[Federal Register Volume 73, Number 246 (Monday, December 22, 2008)]
[Notices]
[Pages 78294-78317]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E8-30365]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

RIN 0648-XL89


Incidental Takes of Marine Mammals During Specified Activities; 
Marine Geophysical Survey in Southeast Asia, March-July 2009

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

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

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

SUMMARY:  NMFS has received an application from 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 marine 
seismic survey in Southeast (SE) Asia during March-July 2009. Pursuant 
to the Marine Mammal Protection Act (MMPA), NMFS requests comments on 
its proposal to authorize L-DEO to incidentally take, by Level B 
harassment only, small numbers of marine mammals during the 
aforementioned activity.

DATES:  Comments and information must be received no later than January 
21, 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 [email protected]. Comments sent via 
e-mail, including all attachments, must not exceed a 10-megabyte file 
size.
    A copy of the application containing a list of the references used 
in this document may be obtained by writing to the address specified 
above, telephoning

[[Page 78295]]

the contact listed below (see FOR FURTHER INFORMATION CONTACT), or 
visiting the internet at: http://www.nmfs.noaa.gov/pr/permits/incidental.htm.
    Documents cited in this notice may be viewed, by appointment, 
during regular business hours, at the aforementioned address.

FOR FURTHER INFORMATION CONTACT:  Howard Goldstein or Ken Hollingshead, 
Office of Protected Resources, NMFS, (301) 713-2289.

SUPPLEMENTARY INFORMATION: Background
    Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 et seq.) 
direct the Secretary of Commerce to allow, upon request, the 
incidental, but not intentional, taking of marine mammals by United 
States citizens who engage in a specified activity (other than 
commercial fishing) within a specified geographical region if certain 
findings are made and either regulations are issued or, if the taking 
is limited to harassment, a notice of a proposed authorization is 
provided to the public for review.
    Authorization for incidental taking shall be granted if NMFS finds 
that the taking will have a negligible impact on the species or 
stock(s), will not have an unmitigable adverse impact on the 
availability of the species or stock(s) for subsistence uses, and if 
the permissible methods of taking and requirements pertaining to the 
mitigation, monitoring and reporting of such takings are set forth. 
NMFS has defined ``negligible impact'' in 50 CFR 216.103 as ``...an 
impact resulting from the specified activity that cannot be reasonably 
expected to, and is not reasonably likely to, adversely affect the 
species or stock through effects on annual rates of recruitment or 
survival.''
    Section 101(a)(5)(D) of the MMPA established an expedited process 
by which citizens of the United States can apply for an authorization 
to incidentally take small numbers of marine mammals by harassment. 
Except with respect to certain activities not pertinent here, the MMPA 
defines ``harassment'' as:
    any act of pursuit, torment, or annoyance which (i) has the 
potential to injure a marine mammal or marine mammal stock in the 
wild [``Level A harassment'']; or (ii) has the potential to disturb 
a marine mammal or marine mammal stock in the wild by causing 
disruption of behavioral patterns, including, but not limited to, 
migration, breathing, nursing, breeding, feeding, or sheltering 
[``Level B harassment''].
    Section 101(a)(5)(D) establishes a 45-day time limit for NMFS= 
review of an application followed by a 30-day public notice and comment 
period on any proposed authorizations for the incidental harassment of 
small numbers of marine mammals. Within 45 days of the close of the 
comment period, NMFS must either issue or deny issuance of the 
authorization.

Summary of Request

    On October 27, 2008, NMFS received an application from L-DEO for 
the taking, by Level B harassment only, of small numbers of marine 
mammals incidental to conducting, under cooperative agreement with the 
National Science Foundation (NSF), a marine seismic survey in SE Asia. 
The funding for the Taiwan Integrated Geodynamics Research (TAIGER) 
survey is provided by the NSF. The proposed survey will encompass the 
area 17 30'-26 30' N, 113 30'-126 E within the Exclusive Economic Zones 
(EEZ) of Taiwan, China, Japan, and the Philippines, and on the high 
seas, and is scheduled to occur from March 21 to July 14, 2009. Some 
minor deviation from these dates is possible, depending on logistics 
and weather.
    Taiwan is one of only a few sites of arc-continent collision 
worldwide; and one of the primary tectonic environments for large scale 
mountain building. The primary purpose of the TAIGER project is to 
investigate the processes of mountain building, a fundamental set of 
processes which plays a major role in shaping the face of the Earth. 
The vicinity of Taiwan is particularly well-suited for this type of 
study, because the collision can be observed at different stages of its 
evolution, from incipient, to mature, and finally to post-collision.
    As a result of its location in an ongoing tectonic collision zone, 
Taiwan experiences a great number of earthquakes, most are small, but 
many are large and destructive. This project will provide a great deal 
of information about the nature of the earthquakes around Taiwan and 
will lead to a better assessment of the earthquake hazards in the area. 
The information obtained from this study will help the people and the 
earthquake hazards in the area. The information obtained from this 
study will help the people and government of Taiwan to better prepare 
for future seismic events and may thus mitigate some of the loss of 
life and economic disruptions that will inevitably occur.
    The proposed action is planned to take place in the territorial 
seas and EEZ's of foreign nations, and will be continuous with the 
activity that takes place on the high seas. NMFS does not authorize the 
incidental take of marine mammals in the territorial seas of foreign 
nations, as the MMPA does not apply in those waters. However, NMFS 
still needs to calculate the level of incidental take in territorial 
seas as part of the proposed issuance of an IHA in regards to NMFS' 
analysis of small numbers and negligible impact determination.

Description of the Specified Activity

    The planned survey will involve one source vessel, the R/V Marcus 
G. Langseth (Langseth), which will occur in SE Asia. The Langseth will 
deploy an array of 36 airguns (6,600 in\3\) as an energy source at a 
tow depth of 6-9 m (20-30 ft). The receiving system will consist of a 
hydrophone streamer and approximately 100 ocean bottom seismometers 
(OBSs). The Langseth will deploy an 8 km (5 mi) long streamer for most 
transects requiring a streamer; however, a shorter streamer (500 m to 
2km or 1,640 ft to 1.2 mi) will be used during surveys in Taiwan 
(Formosa) Strait. As the airgun array is towed along the survey lines, 
the hydrophone streamer will receive the returning acoustic signals and 
transfer the data to the on-board processing system. The OBSs record 
the returning acoustic signals internally for later analysis. The OBSs 
to be used for the TAIGER program will be deployed and retrieved 
numerous times by a combination of 4 or 5 Taiwanese support vessels, as 
well as the Langseth. The Langseth will also retrieve 20 OBSs that were 
deployed in the study area during previous years to record earthquake 
activity.
    Approximately 100 OBSs will be deployed during the survey. OBSs 
will likely be deployed and retrieved by the Langseth as well as a 
combination of 4 to 5 Taiwanese vessels. The Taiwanese vessels to be 
used include two 30 m (98.4 ft) vessels (the R/V Ocean Researcher 2 and 
the R/V Ocean Researcher 3) and two vessels greater than 60 m (196.8 
ft) in length (R/V Fisheries Research I and the Navy ship Taquan). The 
R/V Ocean Research I may also be used if the Langseth is not used to 
deploy OBSs. The OBS deployment spacing will vary depending on the 
number of instruments available and shiptime. The nominal spacing is 15 
km (9.3 mi), but this will vary from as little as 5 km (3.1 mi) to 
perhaps as much as 25 km (15.5 mi). The OBSs will be deployed and 
recovered several (2 to 4) times. 60 of the 100 OBSs may be deployed 
from the Langseth. All OBSs will be retrieved at the end of the study.
    Up to 3 different types of OBSs may be used during the 2009 
program. The Woods Hole Oceanographic Institution (WHOI) ``D2'' OBS has 
a height of

[[Page 78296]]

approximately 1 m (3.3 ft) and a maximum diameter of 50 cm. The anchor 
is made of hot-rolled steel and weighs 23 kg (50.7 lbs). The anchor 
dimensions are 2.5 x 30.5 x 38.1 cm. The LC4x4 OBS from the Scripps 
Institution of Oceanography (SIO) has a volume of approximately 1 m\3\ 
(3.3 ft\2\), with an anchor that consists of a large piece of steel 
grating (approximately 1 m\2\ or 3.3 ft\2\). Taiwanese OBSs will also 
be used; their anchor is in the shape of an 'x' with dimensions of 51-
76 cm\2\ (1.7-2.5 ft\2\). 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. The burn 
wire release assembly is then activated, and the instrument is released 
from the anchor to float to the surface.
    The planned seismic survey will consist of approximately 15,902 km 
(9,881 mi) of transect lines within the South and East China Seas as 
well as the Philippine Sea, with the majority of the survey effort 
occurring in the South China Sea. The survey will take place in water 
depths ranging from approximately 25 to 6,585 m (82-21,598 ft), but 
most of the survey effort (approximately 80 percent) will take place in 
water greater than 1,000 m (3,280 ft), 13 percent will take place in 
intermediate depth waters (100-1,000 m or 328-3,280 ft), and 7 percent 
will occur in shallow depth water (less than 100 m or 328 ft).
    All planned geophysical data acquisition activities will be 
conducted by L-DEO with onboard assistance by the scientists who have 
proposed the study. The scientific team consists of Dr. Francis Wu 
(State University of New York at Binghamton) and Dr. Kirk McIntosh 
(University of Texas at Austin, Institute of Geophysics). The vessel 
will be self-contained, and the crew will live aboard the vessel for 
the entire cruise.
    In addition to the operations of the airgun array, a 12 kHz Simrad 
EM 120 multibeam echosounder (MBES) and a 3.5 kHz sub-bottom profiler 
(SBP) will be operated from the Langseth continuously throughout the 
TAIGER cruise.

Vessel Specifications

    The Langseth has a length of 71.5 m (234.6 ft), a beam of 17 m 
(55.8 ft), and a maximum draft of 5.9 m (19.4 ft). The ship was 
designed as a seismic research vessel, with a propulsion system 
designed to be as quiet as possible to avoid interference with the 
seismic signals. The ship is powered by two Bergen BRG-6 diesel 
engines, each producing 3,550 hp, that drive the two propellers 
directly. Each propeller has 4 blades, and the shaft typically rotates 
at 750 rpm. The vessel also has an 800 hp bowthruster. The operation 
speed during seismic acquisition is typically 7.4-9.3 km/hr (4-5 kt). 
When not towing seismic survey gear, the Langseth can cruise at 20-24 
km/hr (11-13 kt). When the Langseth is towing the airgun array as well 
as the hydrophone streamer, the turning rate of the vessel is limited 
to 5 degrees per minute. Thus, the maneuverability of the vessel is 
limited during operations with the streamer. The Langseth has a range 
of 25,000 km (15,534 mi). The Langseth will also serve as the platform 
from which vessel-based marine mammal observers (MMOs) will watch for 
animals before and during airgun operations.

Acoustic Source Specifications

Seismic Airguns
    During the proposed survey, the airgun array to be used will 
consist of 36 airguns, with a total volume of approximately 6,600 
in\3\. The airgun array will consist of a mixture of Bolt 1500LL and 
1900LL airguns. The airguns array will be configured as 4 identical 
linear arrays or ``strings'' (see Figure 2 in L-DEO's application). 
Each string will have 10 airguns; the first and last airguns in the 
strings are spaced 16 m (52.5 ft) apart. Nine airguns in each string 
will be fired simultaneously, while the tenth is kept in reserve as a 
spare, to be turned on in case of failure of another airgun. The 4 
airgun strings will be distributed across an approximate area of 24 x 
16 m (78.7 x 52.5 ft) behind the Langseth and will be towed 
approximately 140 m (459 ft) behind the vessel. The shot interval will 
be relatively short (approximately 25-50 m or 82-164 ft or 10-25 s) for 
multi-channel seismic surveying with the hydrophone streamer, and 
relatively long (approximately 100-125 m or 328-410 ft or 45-60 s) when 
recording data on the OBSs. The firing pressure of the array is 1,900 
psi. During firing, a brief (approximately 0.1 s) pulse of sound is 
emitted. The airguns will be silent during the intervening periods.
    The tow depth of the array will be 6-9 m (20-30 ft). The depth at 
which the source is towed (particularly a large source) affects the 
maximum near-field output and the shape of its frequency spectrum. If 
the source is towed at 9 m (30 ft), the effective source level for 
sound propagating in near-horizontal directions is higher than if the 
array is towed at shallow depths (see Figure 3-5 of L-DEO's 
application). However, the nominal source levels of the array (or the 
estimates of the sound that would be measured from a theoretical point 
source emitting the same total energy as the airgun array) at various 
tow depths are nearly identical. In L-DEO's calculations, a tow depth 
of 9 m is assumed at all times.
    Because the actual source is a distributed source (36 airguns) 
rather than a single point source, the highest sound levels measurable 
at any location in the water will be less than the nominal source (265 
dB re 1 microPam, peak-to-peak). In addition, the effective 
source level for sound propagating in near-horizontal directions will 
be substantially lower than the nominal source level applicable to 
downward propagation because of the directional nature of the sound 
from the airgun array.
Multibeam Echosounder
    The Simrad EM120 operates at 11.25-12.6 kHz and is hull-mounted on 
the Langseth. The beamwidth is 1[deg] fore-aft and 150[deg] 
athwartship. The maximum source level is 242 dB re 1 microPa (rms) 
(Hammerstad, 2005). For deep-water operation, each ``ping'' consists of 
nine successive fan-shaped transmissions, each 15 millisecond (ms) in 
duration and each ensonifying a section that extends 1 fore-aft. The 
nine successive transmissions span an overall cross-track angular 
extent of about 150 , with 16 ms gaps between the pulses for successive 
sectors. A receiver in the overlap area between the 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 seconds (s) at 1,000 m (3,280 ft) to 20 s at 4,000 m 
(13,123 ft) (Kongsberg Maritime, 2005).
Sub-bottom Profiler
    The SBP is normally operated to provide information about the 
sedimentary features and the bottom topography that is simultaneously 
being mapped by the MBES. The energy from the SBP is directed downward 
by a 3.5 kHz transducer in the hull of the Langseth. The output varies 
with water depth from 50 watts in shallow water to 800 watts in deep 
water. The pulse interval is 1 s, but a common mode of operation is to 
broadcast five pulses at 1 s intervals followed by a 5 s pause.

