Federal Register / Vol. 74, No. 88 / Friday, May 8, 2009 / Notices 21631 

proposed action. The human 

environment is defined as ‘‘the natural 

and physical environment and the 

relationship of people with that 

environment’’ (40 CFR 1508.14). In the 

context of the EIS, the human 

environment could include air quality, 

water quality, underwater noise levels, 

socioeconomic resources, fisheries, and 

environmental justice. 

Comments concerning this 

environmental review process should be 

directed to NMFS (see ADDRESSES). See 

FOR FURTHER INFORMATION CONTACT

Alexis Gutierrez at 

Alexis.Gutierrez@noaa.gov or at 301– 

713–2322 for questions. All comments 

and material received, including names 

and addresses, will become part of the 

administrative record and may be 

released to the public. 

Authority: The environmental review 

of the phase one of the Strategy for Sea 

Turtle Conservation and Recovery in 

Relation to Atlantic Ocean and Gulf of 

Mexico Fisheries will be conducted 

under the authority and in accordance 

with the requirements of the National 

Environmental Policy Act of 1969, as 

amended (42 U.S.C. 4321 et seq.), 

National Environmental Policy Act 

Regulations (40 CFR parts, 1500 through 

1508), other appropriate Federal laws 

and regulations, and policies and 

procedures of NOAA and NMFS for 

compliance with those regulations. 

Scoping Meetings Code of Conduct 

The public is asked to follow the 

following code of conduct at the scoping 

meetings. At the beginning of each 

meeting, a representative of NMFS will 

explain the ground rules (e.g., alcohol is 

prohibited from the meeting room; 

attendees will be called to give their 

comments in the order in which they 

registered to speak; each attendee will 

have an equal amount of time to speak; 

and attendees may not interrupt one 

another). The NMFS representative will 

structure the meeting so that all 

attending members of the public will be 

able to comment, if they so choose, 

regardless of the controversial nature of 

the subject(s). Attendees are expected to 

respect the ground rules, and those that 

do not will be asked to leave the 

meeting. 

Special Accommodations 

The scoping meetings are physically 

accessible to people with disabilities. 

Requests for sign language 

interpretation or other auxiliary aids 

should be directed to one of the contacts 

(see FOR FURTHER INFORMATION CONTACT) 

at least 7 days prior to the meeting. See 

Council meeting announcement for 

accessibility information for the 

briefings to the councils. 

Dated: May 1, 2009. 

Katy Vincent, 

Acting Deputy Director, Office of Protected 

Resources, National Marine Fisheries Service. 

[FR Doc. E9–10674 Filed 5–7–09; 8:45 am] 

BILLING CODE 3510–22–S 

DEPARTMENT OF COMMERCE 

National Oceanic and Atmospheric 

Administration 

RIN 0648–XI63 

Incidental Takes of Marine Mammals 

During Specified Activities; Marine 

Geophysical Survey in the Northeast 

Pacific Ocean, August – October 2009 

AGENCY: National Marine Fisheries 

Service (NMFS), National Oceanic and 

Atmospheric Administration (NOAA), 

Commerce. 

ACTION: Notice; proposed incidental 

take authorization; request for 

comments. 

SUMMARY: NMFS has received an 

application from the Lamont-Doherty 

Earth Observatory (L-DEO), a part of 

Columbia University, for an Incidental 

Harassment Authorization (IHA) to take 

small numbers of marine mammals, by 

harassment, incidental to conducting a 

seismic survey in the northeast Pacific 

Ocean. Pursuant to the Marine Mammal 

Protection Act (MMPA), NMFS requests 

comments on its proposal to authorize 

L-DEO to take, by Level B harassment 

only, small numbers of marine 

mammals incidental to conducting a 

marine seismic survey during August 

through October, 2009. 

DATES: Comments and information must 

be received no later than June 8, 2009. 

ADDRESSES: Comments on the 

application should be addressed to 

Michael Payne, Chief, Permits, 

Conservation and Education Division, 

Office of Protected Resources, National 

Marine Fisheries Service, 1315 EastWest Highway, Silver Spring, MD 

20910–3225. The mailbox address for 

providing email comments is PR1.0648– 

XI63@noaa.gov. Comments sent via email, including all attachments, must 

not exceed a 10–megabyte file size. 

All comments received are a part of 

the public record and will generally be 

posted to http://www.nmfs.noaa.gov/pr/ 

permits/incidental.htm#applications 

without change. All Personal Identifying 

Information (for example, name, 

address, etc.) voluntarily submitted by 

the commenter may be publicly 

accessible. Do not submit confidential 

business information or otherwise 

sensitive or protected information. 

A copy of the application containing 

a list of the references used in this 

document may be obtained by writing to 

the address specified above, telephoning 

the contact listed below (see FOR

FURTHER INFORMATION CONTACT), or 

visiting the internet at: http:// 

www.nmfs.noaa.gov/pr/permits/ 

incidental.htm#applications. 

Documents cited in this notice may be 

viewed, by appointment, during regular 

business hours, at the aforementioned 

address. 

FOR FURTHER INFORMATION CONTACT: 

Jeannine Cody or Howard Goldstein, 

Office of Protected Resources, NMFS, 

(301) 713–2289. 

SUPPLEMENTARY INFORMATION: 

Background 

Sections 101(a)(5)(A) and (D) of the 

MMPA (16 U.S.C. 1361 et seq.) direct 

the Secretary of Commerce (Secretary) 

to allow, upon request, the incidental, 

but not intentional, taking of marine 

mammals by United States citizens who 

engage in a specified activity (other than 

commercial fishing) within a specified 

geographical region if certain findings 

are made and either regulations are 

issued or, if the taking is limited to 

harassment, a notice of a proposed 

authorization is provided to the public 

for review. 

Authorization for incidental taking 

shall be granted if NMFS finds that the 

taking will have a negligible impact on 

the species or stock(s), will not have an 

unmitigable adverse impact on the 

availability of the species or stock(s) for 

subsistence uses, and if the permissible 

methods of taking and requirements 

pertaining to the mitigation, monitoring 

and reporting of such takings are set 

forth. NMFS has defined ‘‘negligible 

impact’’ in 50 CFR 216.103 as ’’...an 

impact resulting from the specified 

activity that cannot be reasonably 

expected to, and is not reasonably likely 

to, adversely affect the species or stock 

through effects on annual rates of 

recruitment or survival.’’ 

Section 101(a)(5)(D) of the MMPA 

established an expedited process by 

which citizens of the United States can 

apply for an authorization to 

incidentally take small numbers of 

marine mammals by harassment. Except 

with respect to certain activities not 

pertinent here, the MMPA defines 

‘‘harassment’’ as: 

any act of pursuit, torment, or annoyance 

which (i) has the potential to injure a marine 

mammal or marine mammal stock in the wild 

[ALevel A harassment@]; or (ii) has the 

potential to disturb a marine mammal or 

marine mammal stock in the wild by causing 


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21632 Federal Register / Vol. 74, No. 88 / Friday, May 8, 2009 / Notices 

disruption of behavioral patterns, including, 

but not limited to, migration, breathing, 

nursing, breeding, feeding, or sheltering 

[ALevel B harassment@]. 

Section 101(a)(5)(D) establishes a 45– 

day time limit for NMFS= review of an 

application followed by a 30–day public 

notice and comment period on any 

proposed authorizations for the 

incidental harassment of small numbers 

of marine mammals. Not later than 45 

days after the close of the public 

comment period, if the Secretary makes 

the findings set forth in Section 

101(a)(5)(D)(i), the Secretary shall issue 

or deny issuance of the authorization 

with appropriate conditions to meet the 

requirements of clause 101(a)(5)(D)(ii). 

Summary of Request 

On February 11, 2009, NMFS received 

an application from L-DEO for the 

taking by Level B harassment only, of 

small numbers of 33 species of marine 

mammals incidental to conducting a 

marine seismic survey within the 

Exclusive Economic Zone (EEZ) of 

Canada in the northeast Pacific Ocean 

during August through October 2009. LDEO, with research funding from the 

NSF, is conducting the geophysical data 

acquisition activities with onboard 

assistance by Drs. Toomey and Hooft 

from the University of Oregon, and Dr. 

Wilcock from the University of 

Washington. 

This survey, also known as the 

Endeavor Tomography (ETOMO) Study, 

will take place approximately 250 

kilometers (km) (155 miles (mi)) 

southwest of Vancouver Island, British 

Columbia, within the Canadian 

Endeavour Marine Protected Area 

(MPA) along an 80–km- (50- mi-) long 

section of the Endeavour segment of the 

Juan de Fuca Ridge. The Endeavor MPA 

is a unique ecosystem consisting of 

hydrothermal vents and associated 

fauna. Canada officially designated the 

area as an MPA in March 2003. 

However, scientific research for the 

conservation, protection and 

understanding of the area is permissible 

under the Canadian Oceans Act of 1996. 

Regulations regarding this MPA can be 

found on the Department of Justice 

Canada website at: http:// 

laws.justice.gc.ca/en/ShowFullDoc/cr/ 

SOR–2003–87///en. 

The survey will obtain information on 

the sub-seafloor structure of volcanic 

and hydrothermal features that form as 

a result of movements of the Earth’s 

plates; will obtain information on the 

three-dimensional (3–D) seismic 

structure of the crust and top-most 

mantle along an the Endeavour segment; 

and will define the distribution of 

magma beneath active volcanoes. Past 

studies using manned submersibles and 

remotely piloted vehicles have mapped 

the locations and characteristics of vent 

fields along this ridge segment. The 

ETOMO Study will extend that mapping 

beneath the seafloor and allow 

researchers to understand the dynamics 

of these systems. 

Description of the Specified Activity 

The planned survey will involve one 

source vessel, the R/V Marcus 

G.Langseth (Langseth), a seismic 

research vessel owned by the NSF and 

operated by L-DEO. The proposed 

project is scheduled to commence on 

August 17, 2009, and scheduled to end 

on October 13, 2009. The vessel will 

depart Astoria, Oregon on August 17, 

2009 for transit to the Endeavor MPA, 

between 47–48° N. and 128–130° W. 

To obtain high-resolution, 3–D 

structures of the area’s magmatic 

systems and thermal structures, the 

Langseth will deploy a towed array of 

36 airguns. The Langseth will also 

deploy 64 Ocean Bottom Seismometers 

(OBS). As the airgun array is towed 

along the survey lines, the OBSs will 

receive the returning acoustic signals 

and record them internally for later 

analysis. For the ETOMO study, the 

Langseth will not use a hydrophone 

streamer to receive geophysical data 

from the airgun array. 

The ETOMO study (e.g., equipment 

testing, startup, line changes, repeat 

coverage of any areas, and equipment 

recovery) will take place in deep 

(between 1200 and 3000 m, 3,280 feet 

(ft) and 1.8 mi) water and will require 

approximately 10 days to complete 12 

transects of variable lengths totaling 

1800 km of survey lines. Data 

acquisition will include approximately 

240 hours of airgun operation. Please 

see L-DEO’s application for more 

detailed information. The exact dates of 

the activities will depend on logistics, 

weather conditions, and the need to 

repeat some lines if data quality is 

substandard. 

Vessel Specifications 

The Langseth is a seismic research 

vessel with a propulsion system 

designed to be as quiet as possible to 

avoid interference with the seismic 

signals. The vessel, which has a length 

of 71.5 m (235 feet (ft); a beam of 17.0 

m (56 ft); a maximum draft of 5.9 m (19 

ft); and a gross tonnage of 2925, can 

accommodate up to 55 people. The ship 

is powered by two Bergen BRG–6 diesel 

engines, each producing 3550 

horsepower (hp), which drive the two 

propellers directly. Each propeller has 

four blades, and the shaft typically 

rotates at 750 revolutions per minute. 

The vessel also has an 800 hp 

bowthruster, which is not used during 

seismic acquisition. The operation 

speed during seismic acquisition is 

typically 7.4B9.3 km/hour (h) (4–5 

knots). When not towing seismic survey 

gear, the Langseth can cruise at 20B24 

km/h (11–13 knots). The Langseth has a 

range of 25,000 km (13,499 nautical 

miles). The Langseth will also serve as 

the platform from which vessel-based 

marine mammal (and sea turtle) 

observers will watch for animals before 

and during airgun operations. 

Acoustic Source Specifications 

Seismic Airguns 

The full airgun array for the survey 

consists of 36 airguns (a mixture of Bolt 

1500LL and Bolt 1900LLX airguns 

ranging in size from 40 to 360 cubic 

inches (in3)), with a total volume of 

approximately 6,600 in3 and a firing 

pressure of 1900 pounds per square inch 

(psi). The dominant frequency 

components range from two to 188 

Hertz (Hz). 

The array configuration consists of 

four identical linear arrays or strings, 

with 10 airguns on each string; the first 

and last airguns will be spaced 16 m (52 

ft) apart. For each operating string, nine 

airguns will be fired simultaneously, 

whereas the tenth is kept in reserve as 

a spare, to be turned on in case of failure 

of another airgun. The four airgun 

strings will be distributed across an 

approximate area of 24H16 m (79 x 52 

ft) behind the Langseth and will be 

towed approximately 50 to 100 m (164– 

328 ft) behind the vessel at a tow-depth 

of 15 m (49.2 ft). The airgun array will 

fire every 250 m (105 seconds (s)) or 500 

m (210 s) depending on which grid or 

line the Langseth surveys. During firing, 

a brief (approximately 0.1 s) pulse of 

sound is emitted. The airguns will be 

silent during the intervening periods. 

Multibeam Echosounder 

The Langseth will operate a Simrad 

EM120 multibeam echosounder (MBES) 

simultaneously during airgun 

operations to map characteristics of the 

ocean floor. The hull-mounted MBES 

emits brief pulses of mid- or highfrequency (11.25–12.6 kHz) sound in a 

fanshaped beam that extends downward 

and to the sides of the ship. The 

beamwidth is 1 degree (°) fore-aft and 

150° athwartship. The maximum source 

level is 242 dB re 1 μPa• m (root mean 

square (rms)). For deep-water operation, 

each Aping@ consists of nine successive 

fan-shaped transmissions, each 15 

millisecond (ms) in duration and each 

ensonifying a sector that extends 1° 

foreBaft. The nine successive 


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Federal Register / Vol. 74, No. 88 / Friday, May 8, 2009 / Notices 21633 

transmissions span an overall crosstrack angular extent of about 150°, with 

16 ms gaps between the pulses for 

successive sectors. A receiver in the 

overlap area between two sectors would 

receive two 15–ms pulses separated by 

a 16–ms gap. In shallower water, the 

pulse duration is reduced to 5 or 2 ms, 

and the number of transmit beams is 

also reduced. The ping interval varies 

with water depth, from approximately 5 

s at 1000 m (3,281 ft) to 20 s at 4000 m 

(13,124 ft). 

Sub-bottom Profiler 

The Langseth will operate a subbottom profiler (SBP) continuously 

throughout the cruise with the MBES. 

