[Federal Register Volume 76, Number 129 (Wednesday, July 6, 2011)]
[Proposed Rules]
[Pages 39706-39747]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2011-16327]



[[Page 39705]]

Vol. 76

Wednesday,

No. 129

July 6, 2011

Part V





Department of Commerce





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National Oceanic and Atmospheric Administration





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50 CFR Part 217





Taking and Importing Marine Mammals; Taking Marine Mammals Incidental 
to Operation of Offshore Oil and Gas Facilities in the U.S. Beaufort 
Sea; Proposed Rule

  Federal Register / Vol. 76 , No. 129 / Wednesday, July 6, 2011 / 
Proposed Rules  

[[Page 39706]]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

50 CFR Part 217

[Docket No. 100217096-1312-01]
RIN 0648-AY63


Taking and Importing Marine Mammals; Taking Marine Mammals 
Incidental to Operation of Offshore Oil and Gas Facilities in the U.S. 
Beaufort Sea

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

ACTION: Proposed rule; request for comments.

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SUMMARY: NMFS has received a request from BP Exploration (Alaska) Inc. 
(BP) for authorization for the take of marine mammals incidental to 
operation of offshore oil and gas facilities in the U.S. Beaufort Sea, 
Alaska, for the period 2011-2016. Pursuant to the Marine Mammal 
Protection Act (MMPA), NMFS is proposing to issue regulations to govern 
that take and requesting information, suggestions, and comments on 
these proposed regulations. These regulations, if issued, would include 
required mitigation measures to ensure the least practicable adverse 
impact on the affected marine mammal species and stocks.

DATES: Comments and information must be received no later than August 
5, 2011.

ADDRESSES: You may submit comments, identified by 0648-AY63, by any one 
of the following methods:
     Electronic Submissions: Submit all electronic public 
comments via the Federal eRulemaking Portal http://www.regulations.gov.
     Hand delivery or mailing of paper, disk, or CD-ROM 
comments should be addressed to Michael Payne, Chief, Permits, 
Conservation and Education Division, Office of Protected Resources, 
National Marine Fisheries Service, 1315 East-West Highway, Silver 
Spring, MD 20910.
    Comments regarding any aspect of the collection of information 
requirement contained in this proposed rule should be sent to NMFS via 
one of the means stated here and to the Office of Information and 
Regulatory Affairs, NEOB-10202, Office of Management and Budget (OMB), 
Attn: Desk Office, Washington, DC 20503, [email protected].
    Instructions: All comments received are a part of the public record 
and will generally be posted to http://www.regulations.gov 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.
    NMFS will accept anonymous comments (enter N/A in the required 
fields if you wish to remain anonymous). Attachments to electronic 
comments will be accepted in Microsoft Word, Excel, WordPerfect, or 
Adobe PDF file formats only.

FOR FURTHER INFORMATION CONTACT: Candace Nachman, Office of Protected 
Resources, NMFS, (301) 713-2289, ext. 156, or Brad Smith, Alaska 
Region, NMFS, (907) 271-3023.

SUPPLEMENTARY INFORMATION:

Availability

    A copy of BP's application may be obtained by writing to the 
address specified above (see ADDRESSES), calling the contact listed 
above (see FOR FURTHER INFORMATION CONTACT), or visiting the Internet 
at: http://www.nmfs.noaa.gov/pr/permits/incidental.htm. To help NMFS 
process and review comments more efficiently, please use only one 
method to submit comments.

Background

    Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 et seq.) 
direct the Secretary of Commerce (Secretary) to allow, upon request, 
the incidental, but not intentional taking of marine mammals by U.S. 
citizens who engage in a specified activity (other than commercial 
fishing) during periods of not more than five consecutive years each if 
certain findings are made and regulations are issued or, if the taking 
is limited to harassment, notice of a proposed authorization is 
provided to the public for review.
    Authorization shall be granted if NMFS finds that the taking will 
have a negligible impact on the species or stock(s), will not have an 
unmitigable adverse impact on the availability of the species or 
stock(s) for subsistence uses, and if the permissible methods of taking 
and requirements pertaining to the mitigation, monitoring and reporting 
of such taking are set forth.
    NMFS has defined ``negligible impact'' in 50 CFR 216.103 as:

    an impact resulting from the specified activity that cannot be 
reasonably expected to, and is not reasonably likely to, adversely 
affect the species or stock through effects on annual rates of 
recruitment or survival.

    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

    On November 6, 2009, NMFS received an application from BP 
requesting authorization for the take of six marine mammal species 
incidental to operation of the Northstar development in the Beaufort 
Sea, Alaska, over the course of 5 years, which would necessitate the 
promulgation of new five-year regulations. Construction of Northstar 
was completed in 2001. The proposed activities for 2011-2016 include a 
continuation of drilling, production, and emergency training operations 
but no construction or activities of similar intensity to those 
conducted between 1999 and 2001. The likely or possible impacts of the 
planned continuing operations at Northstar on marine mammals involve 
both non-acoustic and acoustic effects. Potential non-acoustic effects 
could result from the physical presence of personnel, structures and 
equipment, construction or maintenance activities, and the occurrence 
of oil spills. Petroleum development and associated activities in 
marine waters introduce sound into the environment, produced by island 
construction, maintenance, and drilling, as well as vehicles operating 
on the ice, vessels, aircraft, generators, production machinery, gas 
flaring, and camp operations. BP requests authorization to take 
individuals of three cetacean and three pinniped species by Level B 
Harassment. They are: Bowhead, gray, and beluga whales and ringed, 
bearded, and spotted seals. Further, BP requests authorization to take 
five individual ringed seals by injury or mortality annually over the 
course of the 5-year rule.

Description of the Specified Activity

Background on the Northstar Development Facility

    BP is currently producing oil from an offshore development in the 
Northstar Unit (see Figure 1 in BP's application). This development is 
the first in the Beaufort Sea that makes use of a subsea pipeline to 
transport oil to shore and

[[Page 39707]]

then into the Trans-Alaska Pipeline System. The Northstar facility was 
built in State of Alaska waters on the remnants of Seal Island 
approximately 6 mi (9.5 km) offshore from Point Storkersen, northwest 
of the Prudhoe Bay industrial complex, and 3 mi (5 km) seaward of the 
closest barrier island. It is located approximately 54 mi (87 km) 
northeast of Nuiqsut, an Inupiat community.
    The main facilities associated with Northstar include a gravel 
island work surface for drilling and oil production facilities and two 
pipelines connecting the island to the existing infrastructure at 
Prudhoe Bay. One pipeline transports crude oil to shore, and the second 
imports gas from Prudhoe Bay for gas injection at Northstar. Permanent 
living quarters and supporting oil production facilities are also 
located on the island.
    The construction of Northstar began in early 2000 and continued 
through 2001. BP states that activities with similar intensity to those 
that occurred during the construction phase between 2000 and 2001 are 
not planned or expected for any date within the 5-year period that 
would be governed by the proposed regulations (i.e., 2011-2016). Well 
drilling began on December 14, 2000, and oil production commenced on 
October 31, 2001. Construction and maintenance activities occurred 
annually on the protection barrier around Northstar due to ice and 
storm impacts. In August 2003, two barges made a total of 52 round-
trips to haul 30,000 cubic yards of gravel from West Dock for berm 
construction. Depending on the actual damage, repair and maintenance in 
the following years consisted of activities such as creating a moat for 
diver access, removing concrete blocks in areas that had sustained 
erosion and/or block damage, and installing a new layer of filter 
fabric. In 2008, BP installed large boulders at the NE corner of the 
barrier instead of replacing the lower concrete blocks that were 
removed during a storm.
    The planned well-drilling program for Northstar was completed in 
May 2004. Drilling activities to drill new wells, conduct well 
maintenance, and drill well side-tracks continued in 2006 (six wells), 
2007 (two wells), and 2008 (two wells). The drill rig was demobilized 
and removed from the island by barge during the 2010 open water period. 
Although future drilling is not specifically planned, drilling of 
additional wells or well work-over may be required at some time in the 
future. A more detailed description of past construction, drilling, and 
production activities at Northstar can be found in BP's application 
(see ADDRESSES).

Expected Activities in 2011-2016

    During the 5-year period from 2011-2016, BP intends to continue 
production and emergency training operations. As mentioned previously, 
drilling is not specifically planned for the 2011-2016 time period but 
may be required at some point in the future. The activities described 
next could occur at any time during the 5-year period. Table 2 in BP's 
application (see ADDRESSES) summarizes the vehicles and machinery used 
during BP's Northstar activities since the development of Northstar 
Island. Although all these activities are not planned to take place 
during the 2011-2016 operational phase, some of the equipment may be 
required to repair or replace existing structures or infrastructure on 
Northstar in the future.
(1) Transportation of Personnel, Equipment, and Supplies
    Transportation needs for the Northstar project include the ability 
to safely transport personnel, supplies, and equipment to and from the 
site during repairs or maintenance, drilling, and operations in an 
offshore environment. During proposed island renewal construction that 
may take place during the requested time period, quantities of pipes, 
vertical support members (i.e., posts that hold up terrestrial 
pipelines), gravel, and a heavy module will be transported to the site. 
Drilling operations require movement of pipe materials, chemicals, and 
other supplies to the island. During ongoing field operations, 
equipment and supplies will need to be transported to the site. All 
phases of construction, drilling, and operation require movement of 
personnel to and from the Northstar area.
    During the operations phase from 2002-2009, fewer ice roads were 
required compared to the construction phase (2000-2001). The future 
scope of ice road construction activities during ongoing production is 
expected to be similar to the post-construction period of 2002-2009. 
The locations, dimensions, and construction techniques of these ice 
roads are described in the multi-year final comprehensive report 
(Richardson [ed.], 2008). The presence of ice roads allows the use of 
standard vehicles such as pick-ups, SUVs, buses and trucks for 
transport of personnel and equipment to and from Northstar during the 
ice-covered period. Ice roads are planned to be constructed and used as 
a means of winter transportation for the duration of Northstar 
operations. The orientation of future ice roads is undetermined, but 
will not exceed the number of ice roads created during the winter of 
2000/2001.
    Barges and Alaska Clean Seas (ACS) vessels are used to transport 
personnel and equipment from the Prudhoe Bay area to Northstar during 
the open-water season, which extends from approximately mid- to late-
July through early to mid-October. Seagoing barges are used to 
transport large modules and other supplies and equipment during the 
construction period.
    Helicopter access to Northstar Island continues to be an important 
transportation option during break-up and freeze-up of the sea ice when 
wind, ice conditions, or other operational considerations prevent or 
limit hovercraft travel. Helicopters will be used for movement of 
personnel and supplies in the fall after freeze-up begins and vessel 
traffic is not possible but before ice roads have been constructed. 
Helicopters will also be used in the spring after ice roads are no 
longer safe for all-terrain vehicles (ATVs) but before enough open 
water is available for vessel traffic. Helicopters are also available 
for use at other times of year in emergency situations. Helicopters fly 
at an altitude of at least 1,000 ft (305 m), except for take-off, 
landing, and as dictated for safe aircraft operations. Designated 
flight paths are assigned to minimize potential disturbance to wildlife 
and subsistence users.
    The hovercraft is used to transport personnel and supplies during 
break-up and freeze-up periods to reduce helicopter use. BP intends to 
continue the use of the hovercraft in future years. Specifications of 
the hovercraft and sound characteristics are described in Richardson 
([ed.] 2008) and Blackwell and Greene (2005).
(2) Production Operations
    The process facilities for the Northstar project are primarily 
prefabricated sealift modules that were shipped to the island and 
installed in 2001. The operational aspects of the Northstar production 
facility include the following: Two diesel generators (designated 
emergency generators); three turbine generators for the power plant, 
operating at 50 percent duty cycle (i.e., only two will be operating at 
any one time); two high pressure turbine compressors; one low pressure 
flare; and one high pressure flare. Both flares are located on the 215 
ft (66 m) flare tower. Modules for the facility include permanent 
living quarters (i.e., housing, kitchen/dining, lavatories, medical, 
recreation, office, and laundry space), utility module (i.e., 
desalinization plant,

[[Page 39708]]

emergency power, and wastewater treatment plant), warehouse/shop 
module, communications module, diesel and potable water storage, and 
chemical storage. Operations have been continuing since oil production 
began on October 31, 2001 and are expected to continue beyond 2016.
(3) Drilling Operations
    The drilling rig and associated equipment was moved by barge to 
Northstar Island from Prudhoe Bay during the open-water season in 2000. 
Drilling began in December 2000 using power supplied by the installed 
gas line. The first well drilled was the Underground Injection Control 
well, which was commissioned for disposal of permitted muds and 
cuttings on January 26, 2001. After Northstar facilities were 
commissioned, drilling above reservoir depth resumed, while drilling 
below that depth is allowed only during the ice covered period. 
Although future drilling is not specifically planned during the 
requested time period for this proposed rule, drilling of additional 
wells or well work-over may be required at some time during 2011-2016.
(4) Pipeline Design, Inspection, and Maintenance
    The Northstar pipelines have been designed, installed, and 
monitored to assure safety and leak prevention. Pipeline monitoring and 
surveillance activities have been conducted since oil production began, 
and BP will conduct long-term monitoring of the pipeline system to 
assure design integrity and to detect any potential problems through 
the life of the Northstar development. The program will include visual 
inspections/aerial surveillance and pig (a gauging/cleaning device) 
inspections.
    The Northstar pipelines include the following measures to assure 
safety and leak prevention:
     Under the pipeline design specifications, the tops of the 
pipes are 6-8 ft (1.8-2.4 m) below the original seabed (this is 2 times 
the deepest measured ice gouge);
     The oil pipeline uses higher yield steel than required by 
design codes as applied to internal pressure (by a factor of over 2.5 
times). This adds weight and makes the pipe stronger. The 10-in (25.4-
cm) diameter Northstar oil pipeline has thicker walls than the 48-in 
(122-cm) diameter Trans-Alaska Pipeline;
     The pipelines are designed to bend without leaking in the 
event of ice keel impingement or the maximum predicted subsidence from 
permafrost thaw;
     The pipelines are coated on the outside and protected with 
anodes to prevent corrosion; and
     The shore transition is buried to protect against storms, 
ice pile-up, and coastal erosion. The shore transition valve pad is 
elevated and set back from the shoreline.
    A best-available-technology leak detection system is being used 
during operations to monitor for any potential leaks. The Northstar 
pipeline incorporates two independent, computational leak detection 
systems: (1) The Pressure Point Analysis (PPA) system, which detects a 
sudden loss of pressure in the pipeline; and (2) the mass balance leak 
detection system, which supplements the PPA. Furthermore, an 
independent hydrocarbon sensor, the LEOS leak detection system, located 
between the two pipelines, can detect hydrocarbon vapors and further 
supplements the other systems.
     Intelligent inspection pigs are used during operations to 
monitor pipe conditions and measure any changes.
     The line is constructed with no flanges, valves, or 
fittings in the subsea section to reduce the likelihood of equipment 
failure.
    During operations, BP conducts aerial forward looking infrared 
(FLIR) surveillance of the offshore and onshore pipeline corridors at 
least once per week (when conditions allow), to detect pipeline leaks. 
Pipeline isolation valves are inspected on a regular basis. In addition 
to FLIR observations/inspections, BP conducts a regular oil pipeline 
pig inspection program to assess continuing pipeline integrity. The 
LEOS Leak Detection System is used continuously to detect under-ice 
releases during the ice covered period.
    The pipelines are also monitored annually to determine any 
potential sources of damage along the pipeline route. The monitoring 
work has been conducted in two phases: (1) A helicopter-based 
reconnaissance of strudel drainage features in early June; and (2) a 
vessel-based survey program in late July and early August. During the 
vessel-based surveys, multi-beam, single-beam, and side scan sonar are 
used. These determine the locations and characteristics of ice gouges 
and strudel scour depressions in the sea bottom along the pipeline 
route and at additional selected sites where strudel drainage features 
have been observed. If strudel scour depressions are identified, 
additional gravel fill is placed in the open water season to maintain 
the sea bottom to original pipeline construction depth.
(5) Routine Repair and Maintenance
    Various routine repair and maintenance activities have occurred 
since the construction of Northstar. Examples of some of these 
activities include completion and repair of the island slope protection 
berm and well cellar retrofit repairs. Activities associated with these 
repairs or modifications are reported in the 1999-2004 final 
comprehensive report (Rodrigues and Williams, 2006) and since 2005 in 
the various Annual Reports (Rodrigues et al., 2006; Rodrigues and 
Richardson, 2007; Aerts and Rodrigues, 2008; Aerts, 2009). Some of 
these activities, such as repair of the island slope protection berm, 
were major repairs that involved the use of barges and heavy equipment, 
while others were smaller-scale repairs involving small pieces of 
equipment and hand operated tools. The berm surrounding the island is 
designed to break waves and ice movement before they contact the island 
work surface and is subjected to regular eroding action from these 
forces. The berm and sheet pile walls will require regular surveying 
and maintenance in the future. Potential repair and maintenance 
activities that are expected to occur at Northstar during the period 
2011-2016 include pile driving, traffic, gravel transport, dock 
construction and maintenance, diving and other activities similar to 
those that have occurred in the past.
(6) Emergency and Oil Spill Response Training
    Emergency and oil spill response training activities are conducted 
at various times throughout the year at Northstar. Oil spill drill 
exercises are conducted by ACS during both the ice-covered and open-
water periods. During the ice-covered periods, exercises are conducted 
for containment of oil in water and for detection of oil under ice. 
These spill drills have been conducted on mostly bottom-fast ice in an 
area 200 ft x 200 ft (61 m x 61 m) located just west of the island, 
using snow machines and ATVs. The spill drill includes the use of 
various types of equipment to cut ice slots or drill holes through the 
floating sea ice. Typically, the snow is cleared from the ice surface 
with a Bobcat loader and snow blower to allow access to the ice. Two 
portable generators are used to power light plants at the drill site. 
The locations and frequency of future spill drills or exercises will 
vary depending on the condition of the sea ice and training needs.
    ACS conducts spill response training activities during the open-
water season

[[Page 39709]]

during late July through early October. Vessels used as part of the 
training typically include Zodiacs, Kiwi Noreens, and Bay-class boats 
that range in length from 12-45 ft (3.7-13.7 m). Future exercises could 
include other vessels and equipment.
    ARKTOS amphibious emergency escape vehicles are stationed on 
Northstar Island. Each ARKTOS is capable of carrying 52 people. 
Training exercises with the ARKTOS are conducted monthly during the 
ice-covered period. ARKTOS training exercises are not conducted during 
the summer. Equipment and techniques used during oil spill response 
exercises are continually updated, and some variations relative to the 
activities described here are to be expected.
(7) Northstar Abandonment
    Detailed plans for the decommissioning of Northstar will be 
prepared near the end of field life, which will not occur during the 
period requested for these proposed regulations. For additional 
information on abandonment and decommissioning of the Northstar 
facility, refer to BP's application (see ADDRESSES).

Northstar Sound Characteristics

    During continuing production activities at Northstar, sounds and 
non-acoustic stimuli will be generated by vehicle traffic, vessel 
operations, helicopter operations, drilling, and general operations of 
oil and gas facilities (e.g., generator sounds and gas flaring). The 
sounds generated from transportation activities will be detectable 
underwater and/or in air some distance away from the area of activity. 
The distance will depend on the nature of the sound source, ambient 
noise conditions, and the sensitivity of the receptor. Take of marine 
mammals by Level B harassment incidental to the activities mentioned in 
this document could occur for the duration of these proposed 
regulations. The type and significance of the harassment is likely to 
depend on the species and activity of the animal at the time of 
reception of the stimulus, as well as the distance from the sound 
source and the level of the sound relative to ambient conditions.
(1) Construction Sounds
    Sounds associated with construction of Seal Island in 1982 were 
studied and described by Greene (1983a) and summarized in the previous 
petition for regulations submitted by BP (BPXA, 1999). Underwater and 
in-air sounds and iceborne vibrations of various activities associated 
with the final construction phases of Northstar were recorded in the 
winter of 2000-2002 (Greene et al., 2008). The main purpose of these 
measurements was to characterize the properties of island construction 
sounds and to use this information in assessing their possible impacts 
on wildlife. Activities recorded included ice augering, pumping sea 
water to flood the ice and build an ice road, a bulldozer plowing snow, 
a Ditchwitch cutting ice, trucks hauling gravel over an ice road to the 
island site, a backhoe trenching the sea bottom for a pipeline, and 
both vibratory and impact sheet pile driving (Greene et al., 2008). 
Table 5 in BP's application presents a summary of the levels of 
construction sounds and vibrations measured around the Northstar 
prospect.
    Ice road construction is difficult to separate into its individual 
components, as one or more bulldozers and several rolligons normally 
work concurrently. Of the construction activities reported, those 
related to ice road construction (bulldozers, augering and pumping) 
produced the least amount of sound, in all three media. The distance to 
median background for the strongest one-third octave bands for 
bulldozers, augering, and pumping was less than 1.24 mi (2 km) for 
underwater sounds, less than 0.62 mi (1 km) for in-air sounds, and less 
than 2.5 mi (4 km) for iceborne vibrations (see Table 5 in BP's 
application). Vibratory sheet pile driving produced the strongest 
sounds, with broadband underwater levels of 143 dB re 1 [micro]Pa at 
328 ft (100 m). Most of the sound energy was in a tone close to 25 Hz. 
Distances to background levels of underwater sounds (approximately 1.86 
mi [3 km]) were somewhat smaller than expected. Shepard et al. (2001) 
recorded sound near Northstar in April 2001 during construction and 
reported that the noisiest conditions occurred during sheet pile 
installation with a vibrating hammer. BP's estimates were 8-10 dB 
higher at 492 ft (150 m) and 5-8 dB lower at 1.24 mi (2 km) than the 
measurements by Shepard et al. (2001). Greene et al. (2008) describes 
sound levels during impact sheet pile driving. However, satisfactory 
recordings for this activity were only obtained at one station 2,395 ft 
(730 m) from the sheet pile driven into the island. The maximum peak 
pressure recorded on the hydrophone was 136.1 dB re 1 [micro]Pa and 
141.1 dB re 1 [micro]Pa on the geophone (Greene et al., 2008).
(2) Operational Sounds
    Drilling operations started in December 2000 and were the first 
sound-producing activities associated with the operational phase at 
Northstar. The four principal operations that occur during drilling are 
drilling itself, tripping (extracting and lowering the drillstring), 
cleaning, and well-logging (lowering instruments on a cable down the 
hole). Drilling activities can be categorized as non-continuous sounds, 
i.e., they contribute to Northstar sounds intermittently. Other non-
continuous sounds are those from heavy equipment operation for snow 
removal, berm maintenance, and island surface maintenance. Sounds from 
occasional movements of a ``pig'' through the pipeline may also 
propagate into the marine or nearshore environment.
    Sounds from generators, process operations (e.g., flaring, seawater 
treatment, oil processing, gas injection), and island lighting are more 
continuous and contribute to the operational sounds from Northstar. 
Drilling and operational sounds underwater, in air, and of ice-borne 
vibrations were obtained at Northstar Island and are summarized here 
and in a bit more detail in BP's application (Blackwell et al., 2004b; 
Blackwell and Greene, 2006).
    Drilling--During the ice covered seasons from 1999 to 2002, 
drilling sounds were measured and readily identifiable underwater, with 
a marked increase in received levels at 60-250 Hz and 700-1400 Hz 
relative to no-drilling times. The higher-frequency peak, which was 
distinct enough to be used as a drilling ``signature'', was clearly 
detectible 3.1 mi (5 km) from the drill rig, but had fallen to 
background values by 5.8 mi (9.4 km). Distances at which background 
levels were reached were defined as the distance beyond which broadband 
levels remained constant with increasing distance from the source. 
Sound pressure levels of island production with and without drilling 
activities measured at approximately 1,640 ft (500 m) from Northstar 
are similar, with most of the sound energy below 100 Hz. The broadband 
(10-10,000 Hz) level was approximately 2 dB higher during drilling than 
without, but relatively low in both cases (99 vs. 97 dB re 1 [micro]Pa; 
Blackwell and Greene, 2006).
    In air, drilling sounds were not distinguishable from overall 
island sounds based on spectral characteristics or on broadband levels 
(Blackwell et al., 2004b). A similar result was found for recordings 
from geophones: broadband levels of iceborne vibrations with or without 
drilling were indistinguishable (Blackwell et al., 2004b). Thus, 
airborne sounds and iceborne vibrations were not strong enough during 
drilling to have much influence on overall Northstar sound, in contrast 
to underwater

