds in Air: Functional hearing is estimated to occur 
between approximately 75 Hz and 30 kHz.
    Because ears adapted to function underwater are physiologically 
different from human ears, comparisons using decibel measurements in 
air would still not be adequate to describe the effects of a sound on a 
whale. When sound travels away from its source, its loudness decreases 
as the distance traveled (propagates) by the sound increases. Thus, the 
loudness of a sound at its source is higher than the loudness of that 
same sound a kilometer distant. Acousticians often refer to the 
loudness of a sound at its source (typically measured one meter from 
the source) as the source level and the loudness of sound elsewhere as 
the received level. For example, a humpback whale three kilometers from 
an airgun that has a source level of 230 dB may only be exposed to 
sound that is 160 dB loud, depending on how the sound propagates. As a 
result, it is important not to confuse source levels and received 
levels when discussing the loudness of sound in the ocean.
    As sound travels from a source, its propagation in water is 
influenced by various physical characteristics, including water 
temperature, depth, salinity, and surface and bottom properties that 
cause refraction, reflection, absorption, and scattering of sound 
waves. Oceans are not homogeneous and the contribution of each of these 
individual factors is extremely complex and interrelated. The physical 
characteristics that determine the sound's speed through the water will 
change with depth, season, geographic location, and with time of day 
(as a result, in actual sonar operations, crews will measure oceanic 
conditions, such as sea water temperature and depth, to calibrate 
models that determine the path the sonar signal will take as it travels 
through the ocean and how strong the sound signal will be at a given 
range along a particular transmission path). As sound travels through 
the ocean, the intensity associated with the wavefront diminishes, or 
attenuates. This decrease in intensity is referred to as propagation 
loss, also commonly called transmission loss.

Metrics Used in This Document

    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 microPa, where 1 Pa is the pressure resulting from a force 
of one newton exerted over an area of one square meter. 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 [micro]Pa, and the units for SPLs are dB re: 1 
[micro]Pa.

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

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square root of the arithmetic average of the squared instantaneous 
pressure values, is typically used in discussions of the effects of 
sounds on vertebrates and all references to SPL in this document refer 
to the root mean square. SPL does not take the duration of a sound into 
account. SPL is the applicable metric used in the risk continuum, which 
is used to estimate behavioral harassment takes (see Level B Harassment 
Risk Function (Behavioral Harassment) Section).
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 microPa\2\-s.

SEL = SPL + 10 log(duration in seconds)

    As applied to tactical sonar, the SEL includes both the SPL of a 
sonar ping and the total duration. Longer duration pings and/or pings 
with higher SPLs 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. The total SEL depends on the SPL, duration, and number 
of pings received. The thresholds that NMFS uses to indicate at what 
received level the onset of temporary threshold shift (TTS) and 
permanent threshold shift (PTS) in hearing are likely to occur are 
expressed in SEL.

Potential Impacts to Marine Mammal Species

    The Navy considers that the Q-20 sonar testing activities in the Q-
20 Study Area could potentially result in harassment to marine mammals. 
Although surface operations related to sonar testing involve ship 
movement in the vicinity of the Q-20 test area, NMFS considers it 
unlikely that ship strike could occur as analyzed in the Federal 
Register for the proposed IHA (77 FR 12010; February 28, 2012).
    Anticipated impacts resulting from the Navy's Q-20 testing 
activities primary arise from underwater noise due to sonar operations, 
if marine mammals are in the vicinity of the action area. The following 
subsection provides a summary of the acoustic effects to marine 
mammals.
(1) Direct Physiological Effects
    Based on the literature, there are two basic ways that Navy sonar 
might directly result in physical trauma or damage: Noise-induced loss 
of hearing sensitivity (more commonly-called ``threshold shift'') and 
acoustically mediated bubble growth. Separately, an animal's behavioral 
reaction to an acoustic exposure might lead to physiological effects 
that might ultimately lead to injury or death, which is discussed later 
in the Stranding section.

Threshold Shift (Noise-Induced Loss of Hearing)

    When animals exhibit reduced hearing sensitivity (i.e., sounds must 
be louder for an animal to recognize them) following exposure to a 
sufficiently intense sound, it is referred to as a noise-induced 
threshold shift (TS). An animal can experience temporary threshold 
shift (TTS) or permanent threshold shift (PTS). TTS can last from 
minutes or hours to days (i.e., there is recovery), occurs in specific 
frequency ranges (e.g., an animal might only have a temporary loss of 
hearing sensitivity between the frequencies of 1 and 10 kHz), and can 
be of varying amounts (for example, an animal's hearing sensitivity 
might be reduced by only 6 dB or reduced by 30 dB). PTS is permanent 
(i.e., there is no recovery), but also occurs in a specific frequency 
range and amount as mentioned in the TTS description.
    The following physiological mechanisms are thought to play a role 
in inducing auditory TSs: Effects on sensory hair cells in the inner 
ear that reduce their sensitivity, modification of the chemical 
environment within the sensory cells, residual muscular activity in the 
middle ear, displacement of certain inner ear membranes, increased 
blood flow, and post-stimulatory reduction in both efferent and sensory 
neural output (Southall et al., 2007). The amplitude, duration, 
frequency, temporal pattern, and energy distribution of sound exposure 
all affect the amount of associated TS and the frequency range in which 
it occurs. As amplitude and duration of sound exposure increase, so, 
generally, does the amount of TS. For continuous sounds, exposures of 
equal energy (the same SEL) will lead to approximately equal effects. 
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). For example, one short 
but loud (higher SPL) sound exposure may induce the same impairment as 
one longer but softer sound, which in turn may cause more impairment 
than a series of several intermittent softer sounds with the same total 
energy (Ward, 1997). Additionally, though TTS is temporary, very 
prolonged exposure to sound strong enough to elicit TTS, or shorter-
term exposure to sound levels well above the TTS threshold, can cause 
PTS, at least in terrestrial mammals (Kryter, 1985) (although in the 
case of Navy sonar, animals are not expected to be exposed to levels 
high enough or durations long enough to result in PTS).
    PTS is considered auditory injury (Southall et al., 2007). 
Irreparable damage to the inner or outer cochlear hair cells may cause 
PTS, however, other mechanisms are also involved, such as exceeding the 
elastic limits of certain tissues and membranes in the middle and inner 
ears and resultant changes in the chemical composition of the inner ear 
fluids (Southall et al., 2007).
    Although the published body of scientific literature contains 
numerous theoretical studies and discussion papers on hearing 
impairments that can occur with exposure to a loud sound, only a few 
studies provide empirical information on the levels at which noise-
induced loss in hearing sensitivity occurs in nonhuman animals. For 
cetaceans, published data are limited to the captive bottlenose dolphin 
and beluga whale (Finneran et al., 2000, 2002b, 2005a; Schlundt et al., 
2000; Nachtigall et al., 2003, 2004).
    Marine mammal hearing plays a critical role in communication with 
conspecifics, and interpreting environmental cues for purposes such as 
predator avoidance and prey capture. Depending on the frequency range 
of TTS degree (dB), duration, and frequency range of TTS, and the 
context in which it is experienced, TTS can have effects on marine 
mammals ranging from discountable to serious (similar to those 
discussed in auditory masking, below). For example, a marine mammal may 
be able to readily compensate for a brief, relatively small amount of 
TTS in a non-critical frequency range that takes place during a time 
when the animal is traveling through the open ocean, where ambient 
noise is lower and there are not as many competing sounds present.
    Alternatively, a larger amount and longer duration of TTS sustained 
during a time when communication is critical for successful mother/calf 
interactions could have more serious impacts. Also, depending on the 
degree and frequency range, the effects of PTS on an animal could range 
in severity, although it is considered generally more serious because 
it is a long term condition. Of note, reduced hearing sensitivity as a 
simple function of development and aging has been observed in marine 
mammals, as well as humans and other taxa (Southall et al., 2007), so 
we can infer that strategies exist for coping with this condition to 
some degree, though likely not without cost. There is no empirical 
evidence that exposure to

[[Page 49416]]

Navy sonar can cause PTS in any marine mammals; instead the probability 
of PTS has been inferred from studies of TTS (see Richardson et al., 
1995).