An SBP operates at mid- to high 

frequencies and is generally used 

simultaneously with an MBES to 

provide information about the 

sedimentary features and bottom 

topography. SBP pulses are directed 

downward at typical frequencies of 

approximately 3 18 kHz. However, the 

dominant frequency component of the 

SBP is 3.5 kHz which is directed 

downward in a narrow beam by a hullmounted transducer on the vessel. The 

SBP output varies with water depth 

from 50 watts in shallow water to 800 

watts in deep water and has a normal 

source output (downward) of 200 dB re 

1 μPa m and a maximum source level 

output (downward) of 204 dB re 1 μPa 

m. 

The SBP used aboard the Langseth 

uses seven beams simultaneously, with 

a beam spacing of up to 15° and a fan 

width up to 30°. Pulse duration is 0.4 

100 ms at intervals of 1 s; a common 

mode of operation is to broadcast five 

pulses at 1–s intervals followed by a 5– 

s pause. 

Characteristics of Airgun Pulses 

Discussion of the characteristics of 

airgun pulses has been provided in 

Appendix B of L-DEO=s application and 

in previous Federal Register notices 

(see 69 FR 31792, June 7, 2004; 71 FR 

58790, October 5, 2006; 72 FR 71625, 

December 18, 2007; 73 FR 52950, 

September 12, 2008, or 73 FR 71606, 

November 25, 2008). Reviewers are 

referred to those documents for 

additional information. 

Safety Radii 

Safety zones are areas defined by the 

radius of received sound levels believed 

to have the potential for at least 

temporary hearing impairment (HESS, 

1999). The distance from the sound 

source at which an animal would be 

exposed to these different received 

sound levels may be estimated and is 

typically referred to as safety radii. 

These safety radii are specifically used 

to help NMFS estimate the number of 

marine mammals likely to be harassed 

by the proposed activity and in deciding 

how close a marine mammal may 

approach an operating sound source 

before the applicant will be required to 

power-down or shut down the sound 

source. 

During this study, all survey efforts 

will take place in deep (greater than 

1000 m, 3820 ft) water. L-DEO has 

summarized the modeled safety radii for 

the planned airgun configuration in 

Table 1 which shows the predicted 

distances at which sound levels (190 

decibels (dB), 180 dB, and 160 dB) are 

expected to be received from the 36– 

airgun array and a single airgun 

operating in water greater than 1000 m 

(3,820 ft) in depth. 

TABLE 1. PREDICTED DISTANCES TO WHICH SOUND LEVELS ≥190, 180, AND 160 DB RE 1 μPA MIGHT BE RECEIVED IN

DEEP (>1000 M; 3280 FT) WATER FROM THE 36–AIRGUN ARRAY DURING THE SEISMIC SURVEY, AUGUST SEPTEMBER, 

2009 (BASED ON L-DEO MODELING). 

Source and Volume Tow Depth (m) 

Predicted RMS Distances (m) 

190 dB 180 dB 160 dB 

Single Bolt airgun 40 in3 6–15* 12 40 385 

4 strings 36 airguns 6600 in3 6 220 710 4670 

9 300 950 6000 

12 340 1120 6850 

15 380 1220 7690 

*

The tow depth has minimal effect on the maximum near-field output and the shape of the frequency spectrum for the single 40 in3 airgun; 

thus the predicted safety radii are essentially the same at each tow depth. 

The L-DEO model applied to airgun 

configuration does not allow for bottom 

interactions, and thus is most directly 

applicable to deep water and to 

relatively short ranges. The calculated 

distances are expected to overestimate 

the actual distances to the 

corresponding Sound Pressure Levels 

(SPL), given the deep-water results of 

Tolstoy et al. (2004a,b). Additional 

information regarding how the safety 

radii were calculated and how the 

empirical measurements were used to 

correct the modeled numbers may be 

found in Appendix A of L-DEO=s 

Environmental Assessment (EA). The 

conclusion that the model predictions 

in Table 1 are precautionary, relative to 

actual 180- and 190–dB (rms) radii, is 

based on empirical data from the 

acoustic calibration of different airgun 

configurations used by the R/V Maurice 

Ewing (Ewing) in the northern Gulf of 

Mexico. (Tolstoy et al., 2004a,b). 

L-DEO conducted a more extensive 

acoustic calibration study of the 

Langseth=s 36–airgun array in late 

2007/early 2008 in the northern Gulf of 

Mexico (LGL Ltd., 2006; Holst and 

Beland, 2008). L-DEO is currently 

modeling the distances to the 

corresponding Sound Pressure Levels 

(SPL) (e.g., 190, 180, and 160 dB re 1 

μPa (rms)) for various airgun 

configurations and water depths. Those 

results are not yet available. However, 

the empirical data from the 2007/2008 

calibration study will be used to refine 

the exclusion zones proposed above for 

use during survey, if the data are 

appropriate and available at the time of 

the survey. 

Description of Marine Mammals in the 

Activity Area 

Thirty-three marine mammal species 

may occur off the coast of British 

Columbia, Canada, including 20 

odontocetes (toothed cetaceans), 7 

mysticetes (baleen whales), 5 pinnipeds, 

and the sea otter (Enhydra sp.). In the 

United States, sea otters are managed by 

the U.S. Fish and Wildlife Service 

(USFWS) and are unlikely to be 

encountered in or near the Endeavor 

Marine Protected Area where seismic 

operations will occur, and are, therefore, 

not addressed further in this document. 

Eight of these species are listed as 

endangered under the U.S. Endangered 

Species Act of 1973 (ESA), including 

the Steller sea lion (Eumetopias 

jubatus), the humpback (Megaptera 


hsrobinson on PROD1PC76 with NOTICES
21634 Federal Register / Vol. 74, No. 88 / Friday, May 8, 2009 / Notices 

novaeanliae), sei (Balaenoptera 

borealis), fin (Balenoptera physalus), 

blue (Balenoptera musculus), North 

Pacific right (Eubalena japonica), sperm 

(Physeter macrocephalus), and Southern 

Resident killer (Orcinus orca) whales. 

This proposed IHA will only address 

requested take authorizations for 

cetaceans and pinnipeds. Table 2 below 

outlines the species, their habitat and 

abundance in the proposed survey area, 

the estimated number of exposures 

(based on average density) to sound 

levels greater than or equal to 160 dB 

during the seismic survey if no animals 

moved away from the survey vessel. 

Species Habitat Abundance in the 

NE Pacific 

Occurrence in the 

Survey Area 

Estimated 

Number of Exposures to 

Sound Levels ≥ 

160 dB 

Estimated 

Number of Individuals Exposed to 

Sound Levels 

≥160 dB 

Approx. Percent of Regional Population 

North Pacific right 

whale* 

Coastal and shelf waters 100–200 Rare and unlikely 0 0 0 

Humpback whale* Coastal waters >6000 Uncommon 29 6 0.10 

Minke whale Coastal and shelf waters 9000 Uncommon 26 26 0.06 

Sei whale Pelagic 7260 - 12,620 Uncommon 5 1 0.01 

Fin whale* Pelagic, shelf and 

coastal waters 

13,620–18,680 Uncommon 39 8 0.05 

Blue whale* Pelagic, shelf and 

inshore waters 

1186 Uncommon 8 2 0.14 

Sperm whale* Pelagic 24,000 Uncommon 52 10 0.04 

Pygmy sperm whale Deep waters off the 

shelf 

Not available Common 47 9 Not available 

Dwarf Sperm whale Deep waters off the 

shelf 

Not available Uncommon 0 0 0.0 

Baird’s beaked 

whale 

Deep waters and 

cont. slopes 

6000 Common 62 13 0.21 

Blainville’s beaked 

whale 

Deep waters and 

cont. slopes 

603 Uncommon 8 2 0.28 

Cuvier’s beaked 

whale 

Pelagic 20,000 Uncommon 0 0 0.0 

Hubb’s beaked 

whale 

Deep waters and 

cont. slopes 

421 Uncommon 8 2 0.40 

Stejneger’s beaked 

whale 

Deep waters 421 Uncommon 8 2 0.40 

Bottlenose dolphin Coastal and offshore 

waters 

3257 Rare 0 0 0.0 

Striped dolphin Pelagic 23,883 rare 2 0 0.0 

Short-beaked common dolphin Coastal and offshore 

waters 

487,622 Common 511 104 0.02 

Pacific white-sided 

dolphin 

Pelagic, shelf and 

slope waters 

931,000 Common 895 181 0.02 

Northern right-whale 

dolphin 

Pelagic, shelf and 

slope waters 

15,305 Common 699 142 0.93 

Risso’s dolphin Pelagic 12,093 Common 467 95 0.78 

False killer whale Pelagic Not available Rare 0 0 0.0 

Killer whale Widely distributed 8500 Uncommon 61 12 0.15 

Short-finned pilot 

whale 

Pelagic 160,200 Uncommon 0 0 00.0 


hsrobinson on PROD1PC76 with NOTICES
Federal Register / Vol. 74, No. 88 / Friday, May 8, 2009 / Notices 21635 

Species Habitat Abundance in the 

NE Pacific 

Occurrence in the 

Survey Area 

Estimated 

Number of Exposures to 

Sound Levels ≥ 

160 dB 

Estimated 

Number of Individuals Exposed to 

Sound Levels 

≥160 dB 

Approx. Percent of Regional Population 

Dall’s porpoise Offshore and nearshore waters 57,549 Common 5337 1081 1.88 

Northern fur seal Coastal 721,935 Common 360 73 0.01 

Total 8,624 1,748 

Table 2. Abundance, preferred habitat, and commonness of the marine mammal species that may be encountered during the proposed survey 

within the ETOMO survey area. The far right columns indicate the estimated number of each species that will be exposed to ≥160 dB based on 

average density estimates. NMFS believes that, when mitigation measures are taken into consideration, the activity is likely to result in take of 

numbers of animals less than those indicated by the column titled NUmber of Individuals Exposed ≥160 dB. 

* Federally listed endangered species. 

Detailed information regarding the 

status and distribution of these marine 

mammals may be found in sections III 

and IV of L-DEO’s application. 

Potential Effects of the Proposed 

Activity on Marine Mammals 

Summary of Potential Effects of Airgun 

Sounds on Marine Mammals 

The effects of sounds from airguns 

might include one or more of the 

following: tolerance, masking of natural 

sounds, behavioral disturbance, 

temporary or permanent hearing 

impairment, or non-auditory physical or 

physiological effects (Richardson et al., 

1995; Gordon et al., 2004; Nowacek et 

al., 2007; Southall et al., 2007). 

Permanent hearing impairment, in the 

unlikely event that it occurred, would 

constitute injury, but temporary 

threshold shift (TTS) is not an injury 

(Southall et al., 2007). Although the 

possibility cannot be entirely excluded, 

it is unlikely that the project would 

result in any cases of temporary or 

permanent hearing impairment, or any 

significant non-auditory physical or 

physiological effects. Some behavioral 

disturbance is expected, but is expected 

to be localized and short-term. 

Tolerance 

Numerous studies have shown that 

pulsed sounds from airguns are often 

readily detectable in the water at 

distances of many kilometers. For a brief 

summary of the characteristics of airgun 

pulses, see Appendix B of L-DEO’s 

application. Several studies have also 

shown that marine mammals at 

distances more than a few kilometers 

from operating seismic vessels often 

show no apparent response (tolerance) 

(see Appendix B (5) of L-DEO’s EA). 

That is often true even in cases when 

the pulsed sounds must be readily 

audible to the animals based on 

measured received levels and the 

hearing sensitivity of that mammal 

group. Although various baleen whales, 

toothed whales, and (less frequently) 

pinnipeds have been shown to react 

behaviorally to airgun pulses under 

some conditions, at other times 

mammals of all three types have shown 

no overt reactions. In general, pinnipeds 

usually seem to be more tolerant of 

exposure to airgun pulses than 

cetaceans, with the relative 

responsiveness of baleen and toothed 

whales being variable. 

Masking 

Introduced underwater sound may, 

through masking, reduce the effective 

communication distance of a marine 

mammal species if the frequency of the 

source is close to that used as a signal 

by the marine mammal, and if the 

anthropogenic sound is present for a 

significant fraction of the time 

(Richardson et al., 1995). 

Masking effects of pulsed sounds 

(even from large arrays of airguns) on 

marine mammal calls and other natural 

sounds are expected to be limited, 

although there are very few specific data 

on this. Because of the intermittent 

nature and low duty cycle of seismic 

pulses, animals can emit and receive 

sounds in the relatively quiet intervals 

between pulses. However, in some 

situations, multi-path arrivals and 

reverberation cause airgun sound to 

arrive for much or all of the interval 

between pulses (e.g., Simard et al., 

2005; Clark and Gagnon, 2006) which 

could mask calls. Some baleen and 

toothed whales are known to continue 

calling in the presence of seismic 

pulses, and their calls can usually be 

heard between the seismic pulses (e.g., 

Richardson et al., 1986; McDonald et al., 

1995; Greene et al., 1999; Nieukirk et 

al., 2004; Smultea et al., 2004; Holst et 

al., 2005a,b, 2006). In the northeast 

Pacific Ocean, blue whale calls have 

been recorded during a seismic survey 

off Oregon (McDonald et al., 1995). 

Among odontocetes, there has been one 

report that sperm whales ceased calling 

when exposed to pulses from a very 

distant seismic ship (Bowles et al., 

1994). However, more recent studies 

found that this species continued 

calling in the presence of seismic pulses 

(Madsen et al., 2002; Tyack et al., 2003; 

Smultea et al., 2004; Holst et al., 2006; 

Jochens et al., 2006, 2008). Dolphins 

and porpoises commonly are heard 

calling while airguns are operating (e.g., 

Gordon et al., 2004; Smultea et al., 2004; 

Holst et al., 2005a,b; Potter et al., 2007). 

The sounds important to small 

odontocetes are predominantly at much 

higher frequencies than are the 

dominant components of airgun sounds, 

thus limiting the potential for masking. 

In general, masking effects of seismic 

pulses are expected to be negligible, 

given the normally intermittent nature 

of seismic pulses. Masking effects on 

marine mammals are discussed further 

in Appendix B (4) of L-DEO’s EA. 

Disturbance Reactions 

Disturbance includes a variety of 

effects, including subtle to conspicuous 

changes in behavior, movement, and 

displacement. Based on NMFS (2001, p. 

9293), NRC (2005), and Southall et al. 

(2007), L-DEO assumes that simple 

exposure to sound, or brief reactions 

that do not disrupt behavioral patterns 

in a potentially significant manner, do 

not constitute harassment or ‘‘taking’’. 

By potentially significant, L-DEO means 

‘‘in a manner that might have 

deleterious effects to the well-being of 

individual marine mammals or their 

populations’’. 

Reactions to sound, if any, depend on 

species, state of maturity, experience, 

current activity, reproductive state, time 

of day, and many other factors 

(Richardson et al., 1995; Wartzok et al., 

2004; Southall et al., 2007). If a marine 

mammal does react briefly to an 


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underwater sound by changing its 

behavior or moving a small distance, the 

impacts of the change are unlikely to be 

significant to the individual, let alone 

the stock or population. However, if a 

sound source displaces marine 

mammals from an important feeding or 

breeding area for a prolonged period, 

impacts on individuals and populations 

could be significant (e.g., Lusseau and 

Bejder, 2007; Weilgart, 2007). Given the 

many uncertainties in predicting the 

quantity and types of impacts of noise 

on marine mammals, it is common 

practice to estimate how many 

mammals would be present within a 

particular distance of industrial 

activities and exposed to a particular 

level of industrial sound. In most cases, 

this approach likely overestimates the 

numbers of marine mammals that would 

be affected in some biologicallyimportant manner. 

