[Federal Register Volume 74, Number 88 (Friday, May 8, 2009)]
[Notices]
[Pages 21631-21648]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E9-10821]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

RIN 0648-XI63


Incidental Takes of Marine Mammals During Specified Activities; 
Marine Geophysical Survey in the Northeast Pacific Ocean, August - 
October 2009

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 the Lamont-Doherty 
Earth Observatory (L-DEO), a part of Columbia University, for an 
Incidental Harassment Authorization (IHA) to take small numbers of 
marine mammals, by harassment, incidental to conducting a seismic 
survey in the northeast Pacific Ocean. Pursuant to the Marine Mammal 
Protection Act (MMPA), NMFS requests comments on its proposal to 
authorize L-DEO to take, by Level B harassment only, small numbers of 
marine mammals incidental to conducting a marine seismic survey during 
August through October, 2009.

DATES:  Comments and information must be received no later than June 8, 
2009.

ADDRESSES:  Comments on the application should be addressed to Michael 
Payne, Chief, Permits, Conservation and Education Division, Office of 
Protected Resources, National Marine Fisheries Service, 1315 East-West 
Highway, Silver Spring, MD 20910-3225. The mailbox address for 
providing email comments is <a href="/cdn-cgi/l/email-protection#adfdff9c839d9b999580f5e49b9eedc3c2cccc83cac2db"><span class="__cf_email__" data-cfemail="67373556495751535f4a3f2e5154270908060649000811">[email protected]</span></a>. Comments sent via 
e-mail, including all attachments, must not exceed a 10-megabyte file 
size.
    All comments received are a part of the public record and will 
generally be posted to http://www.nmfs.noaa.gov/pr/permits/incidental.htm#applications without change. All Personal Identifying 
Information (for example, name, address, etc.) voluntarily submitted by 
the commenter may be publicly accessible. Do not submit confidential 
business information or otherwise sensitive or protected information.
    A copy of the application containing a list of the references used 
in this document may be obtained by writing to the address specified 
above, telephoning the contact listed below (see FOR FURTHER 
INFORMATION CONTACT), or visiting the internet at: 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: Jeannine Cody or Howard Goldstein, 
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 (Secretary) to allow, upon request, 
the incidental, but not intentional, taking of marine mammals by United 
States citizens who engage in a specified activity (other than 
commercial fishing) within a specified geographical region if certain 
findings are made and either regulations are issued or, if the taking 
is limited to harassment, a notice of a proposed authorization is 
provided to the public for review.
    Authorization for incidental taking shall be granted if NMFS finds 
that the taking will have a negligible impact on the species or 
stock(s), will not have an unmitigable adverse impact on the 
availability of the species or stock(s) for subsistence uses, and if 
the permissible methods of taking and requirements pertaining to the 
mitigation, monitoring and reporting of such takings are set forth. 
NMFS has defined ``negligible impact'' in 50 CFR 216.103 as ''...an 
impact resulting from the specified activity that cannot be reasonably 
expected to, and is not reasonably likely to, adversely affect the 
species or stock through effects on annual rates of recruitment or 
survival.''
    Section 101(a)(5)(D) of the MMPA established an expedited process 
by which citizens of the United States can apply for an authorization 
to incidentally take small numbers of marine mammals by harassment. 
Except with respect to certain activities not pertinent here, the MMPA 
defines ``harassment'' as:
    any act of pursuit, torment, or annoyance which (i) has the 
potential to injure a marine mammal or marine mammal stock in the 
wild [ALevel A harassment@]; or (ii) has the potential to disturb a 
marine mammal or marine mammal stock in the wild by causing

[[Page 21632]]

disruption of behavioral patterns, including, but not limited to, 
migration, breathing, nursing, breeding, feeding, or sheltering 
[ALevel 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 
small numbers of marine mammals. Not later than 45 days after the close 
of the public comment period, if the Secretary makes the findings set 
forth in Section 101(a)(5)(D)(i), the Secretary shall issue or deny 
issuance of the authorization with appropriate conditions to meet the 
requirements of clause 101(a)(5)(D)(ii).

Summary of Request

    On February 11, 2009, NMFS received an application from L-DEO for 
the taking by Level B harassment only, of small numbers of 33 species 
of marine mammals incidental to conducting a marine seismic survey 
within the Exclusive Economic Zone (EEZ) of Canada in the northeast 
Pacific Ocean during August through October 2009. L-DEO, with research 
funding from the NSF, is conducting the geophysical data acquisition 
activities with onboard assistance by Drs. Toomey and Hooft from the 
University of Oregon, and Dr. Wilcock from the University of 
Washington.
    This survey, also known as the Endeavor Tomography (ETOMO) Study, 
will take place approximately 250 kilometers (km) (155 miles (mi)) 
southwest of Vancouver Island, British Columbia, within the Canadian 
Endeavour Marine Protected Area (MPA) along an 80-km- (50- mi-) long 
section of the Endeavour segment of the Juan de Fuca Ridge. The 
Endeavor MPA is a unique ecosystem consisting of hydrothermal vents and 
associated fauna. Canada officially designated the area as an MPA in 
March 2003. However, scientific research for the conservation, 
protection and understanding of the area is permissible under the 
Canadian Oceans Act of 1996. Regulations regarding this MPA can be 
found on the Department of Justice Canada website at: http://laws.justice.gc.ca/en/ShowFullDoc/cr/SOR-2003-87///en.
    The survey will obtain information on the sub-seafloor structure of 
volcanic and hydrothermal features that form as a result of movements 
of the Earth's plates; will obtain information on the three-dimensional 
(3-D) seismic structure of the crust and top-most mantle along an the 
Endeavour segment; and will define the distribution of magma beneath 
active volcanoes. Past studies using manned submersibles and remotely 
piloted vehicles have mapped the locations and characteristics of vent 
fields along this ridge segment. The ETOMO Study will extend that 
mapping beneath the seafloor and allow researchers to understand the 
dynamics of these systems.

Description of the Specified Activity

    The planned survey will involve one source vessel, the R/V Marcus 
G.Langseth (Langseth), a seismic research vessel owned by the NSF and 
operated by L-DEO. The proposed project is scheduled to commence on 
August 17, 2009, and scheduled to end on October 13, 2009. The vessel 
will depart Astoria, Oregon on August 17, 2009 for transit to the 
Endeavor MPA, between 47-48[deg] N. and 128-130[deg] W.
    To obtain high-resolution, 3-D structures of the area's magmatic 
systems and thermal structures, the Langseth will deploy a towed array 
of 36 airguns. The Langseth will also deploy 64 Ocean Bottom 
Seismometers (OBS). As the airgun array is towed along the survey 
lines, the OBSs will receive the returning acoustic signals and record 
them internally for later analysis. For the ETOMO study, the Langseth 
will not use a hydrophone streamer to receive geophysical data from the 
airgun array.
    The ETOMO study (e.g., equipment testing, startup, line changes, 
repeat coverage of any areas, and equipment recovery) will take place 
in deep (between 1200 and 3000 m, 3,280 feet (ft) and 1.8 mi) water and 
will require approximately 10 days to complete 12 transects of variable 
lengths totaling 1800 km of survey lines. Data acquisition will include 
approximately 240 hours of airgun operation. Please see L-DEO's 
application for more detailed information. The exact dates of the 
activities will depend on logistics, weather conditions, and the need 
to repeat some lines if data quality is substandard.

Vessel Specifications

    The Langseth is a seismic research vessel with a propulsion system 
designed to be as quiet as possible to avoid interference with the 
seismic signals. The vessel, which has a length of 71.5 m (235 feet 
(ft); a beam of 17.0 m (56 ft); a maximum draft of 5.9 m (19 ft); and a 
gross tonnage of 2925, can accommodate up to 55 people. The ship is 
powered by two Bergen BRG-6 diesel engines, each producing 3550 
horsepower (hp), which drive the two propellers directly. Each 
propeller has four blades, and the shaft typically rotates at 750 
revolutions per minute. The vessel also has an 800 hp bowthruster, 
which is not used during seismic acquisition. The operation speed 
during seismic acquisition is typically 7.4B9.3 km/hour (h) (4-5 
knots). When not towing seismic survey gear, the Langseth can cruise at 
20B24 km/h (11-13 knots). The Langseth has a range of 25,000 km (13,499 
nautical miles). The Langseth will also serve as the platform from 
which vessel-based marine mammal (and sea turtle) observers will watch 
for animals before and during airgun operations.

Acoustic Source Specifications

Seismic Airguns
    The full airgun array for the survey consists of 36 airguns (a 
mixture of Bolt 1500LL and Bolt 1900LLX airguns ranging in size from 40 
to 360 cubic inches (in\3\)), with a total volume of approximately 
6,600 in\3\ and a firing pressure of 1900 pounds per square inch (psi). 
The dominant frequency components range from two to 188 Hertz (Hz).
    The array configuration consists of four identical linear arrays or 
strings, with 10 airguns on each string; the first and last airguns 
will be spaced 16 m (52 ft) apart. For each operating string, nine 
airguns will be fired simultaneously, whereas the tenth is kept in 
reserve as a spare, to be turned on in case of failure of another 
airgun. The four airgun strings will be distributed across an 
approximate area of 24H16 m (79 x 52 ft) behind the Langseth and will 
be towed approximately 50 to 100 m (164-328 ft) behind the vessel at a 
tow-depth of 15 m (49.2 ft). The airgun array will fire every 250 m 
(105 seconds (s)) or 500 m (210 s) depending on which grid or line the 
Langseth surveys. During firing, a brief (approximately 0.1 s) pulse of 
sound is emitted. The airguns will be silent during the intervening 
periods.
Multibeam Echosounder
    The Langseth will operate a Simrad EM120 multibeam echosounder 
(MBES) simultaneously during airgun operations to map characteristics 
of the ocean floor. The hull-mounted MBES emits brief pulses of mid- or 
high-frequency (11.25-12.6 kHz) sound in a fanshaped beam that extends 
downward and to the sides of the ship. The beamwidth is 1 degree 
([deg]) fore-aft and 150[deg] athwartship. The maximum source level is 
242 dB re 1 microPa<bullet> m (root mean square (rms)). For deep-water 
operation, each Aping@ consists of nine successive fan-shaped 
transmissions, each 15 millisecond (ms) in duration and each 
ensonifying a sector that extends 1[deg] foreBaft. The nine successive

[[Page 21633]]

transmissions span an overall cross-track angular extent of about 
150[deg], with 16 ms gaps between the pulses for successive sectors. A 
receiver in the overlap area between two sectors would receive two 15-
ms pulses separated by a 16-ms gap. In shallower water, the pulse 
duration is reduced to 5 or 2 ms, and the number of transmit beams is 
also reduced. The ping interval varies with water depth, from 
approximately 5 s at 1000 m (3,281 ft) to 20 s at 4000 m (13,124 ft).
Sub-bottom Profiler
    The Langseth will operate a sub-bottom profiler (SBP) continuously 
throughout the cruise with the MBES. An SBP operates at mid- to high 
frequencies and is generally used simultaneously with an MBES to 
provide information about the sedimentary features and bottom 
topography. SBP pulses are directed downward at typical frequencies of 
approximately 3 18 kHz. However, the dominant frequency component of 
the SBP is 3.5 kHz which is directed downward in a narrow beam by a 
hull-mounted transducer on the vessel. The SBP output varies with water 
depth from 50 watts in shallow water to 800 watts in deep water and has 
a normal source output (downward) of 200 dB re 1 microPa m and a 
maximum source level output (downward) of 204 dB re 1 microPa m.
    The SBP used aboard the Langseth uses seven beams simultaneously, 
with a beam spacing of up to 15[deg] and a fan width up to 30[deg]. 
Pulse duration is 0.4 100 ms at intervals of 1 s; a common mode of 
operation is to broadcast five pulses at 1-s intervals followed by a 5-
s pause.

