Incidental Takes of Marine Mammals During Specified Activities; Low-Energy Marine Seismic Survey in the Northwest Atlantic Ocean, August 2009, 28890-28910 [E9-14380]

Agencies

• DEPARTMENT OF COMMERCE
• National Oceanic and Atmospheric Administration

[Federal Register Volume 74, Number 116 (Thursday, June 18, 2009)]
[Notices]
[Pages 28890-28910]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: E9-14380]


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

DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

RIN 0648-XO99


Incidental Takes of Marine Mammals During Specified Activities; 
Low-Energy Marine Seismic Survey in the Northwest Atlantic Ocean, 
August 2009

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

ACTION: Notice; proposed incidental take authorization; request for 
comments.

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

SUMMARY: NMFS has received an application from Rice University (Rice), 
for an Incidental Harassment Authorization (IHA) to take small numbers 
of marine mammals, by harassment, incidental to conducting a marine 
seismic survey in the Northwest Atlantic during August 2009. Pursuant 
to the Marine Mammal Protection Act (MMPA), NMFS requests comments on 
its proposal to authorize Rice to

[[Page 28891]]

incidentally take, by Level B harassment only, small numbers of marine 
mammals during the aforementioned activity.

DATES: Comments and information must be received no later than July 20, 
2009.

ADDRESSES: Comments on the application should be addressed to Michael 
Payne, Chief, Permits, Conservation and Education Division, Office of 
Protected Resources, National Marine Fisheries Service, 1315 East-West 
Highway, Silver Spring, MD 20910-3225. The mailbox address for 
providing e-mail comments is PR1.0648-XO99@noaa.gov. Comments sent via 
e-mail, including all attachments, must not exceed a 10-megabyte file 
size.
    A copy of the application containing a list of the references used 
in this document may be obtained by writing to 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.
    Documents cited in this notice may be viewed, by appointment, 
during regular business hours, at the aforementioned address.

FOR FURTHER INFORMATION CONTACT: Howard Goldstein or Ken Hollingshead, 
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 marine mammals by United 
States citizens who engage in a specified activity (other than 
commercial fishing) within a specified geographical region if certain 
findings are made and either regulations are issued or, if the taking 
is limited to harassment, a notice of a proposed authorization is 
provided to the public for review.
    Authorization for incidental taking shall be granted if NMFS finds 
that the taking will have a negligible impact on the species or 
stock(s), will not have an unmitigable adverse impact on the 
availability of the species or stock(s) for subsistence uses, and 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 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''].

16 U.S.C. 1362(18).
    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 
small numbers of marine mammals. Within 45 days of the close of the 
comment period, NMFS must either issue or deny issuance of the 
authorization.

Summary of Request

    On April 21, 2009, NMFS received an application from Rice for the 
taking, by Level B harassment only, of small numbers of marine mammals 
incidental to conducting, under a cooperative agreement with the 
National Science Foundation (NSF), a low-energy marine seismic survey 
in the Northwest Atlantic Ocean. The funding for the survey is provided 
by the NSF. The proposed survey will occur off New England within the 
U.S Exclusive Economic Zone (EEZ). Seismic operations will occur over 
the continental shelf southeast of the island of Martha's Vineyard, 
Massachusetts, and likely also in Nantucket Sound (see Figure 1 of 
Rice's application). The cruise is currently scheduled to occur from 
August 12 to 25, 2009. The survey will use two Generator Injector (GI) 
airguns with a discharge volume of 90 in\3\. Some minor deviation from 
these dates is possible, depending on logistics and weather.

Description of the Specified Activity

    Rice plans to conduct a low-energy marine seismic survey and 
bathymetric program. The planned survey will involve one source vessel, 
the R/V Endeavor (Endeavor), which will occur in the Northwest Atlantic 
Ocean off of New England.
    The proposed survey will examine stratigraphic controls on 
freshwater beneath the continental shelf off the U.S. east coast. In 
coastal settings worldwide, large freshwater volumes are sequestered in 
permeable continental shelf sediments. Freshwater storage and discharge 
have been documented off North and South America, Europe, and Asia. The 
proposed survey will investigate the Atlantic continental shelf off New 
England, where freshwater extends up to 100 km offshore. Using high-
resolution mathematical models and existing data, it is estimated that 
approximately 1,300 km\3\ (312 mi\3\) of freshwater is sequestered in 
the continental shelf from New York to Maine. However, the models 
indicate that the amount of sequestered freshwater is highly dependent 
on the thickness and distribution of aquifers and aquicludes. The 
proposed survey will provide imaging of the subsurface and characterize 
the distribution of aquifers and aquicludes off Martha's Vineyard.
    The study will provide data integral to improved models to estimate 
the abundance of sequestered freshwater and will provide site survey 
data for an Integrated Ocean Drilling Program (IODP) proposal to drill 
these freshwater resources for hydrogeochemical, biological, and 
climate studies. Combined seismic and drilling data could help identify 
undeveloped freshwater resources that may represent a resource to urban 
coastal centers, if accurately characterized and managed. On a global 
scale, vast quantities of freshwater have been sequestered in the 
continental shelf and may represent an increasingly valuable resource 
to humans. This survey will help constrain process-based mathematical 
models for more precise estimations of the abundance and distribution 
of freshwater wells on the continental shelf.
    The source vessel, the Endeavor, will deploy two low-energy GI 
airguns as an energy source (with a discharge volume of 90 in\3\) and a 
600 m (1,969 ft) towed hydrophone streamer. 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.
    The planned seismic program will consist of approximately 1,757 km 
(1,092 mi) of surveys lines and turns (see Figure 1 of Rice's 
application). Most of the survey effort (approximately 1,638 km or 
1,018 mi) will take place in water <100 m deep, and approximately 119 
km (74 mi) will occur just past the