The sound criteria used to estimate 

how many marine mammals might be 

disturbed to some biologicallyimportant degree by a seismic program 

are based primarily on behavioral 

observations of a few species. Detailed 

studies have been done on humpback, 

gray (Eshrichtius robustus), bowhead 

(Balena mysticetes), and sperm whales, 

and on ringed seals (Pusa hispida). Less 

detailed data are available for some 

other species of baleen whales, and 

small toothed whales, but for many 

species there are no data on responses 

to marine seismic surveys. 

Baleen Whales 

Baleen whales generally tend to avoid 

operating airguns, but avoidance radii 

are quite variable. Whales are often 

reported to show no overt reactions to 

pulses from large arrays of airguns at 

distances beyond a few kilometers, even 

though the airgun pulses remain well 

above ambient noise levels out to much 

longer distances. However, as reviewed 

in Appendix B (5) of L-DEO’s EA, 

baleen whales exposed to strong noise 

pulses from airguns often react by 

deviating from their normal migration 

route and/or interrupting their feeding 

and moving away. In the cases of 

migrating gray and bowhead whales, the 

observed changes in behavior appeared 

to be of little or no biological 

consequence to the animals. They 

simply avoided the sound source by 

displacing their migration route to 

varying degrees, but within the natural 

boundaries of the migration corridors. 

Studies of gray, bowhead, and 

humpback whales have shown that 

seismic pulses with received levels of 

160 170 dB re 1 μPa (rms) seem to cause 

obvious avoidance behavior in a 

substantial fraction of the animals 

exposed (Richardson et al., 1995). In 

many areas, seismic pulses from large 

arrays of airguns diminish to those 

levels at distances ranging from 4–15 

km (2.5–9.3 mi) from the source. A 

substantial proportion of the baleen 

whales within those distances may 

show avoidance or other strong 

behavioral reactions to the airgun array. 

Subtle behavioral changes sometimes 

become evident at somewhat lower 

received levels, and studies summarized 

in Appendix B of L-DEO’s EA have 

shown that some species of baleen 

whales, notably bowhead and 

humpback whales, at times show strong 

avoidance at received levels lower than 

160 170 dB re 1 μPa (rms). 

Responses of humpback whales to 

seismic surveys have been studied 

during migration, on summer feeding 

grounds, and on Angolan winter 

breeding grounds; there has also been 

discussion of effects on the Brazilian 

wintering grounds. McCauley et al. 

(1998, 2000a) studied the responses of 

humpback whales off Western Australia 

to a full-scale seismic survey with a 16– 

airgun, 2678–in3 array, and to a single 

20–in3 airgun with source level of 227 

dB re 1 μPa m (peak to peak). McCauley 

et al. (1998) documented that avoidance 

reactions began at 5–8 km (3–5 mi) from 

the array, and that those reactions kept 

most pods approximately 3–4 km (1.8– 

2.5 mi) from the operating seismic boat. 

McCauley et al. (2000a) noted localized 

displacement during migration of 4–5 

km (2.5–3.1 mi) by traveling pods and 

7–12 km (4.3–7.5 mi) by more sensitive 

resting pods of cow-calf pairs. 

Avoidance distances with respect to the 

single airgun were smaller but 

consistent with the results from the full 

array in terms of the received sound 

levels. The mean received level for 

initial avoidance of an approaching 

airgun was 140 dB re 1 μPa (rms) for 

humpback pods containing females, and 

at the mean closest point of approach 

distance the received level was 143 dB 

re 1 μPa (rms). The initial avoidance 

response generally occurred at distances 

of 5–8 km (3.1–4.9 mi) from the airgun 

array and 2 km (1.2 mi) from the single 

airgun. However, some individual 

humpback whales, especially males, 

approached within distances of 100–400 

m (328–1312 ft), where the maximum 

received level was 179 dB re 1 μPa 

(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–in3) airgun (Malme et al., 1985). 

Malme et al. reported that some of the 

humpbacks seemed startled at received 

levels of 150 169 dB re 1 μPa and 

concluded that there was no clear 

evidence of avoidance, despite the 

possibility of subtle effects, at received 

levels up to 172 re 1 FPa on an 

approximate rms basis. 

It has been suggested that South 

Atlantic humpback whales wintering off 

Brazil may be displaced or even strand 

upon exposure to seismic surveys (Engel 

et al., 2004). The evidence for this was 

circumstantial and subject to alternative 

explanations (IAGC, 2004). Also, the 

evidence was not consistent with 

subsequent results from the same area of 

Brazil (Parente et al., 2006), or with 

direct studies of humpbacks exposed to 

seismic surveys in other areas and 

seasons. After allowance for data from 

subsequent years, there was ‘‘no 

observable direct correlation’’ between 

strandings and seismic surveys (IWC, 

2007:236). 

There are no data on reactions of right 

whales to seismic surveys, but results 

from the closely-related bowhead whale 

show that their responsiveness can be 

quite variable depending on their 

activity (migrating vs. feeding). 

Bowhead whales migrating west across 

the Alaskan Beaufort Sea in autumn, in 

particular, are unusually responsive, 

with substantial avoidance occurring 

out to distances of 20 - 30 km (12.4 - 

18.6 mi) from a medium-sized airgun 

source at received sound levels of 

around 120 130 dB re 1 μPa (rms) 

(Miller et al., 1999; Richardson et al., 

1999; see Appendix B (5) of the EA. 

However, more recent research on 

bowhead whales (Miller et al., 2005; 

Harris et al., 2007) corroborates earlier 

evidence that, during the summer 

feeding season, bowheads are not as 

sensitive to seismic sources. 

Nonetheless, subtle but statistically 

significant changes in surfacing 

respiration dive cycles were evident 

upon statistical analysis (Richardson et 

al., 1986). In summer, bowheads 

typically begin to show avoidance 

reactions at received levels of about 152 

178 dB re 1 μPa (rms) (Richardson et al., 

1986, 1995; Ljungblad et al., 1988; 

Miller et al., 2005). 

Reactions of migrating and feeding 

(but not wintering) gray whales to 

seismic surveys have been studied. 

Malme et al. (1986, 1988) studied the 

responses of feeding eastern Pacific gray 

whales to pulses from a single 100–in3

airgun off St. Lawrence Island in the 

northern Bering Sea. They estimated, 

based on small sample sizes, that 50 

percent of feeding gray whales stopped 

feeding at an average received pressure 

level of 173 dB re 1 μPa on an 

(approximate) rms basis, and that 10 

percent of feeding whales interrupted 

feeding at received levels of 163 dB re 


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1 μPa (rms). Those findings were 

generally consistent with the results of 

experiments conducted on larger 

numbers of gray whales that were 

migrating along the California coast 

(Malme et al., 1984; Malme and Miles, 

1985), and western Pacific gray whales 

feeding off Sakhalin Island, Russia 

(Wursig et al., 1999; Gailey et al., 2007; 

Johnson et al., 2007; Yazvenko et al., 

2007a,b), along with data on gray 

whales off British Columbia (Bain and 

Williams, 2006). 

Various species of Balaenoptera (blue, 

sei, fin, and minke whales) have 

occasionally been reported in areas 

ensonified by airgun pulses (Stone, 

2003; MacLean and Haley, 2004; Stone 

and Tasker, 2006). Sightings by 

observers on seismic vessels off the 

United Kingdom from 1997 to 2000 

suggest that, during times of good 

sightability, sighting rates for mysticetes 

(mainly fin and sei whales) were similar 

when large arrays of airguns were 

shooting vs. silent (Stone, 2003; Stone 

and Tasker, 2006). However, these 

whales tended to exhibit localized 

avoidance, remaining significantly 

further (on average) from the airgun 

array during seismic operations 

compared with non-seismic periods 

(Stone and Tasker, 2006). In a study off 

Nova Scotia, Moulton and Miller (2005) 

found little difference in sighting rates 

(after accounting for water depth) and 

initial sighting distances of 

balaenopterid whales when airguns 

were operating versus silent. However, 

there were indications that these whales 

were more likely to be moving away 

when seen during airgun operations. 

Similarly, ship-based monitoring 

studies of blue, fin, sei and minke 

whales offshore of Newfoundland 

(Orphan Basin and Laurentian Subbasin) found no more than small 

differences in sighting rates and swim 

directions during seismic vs. nonseismic periods Moulton et al., 2005, 

2006a,b). 

Data on short-term reactions by 

cetaceans to impulsive noises are not 

necessarily indicative of long-term or 

biologically significant effects. It is not 

known whether impulsive sounds affect 

reproductive rate or distribution and 

habitat use in subsequent days or years. 

However, gray whales have continued to 

migrate annually along the west coast of 

North America with substantial 

increases in the population over recent 

years, despite intermittent seismic 

exploration (and much ship traffic) in 

that area for decades (Appendix A in 

Malme et al., 1984; Richardson et al., 

1995; Angliss and Outlaw, 2008). The 

western Pacific gray whale population 

did not seem affected by a seismic 

survey in its feeding ground during a 

previous year (Johnson et al., 2007). 

Similarly, bowhead whales have 

continued to travel to the eastern 

Beaufort Sea each summer, and their 

numbers have increased notably, 

despite seismic exploration in their 

summer and autumn range for many 

years (Richardson et al., 1987; Angliss 

and Outlaw, 2008). 

Toothed Whales 

Little systematic information is 

available about reactions of toothed 

whales to noise pulses. Few studies 

similar to the more extensive baleen 

whale/seismic pulse work summarized 

above and (in more detail) in Appendix 

B of L-DEO’s EA have been reported for 

toothed whales. However, there are 

recent systematic studies on sperm 

whales (Jochens et al., 2006; Miller et 

al., 2006), and there is an increasing 

amount of information about responses 

of various odontocetes to seismic 

surveys based on monitoring studies 

(e.g., Stone, 2003; Smultea et al., 2004; 

Moulton and Miller, 2005; Bain and 

Williams, 2006; Holst et al., 2006; Stone 

and Tasker, 2006; Potter et al., 2007; 

Weir, 2008). 

Seismic operators and marine 

mammal observers on seismic vessels 

regularly see dolphins and other small 

toothed whales near operating airgun 

arrays, but in general there is a tendency 

for most delphinids to show some 

avoidance of operating seismic vessels 

(e.g., Goold, 1996a,b,c; Calambokidis 

and Osmek, 1998; Stone, 2003; Moulton 

and Miller, 2005; Holst et al., 2006; 

Stone and Tasker, 2006; Weir, 2008). 

Some dolphins seem to be attracted to 

the seismic vessel and floats, and some 

ride the bow wave of the seismic vessel 

even when large arrays of airguns are 

firing (e.g., Moulton and Miller, 2005). 

Nonetheless, small toothed whales more 

often tend to head away, or to maintain 

a somewhat greater distance from the 

vessel, when a large array of airguns is 

operating than when it is silent (e.g., 

Stone and Tasker, 2006; Weir, 2008). In 

most cases the avoidance radii for 

delphinids appear to be small, on the 

order of 1 km less, and some individuals 

show no apparent avoidance. The 

beluga (Delphinapterus leucas) is a 

species that (at times) shows longdistance avoidance of seismic vessels. 

Aerial surveys conducted in the 

southeastern Beaufort Sea during 

summer found that sighting rates of 

beluga whales were significantly lower 

at distances 10–20 km (6.2–12.4 mi) 

compared with 20–30 km (12.4–18.6 mi) 

from an operating airgun array, and 

observers on seismic boats in that area 

rarely see belugas (Miller et al., 2005; 

Harris et al., 2007). 

Captive bottlenose dolphins (Tursiops 

truncates) and beluga whales exhibited 

changes in behavior when exposed to 

strong pulsed sounds similar in 

duration to those typically used in 

seismic surveys (Finneran et al., 2000, 

2002, 2005). However, the animals 

tolerated high received levels of sound 

before exhibiting aversive behaviors. 

Results for porpoises depend on 

species. The limited available data 

suggest that harbor porpoises (Phocoena 

phocoena) show stronger avoidance of 

seismic operations than do Dall’s 

porpoises (Phocoenoides dalli) (Stone, 

2003; MacLean and Koski, 2005; Bain 

and Williams, 2006; Stone and Tasker, 

2006). Dall’s porpoises seem relatively 

tolerant of airgun operations (MacLean 

and Koski, 2005; Bain and Williams, 

2006), although they too have been 

observed to avoid large arrays of 

operating airguns (Calambokidis and 

Osmek, 1998; Bain and Williams, 2006). 

This apparent difference in 

responsiveness of these two porpoise 

species is consistent with their relative 

responsiveness to boat traffic and some 

other acoustic sources (Richardson et 

al., 1995; Southall et al., 2007). 

Most studies of sperm whales exposed 

to airgun sounds indicate that the sperm 

whale shows considerable tolerance of 

airgun pulses (e.g., Stone, 2003; 

Moulton et al., 2005, 2006a; Stone and 

Tasker, 2006; Weir, 2008). In most cases 

the whales do not show strong 

avoidance, and they continue to call 

(see Appendix B of L-DEO’s EA for 

review). However, controlled exposure 

experiments in the Gulf of Mexico 

indicate that foraging behavior was 

altered upon exposure to airgun sound 

(Jochens et al., 2006). In the Sperm 

Whale Seismic Study (SWSS), D-tags 

(Johnson and Tyack, 2003) were used to 

record the movement and acoustic 

exposure of eight foraging sperm whales 

before, during, and after controlled 

sound exposures of airgun arrays in the 

Gulf of Mexico (Jochens et al., 2008). 

Whales were exposed to maximum 

received sound levels between 111 and 

147 dB re 1 μPa rms (131 – 164 dB re 

1 μPa pk-pk) at ranges of approximately 

1.4 - 12.6 km (0.8 – 7.8 mi) from the 

sound source. Although the tagged 

whales showed no horizontal 

avoidance, some whales changed 

foraging behavior during full-array 

exposure (Jochens et al., 2008). 

There are almost no specific data on 

the behavioral reactions of beaked 

whales to seismic surveys. However, 

northern bottlenose whales continued to 

produce high-frequency clicks when 

exposed to sound pulses from distant 


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seismic surveys (Laurinolli and 

Cochrane, 2005; Simard et al., 2005). 

Most beaked whales tend to avoid 

approaching vessels of other types (e.g., 

Wursig et al., 1998). They may also dive 

for an extended period when 

approached by a vessel (e.g., Kasuya, 

1986), although it is uncertain how 

much longer such dives may be as 

compared to dives by undisturbed 

beaked whales, which also are often 

quite long (Baird et al., 2006; Tyack et 

al., 2006). In any event, it is likely that 

most beaked whales would also show 

strong avoidance of an approaching 

seismic vessel, although this has not 

been documented explicitly. 

