Taking and Importing Marine Mammals; U.S. Navy's Atlantic Fleet Active Sonar Training (AFAST), 60754-60833 [E8-23617]

Agencies

• DEPARTMENT OF COMMERCE
• National Oceanic and Atmospheric Administration

[Federal Register Volume 73, Number 199 (Tuesday, October 14, 2008)]
[Proposed Rules]
[Pages 60754-60833]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: E8-23617]



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Part II





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; U.S. Navy's Atlantic Fleet Active 
Sonar Training (AFAST); Proposed Rule

Federal Register / Vol. 73, No. 199 / Tuesday, October 14, 2008 / 
Proposed Rules

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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

50 CFR Part 216

[Docket No. 0080724897-8900-01]
RIN 0648-AW90


Taking and Importing Marine Mammals; U.S. Navy's Atlantic Fleet 
Active Sonar Training (AFAST)

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 (Navy) for 
authorization to take marine mammals incidental to training activities 
conducted off the U.S. Atlantic Coast and in the Gulf of Mexico for the 
period of January 2009 through January 2014. Pursuant to the Marine 
Mammal Protection Act (MMPA), NMFS is proposing regulations to govern 
that take and requesting information, suggestions, and comments on 
these proposed regulations.

DATES: Comments and information must be received no later than November 
13, 2008.

ADDRESSES: You may submit comments, identified by 0648-AW90, by any one 
of the following methods:
     Electronic Submissions: Submit all electronic public 
comments via the Federal eRulemaking Portal https://www.regulations.gov.
     Hand delivery or mailing of paper, disk, or CD-ROM 
comments should be addressed to Michael Payne, Chief, Permits, 
Conservation and Education Division, Office of Protected Resources, 
National Marine Fisheries Service, 1315 East-West Highway, Silver 
Spring, MD 20910-3225.
    Instructions: All comments received are a part of the public record 
and will generally be posted to https://www.regulations.gov without 
change. All Personal Identifying Information (for example, name, 
address, etc.) voluntarily submitted by the commenter may be publicly 
accessible. Do not submit Confidential Business Information or 
otherwise sensitive or protected information.
    NMFS will accept anonymous comments Enter N/A in the required 
fields, if you wish to remain anonymous). Attachments to electronic 
comments will be accepted in Microsoft Word, Excel, WordPerfect, or 
Adobe PDF file formats only.

FOR FURTHER INFORMATION CONTACT: Jolie Harrison, Office of Protected 
Resources, NMFS, (301) 713-2289, ext. 166.

SUPPLEMENTARY INFORMATION:

Availability

    A copy of the Navy's application may be obtained by writing to the 
address specified above (See ADDRESSES), telephoning the contact listed 
above (see FOR FURTHER INFORMATION CONTACT), or visiting the Internet 
at: https://www.nmfs.noaa.gov/pr/permits/incidental.htm. The Navy's 
Draft Environmental Impact Statement (DEIS) for AFAST was published on 
February 15, 2008, and may be viewed at https://www.nmfs.noaa.gov/pr/
permits/incidental.htm. NMFS is participating in the development of the 
Navy's EIS as a cooperating agency under NEPA.

Background

    Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 et seq.) 
direct the Secretary of Commerce (Secretary) to allow, upon request, 
the incidental, but not intentional taking of marine mammals by U.S. 
citizens, who engage in a specified activity (other than commercial 
fishing) during periods of not more than five consecutive years each if 
certain findings are made and regulations are issued or, if the taking 
is limited to harassment, notice of a proposed authorization is 
provided to the public for review.
    Authorization shall be granted if NMFS finds that the taking will 
have a negligible impact on the species or stock(s), will not have an 
unmitigable adverse impact on the availability of the species or 
stock(s) for subsistence uses, and if the permissible methods of taking 
and requirements pertaining to the mitigation, monitoring and reporting 
of such taking are set forth. NMFS has defined ``negligible impact'' in 
50 CFR 216.103 as:

    ``an impact resulting from the specified activity that cannot be 
reasonably expected to, and is not reasonably likely to, adversely 
affect the species or stock through effects on annual rates of 
recruitment or survival.''

    The National Defense Authorization Act of 2004 (NDAA) (Pub. L. 108-
136) removed the ``small numbers'' and ``specified geographical 
region'' limitations and amended the definition of ``harassment'' as it 
applies to a ``military readiness activity'' to read as follows 
(Section 3(18)(B) of the MMPA):

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

Summary of Request

    On February 4, 2008, NMFS received an application from the Navy 
requesting authorization for the take of individuals of 40 species of 
marine mammals incidental to upcoming Navy training activities, 
maintenance, and research, development, testing, and evaluation (RDT&E) 
activities to be conducted within the AFAST Study Area, which extends 
east from the Atlantic Coast of the U.S. to 45[deg] W. long. and south 
from the Atlantic and Gulf of Mexico Coasts to approximately 23[deg] N. 
lat., but not encompassing the Bahamas (see Figure 1-1 in the Navy's 
Application), over the course of 5 years. These training activities are 
classified as military readiness activities. The Navy states, and NMFS 
concurs, that these training activities may incidentally take marine 
mammals present within the AFAST Study Area by exposing them to sound 
from mid-frequency or high frequency active sonar (MFAS/HFAS) or to 
employment of the improved extended echo ranging (IEER) system. The 
IEER consists of an explosive source sonobuoy (AN/SSQ-110A) and an air 
deployable active receiver (ADAR) sonobuoy (AN/SSQ-101). The Navy 
requests authorization to take individuals of 40 species of marine 
mammals by Level B Harassment. Further, though they do not anticipate 
it to occur, the Navy requests authorization to take, by injury or 
mortality, up to 10 beaked whales over the course of the 5-yr 
regulations.

Background of Navy Request

    The purpose of the Navy's proposed action is to provide mid- and 
high-frequency active sonar and IEER system training for U.S. Navy 
Atlantic Fleet ship, submarine, and aircraft crews, as well as to 
conduct RDT&E activities to support the requirements of the Fleet 
Readiness Training Plan (FRTP) and stay proficient in anti-submarine 
warfare (ASW) and mine warfare (MIW) skills. The FRTP is the Navy's 
training cycle that requires naval forces to build up in preparation 
for operational deployment and to maintain a high level of proficiency 
and readiness while deployed. All phases of the FRTP training cycle are 
needed to meet Title 10 requirements.

