25830 Federal Register / Vol. 77, No. 84 / Tuesday, May 1, 2012 / Notices 

DEPARTMENT OF COMMERCE 

National Oceanic and Atmospheric 

Administration 

RIN 0648–XY11 

Takes of Marine Mammals Incidental to 

Specified Activities; Taking Marine 

Mammals Incidental to Marine Seismic 

Survey in the Beaufort Sea, Alaska 

AGENCY: National Marine Fisheries 

Service (NMFS), National Oceanic and 

Atmospheric Administration (NOAA), 

Commerce. 

ACTION: Notice; proposed incidental 

harassment authorization; request for 

comments. 

SUMMARY: NMFS received an 

application from BP Exploration 

(Alaska), Inc. (BP) for an Incidental 

Harassment Authorization (IHA) to take 

marine mammals, by harassment only, 

incidental to a proposed 3-dimensional 

(3D) ocean bottom cable (OBC) seismic 

survey in the Simpson Lagoon area of 

the Alaskan Beaufort Sea during the 

open water season of 2012. Pursuant to 

the Marine Mammal Protection Act 

(MMPA), NMFS is requesting comments 

on its proposal to issue an IHA to BP to 

take, by Level B harassment, 11 species 

of marine mammals during the specified 

activity. 

DATES: Comments and information must 

be received no later than May 31, 2012. 

ADDRESSES: Comments on the 

application should be addressed to 

Tammy Adams, Acting Chief, Permits 

and Conservation Division, Office of 

Protected Resources, National Marine 

Fisheries Service, 1315 East-West 

Highway, Silver Spring, MD 20910. The 

mailbox address for providing email 

comments is ITP.guan@noaa.gov. NMFS 

is not responsible for email comments 

sent to addresses other than the one 

provided here. Comments sent via 

email, including all attachments, must 

not exceed a 10-megabyte file size. 

Instructions: All comments received 

are a part of the public record and will 

generally be posted to http:// 

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

incidental.htm#applications without 

change. All Personal Identifying 

Information (for example, name, 

address, etc.) voluntarily submitted by 

the commenter may be publicly 

accessible. Do not submit Confidential 

Business Information or otherwise 

sensitive or protected information. 

A copy of the application 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 also 

be viewed, by appointment, during 

regular business hours, at the 

aforementioned address. 

FOR FURTHER INFORMATION CONTACT: 

Shane Guan, Office of Protected 

Resources, NMFS, (301) 427–8401. 

SUPPLEMENTARY INFORMATION: 

Background 

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

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

the Secretary of Commerce to allow, 

upon request, the incidental, but not 

intentional, taking of small numbers of 

marine mammals by U.S. citizens who 

engage in a specified activity (other than 

commercial fishing) within a specified 

geographical region if certain findings 

are made and either regulations are 

issued or, if the taking is limited to 

harassment, a notice of a proposed 

authorization is provided to the public 

for review. 

Authorization for incidental takings 

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 U.S. can apply for 

an authorization to incidentally take 

small numbers of marine mammals by 

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 issue or deny 

the authorization. 

Except with respect to certain 

activities not pertinent here, the MMPA 

defines ‘‘harassment’’ as: 

any act of pursuit, torment, or annoyance 

which (i) has the potential to injure a marine 

mammal or marine mammal stock in the wild 

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

potential to disturb a marine mammal or 

marine mammal stock in the wild by causing 

disruption of behavioral patterns, including, 

but not limited to, migration, breathing, 

nursing, breeding, feeding, or sheltering 

[‘‘Level B harassment’’]. 

Summary of Request 

NMFS received an application on 

December 20, 2011, from BP for the 

taking, by harassment, of marine 

mammals incidental to a 3D OBC 

seismic survey in the Simpson Lagoon 

area of the Alaskan Beaufort Sea during 

the open water season of 2012. 

Description of the Specified Activity 

The proposed seismic survey utilizes 

receivers (hydrophones and geophones) 

connected to a cable that would be 

deployed from a vessel to the seabed or 

would be inserted in the seabed in very 

shallow water areas near the shoreline. 

The generation of 3D seismic images 

requires the deployment of many 

parallel cables spaced close together 

over the area of interest. Therefore, OBC 

seismic surveys require the use of 

multiple vessels for cable deployment 

and recovery, data recording, airgun 

operation, re-supply, and support. The 

proposed 3D OBC seismic survey in 

Simpson Lagoon would be conducted 

by CGGVeritas. 

Seismic Source Arrays 

A total of three seismic source vessels 

(two main source vessels and one mini 

source vessel) would be used during the 

proposed survey. The sources would be 

arrays of sleeve airguns. Each main 

source vessel would carry an array that 

consists of two sub-arrays. Each subarray contains eight 40 in3 airguns, 

totaling 16 guns per main source vessel 

with a total discharge volume of 2 × 320 

in3, or 640 in3. This 640 in3 array has 

an estimated source level of ∼223 dB re 

1 mPa (rms). The mini source vessel 

would contain one array with eight 40 

in3 airguns for a total discharge volume 

of 320 in3. The estimated source level of 

this 320 in3 array is 212 dB re 1 mPa 

(rms). 

The arrays of the main source vessels 

would be towed at a distance of ∼30 feet 

(ft, or 10 m) from the stern at 6 ft (2 m) 

depth, which is remotely adjustable if 

needed. The array of the mini source 

vessel would be towed at a distance of 

∼20 ft (7 m) from the stern at 3 ft (1 m) 

depth, also remotely adjustable when 

needed. The source vessels will travel 

along pre-determined lines with a speed 

varying from ∼1 to 5 knots, mainly 

depending on the water depth. To limit 

the duration of the total survey, the 

source vessels would be operating in a 

flip-flop mode, with the operating 

source vessels alternating shots; this 

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means that one vessel discharges 

airguns when the other vessel is 

recharging. Outside the barrier islands, 

the two main source vessels would be 

operating with expected shot intervals 

of 8 to 10 seconds, resulting in a shot 

every 4 to 5 seconds due to the flip-flop 

mode of operation. Inside the barrier 

islands all three vessels (the two main 

source vessels and the mini vessel) may 

be operating at the same time in this 

manner. The exact shot intervals would 

depend on the compressor capacity, 

which determines the time needed for 

the airguns to be recharged. Seismic 

data acquisition would be conducted 

24 hours per day. 

Receivers and Recording Units 

The survey area in Simpson Lagoon 

has water depths of 0 to 9 ft (0 to 3 m) 

between the shore and barrier islands 

and 3 to 45 ft (1 to 15 m) depths north 

of the barrier islands. Because different 

types of receivers would be used for 

different habitats, the survey area is 

categorized by the terms onshore, 

islands, surf-zone and offshore. Onshore 

is the area from the coastline inland. 

Islands are the barrier islands. Surf zone 

is the 0 to 6 ft (0 to 2 m) water depths 

along the onshore coastline. Offshore is 

defined as depths of 3 ft (1 m) or more. 

There is a zone between 3 and 6 ft (1 

and 2 m) which may be categorized both 

as surf zone and as offshore. 

The receivers that would be deployed 

in water consist of multiple 

hydrophones and recorder units (Field 

Digitizing Units or FDUs) placed on 

Sercel ULS cables. Approximately 5,000 

hydrophones would be connected to the 

ULS cable at a minimum of 82.5 ft 

(27.5 m) intervals and secured to the 

ocean bottom cable. Surface markers 

and acoustic pingers will be attached to 

the cable at various intervals to ensure 

that the battery packs can be located and 

retrieved when needed and to determine 

exact positions for the hydrophones. 

This equipment would be deployed and 

retrieved with cable boats. The data 

received at each FDU would be 

transmitted through the cables to a 

recorder for further processing. This 

recorder will be installed on a boatbarge combination and positioned close 

to the area where data are being 

acquired. While recording, the boatbarge combination is stationary and 

expected to utilize a two or four point 

anchoring system. 

In the surf-zone, receivers 

(hydrophones or geophones) would be 

bored or flushed up to 12 ft (4 m) below 

the seabed. These receivers will 

transmit data through a cable (as 

described above) and have an attached 

line to facilitate retrieval after recording 

is completed. 

Autonomous recorders (nodes) would 

be used onshore and on the islands. The 

node is located on the ground and its 

geophone would be inserted into the 

ground by hand with the use of a 

planting pole. Deployment of the 

autonomous receiver units would be 

done by a lay-out crew on the ground 

using helicopters for personnel and 

equipment transport and/or approved 

summer travel vehicles (onshore) and a 

support boat (for the islands). Data from 

nodes can be remotely retrieved from a 

distance (up to a kilometer). Retrieval of 

data may be from a boat or a helicopter. 

Equipment would be picked up after 

recording is complete. 

Survey Design 

The total area of the proposed seismic 

survey is approximately 110 mi 2, which 

includes onshore, surf-zone, barrier 

islands, and offshore (see Figure 1.2 of 

the BP’s IHA application). For the 

proposed survey, the receiver cables 

with hydrophones and recording units 

would be oriented in an east-west 

direction. A total of approximately 44 

receiver lines would be deployed at the 

seafloor with 1,100–1,650 ft (367–550 

m) line spacing. Total receiver line 

length would be approximately 500 

miles (825 km). The source vessel 

would travel perpendicular over the 

offshore receiver cables along lines 

oriented in a north-south direction. 

These lines would have a length of 

approximately 3.75 miles (6.2 km) and 

a minimum spacing of 660 ft (220 m). 

The total length of all source lines is 

approximately 4,000 miles (6,600 km), 

including line turns. 

The position of each receiver 

deployed onshore, in the surf zone and 

on the barrier islands will be 

determined using Global Positioning 

System (GPS) positioning units. Due to 

the variable bathymetry of the survey 

area, determining positions of receivers 

deployed in water may require more 

than one technique. A combination of 

Ocean Bottom Receiver Location 

(OBRL), GPS and acoustic pingers will 

be used. For OBRL, the source vessel 

fires a precisely positioned single 

energy source multiple times along 

either side of the receiver cables. 

Production data may also be used 

instead of dedicated OBRL acquisition. 

Multiple energy sources are used to 

triangulate a given receiver position. In 

addition, Sonardyne acoustical pingers 

would be located at predetermined 

intervals on the receiver lines. The 

pingers are located on the ULS cables 

and transmit a signal to a transponder 

mounted on a vessel. This allows for an 

interpolation of the receiver locations 

between the acoustical pingers on the 

ULS cable and also serves as a 

verification of the OBRL method. The 

Sonardyne pingers transmit at 19–36 

kHz and have a source level of 188–193 

dB re mPa at 1m. 

Vessels and Other Equipment 

The proposed Simpson Lagoon OBC 

seismic survey would involve 14 to 16 

vessels, as listed in Table 1 below. The 

contracting of vessels has not been 

finalized to date. However, BP states it 

would contract vessels with parameters 

similar to those described in this table. 

If contracted vessels differ significantly 

from those described, BP would submit 

an amendment to address these changes 

where required. 

TABLE 1—SUMMARY OF NUMBER AND TYPE OF VESSELS INVOLVED IN THE PROPOSED SIMPSON LAGOON OBC SEISMIC

SURVEY

[The dimensions provided are approximate] 

Vessel type Number Dimensions Main activity Frequency 

Source Vessel: Main ..... 2 71 × 20 ft ...................... Seismic data acquisition inside and outside barrier islands.24-hr operation. 

Source Vessel: Mini ...... 1 55 × 15 ft ...................... Seismic data acquisition inside barrier islands .. 24-hr operation. 

Recorder barge with tug 

boat.

1 116.5 × 24 ft (barge); ...

23 × 15 ft (tug) .............

Seismic data recording ....................................... 24-hr operation. 

Cable boats ................... 5–6 42.6 × 13 ft ................... Deploy and retrieve receiver cables (with hydrophones/geophones).24-hr operation. 

Crew transport vessels 2 44 × 14 ft ...................... Transport crew and supplies to and from the 

working vessels.

Intermittently, minimum 

every 8 hours. 

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TABLE 1—SUMMARY OF NUMBER AND TYPE OF VESSELS INVOLVED IN THE PROPOSED SIMPSON LAGOON OBC SEISMIC

SURVEY—Continued 

[The dimensions provided are approximate] 

Vessel type Number Dimensions Main activity Frequency 

Shallow water crew and 

support boats.

2–3 34 × 10.5 ft ................... Transport 2–5 people and small amounts of 

gear for the boats operating in the shallower 

parts of the survey area.

Intermittently. 

HSSE vessel ................. 1 38 × 15 ft ...................... Support SSV measurements, HSSE (health, 

safety, security, and environmental) compliance.

As required. 

To deploy and retrieve receivers in 

water depths less than those accessible 

by the cable boats (surf-zone), 

equipment such as airboats, buggies or 

an Arktos (amphibious craft) and/or Jon 

boats may be used. Helicopters and/or 

approved tundra travel vehicles would 

be used for deployment of receiver units 

onshore as well on the barrier islands. 

In the case of helicopters being used, the 

flight altitude would be at 1,500 feet for 

3 to 6 times each day during gear 

deployment and retrieval on barrier 

islands and on shore (i.e., for about 14 

days in late July and early August for 

deployment and for about 14 days 

probably after the Cross Island hunt, 

which typically ends around 

September 10). 

Vessels and other equipment would 

be transported to the North Slope in late 

May/early June by trucks. Equipment 

would be staged at the CGGVeritas pad 

for preparation. Vessel preparation 

would include assembly of navigation 

and source equipment, cable 

deployment and retrieval systems and 

safety equipment. Once assembled, 

vessels would be launched at either 

West Dock or Milne Point. Deployment, 

retrieval, navigation and source systems 

will then be tested near West Dock or 

in the project area prior to 

commencement of operations. 

Crew Housing and Transfer 

The total number of people that 

would be involved is about 220, 

including crew on boats, camp 

personnel, mechanics, and management. 

There are no accommodations available 

on the source vessels or cable boats for 

the crew directly involved in the 

seismic operations, so crews would be 

changed out every 8 to 12 hours. Two 

vessels would be used for crew 

transfers. 

The recorder barge/boat (M/V 

Alaganik and Hook Point) may 

accommodate up to 10 people. The 

barge portion is dedicated to recording 

and staging of cables, hydrophones and 

batteries and fuelling operations. 

Refueling of vessels would be via 

other vessels at sea, and from land based 

sources located at West Dock and Milne 

Point Unit following approved U.S. 

Coast Guard procedures. Sea states and 

the vessel’s function will be the 

determining factors on which method is 

used. 

Dates, Duration and Action Area 

BP seeks an incidental harassment 

authorization for the period July 1 to 

October 15, 2012. Anticipated duration 

of seismic data acquisition is 

approximately 50 days, depending on 

weather and other circumstances. 

Transportation of vessels to West Dock 

would occur by road in late May/early 

June. It is not anticipated that vessels 

would need to transit by sea; however, 

in case this does occur the transit would 

take place when ice conditions allow 

and in consideration of the spring 

beluga and bowhead hunt in the 

Chukchi Sea. 

The project area encompasses 

110 mi 2 in Simpson Lagoon, Beaufort 

Sea, Alaska. The approximate 

boundaries of the total surface area are 

between 70°28′ N and 70°39′ N and 

between 149°24′W and 149°55′ W 

(Figure 1.2 of BP’s IHA application). 

About 46 mi 2 (41.8%) of the survey area 

is located inside the barrier islands in 

water depths of 0 to 9 ft (0 to 3 m), and 

36 mi2 (32.7%) outside the barrier 

islands in water depths of 3 to 45 ft (1 

to 15 m). The remaining 28 mi 2 (25.5%) 

of the survey area is located on land 

(onshore and barrier islands), which is 

solely being used for deployment of the 

receivers. The planned start date of 

seismic data acquisition offshore of the 

barrier islands is July 1, 2012, 

depending on the presence of ice. Open 

water seismic operations can only start 

when the project area is ice free (i.e. < 

10% ice coverage), which in this area 

normally occurs around mid-July (+/¥ 

14 days). Limited layout of receiver 

cables might be possible on land and 

barrier islands before the ice has 

cleared. To limit potential impacts to 

the bowhead whale migration and the 

subsistence hunt, no airgun operations 

would take place in the area north of the 

barrier islands after August 25, 2012. 

Surf zone geophone retrieval may 

continue for a brief period after airgun 

operations are complete. 

Description of Marine Mammals in the 

Area of the Specified Activity 

The marine mammal species under 

NMFS jurisdiction most likely to occur 

in the seismic survey area include three 

cetacean species, beluga 

(Delphinapterus leucas), bowhead 

whales (Balaena mysticetus), and gray 

whales (Eschrichtius robustus), and 

three pinniped species, ringed (Phoca 

hispida), spotted (P. largha), and 

bearded seals (Erignathus barbatus). 

Five additional cetacean species: 

Harbor porpoise (Phocoena phocoena), 

narwhal (Monodon monoceros), killer 

whale (Orcinus orca), humpback whale 

(Megaptera novaeangliae), and minke 

whale (Balaenoptera acutorostrata) 

could also occur in the project area. 

However, these cetacean species are rare 

or extralimital to the Beaufort Sea and 

less likely to be encountered in the 

Simpson Lagoon area. BP did not 

request take for narwhal as it is very 

unlikely that this species would be 

encountered during the BP’s proposed 

seismic survey. 

Ribbon seals (Histriophoca fasciata) 

occur mainly in the western part of the 

Beaufort Sea and are rare in the 

proposed action area in the Simpson 

Lagoon of the Beaufort Sea. 

The bowhead whale is listed as 

‘‘endangered’’ under the Endangered 

Species Act (ESA) and as depleted 

under the MMPA. Certain stocks or 

populations of gray and beluga whales 

and spotted seals are listed as 

endangered or proposed for listing 

under the ESA; however, none of those 

stocks or populations occur in the 

proposed activity area. Additionally, the 

ribbon seal is considered a ‘‘species of 

concern’’, meaning that NMFS has some 

concerns regarding status and threats of 

this species, but for which insufficient 

information is available to indicate a 

need to list the species under the ESA. 

Bearded and ringed seals are ‘‘candidate 

species’’ under the ESA, meaning they 

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are currently being considered for 

listing. 

The Alaska stock of bearded seals, 

part of the Beringia distinct population 

segment (DPS), has been proposed by 

NMFS for listing as threatened under 

the ESA (75 FR 77496; December 10, 

2011). 

The Alaska stock of ringed seals is not 

currently listed as endangered, and is 

not classified as a strategic stock by 

NMFS. However, there is increasing 

concern about the future of the ringed 

seal due to receding ice conditions and 

potential habitat loss. NMFS conducted 

a status review for the ringed seal (Kelly 

et al. 2010a), and has proposed to list 

the Arctic stock of ringed seals as 

threatened under the ESA due to threats 

from global warming (75 FR 77476; 

December 10, 2011). 

The final decisions for listing are 

expected to be made in summer 2012. 

BP’s application contains information 

on the status, distribution, seasonal 

distribution, and abundance of each of 

the species under NMFS jurisdiction 

mentioned in this document. Please 

refer to the application for that 

information (see ADDRESSES). Additional 

information can also be found in the 

NMFS Stock Assessment Reports (SAR). 

The Alaska 2011 SAR is available at: 

http://www.nmfs.noaa.gov/pr/pdfs/sars/ 

ak2011.pdf. 

Potential Effects of the Specified 

Activity on Marine Mammals 

Operating active acoustic sources 

such as airgun arrays, pinger systems, 

and vessel activities have the potential 

for adverse effects on marine mammals. 

Potential Effects of Airgun Sounds on 

Marine Mammals 

The effects of sounds from airgun 

pulses might include one or more of the 

following: Tolerance, masking of natural 

sounds, behavioral disturbance, and 

temporary or permanent hearing 

impairment or non-auditory effects 

(Richardson et al. 1995). As outlined in 

previous NMFS documents, the effects 

of noise on marine mammals are highly 

variable, and can be categorized as 

follows (based on Richardson et al. 

1995): 

(1) Behavioral Disturbance 

Marine mammals may behaviorally 

react to sound when exposed to 

anthropogenic noise. These behavioral 

reactions are often shown as: Changing 

durations of surfacing and dives, 

number of blows per surfacing, or 

moving direction and/or speed; 

reduced/increased vocal activities; 

changing/cessation of certain behavioral 

activities (such as socializing or 

feeding); visible startle response or 

aggressive behavior (such as tail/fluke 

slapping or jaw clapping); avoidance of 

areas where noise sources are located; 

and/or flight responses (e.g., pinnipeds 

flushing into water from haulouts or 

rookeries). 

The biological significance of many of 

these behavioral disturbances is difficult 

to predict, especially if the detected 

disturbances appear minor. However, 

the consequences of behavioral 

modification could be expected to be 

biologically significant if the change 

affects growth, survival, and 

reproduction. Some of these potential 

significant behavioral modifications 

include: 

• Drastic change in diving/surfacing 

patterns (such as those thought to be 

causing beaked whale stranding due to 

exposure to military mid-frequency 

tactical sonar); 

• Habitat abandonment due to loss of 

desirable acoustic environment; and 

• Cease feeding or social interaction. 

For example, at the Guerreo Negro 

Lagoon in Baja California, Mexico, 

which is one of the important breeding 

grounds for Pacific gray whales, 

shipping and dredging associated with a 

salt works may have induced gray 

whales to abandon the area through 

most of the 1960s (Bryant et al. 1984). 

After these activities stopped, the 

lagoon was reoccupied, first by single 

whales and later by cow-calf pairs. 

The onset of behavioral disturbance 

from anthropogenic noise depends on 

both external factors (characteristics of 

noise sources and their paths) and the 

receiving animals (hearing, motivation, 

experience, demography) and is also 

difficult to predict (Southall et al. 2007). 

Currently NMFS uses 160 dB re 1 mPa 

(rms) at received level for impulse 

noises (such as airgun pulses) as the 

threshold for the onset of marine 

mammal behavioral harassment. 

In addition, behavioral disturbance is 

also expressed as the change in vocal 

activities of animals. For example, there 

is one recent summary report indicating 

that calling fin whales distributed in 

one part of the North Atlantic went 

silent for an extended period starting 

soon after the onset of a seismic survey 

in the area (Clark and Gagnon 2006). It 

is not clear from that preliminary paper 

whether the whales ceased calling 

because of masking, or whether this was 

a behavioral response not directly 

involving masking (i.e., important 

biological signals for marine mammals 

being ‘‘masked’’ by anthropogenic noise; 

see below). Also, bowhead whales in the 

Beaufort Sea may decrease their call 

rates in response to seismic operations, 

although movement out of the area 

might also have contributed to the lower 

call detection rate (Blackwell et al. 

2009a; 2009b). Some of the changes in 

marine mammal vocal communication 

are thought to be used to compensate for 

acoustic masking resulting from 

increased anthropogenic noise (see 

below). For example, blue whales are 

found to increase call rates when 

exposed to seismic survey noise in the 

St. Lawrence Estuary (Di Iorio and Clark 

2009). The North Atlantic right whales 

(Eubalaena glacialis) exposed to high 

shipping noise increase call frequency 

(Parks et al. 2007) and intensity (Parks 

et al. 2010), while some humpback 

whales respond to low-frequency active 

sonar playbacks by increasing song 

length (Miller el al. 2000). These 

behavioral responses could also have 

adverse effects on marine mammals. 

