Takes of Marine Mammals Incidental to Specified Activities; Low-Energy Marine Seismic Survey in the Eastern Tropical Pacific Ocean Off Central and South America, October-November 2010, 54095-54114 [2010-22080]

Agencies

• DEPARTMENT OF COMMERCE
• National Oceanic and Atmospheric Administration

[Federal Register Volume 75, Number 171 (Friday, September 3, 2010)]
[Notices]
[Pages 54095-54114]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2010-22080]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

RIN 0648-XY12


Takes of Marine Mammals Incidental to Specified Activities; Low-
Energy Marine Seismic Survey in the Eastern Tropical Pacific Ocean Off 
Central and South America, October-November 2010

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

ACTION: Notice; proposed Incidental Harassment Authorization; request 
for comments.

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SUMMARY: NMFS has received an application from the Scripps Institution 
of Oceanography (SIO) of the University of California for an Incidental 
Harassment Authorization (IHA) to take marine mammals, by harassment, 
incidental to conducting a low-energy marine seismic survey. Pursuant 
to the Marine Mammal Protection Act (MMPA), NMFS is requesting comments 
on its proposal to issue an IHA to SIO to take, by Level B Harassment 
only, 21 species of marine mammals during the specified activity.

DATES: Comments and information must be received no later than October 
4, 2010.

ADDRESSES: Comments on the application should be addressed to Michael 
Payne, Chief, Permits, Conservation and Education Division, Office of 
Protected Resources, National Marine Fisheries Service, 1315 East-West 
Highway, Silver Spring, MD 20910. The mailbox address for providing e-
mail comments is PR1.0648-XY12@noaa.gov. NMFS is not responsible for e-
mail comments sent to addresses other than the one provided here. 
Comments sent via e-mail, including all attachments, must not exceed a 
10-megabyte file size.
    Instructions: All comments received are a part of the public record 
and will generally be posted to https://www.nmfs.noaa.gov/pr/permits/incidental.htm without change. All Personal Identifying Information 
(for example, name, address, etc.) voluntarily submitted by the 
commenter may be publicly accessible. Do not submit Confidential 
Business Information or otherwise sensitive or protected information.
    A copy of the application containing a list of the references used 
in this document may be obtained by writing to the address specified 
above, telephoning the contact listed below (see FOR FURTHER 
INFORMATION CONTACT), or visiting the Internet at: https://www.nmfs.noaa.gov/pr/permits/incidental.htm. The National Science 
Foundation (NSF), which is providing funding for the proposed action, 
has prepared a draft Environmental Assessment (EA) titled ``Marine 
Geophysical Survey by the R/V Melville in the Pacific Ocean off Central 
and South America, October-November 2010''. The NSF draft EA 
incorporates an ``Environmental Assessment of a Marine Geophysical 
Survey by the R/V Melville in the Pacific Ocean off Central and South 
America, October-November 2010'', prepared by LGL Limited, 
Environmental Research Associates, on behalf of NSF. These associated 
documents, prepared in compliance with the National Environmental 
Policy Act (NEPA), are also available at the same Internet address. 
Documents cited in this notice may also be viewed, by appointment, 
during regular business hours, at the aforementioned address.

FOR FURTHER INFORMATION CONTACT: Ben Laws or Candace Nachman, Office of 
Protected Resources, NMFS, (301) 713-2289.

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 small numbers 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

[[Page 54096]]

authorization is provided to the public for review.
    Authorization for incidental takings 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 (where 
relevant), and if 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 U.S. can apply for an authorization to 
incidentally take small numbers of marine mammals by 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 the authorization. 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].

Summary of Request

    NMFS received an application on May 28, 2010 from SIO for the 
taking, by harassment, of marine mammals incidental to conducting, in 
collaboration with Texas A&M University and with research funding 
provided by the National Science Foundation, a low-energy marine 
seismic survey. NMFS reviewed SIO's application and identified a number 
of issues requiring further clarification. After addressing comments 
from NMFS, SIO modified its application and submitted a revised 
application on July 14, 2010. NMFS carefully evaluated SIO's 
application, including their analyses, and determined that the 
application is complete and provides sufficient data for NMFS to make 
the necessary preliminary determinations pursuant to the MMPA. The July 
14, 2010 application is the one available for public comment (see 
ADDRESSES) and considered by NMFS for this proposed IHA.
    The proposed survey will occur in the Eastern Tropical Pacific 
Ocean (ETP), encompassing the area from approximately 8[deg] N-12[deg] 
S and 80-91[deg] W, off the coasts of Costa Rica, Panama, Colombia, 
Ecuador, and Peru, in International Waters and within the Exclusive 
Economic Zones (EEZs) of Costa Rica, Panama, Colombia, and Ecuador, and 
is scheduled to occur from October 19-November 14, 2010. Some minor 
deviation from these dates is possible, depending on logistics and 
weather. The survey will use a pair of Generator Injector (GI) airguns, 
each with a discharge volume of 45 in\3\. Seismic airgun operations are 
expected to result in the incidental take, by Level B harassment only, 
of up to 21 species of marine mammals. These species include: Bryde's 
whale; blue whale; sperm whale; humpback whale; Cuvier's beaked whale; 
Blainville's beaked whale; pygmy beaked whale; gingko-toothed beaked 
whale; rough-toothed dolphin; bottlenose dolphin; pantropical spotted 
dolphin; spinner dolphin; striped dolphin; Fraser's dolphin; short-
beaked common dolphin; Risso's dolphin; melon-headed whale; pygmy 
killer whale; false killer whale; killer whale; and short-finned pilot 
whale.

Description of the Specified Activity

    SIO plans to conduct a seismic survey as part of an integrated 
geophysical and geochemical study. In addition to the GI airguns, a 
multibeam echosounder (MBES) and a sub-bottom profiler (SBP) will be 
utilized for research purposes. The planned survey will involve one 
source vessel, the R/V Melville (Melville).
    The purpose of this project is to better understand how marine 
sediments record paleo-oceanographic information. The deposition of 
sediments in the upper 500 m (1640.4 ft) of the sediment column will be 
studied using known seismic horizons in the sediment column to estimate 
rates of deposition downstream from potential sediment sources on the 
topographic highs and to estimate loss from the ridges. The seismic 
survey and associated coring and water sampling will allow comparisons 
of geophysical estimates of the level of erosion from marine ridges and 
highs with geochemical estimates of sediment focusing based upon the 
distribution of Th-230, a particle-reactive isotope produced by the 
decay of dissolved uranium in the water column. In addition, the study 
will examine whether there are sediment sources for Th-230 in slowly-
accumulating sediments.
    The Melville is expected to depart Puntarenas, Costa Rica, on 
October 19, 2010, and spend approximately 15 days conducting seismic 
surveys, 10 days collecting water and core samples, and approximately 2 
days in transit, arriving at Arica, Chile, on November 14, 2010. At 
each of four sites (see Figure 1 of SIO's application), seismic 
operations will be conducted for approximately 2 days, and each water 
sampling and coring station will be occupied for 1-2 days. Some minor 
deviation from these dates is possible, depending on logistics and 
weather.
    The source vessel, the Melville, will deploy a pair of low-energy 
GI airguns as an energy source at a depth of 2 m (each with a discharge 
volume of 45 in\3\), plus either of two towed hydrophone streamers, one 
725 m (2378.6 ft) long with 40 channels, and the other 350 m (1148.3 
ft) long with 16 channels. Hydrophone streamers are towed at adjustable 
depth to afford best reception of returning seismic signals, depending 
upon surface conditions, but are typically towed in at approximately 10 
m. The energy to the GI airgun is compressed air supplied by 
compressors onboard the source vessel. As the GI airgun is towed along 
the survey lines, the receiving systems will receive the returning 
acoustic signals.
    In addition to the GI airguns, an MBES and an SBP will be used 
throughout the cruise, except while at water/core stations, to help 
verify seafloor conditions at possible coring sites and to collect 
additional seafloor bathymetric data. Passive geophysical sensors (a 
gravimeter and a magnetometer) will also be operated continuously 
throughout the entire cruise.
    All potential incidental take, by harassment only, is expected to 
result from the operation of the GI airguns. Take is not expected to 
result from the use of the MBES or SBP, for reasons discussed below, or 
from collision with the vessel because it is a single vessel, moving at 
a relatively slow speed (operational speeds of approximately 11 km/hr 
[6 knots] during seismic acquisition within the survey areas and 15-
18.5 km/hr [8-10 knots] between survey areas and stations), for a 
relatively short period of time (approximately 30 days). It is likely 
that any marine mammal would be able to avoid the vessel.
    The seismic program will consist of approximately 5475 km (3402 mi) 
of

