Small Takes of Marine Mammals Incidental to Specified Activities; Low-Energy Seismic Surveys in the South Pacific Ocean, 56955-56965 [06-8353]

Agencies

• DEPARTMENT OF COMMERCE
• National Oceanic and Atmospheric Administration

[Federal Register Volume 71, Number 188 (Thursday, September 28, 2006)]
[Notices]
[Pages 56955-56965]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 06-8353]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

[I.D. 083106B]


Small Takes of Marine Mammals Incidental to Specified Activities; 
Low-Energy Seismic Surveys in the South Pacific Ocean

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

ACTION: Notice of receipt of application and proposed incidental take 
authorization; request for comments.

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SUMMARY: NMFS has received an application from the Scripps Institution 
of Oceanography (SIO), a part of the University of California, for an 
Incidental Harassment Authorization (IHA) to take small numbers of 
marine mammals, by harassment, incidental to conducting an 
oceanographic survey in the South Pacific Ocean (SPO). Under the Marine 
Mammal Protection Act (MMPA), NMFS is requesting comments on its 
proposal to issue an authorization to SIO to incidentally take, by 
harassment, small numbers of several species of cetaceans for a limited 
period of time in December 2006, and January 2007.

DATES: Comments and information must be received no later than October 
30, 2006.

ADDRESSES: Comments on the application should be addressed to: Michael 
Payne, Chief, Permits, Conservation and Education Division, Office of 
Protected Resources, National Marine Fisheries Service, 1315 East-West 
Highway, Silver Spring, MD 20910-3225, or by telephoning the contact 
listed here. The mailbox address for providing email comments is 
PR1.083106B @noaa.gov. Comments sent via e-mail, including all 
attachments, must not exceed a 10-megabyte file size. A copy of the 
application (containing a list of the references used in this document) 
may be obtained by writing to this address or by telephoning the 
contact listed here and are also available at:https://www.nmfs.noaa.gov/
pr/permits/incidental.htm#iha.

FOR FURTHER INFORMATION CONTACT: Kenneth Hollingshead, Office of 
Protected Resources, NMFS, (301) 713-2289, ext 128.

SUPPLEMENTARY INFORMATION:

[[Page 56956]]

