[Federal Register Volume 69, Number 188 (Wednesday, September 29, 2004)]
[Notices]
[Pages 58131-58152]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 04-21847]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

[I.D. 051704A]


Small Takes of Marine Mammals Incidental to Specified Activities; 
Marine Seismic Survey in the Gulf of Alaska, Northeastern Pacific Ocean

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

[[Page 58132]]


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 small numbers of marine mammals, 
by harassment, incidental to conducting oceanographic seismic surveys 
in the Gulf of Alaska (GOA) has been issued to Lamont-Doherty Earth 
Observatory (L-DEO).

DATES: Effective from August 30, 2004 through August 29, 2005.

ADDRESSES: The application and authorization 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, by telephoning the 
contact listed here and are also available at: http://www.nmfs.noaa.gov/prot_res/PR2/Small_Take/smalltake_info.htm#applications.

FOR FURTHER INFORMATION CONTACT: Kenneth Hollingshead, Office of 
Protected Resources, NMFS, (301) 713-2055, ext 128.

SUPPLEMENTARY INFORMATION:

Background

    Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 et seq.) 
direct the Secretary of Commerce to allow, upon request, the 
incidental, but not intentional, taking of marine mammals by U.S. 
citizens who engage in a specified activity (other than commercial 
fishing) within a specified geographical region if certain findings are 
made and either 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 that 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.''
    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. 
Except for certain categories of activities not pertinent here, the 
MMPA defines ``harassment'' as:
    any act of pursuit, torment, or annoyance which (i) has the 
potential to injure a marine mammal or marine mammal stock in the 
wild [Level A harassment]; or (ii) has the potential to disturb a 
marine mammal or marine mammal stock in the wild by causing 
disruption of behavioral patterns, including, but not limited to, 
migration, breathing, nursing, breeding, feeding, or sheltering 
[Level B harassment].
    Section 101(a)(5)(D) establishes a 45-day time limit for NMFS 
review of an application followed by a 30-day public notice and comment 
period on any proposed authorizations for the incidental harassment of 
marine mammals. Within 45 days of the close of the comment period, NMFS 
must either issue or deny issuance of the authorization.

Summary of Request

    On April 19, 2004, NMFS received an application from L-DEO for the 
taking, by harassment, of several species of marine mammals incidental 
to conducting a seismic survey program during a four-week period within 
a general time window from late July to October 2004. The purpose of 
the seismic survey is to locate sedimentary records of environmental 
change in the GOA, including Holocene climate variability, 
anthropogenic warming and glacier melting of the past century, and 
dynamics of erosion and deposition associated with glaciation. This 
research has important implications for understanding long-term 
variability of North Pacific ecosystems, with relevance towards 
managing fisheries, marine mammals and other species. Geophysical site 
survey and safety information will be used to optimally locate coring 
sites and to understand regional sedimentation patterns. The marine 
paleoclimatic record in this region has received relatively little 
study because very few suitable sediment cores have been taken. 
Nevertheless, enough basic knowledge of fjord sedimentation processes 
exists to support a strategy of targeting deep-silled basins of fjords 
with adequate connections to the open ocean, as well as shelf and slope 
sediments in the open ocean. Fjord basins likely contain a rich array 
of biogenic and sedimentologic evidence for regional climate change. 
Regions of turbidite sedimentation (i.e., coarse sediments transported 
down-slope in turbidity currents) will be documented using shipboard 
geophysical sensing and sedimentological proxies in recovered sediments 
and will be avoided during coring. However, if some isolated turbidites 
are present, this may present an opportunity to examine seismically 
triggered events that provide useful synchronous stratigraphic markers.

Description of the Activity

    The proposed seismic survey will involve one vessel, the R/V 
Maurice Ewing (Ewing). The Ewing will deploy a pair of low-energy 
Generator-Injector (GI) airguns as an energy source (each with a 
discharge volume of 105 in\3\). The energy to the airguns will be 
compressed air supplied by compressors on board the source vessel. 
Seismic pulses will be emitted at intervals of 6-10 seconds. This 
spacing corresponds to a shot interval of approximately 16-26 m (52-85 
ft). The Ewing will also tow a hydrophone streamer that is up to 1500 m 
(4922 ft) long. As the airguns are operated along the survey lines, the 
hydrophone receiving system will receive and record the returning 
acoustic signals. In constrained fjord settings, only part of the 
streamer may be deployed, or a shorter streamer may be used, to 
increase the maneuverability of the ship.
    The program will consist of approximately 1779 km (960 nm) of 
surveys, not including transits. Water depths within the seismic survey 
area are approximately 30 3000 m (98 9843 ft). There will be additional 
operations associated with airgun testing, start-up, line changes, and 
repeat coverage of any areas where initial data quality is sub-
standard.
    The GOA research will consist of four different stages of seismic 
surveys interspersed with coring operations in 4 general areas. The 4 
different stages are outlined here in the order that they are currently 
planned to take place. Transit time between areas and between lines is 
not included in the estimates of survey time below, because the seismic 
source will not be operating during transits.
    Stage 1-Prince of Wales Island. During this stage, 4 short seismic 
surveys will be completed in conjunction with 4 coring sites that will 
be sampled. Each of the 4 surveys, including seismic lines and coring, 
will take 9-14 hr and cover 17.7- 45.3 nm (32.9-83.8 km), for a total 
of 229 km (124 nm). All lines will be conducted in water depths less 
than 100 m (328 ft). A total of 13 lines will be shot around the 4 
coring stations. Stage 1 will take approximately 50 hr of survey time 
over approximately 3 days to complete.

[[Page 58133]]

    Stage 2-Baranof Island. During this stage, five short seismic 
surveys will be completed in conjunction with 6 coring sites that will 
be sampled. Each of the 5 surveys, including seismic lines and coring, 
will take approximately 6-17 hr and cover 4.1-54.5 nm (7.6-101.0 km), 
for a total of 109 km (59 nm) of which 25 km (13.5 nm) will be 
conducted in waters less than 100 m (328 ft) deep and 84 km (45 nm) 
will be in waters from 100 to 1000 m (328-3281 ft) deep. Stage 2 will 
take approximately 45 hr of survey time over approximately 4.5 days to 
complete.
    Stage 3-Juneau (Southeast Alaska Inland Waters). During Stage 3, 3 
short seismic surveys will be completed in conjunction with four coring 
sites that will be sampled. Each survey, including seismic lines and 
coring, will take approximately 8-21 hr and will cover 15.1-104.1 nm 
(27.7-192.9 km), for a total of 249 km (134 nm) conducted in water 100 
m (328 ft) to 1000 m (3281 ft) deep. Stage 3 will take approximately 38 
hr of survey time over 2.5 days to complete.
    Stage 4-Glacier Bay, Yakutat Bay, Icy Bay, Prince William Sound, 
and GOA During Stage 4, 14 seismic surveys will be conducted in 
conjunction with 16 coring sites that will be sampled. Surveys during 
Stage 4, including seismic lines and coring, will range in length from 
5.3 - 111.2 nm (9.8-205.9 km), for a total of 1192 km (644 nm) of which 
382 km (206 nm) will be conducted in waters less than 100 m (328 ft) 
deep, 453 km (245 nm) will be in waters from 100 to 1000 m (328 -3281 
ft) deep and 357 km (187 nm) will be in waters deeper than 1000 m (3281 
ft). Stage 4 will take approximately 72 hrs of survey time over 
approximately 13 days to complete.
    In the event that one or more of the planned sites are unavailable 
due to poor weather conditions, ice conditions, unsuitable geology 
(shallow sediments), or other reasons, contingency sites (alternative 
seismic survey and coring locations) will be substituted. Alternative 
research sites (see Fig. 6 in the L-DEO application) will only be 
undertaken by L-DEO as replacements for the planned sites, and their 
use will not substantially change the total length or duration of the 
proposed seismic surveys. Seismic survey lines have not been selected 
or plotted by L-DEO for some contingency core sites. However, L-DEO 
anticipates that each contingency core site would require approximately 
40 km (22 nm) of seismic surveying to locate optimal coring locations. 
It is highly unlikely that all contingency sites will be used. To the 
extent that contingency sites are used, a similar number of ``primary'' 
sites will be dropped from the project.

General-Injector Airguns

    Two GI-airguns will be used from the Ewing during the proposed 
program. These 2 GI-airguns have a zero to peak (peak) source output of 
237 dB re 1 microPascal-m (7.2 bar-m) and a peak-to-peak (pk-pk) level 
of 243 dB (14.0 bar-m). However, these downward-directed source levels 
do not represent actual sound levels that can be measured at any 
location in the water. Rather, they represent the level that would be 
found 1 m (3.3 ft) from a hypothetical point source emitting the same 
total amount of sound as is emitted by the combined airguns in the 
array. The actual received level at any location in the water near the 
airguns will not exceed the source level of the strongest individual 
source. In this case, that will be about 231 dB re 1 microPa-m peak, or 
237 dB re 1 microPa-m pk-pk. Actual levels experienced by any organism 
more than 1 m (3.3 ft) from either GI gun will be significantly lower.
    Further, the root mean square (rms) received levels that are used 
by biologists as impact criteria for marine mammals (see Richardson et 
al., 1995) are not directly comparable to these peak or pk-pk values 
that are normally used by acousticians to characterize source levels of 
airgun arrays. The measurement units used to describe airgun sources, 
peak or pk-pk decibels, are always higher than the rms decibels 
referred to in biological literature. For example, a measured received 
level of 160 decibels rms in the far field would typically correspond 
to a peak measurement of about 170 to 172 dB, and to a pk-pk 
measurement of about 176 to 178 decibels, as measured for the same 
pulse received at the same location (Greene, 1997; McCauley et al. 
1998, 2000). The precise difference between rms and peak or pk-pk 
values depends on the frequency, content, and duration of the pulse, 
among other factors. However, the rms level is always lower than the 
peak or pk-pk level for an airgun-type source.
    The depth at which the sources are towed has a major impact on the 
maximum near-field output, because the energy output is constrained by 
ambient pressure. The normal tow depth of the sources to be used in 
this project is 3 m (9.8 ft), where the ambient pressure is 3 decibars. 
This also limits output, as the 3 decibars of confining pressure cannot 
fully constrain the source output, with the result that there is loss 
of energy at the sea surface. Additional discussion of the 
characteristics of airgun pulses was provided in the notice of proposed 
authorization to L-DEO for this activity (see 69 FR 34996, June 23, 
2004) and is not repeated here. Reviewers are encouraged to read this 
earlier document for additional information.
    For the 2 GI-airguns, the sound pressure field has been modeled by 
L-DEO in relation to distance and direction from the airguns, and in 
relation to depth. Table 1 shows the maximum distances from the airguns 
where sound levels of 190-, 180-, 170- and 160-dB re 1 microPa (rms) 
are predicted to be received. Empirical data concerning the 180, 170 
and 160 dB distances have been acquired based on measurements during an 
acoustic verification study conducted by L-DEO in the northern Gulf of 
Mexico from 27 May to 3 June 2003 (Tolstoy et al., 2004). Although the 
results are limited, the data showed that radii around the airguns 
where the received level would be 180 dB re 1 microPa (rms), NMFS' 
current injury threshold safety criterion applicable to cetaceans 
(NMFS, 2000), varies with water depth. Similar depth-related variation 
is likely in both the 190-dB distances applicable to pinnipeds and the 
160-dB distance where NMFS' criteria consider Level B (behavioral 
harassment) to occur. The proposed L-DEO study area will occur in water 
approximately 30 3000 m (98 9843 ft).
    The empirical data indicate that, for deep water (>1000 m (3281 
ft)), the L-DEO model tends to overestimate the received sound levels 
at a given distance (Tolstoy et al., 2004). However, to be 
precautionary pending acquisition of additional empirical data, safety 
radii during airgun operations in deep water will be the values 
predicted by L DEO's model (see Table 1). The 180- and 190-dB radii 
were not measured for the 2 GI-airguns operating in shallow water (<100 
m (328 ft)). However, the measured 180 dB radius for the 6-airgun array 
operating in shallow water was 6.8x that predicted by L-DEO's model for 
operation of the 6-airgun array in deep water. This conservative 
correction factor is, therefore, applied to the model estimates to 
predict the radii for the 2 GI guns in shallow water. Empirical 
measurements were not conducted for intermediate depths (100-1000 m 
(328-3281 ft)). On the expectation that results will be intermediate 
between those from shallow and deep water, a 1.5x correction factor is 
applied to the estimates provided by the model for deep water 
situations. This is the same factor that was applied to the model 
estimates during L-DEO cruises in 2003.

[[Page 58134]]



Table 1. Estimated distances to which sound levels [gteqt]190, 180, 170 and 160 dB re 1 [micro]Pa (rms) might be
received from two 105 in\3\ GI guns that will be used during the seismic survey in the GOA during 2004. Distance
 estimates are given for operations in deep, intermediate, and shallow water. The 180- and 190-dB distances are
                                 the safety radii to be used during the survey.
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                                                      Estimated Distances at Received Levels (m)
             Water depth             ---------------------------------------------------------------------------
                                            190 dB             180 dB             170 dB             160 dB
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>1000 m.............................                 17                 54                175                510
100-1000 m..........................                 26                 81                263                765
<100 m..............................                250                400                750               1500
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Bathymetric Sonar, Sub-bottom Profiler, and Pinger