[[Page 54097]]

survey lines, including turns (see Figure 1 of SIO's application). 
Water depths at the seismic survey locations are approximately 1000-
4800 m (3280.8-15,748 ft). The GI airguns will be operated on a small 
grid for approximately 45 hours at each of four sites (see Figure 1 of 
SIO's application) where the 40-channel streamer will be used, and for 
most of the time during transits between the sites, to the first site, 
and after the last site, where the 12-channel streamer will be used. 
There will be additional seismic operations associated with equipment 
testing, startup, and possible line changes or repeat coverage of any 
areas where initial data quality is sub-standard. Those additional 
operations are allowed for in the estimated total line-kilometers given 
above. The Melville is expected to depart Puntarenas, Costa Rica, on 
October 19, 2010 and spend approximately 15 days conducting seismic 
surveys, 10 days collecting water and core samples, and approximately 2 
days in transit, arriving at Arica, Chile, on November 14, 2010.
    All planned geophysical data acquisition activities will be 
conducted by SIO with on-board assistance by the scientists who have 
proposed the study. The Chief Scientist is Dr. Franco Marcantonio of 
Texas A&M University. The vessel will be self-contained, and the crew 
will live aboard the vessel for the entire cruise.

Vessel Specifications

    The Melville has a length of 85 m (278.9 ft), a beam of 14 m (45.9 
ft), and a maximum draft of 5 m (16.4 ft). The ship is powered by two 
1385-hp diesel engines and a 900-hp retracting azimuthing bow thruster. 
Operation speeds of approximately 11 km/hr (5.9 knots) and 15-18.5 km/
hr (8.1-10 knots) will be used during seismic acquisition within the 
survey areas and between the areas and stations, respectively. When not 
towing seismic survey gear, the Melville cruises at 21.7 km/hr (11.7 
knots) and has a maximum speed of 25.9 km/hr (14 knots). The Melville 
will also serve as the platform from which vessel-based protected 
species observers (PSOs) will watch for animals before and during 
airgun operations (discussed later in this document).

Acoustic Source Specifications

(1) Seismic Airguns
    The Melville will tow a pair of 45-in\3\ Sercel GI airguns and a 
streamer containing hydrophones along predetermined lines. Seismic 
pulses will be emitted at intervals of 8-10 s. At speeds of 
approximately 11-18.5 km/hr (5.9-10 knots), the 8-10 s spacing 
corresponds to shot intervals of approximately 25-50 m (82-164 ft).
    The generator chamber of each GI airgun, responsible for 
introducing the sound pulse into the ocean, is 45 in\3\. The larger 
(105-in\3\) injector chamber injects air into the previously-generated 
bubble to maintain its shape and does not introduce more sound into the 
water. The two 45-in\3\ GI airguns will be towed 8 m (26.2 ft) apart 
side by side, 21 m (68.9 ft) behind the Melville, at a depth of 2 m 
(6.6 ft).
    As the GI airgun is towed along the survey line, the towed 
hydrophone array in the streamer receives the reflected signals and 
transfers the data to the on-board processing system. Given the 
relatively short streamer length behind the vessel, the turning rate of 
the vessel while the gear is deployed is much higher than the limit of 
five degrees per minute for a seismic vessel towing a streamer of more 
typical length (greater than l km (0.6 mi)). Thus, the maneuverability 
of the vessel is not limited much during operations.
    The root mean square (rms) received levels that are used as impact 
criteria for marine mammals are not directly comparable to the peak (pk 
or 0-pk) or peak-to-peak (pk-pk) values normally used to characterize 
source levels of airgun arrays. The measurement units used to describe 
airgun sources, peak or peak-to-peak decibels, are always higher than 
the rms decibels referred to in biological literature. A measured 
received level of 160 dB re 1 [mu]Pa (rms) in the far field would 
typically correspond to a peak measurement of approximately 170 dB and 
to a peak-to-peak measurement of approximately 176-178 dB, as measured 
for the same pulse received at the same location (Greene, 1997; 
McCauley et al., 1998, 2000). The precise difference between rms and 
peak or peak-to-peak values depends on the frequency content and 
duration of the pulse, among other factors. However, the rms level is 
always lower than the peak or peak-to-peak level for an airgun-type 
source. The actual received level at any location in the water near the 
GI airguns will not exceed the source level of the strongest individual 
source. In this case, that will be about 224.6 dB re 1 [micro]Pa-m peak 
or 229.8 dB re 1 [micro]Pa-m peak-to-peak. The dominant frequency 
components of the GI airguns are 0-188 Hertz (Hz).
    Received sound levels have been modeled by Lamont-Doherty Earth 
Observatory (L-DEO) for a number of airgun configurations, including 
two 45 in\3\ Nucleus G. Guns, in relation to distance and direction 
from the airgun (see Figure 2 of SIO's application). The model does not 
allow for bottom interactions and is most directly applicable to deep 
water. Based on the modeling, estimates of the maximum distances from 
the GI airguns where sound levels of 190, 180, and 160 dB re 1 [mu]Pa 
(rms) are predicted to be received in deep (>1,000 m (3280.8 ft)) water 
are shown in Table 1 below. Because the model results are for G. Guns, 
which have more energy than GI airguns of the same size, the distances 
in Table 1 overestimate the distances for the 45 in\3\ GI airguns.
(2) Multibeam Echosounder and Sub-Bottom Profiler
    Along with the GI airgun operations, an MBES and a SBP will be 
operated from the source vessel at certain times during the planned 
study to help verify seafloor conditions at possible coring sites and 
to collect additional seafloor bathymetric data.
    The Kongsberg EM 122 MBES operates at 10.5-13 (usually 12) 
kilohertz (kHz) and is hull-mounted on the Melville. The transmitting 
beamwidth is 1[deg] fore-aft and 150[deg] athwartship. The maximum 
source level is 242 dB re 1 [mu]Pa-m (rms). Each ``ping'' consists of 
eight (in water >1000 m deep) or four (<1000 m deep) successive fan-
shaped transmissions, each ensonifying a sector that extends 1[deg] 
fore-aft. Continuous-wave pulses increase from 2 to 15 ms long in water 
depths up to 2600 m (8530.2 ft), and FM chirp pulses up to 100 ms long 
are used in water >2600 m. The successive transmissions span an overall 
cross-track angular extent of about 150[deg], with 2-ms gaps between 
the pulses for successive sectors.
    The Knudsen Engineering Model 320B/R SBP is a dual-frequency 
transceiver designed to operate at 3.5 and/or 12 kHz. It is used in 
conjunction with the MBES to provide data about the sedimentary 
features that occur below the sea floor. The energy from the SBP is 
directed downward via a 3.5-kHz transducer array mounted in the hull of 
the Melville. The maximum power output of the 320B/R is 10 kilowatts 
for the 3.5-kHz section and 2 kilowatts for the 12-kHz section. The 
nominal beamwidth is 80[deg].
    The pulse length for the 3.5-kHz section of the 320B/R is 0.8-24 
ms, controlled by the system operator in regards to water depth and 
reflectivity of the bottom sediments and will usually be 6, 12, or 24 
ms at the water depths at the study sites and in transit from 
Puntarenas and to Arica. The system produces one sound pulse and then 
waits for its return before transmitting again. Thus, the pulse

