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, 46846-46893 [07-4044]

Agencies

• DEPARTMENT OF COMMERCE
• National Oceanic and Atmospheric Administration

[Federal Register Volume 72, Number 161 (Tuesday, August 21, 2007)]
[Rules and Regulations]
[Pages 46846-46893]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 07-4044]



[[Page 46845]]

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Part III





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; Final Rule

Federal Register / Vol. 72 , No. 161 / Tuesday, August 21, 2007 / 
Rules and Regulations

[[Page 46846]]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

50 CFR Part 216

[Docket No. 070703226-7461-02; 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: Final rule.

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SUMMARY: NMFS, upon application from the U.S. Navy, is issuing 
regulations to govern the unintentional taking of marine mammals 
incidental to Navy operation of the Surveillance Towed Array Sensor 
System Low Frequency Active (SURTASS LFA) Sonar. Issuance of 
regulations, and Letters of Authorization issued under these 
regulations, is required by the Marine Mammal Protection Act (MMPA) 
when the Secretary of Commerce (Secretary), after notice and 
opportunity for comment, finds, as here, that such takes will have a 
negligible impact on the affected species or stocks of marine mammals 
and will not have an unmitigable adverse impact on their availability 
for taking for subsistence uses. These regulations 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.

DATES: Effective from August 16, 2007, through August 15, 2012.

ADDRESSES: 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 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, 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 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.
    The MMPA directs the Secretary to allow the requested incidental 
taking during periods of not more than 5 consecutive years each 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. These regulations do not themselves authorize 
the taking of marine mammals. NMFS authorizes the incidental take 
through ``letters of authorization'' (LOAs) (50 CFR 216.106). Prior to 
issuance of an LOA, NMFS conducts a review of the activity and its 
impact on marine mammals (via the required monitoring, reporting and 
research) to ensure that the MMPA findings continue to be valid.
    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 by Level A and Level B harassment, 
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 rule, and offshore 
biologically important areas (OBIAs)) for a period of time not to 
exceed 5 years. According to the Navy's application, the Navy planned 
to operate the SURTASS LFA sonar system on a maximum of 4 ships in 
areas potentially including the Pacific, Atlantic, and Indian oceans 
and the Mediterranean Sea.
    SURTASS LFA sonar provides 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 use of SURTASS 
LFA

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sonar testing, training, and routine military 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 extends through August 15, 
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 the 
proposed and final rules.

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 sonar 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 sonar 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. 
The parties entered into a Stipulation Regarding Permanent Injunction 
that allowed the Navy to operate 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. The 
Court entered the Stipulation as an Order on October 14, 2003. On July 
7, 2005, following mediation by the parties, the Court amended the 
injunction at Navy's request to expand the potential areas of operation 
based on real-world contingencies. The Navy began work on an SEIS, in 
response to the Court's ruling on the motion for preliminary 
injunction. The Navy's Final SEIS, which was completed in April 2007, 
not only addresses, the concerns identified by the Court in its ruling 
on the merits of the parties' summary judgment motions, but it also 
provides additional information regarding the environment that could 
potentially be affected by the SURTASS LFA sonar systems, and 
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 sonar 
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 sonar 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 employed on both the R/V Cory 
Chouest and the USNS IMPECCABLE (TAGOS 23) did not exceed 174 hours 
annually between August 16, 2002, and August 15, 2006 (Table 4 in the 
Navy's Final Comprehensive Report (Navy, 2007)).
    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 sonar systems are installed on the 
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

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LFA, or CLFA sonar. CLFA sonar consists of smaller, lighter-weight 
source elements than the current LFA sonar 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 sonar systems as presented in Subchapter 2.1 of the Final EIS and 
Final SEIS. Consequently, the potential impacts from CLFA sonar will be 
similar to the effects from the existing SURTASS LFA sonar systems. 
Three CLFA sonar 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 operation in FY 2008 and FY 
2009, 3 in FY 2010 and 4 systems in FY 2011 and FY 2012. At no point 
are there expected to be more than four systems in use, and thus this 
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 through the sea is to think of 
the sound as ``rays.'' As these rays travel through 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 (e.g., there is a low-
frequency cutoff dependent on the thickness of the duct), 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

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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 elevated sound levels. The existence of CZs depends on the 
SSP and the depth of the water. Due to downward refraction at shorter 
ranges, sound rays leaving the near-surface region are refracted back 
to the surface because of the positive sound speed gradient produced by 
the greater pressure at deep ocean depths. These deep-refracted rays 
often become concentrated at or near the surface at some distance from 
the sound source through the combined effects of downward and upward 
refraction, thus causing a CZ. CZs may exist whenever the sound speed 
at the ocean bottom, or at a specific depth, exceeds the sound speed at 
the source depth. Depth excess, also called sound speed excess, is the 
difference between the bottom depth and the limiting, or critical 
depth.
    CZs vary in range from approximately 18 to 36 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 sonar 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 
(e.g., sediments), 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 sonar 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 sonar signals are CZ 
and bottom interaction (at depths less than 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.