[[Page 78297]]



--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                        Predicted RMS Distances (m)
        Source and Volume              Tow Depth (m)            Water Depth      -----------------------------------------------------------------------
                                                                                          190 dB                  180 dB                  160 dB
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                  ......................  Deep                    12                      40                      385
                                                         -----------------------------------------------------------------------------------------------
Single Bolt airgun                6-9*                    Intermediate            18                      60                      578
                                                         -----------------------------------------------------------------------------------------------
40 in\3\                          ......................  Shallow                 150                     296                     1050
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                  ......................  Deep                    220                     710                     4670
                                                         -----------------------------------------------------------------------------------------------
4 strings                         6-7                     Intermediate            330                     1065                    5189
                                                         -----------------------------------------------------------------------------------------------
36 airguns                        ......................  Shallow                 1600                    2761                    6227
                                 -----------------------------------------------------------------------------------------------------------------------
6600 in\3\                        ......................  Deep                    300                     950                     6000
                                                         -----------------------------------------------------------------------------------------------
                                  8-9                     Intermediate            450                     1425                    6667
                                                         -----------------------------------------------------------------------------------------------
                                  ......................  Shallow                 2182                    3694                    8000
--------------------------------------------------------------------------------------------------------------------------------------------------------
Table 1. Predicted distances to which sound levels >190, 180, and 160 dB re 1 microPa might be received in shallow (<100 m; 328 ft), intermediate (100-
  1,000 m; 328-3,280 ft), and deep (>1,000 m; 3,280 ft) water from the 36 airgun array, as well as a single airgun, used during the Central American
  SubFac and STEEP Gulf of Alaska survey, and planned during the TAIGER SE Asia survey. *The tow depth has minimal effect on the maximum near-field
  output and the shape of the frequency spectrum for the single 40 in3 airgun; thus, the predicted safety radii are essentially the same at each tow
  depth. The most precautionary distances (i.e., for the deepest tow depth, 9m) are shown

    Because the predictions in Table 1 are based in part on empirical 
correction factors derived from acoustic calibration of airgun 
configurations different from those to be used on the Langseth (cf. 
Tolstoy et al., 2004a,b), L-DEO conducted an acoustic calibration study 
of the Langseth's 36-airgun (approximately 6,600 in\3\) array in late 
2007/early 2008 in the Gulf of Mexico (LGL Ltd. 2006). Distances where 
sound levels (e.g., 190, 180, and 160 dB re 1 microPa rms) were 
received in deep, intermediate, and shallow water will be determined 
for various airgun configurations. Acoustic data analysis is ongoing. 
After analysis, the empirical data from the 2007/2008 calibration study 
will be used to refine the exclusion zones (EZ) proposed above for use 
during the TAIGER cruise, if the data are appropriate and available for 
use at the time of the survey.

Proposed Dates, Duration, and Region of Activity

    The survey will encompass the area 17[deg] 30'-26 30' N, 113[deg] 
30'-126 E within the EEZs of Taiwan, China, Japan, and the Philippines. 
The vessel will approach mainland Taiwan within 1 km (0.6 mi) and China 
within 10 km (6.2 mi). The closest approach to the Ryuku Islands will 
be 16 km (9.9 mi). Although the survey will occur at least 32 km (29.9 
mi) from Luzon, Philippines, survey lines will take place approximately 
8 km (5 mi) from some of the Babuyan and Batan islands. Water depths in 
the survey area range from approximately 25 to 6,585 m. The TAIGER 
program consists of 4 legs, each starting and ending in Kao-hsiung, 
Taiwan. The first leg is expected to occur from approximately March 21 
to April 19, 2008 and will include the survey lines in the South China 
Sea. The second leg is scheduled for April 20 to June 7 and will 
include survey lines in Luzon Strait and the Philippine Sea. The third 
leg (approximately June 8-20) will involve OBS recovery by the Langseth 
only; no seismic acquisition will occur during this leg. The fourth 
leg, consisting of the survey lines immediately around Taiwan, is 
scheduled to occur from June 21 to July 14, 2009. The program will 
consist of approximately 103 days of seismic acquisition. The exact 
dates of the activities depend on logistics and weather conditions.

Description of Marine Mammals in the Proposed Activity Area

    A total of 34 cetacean species, including 25 odontocete (dolphins 
and small- and large-toothed whales) species and 9 mysticetes (baleen 
whales) are known to occur in the proposed TAIGER study area (see Table 
2 of L-DEO's application). Cetaceans and pinnipeds are managed by NMFS 
and are the subject of this IHA application. Information on the 
occurrence, distribution, population size, and conservation status for 
each of the 34 marine mammal species that may occur in the proposed 
project area is presented in the Table 2 of L-DEO's application as well 
as here in the table below (Table 2). The status of these species is 
based on the U.S. Endangered Species Act (ESA), the International Union 
for Conservation of Nature (IUCN) Red List of Threatened Species, and 
Convention on International Trade in Endangered Species (CITES). 
Several species are listed as Endangered under the ESA, including the 
Western North Pacific gray, North Pacific right, sperm, humpback, fin, 
sei, and blue whales. In addition, the Indo-Pacific humpback dolphin is 
listed as Near Threatened and the finless porpoise is listed as 
Vulnerable under the 2008 IUCN Red List of Threatened Species (IUCN, 
2008).
    Although the dugong may have inhabited waters off Taiwan, it is no 
longer thought to occur there (March et al., n.d.; Chou, 2004; Perrin 
et al., 2005). Similarly, although the dugong was once widespread 
through the Philippines, current data suggest that it does not inhabit 
the Batan or Babuyan Islands or northwestern Luzon (Marsh et al., n.d.; 
Perrin et al., 2005), where seismic operations will occur. However, the 
dugong does occur off northeastern Luzon (Marsh et al., n.d.; Perrin et 
al., 2005) outside the study area. In China, it is only known to 
inhabit the waters off Guangxi and Guangdong and the west coast of 
Hanain Island (Marsh et al., n.d.; Perrin et al., 2005), which do not 
occur near the study area. It is rare in the Ryuku Islands, but can be 
sighted in Okinawa, particularly off the east coast of the island 
(Yoshida and Trono, 2004; Shirakihara et al., 2007); some individuals 
may have previously occurred in the southern most of the Ryuku Islands, 
Yaeyama (Marsh et al., n.d.), but these animals have not been 
documented there recently (Shirakihara et al., 2007).
    Wang et al. (2001a) noted that during the spring/summer off 
southern Taiwan,

[[Page 78298]]

the highest number of marine mammal sightings and species occur during 
April and June. The number of sightings per survey effort and the 
number of species were highest directly west of the southern tip of 
Taiwan and northeast off the southern tip.
    Table 2 below outlines the cetacean species, their habitat and 
abundance in the proposed project area, and the requested take levels. 
Additional information regarding the distribution of these species 
expected to be found in the project area and how the estimated 
densities were calculated may be found in L-DEO's application.

  Table 2. The occurrence, habitat, regional abundance, conservation status, best and maximum density estimates, number of marine mammals that could be
   exposed to sound level at or above 160dB re 1microPa, best estimate of number of individuals exposed, and best estimate of number of exposures per
             marine mammal in or near the proposed seismic survey area in SE Asia. See Tables 2-4 in L-DEO's application for further detail.
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                  Occurrence in Study                        Regional Population                          Density/          Density/
            Species                 Area in SE Asia           Habitat                Size                ESA\a\       1000km\b\ (best)   1000km\c\ (max)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Mysticetes
-------------------------------
Western North Pacific gray      Rare                     Coastal           131\d\                   EN                0                 0
 whale
(Eschrichtius robustus)
--------------------------------------------------------------------------------------------------------------------------------------------------------
North Pacific right whale       Rare                     Pelagic and       Less than 100\e\         EN                0                 0
(Eubalaena japonica)                                      coastal
--------------------------------------------------------------------------------------------------------------------------------------------------------
Humpback whale                  Uncommon                 Mainly nearshore  938-1107\f\              EN                0.89              1.33
(Megaptera novaeangliae)                                  waters and
                                                          banks
--------------------------------------------------------------------------------------------------------------------------------------------------------
Minke whale                     Uncommon                 Pelagic and       25,000\g\                NL                0.03              0.04
(Balaenoptera acutorostrata)                              coastal
--------------------------------------------------------------------------------------------------------------------------------------------------------
Bryde's whale                   Common                   Pelagic and       20,000-30,000\e,h\       NL                0.27              0.41
(Balaenoptera brydei)                                     coastal
--------------------------------------------------------------------------------------------------------------------------------------------------------
Omura's whale                   Uncommon                 Pelagic and       N.A.                     NL                0.03              0.04
(Balaenoptera omurai)                                     coastal
--------------------------------------------------------------------------------------------------------------------------------------------------------
Sei whale                       Uncommon                 Primarily         7,260-12,620\i\          EN                0.03              0.04
(Balaenoptera borealis)                                   offshore,
                                                          pelagic
--------------------------------------------------------------------------------------------------------------------------------------------------------
Fin whale                       Uncommon                 Continental       13.620-18.680\j\         EN                0.03              0.04
(Balaenoptera physalus)                                   slope, mostly
                                                          pelagic
--------------------------------------------------------------------------------------------------------------------------------------------------------
Blue whale                      Uncommon                 Pelagic and       N.A.                     EN                0.03              0.04
(Balaenoptera musculus)                                   coastal
--------------------------------------------------------------------------------------------------------------------------------------------------------
Odontocetes
-------------------------------
Sperm whale                     Uncommon                 Usually pelagic   26,674\k\                NL                0.03              0.04
(Physeter macrocephalus)                                  and deep seas
--------------------------------------------------------------------------------------------------------------------------------------------------------
Pygmy sperm whale               Uncommon                 Deep waters off   N.A.                     NL                0                 0
(Kogia breviceps)                                         shelf
--------------------------------------------------------------------------------------------------------------------------------------------------------
Dwarf sperm whale               Common?                  Deep waters off   11,200\e\                NL                4.25              6.68
(Kogia sima)                                              the shelf
--------------------------------------------------------------------------------------------------------------------------------------------------------
(Kogia sp.)                     Common?                  Deep waters off   N.A.                     NL                0.26              0.40
                                                          the shelf
--------------------------------------------------------------------------------------------------------------------------------------------------------
Cuvier's beaked whale           Likely Common            Pelagic           20,000\e\                NL                0.34              0.75
(Ziphius cavirostris)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Longman's beaked whale          Rare                     Deep water        N.A.                     NL                N.A.              N.A.
(Indopacetus pacificus)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Blainville's beaked whale       Uncommon?                Pelagic           25,300\l\                NL                0.89              1.60
(Mesoplodon densirostris)
--------------------------------------------------------------------------------------------------------------------------------------------------------

[[Page 78299]]

 
Ginkgo-toothed beaked whale     Rare                     Pelagic           N.A.                     NL                N.A.              N.A.
(Mesoplodon ginkgodens)
--------------------------------------------------------------------------------------------------------------------------------------------------------
(Mesoplodon sp.)                Uncommon?                Pelagic           N.A.                     NL                1.55              1.60
--------------------------------------------------------------------------------------------------------------------------------------------------------
Unidentified beaked whale       Rare                     Pelagic           N.A.                     NL                0.72              0.94
--------------------------------------------------------------------------------------------------------------------------------------------------------
Rough-toothed beaked dolphin    Common                   Deep water        146,000 ETP\e\           NL                1.33              5.44
(Steno bredanensis)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Indo-Pacific humpback dolphin   Uncommon                 Coastal           1,680 China + Taiwan\e\  NL                24.30             35.36
(Sousa chinensis)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Common bottlenose dolphin       Common                   Coastal and       243,500 ETP\e\           NL                24.30             35.36
(Tursiops truncatus)                                      oceanic, shelf
                                                          break
--------------------------------------------------------------------------------------------------------------------------------------------------------
Indo-Pacific bottlenose         Common?                  Coastal and       N.A.                     NL                43.60             65.40
 dolphin                                                  shelf waters
(Tursiops aduncus)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Pacific white-sided dolphin     Rare                     Coastal and       930,000-990,000\e\       NL                N.A.              N.A.
(Lagenorhynchus obliquidens)                              pelagic
--------------------------------------------------------------------------------------------------------------------------------------------------------
Pantropical spotted dolphin     Common                   Coastal and       800,000 ETP\e\           NL                120.80            140.97
(Stenella attenuata)                                      pelagic
--------------------------------------------------------------------------------------------------------------------------------------------------------
Spinner dolphin                 Common                   Coastal and       800,000 ETP\e\           NL                54.84             88.89
(Stenella longirostris)                                   pelagic
--------------------------------------------------------------------------------------------------------------------------------------------------------
Striped dolphin                 Common                   Coastal and       1,000,000 ETP\e\         NL                0.20              0.32
(Stenella coeruleoalba)                                   pelagic
--------------------------------------------------------------------------------------------------------------------------------------------------------
Fraser's dolphin                Common                   Waters greater    289,000 ETP\e\           NL                96.84             124.14
(Lagenodelphis hosei)                                     than 1,000 m
--------------------------------------------------------------------------------------------------------------------------------------------------------
Short-beaked common dolphin     Rare                     Shelf and         3,000,000 ETP\e\         NL                N.A.              N.A.
(Delphinus delphis)                                       pelagic,
                                                          seamounts
--------------------------------------------------------------------------------------------------------------------------------------------------------
Long-beaked common dolphin      Uncommon                 Coastal           N.A.                     NL                0.05              0.12
(Delphinus capensis)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Risso's dolphin                 Common                   Pelagic           175,000 ETP\e\           NL                41.88             67.18
(Grampus griseus)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Melon-headed whale              Common?                  Oceanic           45,000 ETP\e\            NL                13.37             20.86
(Peponocephala electra)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Pygmy killer whale              Uncommon                 Deep,             39,000 ETP\e\            NL                2.01              3.16
(Feresa attenuata)                                        pantropical
                                                          waters
--------------------------------------------------------------------------------------------------------------------------------------------------------
False killer whale              Common?                  Pelagic           40,000\n\                NL                4.56              4.77
(Pseudorca crassidens)
--------------------------------------------------------------------------------------------------------------------------------------------------------

[[Page 78300]]

