Small Takes of Marine Mammals Incidental to Specified Activities; Low-Energy Seismic Surveys in the South Pacific Ocean, 75946-75952 [E6-21611]

Agencies

• DEPARTMENT OF COMMERCE
• National Oceanic and Atmospheric Administration

[Federal Register Volume 71, Number 243 (Tuesday, December 19, 2006)]
[Notices]
[Pages 75946-75952]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: E6-21611]


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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 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 an oceanographic survey in the 
South Pacific Ocean (SPO) has been issued to the Scripps Institution of 
Oceanography (SIO).

DATES: Effective from December 12, 2006, through December 11, 2007.

ADDRESSES:  The authorization and 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. The application is 
also available at: https://www.nmfs.noaa.gov/pr/permits/incidental.htm.

FOR FURTHER INFORMATION CONTACT: Kenneth Hollingshead, Office of 
Protected Resources, NMFS, (301) 713-2289, 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.
    An 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 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. 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. 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.
    A description of the Revelle's oceanographic research program is 
contained in SIO's application (see ADDRESSES for availability) and in 
NMFS' notice of receipt of SIO's IHA application (see 71 FR 56955 
(September 28, 2006)) and is not repeated here. There have been no 
significant changes in SIO's oceanographic research program between the 
September 28, 2006 Federal Register notice and NMFS' decision to issue 
the IHA

Comments and Responses

    A notice of receipt and request for 30-day public comment on the 
application and proposed authorization was published on September 28, 
2006 (71 FR 56955). During the 30-day public comment period, NMFS 
received comments only from the Marine Mammal Commission (Commission).
    Comment 1: The Commission recommends that NMFS issue the

[[Page 75947]]

requested authorization, provided the applicant is required to conduct 
all practicable monitoring and mitigation measures that reasonably can 
be expected to protect the potentially affected marine mammal species 
from serious injury. In that regard, the Commission notes that it 
submitted similar comments on this concern in letters dated December 
18, 2005 and February 21, 2006 on SIO's activities in the southwestern 
Pacific Ocean (SWPO) and eastern tropical Pacific (ETP). As in those 
cases, since several species of beaked whales occur in the proposed 
survey area, and given the uncertainties concern the effects of sound 
on these and possibly other species, caution is warranted.
    Response: NMFS responded to similar concerns from the Commission on 
January 30, 2006 (71 FR 3260), for SIO's ETP seismic survey and on 
February 6, 2006 (71 FR 6041), for SIO's SWPO survey. For this low-
energy seismic survey, the radius of the zone of potential serious 
injury for cetaceans is approximately 40 m (131 ft). For the 2-GI 
airgun seismic activity, the radius of the zone of potential Level B 
harassment for cetaceans is approximately 400 m (1312 ft). Considering 
the small size of the 2 GI-gun array compared to other high-energy 
sources used by the military and industry; the small size of the 
potential impact zones; the speed of the vessel when towing the airgun 
(7 knots); the length of daylight at this time of the year in the South 
Pacific; and, the marine mammal avoidance measures that are implemented 
by the vessel for marine mammals on the vessel's track, it is very 
unlikely that any marine mammals would enter the safety zone 
undetected. If a marine mammal enters the small safety zone, 
operational shutdown will be implemented until the animal leaves the 
safety zone.
    Comment 2: The Commission notes that NMFS and SIO believe that the 
proposed activities will result only in Level B harassment of cetaceans 
and pinnipeds. However, there is some possibility that the proposed 
study could result in injuries or deaths to beaked whales or other 
species of small cetaceans.
    Response: NMFS is unaware of any documented injuries or mortalities 
caused by low-energy, low-frequency sound sources, such as the 2 GI gun 
array on beaked whales or other marine mammals. If the Commission has 
any information on this subject, NMFS would appreciate obtaining this 
additional information for its review of IHA applications for low-
energy noise sources.
    Comment 3: The Commission states that NMFS and/or the applicant 
should provide additional information concerning the likely 
effectiveness of the proposed monitoring program in detecting an 
injured or dead beaked whale or other small cetacean, should an injury 
or death occur. For example, would any such animals likely be sighted 
from a ship running transects through an area or retracing recently run 
transect lines?
    Response: NMFS is unaware of any scientific studies to demonstrate 
efficacy of conducting marine mammal sightings from a moving vessel for 
incapacitated or dead marine mammals. However, SIO notes that the 
Revelle will spend approximately 24 hours at each of the 12 seabottom 
coring sites. As the inset to Figure 1 in SIO's application shows, the 
Revelle will run two parallel and one perpendicular seismic lines at 
each coring station. In addition, the Revelle will remain at the site 
for several hours while conducting its coring and magnetics work. Using 
big-eye binoculars, injured or dead mammals that are floating should be 
readily visible to MMOs during daylight hours.
    Comment 4: The Commission believes NMFS should require that 
operations be suspended immediately if a dead or seriously injured 
marine mammal is found in the vicinity of the operations and the death 
or injury could have occurred incidental to the seismic survey. Any 
such suspension should remain in place until NMFS has reviewed the 
situation and determined that further deaths or serious injuries are 
unlikely to occur or has issued regulations authorizing such takes 
under section 101(a)(5)(A) of the MMPA.
    Response: A standard condition in all seismic IHAs is for an 
emergency shut-down. The IHA states that ``If observations are made or 
credible reports are received that one or more marine mammals or sea 
turtles are within the area of this activity in an injured or mortal 
state, or are indicating acute distress, the seismic airguns will be 
immediately shut down and the Chief of the Permits, Conservation and 
Education Division, Office of Protected Resources or a staff member 
contacted. The airgun array will not be restarted until review and 
approval has been given by the Director, Office of Protected Resources 
or his designee.'' However, NMFS needs to make it clear that this 
requirement pertains only to recently deceased marine mammals (as 
determined by the lead MMO onboard the vessel) and not for long-dead 
``floaters.

