Taking and Importing Marine Mammals; Taking Marine Mammals Incidental to the U.S. Navy Operations of Surveillance Towed Array Sensor System Low Frequency Active Sonar, 37404-37418 [07-3329]

Agencies

• DEPARTMENT OF COMMERCE
• National Oceanic and Atmospheric Administration

[Federal Register Volume 72, Number 130 (Monday, July 9, 2007)]
[Proposed Rules]
[Pages 37404-37418]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 07-3329]



[[Page 37403]]

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Part V





Department of Commerce





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National Oceanic and Atmospheric Administration



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50 CFR Part 216



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

Federal Register / Vol. 72, No. 130 / Monday, July 9, 2007 / Proposed 
Rules

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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

50 CFR Part 216

[Docket No. 070703226-7226-01; I.D. 062206A]
RIN 0648-AT80


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

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

ACTION:  Proposed rule; request for comments.

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SUMMARY:  NMFS has received a request from the U.S. Navy for an 
authorization under the Marine Mammal Protection Act (MMPA) to take 
marine mammals, by harassment, incidental to conducting operations of 
Surveillance Towed Array Sensor System (SURTASS) Low Frequency Active 
(LFA) sonar from August 16, 2007, through August 15, 2012. By this 
document, NMFS is proposing regulations to govern that take. In order 
to issue Letters of Authorization (LOAs) and final regulations 
governing the take, NMFS must determine that the taking will have a 
negligible impact on the affected species or stocks of marine mammals. 
NMFS regulations must set forth the permissible methods of take and 
other means of effecting the least practicable adverse impact on the 
affected species or stocks of marine mammals and their habitat. NMFS 
invites comment on the proposed regulations and findings.

DATES: Comments and information must be received by July 24, 2007.

ADDRESSES:  You may submit comments on the application and proposed 
rule, using the identifier 062206A, by any of the following methods:
     E-mail: PR1.062306A@noaa.gov.
     Federal e-Rulemaking Portal: https://www.regulations.gov.
     Hand-delivery or mailing of paper, disk, or CD-ROM 
comments should be addressed to: P. Michael Payne, Chief, Permits, 
Conservation and Education Division, Office of Protected Resources, 
National Marine Fisheries Service, 1315 East-West Highway, Silver 
Spring, MD 20910-3225.
    A copy of the application, containing a list of references used in 
this document, and other documents cited herein, may be obtained by 
writing to the above address, by telephoning one of the contacts listed 
under FOR FURTHER INFORMATION CONTACT, or at: https://www.nmfs.noaa.gov/
pr/permits/incidental.htm.
    A copy of the Navy's Final Supplemental Environmental Impact 
Statement (Final SEIS) and the Final Environmental Impact Statement 
(Final EIS) can be downloaded at: https://www.surtass-lfa-eis.com. 
Documents cited in this proposed rule may also be viewed, by 
appointment, during regular business hours at this address.

FOR FURTHER INFORMATION CONTACT:  Kenneth Hollingshead, NMFS, at 301-
713-2289, ext 128.

SUPPLEMENTARY INFORMATION:

Background

    Section 101(a)(5)(A) of the Marine Mammal Protection Act (16 U.S.C. 
1361 et seq.) (MMPA) directs the Secretary of Commerce (Secretary) to 
allow, upon request, the incidental, but not intentional taking of 
marine mammals by U.S. citizens who engage in a military readiness 
activity if certain findings are made and regulations are issued.
    An authorization may be granted for periods of 5 years or less if 
the Secretary finds that the total taking will have a negligible impact 
on the affected species or stock(s), will not have an unmitigable 
adverse impact on the availability of the species or stock(s) for 
certain subsistence uses. The Secretary must also issue regulations 
setting forth the permissible methods of taking and other means of 
effecting the least practicable adverse impact, including a 
consideration of personnel safety, the practicality of implementation 
of any mitigation, and the impact on the effectiveness of the subject 
military readiness activity, and the requirements pertaining to the 
monitoring and reporting of such taking. NMFS authorizes the incidental 
take through ``letters of authorization'' (LOAs) (50 CFR 216.106)
    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.'' For the purposes of ``military readiness activities'' 
harassment is defined 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].
    The term ``military readiness activity'' is defined in Public Law 
107-314 (16 U.S.C. 703 note) to include all training and operations of 
the Armed Forces that relate to combat; and the adequate and realistic 
testing of military equipment, vehicles, weapons and sensors for proper 
operation and suitability for combat use. The term expressly does not 
include the routine operation of installation operating support 
functions, such as military offices, military exchanges, commissaries, 
water treatment facilities, storage facilities, schools, housing, motor 
pools, laundries, morale, welfare and recreation activities, shops, and 
mess halls; the operation of industrial activities; or the construction 
or demolition of facilities used for a military readiness activity.

Summary of Request

    On May 12, 2006, NMFS received an application from the U.S. Navy 
requesting an authorization under section 101(a)(5)(A) of the MMPA for 
the taking of marine mammals incidental to deploying the SURTASS LFA 
sonar system for military readiness activities to include training, 
testing and routine military operations within the world's oceans 
(except for Arctic and Antarctic waters, coastal regions as specified 
in this proposed rule, and offshore biologically important areas 
(OBIAs)) for a period of time not to exceed 5 years. According to the 
Navy application, SURTASS LFA sonar would operate a maximum of 4 ship 
systems in areas of the Pacific, Atlantic, and Indian oceans and the 
Mediterranean Sea in which SURTASS LFA sonar could potentially operate.
    The purpose of SURTASS LFA sonar is to provide the Navy with a 
reliable and dependable system for long-range detection of quieter, 
harder-to-find submarines. Low-frequency (LF) sound travels in seawater 
for greater distances than higher frequency sound used by most other 
active sonars. According to the Navy, the SURTASS LFA sonar system 
would meet the Navy's need for improved detection and tracking of new-
generation submarines at a longer range. This would maximize the 
opportunity for U.S. armed forces to safely react to, and defend 
against, potential submarine threats while remaining a safe distance 
beyond a submarine's effective weapons range.
    NMFS and the Navy have determined that the Navy's SURTASS LFA sonar

[[Page 37405]]

testing and training operations constitute a military readiness 
activity because those activities constitute ``training and operations 
of the Armed Forces that relate to combat'' and constitute ``adequate 
and realistic testing of military equipment, vehicles, weapons and 
sensors for proper operation and suitability for combat use.''
    NMFS' current regulations governing takings incidental to SURTASS 
LFA sonar activities and the current LOA expire on August 16, 2007.
    On September 28, 2006 (71 FR 56965), NMFS published a Notice of 
Receipt of Application on the U.S. Navy application and invited 
interested persons to submit comments, information, and suggestions 
concerning the application and the structure and contents of 
regulations. These comments were considered in the development of this 
proposed rule.