There are increasing indications that 

some beaked whales tend to strand 

when naval exercises involving midfrequency sonar operation are ongoing 

nearby (e.g., Simmonds and LopezJurado, 1991; Frantzis, 1998; NOAA and 

USN, 2001; Jepson et al., 2003; 

Hildebrand, 2005; Barlow and Gisiner, 

2006; see also the ‘‘Strandings and 

Mortality’’ subsection, later). These 

strandings are apparently at least in part 

a disturbance response, although 

auditory or other injuries or other 

physiological effects may also be 

involved. Whether beaked whales 

would ever react similarly to seismic 

surveys is unknown (see ‘‘Strandings 

and Mortality’’, below). Seismic survey 

sounds are quite different from those of 

the sonars in operation during the 

above-cited incidents, and in particular, 

the dominant frequencies in airgun 

pulses are at lower frequencies than 

used by mid-frequency naval sonars. 

Odontocete reactions to large arrays of 

airguns are variable and, at least for 

delphinids and some porpoises (e.g., 

Dall’s, Phocoenoides dalli), seem to be 

confined to a smaller radius than has 

been observed for the more responsive 

of the mysticetes, belugas, and harbor 

porpoises (refer to Appendix B in LDEO’s EA). 

Pinnipeds 

Pinnipeds are not likely to show a 

strong avoidance reaction to the airgun 

array. Visual monitoring from seismic 

vessels has shown only slight (if any) 

avoidance of airguns by pinnipeds, and 

only slight (if any) changes in behavior 

see Appendix B (5) of the EA. In the 

Beaufort Sea, some ringed seals avoided 

an area of 100 m (328 ft) to (at most) a 

few hundred meters around seismic 

vessels, but many seals remained within 

100 - 200 m (328 656 ft) of the trackline 

as the operating airgun array passed by 

(e.g., Harris et al., 2001; Moulton and 

Lawson 2002; Miller et al., 2005). 

Ringed seal sightings averaged 

somewhat farther away from the seismic 

vessel when the airguns were operating 

than when they were not, but the 

difference was small (Moulton and 

Lawson, 2002). Similarly, in Puget 

Sound, sighting distances for harbor 

seals (Phoca vitulina) and California sea 

lions (Zalophus californianus) tended to 

be larger when airguns were operating 

(Calambokidis and Osmek, 1998). 

Previous telemetry work suggests that 

avoidance and other behavioral 

reactions may be stronger than evident 

to date from visual studies (Thompson 

et al., 1998). Even if reactions of any 

pinnipeds that might be encountered in 

the present study area are as strong as 

those evident in the telemetry study, 

reactions are expected to be confined to 

relatively small distances and durations, 

with no long-term effects on pinniped 

individuals or populations. 

Hearing Impairment and Other Physical 

Effects 

Temporary or permanent hearing 

impairment is a possibility when marine 

mammals are exposed to very strong 

sounds, and temporary threshold shift 

(TTS) has been demonstrated and 

studied in certain captive odontocetes 

and pinnipeds exposed to strong sounds 

(reviewed in Southall et al., 2007). 

Current NMFS policy regarding 

exposure of marine mammals to highlevel sounds is that cetaceans and 

pinnipeds should not be exposed to 

impulsive sounds with received levels 

greater than or equal to 180 and 190 dB 

re 1 μPa rms, respectively (NMFS 2000). 

L-DEO has used those criteria to 

establish the exclusion (i.e., shut-down) 

zones planned for the proposed seismic 

survey. However, those criteria were 

established before there was any 

information about minimum received 

levels of sounds necessary to cause 

auditory impairment in marine 

mammals. As discussed in Appendix B 

of the EA: (1) the 180–dB criterion for 

cetaceans is probably quite 

precautionary, i.e., lower than necessary 

to avoid temporary auditory impairment 

let alone permanent auditory injury; (2) 

NMFS treats TTS as the upper bound of 

Level B Harassment. Tissues are not 

irreparably damaged with the onset of 

TTS, the effects are temporary 

(particularly for onset-TTS), and NMFS 

does not believe that this effect qualifies 

as an injury; (3) the minimum sound 

level necessary to cause permanent 

hearing impairment (‘‘Level A 

harassment’’) is higher, by a variable 

and generally unknown amount, than 

the level that induces barely detectable 

TTS; and (4) the level associated with 

the onset of TTS is often considered to 

be a level below which there is no 

danger of permanent damage. The actual 

PTS threshold is likely to be well above 

the level causing onset of TTS (Southall 

et al., 2007). 

Recommendations for new sciencebased noise exposure criteria for marine 

mammals, frequency-weighting 

procedures, and related matters were 

published recently (Southall et al., 

2007). Those recommendations have 

not, as of early 2009, been formally 

adopted by NMFS for use in regulatory 

processes and during mitigation 

programs associated with seismic 

surveys. However, some aspects of the 

recommendations have been taken into 

account in certain Environmental 

Impact Statements and small-take 

authorizations. NMFS has indicated that 

it may issue new noise exposure criteria 

for marine mammals that account for 

the now available scientific data on 

TTS, the expected offset between the 

TTS and PTS thresholds, differences in 

the acoustic frequencies to which 

different marine mammal groups are 

sensitive, and other relevant factors. 

Preliminary information about possible 

changes in the regulatory and mitigation 

requirements, and about the possible 

structure of new criteria, was given by 

Wieting (2004) and NMFS (2005). 

Several aspects of the planned 

monitoring and mitigation measures for 

this project are designed to detect 

marine mammals occurring near the 

airgun array, and to avoid exposing 

them to sound pulses that might, at least 

in theory, cause hearing impairment 

(see section XI of L-DEO’s application). 

In addition, many cetaceans and (to a 

limited degree) pinnipeds and sea 

turtles show some avoidance of the area 

where received levels of airgun sound 

are high enough such that hearing 

impairment could potentially occur. In 

those cases, the avoidance responses of 

the animals themselves will reduce or 

(most likely) avoid any possibility of 

hearing impairment. 

Non-auditory physical effects might 

also occur in marine mammals exposed 

to strong underwater pulsed sound. 

Possible types of non-auditory 

physiological effects or injuries that 

might (in theory) occur in mammals 

close to a strong sound source include 

stress, neurological effects, bubble 

formation, and other types of organ or 

tissue damage. It is possible that some 

marine mammal species (i.e., beaked 

whales) may be especially susceptible to 

injury and/or stranding when exposed 

to strong pulsed sounds. However, as 

discussed below, there is no definitive 

evidence that any of these effects occur 

even for marine mammals in close 

proximity to large arrays of airguns. It is 

unlikely that any effects of these types 

would occur during the proposed 


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project given the brief duration of 

exposure of any given mammal, the 

deep water in the survey area, and the 

planned monitoring and mitigation 

measures (see below). The following 

subsections discuss in somewhat more 

detail the possibilities of TTS, PTS, and 

non-auditory physical effects. 

Temporary Threshold Shift (TTS) 

TTS is the mildest form of hearing 

impairment that can occur during 

exposure to a strong sound (Kryter, 

1985). While experiencing TTS, the 

hearing threshold rises and a sound 

must be stronger in order to be heard. 

In terrestrial mammals, TTS can last 

from minutes or hours to (in cases of 

strong TTS) days. For sound exposures 

at or somewhat above the TTS 

threshold, hearing sensitivity in both 

terrestrial and marine mammals 

recovers rapidly after exposure to the 

noise ends. Few data on sound levels 

and durations necessary to elicit mild 

TTS have been obtained for marine 

mammals, and none of the published 

data concern TTS elicited by exposure 

to multiple pulses of sound. Available 

data on TTS in marine mammals are 

summarized in Southall et al. (2007). 

For toothed whales exposed to single 

short pulses, the TTS threshold appears 

to be, to a first approximation, a 

function of the energy content of the 

pulse (Finneran et al., 2002, 2005). 

Given the available data, the received 

energy level of a single seismic pulse 

(with no frequency weighting) might 

need to be approximately 186 dB re 1 

μPa2•s (i.e., 186 dB SEL or 

approximately 196 201 dB re 1 μPa rms 

in order to produce brief, mild TTS. 

Exposure to several strong seismic 

pulses that each have received levels 

near 190 dB re 1 μPa rms might result 

in cumulative exposure of 

approximately 186 dB SEL and thus 

slight TTS in a small odontocete, 

assuming the TTS threshold is (to a first 

approximation) a function of the total 

received pulse energy. The distances 

from the Langseth’s airguns at which the 

received energy level (per pulse, flatweighted) would be expected to be 

greater than or equal to 190 dB re 1 μPa 

rms are estimated in Table 1. Levels 

greater than or equal to 190 dB re 1 μPa 

rms are expected to be restricted to radii 

no more than 380 m (1246 ft) (See Table 

1). For an odontocete closer to the 

surface, the maximum radius with 

greater than or equal to 190 dB re 1 μPa 

rms would be smaller. 

The above TTS information for 

odontocetes is derived from studies on 

the bottlenose dolphin and beluga. 

There is no published TTS information 

for other types of cetaceans. However, 

preliminary evidence from a harbor 

porpoise exposed to airgun sound 

suggests that its TTS threshold may 

have been lower (Lucke et al., 2007). 

For baleen whales, there are no data, 

direct or indirect, on levels or properties 

of sound that are required to induce 

TTS. The frequencies to which baleen 

whales are most sensitive are assumed 

to be lower than those to which 

odontocetes are most sensitive, and 

natural background noise levels at those 

low frequencies tend to be higher. As a 

result, auditory thresholds of baleen 

whales within their frequency band of 

best hearing are believed to be higher 

(less sensitive) than are those of 

odontocetes at their best frequencies 

(Clark and Ellison, 2004). From this, it 

is suspected that received levels causing 

TTS onset may also be higher in baleen 

whales (Southall et al., 2007). In any 

event, no cases of TTS are expected 

given three considerations: (1) the low 

abundance of baleen whales in most 

parts of the planned study area; (2) the 

strong likelihood that baleen whales 

would avoid the approaching airguns 

(or vessel) before being exposed to 

levels high enough for TTS to occur; 

and (3) the mitigation measures that are 

planned. 

In pinnipeds, TTS thresholds 

associated with exposure to brief pulses 

(single or multiple) of underwater sound 

have not been measured. Initial 

evidence from more prolonged (nonpulse) exposures suggested that some 

pinnipeds (harbor seals in particular) 

incur TTS at somewhat lower received 

levels than do small odontocetes 

exposed for similar durations (Kastak et 

al., 1999, 2005; Ketten et al., 2001). The 

TTS threshold for pulsed sounds has 

been indirectly estimated as being an 

SEL of approximately 171 dB re 1 

μPa2•s (Southall et al., 2007), which 

would be equivalent to a single pulse 

with received level of approximately 

181 - 186 dB re 1 μPa (rms), or a series 

of pulses for which the highest rms 

values are a few dB lower. 

Corresponding values for California sea 

lions and northern elephant seals 

(Mirounga angustirostris) are likely to be 

higher (Kastak et al., 2005). 

NMFS (1995, 2000) concluded that 

cetaceans and pinnipeds should not be 

exposed to pulsed underwater noise at 

received levels exceeding 180 and 190 

dB re 1 μPa rms, respectively. Those 

sound levels are not considered to be 

the levels above which TTS might 

occur. Rather, they were the received 

levels above which, in the view of a 

panel of bioacoustics specialists 

convened by NMFS before TTS 

measurements for marine mammals 

started to become available, one could 

not be certain that there would be no 

injurious effects, auditory or otherwise, 

to marine mammals. As summarized 

above and in Southall et al. (2007), data 

that are now available imply that TTS 

is unlikely to occur in most odontocetes 

(and probably mysticetes as well) unless 

they are exposed to a sequence of 

several airgun pulses in which the 

strongest pulse has a received level 

substantially exceeding 180 dB re 1 μPa 

rms. On the other hand, for the harbor 

seal and any species with similarly low 

TTS thresholds (possibly including the 

harbor porpoise), TTS may occur upon 

exposure to one or more airgun pulses 

whose received level equals the NMFS 

‘‘do not exceed’’ value of 190 dB re 1 

μPa rms. That criterion corresponds to 

a single-pulse SEL of 

175 - 180 dB re 1 μPa2•s in typical 

conditions, whereas TTS is suspected to 

be possible (in harbor seals) with a 

cumulative SEL of approximately 171 

dB re 1 μPa2•s. 

Permanent Threshold Shift (PTS) 

When PTS occurs, there is physical 

damage to the sound receptors in the 

ear. In severe cases, there can be total or 

partial deafness, while in other cases; 

the animal has an impaired ability to 

hear sounds in specific frequency ranges 

(Kryter, 1985). 

There is no specific evidence that 

exposure to pulses of airgun sound can 

cause PTS in any marine mammal, even 

with large arrays of airguns. However, 

given the possibility that mammals 

close to an airgun array might incur at 

least mild TTS, there has been further 

speculation about the possibility that 

some individuals occurring very close to 

airguns might incur PTS (Richardson et 

al., 1995, p. 372ff). Single or occasional 

occurrences of mild TTS are not 

indicative of permanent auditory 

damage. 

Relationships between TTS and PTS 

thresholds have not been studied in 

marine mammals, but are assumed to be 

similar to those in humans and other 

terrestrial mammals. PTS might occur at 

a received sound level at least several 

decibels above that inducing mild TTS 

if the animal were exposed to strong 

sound pulses with rapid rise time see 

Appendix B (6) of L-DEO’s EA. Based on 

data from terrestrial mammals, a 

precautionary assumption is that the 

PTS threshold for impulse sounds (such 

as airgun pulses as received close to the 

source) is at least 6 dB higher than the 

TTS threshold on a peak-pressure basis, 

and probably greater than 6 dB (Southall 

et al., 2007). On an SEL basis, Southall 

et al. (2007:441–4) estimated that 

received levels would need to exceed 

the TTS threshold by at least 15 dB for 


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there to be risk of PTS. Thus, for 

cetaceans they estimate that the PTS 

threshold might be a mammal-weighted 

(M-weighted) SEL (for the sequence of 

received pulses) of approximately 198 

dB re 1 μPa2•s (15 dB higher than the 

TTS threshold for an impulse), where 

the SEL value is accumulated over the 

sequence of pulses. Additional 

assumptions had to be made to derive 

a corresponding estimate for pinnipeds, 

as the only available data on TTSthresholds in pinnipeds pertain to nonimpulse sound. Southall et al. (2007) 

estimate that the PTS threshold could be 

a cumulative Mpw-weighted SEL of 

approximately 186 dB re 1 μPa2•s in the 

harbor seal exposed to impulse sound. 

The PTS threshold for the California sea 

lion and northern elephant seal the PTS 

threshold would probably be higher, 

given the higher TTS thresholds in 

those species. 

Southall et al. (2007) also note that, 

regardless of the SEL, there is concern 

about the possibility of PTS if a cetacean 

or pinniped received one or more pulses 

with peak pressure exceeding 230 or 

218 dB re 1 μPa (peak), respectively. A 

peak pressure of 230 dB re 1 FPa (3.2 

bar•m, 0–peak) would only be found 

within a few meters of the largest (360 

in3) airgun in the planned airgun array 

(Caldwell and Dragoset, 2000). A peak 

pressure of 218 dB re 1 μPa could be 

received somewhat farther away; to 

estimate that specific distance, one 

would need to apply a model that 

accurately calculates peak pressures in 

the nearfield around an array of airguns. 

