Taking and Importing Marine Mammals; Taking Marine Mammals Incidental to Conducting the Precision Strike Weapon (PSW) Testing and Training by Eglin Air Force Base in the Gulf of Mexico, 48675-48691 [05-16390]

Agencies

• DEPARTMENT OF COMMERCE
• National Oceanic and Atmospheric Administration

[Federal Register Volume 70, Number 160 (Friday, August 19, 2005)]
[Notices]
[Pages 48675-48691]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 05-16390]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

[I.D. 022304A]


Taking and Importing Marine Mammals; Taking Marine Mammals 
Incidental to Conducting the Precision Strike Weapon (PSW) Testing and 
Training by Eglin Air Force Base in the Gulf of Mexico

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

ACTION: Notice of issuance of an incidental harassment authorization.

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SUMMARY: In accordance with provisions of the Marine Mammal Protection 
Act (MMPA) as amended, notification is hereby given that an Incidental 
Harassment Authorization (IHA) to take marine mammals, by harassment, 
incidental to testing and training during Precision Strike Weapon (PSW) 
tests in the Gulf of Mexico (GOM), a military readiness activity, has 
been issued to Eglin Air Force Base (Eglin AFB).

DATES: Effective from July 28, 2005, through July 27, 2006.

ADDRESSES: The application, a list of references used in this document, 
and/or the IHA are available by writing to Steve Leathery, Chief, 
Permits, Conservation and Education Division, Office of Protected 
Resources, National Marine Fisheries Service, 1315 East-West Highway, 
Silver Spring, MD 20910-3225, or by telephoning the contact listed 
here. A copy of the Final Environmental Assessment (Final EA) is 
available by writing to the Department of the Air Force, AAC/EMSN, 
Natural Resources Branch, 501 DeLeon St., Suite 101, Eglin AFB, FL 
32542-5133. Documents cited in this notice may be viewed, by 
appointment, during regular business hours, at the aforementioned 
address.

FOR FURTHER INFORMATION CONTACT: Kenneth R. Hollingshead, NMFS, 301-
713-2055, ext 128.

SUPPLEMENTARY INFORMATION:

Background

    Sections 101(a)(5)(A) and 101(a)(5)(D) of the Marine Mammal 
Protection Act (16 U.S.C. 1361 et seq.)(MMPA) direct the Secretary of 
Commerce (Secretary) to allow, upon request, the incidental, but not 
intentional taking of small numbers of marine mammals by U.S. citizens 
who engage in a specified activity (other than commercial fishing) 
within a specified geographical region if certain findings are made and 
regulations are issued or, if the taking is limited to harassment, a 
notice of a proposed authorization is provided to the public for 
review. In 2004, The National Defense Authorization Act (NDAA) (Public 
Law 108-136) amended section 101(a)(5) of the MMPA to exempt military 
readiness activities from the ``specified geographical region'' and 
``small numbers'' requirements.
    An authorization may 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 monitoring and reporting of such 
takings are set forth. NMFS has defined ``negligible impact'' in 50 CFR 
216.103 as ''...an impact resulting from the specified activity that 
cannot be reasonably expected to, and is not reasonably likely to, 
adversely affect the species or stock through effects on annual rates 
of recruitment or survival.z4''
    Section 101(a)(5)(D) of the MMPA established an expedited process 
by which citizens of the United States can apply for an authorization 
to incidentally take small numbers of marine mammals by harassment. The 
NDAA amended the definition of ``harassment'' in section 18(A) of the 
MMPA as it applies to a ``military readiness activity'' to read as 
follows:
    (i) any act that injures or has the significant potential to 
injure a marine mammal or marine mammal stock in the wild [Level A 
harassment]; or (ii) any act that disturbs or is likely to disturb a 
marine mammal or marine mammal stock in the wild by causing 
disruption of natural behavioral patterns, including, but not 
limited to, migration, surfacing, nursing, breeding, feeding, or 
sheltering, to a point where such behavioral patterns are abandoned 
or significantly altered [Level B harassment].

Summary of Request

    On February 4, 2004, Eglin AFB submitted a request for a 1-year IHA 
under section 101(a)(5)(D) of the MMPA and for an authorization under 
section 101(a)(5)(A) of the MMPA (to take effect after the expiration 
of the IHA), for the incidental, but not intentional taking (in the 
form of noise-related harassment), of marine mammals incidental to PSW 
testing within the Eglin Gulf Test and Training Range (EGTTR) for the 
next 5 years. The EGTTR is described as the airspace over the GOM that 
is controlled by Eglin AFB; it is also referred to as the ``Eglin Water 
Range.''
    PSW missions involve air-to-surface impacts of two weapons, the 
Joint Air-to-Surface Stand-off Missile (JASSM) AGM-158 A and B and the 
small-diameter bomb (SDB) (GBU-39/B) that result in underwater 
detonations of up to approximately 300 lbs (136 kg) and 96 lbs (43.5 
kg, double SDB) of net explosive weight (NEW), respectively.
    The JASSM is a precision cruise missile designed for launch from 
outside area defenses to kill hard, medium-hard, soft, and area-type 
targets. The JASSM has a range of more than 200 nautical miles (nm) 
(370 kilometers (km)) and carries a 1,000-lb (453.6 kg) warhead. The 
JASSM has approximately 300 lbs (136 kg) of TNT equivalent NEW. The 
explosive used is AFX-757, a type of plastic bonded explosive (PBX) 
formulation with higher blast characteristics and less sensitivity to 
many physical effects that could trigger unwanted explosions. The JASSM 
would be launched from an aircraft at altitudes greater than 25,000 ft 
(7620 m). The JASSM would cruise at altitudes greater than 12,000 ft 
(3658 m)

[[Page 48676]]

for the majority of the flight profile until it makes the terminal 
maneuver toward the target. The JASSM exercise involves a maximum of 
two live shots (single) and 4 inert shots (single) each year for the 
next 5 years. One live shot will detonate in water and one will 
detonate in air. Detonation of the JASSM would occur under one of three 
scenarios: (1) Detonation upon impact with the target (about 5 ft (1.5 
m) above the GOM surface); (2) detonation upon impact with a barge 
target at the surface of the GOM; or (3) detonation at 120 milliseconds 
after contact with the surface of the GOM.
    The SDB is a glide bomb. Because of its capabilities, the SDB 
system is an important element of the Air Force's Global Strike Task 
Force. The SDB has a range of up to 50 nm (92.6 km) and carries a 
217.4-lb (98.6 kg) warhead. The SDB has approximately 48 lbs (21.7 kg) 
of TNT equivalent NEW. The explosive used is AFX-757. Launch from an 
aircraft would occur at altitudes greater than 15,000 ft (4572 m). The 
SDB would commence a non-powered glide to the intended target. The SDB 
exercise involves a maximum of six live shots a year, with two of the 
shots occurring simultaneously, and a maximum of 12 inert shots, with 
up to two occurring simultaneously. Detonation of the SDBs would occur 
under one of two scenarios: (1) Detonation of one or two bombs upon 
impact with the target (about 5 ft (1.5 m)above the GOM surface), or 
(2) a height of burst (HOB) test: Detonation of one or two bombs 10 to 
25 ft (3 to 7.6 m) above the GOM surface. No underwater detonations of 
the SDB are planned.
    The JASSM and SDBs would be launched from B-1, B-2, B-52, F-15, F-
16, F-18, or F-117 aircraft. Chase aircraft would include F-15, F-16, 
and T-38 aircraft. These aircraft would follow the test items during 
captive carry and free flight but would not follow either item below a 
predetermined altitude as directed by Flight Safety. Other assets on 
site may include an E-9 turboprop aircraft or MH-60/53 helicopters 
circling around the target location. Tanker aircraft including KC-10s 
and KC-135s would also be used. A second unmanned barge may also be on 
location to hold instrumentation. Targets include a platform of five 
containers strapped, braced, and welded together to form a single 
structure and a hopper barge, typical for transportation of grain.
    The proposed Eglin AFB action would occur in the northern GOM in 
the EGTTR. Targets would be located in water less than 200-ft (61-m) 
deep and from 15 to 24 nm (27.8 to 44.5 km) offshore, south of Santa 
Rosa Island and south of Cape San Blas.