Characteristics of Airgun Pulses

    Discussion of the characteristics of airgun pulses has been 
provided in Appendix B of L-DEO=s application and in previous Federal 
Register notices (see 69 FR 31792, June 7, 2004; 71 FR 58790, October 
5, 2006; 72 FR 71625, December 18, 2007; 73 FR 52950, September 12, 
2008, or 73 FR 71606, November 25, 2008). Reviewers are referred to 
those documents for additional information.

Safety Radii

    Safety zones are areas defined by the radius of received sound 
levels believed to have the potential for at least temporary hearing 
impairment (HESS, 1999). The distance from the sound source at which an 
animal would be exposed to these different received sound levels may be 
estimated and is typically referred to as safety radii. These safety 
radii are specifically used to help NMFS estimate the number of marine 
mammals likely to be harassed by the proposed activity and in deciding 
how close a marine mammal may approach an operating sound source before 
the applicant will be required to power-down or shut down the sound 
source.
    During this study, all survey efforts will take place in deep 
(greater than 1000 m, 3820 ft) water. L-DEO has summarized the modeled 
safety radii for the planned airgun configuration in Table 1 which 
shows the predicted distances at which sound levels (190 decibels (dB), 
180 dB, and 160 dB) are expected to be received from the 36-airgun 
array and a single airgun operating in water greater than 1000 m (3,820 
ft) in depth.

Table 1. Predicted distances to which sound levels [gteqt]190, 180, and 160 dB re 1 microPa might be received in
 deep (>1000 m; 3280 ft) water from the 36-airgun array during the seismic survey, August September, 2009 (based
                                               on L-DEO modeling).
----------------------------------------------------------------------------------------------------------------
                                                                               Predicted RMS Distances (m)
             Source and Volume                     Tow Depth (m)       -----------------------------------------
                                                                           190 dB        180 dB        160 dB
----------------------------------------------------------------------------------------------------------------
Single Bolt airgun 40 in\3\                                   6-15\*\            12            40           385
4 strings 36 airguns 6600 in\3\                                     6           220           710          4670
                                                                    9           300           950          6000
                                                                   12           340          1120          6850
                                                                   15           380          1220          7690
----------------------------------------------------------------------------------------------------------------
\*\The tow depth has minimal effect on the maximum near-field output and the shape of the frequency spectrum for
  the single 40 in\3\ airgun; thus the predicted safety radii are essentially the same at each tow depth.

    The L-DEO model applied to airgun configuration does not allow for 
bottom interactions, and thus is most directly applicable to deep water 
and to relatively short ranges. The calculated distances are expected 
to overestimate the actual distances to the corresponding Sound 
Pressure Levels (SPL), given the deep-water results of Tolstoy et al. 
(2004a,b). Additional information regarding how the safety radii were 
calculated and how the empirical measurements were used to correct the 
modeled numbers may be found in Appendix A of L-DEO=s Environmental 
Assessment (EA). The conclusion that the model predictions in Table 1 
are precautionary, relative to actual 180- and 190-dB (rms) radii, is 
based on empirical data from the acoustic calibration of different 
airgun configurations used by the R/V Maurice Ewing (Ewing) in the 
northern Gulf of Mexico. (Tolstoy et al., 2004a,b).
    L-DEO conducted a more extensive acoustic calibration study of the 
Langseth=s 36-airgun array in late 2007/early 2008 in the northern Gulf 
of Mexico (LGL Ltd., 2006; Holst and Beland, 2008). L-DEO is currently 
modeling the distances to the corresponding Sound Pressure Levels (SPL) 
(e.g., 190, 180, and 160 dB re 1 microPa (rms)) for various airgun 
configurations and water depths. Those results are not yet available. 
However, the empirical data from the 2007/2008 calibration study will 
be used to refine the exclusion zones proposed above for use during 
survey, if the data are appropriate and available at the time of the 
survey.

Description of Marine Mammals in the Activity Area

    Thirty-three marine mammal species may occur off the coast of 
British Columbia, Canada, including 20 odontocetes (toothed cetaceans), 
7 mysticetes (baleen whales), 5 pinnipeds, and the sea otter (Enhydra 
sp.). In the United States, sea otters are managed by the U.S. Fish and 
Wildlife Service (USFWS) and are unlikely to be encountered in or near 
the Endeavor Marine Protected Area where seismic operations will occur, 
and are, therefore, not addressed further in this document. Eight of 
these species are listed as endangered under the U.S. Endangered 
Species Act of 1973 (ESA), including the Steller sea lion (Eumetopias 
jubatus), the humpback (Megaptera

[[Page 21634]]

novaeanliae), sei (Balaenoptera borealis), fin (Balenoptera physalus), 
blue (Balenoptera musculus), North Pacific right (Eubalena japonica), 
sperm (Physeter macrocephalus), and Southern Resident killer (Orcinus 
orca) whales.
    This proposed IHA will only address requested take authorizations 
for cetaceans and pinnipeds. Table 2 below outlines the species, their 
habitat and abundance in the proposed survey area, the estimated number 
of exposures (based on average density) to sound levels greater than or 
equal to 160 dB during the seismic survey if no animals moved away from 
the survey vessel.

--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                      Estimated Number
                                                                                                    Estimated Number   of Individuals    Approx. Percent
            Species                      Habitat          Abundance in the NE   Occurrence in the    of Exposures to  Exposed to Sound     of Regional
                                                                Pacific            Survey Area        Sound Levels         Levels          Population
                                                                                                     [gteqt] 160 dB     [gteqt]160 dB
--------------------------------------------------------------------------------------------------------------------------------------------------------
North Pacific right whale*      Coastal and shelf waters  100-200              Rare and unlikely    0                 0                 0
--------------------------------------------------------------------------------------------------------------------------------------------------------
Humpback whale*                 Coastal waters            >6000                Uncommon             29                6                 0.10
--------------------------------------------------------------------------------------------------------------------------------------------------------
Minke whale                     Coastal and shelf waters  9000                 Uncommon             26                26                0.06
--------------------------------------------------------------------------------------------------------------------------------------------------------
Sei whale                       Pelagic                   7260 - 12,620        Uncommon             5                 1                 0.01
--------------------------------------------------------------------------------------------------------------------------------------------------------
Fin whale*                      Pelagic, shelf and        13,620-18,680        Uncommon             39                8                 0.05
                                 coastal waters
--------------------------------------------------------------------------------------------------------------------------------------------------------
Blue whale*                     Pelagic, shelf and        1186                 Uncommon             8                 2                 0.14
                                 inshore waters
--------------------------------------------------------------------------------------------------------------------------------------------------------
Sperm whale*                    Pelagic                   24,000               Uncommon             52                10                0.04
--------------------------------------------------------------------------------------------------------------------------------------------------------
Pygmy sperm whale               Deep waters off the       Not available        Common               47                9                 Not available
                                 shelf
--------------------------------------------------------------------------------------------------------------------------------------------------------
Dwarf Sperm whale               Deep waters off the       Not available        Uncommon             0                 0                 0.0
                                 shelf
--------------------------------------------------------------------------------------------------------------------------------------------------------
Baird's beaked whale            Deep waters and cont.     6000                 Common               62                13                0.21
                                 slopes
--------------------------------------------------------------------------------------------------------------------------------------------------------
Blainville's beaked whale       Deep waters and cont.     603                  Uncommon             8                 2                 0.28
                                 slopes
--------------------------------------------------------------------------------------------------------------------------------------------------------
Cuvier's beaked whale           Pelagic                   20,000               Uncommon             0                 0                 0.0
--------------------------------------------------------------------------------------------------------------------------------------------------------
Hubb's beaked whale             Deep waters and cont.     421                  Uncommon             8                 2                 0.40
                                 slopes
--------------------------------------------------------------------------------------------------------------------------------------------------------
Stejneger's beaked whale        Deep waters               421                  Uncommon             8                 2                 0.40
--------------------------------------------------------------------------------------------------------------------------------------------------------
Bottlenose dolphin              Coastal and offshore      3257                 Rare                 0                 0                 0.0
                                 waters
--------------------------------------------------------------------------------------------------------------------------------------------------------
Striped dolphin                 Pelagic                   23,883               rare                 2                 0                 0.0
--------------------------------------------------------------------------------------------------------------------------------------------------------
Short-beaked common dolphin     Coastal and offshore      487,622              Common               511               104               0.02
                                 waters
--------------------------------------------------------------------------------------------------------------------------------------------------------
Pacific white-sided dolphin     Pelagic, shelf and slope  931,000              Common               895               181               0.02
                                 waters
--------------------------------------------------------------------------------------------------------------------------------------------------------
Northern right-whale dolphin    Pelagic, shelf and slope  15,305               Common               699               142               0.93
                                 waters
--------------------------------------------------------------------------------------------------------------------------------------------------------
Risso's dolphin                 Pelagic                   12,093               Common               467               95                0.78
--------------------------------------------------------------------------------------------------------------------------------------------------------
False killer whale              Pelagic                   Not available        Rare                 0                 0                 0.0
--------------------------------------------------------------------------------------------------------------------------------------------------------
Killer whale                    Widely distributed        8500                 Uncommon             61                12                0.15
--------------------------------------------------------------------------------------------------------------------------------------------------------
Short-finned pilot whale        Pelagic                   160,200              Uncommon             0                 0                 00.0
--------------------------------------------------------------------------------------------------------------------------------------------------------

[[Page 21635]]

 
Dall's porpoise                 Offshore and nearshore    57,549               Common               5337              1081              1.88
                                 waters
--------------------------------------------------------------------------------------------------------------------------------------------------------
Northern fur seal               Coastal                   721,935              Common               360               73                0.01
--------------------------------------------------------------------------------------------------------------------------------------------------------
Total                           ........................  ...................  ...................  8,624             1,748             ................
--------------------------------------------------------------------------------------------------------------------------------------------------------
--------------------------------------------------------------------------------------------------------------------------------------------------------
Table 2. Abundance, preferred habitat, and commonness of the marine mammal species that may be encountered during the proposed survey within the ETOMO
  survey area. The far right columns indicate the estimated number of each species that will be exposed to [gteqt]160 dB based on average density
  estimates. NMFS believes that, when mitigation measures are taken into consideration, the activity is likely to result in take of numbers of animals
  less than those indicated by the column titled NUmber of Individuals Exposed [gteqt]160 dB.
* Federally listed endangered species.

    Detailed information regarding the status and distribution of these 
marine mammals may be found in sections III and IV of L-DEO's 
application.

Potential Effects of the Proposed Activity on Marine Mammals

Summary of Potential Effects of Airgun Sounds on Marine Mammals

    The effects of sounds from airguns might include one or more of the 
following: tolerance, masking of natural sounds, behavioral 
disturbance, temporary or permanent hearing impairment, or non-auditory 
physical or physiological effects (Richardson et al., 1995; Gordon et 
al., 2004; Nowacek et al., 2007; Southall et al., 2007). Permanent 
hearing impairment, in the unlikely event that it occurred, would 
constitute injury, but temporary threshold shift (TTS) is not an injury 
(Southall et al., 2007). Although the possibility cannot be entirely 
excluded, it is unlikely that the project would result in any cases of 
temporary or permanent hearing impairment, or any significant non-
auditory physical or physiological effects. Some behavioral disturbance 
is expected, but is expected to be localized and short-term.

