[Federal Register Volume 73, Number 101 (Friday, May 23, 2008)]
[Notices]
[Pages 30076-30093]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E8-11546]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

RIN 0648-XG64


Small Takes of Marine Mammals Incidental to Specified Activities; 
Low-Energy Marine Seismic Survey in the Northeast Pacific Ocean, June-
July 2008

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

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

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SUMMARY:  NMFS has received an application from University of Texas, 
Institute of Geophysics (UTIG) for an Incidental Harassment 
Authorization (IHA) to take marine mammals incidental to conducting a 
low-energy marine seismic survey in the Northeast Pacific Ocean during 
June-July, 2008. Pursuant to the Marine Mammal Protection Act (MMPA), 
NMFS is requesting comments on its proposal to issue an IHA to UTIG to 
incidentally take, by Level B harassment only, several species of 
marine mammals during the aforementioned activity.

DATES:  Comments and information must be received no later than June 
23, 2008.

ADDRESSES:  Comments on the application should be addressed to P. 
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 email comments is [email protected]. 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.
    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: http://www.nmfs.noaa.gov/pr/permits/incidental.htm#applications.
    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 U.S. 
citizens who engage in a specified activity (other than commercial 
fishing) within a specified geographical region if certain findings are 
made and either regulations are issued or, if the taking is limited to 
harassment, a notice of a proposed authorization is provided to the 
public for review.
    Authorization shall be granted if NMFS finds that the taking will 
have a negligible impact on the species or stock(s), will not have an 
unmitigable adverse impact on the availability of the species or 
stock(s) for subsistence uses (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. Except 
with respect to certain activities not pertinent here, the MMPA defines 
``harassment'' as:
    any act of pursuit, torment, or annoyance which (I) has the 
potential to injure a marine mammal or marine mammal stock in the 
wild [Level A harassment]; or (ii) has the potential to disturb a 
marine mammal or marine mammal stock in the wild by causing 
disruption of behavioral patterns, including, but not limited to, 
migration, breathing, nursing, breeding, feeding, or sheltering 
[Level B harassment].
    Section 101(a)(5)(D) establishes a 45-day time limit for NMFS 
review of an application followed by a 30-day public notice and comment 
period on any proposed authorizations for the incidental harassment of 
marine mammals. Within 45 days of the close of the comment period, NMFS 
must either approve or deny the authorization.

Summary of Request

    On March 4, 2008, NMFS received an application from UTIG for the 
taking, by Level B harassment only, of several

[[Page 30077]]

species of marine mammals incidental to conducting, with research 
funding from the National Science Foundation (NSF), a bathymetric and 
seismic survey program approximately 100 km (approximately 62 mi) off 
the Oregon coast in the Northeast Pacific Ocean during June-July, 2008. 
The purpose of the research program is to investigate the methane vent 
systems that exist offshore Oregon. These systems release methane by 
active venting at the seafloor. They can also form relatively high 
concentrations of methane hydrate in the sub seafloor, up to 150 m (492 
ft) below the sea bottom. The goal is to image these systems in detail 
to understand how vent structure directs methane from the subsurface to 
be vented into the oceans, or potentially stored in the subsurface as 
methane hydrate. Methane is a significant greenhouse gas, and methane 
release from vents or from hydrate has a significant potential to 
affect the Earth's climate. Hydrates are also a potentially significant 
source of energy. Also included in the research is the use of a 
multibeam echosounder and sub-bottom profiler.

Description of the Proposed Activity

    The seismic survey will involve one vessel, the R/V Thomas G. 
Thompson (Thompson), which is scheduled to depart from Seattle, 
Washington on June 30, 2008 and return on July 19, 2008. The exact 
dates of the activities may vary by a few days because of weather 
conditions, scheduling, repositioning, streamer operations and 
adjustments, GI airguns deployment, or the need to repeat some lines if 
data quality is substandard. The proposed ultra-high resolution 3-
dimensional (3-D) seismic surveys around the methane vent systems of 
Hydrate Ridge, will take place off the Oregon coast in the northeastern 
Pacific Ocean. The overall area within which the seismic surveys will 
occur is located between approximately 44[deg] and 45[deg] N. and 
124.5[deg] and 126[deg] W (Figure 1 in the application). The surveys 
will occur approximately 100 km (approximately 62 mi) offshore from 
Oregon in water depths between approximately 650 and 1,200 m (2,132 and 
3,936 ft), entirely within the Exclusive Economic Zone (EEZ) of the 
U.S.
    The seismic survey will image the subsurface structures that 
control venting. The vent systems control whether the methane is 
directly released into the ocean and atmosphere or stored in methane 
hydrate. Methane hydrate storage has the potential for rapid 
dissociation and release into the ocean or atmosphere. The subsurface 
structure that will be imaged will determine the mechanisms involved in 
methane venting. The results will be applicable to the numerous vent 
systems that exist on continental margins worldwide. The data will also 
be used to design observatories that can monitor and assess the methane 
fluxes and mechanisms of methane release that operate on Hydrate Ridge.
    The Thompson will deploy two low-energy Generator-Injector (GI) 
airguns (guns) as an energy source (with a discharge volume of 40-60 
in\3\ for each gun or a total of 80-120 in\3\) , and a P-Cable system. 
The 12 m (39.5 ft) long P-Cable system is supplied by Northampton 
Oceanographic Center in the U.K. The towed system will consist of at 
least 12 streamers (and possibly up to 24) spaced approximately 12.5 m 
(41 ft) apart and each containing 11 hydrophones, all summed to a 
single channel. The energy to the GI guns is compressed air supplied by 
compressors on board the source vessel. As the GI guns are towed along 
the survey lines, the P-Cable system will receive the returning 
acoustic signals.
    The seismic program will consist of three survey grids: two of the 
surveys each cover a 15 km2 area and the third covers a 25 km\2\ (see 
Figure 1 in UTIG's application). The line spacing within the three 
survey grids will either be 75 m (246 ft) (if 12 streamers are used) or 
150 m (492 ft) (if 24 streamers are used). The total line km to be 
surveyed in the grids at the 75 m spacing is 975 km (605.8 mi), 
including turns. Water depths at the seismic survey locations range 
from 650 to 1,200 m (2132 to 3936 ft). Most (92 percent) of the survey 
will take place over intermediate (100-1,000 m) water depths; the 
remaining 8 percent will be in water deeper than 1,000 m. If time 
permits, an additional 300 line km will be surveyed along the outside 
edges of the three grids. The GI guns are expected to operate for a 
total of approximately 150 hours during the cruise. There will be 
additional seismic operations associated with equipment testing, start-
up, and repeat coverage of any areas where initial data quality is sub-
standard.
    In addition to the operations of the two GI guns and P-cable 
system, a Simrad EM300 30 kHz multibeam echosounder, and a Knudsen 12 
kHz 320BR sub-bottom profiler will be used during the proposed cruise.

Vessel Specifications

    The Thompson has a length of 83.5 m (274 ft), a beam of 16 m (52.5 
ft), and a maximum draft of 5.8 m (19 ft). The ship is powered by twin 
360[deg]-azimuth stern thrusters a single 3,000-hp DC motor and a 
water-jet bow thruster powered by a 1,600-hp motor. The motors are 
driven by up to three 1,500-kW and three 715-kW generators; normal 
operations use two 1,500-kW and one 750-kW generator, but this changes 
with ship speed, sea state, and other variables. An operation speed of 
6.5 km/h (3.5 knots) will be used during seismic acquisition. When not 
towing seismic survey gear, the Thompson cruises at 22.2 km/h (12 
knots) and has a maximum speed of 26.9 km/h (14.5 knots). It has a 
normal operating range of approximately 24,400 km (8,264 mi).

Acoustic Source Specifications

Seismic Airguns
    The vessel Thompson will tow two GI guns and a P-Cable system of 12 
to 24, 12 m long streamers containing hydrophones along predetermined 
survey grids. Seismic pulses will be emitted at intervals of 3.5 s, 
which corresponds to a shot interval of approximately 6.3 m (20.7 ft) 
at a speed of 3.5 knots (6.5 km/h). The generator chamber of a GI gun, 
the one responsible for introducing the sound pulse into the ocean, is 
40-60 in3. The second injector chamber (40-60 in3) injects air into the 
previously-generated bubble to maintain its shape and does not 
introduce more sound into the water. The two 40-60 in3 GI guns will be 
towed 29 m (95.1 ft) behind the Thompson, at a depth of 1.5-3 m (4.9-
9.8 ft). The dominant frequency components are 0-188 Hz.
    The sound pressure field of two 105 in\3\ GI guns has been modeled 
by the Lamont-Doherty Earth Observatory (L-DEO) of Columbia University 
in relation to distance and direction from the GI guns. The model does 
not allow for bottom interactions and is most directly applicable to 
close distances and/or deep water. Because the L-DEO model is for a 
pair of larger GI guns with a total discharge of up to 210 in\3\, the 
values overestimate the distances for two GI guns with a discharge of 
up to 120 in3, as planned for use during the proposed study. This 
source, which is directed downward, was found to have an output (0-
peak) of 237 dB re 1 microPam.
    The root mean square (rms) received levels that are used as impact 
criteria for marine mammals are not directly comparable to the peak or 
peak to peak 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 rms in the far field would

[[Page 30078]]

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.
Sub-bottom Profiler
    The Thompson will utilize a Simrad EM300 30-kHz Multibeam 
Echosounder (MBES) as the primary bottom-mapping echosounder during the 
cruise. The Simrad EM300 transducer is hull-mounted within a transducer 
pod that is located midship. The system's normal operating frequency is 
approximately 30 kHz. The transmit fan-beam is split into either three 
or nine narrower beam sectors with independent active steering to 
correct for vessel yaw. Angular coverage is 36 degrees (in Extra Deep 
Mode, for use in water depths 3,000 to 6,000 m) or 150 degrees (in 
shallower water). The total angular coverage of 36 or 150 degrees 
consists of the 3 or 9 beams transmitted at slightly different 
frequencies. The sectors are frequency coded between 30 and 34 kHz and 
they are transmitted sequentially at each ping. Except in very deep 
water where the total beam is 36 x 1, the composite fan beam will 
overlap slightly if the vessel yaw is less than the fore-aft width of 
the beam (1,2, or 4, respectively). Achievable swath width on a flat 
bottom will normally be approximately 5x the water depth. The maximum 
source level is 237 dB re 1 microPam (rms) (Hammerstand, 2005). 
In deep water (500-3,000 m) a pulse length of 5 ms is normally used. At 
intermediate depths (100-1,000 m), a pulse length of 2 ms is used, and 
in shallow water (<300 m), a pulse length of 0.7 ms is used. The ping 
rate is mainly limited by the round trip travel time in the water up to 
a ping rate of 10 pings/s in shallow water.
    The Thompson will also utilize the Knudsen Engineering Model 320BR 
sub-bottom profiler, which is a dual-frequency echosounder designed to 
operate at 3.5 and/or 12 kHz. It is used to provide data about the 
sedimentary features that occur below the sea floor. The energy from 
the sub-bottom profiler is directed downward (in an 80-degree cone) via 
a 12 kHz transducer (EDO 323B) or a 3.5 kHz array of 16 ORE 137D 
transducers in a 4 x 4 arrangement. The maximum power output of the 
320BR is 10 kilowatts for the 3.5 kHz section and 2 kilowatts for the 
12 kHz section.
    The pulse length for the 3.5 kHz section of the 320BR 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 12 or 24 ms 
in this survey. The system produces one sound pulse and then waits for 
its return before transmitting again. Thus, the pulse interval is 
directly dependent upon water depth, and in this survey the interval is 
estimated to be every 4.5-8 sec. Using the Sonar Equations and assuming 
100 percent efficiency in the system (impractical in real world 
applications), the source level for the 320BR is calculated to be 211 
dB re 1 microPa-m. In practice, the system is rarely operated above 80 
percent power level.
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''. NMFS believes that to avoid permanent 
physiological damage (Level A Harassment), cetaceans and pinnipeds 
should not be exposed to pulsed underwater noise at received levels 
exceeding, respectively, 180 and 190 dB re 1 microPa (rms). NMFS also 
assumes that cetaceans or pinnipeds exposed to levels exceeding 160 dB 
re 1 microPa (rms) may experience Level B Harassment.
    Received sound levels have been modeled by L-DEO for a number of 
airgun configurations, including one 45-in\3\ GI gun, in relation to 
distance and direction from the airgun(s). 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 
gun where sound levels of 190, 180, and 160 dB re 1 microPa (rms) are 
predicted to be received in deep (>1000-m, 3280-ft) water are 8, 23, 
and 220 m (26.2, 75.5, and 721.8 ft), respectively and 12, 35, and 330 
m (39.4, 115, and 1,082.7 ft), respectively for intermediate water 
depths (100-1000m, 328-3,280 ft). Because the model results are for a 
2.5-m (8.2-ft) tow depth, the above distances slightly underestimate 
the distances for the 45-in\3\ GI gun towed at 4-m (13-ft) depth.
    Empirical data concerning the 180- and 160- dB distances have been 
acquired based on measurements during the acoustic verification study 
conducted by L-DEO in the northern Gulf of Mexico from 27 May to 3 June 
2003 (Tolstoy et al. 2004). Although the results are limited, the data 
showed that radii around the airguns where the received level would be 
180 dB re 1 microPa (rms) 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 (328-
3,280 ft) and <100 m (328 ft). The proposed survey will occur in depths 
650-1,200 m (2,132-3,936 ft), so the correction factors for the latter 
are not relevant here.
    The empirical data indicate that, for deep water (>1,000 m, 3,280 
ft), the L-DEO model tends to overestimate the received sound levels at 
a given distance (Tolstoy et al., 2004). However, to be precautionary 
pending acquisition of additional empirical data, it is proposed that 
safety radii during airgun operations in deep water will be the values 
predicted by L-DEO's model (above). Therefore, the assumed 180- and 
190-dB radii are 69 m and 20 m (226.3 and 65.6 ft), respectively.
    Empirical measurements were not conducted for intermediate depths 
(100-1,000 m, 328-3,280 ft). 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 104 m and 30 m (341.1 and 98.4 
ft), respectively.
    The GI guns will be shut down immediately when cetaceans or 
pinnipeds are detected within or about to enter the measured 180-dB 
(rms) or 190-dB (rms) radius, respectively.