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.
    Authorization shall be granted if NMFS finds that the taking will 
have a negligible impact on the species or stock(s), will not have an 
unmitigable adverse impact on the availability of the species or 
stock(s) for subsistence uses, and that the permissible methods of 
taking and requirements pertaining to the mitigation, 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 with respect to certain 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 July 24, 2006, NMFS received an application from SIO for the 
taking, by harassment, of several species of marine mammals (see Marine 
Mammals Affected by this Activity later in this document) incidental to 
conducting a low-energy marine seismic survey program during December 
2006 and January 2007 in the SPO. SIO plans to conduct a seismic survey 
at several sites in the SPO (as illustrated in Figure 1 in SIO's 
application) as part of the Integrated Ocean Drilling Program (IODP).
    The purpose of the research program is to conduct a piston/ gravity 
coring, magnetic, and seismic survey program at 12 sites in the SPO. 
The results will be used to (1) document the metabolic activities, 
genetic composition, and biomass of prokaryotic (principally 
unicellular organisms without a cell nucleus) communities in the 
subseafloor sediments with very low total activity; (2) quantify the 
extent to which those communities may be supplied with harvestable 
energy by water radiolysis, a process independent of the surface 
photosynthetic world; and (3) survey broad characteristics of 
subseafloor communities and habitats in this region, in order to refine 
the planning and objectives of a specific IODP drilling proposal.
    Included in the research planned for 2006 is the use of multi-beam 
and Chirp techniques to map the seafloor, and high-resolution seismic 
methods to image the subsea floor. The seismic survey is required to 
locate optimal piston/gravity- coring sites.
    The seismic surveys will involve one vessel. The source vessel, the 
R/V Roger Revelle, will deploy a pair of low-energy Generator-Injector 
(GI) airguns as an energy source (each with a discharge volume of 45 
in\3\), plus a 800-m (1476-ft) long, 48-channel, towed hydrophone 
streamer. As the airguns are towed along the survey lines, the 
receiving system will receive the returning acoustic signals.
    The Revelle is scheduled to depart from Apia, Samoa, on or about 
December 7, 2006, and to arrive at Dunedin, New Zealand, on or about 
January 17, 2007. The program will consist of approximately 1930 km 
(1042 nm) of surveys, including turns. Water depths within the seismic 
survey areas are 3200-5700 m (10499-18701 ft). The surveys will be 
conducted entirely in international waters. The GI guns will be 
operated on a small grid for about 6-10 hours at each of 12 sites 
during approximately December 10, 2006, to January 13, 2007. There will 
be additional seismic operations associated with equipment testing, 
start-up, and repeat coverage of any areas where initial data quality 
is sub-standard.
    All planned geophysical data acquisition activities will be 
conducted by SIO scientists who have proposed the study. The vessel 
will be self-contained, and the crew will live aboard the vessel for 
the entire cruise.
    In addition to the operations of the GI guns, a 3.5-kHz sub-bottom 
profiler, passive geophysical sensors to conduct magnetic surveys, and 
a Kongsberg-Simrad EM-120 multi-beam sonar will be used continuously 
throughout the cruise.
    The energy to the airguns is compressed air supplied by compressors 
on board the source vessel. Seismic pulses will be emitted at intervals 
of 6-10 seconds (sec.). At a speed of 5-8 knots (9.3-14.8 km/h), the 6-
10 sec. spacing corresponds to a shot interval of approximately 15.5-41 
m (51-135 ft).
    The generator chamber of each GI gun, the one responsible for 
introducing the sound pulse into the ocean, is 45 in\3\. The larger 
(105 in\3\) injector chamber injects air into the previously-generated 
bubble to maintain its shape, and does not introduce more sound into 
the water. The two 45/105 in\3\ GI guns will be towed 8 m (26.2 ft) 
apart side by side, 21 m (68.9 ft) behind the Revelle, at a depth of 2 
m (6.6 ft).

General-Injector Airguns

    The Revelle's 2 GI-airguns will be used during this proposed 
program. These GI-airguns have a zero to peak (peak) source output of 
230.7 dB re 1 microPascal-m (3.4 bar-m) and a peak-to-peak (pk-pk) 
level of 235.9B (6.2 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 
airgun 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 and actual levels experienced by any organism more 
than 1 m (3.3 ft) from any GI gun will be significantly lower. In this 
case, that will be about 224.6 dB re 1 microPa-m peak, or 229.8 dB re 1 
microPa-m peak-to-peak (pk-pk).
    Further, the root mean square (rms) received levels that are used 
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 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 dB rms in the 
far field would typically correspond to a

[[Page 56957]]

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 2.0 m (6.6 ft), where the ambient pressure is 
approximately 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 is provided in SIO 
application and in previous Federal Register documents (see 69 FR 31792 
(June 7, 2004) or 69 FR 34996 (June 23, 2004)).
    Received sound levels have been modeled by Lamont-Doherty Earth 
Observatory (L-DEO) for a number of airgun configurations, including 
two 45-in\3\ Nucleus G-guns, in relation to distance and direction from 
the airguns. The L-DEO model does not allow for bottom interactions, 
and is therefore most directly applicable to deep water. Based on the 
modeling, estimates of the maximum distances from the GI guns where 
sound levels of 190, 180, and 160 dB microPascal-m (rms) are predicted 
to be received are shown in Table 1. Because the model results are for 
the G guns, which have more energy than GI guns of the same size, those 
distances are overestimates of the distances for the 45 in\3\ GI guns.

 Table 1. Distances to which sound levels 190, 180, and 160 dB re 1 microPa (rms) might be received from two 45-
 in G guns, similar to the two 45-in\3\ GI guns that will be used during the seismic survey in the South Pacific
     Ocean during December, 2006 and January, 2007. Distances are based on model results provided by L-DEO.
 