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., 2001). 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. Recent work conducted by Crum et al. (2005) 
demonstrated the possibility of rectified diffusion for short duration 
signals, but at sound exposure levels and tissue saturation levels that 
are improbable to occur in a diving marine mammal. 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 (decompression 
sickness) 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; 
Fernandez et al., 2005). 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). Crum and Mao (1996) hypothesized that received 
levels would have to exceed 190 dB in order for there to be the 
possibility of significant bubble growth due to supersaturation of 
gases in the blood (i.e., rectified diffusion). More recent work 
conducted by Crum et al. (2005) demonstrated the possibility of 
rectified diffusion for short duration signals, but at SELs and tissue 
saturation levels that are highly improbable to occur in diving marine 
mammals. To date, Energy Levels (ELs) predicted to cause in vivo bubble 
formation within diving cetaceans have not been evaluated (NOAA, 2002). 
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 (Hooker et al., 2011). However, Jepson et al. (2003, 2005) and 
Fernandez et al. (2004, 2005) concluded that in vivo bubble formation, 
which may be exacerbated by deep, long duration, repetitive dives may 
explain why beaked whales appear to be particularly vulnerable to sonar 
exposures. A recent review of evidence for gas-bubble incidence in 
marine mammal tissues suggest that diving mammals vary their 
physiological responses according to multiple stressors, and that the 
perspective on marine mammal diving physiology should change from 
simply minimizing nitrogen loading to management of the nitrogen load 
(Hooker et al., 2011). This suggests several avenues for further study, 
ranging from the effects of gas bubbles at molecular, cellular and 
organ function levels, to comparative studies relating the presence/
absence of gas bubbles to diving behavior. More information regarding 
hypotheses that attempt to explain how behavioral responses to Navy 
sonar can lead to strandings is included in the Behaviorally Mediated 
Bubble Growth section, after the summary of strandings.
(2) Acoustic Masking
    Marine mammals use acoustic signals for a variety of purposes, 
which differ among species, but include communication between 
individuals, navigation, foraging, reproduction, and learning about 
their environment (Erbe and Farmer, 2000; Tyack, 2000; Clark et al., 
2009). Masking, or auditory interference, generally occurs when sounds 
in the environment are louder than, and of a similar frequency to, 
auditory signals an animal is trying to receive. Masking is a 
phenomenon that affects animals that are trying to receive acoustic 
information about their environment, including sounds from other 
members of their species, predators, prey, and sounds that allow them 
to orient in their environment. Masking these acoustic signals can 
disturb the behavior of individual animals, groups of animals, or 
entire populations.
    The extent of the masking interference depends on the spectral, 
temporal, and spatial relationships between the signals an animal is 
trying to receive and the masking noise, in addition to other factors. 
In humans, significant masking of tonal signals occurs as a result of 
exposure to noise in a narrow band of similar frequencies. As the sound 
level increases, though, the detection of frequencies above those of 
the masking stimulus also decreases. This principle is also expected to 
apply to marine mammals because of common biomechanical cochlear 
properties across taxa.
    Richardson et al. (1995) argued that the maximum radius of 
influence of an industrial noise (including broadband low frequency 
sound transmission) on a marine mammal is the distance from the source 
to the point at which the noise can barely be heard. This range is 
determined by either the hearing sensitivity of the animal or the 
background noise level present. Industrial masking is most likely to 
affect some species' ability to detect communication calls and natural 
sounds (i.e., surf noise, prey noise, etc.; Richardson et al., 1995).
    The echolocation calls of odontocetes (toothed whales) are subject 
to masking by high frequency sound. Human data indicate low-frequency 
sound can mask high-frequency sounds (i.e., upward masking). Studies on 
captive odontocetes by Au et al. (1974, 1985, 1993) indicate that some 
species may use various processes to reduce masking effects (e.g., 
adjustments in echolocation call intensity or frequency as a function 
of background noise conditions). There is also evidence that the 
directional hearing abilities of odontocetes are useful in reducing 
masking at the high frequencies these cetaceans use to echolocate, but 
not at the low-to-moderate frequencies they use to communicate 
(Zaitseva et al., 1980).
    As mentioned previously, the functional hearing ranges of 
mysticetes (baleen whales) and odontocetes (toothed whales) all 
encompass the

[[Page 49417]]

frequencies of the sonar sources used in the Navy's Q-20 test 
activities. Additionally, almost all species' vocal repertoires span 
across the frequencies of the sonar sources used by the Navy. The 
closer the characteristics of the masking signal to the signal of 
interest, the more likely masking is to occur. However, because the 
pulse length and duty cycle of the Navy sonar signals are of short 
duration and would not be continuous, masking is unlikely to occur as a 
result of exposure to these signals during the Q-20 test activities in 
the designated Q-20 Study Area.
    In addition to making it more difficult for animals to perceive 
acoustic cues in their environment, anthropogenic sound presents 
separate challenges for animals that are vocalizing. When they 
vocalize, animals are aware of environmental conditions that affect the 
``active space'' of their vocalizations, which is the maximum area 
within which their vocalizations can be detected before it drops to the 
level of ambient noise (Brenowitz, 2004; Brumm et al., 2004; Lohr et 
al., 2003). Animals are also aware of environmental conditions that 
affect whether listeners can discriminate and recognize their 
vocalizations from other sounds, which are more important than 
detecting a vocalization (Brenowitz, 1982; Brumm et al., 2004; Dooling, 
2004; Marten and Marler, 1977; Patricelli et al., 2006). Most animals 
that vocalize have evolved an ability to make vocal adjustments to 
their vocalizations to increase the signal-to-noise ratio, active 
space, and recognizability of their vocalizations in the face of 
temporary changes in background noise (Brumm et al., 2004; Patricelli 
et al., 2006). Vocalizing animals will make one or more of the 
following adjustments to their vocalizations: Adjust the frequency 
structure; adjust the amplitude; adjust temporal structure; or adjust 
temporal delivery.
    Many animals will combine several of these strategies to compensate 
for high levels of background noise. Anthropogenic sounds that reduce 
the signal-to-noise ratio of animal vocalizations, increase the masked 
auditory thresholds of animals listening for such vocalizations, or 
reduce the active space of an animal's vocalizations impair 
communication between animals. Most animals that vocalize have evolved 
strategies to compensate for the effects of short-term or temporary 
increases in background or ambient noise on their songs or calls. 
Although the fitness consequences of these vocal adjustments remain 
unknown, like most other trade-offs animals must make, some of these 
strategies probably come at a cost (Patricelli et al., 2006). For 
example, vocalizing more loudly in noisy environments may have 
energetic costs that decrease the net benefits of vocal adjustment and 
alter a bird's energy budget (Brumm, 2004; Wood and Yezerinac, 2006). 
Shifting songs and calls to higher frequencies may also impose 
energetic costs (Lambrechts, 1996).
(3) Stress Responses
    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 (Moberg, 2000; Sapolsky et al., 2005; Seyle, 
1950). Once an animal's central nervous system perceives a threat, it 
mounts 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 
responses.
    In the case of many stressors, an animal's first and most 
economical (in terms of biotic costs) response is behavioral avoidance 
of the potential stressor or avoidance of continued exposure to a 
stressor. An animal's second line of defense to stressors involves the 
autonomic nervous system and the classical ``fight or flight'' 
response, which includes the cardiovascular system, the 
gastrointestinal system, the exocrine glands, and the adrenal medulla 
to produce changes in heart rate, blood pressure, and gastrointestinal 
activity that humans commonly associate with ``stress.'' These 
responses have a relatively short duration and may or may not have 
significant long-term effects on an animal's welfare.
    An animal's third line of defense to stressors involves its 
neuroendocrine or sympathetic nervous systems; the system that has 
received the most study has been the hypothalmus-pituitary-adrenal 
system (also known as the HPA axis in mammals or the hypothalamus-
pituitary-interrenal axis in fish and some reptiles). Unlike stress 
responses associated with the autonomic nervous system, virtually all 
neuro-endocrine functions that are affected by stress--including immune 
competence, reproduction, metabolism, and behavior--are regulated by 
pituitary hormones. Stress-induced changes in the secretion of 
pituitary hormones have been implicated in failed reproduction (Moberg, 
1987; Rivier, 1995) and altered metabolism (Elasser et al., 2000), 
reduced immune competence (Blecha, 2000) and behavioral disturbance. 
Increases in the circulation of glucocorticosteroids (cortisol, 
corticosterone, and aldosterone in marine mammals; Romano et al., 2004) 
have been equated with stress for many years.
    The primary distinction between stress (which is adaptive and does 
not normally place an animal at risk) and distress is the biotic cost 
of the response. During a stress response, an animal uses glycogen 
stores that can be quickly replenished once the stress is alleviated. 
In such circumstances, the cost of the stress response would not pose a 
risk to the animal's welfare. However, when an animal does not have 
sufficient energy reserves to satisfy the energetic costs of a stress 
response, energy resources must be diverted from other biotic 
functions, which impair those functions that experience the diversion. 
For example, when mounting a stress response diverts energy away from 
growth in young animals, those animals may experience stunted growth. 
When mounting a stress response diverts energy from a fetus, an 
animal's reproductive success and its fitness will suffer. In these 
cases, the animals will have entered a pre-pathological or pathological 
state which is called ``distress'' (sensu Seyle, 1950) or ``allostatic 
loading'' (sensu McEwen and Wingfield, 2003). This pathological state 
will last until the animal replenishes its biotic reserves sufficient 
to restore normal function.
    Relationships between these physiological mechanisms, animal 
behavior, and the costs of stress responses have also been documented 
fairly well through controlled experiments; because this physiology 
exists in every vertebrate that has been studied, it is not surprising 
that stress responses and their costs have been documented 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). Although no information has been collected on the physiological 
responses of marine mammals to exposure to anthropogenic sounds, 
studies of other marine animals and terrestrial animals would lead us 
to expect some marine mammals to experience physiological stress 
responses and, perhaps, physiological responses that would be 
classified as ``distress'' upon exposure to mid-frequency and low-
frequency sounds.
    For example, Jansen (1998) reported on the relationship between 
acoustic