[[Page 39710]]

sounds, which were higher during drilling (Blackwell and Greene, 2006).
    Richardson et al. (1995b) summarized then-available data by stating 
that sounds associated with drilling activities vary considerably, 
depending on the nature of the ongoing operations and the type of 
drilling platform (island, ship, etc.). Underwater sound associated 
with drilling from natural barrier islands or an artificial island 
built mainly of gravel is generally weak and is inaudible at ranges 
beyond several kilometers. The results from the Northstar monitoring 
work in more recent years are generally consistent with the earlier 
evidence.
    Other Operational Sounds: Ice-covered Season--Both with and without 
drilling, underwater broadband levels recorded north of the island 
during the ice-covered season were similar with and without production 
(Blackwell et al., 2004b). Although the broadband underwater levels did 
not seem to be affected appreciably by production activities, a peak at 
125-160 Hz could be related to production. This peak was no longer 
detectable 3.1 mi (5 km) from the island, either with or without 
simultaneous drilling (Blackwell et al., 2004b).
    Other Operational Sounds: Open-water Season--Underwater and in-air 
production sounds from Northstar Island were recorded and characterized 
during nine open-water seasons from 2000 to 2008 (Blackwell and Greene, 
2006; Blackwell et al., 2009). Island activity sounds recorded during 
2000-2003 included construction of the island, installation of 
facilities, a large sealift transported by several barges and 
associated Ocean, River, and Point Class tugs, conversion of power 
generation from diesel-powered generators to Solar gas turbines, 
drilling, production, and reconstruction of an underwater berm for 
protection against ice. From 2003-2008 island activities mainly 
consisted of production related sounds and maintenance activities of 
the protection barrier. During the open water season, vessels were the 
main contributors to the underwater sound field at Northstar (Blackwell 
and Greene, 2006). Vessel noise is discussed in the next subsection.
    During both the construction phase in 2000 and the drilling and 
production phase, island sounds underwater reached background values at 
distances of 1.2-2.5 mi (2-4 km; Blackwell and Greene, 2006). For each 
year, percentile levels of broadband sound (maximum, 95th, 50th, and 
5th percentile, and minimum) were computed over the entire field 
season. The range of broadband levels recorded over 2001-2008 for all 
percentiles is 80.8-141 dB re 1 [micro]Pa. The maximum levels are 
mainly determined by the presence of vessels and can be governed by one 
specific event. The 95th percentile represents the sound level 
generated at Northstar during 95% of the time. From 2004 to 2008 these 
levels ranged from 110 to 119.5 dB re 1 [micro]Pa at approximately 0.3 
mi (450 m) from Northstar. Much of the variation in received levels was 
dependent on sea state, which is correlated with wind speed. The lowest 
sound levels in the time series are indicative of the quietest times in 
the water near the island and generally correspond to times with low 
wind speeds. Conversely, times of high wind speed usually correspond to 
increased broadband levels in the directional seafloor acoustic 
recorder (DASAR) record (Blackwell et al., 2009). The short-term 
variability in broadband sound levels in 2008 was higher than in 
previous years. This was attributed to the presence of a new type of 
impulsive sound on the records of the near-island DASARs, referred to 
as ``pops''. Bearings pointed to the northeastern part of Northstar 
Island, but to date the source is not known. Pops were broadband in 
nature, of short duration (approximately 0.05 s), and with received 
sound pressure levels at the near-island DASAR ranging from 107 to 144 
dB re 1 [mu]Pa. This sound was also present on the 2009 records, but 
the source remains unknown.
    Airborne sounds were recorded concurrently with the boat-based 
recordings in 2000-2003 (Blackwell and Greene, 2006). The strongest 
broadband airborne sounds were recorded approximately 985 ft (300 m) 
from Northstar Island in the presence of vessels, and reached 61-62 dBA 
re 20 [mu]Pa. These values are expressed as A-weighted levels on the 
scale normally used for in-air sounds. In-air sounds generally reached 
a minimum 0.6-2.5 mi (1-4 km) from the island, with or without the 
presence of boats.
(3) Transportation Sounds
    Sounds related to winter construction activities of Seal Island in 
1982 were reported by Greene (1983a) and information on this topic can 
be found in BP's 1999 application (BPXA, 1999). During the construction 
and operation of Northstar Island from 2000 to 2002, underwater sound 
from vehicles constructing and traveling along the ice road diminished 
to background levels at distances ranging from 2.9 to 5.9 mi (4.6 to 
9.5 km). In-air sound levels of these activities reached background 
levels at distances ranging from 328-1,969 ft (100-600 m; see Table 5 
in BP's application).
    Sounds and vibrations from vehicles traveling along an ice road 
constructed across the grounded sea ice and along Flaxman Island (a 
barrier Island east of Prudhoe Bay) were recorded in air and within 
artificially constructed polar bear dens in March 2002 (MacGillivray et 
al., 2003). Underwater recordings were not made. Sounds from vehicles 
traveling along the ice road were attenuated strongly by the snow cover 
of the artificial dens; broadband vehicle traffic noise was reduced by 
30-42 dB. Sound also diminished with increasing distance from the 
station. Most vehicle noise was indistinguishable from background 
(ambient) noise at 1,640 ft (500 m), although some vehicles were 
detectable to more than 1.2 mi (2,000 m). Ground vibrations (measured 
as velocity) were undetectable for most vehicles at a distance of 328 
ft (100 m) but were detectable to 656 ft (200 m) for a H[auml]gglunds 
tracked vehicle (MacGillivray et al., 2003).
    Helicopters were used for personnel and equipment transport to and 
from Northstar during the unstable ice periods in spring and fall. 
Helicopters flying to and from Northstar generally maintain straight-
line routes at altitudes of 1,000 ft (300 m) ASL, thereby limiting the 
received levels at and below the surface. Helicopter sounds contain 
numerous prominent tones at frequencies up to about 350 Hz, with the 
strongest measured tone at 20-22 Hz. Received peak sound levels of a 
Bell 212 passing over a hydrophone at an altitude of approximately 
1,000 ft (300 m), which is the minimum allowed altitude for the 
Northstar helicopter under normal operating conditions, varied between 
106 and 111 dB re 1 [mu]Pa at 30 and 59 ft (9 and 18 m) water depth 
(Greene, 1982, 1985). Harmonics of the main rotor and tail rotor 
usually dominate the sound from helicopters; however, many additional 
tones associated with the engines and other rotating parts are 
sometimes present (Patenaude et al., 2002).
    Under calm conditions, rotor and engine sounds are coupled into the 
water within a 26[deg] cone beneath the aircraft. Some of the sound 
transmits beyond the immediate area, and some sound enters the water 
outside the 26[deg] cone when the sea surface is rough. However, 
scattering and absorption limit lateral propagation in shallow water. 
For these reasons, helicopter and fixed-wing aircraft flyovers are not 
heard underwater for very long, especially when compared to how long 
they are heard in air as the aircraft approaches, passes and moves away

[[Page 39711]]

from an observer. Tones from helicopter traffic were detected 
underwater at a horizontal distance approximately 1,476 ft (450 m) from 
Northstar, but only during helicopter departures from Northstar 
(Blackwell et al., 2009). The duration of the detectable tones, when 
present, was short (20-50 s), and the received sound levels were weak, 
sometimes barely detectable. The lack of detectable tones during 65% of 
the investigated helicopter departures and arrivals supports the 
importance of the aircraft's path in determining whether tones will be 
detectable underwater. Helicopter tones were not detectable underwater 
at the most southern DASAR location approximately 4 mi (6.5 km) north 
of Northstar.
    Principally the crew boat, tugs, and self-propelled barges were the 
main contributors to the underwater sound field at Northstar during the 
construction and production periods (Blackwell and Greene, 2006). 
Vessel sounds are a concern due to the potential disturbance to marine 
mammals (Richardson et al., 1995b). Characteristics of underwater 
sounds from boats and vessels have been reported extensively, including 
specific measurements near Northstar (Greene and Moore, 1995; Blackwell 
and Greene, 2006). Broadband source levels for most small ships 
(lengths about 180-279 ft [55-85 m]) are approximately 160-180 dB re 1 
[mu]Pa. Both the crew boat and the tugs produced substantial broadband 
sound in the 50-2,000 Hz range, which could at least in part be 
accounted for by propeller cavitation (Ross, 1976). Several tones were 
also apparent in the vessel sounds, including one at 17.5 Hz, 
corresponding to the propeller blade rate of Ocean Class tugs. Two 
tones were identified for the crew boat: one at 52-55 Hz, which 
corresponds to the blade rate, and one at 22-26 Hz, which corresponds 
to a harmonic of the shaft rate.
    The presence of boats considerably expanded the distances to which 
Northstar-related sound was detectable. On days with average levels of 
background sounds, sounds from tug boats were detectable on offshore 
DASAR recordings to at least 13.4 mi (21.5 km) from Northstar 
(Blackwell et al., 2009). On other occasions, vessel sounds from crew 
boat, tugs, and self-propelled barges were often detectable underwater 
as much as approximately 18.6 mi (30 km) offshore (Blackwell and 
Greene, 2006). BP therefore looked into options to reduce vessel use. 
During the summer of 2003, a small, diesel-powered hovercraft (Griffon 
2000TD) was tested to transport crew and supplies between the mainland 
and Northstar Island. Acoustic measurements showed that the hovercraft 
was considerably quieter underwater than similar-sized conventional 
vessels (Blackwell and Greene, 2005). Received underwater broadband 
sound levels at 21.3 ft (6.5 m) from the hovercraft reached 133 and 131 
dB re 1 [mu]Pa for hydrophone depths 3 ft and 23 ft (1 m and 7 m), 
respectively. In-air unweighted and A-weighted broadband (10-10,000 Hz) 
levels reached 104 and 97 dB re 20 [mu]Pa, respectively. Use of the 
hovercraft for Northstar transport resulted in a decreased number of 
periods of elevated vessel noise in the acoustic records of the near-
island DASARs (Blackwell et al., 2009).

Description of Marine Mammals in the Area of the Specified Activity

    The Beaufort Sea supports a diverse assemblage of marine mammals, 
including: Bowhead, gray, beluga, killer, minke, and humpback whales; 
harbor porpoises; ringed, ribbon, spotted, and bearded seals; narwhals; 
polar bears; and walruses. The bowhead and humpback whales and polar 
bear are listed as ``endangered'' under the Endangered Species Act 
(ESA) and as depleted under the MMPA. Certain stocks or populations of 
gray, beluga, and killer whales and spotted seals are listed as 
endangered or are proposed for listing under the ESA; however, none of 
those stocks or populations occur in the proposed activity area. On 
December 10, 2010, NMFS published a notice of proposed threatened 
status for subspecies of the ringed seal (75 FR 77476) and a notice of 
proposed threatened and not warranted status for subspecies and 
distinct population segments of the bearded seal (75 FR 77496) in the 
Federal Register. Neither of these two ice seal species is considered 
depleted under the MMPA. Additionally, the ribbon seal is considered a 
``species of concern'' under the ESA. Both the walrus and the polar 
bear are managed by the U.S. Fish and Wildlife Service (USFWS) and are 
not considered further in this proposed rulemaking.
    Of the species mentioned here, the ones that are most likely to 
occur near the Northstar facility include: bowhead, gray, and beluga 
whales and ringed, bearded, and spotted seals. Ringed seals are year-
round residents in the Beaufort Sea and are anticipated to be the most 
frequently encountered species in the proposed project area. Bowhead 
whales are anticipated to be the most frequently encountered cetacean 
species in the proposed project area; however, their occurrence is not 
anticipated to be year-round. The most common time for bowheads to 
occur near Northstar is during the fall migration westward through the 
Beaufort Sea, which typically occurs from late August through October 
each year.
    Other marine mammal species that have been observed in the Beaufort 
Sea but are uncommon or rarely identified in the project area include 
harbor porpoise, narwhal, killer, minke, and humpback whales, and 
ribbon seals. These species could occur in the project area, but each 
of these species is uncommon or rare in the area and relatively few 
encounters with these species are expected during BP's activities. The 
narwhal occurs in Canadian waters and occasionally in the Beaufort Sea, 
but it is rare there and is not expected to be encountered. There are 
scattered records of narwhal in Alaskan waters, including reports by 
subsistence hunters, where the species is considered extralimital 
(Reeves et al., 2002). Point Barrow, Alaska, is the approximate 
northeastern extent of the harbor porpoise's regular range (Suydam and 
George, 1992), though there are extralimital records east to the mouth 
of the Mackenzie River in the Northwest Territories, Canada, and recent 
sightings in the Beaufort Sea in the vicinity of Prudhoe Bay during 
surveys in 2007 and 2008 (Christie et al., 2009). Monnett and Treacy 
(2005) did not report any harbor porpoise sightings during aerial 
surveys in the Beaufort Sea from 2002 through 2004. Humpback and minke 
whales have recently been sighted in the Chukchi Sea but very rarely in 
the Beaufort Sea. Greene et al. (2007) reported and photographed a 
humpback whale cow/calf pair east of Barrow near Smith Bay in 2007, 
which is the first known occurrence of humpbacks in the Beaufort Sea. 
Savarese et al. (2009) reported one minke whale sighting in the 
Beaufort Sea in 2007 and 2008. Ribbon seals do not normally occur in 
the Beaufort Sea; however, two ribbon seal sightings were reported 
during vessel-based activities near Prudhoe Bay in 2008 (Savarese et 
al., 2009). Due to the rarity of these species in the proposed project 
area and the remote chance they would be affected by BP's proposed 
activities at Northstar, these species are not discussed further in 
these proposed regulations.
    BP's application contains information on the status, distribution, 
seasonal distribution, and abundance of each of the six species under 
NMFS jurisdiction likely to be impacted by the proposed activities. 
When reviewing the application, NMFS determined that the species 
descriptions provided by BP correctly characterized the status,

[[Page 39712]]

distribution, seasonal distribution, and abundance of each species. 
Please refer to the application for that information (see ADDRESSES). 
Additional information can also be found in the NMFS Stock Assessment 
Reports (SAR). The 2010 Alaska Marine Mammal SAR is available on the 
Internet at: http://www.nmfs.noaa.gov/pr/pdfs/sars/ak2010.pdf.

Brief Background on Marine Mammal Hearing

    When considering the influence of various kinds of sound on the 
marine environment, it is necessary to understand that different kinds 
of marine life are sensitive to different frequencies of sound. Based 
on available behavioral data, audiograms have been derived using 
auditory evoked potentials, anatomical modeling, and other data, 
Southall et al. (2007) designate ``functional hearing groups'' for 
marine mammals and estimate the lower and upper frequencies of 
functional hearing of the groups. The functional groups and the 
associated frequencies are indicated below (though animals are less 
sensitive to sounds at the outer edge of their functional range and 
most sensitive to sounds of frequencies within a smaller range 
somewhere in the middle of their functional hearing range):
     Low frequency cetaceans (13 species of mysticetes): 
functional hearing is estimated to occur between approximately 7 Hz and 
22 kHz (however, a study by Au et al. (2006) of humpback whale songs 
indicate that the range may extend to at least 24 kHz);
     Mid-frequency cetaceans (32 species of dolphins, six 
species of larger toothed whales, and 19 species of beaked and 
bottlenose whales): functional hearing is estimated to occur between 
approximately 150 Hz and 160 kHz;
     High frequency cetaceans (eight species of true porpoises, 
six species of river dolphins, Kogia, the franciscana, and four species 
of cephalorhynchids): functional hearing is estimated to occur between 
approximately 200 Hz and 180 kHz;
     Pinnipeds in Water: functional hearing is estimated to 
occur between approximately 75 Hz and 75 kHz, with the greatest 
sensitivity between approximately 700 Hz and 20 kHz; and
     Pinnipeds in Air: functional hearing is estimated to occur 
between approximately 75 Hz and 30 kHz.
    As mentioned previously in this document, six marine mammal species 
(three cetacean and three pinniped species) are likely to occur in the 
Northstar facility area. Of the three cetacean species likely to occur 
in BP's project area, two are classified as low frequency cetaceans 
(i.e., bowhead and gray whales) and one is classified as a mid-
frequency cetacean (i.e., beluga whales) (Southall et al., 2007).
    Underwater audiograms have been obtained using behavioral methods 
for four species of phocinid seals: the ringed, harbor, harp, and 
northern elephant seals (reviewed in Richardson et al., 1995b; Kastak 
and Schusterman, 1998). Below 30-50 kHz, the hearing threshold of 
phocinids is essentially flat down to at least 1 kHz and ranges between 
60 and 85 dB re 1 [mu]Pa. There are few published data on in-water 
hearing sensitivity of phocid seals below 1 kHz. However, measurements 
for one harbor seal indicated that, below 1 kHz, its thresholds 
deteriorated gradually to 96 dB re 1 [mu]Pa at 100 Hz from 80 dB re 1 
[mu]Pa at 800 Hz and from 67 dB re 1 [mu]Pa at 1,600 Hz (Kastak and 
Schusterman, 1998). More recent data suggest that harbor seal hearing 
at low frequencies may be more sensitive than that and that earlier 
data were confounded by excessive background noise (Kastelein et al., 
2009a,b). If so, harbor seals have considerably better underwater 
hearing sensitivity at low frequencies than do small odontocetes like 
belugas (for which the threshold at 100 Hz is about 125 dB). In air, 
the upper frequency limit of phocid seals is lower (about 20 kHz).
    Pinniped call characteristics are relevant when assessing potential 
masking effects of man-made sounds. In addition, for those species 
whose hearing has not been tested, call characteristics are useful in 
assessing the frequency range within which hearing is likely to be most 
sensitive. The three species of seals present in the study area, all of 
which are in the phocid seal group, are all most vocal during the 
spring mating season and much less so during late summer. In each 
species, the calls are at frequencies from several hundred to several 
thousand hertz--above the frequency range of the dominant noise 
components from most of the proposed oil production and operational 
activities.
    Cetacean hearing has been studied in relatively few species and 
individuals. The auditory sensitivity of bowhead, gray, and other 
baleen whales has not been measured, but relevant anatomical and 
behavioral evidence is available. These whales appear to be specialized 
for low frequency hearing, with some directional hearing ability 
(reviewed in Richardson et al., 1995b; Ketten, 2000). Their optimum 
hearing overlaps broadly with the low frequency range where BP's 
production activities and associated vessel traffic emit most of their 
energy.
    The beluga whale is one of the better-studied species in terms of 
its hearing ability. As mentioned earlier, the auditory bandwidth in 
mid-frequency odontocetes is believed to range from 150 Hz to 160 kHz 
(Southall et al., 2007); however, belugas are most sensitive above 10 
kHz. They have relatively poor sensitivity at the low frequencies 
(reviewed in Richardson et al., 1995b) that dominate the sound from 
industrial activities and associated vessels. Nonetheless, the noise 
from strong low frequency sources is detectable by belugas many 
kilometers away (Richardson and Wursig, 1997). Also, beluga hearing at 
low frequencies in open-water conditions is apparently somewhat better 
than in the captive situations where most hearing studies were 
conducted (Ridgway and Carder, 1995; Au, 1997). If so, low frequency 
sounds emanating from production activities may be detectable somewhat 
farther away than previously estimated.
    Call characteristics of cetaceans provide some limited information 
on their hearing abilities, although the auditory range often extends 
beyond the range of frequencies contained in the calls. Also, 
understanding the frequencies at which different marine mammal species 
communicate is relevant for the assessment of potential impacts from 
manmade sounds. A summary of the call characteristics for bowhead, 
gray, and beluga whales is provided next. More information is available 
in BP's application (see ADDRESSES).
    Most bowhead calls are tonal, frequency-modulated sounds at 
frequencies of 50-400 Hz. These calls overlap broadly in frequency with 
the underwater sounds emitted by many construction and operational 
activities (Richardson et al., 1995b). Source levels are quite 
variable, with the stronger calls having source levels up to about 180 
dB re 1 [micro]Pa at 1 m. Gray whales make a wide variety of calls at 
frequencies from < 100-2,000 Hz (Moore and Ljungblad, 1984; Dalheim, 
1987).
    Beluga calls include trills, whistles, clicks, bangs, chirps and 
other sounds (Schevill and Lawrence, 1949; Ouellet, 1979; Sjare and 
Smith, 1986a). Beluga whistles have dominant frequencies in the 2-6 kHz 
range (Sjare and Smith, 1986a). This is above the frequency range of 
most of the sound energy produced by the planned Northstar production 
activities and associated vessels. Other beluga call types reported by 
Sjare and Smith (1986a,b) included

[[Page 39713]]

sounds at mean frequencies ranging upward from 1 kHz.
    The beluga also has a very well developed high frequency 
echolocation system, as reviewed by Au (1993). Echolocation signals 
have peak frequencies from 40-120 kHz and broadband source levels of up 
to 219 dB re 1 [mu]Pa-m (zero-peak). Echolocation calls are far above 
the frequency range of the sounds from the planned Northstar 
activities. Therefore, those industrial sounds are not expected to 
interfere with echolocation.