Comments and Responses

    A notice of receipt of Eglin AFB's application and proposed IHA was 
published in the Federal Register on April 22, 2004 (69 FR 21816). That 
notice described, in detail, Eglin AFB's proposed activity, the marine 
mammal species that may be affected by the activity, and the 
anticipated effects on marine mammals. During the 30-day public comment 
period, substantial comments were received from the Marine Mammal 
Commission (Commission), the Gulf Restoration Network (GRN), and the 
Acoustic Ecology Institute (AEI). Other comments received from 
individuals on this proposed action only expressed either support for, 
or concern over, missile launches based on a news article.

MMPA Concerns

    Comment 1: The GRN has concerns that NMFS proposes to issue a 1-
year IHA, followed by a 5-year authorization to Eglin AFB. The GRN is 
unclear why NMFS is presently contemplating the issuance of an IHA when 
it has already stated its intention to propose regulations. The GRN 
asks whether the interim action is being considered to enable Eglin AFB 
and/or NMFS to complete an in-depth environmental analysis of the 
potential long-term impacts of the activity prior to making a final 
decision on the regulations. Alternatively, GRN asks, is this an 
attempt to essentially allow Eglin AFB a 6-year LOA, which GRN believes 
would be impermissible under the MMPA?
    Response: NMFS proposes to issue a 1-year IHA to Eglin AFB for its 
activities over the next 12 months. Subsequent authorizations will 
likely proceed under section 101(a)(5)(A) of the MMPA, which allows for 
take authorizations over a 5-year time horizon. The alternative to 
issuance of Letters of Authorization (LOAs) under section 101(a)(5)(A) 
regulations would be to continue processing applications under section 
101(a)(5)(D) of the MMPA, and, presumably, issue IHAs annually to Eglin 
for PSW activities. Either way, the public would be provided another 
opportunity to comment on Eglin AFB's application and NMFS' proposed 
action. We disagree that it is not permissible to follow a one-year IHA 
with a 5-year rule and regulations that govern take authorizations. The 
MMPA does not limit the number of times or the period of time over 
which an applicant can receive an incidental take authorization so long 
as all the requirements are met. For our determination under the 
National Environmental Policy Act (NEPA), see that section later in 
this document.
    Comment 2: The Commission notes that the proposed weapons test 
appear to fit within the definition of a ``military readiness 
activity'' as defined in section 315(f) of Public Law 107-314, which 
includes ``the adequate and realistic testing of military equipment, 
vehicles, weapons, and sensors for proper operation and suitability for 
combat use.'' As such, the revised definition of harassment adopted in 
the NDAA (Public Law 108-136) would seem to be applicable in this 
instance. However, NMFS' analysis of the small take request does not 
seem to have employed this definition. If NMFS' preliminary conclusion 
that no take by serious injury and/or death is anticipated, and the 
potential for temporary or permanent hearing impairment is low and will 
be avoided through the incorporation of (proposed) mitigation measures 
is correct, it may be that no taking by harassment can be expected and 
that no authorization is needed. The Commission therefore recommends 
that NMFS analyze the request for an IHA and the small take regulations 
being contemplated in light of the applicable definition of the term 
``harassment.'' Although the Commission appreciates NMFS has yet to 
promulgate regulations or take other steps to implement the new 
definition, the statutory change cannot be ignored.
    Response: In the preamble to the notice of proposed authorization 
and in this document, NMFS cited the NDAA definition of Level B 
harassment for military readiness activities. While NMFS believes that 
the monitoring to be implemented by Eglin AFB will ensure that the 
probability of Level A harassment will be very low (1-2 animals/year-
see Table 4) and mortality likely to be zero (see Table 3), an 
authorization under section 101(a)(5) of the MMPA is warranted because 
some animals may be harassed if the mitigation and monitoring overlooks 
an animal.
    Given the scientific uncertainty associated with predicting animal 
presence and behavior in the field, NMFS accords some deference to 
applicants requesting an MMPA authorization for an activity that might 
fall slightly below the NDAA definition of harassment, so that they are 
covered for impacts that may rise to the level of take. Equally 
important, such an authorization also carries with it responsibilities 
to implement mitigation

[[Page 48677]]

and monitoring measures to protect marine mammals.