 
Killer whale                    Uncommon?                Widely            8,500 ETP\e\             NL                1.00              1.73
(Orcinus orca)                                            distributeds
--------------------------------------------------------------------------------------------------------------------------------------------------------
Short-finned pilot whale        Common?                  Mostly pelagic,   500,000 ETP\e\           NL                3.83              6.43
(Globicephala macrorhynchus)                              relief
                                                          topography
--------------------------------------------------------------------------------------------------------------------------------------------------------
Finless porpoise                Common?                  Coastal           5,220-10,220             NL                4.36              6.54
(Neophocaena phocaenoides)                                                 Japan + HK\e\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Sirenians
-------------------------------
Dugong                          Uncommon?                Coastal           N.A.                     EN                N.A.              N.A.
(Dugong dugon)
--------------------------------------------------------------------------------------------------------------------------------------------------------
N.A. - Data not available or species status was not assessed, ETP - Eastern Tropical Pacific, HK = Hong Kong
\a\ U.S. Endangered Species Act: EN = Endangered, T = Threatened, NL = Not listed
\b\ Best estimate as listed in Table 3 of the application.
\c\ Maximum estimate as listed in Table 3 of the application.
\d\ Vladimirov et al. (2008)
\e\ North Pacific unless otherwise indicated (Jefferson et al., 2008)
\f\ Western North Pacific (Calambokidis et al., 2008)
\g\ Northwest Pacific and Okhotsk Sea (IWC, 2007a)
\h\ Kitakado et al. (2008)
\i\ Tillman (1977)
\j\ Ohsumi and Wada (1974)
\k\ Western North Pacific (Whitehead, 2002b)
\l\ ETP; all Mesoplodon spp. (Wade and Gerrodette, 1993)
\m\ IUCN states that this species should be re-assessed following taxonomic classification of the two forms. The chinensis-type would be considered
  vulnerable (IUCN, 2008)
\n\ ETP (Wade and Gerrodette, 1993)

Potential Effects on Marine Mammals

Potential Effects of Airguns

    The sounds from airguns might result in one or more of the 
following: tolerance, masking of natural sounds, behavioral 
disturbances, temporary or permanent hearing impairment, and non-
auditory physical or physiological effects (Richardson et al., 1995; 
Gordon et al., 2004; Nowacek et al., 2007; Southall et al., 2007). 
Permanent hearing impairment, in the unlikely event that it occurred, 
would constitute injury, but temporary threshold shift (TTS) is not an 
injury (Southall et al., 2007). With the possible exception of some 
cases of temporary threshold shift in harbor seals, it is unlikely that 
the project would result in any cases of temporary or especially 
permanent hearing impairment, or any significant non-auditory physical 
or physiological effects. Some behavioral disturbance is expected, but 
this would be localized and short-term.
    The root mean square (rms) received levels that are used as impact 
criteria for marine mammals are not directly comparable to the peak or 
peak-to-peak values normally used to characterize source levels of 
airgun arrays. The measurement units used to describe airgun sources, 
peak or peak-to-peak decibels, are always higher than the rms decibels 
referred to in biological literature. A measured received level of 160 
dB rms in the far field would typically correspond to a peak 
measurement of approximately 170 to 172 dB, and to a peak-to-peak 
measurement of approximately 176 to 178 dB, as measured for the same 
pulse received at the same location (Greene, 1997; McCauley et al., 
1998, 2000a). The precise difference between rms and peak or peak-to-
peak values depends on the frequency content and duration of the pulse, 
among other factors. However, the rms level is always lower than the 
peak or peak-to-peak level for an airgun-type source.
Tolerance
    Numerous studies have shown that pulsed sounds from airguns are 
often readily detectable in the water at distances of many kilometers. 
For a summary of the characteristics of airgun pulses, see Appendix B 
(3) of L-DEO's application. Numerous studies have shown that marine 
mammals at distances more than a few kilometers from operating seismic 
vessels often show no apparent response-see Appendix B (5) of L-DEO's 
application. That is often true even in cases when the pulsed sounds 
must be readily audible to the animals based on measured received 
levels and the hearing sensitivity of the mammal group. Although 
various baleen whales, toothed whales, and (less frequently) pinnipeds 
have been shown to react behaviorally to airgun pulses under some 
conditions, at other times, mammals of all three types have shown no 
overt reactions. In general, pinnipeds usually seem to be more tolerant 
of exposure to airgun pulses than are cetaceans, with relative 
responsiveness of baleen and toothed whales being variable.
Masking
    Obscuring of sounds of interest by interfering sounds, generally at 
similar frequencies, is known as masking. Masking effects of pulsed 
sounds (even from large arrays of airguns) on marine

[[Page 78301]]

mammal calls and other natural sounds are expected to be limited, 
although there are few specific data of relevance. Because of the 
intermittent nature and low duty cycle of seismic pulses, animals can 
emit and receive sounds in the relatively quiet intervals between 
pulses. However in exceptional situations, reverberation occurs for 
much or all of the interval between pulses (Simard et al., 2005; Clark 
and Gagnon, 2006). Some baleen and toothed whales are known to continue 
calling in the presence of seismic pulses. The airgun sounds are 
pulsed, with quiet periods between the pulses, and whale calls often 
can be heard between the seismic pulses (Richardson et al., 1986; 
McDonald et al., 1995; Greene et al., 1999; Nieukirk et al., 2004; 
Smultea et al., 2004; Holst et al., 2005a,b, 2006). In the northeast 
Pacific Ocean, blue whale calls have been recorded during a seismic 
survey off Oregon (McDonald et al., 1995). Among odontocetes, there has 
been one report that sperm whales cease calling when exposed to pulses 
from a very distant seismic ship (Bowles et al., 1994), a more recent 
study reports that sperm whales off northern Norway continued calling 
in the presence of seismic pulses (Madsen et al., 2002). That has also 
been shown during recent work in the Gulf of Mexico and Caribbean Sea 
(Smultea et al., 2004; Tyack et al., 2006). Masking effects of seismic 
pulses are expected to be negligible in the case of the small 
odontocetes given the intermittent nature of seismic pulses. Dolphins 
and porpoises commonly are heard calling while airguns are operating 
(Gordon et al., 2004; Smultea et al., 2004; Holst et al., 2005a,b; 
Potter et al., 2007). Also, the sounds important to small odontocetes 
are predominantly at much higher frequencies than the airgun sounds, 
thus further limiting the potential for masking. In general, masking 
effects of seismic pulses are expected to be minor, given the normally 
intermittent nature of seismic pulses. Masking effects on marine 
mammals are discussed further in Appendix B (4) of L-DEO's application.
Disturbance Reactions
    Disturbance includes a variety of effects, including subtle changes 
in behavior, more conspicuous changes in activities, and displacement. 
Reactions to sound, if any, depend on species, state of maturity, 
experience, current activity, reproductive state, time of day, and many 
other factors. If a marine mammal responds to an underwater sound by 
changing its behavior or moving a small distance, the response may or 
may not rise to the level of ``harassment,'' or affect the stock or the 
species as a whole. However, if a sound source displaces marine mammals 
from an important feeding or breeding area for a prolonged period, 
impacts on animals or on the stock or species could potentially be 
significant. Given the many uncertainties in predicting the quantity 
and types of impacts of noise on marine mammals, it is common practice 
to estimate how many mammals are likely to be present within a 
particular distance of industrial activities, or exposed to a 
particular level of industrial sound. This practice potentially 
overestimates the numbers of marine mammals that are affected in some 
biologically-important manner.
    The sound exposure thresholds that affect marine mammals 
behaviorally are based on behavioral observations during studies of 
several species. However, information is lacking for many species. 
Detailed studies have been done on humpback, gray, bowhead, and sperm 
whales and on ringed seals. Less detailed data are available for some 
other species of baleen whales, small toothed whales, and sea otters, 
but for many species there are no data on responses to marine seismic 
surveys.
    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 
application, baleen whales exposed to strong noise pulses from airguns 
often react by deviating from their normal migration route and/or 
interrupting their feeding activities and moving away from the sound 
source. In the case of the migrating gray and bowhead whales, the 
observed changes in behavior appeared to be of little or no biological 
consequence to the animals. They simply avoided the sound source by 
displacing their migration route to varying degrees, but within the 
natural boundaries of the migration corridors.
    Studies of gray, bowhead, and humpback whales have demonstrated 
that received levels of pulses in the 160-170 dB re 1 microPa rms range 
seem to cause obvious avoidance behavior in a substantial fraction of 
the animals exposed. In many areas, seismic pulses from large arrays of 
airguns diminish to those levels at distances ranging from 4-15 km 
(2.8-9 mi) from the source. A substantial proportion of the baleen 
whales within those distances may show avoidance or other strong 
disturbance reactions to the airgun array. Subtle behavioral changes 
sometimes become evident at somewhat lower received levels, and studies 
summarized in Appendix B(5) of L-DEO's application have shown that some 
species of baleen whales, notably bowhead and humpback whales, at times 
show strong avoidance at received levels lower than 160-170 dB re 1 
microPa (rms).
    Responses of humpback whales to seismic surveys have been studied 
during migration, on the summer feeding grounds, and on Angolan winter 
breeding grounds; there has also been discussion of effects on the 
Brazilian wintering grounds. McCauley et al. (1998, 2000a) studied the 
responses of humpback whales off Western Australia to a full-scale 
seismic survey with a 16-airgun, 2,678-in\3\ array, and to a single 20-
in\3\ airgun with a source level of 227 dB re 1 microPa m peak-to-peak. 
McCauley et al. (1998) documented that initial avoidance reactions 
began at 5-8 km (3.1-5 mi) from the array, and that those reactions 
kept most pods approximately 3-4 km (1.9-2.5 mi) from the operating 
seismic boat. McCauley et al. (2000) noted localized displacement 
during migration of 4-5 km (2.5-3.1 mi) by traveling pods and 7-12 km 
(4.3-7.5 mi) by cow-calf pairs. Avoidance distances with respect to the 
single airgun were smaller (2 km (1.2 mi)) but consistent with the 
results from the full array in terms of received sound levels. The mean 
avoidance distance from the airgun corresponded to a received sound 
level of 140 dB re 1 microPa (rms); that was the level at which 
humpbacks started to show avoidance reactions to an approaching airgun. 
The standoff range, i.e., the closest point of approach of the whales 
to the airgun, corresponded to a received level of 143 dB re 1 microPa 
(rms). The initial avoidance response generally occurred at distances 
of 5-8 km (3.1-5 mi) from the airgun array and 2 km (1.2 mi) from the 
single airgun. However, some individual humpback whales, especially 
males, approached within distances of 100-400 m (328-1,312 ft), where 
the maximum received level was 179 dB re 1 microPa (rms).
    Humpback whales on their summer feeding grounds in southeast Alaska 
did not exhibit persistent avoidance when exposed to seismic pulses 
from a 1.64-L (100 in\3\) airgun (Malme et al., 1985). Some humpbacks 
seemed ``startled'' at received levels of 150-169 dB re 1 ?Pa on an 
approximate rms basis. Malme et al. (1985) concluded that there was no 
clear evidence of avoidance, despite the possibility of subtle effects, 
at received

[[Page 78302]]

levels up to 172 re 1 microPa on an approximate rms basis.
    It has been suggested that South Atlantic humpback whales wintering 
off Brazil may be displaced or even strand upon exposure to seismic 
surveys (Engel et al., 2004). The evidence for this was circumstantial 
and subject to alternative explanations (IAGC, 2004). Also, the 
evidence was not consistent with subsequent results from the same area 
of Brazil (Parente et al., 2006), or with results from direct studies 
of 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 the activity 
(migrating vs. feeding). Bowhead whales migrating west across the 
Alaskan Beaufort Sea in autumn, in particular, are unusually 
responsive, with substantial avoidance occurring out to distances of 
20-30 km (12.4-18.6 mi) from a medium-sized airgun source at received 
sound levels of around 120-130 dB re 1 microPa (rms) (Miller et al., 
1999; Richardson et al., 1999; see Appendix B (5) of L-DEO's 
application). However, more recent research on bowhead whales (Miller 
et al., 2005a; 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 a received level of 
about 160-170 dB re 1 microPa (rms) (Richardson et al., 1986; Ljungblad 
et al., 1988; Miller et al., 2005a).
    Reactions of migrating and feeding (but not wintering) gray whales 
to seismic surveys have been studied. Malme et al. (1986, 1988) studied 
the responses of feeding Eastern Pacific gray whales to pulses from a 
single 100 in\3\ airgun off St. Lawrence Island in the northern Bering 
Sea. Malme et al. (1986, 1988) estimated, based on small sample sizes, 
that 50 percent of feeding gray whales ceased feeding at an average 
received pressure level of 173 dB re 1 microPa on an (approximate) rms 
basis, and that 10 percent of feeding whales interrupted feeding at 
received levels of 163 dB. Those findings were generally consistent 
with the results of experiments conducted on larger numbers of gray 
whales that were migrating along the California coast (Malme et al., 
1984; Malme and Miles, 1985), and with observations of Western Pacific 
gray whales feeding off Sakhalin Island, Russia, when a seismic survey 
was underway just offshore of their feeding area (Gailey et al., 2007; 
Johnson et al., 2007; Yazvenko et al. 2007a,b), along with data on gray 
whales off British Columbia (Bain and Williams, 2006).
    Various species of Balaenoptera (blue, sei, fin, Bryde's, and minke 
whales) have occasionally been reported in areas ensonified by airgun 
pulses (Stone, 2003; MacLean and Haley, 2004; Stone and Tasker, 2006). 
Sightings by observers on seismic vessels off the United Kingdom from 
1997 to 2000 suggest that, at times of good sightability, sighting 
rates for mysticetes (mainly fin and sei whales) were similar when 
large arrays of airguns were shooting and not shooting (Stone, 2003; 
Stone and Tasker, 2006). However, these whales tended to exhibit 
localized avoidance, remaining significantly (on average) from the 
airgun array during seismic operations compared with non-seismic 
periods (Stone and Tasker, 2006). In a study off Nova Scotia, Moulton 
and Miller (2005) found little difference in sighting rates (after 
accounting for water depth) and initial sighting distances of 
balaenopterid whales when airguns were operating vs. silent. However, 
there were indications that these whales were more likely to be moving 
away when seen during airgun operations. Similarly, ship-based 
monitoring studies of blue, fin, sei, and minke whales offshore of 
Newfoundland (Orphan Basin and Laurentian Sub-basin) found no more than 
small differences in sighting rates and swim direction during seismic 
vs. non-seismic periods (Moulton et al., 2005, 2006a,b).
    Data on short-term reactions (or lack of reactions) of cetaceans to 
impulsive noises do not necessarily provide information about long-term 
effects. It is not known whether impulsive noises affect reproductive 
rate or distribution and habitat use in subsequent days or years. 
However, gray whales continued to migrate annually along the west coast 
of North America with substantial increases in the population over 
recent years, despite intermittent seismic exploration and much ship 
traffic in that area for decades (see Appendix A in Malme et al., 1984; 
Richardson et al., 1995; Angliss and Outlaw, 2008). The Western Pacific 
gray whale population did not seem affected by a seismic survey in its 
feeding ground during a prior year (Johnson et al., 2007). Bowhead 
whales continued to travel to the eastern Beaufort Sea each summer, and 
their numbers have increased notably, despite seismic exploration in 
their summer and autumn range for many years (Richardson et al., 1987). 
In any event, brief exposures to sound pulses from the proposed airgun 
source are highly unlikely to result in prolonged effects.
    Toothed Whales - Little systematic information is available about 
reactions of toothed whales to noise pulses. Few studies similar to the 
more extensive baleen whale/seismic pulse work summarized above have 
been reported for toothed whales. However, systematic studies on sperm 
whales have been done (Jochens and Biggs, 2003; Tyack et al., 2003; 
Jochens et al., 2006; Miller et al., 2006), and there is an increasing 
amount of information about responses of various odontocetes to seismic 
surveys based on monitoring studies (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 sometimes see 
dolphins and other small toothed whales near operating airgun arrays, 
but in general there seems to be a tendency for most delphinids to show 
some avoidance of operating seismic vessels (Goold, 1996a,b,c; 
Calambokidis and Osmek, 1998; Stone, 2003; Moulton and Miller, 2005; 
Holst et al., 2006; Stone and Tasker, 2006; Weir, 2008). However, some 
dolphins seem to be attracted to the seismic vessel and floats, and 
some ride the bow wave of the seismic vessel even when large airgun 
arrays are firing (Moulton and Miller, 2005). Nonetheless, there have 
been indications that small toothed whales sometimes tend to head away 
or to maintain a somewhat greater distance from the vessel, when a 
large array of airguns is operating than when it is silent (Stone and 
Tasker, 2006; Weir, 2008). In most cases, the avoidance radii for 
delphinids appear to be small, on the order of 1 km (0.62 mi) or less, 
and some individuals show no apparent avoidance. The beluga is a 
species that (at least at times) shows long-distance avoidance of 
seismic vessels. Aerial surveys during seismic operations in the 
southeastern Beaufort Sea during summer recorded much lower sighting 
rates of beluga whales within 10-20 km (6.2-12.4 mi) compared with 20-
30 km (mi) from an operating airgun array, and observers on seismic 
boats in that area rarely see belugas (Miller et al., 2005; Harris et 
al., 2007).