Mysticete: Baleen whales generally 

tend to avoid operating airguns, but 

avoidance radii are quite variable. 

Whales are often reported to show no 

overt reactions to airgun pulses at 

distances beyond a few kilometers, even 

though the airgun pulses remain well 

above ambient noise levels out to much 

longer distances (reviewed in 

Richardson et al. 1995; Gordon et al. 

2004). However, studies done since the 

late 1990s of migrating humpback and 

migrating bowhead whales show 

reactions, including avoidance, that 

sometimes extend to greater distances 

than documented earlier. Therefore, it 

appears that behavioral disturbance can 

vary greatly depending on context, and 

not just received levels alone. 

Avoidance distances often exceed the 

distances at which boat-based observers 

can see whales, so observations from the 

source vessel can be biased. 

Observations over broader areas may be 

needed to determine the range of 

potential effects of some large-source 

seismic surveys where effects on 

cetaceans may extend to considerable 

distances (Richardson et al. 1999; Moore 

and Angliss 2006). Longer-range 

observations, when required, can 

sometimes be obtained via systematic 

aerial surveys or aircraft-based 

observations of behavior (e.g., 

Richardson et al. 1986, 1999; Miller et 

al. 1999, 2005; Yazvenko et al. 2007a, 

2007b) or by use of observers on one or 

more support vessels operating in 

coordination with the seismic vessel 

(e.g., Smultea et al. 2004; Johnson et al. 

2007). However, the presence of other 

vessels near the source vessel can, at 

least at times, reduce sightability of 

cetaceans from the source vessel 

(Beland et al. 2009), thus complicating 

interpretation of sighting data. 

Some baleen whales show 

considerable tolerance of seismic 

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25834 Federal Register / Vol. 77, No. 84 / Tuesday, May 1, 2012 / Notices 

pulses. However, when the pulses are 

strong enough, avoidance or other 

behavioral changes become evident. 

Because the responses become less 

obvious with diminishing received 

sound level, it has been difficult to 

determine the maximum distance (or 

minimum received sound level) at 

which reactions to seismic activity 

become evident and, hence, how many 

whales are affected. 

Studies of gray, bowhead, and 

humpback whales have determined that 

received levels of pulses in the 

160–170 dB re 1 mPa (rms) range seem 

to cause obvious avoidance behavior in 

a substantial fraction of the animals 

exposed (McCauley et al. 1998, 1999, 

2000). In many areas, seismic pulses 

diminish to these levels at distances 

ranging from 4–15 km from the source. 

A substantial proportion of the baleen 

whales within such distances may show 

avoidance or other strong disturbance 

reactions to the operating airgun array. 

Some extreme examples including 

migrating bowhead whales avoiding 

considerably larger distances 

(20–30 km) and lower received sound 

levels (120–130 dB re 1 mPa (rms)) when 

exposed to airguns from seismic 

surveys. Also, even in cases where there 

is no conspicuous avoidance or change 

in activity upon exposure to sound 

pulses from distant seismic operations, 

there are sometimes subtle changes in 

behavior (e.g., surfacing–respiration– 

dive cycles) that are only evident 

through detailed statistical analysis 

(e.g., Richardson et al. 1986; Gailey et 

al. 2007). 

Data on short-term reactions by 

cetaceans to impulsive noises are not 

necessarily indicative of long-term or 

biologically significant effects. It is not 

known whether impulsive sounds affect 

reproductive rate or distribution and 

habitat use in subsequent days or years. 

However, gray whales have continued to 

migrate annually along the west coast of 

North America despite intermittent 

seismic exploration (and much ship 

traffic) in that area for decades 

(Appendix A in Malme et al. 1984; 

Richardson et al. 1995), and there has 

been a substantial increase in the 

population over recent decades (Allen 

and Angliss 2010). 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). Similarly, 

bowhead whales have 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), 

and their numbers have increased 

notably (Allen and Angliss 2010). 

Bowheads also have been observed over 

periods of days or weeks in areas 

ensonified repeatedly by seismic pulses 

(Richardson et al. 1987; Harris et al. 

2007). However, it is generally not 

known whether the same individual 

bowheads were involved in these 

repeated observations (within and 

between years) in strongly ensonified 

areas. 

Odontocete: Little systematic 

information is available about reactions 

of toothed whales to airgun pulses. Few 

studies similar to the more extensive 

baleen whale/seismic pulse work 

summarized above have been reported 

for toothed whales. However, there are 

recent systematic data on sperm whales 

(e.g., Gordon et al. 2006; Madsen et al. 

2006; Winsor and Mate 2006; Jochens et 

al. 2008; Miller et al. 2009). There is 

also 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; Holst et al. 2006; Stone and 

Tasker 2006; Potter et al. 2007; Hauser 

et al. 2008; Holst and Smultea 2008; 

Weir 2008; Barkaszi et al. 2009; 

Richardson et al. 2009). 

Dolphins and porpoises are often seen 

by observers on active seismic vessels, 

occasionally at close distances (e.g., bow 

riding). Marine mammal monitoring 

data during seismic surveys often show 

that animal detection rates drop during 

the firing of seismic airguns, indicating 

that animals may be avoiding the 

vicinity of the seismic area (Smultea et 

al. 2004; Holst et al. 2006; Hauser et al. 

2008; Holst and Smultea 2008; 

Richardson et al. 2009). Also, belugas 

summering in the Canadian Beaufort 

Sea showed larger-scale avoidance, 

tending to avoid waters out to 

10–20 km from operating seismic 

vessels. In contrast, recent studies show 

little evidence of conspicuous reactions 

by sperm whales to airgun pulses, 

contrary to earlier indications (e.g., 

Gordon et al. 2006; Stone and Tasker 

2006; Winsor and Mate 2006; Jochens et 

al. 2008), except the lower buzz 

(echolocation signals) rates that were 

detected during exposure of airgun 

pulses (Miller et al. 2009). 

There are almost no specific data on 

responses of beaked whales to seismic 

surveys, but it is likely that most if not 

all species show strong avoidance. 

There is increasing evidence that some 

beaked whales may strand after 

exposure to strong noise from tactical 

military mid-frequency sonars. Whether 

they ever do so in response to seismic 

survey noise is unknown. Northern 

bottlenose whales seem to continue to 

call when exposed to pulses from 

distant seismic vessels. 

For delphinids, and possibly the 

Dall’s porpoise, the available data 

suggest that a ≥170 dB re 1 mPa (rms) 

disturbance criterion (rather than ≥160 

dB) would be appropriate. With a 

medium-to-large airgun array, received 

levels typically diminish to 170 dB 

within 1–4 km, whereas levels typically 

remain above 160 dB out to 4—15 km 

(e.g., Tolstoy et al. 2009). Reaction 

distances for delphinids are more 

consistent with the typical 170 dB re 1 

mPa (rms) distances. Stone (2003) and 

Stone and Tasker (2006) reported that 

all small odontocetes (including killer 

whales) observed during seismic 

surveys in UK waters remained 

significantly further from the source 

during periods of shooting on surveys 

with large volume airgun arrays than 

during periods without airgun shooting. 

Due to their relatively higher 

frequency hearing ranges when 

compared to mysticetes, odontocetes 

may have stronger responses to midand high-frequency sources such as subbottom profilers, side scan sonar, and 

echo sounders than mysticetes 

(Richardson et al. 1995; Southall et al. 

2007). 

Pinnipeds: Few studies of the 

reactions of pinnipeds to noise from 

open-water seismic exploration have 

been published (for review of the early 

literature, see Richardson et al. 1995). 

However, pinnipeds have been observed 

during a number of seismic monitoring 

studies. Monitoring in the Beaufort Sea 

during 1996–2002 provided a 

substantial amount of information on 

avoidance responses (or lack thereof) 

and associated behavior. Additional 

monitoring of that type has been done 

in the Beaufort and Chukchi Seas in 

2006–2009. Pinnipeds exposed to 

seismic surveys have also been observed 

during seismic surveys along the U.S. 

west coast. Also, there are data on the 

reactions of pinnipeds to various other 

related types of impulsive sounds. 

Early observations provided 

considerable evidence that pinnipeds 

are often quite tolerant of strong pulsed 

sounds. During seismic exploration off 

Nova Scotia, gray seals exposed to noise 

from airguns and linear explosive 

charges reportedly did not react strongly 

(J. Parsons in Greene et al. 1985). An 

airgun caused an initial startle reaction 

among South African fur seals but was 

ineffective in scaring them away from 

fishing gear. Pinnipeds in both water 

and air sometimes tolerate strong noise 

pulses from non-explosive and 

explosive scaring devices, especially if 

attracted to the area for feeding or 

reproduction (Mate and Harvey 1987; 

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Reeves et al. 1996). Thus, pinnipeds are 

expected to be rather tolerant of, or to 

habituate to, repeated underwater 

sounds from distant seismic sources, at 

least when the animals are strongly 

attracted to the area. 

In summary, visual monitoring from 

seismic vessels has shown only slight (if 

any) avoidance of airguns by pinnipeds, 

and only slight (if any) changes in 

behavior. These studies show that many 

pinnipeds do not avoid the area within 

a few hundred meters of an operating 

airgun array. However, based on the 

studies with large sample size, or 

observations from a separate monitoring 

vessel, or radio telemetry, it is apparent 

that some phocid seals do show 

localized avoidance of operating 

airguns. The limited nature of this 

tendency for avoidance is a concern. It 

suggests that one cannot rely on 

pinnipeds to move away, or to move 

very far away, before received levels of 

sound from an approaching seismic 

survey vessel approach those that may 

cause hearing impairment. 

(2) Masking 

Chronic exposure to excessive, though 

not high-intensity, noise could cause 

masking at particular frequencies for 

marine mammals that utilize sound for 

vital biological functions. Masking can 

interfere with detection of acoustic 

signals such as communication calls, 

echolocation sounds, and 

environmental sounds important to 

marine mammals. Since marine 

mammals depend on acoustic cues for 

vital biological functions, such as 

orientation, communication, finding 

prey, and avoiding predators, marine 

mammals that experience severe 

(intensity and duration) acoustic 

masking could potentially suffer 

reduced fitness, which could lead to 

adverse effects on survival and 

reproduction. 

Masking occurs when noise and 

signals (that animal utilizes) overlap at 

both spectral and temporal scales. For 

the airgun noise generated from the 

proposed marine seismic survey, these 

are low frequency (under 1 kHz) pulses 

with extremely short durations (in the 

scale of milliseconds). Lower frequency 

man-made noises are more likely to 

affect detection of communication calls 

and other potentially important natural 

sounds such as surf and prey noise. 

There is little concern regarding 

masking due to the brief duration of 

these pulses and relatively longer 

silence between airgun shots (9–12 

seconds) near the noise source, 

however, at long distances (over tens of 

kilometers away) in deep water, due to 

multipath propagation and 

reverberation, the durations of airgun 

pulses can be ‘‘stretched’’ to seconds 

with long decays (Madsen et al. 2006; 

Clark and Gagnon 2006). Therefore it 

could affect communication signals 

used by low frequency mysticetes when 

they occur near the noise band and thus 

reduce the communication space of 

animals (e.g., Clark et al. 2009a, 2009b) 

and affect their vocal behavior (e.g., 

Foote et al. 2004; Holt et al. 2009). 

Further, in areas of shallow water, 

multipath propagation of airgun pulses 

could be more profound, thus affecting 

communication signals from marine 

mammals even at close distances. 

Average ambient noise in areas where 

received seismic noises are heard can be 

elevated. At long distances, however, 

the intensity of the noise is greatly 

reduced. Nevertheless, partial 

informational and energetic masking of 

different degrees could affect signal 

receiving in some marine mammals 

within the ensonified areas. Additional 

research is needed to further address 

these effects. 

Although masking effects of pulsed 

sounds on marine mammal calls and 

other natural sounds are expected to be 

limited, there are few specific studies on 

this. Some whales continue calling in 

the presence of seismic pulses and 

whale calls often can be heard between 

the seismic pulses (e.g., Richardson et 

al. 1986; McDonald et al. 1995; Greene 

et al. 1999a, 1999b; Nieukirk et al. 2004; 

Smultea et al. 2004; Holst et al. 2005a, 

2005b, 2006; Dunn and Hernandez 

2009). 

Among the odontocetes, there has 

been one report that sperm whales 

ceased calling when exposed to pulses 

from a very distant seismic ship (Bowles 

et al. 1994). However, more recent 

studies of sperm whales found that they 

continued calling in the presence of 

seismic pulses (Madsen et al. 2002; 

Tyack et al. 2003; Smultea et al. 2004; 

Holst et al. 2006; Jochens et al. 2008). 

Madsen et al. (2006) noted that airgun 

sounds would not be expected to mask 

sperm whale calls given the intermittent 

nature of airgun pulses. Dolphins and 

porpoises are also commonly heard 

calling while airguns are operating 

(Gordon et al. 2004; Smultea et al. 2004; 

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

2007). Masking effects of seismic pulses 

are expected to be negligible in the case 

of the smaller odontocetes, given the 

intermittent nature of seismic pulses 

plus the fact that sounds important to 

them are predominantly at much higher 

frequencies than are the dominant 

components of airgun sounds. 

Pinnipeds have best hearing 

sensitivity and/or produce most of their 

sounds at frequencies higher than the 

dominant components of airgun sound, 

but there is some overlap in the 

frequencies of the airgun pulses and the 

calls. However, the intermittent nature 

of airgun pulses presumably reduces the 

potential for masking. 

Marine mammals are thought to be 

able to compensate for masking by 

adjusting their acoustic behavior such as 

shifting call frequencies, and increasing 

call volume and vocalization rates, as 

discussed earlier (e.g., Miller et al. 2000; 

Parks et al. 2007; Di Iorio and Clark 

2009; Parks et al. 2010); the biological 

significance of these modifications is 

still unknown. 

(3) Hearing Impairment 

Marine mammals exposed to high 

intensity sound repeatedly or for 

prolonged periods can experience 

hearing threshold shift (TS), which is 

the loss of hearing sensitivity at certain 

frequency ranges (Kastak et al. 1999; 

Schlundt et al. 2000; Finneran et al. 

2002; 2005). TS can be permanent 

(PTS), in which case the loss of hearing 

sensitivity is unrecoverable, or 

temporary (TTS), in which case the 

animal’s hearing threshold will recover 

over time (Southall et al. 2007). Marine 

mammals that experience TTS or PTS 

will have reduced sensitivity at the 

frequency band of the TS, which may 

affect their capability of 

communication, orientation, or prey 

detection. The degree of TS depends on 

the intensity of the received levels the 

animal is exposed to, and the frequency 

at which TS occurs depends on the 

frequency of the received noise. It has 

been shown that in most cases, TS 

occurs at the frequencies approximately 

one-octave above that of the received 

noise. Repeated noise exposure that 

leads to TTS could cause PTS. For 

transient sounds, the sound level 

necessary to cause TTS is inversely 

related to the duration of the sound. 

TTS 

TTS is the mildest form of hearing 

impairment that can occur during 

exposure to a strong sound (Kryter 

1985). While experiencing TTS, the 

hearing threshold rises and a sound 

must be stronger in order to be heard. 

It is a temporary phenomenon, and 

(especially when mild) is not 

considered to represent physical 

damage or ‘‘injury’’ (Southall et al. 

2007). Rather, the onset of TTS is an 

indicator that, if the animal is exposed 

to higher levels of that sound, physical 

damage is ultimately a possibility. 

The magnitude of TTS depends on the 

level and duration of noise exposure, 

and to some degree on frequency, 

among other considerations (Kryter 

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1985; Richardson et al. 1995; Southall et 

al. 2007). For sound exposures at or 

somewhat above the TTS threshold, 

hearing sensitivity recovers rapidly after 

exposure to the noise ends. In terrestrial 

mammals, TTS can last from minutes or 

hours to (in cases of strong TTS) days. 

Only a few data have been obtained on 

sound levels and durations necessary to 

elicit mild TTS in marine mammals 

(none in mysticetes), and none of the 

published data concern TTS elicited by 

exposure to multiple pulses of sound 

during operational seismic surveys 

(Southall et al. 2007). 

For toothed whales, experiments on a 

bottlenose dolphin (Tursiops truncates) 

and beluga whale showed that exposure 

to a single watergun impulse at a 

received level of 207 kPa (or 30 psi) 

peak-to-peak (p-p), which is equivalent 

to 228 dB re 1 mPa (p-p), resulted in a 

7 and 6 dB TTS in the beluga whale at 

0.4 and 30 kHz, respectively. 

Thresholds returned to within 2 dB of 

the pre-exposure level within 4 minutes 

of the exposure (Finneran et al. 2002). 

No TTS was observed in the bottlenose 

dolphin. 

Finneran et al. (2005) further 

examined the effects of tone duration on 

TTS in bottlenose dolphins. Bottlenose 

dolphins were exposed to 3 kHz tones 

(non-impulsive) for periods of 1, 2, 4 or 

8 seconds (s), with hearing tested at 4.5 

kHz. For 1-s exposures, TTS occurred 

with SELs of 197 dB, and for exposures 

>1 s, SEL >195 dB resulted in TTS (SEL 

is equivalent to energy flux, in dB re 1 

mPa2-s). At an SEL of 195 dB, the mean 

TTS (4 min after exposure) was 2.8 dB. 

Finneran et al. (2005) suggested that an 

SEL of 195 dB is the likely threshold for 

the onset of TTS in dolphins and 

belugas exposed to tones of durations 

1–8 s (i.e., TTS onset occurs at a nearconstant SEL, independent of exposure 

duration). That implies that, at least for 

non-impulsive tones, a doubling of 

exposure time results in a 3 dB lower 

TTS threshold. 

However, the assumption that, in 

marine mammals, the occurrence and 

magnitude of TTS is a function of 

cumulative acoustic energy (SEL) is 

probably an oversimplification. Kastak 

et al. (2005) reported preliminary 

evidence from pinnipeds that, for 

prolonged non-impulse noise, higher 

SELs were required to elicit a given TTS 

if exposure duration was short than if it 

was longer, i.e., the results were not 

fully consistent with an equal-energy 

model to predict TTS onset. Mooney et 

al. (2009a) showed this in a bottlenose 

dolphin exposed to octave-band nonimpulse noise ranging from 4 to 8 kHz 

at SPLs of 130 to 178 dB re 1 mPa for 

periods of 1.88 to 30 minutes (min). 

Higher SELs were required to induce a 

given TTS if exposure duration was 

short than if it was longer. Exposure of 

the aforementioned bottlenose dolphin 

to a sequence of brief sonar signals 

showed that, with those brief (but nonimpulse) sounds, the received energy 

(SEL) necessary to elicit TTS was higher 

than was the case with exposure to the 

more prolonged octave-band noise 

(Mooney et al. 2009b). Those authors 

concluded that, when using (nonimpulse) acoustic signals of duration 

∼0.5 s, SEL must be at least 210–214 dB 

re 1 mPa2-s to induce TTS in the 

bottlenose dolphin. The most recent 

studies conducted by Finneran et al. 

also support the notion that exposure 

duration has a more significant 

influence compared to SPL as the 

duration increases, and that TTS growth 

data are better represented as functions 

of SPL and duration rather than SEL 

alone (Finneran et al. 2010a, 2010b). In 

addition, Finneran et al. (2010b) 

conclude that when animals are 

exposed to intermittent noises, there is 

recovery of hearing during the quiet 

intervals between exposures through the 

accumulation of TTS across multiple 

exposures. Such findings suggest that 

when exposed to multiple seismic 

pulses, partial hearing recovery also 

occurs during the seismic pulse 

intervals. 

For baleen whales, there are no data, 

direct or indirect, on levels or properties 

of sound that are required to induce 

TTS. The frequencies to which baleen 

whales are most sensitive are lower than 

those to which odontocetes are most 

sensitive, and natural ambient noise 

levels at those low frequencies tend to 

be higher (Urick 1983). 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. 

However, no cases of TTS are expected 

given the small size of the airguns 

proposed to be used and the strong 

likelihood that baleen whales 

(especially migrating bowheads) would 

avoid the approaching airguns (or 

vessel) before being exposed to levels 

high enough for there to be any 

possibility of TTS. 

In pinnipeds, TTS thresholds 

associated with exposure to brief pulses 

(single or multiple) of underwater sound 

have not been measured. Initial 

evidence from prolonged 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). However, more recent 

indications are that TTS onset in the 

most sensitive pinniped species studied 

(harbor seal, which is closely related to 

the ringed seal) may occur at a similar 

SEL as in odontocetes (Kastak et al. 

2004). 

Most cetaceans show some degree of 

avoidance of seismic vessels operating 

an airgun array (see above). It is unlikely 

that these 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. TTS would be more 

likely in any odontocetes that bow- or 

wake-ride or otherwise linger near the 

airguns. However, while bow- or wakeriding, odontocetes would be at the 

surface and thus not exposed to strong 

sound pulses given the pressure release 

and Lloyd Mirror effects at the surface. 

But if bow- or wake-riding animals were 

to dive intermittently near airguns, they 

would be exposed to strong sound 

pulses, possibly repeatedly. 

If some cetaceans did incur mild or 

moderate TTS through exposure to 

airgun sounds in this manner, this 

would very likely be a temporary and 

reversible phenomenon. However, even 

a temporary reduction in hearing 

sensitivity could be deleterious in the 

event that, during that period of reduced 

sensitivity, a marine mammal needed its 

full hearing sensitivity to detect 

approaching predators, or for some 

other reason. 

Some pinnipeds show avoidance 

reactions to airguns, but their avoidance 

reactions are generally not as strong or 

consistent as those of cetaceans. 

Pinnipeds occasionally seem to be 

attracted to operating seismic vessels. 

There are no specific data on TTS 

thresholds of pinnipeds exposed to 

single or multiple low-frequency pulses. 

However, given the indirect indications 

of a lower TTS threshold for the harbor 

seal than for odontocetes exposed to 

impulse sound (see above), it is possible 

that some pinnipeds close to a large 

airgun array could incur TTS. 

NMFS currently typically includes 

mitigation requirements to ensure that 

cetaceans and pinnipeds are not 

exposed to pulsed underwater noise at 

received levels exceeding, respectively, 

180 and 190 dB re 1 mPa (rms). The 180/ 

190 dB acoustic criteria were taken from 

recommendations by an expert panel of 

the High Energy Seismic Survey (HESS) 

Team that performed an assessment on 

noise impacts by seismic airguns to 

marine mammals in 1997, although the 

HESS Team recommended a 180-dB 

limit for pinnipeds in California (HESS 

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1999). The 180 and 190 dB re 1 mPa 

(rms) levels have not been considered to 

be the levels above which TTS might 

occur. Rather, they were the received 

levels above which, in the view of a 

panel of bioacoustics specialists 

convened by NMFS before TTS 

measurements for marine mammals 

started to become available, one could 

not be certain that there would be no 

injurious effects, auditory or otherwise, 

to marine mammals. As summarized 

above, data that are now available imply 

that TTS is unlikely to occur in various 

odontocetes (and probably mysticetes as 

well) unless they are exposed to a 

sequence of several airgun pulses 

stronger than 190 dB re 1 mPa (rms). On 

the other hand, for the harbor seal, 

harbor porpoise, and perhaps some 

other species, TTS may occur upon 

exposure to one or more airgun pulses 

whose received level equals the NMFS 

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

mPa (rms). That criterion corresponds to 

a single-pulse SEL of 175–180 dB re 1 

mPa2-s in typical conditions, whereas 

TTS is suspected to be possible in 

harbor seals and harbor porpoises with 

a cumulative SEL of ∼171 and ∼164 dB 

re 1 mPa2-s, respectively. 