Prior Litigation, Involving LFA Sonar

    On August 7, 2002, the Natural Resources Defense Council, the U.S. 
Humane Society and four other plaintiffs filed suit against the Navy 
and NMFS over SURTASS LFA sonar use and permitting. The U.S. District 
Court for the Northern District of California (Court) issued its 
Opinion and Order on the parties' motions for summary judgment in the 
SURTASS LFA litigation on August 26, 2003. The Court found deficiencies 
in Navy and NMFS compliance with the MMPA, Endangered Species Act 
(ESA), and National Environmental Policy Act (NEPA). The Court 
determined that an injunction was warranted but did not order a 
complete ban on the use of SURTASS LFA sonar. Specifically, the Court 
found that a total ban on the employment of SURTASS LFA would interfere 
with the Navy's ability to ensure military readiness and to protect 
those serving in the military against the threat posed by hostile 
submarines. The Court directed the parties to meet and confer on the 
scope of a tailored permanent injunction, which would allow for 
continued operation of the system with additional mitigation measures. 
This mediation session occurred on September 25, 2003 in San Francisco. 
On October 14, 2003, the Court issued a Stipulation Regarding Permanent 
Injunction for the operations of SURTASS LFA sonar from both R/V Cory 
Chouest and USNS IMPECCABLE (T-AGOS 23) in stipulated portions of the 
Northwest Pacific/Philippine Sea, Sea of Japan, East China Sea, and 
South China Sea with certain year-round and seasonal restrictions. On 
July 7, 2005, the Court amended the injunction at Navy's request to 
expand the potential areas of operation based on real-world 
contingencies. The Navy's Final SEIS was prepared in response to the 
Court's ruling on the motion for preliminary injunction, addressing the 
concerns identified by the Court, to provide additional information 
regarding the environment that could potentially be affected by the 
SURTASS LFA sonar systems, and to provide additional information 
related to mitigation.
    A detailed description of the operations is contained in the Navy's 
application (DON, 2006) and the Final SEIS (DON, 2007) which are 
available upon request (see ADDRESSES).

Description of the Activity

    The SURTASS LFA sonar system is a long-range, LF sonar (between 100 
and 500 Hertz (Hz)) that has both active and passive components. It 
does not have to rely on detection of noise generated by the target. 
The active component of the system is a set of up to 18 LF acoustic 
transmitting source elements (called projectors) suspended from a cable 
underneath a ship. The projectors are devices that transform electrical 
energy to mechanical energy by setting up vibrations, or pressure 
disturbances, with the water to produce the pulse or ping. The SURTASS 
LFA sonar acoustic transmission is an omnidirectional (full 360 
degrees) beam in the horizontal. A narrow vertical beamwidth can be 
steered above or below the horizontal. The source level (SL) of an 
individual projector in the SURTASS LFA sonar array is approximately 
215 decibels (dB), and because of the physics involved in beam forming 
and transmission loss processes, the array can never have a sound 
pressure level (SPL) higher than the SPL of an individual projector. 
The expected water depth at the center of the array is 400 ft (122 m) 
and the expected minimum water depth at which the SURTASS LFA vessel 
will operate is 200 m (656.2 ft).
    The typical SURTASS LFA sonar signal is not a constant tone, but 
rather a transmission of various signal types that vary in frequency 
and duration (including continuous wave (CW) and frequency-modulated 
(FM) signals). A complete sequence of sound transmissions is referred 
to by the Navy as a ``ping'' and can last as short as 6 seconds (sec) 
to as long as 100 sec, normally with no more than 10 sec at any single 
frequency. The time between pings is typically from 6 to 15 minutes. 
Average duty cycle (ratio of sound ``on'' time to total time) is less 
than 20 percent; however, the duty cycle, based on historical operating 
parameters, is normally 7.5 percent.
    The passive, or listening, component of the system is SURTASS, 
which detects returning echoes from submerged objects, such as 
submarines, through the use of hydrophones. The hydrophones are mounted 
on a horizontal array that is towed behind the ship. The SURTASS LFA 
sonar ship maintains a minimum speed of 3.0 knots (5.6 km/hr; 3.4 mi/
hr) in order to keep the array deployed.
    Because of uncertainties in the world's political climate, a 
detailed account of future operating locations and conditions cannot be 
predicted. However, for analytical purposes, a nominal annual 
deployment schedule and operational concept have been developed, based 
on current LFA operations since January 2003 and projected Fleet 
requirements. The Navy anticipates that a normal SURTASS LFA sonar 
deployment schedule for a single vessel would involve about 294 days/
year at sea. A normal at-sea mission would occur over a 49-day period, 
with 40 days of operations and 9 days transit. Based on a 7.5-percent 
duty cycle, the system would actually be transmitting for a maximum of 
72 hours per 49-day mission and 432 hours per year for each SURTASS LFA 
sonar system in operation. (In actuality however, the combined number 
of transmission hours for LFA sonar did not exceed 174 hours between 
August 16, 2002, and August 15, 2006 (Table 4 in the Navy's 
Comprehensive Report)).
    Annually, each vessel will be expected to spend approximately 54 
days in transit and 240 days performing active operations. Between 
missions, an estimated 71 days will be spent in port for upkeep and 
repair. The nominal SURTASS LFA Sonar annual and 49-day deployment 
schedule for a single ship can be seen in Table 2-1 of the Final SEIS.
    The two existing operational LFA systems are installed on two 
SURTASS vessels: R/V Cory Chouest and USNS IMPECCABLE (T-AGOS 23). To 
meet future undersea warfare requirements, the Navy is working to 
develop and introduce a compact active system deployable from existing, 
smaller SURTASS Swath-P ships. This smaller system is known as Compact 
LFA, or CLFA. CLFA consists of smaller, lighter-weight source elements 
than the current LFA system, and will be compact enough to be installed 
on the existing SURTASS platforms, VICTORIOUS Class (T-AGOS 19) 
vessels. The Navy indicates that the operational characteristics of the 
compact system are comparable to the existing LFA

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systems as presented in Subchapter 2.1 of the Final EIS and Final SEIS. 
Consequently, the potential impacts from CLFA will be similar to the 
effects from the existing SURTASS LFA systems. Three additional CLFA 
systems are planned for installation on T-AGOS 20, 21, and 22. With the 
R/V Cory Chouest retiring in FY 2008, the Navy estimates that there 
will be two systems in FY 2008 and FY 2009, 3 in FY 2010 and 4 systems 
in FY 2011 and FY 20012. At no point are there expected to be more than 
four systems in use, and thus this proposed rule analyzes the impacts 
on marine mammals due to the deployment of up to three LFA sonar 
systems through FY 2010 and four systems in FY 2011 and FY 2012.
    The SURTASS LFA sonar vessel will operate independently of, or in 
conjunction with, other naval air, surface or submarine assets. The 
vessel will generally travel in straight lines or racetrack patterns 
depending on the operational scenario.