[[Page 78303]]

    Captive bottlenose dolphins and beluga whales exhibited changes in 
behavior when exposed to strong pulsed sounds similar in duration to 
those typically used in seismic surveys (Finneran et al., 2000, 2002, 
2005; Finneran and Schlundt, 2004). The animals tolerated high received 
levels of sound (pk-pk level >200 dB re 1 microPa) before exhibiting 
aversive behaviors. For pooled data at 3, 10, and 20 kHz, sound 
exposure levels during sessions with 25, 50, and 75 percent altered 
behavior were 180, 190, and 199 dB re 1 microPa\2\, respectively 
(Finneran and Schlundt, 2004).
    Results for porpoises depend on species. Dall's porpoises seem 
relatively tolerant of airgun operations (MacLean and Koski, 2005) and, 
during a survey with a large airgun array, tolerated higher noise 
levels than did harbor porpoises and gray whales (Bain and Williams, 
2006). However, Dall's porpoises do respond to the approach of large 
airgun arrays by moving away (Calambokidis and Osmek, 1998; Bain and 
Williams, 2006). The limited available data suggest that harbor 
porpoises show stronger avoidance (Stone, 2003; Bain and Williams, 
2006; Stone and Tasker, 2006). This apparent difference in 
responsiveness of these two porpoise species is consistent with their 
relative responsiveness to boat traffic and some other acoustic sources 
in general (Richardson et al., 1995; Southall et al. 2007).
    Most studies of sperm whales exposed to airgun sounds indicate that 
this species shows considerable tolerance of airgun pulses (Stone, 
2003; Moulton et al., 2005, 2006a; Stone and Tasker, 2006; Weir, 2008). 
In most cases, the whales do not show strong avoidance and continue to 
call (see Appendix B in L-DEO's EA). However, controlled exposure 
experiments in the Gulf of Mexico indicate that foraging effort is 
somewhat altered upon exposure to airgun sounds (Jochens et al., 2006).
    There are almost no specific data on the behavioral reactions of 
beaked whales to seismic surveys. However, northern bottlenose whales 
(Hyperodon ampullatus) continued to produce high-frequency clicks when 
exposed to sound pulses from distant seismic surveys (Laurinolli and 
Cochrane, 2005; Simard et al., 2005). Most beaked whales tend to avoid 
approaching vessels of other types (Wursig et al., 1998). They may also 
dive for an extended period when approached by a vessel (Kasuya, 1986). 
It is likely that these beaked whales would normally show strong 
avoidance of an approaching seismic vessel, but this has not been 
documented explicitly.
    Odontocete reactions to large arrays of airguns are variable and, 
at least for delphinids and Dall's porpoises, seem to be confined to a 
smaller radius than has been observed for the more responsive of the 
mysticetes, belugas, and harbor porpoises (Appendix B of L-DEO's EA).
    Additional details on the behavioral reactions (or the lack 
thereof) by all types of marine mammals to seismic vessels can be found 
in Appendix B of L-DEO's application.
Hearing Impairment and Other Physical Effects
    Temporary or permanent hearing impairment is a possibility when 
marine mammals are exposed to very strong sounds, but there has been no 
specific documentation of this for marine mammals exposed to sequences 
of airgun pulses.
    NMFS will be developing new noise exposure criteria for marine 
mammals that take account of the now-available scientific data on 
temporary threshold shift (TTS), the expected offset between the TTS 
and permanent threshold shift (PTS) thresholds, differences in the 
acoustic frequencies to which different marine mammal groups are 
sensitive, and other relevant factors. Detailed recommendations for new 
science-based noise exposure criteria were published in early 2008 
(Southall et al., 2007).
    Several aspects of the planned monitoring and mitigation measures 
for this project (see below) are designed to detect marine mammals 
occurring near the airguns to avoid exposing them to sound pulses that 
might, at least in theory, cause hearing impairment. In addition, many 
cetaceans and (to a limited degree) pinnipeds are likely to show some 
avoidance of the area with high received levels of airgun sound (see 
above). In those cases, the avoidance responses of the animals 
themselves will reduce or (most likely) avoid any possibility of 
hearing impairment.
    Non-auditory physical effects may also occur in marine mammals 
exposed to strong underwater pulsed sound. Possible types of non-
auditory physiological effects or injuries that theoretically might 
occur in mammals close to a strong sound source include stress, 
neurological effects, bubble formation, resonance effects, and other 
types of organ or tissue damage. It is possible that some marine mammal 
species (i.e., beaked whales) may be especially susceptible to injury 
and/or stranding when exposed to strong pulsed sounds. However, as 
discussed below, there is no definitive evidence that any of these 
effects occur even for marine mammals in close proximity to large 
arrays of airguns. It is especially unlikely that any effects of these 
types would occur during the present project given the brief duration 
of exposure of any given mammal and the proposed 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 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. At least 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 level of a single seismic pulse (with no 
frequency weighting) might need to be approximately 186 dB re 1 
microPa\2\s (i.e., 186 dB SEL or approximately 221-226 dB pk-
pk) in order to produce brief, mild TTS. Exposure to several strong 
seismic pulses that each have received levels near 175-180 dB SEL might 
result in slight TTS in a small odontocete, assuming the TTS threshold 
is (to a first approximation) a function of the total received pulse 
energy. The distance from the Langseth's airguns at which the received 
energy level (per pulse) would be expected to be [gteqt]175-180 dB SEL 
are the distances shown in the 190 dB re 1 microPa (rms) column in 
Table 3 of L-DEO's application and Table 1 above (given that the rms 
level is approximately 10-15 dB higher than the SEL value for the same 
pulse). Seismic pulses with received energy levels [gteqt]175-180 dB 
SEL (190 dB re 1 microPa (rms)) are expected to be restricted to radii 
no more than 140-200 m (459-656 ft) around the airguns. The specific 
radius depends on the number of airguns, the depth of the water, and 
the tow depth of the airgun array. For an odontocete closer to the 
surface, the maximum radius with

[[Page 78304]]

[gteqt]175-180 dB SEL or [gteqt]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 not published TTS 
information for other species of cetaceans. However, preliminary 
evidence from 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 required to induce TTS. The frequencies to which 
baleen whales are most sensitive are lower than those for odontocetes, 
and natural background noise levels at those low frequencies tend to be 
higher. As a result, auditory thresholds of baleen whales within their 
frequency band of best hearing are believed to be higher (less 
sensitive) than are those of odontocetes at their best frequencies 
(Clark and Ellison, 2004). From this, it is suspected that received 
levels causing TTS onset may also be higher in baleen whales. In any 
event, no cases of TTS are expected given three considerations: (1) the 
relatively low abundance of baleen whales expected in the planned study 
areas; (2) the strong likelihood that baleen whales would avoid the 
approaching airguns (or vessel) before being exposed to levels high 
enough for there to be any possibility of TTS; and (3) the mitigation 
measures that are planned.
    In pinnipeds, TTS thresholds associated with exposure to brief 
pulses (single or multiple) of underwater sound have not been measured. 
Initial evidence from prolonged (non-pulse) exposures suggested that 
some pinnipeds may incur TTS at somewhat lower received levels than do 
small odontocetes exposed for similar durations (Kastak et al., 1999, 
2005; Ketten et al., 2001; Au et al., 2000). The TTS threshold for 
pulsed sounds has been indirectly estimated as being an SEL of 
approximately 171 dB re 1 microPa\2\s (Southall et al., 2007), 
which would be equivalent to a single pulse with received level 
approximately 181-186 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 are likely to be 
higher (Kastak et al., 2005).
    A marine mammal within a radius of less than 100 m (328 ft) around 
a typical large array of operating airguns might be exposed to a few 
seismic pulses with levels of greater than or equal to 205 dB, and 
possibly more pulses if the mammal moved with the seismic vessel. (As 
noted above, most cetacean species tend to avoid operating airguns, 
although not all individuals do so.) In addition, ramping up airgun 
arrays, which is standard operational protocol for large airgun arrays, 
should allow cetaceans to move away form the seismic source and to 
avoid being exposed to the full acoustic output of the airgun array. 
Even with a large airgun array, it is unlikely that the cetaceans would 
be exposed to airgun pulses at a sufficiently high level for a 
sufficiently long period to cause more than mild TTS, given the 
relative movement of the vessel and the marine mammal. The potential 
for TTS is much lower in this project. With a large array of airguns, 
TTS would be most likely in any odontocetes that bow-ride or otherwise 
linger near the airguns. While bow-riding, odontocetes would be at or 
above the surface, and thus not exposed to strong pulses given the 
pressure-release effect at the surface. However, bow-riding animals 
generally dive below the surface intermittently. If they did so while 
bow-riding near airguns, they would be exposed to strong sound pulses, 
possibly repeatedly. If some cetaceans did incur TTS through exposure 
to airgun sounds, this would very likely be mild, temporary, and 
reversible.
    To avoid the potential for injury, NMFS has determined that 
cetaceans and pinnipeds should not be exposed to pulsed underwater 
noise at received levels exceeding, respectively, 180 and 190 dB re 1 
microPa (rms). As summarized above, data that are now available imply 
that TTS is unlikely to occur unless odontocetes (and probably 
mysticetes as well) are exposed to airgun pulses stronger than 180 dB 
re 1 microPa (rms).
    Permanent Threshold Shift - When PTS occurs, there is physical 
damage to the sound receptors in the ear. In some cases, there can be 
total or partial deafness, while in other cases, the animal has an 
impaired ability to hear sounds in specific frequency ranges.
    There is no specific evidence that exposure to pulses of airgun 
sound can cause PTS in any marine mammal, even with large arrays of 
airguns. However, given the possibility that mammals close to an airgun 
array might incur TTS, there has been further speculation about the 
possibility that some individuals occurring very close to airguns might 
incur PTS. Single or occasional occurrences of mild TTS are not 
indicative of permanent auditory damage in terrestrial mammals. 
Relationships between TTS and PTS thresholds have not been studied in 
marine mammals, but are assumed to be similar to those in humans and 
other terrestrial mammals. PTS might occur at a received sound level at 
least several decibels above that inducing mild TTS if the animal were 
exposed to strong sound pulses with rapid rise time (see Appendix B (6) 
of L-DEO's application). The specific difference between the PTS and 
TTS thresholds has not been measured for marine mammals exposed to any 
sound type. However, based on data from terrestrial mammals, a 
precautionary assumption is that the PTS threshold for impulse sounds 
(such as airgun pulses as received close to the source) is at least 6 
dB higher than the TTS threshold on a peak-pressure basis.
    On an SEL basis, Southall et al. (2007) estimated that received 
levels would need to exceed the TTS threshold by at least 15 dB for 
there to be risk of PTS. Thus, for cetaceans they estimate that the PTS 
threshold might be a cumulative SEL (for the sequence of received 
pulses) of approximately 198 dB re 1 microPa\2\s. Additional 
assumptions had to be made to derive a corresponding estimate for 
pinnipeds. Southall et al. (2007) estimate that the PTS threshold could 
be a cumulative SEL of approximately 186 dB 1 microPa\2\.s in the 
harbor seal; for the California sea lion and northern elephant seal the 
PTS threshold would probably be higher. Southall et al. (2007) also 
note that, regardless of the SEL, there is concern about the 
possibility of PTS if a cetacean or pinniped receives one or more 
pulses with peak pressure exceeding 230 or 218 dB re 1 microPa (3.2 
bar.m, 0-pk), which would only be found within a few meters of the 
largest (360-in\3\) airguns 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 near-field 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 could occur. In fact, 
even the levels immediately adjacent to the airguns may not be 
sufficient to induce PTS, especially because a mammal would not be 
exposed to more than one strong pulse unless it swam immediately 
alongside the airgun for a period longer than the inter-pulse interval. 
Baleen whales generally avoid the immediate area around operating 
seismic vessels, as do some other marine mammals. The planned 
monitoring and mitigation measures, including visual monitoring, 
passive acoustic monitoring (PAM), power downs, and shut downs of the 
airguns when mammals are seen within the EZ will minimize the already 
minimal probability of exposure of marine