Comments and Responses

    On September 28, 2006 (71 FR 56965), NMFS published a Notice of 
Receipt of Application on the U.S. Navy SURTASS LFA sonar MMPA 
application and invited interested persons to submit comments, 
information, and suggestions concerning the application and the 
structure and contents of regulations. Those comments were considered 
in the development of the proposed rule. A proposed rule for renewal of 
the regulations governing SURTASS LFA sonar MMPA authorization was 
published on July 9, 2007 (72 FR 37404) with a 15-day public comment 
period. During the two comment periods, comments were received from a 
large number of organizations and individuals. Those organizations 
include the Marine Mammal Commission (Commission), the Natural 
Resources Defense Council (NRDC), Earth Island Institute (EII), 
Acoustic Ecology Institute (AEI), Animal Welfare Society (AWI), 
Cetacean Society Institute (CSI), Seaflow, International Ocean Noise 
Coalition, Olympic Coast Alliance, Citizens Opposing Active Sonar 
Threats, Ocean Care, Gesselschaft zur Rettung der Delphine, SBOOHER, 
Ocean Conservation Research, Friends of the San Juans, World Society 
for the Protection of Animals. We have addressed all comments on the 
proposed rule. We also responded to comments that appear to be directed 
solely at the draft SEIS, although we did not address comments strictly 
related to non-marine mammal issues. See the Navy's Final SEIS, which 
NMFS has adopted under NEPA.

Activity Concerns

    Comment 1: The U.S. Navy seeks a blanket exemption to do harm to 
all marine animals in 80 percent of the world oceans with only minor 
mitigation measures taken. Expanding the SURTASS program into 80 
percent of the world's oceans would make the task of monitoring the 
impacts impossible. An LOA granted would not meet the ``negligible 
impact'' condition and would violate the ``unmitigable adverse impact'' 
constraints indicated in the MMPA LOA process.
    Response: The Navy is not seeking a ``blanket exemption'' from the 
MMPA, but rather is requesting that NMFS issue regulations to govern 
the incidental take of marine mammals under Section 101(a)(5)(A) of the 
MMPA. Under these regulations the Navy must apply annually for a letter 
of authorization (LOA) that would exempt the taking of marine mammals 
incidental to the Navy's use of SURTASS LFA sonar from the MMPA's 
general moratorium on the taking of marine mammals for that year, as 
long as the sonar use was consistent with these regulations and the 
terms of the LOA. In its LOA application, the Navy must specify where 
it will operate SURTASS LFA sonar for that year and take authorization 
would be limited to that area. Under the regulations, the total area 
that would be available for SURTASS LFA sonar operations over the five-
year period is about 70-75 percent of the world's oceans. This in no 
way equates to LFA sonar operations affecting even close to 70-75 
percent of the world's ocean area at any given time. Each year, based 
on its projected operational needs, the Navy will identify for which 
particular geographic areas, out of the total available area, it is 
requesting take authorization through an LOA. The first authorization 
is for only two SURTASS LFA sonar vessels both operating in the Western 
Pacific Ocean. Eventually, the Navy plans to have 4 vessels in 
operation, but even if

[[Page 46850]]