Description of Acoustic Propagation

    The following is a very basic and generic description of the 
propagation of LFA sonar signals in the ocean and is provided to 
facilitate understanding of this action. However, because the actual 
physics governing the propagation of SURTASS LFA sound signals is 
extremely complex and dependent on numerous in-situ environmental 
factors, the following is for illustrative purposes only.
    In actual SURTASS LFA sonar operations, the crew of the SURTASS LFA 
sonar platform will measure oceanic conditions (such as sea water 
temperature and salinity versus depth) prior to and during 
transmissions and at least every 12 hours, but more frequently when 
meteorological or oceanographic conditions change. These technicians 
will then use U.S. Navy sonar propagation models to predict and/or 
update sound propagation characteristics. The short time periods 
between actual environmental observations and the subsequent model runs 
further enhance the accuracy of these predictions. Fundamentally, these 
models are used to determine what path the LF signal will take as it 
travels through the ocean and how strong the sound signal will be at 
given ranges along a particular transmission path.
    Accurately determining the speed at which sound travels through the 
water is critical to predicting the path that sound will take. The 
speed of sound in seawater varies directly with depth, temperature, and 
salinity. Thus, an increase in depth or temperature or, to a lesser 
degree, salinity, will increase the speed of sound in seawater. 
However, the oceans are not homogeneous, and the contribution of each 
of these individual factors is extremely complex and interrelated. The 
physical characteristics that determine sound speed change with depth, 
and in the case of temperature and salinity, season, geographic 
location, and locally, with time of day. After accurately measuring 
these factors, mathematical formulas or models can be used to generate 
a plot of sound speed versus water depth. This type of plot is 
generally referred to as a sound speed profile (SSP).
    Near the surface (variable within the top 1000 ft (305 m)), ocean 
near-surface water mixing results in a fairly constant temperature and 
salinity. Below the mixed layer, sea temperature drops rapidly in an 
area referred to as the thermocline. In this region, temperature 
influences the SSP, and speed decreases with depth because of the large 
decrease in temperature (sound speed decreases with decreasing 
temperature). Finally, beneath the thermocline, the temperature becomes 
fairly uniform and increasing pressure causes the SSP to increase with 
depth.
    One way to envision sound traveling though the sea is to think of 
the sound as ``rays.'' As these rays travel though the sea, their 
direction of travel changes as a result of speed changes, bending, or 
refracting, toward areas of lower speed and away from areas of higher 
speed. Depending on environmental conditions, refraction can either be 
toward or away from the surface. Additionally, the rays can be 
reflected or absorbed when they encounter the surface or the bottom. 
For example, under certain environmental conditions, near-surface sound 
rays can repeatedly be refracted upward and reflected off the surface 
and thus become trapped in a duct.
    Some of the more prevalent acoustic propagation paths in the ocean 
include: acoustic ducting; convergence zone (CZ); bottom interaction; 
and shallow-water propagation.

Acoustic Ducting

    There are two types of acoustic ducting: surface ducts and sound 
channels.
Surface Ducts
    As previously discussed, the top layer of the ocean is normally 
well mixed and has relatively constant temperature and salinity. 
Because of the effect of depth (pressure), surface layers exhibit a 
slightly positive sound speed gradient (that is, sound speed increases 
with depth). Thus, sound transmitted within this layer is refracted 
upward toward the surface. If sufficient energy is subsequently 
reflected downward from the surface, the sound can become ``trapped'' 
by a series of repeated upward refractions and downward reflections. 
Under these conditions, a surface duct, or surface channel, is said to 
exist. Sound trapped in a surface duct can travel for relatively long 
distances with its maximum range of propagation dependent on the 
specifics of the SSP, the frequency of the sound, and the reflective 
characteristics of the surface. As a general rule, surface duct 
propagation will improve as the temperature uniformity and depth of the 
layer increase. For example, transmission is improved when cloudy, 
windy conditions create a well-mixed surface layer or in high-latitude 
midwinter conditions where the mixed layer extends to several hundred 
feet deep.
Sound Channels
    Variation of sound speed, or velocity, with depth causes sound to 
travel in curved paths. A sound channel is a region in the water column 
where sound speed first decreases with depth to a minimum value, and 
then increases. Above the depth of minimum value, sound is refracted 
downward; below the depth of minimum value, sound is refracted upward. 
Thus, much of the sound starting in the channel is trapped, and any 
sound entering the channel from outside its boundaries is also trapped. 
This mode of propagation is called sound channel propagation. This 
propagation mode experiences the least transmission loss along the 
path, thus resulting in long-range transmission.
    At low and middle latitudes, the deep sound channel axis varies 
from 1,970 to 3,940 ft (600 to 1,200 m) below the surface. It is 
deepest in the subtropics and comes to the surface in the high 
latitudes, where sound propagates in the surface layer. Because 
propagating sound waves do not interact with either the sea surface or 
seafloor, sound propagation in sound channels does not attenuate as 
rapidly as bottom- or surface-interacting paths. The most common sound 
channels used by SURTASS LFA sonar are convergence zones (CZs).

Convergence Zones

    CZs are special cases of the sound-channel effect. When the surface 
layer is narrow or when sound rays are refracted downward, regions are 
created at or near the ocean surface where sound rays are focused, 
resulting in concentrated levels of high sounds. The existence of CZs 
depends on the SSP and the depth

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of the water. Due to downward refraction at shorter ranges, sound rays 
leaving the near-surface region are refracted back to the surface 
because of the positive sound speed gradient produced by the greater 
pressure at deep ocean depths. These deep-refracted rays often become 
concentrated at or near the surface at some distance from the sound 
source through the combined effects of downward and upward refraction, 
thus causing a CZ. CZs may exist whenever the sound speed at the ocean 
bottom, or at a specific depth, exceeds the sound speed at the source 
depth. Depth excess, also called sound speed excess, is the difference 
between the bottom depth and the limiting, or critical depth.
    CZs vary in range from approximately 18 to 36 nautical miles (nm) 
(33 to 67 km), depending upon the SSP. The width of the CZ is a result 
of complex interrelationships and cannot be correlated with any 
specific factor. In practice, however, the width of the CZ is usually 
on the order of 5 to 10 percent of the range. For optimum tactical 
performance, CZ propagation of SURTASS LFA signals is desired and 
expected in deep open ocean conditions.

Bottom Interaction

    Reflections from the ocean bottom and refraction within the bottom 
can extend propagation ranges. For mid- to high-level frequency sonars 
(greater than 1,000 Hz), only minimal energy enters into the bottom; 
thus reflection is the predominant mechanism for energy return. 
However, at low frequencies, such as those used by the SURTASS LFA 
sonar source, significant sound energy can penetrate the ocean floor, 
and refraction within the seafloor, not reflection, dominates the 
energy return. Regardless of the actual transmission mode (reflection 
from the bottom or refraction within the bottom), this interaction is 
generally referred to as ``bottom-bounce'' transmission.
    Major factors affecting bottom-bounce transmission include the 
sound frequency, water depth, angle of incidence, bottom composition, 
and bottom roughness. A flat ocean bottom produces the greatest 
accuracy in estimating range and bearing in the bottom-bounce mode.
    For SURTASS LFA sonar transmissions between 100 and 500 Hz, bottom 
interaction would generally occur in areas of the ocean where depths 
are between approximately 200 m (660 ft) (average minimum water depth 
for SURTASS LFA sonar deployment) and 2,000 m (6,600 ft).

