Federal Register / Vol. 73, No. 151 / Tuesday, August 5, 2008 / Notices 45407 

DEPARTMENT OF COMMERCE 

National Oceanic and Atmospheric 

Administration 

RIN 0648–XI15 

Small Takes of Marine Mammals 

Incidental to Specified Activities; 

Marine Geophysical Survey in the Gulf 

of Alaska, September 2008 

AGENCY: National Marine Fisheries 

Service (NMFS), National Oceanic and 

Atmospheric Administration (NOAA), 

Commerce. 

ACTION: Notice; proposed incidental 

take authorization; request for 

comments. 

SUMMARY: NMFS has received an 

application from Lamont-Doherty Earth 

Observatory (L-DEO), a part of Columbia 

University, for an Incidental Harassment 

Authorization (IHA) to take marine 

mammals incidental to conducting a 

marine seismic survey in the Gulf of 

Alaska during September 2008. 

Pursuant to the Marine Mammal 

Protection Act (MMPA), NMFS is 

requesting comments on its proposal to 

issue an IHA to L-DEO to incidentally 

take, by Level B harassment only, small 

numbers of several species of marine 

mammals during the aforementioned 

activity. 

DATES: Comments and information must 

be received no later than September 4, 

2008. 

ADDRESSES: Comments on the 

application should be addressed to P. 

Michael Payne, Chief, Permits, 

Conservation and Education Division, 

Office of Protected Resources, National 

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

20910–3225. The mailbox address for 

providing email comments is PR1.0648–

XI15@noaa.gov. Comments sent via email, including all attachments, must 

not exceed a 10–megabyte file size. 

A copy of the application containing 

a list of the references used in this 

document may be obtained by writing to 

the address specified above, telephoning 

the contact listed below (see FOR

FURTHER INFORMATION CONTACT), or 

visiting the internet at: http:// 

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

incidental.htm#applications. 

Documents cited in this notice may be 

viewed, by appointment, during regular 

business hours, at the aforementioned 

address. 

FOR FURTHER INFORMATION CONTACT: 

Howard Goldstein or Ken Hollingshead, 

Office of Protected Resources, NMFS, 

(301) 713–2289. 

SUPPLEMENTARY INFORMATION: 

Background 

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

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

the Secretary of Commerce to allow, 

upon request, the incidental, but not 

intentional, taking of marine mammals 

by U.S. citizens who engage in a 

specified activity (other than 

commercial fishing) within a specified 

geographical region if certain findings 

are made and either regulations are 

issued or, if the taking is limited to 

harassment, a notice of a proposed 

authorization is provided to the public 

for review. 

Authorization shall be granted if 

NMFS finds that the taking will have a 

negligible impact on the species or 

stock(s), will not have an unmitigable 

adverse impact on the availability of the 

species or stock(s) for subsistence uses 

(where relevant), and if the permissible 

methods of taking and requirements 

pertaining to the mitigation, monitoring 

and reporting of such takings are set 

forth. NMFS has defined ‘‘negligible 

impact’’ in 50 CFR 216.103 as ’’ * * * 

an impact resulting from the specified 

activity that cannot be reasonably 

expected to, and is not reasonably likely 

to, adversely affect the species or stock 

through effects on annual rates of 

recruitment or survival.’’

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

established an expedited process by 

which citizens of the United States can 

apply for an authorization to 

incidentally take small numbers of 

marine mammals by harassment. Except 

with respect to certain activities not 

pertinent here, the MMPA defines 

‘‘harassment’’ as: 

any act of pursuit, torment, or annoyance 

which (I) has the potential to injure a marine 

mammal or marine mammal stock in the wild 

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

to disturb a marine mammal or marine 

mammal stock in the wild by causing 

disruption of behavioral patterns, including, 

but not limited to, migration, breathing, 

nursing, breeding, feeding, or sheltering 

[Level B harassment]. 

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

day time limit for NMFS review of an 

application followed by a 30–day public 

notice and comment period on any 

proposed authorizations for the 

incidental harassment of marine 

mammals. Within 45 days of the close 

of the comment period, NMFS must 

either approve or deny the 

authorization. 

Summary of Request 

On April 10, 2008, NMFS received an 

application from L-DEO for the taking, 

by Level B harassment only, of small 

numbers of 21 species of marine 

mammals incidental to conducting, 

under a cooperative agreement with the 

National Science Foundation (NSF), a 

seismic survey in the northeast Gulf of 

Alaska (GOA). The proposed cruise will 

take place in the territorial waters and 

Exclusive Economic Zone (EEZ) of the 

U.S. and is scheduled to occur from 31 

August to 23 September 2008. 

The purpose of the proposed seismic 

survey is to examine crustal structure, 

fault patterns, and tectonic-climate 

geohistory of the area. The proposed 

program will investigate the interplay of 

climate and tectonics onshore and 

offshore in an area that includes the 

world’s largest strike-slip earthquakes 

(Magnitude 8.0 Denali Event), largest 

earthquake caused uplift (14.4 m or 47 

ft in 1962), largest area of seismic uplift 

(during the 1962 event), highest tsunami 

(over 200 m or 656 ft in Latoya Bay in 

1958), largest temperate glaciers (the 

Malaspina and Bering Glaciers), and 

some of the highest sedimentation rates 

(over 1 m or 3.3 ft per year in some 

places). Nowhere else on the planet are 

tectonics and climate interacting to 

create this combination of mountain 

building, glacial erosion, strike-slip 

(California style), and subduction (Japan 

style) earthquakes. 

While affecting a small local 

population in the past, natural seismic 

activity in the GOA could influence the 

whole of the North Pacific basin, which 

includes many large population centers. 

Alaska is being directly affected by 

modern climate change, and new 

evidence suggests that, as climate 

changes tectonics respond and vice 

versa. This interplay could be 

fundamental to the way the Earth works 

as a system, and by examining this 

interplay, the intention of the STEEP 

program is to examine the feedbacks 

that drive the system. 

The STEEP program is 5 years in 

length and includes scientists from over 

10 universities. The study represents the 

most comprehensive study of tectonic 

and climate interactions ever 

undertaken in a single project. The 

offshore seismic component is a 

keystone for the experiment. The data 

obtained from the seismic survey will be 

used to determine the history of 

tectonic-climate interplay, as well as the 

nature of the Yakutat plate that is 

causing all of the deformation in 

southern Alaska, built the Saint Elias 

Mountains, and started the aggressive 

glaciation that continues today. 

Description of the Activity 

The seismic survey will involve one 

source vessel, the R/V Marcus G. 

Langseth (Langseth), which will occur 

offshore from the Saint Elias Mountains. 

The Langseth will deploy an array of 36 


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45408 Federal Register / Vol. 73, No. 151 / Tuesday, August 5, 2008 / Notices 

airguns (6,600 in3) as an energy source 

and, at times, a receiving system 

consisting of one 8–km (3.7–mi) towed 

hydrophone streamer. The streamer will 

be towed at a depth of 7 m (23 ft) and 

the airguns at 9 m (29.5 ft). The 

Langseth will also deploy Ocean Bottom 

Seismometers (OBSs) to receive the 

returning acoustic signals. The OBSs are 

housed in 43–cm diameter glass spheres 

that have a gross weight of 

approximately 45 kg (99 lbs). As the 

airgun array is towed along the survey 

lines, the hydrophone streamer and/or 

OBSs will receive the returning acoustic 

signals and transfer the data to the onboard processing system. 

The Langseth is expected to depart 

Prince Rupert, British Columbia, 

Canada, on approximately 31 August, 

2008 for the study area in the GOA (see 

Figure 1 of L-DEO’s application). The 

airgun array is expected to operate for 

a total of ∼200–250 hours. With OBS 

deployment and retrieval, the length of 

the survey will be ∼18 days. The overall 

area within which the STEEP survey 

will take place is located at ∼58–60.5° N, 

138–146° W (see Figure 1 of L-DEO’s 

application). The proposed survey will 

be conducted in water depths from <100 

m to >3,000 m (<330 to>9,840 ft) 

entirely within the territorial waters and 

Exclusive Economic Zone (EEZ) of the 

United States. The exact dates of the 

activities depend upon logistics, as well 

as weather conditions and/or the need 

to repeat some lines if data quality is 

substandard. 

The primary marine seismic survey 

will consist of two long transect lines 

that will cross each other (Figure 1 of LDEO’s application). For the longer line 

paralleling the shoreline, a seismic 

reflection-refraction profile will be shot 

using the hydrophone streamer as well 

as 25 OBSs deployed on the seafloor 

and 60 Texan seismometers deployed 

on land across the toe of the Bering 

Glacier. A reflection-refraction profile 

will also be obtained from the slightly 

shorter line that is perpendicular to the 

shoreline using the hydrophone 

streamer as well as 17 OBSs; this line 

will be shot twice if time allows. Both 

of these lines will have a shot spacing 

of 50 m (164 ft, 20 seconds); if the 

onshore-offshore line is shot twice, the 

shot interval used during the second run 

will be 150 m (492 ft, 60 s). During the 

reflection-refraction profiling, the airgun 

array will be towed at a depth of 9 m. 

In addition, two reflection-only 2–

dimensional (2–D) seismic grids will be 

shot; the western grid is located 

approximately 150 km (93 mi) from 

shore whereas the eastern grid is located 

nearshore (see Figure 1 in L-DEO’s 

application). The shot spacing for these 

grids will be 50 m (164 ft) and the 

airgun array will be towed at a depth of 

9 m. No OBSs will be deployed during 

reflection-only profiling. There will be 

additional operations associated with 

equipment testing, startup, line changes, 

and repeat coverage of any areas where 

initial data quality is sub-standard. In LDEO’s calculations, 25% has been 

added to the line total for those 

additional operations. 

The planned seismic survey 

(excluding the 25 percent contingency) 

will consist of 1909 km of survey lines 

including turns (see Figure 1 in L-DEO’s 

application). Most of this effort (923 km 

or 574 mi) will take place in 

intermediate water depths of 100–1,000 

m and in water depths >1,000 m deep 

(812 km or 504 mi), and a smaller 

portion (174 km or 108 mi) will take 

place in water <100 m deep. 

All planned geophysical data 

acquisition activities will be conducted 

by L-DEO with on-board assistance by 

the scientists who have proposed the 

study. The scientific team is headed by 

Dr. Sean Gullick of the University of 

Texas at Austin Institute for Geophysics 

(UTIG) and also includes Drs. G. 

Christesen, P. Mann, and H. Van 

Avendonk of UTIG. The vessel will be 

self-contained, and the crew will live 

aboard the vessel for the entire cruise. 

In addition to the operations of the 

airgun array, a multibeam echosounder 

(MBES) will be operated from the 

Langseth continuously throughout the 

STEEP cruise. Also, a sub-bottom 

profiler (SBP) will be operated by the 

Langseth during most of the survey. 

Vessel Specifications 

The Langseth has a length of 71.5 m 

(234.6 ft), a beam of 17 m (55.8 ft), and 

a maximum draft of 5.9 m (19.4 ft). The 

ship was designed as a seismic research 

vessel, with a propulsion system 

designed to be as quiet as possible to 

avoid interference with the seismic 

signals. The ship is powered by two 

Bergen BRG–6 diesel engines, each 

producing 3,550 hp, that drive the two 

propellers directly. Each propeller has 

four blades, and the shaft typically 

rotates at 750 rpm. The vessel also has 

an 800–hp bowthruster. The operation 

speed during seismic acquisition is 

typically 7.4–9.3 km/h (4–5 kt). When 

not towing seismic survey gear, the 

Langseth can cruise at 20–24 km/h (11–

13 kt). The Langseth has a range of 

25,000 km (15,534 mi). The Langseth 

will also serve as the platform from 

which vessel-based marine mammal 

(and sea turtle) observers (MMOs) will 

watch for animals before and during 

airgun operations. 

Acoustic Source Specifications 

Seismic Airguns 

During the proposed survey, the 

airgun array to be used will consist of 

36 airguns, with a total volume of 

approximately 6,600 in3. The airguns 

will consist of a mixture of Bolt 1500LL 

and 1900LL airguns. The airguns array 

will be configured as four identical 

linear arrays or ‘‘strings’’ (see Figure 2 

in L-DEO’s application). Each string will 

have ten airguns; the first and last 

airguns in each string are spaced 16 m 

(52.5 ft) apart. Nine airguns in each 

string will be fired simultaneously, 

while the tenth is kept in reserve as a 

spare, to be turned on in case of failure 

of another airgun. The four airgun 

strings will be distributed across an 

approximate area of 24 x 16 m (78.7 x 

52.5 ft) behind the Langseth and will be 

towed approximately 50–100 m (164–

328 ft) behind the vessel at 9–m depth. 

The firing pressure of the array is 2,000 

psi. The airgun array will fire in two 

modes: every 50 m (164 ft; 20 s) or every 

150 m (492 ft; 60 s). During firing, a 

brief (approximately 0.1 s) pulse of 

sound is emitted. The airguns will be 

silent during the intervening periods. 

Because the actual source is a 

distributed sound source (36 airguns) 

rather than a single point source, the 

highest sound levels measurable at any 

location in the water will be less than 

the nominal source level (265 dB re 1 

μPa.m, peak to peak). In addition, the 

effective source level for sound 

propagating in near-horizontal 

directions will be substantially lower 

than the nominal source level 

applicable to downward propagation 

because of the directional nature of the 

sound from the airgun array. 

Sound propagation has been 

predicted by L-DEO for the 36–airgun 

array operating in deep, intermediate, 

and shallow water and for a single 

1900LL 40 in3 airgun (which will be 

used during power downs), in relation 

to distance and direction from the 

airguns (See Table 1). A detailed 

description of L-DEO’s modeling effort 

is provided in Appendix A of the 

application. 

Multibeam Echosounder 

The Simrad EM120 operates at 11.25–

12.6 kHz and is hull-mounted on the 

Langseth. The beamwidth is 1° fore-aft 

and 150° athwartship. The maximum 

source level is 242 dB re 1 μPa (rms; 

Hammerstad, 2005). For deep-water 

operation, each ‘‘ping’’ consists of nine 

successive fan-shaped transmissions, 

each 15 ms in duration and each 

ensonifying a section that extends 1° 

fore-aft. The nine successive 


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

16 ms gaps between the pulses for 

successive sectors. A receiver in the 

overlap area between the two sectors 

would receive two 15–ms pulses 

separated by a 16–ms gap. In shallower 

water, the pulse duration is reduced to 

5 or 2 ms, and the number of transmit 

beams is also reduced. The ping interval 

varies with water depth, from 

approximately 5 s at 1,000 m (3,280 ft) 

to 20 s at 4,000 m (13,123 ft; Kongsberg 

Maritime, 2005). 

Sub-bottom Profiler 

The SBP is normally operated to 

provide information about the 

sedimentary features and the bottom 

topography that is simultaneously being 

mapped by the MBES. The energy from 

the SBP is directed downward by a 3.5 

kHz transducer in the hull of the 

Langseth. The output varies with water 

depth from 50 watts in shallow water to 

800 watts in deep water. The pulse 

interval is 1 s, but a common mode of 

operation is to broadcast five pulses at 

1–s intervals followed by a 5–s pause. 

Source and Volume Tow Depth (m) Water Depth 

Predicted RMS Distances (m) 

190 dB 180 dB 160 dB 

Single Bolt airgun Deep 12 40 385 

9 Intermediate 18 60 578 

40 in3 Shallow 150 296 1050 

4 strings Deep 300 950 6000 

36 airguns 9 Intermediate 450 1425 6667 

6600 in3 Shallow 2182 3694 8000 

Table 1. Predicted distances to which sound levels ≥190, 180, and 160 dB re 1 μPa might be received in shallow (<100 m; 328 ft), intermediate (100-1,000 m; 328-3,280 ft), and deep (>1,000 m; 3,280 ft) water during the Central American SubFac and STEEP Gulf of Alaska 

survey. 

Because the predictions in Table 1 are 

based in part on empirical correction 

factors derived from acoustic calibration 

of different airgun configurations than 

those to be used on the Langseth (cf. 