Description of Marine Mammals in the Activity Area

    Thirty-two marine mammal species, including 19 odontocete (dolphins 
and small and large toothed whales) species, seven mysticete (baleen 
whales) species, five pinniped species, and the sea otter,

[[Page 30079]]

may occur or have been documented to occur in the marine waters off 
Oregon and Washington, excluding extralimital sightings or strandings 
(Table 1 here). Six of the species that may occur in the project area 
are listed under the U.S. Endangered Species Act (ESA) as endangered, 
including sperm, humpback, blue, fin, sei, and North Pacific right 
whales. In addition, the southern resident killer whale stock is also 
listed as endangered, but is unlikely to be seen in offshore waters of 
Oregon. The threatened Steller sea lion could also occur in the project 
area. However, the threatened northern sea otter is only known to occur 
in coastal waters and is not expected in the project area (the sea 
otter is under the jurisdiction of the U.S. Fish and Wildlife Service.
    Gray whales are also not expected in the project area because their 
occurrence off Oregon is limited to very shallow, coastal waters. The 
California sea lion, Steller sea lion, and harbor seal are also mainly 
coastal and are not expected at the survey locations. Information on 
habitat and abundance of the species that may occur in the study area 
are given in Table 1 below. Vagrant ringed seals, hooded seals, and 
ribbon seals have been sighted or stranded on the coast of California 
(see Mead, 1981; Reeves et al., 2002) and presumably passed through 
Oregon waters. A vagrant beluga was seen off the coast of Washington 
(Reeves et al., 2002).
    The six species of marine mammals expected to be most common in the 
deep pelagic or slope waters of the project area, where most of the 
survey sites are located, include the Pacific white-sided dolphin, 
northern right whale dolphin, Risso's dolphin, short-beaked common 
dolphin, Dall's porpoise, and northern fur seal (Green et al., 1992, 
1993; Buchanan et al., 2001; Barlow, 2003; Carretta et al., 2006).
    The sperm, pygmy sperm, mesoplodont species, Baird's beaked, and 
Cuvier's beaked whales and the northern elephant seal are considered 
pelagic species, but are generally uncommon in the waters near the 
survey 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 UTIG's application.

----------------------------------------------------------------------------------------------------------------
               Species                             Habitat                  Abundance\1\          Rqstd Take
----------------------------------------------------------------------------------------------------------------
Mysticetes                             ...............................  ....................  ..................
 
North Pacific right whale (Eubalaena   Inshore, occasionally offshore   N.A.\2\               0
 japonica) *
----------------------------------------------------------------------------------------------------------------
Humpback whale (Megaptera              Mainly nearshore waters and      1391                  1
 novaeangliae) *                        banks
----------------------------------------------------------------------------------------------------------------
Minke whale (Balaenoptera              Pelagic and coastal              1015                  1
 acutorostrata)
----------------------------------------------------------------------------------------------------------------
Sei whale (Balaenoptera borealis) *    Primarily offshore, pelagic      56                    0
----------------------------------------------------------------------------------------------------------------
Fin whale (Balaenoptera physalus) *    Continental slope, mostly        3279                  1
                                        pelagic
----------------------------------------------------------------------------------------------------------------
Blue whale (Balaenoptera musculus) *   Pelagic and coastal              1744                  0
----------------------------------------------------------------------------------------------------------------
Odontocetes                            ...............................  ....................  ..................
 
Sperm whale (Physeter macrocephalus)   Usually pelagic and deep seas    1233                  2
 *
----------------------------------------------------------------------------------------------------------------
Pygmy sperm whale (Kogia breviceps)    Deep waters off the shelf        247                   2
----------------------------------------------------------------------------------------------------------------
Dwarf sperm whale (Kogia sima)         Deep waters off the shelf        N.A.                  0
----------------------------------------------------------------------------------------------------------------
Cuvier's beaked whale (Ziphius         Pelagic                          1884                  0
 cavirostris)
----------------------------------------------------------------------------------------------------------------
Baird's beaked whale (Berardius        Pelagic                          228                   1
 bairdii)
----------------------------------------------------------------------------------------------------------------
Blainville's beaked whale (Mesoplodon  Slope, offshore                  1247 \3\              0
 densirostris)
----------------------------------------------------------------------------------------------------------------
Hubb's beaked whale (Mesoplodon        Slope, offshore                  1247 \3\              0
 carlhubbsi)
----------------------------------------------------------------------------------------------------------------
Stejneger's beaked whale (Mesoplodon   Slope, offshore                  1247 \3\              0
 stejnegeri)
----------------------------------------------------------------------------------------------------------------
Mesoplodon sp. (Unidentified)          Slope, offshore                  1247                  1
----------------------------------------------------------------------------------------------------------------
Offshore bottlenose dolphin (Tursiops  Offshore, slope                  5,065                 0
 truncatus)
----------------------------------------------------------------------------------------------------------------
Striped dolphin (Stenella              Off continental shelf            13,934                0
 coeruleoalba)
----------------------------------------------------------------------------------------------------------------
Short-beaked common dolphin            Shelf and pelagic, seamounts     449,846               7
 (Delphinus delphis)
----------------------------------------------------------------------------------------------------------------
Pacific white-sided dolphin            Offshore, slope                  59,274                6
 (Lagenorhynchus obliquidens)
----------------------------------------------------------------------------------------------------------------
Northern right whale dolphin           Slope, offshore waters           20,362                5
 (Lissodelphis borealis)
----------------------------------------------------------------------------------------------------------------
Risso's dolphin (Grampus griseus)      Shelf, slope, seamounts          16,066                3
----------------------------------------------------------------------------------------------------------------
False killer whale (Pseudorca          Pelagic, occasionally inshore    N.A.                  0
 crassidens)
----------------------------------------------------------------------------------------------------------------
Killer whale (Orcinus orca)            Widely distributed               466 (Offshore)        1
----------------------------------------------------------------------------------------------------------------

[[Page 30080]]

 
Short-finned pilot whale               Mostly pelagic, high-relief      304                   0
 (Globicephala macrorhynchus)           topography
----------------------------------------------------------------------------------------------------------------
Harbor porpoise (Phocoena phocoena)    Coastal and inland waters        39,586 (OR/WA)        0
----------------------------------------------------------------------------------------------------------------
Dall's porpoise (Phocoenoides dalli)   Shelf, slope, offshore           99,517                47
----------------------------------------------------------------------------------------------------------------
Pinnipeds                              ...............................  ....................  ..................
 
Northern fur seal (Callorhinus         Pelagic, offshore                688,028 \2\           19
 ursinus)
----------------------------------------------------------------------------------------------------------------
California sea lion (Zalophus          Coastal, shelf                   237,000-244,000       NA
 californianus californianus)
----------------------------------------------------------------------------------------------------------------
Northern elephant seal (Mirounga       Coastal, pelagic when migrating  101,000 (CA)          2
 angustirostris)
----------------------------------------------------------------------------------------------------------------
Table 1. Species expected to be encountered (and potentially harassed) during UTIG's NE Pacific Ocean cruise.
N.A. B Data not available or species status was not assessed.
* Species are listed as threatened or endangered under the Endangered Species Act.
\1\ Abundance given for U.S., Eastern North Pacific, or California/Oregon/Washington Stock, whichever is
  included in the 2005 U.S. Pacific Marine Mammal Stock Assessments (Carretta et al. 2006), unless otherwise
  stated.
\2\ Angliss and Outlaw (2005).
\3\ All mesoplodont whales

Potential Effects of Airguns

    The effects of sounds from airguns might include one or more of the 
following: tolerance, masking of natural sounds, behavioral 
disturbance, and temporary or permanent hearing impairment or non-
auditory physical or physiological effects (Richardson et al., 1995; 
Gordon et al., 2004). Given the small size of the GI guns planned for 
the proposed project, effects are anticipated to be considerably less 
than would be the case with a large array of airguns. It is very 
unlikely that there would be any cases of temporary or, especially, 
permanent hearing impairment or any significant non-auditory physical 
or physiological effects. Also, behavioral disturbance is expected to 
be limited to relatively short distances.
Tolerance
    Numerous studies have shown that pulsed sounds from airguns are 
often readily detectable in the water at distances of many kilometers. 
For a summary of the characteristics of airgun pulses, see Appendix A 
of UTIG's application. However, it should be noted that most of the 
measurements of airgun sounds that have been reported concerned sounds 
from larger arrays of airguns, whose sounds would be detectable 
considerably farther away than the two GI guns planned for use in the 
proposed project.
    Numerous other 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 (e) of UTIG's application). That is 
often true even in cases when the pulsed sounds appear to be readily 
audible to the animals based on measured received levels and the 
hearing sensitivity of that 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 and small odontocetes seem to be more tolerant of 
exposure to airgun pulses than are baleen whales. Given the relatively 
small, low-energy airgun source planned for use in this project, NMFS 
expects mammals to tolerate being closer to this source than for a 
larger airgun source typical of most seismic surveys. Mysticetes, 
odontocetes, pinnipeds and sea otters have all been seen commonly by 
observers aboard vessels conducting small-source seismic surveys, 
indicating some degree of tolerance of sounds from small airgun sources 
(e.g., Calambokidis et al., 2002; Haley and Koski, 2004; Holst et al., 
2005a; Ireland et al., 2005; MacLean and Koski, 2005; see also ``site 
survey'' portions of Stone, 2003 and Stone and Tasker, 2006).
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 
very few specific data on this matter. Some whales are known to 
continue calling in the presence of seismic pulses. Their calls can be 
heard between the seismic pulses (e.g., Richardson et al., 1986; 
McDonald et al., 1995; Greene et al., 1999; Nieukirk et al., 2004; 
Smultea et al., 2004). Although there has been one report that sperm 
whales cease calling when exposed to pulses from a very distant seismic 
ship (Bowles et al., 1994), a recent study reports that sperm whales 
off northern Norway continued calling in the presence of seismic pulses 
(Madsen et al., 2002c). Similar reactions have also been shown during 
recent work in the Gulf of Mexico (Tyack et al., 2003; Smultea et al., 
2004). Given the small source planned for use here, 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 smaller odontocete 
cetaceans, given the intermittent nature of seismic pulses and the 
relatively low source level of the airgun to be used here. Dolphins and 
porpoises are commonly heard calling while airguns are operating 
(Gordon et al., 2004; Smultea et al., 2004; Holst et al., 2005a,b). 
Also, the sounds important to small odontocetes are predominantly at 
much higher frequencies than are airgun sounds. Masking effects, in 
general, are discussed further in Appendix A (d) of UTIG'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). If a marine mammal responds to an underwater sound by 
changing its behavior or moving a small