Shallow Water Propagation

    In shallow water, propagation is usually characterized by multiple 
reflection paths off the sea floor and sea surface. Thus, most of the 
water column tends to become ensonified by these overlapping reflection 
paths. As LFA signals approach the shoreline, they will be affected by 
shoaling, experiencing high transmission losses through bottom and 
surface interactions. Therefore, LFA sonar would be less effective in 
shallow, coastal waters.
    In summary, for the SURTASS LFA sonar signal in low- and mid-
latitudes, the dominant propagation paths for LFA signals are CZ and 
bottom interaction (at depths <2000 m (6,600 ft)). In high-latitudes, 
surface ducting provides the best propagation. In most open ocean 
water, CZ propagation will be most prominent. The SURTASS LFA sonar 
signals will interact with the bottom, but due to high bottom and 
surface losses, SURTASS LFA sonar signals will not penetrate coastal 
waters with appreciable signal strengths.

Affected Marine Mammal Species

    In its Final SEIS and Final EIS and application, the Navy excluded 
from incidental take consideration marine mammal species that do not 
inhabit the areas in which SURTASS LFA sonar would operate. Where data 
were not available or were insufficient for one species, comparable 
data for a related species were used. Because all species of baleen 
whales produce LF sounds, and anatomical evidence strongly suggests 
their inner ears are well adapted for LF hearing, all balaenopterid 
species are considered sensitive to LF sound and, therefore, at risk of 
harassment or injury from exposure to LF sounds. The twelve species of 
baleen whales that may be affected by SURTASS LFA sonar are blue, fin, 
minke, Bryde's, sei, humpback, North Atlantic right, North Pacific 
right, southern right, pygmy right, bowhead, and gray whales.
    The odontocetes (toothed whales) that may be affected because they 
inhabit the deeper, offshore waters where SURTASS LFA sonar might 
operate include both the pelagic (oceanic) whales and dolphins and 
those coastal species that also occur in deep water including harbor 
porpoise, spectacled porpoise, beluga, Stenella spp., Risso's dolphin, 
rough-toothed dolphin, Fraser's dolphin, northern right-whale dolphin, 
southern right whale dolphin, short-beaked common dolphin, long-beaked 
common dolphin, very long-beaked common dolphin, Lagenorhynchus spp., 
Cephalorhynchus spp., bottlenose dolphin, Dall's porpoise, melon-headed 
whale, beaked whales (Berardius spp., Hyperoodon spp., Mesoplodon spp., 
Cuvier's beaked whale, Shepard's beaked whale, Longman's beaked whale), 
killer whale, false killer whale, pygmy killer whale , sperm whale, 
dwarf and pygmy sperm whales, and short-finned and long-finned pilot 
whales.
    Potentially affected pinnipeds include hooded seal, harbor seal, 
spotted seal, ribbon seal, gray seal, elephant seal, Hawaiian monk 
seal, Mediterranean monk seal, northern fur seal, southern fur seal 
(Arctocephalus spp.), harp seal, Galapagos sea lion, Japanese sea lion, 
Steller sea lion, California sea lion, Australian sea lion, New Zealand 
sea lion, and South American sea lion.
    A description of affected marine mammal species, their biology, and 
the criteria used to determine those species that have the potential 
for being taken by incidental harassment are provided and explained in 
detail in the Navy application and Final SEIS and, although not 
repeated here, are considered part of the NMFS' administrative record 
for this action. Additional information is available at the following 
URL: https://www.nmfs.noaa.gov/pr/sars/. Please refer to these documents 
for specific information on marine mammal species.

Effects on Marine Mammals

    To understand the effects of LF noise on marine mammals, one must 
understand the fundamentals of underwater sound and how the SURTASS LFA 
sonar operates in the marine environment. This description was provided 
earlier in this document and also by the Navy in Appendix B to the 
Final EIS.
    The effects of underwater noise on marine mammals are highly 
variable, and have been categorized by Richardson et al. (1995) as 
follows: (1) The noise may be too weak to be heard at the location of 
the animal (i.e. lower than the prevailing ambient noise level, the 
hearing threshold of the animal at relevant frequencies, or both); (2) 
the noise may be audible but not strong enough to elicit any overt 
behavioral response; (3) the noise may elicit behavioral reactions of 
variable conspicuousness and variable relevance to the well-being of 
the animal; these can range from subtle effects on respiration or other 
behaviors (detectable only by statistical analysis) to active avoidance 
reactions; (4) upon repeated exposure, animals may exhibit diminishing 
responsiveness (called habituation), or disturbance effects may persist 
(most likely with sounds that are

[[Page 37408]]