Given the higher level of sound 

necessary to cause PTS as compared 

with TTS, it is considerably less likely 

that PTS would occur. Baleen whales 

generally avoid the immediate area 

around operating seismic vessels, as do 

some other marine mammals and sea 

turtles. The planned monitoring and 

mitigation measures, including visual 

monitoring, PAM, power downs, and 

shut downs of the airguns when 

mammals are seen within or 

approaching the exclusion zones, will 

further reduce the probability of 

exposure of marine mammals to sounds 

strong enough to induce PTS. 

Non-auditory Physiological Effects 

Non-auditory physiological effects or 

injuries that theoretically might occur in 

marine mammals exposed to strong 

underwater sound include stress, 

neurological effects, bubble formation, 

resonance, and other types of organ or 

tissue damage (Cox et al., 2006; Southall 

et al., 2007). Studies examining such 

effects are limited. However, resonance 

(Gentry, 2002) and direct noise-induced 

bubble formation (Crum et al., 2005) are 

not expected in the case of an impulsive 

source like an airgun array. If seismic 

surveys disrupt diving patterns of deepdiving species, this might perhaps result 

in bubble formation and a form of the 

bends, as speculated to occur in beaked 

whales exposed to sonar. However, 

there is no specific evidence of this 

upon exposure to airgun pulses. 

In general, very little is known about 

the potential for seismic survey sounds 

(or other types of strong underwater 

sounds) to cause non-auditory physical 

effects in marine mammals. Such 

effects, if they occur at all, would 

presumably be limited to short distances 

and to activities that extend over a 

prolonged period. The available data do 

not allow identification of a specific 

exposure level above which nonauditory effects can be expected 

(Southall et al., 2007), or any 

meaningful quantitative predictions of 

the numbers (if any) of marine mammals 

that might be affected in those ways. 

Marine mammals that show behavioral 

avoidance of seismic vessels, including 

most baleen whales, some odontocetes, 

and some pinnipeds, are especially 

unlikely to incur non-auditory physical 

effects. Also, the planned mitigation 

measures (see section XI), including 

shut downs of the airguns, will reduce 

any such effects that might otherwise 

occur. 

Strandings and Mortality 

Marine mammals close to underwater 

detonations of high explosives can be 

killed or severely injured, and the 

auditory organs are especially 

susceptible to injury (Ketten et al., 1993; 

Ketten, 1995). However, explosives are 

no longer used for marine seismic 

research or commercial seismic surveys, 

and have been replaced entirely by 

airguns or related non-explosive pulse 

generators. Airgun pulses are less 

energetic and have slower rise times, 

and there is no specific evidence that 

they can cause serious injury, death, or 

stranding even in the case of large 

airgun arrays. However, the association 

of mass strandings of beaked whales 

with naval exercises and, in one case, an 

L-DEO seismic survey (Malakoff, 2002; 

Cox et al., 2006), has raised the 

possibility that beaked whales exposed 

to strong pulsed sounds may be 

especially susceptible to injury and/or 

behavioral reactions that can lead to 

stranding (e.g., Hildebrand, 2005; 

Southall et al., 2007). Appendix B (7) of 

L-DEO’s EA provides additional details. 

Specific sound-related processes that 

lead to strandings and mortality are not 

well documented, but may include: (1) 

swimming in avoidance of a sound into 

shallow water; (2) a change in behavior 

(such as a change in diving behavior) 

that might contribute to tissue damage, 

gas bubble formation, hypoxia, cardiac 

arrhythmia, hypertensive hemorrhage or 

other forms of trauma; (3) a 

physiological change such as a 

vestibular response leading to a 

behavioral change or stress-induced 

hemorrhagic diathesis, leading in turn 

to tissue damage; and (4) tissue damage 

directly from sound exposure, such as 

through acoustically mediated bubble 

formation and growth or acoustic 

resonance of tissues. There are 

increasing indications that gas-bubble 

disease (analogous to ‘‘the bends’’), 

induced in supersaturated tissue by a 

behavioral response to acoustic 

exposure, could be a pathologic 

mechanism for the strandings and 

mortality of some deep-diving cetaceans 

exposed to sonar. However, the 

evidence for this remains circumstantial 

and associated with exposure to naval 

mid-frequency sonar, not seismic 

surveys (Cox et al., 2006; Southall et al., 

2007). 

Seismic pulses and mid-frequency 

sonar signals are quite different, and 

some mechanisms by which sonar 

sounds have been hypothesized to affect 

beaked whales are unlikely to apply to 

airgun pulses. Sounds produced by 

airgun arrays are broadband impulses 

with most of the energy below 1 kHz. 

Typical military mid-frequency sonars 

emit non-impulse sounds at frequencies 

of 2–10 kHz, generally with a relatively 

narrow bandwidth at any one time. A 

further difference between seismic 

surveys and naval exercises is that naval 

exercises can involve sound sources on 

more than one vessel. Thus, it is not 

appropriate to assume that there is a 

direct connection between the effects of 

military sonar and seismic surveys on 

marine mammals. However, evidence 

that sonar signals can, in special 

circumstances, lead (at least indirectly) 

to physical damage and mortality (e.g., 

Balcomb and Claridge, 2001; NOAA and 

USN, 2001; Jepson et al., 2003; 

Fernandez et al., 2004, 2005; 

Hildebrand, 2005; Cox et al., 2006) 

suggests that caution is warranted when 

dealing with exposure of marine 

mammals to any high-intensity pulsed 

sound. 

There is no conclusive evidence of 

cetacean strandings or deaths at sea as 

a result of exposure to seismic surveys, 

but a few cases of strandings in the 

general area where a seismic survey was 

ongoing have led to speculation 

concerning a possible link between 

seismic surveys and strandings. 

Suggestions that there was a link 

between seismic surveys and strandings 

of humpback whales in Brazil (Engel et 


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al., 2004) were not well founded (IAGC, 

2004; IWC, 2007). In September 2002, 

there was a stranding of two Cuvier’s 

beaked whales (Ziphius cavirostris) in 

the Gulf of California, Mexico, when the 

L-DEO vessel R/V Maurice Ewing was 

operating a 20–airgun, 8490–in3 airgun 

array in the general area. The link 

between the stranding and the seismic 

surveys was inconclusive and not based 

on any physical evidence (Hogarth, 

2002; Yoder, 2002). Nonetheless, the 

Gulf of California incident plus the 

beaked whale strandings near naval 

exercises involving use of midfrequency sonar suggests a need for 

caution in conducting seismic surveys 

in areas occupied by beaked whales 

until more is known about effects of 

seismic surveys on those species 

(Hildebrand, 2005). 

No injuries of beaked whales are 

anticipated during the proposed study 

because of: (1) the high likelihood that 

any beaked whales nearby would avoid 

the approaching vessel before being 

exposed to high sound levels; (2) the 

proposed monitoring and mitigation 

measures; and (3) differences between 

the sound sources operated by L-DEO 

and those involved in the naval 

exercises associated with strandings. 

Possible Effects of Multibeam 

Echosounder (MBES) Signals 

The Simrad EM120 12–kHz MBES 

will be operated from the source vessel 

continuously during the planned study. 

Sounds from the MBES are very short 

pulses, occurring for 2–15 ms once 

every 5 20 s, depending on water depth. 

Most of the energy in the sound pulses 

emitted by this MBES is at frequencies 

near 12 kHz, and the maximum source 

level is 242 dB re 1 μPa• m (rms). The 

beam is narrow (1°) in fore-aft extent 

and wide (150°) in the cross-track 

extent. Each ping consists of nine 

successive fan-shaped transmissions 

(segments) at different cross-track 

angles. Any given mammal at depth 

near the trackline would be in the main 

beam for only one or two of the nine 

segments. Also, marine mammals that 

encounter the Simrad EM120 are 

unlikely to be subjected to repeated 

pulses because of the narrow fore aft 

width of the beam and will receive only 

limited amounts of pulse energy 

because of the short pulses. Animals 

close to the ship (where the beam is 

narrowest) are especially unlikely to be 

ensonified for more than one 2 15 ms 

pulse (or two pulses if in the overlap 

area). Similarly, Kremser et al. (2005) 

noted that the probability of a cetacean 

swimming through the area of exposure 

when an MBES emits a pulse is small. 

The animal would have to pass the 

transducer at close range and be 

swimming at speeds similar to the 

vessel in order to receive the multiple 

pulses that might result in sufficient 

exposure to cause TTS. 

Navy sonars that have been linked to 

avoidance reactions and stranding of 

cetaceans: (1) generally have longer 

pulse duration than the Simrad EM120, 

and (2) are often directed close to 

omnidirectionally versus more 

downward for the Simrad EM120. The 

area of possible influence of the MBES 

is much smaller a narrow band below 

the source vessel. The duration of 

exposure for a given marine mammal 

can be much longer for naval sonar. 

During L-DEO’s operations, the 

individual pulses will be very short, and 

a given mammal would not receive 

many of the downward-directed pulses 

as the vessel passes by the area. 

Masking - Marine mammal 

communications will not be masked 

appreciably by the MBES signals given 

the low duty cycle of the echosounder 

and the brief period when an individual 

mammal is likely to be within its beam. 

Furthermore, in the case of baleen 

whales, the MBES signals (12 kHz) do 

not overlap with the predominant 

frequencies in the calls, which would 

avoid any significant masking. 

Behavioral Responses: Behavioral 

reactions of free-ranging marine 

mammals to sonar, echosounders, and 

other sound sources appear to vary by 

species and circumstance. Observed 

reactions have included silencing and 

dispersal by sperm whales (Watkins et 

al., 1985), increased vocalizations and 

no dispersal by pilot whales 

(Globicephala spp.) (Rendell and 

Gordon, 1999), and the previouslymentioned beachings by beaked whales. 

During exposure to a 21–25 kHz sonar 

with a source level of 215 dB re 1 

μPa•m, gray whales reacted by orienting 

slightly away from the source and being 

deflected from their course by 

approximately 200 m (Frankel, 2005). 

When a 38–kHz echosounder and a 

150–kHz acoustic Doppler current 

profiler were transmitting during 

studies in the Eastern Tropical Pacific, 

baleen whales showed no significant 

responses, while spotted and spinner 

dolphins were detected slightly more 

often and beaked whales less often 

during visual surveys (Gerrodette and 

Pettis, 2005). 

Captive bottlenose dolphins exhibited 

changes in behavior when exposed to 1– 

s tonal signals at frequencies similar to 

those that will be emitted by the MBES 

used by L-DEO, and to shorter 

broadband pulsed signals. Behavioral 

changes typically involved what 

appeared to be deliberate attempts to 

avoid the sound exposure (Schlundt et 

al., 2000; Finneran et al., 2002; Finneran 

and Schlundt, 2004). The relevance of 

those data to free-ranging odontocetes is 

uncertain, and in any case, the test 

sounds were quite different in duration 

as compared with those from an MBES. 

Very few data are available on the 

reactions of pinnipeds to sonar sounds 

at frequencies similar to those used 

during seismic operations. Hastie and 

Janik (2007) conducted a series of 

behavioral response tests on two captive 

gray seals to determine their reactions to 

underwater operation of a 375–kHz 

multibeam imaging sonar that included 

significant signal components down to 6 

kHz. Results indicated that the two seals 

reacted to the sonar signal by 

significantly increasing their dive 

durations. Because of the likely brevity 

of exposure to the MBES sounds, 

pinniped reactions are expected to be 

limited to startle or otherwise brief 

responses of no lasting consequence to 

the animals. 

Hearing Impairment and Other 

Physical Effects: Given recent stranding 

events that have been associated with 

the operation of naval sonar, there is 

concern that mid-frequency sonar 

sounds can cause serious impacts to 

marine mammals (see above). However, 

the MBES proposed for use by L-DEO is 

quite different than sonars used for navy 

operations. Pulse duration of the MBES 

is very short relative to the naval sonars. 

Also, at any given location, an 

individual marine mammal would be in 

the beam of the MBES for much less 

time given the generally downward 

orientation of the beam and its narrow 

fore-aft beamwidth; navy sonars often 

use nearhorizontally-directed sound. 

Those factors would all reduce the 

sound energy received from the MBES 

rather drastically relative to that from 

the sonars used by the navy. 

Given the maximum source level of 

242 dB re 1 μPa•m rms, the received 

level for an animal within the MBES 

beam 100 m (328 ft) below the ship 

would be approximately 202 dB re 1 μPa 

rms, assuming 40 dB of spreading loss 

over 100 m (328 ft) (circular spreading). 

Given the narrow beam, only one pulse 

is likely to be received by a given 

animal as the ship passes overhead. The 

received energy level from a single 

pulse ofduration 15 ms would be about 

184 dB re 1 μPa2•s, i.e., 202 dB + 10 log 

(0.015 s). That is below the TTS 

threshold for a cetacean receiving a 

single non-impulse sound (195 dB re 1 

μPa2•s) and even further below the 

anticipated PTS threshold (215 dB re 1 

μPa2•s) (Southall et al., 2007). In 

contrast, an animal that was only 10 m 

(32 ft) below the MBES when a ping is 


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21642 Federal Register / Vol. 74, No. 88 / Friday, May 8, 2009 / Notices 

emitted would be expected to receive a 

level approximately 20 dB higher, i.e., 

204 dB re 1 μPa2•s in the case of the 

EM120. That animal might incur some 

TTS (which would be fully recoverable), 

but the exposure would still be below 

the anticipated PTS threshold for 

cetaceans. As noted by Burkhardt et al., 

(2007, 2008), cetaceans are very unlikely 

to incur PTS from operation of scientific 

sonars on a ship that is underway. 

In the harbor seal, the TTS threshold 

for non-impulse sounds is about 183 dB 

re 1 μPa2•s, as compared with 

approximately 195 dB re 1 μPa2•s in 

odontocetes (Kastak et al., 2005; 

Southall et al., 2007). TTS onset occurs 

at higher received energy levels in the 

California sea lion and northern 

elephant seal than in the harbor seal. A 

harbor seal as much as 100 m (328 ft) 

below the Langseth could receive a 

single MBES pulse with received energy 

level of greater than or equal to 184 dB 

re 1 μPa2•s (as calculated in the toothed 

whale subsection above) and thus could 

incur slight TTS. Species of pinnipeds 

with higher TTS thresholds would not 

incur TTS unless they were closer to the 

transducers when a sonar ping was 

emitted. However, the SEL criterion for 

PTS in pinnipeds (203 dB re 1 μPa2•s) 

might be exceeded for a ping received 

within a few meters of the transducers, 

although the risk of PTS is higher for 

certain species (e.g., harbor seal). Given 

the intermittent nature of the signals 

and the narrow MBES beam, only a 

small fraction of the pinnipeds below 

(and close to) the ship would receive a 

pulse as the ship passed overhead. 

Possible Effects of the Sub-bottom 

Profiler Signals 

An SBP may be operated from the 

source vessel at times during the 

planned study. Sounds from the subbottom profiler are very short pulses, 

occurring for 1 4 ms once every second. 