[[Page 54098]]

interval is directly dependent upon water depth, and in this survey is 
0.8-1.5 s. Using the Sonar Equations and assuming 100 percent 
efficiency in the system (impractical in real world applications), the 
source level for the 320B/R is calculated to be 211 dB re 1 [mu]Pa-m. 
In practice, the system is rarely operated above 80 percent power 
level.
(3) Safety Radii
    NMFS has determined that for acoustic effects, using acoustic 
thresholds in combination with corresponding safety radii is an 
effective way to consistently apply measures to avoid or minimize the 
impacts of an action, and to quantitatively estimate the effects of an 
action. Thresholds are used in two ways: (1) To establish a mitigation 
shut-down or power-down zone, i.e., if an animal enters an area 
calculated to be ensonified above the level of an established 
threshold, a sound source is powered down or shut down; and (2) to 
calculate take, in that a model may be used to calculate the area 
around the sound source that will be ensonified to that level or above, 
then, based on the estimated density of animals and the distance that 
the sound source moves, NMFS can estimate the number of marine mammals 
that may be ``taken.''
    As a matter of past practice and based on the best available 
information at the time regarding the effects of marine sound, NMFS 
estimates that Level A harassment from acoustic sources may occur when 
animals are exposed to levels above 180 dB re 1 [mu]Pa (rms) level for 
cetaceans and 190 dB re 1 [mu]Pa (rms) for pinnipeds. A review of the 
available scientific data using an application of science-based 
extrapolation procedures (Southall et al., 2007) strongly suggests that 
Level A harassment (as well as temporary threshold shift (TTS)) from 
single sound exposure impulse events may occur at much higher levels 
than the levels previously estimated using very limited data. However, 
for purposes of this proposed action, SIO's application sets forth, and 
NMFS is using, the more conservative 180 and 190 dB re 1 [mu]Pa (rms) 
criteria. NMFS also considers 160 dB re 1 [mu]Pa (rms) as the criterion 
for estimating the onset of Level B harassment from acoustic sources 
producing impulse sounds, as in this seismic survey.
    Empirical data concerning the 180- and 160-dB distances have been 
acquired based on measurements during the acoustic verification study 
conducted by L-DEO in the northern Gulf of Mexico from May 27-June 3, 
2003 (Tolstoy et al., 2004). Although the results are limited, the data 
showed that radii around the airguns where the received level would be 
180 dB re 1 [mu]Pa (rms), the safety criterion applicable to cetaceans 
(NMFS 2000), vary with water depth. Similar depth-related variation is 
likely in the 190 dB distances applicable to pinnipeds. Correction 
factors were developed for water depths 100-1000 m and <100 m. The 
proposed survey will occur in depths of approximately 1000-4800 m, so 
the correction factors for shallow water are not relevant here. All of 
the seismic operations will be in depths >1000 m.
    The empirical data indicate that, for deep water (>1000 m), the L-
DEO model tends to overestimate the received sound levels at a given 
distance (Tolstoy et al., 2004). However, to be precautionary pending 
acquisition of additional empirical data, it is proposed that safety 
radii during GI airgun operations in deep water will be values 
predicted by L-DEO's model (see Table 1 in this document). Therefore, 
the assumed 180- and 190-dB radii are 40 m (131.2 ft) and 10 m (32.8 
ft), respectively.

Table 1--Predicted Distances To Which Sound Levels [gteqt]190, 180 and 160 dB re 1 [mu]Pa (rms) Might Be Received From Two 45 in\3\ GI Airguns That Will
                          Be Used During the Seismic Surveys in the Eastern Tropical Pacific Ocean During October-November 2010
                                                [Distances are based on model results provided by L-DEO.]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                        Estimated distances at received levels (m)
              Source and volume                 Tow depth (m)              Water depth          --------------------------------------------------------
                                                                                                       190 dB             180 dB             160 dB
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Two GI airguns, 45 in\3\ each...............                 2   Deep (>1000 m)................                10                 40                400
--------------------------------------------------------------------------------------------------------------------------------------------------------

Description of Marine Mammals in the Area of the Specified Activity

    Forty-three species of marine mammals, including 29 odontocetes, 7 
mysticetes, 6 pinnipeds, and the marine sea otter (Enhydra lutris), are 
known to occur in the ETP. Of these, 23 cetacean species are likely to 
occur in the proposed survey areas in the ETP during October-November 
(see Table 2 in this document), and are considered further here. Three 
of these 23 cetacean species are listed under the Endangered Species 
Act (ESA) as Endangered: The sperm (Physeter macrocephalus), humpback 
(Megaptera novaeangliae), and blue (Balaenoptera musculus) whales.
    Nine cetacean species, although present in the wider ETP, likely 
would not be found in the proposed seismic survey areas because their 
ranges do not extend that far south or north. Pacific white-sided 
dolphins (Lagenorhynchus obliquidens) and Baird's beaked whales 
(Berardius bairdii) are seen very occasionally in the northernmost 
portions of the ETP (Ferguson and Barlow, 2001). Long-beaked common 
dolphins (Delphinus capensis) are known to occur in the northernmost 
areas of the ETP off Baja California, Mexico, and off the coast of Peru 
(Heyning and Perrin, 1994). Southern right whales (Eubalaena australis) 
are seen on rare occasions off the coasts of Peru and Chile (Aguayo et 
al., 1992; Santillan et al., 2004). Gray's beaked whales (Mesoplodon 
grayi) are distributed in the southernmost portions of the ETP and off 
the coast of southern Peru (Culik, 2010). Dusky dolphins 
(Lagenorhynchus obscurus), southern right whale dolphins (Lissodelphis 
peronii), Burmeister's porpoises (Phocoena spinipinnis), and long-
finned pilot whales (Globicephala melas) also occur near the Peruvian 
coast (Leatherwood et al., 1991; Van Waerebeek et al., 1991; Brownell 
and Clapham, 1999; Olson and Reilly, 2002). These nine species are not 
addressed in detail in SIO's application and are not considered further 
in this Notice of Proposed IHA.
    Sei (Balaenoptera borealis) and fin (B. physalus) whales, listed as 
Endangered under the ESA, are known from the ETP but are considered 
very rare in the proposed survey area. Sei whales may have been sighted 
during surveys in the ETP (Wade and Gerrodette, 1993; Kinzey et al., 
1999, 2000, 2001); however, it is difficult to distinguish sei whales 
from Bryde's whales (B. edeni) at sea. Because sei whales generally 
have a more northerly and temperate distribution (Leatherwood et al., 
1988), Wade and Gerrodette (1993) classified