[[Page 28892]]

shelf edge, in water depths >100 m (328 ft). There may be additional 
seismic operations associated with equipment testing, start-up, and 
repeat coverage of any areas where initial data quality is sub-
standard.
    All planned geophysical data acquisition activities will be 
conducted with assistance by scientists who have proposed the study, 
Dr. B. Dugan of Rice University, Dr. D. Lizarralde of Woods Hole 
Oceanographic Institution, and Dr. M. Person of New Mexico Institute of 
Mining and Technology. The vessel will be self-contained, and the crew 
will live aboard the vessel for the entire cruise.
    In addition to the seismic operations of the two GI airguns, a 
Knudsen 3260 echosounder, and EdgeTech sub-bottom profiler, and a 
``boomer'' system to image sub-bottom seafloor layers will be used at 
times during the survey.

Vessel Specifications

    The Endeavor has a length of 56.4 m (185 ft), a beam of 10.1 m 
(33.1 ft), and a maximum draft of 5.6 m (18.4 ft). The Endeavor has 
been operated by the University of Rhode Island's Graduate School of 
Oceanography for over thirty years to conduct oceanographic research 
throughout U.S. and world marine waters. The ship is powered by a 
single GM/EMD diesel engine, producing 3,050 hp, which drives a single 
propeller directly at a maximum of 900 revolutions per minute (rpm). 
The vessel also has a 320 hp bowthruster, which is not used during 
seismic acquisition. The optimal operation speed during seismic 
acquisition will be approximately 7.4 km/hour. When not towing seismic 
survey gear, the Endeavor can cruise at 18.5 km/hour. The Endeavor has 
a range of 14,816 km (9,206 mi). The Endeavor will also serve as the 
platform from which vessel-based Marine Mammal Visual Observers (MMVO) 
will watch for animals before and during GI airgun operations.

Acoustic Source Specifications

Seismic Airguns

    During the proposed survey, the Endeavor will tow two GI airguns, 
with a volume of 90 in\3\, and a 600 m long streamer containing 
hydrophones along predetermined lines. The two GI airguns will be towed 
approximately 25 m (82 ft) behind the Endeavor at a depth of 
approximately 3 m (10 ft). Seismic pulses will be emitted at intervals 
of approximately 5 seconds. At a speed of 7.4 km/hour, the 5 second 
spacing corresponds to a shot interval of approximately 10 m (33 ft). 
The operating pressure will be 2,000 psi. A single GI airgun will be 
used during turns.
    The generator chamber of each GI airgun, the one responsible for 
introducing the sound pulse into the ocean, has a volume of 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. Both GI airguns will be fired 
simultaneously, for a total discharge volume of 90 in\3\. The GI 
airguns are relatively small compared to most other airgun arrays used 
for seismic arrays.
    A single GI airgun, a single 15 in\3\ watergun, or a boomer system 
may be used in shallow waters with sandy seafloors if the two GI 
airguns do not provide accurate seafloor imaging. The watergun is a 
marine seismic sound source that uses an implosive mechanism to provide 
an acoustic signal. Waterguns provide a richer source spectra in high 
frequencies (>200 Hz) than those of GI or airguns. The 15 in\3\ 
watergun potentially provides a cleaner signal for high-resolution 
studies in shallow water, with a short-pulse (<30 ms) providing 
resolution of approximately 10 m. The operating pressure will be 2,000 
psi. Peak pressure of the single watergun and the boomer system is 
estimated to be approximately 212 dB (0.4 bar-m). Thus, both sources 
would have a considerably lower source level than the two GI airguns 
and single GI airgun.
    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 ``root mean square'' (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 to 172 dB, and to a peak-to-peak measurement of 
approximately 176 to 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 sound pressure field of two 45 in\3\ GI airguns has not been 
modeled, but those for two 45 in\3\ Nucleus G airguns and one 45 in\3\ 
GI airgun have been modeled by Lamont-Doherty Earth Observatory (L-DEO) 
of Columbia University in relation to distance and direction from the 
airguns (see Figure 2 and 3 of Rice's application). The GI airgun is 
essentially two G airguns that are joined head to head. The G airgun 
signal has more energy than the GI airgun signal, but the peak energy 
levels are equivalent and appropriate for modeling purposes. The L-DEO 
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 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) water are shown in Table 1 of Rice's application. Because the model 
results are for G airguns, which have more energy than GI airguns of 
the same size, those distances are overestimates of the distances for 
the 45 in\3\ GI airguns.

Echosounder

    The Knudsen 3260 is a deep-water, dual-frequency echosounder with 
operating frequencies of 3.5 and 12 kHz. The high frequency (12 kHz) 
can be used to record water depth or to track pingers attached to 
various instruments deployed over the side. The low frequency (3.5 kHz) 
is used for sub-bottom profiling. Both frequencies will be used 
simultaneously during the present study. It will be used with a hull-
mounted, downward-facing transducer. A pulse up to 24 ms in length is 
emitted every several seconds with a nominal beam width of 80[deg]. 
Maximum output power at 3.5 kHz is 10 kW and at 12 kHz it is 2 kW. The 
maximum source output (downward) for the 3260 is estimated to be 211 dB 
re 1 [mu]Pam at 10 kW.