highly variable in characteristics, unpredictable in occurrence, and 
associated with situations that the animal perceives as a threat); (5) 
any human-made noise that is strong enough to be heard has the 
potential to reduce (mask) the ability of marine mammals to hear 
natural sounds at similar frequencies, including calls from 
conspecifics, echolocation sounds of odontocetes, and environmental 
sounds such as surf noise; and (6) very strong sounds have the 
potential to cause temporary or permanent reduction in hearing 
sensitivity, also known as threshold shift. In terrestrial mammals, and 
presumably marine mammals, received sound levels must far exceed the 
animal's hearing threshold for there to be any temporary threshold 
shift (TTS) in its hearing ability. For transient sounds, the sound 
level necessary to cause TTS is inversely related to the duration of 
the sound. As described later in this document, received sound levels 
must be even higher for there to be risk of permanent hearing 
impairment, or permanent threshold shift (PTS). Finally, intense 
acoustic or explosive events (not relevant for this activity) may cause 
trauma to tissues associated with organs vital for hearing, sound 
production, respiration and other functions. This trauma may include 
minor to severe hemorrhage. Severe hemorrhage could lead to death.
    The original analysis of potential impacts on marine mammals from 
SURTASS LFA sonar was developed by the Navy based on the results of a 
literature review; the Navy's Low Frequency Sound Scientific Research 
Program (LFS SRP) (described later in this document); and a complex, 
comprehensive program of underwater acoustical modeling.
    To assess the potential impacts on marine mammals by the SURTASS 
LFA sonar source operating at a given site, it was necessary for the 
Navy to predict the sound field that a given marine mammal species 
could be exposed to over time. This is a multi-part process involving 
(1) the ability to measure or estimate an animal's location in space 
and time, (2) the ability to measure or estimate the three-dimensional 
sound field at these times and locations, (3) the integration of these 
two data sets into the Acoustic Integration Model (AIM) to estimate the 
total acoustic exposure for each animal in the modeled population, (4) 
beginning the post-AIM analysis, converting the resultant cumulative 
exposures for a modeled population into an estimate of the risk from a 
significant disturbance of a biologically important behavior, and (5) 
using a risk continuum to convert these estimates of behavioral risk 
into an assessment of risk in terms of the level of potential 
biological removal.
    In the post-AIM analysis, as mentioned in numbers (4) and (5) 
above, a relationship was developed for converting the resultant 
cumulative exposures for a modeled population into an estimate of the 
risk to the entire population of a significant disruption of a 
biologically important behavior and of injury. This process assessed 
risk in relation to received level (RL) and repeated exposure. The 
resultant risk continuum is based on the assumption that the threshold 
of risk is variable and occurs over a range of conditions rather than 
at a single threshold. Taken together, the LFS SRP results, the 
acoustic propagation modeling, and the risk assessment provide an 
estimate of potential environmental impacts to marine mammals. The 
results of 4 years of monitoring (2002-2006) onboard the two SURTASS 
LFA sonar vessels support the use of this methodology.
    The acoustic propagation modeling was accomplished using the Navy's 
standard acoustical performance prediction transmission loss model-
Parabolic Equation (PE) version 3.4. The results of this model are the 
primary input to the AIM. AIM was used to estimate marine mammal sound 
exposures. It integrates simulated movements (including dive patterns) 
of marine mammals, a schedule of SURTASS LFA sonar transmissions, and 
the predicted sound field for each transmission to estimate acoustic 
exposure during a hypothetical SURTASS LFA sonar operation. Description 
of the PE and AIM models, including AIM input parameters for animal 
movement, diving behavior, and marine mammal distribution, abundance, 
and density, are described in detail in the original Navy application 
and the Final EIS (see box, page 4.2-11) and are not discussed further 
in this document.
    The same analytical methodology utilized in the application for the 
first 5-year rule and LOAs was utilized to provide reasonable and 
realistic estimates of the potential effects to marine mammals specific 
to the potential mission areas as presented in the application. 
Information on how the density and stock/abundance estimates are 
derived for the selected mission sites is in the Navy's application. 
These data are derived from current, published source documentation, 
and provide general area information for each mission area with 
species-specific information on the animals that could occur in that 
area, including estimates for their stock abundance and density.
    Although this proposed rule uses the same analysis that was used 
for the 2002-2007 rule, AIM is continuously updated with new marine 
mammal biological data (behavior, distribution, abundance and density) 
whenever new information becomes available. It was recently 
independently reviewed by a panel of experts in mathematics, modeling, 
acoustics, and marine mammalogy convened by NMFS' Center for 
Independent Experts (CIE). The task of the Panel was to evaluate 
whether AIM correctly implements the models and data on which it is 
based; whether animal movements are correctly implemented; and whether 
AIM meets the Council for Regulatory Environmental Monitoring (CREM) 
guidelines. As stated in their Report on AIM, the CIE Panel agreed 
that: (1) AIM appears to be correctly implemented; (2) the animal 
movement appears to be appropriately modeled; and (3) the principles of 
credible science had been addressed during the development of AIM and 
that AIM is a useful and credible tool for developing application 
models. A copy of the CIE report is available (see ADDRESSES).
    During the analytical process in the Final EIS, the Navy developed 
31 acoustic modeling scenarios for the major ocean regions. Locations 
were selected by the Navy to represent the greatest potential effects 
for each of the three major ocean acoustic regimes where SURTASS LFA 
sonar could potentially be used. These acoustic regimes were: (1) deep-
water convergence zone propagation, (2) near surface duct propagation, 
and (3) shallow water bottom interaction propagation. These sites were 
selected to model the greatest potential for effects from the use of 
SURTASS LFA sonar incorporating the following factors: (1) closest 
plausible proximity to land (from SURTASS LFA sonar operations 
standpoint), and/or offshore biologically important areas (OBIAs) where 
biological densities are higher, particularly for animals most likely 
to be affected; (2) acoustic propagation conditions that allow minimum 
propagation loss, or transmission loss (TL) (i.e., longest acoustic 
transmission ranges); and (3) time of year selected for maximum animal 
abundance. These sites represent the upper bound of impacts (both in 
terms of possible acoustic propagation conditions, and in terms of 
marine mammal population and density) that can be expected from 
operation of the SURTASS LFA sonar system. Thus, if SURTASS LFA sonar 
operations are conducted in an area that was not acoustically modeled 
in the

[[Page 37409]]

Final EIS, the potential effects would most likely be less than those 
analyzed for the most similar site in the analyses. The assumptions of 
the Final EIS are still valid and there are no new data to contradict 
the conclusions made in the Potential Impacts on Marine Mammals 
(Chapter 4) in the Final EIS. The chapter on impacts to marine mammals 
was incorporated by reference into the Navy's Final SEIS.

LFS SRP

    The goal of the 1997-1998 LFS SRP was to demonstrate the avoidance 
reaction of sensitive marine mammal species during critical 
biologically important behavior to the low frequency underwater sound 
produced by the LFA system. Testing was conducted in three phases as 
summarized here from Clark et al. (1999).
    Phase I was conducted in September through October 1997. The 
objective of Phase I was to determine whether exposure to low frequency 
sounds elicited disturbance reactions from feeding blue and fin whales. 
The goal was to characterize how whale reactions to the sounds vary, 
depending on: (1) the received level of the sound; (2) changes in the 
received level; and (3) whether the system was operating at a 
relatively constant distance or approaching the whale. Full and reduced 
LFA source power transmissions were used. The highest received levels 
at the animals were estimated to be 148 to 155 dB. In 19 focal animal 
observations (4 blue and 15 fin whales), no overt behavioral responses 
were observed. No changes in whale distribution could be related to LFA 
sonar operations, and whale the distributions correlated with the 
distribution of food.
    Phase II was conducted in January 1998. The objectives were to 
quantify responses of migrating gray whales to low frequency sound 
signals, compare whale responses to different RLs, determine whether 
whales respond more strongly to RL, sound gradient, or distance from 
the source, and to compare whale avoidance responses to an LF source in 
the center of the migration corridor versus in the offshore portion of 
the migration corridor. A single source was used to broadcast LFA sonar 
sounds up to 200 dB. Whales showed some avoidance responses when the 
source was moored 1 mi (1.8 km) offshore, in the migration path, but 
returned to their migration path when they were a few kilometers from 
the source. When the source was moored 2 mi (3.7 km) offshore, 
responses were much less, even when the source level was increased to 
200 dB, to achieve the same RL for most whales in the middle of the 
migration corridor. Also, offshore whales did not seem to avoid the 
louder offshore source.
    Phase III was conducted from February to March 1998. The objectives 
were to assess the potential effects of LFA sonar signals on behavior, 
vocalization and movement of humpback whales off the Kona coast in 
Hawaii. The maximum exposure levels in this phase were as high as 152 
dB. Approximately half of the whales observed visually ceased their 
song during the transmissions, but many of them did so while joining a 
group of whales, which is the time that singing whales usually stop 
their songs naturally. All singers who interrupted their songs were 
observed to resume singing within tens of minutes. The analysis of one 
data set showed that whales increased their song lengths during LFA 
sonar transmissions, but a second analysis indicated that song length 
changes were more complicated and depended on the portion of the song 
that was overlapped by LFA transmissions. Overall patterns of singer 
and cow-calf abundance were the same throughout the experiments as they 
had been during several years of prior study.