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    The Navy's need for training and RDT&E is found in Title 10 of the 
United States Code (U.S.C.), Section 5062 (10 U.S.C. 5062). Title 10 
U.S.C. 5062 requires the Navy to be ``organized, trained, and equipped 
primarily for prompt and sustained combat incident to operations at 
sea.'' The current and emerging training and RDT&E activities addressed 
in the AFAST Environmental Impact Statement (EIS)/Overseas 
Environmental Impact Statement (OEIS) are conducted in fulfillment of 
this legal requirement.
    The RDT&E activities addressed in the AFAST EIS/OEIS are those 
RDT&E activities that are substantially similar to training, involving 
existing systems or systems with similar operating parameters.

Description of Specified Activities

Anti-Submarine Warfare (ASW) Training

    The Navy explains that potential adversary nations are investing 
heavily in submarine technology, including designs for nuclear attack 
submarines, strategic ballistic missile submarines, and modern diesel 
electric submarines. In addition, the modern diesel electric submarine 
is the most cost-effective platform for the delivery of several types 
of weapons, including torpedoes, long-range antiship cruise missiles, 
land attack missiles, and a variety of antiship mines. Since submarines 
are inherently covert and can operate independently of escort vessels, 
submarines can be used to conduct intrusive operations in sensitive 
areas and can be inserted early in the mission without being detected. 
The inability to detect a hostile submarine before it can launch a 
missile or a torpedo is a critical vulnerability that puts U.S. forces 
and merchant mariners at risk and, ultimately, threatens U.S. national 
security.
    Because Navy personnel ultimately fight as trained, a training 
environment that matches the conditions of actual combat is necessary. 
Sailors must also train using the combat tools (e.g., active sonar) 
that would be used during a conflict. A complicating factor facing the 
Navy today is the nature of the littoral waters where submarines can 
operate. These littoral regions are frequently confined, congested 
water and air space, which makes identification of allies, adversaries, 
and neutral parties more challenging than in deeper waters. Since an 
adversary equipped with modern, quiet submarines has the potential to 
deny all Department of Defense (DoD) forces access to strategic areas 
of the world, the value of active sonar training has broad effects for 
all DoD forces.

Mine Warfare (MIW) Training

    The use of naval mines is one of the simplest ways for enemies to 
damage ships and disrupt shipping lanes. Over the past 60 years, at 
least 14 U.S. ships, including two in the last decade alone, have been 
damaged or sunk by mines as a result of relatively small-scale mine 
laying operations. Furthermore, since more than 90 percent of military 
equipment used in international operations travels by sea, mines have 
the potential to either delay land and sea military operations by 
denying access to shallow-water areas, or prevent the delivery of 
military equipment altogether.
    Today, the Navy can expect to encounter a wide spectrum of naval 
mines, from traditional, low technology mines, to technologically 
advanced systems. For instance, mines can have irregular shapes, sound-
absorbent coatings, and nonmagnetic material composition, which 
increase their resistance to countermeasures and reduce their 
maintenance requirements. This means that mines can stay active in the 
water longer, are harder to find and are more difficult to neutralize 
(disarm with the use of countermeasures). More advanced mines are 
designed with remote controls, improved sensors, and counter 
countermeasures that further complicate efforts to identify, classify, 
and neutralize them. In addition to improved mine technology, the 
underwater acoustic conditions often present in shallow waters require 
the use of specialized technology to successfully detect, avoid, and 
neutralize mines (DON, 2006a).
    Training on MIW sonar is crucial because mines are a proven and 
cost-effective technology that is continually improving to make them 
more lethal, reliable, and difficult to detect. Because mines do not 
emit sound, active sonar technology, rather than passive, provides the 
warfighter with the capability to quickly and accurately detect, 
classify, and neutralize mines in small, crowded, shallow-water 
environments. These MIW capabilities are essential to ensuring the 
U.S.'s maritime dominance and protecting the Navy's ability to operate 
on both land and sea, including delivery of military equipment.
    As indicated above, the Navy has requested MMPA authorization to 
take marine mammals incidental to training activities in the AFAST 
Study Area that would generate sound in the water at or above levels 
that NMFS has determined will likely result in take (see Acoustic Take 
Criteria Section), either through the use of MFAS/HFAS or the 
employment of the IEER system, which includes explosive sonobuoys. 
Below we discuss the types of sound sources the Navy would utilize and 
the specific exercise types they would use them in.

Acoustic Sources Used for ASW and MIW Exercises in AFAST

    There are two types of sonars, passive and active:
     Passive sonars only listen to incoming sounds and, since 
they do not emit sound energy in the water, lack the potential to 
acoustically affect the environment.
     Active sonars generate and emit acoustic energy 
specifically for the purpose of obtaining information concerning a 
distant object from the received and processed reflected sound energy.
    Modern sonar technology includes a multitude of sonar sensor and 
processing systems. In concept, the simplest active sonars emit omni-
directional pulses (``pings'') and time the arrival of the reflected 
echoes from the target object to determine range. More sophisticated 
active sonar can emit an omni-directional ping and then rapidly scan a 
steered receiving beam to provide directional, as well as range, 
information. Even more advanced sonars transmit multiple preformed 
beams and listen to echoes from several directions simultaneously to 
provide efficient detection of both direction and range.
    The tactical sonars to be deployed during testing and training in 
the AFAST Study Area are designed to detect submarines and mines in 
tactical training scenarios. These tasks require the use of the sonar 
mid-frequency range (1 kilohertz [kHz] to 10 kHz) predominantly, as 
well as a few sources in the high frequency range (above 10 kHz). For 
this document we will refer to the collective high and mid-frequency 
sonar sources as MFAS/HFAS. A narrative description of the types of 
acoustic sources used in ASW and MIW training exercises is included 
below. Table 1 (below) summarizes the nominal characteristics of the 
acoustic sources used in the modeling to predict take of marine mammals 
as well as the estimated annual operation time. Acoustic systems that 
typically operate at frequencies above 200kHz were not analyzed because 
they are outside the upper hearing limits of almost all marine mammals 
and attenuate rapidly due to their extremely high frequencies.
    In addition, systems that were found to have similar acoustic 
output