Sub-bottom Profiler (SBP)

    The SBP is normally operated to provide information about 
sedimentary features and bottom topography; it will provide a 10 cm 
resolution of the sub-floor. During operations in deeper waters (>30-40 
m), an EdgeTech 3200-XS SBP will be operated from the ship with a SB-
512i towfish that will be towed at a depth of 5 m. It will transmit and 
record a 0.5-12 kHz swept pulse (or chirp), with a nominal beam width 
of 16-32[deg]. The SBP will produce a 30 ms pulse repeated at 0.5 to 1 
s intervals. Depending on seafloor conditions, it could penetrate up to 
100 m.

Boomer

    The `boomer' system will be an alternative source of sub-floor 
imaging in shallower waters (<30 to 40 m or 98 to 131 ft). The Applied 
Acoustics

[[Page 28893]]

AA200 `boomer' system, run by the National Oceanography Centre, 
operates at frequencies of approximately 0.3 to 3 kHz. The system will 
be surface-towed, and a 60 m (197 ft) hydrophone streamer will receive 
its pulses. The streamer will be towed at 1 m depth and approximately 
25 to 30 m (82 to 98 ft) behind the Endeavor. A 0.1 ms pulse will be 
transmitted at 1 s intervals. The normal source output (downward) is 
212 dB re 1 [mu]Pam.

Safety Radii

    NMFS has determined that for acoustic effects, using acoustic 
thresholds in combination with corresponding safety radii is the most 
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 compiled 
over the past decade, NMFS has used conservative numerical estimates to 
approximate where Level A harassment from acoustic sources begins: 180 
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 TTS) from 
single 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, Rice's application sets forth, and 
NMFS is using, the more conservative 180 and 190 dB re 1 [mu]Pa (rms) 
criteria. NMFS considers 160 re 1 [mu]Pa (rms) as the criterion for 
estimating the onset of Level B harassment from acoustic sources like 
impulse sounds used in the seismic survey.
    Emperical data concerning the 180 and 160 dB distances have been 
acquired based on measurements during the acoustic verification study 
conducted by L-DEO in the northern Gulf of Mexico from May 27 to June 
3, 2003 (Tolstoy et al., 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 [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 100-1,000 m and <100 
m; the proposed survey will occur in depths approximately 20 to 125 m.
    The empirical data indicate that, for deep water (>1,000 m), 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, 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 below). Therefore, the assumed 
180 and 190 dB radii are 40 m (131 ft) and 10 m (33 ft) respectively.
    Empirical measurements were not conducted for intermediate depths 
(100-1,000 m). On the expectation that results will be intermediate 
between those from shallow and deep water, a 1.5x correction factor is 
applied to the estimates provided by the model for deep water 
situations. This is the same factor that was applied to the model 
estimates during L-DEO cruises in 2003. The assumed 180 and 190 dB 
radii in intermediate depth water are 60 m (197 ft) and 15 m (49 ft), 
respectively (see Table 1 below).
    Empirical measurements indicated that in shallow water (<100 m), 
the L-DEO model underestimates actual levels. In previous L-DEO 
projects, the exclusion zones were typically based on measured values 
and ranged from 1.3 to 15x higher than the modeled values depending on 
the size of the airgun array and the sound level measured (Tolstoy et 
al., 2004a,b). During the proposed cruise, similar factors will be 
applied to derive appropriate shallow water radii from the modeled deep 
water radii (see Table 1 below). The assumed 180 and 190 dB radii in 
shallow depth water are 296 m (971 ft) and 147 m (482 ft), respectively 
(see Table 1 below).

                                                     Table 1
[Predicted distances to which sound levels >=190, 180, and 160 dB re 1 [mu]Pa might be received in shallow (<100
 m; 328 ft), intermediate (100-1,000 m; 328-3,280 ft), and deep (>1,000 m; 3,280 ft) water from the two 45 in\3\
 GI airguns used during the seismic surveys in the northwest Atlantic Ocean during August 2009, and one 45 in\3\
       GI airgun that will be used during turns. Distances are based on model results provided by L-DEO.]
----------------------------------------------------------------------------------------------------------------
                                                                            Predicted RMS distances (m)
       Source and volume         Tow depth (m)     Water depth   -----------------------------------------------
                                                                      190 dB          180 dB          160 dB
----------------------------------------------------------------------------------------------------------------
One GI airgun 45 in\3\........               3  Deep (>1,000 m).               8              23             220
                                               -----------------------------------------------------------------
                                ..............  Intermediate                  12              35             330
                                                 (100-1,000 m).
                                               -----------------------------------------------------------------
                                ..............  Shallow (<100 m)              95             150             570
----------------------------------------------------------------------------------------------------------------
Two GI airguns 45 in\3\.......               3  Deep (>1,000 m).              10              40             350
                                               -----------------------------------------------------------------
                                ..............  Intermediate                  15              60             525
                                                 (100-1,000 m).
                                               -----------------------------------------------------------------
                                ..............  Shallow (<100 m)             147             296           1,029
----------------------------------------------------------------------------------------------------------------