Potential Effects of the Specified Activity on Marine Mammals

    The likely or possible impacts of the planned offshore oil 
developments at Northstar on marine mammals involve both non-acoustic 
and acoustic effects. Potential non-acoustic effects could result from 
the physical presence of personnel, structures and equipment, 
construction or maintenance activities, and the occurrence of oil 
spills. In winter, during ice road construction, and in spring, 
flooding on the sea ice may displace some ringed seals along the ice 
road corridor. There is a small chance that a seal pup might be injured 
or killed by on-ice construction or transportation activities. A major 
oil spill is unlikely and, if it occurred, its effects are difficult to 
predict. Potential impacts from an oil spill are discussed in more 
detail later in this section.
    Petroleum development and associated activities in marine waters 
introduce sound into the environment, produced by island construction, 
maintenance, and drilling, as well as vehicles operating on the ice, 
vessels, aircraft, generators, production machinery, gas flaring, and 
camp operations. The potential effects of sound from the proposed 
activities might include one or more of the following: masking of 
natural sounds; behavioral disturbance and associated habituation 
effects; and, at least in theory, temporary or permanent hearing 
impairment. 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., 1995b):
    (1) The noise may be too weak to be heard at the location of the 
animal (i.e., lower than the prevailing ambient noise level, the 
hearing threshold of the animal at relevant frequencies, or both);
    (2) The noise may be audible but not strong enough to elicit any 
overt behavioral response;
    (3) The noise may elicit reactions of variable conspicuousness and 
variable relevance to the well being of the marine mammal; these can 
range from temporary alert responses to active avoidance reactions such 
as vacating an area at least until the noise event ceases but 
potentially for longer periods of time;
    (4) Upon repeated exposure, a marine mammal may exhibit diminishing 
responsiveness (habituation), or disturbance effects may persist; the 
latter is most likely with sounds that are highly variable in 
characteristics, infrequent, and unpredictable in occurrence, and 
associated with situations that a marine mammal perceives as a threat;
    (5) Any anthropogenic noise that is strong enough to be heard has 
the potential to reduce (mask) the ability of a marine mammal to hear 
natural sounds at similar frequencies, including calls from 
conspecifics, and underwater environmental sounds such as surf noise;
    (6) If mammals remain in an area because it is important for 
feeding, breeding, or some other biologically important purpose even 
though there is chronic exposure to noise, it is possible that there 
could be noise-induced physiological stress; this might in turn have 
negative effects on the well-being or reproduction of the animals 
involved; and
    (7) Very strong sounds have the potential to cause a temporary or 
permanent reduction in hearing sensitivity. In terrestrial mammals, and 
presumably marine mammals, received sound levels must far exceed the 
animal's hearing threshold for there to be any temporary threshold 
shift (TTS) in its hearing ability. For transient sounds, the sound 
level necessary to cause TTS is inversely related to the duration of 
the sound. Received sound levels must be even higher for there to be 
risk of permanent hearing impairment. In addition, intense acoustic or 
explosive events may cause trauma to tissues associated with organs 
vital for hearing, sound production, respiration and other functions. 
This trauma may include minor to severe hemorrhage.
    The characteristics of the various sound sources at Northstar were 
summarized earlier in this document (see the ``Description of the 
Specified Activity'' section). Additionally, BP's application contains 
more details on the Northstar sound characteristics, underwater and in-
air sound propagation in and around Northstar, and ambient noise levels 
in the waters near Prudhoe Bay, Alaska. Please refer to that document 
for more information (see ADDRESSES).

Potential Effects of Sound on Cetaceans

(1) Masking
    Masking is the obscuring of sounds of interest by other sounds, 
often at similar frequencies. Marine mammals are highly dependent on 
sound, and their ability to recognize sound signals amid other noise is 
important in communication, predator and prey detection, and, in the 
case of toothed whales, echolocation. Even in the absence of manmade 
sounds, the sea is usually noisy. Background ambient noise often 
interferes with or masks the ability of an animal to detect a sound 
signal even when that signal is above its absolute hearing threshold. 
Natural ambient noise includes contributions from wind, waves, 
precipitation, other animals, and (at frequencies above 30 kHz) thermal 
noise resulting from molecular agitation (Richardson et al., 1995b). 
Background noise also can include sounds from human activities. Masking 
of natural sounds can result when human activities produce high levels 
of background noise. Conversely, if the background level of underwater 
noise is high (e.g., on a day with strong wind and high waves), an 
anthropogenic noise source will not be detectable as far away as would 
be possible under quieter conditions and will itself be masked.
    Although some degree of masking is inevitable when high levels of 
manmade broadband sounds are introduced into the sea, marine mammals 
have evolved systems and behavior that function to reduce the impacts 
of masking. Structured signals, such as the echolocation click 
sequences of small toothed whales, may be readily detected even in the 
presence of strong background noise because their frequency content and 
temporal features usually differ strongly from those of the background 
noise (Au and Moore, 1988, 1990). The components of background noise 
that are similar in frequency to the sound signal in question primarily 
determine the degree of masking of that signal.
    Redundancy and context can also facilitate detection of weak 
signals. These phenomena may help marine mammals detect weak sounds in 
the presence of natural or manmade noise. Most masking studies in 
marine mammals present the test signal and the masking noise from the 
same direction. The sound localization abilities of marine mammals 
suggest that, if signal and noise come from different directions, 
masking would not be as severe as the usual types of masking studies 
might suggest (Richardson et al., 1995b). The dominant background noise

[[Page 39714]]

may be highly directional if it comes from a particular anthropogenic 
source such as a ship or industrial site. Directional hearing may 
significantly reduce the masking effects of these noises by improving 
the effective signal-to-noise ratio. In the cases of high-frequency 
hearing by the bottlenose dolphin, beluga whale, and killer whale, 
empirical evidence confirms that masking depends strongly on the 
relative directions of arrival of sound signals and the masking noise 
(Penner et al., 1986; Dubrovskiy, 1990; Bain et al., 1993; Bain and 
Dahlheim, 1994). Toothed whales, and probably other marine mammals as 
well, have additional capabilities besides directional hearing that can 
facilitate detection of sounds in the presence of background noise. 
There is evidence that some toothed whales can shift the dominant 
frequencies of their echolocation signals from a frequency range with a 
lot of ambient noise toward frequencies with less noise (Au et al., 
1974, 1985; Moore and Pawloski, 1990; Thomas and Turl, 1990; Romanenko 
and Kitain, 1992; Lesage et al., 1999). A few marine mammal species are 
known to increase the source levels or alter the frequency of their 
calls in the presence of elevated sound levels (Dahlheim, 1987; Au, 
1993; Lesage et al., 1993, 1999; Terhune, 1999; Foote et al., 2004; 
Parks et al., 2007, 2009; Di Iorio and Clark, 2009; Holt et al., 2009).
    These data demonstrating adaptations for reduced masking pertain 
mainly to the very high frequency echolocation signals of toothed 
whales. There is less information about the existence of corresponding 
mechanisms at moderate or low frequencies or in other types of marine 
mammals. For example, Zaitseva et al. (1980) found that, for the 
bottlenose dolphin, the angular separation between a sound source and a 
masking noise source had little effect on the degree of masking when 
the sound frequency was 18 kHz, in contrast to the pronounced effect at 
higher frequencies. Directional hearing has been demonstrated at 
frequencies as low as 0.5-2 kHz in several marine mammals, including 
killer whales (Richardson et al., 1995b). This ability may be useful in 
reducing masking at these frequencies. In summary, high levels of noise 
generated by anthropogenic activities may act to mask the detection of 
weaker biologically important sounds by some marine mammals. This 
masking may be more prominent for lower frequencies. For higher 
frequencies, such as that used in echolocation by toothed whales, 
several mechanisms are available that may allow them to reduce the 
effects of such masking.
    There would be no masking effects on cetaceans from BP's proposed 
activities during the ice-covered season because cetaceans will not 
occur near Northstar at that time. The sounds from oil production and 
any drilling activities are not expected to be detectable beyond 
several kilometers from the source (Greene, 1983; Blackwell et al., 
2004b; Blackwell and Greene, 2005, 2006). Sounds from vessel activity, 
however, were detectable to distances as far as approximately 18.6 mi 
(30 km) from Northstar (Blackwell and Greene, 2006). Vessels under 
power to maintain position can be a source of continuous noise in the 
marine environment (Blackwell et al., 2004b; Blackwell and Greene, 
2006) and therefore have the potential to cause some degree of masking.
    Small numbers of bowheads, belugas and (rarely) gray whales could 
be present near Northstar during the open-water season. Almost all 
energy in the sounds emitted by drilling and other operational 
activities is at low frequencies, predominantly below 250 Hz with 
another peak centered around 1,000 Hz. Most energy in the sounds from 
the vessels and aircraft to be used during this project is below 1 kHz 
(Moore et al., 1984; Greene and Moore, 1995; Blackwell et al., 2004b; 
Blackwell and Greene, 2006). These frequencies are mainly used by 
mysticetes but not by odontocetes. Therefore, masking effects would 
potentially be more pronounced in the bowhead and gray whales that 
might occur in the proposed project area.
    Because of the relatively low effective source levels and rapid 
attenuation of drilling and production sounds from artificial islands 
in shallow water, masking effects are unlikely even for mysticetes that 
are within several kilometers of Northstar Island. Vessels that are 
docking or under power to maintain position could cause some degree of 
masking. However, the adaptation of some cetaceans to alter the source 
level or frequency of their calls, along with directional hearing, pre-
adaptation to tolerate some masking by natural sounds, and the brief 
periods when most individual whales occur near Northstar, would all 
reduce the potential impacts of masking from BP's proposed activities. 
Therefore, impacts from masking on cetaceans are anticipated to be 
minor.
(2) Behavioral Disturbance
    Disturbance can induce a variety of effects, such as subtle changes 
in behavior, more conspicuous dramatic changes in activities, and 
displacement. A main concern about the impacts of manmade noise on 
marine mammals is the potential for disturbance. Behavioral reactions 
of marine mammals to sound are difficult to predict because they are 
dependent on numerous factors, including species, state of maturity, 
experience, current activity, reproductive state, time of day, and 
weather.
    When the received level of noise exceeds some behavioral reaction 
threshold, it is possible that some cetaceans could exhibit disturbance 
reactions. The levels, frequencies and types of noise that elicit a 
response vary among and within species, individuals, locations, and 
seasons. Behavioral changes may be subtle alterations in surface-
respiration-dive cycles, changes in activity or aerial displays, 
movement away from the sound source, or complete avoidance of the area. 
The reaction threshold and degree of response are related to the 
activity of the animal at the time of the disturbance. Whales engaged 
in active behaviors such as feeding, socializing, or mating are less 
likely than resting animals to show overt behavioral reactions. 
However, they may do so if the received noise level is high or the 
source of disturbance is directly threatening.
    Some researchers have noted that behavioral reactions do not occur 
throughout the entire zone ensonified by industrial activity. In most 
cases that have been studied, including work on bowhead, gray, and 
beluga whales, the actual radius of effect is smaller than the radius 
of detectability (reviewed in Richardson and Malme, 1993; Richardson et 
al., 1995b; Nowacek et al., 2007; Southall et al., 2007).
    Effects of Construction, Drilling, and Production Activity--Spring 
migration of bowheads and belugas through the western and central 
Beaufort Sea occurs from April to June. Their spring migration 
corridors are far north of the barrier islands and of the Northstar 
project area. Whales, including bowhead, beluga, and gray, will not be 
within the Northstar project area during winter or spring. In addition, 
industrial sounds from Northstar are unlikely to be detectable far 
enough offshore to be heard by spring-migrating whales. In rare cases 
where these sounds might be audible to cetaceans in spring, the 
received levels would be weak and unlikely to elicit behavioral 
reactions. Consequently, noise from construction and operational 
activities at Northstar during the ice-covered season would have 
minimal, if any, effect on whales.
    During the open-water season, sound propagation from sources on the 
island

[[Page 39715]]

is reduced because of poor coupling of sound through the gravel island 
into the shallow waters. In the absence of boats, underwater sounds 
from Northstar Island during construction, drilling, and production 
reached background values 1.2-2.5 mi (2-4 km) away in quiet conditions 
(Blackwell and Greene, 2006). However, when Northstar-related vessels 
were present, levels were higher and faint vessel sound was often still 
evident 12.4-18.6 mi (20-30 km) away.
    Information about the reactions of cetaceans to construction or 
heavy equipment activity on artificial (or natural) islands is limited 
(Richardson et al., 1995b). During the construction of artificial 
islands and other oil-industry facilities in the Canadian Beaufort Sea 
during late summers of 1980-1984, bowheads were at times observed as 
close as 0.5 mi (0.8 km) from the construction sites (Richardson et 
al., 1985, 1990). Richardson et al. (1990) showed that, at least in 
summer, bowheads generally tolerated playbacks of low-frequency 
construction and dredging noise at received broadband levels up to 
about 115 dB re 1 [mu]Pa. At received levels higher than about 115 dB, 
some avoidance reactions were observed. Bowheads apparently reacted in 
only a limited and localized way (if at all) to construction of Seal 
Island, the precursor of Northstar (Hickie and Davis, 1983).
    There are no specific data on reactions of bowhead or gray whales 
to noise from drilling on an artificial island. However, playback 
studies have shown that both species begin to display overt behavioral 
responses to various low-frequency industrial sounds when received 
levels exceed 110-120 dB re 1 [mu]Pa (Malme et al., 1984; Richardson et 
al., 1990, 1995a, 1995b). The overall received level of drilling sound 
from Northstar Island generally diminished to 115 dB within 0.62 mi (1 
km; Blackwell et al., 2004b). Therefore, any reactions by bowhead or 
gray whales to drilling at Northstar were expected to be highly 
localized, involving few whales.
    Prior to construction of Northstar, it was expected (based on early 
data mentioned earlier) that some bowheads would avoid areas where 
noise levels exceeded 115 dB re 1 [mu]Pa (Richardson et al., 1990). On 
their summer range in the Beaufort Sea, bowhead whales were observed 
reacting to drillship noises within 2.5-5 mi (4-8 km) of the drillship 
at received levels 20 dB above ambient (Richardson et al., 1990). It 
was expected that, during most autumn migration seasons, few bowheads 
would come close enough to shore to receive sound levels that high from 
Northstar. Thus disturbance effects from continuous construction and 
operational noise were expected to be limited to the closest whales and 
the times with highest sound emissions.
    In 2000-2004, bowhead whales were monitored acoustically to 
determine the number of whales that might have been exposed to 
Northstar-related sounds. Data from 2001-2004 were useable for this 
purpose. The results showed that, during late summer and early autumn 
of 2001, a small number of bowhead whales in the southern part of the 
migration corridor (closest to Northstar) were apparently affected by 
vessel or Northstar operations. At these times, most ``Northstar 
sound'' was from maneuvering vessels, not the island itself. The 
distribution of calling whales was analyzed, and the results indicated 
that the apparent southern (proximal) edge of the call distribution was 
significantly associated with the level of industrial sound output each 
year, with the southern edge of the call distribution varying by 0.47 
mi to 1.46 mi (0.76 km to 2.35 km; depending on year) farther offshore 
when underwater sound levels from Northstar and associated vessels were 
above average (Richardson et al., 2008a). It is possible that the 
apparent deflection effect was, at least in part, attributable to a 
change in calling behavior rather than actual deflection. In either 
case, there was a change in the behavior of some bowhead whales.
    Nowacek et al. (2004) used controlled exposures to demonstrate 
behavioral reactions of North Atlantic right whales (a species closely 
related to the bowhead whale) to various non-pulse sounds. Playback 
stimuli included ship noise, social sounds of conspecifics, and a 
complex, 18-min ``alert'' sound consisting of repetitions of three 
different artificial signals. Ten whales were tagged with calibrated 
instruments that measured received sound characteristics and concurrent 
animal movements in three dimensions. Five out of six exposed whales 
reacted strongly to alert signals at measured received levels between 
130 and 150 dB (i.e., ceased foraging and swam rapidly to the surface). 
Two of these individuals were not exposed to ship noise, and the other 
four were exposed to both stimuli. These whales reacted mildly to 
conspecific signals. Seven whales, including the four exposed to the 
alert stimulus, had no measurable response to either ship sounds or 
actual vessel noise.
    There are no data on the reactions of gray whales to production 
activities similar to those in operation at Northstar. Oil production 
platforms of a very different type have been in place off California 
for many years. Gray whales regularly migrate through that area 
(Brownell, 1971), but no detailed data on distances of closest approach 
or possible noise disturbance have been published. Oil industry 
personnel have reported seeing whales near platforms, and that the 
animals approach more closely during low-noise periods (Gales, 1982; 
McCarty, 1982). Playbacks of recorded production platform noise 
indicate that gray whales react if received levels exceed approximately 
123 dB re 1 [mu]Pa--similar to the levels of drilling noise that elicit 
avoidance (Malme et al., 1984).
    A typical migrating gray whale tolerates steady, low-frequency 
industrial sounds at received levels up to about 120 dB re 1 [mu]Pa 
(Malme et al., 1984). Gray whales may tolerate higher-level sounds if 
the sound source is offset to the side of the migration path (Tyack and 
Clark, 1998). Also, gray whales generally tolerate repeated low-
frequency seismic pulses at received levels up to about 163-170 dB re 1 
[mu]Pa measured on an (approximate) rms basis. Above those levels, 
avoidance is common. Because the reaction thresholds to both steady and 
pulsed sounds are slightly higher than corresponding values for 
bowheads, reaction distances for gray whales would be slightly less 
than those for bowheads.
    In the Canadian Beaufort Sea, beluga whales were seen within 
several feet of an artificial island. During the island's construction, 
belugas were displaced from the immediate vicinity of the island but 
not from the general area (Fraker, 1977a). Belugas in the Mackenzie 
River estuary showed less response to a stationary dredge than to 
moving tug/barge traffic. They approached as close as 1,312 ft (400 m) 
from stationary dredges. Underwater sounds from Northstar Island are 
weaker than those from the dredge. In addition, belugas occur only 
infrequently in nearshore waters in the Prudhoe Bay region. They also 
have relatively poor hearing sensitivity at the low frequencies of most 
construction noises. Therefore, effects of construction and related 
sounds on belugas would be expected to be minimal.
    Responses of beluga whales to drilling operations are described in 
Richardson et al. (1995a) and summarized here. In the Mackenzie Estuary 
during summer, belugas have been seen regularly within 328 to 492 ft 
(100 to 150 m) of artificial islands (Fraker 1977a,b; Fraker and 
Fraker, 1979). However, in the Northstar area, belugas are present only 
during late summer and autumn, and almost all of them are migrating 
through offshore

[[Page 39716]]

waters far seaward of Northstar. Only a very small proportion of the 
population enters nearshore waters. In spring, migrating belugas showed 
no overt reactions to recorded drilling noise (<350 Hz) until within 
656 to 1,312 ft (200 to 400 m) of the source, even though the sounds 
were measurable up to 3.1 mi away (5 km; Richardson et al., 1991). 
During another drilling noise playback study, overt reactions by 
belugas within 164 to 984 ft (50 to 300 m) involved increased swimming 
speed or reversal of direction of travel (Stewart et al., 1983). The 
short reaction distances are probably partly a consequence of the poor 
hearing sensitivity of belugas at low frequencies (Richardson et al., 
1995b). In general, very few belugas are expected to approach Northstar 
Island, and any such occurrences would be restricted to the late 
summer/autumn period.
    There are no specific data on the reactions of beluga whales to 
production operations similar to those at Northstar. Personnel from 
production platforms in Cook Inlet, Alaska, report that belugas are 
seen within 30 ft (9 m) of some rigs, and that steady noise is non-
disturbing to belugas (Gales, 1982; McCarty, 1982). Beluga whales are 
regularly observed near the Port of Anchorage and the extensive 
dredging/maintenance activities that operate there (NMFS, 2003). Pilot 
whales, killer whales, and unidentified dolphins were also reported 
near Cook Inlet platforms. In that area, flare booms might attract 
belugas, possibly because the flares attract salmon in that area. 
Attraction of belugas to prey concentrations is not likely to occur at 
Northstar because belugas are predominantly migrating rather than 
feeding when in that area and because only a very small proportion of 
the beluga population occurs in nearshore waters. Overall, effects of 
routine production activities on belugas are expected to be minimal.
    Effects of Aircraft Activity--Helicopters are the only aircraft 
associated with Northstar drilling and oil production operations for 
crew transfer and supply and support. Helicopter traffic occurs during 
late spring/summer and fall/early winter when travel by ice roads, 
hovercraft, or vessels is not possible. Twin Otters are used for 
routine pipeline inspections.
    Potential effects to cetaceans from aircraft activity could involve 
both acoustic and non-acoustic effects. It is uncertain if the animals 
react to the sound of the aircraft or to its physical presence flying 
overhead. Low passes by aircraft over a cetacean, including a bowhead, 
gray, or beluga whale, can result in short-term responses or no 
discernible reaction. Responses can include sudden dives, breaching, 
churning the water with the flippers and/or flukes, or rapidly swimming 
away from the aircraft track (reviewed in Richardson et al., 1995b; 
updated review in Luksenburg and Parsons, 2009). These studies have 
found that various factors affect cetacean responses to aircraft noise. 
Some of these factors include species, behavioral state at the time of 
the exposure, and altitude and lateral distance of the aircraft to the 
animal. For example, Wursig et al. (1998) found that resting 
individuals appeared to be more sensitive to the disturbance.
    Patenaude et al. (2002) recorded reactions of bowhead and beluga 
whales to a Bell 212 helicopter and Twin Otter fixed-wing aircraft 
during four spring seasons (1989-1991 and 1994) in the western Beaufort 
Sea. Responses were more common to the helicopter than to the fixed-
wing aircraft. The authors noted responses by 38% of belugas (n = 40) 
and 14% of bowheads (n = 63) to the helicopter, whereas only 3.2% of 
belugas (n = 760) and 2.2% of bowheads (n = 507) reacted to the Twin 
Otter. Common responses to the helicopter included immediate dives, 
changes in heading, changes in behavioral state, and apparent 
displacement for belugas and abrupt dives and breaching for bowheads 
(Patenaude et al., 2002). Similar reactions were observed by the 
authors from the fixed-wing aircraft: Immediate dives with a tail 
thrash, turns or changes in heading, and twists to look upwards for 
belugas and unusually short surfacing for bowheads. For both species, 
the authors noted that responses were seen more often when the 
helicopter was below 492 ft (150 m) altitude and at a lateral distance 
of less than 820 ft (250 m) and when the Twin Otter was below 597 ft 
(182 m) altitude and at a lateral distance of less than 820 ft (250 m).
    During their study, Patenaude et al. (2002) observed one bowhead 
whale cow-calf pair during four passes totaling 2.8 hours of the 
helicopter and two pairs during Twin Otter overflights. All of the 
helicopter passes were at altitudes of 49-98 ft (15-30 m). The mother 
dove both times she was at the surface, and the calf dove once out of 
the four times it was at the surface. For the cow-calf pair sightings 
during Twin Otter overflights, the authors did not note any behaviors 
specific to those pairs. Rather, the reactions of the cow-calf pairs 
were lumped with the reactions of other groups that did not consist of 
calves.
    Richardson et al. (1995b) and Moore and Clarke (2002) reviewed a 
few studies that observed responses of gray whales to aircraft. Cow-
calf pairs were quite sensitive to a turboprop survey flown at 1,000 ft 
(305 m) altitude on the Alaskan summering grounds. In that survey, 
adults were seen swimming over the calf, or the calf swam under the 
adult (Ljungblad et al., 1983, cited in Richardson et al., 1995b and 
Moore and Clarke, 2002). However, when the same aircraft circled for 
more than 10 minutes at 1,050 ft (320 m) altitude over a group of 
mating gray whales, no reactions were observed (Ljungblad et al., 1987, 
cited in Moore and Clarke, 2002). Malme et al. (1984, cited in 
Richardson et al., 1995b and Moore and Clarke, 2002) conducted playback 
experiments on migrating gray whales. They exposed the animals to 
underwater noise recorded from a Bell 212 helicopter (estimated 
altitude = 328 ft [100 m]), at an average of three simulated passes per 
minute. The authors observed that whales changed their swimming course 
and sometimes slowed down in response to the playback sound but 
proceeded to migrate past the transducer. Migrating gray whales did not 
react overtly to a Bell 212 helicopter at greater than 1,394 ft (425 m) 
altitude, occasionally reacted when the helicopter was at 1,000-1,198 
ft (305-365 m), and usually reacted when it was below 825 ft (250 m; 
Southwest Research Associates, 1988, cited in Richardson et al., 1995b 
and Moore and Clarke, 2002). Reactions noted in that study included 
abrupt turns or dives or both. Green et al. (1992, cited in Richardson 
et al., 1995b) observed that migrating gray whales rarely exhibited 
noticeable reactions to a straight-line overflight by a Twin Otter at 
197 ft (60 m) altitude.
    There is little likelihood of project-related helicopter and 
aircraft traffic over bowheads during their westward fall migration 
through the Beaufort Sea. Helicopter and aircraft traffic is between 
the shore and Northstar Island. Most bowhead whales migrate west in 
waters farther north than the island. Helicopters maintain an altitude 
of 1,000 ft (305 m) above sea level while traveling over water to and 
from Northstar whenever weather conditions allow. It is unlikely that 
there will be any need for helicopters or aircraft to circle or hover 
over the open water other than when landing or taking off. Gray whales 
are uncommon in the area, and there is little likelihood that any will 
be overflown by a helicopter or aircraft. The planned flight altitude 
will minimize any disturbance that might occur if a gray whale is 
encountered. Likewise, there is little likelihood of helicopter 
disturbance to belugas.