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                                                        Estimated Distances at Received Levels(m)
                                        ------------------------------------------------------------------------
Water depth                              190 dB.............  180 dB............                         160 dB
                                        ------------------------------------------------------------------------
>1000m                                   10.................  40................                            400
----------------------------------------------------------------------------------------------------------------

    Empirical data concerning the 180- and 160- dB distances have been 
acquired based on measurements during the acoustic verification study 
conducted by L-DEO in the northern Gulf of Mexico from May 27 to June 
3, 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), the safety criterion applicable to 
cetaceans (NMFS, 2000), varies with water depth. Similar depth-related 
variation is likely in the 190-dB distances applicable to pinnipeds. 
Correction factors were developed for water depths 100 - 1000 m (328 - 
3281 ft) and less than 100 m. As the proposed SIO survey will occur in 
water depths of 3200-5700 m (10499-18701 ft), correction factors are 
not relevant here.
    The empirical data indicate that, for deep water (greater than 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, SIO 
proposes that the safety radii during airgun operations in deep water 
will be the values predicted by L-DEO's model (Table 1). Therefore, the 
assumed 180- and 190-dB radii are 40 m (131 ft) and 10 m (33 ft), 
respectively.
    Bathymetric Sonar and Sub-bottom Profiler
    A description of the Kongsberg-Simrad EM120 multi-beam sonar and 
the sub-bottom profiler onboard the Revelle can be reviewed in the SIO 
application. These descriptions have also been provided previously (see 
71 FR 6041, February 6, 2006 and 71 FR 14839, March 24, 2006) and do 
not need to be repeated here.

Characteristics of Airgun Pulses

    Discussion of the characteristics of airgun pulses was provided in 
several previous Federal Register documents (see 69 FR 31792 (June 7, 
2004) or 69 FR 34996 (June 23, 2004)) and is not repeated here. 
Reviewers are encouraged to read these earlier documents for additional 
information.

Marine Mammals Affected by the Activity

    Forty species of cetacean, including 31 odontocete (dolphins and 
small- and large-toothed whales) species and nine mysticete (baleen 
whales) species, are believed by scientists to occur in the SPO in the 
proposed seismic survey area. Detailed information on these species is 
contained in the SIO application and the National Science Foundation 
(NSF) EA which are available at: https://www.nmfs.noaa.gov/pr/permits/
incidental.htm#iha. Table 2 in both the SIO application and NSF EA 
summarizes the habitat, occurrence, and regional population estimate 
for these species. The following cetacean species may be affected by 
this low-intensity seismic survey: Sperm whale, pygmy and dwarf sperm 
whales, southern bottlenose whale, Arnoux's beaked whale, Cuvier's 
beaked whale, Shepherd's beaked whale, mesoplodont beaked whales 
(Andrew's beaked whale, Blainville's beaked whale, gingko-toothed 
whale, Gray's beaked whale, Hector's beaked whale, spade-toothed whale, 
strap-toothed whale), melon-headed whale, pygmy killer whale, false 
killer whale, killer whale, long-finned pilot whale, short-finned pilot 
whale, rough-toothed dolphin, bottlenose dolphin, pantropical spotted 
dolphin, spinner dolphin, striped dolphin, short-beaked common dolphin, 
hourglass dolphin, Fraser's dolphin , Risso's dolphin, southern right 
whale dolphin, spectacled porpoise, humpback whale, southern right 
whale, pygmy right whale, common minke whale, Antarctic minke whale, 
Bryde's whale, sei whale, fin whale and blue whale.
    Five species of pinnipeds could potentially occur in the proposed 
seismic survey area: southern elephant seal, leopard seal, crabeater 
seal, Antarctic fur seal, and the sub-Antarctic fur seal. All are 
likely to be rare, if they occur at all, as their normal distributions 
are south of the SIO survey area. Outside the breeding season, however, 
they disperse widely in the open ocean (Boyd, 2002; King, 1982;

[[Page 56958]]

Rogers, 2002). Only three species of pinniped are known to wander 
regularly into the SIO survey area: the Antarctic fur seal, the sub-
Antarctic fur seal, and the leopard seal (Reeves et al., 1999). Leopard 
seals are seen as far north as the Cook Islands (Rogers, 2002).