It has been shown that most large 

whales and many smaller odontocetes 

(especially the harbor porpoise) show at 

least localized avoidance of ships and/ 

or seismic operations. Even when 

avoidance is limited to the area within 

a few hundred meters of an airgun array, 

that should usually be sufficient to 

avoid TTS based on what is currently 

known about thresholds for TTS onset 

in cetaceans. In addition, ramping up 

airgun arrays, which is standard 

operational protocol for many seismic 

operators, may allow cetaceans near the 

airguns at the time of startup (if the 

sounds are aversive) to move away from 

the seismic source and to avoid being 

exposed to the full acoustic output of 

the airgun array. Thus, most baleen 

whales likely will not be exposed to 

high levels of airgun sounds provided 

the ramp- up procedure is applied. 

Likewise, many odontocetes close to the 

trackline are likely to move away before 

the sounds from an approaching seismic 

vessel become sufficiently strong for 

there to be any potential for TTS or 

other hearing impairment. Hence, there 

is little potential for baleen whales or 

odontocetes that show avoidance of 

ships or airguns to be close enough to 

an airgun array to experience TTS. 

Nevertheless, even if marine mammals 

were to experience TTS, the magnitude 

of the TTS is expected to be mild and 

brief, only in a few decibels for minutes. 

PTS 

When PTS occurs, there is physical 

damage to the sound receptors in the 

ear. In some cases, there can be total or 

partial deafness, whereas in other cases, 

the animal has an impaired ability to 

hear sounds in specific frequency ranges 

(Kryter 1985). Physical damage to a 

mammal’s hearing apparatus can occur 

if it is exposed to sound impulses that 

have very high peak pressures, 

especially if they have very short rise 

times. (Rise time is the interval required 

for sound pressure to increase from the 

baseline pressure to peak pressure.) 

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 likelihood that some mammals 

close to an airgun array might incur at 

least mild TTS (see above), there has 

been further speculation about the 

possibility that some individuals 

occurring very close to airguns might 

incur PTS (e.g., Richardson et al. 1995; 

Gedamke et al. 2008). Single or 

occasional occurrences of mild TTS are 

not indicative of permanent auditory 

damage, but repeated or (in some cases) 

single exposures to a level well above 

that causing TTS onset might elicit PTS. 

Relationships between TTS and PTS 

thresholds have not been studied in 

marine mammals, but are assumed to be 

similar to those in humans and other 

terrestrial mammals (Southall et al. 

2007). Based on data from terrestrial 

mammals, a precautionary assumption 

is that the PTS threshold for impulse 

sounds (such as airgun pulses as 

received close to the source) is at least 

6 dB higher than the TTS threshold on 

a peak-pressure basis, and probably >6 

dB higher (Southall et al. 2007). The 

low-to-moderate levels of TTS that have 

been induced in captive odontocetes 

and pinnipeds during controlled studies 

of TTS have been confirmed to be 

temporary, with no measurable residual 

PTS (Kastak et al. 1999; Schlundt et al. 

2000; Finneran et al. 2002; 2005; 

Nachtigall et al. 2003; 2004). However, 

very prolonged exposure to sound 

strong enough to elicit TTS, or shorterterm exposure to sound levels well 

above the TTS threshold, can cause 

PTS, at least in terrestrial mammals 

(Kryter 1985). In terrestrial mammals, 

the received sound level from a single 

non-impulsive sound exposure must be 

far above the TTS threshold for any risk 

of permanent hearing damage (Kryter 

1994; Richardson et al. 1995; Southall et 

al. 2007). However, there is special 

concern about strong sounds whose 

pulses have very rapid rise times. In 

terrestrial mammals, there are situations 

when pulses with rapid rise times (e.g., 

from explosions) can result in PTS even 

though their peak levels are only a few 

dB higher than the level causing slight 

TTS. The rise time of airgun pulses is 

fast, but not as fast as that of an 

explosion. 

Some factors that contribute to onset 

of PTS, at least in terrestrial mammals, 

are as follows: 

• Exposure to a single very intense 

sound, 

• Fast rise time from baseline to peak 

pressure, 

• Repetitive exposure to intense 

sounds that individually cause TTS but 

not PTS, and 

• Recurrent ear infections or (in 

captive animals) exposure to certain 

drugs. 

Cavanagh (2000) reviewed the 

thresholds used to define TTS and PTS. 

Based on this review and SACLANT 

(1998), it is reasonable to assume that 

PTS might occur at a received sound 

level 20 dB or more above that inducing 

mild TTS. However, for PTS to occur at 

a received level only 20 dB above the 

TTS threshold, the animal probably 

would have to be exposed to a strong 

sound for an extended period, or to a 

strong sound with a rather rapid rise 

time. 

More recently, Southall et al. (2007) 

estimated that received levels would 

need to exceed the TTS threshold by at 

least 15 dB, on an SEL basis, for there 

to be risk of PTS. Thus, for cetaceans 

exposed to a sequence of sound pulses, 

they estimate that the PTS threshold 

might be an M-weighted SEL (for the 

sequence of received pulses) of ∼198 dB 

re 1 mPa2-s. Additional assumptions had 

to be made to derive a corresponding 

estimate for pinnipeds, as the only 

available data on TTS-thresholds in 

pinnipeds pertained to nonimpulse 

sound (see above). Southall et al. (2007) 

estimated that the PTS threshold could 

be a cumulative SEL of ∼186 dB re 1 

mPa2-s in the case of a harbor seal 

exposed to impulse sound. The PTS 

threshold for the California sea lion and 

northern elephant seal would probably 

be higher given the higher TTS 

thresholds in those species. Southall et 

al. (2007) also note that, regardless of 

the SEL, there is concern about the 

possibility of PTS if a cetacean or 

pinniped received one or more pulses 

with peak pressure exceeding 230 or 

218 dB re 1 mPa, respectively. Thus, PTS 

might be expected upon exposure of 

cetaceans to either SEL ≥198 dB re 1 

mPa2-s or peak pressure ≥230 dB re 1 

mPa. Corresponding proposed dual 

criteria for pinnipeds (at least harbor 

seals) are ≥186 dB SEL and ≥ 218 dB 

peak pressure (Southall et al. 2007). 

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These estimates are all first 

approximations, given the limited 

underlying data, assumptions, species 

differences, and evidence that the 

‘‘equal energy’’ model may not be 

entirely correct. 

Sound impulse duration, peak 

amplitude, rise time, number of pulses, 

and inter-pulse interval are the main 

factors thought to determine the onset 

and extent of PTS. Ketten (1994) has 

noted that the criteria for differentiating 

the sound pressure levels that result in 

PTS (or TTS) are location and species 

specific. PTS effects may also be 

influenced strongly by the health of the 

receiver’s ear. 

As described above for TTS, in 

estimating the amount of sound energy 

required to elicit the onset of TTS (and 

PTS), it is assumed that the auditory 

effect of a given cumulative SEL from a 

series of pulses is the same as if that 

amount of sound energy were received 

as a single strong sound. There are no 

data from marine mammals concerning 

the occurrence or magnitude of a 

potential partial recovery effect between 

pulses. In deriving the estimates of PTS 

(and TTS) thresholds quoted here, 

Southall et al. (2007) made the 

precautionary assumption that no 

recovery would occur between pulses. 

It is unlikely that an odontocete 

would remain close enough to a large 

airgun array for sufficiently long to 

incur PTS. There is some concern about 

bowriding odontocetes, but for animals 

at or near the surface, auditory effects 

are reduced by Lloyd’s mirror and 

surface release effects. The presence of 

the vessel between the airgun array and 

bow-riding odontocetes could also, in 

some but probably not all cases, reduce 

the levels received by bow-riding 

animals (e.g., Gabriele and Kipple 2009). 

The TTS (and thus PTS) thresholds of 

baleen whales are unknown but, as an 

interim measure, assumed to be no 

lower than those of odontocetes. Also, 

baleen whales generally avoid the 

immediate area around operating 

seismic vessels, so it is unlikely that a 

baleen whale could incur PTS from 

exposure to airgun pulses. The TTS (and 

thus PTS) thresholds of some pinnipeds 

(e.g., harbor seal) as well as the harbor 

porpoise may be lower (Kastak et al. 

2005; Southall et al. 2007; Lucke et al. 

2009). If so, TTS and potentially PTS 

may extend to a somewhat greater 

distance for those animals. Again, 

Lloyd’s mirror and surface release 

effects will ameliorate the effects for 

animals at or near the surface. 

(4) Non-Auditory Physical Effects 

Non-auditory physical effects might 

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 

neurological effects, bubble formation, 

and other types of organ or tissue 

damage. Some marine mammal species 

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

susceptible to injury and/or stranding 

when exposed to intense sounds. 

However, there is no definitive evidence 

that any of these effects occur even for 

marine mammals in close proximity to 

large arrays of airguns, and beaked 

whales do not occur in the proposed 

project area. In addition, marine 

mammals that show behavioral 

avoidance of seismic vessels, including 

most baleen whales, some odontocetes 

(including belugas), and some 

pinnipeds, are especially unlikely to 

incur non- auditory impairment or other 

physical effects. 

Therefore, it is unlikely that such 

effects would occur during BPXA’s 

proposed surveys given the brief 

duration of exposure and the planned 

monitoring and mitigation measures 

described later in this document. 

Additional non-auditory effects 

include elevated levels of stress 

response (Wright et al. 2007; Wright and 

Highfill 2007). Although not many 

studies have been done on noiseinduced stress in marine mammals, 

extrapolation of information regarding 

stress responses in other species seems 

applicable because the responses are 

highly consistent among all species in 

which they have been examined to date 

(Wright et al. 2007). Therefore, it is 

reasonable to conclude that noise acts as 

a stressor to marine mammals. 

Furthermore, given that marine 

mammals will likely respond in a 

manner consistent with other species 

studied, repeated and prolonged 

exposures to stressors (including or 

induced by noise) could potentially be 

problematic for marine mammals of all 

ages. Wright et al. (2007) state that a 

range of issues may arise from an 

extended stress response including, but 

not limited to, suppression of 

reproduction (physiologically and 

behaviorally), accelerated aging and 

sickness-like symptoms. However, as 

mentioned above, BPXA’s proposed 

activity is not expected to result in these 

severe effects due to the nature of the 

potential sound exposure. 

(5) Stranding and Mortality 

Marine mammals close to underwater 

detonations can be killed or severely 

injured, and the auditory organs are 

especially susceptible to injury (Ketten 

et al. 1993; Ketten 1995). Airgun pulses 

are less energetic and their peak 

amplitudes have slower rise times, 

while stranding and mortality events 

would include other energy sources 

(acoustical or shock wave) far beyond 

just seismic airguns. To date, there is no 

evidence that serious injury, death, or 

stranding by marine mammals can occur 

from exposure to airgun pulses, even in 

the case of large airgun arrays. 

However, in numerous past IHA 

notices for seismic surveys, commenters 

have referenced two stranding events 

allegedly associated with seismic 

activities, one off Baja California and a 

second off Brazil. NMFS has addressed 

this concern several times, and, without 

new information, does not believe that 

this issue warrants further discussion. 

For information relevant to strandings of 

marine mammals, readers are 

encouraged to review NMFS’ response 

to comments on this matter found in 69 

FR 74906 (December 14, 2004), 71 FR 

43112 (July 31, 2006), 71 FR 50027 

(August 24, 2006), and 71 FR 49418 

(August 23, 2006). 

It should be noted that strandings 

related to sound exposure have not been 

recorded for marine mammal species in 

the Beaufort Sea. NMFS notes that in 

the Beaufort Sea, aerial surveys have 

been conducted by MMS and industry 

during periods of industrial activity 

(and by MMS during times with no 

activity). No strandings or marine 

mammals in distress have been 

observed during these surveys and none 

have been reported by North Slope 

Borough inhabitants. In addition, there 

are very few instances that seismic 

surveys in general have been linked to 

marine mammal strandings, other than 

those mentioned above. As a result, 

NMFS does not expect any marine 

mammals will incur serious injury or 

mortality in the Arctic Ocean or strand 

as a result of the proposed seismic 

survey. 

Potential Effects of Pinger Signals 

A pinger system (Sonardyne 

Acoustical Pingers) and acoustic 

releases/transponders would be used 

during seismic operations to position 

the receivers and locate and retrieve the 

batteries. Sounds transmitted by these 

pingers are characterized by very short 

pulses. The Sonardyne pinger has a 

source level ranging from ∼188–193 dB 

re 1 mPa at 1 m in a frequency range of 

19–36 kHz and the transponder has 

source levels ∼192 dB re 1 mPa at 1 m 

in a frequency range of 7–15 kHz. Pulses 

are emitted on command from the 

operator aboard the source vessel. 

The pinger produces sounds within 

the frequency range that could be 

detected by some seals (functional 

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underwater hearing estimated at 75 Hz 

to 75 kHz), baleen whales (hearing 

sensitivity from few tens of Hz to ∼10 

kHz), and beluga whales (peak 

sensitivity at ∼10–15 kHz) (Southall et 

al. 2007). However, marine mammal 

communications will not be masked 

appreciably by the pinger signals 

because of the relatively low power 

output, low duty cycle, and brief period 

when an individual mammal is likely to 

be within the area where they could 

potentially be exposed. 

Marine mammal behavioral reactions 

to pulsed sound sources such as airguns 

are discussed above, and responses to 

pinger sounds are likely similar if 

received at the same levels. However, 

the pulsed signals from the pinger are 

much weaker than those from the airgun 

and will propagate over shorter 

distances. Therefore, behavioral 

responses are not expected unless 

marine mammals are very close (within 

tens of meters) to the source. The 

maximum reaction that might be 

expected would be a startle reaction or 

other short-term response. 

Source levels of the pinger are much 

lower than those of the airguns, which 

are discussed above. It is unlikely that 

the pinger produces pulse levels strong 

enough to cause temporary hearing 

impairment or (especially) physical 

injuries even in an animal that is 

(briefly) in a position near the source. 

Vessel Sounds 

In addition to the noise generated 

from seismic airguns, various types of 

vessels will be used in the operations, 

including source vessels, recorder/cable 

vessels, and various support vessels. 

Sounds from boats and vessels have 

been reported extensively (Greene and 

Moore 1995; Blackwell and Greene 

2002; 2005; 2006). Numerous 

measurements of underwater vessel 

sound have been performed in support 

of recent industry activity in the 

Chukchi and Beaufort Seas. Results of 

these measurements have been reported 

in various 90-day and comprehensive 

reports since 2007 (e.g., Aerts et al. 

2008; Hauser et al. 2008; Brueggeman 

2009; Ireland et al. 2009; Hartin et al. 

2011). For example, Garner and Hannay 

(2009) estimated sound pressure levels 

of 100 dB at distances ranging from 

approximately 1.5 to 2.3 mi (2.4 to 3.7 

km) from various types of barges. 

MacDonald et al. (2008) estimated 

higher underwater SPLs from the 

seismic vessel Gilavar of 120 dB at 

approximately 13 mi (21 km) from the 

source, although the sound level was 

only 150 dB at 85 ft (26 m) from the 

vessel. Compared to airgun pulses, 

underwater sound from vessels is 

generally at relatively low frequencies. 

The primary sources of sounds from 

all vessel classes are propeller 

cavitation, propeller singing, and 

propulsion or other machinery. 

Propeller cavitation is usually the 

dominant noise source for vessels (Ross 

1976). Propeller cavitation and singing 

are produced outside the hull, whereas 

propulsion or other machinery noise 

originates inside the hull. There are 

additional sounds produced by vessel 

activity, such as pumps, generators, 

flow noise from water passing over the 

hull, and bubbles breaking in the wake. 

Anticipated Effects on Habitat 

The primary potential impacts to 

marine mammals and other marine 

species are associated with elevated 

sound levels produced by airguns and 

vessels operating in the area. However, 

other potential impacts to the 

surrounding habitat from physical 

disturbance are also possible. 

Potential Impacts on Prey Species 

With regard to fish as a prey source 

for cetaceans and pinnipeds, fish are 

known to hear and react to sounds and 

to use sound to communicate (Tavolga 

et al. 1981) and possibly avoid predators 

(Wilson and Dill 2002). Experiments 

have shown that fish can sense both the 

strength and direction of sound 

(Hawkins 1981). Primary factors 

determining whether a fish can sense a 

sound signal, and potentially react to it, 

are the frequency of the signal and the 

strength of the signal in relation to the 

natural background noise level. 

The level of sound at which a fish 

will react or alter its behavior is usually 

well above the detection level. Fish 

have been found to react to sounds 

when the sound level increased to about 

20 dB above the detection level of 120 

dB (Ona 1988); however, the response 

threshold can depend on the time of 

year and the fish’s physiological 

condition (Engas et al. 1993). In general, 

fish react more strongly to pulses of 

sound rather than non-pulse signals 

(such as noise from vessels) (Blaxter et 

al. 1981), and a quicker alarm response 

is elicited when the sound signal 

intensity rises rapidly compared to 

sound rising more slowly to the same 

level. 

Investigations of fish behavior in 

relation to vessel noise (Olsen et al. 

1983; Ona 1988; Ona and Godo 1990) 

have shown that fish react when the 

sound from the engines and propeller 

exceeds a certain level. Avoidance 

reactions have been observed in fish 

such as cod and herring when vessels 

approached close enough that received 

sound levels are 110 dB to 130 dB 

(Nakken 1992; Olsen 1979; Ona and 

Godo 1990; Ona and Toresen 1988). 

However, other researchers have found 

that fish such as polar cod, herring, and 

capeline are often attracted to vessels 

(apparently by the noise) and swim 

toward the vessel (Rostad et al. 2006). 

Typical sound source levels of vessel 

noise in the audible range for fish are 

150 dB to 170 dB (Richardson et al. 

1995). 

Further, during the seismic survey 

only a small fraction of the available 

habitat would be ensonified at any given 

time. Disturbance to fish species would 

be short-term and fish would return to 

their pre-disturbance behavior once the 

seismic activity ceases (McCauley et al. 

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

Pearson et al. 1992). Thus, the proposed 

survey would have little, if any, impact 

on the abilities of marine mammals to 

feed in the area where seismic work is 

planned. 

Some mysticetes, including bowhead 

whales, feed on concentrations of 

zooplankton. Some feeding bowhead 

whales may occur in the Alaskan 

Beaufort Sea in July and August, and 

others feed intermittently during their 

westward migration in September and 

October (Richardson and Thomson 

[eds.] 2002; Lowry et al. 2004). A 

reaction by zooplankton to a seismic 

impulse would only be relevant to 

whales if it caused concentrations of 

zooplankton to scatter. Pressure changes 

of sufficient magnitude to cause that 

type of reaction would probably occur 

only very close to the source. Impacts 

on zooplankton behavior are predicted 

to be negligible, and that would 

translate into negligible impacts on 

feeding mysticetes. Thus, the proposed 

activity is not expected to have any 

habitat-related effects on prey species 

that could cause significant or long-term 

consequences for individual marine 

mammals or their populations. 

Potential Impacts on Availability of 

Affected Species or Stock for Taking for 

Subsistence Uses 

Marine mammals are legally hunted 

in Alaskan waters by coastal Alaska 

Natives and represent between 60% and 

80% of their total subsistence harvest. 

The species regularly harvested by 

subsistence hunters in and around the 

Beaufort Sea are bowhead and beluga 

whales, ringed, spotted, and bearded 

seals, and polar bears. The latter is not 

discussed in this section, as polar bears 

do not fall under the jurisdiction of 

NMFS. The importance of each of the 

subsistence species varies among the 

communities and is mainly based on 

availability and season. 

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The communities closest to the 

project area are, from west to east, the 

villages of Barrow, Nuiqsut, and 

Kaktovik. Barrow is located about 180 

miles west from the survey area. It is the 

largest community on the Alaska’s 

Beaufort Sea coast with a population of 

4,351 in 2004 (DCED 2005). Important 

marine subsistence resources for Barrow 

include bowhead and beluga whales, ice 

seals, polar bears, and walrus. Nuiqsut 

is located near the mouth of the Colville 

River, about 35 miles southwest of the 

project area and had a population of 430 

in 2004 (DCED 2005). The most 

important marine subsistence resource 

for Nuiqsut is the bowhead whale, and 

to a lesser extent beluga whales, polar 

bears and seals. Nuiqsut hunters use 

Cross Island as a base to hunt for 

bowhead whales during the fall 

migration and have historically hunted 

bowhead whales as far east as Flaxman 

Island. Kaktovik is located on Barter 

Island, about 150 miles east of the 

project area and had a population of 284 

in 2004 (DCED 2005). Major marine 

subsistence resources include bowhead 

and beluga whales, seals, and polar 

bears. Approximately 50% of Kaktovik 

households participate in fall whaling 

(Fuller and George 1999). 

(1) Bowhead Whales 

The bowhead whale is a critical 

subsistence and cultural resource for the 

North Slope communities of Barrow, 

Nuiqsut and Kaktovik. Contemporary 

whaling in Kaktovik dates from 1964 

and in Nuiqsut from 1973 (EDAW/ 

AECOM 2007; Galginaitis and Koski 

2002). The number of boats used or 

owned in 2011 by the subsistence 

whaling crew of the villages of 

Kaktovik, Nuiqsut, and Barrow was 8, 

12, and 40, respectively. These numbers 

presumably change from year to year. 

Bowhead harvesting in Barrow occurs 

both during the spring (April–May) and 

fall (September–October) when the 

whales migrate relatively close to shore 

(ADNR 2009). During spring bowheads 

migrate through open ice leads close to 

shore. The hunt takes place from the ice 

using umiaks (bearded seal skin boats). 

During the fall, whaling is shore-based 

and boats may travel up to 30 miles a 

day (EDAW/AECOM 2007). Although in 

Barrow historically most whales were 

taken during spring whaling, the 

efficiency of the spring harvest tends to 

be lower than the autumn harvest due 

to ice and weather conditions as well as 

struck whales escaping under the ice 

(Suydam et al. 2010). In the past few 

years the bowhead fall hunt has become 

increasingly important. Between 1993— 

2010, Barrow landed an average of 22 

bowhead whales per year. 

Nuiqsut and Kaktovik hunters harvest 

bowhead whales only during the fall. 

The bowhead spring migration in the 

Beaufort Sea occurs too far from shore 

for hunting because ice leads do not 

open up nearshore (ADNR 2009). In 

Nuiqsut, whaling takes place from early 

September through mid-to-late 

September as the whales migrate west 

(EDAW/AECOM 2007). Three to five 

whaling crews base themselves at Cross 

Island, a barrier island approximately 35 

miles east of the Simpson Lagoon 

survey area. Nuiqsut whalers harvest an 

average of 3 bowheads each year. 