Marine Mammal Impact Concerns

    Comment 3: The GRN is concerned with Eglin AFB's and/or NMFS' claim 
that the activity will only result in Level B harassment. The record 
before the agency clearly establishes the potential for injury (Level A 
harassment) or even death among marine mammals as a result of this 
testing.
    Response: Neither Eglin AFB nor NMFS have claimed that there is no 
potential for incidental injury to occur as a result of this activity. 
While the application calculated that 6-7 marine mammals may incur a 
Level A (injury) harassment, recalculation of the potential for injury 
has resulted in a revised estimate of 1-2 animals annually. Also the 
criterion for mortality is lung hemorrhage calculated for a small 
dolphin calf at 31 psi-msec. For the PSW, the zone of potential 
lethality is approximately 75-320 m (246-1050 ft) around the detonation 
point (Table 2). Table 3 provides a risk analysis that indicates that 
less than 1 cetacean might be killed annually even if no mitigation 
measures were implemented. However, NMFS believes that due to the 
mitigation measures that Eglin AFB will implement, it is very unlikely 
that any cetaceans will be killed, and injury is also unlikely as a 
result of PSW activities.
    Comment 4: The GRN notes that the Federal Register notice states 
that from 3 to as many as 103 cetaceans would potentially be exposed 
annually to 182 dB by the action and GRN contends that the impact of 
the action would therefore be more than negligible and would not be an 
appropriate subject of an IHA. The GRN disagrees with NMFS' claim that 
exposure to sound levels greater than 182 dB on possibly 13 percent of 
the GOM cetaceans would constitute only non-injurious Level B 
harassment.
    Response: Neither Eglin AFB nor NMFS claim that 13 percent of the 
GOM cetacean population might be affected by Eglin's PSW activities. As 
shown in the proposed authorization notice (69 FR 21816, April 22, 
2004), only four of the 29 species/stocks of marine mammals that 
inhabit the GOM would be within the area offshore Eglin AFB. Of the 
high estimate of 103 cetaceans that might be subject to sound exposure 
levels (SELs) of 182 dB re 1 microPa\2\-s or higher, roughly half would 
be bottlenose dolphins and half would be Atlantic spotted dolphins. No 
more than a single Kogia individual might be subject to an SEL of 182 
dB re 1 microPa2-s. As a result of an error in estimating the number of 
shots, those numbers in the application were higher than currently 
projected and analyzed in this document.
    The rationale on why exposure to an SEL of this magnitude would 
result in only Level B harassment takes (by TTS) and why these takings 
would have only negligible impacts was discussed in the proposed IHA 
authorization Federal Register notice with reference to the scientific 
basis for that reasoning. That information is also provided in detail 
later in this document. To assess impacts on marine mammals from 
explosives, NMFS and Eglin used the energy flux density (EFD) metric. 
This is also explained in the proposed IHA notice and later in this 
document.
    Comment 5: Citing from the Minerals Management Service's 2002 Draft 
Programmatic EA for GOM seismic activities, the GRN notes that a 
received sound pressure level of 180 dB re 1 micro Pa (rms) or greater 
is an indication of potential concern about temporary and/or permanent 
injury (to cetaceans, such as sperm whales). Thus, GRN believes, there 
is significant uncertainty as to whether Level A harassment would be 
limited to ``nearly 3 cetaceans'' or could instead affect 103 
cetaceans. In the face of this uncertainty, the GRN would contend that 
the no action alternative is appropriate.
    Response: The principal metric employed for determining harassment, 
injury and mortality in this action is EFD, not sound pressure levels. 
The scientific basis for employing this metric is explained in detail 
in Eglin's application and later in this document. Use of the energy 
metric has been employed in the shock trials of the USS SEAWOLF (see 63 
FR 66069, December 1, 1998) and USS WINSTON S. CHURCHILL (66 FR 22450, 
May 4, 2001).
    Comment 6: The Commission remains concerned that NMFS continues to 
categorize temporary threshold shift (TTS) as constituting Level B 
harassment, discounting the potential that diminishment of hearing 
capability in marine mammals, even if only of limited duration, may 
cause impairment that could lead to injury or even death (e.g. by 
lowering the ability of an animal to detect and avoid predators or 
ships). The Commission notes, however, that regardless of whether TTS 
is considered Level A or Level B harassment, taking could be authorized 
under a section 101(a)(5)(D) IHA, provided that mortalities do not 
occur.
    Response: As mentioned in previous Federal Register documents, 
second level impacts due to a marine mammal having a temporary hearing 
impairment cannot be predicted and are, therefore, speculative. The 
principal reason that second level impacts are not considered in 
classification is that any Level B disruption of behavior could, with 
suppositions, be seen as potentially dangerous and, therefore, 
considered potential Level A harassment or even lethal. Similarly, 
Level A injuries could be seen as being accompanied by some disruption 
of behavior and, therefore, with both Level B disturbances and Level A 
injuries. Such reasoning blurs the distinctions between the definitions 
of harassment. NMFS believes that Level B harassment, if of sufficient 
degree and duration, can be very serious and require consideration, as 
has been done here. Moderate TTS does not necessarily mean that the 
animal cannot hear, only that its threshold of hearing is raised above 
its normal level. The extent of time that this impairment remains is 
dependent upon the amount of initial TS, which depends on the strength 
of the received sound and whether the TTS is in a frequency range that 
the animal depends on for receiving cues that would benefit survival. 
It should be noted that increased ambient noise levels, due to 
biologics, storms, shipping, and tectonic events may also result in 
short-term decreases in an animal's ability to hear normally. NMFS 
scientists believe that marine mammals have likely adopted behavioral 
responses, such as decreased spatial separation, slower swimming 
speeds, and cessation of socialization to compensate for increased 
ambient noise or hearing threshold levels.
    Ship strikes of whales by large vessels suggest that at least 
certain species of large whales do not use vessel sounds to avoid 
interactions. Also, there is no indication that smaller whales and 
dolphins with TTS would modify behavior significantly enough to be 
struck by an approaching vessel. Finally, a hypothesis that marine 
mammals would be subject to increased predation presumes that the 
predators would either not be similarly affected by the detonation or 
would travel from areas outside the impact zone, indicating recognition 
between the signal of a single detonation at distance and potentially 
debilitated food sources. Therefore, NMFS does not believe the evidence 
warrants that all (or an unknown percentage) of the estimated numbers 
of Level B harassment be considered as Level A harassment or as 
potential mortalities.
    Comment 7: The Commission states that NMFS seems to discount 
entirely the possibility that marine mammals may be harassed through 
changes in behavioral patterns other than by TTS.

[[Page 48678]]

 The basis for this conclusion is not clear from the discussion on page 
21819 of the Federal Register notice. Additional explanation is needed 
and should consider, among other things, whether marine mammals might 
alter their use patterns in the vicinity of detonations, or even 
abandon an area, as a result of infrequent or even a one-time exposure.
    Response: NMFS does not have information to support the 
Commission's hypothesis that marine mammals would abandon or 
significantly alter their natural behavioral patterns in response to a 
single explosive detonation. Contrary to this hypothesis, NMFS believes 
that, unless the mammal was transiting the area, it is unlikely that a 
marine mammal would leave an area that provides important biological 
resources for sustenance and reproductive success from the sounds from 
a single distant water detonation (presuming here that it is more 
likely that an animal will spend the majority of its time in a 
biologically important area). In fact, the GOM has thousands of 
lightning strikes annually (approximately 10 strikes per sq km per year 
in the GOM with source levels of about 260 dB re 1 microPa (peak)(NASA, 
2005). It is likely that marine mammals are evolutionarily adapted to 
natural events such as tectonics and lightning storms, which have 
similar characteristics to the explosives in this action. In the 
absence of additional information, NMFS concludes that a marine mammal 
may be startled by the received sound level from a single explosive 
detonation if near enough to the source, but it is highly unlikely that 
marine mammals would abandon or significantly alter their behavior 
patterns. Therefore, we do not believe effects rise to the level of a 
significant alteration or abandonment of natural behavioral patterns, 
i.e., Level B harassment. In any case, Level B takes are counted 
insofar as we consider TTS to be Level B harassment.
    Comment 8: The Commission believes that NMFS needs to provide a 
better explanation of, and justification for, using the dual criteria 
established for determining non-lethal injury (i.e., the onset of 
slight lung hemorrhage and a 50 percent probability for eardrum 
rupture).
    Response: Explanation and justification were provided in detail in 
both the SEAWOLF and CHURCHILL Final EISs (DoN 1998 and DoN 2001). An 
updated summary for using the dual injury criteria from those documents 
is provided here:

1. Auditory System Injury
    Tympanic membrane (TM) rupture, while not necessarily a serious or 
life-threatening injury, is a useful index of injury that is well 
correlated with measures of permanent hearing loss (Ketten, 1995, 
1998). The occurrence of 50 percent TM rupture has been correlated to 
30 percent permanent threshold shift (PTS) (Ketten, 1995, 1998) and 
will be considered as the index for permanent auditory system injury. 
In this response, the criteria will be explained for conservatively 
estimating the range for occurrence of 50-percent TM rupture (30-
percent PTS). Significant occurrence of TM rupture would be expected at 
``near field'' ranges significantly closer to the charge than the 
ranges for TTS and onset of PTS. For the CHURCHILL EIS injury model, TM 
rupture criteria were based on a limited number of small charge 
underwater explosion tests conducted with small terrestrial mammals as 
reported by both Yelverton et al. (1973) and Richmond et al. (1973). TM 
rupture-specific tests were conducted with post-mortem dogs (nominal 
25-kg body mass) using 1-lb (0.45-kg) TNT charges. Additional TM 
rupture data from general injury tests conducted with sheep (nominal 
40-kg body mass) using 0.5-lb and 1-lb (0.23-kg and 0.45-kg) pentolite 
charges were also included.
    Damage to terrestrial mammal internal organs typically has been 
referenced to total shock wave impulse (pressure integrated over time) 
(Richmond et al. (1973) and Yelverton et al. (1973)). Yelverton et al. 
(1973) state that eardrum ruptures would occur at sub-lethal impulses 
of 20 to 40-psi-msec (138 to 276-Pa-sec) and that an impulse of 10-psi-
msec (69-Pa-sec) or less would not cause eardrum ruptures.
    Acoustic energy (proportional to the square of pressure integrated 
over time) may be one of the appropriate parameters for evaluation of 
the response of the mammalian ear to the intensities of underwater 
noise at least sufficient to cause TTS. The shock wave's EFD appears to 
be at least as good an indicator/predictor of auditory system injury 
(TM rupture) as impulse and, for the CHURCHILL shock trial conditions, 
provided a means to include the potential effects of the bottom-
reflected pressure wave.
    Logarithmic interpolation of the test data for EFDs for 42 percent 
and 67 percent TM rupture indicates that the calculated EFD required 
for the occurrence of 50 percent TM rupture (approximately 30 percent 
PTS) is 1.17 in-lb/in2 (20.44 milli-Joules/cm\2\). The small sample 
sizes for the reported terrestrial animal test data in combination with 
the inherent variability in the occurrence of TM rupture at levels less 
than approximately 50 percent preclude realistic predictions of low 
percentages of occurrence of TM rupture.
2. Onset of Slight Lung Injury
    Using data from tests with small terrestrial mammals from Yelverton 
et al. (1973) and Richmond et al. (1973), Goertner (1982) developed a 
conservative model for calculating the ranges for occurrence of two 
types of internal organ injury to marine mammals exposed to underwater 
explosion shock waves. The two injury mechanisms considered are (1) 
slight lung hemorrhage, and (2) contusions and hemorrhage of the 
gastrointestinal (G.I.) tract. For lung hemorrhage, the Goertner model 
considers lung volume as a function of animal weight and depth and 
considers shock wave duration and impulse tolerance as a function of 
animal weight and depth. Goertner indicated that slight injury to the 
G.I. tract could be related to the magnitude of the peak shock wave 
pressure over the hydrostatic pressure and would be independent of 
mammal size and weight. Slight contusions to the G.I. tract occurred 
during small charge tests (Richmond et al., 1973) when the peak shock 
wave pressure was 104 psi above hydrostatic pressure. Onset of G.I. 
tract contusion and onset of slight lung hemorrhage are injuries from 
which a mammal would be expected to recover on its own and would not be 
debilitating. For small mammals, significant G.I. tract injury (G.I. 
tract hemorrhage) would be expected to occur at ranges significantly 
closer to the explosion than the maximum calculated ranges for the 
onset of slight lung injury. Injury ranges determined on the basis of 
the Goertner model are most appropriate for use in regions close to the 
explosive charge.
    After correcting for the atmospheric and hydrostatic pressures for 
the data, the minimum impulse (I) for predicting onset of slight lung 
hemorrhage in a small mammal is:
I = 19.7 (M/42)1/3 psi-msec, or
I = 136 (M/42)1/3 Pa-sec,
    where M is the body mass (in kg) of the subject animal. Impulse 
values from the above equation provide a shallow depth ``starting 
point'' for determining the maximum range and the corresponding ``at-
depth'' impulse level for the specific charge weight and marine mammal 
size. A maximum range should not be calculated using only the above 
impulse/body mass relationship

[[Page 48679]]

and the total impulse similitude equation for a specific explosive.
    The modified Goertner model is very sensitive to mammal weight. By 
assuming a small mammal weight for an impact analysis, the onset of 
slight injury range is maximized for conservatism. Injuries from 
explosions in relatively shallow water (i.e., on the continental shelf) 
may be exacerbated by strong bottom-reflected pressure pulses.
    Comment 9: In reviewing NMFS' May 4, 2001, response to the 
Commission's January 26, 2001, comments (see 66 FR 22456, May 4, 2001), 
NMFS appears to agree with the Commission that eardrum rupture is a 
questionable measure of acoustic injury in marine mammals. NMFS notes 
that ``(b)ecause the criterion is based upon land mammals rather than 
marine mammals, and because TM (tympanic membrane) rupture research has 
not been conducted on marine mammals, it is not the 50-percent rupture 
itself that is the criterion used, but the 'impulse' in psi-msec that 
is associated with other impacts on the body...the EFD that causes 
either the 50 percent TM rupture or the impulse that causes slight lung 
hemorrhage is the real criterion.'' NMFS' response further indicates 
that ``because the impulse estimated to cause slight lung hemorrhage 
was more conservative (i.e., had a greater range), it is slight lung 
hemorrhage that is the defining criterion used for determining injury 
in this action, not the EFD used for 50-percent TM rupture.'' Based on 
this explanation, it appears that the 50 percent probability for 
eardrum rupture is not a useful metric in that it cannot be measured. 
In essence, the probability for eardrum rupture substitutes for another 
metric (PTS), which also cannot be measured. Because of these 
difficulties, neither metric is ultimately used in setting the safety 
zone.
    Response: Although non-lethal impact cannot be measured for wild 
animals at the time of the action, acoustic thresholds for injury have 
been derived from tests on terrestrial animals in water. These 
thresholds are the best science available today. For the subject 
action, the impact range determined from the lung injury threshold is 
the most conservative. However, in other actions, the eardrum rupture 
threshold may be more conservative. For that reason, the dual criteria 
are needed to use a conservative approach for determining injury ranges 
for the variety of explosive activities considered by NMFS for 
incidental take authorizations.
    Comment 10: Related to the previous comment, the Commission notes 
that both the May 4, 2001, and the April 22, 2004, Federal Register 
notices give a value of EFD that would cause 50 percent probability of 
TM rupture, but provide no reference for this value and no indication 
of the signal waveform or the time interval over which the energy 
density flux is integrated. Before using this value of EFD as the 
threshold of Level A harassment for an authorization, the applicant or 
NMFS needs to provide the waveform and integration time interval and 
explain the scientific basis for this choice.
    Response: Explanation and reference for the EFD value are found in 
response to comment 8. The nominal source waveform at unit distance 
used for the Air Force risk assessment modeling is defined as follows:
p(t) = 0 for t <0
p(t) = pmax exp (-t/t) for t > 0
    where p(t) is pressure as a function of time, t. Pmax represents 
peak pressure at unit distance and t is the characteristic time at unit 
distance. The waveform and parameters are estimated using the 
similitude formulas of Weston (1960) (see, e. g., Urick, 1983)(note 
that this is the Friedlander waveform).
    Consistent with NMFS' SEAWOLF and CHURCHILL rulemakings and the 
Navy's NEPA analyses for those actions, no bubble pulses were included 
(and are not considered important for near surface shots). The 
waveforms were 'propagated' using the similitude-based peak pressures 
and characteristic times as functions of distance. The propagation 
model was the Navy standard CASS-GRAB model, modified to calculate 
impulse response of the channel.
    At range, the squared pressure for the entire set of arrivals was 
integrated over time, and normalized by the scalar acoustic impedance, 
to yield total energy (i.e., the integration was over the duration of 
all arrivals).
    Comment 11: The Commission believes that additional clarification 
and justification is needed concerning the ``non-injurious behavioral 
response'' threshold proposed in Table 6-1 on page 14 of the 
application. The applicant suggests a level of 6 dB below TTS (i.e., 
176 dB re 1 microPa\2\-sec) as a reasonable criterion to assess 
potential behavioral responses of marine mammals. However, neither the 
application nor the NMFS notice provides information as to how this 
number was derived. Prior to issuing the requested authorization, the 
applicant or NMFS should provide additional information to support the 
scientific basis for using this criterion.
    Response: As noted in the proposed authorization notice, the PSW 
action consists of single detonations. Based on the science used to 
develop the CHURCHILL criteria, for single detonations a significant 
response by a marine mammal is not expected to occur other than by TTS. 
The discussion in the application and Federal Register notice is 
relevant to actions involving multiple detonations. NMFS will address 
comments on this threshold criterion in an applicable proposed IHA 
authorization with multiple detonations.
    Comment 12: The Commission notes that the Federal Register notice 
for the proposed IHA states that, in its rulemaking on the CHURCHILL 
ship shock testing, NMFS adopted two criteria for estimating the TTS 
threshold: 182 dB and 12 psi. The notice states that the second 
criterion ``was introduced to provide a more conservative safety zone 
for TTS when the explosive or the animal approaches the sea surface 
(for which the explosive energy is reduced but the peak pressure is 
not).'' The notice states that ``for large explosives (2,000 to 10,000 
lbs) and explosives/animals not too close to the surface, the TTS 
impact zones for these two TTS criteria are approximately the same. 
However, for small detonations, some acousticians contend that ranges 
for the two TTS thresholds may be quite different, with ranges for the 
peak pressure threshold several times greater than those for energy.'' 
NMFS notes that the applicant is endorsing an approach being developed 
by the Navy for ``scaling'' the peak pressure threshold in order to 
estimate more accurately the TTS for small detonations while preserving 
the safety feature provided by the peak pressure threshold. The 
Commission recommends that, in any authorization issued to Eglin AFB, 
NMFS provide the full set of data, assumptions, and calculations 
considered in its review.
    Response: This issue remains under review by the Navy, the U.S. Air 
Force and NMFS. Navy acousticians believe that Ketten (1995), which 
summarized earlier acoustic research, does not fully support using a 
12-psi peak pressure threshold for TTS for underwater explosion impacts 
on marine mammals from small detonations. The original basis in Ketten 
(1995) for the use of the 12-psi threshold for the SEAWOLF and 
CHURCHILL actions (which were 10,000 lb (4,536 kg) detonations) is the 
use of a combination of in-air and in-water peak pressure measurements 
without adjustment for the medium. A re-examination of the basis for 
the 12-psi threshold by Navy acousticians indicate that, for underwater 
explosions of small charges, a higher threshold may