Tolstoy et al., 2004a,b), L-DEO 

conducted an acoustic calibration study 

of the Langseth’s 36–airgun 

(approximately 6,600 in3) array in late 

2007/early 2008 in the Gulf of Mexico 

(LGL Ltd. 2006). Distances where sound 

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

μPa rms) were received in deep, 

intermediate, and shallow water will be 

determined for various airgun 

configurations. Acoustic data analysis is 

ongoing. After, analysis, the empirical 

data from the 2007/2008 calibration 

study will be used to refine the 

exclusion zones proposed above for use 

during the STEEP cruise, if the data are 

appropriate and available for use at the 

time of the survey. 

Description of Marine Mammals in the 

Activity Area 

A total of 18 cetacean species, 3 

species of pinnipeds, and the sea otter 

are known to or could occur in the GOA 

study area (see Table 2 of the 

application; Angliss and Outlaw, 2007). 

Several of the species are listed as 

Endangered under the U.S. Endangered 

Species Act (ESA), including the 

humpback, sei, fin, blue, North Pacific 

right, and sperm whale, sea otter, and 

the western stock of Steller sea lions. 

The eastern stock of Steller sea lions is 

listed as Threatened. The southeast 

Alaska Distinct Population Segment of 

northern sea otters are also listed as 

Threatened. There is little information 

on the distribution of marine mammals 

inhabiting the waters offshore of SE 

Alaska or the eastern GOA, although a 

few reports are available (e.g., Buckland 

et al., 1993; Hobbs and Lerczak, 1993; 

Straley et al. 1995; Calambokidis et al., 

1997; MacLean and Koski, 2005; Angliss 

and Outlaw, 2007). 

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 and 

sea lions), and fissipeds (the sea otter). 

Cetaceans and pinnipeds are managed 

by NMFS and are the subject of this IHA 

application. Several of the 18 cetacean 

species are common in the area (see 

below). Of the three species of 

pinnipeds that potentially could occur 

in the study area, only the Steller sea 

lion and harbor seal are likely to be 

present. The northern fur seal inhabits 

the Bering Sea during the summer, and 

is generally found in SE Alaska in low 

numbers during the winter and during 

the northward migration in the spring. 

Sea otters are managed by the U.S. Fish 

and Wildlife Service (USFWS). Informal 

consultation with the USFWS is being 

sought for sea otters. 

Information on the occurrence, 

distribution, population size, habitat, 

and conservation status for each of the 

21 marine mammal species that are 

likely to occur in the proposed project 

area is presented in Table 5 of L-DEO’s 

application and is reprinted in part here 

as Table 2. 

Based on a compilation of data from 

1979 to 2001, many cetaceans and 

pinnipeds occur within the EEZ in both 

oceanic and coastal waters. However, 

beaked, sperm, dwarf/pygmy sperm, 

and baleen whales (except for the 

humpback) occur predominantly in 

oceanic waters (May-Collado et al., 

2005). Bottlenose and pantropical 

spotted dolphins, as well as the 

humpback whale, tend to be coastal. 

Table 2 below outlines the cetacean 

and pinniped species, their habitat and 

abundance in the proposed project area, 

and the requested take levels. 

Additional information regarding the 

distribution of these species expected to 

be found in the project area and how the 

estimated densities were calculated may 

be found in L-DEO’s application. 

Species Habitat Abundance (Alaska) Regional Abundance ESA 1

Odontocetes 


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45410 Federal Register / Vol. 73, No. 151 / Tuesday, August 5, 2008 / Notices 

Species Habitat Abundance (Alaska) Regional Abundance ESA 1

Sperm whale (Physeter 

macrocephalus) 

Pelagic 159 4 24,000 5 EN 

Cuvier’s beaked whale (Ziphius 

cavirostris) 

Pelagic N.A. 20,000 6 N.L. 

Baird’s beaked whale 

(Berardius bairdii) 

Pelagic N.A. 6,000 7 N.L. 

Stejneger’s beaked whale 

(Mesoplodon stejnegeri) 

Likely Pelagic N.A. N.A. N.L. 

Beluga whale (Delphinapterus 

leucas) 

Coastal & Ice Edges 366 8 N.A. N.L. 

Pacific white-sided dolphin 

(Lagenorhynchus 

obliquidens) 

Pelagic, Shelf, Coastal 26,880 9 931,000 10 N.L. 

Risso’s dolphin (Grampus 

griseus) 

Pelagic, Shelf, Coastal N.A. 16,066 11 N.L. 

Killer whale (Orcinus orca) Pelagic, Shelf, Coastal 1,975 12 8,500 13 N.L. 

Short-finned pilot whale 

(Globicephala 

macrorhynchus) 

Pelagic, Shelf, Coastal N.A. 160,200 6 N.L. 

Harbor Porpoise (Phocoena 

phocoena) 

Coastal 17,076 14

41,854 15

202,988 16 N.L. 

Dall’s Porpoise (Phocoenoides 

dalli) 

Pelagic & Shelf 83,400 17 1,186,000 18 N.L. 

Mysticetes 

Humpback whale (Megaptera 

novaeangliae) 

Coastal & Banks 2,644 21 >6,000 22 EN 

Minke whale (Balaenoptera 

acutorostrata) 

Coastal & Shelf 1,232 21 9,000 23 N.L. 

Gray whale (Eschrichtius 

robustus) 

Coastal N.A. 18,813 20 N.L. 

Sei whale (Balaenoptera borealis) Pelagic N.A. 7,260-12,620 22 EN 

Fin whale (Balaenoptera 

physalus) 

Pelagic 1,652 24 13,620-18,680 22 EN 

Blue whale (Balaenoptera 

musculus) 

Pelagic, Shelf, Coastal N.A. 1,744 11 EN 

North Pacific right whale 

(Eubalaena japonica) 

Coastal & Shelf N.A. 100-200 19 EN 

Pinnipeds 

Northern fur seal (Callorhinus 

ursinus) 

Pelagic, Breeds Coastally N.A. 721,935 25 N.L. 

Steller sea lion (Eumetopias 

jubatus) 

Coastal 47,885 26

44,780 27

N.A. T 

EN 

Harbor seal (Phoca vitulina 

richardsi) 

Coastal 180,017 28 N.A. N.L. 

Table 2. The habitat, abundance, and conservation status of marine mammals inhabiting the proposed study area in the Gulf of Alaska. Regional abundance estimates are also given, usually for the Northeastern Pacific Ocean or the U.S. West Coast. 

Note: N.A. = Not available or not applicable. 

1 U.S. Endangered Species Act. En = Endangered; T = Threatened; N.L. = Not Listed. 2 IUCN Red List of Threatened Species (2007). Codes for IUCN classifications: CR = Critically Endangered; EN = Endangered; VU = Vulnerable; LR = Lower Risk (-cd = Conservation Dependent; -nt = Near Threatened; -ic = Least Concern); DD = Data Deficient; NL = Not Listed. 3 Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) (UNEP-WCMC 2007). I and II are CITES Appendices; NL = Not Listed. 


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4 Western GOA and eastern Aleutians (Zerbini et al., 2004). 5 Eastern temperate North Pacific (Whitehead, 2002). 6 Eastern Tropical Pacific (Wade and Gerrodette, 1993). 7 Western North Pacific (Reeves and Leatherwood, 1994; Kasuya, 2002). 8 Cook Inlet stock (Rugh et al., 2005a). 9 GOA (Angliss and Outlaw, 2007). 10 North Pacific Ocean (Buckland et al., 1993). 11 California/Oregon/Washington (Carretta et al. 2007). 12 Minimum abundance in Alaskan waters, includes 1,339 resident and 636 transient (Angliss and Outlaw, 2007). 13 Eastern Tropical Pacific (Ford, 2002). 14 SE Alaska stock (Angliss and Outlaw, 2007). 15 GOA stock (Angliss and Outlaw 2007). 16 Western North Pacific Ocean (totals from Carretta et al., 2007 and Angliss and Outlaw, 2007). 17 Alaska stock (Angliss and Outlaw, 2007). 18 North Pacific Ocean and Bering Sea (Houk and Jefferson, 1999). 19 Eastern North Pacific (Wada, 1973). 20 Mean of 2000-2001 and 2001-2002 abundance estimates for eastern North Pacific (Angliss and Outlaw, 2007). 21 Western GOA and eastern Aleutians (Zerbini et al., 2006). 22 North Pacific Ocean (Carretta et al., 2007). 23 North Pacific Ocean (Wada, 1976). 24 Central waters of western Alaska and eastern and central Aleutian Islands (Angliss and Outlaw, 2007). 25 Abundance for Eastern Pacific Stock (Angliss and Outlaw, 2007). 26 Eastern U.S. Stock (Angliss and Outlaw, 2007). 27 Western U.S. Stock (Angliss and Outlaw, 2007). 28 Alaska statewide (Angliss and Outlaw, 2007). 29 Abundance estimate for SE Alaska stock (USFWS 2002 in Angliss and Outlaw, 2007). 30 Abundance estimate Southcentral Alaska (USFWS 2002 in Angliss and Outlaw, 2007). 31 SW Alaska stock (USFWS 2002 in Angliss and Outlaw, 2007). 

Potential Effects on Marine Mammals 

Potential Effects of Airguns 

The effects of sounds from airguns 

might include one or more of the 

following: tolerance, masking of natural 

sounds, behavioral disturbances, and 

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). With the possible 

exception of some cases of temporary 

threshold shift in harbor seals, it is 

unlikely that the project would result in 

any cases of temporary or especially 

permanent hearing impairment, or any 

significant non-auditory physical or 

physiological effects. Some behavioral 

disturbance is expected, but this would 

be localized and short-term. 

The rms (root mean square) received 

levels that are used as impact criteria for 

marine mammals are not directly 

comparable to the peak or peak-to-peak 

values normally used to characterize 

source levels of airgun arrays. The 

measurement units used to describe 

airgun sources, peak or peak-to-peak 

decibels, are always higher than the rms 

decibels referred to in biological 

literature. A measured received level of 

160 dB rms in the far field would 

typically correspond to a peak 

measurement of approximately 170 to 

172 dB, and to a peak-to-peak 

measurement of approximately 176 to 

178 dB, as measured for the same pulse 

received at the same location (Greene, 

1997; McCauley et al., 1998, 2000a). The 

precise difference between rms and 

peak or peak-to-peak values depends on 

the frequency content and duration of 

the pulse, among other factors. 

However, the rms level is always lower 

than the peak or peak-to-peak level for 

an airgun-type source. 

Tolerance 

Numerous studies have shown that 

pulsed sounds from airguns are often 

readily detectable in the water at 

distances of many kilometers. For a 

summary of the characteristics of airgun 

pulses, see Appendices B ) of L-DEO’s 

application. Numerous studies have 

shown that marine mammals at 

distances more than a few kilometers 

from operating seismic vessels often 

show no apparent response see 

Appendix C (e) of the application. That 

is often true even in cases when the 

pulsed sounds must be readily audible 

to the animals based on measured 

received levels and the hearing 

sensitivity of the mammal group. 

Although various baleen whales, 

toothed whales, and (less frequently) 

pinnipeds have been shown to react 

behaviorally to airgun pulses under 

some conditions, at other times, 

mammals of all three types have shown 

no overt reactions. In general, pinnipeds 

usually seem to be more tolerant of 

exposure to airgun pulses than are 

cetaceans, with relative responsiveness 

of baleen and toothed whales being 

variable. 

Masking 

Obscuring of sounds of interest by 

interfering sounds, generally at similar 

frequencies, is known as masking. 

Masking effects of pulsed sounds (even 

from large arrays of airguns) on marine 

mammal calls and other natural sounds 

are expected to be limited, although 

there are few specific data of relevance. 

Because of the intermittent nature and 

low duty cycle of seismic pulses, 

animals can emit and receive sounds in 

the relatively quiet intervals between 

pulses. Some baleen and toothed whales 

are known to continue calling in the 

presence of seismic pulses. The airgun 

sounds are pulsed, with quiet periods 

between the pulses, and whale calls 

often can be heard between the seismic 

pulses (Richardson et al., 1986; 

McDonald et al., 1995; Greene et al., 

1999; Nieukirk et al., 2004; Smultea et 

al., 2004). Although there has been one 

report that sperm whales cease calling 

when exposed to pulses from a very 

distant seismic ship (Bowles et al., 

1994), a more recent study reports that 

sperm whales off northern Norway 

continued calling in the presence of 

seismic pulses (Madsen et al., 2002). 

That has also been shown during recent 

work in the Gulf of Mexico and 

Caribbean Sea (Smultea et al., 2004; 

Tyack et al., 2006). Masking effects of 

seismic pulses are expected to be 

negligible in the case of the small 

odontocetes given the intermittent 

nature of seismic pulses. Dolphins and 

porpoises commonly are heard calling 

while airguns are operating (Gordon et 

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

al., 2005a,b). Also, the sounds important 

to small odontocetes are predominantly 

at much higher frequencies than the 

airgun sounds, thus further limiting the 

potential for masking. Masking effects, 

in general, are discussed further in 

Appendix B (d) of L-DEO’s application. 


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Disturbance Reactions 

Disturbance includes a variety of 

effects, including subtle changes in 

behavior, more conspicuous changes in 

activities, and displacement. Reactions 

to sound, if any, depend on species, 

state of maturity, experience, current 

activity, reproductive state, time of day, 

and many other factors. If a marine 

mammal responds to an underwater 

sound by changing its behavior or 

moving a small distance, the response 

may or may not rise to the level of 

‘‘harassment,’’ let alone affect the stock 

or the species as a whole. However, if 

a sound source displaces marine 

mammals from an important feeding or 

breeding area for a prolonged period, 

impacts on animals or on the stock or 

species could potentially be significant. 

Given the many uncertainties in 

predicting the quantity and types of 

impacts of noise on marine mammals, it 

is common practice to estimate how 

many mammals are likely to be present 

within a particular distance of industrial 

activities, or exposed to a particular 

level of industrial sound. This practice 

potentially overestimates the numbers 

of marine mammals that are affected in 

some biologically-important manner. 

The sound exposure thresholds that 

affect marine mammals behaviorally are 

based on behavioral observations during 

studies of several species. However, 

information is lacking for many species. 

Detailed studies have been done on 

humpback, gray, and bowhead whales 

and on ringed seals. Less detailed data 

are available for some other species of 

baleen whales, sperm whales, and small 

toothed whales. 

Baleen Whales – Baleen whales 

generally tend to avoid operating 

airguns, but avoidance radii are quite 

variable. Whales are often reported to 

show no overt reactions to pulses from 

large arrays of airguns at distances 

beyond a few kilometers, even though 

the airgun pulses remain well above 

ambient noise levels out to much longer 

distances. However, as reviewed in 

Appendix B (e) of L-DEO’s application, 

baleen whales exposed to strong noise 

pulses from airguns often react by 

deviating from their normal migration 

route and/or interrupting their feeding 

activities and moving away from the 

sound source. In the case of the 

migrating gray and bowhead whales, the 

observed changes in behavior appeared 

to be of little or no biological 

consequence to the animals. They 

simply avoided the sound source by 

displacing their migration route to 

varying degrees, but within the natural 

boundaries of the migration corridors. 

Studies of gray, bowhead, and 

humpback whales have determined that 

received levels of pulses in the 160–170 

dB re 1 μPa rms range seem to cause 

obvious avoidance behavior in a 

substantial fraction of the animals 

exposed. In many areas, seismic pulses 

from large arrays of airguns diminish to 

those levels at distances ranging from 

4.5–14.5 km (2.8–9 mi) from the source. 

A substantial proportion of the baleen 

whales within those distances may 

show avoidance or other strong 

disturbance reactions to the airgun 

array. Subtle behavioral changes 

sometimes become evident at somewhat 

lower received levels. 

Responses of humpback whales to 

seismic surveys have been studied 

during migration and on the summer 

feeding grounds, and there has also been 

discussion of effects on the Brazilian 

wintering grounds. McCauley et al. 

(1998, 2000) studied the responses of 

humpback whales off Western Australia 

to a full-scale seismic survey with a 16–

airgun, 2,678–in3 array, and to a single 

20–in3 airgun with a source level of 227 

dB re 1 μPa m peak-to-peak. McCauley 

et al. (1998) documented that initial 

avoidance reactions began at 5–8 km 

(3.1–5 mi) from the array, and that those 

reactions kept most pods approximately 

3–4 km (1.9–2.5 mi) from the operating 

seismic boat. McCauley et al. (2000) 

noted localized displacement during 

migration of 4–5 km (2.5–3.1 mi) by 

traveling pods and 7–12 km (4.3–7.5 mi) 

by cow-calf pairs. Avoidance distances 

with respect to the single airgun were 

smaller (2 km (1.2 mi)) but consistent 

with the results from the full array in 

terms of received sound levels. Mean 

avoidance distance from the airgun 

corresponded to a received sound level 

of 140 dB re 1 μPa (rms); that was the 

level at which humpbacks started to 

show avoidance reactions to an 

approaching airgun. The standoff range, 

i.e., the closest point of approach of the 

whales to the airgun, corresponded to a 

received level of 143 dB re 1 μPa (rms). 