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parameters (i.e., frequency, power, deflection angles) were compared. 
The system with the largest acoustic footprint was modeled as 
representative of those similar systems that have a smaller acoustic 
footprint. An example of this representative modeling is the AN/AQS-22 
for the AN/AQS-13.
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    Surface Ship Sonars--A variety of surface ships operate the AN/SQS-
53 and AN/SQS-56 hull-mounted MFAS during ASW sonar training exercises, 
currently including 10 guided missile cruisers (CG) (AN/SQS-53), 26 
guided missile destroyers (DDG) (AN/SQS-53), and 18 fast frigates (FFG) 
(AN/SQS 56) on the east coast.
    About half of the U.S. Navy ships do not have any onboard tactical 
sonar systems. Within the AFAST Study Area, these two types of hull-
mounted sonar sources account for the majority of the estimated impacts 
to marine mammals. The AN/SQS-53 hull-mounted sonar, which has a 
nominal source level of 235 decibels (dB) re 1 [mu]Pa and transmits at 
a center frequency 3.5 kHz, is the Navy's most powerful sonar source 
used in ASW exercises in the AFAST Study Area.
    Hull-mounted sonars occasionally operate in a mode called 
``Kingfisher'', which is designed to better detect smaller objects. The 
Kingfisher mode uses the same source level and frequency as normal 
search modes, however, it uses a different waveform (designed for small 
objects), a shorter pulse length (< 1 sec), a higher pulse repetition 
rate (due to the short ranges),

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and the ping is not omnidirectional, but directed forward.
    Submarine Sonars--Tactical submarines (i.e., 29 nuclear powered 
attack submarines (SSN) on the east coast) equipped with BQQ-5 or BQQ-
10 hull-mounted MFA sonars, are used to detect and target enemy 
submarines and surface ships. A submarine's mission revolves around its 
stealth; therefore, MFAS are used very infrequently since the pinging 
of the MFAS also identifies the location of the submarine. Note that 
the BQQ-10 is the more predominant system, and that the system is 
identified throughout the remainder of this document with the 
understanding that the BQQ-5 and BQQ-10 are similar in those 
operational parameters with a potential to affect marine mammals. In 
addition, Seawolf Class attack submarines, Virginia Class attack 
submarines, Los Angeles Class attack submarines, and Ohio Class nuclear 
guided missile submarines also have the AN/BQS-15, a sonar that uses 
both mid- and high-frequency for under-ice navigation and mine-hunting.
    Aircraft Sonar Systems--Aircraft sonar systems that would operate 
in the AFAST Study Area include sonobuoys (AN/SSQ-62 and AN/SSQ-110A) 
and dipping sonar (AN/AQS-13 or AN/AQS-22).
     Sonobuoys, deployed by both helicopter and fixed-wing 
Maritime Patrol aircraft (MPA), are expendable devices that are either 
tonal (active), impulsive (explosive), or listening (passive). The Navy 
uses a tonal sonobuoy called a Directional Command-Activated sonobuoy 
System (DICASS AN/SQQ-62) and a sonobuoy system called an IEER system, 
which consists of an explosive source sonobuoy (AN/SSQ-110A) and a 
passive receiver sonobuoy (AN/SSQ-101). The Navy also uses a passive 
sonobuoy called a Directional Frequency Analysis and Recording (DIFAR). 
Passive listening sonobuoys such as DIFAR (AN/SSQ-53) are deployed from 
helicopters or maritime patrol aircraft and do not emit active sonar. 
These systems are used for the detection and tracking of submarine 
threats.
     Dipping active/passive sonars, present on helicopters, are 
recoverable devices that are lowered via a cable to detect or maintain 
contact with underwater targets. The Navy uses the AN/AQS-13 and AN/
AQS-22 dipping sonars. Helicopters can be based ashore or aboard a 
ship.
    Torpedoes--Torpedoes are the primary ASW weapons used by surface 
ships, aircraft, and submarines. The guidance systems of these weapons 
can be autonomous or electronically controlled from the launching 
platform through an attached wire. The autonomous guidance systems are 
acoustically based. They operate either passively by listening for 
sound generated by the target, or actively by pinging the target and 
using the echoes for guidance. All torpedoes to be used during ASW 
activities are recoverable and nonexplosive. The majority of torpedo 
firings occurring during AFAST activities are air slugs (dry fire) or 
shapes (i.e., solid masses resembling the weight and shape of a 
torpedo).
    Acoustic Device Countermeasures (ADC)--Several types of 
countermeasure devices could be deployed during Fleet training 
exercises, including the Acoustic Device Countermeasure MK-1, MK-2, MK-
3, MK-4, and the AN/SLQ-25A (NIXIE). Countermeasure devices act as 
decoys to avert localization and torpedo attacks. Countermeasures may 
be towed or free floating sources.
    Training Targets--ASW training targets are used to simulate target 
submarines. They are equipped with one or more of the following 
devices: (1) Acoustic projectors emanating sounds to simulate submarine 
acoustic signatures, (2) echo repeaters to simulate the characteristics 
of the echo of a particular sonar signal reflected from a specific type 
of submarine, and (3) magnetic sources to trigger magnetic detectors. 
The Navy uses the Expendable Mobile Acoustic Training Target (EMATT) 
and the MK-30 acoustic training targets (recovered) during ASW sonar 
training exercises.