[[Page 49418]]

exposures and physiological responses that are indicative of stress 
responses in humans (for example, elevated respiration and increased 
heart rates). Jones (1998) reported on reductions in human performance 
when faced with acute, repetitive exposures to acoustic disturbance. 
Trimper et al. (1998) reported on the physiological stress responses of 
osprey to low-level aircraft noise while Krausman et al. (2004) 
reported on the auditory and physiology stress responses of endangered 
Sonoran pronghorn to military overflights. Smith et al. (2004a, 2004b) 
identified noise induced physiological transient stress responses in 
hearing-specialist fish that accompanied short- and long-term hearing 
losses. Welch and Welch (1970) reported physiological and behavioral 
stress responses that accompanied damage to the inner ears of fish and 
several mammals.
    Hearing is one of the primary senses cetaceans use to gather 
information about their environment and to communicate with 
conspecifics. Although empirical information on the relationship 
between sensory impairment (TTS, PTS, and acoustic masking) on 
cetaceans remains limited, it seems reasonable to assume that reducing 
an animal's ability to gather information about its environment and to 
communicate with other members of its species would be stressful for 
animals that use hearing as their primary sensory mechanism. Therefore, 
we assume that acoustic exposures sufficient to trigger onset PTS or 
TTS would be accompanied by physiological stress responses because 
terrestrial animals exhibit those responses under similar conditions 
(NRC, 2003). More importantly, marine mammals might experience stress 
responses at received levels lower than those necessary to trigger 
onset TTS. Based on empirical studies of the time required to recover 
from stress responses (Moberg, 2000), we also assume that stress 
responses are likely to persist beyond the time interval required for 
animals to recover from TTS and might result in pathological and pre-
pathological states that would be as significant as behavioral 
responses to TTS.
(4) Behavioral Disturbance
    Behavioral responses to sound are highly variable and context-
specific. Exposure of marine mammals to sound sources can result in 
(but is not limited to) the following observable responses: Increased 
alertness; orientation or attraction to a sound source; vocal 
modifications; cessation of feeding; cessation of social interaction; 
alteration of movement or diving behavior; habitat abandonment 
(temporary or permanent); and, in severe cases, panic, flight, 
stampede, or stranding, potentially resulting in death (Southall et 
al., 2007).
    Many different variables can influence an animal's perception of 
and response to (nature and magnitude) an acoustic event. An animal's 
prior experience with a sound type affects whether it is less likely 
(habituation) or more likely (sensitization) to respond to certain 
sounds in the future (animals can also be innately pre-disposed to 
respond to certain sounds in certain ways) (Southall et al., 2007). 
Related to the sound itself, the perceived nearness of the sound, 
bearing of the sound (approaching vs. retreating), similarity of a 
sound to biologically relevant sounds in the animal's environment 
(i.e., calls of predators, prey, or conspecifics), and familiarity of 
the sound may affect the way an animal responds to the sound (Southall 
et al., 2007). Individuals (of different age, gender, reproductive 
status, etc.) among most populations will have variable hearing 
capabilities, and differing behavioral sensitivities to sounds that 
will be affected by prior conditioning, experience, and current 
activities of those individuals. Often, specific acoustic features of 
the sound and contextual variables (i.e., proximity, duration, or 
recurrence of the sound or the current behavior that the marine mammal 
is engaged in or its prior experience), as well as entirely separate 
factors such as the physical presence of a nearby vessel, may be more 
relevant to the animal's response than the received level alone.
    There are only few empirical studies of behavioral responses of 
free-living cetaceans to military sonar being conducted to date, due to 
the difficulties in implementing experimental protocols on wild marine 
mammals.
    An opportunistic observation was made on a tagged Blainville's 
beaked whale (Mesoplodon densirostris) before, during, and after a 
multi-day naval exercise involving tactical mid-frequency sonars within 
the U.S. Navy's sonar testing range at the Atlantic Undersea Test and 
Evaluation Center (AUTEC), in the Tongue of the Ocean near Andros 
Island in the Bahamas (Tyack et al., 2011). The adult male whale was 
tagged with a satellite transmitter tag on May 7, 2009. During the 72 
hrs before the sonar exercise started, the mean distance from whale to 
the center of the AUTEC range was approximately 37 km. During the 72 
hrs sonar exercise, the whale moved several tens of km farther away 
(mean distance approximately 54 km). The received sound levels at the 
tagged whale during sonar exposure were estimated to be 146 dB re 1 
[mu]Pa at the highest level. The tagged whale slowly returned for 
several days (mean distance approximately 29 km) from 0-72 hours after 
the exercise stopped (Tyack et al., 2011).
    In the past several years, controlled exposure experiments (CEE) on 
marine mammal behavioral responses to military sonar signals using 
acoustic tags have been started in the Bahamas, the Mediterranean Sea, 
southern California, and Norway. These behavioral response studies 
(BRS), though still in their early stages, have provided some 
preliminary insights into cetacean behavioral disturbances when exposed 
to simulated and actual military sonar signals.
    In 2007 and 2008, two Blainville's beaked whales were tagged in the 
AUTEC range and exposed to simulated mid-frequency sonar signals, 
killer whale (Orcinus orca) recordings (in 2007), and pseudo-random 
noise (PRN, in 2008) (Tyack et al., 2011). For the simulated mid-
frequency exposure BRS, the tagged whale stopped clicking during its 
foraging dive after 9 minutes when the received level reached 138 dB 
SPL, or a cumulative SEL value of 142 dB re 1 [mu]Pa\2\-s. Once the 
whale stopped clicking, it ascended slowly, moving away from the sound 
source. The whale surfaced and remained in the area for approximately 2 
hours before making another foraging dive (Tyack et al., 2011).
    The same beaked whale was exposed to a killer whale sound recording 
during its subsequent deep foraging dive. The whale stopped clicking 
about 1 minute after the received level of the killer whale sound 
reached 98 dB SPL, just above the ambient noise level at the whale. The 
whale then made a long and slow ascent. After surfacing, the whale 
continued to swim away from the playback location for 10 hours (Tyack 
et al., 2011).
    In 2008, a Blainville's beaked was tagged and exposed with PRN that 
has the same frequency band as the simulated mid-frequency sonar 
signal. The received level at the whale ranged from inaudible to 142 dB 
SPL (144 dB cumulative SEL). The whale stopped clicking less than 2 
minutes after exposure to the last transmission and ascended slowly to 
approximately 600 m. The whale appeared to stop at this depth, at which 
time the tag unexpectedly released from the whale (Tyack et al., 2011).
    During CEEs of the BRS off Norway, social behavioral responses of 
pilot whales and killer whales to tagging and sonar exposure were 
investigated. Sonar exposure was sampled for 3 pilot whale