[[Page 54099]]

any tentative sei whale observations in the ETP as Bryde's whale 
sightings. Sei whales may also have been sighted near the Galapagos 
Islands (Clarke, 1962); although, Clarke and Aguayo (1965) suggested 
that those sightings could have been Bryde's whales. Although the 
occurrence of sei whales is documented off Costa Rica (Rodriguez-
Herrera et al., 2002), the reliability of the identification is 
uncertain. Neither Ferguson and Barlow (2001) or Jackson et al. (2008) 
positively identified sei whales in or near the proposed project area 
during surveys conducted during July-December. Similarly, Rasmussen et 
al. (2004) did not report sei whales in 8 years of surveys off Costa 
Rica or Panama. No sei whales were detected during L-DEO seismic 
surveys off Costa Rica or Nicaragua in November-December 2004 or 
February-March 2008 (Holst et al., 2005b; Holst and Smultea, 2008), in 
the Hess Deep approximately 1100 km (683.5 mi) west of the Galapagos 
Islands in July 2003 (Smultea and Holst, 2003), or 1600-1950 km (994.2-
1211.7 mi) west of the proposed survey area in April-August 2008 
(Hauser et al., 2008).
    No confirmed fin whale sightings were made in the proposed study 
area during 10 years of survey effort in July-December by Ferguson and 
Barlow (2001) or by Jackson et al. (2008) during July-December surveys 
in 2006. Despite >30 years of NMFS and other surveys, as well as 
stranding records from the Pacific coast of Costa Rica, there have been 
no confirmed records of fin whales (May-Collado et al., 2005). A 
possible sighting of a fin whale in this region occurred off the Osa 
Peninsula in 1997; however, the sighting was not confirmed (May-Collado 
et al., 2005), although Rodriguez-Herrera et al. (2002) list the fin 
whale as having been documented off Costa Rica. No fin whales were 
detected during L-DEO seismic surveys off Costa Rica or Nicaragua in 
November-December 2004 or February-March 2008 (Holst et al., 2005b; 
Holst and Smultea, 2008), in the Hess Deep approximately 1100 km (683.5 
mi) west of the Galapagos Islands in July 2003 (Smultea and Holst, 
2003), or 1600-1950 km (994.2-1211.7 mi) west of the proposed survey 
area in April-August 2008 (Hauser et al., 2008). Sei and fin whales are 
not considered further in this document.
    The general distribution of minke whales (Balaenoptera 
acutorostrata) includes the offshore waters of the study area (Reeves 
et al., 2002). However, minke whales are likely to be rare in the 
survey area. This species has been found off the coast of Costa Rica on 
occasion (Rodriguez-Herrera et al., 2002). No minke whales were found 
in the proposed project region during July-December surveys during 
1986-1996 by Ferguson and Barlow (2001) or in 2006 by Jackson et al. 
(2008). Rasmussen et al. (2004) did not report seeing any minke whales 
in 8 years of surveys (1996-2003) off Costa Rica or in 2001-2003 off 
Panama. May-Collado et al. (2005) also did not report any minkes based 
on compiled sightings off Costa Rica during 1979-2001, nor have minkes 
been reported among compiled strandings off Costa Rica (Rodriguez-
Fonseca and Cubero-Pardo, 2001). Minke whales are unlikely to occur in 
the planned survey areas and are not considered further in this 
document.
    Longman's beaked whale (Indopacetus pacificus), also known as the 
tropical bottlenose whale, is considered rare in the ETP. Although 
widespread throughout the tropical Pacific, the species is considered 
rare because of a scarcity of sightings despite a great deal of survey 
effort (Pitman et al., 1999). In the ETP, most tropical bottlenose 
whale sightings have been made between 3-10[deg] N (Pitman et al., 
1999). Kinzey et al. (2001) reported one sighting of I. pacificus in 
the ETP at about 135[deg] W. Jackson et al. (2008) also reported I. 
pacificus in the ETP well to the west of the proposed study area. No 
Longman's beaked whales were reported by May-Collado et al. (2005) 
based on compiled sightings off Costa Rica from 1979-2001. The species 
is very rare in the study area and is not considered further in this 
document.
    Dwarf (Kogia sima) and pygmy (K. breviceps) sperm whales may occur 
in the proposed survey area, although dwarf sperm whales are likely to 
be very rare and pygmy sperm whales are likely to be rare. No Kogia sp. 
were detected during L-DEO seismic surveys off Costa Rica and Nicaragua 
in November-December 2004 (Holst et al., 2005b) or in the Hess Deep 
approximately 1100 km (683.5 mi) west of the Galapagos Islands in July 
2003 (Smultea and Holst, 2003). One sighting of a dwarf sperm whale and 
one sighting of two pygmy sperm whales were observed off the coast of 
Costa Rica in waters approximately 2000 m (6561.7 ft) and 3500 m 
(11482.9 ft) deep, respectively, during an L-DEO seismic survey off 
Costa Rica and Nicaragua in February-March 2008 (Holst and Smultea, 
2008), and one unidentified Kogia sp. was sighted during L-DEO seismic 
surveys 1600-1950 km (994.2-1211.7 mi) west of the proposed survey area 
in April-August 2008 (Hauser et al., 2008). Due to the rarity of these 
species, no take has been requested and none will be authorized.
    Six species of pinnipeds are known to occur in the ETP: The 
Guadalupe fur seal (Arctocephalus townsendi), California sea lion 
(Zalophus californianus), Galapagos sea lion (Z. wollebaeki), Galapagos 
fur seal (A. galapagoensis), southern sea lion (Otaria flavescens), and 
the South American fur seal (A. australis). Ranges of the first two are 
substantially north of the proposed seismic survey areas, and the last 
four species are not expected to occur in the offshore waters of the 
study areas. The marine sea otter, which is managed by the U.S. Fish 
and Wildlife Service, is a coastal species and does not occur in 
offshore waters. Pinnipeds are highly unlikely to occur in the survey 
area and are not considered in further detail here.
    The ETP is a biologically productive area that supports a variety 
of cetacean species (Au and Perryman, 1985). Several studies of marine 
mammal distribution and abundance have been conducted in the wider ETP. 
The most extensive regional distribution and abundance data that 
encompass the study area come primarily from multi-year vessel surveys 
conducted in the wider ETP by the NMFS Southwest Fisheries Science 
Center (SWFSC). Information on the distribution of cetaceans inhabiting 
the ETP has been summarized in several studies (Polacheck, 1987; Wade 
and Gerrodette, 1993; Ferguson and Barlow, 2001; Gerrodette et al., 
2008). However, for some species, abundance in the proposed seismic 
survey area could be quite different from that of the wider ETP, 
depending on local oceanographic variability.
    In addition, procedures used during the various surveys that are 
cited have differed somewhat, and those differences could affect the 
results. For example, Ferguson and Barlow (2001) calculated cetacean 
densities in the ETP based on summer/fall research surveys in 1986-
1996. Their densities are corrected for both changes in detectability 
of species with distance from the survey track line and for perception 
and availability bias. Gerrodette et al. (2008) calculated dolphin 
abundance in the ETP based on summer/fall research surveys in 1986-
1990, 1998-2000, 2003, and 2006. Their estimates are corrected for the 
former but not the latter.
    Additional sighting records are available from recent surveys in 
the ETP. Jackson et al. (2008) described cetacean sightings data 
collected during a survey from July 28-December 7, 2006. The survey 
area extended from 30[deg] N-18[deg] S from the coastline to 153[deg] 
W, overlapping with the proposed

