Federal Register / Vol. 76, No. 63 / Friday, April 1, 2011 / Notices 18167 

www.nist.gov/tip/. Individuals and 

representatives of organizations who 

would like to offer comments and 

suggestions related to the Board’s affairs 

are invited to request a place on the 

agenda. On May 18, 2011, 

approximately one-half hour will be 

reserved for public comments, and 

speaking times will be assigned on a 

first-come, first-serve basis. The amount 

of time per speaker will be determined 

by the number of requests received, but 

is likely to be about three minutes each. 

Questions from the public will not be 

considered during this period. Speakers 

who wish to expand upon their oral 

statements, those who had wished to 

speak but could not be accommodated 

on the agenda, and those who were 

unable to attend in person are invited to 

submit written statements to the TIP 

Advisory Board, National Institute of 

Standards and Technology, 100 Bureau 

Drive, MS 4700, Gaithersburg, Maryland 

20899, via fax at (301) 975–4032, or 

electronically by e-mail to 

(lorel.wisniewski@nist.gov). All visitors 

to the National Institute of Standards 

and Technology site will have to preregister to be admitted. Please submit 

your name, time of arrival, e-mail 

address and phone number to Rene 

Cesaro no later than Friday, May 13, 

2011, and she will provide you with 

instructions for admittance. Ms. 

Cesaro’s e-mail address is 

rene.cesaro@nist.gov and her phone 

number is (301) 975–2162. 

Dated: March 25, 2011. 

Charles H. Romine, 

Acting Associate Director for Laboratory 

Programs. 

[FR Doc. 2011–7756 Filed 3–31–11; 8:45 am] 

BILLING CODE 3510–13–P 

DEPARTMENT OF COMMERCE 

National Oceanic and Atmospheric 

Administration 

RIN 0648–XA255 

Takes of Marine Mammals Incidental to 

Specified Activities; Marine 

Geophysical Survey in the Central Gulf 

of Alaska, June, 2011 

AGENCY: National Marine Fisheries 

Service (NMFS), National Oceanic and 

Atmospheric Administration (NOAA), 

Commerce. 

ACTION: Notice; proposed Incidental 

Harassment Authorization; request for 

comments. 

SUMMARY: NMFS has received an 

application from the U.S. Geological 

Survey (USGS) for an Incidental 

Harassment Authorization (IHA) to take 

marine mammals, by harassment, 

incidental to conducting a marine 

geophysical survey in the central Gulf of 

Alaska (GOA), June, 2011. Pursuant to 

the Marine Mammal Protection Act 

(MMPA), NMFS is requesting comments 

on its proposal to issue an IHA to USGS 

to incidentally harass, by Level B 

harassment only, 9 species of marine 

mammals during the specified activity. 

DATES: Comments and information must 

be received no later than May 2, 2011. 

ADDRESSES: Comments on the 

application should be addressed to P. 

Michael Payne, Chief, Permits, 

Conservation and Education Division, 

Office of Protected Resources, National 

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

20910. The mailbox address for 

providing email comments is 

ITP.Goldstein@noaa.gov. NMFS is not 

responsible for e-mail comments sent to 

addresses other than the one provided 

here. 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 above address, telephoning the 

contact listed here (see FOR FURTHER

INFORMATION CONTACT) or visiting the 

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

pr/permits/incidental.htm#applications. 

The U.S. Geological Survey (USGS), 

which is providing funding for the 

proposed action, has prepared a draft 

‘‘Environmental Assessment (EA) of a 

Marine Geophysical Survey by the R/V 

Marcus G. Langseth in the Central Gulf 

of Alaska, June 2011,’’ prepared by LGL 

Ltd., Environmental Research 

Associates (LGL), on behalf of USGS, 

which is also available at the same 

internet address. Documents cited in 

this notice may be viewed, by 

appointment, during regular business 

hours, at the aforementioned address. 

FOR FURTHER INFORMATION CONTACT: 

Howard Goldstein or Jolie Harrison, 

Office of Protected Resources, NMFS, 

(301) 713–2289, ext. 172. 

SUPPLEMENTARY INFORMATION: 

Background 

Section 101(a)(5)(D) of the MMPA (16 

U.S.C. 1371(a)(5)(D)) directs the 

Secretary of Commerce (Secretary) to 

authorize, upon request, the incidental, 

but not intentional, taking of small 

numbers of marine mammals of a 

species or population stock, 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, if the 

taking is limited to harassment, a notice 

of a proposed authorization is provided 

to the public for review. 

Authorization for the incidental 

taking of small numbers of marine 

mammals shall be granted if NMFS 

finds that the taking will have a 

negligible impact on the species or 

stock(s), and will not have an 

unmitigable adverse impact on the 

availability of the species or stock(s) for 

subsistence uses (where relevant). The 

authorization must set forth the 

permissible methods of taking, other 

means of effecting the least practicable 

adverse impact on the species or stock 

and its habitat, and requirements 

pertaining to the mitigation, monitoring 

and reporting of such takings. 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. 

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

establishes a 45-day time limit for 

NMFS’ review of an application 

followed by a 30-day public notice and 

comment period on any proposed 

authorizations for the incidental 

harassment of small numbers of marine 

mammals. Within 45 days of the close 

of the public comment period, NMFS 

must either issue or deny the 

authorization. 

Except with respect to certain 

activities not pertinent here, the MMPA 

defines ‘‘harassment’’ as: 

any act of pursuit, torment, or annoyance 

which (i) has the potential to injure a marine 

mammal or marine mammal stock in the wild 

[Level A harassment]; or (ii) has the potential 

to disturb a marine mammal or marine 

mammal stock in the wild by causing 

disruption of behavioral patterns, including, 

but not limited to, migration, breathing, 

nursing, breeding, feeding, or sheltering 

[Level B harassment]. 

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18168 Federal Register / Vol. 76, No. 63 / Friday, April 1, 2011 / Notices 

Summary of Request 

NMFS received an application on 

January 21, 2011, from USGS for the 

taking by harassment, of marine 

mammals, incidental to conducting a 

marine geophysical survey in the central 

GOA within the U.S. Exclusive 

Economic Zone (EEZ) and adjacent 

international waters in depths from 

approximately 2,000 meters (m) (6,561.7 

feet [ft]) to greater than 6,000 m (19,685 

ft). USGS plans to conduct the proposed 

survey from approximately June 5 to 25, 

2011. 

USGS plans to use one source vessel, 

the R/V Marcus G. Langseth (Langseth) 

and a seismic airgun array to collect 

seismic reflection and refraction profiles 

to be used to delineate the U.S. 

Extended Continental Shelf (ECS) in the 

GOA. In addition to the proposed 

operations of the seismic airgun array, 

USGS intends to operate a multibeam 

echosounder (MBES) and a sub-bottom 

profiler (SBP) continuously throughout 

the survey. 

Acoustic stimuli (i.e., increased 

underwater sound) generated during the 

operation of the seismic airgun array 

may have the potential to cause a shortterm behavioral disturbance for marine 

mammals in the survey area. This is the 

principal means of marine mammal 

taking associated with these activities 

and USGS has requested an 

authorization to take 9 species of marine 

mammals by Level B harassment. Take 

is not expected to result from the use of 

the MBES or SBP, for reasons discussed 

in this notice; nor is take expected to 

result from collision with the vessel 

because it is a single vessel moving at 

a relatively slow speed during seismic 

acquisition within the survey, for a 

relatively short period of time 

(approximately 21 days). It is likely that 

any marine mammal would be able to 

avoid the vessel. 

Description of the Specified Activity 

USGS’s proposed seismic survey in 

the central GOA is between 

approximately 200 to 650 kilometers 

(km) (108 to 351 nautical miles [nmi]) 

offshore in the area 53 to 57° North, 135 

to 148° West (see Figure 1 of the IHA 

application). Water depths in the survey 

area range from approximately 2,000 m 

(6,561.7 ft) to greater than 6,000 m 

(19,685 ft). The project is scheduled to 

occur from approximately June 5 to 25, 

2011. Some minor deviation from these 

dates is possible, depending on logistics 

and weather. The proposed seismic 

survey will collect seismic reflection 

and refraction profiles to be used to 

delineate the U.S. ECS in the GOA. The 

ECS is the region beyond 200 nmi where 

a nation can show that it satisfies the 

conditions of Article 76 of the United 

Nations Convention on the Law of the 

Sea. One of the conditions in Article 76 

is a function of sediment thickness. The 

seismic profiles are designed to identify 

the stratigraphic ‘‘basement’’ and to map 

the thickness of the overlying 

sediments. Acoustic velocities (required 

to convert measured travel times to true 

depth) will be measured directly using 

sonobuoys and ocean-bottom 

seismometers (OBSs), as well as by 

analysis of hydrophone streamer data. 

Acoustic velocity refers to the velocity 

of sound through sediments or crust. 

The survey will involve one source 

vessel, the Langseth. The Langseth will 

deploy an array of 36 airguns as an 

energy source. The receiving system 

will consist of one 8 km (4.3 nmi) long 

hydrophone streamer and/or five OBSs. 

As the airgun is towed along the survey 

lines, the hydrophone streamer will 

receive the returning acoustic signals 

and transfer the data to the on-board 

processing system. The OBSs record the 

returning acoustic signals internally for 

later analysis. 

The planned seismic survey (e.g., 

equipment testing, startup, line changes, 

repeat coverage of any areas, and 

equipment recovery) will consist of 

approximately 2,840 km (1,533.5 nmi) 

of transect lines in the central GOA 

survey area (see Figure 1 of the IHA 

application), with an additional 140 km 

(75.6 nmi) of turns. The array will be 

powered-down to one 40 in3 airgun 

during turns. All of the survey will take 

place in water deeper than 1,000 m 

(3,280.8 ft). A multi-channel seismic 

(MCS) survey using the hydrophone 

streamer will take place along 17 MCS 

profile lines and 2 OBS lines. Following 

the MCS survey, five OBSs will be 

deployed and a refraction survey will 

take place along one of the 11 lines. If 

time permits, an additional 340 km 

(183.6 nmi) contingency line will be 

added to the MCS survey. In addition to 

the operations of the airgun array, a 

Kongsberg EM 122 MBES and Knudsen 

320B SBP will also be operated from the 

Langseth continuously throughout the 

cruise. There will be additional seismic 

operations associated with equipment 

testing, start-up, and possible line 

changes or repeat coverage of any areas 

where initial data quality is substandard. In USGS’s calculations, 25% 

has been added for those additional 

operations. 

All planned geophysical data 

acquisition activities will be conducted 

by Lamont-Doherty Earth Observatory 

(L–DEO), the Langseth’s operator, with 

on-board assistance by the scientists 

who have proposed the study. The 

Principal Investigators are Drs. Jonathan 

R. Childs and Ginger Barth of the USGS. 

The vessel will be self-contained, and 

the crew will live aboard the vessel for 

the entire cruise. 

Vessel Specifications 

The Langseth, owned by the National 

Science Foundation, will tow the 36 

airgun array, as well as the hydrophone 

streamer, along predetermined lines. 

The Langseth will also deploy and 

retrieve the OBSs. When the Langseth is 

towing the airgun array and the 

hydrophone streamer, the turning rate of 

the vessel is limited to five degrees per 

minute. Thus, the maneuverability of 

the vessel is limited during operations 

with the streamer. 

The vessel has a length of 71.5 m (235 

ft); a beam of 17.0 m (56 ft); a maximum 

draft of 5.9 m (19 ft); and a gross 

tonnage of 3,834. The Langseth was 

designed as a seismic research vessel 

with a propulsion system designed to be 

as quiet as possible to avoid interference 

with the seismic signals emanating from 

the airgun array. The ship is powered by 

two 3,550 horsepower (hp) Bergen BRG– 

6 diesel engines which drive 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 Langseth’s 

operation speed during seismic 

acquisition is typically 7.4 to 9.3 km per 

hour (hr) (km/hr) (4 to 5 knots [kts]). 

When not towing seismic survey gear, 

the Langseth typically cruises at 18.5 

km/hr (10 kts). The Langseth has a range 

of 25,000 km (13,499 nmi) (the distance 

the vessel can travel without refueling). 