Tolerance

    Numerous studies have shown that pulsed sounds from airguns are 
often readily detectable in the water at distances of many kilometers. 
For a brief summary of the characteristics of airgun pulses, see 
Appendix B of L-DEO's application. Several studies have also shown that 
marine mammals at distances more than a few kilometers from operating 
seismic vessels often show no apparent response (tolerance) (see 
Appendix B (5) of L-DEO's EA). That is often true even in cases when 
the pulsed sounds must be readily audible to the animals based on 
measured received levels and the hearing sensitivity of 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 usually seem to be 
more tolerant of exposure to airgun pulses than cetaceans, with the 
relative responsiveness of baleen and toothed whales being variable.

Masking

    Introduced underwater sound may, through masking, reduce the 
effective communication distance of a marine mammal species if the 
frequency of the source is close to that used as a signal by the marine 
mammal, and if the anthropogenic sound is present for a significant 
fraction of the time (Richardson et al., 1995).
    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. 
Because of the intermittent nature and low duty cycle of seismic 
pulses, animals can emit and receive sounds in the relatively quiet 
intervals between pulses. However, in some situations, multi-path 
arrivals and reverberation cause airgun sound to arrive for much or all 
of the interval between pulses (e.g., Simard et al., 2005; Clark and 
Gagnon, 2006) which could mask calls. Some baleen and toothed whales 
are known to continue calling in the presence of seismic pulses, and 
their calls can usually 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; Holst et al., 2005a,b, 
2006). In the northeast Pacific Ocean, blue whale calls have been 
recorded during a seismic survey off Oregon (McDonald et al., 1995). 
Among odontocetes, there has been one report that sperm whales ceased 
calling when exposed to pulses from a very distant seismic ship (Bowles 
et al., 1994). However, more recent studies found that this species 
continued calling in the presence of seismic pulses (Madsen et al., 
2002; Tyack et al., 2003; Smultea et al., 2004; Holst et al., 2006; 
Jochens et al., 2006, 2008). Dolphins and porpoises commonly are heard 
calling while airguns are operating (e.g., Gordon et al., 2004; Smultea 
et al., 2004; Holst et al., 2005a,b; Potter et al., 2007). The sounds 
important to small odontocetes are predominantly at much higher 
frequencies than are the dominant components of airgun sounds, thus 
limiting the potential for masking. In general, masking effects of 
seismic pulses are expected to be negligible, given the normally 
intermittent nature of seismic pulses. Masking effects on marine 
mammals are discussed further in Appendix B (4) of L-DEO's EA.

Disturbance Reactions

    Disturbance includes a variety of effects, including subtle to 
conspicuous changes in behavior, movement, and displacement. Based on 
NMFS (2001, p. 9293), NRC (2005), and Southall et al. (2007), L-DEO 
assumes that simple exposure to sound, or brief reactions that do not 
disrupt behavioral patterns in a potentially significant manner, do not 
constitute harassment or ``taking''. By potentially significant, L-DEO 
means ``in a manner that might have deleterious effects to the well-
being of individual marine mammals or their populations''.
    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 does react briefly to an

[[Page 21636]]

underwater sound by changing its behavior or moving a small distance, 
the impacts of the change are unlikely to be significant to the 
individual, let alone the stock or population. However, if a sound 
source displaces marine mammals from an important feeding or breeding 
area for a prolonged period, impacts on individuals and populations 
could be significant (e.g., Lusseau and Bejder, 2007; Weilgart, 2007). 
Given the many uncertainties in predicting the quantity and types of 
impacts of noise on marine mammals, it is common practice to estimate 
how many mammals would be present within a particular distance of 
industrial activities and exposed to a particular level of industrial 
sound. In most cases, this approach likely overestimates the numbers of 
marine mammals that would be 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 primarily on behavioral observations of a few species. 
Detailed studies have been done on humpback, gray (Eshrichtius 
robustus), bowhead (Balena mysticetes), and sperm whales, and on ringed 
seals (Pusa hispida). Less detailed data are available for some other 
species of baleen whales, and small toothed whales, but for many 
species there are no data on responses to marine seismic surveys.
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 B (5) of L-DEO's EA, baleen whales exposed to 
strong noise pulses from airguns often react by deviating from their 
normal migration route and/or interrupting their feeding and moving 
away. In the cases of migrating gray and bowhead whales, the observed 
changes in behavior appeared to be of little or no biological 
consequence to the animals. They simply avoided the sound source by 
displacing their migration route to varying degrees, but within the 
natural boundaries of the migration corridors.
    Studies of gray, bowhead, and humpback whales have shown that 
seismic pulses with received levels of 160 170 dB re 1 microPa (rms) 
seem to cause obvious avoidance behavior in a substantial fraction of 
the animals exposed (Richardson et al., 1995). In many areas, seismic 
pulses from large arrays of airguns diminish to those levels at 
distances ranging from 4-15 km (2.5-9.3 mi) from the source. A 
substantial proportion of the baleen whales within those distances may 
show avoidance or other strong behavioral reactions to the airgun 
array. Subtle behavioral changes sometimes become evident at somewhat 
lower received levels, and studies summarized in Appendix B of L-DEO's 
EA have shown that some species of baleen whales, notably bowhead and 
humpback whales, at times show strong avoidance at received levels 
lower than 160 170 dB re 1 microPa (rms).
    Responses of humpback whales to seismic surveys have been studied 
during migration, on summer feeding grounds, and on Angolan winter 
breeding grounds; there has also been discussion of effects on the 
Brazilian wintering grounds. McCauley et al. (1998, 2000a) studied the 
responses of humpback whales off Western Australia to a full-scale 
seismic survey with a 16-airgun, 2678-in\3\ array, and to a single 20-
in\3\ airgun with source level of 227 dB re 1 microPa m (peak to peak). 
McCauley et al. (1998) documented that avoidance reactions began at 5-8 
km (3-5 mi) from the array, and that those reactions kept most pods 
approximately 3-4 km (1.8-2.5 mi) from the operating seismic boat. 
McCauley et al. (2000a) noted localized displacement during migration 
of 4-5 km (2.5-3.1 mi) by traveling pods and 7-12 km (4.3-7.5 mi) by 
more sensitive resting pods of 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 the received sound levels. The 
mean received level for initial avoidance of an approaching airgun was 
140 dB re 1 microPa (rms) for humpback pods containing females, and at 
the mean closest point of approach distance the received level was 143 
dB re 1 microPa (rms). The initial avoidance response generally 
occurred at distances of 5-8 km (3.1-4.9 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 
(328-1312 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). Malme et al. 
reported that some of the humpbacks seemed startled at received levels 
of 150 169 dB re 1 microPa and concluded that there was no clear 
evidence of avoidance, despite the possibility of subtle effects, at 
received levels up to 172 re 1 FPa on an approximate rms basis.
    It has been suggested that South Atlantic humpback whales wintering 
off Brazil may be displaced or even strand upon exposure to seismic 
surveys (Engel et al., 2004). The evidence for this was circumstantial 
and subject to alternative explanations (IAGC, 2004). Also, the 
evidence was not consistent with subsequent results from the same area 
of Brazil (Parente et al., 2006), or with 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).
    There are no data on reactions of right whales to seismic surveys, 
but results from the closely-related bowhead whale show that their 
responsiveness can be quite variable depending on their activity 
(migrating vs. feeding). Bowhead whales migrating west across the 
Alaskan Beaufort Sea in autumn, in particular, are unusually 
responsive, with substantial avoidance occurring out to distances of 20 
- 30 km (12.4 - 18.6 mi) from a medium-sized airgun source at received 
sound levels of around 120 130 dB re 1 microPa (rms) (Miller et al., 
1999; Richardson et al., 1999; see Appendix B (5) of the EA. However, 
more recent research on bowhead whales (Miller et al., 2005; Harris et 
al., 2007) corroborates earlier evidence that, during the summer 
feeding season, bowheads are not as sensitive to seismic sources. 
Nonetheless, subtle but statistically significant changes in surfacing 
respiration dive cycles were evident upon statistical analysis 
(Richardson et al., 1986). In summer, bowheads typically begin to show 
avoidance reactions at received levels of about 152 178 dB re 1 microPa 
(rms) (Richardson et al., 1986, 1995; Ljungblad et al., 1988; Miller et 
al., 2005).
    Reactions of migrating and feeding (but not wintering) gray whales 
to seismic surveys have been studied. Malme et al. (1986, 1988) studied 
the responses of feeding eastern Pacific gray whales to pulses from a 
single 100-in\3\ airgun off St. Lawrence Island in the northern Bering 
Sea. They estimated, based on small sample sizes, that 50 percent of 
feeding gray whales stopped 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 re

[[Page 21637]]