[[Page 48680]]

be warranted. This led the Navy and Eglin to suggest scaling 12 psi for 
small charges, which was used in the proposed authorization notice and 
analysis. Although this issue remains under review by NMFS and the Navy 
for future rulemaking actions (including the upcoming PSW proposed 
rule), as an interim criterion for this IHA, NMFS is adopting the 
experimental findings of Finneran et al. (2002) that TTS can be induced 
at a pressure level of 23 psi (at least in belugas). As explained here, 
this is considered conservative since a 23 psi pressure level was below 
the level that induced TTS in bottlenose dolphins.
    Finneran et al. (2000; as described in Finneran et al. (2002)) 
conducted a study designed to measure masked TTS (MTTS) in bottlenose 
dolphins and belugas exposed to single underwater impulses. This study 
used an ``explosion simulator'' (ES) to generate impulsive sounds with 
pressure waveforms resembling those produced by distant underwater 
explosions. No substantial (i.e., 6 dB or larger) threshold shifts were 
observed in any of the subjects (two bottlenose dolphins and 1 beluga) 
at the highest received level produced by the ES: approximately 70 kPa 
(10 psi) peak pressure, 221 dB re re 1 micro Pa peak-to-peak (pk-pk) 
pressure, and 179 dB re 1 microPa\2\-s total EFD. In Finneran et al. 
(2002), a watergun was substituted for the ES because it is capable of 
producing impulses with higher peak pressures and total energy fluxes 
than the pressure waveforms produced using the ES. It was also 
preferable to other seismic sources because its impulses contain more 
energy at higher frequencies, where odontocete hearing thresholds are 
relatively low (i.e., more sensitive). Hearing thresholds were measured 
at 0.4, 4 and 30 kHz. MTTSs of 7 and 6 dB were observed in the beluga 
at 0.4 and 30 kHz, respectively, approximately 2 minutes following 
exposure to single impulses with peak pressures of 160 kPa (23 psi), 
pk-pk pressures of 226 dB re 1 microPa, and total EFD of 186 dB re 1 
microPa\2\-s. Thresholds returned to within 2 dB of the pre-exposure 
value approximately 4 minutes post exposure. No MTTS was observed in 
the single bottlenose dolphin tested at the highest exposure 
conditions: peak pressure of 207 kPa (30 psi), 228 dB re 1 microPa pk-
pk pressure, and 188 dB re 1 microPa\2\-s total energy flux. Therefore, 
until additional scientific information is obtained, NMFS has 
determined that the pressure criterion for small explosions can be 
raised from 12 psi to 23 psi. At this time, NMFS believes that setting 
the pressure metric at 23 psi is conservative.
    It should be noted that the PSW mission includes only a single 
JASSM detonation in water, all other detonations are in-air 
detonations. Analyses indicate that the ranges for the 23- psi TTS 
metric at depths greater than 20 ft (6.1 m) are less conservative than 
the originally provided ranges for the 182-dB (re 1 microPa\2\-s) TTS 
energy metric. Conversely, ranges for the 23-psi TTS metric in air and 
at the 1-ft (0.3-m) water depth are more conservative than the ranges 
originally provided for the 182-dB energy metric. For the PSW activity, 
NMFS will use the more conservative values to determine impacts (Table 
1).
BILLING CODE 3510-22-S
[GRAPHIC] [TIFF OMITTED] TN19AU05.008

BILLING CODE 3510-22-C

[[Page 48681]]