all 4 vessels operated in 4 different oceans, the area ensonified would 
come nowhere close to 70-75 percent of the world's ocean area. 
Therefore, SURTASS LFA sonar sound will not simultaneously affect 70-75 
percent of the world's oceans. In addition, NMFS has determined that 
incidental harassment takings by SURTASS LFA sonar operations during 
the effective time period (1 year) of any LOA issued to the Navy 
pursuant to these regulations must not exceed 12 percent of any marine 
mammal stock.
    The sound pressure level (SPL) that is capable of potentially 
causing injury to an animal is within approximately 1 km (0.54 nm) of 
the ship. For the purposes of analyses using the Acoustic Integration 
Model (AIM) and the risk continuum, there is a 50 percent risk of 
significant change in a biologically important behavior for a marine 
mammal exposed to a received level (RL) of 165 dB RMS. The range from 
the SURTASS LFA sonar vessel for this received level, which could cause 
behavioral disruption but not injury, could extend to 25 to 65 km (13.5 
to 35.1 nm). The received level at the surface along any straight path 
away from the ship would not decline logarithmically over distance, as 
would be expected if the sound spread by spherical spreading alone. The 
reason is that, for CZ propagation, the sound moves in an undulating 
path with turning points near the surface and near the bottom, where 
sound is refracted either downward (near surface) or upward (near 
bottom). Turning points near the surface, termed caustics, occur 
approximately every 30 nm (56 km). The received level at the surface 
would be high at the caustics but low in between them because most of 
the sound energy there would be found at great depth. While the 
regulations permit the Navy to seek authorization through an LOA to 
take marine mammals while operating SURTASS LFA sonar in many of the 
world's oceans and SURTASS LFA sonar signal can be detected at several 
hundred miles using sophisticated listening gear, SURTASS LFA sonar's 
potential to cause injury or affect behavior is limited to relatively 
close to the ship. Thus, the impact of SURTASS LFA sonar is not global 
in scope. Moreover, monitoring to ensure that marine mammals are not 
injured is not impossible, as the commenter suggests, given the limited 
area around the vessel that is ensonified at decibel levels up to 180 
dB, and the demonstrated effectiveness of the Navy's tripartite 
(visual, acoustic, and HF/M3) monitoring scheme.
    Since the SURTASS LFA sonar will not operate in Arctic waters, 
there will not be an unmitigable adverse impact on relevant subsistence 
uses of marine mammals. That determination is provided later in this 
document. NMFS also believes the negligible impact standard has been 
met, as described in this final rule.
    Comment 2: The Navy is proposing to expand the use of LFA sonar, 
both through expansion of use areas geographically throughout the 
world's oceans and through doubling the number of LFA sonar array 
ships. The Navy is also admitting to the use of CLFA sonar in ``shallow 
littoral ocean regions'' and do not discuss the characteristics of CLFA 
sonar in the Final SEIS.
    Response: While the number of SURTASS LFA sonar vessels will 
increase from 2 to 4 vessels over the course of the five-year rule, the 
Navy is not increasing the number of SURTASS LFA sonar systems beyond 
what was analyzed in the January 2001 Final EIS. That document analyzed 
the potential impacts of up to four SURTASS LFA sonar systems. As 
stated in the Navy's Record of Decision (ROD) (67 FR 48145, July 23, 
2002), the Navy determined that only two of the four systems would be 
operational during the timeframe of the 2002-2007 regulations governing 
the taking of marine mammals incidental to LFA sonar testing and 
training. For that reason, NMFS addressed taking marine mammals 
incidental to operation of only two systems under the initial five year 
Final Rule in 2002. Installation and deployment of the third and fourth 
LFA sonar systems were postponed until after FY 2007. Because of this 
delay, the decision in the Navy Record of Decision (ROD) and NMFS' MMPA 
determinations covered the employment of only two SURTASS LFA sonar 
systems. Therefore, the use of SURTASS LFA sonar, analyzed here, does 
not exceed the originally analyzed four systems during the timeframe of 
the requested second five year set of MMPA regulations.
    In addition, the Navy's proposal to deploy SURTASS LFA sonar in a 
number of oceans is not new. The Navy's Final EIS proposed, and NMFS 
original Final Rule and regulations addressed, deployment of SURTASS 
LFA sonar throughout most of the world's oceans. As stated in the Final 
SEIS, these systems will be employed as required for security 
operations in the oceanic areas as presented in Figure 1-1 of the Final 
EIS. Potential operations could occur in the Pacific, Atlantic, and 
Indian Oceans, and the Mediterranean Sea. Large oceanic areas are 
restricted from operations, including the Arctic and Antarctic Ocean 
areas, as are all offshore areas within 12 nm (22 km) of land, and 
OBIAs (Table 2-4 of the SEIS). The limitation of SURTASS LFA operation 
to the Western Pacific Ocean was a product of the parties' negotiations 
over the Stipulated Permanent Injunction.
    Nevertheless, while the number of systems may increase under this 
Final Rule and the Navy may seek authorization to use SURTASS LFA sonar 
in more places than it could under the terms of the permanent 
injunction, the maximum permissible impact to any particular species or 
stock remains the same, since the Navy's overall use of SURTASS LFA 
sonar can have no more than a negligible impact on marine mammal 
species and stocks. Consistent with its findings in the original rule, 
NMFS has determined that takings by SURTASS LFA sonar operations during 
the effective time period (1 year) of any LOA issued to the Navy 
pursuant to these regulations must not exceed 12 percent of any marine 
mammal stock.
    As stated in the Final SEIS Subchapter 1.2.3 and 2.1, compact LFA 
sonar (CLFA sonar) sonar is an upgrade and modification to the SURTASS 
LFA sonar system necessary to install and operate on the smaller 
VICTORIOUS Class T-AGOS 19 Class ocean surveillance ships. The 
operational characteristics of the active system components installed, 
or to be installed, on the R/V Cory Chouest, USNS IMPECCABLE, and 
VICTORIOUS Class vessels are provided in Final SEIS Subchapter 2.1.1. 
The characteristics of LFA sonar and the upgrade and modifications for 
the T-AGOS 19 installations are essentially the same. The frequency 
requirements for the CLFA to be installed onboard the VICTORIOUS Class 
(T-AGOS 19 Class) vessels are within the 100 to 500 Hz range for LFA 
sonar and the transmit array also consists of 18 transducers with a 
similar source level.
    Subchapter 1.1.3 of the Final SEIS provides a definition of the 
term ``littoral'' as used by the U.S. Navy and explains the ways in 
which the use of the term as a tactical designation differs from its 
use as a geographic term. The littoral operating environment does not 
necessarily include or exclude any waters because of depth; it can 
include both deep and shallow water. However, under any of the 
alternatives analyzed in the Final SEIS, LFA sonar would not operate 
inside of 12 nm (22 km) from any coastline. The use of SURTASS LFA 
sonar in coastal environments was discussed in Response to Comments 
(RTCs) 1-1.4 and 3-2.8 in the Final EIS.