Risk Analysis

    To determine the potential impacts that exposure to LF sound from 
SURTASS LFA sonar operations could have on marine mammals, biological 
risk standards were defined by the Navy with associated measurement 
parameters. Based on the MMPA, the potential for biological risk was 
defined as the probability for injury (Level A) or behavioral (Level B) 
harassment of marine mammals. In this analysis, behavioral (Level B) 
harassment is defined as a significant disturbance in a biologically 
important behavior (also referred to as a biologically significant 
response). NMFS believes that this is equivalent to the MMPA definition 
of Level B harassment for military readiness activities. The potential 
for biological risk is a function of an animal's exposure to a sound 
that would potentially cause hearing, behavioral, psychological or 
physiological effects. The measurement parameters for determining 
exposure were RLs in dB, the pulse repetition interval (time between 
pings), and the number of pings received.
    Before the biological risk standards could be applied to realistic 
SURTASS LFA sonar operational scenarios, two factors had to be 
considered by the Navy: (1) how does risk vary with repeated sound 
exposure? and (2) how does risk vary with RL? The Navy addressed these 
questions by developing a function that translates the history of 
repeated exposures (as calculated in the AIM) into an equivalent RL for 
a single exposure with a comparable risk. This dual-question method is 
similar to those adopted by previous studies of risk to human hearing 
(Richardson et al., 1995; Crocker, 1997).
    It is intuitive to assume that effects on marine mammals would be 
greater with repeated exposures than for a single ping. However, no 
published data on repeated exposures of LF sound on marine mammals 
exist. Based on discussions in Richardson et al. (1995) and consistent 
with Crocker (1997), the Navy determined that the best scientific 
information available is based on the potential for effects of repeated 
exposure on human models.
    The formula L + 5 log10(N) (where L = ping level in dB and N is the 
number of pings) defines the single ping equivalent (SPE). This formula 
is considered appropriate for assessing the risk to a marine mammal of 
a significant disturbance of a biologically important behavior from LF 
sound like SURTASS LFA sonar transmissions.

Behavioral Harassment

    For reasons explained in detail in the Final EIS (Section 4.2.5), 
the Navy interpreted the results of the LFS SRP support use of 
unlimited exposure to 119 dB during an LFA sonar mission as the lowest 
value for risk. Below this level, the risk of a biologically 
significant behavioral response from marine mammals approaches zero. It 
is important to note that risk varies with both received level and 
number of exposures.
    Because the LFS SRP did not document a biologically significant 
response at maximum RLs up to 150 dB, the Navy determined there was a 
2.5-percent risk of an animal incurring a disruption of biologically 
important behavior at a SPL of 150 dB, a 50-percent risk at 165 dB, and 
a 95-percent risk at 180 dB. For more detailed information, see Chapter 
4.2.5 of the Final EIS and Navy's Technical Report 1 (Navy, 
2001). The Navy used this risk continuum analysis as an alternative to 
an all-or-nothing use of standard thresholds for the onset of 
behavioral change or injury. NMFS has reviewed and agrees with this 
approach. The subsequent discussion of risk function emphasizes the 
advantages of using a smoothly varying model of biological risk in 
relation to sound exposure. These results are analogous to dose-
response curves that are accepted as the best practice in disciplines 
such as

[[Page 37410]]

epidemiology, toxicology, and pharmacology.

Changes in Hearing Sensitivity

    In the previous (2002-2007) rule, NMFS and the Navy based their 
estimate of take by injury or the significant potential for such take 
(Level A harassment) based on the criterion of 180 dB. NMFS continues 
to believe this is a scientifically supportable value for preventing 
auditory injury or the significant potential for such injury (Level A 
harassment) as it represents a value less than where the potential 
onset of a minor TTS in hearing might occur based on Schlundt et al. 
(2000) research (see Navy Final Comprehensive Report Tables 5 through 
8). Also, an SPL of 180 dB is considered a scientifically supportable 
level for preventing auditory injury because there is general 
scientific agreement with NMFS' position that TTS is not an injury 
(i.e., does not result in tissue damage), but is temporary impairment 
to hearing (i.e., results in an increased elevation or decreased 
sensitivity in hearing) that may last for a few minutes to a few days, 
depending upon the level and duration of exposure. In addition, there 
is no evidence that TTS would occur in marine mammals at an SPL of 180 
dB. In fact, Schlundt et al. (2000) indicates that onset TTS for at 
least some species occurs at significantly higher SPLs.
    Schlundt et al.'s (2000) measurement with bottlenose dolphins and 
belugas at 1-second signal duration implies that the TTS threshold for 
a 100-second signal would be approximately 184 dB (Table 1-4, Final 
EIS). For the 400-Hz signal, Schlundt et al. found no TTS at 193 dB, 
the highest level of exposure. Therefore, NMFS believes that 
establishing onset TTS as the upper bound of Level B harassment, but 
using 180 dB as the beginning of the zone for establishing mitigation 
measures to prevent auditory injury, is warranted by the science.
    With three levels of mitigation monitoring for detecting marine 
mammals (described later in this document), NMFS and the Navy believe 
it is unlikely that any marine mammal would be exposed to received 
levels of 180 dB before being detected and the SURTASS LFA sonar shut 
down. However, because the probability is not zero, the Navy has 
included Level A harassment in its authorization request.
    Unlike with behavioral responses, an ``injury continuum'' is not 
necessary because of the very low numbers of individual marine mammals 
that could potentially experience high received sound levels, and the 
high level of effectiveness of the monitoring and shutdown protocols. 
For this action, all marine mammals exposed to an SPL of 180 dB or 
above are considered to be injured even though, the best scientific 
data available indicate a marine mammal would need to receive an SPL 
significantly higher than 180 dB to be injured.
    When SURTASS LFA sonar transmits, there is a boundary that encloses 
a volume of water where received levels equal or exceed 180 dB, and a 
volume of water outside this boundary where received levels are below 
180 dB. In this analysis, the 180-dB SPL boundary is emphasized because 
it represents a single-ping RL that is a scientifically supportable 
estimate for the potential onset of injury. Therefore, the level of 
risk for marine mammals depends on their location in relation to 
SURTASS LFA sonar and under this proposed rule, a marine mammal would 
have to receive one ping greater than or equal to 180 dB to be 
considered to have been injured or have the potential to incur an 
injury.
    Although TTS is not considered Level A harassment, PTS is 
considered Level A harassment. The onset of PTS for marine mammals may 
be 15-20 dB above TTS levels. However, mitigation measures, such as 
mitigation zones and shutdown protocols, are proposed where there is 
the potential for a marine mammal to incur TTS so as to prevent an 
animal from incurring a PTS.