The vessel also has an observation 

tower from which protected species 

visual observers (PSVO) will watch for 

marine mammals before and during the 

proposed airgun operations. When 

stationed on the observation platform, 

the PSVO’s eye level will be 

approximately 21.5 m (71 ft) above sea 

level providing the PSVO an 

unobstructed view around the entire 

vessel. 

Acoustic Source Specifications 

Seismic Airguns 

The Langseth will deploy a 36 airgun 

array, with a total volume of 

approximately 6,600 cubic inches (in3). 

The airgun array will consist of a 

mixture of Bolt 1500LL and Bolt 

1900LLX airguns ranging in size from 40 

to 360 in3, with a firing pressure of 

1,900 pounds per square inch. The 

airguns will be configured as four 

identical linear arrays or ‘‘strings.’’ Each 

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Federal Register / Vol. 76, No. 63 / Friday, April 1, 2011 / Notices 18169 

string will have 10 airguns, the first and 

last airguns in the strings are spaced 16 

m (52 ft) apart. Of the 10 airguns, nine 

airguns in each string 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 area of 

approximately 24x16 m (78.7x52.5 ft) 

behind the Langseth and will be towed 

approximately 100 m (328 ft) behind the 

vessel. The shot interval will be 50 m 

(164 ft) or approximately 22 seconds (s) 

for the MCS survey and 150 m (492.1 ft) 

or approximately 66 s for the OBS 

refraction survey. The firing pressure of 

the array is 1,900 pounds per square 

inch (psi). During firing, a brief 

(approximately 0.1 s) pulse sound is 

emitted. The airguns will be silent 

during the intervening periods. The 

dominant frequency components range 

from two to 188 Hertz (Hz). 

The tow depth of the array will be 9 

m (29.5 ft) during OBS refraction and 

MCS surveys. Because the actual source 

is a distributed sound source (36 

airguns) rather than a single point 

source, the highest sound measurable at 

any location in the water will be less 

than the nominal source level. In 

addition, the effective source level for 

sound propagating in near-horizontal 

directions will be substantially lower 

than the nominal source level 

applicable to downward propagation 

because of the directional nature of the 

sound from the airgun array. 

Metrics Used in This Document 

This section includes a brief 

explanation of the sound measurements 

frequently used in the discussions of 

acoustic effects in this document. Sound 

pressure is the sound force per unit 

area, and is usually measured in 

micropascals (μPa), where 1 pascal (Pa) 

is the pressure resulting from a force of 

one newton exerted over an area of one 

square meter. Sound pressure level 

(SPL) is expressed as the ratio of a 

measured sound pressure and a 

reference level. The commonly used 

reference pressure level in underwater 

acoustics is 1 μPa, and the units for 

SPLs are dB re: 1 μPa. SPL (in decibels 

[dB]) = 20 log (pressure/reference 

pressure) 

SPL is an instantaneous measurement 

and can be expressed as the peak, the 

peak-peak (p-p), or the root mean square 

(rms). Root mean square, which is the 

square root of the arithmetic average of 

the squared instantaneous pressure 

values, is typically used in discussions 

of the effects of sounds on vertebrates 

and all references to SPL in this 

document refer to the root mean square 

unless otherwise noted. SPL does not 

take the duration of a sound into 

account. 

Characteristics of the Airgun Pulses 

Airguns function by venting highpressure air into the water which creates 

an air bubble. The pressure signature of 

an individual airgun consists of a sharp 

rise and then fall in pressure, followed 

by several positive and negative 

pressure excursions caused by the 

oscillation of the resulting air bubble. 

The oscillation of the air bubble 

transmits sounds downward through the 

seafloor and the amount of sound 

transmitted in the near horizontal 

directions is reduced. However, the 

airgun array also emits sounds that 

travel horizontally toward non-target 

areas. 

The nominal source levels of the 

airgun arrays used by USGS on the 

Langseth are 236 to 265 dB re 1 μPa (p– 

p) and the rms value for a given airgun 

pulse is typically 16 dB re 1 μPa lower 

than the peak-to-peak value. However, 

the difference between rms and peak or 

peak-to-peak values for a given pulse 

depends on the frequency content and 

duration of the pulse, among other 

factors. 

Accordingly, L–DEO has predicted 

the received sound levels in relation to 

distance and direction from the 36 

airgun array and the single Bolt 1900LL 

40 in3 airgun, which will be used during 

power-downs. A detailed description of 

L–DEO’s modeling for marine seismic 

source arrays for species mitigation is 

provided in Appendix A of USGS’s 

application. These are the nominal 

source levels applicable to downward 

propagation. The effective source levels 

for horizontal propagation are lower 

than those for downward propagation 

when the source consists of numerous 

airguns spaced apart from one another. 

Appendix B of USGS’s EA discusses 

the characteristics of the airgun pulses 

and marine mammals. NMFS refers the 

reviewers to the application and EA 

documents for additional information. 

Predicted Sound Levels for the Airguns 

Tolstoy et al., (2009) reported results 

for propagation measurements of pulses 

from the Langseth’s 36 airgun, 6,600 in3

array in shallow-water (approximately 

50 m [164 ft]) and deep-water depths 

(approximately 1,600 m [5,249 ft]) in the 

Gulf of Mexico in 2007 and 2008. L– 

DEO has used these reported empirical 

values to determine exclusion zones 

(EZs) for the 36 airgun array and the 

single airgun; to designate mitigation 

zones, and to estimate take for marine 

mammals. 

Results of the Gulf of Mexico 

calibration study (Tolstoy et al., 2009) 

showed that radii around the airguns for 

various received levels varied with 

water depth. The empirical data for 

deep water (greater than 1,000 m; 3,280 

ft) indicated that the L–DEO model (as 

applied to the Langseth’s 36 airgun 

array) overestimated the received sound 

levels at a given distance. 

Using the corrected measurements 

(array) or model (single airgun), Table 1 

(below) shows the distances at which 

three rms sound levels are expected to 

be received from the 36 airgun array and 

a single airgun. The 180 and 190 dB re 

1 μPa (rms) distances are the safety 

criteria as specified by NMFS (2000) 

and are applicable to cetaceans and 

pinnipeds, respectively. If marine 

mammals are detected within or about 

to enter the appropriate EZ, the airguns 

will be powered-down (or shut-down, if 

necessary) immediately. 

Table 1 (below) summarizes the 

predicted distances at which sound 

levels (160, 180, and 190 dB [rms]) are 

expected to be received from the 36 

airgun array and a single airgun 

operating in deep water depths. 

TABLE 1—MEASURED (ARRAY) OR PREDICTED (SINGLE AIRGUN) DISTANCES TO WHICH SOUND LEVELS ≥ 190, 180, AND

160 DB RE: 1 μPA (RMS) COULD BE RECEIVED IN WATER DEPTHS >1,000 M DURING THE PROPOSED SURVEY IN THE

CENTRAL GOA, JUNE 5 TO 25, 2011. 

Source and volume Water depth 

Predicted RMS distances (m) 

190 dB 180 dB 160 dB 

Single Bolt airgun (40 in3) ....................................................................... Deep > 1,000 m ............................. 12 40 385 

4 Strings 36 airguns (6,600 in3) .............................................................. Deep > 1,000 m ............................. 400 940 3,850 

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Along with the airgun operations, two 

additional acoustical data acquisition 

systems will be operated during the 

survey. The ocean floor will be mapped 

with the Kongsberg EM 122 MBES and 

a Knudsen 320B SBP. These sound 

sources will be operated continuously 

from the Langseth throughout the 

cruise. 

MBES 

The Langseth will operate a 

Kongsberg EM 122 MBES concurrently 

during airgun operations to map 

characteristics of the ocean floor. The 

hull-mounted MBES emits brief pulses 

of sound (also called a ping) (10.5 to 13, 

usually 12 kHz) in a fan-shaped beam 

that extends downward and to the sides 

of the ship. The transmitting beamwidth 

is 1° or 2° fore-aft and 150° athwartship 

and the maximum source level is 242 

dB re: 1 μPa. 

For deep-water operations, each ping 

consists of eight (in water greater than 

1,000 m) or four (less than 1,000 m) 

successive, fan-shaped transmissions, 

each ensonifying a sector that extends 1° 

fore-aft. Continuous-wave pulses 

increase from 2 to 15 milliseconds (ms) 

long in water depths up to 2,600 m 

(8,530.2 ft), and FM chirp pulses up to 

100 ms long are used in water greater 

than 2,600 m. The successive 

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

2 ms gaps between the pulses for 

successive sectors. 

SBP 

The Langseth will also operate a 

Knudsen 320B SBP continuously 

throughout the cruise simultaneously 

with the MBES to map and provide 

information about the sedimentary 

features and bottom topography. The 

beam is transmitted as a 27° cone, 

which is directed downward by a 3.5 

kHz transducer in the hull of the 

Langseth. The maximum output is 1,000 

watts (204 dB re 1 μPa), but in practice, 

the output varies with water depth. The 

pulse interval is one second, but a 

common mode of operation is to 

broadcast five pulses at one second 

intervals followed by a five second 

pause. 

NMFS expects that acoustic stimuli 

resulting from the proposed operation of 

the single airgun or the 36 airgun array 

has the potential to harass marine 

mammals, incidental to the conduct of 

the proposed seismic survey. NMFS 

expects these disturbances to be 

temporary and 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. 

NMFS does not expect that the 

movement of the Langseth, during the 

conduct of the seismic survey, has the 

potential to harass marine mammals 

because of the relatively slow operation 

speed of the vessel (4.6 knots [kts]; 8.5 

km/hr; 5.3 mph) during seismic 

acquisition. 

Description of the Proposed Dates, 

Duration, and Specified Geographic 

Region 

The survey will occur in the central 

GOA, between approximately 200 and 

650 km offshore, in the area 53 to 57° 

North, 135 to 148° West. The seismic 

survey will take place in water depths 

of 2,000 to greater than 6,000 m. The 

exact dates of the activities depend on 

logistics and weather conditions. The 

Langseth will depart from Dutch Harbor, 

Alaska on June 5, 2011, and return there 

on June 25, 2011. Seismic operations 

will be carried out for an estimated 12 

to 14 days. 

Description of the Marine Mammals in 

the Area of the Proposed Specified 

Activity 

Twenty-five marine mammal species 

(18 cetacean, 6 pinniped, and the sea 

otter) are known to or could occur in the 

GOA. Several of these species are listed 

as endangered under the U.S. 

Endangered Species Act of 1973 (ESA; 

16 U.S.C. 1531 et seq.), including the 

North Pacific right whale (Eubalaena 

japonica), humpback (Megaptera 

novaeangliae), sei (Balaenoptera 

borealis), fin (Balaenoptera physalus), 

blue (Balaenoptera musculus), and 

sperm (Physeter macrocephalus) 

whales, as well as the Cook Inlet 

distinct population segment (DPS) of 

beluga whales (Dephinapterus leucas) 

and the western stock of Steller sea 

lions (Eumetopias jubatus). The eastern 

stock of Steller sea lions is listed as 

threatened, as is the southwest Alaska 

DPS of the sea otter (Enhydra lutris). 

The marine mammals that occur in 

the proposed survey area belong to four 

taxonomic groups: odontocetes (toothed 

cetaceans, such as dolphins), mysticetes 

(baleen whales), pinnipeds (seals, sea 

lions, and walrus), and fissipeds (sea 

otter). Cetaceans and pinnipeds are the 

subject of the IHA application to NMFS. 

Walrus sightings are rare in the GOA. 

Sea otters generally inhabit nearshore 

areas inside the 40 m (131.2 ft) depth 

contour (Riedman and Estes, 1990) and 

likely would not be encountered in the 

deep, offshore waters of the study area. 

The sea otter and Pacific walrus are two 

marine mammal species mentioned in 

this document that are managed by the 

U.S. Fish and Wildlife Service (USFWS) 

and are not considered further in this 

analysis; all others are managed by 

NMFS. Coastal cetacean species (gray 

whales, beluga whales, and harbor 

porpoises) and pinniped species 

(California sea lions and harbor seals) 

likely would not be encountered in the 

deep, offshore waters of the survey area. 

Table 2 (below) presents information 

on the abundance, distribution, 

population status, conservation status, 

and density of the marine mammals that 

may occur in the proposed survey area 

during June, 2011. 