1 microPa (rms). Those findings were generally consistent with the 
results of experiments conducted on larger numbers of gray whales that 
were migrating along the California coast (Malme et al., 1984; Malme 
and Miles, 1985), and western Pacific gray whales feeding off Sakhalin 
Island, Russia (Wursig et al., 1999; Gailey et al., 2007; Johnson et 
al., 2007; Yazvenko et al., 2007a,b), along with data on gray whales 
off British Columbia (Bain and Williams, 2006).
    Various species of Balaenoptera (blue, sei, fin, and minke whales) 
have occasionally been reported in areas ensonified by airgun pulses 
(Stone, 2003; MacLean and Haley, 2004; Stone and Tasker, 2006). 
Sightings by observers on seismic vessels off the United Kingdom from 
1997 to 2000 suggest that, during times of good sightability, sighting 
rates for mysticetes (mainly fin and sei whales) were similar when 
large arrays of airguns were shooting vs. silent (Stone, 2003; Stone 
and Tasker, 2006). However, these whales tended to exhibit localized 
avoidance, remaining significantly further (on average) from the airgun 
array during seismic operations compared with non-seismic periods 
(Stone and Tasker, 2006). In a study off Nova Scotia, Moulton and 
Miller (2005) found little difference in sighting rates (after 
accounting for water depth) and initial sighting distances of 
balaenopterid whales when airguns were operating versus silent. 
However, there were indications that these whales were more likely to 
be moving away when seen during airgun operations. Similarly, ship-
based monitoring studies of blue, fin, sei and minke whales offshore of 
Newfoundland (Orphan Basin and Laurentian Sub-basin) found no more than 
small differences in sighting rates and swim directions during seismic 
vs. non-seismic periods Moulton et al., 2005, 2006a,b).
    Data on short-term reactions by cetaceans to impulsive noises are 
not necessarily indicative of long-term or biologically significant 
effects. It is not known whether impulsive sounds affect reproductive 
rate or distribution and habitat use in subsequent days or years. 
However, gray whales have continued to migrate annually along the west 
coast of North America with substantial increases in the population 
over recent years, despite intermittent seismic exploration (and much 
ship traffic) in that area for decades (Appendix A in Malme et al., 
1984; Richardson et al., 1995; Angliss and Outlaw, 2008). The western 
Pacific gray whale population did not seem affected by a seismic survey 
in its feeding ground during a previous year (Johnson et al., 2007). 
Similarly, bowhead whales have continued to travel to the eastern 
Beaufort Sea each summer, and their numbers have increased notably, 
despite seismic exploration in their summer and autumn range for many 
years (Richardson et al., 1987; Angliss and Outlaw, 2008).
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 and (in more 
detail) in Appendix B of L-DEO's EA have been reported for toothed 
whales. However, there are recent systematic studies on sperm whales 
(Jochens et al., 2006; Miller et al., 2006), and there is an increasing 
amount of information about responses of various odontocetes to seismic 
surveys based on monitoring studies (e.g., Stone, 2003; Smultea et al., 
2004; Moulton and Miller, 2005; Bain and Williams, 2006; Holst et al., 
2006; Stone and Tasker, 2006; Potter et al., 2007; Weir, 2008).
    Seismic operators and marine mammal observers on seismic vessels 
regularly see dolphins and other small toothed whales near operating 
airgun arrays, but in general there is a tendency for most delphinids 
to show some avoidance of operating seismic vessels (e.g., Goold, 
1996a,b,c; Calambokidis and Osmek, 1998; Stone, 2003; Moulton and 
Miller, 2005; Holst et al., 2006; Stone and Tasker, 2006; Weir, 2008). 
Some dolphins seem to be attracted to the seismic vessel and floats, 
and some ride the bow wave of the seismic vessel even when large arrays 
of airguns are firing (e.g., Moulton and Miller, 2005). Nonetheless, 
small toothed whales more often 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 (e.g., Stone and Tasker, 
2006; Weir, 2008). In most cases the avoidance radii for delphinids 
appear to be small, on the order of 1 km less, and some individuals 
show no apparent avoidance. The beluga (Delphinapterus leucas) is a 
species that (at times) shows long-distance avoidance of seismic 
vessels. Aerial surveys conducted in the southeastern Beaufort Sea 
during summer found that sighting rates of beluga whales were 
significantly lower at distances 10-20 km (6.2-12.4 mi) compared with 
20-30 km (12.4-18.6 mi) from an operating airgun array, and observers 
on seismic boats in that area rarely see belugas (Miller et al., 2005; 
Harris et al., 2007).
    Captive bottlenose dolphins (Tursiops truncates) and beluga whales 
exhibited changes in behavior when exposed to strong pulsed sounds 
similar in duration to those typically used in seismic surveys 
(Finneran et al., 2000, 2002, 2005). However, the animals tolerated 
high received levels of sound before exhibiting aversive behaviors.
    Results for porpoises depend on species. The limited available data 
suggest that harbor porpoises (Phocoena phocoena) show stronger 
avoidance of seismic operations than do Dall's porpoises (Phocoenoides 
dalli) (Stone, 2003; MacLean and Koski, 2005; Bain and Williams, 2006; 
Stone and Tasker, 2006). Dall's porpoises seem relatively tolerant of 
airgun operations (MacLean and Koski, 2005; Bain and Williams, 2006), 
although they too have been observed to avoid large arrays of operating 
airguns (Calambokidis and Osmek, 1998; Bain and Williams, 2006). This 
apparent difference in responsiveness of these two porpoise species is 
consistent with their relative responsiveness to boat traffic and some 
other acoustic sources (Richardson et al., 1995; Southall et al., 
2007).
    Most studies of sperm whales exposed to airgun sounds indicate that 
the sperm whale shows considerable tolerance of airgun pulses (e.g., 
Stone, 2003; Moulton et al., 2005, 2006a; Stone and Tasker, 2006; Weir, 
2008). In most cases the whales do not show strong avoidance, and they 
continue to call (see Appendix B of L-DEO's EA for review). However, 
controlled exposure experiments in the Gulf of Mexico indicate that 
foraging behavior was altered upon exposure to airgun sound (Jochens et 
al., 2006). In the Sperm Whale Seismic Study (SWSS), D-tags (Johnson 
and Tyack, 2003) were used to record the movement and acoustic exposure 
of eight foraging sperm whales before, during, and after controlled 
sound exposures of airgun arrays in the Gulf of Mexico (Jochens et al., 
2008). Whales were exposed to maximum received sound levels between 111 
and 147 dB re 1 microPa rms (131 - 164 dB re 1 microPa pk-pk) at ranges 
of approximately 1.4 - 12.6 km (0.8 - 7.8 mi) from the sound source. 
Although the tagged whales showed no horizontal avoidance, some whales 
changed foraging behavior during full-array exposure (Jochens et al., 
2008).
    There are almost no specific data on the behavioral reactions of 
beaked whales to seismic surveys. However, northern bottlenose whales 
continued to produce high-frequency clicks when exposed to sound pulses 
from distant

[[Page 21638]]

seismic surveys (Laurinolli and Cochrane, 2005; Simard et al., 2005). 
Most beaked whales tend to avoid approaching vessels of other types 
(e.g., Wursig et al., 1998). They may also dive for an extended period 
when approached by a vessel (e.g., Kasuya, 1986), although it is 
uncertain how much longer such dives may be as compared to dives by 
undisturbed beaked whales, which also are often quite long (Baird et 
al., 2006; Tyack et al., 2006). In any event, it is likely that most 
beaked whales would also show strong avoidance of an approaching 
seismic vessel, although this has not been documented explicitly.
    There are increasing indications that some beaked whales tend to 
strand when naval exercises involving mid-frequency sonar operation are 
ongoing nearby (e.g., Simmonds and Lopez-Jurado, 1991; Frantzis, 1998; 
NOAA and USN, 2001; Jepson et al., 2003; Hildebrand, 2005; Barlow and 
Gisiner, 2006; see also the ``Strandings and Mortality'' subsection, 
later). These strandings are apparently at least in part a disturbance 
response, although auditory or other injuries or other physiological 
effects may also be involved. Whether beaked whales would ever react 
similarly to seismic surveys is unknown (see ``Strandings and 
Mortality'', below). Seismic survey sounds are quite different from 
those of the sonars in operation during the above-cited incidents, and 
in particular, the dominant frequencies in airgun pulses are at lower 
frequencies than used by mid-frequency naval sonars.
    Odontocete reactions to large arrays of airguns are variable and, 
at least for delphinids and some porpoises (e.g., Dall's, Phocoenoides 
dalli), seem to be confined to a smaller radius than has been observed 
for the more responsive of the mysticetes, belugas, and harbor 
porpoises (refer to Appendix B in L-DEO's EA).
Pinnipeds
    Pinnipeds are not likely to show a strong avoidance reaction to the 
airgun array. Visual monitoring from seismic vessels has shown only 
slight (if any) avoidance of airguns by pinnipeds, and only slight (if 
any) changes in behavior see Appendix B (5) of the EA. In the Beaufort 
Sea, some ringed seals avoided an area of 100 m (328 ft) to (at most) a 
few hundred meters around seismic vessels, but many seals remained 
within 100 - 200 m (328 656 ft) of the trackline as the operating 
airgun array passed by (e.g., Harris et al., 2001; Moulton and Lawson 
2002; Miller et al., 2005). Ringed seal sightings averaged somewhat 
farther away from the seismic vessel when the airguns were operating 
than when they were not, but the difference was small (Moulton and 
Lawson, 2002). Similarly, in Puget Sound, sighting distances for harbor 
seals (Phoca vitulina) and California sea lions (Zalophus 
californianus) tended to be larger when airguns were operating 
(Calambokidis and Osmek, 1998). Previous telemetry work suggests that 
avoidance and other behavioral reactions may be stronger than evident 
to date from visual studies (Thompson et al., 1998). 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-term effects on pinniped individuals or populations.

Hearing Impairment and Other Physical Effects

    Temporary or permanent hearing impairment is a possibility when 
marine mammals are exposed to very strong sounds, and temporary 
threshold shift (TTS) has been demonstrated and studied in certain 
captive odontocetes and pinnipeds exposed to strong sounds (reviewed in 
Southall et al., 2007).
    Current NMFS policy regarding exposure of marine mammals to high-
level sounds is that cetaceans and pinnipeds should not be exposed to 
impulsive sounds with received levels greater than or equal to 180 and 
190 dB re 1 microPa rms, respectively (NMFS 2000). L-DEO has used those 
criteria to establish the exclusion (i.e., shut-down) zones planned for 
the proposed seismic survey. However, those criteria were established 
before there was any information about minimum received levels of 
sounds necessary to cause auditory impairment in marine mammals. As 
discussed in Appendix B of the EA: (1) the 180-dB criterion for 
cetaceans is probably quite precautionary, i.e., lower than necessary 
to avoid temporary auditory impairment let alone permanent auditory 
injury; (2) NMFS treats TTS as the upper bound of Level B Harassment. 
Tissues are not irreparably damaged with the onset of TTS, the effects 
are temporary (particularly for onset-TTS), and NMFS does not believe 
that this effect qualifies as an injury; (3) the minimum sound level 
necessary to cause permanent hearing impairment (``Level A 
harassment'') is higher, by a variable and generally unknown amount, 
than the level that induces barely detectable TTS; and (4) the level 
associated with the onset of TTS is often considered to be a level 
below which there is no danger of permanent damage. The actual PTS 
threshold is likely to be well above the level causing onset of TTS 
(Southall et al., 2007).
    Recommendations for new science-based noise exposure criteria for 
marine mammals, frequency-weighting procedures, and related matters 
were published recently (Southall et al., 2007). Those recommendations 
have not, as of early 2009, been formally adopted by NMFS for use in 
regulatory processes and during mitigation programs associated with 
seismic surveys. However, some aspects of the recommendations have been 
taken into account in certain Environmental Impact Statements and 
small-take authorizations. NMFS has indicated that it may issue new 
noise exposure criteria for marine mammals that account for the now 
available scientific data on TTS, the expected offset between the TTS 
and PTS thresholds, differences in the acoustic frequencies to which 
different marine mammal groups are sensitive, and other relevant 
factors. Preliminary information about possible changes in the 
regulatory and mitigation requirements, and about the possible 
structure of new criteria, was given by Wieting (2004) and NMFS (2005).
    Several aspects of the planned monitoring and mitigation measures 
for this project are designed to detect marine mammals occurring near 
the airgun array, and to avoid exposing them to sound pulses that 
might, at least in theory, cause hearing impairment (see section XI of 
L-DEO's application). In addition, many cetaceans and (to a limited 
degree) pinnipeds and sea turtles show some avoidance of the area where 
received levels of airgun sound are high enough such that hearing 
impairment could potentially occur. In those cases, the avoidance 
responses of the animals themselves will reduce or (most likely) avoid 
any possibility of hearing impairment.
    Non-auditory physical effects might also occur in marine mammals 
exposed to strong underwater pulsed sound. Possible types of non-
auditory physiological effects or injuries that might (in theory) occur 
in mammals close to a strong sound source include stress, neurological 
effects, bubble formation, 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 unlikely 
that any effects of these types would occur during the proposed