Mitigation and Monitoring Concerns

    Comment 13: Based on the information contained in the application 
and Federal Register notice, the Commission believes that NMFS' 
preliminary determinations are reasonable, provided that the proposed 
mitigation and monitoring activities are adequate to detect all marine 
mammals in the vicinity of the proposed operations and sufficient to 
ensure that marine mammals are not being taken in unanticipated ways or 
numbers. The Commission notes however, that even under the best of 
conditions and using experienced observers, there is greater than an 80 
percent likelihood that small cetaceans, particularly species such as 
dwarf or pygmy sperm whales, will not be observed if they are in the 
vicinity of the test site. Thus, although there may be a low 
probability that certain marine mammal species will be within the area 
where mortalities are considered possible at the time of weapon 
deployment, it is unclear that the proposed monitoring effort will be 
adequate to detect them if they are present. This being the case, the 
proposed monitoring activities may be insufficient to provide assurance 
that marine mammals are not being exposed to sound pressures or energy 
levels that could cause lethal injuries. Thus, NMFS, before issuing the 
requested authorization, should further explain its rationale for 
determining that the takings will only be by harassment.
    Response: The monitoring effort for PSW is similar to that used in 
previous ship-shock actions wherein detonations of 10,000 lbs (4536 kg) 
were used without any serious injuries or mortalities being detected 
during extensive follow-up monitoring. While dwarf/pygmy sperm whales 
are unlikely to be in the general area and, therefore, not subject to 
potential injury or mortality, past shock trial exercises considered 
the detection of these species to be 50 percent by vessel observers and 
10 percent by aerial observers. For the bottlenose and spotted 
dolphins, detection by shipboard observers is 100 percent and aerial 
observers at 50 percent giving an overall detection capability of 90 
percent (DON, 1999, Appendix C). However, for safety reasons, 
monitoring personnel will need to vacate the respective safety zones in 
advance of detonation, as explained later in this document (see Table 6 
in Mitigation). As a result, Eglin AFB and NMFS calculate an overall 
monitoring effectiveness of 30 percent for all species. Table 3 in this 
document indicates that the risk for a lethal take of an individual 
marine mammal from all PSW exercises with a 30-percent mitigation 
effectiveness is less than one animal.
    There is a scientific methodology to estimate the probability of 
detecting marine mammals during vessel assessment surveys, as explained 
in detail in Buckland et al. (1993) and Barlow (1995). Methodology 
includes several components, including the probability that the mammal 
will be at the surface and potentially sightable while within visual 
range of the observers, the probability that an animal at the surface 
will in fact be detected, and the relationship between sighting 
probability and lateral distance from the ship's trackline. One factor 
providing better detection rates for Kogia spp. for this action is that 
the vessel observers will be monitoring a relatively small area, not 
conducting track line surveys at a high rate of speed as done in NMFS 
marine mammal abundance surveys. In addition, Eglin will be conducting 
aerial marine mammal surveys over an area of 12.56 nm\2\ (2-nm (3.7-km) 
radius), further precluding animals from entering the safety zone 
undetected. As a result of all of these factors, NMFS is confident that 
no marine mammals will be killed as a result of Eglin's PSW activities.
    Comment 14: The Commission recommends that, if NMFS determines that 
the potential for lethal injuries is sufficiently remote to warrant the 
issuance of an authorization under section 101(a)(5)(D) of the MMPA, 
any such authorization explicitly require that operations be suspended 
immediately if a dead or seriously injured animal is found in the 
vicinity of the test site, pending authorization to proceed or issuance 
of regulations authorizing such takes under section 101(a)(5)(A) of the 
MMPA.
    Response: Testing consists of a single exercise with a single 
detonation with weeks or months likely between detonations. As a 
result, if a seriously injured or dead marine mammal is found in the 
vicinity of the test operations do not need to be ``immediately 
suspended,'' but future tests will not occur until the serious injury 
or mortality has been investigated as to likely cause.
    Comment 15: The GRN and the AEI find that the proposed mitigation 
is inadequate to protect marine species in the GOM. Both groups claim 
that visual monitoring is not an effective method for detecting all 
cetaceans. The GRN notes that sperm whales, for instance, are known for 
their extremely long, deep-water dives. Up to 5000 ft (1524 m) dives 
have been reported for periods up to 2 hours long. The animals would 
not be visible to observers in either a helicopter 250 ft (76.2 m) 
above the surface of the water or on board a ship, and they could 
easily surface unnoticed in an area impacted by the testing. Reliance 
on visual monitoring is not sufficient to adequately protect cetacean 
populations in the GOM. Instead, if allowed to proceed with the 
proposed activity, Eglin AFB should be required to use passive acoustic 
monitoring to ensure that impacts to protect species are minimal.
    Response: While sperm whales and other deep-diving marine mammals 
may remain submerged for long periods of time, the proposed action 
would be located in waters less than 200 ft (61 m) deep. This habitat 
is not expected to be utilized by sperm whales or beaked whales. The 
marine mammal species that inhabit the waters off Eglin AFB are the 
bottlenose dolphin, spotted dolphin and possibly Kogia. Other than 
Kogia, these species are easily sighted from aircraft and ships. While 
Kogia are more difficult to see, restricting exercises to sea states 
lower than 4, having aerial coverage in addition to shipboard 
observers, and the small zone for Level A harassment, should eliminate 
the likelihood that Kogia or other marine mammal species would be 
injured or killed. Therefore, requiring the use of passive acoustics is 
not warranted.
    Comment 16: The GRN is also concerned by Eglin AFB's apparent 
emphasis on post-mission monitoring (affording 2 hours of aerial 
surveys after the activity and only one hour of continuous aerial 
surveying prior to detonation of the weapons). The GRN believes that, 
although post-mission monitoring is important, major emphasis should be 
placed on preventing harm, not quantifying the number of dead and 
injured marine mammals and sea turtles.
    Response: NMFS believes that both pre-detonation monitoring and 
post-detonation monitoring are important. Eglin will begin vessel 
surveys 5 hours prior to the test and aerial surveys of the test site 2 
hours prior to the proposed time of detonation (Eglin, 2004). For 
safety reasons, aircraft and ships will need to begin exiting the area 
15 minutes prior to detonation (see Table 6). While it is very unlikely 
that marine mammals will enter the relatively small impact zone between 
the time vacating the area and the time of detonation, post monitoring 
will provide valuable information on whether current mitigation 
measures are fully effective at preventing mortality and serious 
injury.
    Comment 17: The AEI believes that NMFS should consider the use of 
active

[[Page 48682]]

acoustic systems (i.e., fish-finding sonar) to identify large schools 
of fish and/or individual sea turtles that may be affected by the 
bombing exercises.
    Response: Large fish schools and sea turtles will be more 
effectively sighted by the marine mammal monitoring aircraft than by 
standard ``fish finding'' sonars. However, to the extent that the 
monitoring vessel can utilize its acoustic equipment to detect fish 
schools and sea turtles, NMFS recommends that it do so. This acoustic 
equipment is of low intensity and, therefore, is not expected to result 
in marine mammal harassment. However, the use of more sophisticated 
high-intensity military sonars are not recommended for use as a 
mitigation/monitoring tool here because of its potential impacts to 
marine mammals and other marine life.
    Comment 18: The AEI notes that the recent calibration test for 
Lamont-Doherty Earth Observatory's marine seismic array in the GOM 
indicates that in relatively shallow water, loud low-frequency acoustic 
sources may lead to received levels of concern at greater distances 
than current models would suggest. As a result, received level models 
of the bombing exercises should be based at least on the most recent 
propagation models. Also, the most reliable safety radii would be 
determined by real-world tests in the areas planned for the exercises.
    Response: The model employed by L-DEO for seismic arrays is 
different from the model used by Eglin and the Navy for explosives. The 
subject risk assessment employs the CASS/GRAB Navy Standard propagation 
model and Navy Standard environmental databases (including bathymetry, 
sound speed, and 15-parameter geo-acoustic sediment properties). These 
are considered state of the art. The propagation model starts with 
impulse response and accounts for multipath propagation in the water 
column and in the sediments. Hence, it estimates the effects of the 
'bottom' in shallow water. For sediments like those found at the 
coastal water sites for Eglin's risk assessment, propagation of sound 
energy at the lower frequencies (below several hundred Hertz) is 
generally much better than that in deep water. This enhanced 
propagation for energy metrics is included in the range estimates for 
the risk assessment.
    It should be noted that sound propagation in shallow water has been 
a topic of intense study and measurement for at least 50 years, 
primarily by the U.S. Navy, but also by other nations and international 
bodies. Shallow-water bottom effects('reverberant' multipaths, shallow 
water waveguides, low-frequency cutoff, influence of sea state, etc.) 
are all covered in most basic underwater-acoustics textbooks (e.g., 
Urick, 1967).
    Comment 19: The GRN questions whether post-activity monitoring, 
when limited to 2 hours, can accurately estimate the effectiveness of 
pre-activity monitoring. While many dead marine mammals and sea turtles 
may rise to the surface immediately after the mission, it is possible 
that the lethal impacts of the activity may not be immediate. As a 
result, sea turtles and marine mammals may resurface days later, float 
to shore, and may or may not be reported to a stranding network.
    Response: Considering the extensive pre-mission mitigation measures 
implemented to prevent injury or mortality, NMFS believes it is 
unnecessary to remain at the site with vessels and aircraft for longer 
periods of time after completion of a test. Eglin AFB will coordinate 
its activities with the NMFS stranding network and with local stranding 
networks to locate any stranded marine mammals after an event. In 
addition, Eglin AFB maintains its own stranding network team. Stranding 
events are tracked by year, season and NMFS statistical zone, both 
Gulf-wide and along the coastline of Eglin AFB.