BILLING CODE 3510–22–P 

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Refer to Section III of USGS’s 

application for detailed information 

regarding the abundance and 

distribution, population status, and life 

history and behavior of these species 

and their occurrence in the proposed 

project area. The application also 

presents how USGS calculated the 

estimated densities for the marine 

mammals in the proposed survey area. 

NMFS has reviewed these data and 

determined them to be the best available 

scientific information for the purposes 

of the proposed IHA. 

Potential Effects on Marine Mammals 

Acoustic stimuli generated by the 

operation of the airguns, which 

introduce sound into the marine 

environment, may have the potential to 

cause Level B harassment of marine 

mammals in the proposed survey area. 

The effects of sounds from airgun 

operations 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 proposed project 

would result in any cases of temporary 

or permanent hearing impairment, or 

any significant non-auditory physical or 

physiological effects. Based on the 

available data and studies described 

here, some behavioral disturbance is 

expected, but NMFS expects the 

disturbance to be localized and shortterm. 

Tolerance to Sound 

Studies on marine mammals’ 

tolerance to sound in the natural 

environment are relatively rare. 

Richardson et al. (1995) defines 

tolerance as the occurrence of marine 

mammals in areas where they are 

exposed to human activities or manmade noise. In many cases, tolerance 

develops by the animal habituating to 

the stimulus (i.e., the gradual waning of 

responses to a repeated or ongoing 

stimulus) (Richardson, et al., 1995; 

Thorpe, 1963), but because of ecological 

or physiological requirements, many 

marine animals may need to remain in 

areas where they are exposed to chronic 

stimuli (Richardson, et al., 1995). 

Numerous studies have shown that 

pulsed sounds from airguns are often 

readily detectable in the water at 

distances of many kilometers. Malme et 

al., (1985) studied the responses of 

humpback whales on their summer 

feeding grounds in southeast Alaska to 

seismic pulses from a airgun with a total 

volume of 100 in3. They noted that the 

whales did not exhibit persistent 

avoidance when exposed to the airgun 

and concluded that there was no clear 

evidence of avoidance, despite the 

possibility of subtle effects, at received 

levels up to 172 dB re 1 μPa. 

Weir (2008) observed marine mammal 

responses to seismic pulses from a 24 

airgun array firing a total volume of 

either 5,085 in3 or 3,147 in3 in Angolan 

waters between August 2004 and May 

2005. She recorded a total of 207 

sightings of humpback whales (n = 66), 

sperm whales (n = 124), and Atlantic 

spotted dolphins (n = 17) and reported 

that there were no significant 

differences in encounter rates 

(sightings/hr) for humpback and sperm 

whales according to the airgun array’s 

operational status (i.e., active versus 

silent). 

Masking of Natural Sounds 

The term masking refers to the 

inability of a subject to recognize the 

occurrence of an acoustic stimulus as a 

result of the interference of another 

acoustic stimulus (Clark et al., 2009). 

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. 

Because of the intermittent nature and 

low duty cycle of seismic airgun pulses, 

animals can emit and receive sounds in 

the relatively quiet intervals between 

pulses. However, in some situations, 

reverberation occurs for much or the 

entire 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; and 

Dunn and Hernandez, 2009). However, 

Clark and Gagnon (2006) reported that 

fin whales in the northeast Pacific 

Ocean went silent for an extended 

period starting soon after the onset of a 

seismic survey in the area. Similarly, 

there has been one report that sperm 

whales ceased calling when exposed to 


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pulses from a very distant seismic ship 

(Bowles et al., 1994). However, more 

recent studies found that they continued 

calling in the presence of seismic pulses 

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

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

and Jochens et al., 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; and 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, NMFS expects the masking 

effects of seismic pulses to be minor, 

given the normally intermittent nature 

of seismic pulses. Refer to Appendix B 

(4) of USGS’s EA for a more detailed 

discussion of masking effects on marine 

mammals. 

Behavioral Disturbance 

Disturbance includes a variety of 

effects, including subtle to conspicuous 

changes in behavior, movement, and 

displacement. Reactions to sound, if 

any, depend on species, state of 

maturity, experience, current activity, 

reproductive state, time of day, and 

many other factors (Richardson et al., 

1995; Wartzok et al., 2004; Southall et 

al., 2007; Weilgart, 2007). If a marine 

mammal does react briefly to an 

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/or 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. Scientists 

have conducted detailed studies on 

humpback, gray, bowhead (Balaena 

mysticetus), and sperm whales. Less 

detailed data are available for some 

other species of baleen whales, small 

toothed whales, and sea otters, but for 

many species there are no data on 

responses to marine seismic surveys. 

Baleen Whales—Baleen whales 

generally tend to avoid operating 

airguns, but avoidance radii are quite 

variable (reviewed in Richardson et al., 

1995). Whales are often reported to 

show no overt reactions to pulses from 

large arrays of airguns at distances 

beyond a few kms, even though the 

airgun pulses remain well above 

ambient noise levels out to much longer 

distances. However, as reviewed in 

Appendix B (5) of USGS’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 

(Richardson, et al., 1995). 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 to 170 dB re 1 μPa (rms) seem to 

cause obvious avoidance behavior in a 

substantial fraction of the animals 

exposed (Malme et al., 1986, 1988; 

Richardson et al., 1995). In many areas, 

seismic pulses from large arrays of 

airguns diminish to those levels at 

distances ranging from four to 15 km 

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 (5) of 

USGS’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 to 170 dB 

re 1 μPa (rms). 

McCauley et al. (1998, 2000a) studied 

the responses of humpback whales off 

western Australia to a full-scale seismic 

survey with a 16 airgun array (2,678 in3) 

and to a single airgun (20 in3) with 

source level of 227 dB re 1 μPa (p–p). 

In the 1998 study, they documented that 

avoidance reactions began at five to 

eight km from the array, and that those 

reactions kept most pods approximately 

three to four km from the operating 

seismic boat. In the 2000 study, they 

noted localized displacement during 

migration of four to five km by traveling 

pods and seven to 12 km 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 for 

humpback pods containing females, and 

at the mean closest point of approach 

distance the received level was 143 dB 

re 1 μPa. The initial avoidance response 

generally occurred at distances of five to 

eight km from the airgun array and two 

km from the single airgun. However, 

some individual humpback whales, 

especially males, approached within 

distances of 100 to 400 m (328 to 1,312 

ft), where the maximum received level 

was 179 dB re 1 μPa. 

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). 

Some humpbacks seemed ‘‘startled’’ at 

received levels of 150 to 169 dB re 1 

μPa. Malme et al. (1985) concluded that 

there was no clear evidence of 

avoidance, despite the possibility of 

subtle effects, at received levels up to 

172 dB re 1 μPa (rms). 

Studies have 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 versus 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 to 30 km from a 

medium-sized airgun source at received 

sound levels of around 120 to 130 dB re 

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

al., 1999; see Appendix B (5) of USGS’s 

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 

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sensitive to seismic sources. 

Nonetheless, subtle but statistically 

significant changes in surfacingrespiration-dive cycles were evident 

upon statistical analysis (Richardson et 

al., 1986). In the summer, bowheads 

typically begin to show avoidance 

reactions at received levels of about 152 

to 178 dB re 1 μPa (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 

1 μPa. 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 seen in areas 

ensonified by airgun pulses (Stone, 

2003; MacLean and Haley, 2004; Stone 

and Tasker, 2006), and calls from blue 

and fin whales have been localized in 

areas with airgun operations (e.g., 

McDonald et al., 1995; Dunn and 

Hernandez, 2009). 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 

of Nova Scotia, Moulton and Miller 

(2005) found little difference in sighting 

rates (after accounting for water depth) 

and initial sighting distances of 

balaenopterid whales when airguns 

were operating vs. silent. However, 

there were indications that these whales 

were more likely to be moving away 

when seen during airgun operations. 

Similarly, ship-based monitoring 

studies of blue, fin, sei and minke 

whales offshore of Newfoundland 

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

differences in sighting rates and swim 

directions during seismic versus 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; Allen and Angliss, 2010). 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; Allen and 

Angliss, 2010). 

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 USGS’s EA have been 

reported for toothed whales. However, 

there are recent systematic studies on 

sperm whales (e.g., Gordon et al., 2006; 

Madsen et al., 2006; Winsor and Mate, 

2006; Jochens et al., 2008; Miller et al., 

2009). 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; Hauser et al., 

2008; Holst and Smultea, 2008; Weir, 

2008; Barkaszi et al., 2009; Richardson 

et al., 2009). 

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; 

Richardson et al., 2009; see also 

Barkaszi et al., 2009). 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 one km less, 

and some individuals show no apparent 

avoidance. The beluga whale 

(Delphinapterus leucas) is a species that 

(at least at times) shows long-distance 

avoidance of seismic vessels. Aerial 

surveys conducted in the southeastern 

Beaufort Sea during summer found that 

sighting rates of beluga whales were 

significantly lower at distances 10 to 20 

km compared with 20 to 30 km 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 

truncatus) 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 show 

stronger avoidance of seismic operations 

than do Dall’s porpoises (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 

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the whales do not show strong 

avoidance, and they continue to call 

(see Appendix B of USGS’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., 2008; Miller et al., 2009; 

Tyack, 2009). 

There are almost no specific data on 

the behavioral reactions of beaked 

whales to seismic surveys. However, 

some northern bottlenose whales 

(Hyperoodon ampullatus) remained in 

the general area and continued to 

produce high-frequency clicks when 

exposed to sound pulses from distant 

seismic surveys (Gosselin and Lawson, 

2004; 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). Based on a single 

observation, Aguilar-Soto et al. (2006) 

suggested that foraging efficiency of 

Cuvier’s beaked whales may be reduced 

by close approach of vessels. 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 Stranding and 

Mortality section in this notice). These 

strandings are apparently 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. Seismic 

survey sounds are quite different from 

those of the sonar in operation during 

the above-cited incidents. 

Odontocete reactions to large arrays of 

airguns are variable and, at least for 

delphinids and Dall’s porpoises, seem to 

be confined to a smaller radius than has 

been observed for the more responsive 

of the mysticetes, belugas, and harbor 

porpoises (Appendix B of USGS’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 of USGS’s EA. 

In the Beaufort Sea, some ringed seals 

avoided an area of 100 m to (at most) a 

few hundred meters around seismic 

vessels, but many seals remained within 

100 to 200 m (328 to 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 and California sea lions 

tended to be larger when airguns were 

operating (Calambokidis and Osmek, 

1998). Previous telemetry work suggests 

that avoidance and other behavioral 

reactions may be stronger than evident 

to date from visual studies (Thompson 

et al., 1998). 

Hearing Impairment and Other Physical 

Effects 

Exposure to high intensity sound for 

a sufficient duration may result in 

auditory effects such as a noise-induced 

threshold shift—an increase in the 

auditory threshold after exposure to 

noise (Finneran, Carder, Schlundt, and 

Ridgway, 2005). Factors that influence 

the amount of threshold shift include 

the amplitude, duration, frequency 

content, temporal pattern, and energy 

distribution of noise exposure. The 

magnitude of hearing threshold shift 

normally decreases over time following 

cessation of the noise exposure. The 

amount of threshold shift just after 

exposure is called the initial threshold 

shift. If the threshold shift eventually 

returns to zero (i.e., the threshold 

returns to the pre-exposure value), it is 

called temporary threshold shift (TTS) 

(Southall et al., 2007). 

Researchers have studied TTS in 

certain captive odontocetes and 

pinnipeds exposed to strong sounds 

(reviewed in Southall et al., 2007). 

However, there has been no specific 

documentation of TTS let alone 

permanent hearing damage, i.e., 

permanent threshold shift (PTS), in freeranging marine mammals exposed to 

sequences of airgun pulses during 

realistic field conditions. 

Temporary Threshold Shift—TTS is 

the mildest form of hearing impairment 

that can occur during exposure to a 

strong sound (Kryter, 1985). While 

experiencing TTS, the hearing threshold 

rises and a sound must be stronger in 

order to be heard. At least in terrestrial 

mammals, TTS can last from minutes or 

hours to (in cases of strong TTS) days. 