Most of the energy in the sound pulses 

emitted by the SBP is at 3.5 kHz, and 

the beam is directed downward in a 

narrow beam with a spacing of up to 15° 

and a fan width up to 30°. The subbottom profiler on the Langseth has a 

maximum source level of 204 dB re 1 

μPa•m. Kremser et al. (2005) noted that 

the probability of a cetacean swimming 

through the area of exposure when a 

bottom profiler emits a pulse is smalleven for an SBP more powerful than 

that on the Langseth if the animal was 

in the area, it would have to pass the 

transducer at close range and in order to 

be subjected to sound levels that could 

cause TTS. 

Masking - Marine mammal 

communications will not be masked 

appreciably by the sub-bottom profiler 

signals given their directionality and the 

brief period when an individual 

mammal is likely to be within its beam. 

Furthermore, in the case of most baleen 

whales, the SBP signals do not overlap 

with the predominant frequencies in the 

calls, which would avoid significant 

masking. 

Behavioral Responses - Marine 

mammal behavioral reactions to other 

pulsed sound sources are discussed 

above, and responses to the SBP are 

likely to be similar to those for other 

pulsed sources if received at the same 

levels. However, the pulsed signals from 

the SBP are considerably weaker than 

those from the MBES. Therefore, 

behavioral responses would not be 

expected unless marine mammals were 

to approach very close to the source. 

Hearing Impairment and Other 

Physical Effects: It is unlikely that the 

SBP produces pulse levels strong 

enough to cause hearing impairment or 

other physical injuries even in an 

animal that is (briefly) in a position near 

the source. The SBP is usually operated 

simultaneously with other higher-power 

acoustic sources. Many marine 

mammals will move away in response 

to the approaching higher-power 

sources or the vessel itself before the 

mammals would be close enough for 

there to be any possibility of effects 

from the less intense sounds from the 

SBP. In the case of mammals that do not 

avoid the approaching vessel and its 

various sound sources, mitigation 

measures that would be applied to 

minimize effects of other sources would 

further reduce or eliminate any minor 

effects of the SBP. 

Possible Effects of the Acoustic Release 

Signals 

The acoustic release transponder used 

to communicate with the OBS uses 

frequencies of 9 13 kHz. Once the OBS 

is ready to be retrieved, an acoustic 

release transponder interrogates the 

OBS at a frequency of 9 11 kHz, and a 

response is received at a frequency of 9 

13 kHz. However, these signals will be 

used very intermittently. The source 

level of the release signal is 190 dB (re 

1 μPa at 1 m). An animal would have 

to pass by the OBS at close range when 

the signal is emitted in order to be 

exposed to any pulses at that level. The 

sound is expected to undergo a 

spreading loss of approximately 40 dB 

in the first 100 m (328 ft). Thus, any 

animals located 100 m (328 ft) or more 

from the signal will be exposed to very 

weak signals (less than 150 dB) that are 

not expected to have any effects. The 

signal is used only for short intervals to 

interrogate and trigger the release of the 

OBS and consists of pulses rather than 

a continuous sound. Given the short 

duration use of this signal and rapid 

attenuation in seawater it is unlikely 

that the acoustic release signals would 

significantly affect marine mammals or 

sea turtles through masking, 

disturbance, or hearing impairment. 

Any effects likely would be negligible 

given the brief exposure at presumable 

low levels. 

Proposed Monitoring and Mitigation 

Measures 

Monitoring 

L-DEO proposes to sponsor marine 

mammal monitoring during the present 

project, in order to implement the 

proposed mitigation measures that 

require real-time monitoring, and to 

satisfy the anticipated monitoring 

requirements of the IHA. L-DEO’s 

proposed Monitoring Plan is described 

below this section. L-DEO understands 

that this monitoring plan will be subject 

to review by NMFS, and that 

refinements may be required. The 

monitoring work described here has 

been planned as a self-contained project 

independent of any other related 

monitoring projects that may be 

occurring simultaneously in the same 

regions. L-DEO is prepared to discuss 

coordination of its monitoring program 

with any related work that might be 

done by other groups insofar as this is 

practical and desirable. 

Vessel-based Visual Monitoring 

Marine mammal visual observers 

(MMVOs) will be based aboard the 

seismic source vessel and will watch for 

marine mammals and turtles near the 

vessel during daytime airgun operations 

and during any start-ups at night. The 

MMVOs will also watch for marine 

mammals and turtles near the seismic 

vessel for at least 30 minutes (min) prior 

to the start of airgun operations after an 

extended shut down. When feasible, 

MMVOs will also observe during 

daytime periods when the seismic 

system is not operating for comparison 

of sighting rates and behavior with 

versus without airgun operations. Based 

on the MMVOs’ observations, the 

Langseth will power down the airguns 

or shut down the airguns when marine 

mammals are observed within or about 

to enter a designated exclusion zone 

(EZ). The EZ is a region in which a 

possibility exists of adverse effects on 

animal hearing or other physical effects. 

During seismic operations in the 

Endeavour MPA, at least three MMVOs 

will be based aboard the Langseth. 

MMVOs will be appointed by L-DEO 

with NMFS concurrence. At least one 

MMVO, and when feasible, two 


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MMVOs, will monitor marine mammals 

and turtles near the seismic vessel 

during ongoing daytime operations and 

nighttime start ups of the airguns. Use 

of two simultaneous observers will 

increase the proportion of the animals 

present near the source vessel that are 

detected. MMVO(s) will be on duty in 

shifts of duration no longer than 4 h. 

Other crew will also be instructed to 

assist in detecting marine mammals and 

turtles and implementing mitigation 

requirements (if feasible). Before the 

start of the seismic survey the crew will 

be given additional instruction 

regarding how to do so. 

The Langseth is a suitable platform for 

marine mammal and turtle observations. 

When stationed on the observation 

platform, the eye level will be 

approximately 18 m (59 ft) above sea 

level, and the observer will have a good 

view around the entire vessel. During 

daytime, the MMVOs will scan the area 

around the vessel systematically with 

reticle binoculars (e.g., 7 50 Fujinon), 

Big-eye binoculars (25 150), and with 

the naked eye. During darkness, night 

vision devices (NVDs) will be available 

(ITT F500 Series Generation 3 

binocularimage intensifier or 

equivalent), when required. Laser 

rangefinding binoculars (Leica LRF 1200 

laser rangefinder or equivalent) will be 

available to assist with distance 

estimation. Those are useful in training 

observers to estimate distances visually, 

but are generally not useful in 

measuring distances to animals directly; 

that is done primarily with the reticles 

in the binoculars. 

The vessel-based monitoring will 

provide data to estimate the numbers of 

marine mammals exposed to various 

received sound levels, to document any 

apparent disturbance reactions or lack 

thereof, and thus to estimate the 

numbers of mammals potentially 

‘‘taken’’ by harassment. It will also 

provide the information needed in order 

to power down or shut down the 

airguns at times when mammals and 

turtles are present in or near the safety 

radii. When a sighting is made, the 

following information about the sighting 

will be recorded: 

1. Species, group size, age/size/sex 

categories (if determinable), behavior 

when first sighted and after initial 

sighting, heading (if consistent), bearing 

and distance from seismic vessel, 

sighting cue, apparent reaction to the 

airguns or vessel (e.g., none, avoidance, 

approach, paralleling, etc.), and 

behavioral pace. 

2. Time, location, heading, speed, 

activity of the vessel, sea state, 

visibility, and sun glare. 

The data listed under (2) will also be 

recorded at the start and end of each 

observation watch, and during a watch 

whenever there is a change in one or 

more of the variables. 

All observations and power-downs or 

shut downs will be recorded in a 

standardized format. Data will be 

entered into a custom database using a 

notebook computer. The accuracy of the 

data entry will be verified by 

computerized validity data checks as 

the data are entered and by subsequent 

manual checking of the database. 

Preliminary reports will be prepared 

during the field program and summaries 

forwarded to the operating institution’s 

shore facility and to NSF weekly or 

more frequently. 

Results from the vessel-based 

observations will provide: 

1. The basis for real-time mitigation 

(airgun power-down or shut-down). 

2. Information needed to estimate the 

number of marine mammals potentially 

taken by harassment, which must be 

reported to NMFS per terms of MMPA 

authorizations or regulations. 

3. Data on the occurrence, 

distribution, and activities of marine 

mammals and turtles in the area where 

the seismic study is conducted. 

4. Data on the behavior and 

movement patterns of marine mammals 

and turtles seen at times with and 

without seismic activity. 

Passive Acoustic Monitoring 

Passive acoustic monitoring (PAM) 

will take place to complement the visual 

monitoring program. Visual monitoring 

typically is not effective during periods 

of bad weather or at night, and even 

with good visibility, is unable to detect 

marine mammals when they are below 

the surface or beyond visual range. 

Acoustical monitoring can be used in 

addition to visual observations to 

improve detection, identification, 

localization, and tracking of cetaceans. 

The acoustic monitoring will serve to 

alert visual observers (if on duty) when 

vocalizing cetaceans are detected. It is 

only useful when marine mammals call, 

but it can be effective either by day or 

by night, and does not depend on good 

visibility. It will be monitored in real 

time so that the visual observers can be 

advised when cetaceans are detected. 

When bearings (primary and mirrorimage) to calling cetacean(s) are 

determined, the bearings will be relayed 

to the visual observer to help him/her 

sight the calling animal(s). 

The PAM system consists of hardware 

(i.e., hydrophones) and software. The 

‘‘wet end’’ of the system consists of a 

low-noise, towed hydrophone array that 

is connected to the vessel by a ‘‘hairy’’ 

faired cable. The array will be deployed 

from a winch located on the back deck. 

A deck cable will connect from the 

winch to the main computer lab where 

the acoustic station and signal 

conditioning and processing system will 

be located. The lead-in from the 

hydrophone array is approximately 400 

m (1312 ft) long, and the active part of 

the hydrophone array is approximately 

50 m (164 ft) long. The hydrophone 

array is typically towed at depths of 20 

m (66 ft) to 30 m (98 ft). 

The towed hydrophones will be 

monitored 24 h per day while at the 

seismic survey area during airgun 

operations, and during most periods 

when the Langseth is underway while 

the airguns are not operating. One MMO 

will monitor the acoustic detection 

system at any one time, by listening to 

the signals from two channels via 

headphones and/or speakers and 

watching the real-time spectrographic 

display for frequency ranges produced 

by cetaceans. MMOs monitoring the 

acoustical data will be on shift for 1 6 

h at a time. Besides the visual MMOs, 

an additional MMO with primary 

responsibility for PAM will also be 

aboard. All MMOs are expected to rotate 

through the PAM position, although the 

most experienced with acoustics will be 

on PAM duty more frequently. 

When a vocalization is detected while 

visual observations are in progress, the 

acoustic MMO will contact the visual 

MMO immediately, to alert him/her to 

the presence of cetaceans (if they have 

not already been seen), and to allow a 

power down or shut down to be 

initiated, if required. The information 

regarding the call will be entered into a 

database. The data to be entered include 

an acoustic encounter identification 

number, whether it was linked with a 

visual sighting, date, time when first 

and last heard and whenever any 

additional information was recorded, 

position and water depth when first 

detected, bearing if determinable, 

species or species group (e.g., 

unidentified dolphin, sperm whale), 

types and nature of sounds heard (e.g., 

clicks, continuous, sporadic, whistles, 

creaks, burst pulses, strength of signal, 

etc.), and any other notable information. 

The acoustic detection can also be 

recorded for further analysis. 

Mitigation 

L-DEO’s mitigation procedures are 

based on protocols used during previous 

L-DEO seismic research cruises as 

approved by NMFS, and on best 

practices recommended in Richardson 

et al. (1995), Pierson et al. (1998), and 

Weir and Dolman (2007). The measures 


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are described in detail below this 

section. 

Proposed Exclusion Zones 

As noted earlier, L-DEO modeled 

received sound levels for the 36–airgun 

array and for a single 1900LL 40–in3

airgun (which will be used during 

power downs), in relation to distance 

and direction from the airguns. Based 

on the modeling for deep water, the 

distances from the source where sound 

levels are predicted to be 190, 180, and 

160 dB re 1 μPa (rms) were determined 

(Table 1). The 180- and 190–dB radii 

vary with tow depth of the airgun array 

and range up to 1220 m (4002 ft) and 

380 m (1246 ft), respectively. The 180- 

and 190–dB levels are shut-down 

criteria applicable to cetaceans and 

pinnipeds, respectively, as specified by 

NMFS (2000); these levels were used to 

establish the exclusion zones (EZ). If the 

MMO detects marine mammal(s) or 

turtle(s) within or about to enter the 

appropriate safety radii, the airguns will 

be powered down (or shut down if 

necessary) immediately. 

Mitigation During Operations 

Mitigation measures that will be 

adopted during the L-DEO survey 

include: (1) speed or course alteration, 

provided that doing so will not 

compromise operational safety 

requirements; (2) power-down 

procedures; (3) shut-down procedures; 

(4) ramp-up procedures; and (5) special 

procedures for species of particular 

concern. 

Speed or Course Alteration - If a 

marine mammal or sea turtle is detected 

outside the safety zone and, based on its 

position and the relative motion, is 

likely to enter the safety zone, the 

vessel’s speed and/or direct course may 

be changed. This would be done if 

practicable while minimizing the effect 

on the planned science objectives. The 

activities and movements of the marine 

mammal or sea turtle (relative to the 

seismic vessel) will then be closely 

monitored to determine whether the 

animal is approaching the applicable 

safety zone. If the animal appears likely 

to enter the safety zone, further 

mitigative actions will be taken, i.e., 

either further course alterations or a 

power down or shut down of the 

airguns. Typically, during seismic 

operations that use hydrophone 

streamers, the source vessel is unable to 

change speed or course and one or more 

alternative mitigation measures (see 

below) will need to be implemented. 

Power-down Procedures - A powerdown involves decreasing the number of 

airguns in use such that the radius of 

the 180–dB (or 190–dB) zone is 

decreased to the extent that marine 

mammals or turtles are no longer in or 

about to enter the safety zone. A powerdown of the airgun array can also occur 

when the vessel is moving from one 

seismic line to another. During a powerdown for mitigation, one airgun will be 

operated. The continued operation of 

one airgun is intended to alert marine 

mammals and turtles to the presence of 

the seismic vessel in the area. In 

contrast, a shut-down occurs when all 

airgun activity is suspended. 

If a marine mammal or turtle is 

detected outside the EZ but is likely to 

enter the EZ, and if the vessel’s speed 

and/or course cannot be changed to 

avoid having the animal enter the safety 

radius, the airguns will be powered 

down before the animal is within the 

EZ. Likewise, if a mammal or turtle is 

already within the EZ when first 

detected, the airguns will be powered 

down immediately. During a powerdown of the airgun array, the 40–in3

airgun will be operated. If a marine 

mammal or turtle is detected within or 

near the smaller EZ around that single 

airgun (Table 1), it will be shut down 

(see next subsection). 

Following a power-down, airgun 

activity will not resume until the marine 

mammal or turtle has cleared the EZ. 