[[Page 46851]]

    Comment 3: With regard to noise-producing activities, NMFS must 
describe source levels, frequency ranges, duty cycles, and other 
technical parameters relevant to determining the potential impacts of 
an MMPA authorization.
    Response: The NMFS action is the issuance of regulations and LOAs 
to the Navy for taking marine mammals incidental to SURTASS LFA sonar 
operations and determining whether SURTASS LFA sonar is having a 
negligible impact on affected marine mammal species and stocks, not 
whether LFA sonar operations and other noise producing activities are 
having a negligible impact on affected species and stocks of marine 
mammals (and species/stocks not affected by LFA sonar, but potentially 
by other noise-producing activities). In that regard, all technical 
parameters relevant to the impact analysis, including those listed by 
the commenter, were provided in the project descriptions for SURTASS 
LFA sonar in both the Final EIS (DON, 2001) Subchapters 2.1.1 and 
2.3.2.2 and in RTCs 2-1.1 and 2-1.2a; and in the Final SEIS Subchapter 
2.1.1.
    Comment 4: There are at least five Navy SWATH vessels already built 
and outfitted with operational LFA sonars.
    Response: Four VICTORIOUS class Ocean Surveillance ships were built 
between 1991 and 1993. As stated in the SEIS Subchapter 2.1, there are 
no LFA sonar systems deployed on these vessels at this time. The 
projected LFA sonar/CLFA sonar system availabilities are shown in the 
Final SEIS Figure 2-2, which includes future installations onboard the 
VICTORIOUS Class vessels.
    Comment 5: It is only a matter of time before many other 
industrialized nations follow suit and the oceans become a cacophony of 
LFA sonar systems using loud noise to try and find each other in an 
increasingly loud environment. The U.S. should re-examine this ``need'' 
and come up with a better way to find these quiet submarines.
    Response: This comment is beyond the scope of this rulemaking. As 
explained in the Final EIS, subchapter 1.2.1, the Navy has considered 
other alternatives and determined that SURTASS LFA sonar best addresses 
its need for reliable long-range detection of potentially hostile quiet 
submarines.
    Comment 6: At peak power, the Navy's LFA sonar system sends out 
pulses of sound underwater at least the equivalent of standing five 
feet away from the Saturn rocket on liftoff.
    Response: While an accurate source level of the Saturn V is not 
known, the comparison of this, or any other rocket, to LFA sonar is 
inappropriate. The sound generated by a Saturn V rocket, or any rocket 
in general, is broadband and generates a different frequency spectrum 
than that of LFA sonar, and travels in a significantly different 
transmission pattern. The Saturn C 1 rocket (a predecessor to the 
Saturn I rocket, which had about 1,600,000 lbs of thrust) was projected 
to have produced acoustic levels as high as 205 dB (in air) from a 
distance of 305 meters. Some sources suggest that the sound levels 
produced by the Saturn V (during the launch of Apollo 15, the first 
stage of the Saturn V generated 7,823,000 lbs of liftoff thrust) may 
have been as high as 220 dB (in air) (Benson and Faherty, 1978). As 
sound is perceived differently underwater than it is in air, sound 
propagation and transmission losses in each case are subject to 
differing factors, including terrain, wind, and air temperature, and in 
the case of LFA, water salinity, temperature and depth. Furthermore, 
sound levels are typically provided with a reference level, which 
depends on whether the sound is in air (reference of 20 microPascals) 
or water (reference of 1 microPascal). Despite it being inappropriate 
to compare a sound level in air with that in water (or vice versa), 
some simplified conversion or correction factors are available to 
provide a very generic comparison. Therefore, when corrected to the 
equivalent sound levels in water (based on pressure and impedance 
differences of the two media), the above acoustic levels of 205 dB in 
air and 220 dB in air would be approximately 266.5 and 281.5 dB in 
water, respectively (Please see Final EIS Appendix B, Subchapter 
B.3.2). These sound levels are 100 to 10,000 times louder than the LFA 
sonar source.
    Comment 7: NMFS should require that the U.S. Navy avoid or 
eliminate triangulation of sonar whether they are doing exercises with 
other U.S. Navy ships or with those from other nations.
    Response: Triangulation is only necessary for passive acoustics. 
Triangulation is not necessary for active acoustics because it gives 
the operator range and bearing. However, the focus of the comment seems 
to be on the use of multiple LFA sonar ships, which is discussed in the 
Final SEIS, (Subchapters 4.4.4 and 4.6.1.2) and in the Final EIS 
(Subchapter 4.2.7.4). The Final EIS states that the vast majority of 
operations will involve only one ship. This is due to the limited 
number of ships of SURTASS LFA sonar systems planned to be built and 
the limited operational conditions that could warrant the use of two 
sources in proximity to each other. The remote possibility exists that 
operational requirements or training exercises could require two 
sources simultaneously in one geographic region, for example the 
Northwest Pacific Ocean where LFA sonar vessels have been operating. 
The effect of the presence of two sources transmitting in one area can 
be conservatively approximated by doubling the single source potential 
effects provided for that site. An example of these effects can be seen 
in Table 4-2.13 of the Final EIS. However, even if more than one source 
operates in a single geographic area, impacts to marine mammals remain 
capped by the negligible impact requirement. To ensure that SURTASS LFA 
sonar operations have no more than a negligible impact over five years, 
not more than 12 percent of any marine mammal stock may be taken, by 
harassment, in a single year, regardless of how many SURTASS LFA sonar 
sources are operating in the area.
    Comment 8: There are plenty of safe alternatives to active sonar 
that the Navy could pursue, such as passive sonar, non-acoustic 
sensors, and Integrated Sensory Networks.
    Response: The comment is beyond the scope of NMFS' rulemaking for 
this action. Non-acoustic alternative underwater detection technologies 
are discussed in the Final EIS, Subchapter 1.2.1.