[[Page 54100]]

seismic survey area. Rasmussen et al. (2004) and Calambokidis et al. 
(2010) described cetacean sightings resulting from humpback whale 
surveys off Costa Rica and surrounding waters from January to March in 
1996-2003 and 2010. Recent at-sea monitoring for L-DEO in the ETP also 
provided sighting records for cetaceans during seismic programs. 
Seismic monitoring programs took place at the Hess Deep in July 2003, 
approximately 1100 km (683.5 mi) west of the Galapagos Islands (Smultea 
and Holst, 2003); from Costa Rica to El Salvador in November-December 
2004, mainly within approximately 100 km (62.1 mi) of the coast in 
water depths extending to 5000 m (16,404.2 ft) (Holst et al., 2005b); 
from Costa Rica to Nicaragua in March-April 2008, up to approximately 
200 km (124.3 mi) from the coast in water depths extending to 5000 m 
(Holst and Smultea, 2008); and approximately 1600-1900 km (994.2-
1,180.6 mi) west of the study area in April-August 2008 (Hauser et al., 
2008).
    Information on the occurrence, distribution, population size, and 
conservation status for each of the 23 cetacean species that may occur 
in the proposed project area during October-November is presented in 
Table 2 in this document. The five species of marine mammals expected 
to be most common in the waters of the project area, all delphinids, 
include the short beaked common dolphin (Delphinus delphis), 
pantropical spotted dolphin (Stenella attenuata), bottlenose dolphin 
(Tursiops truncatus), Risso's dolphin (Grampus griseus), and short-
finned pilot whale (Globicephala macrorhynchus). Additional information 
regarding the abundance and distribution, population status, and life 
history and behavior of these species expected to be found in the 
project area and how the estimated densities were calculated may be 
found in SIO's application. NMFS has reviewed these data and determined 
them to be the best available scientific information for the purposes 
of the proposed IHA. Please refer to the application for that 
information (see ADDRESSES). Additional information can also be found 
in the NMFS Stock Assessment Report (SAR). The Pacific 2009 SAR is 
available at: https://www.nmfs.noaa.gov/pr/pdfs/sars/po2009.pdf.

     Table 2--The Occurrence, Habitat, Regional Abundance, Conservation Status, and Best and Maximum Density
   Estimates for Marine Mammals in or Near the Proposed Low-Energy Seismic Survey Area in the Eastern Tropical
   Pacific Ocean. Cetacean Densities Are Based on NMFS SWFSC Ship Transect Surveys Conducted in 1986-2006 From
   Predictive Modeling (Barlow et al. 2009; Read et al. 2009) or in 1986-1996 From Ferguson and Barlow (2003)
                       [See text and Tables 2-4 in SIO's application for further detail.]
----------------------------------------------------------------------------------------------------------------
                                Occurrence in                        Regional                Density
           Species               survey area        Habitat      population size   ESA \2\    (best)    Density
                                during Oct-Nov                         \1\                     \3\     (max) \4\
----------------------------------------------------------------------------------------------------------------
Mysticetes:
    Bryde's Whale,             Uncommon.......  Pelagic and      13,000 \5\.....  NL......       0.53       1.15
     (Balaenoptera edeni).                       coastal.
    Blue whale, (Balaenoptera  Uncommon.......  Pelagic and      1415 \6\.......  EN......       0.13       0.23
     musculus).                                  coastal.
    Humpback whale,            Uncommon.......  Mainly           NE Pacific 1392  EN......   \15\ 0.1   \15\ 0.2
     (Megaptera novaeangliae).                   nearshore        \13\; SE
                                                 waters and       Pacific 2900
                                                 banks.           \14\.
Odontocetes:
    Sperm whale, (Physeter     Common.........  Usually deep     26,053 \7\.....  EN......       3.95      15.20
     macrocephalus).                             pelagic, steep
                                                 topography.
    Pygmy sperm whale, (Kogia  Rare...........  Deep waters off  NA \8\.........  NL......  \16\ 0.01  \16\ 0.02
     breviceps).                                 shelf.
    Dwarf sperm whale, (Kogia  Very rare......  Deep waters off  11,200 \9\.....  NL......  \16\ 0.01  \16\ 0.02
     sima).                                      shelf.
    Cuvier's beaked whale,     Common.........  Slope and        20,000 \6\.....  NL......       1.83       3.70
     (Ziphius cavirostris).                      pelagic.
    Blainville's beaked        Uncommon.......  Pelagic........  25,300 \10\....  NL......  \17\ 0.21  \17\ 0.37
     whale, (Mesoplodon
     densirostris).
    Pygmy beaked whale,        Uncommon.......  Pelagic........  25,300 \10\....  NL......  \17\ 0.21  \17\ 0.37
     (Mesoplodon peruvianus).
    Gingko-toothed beaked      Very rare......  Pelagic........  25,300 \10\....  NL......  \17\ 0.21  \17\ 0.37
     whale, (Mesoplodon
     stejnegeri).
    Bottlenose dolphin,        Very common....  Coastal, shelf,  335,834........  NL......      15.14      23.09
     (Tursiops truncatus).                       pelagic.
    Rough-toothed dolphin,     Common.........  Mainly pelagic.  107,633........  NL......       1.60       2.34
     (Steno bredanensis).
    Short-beaked common        Very common....  Shelf, pelagic,  3,127,203......  NL......     143.21     242.80
     dolphin, (Delphinus                         high relief.
     delphis).
    Pantropical spotted        Very common....  Coastal and      857,884........  NL......      12.43      22.53
     dolphin, (Stenella                          pelagic.
     attenuata).
    Risso's dolphin, (Grampus  Very common....  Shelf, slope,    110,457........  NL......      10.21      37.40
     griseus).                                   seamounts.
    Spinner dolphin,           Very common....  Coastal and      1,797,716......  NL......       3.81       5.74
     (Stenella longirostris).                    pelagic.
    Striped dolphin,           Very common....  Off continental  964,362........  NL......      35.23      53.67
     (Stenella coeruleoalba).                    shelf.
    Fraser's dolphin,          Common.........  Pelagic........  289,300 \6\....  NL......       1.03       5.60
     (Lagenodelphis hosei).
    Melon-headed whale,        Common.........  Pelagic........  45,400 \6\.....  NL......       2.80       9.30
     (Peponocephala electra).
    Pygmy killer whale,        Uncommon.......  Pelagic........  38,900 \6\.....  NL......       0.60       1.80
     (Feresa attenuata).
    False killer whale,        Uncommon.......  Pelagic........  39,800 \6\.....  NL......       0.39       2.10
     (Pseudorca crassidens).
    Killer whale, (Orcinus     Uncommon.......  Widely           8,500 \11\.....  NL......       0.85       4.00
     orca).                                      distributed.