Potential Effects on Marine Mammals

    As outlined in 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 SIO application and two previous SIO IHA notices (71 FR 6041, 
February 6, 2006, and 71 FR 14839, March 24, 2006) provide information 
on what is known about the effects on marine mammals of the types of 
seismic operations planned by SIO. The types of effects considered in 
these documents are (1) tolerance, (2) masking of natural sounds, (2) 
behavioral disturbance, (3) potential hearing impairment, and (4) other 
non-auditory physical effects. This information is incorporated herein. 
Please refer to these documents for information and analyses on 
potential impacts to marine mammals by seismic activities.
    Summarizing from these analyses, given the relatively small size of 
the airguns planned for the present project, SIO and NMFS believe it is 
very unlikely that there would be any cases of temporary or permanent 
hearing impairment, or non-auditory physical effects. Also, behavioral 
disturbance is expected to be limited to distances less than 400 m 
(1312 ft) from the seismic source. This is the zone calculated for 160 
dB or the onset of Level B (behavioral) harassment. As a result, 
acoustic effects are anticipated to be considerably less than would be 
the case with a large array of airguns.

Possible Effects of Mid-frequency Sonar Signals

    A multi-beam bathymetric sonar and a sub-bottom profiler will be 
operated from the source vessel essentially continuously during much of 
the planned survey. Details about these sonars and potential effects on 
marine mammals (masking, behavioral response, hearing impairment and 
other physical effects) have been provided in the SIO application and 
by NMFS previously (see 71 FR 6041, February 6, 2006, and 71 FR 14839, 
March 24, 2006) and are not repeated here. This information is 
incorporated herein by citation. Please refer to these documents for 
information and analyses on potential impacts to marine mammals by 
these mid-frequency sonar activities.

Estimates of Take by Harassment for the SPO Seismic Survey

    Although information contained in several documents cited and 
summarized in SIO's application 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). Given the small zone of impact due to the low-energy 
seismic sources and the proposed mitigation and monitoring for this 
survey (see Mitigation and Monitoring later in this document), all 
anticipated effects involve, at most, a temporary change in behavior 
that may constitute Level B (behavioral) harassment, and no injury or 
mortality is likely. The proposed mitigation measures will essentially 
eliminate the possibility of Level A harassment or mortality. As 
described later, SIO has calculated the ``best estimates'' for the 
numbers of animals that could be taken by Level B harassment during the 
proposed SPO seismic survey using data on marine mammal density 
(numbers per unit area) and estimates of the size of the affected area, 
as shown in the predicted RMS radii table (see Table 1).
    The Level B harassment estimates are based on a consideration of 
the number of marine mammals that might be exposed to sound levels at 
or higher 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 zones of influence of the multi-beam 
sonar and sub-bottom profiler are less than that for the airguns, so it 
is assumed that during simultaneous operations of these instruments 
that any marine mammals close enough to be affected by the multi-beam 
and sub-bottom profiler sonars 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. Also, given 
their characteristics (described in SIO's application and analyzed by 
NMFS in previous SIO authorizations), no Level B harassment takings are 
considered likely when the multibeam and sub-bottom profiler are 
operating but the airguns are silent.
    SIO notes that it is difficult to make accurate, scientifically 
defensible, and