[[Page 30081]]

distance, the response may or may not rise to the level of harassment, 
let alone affect the stock or the species as a whole. Alternatively, if 
a sound source displaces marine mammals from an important feeding or 
breeding area, effects on the stock or species could potentially be 
more than negligible. 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. This practice potentially 
overestimates the numbers of marine mammals that are affected in some 
biologically-important manner.
    The sound criteria 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, and bowhead whales and ringed seals. Less 
detailed data are available for some other species of baleen whales, 
sperm whales, and small toothed whales. Most of those studies have 
focused on the impacts resulting from the use of much larger airgun 
sources than those planned for use in the present 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 (e) of UTIG'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 determined that 
received levels of pulses in the 160-170 dB re 1 microPa (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 recent 
studies, reviewed in Appendix A (e) of UTIG's application, have shown 
that some species of baleen whales, notably bowheads and humpbacks, at 
times show strong avoidance at received levels lower than 160-170 dB re 
1 microPa (rms). Reaction distances would be considerably smaller 
during the present project, in which the 160-dB radius is predicted to 
be approximately 0.22 or 0.33 km (0.14 or 0.21 mi), 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 and on the summer feeding grounds, and there has also 
been discussion of effects on the Brazilian wintering grounds. McCauley 
et al. (1998, 2000) 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 microPa m. McCauley et al. (1998) documented that 
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. (2000) 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. Mean 
avoidance distance from the airgun corresponded to a received sound 
level of 140 dB re 1 microPa (rms); that was the level at which 
humpbacks started to show avoidance reactions to an approaching airgun. 
The standoff range, i.e., the closest point of approach of the whales 
to the airgun, corresponded to a received level of 143 dB re 1 microPa 
(rms). The initial avoidance response generally occurred at distances 
of 5-8 km (3.1-5 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 100-400 m (328-1,312 ft), where 
the maximum received level was 179 dB re 1 microPa (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 microPa on an 
approximate rms basis. Malme et al. (1985) conclude that there was no 
clear evidence of avoidance, despite the possibility of subtle effects, 
at received levels up to 172 re 1 microPa (approximately rms).
    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, 
subject to alternative explanations (IAGC 2004), and not consistent 
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 2007:236).
    Results from bowhead whales show that responsiveness of baleen 
whales to seismic surveys can be quite variable depending on the 
activity (migrating vs. feeding) of the whales. 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, where received sound levels were on the order of 
130 dB re 1 microPa (rms) (Miller et al., 1999; Richardson et al., 
1999). However, more recent research on bowhead whales (Miller et al., 
2005a) corroborates earlier evidence that, during the summer feeding 
season, bowheads are not as sensitive to seismic sources. In summer, 
bowheads typically begin to show avoidance reactions at a received 
level of about 160-170 dB re 1 microPa (rms) (Richardson et al., 1986; 
Ljungblad et al., 1988; Miller et al., 1999). There are no data on the 
reactions of wintering bowhead whales to seismic surveys. See Appendix 
A (e) of UTIG's application for more information regarding bowhead 
whale reactions to airguns.
    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

[[Page 30082]]

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 microPa 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 and on observations of Western Pacific gray whales feeding off 
Sakhalin Island, Russia (Johnson et al., 2007).
    Various species of Balaenoptera (blue, fin, sei, and minke whales) 
have occasionally been reported in areas ensonified by airgun pulses. 
Sightings by observers on seismic vessels off the U.K. from 1997 to 
2000 suggest that, at times of good sightability, numbers of rorquals 
seen are similar when airguns are shooting and not shooting (Stone, 
2003). Although individual species did not show any significant 
displacement in relation to seismic activity, all baleen whales 
combined were found to remain significantly further from the airguns 
during shooting compared with periods without shooting (Stone, 2003; 
Stone and Tasker, 2006). In a study off Nova Scotia, Moulton and Miller 
(2005) found little or no difference in sighting rates 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.
    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 despite intermittent seismic exploration and much ship 
traffic in that area for decades (Appendix A in Malme et al., 1984). 
Bowhead whales continued to travel to the eastern Beaufort Sea each 
summer despite seismic exploration in their summer and autumn range for 
many years (Richardson et al., 1987). In any event, the brief exposures 
to sound pulses from the present small 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, a systematic study on sperm 
whales has been done (Jochens and Biggs, 2003; Tyack et al., 2003; 
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; Bain and 
Williams, 2006; Holst et al., 2006; Stone and Tasker, 2006; Moulton and 
Miller, 2005).
    Seismic operators and marine mammal observers sometimes 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 limited avoidance of seismic vessels operating large airgun 
systems. However, 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 arrays of airguns are firing. 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 (Goold, 
1996; Calambokidis and Osmek, 1998; Stone, 2003). In most cases, the 
avoidance radii for delphinids appear to be small, on the order of 1 km 
(0.62 mi) or less.
    The beluga may be a species that (at least at times) shows long-
distance avoidance of seismic vessels. Aerial surveys during seismic 
operations in the southeastern Beaufort Sea recorded much lower 
sighting rates of beluga whales within 10-20 km (6.2-12.4 mi) of an 
active seismic vessel. These results were consistent with the low 
number of beluga sightings reported by observers aboard the seismic 
vessel, suggesting that some belugas might be avoiding the seismic 
operations at distances of 10-20 km (6.2-12.4 mi) (Miller et al., 
2005a). Similarly, captive bottlenose dolphins and beluga whales 
exhibit 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). 
However, the animals tolerated high received levels of sound (pk-pk 
level >200 dB re 1 microPa) before exhibiting aversive behaviors.
    Results for porpoises depend on species. Dall's porpoises seem 
relatively tolerant of airgun operations (MacLean and Koski, 2005; Bain 
and Williams, 2006), whereas the limited 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 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. In most 
cases, the whales do not show strong avoidance, and they continue to 
call (see Appendix A of UTIG's application for review). However, 
controlled exposure experiments in the Gulf of Mexico indicate that 
foraging effort is apparently somewhat reduced upon exposure to airgun 
pulses from a seismic vessel operating in the area, and there may be a 
delay in diving to foraging depth.
    There are no specific data on the behavioral reactions of beaked 
whales to seismic surveys. Most beaked whales tend to avoid approaching 
vessels of other types (Wursig et al., 1998). They may also dive for an 
extended period when approached by a vessel (Kasuya, 1986). It is 
likely that these beaked whales would normally show strong avoidance of 
an approaching seismic vessel, but this has not been documented 
explicitly.Odontocete reactions to large arrays of airguns are variable 
and, at least for delphinids and some porpoises, seem to be confined to 
a smaller radius than has been observed for mysticetes (see Appendix A 
of UTIG's application for more information). Behavioral reactions of 
most odontocetes to the small GI gun source to be used here are 
expected to be very localized.
    Pinnipeds - Pinnipeds are not likely to show a strong avoidance 
reaction to the two GI guns that will be used. Visual monitoring from 
seismic vessels, usually employing larger sources, has shown only 
slight (if any) avoidance of airguns by pinnipeds, and only slight (if 
any) changes in behavior (see Appendix A (e) of UTIG's application). 
Ringed seals frequently do not avoid the area within a few hundred 
meters of operating airgun arrays (Harris et al., 2001; Moulton and 
Lawson, 2002; Miller et al., 2005a). However, initial telemetry work 
suggests that avoidance and other behavioral reactions by two other 
species of seals to small airgun sources may at times be stronger than 
evident to date from visual studies of pinniped reactions to airguns 
(Thompson et al., 1998). Even if reactions of any pinnipeds that might 
be encountered in the present study area are as strong as those evident 
in the telemetry study, reactions are expected to be confined to 
relatively small distances and durations, with no long-

[[Page 30083]]

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 (e) of UTIG's application.

Hearing Impairment and Other Physical Effects

    Temporary or permanent hearing impairment is a possibility when 
marine mammals are exposed to very strong sounds, but there has been no 
specific documentation of this for marine mammals exposed to sequences 
of airgun pulses. Current NMFS policy regarding exposure of marine 
mammals to high-level sounds is that cetaceans and pinnipeds should not 
be exposed to impulsive sounds of 180 and 190 dB re 1 microPa (rms), 
respectively (NMFS, 2000). Those criteria have been used in defining 
the safety (shut-down) radii planned for the proposed seismic survey. 
The precautionary nature of these criteria is discussed in Appendix A 
(f) of UTIG's application, including the fact that the minimum sound 
level necessary to cause permanent hearing impairment is higher, by a 
variable and generally unknown amount, than the level that induces 
barely-detectable temporary threshold shift (TTS) (which NMFS' criteria 
are based on) and the level associated with the onset of TTS is often 
considered to be a level below which there is no danger of permanent 
damage. NMFS is presently 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 permanent threshold 
shift (PTS) thresholds, differences in the acoustic frequencies to 
which different marine mammal groups are sensitive, and other relevant 
factors.
    Because of the small size of the airgun source in this project (two 
40-60 in\3\ GI gun), alongwith the planned monitoring and mitigation 
measures, there is little likelihood that any marine mammals will be 
exposed to sounds sufficiently strong to cause hearing impairment. 
Several aspects of the planned monitoring and mitigation measures for 
this project are designed to detect marine mammals occurring near the 
GI guns (and multibeam echosounder and sub-bottom profiler), and to 
avoid exposing them to sound pulses that might, at least in theory, 
cause hearing impairment. In addition, many cetaceans are likely to 
show some avoidance of the area with high received levels of airgun 
sound (see above). 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, resonance effects, and other 
types of organ or tissue damage. It is possible that some marine mammal 
species (i.e., beaked whales) may be especially susceptible to injury 
and/or stranding when exposed to strong pulsed sounds. However, as 
discussed below, there is no definitive evidence that any of these 
effects occur even for marine mammals in close proximity to large 
arrays of airguns. It is especially unlikely that any effects of these 
types would occur during the present project given the small size of 
the source, the brief duration of exposure of any given mammal, and the 
planned monitoring and mitigation measures (see below). The following 
subsections discuss in somewhat more detail the possibilities of TTS, 
PTS, and non-auditory physical effects.
    Temporary Threshold Shift (TTS) - TTS is the mildest form of 
hearing impairment that can occur during exposure to a strong sound 
(Kryter, 1985). While experiencing TTS, the hearing threshold rises and 
a sound must be stronger in order to be heard. TTS can last from 
minutes or hours to (in cases of strong TTS) days. For sound exposures 
at or somewhat above the TTS threshold, hearing sensitivity recovers 
rapidly after exposure to the noise ends. Few data on sound levels and 
durations necessary to elicit mild TTS have been obtained for marine 
mammals, and none of the published data concern TTS elicited by 
exposure to multiple pulses of sound.
    For toothed whales exposed to single short pulses, the TTS 
threshold appears to be, to a first approximation, a function of the 
energy content of the pulse (Finneran et al. 2002, 2005). Given the 
available data, the received level of a single seismic pulse (with no 
frequency weighting) might need to be approximately 186 dB re 1 
microPa\2\s (i.e., 186 dB SEL or approximately 221-226 dB pk-
pk) in order to produce brief, mild TTS. Exposure to several strong 
seismic pulses that each have received levels near 175-180 dB SEL might 
result in slight TTS in a small odontocete, assuming the TTS threshold 
is (to a first approximation) a function of the total received pulse 
energy. The distances from the Thompson's GI guns at which the received 
energy level (per pulse) would be expected to be [gteqt]175-180 dB SEL 
are the distances shown in the 190 dB re 1 microPa (rms) column in 
Table 1 of UTIG's application (given that the rms level is 
approximately 10-15 dB higher than the SEL value for the same pulse). 
Seismic pulses with received energy levels [gteqt]175-180 dB SEL (190 
dB re 1 microPa (rms)) are expected to be restricted to radii no more 
than 69-104 m (226.3-341.1 ft) around the two GI guns. The specific 
radius depends on the depth of the water. For an odontocete closer to 
the surface, the maximum radius with [gteqt]175-180 dB SEL or 
[gteqt]190 dB re 1 microPa (rms) would be smaller. Such levels would be 
limited to distances within tens of meters of the small GI guns source 
to be used in this project.
    For baleen whales, direct or indirect data do not exist on levels 
or properties of sound thatare required to induce TTS. The frequencies 
to which baleen whales are most sensitive are lower than those to which 
odontocetes are most sensitive, and natural background noise levels at 
those low frequencies tend to be higher. As a result, auditory 
thresholds of baleen whales within their frequency band of best hearing 
are believed to be higher (less sensitive) than are those of 
odontocetes at their best frequencies (Clark and Ellison, 2004). From 
this, it is suspected that received levels causing TTS onset may also 
be higher in baleen whales. In any event, no cases of TTS are expected 
given three considerations: (1) the low abundance of baleen whales 
expected in the planned study areas; (2) the strong likelihood that 
baleen whales would avoid the approaching airguns (or vessel) before 
being exposed to levels high enough for there to be any possibility of 
TTS; and (3) the mitigation measures that are proposed to be 
implemented.
    In pinnipeds, TTS thresholds associated with exposure to brief 
pulses (single or multiple) of underwater sound have not been measured. 
Initial evidence from prolonged exposures suggests that some pinnipeds 
may incur TTS at somewhat lower received levels than do small 
odontocetes exposed for similar durations (Kastak et al., 1999, 2005; 
Ketten et al., 2001; cf. Au et al., 2000). The TTS threshold for pulsed 
sounds has been indirectly estimated as being an SEL of about 171 dB re 
microPa\2\s (Southall et al., 2007), which would be equivalent 
to about 181-186 dB re 1 microPa (rms). Corresponding values for 
California sea lions and northern elephant seals are likely to be 
higher (Kastak et al., 2005).
    To avoid injury, NMFS has determined that cetaceans and pinnipeds 
should not be exposed to