    In addition to the 2 GI-airguns, a multibeam bathymetric sonar and 
a low-energy 3.5-kHz sub-bottom profiler will be used during the 
seismic profiling and continuously when underway. While on station for 
coring, a 12-kHz pinger will be used to monitor the depth of coring 
devices relative to the sea floor.
    Bathymetric Sonar-Atlas Hydrosweep- The 15.5-kHz Atlas Hydrosweep 
sonar is mounted on the hull of the Ewing, and operates in three modes, 
depending on the water depth. There is one shallow-water mode and two 
deep-water modes: an Omni mode (similar to the shallow-water mode but 
with a source output of 220 dB (rms)) and a Rotational Directional 
Transmission (RDT) mode. The RDT mode is normally used during deep-
water operation and has a 237-dB rms source output. In the RDT mode, 
each ``ping'' consists of five successive transmissions, each 
ensonifying a beam that extends less than 3 degrees fore-aft and 
approximately 30 degrees in the cross-track direction. The five 
successive transmissions (segments) sweep from port to starboard with 
minor overlap, spanning an overall cross-track angular extent of about 
140 degrees, with small (much less than 1 millisec) gaps between the 
pulses for successive 30-degree segments. The total duration of the 
``ping'' including all five successive segments, varies with water 
depth, but is 1 millisec in water depths less than 500 m (1640.5 ft) 
and 10 millisec in the deepest water. For each segment, ping duration 
is \1/5\ of these values or \2/5\ for a receiver in the overlap area 
ensonified by two beam segments. The ``ping'' interval during RDT 
operations depends on water depth and varies from once per second in 
less than 500 m (1640.5 ft) water depth to once per 15 seconds in the 
deepest water. During the proposed project, the Atlas Hydrosweep is 
planned to be used in waters greater than 800 m (2624.7 ft), but 
whenever water depths are less than 400 m (1312 ft) the source output 
is 210 dB re 1 microPa-m (rms) and a single 1-ms pulse or ``ping'' per 
second is transmitted.
    Bathymetric Sonar-EM1002 Portable Sonar - The EM1002 is a compact 
high-resolution multibeam echo sounder that operates at a frequency of 
92 to 98 kHz in water depths from 10 to 800 m (33 2625 ft). The EM1002 
will be used instead of the Atlas Hydrosweep in waters less than 800 m 
(2625 ft) deep. The EM1002 will be pole mounted on the Ewing, either 
over the side of the vessel or through a well inside the ship. The 
system operates with one of three different pulselengths: 0.2, 0.7 and 
2 ms. Pulselength increases with increased water depth. Overall angular 
coverage of the transmitted beam is 3 degrees along the fore-aft axis 
and 150 degrees (7.4 times the water depth) along the cross-track axis 
when operating in the shallowest mode. Maximum ping rate is 10/sec (in 
shallow water) with the ping rate decreasing with increasing water 
depth. Maximum output using long pulses in 800 m (2624.7 ft) water 
depth is 226 dB re 1 microPa, although operations in shallower depths, 
including most of the work in these surveys, will use significantly 
lower output levels.
    Sub-bottom Profilers - The sub-bottom profiler is normally operated 
to provide information about the sedimentary features and the bottom 
topography that is simultaneously being mapped by the Hydrosweep. The 
energy from the EDO Corporation's (EDO) sub-bottom profiler is directed 
downward by a 3.5-kHz transducer mounted in the hull of the Ewing. The 
output varies with water depth from 50 watts (W) in shallow water to 
800 W in deep water. Pulse interval is 1 second (s) but a common mode 
of operation is to broadcast five pulses at 1-s intervals followed by a 
5-s pause. The beamwidth is approximately 30[deg] and is directed 
downward. Maximum source output level is 204 dB re 1 microPa (rms) (800 
W) and a nominal source output is 200 dB re 1 microPa (500 W). Pulse 
duration will be 4, 2, or 1 ms, and the bandwith of pulses will be 1.0 
kHz, 0.5 kHz, or 0.25 kHz, respectively.
    An ODEC Bathy 2000P ``chirp'' sonar may be used instead of the EDO 
sub-bottom profiler. This sonar transmits a 50-ms pulse during which 
the frequency is swept from 4 to 7 kHz. The transmission rate is 
variable from 1 to 10 seconds, and the maximum output power is 2 kW. 
This sonar uses a transducer array very similar to that used by the 3.5 
kHz sub-bottom profiler.
    Although the sound levels have not been measured directly for the 
sub-bottom profilers used by the Ewing, Burgess and Lawson (2000) 
measured sounds propagating more or less horizontally from a sub-bottom 
profiler similar to the EDO unit with similar source output (i.e., 205 
dB re 1 microPa m). For that profiler, the 160 and 180 dB re 1 microPa 
(rms) radii in the horizontal direction were estimated to be, 
respectively, near 20 m (66 ft) and 8 m (26 ft) from the source, as 
measured in 13 m (43 ft) water depth. The corresponding distances for 
an animal in the beam below the transducer would be greater, on the 
order of 180 m (591 ft) and 18 m (59 ft) respectively, assuming 
spherical spreading. Thus the received level for the EDO sub-bottom 
profiler would be expected to decrease to 160 and 180 dB about 160 m 
(525 ft) and 16 m (52 ft) below the transducer, respectively, assuming 
spherical spreading. Corresponding distances in the horizontal plane 
would be lower, given the directionality of this source (300 beamwidth) 
and the measurements of Burgess and Lawson (2000).
    12 kHz Pinger - A 12-kHz pinger will be used only during coring 
operations, to monitor the depth of the coring apparatus relative to 
the sea floor. The pinger is a battery-powered acoustic beacon that is 
attached to a wire just above the corehead. The pinger produces an 
omnidirectional 12 kHz signal with a source output of 193 dB re 1 
microPa-m. The pinger produces a 2-ms pulse every second.

[[Page 58135]]

Comments and Responses

    A notice of receipt and request for 30-day public comment on the 
application and proposed authorization was published on June 23, 2004 
(69 FR 34996). During the 30-day public comment period, comments were 
received from the Center for Biological Diversity (CBD).

Marine Mammal Concerns

    Comment 1: The CBD believes NMFS has not demonstrated that the LDEO 
project will take only small numbers of marine mammals.
    Response: NMFS believes that the small numbers requirement has been 
satisfied. The U.S. District Court for the Northern District of 
California held in NRDC v. Evans that NMFS' regulatory definition of 
``small numbers'' improperly conflates it with the ``negligible 
impact'' definition. Even if that is the case, in the proposed IHA 
notice and in this document, NMFS has made a separate determination 
that the takes of the affected marine mammal species will be small. The 
species most likely to be harassed during the seismic survey is the 
Dall's porpoise, with a ``best estimate'' of 3354 animals being exposed 
to sound levels of 160 dB or greater. Although it may be argued that 
the absolute number of Dall's porpoise behavioral harassment numbers 
may not be small, it is relatively small, representing less than 1 
percent of the regional population of that species. Moreover, this does 
not mean that 3354 Dall's porpoises will be taken by Level B 
harassment. Dall's porpoise have their best hearing at high 
frequencies, not the low frequencies used by seismic and may not even 
hear seismic sounds. If in fact, some Dall's porpoise cannot hear the 
low-frequency seismic sounds, then no taking of this species will 
occur. Finally, we note that during this project, only the humpback 
whale stock exceeds 1 percent of its stock being potentially subject to 
Level B harassment with a best estimate of about 67 animals being 
exposed to low-frequency noise.
    Comment 2: The CBD believes that the proposed authorization and L-
DEO application neglect to provide sufficient analysis of the 
additional impacts to marine mammals resulting from the project's 
nearshore and inland location.
    Response: NMFS believes that the L-DEO application and the National 
Science Foundation's (NSF) Environmental Assessment (EA) provide the 
necessary information and analyses needed for NMFS to make a 
determination on whether or not the proposed incidental harassment 
takings will be small and have no more than a negligible impact on 
marine mammals. These documents provide detailed analyses on the 
impacts on the affected marine mammal species including when they are 
in the nearshore environment and calculate conservative estimates for 
sound source ranges due to sound attenuation rates for the seismic 
source in shallow water.
    The LDEO application describes how seismic sounds can be received 
in the ocean. This is important for estimating impacts. Seismic sound 
received at any given point will arrive via a direct path, indirect 
paths that include reflection form the sea surface and bottom, and 
often indirect paths including segments through the bottom sediments. 
Sound propagating via indirect paths travel longer distances and often 
arrive later than sounds arriving via a direct path. These variations 
in travel time have the effect of lengthening the duration of the 
received pulse, reducing the potential for impacting marine mammals.
    As mentioned in the L-DEO application, received levels of low-
frequency underwater sounds diminish close to the surface because of 
pressure-release and interference phenomena that occur at and near the 
surface (Urick, 1983; Richardson et al., 1995). Paired measurements of 
received airgun sounds at depths of 3 m (9.8 ft) vs 9 m (29.5 ft) or 18 
m (59 ft) have shown that received levels are typically several 
decibels lower at 3 m (Greene and Richardson, 1988). This results in 
lowered SPLs at the surface than at depth, essentially providing 
protection for surface-inhabiting marine species. However, when 
establishing 180-dB and 190-dB safety zones, NMFS and L-DEO calculated 
safety zones by using the greatest 180/190 dB SPL distance at depth 
from the source. This results in higher (more conservative) estimates 
of take since most marine mammals, such as the dolphins, are expected 
to be in the near-surface zone of the ocean most of the time.
    During a 2003 study in the northern Gulf of Mexico, LDEO obtained 
measurements of received sound levels as a function of distance from 
LDEO's airgun arrays. The calibration measurements indicate that 
received levels in shallow water (30 m) diminish less rapidly, as noted 
previously in this document. This is what would be expected in inland 
waters and has been taken into consideration when establishing 
conservative safety zones to protect marine mammals from injury. 
Further discussion on this subject will be presented in response to 
comment (RTC) 9 later in this document.
    Comment 3: The CBD believes that NMFS' analyses of small numbers 
and negligible impact are flawed, because NMFS uses ``North Pacific 
Ocean'' to define the geographical limits of the ``regional'' 
populations that form the basis of its analyses instead of providing an 
analysis of impacts on stocks or more localized populations that 
overlap with the project area. The CBD believes that the appropriate 
geographic scale should be populations and stocks inhabiting the survey 
area and not the entire North Pacific.
    Response: NMFS agrees that impacts should be assessed on the 
population or stock unit whenever possible. L-DEO's application (see 
especially Table 3) provides information on stock abundance in Alaska 
(when available) and larger water bodies (such as the North Pacific 
Ocean). The data source for each stock estimate is provided. NMFS 
believes that these data are the best scientific information available 
for estimating impacts on marine mammal species and stocks. However, 
information on marine mammal stock abundance may not always be 
satisfactory. When information is lacking to define a particular 
population or stock of marine mammals then impacts are assessed with 
respect to the species as a whole (54 FR 40338, September 29, 1989).
    Comment 4: The CBD believes that the appropriate geographical scale 
is particularly critical for species, such as the Northern Resident, 
Gulf of Alaska Transient, and the ``depleted'' AT1 stocks of the killer 
whale. NMFS does not even mention the impacts of the proposed 
authorization on these stocks of killer whales in the proposed 
authorization, rendering the analysis wholly useless. The take of even 
one killer whale from these stocks will have more than a negligible 
impact on the stock and the species.
    Response: Information on the killer whale stocks was provided on 
pages 20 and 21 of the L-DEO application and in NMFS' proposed 
authorization (see 69 FR 34996 (June 23, 2004) especially Table 2). It 
was not separated out for additional discussion in NMFS' notice since, 
as noted later, the killer whale is less likely to be impacted than 
most other species and, therefore, did not warrant additional analysis. 
For clarification in calculating killer whale density, L-DEO used the 
survey data of Waite (2003). This estimate is based on eight killer 
whale sightings during 2242 km (1210.6 nm) of survey effort. In 
calculating density an allowance is given for prorating some 
unidentified animals to killer whales based on the ratio of identified 
animals of the same grouping, which includes small whales or any less 
precise grouping which

[[Page 58136]]

includes small whales, such as unidentified whale. The final density in 
the table of 0.0136/sq km has been adjusted upward from the raw density 
of 0.0125 based on only the 8 killer whale sightings.
    Referencing Agliss and Lodge (2002), L-DEO notes that the best 
scientific information currently available indicates that the minimum 
population size of killer whales in Alaskan waters is 1069, which 
includes minimum population (Pmin) estimates of 723 Eastern 
North Pacific (ENP) Resident and 346 ENP Transient killer whales. A 
Pmin estimate is considered to be conservative. On June 3, 
2004 (69 FR 31321), NMFS published a final rule designating the AT1 
killer whale group as a depleted stock under the MMPA. This group 
currently has 9 or fewer whales and was part of the ENP Transient stock 
prior to this designation.
    Since there is insufficient information to indicate which of these 
stocks, if any, might be within the relatively small impact area at the 
same time the Ewing is conducting seismic, the proper method is either 
to combine these population stock estimates or divide the estimated 
incidents of harassment between the current three stocks. Since this 
species is unlikely to be in the vicinity of the Ewing at the time 
seismic is operating (L-DEO, 2004), and is highly visible to observers, 
no killer whales will be injured or killed (i.e., no removals from the 
species or stock) as a result of the Ewing's seismic operations. 
Therefore, the only potential taking might be by Level B harassment. As 
indicated in Table 2 in this document, L-DEO estimates that 
approximately 42 killer whales might be within the 160-dB (rms) 
isopleth and, therefore, presumed to be harassed. This is 0.2 percent 
of the regional killer whale population. If subdivided according to 
stock size, NMFS estimates that about 28 ENP Resident, 13 ENP Transient 
and significantly less than 1 AT1 animal would be within the 160 dB 
isopleth. Moreover, since the killer whale's optimum hearing range is 
not in the low frequency used by seismic sources, this number should 
not be interpreted as the number being ``taken'' by Level B harassment, 
only the number that might be exposed to that noise. Therefore, NMFS 
does not believe that the effect of any taking will be more than 
negligible.
    Comment 5: The CBD states, furthermore, that while some 16 other 
pods inhabit or visit SE Alaskan waters and Prince William Sound, they 
are not formally recognized as ``stocks.'' Scientifically many of these 
pods warrant recognition as such and must be analyzed under both the 
MMPA and the National Environmental Policy Act (NEPA).
    Response: L-DEO has used the best scientific information available 
regarding killer whale stock structure (and the stock structure for 
other species). For killer whales and other species, NMFS and L-DEO 
used stock structure information provided in Angliss and Lodge (2002) 
and other documents referenced in the L-DEO application and NSF EA. 
Since the CBD has not provided additional information that indicates 
this information is invalid, NMFS must base its determinations on this 
information.
    Comment 6: The CBD states that the proposed authorization notice 
neglects to explain how the population estimates provided in L-DEO's 
application and NSF's EA correspond to populations or stocks or how L-
DEO/NMFS use this information for take estimates. For example, the 
application and EA estimate the SE Alaskan population of humpback 
whales to be 404 individuals. However, the proposed authorization 
states that 67 individuals will be exposed to sound levels greater than 
160 dB, which it concludes represents only 1.1 percent of the 
``regional population.'' However, 67 individuals represents 17 percent 
of the SE Alaskan population, which is the proper geographic scope of 
the take analysis.
    Response: L-DEO clearly states that it uses the ``regional 
population estimates'' that are given in Table 3 of the EA and 
corresponding table of the IHA application, not the ``local population 
estimates'' which CBD suggests are ``the appropriate numbers to use''. 
In some cases, L-DEO/NSF can sum the estimates for specific stocks but 
in most cases there is no specific stock information for the survey 
area. In situations where there is specific information for the survey 
area there is rarely information for all adjacent survey areas. 
Including this point, there are a several additional points that apply 
to most L-DEO projects.
    1. The stocks (local populations) considered by NMFS for management 
purposes (involving lethal takes or removals from the population by 
commercial fishing or other activities) often do not include all of the 
animals that inhabit that area over the year, or even during the same 
season or year. Local stock estimates frequently include only the 
animals that are present at the time of a particular marine mammal 
survey and thus substantially underestimate the number that use the 
area over a longer time period. For example, the Oregon stock of 
Pacific white-sided dolphins (see 69 FR 31792, June 7, 2004) includes 
animals that can be found in California at one time of year and perhaps 
British Columbia or SE Alaska at another time, and the number of 
different animals that are found in Oregon waters over the year is many 
times the number that occur there at any one time. Thus, in most cases, 
estimates of stock size for local populations are minimum estimates 
with no realistic estimate of the upper bound of the population size.
    2. For many species there is a great deal of year-to-year movement 
by marine mammals to take advantage of resources. Animals that normally 
inhabit one area are not restricted to that area. When, for example, 
food is scarce in an area animals will temporarily move into other 
areas to take advantage of abundant food in those areas. Definitions of 
local stocks do not consider this flexibility.
    3. Telemetry and photo-id studies reveal that there is interchange 
between what are considered to be discrete stocks. There are many 
examples of between-stock movements of humpback and southern right 
whales. Most recently large numbers of right whales seen off of 
southern Brazil appear to be immigrants from Peninsula Vades, Argentina 
(Groch et al., 2004), which until recently was thought to be a separate 
stock. Local stocks are thus overly conservative and a low estimate of 
the populations that use an area. While these estimates may be 
warranted when considering limits on lethal takes, in order to ensure 
that populations continue to grow, they are overly conservative when 
considering effects of behavioral disturbance, which are not expected 
to have any demographic consequences to the populations.
    Therefore, in SE Alaska, NMFS and L-DEO believe there are no good 
``local'' population estimates for any cetacean species in SE Alaska, 
perhaps with the exception of harbor porpoises and Pacific white-sided 
dolphins. The surveys that provided the density estimates (Waite, 2003) 
were conducted in the GOA (which is only partially relevant to SE 
Alaska) and only a few surveys of harbor porpoises and Pacific white-
sided dolphins have actually been conduced in SE Alaska.
    In regard to the humpback whale, although there are estimated to be 
greater than 6000 humpback whales in the North Pacific, only about 1200 
are accounted for by estimates of numbers in the feeding areas because 
all surveys of summering areas are incomplete. Thus Straley et al.'s 
(1995) estimate of the 404 humpbacks using SE Alaska waters is some 
unknown fraction of the total number there. Therefore, NMFS