[[Page 78305]]

mammals to sounds strong enough to induce PTS.
    Non-auditory Physiological Effects - Non-auditory physiological 
effects or injuries that theoretically might occur in marine mammals 
exposed to strong underwater sound include stress, neurological 
effects, bubble formation, resonance effects, and other types of organ 
or tissue damage (Cox et al., 2006; Southall et al., 2007). However, 
studies examining such effects are limited. If any such effects do 
occur, they would probably be limited to unusual situations when 
animals might be exposed at close range for unusually long periods, 
when sound is strongly channeled with less-than-normal propagation 
loss, or when dispersal of the animals is constrained by shorelines, 
shallows, etc. Airgun pulses, because of their brevity and 
intermittence, are less likely to trigger resonance or bubble formation 
than are more prolonged sounds. It is doubtful that any single marine 
mammal would be exposed to strong seismic sounds for time periods long 
enough to induce physiological stress.
    Until recently, it was assumed that diving marine mammals are not 
subject to the bends or air embolism. This possibility was first 
explored at a workshop (Gentry [ed.], 2002) held to discuss whether a 
stranding of beaked whales in the Bahamas in 2000 (Balcomb and 
Claridge, 2001; NOAA and USN, 2001) might have been related to bubble 
formation in tissues caused by exposure to noise from naval sonar. 
However, this link could not be confirmed. Jepson et al. (2003) first 
suggested a possible link between mid-frequency sonar activity and 
acute chronic tissue damage that results from the formation in vivo of 
gas bubbles, based on a beaked whale stranding in the Canary Islands in 
2002 during naval exercises. Fernandez et al. (2005a) showed those 
beaked whales did indeed have gas bubble-associated lesions, as well as 
fat embolisms. Fernandez et al. (2005b) also found evidence of fat 
embolism in three beaked whales that stranded 100 km (62 mi) north of 
the Canaries in 2004 during naval exercises. Examinations of several 
other stranded species have also revealed evidence of gas and fat 
embolisms (Arbelo et al., 2005; Jepson et al., 2005a; Mendez et al., 
2005). Most of the afflicted species were deep divers. There is 
speculation that gas and fat embolisms may occur if cetaceans ascend 
unusually quickly when exposed to aversive sounds, or if sound in the 
environment causes the destabilization of existing bubble nuclei 
(Potter, 2004; Arbelo et al., 2005; Fernandez et al. 2005a; Jepson et 
al., 2005b; Cox et al., 2006). Even if gas and fat embolisms can occur 
during exposure to mid-frequency sonar, there is no evidence that that 
type of effect occurs in response to airgun sounds.
    In general, little is known about the potential for seismic survey 
sounds to cause auditory impairment or other physical effects in marine 
mammals. Available data suggest that such effects, if they occur at 
all, would be limited to within short distances of the sound source and 
probably to projects involving large arrays of airguns. The available 
data do not allow for meaningful quantitative predictions of the 
numbers (if any) of marine mammals that might be affected in those 
ways. Marine mammals that show behavioral avoidance of seismic vessels, 
including most baleen whales, some odontocetes, and some pinnipeds, are 
especially unlikely to incur auditory impairment or non-auditory 
physical effects. It is not known whether aversive behavioral responses 
to airgun pulses by deep-diving species could lead to indirect 
physiological problems as apparently can occur upon exposure of some 
beaked whales to mid-frequency sonar (Cox et al., 2006). Also, the 
planned mitigation measures, 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 their auditory organs are 
especially susceptible to injury (Ketten et al., 1993; Ketten, 1995). 
Airgun pulses are less energetic and have slower rise times, and there 
is no proof that they can cause injury, death, or stranding even in the 
case of large airgun arrays. However, the association of mass 
strandings of beaked whales with naval exercises and, in one case, an 
L-DEO seismic survey, has raised the possibility that beaked whales 
exposed to strong pulsed sounds may be especially susceptible to injury 
and/or behavioral reactions that can lead to stranding. Appendix B of 
L-DEO's application provides additional details.
    Seismic pulses and mid-frequency sonar pulses are quite different. 
Sounds produced by airgun arrays are broadband with most of the energy 
below 1 kHz. Typical military mid-frequency sonars operate at 
frequencies of 2-10 kHz, generally with a relatively narrow bandwidth 
at any one time. Thus, it is not appropriate to assume that there is a 
direct connection between the effects of military sonar and seismic 
surveys on marine mammals. However, evidence that sonar pulses can, in 
special circumstances, lead to physical damage and mortality (Balcomb 
and Claridge, 2001; NOAA and USN, 2001; Jepson et al., 2003; Fernandez 
et al., 2004, 2005a; Cox et al., 2006), even if only indirectly, 
suggests that caution is warranted when dealing with exposure of marine 
mammals to any high-intensity pulsed sound.
    There is no conclusive evidence of cetacean strandings as a result 
of exposure to seismic surveys. Speculation concerning a possible link 
between seismic surveys and strandings of humpback whales in Brazil 
(Engel et al., 2004) was not well founded based on available data 
(IAGC, 2004; IWC, 2006). In September 2002, there was a stranding of 
two Cuvier's beaked whales in the Gulf of California, Mexico, when the 
L-DEO vessel R/V Maurice Ewing (Ewing) was operating a 20-gun, 8,490-
in\3\ array in the general area. The link between the stranding and the 
seismic survey was inconclusive and not based on any physical evidence 
(Hogarth, 2002; Yoder, 2002). Nonetheless, that plus the incidents 
involving beaked whale strandings near naval exercises involving use of 
mid-frequency sonar suggests a need for caution when conducting seismic 
surveys in areas occupied by beaked whales. 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.

Potential Effects of Other Acoustic Devices

Multibeam Echosounder Signals
    The Simrad EM 120 12-kHz MBES will be operated from the source 
vessel at some times 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 the 
MBES is at frequencies centered at 12 kHz, and the maximum source level 
is 242 dB re 1 microPa (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 MBES are unlikely to 
be subjected to repeated pulses because of

[[Page 78306]]

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). 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 in order 
to receive the multiple pulses that might result in sufficient exposure 
to cause TTS. Burkhardt et al. (2007) concluded that immediate direct 
auditory injury was possible only if a cetacean dived under the vessel 
into the immediate vicinity of the transducer.
    Navy sonars that have been linked to avoidance reactions and 
stranding of cetaceans (1) generally have a longer pulse duration that 
the Simrad EM120, and (2) are often directed close to horizontally vs. 
more downward for the MBES. The area of possible influence of the MBES 
is much smaller- a narrow band below the source vessel. The duration of 
exposure for a given marine mammal can be much longer for a Navy sonar.
    Marine mammal communications will not be masked appreciably by the 
MBES signals given its low duty cycle and the brief period when an 
individual mammal is likely to be within its beam. Furthermore, in the 
case of baleen whales, the signals (12 kHz) do not overlap with the 
predominant frequencies in the calls, which would avoid significant 
masking.
    Behavioral reactions of free-ranging marine mammals to sonars and 
other sound sources appear to vary by species and circumstance. 
Observed reactions have included silencing and dispersal by sperm 
whales (Watkins et al., 1985), increased vocalizations and no dispersal 
by pilot whales (Rendell and Gordon, 1999), and the previously-
mentioned beachings by beaked whales. During exposure to a 21-25 kHz 
whale-finding sonar with a source level of 215 dB re 1 microPa, gray 
whales showed slight avoidance (approximately 200 m or 656 ft) behavior 
(Frankel, 2005). However, all of those observations are of limited 
relevance to the present situation. Pulse durations from those sonars 
were much longer than those of the MBES, and a given mammal would have 
received many pulses from the naval sonars. During 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.
    Captive bottlenose dolphins and a beluga whale exhibited changes in 
behavior when exposed to 1 s pulsed sounds at frequencies similar to 
those that will be emitted by the MBES used by 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 
either duration or bandwidth as compared with those from an MBES.
    L-DEO is not aware of any data on the reactions of pinnipeds to 
sonar or echosounder sounds at frequencies similar to the 12 kHz 
frequency of the Langseth's MBES. Based on observed pinniped responses 
to other types of pulsed sounds, and 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.
    NMFS believes that the brief exposure of marine mammals to one 
pulse, or small numbers of signals, from the MBES are not likely to 
result in the harassment of marine mammals.
Sub-bottom Profiler Signals
    A SBP will be operated from the source vessel during the planned 
study. Sounds from the SBP 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 mid frequencies, centered at 3.5 kHz. The beamwidth is 
approximately 30[deg] and is directed downward. The SBP on the Langseth 
has a maximum source level of 204 dB re 1 microPam. 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, and if 
the animal was in the area, it would have to pass the transducer at 
close range in order to be subjected to sound levels that could cause 
TTS.
    Marine mammal communications will not be masked appreciably by the 
SBP signals given their directionality and the brief period when an 
individual mammal is likely to be within its beam. Furthermore, in the 
case of most odontocetes, the signals do not overlap with the 
predominant frequencies in the calls, which would avoid significant 
masking.
    Marine mammal behavioral reactions to other pulsed sound sources 
are discussed above, and responses to the SBP are likely to be similar 
to those for other pulsed sources if received at the same levels. The 
pulsed signals from the SBP are somewhat weaker than those from the 
MBES. Therefore, behavioral responses are not expected unless marine 
mammals are very close to the source.
    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.
    NMFS believes that to avoid the potential for permanent 
physiological damage (Level A harassment), cetaceans and pinnipeds 
should not be exposed to pulsed underwater noise at received levels 
exceeding, respectively, 180 and 190 dB re 1 microPa (rms). The 
precautionary nature of these criteria is discussed in Appendix B (6) 
of L-DEO's application, including the fact that the minimum sound level 
necessary to cause permanent hearing impairment is higher, by a 
variable and generally unknown amount, than the level that induces 
barely-detectable TTS and the level associated with the onset of TTS is 
often considered to be a level below which there is no danger of 
permanent damage. NMFS also assumes that cetaceans or pinnipeds exposed 
to levels exceeding 160 dB re 1 microPa (rms) may experience Level B 
harassment.
Sub-bottom Profiler Signals
    An SBP will 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. The beamwidth is 
approximately 30[deg] and is directed downward. The SBP on the Langseth 
has a maximum source level of 204 dB re 1 microPam. 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, and if 
the animal was in the area, it would have to pass the transducer at

[[Page 78307]]

close range in order to be subjected to sound levels that could cause 
TTS.
    Marine mammal communications will not be masked appreciably by the 
SBP 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.
    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.
    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.
    NMFS believes that to avoid the potential for permanent 
physiological damage (Level A harassment), cetaceans and pinnipeds 
should not be exposed to pulsed underwater noise at received levels 
exceeding, respectively 180 and 190 dB re 1microPa (rms). The 
precautionary nature of these criteria is discussed in Appendix B (6) 
of L-DEO's application, including the fact that the maximum sound level 
necessary to cause permanent hearing impairment is higher, by a 
variable and generally unknown amount, than the level that induces 
barely-detectable TTS and the level associated with the onset of TTS is 
often considered to be a level below which there is no danger of 
permanent damage. NMFS also assumes that cetaceans or pinnipeds exposed 
to levels exceeding 160 dB re 1 microPa (rms) may experience Level B 
harassment.
Possible Effects of Acoustic Release Signals
    The acoustic release transponder used to communicate with the OBSs 
uses frequencies of 9-13 kHz. These signals will be used very 
intermittently. It is unlikely that the acoustic release signals would 
have significant effects on marine mammals through masking, 
disturbance, or hearing impairment. Any effects likely would be 
negligible given the brief exposure at presumable low levels.

Estimated Take by Incidental Harassment

    All anticipated takes would be ``takes by harassment,'' involving 
temporary changes in behavior. The proposed mitigation measures are 
expected to minimize the possibility of injurious takes. (However, as 
noted earlier, there is no specific information demonstrating that 
injurious ``takes'' would occur even in the absence of the planned 
mitigation measures.) The sections below describe methods to estimate 
``take by harassment'', and present estimates of the numbers of marine 
mammals that might be affected during the proposed TAIGER seismic 
program. The estimates of ``take by harassment'' are based on 
consideration of the number of marine mammals that might be disturbed 
appreciably by operations with the 36 airgun array to be used during 
approximately 15,902 km of seismic surveys in the waters of the SE Asia 
study area. The main sources of distributional and numerical data used 
in deriving the estimates are described below.
    Empirical data concerning 190, 180, 170, and 160 dB re 1 microPa 
isopleth distances in deep and shallow water were acquired for various 
airgun configurations during the acoustic calibration study of the 
Ewing's 20-airgun 8,600 in\3\ array in 2003 (Tolstoy et al., 2004a,b). 
The results showed that radii around the airguns where the received 
level was 180 dB re 1 microPa rms, the threshold for estimating Level B 
harassment applicable to cetaceans (NMFS, 2000), varied with water 
depth. Similar depth-related variation is likely for the 190-dB re 1 
microPa threshold for estimating Level B harassment applicable to 
cetaceans and the 190-dB re 1 microPa threshold applicable to 
pinnipeds, although these were not measured. The L-DEO model does not 
allow for bottom interactions, and thus is most directly applicable to 
deep water and to relatively short ranges.
    The empirical data indicated that, for deep water (>1,000 m; 3,280 
ft), the L-DEO model (as applied to the Ewing's airgun configurations) 
overestimated the measured received sound levels at a given distance 
(Tolstoy et al., 2004a,b). However, to be conservative, the distances 
predicted by L-DEO's model for the survey will be applied to deep-water 
areas during the proposed study (see Figure 3 and 4 and Table 1 in the 
application). As very few, if any, mammals are expected to occur deeper 
than 2,000 m (6,562 ft), this depth was used as the maximum relevant 
depth.
    Empirical measurements of sounds from the Ewing's airgun arrays 
were not conducted for intermediate depths (100-1,000 m; 328-3,280 ft). 
On the expectation that results would be intermediate, the estimates 
provided by the model for deep-water situations are used to obtain 
estimates for intermediate-depth sites. Corresponding correction 
factors, applied to the modeled radii for the Langseth's airgun 
configuration, will be used during the proposed study for intermediate 
depths (see Table 1 of the application).
    Empirical measurements near the Ewing indicated that in shallow 
water (<100 m; 328 ft), the L-DEO model underestimates actual levels. 
In previous L-DEO projects, the exlusion zones were typically based on 
measured values and ranged from 1.3 to 15 times higher than the modeled 
values depending on the size of the airgun array and the sound level 
measured (Tolstoy et al., 2004b). During the proposed cruise, similar 
correction factors will be applied to derive appropriate shallow-water 
radii from the modeled deep-water radii for the Langseth's airgun 
configuration (see Table 1 of L-DEO's application).
    Using the modeled distances and various correction factors, Table 1 
(from L-DEO's application) shows the distances at which 4 rms sound 
levels are expected to be received from the 36-airgun array and a 
single airgun in three different water depths.
    The anticipated radii of influence of the MBES and the SBP are much 
smaller than those for the airgun array. It is assumed that, during 
simultaneous operations of the airgun array and echosounders, marine 
mammals close enough to be affected by the echosounders would already 
be affected by the airguns. However, whether or not the airguns are 
operating simultaneously with the echosounders, marine mammals are not 
expected to be exposed to sound pressure levels great enough or long 
enough for taking to occur given echosounders' characteristics (e.g., 
narrow downward-directed beam) and other considerations described 
above. Therefore, no additional allowance is included for