For sound exposures at or somewhat 

above the TTS threshold, hearing 

sensitivity in both terrestrial and marine 

mammals recovers rapidly after 

exposure to the noise ends. Few data on 

sound levels and durations necessary to 

elicit mild TTS have been obtained for 

marine mammals, and none of the 

published data concern TTS elicited by 

exposure to multiple pulses of sound. 

Available data on TTS in marine 

mammals are summarized in Southall et 

al. (2007). Table 1 (above) presents the 

distances from the Langseth’s airguns at 

which the received energy level (per 

pulse, flat-weighted) would be expected 

to be greater than or equal to 180 dB re 

1 μPa (rms). 

To avoid the potential for injury, 

NMFS (1995, 2000) concluded that 

cetaceans should not be exposed to 

pulsed underwater noise at received 

levels exceeding 180 dB re 1 μPa (rms). 

NMFS believes that to avoid the 

potential for permanent physiological 

damage (Level A harassment), cetaceans 

should not be exposed to pulsed 

underwater noise at received levels 

exceeding 180 dB re 1 μPa (rms). The 

180 dB level is a shutdown criterion 

applicable to cetaceans, as specified by 

NMFS (2000); these levels were used to 

establish the EZs. NMFS also assumes 

that cetaceans exposed to levels 

exceeding 160 dB re 1 μPa (rms) may 

experience Level B harassment. 

Researchers have derived TTS 

information for odontocetes from 

studies on the bottlenose dolphin and 

beluga. For the one harbor porpoise 

tested, the received level of airgun 

sound that elicited onset of TTS was 

lower (Lucke et al., 2009). If these 

results from a single animal are 

representative, it is inappropriate to 

assume that onset of TTS occurs at 

similar received levels in all 

odontocetes (cf. Southall et al., 2007). 

Some cetaceans apparently can incur 

TTS at considerably lower sound 

exposures than are necessary to elicit 

TTS in the beluga or bottlenose dolphin. 

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 

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TTS onset may also be higher in baleen 

whales (Southall et al., 2007). For this 

proposed study, USGS expects no cases 

of TTS given: (1) The low abundance of 

baleen whales in the planned study area 

at the time of the survey; and (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. 

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 approximately 181 to 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 are likely to be higher 

(Kastak et al., 2005). 

Permanent Threshold Shift—When 

PTS occurs, there is physical damage to 

the sound receptors in the ear. In severe 

cases, there can be total or partial 

deafness, whereas 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 (e.g., 

Richardson et al., 1995, p. 372ff; 

Gedamke et al., 2008). Single or 

occasional occurrences of mild TTS are 

not indicative of permanent auditory 

damage, but repeated or (in some cases) 

single exposures to a level well above 

that causing TTS onset might elicit PTS. 

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 

dBs above that inducing mild TTS if the 

animal were exposed to strong sound 

pulses with rapid rise time—see 

Appendix B(6) of USGS’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 six dB 

(Southall et al., 2007). 

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. 

Stranding 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 waters for 

commercial seismic surveys or (with 

rare exceptions) for seismic research; 

they 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 strandings of beaked whales with 

naval exercises involving mid-frequency 

active sonar 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 (6) of USGS’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 acousticallymediated bubble formation and growth 

or acoustic resonance of tissues. Some 

of these mechanisms are unlikely to 

apply in the case of impulse sounds. 

However, there are indications that gasbubble 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 one kHz. 

Typical military mid-frequency sonar 

emits non-impulse sounds at 

frequencies of two to 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; Ferna ́ndez 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 

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 (8,490 in3) array 

in the general area. The link between 

the stranding and the seismic surveys 

was inconclusive and not based on any 

physical evidence (Hogarth, 2002; 

Yoder, 2002). Nonetheless, the Gulf of 

California incident plus the beaked 

whale strandings near naval exercises 

involving use of mid-frequency sonar 

suggests a need for caution in 

conducting seismic surveys in areas 

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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, and 

(2) Differences between the sound 

sources operated by L–DEO and those 

involved in the naval exercises 

associated with strandings. 

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 

effects (Gentry, 2002) and direct noiseinduced bubble formations (Crum et al., 

2005) are implausible in the case of 

exposure to an impulsive broadband 

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 and some 

odontocetes, are especially unlikely to 

incur non-auditory physical effects. 

Potential Effects of Other Acoustic 

Devices 

MBES 

USGS will operate the Kongsberg EM 

122 MBES from the source vessel during 

the planned study. Sounds from the 

MBES are very short pulses, occurring 

for two to 15 ms once every five to 

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 (rms). The beam is 

narrow (1 to 2°) in fore-aft extent and 

wide (150°) in the cross-track extent. 

Each ping consists of eight (in water 

greater than 1,000 m deep) or four (in 

water less than 1,000 m deep) 

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 Kongsberg EM 122 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 to 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 Kongsberg EM 

122; and (2) are often directed close to 

horizontally versus more downward for 

the MBES. The area of possible 

influence of the MBES is much 

smaller—a narrow band below the 

source vessel. Also, the duration of 

exposure for a given marine mammal 

can be much longer for naval sonar. 

During USGS’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. Possible effects 

of an MBES on marine mammals are 

outlined below. 

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 sonars, 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 melas) (Rendell and 

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

During exposure to a 21 to 25 kHz 

‘‘whale-finding’’ sonar with a source 

level of 215 dB re 1 μPa, 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 and a 

beluga whale 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 USGS, 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 echosounder 

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 echosounder that 

included significant signal components 

down to 6 kHz. Results indicated that 

the two seals reacted to the 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 consequences 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 USGS is 

quite different than sonar used for Navy 

operations. Pulse duration of the MBES 

is very short relative to the naval sonar. 

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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 sonar often 

uses near-horizontally-directed sound. 

Those factors would all reduce the 

sound energy received from the MBES 

rather drastically relative to that from 

naval sonar. 

NMFS believes that the brief exposure 

of marine mammals to one pulse, or 

small numbers of signals, from the 

MBES is not likely to result in the 

harassment of marine mammals. 

SBP 

USGS will also operate an SBP from 

the source vessel during the proposed 

survey. Sounds from the SBP are very 

short pulses, occurring for one to four 

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. The SBP on the 

Langseth has a maximum source level of 

204 dB re 1 μPa. 

Kremser et al. (2005) noted that the 

probability of a cetacean swimming 

through the area of exposure when a 

bottom profiler emits a pulse is small— 

even for an SBP more powerful than 

that on the Langseth—if the animal was 

in the area, it would have to pass the 

transducer at close range in order to be 

subjected to sound levels that could 

cause TTS. 

Masking—Marine mammal 

communications will not be masked 

appreciably by the SBP signals given the 

directionality of the signal 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 are not expected 

unless marine mammals are 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. 

Acoustic Release Signals 

The acoustic release transponder used 

to communicate with the OBSs uses 

frequencies 9 to 13 kHz. These signals 

will be used very intermittently. It is 

unlikely that the acoustic release signals 

would have a significant effect on 

marine mammals through masking, 

disturbance, or hearing impairment. 

Any effects likely would be negligible 

given the brief exposure at presumably 

low levels. 

The potential effects to marine 

mammals described in this section of 

the document do not take into 

consideration the proposed monitoring 

and mitigation measures described later 

in this document (see the ‘‘Proposed 

Mitigation’’ and ‘‘Proposed Monitoring 

and Reporting’’ sections) which, as 

noted are designed to effect the least 

practicable adverse impact on affected 

marine mammal species and stocks. 

Anticipated Effects on Marine Mammal 

Habitat 

The proposed seismic survey will not 

result in any permanent impact on 

habitats used by the marine mammals in 

the proposed survey area, including the 

food sources they use (i.e., fish and 

invertebrates), and there will be no 

physical damage to any habitat. While it 

is anticipated that the specified activity 

may result in marine mammals avoiding 

certain areas due to temporary 

ensonification, this impact to habitat is 

temporary and reversible and was 

considered in further detail earlier in 

this document, as behavioral 

modification. The main impact 

associated with the proposed activity 

will be temporarily elevated noise levels 

and the associated direct effects on 

marine mammals, previously discussed 

in this notice. 

Anticipated Effects on Fish 

One reason for the adoption of airguns 

as the standard energy source for marine 

seismic surveys is that, unlike 

explosives, they have not been 

associated with large-scale fish kills. 

However, existing information on the 

impacts of seismic surveys on marine 

fish populations is limited (see 

Appendix D of USGS’s EA). There are 

three types of potential effects of 

exposure to seismic surveys: (1) 

Pathological, (2) physiological, and (3) 

behavioral. Pathological effects involve 

lethal and temporary or permanent sublethal injury. Physiological effects 

involve temporary and permanent 

primary and secondary stress responses, 

such as changes in levels of enzymes 

and proteins. Behavioral effects refer to 

temporary and (if they occur) permanent 

changes in exhibited behavior (e.g., 

startle and avoidance behavior). The 

three categories are interrelated in 

complex ways. For example, it is 

possible that certain physiological and 

behavioral changes could potentially 

lead to an ultimate pathological effect 

on individuals (i.e., mortality). 

The specific received sound levels at 

which permanent adverse effects to fish 

potentially could occur are little studied 

and largely unknown. Furthermore, the 

available information on the impacts of 

seismic surveys on marine fish is from 

studies of individuals or portions of a 

population; there have been no studies 

at the population scale. The studies of 

individual fish have often been on caged 

fish that were exposed to airgun pulses 

in situations not representative of an 

actual seismic survey. Thus, available 

information provides limited insight on 

possible real-world effects at the ocean 

or population scale. 

Hastings and Popper (2005), Popper 

(2009), and Popper and Hastings 

(2009a,b) provided recent critical 

reviews of the known effects of sound 

on fish. The following sections provide 

a general synopsis of the available 

information on the effects of exposure to 

seismic and other anthropogenic sound 

as relevant to fish. The information 

comprises results from scientific studies 

of varying degrees of rigor plus some 

anecdotal information. Some of the data 

sources may have serious shortcomings 

in methods, analysis, interpretation, and 

reproducibility that must be considered 

when interpreting their results (see 

Hastings and Popper, 2005). Potential 

adverse effects of the program’s sound 

sources on marine fish are noted. 

Pathological Effects—The potential 

for pathological damage to hearing 

structures in fish depends on the energy 

level of the received sound and the 

physiology and hearing capability of the 

species in question (see Appendix D 

USGS’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, 

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reproduction, etc.) are adversely 

affected. 

Little is known about the mechanisms 

and characteristics of damage to fish 

that may be inflicted by exposure to 

seismic survey sounds. Few data have 

been presented in the peer-reviewed 

scientific literature. As far as USGS and 

NMFS know, there are only two papers 

with proper experimental methods, 

controls, and careful pathological 

investigation implicating sounds 

produced by actual seismic survey 

airguns in causing adverse anatomical 

effects. One such study indicated 

anatomical damage, and the second 

indicated TTS in fish hearing. The 

anatomical case is McCauley et al. 

(2003), who found that exposure to 

airgun sound caused observable 

anatomical damage to the auditory 

maculae of pink snapper (Pagrus 

auratus). This damage in the ears had 

not been repaired in fish sacrificed and 

examined almost two months after 

exposure. On the other hand, Popper et 

al. (2005) documented only TTS (as 

determined by auditory brainstem 

response) in two of three fish species 

from the Mackenzie River Delta. This 

study found that broad whitefish 

(Coregonus nasus) exposed to five 

airgun shots were not significantly 

different from those of controls. During 

both studies, the repetitive exposure to 

sound was greater than would have 

occurred during a typical seismic 

survey. However, the substantial lowfrequency energy produced by the 

airguns [less than 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 nine 

m in the former case and less than two 

m in the latter). Water depth sets a 

lower limit on the lowest sound 

frequency that will propagate (the 

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

wavelength (Urick, 1983; Rogers and 

Cox, 1988). 

Wardle et al. (2001) suggested that in 

water, acute injury and death of 

organisms exposed to seismic energy 

depends primarily on two features of 

the sound source: (1) The received peak 

pressure and (2) the time required for 

the pressure to rise and decay. 

Generally, as received pressure 

increases, the period for the pressure to 

rise and decay decreases, and the 

chance of acute pathological effects 

increases. According to Buchanan et al. 