[[Page 30084]]

pulsed underwater noise at received levels exceeding, respectively, 180 
and 190 dB re 1 microPa (rms). Those sound levels were not considered 
to be the levels above which TTS might occur. Rather, they were the 
received levels above which, in the view of a panel of bioacoustics 
specialists convened by NMFS before TTS measurements for marine mammals 
started to become available, one could not be certain that there would 
be no injurious effects, auditory or otherwise, to marine mammals. As 
summarized above, data that are now available imply that TTS is 
unlikely to occur unless odontocetes (and probably mysticetes as well) 
are exposed to airgun pulses stronger than 180 dB re 1 microPa (rms).
    Permanent Threshold Shift (PTS) - When PTS occurs, there is 
physical damage to the sound receptors in the ear. In some cases, there 
can be total or partial deafness, while in other cases, the animal has 
an impaired ability to hear sounds in specific frequency ranges.
    There is no specific evidence that exposure to pulses of airgun 
sound can cause PTS in any marine mammal, even with large arrays of 
airguns. However, given the possibility that mammals close to an airgun 
array might incur TTS, there has been further speculation about the 
possibility that some individuals occurring very close to airguns might 
incur PTS. Single or occasional occurrences of mild TTS are not 
indicative of permanent auditory damage in terrestrial mammals. 
Relationships between TTS and PTS thresholds have not been studied in 
marine mammals, but are assumed to be similar to those in humans and 
other terrestrial mammals. PTS might occur at a received sound level at 
least several decibels above that inducing mild TTS if the animal were 
exposed to strong sound pulses with rapid rise time (see Appendix A (f) 
of UTIG's application). The specific difference between the PTS and TTS 
thresholds has not been measured for marine mammals exposed to any 
sound type. However, based on data from terrestrial mammals, a 
precautionary assumption is that the PTS threshold for impulse sounds 
(such as airgun pulses as received close to the source) is at least 6 
dB higher than the TTS threshold on a peak-pressure basis and probably 
more than 6 dB.
    On an SEL basis, Southall et al. (2007) estimate that received 
levels would need to exceed the TTS threshold by at least 15 dB for 
there to be risk of PTS. Thus, for cetaceans they estimate that the PTS 
threshold might be an SEL of about 198 dB re 1 microPa\2\.s. Additional 
assumptions had to be made to derive a corresponding estimate for 
pinnipeds. Southall et al. (2007) estimate that the PTS threshold could 
be an SEL of about 186 dB re 1 microPa\2\s in the harbor seal; 
for the California sea lion and northern elephant seal the PTS 
threshold would probably be higher. Southall et al. (2007) also not 
that, regardless of the SEL, there is concern about the possibility of 
PTS if a cetacean or pinniped received one or more pulses with peak 
pressure exceeding 230 or 218 dB 1 microPa (peak).
    In the proposed project employing two 40 to 60-in\3\ GI guns, 
marine mammals are highly unlikely to be exposed to received levels of 
seismic pulses strong enough to cause TTS, as they would probably need 
to be within a few tens of meters of the GI guns for that to occur. 
Given the higher level of sound necessary to cause PTS, it is even less 
likely that PTS could occur. In fact, even the levels immediately 
adjacent to the GI guns may not be sufficient to induce PTS, especially 
since a mammal would not be exposed to more than one strong pulse 
unless it swam immediately alongside the GI guns for a period longer 
than the inter-pulse interval. Baleen whales generally avoid the 
immediate area around operating seismic vessels, as do some other 
marine mammals and sea turtles. The planned monitoring and mitigation 
measures, including visual monitoring and shut downs of the GI guns 
when mammals are seen within or about to enter the ``safety radii'' or 
exclusion zone (EZ), will minimize the already-minimal probability of 
exposure of marine mammals to sounds strong enough to induce PTS.
    Non-auditory Physiological Effects - Non-auditory physiological 
effects or injuries that theoretically might occur in marine mammals 
exposed to strong underwater sound include stress, neurological 
effects, bubble formation, resonance effects, and other types of organ 
or tissue damage. However, studies examining such effects are limited. 
If any such effects do occur, they would probably be limited to unusual 
situations when animals might be exposed at close range for unusually 
long periods, when the sound is strongly channeled with less-than-
normal propagation loss, or when dispersal of the animals is 
constrained by shorelines, shallows, etc. Airgun pulses, because of 
their brevity and intermittence, are less likely to trigger resonance 
or bubble formation than are more prolonged sounds. It is doubtful that 
any single marine mammal would be exposed to strong seismic sounds for 
time periods long enough to induce physiological stress.
    Until recently, it was assumed that diving marine mammals are not 
subject to the bends or air embolism. This possibility was first 
explored at a workshop (Gentry [ed.], 2002) held to discuss whether the 
stranding of beaked whales in the Bahamas in 2000 (Balcomb and 
Claridge, 2001; NOAA and USN, 2001) might have been related to bubble 
formation in tissues caused by exposure to noise from naval sonar. 
However, this link could not be confirmed. Jepson et al. (2003) first 
suggested a possible link between mid-frequency sonar activity and 
acute chronic tissue damage that results from the formation in vivo of 
gas bubbles, based on the beaked whale stranding in the Canary Islands 
in 2002 during naval exercises. Fernandez et al. (2005a) showed those 
beaked whales did indeed have gas bubble-associated lesions, as well as 
fat embolisms. Fernandez et al. (2005b) also found evidence of fat 
embolism in three beaked whales that stranded 100 km (62 mi) north of 
the Canaries in 2004 during naval exercises. Examinations of several 
other stranded species have also revealed evidence of gas and fat 
embolisms (Arbelo et al., 2005; Jepson et al., 2005a; Mendez et al., 
2005). Most of the afflicted species were deep divers. There is 
speculation that gas and fat embolisms may occur if cetaceans ascend 
unusually quickly when exposed to aversive sounds, or if sound in the 
environment causes the destablization of existing bubble nuclei 
(Potter, 2004; Arbelo et al., 2005; Fernandez et al., 2005a; Jepson et 
al., 2005b; Cox et al., 2006). Even if gas and fat embolisms can occur 
during exposure to mid-frequency sonar, there is no evidence that that 
type of effect occurs in response to airgun sounds.
    In general, little is known about the potential for seismic survey 
sounds to cause auditory impairment or other physical effects in marine 
mammals. Available data suggest that such effects, if they occur at 
all, would be limited to short distances and probably to projects 
involving large arrays of airguns. However, the available data do not 
allow for meaningful quantitative predictions of the numbers (if any) 
of marine mammals that might be affected in those ways. Marine mammals 
that show behavioral avoidance of seismic vessels, including most 
baleen whales, some odontocetes, and some pinnipeds, are especially 
unlikely to incur auditory impairment or other physical effects. Also, 
the planned mitigation measures, including shut downs of the GI guns, 
will reduce any such effects that might otherwise occur.

[[Page 30085]]

Strandings and Mortality
    Marine mammals close to underwater detonations of high explosives 
can be killed or severely injured, and their auditory organs are 
especially susceptible to injury (Ketten et al., 1993; Ketten, 1995). 
Airgun pulses are less energetic and have slower rise times, and there 
is no proof that they can cause serious injury, death, or stranding 
even in the case of large airgun arrays. However, the association of 
mass strandings of beaked whales with naval exercises and, in one case, 
an L-DEO seismic survey, has raised the possibility that beaked whales 
exposed to strong pulsed sounds may be especially susceptible to injury 
and/or behavioral reactions that can lead to stranding. Appendix A of 
UTIG's application provides additional details.
    Seismic pulses and mid-frequency sonar pulses are quite different. 
Sounds produced by airgun arrays are broadband with most of the energy 
below 1 kHz. Typical military mid-frequency sonars operate at 
frequencies of 2-10 kHz, generally with a relatively narrow bandwidth 
at any one time. Thus, it is not appropriate to assume that there is a 
direct connection between the effects of military sonar and seismic 
surveys on marine mammals. However, evidence that sonar pulses can, in 
special circumstances, lead to physical damage and mortality (Balcomb 
and Claridge, 2001; NOAA and USN, 2001; Jepson et al., 2003; Fernandez 
et al., 2004, 2005a; Cox et al., 2006), even if only indirectly, 
suggests that caution is warranted when dealing with exposure of marine 
mammals to any high-intensity pulsed sound.
    There is no conclusive evidence of cetacean strandings as a result 
of exposure to seismic surveys. Speculation concerning a possible link 
between seismic surveys and strandings of humpback whales in Brazil 
(Engel et al., 2004) was not well founded based on available data 
(IAGC, 2004; IWC, 2006). In September 2002, there was a stranding of 
two Cuvier's beaked whales in the Gulf of California, Mexico, when the 
L-DEO research vessel Maurice Ewing was operating a 20-gun, 8,490-in\3\ 
array in the general area. The link between the stranding and the 
seismic survey was inconclusive and not based on any physical evidence 
(Hogarth, 2002; Yoder, 2002). Nonetheless, the preceding example plus 
the incidents involving beaked whale strandings near naval exercises 
suggests a need for caution in conducting seismic surveys in areas 
occupied by beaked whales. No injuries of beaked whales are anticipated 
during the proposed study because of the proposed monitoring and 
mitigation measures.
    The proposed project will involve a much smaller sound source than 
used in typical seismic surveys. That, along with the monitoring and 
mitigation measures that are planned, are expected to minimize any 
possibility for strandings and mortality.

Potential Effects of Other Acoustic Devices

Multibeam Echosounder Signals
    A Simrad EM300 30-kHz MBES will be operated from the source vessel 
during approximately two days of the proposed study. Sounds from the 
MBES are very short pulses occurring for 2-5 ms, at a ping rate of up 
to 10 pings/s depending on depth. Given the minimum water depth in the 
study area (650 m; 2-way travel time [gteqt]0.9 s), the pulse 
repetition rate is not likely to exceed 1 ping/s. Most of the energy in 
the sound pulses emitted by the MBES is at freqencies near 30 kHz 
within the audible range for odontocetes and at least some pinnipeds, 
but probably not for baleen whales (Southall et al., 2007). The beam is 
narrow (1-4[deg]) in fore-aft extent and wide (150[deg]) in the cross-
track extent. Each ping consists of nine beams transmitted at slightly 
different frequencies. Any given mammal at depth near the trackline 
would be in the main beam for only one or two of the nine segments. 
Also, marine mammals that encounter the Simrad EM300 are unlikely to be 
subjected to repeated pulses because of the narrow fore-aft width of 
the beam and will receive only limited amounts of pulse energy because 
of the short pulses. Animals close to the ship (where the beam is 
narrowest) are especially unlikely to be ensonified for more than one 5 
ms pulse (or two pulses if in the overlap area). Similarly, Kremser et 
al. (2005) noted that the probability of a cetacean swimming through 
the area of exposure when MBES emits a pulse is small due to the narrow 
beam being emitted. The animal would have to pass the transducer at 
close range and be swimming at speeds similar to the vessel in order to 
be subjected to sound levels that could cause TTS. Burkhardt et al. 
(2007) concluded that immediate direct injury was possible only if a 
cetacean dived under the vessel into the immediate vicinity of the 
transducer.
    Navy sonars that have been linked to avoidance reactions and 
stranding of cetaceans (1) generally have a longer pulse duration than 
the Simrad EM300, and (2) are often directed close to horizontally vs. 
more downward for the MBES. The area of possible influence of the MBES 
is much smaller a narrow band below the source vessel. The duration of 
exposure for a given marine mammal can be much longer for a navy sonar. 
Possible effects of an MBES on marine mammals are outlined below.
    Marine mammal communications will not be masked appreciably by the 
MBES signals given its low duty cycle and the brief period when an 
individual mammal is likely to be within its beam. Furthermore, in the 
case of baleen whales, the signals (30 kHz) do not overlap with the 
frequencies in the calls or with the functional hearing range, which 
would avoid any possibility of masking.
    Behavioral reactions of free ranging marine mammals to echosounders 
and other sound sources appear to vary by species and circumstance. 
Observed reactions have included silencing and dispersal by sperm 
whales (Watkins et al., 1985), increased vocalizations and no dispersal 
by pilot whales (Rendell and Gordon, 1999), and the previously-
mentioned beachings by beaked whales. During exposure to a 21-25 kHz 
whale-finding sonar with a source level of 215 dB re 1 microPam, gray 
whales showed slight avoidance (~200 m or 656 ft) behavior (Frankel, 
2005). However, all of those observations are of limited relevance to 
the present situation. Pulse durations from those sonars were much 
longer than those of the MBES, and a given mammal would have received 
many pulses from the naval sonars. During UTIG's operations, the 
individual pulses will be very short, and a given mammal would not 
receive many of the downward-directed pulses as the vessel passes by. 
In the case of baleen whales, the MBES will operate at too high a 
frequency to have any effect.
    Captive bottlenose dolphins and a beluga whale exhibited changes in 
behavior when exposed to 1 s pulsed sounds at frequencies similar to 
those that will be emitted by the MBES used by UTIG, and to shorter 
broadband pulsed signals. Behavioral changes typically involved what 
appeared to be deliberate attempts to avoid the sound exposure 
(Schlundt et al., 2000; Finneran et al., 2002; Finneran and Schlundt, 
2004). The relevance of those data to free-ranging odontocetes is 
uncertain, and in any case the test sounds were quite different in 
either duration or bandwidth as compared with those from an MBES.
    During a previous low-energy seismic survey from the Thompson, the 
EM300 MBES was in operation most of the time. Many cetaceans and small 
numbers of fur seals were seen by marine mammal visual observers 
(MMVOs) aboard the ship, but no