[[Page 21639]]

project given the brief duration of exposure of any given mammal, the 
deep water in the survey area, 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. In terrestrial mammals, 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 in both terrestrial and marine 
mammals 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. Available data on TTS 
in marine mammals are summarized in Southall et al. (2007).
    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 energy level of a single seismic pulse 
(with no frequency weighting) might need to be approximately 186 dB re 
1 microPa\2\<bullet>s (i.e., 186 dB SEL or approximately 196 201 dB re 
1 microPa rms in order to produce brief, mild TTS. Exposure to several 
strong seismic pulses that each have received levels near 190 dB re 1 
microPa rms might result in cumulative exposure of approximately 186 dB 
SEL and thus 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 Langseth's airguns at 
which the received energy level (per pulse, flat-weighted) would be 
expected to be greater than or equal to 190 dB re 1 microPa rms are 
estimated in Table 1. Levels greater than or equal to 190 dB re 1 
microPa rms are expected to be restricted to radii no more than 380 m 
(1246 ft) (See Table 1). For an odontocete closer to the surface, the 
maximum radius with greater than or equal to 190 dB re 1 microPa rms 
would be smaller.
    The above TTS information for odontocetes is derived from studies 
on the bottlenose dolphin and beluga. There is no published TTS 
information for other types of cetaceans. However, preliminary evidence 
from a harbor porpoise exposed to airgun sound suggests that its TTS 
threshold may have been lower (Lucke et al., 2007).
    For baleen whales, there are no data, direct or indirect, on levels 
or properties of sound that are required to induce TTS. The frequencies 
to which baleen whales are most sensitive are assumed to be 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 (Southall et al., 2007). In any event, 
no cases of TTS are expected given three considerations: (1) the low 
abundance of baleen whales in most parts of the planned study area; (2) 
the strong likelihood that baleen whales would avoid the approaching 
airguns (or vessel) before being exposed to levels high enough for TTS 
to occur; and (3) the mitigation measures that are planned.
    In pinnipeds, TTS thresholds associated with exposure to brief 
pulses (single or multiple) of underwater sound have not been measured. 
Initial evidence from more prolonged (non-pulse) exposures suggested 
that some pinnipeds (harbor seals in particular) incur TTS at somewhat 
lower received levels than do small odontocetes exposed for similar 
durations (Kastak et al., 1999, 2005; Ketten et al., 2001). The TTS 
threshold for pulsed sounds has been indirectly estimated as being an 
SEL of approximately 171 dB re 1 microPa\2\<bullet>s (Southall et al., 
2007), which would be equivalent to a single pulse with received level 
of approximately 181 - 186 dB re 1 microPa (rms), or a series of pulses 
for which the highest rms values are a few dB lower. Corresponding 
values for California sea lions and northern elephant seals (Mirounga 
angustirostris) are likely to be higher (Kastak et al., 2005).
    NMFS (1995, 2000) concluded that cetaceans and pinnipeds should not 
be exposed to pulsed underwater noise at received levels exceeding 180 
and 190 dB re 1 microPa rms, respectively. Those sound levels are 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 and in Southall et al. (2007), data 
that are now available imply that TTS is unlikely to occur in most 
odontocetes (and probably mysticetes as well) unless they are exposed 
to a sequence of several airgun pulses in which the strongest pulse has 
a received level substantially exceeding 180 dB re 1 microPa rms. On 
the other hand, for the harbor seal and any species with similarly low 
TTS thresholds (possibly including the harbor porpoise), TTS may occur 
upon exposure to one or more airgun pulses whose received level equals 
the NMFS ``do not exceed'' value of 190 dB re 1 microPa rms. That 
criterion corresponds to a single-pulse SEL of
    175 - 180 dB re 1 microPa\2\<bullet>s in typical conditions, 
whereas TTS is suspected to be possible (in harbor seals) with a 
cumulative SEL of approximately 171 dB re 1 microPa\2\<bullet>s.
Permanent Threshold Shift (PTS)
    When PTS occurs, there is physical damage to the sound receptors in 
the ear. In severe 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 (Kryter, 1985).
    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 at least mild TTS, there has been further speculation 
about the possibility that some individuals occurring very close to 
airguns might incur PTS (Richardson et al., 1995, p. 372ff). Single or 
occasional occurrences of mild TTS are not indicative of permanent 
auditory damage.
    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 B (6) 
of L-DEO's EA. 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 greater than 6 
dB (Southall et al., 2007). On an SEL basis, Southall et al. (2007:441-
4) estimated that received levels would need to exceed the TTS 
threshold by at least 15 dB for

[[Page 21640]]

there to be risk of PTS. Thus, for cetaceans they estimate that the PTS 
threshold might be a mammal-weighted (M-weighted) SEL (for the sequence 
of received pulses) of approximately 198 dB re 1 microPa\2\<bullet>s 
(15 dB higher than the TTS threshold for an impulse), where the SEL 
value is accumulated over the sequence of pulses. Additional 
assumptions had to be made to derive a corresponding estimate for 
pinnipeds, as the only available data on TTS-thresholds in pinnipeds 
pertain to non-impulse sound. Southall et al. (2007) estimate that the 
PTS threshold could be a cumulative Mpw-weighted SEL of approximately 
186 dB re 1 microPa\2\<bullet>s in the harbor seal exposed to impulse 
sound. The PTS threshold for the California sea lion and northern 
elephant seal the PTS threshold would probably be higher, given the 
higher TTS thresholds in those species.
    Southall et al. (2007) also note 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 
re 1 microPa (peak), respectively. A peak pressure of 230 dB re 1 FPa 
(3.2 bar<bullet>m, 0-peak) would only be found within a few meters of 
the largest (360 in\3\) airgun in the planned airgun array (Caldwell 
and Dragoset, 2000). A peak pressure of 218 dB re 1 microPa could be 
received somewhat farther away; to estimate that specific distance, one 
would need to apply a model that accurately calculates peak pressures 
in the nearfield around an array of airguns.
    Given the higher level of sound necessary to cause PTS as compared 
with TTS, it is considerably less likely that PTS would occur. 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, PAM, 
power downs, and shut downs of the airguns when mammals are seen within 
or approaching the exclusion zones, will further reduce the 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, and 
other types of organ or tissue damage (Cox et al., 2006; Southall et 
al., 2007). Studies examining such effects are limited. However, 
resonance (Gentry, 2002) and direct noise-induced bubble formation 
(Crum et al., 2005) are not expected in the case of an impulsive source 
like an airgun array. If seismic surveys disrupt diving patterns of 
deep-diving species, this might perhaps result in bubble formation and 
a form of the bends, as speculated to occur in beaked whales exposed to 
sonar. However, there is no specific evidence of this upon exposure to 
airgun pulses.
    In general, very little is known about the potential for seismic 
survey sounds (or other types of strong underwater sounds) to cause 
non-auditory physical effects in marine mammals. Such effects, if they 
occur at all, would presumably be limited to short distances and to 
activities that extend over a prolonged period. The available data do 
not allow identification of a specific exposure level above which non-
auditory effects can be expected (Southall et al., 2007), or any 
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 
non-auditory physical effects. Also, the planned mitigation measures 
(see section XI), including shut downs of the airguns, will reduce any 
such effects that might otherwise occur.

Strandings and Mortality

    Marine mammals close to underwater detonations of high explosives 
can be killed or severely injured, and the auditory organs are 
especially susceptible to injury (Ketten et al., 1993; Ketten, 1995). 
However, explosives are no longer used for marine seismic research or 
commercial seismic surveys, and have been replaced entirely by airguns 
or related non-explosive pulse generators. Airgun pulses are less 
energetic and have slower rise times, and there is no specific evidence 
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 (Malakoff, 2002; Cox et al., 2006), 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 (e.g., Hildebrand, 2005; Southall et al., 2007). 
Appendix B (7) of L-DEO's EA provides additional details.
    Specific sound-related processes that lead to strandings and 
mortality are not well documented, but may include: (1) swimming in 
avoidance of a sound into shallow water; (2) a change in behavior (such 
as a change in diving behavior) that might contribute to tissue damage, 
gas bubble formation, hypoxia, cardiac arrhythmia, hypertensive 
hemorrhage or other forms of trauma; (3) a physiological change such as 
a vestibular response leading to a behavioral change or stress-induced 
hemorrhagic diathesis, leading in turn to tissue damage; and (4) tissue 
damage directly from sound exposure, such as through acoustically 
mediated bubble formation and growth or acoustic resonance of tissues. 
There are increasing indications that gas-bubble disease (analogous to 
``the bends''), induced in supersaturated tissue by a behavioral 
response to acoustic exposure, could be a pathologic mechanism for the 
strandings and mortality of some deep-diving cetaceans exposed to 
sonar. However, the evidence for this remains circumstantial and 
associated with exposure to naval mid-frequency sonar, not seismic 
surveys (Cox et al., 2006; Southall et al., 2007).
    Seismic pulses and mid-frequency sonar signals are quite different, 
and some mechanisms by which sonar sounds have been hypothesized to 
affect beaked whales are unlikely to apply to airgun pulses. Sounds 
produced by airgun arrays are broadband impulses with most of the 
energy below 1 kHz. Typical military mid-frequency sonars emit non-
impulse sounds at frequencies of 2-10 kHz, generally with a relatively 
narrow bandwidth at any one time. A further difference between seismic 
surveys and naval exercises is that naval exercises can involve sound 
sources on more than one vessel. 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 
signals can, in special circumstances, lead (at least indirectly) to 
physical damage and mortality (e.g., Balcomb and Claridge, 2001; NOAA 
and USN, 2001; Jepson et al., 2003; Fernandez et al., 2004, 2005; 
Hildebrand, 2005; Cox et al., 2006) 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 or deaths at 
sea as a result of exposure to seismic surveys, but a few cases of 
strandings in the general area where a seismic survey was ongoing have 
led to speculation concerning a possible link between seismic surveys 
and strandings. Suggestions that there was a link between seismic 
surveys and strandings of humpback whales in Brazil (Engel et

[[Page 21641]]

al., 2004) were not well founded (IAGC, 2004; IWC, 2007). In September 
2002, there was a stranding of two Cuvier's beaked whales (Ziphius 
cavirostris) in the Gulf of California, Mexico, when the L-DEO vessel 
R/V Maurice Ewing was operating a 20-airgun, 8490-in\3\ airgun array in 
the general area. The link between the stranding and the seismic 
surveys was inconclusive and not based on any physical evidence 
(Hogarth, 2002; Yoder, 2002). Nonetheless, the Gulf of California 
incident plus the beaked whale strandings near naval exercises 
involving use of mid-frequency sonar suggests a need for caution in 
conducting seismic surveys in areas occupied by beaked whales until 
more is known about effects of seismic surveys on those species 
(Hildebrand, 2005).
    No injuries of beaked whales are anticipated during the proposed 
study because of: (1) the high likelihood that any beaked whales nearby 
would avoid the approaching vessel before being exposed to high sound 
levels; (2) the proposed monitoring and mitigation measures; and (3) 
differences between the sound sources operated by L-DEO and those 
involved in the naval exercises associated with strandings.