[[Page 49419]]

(Globicephala spp.) groups and 1 group of killer whales. Results show 
that when exposed to sonar signals, pilot whales showed a preference 
for larger groups with medium-low surfacing synchrony, while starting 
logging, spyhopping and milling. Killer whales showed the opposite 
pattern, maintaining asynchronous patterns of surface behavior: 
decreased surfacing synchrony, increased spacing, decreased group size, 
tailslaps and loggings (Visser et al., 2011).
    Although the small sample size of these CEEs reported here is too 
small to make firm conclusions about differential responses of 
cetaceans to military sonar exposure, none of the results showed that 
whales responded to sonar signals with panicked flight. Instead, the 
beaked whales exposed to simulated sonar signals and killer whale sound 
recording moved in a well oriented direction away from the source 
towards the deep water exit from the Tongue of the Ocean (Tyack et al., 
2011). In addition, different species of cetaceans exhibited different 
social behavioral responses towards (close) vessel presence and sonar 
signals, which elicit different, potentially tailored and species-
specific responses (Visser et al., 2011).
    Much more qualitative information is available on the avoidance 
responses of free-living cetaceans to other acoustic sources, like 
seismic airguns and low-frequency active sonar, than mid-frequency 
active sonar. Richardson et al., (1995) noted that avoidance reactions 
are the most obvious manifestations of disturbance in marine mammals.

Behavioral Responses

    Southall et al., (2007) reports the results of the efforts of a 
panel of experts in acoustic research from behavioral, physiological, 
and physical disciplines that convened and reviewed the available 
literature on marine mammal hearing and physiological and behavioral 
responses to man-made sound with the goal of proposing exposure 
criteria for certain effects. This compilation of literature is very 
valuable, though Southall et al. note that not all data is equal, some 
have poor statistical power, insufficient controls, and/or limited 
information on received levels, background noise, and other potentially 
important contextual variables--such data were reviewed and sometimes 
used for qualitative illustration, but were not included in the 
quantitative analysis for the criteria recommendations.
    In the Southall et al., (2007) report, for the purposes of 
analyzing responses of marine mammals to anthropogenic sound and 
developing criteria, the authors differentiate between single pulse 
sounds, multiple pulse sounds, and non-pulse sounds. HFAS/MFAS sonar is 
considered a non-pulse sound. Southall et al., (2007) summarize the 
reports associated with low-, mid-, and high-frequency cetacean 
responses to non-pulse sounds (there are no pinnipeds in the Gulf of 
Mexico (GOM)) in Appendix C of their report (incorporated by reference 
and summarized in the three paragraphs below).
    The reports that address responses of low-frequency cetaceans to 
non-pulse sounds include data gathered in the field and related to 
several types of sound sources (of varying similarity to HFAS/MFAS) 
including: Vessel noise, drilling and machinery playback, low frequency 
M-sequences (sine wave with multiple phase reversals) playback, low 
frequency active sonar playback, drill vessels, Acoustic Thermometry of 
Ocean Climate (ATOC) source, and non-pulse playbacks. These reports 
generally indicate no (or very limited) responses to received levels in 
the 90 to 120 dB re 1 [mu]Pa range and an increasing likelihood of 
avoidance and other behavioral effects in the 120 to 160 dB range. As 
mentioned earlier, however, contextual variables play a very important 
role in the reported responses and the severity of effects are not 
linear when compared to received level. Also, few of the laboratory or 
field datasets had common conditions, behavioral contexts or sound 
sources, so it is not surprising that responses differ.
    The reports that address responses of mid-frequency cetaceans to 
non-pulse sounds include data gathered both in the field and the 
laboratory and related to several different sound sources (of varying 
similarity to HFAS/MFAS) including: Pingers, drilling playbacks, vessel 
and ice-breaking noise, vessel noise, Acoustic Harassment Devices 
(AHDs), Acoustic Deterrent Devices (ADDs), HFAS/MFAS, and non-pulse 
bands and tones. Southall et al. were unable to come to a clear 
conclusion regarding these reports. In some cases, animals in the field 
showed significant responses to received levels between 90 and 120 dB, 
while in other cases these responses were not seen in the 120 to 150 dB 
range. The disparity in results was likely due to contextual variation 
and the differences between the results in the field and laboratory 
data (animals responded at lower levels in the field).
    The reports that address the responses of high-frequency cetaceans 
to non-pulse sounds include data gathered both in the field and the 
laboratory and related to several different sound sources (of varying 
similarity to HFAS/MFAS) including: acoustic harassment devices, 
Acoustical Telemetry of Ocean Climate (ATOC), wind turbine, vessel 
noise, and construction noise. However, no conclusive results are 
available from these reports. In some cases, high frequency cetaceans 
(harbor porpoises) are observed to be quite sensitive to a wide range 
of human sounds at very low exposure RLs (90 to 120 dB). All recorded 
exposures exceeding 140 dB produced profound and sustained avoidance 
behavior in wild harbor porpoises (Southall et al., 2007).
    In addition to summarizing the available data, the authors of 
Southall et al. (2007) developed a severity scaling system with the 
intent of ultimately being able to assign some level of biological 
significance to a response. Following is a summary of their scoring 
system, a comprehensive list of the behaviors associated with each 
score may be found in the report:
     0-3 (Minor and/or brief behaviors) includes, but is not 
limited to: No response; minor changes in speed or locomotion (but with 
no avoidance); individual alert behavior; minor cessation in vocal 
behavior; minor changes in response to trained behaviors (in 
laboratory).
     4-6 (Behaviors with higher potential to affect foraging, 
reproduction, or survival) includes, but is not limited to: Moderate 
changes in speed, direction, or dive profile; brief shift in group 
distribution; prolonged cessation or modification of vocal behavior 
(duration > duration of sound); minor or moderate individual and/or 
group avoidance of sound; brief cessation of reproductive behavior; or 
refusal to initiate trained tasks (in laboratory).
     7-9 (Behaviors considered likely to affect the 
aforementioned vital rates) includes, but are not limited to: Extensive 
of prolonged aggressive behavior; moderate, prolonged or significant 
separation of females and dependent offspring with disruption of 
acoustic reunion mechanisms; long-term avoidance of an area; outright 
panic, stampede, stranding; threatening or attacking sound source (in 
laboratory).
    In Table 2 we have summarized the scores that Southall et al. 
(2007) assigned to the papers that reported behavioral responses of 
low-frequency cetaceans, mid-frequency cetaceans, and high-frequency 
cetaceans to non-pulse sounds.

