Small Takes of Marine Mammals Incidental to Specified Activities; Marine Seismic Survey off the Aleutian Islands in the North Pacific Ocean, 44901-44913 [05-15374]

Agencies

• DEPARTMENT OF COMMERCE
• National Oceanic and Atmospheric Administration

[Federal Register Volume 70, Number 149 (Thursday, August 4, 2005)]
[Notices]
[Pages 44901-44913]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 05-15374]


-----------------------------------------------------------------------

DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

[I.D. 020405A]


Small Takes of Marine Mammals Incidental to Specified Activities; 
Marine Seismic Survey off the Aleutian Islands in the North Pacific 
Ocean

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

ACTION: Notice of issuance of an incidental harassment authorization.

-----------------------------------------------------------------------

SUMMARY: In accordance with provisions of the Marine Mammal Protection 
Act (MMPA) as amended, notification is hereby given that an Incidental 
Harassment Authorization (IHA) to take small numbers of marine mammals, 
by harassment, incidental to conducting oceanographic seismic surveys 
in the Aleutian Island area has been issued to Lamont-Doherty Earth 
Observatory (L-DEO).

DATES: Effective from July 18, 2005 through July 17, 2006.

ADDRESSES: The application and authorization are available by writing 
to Steve Leathery, Chief, Permits, Conservation and Education Division, 
Office of Protected Resources, National Marine Fisheries Service, 1315 
East-West Highway, Silver Spring, MD 20910-3225, by telephoning the 
contact listed here and are also available at: https://
www.nmfs.noaa.gov/prot_res/PR2/Small_Take/smalltake_
info.htm#applications. Documents cited in this notice can be viewed by 
appointment during regular business hours at the address provided here.

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 may be granted if NMFS finds that the taking will 
have a negligible impact on the species or stock(s), will not have an 
unmitigable adverse impact on the availability of the species or 
stock(s) for subsistence uses, and that the permissible methods of 
taking and requirements pertaining to the monitoring and reporting of 
such takings are set forth. NMFS has defined ``negligible impact'' in 
50 CFR 216.103 as ''...an impact resulting from the specified activity 
that cannot be reasonably expected to, and is not reasonably likely to, 
adversely affect the species or stock through effects on annual rates 
of recruitment or survival.''
    Section 101(a)(5)(D) of the MMPA established an expedited process 
by which citizens of the United States can apply for an authorization 
to incidentally take small numbers of marine mammals by harassment. 
Except 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 December 23, 2004, NMFS received an application from L-DEO for 
the taking, by harassment, of several species of marine mammals 
incidental to conducting a low-energy, shallow-penetrating seismic 
survey and scientific rock dredging program around the Aleutian 
Islands. The purpose of the proposed study is to examine the east-to-
west change in the angle of the convergence of the Pacific-North 
America plates, which implies systematic westward decreases in the rate 
of subduction and sediment delivery to the Aleutian trench. The 
Aleutian Island Arc is the only island arc where systematic changes in 
physical aspects of the subduction system have been well correlated 
with magma output rates and with the geochemistry of the melts that the 
system produces. Despite its potential importance, studies of volcanism 
in the Aleutians are lacking. In particular, the western Aleutians 
(west of Adak Island) are now playing a key role in the evolving view 
of subduction magma genesis, yet it remains a poorly studied area. Few 
volcanic rock samples are available from that area, and it has not been 
studied substantially at sea.
    In addition to an emphasis on magma genesis and its relationship to 
tectonics, volcanism in the Aleutians and southern Alaska is important 
because it is known to present a hazard to air traffic. However, the 
seismic and geochemical studies proposed by L-DEO are not directly 
hazard-related. They are aimed at understanding the deep-level 
processes that underlie the volcanic eruptions, and are thus relevant 
to the broad goals of understanding volcano behavior and hazard 
assessment in the Aleutians and elsewhere.

Description of the Activity

    The seismic survey will involve one vessel, the R/V Thomas G. 
Thompson (Thompson). The Thompson replaces the R/V Kilo Moana that was 
originally proposed for use during this survey. The Thompson will 
deploy one Generator-injector (GI) airgun as an energy source 
(discharge volume of 105 in3), plus a towed hydrophone streamer up to 
300 m (984 ft) long, or possibly as short as

[[Page 44902]]

50 m (164 ft). The Thompson has a length of 83.5 m (274 ft), and a beam 
of 16 m (52.5 ft). As the GI gun is towed along the survey lines, the 
receiving system will receive the returning acoustic signals. The 
proposed program will consist of approximately 4112 km (2220 nm) of 
seismic survey, and scientific rock dredging at 10 locations. The 
seismic survey will take place in water depths from less than 50 m (164 
ft) to 3.5 kilometers (km) (1.9 nautical miles (nm)). More than 99 
percent of the survey will be in depths greater than 100 m (328 ft), 
and scientific rock dredging will be conducted in water depths 100-1800 
m (328-5906 ft), mostly in depths greater than 400 m (1312 ft).
    The proposed program will use conventional seismic methodology with 
a single towed GI-airgun as the energy source, and a towed hydrophone 
streamer as the receiver system. The energy to the airguns is 
compressed air supplied by compressors on board the source vessel.
    In addition to the GI gun, additional acoustic systems will be 
operated during much or all of the research cruise. The ocean floor 
will be mapped with a 30-kHz multi-beam sonar (Simrad EM300) and a 
dual-frequency (3.5 and 12 kHz) hydrographic echo sounder (Knudson 
320B/R). These two systems are commonly operated simultaneously with an 
airgun array. Other acoustical systems are a 75-kHz acoustic Doppler 
current profiler (ADCP)(RDI Ocean Surveyor), a Hydrosweep multi-beam 
sonar will be used as a backup to the Simrad, an 80-kHz navigational 
echosounder (Abyss Technologies Model IES-10) and a 200-kHz doppler 
sonar (Ocean Data Equipment Corporation DSN-450 Mark II). Multi-beam 
bathymetric and single channel surveys will be conducted prior to 
scientific rock dredging to ensure that dredging is done as accurately 
and productively as possible. The surveys will also affect the number 
of dredges that can be completed. While on station for rock dredging, a 
12-kHz pinger will be used to monitor the depth of the dredge relative 
to the sea floor. A detailed description of the acoustic sources 
proposed for use during this survey can be found in the L-DEO 
application, which is available at: https://www.nmfs.noaa.gov/prot_res/
PR2/Small_Take/smalltake_info.htm#applications.