    The GI airguns, watergun, or boomer will be shut-down immediately 
when cetaceans are detected within or about to enter the 180 dB re 1 
[mu]Pa (rms) radius for the two GI airguns, or when pinnipeds are 
detected within or about to enter the 190 dB re 1 [mu]Pa (rms) radius 
for the two GI airguns. The 180 and 190 dB shut down criteria are 
consistent

[[Page 28894]]

with guidelines listed for cetaceans and pinnipeds, respectively, by 
NMFS (2000) and other guidance by NMFS. Proposed Dates, Duration, and 
Region of Activity
    The Endeavor is expected to depart from Narragansett, Rhode Island, 
on approximately August 12, 2009, for an approximately four hour 
transit to the study area southeast of Martha's Vineyard (see Figure 1 
of Rice's application). Seismic operations will commence upon arrival 
at the study area, with highest priority given to the central NNW-SSE 
line, followed by WSW-ENE lines, each of which cross the proposed IODP 
sites; lowest priority will be given to the survey lines in Nantucket 
Sound. The 14 day program will consist of approximately 11 days of 
seismic operations, and three contingency days in case of inclement 
weather. The Endeavor will return to Narragansett on approximately 
August 25, 2009. The exact dates of the proposed activities depend on 
logistics, weather conditions, and the need to repeat some lines if 
data quality is substandard.
    The proposed seismic survey will encompass the area 39.8[deg] to 
41.5[deg] N, 69.8[deg] to 70.6[deg] W (see Figure 1 of Rice's 
application). Water depths in the study area range from approximately 
20 to 125 m (66 to 410 ft), but are typically <100 m. The proposed 
survey will take place in Nantucket Sound and south of Nantucket and 
Martha's Vineyard. The ship will approach the south shore of Martha's 
Vineyard within 10 km (6.2 mi). The seismic survey will be conducted 
within the Exclusive Economic Zone (EEZ) of the U.S.A.

Description of Marine Mammals in the Proposed Activity Area

    A total of 34 marine mammal species (30 cetacean and 4 pinniped) 
are known to or may occur in the proposed study area (see Table 2, 
Waring et al., 2007). Several species are listed as Endangered under 
the Endangered Species Act (ESA): the North Atlantic right, humpback, 
sei, fin, blue, and sperm whales. The Western North Atlantic Coastal 
Morphotype Stock of common bottlenose dolphins is listed as Depleted 
under the MMPA.
    Table 2 below outlines the marine mammal species, their habitat, 
abundance, density, and conservation status in the proposed project 
area. Additional information regarding the distribution of these 
species expected to be found in the project area and how the estimated 
densities were calculated may be found in Rice's application.

                                                                         Table 2
[The occurrence, habitat, regional abundance, conservation status, best and maximum density estimates, number of marine mammals that could be exposed to
 sound level at or above 160dB re 1[mu]Pa, best estimate of number of individuals exposed, and best estimate of number of exposures per marine mammal in
     or near the proposed low-energy seismic survey area in the Northwest Atlantic Ocean. See Tables 2-4 in Rice's application for further detail.]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                  Density/     Density/
                Species                          Habitat            Occurrence in study area   Regional best abundance  ESA\a\   1000km \2\   1000km \2\
                                                                                                   est. (CV) \ 1\                  (best)       (max)
--------------------------------------------------------------------------------------------------------------------------------------------------------
              Mysticetes
 
North Atlantic right whale (Eubalaena   Coastal and shelf waters.  Common...................  325 (0) \2\.............     NL          N.A.         N.A.
 glacialis).
Humpback whale (Megaptera               Mainly nearshore waters    Common...................  11,570 \3\..............     EN          0.56        19.68
 novaeangliae).                          and banks.
Minke whale (Balaenoptera               Pelagic and coastal......  Common...................  188,000 \4\.............     NL          0.05         7.35
 acutorostrata).
Bryde's whale (Balaenoptera brydei)...  Primarily offshore,        Rare.....................  N.A.....................     NL          N.A.         N.A.
                                         pelagic.
Sei whale (Balaenoptera borealis).....  Primarily offshore,        Uncommon.................  10,300 \5\..............     EN          N.A.         N.A.
                                         pelagic.
Fin whale (Balaenoptera physalus).....  Continental slope, mostly  Common...................  35,500 \6\..............     EN          3.86        26.09
                                         pelagic.
Blue whale (Balaenoptera musculus)....  Pelagic, shelf and         Uncommon?................  1,186 \7\...............     EN          N.A.         N.A.
                                         coastal.
 
              Odontocetes
 
Sperm whale (Physeter macrocephalus)..  Usually pelagic and deep   Common?..................  13,190 \8\..............     EN          0.38        26.88
                                         seas.
Pygmy sperm whale (Kogia breviceps)...  Deep waters off shelf....  Uncommon.................  N.A.....................     NL          N.A.         N.A.
Dwarf sperm whale (Kogia sima)........  Deep waters off the shelf  Uncommon.................  N.A.....................     NL          N.A.         N.A.
Cuvier's beaked whale (Ziphius          Pelagic..................  Uncommon.................  N.A.....................     NL          N.A.         N.A.
 cavirostris).
Northern bottlenose whale (Hyperodon    Pelagic..................  Rare.....................  40,000 \9\..............     NL          N.A.         N.A.
 ampullatus).
True's beaked whale (Mesoplodon mirus)  Pelagic..................  Rare.....................  N.A.....................     NL          N.A.         N.A.
Gervais' beaked whale (Mesoplodon       Pelagic..................  Rare.....................  N.A.....................     NL          N.A.         N.A.
 europaeus).
Sowerby's beaked whale (Mesoplodon      Pelagic..................  Rare.....................  N.A.....................     NL          N.A.         N.A.
 bidens).
Blainville's beaked whale (Mesoplodon   Pelagic..................  Rare.....................  N.A.....................     NL          N.A.         N.A.
 densirostris).
Unidentified beaked whale.............  Pelagic..................  Rare.....................  N.A.....................     NL          0.01         0.82
Bottlenose dolphin (Tursiops            Coastal, shelf and         Common...................  81,588 (0.17) \10\......     NL         14.02       163.02
 truncatus).                             offshore.