However, some individual humpback 

whales, especially males, approached 

within distances of 100–400 m (328–

1,312 ft), where the maximum received 

level was 179 dB re 1 μPa (rms). 

Humpback whales on their summer 

feeding grounds in southeast summering 

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 150–169 dB re 1 μPa 

on an approximate rms basis. Malme et 

al. (1985) concluded that there was no 

clear evidence of avoidance, despite the 

possibility of subtle effects, at received 

levels up to 172 re 1 μPa on an 

approximate rms basis. 

It has been suggested that South 

Atlantic humpback whales wintering off 

Brazil may be displaced or even strand 

upon exposure to seismic surveys (Engel 

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

circumstantial, subject to alternative 

explanations (IAGC 2004), and not 

consistent with results from direct 

studies of humpbacks exposed to 

seismic surveys in other areas and 

seasons. After allowance for data from 

subsequent years, there was ‘‘no 

observable direct correlation’’ between 

strandings and seismic surveys (IWC 

2007:236). 

Results from bowhead whales show 

that responsiveness of baleen whales to 

seismic surveys can be quite variable 

depending on the activity (migrating vs. 

feeding) of the whales. Bowhead whales 

migrating west across the Alaskan 

Beaufort Sea in autumn, in particular, 

are unusually responsive, with 

substantial avoidance occurring out to 

distances of 20 30 km (12.4–18.6 mi) 

from a medium-sized airgun source, 

where received sound levels were on 

the order of 130 dB re 1 μPa (rms) 

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

1999; see Appendix B (e) of L-DEO’s 

application). However, more recent 

research on bowhead whales (Miller et 

al., 2005a; Harris et al., 2007) 

corroborates earlier evidence that, 

during the summer feeding season, 

bowheads are not as sensitive to seismic 

sources. In summer, bowheads typically 

begin to show avoidance reactions at a 

received level of about 160 170 dB re 1 

μPa (rms) (Richardson et al., 1986; 

Ljungblad et al., 1988; Miller et al., 

2005a). Nonetheless, statistical analysis 

showed evidence of subtle changes in 

surfacing, respiration and diving cycles 

when feeding bowheads were exposed 

to lower-level pulses from distant 

seismic operations (Richardson et al., 

1986). 

Reactions of migration 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. Malme et al. (1986, 

1988) estimated, based on small sample 

sizes, that 50 percent of feeding gray 

whales ceased feeding at an average 

received pressure level of 173 dB re 1 

μPa on an (approximate) rms basis, and 

that 10 percent of feeding whales 

interrupted feeding at received levels of 

163 dB. Those findings were generally 

consistent with the results of 

experiments conducted on larger 

numbers of gray whales that were 


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migrating along the California coast 

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

1985), and with observations of Western 

Pacific gray whales feeding off Sakhalin 

Island, Russia, when a seismic survey 

was underway just offshore of their 

feeding area (Gailey et al., 2007; 

Johnson et al., 2007; Yazvenko et al. 

2007a,b). 

Various species of Balaenoptera (blue, 

sei, fin, and minke whales) have 

occasionally been reported in areas 

ensonified by airgun pulses. Sightings 

by observers on seismic vessels off the 

United Kingdom from 1997 to 2000 

suggest that, at times of good 

sightability, numbers of rorquals seen 

are similar when airguns are shooting 

and not shooting (Stone, 2003; Stone 

and Tasker, 2006). Although individual 

species did not show any significant 

displacement in relation to seismic 

activity, all baleen whales combined 

were found to remain significantly 

further from the airguns during shooting 

compared with periods without 

shooting (Stone, 2003; Stone and 

Tasker, 2006). In a study off Nova 

Scotia, Moulton and Miller (in press) 

found only a little or no difference in 

sighting rates and initial sighting 

distances of balaenopterid whales when 

airguns were operating vs. silent. 

However, there were indications that 

these whales were more likely to be 

moving away when seen during airgun 

operations. 

Data on short-term reactions (or lack 

of reactions) of cetaceans to impulsive 

noises do not necessarily provide 

information about long-term effects. It is 

not known whether impulsive noises 

affect reproductive rate or distribution 

and habitat use in subsequent days or 

years. However, gray whales continued 

to migrate annually along the west coast 

of North America despite intermittent 

seismic exploration and much ship 

traffic in that area for decades (see 

Appendix A in Malme et al., 1984). The 

western Pacific gray whale population 

did not seem affected by a seismic 

survey in its feeding ground during a 

prior year (Johnson et al., 2007). 

Bowhead whales continued to travel to 

the eastern Beaufort Sea each summer 

despite seismic exploration in their 

summer and autumn range for many 

years (Richardson et al., 1987). In any 

event, brief exposures to sound pulses 

from the proposed airgun source are 

highly unlikely to result in prolonged 

effects. 

Toothed Whales – Little systematic 

information is available about reactions 

of toothed whales to noise pulses. Few 

studies similar to the more extensive 

baleen whale/seismic pulse work 

summarized above have been reported 

for toothed whales. However, a 

systematic study on sperm whales has 

been done ( Jochens and Biggs, 2003; 

Tyack et al., 2003; Jochens et al., 2006; 

Miller et al., 2006), and there is an 

increasing amount of information about 

responses of various odontocetes to 

seismic surveys based on monitoring 

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

2004; Moulton and Miller, 2005; Bain 

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

Stone and Tasker, 2006). 

Seismic operators and marine 

mammal observers sometimes see 

dolphins and other small toothed 

whales near operating airgun arrays, but 

in general there seems to be a tendency 

for most delphinids to show some 

limited avoidance of seismic vessels 

operating large airgun systems. 

However, some dolphins seem to be 

attracted to the seismic vessel and 

floats, and some ride the bow wave of 

the seismic vessel even when large 

airgun arrays are firing. Nonetheless, 

there have been indications that small 

toothed whales sometimes tend to head 

away or to maintain a somewhat greater 

distance from the vessel, when a large 

array of airguns is operating than when 

it is silent (e.g., Goold, 1996a,b,c; 

Calambokidis and Osmek, 1998; Stone, 

2003; Stone and Tasker, 2006). In most 

cases, the avoidance radii for delphinids 

appear to be small, on the order of 1 km 

(0.62 mi) or less. The beluga may be a 

species that (at least at times) shows 

long-distance avoidance of seismic 

vessels. Aerial surveys during seismic 

operations in the southeastern Beaufort 

Sea recorded much lower sighting rates 

of beluga whales within 10–20 km (6.2–

12.4 mi) of an active seismic vessel. 

These results were consistent with the 

low number of beluga sightings reported 

by observers aboard the seismic vessel, 

suggesting that some belugas might be 

avoiding the seismic operations at 

distances of 10–20 km (6.2–12.4 mi) 

(Miller et al., 2005a). 

Captive bottlenose dolphins and 

beluga whales exhibited changes in 

behavior when exposed to strong pulsed 

sounds similar in duration to those 

typically used in seismic surveys 

(Finneran et al., 2000, 2002, 2005; 

Finneran and Schlundt, 2004). The 

animals tolerated high received levels of 

sound (pk-pk level >200 dB re 1 μPa) 

before exhibiting aversive behaviors. For 

pooled data at 3, 10, and 20 kHz, sound 

exposure levels during sessions with 25, 

50, and 75 percent altered behavior 

were 180, 190, and 199 dB re 1 μPa2, 

respectively (Finneran and Schlundt, 

2004). 

Results for porpoises depend on 

species. Dall’s porpoises seem relatively 

tolerant of airgun operations (MacLean 

and Koski, 2005) and, during a survey 

with a large airgun array, tolerated 

higher noise levels than did harbor 

porpoises and gray whales (Bain and 

Williams, 2006). However, Dall’s 

porpoises do respond to the approach of 

large airgun arrays by moving away 

(Calambokidis and Osmek, 1998; Bain 

and Williams, 2006). The limited 

available data suggest that harbor 

porpoises show stronger avoidance 

(Stone, 2003; Bain and Williams, 2006; 

Stone and Tasker, 2006). This apparent 

difference in responsiveness of these 

two porpoise species is consistent with 

their relative responsiveness to boat 

traffic and some other acoustic sources 

in general (Richardson et al., 1995; 

Southall et al. 2007). 

Most studies of sperm whales exposed 

to airgun sounds indicate that this 

species shows considerable tolerance of 

airgun pulses. In most cases, the whales 

do not show strong avoidance and 

continue to call (see Appendix B of LDEO’s application). However, controlled 

exposure experiments in the Gulf of 

Mexico indicate that foraging effort is 

somewhat reduced upon exposure to 

airgun pulses from a seismic vessel 

operating in the area, and there may be 

a delay in diving to foraging depth 

(Miller et al., 2006; Tyack et al., 2006). 

There are no specific data on the 

behavioral reactions of beaked whales to 

seismic surveys. Most beaked whales 

tend to avoid approaching vessels of 

other types (Wursig et al., 1998). They 

may also dive for an extended period 

when approached by a vessel (Kasuya, 

1986). It is likely that these beaked 

whales would normally show strong 

avoidance of an approaching seismic 

vessel, but this has not been 

documented explicitly. 

Odontocete reactions to large arrays of 

airguns are variable and, at least for 

delphinids and Dall’s porpoises, seem to 

be confined to a smaller radius than has 

been observed for the more responsive 

of the mysticetes, belugas, and harbor 

porpoises (Appendix B of L-DEO’s 

application). 

Pinnipeds – Pinnipeds are not likely 

to show a strong avoidance reaction to 

the airgun sources that will be used. 

Visual monitoring from seismic vessels, 

usually employing larger sources, has 

shown only slight (if any) avoidance of 

airguns by pinnipeds, and only slight (if 

any) changes in behavior (see Appendix 

B(e) of L-DEO’s application). Ringed 

seals frequently do not avoid the area 

within a few hundred meters of 

operating airgun arrays (Harris et al., 

2001; Moulton and Lawson, 2002; 

Miller et al., 2005a). However, initial 

telemetry work suggests that avoidance 

and other behavioral reactions by two 


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other species of seals to small airgun 

sources may at times be stronger than 

evident to date from visual studies of 

pinniped reactions to airguns 

(Thompson et al., 1998). Even if 

reactions of any pinnipeds that might be 

encountered in the present study area 

are as strong as those evident in the 

telemetry study, reactions are expected 

to be confined to relatively small 

distances and durations, with no longterm effects on pinniped individuals or 

populations. 

Additional details on the behavioral 

reactions (or the lack thereof) by all 

types of marine mammals to seismic 

vessels can be found in Appendix B (e) 

of L-DEO’s application. 

Hearing Impairment and Other Physical 

Effects 

Temporary or permanent hearing 

impairment is a possibility when marine 

mammals are exposed to very strong 

sounds, but there has been no specific 

documentation of this for marine 

mammals exposed to sequences of 

airgun pulses. 

NMFS will be developing new noise 

exposure criteria for marine mammals 

that take account of the now-available 

scientific data on TTS, the expected 

offset between the TTS and permanent 

threshold shift (PTS) thresholds, 

differences in the acoustic frequencies 

to which different marine mammal 

groups are sensitive, and other relevant 

factors. Detailed recommendations for 

new science-based noise exposure 

criteria were published in early 2008 

(Southall et al., 2007). 

Several aspects of the planned 

monitoring and mitigation measures for 

this project (see below) are designed to 

detect marine mammals occurring near 

the airguns to avoid exposing them to 

sound pulses that might, at least in 

theory, cause hearing impairment. In 

addition, many cetaceans are likely to 

show some avoidance of the area with 

high received levels of airgun sound 

(see above). In those cases, the 

avoidance responses of the animals 

themselves will reduce or (most likely) 

avoid any possibility of hearing 

impairment. 

Non-auditory physical effects may 

also occur in marine mammals exposed 

to strong underwater pulsed sound. 

Possible types of non-auditory 

physiological effects or injuries that 

theoretically might occur in mammals 

close to a strong sound source include 

stress, neurological effects, bubble 

formation, resonance effects, and other 

types of organ or tissue damage. It is 

possible that some marine mammal 

species (i.e., beaked whales) may be 

especially susceptible to injury and/or 

stranding when exposed to strong 

pulsed sounds. However, as discussed 

below, there is no definitive evidence 

that any of these effects occur even for 

marine mammals in close proximity to 

large arrays of airguns. It is especially 

unlikely that any effects of these types 

would occur during the present project 

given the brief duration of exposure of 

any given mammal and the proposed 

monitoring and mitigation measures 

(see below). The following subsections 

discuss in somewhat more detail the 

possibilities of Temporary Threshold 

Shift (TTS), Permanent Threshold Shift 

(PTS), and non-auditory physical 

effects. 

Temporary Threshold Shift – TTS is 

the mildest form of hearing impairment 

that can occur during exposure to a 

strong sound (Kryter, 1985). While 

experiencing TTS, the hearing threshold 

rises and a sound must be stronger in 

order to be heard. At least in terrestrial 

mammals, TTS can last from minutes or 

hours to (in cases of strong TTS) days. 

For sound exposures at or somewhat 

above the TTS threshold, hearing 

sensitivity in both terrestrial and marine 

mammals recovers rapidly after 

exposure to the noise ends. Few data on 

sound levels and durations necessary to 

elicit mild TTS have been obtained for 

marine mammals, and none of the 

published data concern TTS elicited by 

exposure to multiple pulses of sound. 

Available data on TTS in marine 

mammals are summarized in Southall et 

al. (2007). 

For toothed whales exposed to single 

short pulses, the TTS threshold appears 

to be, to a first approximation, a 

function of the energy content of the 

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

Given the available data, the received 

level of a single seismic pulse (with no 

frequency weighting) might need to be 

approximately 186 dB re 1 μPa2.s (i.e., 

186 dB SEL or approximately 221–226 

dB pk-pk) in order to produce brief, 

mild TTS. Exposure to several strong 

seismic pulses that each have received 

levels near 175–180 dB SEL might result 

in slight TTS in a small odontocete, 

assuming the TTS threshold is (to a first 

approximation) a function of the total 

received pulse energy. The distance 

from the Langseth’s airguns at which the 

received energy level (per pulse) would 

be expected to be ≥175–180 dB SEL are 

the distances shown in the 190 dB re 1 

μPa (rms) column in Table 3 of L-DEO’s 

application and Table 1 above (given 

that the rms level is approximately 10–

15 dB higher than the SEL value for the 

same pulse). Seismic pulses with 

received energy levels ≥175–180 dB SEL 

(190 dB re 1 μPa (rms)) are expected to 

be restricted to radii no more than 140–

200 m (459–656 ft) around the airguns. 

The specific radius depends on the 

number of airguns, the depth of the 

water, and the tow depth of the airgun 

array. For an odontocete closer to the 

surface, the maximum radius with 

≥175–180 dB SEL or ≥190 dB re 1 μPa 

(rms) would be smaller. 

The above TTS information for 

odontocetes is derived from studies on 

the bottlenose dolphin and beluga. 

There is not published TTS information 

for other types of cetaceans. However, 

preliminary evidence from harbor 

porpoise exposed to airgun sound 

suggests that its TTS threshold may 

have been lower (Lucke et al. 2007). 

For baleen whales, there are no data, 

direct or indirect, on levels or properties 

of sound required to induce TTS. The 

frequencies to which baleen whales are 

most sensitive are lower than those for 

odontocetes, and natural background 

noise levels at those low frequencies 

tend to be higher. As a result, auditory 

thresholds of baleen whales within their 

frequency band of best hearing are 

believed to be higher (less sensitive) 

than are those of odontocetes at their 

best frequencies (Clark and Ellison, 

2004). From this, it is suspected that 

received levels causing TTS onset may 

also be higher in baleen whales. In any 

event, no cases of TTS are expected 

given three considerations: (1) the 

relatively low abundance of baleen 

whales expected in the planned study 

areas; (2) the strong likelihood that 

baleen whales would avoid the 

approaching airguns (or vessel) before 

being exposed to levels high enough for 

there to be any possibility of TTS; and 

(3) the mitigation measures that are 

planned. 