Potential for Non-Auditory Injury

    Since the release of the Final EIS, an investigation by Cudahy and 
Ellison (2002) hypothesized that the threshold for in vivo tissue 
damage (including lung damage and hemorrhaging) from LF sound can be on 
the order of 180 to 190 dB. Balance and equilibrium could be affected, 
but may not result in injury. These effects are based on studies of 
humans. Vestibular (balance and equilibrium) function was investigated 
by the Navy during the Diver's Study and the results reported in LFS 
SRP Technical Report 3. Measurable performance decrements in vestibular 
function were observed for guinea pigs using 160 dB SPL signals at lung 
resonance and 190 dB SPL signals at 500 Hz. Because guinea pigs are not 
aquatic species, like humans, they are not as robust to pressure 
changes as marine mammals and, therefore, are likely more susceptible 
to injury at lower SPLs than marine mammals.
    Presently, there is controversy among researchers over whether 
marine mammals can suffer from decompression sickness. It is theorized 
that this may be caused by diving and then surfacing too quickly, 
forcing nitrogen bubbles to form in the bloodstream and tissues. Cox et 
al. (2006) stated that gas-bubble disease, induced in supersaturated 
tissues by a behavioral response to acoustic exposure, is a plausible 
pathologic mechanism for the morbidity and mortality seen in cetaceans 
associated with sonar exposure. The authors also stated that it is 
premature to judge acoustically mediated bubble growth as a potential 
mechanism and recommended further studies to investigate the 
possibility.
    As stated in Crum and Mao (1996) and as discussed in the Final EIS 
(page 10-137) and the Final SEIS (page 4-31), researchers hypothesized 
that RLs would have to exceed 190 dB for there to be the possibility of 
non-auditory trauma due to supersaturation of gases in the blood. Such 
non-auditory traumas are not expected to occur from sound exposure 
below SPLs of 180 dB.
    In light of the high detection rate of the proposed high-frequency 
marine mammal monitoring (HF/M3) sonar, ensuring required SURTASS LFA 
sonar shutdown when any marine mammal approaches or enters the 180-dB 
isopleth from LFA sonar, the risks of these traumas to a marine mammal 
approach zero.
    Additional research published in a peer-reviewed journal 
(Ultrasound in Medicine and Biology), supports the 180-dB criterion for 
injury as being a scientifically supportable level for assessing 
potential non-auditory injury to marine mammals. Laurer et al. (2002) 
from the Department of Neurosurgery, University of Pennsylvania School 
of Medicine, exposed rats to 5 minutes of continuous high intensity, 
low frequency (underwater) sound (HI-LFS) either at 180 dB SPL re 1 
microPa at 150 Hz or 194 dB SPL re 1 microPa at 250 Hz, and found no 
overt histological damage in brains of any group. Also, blood gases, 
heart rate, and main arterial blood pressure were not significantly 
influenced by HI-LFS, suggesting that there was no pulmonary 
dysfunction due to exposure. This published paper was based on work 
performed in support of Technical Report 3 of the SURTASS LFA 
Sonar Final EIS.

Strandings

    Marine mammal strandings are not a rare occurrence in nature. The 
Cetacean Stranding Database (https://www.strandings.net) registered over 
one hundred strandings worldwide in 2004. However, mass strandings, 
particularly multi-species mass strandings, are relatively rare. 
Acoustic systems are becoming increasingly implicated in marine mammal 
strandings. In

[[Page 37411]]

particular, a number of mass strandings have been linked to mid-
frequency sonars (see, e.g. Joint Interim Report on the Bahamas Marine 
Mammal Stranding Event of 15-16 March 2000, DOC and DON, 2001). Many 
theories exist as to why noise may be a factor in marine mammal 
strandings. It is theorized that marine mammals become disoriented, or 
that the sound forces them to surface too quickly, which may cause 
symptoms similar to decompression sickness, or that they are physically 
injured by the sound pressure. The biological mechanisms for effects 
that lead to strandings must be determined through scientific research.
    There is no record of SURTASS LFA sonar ever being implicated in 
any stranding event since LFA sonar prototype systems were first 
operated in the late 1980s. Moreover, the system acoustic 
characteristics differ between LF and mid-frequency (MF) sonars: LFA 
sonars use frequencies generally below 1,000 Hz, with relatively long 
signals (pulses) on the order of 60 sec; while MF sonars use 
frequencies greater than 1,000 Hz, with relatively short signals on the 
order of 1 sec. Cox et al. (2006) provided a summary of common features 
shared by the strandings events in Greece (1996), Bahamas (2000), and 
Canary Islands (2002). These included deep water close to land (such as 
offshore canyons), presence of an acoustic waveguide (surface duct 
conditions), and periodic sequences of transient pulses (i.e., rapid 
onset and decay times) generated at depths less than 10 m (32.8 ft) by 
sound sources moving at speeds of 2.6 m/s (5.1 knots) or more during 
sonar operations (D'Spain et al., 2006). These features do not relate 
to LFA operations. First, the SURTASS LFA vessel operates with a 
horizontal line array of 1,500 m (4,921 ft) length at depths below 150 
m (492 ft) and a vertical line array (LFA sonar source) at depths 
greater than 100 m (328 ft). Second, operations are limited by 
mitigation protocols to at least 22 km (12 nm) offshore. For these 
reasons, SURTASS LFA sonar cannot be operated in deep water that is 
close to land. Also, the LFA sonar signal is transmitted at depths well 
below 10 m (32.8 ft), and the vessel has a slow speed of advance of 1.5 
m/s (3 knots).
    While there was a LF component in the Greek stranding in 1996, only 
mid-frequency components were present in the strandings in the Bahamas 
in 2000, Madeira 2000, and Canaries in 2002. This supports the 
conclusion that the LF component in the Greek stranding was not 
causative (ICES, 2005; Cox et al., 2006). In its discussion of the 
Bahamas stranding, Cox et al. (2006) stated: ``The event raised the 
question of whether the mid-frequency component of the sonar in Greece 
in 1996 was implicated in the stranding, rather than the low-frequency 
component proposed by Frantzis (1998).'' The ICES in its ``Report of 
the Ad-Hoc Group on the Impacts of Sonar on Cetaceans and Fish'' raised 
the same issues as Cox et al., stating that the consistent association 
of MF sonar in the Bahamas, Madeira, and Canary Islands strandings 
suggest that it was the MF component, not the LF component, in the NATO 
sonar that triggered the Greek stranding of 1996 (ICES, 2005). The ICES 
(2005) report concluded that no strandings, injury, or major behavioral 
change have been associated with the exclusive use of LF sonar.
    Beaked whales have been the subject of particular concern in 
connection with strandings. Like most odontocetes, they have relatively 
sharply deceasing hearing sensitivity below 2 kHz (Cook et al. (2006), 
Richardson et al. (1995) and Finneran et al. (2002)). The SURTASS LFA 
sonar source frequency is below 500 Hz. If a cetacean cannot hear a 
sound or hears it poorly, the sound is unlikely to have a significant 
behavioral impact (Ketten, 2001). Therefore, it is unlikely that LF 
transmissions from LFA sonar would induce behavioral reactions from 
animals that have poor LF hearing. Though highly unlikely, the sounds 
could damage tissues even if the animal does not hear the sound, but 
this would have to be within 1,000 m (3.280 ft) of the array, where 
detection would be very likely, triggering shutdown.