[[Page 58137]]

and L-DEO believe that, until more complete data are obtained, the 
North Pacific humpback whale estimate is the best data available for 
use here.
    Comment 7: The CBD states that surveys should be conducted prior to 
authorizing the IHA for those species for which the Alaskan marine 
mammal populations are not known, asserting that any analysis of small 
numbers and negligible impact cannot be conducted independently of this 
more detailed information.
    Response: NMFS disagrees. As noted previously, when information is 
unavailable on a local population size, NMFS uses either stock or 
species information on abundance. Since NMFS uses the best information 
that is available, estimating impacts on marine mammals in this manner 
is appropriate. Therefore, additional surveys are unnecessary.
    Comment 8: CBD states that there is insufficient disclosure of the 
compounded impact of the 2 GI-airgun array's seismic output along with 
the other data acquisition systems, the bathymetric sonar, sub-bottom 
profiler and pinger. Despite the fact that the sonar and pinger will be 
operating continuously during the voyage, NMFS assumes there will be no 
additional take from the sonar, profiler, and pinger individually or 
from all three sources collectively. Therefore, NMFS must address 
instances when all sources may not be operating simultaneously and also 
provide a substantiated explanation why it assumes there is no enhanced 
impact of multiple acoustic sources operating together.
    Response: This information is provided in detail in the L-DEO 
application and NSF EA. The multibeam sonars and sub-bottom profilers 
have anticipated radii of influence significantly less than that for 
the airgun array. NMFS has stated previously that marine mammals close 
enough to be affected by the multibeam sonar or sub-bottom profiler 
would already be affected by the airguns when they are both working. 
Since NMFS considers all marine mammals to be affected equally by 
underwater sound and does not determine which species are low-frequency 
hearing specialists and therefore more affected by seismic (a low-
frequency source) and which species are mid- or high-frequency 
specialists and therefore more likely to be affected by the sonars, 
NMFS does not consider it is necessary to conduct an analysis on the 
enhancement of effects for animals that might be affected by these 
sonars. In other words, the acoustic source with the largest zone of 
influence is used to determine incidental take levels.
    Also, estimates of incidental take by harassment for times when the 
multibeam sonar and/or sub-bottom profiler are operated without airguns 
are not necessary because the 160-dB and 180-dB isopleths of the sub-
bottom profiler and multibeam are either too small or the acoustic 
beams are very narrow, making the duration of the exposure and the 
potential for taking marine mammals by harassment small to non-
existent. As provided in the L-DEO application, the 160-dB and 180-dB 
radii in the horizontal direction for the sub-bottom profiler are 
estimated to be near 20 m (66 ft) and 8 m (26 ft), respectively. In the 
vertical direction, the 160-dB and 180-dB radii are 160 m (525 ft) and 
16 m (52 ft) directly below the hull-mounted transducer. With the 
Ewing's beam at 14.1 m (46.25 ft) little noise is, therefore, likely to 
exist at the water surface beyond the immediate vicinity of the Ewing 
from this hull-mounted sonar. As a result, it is unlikely that marine 
mammals would be affected by sub-bottom profiler signals whether 
operating alone or in conjunction with other acoustic devices since the 
animals would need to be swimming immediately adjacent to the vessel or 
directly under the vessel. This is unlikely to occur during the Ewing 
cruise since the vessel is likely to be in transit mode when not coring 
or towing seismic, and will therefore be traveling at about 10-11 knots 
(18.5-20.4 km/hr) at the time.
    For the Hydrosweep there is minimal horizontal propagation, as 
these signals project downward and obliquely to the side at angles up 
to approximately 70 degrees from the vertical, but not horizontally. 
For the deep-water mode, under the Ewing these 160- and 180-dB zones 
are estimated to extend to 3200 m (10500 ft) and 610 m (2000 ft), 
respectively. However, the beam width of the Hydrosweep signal is only 
2.67 degrees fore and aft of the moving vessel, meaning that a marine 
mammal diving (not on the surface) could receive at most 1 to 2 signals 
from the Hydrosweep. Also, because NMFS treats behavioral harassment or 
injury from pulsed sound as a function of total energy received, the 
actual harassment or injury threshold for Hydrosweep signals 
(approximately 10 millisec in duration) would be at a much higher dB 
level than that for longer duration pulses such as seismic or military 
sonar signals. As a result, NMFS believes that marine mammals are 
unlikely to be harassed or injured from the multibeam sonar or the 
Hydrosweep sonar due to the short duration and only 1 to 2 pulses 
received. In addition, at 95-kHz, the sounds from the EM1002 
bathymetric sonar would not even be audible to pinnipeds and baleen 
whales.
    Finally, the 12-kHz pinger has a weak signal compared to other 
acoustic sources (at 193 dB its signal is weaker than even most off-
the-shelf commercial (e.g., fish-finder) sonars used by recreational 
and commercial boaters) and will be used only when on-station for 
coring to monitor the depth of the apparatus relative to the sea floor. 
Therefore, the 12-kHz pinger is unlikely to be used in conjunction with 
other acoustic devices. Since the vessel is stationary at the time of 
coring, a marine mammal would need to approach the Ewing on its own and 
essentially swim under the vessel to be exposed to sound levels greater 
than 160 dB. As a result, NMFS does not believe that incidental takings 
will occur from this acoustic device.

Mitigation Concerns

    Comment 9: The CBD believes that NMFS' discussion of measures to 
ensure the least practicable impact is lacking. For example, NMFS 
provides no analysis of why larger safety radii were not practicable or 
why additional correction factors were not provided for nearshore and 
inland water locations of the seismic activities and the possible 
enhanced impacts these locations could produce.
    Response: Safety zones were established and are monitored closely 
to ensure, to the greatest extent practicable, that no marine mammals 
would be injured by the proposed activity. While extending safety zones 
to reduce Level B behavioral harassment would, in theory, result in 
reducing ``takes'' further, monitoring larger safety zones results in 
lower effort directed to the area of greatest concern, the area for 
potential injury. This lower effort might result in missed animals. For 
that reason, NMFS has determined that safety zones should be 
established and monitoring at 180 dB for cetaceans and 190 dB (rms) for 
pinnipeds.
    Additional correction factors for calculating safety zones are 
necessary based on attenuation due to water depth, not because of 
distance to shore (although in most cases the two are related). 
Underwater seismic sounds are subject to spherical spreading to a 
distance approximately 1.5 times water depth. This is essentially what 
occurred in the Gulf of Mexico seismic study (see RTC 2 in this 
document). These additional correction factors were applied for L-DEO 
seismic activities taking place in water depths less than 1000 m (3281 
ft) as described elsewhere

[[Page 58138]]

in this document. However, NMFS has some concerns regarding propagation 
in very shallow water and has determined that for water depths less 
than 100 m (328 ft), L-DEO will establish a safety zone at 170 dB as 
shown in Table 1.
    Comment 10: The CBD states that NMFS has not provided an acceptable 
justification for allowing L-DEO to abandon use of passive acoustic 
monitoring (PAM). They assert that despite any alleged limitations of 
PAM on their voyage, it still constitutes a meaningful mitigation 
measure that is necessary to ensure least practicable impacts to marine 
mammals and this must be required.
    Response: It must be noted that the 180-dB safety radius for the 2-
GI airgun array is 54 m (177 ft) in deep water, 81 m (266 ft) in 
intermediate-depth waters; the 170-dB safety zone in shallow water is 
750 m (2461 ft). Because of the relatively small safety zones in 
intermediate and deep water, locating vocalizing marine mammals to 
determine presence within the safety zone is not possible. Also, while 
detecting vocalizing marine mammals to determine presence simply alerts 
observers to their presence and does not initiate shutdown because the 
PAM cannot determine distance to the vocalizing animal, at these short 
distances and slow vessel speed, a trained marine mammal observer 
should not have difficulty locating them visually without the PAM. Of 
the 1776 km (959 nm) of seismic lines for this survey, the major 
portion (1143 km (617 nm)) will be in intermediate or deep water where 
the safety zones are small. In shallow water, where the safety zone 
will be larger, the PAM has proven inefficient due to signal 
propagation loss and reflection characteristics in shallow water. For 
these reasons, NMFS is not requiring L-DEO to use the PAM during the 
GOA research program.
    Comment 11: The CBD states that NMFS' analysis of mitigation 
measures to ensure least practicable impact is flawed because the 
notice fails to require dedicated observers at night.
    Response: Unlike most seismic surveys, the GOA work will involve 
about 29 separate surveys with each one followed by 9-14 hours of 
coring operations and transit times to the next coring/seismic station. 
These periods will allow the observers onboard the Ewing to rest and/or 
sleep. However, for this operation NMFS is also requiring use of either 
the Ewing during its return to the coring site or its small boat during 
coring (if safety concerns can be met) to look for marine mammals on 
the vessel track. This will require one observer to be available during 
the coring operation, but leave two observers time to rest. In 
addition, to the maximum extent possible, NMFS is requiring seismic 
work to be conducted during daytime when in the fjords so night-time 
seismic work will be very limited (essentially to those times when 
darkness arrives at the end of a seismic leg). Therefore, due to the 
shortness of each seismic leg, for this research cruise observers will 
be available to conduct night-time observations when working in 
offshore waters and crew members will only assist the observers.
    Comment 12: The CBD states that there is no discussion or 
consideration of additional monitoring or mitigation measures, such as 
aerial surveys during operations to search for animals that may be 
affected, as well as to search nearby remote beaches for possible 
stranded animals. Without requiring such additonal measures, or at a 
minimum discussing why they are not practical, NMFS cannot lawfully 
issue the requested authorization.
    Response: Prior to issuing an IHA, NMFS thoroughly investigates all 
measures that might be practical to reduce the incidental taking of 
marine mammals by an activity to the lowest level practicable. Some of 
these mitigation measures were summarized in RTC 11. Additional 
mitigation measures are discussed later in this document (see 
Mitigation). Mitigation measures, such as aerial overflights or support 
vessels to look for marine mammals prior to an animal entering a safety 
zone, are generally given consideration if the safety zone cannot be 
adequately monitored from the source vessel. Additional consideration 
must be given, however, to aircraft/vessel availability and access to 
nearby airfields and aircraft flight duration. There are serious safety 
issues regarding aircraft flights over water that must be considered 
prior to requiring aerial overflights. Additional consideration must be 
given to the potential for aircraft to also result in Level B 
harassment since a plane or helicopter would need to fly at low 
altitudes to be effective. Because the safety zones for this proposed 
activity are small and can be easily monitored from the Ewing, use of 
aircraft for mitigation purposes is not warranted.
    If aircraft are not necessary or feasible to monitor a safety zone, 
then one needs to see if aircraft might be needed to monitor shorelines 
(presumably for strandings related to the activity). NMFS has carefully 
weighed the suggestion of aerial monitoring of beaches and shorelines 
for standings and has determined that for this GOA survey, using the 
Ewing's small boat or the Ewing itself would be more effective in 
locating marine mammals in and near the Ewing's track than would an 
aircraft. An aircraft would be seriously constrained by altitude and a 
lack of ability to determine whether the mammal had been affected by 
seismic or was a natural stranding. That the stranding is related to 
the activity requires verification and verification can only be done in 
this area by a vessel or a land-based team. Verification is important 
because marine mammal stranding is a phenomenon that precedes the 
introduction of anthropogenic noises into the oceans and the vast 
majority of all strandings world-wide are unrelated to anthropogenic 
noise. Considering the topography, inaccessibility of the shoreline and 
the short-duration of each coring leg, a land-based team is not 
practical, leaving only the Ewing or its boat for verification. This is 
the alternative chosen by NMFS.

Endangered Species Act (ESA) Concerns

    Comment 13: The CBD states that L-DEO's proposed project may affect 
9 species listed as endangered under the ESA. As a result, consultation 
under section 7 of the ESA must occur prior to authorization of the 
project. NMFS has not yet complied with its (ESA) duties, and thus may 
not issue a small take authorization for the LDEO project.
    Response: NMFS has completed consultation under section 7 of the 
ESA for both NMFS and the U.S. Fish and Wildlife Service (FWS) species. 
The biological opinion resulting from that consultation concluded that 
this action is not likely to jeopardize the continued existence of 
listed species or result in the destruction or adverse modification of 
critical habitat.