In pinnipeds, TTS thresholds 

associated with exposure to brief pulses 

(single or multiple) of underwater sound 

have not been measured. Initial 

evidence from prolonged (non-pulse) 

exposures suggested that some 

pinnipeds may incur TTS at somewhat 

lower received levels than do small 

odontocetes exposed for similar 

durations (Kastak et al., 1999, 2005; 

Ketten et al., 2001; Au et al., 2000). The 

TTS threshold for pulsed sounds has 

been indirectly estimated as being an 

SEL of approximately 171 dB re 1 μPa2.

s (Southall et al., 2007), which would be 

equivalent to a single pulse with 

received level approximately 181–186 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). 

A marine mammal within a radius of 

less than 100 m (328 ft) around a typical 


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large array of operating airguns might be 

exposed to a few seismic pulses with 

levels of greater than or equal to 205 dB, 

and possibly more pulses if the mammal 

moved with the seismic vessel. (As 

noted above, most cetacean species tend 

to avoid operating airguns, although not 

all individuals do so.) In addition, 

ramping up airgun arrays, which is 

standard operational protocol for large 

airgun arrays, should allow cetaceans to 

move away form the seismic source and 

to avoid being exposed to the full 

acoustic output of the airgun array. Even 

with a large airgun array, it is unlikely 

that the cetaceans would be exposed to 

airgun pulses at a sufficiently high level 

for a sufficiently long period to cause 

more than mild TTS, given the relative 

movement of the vessel and the marine 

mammal. The potential for TTS is much 

lower in this project. With a large array 

of airguns, TTS would be most likely in 

any odontocetes that bow-ride or 

otherwise linger near the airguns. While 

bow-riding, odontocetes would be at or 

above the surface, and thus not exposed 

to strong pulses given the pressurerelease effect at the surface. However, 

bow-riding animals generally dive 

below the surface intermittently. If they 

did so while bow-riding near airguns, 

they would be exposed to strong sound 

pulses, possibly repeatedly. If some 

cetaceans did incur TTS through 

exposure to airgun sounds, this would 

very likely be mild, temporary, and 

reversible. 

To avoid the potential for injury, 

NMFS has determined that cetaceans 

and pinnipeds should not be exposed to 

pulsed underwater noise at received 

levels exceeding, respectively, 180 and 

190 dB re 1 μPa (rms). As summarized 

above, data that are now available imply 

that TTS is unlikely to occur unless 

odontocetes (and probably mysticetes as 

well) are exposed to airgun pulses 

stronger than 180 dB re 1 μPa (rms). 

Permanent Threshold Shift – When 

PTS occurs, there is physical damage to 

the sound receptors in the ear. In some 

cases, there can be total or partial 

deafness, while in other cases, the 

animal has an impaired ability to hear 

sounds in specific frequency ranges. 

There is no specific evidence that 

exposure to pulses of airgun sound can 

cause PTS in any marine mammal, even 

with large arrays of airguns. However, 

given the possibility that mammals 

close to an airgun array might incur 

TTS, there has been further speculation 

about the possibility that some 

individuals occurring very close to 

airguns might incur PTS. Single or 

occasional occurrences of mild TTS are 

not indicative of permanent auditory 

damage in terrestrial mammals. 

Relationships between TTS and PTS 

thresholds have not been studied in 

marine mammals, but are assumed to be 

similar to those in humans and other 

terrestrial mammals. PTS might occur at 

a received sound level at least several 

decibels above that inducing mild TTS 

if the animal were exposed to strong 

sound pulses with rapid rise time (see 

Appendix B (f) of L-DEO’s application). 

The specific difference between the PTS 

and TTS thresholds has not been 

measured for marine mammals exposed 

to any sound type. However, based on 

data from terrestrial mammals, a 

precautionary assumption is that the 

PTS threshold for impulse sounds (such 

as airgun pulses as received close to the 

source) is at least 6 dB higher than the 

TTS threshold on a peak-pressure basis. 

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

estimated that received levels would 

need to exceed the TTS threshold by at 

least 15 dB for there to be risk of PTS. 

Thus, for cetaceans they estimate that 

the PTS threshold might be a 

cumulative SEL (for the sequence of 

received pulses) of approximately 198 

dB re 1 μPa2.s. Additional assumptions 

had to be made to derive a 

corresponding estimate for pinnipeds. 

Southall et al. (2007) estimate that the 

PTS threshold could be a cumulative 

SEL of approximately 186 dB 1 Pa2 s in 

the harbor seal; for the California sea 

lion and northern elephant seal the PTS 

threshold would probably be higher. 

Southall et al. (2007) also note that, 

regardless of the SEL, there is concern 

about the possibility of PTS if a cetacean 

or pinniped receives one or more pulses 

with peak pressure exceeding 230 or 

218 dB re 1 μPa (3.2 bar. m, 0–pk), 

which would only be found within a 

few meters of the largest (360–in3) 

airguns in the planned airgun array 

(Caldwell and Dragoset, 2000). A peak 

pressure of 218 dB re 1 μPa could be 

received somewhat farther away; to 

estimate that specific distance, one 

would need to apply a model that 

accurately calculates peak pressures in 

the near-field around an array of 

airguns. 

Given the higher level of sound 

necessary to cause PTS as compared 

with TTS, it is considerably less likely 

that PTS could occur. In fact, even the 

levels immediately adjacent to the 

airguns may not be sufficient to induce 

PTS, especially because a mammal 

would not be exposed to more than one 

strong pulse unless it swam 

immediately alongside the airgun for a 

period longer than the inter-pulse 

interval. Baleen whales generally avoid 

the immediate area around operating 

seismic vessels, as do some other 

marine mammals. The planned 

monitoring and mitigation measures, 

including visual monitoring, passive 

acoustic monitoring (PAM), power 

downs, and shut downs of the airguns 

when mammals are seen within the EZ 

will minimize the already minimal 

probability of exposure of marine 

mammals to sounds strong enough to 

induce PTS. 

Non-auditory Physiological Effects –

Non-auditory physiological effects or 

injuries that theoretically might occur in 

marine mammals exposed to strong 

underwater sound include stress, 

neurological effects, bubble formation, 

resonance effects, and other types of 

organ or tissue damage (Cox et al., 

2006.; Southall et al., 2007). However, 

studies examining such effects are 

limited. If any such effects do occur, 

they would probably be limited to 

unusual situations when animals might 

be exposed at close range for unusually 

long periods, when sound is strongly 

channeled with less-than-normal 

propagation loss, or when dispersal of 

the animals is constrained by 

shorelines, shallows, etc. Airgun pulses, 

because of their brevity and 

intermittence, are less likely to trigger 

resonance or bubble formation than are 

more prolonged sounds. It is doubtful 

that any single marine mammal would 

be exposed to strong seismic sounds for 

time periods long enough to induce 

physiological stress. 

Until recently, it was assumed that 

diving marine mammals are not subject 

to the bends or air embolism. This 

possibility was first explored at a 

workshop (Gentry [ed.], 2002) held to 

discuss whether a stranding of beaked 

whales in the Bahamas in 2000 

(Balcomb and Claridge, 2001; NOAA 

and USN, 2001) might have been related 

to bubble formation in tissues caused by 

exposure to noise from naval sonar. 

However, this link could not be 

confirmed. Jepson et al. (2003) first 

suggested a possible link between midfrequency sonar activity and acute 

chronic tissue damage that results from 

the formation in vivo of gas bubbles, 

based on a beaked whale stranding in 

the Canary Islands in 2002 during naval 

exercises. Fernandez et al. (2005a) 

showed those beaked whales did indeed 

have gas bubble-associated lesions, as 

well as fat embolisms. Fernandez et al. 

(2005b) also found evidence of fat 

embolism in three beaked whales that 

stranded 100 km (62 mi) north of the 

Canaries in 2004 during naval exercises. 

Examinations of several other stranded 

species have also revealed evidence of 

gas and fat embolisms (Arbelo et al., 

2005; Jepson et al., 2005a; Mendez et al., 

2005). Most of the afflicted species were 

deep divers. There is speculation that 


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gas and fat embolisms may occur if 

cetaceans ascend unusually quickly 

when exposed to aversive sounds, or if 

sound in the environment causes the 

destablization of existing bubble nuclei 

(Potter, 2004; Arbelo et al., 2005; 

Fernandez et al. 2005a; Jepson et al., 

2005b; Cox et al., 2006). Even if gas and 

fat embolisms can occur during 

exposure to mid-frequency sonar, there 

is no evidence that that type of effect 

occurs in response to airgun sounds. 

In general, little is known about the 

potential for seismic survey sounds to 

cause auditory impairment or other 

physical effects in marine mammals. 

Available data suggest that such effects, 

if they occur at all, would be limited to 

within short distances of the sound 

source and probably to projects 

involving large arrays of airguns. The 

available data do not allow for 

meaningful quantitative predictions of 

the numbers (if any) of marine mammals 

that might be affected in those ways. 

Marine mammals that show behavioral 

avoidance of seismic vessels, including 

most baleen whales, some odontocetes, 

and some pinnipeds, are especially 

unlikely to incur auditory impairment 

or non-auditory physical effects. It is not 

known whether aversive behavioral 

responses to airgun pulses by deepdiving species could lead to indirect 

physiological problems as apparently 

can occur upon exposure of some 

beaked whales to mid-frequency sonar 

(Cox et al., 2006). Also, the planned 

mitigation measures, including shut 

downs of the airguns, will reduce any 

such effects that might otherwise occur. 

Strandings and Mortality 

Marine mammals close to underwater 

detonations of high explosives can be 

killed or severely injured, and their 

auditory organs are especially 

susceptible to injury (Ketten et al., 1993; 

Ketten 1995). Airgun pulses are less 

energetic and have slower rise times, 

and there is no proof that they can cause 

injury, death, or stranding even in the 

case of large airgun arrays. However, the 

association of mass strandings of beaked 

whales with naval exercises and, in one 

case, an L-DEO seismic survey, has 

raised the possibility that beaked whales 

exposed to strong pulsed sounds may be 

especially susceptible to injury and/or 

behavioral reactions that can lead to 

stranding. Appendix B(g) of LDEO’s 

application provides addition details. 

Seismic pulses and mid-frequency 

sonar pulses are quite different. Sounds 

produced by airgun arrays are 

broadband with most of the energy 

below 1 kHz. Typical military midfrequency sonars operate at frequencies 

of 2–10 kHz, generally with a relatively 

narrow bandwidth at any one time. 

Thus, it is not appropriate to assume 

that there is a direct connection between 

the effects of military sonar and seismic 

surveys on marine mammals. However, 

evidence that sonar pulses can, in 

special circumstances, lead to physical 

damage and mortality (Balcomb and 

Claridge, 2001; NOAA and USN, 2001; 

Jepson et al., 2003; Fernandez et al., 

2004, 2005a; Cox et al., 2006), even if 

only indirectly, suggests that caution is 

warranted when dealing with exposure 

of marine mammals to any highintensity pulsed sound. 

There is no conclusive evidence of 

cetacean strandings as a result of 

exposure to seismic surveys. 

Speculation concerning a possible link 

between seismic surveys and strandings 

of humpback whales in Brazil (Engel et 

al., 2004) was not well founded based 

on available data (IAGC, 2004; IWC, 

2006). In September 2002, there was a 

stranding of two Cuvier’s beaked whales 

in the Gulf of California, Mexico, when 

the L-DEO vessel Ewing was operating a 

20–gun, 8,490–in3 array in the general 

area. The link between the stranding 

and the seismic survey was 

inconclusive and not based on any 

physical evidence (Hogarth, 2002; 

Yoder, 2002). Nonetheless, that plus the 

incidents involving beaked whale 

strandings near naval exercises 

involving use of mid-frequency sonar 

suggests a need for caution when 

conducting seismic surveys in areas 

occupied by beaked whales. No injuries 

of beaked whales are anticipated during 

the proposed study because of (1) the 

high likelihood that any beaked whales 

nearby would avoid the approaching 

vessel before being exposed to high 

sound levels, (2) the proposed 

monitoring and mitigation measures, 

and (3) differences between the sound 

sources operated by L-DEO and those 

involved in the naval exercises 

associated with strandings. 

Potential Effects of Other Acoustic 

Devices 

Multibeam Echosounder Signals 

The Simrad EM 120 12–kHz MBES 

will be operated from the source vessel 

at some times during the planned study. 

Sounds from the MBES are very short 

pulses, occurring for 15 ms once every 

5–20 s, depending on water depth. Most 

of the energy in the sound pulses 

emitted by the MBES is at frequencies 

centered at 12 kHz, and the maximum 

source level is 242 dB re 1 μPa (rms). 

The beam is narrow (1°) in fore-aft 

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

extent. Each ping consists of nine 

successive fan-shaped transmissions 

(segments) at different cross-track 

angles. Any given mammal at depth 

near the trackline would be in the main 

beam for only one or two of the nine 

segments. Also, marine mammals that 

encounter the MBES are unlikely to be 

subjected to repeated pulses because of 

the narrow fore-aft width of the beam 

and will receive only limited amounts 

of pulse energy because of the short 

pulses. Animals close to the ship (where 

the beam is narrowest) are especially 

unlikely to be ensonified for more than 

one 2–15 ms pulse (or two pulses if in 

the overlap area). Similarly, Kremser et 

al. (2005) noted that the probability of 

a cetacean swimming through the area 

of exposure when an MBES emits a 

pulse is small. The animal would have 

to pass the transducer at close range and 

be swimming at speeds similar to the 

vessel in order in order to receive the 

multiple pulses that might result in 

sufficient exposure to cause TTS. 

Burkhardt et al. (2007) concluded that 

immediate direct auditory injury was 

possible only if a cetacean dived under 

the vessel into the immediate vicinity of 

the transducer. 

Navy sonars that have been linked to 

avoidance reactions and stranding of 

cetaceans (1) generally have a longer 

pulse duration that the Simrad EM120, 

and (2) are often directed close to 

horizontally vs. more downward for the 

MBES.. The area of possible influence of 

the MBES is much smaller a narrow 

band below the source vessel. The 

duration of exposure for a given marine 

mammal can be much longer for a Navy 

sonar. 

Marine mammal communications will 

not be masked appreciably by the MBES 

signals given its low duty cycle and the 

brief period when an individual 

mammal is likely to be within its beam. 

Furthermore, in the case of baleen 

whales, the signals (12 kHz) do not 

overlap with the predominant 

frequencies in the calls, which would 

avoid significant masking. 

Behavioral reactions of free-ranging 

marine mammals to sonars and other 

sound sources appear to vary by species 

and circumstance. Observed reactions 

have included silencing and dispersal 

by sperm whales (Watkins et al., 1985), 

increased vocalizations and no dispersal 

by pilot whales (Rendell and Gordon, 

1999), and the previously-mentioned 

beachings by beaked whales. During 

exposure to a 21–25 kHz whale-finding 

sonar with a source level of 215 dB re 

1 μPa, gray whales showed slight 

avoidance (approximately 200 m; 656 ft) 

behavior (Frankel, 2005). However, all 

of those observations are of limited 

relevance to the present situation. Pulse 

durations from those sonars were much 


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longer than those of the MBES, and a 

given mammal would have received 

many pulses from the naval sonars. 

During L-DEO’s operations, the 

individual pulses will be very short, and 

a given mammal would not receive 

many of the downward-directed pulses 

as the vessel passes by. 

Captive bottlenose dolphins and a 

white whale exhibited changes in 

behavior when exposed to 1 s pulsed 

sounds at frequencies similar to those 

that will be emitted by the MBES used 

by L-DEO and to shorter broadband 

pulsed signals. Behavioral changes 

typically involved what appeared to be 

deliberate attempts to avoid the sound 

exposure (Schlundt et al., 2000; 

Finneran et al., 2002; Finneran and 

Schlundt, 2004). The relevance of those 

data to free-ranging odontocetes is 

uncertain, and in any case, the test 

sounds were quite different in either 

duration or bandwidth as compared 

with those from an MBES. 