MMPA Concerns

    Comment 9: NMFS should consolidate all necessary and relevant 
information from the multiple existing sources of information 
describing the proposed actions in the proposed rule.
    Response: NMFS does not consider it necessary to consolidate all 
necessary and relevant information on LFA sonar and its impacts on 
marine mammals into the proposed and/or final rules. In the proposed 
and final rules, NMFS has continued and updated the information 
contained in the preamble to the 2002 final rule. NMFS believes that 
this information provides the necessary level of detail needed for it 
to make the determinations required under the MMPA and for the public 
to review this information. This document also reflects the findings of 
the Final EIS, with the data and findings of the Final SEIS. These 
documents and others, which are available on the Navy SURTASS LFA sonar 
homepage (see ADDRESSES) provide the ``consolidated information'' that 
the commenter requested.
    Comment 10: The Commission states that any regulations proposing to 
issue an incidental taking authorization should include information on 
specified geographic locations where sonar is

[[Page 46852]]

expected to be deployed and the species and number of marine mammals 
that may be taken in each of those locations.
    Response: While the NDAA removed references to the specified 
geographical region and small numbers requirements for military 
readiness activities, NMFS still needs to know where activities would 
take place and the estimated level of take to inform its negligible 
impact determination. In order to do so, NMFS considered ``worst-case'' 
estimates for purposes of the negligible impact determination as well 
as an annual 12 percent per-stock ``cap'' for marine mammals regardless 
of where and when LFA sonar will be operating (or even how many LFA 
sonar systems are in operation annually). This rulemaking also 
considered the oceans and areas where LFA sonar may and may not 
operate. The rule does not specify the specific location where LFA 
sonar will be deployed and the number of marine mammals that may be 
taken in those locations because these are determined annually through 
various inputs such as mission duration and season of operation [which 
are calculated in the annual applications for LOAs].
    Comment 11: The Commission recommends the existing annual review 
process for LOAs should be expanded to include public review and 
comment. The NRDC believes issuance of LOAs without notice and comment 
violates MMPA section 101(a)(5)(A) because, it says, each year's 
authorization will involve new take and negligible impact analyses and 
potentially new exercise areas that are not modeled in the Navy's SEIS.
    Response: NMFS does not agree. Under section 101(a)(5)(A), notice 
and opportunity for public comment must be afforded before the 
Secretary authorizes the incidental take of marine mammals, makes a 
negligible impact determination, and issues the required regulations. 
NMFS published the proposed regulations on July 9, 2007 (72 FR 37404), 
providing the required notice and opportunity for public comment. That 
proposed rule contained NMFS' negligible impact determination for the 
five-year period and proposed mitigation, monitoring, and reporting 
requirements. It also considered the Navy's estimates of take for the 
five-year rule period. Section 101(a)(5)(A) of the MMPA does not 
require the regulations to specify the number of marine mammals that 
may be taken, only the permissible methods of taking and means of 
effecting the least practicable adverse impact.
    As stated in the proposed rule and the Navy's Final EIS, estimates 
were derived based on modeling sites, since it was not practical to 
model all areas where the system might be operated. Final EIS p. 4.2-1. 
These sites represented the upper bound of impacts expected from 
operation of SURTASS LFA sonar. Final EIS p. 4.2-3; see Final EIS 
tables 4.2-1, 4.2-4, 4.2-10, 4.2-11, and 4.2-12. If LFA sonar 
operations occur in a non-modeled area, the take estimates would most 
likely be less than those obtained from the most similar site that was 
modeled. Final EIS p. 4.2-3. As stated in the SEIS, the assumptions of 
the Final EIS are still valid and have been incorporated by reference 
into the SEIS p. 4-39, 40. Moreover there are no new data that 