[[Page 30086]]

specific information about MBES effects (if any) on mammals was 
obtained (Ireland et al., 2005). These responses (if any) could not be 
distinguished from responses to the airgun (when operating) and to the 
ship itself.
    Given recent stranding events that have been associated with the 
operations of naval sonar, there is concern that mid-frequency sonar 
sounds can cause serious impacts to marine mammals (see above). 
However, the MBES proposed for use by UTIG is quite different than 
sonars used for navy operations. Pulse duration of the MBES is very 
short relative to naval sonars. Also, at any given location, an 
individual marine mammals would be in the beam of the MBES for much 
less time given the generally downward orientation of the beam and its 
narrow fore-aft beamwidth; navy sonars often use near horizontally 
directed sound. Those factors would all reduce the sound energy 
received from the MBES rather drastically relative to that from the 
sonars used by the navy.
    Although the source level of the Simrad EM300 is not available, the 
maximum source level of a relatively powerful MBES (Simrad EM120) is 
242 dB re 1 microParms. At that source level, the received 
level for an animals within the MBES beam 100 m below the ship would be 
~202 dB re 1 microPa (rms), assuming 40 dB of spreading loss over 100 m 
(circular spreading). Given the narrow beam, only one pulse is likely 
to be received by a given animal. The received energy from a single 
pulse of duration 5 ms would be about 179 dB 1 microPas, i.e., 
202 dB+10 log (0.005 s). That would be below the TTS thresholds for an 
odontocete or pinniped exposed to a single non-impulsive sonar 
transmission (195 and [gteqt]183 dB re 1 microPas, 
respectively) and even further below the anticipated PTS threshold (215 
and [gteqt]203 dB re 1 microPas, respectively) (Southall et 
al., 2007). In contrast, an animal that was only 10 m below the MBES 
when a ping is emitted would be expected to receive a level 20 dB 
higher, i.e., 199 dB re 1 Pa s in the case of the EM120. That animal 
might incur some TTS (which would be fully recoverable), but the 
exposure would still be below the anticipated PTS threshold for both 
cetaceans and pinnipeds.
Chirp Echosounder Signals
    A chirp echosounder or sub-bottom profiler will be operated from 
the source vessel at all times during the proposed study. Sounds from 
the sub-bottom profiler are very short pulses, occurring for up to 24 
ms once every few seconds. Most of the energy in the sound pulses 
emitted by this sub-bottom profiler is at 12 kHz, and the beam is 
directed downward. The source level of the chirp is expected to be 
lower than that of the MBES. Kremser et al. (2005) noted that the 
probability of a cetacean swimming through the area exposure when an 
echosounder emits a pulse is small, and if the animal was in the area, 
it would have to pass the transducer at close range in order to be 
subjected to sound levels that could cause TTS.
    Marine mammal communications will not be masked appreciably by the 
sub-bottom profiler signals given their directionality and the brief 
period when an individual mammal is likely to be within its beam. 
Furthermore, in the case of most odontocetes, the sonar signals do not 
overlap with the predominant frequencies in the calls, which would 
avoid significant masking.
    Marine mammal behavioral reactions to other pulsed sound sources 
are discussed above, and responses to the sub-bottom profiler are 
likely to be similar to those for other pulsed sources if received at 
the same levels. However, the pulsed signals from the chirp are 
somewhat weaker than those from the MBES. Therefore, behavioral 
responses are not expected unless marine mammals are very close to the 
source.
    Source levels of the chirp are much lower than those of the airguns 
and the MBES, which are discussed above. Thus, it is unlikely that the 
chirp produces pulse levels strong enough to cause hearing impairment 
or other physical injuries even in an animal that is (briefly) in a 
position near the source. The chirp is often operated simultaneously 
with other higher-power acoustic sources. Many marine mammals will move 
away in response to the approaching higher-power sources or the vessel 
itself before the mammals would be close enough for there to be any 
possibility of effects from the less intense sounds from the chirp. In 
the case of mammals that do not avoid the approaching vessel and its 
various sound sources, mitigation measures that would be applied to 
minimized effects of the higher-power sources would further reduce or 
eliminate any minor effects of the chirp.

Estimated Take by Incidental Harassment

    All anticipated takes would be ``takes by harassment'', involving 
temporary changes in behavior. The proposed mitigation measures are 
expected to minimize the possibility of injurious takes. (However, as 
noted earlier, there is no specific information demonstrating that 
injurious ``takes'' would occur even in the absence of the planned 
mitigation measures.) In the sections below, we describe methods to 
estimate ``take by harassment'', and present estimates of the numbers 
of marine mammals that might be affected during the proposed seismic 
survey in the northeast Pacific Ocean. The estimates are based on data 
concerning marine mammal densities (numbers per unit area) obtained 
during surveys off Oregon and Washington during 1996 and 2001 by NMFS 
Southwest Fisheries Science Center (SWFSC) and estimates of the size of 
the area where effects potentially could occur.
    The following estimates are based on a consideration of the number 
of marine mammals that might be disturbed appreciably by operations 
with the two GI guns to be used during approximately 1275 line-km of 
surveys off the coast of Oregon in the northeastern Pacific Ocean. The 
anticipated radii of influence of the echosounders are less than those 
for the GI guns. It is assumed that, during simultaneous operations of 
the GI guns and echosounders, any marine mammals close enough to be 
affected by the echosounders would already be affected by the airgun. 
However, whether or not the GI guns are operating simultaneously with 
the echosounders, marine mammals are expected to exhibit no more than 
short-term and inconsequential responses to the echosounders, given 
their characteristics (e.g., narrow downward-directed beam) and other 
considerations described previously. Therefore, no additional allowance 
is included for animals that might be affected by the echosounders.
    Extensive systematic aircraft- and ship-based surveys have been 
conducted for marine mammals offshore of Oregon and Washington (Bonnell 
et al., 1992; Green et al., 1992, 1993; Barlow, 1997, 2003; Barlow and 
Taylor, 2001; Calambokidis and Barlow, 2004; Barlow and Forney, 2007). 
The most comprehensive and recent density data available for cetacean 
species off slope and offshore waters of Oregon are from the 1996 and 
2001 NMFS/SWFSC ``ORCAWALE'' or ``CSCAPE'' ship surveys as synthesized 
by Barlow and Forney (2007). The surveys were conducted up to 
approximately 550 km (342 mi) offshore from June or July to early 
November or December. Systematic, offshore, at-sea survey data for 
pinnipeds are more limited. The most comprehensive studies are reported 
by Bonnell et al. (1992) and Green et al. (1993) based on systematic 
aerial surveys conducted in 1989 1990 and 1992, primarily from coastal 
to

[[Page 30087]]

slope waters with some offshore effort as well.
    Oceanographic conditions, including occasional El Nino and La Nina 
events, influence the distribution and numbers of marine mammals 
present in the northeastern Pacific Ocean, including Oregon, resulting 
in considerable year-to-year variation in the distribution and 
abundance of many marine mammal species (Forney and Barlow, 1998; 
Buchanan et al., 2001; Escorza-Trevino, 2002; Ferrero et al., 2002; 
Philbrick et al., 2003). Thus, for some species the densities derived 
from recent surveys may not be representative of the densities that 
will be encountered during the proposed seismic survey.
    Table 3 in UTIG's application gives the average and maximum 
densities for each species or species group of marine mammals reported 
off Oregon and Washington (and used to calculate the take estimates in 
Table 1 here), corrected for effort, based on the densities reported 
for the 1996, 2001, and 2005 surveys (Barlow, 2003). The densities from 
these studies had been corrected, by the original authors, for both 
detectability bias and availability bias. Detectability bias is 
associated with diminishing sightability with increasing lateral 
distance from the trackline [f(0)]. Availability bias refers to the 
fact that there is less-than-100 percent probability of sighting an 
animal that is present along the survey trackline, and it is measured 
by g(0). Table 3 also includes mean density information for three of 
the five pinnipeds species that occur off Oregon and Washington and 
mean and maximum densities for one of those species, from Bonnell et 
al. (1992). Densities were not calculated for the other two species 
because of the small number of sightings on systematic transect 
surveys.
    It should be noted that the following estimates of ``takes by 
harassment'' assume that the seismic surveys will be undertaken and 
completed; in fact, the planned number of line-kms has been increased 
by 25 percent to accommodate lines that may need to be repeated, 
equipment testing, etc. As is typical on offshore ship surveys, 
inclement weather, and equipment malfunctions may cause delays and may 
limit the number of useful line-kms of seismic operations that can be 
undertaken. Furthermore, any marine mammal sightings within or near the 
designated safety zones will result in the shut down of seismic 
operations as a mitigation measure. Thus, the following estimates of 
the numbers of marine mammals potentially exposed to 160 dB sounds are 
precautionary, and probably overestimate the actual numbers of marine 
mammals that might be involved. These estimates assume that there will 
be no weather, equipment, or mitigation delays, which is unlikely.
    There is some uncertainty about the representativeness of the data 
and the assumptions used in the take calculations. However, the 
approach used here is believed to be the best available approach. Also, 
to provide some allowance for the uncertainties, ``maximum estimates'' 
as well as ``best estimates'' of the numbers potentially affected have 
been derived. Best and maximum estimates are based on the average and 
maximum estimates of densities reported by Barlow and Forney (2007) and 
Bonnel et al. (1992) described above. The estimated numbers of 
potential individuals exposed are based on the 160-dB re 1 microPa rms 
criterion for all cetaceans and pinnipeds, and also based on the 170-dB 
criterion for delphinids and pinnipeds only. It is assumed that marine 
mammals exposed to airgun sounds this strong might change their 
behavior sufficiently to be considered ``take by harassment''. UTIG has 
requested authorization for the take of the maximum estimates and NMFS 
has analyzed the maximum estimate for it's effect on the species or 
stock.
    The number of different individuals that may be exposed to GI-gun 
sounds with received levels [gteqt]160 dB re 1 microPa (rms) on one or 
more occasions can be estimated by considering the total marine area 
that would be within the 160 dB radius around the operating GI guns on 
at least one occasion. The proposed seismic lines do not run parallel 
to each other in close proximity, which minimizes the number of times 
an individual mammal may be exposed during the survey. However, it is 
unlikely that a particular animal would stay in the area during the 
entire survey. The best estimates in this section are based on the 
average of the densities from the 1996, 2001, and 2005 NMFS surveys, 
and maximum estimates are based on the higher estimate. Table 4 in 
UTIG's application (and used to calculate the take estimates in Table 1 
here) shows the best and maximum estimates of the number of marine 
mammals that could potentially be affected during the seismic survey.
    The number of different individuals potentially exposed to received 
levels [gteqt]160 dB re 1 microPa (rms) was calculated by multiplying:
     The expected species density, either ``mean'' (i.e., best 
estimate) or ``maximum, `` times
     The anticipated minimum area to be ensonified to that 
level during the GI guns operations including overlap (exposures), or
     The anticipated minimum area to be ensonified to that 
level during GI gun operations excluding overlap (individuals).
    The area expected to be ensonified was determined by entering the 
planned survey lines into a MapInfo Geographic Information System 
(GIS), using the GIS to identify the relevant areas by ``drawing'' the 
applicable 160 dB or 170 dB buffer around each seismic line and then 
calculating the total area within the buffers. Areas where overlap 
occurred (because of intersecting lines) were included only once to 
determine the minimum area expected to be ensonified.
    Applying the approach described above, approximately 189 km\2\ 
would be within the 160 dB isopleth on one or more occasions during the 
survey, whereas approximately 1,391 km\2\ is the area ensonified when 
overlap is included. Because this approach does not allow for turnover 
in the mammal populations in the study area during the course of the 
survey, the actual number of individuals exposed may be underestimated. 
However, this will be offset to some degree by the fact that the 160 dB 
(and other) distances assumed here actually apply to a pair of slightly 
larger GI guns to be used in the project. In addition, the approach 
assumes that no cetaceans will move away or toward the trackline as the 
Thompson approaches in response to increasing sound levels prior to the 
time the levels reach 160 dB. Another way of interpreting the estimates 
that follow is that they represent the number of individuals that are 
expected (in the absence of a seismic program) to occur in the waters 
that will be exposed to [gteqt]160 dB re 1 microPa (rms).
    The ``best estimate'' of the number of individual cetaceans that 
might be exposed to seismic sounds with received levels [gteqt]160 dB 
re 1 microPa (rms) during the surveys is 42 (Table 4 in UTIG's 
application). The total does not include any endangered or beaked 
whales. Dall's porpoise is estimated to be the most common species 
exposed; the best estimates for those species are 28 (Table 4 in UTIG 
application). The best estimate of the number of exposures of cetaceans 
to seismic sounds with received levels [gteqt]160 dB re 1 microPa (rms) 
during the survey is 536, including 1 humpback whale, 1 fin whale, and 
2 sperm whales. Dall's porpoise was exposed most frequently, with a 
best estimate of 209 exposures.
    The ``maximum estimate'' column in Table 4 of UTIG's application 
shows an estimated total of 85 cetaceans that