L-DEO is not aware of any data on the 

reactions of pinnipeds to sonar or 

echosounder sounds at frequencies 

similar to the 12 kHz frequency of the 

Langseth’s MBES. Based on observed 

pinniped responses to other types of 

pulsed sounds, and the likely brevity of 

exposure to the MBES sounds, pinniped 

reactions are expected to be limited to 

startle or otherwise brief responses of no 

lasting consequence to the animals. 

NMFS believes that the brief exposure 

of marine mammals to one pulse, or 

small numbers of signals, from the 

MBES are not likely to result in the 

harassment of marine mammals. 

Sub-bottom Profiler Signals 

A SBP will be operated from the 

source vessel during the planned study. 

Sounds from the SBP are very short 

pulses, occurring for 1–4 ms once every 

second. Most of the energy in the sound 

pulses emitted by the SBP is at mid 

frequencies, centered at 3.5 kHz. The 

beamwidth is approximately 30° and is 

directed downward. The SBP on the 

Langseth has a maximum source level of 

204 dB re 1 μPam. Kremser et al. (2005) 

noted that the probability of a cetacean 

swimming through the area of exposure 

when a bottom profiler emits a pulse is 

small, and if the animal was in the area, 

it would have to pass the transducer at 

close range in order to be subjected to 

sound levels that could cause TTS. 

Marine mammal communications will 

not be masked appreciably by the SBP 

signals given their directionality and the 

brief period when an individual 

mammal is likely to be within its beam. 

Furthermore, in the case of most 

odontocetes, the signals do not overlap 

with the predominant frequencies in the 

calls, which would avoid significant 

masking. 

Marine mammal behavioral reactions 

to other pulsed sound sources are 

discussed above, and responses to the 

SBP are likely to be similar to those for 

other pulsed sources if received at the 

same levels. The pulsed signals from the 

SBP are somewhat weaker than those 

from the MBES. Therefore, behavioral 

responses are not expected unless 

marine mammals are very close to the 

source. 

It is unlikely that the SBP produces 

pulse levels strong enough to cause 

hearing impairment or other physical 

injuries even in an animal that is 

(briefly) in a position near the source. 

The SBP is usually operated 

simultaneously with other higher-power 

acoustic sources. Many marine 

mammals will move away in response 

to the approaching higher-power 

sources or the vessel itself before the 

mammals would be close enough for 

there to be any possibility of effects 

from the less intense sounds from the 

SBP. In the case of mammals that do not 

avoid the approaching vessel and its 

various sound sources, mitigation 

measures that would be applied to 

minimize effects of other sources would 

further reduce or eliminate any minor 

effects of the SBP. 

NMFS believes that to avoid the 

potential for permanent physiological 

damage (Level A Harassment), cetaceans 

and pinnipeds should not be exposed to 

pulsed underwater noise at received 

levels exceeding, respectively, 180 and 

190 dB re 1 μPa (rms). The 

precautionary nature of these criteria is 

discussed in Appendix B (f) of L-DEO’s 

application, including the fact that the 

minimum sound level necessary to 

cause permanent hearing impairment is 

higher, by a variable and generally 

unknown amount, than the level that 

induces barely-detectable temporary 

threshold shift (TTS) and the level 

associated with the onset of TTS is often 

considered to be a level below which 

there is no danger of permanent damage. 

NMFS also assumes that cetaceans or 

pinnipeds exposed to levels exceeding 

160 dB re 1 μPa (rms) may experience 

Level B Harassment. 

Estimated Take by Incidental 

Harassment 

All anticipated takes would be ‘‘takes 

by harassment’’, involving temporary 

changes in behavior. The proposed 

mitigation measures are expected to 

minimize the possibility of injurious 

takes. The sections below describe 

methods to estimate ‘‘take by 

harassment’’, and present estimates of 

the numbers of marine mammals that 

might be affected during the proposed 

Gulf of Alaska seismic survey. The 

estimates of ‘‘take by harassment’’ are 

based on consideration of the number of 

marine mammals that are exposed to 

certain received sound levels by 

approximately 2,386 km of seismic 

surveys in the Gulf of Alaska. The main 

sources of distributional and numerical 

data used in deriving the estimates are 

described below. 

Empirical data concerning 

190-, 180-, 170-, and 160 dB re 1 μPa 

isopleth distances in deep and shallow 

water were acquired for various airgun 

configurations during the acoustic 

calibration study of the R/V Maurice 

Ewing’s (Ewing) 20–airgun 8,600 in3

array in 2003 (Tolstoy et al., 2004a,b). 

The results showed that radii around 

the airguns where the received level was 

180 dB re 1 μPa rms, the threshold for 

estimating level B harassment 

applicable to cetaceans (NMFS 2000), 

varied with water depth. Similar depthrelated variation is likely for the 190–dB 

re 1 μPa threshold for estimating Level 

B harassment applicable to cetaceans 

and the 190–dB re 1 μPa threshold 

applicable to pinnipeds, although these 

were not measured. The L-DEO model 

does not allow for bottom interactions, 

and thus is most directly applicable to 

deep water and to relatively short 

ranges. 

The empirical data indicated that, for 

deep water (≤1,000 m; 3,280 ft), the LDEO model (as applied to the Ewing’s 

airgun configurations) overestimated the 

measured received sound levels at a 

given distance (Tolstoy et al., 2004a,b). 

However, to be conservative, the 

distances predicted by L-DEO’s model 

for the survey will be applied to deepwater areas during the proposed study 

(see Figure 3 and 4 and Table 1 in the 

application). As very few, if any, 

mammals are expected to occur deeper 

than 2,000 m (6,562 ft), this depth was 

used as the maximum relevant depth. 

Empirical measurements of sounds 

from the Ewing’s airgun arrays were not 

conducted for intermediate depths 

(100–1,000 m; 328–3,280 ft). On the 

expectation that results would be 

intermediate, the estimates provided by 

the model for deep-water situations are 

used to obtain estimates for 

intermediate-depth sites. Corresponding 

correction factors, applied to the 

modeled radii for the Langseth’s airgun 

configuration, will be used during the 

proposed study for intermediate depths 

(see Table 1 of the application). 

Empirical measurements near the 

Ewing indicated that in shallow water 

(<100 m; 328 ft), the L-DEO model 

underestimates actual levels. In 

previous L-DEO projects, the exlusion 


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zones were typically based on measured 

values and ranged from 1.3 to 15x 

higher than the modeled values 

depending on the size of the airgun 

array and the sound level measured 

(Tolstoy et al., 2004b). During the 

proposed cruise, similar correction 

factors will be applied to derive 

appropriate shallow-water radii from 

the modeled deep-water radii for the 

Langseth’s airgun configuration (see 

Table 1 of the application). 

Using the modeled distances and 

various correction factors, Table 1 (from 

the application) shows the distances at 

which four rms sound levels are 

expected to be received from the 36–

airgun array and a single airgun in three 

different water depths. 

The anticipated radii of influence of 

the MBES and the SBP are much smaller 

than those for the airgun array. It is 

assumed that, during simultaneous 

operations of the airgun array and 

echosounders, marine mammals close 

enough to be affected by the 

echosounders would already be affected 

by the airguns. However, whether or not 

the airguns are operating 

simultaneously with the echosounders, 

marine mammals are not expected to be 

exposed to sound pressure levels great 

enough or long enough for taking to 

occur given echosounders’

characteristics (e.g., narrow downwarddirected beam) and other considerations 

described above. Therefore, no 

additional allowance is included for 

animals that might be affected by sound 

sources other than airguns. 

There are few systematic data on the 

numbers and distributions of marine 

mammals in SE Alaska and the GOA. 

Zerbini et al. (2003, 2006, 2007) 

conducted vessel-based surveys in the 

northern and western GOA from the 

Kenai Peninsula to the central Aleutian 

Islands during July-August 2001–2003. 

Killer whales were the principal target 

of the surveys, but the abundance and 

distribution of fin, humpback, and 

minke whales were also reported. Waite 

(2003) conducted vessel-based surveys 

in the northern and western GOA from 

PWS to approximately 160° W off 

Alaska Peninsula during 26 June- 15 

July 2003; cetaceans recorded included 

small odontocetes, beaked whales, and 

mysticetes. The eastern part of Zerbini 

et al.’s surveys and Waite’s survey were 

confined to water <1,000 m deep, and 

most effort was in depths <100 m. 

Dahlheim et al. (2000) conducted aerial 

surveys of the nearshore waters from 

Bristol Bay to Dixon Entrance for harbor 

porpoises; SE Alaska was surveyed 

during 1–26 June 1993. Dahlheim and 

Towell (1994) conducted vessel-based 

surveys of Pacific white-sided dolphins 

in the inland waterways of SE Alaska 

during April-May, June or July, and 

September- early October of 1991–1993. 

In a report on a seismic cruise in SE 

Alaska from Dixon Entrance to Kodiak 

Island during August-September 2004, 

MacLean and Koski (2005) included 

density estimates of cetaceans and 

pinnipeds for each of three depth ranges 

(<100 m, 100–1,000 m, and >1,000 m) 

during non-seismic periods. 

Most surveys for pinnipeds in 

Alaskan waters have estimated the 

number of animals at haul-out sites, not 

in the water (e.g., Loughlin, 1994; Sease 

et al., 2001; Withrow and Cesarone, 

2002; Sease and York, 2003). To our 

knowledge, the estimates of MacLean 

and Koski (2005) are the only in-water 

estimates of pinnipeds in the proposed 

survey area. 

Table 7 in L-DEO’s application gives 

the average and maximum densities in 

each of three depth ranges for each 

cetacean and pinniped species reported 

to occur in SE Alaska. The densities 

from MacLean and Koski (2005) and 

those calculated from effort and 

sightings in Dahlheim and Towell 

(1994) and Waite (2003) have been 

corrected for both detectability and 

availability bias using correction factors 

from Dahlheim et al. (2000) and Koski 

et al. (1998). Detectability bias is 

associated with diminishing sightability 

with increasing lateral distance from the 

trackline. Availability bias refers to the 

fact that there is less-than–100 percent 

probability of sighting an animal that is 

present along the survey trackline. In 

determining the estimated numbers, LDEO used the killer whale and 

mysticete densities from the 

easternmost blocks (1–6) surveyed by 

Zerbini et al. (2006, 2007), the harbor 

porpoise densities for the SE Alska 

portion of the areas surveyed by 

Dahlheim et al. (2000), and only the 

Pacific white-sided dolphin data from 

the June or July and September– early 

October surveys by Dahlheim and 

Towell (1994). Maps of effort and 

sightings in Waite (2003) an Zerbini et 

al. (2006, 2007) were used to roughly 

allocate effort and sighting between 

waters <100 m and 100–1,000 m deep 

as either all or none, most (80 percent), 

or similar (50 percent). 

There is some uncertainty about the 

representatives of the data and the 

assumptions used in the calculations 

below for three main reasons: (1) all but 

the MacLean and Koski (2005) and 

Dahlheim and Towell (1994) Septemberearly October surveys were carried out 

earlier (June-July) than the proposed 

September survey; (2) the Waite (2003) 

and Zerbini et al. (20006, 2007) surveys 

were in the northern and western GOA; 

and (3) only the MacLean and Koski 

(2005) surveys included depths >1,000 

m, whereas approximately 43 percent of 

the proposed line-km are in water 

depths >1,000 m. However, these 

represent the best available information. 

Also, to provide some allowance for 

these uncertainties L-DEO calculated, 

‘‘maximum estimates’’ as well as ‘‘best 

estimates’’ of the densities present and 

numbers potentially affected. Best 

estimates of density are effort-weighted 

mean densities from all previous 

surveys, whereas maximum estimates of 

density come from whichever of the 

individual surveys provided the highest 

density. Where only one estimate was 

available, the maximum density was 

assumed to be the observed (best) 

density multiplied by 1.5. 

For three species, L-DEO’s density 

estimates are much higher than 

densities expected during the proposed 

survey. The estimates for humpback and 

fin whales are based on surveys where 

large concentrations were sighted in 

nearshore waters and often inland 

waterways, viz. Sitka Sound, Icy Strait, 

and the bottom of Lynn Canal (MacLean 

and Koski, 2005), and near Kodiak 

Island (Waite, 2003; Zerbini et al., 

2006). No such concentrations are 

expected in the proposed survey area. LDEO’s estimates for Dall’s porpoise are 

from vessel-based surveys without 

seismic survey 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 to approach the vessel. 

Dall’s porpoises are tolerant of small 

airgun sources (MacLean and Koski, 

2005) and tolerated higher noise levels 

than other species during a large array 

survey (Bain and Williams, 2006), but 

they did respond to that and another 

large airgun array by moving away 

(Calambokidis and Osmek, 1998; Bain 

and Williams, 2006). Because of these 

considerable overestimates, the best and 

maximum estimates in Table 7 of LDEO’s application were halved by LDEO to calculate numbers exposed. In 

fact, actual densities are undoubtedly 

much lower than that. 

The estimated numbers of individuals 

potentially exposed are presented below 

based on a 160–dB re 1 μPa (rms) Level 

B harassment exposure threshold for 

cetaceans and pinnipeds. It is assumed 

that marine mammals exposed to airgun 

sounds at these levels might experience 

disruption of behavioral patterns. 

It should be noted that the following 

estimates of takes by harassment assume 

that the surveys will be fully completed; 


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in fact, the planned number of line-km 

has been increased by 25 percent to 

accomodate 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 linekm to seismic operations that can be 

undertaken. Furthermore, any marine 

mammal sightings within or near the 

designated EZ (see will result in the 

shut down of seismic operations. Thus, 

the following estimates of the numbers 

of marine mammals exposed to 160–dB 

sounds probably overestimate the actual 

numbers of marine mammals that might 

be involved. These estimates assume 

that there will be no weather, 

equipment, or mitigation delays, which 

is highly unlikely. 

The number of different individuals 

that may be exposed to airgun sounds 

with received levels ≥160 dB re 1 μPa 

(rms) on one or more occasions was 

estimated by considering the total 

marine area that would be within the 

160–dB radius around the operating 

airgun array on at least one occasion. 

The proposed seismic lines do not run 

parallel to each other in close proximity, 

which minimizes the number of times 

an individual mammal may be exposed 

during the survey. Only one transect 

line is proposed to be surveyed twice, 

and it is unknown how much time will 

pass between the first and the second 

transit. Therefore, some of the same 

individuals may be approached by the 

operating airguns and come within the 

160–dB distance on up to two 

occasions. However, this also means 

that some different marine mammals 

could occur in the area during the 

second pass. The line that could be 

surveyed twice was counted twice in LDEO’s calculations. 

For each depth stratum, the number of 

different individuals potentially 

exposed to received levels ≥160 dB re 1 

μPa (rms) was calculated by 

multiplying: 

• The expected species density, either 

‘‘mean’’ (i.e., best estimate) or 

‘‘maximum’’, for a particular water 

depth, times 

• The anticipated minimum area to 

be ensonified to that level during airgun 

operations in each water depth stratum. 

The same approach was used to 

estimate exposures of pinnipeds, 

delphinids, and Dall’s porpoise to 

received levels ≥170 dB. 

The area expected to be ensonified 

was determined by entering the planned 

survey lines into a MapInfo Geographic 

Information System (GIS), using the GIS 

to identify the relevant areas by 

‘‘drawing’’ the applicable 160–dB buffer 

around each seismic line (depending on 

water and tow depth) and then 

calculating the total area within the 

buffers. Areas where overlap occurred 

(because of intersecting lines) were 

limited and included only once to 

determine the area expected to be 

ensonified. 

Applying the approach described 

above, approximately 28,900 km2 

would be within the 160–dB isopleth on 

one or more occasions during the 

survey, including the 25 percent added 

as a contingency. However, this 

approach does not allow for turnover in 

the mammal populations in the study 

area during the course of the study. This 

might somewhat underestimate actual 

numbers of individuals exposed, 

although the conservative (i.e., probably 

overestimated) line-kilometer distances 

used to calculate the area may offset 

this. In addition, the approach assumes 

that no cetaceans will move away or 

toward the trackline (as the Langseth 

approaches) in response to increasing 

sound levels prior to the time the levels 

reach 160 dB re 1 μPa (rms). Another 

way of interpreting the estimates that 

follow is that they represent the number 

of individuals that are expected (in the 

absence of the seismic activity) to occur 

in the waters that will be exposed to 

≥160 dB re 1 μPa (rms). 