Activity Concerns

    Comment 20: The GRN notes that in the event that a live warhead 
fails to explode during the strike, Eglin AFB will likely detonate the 
warhead where it fell to the bottom of the ocean. An underwater 
detonation creates a much larger chance of injury or death to all 
marine species, yet Eglin does not provide an adequate description of 
the level of potential impact to protected species taken under that 
scenario.
    Response: The noise analysis was conservatively modeled by Eglin 
for 20 ft (6 m) below the surface in order to cover any water depth, 
including detonation on the sea bottom. There would be no difference in 
the noise zone of influence from what is modeled and mitigated from a 
20-ft (6 m) depth detonation and a bottom detonation. However, the 
missile itself is programmed to lose power and will not detonate after 
15 minutes. Therefore, it is safe to retrieve the missile after 15 
minutes and they do not need to be detonated on-site.

Description of Marine Mammals Affected by the Activity

    There are 29 species of marine mammals documented as occurring in 
Federal waters of the GOM. Information on those species that may be 
impacted by this activity are discussed in the Eglin AFB application 
and the Draft EA. A summary of that information is provided in this 
section.
    General information on these species can be found in Wursig et al. 
(2000. The Marine Mammals of the Gulf of Mexico, TAMU Press, College 
Station, TX) and in the NMFS Stock Assessment Reports (Waring, 2002). 
This latter document is available at: https://www.nmfs.noaa.gov/prot_
res/PR2/Stock_Assessment_Program/sars.html#Stock Assessment Reports
    Marine mammal species that potentially occur within the EGTTR 
include several species of cetaceans and one sirenian, the West Indian 
manatee. During winter months, manatee distribution in the GOM is 
generally confined to southern Florida. During summer months, a few may 
migrate north as far as Louisiana. However, manatees primarily inhabit 
coastal and inshore waters and rarely venture offshore. PSW missions 
would be conducted offshore. Therefore, effects on manatees are 
considered very unlikely.
    Cetacean abundance estimates for the study area are derived from 
GulfCet II (Davis et al., 2000) aerial surveys of the continental shelf 
within the Minerals Management Service Eastern Planning Area, an area 
of 70,470 km\2\. Texas A&M University and NMFS conducted these surveys 
from 1996 to 1998. Abundance and density data from the aerial survey 
portion of the survey best reflect the occurrence of cetaceans within 
the EGTTR, given that the survey area overlaps approximately one-third 
of the EGTTR and nearly the entire continental shelf region of the 
EGTTR where military activity is highest. The GulfCet II aerial surveys 
identified different density estimates of marine mammals for the shelf 
and slope geographic locations. Only the shelf data is used because PSW 
missions will only be conducted on the shelf.
    In order to maximize species conservation and protection, the 
species density estimate data were adjusted to reflect more realistic 
encounters of these animals in their natural environment. Refer to 
``Conservative Estimates of Marine Mammal Densities'' in this document 
and Eglin AFB's application for more information on density estimates. 
A brief description of each marine mammal species observed during 
GulfCet II aerial surveys on the shelf that has the potential to be 
present in the PSW test area is summarized here.

[[Page 48683]]

Atlantic Bottlenose Dolphins (Tursiops truncatus)

    Bottlenose dolphins are distributed worldwide in tropical and 
temperate waters. In the GOM, several coastal and offshore stocks have 
been identified (see Waring et al. 2002) and one stock occurs in the 
inshore waters of the entire GOM. Waring et al. (2002) provides the 
following minimum population estimates for the GOM bottlenose dolphin 
stocks: outer shelf, 43,233; shelf and slope, 4,530; western Gulf, 
2,938; northern Gulf, 3,518; eastern Gulf, 8,953; and Bay, Sound & 
Estuarine waters, 3,933. Baumgartner et al. (2001) suggest a bimodal 
distribution in the northern GOM, with a shelf population occurring out 
to the 150-m (492 ft) isobath and a shelf break population out to the 
750-m (2461 ft) isobath. Occurrence in water with depth greater than 
1,000 m (3281 ft) is not considered likely. Migratory patterns from 
inshore to offshore are likely associated with the movements of prey 
rather than a preference for a particular habitat characteristic (such 
as surface water temperature) (Ridgeway, 1972; Irving, 1973; Jefferson 
et al., 1992).
    The average herd or group size of Atlantic bottlenose dolphins in 
shelf and slope waters was approximately four and 10 individuals, 
respectively, per herd as determined by GulfCet II surveys of eastern 
Gulf waters (Davis et al., 2000). The diet of Atlantic bottlenose 
dolphins consists mainly of fish, crabs, squid, and shrimp (Caldwell 
and Caldwell, 1983).

Atlantic Spotted Dolphins (Stenella frontalis)

    Atlantic spotted dolphins are endemic to the tropical and warm 
temperate Atlantic Ocean. This species ranges from the latitude of Cape 
May, NJ, along mainland shores to Venezuela, including the GOM and 
Lesser Antilles (Caldwell and Caldwell, 1983). Sightings of this 
species are concentrated along the continental shelf and shelf edge 
(Fritts et al., 1983), but they also occur farther offshore. At one 
time, Atlantic spotted dolphins were considered to be the most abundant 
species of dolphin in offshore waters (Schmidly, 1981), with most 
sightings occurring at an average of 168 km (90.7 nm) offshore. The 
best available abundance estimate for this species in the northern GOM 
is the combined estimate of abundance for both the OCS (39,307, 
CV=0.31) and oceanic (238, CV=0.87) waters from 1996 to 2001, which is 
39,545 (CV=0.31)(NMFS, 2003).
    The preferred depth of the spotted dolphin is believed to be 
associated with food availability and water temperature. The diet of 
the Atlantic spotted dolphin consists of squid and fish.

