Taking and Importing Marine Mammals; Taking Marine Mammals Incidental to Conducting Air-to-Surface Gunnery Missions in the Gulf of Mexico, 27695-27710 [06-4436]

Agencies

• DEPARTMENT OF COMMERCE
• National Oceanic and Atmospheric Administration

[Federal Register Volume 71, Number 92 (Friday, May 12, 2006)]
[Notices]
[Pages 27695-27710]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 06-4436]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

[I.D. 031704B]


Taking and Importing Marine Mammals; Taking Marine Mammals 
Incidental to Conducting Air-to-Surface Gunnery Missions 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 conducting air-to-surface (A-S) gunnery missions in the 
Gulf of Mexico (GOM) has been issued to Eglin Air Force Base (Eglin 
AFB) for a period of 1 year.

DATES: Effective from May 3, 2006, through May 2, 2007.

ADDRESSES: The authorization and application containing a list of the 
references used in this document may be obtained 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 20910-3226 or by telephoning the 
contact listed here (see FOR FURTHER INFORMATION CONTACT). The 
application and the Final Programmatic Environmental Assessment (Final 
PEA) is also available at: https://www.nmfs.noaa.gov/pr/permits/
incidental.htm. A paper copy of the Final PEA 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.

FOR FURTHER INFORMATION CONTACT: Kenneth R. Hollingshead, NMFS, 301-
713-2289, 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 marine mammals by U.S. citizens who engage in a 
specified activity (other than

[[Page 27696]]

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.
    Permission may be granted if NMFS finds that the taking will have a 
negligible impact on the species or stock(s) and 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.''
    Subsection 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 MMPA definition of ``harassment'' for ``military 
readiness activities'' is:
    (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 13, 2003, Eglin AFB petitioned NMFS for an 
authorization under section 101(a)(5) of the MMPA for the taking, by 
harassment, of marine mammals incidental to programmatic mission 
activities within the Eglin Gulf Test and Training Range (EGTTR). The 
EGTTR is described as the airspace over the Gulf of Mexico that is 
controlled by Eglin AFB; this area is also sometimes referred to as the 
``Eglin Water Range.'' A decision was made by NMFS to process an IHA 
under section 101(a)(5)(D) for the first year because an IHA can be 
issued more quickly, allowing MMPA coverage for Eglin AFB to be 
followed by rulemaking under section 101(a)(5)(A) of the MMPA for a 5-
year period.
    The A-S gunnery test and training activities currently comprise the 
majority of Eglin's missions that deploy ordnance into the GOM and have 
been determined through a review under the National Environmental 
Policy Act (NEPA) to be the only activity to impact marine mammals 
(Eglin AFB, 2002). The effects of other components of the mission 
activities, including supersonic and subsonic noise from aircraft, 
occasional fuel releases, debris, the release of chemicals into the 
water from chaff, flares, drones, and missiles, and direct physical 
impacts (discussed later in this document) were determined not to 
impact marine mammals (Eglin AFB, 2002).

Description of Activities

    A-S gunnery missions, a ``military readiness activity,'' involve 
surface impacts of projectiles and small underwater detonations with 
the potential to affect cetaceans that may potentially occur within the 
EGTTR. These missions typically involve the use of 25-mm (0.98 in), 40-
mm (1.57 in), and 105-mm (4.13 in) gunnery rounds containing, 0.0662 lb 
(1.1 oz 30 g), 0.865 (13.8 oz, 392 g), and 4.7 lbs (2.1 kg) of 
explosive, respectively. Live rounds must be used to produce a visible 
surface splash that must be used to ``score'' the round; the impact of 
inert rounds on the sea surface would not be detected. The Air Force 
has developed a 105-mm training round (TR) that contains less than 10 
percent of the amount of explosive material (0.35 lb; 0.16 kg) as 
compared to the ``Full-Up'' (FU) 105-mm (4.13 in) round. The TR was 
developed as one method to mitigate effects on marine life during 
night-time A/S gunnery exercises when visibility at the water surface 
would be poor. However, the TR cannot be used in daytime since the 
amount of explosive material is insufficient to be detected from the 
aircraft.
    Water ranges within the EGTTR that are typically used for the 
gunnery operations are located in the GOM offshore from the Florida 
Panhandle (areas W-151A, W-151B, W-151C, and W-151D as shown in Figure 
1 in Eglin's application). Data indicates that W-151A was the most 
frequently used water range due to its proximity to Hurlburt Field, but 
activities may occur anywhere within the EGTTR.
    The AC-130 gunship aircraft normally transit from Hurlburt Field, 
FL to the water range at a minimum of 4,000 ft (1.2 km) above surface 
level. The AC-130 conducts at least two complete orbits at a minimum 
safe airspeed around a prospective target area at a maximum altitude of 
1,500 ft (457 m), with an NMFS recommended altitude of 1,000 ft (305 
m), spiraling in an upward formation to an operational altitude of 
approximately 4,500 to 10,000 ft (1372-3048 m). Ascent occurs over a 
10-15 minute period. Eglin notes that the search area for these orbits 
ensures that no vessels or protected species are within an area of 5-nm 
(9.3 km) of the target. The AC-130 continues orbiting the selected 
target point as it climbs to the mission-testing altitude. During the 
low altitude orbits and the climb to testing altitude, aircraft crew 
visually scan the sea surface within the aircraft's orbit circle for 
the presence of marine vessels and protected species. Primary 
responsibility for the surface scan is on the flight crew in the 
cockpit and personnel stationed in the tail observer bubble and 
starboard viewing window. The AC-130's optical and electronic sensors 
will also be employed for target clearance. If any marine mammals are 
detected within the AC-130's orbit circle, either during initial 
clearance or after commencement of live firing, the aircraft will 
relocate to another target area and repeat the clearance procedures. A 
typical distance from the coast for this activity is at least 15 mi (24 
km).
    When offshore, the crews can scan a 5-nm (9.3-km) radius around the 
potential impact area to ensure it is clear of surface craft, marine 
mammals, and sea turtles. Scanning is accomplished using radar, all-
light television (TV), infrared sensors (IR), and visual means. An 
alternative area would be selected if any cetaceans or vessels were 
detected within a 5-nm (9.3 km) search area. Once the scan is 
completed, Mk-25 flares are dropped and the firing sequence is 
initiated.
    A typical gunship mission lasts approximately 5 hours without 
refueling and 6 hours when air-to-air refueling is accomplished. A 
typical mission includes: (1) 30 minutes for take off and to perform 
airborne sensor alignment, align electro-optical sensors (IR and TV) to 
heads-up display; (2) 1.5 to 2 hours of dry fire (no ordnance 
expended), and includes transition time; (3) 1.5 to 2 hours of live 
fire, and includes clearing the area and transiting to and from the 
range (actual firing activities typically do not exceed 30 minutes); 
(4) 1 hour air-to-air refueling, if and when performed; and (5) 30 
minutes of transition work (take-offs, approaches, and landings-pattern 
work).
    The guns are fired during the live-fire phase of the mission. The 
actual firing can last from 30 minutes to 1.5 hours but is typically 
completed in 30 minutes. The number and type of A-S gunnery munitions 
deployed during a mission varies with each type of mission flown. In 
addition to the 25-, 40-, and 105-mm rounds, marking flares are also 
deployed as targets. All guns are fired at a specific target in the 
water, usually an Mk-25 flare, starting