[[Page 49420]]



 Table 4--Data Compiled From Three Tables From Southall et al. (2007) Indicating When Marine Mammals (Low-Frequency Cetacean = L, Mid-Frequency Cetacean
   = M, and High-Frequency Cetacean = H) Were Reported as Having a Behavioral Response of the Indicated Severity to a Non-Pulse Sound of the Indicated
                                                                     Received Level
                                     [As discussed in the text, responses are highly variable and context specific]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                    Received RMS Sound Pressure Level (dB re 1 microPa)
                                 -----------------------------------------------------------------------------------------------------------------------
         Response score             80 to     90 to    100 to    110 to    120 to    130 to    140 to    150 to    160 to    170 to    180 to    190 to
                                     <90      <100      <110      <120      <130      <140      <150      <160      <170      <180      <190      <200
--------------------------------------------------------------------------------------------------------------------------------------------------------
9...............................  ........  ........  ........  ........  ........  ........  ........  ........  ........  ........  ........  ........
8...............................  ........        M         M   ........        M   ........        M   ........  ........  ........        M         M
7...............................  ........  ........  ........  ........  ........        L         L   ........  ........  ........  ........  ........
6...............................        H       L/H       L/H     L/M/H     L/M/H         L       L/H         H       M/H         M   ........  ........
5...............................  ........  ........  ........  ........        M   ........  ........  ........  ........  ........  ........  ........
4...............................  ........  ........        H     L/M/H       L/M   ........        L   ........  ........  ........  ........  ........
3...............................  ........        M       L/M       L/M         M   ........  ........  ........  ........  ........  ........  ........
2...............................  ........  ........        L       L/M         L         L         L   ........  ........  ........  ........  ........
1...............................  ........  ........        M         M         M   ........  ........  ........  ........  ........  ........  ........
0...............................      L/H       L/H     L/M/H     L/M/H     L/M/H         L         M   ........  ........  ........        M         M
--------------------------------------------------------------------------------------------------------------------------------------------------------

Potential Effects of Behavioral Disturbance

    The different ways that marine mammals respond to sound are 
sometimes indicators of the ultimate effect that exposure to a given 
stimulus will have on the well-being (survival, reproduction, etc.) of 
an animal. There is little marine mammal data quantitatively relating 
the exposure of marine mammals to sound to effects on reproduction or 
survival, though data exists for terrestrial species to which we can 
draw comparisons for marine mammals.
    Attention is the cognitive process of selectively concentrating on 
one aspect of an animal's environment while ignoring other things 
(Posner, 1994). Because animals (including humans) have limited 
cognitive resources, there is a limit to how much sensory information 
they can process at any time. The phenomenon called ``attentional 
capture'' occurs when a stimulus (usually a stimulus that an animal is 
not concentrating on or attending to) ``captures'' an animal's 
attention. This shift in attention can occur consciously or 
unconsciously (for example, when an animal hears sounds that it 
associates with the approach of a predator) and the shift in attention 
can be sudden (Dukas, 2002; van Rij, 2007). Once a stimulus has 
captured an animal's attention, the animal can respond by ignoring the 
stimulus, assuming a ``watch and wait'' posture, or treat the stimulus 
as a disturbance and respond accordingly, which includes scanning for 
the source of the stimulus or ``vigilance'' (Cowlishaw et al., 2004).
    Vigilance is normally an adaptive behavior that helps animals 
determine the presence or absence of predators, assess their distance 
from conspecifics, or to attend cues from prey (Bednekoff and Lima, 
1998; Treves, 2000). Despite those benefits, however, vigilance has a 
cost of time: When animals focus their attention on specific 
environmental cues, they are not attending to other activities such a 
foraging. These costs have been documented best in foraging animals, 
where vigilance has been shown to substantially reduce feeding rates 
(Saino, 1994; Beauchamp and Livoreil, 1997; Fritz et al., 2002).
    Animals will spend more time being vigilant, which may translate to 
less time foraging or resting, when disturbance stimuli approach them 
more directly, remain at closer distances, have a greater group size 
(for example, multiple surface vessels), or when they co-occur with 
times that an animal perceives increased risk (for example, when they 
are giving birth or accompanied by a calf). Most of the published 
literature, however, suggests that direct approaches will increase the 
amount of time animals will dedicate to being vigilant. For example, 
bighorn sheep and Dall's sheep dedicated more time being vigilant, and 
less time resting or foraging, when aircraft made direct approaches 
over them (Frid, 2001; Stockwell et al., 1991).
    Several authors have established that long-term and intense 
disturbance stimuli can cause population declines by reducing the body 
condition of individuals that have been disturbed, followed by reduced 
reproductive success, reduced survival, or both (Daan et al., 1996; 
Madsen, 1994; White, 1983). For example, Madsen (1994) reported that 
pink-footed geese (Anser brachyrhynchus) in undisturbed habitat gained 
body mass and had about a 46-percent reproductive success compared with 
geese in disturbed habitat (being consistently scared off the fields on 
which they were foraging), which did not gain mass and had a 17 percent 
reproductive success. Similar reductions in reproductive success have 
been reported for mule deer (Odocoileus hemionus) disturbed by all-
terrain vehicles (Yarmoloy et al., 1988), caribou disturbed by seismic 
exploration blasts (Bradshaw et al., 1998), caribou disturbed by low-
elevation military jetfights (Luick et al., 1996), and caribou 
disturbed by low-elevation jet flights (Harrington and Veitch, 1992). 
Similarly, a study of elk (Cervus elaphus) that were disturbed 
experimentally by pedestrians concluded that the ratio of young to 
mothers was inversely related to disturbance rate (Phillips and 
Alldredge, 2000).
    The primary mechanism by which increased vigilance and disturbance 
appear to affect the fitness of individual animals is by disrupting an 
animal's time budget and, as a result, reducing the time they might 
spend foraging and resting (which increases an animal's activity rate 
and energy demand). For example, a study of grizzly bears (Ursus 
horribilis) reported that bears disturbed by hikers reduced their 
energy intake by an average of 12 kcal/min (50.2 x 103kJ/min), and 
spent energy fleeing or acting aggressively toward hikers (White et 
al., 1999).
    On a related note, many animals perform vital functions, such as 
feeding, resting, traveling, and socializing, on a diel cycle (24-hr 
cycle). Substantive behavioral reactions to noise exposure (such as 
disruption of critical life functions, displacement, or avoidance of 
important habitat) are more likely to be significant if they last more 
than one

[[Page 49421]]

diel cycle or recur on subsequent days (Southall et al., 2007). 
Consequently, a behavioral response lasting less than one day and not 
recurring on subsequent days is not considered particularly severe 
unless it could directly affect reproduction or survival (Southall et 
al., 2007).
(5) Stranding and Mortality
    When a live or dead marine mammal swims or floats onto shore and 
becomes ``beached'' or incapable of returning to sea, the event is 
termed a ``stranding'' (Geraci et al., 1999; Perrin and Geraci, 2002; 
Geraci and Lounsbury, 2005; NMFS, 2007). Marine mammals are known to 
strand for a variety of reasons, such as infectious agents, 
biotoxicosis, starvation, fishery interaction, ship strike, unusual 
oceanographic or weather events, sound exposure, or combinations of 
these stressors sustained concurrently or in series. However, the cause 
or causes of most stranding are unknown (Geraci et al., 1976; Eaton, 
1979, Odell et al., 1980; Best, 1982).
    Several sources have published lists of mass stranding events of 
cetaceans during attempts to identify relationships between those 
stranding events and military sonar (Hildebrand, 2004; IWC, 2005; 
Taylor et al., 2004). For example, based on a review of stranding 
records between 1960 and 1995, the International Whaling Commission 
(IWC, 2005) identified 10 mass stranding events of Cuvier's beaked 
whales that had been reported and one mass stranding of four Baird's 
beaked whales (Berardius bairdii). The IWC concluded that, out of eight 
stranding events reported from the mid-1980s to the summer of 2003, 
seven had been associated with the use of mid-frequency sonar, one of 
those seven had been associated with the use of low frequency sonar, 
and the remaining stranding event had been associated with the use of 
seismic airguns. None of the strandings has been associated with high 
frequency sonar such as the Q-20 sonar proposed to be tested in this 
action. Therefore, NMFS does not consider it likely that the proposed 
Q-20 testing activity would cause marine mammals to strand.