[[Page 78308]]

animals that might be affected by sound sources other than airguns
    No systematic aircraft- or ship-based surveys have been conducted 
for marine mammals in waters near Taiwan, and the species of marine 
mammals that occur there are not well known. A few surveys have been 
conducted from small vessels (approximately 10-12 m or 33-40 ft long) 
with low observation platforms (approximately 3 m or 10 ft above sea 
level) as follows:
     Off the east central coast of Taiwan to a maximum of 
approximately 20 km (12.4 mi) from shore in water depths up to 
approximately 1,200 m deep between June 1996 and July 1997 (all 
cetacean; Yang et al., 1999);
     Off the south coast of Taiwan to a distance of 
approximately 50 km (mi) and depths greater than 1,000 m (3,280 ft) 
during April 13-September 9, 2000 (all cetaceans; Wang et al., 2001a);
     Off the west coast of Taiwan close to shore during early 
April-early August, 2002-2006 (Indo-Pacific humpback dolphins; Wang et 
al., 2007); and
     Around and between the Babuyan Islands off northern 
Philippines in waters less than 1,000 m deep during late February-May 
2000-2003 (humpback whales; Acebes et al., 2007).
    The only density calculated by the authors was for the Indo-Pacific 
humpback dolphin (Wang et al., 2007). In addition, a density estimate 
was also available for the Indo-Pacific bottlenose dolphin (Yang et 
al., 2000 in Perrin et al., 2005).
    In the absence of any other density data, L-DEO used the survey 
effort and sightings in Yang et al. (1999) and Wang et al. (2001a) to 
estimate densities of marine mammals in the TAIGER study area. To 
correct for detection bias (bias associated with diminishing 
sightability with increasing lateral distance from the trackline), L-
DEO used mean group sizes given by or calculated from Wang et al. 
(2001a, 2007) and Yang et al., (1999), and a value for f(0) of 5.32 
calculated from the data and density equation in Wang et al. (2007); 
Yang et al. (1999), and Wang et al. (2001a) did not give a value for 
f(0), but they used a vessel and methods similar to those of Wang et 
al. (2007). To correct for availability and perception bias, which are 
attributable to the less than 100 percent probability of sighting an 
animals present along the survey trackline, L-DEO used g(0) values 
calculated using surfacing and dive data from Erickson (1976), Barlow 
and Sexton (1996), Forney and Barlow (1998), and Barlow (1999): 0.154 
for Mesoplodon sp., 0.102 for Cuvier's beaked whale, 0.193 for the 
dwarf sperm whale and Kogia sp., 0.238 for the killer whale, and 1.0 
for delphinids.
    The surveys of Yang et al. (1999) and Wang et al. (2001a) were 
carried out in areas of steep slopes and complex bathymetric features, 
where many cetacean species are known to concentrate. It did not seem 
reasonable to extrapolate those densities to the overall survey area, 
which is predominantly in areas of deep water without complex 
bathymetry. For latter areas, L-DEO used density data from two 5[deg] x 
5[deg] blocks in the eastern tropical Pacific Ocean (ETP) surveyed by 
Ferguson and Barlow (2001): Blocks 87 and 88\2\, bounded by 20[deg] N-
25[deg] N (the same latitudes as the proposed survey area and 115[deg] 
W-125 W, in deep water and just offshore from Mexico. L-DEO then 
calculated an overall estimate weighted by the estimated lengths of 
seismic lines over complex bathymetry or slope (approximately 1,250 km 
or 777 mi) and over deep, flat, or gently sloping bottom (approximately 
14,652 km or 9,104 mi).
    The density estimate for the Indo-Pacific hump-backed dolphin is 
from Wang et al. (2007) and applies only to the population's limited 
range on the west coat of Taiwan. No density data were available for 
the Pacific white-sided or short-beaked common dolphin for the study 
area. As these species are rare in the area, densities are expected to 
be near zero. In addition, density data were unavailable for striped 
and long-beaked common dolphins. As these two species were not seen 
during the above-mentioned surveys and are considered uncommon in the 
TAIGER study area, L-DEO assigned these two species 10 percent of the 
density estimate of the delphinid occurring in similar habitat in the 
area with the lowest density (i.e., pygmy killer whale). Also no 
density estimate was available for finless porpoise. As this species 
was not sighted during surveys of southern Taiwan in 2000 (Wang et al., 
2001a), L-DEO assigned it 10 percent of the lowest density (i.e., Indo-
Pacific bottlenose dolphin). Density data were unavailable for 
Longman's beaked and ginkgo-toothed beaked whales; however, these two 
species are represented by densities for unidentified beaked whales.
    Large whales were not sighted during the surveys by Yang et al. 
(1999) or Wang et al. (2001a). The only available abundance estimate 
for large whales in the area (except that for humpbacks, see below) is 
that of Shimada et al. (2008), who estimated abundances of Bryde's 
whales in several blocks in the northwestern Pacific based on surveys 
in 1998-2002, the closest of which to the proceed survey area is the 
block bounded by 10[deg] N-25[deg] N and 130[deg] E-137.5[deg] E. The 
resulting abundance and area were used to calculate density. Sperm, 
sei, Omura's, fin, minke, and blue whales are less common than Bryde's 
whales in these waters, so L-DEO assigned a density of 10 percent of 
that calculated for Bryde's whale. North Pacific right, and Western 
North Pacific gray whales are unlikely to occur in the TAIGER study 
area, thus, densities were estimated to be zero.
    For humpback whales in the Babuyan Islands, L-DEO used the 
population estimate of Acebes et al. (2007) and applied it to an area 
of approximately 78,000 km\2\, extending from the north coast of Luzon 
to just south of Orchid Island to derive a density estimate. That area 
is a historically well-documented breeding ground that whaling records 
indicate was used until at least the 1960s (Acebes et al., 2007), and 
an area where humpbacks have been sighted more recently.
    There is some uncertainty about the representatives of the density 
data and the assumptions used in the calculations. For example, the 
timing of the surveys of Indo-Pacific humpback dolphins (early April-
early August) and humpback whales (late February-May) overlaps the 
timing of the proposed surveys, but the Bryde's whale surveys (August 
and September), and those of Yang et al. (1999) (year-round) include 
different seasons, and would not be as representative if there are 
seasonal density differences. Perhaps the greatest uncertainty results 
from using survey results from the northeast Pacific Ocean. However, 
the approach used here is believed to be the best available approach. 
Also, to provide some allowance for these uncertainties, ``maximum 
estimates'' as well as ``best estimates'' of the densities present and 
numbers of marine mammals potentially affected have been derived. Best 
estimates for most species are based on average densities from the 
surveys of Yang et al. (1999), Wang et al. (2001a), and Ferguson and 
Barlow (2001), weighted by effort, whereas maximum estimates are based 
on the higher of the two densities from the Taiwan surveys and the 
eastern Pacific survey blocks. For the sperm whales, mysticetes, two 
delphinids (Indo-Pacific humpback and Indo-Pacific bottlenose 
dolphins), as well as for the finless porpoise, the maximum estimates 
are the best estimates multiplied by 1.5. Densities calculated or 
estimated as described above are given in Table 3 of L-DEO's 
application.
    The estimated numbers of individuals potentially exposed on each 
leg of the survey are based on the 160 dB re 1 microPa

[[Page 78309]]

(rms) Level B harassment exposure threshold for cetaceans and 
pinnipeds. It is assumed that marine mammals exposed to airgun sounds 
at these levels might experience disruption of behavioral patterns.
    It should be noted that the following estimates of takes by 
harassment assume that the surveys will be fully completed. As is 
typical during offshore ship surveys, inclement weather and equipment 
malfunctions are likely to cause delays and may limit the number of 
useful line-km to seismic operations that can be undertaken. 
Furthermore, any marine mammal sightings within or near the designated 
EZ will result in the power-down or shut-down of seismic operations as 
a mitigation measure. Thus, the following estimates of the numbers of 
marine mammals exposed to 160-dB sounds probably overestimate the 
actual numbers of marine mammals that might be involved. These 
estimates assume that there will be no weather, equipment, or 
mitigation delays, which is highly unlikely.
    The number of different individuals that may be exposed to airgun 
sounds with received levels [gteqt]160 dB re 1 microPa (rms) on one or 
more occasions was estimated by considering the total marine area that 
would be within the 160-dB radius around the operating airgun array on 
at least one occasion. The number of possible exposures (including 
repeated exposures of the same individuals) can be estimated by 
considering the total marine area that would be within the 160 dB 
radius around the operating airguns, including areas of overlap. In the 
proposed survey, the seismic lines are widely spaces in the survey 
area, and are further spaced in time because the proposed survey, the 
seismic lines are widely spaced in the survey area, and are further 
spaced in time because the proposed survey is planned in discrete legs 
separated by several days. Thus, an individual mammal would not be 
exposed numerous times during the survey; the areas including overlap 
are 1.1-1.3 times the areas excluding overlap, depending on the leg, so 
the numbers of exposures are not discussed further. Moreover, it is 
unlikely that a particular animal would stay in the area during the 
entire survey.
    The number of different individuals potentially exposed to received 
levels [gteqt]160 dB re 1 microPa (rms) was calculated by multiplying:
     The expected species density, either ``mean'' (i.e., best 
estimate) or ``maximum,'' times
     The anticipated minimum area to be ensonified to that 
level during airgun operations excluding 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 (depending on water 
and tow depth) and then calculating the total area within the buffers. 
Areas where overlap occurred were limited and included only once to 
determine the area expected to be ensonified when estimating the number 
of individuals exposed.
    Applying the approach described above, approximately 168,315 km\2\ 
(104,586 mi\2\) would be within the 160-dB isopleth on one or more 
occasions during the survey. Because this approach does not allow for 
turnover in the mammal populations in the study area during the course 
of the survey, the actual number of individuals exposed could be 
underestimated. However, the approach assumes that no cetaceans will 
move away from or toward the trackline as the Langseth approaches in 
response to increasing sound levels prior to the time the levels reach 
160 dB, which will result in overestimates for those species known to 
avoid seismic vessels.

 Table 3. The estimates of the possible numbers of marine mammals exposed to sound levels greater than or equal
    to 160 dB during L-DEO's proposed seismic survey in SE Asia in March-July 2009. The proposed sound source
consists of a 36-airgun, 6,600 in3, array. Received levels are expressed in dB re 1 microPa (rms) (averaged over
 pulse duration), consistent with NMFS' practice. Not all marine mammals will change their behavior when exposed
 to these sound levels, but some may alter their behavior when levels are lower (see text). See Tables 2-4 in L-
                                      DEO's application for further detail.
----------------------------------------------------------------------------------------------------------------
                                              of              of
               Species                   Individuals Exposed      Individuals Exposed       Approx. % Regional
                                              (best)\1\                 (max)\1\          Population (best) \2\
----------------------------------------------------------------------------------------------------------------
Mysticetes
--------------------------------------
Western North Pacific gray whale       0                        0                        0
(Eschrichtius robustus)
----------------------------------------------------------------------------------------------------------------
Western North Pacific right whale      0                        0                        0
(Eubalaena japonica)
----------------------------------------------------------------------------------------------------------------
Humpback whale                         10                       14                       0.94
(Megaptera novaeangliae)
----------------------------------------------------------------------------------------------------------------
Minke whale                            5                        8                        0.02
(Balaenoptera acutorostrata)
----------------------------------------------------------------------------------------------------------------
Bryde's whale                          51                       77                       020
(Balaenoptera brydei)
----------------------------------------------------------------------------------------------------------------
Omura's whale                          5                        8                        N.A.
(Balaenoptera omurai)
----------------------------------------------------------------------------------------------------------------
Sei whale                              5                        8                        0.05
(Balaenoptera borealis)
----------------------------------------------------------------------------------------------------------------
Fin whale                              5                        8                        0.03
(Balaenoptera physalus)
----------------------------------------------------------------------------------------------------------------

[[Page 78310]]

 
Blue whale                             5                        8                        N.A.
(Balaenoptera musculus)
----------------------------------------------------------------------------------------------------------------
Mysticetes
--------------------------------------
Sperm whale                            5                        8                        0.02
(Physeter macrocephalus)
----------------------------------------------------------------------------------------------------------------
Pygmy sperm whale                      0                        0                        N.A.
(Kogia breviceps)
----------------------------------------------------------------------------------------------------------------
Dwarf sperm whale                      806                      1267                     7.19
(Kogia sima)
----------------------------------------------------------------------------------------------------------------
Kogia sp.                              49                       76                       N.A.
----------------------------------------------------------------------------------------------------------------
Cuvier's beaked whale                  64                       143                      0.32
(Ziphius cavirostris)
----------------------------------------------------------------------------------------------------------------
Longman's beaked whale                 0                        0                        N.A.
(Indopacetus pacificus)
----------------------------------------------------------------------------------------------------------------
Blainville's beaked whale              168                      303                      0.66
(Mesoplodon densirostris)
----------------------------------------------------------------------------------------------------------------
Ginkgo-toothed beaked whale            0                        0                        N.A.
(Mesoplodon ginkgodens)
----------------------------------------------------------------------------------------------------------------
Mesoplodon sp. (unidentified) \3\      294                      303                      1.16
----------------------------------------------------------------------------------------------------------------
Unidentified beaked whale \4\          137                      178                      N.A.
----------------------------------------------------------------------------------------------------------------
Rough-toothed dolphin                  252                      1,031                    0.17
(Steno bredanensis)
----------------------------------------------------------------------------------------------------------------
Indo-Pacific humpback dolphin          68                       99                       4.03
(Sousa chinensis)
----------------------------------------------------------------------------------------------------------------
Common bottlenose dolphin              4,606                    6,704                    1.89
(Tursiops truncatus)
----------------------------------------------------------------------------------------------------------------
Indo-Pacific bottlenose dolphin        677                      6,704                    N.A.
(Tursiops aduncus)
----------------------------------------------------------------------------------------------------------------
Pacific white-sided dolphin            0                        0                        0
(Lagenorhynchus obliquidens)
----------------------------------------------------------------------------------------------------------------
Pantropical spotted dolphin            22,902                   26,726                   2.86
(Stenella attenuata)
----------------------------------------------------------------------------------------------------------------
Spinner dolphin                        10,397                   16,835                   1.30
(Stenella longirostris)
----------------------------------------------------------------------------------------------------------------
Striped dolphin                        38                       60                       0.01
(Stenella coeruleoalba)
----------------------------------------------------------------------------------------------------------------
Fraser's dolphin                       18,359                   23,534                   6.35
(Lagenodelphis hoseia)
----------------------------------------------------------------------------------------------------------------
Short-beaked common dolphin            0                        0                        0
(Delphinus delphis)
----------------------------------------------------------------------------------------------------------------
Long-beaked common dolphin             10                       23                       0.01
(Delphinus capensis)
----------------------------------------------------------------------------------------------------------------

[[Page 78311]]

 
Risso's dolphin                        7,940                    12,736                   4.54
(Grampus griseus)
----------------------------------------------------------------------------------------------------------------
Melon-headed whale                     2,534                    3,954                    5.63
(Peponocephala electra)
----------------------------------------------------------------------------------------------------------------
Pygmy killer whale                     380                      599                      0.98
(Feresa attenuata)
----------------------------------------------------------------------------------------------------------------
l killer whale                         865                      905                      2.16
(Pseudorca crassidens)
----------------------------------------------------------------------------------------------------------------
Killer whale                           189                      329                      2.23
(Orcinus orca)
----------------------------------------------------------------------------------------------------------------
Short-finned pilot whale               727                      1,220                    0.15
(Globicephala macrorhynchus)
----------------------------------------------------------------------------------------------------------------
Finless porpoise                       68                       101                      0.66
(Neophocaena phocaenoides)
----------------------------------------------------------------------------------------------------------------
Sirenians
--------------------------------------
Dugong                                 0                        0                        N.A.
(Dugong dugon)
----------------------------------------------------------------------------------------------------------------
N.A. - Data not available or species status was not assessed
\1\ Best estimate and maximum estimate density are from Table 3 of L-DEO's application. There will be no seismic
  acquisition data during Leg 3 of the survey; this, it is not included here in this table.
\2\ Regional population size estimates are from Table 2.
\3\ Requested takes include Blainville's, and ginkgo-toothed beaked whales.
\4\ Requested takes include Cuvier's, Blainville's, ginkgo-toothed, and Longman's beaked whales.