GI-Airgun Description

    The L-DEO portable high-resolution seismic system will be installed 
on the research vessel for this cruise. The seismic vessel will tow the 
single GI-airgun and a streamer containing hydrophones along 
predetermined lines. Seismic pulses will be emitted at intervals of 5-
10 sec. The 5-10 sec spacing corresponds to a shot interval of about 
13-26 m (43-85 ft).
    The GI airgun will have a total discharge volume of up to 105 
in\3\. The gun will be towed 44.3 m (145.3 ft) behind the stern at a 
depth of about 3 m (9.8 ft). The GI-airgun has a zero to peak (peak) 
source output of 231 dB re 1 microPascal-m ( 3.6 bar-m) and a peak-to-
peak (pk-pk) level of 237 dB (7.0 bar-m). The dominant frequency 
components of the airgun are in the range of 0-188 Hz. For a one-gun 
source, the nominal source level represents the actual level that would 
be found about 1 m (3.3 ft) from the GI gun. Actual levels experienced 
by any marine organism more than 1 m (3.3 ft) from the GI gun will be 
significantly lower.
    The rms (root mean square) received levels that are used as impact 
criteria for marine mammals are not directly comparable to the pk or 
pk-pk values normally used to characterize source levels of airguns. 
The measurement units used to describe airgun sources, pk or pk-pk 
decibels, are always higher than the ``root mean square'' (rms) 
decibels referred to in much of the biological literature. The rms 
pressure is an average over the pulse duration. For example, a measured 
received level of 160 dB rms in the far field would typically 
correspond to a pk 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, 2000a). The precise difference between rms and pk or p-pk values 
depends on the frequency content and duration of the pulse, among other 
factors. However, the rms level is always lower than the pk or pk-pk 
level for an airgun-type source.
    The depth at which the source is 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 source to be used in this 
project is 3 m (9.8 ft), where the ambient pressure is 3 decibars. This 
also limits output, as the 3 decibars of confining pressure cannot 
fully constrain the source output, with the result that there is loss 
of energy at the sea surface.
    Received sound levels have been modeled by L-DEO for the single GI-
airgun in relation to distance and direction from the gun. This 
publically available model does not allow for bottom interactions, and 
is most directly applicable to deep water. Based on the model, the 
distances from the single GI-airgun where sound levels of 190-, 180-, 
and 160-dB re 1 microPa (rms) are predicted to be received are shown in 
the greater than 1000-m (328 ft) line of Table 1.

 Table 1. Estimated distances to which sound levels 190, 180, and 160 dB
  re 1 microPa (rms) might be received from the one 105 in3 GI gun that
   will be used during the seismic survey around the Aleutian Islands
   during 2005. The safety radii used during the survey will depend on
                         water depth (see text).
------------------------------------------------------------------------
                                                 Estimated Distances at
                                                  Received Levels (m)
                 Water depth                  --------------------------
                                                190 dB   180 dB   160 dB
------------------------------------------------------------------------
                  >1000 m                           10       27      275
                  100-1000 m                        15       41      413
                  <100 m                           125      200      750
------------------------------------------------------------------------

    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 27 May to 3 June 
2003 (Tolstoy et al., 2004a,b). 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), vary with water depth. Similar depth-related 
variation is likely in the 190-dB isopleth that is applicable to 
pinnipeds. The 180- and 190-dB distances are typically used as safety 
radii during seismic surveys. For all sea turtle sightings, the 180-dB 
distance will be used as the safety radius. The proposed study area 
will occur in water approximately 30-3000 m (98-9842 ft), although only 
about 3 percent of the survey lines are expected to occur in shallow 
(<100 m; 328 ft) water.
    The empirical data indicate that, for deep water (>1000 m; 3281 
ft), the L-DEO model tends to overestimate the received sound levels at 
a given distance (Tolstoy et al., 2004a,b). However, to be 
precautionary pending acquisition of additional empirical data, L-DEO 
has proposed using safety radii during GI-airgun operations in deep 
water that correspond to the values predicted by L-DEO's model for deep 
water (Table 1). The assumed 190- and 180-dB radii for one GI-airgun 
are 10 m (33 ft) and 27 m (88 ft), respectively.
    Empirical measurements were not conducted for intermediate water

[[Page 44903]]

depths (100-1000 m (328-3281 ft)). On the expectation that results will 
be intermediate between those from shallow and deep water, L-DEO has 
applied a 1.5X correction factor to the estimates provided by the model 
for deep water situations. This is the same factor that was applied to 
the model estimates during L-DEO cruises in 2003. The assumed 190 and 
180 dB radii in intermediate-depth water are 15 m (49 ft) and 41 m (134 
ft), respectively (Table 1). L-DEO has requested NMFS use these values 
for calculating safety ranges in intermediate-depth waters.
    Empirical measurements were not made for a single small source 
operating in shallow water (<100 m (328 ft)). However, the measured 
180-dB radius for the 6-airgun array operating in shallow water was 
6.8X that predicted by L-DEO's model for operation of the 6-airgun 
array in deep water. This conservative correction factor was used to 
predict the radii for two GI airguns. The radii for one GI-airgun were 
assumed to be half of that predicted for two GI guns. Thus, the 190- 
and 180-dB radii in shallow water are assumed to be 125 m (410 ft) and 
200 m (656 ft), respectively (Table 1) and L-DEO has requested NMFS use 
these values for establishing safety zones in shallow water.

Characteristics of Airgun Pulses

    Discussion on the characteristics of airgun pulses have been 
provided in the application and in previous Federal Register notices 
(see 69 FR 31792 (June 7, 2004) or 69 FR 34996 (June 23, 2004)). 
Reviewers are referred to those documents for additional information.