[[Page 54101]]

 
    Short-finned pilot whale,  Common.........  Mostly pelagic,  589,315 \12\...  NL......       6.29      11.74
     (Globicephala                               high-relief.
     macrorhynchus).
----------------------------------------------------------------------------------------------------------------
NA--Data not available or species status was not assessed. For density estimates, NA indicates that estimates
  would be lower than the lowest estimate in this table.
\1\ Abundance from Gerrodette et al. (2008) unless otherwise stated.
\2\ U.S. Endangered Species Act: EN = Endangered, T = Threatened, NL = Not listed.
\3\ Best density (/1000km\2\) estimate as listed in Table 3 of the application. Cetecean densities are
  based on NMFS SWFSC ship transect surveys conducted in 1986-2006 from predictive modeling (Barlow et al. 2009;
  Read et al. 2009) or in 1986-1996 from Ferguson and Barlow (2003).
\4\ Maximum density (/1000km\2\) estimate as listed in Table 3 of the application.
\5\ This estimate is mainly for Balaenoptera edeni but may include some B. borealis.
\6\ ETP (Wade and Gerrodette 1993).
\7\ Eastern temperate North Pacific (Whitehead 2002).
\8\ California/Oregon/Washington (Carretta et al. 2010).
\9\ This abundance estimate is mostly for Kogia sima but may also include some K. breviceps. Density estimates
  for Kogia spp. combined.
\10\ Estimates for population size and for density include all species of the genus Mesoplodon in the ETP
  (Ferguson and Barlow 2001).
\11\ ETP (Ford 2002).
\12\ This estimate is for Globicephala macrorhynchus and G. melas in the ETP (Gerrodette and Forcada 2002).
\13\ U.S. west coast (Carretta et al. 2010).
\14\ Southeast Pacific; Felix et al. (2005).
\15\ Approximate estimates.
\16\ Density estimates are combined for pygmy and dwarf sperm whales.
\17\ Density estimates are combined for species of the genus Mesoplodon.

Marine Mammal Hearing

    The primary effect on marine mammals anticipated from the specified 
activities will result from exposure of animals to underwater sound. 
Exposure to sound can affect marine mammal hearing. When considering 
the influence of various kinds of sound on the marine environment, it 
is necessary to understand that different kinds of marine life are 
sensitive to different frequencies of sound. Based on available 
behavioral data, audiograms derived using auditory evoked potential 
techniques, anatomical modeling, and other data, Southall et al. (2007) 
designate ``functional hearing groups'' for marine mammals and estimate 
the lower and upper frequencies of functional hearing of the groups. 
The functional groups and the associated frequencies are indicated 
below (though animals are less sensitive to sounds at the outer edge of 
their functional range and most sensitive to sounds of frequencies 
within a smaller range somewhere in the middle of their functional 
hearing range):
     Low frequency cetaceans (13 species of mysticetes): 
Functional hearing is estimated to occur between approximately 7 Hz and 
22 kHz;
     Mid-frequency cetaceans (32 species of dolphins, six 
species of larger toothed whales, and 19 species of beaked and 
bottlenose whales): Functional hearing is estimated to occur between 
approximately 150 Hz and 160 kHz;
     High frequency cetaceans (six species of true porpoises, 
four species of river dolphins, two members of the genus Kogia, and 
four dolphin species of the genus Cephalorhynchus): Functional hearing 
is estimated to occur between approximately 200 Hz and 180 kHz; and
     Pinnipeds in water: Functional hearing is estimated to 
occur between approximately 75 Hz and 75 kHz, with the greatest 
sensitivity between approximately 700 Hz and 20 kHz.
    As mentioned previously in this document, 21 cetacean species are 
likely to occur in the proposed survey area. Of the 21 species likely 
to occur in SIO's project area, two are classified as low frequency 
cetaceans (Bryde's, humpback, and blue whales) and 18 are classified as 
mid-frequency cetaceans (sperm, Cuvier's beaked, Blainville's beaked, 
pygmy beaked, gingko-toothed beaked, melon-headed, pygmy killer, false 
killer, killer, and short-finned pilot whales and rough-toothed, 
bottlenose, pantropical spotted, spinner, striped, Fraser's, short-
beaked common, and Risso's dolphins) (Southall et al., 2007).

Potential Effects of the Specified Activity on Marine Mammals

Potential Effects of Airguns

    The effects of sounds from airguns might result in one or more of 
the following: Tolerance, masking of natural sounds, behavioral 
disturbances, temporary or permanent hearing impairment, and non-
auditory physical or physiological effects (Richardson et al., 1995; 
Gordon et al., 2004; Nowacek et al., 2007; Southall et al., 2007). 
Permanent hearing impairment, or PTS, in the unlikely event that it 
occurred, would constitute injury, but temporary threshold shift (TTS) 
is not an injury (Southall et al., 2007). It is unlikely that the 
project would result in any cases of temporary or especially permanent 
hearing impairment or any significant non-auditory physical or 
physiological effects for reasons discussed later in this document. 
Some behavioral disturbance is expected, but it is expected that this 
would be localized and short-term because of the short amount of time 
that would be spent at any particular site within the survey area 
(approximately two days of seismic data acquisition at any one site).
(1) Tolerance
    Numerous studies have shown that pulsed sounds from airguns are 
often readily detectable in the water at

[[Page 54102]]