TABLE 3. ESTIMATES OF THE POSSIBLE NUMBERS OF MARINE MAMMALS EXPOSED TO SOUND LEVELS ≥160 DB DURING L 

DEO’S PROPOSED SEISMIC SURVEY IN SE ALASKA IN SEPTEMBER 2008. THE PROPOSED SOUND SOURCE CONSISTS

OF A 36-GUN, 6600-IN3, AIRGUN ARRAY. RECEIVED LEVELS OF AIRGUN SOUNDS ARE EXPRESSED IN DB RE 1 μPARMS

(AVERAGED OVER PULSE DURATION), CONSISTENT WITH NMFS’ PRACTICE. NOT ALL MARINE MAMMALS WILL CHANGE

THEIR BEHAVIOR WHEN EXPOSED TO THESE SOUND LEVELS, BUT SOME MAY ALTER THEIR BEHAVIOR WHEN LEVELS ARE

LOWER (SEE TEXT). THE COLUMN OF NUMBERS IN BOLDFACE SHOWS THE NUMBERS OF ′′TAKES′′ FOR WHICH AUTHORIZATION IS REQUESTED. 

Species 

Number of Individuals Exposed to Sound Levels >160 dB 

Requested 

Take 

Authorization 

Best Estimate 1

Maximum Estimate 1

Number % of 

Pop’n 2

<100 m 100-1000 m >1000 m Total <100 m 100-1000 m >1000 m Total 

Odontocetes 

Sperm whale 0 4 45 49 0.2 0 7 67 74 74 

Cuvier’s beaked 

whale 

0 35 0 35 0.3 0 47 0 47 47 

Baird’s beaked 

whale 

0 8 0 8 0.1 0 11 0 11 11 

Stejneger’s 

beaked whale 

0 0 0 0 0 0 0 0 3 3 

Beluga 0 0 0 0 0 0 0 0 5 5 

Pacific white-sided 

dolphin 

13 43 0 56 0.1 27 176 0 203 203 

Risso’s dolphin 0 0 0 0 0 0 0 0 5 5 

Killer whale 65 51 0 116 1.4 173 112 0 285 285 


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45420 Federal Register / Vol. 73, No. 151 / Tuesday, August 5, 2008 / Notices 

TABLE 3. ESTIMATES OF THE POSSIBLE NUMBERS OF MARINE MAMMALS EXPOSED TO SOUND LEVELS ≥160 DB DURING L 

DEO’S PROPOSED SEISMIC SURVEY IN SE ALASKA IN SEPTEMBER 2008. THE PROPOSED SOUND SOURCE CONSISTS

OF A 36-GUN, 6600-IN3, AIRGUN ARRAY. RECEIVED LEVELS OF AIRGUN SOUNDS ARE EXPRESSED IN DB RE 1 μPARMS

(AVERAGED OVER PULSE DURATION), CONSISTENT WITH NMFS’ PRACTICE. NOT ALL MARINE MAMMALS WILL CHANGE

THEIR BEHAVIOR WHEN EXPOSED TO THESE SOUND LEVELS, BUT SOME MAY ALTER THEIR BEHAVIOR WHEN LEVELS ARE

LOWER (SEE TEXT). THE COLUMN OF NUMBERS IN BOLDFACE SHOWS THE NUMBERS OF ′′TAKES′′ FOR WHICH AUTHORIZATION IS REQUESTED.—Continued 

Species 

Number of Individuals Exposed to Sound Levels >160 dB 

Requested 

Take 

Authorization 

Best Estimate 1

Maximum Estimate 1

Number % of 

Pop’n 2

<100 m 100-1000 m >1000 m Total <100 m 100-1000 m >1000 m Total 

Short-finned pilot 

whale 

0 0 0 0 0 0 0 0 20 20 

Harbor porpoise 118 228 0 346 0.4 239 309 0 548 548 

Dall’s porpoise 372 4225 783 5379 0.5 561 5594 1174 7329 7329 

Mysticetes 

North Pacific right 

whale 

0 0 0 0 0 0 0 0 2 2 

Gray whale 0 0 0 0 0 0 0 0 6 6 

Humpback whale 83 76 87 246 4.1 138 156 130 424 424 

Minke whale 6 3 0 9 0.1 25 16 0 41 41 

Fin whale 19 71 0 89 0.6 49 129 0 178 178 

Blue whale 0 0 0 0 0 0 0 0 2 2 

Pinnipeds 

Northern fur seal 0 0 0 0 0 0 0 0 5 5 

Harbor seal 10 259 0 269 <0.1 15 388 0 403 403 

Steller sea lion 20 54 0 74 <0.1 30 80 0 110 110 

1 Best and maximum estimates of density are from Table 3 in L-DEO’s application. 2 Regional population size estimates are from Table 2 of L-DEO’s application. 

The ‘‘best estimates’’ of the numbers 

of individual marine mammals that 

could be exposed to seismic sounds 

with received levels ≥160 dB re 1 μPa 

(rms) during the proposed survey is 

shown in Table 8 of L-DEO’s application 

and Table 3 (shown above). That total 

includes 49 sperm, 246 humpback, and 

89 fin whales, which would represent 

0.2 percent, 4.1 percent, and 0.6 

percent, respectively, of the regional 

populations (Table 3). However the 

numbers of humpback and fin whales 

exposed are overestimated considerably 

because the estimated densities are 

overestimates (see previous section). 

Dall’s porpoise is expected to be the 

most common species in the study area; 

the best estimate of the number of Dall’s 

porpoise that could be exposed is 5,379 

or 0.5 percent of the regional population 

(Table 3). This is also an overestimate 

because the estimated densities are 

overestimates (see previous section). 

Estimates for other species are lower 

(Table 3). 

The ‘‘maximum estimate’’ column in 

Table 3 shows estimates totaling 9,701 

marine mammals for the three depth 

ranges combined. For species that could 

occur in the study area but were not 

sighted in the surveys from which 

density estimates were calculated, the 

average group size has been used as the 

maximum estimate. 

Based on the ‘‘best’’ densities, 74 

threatened Steller sea lions and 269 

harbor seals could be exposed to airgun 

sounds ≥160 dB re 1 μPa (rms), which 

would represent <0.1 percent for both of 

the respective regional populations. The 

‘‘maximum estimate’’ column in Table 3 

shows an estimated 110 Steller sea lions 

could be exposed to airgun sounds ≥160 

dB re 1 μPa (rms). The corresponding 

numbers for harbor seals are 403. LDEO 

has also included a low maximum 

estimate for the northern fur seal, a 

species that could be present, but whose 

density was not calculated because it 

was not sighted during the survey of 

MacLean and Koski (2005). The 

numbers for which ‘‘take authorization’’

is requested, given in the far right 

column of Table 3, are based on the 

maximum 160–dB estimates. 

Potential Effects on Habitat 

The proposed L-DEO seismic survey 

in the GOA will not result in any 

permanent impact on habitats used by 

marine mammals or to the food sources 

they use. The main impact issue 

associated with the proposed activity 

will be temporarily elevated noise levels 

and the associated direct effects on 

marine mammals, as discussed above. 

The following sections briefly review 

effects of airguns on fish and 

invertebrates, and more details are 

included in Appendices C and D, 

respectively, in L-DEO’s application. 

Effects on Fish 

One reason for the adoption of airguns 

as the standard energy source for marine 

seismic surveys was that, unlike 

explosives, they have not been 

associated with large-scale fish kills. 

However, existing information relating 

to the impacts of seismic surveys on 


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marine fish populations and 

invertebrate species is very limited (see 

Appendix C of L-DEO’s application). 

There are three types of potential effects 

of exposure to seismic surveys: (1) 

pathological, (2) physiological, and (3) 

behavioral. Pathological effects include 

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 the ultimate pathological effect 

on individual animals (i.e., mortality). 

The specific received sound levels at 

which permanent adverse effects to fish 

potentially 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. Thus, available 

information provides limited insight on 

possible real-world effects at the ocean 

or population scale. This makes drawing 

conclusions about impacts on fish 

problematic because ultimately, the 

most important aspect of potential 

impacts relates to how exposure to 

seismic survey sound affects marine fish 

populations and their viability, 

including their availability to fisheries. 

The following sections provide a 

general synopsis of available 

information on the effects of exposure to 

seismic and other anthropogenic sound 

as relevant to fish and invertebrates. The 

information comprises results from 

scientific studies of varying degrees of 

soundness and some anecdotal 

information. Some of the data sources 

may have serious shortcomings in 

methods, analysis, interpretation, and 

reproducibility that must be considered 

when interpreting their results (see 

Hastings and Popper, 2005). Potential 

adverse effects of the program’s sound 

sources on marine fish are then noted. 

Pathological Effects – The potential 

for pathological damage to hearing 

structures in fish depends on the energy 

level of the received sound and the 

physiology and hearing capability of the 

species in question (see Appendix C of 

L-DEO’s application). For a given sound 

to result in hearing loss, the sound must 

exceed, by some specific amount, the 

hearing threshold of the fish for that 

sound (Popper, 2005). The 

consequences of temporary or 

permanent hearing loss in individual 

fish on a fish population is unknown; 

however, it likely depends on the 

number of individuals affected and 

whether critical behaviors involving 

sound (e.g., predator avoidance, prey 

capture, orientation and navigation, 

reproduction, etc.) are adversely 

affected. 

Little is known about the mechanisms 

and characteristics of damage to fish 

that may be inflicted by exposure to 

seismic survey sounds. Few data have 

been presented in the peer-reviewed 

scientific literature. As far as is known, 

there are two valid papers with proper 

experimental methods, controls, and 

careful pathological investigation 

implicating sounds produced by actual 

seismic survey airguns with adverse 

anatomical effects. One such study 

indicated anatomical damage and the 

second indicated TTS in fish hearing. 

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 fishes from the 

Mackenzie River Delta. This study 

found that broad whitefish (Coreogonus 

nasus) that received a sound exposure 

level of 177 dB re 1 μPa2.s showed no 

hearing loss. During both studies, the 

repetitive exposure to sound was greater 

than would have occurred during a 

typical seismic survey. However, the 

substantial low-frequency energy 

produced by the airgun arrays [less than 

approximately 400 Hz in the study by 

McCauley et al. (2003) and less than 

approximately 200 Hz in Popper et al. 

(2005)] likely did not propagate to the 

fish because the water in the study areas 

was very shallow (approximately 9 m, 

29.5 ft, in the former case and <2 m, 6.6 

ft, in the latter). Water depth sets a 

lower limit on the lowest sound 

frequency that will propagate (the ‘‘cutoff frequency’’) at about one-quarter 

wavelength (Urick, 1983; Rogers and 

Cox, 1988). 

In water, acute injury and death of 

organisms exposed to seismic energy 

depends primarily on two features of 

the sound source: (1) the received peak 

pressure, and (2) the time required for 

the pressure to rise and decay (Hubbs 

and Rechnitzer, 1951; Wardle et al., 

2001). Generally, the higher the received 

pressure and the less time it takes for 

the pressure to rise and decay, the 

greater the chance of acute pathological 

effects. Considering the peak pressure 

and rise/decay time characteristics of 

seismic airgun arrays used today, the 

pathological zone for fish and 

invertebrates would be expected to be 

within a few meters of the seismic 

source (Buchanan et al., 2002). 

Numerous other studies provide 

examples of no fish mortality upon 

exposure to seismic sources (Falk and 

Lawrence, 1973; Holliday et al., 1987; 

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

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

Bjarti, 2002; Hassel et al., 2003; Popper 

et al., 2005). 

Except for these two studies, at least 

with airgun-generated sound treatments, 

most contributions rely on rather 

subjective assays such as fish ‘‘alarm’’ or 

‘‘startle response’’ or changes in catch 

rates by fishers. These observations are 

important in that they attempt to use the 

levels of exposures that are likely to be 

encountered by most free-ranging fish in 

actual survey areas. However, the 

associated sound stimuli are often 

poorly described, and the biological 

assays are varied (Hastings and Popper, 

2005). 

Wardle et al. (2001) suggested that in 

water, acute injury and death of 

organisms exposed to seismic energy 

depends primarily on two features of 

the sound source: (1) the received peak 

pressure and (2) the time required for 

the pressure to rise and decay. 

Generally, as received pressure 

increases, the period for 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 fih 

would be expected to be with a few 

meters of the seismic source. Numerous 

other studies provide examples of no 

fish mortality upon exposure to seismic 

sources (Falk and Lawrence 1973; 

Holliday et al., 1987; La Bella et al., 

1996; Santulli et al., 1999; McCauley et 

al., 2000a,b, 2003; Bjarti, 2002; Hassel et 

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

Some studies have reported that 

mortality of fish, fish eggs, or larvae can 

occur close to seismic sources 

(Kostyuchenko, 1973; Dalen and 

Knutsen, 1986; Booman et al., 1996; 

Dalen et al., 1996). Some of the reports 

claimed seismic effects from treatments 

quite different from actual seismic 

survey sounds or even reasonable 

surrogates. Saetre and Ona (1996) 

applied a ‘‘worst-case scenario’’

mathematical model to investigate the 

effects of seismic energy on fish eggs 

and larvae and concluded that mortality 

rates caused by exposure to seismic are 

so low, as compared to natural mortality 


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rates, that the impact of seismic 

surveying on recruitment to a fish stock 

must be regarded as insignificant. 

Some studies have suggested that 

seismic survey sound has a limited 

pathological impact on early 

developmental stages of crustaceans 

(Pearson et al., 1994; Christian et al., 

2003; DFO, 2004). However, the impacts 

appear to be either temporary or 

insignificant compared to what occurs 

under natural conditions. Controlled 

field experiments on adult crustaceans 

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

and adult cephalopods (McCauley et al., 

2000a,b) exposed to seismic survey 

sound have not resulted in any 

significant pathological impacts on the 

animals. It has been suggested that 

exposure to commercial seismic survey 

activities has injured giant squid 

(Guerra et al., 2004), but there is no 

evidence to support such claims. 

Physiological Effects – Physiological 

effects refer to cellular and/or 

biochemical responses of fish and 

invertebrates to acoustic stress. Such 

stress potentially could affect fish and 

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 or fish after exposure to 

seismic survey sound appear to be 

temporary (hours to days) in all studies 

done to date (see Payne et al., 2007 for 

invertebrates; see Sverdrup et al., 1994; 

McCauley et al., 2000a,b for fish). 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 (see Appendix C of L-DEO’s 

application). 

Summary of Physical (Pathological 

and Physiological) Effects – As 

indicated in the preceding general 

discussion, there is a relative lack of 

knowledge about the potential physical 

(pathological and physiological) effects 

of seismic energy on marine fish and 

invertebrates. Available data suggest 

that there may be physical impacts on 

egg, larval, juvenile, and adult stages at 

very close range. Considering typical 

source levels associated with 

commercial seismic arrays, close 

proximity to the source would result in 

exposure to very high energy levels. 

Whereas egg and larval stages are not 

able to escape such exposures, juveniles 

and adults most likely would avoid it. 

In the case of eggs and larvae, it is likely 

that the numbers adversely affected by 

such exposure would not be that 

different from those succumbing to 

natural mortality. Limited data 

regarding physiological impacts on fish 

and invertebrates indicate that these 

impacts are short term and are most 

apparent after exposure at close range. 

The proposed seismic program for 

2008 is predicted to have negligible to 

low physical effects on the various life 

stages of fish and invertebrates for its 

short duration (approximately 24 days) 

and approximately 1,909–km of unique 

survey lines extent. Therefore, physical 

effects of the proposed program on fish 

and invertebrates would not be 

significant. 

Behavioral Effects – Because of the 

apparent lack of serious pathological 

and physiological effects of seismic 

energy on marine fish and invertebrates, 

the highest level of concern now centers 

on the possible effects of exposure to 

seismic surveys on the distribution, 

migration patterns, mating, and 

catchability of fish. There is a need for 

more information on exactly what 

effects such sound sources might have 

on the detailed behavior patterns of fish 

and invertebrates at different ranges. 

Behavioral effects include changes in 

the distribution, migration, mating, and 

catchability of fish populations. Studies 

investigating the possible effects of 

sound (including seismic sound) on fish 

and invertebrate behavior have been 

conducted on both uncaged and caged 

animals (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. 