[[Page 30088]]

might be exposed to seismic sounds [gteqt]160 dB during the surveys. In 
most cases, those estimates are based on survey data, as described 
above. For endangered species, the 'maximum estimate' is the mean group 
size (from Barlow and Forney, in press) in cases where the calculated 
maximum number of individuals exposed was between 0.05 and the mean 
group size (humpback, fin, blue, and sperm whales). The numbers for 
which take authorization is requested, given in the far right column of 
Table 4 in UTIG's application are the maximum estimates. Based on the 
abundance numbers given in UTIG's application and Table 1 here for non-
listed cetacean species, NMFS believes that the estimated take numbers 
are small relative to the stock sizes for these species (i.e., no more 
than 0.4 percent of any species).
    The best and maximum estimates of the numbers of exposures to 
[gteqt]170 dB for all delphinids during the surveys are 9 and 13, 
respectively. Corresponding estimates for Dall's porpoise are 17 and 
29. The estimates are based on the predicted 170 dB radii around the GI 
guns to be used during the study and are considered to be more 
realistic estimates of the number of individual delphinids and Dall's 
porpoises that may be affected.
    Only two of the five pinniped species discussed in Section III of 
UTIG's application the northern fur seal and the northern elephant seal 
are likely to occur in the offshore and slope waters; the other three 
species of pinnipeds known to occur regularly off Oregon and Washington 
the California sea lion, Steller sea lion, and harbor seal are 
infrequent there. This conclusion is based on results of extensive 
aerial surveys conducted from the coast to offshore waters of Oregon 
and Washington (Bonnell et al., 1992; Green et al., 1993; Buchanan et 
al., 2001; Carretta et al., 2007). However, the available density data 
are probably not truly representative of densities that could be 
encountered during surveys, as the data were averaged over a number of 
months and over coastal, shelf, slope, and offshore waters. These 
factors strongly influence the densities of these pinnipeds at sea, as 
all pinnipeds off Oregon and Washington exhibit seasonal and/or inshore 
offshore movements largely related to breeding and feeding (Bonnell et 
al., 1992; Buchanan et al., 2001; Carretta et al., 2007).
    Most pinnipeds, like delphinids, seem to be less sensitive to 
airgun sounds than are mysticetes. Thus, the numbers of pinnipeds 
likely to be exposed to received levels [gteqt]170 dB re 1 microPa 
(rms) were also calculated, based on the estimated 170-dB radii in 
Table 1 of UTIG's application. For operations in deep water, the 
estimated 160 and 170 dB radii are very likely over-estimates of the 
actual 160- and 170-dB distances (Tolstoy et al., 2004a,b). Thus, the 
resulting estimates of the numbers of pinnipeds exposed to such levels 
may be overestimated.
    The methods described previously for cetaceans were also used to 
calculate exposure numbers for the one pinniped species likely to be in 
the survey area and whose densities were estimated by Bonnell et al. 
(1992). Based on the ``best'' densities, two northern fur seals are 
considered likely to be exposed to GI gun sounds [gteqt]160 dB re 1 
microPa (rms). The ``Maxim Estimate'' column in Table 4 of UTIG's 
application shows an estimated 19 northern fur seals that could be 
exposed to GI airgun sounds [gteqt]160-dB or [gteqt]170dB re 1 microPa 
(rms), respectively, during the survey. Also included are low maximum 
estimates for the northern elephant seals, a species that likely would 
be present but whose density was not calculated because of the small 
number of sightings on systematic transect surveys. The numbers of 
which ``take authorization'' is requested, given in the far right 
column of Table 4 of UTIG's application, are based on the maximum 160 
dB estimates.
    The proposed UTIG seismic survey in the northeastern Pacific Ocean 
involves towing two GI guns that introduce pulsed sounds into the 
ocean, as well as echosounder operations. A towed P-Cable system will 
be deployed to receive and record the returning signals. Routine vessel 
operations, other than the proposed GI gun operations, are 
conventionally assumed not to affect marine mammals sufficiently to 
constitute ``taking.'' No ``taking'' of marine mammals is expected in 
association with operations of the echosounders given the 
considerations discussed in section IV(1)(b) of UTIGS's application, 
i.e., sounds are beamed downward, the beam is narrow, and the pulses 
are extremely short.
    Strong avoidance reactions by several species of mysticetes to 
seismic vessels have been observed at ranges up to 6-8 km (3.7-5 mi) 
and occasionally as far as 20-30 km (12.4-18.6 mi) from the source 
vessel when much larger airgun arrays have been used. However, 
reactions at the longer distances appear to be atypical of most species 
and situations and in any case apply to larger airgun systems than will 
be used in this project. If mysticetes are encountered, the numbers 
estimated to occur within the 160 dB isopleth in the survey area are 
expected to be very low. In addition, the estimated numbers presented 
in Table 4 of UTIG's application are considered overestimates of actual 
numbers because the estimated 160 and 170 dB radii used here are 
probably overestimates of the actual 160 and 170 dB radii at deep-water 
locations such as the present study areas (Tolstoy et al., 2004a,b). In 
addition, the radii were based on a larger airgun source than the one 
proposed for use during the present survey.
    Odontocete reactions to seismic pulses, or at least the reactions 
of delphinids and Dall's porpoises are expected to extend to lesser 
distances than are those of mysticetes. Odontocete low-frequency 
hearing is less sensitive than that of mysticetes, and delphinids and 
Dall's porpoises are often seen from seismic vessels. In fact, there 
are documented instances of dolphins and Dall's porpoises approaching 
active seismic vessels. However, delphinids and porpoises (along with 
other cetaceans) sometimes show avoidance responses and/or other 
changes in behavior when near operating seismic vessels.
    Taking into account the mitigation measures that are proposed in 
UTIG's application, effects on cetaceans are generally expected to be 
limited to avoidance of the area around the seismic operation and 
short-term changes in behavior, falling within the MMPA definition of 
``Level B harassment.'' Furthermore, the estimated numbers of animals 
potentially exposed to sound levels sufficient to cause appreciable 
disturbance are very low percentages of the regional population sizes. 
The best estimates of the numbers of individual cetaceans (33 for all 
species combined) that would be exposed to sounds [gteqt]160 dB re 1 
microPa (rms) during the proposed survey represent, on a species-by-
species basis, no more than 0.11 pertcent of the regional populations 
(see Table 4 of UTIG's application). Dall's porpoise is the cetacean 
species with the highest estimated number of individuals exposed to 
[gteqt]160 dB.
    Varying estimates of the numbers of marine mammals that might be 
exposed to the GI guns sounds during the proposed summer 2008 seismic 
survey in the northeastern Pacific Ocean have been presented, depending 
on the specific exposure criterion ([gteqt]160 or [gteqt]170 dB) and 
density criterion used (best or maximum). The request ``take 
authorization'' for each species is based on the estimated maximum 
number of individuals that might be exposed to [gteqt]160 re 1 microPa 
(rms). That figure likely

[[Page 30089]]

overestimates (in most cases by a large margin) the actual number of 
animals that will be exposed to and will react to the seismic sounds. 
The reasons for that conclusion are outlined above. The relatively 
short-term exposures are unlikely to result in any long-term negative 
consequences for the individuals or their populations.
    The many cases of apparent tolerance by cetaceans of seismic 
exploration, vessel traffic, and some other human activities show that 
co-existence is possible. Mitigation measures such as controlled speed, 
course alteration, look outs, non-pursuit, and shut downs when marine 
mammals are seen within defined ranges should further reduce short-term 
reactions, and minimize any effects on hearing sensitivity. In all 
cases, the effects are expected to be short-term, with no lasting 
biological consequence.
    Only two of the five pinniped species discussed in Section III of 
UTIG's application, the northern fur seal and northern elephant seal, 
are likely to occur in the offshore and slope waters of the study area. 
A best estimate of a single northern fur seal could be exposed to 
airgun sounds with received levels [gteqt]160 dB re 1 microPa (rms). 
The numbers for which ``take authorization'' is requested are given in 
the far right column of Table 4 of UTIG's application. As for 
cetaceans, the estimated numbers of pinnipeds that may be exposed to 
received levels [gteqt]160 dB are probably overestimates of the actual 
numbers that will be affected, and are very small proportions of the 
respective population sizes.

Potential Effects on Habitat

    The proposed seismic surveys will not result in any permanent 
impact on habitats used by marine mammals or to the food sources they 
use. The main impact issue associated with the proposed activity will 
be temporarily elevated noise levels and the associated direct effects 
on marine mammals, as discussed above.
    One of the reasons for the adoption of airguns as the standard 
energy source for marine seismic surveys was that, unlike explosives, 
they have not been associated with any appreciable fish kills. However, 
the existing body of information relating to the impacts of seismic 
surveys on marine fish (see Appendix B of UTIG's application) and 
invertebrate species is very limited. The various types of potential 
effects of exposure to seismic on fish and invertebrates can be 
considered in three categories: (1) pathological, (2) physiological, 
and (3) behavioral. Pathological effects include lethal and temporary 
or permanent sub-lethal damage to the animals, physiological effects 
include temporary and permanent primary and secondary stress responses, 
such as changes in levels of enzymes and proteins. Behavioral effects 
refer to temporary and categories are interrelated in complex ways. For 
example, it is possible that certain physiological and behavioral 
changes could potentially lead to the ultimate pathological effect on 
individual animals (i.e., mortality).
    The specific received levels at which permanent adverse effects to 
fish potentially could occur are little studies and largely unknown. 
Furthermore, available information on the impacts of seismic surveys on 
marine fish and invertebrates is from studies of individuals or 
portions of a population; there have been no studies at the population 
scale. Thus, available information provides limited insight on possible 
real world effects at the ocean or population scale. This makes drawing 
conclusions about impacts on fish problematic because ultimately, the 
most important aspect of potential impacts relates to how exposure to 
seismic survey sound affects marine fish populations and their 
viability, including their availability to fisheries.
    The following sections provide an general overview of the available 
information that exists on the effects of exposure to seismic surveys 
and other anthropogenic sound as relevant to fish and invertebrates. 
The information comprises results from scientific studies of varying 
degrees of soundness and some anecdotal information.
    Pathological Effects - The potential for pathological damage to 
hearing structures in fish depends on the energy level of the received 
sound and the physiology and hearing capability of the species in 
question (see Appendix B of UTIG's application). For a given sound to 
result in hearing loss, the sound must exceed, by some specific amount, 
the hearing threshold of the fish for that sound (Popper, 2005). The 
consequences of temporary or permanent hearing loss in individual fish 
on a fish population is unknown; however, it likely depends on the 
number of individuals affected and whether critical behaviors involving 
sound (e.g., predator avoidance, prey capture, orientation and 
navigation, reproduction, etc.) are adversely affected.
    Little is known about the mechanisms and characteristics of damage 
to fish that may be inflicted by exposure to seismic survey sounds. Few 
data have been presented in the peer-reviewed scientific literature. 
There are two valid papers with proper experimental methods, controls, 
and careful pathological investigation implicating sounds produced by 
actual seismic survey airguns with adverse anatomical effects. One such 
study indicated anatomical damage and the second indicated TTS in fish 
hearing. McCauley et al. (2003) found that exposure to airgun sound 
caused observable anatomical damage to the auditory maculae of ``pink 
snapper'' (Pagrus auratus). This damage in the ears had not been 
repaired in fish sacrificed and examined almost two months after 
exposure. On the other hand, Popper et al. (2005) documented only TTS 
(as determined by auditory brainstem response) in two of three fishes 
from the Mackenzie River Delta. This study found that broad whitefish 
(Coreogonus nasus) that received a sound exposure level of 177 dB re 1 
microPa\2\s showed no hearing loss. During both studies, the 
repetitive exposure to sound was greater than would have occurred 
during a typical seismic survey. However, the substantial low-frequency 
energy produced by the airgun arrays [less than approximately 400 Hz in 
the study by McCauley et al. (2003) and less than approximately 200 Hz 
in Popper et al. (2005)] likely did not propagate to the fish because 
the water in the study areas was very shallow (approximately 9 m, 29.5 
ft, in the former case and <2 m, 6.6 ft, in the latter). Water depth 
sets a lower limit on the lowest sound frequency that will propagate 
(the ``cutoff frequency'') at about one-quarter wavelength (Urick, 
1983; Rogers and Cox, 1988).
    In water, acute injury and death of organisms exposed to seismic 
energy depends primarily on two features of the sound source: (1) the 
received peak pressure, and (2) the time required for the pressure to 
rise and decay (Hubbs and Rechnitzer, 1952; Wardle et al., 2001). 
Generally, the higher the received pressure and the less time it takes 
for the pressure to rise and decay, the greater the chance of acute 
pathological effects. Considering the peak pressure and rise/decay time 
characteristics of seismic airgun arrays used today, the pathological 
zone for fish and invertebrates would be expected to be within a few 
meters of the seismic source (Buchanan et al., 2004). For the proposed 
survey, any injurious effects on fish would be limited to very short 
distances, especially considering the small source planned for use in 
this project (two 40-60-in\3\ GI guns). Numerous other studies provide 
examples of no fish mortality upon exposure to seismic sources (Falk 
and