[[Page 56959]]

observationally verifiable estimates of the number of individuals 
likely to be subject to low-level harassment by the noise from SIO's GI 
guns. There are many uncertainties in marine mammal distribution and 
seasonally varying abundance, and in local horizontal and vertical 
distribution; in marine mammal reactions to varying frequencies and 
levels of acoustic pulses; and in perceived sound levels at different 
horizontal and oblique ranges from the source.
    The best estimate of the potential number of exposures to received 
levels equal to, or greater than, 160 dB re 1 microPa (rms) was 
calculated by SIO by multiplying the expected density of the species/
stock; times the anticipated total line-kilometers of operations with 
the 2 GI guns (including turns and additional buffer line km to allow 
for repeating of lines due to equipment malfunction, bad weather, 
etc.), times the cross-track distances within which received sound 
levels are predicted to be 160 dB or greater.
    For the 2 GI guns, that cross track distance is 2x the predicted 
160-dB radii of 400 m (1312 ft) in water depths greater than 1000 m 
(3281 ft). Based on that method, SIO obtained the ``best'' and 
``maximum'' estimates of the number of marine mammal exposures to 
airgun sounds 160 dB re 1 microPa (rms) and higher for each of the 
ecological provinces using the reported average and maximum densities 
from Tables 3 and 4 in SIO's application. The two estimates were then 
added to give total estimated exposures. The estimates show that very 
small numbers of the five endangered large whale species may be exposed 
to such noise levels (Table 5). SIO's best estimates for these species 
are one exposure each for the sperm whale, southern right whale, sei 
whale, and fin whale. The vast majority of the best estimate for 
exposures to seismic sounds 160 dB and higher would involve delphinids. 
Best estimates of the number of exposures of cetaceans, in descending 
order, are bottlenose dolphin (292 exposures), rough-toothed and 
spotted dolphin (80 exposures each), and southern right whale dolphin 
(73 exposures). SIO believes that based on the empirical calibration 
data collected in the Gulf of Mexico for 2 GI guns in deep water, 
actual 160-dB distances in deep water are likely to be less than 
predicted (Tolstoy et al., 2004) and, therefore, the predicted numbers 
of marine mammals that might be exposed to sounds 160 dB or greater may 
be somewhat overestimated.
    While data regarding distribution, seasonal abundance, and response 
of pinnipeds to seismic sonar is sparse, NMFS believes the Revelle is 
unlikely to encounter any of the four pinniped species that live, for 
at least part of the year, in SIO's proposed survey area because of the 
decreased likelihood of encountering them in the very deep water, the 
relatively small area proposed to be ensonified, and the likely 
effectiveness of the required mitigation measures in such a small area.
    Table 2 provides the best estimate of the numbers of each species 
that could be exposed to seismic sounds equal to, or greater than, 160 
dB and the number of marine mammals requested to be taken by Level B 
harassment. A detailed description on the methodology used by SIO to 
arrive at the estimates of Level B harassment takes that are provided 
in Table 2 can be found in SIO's application for the SPO survey.
BILLING CODE 3510-22-S

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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, particularly when feeding 
whales are involved. Few mysticetes are expected to be encountered 
during the proposed survey in the SPO (Table 2) and disturbance effects 
would be confined to shorter distances given the low-energy acoustic 
source to be used during this project. In addition, the estimated 
numbers presented in Table 2 are considered overestimates of actual 
numbers that may be harassed.
    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-gun array 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

[[Page 56962]]

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 of 160 dB re 1 
microPa (rms) or greater represent from 0 to approximately 0.07 percent 
of the regional SPO species populations (Table 2). In the case of 
endangered balaenopterids, it is likely that no more than 1 humpback, 
sei, or fin whale will be exposed to seismic sounds 160 dB re 1 microPa 
(rms) or greater, based on estimated densities of those species in the 
survey region. Therefore, SIO has requested an authorization to expose 
up to 1 individuals of each of these species to seismic sounds of 160 
dB or greater during the proposed survey given the possibility of 
encountering one or more groups. Best estimates of blue whales are that 
no individuals would be potentially exposed to seismic pulses with 
received levels 160 dB re 1 microPa (rms) or greater (Table 2).
    Higher numbers of delphinids may be affected by the proposed 
seismic surveys, but the population sizes of species likely to occur in 
the survey area are large, and the numbers potentially affected are 
small relative to population sizes (Table 2). As a result, NMFS 
believes that the seismic survey proposed by SIO will result in only 
small numbers of cetaceans being harassed incidental to conducting that 
activity.
    Mitigation measures such as controlled speed, course alteration, 
observers, ramp ups, and shut downs when marine mammals are seen within 
defined ranges should further reduce short-term reactions, and minimize 
any effects on hearing. In all cases, the effects are expected to be 
short-term, with no lasting adverse biological consequence. In light of 
the type of effects expected and the small percentages of affected 
stocks of cetaceans, the action is expected to have no more than a 
negligible impact on the affected species or stocks of cetaceans.