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) and five species of pinnipeds (seals and sea lions) 
could potentially occur in the proposed seismic survey area 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. Please see these documents and NMFS' September 28, 2006 (71 FR 
56957) notice for additional information on potentially affected marine 
mammal species.

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

[[Page 75948]]

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, NMFS and SIO 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 mitigation and monitoring required under the 
IHA 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 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 in 71 FR 56955 
(September 28, 2006)).
    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 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 (see Table 5 in SIO's application). 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

[[Page 75949]]

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 (see 71 FR 56955 (September 28, 2006)) 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.

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 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 (see Table 2 in 71 FR 56955 
(September 28, 2006)). 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.
    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. 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

[[Page 75950]]

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.

Required 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 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 practicable to accomplish research objectives.
    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 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 practicable and safe, be 
revised 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 the outer perimeter of 
safety zone.

Shut-down Procedures

    Although power-down procedures are often standard operating 
practice for seismic surveys, power-down will not be used or authorized 
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 and 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 or an alternative ship speed or trackline is not effective in 
preventing entry into the safety zone, then the GI airguns must be shut 
down immediately. Likewise, if a mammal is already within the safety 
zone when first detected, the airguns must 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 minutes in the case of small odontocetes and pinnipeds, 
or (3) has not been seen within the zone for a minimum of 30 minutes 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

[[Page 75951]]

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 two experienced marine mammal observer on 
board the Revelle, 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, reticulated 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 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 call at night and available to assist 
the bridge watch if 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

    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, 
use the PAM system during this cruise is not warranted and, therefore, 
is not required.

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 determined that the required 
mitigation and monitoring ensures that the activity will have the least 
practicable impact on the affected species or stocks. Due to seismic 
sound propagation, 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 draft 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, which will be posted by NMFS on its 
web-site, 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)

    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).

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,

[[Page 75952]]

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 seismic activity by SIO, it is not necessary for NMFS to 
issue a new EA, a supplemental EA or an environmental impact statement 
for the 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).

Conclusions

    NMFS has 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 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 required 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 and will not affect marine mammals used for subsistence 
purposes.

Authorization

    On this date, NMFS issues an IHA to SIO to take marine mammals, by 
Level B harassment, incidental to conducting seismic surveys in the SPO 
for a 1-year period, provided the mitigation, monitoring, and reporting 
requirements are undertaken.

    Dated: December 12, 2006.
Donna Wieting,
Deputy Director, Office of Protected Resources, National Marine 
Fisheries Service.
[FR Doc. E6-21611 Filed 12-18-06; 8:45 am]
BILLING CODE 3510-22-S