NEPA Concerns

    Comment 14: The CBD believes that the EA is insufficient and that 
an Environmental Impact Statement(EIS) is required. The CBD states that 
NSF and NMFS have never prepared a comprehensive EIS that fully 
analyzes the environmental impacts of its seismic surveys, either 
individually or collectively, as well as provide the public with the 
critical opportunity to participate in the decision making process as 
required by NEPA for actions of this magnitude. The CBD believes that 
NMFS must prepare an EIS prior to approving this project.
    Response: NMFS disagrees. In its review of NSF's EA for this action 
and previous L-DEO actions that were analyzed under individual EAs, 
NMFS has determined that the proposed L-DEO actions are dispersed

[[Page 58139]]

geographically (Bermuda, Norway, Mid-Atlantic, Gulf of Mexico, 
Caribbean Sea, Eastern Pacific) and/or time-wise (Hess Deep, 2003 and 
Blanco Fracture, 2004). As a result, there are no cumulative effects 
because there are no removals from any marine mammal population, Level 
B harassment would only affect widely disbursed marine mammal 
populations and those affects would not impact animals at the 
population level and, therefore, would be negligible. Also, NMFS 
announced the availability of this NSF EA on June 23, 2004 (69 FR 
34996), as it does all NSF EAs.
    Comment 15: Prior to approving this project, NMFS must prepare an 
EIS. An EIS is required if ``substantial questions are raised as to 
whether a project...may cause significant degradation of some human 
environmental factor.'' (Idaho Sporting Congress v. Thomas, 137 F.3d 
1146, 1149-50 (9th Circ. 1998) citing Greenpeace Action v. Franklin, 14 
F.3d 1146, 1149-1150 (9th Cir. 1998). The CBD states that one need not 
show that significant effects will in fact occur; rather, raising 
substantial questions whether a project may have a significant 
environmental effect is sufficient. In this case, an EIS is required 
because substantial questions have been raised as to each of the 
factors found in 40 CFR 1508.27(b)), a few of which are discussed in 
greater detail (see RTCs 16-20).
    Response: NMFS believes that the NSF EA provides an in-depth 
discussion on aspects of the impacts of seismic and sonar sounds on 
marine life, particularly marine mammals and sea turtles. For example, 
it discusses and analyzes impacts on, and the relationship between, 
military sonar and marine mammal strandings, in addition to the 
potential interaction between marine mammals and seismic operations. In 
conclusion, and as shown in the RTCs that follow, NMFS has determined 
that this project, as described in the NSF EA, does not raise 
substantial issues requiring an EIS.
    Comment 16: The CBD states it cannot be disputed that there are 
``uncertain impacts or unknown risks'' associated with this project and 
other similar seismic surveys and geophysical activities undertaken by 
L-DEO and NSF and authorized by NMFS. There exist large data gaps 
regarding the impacts of acoustics on marine life. Given the many 
stranding events that have been linked to underwater acoustics, 
including the melon-headed whale stranding near Hanalei Bay, Hawaii, a 
more detailed analysis in the form of a full EIS is more than 
warranted.
    Response: While NMFS agrees that there are some unknown risks and 
uncertain impacts associated with this project for which NMFS has 
implemented precautionary mitigation measures, the major issue is in 
regard to the biological mechanism that is causing some strandings 
related to sound to occur. Also, it is recognized by many scientists 
that there are data gaps because of the difficulty of obtaining data in 
a humane manner from many of the species for which we do not have data. 
In those cases, surrogate species are used and conservative measures 
taken to ensure that injury or mortality to these animals does not 
occur. This current state of knowledge has been fully described in the 
NSF EA and no additional information or analyses would be available for 
use in an EIS. Finally, NMFS would like to clarify that the melon-
headed whale stranding near Hanalei Bay was not caused by seismic 
survey work.
    Comment 17: The CBD states there is significant controversy over 
the impacts of underwater seismic activity on the environment. For 
example, there are extremely divergent views on how substantial a 
change in behavior or activity is required before an animal should be 
deemed to be harassed or impacted, what received sound levels can be 
considered ``safe,'' what mitigation measures are effective, and, in 
general, how to proceed in the face of existing scientific uncertainty 
on these and other issues.
    Response: These issues relate more to interpretation and 
application of the MMPA than to impacts on the human environment; in 
this case, principally impacts on marine mammals. While organizations 
such as the National Research Council recommend other interpretations, 
as detailed in the L-DEO application and the NSF EA, calculations for 
Level B harassment used here are based upon conservative assumptions of 
distance from the source for impact and do not make a distinction as to 
whether the harassment is biologically significant. Since the majority 
of the marine mammal species likely to be impacted by this action are 
pinnipeds or members of the Delphinidae family, which have their best 
hearing at frequencies much greater than the predominant seismic 
frequencies, establishing a Level B harassment at 160 dB is considered 
conservative. Also, while there is currently a debate as to what 
mitigation measures are effective, it should be noted that in the L-DEO 
application, estimates of take (mortality, injury, or harassment) are 
made without consideration that mitigation is effective. There is also 
no significant controversy over whether or not to issue incidental take 
authorizations in the face of scientific uncertainty. While some 
members of the public recommend NMFS deny almost all authorizations 
under section 101(a)(5) of the MMPA, NMFS is charged to determine 
whether takings should be allowed based upon the best scientific 
information currently available. When some portion of that information 
is unavailable, NMFS proceeds in a precautionary manner ensuring that 
such takings are small, negligible and at the lowest level practicable.
    Finally, it should be understood that NMFS and other federal 
agencies have issued EAs in the past for seismic activities, such as in 
Southern California (NMFS, 1997), the Beaufort Sea (NMFS, 1998, 1999) 
and the Gulf of Mexico (Minerals Management Service, 2004). All these 
documents used similar criteria for determining impacts to marine 
mammals from seismic sources.
    Comment 18: The CBD states that L-DEO, NSF, and numerous private 
seismic vessels may have as yet unanalyzed cumulatively significant 
effects on the environment. Cumulative impacts include the impact on 
the environment which results from the incremental impact of the action 
when added to other past, present, and reasonably foreseeable future 
significant actions. While NSF identifies fishing, shipping and vessel 
noise, hunting, and marine tourism as cumulative effects on the 
environment, it only provides a general description of each activity 
and never analyzes their individual or combined impact on the marine 
environment. It also neglects to analyze the cumulative impacts to 
individuals of repeated exposures from the proposed project. The CBD 
claims that the EA turns the findings in Neighbors of Cuddy Mountain v. 
U.S. Forest Service 137 F.3d 1372, 1379 (9th Circ. 1998) on its head 
and concludes that ``[i]mpacts of the L-DEO's proposed survey in SE 
Alaska and the GOA are expected to be no more than a very minor (and 
short-term) increment when viewed in light of other human activities 
within the study area.'' NMFS must conduct its own cumulative impacts 
analysis to remedy this deficiency.
    Response: The NSF EA adequately addresses the cumulative impacts of 
a short-term, low-intensity seismic airgun survey in relation to long-
term noise and taking events, such as shipping, fishing, and marine 
tourism. These latter events are long-term activities over which 
neither NSF nor NMFS can affect by NMFS' decision on this action. 
Therefore, greater in-depth analyses of these activities are not needed 
for the decision-making process here.

[[Page 58140]]

    In regard to the CBD comment on repeated exposures, such an event 
is discussed in the NSF EA and in the L-DEO application. This 
information was summarized in Table 6 of the application and in Table 2 
in both the notice of proposed IHA and in this document. Comparing the 
number of exposures calculated versus the number of individuals that 
may be exposed indicates that few mammals would likely be taken by 
Level B harassment more than a single time. This is due to the 23-29 
different survey sites for this research, the short-time at each site 
and the unlikely chance that a single mammal would be found in more 
than a single location during the month-long survey.
    Comment 19: The CBD states that the proposed project and other 
activities in the area have the potential to impact species listed 
under the ESA, including sperm, humpback, sei, fin, blue, and North 
Pacific right whales, the Steller sea lion, and the leatherback and 
green sea turtles. Therefore, it believes and EIS is required.
    Response: Impacts on marine species listed under the ESA have been 
addressed in NMFS' Biological Opinion on the proposed action of 
conducting a marine seismic survey in the GOA under an authorization 
for the harassment of marine mammals incidental to conducting that 
activity. The finding of that biological opinion is that this action is 
not likely to jeopardize the continued existence of listed species or 
result in the destruction or adverse modification of critical habitat. 
No listed species are expected to be killed or seriously injured, all 
impacts will be short-term resulting in no more than minor behavioral 
harassment, and no critical habitat will be destroyed. The L-DEO action 
does not rise to a level of significance requiring preparation of an 
EIS.
    Comment 20: The CBD states that the project is slated for a 
geographically unique and highly productive ecosystem containing 
critically important ecological resources, including Steller sea lion 
rookeries and haul-outs, critical stocks and populations of species, as 
well as a complex system of de-glaciated fjords that complicates 
estimating the environmental impacts of acoustic research. The presence 
of these and other significance factors clearly triggers the need for 
an EIS.
    Response: As noted in the EA and in the L-DEO application, the 
proposed seismic survey will not result in any permanent impact on 
habitats used by marine mammals or to the food resources they (and 
other species) utilize. The main impact associated with the seismic 
survey activity will be temporarily elevated noise levels that affect 
marine mammals and other species as detailed in the EA. The EA also 
addresses propagation of sounds in inshore waters and accommodates the 
complex nature of fjords by incorporating conservative mitigation 
measures, such as an increased safety zone size, to ensure that marine 
mammals are not injured.
    Comment 21: The CBD states that the EA lacks the required 
environmental baseline data and adequate analysis of impacts and 
mitigation measures as discussed previously. Mere conclusions does not 
satisfy NEPA (ref: Blue Mountain Biodiversity Project v. Blackwood 161 
F.3d 1208, 1213 (9th Cir. 1998), cert denied, 527 U.S. 1003 (1999)).
    Response: NMFS disagrees. NMFS believes that the EA provides a 
level of detail not usually found in many Environmental Assessments. 
The EA provides a step-by-step analysis on how impacts were assessed, 
starting with (and citing) the best scientific information available on 
marine mammal and sea turtle distribution and abundance and using those 
data to make conservative estimates on levels of take by harassment and 
reasonable assumptions on why no marine mammals are likely to be 
injured or killed by this survey. A discussion on addressing the 
mitigation measures as alternatives to the proposed action is provided 
in the next response.
    Comment 22: The CBD states that the EA does not evaluate a 
reasonable range of alternatives. The EA does not analyze any 
alternative that incorporated more mitigation or otherwise lessened the 
impacts of the seismic operations on the marine environment. The EA 
only analyzes the Proposed Action alternative, the No Action 
alternative, and a generic Another Time alternative. NSF and L-DEO's 
unilateral decision to commit resources to a particular (ship) schedule 
cannot excuse them from full compliance with NEPA or be used to 
restrict the alternatives analysis of the EA.
    Response: NMFS has reviewed the range of alternatives addressed in 
NSF's EA and agrees that the alternatives can be expanded by providing 
additional analysis of the mitigation measures that were considered for 
use during seismic surveys (but not necessarily practicable for each 
and every survey). For reader convenience that discussion has been 
provided in this document and in NMFS' Finding of No Significant Impact 
(FONSI) determination (see NEPA later in this document).
    Comment 23: The CBD states that the EA is also grossly deficient in 
its discussion of potential impacts to fish species. While the EA 
briefly describes various fisheries in the area, it concludes without 
analysis that ``It is not expected that L-DEO's operations will have 
significant impact on commercial fisheries in the GOA.''
    Response: That is not totally correct. The EA states that ``fish 
often react to sounds, especially strong and/or intermittent sounds of 
low frequency. Sound pulses at received levels of 160 dB re 1 [micro]Pa 
(peak) may cause subtle changes in behavior. Pulses at levels of 180 dB 
(peak) may cause noticeable changes in behavior (Chapman and Hawkins, 
1969; Pearson et al., 1992; Skalski et al., 1992).'' NMFS believes that 
significant changes in behavior would mean that these fish might be 
unavailable to line and gillnet fisheries (but not necessarily trawl 
fisheries) for some period of time. The rms value for a given airgun 
pulse is typically about 10 dB lower than the peak level, so this fish 
impact zone extends to approximately the 170 dB (rms) isopleth around 
the vessel. As indicated in Table 1, the 170-dB rms isopleth radius 
will range from 175 to 750 m (574 to 2461 ft), depending upon water 
depth. It also appears that fish often habituate to repeated strong 
sounds rather rapidly, on time scales of minutes to an hour. Since L-
DEO notes in the EA that they will avoid areas of fishing activity, and 
as fishing vessels will likely avoid seismic vessels simply because of 
the potential to entangle fishing gear with seismic gear, NMFS is 
confident that the EA has provided the level of information necessary 
to determine that the Ewing survey in the GOA will not have a 
significant effect on fish or fisheries.

Description of Habitat and Marine Mammals Affected by the Activity

    A detailed description of the GOA area and its associated marine 
mammals can be found in the L-DEO application and a number of documents 
referenced in the L-DEO application, and is not repeated here. A total 
of 18 cetacean species, 3 species of pinnipeds, and the sea otter are 
known to or may occur in SE Alaska (Rice, 1998; Angliss and Lodge, 
2002). The marine mammals that occur in the proposed survey area belong 
to four taxonomic groups: odontocetes (sperm whales[ast] (Physeter 
macrocephalus), beaked whales (Cuvier's[ast] (Ziphius cavirostris), 
Baird's[ast] (Berardius bairdii), and Stejneger's (Mesoplodon 
stejnegeri)), beluga

[[Page 58141]]

(Delphinapterus leucas), Pacific white-sided dolphin[ast] 
(Lagenorhynchus obliquidens), Risso's dolphin (Grampus griseus), killer 
whale[ast] (Orcinus orca), short-finned pilot whale (Globicephala 
macrorhynchus), harbor porpoise[ast] (Phocoena phocoena), and Dall's 
porpopise[ast] (Phocoenoides dalli)), mysticetes (North Pacific right 
whales (Eubalaena japonica), gray whales (Eschrichtius robustus), 
humpback whales[ast] (Megaptera novaeangliae), minke whales[ast] 
(Balaenoptera acutorostrata), sei whales (Balaenoptera borealis), fin 
whales[ast] (Balaenoptera physalus), and blue whales ((Balaenoptera 
musculus)), pinnipeds (Steller sea lion (Eumetopias jubatus), harbor 
seal (Phoca vitulina) and northern fur seal (Callorhinus ursinus)). Of 
the 18 cetacean species in the area, several (designated by an [ast]) 
are commonly found in the activity area and may be affected by the 
proposed acitivty. Of the three species of pinnipeds that could 
potentially occur in SE Alaska, only the Steller sea lion and harbor 
seal are likely to be present. The northern fur seal inhabits the 
Bering Sea during the summer and is generally found in SE Alaska in low 
numbers during the winter, and during the northward migration in 
spring. Sea otters generally inhabit coastal waters within the 40-m 
(131-ft) depth contour (Riedman and Estes, 1990) and may be encountered 
in coastal areas of the study area. More detailed information on these 
species is contained in the L-DEO application and additional 
information is contained in Angliss and Lodge, 2002 which are available 
at: http://www.nmfs.noaa.gov/prot_res/PR2/Small_Take/smalltake_info.htm#applications, and http://www.nmfs.noaa.gov/prot_res/PR2/Stock_Assessment_Program/sars.html, respectively.

Potential Effects on Marine Mammals

    As outlined in several previous NMFS documents, the effects of 
noise on marine mammals are highly variable, and can be categorized as 
follows (based on Richardson et al., 1995):
    (1) The noise may be too weak to be heard at the location of the 
animal (i.e., lower than the prevailing ambient noise level, the 
hearing threshold of the animal at relevant frequencies, or both);
    (2) The noise may be audible but not strong enough to elicit any 
overt behavioral response;
    (3) The noise may elicit reactions of variable conspicuousness and 
variable relevance to the well being of the marine mammal; these can 
range from temporary alert responses to active avoidance reactions such 
as vacating an area at least until the noise event ceases;
    (4) Upon repeated exposure, a marine mammal may exhibit diminishing 
responsiveness (habituation), or disturbance effects may persist; the 
latter is most likely with sounds that are highly variable in 
characteristics, infrequent and unpredictable in occurrence, and 
associated with situations that a marine mammal perceives as a threat;
    (5) Any anthropogenic noise that is strong enough to be heard has 
the potential to reduce (mask) the ability of a marine mammal to hear 
natural sounds at similar frequencies, including calls from 
conspecifics, and underwater environmental sounds such as surf noise;
    (6) If mammals remain in an area because it is important for 
feeding, breeding or some other biologically important purpose even 
though there is chronic exposure to noise, it is possible that there 
could be noise-induced physiological stress; this might in turn have 
negative effects on the well-being or reproduction of the animals 
involved; and
    (7) Very strong sounds have the potential to cause temporary or 
permanent reduction in hearing sensitivity. In terrestrial mammals, and 
presumably marine mammals, received sound levels must far exceed the 
animal's hearing threshold for there to be any temporary threshold 
shift (TTS) in its hearing ability. For transient sounds, the sound 
level necessary to cause TTS is inversely related to the duration of 
the sound. Received sound levels must be even higher for there to be 
risk of permanent hearing impairment. In addition, intense acoustic or 
explosive events may cause trauma to tissues associated with organs 
vital for hearing, sound production, respiration and other functions. 
This trauma may include minor to severe hemorrhage.