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with the lowest caliber ordnance or action with the least impact and 
proceeding to greater caliber sizes. To establish the test target area, 
two Mk-25 flares are deployed into the center of the 5-nm (9.3-km) 
radius cleared area (visually clear of aircraft, ships, and surface 
marine species) on the water's surface. The flare's burn time normally 
lasts 10 to 20 minutes but could be much less if actually hit with one 
of the ordnance projectiles; however, some flares have burned as long 
as 40 minutes. Live fires are a continuous event with pauses during the 
firing usually well under a minute and rarely from 2 to 5 minutes. 
Firing pauses would only exceed 10 minutes if surface boat traffic or 
marine protected species caused the mission to relocate; if aircraft, 
gun, or targeting system problems existed; or if more flares needed to 
be deployed. The Eglin Safety Office has described the gunnery missions 
as having 95-percent containment with a 99-percent confidence level 
within a 5-m (16.4-ft) area around the established flare target test 
area.

Live-fire Event: Phase I: 10 minutes

    The 25-mm (0.98-in) round is fired first. The 25-mm firing event in 
a typical mission includes approximately 500 to 1000 rounds. These 
rounds are first in short bursts. These bursts last approximately 2-3 
seconds with approximately 100 rounds per burst. Based on the very 
tight target area and extremely small miss distance, these bursts of 
rounds all enter the water within a 5-m (16.4-ft) area. Therefore, when 
calculations of the marine mammal Zone of Impact (ZOI) and take 
estimates are made later in this document for the 25-mm rounds, 
calculations will be based on the total number of rounds fired per year 
divided by 100.

Live-fire Event: Phase II: 10 minutes

    The 40-mm (1.57 in) round is fired second. The 40-mm firing event 
of a typical mission includes approximately 10 seconds with 
approximately 20 rounds per burst. Based on the very tight target area 
and extremely small miss distance, these bursts of rounds all enter the 
water within a 5-m (16.4 ft) area. Therefore, when calculations of the 
marine mammal ZOI and take estimates are made later in this document 
for the 40-mm rounds, calculations will be based on the total number of 
rounds fired per year divided by 20.

Live-fire Event: Phase III: 10 minutes

    The 105-mm round is fired last. The 105-mm firing event of a 
typical mission includes approximately 20 rounds. These rounds are not 
fired in bursts, but as single shots. The 105-mm firing event lasts 
approximately 5 minutes with approximately two rounds per minute. Due 
to the single firing event of the 105-mm round, the peak pressure of 
each single 105-mm round is measured at a given distance (90 m (295 
ft)) for the 105mm TR and 216 m (709 ft) for the 105mm FU).
    As described in Eglin's application, gunnery testing in this 
request includes historical baseline yearly amounts in addition to 
proposed nighttime gunnery missions. Daytime gunnery testing uses the 
105-mm FU round and nighttime gunnery training is proposed using the 
105-mm TR. The number of 105-mm rounds including nighttime operations 
would amount to 1,742. As shown in detail in Tables 1 and 2, Eglin 
proposes to conduct a total of 28 daytime missions and 263 nighttime 
missions annually, expending 3,832 rounds in daytime and 30,802 rounds 
nighttime (242 105-mm FU and 1,500 rounds would be the 105-mm TR).