Types of ASW and MIW Exercises in the AFAST Study Area

    ASW and MIW training is conducted to meet deployment certification 
requirements as directed in the FRTP. The U.S. Navy Atlantic Fleet 
meets these requirements by conducting training activities prior to 
deployment of forces. The FRTP requires Basic Unit Level Training 
(ULT), Intermediate, and Sustainment Training. The Navy meets these 
requirements during Independent ULT, Coordinated ULT, and Strike Group 
Training. At the beginning of the cycle, basic combat skills are 
learned and practiced during basic Independent ULT activities, which 
include training and sonar maintenance activities that each individual 
unit is required to accomplish in order to become certified prior to 
deploying or to maintain proficiency. Basic skills are then refined 
during Coordinated ULT activities, which concentrate on warfare team 
training and initial multiunit operations. During this phase, vessels 
and aircraft begin to develop warfare skills in coordination with other 
units while continuing to maintain unit proficiency. Strike Group 
Training continues to develop and refine warfare skills and command and 
control procedures using progressively more difficult, complex, and 
large scale exercises conducted at an increasing tempo. This training 
provides the warfighter with the skills necessary to function as part 
of a coordinated fighting force in a hostile environment with the 
capacity to accomplish multiple missions.
    Additionally, RDT&E activities are conducted to develop new 
technologies and to ensure their effectiveness prior to implementation. 
Maintenance activities are conducted pier side and during transit to 
training exercise locations. Active sonar maintenance is required to 
ensure the sonar system is operating properly before engaging in the 
training exercise or when the sonar systems are suspected of performing 
below optimal levels.
    Because the Navy conducts many different types of Independent ULT, 
Coordinated ULT, Strike Group training, maintenance, and RDT&E active 
sonar events, the Navy grouped similar events to form representative 
scenarios. Note that specific training event names and other details do 
occasionally change as required to meet the current operational needs. 
Table 2 lists the types of ASW, MIW, and maintenance exercises and 
indicates: The nature of the exercise, the areas the exercises are 
conducted in and the area they span, the average duration of an 
exercise, the average number of exercises/per year, and the sound 
sources that are used in the exercises.
    Table 1 indicates the total number of hours for each source type 
anticipated for each year for each exercise type.
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    The Navy's AFAST EIS and LOA application were designed specifically 
to cover active sonar training because the need for operational 
flexibility, a variety of training scenarios, as well as proximity to 
multiple ports, airfields, and bases along the eastern seaboard in 
these exercises has long necessitated that the exercises be conducted 
outside of the boundaries of any one Operating Areas (OPAREA). 
Alternately, exercises utilizing explosive detonations are typically 
conducted within a particular OPAREA, and as such are being addressed 
separately within EISs and LOA requests for the various applicable 
OPAREAs. With the exception of the Extended Echo Ranging and Improved 
Extended Echo Ranging (IEER) system, the AFAST proposed authorization 
does not contain any explosive sources, only MFAS and HFAS. The IEER is 
included in AFAST because it is most often used in ASW exercises. The 
IEER Systems are air-launched ASW systems used in conducting ``large 
area'' searches for submarines. These systems are made up of airborne 
avionics ASW acoustic processing and sonobuoy types that are deployed 
in pairs. The IEER System's active sonobuoy component, the AN/SSQ-110A 
Sonobuoy, would generate a ``ping'' (small detonation, as opposed to a 
sonar signal) and the passive AN/SSQ-101 ADAR Sonobuoy would ``listen'' 
for the return echo of the ping that has been bounced off the surface 
of a submarine. These sonobuoys are designed to provide underwater 
acoustic data necessary for naval aircrews to quickly and accurately 
detect submerged submarines. The expendable and commandable sonobuoy 
pairs are dropped from a fixed-wing aircraft into the ocean in a 
predetermined pattern (array) with a few buoys covering a very large 
area. Upon command from the aircraft, the bottom payload is released to 
sink to a designated operating depth. A second command is required from 
the aircraft to cause the second payload to release and detonate 
generating a ``ping''. There is only one detonation in the pattern of 
buoys at a time.
    Additional information on the Navy's proposed activities may be 
found in the LOA Application and the Navy's AFAST DEIS.

AFAST Study Area

    Figure 1-1 in the Navy's application, which may be viewed at: 
https://www.nmfs.noaa.gov/pr/permits/incidental.htm, depicts the AFAST 
Study Area, which extends east from the Atlantic Coast of the U.S. to 
45[deg] W. long. and south from the Atlantic and Gulf of Mexico Coasts 
to approximately 23[deg] N. lat., but not encompassing the Bahamas (see 
Figure 1-1 in the Navy's Application). The Navy's Atlantic Fleet trains 
in a series of OPAREAs along the U.S. East Coast and in the Gulf of 
Mexico. Due to the size of the battle space needed for effective 
conduct of activities, training and testing also occur seaward of these 
OPAREAs. The OPAREAs include the Northeast OPAREA, the Virginia Capes 
(VACAPES) OPAREA, the Cherry Point (CHPT) OPAREA, the Jacksonville/
Charleston (JAX/CHASN) OPAREA, and the Gulf of Mexico (GOMEX) OPAREA. 
The locations of the OPAREAs and the shoreward/seaward boundary of the 
Study Area are depicted in Figure 1-1 of the Navy's application. Note 
that the Northeast and Gulf of Mexico OPAREAs encompass a series of 
OPAREAs. The Northeast OPAREA includes the Boston, Atlantic City, and 
Narragansett Bay OPAREAs. The GOMEX OPAREAs includes the Pensacola, 
Panama City, Corpus Christi, New Orleans, and Key West OPAREAs. For the 
purposes of this document, an OPAREA includes the existing OPAREA, as 
well as adjacent shoreward and seaward areas. Table 3 summarizes the 
typical number of events per year by OPAREA.

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    For the purposes of the proposed action that is the subject of this 
Letter of Authorization (LOA) request, active sonar activities would 
occur year-round throughout the Study Area. Active sonar activities 
would occur in locations that maximize active sonar opportunities and 
meet applicable operational requirements associated with a specific 
active sonar activity. Below we provide additional detail (beyond 
Tables 2 and 3), where available (i.e., the advance detail is available 
and the information is not classified), regarding where certain active 
sonar training, research, development, test, and evaluation (RDT&E), 
and maintenance activities would occur.
ASW Training Areas
    ASW activities for all platforms could occur within and adjacent to 
existing East Coast OPAREAS beyond 22.2 km (12 NM) with the exception 
of sonar dipping activities. However, most ASW training involving 
submarines or submarine targets would occur in waters greater than 183 
m (600 ft) deep due to safety concerns about running aground at 
shallower depths. ASW active sonar activities occurring in specific 
locations are discussed below.
    Helicopter ASW ULT Areas--This activity would be conducted in the 
waters of the East Coast OPAREAs typically near fleet concentration 
areas while embarked on a surface ship. Helicopter ASW ULT events are 
also conducted by helicopters deployed from shore-based Jacksonville, 
Florida, units. These helicopter units use established sonar dipping 
areas offshore Mayport (Jacksonville), Florida, which are located in 
territorial waters and within the southeast North Atlantic right whale 
(NARW) critical habitat. This is the only area where helicopter ASW ULT 
could occur within 22 km (12 NM) of shore.
    Southeastern Anti-Submarine Warfare Integrated Training (SEASWITI) 
Areas--This training exercise generally occurs in deep water off the 
coast of Jacksonville, Florida.
    Group Sail Areas--These events typically take place within and 
seaward of the VACAPES, CHPT, and JAX/CHASN OPAREAs.
    Submarine Command Course (SCC) Operations Areas--This training 
exercise typically occurs in the JAX/CHASN and Northeast OPAREAs in 
deep ocean areas.
    Strike Group Training Areas--These events typically take place 
within and seaward of the VACAPES, CHPT, and JAX/CHASN OPAREAs, 
although an event could occasionally be conducted in the GOMEX OPAREA.
    Torpedo Exercise (TORPEX) Areas--TORPEXs can occur anywhere within 
and adjacent to East Coast and GOMEX OPAREAs. The exception is in the 
Northeast OPAREA where the North Atlantic right whale critical habitat 
is located. TORPEX areas that meet current operational requirements for 
proximity to torpedo and target recovery