Effects of Seismic Surveys on Marine Mammals

    The L-DEO application provides the following information on what is 
known about the effects on marine mammals of the types of seismic 
operations planned by L-DEO. The types of effects considered here are 
(1) masking, (2) disturbance, and (3) potential hearing impairment and 
other physical effects. Additional discussion on species specific 
effects can be found in the L-DEO application.

Masking

    Masking effects of pulsed sounds on marine mammal calls and other 
natural sounds are expected to be limited, although there are very few 
specific data on this. Seismic sounds are short pulses generally 
occurring for less than 1 sec every 20 or 60-90 sec during this 
project. Sounds from the multibeam sonar are very short pulses, 
occurring for 1-10 msec once every 1 to 15 sec, depending on water 
depth. (During operations in deep water, the duration of each pulse 
from the multibeam sonar as received at any one location would actually 
be only \1/5\ or at most \2/5\ of 1-10 msec, given the segmented nature 
of the pulses.) Some whales are known to continue calling in the 
presence of seismic pulses. Their calls can be heard between the 
seismic pulses (Richardson et al., 1986; McDonald et al., 1995, Greene 
et al., 1999). Although there has been one report that sperm whales 
cease calling when exposed to pulses from a very distant seismic ship 
(Bowles et al., 1994), a recent study reports that sperm whales 
continued calling in the presence of seismic pulses (Madsen et al., 
2002). Given the small source planned for use during this survey, there 
is even less potential for masking of sperm whale calls during the 
present study than in most seismic surveys. Masking effects of seismic 
pulses are expected to be negligible in the case of the smaller 
odontocete cetaceans, given the intermittent nature of seismic pulses 
and the relatively low source level of the airguns to be used in the 
GOA. Also, the sounds important to small odontocetes are predominantly 
at much higher frequencies than are airgun sounds.
    Most of the energy in the sound pulses emitted by airgun arrays is 
at low frequencies, with strongest spectrum levels below 200 Hz and 
considerably lower spectrum levels above 1000 Hz. These frequencies are 
mainly used by mysticetes, but not by odontocetes or pinnipeds. An 
industrial sound source will reduce the effective communication or 
echolocation distance only if its frequency is close to that of the 
cetacean signal. If little or no overlap occurs between the industrial 
noise and the frequencies used, as in the case of many marine mammals 
vs. airgun sounds, communication and echolocation are not expected to 
be disrupted. Furthermore, the discontinuous nature of seismic pulses 
makes significant masking effects unlikely even for mysticetes.
    A few cetaceans are known to increase the source levels of their 
calls in the presence of elevated sound levels, or possibly to shift 
their peak frequencies in response to strong sound signals (Dahlheim, 
1987; Au, 1993; Lesage et al., 1999; Terhune, 1999; as

[[Page 58142]]

reviewed in Richardson et al., 1995). These studies involved exposure 
to other types of anthropogenic sounds, not seismic pulses, and it is 
not known whether these types of responses ever occur upon exposure to 
seismic sounds. If so, these adaptations, along with directional 
hearing, pre-adaptation to tolerate some masking by natural sounds 
(Richardson et al., 1995) and the relatively low-power acoustic sources 
being used in this survey, would all reduce the importance of masking 
marine mammal vocalizations.

Disturbance by Seismic Surveys

    Disturbance includes a variety of effects, including subtle changes 
in behavior, more conspicuous dramatic changes in activities, and 
displacement. However, there are difficulties in defining which marine 
mammals should be counted as ``taken by harassment''. For many species 
and situations, scientists do not have detailed information about their 
reactions to noise, including reactions to seismic (and sonar) pulses. 
Behavioral reactions of marine mammals to sound are difficult to 
predict. Reactions to sound, if any, depend on species, state of 
maturity, experience, current activity, reproductive state, time of 
day, and many other factors. If a marine mammal does react to an 
underwater sound by changing its behavior or moving a small distance, 
the impacts of the change may not rise to the level of a disruption of 
a behavioral pattern. However, if a sound source would displace marine 
mammals from an important feeding or breeding area for a prolonged 
period, such a disturbance would constitute Level B harassment. Given 
the many uncertainties in predicting the quantity and types of impacts 
of noise on marine mammals, scientists often resort to estimating how 
many mammals may be present within a particular distance of industrial 
activities or exposed to a particular level of industrial sound. This 
likely overestimates the numbers of marine mammals that are affected in 
some biologically meaningful manner.
    The sound criteria used to estimate how many marine mammals might 
be harassed behaviorally by the seismic survey are based on behavioral 
observations during studies of several species. However, information is 
lacking for many species. More detailed information on potential 
disturbance effects on baleen whales, toothed whales, and pinnipeds can 
be found on pages 36-38 and Appendix A in L-DEO's application.

Hearing Impairment and Other Physical Effects

    Temporary or permanent hearing impairment is a possibility when 
marine mammals are exposed to very strong sounds, but there has been no 
specific documentation of this for marine mammals exposed to airgun 
pulses. Current NMFS policy precautionarily sets impulsive sounds equal 
to or greater than 180 and 190 dB re 1 microPa (rms) as the exposure 
thresholds for onset of Level A harassment for cetaceans and pinnipeds, 
respectively (NMFS, 2000). Those criteria have been used in defining 
the safety (shut-down) radii for seismic surveys. However, those 
criteria were established before there were any data on the minimum 
received levels of sounds necessary to cause auditory impairment in 
marine mammals. As discussed in the L-DEO application and summarized 
here,
    1. The 180 dB criterion for cetaceans is probably quite 
precautionary, i.e., lower than necessary to avoid TTS let alone 
permanent auditory injury, at least for delphinids.
    2. The minimum sound level necessary to cause permanent hearing 
impairment is higher, by a variable and generally unknown amount, than 
the level that induces barely-detectable TTS.
    3. The level associated with the onset of TTS is often considered 
to be a level below which there is no danger of permanent damage.
    Given the small size of the GI airguns, along with the planned 
monitoring and mitigation measures, there is little likelihood that any 
marine mammals will be exposed to sounds sufficiently strong to cause 
even the mildest (and reversible) form of hearing impairment. Several 
aspects of the planned monitoring and mitigation measures for this 
project are designed to detect marine mammals occurring near the 2 GI-
airguns (and multibeam bathymetric sonar), and to avoid exposing them 
to sound pulses that might cause hearing impairment. In addition, many 
cetaceans are likely to show some avoidance of the area with ongoing 
seismic operations. In these cases, the avoidance responses of the 
animals themselves will reduce or avoid the possibility of hearing 
impairment.
    Non-auditory physical effects may also occur in marine mammals 
exposed to strong underwater pulsed sound. Possible types of non-
auditory physiological effects or injuries that theoretically might 
occur in mammals close to a strong sound source include stress, 
neurological effects, bubble formation, resonance effects, and other 
types of organ or tissue damage. It is possible that some marine mammal 
species (i.e., beaked whales) may be especially susceptible to injury 
and/or stranding when exposed to strong pulsed sounds. However, L-DEO 
and NMFS believe that it is especially unlikely that any of these non-
auditory effects would occur during the proposed survey given the small 
size of the sound sources, the brief duration of exposure of any given 
mammal, and the planned mitigation and monitoring measures. The 
following paragraphs discuss the possibility of TTS, permanent 
threshold shift (PTS), and non-auditory physical effects.

Temporary Threshold Shift (TTS)

    TTS is the mildest form of hearing impairment that can occur during 
exposure to a strong sound (Kryter, 1985). When an animal experiences 
TTS, its hearing threshold rises and a sound must be stronger in order 
to be heard. TTS can last from minutes or hours to (in cases of strong 
TTS) days. Richardson et al. (1995) notes that the magnitude of TTS 
depends on the level and duration of noise exposure, among other 
considerations. For sound exposures at or somewhat above the TTS 
threshold, hearing sensitivity recovers rapidly after exposure to the 
noise ends. Little data on sound levels and durations necessary to 
elicit mild TTS have been obtained for marine mammals.
    For toothed whales exposed to single short pulses, the TTS 
threshold appears to be, to a first approximation, a function of the 
energy content of the pulse (Finneran et al., 2002). Given the 
available data, the received level of a single seismic pulse might need 
to be on the order of 210 dB re 1 microPa rms (approx. 221 226 dB pk 
pk) in order to produce brief, mild TTS. Exposure to several seismic 
pulses at received levels near 200 205 dB (rms) might result in slight 
TTS in a small odontocete, assuming the TTS threshold is (to a first 
approximation) a function of the total received pulse energy (Finneran 
et al., 2002). Seismic pulses with received levels of 200 205 dB or 
more are usually restricted to a zone of no more than 100 m (328 ft) 
around a seismic vessel operating a large array of airguns. Such sound 
levels would be limited to distances within a few meters of the small 
airgun source to be used during this project.
    There are no data, direct or indirect, on levels or properties of 
sound that are required to induce TTS in any baleen whale. However, TTS 
is not expected to occur during this survey given the small

[[Page 58143]]

size of the source, and the strong likelihood that baleen whales would 
avoid the approaching airguns (or vessel) before being exposed to 
levels high enough for there to be any possibility of TTS.
    TTS thresholds for pinnipeds exposed to brief pulses (single or 
multiple) have not been measured, although exposures up to 183 db re 1 
microPa (rms) have been shown to be insufficient to induce TTS in 
California sea lions (Finneran et al., 2003). However, prolonged 
exposures show that some pinnipeds may incur TTS at somewhat lower 
received levels than do small odontocetes exposed for similar durations 
(Kastak et al., 1999; Ketten et al., 2001; Au et al., 2000).
    A marine mammal within a zone of <=100 m (<= 328 ft) around a 
typical large array of operating airguns might be exposed to a few 
seismic pulses with levels of [gteqt]205 dB, and possibly more pulses 
if the mammal moved with the seismic vessel. Also, around smaller 
arrays, such as the 2 GI-airgun proposed for use during this survey, a 
marine mammal would need to be even closer to the source to be exposed 
to levels [gteqt]205 dB, at least in waters greater than 100 m (328 ft) 
deep. However, as noted previously, most cetacean species tend to avoid 
operating airguns, although not all individuals do so. In addition, 
ramping up airgun arrays, which is standard operational protocol for L-
DEO and other seismic operators, should allow cetaceans to move away 
from the seismic source and avoid being exposed to the full acoustic 
output of the airgun array. It is unlikely that these cetaceans would 
be exposed to airgun pulses at a sufficiently high level for a 
sufficiently long period to cause more than mild TTS, given the 
relative movement of the vessel and the marine mammal. However, TTS 
would be more likely in any odontocetes that bow-ride or otherwise 
linger near the airguns. Odontocetes would be at or above the surface 
while bow-riding, and thus not exposed to strong sound pulses given the 
pressure-release effect at the surface. However, bow-riding animals 
generally dive below the surface intermittently. If they did so while 
bow-riding near airguns, they would be exposed to strong sound pulses, 
possibly repeatedly. If some cetaceans did incur TTS through exposure 
to airgun sounds, this would very likely be a temporary and reversible 
phenomenon.
    NMFS currently believes that, whenever possible to avoid Level A 
harassment, cetaceans should not be exposed to pulsed underwater noise 
at received levels exceeding 180 dB re 1 microPa (rms). The 
corresponding limit for pinnipeds has been set at 190 dB. The predicted 
180- and 190-dB received-level distances for the airgun arrays operated 
by L-DEO during this activity are summarized elsewhere in this 
document. These sound levels are not considered to be the levels at or 
above which TTS might occur. Rather, they are the received levels above 
which, in the view of a panel of bioacoustics specialists convened by 
NMFS (at a time before TTS measurements for marine mammals started to 
become available), one could not be certain that there would be no 
injurious effects, auditory or otherwise, to marine mammals. As noted 
here, TTS data that are now available imply that, at least for 
dolphins, TTS is unlikely to occur unless the dolphins are exposed to 
airgun pulses substantially stronger that 180 dB re 1 microPa (rms).
    It has also been shown that most whales tend to avoid ships and 
associated seismic operations. Thus, whales will likely not be exposed 
to such high levels of airgun sounds. Because of the slow ship speed, 
any whales close to the trackline could move away before the sounds 
become sufficiently strong for there to be any potential for hearing 
impairment. Therefore, there is little potential for whales being close 
enough to an array to experience TTS. In addition, as mentioned 
previously, ramping up the 2 GI-airgun array, which has become standard 
operational protocol for many seismic operators including L-DEO, should 
allow cetaceans to move away from the seismic source and to avoid being 
exposed to the full acoustic output of the GI airguns.