The animal will be considered to have 

cleared the EZ if it: (1) is visually 

observed to have left the EZ; or (2) has 

not been seen within the zone for 15 

min in the case of small odontocetes; or 

(3) has not been seen within the zone for 

30 min in the case of mysticetes and 

large odontocetes, including sperm, 

pygmy sperm, dwarf sperm, and beaked 

whales; or (4) the vessel has moved 

outside the EZ for turtles, i.e., 

approximately 5 to 20 min, depending 

on the sighting distance, vessel speed, 

and tow-depth. 

During airgun operations following a 

power down (or shut down) whose 

duration has exceeded the limits 

specified above, the airgun array will be 

ramped up gradually (see below). 

Shut-down Procedures - During a 

power down, the operating airgun will 

be shut down if a marine mammal or 

turtle is seen within or approaching the 

EZ for a single airgun. Shut-downs will 

be implemented: (1) if an animal enters 

the exclusion zone of the single airgun 

after a power-down has been initiated, 

or (2) if an animal is initially seen 

within the exclusion zone of a single 

airgun when more than one airgun 

(typically the full array) is operating. 

Airgun activity will not resume until 

the marine mammal or turtle has cleared 

the EZ, or until the visual marine 

mammal observer (MMVO) is confident 

that the animal has left the vicinity of 

the vessel. Criteria for judging that the 

animal has cleared the EZ will be as 

described in the preceding subsection. 

The airguns will be shut down if a 

North Pacific right whale is sighted from 

the vessel, even if it is located outside 

the EZ, because of the rarity and 

sensitive status of this species. 

Ramp-up Procedures - A ramp-up 

procedure will be followed when the 

airgun array begins operating after a 

specified period without airgun 

operations or when a power-down has 

exceeded that period. It is proposed 

that, for the present cruise, this period 

would be approximately 9 min. This 

period is based on the largest modeled 

180–dB radius for the 36–airgun array 

(see Table 1) in relation to the planned 

speed of the Langseth while shooting 

the airguns. Similar periods 

(approximately 8 10 min) were used 

during previous L-DEO surveys. 

Ramp-up will begin with the smallest 

gun in the array (40 in3). Airguns will 

be added in a sequence such that the 

source level of the array will increase in 

steps not exceeding 6 dB per 5–min 

period over a total duration of about 30 

- 40 min. During ramp-up, the MMVOs 

will monitor the safety zone and if 

marine mammals or turtles are sighted, 

a course/speed change, power down, or 

shut down will be implemented as 

though the full array were operational. 

If the complete EZ has not been 

visible for at least 30 min prior to the 

start of operations in either daylight or 

nighttime, ramp-up will not commence 

unless at least one airgun (40 in3 or 

similar) has been operating during the 

interruption of seismic survey 

operations. Given these provisions, it is 

likely that the airgun array will not be 

ramped up from a complete shut-down 

at night or in thick fog, because the 

outer part of the EZ for that array will 

not be visible during those conditions. 

If one airgun has operated during a 

power-down period, ramp-up to full 

power will be permissible at night or in 

poor visibility, on the assumption that 

marine mammals and turtles will be 

alerted to the approaching seismic 

vessel by the sounds from the single 

airgun and could move away if they 

choose. Ramp-up of the airguns will not 

be initiated if a sea turtle or marine 

mammal is sighted within or near the 

applicable zones during the day or close 

to the vessel at night. 

Shutdown if Injured or Dead Whale is 

Found - In the unanticipated event that 

any cases of marine mammal injury or 

mortality are found and are judged 

likely to have resulted from these 

activities, L-DEO will cease operating 

seismic airguns and report the incident 


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to the Office of Protected Resources, 

NMFS immediately. 

Reporting 

L-DEO will submit a report to NMFS 

within 90 days after the end of the 

cruise. The report will describe the 

operations that were conducted and 

sightings of marine mammals and 

turtles near the operations. The report 

will provide full documentation of 

methods, results, and interpretation 

pertaining to all monitoring. The 90–day 

report will summarize the dates and 

locations of seismic operations, and all 

marine mammal and turtle sightings 

(dates, times, locations, activities, 

associated seismic survey activities). 

The report will also include estimates of 

the number and nature of exposures that 

could result in ‘‘takes’’ of marine 

mammals by harassment or in other 

ways. 

All injured or dead marine mammals 

(regardless of cause) must be reported to 

NMFS as soon as practicable. Report 

should include species or description of 

animal, condition of animal, location, 

time first found, observed behaviors (if 

alive) and photo or video, if available. 

Estimated Take by Incidental 

Harassment 

Because of the mitigation measures 

that will be required and the likelihood 

that some cetaceans will avoid the area 

around the operating airguns of their 

own accord, NMFS does not expect any 

marine mammals to approach the sound 

source close enough to be injured (Level 

A harassment). All anticipated takes 

would be ‘‘takes by Level B 

harassment’’, as described previously, 

involving temporary behavioral 

modifications or low-level physiological 

effects. 

Estimates of the numbers of marine 

mammals that might be affected are 

based on consideration of the number of 

marine mammals that could be 

disturbed appreciably by approximately 

1800 km (1118 mi) of seismic surveys 

during the proposed seismic program in 

the Endeavor MPA. 

It is assumed that, during 

simultaneous operations of the airgun 

array and the other sources, any marine 

mammals close enough to be affected by 

the MBES or SBP would already be 

affected by the airguns. However, 

whether or not the airguns are operating 

simultaneously with the other sources, 

marine mammals are expected to exhibit 

no more than short-term and 

inconsequential responses to the MBES 

and SBP given their characteristics (e.g., 

narrow downward-directed beam) and 

other considerations described in 

section I of L-DEO’s application. Such 

reactions are not considered to 

constitute ‘‘taking’’ (NMFS, 2001). 

Therefore, no additional allowance is 

included for animals that might be 

affected by sound sources other than 

airguns. 

Density Estimates 

There is very little information on the 

cetaceans that occur in deep water off 

the west coast of Vancouver Island, but 

the waters off Oregon and Washington 

have been studied in some detail (e.g., 

Green et al., 1992, 1993; Barlow, 1997, 

2003; Barlow and Taylor, 2001; 

Calambokidis and Barlow, 2004; Barlow 

and Forney, 2007). The primary data 

used to provide densities for the 

proposed project area off southwestern 

British Columbia (BC) were obtained 

from the 1996, 2001, and 2005 NMFS/ 

SWFSC ‘‘ORCAWALE’’ or ‘‘CSCAPE’’ 

ship surveys off Oregon/Washington, as 

synthesized by Barlow and Forney 

(2007). The surveys took place up to 

approximately 550 km (341 mi) offshore 

from June or July through November or 

December. Thus, the surveys included 

effort in coastal, shelf/slope, and 

offshore water, and they encompass the 

August September period for the 

proposed study. Systematic, offshore 

survey data for pinnipeds are more 

limited. The most comprehensive such 

studies are reported by Bonnell et al., 

(1992) based on systematic aerial 

surveys conducted in 1989 1990. 

The waters off the west coast of 

Vancouver Island are included in the 

same ecological province as Oregon/ 

Washington, the California Coastal 

Province (Longhurst, 2007). Thus, 

information on cetaceans from Oregon/ 

Washington is relevant to the proposed 

offshore study area far offshore of BC. 

Although densities for BC are available 

for some cetacean species (see Williams 

and Thomas 2007), these are for inshore 

coastal waters and would not be 

representative of the densities occurring 

in offshore areas. Although the cetacean 

densities based on data from Barlow and 

Forney (2007) better reflect those that 

will be encountered during the ETOMO 

study, the actual densities in the 

Endeavour MPA are expected to be 

lower still, as the survey effort off 

Oregon/Washington covered offshore as 

well as shelf and coastal waters, and it 

included sightings for summer and fall. 

Oceanographic conditions, including 

occasional El Nino and La Nina events, 

influence the distribution and numbers 

of marine mammals present in the 

NEPO, resulting in considerable year-toyear variation in the distribution and 

abundance of many marine mammal 

species (Forney and Barlow, 1998; 

Buchanan et al., 2001; Escorza-Trevino, 

2002; Ferrero et al., 2002; Philbrick et 

al., 2003; Becker, 2007). Thus, for some 

species the densities derived from 

recent surveys may not be 

representative of the densities that will 

be encountered during the proposed 

seismic survey. 

Potential Number of Exposures to 

Sound Levels at or above 160 dB 

L-DEO’s ‘‘best estimate’’ of the 

potential number of exposures of 

cetaceans, absent any mitigation 

measures, to seismic sounds with 

received levels at or above 160 dB re 1 

μPa (rms) is 8,624 (Table 2). It is 

assumed that marine mammals exposed 

to airgun sounds this strong might 

change their behavior sufficiently to be 

considered ‘‘taken by harassment’’. 

The number of potential exposures to 

sound levels at or above 160 dB re 1 μPa 

(rms) were calculated by multiplying 

the expected average species density 

(see section VII of L-DEO’s application) 

times the anticipated minimum area 

(7302 km2, 4537 mi2) to be ensonified 

to that level during airgun operations 

including overlap. 

The area expected to be ensonified 

was determined by entering the planned 

survey lines into a MapInfo Geographic 

Information System (GIS), using the GIS 

to identify the relevant areas by 

‘‘drawing’’ the applicable 160–dB buffer 

around each seismic line, and then 

calculating the total area within the 

buffers. Areas where overlap occurred 

(because of closely-spaced lines) were 

included when estimating the number 

of exposures. 

Number of Individual Cetaceans 

Exposed to Sound Levels at or above 

160 dB 

L-DEO’s ‘‘best estimate’’ of the 

potential number of different 

individuals that could be exposed to 

airgun sounds with received levels at or 

above 160 dB re 1 μPa (rms) on one or 

more occasions is 1,748. That total 

includes 22 baleen whales, 17 of which 

are considered endangered under the 

ESA: six humpback whales, two blue 

whales, one sei whale, and eight fin 

whales, which would represent small 

numbers of the regional populations 

(Table 2). Ten sperm whales and 19 

beaked whales could be exposed during 

the survey as well (Table 2). 

Based on numbers of animals 

encountered during previous L-DEO 

seismic surveys, the likelihood of the 

successful implementation of the 

required mitigation measures, and the 

likelihood that some animals will avoid 

the area around the operating airguns, 

NMFS believes that L-DEO’s airgun 

seismic testing program may result in 


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the Level B harassment of some lower 

number of individual marine mammals 

(a few times each) than is indicated by 

the column titled, Number of 

Individuals Exposed to ≥160 dB 

(Request) in Table 2. L-DEO has asked 

for authorization for take of their best 

estimate of numbers for each species. 

Though NMFS believes that take of the 

requested numbers is unlikely, we still 

find these numbers small relative to the 

population sizes. 

Potential Effects on Habitat 

The proposed seismic survey will not 

result in any permanent impact on 

habitats used by marine mammals, or to 

the food sources they use. The main 

impact issue associated with the 

proposed activity will be temporarily 

elevated noise levels and the associated 

direct effects on marine mammals. 

The Langseth will deploy 16 OBS in 

the vent field grid (see Figure 1 of LDEO’s application), and will deploy 

another 48 OBS throughout the 

remaining study area in the Endeavour 

MPA. L-DEO proposes to use two 

different types of OBS: (1) the WHOI 

‘‘D2’’ OBS, which has an anchor made 

of hot-rolled steel with dimensions 2.5 

x 30.5 x 38.1 cm; and (2) the LC4x4, 

which consists of a an anchor with a 1 

m2 piece of steel grating. These OBS 

anchors will remain upon equipment 

recovery. 

Although OBS placement may disrupt 

a very small area of seafloor habitat and 

may disturb benthic invertebrates, the 

impacts are expected to be localized and 

transitory. The vessel will deploy the 

OBS in such a way that creates the least 

disturbance to the area. The vent area is 

dynamic, and the natural variability 

within the system is high; toppling and 

regrowth of sulphide structures, and 

death of assemblages are common 

(Tunnicliffe and Thomson, 1999). Thus, 

it is not expected that the placement of 

OBS would have adverse effects beyond 

naturally occurring changes in this 

environment, and any effects of the 

planned activity on marine mammal 

habitats and food resources are expected 

to be negligible. 

Potential Effects on Fish 

Existing information on the impacts of 

seismic surveys on marine fish and 

invertebrate populations is very limited 

(See Appendix D of L-DEO’s EA) and 

the vast majority of the data are in the 

form of reports and other documents 

that have not been peer reviewed 

(Popper and Hastings, 2009). 

There are three types of potential 

effects of exposure to seismic surveys: 

(1) pathological, (2) physiological, and 

(3) behavioral. 

Pathological Effects - Pathological 

effects involve lethal and temporary or 

permanent sub-lethal injury. The 

potential for pathological damage to 

hearing structures in fish depends on 

the energy level of the received sound 

and the physiology and hearing 

capability of the species in question (see 

Appendix D of L-DEO’s EA). For a given 

sound to result in hearing loss, the 

sound must exceed, by some substantial 

amount, the hearing threshold of the 

fish for that sound (Popper, 2005). The 

consequences of temporary or 

permanent hearing loss in individual 

fish on a fish population are unknown; 

however, they likely depend on the 

number of individuals affected and 

whether critical behaviors involving 

sound (e.g. predator avoidance, prey 

capture, orientation and navigation, 

reproduction, etc.) are adversely 

affected. 

Little is known about the mechanisms 

and characteristics of damage to fish 

that may be inflicted by exposure to 

seismic survey sounds. Few data have 

been presented in the peer-reviewed 

scientific literature. McCauley et al. 

(2003), found that exposure to airgun 

sound caused observable anatomical 

damage to the auditory maculae of 

‘‘pink snapper’’ (Pagrusauratus). This 

damage in the ears had not been 

repaired in fish sacrificed and examined 

almost two months after exposure. O n 

the other hand, Popper et al. (2005) 

documented only TTS (as determined 

by auditory brainstem response) in two 

of three fish species from the Mackenzie 

River Delta. This study found that broad 

whitefish (Coreogonus nasus) that 

received a sound exposure level of 177 

dB re 1 μPa2•s showed no hearing loss. 

During both studies, the repetitive 

exposure to sound was greater than 

would have occurred during a typical 

seismic survey. However, the 

substantial low-frequency energy 

produced by the airguns [less than 

approximately 400 Hz in the study by 

McCauley et al. (2003) and less than 

approximately 200 Hz in Popper et al. 

(2005)] likely did not propagate to the 

fish because the water in the study areas 

was very shallow (approximately 9 m 

(29.5 ft) in the former case and less than 

2 m (6.5 ft) in the latter). Water depth 

sets a lower limit on the lowest sound 

frequency that will propagate (the 

‘‘cutoff frequency’’) at about one-quarter 

wavelength (Urick, 1983; Rogers and 

Cox, 1988). 

According to Buchanan et al. (2004), 

for the types of seismic airguns and 

arrays involved with the proposed 

program, the pathological (mortality) 

zone for fish would be expected to be 

within a few meters of the seismic 

source. Numerous other studies provide 

examples of no fish mortality upon 

exposure to seismic sources (Falk and 

Lawrence, 1973; Holliday et al., 1987; 

La Bella et al., 1996; Santulli et al., 

1999; McCauley et al., 2000a,b, 2003; 

Bjarti, 2002; Hassel et al. 2003; Popper 

et al., 2005). 