[[Page 60764]]

support facilities in the Northeast were established during previous 
consultations. Therefore, TORPEX activities in the northeast North 
Atlantic right whale critical habitat are limited to these established 
areas. Most torpedo activities would occur near torpedo recovery 
support facilities in the Northeast or GOMEX OPAREAs.
MIW Training Areas
    MIW Training could occur in territorial or non-territorial waters. 
Independent and Coordinated MIW ULT activities would be conducted 
within and adjacent to the Pensacola and Panama City OPAREAs in the 
northern Gulf of Mexico and off the east coast of Texas in the Corpus 
Christi OPAREA. The Squadron Exercise (RONEX) or GOMEX Exercise would 
be conducted in both deep and shallow water training areas.
    Object Detection/Navigational Training Areas--Surface Ship training 
would be conducted primarily in the shallow water port entrance and 
exit lanes for Norfolk, Virginia, and Mayport, Florida. The transit 
lane servicing Mayport, Florida crosses through the southeast North 
Atlantic right whale critical habitat. Submarine training would occur 
primarily in the established submarine transit lanes entering/exiting 
Groton, Connecticut; Norfolk, Virginia; and Kings Bay, Georgia. The 
transit lane servicing Kings Bay, Georgia crosses through the southeast 
North Atlantic right whale critical habitat.

Maintenance Areas

    Maintenance activities could occur in homeports located in 
territorial waters, or in the open ocean during transit in non-
territorial waters.

RDT&E Areas

    For RDT&E activities included in this analysis, active sonar 
activities occur in similar locations as representative training 
events.

National Marine Sanctuaries

    At present, the Navy does not conduct active sonar activities in 
the Stellwagen Bank, USS Monitor, Gray's Reef, Flower Garden Banks, and 
Florida Keys National Marine Sanctuaries. The Navy would, as 
appropriate, comply with the National Marine Sanctuaries Act and any 
applicable regulations if it is determined that an active sonar 
activity may occur in or near these sanctuaries, and would ensure that 
naval activities be carried out in a manner that avoids to the maximum 
extent practicable any adverse impacts on sanctuary resources and 
qualities. Although activities in the Sanctuaries are not planned or 
anticipated, NMFS' analysis, for purposes of the MMPA considers the 
effects on marine mammals of the Navy's conducting activities in the 
biologically important areas that occur in or near Sanctuaries.

North Atlantic Right Whale (NARW) Critical Habitat

    NMFS designated three areas in June 1994 as critical habitat for 
the western North Atlantic population of the North Atlantic right 
whale. They include the following:
    1. Coastal Florida and Georgia (Sebastian Inlet, FL to the Altamaha 
River, GA),
    2. Great South Channel (east of Cape Cod), and
    3. Massachusetts Bay and Cape Cod Bay.
    The Navy proposes to conduct two types of activities in the NARW 
critical habitat. Approximately 84 of the 115 helicopter dipping sonar 
exercises (2-4 hours each) conducted annually in the CHASN/JAX OPAREA 
would occur in the designated near-shore training area, which fans out 
approximately 10 miles from Mayport. Part of the near-shore shore 
training area overlaps the NARW critical habitat. However, 
historically, only maintenance of helicopter dipping sonars occured 
(approximately 30 events) in the portion of the training area that 
overlaps with NARW critical habitat. Tactical training with helicopter 
dipping sonar does not typically occur in the NARW critical habitat 
area at any time of the year. The critical habitat area is used on 
occasion for post maintenance operational checks and equipment testing 
due to its proximity to shore. In addition, the Navy would conduct 
approximately 40 ship object detection/navigational sonar training 
exercises (1-2 hours each) and 57 submarine object detection/
navigational sonar training exercises (1-2 hours each) annually while 
entering/exiting port at Mayport, FL and Kings Bay, GA, respectively 
(within approximately 1 mile of the shore). These two activities could 
occur year round. No other active sonar activities would occur in the 
southeast critical habitat.
    In the northeastern critical habitat, the Navy would conduct TORPEX 
activities. These activities would be conducted in August, September, 
and October as prescribed in a prior Endangered Species Act (ESA) 
Section 7 consultation with NMFS. Water depths in this area are less 
than the optimal depth for most ASW activities.
    In summary, currently active sonar training does not occur in North 
Atlantic right whale critical habitat with the exception of object 
detection and navigation off shore Mayport, Florida and Kings Bay, 
Georgia; helicopter Anti-Submarine Warfare (ASW) offshore Mayport, 
Florida; and torpedo exercises (TORPEXs) in the northeast critical 
habitat during August, September, and October.

Description of Marine Mammals in the Area of the Specified Activities

    There are 43 marine mammal species with possible or confirmed 
occurrence in the AFAST Study Area. As indicated in Table 4, there are 
36 cetacean species (7 mysticetes and 29 odontocetes), six pinnipeds, 
and one sirenian (manatee). Six marine mammal species listed as 
federally endangered under the Endangered Species Act (ESA) and under 
the jurisdiction of NMFS occur in the AFAST Study Area: The North 
Atlantic right whale, humpback whale, sei whale, fin whale, blue whale, 
and sperm whale. Manatees are managed by the U.S. Fish and Wildlife 
Service and will not be addressed further here.
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    The Navy has compiled information on the abundance, behavior, 
status and distribution, and vocalizations of marine mammal species in 
the AFAST Study Area waters from peer reviewed literature, the Navy 
Marine Resource Assessments, NMFS Stock Assessment Reports, and marine 
mammal surveys using acoustics or visual observations from aircraft or 
ships. This information may be viewed in the Navy's LOA application 
and/or the Navy's EIS for AFAST (see Availability). Additional 
information is available in NMFS Stock Assessment Reports, which may be 
viewed at: https://www.nmfs.noaa.gov/pr/sars/species.htm.
    Neither the beluga whale nor ringed seals have stocks designated in 
the Northwest Atlantic Ocean or the Gulf of Mexico. The St. Lawrence 
estuary is at the southern limit of the distribution of the beluga 
whale (Lesage and Kingsley, 1998). Beluga distribution does not include 
the Gulf of Mexico or the southeastern Atlantic Coast and they are 
considered extralimital in the Northeast. The ringed seal has a 
circumpolar distribution throughout the Arctic Ocean, Hudson Bay, and 
Baltic and Bering seas (Reeves et al., 2002b) and is expected only as 
far south as Newfoundland (Frost and Lowry, 1981). Based on their rare 
occurrence in the AFAST study area, the Navy and NMFS do not anticipate 
any take of ringed seals or beluga whales, and, therefore, they are not 
addressed further in this document.