[[Page 39717]]

Because of the predominantly offshore migration route of belugas, very 
few (if any) will be overflown during flights over nearshore waters. 
Any overflights are most likely to be at an altitude of 1,000 ft (305 
m) or more, weather permitting. This is greater than the altitude at 
which belugas and bowheads typically react to aircraft (Patenaude et 
al., 2002). Therefore, few belugas or bowheads are expected to react to 
aircraft overflights near the Northstar facility. Additionally, 
reactions are expected to be brief.
    Effects of Vessel Activity--Reactions of cetaceans to vessels often 
include changes in general activity (e.g., from resting or feeding to 
active avoidance), changes in surfacing-respiration-dive cycles, and 
changes in speed and direction of movement. As with aircraft, responses 
to vessel approaches tend to be reduced if the animals are actively 
involved in a specific activity such as feeding or socializing 
(reviewed in Richardson et al., 1995b). Past experiences of the animals 
with vessels are important in determining the degree and type of 
response elicited from a whale-vessel encounter.
    Whales react most noticeably to erratically moving vessels with 
varying engine speeds and gear changes and to vessels in active 
pursuit. Avoidance reactions by bowheads sometimes begin as subtle 
alterations in whale activity, speed and heading as far as 2.5 mi (4 
km) from the vessel. Consequently, the closest point of approach is 
farther from the vessel than if the cetacean had not altered course. 
Bowheads sometimes begin to swim actively away from approaching vessels 
when they come within 1.2-2.5 mi (2-4 km). If the vessel approaches to 
within several hundred meters, the response becomes more noticeable, 
and whales sometimes change direction to swim perpendicularly away from 
the vessel path (Richardson et al., 1985, 1995b; Richardson and Malme, 
1993).
    North Atlantic right whales (a species closely related to the 
bowhead whale) also display variable responses to boats. There may be 
an initial orientation away from a boat, followed by a lack of 
observable reaction (Atkins and Swartz, 1989). A slowly moving boat can 
approach a right whale, but an abrupt change in course or engine speed 
usually elicits a reaction (Goodyear, 1989; Mayo and Marx, 1990; 
Gaskin, 1991). When approached by a boat, right whale mothers will 
interpose themselves between the vessel and calf and will maintain a 
low profile (Richardson et al., 1995b). In a long-term study of baleen 
whale reactions to boats, while other baleen whale species appeared to 
habituate to boat presence over the 25-year period, right whales 
continued to show either uninterested or negative reactions to boats 
with no change over time (Watkins, 1986).
    Beluga whales are generally quite responsive to vessels. Belugas in 
Lancaster Sound in the Canadian Arctic showed dramatic reactions in 
response to icebreaking ships, with received levels of sound ranging 
from 101 dB to 136 dB re 1 [mu]Pa in the 20 to 1,000-Hz band at a depth 
of 66 ft (20 m; Finley et al., 1990). Responses included emitting 
distinctive pulsive calls that were suggestive of excitement or alarm 
and rapid movement in what seemed to be a flight response. Reactions 
occurred out to 50 mi (80 km) from the ship. Another study found 
belugas use higher-frequency calls, a greater redundancy in their calls 
(more calls emitted in a series), and a lower calling rate in the 
presence of vessels (Lesage et al., 1999). The level of response of 
belugas to vessels is thought to be partly a function of habituation.
    During the drilling and oil production phase of the Northstar 
development, most vessel traffic involves slow-moving tugs and barges 
and smaller faster-moving vessels providing local transport of 
equipment, supplies, and personnel. Much of this traffic will occur 
during August and early September before many whales are in the area. 
Some vessel traffic during the broken ice periods in the spring and 
fall may also occur. Alternatively, small hovercraft may be used during 
the spring and fall when the ice is too thin to allow safe passage by 
large vehicles over the ice road.
    Whale reactions to slow-moving vessels are less dramatic than their 
reactions to faster and/or erratic vessel movements. Bowhead, gray, and 
beluga whales often tolerate the approach of slow-moving vessels within 
several hundred meters. This is especially so when the vessel is not 
directed toward the whale and when there are no sudden changes in 
direction or engine speed (Wartzok et al., 1989; Richardson et al., 
1995b; Heide-Jorgensen et al., 2003).
    Most vessel traffic associated with Northstar will be inshore of 
the bowhead and beluga migration corridor and/or prior to the migration 
season of bowhead and beluga whales. Underwater sounds from hovercraft 
are generally lower than for standard vessels since the sound is 
generated in air, rather than underwater. If vessels or hovercraft do 
approach whales, a small number of individuals may show short-term 
avoidance reactions.
    The highest levels of underwater sound produced by routine 
Northstar operations are generally associated with Northstar-related 
vessel operations. These vessel operations around Northstar sometimes 
result in sound levels high enough that a small number of the bowheads 
in the southern part of the migration corridor appear to be deflected 
slightly offshore. To the extent that offshore deflection occurs as a 
result of Northstar, it is mainly attributable to Northstar-related 
vessel operations. As previously described, this deflection is expected 
to involve few whales and generally small deflections.
(3) Hearing Impairment and Other Physiological Effects
    Temporary or permanent hearing impairment is a possibility when 
marine mammals are exposed to very strong sounds. Non-auditory 
physiological effects might also occur in marine mammals exposed to 
strong underwater sound. Possible types of non-auditory physiological 
effects or injuries that theoretically might occur in mammals close to 
a strong sound source include stress, neurological effects, bubble 
formation, and other types of organ or tissue damage. It is possible 
that some marine mammal species (i.e., beaked whales) may be especially 
susceptible to injury and/or stranding when exposed to strong sounds, 
particularly at higher frequencies. There are no beaked whale species 
found in the proposed project area. Cetaceans are not anticipated to 
experience non-auditory physiological effects as a result of operation 
of the Northstar facility, as none of the activities associated with 
the facility will generate sounds loud enough to cause such effects.
    Temporary Threshold Shift (TTS)--TTS is the mildest form of hearing 
impairment that can occur during exposure to a strong sound (Kryter, 
1985). While experiencing TTS, the hearing threshold rises, and a sound 
must be stronger in order to be heard. At least in terrestrial mammals, 
TTS can last from minutes or hours to (in cases of strong TTS) days. 
For sound exposures at or somewhat above the TTS threshold, hearing 
sensitivity in both terrestrial and marine mammals recovers rapidly 
after exposure to the noise ends. Few data on sound levels and 
durations necessary to elicit mild TTS have been obtained for marine 
mammals, and none of the published data concern TTS elicited by 
exposure to multiple pulses of sound.
    Human non-impulsive noise exposure guidelines are based on 
exposures of equal energy (the same sound exposure

[[Page 39718]]

level [SEL]) producing equal amounts of hearing impairment regardless 
of how the sound energy is distributed in time (NIOSH, 1998). Until 
recently, previous marine mammal TTS studies have also generally 
supported this equal energy relationship (Southall et al., 2007). Three 
newer studies, two by Mooney et al. (2009a, b) on a single bottlenose 
dolphin either exposed to playbacks of U.S. Navy mid-frequency active 
sonar or octave-band noise (4-8 kHz) and one by Kastak et al. (2007) on 
a single California sea lion exposed to airborne octave-band noise 
(centered at 2.5 kHz), concluded that for all noise exposure 
situations, the equal energy relationship may not be the best indicator 
to predict TTS onset levels. Generally, with sound exposures of equal 
energy, those that were quieter (lower sound pressure level [SPL]) with 
longer duration were found to induce TTS onset more than those of 
louder (higher SPL) and shorter duration. Given the available data, the 
received level of a single seismic pulse (with no frequency weighting) 
might need to be approximately 186 dB re 1 [mu]Pa [middot] 2. s (i.e., 
186 dB SEL) in order to produce brief, mild TTS. NMFS considers TTS to 
be a form of Level B harassment, which temporarily causes a shift in an 
animal's hearing, and the animal is able to recover. Data on TTS from 
continuous sound (such as that produced by many of BP's Northstar 
activities) are limited, so available data from seismic activities are 
used as a proxy. Exposure to several strong seismic pulses that each 
have received levels near 175-180 dB SEL might result in slight TTS in 
a small odontocete, assuming the TTS threshold is (to a first 
approximation) a function of the total received pulse energy. Given 
that the SPL is approximately 10-15 dB higher than the SEL value for 
the same pulse, an odontocete would need to be exposed to a sound level 
of 190 dB re 1 [mu]Pa (rms) in order to incur TTS.
    TTS was measured in a single, captive bottlenose dolphin after 
exposure to a continuous tone with maximum SPLs at frequencies ranging 
from 4 to 11 kHz that were gradually increased in intensity to 179 dB 
re 1 [mu]Pa and in duration to 55 minutes (Nachtigall et al., 2003). No 
threshold shifts were measured at SPLs of 165 or 171 dB re 1 [mu]Pa. 
However, at 179 dB re 1 [mu]Pa, TTSs greater than 10 dB were measured 
during different trials with exposures ranging from 47 to 54 minutes. 
Hearing sensitivity apparently recovered within 45 minutes after noise 
exposure.
    Schlundt et al. (2000) measure masked TTS (i.e., band-limited white 
noise, masking noise, was introduced into the testing environment to 
keep thresholds consistent despite variations in ambient noise levels) 
in five bottlenose dolphins and two beluga whales during eight 
experiments conducted over 2.3 years. The test subjects were exposed to 
1-s pure tones at frequencies of 0.4, 3, 10, 20, and 75 kHz. Over the 
course of the eight experiments, Schlundt et al. (2000) conducted a 
total of 195 masked TTS sessions, and 11 of those sessions produced 
masked TTSs. The authors found that the levels needed to induce a 6 dB 
or larger masked TTS were generally between 192 and 201 dB re 1 [mu]Pa. 
No subjects exhibited shifts at levels up to 193 dB re 1 [mu]Pa for 
tones played at 0.4 kHz (Schlundt et al., 2000). The authors found that 
at the conclusion of each experiment, all thresholds were within 3 dB 
of baseline values. Additionally, they did not note any permanent 
shifts in hearing thresholds (Schlundt et al., 2000).
    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 background noise levels at 
those low frequencies tend to be higher. Marine mammals can hear sounds 
at varying frequency levels. However, sounds that are produced in the 
frequency range at which an animal hears the best do not need to be as 
loud as sounds in less functional frequencies to be detected by the 
animal. 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). Therefore, for a sound to be audible, baleen 
whales require sounds to be louder (i.e., higher dB levels) than 
odontocetes in the frequency ranges at which each group hears the best. 
Based on this information, it is suspected that received levels causing 
TTS onset may also be higher in baleen whales. Since current NMFS 
practice assumes the same thresholds for the onset of hearing 
impairment in both odontocetes and mysticetes, NMFS' onset of TTS 
threshold is likely conservative for mysticetes.
    NMFS (1995, 2000) concluded that cetaceans should not be exposed to 
pulsed underwater noise at received levels exceeding 180 dB re 1 [mu]Pa 
(rms). The established 180-dB re 1 [mu]Pa (rms) criterion is not 
considered to be the level above which TTS might occur in cetaceans. 
Rather, it is the received level 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 
cetaceans. Levels of underwater sound from production and drilling 
activities that occur continuously over extended periods at Northstar 
are not very high (Blackwell and Greene, 2006). For example, received 
levels of prolonged drilling sounds are expected to diminish below 140 
dB re 1 [mu]Pa at a distance of about 131 ft (40 m) from the center of 
activity. Sound levels during production activities other than drilling 
usually would diminish below 140 dB re 1 [mu]Pa at a closer distance. 
The 140 dB re 1 [mu]Pa radius for drilling noise is within the island 
and drilling sounds are attenuated to levels below 140 dB re 1 [mu]Pa 
in the water near Northstar. Additionally, cetaceans are not commonly 
found in the area during the ice-covered season. Based on this 
information and the available data, TTS of cetaceans is not expected 
from the operations at Northstar.
    Permanent Threshold Shift (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.
    There is no specific evidence that exposure to underwater 
industrial sounds can cause PTS in any marine mammal (see Southall et 
al., 2007). However, given the possibility that marine mammals might 
incur TTS, there has been further speculation about the possibility 
that some individuals occurring very close to industrial activities 
might incur PTS. Richardson et al. (1995b) hypothesized that PTS caused 
by prolonged exposure to continuous anthropogenic sound is unlikely to 
occur in marine mammals, at least for sounds with source levels up to 
approximately 200 dB re 1 [mu]Pa at 1 m (rms). Single or occasional 
occurrences of mild TTS are not indicative of permanent auditory damage 
in terrestrial mammals. Relationships between TTS and PTS thresholds 
have not been studied in marine mammals but are assumed to be similar 
to those in humans and other terrestrial mammals. PTS might occur at a 
received sound level at least several decibels above that inducing mild 
TTS.
    It is highly unlikely that cetaceans could receive sounds strong 
enough (and over a sufficient duration) to cause PTS (or even TTS) 
during the proposed operation of the Northstar facility. Source levels 
for much of the equipment

[[Page 39719]]

used at Northstar do not reach the threshold of 180 dB (rms) currently 
used for cetaceans. Based on this conclusion, it is highly unlikely 
that any type of hearing impairment, temporary or permanent, would 
occur as a result of BP's proposed activities. Additionally, Southall 
et al. (2007) proposed that the thresholds for injury of marine mammals 
exposed to ``discrete'' noise events (either single or multiple 
exposures over a 24-hr period) are higher than the 180-dB re 1 [mu]Pa 
(rms) in-water threshold currently used by NMFS. Table 1 in this 
document summarizes the SPL and SEL levels thought to cause auditory 
injury to cetaceans. For more information, please refer to Southall et 
al. (2007).

 Table 1--Proposed Injury Criteria for Low- and Mid-Frequency Cetaceans Exposed to ``Discrete'' Noise Events (Either Single Pulses, Multiple Pulses, or
                                                Non-Pulses Within a 24-Hr Period; Southall et al., 2007)
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                            Single pulses                           Multiple pulses                             Non pulses
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                 Low-frequency cetaceans
--------------------------------------------------------------------------------------------------------------------------------------------------------
Sound pressure level.........  230 dB re 1 [mu]Pa (peak) (flat)         230 dB re 1 [mu]Pa (peak) (flat)         230 dB re 1 [mu]Pa (peak) (flat)
Sound exposure level.........  198 dB re 1 [mu]Pa\2\-s (Mlf)            198 dB re 1 [mu]Pa\2\-s (Mlf)            215 dB re 1 [mu]Pa\2\-s (Mlf)
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                 Mid-frequency cetaceans
--------------------------------------------------------------------------------------------------------------------------------------------------------
Sound pressure level.........  230 dB re 1 [mu]Pa (peak) (flat)         230 dB re 1 [mu]Pa (peak) (flat)         230 dB re 1 [mu]Pa (peak) (flat)
Sound exposure level.........  198 dB re 1 [mu]Pa\2\-s (Mlf)            198 dB re 1 [mu]Pa\2\-s (Mlf)            215 dB re 1 [mu]Pa\2\-s (Mlf)
--------------------------------------------------------------------------------------------------------------------------------------------------------

Potential Effects of Sound on Pinnipeds

(1) Masking
    As stated previously in this document, masking is the obscuring of 
sounds of interest by other sounds, often at similar frequencies. There 
are fewer data available regarding the potential impacts of masking on 
pinnipeds than on cetaceans. Cummings et al. (1984) subjected breeding 
ringed seals to recordings of industrial sounds. The authors did not 
document any impacts to ringed seal vocalizations as a result of 
exposure to the recordings.
    During the ice-covered season, only ringed seals and small numbers 
of bearded seals are found near Northstar. Therefore, there would be no 
masking effects on spotted seals, as they do not occur in the area 
during that time. All three pinniped species can be found in and around 
Northstar during the summer open-water season. As stated previously in 
this document, sounds from oil production and any drilling activities 
are not expected to be detectable beyond several kilometers from the 
source; however, sounds from vessels were detectable to distances as 
far as approximately 18.6 mi (30 km) from Northstar. There is the 
potential for vessels to cause some degree of masking.
    It is expected that masking of calls or other natural sounds would 
not extend beyond the maximum distance where the construction or 
operational sounds are detectable, and, at that distance, only the 
weakest sounds would be masked. The maximum distances for masking will 
vary greatly depending on ambient noise and sound propagation 
conditions but will typically be about 1.2-3.1 mi (2-5 km) in air and 
1.9-6.2 mi (3-10 km) underwater. Also, some types of Northstar sounds 
(especially the stronger ones) vary over time, and, at quieter times, 
masking would be absent or limited to closer distances. While some 
masking is possible, it is usually more prominent for lower 
frequencies. Although the functional hearing range for pinnipeds is 
estimated to occur between approximately 75 Hz and 75 kHz, the range 
with the greatest sensitivity is estimated to occur between 
approximately 700 Hz and 20 kHz. Therefore, BP's proposed activities 
are expected to have minor masking effects on pinnipeds.
(2) Behavioral Disturbance
    As stated earlier in this document, disturbance can induce a 
variety of effects, such as subtle changes in behavior, more 
conspicuous dramatic changes in activities, and displacement. When the 
received level of noise exceeds some behavioral reaction threshold, it 
is possible that some pinnipeds could exhibit disturbance reactions. 
The levels, frequencies and types of noise that elicit a response vary 
among and within species, individuals, locations, and seasons. 
Behavioral changes may be an upright posture for hauled out seals, 
movement away from the sound source, or complete avoidance of the area. 
The reaction threshold and degree of response are related to the 
activity of the animal at the time of the disturbance. Some researchers 
have noted that behavioral reactions do not occur throughout the entire 
zone ensonified by industrial activity. In most cases that have been 
studied, including recent work on ringed seals, the actual radius of 
effect is smaller than the radius of detectability (reviewed in 
Richardson et al., 1995b; Moulton et al., 2003a, 2005; Blackwell et 
al., 2004a).
    Effects of Construction, Drilling, and Production Activity--
Systematic aerial surveys to assess ringed seal responses to the 
construction of Seal Island were done both for Shell Oil (Green and 
Johnson, 1983) and for the Minerals Management Service, now the Bureau 
of Ocean Energy Management, Regulation and Enforcement (Frost and 
Burns, 1989; Kelly et al., 1988). Green and Johnson (1983) found that 
some seals within several kilometers of Seal Island were apparently 
displaced by construction of the island during the winter of 1981-82. 
Similarly, Frost and Lowry (1988) found lower densities of seals within 
2.3 mi (3.7 km) of artificial islands than in a zone 2.3-4.6 mi (3.7-
7.4 km) away when exploration activity was high. During years with 
construction or drilling activities, there was a 38-40% reduction in 
seal densities near the islands (Frost and Lowry, 1988). However, these 
early analyses did not account for non-industrial factors known to 
influence basking activity of seals (Moulton et al., 2002, 2005). Also, 
the numbers of sightings were small relative to the variation in the 
data.
    Kelly et al. (1988) used trained dogs to study the use by seals of 
breathing holes and lairs in relation to exposure to industrial 
activities. They reported that the proportion of structures abandoned 
within 5 mi (8 km) of Seal Island was similar to that within 492 ft 
(150 m) of on-ice seismic lines. There were no differences in 
abandonment rate within or beyond 492 ft (150 m) from Seal Island. 
Kelly et al. (1988) indicated that the data were not adequate to 
evaluate at what distances