Whaling from Kaktovik also occurs in 

the fall, primarily from late August 

through late September or early October 

(EDAW/AECOM 2007). Kaktovik 

whalers hunt from the Okpilak and 

Hulahula rivers east to Tapkaurak Point 

(ADNR 2009). Whaling activities are 

staged from the community rather than 

remote camps; most whaling takes place 

within 12 miles of the community 

(ADNR 2009). Kaktovik whalers harvest 

an average of 3 bowhead whales each 

year. 

(2) Beluga Whales 

The harvest of beluga whales is 

managed cooperatively through an 

agreement between NMFS and the 

Alaska Beluga Whale Committee 

(ABWC). From 2002–2006, 5–43 beluga 

whales were harvested annually from 

the Beaufort Sea stock (Allen and 

Angliss 2010), with a mean annual take 

of 25.4 animals. Few beluga whales are 

harvested by either Nuiqsut or Kaktovik. 

(3) Ice Seals 

Seals represent an important 

subsistence resource for the North Slope 

communities. Harvest of bearded seals 

usually takes place during the spring 

and summer open water season from 

Barrow (EDAW/AECOM 2007) with 

only a few animals taken by hunters 

from Kaktovik or Nuiqsut. Seals are also 

taken during the ice-covered season, 

with peak hunting occurring in 

February (ADNR 2009). In 2003, 

Barrow-based hunters harvested 776 

bearded seals, 413 ringed seals and 12 

spotted seals (ADNR 2009). Nuiqsut 

hunters harvest seals in an area from 

Cape Halkett to Foggy Island Bay. For 

the period 2000–2001, Nuiqsut hunters 

harvested one bearded seal and 25 

ringed seals (ADNR 2009). Kaktovik 

hunters also hunt seals year-round. In 

2002–2003, hunters harvested 8 bearded 

seals and 17 ringed seals. 

Potential Impacts to Subsistence Uses 

NMFS has defined ‘‘unmitigable 

adverse impact’’ in 50 CFR 216.103 as: 

* * * an impact resulting from the specified 

activity: (1) That is likely to reduce the 

availability of the species to a level 

insufficient for a harvest to meet subsistence 

needs by: (i) Causing the marine mammals to 

abandon or avoid hunting areas; (ii) Directly 

displacing subsistence users; or (iii) Placing 

physical barriers between the marine 

mammals and the subsistence hunters; and 

(2) That cannot be sufficiently mitigated by 

other measures to increase the availability of 

marine mammals to allow subsistence needs 

to be met. 

Seismic surveys have the potential to 

impact marine mammals hunted by 

Native Alaskans. In the case of 

cetaceans, the most common reaction to 

anthropogenic sounds (as noted 

previously in this document) is 

avoidance of the ensonified area. In the 

case of bowhead whales, this often 

means that the animals could divert 

from their normal migratory path by up 

several kilometers. Additionally, general 

vessel presence in the vicinity of 

traditional hunting areas could 

negatively impact a hunt. 

In the case of subsistence hunts for 

bowhead whales in the Beaufort Sea, 

there could be an adverse impact on the 

hunt if the whales were deflected 

seaward (further from shore) in 

traditional hunting areas. The impact 

would be that whaling crews would 

have to travel greater distances to 

intercept westward migrating whales, 

thereby creating a safety hazard for 

whaling crews and/or limiting chances 

of successfully striking and landing 

bowheads. 

The proposed seismic survey would 

take place between July and September. 

The project area is located 

approximately 35 miles northeast from 

Nuiqsut, 35 miles west from Cross 

Island, 150 miles west from Kaktovik 

and 180 miles east from Barrow. 

Potential impact from the planned 

activities is expected mainly from 

sounds generated by the vessel and 

during active airgun deployment. Due to 

the timing of the project and the 

distance from the surrounding 

communities, it is anticipated to have 

no effects on spring harvesting and little 

or no effects on the occasional summer 

harvest of beluga whale, subsistence 

seal hunts (ringed and spotted seals are 

primarily harvested in winter while 

bearded seals are hunted during July– 

September in the Beaufort Sea), or the 

fall bowhead hunt. The community of 

Nuiqsut may begin fall whaling 

activities in late August to early 

September from Cross Island (east of the 

survey area), and their efforts are 

typically focused on whales 

approaching Cross Island so that any 

harvest would occur before whales 

approached the survey area. As part of 

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the planned mitigation measures (see 

below), BP plans to complete those 

portions of the survey area outside of 

the barrier islands prior to August 25, 

2012. All seismic activities after this 

date would take place inshore of the 

barrier islands, thus avoiding 

subsistence bowhead hunt in the area. 

Finally, BP has signed a Conflict 

Avoidance Agreement (CAA) and will 

prepare a Plan of Cooperation under 50 

CFR 216.104 Article 12 of the MMPA to 

address potential impacts on subsistent 

seal hunting activities. The CAA 

identifies what measures have been or 

will be taken to minimize adverse 

impacts of the planned activities on 

subsistence harvesting (see below for 

more details). BP will meet with the 

AEWC and communities’ Whaling 

Captains’ Associations as part of the 

CAA development, to establish 

avoidance guidelines and other 

mitigation measures to be followed 

where the proposed activities may have 

an impact on subsistence. 

Proposed Mitigation 

In order to issue an incidental take 

authorization under Section 101(a)(5)(D) 

of the MMPA, NMFS must set forth the 

permissible methods of taking pursuant 

to such activity, and other means of 

effecting the least practicable adverse 

impact on such species or stock and its 

habitat, paying particular attention to 

rookeries, mating grounds, and areas of 

similar significance, and on the 

availability of such species or stock for 

taking for certain subsistence uses. 

For the proposed BP open-water 

seismic survey in the Beaufort Sea, BP 

worked with NMFS and proposed the 

following mitigation measures to 

minimize the potential impacts to 

marine mammals in the project vicinity 

as a result of the marine seismic survey 

activities. 

The proposed mitigation measures are 

divided into the following major groups: 

(1) Sound source measurements, (2) 

Establishing exclusion and disturbance 

zones, (3) Vessel and helicopter related 

mitigation measures, and (4) Mitigation 

measures for airgun operations. The 

primary purpose of these mitigation 

measures is to detect marine mammals 

within, or about to enter designated 

exclusion zones and to initiate 

immediate shutdown or power down of 

the airgun(s), therefore it’s very unlikely 

potential injury or TTS to marine 

mammals would occur, and Level B 

behavioral of marine mammals would 

be reduced to the lowest level 

practicable. 

(1) Sound Source Measurements 

The acoustic monitoring program has 

two objectives: (1) To verify the 

modeled distances to the exclusion and 

disturbance zones from the 640 in3 and 

320 in3 airgun arrays and to provide 

corrected distances to the PSOs; and (2) 

to measure vessel sounds (i.e., received 

levels referenced to 1 m from the sound 

source) of each representative vessel of 

the seismic fleet, to obtain information 

on the sounds produced by these 

vessels. 

Verification and Establishment of 

Exclusion and Disturbance Zones 

Acoustic measurements to calculate 

received sound levels as a function of 

distance from the airgun sound source 

will be conducted within 72 hours of 

initiation of the seismic survey. These 

measurements will be conducted 

according to a standard protocol for the 

640 in3 array, the 320 in3 array and the 

40 in3 gun, both inside and outside the 

barrier islands. The results of these 

acoustic measurements will be used to 

re-define, if needed, the distances to 

received levels of 190, 180, 160 and 120 

dB. The distances of the received levels 

as a function of the different sound 

sources (varying discharge volumes) 

will be used to guide power-down and 

ramp-up procedures. A preliminary 

report describing the methodology and 

results of the verification for at least the 

190 dB and 180 dB (rms) exclusion 

zones will be submitted to NMFS within 

14 days of completion of the 

measurements. 

Measurements of Vessel Sounds 

BP intends to measure vessel sounds 

of each representative vessel. The exact 

scope of the source level measurements 

(back-calculated as received levels at 1 

m from the source) will follow a predefined protocol to eliminate the 

complex interplay of factors that 

underlie such measurements, such as 

bathymetry, vessel activity, location, 

season, etc. Where possible and 

practical the monitoring protocol will be 

developed in alignment with other 

existing vessel source level 

measurements. 

(2) Establishing Exclusion and 

Disturbance Zones 

Under current NMFS guidelines, the 

‘‘exclusion zone’’ for marine mammal 

exposure to impulse sources is 

customarily defined as the area within 

which received sound levels are ≥180 

dB re 1 mPa (rms) for cetaceans and ≥190 

dB re 1 mPa (rms) for pinnipeds. These 

safety criteria are based on an 

assumption that SPL received at levels 

lower than these will not injure these 

animals or impair their hearing abilities, 

but that at higher levels might have 

some such effects. Disturbance or 

behavioral effects to marine mammals 

from underwater sound may occur after 

exposure to sound at distances greater 

than the exclusion zones (Richarcdson 

et al. 1995). 

An acoustic propagation model, i.e., 

JASCO’s Marine Operations Noise 

Model (MONM), was used to estimate 

the distances to received sound levels of 

190, 180, 170, 160, and 120 dB re 1mPa 

(rms) for pulsed sounds from the 640 in3

and 320 in3 airgun arrays. Modeling 

methodology and results are described 

in detail in the appendix of the BP’s 

IHA application (Warner and Hipsey 

2011). Table 2 summarizes the distances 

from the source to specific received 

sound levels based on MONM 

modeling. 

TABLE 2—ESTIMATED DISTANCES TO SPECIFIED RECEIVED SPL (RMS) FROM AIRGUN ARRAYS WITH A TOTAL DISCHARGE

VOLUME OF 640 IN3, 320 IN3, AND 40 IN3

Received levels (dB re 1 μPa rms) 

Distance in meters 

(inside barrier islands) 

Distance in meters 

(outside barrier islands) 

640 in3 320 in3 40 in3 640 in3 40 in3

190 ....................................................................................... 310 160 16 120 <50 

180 ....................................................................................... 750 480 59 950 <50 

170 ....................................................................................... 1,200 930 300 2,500 120 

160 ....................................................................................... 1,800 1,500 700 5,500 810 

120 ....................................................................................... 6,400 5,700 3,700 44,000 16,000 

Note: Values are based on 2 m tow depth for the 640 in3 and 40 in3 array, and a 1 m tow depth for the 320 in3 array. 

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The distances to received sound 

levels of 160 dB re 1 mPa (rms) of the 

640 in3 airgun array were used to 

calculate the numbers of marine 

mammals potentially harassed by the 

activities. The distances to received 

levels of 180 dB and 190 dB re 1 mPa 

(rms) are mainly relevant as exclusion 

radii to avoid level A harassment of 

marine mammals through 

implementation of shut down and 

power down measures (see details 

below). 

(3) Vessel and Helicopter Related 

Mitigation Measures 

This proposed mitigation measures 

apply to all vessels that are part of the 

Simpson Lagoon seismic survey, 

including crew transfer vessels. 

• Vessel operators shall avoid 

concentrations or groups of whales 

and vessels shall not be operated in 

a way that separates members of a 

group. In proximity of feeding 

whales or aggregations, vessel speed 

shall be less than 10 knots. 

• When within 900 feet (300 m) of 

whales vessel operators shall take 

every effort and precaution to avoid 

harassment of these animals by: 

Æ Reducing speed and steering 

around (groups of) whales if 

circumstances allow, but never 

cutting off a whale’s travel path; 

Æ Avoiding multiple changes in 

direction and speed. 

• Vessel operators shall check the 

waters immediately adjacent to a 

vessel to ensure that no marine 

mammals will be injured when the 

vessel’s propellers (or screws) are 

engaged. 

• To minimize collision risk with 

marine mammals, vessels shall not 

be operated at speeds that would 

make collisions with whales likely. 

When weather conditions require, 

such as when visibility drops, 

vessels shall adjust speed 

accordingly to avoid the likelihood 

of injury to whales. 

• Sightings of dead marine mammals 

would be reported immediately to 

the BP representative. BP is 

responsible for ensuring reporting 

of the sightings according to the 

guidelines provided by NMFS. 

• In the event that any aircraft (such as 

helicopters) are used to support the 

planned survey, the mitigation 

measures below would apply: 

Æ Under no circumstances, other than 

an emergency, shall aircraft be 

operated at an altitude lower than 

1,000 feet above sea level (ASL) 

when within 0.3 mile (0.5 km) of 

groups of whales. 

Æ Helicopters shall not hover or circle 

above or within 0.3 mile (0.5 km) of 

groups of whales. 

(4) Mitigation Measures for Airgun 

Operations 

The primary role for airgun mitigation 

during seismic survey is to monitor 

marine mammals near the seismic 

source vessel during all daylight airgun 

operations and during any nighttime 

start-up of the airguns. During the 

seismic survey PSOs will monitor the 

pre- established exclusion zones for the 

presence of marine mammals. When 

marine mammals are observed within, 

or about to enter, designated safety 

zones, PSOs have the authority to call 

for immediate power down (or 

shutdown) of airgun operations as 

required by the situation. A summary of 

the procedures associated with each 

mitigation measure is provided below. 

Ramp Up Procedure 

Ramp up procedures for an airgun 

array involve a step-wise increase in the 

number of operating airguns until the 

required discharge volume is achieved. 

The purpose of a ramp up (sometimes 

also referred to as soft start) is to 

provide marine mammals in the vicinity 

of the activity the opportunity to leave 

the area and thus avoid any potential 

injury or impairment of their hearing 

abilities. 

The rate of ramp up shall be no more 

than 6 dB of source level per 5 min 

period. A common procedure is to 

double the number of operating airguns 

at 5-min intervals, starting with the 

smallest gun in the array. BP states that 

it intends to double the number of 

airguns operating at 5 minute intervals 

during ramp up. For the 640 cu in 

airgun array of the Simpson Lagoon 

seismic survey this is estimated to take 

20 minutes, and for the 320 in3 array 15 

minutes. During ramp up, the safety 

zone for the full airgun array will be 

observed. The ramp up procedures will 

be applied as follows: 

• A ramp up, following a cold start, 

can be applied if the exclusion zone has 

been free of marine mammals for a 

consecutive 30-minute period. The 

entire exclusion zone must have been 

visible during these 30 minutes. If the 

entire exclusion zone is not visible, then 

ramp up from a cold start cannot begin. 

• Ramp up procedures from a cold 

start will be delayed if a marine 

mammal is sighted within the exclusion 

zone during the 30-minute period prior 

to the ramp up. The delay will last until 

the marine mammal(s) has been 

observed to leave the exclusion zone or 

until the animal(s) is not sighted for at 

least 15 or 30 minutes. The 15 minutes 

applies to small toothed whales and 

pinnipeds, while a 30 minute 

observation period applies to baleen 

whales and large toothed whales. 

• A ramp up, following a shutdown, 

can be applied if the marine mammal(s) 

for which the shutdown occurred has 

been observed to leave the exclusion 

zone or until the animal(s) is not sighted 

for at least 15 minutes (small toothed 

whales and pinnipeds) or 30 minutes 

(baleen whales and large toothed 

whales). This assumes there was a 

continuous observation effort prior to 

the shutdown and the entire exclusion 

zone is visible. 

• If, for any reason, electrical power 

to the airgun array has been 

discontinued for a period of 10 minutes 

or more, ramp-up procedures need to be 

implemented. Only if the PSO watch 

has been suspended, a 30-minute 

clearance of the exclusion zone is 

required prior to commencing ramp-up. 

Discontinuation of airgun activity for 

less than 10 minutes does not require a 

ramp-up. 

• The seismic operator and PSOs will 

maintain records of the times when 

ramp-ups start and when the airgun 

arrays reach full power. 

Power-Down Procedures 

A power down is the immediate 

reduction in the number of operating 

airguns such that the radii of the 190 dB 

and 180 dB (rms) zones are decreased to 

the extent that an observed marine 

mammal is not in the applicable safety 

zone of the full array. During a power 

down, one airgun (or some other 

number of airguns less than the full 

airgun array) continues firing. The 

continued operation of one airgun is 

intended to (a) alert marine mammals to 

the presence of airgun activity, and (b) 

retain the option of initiating a ramp up 

to full operations under poor visibility 

conditions. 

• The airgun array shall be 

immediately powered down whenever a 

marine mammal is sighted approaching 

close to or within the applicable 

exclusion zone of the full array, but is 

outside the applicable exclusion zone of 

the single mitigation airgun. 

• If a marine mammal is already 

within the exclusion zone when first 

detected, the airguns will be powered 

down immediately. 

• Following a power-down, ramp up 

to the full airgun array will not resume 

until the marine mammal has cleared 

the exclusion zone. The animal will be 

considered to have cleared the 

exclusion zone if it is visually observed 

to have left the exclusion zone of the 

full array, or has not been seen within 

the zone for 15 minutes (pinnipeds or 

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small toothed whales) or 30 minutes 

(baleen whales or large toothed whales). 

Shutdown Procedures 

• The operating airgun(s) will be 

shutdown completely if a marine 

mammal approaches or enters the 190 or 

180 dB (rms) exclusion zone of the 

smallest airgun. 

• Airgun activity will not resume 

until the marine mammal has cleared 

the exclusion zone of the full array. The 

animal will be considered to have 

cleared the exclusion zone as described 

above under ramp up procedures. 

Poor Visibility Conditions 

BP plans to conduct 24-hour 

operations. PSOs will not be on duty 

during ongoing seismic operations 

during darkness, given the very limited 

effectiveness of visual observation at 

night (there will be no periods of 

darkness in the survey area until midAugust). The proposed provisions 

associated with operations at night or in 

periods of poor visibility include the 

following: 

• If during foggy conditions, heavy 

snow or rain, or darkness (which may be 

encountered starting in late August), the 

full 180 dB exclusion zone is not 

visible, the airguns cannot commence a 

ramp-up procedure from a full shutdown. 

• If one or more airguns have been 

operational before nightfall or before the 

onset of poor visibility conditions, they 

can remain operational throughout the 

night or poor visibility conditions. In 

this case ramp-up procedures can be 

initiated, even though the exclusion 

zone may not be visible, on the 

assumption that marine mammals will 

be alerted by the sounds from the single 

airgun and have moved away. 

In addition, NMFS proposes the 

following additional protective 

mitigation and monitoring during the 

periods of darkness or low visibility. 

Specifically, NMFS does not 

recommend keeping one airgun (the so 

called ‘‘mitigation gun’’ in past IHAs) 

firing for long periods of time with no 

seismic operation ongoing during 

darkness or other periods of poor 

visibility on the previous assumption 

that marine mammals will be alerted by 

the sounds from the single airgun so 

that a cold start with pre-survey 

monitoring could be avoided, since 

there is no scientific evidence that such 

technique works (Tyack 2009). On the 

contrary, keeping an airgun firing 

unnecessarily for long periods of time 

would only introduce more noise into 

the water. Therefore, for seismic surveys 

that would start during night time and 

low visibility, NMFS proposes to 

require that PSOs use vessel lights, 

night vision devices (NVDs), and/or 

forward looking infrared (FLIR) to 

observe as much as possible for 30 

minutes before ramping up the airgun 

array. PSOs will be called up to observe 

at nighttime during the 30-min periods 

prior to ramp-ups as well as during 

ramp-ups. 

Mitigation Measures for Subsistence 

Activities 

(1) Subsistence Mitigation Measures 

To limit potential impacts to the 

bowhead whale migration and the 

subsistence hunt, BP would not conduct 

airgun operations in the area north of 

the barrier islands after 25 August. 

(2) Plan of Cooperation (POC) and 

Conflict Avoidance Agreement (CAA) 

Regulations at 50 CFR 216.104(a)(12) 

require IHA applicants for activities that 

take place in Arctic waters to provide a 

POC or information that identifies what 

measures have been taken and/or will 

be taken to minimize adverse effects on 

the availability of marine mammals for 

subsistence purposes. 

BP has signed a Conflict Avoidance 

Agreement (CAA) with the Alaska 

Eskimo Whaling Commission (AEWC) 

and communities’ Whaling Captains’ 

Association for the proposed 2012 

Simpson Lagoon OBV seismic survey. 

The main purpose of the CAA is to 

provide (1) equipment and procedures 

for communications between 

subsistence participants and industry 

participants; (2) avoidance guidelines 

and other mitigation measures to be 

followed by the industry participants 

working in or transiting the vicinity of 

active subsistence hunters, in areas 

where subsistence hunters anticipate 

hunting, or in areas that are in sufficient 

proximity to areas expected to be used 

for subsistence hunting that the planned 

activities could potentially adversely 

affect the subsistence bowhead whale 

hunt through effects on bowhead 

whales; and (3) measures to be taken in 

the event of an emergency occurring 

during the term of the CAA. 

In the CAA, BP agrees to employ a 

Marine Mammal Observer/Inupiat 

Communitor (MMO/IC) on board each 

primary sound source vessel owned or 

operated by BP in the Beaufort Sea, and 

that native residents of the eleven 

villages represented by the AEWC shall 

be given preference in hiring for MMO/ 

IC positions. 

The CAA states that all vessels 

(operated by BP) shall report to the 

appropriate Communication Center 

(Com-Center) at least once every six 

hours commencing with a call at 

approximately 06:00 hours. The 

appropriate Com-Center shall be 

notified if there is any significant 

change in plans, such as an 

unannounced start-up of operations or 

significant deviations from announced 

course, and such Com-Center shall 

notify all whalers of such changes. 

The CAA further states that each 

Com-Center shall have an Inupiat 

operator (‘‘Com- Center operator’’) on 

duty 24 hours per day from August 15, 

or one week before the start of the fall 

bowhead whale hunt in each respective 

village, until the end of the bowhead 

whale subsistence hunt. 

The CAA also states that following the 

end of the fall 2012 bowhead whale 

subsistence hunt and prior to the 2013 

pre-season introduction meetings, the 

industry participant that establishes the 

Deadhorse and Kaktovik Com Center 

will offer to the AEWC Chairman to host 

a joint meeting with all whaling 

captains of the villages of Nuiqsut, 

Kaktovik, and Barrow, the Marien 

Mammal Observer/Inupiat 

Communicators stationed on the 

industry participants’ vessels in the 

Beaufort Sea, and with the Chairman 

and Exective Director of the AEWC, at 

a mutually agreed upon time and place 

on North Slope of Alaska, to review the 

results of the 2012 Beaufort Sea open 

water season. 

In addition, BP is developing a ‘‘Plan 

of Cooperation’’ (POC) for the proposed 

2012 seismic survey in the Simpson 

Lagoon of the Alaskan Beaufort Sea in 

consultation with representatives of 

communities along the Beaufort Sea 

coast at Barrow, Nuiqsut, and Kaktovik, 

on issues related to subsistence seal 

hunt. Mitigation measures similar to 

those listed in the CAA will be 

identified in the POC, and a final draft 

of the POC will be delivered to NMFS 

and other regulatory agencies. 