Possible Effects of Multibeam Echosounder (MBES) Signals

    The Simrad EM120 12-kHz MBES will be operated from the source 
vessel continuously during the planned study. Sounds from the MBES are 
very short pulses, occurring for 2-15 ms once every 5 20 s, depending 
on water depth. Most of the energy in the sound pulses emitted by this 
MBES is at frequencies near 12 kHz, and the maximum source level is 242 
dB re 1 microPa<bullet> m (rms). The beam is narrow (1[deg]) in fore-
aft extent and wide (150[deg]) in the cross-track extent. Each ping 
consists of nine successive fan-shaped transmissions (segments) at 
different cross-track angles. 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 EM120 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 2 15 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 an MBES emits a 
pulse is small. The animal would have to pass the transducer at close 
range and be swimming at speeds similar to the vessel in order to 
receive the multiple pulses that might result in sufficient exposure to 
cause TTS.
    Navy sonars that have been linked to avoidance reactions and 
stranding of cetaceans: (1) generally have longer pulse duration than 
the Simrad EM120, and (2) are often directed close to omnidirectionally 
versus more downward for the Simrad EM120. 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 naval sonar. During L-DEO'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 the area.
    Masking - Marine mammal communications will not be masked 
appreciably by the MBES signals given the low duty cycle of the 
echosounder and the brief period when an individual mammal is likely to 
be within its beam. Furthermore, in the case of baleen whales, the MBES 
signals (12 kHz) do not overlap with the predominant frequencies in the 
calls, which would avoid any significant masking.
    Behavioral Responses: Behavioral reactions of free-ranging marine 
mammals to sonar, 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 (Globicephala spp.) 
(Rendell and Gordon, 1999), and the previously-mentioned beachings by 
beaked whales. During exposure to a 21-25 kHz sonar with a source level 
of 215 dB re 1 microPa<bullet>m, gray whales reacted by orienting 
slightly away from the source and being deflected from their course by 
approximately 200 m (Frankel, 2005). When a 38-kHz echosounder and a 
150-kHz acoustic Doppler current profiler were transmitting during 
studies in the Eastern Tropical Pacific, baleen whales showed no 
significant responses, while spotted and spinner dolphins were detected 
slightly more often and beaked whales less often during visual surveys 
(Gerrodette and Pettis, 2005).
    Captive bottlenose dolphins exhibited changes in behavior when 
exposed to 1-s tonal signals at frequencies similar to those that will 
be emitted by the MBES used by L-DEO, 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 duration as compared with those 
from an MBES.
    Very few data are available on the reactions of pinnipeds to sonar 
sounds at frequencies similar to those used during seismic operations. 
Hastie and Janik (2007) conducted a series of behavioral response tests 
on two captive gray seals to determine their reactions to underwater 
operation of a 375-kHz multibeam imaging sonar that included 
significant signal components down to 6 kHz. Results indicated that the 
two seals reacted to the sonar signal by significantly increasing their 
dive durations. Because of the likely brevity of exposure to the MBES 
sounds, pinniped reactions are expected to be limited to startle or 
otherwise brief responses of no lasting consequence to the animals.
    Hearing Impairment and Other Physical Effects: Given recent 
stranding events that have been associated with the operation 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 L-DEO is quite different than sonars used for navy 
operations. Pulse duration of the MBES is very short relative to the 
naval sonars. Also, at any given location, an individual marine mammal 
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 nearhorizontally-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.
    Given the maximum source level of 242 dB re 1 microPa<bullet>m rms, 
the received level for an animal within the MBES beam 100 m (328 ft) 
below the ship would be approximately 202 dB re 1 microPa rms, assuming 
40 dB of spreading loss over 100 m (328 ft) (circular spreading). Given 
the narrow beam, only one pulse is likely to be received by a given 
animal as the ship passes overhead. The received energy level from a 
single pulse ofduration 15 ms would be about 184 dB re 1 
microPa\2\<bullet>s, i.e., 202 dB + 10 log (0.015 s). That is below the 
TTS threshold for a cetacean receiving a single non-impulse sound (195 
dB re 1 microPa\2\<bullet>s) and even further below the anticipated PTS 
threshold (215 dB re 1 microPa\2\<bullet>s) (Southall et al., 2007). In 
contrast, an animal that was only 10 m (32 ft) below the MBES when a 
ping is

[[Page 21642]]

emitted would be expected to receive a level approximately 20 dB 
higher, i.e., 204 dB re 1 microPa\2\<bullet>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 
cetaceans. As noted by Burkhardt et al., (2007, 2008), cetaceans are 
very unlikely to incur PTS from operation of scientific sonars on a 
ship that is underway.
    In the harbor seal, the TTS threshold for non-impulse sounds is 
about 183 dB re 1 microPa\2\<bullet>s, as compared with approximately 
195 dB re 1 microPa\2\<bullet>s in odontocetes (Kastak et al., 2005; 
Southall et al., 2007). TTS onset occurs at higher received energy 
levels in the California sea lion and northern elephant seal than in 
the harbor seal. A harbor seal as much as 100 m (328 ft) below the 
Langseth could receive a single MBES pulse with received energy level 
of greater than or equal to 184 dB re 1 microPa\2\<bullet>s (as 
calculated in the toothed whale subsection above) and thus could incur 
slight TTS. Species of pinnipeds with higher TTS thresholds would not 
incur TTS unless they were closer to the transducers when a sonar ping 
was emitted. However, the SEL criterion for PTS in pinnipeds (203 dB re 
1 microPa\2\<bullet>s) might be exceeded for a ping received within a 
few meters of the transducers, although the risk of PTS is higher for 
certain species (e.g., harbor seal). Given the intermittent nature of 
the signals and the narrow MBES beam, only a small fraction of the 
pinnipeds below (and close to) the ship would receive a pulse as the 
ship passed overhead.

Possible Effects of the Sub-bottom Profiler Signals

    An SBP may be operated from the source vessel at times during the 
planned study. Sounds from the sub-bottom profiler are very short 
pulses, occurring for 1 4 ms once every second. Most of the energy in 
the sound pulses emitted by the SBP is at 3.5 kHz, and the beam is 
directed downward in a narrow beam with a spacing of up to 15[deg] and 
a fan width up to 30[deg]. The sub-bottom profiler on the Langseth has 
a maximum source level of 204 dB re 1 microPa<bullet>m. Kremser et al. 
(2005) noted that the probability of a cetacean swimming through the 
area of exposure when a bottom profiler emits a pulse is small-even for 
an SBP more powerful than that on the Langseth if the animal was in the 
area, it would have to pass the transducer at close range and in order 
to be subjected to sound levels that could cause TTS.
    Masking - 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 baleen whales, 
the SBP signals do not overlap with the predominant frequencies in the 
calls, which would avoid significant masking.
    Behavioral Responses - Marine mammal behavioral reactions to other 
pulsed sound sources are discussed above, and responses to the SBP are 
likely to be similar to those for other pulsed sources if received at 
the same levels. However, the pulsed signals from the SBP are 
considerably weaker than those from the MBES. Therefore, behavioral 
responses would not be expected unless marine mammals were to approach 
very close to the source.
    Hearing Impairment and Other Physical Effects: It is unlikely that 
the SBP 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 SBP is usually 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 SBP. In 
the case of mammals that do not avoid the approaching vessel and its 
various sound sources, mitigation measures that would be applied to 
minimize effects of other sources would further reduce or eliminate any 
minor effects of the SBP.

Possible Effects of the Acoustic Release Signals

    The acoustic release transponder used to communicate with the OBS 
uses frequencies of 9 13 kHz. Once the OBS is ready to be retrieved, an 
acoustic release transponder interrogates the OBS at a frequency of 9 
11 kHz, and a response is received at a frequency of 9 13 kHz. However, 
these signals will be used very intermittently. The source level of the 
release signal is 190 dB (re 1 microPa at 1 m). An animal would have to 
pass by the OBS at close range when the signal is emitted in order to 
be exposed to any pulses at that level. The sound is expected to 
undergo a spreading loss of approximately 40 dB in the first 100 m (328 
ft). Thus, any animals located 100 m (328 ft) or more from the signal 
will be exposed to very weak signals (less than 150 dB) that are not 
expected to have any effects. The signal is used only for short 
intervals to interrogate and trigger the release of the OBS and 
consists of pulses rather than a continuous sound. Given the short 
duration use of this signal and rapid attenuation in seawater it is 
unlikely that the acoustic release signals would significantly affect 
marine mammals or sea turtles through masking, disturbance, or hearing 
impairment. Any effects likely would be negligible given the brief 
exposure at presumable low levels.

Proposed Monitoring and Mitigation Measures

Monitoring

    L-DEO proposes to sponsor marine mammal monitoring during the 
present project, in order to implement the proposed mitigation measures 
that require real-time monitoring, and to satisfy the anticipated 
monitoring requirements of the IHA. L-DEO's proposed Monitoring Plan is 
described below this section. L-DEO understands that this monitoring 
plan will be subject to review by NMFS, and that refinements may be 
required. The monitoring work described here has been planned as a 
self-contained project independent of any other related monitoring 
projects that may be occurring simultaneously in the same regions. L-
DEO is prepared to discuss coordination of its monitoring program with 
any related work that might be done by other groups insofar as this is 
practical and desirable.
Vessel-based Visual Monitoring
    Marine mammal visual observers (MMVOs) will be based aboard the 
seismic source vessel and will watch for marine mammals and turtles 
near the vessel during daytime airgun operations and during any start-
ups at night. The MMVOs will also watch for marine mammals and turtles 
near the seismic vessel for at least 30 minutes (min) prior to the 
start of airgun operations after an extended shut down. When feasible, 
MMVOs will also observe during daytime periods when the seismic system 
is not operating for comparison of sighting rates and behavior with 
versus without airgun operations. Based on the MMVOs' observations, the 
Langseth will power down the airguns or shut down the airguns when 
marine mammals are observed within or about to enter a designated 
exclusion zone (EZ). The EZ is a region in which a possibility exists 
of adverse effects on animal hearing or other physical effects.
    During seismic operations in the Endeavour MPA, at least three 
MMVOs will be based aboard the Langseth. MMVOs will be appointed by L-
DEO with NMFS concurrence. At least one MMVO, and when feasible, two

[[Page 21643]]

MMVOs, will monitor marine mammals and turtles near the seismic vessel 
during ongoing daytime operations and nighttime start ups of the 
airguns. Use of two simultaneous observers will increase the proportion 
of the animals present near the source vessel that are detected. 
MMVO(s) will be on duty in shifts of duration no longer than 4 h. Other 
crew will also be instructed to assist in detecting marine mammals and 
turtles and implementing mitigation requirements (if feasible). Before 
the start of the seismic survey the crew will be given additional 
instruction regarding how to do so.
    The Langseth is a suitable platform for marine mammal and turtle 
observations. When stationed on the observation platform, the eye level 
will be approximately 18 m (59 ft) above sea level, and the observer 
will have a good view around the entire vessel. During daytime, the 
MMVOs will scan the area around the vessel systematically with reticle 
binoculars (e.g., 7 50 Fujinon), Big-eye binoculars (25 150), and with 
the naked eye. During darkness, night vision devices (NVDs) will be 
available (ITT F500 Series Generation 3 binocularimage intensifier or 
equivalent), when required. Laser rangefinding binoculars (Leica LRF 
1200 laser rangefinder or equivalent) will be available to assist with 
distance estimation. Those are useful in training observers to estimate 
distances visually, but are generally not useful in measuring distances 
to animals directly; that is done primarily with the reticles in the 
binoculars.
    The vessel-based monitoring will provide data to estimate the 
numbers of marine mammals exposed to various received sound levels, to 
document any apparent disturbance reactions or lack thereof, and thus 
to estimate the numbers of mammals potentially ``taken'' by harassment. 
It will also provide the information needed in order to power down or 
shut down the airguns at times when mammals and turtles are present in 
or near the safety radii. When a 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 airguns or vessel (e.g., none, avoidance, 
approach, paralleling, etc.), and behavioral pace.
    2. Time, location, heading, speed, activity of the vessel, 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 observations and power-downs or shut downs will be recorded in 
a standardized format. Data will be entered into a custom database 
using a notebook computer. The accuracy of the data entry will be 
verified by computerized validity data checks as the data are entered 
and by subsequent manual checking of the database. 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.
    Results from the vessel-based observations will provide:
    1. The basis for real-time mitigation (airgun power-down or shut-
down).
    2. Information needed to estimate the number of marine mammals 
potentially taken by harassment, which must be reported to NMFS per 
terms of MMPA authorizations or regulations.
    3. Data on the occurrence, distribution, and activities of marine 
mammals and turtles in the area where the seismic study is conducted.
    4. Data on the behavior and movement patterns of marine mammals and 
turtles seen at times with and without seismic activity.
Passive Acoustic Monitoring
    Passive acoustic monitoring (PAM) will take place to complement the 
visual monitoring program. Visual monitoring typically is not effective 
during periods of bad weather or at night, and even with good 
visibility, is unable to detect marine mammals when they are below the 
surface or beyond visual range. Acoustical monitoring can be used in 
addition to visual observations to improve detection, identification, 
localization, and tracking of cetaceans. The acoustic monitoring will 
serve to alert visual observers (if on duty) when vocalizing cetaceans 
are detected. It is only useful when marine mammals call, but it can be 
effective either by day or by night, and does not depend on good 
visibility. It will be monitored in real time so that the visual 
observers can be advised when cetaceans are detected. When bearings 
(primary and mirror-image) to calling cetacean(s) are determined, the 
bearings will be relayed to the visual observer to help him/her sight 
the calling animal(s).
    The PAM system consists of hardware (i.e., hydrophones) and 
software. The ``wet end'' of the system consists of a low-noise, towed 
hydrophone array that is connected to the vessel by a ``hairy'' faired 
cable. The array will be deployed from a winch located on the back 
deck. A deck cable will connect from the winch to the main computer lab 
where the acoustic station and signal conditioning and processing 
system will be located. The lead-in from the hydrophone array is 
approximately 400 m (1312 ft) long, and the active part of the 
hydrophone array is approximately 50 m (164 ft) long. The hydrophone 
array is typically towed at depths of 20 m (66 ft) to 30 m (98 ft).
    The towed hydrophones will be monitored 24 h per day while at the 
seismic survey area during airgun operations, and during most periods 
when the Langseth is underway while the airguns are not operating. One 
MMO will monitor the acoustic detection system at any one time, by 
listening to the signals from two channels via headphones and/or 
speakers and watching the real-time spectrographic display for 
frequency ranges produced by cetaceans. MMOs monitoring the acoustical 
data will be on shift for 1 6 h at a time. Besides the visual MMOs, an 
additional MMO with primary responsibility for PAM will also be aboard. 
All MMOs are expected to rotate through the PAM position, although the 
most experienced with acoustics will be on PAM duty more frequently.
    When a vocalization is detected while visual observations are in 
progress, the acoustic MMO will contact the visual MMO immediately, to 
alert him/her to the presence of cetaceans (if they have not already 
been seen), and to allow a power down or shut down to be initiated, if 
required. The information regarding the call will be entered into a 
database. The data to be entered include an acoustic encounter 
identification number, whether it was linked with a visual sighting, 
date, time when first and last heard and whenever any additional 
information was recorded, position and water depth when first detected, 
bearing if determinable, species or species group (e.g., unidentified 
dolphin, sperm whale), types and nature of sounds heard (e.g., clicks, 
continuous, sporadic, whistles, creaks, burst pulses, strength of 
signal, etc.), and any other notable information. The acoustic 
detection can also be recorded for further analysis.