[[Page 39720]]

from the island abandonment of structures began to decrease. In a final 
analysis of those data, Frost and Burns (1989) reported that the 
proportion of abandoned structures was significantly higher within 1.2 
mi (2 km) of Seal Island than 1.2-6.2 mi (2-10 km) away. Complicating 
the interpretation is that dog-based searches were conducted where 
structures were expected to be found, rather than over the entire study 
area, and multiple searches over a given area were not conducted. 
Hammill and Smith (1990) found that dogs missed as many as 73% of the 
structures during the first search of an area. Frost and Burns (1989) 
also noted that the analyses of disturbance and abandonment as a result 
of Seal Island construction were complicated by other noise sources 
that were active at the same time. These included on-ice seismic 
exploration, excavation of structures by their investigations, and snow 
machine traffic. Frost and Burns (1989) suspected that, overall, there 
was no area-wide increase in abandonment of structures. Finally, it is 
unknown whether there are differences in detection rates by dogs for 
open versus abandoned structures or for areas of different structure 
density. This detection bias potentially confounds interpretation of 
the data.
    Utilizing radio telemetry to examine the short-term behavioral 
responses of ringed seals to human activities, Kelly et al. (1988) 
found that some ringed seals temporarily departed from lairs when 
various sources of noise were within 97-3,000 m (0.06-1.9 mi) of an 
occupied structure. Radio-tagged ringed seals did return to re-occupy 
those lairs. However, the authors did not note the amount of time it 
took the ringed seals to re-occupy the lairs. The durations of haul-out 
bouts during periods with and without disturbance were not 
significantly different. Also, the time ringed seals spent in the water 
after disturbance did not differ significantly from that during periods 
of no disturbance (Kelly et al., 1988). Kelly et al. (1988) observed 
that rates of ringed seal abandonment of lairs were three times higher 
in areas with noise disturbance than in areas without noise 
disturbance. However, the abandonment rates in areas with noise 
disturbance were similar to rates of disturbance in areas of frequent 
predator activity (e.g., polar bears trying to break into lairs).
    Moulton et al. (2003a, 2005) conducted intensive and replicated 
aerial surveys during the springs of 1997-1999 (prior to the 
construction of Northstar) and 2000-2002 (with Northstar activities) to 
study the distribution and abundance of ringed seals within an 
approximately 1,598 mi\2\ (4,140 km\2\) area around the Northstar 
Development. The main objective was to determine whether, and to what 
extent, oil development affected the local distribution and abundance 
of ringed seals. The 1997-1999 surveys were conducted coincidentally 
with aerial surveys over a larger area of the central Beaufort Sea 
(Frost et al., 2004). Moulton et al. (2003a, 2005) determined that the 
raw density of ringed seals over their study area ranged from 0.39 to 
0.83 seals/km\2\, while Frost et al. (2004) obtained raw densities of 
0.64 to 0.87 seals/km\2\ in a similar area at about the same times. 
There was no evidence that construction, drilling, and production 
activities at Northstar in 2000-2002 significantly affected local 
ringed seal distribution and abundance relative to the baseline years 
(1997-1999). Additionally, after natural variables that affect haul-out 
behavior were considered (Moulton et al., 2003a, 2005), there was no 
significant evidence of reduced seal densities close to Northstar as 
compared with farther away during the springs of 2000, 2001, and 2002. 
The survey methods and associated analyses were shown to have high 
statistical power to detect such changes if they occurred. 
Environmental factors such as date, water depth, degree of ice 
deformation, presence of meltwater, and percent cloud cover had more 
conspicuous and statistically-significant effects on seal sighting 
rates than did any human-related factors (Moulton et al., 2003a, 2005).
    To complement the aerial survey program on a finer scale, 
specially-trained dogs were used to find seal structures and to monitor 
the fate of structures in relation to distance from industrial 
activities (Williams et al., 2006c). In late 2000, surveys began before 
construction of ice roads but concurrent with drilling and other island 
activities. In the winter of 2000-2001, a total of 181 structures were 
located, of which 118 (65%) were actively used by late May 2001. 
However, there was no relationship between structure survival or the 
proportion of structures abandoned and distance to Northstar-related 
activities. The most important factors predicting structure survival 
were time of year when found and ice deformation. The covariate 
distance to the ice road improved the fit of the model, but the 
relationship indicated that structure survival was lower farther away 
from the ice road, contrary to expectation. However, new structures 
found after the ice road was constructed were, on average, farther from 
the ice road than were structures found before construction (though 
this was marginally statistically significant). This may have been 
related to the active flooding of the ice road, which effectively 
removed some of the ice as potential ringed seal habitat.
    Blackwell et al. (2004a) investigated the effects of noise from 
pipe-driving and other construction activities on Northstar to ringed 
seals in June and July 2000, during and just after break-up of the 
landfast ice. None of the ringed seals seen during monitoring showed 
any strong reactions to the pipe-driving or other construction 
activities on Northstar. Eleven of the seals (48%) appeared either 
indifferent or curious when exposed to construction or pipe-driving 
sounds. One seal approached within 9.8 ft (3 m) of the island's edge 
during pipe-driving and others swam in the 9.8-49.2 ft (3-15 m) moat 
around the island. Seals in the moat may have been exposed to sound 
levels up to 153-160 dB re 1 [micro]Pa (rms) when they dove close to 
the bottom.
    Consistent with Blackwell et al. (2004a), seals are often very 
tolerant of exposure to other types of pulsed sounds. For example, 
seals tolerate high received levels of sounds from airgun arrays 
(Arnold, 1996; Harris et al., 2001; Moulton and Lawson, 2002). 
Monitoring work in the Alaskan Beaufort Sea during 1996-2001 provided 
considerable information regarding the behavior of seals exposed to 
seismic pulses (Harris et al., 2001; Moulton and Lawson, 2002). These 
seismic projects usually involved arrays of 6 to 16 airguns with total 
volumes of 560 to 1,500 in\3\ (0.01 to 0.03 m\3\). The combined results 
suggest that some seals avoid the immediate area around seismic 
vessels. In most survey years, ringed seal sightings tended to be 
farther away from the seismic vessel when the airguns were operating 
than when they were not (Moulton and Lawson, 2002). However, these 
avoidance movements were relatively small, on the order of 328 ft (100 
m) to a few hundreds of meters, and many seals remained within 328-656 
ft (100-200 m) of the trackline as the operating airgun array passed 
by. Seal sighting rates at the water surface were lower during airgun 
array operations than during no-airgun periods in each survey year 
except 1997. Similarly, seals are often very tolerant of pulsed sounds 
from seal-scaring devices (Mate and Harvey, 1987; Jefferson and Curry, 
1994; Richardson et al., 1995b). Therefore, the short distance for 
avoidance reactions to impulsive pile driving sounds from the pile 
driving operations on Northstar is consistent with these other data.

[[Page 39721]]

    Effects of Aircraft Activity--Helicopters are the only aircraft 
associated with Northstar oil production activities. Helicopter traffic 
occurs primarily during late spring and autumn when travel by ice road, 
hovercraft, or vessel is not possible.
    Potential effects to pinnipeds from aircraft activity could involve 
both acoustic and non-acoustic effects. It is uncertain if the seals 
react to the sound of the helicopter or to its physical presence flying 
overhead. Typical reactions of hauled out pinnipeds to aircraft that 
have been observed include looking up at the aircraft, moving on the 
ice or land, entering a breathing hole or crack in the ice, or entering 
the water. Ice seals hauled out on the ice have been observed diving 
into the water when approached by a low-flying aircraft or helicopter 
(Burns and Harbo, 1972, cited in Richardson et al., 1995b; Burns and 
Frost, 1979, cited in Richardson et al., 1995b). Richardson et al. 
(1995b) note that responses can vary based on differences in aircraft 
type, altitude, and flight pattern. Additionally, a study conducted by 
Born et al. (1999) found that wind chill was also a factor in level of 
response of ringed seals hauled out on ice, as well as time of day and 
relative wind direction.
    Blackwell et al. (2004a) observed 12 ringed seals during low-
altitude overflights of a Bell 212 helicopter at Northstar in June and 
July 2000 (9 observations took place concurrent with pipe-driving 
activities). One seal showed no reaction to the aircraft while the 
remaining 11 (92%) reacted, either by looking at the helicopter (n=10) 
or by departing from their basking site (n=1). Blackwell et al. (2004a) 
concluded that none of the reactions to helicopters were strong or long 
lasting, and that seals near Northstar in June and July 2000 probably 
had habituated to industrial sounds and visible activities that had 
occurred often during the preceding winter and spring. There have been 
few systematic studies of pinniped reactions to aircraft overflights, 
and most of the available data concern pinnipeds hauled out on land or 
ice rather than pinnipeds in the water (Richardson et al., 1995b; Born 
et al., 1999).
    Born et al. (1999) determined that 49% of ringed seals escaped 
(i.e., left the ice) as a response to a helicopter flying at 492 ft 
(150 m) altitude. Seals entered the water when the helicopter was 4,101 
ft (1,250 m) away if the seal was in front of the helicopter and at 
1,640 ft (500 m) away if the seal was to the side of the helicopter. 
The authors noted that more seals reacted to helicopters than to fixed-
wing aircraft. The study concluded that the risk of scaring ringed 
seals by small-type helicopters could be substantially reduced if they 
do not approach closer than 4,921 ft (1,500 m).
    Spotted seals hauled out on land in summer are unusually sensitive 
to aircraft overflights compared to other species. They often rush into 
the water when an aircraft flies by at altitudes up to 984-2,461 ft 
(300-750 m). They occasionally react to aircraft flying as high as 
4,495 ft (1,370 m) and at lateral distances as far as 1.2 mi (2 km) or 
more (Frost and Lowry, 1990; Rugh et al., 1997). However, no spotted 
seal haul-outs are located near Northstar.
    Effects of Vessel Activity--Few authors have specifically described 
the responses of pinnipeds to boats, and most of the available 
information on reactions to boats concerns pinnipeds hauled out on land 
or ice. Ringed seals hauled out on ice pans often showed short-term 
escape reactions when a ship approached the animal within 0.16 to 0.31 
mi (0.25 to 0.5 km; Brueggeman et al., 1992). Jansen et al. (2006) 
reported that harbor seals approached by vessels within 328 ft (100 m) 
were 25 times more likely to enter the water than were seals approached 
at 1,640 ft (500 m). However, during the open water season in the 
Beaufort Sea, ringed and bearded seals are commonly observed close to 
vessels (Harris et al., 2001; Moulton and Lawson, 2002).
    In places where boat traffic is heavy, there have been cases where 
seals have habituated to vessel disturbance. In England, harbor and 
gray seals at specific haul-outs appear to have habituated to close 
approaches by tour boats (Bonner, 1982). Jansen et al. (2006) found 
that harbor seals in Disenchantment Bay, Alaska, increased in abundance 
during the summer as ship traffic also increased. In Maine, Lelli and 
Harris (2001) found that boat traffic was the best predictor of 
variability in harbor seal haulout behavior, followed by wave height 
and percent sunshine, utilizing multiple regressions. Lelli and Harris 
(2001) reported that increasing boat traffic reduced the number of 
seals counted on the haul-out. Suryan and Harvey (1999) reported that 
Pacific harbor seals commonly left the shore when powerboat operators 
approached to observe the seals. Those seals detected a powerboat at a 
mean distance of 866 ft (264 m), and seals left the haul-out site when 
boats approached to within 472 ft (144 m). Southall et al. (2007) 
report that pinnipeds exposed to sounds at approximately 110 to 120 dB 
re 20 [mu]Pa in-air tended to respond by leaving their haul-outs and 
seeking refuge in the water, while animals exposed to in-air sounds of 
approximately 60 to 70 dB re 20 [mu]Pa often did not respond at all.
(3) Hearing Impairment and Other Physiological Effects
    Pinnipeds are able to hear both in-water and in-air sounds. 
However, they have significantly different hearing capabilities in the 
two media. Temporary or permanent hearing impairment is a possibility 
when marine mammals are exposed to very strong sounds. Non-auditory 
physiological effects might also occur in marine mammals exposed to 
strong underwater sound. Possible types of non-auditory physiological 
effects or injuries that theoretically might occur in mammals close to 
a strong sound source include stress, neurological effects, bubble 
formation, and other types of organ or tissue damage. Pinnipeds are not 
anticipated to experience non-auditory physiological effects as a 
result of operation of the Northstar facility, as none of the 
activities associated with the facility will generate sounds loud 
enough to cause such effects.
    TTS--As stated earlier in this document, TTS is the mildest form of 
hearing impairment that can occur during exposure to a strong sound 
(Kryter, 1985). For additional background about TTS, please refer to 
the discussion on impacts to cetaceans from sound found earlier in this 
section of the document.
    As stated earlier in this document, the functional hearing range 
for pinnipeds in-air is 75 Hz to 30 kHz (Southall et al., 2007). 
Richardson et al. (1995b) note that dominant tones in noise spectra 
from both helicopters and fixed-wing aircraft are generally below 500 
Hz. Kastak and Schustermann (1995) state that the in-air hearing 
sensitivity is less than the in-water hearing sensitivity for 
pinnipeds. In-air hearing sensitivity deteriorates as frequency 
decreases below 2 kHz, and generally pinnipeds appear to be 
considerably less sensitive to airborne sounds below 10 kHz than 
humans. There is a dearth of information on the acoustic effects of 
helicopter overflights on pinniped hearing and communication 
(Richardson et al., 1995b), and, to NMFS' knowledge, there has been no 
specific documentation of TTS in free-ranging pinnipeds exposed to 
helicopter operations during realistic field conditions.
    In free-ranging pinnipeds, TTS thresholds associated with exposure 
to brief pulses (single or multiple) of underwater sound have not been 
measured. However, systematic TTS studies on captive pinnipeds have 
been conducted (Bowles et al., 1999; Kastak

[[Page 39722]]

et al., 1999, 2005, 2007; Schusterman et al., 2000; Finneran et al., 
2003; Southall et al., 2007). Kastak et al. (1999) reported TTS of 
approximately 4-5 dB in three species of pinnipeds (harbor seal, 
California sea lion, and northern elephant seal) after underwater 
exposure for approximately 20 minutes to noise with frequencies ranging 
from 100-2,000 Hz at received levels 60-75 dB above hearing threshold. 
This approach allowed similar effective exposure conditions to each of 
the subjects, but resulted in variable absolute exposure values 
depending on subject and test frequency. Recovery to near baseline 
levels was reported within 24 hours of noise exposure (Kastak et al., 
1999). Kastak et al. (2005) followed up on their previous work using 
higher sensitivity levels and longer exposure times (up to 50 min) and 
corroborated their previous findings. The sound exposures necessary to 
cause slight threshold shifts were also determined for two California 
sea lions and a juvenile elephant seal exposed to underwater sound for 
a similar duration. The sound level necessary to cause TTS in pinnipeds 
depends on exposure duration, as in other mammals; with longer 
exposure, the level necessary to elicit TTS is reduced (Schusterman et 
al., 2000; Kastak et al., 2005, 2007). For very short exposures (e.g., 
to a single sound pulse), the level necessary to cause TTS is very high 
(Finneran et al., 2003). For pinnipeds exposed to in-air sounds, 
auditory fatigue has been measured in response to single pulses and to 
non-pulse noise (Southall et al., 2007), although high exposure levels 
were required to induce TTS-onset (SEL: 129 dB re: 20 [mu]Pa\2.\s; 
Bowles et al., unpub. data).
    NMFS (1995, 2000) concluded that pinnipeds should not be exposed to 
pulsed underwater noise at received levels exceeding 190 dB re 1 [mu]Pa 
(rms). The established 190-dB re 1 [mu]Pa (rms) criterion is not 
considered to be the level above which TTS might occur in pinnipeds. 
Rather, it is the received level 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 
pinnipeds. Levels of underwater sound from production and drilling 
activities that occur continuously over extended periods at Northstar 
are not very high (Blackwell and Greene, 2006). For example, received 
levels of prolonged drilling sounds are expected to diminish below 140 
dB re 1 [mu]Pa at a distance of about 131 ft (40 m) from the center of 
activity. Sound levels during other production activities aside from 
drilling usually would diminish below 140 dB re 1 [mu]Pa at a closer 
distance. The 140 dB re 1 [mu]Pa radius for drilling noise is within 
the island and drilling sounds are attenuated to levels below 140 dB re 
1 [mu]Pa in the water near Northstar. Therefore, TTS is not expected 
from the operations at Northstar.
    PTS--As stated earlier in this document, when PTS occurs, there is 
physical damage to the sound receptors in the ear. For additional 
background about PTS, please refer to the discussion with respect to 
impacts from sound on cetaceans found earlier in this section of the 
document.
    It is highly unlikely that pinnipeds could receive sounds strong 
enough (and over a sufficient duration) to cause PTS (or even TTS) 
during the proposed operation of the Northstar facility. Source levels 
for much of the equipment used at Northstar do not reach the threshold 
of 190 dB currently used for pinnipeds. Based on this conclusion, it is 
highly unlikely that any type of hearing impairment, temporary or 
permanent, would occur as a result of BP's proposed activities. 
Additionally, Southall et al. (2007) proposed that the thresholds for 
injury of marine mammals exposed to ``discrete'' noise events (either 
single or multiple exposures over a 24-hr period) are higher than the 
190-dB re 1 [mu]Pa (rms) in-water threshold currently used by NMFS. 
Table 2 in this document summarizes the SPL and SEL levels thought to 
cause auditory injury to pinnipeds both in-water and in-air. For more 
information, please refer to Southall et al. (2007).

 Table 2--Proposed Injury Criteria for Pinnipeds Exposed to ``Discrete'' Noise Events (Either Single Pulses, Multiple Pulses, or Non-Pulses Within a 24-
                                                            Hr Period; Southall et al., 2007)
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                            Single pulses                           Multiple pulses                             Non pulses
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                  Pinnipeds (in water)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Sound pressure level.........  218 dB re 1 [micro]Pa (peak) (flat)      218 dB re 1 [micro]Pa (peak) (flat)      218 dB re 1 [micro]Pa (peak) (flat)
Sound exposure level.........  186 dB re 1 [micro]Pa\2\-s (Mpw)         186 dB re 1 [micro]Pa\2\-s (Mpw)         203 dB re 1 [micro]Pa\2\-s (Mpw)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Pinnipeds (in air)......................................................................................................................................
--------------------------------------------------------------------------------------------------------------------------------------------------------
Sound pressure level.........  149 dB re 20 [micro]Pa (peak) (flat)     149 dB re 20 [micro]Pa (peak) (flat)     149 dB re 20 [micro]Pa (peak) (flat)
Sound exposure level.........  144 dB re (20 [micro]Pa)\2\-s (Mpa)      144 dB re (20 [micro]Pa)\2\-s (Mpa)      144.5 dB re (20 [micro]Pa)\2\-s (Mpa)
--------------------------------------------------------------------------------------------------------------------------------------------------------

Potential Effects of Oil on Cetaceans

    The specific effects an oil spill would have on bowhead, gray, or 
beluga whales are not well known. While direct mortality is unlikely, 
exposure to spilled oil could lead to skin irritation, baleen fouling 
(which might reduce feeding efficiency), respiratory distress from 
inhalation of hydrocarbon vapors, consumption of some contaminated prey 
items, and temporary displacement from contaminated feeding areas. 
Geraci and St. Aubin (1990) summarize effects of oil on marine mammals, 
and Bratton et al. (1993) provides a synthesis of knowledge of oil 
effects on bowhead whales. The number of whales that might be contacted 
by a spill would depend on the size, timing, and duration of the spill. 
Whales may not avoid oil spills, and some have been observed feeding 
within oil slicks (Goodale et al., 1981). These topics are discussed in 
more detail next.
    In the case of an oil spill occurring during migration periods, 
disturbance of the migrating cetaceans from cleanup activities may have 
more of an impact than the oil itself. Human activity associated with 
cleanup efforts could deflect whales away from the path of the oil. 
However, noise created from cleanup activities likely will be short 
term and localized. In fact, whale avoidance of clean-up activities may 
benefit whales by displacing them from the oil spill area.
    There is no concrete evidence that oil spills, including the much 
studied Santa Barbara Channel and Exxon Valdez spills, have caused any 
deaths of cetaceans (Geraci, 1990; Brownell, 1971;

[[Page 39723]]

Harvey and Dahlheim, 1994). It is suspected that some individually 
identified killer whales that disappeared from Prince William Sound 
during the time of the Exxon Valdez spill were casualties of that 
spill. However, no clear cause and effect relationship between the 
spill and the disappearance could be established (Dahlheim and Matkin, 
1994). The AT-1 pod of transient killer whales that sometimes inhabits 
Prince William Sound has continued to decline after the Exxon Valdez 
oil spill (EVOS). Matkin et al. (2008) tracked the AB resident pod and 
the AT-1 transient group of killer whales from 1984 to 2005. The 
results of their photographic surveillance indicate a much higher than 
usual mortality rate for both populations the year following the spill 
(33% for AB Pod and 41% for AT-1 Group) and lower than average rates of 
increase in the 16 years after the spill (annual increase of about 1.6% 
for AB Pod compared to an annual increase of about 3.2% for other 
Alaska killer whale pods). In killer whale pods, mortality rates are 
usually higher for non-reproductive animals and very low for 
reproductive animals and adolescents (Olesiuk et al., 1990, 2005; 
Matkin et al., 2005). No effects on humpback whales in Prince William 
Sound were evident after the Exxon Valdez spill (von Ziegesar et al., 
1994). There was some temporary displacement of humpback whales out of 
Prince William Sound, but this could have been caused by oil 
contamination, boat and aircraft disturbance, displacement of food 
sources, or other causes.
    Migrating gray whales were apparently not greatly affected by the 
Santa Barbara spill of 1969. There appeared to be no relationship 
between the spill and mortality of marine mammals. The higher than 
usual counts of dead marine mammals recorded after the spill 
represented increased survey effort and therefore cannot be 
conclusively linked to the spill itself (Brownell, 1971; Geraci, 1990). 
The conclusion was that whales were either able to detect the oil and 
avoid it or were unaffected by it (Geraci, 1990).
(1) Oiling of External Surfaces
    Whales rely on a layer of blubber for insulation, so oil would have 
little if any effect on thermoregulation by whales. Effects of oiling 
on cetacean skin appear to be minor and of little significance to the 
animal's health (Geraci, 1990). Histological data and ultrastructural 
studies by Geraci and St. Aubin (1990) showed that exposures of skin to 
crude oil for up to 45 minutes in four species of toothed whales had no 
effect. They switched to gasoline and applied the sponge up to 75 
minutes. This produced transient damage to epidermal cells in whales. 
Subtle changes were evident only at the cell level. In each case, the 
skin damage healed within a week. They concluded that a cetacean's skin 
is an effective barrier to the noxious substances in petroleum. These 
substances normally damage skin by getting between cells and dissolving 
protective lipids. In cetacean skin, however, tight intercellular 
bridges, vital surface cells, and the extraordinary thickness of the 
epidermis impeded the damage. The authors could not detect a change in 
lipid concentration between and within cells after exposing skin from a 
white-sided dolphin to gasoline for 16 hours in vitro.
    Bratton et al. (1993) synthesized studies on the potential effects 
of contaminants on bowhead whales. They concluded that no published 
data proved oil fouling of the skin of any free-living whales, and 
conclude that bowhead whales contacting fresh or weathered petroleum 
are unlikely to suffer harm. Although oil is unlikely to adhere to 
smooth skin, it may stick to rough areas on the surface (Henk and 
Mullan, 1997). Haldiman et al. (1985) found the epidermal layer to be 
as much as seven to eight times thicker than that found on most whales. 
They also found that little or no crude oil adhered to preserved 
bowhead skin that was dipped into oil up to three times, as long as a 
water film stayed on the skin's surface. Oil adhered in small patches 
to the surface and vibrissae (stiff, hairlike structures), once it made 
enough contact with the skin. The amount of oil sticking to the 
surrounding skin and epidermal depression appeared to be in proportion 
to the number of exposures and the roughness of the skin's surface. It 
can be assumed that if oil contacted the eyes, effects would be similar 
to those observed in ringed seals; continued exposure of the eyes to 
oil could cause permanent damage (St. Aubin, 1990).
(2) Ingestion
    Whales could ingest oil if their food is contaminated, or oil could 
also be absorbed through the respiratory tract. Some of the ingested 
oil is voided in vomit or feces but some is absorbed and could cause 
toxic effects (Geraci, 1990). When returned to clean water, 
contaminated animals can depurate this internal oil (Engelhardt, 1978, 
1982). Oil ingestion can decrease food assimilation of prey eaten (St. 
Aubin, 1988). Cetaceans may swallow some oil-contaminated prey, but it 
likely would be only a small part of their food. It is not known if 
whales would leave a feeding area where prey was abundant following a 
spill. Some zooplankton eaten by bowheads and gray whales consume oil 
particles and bioaccumulation can result. Tissue studies by Geraci and 
St. Aubin (1990) revealed low levels of naphthalene in the livers and 
blubber of baleen whales. This result suggests that prey have low 
concentrations in their tissues, or that baleen whales may be able to 
metabolize and excrete certain petroleum hydrocarbons. Whales exposed 
to an oil spill are unlikely to ingest enough oil to cause serious 
internal damage (Geraci and St. Aubin, 1980, 1982) and this kind of 
damage has not been reported (Geraci, 1990).
(3) Fouling of Baleen
    Baleen itself is not damaged by exposure to oil and is resistant to 
effects of oil (St. Aubin et al., 1984). Crude oil could coat the 
baleen and reduce filtration efficiency; however, effects may be 
temporary (Braithwaite, 1983; St. Aubin et al., 1984). If baleen is 
coated in oil for long periods, it could cause the animal to be unable 
to feed, which could lead to malnutrition or even death. Most of the 
oil that would coat the baleen is removed after 30 min, and less than 
5% would remain after 24 h (Bratton et al., 1993). Effects of oiling of 
the baleen on feeding efficiency appear to be minor (Geraci, 1990). 
However, a study conducted by Lambertsen et al. (2005) concluded that 
their results highlight the uncertainty about how rapidly oil would 
depurate at the near zero temperatures in arctic waters and whether 
baleen function would be restored after oiling.
(4) Avoidance
    Some cetaceans can detect oil and sometimes avoid it, but others 
enter and swim through slicks without apparent effects (Geraci, 1990; 
Harvey and Dahlheim, 1994). Bottlenose dolphins apparently could detect 
and avoid slicks and mousse but did not avoid light sheens on the 
surface (Smultea and Wursig, 1995). After the Regal Sword spill in 
1979, various species of baleen and toothed whales were observed 
swimming and feeding in areas containing spilled oil southeast of Cape 
Cod, MA (Goodale et al., 1981). For months following EVOS, there were 
numerous observations of gray whales, harbor porpoises, Dall's 
porpoises, and killer whales swimming through light-to-heavy crude-oil 
sheens (Harvey and Dalheim, 1994, cited in Matkin et al., 2008). 
However, if some of the animals avoid the area because of the oil, then