distances of many kilometers. For a brief summary of the 
characteristics of airgun pulses, see Appendix A(3) of the supporting 
EA (see ADDRESSES). However, it should be noted that most of the 
measurements are for airguns that would be detectable considerably 
farther away than the GI airgun planned for use in the present project.
    Several studies have shown that marine mammals at distances more 
than a few kilometers from operating seismic vessels often show no 
apparent response; see Appendix A(5) of the EA. That is often true even 
in cases when the pulsed sounds must be readily audible to the animals 
based on measured received levels and the hearing sensitivity of the 
mammal group. Although various baleen whales, toothed whales, and (less 
frequently) pinnipeds have been shown to react behaviorally to airgun 
pulses under some conditions, at other times, mammals of all three 
types have shown no overt reactions. In general, pinnipeds usually seem 
to be more tolerant of exposure to airgun pulses than are cetaceans, 
with the relative responsiveness of baleen and toothed whales being 
variable. Given the relatively small and low-energy GI airgun source 
planned for use in this project, mammals are expected to tolerate being 
closer to this source than would be the case for a larger airgun source 
typical of most seismic surveys.
(2) Masking
    Obscuring of sounds of interest by interfering sounds, generally at 
similar frequencies, is known as masking. Masking effects of pulsed 
sounds (even from large arrays of airguns, much larger than that 
proposed for use in this survey) on marine mammal calls and other 
natural sounds are expected to be limited, although there are few 
specific data of relevance. Because of the intermittent nature and low 
duty cycle of seismic pulses, animals can emit and receive sounds in 
the relatively quiet intervals between pulses. However, in some 
situations, multi-path arrivals and reverberation cause airgun sound to 
arrive for much or all of the interval between pulses (Simard et al., 
2005; Clark and Gagnon, 2006), which could mask calls. Whale calls 
often can be heard between the seismic pulses (Richardson et al., 1986; 
McDonald et al., 1995; Greene et al., 1999a,b; Nieukirk et al., 2004; 
Smultea et al., 2004; Holst et al., 2005a,b, 2006; Dunn and Hernandez, 
2009), and certain baleen and toothed whales are known to continue 
calling in the presence of seismic pulses. However, Clark and Gagnon 
(2006) reported that fin whales in the northeast Pacific Ocean went 
silent for an extended period starting soon after the onset of a 
seismic survey in the area. Similarly, there has been one report that 
sperm whales ceased calling when exposed to pulses from a very distant 
seismic ship (Bowles et al., 1994). However, more recent studies found 
that sperm whales continued calling in the presence of seismic pulses 
(Madsen et al., 2002; Tyack et al., 2003; Smultea et al., 2004; Holst 
et al., 2006; Jochens et al., 2008). Given the small source planned for 
use during the proposed survey, there is even less potential for 
masking of baleen or sperm whale calls during the present study than in 
most seismic surveys. Masking effects of seismic pulses are expected to 
be negligible in the case of small odontocetes, given the intermittent 
nature of seismic pulses. Dolphins and porpoises commonly are heard 
calling while airguns are operating (Gordon et al., 2004; Smultea et 
al., 2004; Holst et al., 2005a,b; Potter et al., 2007). The sounds 
important to small odontocetes are predominantly at much higher 
frequencies than are the dominant components of airgun sounds, thus 
limiting the potential for masking. In general, masking effects of 
seismic pulses are expected to be minor, given the normally 
intermittent nature of seismic pulses. Masking effects on marine 
mammals are discussed further in Appendix A(4) of the EA.
(3) Disturbance Reactions
    Disturbance includes a variety of effects, including subtle changes 
in behavior, more conspicuous changes in activities, and displacement. 
Reactions to sound, if any, depend on species, state of maturity, 
experience, current activity, reproductive state, time of day, and many 
other factors (Richardson et al., 1995; Wartzok et al., 2004; Southall 
et al., 2007; Weilgart, 2007). If a marine mammal responds to an 
underwater sound by changing its behavior or moving a small distance, 
the response may or may not rise to the level of ``taking'', or affect 
the stock or the species as a whole. However, if a sound source 
displaces marine mammals from an important feeding or breeding area for 
a prolonged period, impacts on animals or on the stock or species could 
potentially be significant (Lusseau and Bejder, 2007; Weilgart, 2007). 
Given the many uncertainties in predicting the quantity and types of 
impacts of noise on marine mammals, it is common practice to estimate 
how many mammals are likely to be present within a particular distance 
of a given activity, or exposed to a particular level of sound. This 
practice potentially overestimates the numbers of marine mammals that 
are affected in some biologically-important manner.
    The sound exposure thresholds that are used to estimate how many 
marine mammals might be harassed by a seismic survey are based on 
behavioral observations during studies of several species. However, 
information is lacking for many species. Detailed studies have been 
done on humpback, gray (Eschrichtius robustus), bowhead (Balaena 
mysticetus), and sperm whales, and on ringed seals (Phoca hispida). 
Less detailed data are available for some other species of baleen 
whales, small toothed whales, and sea otters, but for many species 
there are no data on responses to marine seismic surveys. Most of those 
studies have concerned reactions to much larger airgun sources than 
planned for use in the proposed SIO project. Thus, effects are expected 
to be limited to considerably smaller distances and shorter periods of 
exposure in the present project than in most of the previous work 
concerning marine mammal reactions to airguns.
    Baleen Whales--Baleen whales generally tend to avoid operating 
airguns, but avoidance radii are quite variable. Whales are often 
reported to show no overt reactions to pulses from large arrays of 
airguns at distances beyond a few kilometers, even though the airgun 
pulses remain well above ambient noise levels out to much longer 
distances. However, as reviewed in Appendix A(5) of the EA, baleen 
whales exposed to strong noise pulses from airguns often react by 
deviating from their normal migration route (Richardson et al., 1999) 
and/or interrupting their feeding activities and moving away from the 
sound source. In the cases of migrating gray and bowhead whales, the 
observed changes in behavior appeared to be of little or no biological 
consequence to the animals. They simply avoided the sound source by 
displacing their migration route to varying degrees, but within the 
natural boundaries of the migration corridors (Schick and Urban, 2000; 
Richardson et al., 1999; Malme et al., 1983).
    Studies of gray, bowhead, and humpback whales have shown that 
seismic pulses with received levels of pulses in the 160-170 dB re 1 
[mu]Pa (rms) range seem to cause obvious avoidance behavior in a 
substantial fraction of the animals exposed (Richardson et al., 1995). 
In many areas, seismic pulses from large arrays of airguns diminish to 
those levels at distances ranging from 4.5-14.5 km (2.8-9 mi) from the 
source. A substantial proportion of the baleen whales within those 
distances may show avoidance or other strong

[[Page 54103]]