Comments and Responses

    A notice of receipt and request for 30-day public comment on the 
application and proposed authorization was published on March 21, 2005 
(70 FR 13466). During the 30-day public comment period, comments were 
received from the Marine Mammal Commission (Commission), the Center for 
Biological Diversity (CBD) and L-DEO.

Activity Concerns

    Comment 1: L-DEO noted that the seismic vessel will be the Thompson 
and the scheduled cruise dates have been modified. The cruise will 
begin on July 19, 2005. Also, the Thompson has different sonar 
instrumentation than the R/V Kilo Moana.
    Response: NMFS has made the appropriate changes and analyses in 
this document.

Marine Mammal Protection Act Concerns

    Comment 2: The CBD believes NMFS has not demonstrated that the LDEO 
project will take only small numbers of marine mammals.
    Response: NMFS believes that the small numbers requirement has been 
satisfied. The U.S. District Court for the Northern District of 
California held in NRDC v. Evans that NMFS' regulatory definition of 
``small numbers'' improperly conflates it with the ``negligible 
impact'' definition. Even if that is the case, in the proposed IHA 
notice and in this document, NMFS has made a separate determination 
that the takes of the affected marine mammal species will be small. The 
species most likely to be harassed during the seismic survey is the 
Dall's porpoise, with a ``best estimate'' of 376 animals being exposed 
to sound levels of 160 dB or greater. This represents less than 0.1 
percent of the Alaska regional population of that species, a relatively 
small number. Moreover, this does not mean that 376 Dall's porpoises 
will be taken by Level B harassment. Dall's porpoise have their best 
hearing at high frequencies, not the low frequencies used by seismic 
airguns and may not even hear seismic sounds. If in fact, Dall's 
porpoise cannot hear the low-frequency seismic sounds, then no taking 
of this species will occur. Finally, NMFS notes that during this 
project, no marine mammal stock other than the killer whale stock will 
exceed 1 percent of its stock being potentially subject to Level B 
harassment. For killer whales a best estimate is that about 46 animals, 
or about 3.1 percent of the Alaska population, will be exposed to low-
frequency noise. See Table 2 for more information on Level B harassment 
take estimates.
    Comment 3: The CBD believes that NMFS does not define the 
geographical limits of the ``regional'' populations that form the basis 
of its anlysis or provide an analysis of impacts on stocks that overlap 
the project area. The appropriate geographical scale should be 
populations and stocks inhabiting the survey area, not the entire 
``northeast Pacific Ocean.'' Any analysis of small numbers and 
negligible impact cannot be conducted independently of this 
information. For example, for the killer whale, NMFS does not mention 
or distinguish between transient, offshore, and resident stocks that 
all exist in the Aleutian Islands. As a result, the requested 
authorization for a take of 157 killer whales is not of detailed enough 
scale to permit reasoned analysis of the small numbers and negligible 
impact requirements. This analysis must be redone for this and other 
species.
    Response: NMFS agrees that impacts should be assessed on the 
population or stock unit whenever possible. L-DEO's application (see 
especially Table 4) provides information on stock abundance in the 
northern Gulf of Alaska and Aleutian Islands (when available) and 
larger water bodies (such as the North Pacific Ocean). The data source 
for each stock estimate is provided. NMFS believes that these data are 
the best scientific information available for estimating impacts on 
marine mammal species and stocks. However, information on marine mammal 
stock abundance may not always be satisfactory. When information is 
lacking for defining a particular population or stock of marine mammals 
then impacts are assessed with respect to the species as a whole (54 FR 
40338, September 29, 1989). As a result, NMFS disagrees that this 
analysis must be redone. For example, information on the killer whale 
stocks was provided on pages 16 and 17 of the L-DEO application and in 
NMFS' proposed authorization (see 70 FR 13466, March 21, 2005 
especially Table 2). It was not separated out for additional discussion 
in NMFS' notice since, as noted later, the killer whale is less likely 
to be impacted than most other species and, therefore, did not warrant 
additional analysis. For clarification in calculating killer whale 
density, L-DEO used the survey data of Wade et al. (2003) and Zerbini 
et al. (2004) for the Northern Gulf of Alaska and Aleutian Islands. 
Referencing these recent marine mammal surveys, L-DEO notes that the 
best scientific information currently available indicates that 66 
percent of the killer whale groups sited were resident, 24 percent were 
transient, 3 percent were offshore, and 7 percent were unknown. On June 
3, 2004 (69 FR 31321), NMFS published a rule designating the AT1 killer 
whale group of the transient stock as a depleted stock under the MMPA. 
This group, found east of the Aleutians and, therefore, unlikely to be 
affected, has 9 or fewer whales and was part of the Eastern North 
Pacific Transient stock prior to this designation.
    Since there is insufficient information to indicate which of these 
stocks, if any, might be within the relatively small impact area at the 
same time the Thompson is conducting seismic, NMFS believes the proper 
method is to divide the estimated incidents of harassment among the 
current stocks. Since this species is unlikely to be in the vicinity of 
the Thompson at the time seismic is operating (L-DEO, 2004), and is 
highly