[[Page 30090]]

Lawrence, 1973; Holliday et al., 1987; La Bella et al., 1996; Santulli 
et al., 1999; McCauley et al., 2000a, 2000b, 2003; Bjarti, 2002; Hassel 
et al., 2003; Popper et al., 2005).
    Except for these two studies, at least with airgun-generated sound 
treatments, most contributions rely on rather subjective assays such as 
fish ``alarm'' or ``startle response'' or changes in catch rates by 
fishers. These observations are important in that they attempt to use 
the levels of exposures that are likely to be encountered by most free-
ranging fish in actual survey areas. However, the associated sound 
stimuli are often poorly described, and the biological assays are 
varied (Hastings and Popper, 2005).
    Some studies have reported that mortality of fish, fish eggs, or 
larvae can occur close to seismic sources (Kostyuchenko, 1973; Dalen 
and Knutsen, 1986; Booman et al., 1996; Dalen et al., 1996). Some of 
the reports claimed seismic effects from treatments quite different 
from actual seismic survey sounds or even reasonable surrogates. Saetre 
and Ona (1996) applied a ``worst-case scenario'' mathematical model to 
investigate the effects of seismic energy on fish eggs and larvae and 
concluded that mortality rates caused by exposure to seismic are so low 
compared to natural mortality that the impact of seismic surveying on 
recruitment to a fish stock must be regarded as insignificant.Some 
studies have reported, some equivocally, that mortality of fish, fish 
eggs, or larvae can occur close to seismic sources (Kostyuchenko, 1973; 
Dalen and Knutsen, 1986; Booman et al., 1996; Dalen et al., 1996). Some 
of the reports claimed seismic effects from treatments quite different 
from actual seismic survey sounds or even reasonable surrogates 
suggested that seismic survey sound has a limited pathological impact 
on early developmental stages of crustaceans (Pearson et al., 1994; 
Christian et al., 2003; DFO, 2004). However, the impacts appear to be 
either temporary or insignificant compared to what occurs under natural 
conditions. Controlled field experiments on adult crustaceans 
(Christian et al., 2003, 2004; DFO, 2004) and adult cephalopods 
(McCauley et al., 2000a,b) exposed to seismic survey sound have not 
resulted in any significant pathological impacts on the animals. It has 
been suggested that exposure to commercial seismic survey activities 
has injured giant squid (Guerra et al., 2004), but there is no evidence 
to support such claims.
    Physiological Effects - Physiological effects refer to cellular 
and/or biochemical responses of fish to acoustic stress. Such stress 
potentially could affect fish populations by increasing mortality or 
reducing reproductive success. Primary and secondary stress responses 
of fish after exposure to seismic survey sound appear to be temporary 
in all studies done to date (Sverdrup et al., 1994; McCauley et al., 
2000a, 2000b). The periods necessary for the biochemical changes to 
return to normal are variable and depend on numerous aspects of the 
biology of the species and of the sound stimulus (see Appendix B of 
UTIG's application for more information on the effects of airgun sounds 
on marine fish). Such stress could potentially affect animal 
populations by reducing reproductive capacity and adult abundance and 
increasing mortality.
    Behavioral Effects - Behavioral effects include changes in the 
distribution, migration, mating, and catchability of fish populations. 
Studies investigating the possible effects of sound (including seismic 
sound) on fish behavior have been conducted on both uncaged and caged 
individuals (e.g., Chapman and Hawkings, 1969; Pearson et al., 1992; 
Santulli et al., 1999, Wardle et al., 2001, Hassel et al., 2003). 
Typically, in these studies fish exhibited sharp ``startle'' response 
at the onset of a sound followed by habituation and a return to normal 
behavior after the sound ceased.
    There is general concern about potential adverse effects of seismic 
operations on fisheries, namely a reduction in the ``catchability'' of 
fish involved in fisheries. Although reduced catch rates have been 
observed in some marine fisheries during seismic testing, in a number 
of cases the findings are confounded by other sources of disturbance 
(Dalen and Raknes, 1985; Dalen and Knutsen, 1986; L kkeborg, 1991; 
Skalski et al., 1992; Engas et al., 1996). In other airgun experiments, 
there was no change in CPUE of fish when airgun pulses were emitted, 
particularly in the immediate vicinity of the seismic survey (Pickett 
et al., 1994; La Bella et al., 1996). For some species, reductions in 
catch may have resulted from a change in behavior of the fish, e.g., a 
change in vertical or horizontal distribution, as reported in the 
Slotte et al. (2004).
    Summary of Physical (Pathological and Physiological) Effects - As 
indicated in the preceding general discussion, there is a relative lack 
of knowledge about the potential physical (pathological and 
physiological) effects of seismic energy on marine fish and 
invertebrates. Available data suggest that there may be physical 
impacts on egg, larval, juvenile, and adult stages at very close range. 
Considering typical source levels associated with commercial seismic 
arrays, close proximity to the source would result in exposure to very 
high energy levels. Again, this study will employ a sound source that 
will generate low energy levels. Whereas egg and larval stages are not 
able to escape such exposures, juveniles and adults most likely would 
avoid it. In the case of eggs and larvae, it is likely that the numbers 
adversely affected by such exposure would not be that different from 
those succumbing to natural mortality. Limited data regarding 
physiological impacts on fish and invertebrates indicate that these 
impacts are short term and are most apparent after exposure at close 
range.
    The proposed seismic program for 2008 is predicted to have 
negligible to low physical effects on the various life stages of fish 
and invertebrates for its relatively short duration (approximately 150 
total hours at each of the three sites off the coast of Oregon) and 
approximately 975 km (606 mi) extent. Therefore, physical effects of 
the proposed program on the fish and invertebrates would be not 
significant.
    Behavioral Effects - Because of the apparent lack of serious 
pathological and physiological effects of seismic energy on marine fish 
and invertebrates, most concern now centers on the possible effects of 
exposure to seismic surveys on the distribution, migration patterns, 
mating, and catchability of fish. There is a need for more information 
on exactly what effects such sound sources might have on the detailed 
behavior patterns of fish and invertebrates at different ranges.
    Studies investigating the possible effects of seismic energy on 
fish and invertebrate behavior have been conducted on both uncaged and 
caged animals (Chapman and Hawkins, 1969; Pearson et al., 1992; 
Santulli et al., 1999; Wardle et al., 2001; Hassel et al., 2003). 
Typically, in these studies fish exhibited a sharp ``startle'' response 
at the onset of a sound followed by habituation and a return to normal 
behavior after the sound ceased.
    There is general concern about potential adverse effects of seismic 
operations on fisheries, namely a potential reduction in the 
``catchability'' of fish involved in fisheries. Although reduced catch 
rates have been observed in some marine fisheries during seismic 
testing, in a number of cases the findings are confounded by other 
sources of disturbance (Dalen and Raknes, 1985; Dalen and Knutsen, 
1986; L kkeborg, 1991; Skalski et al., 1992; Engas et al., 1996). In 
other airgun experiments, there was no change in

[[Page 30091]]

catch per unit effort of fish when airgun pulses were emitted, 
particularly in the immediate vicinity of the seismic survey (Pickett 
et al., 1994; La Bella et al., 1996). For some species, reductions in 
catch may have resulted from a change in behavior of the fish (e.g., a 
change in vertical or horizontal distribution) as reported in Slotte et 
al. (2004).
    In general, any adverse effects on fish behavior or fisheries 
attributable to seismic testing may depend on the species in question 
and the nature of the fishery (season, duration, fishing method). They 
may also depend on the age of the fish, its motivational state, its 
size, and numerous other factors that are difficult, if not impossible, 
to quantify at this point, given such limited data on effects of 
airguns on fish, particularly under realistic at-sea conditions.
    In general, any adverse effects on fish behavior or fisheries 
attributable to seismic testing may depend on the species in question 
and the nature of the fishery (season, duration, fishing method). They 
may also depend on the age of the fish, its motivational state, its 
size, and numerous other factors that are difficult, if not impossible, 
to quantify at this point, given such limited data on effects of 
airguns on fish, particularly under realistic at-sea conditions.

Effects on Invertebrates

    The existing body of information on the impacts of seismic survey 
sound on marine invertebrates is very limited. However, there is some 
unpublished and very limited evidence of the potential for adverse 
effects on invertebrates, thereby justifying further discussion and 
analysis of this issue. Th three types of potential effects of exposure 
to seismic surveys on marine invertebrates are pathological, 
physiological, and behavioral. Based on the physical structure of their 
sensory organs, marine invertebrates appear to be specialized to 
respond to particle displacement components of an impinging sound field 
and not to the pressure component (Popper et al. 2001; see also 
Appendix C of UTIG's application).
    The only information available on the impacts of seismic surveys on 
marine invertebrates involves studies of individuals; there have been 
no studies at the population scale. Thus, available information 
provides limited insight on possible real world effects at the regional 
or ocean scale. The most important aspect of potential impacts concerns 
how exposure to seismic survey sound ultimately affects invertebrate 
populations and their viability, including availability to fisheries.
    The following sections provide a synopsis of available information 
on the effects of exposure to seismic survey sound on species of 
decapod crustaceans and cephalopods, the two taxonomic groups of 
invertebrates on which most such studies have been conducted. The 
available information is from studies with variable degrees of 
scientific soundness and from anecdotal information.
    Pathological Effects - In water, lethal and sub-lethal injury to 
organisms exposed to seismic survey sound could depend on at least two 
features of the sound source: (1) the received peak pressure, and (2) 
the time required for the pressure to rise and decay. Generally as 
received pressure increases, the period for the pressure to rise and 
decay decreases, and the chance of acute pathological effects 
increases. For the two GI guns planned for the proposed program, the 
pathological (mortality) zone for crustaceans and cephalopods is 
expected to be within a few metes of the seismic source; however, very 
few specific data are available on levels of seismic signals that might 
damage these animals. This premise is based on the peak pressure and 
rise/decay time characteristics of seismic airgun arrays currently in 
use around the world.
    Some studies have suggested that seismic survey sound has a limited 
pathological impact on early developmental stage of crustaceans 
(Pearson et al., 1994; Christian et al., 2003; DFO, 2004). However, the 
impacts appear to be either temporary or insignificant compared to what 
occurs under natural conditions. Controlled field experiments on adult 
crustaceans (Christian et al., 2003, 2004; DFO 2004) and adult 
cephalopods (McCauley et al., 2000a,b) exposed to seismic survey sound 
have not resulted in any significant pathological impacts on animals. 
It has been suggested that exposure to commercial seismic survey 
activities has injured giant squid (Guerra et al., 2003), but there is 
no evidence to support such claims.
    Physiological Effects - Physiological effects refer mainly to 
biochemical responses by marine invertebrates to acoustic stress. Such 
stress potentially cold affect invertebrate populations by increasing 
mortality or reducing reproductive success. Any primary and secondary 
stress responses (i.e. changes in haemolymph levels of enzymes, 
proteins, etc.) of crustaceans after exposure seismic survey sounds 
appear to be temporary (hours to days) in studies done to date (Payne 
et al., 2007). The periods necessary for these biochemical changes to 
return to normal are variable and depend on numerous aspects of the 
biology of the species and of the sound stimulus.
    Behavioral Effects - There is increasing interest in assessing the 
possible direct and indirect effects of seismic and other sounds on 
invertebrate behavior, particularly in relation to the consequences for 
fisheries. Changes in behavior could potentially affect such aspects as 
reproductive success, distribution, susceptibility to predation, and 
catchability by fisheries. Studies investigating the possible 
behavioral effects of exposure to seismic survey sound on crustaceans 
and cephalopods have been conducted on both uncaged and caged animals. 
In some cases, invertebrates exhibited startle responses (e.g., squid 
in McCauley et al., 2000a,b). In other cases, no behavioral impacts 
were noted (e.g., crustaceans in Christian et al., 2003, 2004; DFO, 
2004). Ther have been anecdotal reports of reduced catch rates of 
shrimp shortly after exposure to seismic survey; however, other studies 
have not observed any significant changes in shrimp catch rate 
(Andriguetto-Filho et al., 2005). Any adverse effects on crustacean and 
cephalopod behavior or fisheries attributable to seismic survey sound 
depend on the species in question and the nature of the fishery 
(season, duration, fishing method).
    During the proposed study, only a small fraction of the available 
habitat would be ensonified at any given time, and fish and 
invertebrate species would return to their pre-disturbance behavior 
once the seismic activity ceased. The proposed seismic program is 
predicted to have negligible to low behavioral effects on the various 
life stages of the fish and invertebrates during its duration (total of 
approximately 150 hours) and 975 km (606 mi) extent.
    Because of the reasons noted above and the nature of the proposed 
activities (small airgun and limited duration), the proposed operations 
are not expected to have any habitat-related effects that could cause 
significant or long-term consequences for individual marine mammals or 
their populations or stocks. Similarly, any effects to food sources are 
expected to be negligible.
    The effects of the proposed activity on marine mammal habitats and 
food resources are expected to be negligible, as described above. A 
small minority of the marine mammals that are present near the proposed 
activity may be temporarily displaced as much as a few kilometers by 
the planned activity. During the proposed survey, marine mammals will 
be distributed according to their habitat preferences, in shelf, slope, 
and pelagic waters.