Effects on Marine Mammal Habitat

    There are no areas within the NSWC PCD that are specifically 
considered as important physical habitat for marine mammals.
    The prey of marine mammals are considered part of their habitat. 
The Navy's Final Environmental Impact Statement and Overseas 
Environmental Impact Statement (FEIS) on the research, development, 
test and evaluation activities in the NSWC PCD study area contains a 
detailed discussion of the potential effects to fish from HFAS/MFAS. 
These effects are the same as expected from the proposed Q-20 sonar 
testing activities within the same area.
    The extent of data, and particularly scientifically peer-reviewed 
data, on the effects of high intensity sounds on fish is limited. In 
considering the available literature, the vast majority of fish species 
studied to date are hearing generalists and cannot hear sounds above 
500 to 1,500 Hz (depending upon the species), and, therefore, 
behavioral effects on these species from higher frequency sounds are 
not likely. Moreover, even those fish species that may hear above 1.5 
kHz, such as a few sciaenids and the clupeids (and relatives), have 
relatively poor hearing above 1.5 kHz as compared to their hearing 
sensitivity at lower frequencies. Therefore, even among the species 
that have hearing ranges that overlap with some mid- and high frequency 
sounds, it is likely that the fish will only actually hear the sounds 
if the fish and source are very close to one another. Finally, since 
the vast majority of sounds that are of biological relevance to fish 
are below 1 kHz (e.g., Zelick et al., 1999; Ladich and Popper, 2004), 
even if a fish detects a mid-or high frequency sound, these sounds will 
not mask detection of lower frequency biologically relevant sounds. 
Based on the above information, there will likely be few, if any, 
behavioral impacts on fish.
    Alternatively, it is possible that very intense mid- and high 
frequency signals could have a physical impact on fish, resulting in 
damage to the swim bladder and other organ systems. However, even these 
kinds of effects have only been shown in a few cases in response to 
explosives, and only when the fish has been very close to the source. 
Such effects have never been indicated in response to any Navy sonar. 
Moreover, at greater distances (the distance clearly would depend on 
the intensity of the signal from the source) there appears to be little 
or no impact on fish, and particularly no impact on fish that do not 
have a swim bladder or other air bubble that would be affected by rapid 
pressure changes.

Mitigation Measures

    In order to issue an incidental take authorization (ITA) under 
Section 101(a)(5)(D) of the MMPA, NMFS must set forth the ``permissible 
methods of taking pursuant to such activity, and other means of 
effecting the least practicable adverse impact on such species or stock 
and its habitat, paying particular attention to rookeries, mating 
grounds, and areas of similar significance.'' The National Defense 
Authorization Act (NDAA) of 2004 amended the MMPA as it relates to 
military-readiness activities and the ITA process such that ``least 
practicable adverse impact'' shall include consideration of personnel 
safety, practicality of implementation, and impact on the effectiveness 
of the ``military readiness activity.'' The Q-20 sonar testing 
activities described in the Navy's IHA application are considered 
military readiness activities.
    For the proposed Q-20 sonar testing activities in the GOM, NMFS 
worked with the Navy to develop mitigation measures. The following 
mitigation measures are required in the IHA issued to the Navy to take 
marine mammals incidental to its Q-20 testing activities.

Personnel Training

    Marine mammal mitigation training for those who participate in the 
active sonar activities is a key element of the protective measures. 
The goal of this training is for key personnel onboard Navy platforms 
in the Q-20 Study Area to understand the protective measures and be 
competent to carry them out. The Marine Species Awareness Training 
(MSAT) is provided to all applicable participants, where appropriate. 
The program addresses environmental protection, laws governing the 
protection of marine species, Navy stewardship, and general observation 
information including more detailed information for spotting marine 
mammals. Marine mammal observer training will be provided before active 
sonar testing begins.
    Marine observers would be aware of the specific actions to be taken 
based on the RDT&E platform if a marine mammal is observed. 
Specifically, the following requirements for personnel training would 
apply:
     All marine observers onboard platforms involved in the Q-
20 sonar test activities will review the NMFS-approved MSAT material 
prior to use of active sonar.
     Marine Observers shall be trained in marine mammal 
recognition. Marine Observer training shall include completion of the 
Marine Species Awareness Training, instruction on governing laws and 
policies, and overview of the specific Gulf of Mexico species present, 
and observer roles and responsibilities.
     Marine observers will be trained in the most effective 
means to ensure quick and effective communication within the

[[Page 49422]]

command structure in order to facilitate implementation of mitigation 
measures if marine species are spotted.

Range Operating Procedures

    The following procedures would be implemented to maximize the 
ability of Navy personnel to recognize instances when marine mammals 
are in the vicinity.
(1) Observer Responsibilities
     Marine observers will have at least one set of binoculars 
available for each person to aid in the detection of marine mammals.
     Marine observers will conduct monitoring for at least 15 
minutes prior to the initiation of and for at least 15 minutes after 
the cessation of Q-20 testing activities.
     Marine observers will scan the water from the ship to the 
horizon and be responsible for all observations in their sector. In 
searching the assigned sector, the lookout will always start at the 
forward part of the sector and search aft (toward the back). To search 
and scan, the lookout will hold the binoculars steady so the horizon is 
in the top third of the field of vision and direct the eyes just below 
the horizon. The lookout will scan for approximately five seconds in as 
many small steps as possible across the field seen through the 
binoculars. They will search the entire sector in approximately five-
degree steps, pausing between steps for approximately five seconds to 
scan the field of view. At the end of the sector search, the glasses 
will be lowered to allow the eyes to rest for a few seconds, and then 
the lookout will search back across the sector with the naked eye.
     Observers will be responsible for informing the Test 
Director of any marine mammal that may need to be avoided, as 
warranted.
     These procedures would apply as much as possible during 
RMMV operations. When an RMMV is operating over the horizon, it is 
impossible to follow and observe it during the entire path. An observer 
will be located on the support vessel or platform to observe the area 
when the system is undergoing a small track close to the support 
platform.
(2) Operating Procedures
     Test Directors will, as appropriate to the event, make use 
of marine species detection cues and information to limit interaction 
with marine species to the maximum extent possible, consistent with the 
safety of the ship.
     During Q-20 sonar activities, personnel will utilize all 
available sensor and optical system (such as Night Vision Goggles) to 
aid in the detection of marine mammals.
     Navy aircraft participating will conduct and maintain, 
when operationally feasible, required, and safe, surveillance for 
marine species of concern as long as it does not violate safety 
constraints or interfere with the accomplishment of primary operational 
duties.
     Marine mammal detections by aircraft will be immediately 
reported to the Test Director. This action will occur when it is 
reasonable to conclude that the course of the ship will likely close 
the distance between the ship and the detected marine mammal.
     Special conditions applicable for dolphins only: If, after 
conducting an initial maneuver to avoid close quarters with dolphins, 
the Test Director or the Test Director's designee concludes that 
dolphins are deliberately closing to ride the vessel's bow wave, no 
further mitigation actions are necessary while the dolphins or 
porpoises continue to exhibit bow wave riding behavior.
     Sonar levels (generally)--Navy will operate sonar at the 
lowest practicable level, except as required to meet testing 
objectives.