(2004), for the types of seismic airguns 

and arrays involved with the proposed 

program, the pathological (mortality) 

zone for fish 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; Thomsen, 2002; Hassel et 

al., 2003; Popper et al., 2005; Boeger et 

al., 2006). 

Some studies have reported, some 

equivocally, that mortality of fish, fish 

eggs, or larvae can occur close to 

seismic sources (Kostyuchenko, 1973; 

Dalen and Knutsen, 1986; Booman 

et al., 1996; Dalen et al., 1996). Some of 

the reports claimed seismic effects from 

treatments quite different from actual 

seismic survey sounds or even 

reasonable surrogates. However, Payne 

et al. (2009) reported no statistical 

differences in mortality/morbidity 

between control and exposed groups of 

capelin eggs or monkfish larvae. Saetre 

and Ona (1996) applied a ‘worst-case 

scenario’ mathematical model to 

investigate the effects of seismic energy 

on fish eggs and larvae. They concluded 

that mortality rates caused by exposure 

to seismic surveys are so low, as 

compared to natural mortality rates, that 

the impact of seismic surveying on 

recruitment to a fish stock must be 

regarded as insignificant. 

Physiological Effects—Physiological 

effects refer to cellular and/or 

biochemical responses of fish to 

acoustic stress. Such stress potentially 

could affect fish populations by 

increasing mortality or reducing 

reproductive success. Primary and 

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; 

Santulli et al., 1999; McCauley et al., 

2000 a,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 USGS’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 (e.g., 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 

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. 

Anticipated Effects on Invertebrates 

The existing body of information on 

the impacts of seismic survey sound on 

marine invertebrates is very limited. 

However, there is some unpublished 

and very limited evidence of the 

potential for adverse effects on 

invertebrates, thereby justifying further 

discussion and analysis of this issue. 

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 USGS’s 

EA). 

The only information available on the 

impacts of seismic surveys on marine 

invertebrates involves studies of 

individuals; there have been no studies 

at the population scale. Thus, available 

information provides limited insight on 

possible real-world effects at the 

regional or ocean scale. The most 

important aspect of potential impacts 

concerns how exposure to seismic 

survey sound ultimately affects 

invertebrate populations and their 

viability, including availability to 

fisheries. 

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Literature reviews of the effects of 

seismic and other underwater sound on 

invertebrates were provided by 

Moriyasu et al. (2004) and Payne et al. 

(2008). The following sections provide a 

synopsis of available information on the 

effects of exposure to seismic survey 

sound on species of decapod 

crustaceans and cephalopods, the two 

taxonomic groups of invertebrates on 

which most such studies have been 

conducted. The available information is 

from studies with variable degrees of 

scientific soundness and from anecdotal 

information. A more detailed review of 

the literature on the effects of seismic 

survey sound on invertebrates is 

provided in Appendix E of USGS’s EA. 

Pathological Effects—In water, lethal 

and sub-lethal injury to organisms 

exposed to seismic survey sound 

appears to depend on at least two 

features of the sound source: (1) The 

received peak pressure; and (2) the time 

required for the pressure to rise and 

decay. Generally, as received pressure 

increases, the period for the pressure to 

rise and decay decreases, and the 

chance of acute pathological effects 

increases. For the 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, at most; 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., 

2000 a,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 the article 

provides little evidence to support this 

claim. 

Physiological Effects—Physiological 

effects refer mainly to biochemical 

responses by marine invertebrates to 

acoustic stress. Such stress potentially 

could affect invertebrate populations by 

increasing mortality or reducing 

reproductive success. Primary and 

secondary stress responses (i.e., changes 

in haemolymph levels of enzymes, 

proteins, etc.) of crustaceans have been 

noted several days or months after 

exposure to seismic survey sounds 

(Payne et al., 2007). The periods 

necessary for these biochemical changes 

to return to normal are variable and 

depend on numerous aspects of the 

biology of the species and of the sound 

stimulus. 

Behavioral Effects—There is 

increasing interest in assessing the 

possible direct and indirect effects of 

seismic and other sounds on 

invertebrate behavior, particularly in 

relation to the consequences for 

fisheries. Changes in behavior could 

potentially affect such aspects as 

reproductive success, distribution, 

susceptibility to predation, and 

catchability by fisheries. Studies 

investigating the possible behavioral 

effects of exposure to seismic survey 

sound on crustaceans and cephalopods 

have been conducted on both uncaged 

and caged animals. In some cases, 

invertebrates exhibited startle responses 

(e.g., squid in McCauley et al., 2000 a,b). 

In other cases, no behavioral impacts 

were noted (e.g., crustaceans in 

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

There have been anecdotal reports of 

reduced catch rates of shrimp shortly 

after exposure to seismic surveys; 

however, other studies have not 

observed any significant changes in 

shrimp catch rate (Andriguetto-Filho et 

al., 2005). Similarly, Parry and Gason 

(2006) did not find any evidence that 

lobster catch rates were affected by 

seismic surveys. Any adverse effects on 

crustacean and cephalopod behavior or 

fisheries attributable to seismic survey 

sound depend on the species in 

question and the nature of the fishery 

(season, duration, fishing method). 

Proposed Mitigation 

In order to issue an Incidental Take 

Authorization (ITA) under Section 

101(a)(5)(D) of the MMPA, NMFS must 

set forth the permissible methods of 

taking pursuant to such activity, and 

other means of effecting the least 

practicable adverse impact on such 

species or stock and its habitat, paying 

particular attention to rookeries, mating 

grounds, and areas of similar 

significance, and the availability of such 

species or stock for taking for certain 

subsistence uses. 

USGS has based the mitigation 

measures described herein, to be 

implemented for the proposed seismic 

survey, on the following: 

(1) Protocols used during previous 

USGS and L–DEO seismic research 

cruises as approved by NMFS; 

(2) Previous IHA applications and 

IHAs approved and authorized by 

NMFS; and 

(3) Recommended best practices in 

Richardson et al. (1995), Pierson et al. 

(1998), and Weir and Dolman, (2007). 

To reduce the potential for 

disturbance from acoustic stimuli 

associated with the activities, USGS 

and/or its designees has proposed to 

implement the following mitigation 

measures for marine mammals: 

(1) Proposed exclusion zones; 

(2) Power-down procedures; 

(3) Shut-down procedures; 

(4) Ramp-up procedures; and 

(5) Special procedures for situations 

and species of concern. 

Planning Phase—In designing the 

proposed seismic survey, USGS has 

considered potential environmental 

impacts including seasonal, biological, 

and weather factors; ship schedules; and 

equipment availability. Part of the 

considerations was whether the research 

objectives could be met with a smaller 

source; tests will be conducted to 

determine whether the two-string subarray (3,300 in3) will be satisfactory to 

accomplish the geophysical objectives. 

If so, the smaller array will be used to 

minimize environmental impact. Also, 

the array will be powered-down to a 

single airgun during turns, and the array 

will be shut-down during OBS 

deployment and retrieval. 

Proposed Exclusion Zones—Received 

sound levels have been determined by 

empirical corrected measurements for 

the 36 airgun array, and an L–DEO 

model was used to predict the EZs for 

the single 1,900LL 40 in3 airgun, which 

will be used during power-downs. 

Results were recently reported for 

propagation measurements of pulses 

from the 36 airgun array in two water 

depths (approximately 1,600 m and 50 

m [5,249 to 164 ft]) in the Gulf of 

Mexico in 2007 to 2008 (Tolstoy et al., 

2009). It would be prudent to use the 

empirical values that resulted to 

determine EZs for the airgun array. 

Results of the propagation 

measurements (Tolstoy et al., 2009) 

showed that radii around the airguns for 

various received levels varied with 

water depth. During the proposed study, 

all survey effort will take place in deep 

(greater than 1,000 m) water, so 

propagation in shallow water is not 

relevant here. The depth of the array 

was different in the Gulf of Mexico 

calibration study (6 m [19.7 ft]) than in 

the proposed survey (9 m); thus, 

correction factors have been applied to 

the distances reported by Tolstoy et al. 

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(2009). The correction factors used were 

the ratios of the 160, 180, and 190 dB 

distances from the modeled results for 

the 6,600 in3 airgun array towed at 6 m 

versus 9 m. Based on the propagation 

measurements and modeling, the 

distances from the source where sound 

levels are predicted to be 190, 180, and 

160 dB re 1 μPa (rms) were determined 

(see Table 1 above). The 180 and 190 dB 

radii are to 940 m and 400 m, 

respectively, as specified by NMFS 

(2000); these levels were used to 

establish the EZs. If the PSVO detects 

marine mammal(s) within or about to 

enter the appropriate EZ, the airguns 

will be powered-down (or shut-down, if 

necessary) immediately. 

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 are 

no longer in or about to enter the EZ. A 

power-down of the airgun array can also 

occur when the vessel is moving from 

one seismic line to another. During a 

power-down for mitigation, USGS will 

operate one airgun. The continued 

operation of one airgun is intended to 

alert marine mammals to the presence of 

the seismic vessel in the area. In 

contrast, a shut-down occurs when the 

Langseth suspends all airgun activity. 

If the PSVO detects a marine mammal 

outside the EZ, but it is likely to enter 

the EZ, USGS will power-down the 

airguns before the animal is within the 

EZ. Likewise, if a mammal is already 

within the EZ, when first detected 

USGS will power-down the airguns 

immediately. During a power-down of 

the airgun array, USGS will also operate 

the 40 in3 airgun. If a marine mammal 

is detected within or near the smaller 

EZ around that single airgun (Table 1), 

USGS will shut-down the airgun (see 

next section). 

Following a power-down, USGS will 

not resume airgun activity until the 

marine mammal has cleared the EZ. L– 

DEO will consider the animal to have 

cleared the EZ if: 

• A PSVO has visually observed the 

animal leave the EZ, or 

• A PSVO has not sighted the animal 

within the EZ for 15 min for species 

with shorter dive durations (i.e., small 

odontocetes or pinnipeds), or 30 min for 

species with longer dive durations (i.e., 

mysticetes and large odontocetes, 

including sperm, pygmy sperm, dwarf 

sperm, killer, and beaked whales). 

During airgun operations following a 

power-down (or shut-down) whose 

duration has exceeded the time limits 

specified previously, USGS will rampup the airgun array gradually (see Shutdown and Ramp-up Procedures). 

Shut-down Procedures—USGS will 

shut down the operating airgun(s) if a 

marine mammal is seen within or 

approaching the EZ for the single 

airgun. USGS will implement a shutdown: 

(1) If an animal enters the EZ of the 

single airgun after USGS has initiated a 

power-down; or 

(2) If an animal is initially seen within 

the EZ of the single airgun when more 

than one airgun (typically the full 

airgun array) is operating. 

USGS will not resume airgun activity 

until the marine mammal has cleared 

the EZ, or until the PSVO 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 section. 

Ramp-up Procedures—USGS will 

follow a ramp-up procedure when the 

airgun array begins operating after a 

specified period without airgun 

operations or when a power-down has 

exceeded that period. USGS proposes 

that, for the present cruise, this period 

would be approximately eight min. This 

period is based on the 180 dB radius 

(940 m) for the 36 airgun array towed at 

a depth of 9 m in relation to the 

minimum planned speed of the 

Langseth while shooting (7.4 km/hr). 

USGS and L–DEO have used similar 

periods (approximately 8 to 10 min) 

during previous L–DEO surveys. 

Ramp-up will begin with the smallest 

airgun 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 six dB per five min 

period over a total duration of 

approximately 35 min. During ramp-up, 

the PSOs will monitor the EZ, and if 

marine mammals are sighted, USGS will 

implement a power-down or shut-down 

as though the full airgun 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, USGS will not commence the 

ramp-up 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 safety 

zone for that array will not be visible 

during those conditions. If one airgun 

has operated during a power-down 

period, ramp-up to full power will be 

permissible at night or in poor visibility, 

on the assumption that marine 

mammals will be alerted to the 

approaching seismic vessel by the 

sounds from the single airgun and could 

move away. USGS will not initiate a 

ramp-up of the airguns if a marine 

mammal is sighted within or near the 

applicable EZs during the day or close 

to the vessel at night. 