Dwarf Sperm Whales and Pygmy Sperm Whales

    Dwarf sperm whales (Kogia simus) commonly inhabit the deeper 
offshore water, generally eating squid, crustaceans, and fish (Caldwell 
and Caldwell, 1983), but they do move into inshore waters during 
calving season. The pygmy sperm whale (Kogia breviceps) has a diet 
similar to that of the dwarf sperm whale. Both pygmy and dwarf sperm 
whales have been sighted in the northern GOM primarily along the 
continental shelf edge and in deeper shelf waters during all seasons 
except winter (Mullin et al., 1994). The estimate of abundance for 
dwarf and pygmy sperm whales in oceanic waters is 809 (CV=0.33)(Mullin 
and Fulling, in prep), which is the best available abundance estimate 
for these species in the northern GOM. Separate estimates of abundance 
cannot be made due to uncertainty of species identification (NMFS, 
2003). Dwarf and pygmy sperm whales have a high percentage of 
strandings relative to percent population of all cetaceans (Mullin et 
al., 1994).

Impacts to Marine Mammals

    Potential impacts to marine mammals from the detonation of the PSWs 
and SDBs include both lethal and non-lethal injury, as well as Level B 
behavioral harassment. Although unlikely due to the extensive 
mitigation measures proposed by Eglin AFB, marine mammals have the 
potential to be killed or injured as a result of a blast due to the 
response of air cavities in the body, such as the lungs and bubbles in 
the intestines. Effects are likely to be most severe in near surface 
waters where the reflected shock wave creates a region of negative 
pressure called ``cavitation.'' This is a region of near total physical 
trauma within which no animals would be expected to survive. A second 
criterion used by NMFS for categorizing taking by mortality is the 
onset of extensive lung hemorrhage. Extensive lung hemorrhage is 
considered to be debilitating and thereby potentially fatal. 
Suffocation caused by lung hemorrhage is likely to be the major cause 
of marine mammal death from underwater shock waves.
    For the acoustic analysis, the exploding charge is characterized as 
a point source. The impact thresholds used for marine mammals relate to 
potential effects on hearing from underwater noise from detonations. 
For the explosives in question, actual detonation heights would range 
from 0 to 25 ft (7.6 m) above the water surface. Detonation depths 
would range from 0 to 80 ft (73.2 m) below the surface. To bracket the 
range of possibilities, detonation scenarios just above and below the 
surface were used to analyze bombs set to detonate on contact with the 
target barge. Potentially, the barge may interact with the propagation 
of noise into the water. However, barge effects on the propagation of 
noise into the water column cannot be determined without in-water noise 
monitoring at the time of detonation.
    Potential exposure of a sensitive species to detonation noise could 
theoretically occur at the surface or at any number of depths with 
differing consequences. As a conservative measure a mid-depth scenario 
was selected to ensure the greatest direct path for the harassment 
ranges, and to give the greatest impact range for the injury 
thresholds.

Explosive Criteria and Thresholds for Impact of Noise on Marine Mammals

    Criteria and thresholds that are the basis of the analysis of PSW 
noise impacts to cetaceans were initially used in U.S. Navy's 
environmental impact statements (EISs) for ship shock trials of the 
SEAWOLF submarine and the USS WINSTON S. CHURCHILL vessel (DON, 1998; 
DON, 2001) and accepted by NMFS as representing the best science 
available (see 66 FR 22450, May 4, 2001). With a single exception 
mentioned in this document, NMFS believes that the criteria developed 
for the shock trials represent the best science available. The 
following sections summarize the information contained in those 
actions.

Criteria and Thresholds: Lethality

    The criterion for mortality for marine mammals used in the 
CHURCHILL Final EIS is 'onset of severe lung injury.' This is 
conservative in that it corresponds to a 1 percent chance of mortal 
injury, and yet any animal experiencing onset severe lung injury is 
counted as a lethal take. The threshold is stated in terms of the 
Goertner (1982) modified positive impulse with value ``indexed to 31 
psi-ms.'' Since the Goertner approach depends on propagation, source/
animal depths, and animal mass in a complex way, the actual impulse 
value corresponding to the 31-psi-ms index is a complicated 
calculation. The acoustic threshold is derived from:
    I1% = 42.9 (M/34)\1/3\ psi-ms,

[[Page 48684]]

    where M is animal mass in kg. Again, to be conservative, CHURCHILL 
used the mass of a calf dolphin (at 12.2 kg), so that the threshold 
index is 30.5 psi-ms.

Criteria and Thresholds: Injury (Level A Harassment)

    Non-lethal injurious impacts are defined in this document as 
eardrum rupture (i.e., tympanic-membrane (TM) rupture) and the onset of 
slight lung injury. These are considered indicative of the onset of 
injury. The threshold for TM rupture corresponds to a 50 percent rate 
of rupture (i.e., 50 percent of animals exposed to the level are 
expected to suffer TM rupture); this is stated in terms of an EFD value 
of 1.17 in-lb/in\2\, which is about 205 dB re 1 microPa\2\-s. (Note: 
EFD is the time integral of the squared pressure divided by the 
impedance in values of dB re 1 microPa\2\-s.) This recognizes that TM 
rupture is not necessarily a life-threatening injury, but is a useful 
index of possible injury that is well-correlated with measures of 
permanent hearing impairment (e.g., Ketten (1998) indicates a 30 
percent incidence of permanent threshold shift (PTS) at the same 
threshold).

Criteria and Thresholds: Non-injurious Impacts (Level B Harassment)

    Marine mammals may also be harassed due to noise from PSW missions 
involving high explosive detonations in the EGTTR. The CHURCHILL 
criterion for non-injurious harassment from detonations, as established 
through NMFS' incidental take rulemaking (see 66 FR 22450, May 4, 
2001), is temporary (auditory) threshold shift (TTS), which is a 
slight, recoverable loss of hearing sensitivity (DoN, 2001). The 
criterion for TTS used in this document is 182 dB re 1 microPa\2\-s 
maximum EFD level in any 1/3-octave band at frequencies above 100 Hz 
for all toothed whales (e.g., sperm whales, beaked whales, dolphins). 
(Note: 1/3-octave band is the EFD in a 1/3-octave frequency band; the 
1/3 octave selected is the hearing range at which the affected species' 
hearing is believed to be most sensitive.) A 1/3-octave band above 10 
Hz is used for impact assessments on all baleen whales, but those 
species do not inhabit the affected environment of this project.
    The CHURCHILL rulemaking also established a second criterion for 
estimating TTS threshold: 12 psi. The appropriate application of this 
second TTS criterion is currently under debate, as this 12-psi 
criterion was originally established for estimating the impact of a 
10,000-lb (4536-kg) explosive to be employed for the Navy's shock 
trial. It was introduced to provide a more conservative safety zone for 
TTS when the explosive or the animal approaches the sea surface (for 
which cases the explosive energy is reduced but the peak pressure is 
not).
    For large explosives (2000 to 10,000 lbs (907-4536 kg)) and 
explosives/animals not too close to the surface, the TTS impact zones 
for these two TTS criteria are approximately the same. However, for 
small detonations, some acousticians contend the ranges for the two TTS 
thresholds may be quite different, with ranges for the peak pressure 
threshold several times greater than those for energy. In its 
application, Eglin AFB endorsed an approach, currently being developed 
by the Navy, for appropriately ``scaling'' the peak pressure threshold, 
in