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Comments and Responses

    A notice of receipt of Eglin's application for an incidental take 
authorized under section 101(a)5)(A) of the MMPA and request for 30-day 
public comment on both that application and the proposed IHA was 
published on January 23, 2006 (71 FR 3474). During the 30-day public 
comment period, NMFS received comments from the Marine Mammal 
Commission (the Commission) and three members of the public.
    Comment 1: Comments expressed concern that marine life in the Gulf 
is already stressed due to pollution and other anthropogenic sources. 
These commenters recommended the IHA be denied.
    Response: Section 101(a)(5) of the MMPA requires the Secretary to 
issue incidental harassment authorizations provided, among other 
things, a determination has been made that the taking by the activity 
will not have more than a negligible impact on the affected species or 
stock of marine mammals. As these determinations have been made here 
(see later in this document), issuance of the IHA is warranted.
    Also, it should be recognized that A-S gunnery exercises will 
impact an area less than 500 m (1640 ft) in diameter when using the 
105-mm (FU) round, the largest charge. Impacts at this distance will be 
limited to Level B (behavioral) harassment. This is an extremely small 
area of the northern Gulf of Mexico and is, therefore, unlikely to 
result in long-term cumulative impacts as noted in Eglin's PEA.
    Comment 2: The Commission believes that the statutory change to the 
definition of harassment in the MMPA resulting from implementation of 
Public Law 108-136, the National Defense Authorization Act for Fiscal 
Year 2004 cannot be ignored. The Commission recommends that NMFS 
analyze the request for incidental harassment authorization and the 
incidental take regulations being contemplated in light of the more 
recent applicable definition of harassment.
    Response: The preamble to the notice of proposed authorization and 
this document cite the definition of harassment for military readiness 
activities. An authorization under section 101(a)(5) of the MMPA is 
warranted because some animals may be harassed either by incurring a 
temporary elevation in hearing sensitivity or through a behavioral 
change if the mitigation and monitoring overlooks an animal. This is 
especially true for night-time exercises, where visual detection 
ability will be poor.
    Comment 3: The Commission remains concerned that the proposed 
monitoring and mitigation measures, particularly during night-time 
activities, will not be sufficient to ensure that marine mammals are 
not being taken in unanticipated ways or numbers. NMFS should provide 
its assessment of the likelihood of detecting marine mammals at or 
below the surface within zones of potential impacts, particularly when 
operations are occurring at night or under foggy conditions.
    Response: As a preliminary matter, NMFS does not believe marine 
mammals below the water surface are likely to incur more than Level B 
harassment because marine mammals should be detectable by means other 
than visual; rounds contain either no or relatively small amounts of 
explosive (therefore, very small Level A harassment impact zones (see 
Table 11 later in this document); and, detonations at the water surface 
vent most of their energy into the air, not into the water column. 
However, we recognize this activity could potentially injure or kill 
marine mammals and sea turtles at the surface by falling debris, 
projectiles, small arms and live-fire gunnery operations (if not 
sighted and firing discontinued). Therefore, mitigation and monitoring 
needs to be effective for detecting animals at the water surface. Table 
3 lists the general likelihood of detection of the marine mammal 
species under consideration. The categories of high, moderate, and low 
are relative in terms of the varying attributes among the species, and 
it is acknowledged that observation of any species is more difficult at 
night or in unfavorable weather conditions. However, because the zone 
for Level A impacts is small (see Table 11 later in this document), 
marine mammals not at the water surface are unlikely to incur more than 
Level B harassment.
    During night-time operations, when visual detection will be poor, 
all-light TV and IR sensors will be used to survey for marine mammals 
during the AC-130's ascending orbits and during live-fire events. It is 
possible, though not well documented, that surfaced cetaceans can be 
detected by IR sensors due to the heat radiating from the animals' 
bodies (particularly dorsal fins), especially those species that are 
large or which tend to occur in large groups. Moreover, the zone for 
marine mammal Level A harassment impacts is small. Therefore, while the 
Air Force cannot visually detect marine mammals at night, the use of 
other instrumentation (particularly IR sensors for detecting 
cetaceans), combined with the small Level A Harassment zones, low 
species abundance, and use of the 105-mm TR, is expected to prevent 
marine mammal and sea turtle mortality.
    Comment 4: In regard to monitoring, the Commission believes NMFS 
and Eglin have not provided, but should provide, information concerning 
the time it takes the AC-130 flying at ``minimum safe speed'' to 
accomplish two orbits and how that time compares with the dive times of 
various marine mammal species. Additional information on which species 
can be detected at which altitudes particularly when operations are 
occurring at night or in fog is needed because most of the exercises 
will be at night.
    Response: Aircrews will initiate the pre-mission clearance 
procedures at an altitude no higher than 1,500 ft (457 m)(via two 
orbits), and spiral up to the operational altitude of approximately 
4,500 to 10,000 ft (1372 to 3048 m). Based on consultation with air 
crew personnel, the two-orbit ascent will occur over a 10- to 15-minute 
time frame, depending upon the terminal altitude.
    General maximum dive times, as well as likelihood of detection and 
likelihood of occurrence in training areas, for all 16 marine mammal 
species authorized under the IHA are listed in Table 3. The AC-130 
ascent time reasonably spans the dive time of 10 of these species. Of 
the remaining species, none are considered to have a high likelihood of 
occurring in potential mission areas.

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    Comment 5: The Commission believes that NMFS needs to explain more 
clearly its determinations with respect to the dual criteria being used 
to establish the proposed zones. Specifically, NMFS should clarify why 
the proposed zone of impact for behavioral disruption (22.1 m (72.5 
ft)) based on a 176-dB (SEL) threshold) is considerably smaller than 
the zone of impact for TTS using the 23-psi criteria (216 m (709 ft)). 
Under these criteria, using 105-mm ``full up'' ordnance, NMFS has 
determined that up to 217 marine mammals could experience TTS, whereas 
only 25 marine mammals could experience behavioral disturbance (without 
TTS). The Commission notes that, as recognized under the other aspect 
of the dual criteria for TTS (182 dB), one would generally expect the 
threshold for behavioral modification to be lower than that causing 
TTS. Thus, it is not clear why an alternate, more conservative 
criterion, is not also being proposed for behavioral modification. NMFS 
should explain this apparent contradiction.
    Response: NMFS adopted a dual criterion for TTS Level B harassment 
during rulemakings for the Navy ship-shock trials. NMFS has not adopted 
a dual criterion for non-TTS behavioral responses by marine mammals. A 
TTS pressure criterion was added during the shock trial rulemaking (see 
87 FR 22450, May 4, 2001) to provide a more conservative zone for 
calculating potential TTS exposures when the explosive or the animal 
approaches the sea surface (for which cases the explosive energy is 
reduced but the peak pressure is not). Originally established at 12 psi 
for large charges (such as in the 10,000 lb (4536 kg) shock trials), 
empirical research now supports a pressure metric of 23 psi, as 
explained previously (see 70 FR 48675, August 19, 2005). The 23-psi 
metric for onset TTS has been adopted by NMFS for this action. 
Explanation is provided elsewhere in this document (as in the proposed 
IHA notice) on NMFS' incorporation of 176 dB (SEL) for calculating 
behavioral responses below TTS. Therefore, while NMFS agrees with the 
Commission that one would generally expect the threshold for behavioral 
modification to be lower than that causing TTS, due to a lack of 
empirical information and data, a dual criteria for Level B behavioral 
harassment cannot be developed, and any number chosen by NMFS at this 
time, would be arbitrary. NMFS plans to investigate this situation 
during the development of a proposed rule on this action and will 
provide the Commission and the public additional information at that 
time.
    Comment 6: The Commission notes that NMFS plans to require that, if 
any marine mammal or sea turtle is observed or otherwise detected prior 
to testing, or if any marine mammal or sea turtle is injured or killed 
during live fire, a report must be made to NMFS by the following 
business day. The Commission recommends that, in addition to requiring 
that such incidents be reported, NMFS require that operations be 
suspended immediately if a dead or seriously injured marine mammal is 
found in the vicinity of the operations and the death or injury could 
have occurred incidental to the gunnery activities. Any such suspension 
should remain in place until NMFS has (1) reviewed the situation and 
determined that further mortalities or serious injuries are unlikely to 
occur or (2) issued regulations authorizing such takes under section 
101(a)(5)(A) of the Act.
    Response: As noted in previous Federal Register notices, activity 
suspension is a standard condition on all IHAs whenever it appears an 
unauthorized taking may have occurred.
    Comment 7: The Commission notes that of the 29 species of marine 
mammals documented to occur within the Gulf of Mexico, Eglin AFB is 
requesting authority to take 21 species incidental to the proposed 
activities. It is not readily apparent why at least some of the other 
species that are known to occur in the Gulf might not also be taken. 
These species include the endangered right, humpback, fin, sei, and 
blue whales. Although some of these species may be rarely sighted, they 
are known to occur in or near the Eglin Gulf Test and Training Range. 
As such, NMFS and/or Eglin AFB should either amend the application to 
include these other species in the authorization or provide additional 
explanation as why these species are being excluded.
    Response: There are several reasons for not including these 
cetacean species in Eglin AFB's authorized list of species for taking 
by Level B harassment: (1) Most A-S gunnery exercises take place on 
shelf waters, which large cetaceans do not inhabit; (2) the northern 
right whale, which is more coastal, is extremely rare in the northern 
Gulf; (3) the rarity of ESA-listed species makes them unlikely to be 
affected even without mitigation and monitoring, as shown in Tables 4, 
5, 6 and 7; and (4) the relatively shallow water on the continental 
shelf and large size make these species readily detectable by visual 
and electronic detection from the AC-130 aircraft. This finding is 
consistent with the finding by NMFS' Southeast Region's October 20, 
2004 Biological Opinion.
    Comment 8: The Commission also reiterates its view that an across-
the-board definition of TTS as constituting no more than level B 
harassment inappropriately dismisses possible injury and biologically 
significant behavioral effects to the affected animals that may occur 
if an animal's hearing is compromised, even temporarily.
    Response: NMFS has provided detailed response to the scientific 
basis for considering TTS to be Level B harassment and not Level A 
harassment (injury). Reviewers are encouraged to read these documents 
for additional information (70 FR 48675, August 19, 2005; 66 FR 22450, 
May 4, 2001). However, since TTS is considered Level B harassment, and 
significant behavioral effects that result from TTS are also considered 
Level B harassment takes, the significant behavioral response is 
included in the incidental take calculations. In addition, unlike the 
cited previous actions, which were single detonations, A-S gunnery 
exercises result in multiple detonations. As a result, behavioral 
reactions to the noise itself are included in the take estimate 
calculations (as shown in Table 12 later in this document).