Effects on Pinnipeds

    Five pinniped species may be encountered at the survey sites, but 
their distribution and numbers have not been documented in the proposed 
survey area. In all likelihood, these species will be in southern 
feeding areas during the period for this survey. However, to ensure 
that the SIO project remains in compliance with the MMPA in the event 
that a few pinnipeds are encountered, SIO has requested an 
authorization to expose up to 3-5 individuals of each of the five 
pinniped species to seismic sounds with rms levels 160 dB re 1 microPa 
or greater. Therefore, the proposed survey would have, at most, a 
short-term effect on their behavior and no long-term impacts on 
individual pinnipeds or their populations. Responses of pinnipeds to 
acoustic disturbance are variable, but usually quite limited. Effects 
are expected to be limited to short-term and localized behavioral 
changes falling within the MMPA definition of Level B harassment. As is 
the case for cetaceans, the short-term exposures to sounds from the two 
GI-guns are not expected to result in any long-term consequences for 
the individuals or their populations and the activity is expected to 
have no more than a negligible impact on the affected species or stocks 
of pinnipeds.

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.
    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 at 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 injury-zone are likely to be displaced from this region 
prior to the approach of the airguns through avoidance reactions to the 
approaching 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 
microPa (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. 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 shock wave. 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

    There is no known legal subsistence hunting for marine mammals in 
the SPO, so the proposed SIO activities will not have any impact on the 
availability of these species or stocks for subsistence users.

Proposed Mitigation

    For the proposed seismic survey in the SPO, SIO will deploy 2 GI-
airguns as an energy source, each with a discharge volume of 45 in\3\. 
The energy from the airguns is 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

[[Page 56963]]

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 policy of 
encouraging seismic operators to use the lowest intensity airguns 
practical to accomplish research objectives.
    The following mitigation measures, as well as marine mammal visual 
monitoring (discussed later in this document), would be implemented for 
the subject seismic surveys if the Secretary issues an IHA: (1) Speed 
and course alteration (provided that they do not compromise operational 
safety requirements); (2)shut-down procedures; and (3) ramp-up 
procedures.

Speed and Course Alteration

    If a marine mammal is detected outside its respective safety zone 
(180 dB for cetaceans, 190 dB for pinnipeds) and, based on its position 
and the relative motion, is likely to enter the safety zone, the 
vessel's speed and/or direct course will, when practical and safe, be 
changed to avoid the mammal 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 marine 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).

Shut-down Procedures

    Although power-down procedures are often standard operating 
practice for seismic surveys, power-down is not proposed to be used for 
this activity because powering down from two guns to one gun would make 
only a small difference in the 180- or 190-dB radius--probably not 
enough to allow continued one-gun operations if a marine mammal came 
within the safety radius for two guns.
    If a marine mammal is detected outside the safety radius but is 
likely to enter the safety radius, and if the vessel's speed and/or 
course cannot be changed to avoid having the mammal enter the safety 
radius, the GI-guns will be shut down before the mammal is within the 
safety radius. Likewise, if a mammal is already within the safety zone 
when first detected, the airguns will be shut down immediately.
    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, beaked and bottlenose whales.
    During airgun operations following a shut-down whose duration has 
exceeded these specified limits, the airgun array will be ramped-up 
gradually.