Special Procedures for Situations and 

Species of Concern—USGS will 

implement special mitigation 

procedures as follows: 

• The airguns will be shut-down 

immediately if ESA-listed species for 

which no takes are being requested (i.e., 

North Pacific right, sei, blue, and beluga 

whales) are sighted at any distance from 

the vessel. Ramp-up will only begin if 

the whale has not been seen for 30 min. 

• Concentrations of humpback, fin, 

and/or killer whales will be avoided if 

possible, and the array will be powereddown if necessary. For purposes of this 

proposed survey, a concentration or 

group of whales will consist of three or 

more individuals visually sighted and 

do not appear to be traveling (e.g., 

feeding, socializing, etc.). 

NMFS has carefully evaluated the 

applicant’s proposed mitigation 

measures and has considered a range of 

other measures in the context of 

ensuring that NMFS prescribes the 

means of effecting the least practicable 

adverse impact on the affected marine 

mammal species and stocks and their 

habitat. NMFS’s evaluation of potential 

measures included consideration of the 

following factors in relation to one 

another: 

(1) The manner in which, and the 

degree to which, the successful 

implementation of the measure is 

expected to minimize adverse impacts 

to marine mammals; 

(2) The proven or likely efficacy of the 

specific measure to minimize adverse 

impacts as planned; and 

(3) The practicability of the measure 

for applicant implementation. 

Based on NMFS’s evaluation of the 

applicant’s proposed measures, as well 

as other measures considered by NMFS 

or recommended by the public, NMFS 

has preliminarily determined that the 

proposed mitigation measures provide 

the means of effecting the least 

practicable adverse impacts on marine 

mammal species or stocks and their 

habitat, paying particular attention to 

rookeries, mating grounds, and areas of 

similar significance. 

Proposed Monitoring and Reporting 

In order to issue an ITA for an 

activity, section 101(a)(5)(D) of the 

MMPA states that NMFS must set forth 

‘‘requirements pertaining to the 

monitoring and reporting of such 

taking.’’ The MMPA implementing 

regulations at 50 CFR 216.104 (a)(13) 

indicate that requests for IHAs must 

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include the suggested means of 

accomplishing the necessary monitoring 

and reporting that will result in 

increased knowledge of the species and 

of the level of taking or impacts on 

populations of marine mammals that are 

expected to be present in the action 

area. 

Monitoring 

USGS proposes to sponsor marine 

mammal monitoring during the 

proposed project, in order to implement 

the proposed mitigation measures that 

require real-time monitoring, and to 

satisfy the anticipated monitoring 

requirements of the IHA. USGS’s 

proposed Monitoring Plan is described 

below this section. USGS 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. USGS 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 

PSVOs will be based aboard the 

seismic source vessel and will watch for 

marine mammals near the vessel during 

daytime airgun operations and during 

any ramp-ups at night. PSVOs will also 

watch for marine mammals near the 

seismic vessel for at least 30 min prior 

to the start of airgun operations after an 

extended shut-down. PSVOs will 

conduct observations during daytime 

periods when the seismic system is not 

operating for comparison of sighting 

rates and behavior with and without 

airgun operations and between 

acquisition periods. Based on PSVO 

observations, the airguns will be 

powered-down or shut-down when 

marine mammals are observed within or 

about to enter a designated 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 

central GOA, at least four PSOs will be 

based aboard the Langseth. USGS will 

appoint the PSOs with NMFS’ 

concurrence. Observations will take 

place during ongoing daytime 

operations and nighttime ramp-ups of 

the airguns. During the majority of 

seismic operations, two PSVOs will be 

on duty from the observation tower to 

monitor marine mammals near the 

seismic vessel. Use of two simultaneous 

PSVOs will increase the effectiveness of 

detecting animals near the source 

vessel. However, during meal times and 

bathroom breaks, it is sometimes 

difficult to have two PSVOs on effort, 

but at least one PSVO will be on duty. 

PSVO(s) will be on duty in shifts of 

duration no longer than 4 hr. 

Two PSVOs will also be on visual 

watch during all nighttime ramp-ups of 

the seismic airguns. A third PSO will 

monitor the PAM equipment 24 hours a 

day to detect vocalizing marine 

mammals present in the action area. In 

summary, a typical daytime cruise 

would have scheduled two PSVOs on 

duty from the observation tower, and a 

third PSO on PAM. Other crew will also 

be instructed to assist in detecting 

marine mammals and implementing 

mitigation requirements (if practical). 

Before the start of the seismic survey, 

the crew will be given additional 

instruction on how to do so. 

The Langseth is a suitable platform for 

marine mammal observations. When 

stationed on the observation platform, 

the eye level will be approximately 

21.5 m (70.5 ft) above sea level, and the 

PSVO will have a good view around the 

entire vessel. During daytime, the 

PSVOs 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 

binocular-image intensifier or 

equivalent), when required. Laser rangefinding binoculars (Leica LRF 1200 laser 

rangefinder or equivalent) will be 

available to assist with distance 

estimation. Those are useful in training 

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. 

When marine mammals are detected 

within or about to enter the designated 

EZ, the airguns will immediately be 

powered-down or shut-down if 

necessary. The PSO(s) will continue to 

maintain watch to determine when the 

animal(s) are outside the EZ by visual 

confirmation. Airgun operations will 

not resume until the animal is 

confirmed to have left the EZ, or if not 

observed after 15 min for species with 

shorter dive durations (small 

odontocetes and pinnipeds) or 30 min 

for species with longer dive durations 

(mysticetes and large odontocetes, 

including sperm, killer, and beaked 

whales). 

Passive Acoustic Monitoring (PAM) 

PAM will complement the visual 

monitoring program, when practicable. 

Visual monitoring typically is not 

effective during periods of poor 

visibility or at night, and even with 

good visibility, is unable to detect 

marine mammals when they are below 

the surface or beyond visual range. 

Besides the three PSVOs, an 

additional Protected Species Acoustic 

Observer (PSAO) with primary 

responsibility for PAM will also be 

aboard the vessel. USGS can use 

acoustic monitoring in addition to 

visual observations to improve 

detection, identification, and 

localization 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 PSVOs can be advised when 

cetaceans are detected. When bearings 

(primary and mirror-image) to calling 

cetacean(s) are determined, the bearings 

will be relayed to the visual observer to 

help him/her sight the calling animal(s). 

The PAM system consists of hardware 

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

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

towed hydrophone array that is 

connected to the vessel by a 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 laboratory where the acoustic 

station and signal conditioning and 

processing system will be located. The 

digitized signal and PAM system is 

monitored by PSOs at a station in the 

main laboratory. The lead in from the 

hydrophone array is approximately 400 

m (1,312 ft) long, the active section of 

the array is approximately 56 m (184 ft) 

long, and the hydrophone array is 

typically towed at depths of less than 20 

m (66 ft). 

Ideally, the PSAO will monitor the 

towed hydrophones 24 hr per day at the 

seismic survey area during airgun 

operations, and during most periods 

when the Langseth is underway while 

the airguns are not operating. However, 

PAM may not be possible if damage 

occurs to both the primary and back-up 

hydrophone arrays during operations. 

The primary PAM streamer on the 

Langseth is a digital hydrophone 

streamer. Should the digital streamer 

fail, back-up systems should include an 

analog spare streamer and a hullmounted hydrophone. Every effort 

would be made to have a working PAM 

system during the cruise. In the unlikely 

event that all three of these systems 

were to fail, USGS would continue 

science acquisition with the visualbased observer program. The PAM 

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system is a supplementary enhancement 

to the visual monitoring program. If 

weather conditions were to prevent the 

use of PAM then conditions would also 

likely prevent the use of the airgun 

array. 

One PSAO 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. PSAOs 

monitoring the acoustical data will be 

on shift for one to six hours at a time. 

Besides the PSVO, an additional PSAO 

with primary responsibility for PAM 

will also be aboard the source vessel. 

All PSVOs 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 

PSAO will contact the PSVO 

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. Data entry will 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. 

PSVO Data and Documentation 

PSVOs will record data to estimate 

the numbers of marine mammals 

exposed to various received sound 

levels and to document apparent 

disturbance reactions or lack thereof. 

Data will be used to estimate numbers 

of animals potentially ‘taken’ by 

harassment (as defined in the MMPA). 

They will also provide information 

needed to order a power-down or shutdown of the airguns when a marine 

mammal is within or near the EZ. 

Observations will also be made during 

daytime periods when the Langseth is 

underway without seismic operations. 

In addition to transits to, from, and 

through the study area, there will also 

be opportunities to collect baseline 

biological data during the deployment 

and recovery of OBSs. 

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 an electronic database. The 

accuracy of the data entry will be 

verified by computerized data validity 

checks as the data are entered and by 

subsequent manual checking of the 

database. These procedures will allow 

initial summaries of data to be prepared 

during and shortly after the field 

program, and will facilitate transfer of 

the data to statistical, graphical, and 

other programs for further processing 

and archiving. 

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. 

3. Data on the occurrence, 

distribution, and activities of marine 

mammals in the area where the seismic 

study is conducted. 

4. Information to compare the 

distance and distribution of marine 

mammals relative to the source vessel at 

times with and without seismic activity. 

5. Data on the behavior and 

movement patterns of marine mammals 

seen at times with and without seismic 

activity. 

USGS will submit a report to NMFS 

and NSF within 90 days after the end of 

the cruise. The report will describe the 

operations that were conducted and 

sightings of marine mammals near the 

operations. The report will 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 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. 

USGS will report all injured or dead 

marine mammals (regardless of cause) to 

NMFS as soon as practicable. The report 

should include the species or 

description of the animal, the condition 

of the animal, location, time first found, 

observed behaviors (if alive) and photo 

or video, if available. In the 

unanticipated event that any taking of a 

marine mammal in a manner prohibited 

by the proposed IHA occurs, such as an 

injury, serious injury, or mortality, and 

are judged to result from the proposed 

activities, the operator will immediately 

report the incident to the Chief of the 

Permits, Conservation, and Education 

Division, Office of Protected Resources, 

NMFS. The operator will postpone the 

proposed activities until NMFS is able 

to review the circumstances of the take. 

NMFS will work with the operator to 

determine whether modifications in the 

activities are appropriate and necessary, 

and notify the operator that they may 

resume sound source operations. 

Estimated Take by Incidental 

Harassment 

Except with respect to certain 

activities not pertinent here, the MMPA 

defines ‘‘harassment’’ as: 

any act of pursuit, torment, or annoyance 

which (i) has the potential to injure a marine 

mammal or marine mammal stock in the wild 

[Level A harassment]; or (ii) has the potential 

to disturb a marine mammal or marine 

mammal stock in the wild by causing 

disruption of behavioral patterns, including, 

but not limited to, migration, breathing, 

nursing, breeding, feeding, or sheltering 

[Level B harassment]. 

Only take by Level B harassment is 

anticipated and authorized as a result of 

the proposed marine geophysical survey 

in the central GOA. Acoustic stimuli 

(i.e., increased underwater sound) 

generated during the operation of the 

seismic airgun array may have the 

potential to cause marine mammals in 

the survey area to be exposed to sounds 

at or greater than 160 dB or cause 

temporary, short-term changes in 

behavior. There is no evidence that the 

planned activities could result in injury, 

serious injury, or mortality within the 

specified geographic area for which 

USGS seeks the IHA. The required 

mitigation and monitoring measures 

will minimize any potential risk for 

injury, serious injury, or mortality. 

The following sections describe 

USGS’s methods to estimate take by 

incidental harassment and present the 

applicant’s estimates of the numbers of 

marine mammals that could be affected 

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during the proposed seismic program. 

The estimates are based on a 

consideration of the number of marine 

mammals that could be disturbed 

appreciably by operations with the 36 

airgun array to be used during 

approximately 3,300 km (1,782 nmi) of 

survey lines in the central GOA. 

USGS assumes that, during 

simultaneous operations of the airgun 

array and the other sources, any marine 

mammals close enough to be affected by 

the MBES and 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 

previously. Such reactions are not 

considered to constitute ‘‘taking’’ 

(NMFS, 2001). Therefore, USGS 

provides no additional allowance for 

animals that could be affected by sound 

sources other than airguns. 