Description of Marine Mammals Affected by the Activity

    There are 29 species of marine mammals documented as occurring in 
Federal waters of the GOM. General information on these species can be 
found in Wursig et al. (2000) and in the NMFS Stock Assessment Reports 
(Waring et al., 2004). This latter document is available at: https://
www.nefsc.noaa.gov/nefsc/publications/tm/tm182/
 Of these 29 species of marine mammals, approximately 21 may be 
found within the EGTTR. These species are the Bryde's whale, sperm 
whale, dwarf sperm whale, pygmy sperm whale, Atlantic bottlenose 
dolphin, Atlantic spotted dolphin, pan-tropical spotted dolphin, 
Blainville's beaked whale, Cuvier's beaked whale, Gervais' beaked 
whale, Clymene dolphin, spinner dolphin, striped dolphin, killer whale, 
false killer whale, pygmy killer whales, Risso's dolphin, Fraser's 
dolphin, melon-headed whale, rough-toothed dolphin, and pilot whale. 
Supplementary information on those species that may be impacted by the 
A/S gunnery exercises are discussed in the Eglin application (Eglin 
AFB, 2003) and the Eglin's Final PEA.

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Potential Impacts to Marine Mammals

    A/S gunnery operations may potentially impact marine mammals at the 
water surface. Marine mammals could potentially be harassed, injured or 
killed by exploding and non-exploding projectiles, and falling debris 
(Eglin, 2002 (Final PEA)). However, based on analyses provided in the 
Eglin Final PEA and in Eglin's Supplemental Information Request 
(2003)), NMFS concurs with Eglin that gunnery exercises are not likely 
to result in any injury or mortality to marine mammals.
    Explosive criteria and thresholds for assessing impacts of 
explosions on marine mammals were discussed by NMFS in detail in its 
issuance of an IHA for Eglin's Precision Strike Weapon testing activity 
(70 FR 48675, August 19, 2005) and are not repeated here. Please refer 
to that document for background information.

Estimation of Take and Impact

Direct Physical Impacts (DPI)

    Potential impacts resulting from air-to-surface test operations 
include DPI resulting from ordnance. DPI could result from inert bombs, 
gunnery ammunition, and shrapnel from live missiles falling into the 
water. Marine mammals and sea turtles swimming at the surface could 
potentially be injured or killed by projectiles and falling debris if 
not sighted and firing discontinued. Small arms gunnery operations may 
offer a worst case scenario for evaluating DPI of EGGTR operations, 
mainly due to the comparatively large number of rounds expended. Some 
contain small amounts of explosives, but the majority do not. The 
assumptions made by Eglin for DPI calculations can be found in Eglin's 
Final PEA under Alternative 1 for this action. Approximately 606 small-
arms gunnery firing events comprise the estimated level of potential 
DPI events, as shown in Table 4.
    DPI impacts are anticipated to affect only marine species at or 
very near the ocean surface. As a result, to calculate impacts, Eglin 
used corrected species densities (Table 4-23 in Eglin's Final PEA) to 
reflect the surface interval population, which is approximately 10 
percent of densities calculated for distribution in the total water 
column. As shown in Table 5 of this document (and correcting PEA Table 
4-23), the impacts to marine mammals and sea turtles at the surface 
that could potentially be injured or killed by projectiles and falling 
debris was determined to be very low, and mitigation measures that 
Eglin will employ under this action would reduce even these low levels.
    In addition to small arms, Eglin calculated the potential for other 
non-explosive items (inert bombs, missiles, and drones) to impact 
marine mammals and sea turtles. The number of annual events expected 
are 551 bombs, 1183 missiles, and 99 drones (Table 6). As shown in 
Eglin's Final PEA and Table 7 in this document, the potential for any 
DPI to marine mammals and sea turtles is extremely remote and can, 
therefore, be discounted.