Ramp-up Procedure

    A ramp-up procedure will be followed when the airguns begin 
operating after a period without airgun operations. The two GI guns 
will be added in sequence 5 minutes apart. During ramp-up procedures, 
the safety radius for the two GI guns will be maintained.
    During the day, ramp-up cannot begin from a shut-down unless the 
entire 180-dB safety radius has been visible for at least 30 minutes 
prior to the ramp up (i.e., no ramp-up can begin in heavy fog or high 
sea states).
    During nighttime operations, if the entire safety radius is visible 
using vessel lights and night-vision devices (NVDs) (as may be the case 
in deep and intermediate waters), then start up of the airguns from a 
shut down may occur, after completion of the 30-minute observation 
period.
    Comments on past IHAs raised the issue of prohibiting nighttime 
operations as a practical mitigation measure. However, this is not 
practicable due to cost considerations and ship time schedules. If the 
Revelle was prohibited from operating during nighttime, each trip could 
require an additional several days to complete.
    If a seismic survey vessel is limited to daylight seismic 
operations, efficiency would also be much reduced. For seismic 
operations in general, a daylight-only requirement would be expected to 
result in one or more of the following outcomes: cancellation of 
potentially valuable seismic surveys; reduction in the total number of 
seismic cruises annually due to longer cruise durations; a need for 
additional vessels to conduct the seismic operations; or work conducted 
by non-U.S. operators or non-U.S. vessels when in waters not subject to 
U.S. law.

Marine Mammal Monitoring

    SIO must have at least three visual observers on board the Revelle, 
and at least two must be an experienced marine mammal observer that 
NMFS has approved in advance of the start of the SPO 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 airgun operations, 
during any nighttime start-ups of the airguns, and at night whenever 
daytime monitoring resulted in one or more shut-down situations due to 
marine mammal presence. During daylight, 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. Revelle 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), especially during ongoing operations at 
night when the designated observers are on stand-by and not required to 
be on watch at all times.
    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. 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 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 power-down or shut-down, can be implemented. If 
the GI-airguns are shut down, observers will maintain watch to 
determine when the animal is outside the safety radius.
    Observers will not be on duty during ongoing seismic operations at 
night; bridge personnel will watch for marine mammals during this time 
and will call for the airguns to be powered-down or shut-down if marine 
mammals are observed in or about to enter the safety radii. However, a 
biological observer must be on standby at night and available to assist 
the bridge watch if

[[Page 56964]]

marine mammals are detected at any distance from the Revelle. If the 2 
GI-airgun is ramped-up at night (see previous section), two marine 
mammal observers will monitor for marine mammals for 30 minutes prior 
to ramp-up and during the ramp-up using either deck lighting or NVDs 
that will be available (ITT F500 Series Generation 3 binocular image 
intensifier or equivalent).

Post-Survey Monitoring

    In addition, the biological observers will be able to conduct 
monitoring of most recently-run transect lines as the Revelle returns 
along parallel and perpendicular transect tracks (see inset of Figure 1 
in the SIO application). This will provide the biological observers 
with opportunities to look for injured or dead marine mammals (although 
no injuries or mortalities are expected during this research cruise).

Passive Acoustic Monitoring (PAM)

    Because of the very small zone for potential Level A harassment, 
SIO has not proposed to use the PAM system during this cruise.

Summary

    Taking into consideration the additional costs of prohibiting 
nighttime operations and the likely impact of the activity (including 
all mitigation and monitoring), NMFS has preliminarily determined that 
the proposed mitigation and monitoring ensures that the activity will 
have the least practicable impact on the affected species or stocks. 
Marine mammals will have sufficient notice of a vessel approaching with 
operating seismic airguns, thereby giving them an opportunity to avoid 
the approaching array; if ramp-up is required, two marine mammal 
observers will be required to monitor the safety radii using shipboard 
lighting or NVDs for at least 30 minutes before ramp-up begins and 
verify that no marine mammals are in or approaching the safety radii; 
ramp-up may not begin unless the entire safety radii are visible.