contradict the assumptions or conclusions made in subchapter 4.2 of the 
FEIS. Thus, it was not necessary to reanalyze potential acoustic 
impacts in the SEIS.
    The risk assessment for each planned mission site for each vessel 
is performed annually and is part of the Navy's annual mission 
intention (LOA application) letter. In its annual LOA applications, the 
Navy must project where it intends to operate during the period of the 
annual LOAs and provide NMFS with reasonable and realistic risk 
estimates of the marine mammal stocks in the proposed areas of 
operations. This process utilizes the best available data and is 
detailed in the SEIS including a case study. SEIS pp. 4-37 to 4-51. 
During the initial steps of the risk analysis process, if the take 
estimates exceed those required under the regulations (including the 
annual 12 percent per-stock cap), than the mission areas are changed or 
refined and the analysis is reinitiated. After receipt of an LOA 
application, NMFS reviews the activity (and previous annual reports) to 
ensure it remains within the parameters of the rule and the negligible 
impact assessment.
    NMFS' general implementing regulations for section 101(a)(5)(A) of 
the MMPA, which have been in effect since 1982 and which governed the 
last rulemaking for SURTASS LFA sonar incidental take, set up the 
framework under which NMFS issues LOAs that an applicant must obtain 
before any incidental take is authorized. 50 CFR 216.106(a). The 
purpose of the requirement for obtaining LOAs is to ensure the 
authorized taking will be consistent with the original findings. See 47 
FR 21248, 21251 (May 18, 1982). Therefore, issuance of an LOA is based 
on a determination that the level of taking will be consistent with the 
findings made for the total taking allowable under the specific 
regulations for the specified activity. 50 CFR 216.106(b). The 
reporting requirements under these specific SURTASS LFA sonar 
regulations and LOAs require the Navy to provide both quarterly and 
annual reports to NMFS. In these reports, the Navy must provide 
estimated percentages of marine mammal species/stocks potentially 
affected for each quarter and annually. NMFS' general implementing 
regulations do not require the agency to provide notice and comment for 
LOAs. However, if NMFS were to obtain information that calls into 
question the validity of its determinations in this rule, the agency 
could withdraw or suspend authorization to take marine mammals if the 
Secretary, through the Assistant Administrator for Fisheries, finds, 
after notice and opportunity for public comment, that the regulations 
are not being substantially complied with, or the taking allowed 
pursuant to the regulations is having or may have more than a 
negligible impact on marine mammal species or stocks. 50 CFR 
216.106(e). The requirement for notice and comment does not apply if an 
emergency exists that poses a significant risk to the wellbeing of the 
species or stocks of marine mammals concerned. 50 CFR 216.106(f).
    Comment 12: The Commission states that NMFS should address the 
requirement of the NDAA that personnel safety, practicality of 
implementation, and impact on the effectiveness of the military 
readiness activity be considered in making a ``least practicable 
adverse impact'' determination in the proposed rulemaking.
    Response: NMFS agrees with the Commission and added a discussion of 
the NDAA in the proposed and final rules.
    Comment 13: The NRDC states the Navy fails to present evidence of 
negligible impact. Agencies must make every attempt to obtain and 
disclose data necessary to their analysis. This is important when the 
program's impacts depend on newly emerging data. The Navy fails to take 
account of significant new information that has emerged since January 
2001 concerning marine mammal thresholds of injury, hearing loss, and 
significant behavioral change.
    Response: NMFS believes the MMPA requires a determination of 
negligible impact to be based on the best available data. NMFS believes 
the best available data were used in the Final SEIS, NMFS' 2002 final 
rule, the Navy 2006 MMPA application and this final rule, to estimate 
the potential impacts on the environment. Information that the 
commenter (and others) believe

[[Page 46853]]