[[Page 44904]]

visible to observers, no killer whales will be injured or killed (i.e., 
no removals from the species or stock) as a result of the Thompson's 
seismic operations. Therefore, the only potential taking might be by 
Level B harassment. As indicated in Table 2 in this document, L-DEO has 
provided a best estimate that approximately 46 killer whales (maximum 
estimate, 144) might be within the 160-dB (rms) isopleth and, 
therefore, presumed to be harassed. Forty-six individuals is 3.1 
percent of the Alaska regional killer whale population. If subdivided 
according to stock size, NMFS estimates that approximately 32 Resident, 
12 Transient and less than 2 Offshore killer whales may be within the 
160 dB isopleth. Moreover, since the killer whale's optimum hearing 
range is not in the low frequency used by seismic sources, this number 
should not be interpreted as the number being ``taken'' by Level B 
harassment, only the number that might be exposed to seismic noise at 
SPLs greater than or equal to 160 dB. Therefore, NMFS believes that the 
effect of any taking will be negligible.
    Comment 4: The CBD states that the application provides Alaskan 
population estimates for the following species: sperm whale, beluga 
whale, Pacific white-sided dolphin, killer whale, harbor porpoise, 
Dall's porpoise, humpback whale, minke whale, Steller sea lion and 
harbor seal. However, the proposed authorization neglects to explain 
how this delineation corresponds to populations or stocks or to use 
this information for its take estimates. For example, the application 
estimates the northern Gulf of Alaska (GOA) and Aleutian Island 
population of humpback whales to be 2,866 individuals. Yet, the 
proposed authorization's best estimate of how many humpback whales will 
be exposed to sound levels greater than 160 dB is 54 individuals, which 
it concludes represents only 0.9 percent of the ``regional 
population.'' However, 54 individuals represents 1.8 percent of the 
northern GOA and Aleutian population of humpback whales, which is the 
proper geographic scope of the take analysis. The same flaw pervades 
NMFS' take analysis for those species for which Alaskan populations are 
known. It is also unclear how some Alaska populations (e.g., Steller 
sea lion, harbor porpoise) are listed as larger than their regional 
populations.
    Response: NMFS recognizes that there is some confusion in the 
presentation of the regional population estimates. In a few cases, such 
as the killer whale, minke whale, and harbor porpoise, the population 
estimates for various parts of the relevant range are listed in the 
table rather than the sum of all of the estimates. For most species/
stocks the numbers of individuals exposed are so small that the stock 
proportions are still very small even though the regional population is 
understated. However, for the killer whale the stock proportions 
potentially affected are larger, so L-DEO estimated the regional 
population.
    The L-DEO application contains very detailed descriptions of the 
biology, distribution and movements of all species considered to be 
potentially affected. With very few exceptions, the species have 
seasonal ranges much larger than the proposed northern GOA and 
Aleutians area for this survey. There are movements by specific 
individuals into and out of the GOA and Aleutians during any one season 
and in different years. The number of different individuals of a 
species that uses an area is much larger than the number that is there 
at any specific time. Thus any potential impacts on the proportion of 
the population must reflect all individuals that use the area, which is 
best reflected in the regional population estimate. In addition, in 
almost all cases, the regional population estimates are from only part 
of the range of the stock, and the real population/stock sizes are 
likely much larger. Therefore, using the regional abundance estimates 
to estimate the proportions of populations that might be impacted is 
conservative because the actual regional abundance is usually much 
higher than the estimates that are presented, and the actual proportion 
of the population affected is likely lower than estimated proportion 
affected.
    The killer whale is one species that has resident populations that 
typically do not wander throughout the killer whale range, but they 
also have transient populations that do move throughout the North 
Pacific Ocean (NPO). Therefore, the number of different individuals 
that might be impacted is somewhere between the northern GOA and 
Aleutians estimate (1472) and the sum of the southern and northern 
estimates (2812) (or higher since much of the offshore habitat has not 
been surveyed and therefore is not included in the two estimates). In 
this case, L-DEO has conservatively considered only the Alaska 
population estimate rather than the Regional abundance, but a better 
(but still very conservative) estimate of the Regional population size 
for killer whales is 2063 as described here. Perhaps the percentage 
that might be impacted should reflect the still very conservative 
estimate of 2063 for the Regional population size. Therefore, the 
estimate of the regional population affected by this activity should be 
somewhere between 1472 and 2812 (or higher) consisting of (1) the 
Resident populations in the south (Washington-Oregon- California and 
Southern British Columbia, 83 based on Carretta et al. 2005), plus (2) 
the resident population in Alaska (723 based on Angliss and Lodge 2004) 
plus (3) the transient population that ranges throughout California to 
Alaska, plus (4) the Offshore population that ranges farther offshore 
from California to Alaska. Based on the estimate of 1340 killer whales 
that occur within 300 nm of the CA/OR/WA coastline and assuming that 83 
of these whales are the southern resident population (see previous 
comment), then there are at least 1257 transient and offshore killer 
whales in the CA/OR/WA population. If we add these to the resident 
numbers for CA/OR/WA/BC (83) and Alaska (723), the minimum regional 
population size is 2063. This is very conservative for a number of 
reasons: only identified animals are counted as residents (some 
unidentified animals are likely to exist and some animals that have 
been photographed have not been assigned to any of the populations); 
all of the southern resident population of 83 was assumed to be in the 
CA/OR/WA survey area though probably only a few were there at the time 
of the survey; only a small part of the offshore habitat has been 
surveyed and therefore is included in the estimate; and it is assumed 
that all offshore and transient whales seen off Alaska are part of the 
estimate for CA/OR/WA and at the time of the survey some killer whales 
are likely to have been present in BC or Alaska waters and are not 
included in the above estimate.
    Comment 5: The CBD states that surveys should be conducted prior to 
authorizing the IHA for those species for which the Alaskan marine 
mammal populations are not known, asserting that any analysis of small 
numbers and negligible impact cannot be conducted independently of this 
more detailed information.
    Response: NMFS disagrees. As noted previously, when information is 
unavailable on a local population stock size, NMFS uses either stock or 
species information on abundance. Since NMFS uses the best information 
that is available, estimating impacts on marine mammals in this manner 
is appropriate. Therefore, additional surveys are unnecessary.
    Comment 6: The Commission believes that NMFS' preliminary 
determinations are reasonable if the proposed mitigation and monitoring 
activities are