For marine invertebrates, behavioral 

changes could potentially affect such 

aspects as reproductive success, 

distribution, susceptibility to predation, 

and catchability by fisheries. Studies of 

squid indicated startle responses 

(McCauley et al., 2000a,b). In other 

cases, no behavioral impacts were noted 

(e.g., crustaceans in Christian et al., 

2003, 2004; DFO, 2004). There have 

been anecdotal reports of reduced catch 

rates of shrimp shortly after exposure to 

seismic surveys; however, other studies 

have not observed any significant 

changes in shrimp catch rate 

(Andriguetto-Filho et al., 2005). Parry 

and Gason (2006) reported no changes 

in rock lobster CPUE during or after 

seismic surveys off western Victoria, 

Australia, from 1978–2004. Any adverse 

effects on crustacean and cephalopod 

behavior or fisheries attributable to 

seismic survey sound depend on the 

species in question and the nature of the 

fishery (season, duration, fishing 

method). Additional information 

regarding the behavioral effects of 

seismic on invertebrates is contained in 

Appendix D (c) of L-DEO’s application. 

Summary of Behavioral Effects – As is 

the case with pathological and 

physiological effects of seismic on fish 

and invertebrates, available information 

is relatively scant and often 

contradictory. There have been welldocumented observations of fish and 

invertebrates exhibiting behaviors that 

appeared to be responses to exposure to 

seismic energy (i.e., startle response, 

change in swimming direction and 

speed, and change in vertical 

distribution), but the ultimate 

importance of those behaviors is 

unclear. Some studies indicate that such 

behavioral changes are very temporary, 

whereas others imply that fish might not 

resume pre-seismic behaviors or 

distributions for a number of days. 

There appears to be a great deal of interand intra-specific variability. In the case 

of finfish, three general types of 

behavioral responses have been 

identified: startle, alarm, and avoidance. 

The type of behavioral reaction appears 

to depend on many factors, including 

the type of behavior being exhibited 

before exposure, and proximity and 

energy level of sound source. 

During the proposed study, only a 

small fraction of the available habitat 

would be ensonified at any given time, 


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and fish species would return to their 

pre-disturbance behavior once the 

seismic activity ceased. The proposed 

seismic program is predicted to have 

negligible to low behavioral effects on 

the various life stages of the fish and 

invertebrates during its relatively short 

duration and extent. 

Because of the reasons noted above 

and the nature of the proposed 

activities, the proposed operations are 

not expected to have any habitat-related 

effects that could cause significant or 

long-term consequences for individual 

marine mammals or their populations or 

stocks. Similarly, any effects to food 

sources are expected to be negligible. 

Subsistence Activities 

Subsistence hunting and fishing 

continue to feature prominently in the 

household economies and social welfare 

of some Alaskan residents, particularly 

among those living in small, rural 

villages (Wolfe and Walker, 1987). 

Subsistence remains the basis for Alaska 

Native culture and community. In rural 

Alaska, subsistence activities are often 

central to many aspects o human 

existence from patterns of family life to 

artistic expression and community 

religious and celebratory activities. 

Marine mammals are hunted legally 

in Alaskan waters by coastal Alaska 

Natives. In SE Alaska, the only marine 

mammals that are hunted are Steller sea 

lions, harbor seals, and sea otters. Wolfe 

et al. (2004 in Angliss and Outlaw, 

2007) estimated that means of 959 and 

678 harbor seals from the SE Alaska and 

the Gulf of Alaska stock, respectively, 

harvested per year by Alaska Natives 

between 2000 and 2004, with 743 and 

747 seals, respectively, harvested in 

2004. Means of 3 and 191 Steller sea 

lions from the Eastern and Western 

Alaska stocks, respectively, were 

harvested per year by Alaska Natives 

between 2000 and 2004, with 5 and 137 

sea lions, respectively, harvested in 

2004. 

Sea otters are harvested by Alaska 

Native hunters from SE Alaska to the 

Aleutian Islands. The USFWS monitors 

the harvest of sea otters in Alaska. The 

mean annual subsistence takes from 

1996 to 2000 were 97, 297, and 301 

animals from the Southwest, 

Southcentral, and Southeast Alaska sea 

otter stocks, respectively (USFWS 2002 

in Angliss and Outlaw, 2007). 

The subsistence harvest of sea otters 

occurs year-round in coastal 

communities throughout SE Alaska and 

the northern GOA. However, there is a 

general reduction in harvest during the 

summer months. Hunters are required to 

obtain tags for sea otter pelts from 

designated USFWS taggers located in all 

harvesting villages. The geographical 

distribution of the harvest is difficult to 

determine because reports are generated 

by marking location; harvest location is 

generally not recorded. Harvests can 

take place from a large geographic area 

surrounding each sea otter harvesting 

village. 

Since 1992, the seasonal distribution 

of harbor seal takes by Alaska Natives 

has shown two distinct peaks, one 

during spring, and the other during fall 

and early winter (Wolfe et al., 2003). 

The peak harbor seal harvest season for 

villages in SE Alaska and the northern 

GOA varies, but in general the months 

of highest harvest are September 

through December, with a smaller peak 

in March. Harvests are traditionally low 

from May through August, when harbor 

seals are raising pups and molting in SE 

Alaska. The Steller sea lion harvest in 

SE Alaska and the northern GOA is low 

throughout the year. In 2002, the only 

harvests in SE Alaska occurred during 

March and November, and in the 

northern GOA and Prince William 

Sound, harvests occurred in July, 

November, and December (Wolfe et al., 

2003). 

Beluga whales do not occur regularly 

within the project area. Any occassional 

subsistence hunting of belugas that 

might occur in that area would be 

opportunistic hunting of extralimital 

animals. 

Gray whales are not hunted within 

the project area. Some of the gray 

whales that migrate through SE Alaska 

in spring and late autumn are hunted in 

Russian waters during summer, and a 

very limited subsistence has occurred in 

recent years off Washington. Any smallscale disturbance effects that might 

occur in SE Alaska as a result of LDEO’s project would have no effect on 

the hunts for gray whales in those 

distant locations. 

The proposed survey could 

potentially impact the availability of 

marine mammals for harvest in a very 

small area immediately around the 

Langseth, and for a very short time 

period during seismic activities. 

Considering the limited time and 

locations for the planned seismic 

surveys, most of which are well offshore 

(Figure 1 of L-DEO’s application), the 

proposed survey is not expected to have 

any significant impacts to the 

availability of Steller sea lions, harbor 

seals, or sea otters for subsistence 

harvest. Nonetheless, L-DEO will 

coordinate its activities with local 

communities, so that seismic operations 

will be conducted outside of subsistence 

hunting times and areas if possible. 

TABLE 4. THE ESTIMATED 2002 HARVEST OF HARBOR SEALS AND STELLER SEA LIONS BY ALASKA NATIVE COMMUNITIES

NEAR THE PROPOSED STUDY AREA IN THE GULF OF ALASKA. 

Village Estimated Total Harvest of Harbor Seal 1

Estimated Total Harvest of 

Steller Sea Lion 1 Peak of Harbor Seal Harvest 2

Southeast Alaska 

Pelican 

1.8 0.0 October 

Yakutat 137.5 0.0 March 

Northern GOA and PWS 

Chenega Bay 

10.5 0.0 August 

Cordova 108.5 3.5 February 

Tatilek 14.9 0.0 February and March 3

Valdez 50.0 0.0 December 

1 Includes estimates of both harvested and struck-and-lost animals. Totals are estimated from incomplete household surveys and were multiplied by a correction factor for missed households, which result in fractional estimates rather than whole number counts. 2 Maximum number harvested in 2002 reported by Wolfe et al. (2003). 

3 Peak harvest in 2000 (Wolfe, 2001). 


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Subsistence fisheries, on average, 

provide about 230 pounds (104.5 kg) of 

food per person per year in rural Alaska 

(Wolfe, 2000). Of the estimated 43.7 

million pounds of wild food harvested 

in rural Alaska communities annually, 

subsistence fisheries contributed 

approximately 60 percent from finfish 

and 2 percent from shellfish. In the rural 

communities along the GOA, salmon 

species are the most targeted 

subsistence fish. 

In 2006, there were 609 residents in 

the Yakutat Region eligible to 

participate in the Alaska subsistence 

fishery. The Yakutat Region subsistence 

fishers rely mostly upon Pacific halibut, 

with 5,079–16,561 kg taken in annual 

catch from 2003 to 2006 (Fall et al., 

2007). Halibut typically are taken with 

a setline or hand-operated fishing gear, 

with the majority of the catch coming 

from the setline gear. The halibut 

fishery is open for subsistence harvest 

from 1 February to 31 December unless 

limited for expanded by emergency 

order. Salmon are also significant 

importance to subsistence fisheres in 

the Yakutat Region, with 6,918 

harvested there in 2003 (ADFG, 2005). 

Set gillnets are thee preferred 

subsistence harvest method for salmon, 

and there are not restrictions on specific 

streams, nor are there daily or annual 

limits to the number of fish taken; there 

are restrictions to keep subsistence and 

commercial fisheries separate (ADFG, 

2005). Bottomfish, Pacific herring, 

smelt, and crustaceans are also caught 

by substance fishers in the Yakutat 

Region. 

Seismic surveys can, at times, cause 

changes in the catchability of fish. LDEO will minimize the potential to 

negatively impact the subsistence fish 

harvest by avoiding areas where 

subsistence fishers are fishing. 

Additionally, L-DEO will consult with 

each village near the planned project 

area to identify and avoid areas of 

potential conflict. These consultations 

will include all marine subsistence 

activities (marine mammals and 

fisheries). 

Proposed Mitigation and Monitoring 

Mitigation and monitoring measures 

proposed to be implemented for the 

proposed seismic survey have been 

developed and refined during previous 

L-DEO seismic studies and associated 

environmental assessments (EAs), IHA 

applications, and IHAs. The mitigation 

and monitoring measures described 

herein represent a combination of the 

procedures required by past IHAs for 

other similar projects and on 

recommended best practices in 

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

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

The measures are described in detail 

below. 

Mitigation measures that will be 

adopted during the proposed STEEP 

survey include: (1) speed or course 

alteration, provided that doing so will 

not compromise operational safety 

requirements; (2) power-down 

procedures; (3) shutdown procedures; 

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

procedures for situations or species of 

particular concern, e.g., avoidance of 

critical habitat around Steller sea lion 

rookeries and haul-outs (see ‘‘shut-down 

procedures’’ and ‘‘special procedures for 

situations and species of particular 

concern,’’ below). The thresholds used 

for estimating take are also used in 

connection with proposed mitigation. 

Vessel-based Visual Monitoring 

Marine Mammal Visual Observers 

(MMVOs) will be based aboard the 

seismic source vessel and will watch for 

marine mammals near the vessel during 

daytime airgun operations and during 

start-ups of airguns at night. MMVOs 

will also watch for marine mammals 

near the seismic vessel for at least 30 

minutes prior to the start of airgun 

operations after an extended shutdown 

of the airguns. When feasible, MMVOs 

will also make observations during 

daytime periods when the seismic 

system is not operating for comparison 

of sighting rates and animal behavior 

with vs. without airgun operations. 

Based on MMVO observations, the 

airguns will be powered down, or if 

necessary, shut down completely (see 

below), when marine mammals are 

detected within or about to enter a 

designated EZ. The MMVOs will 

continue to maintain watch to 

determine when the animal(s) are 

outside the safety radius, and airgun 

operations will not resume until the 

animal has left that zone. The predicted 

distances for the safety radius’ are listed 

according to the sound source, water 

depth, and received isopleth in Table 1. 

During seismic operations in the 

GOA, at least three MMVOs will be 

based aboard the Langseth. MMVOs will 

be appointed by L-DEO with NMFS 

concurrence. At least one MMVO, and 

when practical two, will monitor the EZ 

for marine mammals during ongoing 

daytime operations and nighttime 

startups of the airguns. Use of two 

simultaneous MMVOs will increase the 

proportion of the animals present near 

the source vessel that are detected. 

MMVO(s) will be on duty in shifts of 

duration no longer than 4 hours. The 

vessel 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 regarding how to 

do so. 

The Langseth is a suitable platform for 

marine mammal observations. When 

stationed on the observation platform, 

the eye level will be approximately 17.8 

m (58.4 ft) above sea level, and the 

observer will have a good view around 

the entire vessel. During daytime, the 

MMVO(s) will scan the area around the 

vessel systematically with reticle 

binoculars (e.g., 7x50 Fujinon), Big-eye 

binoculars (25x150), and with the naked 

eye. During darkness, night vision 

devices (NVDs) will be available (ITT 

F500 Series Generation 3 binocularimage intensifier or equivalent), when 

required. Laser rangefinding binoculars 

(Leica LRF 1200 laser rangefinder or 

equivalent) will be available to assist 

with distance estimation. Those are 

useful in training MMVOs to estimate 

distances visually, but are generally not 

useful in measuring distances to 

animals directly. 

Speed or Course Alteration – If a 

marine mammal is detected outside the 

safety radius and, based on its position 

and the relative motion, is likely to 

enter the exclusion zone, the vessel’s 

speed and/or direct course may be 

changed. This would be done if 

practicable while minimizing the effect 

on th planned science objectives. The 

activities and movements of the marine 

mammal(s) (relative to the seismic 

vessel) will then be closely monitored to 

determine whether the animals is 

approaching the applicable EZ. If the 

animal appears likely to enter the EZ, 

further mitigative actions will be taken, 

i.e., either further course alterations or 

a power down or shut down of the 

airguns. Typically, during seismic 

operations, major course and speed 

adjustments are often impractical when 

towing long seismic streamers and large 

source arrays, thus alternative 

mitigation measures (see below) will 

need to be implemented. 

Power-down Procedures – A powerdown involves reducing the number of 

operating airguns in use to minimize the 

EZ, so that marine mammals are no 

longer in or about to enter this zone. A 

power-down of the airgun array to a 

reduced number of operating airguns 

may also occur when the vessel is 

moving from one seismic line to 

another. During a power down for 

mitigation, one airgun will be operated. 

The continued operation of at least one 

airgun is intended to alert marine 

mammals to the presence of the seismic 

vessel in the area. In contrast, a shut 

down occurs when all airgun activity is 

suspended. 


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Federal Register / Vol. 73, No. 151 / Tuesday, August 5, 2008 / Notices 45425 

If a marine mammal is detected 

outside the EZ but is likely to enter it, 

and if the vessel’s speed and/or course 

cannot be changed to avoid the 

animal(s) entering the EZ, the airguns 

will be powered down to a single airgun 

before the animal is within the EZ. 

Likewise, if a mammal is already within 

the EZ when first detected, the airguns 

will be powered down immediately. 

During a power down of the airgun 

array, the 40–in3 airgun will be 

operated. If a marine mammal is 

detected within or near the smaller EZ 

around that single airgun (see Table 1 of 

L-DEO’s application and Table 1 above), 

all airguns will be shutdown (see next 

subsection). 

Following a power down, airgun 

activity will not resume until the marine 

mammal is outside the EZ for the full 

array. The animal will be considered to 

have cleared the EZ if it: 

(1) Is visually observed to have left 

the EZ; or 

(2) Has not been seen within the EZ 

for 15 minutes in the case of small 

odontocetes and pinnipeds; or 

(3) Has not been seen within the EZ 

for 30 minutes in the case of mysticetes 

and large odontocetes, including sperm, 

pygmy sperm, dwarf sperm, and beaked 

whales; or 

During airgun operations following a 

power-down (or shut down) and 

subsequent animal departure as above, 

the airgun array will resume operations 

following ramp-up procedures 

described below. 

Shutdown Procedures – The operating 

airgun(s) will be shutdown if a marine 

mammal is detected within or 

approaching the EZ for the thenoperating single 40 in3 airgun source 

while the airgun array is at full volume 

or during a power down. Airgun activity 

will not resume until the marine 

mammal has cleared the EZ or until the 

MMVO is confident that the animal has 

left the vicinity of the vessel. Criteria for 

judging that the animal has cleared the 

EZ will be as describing in the 

preceding subsection. 

Ramp-up Procedures – A ramp-up 

procedure will be followed when the 

airgun array begins operating after a 

specified-duration period without 

airgun operations or when a power 

down has exceeded that period. It is 

proposed that, for the present cruise, 

this period would be approximately 7 

minutes. This period is based on the 

modeled 180–dB radius for the 36–

airgun array (see Table 1 of L-DEO’s 

application and Table 1 here) in relation 

to the planned speed of the Langseth 

while shooting. Similar periods 

(approximately 8–10 minutes) were 

used during previous L-DEO surveys. 