    Table 4 of L-DEO's application shows the best and maximum estimates 
of the number of exposures and the number of individual marine mammals 
that potentially could be exposed to greater than or equal to 160 dB re 
1 microPa (rms) during the different legs of the seismic survey if no 
animals moved away from the survey vessel.
    The ``best estimate'' of the number of individual marine mammals 
that could be exposed to seismic sounds with received levels greater 
than or equal to 160 dB re 1 microPa (rms) (but below Level A 
harassment thresholds) during the survey is shown in Table 4 of L-DEO's 
application and Table 3 (shown above). The ``best estimate'' total 
includes 86 baleen whale individuals, 25 of which are listed as 
Endangered under the ESA: 10 humpback whales (0.94 percent of the 
regional population), 5 sei whales (0.05 percent), 5 fin whales (0.03 
percent), and 5 blue whales (regional population unknown). These 
estimates were derived from the best density estimates calculated for 
these species in the area (see Table 4 of L-DEO's application). In 
addition, 5 sperm whales (0.02 percent of the regional population) as 
well as 68 Indo-Pacific humpback dolphins (4.03 percent population, but 
68.7 percent of the eastern Taiwan Strait (ETC) population), 68 finless 
porpoise (0.7 percent), and 663 beaked whales including Longman's and 
ginkgo-toothed beaked whales. Most (97.7 percent) of the cetaceans 
potentially exposed are delphinids; pantropical spotted, Fraser's, and 
spinner dolphins are estimated to be the most common species in the 
area, with best estimates of 22,902 (2.86 percent of the regional 
population), 18,359 (6.35 percent), and 10,397 (1.3 percent) exposed to 
greater or equal to 160 dB re microPa (rms) respectively.
Potential Effects on Marine Mammal Habitat
    The proposed L-DEO 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, as described above. The following sections briefly 
review effects of airguns on fish and invertebrates, and more details 
are included in L-DEO's application and EA, respectively.
Potential Effects on Fish and Invertebrates
    One reason for the adoption of airguns as the standard energy 
source for marine seismic surveys is that, unlike explosives, they have 
not been associated with large-scale fish kills. However, existing 
information on the impacts of seismic surveys on marine fish 
populations is very limited (see Appendix D of L-DEO's EA). There are 
three types of potential effects on fish and invertebrates from 
exposure to seismic surveys: (1) pathological, (2) physiological, and 
(3) behavioral. Pathological effects involve lethal and temporary or 
permanent sub-lethal injury. Physiological effects involve temporary 
and permanent primary and secondary stress responses, such as changes 
in levels of enzymes and proteins. Behavioral effects refer to 
temporary and (if they occur) permanent

[[Page 78312]]

changes in exhibited behavior (e.g., startle and avoidance behavior). 
The three categories are interrelated in complex ways. For example, it 
is possible that certain physiological and behavioral changes 
potentially could lead to an ultimate pathological effect on 
individuals (i.e., mortality).
    The specific received sound levels at which permanent adverse 
effects to fish potentially could occur are little studied and largely 
unknown. Furthermore, the available information on the impacts of 
seismic surveys on marine fish is from studies of individuals or 
portions of a population; there have been no studies at the population 
scale. The studies of individual fish have often been on caged fish 
that were exposed to airgun pulses in situations not representative of 
an actual seismic survey. Thus, available information provides limited 
insight on possible real-world effects at the ocean or population 
scale. This makes drawing conclusions about impacts on fish problematic 
because ultimately, the most important aspect of potential impacts 
relates to how exposure to seismic survey sound affects marine fish 
populations and their viability, including their availability to 
fisheries.
    The following sections provide a general synopsis of available 
information on the effects of exposure to seismic and other 
anthropogenic sound as relevant to fish. The information comprises 
results from scientific studies of varying degrees of rigor plus some 
anecdotal information. Some of the data sources may have serious 
shortcomings in methods, analysis, interpretation, and reproducibility 
that must be considered when interpreting their results (see Hastings 
and Popper, 2005). Potential adverse effects of the program's sound 
sources on marine fish are then noted.
    Pathological Effects - The potential for pathological damage to 
hearing structures in fish depends on the energy level of the received 
sound and the physiology and hearing capability of the species in 
question (see Appendix D of L-DEO's EA). For a given sound to result in 
hearing loss, the sound must exceed, by some specific amount, the 
hearing threshold of the fish for that sound (Popper, 2005). The 
consequences of temporary or permanent hearing loss in individual fish 
on a fish population is unknown; however, it likely depends on the 
number of individuals affected and whether critical behaviors involving 
sound (e.g., predator avoidance, prey capture, orientation and 
navigation, reproduction, etc.) are adversely affected.
    Little is known about the mechanisms and characteristics of damage 
to fish that may be inflicted by exposure to seismic survey sounds. Few 
data have been presented in the peer-reviewed scientific literature. As 
far as we know, there are only two valid papers with proper 
experimental methods, controls, and careful pathological investigation 
implicating sounds produced by actual seismic survey airguns with 
adverse anatomical effects. One such study indicated anatomical damage 
and the second indicated TTS in fish hearing. The anatomical case is 
McCauley et al. (2003), who found that exposure to airgun sound caused 
observable anatomical damage to the auditory maculae of ``pink 
snapper'' (Pagrus auratus). This damage in the ears had not been 
repaired in fish sacrificed and examined almost 2 months after 
exposure. On the other hand, Popper et al. (2005) documented only TTS 
(as determined by auditory brainstem response) in 2 of 3 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\.s showed no hearing loss. During both studies, the 
repetitive exposure to sound was greater than would have occurred 
during a typical seismic survey. However, the substantial low-frequency 
energy produced by the airgun arrays [less than approximately 400 Hz in 
the study by McCauley et al. (2003) and less than approximately 200 Hz 
in Popper et al. (2005)] likely did not propagate to the fish because 
the water in the study areas was very shallow (approximately 9 m in the 
former case and less than 2 m in the latter). Water depth sets a lower 
limit on the lowest sound frequency that will propagate (the ``cutoff 
frequency'') at about one-quarter wavelength (Urick, 1983; Rogers and 
Cox, 1988).
    In water, acute injury and death of organisms exposed to seismic 
energy depends primarily on two features of the sound source: (1) the 
received peak pressure, and (2) the time required for the pressure to 
rise and decay (Hubbs and Rechnitzer, 1951; Wardle et al., 2001). 
Generally, the higher the received pressure and the less time it takes 
for the pressure to rise and decay, the greater the chance of acute 
pathological effects. Considering the peak pressure and rise/decay time 
characteristics of seismic airgun arrays used today, the pathological 
zone for fish and invertebrates would be expected to be within a few 
meters of the seismic source (Buchanan et al., 2002). 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, 2000b; 
Bjarti, 2002; Hassel et al., 2003; Popper et al., 2005).
    Except for these two studies, at least with airgun-generated sound 
treatments, most contributions rely on rather subjective assays such as 
fish ``alarm'' or ``startle response'' or changes in catch rates by 
fishers. These observations are important in that they attempt to use 
the levels of exposures that are likely to be encountered by most free-
ranging fish in actual survey areas. However, the associated sound 
stimuli are often poorly described, and the biological assays are 
varied (Hastings and Popper, 2005).
    Wardle et al. (2001) suggested that in water, acute injury and 
death of organisms exposed to seismic energy depends primarily on two 
features of the sound source: (1) the received peak pressure, and (2) 
the time required for the pressure to rise and decay. Generally, as 
received pressure increases, the period for the pressure to rise and 
decay decreases, and the chance of acute pathological effects 
increases. 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 and invertebrates 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).
    Some studies have reported, some equivocally, that mortality of 
fish, fish eggs, or larvae can occur close to seismic sources 
(Kostyuchenko, 1973; Dalen and Knutsen, 1986; Booman et al., 1996; 
Dalen et al., 1996). Some of the reports claimed seismic effects from 
treatments quite different from actual seismic survey sounds or even 
reasonable surrogates. Saetre and Ona (1996) applied a 'worst-case 
scenario' mathematical model to investigate the effects of seismic 
energy on fish eggs and larvae. They concluded that mortality rates 
caused by exposure to seismic surveys are so low, as compared to 
natural mortality rates, that the impact of seismic surveying on 
recruitment to a fish stock must be regarded as insignificant.
    Physiological Effects - Physiological effects refer to cellular 
and/or biochemical responses of fish to acoustic stress. Such stress 
potentially could affect fish populations by increasing mortality or 
reducing reproductive success. Primary and

[[Page 78313]]

secondary stress responses of fish after exposure to seismic survey 
sound appear to be temporary in all studies done to date (Sverdrup et 
al., 1994; McCauley et al., 2000a, 2000b). The periods necessary for 
the biochemical changes to return to normal are variable, and depend on 
numerous aspects of the biology of the species and of the sound 
stimulus (see Appendix D of L-DEO's EA).
    Summary of Physical (Pathological and Physiological) Effects - As 
indicated in the preceding general discussion, there is a relative lack 
of knowledge about the potential physical (pathological and 
physiological) effects of seismic energy on marine fish and 
invertebrates. Available data suggest that there may be physical 
impacts on egg, larval, juvenile, and adult stages at very close range. 
Considering typical source levels associated with commercial seismic 
arrays, close proximity to the source would result in exposure to very 
high energy levels. Whereas egg and larval stages are not able to 
escape such exposures, juveniles and adults most likely would avoid it. 
In the case of eggs and larvae, it is likely that the numbers adversely 
affected by such exposure would not be that different from those 
succumbing to natural mortality. Limited data regarding physiological 
impacts on fish and invertebrates indicate that these impacts are short 
term and are most apparent after exposure at close range.
    The proposed seismic program for 2009 is predicted to have 
negligible to low physical effects on the various stags of fish and 
invertebrates for its relatively short duration (approximately 103 
days) and unique survey lines extent. Therefore, physical effects of 
the proposed program on fish and invertebrates would not be 
significant.
    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; L kkeborg, 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 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.
    For marine invertebrates, behavioral changes could potentially 
affect such aspects as reproductive success, distribution, 
susceptibility to predation, and catchability by fisheries. Studies of 
squid indicated startle responses (McCauley et al., 2000a,b). In other 
cases, no behavioral impacts were noted (e.g., crustaceans in Christian 
et al., 2003, 2004; DFO, 2004). There have been anecdotal reports of 
reduced catch rates of shrimp shortly after exposure to seismic 
surveys; however, other studies have not observed any significant 
changes in shrimp catch rate (Andriguetto-Filho et al., 2005). Parry 
and Gason (2006) reported no changes in rock lobster CPUE during or 
after seismic surveys off western Victoria, Australia, from 1978-2004. 
Any adverse effects on crustacean and cephalopod behavior or fisheries 
attributable to seismic survey sound depend on the species in question 
and the nature of the fishery (season, duration, fishing method). 
Additional information regarding the behavioral effects of seismic on 
invertebrates is contained in Appendix D in NSF's EA
    Summary of Behavioral Effects - As is the case with pathological 
and physiological effects of seismic on fish and invertebrates, 
available information is relatively scant and often contradictory. 
There have been well-documented observations of fish and invertebrates 
exhibiting behaviors that appeared to be responses to exposure to 
seismic energy (i.e., startle response, change in swimming direction 
and speed, and change in vertical distribution), but the ultimate 
importance of those behaviors is unclear. Some studies indicate that 
such behavioral changes are very temporary, whereas others imply that 
fish might not resume pre-seismic behaviors or distributions for a 
number of days. There appears to be a great deal of inter- and intra-
specific variability. In the case of finfish, three general types of 
behavioral responses have been identified: startle, alarm, and 
avoidance. The type of behavioral reaction appears to depend on many 
factors, including the type of behavior being exhibited before 
exposure, and proximity and energy level of sound source.
    During the proposed study, only a small fraction of the available 
habitat would be ensonified at any given time, and fish species would 
return to their pre-disturbance behavior once the seismic activity 
ceased. The proposed seismic program is predicted to have negligible to 
low behavioral effects on the various life stages of the fish and 
invertebrates during its relatively short duration and extent.
    Because of the reasons noted above and the nature of the proposed 
activities, the proposed operations are not expected to have any 
habitat-related effects that could cause significant or long-term 
consequences for individual marine mammals or their populations or 
stocks. Similarly, any effects to food sources are expected to be 
negligible.

Subsistence Activities

    There is no legal subsistence hunting for marine mammals in the 
waters of Taiwan, China, or the Philippines, so the proposed activities 
will not have any impact on the availability of the species or stocks 
for subsistence users. Today, Japan still hunts whales and dolphins for 
``scientific'' purposes. Up until 1990, a drive fishery of false killer 
whales occurred in the Penghu Islands, Taiwan, where dozens of whales 
were taken. Although killing and capturing of cetaceans has been 
prohibited in Taiwan since August 1990 under the Wildlife Conservation 
Law (Zhou et al., 1995; Chou, 2004), illegal harpooning still occurs 
(Perrin et al., 2005). Until the 1990's, there was a significant hunt 
of around 200 to 300 dolphins annually in the Philippines. Catches 
included dwarf sperm, melon-headed, and short-finned pilot whales, as 
well as bottlenose, spinner, Fraser's, and Risso's dolphins (Rudolph 
and Smeenk, 2002). Reports also indicate that perhaps 5 Bryde's whales 
were caught annually (Rudolph and Smeenk, 2002), although the last 
Bryde's whales were caught in 1996 (Reeves, 2002). Successive bans on

[[Page 78314]]

the harvesting of whales and dolphins were issued by the Philippine 
Government during the 1990's.