[[Page 39724]]

the effects of the oiling would be less severe on those individuals.
(5) Factors Affecting the Severity of Effects
    Effects of oil on whales in open water are likely to be minimal, 
but there could be effects on whales where both the oil and the whales 
are at least partly confined in leads or at ice edges (Geraci, 1990). 
In spring, bowhead and beluga whales migrate through leads in the ice. 
At this time, the migration can be concentrated in narrow corridors 
defined by the leads, thereby creating a greater risk to animals caught 
in the spring lead system should oil enter the leads. However, given 
the probable alongshore trajectory of oil spilled from Northstar in 
relation to the whale migration route through offshore waters, 
interactions between oil slicks and whales are unlikely in spring, as 
any spilled oil would likely remain closer to shore.
    In fall, the migration route of bowheads can be close to shore 
(Blackwell et al., 2009). If fall migrants were moving through leads in 
the pack ice or were concentrated in nearshore waters, some bowhead 
whales might not be able to avoid oil slicks and could be subject to 
prolonged contamination. However, the autumn migration past the 
Northstar area extends over several weeks, and many of the whales 
travel along routes well north of Northstar. Thus, only a small portion 
of the whales are likely to approach patches of spilled oil. 
Additionally, vessel activity associated with spill cleanup efforts may 
deflect the small number of whales traveling nearshore farther 
offshore, thereby reducing the likelihood of contact with spilled oil. 
Also, during years when movements of oil and whales might be partially 
confined by ice, the bowhead migration corridor tends to be farther 
offshore (Treacy, 1997; LGL and Greeneridge, 1996a; Moore, 2000).
    Bowhead and beluga whales overwinter in the Bering Sea (mainly from 
November to March). In the summer, the majority of the bowhead whales 
are found in the Canadian Beaufort Sea, although some have recently 
been observed in the U.S. Beaufort and Chukchi Seas during the summer 
months (June to August). Data from the Barrow-based boat surveys in 
2009 (George and Sheffield, 2009) showed that bowheads were observed 
almost continuously in the waters near Barrow, including feeding groups 
in the Chukchi Sea at the beginning of July. The majority of belugas in 
the Beaufort stock migrate into the Beaufort Sea in April or May, 
although some whales may pass Point Barrow as early as late March and 
as late as July (Braham et al., 1984; Ljungblad et al., 1984; 
Richardson et al., 1995b). Therefore, a spill in winter or summer would 
not be expected to have major impacts on these species. Additionally, 
while gray whales have commonly been sighted near Point Barrow, they 
are much less frequently found in the Prudhoe Bay area. Therefore, an 
oil spill is not expected to have major impacts to gray whales.
(6) Effects of Oil-Spill Cleanup Activities
    Oil spill cleanup activities could increase disturbance effects on 
either whales or seals, causing temporary disruption and possible 
displacement (MMS, 1996). The Northstar Oil Discharge Prevention and 
Contingency Plan (ODPCP; BPXA, 1998a, b) includes a scenario of a 
production well blowout to the open-water in August. In this scenario, 
approximately 177,900 barrels of North Slope crude oil will reach the 
open-water. It is estimated that response activities would require 186 
staff (93 per shift) using 33 vessels (see Table 1.6.1-3 in BPXA, 
1998b) for about 15 days to recover oil in open-water. Shoreline 
cleanup would occur for approximately 45 days employing low pressure, 
cold water deluge on the soiled shorelines. In a similar scenario 
during solid ice conditions, it is estimated that 97 pieces of 
equipment along with 246 staff (123 per shift) would be required for 
response activities (BPXA, 1998a).
    The potential effects on cetaceans are expected to be less than 
those on seals (described later in this section of the document). 
Cetaceans tend to occur well offshore where cleanup activities (in the 
open-water season) are unlikely to be as concentrated. Also, cetaceans 
are transient and, during the majority of the year, absent from the 
area. However, if intensive cleanup activities were necessary during 
the autumn whale hunt, this could affect subsistence hunting. Impacts 
to subsistence uses of marine mammals are discussed later in this 
document (see the ``Impact on Availability of Affected Species or Stock 
for Taking for Subsistence Uses'' section).

Potential Effects of Oil on Pinnipeds

    Ringed, bearded, and spotted seals are present in open-water areas 
during summer and early autumn, and ringed seals remain in the area 
through the ice-covered season. During the spring periods in 1997-2002, 
the observed densities of ringed seals on the fast-ice in areas greater 
than 9.8 ft (3 m) deep ranged from 0.35 to 0.72 seals/km\2\. After 
allowance for seals not seen by aerial surveyors, actual densities may 
have been about 2.84 times higher (Moulton et al., 2003a). Therefore, 
an oil spill from the Northstar development or its pipeline could 
affect seals. Any oil spilled under the ice also has the potential to 
directly contact seals.
    Externally oiled phocid seals often survive and become clean, but 
heavily oiled seal pups and adults may die, depending on the extent of 
oiling and characteristics of the oil. Prolonged exposure could occur 
if fuel or crude oil was spilled in or reached nearshore waters, was 
spilled in a lead used by seals, or was spilled under the ice when 
seals have limited mobility (NMFS, 2000). Adult seals may suffer some 
temporary adverse effects, such as eye and skin irritation, with 
possible infection (MMS, 1996). Such effects may increase stress, which 
could contribute to the death of some individuals. Ringed seals may 
ingest oil-contaminated foods, but there is little evidence that oiled 
seals will ingest enough oil to cause lethal internal effects. There is 
a likelihood that newborn seal pups, if contacted by oil, would die 
from oiling through loss of insulation and resulting hypothermia. These 
potential effects are addressed in more detail in subsequent 
paragraphs.
    Reports of the effects of oil spills have shown that some mortality 
of seals may have occurred as a result of oil fouling; however, large 
scale mortality had not been observed prior to the EVOS (St. Aubin, 
1990). Effects of oil on marine mammals were not well studied at most 
spills because of lack of baseline data and/or the brevity of the post-
spill surveys. The largest documented impact of a spill, prior to EVOS, 
was on young seals in January in the Gulf of St. Lawrence (St. Aubin, 
1990). Brownell and Le Boeuf (1971) found no marked effects of oil from 
the Santa Barbara oil spill on California sea lions or on the mortality 
rates of newborn pups.
    Intensive and long-term studies were conducted after the EVOS in 
Alaska. There may have been a long-term decline of 36% in numbers of 
molting harbor seals at oiled haul-out sites in Prince William Sound 
following EVOS (Frost et al., 1994a). However, in a reanalysis of those 
data and additional years of surveys, along with an examination of 
assumptions and biases associated with the original data, Hoover-Miller 
et al. (2001) concluded that the EVOS effect had been overestimated. 
The decline in attendance at some oiled sites was more likely a 
continuation of the general decline in harbor seal abundance in Prince 
William Sound documented since 1984 (Frost et al., 1999) than a

[[Page 39725]]

result of EVOS. The results from Hoover-Miller et al. (2001) indicate 
that the effects of EVOS were largely indistinguishable from natural 
decline by 1992. However, while Frost et al. (2004) concluded that 
there was no evidence that seals were displaced from oiled sites, they 
did find that aerial counts indicated 26% less pups were produced at 
oiled locations in 1989 than would have been expected without the oil 
spill. Harbor seal pup mortality at oiled beaches was 23% to 26%, which 
may have been higher than natural mortality, although no baseline data 
for pup mortality existed prior to EVOS (Frost et al., 1994a). There 
was no conclusive evidence of spill effects on Steller sea lions 
(Calkins et al., 1994). Oil did not persist on sea lions themselves (as 
it did on harbor seals), nor did it persist on sea lion haul-out sites 
and rookeries (Calkins et al., 1994). Sea lion rookeries and haul out 
sites, unlike those used by harbor seals, have steep sides and are 
subject to high wave energy (Calkins et al., 1994).
(1) Oiling of External Surfaces
    Adult seals rely on a layer of blubber for insulation, and oiling 
of the external surface does not appear to have adverse 
thermoregulatory effects (Kooyman et al., 1976, 1977; St. Aubin, 1990). 
Contact with oil on the external surfaces can potentially cause 
increased stress and irritation of the eyes of ringed seals (Geraci and 
Smith, 1976; St. Aubin, 1990). These effects seemed to be temporary and 
reversible, but continued exposure of eyes to oil could cause permanent 
damage (St. Aubin, 1990). Corneal ulcers and abrasions, conjunctivitis, 
and swollen nictitating membranes were observed in captive ringed seals 
placed in crude oil-covered water (Geraci and Smith, 1976), and in 
seals in the Antarctic after an oil spill (Lillie, 1954).
    Newborn seal pups rely on their fur for insulation. Newborn ringed 
seal pups in lairs on the ice could be contaminated through contact 
with oiled mothers. There is the potential that newborn ringed seal 
pups that were contaminated with oil could die from hypothermia.
(2) Ingestion
    Marine mammals can ingest oil if their food is contaminated. Oil 
can also be absorbed through the respiratory tract (Geraci and Smith, 
1976; Engelhardt et al., 1977). Some of the ingested oil is voided in 
vomit or feces but some is absorbed and could cause toxic effects 
(Engelhardt, 1981). When returned to clean water, contaminated animals 
can depurate this internal oil (Engelhardt, 1978, 1982, 1985). In 
addition, seals exposed to an oil spill are unlikely to ingest enough 
oil to cause serious internal damage (Geraci and St. Aubin, 1980, 
1982).
(3) Avoidance and Behavioral Effects
    Although seals may have the capability to detect and avoid oil, 
they apparently do so only to a limited extent (St. Aubin, 1990). Seals 
may abandon the area of an oil spill because of human disturbance 
associated with cleanup efforts, but they are most likely to remain in 
the area of the spill. One notable behavioral reaction to oiling is 
that oiled seals are reluctant to enter the water, even when intense 
cleanup activities are conducted nearby (St. Aubin, 1990; Frost et al., 
1994b, 2004).
(4) Factors Affecting the Severity of Effects
    Seals that are under natural stress, such as lack of food or a 
heavy infestation by parasites, could potentially die because of the 
additional stress of oiling (Geraci and Smith, 1976; St. Aubin, 1990; 
Spraker et al., 1994). Female seals that are nursing young would be 
under natural stress, as would molting seals. In both cases, the seals 
would have reduced food stores and may be less resistant to effects of 
oil than seals that are not under some type of natural stress. Seals 
that are not under natural stress (e.g., fasting, molting) would be 
more likely to survive oiling. In general, seals do not exhibit large 
behavioral or physiological reactions to limited surface oiling or 
incidental exposure to contaminated food or vapors (St. Aubin, 1990; 
Williams et al., 1994). Effects could be severe if seals surface in 
heavy oil slicks in leads or if oil accumulates near haul-out sites 
(St. Aubin, 1990). An oil spill in open-water is less likely to impact 
seals.
    Seals exposed to heavy doses of oil for prolonged periods could 
die. This type of prolonged exposure could occur if fuel or crude oil 
was spilled in or reached nearshore waters, was spilled in a lead used 
by seals, or was spilled under the ice in winter when seals have 
limited mobility. Seals residing in these habitats may not be able to 
avoid prolonged contamination and some could die. Impacts on regional 
populations of seals would be expected to be minor.
    Since ringed seals are found year-round in the U.S. Beaufort Sea 
and more specifically in the project area, an oil spill at any time of 
year could potentially have effects on ringed seals. However, they are 
more widely dispersed during the open-water season. Spotted seals are 
unlikely to be found in the project area during late winter and spring. 
Therefore, they are more likely to be affected by a spill in the summer 
or fall seasons. Bearded seals typically overwinter south of the 
Beaufort Sea. However, some have been reported around Northstar during 
early spring (Moulton et al., 2003b). Oil spills during the open-water 
period and fall are the most likely to impact bearded seals.
(5) Effects of Oil-Spill Cleanup Activities
    Oil spill cleanup activities could increase disturbance effects on 
either whales or seals, causing temporary disruption and possible 
displacement (MMS, 1996). General issues related to oil spill cleanup 
activities are discussed earlier in this section for cetaceans. In the 
event of a large spill contacting and extensively oiling coastal 
habitats, the presence of response staff, equipment, and the many 
aircraft involved in the cleanup could (depending on the time of the 
spill and the cleanup) potentially displace seals. If extensive cleanup 
operations occur in the spring, they could cause increased stress and 
reduced pup survival of ringed seals. Oil spill cleanup activity could 
exacerbate and increase disturbance effects on subsistence species, 
cause localized displacement of subsistence species, and alter or 
reduce access to those species by hunters. On the other hand, the 
displacement of marine mammals away from oil-contaminated areas by 
cleanup activities would reduce the likelihood of direct contact with 
oil. Impacts to subsistence uses of marine mammals are discussed later 
in this document (see the ``Impact on Availability of Affected Species 
or Stock for Taking for Subsistence Uses'' section).

Summary of Potential Effects on Marine Mammals

    The likely or possible impacts of the planned offshore oil 
developments at Northstar on marine mammals involve both non-acoustic 
and acoustic effects. Potential non-acoustic effects are most likely to 
impact pinnipeds in the area through temporary displacement from haul-
out areas near the Northstar facility. There is a small chance that a 
seal pup might be injured or killed by on-ice construction or 
transportation activities. A major oil spill is unlikely and, if it 
occurred, its effects are difficult to predict. A major oil spill might 
cause serious injury or mortality to small numbers of marine mammals by 
impacting the animals' ability to eat or find uncontaminated prey or by 
causing respiratory distress from

[[Page 39726]]

inhalation of hydrocarbon vapors. Oiled newborn seal pups could also 
die from hypothermia. However, BP has an oil spill contingency and 
prevention plan (discussed later in this document) in place that will 
help avoid the occurrence of a spill and the impacts to the environment 
(including marine mammals) should one occur.
    BP's activities at Northstar will also introduce sound into the 
environment. The potential effects of sound from the proposed 
activities might include one or more of the following: Masking of 
natural sounds; behavioral disturbance and associated habituation 
effects; and, at least in theory, temporary or permanent hearing 
impairment. Because of the low source levels for the majority of 
equipment used at Northstar, no hearing impairment is expected in any 
pinnipeds or cetaceans. Other types of effects are expected to be less 
for cetaceans, as the higher sound levels are found close to shore, 
usually further inshore than the migration paths of cetaceans. 
Additionally, cetaceans are not found in the Northstar area during the 
ice-covered season; therefore, they would only be potentially impacted 
during certain times of the year. As discussed earlier in the document, 
cetaceans often avoid sound sources, which would further reduce impacts 
from sound. Pinnipeds may exhibit some behavioral disturbance 
reactions, but they are anticipated to be minor. In summary, impacts to 
marine mammals that may occur in the Northstar area are expected to be 
minor, as source levels are low and many of the species are found 
farther out to sea.
    Moreover, the potential effects to marine mammals described in this 
section of the document do not take into consideration the proposed 
monitoring and mitigation measures described later in this document 
(see the ``Proposed Mitigation'' and ``Proposed Monitoring and 
Reporting'' sections).

Anticipated Effects on Habitat

    Potential impacts to marine mammals and their habitat as a result 
of operation of the Northstar facility are mainly associated with 
elevated sound levels. However, potential impacts are also possible 
from ice road construction and an oil spill (should one occur).

Common Marine Mammal Prey in the Project Area

    All six of the marine mammal species that may occur in the proposed 
project area prey on either marine fish or invertebrates. The ringed 
seal feeds on fish and a variety of benthic species, including crabs 
and shrimp. Bearded seals feed mainly on benthic organisms, primarily 
crabs, shrimp, and clams. Spotted seals feed on pelagic and demersal 
fish, as well as shrimp and cephalopods. They are known to feed on a 
variety of fish including herring, capelin, sand lance, Arctic cod, 
saffron cod, and sculpins.
    Bowhead whales feed in the eastern Beaufort Sea during summer and 
early autumn, but continue feeding to varying degrees while on their 
migration through the central and western Beaufort Sea in the late 
summer and fall (Richardson and Thomson [eds.], 2002). Aerial surveys 
in recent years have sighted bowhead whales feeding in Camden Bay on 
their westward migration through the Beaufort Sea. [Camden Bay is more 
than 62 mi (100 km) east of Northstar.] When feeding in relatively 
shallow areas, bowheads feed throughout the water column. However, 
feeding is concentrated at depths where zooplankton is concentrated 
(Wursig et al., 1984, 1989; Richardson [ed.], 1987; Griffiths et al., 
2002). Lowry and Sheffield (2002) found that copepods and euphausiids 
were the most common prey found in stomach samples from bowhead whales 
harvested in the Kaktovik area from 1979 to 2000. Areas to the east of 
Barter Island (which is approximately 110 mi [177 km] east of 
Northstar) appear to be used regularly for feeding as bowhead whales 
migrate slowly westward across the Beaufort Sea (Thomson and 
Richardson, 1987; Richardson and Thomson [eds.], 2002). However, in 
some years, sizable groups of bowhead whales have been seen feeding as 
far west as the waters just east of Point Barrow (which is more than 
155 mi [250 km] west of Northstar) near the Plover Islands (Braham et 
al., 1984; Ljungblad et al., 1985; Landino et al., 1994). The situation 
in September-October 1997 was unusual in that bowheads fed widely 
across the Alaskan Beaufort Sea, including higher numbers in the area 
east of Barrow than reported in any previous year (S. Treacy and D. 
Hansen, MMS, pers. comm.).
    Beluga whales feed on a variety of fish, shrimp, squid and octopus 
(Burns and Seaman, 1985). Very few beluga whales occur near Northstar; 
their main migration route is much further offshore.
    Gray whales are primarily bottom feeders, and benthic amphipods and 
isopods form the majority of their summer diet, at least in the main 
summering areas west of Alaska (Oliver et al., 1983; Oliver and 
Slattery, 1985). Farther south, gray whales have also been observed 
feeding around kelp beds, presumably on mysid crustaceans, and on 
pelagic prey such as small schooling fish and crab larvae (Hatler and 
Darling, 1974).
    Two kinds of fish inhabit marine waters in the study area: (1) True 
marine fish that spend all of their lives in salt water, and (2) 
anadromous species that reproduce in fresh water and spend parts of 
their life cycles in salt water.
    Most arctic marine fish species are small, benthic forms that do 
not feed high in the water column. The majority of these species are 
circumpolar and are found in habitats ranging from deep offshore water 
to water as shallow as 16.4-33 ft (5-10 m; Fechhelm et al., 1995). The 
most important pelagic species, and the only abundant pelagic species, 
is the Arctic cod. The Arctic cod is a major vector for the transfer of 
energy from lower to higher trophic levels (Bradstreet et al., 1986). 
In summer, Arctic cod can form very large schools in both nearshore and 
offshore waters (Craig et al., 1982; Bradstreet et al., 1986). 
Locations and areas frequented by large schools of Arctic cod cannot be 
predicted, but can be almost anywhere. The Arctic cod is a major food 
source for beluga whales, ringed seals, and numerous species of 
seabirds (Frost and Lowry, 1984; Bradstreet et al., 1986).
    Anadromous Dolly Varden char and some species of whitefish winter 
in rivers and lakes, migrate to the sea in spring and summer, and 
return to fresh water in autumn. Anadromous fish form the basis of 
subsistence, commercial, and small regional sport fisheries. Dolly 
Varden char migrate to the sea from May through mid-June (Johnson, 
1980) and spend about 1.5 to 2.5 months there (Craig, 1989). They 
return to rivers beginning in late July or early August with the peak 
return migration occurring between mid-August and early September 
(Johnson, 1980). At sea, most anadromous corregonids (whitefish) remain 
in nearshore waters within several kilometers of shore (Craig, 1984, 
1989). They are often termed ``amphidromous'' fish in that they make 
repeated annual migrations into marine waters to feed, returning each 
fall to overwinter in fresh water.
    Benthic organisms are defined as bottom dwelling creatures. 
Infaunal organisms are benthic organisms that live within the substrate 
and are often sedentary or sessile (bivalves, polychaetes). Epibenthic 
organisms live on or near the bottom surface sediments and are mobile 
(amphipods, isopods, mysids, and some polychaetes). Epifauna, which 
live attached to hard substrates, are rare in the Beaufort Sea because 
hard substrates are scarce there. A small community of epifauna, the

[[Page 39727]]

Boulder Patch, occurs in Stefansson Sound.
    The benthic environment near Northstar appears similar to that 
reported in various other parts of the Arctic (Ellis, 1960, 1962, 1966; 
Dunbar, 1968; Wacasey, 1975). Many of the nearshore benthic marine 
invertebrates of the Arctic are circumpolar and are found over a wide 
range of water depths (Carey et al., 1975). Species identified include 
polychaetes (Spio filicornis, Chaetozone setosa, Eteone longa), 
bivalves (Cryrtodaria kurriana, Nucula tenuis, Liocyma fluctuosa), an 
isopod (Saduria entomon), and amphipods (Pontoporeia femorata, P. 
affinis).
    Nearshore benthic fauna have been studied in lagoons west of 
Northstar and near the mouth of the Colville River (Kinney et al., 
1971, 1972; Crane and Cooney, 1975). The waters of Simpson Lagoon, 
Harrison Bay, and the nearshore region support a number of infaunal 
species including crustaceans, mollusks, and polychaetes. In areas 
influenced by river discharge, seasonal changes in salinity can greatly 
influence the distribution and abundance of benthic organisms. Large 
fluctuations in salinity and temperature that occur over a very short 
time period, or on a seasonal basis, allow only very adaptable, 
opportunistic species to survive (Alexander et al., 1974). Since 
shorefast ice is present for many months, the distribution and 
abundance of most species depends on annual (or more frequent) 
recolonization from deeper offshore waters (Woodward Clyde Consultants, 
1995). Due to ice scouring, particularly in water depths of less than 8 
ft (2.4 m), infaunal communities tend to be patchily distributed. 
Diversity increases with water depth until the shear zone is reached at 
49-82 ft (15-25 m; Carey, 1978). Biodiversity then declines due to ice 
gouging between the landfast ice and the polar pack ice (Woodward Clyde 
Consultants, 1995).