Clearance Procedures

    When the test platform (surface vessel or aircraft) arrives at the 
test site, an initial evaluation of environmental suitability will be 
made. This evaluation will include an assessment of sea state and 
verification that the area is clear of visually detectable marine 
mammals and indicators of their presence. For example, large flocks of 
birds and large schools of fish are considered indicators of potential 
marine mammal presence.
    If the initial evaluation indicates that the area is clear, visual 
surveying will begin. The area will be visually surveyed for the 
presence of protected species and protected species indicators. Visual 
surveys will be conducted from the test platform before test activities 
begin. When the platform is a surface vessel, no additional aerial 
surveys will be required. For surveys requiring only surface vessels, 
aerial surveys may be opportunistically conducted by aircraft 
participating in the test.
    Shipboard monitoring will be staged from the highest point possible 
on the vessel. The observer(s) will be experienced in shipboard 
surveys, familiar with the marine life of the area, and equipped with 
binoculars of sufficient magnification. Each observer will be provided 
with a two-way radio that will be dedicated to the survey, and will 
have direct radio contact with the Test Director. Observers will report 
to the Test Director any sightings of marine mammals or indicators of 
these species, as described previously. Distance and bearing will be 
provided when available. Observers may recommend a ``Go''/``No Go'' 
decision, but the final decision will be the responsibility of the Test 
Director.
    Post-mission surveys will be conducted from the surface vessel(s) 
and aircraft used for pre-test surveys. Any affected marine species 
will be documented and reported to NMFS. The report will include the 
date, time, location, test activities, species (to the lowest taxonomic 
level possible), behavior, and number of animals.
    NMFS has carefully evaluated the Navy's proposed mitigation 
measures and considered a range of other measures in the context of 
ensuring that NMFS prescribes the means of effecting the least 
practicable adverse impact on the affected marine mammal species and 
stocks and their habitat. Our evaluation of potential measures included 
consideration of the following factors in relation to one another:
     The manner in which, and the degree to which, the 
successful implementation of the measure is expected to minimize 
adverse impacts to marine mammals;
     The proven or likely efficacy of the specific measure to 
minimize adverse impacts as planned; and
     The practicability of the measure for applicant 
implementation, including consideration of personnel safety, 
practicality of implementation, and impact on the effectiveness of the 
military readiness activity.
    Based on careful evaluation and assessing these measures, we have 
determined that the mitigation measures listed above provide the means 
of effecting the least practicable adverse impacts on marine mammals 
species or stocks and their habitat, paying particular attention to 
rookeries, mating grounds, and areas of similar significance, while 
also considering personnel safety, practicality of implementation, and 
impact on the effectiveness of the military readiness activity.

Monitoring Measures

    In order to issue an ITA for an activity, section 101(a)(5)(D) of 
the MMPA states that NMFS must set forth ``requirements pertaining to 
the monitoring and reporting of such taking.'' The MMPA implementing 
regulations at 50 CFR 216.104(a)(13) indicate that requests for LOAs 
must include the suggested means of accomplishing the necessary 
monitoring and reporting that will result in

[[Page 49423]]

increased knowledge of the species and of the level of taking or 
impacts on populations of marine mammals that are expected to be 
present.
    The RDT&E Monitoring Program, proposed by the Navy as part of its 
IHA application, is focused on mitigation-based monitoring. Main 
monitoring techniques include use of civilian personnel as marine 
mammal observers during pre-, during, and post-, test events.
    Systematic monitoring of the affected area for marine mammals will 
be conducted prior to, during, and after test events using aerial and/
or ship-based visual surveys. Observers will record information during 
the test activity. Data recorded will include exercise information 
(time, date, and location) and marine mammal and/or indicator presence, 
species, number of animals, their behavior, and whether there are 
changes in the behavior. Personnel will immediately report observed 
stranded or injured marine mammals to NMFS stranding response network 
and NMFS Regional Office. Reporting requirements are included in the 
Naval Surface Warfare Center Panama City Division (NSWC PCD) Mission 
Activities Final Environmental Impact Statement/Overseas Environmental 
Impact Statement Annual Activity report as required by its Final Rule 
(DON, 2009; NMFS, 2010d).

Ongoing Monitoring

    The Navy has an existing Monitoring Plan that provides for site-
specific monitoring for MMPA and Endangered Species Act (ESA) listed 
species, primarily marine mammals within the Gulf of Mexico, including 
marine water areas of the Q-20 Study Area (DON, 2009; NMFS, 2010d). 
This monitoring plan was initially developed in support of the NSWC PCD 
Mission Activities Final Environmental Impact Statement/Overseas 
Environmental Impact Statement and subsequent Final Rule by NMFS (DON, 
2009; NMFS, 2010d). The primary goals of monitoring are to evaluate 
trends in marine species distribution and abundance in order to assess 
potential population effects from Navy training and testing events and 
determine the effectiveness of the Navy's mitigation measures. The 
monitoring plan, adjusted annually in consultation with NMFS, includes 
aerial- and ship-based visual observations, acoustic monitoring, and 
other efforts such as oceanographic observations.

Estimated Take by Incidental Harassment

    As mentioned previously, with respect to military readiness 
activities, Section 3(18)(B) of the MMPA defines ``harassment'' as: (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].
    A thorough analysis of the types of Level A and B harassments and 
the acoustic take criteria are provided in the Federal Register notice 
for the proposed IHA (77 FR 12010; February 28, 2012), and is not 
repeated here. Although analyses earlier in the document show that 
there are 22 species of marine mammals are found present in the 
vicinity of the proposed Q-20 testing area, due to the low density of 
many species and the small zones of influence resulted from the 
proposed sonar testing, only six species may be exposed to noise levels 
that constitute a ``take''. Based on the analysis and acoustical 
modeling, which can be found in Appendix A Supplemental Information for 
Underwater Noise Analysis of the Navy's IHA application, NSWC PCD's Q-
20 sonar operations in non-territorial waters may expose up to six 
species to sound likely to result in Level B (behavioral) harassment 
(Table 1). They include the bottlenose dolphin (Tursiops truncatus), 
Atlantic spotted dolphin (Stenella frontalis), pantropical spotted 
dolphin (Stenella attenuata), striped dolphin (Stenella coeruleoalba), 
spinner dolphin (Stenella longirostris), and Clymene dolphin (Stenella 
clymene). No marine mammals would be exposed to levels of sound likely 
to result in TTS. The Navy requested that the take numbers of marine 
mammals for its IHA reflect the exposure numbers listed in Table 1.

           Table 1--Estimates of Marine Mammal Exposures From Sonar in Non-Territorial Waters per Year
----------------------------------------------------------------------------------------------------------------
                                                                                                      Level B
                      Marine mammal species                           Level A      Level B (TTS)   (behavioral)
----------------------------------------------------------------------------------------------------------------
Bottlenose dolphin (GOM oceanic)................................               0               0             399
Pantropical spotted dolphin.....................................               0               0             126
Atlantic spotted dolphin........................................               0               0             315
Spinner dolphin.................................................               0               0             126
Clymene dolphin.................................................               0               0              42
Striped dolphin.................................................               0               0              42
----------------------------------------------------------------------------------------------------------------

Negligible Impact and Small Numbers Analysis and Determination

    Pursuant to NMFS' regulations implementing the MMPA, an applicant 
is required to estimate the number of animals that will be ``taken'' by 
the specified activities (i.e., takes by harassment only, or takes by 
harassment, injury, and/or death). This estimate informs the analysis 
that NMFS must perform to determine whether the activity will have a 
``negligible impact'' on the species or stock. Level B (behavioral) 
harassment occurs at the level of the individual(s) and does not assume 
any resulting population-level consequences, though there are known 
avenues through which behavioral disturbance of individuals can result 
in population-level effects. A negligible impact finding is based on 
the lack of likely adverse effects on annual rates of recruitment or 
survival (i.e., population-level effects). An estimate of the number of 
Level B harassment takes, alone, is not enough information on which to 
base an impact determination. In addition to considering estimates of 
the number of marine mammals that might be ``taken'' through behavioral 
harassment, NMFS must consider other factors, such as the likely nature 
of any responses (their intensity, duration, etc.), the context of any 
responses (critical reproductive time or location, migration, etc.), or 
any of the other variables mentioned in the first paragraph (if known), 
as well as the number and nature of estimated Level A takes, the number 
of estimated mortalities, and effects on habitat.

[[Page 49424]]

    The Navy's specified activities have been described based on best 
estimates of the number of Q-20 sonar test hours that the Navy will 
conduct. Taking the above into account, considering the sections 
discussed below, and dependent upon the implementation of the 
mitigation measures, NMFS has determined that Navy's Q-20 sonar test 
activities in the non-territorial waters will have a negligible impact 
on the marine mammal species and stocks present in the Q-20 Study Area.