Proposed Mitigation and Monitoring

    Mitigation and monitoring measures proposed to be implemented for 
the proposed seismic survey have been developed and refined during 
previous L-DEO seismic studies and associated environmental assessments 
(EAs), IHA applications, and IHAs. The mitigation and monitoring 
measures described herein represent a combination of procedures 
required by past IHAs for other similar projects and on recommended 
best practices in Richardson et al. (1995), Pierson et al. (1998), and 
Weir and Dolman (2007). The measures are described in detail below.
    Mitigation measures that will be adopted during the proposed TAIGER 
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; (5) 
spatial and temporal avoidance of sensitive species and areas, provided 
that doing so will not compromise operational safety requirements; and 
(6) special procedures for situations or species of concern, e.g., 
emergency shutdown procedures if a North Pacific right whale or a 
Western Pacific gray whale is sighted from any distance (see ``shut-
down procedures'' and ``special procedures for species of concern,'' 
below) and minimization of approaches to slopes and submarine canyons, 
if possible, because of sensitivity for beaked whales. The thresholds 
for estimating take are also used in connection with proposed 
mitigation.

Vessel-based Visual Monitoring

    Marine Mammal Visual Observers (MMVOs) will be based aboard the 
seismic source vessel and will watch for marine mammals near the vessel 
during daytime airgun operations and during start-ups of airguns at 
night. MMVOs will also watch for marine mammals near the seismic vessel 
for at least 30 minutes prior to the start of airgun operations and 
after an extended shutdown of the airguns. When feasible MMVOs will 
also make observations during daytime periods when the seismic system 
is not operating for comparison of sighting rates and animal behavior 
with vs. without airgun operations. Based on MMVO observations, the 
airguns will be powered down, or if necessary, shut down completely 
(see below), when marine mammals are detected within or about to enter 
a designated EZ. The MMVOs will continue to maintain watch to determine 
when the animal(s) are outside the safety radius, and airgun operations 
will not resume until the animal has left that zone. The predicted 
distances for the safety radius are listed according to the sound 
source, water depth, and received isopleths in Table 1.
    During seismic operations in SE Asia, at least 3 MMVOs will be 
based aboard the Langseth. MMVOs will be appointed by L-DEO with NMFS 
concurrence. At least one MMVO and when practical two, will monitor the 
EZ for marine mammals during ongoing daytime operations and nighttime 
startups of the airguns. Use of two simultaneous MMVOs will increase 
the effectiveness of detecting animals near the sound source. MMVO(s) 
will be on duty in shift of duration no longer than 4 hours. The vessel 
crew will also be instructed to assist in detecting marine mammals and 
implementing mitigation measures (if practical). 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 observations. 
When stationed on the observation platform, the eye level will be 
approximately 18 m (58 ft) above sea level, and the observer will have 
a good view around the entire vessel. During the daytime, the MMVO(s) 
will scan the area around the vessel systematically with reticle 
binoculars (e.g., 7x50 Fujinon), Big-eye binoculars (25x150), and with 
the naked eye. During darkness, night vision devices will be available 
(ITT F500 Series Generation 3 binocular-image 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 MMVOs to estimate 
distances visually, but are generally not useful in measuring distances 
to animals directly; that is done primarily with the reticles on the 
binocular's lenses.
    Speed or Course Alteration - If a marine mammal is detected outside 
the safety radius and based on its position and the relative motion, is 
likely to enter the EZ, 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(s) (relative to the seismic vessel) will then be closely 
monitored to determine whether the animal(s) is approaching the 
applicable EZ. If the animal appears likely to enter the EZ, 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, major course and speed adjustments are often 
impractical when towing long seismic streamers and large source arrays, 
thus alternative mitigation measures (see below) will need to be 
implemented.
    Power-down Procedures - A power-down involves reducing the number 
of airguns in use such that the radius of the of the 180 dB or 190 dB 
zone is decreased to the extent that marine mammals are no longer in or 
about to enter the EZ. 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 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 is detected outside the EZ but is likely to 
enter it, and if the vessel's speed and/or course cannot be changed to 
avoid the animal(s) entering the EZ, the airguns will be powered down 
to a single airgun before the animal is within the EZ. Likewise, if a 
mammal 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 is detected 
within or near the smaller EZ around that single airgun (see Table 1 of 
L-DEO's application and Table 1 above), all airguns will be shut down 
(see next subsection).
    Following a power-down, airgun activity will not resume until the 
marine mammal is outside the EZ for the full array. The animal will be 
considered to have cleared the EZ if it:
    (1) Is visually observed to have left the EZ, or
    (2) Has not been seen within the EZ for 15 minutes in the case of 
small odontocetes and pinnipeds; or
    (3) Has not been seen within the EZ for 30 minutes in the case of 
mysticetes and large odontocetes, including sperm, pygmy sperm, dwarf 
sperm, and beaked whales.
    During airgun operations following a power-down (or shut-down) 
whose duration has exceeded the limits specified above and subsequent 
animal departures, the airgun array will be ramped-up gradually. Ramp-
up procedures are described below.
    Shut-down Procedures - The operating airguns(s) will be shut-down 
if a marine mammal is detected within

[[Page 78315]]

or approaching the EZ for a single airgun source. Shut-downs will be 
implemented (1) if an animal enters the EZ of the single airgun after a 
power-down has been initiated, or (2) if an animal is initially seen 
within the EZ of a single airgun when more than one airgun (typically 
the full array) is operating. Airgun activity will not resume until the 
marine mammal has cleared the EZ, or until the 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.
    Considering the conservation status for North Pacific right whales 
and Western North Pacific gray whales, the airgun(s) will be shut down 
immediately if either of these species are observed, regardless of the 
distance from the Langseth. Ramp-up will only begin if the right or 
gray whale has not been seen for 30 min.
    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 8 minutes. This period is based on the largest modeled 
180 dB radius for the 36-airgun array (see Table 1 of L-DEO's 
application and Table 1 here) in relation to the planned speed of the 
Langseth while shooting. Similar periods (approximately 8-10 minutes) 
were used during previous L-DEO surveys.
    Ramp-up will begin with the smallest airgun 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 approximately 35 minutes. During ramp-up, the 
MMVOs will monitor the EZ, and if marine mammals 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 other 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 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 marine mammal is sighted within or near the applicable 
EZ during the day or close to the vessel at night.
    Temporal and Spatial Avoidance - The Langseth will not acquire 
seismic data in the humpback winter concentration areas during the 
early part of the seismic program, if practicable. North Pacific 
humpback whales are known to winter and calve around Ogasawara and 
Ryuku Islands in southern Japan and in the Babuyan Islands in Luzon 
Strait in the northern Philippines (Perry et al., 1999a; Acebes et al., 
2007; Calambokidis et al., 2008). In the Luzon Strait, the whales may 
arrive in the area as early as November and leave in May or even June, 
with a peak occurrence during February through March or April (Acebes 
et al., 2007). The Langseth will attempt to avoid these wintering areas 
at the time of peak occurrence, by surveying the lines near the Ryuku 
Islands and Babuyan Islands as late as possible during each leg of the 
cruise.
    Due to the conservation status of Indo-Pacific humpback dolphins in 
Taiwan Strait, seismic operations will not occur in water depths less 
than 20 m (65.6 ft) and within at least 2 km (1.2 mi) from the 
Taiwanese shore. Also, when possible, seismic surveying will only take 
place at least 8-10 km (5-6.2 mi) from the Taiwanese coast, 
particularly the central western coast (approximately from Taixi to 
Tongshiao), to minimize the potential of exposing these threatened 
dolphins to SPLs greater than 160 dB re 1 microPa (rms).
    Procedures for Species of Concern - Several species of concern 
could occur in the study area. Special mitigation procedures will be 
used for these species as follows:
    (1) The airguns will be shut down if a North Pacific right whale 
and/or Western Pacific gray whale is sighted at any distance from the 
vessel;
    (2) Because of the sensitivity of beaked whales, approach to slopes 
and submarine canyons will be minimized, if possible, during the 
proposed survey.

Passive Acoustic Monitoring

    Passive Acoustic Monitoring (PAM) will take place to complement the 
visual monitoring program, if practicable. Visual monitoring typically 
is not effective during periods of poor visibility (e.g., 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 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 condition and processing system 
will be located. The lead-in from the hydrophone array is approximately 
400 m (1,312 ft) long, and the active part of the hydrophone is 
approximately 56 m (184 ft) long. The hydrophone array is typically 
towed at depths less than 20 m (65.6 ft).
    The towed hydrophone array will be monitored 24 hours per day while 
at the survey area during airgun operations, and also during most 
periods when the Langseth is underway while the airguns are not 
operating. One Marine Mammal Observer (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 hours. Besides 
the ``visual'' MMOs, an additional MMO with primary responsibility for 
PAM will also be aboard. However, 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, the acoustic MMO will, if visual 
observations are in progress, contact the MMVO immediately to alert 
him/her to the presence of the cetacean(s) (if they have not already 
been seen), and to allow a power down or shutdown 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

[[Page 78316]]

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.
    L-DEO will coordinate the planned marine mammal monitoring program 
associated with the TAIGER seismic survey in SE Asia with other parties 
that may have interest in the area and/or be conducting marine mammal 
studies in the same region during the proposed seismic survey. L-DEO 
and NSF will coordinate with Taiwan, China, Japan, and the Philippines, 
as well as applicable U.S. agencies (e.g., NMFS), and will comply with 
their requirements.

Proposed Reporting

MMVO Data and Documentation

    MMVOs will record data to estimate the numbers of marine mammals 
exposed to various received sound levels and to document apparent 
disturbance reactions or lack thereof. Data will be used to estimate 
numbers of animals potentially `taken' by harassment (as defined in the 
MMPA). They will also provide information needed to order a shutdown of 
the seismic source when a marine mammal or sea turtles is within or 
near the EZ.
    When a sighting is made, the following information about the 
sighting will be recorded:
    (1) Species, group size, and 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 seismic source or vessel (e.g., 
none, avoidance, approach, paralleling, etc.); and behavioral pace.
    (2) Time, location, heading, speed, activity of the vessel, sea 
state, visibility, cloud cover, and sun glare.
    The data listed (time, location, etc.) 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, as well as information regarding seismic source 
shutdown, will be recorded in a standardized format. Data accuracy will 
be verified by the MMVOs at sea, and preliminary reports will be 
prepared during the field program and summaries forwarded to the 
operating institution's shore facility and to NSF weekly or more 
frequently. MMVO observations will provide the following information:
    (1) The basis for decisions about powering down or shutting down 
airgun arrays.
    (2) Information needed to estimate the number of marine mammals 
potentially `taken by harassment.' These data will be reported to NMFS 
per terms of MMPA authorizations or regulations.
    (3) Data on the occurrence, distribution, and activities of marine 
mammals in the area where the seismic study is conducted.
    (4) Data on the behavior and movement patterns of marine mammals 
seen at times with and without seismic activity.
    A report will be submitted to NMFS within 90 days after the end of 
the cruise. The report will describe the operations that were conducted 
and sightings of marine mammals near the operations. The report will be 
submitted to NMFS, providing full documentation of methods, results, 
and interpretation pertaining to all monitoring. The 90-day report will 
summarize the dates and locations of seismic operations, and all marine 
mammal sightings (dates, times, locations, activities, associated 
seismic survey activities). The report will also include estimates of 
the amount and nature of potential ``take'' of marine mammals by 
harassment or in other ways.
    All injured or dead marine mammals (regardless of cause) will 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.

Endangered Species Act (ESA)

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

National Environmental Policy Act (NEPA)

    NSF prepared an Environmental Assessment (EA) of a Marine 
Geophysical Survey by the R/V Marcus G. Langseth in Southeast Asia, 
March-July 2009. NMFS 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.

Preliminary Determinations

    NMFS has preliminarily determined that the impact of conducting the 
seismic survey in SE Asia may result, at worst, in a temporary 
modification in behavior (Level B harassment) of small numbers of 
marine mammals. Further, this activity is expected to result in a 
negligible impact on the affected species or stocks. The provision 
requiring that the activity not have an unmitigable impact on the 
availability of the affected species or stock for subsistence uses is 
not implicated for this proposed action.
    For reasons stated previously in this document, this determination 
is supported by: (1) the likelihood that, given sufficient notice 
through relatively slow ship speed, marine mammals are expected to move 
away from a noise source that is annoying prior to its becoming 
potentially injurious; (2) the fact that cetaceans would have to be 
closer than 950 m (0.6 mi) in deep water, 1,425 m (0.9 mi) at 
intermediate depths, and 3,694 m (2.3 mi) in shallow water when the 
full array is in use at a 9 m (29.5 ft) tow depth from the vessel to be 
exposed to levels of sound (180 dB) believed to have even a minimal 
chance of causing TTS; (3) the fact that marine mammals would have to 
be closer than 6,000 m (3.7 mi) in deep water, 6,667 m (4.1 mi) at 
intermediate depths, and 8,000 m (4.9 mi) in shallow water when the 
full array is in use at a 9 m (29.5 ft) tow depth from the vessel to be 
exposed to levels of sound (160 dB) believed to have even a minimal 
chance at causing TTS; and (4) the likelihood that marine mammal 
detection ability by trained observers is high at that short distance 
from the vessel. As a result, no take by injury or death is 
anticipated, and the potential for temporary or permanent hearing 
impairment is very low and will be avoided through the incorporation of 
the proposed mitigation measures.
    While the number of marine mammals potentially incidentally 
harassed will depend on the distribution and abundance of marine 
mammals in the vicinity of the survey activity, the number of potential 
harassment takings is estimated to be small, less than a few percent of 
any of the estimated population sizes, and has been mitigated to the 
lowest level practicable through incorporation of the measures 
mentioned previously in this document.

Proposed Authorization

    As a result of these preliminary determinations, NMFS proposes to 
issue

[[Page 78317]]

an IHA to L-DEO for conducting a marine geophysical survey in Southeast 
Asia from March-July, 2009, provided the previously mentioned 
mitigation, monitoring, and reporting requirements are incorporated.

    Dated: December 15, 2008.
James H. Lecky,
Director, Office of Protected Resources, National Marine Fisheries 
Service.
[FR Doc. E8-30365 Filed 12-19-08; 8:45 am]
BILLING CODE 3510-22-S