[[Page 44905]]

adequate to detect marine mammals in the vicinity of the proposed 
operation and to ensure that marine mammals are not being taken in 
unanticipated ways or numbers. The Commission remains concerned about 
whether the proposed monitoring effort will be sufficient to determine 
that no marine mammals are within the safety zones at start-up or will 
be an effective means of detecting when marine mammals enter the safety 
zone during operations. This is particularly true for cryptic species 
that may be difficult to detect. The need for effective monitoring is 
especially important in light of the diversity and abundance of marine 
mammal species in the western Aleutian Islands.
    Response: For this activity, the radius of the zone of potential 
impact ranges from 10 to 200 m (33 to 656 ft) depending upon water 
depth. Considering the small size of the conservative shutdown zones, 
the speed of the vessel when towing the airgun (9 kts), the length of 
daylight at this time of the year, and the marine mammal avoidance 
measures that are implemented by the vessel for animals 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 7: The Commission recommends that if the proposed 
monitoring and mitigation measures do not provide sufficient assurance 
that marine mammals will not be exposed to sound levels that may cause 
serious injuries or mortalities, authorization of these additional 
types of taking should be pursued under section 101(a)(5)(A) of the 
MMPA.
    Response: As noted in this document and in previous documents, the 
best scientific information indicates that marine mammals are unlikely 
to be injured or killed incidental to seismic operations unless the 
sound pressure level (SPL) is significantly above the levels calculated 
for the safety zone established to prevent injury. For this research 
cruise, using only a single airgun, the conservative 180 dB (cetacean) 
and 190-dB (pinniped) safety zones will vary from 10-27 m (33-88.6 ft) 
in deep water to 125-200 m (410-656.2 ft) in shallow (<100 ft (30.5 m) 
water. With approximately 97 percent of the survey conducted in deep 
water, with the Thompson's length at 83.5 m (274 ft), and a beam of 16 
m (52.5 ft), and with the hydrophone streamer extending 300 m (984 ft) 
long (or possibly as short as 50 m (164 ft)) astern of the Thompson 
during most of the survey, the safety zones will not extend beyond the 
perimeter of the vessel and its hydrophone array. Therefore, no marine 
mammals are likely to be injured or killed by the Thompson's research 
cruise and the issuance of an IHA is appropriate.

Mitigation and Monitoring Concerns

    Comment 8: The CBD states that there is no discussion or 
consideration of additional monitoring or mitigation measures, such as 
use of passive acoustics. Without requiring such additional measures, 
or at a minimum discussing why they are not practical, NMFS cannot 
lawfully issue the requested authorization.
    Response: Prior to issuing an IHA, NMFS thoroughly investigates all 
measures that might reduce the incidental taking of marine mammals by 
an activity to the lowest level practicable. Some of these mitigation 
measures are mentioned elsewhere in this document. Mitigation measures, 
such as aerial overflights or support vessels to look for marine 
mammals prior to an animal entering a safety zone, are generally given 
consideration if the safety zone cannot be adequately monitored from 
the source vessel. Additional consideration must be given to aircraft/ 
vessel availability, access to nearby airfields, aircraft flight 
duration and personnel safety. There are serious safety issues 
regarding aircraft flights over water that must be considered prior to 
requiring aerial overflights. Additional consideration must be given to 
the potential for the aircraft itself to also result in Level B 
harassment since a plane or helicopter would need to fly at low 
altitudes to be effective. Because the safety zones for this proposed 
activity are very small and can be easily monitored from the Thompson, 
use of aircraft for mitigation purposes is not warranted. Also, because 
of the small size of the airgun and its zone of marine mammal 
influence, beach monitoring for strandings is unnecessary.
    The 180-dB safety radius for the single airgun is 27 m (88.6 ft) in 
deep water, 41 m (134.5 ft) in intermediate-depth waters and 200 m 
(656.2 ft) in shallow water. Because of the relatively small safety 
zones, accurately locating vocalizing marine mammals to determine 
presence within the safety zone by passive acoustic monitoring (PAM) is 
not practicable with existing technology. Detecting vocalizing marine 
mammals to determine presence simply alerts observers to their presence 
and does not initiate shutdown because PAM cannot accurately determine 
distance and bearing to the vocalizing animal. At such short distances, 
a trained marine mammal observer should not have difficulty locating 
them visually without the PAM. Of the 4111 km (2220 nm) of seismic 
lines for this survey, the major portion (4080 km (2203 nm)) will be in 
intermediate or deep water where the safety zones are very small. In 
shallow water, where the safety zone will be slightly larger, the PAM 
has proven inefficient due to signal propagation loss and reflection 
characteristics in shallow water. For these reasons, NMFS is not 
requiring L-DEO to use the PAM during the Aleutian Islands research 
program.
    Comment 9: The CBD questions NMFS permitting the airgun to remain 
operational throughout the night if it has been operational before 
nightfall, even though the entire safety radius may not be visible.
    Response: Standard procedures set in 1994 by NMFS marine mammal 
scientists for Beaufort Sea seismic operations allow airguns to 
continue to operate after nightfall if the airgun was ramped up during 
daylight hours with the entire safety radius visible at the time of 
ramp-up. It is widely presumed that marine mammals that are capable of 
hearing low-frequency airgun noises will avoid the area, and, 
therefore, injury if they find the noise annoying. Years of observation 
of bowhead whales in the Beaufort Sea indicate this species avoids the 
source of seismic sounds by tens of kilometers. NMFS presumes that 
other species will also take similar avoidance measures. However, for 
this research cruise, the safety radii are so small that they will be 
fully visible from the vessel, day or night. Night-time observations 
will utilize night vision devices (NVDs) if darkness precludes safety-
zone observations.
    In 2003, L-DEO completed two tests of the effectiveness of 
monitoring using NVDs (Smultea and Holst 2003, Appendix C; Holst 2004, 
Appendix B). Results of these tests indicated that the Night Quest 
NQ220 NVD is effective at least to 150 to 200 m (492 to 656 ft) away 
under certain conditions. That is sufficiently within the range of the 
NVDs to allow detection of marine mammals visually within the area of 
potential TTS. Furthermore, most marine mammals that might be within 
that distance would be expected to move away to avoid airgun operations 
as the vessel approaches.
    Comment 10: The Commission recommends that NMFS seek clarification 
of two aspects of the proposed mitigation and monitoring measures. The 
application indicates that marine mammal observers would be on duty 
during all ``daytime'' airgun operations and that no start-up of the