Physiological Effects – Physiological 

effects involve temporary and 

permanent primary and secondary stress 

responses. Cellular and/or biochemical 

responses of fish to acoustic stress such 

as changes in levels of enzymes and 

proteins could potentially affect fish 

populations by increasing mortality or 

reducing reproductive success. Primary 

and secondary stress responses of fish 

after exposure to seismic survey sound 

appear to be temporary in all studies 

done to date (Sverdrup et al., 1994; 

McCauley et al., 2000a,b). The periods 

necessary for the biochemical changes 

to return to normal are variable, and 

depend on numerous aspects of the 

biology of the species and of the sound 

stimulus (see Appendix D of L-DEO’s 

EA). 

Behavioral Effects – Behavioral effects 

include changes in the distribution, 

migration, mating, and catchability of 

fish populations. Studies investigating 

the possible effects of sound (including 

seismic survey sound) on fish behavior 

have been conducted on both uncaged 

and caged individuals (Chapman and 

Hawkins, 1969; Pearson et al., 1992; 

Santulli et al., 1999; Wardle et al., 2001; 

Hassel et al., 2003). Typically, in these 

studies fish exhibited a sharp ‘‘startle’’ 

response at the onset of a sound 

followed by habituation and a return to 

normal behavior after the sound ceased. 

There is general concern about 

potential adverse effects of seismic 

operations on fisheries, namely a 

potential reduction in the ‘‘catchability’’ 

of fish involved in fisheries. Although 

reduced catch rates have been observed 

in some marine fisheries during seismic 

testing, in a number of cases the 

findings are confounded by other 

sources of disturbance (Dalen and 

Raknes, 1985; Dalen and Knutsen, 1986; 

Lokkeborg, 1991; Skalski et al., 1992; 

Engas et al., 1996). In other airgun 

experiments, there was no change in 

catch per unit effort (CPUE) of fish 

when airgun pulses were emitted, 

particularly in the immediate vicinity of 

the seismic survey (Pickett et al., 1994; 

La Bella et al., 1996). For some species, 

reductions in catch may have resulted 

from a change in behavior of the fish, 

e.g., a change in vertical or horizontal 

distribution, as reported in Slotte et al. 

(2004). 

In general, any adverse effects on fish 

behavior or fisheries attributable to 


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Federal Register / Vol. 74, No. 88 / Friday, May 8, 2009 / Notices 21647 

seismic testing may depend on the 

species in question and the nature of the 

fishery (season, duration, fishing 

method). They may also depend on the 

age of the fish, its motivational state, its 

size, and numerous other factors that are 

difficult, if not impossible, to quantify at 

this point, given such limited data on 

effects of airguns on fish, particularly 

under realistic at-sea conditions. 

Potential Impacts on Invertebrates 

The existing body of information on 

the impacts of seismic survey sound on 

marine invertebrates is very limited. 

However, there is some unpublished 

and very limited evidence of the 

potential for adverse effects on 

invertebrates, thereby justifying further 

discussion and analysis of this issue. 

The three types of potential effects of 

exposure to seismic surveys on marine 

invertebrates are pathological, 

physiological, and behavioral. Based on 

the physical structure of their sensory 

organs, marine invertebrates appear to 

be specialized to respond to particle 

displacement components of an 

impinging sound field and not to the 

pressure component (Popper et al., 

2001; see also Appendix E of L-DEO’s 

EA). 

Pathological Effects – For the type of 

airgun array planned for the proposed 

program, the pathological (mortality) 

zone for crustaceans and cephalopods is 

expected to be within a few meters of 

the seismic source; however, very few 

specific data are available on levels of 

seismic signals that might damage these 

animals. This premise is based on the 

peak pressure and rise/decay time 

characteristics of seismic airgun arrays 

currently in use around the world. Some 

studies have suggested that seismic 

survey sound has a limited pathological 

impact on early developmental stages of 

crustaceans (Pearson et al., 1994; 

Christian et al., 2003; DFO, 2004). 

However, the impacts appear to be 

either temporary or insignificant 

compared to what occurs under natural 

conditions. Controlled field experiments 

on adult crustaceans (Christian et al., 

2003, 2004; DFO, 2004) and adult 

cephalopods (McCauley et al., 2000a,b) 

exposed to seismic survey sound have 

not resulted in any significant 

pathological impacts on the animals. It 

has been suggested that exposure to 

commercial seismic survey activities 

has injured giant squid (Guerra et al., 

2004), but there is no evidence to 

support such claims. 

Benthic invertebrates in the Endeavor 

MPA are not expected to be affected by 

seismic operations, as sound levels from 

the airguns will diminish dramatically 

by the time the sound reaches the ocean 

floor at a depth of approximately 2250 

m (7382 ft). 

Negligible Impact Determination 

NMFS has preliminarily determined, 

provided that the aforementioned 

mitigation and monitoring measures are 

implemented, that the impact of 

conducting a seismic program in the 

northeast Pacific Ocean may result, at 

worst, in a temporary modification in 

behavior and/or low-level physiological 

effects (Level B Harassment) of small 

numbers of certain species of marine 

mammals. While behavioral and 

avoidance reactions may be made by 

these species in response to the 

resultant noise from the airguns, these 

behavioral changes are expected to have 

a negligible impact on the affected 

species and stocks of marine mammals. 

While the number of potential 

incidental harassment takes will depend 

on the distribution and abundance of 

marine mammals in the area of seismic 

operations, the number of potential 

harassment takings is estimated to be 

relatively small in light of the 

population size (see Table 2). NMFS 

anticipates the actual take of individuals 

to be lower than the numbers depicted 

in the table, because those numbers do 

not reflect either the implementation of 

the mitigation numbers or the fact that 

some animals will avoid the sound at 

levels lower than those expected to 

result in harassment. Additionally, 

mitigation measures require that the 

Langseth avoid any areas where marine 

mammals are concentrated. 

In addition, no take by death and/or 

serious injury is anticipated, and the 

potential for temporary or permanent 

hearing impairment will be avoided 

through the incorporation of the 

required mitigation measures described 

in this document. This conclusion is 

supported by: (1) the likelihood that, 

given sufficient notice through slow 

ship speed and ramp-up of the seismic 

array, marine mammals are expected to 

move away from a noise source that it 

is annoying prior to its becoming 

potentially injurious; (2) TTS is unlikely 

to occur, especially in odontocetes, until 

levels above 180 dB re 1 μPa (rms) are 

reached; (3) the fact that injurious levels 

of sound are only likely very close to the 

vessel; and (4) the monitoring program 

developed to avoid injury will be 

sufficient to detect (using visual 

detection and PAM), with reasonable 

certainty, all marine mammals within or 

entering the identified safety zones. 

Endangered Species Act (ESA) 

Under section 7 of the ESA, the 

National Science Foundation (NSF) has 

begun consultation on this proposed 

seismic survey. NMFS will also consult 

internally on the issuance of an IHA 

under section 101(a)(5)(D) of the MMPA 

for this activity. Consultation will be 

concluded prior to a determination on 

the issuance of an IHA. 

National Environmental Policy Act 

(NEPA) 

On September 22, 2005 (70 FR 55630), 

NSF published a notice of intent to 

prepare a Programmatic Environmental 

Impact Statement/Overseas 

Environmental Impact Statement (EIS/ 

OES) to evaluate the potential 

environmental impacts associated with 

the use of seismic sources in support of 

NSF-funded research by U.S. academic 

scientists. NMFS agreed to be a 

cooperating agency in the preparation of 

the EIS/OEIS. This EIS/OEIS has not 

been completed. Therefore, in order to 

meet NSF’s and NMFS’ NEPA 

requirements for the proposed activity 

and issuance of an IHA to L-DEO, the 

NSF has prepared an Environmental 

Assessment of a Marine Geophysical 

Survey by the Langseth in the northeast 

Pacific Ocean in the Endeavor MPA. 

NMFS is reviEwing that document and 

will either adopt NSF’s EA or conduct 

a separate NEPA analysis, as necessary, 

prior to making a determination of the 

issuance of the IHA. NMFS has posted 

NSF’s EA on its website at http:// 

www.nmfs.noaa.gov/pr/permits/ 

incidental.htm#applications. 

Preliminary Conclusions 

Based on the preceding information, 

and provided that the proposed 

mitigation and monitoring are 

incorporated, NMFS has preliminarily 

concluded that the proposed activity 

will incidentally take, by level B 

behavioral harassment only, small 

numbers of marine mammals. There is 

no subsistence harvest of marine 

mammals in the proposed research area; 

therefore, there will be no impact of the 

activity on the availability of the species 

or stocks of marine mammals for 

subsistence uses. No take by Level A 

harassment (injury) or death is 

anticipated and harassment takes 

should be at the lowest level practicable 

due to incorporation of the mitigation 

measures proposed in this document. 

Proposed Authorization 

NMFS proposes to issue an IHA to LDEO for a marine seismic survey in the 

northeast Pacific Ocean during August - 

October 2009, provided the previously 

mentioned mitigation, monitoring, and 

reporting requirements are incorporated. 


hsrobinson on PROD1PC76 with NOTICES
21648 Federal Register / Vol. 74, No. 88 / Friday, May 8, 2009 / Notices 

Dated: May 4, 2009. 

Helen M. Golde, 

Deputy Director, Office of Protected 

Resources, National Marine Fisheries Service. 

[FR Doc. E9–10821 Filed 5–7–09; 8:45 am] 

BILLING CODE 3510–22–S 

DEPARTMENT OF COMMERCE 

National Oceanic and Atmospheric 

Administration 

RIN 0648–XO92 

Notice of Availability of the Marine 

Mammal Health and Stranding 

Response Program Record of Decision 

AGENCY: National Marine Fisheries 

Service (NMFS), National Oceanic and 

Atmospheric Administration (NOAA), 

Commerce. 

ACTION: Notice of Availability (NOA) of 

Record of Decision. 

SUMMARY: The National Marine 

Fisheries Service (NMFS) announces the 

availability of the Record of Decision 

(ROD) for the Marine Mammal Health 

and Stranding Response Program 

(MMHSRP). This ROD announces 

NMFS’ decisions for implementing the 

MMHSRP. Pursuant to the National 

Environmental Policy Act (NEPA) and 

implementing regulations, NMFS 

prepared a Programmatic Environmental 

Impact Statement (PEIS) that evaluated 

the potential environmental and 

socioeconomic effects associated with 

alternatives for the MMHSRP’s 

activities. 

ADDRESSES: Comments or questions 

regarding the ROD can be sent to David 

Cottingham, Chief, Marine Mammal and 

Sea Turtle Division, Office of Protected 

Resources, National Marine Fisheries 

Service, 1315 East-West Highway, Room 

13635, Silver Spring, MD 20910. 

FOR FURTHER INFORMATION CONTACT: 

Sarah Howlett, Fishery Biologist, NMFS, 

at (301) 713–2322; facsimile at (301) 

427–2522. 

SUPPLEMENTARY INFORMATION: A copy of 

the ROD and the Final PEIS are 

available at: http://www.nmfs.noaa.gov/ 

pr/health/eis.htm. 

Dated: May 1, 2009. 

Katy M. Vincent, 

Acting Deputy Director, Office of Protected 

Resources, National Marine Fisheries Service. 

[FR Doc. E9–10676 Filed 5–7–09; 8:45 am] 

BILLING CODE S 

DEPARTMENT OF COMMERCE 

National Oceanic and Atmospheric 

Administration 

RIN 0648–XO84 

Small Takes of Marine Mammals 

Incidental to Specified Activities; 

Taking Marine Mammals Incidental to 

Construction and Operation of a 

Liquefied Natural Gas Facility off 

Massachusetts 

AGENCY: National Marine Fisheries 

Service (NMFS), National Oceanic and 

Atmospheric Administration (NOAA), 

Commerce. 

ACTION: Notice; proposed incidental 

harassment authorization; request for 

comments and information. 

SUMMARY: NMFS received an 

application from Neptune LNG, L.L.C. 

(Neptune) for take of marine mammals, 

by Level B harassment, incidental to 

construction and operation of an 

offshore liquefied natural gas (LNG) 

facility in Massachusetts Bay. Under the 

Marine Mammal Protection Act 

(MMPA), NMFS is requesting comments 

on its proposal to issue an incidental 

harassment authorization (IHA) to 

Neptune to incidentally take, by 

harassment, small numbers of several 

species of marine mammals during 

construction and operations of the LNG 

facility for a period of 1 year. 

DATES: Comments and information must 

be received no later than June 8, 2009. 

ADDRESSES: Written comments on the 

application should be addressed to: P. 

Michael Payne, Chief, Permits, 

Conservation, and Education Division, 

Office of Protected Resources, National 

Marine Fisheries Service, 1315 EastWest Highway, Silver Spring, MD 

20910–3225. The mailbox address for 

providing email comments is PR1.0648– 

XO84@noaa.gov. Comments sent via 

email, including all attachments, must 

not exceed a 10–megabyte file size. A 

copy of the application containing a list 

of references used in this document may 

be obtained by writing to this address, 

by telephoning the contact listed below 

(see FOR FURTHER INFORMATION CONTACT) 

or online at: http://www.nmfs.noaa.gov/ 

pr/permits/incidental.htm#applications. 

Documents cited in this notice may be 

viewed, by appointment, during regular 

business hours, at the aforementioned 

address. 

Instructions: All comments received 

are a part of the public record and will 

generally be posted to http:// 

www.nmfs.noaa.gov/pr/permits/ 

incidental.htm#applications without 

change. All Personal Identifying 

Information (for example, name, 

address, etc.) voluntarily submitted by 

the commenter may be publicly 

accessible. Do not submit Confidential 

Business Information or otherwise 

sensitive or protected information. 

The Maritime Administration 

(MARAD) and U.S. Coast Guard (USCG) 

Final Environmental Impact Statement 

(Final EIS) on the Neptune LNG 

Deepwater Port License Application is 

available for viewing at http:// 

www.regulations.gov by entering the 

search words ‘‘Neptune LNG.’’ 

FOR FURTHER INFORMATION CONTACT: 

Candace Nachman, Office of Protected 

Resources, NMFS, (301) 713–2289 ext. 

156. 

SUPPLEMENTARY INFORMATION: 

Background 

Sections 101(a)(5)(A) and (D) of the 

MMPA (16 U.S.C. 1361 et seq.) direct 

the Secretary of Commerce to allow, 

upon request, the incidental, but not 

intentional taking of small numbers of 

marine mammals by U.S. citizens who 

engage in a specified activity (other than 

commercial fishing) within a specified 

geographical region if certain findings 

are made and either regulations are 

issued or, if the taking is limited to 

harassment, notice of a proposed 

authorization is provided to the public 

for review. 

Authorization for incidental takings 

may 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 taking 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 

establishes an expedited process by 

which citizens of the U.S. can apply for 

an authorization to incidentally take 

small numbers of marine mammals by 

harassment. Except for certain 

categories of 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, 


hsrobinson on PROD1PC76 with NOTICES