Permanent Threshold Shift (PTS)

    When PTS occurs, there is physical damage to the sound receptors in 
the ear. In some cases, there can be total or partial deafness, while 
in other cases, the animal has an impaired ability to hear sounds in 
specific frequency ranges. Physical damage to a mammal's hearing 
apparatus can occur if it is exposed to sound impulses that have very 
high peak pressures, especially if they have very short rise times 
(time required for sound pulse to reach peak pressure from the baseline 
pressure). Such damage can result in a permanent decrease in functional 
sensitivity of the hearing system at some or all frequencies.
    Single or occasional occurrences of mild TTS are not indicative of 
permanent auditory damage in terrestrial mammals. However, very 
prolonged exposure to sound strong enough to elicit TTS, or shorter-
term exposure to sound levels well above the TTS threshold, can cause 
PTS, at least in terrestrial mammals (Kryter, 1985). Relationships 
between TTS and PTS thresholds have not been studied in marine mammals 
but are assumed to be similar to those in humans and other terrestrial 
mammals. The low-to-moderate levels of TTS that have been induced in 
captive odontocetes and pinnipeds during recent controlled studies of 
TTS have been confirmed to be temporary, with no measurable residual 
PTS (Kastak et al., 1999; Schlundt et al., 2000; Finneran et al., 2002; 
Nachtigall et al., 2003). In terrestrial mammals, the received sound 
level from a single non-impulsive sound exposure must be far above the 
TTS threshold for any risk of permanent hearing damage (Kryter, 1994; 
Richardson et al., 1995). For impulse sounds with very rapid rise times 
(e.g., those associated with explosions or gunfire), a received level 
not greatly in excess of the TTS threshold may start to elicit PTS. 
Rise times for airgun pulses are rapid, but less rapid than for 
explosions.
    Some factors that contribute to onset of PTS are as follows: (1) 
exposure to single very intense noises, (2) repetitive exposure to 
intense sounds that individually cause TTS but not PTS, and (3) 
recurrent ear infections or (in captive animals) exposure to certain 
drugs.
    Cavanagh (2000) has reviewed the thresholds used to define TTS and 
PTS. Based on his review and SACLANT (1998), it is reasonable to assume 
that PTS might occur at a received sound level 20 dB or more above that 
which induces mild TTS. However, for PTS to occur at a received level 
only 20 dB above the TTS threshold, it is probable that the animal 
would have to be exposed to the strong sound for an extended period.
    Sound impulse duration, peak amplitude, rise time, and number of 
pulses are the main factors thought to determine the onset and extent 
of PTS. Based on existing data, Ketten (1994) has noted that the 
criteria for differentiating the sound pressure levels that result in 
PTS (or TTS) are location and species-specific. PTS effects may also be 
influenced strongly by the health of the receiver's ear.
    Given that marine mammals are unlikely to be exposed to received 
levels of seismic pulses that could cause TTS, it is highly unlikely 
that they would sustain permanent hearing impairment. If we assume that 
the TTS threshold for exposure to a series of seismic pulses may be on 
the order of 220 dB re 1 microPa (pk-pk) in odontocetes, then the PTS 
threshold might be about 240

[[Page 58144]]

dB re 1 microPa (pk-pk). In the units used by geophysicists, this is 10 
bar-m. Such levels are found only in the immediate vicinity of the 
largest airguns (Richardson et al., 1995; Caldwell and Dragoset, 2000). 
However, it is very unlikely that an odontocete would remain within a 
few meters of a large airgun for sufficiently long to incur PTS. The 
TTS (and thus PTS) thresholds of baleen whales and pinnipeds may be 
lower, and thus may extend to a somewhat greater distance. However, 
baleen whales generally avoid the immediate area around operating 
seismic vessels, so it is unlikely that a baleen whale could incur PTS 
from exposure to airgun pulses. Some pinnipeds do not show strong 
avoidance of operating airguns. In summary, it is highly unlikely that 
marine mammals could receive sounds strong enough (and over a 
sufficient period of time) to cause permanent hearing impairment during 
this project. In the proposed project, marine mammals are unlikely to 
be exposed to received levels of seismic pulses strong enough to cause 
TTS and because of the higher level of sound necessary to cause PTS, it 
is even less likely that PTS could occur. This is due to the fact that 
even sound levels immediately adjacent to the 2 GI-airguns may not be 
sufficient to induce PTS because the mammal would not be exposed to 
more than one strong pulse unless it swam alongside an airgun for a 
period of time.

Strandings and Mortality

    Marine mammals close to underwater detonations of high explosives 
can be killed or severely injured, and the auditory organs are 
especially susceptible to injury (Ketten et al., 1993; Ketten, 1995). 
Airgun pulses are less energetic and have slower rise times than 
underwater detonations. While there is no documented evidence that 
airgun arrays can cause serious injury, death, or stranding, the 
association of mass strandings of beaked whales with naval exercises 
and, recently, an L-DEO seismic survey have raised the possibility that 
beaked whales may be especially susceptible to injury and/or stranding 
when exposed to strong pulsed sounds.
    In March 2000, several beaked whales that had been exposed to 
repeated pulses from high intensity, mid-frequency military sonars 
stranded and died in the Providence Channels of the Bahamas Islands, 
and were subsequently found to have incurred cranial and ear damage 
(NOAA and USN, 2001). Based on post-mortem analyses, it was concluded 
that an acoustic event caused hemorrhages in and near the auditory 
region of some beaked whales. These hemorrhages occurred before death. 
They would not necessarily have caused death or permanent hearing 
damage, but could have compromised hearing and navigational ability 
(NOAA and USN, 2001). The researchers concluded that acoustic exposure 
caused this damage and triggered stranding, which resulted in 
overheating, cardiovascular collapse, and physiological shock that 
ultimately led to the death of the stranded beaked whales. During the 
event, five naval vessels used their AN/SQS-53C or -56 hull-mounted 
active sonars for a period of 16 hours. The sonars produced narrow 
(<100 Hz) bandwidth signals at center frequencies of 2.6 and 3.3 kHz (-
53C), and 6.8 to 8.2 kHz (-56). The respective source levels were 
usually 235 and 223 dB re 1 [micro] Pa, but the -53C briefly operated 
at an unstated but substantially higher source level. The unusual 
bathymetry and constricted channel where the strandings occurred were 
conducive to channeling sound. This, and the extended operations by 
multiple sonars, apparently prevented escape of the animals to the open 
sea. In addition to the strandings, there are reports that beaked 
whales were no longer present in the Providence Channel region after 
the event, suggesting that other beaked whales either abandoned the 
area or perhaps died at sea (Balcomb and Claridge, 2001).
    Other strandings of beaked whales associated with operation of 
military sonars have also been reported (e.g., Simmonds and Lopez-
Jurado, 1991; Frantzis, 1998). In these cases, it was not determined 
whether there were noise-induced injuries to the ears or other organs. 
Another stranding of beaked whales (15 whales) happened on 24-25 
September 2002 in the Canary Islands, where naval maneuvers were taking 
place in the area. Jepson et al. (2003) concluded that cetaceans might 
be subject to decompression injury in some situations. If so, this 
might occur if the mammals ascend unusually quickly when exposed to 
aversive sounds. Previously, it was widely assumed that diving marine 
mammals are not subject to decompression injury (the bends or air 
embolism).
    It is important to note that seismic pulses and mid-frequency sonar 
pulses are quite different. Sounds produced by the types of airgun 
arrays used to profile sub-sea geological structures are broadband with 
most of the energy below 1 kHz. Typical military mid-frequency sonars 
operate at frequencies of 2 to 10 kHz, generally with a relatively 
narrow bandwidth at any one time (though the center frequency may 
change over time). Because seismic and sonar sounds have considerably 
different characteristics and duty cycles, it is not appropriate to 
assume that there is a direct connection between the effects of 
military sonar and seismic surveys on marine mammals. However, evidence 
that sonar pulses can in special circumstances lead to hearing damage 
and, indirectly, to mortality suggests that caution is warranted when 
dealing with exposure of marine mammals to any high-intensity pulsed 
sound.
    In addition to the sonar-related strandings, there was a September, 
2002 stranding of two Cuvier's beaked whales in the Gulf of California 
(Mexico) when a seismic survey by the Ewing was underway in the general 
area (Malakoff, 2002). The airgun array in use during that project was 
the Ewing's 20-gun 8490-in\3\ array. This might be a first indication 
that seismic surveys can have effects, at least on beaked whales, 
similar to the suspected effects of naval sonars. However, the evidence 
linking the Gulf of California strandings to the seismic surveys is 
inconclusive, and to date is not based on any physical evidence 
(Hogarth, 2002; Yoder, 2002). The ship was also operating its multi-
beam bathymetric sonar at the same time but this sonar had much less 
potential than these naval sonars to affect beaked whales. Although the 
link between the Gulf of California strandings and the seismic (plus 
multi-beam sonar) survey is inconclusive, this event plus the various 
incidents involving beaked whale strandings associated with naval 
exercises suggests a need for caution in conducting seismic surveys in 
areas occupied by beaked whales.

Non-auditory Physiological Effects

    Possible types of non-auditory physiological effects or injuries 
that might theoretically occur in marine mammals exposed to strong 
underwater sound might include stress, neurological effects, bubble 
formation, resonance effects, and other types of organ or tissue 
damage. There is no evidence that any of these effects occur in marine 
mammals exposed to sound from airgun arrays. However, there have been 
no direct studies of the potential for airgun pulses to elicit any of 
these effects. If any such effects do occur, they would probably be 
limited to unusual situations when animals might be exposed at close 
range for unusually long periods.
    Long-term exposure to anthropogenic noise may have the potential to 
cause physiological stress that could affect the

[[Page 58145]]

health of individual animals or their reproductive potential, which 
could theoretically cause effects at the population level (Gisner 
(ed.), 1999). However, there is essentially no information about the 
occurrence of noise-induced stress in marine mammals. Also, it is 
doubtful that any single marine mammal would be exposed to strong 
seismic sounds for sufficiently long that significant physiological 
stress would develop. This is particularly so in the case of broad-
scale seismic surveys where the tracklines are generally not as closely 
spaced as in many oil and gas industry seismic surveys.
    Gas-filled structures in marine animals have an inherent 
fundamental resonance frequency. If stimulated at this frequency, the 
ensuing resonance could cause damage to the animal. There may also be a 
possibility that high sound levels could cause bubble formation in the 
blood of diving mammals that in turn could cause an air embolism, 
tissue separation, and high, localized pressure in nervous tissue 
(Gisner (ed), 1999; Houser et al., 2001). In 2002, NMFS held a workshop 
(Gentry (ed.) 2002) to discuss whether the stranding of beaked whales 
in the Bahamas in 2000 might have been related to air cavity resonance 
or bubble formation in tissues caused by exposure to noise from naval 
sonar. A panel of experts concluded that resonance in air-filled 
structures was not likely to have caused this stranding. Among other 
reasons, the air spaces in marine mammals are too large to be 
susceptible to resonant frequencies emitted by mid- or low-frequency 
sonar; lung tissue damage has not been observed in any mass, multi-
species stranding of beaked whales; and the duration of sonar pings is 
likely too short to induce vibrations that could damage tissues (Gentry 
(ed.), 2002). Opinions were less conclusive about the possible role of 
gas (nitrogen) bubble formation/growth in the Bahamas stranding of 
beaked whales. Workshop participants did not rule out the possibility 
that bubble formation/growth played a role in the stranding and 
participants acknowledged that more research is needed in this area. 
The only available information on acoustically-mediated bubble growth 
in marine mammals is modeling that assumes prolonged exposure to sound.
    In summary, little is known about the potential for seismic survey 
sounds to cause either auditory impairment or other non-auditory 
physical effects in marine mammals. Available data suggest that such 
effects, if they occur at all, would be limited to short distances from 
the sound source. However, the available data do not allow for 
meaningful quantitative predictions of the numbers (if any) of marine 
mammals that might be affected in these ways. Marine mammals that show 
behavioral avoidance of seismic vessels, including most baleen whales, 
some odontocetes, and some pinnipeds, are unlikely to incur auditory 
impairment or other physical effects.

Possible Effects of Mid-frequency Sonar Signals

    A multi-beam bathymetric sonar (Atlas Hydrosweep DS-2 (15.5-kHz) or 
Simrad EM1002 (95 kHz)) and a sub-bottom profiler will be operated from 
the source vessel essentially continuously during the planned survey. 
Details about these sonars were provided previously in this document.
    Navy sonars that have been linked to avoidance reactions and 
stranding of cetaceans generally (1) are more powerful than the Atlas 
Hydrosweep or EM1002 sonars, (2) have a longer pulse duration, and (3) 
are directed close to horizontally (vs. downward for the Atlas 
Hydrosweep and EM1002). The area of possible influence for the Ewing's 
sonars is much smaller - a narrow band below the source vessel. For the 
Hydrosweep there is no horizontal propagation as these signals project 
at an angle of approximately 45 degrees from the ship. For the deep-
water mode, under the ship the 160- and 180-dB zones are estimated to 
be 3200 m (10500 ft) and 610 m (2000 ft), respectively. However, the 
beam width of the Hydrosweep signal is only 2.67 degrees fore and aft 
of the vessel, meaning that a marine mammal diving could receive at 
most 1-2 signals from the Hydrosweep and a marine mammal on the surface 
would be unaffected. Marine mammals that do encounter the bathymetric 
sonars at close range are unlikely to be subjected to repeated pulses 
because of the narrow fore-aft width of the beam, and will receive only 
limited amounts of pulse energy because of the short pulses and vessel 
speed. Therefore, as harassment or injury from pulsed sound is a 
function of total energy received, the actual harassment or injury 
threshold for the bathymetric sonar signals (approximately 10 ms) would 
be at a much higher dB level than that for longer duration pulses such 
as seismic signals. As a result, NMFS believes that marine mammals are 
unlikely to be harassed or injured from the multibeam sonar.

Masking by Mid-frequency Sonar Signals

    Marine mammal communications will not be masked appreciably by the 
multibeam sonar signals or the sub-bottom profiler given the low duty 
cycle and directionality of the sonars and the brief period when an 
individual mammal is likely to be within its beam. Furthermore, in the 
case of baleen whales, the sonar signals from the Hydrosweep sonar do 
not overlap with the predominant frequencies in the calls, which would 
avoid significant masking. The 95-kHz pulses from the EM1002 sonar will 
be inaudible to baleen whales and pinnipeds.
    For the sub-bottom profiler and 12-kHz pinger, marine mammal 
communications will not be masked appreciably because of their 
relatively low power output, low duty cycle, directionality (for the 
profiler), and the brief period when an individual mammal may be within 
the sonar's beam. In the case of most odonotocetes, the sonar signals 
from the profiler do not overlap with the predominant frequencies of 
their calls. In the case of mysticetes, the pulses from the pinger do 
not overlap with their predominant frequencies.

Behavioral Responses Resulting from Mid-Frequency Sonar Signals

    Behavioral reactions of free-ranging marine mammals to military and 
other sonars appear to vary by species and circumstance. Observed 
reactions have included silencing and dispersal by sperm whales 
(Watkins et al., 1985), increased vocalizations and no dispersal by 
pilot whales (Rendell and Gordon, 1999), and the previously-mentioned 
beachings by beaked whales. Also, Navy personnel have described 
observations of dolphins bow-riding adjacent to bow-mounted mid-
frequency sonars during sonar transmissions. However, all of these 
observations are of limited relevance to the present situation. Pulse 
durations from these sonars were much longer than those of the L-DEO 
multibeam sonar, and a given mammal would have received many pulses 
from the naval sonars. During L-DEO's operations, the individual pulses 
will be very short, and a given mammal would not receive many of the 
downward-directed pulses as the vessel passes by.
    Captive bottlenose dolphins and a white whale exhibited changes in 
behavior when exposed to 1-sec pulsed sounds at frequencies similar to 
those that will be emitted by the multi-beam sonar used by L-DEO and to 
shorter broadband pulsed signals. Behavioral changes typically involved 
what appeared to be deliberate attempts to avoid the sound exposure 
(Schlundt et al., 2000; Finneran et al., 2002). The relevance of these 
data to free-ranging odontocetes is uncertain and in any case

[[Page 58146]]

the test sounds were quite different from a bathymetric sonar in either 
duration or bandwidth.
    L-DEO and NMFS are not aware of any data on the reactions of 
pinnipeds to sonar sounds at frequencies similar to those of the 15.5 
kHz frequency of the Ewing's multibeam sonar. Based on observed 
pinniped responses to other types of pulsed sounds, and the likely 
brevity of exposure to the bathymetric sonar sounds, pinniped reactions 
are expected to be limited to startle or otherwise brief responses of 
no lasting consequences to the individual animals. As mentioned, the 
95-kHz sounds from the EM1002 will be inaudible to pinnipeds and to 
baleen whales, so it will have no disturbance effects on those groups 
of mammals. The pulsed signals from the sub-bottom profiler and pinger 
are much weaker than those from the airgun array and the multibeam 
sonar. Therefore, significant behavioral responses are not expected.