     Table 4. Air-to-Surface Gunnery/Small Arms Operations as Events
------------------------------------------------------------------------
    Activity Description of EGTTR Events       Percentage      Number
------------------------------------------------------------------------
       Small Arms .50 Cal Ball Events               16.3%            99
        Small Arms 5.56 Linked Events                0.8%             5
       Small Arms 7.62 mm Ball Events               82.8%           502
Total Baseline EGTTR Air-to-Surface Gunnery/       100.0%           606
            Small Caliber Events
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                  Table 5. Potential Small Arms DPI Impacts (Annual) to Marine Mammal Species.
----------------------------------------------------------------------------------------------------------------
                                                                Adjusted                               Years to
                                                   Density      Density    Impact Zone   Animals in    Impact 1
                    Species                      (/  (/    Area\1\    Impact Zone     Animal
                                                    km\2\        km\2\)      (km\2\)    ()  ()
----------------------------------------------------------------------------------------------------------------
                   Cetaceans                           4.381       0.4381     0.047874     2.10E-02           48
                 T&E Cetaceans                         0.011       0.0011     0.047874     5.27e-05       18,989
                  Sea Turtles                          0.869       0.0869     0.047874     4.16E-03          240
----------------------------------------------------------------------------------------------------------------


              Table 6. Non-Small Arms Operations as Events
------------------------------------------------------------------------
     Activity Description of EGTTR Events        Percentage     Number
------------------------------------------------------------------------
                     Bombs                            30.1%          551
                   Missiles                           64.5%         1183
                    Drones                            5.4 %           99
  Total Baseline EGTTR Non-Small Arms Events         100.0%         1833
------------------------------------------------------------------------


              Table 7. Potential Non-Small Arms/Non-Gunnery DPI Impacts (annual) to Marine Species
----------------------------------------------------------------------------------------------------------------
                                                       Adjusted                                        Years to
                                          Density      Density    Impact Zone    Animals in Impact     Impact 1
                Species                 (/  (/    Area\1\      Zone ()       Animal
                                           km\2\        km\2\)      (km\2\)                          ()
----------------------------------------------------------------------------------------------------------------
               Cetaceans                      4.381       0.4381      0.00688           0.003014128          332
             T&E Cetaceans                    0.011       0.0011      0.00688           0.000007568      132,135
              Sea Turtles                     0.869       0.0869      0.00688           0.000597872       21,673
----------------------------------------------------------------------------------------------------------------


[[Page 27703]]

    Similar to non-gunnery/non-small arms DPI impacts, DPI impacts from 
gunnery activities may also affect marine mammals and sea turtles in 
the surface zone. Again, DPI impacts are anticipated to affect only 
marine species at or near the ocean surface. Accordingly, the density 
estimates have been adjusted to indicate surface animals only being 
potentially affected. Using the firing methodology explained earlier in 
this document, Tables 8 and 9 demonstrate that the potential for any 
DPI from gunnery activities are extremely remote and can be discounted.

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[[Page 27705]]