Mitigation

    L-DEO's mitigation procedures are based on protocols used during 
previous L-DEO seismic research cruises as approved by NMFS, and on 
best practices recommended in Richardson et al. (1995), Pierson et al. 
(1998), and Weir and Dolman (2007). The measures

[[Page 21644]]

are described in detail below this section.

Proposed Exclusion Zones

    As noted earlier, L-DEO modeled received sound levels for the 36-
airgun array and for a single 1900LL 40-in\3\ airgun (which will be 
used during power downs), in relation to distance and direction from 
the airguns. Based on the modeling for deep water, the distances from 
the source where sound levels are predicted to be 190, 180, and 160 dB 
re 1 microPa (rms) were determined (Table 1). The 180- and 190-dB radii 
vary with tow depth of the airgun array and range up to 1220 m (4002 
ft) and 380 m (1246 ft), respectively. The 180- and 190-dB levels are 
shut-down criteria applicable to cetaceans and pinnipeds, respectively, 
as specified by NMFS (2000); these levels were used to establish the 
exclusion zones (EZ). If the MMO detects marine mammal(s) or turtle(s) 
within or about to enter the appropriate safety radii, the airguns will 
be powered down (or shut down if necessary) immediately.
Mitigation During Operations
    Mitigation measures that will be adopted during the L-DEO survey 
include: (1) speed or course alteration, provided that doing so will 
not compromise operational safety requirements; (2) power-down 
procedures; (3) shut-down procedures; (4) ramp-up procedures; and (5) 
special procedures for species of particular concern.
    Speed or Course Alteration - If a marine mammal or sea turtle is 
detected outside the safety zone and, based on its position and the 
relative motion, is likely to enter the safety zone, the vessel's speed 
and/or direct course may be changed. This would be done if practicable 
while minimizing the effect on the planned science objectives. The 
activities and movements of the marine mammal or sea turtle (relative 
to the seismic vessel) will then be closely monitored to determine 
whether the animal is approaching the applicable safety zone. If the 
animal appears likely to enter the safety zone, further mitigative 
actions will be taken, i.e., either further course alterations or a 
power down or shut down of the airguns. Typically, during seismic 
operations that use hydrophone streamers, the source vessel is unable 
to change speed or course and one or more alternative mitigation 
measures (see below) will need to be implemented.
    Power-down Procedures - A power-down involves decreasing the number 
of airguns in use such that the radius of the 180-dB (or 190-dB) zone 
is decreased to the extent that marine mammals or turtles are no longer 
in or about to enter the safety zone. A power-down of the airgun array 
can also occur when the vessel is moving from one seismic line to 
another. During a power-down for mitigation, one airgun will be 
operated. The continued operation of one airgun is intended to alert 
marine mammals and turtles to the presence of the seismic vessel in the 
area. In contrast, a shut-down occurs when all airgun activity is 
suspended.
    If a marine mammal or turtle is detected outside the EZ but is 
likely to enter the EZ, and if the vessel's speed and/or course cannot 
be changed to avoid having the animal enter the safety radius, the 
airguns will be powered down before the animal is within the EZ. 
Likewise, if a mammal or turtle is already within the EZ when first 
detected, the airguns will be powered down immediately. During a power-
down of the airgun array, the 40-in\3\ airgun will be operated. If a 
marine mammal or turtle is detected within or near the smaller EZ 
around that single airgun (Table 1), it will be shut down (see next 
subsection).
    Following a power-down, airgun activity will not resume until the 
marine mammal or turtle has cleared the EZ. The animal will be 
considered to have cleared the EZ if it: (1) is visually observed to 
have left the EZ; or (2) has not been seen within the zone for 15 min 
in the case of small odontocetes; or (3) has not been seen within the 
zone for 30 min in the case of mysticetes and large odontocetes, 
including sperm, pygmy sperm, dwarf sperm, and beaked whales; or (4) 
the vessel has moved outside the EZ for turtles, i.e., approximately 5 
to 20 min, depending on the sighting distance, vessel speed, and tow-
depth.
    During airgun operations following a power down (or shut down) 
whose duration has exceeded the limits specified above, the airgun 
array will be ramped up gradually (see below).
    Shut-down Procedures - During a power down, the operating airgun 
will be shut down if a marine mammal or turtle is seen within or 
approaching the EZ for a single airgun. Shut-downs will be implemented: 
(1) if an animal enters the exclusion zone of the single airgun after a 
power-down has been initiated, or (2) if an animal is initially seen 
within the exclusion zone of a single airgun when more than one airgun 
(typically the full array) is operating.
    Airgun activity will not resume until the marine mammal or turtle 
has cleared the EZ, or until the visual marine mammal observer (MMVO) 
is confident that the animal has left the vicinity of the vessel. 
Criteria for judging that the animal has cleared the EZ will be as 
described in the preceding subsection.
    The airguns will be shut down if a North Pacific right whale is 
sighted from the vessel, even if it is located outside the EZ, because 
of the rarity and sensitive status of this species.
    Ramp-up Procedures - A ramp-up procedure will be followed when the 
airgun array begins operating after a specified period without airgun 
operations or when a power-down has exceeded that period. It is 
proposed that, for the present cruise, this period would be 
approximately 9 min. This period is based on the largest modeled 180-dB 
radius for the 36-airgun array (see Table 1) in relation to the planned 
speed of the Langseth while shooting the airguns. Similar periods 
(approximately 8 10 min) were used during previous L-DEO surveys.
    Ramp-up will begin with the smallest gun in the array (40 in\3\). 
Airguns will be added in a sequence such that the source level of the 
array will increase in steps not exceeding 6 dB per 5-min period over a 
total duration of about 30 - 40 min. During ramp-up, the MMVOs will 
monitor the safety zone and if marine mammals or turtles are sighted, a 
course/speed change, power down, or shut down will be implemented as 
though the full array were operational.
    If the complete EZ has not been visible for at least 30 min prior 
to the start of operations in either daylight or nighttime, ramp-up 
will not commence unless at least one airgun (40 in\3\ or similar) has 
been operating during the interruption of seismic survey operations. 
Given these provisions, it is likely that the airgun array will not be 
ramped up from a complete shut-down at night or in thick fog, because 
the outer part of the EZ for that array will not be visible during 
those conditions. If one airgun has operated during a power-down 
period, ramp-up to full power will be permissible at night or in poor 
visibility, on the assumption that marine mammals and turtles will be 
alerted to the approaching seismic vessel by the sounds from the single 
airgun and could move away if they choose. Ramp-up of the airguns will 
not be initiated if a sea turtle or marine mammal is sighted within or 
near the applicable zones during the day or close to the vessel at 
night.
    Shutdown if Injured or Dead Whale is Found - In the unanticipated 
event that any cases of marine mammal injury or mortality are found and 
are judged likely to have resulted from these activities, L-DEO will 
cease operating seismic airguns and report the incident

[[Page 21645]]

to the Office of Protected Resources, NMFS immediately.

Reporting

    L-DEO will submit a report to NMFS within 90 days after the end of 
the cruise. The report will describe the operations that were conducted 
and sightings of marine mammals and turtles near the operations. The 
report will provide full documentation of methods, results, and 
interpretation pertaining to all monitoring. The 90-day report will 
summarize the dates and locations of seismic operations, and all marine 
mammal and turtle sightings (dates, times, locations, activities, 
associated seismic survey activities). The report will also include 
estimates of the number and nature of exposures that could result in 
``takes'' of marine mammals by harassment or in other ways.
    All injured or dead marine mammals (regardless of cause) must be 
reported to NMFS as soon as practicable. Report should include species 
or description of animal, condition of animal, location, time first 
found, observed behaviors (if alive) and photo or video, if available.

Estimated Take by Incidental Harassment

    Because of the mitigation measures that will be required and the 
likelihood that some cetaceans will avoid the area around the operating 
airguns of their own accord, NMFS does not expect any marine mammals to 
approach the sound source close enough to be injured (Level A 
harassment). All anticipated takes would be ``takes by Level B 
harassment'', as described previously, involving temporary behavioral 
modifications or low-level physiological effects.
    Estimates of the numbers of marine mammals that might be affected 
are based on consideration of the number of marine mammals that could 
be disturbed appreciably by approximately 1800 km (1118 mi) of seismic 
surveys during the proposed seismic program in the Endeavor MPA.
    It is assumed that, during simultaneous operations of the airgun 
array and the other sources, any marine mammals close enough to be 
affected by the MBES or SBP would already be affected by the airguns. 
However, whether or not the airguns are operating simultaneously with 
the other sources, marine mammals are expected to exhibit no more than 
short-term and inconsequential responses to the MBES and SBP given 
their characteristics (e.g., narrow downward-directed beam) and other 
considerations described in section I of L-DEO's application. Such 
reactions are not considered to constitute ``taking'' (NMFS, 2001). 
Therefore, no additional allowance is included for animals that might 
be affected by sound sources other than airguns.