[[Page 28895]]

 
Pantropical spotted dolphin (Stenella   Coastal and pelagic......  Rare.....................  N.A.....................     NL          N.A.         N.A.
 attenuata).
Atlantic spotted dolphin (Stenella      Mainly coastal waters....  Uncommon?................  50,978 (0.42)...........     NL          N.A.         N.A.
 frontalis).
Spinner dolphins (Stenella              Coastal and pelagic......  Rare.....................  N.A.....................     NL          N.A.         N.A.
 longirostris).
Striped dolphin (Stenella               Off continental shelf....  Common?..................  94,462 (0.40)...........     NL          0.11        73.61
 coeruleoalba).
Short-beaked common dolphin (Delphinus  Continental shelf and      Common...................  120,743 (0.23)..........     NL        128.88     1,108.71
 delphis).                               pelagic.
White-beaked dolphin (Lagenorhynchus    Continental shelf (<200    Uncommon?................  10s to 100s of 1,000s        NL          N.A.         N.A.
 albirostris).                           m).                                                   \11\.
Atlantic white-sided dolphin            Shelf and slope waters...  Common...................  10s to 100s of 1,000s        NL          N.A.         N.A.
 (Lagenorhynchus acutus).                                                                      \12\.
Risso's dolphin (Grampus griseus).....  Shelf, slope, seamounts    Common...................  20,479 (0.59)...........     NL          0.48       322.67
                                         (waters 400-1,000 m).
False killer whale (Pseudorca           Tropical, temperate,       Extralimital.............  N.A.....................     NL          N.A.         N.A.
 crassidens).                            pelagic.
Killer whale (Orcinus orca)...........  Coastal, widely            Rare.....................  N.A.....................    *NL          N.A.         N.A.
                                         distributed.
Long-finned pilot whale (Globlicephala  Mostly pelagic...........  Common?..................  810,000 \13\............     NL          N.A.         N.A.
 melas).
Short-finned pilot whale (Globicephala  Mostly pelagic, high-      Common?..................  810,000 \13\............     NL          N.A.         N.A.
 macrorhynchus).                         relief topography.
Unidentified pilot whale (Globicephala  Mostly pelagic...........  Common?..................  810,000 \13\............     NL          6.44       382.52
 sp.).
Harbor porpoise (Phocoena phocoena)...  Coastal and inland waters  Common?..................  500,000 \14\............     NL          N.A.         N.A.
 
               Pinnipeds
 
Harbor seal (Phoca vitulina)..........  Coastal..................  Common...................  99,340..................     NL          N.A.         N.A.
Gray seal (Halichoerus grypus)........  Coastal..................  Common...................  52,500 \15\.............     NL          N.A.         N.A.
Harp seal (Pagophilius groenlandicus).  Coastal..................  Uncommon.................  5,500,000 \16\..........     NL          N.A.         N.A.
Hooded seal (Cystophora cristata).....  Coastal..................  Uncommon.................  592,100 \17\............     NL          N.A.         N.A.
--------------------------------------------------------------------------------------------------------------------------------------------------------
N.A.--Data not available or species status was not assessed, ? indicated uncertainty
\a\ U.S. Endangered Species Act: EN = Endangered, T = Threatened, NL = Not listed
\1\ Abundance estimates are given from Waring et al. (2007), typically for U.S. Western North Atlantic stocks unless otherwise indicated; For species
  whose distribution is primarily offshore or not known, the estimates for the U.S. EEZ in Waring et al. (2007) are not considered for the study area
  and the regional population is given as N.A. unless it is available from another source.
\2\ Estimate updated in NMFS 2008 draft stock assessment report.
\3\ Estimate for the western North Atlantic (IWS, 2007a).
\4\ Estimate for the North Atlantic (IWC, 2007; Waring et al., 2007).
\5\ Estimate for the Northeast Atlantic (Cattanach et al., 1993).
\6\ Estimate for the North Atlantic (IWC, 2007a; Waring et al., 2007).
\7\ Estimate for the North Atlantic (NMFS, 1998).
\8\ Estimate for Northeast Atlantic (Whitehead, 2002).
\9\ Estimate for Northeast Atlantic (NAAMCO, 1995: 77).
\10\ Estimate for the Western North Atlantic and Offshore stock, and may include coastal forms. 43,951 animals estimated for all management units of the
  Coastal morphotype (Waring et al., 2007).
\11\ Tens to low hundreds of thousands (Reeves et al., 1999a).
\12\ High tens to low hundreds of thousands (Reeves et al., 1999b).
\13\ Estimate may include both long- and short-finned pilot whales.
\14\ Estimate for the North Atlantic (Jefferson et al., 2008)
\15\ Estimate for the northwest Atlantic Ocean in the Gulf of St. Lawrence and along the Nova Scotia eastern shore (Hammill, 2005).
\16\ Estimate for the northwest Atlantic Ocean (DFO, 2007).
\17\ Estimate for the northwest Atlantic Ocean (ICES, 2006).
*Southern Resident killer whales in the eastern Pacific Ocean, near Washington state, are listed as endangered under the ESA, but not in the Atlantic
  Ocean.
[caret]The Western North Atlantic Coastal Morphotype stock, ranging from NJ to FL, is listed as depleted under the MMPA.