Ramp-up will begin with the smallest 

airgun in the array (40 in3). Airguns will 

be added in a sequence such that the 

source level of the array will increase in 

steps not exceeding 6 dB per 5–minute 

period over a total duration of 

approximately 20–25 minutes. During 

ramp-up, the MMVOs will monitor the 

EZ, and if marine mammals are sighted, 

a course/speed change, power down, or 

shutdown will be implemented as 

though the full array were operational. 

If the complete EZ has not been 

visible for at least 30 min prior to the 

start of operations in either daylight or 

nighttime, ramp up will not commence 

unless at least one airgun (40 in3 or 

similar) has been operating during the 

interruption of seismic survey 

operations. Given these provisions, it is 

likely that the airgun array will not be 

ramped up from a complete shut down 

at night or in thick fog, because the 

other part of the EZ for that array will 

not be visible during those conditions. 

If one airgun has operated during a 

power down period, ramp up to full 

power will be permissible at night or in 

poor visibility, on the assumption that 

marine mammals will be alerted to the 

approaching seismic vessel by the 

sounds from the single airgun and could 

move away if they choose. Ramp up of 

the airguns will not be initiated if a 

marine mammal is isghted within or 

near the applicable EZ during the day or 

close to the vessel at night. 

Special Procedures for Situations and 

Species of Particular Concern 

Several species of particular concern 

could occur in the study area. Special 

mitigation procedures will be used for 

those species, as follows: 

(1) Critical habitat around Steller sea 

lion rookeries and haul-outs will be 

avoided; 

(2) The airguns will be shut down if 

a North Pacific right whale is sighted at 

any distance from the vessel; 

(3) Concentrations of humpack 

whales, fin whales, and sea otters will 

be avoided; 

(4) The seismic vessel will avoid areas 

where subsistence fishers are fishing; 

and 

(5) Because the sensitivity of beaked 

whales, approach to slopes and 

submarine canyons will be minimized, 

if possible. There are no submarine 

canyons in or near the study area, and 

only a limited amount of airgun 

operations is planned over slope during 

the proposed survey (Figure 1 of LDEO’s application). 

Passive Acoustic Monitoring 

Passive Acoustic Monitoring (PAM) 

will take place to complement the visual 

monitoring program. Visual monitoring 

typically is not effective during periods 

of bad weather or at night, and even 

with good visibility, is unable to detect 

marine mammals when they are below 

the surface or beyond visual range. 

Acoustical monitoring can be used in 

addition to visual observations to 

improve detection, identification, 

localization, and tracking of cetaceans. 

The acoustic monitoring will serve to 

alert visual observers (if on duty) when 

vocalizing cetaceans are detected. It is 

only useful when marine mammals call, 

but it can be effective either by day or 

by night and does not depend on good 

visibility. It will be monitored in real 

time so visual observers can be advised 

when cetaceans are detected. When 

bearings (primary and mirror-image) to 

calling cetacean(s) are determined, the 

bearings will be relayed to the visual 

observer to help him/her sight the 

calling animal(s). 

The PAM system consists of hardware 

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

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

low-noise, towed hydrophone array that 

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

faired cable. The array will be deployed 

from a winch located on the back deck. 

A deck cable will connect from th 

winch to the main computer lab where 

the acoustic station and signal condition 

and processing system will be located. 

Th lead-in from the hydrophone array is 

approximately 400 m (1,312 ft) long, 

and the active part of the hydrophone is 

approximately 56 m (184 ft) long. The 

hydrophone array is typically towed at 

depths <20 m (65.6 ft). 

The towed hydrophone array will be 

monitored 24 hours per day while at the 

survey area during airgun operations, 

and also during most periods when the 

Langseth is underway while the airguns 

are not operating. One Marine Mammal 

Observer (MMO) will monitor the 

acoustic detection system at any one 

time, by listening to the signals from 

two channels via headphones and/or 

speakers and watching the real time 

spectrographic display for frequency 

ranges produced by cetaceans. MMOs 

monitoring the acoustical data will be 

on shift for 1–6 hours. Besides the 

‘‘visual’’ MMOs, an additional MMO 

with primary responsibility for PAM 

will also be aboard. However, all MMOs 

are expected to rotate through the PAM 

position, although the most experienced 

with acoustics will be on PAM duty 

more frequently. 

When a vocalization is detected, the 

acoustic MMO will, if visual 

observations are in progress, contact the 

MMVO immediately to alert him/her to 

the presence of the cetacean(s) (if they 

have not already been seen), and to 


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45426 Federal Register / Vol. 73, No. 151 / Tuesday, August 5, 2008 / Notices 

allow a power down or shutdown to be 

initiated, if required. The information 

regarding the call will be entered into a 

database. The data to be entered include 

an acoustic encounter identification 

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. 

MMVO Data and Documentation 

MMVOs will record data to estimate 

the numbers of marine mammals 

exposed to various received sound 

levels and to document any apparent 

disturbance reactions or lack thereof. 

Data will be used to estimate the 

numbers of mammals potentially 

‘‘taken’’ by harassment. They will also 

provide information needed to order a 

power down or shutdown of airguns 

when marine mammals are within or 

near the EZ. 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 (shooting or not), 

sea state, visibility, cloud cover, 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, as well as 

information regarding airgun power 

down and shutdown, will be recorded 

in a standardized format. Data will be 

entered into a custom 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. Preliminary reports will be 

prepared during the field program and 

summaries forwarded to the operating 

institution’s shore facility and to NSF 

weekly or more frequently. MMVO 

observations will provide the following 

information: 

(1) The basis for decisions about 

powering down or shutting down airgun 

arrays. 

(2) Information needed to estimate the 

number of marine mammals potentially 

’taken by harassment.’ These data will 

be reported to NMFS per terms of 

MMPA authorizations or regulations. 

(3) Data on the occurrence, 

distribution, and activities of marine 

mammals in the area where the seismic 

study is conducted. 

(4) Data on the behavior and 

movement patterns of marine mammals 

seen at times with and without seismic 

activity. 

Proposed Reporting 

A report will be submitted to NMFS 

within 90 days after the end of the 

cruise. The report will describe the 

operations that were conducted and 

sightings of marine mammals near the 

operations. The report will be submitted 

to NMFS, providing full documentation 

of methods, results, and interpretation 

pertaining to all monitoring. The 90–day 

report will summarize the dates and 

locations of seismic operations, all 

marine mammal sightings (dates, times, 

locations, activities, associated seismic 

survey activities). The report will also 

include estimates of the amount and 

nature of potential ‘‘take’’ of marine 

mammals by harassment or in other 

ways. 

Endangered Species Act (ESA) 

Under section 7 of the ESA, NSF has 

begun consultation with the NMFS, 

Office of Protected Resources, 

Endangered Species Division on this 

proposed seismic survey. NMFS will 

also consult on the issuance of an IHA 

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

for this activity. Consultation will be 

concluded prior to a determination on 

the issuance of the IHA. 

National Environmental Policy Act 

(NEPA) 

NSF prepared an Environmental 

Assessment of a Marine Geophysical 

Survey by the R/V Marcus G.Langseth in 

the Gulf of Alaska, September 2008. 

NMFS will either adopt NSF’s EA or 

conduct a separate NEPA analysis, as 

necessary, prior to making a 

determination of the issuance of the 

IHA. 

Preliminary Determinations 

NMFS has preliminarily determined 

that the impact of conducting the 

seismic survey in the Gulf of Alaska 

may result, at worst, in a temporary 

modification in behavior (Level B 

Harassment) of small numbers of 20 

species of marine mammals. Further, 

this activity is expected to result in a 

negligible impact on the affected species 

or stocks. The provision requiring that 

the activity not have an unmitigable 

adverse impact on the availability of the 

affected species or stock for subsistence 

uses is not implicated for this proposed 

action. 

For reasons stated previously in this 

document, this determination is 

supported by: (1) the likelihood that, 

given sufficient notice through 

relatively slow ship speed, marine 

mammals are expected to move away 

from a noise source that is annoying 

prior to its becoming potentially 

injurious; (2) the fact that pinnipeds 

would have to be closer than 300 m 

(0.19 mi) in deep water, 450 m (0.28 mi) 

at intermediate depths, or 2,182 m (1.36 

mi) in shallow water when a single 

airgun is in use from the vessel to be 

exposed to levels of sound (190 dB) and 

to have even a minimal chance of 

causing TTS; (3) the fact that cetaceans 

would have to be closer than 950 m (0.6 

mi) in deep water, 1,425 m (0.9 mi) at 

intermediate depths, and 3,694 m (2.3 

mi) in shallow water when the full array 

is in use at a 9 m (29.5 ft) tow depth 

from the vessel to be exposed to levels 

of sound (180 dB) believed to have even 

a minimal chance of causing TTS; (4) 

the fact that marine mammals would 

have to be closer than 6,000 m (3.7 mi) 

in deep water, 6,667 m (4.1 mi) at 

intermediate depths, and 8,000 m (4.9 

mi) in shallow water when the full array 

is in use at a 9 m (29.5 ft) tow depth 

from the vessel to be exposed to levels 

of sound (160 dB) believed to have even 

a minimal chance of causing TTS; and 

(5) the likelihood that marine mammal 

detection ability by trained observers is 

high at that short distance from the 

vessel. As a result, no take by injury or 

death is anticipated, and the potential 

for temporary or permanent hearing 

impairment is very low and will be 

avoided through the incorporation of 

the proposed mitigation measures. 

While the number of potential 

incidental harassment takes will depend 

on the distribution and abundance of 

marine mammals in the vicinity of the 

survey activity, the number of potential 

harassment takings is estimated to be 

small, less than a few percent of any of 

the estimated population sizes, and has 

been mitigated to the lowest level 

practicable through incorporation of the 

measures mentioned previously in this 

document. 

Proposed Authorization 

As a result of these preliminary 

determinations, NMFS proposes to issue 

an IHA to L-DEO for conducting a 

marine geophysical survey in the Gulf of 


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Federal Register / Vol. 73, No. 151 / Tuesday, August 5, 2008 / Notices 45427 

Alaska from August-September, 2008, 

provided the previously mentioned 

mitigation, monitoring, and reporting 

requirements are incorporated. 

Dated: July 30, 2008. 

James H. Lecky, 

Director, Office of Protected Resources, 

National Marine Fisheries Service. 

[FR Doc. E8–17949 Filed 8–4–08; 8:45 am] 

BILLING CODE 3510–22–S 

DEPARTMENT OF DEFENSE 

GENERAL SERVICES 

ADMINISTRATION 

NATIONAL AERONAUTICS AND 

SPACE ADMINISTRATION 

[OMB Control No. 9000–0142] 

Federal Acquisition Regulation; 

Information Collection; Past 

Performance Information 

AGENCIES: Department of Defense (DOD), 

General Services Administration (GSA), 

and National Aeronautics and Space 

Administration (NASA). 

ACTION: Notice of request for public 

comments regarding an extension to an 

existing OMB clearance (9000–0142). 

SUMMARY: Under the provisions of the 

Paperwork Reduction Act of 1995 (44 

U.S.C. Chapter 35), the Federal 

Acquisition Regulation (FAR) 

Secretariat will be submitting to the 

Office of Management and Budget 

(OMB) a request to review and approve 

an extension of a currently approved 

information collection requirement 

concerning past performance 

information. The clearance currently 

expires on November 30, 2008. 

Public comments are particularly 

invited on: Whether this collection of 

information is necessary for the proper 

performance of functions of the FAR, 

and whether it will have practical 

utility; whether our estimate of the 

public burden of this collection of 

information is accurate, and based on 

valid assumptions and methodology; 

ways to enhance the quality, utility, and 

clarity of the information to be 

collected; and ways in which we can 

minimize the burden of the collection of 

information on those who are to 

respond, through the use of appropriate 

technological collection techniques or 

other forms of information technology. 

DATES: Submit comments on or before 

October 6, 2008. 

ADDRESSES: Submit comments regarding 

this burden estimate or any other aspect 

of this collection of information, 

including suggestions for reducing this 

burden to the General Services 

Administration, FAR Secretariat (VPR), 

1800 F Street, NW, Room 4041, 

Washington, DC 20405. 

FOR FURTHER INFORMATION CONTACT: Ms. 

Jeritta Parnell, Contract Policy Division, 

at GSA (202) 501–4082. 

SUPPLEMENTARY INFORMATION: 

A. Purpose 

Past performance information is 

relevant information, for future source 

selection purposes, regarding a 

contractor’s actions under previously 

awarded contracts. When past 

performance is to be evaluated, the rule 

states that the solicitation shall afford 

offerors the opportunity to identify 

Federal, state and local government, and 

private contracts performed by offerors 

that were similar in nature to the 

contract being evaluated. 

B. Annual Reporting Burden 

Respondents: 150,000. 

Responses Per Respondent: 4. 

Annual Responses: 600,000. 

Hours Per Response: 2. 

Total Burden Hours: 1,200,000. 

OBTAINING COPIES OF 

PROPOSALS: Requesters may obtain a 

copy of the information collection 

documents from the General Services 

Administration, FAR Secretariat (VPR), 

1800 F Street, N.W., Room 4041, 

Washington, DC 20405, telephone (202) 

501–4755. Please cite OMB Control No. 

9000–0142, Past Performance 

Information, in all correspondence. 

Dated: July 29, 2008. 

Al Matera, 

Director, Office of Acquisition Policy. 

[FR Doc. E8–17901 Filed 8–4–08; 8:45 am] 

BILLING CODE 6820–EP–S 

DEPARTMENT OF EDUCATION 

Submission for OMB Review; 

Comment Request 

AGENCY: Department of Education. 

SUMMARY: The IC Clearance Official, 

Regulatory Information Management 

Services, Office of Management invites 

comments on the submission for OMB 

review as required by the Paperwork 

Reduction Act of 1995. 

DATES: Interested persons are invited to 

submit comments on or before 

September 4, 2008. 

ADDRESSES: Written comments should 

be addressed to the Office of 

Information and Regulatory Affairs, 

Attention: Education Desk Officer, 

Office of Management and Budget, 725 

17th Street, NW., Room 10222, 

Washington, DC 20503. Commenters are 

encouraged to submit responses 

electronically by e-mail to 

oira_submission@omb.eop.gov or via fax 

to (202) 395–6974. Commenters should 

include the following subject line in 

their response ‘‘Comment: [insert OMB 

number], [insert abbreviated collection 

name, e.g., ‘‘Upward Bound 

Evaluation’’].’’ Persons submitting 

comments electronically should not 

submit paper copies. 

SUPPLEMENTARY INFORMATION: Section 

3506 of the Paperwork Reduction Act of 

1995 (44 U.S.C. Chapter 35) requires 

that the Office of Management and 

Budget (OMB) provide interested 

Federal agencies and the public an early 

opportunity to comment on information 

collection requests. OMB may amend or 

waive the requirement for public 

consultation to the extent that public 

participation in the approval process 

would defeat the purpose of the 

information collection, violate State or 

Federal law, or substantially interfere 

with any agency’s ability to perform its 

statutory obligations. The IC Clearance 

Official, Regulatory Information 

Management Services, Office of 

Management, publishes that notice 

containing proposed information 

collection requests prior to submission 

of these requests to OMB. Each 

proposed information collection, 

grouped by office, contains the 

following: (1) Type of review requested, 

e.g., new, revision, extension, existing 

or reinstatement; (2) Title; (3) Summary 

of the collection; (4) Description of the 

need for, and proposed use of, the 

information; (5) Respondents and 

frequency of collection; and (6) 

Reporting and/or Recordkeeping 

burden. OMB invites public comment. 

Dated: July 30, 2008 

Angela C. Arrington, 

IC Clearance Official, Regulatory Information 

Management Services, Office of Management. 

Office of Elementary and Secondary 

Education 

Type of Review: New. 

Title: Migrant Student Information 

Exchange User Application Form. 

Frequency: On Occasion. 

Affected Public: Individuals or 

household; State, Local, or Tribal Gov’t, 

SEAs or LEAs. 

Reporting and Recordkeeping Hour 

Burden: 

Responses: 9,800. 

Burden Hours: 4,900. 

Abstract: The collection is the user 

application form that is completed by 

State migrant education program staff 

who need to obtain access to the 

Migrant Student Information Exchange 

(MSIX) system. MSIX User 


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