There are several sources of 

systematic data on the numbers and 

distributions of marine mammals in the 

coastal and nearshore areas of the GOA, 

but there are fewer data for offshore 

areas. Vessel-based surveys in the 

northern and western GOA from the 

Kenai Peninsula to the central Aleutian 

Islands during July to August, 2001 to 

2001 (Zerbini et al., 2003, 2006, 2007) 

and in the northern and western GOA 

from Prince William Sound to 

approximately 160° West off the Alaska 

Peninsula during June 26 to July 15, 

2003 (Waite, 2003) were confined to 

waters less than 1,000 m deep, and most 

effort was in depths less than 100 m. 

Similarly, Dahlheim et al. (2000) 

conducted aerial surveys of the 

nearshore waters from Bristol Bay to 

Dixon Entrance for harbor porpoises 

during 1993, and Dahlheim and Towell 

(1994) conducted vessel-based surveys 

of Pacific white-sided dolphins in the 

inland waterways of southeast Alaska 

during April to May, June or July, and 

September to early October of 1991 to 

1993. 

Deeper water was included in several 

surveys. In a report on a seismic cruise 

in southeast Alaska from Dixon 

Entrance to Kodiak Island during 

August to September, 2004, MacLean 

and Koski (2005) included density 

estimates of cetaceans and pinnipeds for 

each of three depth ranges (less than 100 

m, 100 to 1,000 m, and greater than 

1,000 m) during non-seismic periods. 

Hauser and Holst (2009) reported 

density estimates during non-seismic 

periods for all marine mammals sighted 

during a September to early October 

seismic cruise in southeast Alaska for 

each of the same three depth ranges as 

MacLean and Koski (2005). Rone et al. 

(2010) conducted surveys of nearshore 

and offshore strata in the GOA during 

April, 2009, with much of their survey 

effort in water depths greater than 1,000 

m. The Department of the Navy (DON) 

(2009) estimated densities of several 

species of marine mammals in the 

offshore GOA based on surveys by other 

researchers. 

Table 2 (Table 3 of the IHA 

application) gives the estimated average 

(best) and maximum densities of marine 

mammals expected to occur in the deep, 

offshore waters of the proposed survey 

area. USGS used the densities reported 

by MacLean and Koski (2005) and 

Hauser and Holst (2009) for greater than 

1,000 m, which were corrected for both 

detectability and availability biases. 

USGS calculated density estimates from 

effort and sightings in water depths 

greater than 1,000 m in Rone et al. 

(2010) for humpback, fin, and killer 

whales and Dall’s porpoise, and in 500 

to 1,000 m depths of Waite (2003) for 

Cuvier’s and Baird’s beaked whales, 

using values for ƒ(0) and g(0) from 

Barlow and Forney (2007). Finally, 

USGS used seasonal densities for 

pinnipeds from DON (2009), which 

were based on counts at haul-out sites 

and biological (mostly breeding) 

information to estimate in-water 

densities. 

There is some uncertainty about the 

representativeness of the data and the 

assumptions used in the calculations 

below for two main reasons: (1) The 

surveys from which densities were 

derived were at different times of year: 

April (Rone et al., 2010), June to July 

(Waite, 2003), August to September 

(MacLean and Koski, 2005), and 

September to October (Hauser and 

Holst, 2009); and (2) the MacLean and 

Koski (2005) and Hauser and Holst 

(2009) surveys were conducted 

primarily in southeast Alaska (east of 

the proposed study area). However, the 

approach used here is believed to be the 

best available approach. 

Also, to provide some allowance for 

these uncertainties, ‘‘maximum 

estimates’’ as well as ‘‘best estimates’’ of 

the densities present and numbers 

potentially affected have been derived. 

Best estimates of cetacean density are 

effort-weighted mean densities from the 

various surveys, whereas maximum 

estimates of density come from the 

individual survey that provided the 

highest density. For marine mammals 

where only one density estimate was 

available, the maximum is 1.5× the best 

estimate. 

For one species, the Dall’s porpoise, 

density estimates in the original reports 

are much higher than densities expected 

during the proposed survey, because 

this porpoise is attracted to vessels. 

USGS estimates for Dall’s porpoises are 

from vessel-based surveys without 

seismic activity; they are overestimates 

possibly by a factor of 5x, given the 

tendency of this species to approach 

vessels (Turnock and Quinn, 1991). 

Noise from the airgun array during the 

proposed survey is expected to at least 

reduce and possibly eliminate the 

tendency of this porpoise to approach 

the vessel. Dall’s porpoises are tolerant 

of small airgun sources (MacLean and 

Koski, 2005) and tolerated higher sound 

levels than other species during a largearray survey (Bain and Williams, 2006); 

however, they did respond to that and 

another large airgun array by moving 

away (Calambokidis and Osmek, 1998; 

Bain and Williams, 2006). Because of 

the probable overestimates, the best and 

maximum estimates for Dall’s porpoises 

shown in Table 2 (Table 3 of the IHA 

application) are one-quarter of the 

reported densities. In fact, actual 

densities are probably slightly lower 

than that. 

USGS’s estimates of exposures to 

various sound levels assume that the 

proposed surveys will be fully 

completed including the contingency 

line; in fact, the ensonified areas 

calculated using the planned number of 

line-km have been increased by 25% to 

accommodate lines that may need to be 

repeated, equipment testing, etc. As is 

typical during offshore ship surveys, 

inclement weather and equipment 

malfunctions are likely to cause delays 

and may limit the number of useful linekilometers of seismic operations that 

can be undertaken. Furthermore, any 

marine mammal sightings within or 

near the designated EZs will result in 

the power-down or shut-down of 

seismic operations as a mitigation 

measure. Thus, the following estimates 

of the numbers of marine mammals 

potentially exposed to sound levels of 

160 dB re 1 μPa (rms) are precautionary 

and probably overestimate the actual 

numbers of marine mammals that might 

be involved. These estimates also 

assume that there will be no weather, 

equipment, or mitigation delays, which 

is highly unlikely. 

USGS estimated the number of 

different individuals that may be 

exposed to airgun sounds with received 

levels greater than or equal to 160 dB re 

1 μPa (rms) on one or more occasions by 

considering the total marine area that 

would be within the 160 dB radius 

around the operating airgun array on at 

least one occasion and the expected 

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18186 Federal Register / Vol. 76, No. 63 / Friday, April 1, 2011 / Notices 

density of marine mammals. The 

number of possible exposures 

(including repeated exposures of the 

same individuals) can be estimated by 

considering the total marine area that 

would be within the 160 dB radius 

around the operating airguns, including 

areas of overlap. In the proposed survey, 

the seismic lines are widely spaced in 

the survey area, so few individual 

marine mammals would be exposed 

more than once during the survey. The 

area including overlap is only 1.13 

times the area excluding overlap. 

Moreover, it is unlikely that a particular 

animal would stay in the area during the 

entire survey. The number of different 

individuals potentially exposed to 

received levels greater than or equal to 

160 re 1 μPa was calculated by 

multiplying: 

(1) The expected species density, 

either ‘‘mean’’ (i.e., best estimate) or 

‘‘maximum’’, times 

(2) the anticipated area to be 

ensonified to that level during airgun 

operations excluding overlap. 

The area expected to be ensonified 

was determined by entering the planned 

survey lines into a MapInfo GIS, using 

the GIS to identify the relevant areas by 

‘‘drawing’’ the applicable 160 dB buffer 

(see Table 1 of the IHA application) 

around each seismic line, and then 

calculating the total area within the 

buffers. Areas of overlap (because of 

lines being closer together than the 160 

dB radius) were limited and included 

only once when estimating the number 

of individuals exposed. Before 

calculating numbers of individuals 

exposed, the areas were increased by 

25% as a precautionary measure. 

Table 2 (Table 4 of the IHA 

application) shows the best and 

maximum estimates of the number of 

different individual marine mammals 

that potentially could be exposed to 

greater than or equal to 160 dB re 1 μPa 

(rms) during the seismic survey if no 

animals moved away from the survey 

vessel. The requested take 

authorization, given in Table 3 (the far 

right column of Table 4 of the IHA 

application), is based on the maximum 

estimates rather than the best estimates 

of the numbers of individuals exposed, 

because of uncertainties about the 

representativeness of the density data 

discussed previously. 

Applying the approach described 

above, approximately 20,933 km2

(6,103.1 nmi2) (approximately 26,166 

km2 [7,628.8 nmi2] including the 25% 

contingency) would be within the 160 

dB isopleths on one or more occasions 

during the survey, assuming that the 

contingency line is completed. Because 

this approach does not allow for 

turnover in the marine mammal 

populations in the study area during the 

course of the survey, the actual number 

of individuals exposed could be 

underestimated. However, the approach 

assumes that no cetaceans will move 

away from or toward the trackline as the 

Langseth approaches in response to 

increasing sound levels prior to the time 

the levels reach 160 dB, which will 

result in overestimates for those species 

known to avoid seismic vessels. 

The ‘‘best estimate’’ of the number of 

individual cetaceans that could be 

exposed to seismic sounds with greater 

than or equal to 160 dB re 1 μPa (rms) 

during the proposed survey is 776 (see 

Table 4 of the IHA application). That 

total includes 56 humpback, 63 fin, 8 

sperm, 34 Cuvier’s beaked, 11 Baird’s 

beaked, and 82 killer whales, which 

would represent 0.3%, 0.4%, less than 

0.1%, 0.2%, 0.2%, and 1% of the 

regional populations, respectively. 

Dall’s porpoises are expected to be the 

most common species in the study area; 

the best estimate of the number of Dall’s 

porpoises that could be exposed is 522 

or less than 0.1% of the regional 

population. This may be a slight 

overestimate because the estimated 

densities are slight overestimates. 

Estimates for other species are lower. 

The ‘‘maximum estimates’’ total 1,882 

cetaceans. ‘‘Best estimates’’ of 256 Steller 

sea lions and 2,771 northern fur seals 

could be exposed to airgun sounds with 

received levels greater than or equal to 

160 dB re 1 μPa (rms). These estimates 

represent 0.6% of the Steller sea lion 

regional population and less than 0.1% 

of the northern fur seal regional 

population. The estimated numbers of 

pinnipeds that could be exposed to 

received levels greater than or equal to 

160 dB re 1 μPa (rms) are probably 

overestimates of the actual numbers that 

will be affected. During the June survey 

period, the Steller sea lion is in its 

breeding season, with males staying on 

land and females with pups generally 

staying close to the rookeries in shallow 

water. Male northern fur seals are at 

their rookeries in June, and adult 

females are either there or migrating 

there, possibly through the survey area. 

No take has been requested for North 

Pacific right, minke, sei, and blue 

whales, Stejneger’s beaked whales, 

beluga whales, Pacific white-sided and 

Risso’s dolphins, short-finned pilot 

whales, harbor porpoises, Northern 

elephant and harbor seals, and 

California sea lions. 

TABLE 3—ESTIMATES OF THE POSSIBLE NUMBERS OF MARINE MAMMALS EXPOSED TO DIFFERENT SOUND LEVELS ≥160 

DB DURING USGS’S PROPOSED SEISMIC SURVEY IN THE CENTRAL GOA DURING JUNE 2011. 