Marine Mammal Take Estimates from Gunnery Activities

    Estimating the impacts to marine mammals from underwater 
detonations is difficult due to complexities of the physics of 
explosive sound under water and the limited understanding with respect 
to hearing in marine mammals. The assessments made in this document 
use, and improve upon, the criteria and thresholds for marine mammal 
impacts that were developed for the shock trials of the USS SEAWOLF 
submarine and the destroyer USS Winston S. Churchill (DDG-81) (Navy, 
1998; 2001). The criteria and thresholds used in those documents were 
adopted by NMFS for use in calculating incidental takes from 
explosives. Criteria for assessing impacts include: (1) Mortality, as 
determined by exposure to a certain level of positive impulse pressure 
(expressed as pounds per square inch per millisecond or psi-msec); (2) 
injury, both hearing-related and non-hearing related; and (3) 
harassment, as determined by a temporary loss of some hearing ability 
and behavioral reactions. Due to the small amounts of net explosive 
weight (NEW) for each of the rounds fired in the EGTTR and the 
mitigation measures, mortality resulting from sounds generated in the 
water column was determined to be highly unlikely and is not considered 
further.
    Permanent hearing loss is considered an injury and is termed 
permanent threshold shift (PTS). NMFS, therefore, categorizes PTS as 
Level A harassment. Temporary loss of hearing ability is termed a 
temporary threshold shift (TTS), meaning a temporary reduction of 
hearing sensitivity which abates following noise exposure. TTS is 
categorized as a Level B type of harassment and is considered non-
injurious. NMFS recognizes dual criteria for TTS, one based on peak 
pressure and one based on the greatest 1/3 octave sound exposure level 
(SEL) or energy flux density level (EFDL), with the more conservative 
(i.e., larger) of the two criteria being selected for impacts analysis 
(note: SEL and EFDL are used interchangeably, but with increasing 
scientific preference for SEL). The peak pressure metric used in the 
shock trials to represent TTS was 12 pounds per square inch (psi) 
which, for the NEW used, resulted in a zone of possible Level B 
harassment approximately equal to that obtained by using a 182 decibel 
(dB) re 1 micro Pa2-s, total EFDL/SEL metric. The 12-psi metric is 
largely based on anatomical studies and extrapolations from terrestrial 
mammal data (see Ketten, 1995; Navy, 1999 (Appendix E, Churchill FEIS; 
and 70 FR 48675 (August 19, 2005)) for background information). 
However, the results of a more recent investigation involving marine 
mammals suggest that, for charges considerably smaller than those used 
in the Navy shock trials, the 12-psi metric is not an adequate 
predictor of the onset of TTS.
    Finneran et al. (2002) measured TTS in a bottlenose dolphin and a 
beluga whale exposed to single underwater impulses produced by a 
seismic water gun in San Diego Bay. The water gun was chosen over other 
seismic sources, such as air guns, because the impulses contain more 
energy at high frequencies where odontocete hearing thresholds are 
relatively low (i.e., more sensitive). Hearing thresholds were measured 
at 0.4, 4, and 30 kilohertz (kHz). A relatively small and short-term 
level of masked TTS (MTTS)(7 dB at 0.4 kHz and 6 dB at 30 kHz) occurred 
in the beluga whale at a peak pressure of 160 kilopascals (kPa), which 
is equivalent to 23 psi, 226 dB re 1 micro Pa peak-peak pressure, and 
186 dB re 1 microPa\2\-s. The maximum experimental peak pressure 
exposure of 207 kPa (30 psi, 228 dB re 1 microPa peak-peak pressure, 
188 dB re 1 microPa\2\-s) did not cause any measurable masked TTS in 
the bottlenose dolphin. The results of these field experiments 
represent the most current science available for the relationship 
between peak pressure and TTS in marine mammals. It is also considered 
precautionary for this project since the bottlenose dolphin did not 
incur an MTTS at the higher level of 30 psi. Therefore, until 
additional information becomes available, 23 psi is considered an 
appropriate and conservative metric for predicting the onset of 
pressure-related TTS from small explosive charges.
    Documented behavioral reactions occur at noise levels below those 
considered to cause TTS in marine mammals (Finneran et al., 2002; 
Schlundt et al., 2000; Finneran and Schlundt, 2004). In controlled 
experimental situations, behavioral effects are typically defined as 
alterations of trained behaviors. Behavioral effects in wild animals 
are more difficult to define but may include decreased ability to feed, 
communicate, migrate, or reproduce. Abandonment of an area due to 
repeated noise exposure is also considered a behavioral effect. 
Analyses in subsequent sections of this document refer to such 
behavioral effects as ``sub-TTS Level B harassment.'' Schlundt et al. 
(2000) exposed bottlenose dolphins and beluga whales to various pure-
tone sound frequencies and intensities in order to measure underwater 
hearing thresholds. Masking is considered to have occurred because of 
ambient noise environment in which the experiments took place. Sound 
levels were progressively increased until behavioral alterations were 
noted (at which point the onset of TTS was presumed). It was found that 
decreasing the sound intensity by 4 to 6 dB greatly decreased the 
occurrence of anomalous behaviors. The lowest sound pressure levels, 
over all frequencies, at which altered behaviors were observed, ranged 
from 178 to 193 dB re 1 micro Pa for the bottlenose dolphins and from 
180 to 196 dB re 1 micro Pa for the beluga whales. Thus, it is 
reasonable to consider that sub-TTS (behavioral) effects occur at 
approximately 6 dB below the TTS-inducing sound level, or at 
approximately 176 dB in the greatest 1/3 octave band EFDL/SEL.
    Table 10 summarizes the relevant thresholds (summarized from 
information in 70 FR 48675 (August 19, 2005) and in this document), 
which are specified levels of noise that may result in injury, TTS or 
behavioral harassment to marine mammals. Mortality and injury 
thresholds are designed to be conservative by considering the impacts 
that would occur to the most sensitive life stage (e.g., a dolphin 
calf). Table 11 provides the estimated ZOI radii for the EGTTR 
ordnance.
    At this time, there is no empirical data or information that would 
allow NMFS to establish a peak pressure criterion for sub-TTS 
behavioral disruption.

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[[Page 27707]]

    As mentioned previously, the EGTTR live fire events are continuous 
events with pauses during the firing usually well under a minute and 
rarely from 2 to 5 minutes. Live fire typically occurs within a 30 
minute time frame, including all ordnance fired: 25-mm (Phase I), 40-mm 
(Phase II), and 105-mm (Phase III), and where the 105-mm ordnance are 
fired as separate rounds with up to 30-second intervals, the 25-mm and 
the 40-mm are often fired in multiple bursts. These burst include 
multiple rounds (25 to 100) within a 10- to 20-second time frame. Eglin 
notes that even if the avoidance concept of animals evading the area 
once firing commences is not considered, an average swim speed (1.5 m/
s) of animals would not allow sufficient time for new animals to re-
enter the Level B harassment ZOI (23 psi) within the time frame of a 
single burst. As such, only the peak pressure of a single round is 
measured per burst and experienced at a given distance (49 m (161 ft; 
Phase I), 122 m (400 ft; Phase II)).
    For daytime firing it is assumed that the average swim speed per 
cetacean is approximately 3 knots or 1.5 m/sec. As a conservative 
scenario, Eglin assumes that there is one animal present within or near 
the 216-m ZOI (FU 105-mm round ZOI) which may be potentially ensonified 
within the 23-psi TTS exposure at the time that the 105-mm live firing 
begins. Density distributions have assumed an even distribution (or 
approximately 500 m (1640 ft) apart) of approximately 4.38 animals/km2 
(all species) for the approach of impact analyses for a take 
estimation. At this density distribution and typical swim speed, the 
next available cetacean would approach the perimeter of the 216-m (709 
ft) ZOI (23-psi TTS ZOI) in approximately 5.5 minutes assuming a 
straight line path. With live fire events of the 105-mm occurring at a 
rate of approximately 2 rounds per minute, nearly one half (or 10 
rounds) of the total 105-mm rounds (20 rounds) would potentially be 
expended within this 5.5 minute time frame. If the concept that marine 
mammals will evade an area once firing commences is not considered, an 
average swim speed (1.5 m/s) of animals would allow sufficient time for 
new animals to re-enter the 23-psi TTS impact area. Allowing for a 
potential 2 minute break in firing after 10 rounds are expended, it is, 
therefore, conservative and reasonable to assume that nearly 3 to 4 
individual animals may be potentially exposed to the 23-psi TTS sound 
level during a typical 20 round firing event. Therefore, the ZOI and 
Level B harassment take estimate calculations are based on the total 
number of rounds fired per year divided by 5, or approximately 20 
percent. This approach assumes that although single animals may be 
ensonified more than once due to the time required to exit the 23 psi 
TTS ZOI, animals are not considered to be ``taken'' more than once for 
the purposes of estimating take levels.
    Similarly, as a conservative approach for nighttime firing, Eglin 
assumes that there is one animal present within or near the 90-m (295-
ft) ZOI (105-mm TR ZOI) which may be potentially ensonified within the 
23-psi TTS exposure zone at the time that the 105-mm round live firing 
phase begins. Density distributions have assumed an even distribution 
of approximately 4.38 animals/km\2\ (all species) for the approach of 
impact analyses for estimation of take. At this density distribution 
and typical swim speed, the next available cetacean would approach the 
perimeter of the 90-m (295-ft) ZOI (23-psi TTS ZOI) in approximately 
5.5 minutes or the same time as with the 216-m ZOI (used for the 105-mm 
FU). The difference is the amount of time it takes the animal to exit 
the ZOI or in other words, how long the animals resides within the ZOI 
on a straight line path. With live fire events of the 105-mm round 
occurring at a rate of approximately 2 rounds per minute, nearly one 
half (or 10 rounds) of the total 105-mm rounds (20 rounds) would 
potentially be expended within this 5.5-minute time frame. If the 
concept that marine mammals will evade an area once firing commences is 
not considered, an average swim speed (1.5 m/s) of animals would allow 
sufficient time for new animals to re-enter the 23-psi TTS impact area. 
Allowing for a potential 2-min break in firing after 10 rounds are 
expended, it is conservative and reasonable to assume that nearly 3 to 
4 individual animals may be potentially exposed to the 23-psi TTS sound 
level during a typical 20 round firing event. Therefore, the ZOI and 
take estimate calculations are based on the total number of rounds 
fired per year divided by 5, or approximately 20 percent. This approach 
assumes that, although single animals may be ensonified more than once 
due to the time required to exit the 23-psi TTS ZOI, individual animals 
are not considered to be ``taken'' more than once for the purposes of 
estimating take levels.
    Based on this discussion, Table 12 provides Eglin's estimates of 
the annual number of marine mammals, by species, potentially affected 
by the gunnery mission noise. It should be noted that these estimates 
are derived without consideration of the effectiveness of Eglin's 
proposed mitigation measures (except use of the TR), which are 
discussed next.