Mitigation Conclusions 

NMFS has carefully evaluated the 

applicant’s proposed mitigation 

measures and considered a range of 

other measures in the context of 

ensuring that NMFS prescribes the 

means of effecting the least practicable 

impact on the affected marine mammal 

species and stocks and their habitat. Our 

evaluation of potential measures 

included consideration of the following 

factors in relation to one another: 

• The manner in which, and the 

degree to which, the successful 

implementation of the measure is 

expected to minimize adverse impacts 

to marine mammals; and 

• The practicability of the measure 

for applicant implementation. 

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Based on our evaluation of the 

applicant’s proposed measures, as well 

as other measures considered by NMFS, 

NMFS has preliminarily determined 

that the proposed mitigation measures 

provide the means of effecting the least 

practicable impact on marine mammal 

species or stocks and their habitat, 

paying particular attention to rookeries, 

mating grounds, and areas of similar 

significance. 

Proposed Monitoring and Reporting 

In order to issue an ITA for an 

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

MMPA states that NMFS must set forth 

‘‘requirements pertaining to the 

monitoring and reporting of such 

taking’’. The MMPA implementing 

regulations at 50 CFR 216.104(a)(13) 

indicate that requests for ITAs must 

include the suggested means of 

accomplishing the necessary monitoring 

and reporting that will result in 

increased knowledge of the species and 

of the level of taking or impacts on 

populations of marine mammals that are 

expected to be present in the proposed 

action area. 

(1) Proposed Monitoring Measures 

The monitoring plan proposed by BP 

can be found in its IHA application. The 

plan may be modified or supplemented 

based on comments or new information 

received from the public during the 

public comment period. A summary of 

the primary components of the plan 

follows. 

There will be two vessel-based 

monitoring programs during the 

Simpson Lagoon OBC seismic survey. 

One program involves the presence of 

protected species observers (PSOs) on 

the seismic source vessels during the 

entire seismic survey period. The other 

vessel-based program involves two 

PSOs on a monitoring vessel outside the 

barrier islands after 25 August. 

Visual Monitoring From Source Vessels 

Two PSOs will be present on each 

seismic source vessel. Of these two 

PSOs, one will be on watch at all times 

during daylight hours to monitor the 

190 and 180 dB exclusion zones for the 

presence of marine mammals during 

airgun operations. During the fall 

bowhead whale migration season the 

160 dB disturbance zone will also be 

monitored for the presence of groups of 

12 or more baleen whales. The 120 dB 

disturbance zone for bowhead cow/calf 

pairs will be monitored from another 

vessel (see section ‘‘Visual Monitoring 

Outside the Barrier Islands’’). The main 

objectives of the vessel-based marine 

mammal monitoring program from the 

source vessels are as follows: 

• To implement mitigation measures 

during seismic operations (e.g. course 

alteration, airgun power-down, shutdown and ramp-up); 

• To record all marine mammal data 

needed to estimate the number of 

marine mammals potentially affected, 

which must be reported to NMFS within 

90 days after the survey; 

• To compare the distance and 

distribution of marine mammals relative 

to the source vessel at times with and 

without seismic activity; and 

• To obtain data on the behavior and 

movement patterns of marine mammals 

observed and compare those at times 

with and without seismic activity. 

Marine Mammal Observer Protocol 

BP intends to work with experienced 

PSOs that have had previous experience 

working on seismic survey vessels, 

which will be especially important for 

the lead PSO on the source vessels. At 

least one Alaska Native resident, who is 

knowledgeable about Arctic marine 

mammals and the subsistence hunt, is 

expected to be included as one of the 

team members aboard the vessels. 

Before the start of the seismic survey the 

crew of the seismic source vessels will 

be briefed on the function of the PSOs, 

their monitoring protocol, and 

mitigation measures to be implemented. 

They will also be aware of the 

monitoring objectives of the dedicated 

monitoring vessel, and how their 

observations can affect the operations. 

On all source vessels, at least one 

observer will monitor for marine 

mammals at any time during daylight 

hours (there will be no periods of total 

darkness until mid-August). PSOs will 

be on duty in shifts of a maximum of 4 

hours at a time, although the exact shift 

schedule will be established by the lead 

PSO in consultation with the other 

PSOs. 

The three source vessels will offer 

suitable platforms for PSOs. 

Observations will be made from 

locations where PSOs have the best 

view around the vessel. During daytime, 

the PSO(s) will scan the area around the 

vessel systematically with reticle 

binoculars (e.g., 7 × 50 Fujinon) and 

with the naked eye. Laser range-finding 

binoculars (Leica LRF 1200 laser 

rangefinder or equivalent) will be 

available to assist with distance 

estimation, using other vessels in the 

area as targets. Laser range finding 

binoculars are generally not useful in 

measuring distances to animals directly. 

Communication Procedures 

When marine mammals in the water 

are detected within or about to enter the 

designated safety zones, the airgun(s) 

power-down or shut-down procedures 

will be implemented immediately. To 

assure prompt implementation of 

power-downs and shut- downs, 

multiple channels of communication 

between the PSOs and the airgun 

technicians will be established. During 

the power-down and shut-down, the 

PSO(s) will continue to maintain watch 

to determine when the animal(s) are 

outside the safety radius. Airgun 

operations can be resumed with a rampup procedure (depending on the extent 

of the power down) if the observers 

have visually confirmed that the 

animal(s) moved outside the exclusion 

zone, or if the animal(s) were not 

observed within the safety zone for 15 

minutes (pinnipeds and small toothed 

whales) or for 30 minutes (for baleen 

whales and large toothed whales). Direct 

communication with the airgun operator 

will be maintained throughout these 

procedures. 

Data Recording 

All marine mammal observations and 

any airgun power-down, shut-down and 

ramp- up will be recorded in a 

standardized format. Data will be 

entered into a custom database using a 

notebook computer. The accuracy of the 

data entry will be verified by 

computerized validity data checks as 

the data are entered and by subsequent 

manual checking of the database after 

each day. These procedures will allow 

initial summaries of data to be prepared 

during and shortly after the field 

program, and will facilitate transfer of 

the data to statistical, graphical, or other 

programs for further processing and 

archiving. 

Visual Monitoring Outside the Barrier 

Islands 

The main purpose of the PSOs on the 

monitoring vessel that will operate 

outside the barrier islands is to monitor 

the 120 dB disturbance zone during 

daylight hours for the presence of four 

or more bowhead cow/calf pairs. The 

predicted distances to received levels of 

120 dB are 6.4 km for the 640 in3 array 

and 5.7 km for the 320 in3 array. The 

distance to the 160 dB disturbance zone 

is small enough (1.8 km for the 640 in3

and 1.5 km for the 320 in3 array) to be 

covered by the PSOs on the source 

vessels. Of the two PSOs on the 

monitoring vessel, one will be on watch 

at all times during daylight hours to 

monitor the disturbance zones and to 

communicate any sightings of four 

bowhead cow/calf pairs to the PSOs on 

the source vessels. The shift schedule 

and observer protocol will be similar to 

that of the PSOs on the source vessels. 

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Channels of communication between 

the lead PSOs on the source vessels and 

the dedicated monitoring vessel will 

also be established. If four or more 

bowhead cow/calf pairs are observed 

within or entering the 120 dB 

disturbance zone the lead PSO on 

monitoring vessel will immediately 

contact the lead PSO on the source 

vessel, who will ensure prompt 

implementation of airgun power downs 

or shutdowns. The lead PSO of the 

monitoring vessel will continue 

monitoring the 120 dB zone and notify 

the PSO on the source vessel when the 

cow/calf pairs have left the safety zone 

or when they haven’t been observed 

within the safety zone for 30 minutes. 

Under these conditions ramp-up can be 

initiated. 

These vessel based surveys outside 

the barrier islands will be conducted up 

to 3 days per week, weather depending. 

Anticipated start date is August 25, 

2012, and these surveys will be 

continuing until the end of the data 

acquisition period. During this period 

data acquisition will take place only 

inside the barrier islands. The vessel 

will follow transect lines within the 120 

dB zone that are designed in such a way 

that the area ensonified by 120 dB or 

more will be covered. The exact start 

and end point will depend on the area 

to be covered by the source vessels 

during that particular day. 

Monitoring Plan Peer Review 

The MMPA requires that monitoring 

plans be independently peer reviewed 

‘‘where the proposed activity may affect 

the availability of a species or stock for 

taking for subsistence uses’’ (16 U.S.C. 

1371(a)(5)(D)(ii)(III)). Regarding this 

requirement, NMFS’ implementing 

regulations state, ‘‘Upon receipt of a 

complete monitoring plan, and at its 

discretion, [NMFS] will either submit 

the plan to members of a peer review 

panel for review or within 60 days of 

receipt of the proposed monitoring plan, 

schedule a workshop to review the 

plan’’ (50 CFR 216.108(d)). 

NMFS convened an independent peer 

review panel to review BP’s mitigation 

and monitoring plan in its IHA 

application for taking marine mammals 

incidental to the proposed OBC seismic 

survey in the Simpson Lagoon of the 

Alaskan Beaufort Sea, during 2012. The 

panel met on January 5 and 6, 2012, and 

provided their final report to NMFS on 

February 29, 2012. The full panel report 

can be viewed at: http:// 

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

incidental.htm#applications. 

NMFS provided the panel with BP’s 

monitoring and mitigation plan and 

asked the panel to address the following 

questions and issues for BP’s plan: 

• Will the applicant’s stated 

objectives effectively further the 

understanding of the impacts of their 

activities on marine mammals and 

otherwise accomplish the goals stated 

above? If not, how should the objectives 

be modified to better accomplish the 

goals above? 

• Can the applicant achieve the stated 

objectives based on the methods 

described in the plan? 

• Are there technical modifications to 

the proposed monitoring techniques and 

methodologies proposed by the 

applicant that should be considered to 

better accomplish their stated 

objectives? 

• Are there techniques not proposed 

by the applicant (i.e., additional 

monitoring techniques or 

methodologies) that should be 

considered for inclusion in the 

applicant’s monitoring program to better 

accomplish their stated objectives? And 

• What is the best way for an 

applicant to present their data and 

results (formatting, metrics, graphics, 

etc.) in the required reports that are to 

be submitted to NMFS (i.e., 90-day 

report and comprehensive report)? 

The peer review panel report contains 

recommendations that the panel 

members felt were applicable to the BP’s 

monitoring plans. Specifically the panel 

commented on issues related to: (1) 

Vessel-based marine mammal observers 

(MMOs), (2) MMO training, (3) Data 

recording, (4) Data analysis, and (5) 

Acoustical monitoring. 

NMFS has reviewed the report and 

evaluated all recommendations made by 

the panel. NMFS has determined that 

there are several measures that BP can 

incorporate into its 2012 OBC seismic 

survey. Additionally, there are other 

recommendations that NMFS has 

determined would also result in better 

data collection, and could potentially be 

implemented by oil and gas industry 

applicants, but which likely could not 

be implemented for the 2012 open water 

season due to technical issues (see 

below). While it may not be possible to 

implement those changes this year, 

NMFS believes that they are worthwhile 

and appropriate suggestions that may 

require a bit more time to implement, 

and BP should consider incorporating 

them into future monitoring plans 

should BP decide to apply for IHAs in 

the future. 

The following subsections lay out 

measures that NMFS recommends for 

implementation as part of the 2012 OBC 

seismic survey by BP and those that are 

recommended for future programs. 

Recommendations for Inclusion in the 

2012 Monitoring Plan 

The peer review panel’s report 

contains several recommendations 

regarding vessel- based marine mammal 

observers, marine mammal monitor 

(MMO) training, data recording, data 

analysis and presentation of data in 

reports, and acoustic monitoring, which 

NMFS agrees that BP should 

incorporate: 

(1) Vessel-Based Marine Mammal 

Observers 

• Utilize crew members to assist the 

MMOs. Crew members should not be 

used as primary MMOs because they 

have other duties and generally do not 

have the same level of expertise, 

experience, or training as MMOs, but 

they could be stationed on the fantail of 

the vessel to observe the near field, 

especially the area around the airgun 

array and implement a rampdown or 

shutdown if a marine mammal enters 

the safety zone (or exclusion zone). 

• If crew members are to be used as 

MMOs, they should go through some 

basic training consistent with the 

functions they will be asked to perform. 

The best approach would be for crew 

members and MMOs to go through the 

same training together. 

• As BP plans to have a marine 

mammal survey vessel outside the 

barrier islands after 25 August, the 

panel recommends BP use MMOs on the 

vessel to monitor for the presence and 

behavior of marine mammals in the 

offshore area projected to be exposed to 

seismic sounds. 

(2) MMO Training 

• BP could improve its MMO training 

by implementing panel 

recommendations from previous years 

(on other seismic survey programs). 

These recommendations include: 

Æ Observers should be trained using 

visual aids (e.g., videos, photos), to help 

them identify the species that they are 

likely to encounter in the conditions 

under which the animals will likely be 

seen. 

Æ Observer teams should include 

Alaska Natives, and all observers should 

be trained together. Whenever possible, 

new observers should be paired with 

experienced observers to avoid 

situations where lack of experience 

impairs the quality of observations. 

Æ Observers should understand the 

importance of classifying marine 

mammals as ‘‘unknown’’ or 

‘‘unidentified’’ if they cannot identify 

the animals to species with confidence. 

In those cases, they should note any 

information that might aid in the 

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identification of the marine mammal 

sighted. For example, for an 

unidentified mysticete whale, the 

observers should record whether the 

animal had a dorsal fin. 

Æ Observers should use the best 

possible positions for observing (e.g., 

outside and as high on the vessel as 

possible), taking into account weather 

and other working conditions. 

• BP should train its MMOs to follow 

a scanning schedule that consistently 

distributes scanning effort according to 

the purpose and need for observations. 

For example, the schedule might call for 

60 percent of scanning effort to be 

directed toward the near field and 40 

percent at the far field. All MMOs 

should follow the same schedule to 

ensure consistency in their scanning 

efforts. 

• MMOs also need training in 

documenting the behaviors of marine 

mammals. MMOs should simply record 

the primary behavioral state (i.e., 

traveling, socializing, feeding, resting, 

approaching or moving away from 

vessels) and relative location of the 

observed marine mammals. 

(3) Data Recording 

• MMOs should record observations 

of marine mammals hauled out on 

barrier islands. Because of the location 

of BP’s proposed survey, most (if not all) 

of the marine mammals observed in the 

lagoon will be pinnipeds. It is feasible 

that the surveys may alter the hauling 

out patterns of pinnipeds, so 

observations of them should be 

recorded. 

• BP should work with its observers 

to develop a means for recording data 

that does not reduce observation time 

significantly. Possible options include 

the use of a voice recorder during 

observations followed by later 

transcriptions, or well-designed 

software programs that minimize the 

time required to enter data. Other 

techniques also may be suitable. 

(4) Data Analysis and Presentation of 

Data in Reports 

• Estimation of potential takes or 

exposures should be improved for times 

with low visibility (such as during fog 

or darkness) through interpolation or 

possibly using a probability approach. 

For instance, for periods of fog or 

darkness one could use marine mammal 

observations obtained during a specified 

period of time before or fter the time 

when visibility was restricted. Those 

data could be used to interpolate 

possible takes during periods of 

restricted visibility. 

• Simpson Lagoon is relatively 

shallow, and marine mammal 

distribution likely will be closely linked 

to water depth. To account for this 

confounding factor, depth should be 

continuously recorded by the vessel and 

for each marine mammal sighting. Water 

depth should be accounted for in the 

analysis of take estimates. 

• BP should be very clear in their 

report about what periods are 

considered ‘‘non-seismic’’ for analyses. 

• BP should examine data from 

BWASP and other such programs to 

assess possible impacts from their 

seismic survey. 

• The panel states that it believes the 

best ways to present data and results are 

described in peer-review reports from 

previous years. These recommendations 

include: 

Æ To better assess impacts to marine 

mammals, data analysis should be 

separated into periods when a seismic 

airgun array (or a single mitigation 

airgun) is operating and when it is not. 

Final and comprehensive reports to 

NMFS should summarize and plot: 

D Data for periods when a seismic 

array is active and when it is not; and 

D The respective predicted received 

sound conditions over fairly large areas 

(tens of km) around operations. 

Æ To help evaluate the effectiveness 

of MMOs and more effectively estimate 

take, reports should include sightability 

curves (detection functions) for 

distance-based analyses. 

Æ To better understand the potential 

effects of oil and gas activities on 

marine mammals and to facilitate 

integration among companies and other 

researchers, the following data should 

be obtained and provided electronically 

in the 90-day report: 

D The location and time of each aerial 

or vessel-based sighting or acoustic 

detection; 

D Position of the sighting or acoustic 

detection relative to ongoing operations 

(i.e., distance from sightings to seismic 

operation, drilling ship, support ship, 

etc.), if known; 

D The nature of activities at the time 

(e.g., seismic on/off); 

D Any identifiable marine mammal 

behavioral response (sighting data 

should be collected in a manner that 

will not detract from the MMO’s ability 

to detect marine mammals); and 

D Adjustments made to operating 

procedures. 

Æ BP should improve take estimates 

and statistical inference into effects of 

the activities by incorporating the 

following measures: 

D Reported results from all hypothesis 

tests should include estimates of the 

associated statistical power. 

D Estimate and report uncertainty in 

all take estimates. Uncertainty could be 

expressed by the presentation of 

confidence limits, a minimummaximum, posterior probability 

distribution, etc.; the exact approach 

would be selected based on the 

sampling method and data available. 

(5) Acoustical Monitoring 

• BP should also use the offshore 

vessel to monitor (periodically) the 

propagation of airgun sounds from 

within the lagoon into offshore areas 

during its marine mammal survey using 

a dipping hydrophone. 

• To help verify the propagation 

model results, the panel also 

recommends additional acoustic 

monitoring with bottom mounted 

recorders. Recorders should be 

deployed throughout the seismic 

survey. One suggestion is to deploy 

instruments including: one at the cut, or 

break, between Leavitt and Spy islands 

at about the 5 m isobath; one north of 

the center of Leavitt Island at the 10 m 

isobath; and one off the east end of 

Pingok Island at the 10 m isobath. 

Recommendations To Be Considered for 

Future Monitoring Plans 

In addition, the panelists 

recommended that (1) BP continue to 

develop and test observational aids to 

assist with visibility during night, poor 

light conditions, inclement weather, 

etc.; and (2) BP conduct additional 

acoustic monitoring with bottom 

mounted recorders to monitor for 

calling marine mammals. It may be 

possible to evaluate calling rates relative 

to seismic operations or received levels 

of seismic sounds. Additionally, Shell 

will have several acoustic arrays in the 

general area. Those arrays will provide 

a basis for determining locations of 

calling marine mammals. NMFS should 

encourage BP to request data from Shell 

to help examine impacts of the seismic 

survey on the distribution of calling 

bowheads and other marine mammals. 

After discussion with BP, NMFS 

decided not to implement these two 

recommendations for BP’s 2012 OBC 

seismic survey because most of BP’s 

survey would occur during the time 

when there will be very short low-light 

hours. As for the second 

recommendation, NMFS realized that 

given the complexity in marine mammal 

passive acoustic localization, BP will 

not have the time to implement this 

recommendation for its 2012 survey. 

(2) Reporting Measures 

Sound Source Verification Reports 

A report on the preliminary results of 

the sound source verification 

measurements, including the measured 

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190, 180, 160, and 120 dB (rms) radii of 

the airgun sources, would be submitted 

within 14 days after collection of those 

measurements at the start of the field 

season. This report will specify the 

distances of the exclusion zones that 

were adopted for the survey. 

Technical Reports 

The results of BP’s 2012 vessel-based 

monitoring, including estimates of 

‘‘take’’ by harassment, would be 

presented in the ‘‘90-day’’ and Final 

Technical reports, if the IHA is issued 

and the proposed OBC seismic survey is 

conducted. The Technical Reports 

should be submitted to NMFS within 90 

days after the end of the seismic survey. 

The Technical Reports will include: 

(a) Summaries of monitoring effort 

(e.g., total hours, total distances, and 

marine mammal distribution through 

the study period, accounting for sea 

state and other factors affecting 

visibility and detectability of marine 

mammals); 

(b) Analyses of the effects of various 

factors influencing detectability of 

marine mammals (e.g., sea state, number 

of observers, and fog/glare); 

(c) Species composition, occurrence, 

and distribution of marine mammal 

sightings, including date, water depth, 

numbers, age/size/gender categories (if 

determinable), group sizes, and ice 

cover; 

(d) To better assess impacts to marine 

mammals, data analysis should be 

separated into periods when a seismic 

airgun array (or a single mitigation 

airgun) is operating and when it is not. 

Final and comprehensive reports to 

NMFS should summarize and plot: 

• Data for periods when a seismic 

array is active and when it is not; and 

• The respective predicted received 

sound conditions over fairly large areas 

(tens of km) around operations; 

(e) Sighting rates of marine mammals 

during periods with and without airgun 

activities (and other variables that could 

affect detectability), such as: 

• Initial sighting distances versus 

airgun activity state; 

• Closest point of approach versus 

airgun activity state; 

• Observed behaviors and types of 

movements versus airgun activity state; 

• Numbers of sightings/individuals 

seen versus airgun activity state; 

• Distribution around the survey 

vessel versus airgun activity state; and 

• Estimates of take by harassment; 

(f) Reported results from all 

hypothesis tests should include 

estimates of the associated statistical 

power when practicable; 

(g) Estimate and report uncertainty in 

all take estimates. Uncertainty could be 

expressed by the presentation of 

confidence limits, a minimummaximum, posterior probability 

distribution, etc.; the exact approach 

would be selected based on the 

sampling method and data available; 

(h) The report should clearly compare 

authorized takes to the level of actual 

estimated takes; and 

Notification of Injured or Dead Marine 

Mammals 

In addition, NMFS would require BP 

to notify NMFS’ Office of Protected 

Resources and NMFS’ Stranding 

Network within 48 hours of sighting an 

injured or dead marine mammal in the 

vicinity of marine survey operations. BP 

shall provide NMFS with the species or 

description of the animal(s), the 

condition of the animal(s) (including 

carcass condition if the animal is dead), 

location, time of first discovery, 

observed behaviors (if alive), and photo 

or video (if available). 

In the event that an injured or dead 

marine mammal is found by BP that is 

not in the vicinity of the proposed openwater marine survey program, BP would 

report the same information as listed 

above as soon as operationally feasible 

to NMFS. 

Estimated Take by Incidental 

Harassment 

Except with respect to certain 

activities not pertinent here, the MMPA 

defines ‘‘harassment’’ as: Any act of 

pursuit, torment, or annoyance which (i) 

has the potential to injure a marine 

mammal or marine mammal stock in the 

wild [Level A harassment]; or (ii) has 

the potential to disturb a marine 

mammal or marine mammal stock in the 

wild by causing disruption of behavioral 

patterns, including, but not limited to, 

migration, breathing, nursing, breeding, 

feeding, or sheltering [Level B 

harassment]. Only take by Level B 

behavioral harassment is anticipated as 

a result of the proposed open water 

marine survey program. Anticipated 

impacts to marine mammals are 

associated with noise propagation from 

the survey airgun(s) used in the shallow 

hazards survey. 

The full suite of potential impacts to 

marine mammals was described in 

detail in the ‘‘Potential Effects of the 

Specified Activity on Marine Mammals’’ 

section found earlier in this document. 