Important Areas

    Because the consideration of areas where marine mammals are known 
to selectively breed or calve/pup are important to both the negligible 
impact finding necessary for the issuance of an MMPA authorization and 
the need for NMFS to put forth the means of effecting the least 
practicable adverse impact paying particular attention to rookeries, 
mating grounds, and other areas of similar significance, we are 
emphasizing known important reproductive and feeding areas within this 
section.
    Little is known about the breeding and calving behaviors of many of 
the marine mammals that occur in the AFAST Study Area. For rorquals 
(humpback whale, minke whale, Bryde's whale, sei whale, fin whale, and 
blue whale) and sperm whales, mating is generally thought to occur in 
tropical and sub-tropical waters between mid-winter and mid-summer in 
deep off-shore waters. Delphinids (Melon-headed Whale, Killer Whale, 
Pygmy Killer Whale, False Killer Whale, Pilot Whale, Common Dolphin, 
Atlantic Spotted Dolphin, Clymene Dolphin, Pantropical Spotted Dolphin, 
Spinner Dolphin, Striped Dolphin, Rough-toothed Dolphin, Common 
Bottlenose Dolphin, Risso's Dolphin, Fraser's Dolphin, Atlantic White-
sided Dolphin, White-beaked Dolphin) may mate within any area of their 
distribution throughout the year. For pinnipeds, mating and pupping 
typically occurs in coastal waters near northeast rookeries. With one 
notable exception, no specific breeding or calving/pupping areas have 
been identified in the AFAST Study Area for the species that occur 
there. However, critical habitat has been designated, pursuant to the 
Endangered Species Act (ESA), for the North Atlantic right whale.

North Atlantic Right Whale

    Most North Atlantic right whale sightings follow a well-defined 
seasonal migratory pattern through several consistently utilized 
habitats (Winn et al., 1986). It should be noted, however, that some 
individuals may be sighted in these habitats outside the typical time 
of year and that migration routes are poorly known (there may be a 
regular offshore component). The population migrates as two separate 
components, although some whales may remain in the feeding grounds 
throughout the winter (Winn et al., 1986; Kenney et al., 2001). 
Pregnant females and some juveniles migrate from the feeding grounds to 
the calving grounds off the southeastern United States in late fall to 
winter. The cow-calf pairs return northward in late winter to early 
spring. The majority of the right whale population leaves the feeding 
grounds for unknown habitats in the winter but returns to the feeding 
grounds coinciding with the return of the cow-calf pairs. Some 
individuals as well as cow-calf pairs can be seen through the fall and 
winter on the feeding grounds with feeding being observed (e.g., Sardi 
et al., 2005).
    During the spring through early summer, North Atlantic right whales 
are found on feeding grounds off the northeastern United States and 
Canada. Individuals may be found in Cape Cod Bay in February through 
April (Winn et al., 1986; Hamilton and Mayo, 1990) and in the Great 
South Channel east of Cape Cod in April through June (Winn et al., 
1986; Kenney et al., 1995). Right whales are found throughout the 
remainder of summer and into fall (June through November) on two 
feeding grounds in Canadian waters (Gaskin, 1987 and 1991), with peak 
abundance in August, September, and early October. The majority of 
summer/fall sightings of mother/calf pairs occur east of Grand Manan 
Island (Bay of Fundy), although some pairs might move to other unknown 
locations (Schaeff et al., 1993). Jeffreys Ledge appears to be 
important habitat for right whales, with extended whale residences; 
this area appears to be an important fall feeding area for right whales 
and an important nursery area during summer (Weinrich et al., 2000). 
The second feeding area is off the southern tip of Nova Scotia in the 
Roseway Basin between Browns, Baccaro, and Roseway banks (Mitchell et 
al., 1986; Gaskin, 1987; Stone et al., 1988; Gaskin, 1991). The Cape 
Cod Bay and Great South Channel feeding grounds are formally designated 
as critical habitats under the ESA (Silber and Clapham, 2001).
    During the winter (as early as November and through March), North 
Atlantic right whales may be found in coastal waters off North 
Carolina, Georgia, and northern Florida (Winn et al., 1986). The waters 
off Georgia and northern Florida are the only known calving ground for 
western North Atlantic right whales; it is formally designated as a 
critical habitat under the ESA. Calving occurs from December through 
March (Silber and Clapham, 2001). On 1 January 2005, the first observed 
birth on the calving grounds was reported (Zani et al., 2005). The 
majority of the population is not accounted for on the calving grounds, 
and not all reproductively active females return to this area each year 
(Kraus et al., 1986a).
    The coastal waters of the Carolinas are suggested to be a migratory 
corridor for the right whale (Winn et al., 1986). The Southeast U.S. 
Coast Ground, consisting of coastal waters between North Carolina and 
northern Florida, was mainly a winter and early spring (January-March) 
right whaling ground during the late 1800s (Reeves and Mitchell, 1986). 
The whaling ground was centered along the coasts of South Carolina and 
Georgia (Reeves and Mitchell, 1986). An examination of sighting records 
from all sources between 1950 and 1992 found that wintering right 
whales were observed widely along the coast from Cape Hatteras, North 
Carolina, to Miami, Florida (Kraus et al., 1993). Sightings off the 
Carolinas were comprised of single individuals that appeared to be 
transients (Kraus et al., 1993). These observations are consistent with 
the hypothesis that the coastal waters of the Carolinas are part of a 
migratory corridor for the right whale (Winn et al., 1986). Knowlton et 
al. (2002) analyzed sightings data collected in the mid-Atlantic from 
northern Georgia to southern New England and found that