Reporting

    SIO will submit a report to NMFS within 90 days after the end of 
the cruise, which is currently predicted to occur during December, 2006 
and January, 2007. 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.
    During the recent SIO cruise to the Louisville Ridge (71 FR 6041, 
February 6, 2006), there were 5 sightings of marine mammals. All 
observed marine mammals were non-evasive of the research vessel and its 
activities. Only one sighting occurred while the seismic source was 
active. The animal's closest approach to the ship was greater than 2 km 
(1.08 nm), well outside the 40 m (131.2 ft) safety radius for the 
seismic source used on that cruise. For additional information please 
see the Louisville Ridge cruise report (https://www.nmfs.noaa.gov/pr/
permits/incidental.htm#iha.

Endangered Species Act (ESA)

    Under section 7 of the ESA, the National Science Foundation (NSF), 
the agency funding this SIO project, has begun consultation on the 
proposed seismic survey. NMFS will also consult on the issuance of an 
IHA under section 101(a)(5)(D) of the MMPA for this activity. 
Consultation will be concluded prior to a determination on the issuance 
of an IHA.

National Environmental Policy Act (NEPA)

    The NSF made a Finding of No Significant Impact (FONSI) 
determination on November 3, 2005 (70 FR 68102, November 9, 2005), 
based on information contained within its EA (see 70 FR 39346, July 7, 
2005, for public availability), that implement-ation of a low-energy 
seismic survey in the SPO is not a major Federal action having 
significant effects on the environment within the meaning of NEPA. The 
NSF determined, therefore, that an environmental impact statement would 
not be prepared.
    NMFS noted that the NSF had prepared an EA for a previous SIO 2-GI 
airgun survey in the SPO and made this EA available upon request (70 FR 
60287, October 17, 2005). In accordance with NOAA Administrative Order 
216-6 (Environmental Review Procedures for Implementing the National 
Environmental Policy Act, May 20, 1999), NMFS 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 its own FONSI. The NMFS FONSI also took into consideration 
additional mitigation measures that are not in NSF's EA. Therefore, 
because the actions described in that EA are similar in context and 
intensity to the current proposed activity, it is not necessary for 
NMFS to issue a new EA, a supplemental EA or an environmental impact 
statement for the proposed issuance of an IHA to SIO for this activity. 
A copy of the EA and previous FONSI for this activity is available upon 
request. A copy of the NSF EA for this activity is available upon 
request (see ADDRESSES).

Preliminary Conclusions

    NMFS has preliminarily determined that the impact of conducting the 
seismic survey in the SPO may result, at worst, in a temporary 
modification in behavior of small numbers of 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 preliminary 
determination is supported by: (1) the likelihood that, given advance 
notice through relatively slow ship speed and ramp-up, marine mammals 
are expected to move away from a noise source that is annoying before 
it becomes 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 well within 100 m (328 
ft) of the vessel even in shallow water; and (4) the likelihood that 
marine mammal detection in the safety zone by trained observers is 
close to 100 percent during daytime and remains high at night to the 
short distance from the seismic vessel. As a result, no take by injury 
or death is anticipated or authorized, and the potential for temporary 
or permanent hearing impairment is very low and would be avoided 
through the incorporation of the proposed mitigation measures mentioned 
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 interfere with any known legal subsistence hunts, 
since seismic operations will not take place in subsistence whaling and 
sealing areas

[[Page 56965]]

and will not affect marine mammals used for subsistence purposes.

Proposed Authorization

    NMFS proposes to issue an IHA to SIO for conducting an 
oceanographic seismic survey in the SPO, provided the previously 
mentioned mitigation, monitoring, and reporting requirements are 
incorporated. NMFS has preliminarily determined that the proposed 
activity would result in the harassment of small numbers of marine 
mammals; would have no more than a negligible impact on the affected 
marine mammal stocks; and would not have an unmitigable adverse impact 
on the availability of species or stocks for subsistence uses.

    Dated: September 22, 2006.
James H. Lecky,
Director, Office of Protected Resources, National Marine Fisheries 
Service.
[FR Doc. 06-8353 Filed 9-27-06; 8:45 am]
BILLING CODE 3510-22-C