The potential effects of sound from the 

proposed open water marine survey 

programs might include one or more of 

the following: Masking of natural 

sounds; behavioral disturbance; nonauditory physical effects; and, at least in 

theory, temporary or permanent hearing 

impairment (Richardson et al. 1995). As 

discussed earlier in this document, the 

most common impact will likely be 

from behavioral disturbance, including 

avoidance of the ensonified area or 

changes in speed, direction, and/or 

diving profile of the animal. For reasons 

discussed previously in this document, 

hearing impairment (TTS and PTS) are 

highly unlikely to occur based on the 

proposed mitigation and monitoring 

measures that would preclude marine 

mammals being exposed to noise levels 

high enough to cause hearing 

impairment. 

For impulse sounds, such as those 

produced by airgun(s) used in the 

seismic survey, NMFS uses the 160 dB 

(rms) re 1 mPa isopleth to indicate the 

onset of Level B harassment. BP 

provided calculations for the 160- and 

120-dB isopleths produced by these 

activities and then used those isopleths 

to estimate takes by harassment. NMFS 

used the calculations to make the 

necessary MMPA preliminary findings. 

BP provided a full description of the 

methodology used to estimate takes by 

harassment in its IHA application (see 

ADDRESSES), which is also provided in 

the following sections. 

BP has requested an authorization to 

take 11 marine mammal species by 

Level B harassment. These 11 marine 

mammal species are: beluga whale 

(Delphinapterus leucas), killer whale 

(Orcinus orca), harbor porpoise 

(Phocoena phocoena), bowhead whale 

(Balaena mysticetus), gray whale 

(Eschrichtius robustus), humpback 

whale (Megaptera novaeangliae), minke 

whale (Balaenoptera acutorostrata), 

bearded seal (Erignathus barbatus), 

ringed seal (Phoca hispida), spotted seal 

(P. largha), and ribbon seal 

(Histriophoca fasciata). BP did not 

request take of narwhal because the 

occurrence of this species is extremely 

rare in the proposed action area, and it 

is very unlikely to be encountered 

during the BP’s proposed seismic 

surveys. 

Basis for Estimating ‘‘Take by 

Harassment’’ 

As stated previously, it is current 

NMFS practice to estimate take by Level 

A harassment for received levels above 

180 dB re 1mPa (rms) for cetaceans and 

190 dB re 1mPa (rms) for pinnipeds, and 

take by Level B harassment for all 

marine mammals under NMFS 

jurisdiction by impulse sounds at a 

received level above 160 dB re 1mPa 

(rms) and by non- impulse sounds at a 

received level above 120 dB re 1mPa 

(rms). However, not all animals are 

equally affected by the same received 

noise levels and, as described earlier, in 

most cases marine mammals are not 

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likely to be taken by Level A harassment 

(injury) when exposed to received levels 

higher than 180 dB for a brief period of 

time. 

For behavioral harassment, marine 

mammals will likely not show strong 

reactions (and in some cases any 

reaction) until sounds are much stronger 

than 160 or 120 dB (for impulse and 

continuous sounds, respectively). 

Southall et al. (2007) provide a severity 

scale for ranking observed behavioral 

responses of both free-ranging marine 

mammals and laboratory subjects to 

various types of anthropogenic sound 

(see Table 4 in Southall et al. (2007)). 

Tables 7, 9, and 11 in Southall et al. 

(2007) outline the numbers of lowfrequency cetaceans, mid-frequency 

cetaceans, and pinnipeds in water, 

respectively, reported as having 

behavioral responses to multi-pulses in 

10-dB received level increments. These 

tables illustrate that the more severe 

reactions did not occur until sounds 

were much higher than 160 dB re 1mPa 

(rms). 

As described earlier in the document, 

two main source vessels and a mini 

source vessel would be used to conduct 

the OBC seismic surveys in the Simpson 

Lagoon. Each of the main source vessels 

would be equipped with two subarrays 

containing eight 40 in3 airguns, with a 

total volume displacement of 640 in3. 

The mini source vessel would be 

equipped with one subarray containing 

eight 40 in3 airguns, with a total 

displacement volume of 320 in3. 

Modeling results show that the 160 dB 

isopleths for the 640 in3, 320 in3, and 

40 in3 airgun arrays inside the barrier 

islands are approximately 1,800 m, 

1,500 m, and 700 m from the source, 

respectively; the 160 dB isopleths for 

the 640 in3 and 40 in3 airgun arrays 

outside the barrier islands are 

approximately 5,500 m and 810 m from 

the source, respectively (Please see 

above for detailed description of the 

exclusion and disturbance zones). 

The radii associated with received 

sound levels of 160 dB re 1 mPa (rms) 

or higher are used to calculate the 

number of potential marine mammal 

‘‘exposures’’ to airgun sounds. The 

potential number of each species that 

might be exposed to received pulsed 

sound levels of ≥160 dB re 1 mPa (rms) 

is calculated by multiplying the 

expected species density with the 

anticipated area to be ensonified to that 

level during airgun operations. 

Bowhead and beluga whales are 

migrating through the area, so every 

encounter likely involves a new 

individual. Although seal species are 

also known to cover large distances, 

they are expected to linger longer within 

a certain area, and so one individual 

might be exposed multiple times. 

The area expected to be ensonified 

was determined by entering the seismic 

survey lines into a MapInfo Geographic 

Information System (GIS). GIS was then 

used to identify the relevant areas by 

‘‘drawing’’ the applicable 160-dB buffer 

of the 640 in3 array around each seismic 

source line and calculating the total area 

within the buffers. This was done for 

the survey area outside the barrier 

islands and inside the barrier islands 

separately. The area ensonified with 

pulsed sound levels of ≥160 dB re 1 mPa 

(rms) from airgun operations outside the 

barrier islands is estimated as 197.5 mi2

(512 km2) and from airgun operations 

inside the barrier islands 105 mi2 (272 

km2). 

Summer density (see below) estimates 

of marine mammals will be applied to 

all (100%) survey effort outside the 

barrier islands and to 60% survey effort 

inside the barrier islands. Fall densities 

are not applied to the outside barrier 

islands survey effort, since no survey 

effort is planned after August 25. Fall 

densities are applied to 100% survey 

effort inside the barrier islands activity, 

because some of the source lines will be 

rerun in order to image the full fold area 

adequately. 

Marine Mammal Density Estimates 

Because most cetacean species show a 

distinct seasonal distribution, density 

estimates for the central Beaufort Sea 

have been derived for the summer 

period (covering July and August) and 

the fall period (covering September and 

October). Animal densities encountered 

in the Beaufort Sea during both of these 

time periods will further depend on the 

presence of ice. However, if ice cover 

within or close to the seismic survey 

area is more than approximately 10%, 

seismic survey activities may not start 

or be halted. Cetacean and pinniped 

densities related to ice conditions are 

therefore not included in BP’s IHA 

application. Pinniped species in the 

Beaufort Sea do not show a distinct 

seasonal distribution during the period 

July-early October and as such density 

estimates derived for seal species are 

used for both the summer and fall 

periods. 

In addition to seasonal variation in 

densities, spatial differentiation is an 

important factor for marine mammal 

densities, both in latitudinal and 

longitudinal gradient. Taking into 

account the size and location of the 

proposed seismic survey area and the 

associated area of influence, only the 

nearshore zone (defined as the area 

between the shoreline and the 50 m [164 

ft] bathymetry line) of the Beaufort Sea 

was considered to be relevant for the 

calculation of densities. 

Density estimates are based on best 

available scientific data. In cases where 

the best available data were collected in 

regions, habitats, or seasons that differ 

from the proposed survey activities, 

information from monitoring results 

collected in similar habitats, regions or 

seasons was used. Some sources from 

which densities were used include 

correction factors to account for 

perception and availability bias in the 

reported densities. Perception bias is 

associated with diminishing probability 

of sighting with increasing lateral 

distance from the trackline, where an 

animal is present at the surface but 

could be missed. Availability bias refers 

to the fact that the animal might be 

present but is not available at the 

surface. The uncorrected number of 

marine mammals observed is therefore 

always lower than the actual numbers 

present. Unfortunately, for most marine 

mammals not enough information is 

available to calculate these two 

correction factors. The density estimates 

provided in the BP’s IHA request are 

therefore based on uncorrected data, 

unless mentioned otherwise. 

Because the available density data is 

not always representative for the area of 

interest, and correction factors were not 

always known, there is some 

uncertainty in the data and assumptions 

used in the density calculations. To 

provide allowance for these 

uncertainties, maximum density 

estimates have been provided in 

addition to average density estimates. 

The marine mammal densities 

presented are believed to be close to, 

and in most cases higher than, the 

densities that are expected to be 

encountered during the proposed 

survey. 

(1) Cetacean Densities 

Beluga Whale: Summer beluga 

density estimates for the Alaskan 

Beaufort Sea are derived from aerial 

survey data over the period 1982–1986 

as analyzed by Moore et al. (2000b). 

During the summer season, beluga 

whales were observed mostly in 

continental slope habitat (water depths 

of 201–2,000 m [660–6562 ft]) and 

infrequently in inner shelf habitat (< 50 

m [164 ft]). Most applicable to the 

proposed OBC seismic survey are the 

data collected in water depths of less 

than 164 ft. Along 7,447 mi (11,985 km) 

of on-transect effort in July–August 

there were a total of nine beluga 

sightings (Moore et al. 2000). No 

correction was applied to this data for 

the purpose of this IHA request for two 

reasons: (1) All nine sightings were 

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observed offshore of the 164 ft (50 m) 

bathymetry line and the proposed 

survey, including the contour of the 160 

dB sound level, occurs in shallower 

water depths, and (2) the majority of 

beluga sightings occurred farther to the 

east and there were no sightings at the 

longitude of Simpson Lagoon Bay. A 

density of 0.0008 whales/km2 was used 

as the average summer density for 

beluga whales. 

Fall densities for beluga whales were 

calculated using data derived from 

Bowhead Whale Aerial Survey Project 

(BWASP) aerial surveys collected in 

2006–2008 (Clarke et al. 2011). 

Generally, beluga whales selected water 

on the outer shelf and slope with 

moderate to heavy ice during the 

westward migration, however, ice cover 

in the period 2006–2008 was relatively 

low compared to historical years and 

beluga whales were often observed in 

ice free waters. Based on aerial survey 

data (Moore et al. 2000, Clarke et al. 

2011) few beluga whales are expected to 

be encountered in the central part of the 

Beaufort Sea, especially shoreward of 

the barrier islands. 

The fall beluga whale density was 

calculated by using the total transect 

effort and number of belugas observed 

during fall of 2006, 2007, and 2008 

(Clarke et al. 2011). A value of 2.841 to 

correct for animals missed, and a value 

of 0.58 to correct for animals not 

available at the surface from Harwood et 

al. (1996) were applied to derive 

corrected density estimates. Transect 

effort in the fall of 2006 was 12,393 km 

during which a total of 525 belugas 

observed. A corrected density of 0.1038 

whales/km2 was derived from this data. 

In fall 2007, a total of 117 belugas were 

sighted along 6,294 km of transect effort, 

from which a corrected density of 

0.0455 whales/km2 was calculated. The 

density for 2008 was the lowest with 15 

belugas along 10,856 km of transect 

effort (corrected density of 0.0034 

whales/km2). The average value over 

these three years was 0.0545 whales/ 

km2. This was calculated by dividing 

the total number of belugas sighted with 

the total 2006–2008 transect effort and 

applying the correction factors. The 

2006 fall density was used as the 

maximum value. Because most sightings 

were observed offshore of the 50 m 

bathymetry line and the proposed 

survey takes place in water depths of 

less than 15 m (of which a majority 

inside the barrier islands), the densities 

used for the purpose of this IHA request 

were assumed to be 25% of the average 

density provided here. 

Bowhead Whale: Bowheads in the 

eastern Alaskan and Canadian Beaufort 

Sea occur in offshore habitats during the 

summer. Starting late August-early 

September whales are leaving their 

feeding grounds and migrate westward 

in shallower habitats during years with 

moderate and light ice-cover and in 

deeper waters in years with heavy icecover. During the summer period (July– 

August) relatively few bowhead whales 

are expected to be present in the 

nearshore zone of the central Beaufort 

Sea. Bowhead sightings become more 

common there when whales start their 

westward migration in August, with 

peak sighting rates occurring in 

September. 

The bowhead whale summer density 

estimates were derived from 2008 aerial 

survey data in Camden Bay (Christie et 

al. 2010) and the 2010 aerial survey in 

Harrison Bay (Brandon et al. 2011) 

conducted as part of a marine mammal 

monitoring program for seismic and 

shallow hazard surveys. Because these 

data sets cover the summer season 

(July–August) it was considered to be 

the most representative information 

available. The 2008 Camden Bay survey 

area covered water depths between 20– 

200 m. The average density over the 

period July 6–August 18 was estimated 

to be 0.009 whales/km2, and included 

correction factors from Thomas et al. 

(2002). This density was based on data 

collected on the three days that 

bowhead whales were sighted (July 7, 9, 

and 12), during periods without 

operational airguns. The 2010 Harrison 

Bay aerial survey covered the area just 

offshore of the barrier islands to 100 m 

water depth. The average density over 

the period July 16–August 13 was 0.004 

whales/km2, including correction 

factors from Thomas et al. (2002). This 

density was based on data collected 

before seismic operations started during 

which one bowhead was observed on 

August 3. For the purpose of this IHA 

request, the average summer density 

was derived from these two values 

(0.0065 whales/km2). 

The bowhead whale fall density 

estimates used in this IHA request are 

derived from the BWASP aerial surveys, 

which contain the best available and 

most current information of bowhead 

whale distribution and abundance in 

the Beaufort Sea. These surveys started 

in 1979 and have been repeated 

annually, resulting in a large multi-year 

dataset. Clarke and Ferguson (2010) 

present an update of this aerial survey 

effort, summarizing data from the period 

2000–2009, and comparing those with 

results from data prior to 2000. Since 

the Simpson Lagoon OBC seismic 

project takes place around 148° 

longitude in waters of less than 50 ft (15 

m), densities of bowhead whales 

provided by Clarke and Ferguson (2010) 

for the eastern Beaufort Sea (defined as 

east of 154° longitude) in the 0–20 m 

depth zone were considered to be most 

representative of the proposed survey 

area. Clarke and Ferguson (2010) 

reported 96 animals during 9,933 km of 

on transect aerial survey effort in 

September and 42 animals during 6,143 

km of on transect effort in October. 

Correction factors from Thomas et al. 

(2002) were applied to these numbers; 

this is a value of 2 to correct for animals 

available at the surface but not detected 

and a value of 0.07 for animals present 

but not available at the surface. This 

resulted in a density of 0.1381 whales/ 

km2 for September and 0.0977 whales/ 

km2 for October. The combined 

September-October value (0.1226 

whales/km2) is used as the average 

density and the September value as the 

maximum density. 

Other Cetacean Species: No densities 

have been estimated for gray whales and 

for cetacean species that are rare or 

extralimital to the Beaufort Sea 

(humpback whale, minke whale, killer 

whale, harbor porpoise, narwhal), 

because sightings of this animals have 

been very infrequent. Gray whales may 

be encountered in small numbers 

throughout the summer and fall, 

especially in the nearshore areas. Small 

numbers of harbor porpoises may be 

encountered as well. During an aerial 

survey offshore of Oliktok Point in 2008, 

just west of the proposed survey area, 

two harbor porpoises were sighted 

offshore of the barrier islands, one on 

August 25 and the other on September 

10 (Hauser et al. 2008). The first 

confirmed sighting of a humpback 

whale with calf was documented on 

August 1, 2007, about 54 mile (87 km) 

east of Point Barrow (Hashagen et al. 

2009), so an occasional sighting could 

occur. Therefore, for the purpose of this 

IHA request, BP requested that ‘‘takes’’ 

be authorized to cover chance 

encountering of these animals during 

the proposed seismic survey. 

(2) Pinniped Densities 

Pinnipeds in the polar regions are 

mostly associated with sea ice and most 

census methods count pinnipeds when 

they are hauled out on the ice. To 

account for the proportion of animals 

present but not hauled out (availability 

bias) or seals present on the ice but 

missed (detection bias), a correction 

factor should be applied to the ‘‘raw’’ 

counts. This correction factor is 

dependent on the behavior of each 

species. To estimate what proportion of 

ringed seals were generally visible 

resting on the sea ice, radio tags were 

placed on seals during spring 1999– 

2003 (Kelly et al. 2006). The probability 

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that seals were visible, derived from the 

satellite data, was applied to seal 

abundance data from past aerial surveys 

and indicated that the proportion of 

seals visible varied from less than 0.40 

to more than 0.75 between survey years. 

The environmental factors that are 

important in explaining the availability 

of seals to be counted were found to be 

time of day, date, wind speed, air 

temperature, and days from snow melt 

(Kelly et al. 2006). Besides the 

uncertainty in the correction factor, 

using counts of basking seals from 

spring surveys to predict seal 

abundance in the open-water period is 

further complicated by the fact that seal 

movements differ substantially between 

these two seasons (Kelly et al. 2010b). 

Data from nine ringed seals that were 

tracked from one subnivean period 

(early winter through mid-May or early 

June) to the next showed that ringed 

seals covered large distances during the 

open water foraging period (Kelly et al. 

2010b). Ringed seals tagged in 2011 

close to Barrow also show long distance 

travel during the open water season. 

To estimate densities for ringed, 

bearded and spotted seals, data were 

used from three surveys conducted as 

part of shallow water OBC seismic 

surveys in the Beaufort Sea (Harris et al. 

2001, Aerts et al. 2008, Hauser et al. 

2008). Habitat and survey specifics are 

very similar to the proposed survey, 

therefore these data were considered to 

be the more representative than basking 

seal densities from spring aerial survey 

data (e.g., Moulton et al. 2002, Frost et 

al. 2002, 2004). 

No distinction is made in density of 

pinnipeds between summer and autumn 

season. Also, no correction factors have 

been applied to the seal densities 

reported here. Instead, a multiplier was 

applied to the estimated densities to 

account for variability in seal 

abundance. 

Ringed seals are the most common 

seal species in the Beaufort Sea, 

followed by the bearded seal. Spotted 

seals also occur, specifically in the 

nearshore zone, but are not as frequently 

observed as the other two species. 

During the 1996 OBC survey, 92% of all 

seal species identified were ringed seals, 

7% bearded seals and 1% spotted seals 

(Harris et al. 2001). This 1996 survey 

occurred in two habitats, one about 19 

mile east of Prudhoe Bay near the 

McClure Islands, mainly inshore of the 

barrier islands in water depths of 10 to 

26 ft and the other 6 to 30 miles 

northwest of Prudhoe Bay, about 0 to 8 

mile offshore of the barrier islands in 

water depths of 10 to 56 ft (Harris et al. 

2001). Because it is often difficult to 

identify seals to species, a large 

proportion of seal sightings were 

unidentified in all three surveys. The 

total seal sighting rate was therefore 

used to calculate densities for each 

species, using the ratio of 92%, 7%, and 

1% for ringed, bearded and spotted 

seals as mentioned above. 

During the 1996 OBC survey (Harris et 

al. 2001) the sighting rate for all seals 

during periods when airguns were not 

operating was 0.63 seals/hour. The 

sighting rate during non- seismic 

periods was 0.046 seals/hour for the 

survey in Foggy Island Bay, just east of 

Prudhoe Bay (Aerts et al. 2008). The 

OBC survey that took place at Oliktok 

Point, adjacent to the proposed survey 

in Simpson Lagoon, recorded 0.0671 

seals/hour when airguns were not 

operating (Hauser et al. 2008). The 

survey effort in kilometers or miles is 

only reported for the survey at Oliktok 

Point. 

The total source line miles that will 

be travelled during the proposed OBC 

seismic survey is approximately 4,000 

miles (6,440 km). The average vessel 

speed during the survey will be ∼3 knots 

(or 3.4 miles/hour), calculated based on 

a 40 ft distance traveled during the 8- 

second shot interval. Applying the 

average vessel speed of 3.4 miles/hour, 

it will take about 1176 hours to 

complete data acquisition along these 

source lines, which is equivalent to 

about 49 days. The total number of seals 

expected to be observed in the area is 

741 (based on 0.63 seals/hour), 54 

(based on 0.046 seals/hour), and 79 

(based on 0.067 seals/hour). The average 

of these three values is 291 seals, and 

the maximum 741 seals. 

Ringed Seal: The average density for 

ringed seals is expected to be 0.0420 

seals/km2, based on a ratio of 92% and 

a total of 6,440 km [(291 × 0.92)/6,440)]. 

To account for variability in seal 

abundance the average density was 

multiplied by a factor 4. 

Bearded Seal: The average density for 

bearded seals is expected to be 0.0031 

seals/km2, based on a ratio of 7% and 

a total of 6,440 km [(291 × 0.07)/6,440)]. 

To account for variability in seal 

abundance the average density was 

multiplied by a factor 4. 

Spotted Seal: The average density for 

ringed seals is expected to be 0.0005 

seals/km2, based on a ratio of 1% and 

a total of 6,440 km [(291 × 0.01)/6,440)]. 

To account for variability in seal 

abundance the average density was 

multiplied by 4. 

Table 3 lists a summary of marine 

mammal densities used for calculating 

the estimated takes. 

TABLE 3—EXPECTED DENSITIES OF

MARINE MAMMALS IN THE SIMPSON

LAGOON SURVEY AREA

Species 

Summer 

densities 

(#/km2) 

Autumn 

densities 

(#/km2) 

Bowhead whale .... 0.0065 0.1226 

Beluga whale ........ 0.0008 0.0136 

Ringed seal ........... 0.1680 0.1680 

Bearded seal ........ 0.0124 0.0124 

Spotted seal .......... 0.0020 0.0020 

Potential Number of Takes by 

Harassment 

Numbers of marine mammals that 

might be present and potentially taken 

are summarized in Table 4 based on 

available data about mammal 

distribution and densities at different 

locations and times of the year as 

described above. 

Some of the animals estimated to be 

exposed, particularly migrating 

bowhead whales, might show avoidance 

reactions before being exposed to ≥160 

dB re 1 mPa (rms). Thus, these 

calculations actually estimate the 

number of individuals potentially 

exposed to ≥160 dB (rms) that would 

occur if there were no avoidance of the 

area ensonified to that level. 

For beluga whales and spotted seals 

that may form groups, additional takes 

were requested on top of the densitybased take calculation in the event a 

large group is encountered during the 

survey. For marine mammal species that 

are extralimital and for which no 

density estimates are available in the 

vicinity of the proposed project area 

(such as gray, humpback, minke, and 

killer whales, harbor porpoise, and 

ribbon seal), a small number of takes 

have been requested in case they are 

encountered (Table 4). 