Potential Impacts From Sound Generation

    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.
    Fishes produce sounds that are associated with behaviors that 
include territoriality, mate search, courtship, and aggression. It has 
also been speculated that sound production may provide the means for 
long distance communication and communication under poor underwater 
visibility conditions (Zelick et al., 1999), although the fact that 
fish communicate at low-frequency sound levels where the masking 
effects of ambient noise are naturally highest suggests that very long 
distance communication would rarely be possible. Fishes have evolved a 
diversity of sound generating organs and acoustic signals of various 
temporal and spectral contents. Fish sounds vary in structure, 
depending on the mechanism used to produce them (Hawkins, 1993). 
Generally, fish sounds are predominantly composed of low frequencies 
(less than 3 kHz).
    Since objects in the water scatter sound, fish are able to detect 
these objects through monitoring the ambient noise. Therefore, fish are 
probably able to detect prey, predators, conspecifics, and physical 
features by listening to environmental sounds (Hawkins, 1981). There 
are two sensory systems that enable fish to monitor the vibration-based 
information of their surroundings. The two sensory systems, the inner 
ear and the lateral line, constitute the acoustico-lateralis system.
    Although the hearing sensitivities of very few fish species have 
been studied to date, it is becoming obvious that the intra- and inter-
specific variability is considerable (Coombs, 1981). Nedwell et al. 
(2004) compiled and published available fish audiogram information. A 
noninvasive electrophysiological recording method known as auditory 
brainstem response is now commonly used in the production of fish 
audiograms (Yan, 2004). Generally, most fish have their best hearing in 
the low-frequency range (i.e., less than 1 kHz). Even though some fish 
are able to detect sounds in the ultrasonic frequency range, the 
thresholds at these higher frequencies tend to be considerably higher 
than those at the lower end of the auditory frequency range.
    Literature relating to the impacts of sound on marine fish species 
can be divided into the following categories: (1) Pathological effects; 
(2) physiological effects; and (3) behavioral effects. Pathological 
effects include lethal and sub-lethal physical damage to fish; 
physiological effects include primary and secondary stress responses; 
and behavioral effects include changes in exhibited behaviors of fish. 
Behavioral changes might be a direct reaction to a detected sound or a 
result of the anthropogenic sound masking natural sounds that the fish 
normally detect and to which they respond. The three types of effects 
are often interrelated in complex ways. For example, some physiological 
and behavioral effects could potentially lead to the ultimate 
pathological effect of mortality. Hastings and Popper (2005) reviewed 
what is known about the effects of sound on fishes and identified 
studies needed to address areas of uncertainty relative to measurement 
of sound and the responses of fishes. Popper et al. (2003/2004) also 
published a paper that reviews the effects of anthropogenic sound on 
the behavior and physiology of fishes.
    The following discussions of the three primary types of potential 
effects on fish from exposure to sound mostly consider continuous sound 
sources since the majority of sounds that will be generated by the 
proposed activities associated with Northstar are of a continuous 
nature; however, most research reported in the literature focuses on 
the effects of airguns, which produce pulsed sounds.
    Potential effects of exposure to continuous sound on marine fish 
include TTS, physical damage to the ear region, physiological stress 
responses, and behavioral responses such as startle response, alarm 
response, avoidance, and perhaps lack of response due to masking of 
acoustic cues. Most of these effects appear to be either temporary or 
intermittent and therefore probably do not significantly impact the 
fish at a population level. The studies that resulted in physical 
damage to the fish ears used noise exposure levels and durations that 
were far more extreme than would be encountered under conditions 
similar to those expected at Northstar.
    The situation for disturbance responses is less clear. Fish do 
react to underwater noise from vessels and move out of the way, move to 
deeper depths, or change their schooling behavior. The received levels 
at which fish react are not known and in fact are somewhat variable 
depending upon circumstances and species. In order to assess the 
possible effects of underwater project noise, it is best to examine 
project noise in relation to continuous noises routinely produced by 
other projects and activities such as shipping, fishing, etc.
    Construction activities at Northstar produced both impulsive sounds 
(e.g., pile driving) and longer-duration sounds. Short, sharp sounds 
can cause overt or subtle changes in fish behavior. Chapman and Hawkins 
(1969) tested the reactions of whiting (hake) in the field to an 
airgun. When the airgun was fired, the fish dove from 82 to 180 ft (25 
to 55 m) depth and formed a compact layer.

[[Page 39728]]

The whiting dove when received sound levels were higher than 178 dB re 
1 [micro]Pa (Pearson et al., 1992).
    Pearson et al. (1992) conducted a controlled experiment to 
determine effects of strong noise pulses on several species of rockfish 
off the California coast. They used an airgun with a source level of 
223 dB re 1 [micro]Pa. They noted:
     Startle responses at received levels of 200-205 dB re 1 
[micro]Pa and above for two sensitive species, but not for two other 
species exposed to levels up to 207 dB;
     Alarm responses at 177-180 dB for the two sensitive 
species, and at 186 to 199 dB for other species;
     An overall threshold for the above behavioral response at 
about 180 dB;
     An extrapolated threshold of about 161 dB for subtle 
changes in the behavior of rockfish; and
     A return to pre-exposure behaviors within the 20-60 minute 
exposure period.
    In summary, fish often react to sounds, especially strong and/or 
intermittent sounds of low frequency. Sound pulses at received levels 
of 160 dB re 1 [micro]Pa may cause subtle changes in behavior. Pulses 
at levels of 180 dB may cause noticeable changes in behavior (Chapman 
and Hawkins, 1969; Pearson et al., 1992; Skalski et al., 1992). It also 
appears that fish often habituate to repeated strong sounds rather 
rapidly, on time scales of minutes to an hour. However, the habituation 
does not endure, and resumption of the strong sound source may again 
elicit disturbance responses from the same fish. Underwater sound 
levels from Northstar, even during construction, were lower than the 
response threshold reported by Pearson et al. (1992), and are not 
likely to result in major effects to fish near Northstar.
    The reactions of fish to research vessel sounds have been measured 
in the field with forward-looking echosounders. Sound produced by a 
ship varies with aspect and is lowest directly ahead of the ship and 
highest within butterfly-shaped lobes to the side of the ship (Misund 
et al., 1996). Because of this directivity, fish that react to ship 
sounds by swimming in the same direction as the ship may be guided 
ahead of it (Misund, 1997). Fish in front of a ship that show avoidance 
reactions may do so at ranges of 164 to 1,148 ft (50 to 350 m; Misund, 
1997), though reactions probably will depend on the species of fish. In 
some instances, fish will likely avoid the ship by swimming away from 
the path and become relatively concentrated to the side of the ship 
(Misund, 1997). Most schools of fish are likely to show avoidance if 
they are not in the path of the vessel. When the vessel passes over 
fish, some species, in some cases, show sudden escape responses that 
include lateral avoidance and/or downward compression of the school 
(Misund, 1997). Some fish show no reaction. Avoidance reactions are 
quite variable and depend on species, life history stage, behavior, 
time of day, whether the fish have fed, and sound propagation 
characteristics of the water (Misund, 1997).
    Some of the fish species found in the Arctic are prey sources for 
odontocetes and pinnipeds. A reaction by fish to sounds produced by the 
operations at Northstar would only be relevant to marine mammals if it 
caused concentrations of fish to vacate the area. Pressure changes of 
sufficient magnitude to cause that type of reaction would probably 
occur only very close to the sound source, if any would occur at all 
due to the low energy sounds produced by the majority of equipment at 
Northstar. Impacts on fish behavior are predicted to be 
inconsequential. Thus, feeding odontocetes and pinnipeds would not be 
adversely affected by this minimal loss or scattering, if any, of 
reduced prey abundance.
    Reactions of zooplankton to sound are, for the most part, not 
known. Their ability to move significant distances is limited or nil, 
depending on the type of zooplankton. Behavior of zooplankters is not 
expected to be affected by drilling and production operations at 
Northstar. These animals have exoskeletons and no air bladders. Many 
crustaceans can make sounds, and some crustacea and other invertebrates 
have some type of sound receptor. 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 sounds produced by the operations at 
Northstar 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 
sound source, if any would occur at all due to the low energy sounds 
produced by the majority of equipment at Northstar. Impacts on 
zooplankton behavior are predicted to be inconsequential. Thus, feeding 
mysticetes would not be adversely affected by this minimal loss or 
scattering, if any, of reduced zooplankton abundance.

Potential Impacts From Ice Road Construction

    Ringed seals dig lairs in the sea ice near and around Northstar 
during the pupping season. There is the potential for ice road 
construction to impact areas of the ice used by ringed seals to create 
these lairs and breathing holes. Ice habitat for ringed seal breathing 
holes and lairs (especially for mothers and pups) is normally 
associated with pressure ridges or cracks (Smith and Stirling, 1975). 
The amount of habitat altered by Northstar ice road construction is 
minimal compared to the overall habitat available in the region. 
Densities of ringed seals on the ice near Northstar during late spring 
are similar to densities seen elsewhere in the region (Miller et al., 
1998b; Link et al., 1999; Moulton et al., 2002, 2005). Ringed seals use 
multiple breathing holes (Smith and Stirling, 1975; Kelly and 
Quakenbush, 1990) and are not expected to be adversely affected by the 
loss of one to two breathing holes within the thickened ice road. 
Ringed seals near Northstar appear to have the ability to open new 
holes and create new structures throughout the winter, and ringed seal 
use of landfast ice near Northstar did not appear to be much different 
than that of ice 1.2-2.2 mi away (2-3.5 km; Williams et al., 2002). 
Active seal structures were found within tens of meters of thickened 
ice (Williams et al., 2006b,c). A few ringed seals occur within areas 
of artificially thickened ice if cracks that can be exploited by seals 
form in that thickened ice. Therefore, ice road construction activities 
are not anticipated to have a major impact on the availability of ice 
for lairs and breathing holes for ringed seals in the vicinity of 
Northstar.

Potential Impacts From an Oil Spill

    Oil spill probabilities for the Northstar project have been 
calculated based on historic oil spill data. Probabilities vary 
depending on assumptions and method of calculation. A reanalysis of 
worldwide oil spill data indicates the probability of a large oil spill 
(>1,000 barrels) during the lifetime of Northstar is low (S.L. Ross 
Environmental Research Ltd., 1998). That report uses standardized units 
such as well-years and pipeline mile-years to develop oil spill 
probabilities for the Northstar project. Well-years represent the 
summed number of years that the various wells will be producing, and 
mile-years represent the length of pipeline times the amount of time 
the

[[Page 39729]]

pipeline is in service. The calculated probability of a large oil spill 
takes into account the state-of-the-art engineering and procedures used 
at Northstar. That probability is far lower than previously-estimated 
probabilities (23-26%), which were based on Minerals Management Service 
(MMS, now the Bureau of Ocean Energy Management [BOEM]), studies of 
offshore oil field experience in the Gulf of Mexico and California 
(USACE, 1998a).
    Based on the MMS exposure variable and an estimated production of 
158 million barrels of oil, the probability of one or more well 
blowouts or tank spills >1,000 barrels on Seal Island is 7% throughout 
the life of the project (approximately 15-20 years; USACE, 1998a). The 
chance of the maximum estimated well blowout volume (225,000 barrels) 
being released is very low. Tank spills would likely be contained to 
the island itself. Based on the MMS exposure variable, there is an 
estimated 19% probability of one or more offshore pipeline ruptures or 
leaks releasing 1,000 barrels or more. However, of the 12 pipeline 
spills in OCS areas of >1,000 barrels from 1964-1992, anchor damage to 
the pipeline caused 7 spills, hurricane damage caused 2, trawl damage 
caused 2, and pipeline corrosion caused 1. The Northstar pipeline is 
buried, and there is minimal boat traffic in the area, therefore 
eliminating damage from anchors or trawls. With these two events 
eliminated, the risk of an offshore pipeline spill is reduced to 5%. A 
second exposure variable, based on the CONCAWE exposure variable (which 
is a European organization that maintains a database relevant to 
environment, health, and safety activities associated with the oil 
industry), indicates there is a 1.6 to 2.4% probability for one or more 
offshore pipeline ruptures or leaks releasing >1,000 barrels (USACE, 
1998a). It should also be noted that production at BP's Northstar 
facility has declined significantly since it originally began operating 
nearly 10 years ago. The oil spill assessment conducted in the late 
1990s was based on original peak production levels (which was 
approximately 80,000 barrels/day), not current production levels (which 
is approximately 18,000 barrels/day; B. Streever, BP Senior 
Environmental Studies Advisor, 2011, pers. comm.).
    In the unlikely event of an oil spill from the Northstar pipeline, 
flow through the line can be stopped. There are automated isolation 
valves at each terminus of pipeline and at the mainland landfall, 
including along the sales line at Northstar Island, where the pipeline 
comes onshore, and at Pump Station 1. These would allow isolation of 
the marine portion of the line at the island and at the shore landing 
south of the island.
    The Northstar pipe wall thickness is approximately 2.8 x greater 
than that required to contain the maximum operating gas pressure. 
Therefore, the probability of a gas pipeline leak is considered to be 
low. Also, a gas pipeline leak is not considered to be a potential 
source of an oil spill.
(1) Oil Effects on Seal and Whale Prey
    Arctic cod and other fishes are a principal food item for beluga 
whales and seals in the Beaufort Sea. Anadromous fish are more 
sensitive to oil when in the marine environment than when in the fresh 
water environment (Moles et al., 1979). Generally, arctic fish are more 
sensitive to oil than are temperate species (Rice et al., 1983). 
However, fish in the open sea are unlikely to be affected by an oil 
spill. Fish in shallow nearshore waters could sustain heavy mortality 
if an oil slick were to remain in the area for several days or longer. 
Fish concentrations in shallow nearshore areas that are used as feeding 
habitat for seals and whales could be unavailable as prey. Because the 
animals are mobile, effects would be minor during the ice-free period 
when whales and seals could go to unaffected areas to feed.
    Effects of oil on zooplankton as food for bowhead whales were 
discussed by Richardson ([ed.] 1987). Zooplankton populations in the 
open sea are unlikely to be depleted by the effects of an oil spill. 
Oil concentrations in water under a slick are low and unlikely to have 
anything but very minor effects on zooplankton. Zooplankton populations 
in near surface waters could be depleted; however, concentrations of 
zooplankton in near-surface waters generally are low compared to those 
in deeper water (Bradstreet et al., 1987; Griffiths et al., 2002).
    Some bowheads feed in shallow nearshore waters (Bradstreet et al., 
1987; Richardson and Thomson [eds.], 2002). Wave action in nearshore 
waters could cause high concentrations of oil to be found throughout 
the water column. Oil slicks in nearshore feeding areas could 
contaminate food and render the site unusable as a feeding area. 
However, bowhead feeding is uncommon along the coast near the Northstar 
Development area, and contamination of certain areas would have only a 
minor impact on bowhead feeding. In the Beaufort Sea, Camden Bay and 
Point Barrow are more common feeding grounds for bowhead whales. 
Additionally, gray whales do not commonly feed in the Beaufort Sea and 
are rarely seen near the Northstar Development area.
    Effects of oil spills on zooplankton as food for seals would be 
similar to those described above for bowhead whales. Effects would be 
restricted to nearshore waters. During the ice-free period, effects on 
seal feeding would be minor.
    Bearded seals consume benthic animals. Wave action in nearshore 
waters could cause oil to reach the bottom through adherence to 
suspended sediments (Sanders et al., 1990). There could be mortality of 
benthic animals and elimination of some benthic feeding habitat. During 
the ice-free period, effects on seal feeding would be minor.
    Effects on availability of feeding habitat would be restricted to 
shallow nearshore waters. During the ice-free period, seals and whales 
could find alternate feeding habitats.
    The ringed seal is the only marine mammal present near Northstar in 
significant numbers during the winter. An oil spill in shallow waters 
could affect habitat availability for ringed seals during winter. The 
oil could kill ringed seal food and/or drive away mobile species such 
as the arctic cod. Effects of an oil spill on food supply and habitat 
would be locally significant for ringed seals in shallow nearshore 
waters in the immediate vicinity of the spill and oil slick in winter. 
Effects of an oil spill on marine mammal foods and habitat under other 
circumstances are expected to be minor.
(2) Oil Effects on Habitat Availability
    The subtidal marine plants and animals associated with the Boulder 
Patch community of Stefansson Sound are not likely to be affected 
directly by an oil spill from Northstar Island, seaward of the barrier 
islands and farther west. The only type of oil that could reach the 
subtidal organisms (located in 16 to 33 ft [5 to 10 m] of water) would 
be highly dispersed oil created by heavy wave action and vertical 
mixing. Such oil has no measurable toxicity (MMS, 1996). The amount and 
toxicity of oil reaching the subtidal marine community is expected to 
be so low as to have no measurable effect. However, oil spilled under 
the ice during winter, if it reached the relevant habitat, could act to 
reduce the amount of light available to the kelp species and other 
organisms directly beneath the spill. This could be an indirect effect 
of a spill. Due to the highly variable winter lighting conditions, any 
reduction in light penetration resulting from an oil spill would not be 
expected to have a

[[Page 39730]]

significant impact on the growth of the kelp communities.
    Depending on the timing of a spill, planktonic larval forms of 
organisms in arctic kelp communities such as annelids, mollusks, and 
crustaceans may be affected by floating oil. The contact may occur 
anywhere near the surface of the water column (MMS, 1996). Due to their 
wide distribution, large numbers, and rapid rate of regeneration, the 
recovery of marine invertebrate populations is expected to occur soon 
after the surface oil passes. Spill response activities are not likely 
to disturb the prey items of whales or seals sufficiently to cause more 
than minor effects. Additionally, the likelihood of an oil spill is 
expected to be very low.
    In conclusion, NMFS has preliminarily determined that BP's proposed 
operation of the Northstar Development area is not expected to have any 
habitat-related effects that could cause significant or long-term 
consequences for individual marine mammals or on the food sources that 
they utilize.

Proposed Mitigation

    In order to issue an incidental take authorization (ITA) under 
section 101(a)(5)(A) of the MMPA, NMFS must, where applicable, 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 subsistence 
uses (where relevant).
    As part of its application, BP proposed several mitigation measures 
in order to ensure the least practicable adverse impact on marine 
mammal species that may occur in the proposed project area. BP proposed 
different mitigation measures for the ice-covered season and for the 
open-water season. The proposed mitigation measures are described fully 
in BP's application (see ADDRESSES) and summarized here.

Ice-Covered Season Proposed Mitigation Measures

    In order to reduce impacts to ringed seal construction of birth 
lairs, BP must begin winter construction activities (e.g., ice road 
construction) on the sea ice as early as possible once weather and ice 
conditions permit such activities. Any ice road or other construction 
activities that are initiated after March 1 in previously undisturbed 
areas in waters deeper than 10 ft (3 m) must be surveyed, using trained 
dogs, in order to identify and avoid ringed seal structures by a 
minimum of 492 ft (150 m). If dog surveys are conducted, trained dogs 
shall search all floating sea ice for any ringed seal structures. Those 
surveys shall be done prior to the new proposed activity on the 
floating sea ice to provide information needed to prevent injury or 
mortality of young seals. Additionally, after March 1 of each year, 
activities should avoid, to the greatest extent practicable, 
disturbance of any located seal structure. It should be noted that 
since 2001, none of BP's activities took place after March 1 in 
previously undisturbed areas during late winter, so no on-ice searches 
were conducted.

Open-Water Season Proposed Mitigation Measures

    All non-essential boat, hovercraft, barge, and air traffic shall be 
scheduled to avoid periods when whales (especially bowhead whales) are 
migrating through the area. Helicopter flights to support Northstar 
activities shall be limited to a corridor from Seal Island to the 
mainland, and, except when limited by weather or personnel safety, 
shall maintain a minimum altitude of 1,000 ft (305 m), except during 
takeoff and landing.
    Impact hammering activities may occur at any time of year to repair 
sheet pile or dock damage due to ice impingement. Impact hammering is 
most likely to occur during the ice-covered season or break-up period 
and would not be scheduled during the fall bowhead migration. However, 
if such activities were to occur during the open-water or broken ice 
season, certain mitigation measures that are described here are 
proposed to be required of BP. Based on studies by Blackwell et al. 
(2004a), it is predicted that only impact driving of sheet piles or 
pipes that are in the water (i.e., those on the dock) could produce 
received levels of 190 dB re 1 [mu]Pa (rms) and then only in immediate 
proximity to the pile. The impact pipe driving in June and July 2000 
did not produce received levels as high as 180 dB re 1 [mu]Pa (rms) at 
any location in the water. This was attributable to attenuation by the 
gravel and sheet pile walls (Blackwell et al., 2004a). BP anticipates 
that received levels for any pile driving that might occur within the 
sheet pile walls of the island in the future would also be less than 
180 dB (rms) at all locations in the water around the island. If impact 
pile driving were planned in areas outside the sheet pile walls, it is 
possible that received levels underwater might exceed the 180 dB re 1 
[mu]Pa (rms) level.
    NMFS has established acoustic thresholds that identify the received 
sound levels above which hearing impairment or other injury could 
potentially occur, which are 180 and 190 dB re 1 [mu]Pa (rms) for 
cetaceans and pinnipeds, respectively (NMFS, 1995, 2000). The 
established 180- and 190-dB re 1 [mu]Pa (rms) criteria are the received 
levels above which, in the view of a panel of bioacoustics specialists 
convened by NMFS before additional TTS measurements for marine mammals 
became available, one could not be certain that there would be no 
injurious effects, auditory or otherwise, to marine mammals. To prevent 
or at least minimize exposure to sound levels that might cause hearing 
impairment, a safety zone shall be established and monitored for the 
presence of seals and whales. Establishment of the safety zone of any 
source predicted to result in received levels underwater above 180 dB 
(rms) will be analyzed using existing data collected in the waters of 
the Northstar facility (see the ``Proposed Monitoring and Reporting'' 
section later in this document or BP's application).
    If observations and mitigation are required, a protected species 
observer stationed at an appropriate viewing location on the island 
will conduct watches commencing 30 minutes prior to the onset of impact 
hammering or other identified activity. The ``Proposed Monitoring and 
Reporting'' section later in this document contains a description of 
the observer program. If pinnipeds are seen within the 190 dB re 1 
[mu]Pa radius (the ``safety zone''), then operations shall shut down or 
reduce SPLs sufficiently to ensure that received SPLs do not exceed 
those prescribed here. If whales are observed within the 180 dB re 1 
[mu]Pa (rms) radius, operations shall shut down or reduce SPLs 
sufficiently to ensure that received SPLs do not exceed those 
prescribed here. The shutdown or reduced SPL shall be maintained until 
such time as the observed marine mammal(s) has been seen to have left 
the applicable safety zone or until 15 minutes have elapsed in the case 
of a pinniped or odontocete or 30 minutes in the case of a mysticete 
without resighting, whichever occurs sooner.
    Should any new drilling into oil-bearing strata be required during 
the effective period of these regulations, the drilling shall not take 
place during either open-water or spring-time broken ice conditions.