disturbance reactions to the airgun array. Subtle behavioral changes 
sometimes become evident at somewhat lower received levels, and studies 
summarized in Appendix A(5) of the EA have shown that some species of 
baleen whales, notably bowhead and humpback whales, at times show 
strong avoidance at received levels lower than 160-170 dB re 1 [mu]Pa 
(rms). Reaction distances would be considerably smaller during the 
proposed project, for which the 160 dB radius is predicted to be 400 m 
(1312.3 ft) (see Table 1 in this document), as compared with several 
kilometers when a large array of airguns is operating.
    Responses of humpback whales to seismic surveys have been studied 
during migration, on summer feeding grounds, and on Angolan winter 
breeding grounds; there has also been discussion of effects on the 
Brazilian wintering grounds. McCauley et al. (1998, 2000a) studied the 
responses of humpback whales off Western Australia to a full-scale 
seismic survey with a 16-airgun, 2678-in \3\ array, and to a single 20-
in \3\ airgun with a source level of 227 dB re 1 [mu]Pa-m peak-to-peak. 
McCauley et al. (1998) documented that initial avoidance reactions 
began at 5-8 km (3.1-5 mi) from the array, and that those reactions 
kept most pods approximately 3-4 km (1.9-2.5 mi) from the operating 
seismic boat. McCauley et al. (2000a) noted localized displacement 
during migration of 4-5 km (2.5-3.1 mi) by traveling pods and 7-12 km 
(4.3-7.5 mi) by cow-calf pairs. Avoidance distances with respect to the 
single airgun were smaller but consistent with the results from the 
full array in terms of received sound levels. The mean received level 
for initial avoidance reactions to an approaching airgun was 140 dB re 
1 [mu]Pa (rms) for humpback whale pods containing females. The standoff 
range, i.e., the mean closest point of approach of the whales to the 
airgun, corresponded to a received level of 143 dB re 1 [mu]Pa (rms). 
The initial avoidance response generally occurred at distances of 5-8 
km (3.1-5.0 mi) from the airgun array and 2 km (1.2 mi) from the single 
airgun. However, some individual humpback whales, especially males, 
approached within distances of 100-400 m (328.1-1312.3 ft), where the 
maximum received level was 179 dB re 1 [mu]Pa (rms).
    Humpback whales on their summer feeding grounds in southeast Alaska 
did not exhibit persistent avoidance when exposed to seismic pulses 
from a 100-in \3\ airgun (Malme et al., 1985). Some humpbacks seemed 
``startled'' at received levels of 150-169 dB re 1 [mu]Pa on an 
(approximate) rms basis. Malme et al. (1985) concluded that there was 
no clear evidence of avoidance, despite the possibility of subtle 
effects, at received levels up to 172 re 1 [mu]Pa on an (approximate) 
rms basis.
    It has been suggested that South Atlantic humpback whales wintering 
off Brazil may be displaced or even strand upon exposure to seismic 
surveys (Engel et al., 2004). The evidence for this was circumstantial 
and subject to alternative explanations (IAGC 2004). Also, the evidence 
was not consistent with subsequent results from the same area of Brazil 
(Parente et al., 2006), or with results from direct studies of humpback 
whales exposed to seismic surveys in other areas and seasons. After 
allowance for data from subsequent years, there was ``no observable 
direct correlation'' between strandings and seismic surveys (IWC 2007).
    Studies of bowhead whales show that their responsiveness can be 
quite variable depending on the activity (e.g., migrating vs. feeding). 
Bowhead whales migrating west across the Alaskan Beaufort Sea in 
autumn, in particular, are unusually responsive, with substantial 
avoidance occurring out to distances of 20-30 km (12.4-18.6 mi) from a 
medium-sized airgun source at received sound levels of around 120-130 
dB re 1 [mu]Pa (rms) (Miller et al., 1999; Richardson et al., 1999; see 
also Appendix A (5) of the EA). However, more recent research on 
bowhead whales (Miller et al., 2005; Harris et al., 2007) corroborates 
earlier evidence that, during the summer feeding season, bowheads are 
not as sensitive to seismic sources. Nonetheless, subtle but 
statistically significant changes in surfacing-respiration-dive cycles 
were evident upon statistical analysis (Richardson et al., 1986). In 
summer, bowheads typically begin to show avoidance reactions at 
received levels of about 152-178 dB re 1 [mu]Pa (rms) (Richardson et 
al., 1986, 1995; Ljungblad et al., 1988; Miller et al., 2005).
    Reactions of migrating and feeding (but not wintering) gray whales 
to seismic surveys have been studied. Malme et al. (1986, 1988) studied 
the responses of feeding Eastern Pacific gray whales to pulses from a 
single 100-in\3\ airgun off St. Lawrence Island in the northern Bering 
Sea. They estimated, based on small sample sizes, that 50 percent of 
feeding gray whales ceased feeding at an average received pressure 
level of 173 dB re 1 [mu]Pa on an (approximate) rms basis and that 10 
percent of feeding whales interrupted feeding at received levels of 163 
dB re 1 [mu]Pa (rms). Those findings were generally consistent with the 
results of experiments conducted on larger numbers of gray whales that 
were migrating along the California coast (Malme et al., 1984; Malme 
and Miles, 1985) and with observations of Western Pacific gray whales 
feeding off Sakhalin Island, Russia, when a seismic survey was underway 
just offshore of their feeding area (Wursig et al., 1999; Gailey et 
al., 2007; Johnson et al., 2007; Yazvenko et al., 2007a,b), along with 
data on gray whales off British Columbia (Bain and Williams, 2006). 
Gray whales typically show no conspicuous responses to airgun pulses 
with received levels up to 150 to 160 dB re 1 [mu]Pa (rms), but are 
increasingly likely to show avoidance as received levels increase above 
that range. While neither bowhead nor gray whales are present in the 
study area, these studies can be used to draw general inference about 
the potential reactions of other baleen whales to underwater sound.
    Various species of the genus Balaenoptera (e.g., blue, sei, fin, 
Bryde's, and minke whales) have occasionally been reported in areas 
ensonified by airgun pulses (Stone, 2003; MacLean and Haley, 2004; 
Stone and Tasker, 2006), and calls from blue and fin whales have been 
localized in areas with airgun operations (McDonald et al., 1995; Dunn 
and Hernandez, 2009). Sightings by observers on seismic vessels off the 
United Kingdom from 1997-2000 suggest that, at times of good 
sightability, sighting rates for mysticetes (mainly fin and sei whales) 
were similar when large arrays of airguns were shooting and not 
shooting (Stone, 2003; Stone and Tasker, 2006). However, these whales 
tended to exhibit localized avoidance, remaining significantly further 
(on average) from the airgun array during seismic operations compared 
with non-seismic periods (Stone and Tasker, 2006). In a study off Nova 
Scotia, Moulton and Miller (2005) found little difference in sighting 
rates (after accounting for water depth) and initial sighting distances 
of balaenopterid whales when airguns were operating vs. silent. 
However, there were indications that these whales were more likely to 
be moving away when seen during airgun operations. Similarly, ship-
based monitoring studies of blue, fin, sei, and minke whales offshore 
of Newfoundland (Orphan Basin and Laurentian Sub-basin) found no more 
than small differences in sighting rates and swim direction during 
seismic vs. non-seismic periods (Moulton et al., 2005, 2006a,b).
    Data on short-term reactions, or lack thereof, by cetaceans to 
impulsive noises do not necessarily provide information about long-term 
effects. It is

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not known whether impulsive noises affect reproductive rate or 
distribution and habitat use in subsequent days or years. However, gray 
whales continued to migrate annually along the west coast of North 
America with substantial increases in the population over recent years, 
despite intermittent seismic exploration (and much ship traffic) in 
that area for decades (see Appendix A in Malme et al., 1984; Richardson 
et al., 1995; Angliss and Allen, 2009). The Western Pacific gray whale 
population did not seem affected by a seismic survey in its feeding 
ground during a prior year (Johnson et al., 2007). Bowhead whales have 
continued to travel to the eastern Beaufort Sea each summer, and their 
numbers have increased notably (3.4 percent annually for nearly a 
decade), despite seismic exploration in their summer and autumn range 
for many years (Richardson et al., 1987; Angliss and Allen 2009). In 
any event, brief exposures to sound pulses from the proposed airgun 
source are highly unlikely to result in prolonged effects.
    Toothed Whales--Little systematic information is available about 
reactions of toothed whales to noise pulses. Few studies similar to the 
more extensive baleen whale/seismic pulse work summarized above have 
been reported for toothed whales. However, systematic studies on sperm 
whales have been done (Gordon et al., 2006; Madsen et al., 2006; Winsor 
and Mate, 2006; Jochens et al., 2008; Miller et al., 2009), and there 
is an increasing amount of information about responses of various 
odontocetes to seismic surveys based on monitoring studies (Stone 2003; 
Smultea et al., 2004; Moulton and Miller, 2005; Bain and Williams, 
2006; Holst et al., 2006; Stone and Tasker, 2006; Potter et al., 2007; 
Hauser et al., 2008; Holst and Smultea, 2008; Weir, 2008; Barkaszi et 
al., 2009; Richardson et al., 2009).
    Seismic operators and PSOs on seismic vessels regularly see 
dolphins and other small toothed whales near operating airgun arrays, 
but, in general, there seems to be a tendency for most delphinids to 
show some avoidance of operating seismic vessels (Goold, 1996a,b,c; 
Calambokidis and Osmek, 1998; Stone, 2003; Moulton and Miller, 2005; 
Holst et al., 2006; Stone and Taske