    Several Federal Marine Protected Areas (MPAs) or sanctuaries have 
been established near the proposed study area, primarily with the 
intention of preserving cetacean habitat (see Table 3 of Rice's 
application; Hoyt, 2005; Cetacean Habitat, 2009; see also Figure 1 of 
Rice's application). Cape Cod Bay is designated as Right Whale Critical 
Habitat, as is the Great South Channel Northern Right Whale Critical 
Habitat Area located to the east of Cape Cod.

[[Page 28896]]

The Gerry E. Studds Stellwagen Bank National Marine Sanctuary is 
located north of the proposed study area in the Gulf of Maine. The 
proposed survey is not located within any Federal MPAs or sanctuaries. 
However, a sanctuary designated by the state of Massachusetts occurs 
within the study area--the Cape & Islands Ocean Sanctuary. This 
sanctuary includes nearshore waters of southern Cape Cod, Martha's 
Vineyard, and Nantucket (see Table 3 of Rice's application). In 
addition, there are four National Wildlife Refuges within the study 
area (Monomoy, Nantucket, Mashpee, and Nomans Island) and a National 
Estuarine Research Reserve (Waquoit Bay). Except for Nomans Island, 
these refuges and reserves are located in Nantucket Sound. Three 
Canadian protected areas also occur in the Northwest Atlantic for 
cetacean habitat protection, including the Bay of Fundy and Roseway 
Basin Right Whale Conservation Areas (see Figure 1 of Rice's 
application), as well as the Gully Marine Protected Area off the 
Scotian Shelf.
    There are several areas that are closed to commercial fishing on a 
seasonal basis to reduce the risk of entanglement or incidental 
mortality to marine mammals. To protect large whales like right, 
humpback, and fin whales, NMFS implemented seasonal area management 
zones for lobster, several groundfish, and other marine invertebrate 
trap/pot fisheries, prohibiting gear in the Great South Channel 
Critical Habitat Area from April through June; additional dynamic area 
management zones could be imposed for 15 day time periods if credible 
fisheries observers identify concentrations of right whales in areas 
north of 40[deg] N (NMFS 1999, 2008). To reduce fishery impacts on 
harbor porpoises, additional time and area closures in the Gulf of 
Maine include fall and winter along the mid-coastal area, winter and 
spring in Massachusetts Bay and southern Cape Cod, winter and spring in 
offshore areas, and February around Cashes Ledge (NMFS, 1998). 
Fishermen are also required to use pingers, and New Jersey and mid-
Atlantic waters could close seasonally for fishermen failing to apply 
specific gear modifications (NMFS, 1998).

Potential Effects 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, in the unlikely event that it occurred, 
would constitute injury, but temporary threshold shift (TTS) is not an 
injury (Southall et al., 2007). Although the possibility cannot be 
entirely excluded, it is unlikely that the project would result in any 
cases of permanent hearing impairment, or any significant non-auditory 
physical or physiological effects. Some behavioral disturbance is 
expected, but this would be localized and short-term.

Tolerance

    Numerous studies have shown that pulsed sounds from airguns are 
often readily detectable in the water at distances of many kilometers. 
For a brief summary of the characteristics of airgun pulses, see 
Appendix A of Rice's application. However, it should be noted that most 
of the measurements of airgun sounds would be detectable considerably 
farther away than the GI airguns planned for use in the proposed 
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 of Rice's application. 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 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 more so 
than would be the case for a larger airgun source typical of most 
seismic surveys.

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) 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.
    Some baleen and toothed whales are known to continue calling in the 
presence of seismic pulses. The airgun sounds are pulsed, with quiet 
periods between the pulses, and whale calls often can be heard between 
the seismic pulses (Richardson et al., 1986; McDonald et al., 1995; 
Greene et al., 1999; Nieukirk et al., 2004; Smultea et al., 2004; Holst 
et al., 2005a,b, 2006). In the northeast Pacific Ocean, blue whale 
calls have been recorded during a seismic survey off Oregon (McDonald 
et al., 1995). Among odontocetes, there has been one report that sperm 
whales cease 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., 2006, 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 the 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). Also, the sounds important to small odontocetes are 
predominantly at much higher frequencies than the airgun sounds, thus 
further 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 of Rice's application.