Hearing Impairment and Other Physical Effects from Mid-Frequency Sonar 
Signals

    Given recent stranding events that have been associated with the 
operation of naval sonar, there is much concern that sonar noise can 
cause serious impacts to marine mammals (for discussion see Effects of 
Seismic Surveys). However, the multi-beam sonars proposed for use by L-
DEO are quite different than sonars used for navy operations. Pulse 
duration of the bathymetric sonars is very short relative to the naval 
sonars. Also, at any given location, an individual marine mammal would 
be in the beam of the multi-beam sonar for a very limited time given 
the generally downward orientation of the beam and its narrow fore-aft 
beam-width. (Navy sonars often use near-horizontally-directed sound.) 
These factors would all reduce the sound energy received from the 
multi-beam sonar rather drastically relative to that from the sonars 
used by the Navy. Therefore, hearing impairment by multi-beam 
bathymetric sonar is unlikely.
    Source levels of the sub-bottom profiler are much lower than those 
of the airguns and the multi-beam sonar. Sound levels from a sub-bottom 
profiler similar to the one on the Ewing were estimated to decrease to 
180 dB re 1 microPa (rms) at 8 m (26 ft) horizontally from the source 
(Burgess and Lawson, 2000), and at approximately 18 m downward from the 
source. Furthermore, received levels of pulsed sounds that are 
necessary to cause temporary or especially permanent hearing impairment 
in marine mammals appear to be higher than 180 dB (see earlier 
discussion). Thus, it is unlikely that the sub-bottom profiler produces 
pulse levels strong enough to cause hearing impairment or other 
physical injuries even in an animal that is (briefly) in a position 
near the source.
    The sub-bottom profiler is usually operated simultaneously with 
other higher-power acoustic sources. Many marine mammals will move away 
in response to the approaching higher-power sources or the vessel 
itself before the mammals would be close enough for there to be any 
possibility of effects from the less intense sounds from the sub-bottom 
profiler. In the case of mammals that do not avoid the approaching 
vessel and its various sound sources, mitigation measures that would be 
applied to minimize effects of the higher-power sources would further 
reduce or eliminate any minor effects of the sub-bottom profiler.
    The 12-kHz pinger is unlikely to cause hearing impairment or 
physical injuries even in an animal that is in a position near the 
source because is does not produce strong pulse levels.

Estimates of Take by Harassment for the GOA Seismic Survey

    Although information contained in this document indicates that 
injury to marine mammals from seismic sounds potentially occurs at 
sound pressure levels significantly higher than 180 and 190 dB, NMFS' 
current criteria for onset of Level A harassment of cetaceans and 
pinnipeds from impulse sound are, respectively, 180 and 190 re 1 
microPa rms. The rms level of a seismic pulse is typically about 10 dB 
less than its peak level and about 16 dB less than its pk-pk level 
(Greene, 1997; McCauley et al., 1998; 2000a). The criterion for Level B 
harassment onset is 160 dB.
    Given the required mitigation (see Mitigation later in this 
document), all anticipated takes involve a temporary change in behavior 
that may constitute Level B harassment. The required mitigation 
measures will minimize or eliminate the possibility of Level A 
harassment or mortality. L-DEO has calculated the ``best estimates'' 
for the numbers of animals that could be taken by Level B harassment 
during the proposed GOA seismic survey using data on marine mammal 
density and abundance from marine mammal surveys in the region, and 
estimates of the size of the affected area, as shown in the predicted 
RMS radii table (see Table 1).
    These estimates are based on a consideration of the number of 
marine mammals that might be exposed to sound levels greater than 160 
dB, the criterion for the onset of Level B harassment, by operations 
with the 2 GI-gun array planned to be used for this project. The 
anticipated zone of influence of the multi-beam sonar is less than that 
for the airguns, so it is assumed that any marine mammals close enough 
to be affected by the multi-beam sonar would already be affected by the 
airguns. Therefore, no additional incidental takings are included for 
animals that might be affected by the multi-beam sonar.
    Table 2 explains the corrected density estimates as well as the 
best estimate of the numbers of each species that would be exposed to 
seismic sounds greater than 160 dB. A detailed description on the 
methodology used by L-DEO to arrive at the estimates of Level B 
harassment takes that are provided in Table 2 can be found in L-DEO's 
IHA application for the GOA survey.

[[Page 58147]]

[GRAPHIC] [TIFF OMITTED] TN29SE04.000


[[Page 58148]]



Conclusions

Effects on Cetaceans

    Strong avoidance reactions by several species of mysticetes to 
seismic vessels have been observed at ranges up to 6-8 km (3.2-4.3 nm) 
and occasionally as far as 20-30 km (10.8-16.2 nm) from the source 
vessel. However, reactions at the longer distances appear to be 
atypical of most species and situations, particular when feeding whales 
are involved. Many of the mysticetes that will be encountered in SE 
Alaska at the time of the proposed seismic survey will be feeding. In 
addition, the estimated numbers presented in Table 2 are considered 
overestimates of actual numbers that may be harassed. The estimated 
160-dB radii used here are probably overestimates of the actual 160-dB 
radii at water depths [gteqt]100 m (328 ft) based on the few 
calibration data obtained in deep water (Tolstoy et al., 2004).
    Odontocete reactions to seismic pulses, or at least the reactions 
of dolphins, are expected to extend to lesser distances than are those 
of mysticetes. Odontocete low-frequency hearing is less sensitive than 
that of mysticetes, and dolphins are often seen from seismic vessels. 
In fact, there are documented instances of dolphins approaching active 
seismic vessels. However, dolphins as well as some other types of 
odontocetes sometimes show avoidance responses and/or other changes in 
behavior when near operating seismic vessels.
    Taking into account the small size and the relatively low sound 
output of the 2 GI-guns to be used, and the mitigation measures that 
are planned, effects on cetaceans are generally expected to be limited 
to avoidance of a small area around the seismic operation and short-
term changes in behavior, falling within the MMPA definition of Level B 
harassment. Furthermore, the estimated numbers of animals potentially 
exposed to sound levels sufficient to cause appreciable disturbance are 
very low percentages of the affected populations.
    Based on the 160-dB criterion, the best estimates of the numbers of 
individual cetaceans that may be exposed to sounds [gteqt]160 dB re 1 
microPa (rms) represent 0 to 1.1 percent of the populations of each 
species in the North Pacific Ocean (Table 2). For species listed as 
endangered under the ESA, this includes no North Pacific right whales 
or blue whales; <=0.01 percent of the Northeast Pacific population of 
sperm whales; 1.1 percent of the humpback whale population; and 0.8 
percent of the fin whale population (Table 2). In the cases of belugas, 
beaked whales, and sperm whales, these potential reactions are expected 
to involve no more than very small numbers (0 to 11) of individual 
cetaceans. Humpback and fin whales are the endangered cetacean species 
that are most likely to be exposed and their Northeast Pacific 
populations are approximately 6000 (Caretta et al., 2002) and 10970 
(Ohsumi and Wada, 1974), respectively.
    It is highly unlikely that any North Pacific right whales will be 
exposed to seismic sounds [gteqt]160 dB re 1 microPa (rms). This 
conclusion is based on the rarity of this species in SE Alaska and in 
the Northeast Pacific (less than 100, Carretta et al., 2002), and that 
the remnant population of this species apparently migrates to more 
northerly areas during the summer. However, L-DEO has requested an 
authorization to expose up to two North Pacific right whales to 
[gteqt]160 dB, given the possibility (however unlikely) of encountering 
one or more of this endangered species. If a right whale is sighted by 
the vessel-based observers, the 2 GI-airguns will be shut down (not 
just powered down) regardless of the distance of the whale from the 
airguns.
    Substantial numbers of phocoenids and delphinids may be exposed to 
airgun sounds during the proposed seismic studies, but the population 
sizes of species likely to occur in the operating area are large, and 
the numbers potentially affected are small relative to the population 
sizes (Table 2). The best estimates of the numbers of individual Dall's 
and harbor porpoises that might be exposed to [gteqt]160 dB represent 
0.8 percent and 0.4 percent of their Northeast Pacific populations. The 
best estimates of the numbers of individual delphinids that might be 
exposed to sounds [gteqt]170 dB re 1 [micro]Pa (rms) represents much 
less than 0.01 percent of the approximately 600,000 dolphins estimated 
to occur in the Northeast Pacific, and 0 to 0.2 percent of the 
populations of each species occurring there (Table 2).
    Varying estimates of the numbers of marine mammals that might be 
exposed to sounds from the 2 GI-airguns during the 2004 seismic surveys 
off SW Alaska have been presented, depending on the specific exposure 
criteria, calculation procedures (exposures vs. individuals), and 
density criteria used (best vs. maximum). The requested ``take 
authorization'' for each species is based on the estimated maximum 
number of exposures to [gteqt]160 dB re 1 microPa (rms). That figure 
likely overestimates (in most cases by a large margin) the actual 
number of animals that will be exposed to these sounds; the reasons for 
this have been discussed previously and in L-DEO's application. Even 
so, the estimates for the proposed surveys are quite low percentages of 
the population sizes. Also, these relatively short-term exposures are 
unlikely to result in any long-term negative consequences for the 
individuals or their populations.
    Mitigation measures such as controlled speed, course alteration, 
observers, ramp ups, and shut downs when marine mammals are seen within 
defined ranges (see Mitigation) should further reduce short-term 
reactions, and minimize any effects on hearing sensitivity. In all 
cases, the effects are expected to be short-term, with no lasting 
biological consequence. In light of the type of take expected and the 
small percentages of affected stocks, the action is expected to have no 
more than a negligible impact on the affected species or stocks of 
marine mammals.

Effects on Pinnipeds

    Two pinniped species, the Steller sea lion and the harbor seal, are 
likely to be encountered in the study area. In addition, it is possible 
(although unlikely) that a small number of northern fur seals may be 
encountered. An estimated 1498 harbor seals and 195 Steller sea lions 
(or 1 percent of the Northeast Pacific population) may be exposed to 
airgun sounds during the seismic survey. It is unknown how many of 
these would actually be disturbed, but most likely it would only be a 
small percentage of that population. Similar to cetaceans, the short-
term exposures to airgun and sonar sounds are not expected to result in 
any long-term negative consequences for the individuals or their 
populations.

Potential Effects on Habitat

    The proposed seismic survey will not result in any permanent impact 
on habitats used by marine mammals, or to the food sources they 
utilize. The main impact issue associated with the proposed activity 
will be temporarily elevated noise levels and the associated direct 
effects on marine mammals. The actual area that will be affected by 
coring operations will be a very small fraction of the marine mammal 
habitat and the habitat of their food species in the area; thus, any 
effects are expected to be highly localized and insignificant. Coring 
operations would result in no more than a negligible and highly 
localized short-term disturbance to sediments and benthic organisms. 
The area that might be disturbed is a very small fraction of the 
overall area occupied by a fish or marine mammal species.

[[Page 58149]]

    One of the reasons for the adoption of airguns as the standard 
energy source for marine seismic surveys was that they (unlike the 
explosives used in the distant past) do not result in any appreciable 
fish kill. Various experimental studies showed that airgun discharges 
cause little or no fish kill, and that any injurious effects were 
generally limited to the water within a meter or so of an airgun. 
However, it has recently been found that injurious effects on captive 
fish, especially on fish hearing, may occur to somewhat greater 
distances than previously thought (McCauley et al., 2000a,b, 2002; 
2003). Even so, any injurious effects on fish would be limited to short 
distances from the source. Also, many of the fish that might otherwise 
be within the potential zone of injury are likely to be displaced from 
this region prior to the approach of the airguns through avoidance 
reactions to the passing seismic vessel or to the airgun sounds as 
received at distances beyond the injury radius.
    Fish often react to sounds, especially strong and/or intermittent 
sounds of low frequency. Sound pulses at received levels of 160 dB re 1 
[micro]Pa (peak) may cause subtle changes in behavior. Pulses at levels 
of 180 dB (peak) may cause noticeable changes in behavior (Chapman and 
Hawkins, 1969; Pearson et al., 1992; Skalski et al., 1992). It also 
appears that fish often habituate to repeated strong sounds rather 
rapidly, on time scales of minutes to an hour. However, the habituation 
does not endure, and resumption of the disturbing activity may again 
elicit disturbance responses from the same fish. Fish near the airguns 
are likely to dive or exhibit some other kind of behavioral response. 
This might have short-term impacts on the ability of cetaceans to feed 
near the survey area. However, only a small fraction of the available 
habitat would be ensonified at any given time, and fish species would 
return to their pre-disturbance behavior once the seismic activity 
ceased. Thus, the proposed surveys would have little impact on the 
abilities of marine mammals to feed in the area where seismic work is 
planned. Some of the fish that do not avoid the approaching airguns 
(probably a small number) may be subject to auditory or other injuries.
    Zooplankton that are very close to the source may react to the 
airgun's impulse. These animals have an exoskeleton and no air sacs; 
therefore, little or no mortality is expected. Many crustaceans can 
make sounds and some crustacea and other invertebrates have some type 
of sound receptor. However, the reactions of zooplankton to sound are 
not known. Some mysticetes feed on concentrations of zooplankton. A 
reaction by zooplankton to a seismic impulse would only be relevant to 
whales if it caused a concentration of zooplankton to scatter. Pressure 
changes of sufficient magnitude to cause this type of reaction would 
probably occur only very close to the source, so few zooplankton 
concentrations would be affected. Impacts on zooplankton behavior are 
predicted to be negligible, and this would translate into negligible 
impacts on feeding mysticetes.

Potential Effects on Subsistence Use of Marine Mammals

    The proposed seismic project could potentially impact the 
availability of marine mammals for subsistence harvests in a very small 
area immediately around the Ewing, and for a very short time period 
while conducting seismic activities. However, considering the limited 
time and locations for the planned surveys, the proposed survey is not 
expected to have an unmitigable adverse impact on the availability of 
Steller sea lions, harbor seals or northern sea otters for subsistence 
harvests. Nevertheless, L-DEO plans to coordinate its activities with 
local subsistence communities so that seismic activities will be 
conducted outside subsistence hunting areas and times, if possible.

Mitigation

    For the subject seismic survey in the GOA, L-DEO will deploy 2 GI-
airguns as an energy source, with a total discharge volume of 210 
in\3\. The energy from the airguns will be directed mostly downward. 
The directional nature of the airguns to be used in this project is an 
important mitigating factor. This directionality will result in reduced 
sound levels at any given horizontal distance as compared with the 
levels expected at that distance if the source were omnidirectional 
with the stated nominal source level. Also, the small size of these 
airguns is an inherent and important mitigation measure that will 
reduce the potential for effects relative to those that might occur 
with large airgun arrays. This measure is in conformance with NMFS 
encouraging seismic operators to use the lowest intensity airguns 
practical to accomplish research objectives.