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[[Page 27709]]

Mitigation

    Eglin AFB will employ a number of mitigation measures in an effort 
to substantially decrease the number of animals potentially affected. 
Eglin AFB states that it is committed to assessing the mission activity 
for opportunities to provide operational mitigation (i.e., ramping up 
and using nighttime training rounds), while potentially sacrificing 
some mission flexibility.

Visual Mitigation

    Areas to be used in gunnery missions will be visually monitored for 
marine mammal presence from the AC-130 aircraft prior to commencement 
of the mission. If the presence of one or more marine mammals is 
detected, the target area will be avoided. In addition, monitoring will 
continue during the mission. If marine mammals are detected at any 
time, the mission will be either immediately halted and/or relocated as 
necessary or suspended until the marine mammal has left the area. While 
visual monitoring at a height of 1000-1500 ft ((305-457 m), is expected 
to be effective, standard visual monitoring is not very effective at 
10,000 ft (3.0 km) unless there is a large pod of marine mammals. 
Daytime and nighttime visual monitoring will be supplemented with IR 
and TV monitoring. As nighttime visual monitoring is generally 
considered to be ineffective at any height, the EGTTR missions will 
incorporate the TR.

Development of the TR

    The largest type of ammunition used during typical gunnery missions 
is the 105-mm (4.13-in) round containing 4.7 lbs (2.1 kg) of HE. This 
is several times more HE than that found in the next largest round (40 
mm/1.57 in). As a mitigation technique, the Air Force developed a 105-
mm TR that contains only 0.35 lb (0.16 kg) of HE. The TR was developed 
to significantly reduce the effects of nighttime operations, when 
visual surveying for marine mammals is of limited effectiveness. Use of 
the TR at night dramatically reduces the risk of harassment, and Eglin 
anticipates a 96 percent reduction in impact by using the 105-mm TR.

Ramp-Up

    Eglin proposes to ramp-up activities by beginning with the smallest 
round (or the round having least impact) and proceeding to subsequently 
larger size rounds (in this case the lowest caliber of munition up to 
the 105-mm FU round). Theoretically, this allows animals to perceive 
steadily increasing sounds and to react, if necessary. Alerting animals 
in advance of injurious sound waves by transmitting low-power 
``warning'' signals a short time before the action provides a safeguard 
where there is a potential for the risk of injury.

Other Mitigation

    Under this IHA, NMFS is requiring additional measures to protect 
marine life that were originally recommended as part of section 7 
consultations under the Endangered Species Act (ESA) with Eglin. These 
requirements are:
    (1) Test firing will be conducted only when sea surface conditions 
are sea state 3.5 or less on the Beaufort scale.
    (2) Prior to each firing event, the aircraft crew will conduct a 
visual survey of the 5-nm (9.3-km) wide prospective target area to 
attempt to sight any protected species that may be present (e.g., 
marine mammals, sea turtles, and Sargassum rafts). The AC-130 gunship 
will conduct at least two complete orbits at a minimum safe airspeed 
around a prospective target area at a maximum altitude of 1,500 ft (457 
m), with a recommended altitude of 1,000 ft (305 m). Provided protected 
species are not detected, the AC-130 can then continue orbiting the 
selected target point as it climbs to the mission testing altitude. 
During the low altitude orbits and the climb to testing altitude, the 
aircraft crew will visually scan the sea surface within the aircraft's 
orbit circle for the presence of listed and non-listed marine mammals 
and sea turtles. Primary emphasis for the surface scan will be upon the 
flight crew in the cockpit and personnel stationed in the tail observer 
bubble and starboard viewing window. The AC-130's optical and 
electronic sensors will also be employed for target clearance. If any 
marine mammals are detected within the AC-130's orbit circle, either 
during initial clearance or after commencement of live firing, the 
aircraft will relocate to another target and repeat the clearance 
procedures. If multiple firing events occur within the same flight, 
these clearance procedures will precede each event.
    (3) The aircrews of the air-to-ground gunnery missions will 
initiate location and surveillance of a suitable firing site 
immediately after exiting U.S. territorial waters (> 12 nm). This would 
potentially restrict most gunnery activities to the shallower 
continental shelf waters of the GOM where marine mammal densities are 
typically lower, and thus potentially avoid the slope waters where the 
more sensitive species (e.g., endangered sperm whales) typically 
reside.
    (4) Observations will be accomplished using all-light TV, IR 
sensors, and visual means for at least 60 minutes prior to each 
exercise.
    (5) Aircrews will utilize visual, night vision goggles (NVGs), and 
other onboard sensors to search for marine mammals and sea turtles 
while performing area clearance procedures during night-time pre-
mission activities.
    (6) If any marine mammals, sea turtles, or Sargassum rafts are 
sighted during pre-mission surveys or during the mission, activities 
will be immediately halted until the area is clear of all protected 
marine species for 60 minutes or the mission location relocated and 
resurveyed.