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TABLE 4—ESTIMATES OF THE POSSIBLE NUMBERS OF MARINE MAMMALS TAKEN BY LEVEL B HARASSMENT (EXPOSED TO

≥160 DB RE 1 μPA (RMS)) DURING BP’S PROPOSED SEISMIC PROGRAM IN THE BEAUFORT SEAS, JULY–OCTOBER 2012 

Species 

Outside barrier 

islands 

Inside barrier islands 

Total estimated 

takes 

Summer Summer Autumn 

Bowhead whale ............................................................................... 3 1 33 37 

Beluga whale ................................................................................... 0 0 4 * 50 

Gray whale ....................................................................................... ............................ ............................ ............................ 3 

Humpback whale ............................................................................. ............................ ............................ ............................ 2 

Minke whale ..................................................................................... ............................ ............................ ............................ 2 

Killer whale ...................................................................................... ............................ ............................ ............................ 3 

Harbor porpoise ............................................................................... ............................ ............................ ............................ 3 

Ringed seal ...................................................................................... 60 19 32 111 

Bearded seal .................................................................................... 9 3 5 17 

Spotted seal ..................................................................................... 1 0 1 * 20 

Ribbon seal ...................................................................................... ............................ ............................ ............................ 3 

* Additional takes were requested in the event that a large group of beluga whales is encountered. 

Estimated Take Conclusions 

Cetaceans—Effects on cetaceans are 

generally expected to be restricted to 

avoidance of an area around the seismic 

survey and short-term changes in 

behavior, falling within the MMPA 

definition of ‘‘Level B harassment’’. 

Using the 160 dB criterion, the 

average estimates of the numbers of 

individual cetaceans exposed to sounds 

≥160 dB (rms) re 1 mPa represent varying 

proportions of the populations of each 

species in the Beaufort Sea and adjacent 

waters. For species listed as 

‘‘Endangered’’ under the ESA, the 

estimates include approximately 37 

bowheads. This number is 

approximately 0.24% of the BeringChukchi-Beaufort population of over 

15,232 assuming 3.4% annual 

population growth from the estimate of 

over 10,545 animals (Zeh and Punt 

2005). For other cetaceans that might 

occur in the vicinity of the Simpson 

Lagoon survey area, they also represent 

a very small proportion of their 

respective populations. The average 

estimates of the number of belugas (with 

additional takes to count for chance 

encounter of a large group) that might be 

exposed to ≥160 dB re 1 mPa is 50, 

which represents 0.13% of the Beaufort 

Sea population (or 1.35% of the Eastern 

Chukchi Sea population, or a mix 

between these two populations) of the 

beluga whales. In addition, the average 

estimates of gray, humpback, minke, 

and killer whales, and harbor porpoise 

that might be exposed to ≥160 dB re 1 

mPa are 3, 2, 2, 3,and 3. These numbers 

represent 0.02%, 0.21%, 0.20%, 0.96%, 

and 0.0062% of these species of their 

respective populations in the proposed 

action area. 

Seals—A few seal species are likely to 

be encountered in the study area, but 

ringed seal is by far the most abundant 

in this area. The average estimates of the 

numbers of individuals exposed to 

sounds at received levels ≥160 dB (rms) 

re 1 mPa during the proposed shallow 

hazards survey are as follows: ringed 

seals (111), bearded seals (17), spotted 

seals (20, with additional takes to count 

for chance encounter of a group), and 

ribbon seals (2). These numbers 

represent 0.05%, 0.01%, 0.03%, and 

0.0033% of Alaska stocks of ringed, 

bearded, spotted, and ribbon seals, 

respectively. 

Negligible Impact and Small Numbers 

Analysis and Preliminary 

Determination 

NMFS has defined ‘‘negligible 

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

impact resulting from the specified 

activity that cannot be reasonably 

expected to, and is not reasonably likely 

to, adversely affect the species or stock 

through effects on annual rates of 

recruitment or survival.’’ In making a 

negligible impact determination, NMFS 

considers a variety of factors, including 

but not limited to: (1) The number of 

anticipated mortalities; (2) the number 

and nature of anticipated injuries; (3) 

the number, nature, intensity, and 

duration of Level B harassment; and (4) 

the context in which the takes occur. 

No injuries or mortalities are 

anticipated to occur as a result of BP’s 

proposed 2012 OBC seismic survey in 

the Simpson Lagoon of the Alaskan 

Beaufort Sea, and none are proposed to 

be authorized. In addition, these surveys 

would use relatively small 640 in3

airgun arrays, which have much less 

acoustic power outputs compared to 

conventional airgun arrays with 

displacement volume in the range of 

thousands cubic inches. Additionally, 

the survey areas are in shallow waters, 

with approximately 42% of the survey 

area located inside the barrier islands 

(depth: 0–9 ft, or 0–3 m) and 33% 

located outside the barrier islands 

(depth: 3–45 ft, or 1–15 m), where 

horizontal sound propagation of low 

frequency airgun pulses is severely 

limited. For the seismic survey inside 

the barrier islands, the islands provide 

a natural barrier that would effectively 

reduce sound propagation out to the 

open ocean, if not completely eliminate 

its propagation. The modeled isopleths 

at 160 dB within the barrier islands is 

expected to be approximately 1.8 km, 

and 5.5 km outside barrier islands, from 

an airgun array of 640 in3 (see 

discussion earlier). Additionally, 

animals in the area are not expected to 

incur hearing impairment (i.e., TTS or 

PTS) or non-auditory physiological 

effects. Takes will be limited to Level B 

behavioral harassment. Although it is 

possible that some individuals of 

marine mammals may be exposed to 

sounds from the proposed seismic 

survey activities more than once, the 

expanse of these multi-exposures are 

expected to be less extensive since both 

the animals and the survey vessels will 

be moving constantly in and out of the 

survey areas. 

Most of the bowhead whales 

encountered during the summer will 

likely show overt disturbance 

(avoidance) only if they receive airgun 

sounds with levels ≥ 160 dB re 1 mPa. 

Odontocete reactions to seismic energy 

pulses are usually assumed to be limited 

to shorter distances from the airgun(s) 

than are those of mysticetes, probably in 

part because odontocete low-frequency 

hearing is assumed to be less sensitive 

than that of mysticetes. However, at 

least when in the Canadian Beaufort Sea 

in summer, belugas appear to be fairly 

responsive to seismic energy, with few 

being sighted within 6–12 mi (10–20 

km) of seismic vessels during aerial 

surveys (Miller et al. 2005). Belugas will 

likely occur in small numbers in the 

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Beaufort Sea during the survey period 

and few will likely be affected by the 

survey activity. In addition, due to the 

constant moving of the survey vessel, 

the duration of the noise exposure by 

cetaceans to seismic impulse would be 

brief. For the same reason, it is unlikely 

that any individual animal would be 

exposed to high received levels multiple 

times. 

Taking into account the mitigation 

measures that are planned, effects on 

cetaceans are generally expected to be 

restricted to avoidance of a limited area 

around the survey operation and shortterm changes in behavior, falling within 

the MMPA definition of ‘‘Level B 

harassment’’. The many reported cases 

of apparent tolerance by cetaceans of 

seismic exploration, vessel traffic, and 

some other human activities show that 

co-existence is possible. Mitigation 

measures such as controlled vessel 

speed, dedicated marine mammal 

observers, non-pursuit, and shut downs 

or power downs when marine mammals 

are seen within defined ranges will 

further reduce short-term reactions and 

minimize any effects on hearing 

sensitivity. In all cases, the effects are 

expected to be short-term, with no 

lasting biological consequence. 

Of the eleven marine mammal species 

likely to occur in the proposed marine 

survey area, only the bowhead and 

humpback whales are listed as 

endangered under the ESA. These 

species are also designated as 

‘‘depleted’’ under the MMPA. Despite 

these designations, the Bering-ChukchiBeaufort stock of bowheads has been 

increasing at a rate of 3.4 percent 

annually for nearly a decade (Allen and 

Angliss 2010). Additionally, during the 

2001 census, 121 calves were counted, 

which was the highest yet recorded. The 

calf count provides corroborating 

evidence for a healthy and increasing 

population (Allen and Angliss 2010). 

The occurrence of humpback whales in 

the proposed marine survey areas is 

considered very rare. There is no critical 

habitat designated in the U.S. Arctic for 

the bowhead, fin, and humpback whale. 

The Alaska stock of bearded seals, part 

of the Beringia distinct population 

segment (DPS), and the Arctic stock of 

ringed seals, have been proposed by 

NMFS for listing as threatened under 

the ESA (bearded seals: 75 FR 77496; 

December 10, 2011; ringed seal: 75 FR 

77476; December 10, 2011). None of the 

other species that may occur in the 

project area are listed as threatened or 

endangered under the ESA or 

designated as depleted under the 

MMPA. 

Potential impacts to marine mammal 

habitat were discussed previously in 

this document (see the ‘‘Anticipated 

Effects on Habitat’’ section). Although 

some disturbance is possible to food 

sources of marine mammals, the 

impacts are anticipated to be minor 

enough as to not affect rates of 

recruitment or survival of marine 

mammals in the area. Based on the vast 

size of the Arctic Ocean where feeding 

by marine mammals occurs versus the 

localized area of the marine survey 

activities, any missed feeding 

opportunities in the direct project area 

would be minor based on the fact that 

other feeding areas exist elsewhere. 

The estimated takes proposed to be 

authorized represent 0.13% of the 

Beaufort Sea population of 

approximately 39,258 beluga whales (or 

1.35% of the Eastern Chukchi Sea 

population of approximately 3,710 

beluga whales, or a mix of each 

population; Allen and Angliss 2010), 

1.59% of Aleutian Island and Bering Sea 

stock of approximately 314 killer 

whales, 0.004% of Bering Sea stock of 

approximately 48,215 harbor porpoises, 

0.02% of the Eastern North Pacific stock 

of approximately 19,126 gray whales, 

0.24% of the Bering- Chukchi-Beaufort 

population of 15,232 bowhead whales 

assuming 3.4 percent annual population 

growth from the estimate of 10,545 

animals (Zeh and Punt, 2005), 0.21% of 

the Western North Pacific stock of 

approximately 938 humpback whales, 

and 0.20% of the Alaska stock of 

approximately 1,003 minke whales. The 

take estimates presented for bearded, 

ringed, spotted, and ribbon seals 

represent 0.01, 0.05, 0.03, and 0.0033% 

of U.S. Arctic stocks of each species, 

respectively. These estimates represent 

the percentage of each species or stock 

that could be taken by Level B 

behavioral harassment if each animal is 

taken only once. In addition, the 

mitigation and monitoring measures 

(described previously in this document) 

proposed for inclusion in the IHA (if 

issued) are expected to reduce even 

further any potential disturbance to 

marine mammals. 

Based on the analysis contained 

herein of the likely effects of the 

specified activity on marine mammals 

and their habitat, and taking into 

consideration the implementation of the 

mitigation and monitoring measures, 

NMFS preliminarily finds that BP’s 

proposed 2012 OBC seismic survey in 

the Simpson Lagoon of the Alaskan 

Beaufort Sea may result in the 

incidental take of small numbers of 

marine mammals, by Level B 

harassment only, and that the total 

taking from the marine surveys will 

have a negligible impact on the affected 

species or stocks. 

Unmitigable Adverse Impact Analysis 

and Preliminary Determination 

NMFS has preliminarily determined 

that BP’s proposed 2012 OBC seismic 

survey in the Beaufort Sea will not have 

an unmitigable adverse impact on the 

availability of species or stocks for 

taking for subsistence uses. This 

preliminary determination is supported 

by information contained in this 

document and BP’s CAA and draft POC. 

BP has adopted a spatial and temporal 

strategy for its Simpson Lagoon 

operations that should minimize 

impacts to subsistence hunters. 

Specifically, the BP’s proposed Simpson 

Lagoon OBC seismic survey would 

occur between July and October open 

water season, and would terminate its 

operations outside the barrier islands 

after August 25 before the fall bowhead 

whale hunt. Due to the timing of the 

project and the distance from the 

surrounding communities 

(approximately 35 miles northeast from 

Nuiqsut, 35 miles west from Cross 

Island, 150 miles west from Kaktovik 

and 180 miles east from Barrow), it is 

anticipated to have no effects on spring 

harvesting and little or no effects on the 

occasional summer harvest of beluga 

whale, subsistence seal hunts (ringed 

and spotted seals are primarily 

harvested in winter while bearded seals 

are hunted during July–September in 

the Beaufort Sea), or the fall bowhead 

hunt. 

In addition, based on the measures 

described in BP’s Draft POC and CAA, 

the proposed mitigation and monitoring 

measures (described earlier in this 

document), and the project design itself, 

NMFS has determined preliminarily 

that there will not be an unmitigable 

adverse impact on subsistence uses from 

BP’s OBC seismic survey in the 

Simpson Lagoon of the Beaufort Sea. 

Proposed Incidental Harassment 

Authorization 

This section contains a draft of the 

IHA itself. The wording contained in 

this section is proposed for inclusion in 

the IHA (if issued). 

(1) This Authorization is valid from 

July 1, 2012, through October 30, 2012. 

(2) This Authorization is valid only 

for activities associated with open-water 

OBC seismic surveys and related 

activities in the Beaufort Sea. The 

specific areas where BP’s surveys will 

be conducted are within the Simpson 

Lagoon Area, Beaufort Sea, Alaska, as 

shown in Figure 1.2 of BP’s IHA 

application. 

(3)(a) The species authorized for 

incidental harassment takings, Level B 

harassment only, are: Beluga whales 

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Federal Register / Vol. 77, No. 84 / Tuesday, May 1, 2012 / Notices 25853 

(Delphinapterus leucas); harbor 

porpoises (Phocoena phocoena); killer 

whales (Orcinus orca); bowhead whales 

(Balaena mysticetus); gray whales 

(Eschrichtius robustus); humpback 

whales (Megaptera novaeangliae); 

minke whales (Balaenoptera 

acutorostrata); bearded seals 

(Erignathus barbatus); spotted seals 

(Phoca largha); ringed seals (P. hispida); 

and ribbon seals (P. fasciata). 

(3)(b) The authorization for taking by 

harassment is limited to the following 

acoustic sources and from the following 

activities: 

(i) 640 in3 airgun arrays for each of the 

two main source vessels; 

(ii) 320 in3 airgun array for one mini 

source vessels; and 

(ii) Vessel activities related to the 

OBC seismic surveys. 

(3)(c) The taking of any marine 

mammal in a manner prohibited under 

this Authorization must be reported 

within 24 hours of the taking to the 

Alaska Regional Administrator (907– 

586–7221) or his designee in Anchorage 

(907–271–3023), National Marine 

Fisheries Service (NMFS) and the Chief 

of the Permits and Conservation 

Division, Office of Protected Resources, 

NMFS, at (301) 427–8401, or his 

designee (301–427–8418). 

(4) The holder of this Authorization 

must notify the Chief of the Permits and 

Conservation Division, Office of 

Protected Resources, at least 48 hours 

prior to the start of collecting seismic 

data (unless constrained by the date of 

issuance of this Authorization in which 

case notification shall be made as soon 

as possible). 

(5) Prohibitions 

(a) The taking, by incidental 

harassment only, is limited to the 

species listed under condition 3(a) 

above and by the numbers listed in 

Table 1 (attached). The taking by Level 

A harassment, injury or death of these 

species or the taking by harassment, 

injury or death of any other species of 

marine mammal is prohibited and may 

result in the modification, suspension, 

or revocation of this Authorization. 

(b) The taking of any marine mammal 

is prohibited whenever the required 

source vessel protected species 

observers (PSOs), required by condition 

7(a)(i), are not onboard in conformance 

with condition 7(a)(i) of this 

Authorization. 

(6) Mitigation 

(a) Seismic Operation Mitigation: 

(i) Whenever a marine mammal is 

detected outside the exclusion zone 

radius and based on its position and 

motion relative to the ship track is likely 

to enter the exclusion radius, calculate 

and implement an alternative ship 

speed or track or de-energize the airgun 

array, as described in condition 6(b)(iv) 

below. 

(ii) Exclusion Zones: 

(A) Establish and monitor with 

trained PSOs a preliminary exclusion 

zone for cetaceans surrounding the 

airgun array on the source vessel where 

the received level would be 180 dB re 

1 mPa rms. For purposes of the field 

verification test, described in condition 

7(b), this radius is estimated to be 750 

m (2,460 ft) from the seismic source for 

the 640 in3 airgun arrays, 480 m (1,574 

ft) for the 320 in3 airgun array, and 59 

m (194 ft) for a single 40 in3 airgun for 

surveys conducted inside barrier 

islands; and 950 m (3,116 ft) for 640 in3

airgun arrays and less than 50 m (164 

ft) for a single 40 in3 airgun for surveys 

conducted outside barrier islands. 

(B) Establish and monitor with trained 

PSOs a preliminary exclusion zone for 

pinnipeds surrounding the airgun array 

on the source vessel where the received 

level would be 190 dB re 1 mPa rms. For 

purposes of the field verification test 

described in condition 7(b), this radius 

is estimated to be 310 m (1,017 ft) from 

the seismic source for the 640 in3 airgun 

arrays, 160 m (525 ft) for the 320 in3

airgun array, and 16 m (53 ft) for the 

single 40 in3 airgun for surveys 

conducted inside barrier islands; and 

120 m (394 ft) for 640 in3 airgun arrays 

and less than 50 m (164 ft) for a single 

40 in3 airgun for surveys conducted 

outside barrier islands. 

(C) A 120-dB vessel monitoring zone 

for four or more bowhead cow/calf pairs 

will be established and monitored after 

August 25, 2012, from a monitoring 

vessel outside the barrier islands during 

all daytime seismic surveys, as 

described in 7(a)(iv) below. For 

purposes of the field verification test 

described in condition 7(b), this radius 

is estimated to be 6,400 m (20,992 ft) 

from the seismic source for the 640 in3

airgun arrays, 5,700 m (18,700 ft) for the 

320 in3 airgun array, and 3,700 m 

(12,140 ft) for the single 40 in3 airgun 

for surveys conducted inside barrier 

islands. 

(D) Immediately upon completion of 

data analysis of the field verification 

measurements required under condition 

7(b) below, the new 180-dB and 190-dB 

marine mammal exclusion zones shall 

be established based on the sound 

source verification. 

(iii) Ramp-up: 

(A) A ramp up, following a cold start, 

can be applied if the exclusion zone has 

been free of marine mammals for a 

consecutive 30-minute period. The 

entire exclusion zone must have been 

visible during these 30 minutes. If the 

entire exclusion zone is not visible, then 

ramp up from a cold start cannot begin. 

(B) Ramp up procedures from a cold 

start shall be delayed if a marine 

mammal is sighted within the exclusion 

zone during the 30-minute period prior 

to the ramp up. The delay shall last 

until the marine mammal(s) has been 

observed to leave the exclusion zone or 

until the animal(s) is not sighted for at 

least 15 or 30 minutes. The 15 minutes 

applies to small toothed whales and 

pinnipeds, while a 30 minute 

observation period applies to baleen 

whales and large toothed whales. 

(C) A ramp up, following a shutdown, 

can be applied if the marine mammal(s) 

for which the shutdown occurred has 

been observed to leave the exclusion 

zone or until the animal(s) is not sighted 

for at least 15 minutes (small toothed 

whales and pinnipeds) or 30 minutes 

(baleen whales and large toothed 

whales). 

(D) If, for any reason, electrical power 

to the airgun array has been 

discontinued for a period of 10 minutes 

or more, ramp-up procedures shall be 

implemented. Only if the PSO watch 

has been suspended, a 30-minute 

clearance of the exclusion zone is 

required prior to commencing ramp-up. 

Discontinuation of airgun activity for 

less than 10 minutes does not require a 

ramp-up. 

(E) The seismic operator and PSOs 

shall maintain records of the times 

when ramp-ups start and when the 

airgun arrays reach full power. 

(iv) Power-down/Shutdown: 

(A) The airgun array shall be 

immediately powered down whenever a 

marine mammal is sighted approaching 

close to or within the applicable 

exclusion zone of the full array, but is 

outside the applicable exclusion zone of 

the single mitigation airgun. 

(B) If a marine mammal is already 

within the exclusion zone when first 

detected, the airguns shall be powered 

down immediately. 

(C) Following a power-down, ramp up 

to the full airgun array shall not resume 

until the marine mammal has cleared 

the exclusion zone. The animal will be 

considered to have cleared the 

exclusion zone if it is visually observed 

to have left the exclusion zone of the 

full array, or has not been seen within 

the zone for 15 minutes (pinnipeds or 

small toothed whales) or 30 minutes 

(baleen whales or large toothed whales). 

(D) If a marine mammal is sighted 

within or about to enter the 190 or 180 

dB (rms) applicable exclusion zone of 

the single mitigation airgun, the airgun 

array shall be shutdown. 

(E) Whenever more than four or more 

bowhead cow/calf pairs are observed 

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25854 Federal Register / Vol. 77, No. 84 / Tuesday, May 1, 2012 / Notices 

within or entering the 120 dB 

disturbance zone the lead PSO on the 

monitoring vessel will immediately 

contact the lead PSO on the source 

vessel, who will ensure prompt 

implementation of airgun power downs 

or shut-downs. 

(F) Airgun activity shall not resume 

until the marine mammal has cleared 

the exclusion zone of the full array. The 

animal will be considered to have 

cleared the exclusion zone as described 

above under ramp up procedures. 

(iv) Poor Visibility Conditions: 

(A) If during foggy conditions, heavy 

snow or rain, or darkness, the full 180 

dB exclusion zone is not visible, the 

airguns cannot commence a ramp-up 

procedure from a full shut-down. 

(B) If one or more airguns have been 

operational before nightfall or before the 

onset of poor visibility conditions, they 

can remain operational throughout the 

night or poor visibility conditions. In 

this case ramp-up procedures can be 

initiated, even though the exclusion 

zone may not be visible, on the 

assumption that marine mammals will 

be alerted by the sounds from the single 

airgun and have moved away. 

(C) When seismic survey is not 

underway, BP shall not keep an airgun 

(the so called ‘‘mitigation gun’’ in past 

IHAs) firing for long periods of time 

during darkness or other periods of poor 

visibility on the assumption that marine 

mammals will be alerted by the sounds 

from the single airgun so that a cold 

start with pre survey monitoring could 

be avoided. 

(b) Vessel and Helicopter Movement 

Mitigation: 

(i) Avoid concentrations or groups of 

whales by all vessels under the 

direction of BP. Operators of support 

vessels should, at all times, conduct 

their activities at the maximum distance 

possible from such concentrations of 

whales. 

(ii) Transit and cable laying vessels 

shall be operated at speeds necessary to 

ensure no physical contact with whales 

occurs. If any barge or transit vessel 

approaches within 1.6 km (1 mi) of 

observed bowhead whales, except when 

providing emergency assistance to 

whalers or in other emergency 

situations, the vessel operator will take 

reasonable precautions to avoid 

potential interaction with the bowhead 

whales by taking one or more of the 

following actions, as appropriate: 

(A) Reducing vessel speed to less than 

5 knots within 300 yards (900 feet or 

274 m) of the whale(s); 

(B) Steering around the whale(s) if 

possible; 

(C) Operating the vessel(s) in such a 

way as to avoid separating members of 

a group of whales from other members 

of the group; 

(D) Operating the vessel(s) to avoid 

causing a whale to make multiple 

changes in direction; and 

(E) Checking the waters immediately 

adjacent to the vessel(s) to ensure that 

no whales will be injured when the 

propellers are engaged. 