contradict this determination by NMFS is addressed throughout this 
document.
    Comment 14: A number of commenters were of the opinion that a 15-
day comment period for the proposed rule is too short to review the 
material and not in compliance with the Administrative Procedure Act 
(APA).
    Response: The 15-day comment period on the proposed rule provided 
an adquate opportunity for public comment. In addition to the comment 
period on the proposed rule, members of the public had a 30-day public 
comment period on the Navy's application for renewal of NMFS' 
regulations (71 FR 56965, September 28, 2006) and a 92-day public 
comment period (including three public hearings) for the Navy's Draft 
SEIS on SURTASS LFA sonar (which contains much of the underlying 
analysis for this proposed rule, affording significant opportunity for 
public participation). In addition, the proposed rule is substantially 
similar to the 2002-2007 rule, which underwent a 75-day public comment 
period, including public hearings in Los Angeles, CA, Honolulu, HI, and 
Silver Spring, MD. There have been no significant scientific 
advancements or other developments since the previous rule that would 
necessitate a longer period for public comment.
    Comment 15: It is well-established that mid-frequency (MF) sonar 
negatively impacts marine mammals, even resulting in fatalities, with 
the U.S. Navy having admitted direct responsibility for past beachings. 
The effects of LF sonar appear to be less understood at this time, but 
the enormous range of ocean impacted by sonar makes it incumbent upon 
us to fully understand its effects before authorizing its widescale 
use. The Precautionary Principle should be applied before issuing a 
permit.
    Response: NMFS used conservative assumptions for identifying and 
analyzing potential impacts to the environment, including marine 
mammals. SURTASS LFA sonar has been operating under NMFS regulations 
for the last five years without any reports of Level A harassment. The 
evidence to date, including recent scientific reports, supports the 
conclusion that operation of the U.S. Navy's LFA sonar does not result 
in marine mammal strandings. For further information on strandings and 
MF sonar, please see comments 8, 32, 33, 47, and 49 for further 
analyses on strandings.
    Comment 16: I request a moratorium on any use of this technology in 
the oceans, at the levels currently used, until further tests are 
conducted on the foundational species in the food chain of the marine 
environment.
    Response: Research using LFA sonar technology has been conducted on 
several species in the food chain, including whales (blue, fin, grey, 
and humpback whales) and on fish (catfish, a hearing specialist, and 
trout; reference species for salmon and a hearing generalist). This 
research is discussed later in this document (see Research Concerns). 
NMFS believes the data are sufficient to go forward, recognizing that 
more research would be valuable.

Marine Mammal Impact Concerns

    Comment 17: The NRDC states that the Navy sets its threshold for 
hearing loss or ``threshold shift'' at 180 dB re: 1 microPa (RMS) for a 
single 100-second ``ping'' of exposure. The analysis is based on data 
from humans and other terrestrial mammals and relies on a limited set 
of data on marine mammals. The Navy has established a sliding scale for 
behavioral impacts. The Final SEIS fails to incorporate several recent 
studies on the effects of low-frequency sound on various marine mammal 
species. Also, the Navy's standard fails to take proper account of 
chronic impacts, from behavioral changes as well as from certain non-
auditory physiological impacts such as stress. The Final SEIS and MMPA 
application disregard recent evidence indicated the potential for 
masking to interfere with long-distance mating behavior in mysticetes. 
The Navy standard is out of step with how the potential for behavioral 
impacts has been assessed in other contexts. Last, the Navy does not 
consider the impact that behavioral changes in species such as fish may 
have on marine mammals foraging.
    Response: NMFS believes that the latest information on impacts of 
underwater sounds on marine mammals and fish is contained in the Navy's 
Draft and Final SEIS, and summarized in the Navy's application. NMFS 
addresses the masking issue in comment 19 and elsewhere in this 
document.
    As stated in the Final EIS, the 180-dB criterion for the purpose of 
SURTASS LFA sonar analysis is that all marine animals exposed to 
received levels (RLs) greater than 180-dB rms are evaluated as if they 
are injured. In its 2002 Final Rule for SURTASS LFA sonar, NMFS stated 
that temporary threshold shift (TTS) is not an injury. Since the 
boundary line between TTS and permanent threshold shift (PTS) is 
neither clear, definitive, nor predictable for marine mammals, NMFS has 
adopted (as a conservative estimate) 20 dB of TTS to define the onset 
of PTS (i.e., a temporary shift of 20 dB in hearing threshold) (67 FR 
46711, July 16, 2002). As noted in Schlundt et al. (2000), bottlenose 
dolphins and belugas exposed to 1-sec signals at 400 Hz did not exhibit 
TTS after exposures to maximum RLs of 193-dB sound exposure level 
(SEL)) (which would be equivalent to a received level of 193 dB re: 1 
microPascal (RMS) since the duration is 1-sec). The point must be made 
that while dolphins and belugas responses at 400 Hz are valid for those 
species, these results probably do not generalize to large whales 
(e.g., baleen whales).
    In the Schlundt et al. (2000) research, dolphins and belugas did 
not have TTS in response to 400 Hz at RLs of 193 dB SEL, but they did 
have TTS in response to higher frequencies (where they are more 
sensitive) at the same level. It is reasonable to assume that the TTS 
threshold value from odontocetes at their frequency of highest 
sensitivity is applicable to larger animals and lower frequencies that 
are in the range of their best hearing sensitivity. This extrapolation 
is based on the fundamental similarity of cochlear structure between 
odontocetes and mysticetes. As a result, if it were assumed that 193 dB 
SEL was the onset of TTS (a conservative assumption because TTS was not 
observed at an RL of 193 dB SEL), then onset of PTS would be 20 dB 
above that, at 213 dB RL (SEL). This number is based on a signal of one 
second in duration. Using a 10 Log (T/Ti) where Ti is 1 second, then 
for a maximum 100-sec LFA sonar signal, a 20-dB adjustment must be 
made, meaning that the onset of PTS would be 193 dB RL (SEL). This 
value is above the conservative LFA sonar criterion of 180 dB for 
injury. A more detailed discussion is provided in the Final EIS RTCs 4-
6.13 and 4-6.38 and the 2002 Final Rule RTCs MMIC8, MMIC9, SIC40, 
SIC58, and SIC59.
    In addition, recent data on critical ratios (CRs) in pinnipeds is 
discussed in the Final SEIS Subchapter 4.3.5. A CR is the difference 
between sound level for a barely audible tone and the spectrum level of 
background noise at nearby frequencies (Richardson et al., 1995). These 
data indicate that the CRs for pinnipeds are lower in magnitude than 
for terrestrial animals (Southall et al. 2003). Southall et al. (2003), 
in describing their CR results, state that ``It is reasonable to 
speculate that acoustic signal production and reception in typically 
noisy marine environments have led to selection for enhanced ability to 
detect signals in noise.'' Therefore these new CR data indicate that 
pinnipeds may be pre-adapted for detecting biologically important 
signals in high noise environments.