Monitoring and Reporting

    The NMFS Biological Opinion on this action recommended certain 
monitoring measures to protect marine life. As a result, NMFS has 
imposed these same requirements under the IHA:
    (1) Eglin will develop and implement a marine species observer-
training program in coordination with NMFS. This program will primarily 
provide expertise to Eglin's testing and training community in the 
identification of protected marine species during surface and aerial 
mission activities in the GOM. Additionally, the A-S gunnery mission 
aircrews will participate in the proposed species observation training. 
As a result, designated crew members will be selected to receive 
training as protected species observers. Observers will receive 
training in protected species survey and identification techniques 
through a NMFS-approved training program.
    (2) Aircrews will initiate the post-mission clearance procedures 
beginning at the operational altitude of approximately 15,000 to 20,000 
ft (4572 to 6096 m) elevation, and initiating a spiraling descent down 
to an observation altitude of approximately 1,500 ft. (457 m) 
elevation. Rates of descent will occur over a 3 to 5 minute time frame.
    (3) Eglin will track their use of the EGTR for test firing missions 
and protected resources (marine mammal/sea turtle) observations, 
through the use of mission reporting forms.
    (4) A-S gunnery missions will coordinate with next-day flight 
activities to provide supplemental post-mission observations for marine 
mammals and sea turtles in the operations area of the previous day.
    (5) A summary annual report of marine mammal/sea turtle 
observations and A-S activities will be submitted to the NMFS Southeast 
Regional Office (SERO) and the Office of Protected Resources either at 
the time of a request for renewal of an IHA or 90 days after

[[Page 27710]]

expiration of the current IHA if a new IHA is not requested.
    (6) If any dead or injured marine mammals or sea turtles are 
observed or detected prior to testing, or injured or killed during live 
fire, a report must be made to the NMFS by the following business day.
    (7) Any unauthorized takes of marine mammals (i.e., injury or 
mortality) must be immediately reported to the NMFS representative and 
to the respective stranding network representative.

ESA

    Consultation under section 7 of the ESA on Eglin EGTTR activities 
was completed on December 18, 1998. Consultation was reinitiated by 
Eglin AFB with NMFS on February 13, 2003 and concluded on October 20, 
2004. A NMFS Biological Opinion issued on October 20, 2004, concluded 
that the A-S gunnery exercises in the EGTTR are unlikely to jeopardize 
the continued existence of species listed under the ESA that are within 
the jurisdiction of NMFS or destroy or adversely modify critical 
habitat. NMFS has determined that issuance of an IHA to Eglin AFB for 
this activity will not have effects beyond what was analyzed in 2004 in 
the Biological Opinion.

NEPA

    The U.S. Air Force (USAF) made a Finding of No Significant Impact 
(FONSI) determination on August 18, 2003, based on information 
contained within its November, 2002 Programmatic EA (PEA), that 
implementation of the subject action is not a major Federal action 
having significant effects on the environment within the meaning of 
NEPA. The USAF determined, therefore, that an environmental impact 
statement would not be prepared. NMFS noted that Eglin AFB had prepared 
a PEA for the EGTTR activity and made this PEA available upon request 
(January 23, 2006, 71 FR 3474). In accordance with NOAA Administrative 
Order 216-6 (Environmental Review Procedures for Implementing the 
National Environmental Policy Act, May 20, 1999), NMFS has reviewed the 
information contained in Eglin AFB's PEA and determined that Eglin 
AFB's PEA accurately and completely describes the proposed action, the 
alternatives to the proposed action, and the potential impacts on 
marine mammals, endangered species, and other marine life that could be 
impacted by the preferred alternative and the other alternatives. 
Accordingly, NMFS adopted Eglin AFB's PEA under 40 CFR 1506.3 and made 
its own FONSI. The NMFS FONSI also takes into consideration updated 
data and information contained in this Federal Register document, the 
proposed IHA notice (71 FR 3474, January 23, 2006) and previous notices 
(70 FR 48675, August 19, 2005). Therefore, it is not necessary for NMFS 
to issue a new EA, supplemental EA or an environmental impact statement 
for the issuance of an IHA to Eglin AFB for this activity. A copy of 
Eglin's PEA and the NMFS FONSI for this activity is available upon 
request (see ADDRESSES).

Determinations

    NMFS has determined that the A-S gunnery exercises that are 
conducted by Eglin AFB in the EGTTR in the northern GOM, are unlikely 
to result in the mortality or serious injury of marine mammals (see 
Table 11) and, would result in, at worst, a temporary elevation in 
hearing sensitivity (known as TTS). Eglin AFB estimates, and NMFS 
concurs that up to 271 marine mammals may incur this form of Level B 
harassment annually. Also, these gunnery exercises have the potential 
to result in a temporary modification in behavior by marine mammals. 
Eglin AFB estimates that up 25 marine mammals may experience a 
behavioral response to these exercises during the time-frame of an IHA. 
NMFS believes that this number may be slightly higher because estimates 
of Level B harassment by peak pressure cannot be made at this time. 
While behavioral modifications may be made by these species as a result 
of these A-S gunnery activities, any behavioral change is expected to 
result in no more than a negligible impact on the affected species. In 
addition, the potential for temporary hearing impairment is very low 
and will be mitigated to the lowest level practicable through the 
incorporation of the mitigation measures mentioned in this document. 
Finally, this activity by Eglin AFB would not have an unmitigable 
adverse impact on the availability of stocks for subsistence uses 
because there are no known subsistence uses of marine mammals in the 
Gulf of Mexico.

Authorization

    NMFS has issued an IHA to Eglin AFB for conducting A-S gunnery 
exercises within the EGTTR in the northern GOM for a 1-year period, 
provided the mitigation, monitoring, and reporting requirements are 
undertaken.

    Dated: May 3, 2006.
Donna Wieting,
Deputy Director, Office of Protected Resources, National Marine 
Fisheries Service.
[FR Doc. 06-4436 Filed 5-11-06; 8:45 am]
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