[[Page 60767]]

the majority of right whale sightings occurred within approximately 56 
km (30 NM) from shore. Until better information is available on the 
right whale's migratory corridor, it has been recommended that 
management considerations are needed for the coastal areas along the 
mid-Atlantic migratory corridor within 65 km (35 NM) from shore 
(Knowlton, 1997).
    Critical habitat for the North Atlantic population of the North 
Atlantic right whale exists in portions of the JAX/CHASN and Northeast 
OPAREAs (Figures 4-1 and 4-2 of the Navy's Application). The following 
three areas occur in U.S. waters and were designated by NMFS as 
critical habitat in June 1994 (NMFS, 2005):
     Coastal Florida and Georgia (Sebastian Inlet, Florida, to 
the Altamaha River, Georgia),
     The Great South Channel, east of Cape Cod, and
     Cape Cod and Massachusetts Bays.
    The northern critical habitat areas serve as feeding and nursery 
grounds, while the southern area from the mid-Georgia coast extending 
southward along Florida serves as calving grounds. The waters off 
Georgia and northern Florida are the only known calving ground for 
western North Atlantic right whales. A large portion of this habitat 
lies within the coastal waters of the JAX/CHASN OPAREA. The physical 
features correlated with the distribution of right whales in the 
southern critical habitat area provide an optimum environment for 
calving. For example, the bathymetry of the inner and nearshore middle 
shelf area minimizes the effect of strong winds and offshore waves, 
limiting the formation of large waves and rough water. The average 
temperature of critical habitat waters is cooler during the time right 
whales are present due to a lack of influence by the Gulf Stream and 
cool freshwater runoff from coastal areas. The water temperatures may 
provide an optimal balance between offshore waters that are too warm 
for nursing mothers to tolerate, yet not too cool for calves that may 
only have minimal fatty insulation. On the calving grounds, the 
reproductive females and calves are expected to be concentrated near 
the critical habitat in the JAX/CHASN OPAREA from December through 
April.

Humpback Whale

    In the North Atlantic Ocean, humpbacks are found from spring 
through fall on feeding grounds that are located from south of New 
England to northern Norway (NMFS, 1991). The Gulf of Maine is one of 
the principal summer feeding grounds for humpback whales in the North 
Atlantic. The largest numbers of humpback whales are present from mid-
April to mid-November. Feeding locations off the northeastern United 
States include Stellwagen Bank, Jeffreys Ledge, the Great South 
Channel, the edges and shoals of Georges Bank, Cashes Ledge, Grand 
Manan Banks, the banks on the Scotian Shelf, the Gulf of St. Lawrence, 
and the Newfoundland Grand Banks (CETAP, 1982; Whitehead, 1982; Kenney 
and Winn, 1986; Weinrich et al., 1997). Distribution in this region has 
been largely correlated to prey species and abundance, although 
behavior and bottom topography are factors in foraging strategy (Payne 
et al., 1986; Payne et al., 1990b). Humpbacks typically return to the 
same feeding areas each year. Feeding most often occurs in relatively 
shallow waters over the inner continental shelf and sometimes in deeper 
waters. Large multi-species feeding aggregations (including humpback 
whales) have been observed over the shelf break on the southern edge of 
Georges Bank (CETAP, 1982; Kenney and Winn, 1987) and in shelf break 
waters off the U.S. mid-Atlantic coast (Smith et al., 1996).

Sperm Whale

    The region of the Mississippi River Delta (Desoto Canyon) has been 
recognized for high densities of sperm whales and appears to represent 
an important calving and nursery area for these animals (Townsend, 
1935; Collum and Fritts, 1985; Mullin et al., 1994a; Wursig et al., 
2000; Baumgartner et al., 2001; Davis et al., 2002; Mullin et al., 
2004; Jochens et al., 2006). Sperm whales typically exhibit a strong 
affinity for deep waters beyond the continental shelf, though in the 
area of the Mississippi Delta they also occur on the outer continental 
shelf break.

Marine Mammal Density Estimates

    Density estimates for cetaceans were either modeled for each region 
(Northeast, Southeast, and GOMEX) using available line-transect survey 
data or derived in order of preference: (1) Through spatial models 
using line-transect survey data provided by NMFS; (2) using abundance 
estimates from Mullin and Fulling (2003), Fulling et al. (2003), and/or 
Mullin and Fulling (2004); (3) or based on the cetacean abundance 
estimates found in the most current NOAA stock assessment report (SAR) 
(Waring et al., 2007). The Navy derived the densities the following way 
for each area:
     Northeast OPAREAs: The traditional line-transect methods 
used in the preliminary Northeast NODE (DON, 2006c) and abundance 
estimates from the North Atlantic Right Whale Consortium (NARWC, 2006). 
Density estimates for pinnipeds in these OPAREAs were derived from 
abundance estimates found in the NOAA stock assessment report (Waring 
et al., 2007) or from the scientific literature (Barlas, 1999).
     Southeast OPAREAs: Abundance estimates found in the NOAA 
stock assessment report (Waring et al., 2007) or in Mullin and Fulling 
(2003).
     Gulf of Mexico OPAREAs: Abundance estimates found in the 
NOAA stock assessment report (Waring et al., 2007) based on Mullin and 
Fulling (2004).
    Using the indicated data, the Navy was able to estimate densities 
for most species, by OPAREA (and sometimes in greater detail--like for 
the area around Mayport) and by season.
    The detailed density estimate methods and results may be viewed in 
the Navy OPAREA Density Estimates (NODE) for the Northeast OPAREAS 
report (DON, 2007e), the NODE for the Southeast OPAREAS report (DON, 
2007f), and the NODE for the GOMEX OPAREA report (DON, 2007g), which 
are available at: https://www.nmfs.noaa.gov/pr/permits/incidental.htm. 
NMFS has also posted a summary of the density estimates on our Web 
site: https://www.nmfs.noaa.gov/pr/permits/incidental.htm.

Brief Background on Sound

    An understanding of the basic properties of underwater sound is 
necessary to comprehend many of the concepts and analyses presented in 
this document. A summary is included below.
    Sound is a wave of pressure variations propagating through a medium 
(for the sonar considered in this proposed rule, the medium is marine 
water). Pressure variations are created by compressing and relaxing the 
medium. Sound measurements can be expressed in two forms: intensity and 
pressure. Acoustic intensity is the average rate of energy transmitted 
through a unit area in a specified direction and is expressed in watts 
per square meter (W/m\2\). Acoustic intensity is rarely measured 
directly, it is derived from ratios of pressures; the standard 
reference pressure for underwater sound is 1 microPascal ([mu]Pa); for 
airborne sound, the standard reference pressure is 20 [mu]Pa 
(Richardson et al., 1995).
    Acousticians have adopted a logarithmic scale for sound 
intensities, which is denoted in decibels (dB). Decibel measurements 
represent the ratio between a measured pressure value

[[Page 60768]]

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

Metrics Used in This Document

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

SPL

    Sound pressure is the sound force per unit area, and is usually 
measured in micropascals ([mu]Pa), where 1 Pa is the pressure resulting 
from a force of one newton exerted over an area of one square meter. 
SPL is expressed as the ratio of a measured sound pressure and a 
reference level. The commonly used reference pressure level in 
underwater acoustics is 1 [mu]Pa, and the units for SPLs are dB re: 1 
[mu]Pa.
    SPL (in dB) = 20 log (pressure / reference pressure)
    SPL is an instantaneous measurement and can be expressed as the 
peak, the peak-peak, or the root mean square (rms). Root mean square, 
which is the square root of the arithmetic average of the squared 
instantaneous pressure values, is typically used in discussions of the 
effects of sounds on vertebrates and all references to SPL in this 
document refer to the root mean square. SPL does not take the duration 
of a sound into account. SPL is the applicable metric used in the risk 
continuum, which is used to estimate behavioral harassment takes (see 
Level B Harassment Risk Function (Behavioral Harassment) Section).