[[Page 44906]]

airguns would occur at night unless the safety zones were visible. In 
the Aleutian Islands during the month of June there are about 17 hours 
between sunrise and sunset, and it will be light enough to monitor the 
safety zones for some time before sunrise and after sunset. Therefore, 
the Commission recommends NMFS more explicitly define what constitutes 
daytime and nighttime for purposes of these mitigation measures.
    Response: Marine mammal observers begin observations when daylight 
allows them to make marine mammal behavioral observations in the area 
within the 160-dB isopleth.
    Comment 11: The Commission notes that the application does not 
contain sufficient information with respect to the proposed track lines 
to allow reviewers to assess the likelihood of the applicant's proposal 
to look for animals possibly injured or killed on recently completed 
parallel transects. It would be useful if the applicant were to provide 
additional information as to how close track lines are likely to be and 
to estimate the time that is likely to transpire between passes through 
nearby locations.
    Response: Figure 1 in the application provides a visual 
illustration of the proposed track lines. Accessing that same figure 
via the on-line electronic copy allows an interested reviewer to 
magnify this illustration to better determine distances. Because the 
chart is to scale, and the vessel towing speed is about 9 knots (16.7 
km/hr), one can easily calculate the time and distance between transit 
lines if that information is needed to assess monitoring effectiveness. 
However, for this survey, using a single low-intensity airgun, serious 
injury or mortality is unlikely since SPLs that might cause injury or 
mortality would not extend beyond the vessel's footprint (see 
discussion on hearing impairment in the proposed IHA notice (70 FR 
13466, March 21, 2005)). When necessary, L-DEO provides spreadsheets to 
NMFS containing this information.
    Comment 12: The Commission notes that the applicant does not plan 
to monitor received noise levels during the survey. The Commission 
believes that monitoring would be useful for data gathering and animal 
safety purposes. In addition, the Commission recommends that NMFS, if 
it has not already done so, notify NMFS' Alaska Fisheries Science 
Center researchers working in this area about the planned seismic work.
    Response: Successful acoustic monitoring requires a second vessel, 
which is not available for this cruise. As indicated in Tolstoy et al. 
(2003) (available online at https://www.nmfs.noaa.gov/pr/readingrm/
mmpa_small_take/gom_90d_report_final.pdf), acoustic measurements 
of the L-DEO array were made during the Gulf of Mexico calibration 
study. The results from that study are provided in this document. In 
summary, the single GI-airgun proposed for use during this survey has 
an impact zone significantly less than airguns used during regular 
seismic surveys. Airgun attenuation and propagation measurements will 
be made on an opportunistic basis whenever possible, but considering 
the location, the small size of the airgun, and the cost to conduct 
measurements, NMFS does not consider this recommendation to be 
warranted. As recommended, NMFS notified its scientists working in the 
Aleutian Island area of the proposed low-intensity seismic survey this 
summer.
    Comment 13: The Commission and CBD note that the applicant states 
that Steller sea lion critical habitat and ``no approach'' zones occur 
within the proposed study area, and that the applicant has stated that 
such areas around haul-outs and rookeries will be avoided to the extent 
``practicable.'' The Commission recommends that any IHA issued be 
conditioned to require that critical habitat areas, ``no approach'' 
zones, and other areas where there is commonly a high density of 
pinnipeds (including females and pups during June and July) be avoided 
to the extent possible. The CBD believes more appropriate and legally 
required alternative is for NMFS to require L-DEO to reschedule the 
project to avoid this sensitive time altogether. Also, the Commission 
considers it prudent for the applicant to avoid other marine mammal 
concentration areas, such as passes.
    Response: ``No-approach'' zones and critical habitat for Steller 
sea lions are year-round designations so rescheduling is not a viable 
option. Also, surveys later in the year could compromise the survey's 
success and marine mammal monitoring due to weather. NMFS has 
established additional mitigation measures to protect critical habitat 
areas during this seismic survey. First, L-DEO will comply with the 
requirements of 50 CFR 223.202(a)(2)(i) and will not approach within 3 
nm (5.5 km) of a Steller sea lion rookery site. In addition, the IHA 
prohibits SPLs at 190 dB or greater within 3 nm (5.5 km) of a Steller 
sea lion rookery. For this action, L-DEO will monitor a safety/shutdown 
radius of 750 m (2461 ft) around the airgun for Steller sea lions 
whenever the seismic survey is taking place within designated critical 
habitats, regardless of the depth of water. Critical habitats in the 
areas of the survey include 20 nm (37 km) surrounding all Steller sea 
lion haulouts and rookeries as well as the Seguam Pass Foraging Area 
and Bogoslof Foraging Area (see Figure 3 in the L-DEO application). If 
any Steller sea lions are found in or seen approaching the safety zone, 
L-DEO will shut-down the airgun. Finally, this safety zone will be 
monitored for Steller sea lions prior to start-up of the airgun for at 
least 30 minutes when in designated critical habitats.
    Additional mitigation measures recommended by the Commission have 
not been accepted by NMFS since such a requirement would have the 
potential to unnecessarily compromise the proposed activity's success. 
NMFS believes that areas of high concentration of marine mammals could 
result in increased numbers of shutdowns. If shutdowns become 
significant, valuable ship time could be lost and a decision might be 
made to move to a different area. This is preferable to NMFS and L-DEO 
than simply making areas off limits due to a theoretical higher 
abundance of marine mammals.

Endangered Species Act (ESA) Concerns

    Comment 14: The CBD states that L-DEO's proposed project may affect 
8 species listed as endangered under the ESA. As a result, consultation 
under section 7 of the ESA must occur prior to authorization of the 
project. In addition, there is a stock of sea otters present in the 
proposed survey area that has recently been proposed for listing as 
``threatened,'' thus necessitating a conference.
    Response: Consultation under section 7 of the ESA for both NMFS and 
the U.S. Fish and Wildlife Service (USFWS) species has been completed. 
The NMFS biological opinion resulting from that consultation concluded 
that this action is not likely to jeopardize the continued existence of 
listed species or result in the destruction or adverse modification of 
critical habitat. Additional terms and conditions contained in the 
Incidental Take Statement for the protection of Steller sea lions have 
been implemented through the IHA (as discussed in the previous response 
to comment). On March 23, 2005, the USFWS determined that the proposed 
survey would not adversely affect sea otters or other species under its 
jurisdiction.