Species 

Estimated number 

of individuals 

exposed to sound 

levels 

≥160 dB re 1 μPa 

(Best 1) 

Estimated number 

of individuals exposed to sound 

levels 

≥160 dB re 1 μPa 

(Maximum 1) 

Requested take 

authorization 

Approximate 

percent of 

regional 

population 2

(Best) 

Balaenopteridae: 

North Pacific right whale .................................................. 0 0 0 0 

Gray whale ....................................................................... NA NA NA NA 

Humpback whale .............................................................. 56 171 171 0.3 

Minke whale ...................................................................... 0 0 0 0 

Sei whale .......................................................................... 0 0 0 0 

Fin whale .......................................................................... 63 155 155 0.4 

Blue whale ........................................................................ 0 0 0 0 

Physeteridae: 

Sperm whale ..................................................................... 8 35 35 <0.1 

Ziphidae: 

Cuvier’s beaked whale ..................................................... 34 38 38 0.2 

Baird’s beaked whale ....................................................... 11 13 13 0.2 

Stejneger’s beaked whale ................................................ 0 0 0 0 

Delphinidae: 

Beluga whale .................................................................... NA NA NA NA 

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Federal Register / Vol. 76, No. 63 / Friday, April 1, 2011 / Notices 18187 

TABLE 3—ESTIMATES OF THE POSSIBLE NUMBERS OF MARINE MAMMALS EXPOSED TO DIFFERENT SOUND LEVELS ≥160 

DB DURING USGS’S PROPOSED SEISMIC SURVEY IN THE CENTRAL GOA DURING JUNE 2011.—Continued 

Species 

Estimated number 

of individuals 

exposed to sound 

levels 

≥160 dB re 1 μPa 

(Best 1) 

Estimated number 

of individuals exposed to sound 

levels 

≥160 dB re 1 μPa 

(Maximum 1) 

Requested take 

authorization 

Approximate 

percent of 

regional 

population 2

(Best) 

Pacific white-sided dolphin ............................................... NA NA NA NA 

Risso’s dolphin ................................................................. NA NA NA NA 

Killer whale ....................................................................... 82 162 162 1.0 

Short-finned pilot whale .................................................... NA NA NA NA 

Phocoenidae: 

Harbor porpoise ................................................................ NA NA NA NA 

Dall’s porpoise .................................................................. 522 1,308 1,308 <0.1 

Pinnipeds: 

Northern fur seal ............................................................... 2,771 3,325 3,325 <0.1 

Steller sea lion .................................................................. 256 308 308 0.6 

California sea lion ............................................................. NA NA NA NA 

Harbor seal ....................................................................... NA NA NA NA 

Northern elephant seal ..................................................... 0 0 0 0 

1Best and maximum estimates are based on densities from Table 3 and ensonified areas (including 25% contingency) of 26,166.25 km2 for 

160 dB. 2 Regional population size estimates are from Table 2 (see Table 2 of the IHA application); NA means not available. 

Encouraging and Coordinating 

Research 

USGS will coordinate the planned 

marine mammal monitoring program 

associated with the seismic survey in 

the central GOA with other parties that 

may have interest in the area and/or be 

conducting marine mammal studies in 

the same region during the proposed 

seismic survey. USGS will coordinate 

with applicable U.S. agencies (e.g., 

NMFS), and will comply with their 

requirements. 

Negligible Impact and Small Numbers 

Analysis and Determination 

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.’’ 

Based on the analysis contained 

herein, of the likely effects of the 

specified activity on marine mammals 

and their habitat, and taking into 

consideration the implementation of the 

mitigation and monitoring measures, 

NMFS, on behalf of the Secretary, 

preliminarily finds that USGS’s 

activities would result in the incidental 

take of marine mammals, by Level B 

harassment only, and that the total 

taking from the marine seismic survey 

in the central GOA would have a 

negligible impact on the affected species 

or stocks of marine mammals. 

For reasons stated previously in this 

document, the specified activities 

associated with the marine seismic 

survey are not likely to cause TTS, PTS, 

or other non-auditory injury, serious 

injury, or death is anticipated or 

authorized, and the potential for 

temporary or permanent hearing 

impairment is very low and will be 

minimized through the incorporation of 

the monitoring and mitigation measures. 

In making a negligible impact 

determination, NMFS evaluated factors 

such as: 

(1) The number of anticipated 

injuries, serious injuries, or mortalities; 

(2) the number, nature, and intensity, 

and duration of Level B harassment (all 

relatively limited); and 

(3) the context in which the takes 

occur (i.e., impacts to areas of 

significance, impacts to local 

populations, and cumulative impacts 

when taking into account successive/ 

contemporaneous actions when added 

to baseline data); 

(4) the status of stock or species of 

marine mammals (i.e., depleted, not 

depleted, decreasing, increasing, stable, 

impact relative to the size of the 

population); 

(5) impacts on habitat affecting rates 

of recruitment/survival; and 

(6) the effectiveness of monitoring and 

mitigation measures. 

As mentioned previously, NMFS 

estimates that nine species of marine 

mammals could be potentially affected 

by Level B harassment over the course 

of the IHA. For each species, these 

numbers are small (each, one percent or 

less) relative to the population size. 

No injuries, serious injuries, or 

mortalities are anticipated to occur as a 

result of the USGS’s planned marine 

seismic survey, and none are 

authorized. Only short-term behavioral 

disturbance is anticipated to occur due 

to the brief and sporadic duration of the 

survey activities. No mortality or injury 

is expected to occur, and due to the 

nature, degree, and context of 

behavioral harassment anticipated, the 

activity is not expected to impact rates 

of recruitment or survival. 

NMFS has preliminarily determined, 

provided that the aforementioned 

mitigation and monitoring measures are 

implemented, that the impact of 

conducting a marine geophysical survey 

in the central GOA, June, 2011, may 

result, at worst, in a temporary 

modification in behavior and/or lowlevel physiological effects (Level B 

harassment) of small numbers of certain 

species of marine mammals. 

While behavioral modifications, 

including temporarily vacating the area 

during the operation of the airgun(s), 

may be made by these species to avoid 

the resultant acoustic disturbance, the 

availability of alternate areas within 

these areas and the short and sporadic 

duration of the research activities, have 

led NMFS to preliminary determine that 

this action will have a negligible impact 

on the species in the specified 

geographic region. 

Based on the analysis contained 

herein of the likely effects of the 

specified activity on marine mammals 

and their habitat, and taking into 

consideration the implementation of the 

mitigation and monitoring measures, 

NMFS preliminarily finds that USGS’s 

planned research activities, will result 

in the incidental take of small numbers 

of marine mammals, by Level B 

harassment only, and that the total 

taking from the marine seismic survey 

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18188 Federal Register / Vol. 76, No. 63 / Friday, April 1, 2011 / Notices 

will have a negligible impact on the 

affected species or stocks. 

Impact on Availability of Affected 

Species or Stock for Taking for 

Subsistence Uses 

Section 101(a)(5)(D) also requires 

NMFS to determine that the 

authorization will not have an 

unmitigable adverse effect on the 

availability of marine mammal species 

or stocks for subsistence use. There are 

no relevant subsistence uses of marine 

mammals in the study area (deep, 

offshore waters of the central GOA) that 

implicate MMPA Section 101(a)(5)(D). 

Endangered Species Act 

Of the species of marine mammals 

that may occur in the proposed survey 

area, several are listed as endangered 

under the ESA, including the North 

Pacific right, humpback, sei, fin, blue, 

and sperm whales, as well as the Cook 

Inlet DPS of beluga whales and the 

western stock of Steller sea lions. The 

eastern stock of Steller sea lions is listed 

as threatened, as is the southwest 

Alaska DPS of the sea otter. Under 

Section 7 of the ESA, USGS has 

initiated formal consultation with the 

NMFS, Office of Protected Resources, 

Endangered Species Division, on this 

proposed seismic survey. NMFS’s Office 

of Protected Resources, Permits, 

Conservation and Education Division, 

has initiated formal consultation under 

section 7 of the ESA with NMFS’ Office 

of Protected Resources, Endangered 

Species Division, to obtain a Biological 

Opinion evaluating the effects of issuing 

the IHA on threatened and endangered 

marine mammals and, if appropriate, 

authorizing incidental take. NMFS will 

conclude formal section 7 consultation 

prior to making a determination on 

whether or not to issue the IHA. If the 

IHA is issued, USGS, in addition to the 

mitigation and monitoring requirements 

included in the IHA, will be required to 

comply with the Terms and Conditions 

of the Incidental Take Statement 

corresponding to NMFS’s Biological 

Opinion issued to both USGS and 

NMFS’s Office of Protected Resources. 

National Environmental Policy Act 

(NEPA) 

With its complete application, USGS 

provided NMFS an EA analyzing the 

direct, indirect, and cumulative 

environmental impacts of the proposed 

specified activities on marine mammals 

including those listed as threatened or 

endangered under the ESA. The EA, 

prepared by LGL on behalf of USGS is 

entitled ‘‘Environmental Assessment of a 

Marine Geophysical Survey by the R/V 

Marcus G. Langseth in the central Gulf 

of Alaska, June 2011.’’ Prior to making 

a final decision on the IHA application, 

NMFS will either prepare an 

independent EA, or, after review and 

evaluation of the USGS EA for 

consistency with the regulations 

published by the Council of 

Environmental Quality (CEQ) and 

NOAA Administrative Order 216–6, 

Environmental Review Procedures for 

Implementing the National 

Environmental Policy Act, adopt the 

USGS EA and make a decision of 

whether or not to issue a Finding of No 

Significant Impact (FONSI). 

Proposed Authorization 

NMFS proposes to issue an IHA to 

USGS for conducting a marine 

geophysical survey in the central GOA, 

provided the previously mentioned 

mitigation, monitoring, and reporting 

requirements are incorporated. The 

duration of the IHA would not exceed 

one year from the date of its issuance. 

Information Solicited 

NMFS requests interested persons to 

submit comments and information 

concerning this proposed project and 

NMFS’ preliminary determination of 

issuing an IHA (see ADDRESSES). 

Concurrent with the publication of this 

notice in the Federal Register, NMFS is 

forwarding copies of this application to 

the Marine Mammal Commission and 

its Committee of Scientific Advisors. 

Dated: March 25, 2011. 

James H. Lecky, 

Director, Office of Protected Resources, 

National Marine Fisheries Service. 

[FR Doc. 2011–7487 Filed 3–31–11; 8:45 am] 

BILLING CODE 3510–22–P 

COMMITTEE FOR PURCHASE FROM 

PEOPLE WHO ARE BLIND OR 

SEVERELY DISABLED 

Procurement List; Proposed Additions 

and Deletions 

AGENCY: Committee for Purchase From 

People Who Are Blind or Severely 

Disabled. 

ACTION: Proposed additions to and 

deletions from the Procurement List. 

SUMMARY: The Committee is proposing 

to add products and a service to the 

Procurement List that will be furnished 

by nonprofit agencies employing 

persons who are blind or have other 

severe disabilities and to delete 

products previously furnished by such 

agencies. 

Comments Must be Received on or 

Before: 5/2/2011. 

ADDRESSES: Committee for Purchase 

From People Who Are Blind or Severely 

Disabled, Jefferson Plaza 2, Suite 10800, 

1421 Jefferson Davis Highway, 

Arlington, Virginia 22202–3259. 

For Further Information or to Submit 

Comments Contact: Patricia Briscoe, 

Telephone: (703) 603–7740, Fax: (703) 

603–0655, or e-mail 

CMTEFedReg@AbilityOne.gov. 

SUPPLEMENTARY INFORMATION: This 

notice is published pursuant to 41 U.S.C 

47(a) (2) and 41 CFR 51–2.3. Its purpose 

is to provide interested persons an 

opportunity to submit comments on the 

proposed actions. 

Additions 

If the Committee approves the 

proposed additions, the entities of the 

Federal Government identified in this 

notice will be required to procure the 

products and service listed below from 

nonprofit agencies employing persons 

who are blind or have other severe 

disabilities. 

Regulatory Flexibility Act Certification 

I certify that the following action will 

not have a significant impact on a 

substantial number of small entities. 

The major factors considered for this 

certification were: 

1. If approved, the action will not 

result in any additional reporting, 

recordkeeping or other compliance 

requirements for small entities other 

than the small organizations that will 

provide the products and service to the 

Government. 

2. If approved, the action will result 

in authorizing small entities to furnish 

the products and service to the 

Government. 

3. There are no known regulatory 

alternatives which would accomplish 

the objectives of the Javits-WagnerO’Day Act (41 U.S.C. 46–48c) in 

connection with the products and 

service proposed for addition to the 

Procurement List. 

Comments on this certification are 

invited. Commenters should identify the 

statement(s) underlying the certification 

on which they are providing additional 

information. 

End of Certification 

The following products and service 

are proposed for addition to 

Procurement List for production by the 

nonprofit agencies listed: 

Products 

Towel, Highly Absorbent, Synthetic 

‘‘Shammy’’ 

NSN: 7920–01–215–6568—15x15. 

NSN: 7920–01–215–6569—20x23. 

NPA: Industries for the Blind, Inc., West 

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