[[Page 46854]]

Furthermore, the lower critical bandwidths of the pinniped auditory 
filters has the effect of decreasing the probability of masking of 
signals by noise at a different frequency (Southall et al., 2000). 
Nevertheless, NMFS believes pinnipeds remain as susceptible as any 
species to masking of signals by noise in the same frequency band.
    The Final SEIS also considered recent studies on LF sound and 
injury. In regard to injury, the issue of resonance is addressed in the 
Final SEIS (RTC 2.5.2). The analysis by the Navy (Cudahy and Ellison, 
2002), reports on two workshops on acoustic impacts (DOC, 2002: Cox, et 
al. 2006), and the National Research Council (NRC) Ocean Studies Board 
(NRC, 2003) support the conclusion that resonance from LFA sonar 
operations is not a ``reasonably foreseeable'' impact. 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 MF sonar exposure. They also stated that it is 
premature to judge acoustically mediated bubble growth as a potential 
mechanism and recommended further studies to investigate the 
possibility.
    The NRC Report (2003) discusses acoustically-induced stress in 
marine mammals. The NRC stated that sounds resulting from one-time 
exposure are less likely to have population-level effects than sounds 
that animals are exposed to repeatedly over extended periods of time. 
The NRC also cited controlled laboratory investigations of the response 
of cetaceans to noise that have shown cardiac responses (Miksis et al., 
2001 IN: NRC, 2003) but have not shown any evidence of physiological 
effects in the blood chemistry parameters measured. Beluga whales 
exposed for 30 minutes to 134-153 dB received level (RL) playbacks of 
noise with a synthesized spectrum matching that of a semisubmersible 
oil platform (Thomas et al., 1990b IN: NRC, 2003) showed no short-term 
behavioral responses and no changes in standard blood chemistry 
parameters or in catecholamines. Preliminary results from exposure of a 
beluga whale and bottlenose dolphin to a seismic watergun with peak 
pressure of 226 dB source level (SL) showed no changes in 
catecholamines, neuroendocrine hormones, serum chemistries, lymphoid 
cell subsets, or immune function (Romano et al., 2001 IN: NRC, 2003).
    The NRC Report (2003) also stated that although techniques are 
being developed to identify indicators of stress in natural 
populations, determining the contribution of noise exposure to those 
stress indicators will be very difficult, but important, to pursue in 
the future when the techniques are fully refined. There are scientific 
data gaps regarding the potential for LFA sonar to cause stress in 
marine animals. Even though an animal's exposure to LFA sonar may be 
more than one time, the intermittent nature of the LFA sonar signal, 
its low duty cycle, and the fact that both the vessel and animal are 
moving, means that there is a very small chance that LFA sonar exposure 
for individual animals and stocks would be repeated over extended 
periods of time, such as those caused by shipping noise. There is 
sufficient information available to permit analysis and decision 
making. Therefore, impacts from stress are not a reasonably foreseeable 
significant adverse impact on marine mammals from exposure to LFA 
sonar.
    In studying potential alerting stimuli for North Atlantic right 
whales, Nowacek et al. (2003) found that underwater sounds with an 
acoustic structure similar to their alert stimulus at RLs of 133-148 dB 
are likely to disrupt feeding behavior for the duration of the sound 
exposure, with return to normal behavior within minutes of when the 
sound was turned off. Their results are consistent with those of the 
LFS Scientific Research Program (SRP), which exposed baleen whales to 
RLs ranging from 120 to 155 dB, detecting only minor, short-term 
behavioral responses (please see Final EIS, Subchapter 4.2.4.3 for more 
information). The LFA sonar risk function is based on the LFS SRP 
results.
    Concern that the LFA sonar signal may cause right whales to surface 
and thus be more vulnerable to ship strikes is not well founded because 
the vessels only move at about 5.6 km/hr (3 knots) (significantly lower 
than normal ship speeds) and LFA sonar mitigation measures will detect 
any large whales well before they enter the LFA sonar zone, at which 
time LFA sonar operations would be suspended.
    Comment 18: A number