Estimates of Potential Effects on Marine Mammals

    The effects on marine mammals from operation of SURTASS LFA sonar 
will not be the lethal removal of animals. In addition, while possible, 
Level A harassment, if it occurs at all, is expected to be so minimal 
as to have no effect on rates of reproduction and survival of affected 
marine mammal species. Based on AIM modeling results, the primary 
effects would be the potential for Level B harassment. The Final SEIS 
Subchapter 4.4 provides the risk assessment methodology applied to 
SURTASS LFA sonar operations for the annual LOA applications for 
proposed operational areas.
    Tables 4.4-2 through 4.4-10 in the Final SEIS provide, through a 
case study based on the results of the Navy's 4th LOA, estimates of the 
percentage of stocks potentially affected for SURTASS LFA sonar 
operations and are based on reasonable and realistic estimates of the 
potential effects to marine mammals stocks specific to the potential 
mission areas. Also, Tables 5 through 8 in the Navy's Final 
Comprehensive Report for the 2002-2007 rule provides annual total 
estimates of percentages of marine mammal stocks potentially affected 
annually during the four years of LFA sonar operations, based on actual 
operations during the period of the LOAs.
    The scenarios chosen by the Navy are not the only possible 
combinations of areas where the SURTASS LFA sonar will operate. The 
potential effects from other scenarios can be estimated by making a 
best prediction of the areas in which the Navy would conduct SURTASS 
LFA sonar operations annually in each oceanic basin area, determining 
from Tables 4.4-2 through 4.4-10 in the Final SEIS the percentage of 
each stock that may potentially be affected, and adding those 
percentages together for each affected stock. Tables 5-8 in the Navy's 
Comprehensive Report indicate that annually Level B harassment may 
affect 0-6 percent for most marine mammal stocks, rising to just over 
11 percent annually for other species (e.g., common dolphins (6.4 
percent), Risso's dolphins (6-8 percent), short-finned pilot whales (6-
9 percent), false killer whales (5-10 percent), Pacific white-sided 
dolphins (6-11 percent) and melon-headed whales (11.2 percent)).
    Also, using updated modeling where appropriate, the Navy will rerun 
AIM when planning missions and, if necessary, modify annual LOA 
requests with an analysis of take estimates prior to any mission in a 
new/different area. For this proposed rule, NMFS is preliminarily 
adopting the Navy estimates shown in Final SEIS (Tables 4.4-2 through 
4.4-10) as the best scientific information currently available.

Proposed Mitigation for Marine Mammals

    NMFS proposes to require the same visual, passive acoustic, and 
active acoustic monitoring of the area surrounding the SURTASS LFA 
sonar array, as required for the current 2002-2007 rule and LOAs, to 
prevent the incidental injury of marine mammals that might enter the 
180-dB isopleth from the SURTASS LFA sonar. These three monitoring 
systems are described in the next section of this document. NMFS also 
proposes the same protocols as in the 2002-2007 rule. Prior to each 
active sonar exercise, the distance from the SURTASS LFA sonar source 
to the 180-dB isopleth will be determined. If, through monitoring, a 
marine mammal is detected within the 180-dB isopleth, the Navy proposes 
to shut down or

[[Page 37412]]

immediately suspend SURTASS LFA sonar transmissions. Transmissions may 
commence/resume 15 minutes after the marine mammal has left the area of 
the 180-dB isopleth or there is no further detection of the animal 
within the 180-dB isopleth. The protocol established by the Navy for 
implementing this temporary shut-down is described in the application. 
As an added safety measure, NMFS again proposes to require a ``buffer 
zone'' extending an additional 1 km (0.54 nm) beyond the 180-dB 
isopleth. This coincides with the detection range of the HF/M3 sonar. 
This 180- dB plus 1 km (0.54 nm) distance will be the established 
mitigation zone for that exercise. Therefore, if a marine mammal is 
detected by the HF/M3 sonar, the SURTASS LFA sonar will be either 
turned off or not turned on. This is a effective mitigation measure 
since testing of the HF/M3 sonar indicates effective levels of 
detection up to 2 km (1.1 nm). At 2 km (1.1 nm), the SPL from the 
SURTASS LFA sonar will be approximately 173 dB, significantly below the 
180 dB threshold for estimating onset of injury. SURTASS LFA sonar 
operators would be required to estimate SPLs before and during each 
operation to provide the information necessary to modify the operation, 
including delay or suspension of transmissions, so as not to exceed the 
mitigation sound field criteria.
    In addition to establishing a mitigation zone at 180 dB plus 1 km 
(0.54 nm) to protect marine mammals, the Navy has established a 
mitigation zone for human divers at 145 dB re 1 microPa(rms) around all 
known human commercial and recreational diving sites. Although this 
geographic restriction is intended to protect human divers, it will 
also reduce the LF sound levels received by marine mammals located in 
the vicinity of known dive sites.
    The Navy also recommended establishing OBIAs for marine mammal 
protection in its Final EIS and SEIS. The Navy evaluated nine sites in 
its Final EIS and SEIS and concluded that marine animals of concern 
(marine animals listed under the ESA and other marine mammals) 
congregate in these areas to carry out biologically important 
activities.
    Based on the Navy's evaluation, NMFS proposes to designate these 
nine sites as OBIAs for LFA sonar. The nine areas are: (1) the North 
American East Coast between 28[deg] N. and 50[deg] N. from west of 
40[deg] W. to the 200-m (656-ft) isobath year-round; (2) the Antarctic 
Convergence Zone, from 30[deg] E. to 80[deg] E. to 45[deg] S., from 
80[deg] E. to 150[deg] E. to 55[deg] S., from 150[deg] E. to 50[deg] W. 
to 60[deg] S., from 50[deg] W to 30[deg] E. to 55[deg] S. from October 
through March; (3) the Costa Rica Dome, centered at 9[deg] N. and 
88[deg] W., year-round; (4) Hawaiian Islands Humpback Whale National 
Marine Sanctuary- Penguin Bank, centered at 21[deg] N. and 157[deg] 30' 
W. from November 1 through May 1; (5) Cordell Bank National Marine 
Sanctuary, boundaries in accordance 15 CFR 922.110 year-round; (6) Gulf 
of the Farallones National Marine Sanctuary, boundaries in accordance 
15 CFR 922.80 year-round; (7) Monterey Bay National Marine Sanctuary, 
boundaries in accordance with 15 CFR 922.30 year-round; (8) Olympic 
Coast National Marine Sanctuary, boundaries within 23 nm of the coast 
from 47[deg]07' N. to 48[deg]30' N. latitude in December, January, 
March, and May; and (9) Flower Garden Banks National Marine Sanctuary, 
boundaries in accordance with 15 CFR 922.120 year-round.
    NMFS also proposes to designate an additional OBIA that was 
recommended by several commenters on the Draft SEIS: The Gully with 
boundaries at 44[deg] 13' N., 59[deg] 06' W. to 43[deg] 47' N., 58[deg] 
35' W. to 43[deg] 35' N., 58[deg] 35' W. to 43[deg] 35' N., 59[deg] 08' 
W. to 44[deg] 06' N., 59[deg] 20' W., year round. NMFS believes this 
area is biologically important for marine mammals, based on its 
importance as habitat for several species of marine mammals, 
particularly the northern bottlenose whale, and its designation as a 
Canadian marine protected area.
    NMFS is also evaluating whether to designate certain areas in the 
Northwestern Hawaiian Islands as OBIAs and solicits public comments and 
information on marine mammal distribution, densities, and the specific 
biologically important activities that take place in these areas. Any 
additional OBIA designations would be made through a separate 
rulemaking process. NMFS proposes to continue the system established in 
the 2002-2007 rule for expanding the number of OBIAs, as described 
later in this document. While retaining the requirement to provide 
notice and