Safety Radii

    Received sound levels have been modeled by L-DEO for the 2 GI-
airguns, in relation to distance and direction from the airguns. The 
model does not allow for bottom interactions, and is most directly 
applicable to deep water. Based on the model, the distances from the 2 
G-airguns where sound levels of 190 dB, 180 dB, 170 dB, and 160 dB re 1 
microPa (rms) are predicted to be received are shown in the >1000 m 
(3281 ft) line of Table 1.
    Empirical data concerning these safety radii have been acquired 
based on measurements during the acoustic verification study conducted 
by L-DEO in the northern Gulf of Mexico from 27 May to 3 June 2003 (see 
68 FR 32460, May 30, 2003). Although the results are limited, L-DEO's 
analysis of the acoustic data from that study (Tolstoy et al., 2004) 
indicate that the radii around the airguns where the received level 
would be 180 dB re 1 microPa (rms), the safety zone applicable to 
cetaceans, vary with water depth.
    The proposed study area will occur in water approximately 30-3000 m 
(98-9843 ft) deep. In deep water (>1000 m (3281 ft)), the safety radii 
during airgun operations will be the values predicted by L-DEO's model 
(Table 1). Therefore, the assumed 180- and 190-dB radii are 54 m (177 
ft) and 17 m (56 ft), respectively. In intermediate water depths (100-
1000 m (328-3281 ft)), L-DEO has applied a 1.5x correction factor to 
the estimates provided by the model for deep water situations. The 
assumed 180- and 190-dB radii in intermediate-depth water are 81 m (266 
ft) and 26 m (85 ft), respectively. For operations in shallow (<100 m 
(328 ft)) water, L-DEO has applied conservative correction factors to 
the predicted radii for the 2 GI-airgun array. The 180- and 190-dB 
radii in shallow water are assumed to be 400 m (1312 ft) and 250 m (820 
ft), respectively. However, NMFS has some concerns regarding 
propagation in very shallow water and has determined that for water 
depths less than 100 m (328 ft), L-DEO will establish a safety zone for 
marine mammals and other endangered marine species at 170 dB. As 
indicated in Table 1, the 170-dB rms isopleth for shallow water will be 
750 m (2461 ft). The 2-GI airgun array will be immediately shutdown 
when cetaceans or pinnipeds are detected within or about to enter the 
appropriate 170-, 180-, or 190-dB zone.

Additional Mitigation Measures

    The following mitigation measures, as well as marine mammal visual 
monitoring (discussed later in this document), will be implemented for 
the subject seismic surveys: (1) Speed and course alteration (provided 
that they do not compromise operational safety requirements); (2) shut-
down and ramp-up procedures; (3) conducting inshore seismic from 
upstream and proceeding towards the sea whenever possible to avoid 
trapping marine mammals; (4)

[[Page 58150]]

scheduling seismic operations in inshore waters during daylight and 
coring operations during nighttime whenever possible; (5) a prohibition 
on conducting seismic operations in water depths less than 30 m (98 
ft); and (6) avoid encroaching upon critical habitat around Steller sea 
lion rookeries and haulouts. As discussed elsewhere in this document, 
special mitigation measures will be implemented for the North Pacific 
right whale.
    Although a ``power-down'' procedure is often applied by L-DEO 
during seismic surveys with larger arrays of airguns, NMFS is not 
requiring power down to a single gun during this project. Powering down 
from two guns to one gun would make only a small difference in the 180- 
or 190-dB zone, which is not enough distance to allow one-gun to 
continue operations if a mammal came within the safety zone for two 
guns.
    At night, vessel lights and/or night-vision devices (NVDs) could be 
useful in sighting some marine mammals at the surface within a short 
distance from the ship (within the safety radii for the 2-GI guns in 
deep and intermediate waters). Thus, start up of the airguns may be 
possible at night in deep and intermediate waters, in situations when 
the entire safety zone is visible with vessel lights and NVDs. However, 
due to the limitation on conducting nighttime seismic in shallow water, 
nighttime start ups of the airguns are not authorized.

Speed and Course Alteration

    If a marine mammal is detected outside the safety zone and, based 
on its position and the relative motion, is likely to enter the safety 
zone, the vessel's speed and/or direct course may, when practical and 
safe, be changed in a manner that also minimizes the effect to the 
planned science objectives. The marine mammal activities and movements 
relative to the seismic vessel will be closely monitored to ensure that 
the marine mammal does not approach within the safety zone. If the 
mammal appears likely to enter the safety zone, further mitigative 
actions will be taken (i.e., either further course alterations or shut 
down of the airguns). In the closely constrained waters of Lynn Canal, 
Muir Inlet, and Frederick Sound, it is unlikely that significant 
alterations to the vessel's speed or course could be made. In these 
circumstances, shut-down procedures would be implemented rather than 
speed or course changes.

Shut-down Procedures

    If a marine mammal is detected outside the safety zone but is 
likely to enter the safety zone, and if the vessel's speed and/or 
course cannot be changed to avoid having the mammal enter the safety 
zone, the airguns will be shut down before the mammal is within the 
safety zone. Likewise, if a mammal is already within the safety zone 
when first detected, the airguns will be shut down immediately. The 
airguns will be shut down if a North Pacific right whale is sighted 
from the vessel, even if it is located outside the safety zone.
    Following a shut down, airgun activity will not resume until the 
marine mammal has cleared the safety zone. The animal will be 
considered to have cleared the safety zone if it (1) is visually 
observed to have left the safety zone, or (2) has not been seen within 
the zone for 15 min in the case of small odontocetes and pinnipeds, or 
(3) has not been seen within the zone for 30 min in the case of 
mysticetes and large odontocetes, including sperm, pygmy sperm, dwarf 
sperm, and beaked whales.
    If the complete safety zone has not been visible for at least 30 
min prior to the start of operations in either daylight or nighttime 
(in offshore waters), airgun operations will not commence. However, if 
the airgun array has been operational before nightfall, it can remain 
operational throughout the night, even though the entire safety radius 
may not be visible. If the entire safety zone is visible at night, 
using vessel lights and NVDs (as may be the case in deep and 
intermediate waters), then start up of the airguns may occur at night.

Ramp-up

    When airgun operations commence after a certain period without 
airgun operations, the number of guns firing will be increased 
gradually, or ``ramped up'' (also described as a ``soft start''). 
Usually, operations begin with the smallest gun in the array and guns 
are added in sequence such that the source level of the array will 
increase in steps not exceeding 6 dB per 5-min period. However, during 
this survey, with only 2 GI-guns, ramp-up will be implemented by 
turning on one airgun, followed 5 minutes later by the second airgun. 
Throughout the ramp-up procedure, the safety zone will be maintained.

Other Mitigation

    Because this seismic survey is being conducted in inshore waters, 
NMFS has determined that the following mitigation measures are 
necessary to ensure that no marine mammals are injured and that 
takings, by Level B harassment, are at the lowest level practicable.
    1. L-DEO must conduct inshore seismic from upstream and proceeding 
towards the sea whenever possible to avoid trapping marine mammals. If 
mammals are averse to seismic sounds they may move upstream to avoid 
increasing SPLs. Although NMFS is also prohibiting takes in waters 
shallower than 30 m (98 ft) to limit sound propagation in very shallow 
water, this mitigation measure will ensure that these mammals have an 
opportunity to escape to deeper waters and not have a potential for 
stranding.
    2. L-DEO must limit seismic operations in inshore waters to 
daylight and coring operations to nighttime whenever possible. This was 
clarified in RTC 11.

Marine Mammal Monitoring

    L-DEO must have at least three visual observers on board the Ewing, 
and at least two must be experienced marine mammal observers that NMFS 
has approved in advance of the start of the GOA cruise. These observers 
will be on duty in shifts of no longer than 4 hours.
    The visual observers will monitor marine mammals and sea turtles 
near the seismic source vessel during all daytime operations and during 
any night-time airgun operations, although night-time seismic 
operations are unlikely to be conducted during this survey (see 
Mitigation). Vessel-based observers will watch for marine mammals and 
sea turtles near the seismic vessel during periods with shooting 
(including ramp-ups), and for 30 minutes prior to the planned start of 
airgun operations after a shut-down.
    Use of multiple observers will increase the likelihood that marine 
mammals near the source vessel are detected. L-DEO bridge personnel 
will also assist in detecting marine mammals and implementing 
mitigation requirements whenever possible (they will be given 
instruction on how to do so).
    The observer(s) will watch for marine mammals from the highest 
practical vantage point on the vessel, which is either the bridge or 
the flying bridge. On the bridge of the Ewing, the observer's eye level 
will be 11 m (36 ft) above sea level, allowing for good visibility 
within a 210 arc. If observers are stationed on the flying bridge, the 
eye level will be 14.4 m (47.2 ft) above sea level. The observer(s) 
will systematically scan the area around the vessel with Big Eyes 
binoculars, reticle binoculars (e.g., 7 X 50 Fujinon) and with the 
naked eye during the daytime. Laser range-finding binoculars (Leica 
L.F. 1200 laser rangefinder or equivalent) will be available to assist 
with distance

[[Page 58151]]

estimation. The observers will be used to determine when a marine 
mammal or sea turtle is in or near the safety radii so that the 
required mitigation measures, such as course alteration and shut-down, 
can be implemented. If the airguns are shut down, observers will 
maintain watch to determine when the animal is outside the safety 
radius.
    In addition to vessel monitoring during seismic operations, 
observers will also conduct monitoring after the seismic operation has 
been terminated for that line transect while the array is being pulled 
from the water and the vessel returns to the selected coring site. In 
most cases this will mean returning along the survey line. During that 
time, the observer will look for marine mammals that might have been 
injured as a result of seismic (although no injuries are expected to 
occur). Also, during coring operations in inshore waters, when that 
coring operation occurs during daylight hours (most coring should be 
conducted during night-time), the ship's captain may authorize the 
ship's small boat to look for marine mammals on or off the ship's 
previous track. Because there is a safety concern, the Ewing's captain 
has sole authority in this matter. For safety reasons, the boat must 
remain in visual or radio contact so it can safely return to the Ewing 
should weather conditions change or if the boat were disabled. At least 
one trained biological observer will be on this boat.

Passive Acoustic Monitoring (PAM)

    Although PAM has been used in previous seismic surveys, L-DEO will 
not use the PAM system during this research cruise. First, the safety 
radii are significantly smaller than those found for the larger L-DEO 
arrays, making the PAM unnecessary for locating marine mammals. 
Secondly, the effectiveness of the PAM in shallow water is not high and 
third, because of the coring operations, additional berthing is 
unavailable for the PAM operators. Making room available for the PAM 
acoustic technician would require the use of one less marine mammal 
observer. Again, because of the small safety zone, the recommendation 
that seismic work be conducted during daylight to the extent possible, 
and the limited effectiveness of the PAM in shallow water, NMFS has 
decided that the 3rd observer is more valuable for conducting small 
boat surveys and to assist in night-time monitoring than the use of the 
PAM.

Reporting

    L-DEO will submit a report to NMFS within 90 days after the end of 
the cruise, which is currently predicted to occur during August, 2004. 
The report will describe the operations that were conducted and the 
marine mammals that were detected. The report must provide full 
documentation of methods, results, and interpretation pertaining to all 
monitoring tasks. The report will summarize the dates and locations of 
seismic operations, marine mammal sightings (dates, times, locations, 
activities, associated seismic survey activities), and estimates of the 
amount and nature of potential take of marine mammals by harassment or 
in other ways.

Determinations

    NMFS has determined that the impact of conducting the seismic 
survey in the GOA in the northeastern Pacific Ocean will result, at 
worst, in a temporary modification in behavior by certain species of 
marine mammals. This activity is expected to result in no more than a 
negligible impact on the affected species or stocks. For reasons stated 
previously in this document, this determination is supported by (1) the 
likelihood that, given sufficient notice through slow ship speed and 
ramp-up, marine mammals are expected to move away from a noise source 
that it is annoying prior to its becoming potentially injurious; (2) 
recent research that indicates that TTS is unlikely (at least in 
delphinids) until levels closer to 200-205 dB re 1 microPa are reached 
rather than 180 dB re 1 microPa; (3) the fact that 200-205 dB isopleths 
would be within 100 m (328 ft) of the vessel even in shallow water; and 
(4) the likelihood that marine mammal detection ability by trained 
observers is close to 100 percent during daytime and remains high at 
night to that distance from the seismic vessel. As a result, no take by 
injury and/or death is anticipated, and the potential for temporary or 
permanent hearing impairment is very low and will be avoided through 
the incorporation of the required mitigation measures discussed in this 
document.
    While the number of potential incidental harassment takes will 
depend on the distribution and abundance of marine mammals in the 
vicinity of the survey activity, the number of potential harassment 
takings is estimated to be small. In addition, the proposed seismic 
program will not have an unmitigable adverse impact on any subsistence 
hunts, since seismic operations will not take place in major 
subsistence whaling and sealing areas and may have only minor Level B 
harassment impacts on Steller sea lions and harbor seals that might be 
used for subsistence.

Endangered Species Act (ESA)

    NMFS has issued a biological opinion regarding the effects of this 
action on ESA-listed species and critical habitat under the 
jurisdiction of NMFS. That biological opinion concluded that this 
action is not likely to jeopardize the continued existence of listed 
species or result in the destruction or adverse modification of 
critical habitat. A copy of the Biological Opinion is available upon 
request (see ADDRESSES). However, sea otters are under the jurisdiction 
of the U.S. Fish and Wildlife Service (USFWS). L-DEO contacted the 
USFWS regarding this species. The USFWS determined that sea otters 
would not be affected by the 2 GI-airgun array being employed in the 
GOA project.

National Environmental Policy Act (NEPA)

    The NSF made a FONSI determination on April 7, 2004, based on 
information contained within its EA, that implementation of the subject 
action is not a major Federal action having significant effects on the 
environment within the meaning of NEPA. NSF determined, therefore, that 
an environmental impact statement would not be prepared. On June 23, 
2004 (69 FR 34996), NMFS noted that the NSF had prepared an EA for the 
GOA surveys and made this EA was available upon request. 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 NSF's EA and determined 
that the NSF EA accurately and completely describes the proposed action 
alternative, 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 the 
NSF EA under 40 CFR 1506.3 and made it's own FONSI. The NMFS FONSI also 
takes into consideration additional mitigation measures required by the 
IHA that are not in NSF's EA. Therefore, it is not necessary to issue a 
new EA, supplemental EA or an environmental impact statement for the 
issuance of an IHA to L-DEO for this activity. A copy of the NSF EA and 
the NMFS FONSI for this activity is available upon request (see 
ADDRESSES).

Authorization

    NMFS has issued an IHA to L-DEO to take marine mammals, by 
harassment, incidental to conducting seismic

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surveys in the Gulf of Alaska for a 1-year period, provided the 
mitigation, monitoring, and reporting requirements are undertaken.

    Dated: September 22, 2004.
Laurie K. Allen,
Director, Office of Protected Resources, National Marine Fisheries 
Service.
[FR Doc. 04-21847 Filed 9-28-04; 8:45 am]
BILLING CODE 3510-22-S