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

[[Page 28897]]

sound by changing its behavior or moving a small distance, the response 
may or may not rise to the level of ``harassment,'' or affect the stock 
or the species as a whole. 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 industrial 
activities, or exposed to a particular level of industrial sound. In 
most cases, this approach likely 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 disturbed to some biologically-important degree 
by a seismic program 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, bowhead, 
and on ringed seals. Less detailed data are available for some other 
species of baleen whales, sperm 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 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 of Rice's application, 
baleen whales exposed to strong noise pulses from airguns often react 
by deviating from their normal migration route and/or interrupting 
their feeding activities and moving away from the sound source. In the 
case of the 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.
    Studies of gray, bowhead, and humpback whales have demonstrated 
that 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. 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 
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 SIO's application 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 
220 to 570 m (722 to 1,870 ft) (see Table 1 above), as compared with 
several km when a large array of airguns is operating.
    Responses of humpback whales to seismic surveys have been studied 
during migration, on the 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, 2,678 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 to 8 km (3.1 to 5 mi) from the array, and that those 
reactions kept most pods approximately 3 to 4 km (1.9 to 2.5 mi) from 
the operating seismic boat. McCauley et al. (2000) noted localized 
displacement during migration of 4 to 5 km (2.5 to 3.1 mi) by traveling 
pods and 7 to12 km (4.3 to 7.5 mi) by cow-calf pairs. Avoidance 
distances with respect to the single airgun were smaller (2 km (1.2 
mi)) but consistent with the results from the full array in terms of 
received sound levels. The mean received level for initial avoidance 
reactions of an approaching airgun was a sound level of 140 dB re 1 
[mu]Pa (rms) for humpback whale pods containing females. The standoff 
range, i.e., the closest point of approach (CPA) 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 to 
8 km (3.1 to 5 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 to 400 m (328 to 1,312 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 1.64-L (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.
    Among wintering humpback whales off Angola (n = 52 useable groups), 
there were no significant differences in encounter rates (sightings/hr) 
when a 24 airgun array (3,147 in\3\ or 5,805 in\3\) was operating vs. 
silent (Weir, 2008). There was also no significant difference in the 
mean CPA distance of the humpback whale sightings when airguns were on 
vs. off (3,050 m vs. 2,700 m or 10,007 vs. 8,858 ft, respectively).
    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 humpbacks 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, 2007b:236).
    There are no data on reactions of right whales to seismic surveys, 
but results from the closely-related bowhead whale show that their 
responsiveness can be quite variable depending on the activity 
(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 Appendix A of Rice's EA). However, 
more recent research on bowhead whales (Miller et al., 2005a; Harris et 
al., 2007) corroborates earlier evidence that,

[[Page 28898]]

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 a received level of 
about 160-170 dB re 1 [mu]Pa (rms) (Richardson et al., 1986; Ljungblad 
et al., 1988; Miller et al., 2005a).
    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. Malme et al. (1986, 1988) 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. 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 (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.
    Various species of Balaenoptera (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). 
Sightings by observers on seismic vessels off the United Kingdom from 
1997 to 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 (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 of reactions) of cetaceans to 
impulsive noises do not necessarily provide information about long-term 
effects. It is 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 Outlaw, 2008). 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 continued to travel to the eastern Beaufort Sea each summer, and 
their numbers have increased notably, despite seismic exploration in 
their summer and autumn range for many years (Richardson et al., 1987). 
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 (Jochens and Biggs, 2003; Tyack et al., 2003; 
Jochens et al., 2006; Miller et al., 2006), 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; Weir, 2008).
    Seismic operators and MMOs 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 Tasker, 2006; Weir, 2008). Some dolphins 
seem to be attracted to the seismic vessel and floats, and some ride 
the bow wave of the seismic vessel even when large airgun arrays are 
firing (Moulton and Miller, 2005). Nonetheless, there have been 
indications that small toothed whales sometimes tend to head away or to 
maintain a somewhat greater distance from the vessel when a large array 
of airguns is operating than when it is silent (Stone and Tasker, 2006; 
Weir, 2008). In most cases, the avoidance radii for delphinids appear 
to be small, on the order of 1 km (0.62 mi) or less, and some 
individuals show no apparent avoidance. Weir (2008b) noted that a group 
of short-finned pilot whales initially showed an avoidance response to 
ramp-up of a large airgun array, but that this response was limited in 
time and space.
    The beluga is a species that (at least at times) shows long-
distance avoidance of seismic vessels. Aerial surveys during seismic 
operations in the southeastern Beaufort Sea during summer recorded much 
lower sighting rates of beluga whales within 10-20 km (6.2-12.4 mi) 
compared with 20-30 km (mi) from an operating airgun array, and 
observers on seismic boats in that area rarely see belugas (Miller et 
al., 2005a; Harris et al., 2007).
    Captive bottlenose dolphins and beluga whales exhibited changes in 
behavior when exposed to strong pulsed sounds similar in duration to 
those typically used in seismic surveys (Finneran et al., 2000, 2002, 
2005; Finneran and Schlundt, 2004). The animals tolerated high received 
levels of sound (pk-pk level >200 dB re 1 [mu]Pa) before exhibiting 
aversive behaviors. For pooled data at 3, 10, and 20 kHz, sound 
exposure levels during sessions with 25, 50, and 75 percent altered 
behavior were 180, 190, and 199 dB re 1 [mu]Pa\2\, respectively 
(Finneran and Schlundt, 2004).
    Results for porpoises depend on species. Dall's porpoises seem 
relatively tolerant of airgun operations (MacLean and Koski, 2005) and, 
during a survey with a large airgun array, tolerated higher noise 
levels than did harbor porpoises and gray whales (Bain and Williams, 
2006). However, Dall's porpoises do respond to the approach of large 
airgun arrays by moving away (Calambokidis and Osmek, 1998; Bain and 
Williams, 2006). The limited