NEPA Concerns

    Comment 15: The CBD believes that the Environmental Assessment (EA) 
is insufficient and that an Environmental Impact Statement(EIS) is 
required. The

[[Page 44907]]

CBD states that NSF and NMFS have never prepared a comprehensive EIS 
that fully analyzes the environmental impacts of its seismic surveys, 
either individually or collectively, as well as provide the public with 
the critical opportunity to participate in the decision making process 
as required by NEPA for actions of this magnitude. The CBD believes 
that NMFS must prepare an EIS prior to approving this project.
    Response: NMFS disagrees. NMFS believes that the NSF EA provides an 
in-depth discussion on aspects of the impacts of the subject seismic 
survey on the marine environment, particularly marine mammals and sea 
turtles. It discusses and analyzes the potential interaction between 
marine mammals and seismic operations. In its review of NSF's EA for 
this action and previous L-DEO actions that were analyzed under 
individual EAs, NMFS has determined that the individual L-DEO actions 
are discrete actions that are dispersed geographically (e.g., Bermuda, 
Norway, Mid-Atlantic, Gulf of Mexico, Caribbean Sea, Eastern Pacific) 
and/or over time (Hess Deep, 2003 and Blanco Fracture, 2004). As a 
result, there are no cumulative effects because there are no removals 
from any marine mammal population, Level B harassment would affect 
relatively few mammals in widely disbursed marine mammal populations 
and those affects would not impact animals at the population level.
    NMFS announced the availability of the NSF EA for the Aleutan 
Island project on March 21, 2005 (70 FR 13466), as it does all NSF EAs. 
In the future, draft EAs will also be posted on NMFS' web-site. In 
conclusion, NMFS has determined that this project, as described in the 
NSF EA, does not raise substantial issues requiring an EIS.

Description of Habitat and Marine Mammals Affected by the Activity

    A detailed description of the Aleutian Islands area and its 
associated marine mammals can be found in the L-DEO application and a 
number of documents referenced in the L-DEO application. A total of 18 
cetacean species and 10 pinniped species may occur in the proposed 
study area around the Aleutian Islands. The marine mammals that occur 
in the proposed survey area belong to four taxonomic groups: 
odontocetes (toothed cetaceans, such as dolphins and sperm whales), 
mysticetes (baleen whales), pinnipeds (seals, sea lions, and walrus), 
and fissipeds (sea otter). Of the 18 cetacean species in the area, 
several are common.
    Odontocete whales include the sperm whale, Cuvier's beaked whale, 
Baird's beaked whale, Stejneger's beaked whale, beluga whale, Pacific 
white-sided dolphin, Risso's dolphin, killer whale, short-finned pilot 
whale, harbor porpoise, and Dall's porpoise;
    Mysticete whales include the North Pacific right whale, eastern 
North Pacific gray whale, humpback whale, minke whale, sei whale, fin 
whale, and blue whale;
    Pinnipeds include the northern fur seal, California sea lion, 
Steller sea lion, Pacific walrus, bearded seal, harbor seal, spotted 
seal, ringed seal, ribbon seal, and northern elephant seal. However, 
only four of these species of pinnipeds are likely to occur in the 
western Aleutian Islands: Steller sea lions, harbor seals, northern fur 
seals, and ribbon seals.
    The walrus, California sea lion, and ringed, spotted, bearded, and 
northern elephant seals likely will not be encountered in the study 
area although they are known to occur in the eastern Aleutians. The sea 
otter and the walrus are managed by the USFWS and are not the subject 
of this authorization.
    More detailed information on marine mammal species is contained in 
the L-DEO application.

Potential Effects on Marine Mammals

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

Effects of Seismic Surveys on Marine Mammals

    The L-DEO application and the proposed notice of an IHA for this 
project (see 70 FR 13466, March 21, 2005) provided information on what 
is known about the effects on marine mammals of the types of seismic 
and sonar operations planned by L-DEO. The types of effects analyzed in 
these documents are (1) tolerance, (2) masking of natural sounds, (2) 
behavioral disturbance, and (3) potential hearing impairment and other 
non-auditory physical effects (Richardson et al., 1995), including 
strandings. Please refer to those documents for information on those 
subjects.
    Given the relatively small size of the single airgun planned for 
the present project, its effects are anticipated to be considerably 
less than would be the case with a large array of airguns. L-DEO 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 275 m (902 ft) in deep water, 413 m (1355 ft) for 
intermediate water depths, and 750 m (2461 ft) in shallow water, the 
zones calculated for 160 dB or the onset of Level B harassment due to 
impulse sounds.
    The Thompson will use different sonars and acoustic equipment than 
the

[[Page 44908]]