Density Estimates

    There is very little information on the cetaceans that occur in 
deep water off the west coast of Vancouver Island, but the waters off 
Oregon and Washington have been studied in some detail (e.g., Green et 
al., 1992, 1993; Barlow, 1997, 2003; Barlow and Taylor, 2001; 
Calambokidis and Barlow, 2004; Barlow and Forney, 2007). The primary 
data used to provide densities for the proposed project area off 
southwestern British Columbia (BC) were obtained from the 1996, 2001, 
and 2005 NMFS/SWFSC ``ORCAWALE'' or ``CSCAPE'' ship surveys off Oregon/
Washington, as synthesized by Barlow and Forney (2007). The surveys 
took place up to approximately 550 km (341 mi) offshore from June or 
July through November or December. Thus, the surveys included effort in 
coastal, shelf/slope, and offshore water, and they encompass the August 
September period for the proposed study. Systematic, offshore survey 
data for pinnipeds are more limited. The most comprehensive such 
studies are reported by Bonnell et al., (1992) based on systematic 
aerial surveys conducted in 1989 1990.
    The waters off the west coast of Vancouver Island are included in 
the same ecological province as Oregon/Washington, the California 
Coastal Province (Longhurst, 2007). Thus, information on cetaceans from 
Oregon/Washington is relevant to the proposed offshore study area far 
offshore of BC. Although densities for BC are available for some 
cetacean species (see Williams and Thomas 2007), these are for inshore 
coastal waters and would not be representative of the densities 
occurring in offshore areas. Although the cetacean densities based on 
data from Barlow and Forney (2007) better reflect those that will be 
encountered during the ETOMO study, the actual densities in the 
Endeavour MPA are expected to be lower still, as the survey effort off 
Oregon/Washington covered offshore as well as shelf and coastal waters, 
and it included sightings for summer and fall.
    Oceanographic conditions, including occasional El Nino and La Nina 
events, influence the distribution and numbers of marine mammals 
present in the NEPO, 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; Becker, 2007). 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.

Potential Number of Exposures to Sound Levels at or above 160 dB

    L-DEO's ``best estimate'' of the potential number of exposures of 
cetaceans, absent any mitigation measures, to seismic sounds with 
received levels at or above 160 dB re 1 microPa (rms) is 8,624 (Table 
2). It is assumed that marine mammals exposed to airgun sounds this 
strong might change their behavior sufficiently to be considered 
``taken by harassment''.
    The number of potential exposures to sound levels at or above 160 
dB re 1 microPa (rms) were calculated by multiplying the expected 
average species density (see section VII of L-DEO's application) times 
the anticipated minimum area (7302 km2, 4537 mi2) to be ensonified to 
that level during airgun operations including overlap.
    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 buffer around each seismic line, and then calculating 
the total area within the buffers. Areas where overlap occurred 
(because of closely-spaced lines) were included when estimating the 
number of exposures.

Number of Individual Cetaceans Exposed to Sound Levels at or above 160 
dB

    L-DEO's ``best estimate'' of the potential number of different 
individuals that could be exposed to airgun sounds with received levels 
at or above 160 dB re 1 microPa (rms) on one or more occasions is 
1,748. That total includes 22 baleen whales, 17 of which are considered 
endangered under the ESA: six humpback whales, two blue whales, one sei 
whale, and eight fin whales, which would represent small numbers of the 
regional populations (Table 2). Ten sperm whales and 19 beaked whales 
could be exposed during the survey as well (Table 2).
    Based on numbers of animals encountered during previous L-DEO 
seismic surveys, the likelihood of the successful implementation of the 
required mitigation measures, and the likelihood that some animals will 
avoid the area around the operating airguns, NMFS believes that L-DEO's 
airgun seismic testing program may result in

[[Page 21646]]

the Level B harassment of some lower number of individual marine 
mammals (a few times each) than is indicated by the column titled, 
Number of Individuals Exposed to [gteqt]160 dB (Request) in Table 2. L-
DEO has asked for authorization for take of their best estimate of 
numbers for each species. Though NMFS believes that take of the 
requested numbers is unlikely, we still find these numbers small 
relative to the population sizes.

Potential Effects on Habitat

    The proposed seismic survey will not result in any permanent impact 
on habitats used by marine mammals, or to the food sources they use. 
The main impact issue associated with the proposed activity will be 
temporarily elevated noise levels and the associated direct effects on 
marine mammals.
    The Langseth will deploy 16 OBS in the vent field grid (see Figure 
1 of L-DEO's application), and will deploy another 48 OBS throughout 
the remaining study area in the Endeavour MPA. L-DEO proposes to use 
two different types of OBS: (1) the WHOI ``D2'' OBS, which has an 
anchor made of hot-rolled steel with dimensions 2.5 x 30.5 x 38.1 cm; 
and (2) the LC4x4, which consists of a an anchor with a 1 m2 piece of 
steel grating. These OBS anchors will remain upon equipment recovery.
    Although OBS placement may disrupt a very small area of seafloor 
habitat and may disturb benthic invertebrates, the impacts are expected 
to be localized and transitory. The vessel will deploy the OBS in such 
a way that creates the least disturbance to the area. The vent area is 
dynamic, and the natural variability within the system is high; 
toppling and regrowth of sulphide structures, and death of assemblages 
are common (Tunnicliffe and Thomson, 1999). Thus, it is not expected 
that the placement of OBS would have adverse effects beyond naturally 
occurring changes in this environment, and any effects of the planned 
activity on marine mammal habitats and food resources are expected to 
be negligible.

Potential Effects on Fish

    Existing information on the impacts of seismic surveys on marine 
fish and invertebrate populations is very limited (See Appendix D of L-
DEO's EA) and the vast majority of the data are in the form of reports 
and other documents that have not been peer reviewed (Popper and 
Hastings, 2009).
    There are three types of potential effects of exposure to seismic 
surveys: (1) pathological, (2) physiological, and (3) behavioral.
    Pathological Effects - Pathological effects involve lethal and 
temporary or permanent sub-lethal injury. 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 D of L-DEO's EA). For a given 
sound to result in hearing loss, the sound must exceed, by some 
substantial 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 are unknown; however, they 
likely depend 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. 
McCauley et al. (2003), found that exposure to airgun sound caused 
observable anatomical damage to the auditory maculae of ``pink 
snapper'' (Pagrusauratus). This damage in the ears had not been 
repaired in fish sacrificed and examined almost two months after 
exposure. O n the other hand, Popper et al. (2005) documented only TTS 
(as determined by auditory brainstem response) in two of three fish 
species 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\<bullet>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 airguns [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 less than 2 m (6.5 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).
    According to Buchanan et al. (2004), for the types of seismic 
airguns and arrays involved with the proposed program, the pathological 
(mortality) zone for fish would be expected to be within a few meters 
of the seismic source. Numerous other studies provide examples of no 
fish mortality upon exposure to seismic sources (Falk and Lawrence, 
1973; Holliday et al., 1987; La Bella et al., 1996; Santulli et al., 
1999; McCauley et al., 2000a,b, 2003; Bjarti, 2002; Hassel et al. 2003; 
Popper et al., 2005).
    Physiological Effects - Physiological effects involve temporary and 
permanent primary and secondary stress responses. Cellular and/or 
biochemical responses of fish to acoustic stress such as changes in 
levels of enzymes and proteins could potentially 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,b). 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 D of L-DEO's EA).
    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 
survey sound) on fish behavior have been conducted on both uncaged and 
caged individuals (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; Lokkeborg, 1991; Skalski et al., 1992; Engas et al., 1996). In 
other airgun experiments, there was no change in catch per unit effort 
(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 Slotte et al. 
(2004).
    In general, any adverse effects on fish behavior or fisheries 
attributable to

[[Page 21647]]

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.

Potential Impacts 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. The 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 E of L-DEO's EA).
    Pathological Effects - For the type of airgun array planned for the 
proposed program, the pathological (mortality) zone for crustaceans and 
cephalopods is expected to be within a few meters 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 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.
    Benthic invertebrates in the Endeavor MPA are not expected to be 
affected by seismic operations, as sound levels from the airguns will 
diminish dramatically by the time the sound reaches the ocean floor at 
a depth of approximately 2250 m (7382 ft).

Negligible Impact Determination

    NMFS has preliminarily determined, provided that the aforementioned 
mitigation and monitoring measures are implemented, that the impact of 
conducting a seismic program in the northeast Pacific Ocean may result, 
at worst, in a temporary modification in behavior and/or low-level 
physiological effects (Level B Harassment) of small numbers of certain 
species of marine mammals. While behavioral and avoidance reactions may 
be made by these species in response to the resultant noise from the 
airguns, these behavioral changes are expected to have a negligible 
impact on the affected species and stocks of marine mammals.
    While the number of potential incidental harassment takes will 
depend on the distribution and abundance of marine mammals in the area 
of seismic operations, the number of potential harassment takings is 
estimated to be relatively small in light of the population size (see 
Table 2). NMFS anticipates the actual take of individuals to be lower 
than the numbers depicted in the table, because those numbers do not 
reflect either the implementation of the mitigation numbers or the fact 
that some animals will avoid the sound at levels lower than those 
expected to result in harassment. Additionally, mitigation measures 
require that the Langseth avoid any areas where marine mammals are 
concentrated.
    In addition, no take by death and/or serious injury is anticipated, 
and the potential for temporary or permanent hearing impairment will be 
avoided through the incorporation of the required mitigation measures 
described in this document. This conclusion is supported by: (1) the 
likelihood that, given sufficient notice through slow ship speed and 
ramp-up of the seismic array, marine mammals are expected to move away 
from a noise source that it is annoying prior to its becoming 
potentially injurious; (2) TTS is unlikely to occur, especially in 
odontocetes, until levels above 180 dB re 1 microPa (rms) are reached; 
(3) the fact that injurious levels of sound are only likely very close 
to the vessel; and (4) the monitoring program developed to avoid injury 
will be sufficient to detect (using visual detection and PAM), with 
reasonable certainty, all marine mammals within or entering the 
identified safety zones.

Endangered Species Act (ESA)

    Under section 7 of the ESA, the National Science Foundation (NSF) 
has begun consultation on this proposed seismic survey. NMFS will also 
consult internally 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 an IHA.

National Environmental Policy Act (NEPA)

    On September 22, 2005 (70 FR 55630), NSF published a notice of 
intent to prepare a Programmatic Environmental Impact Statement/
Overseas Environmental Impact Statement (EIS/OES) to evaluate the 
potential environmental impacts associated with the use of seismic 
sources in support of NSF-funded research by U.S. academic scientists. 
NMFS agreed to be a cooperating agency in the preparation of the EIS/
OEIS. This EIS/OEIS has not been completed. Therefore, in order to meet 
NSF's and NMFS' NEPA requirements for the proposed activity and 
issuance of an IHA to L-DEO, the NSF has prepared an Environmental 
Assessment of a Marine Geophysical Survey by the Langseth in the 
northeast Pacific Ocean in the Endeavor MPA. NMFS is reviEwing that 
document and will either adopt NSF's EA or conduct a separate NEPA 
analysis, as necessary, prior to making a determination of the issuance 
of the IHA. NMFS has posted NSF's EA on its website at http://www.nmfs.noaa.gov/pr/permits/incidental.htm#applications.

Preliminary Conclusions

    Based on the preceding information, and provided that the proposed 
mitigation and monitoring are incorporated, NMFS has preliminarily 
concluded that the proposed activity will incidentally take, by level B 
behavioral harassment only, small numbers of marine mammals. There is 
no subsistence harvest of marine mammals in the proposed research area; 
therefore, there will be no impact of the activity on the availability 
of the species or stocks of marine mammals for subsistence uses. No 
take by Level A harassment (injury) or death is anticipated and 
harassment takes should be at the lowest level practicable due to 
incorporation of the mitigation measures proposed in this document.

Proposed Authorization

    NMFS proposes to issue an IHA to L-DEO for a marine seismic survey 
in the northeast Pacific Ocean during August - October 2009, provided 
the previously mentioned mitigation, monitoring, and reporting 
requirements are incorporated.


[[Page 21648]]


    Dated: May 4, 2009.
Helen M. Golde,
Deputy Director, Office of Protected Resources, National Marine 
Fisheries Service.
[FR Doc. E9-10821 Filed 5-7-09; 8:45 am]
BILLING CODE 3510-22-S


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