Behavioral Harassment

    As discussed in the Potential Effects of Exposure of Marine Mammals 
to Sonar section and illustrated in the conceptual framework, marine 
mammals can respond to HFAS/MFAS in many different ways, a subset of 
which qualifies as harassment. One thing that the take estimates do not 
take into account is the fact that most marine mammals will likely 
avoid strong sound sources to one extent or another. Although an animal 
that avoids the sound source will likely still be taken in some 
instances (such as if the avoidance results in a missed opportunity to 
feed, interruption of reproductive behaviors, etc.), in other cases 
avoidance may result in fewer instances of take than were estimated or 
in the takes resulting from exposure to a lower received level than was 
estimated, which could result in a less severe response. The Navy 
proposes only 420 hours of high-frequency sonar operations per year for 
the Q-20 sonar testing activities, spread among 42 days with an average 
of 10 hours per day, in the Q-20 Study Area. There will be no powerful 
tactical mid-frequency sonar involved. Therefore, there will be no 
disturbance to marine mammals resulting from MFAS systems (such as 
53C). The effects that might be expected from the Navy's major training 
exercises at the Atlantic Fleet Active Sonar Training (AFAST) Range, 
Hawaii Range Complex (HRC), and Southern California (SOCAL) Range 
Complex will not occur here. The source level of the Q-20 sonar is much 
lower than the 53C series MFAS system, and high frequency signals tend 
to have more attenuation in the water column and are more prone to lose 
their energy during propagation. Therefore, their zones of influence 
are much smaller, thereby making it easier to detect marine mammals and 
prevent adverse effects from occurring.
    The Navy has been conducting monitoring activities since 2006 on 
its sonar operations in a variety of the Naval range complexes (e.g., 
AFAST, HRC, SOCAL) under the Navy's own protective measures and under 
the regulations and LOAs. Monitoring reports based on these major 
training exercises using military sonar have shown that no marine 
mammal injury or mortality has occurred as a result of the sonar 
operations (DoN, 2011a; 2011b).

Diel Cycle

    As noted previously, many animals perform vital functions, such as 
feeding, resting, traveling, and socializing on a diel cycle (24-hr 
cycle). Substantive behavioral reactions to noise exposure (such as 
disruption of critical life functions, displacement, or avoidance of 
important habitat) are more likely to be significant if they last more 
than one diel cycle or recur on subsequent days (Southall et al., 
2007). Consequently, a behavioral response lasting less than one day 
and not recurring on subsequent days is not considered particularly 
severe unless it could directly affect reproduction or survival 
(Southall et al., 2007).
    In the previous section, we discussed the fact that potential 
behavioral responses to HFAS/MFAS that fall into the category of 
harassment could range in severity. By definition, the takes by 
behavioral harassment involve the disturbance of a marine mammal or 
marine mammal stock in the wild by causing disruption of natural 
behavioral patterns (such as migration, surfacing, nursing, breeding, 
feeding, or sheltering) to a point where such behavioral patterns are 
abandoned or significantly altered. In addition, the amount of time the 
Q-20 sonar testing will occur is 420 hours per year in non-territorial 
waters, and is spread among 42 days with an average of 10 hours per 
day. Thus the exposure is expected to be sporadic throughout the year 
and is localized within a specific testing site.

TTS

    Based on the Navy's model and NMFS analysis, it is unlikely that 
marine mammals would be exposed to sonar received levels that could 
cause TTS due to the lower source level (207-212 dB re 1 [micro]Pa at 1 
m) and high attenuation rate of the HFAS signals (above 35 kHz).

Acoustic Masking or Communication Impairment

    As discussed above, it is possible that anthropogenic sound could 
result in masking of marine mammal communication and navigation 
signals. However, masking only occurs during the time of the signal 
(and potential secondary arrivals of indirect rays), versus TTS, which 
occurs continuously for its duration. The Q-20 ping duration is in 
milliseconds and the system is relatively low-powered making its range 
of effect smaller. Therefore, masking effects from the Q-20 sonar 
signals are expected to be minimal. If masking or communication 
impairment were to occur briefly, it would be in the frequency range of 
above 35 kHz (the lower limit of the Q-20 signals), which overlaps with 
some marine mammal vocalizations; however, it would likely not mask the 
entirety of any particular vocalization or communication series because 
the pulse length, frequency, and duty cycle of the Q-20 sonar signal 
does not perfectly mimic the characteristics of any marine mammal's 
vocalizations.

PTS, Injury, or Mortality

    Based on the Navy's model and NMFS analysis, it is unlikely that 
PTS, injury, or mortality of marine mammals would occur from the 
proposed Q-20 sonar testing activities. As discussed earlier, the lower 
source level (207-212 dB re 1 [micro]Pa at 1 m) and high attenuation 
rate of the HFAS signals (above 35 kHz) make it highly unlikely that 
any marine mammals in the vicinity would be injured (including PTS) or 
killed as a result of sonar exposure.
    Based on the aforementioned assessment, NMFS determines that 
approximately 399 bottlenose dolphins, 126 pantropical spotted 
dolphins, 315 Atlantic spotted dolphins, 126 spinner dolphins, 42 
Clymene dolphins, and 42 striped dolphins would be affected by Level B 
behavioral harassment as a result of the proposed Q-20 sonar testing 
activities. These numbers represent approximately 10.76%, 0.37%, 1.26%, 
6.33%, and 0.64% of bottlenose dolphins (GOM oceanic stock), 
pantropical spotted dolphins, striped dolphins, spinner dolphins, and 
Clymene dolphins, respectively, of these species in the GOM region 
(calculation based on NMFS 2011 US Atlantic and Gulf of Mexico Marine 
Mammal Stock Assessment). The percentage of potentially affected 
Atlantic spotted dolphin is unknown since there is no current 
population assessment of this species in the Gulf of Mexico region. 
However, based on the most recent abundance estimate published in NMFS 
Atlantic and GOM SARs conducted in the northern Gulf of Mexico outer 
continental shelf during fall 2000-2001 and oceanic waters during 
spring/summer 2003-2004, the population was estimated at 37,611 (NMFS 
2011). Using this number, it is estimated that approximately 0.84% of 
Atlantic spotted dolphins would be taken by Level B behavioral 
harassment from the Navy's proposed sonar test activities.
    The supporting analyses suggest that no marine mammals will be 
killed, injured, or receive TTS as a result of the

[[Page 49425]]

Q-20 sonar testing activities, and no more than a small number of any 
affected species will be taken in the form of short-term Level B 
behavioral harassment. In addition, since these impacts will likely not 
occur in areas and times critical to reproduction, NMFS has determined 
that the taking of these species as a result of the Navy's Q-20 sonar 
test will have a negligible impact on the marine mammal species and 
stocks present in the Q-20 Study Area.

Subsistence Harvest of Marine Mammals

    NMFS has determined that the total taking of marine mammal species 
or stocks from the Navy's Q-20 sonar testing in the Q-20 Study Area 
would not have an unmitigable adverse impact on the availability of the 
affected species or stocks for subsistence uses, since there are no 
such uses in the specified area.

Endangered Species Act (ESA)

    Based on the analysis of the Navy Marine Resources Assessment (MRA) 
data on marine mammal distributions, there is near zero probability 
that sperm whale will occur in the vicinity of the Q-20 test area. No 
other ESA-listed marine mammal is expected to occur in the vicinity of 
the test area. In addition, acoustic modeling analysis indicates the 
ESA-listed sperm whale would not be exposed to levels of sound 
constituting a ``take'' under the MMPA, due to the low source level and 
high attenuation rates of the Q-20 sonar signal. Therefore, NMFS has 
determined that ESA-listed species will not be affected as the result 
of the Navy's Q-20 testing activities.

National Environmental Policy Act (NEPA)

    In 2009, the Navy prepared a Final Environmental Impact Statement/
Overseas Environmental Impact Statement for the NSWC PCD Mission 
Activities (FEIS/OEIS), and NMFS subsequently adopted the FEIS/OEIS for 
its rule governing the Navy's RDT&E activities in the NSWC PCD Study 
Area. The currently proposed Q-20 sonar testing activities are similar 
to the sonar testing activities described in the FEIS/OEIS for NSWC PCD 
mission activities. NMFS prepared an Environmental Assessment analyzing 
the potential impacts of the additional Q-20 sonar test activities and 
reached a finding of no significant impact.

    Dated: July 26, 2012.
Helen M. Golde,
Acting Director, Office of Protected Resources, National Marine 
Fisheries Service.
[FR Doc. 2012-20167 Filed 8-15-12; 8:45 am]
BILLING CODE 3510-22-P