[[Page 30092]]

Concentrations of marine mammals and/or marine mammal prey species are 
not expected to occur in or near the proposed study area, and that area 
does not appear to constitute an area of localized or critical feeding, 
breeding, or migration for any marine mammal species. The proposed 
activity is not expected to have any habitat-related effects that could 
cause significant or long-term consequences for individual marine 
mammals or their populations, because operations at the various sites 
will be limited in duration.

Proposed Monitoring

    Vessel-based marine mammal visual observers (MMVOs) will be aboard 
the seismic source vessel and will watch for marine mammals near the 
vessel during all daytime GI gun operations and during start-ups of the 
gun at night. MMVOs will also watch for marine mammals near the seismic 
vessel for at least 30 minutes prior to the start of GI gun operations 
after an extended shut down. When feasible, MMVOs will also make 
observations during daytime periods when the seismic system is not 
operating for comparison of sighting rates and behavior with vs. 
without GI guns operations. Based on MMVO observations, the GI guns 
will be shut down when marine mammals are observed within or about to 
enter a designated exclusion zone (EZ; safety radius). The EZ is a 
region in which a possibility exists of adverse effects on animal 
hearing or other physical effects.
    MMVOs will be appointed by the academic institution conducting the 
research cruise, with NMFS Office of Protected Resources concurrence. A 
total of three MMVOs are planned to be aboard the source vessel. At 
least one MMVO will monitor the EZ during daytime GI guns operations 
and any night-time startups. MMVOs will normally work in daytime shifts 
of 4 hours duration or less. The vessel crew will also be instructed to 
assist in detecting marine mammals.
    The Thompson will serve as the platform from which MMVOs will watch 
for marine mammals before and during the GI guns operations. Two 
locations are likely as observation stations onboard the Thompson. At 
one station on the bridge, the eye level will be approximately 13.8 m 
(45.3 ft) above sea level and the location will offer a good view 
around the vessel (approximately 310 degrees for one observer and a 
full 360 degrees when two observers are stationed at different vantage 
points). A second observation station is the 03 deck where the 
observer's eye level will be approximately 10.8 m (35.4 ft) above sea 
level. The 03 deck offers a view of 330[deg] for two observers.
    Standard equipment for MMVOs will be 7 x 50 reticle binoculars and 
optical range finders. At night, night-vision devices (NVDs) will be 
available. Vessel lights and/or NVDs are useful in sighting some marine 
mammals at the surface within a short distance from the ship (within 
the EZ for the two GI guns). The observers will be in wireless 
communication with ship's officers on the bridge and scientists in the 
vessel's operations laboratory, so they can advise promptly of the need 
for avoidance maneuvers or GI guns shut down.
    MMVOs will record data to estimate the numbers of marine mammals 
exposed to various received sound levels and to document any apparent 
disturbance reactions. Data will be used to estimate the numbers of 
mammals potentially ``taken'' by harassment (as defined in the MMPA). 
They will also provide the information needed to order a shutdown of 
the two GI guns when a marine mammal is within or near the EZ. When a 
mammal sighting is made, the following information about the sighting 
will be recorded:
    (1) Species, group size, age/size/sex categories (if determinable), 
behavior when first sighted and after initial sighting, heading (if 
consistent), bearing and distance from seismic vessel, sighting cue, 
apparent reaction to the GI gun or seismic vessel (e.g., none, 
avoidance, approach, paralleling, etc.), and behavioral pace.
    (2) Time, location, heading, speed, activity of the vessel 
(shooting or not), sea state, visibility, and sun glare.
    The data listed under (2) will also be recorded at the start and 
end of each observation watch and during a watch, whenever there is a 
change in one or more of the variables.
    All marine mammal observations and information regarding airgun 
operations will be recorded in a standardized format. Data accuracy 
will be verified by the MMVOs at sea, and preliminary reports will be 
prepared during the field program and summaries forwarded to the 
operating institution's shore facility and to NSF weekly or more 
frequently. MMVO observations will provide the following information:
    (1) The basis for decisions about shutting down the GI guns.
    (2) Information needed to estimate the number of marine mammals 
potentially ``taken by harassment.'' These data will be reported to 
NMFS and/or USFWS per terms of MMPA authorizations..
    (3) Data on the occurrence, distribution, and activities of marine 
mammals in the area where the seismic study is conducted.
    (4) Data on the behavior and movement patterns of marine mammals 
seen at times with and without seismic activity.

Mitigation

    Mitigation and monitoring measures proposed to be implemented for 
the proposed seismic survey have been developed and refined during 
previous SIO and L-DEO seismic studies and associated EAs, IHA 
applications, and IHAs. The mitigation and monitoring measures 
described herein represent a combination of the procedures required by 
past IHAs for other SIO and L-DEO projects. The measures are described 
in detail below.
    Mitigation measures that are proposed to be implemented include (1) 
vessel speed or course alteration, provided that doing so will not 
compromise operational safety requirements, (2) GI guns ramp up and 
shut down, and (3) minimizing approach to slopes and submarine canyons, 
if possible, because of sensitivity of beaked whales. Two other 
standard mitigation measures airgun array power down are not possible 
because only two, low-volume GI guns will be used for the surveys.
    Speed or Course Alteration - If a marine mammal is detected outside 
the EZ but is likely to enter it based on relative movement of the 
vessel and the animal, then if safety requirements allow, the vessel 
speed and/or direct course will be adjusted to minimize the likelihood 
of the animal entering the EZ. Major course and speed adjustments are 
often impractical when towing long seismic streamers and large source 
arrays, but are possible in this case because only two GI guns and a 
short P-Cable system with streamers will be used. If the animal appears 
likely to enter the EZ, further mitigative actions will be taken, i.e. 
either further course alterations or shut down of the airgun.
    Ramp-up Procedures - A ``ramp-up'' procedure will be followed when 
the airguns begin operating after a period without airgun operations. 
The two GI guns will be added in sequence 5 minutes apart. During ramp-
up procedures, the safety radius for the two GI guns will be 
maintained.
    Shut-down Procedures - If a marine mammal is within or about to 
enter the EZ for the two GI guns, it will be shut down immediately. 
Following a shut down, the GI guns activity will not resume until the 
marine mammal is outside the EZ for the full array. The animal will be 
considered to have cleared the EZ if it: (1) is visually observed to 
have left the EZ; (2) has not

[[Page 30093]]

been seen within the EZ for 10 minutes in the case of small odontocetes 
and pinnipeds; or (3) has not been seen within the EZ for 15 minutes in 
the case of mysticetes and large odontocetes, including sperm, pygmy 
sperm, dwarf sperm, and beaked whales.
    The 10- and 15-min periods specified in (2) and (3), above, are 
shorter than would be used in a large-source project given the small 
180 and 190 dB (rms) radii for the two GI guns. GI gun operations will 
be able to resume following a shut-down during either the day or night, 
as the relatively small exclusion zone(s) will normally be visible even 
at night (see section VIII of UTIG's application).
    Minimize Approach to Slopes and Submarine Canyons - Although 
sensitivity of beaked whales to airguns is not specifically known, they 
appear to be sensitive to other sound sources (e.g., mid-frequency 
sonar; see section IV of UTIG's application). Beaked whales tend to 
concentrate in continental slope areas, and in areas where there are 
submarine canyons. Avoidance of airgun operations over or near 
submarine canyons where practicable has become a standard mitigation 
measure, but there are no submarine canyons within or near the study 
area. Also, airgun operations are not planned over slope sites during 
the proposed survey.

Reporting

    A report will be submitted to NMFS within 90 days after the end of 
the cruise. The report will describe the operations that were conducted 
and sightings of the marine mammals that were detected near the 
operations. The report will be submitted to NMFS, providing full 
documentation of methods, results, and interpretation pertaining to all 
monitoring. The 90-day report will summarize the dates and locations of 
seismic operations, all marine mammal and turtle sightings (dates, 
times, locations, activities, associated seismic survey activities). 
The report will also include estimates of the amount and nature of 
potential ``take'' of marine mammals by harassment or in other ways.

ESA

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

National Environmental Policy Act (NEPA)

    NSF prepared an Environmental Assessment (EA) of a Planned Low-
Energy Marine Seismic Survey by the Scripps Institution of Oceanography 
in the Northeast Pacific Ocean, September 2007. NMFS adopted NSF's 2007 
EA and will conducted a separate NEPA analysis and prepare a 
Supplemental EA, prior to making a determination on the issuance of the 
IHA.

Preliminary Determinations

    NMFS has preliminarily determined that the impact of conducting the 
seismic survey in the northeast Pacific Ocean may result, at worst, in 
a temporary modification in behavior (Level B Harassment) of small 
numbers of ten species of marine mammals. Further, this activity is 
expected to result in a negligible impact on the affected species or 
stocks. The provision requiring that the activity not have an 
unmitigable adverse impact on the availability of the affected species 
or stock for subsistence uses does not apply to this proposed action as 
there are no subsistence users within the geographic area of the 
proposed project.
     For reasons stated previously in this document, this determination 
is supported by: (1) the likelihood that, given sufficient notice 
through relatively slow ship speed, marine mammals are expected to move 
away from a noise source that is annoying prior to its becoming 
potentially injurious; (2) the fact that marine mammals would have to 
be closer than either 104 m (341.1 ft) in intermediate depths or 69 m 
(226.3 ft) in deep water from the vessel to be exposed to levels of 
sound (180 dB) believed to have even a minimal chance of causing TTS; 
and (3) the likelihood that marine mammal detection ability by trained 
observers is high at that short distance from the vessel. As a result, 
no take by injury or death is anticipated and the potential for 
temporary or permanent hearing impairment is very low and will be 
avoided through the incorporation of the proposed mitigation measures.
    While the number of potential incidental harassment takes will 
depend on the distribution and abundance of marine mammals in the 
vicinity of the survey activity, the number of potential harassment 
takings is estimated to be small, less than a few percent of any of the 
estimated population sizes, and has been mitigated to the lowest level 
practicable through incorporation of the measures mentioned previously 
in this document.

Proposed Authorization

    As a result of these preliminary determinations, NMFS proposes to 
issue an IHA to UTIG for conducting a low-energy seismic survey in the 
northeastern Pacific Ocean during June-July, 2008, provided the 
previously mentioned mitigation, monitoring, and reporting requirements 
are incorporated.

    Dated: May 16, 2008.
James H. Lecky,
Director, Office of Protected Resources, National Marine Fisheries 
Service.
[FR Doc. E8-11546 Filed 5-22-08; 8:45 am]
BILLING CODE 3510-22-S