(iii) When weather conditions require, 

such as when visibility drops, adjust 

vessel speed accordingly to avoid the 

likelihood of injury to whales. 

(iv) In the event that any aircraft (such 

as helicopters) are used to support the 

planned survey, the mitigation measures 

below would apply: 

(A) Under no circumstances, other 

than an emergency, shall aircraft be 

operated at an altitude lower than 1,000 

feet above sea level (ASL) when within 

0.3 mile (0.5 km) of groups of whales. 

(B) Helicopters shall not hover or 

circle above or within 0.3 mile (0.5 km) 

of groups of whales. 

(c) Mitigation Measures for 

Subsistence Activities: 

(i) No seismic surveys with airgun 

operations shall be conducted in the 

area north of the barrier islands after 25 

August, 2012. 

(ii) Fully implement the following 

measures, consistent with the 2012 

Conflict Avoidance Agreement (CAA) 

and Plan of Cooperation (COP), in order 

to avoid having an unmitigable adverse 

impact on the availability of marine 

mammal species or stocks for taking for 

subsistence uses: 

(A) For the purposes of reducing or 

eliminating conflicts between 

subsistence whaling activities and BP’s 

survey program, the holder of this 

Authorization will participate with 

other operators in the Communication 

and Call Centers (Com-Center) Program. 

The Com-Centers will be operated 24 

hours/day during the 2012 fall 

subsistence bowhead whale hunt. 

(B) BP shall routinely call the ComCenter according to the established 

protocol in the CAA while in the 

Beaufort Sea. 

(C) The appropriate Com-Center shall 

be notified if there is any significant 

change in plans, such as an 

unannounced start-up of operations or 

significant deviations from announced 

course. 

(D) Upon notification by a ComCenter operator of an at-sea emergency, 

the holder of this Authorization shall 

provide such assistance as necessary to 

prevent the loss of life, if conditions 

allow the holder of this Authorization to 

safely do so. 

(E) Post-season Review: Following the 

end of the fall 2012 bowhead whale 

subsistence hunt and prior to the 2013 

pre-season introduction meetings, BP 

shall offer to the Alaska Eskimo 

Whaling Commission (AEWC) Chairman 

to host a joint meeting with all whaling 

captains of the Villages of Nuiqsut, 

Kaktovik, and Barrow, the Marine 

Mammal Observer/Inupiat 

Communicators stations on BP’s vessels 

in the Beaufort Sea, and with the 

Chairman and Executive Director of the 

AEWC, at a mutually agreed upon time 

and place on the North Slope of Alaska, 

to review the results of the 2012 

Beaufort Sea open-water season, unless 

it is agreed by all designated individuals 

or their representatives that such a 

meeting is not necessary. 

(7) Monitoring: 

(a) Vessel Monitoring: 

(i) The holder of this Authorization 

must designate biologically-trained, onsite individuals (PSOs) to be onboard 

the source vessel and monitoring vessels 

outside the barrier islands, who are 

approved in advance by NMFS, to 

conduct the visual monitoring programs 

required under this Authorization and 

to record the effects of seismic surveys 

and the resulting noise on marine 

mammals. 

(A) PSO teams shall consist of Inupiat 

observers and experienced field 

biologists. An experienced field crew 

leader will supervise the PSO team 

onboard the survey vessel. New 

observers shall be paired with 

experienced observers to avoid 

situations where lack of experience 

impairs the quality of observations. 

(B) Crew leaders and most other 

biologists serving as observers in 2012 

will be individuals with experience as 

observers during recent seismic or 

shallow hazards monitoring projects in 

Alaska, the Canadian Beaufort, or other 

offshore areas in recent years. 

(C) PSOs shall complete a two or 

three-day training session on marine 

mammal monitoring, to be conducted 

shortly before the anticipated start of the 

2012 open-water season. The training 

session(s) will be conducted by 

qualified marine mammalogists with 

extensive crew-leader experience during 

previous vessel-based monitoring 

programs. A marine mammal observers’ 

handbook, adapted for the specifics of 

the planned survey program, will be 

reviewed as part of the training. 

(D) If there are Alaska Native PSOs, 

the PSO training that is conducted prior 

to the start of the survey activities shall 

be conducted with both Alaska Native 

PSOs and biologist PSOs being trained 

at the same time in the same room. 

There shall not be separate training 

courses for the different PSOs. 

(E) Crew members should not be used 

as primary PSOs because they have 

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other duties and generally do not have 

the same level of expertise, experience, 

or training as PSOs, but they could be 

stationed on the fantail of the vessel to 

observe the near field, especially the 

area around the airgun array and 

implement a rampdown or shutdown if 

a marine mammal enters the safety zone 

(or exclusion zone). 

(F) If crew members are to be used as 

PSOs, they shall go through some basic 

training consistent with the functions 

they will be asked to perform. The best 

approach would be for crew members 

and PSOs to go through the same 

training together. 

(G) PSOs shall be trained using visual 

aids (e.g., videos, photos), to help them 

identify the species that they are likely 

to encounter in the conditions under 

which the animals will likely be seen. 

(H) BP shall train its PSOs to follow 

a scanning schedule that consistently 

distributes scanning effort according to 

the purpose and need for observations. 

For example, the schedule might call for 

60% of scanning effort to be directed 

toward the near field and 40% at the far 

field. All PSOs should follow the same 

schedule to ensure consistency in their 

scanning efforts. 

(I) PSOs shall be trained in 

documenting the behaviors of marine 

mammals. PSOs should simply record 

the primary behavioral state (i.e., 

traveling, socializing, feeding, resting, 

approaching or moving away from 

vessels) and relative location of the 

observed marine mammals. 

(ii) To the extent possible, PSOs 

should be on duty for four (4) 

consecutive hours or less, although 

more than one four-hour shift per day is 

acceptable. 

(iii) Monitoring is to be conducted by 

the PSOs onboard the active seismic 

vessel, to (A) ensure that no marine 

mammals enter the appropriate 

exclusion zone whenever the seismic 

acoustic sources are on, and (B) to 

record marine mammal activity as 

described in condition 7(a)(vii) below. 

Two PSOs will be present on each 

seismic source vessel. At least one PSO 

shall monitor for marine mammals at 

any time during daylight hours. 

(iv) Monitoring vessel based surveys 

outside the barrier islands will be 

conducted up to 3 days per week, 

weather depending, after August 25, 

2012, and continue until the end of the 

data acquisition period. One PSO will 

be present on the monitoring vessel. The 

monitoring effort will be aided by the 

skipper of the monitoring vessel. 

(v) At all times, the crew must be 

instructed to keep watch for marine 

mammals. If any are sighted, the bridge 

watch-stander must immediately notify 

the PSO(s) on-watch. If a marine 

mammal is within or closely 

approaching its designated exclusion 

zone, the seismic acoustic sources must 

be immediately powered down or shut 

down (in accordance with condition 

6(a)(iv) above). 

(vi) Observations by the PSOs on 

marine mammal presence and activity 

will begin a minimum of 30 minutes 

prior to the estimated time that the 

seismic source is to be turned on and/ 

or ramped up. 

(vii) All marine mammal observations 

and any airgun power-down, shut-down 

and ramp-up will be recorded in a 

standardized format. Data will be 

entered into a custom database using a 

notebook computer. The accuracy of the 

data entry will be verified by 

computerized validity data checks as 

the data are entered and by subsequent 

manual checking of the database after 

each day. These procedures will allow 

initial summaries of data to be prepared 

during and shortly after the field 

program, and will facilitate transfer of 

the data to statistical, graphical, or other 

programs for further processing and 

archiving. 

(viii) Monitoring shall consist of 

recording: (A) The species, group size, 

age/size/sex categories (if determinable), 

the general behavioral activity, heading 

(if consistent), bearing and distance 

from seismic vessel, sighting cue, 

behavioral pace, and apparent reaction 

of all marine mammals seen near the 

seismic vessel and/or its airgun array 

(e.g., none, avoidance, approach, 

paralleling, etc); (B) the time, location, 

heading, speed, and activity of the 

vessel (shooting or not), along with sea 

state, visibility, cloud cover and sun 

glare at (I) any time a marine mammal 

is sighted (including pinnipeds hauled 

out on barrier islands), (II) at the start 

and end of each watch, and (III) during 

a watch (whenever there is a change in 

one or more variable); (C) the 

identification of all vessels that are 

visible within 5 km of the seismic vessel 

whenever a marine mammal is sighted, 

and the time observed, bearing, 

distance, heading, speed and activity of 

the other vessel(s); (D) any identifiable 

marine mammal behavioral response 

(sighting data should be collected in a 

manner that will not detract from the 

PSO’s ability to detect marine 

mammals); (E) any adjustments made to 

operating procedures; and (F) visibility 

during observation periods so that total 

estimates of take can be corrected 

accordingly. 

(ix) BP shall work with its observers 

to develop a means for recording data 

that does not reduce observation time 

significantly. 

(x) PSOs shall use the best possible 

positions for observing (e.g., outside and 

as high on the vessel as possible), taking 

into account weather and other working 

conditions. PSOs shall carefully 

document visibility during observation 

periods so that total estimates of take 

can be corrected accordingly. 

(xi) PSOs shall scan systematically 

with the unaided eye and 7 x 50 reticle 

binoculars, supplemented with 20 x 60 

image-stabilized Zeiss Binoculars or 

Fujinon 25 x 150 ‘‘Big-eye’’ binoculars 

and night-vision equipment 

(‘‘Generation 3’’) when needed. 

(xii) PSOs shall attempt to maximize 

the time spent looking at the water and 

guarding the exclusion radii. They shall 

avoid the tendency to spend too much 

time evaluating animal behavior or 

entering data on forms, both of which 

detract from their primary purpose of 

monitoring the exclusion zone. 

(xiii) Night-vision equipment 

(Generation 3 binocular image 

intensifiers, or equivalent units) shall be 

available for use during low light hours. 

(xiv) PSOs shall understand the 

importance of classifying marine 

mammals as ‘‘unknown’’ or 

‘‘unidentified’’ if they cannot identify 

the animals to species with confidence. 

In those cases, they shall note any 

information that might aid in the 

identification of the marine mammal 

sighted. For example, for an 

unidentified mysticete whale, the 

observers should record whether the 

animal had a dorsal fin. 

(xv) Additional details about 

unidentified marine mammal sightings, 

such as ‘‘blow only’’, mysticete with (or 

without) a dorsal fin, ‘‘seal splash’’, etc., 

shall be recorded. 

(xvi) PSOs on monitoring vessels 

outside barrier islands shall also 

monitor for the presence and behavior 

of marine mammals in the offshore area 

projected to be exposed to seismic 

sounds. 

(b) Sound Source Verification: Using 

a hydrophone system, the holder of this 

Authorization is required to conduct 

sound source verification tests for 

seismic airgun array(s) and vessels that 

are involved in the OBC seismic 

surveys. 

(i) Sound source verification shall 

consist of distances where broadside 

and endfire directions at which 

broadband received levels reach 190, 

180, 170, 160, and 120 dB re 1 mPa (rms) 

for the airgun array(s). The 

configurations of airgun arrays shall 

include at least the full array and the 

operation of a single source that will be 

used during power downs. 

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(ii) The test results shall be reported 

to NMFS within 5 days of completing 

the test. 

(c) Acoustic Monitoring: 

(i) BP shall use the offshore 

monitoring vessel to monitor 

(periodically) the propagation of airgun 

sounds from within the lagoon into 

offshore areas during its marine 

mammal survey using a dipping 

hydrophone. 

(ii) BP shall use additional acoustic 

monitoring with bottom mounted 

recorders to verify noise propagation 

model results. Recorders shall be 

deployed throughout the entire duration 

of the seismic survey. 

(8) Data Analysis and Presentation in 

Reports: 

(a) Estimation of potential takes or 

exposures shall be improved for times 

with low visibility (such as during fog 

or darkness) through interpolation or 

possibly using a probability approach. 

Those data could be used to interpolate 

possible takes during periods of 

restricted visibility. 

(b) Water depth should be 

continuously recorded by the vessel and 

for each marine mammal sighting. Water 

depth should be accounted for in the 

analysis of take estimates. 

(c) BP shall be very clear in their 

report about what periods are 

considered ‘‘non-seismic’’ for analyses. 

(d) BP shall examine data from 

Bowhead Whale Aerial Survey Program 

and other such programs to assess 

possible impacts from their seismic 

survey. 

(e) To better assess impacts to marine 

mammals, data analysis shall be 

separated into periods when a seismic 

airgun array (or a single mitigation 

airgun) is operating and when it is not. 

Final and comprehensive reports to 

NMFS should summarize and plot: 

(i) Data for periods when a seismic 

array is active and when it is not; and 

(ii) The respective predicted received 

sound conditions over fairly large areas 

(tens of km) around operations. 

(f) To help evaluate the effectiveness 

of PSOs and more effectively estimate 

take, if appropriate data are available, 

BP shall perform analysis of sightability 

curves (detection functions) for 

distance-based analyses. 

(g) To better understand the potential 

effects of oil and gas activities on 

marine mammals and to facilitate 

integration among companies and other 

researchers, the following data should 

be obtained and provided electronically 

in the 90-day report: 

(i) The location and time of each 

aerial or vessel-based sighting or 

acoustic detection; 

(ii) Position of the sighting or acoustic 

detection relative to ongoing operations 

(i.e., distance from sightings to seismic 

operation, drilling ship, support ship, 

etc.), if known; 

(iii) The nature of activities at the 

time (e.g., seismic on/off); 

(iv) Any identifiable marine mammal 

behavioral response (sighting data 

should be collected in a manner that 

will not detract from the PSO’s ability 

to detect marine mammals); and 

(v) Adjustments made to operating 

procedures. 

(h) BP should improve take estimates 

and statistical inference into effects of 

the activities by incorporating the 

following measures: 

(i) Reported results from all 

hypothesis tests should include 

estimates of the associated statistical 

power when practicable. 

(ii) Estimate and report uncertainty in 

all take estimates. Uncertainty could be 

expressed by the presentation of 

confidence limits, a minimummaximum, posterior probability 

distribution, etc.; the exact approach 

would be selected based on the 

sampling method and data available. 

(9) Reporting: 

(a) Sound Source Verification Report: 

A report on the preliminary results of 

the sound source verification 

measurements, including the measured 

190, 180, 160, and 120 dB (rms) radii of 

the airgun sources, shall be submitted 

within 14 days after collection of those 

measurements at the start of the field 

season. This report will specify the 

distances of the exclusion zones that 

were adopted for the survey. 

(b) Seismic Vessel Monitoring 

Program: A draft report will be 

submitted to the Director, Office of 

Protected Resources, NMFS, within 90 

days after the end of BP’s 2012 open 

water OBC seismic surveys in the 

Beaufort Seas. The report will describe 

in detail: 

(i) Summaries of monitoring effort 

(e.g., total hours, total distances, and 

marine mammal distribution through 

the study period, accounting for sea 

state and other factors affecting 

visibility and detectability of marine 

mammals); 

(ii) Analyses of the effects of various 

factors influencing detectability of 

marine mammals (e.g., sea state, number 

of observers, and fog/glare); 

(iii) Species composition, occurrence, 

and distribution of marine mammal 

sightings, including date, water depth, 

numbers, age/size/gender categories (if 

determinable), group sizes, and ice 

cover; 

(iv) To better assess impacts to marine 

mammals, data analysis should be 

separated into periods when a seismic 

airgun array (or a single airgun) is 

operating and when it is not. Final and 

comprehensive reports to NMFS should 

summarize and plot: (A) Data for 

periods when a seismic array is active 

and when it is not; and (B) The 

respective predicted received sound 

conditions over fairly large areas (tens of 

km) around operations. 

(v) Sighting rates of marine mammals 

during periods with and without airgun 

activities (and other variables that could 

affect detectability), such as: (A) Initial 

sighting distances versus airgun activity 

state; (B) closest point of approach 

versus airgun activity state; (C) observed 

behaviors and types of movements 

versus airgun activity state; (D) numbers 

of sightings/individuals seen versus 

airgun activity state; (E) distribution 

around the survey vessel versus airgun 

activity state; and (F) estimates of take 

by harassment. 

(vi) Reported results from all 

hypothesis tests should include 

estimates of the associated statistical 

power when practicable. 

(vii) Estimate and report uncertainty 

in all take estimates. Uncertainty could 

be expressed by the presentation of 

confidence limits, a minimummaximum, posterior probability 

distribution, etc.; the exact approach 

would be selected based on the 

sampling method and data available. 

(viii) The report should clearly 

compare authorized takes to the level of 

actual estimated takes. 

(c) The draft report will be subject to 

review and comment by NMFS. Any 

recommendations made by NMFS must 

be addressed in the final report prior to 

acceptance by NMFS. The draft report 

will be considered the final report for 

this activity under this Authorization if 

NMFS has not provided comments and 

recommendations within 90 days of 

receipt of the draft report. 

(10) (a) In the unanticipated event that 

survey operations clearly cause the take 

of a marine mammal in a manner 

prohibited by this Authorization, such 

as an injury (Level A harassment), 

serious injury or mortality (e.g., shipstrike, gear interaction, and/or 

entanglement), BP shall immediately 

cease survey operations and 

immediately report the incident to the 

Supervisor of Incidental Take Program, 

Permits and Conservation Division, 

Office of Protected Resources, NMFS, at 

301–427–8401 and/or by email to 

Jolie.Harrison@noaa.gov and 

Shane.Guan@noaa.gov and the Alaska 

Regional Stranding Coordinators 

(Aleria.Jensen@noaa.gov and 

Barbara.Mahoney@noaa.gov). The 

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report must include the following 

information: 

(i) Time, date, and location (latitude/ 

longitude) of the incident; 

(ii) The name and type of vessel 

involved; 

(iii) The vessel’s speed during and 

leading up to the incident; 

(iv) Description of the incident; 

(v) Status of all sound source use in 

the 24 hours preceding the incident; 

(vi) Water depth; 

(vii) Environmental conditions (e.g., 

wind speed and direction, Beaufort sea 

state, cloud cover, and visibility); 

(viii) Description of marine mammal 

observations in the 24 hours preceding 

the incident; 

(ix) Species identification or 

description of the animal(s) involved; 

(x) The fate of the animal(s); and 

(xi) Photographs or video footage of 

the animal (if equipment is available). 

Activities shall not resume until 

NMFS is able to review the 

circumstances of the prohibited take. 

NMFS shall work with BP to determine 

what is necessary to minimize the 

likelihood of further prohibited take and 

ensure MMPA compliance. BP may not 

resume their activities until notified by 

NMFS via letter, email, or telephone. 

(b) In the event that BP discovers an 

injured or dead marine mammal, and 

the lead PSO determines that the cause 

of the injury or death is unknown and 

the death is relatively recent (i.e., in less 

than a moderate state of decomposition 

as described in the next paragraph), BP 

will immediately report the incident to 

the Supervisor of the Incidental Take 

Program, Permits and Conservation 

Division, Office of Protected Resources, 

NMFS, at 301–427–8401, and/or by 

email to Jolie.Harrison@noaa.gov and 

Shane.Guan@noaa.gov and the NMFS 

Alaska Stranding Hotline (1–877–925– 

7773) and/or by email to the Alaska 

Regional Stranding Coordinators 

(Aleria.Jensen@noaa.gov and 

Barabara.Mahoney@noaa.gov). The 

report must include the same 

information identified in Condition 

10(a) above. Activities may continue 

while NMFS reviews the circumstances 

of the incident. NMFS will work with 

BP to determine whether modifications 

in the activities are appropriate. 

(c) In the event that BP discovers an 

injured or dead marine mammal, and 

the lead PSO determines that the injury 

or death is not associated with or related 

to the activities authorized in Condition 

3 of this Authorization (e.g., previously 

wounded animal, carcass with moderate 

to advanced decomposition, or 

scavenger damage), BP shall report the 

incident to the Supervisor of the 

Incidental Take Program, Permits and 

Conservation Division, Office of 

Protected Resources, NMFS, at 301– 

427–8401, and/or by email to 

Jolie.Harrison@noaa.gov and 

Shane.Guan@noaa.gov and the NMFS 

Alaska Stranding Hotline (1–877–925– 

7773) and/or by email to the Alaska 

Regional Stranding Coordinators 

(Aleria.Jensen@noaa.gov and 

Barbara.Mahoney@noaa.gov), within 24 

hours of the discovery. BP shall provide 

photographs or video footage (if 

available) or other documentation of the 

stranded animal sighting to NMFS and 

the Marine Mammal Stranding Network. 

BP can continue its operations under 

such a case. 

(11) Activities related to the 

monitoring described in this 

Authorization do not require a separate 

scientific research permit issued under 

section 104 of the Marine Mammal 

Protection Act. 

(12) The Conflict Avoidance 

Agreement and the Plan of Cooperation 

outlining the steps that will be taken to 

cooperate and communicate with the 

native communities to ensure the 

availability of marine mammals for 

subsistence uses, must be implemented. 

(13) This Authorization may be 

modified, suspended, or withdrawn if 

the holder fails to abide by the 

conditions prescribed herein or if the 

authorized taking is having more than a 

negligible impact on the species or stock 

of affected marine mammals, or if there 

is an unmitigable adverse impact on the 

availability of such species or stocks for 

subsistence uses. 

(14) A copy of this Authorization and 

the Incidental Take Statement must be 

in the possession of each seismic vessel 

operator taking marine mammals under 

the authority of this Incidental 

Harassment Authorization. 

(15) BP is required to comply with the 

Terms and Conditions of the Incidental 

Take Statement corresponding to NMFS’ 

Biological Opinion. 

Endangered Species Act (ESA) 

The bowhead whale and humpback 

whale are the only marine mammal 

species currently listed as endangered 

under the ESA that could occur during 

BP’s proposed OBC seismic survey 

during the Arctic open-water season. 

The Beringia DPS of the Alaska stock of 

bearded seals and the Arctic stock of 

ringed seals are proposed for listing as 

threatened under the ESA. Final 

decisions concerning the listing of these 

species are expected to be made in 

summer 2012. 

NMFS’ Permits and Conservation 

Division has initiated consultation with 

NMFS’ Protected Resources Division 

under section 7 of the ESA on the 

issuance of an IHA to BP under section 

101(a)(5)(D) of the MMPA for this 

activity. Consultation will be concluded 

prior to a determination on the issuance 

of an IHA. 

National Environmental Policy Act 

(NEPA) 

NMFS is currently preparing an 

Environmental Assessment, pursuant to 

NEPA, to determine whether or not this 

proposed activity may have a significant 

effect on the human environment. This 

analysis will be completed prior to the 

issuance or denial of the IHA. 

Proposed Authorization 

As a result of these preliminary 

determinations, NMFS proposes to 

authorize the take of marine mammals 

incidental to BP’s 2012 OBC seismic 

survey in the Simpson Lagoon of the 

Alaskan Beaufort Sea, provided the 

previously mentioned mitigation, 

monitoring, and reporting requirements 

are incorporated. 

Dated: April 25, 2012. 

Helen Golde, 

Acting Director, Office of Protected Resources, 

National Marine Fisheries Service. 

[FR Doc. 2012–10386 Filed 4–30–12; 8:45 am] 

BILLING CODE 3510–22–P 

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