[[Page 28899]]

available data suggest that harbor porpoises show stronger avoidance 
(Stone, 2003; Bain and Williams, 2006; Stone and Tasker, 2006). This 
apparent difference in responsiveness of these two porpoise species is 
consistent with their relative responsiveness to boat traffic and some 
other acoustic sources in general (Richardson et al., 1995; Southall et 
al. 2007).
    Most studies of sperm whales exposed to airgun sounds indicate that 
this species shows considerable tolerance of airgun pulses (Stone, 
2003; Moulton et al., 2005, 2006a; Stone and Tasker, 2006; Weir, 2008). 
In most cases, the whales do not show strong avoidance and continue to 
call (see Appendix A of Rice's EA for review). However, controlled 
exposure experiments in the Gulf of Mexico indicate that foraging 
effort is somewhat altered upon exposure to airgun sounds (Jochens et 
al., 2006, 2008). In the SWSS study, D-tags (Johnson and Tyack, 2003) 
were used to record the movement and acoustic exposure of eight 
foraging sperm whales before, during, and after controlled sound 
exposures of airgun arrays in the Gulf of Mexico (Jochens et al., 
2008). Whales were exposed to maximum received sound levels between 111 
and 147 dB re 1 [mu]Pa (rms) (131 to 164 dB re 1 [mu]Pa pk-pk) at 
ranges of approximately 1.4 to 12. 6 km (0.9 to 7.8 mi) from the sound 
source. Although the tagged whales showed no horizontal avoidance, some 
whales changed foraging behavior during full array exposure (Jochens et 
al., 2008).
    Odontocete reactions to large arrays of airguns are variable and, 
at least for delphinids and Dall's porpoises, seem to be confined to a 
smaller radius than has been observed for the more responsive of the 
mysticetes, belugas, and harbor porpoises (Appendix A of Rice's 
application). Thus behavioral reactions of most odontocetes to the 
small GI airgun source to be used during the proposed survey are 
expected to be very localized.
    Pinnipeds--In the event that any pinnipeds are encountered, they 
are not likely to show a strong avoidance reaction to the airgun array. 
Visual monitoring from seismic vessels has shown only slight (if any) 
avoidance of airguns by pinnipeds, and only slight (if any) changes in 
behavior (see Appendix A of Rice's application). In the Beaufort Sea, 
some ringed seals avoided an area of 100 m (at most) to a few hundred 
meters around seismic vessels, but many seals remained within 100 to 
200 m of the trackline as the operating airgun array passed by (e.g., 
Harris et al., 2001; Moulton and Lawson, 2002; Miller et al., 2005a). 
Ringed seal sightings averaged somewhat farther away from the seismic 
vessel when the airguns were operating than when they were not, but the 
difference was small (Moulton and Lawson, 2002). Similarly, in Puget 
Sound, sighting distances for harbor seals and California sea lions 
tended to be larger when airguns were operating (Calambokidis and 
Osmek, 1998). Previous telemetry work suggests that avoidance and other 
behavioral reactions may be stronger than evident to date from visual 
studies (Thompson et al, 1998). Nonetheless, reactions are expected to 
be confined to relatively small distances and durations, with no long-
term effects on pinniped individuals or populations.
    Additional details on the behavioral reactions (or the lack 
thereof) by all types of marine mammals to seismic vessels can be found 
in Appendix A of Rice's EA.

Hearing Impairment and Other Physical Effects

    Temporary or permanent hearing impairment is a possibility when 
marine mammals are exposed to very strong sounds. Temporary threshold 
shift (TTS) has been demonstrated and studied in certain captive 
odontocetes (and pinnipeds) exposed to strong sounds (reviewed in 
Southall et al., 2007). However, there has been no specific 
documentation of TTS let alone permanent hearing damage, i.e., 
permanent threshold shift (PTS), in free-ranging marine mammals exposed 
to sequences of airgun pulses during realistic field conditions.
    NMFS will be developing new noise exposure criteria for marine 
mammals that take account of the now-available scientific data on TTS, 
the expected offset between the TTS and PTS thresholds, differences in 
the acoustic frequencies to which different marine mammal groups are 
sensitive, and other relevant factors. Detailed recommendations for new 
science-based noise exposure criteria were published in late 2007 
(Southall et al., 2007).
    Because of the small GI airgun source in this proposed project, 
along with the proposed monitoring and mitigation measures, there is 
little likelihood that any marine mammals will be exposed to sounds 
sufficiently strong enough to cause hearing impairment. Several aspects 
of the proposed monitoring and mitigation measures for this project 
(see below) are designed to detect marine mammals occurring near the 
airguns (and other sound sources), and to avoid exposing them to sound 
pulses that might, at least in theory, cause hearing impairment. In 
addition, many cetaceans and (to a limited degree) pinnipeds are likely 
to show some avoidance of the area where received levels of airgun 
sound are high enough such that hearing impairment could potentially 
occur. In those cases, the avoidance responses of the animals 
themselves will reduce or (most likely) avoid any possibility of 
hearing impairment.
    Non-auditory physical effects may also occur in marine mammals 
exposed to strong underwater pulsed sound. Possible types of non-
auditory physiological effects or injuries that theoretically might 
occur in mammals close to a strong sound source include stress, 
neurological effects, bubble formation,