Kilo Moana. However, the changes in mode of operation and energy or 
``noise'' output from the different gear are slight. The effects of the 
sonars on marine mammals are expected to be similar for the Thompson as 
discussed in the proposed notice for the Kilo Moana.
    The multi-beam bathymetric sonar that will be used on the Thompson 
has an operating frequency of 30 kHz. The multi-beam sonars that had 
been planned for use on the Kilo Moana were a Simrad EM120 for deep 
water (>800 m), operating at 11.25 and 12.6 kHz, and a Simrad EM1002 
for shallow water (10-800 m), operating at a frequency of 92 to 98 kHz. 
This leads to the following assessment:
    1. The Kilo Moana's deep water unit, which would have been used 
during the majority of the survey (approximately 66 percent), emits 
sound pulses centered at 12 kHz. Baleen whales that would have heard 
the 12-kHz sonar pulses from the Kilo Moana are unlikely to hear the 
30-kHz pulses from the Thompson.
    2. The difference in the operating frequencies will be 
insignificant to odontocetes and pinnipeds, which hear well at both 
frequencies.
    3. The Kilo Moana would have used a 98-kHz multi-beam in shallow 
waters, approximately 34 percent of the survey, whereas the Thompson 
will use its 30-kHz system in shallow as well as deep water. Pinnipeds 
are less sensitive to the higher frequencies, but mysticetes would not 
hear either the 98-kHz or 30-kHz sounds. For odontocetes, both 
frequencies are likely to be audible.
    4. The pulse lengths of the multi-beam sonars are not substantially 
different between the systems on the two vessels in either shallow or 
deep water. The Thompson's multi-beam has a pulse duration of 2 ms in 
shallow water and up to 15 ms in deep water; the Kilo Moana's multi-
beam has a pulse length of 0.2, 0.7, or 2 ms in shallow water and up to 
20 ms in deep water.
    Overall, effects on marine mammals from the multi-beam sonars on 
either vessel would be similar. For both vessels, the fore-aft beam 
width is narrow, so a marine mammal below the surface near the 
trackline is not likely to be exposed to strong sounds from more than 1 
(or a very few) pulses. The short durations of the pulses from either 
vessel mean that the energy received from one or a few pulses is low. 
Any effects induced by the multi-beam emissions are expected to be 
negligible with regard to masking and hearing impairment. Brief 
exposure to a few signals from any of the proposed multi-beam sonar 
systems might cause momentary, insignificant behavioral reactions in 
cetaceans and pinnipeds.
    The Thompson's hydrographic echosounder emits pulses at 3.5 and 12 
kHz whereas the Kilo Moana's sounder operates at 12, 38, and 200 kHz. 
The Kilo Moana's sounder would have been operated at the lower 
frequencies. The impact to marine mammals from the use of the 
Thompson's hydrographic echo sounder would be the same as, or perhaps 
less than, that from the Kilo Moana's hydrographic echo sounder.
    An ADCP will be used during the survey. The Thompson's ADCP 
operates at a frequency of 75 kHz, and the Kilo Moana's ADCP operates 
at 38 kHz. Neither system would be audible to baleen whales. Both 
systems will be audible to various species of odontocetes.

Estimates of Take by Harassment for the Aleutian Islands Seismic Survey

    Given the mitigation measures implemented by L-DEO (see Mitigation 
later in this document), all anticipated takes involve a temporary 
change in behavior that may constitute Level B harassment. The required 
mitigation measures will minimize or eliminate the possibility of Level 
A harassment or mortality. L-DEO has calculated the ``best estimates'' 
for the numbers of animals that could be taken by Level B harassment 
during the proposed Aleutian Islands seismic survey using data on 
marine mammal density and abundance from marine mammal surveys in the 
region by Brueggeman et al. (1987, 1988), Troy and Johnson (1989), 
Dahlheim et al. (2000), Waite et al. (2002), Doroff et al. (2003), Wade 
et al. (2003), and Tynan (2004), and estimates of the size of the 
affected area, as shown in the predicted RMS radii table (see Table 1).
    These estimates are based on a consideration of the number of 
marine mammals that might be exposed to sound levels greater than 160 
dB, the criterion for the onset of Level B harassment, by operations 
with the single GI-airgun planned to be used for this project. No 
animals are expected to exhibit responses to the sonars or pinger given 
their characteristics (e.g., narrow, downward-directed beam). 
Therefore, no additional incidental takings are included for animals 
that might be affected by the multi-beam sonars or 12-kHz pinger.
    Table 2 incorporates the corrected density estimates and provides 
the best estimate of the numbers of each species that would be exposed 
to seismic sounds greater than 160 dB. A detailed description on the 
methodology used by L-DEO to arrive at the estimates of Level B 
harassment takes that are provided in Table 2 can be found in L-DEO's 
IHA application for the Aleutian Islands survey.
BILLING CODE 3510-22-S

[[Page 44909]]

[GRAPHIC] [TIFF OMITTED] TN04AU05.000

BILLING CODE 3510-22-C

[[Page 44910]]

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 (Miller et al. in press). Fewer than 150 mysticetes 
are expected to be encountered during the proposed survey in the 
Aleutian Islands (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 delphinids 
and Dall's porpoise 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 single GI-airgun 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 odontocete cetaceans that may be exposed to sounds 
[gteqt]160 dB re 1 microPa (rms) represent 0 to approximately 0.4 
percent of the regional species populations, except for approximately 
3.1 percent for killer whales (Table 2).
    Mitigation measures such as controlled speed, course alteration, 
observers, 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 biological consequence. In light of the type of 
take 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

    Two pinniped species (the Steller sea lion and the harbor seal) are 
likely to be encountered in the study area. Also, it is possible that a 
small number of northern fur seals may be encountered, and possible 
(but very unlikely) that a few ribbon seals may be encountered. An 
estimated 56 individual harbor seals and 34 individual Steller sea 
lions (<0.1 percent and 0.2 percent of their northeast Pacific Ocean 
populations, respectively) may be exposed to GI gun sounds at received 
levels greater than or equal to 160 dB re 1 microPa (rms) during the 
seismic survey. It is probable that only a small percentage of those 
would actually be disturbed. It is most likely that only 3 northern fur 
seals and no ribbon seals will be exposed to sounds greater than or 
equal to 160 dB. Effects are expected to be limited to short-term and 
localized behavioral changes falling within the MMPA definition of 
Level B harassment. As with cetaceans, the short-term exposures to 
sounds from the single GI-airgun 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 temporarily displaced from 
this region prior to the approach of the airguns through avoidance 
reactions to the passing seismic vessel or to the airgun sounds as 
received at distances beyond the injury radius.
    Fish often react to sounds, especially strong and/or intermittent 
sounds of low frequency. Sound pulses at received levels of 160 dB re 1 
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. Some of the fish that do not 
avoid the approaching airguns (probably a small number) may be subject 
to auditory or other injuries.
    Zooplankton that are very close to the source may react to the 
airgun's 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.

[[Page 44911]]

Potential Effects on Subsistence Use of Marine Mammals

    Subsistence remains the basis for Alaska Native culture and 
community. Subsistence hunting and fishing continue to be prominent in 
the household economies and social welfare of some A