SEL

    SEL is an energy metric that integrates the squared instantaneous 
sound pressure over a stated time interval. The units for SEL are dB 
re: 1 [mu]Pa\2\-s.

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    SEL = SPL + 10 log (duration in seconds)
    As applied to tactical sonar, the SEL includes both the SPL of a 
sonar ping and the total duration. Longer duration pings and/or pings 
with higher SPLs will have a higher SEL. If an animal is exposed to 
multiple pings, the SEL in each individual ping is summed to calculate 
the total SEL. The total SEL depends on the SPL, duration, and number 
of pings received. The thresholds that NMFS uses to indicate at what 
received level the onset of temporary threshold shift (TTS) and 
permanent threshold shift (PTS) in hearing are likely to occur are 
expressed in SEL.

Potential Effects of Specified Activities on Marine Mammals

Exposure to MFAS/HFAS

    The Navy has requested authorization for the take of marine mammals 
that may occur incidental to training activities in the AFAST Study 
Area utilizing MFAS/HFAS or the IEER system, which includes an 
explosive sonobuoy. The Navy has analyzed the potential impacts to 
marine mammals from AFAST, including ship strike, entanglement in or 
direct strike by expended materials, ship noise, and others, and in 
consultation with NMFS as a cooperating agency for the AFAST EIS, has 
determined that take of marine mammals incidental to these non-acoustic 
components of AFAST is unlikely (see the Navy's LOA application and 
March addendum to the application) and, therefore, has not requested 
authorization for take of marine mammals that might occur incidental to 
these non-acoustic components. In this document, NMFS analyzes the 
potential effects on marine mammals from exposure to MFAS/HFAS and 
underwater detonations from the IEER.
    For the purpose of MMPA authorizations, NMFS' effects assessments 
serve three primary purposes: (1) To put forth the permissible methods 
of taking within the context of MMPA Level B Harassment (behavioral 
harassment), Level A Harassment (injury), and mortality (i.e., identify 
the number and types of take that will occur); (2) to determine whether 
the specified activity will have a negligible impact on the affected 
species or stocks of marine mammals (based on the likelihood that the 
activity will adversely affect the species or stock through effects on 
annual rates of recruitment or survival); and (3) to determine whether 
the specified activity will have an unmitigable adverse impact on the 
availability of the species or stock(s) for subsistence uses (however, 
there are no subsistence communities that would be affected in the 
AFAST Study Area, so this determination is inapplicable for AFAST).
    More specifically, for activities involving active tactical sonar 
or underwater detonations, NMFS' analysis will identify the probability 
of lethal responses, physical trauma, sensory impairment (permanent and 
temporary threshold shifts and acoustic masking), physiological 
responses (particular stress responses), behavioral disturbance (that 
rises to the level of harassment), and social responses that would be 
classified as behavioral harassment or injury and/or would be likely to 
adversely affect the species or stock through effects on annual rates 
of recruitment or survival. In this section, we will focus 
qualitatively on the different ways that MFAS/HFAS and underwater 
explosive detonations (IEER) may affect marine mammals (some of which 
NMFS would not classify as harassment). Then, in the Estimated Take of 
Marine Mammals Section, NMFS will relate the potential effects to 
marine mammals from MFAS/HFAS and underwater detonation of explosives 
to the MMPA regulatory definitions of Level A and Level B Harassment 
and attempt to quantify those effects.
    In its April 14, 2008, Biological Opinion of the U.S. Navy's 
proposal to conduct four training exercises in the Cherry Point, 
Virginia Capes, and Jacksonville Range Complexes NMFS presented a 
conceptual model of the potential responses of endangered and 
threatened species upon being exposed to active sonar and the pathways 
by which those responses might affect the fitness of individual animals 
that have been exposed, which may then affect the reproduction and/or 
survival of those individuals. Literature supporting the framework, 
with examples drawn from many taxa (both aquatic and terrestrial) was 
included in the ``Application of this Approach'' and ``Response 
Analyses'' sections of that document (available at: https://
www.nmfs.noaa.gov/pr/permits/incidental.htm). This conceptual framework 
may also be used to describe the responses and pathways for non-
endangered and non-threatened species and is included in the Biological 
Opinion of the U.S. Navy's proposal to conduct four training exercises 
in the Cherry Point, Virginia Capes, and Jacksonville Range Complexes.

Direct Physiological Effects

    Based on the literature, there are two basic ways that MFAS/HFAS 
might directly result in physical trauma or damage: noise-induced loss 
of hearing sensitivity (more commonly-called ``threshold shift'') and 
acoustically mediated bubble growth. Separately, an animal's behavioral 
reaction to an acoustic exposure might lead to physiological effects 
that might ultimately lead to injury or death, which is discussed later 
in the Stranding section.

Threshold Shift (Noise-Induced Loss of Hearing)

    When animals exhibit reduced hearing sensitivity (i.e., sounds must 
be louder for an animal to recognize them) following exposure to a 
sufficiently intense sound, it is referred to as a noise-induced 
threshold shift (TS). An animal can experience temporary threshold 
shift (TTS) or permanent threshold shift (PTS). TTS can last from 
minutes or hours to days (i.e., there is recovery), occurs in specific 
frequency ranges (i.e., an animal might only have a temporary loss of 
hearing sensitivity between the frequencies of 1 and 10 kHz), and can 
be of varying amounts (for example, an animal's hearing sensitivity 
might be reduced by only 6 dB or reduced by 30 dB). PTS is permanent 
(i.e., there is no recovery), but also occurs in a specific frequency 
range and amount as mentioned above for TTS.
    The following physiological mechanisms are thought to play a role 
in inducing auditory TSs: Effects to sensory hair cells in the inner 
ear that reduce their sensitivity, modification of the chemical 
environment within the sensory cells, residual muscular activity in the 
middle ear, displacement of certain inner ear membranes, increased 
blood f