Oil Spill Contingency Plan

    The taking by harassment, injury, or mortality of any marine mammal 
species incidental to an oil spill is

[[Page 39731]]

prohibited. However, in the unlikely event of an oil spill, BP expects 
to be able to contain oil through its oil spill response and cleanup 
protocols. An oil spill prevention and contingency response plan was 
developed and approved by the Alaska Department of Environmental 
Conservation, U.S. Department of Transportation, U.S. Coast Guard, and 
BOEM (formerly MMS). The plan has been amended several times since its 
initial approval, with the last revision occurring in July 2010. Major 
changes since 1999 include the following: seasonal drilling 
restrictions from June 1 to July 20 and from October 1 until ice 
becomes 18 in (46 cm) thick; changes to the response planning standard 
for a well blowout as a result of reductions in well production rates; 
and deletion of ice auguring for monitoring potential sub-sea oil 
pipeline leaks during winter following demonstration of the LEOS leak 
detection system. Future changes to the response planning standards may 
be expected in response to declines in well production rates and 
pipeline throughput. The full plan can be viewed on the Internet at: 
http://www.nmfs.noaa.gov/pr/permits/incidental.htm.
    The plan consists of five parts. A short summary of the information 
contained in each part of the plan follows next. For more details, 
please refer to the plan itself.
    Part 1 contains the Response Action Plan, which provides initial 
emergency response actions and oil spill response scenarios. The 
Response Action Plan lays out who is to be notified in the case of a 
spill and how many people need to be on hand and for how long depending 
on the size and type of spill. It also outlines different deployment 
strategies, which include the use of vessels, helicopters, fixed-wing 
aircraft, vehicles, heavy all-terrain vehicles, and air boats, and 
during which seasons these strategies could be used. Several response 
scenarios and strategies were developed in accordance with the Alaska 
Administrative Code (AAC). They describe equipment, personnel, and 
strategies that could be used to respond to an oil spill. It should be 
noted that the scenarios are for illustration only and assume 
conditions only for the purposes of describing general procedures, 
strategies, tactics, and selected operational capabilities. This part 
of the plan discusses oil spill scenarios and response strategies, 
including: An oil storage tank rupture; a well blowout under typical 
summer conditions; a well blowout under typical winter conditions; a 
crude oil transmission pipeline release; a well blowout during typical 
spring conditions; a crude oil transmission pipeline rupture during 
spring break-up; a crude oil transmission pipeline rupture during 
summer; a crude oil transmission pipeline rupture during fall; and a 
crude oil transmission pipeline rupture during winter.
    Part 2 contains the Prevention Plan, which describes prevention 
measures to be implemented by facility personnel and inspection and 
maintenance programs. Personnel who handle oil equipment receive 
training in general North Slope work procedures, spill prevention, 
environmental protection awareness, safety, and site-specific 
orientation. Personnel also receive training in oil spill notification, 
oil spill source control, and hazardous waste operations and emergency 
response safety. This section of the plan also outlines fuel transfer 
procedures, leak detection, monitoring, and operating requirements for 
crude oil transmission pipelines, and management of oil storage tanks, 
including inspections and protection devices. This section also 
discusses the possibilities of corrosion and the monitoring that is 
conducted to manage the corrosion control programs. This section of the 
plan also contains a table outlining different types, causes, and sizes 
of spills and the actions that are taken and in place to prevent such 
potential discharges. Another table in this section outlines the types 
of inspections that occur on daily, weekly, monthly, and annual 
schedules at Northstar to ensure the equipment is still functioning 
properly and that leaks are not occurring.
    Part 3 of the plan contains Supplemental Information. Part 3 
provides background information on the facility, including descriptions 
of the facility, the receiving environment for potential spills, the 
incident command system, maximum response operating limitations, 
response resources (personnel and equipment), response training and 
drills, and protection of environmentally sensitive areas. The 
receiving environments include oil in open-water, in water and ice 
during the break-up or freeze-up periods, and on ice. In conditions up 
to approximately 30% ice, the trajectory of spilled oil would be based 
on the winds and currents at Northstar. Assuming a 10-knot wind from 
the northeast, oil spilled at Northstar could reach the barrier island 
shore of Long Island and if not contained, oil moving inland through 
the barrier island cuts could reach the Kuparuk River Delta. Oil 
trapped under a floating solid ice cover would rise and gather in pools 
or lenses at the bottom of the ice sheet and may become trapped or 
entrained as new ice grows beneath the oil. Based on the very slow 
moving currents under the ice near Northstar, oil is unlikely to spread 
beyond the initial point of contact. During freeze-up, the oil will 
most likely be entrained in the solidifying grease ice and slush 
present on the water surface prior to forming an ice sheet. Storm winds 
at this time often break up and disperse the newly forming ice, leaving 
the oil to spread temporarily in an open water condition until it 
becomes incorporated in the next freezing cycle. At break-up, ice 
concentrations are highly variable from hour to hour and over short 
distances. In high ice concentrations, oil spreading is reduced and the 
oil is partially contained by the ice. As the ice cover loosens, more 
oil could escape into larger openings as the floes move apart. 
Eventually, as the ice concentration decreases, the oil on the water 
surface behaves essentially as an open water spill, with localized 
patches being temporarily trapped by wind against individual floes. Oil 
present on the surface of individual floes will move with the ice as it 
responds to winds and nearshore currents. The spreading of oil on ice 
is similar to spreading of oil on land or snow. The rate is controlled 
by the density and viscosity of the oil, and the final contaminated 
area is dictated by the surface roughness of the ice. As the ice 
becomes rougher, the oil pools get smaller and thicker. Oil spilled on 
ice spreads much more slowly than on water and covers a smaller final 
area. As a result, slicks on stable solid ice tend to be much thicker 
than equivalent slicks on water. The effective containment provided by 
even a minimal degree of ice roughness (inches) translates to far less 
cleanup time with the need for fewer resources than would be needed to 
deal with the equivalent spill on open water. In the Supplemental 
Information section of the plan, a description of the different 
environments (e.g., open-water, freeze-up, etc.) is provided, including 
when those conditions occur and the types of ice thickness that are 
typical during each season.
    The command system, which is described in Part 3, is compatible 
with the Alaska Regional Response Team Unified Plan and is based on the 
National Incident Management System. According to the plan, oil spill 
removal during the freeze-up or break-up seasons can be greatly 
enhanced by in situ burning. The ice provides containment, increasing 
the encounter rate and concentrating the oil for burning and recovery. 
The consensus of research on

[[Page 39732]]

spill response in broken ice conditions is that in situ burning is an 
effective response technique, with removal rates exceeding 85 percent 
in many situations (Shell et al., 1983; SL Ross, 1983; SL Ross and DF 
Dickins, 1987; Singsaas et al., 1994). A considerable amount of 
research has demonstrated in situ burning in broken ice. The research 
includes several smaller-scale field and tank tests (SL Ross et al., 
2003; Shell et al., 1983; Brown and Goodman, 1986; Buist and Dickins, 
1987; Smith and Diaz, 1987; Bech et al., 1993; Gu[eacute]nette and 
Wighus, 1996) and one large field test (Singsaas et al., 1994). Most of 
the tests involved large volumes of oil placed in a static test field 
of broken ice, resulting in substantial slick thicknesses for ignition. 
The few tests in unrestricted ice fields or in dynamic ice have 
indicated that the efficacy of in situ burning is sensitive to ice 
concentration and dynamics and thus the tendency for the ice floes to 
naturally contain the oil, the thickness (or coverage) of oil in leads 
between floes, and the presence or absence of brash (created when 
larger ice features interact or degrade) or frazil (``soupy'' mixture 
of very small ice particles that form as seawater freezes) ice which 
can absorb the oil. Oil spilled on solid ice or among broken ice in 
concentrations equal to or greater than 6-tenths has a high probability 
of becoming naturally contained in thicknesses sufficient for 
combustion. Field experience has shown that it is the small ice pieces 
(e.g., the brash and frazil, or slush, ice) that accumulate with the 
oil against the edges of larger ice features (floes) and control the 
concentration (e.g., thickness) of oil in an area, and control the rate 
at which the oil subsequently thins and spreads. The plan contains a 
summary discussion on the current state of understanding the scientific 
principles and physical processes involved for in situ burning of oil 
on melt pools during the ice melt phase in June or on water between 
floes during the break-up period in July, based on SL Ross et al. 
(2003). Further discussion also covers in situ burning of thinner 
slicks in mobile broken ice comprised of brash or frazil ice during the 
freeze-up shoulder season in October. Please refer to the plan for 
these discussions.
    Part 4 discusses Best Available Technology (BAT). This section 
provides a rationale for the prevention technology in place at the 
facility and a determination of whether or not it is the best available 
technology. The plan identifies two methods for regaining well control 
once an incident has escalated to a surface blowout scenario as 
described in Part 1 of the plan. The two methods are: Well-capping and 
relief well drilling. BP investigations indicate that well-capping 
constitutes the BAT for source control of a blowout. Well-capping 
response operations are highly dependent on the severity of the well 
control situation. BP has the ability to move specialized personnel and 
equipment, e.g., capping stack or cutting tools, to North Slope 
locations upon declaration of a well control event. The materials to 
execute control (e.g., junk shots, hot tapping, freezing, or crimping), 
are small enough that they can be quickly made available to remote 
locations, even by aircraft, as necessary. BP has an inventory of well 
control firefighting equipment permanently warehoused on the North 
Slope. This equipment includes two 6,000 gallons per minute (gpm) fire 
pumps, associated piping, lighting, transfer pumps, Athey wagons, 
specialized nozzles, and fire monitor shacks. Maintaining this 
equipment on the North Slope minimizes the time to mobilize and 
transport well control response equipment in an actual blowout event. 
Relief well drilling technology is compatible to North Slope drilling 
operations although it may be sensitive to both the well location and 
well types; however, it can be a timely process. Onshore North Slope 
relief well durations are often estimated in the 40- to 90-day range. 
While BP has determined that well capping constitutes BAT for well 
source control, BP has deemed it prudent to also activate a separate 
team to pursue a relief well plan parallel to and independent of the 
primary well capping plan.
    The pipeline source control procedures, required by the AAC, 
involve the placement of automatic shutdown valves at each terminus and 
at the shore crossing to stop the flow of oil or product/gas into the 
Northstar pipelines. Additionally, the oil pipeline across the 
Putuligayuk River includes a manual valve on both sides of the river. 
There are two technology options for the valves: Automatic ball valves 
and automatic gate valves. Both valve options, when installed in new 
condition, are similar in terms of availability, transferability, cost, 
compatibility, and feasibility. In terms of effectiveness, ball valves 
typically have slightly faster closure times than gate valves. For 
Northstar, automatic ball valves (block and bleed type) are used. As 
required by 18 AAC 75.055(b), the flow of oil or product/gas can be 
completely stopped by these valves within one hour after a discharge 
has been detected. The valve closure time for these types of valves is 
usually on the order of 2 to 3 minutes.
    Part 5 outlines the Response Planning Standard, which provides 
calculations of the applicable response planning standards for 
Northstar, including a detailed basis for the calculation reductions to 
be applied to the response planning standards.

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 adverse 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;
     The proven or likely efficacy of the specific measure to 
minimize adverse impacts as planned; and
     The practicability of the measure for applicant 
implementation.
    Based on our evaluation of the applicant's proposed measures, NMFS 
has preliminarily determined that the mitigation measures proposed 
above provide the means of effecting the least practicable adverse 
impact on marine mammal species or stocks and their habitat, paying 
particular attention to rookeries, mating grounds, and areas of similar 
significance. Proposed measures to ensure availability of such species 
or stock for taking for certain subsistence uses is discussed later in 
this document (see ``Impact on Availability of Affected Species or 
Stock for Taking for Subsistence Uses'' section).
    The proposed rule comment period will afford the public an 
opportunity to submit recommendations, views, and/or concerns regarding 
this action and the proposed mitigation measures. While NMFS has 
determined preliminarily that the proposed mitigation measures 
presented in this document will effect the least practicable adverse 
impact on the affected species or stocks and their habitat, NMFS will 
consider all public comments to help inform our final decision. 
Consequently, the proposed mitigation measures may be refined, 
modified, removed, or added to prior to the issuance of the final rule 
based on public comments received, and where appropriate, further 
analysis of any additional mitigation measures.

[[Page 39733]]

Proposed Monitoring and Reporting

    In order to issue an ITA for an activity, section 101(a)(5)(A) of 
the MMPA states that NMFS must, where applicable, 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.
    The monitoring program proposed by BP in its application and 
described here is based on the continuation of previous monitoring 
conducted at Northstar. Information on previous monitoring can be found 
in the ``Previous Activities and Monitoring'' section found later in 
this document. The proposed monitoring program may be modified or 
supplemented based on comments or new information received from the 
public during the public comment period or from the peer review panel 
(see the ``Monitoring Plan Peer Review'' section later in this 
document).
    The monitoring proposed by BP focuses on ringed seals and bowhead 
whales, as they are the most prevalent species found in the Northstar 
Development area. No monitoring is proposed specifically for bearded or 
spotted seals or for gray or beluga whales, as their occurrence near 
Northstar is limited. Few, if any, observations of these species were 
made during the intensive monitoring from 1999 to 2004. However, if 
sightings of these (or other) species are made, those observations will 
be included in the monitoring reports (described later in this 
document) that will be prepared.

Annual Monitoring Plans

    BP proposes to continue the long-term observer program, conducted 
by island personnel, of ringed seals during the spring and summer. This 
program is intended to assess the continued long-term stability of 
ringed seal abundance and habitat use near Northstar as indexed by 
counts obtained on a regular and long-term basis. The proposed approach 
is to continue the Northstar seal count that is conducted during the 
period May 15-July 15 each year from the 108 ft (33 m) high process 
module by Northstar staff following a standardized protocol since 2005. 
Counts are made on a daily basis (weather permitting), between 11:00-
19:00, in an area of approximately 3,117 ft (950 m) around the island, 
for a duration of approximately 15 minutes. Counts will only be made 
during periods with visibility of 0.62 mi (1 km) or more and with a 
cloud ceiling of more than 295 ft (90 m).
    BP proposes to continue monitoring the bowhead migration in 2011 
and subsequent years for approximately 30 days each September through 
the recording of bowhead calls. BP proposes to deploy a Directional 
Autonomous Seafloor Acoustic Recorder (DASAR; Greene et al., 2004) or 
similar recorder about 9.3 mi (15 km) north of Northstar, consistent 
with a location used in past years (as far as conditions allow). The 
data of the offshore recorder can provide information on the total 
number of calls detected, the temporal pattern of calling during the 
recording period, possibly the bearing to calls, and call types. These 
data can be compared with corresponding data from the same site in 
previous years. If substantially higher or lower numbers of calls are 
recorded than were recorded at that site in previous years, further 
analyses and additional monitoring will be considered in consultation 
with NMFS and North Slope Borough (NSB) representatives. A second 
DASAR, or similar recorder, will be deployed at the same location to 
provide a reasonable level of redundancy.
    In addition to the DASAR already mentioned, BP proposes to install 
an acoustic recorder about 1,476 ft (450 m) north of Northstar, in the 
same area where sounds have been recorded since 2001. This recorder 
will be installed for approximately 30 days each September, 
corresponding with the deployment of the offshore DASAR (or similar 
recorder). The near-island recorder will be used to record and quantify 
sound levels emanating from Northstar. If island sounds are found to be 
significantly stronger or more variable than in the past, and if it is 
expected that the stronger sounds will continue in subsequent years, 
then further consultation with NMFS and NSB representatives will occur 
to determine if more analyses or changes in monitoring strategy are 
appropriate. A second acoustic recorder will be deployed to provide a 
reasonable level of redundancy.

Contingency Monitoring Plans

    If BP needs to conduct an activity (i.e., pile driving) capable of 
producing pulsed underwater sound with levels >= 180 or >= 190 dB re 1 
[micro]Pa (rms) at locations where whales or seals could be exposed, BP 
proposes to monitor safety zones defined by those levels. [The safety 
zones were described in the ``Proposed Mitigation'' section earlier in 
this document.] One or more on-island observers, as necessary to scan 
the area of concern, will be stationed at location(s) providing an 
unobstructed view of the predicted safety zone. The observer(s) will 
scan the safety zone continuously for marine mammals for 30 minutes 
prior to the operation of the sound source. Observations will continue 
during all periods of operation. If whales and seals are detected 
within the (respective) 180 or 190 dB distances, a shutdown or other 
appropriate mitigation measure (as described earlier in this document) 
shall be implemented. The sound source will be allowed to operate again 
when the marine mammals are observed to leave the safety zone or until 
15 minutes have elapsed in the case of a pinniped or odontocete or 30 
minutes in the case of a mysticete without resighting, whichever occurs 
sooner. The observer will record the: (1) Species and numbers of marine 
mammals seen within the 180 or 190 dB zones; (2) bearing and distance 
of the marine mammals from the observation point; and (3) behavior of 
marine mammals and any indication of disturbance reactions to the 
monitored activity.
    If BP initiates significant on-ice activities (e.g., construction 
of new ice roads, trenching for pipeline repair, or projects of similar 
magnitude) in previously undisturbed areas after March 1, trained dogs, 
or a comparable method, will be used to search for seal structures. If 
such activities do occur after March 1, a follow-up assessment must be 
conducted in May of that year to determine the fate of all seal 
structures located during the March monitoring. This monitoring must be 
conducted by a qualified biological researcher approved in advance by 
NMFS after a review of the observer's qualifications.
    BP will conduct acoustic measurements to document sound levels, 
characteristics, and transmissions of airborne sounds with expected 
source levels of 90 dBA or greater created by on-ice activity at 
Northstar that have not been measured in previous years. In addition, 
BP will conduct acoustic measurements to document sound levels, 
characteristics, and transmissions of airborne sounds for sources on 
Northstar Island with expected received levels at the water's edge that 
exceed 90 dBA that have not been measured in previous years. These data 
will be collected in order to assist in the development of future 
monitoring and mitigation measures.

[[Page 39734]]

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 established an independent peer review panel to review BP's 
proposed monitoring plan associated with the MMPA application for these 
proposed regulations. The panel met in early March 2011. After 
completion of the peer review, NMFS will consider all recommendations 
made by the panel, incorporate appropriate changes into the monitoring 
requirements of the final rule and subsequent LOAs, and publish the 
panel's findings and recommendations in the final rule.

Reporting Measures

    An annual report on marine mammal monitoring and mitigation will be 
submitted to NMFS, Office of Protected Resources, and NMFS, Alaska 
Regional Office, on June 1 of each year. The first report will cover 
the period from the effective date of the LOA through October 31, 2011. 
Subsequent reports will cover activities from November 1 of one year 
through October 31 of the following year. Ending each annual report 
with October 31 coincides with the end of the fall bowhead whale 
migration westward through the Beaufort Sea.
    The annual reports will provide summaries of BP's Northstar 
activities. These summaries will include the following: (1) Dates and 
locations of ice-road construction; (2) on-ice activities; (3) vessel/
hovercraft operations; (4) oil spills; (5) emergency training; and (6) 
major repair or maintenance activities that might alter the ambient 
sounds in a way that might have detectable effects on marine mammals, 
principally ringed seals and bowhead whales. The annual reports will 
also provide details of ringed seal and bowhead whale monitoring, the 
monitoring of Northstar sound via the nearshore DASAR, descriptions of 
any observed reactions, and documentation concerning any apparent 
effects on accessibility of marine mammals to subsistence hunters.
    If specific mitigation and monitoring are required for activities 
on the sea ice initiated after March 1 (requiring searches with dogs 
for lairs), during the operation of strong sound sources (requiring 
visual observations and shutdown procedures), or for the use of new 
sound sources that have not previously been measured, then a 
preliminary summary of the activity, method of monitoring, and 
preliminary results will be submitted within 90 days after the 
cessation of that activity. The complete description of methods, 
results, and discussion will be submitted as part of the annual report.
    In addition to annual reports, BP proposes to submit a draft 
comprehensive report to NMFS, Office of Protected Resources, and NMFS, 
Alaska Regional Office, no later than 240 days prior to the expiration 
of these regulations. This comprehensive technical report will provide 
full documentation of methods, results, and interpretation of all 
monitoring during the first four and a quarter years of the LOA. Before 
acceptance by NMFS as a final comprehensive report, the draft 
comprehensive report will be subject to review and modification by NMFS 
scientists.
    Any observations concerning possible injuries, mortality, or an 
unusual marine mammal mortality event will be transmitted to NMFS, 
Office of Protected Resources, and the Alaska Stranding and 
Disentanglement Program, within 48 hours of the discovery. At a 
minimum, reported information should include: (1) The time, date, and 
location (latitude/longitude) of the animal(s); (2) the species 
identification or description of the animal(s); (3) the fate of the 
animal(s), if known; and (4) photographs or video footage of the animal 
(if equipment is available).

Adaptive Management

    The final regulations governing the take of marine mammals 
incidental to operation of the Northstar facility in the U.S. Beaufort 
Sea will contain an adaptive management component. In accordance with 
50 CFR 216.105(c), regulations for the proposed activity must be based 
on the best available information. As new information is developed, 
through monitoring, reporting, or research, the regulations may be 
modified, in whole or in part, after notice and opportunity for public 
review. The use of adaptive management will allow NMFS to consider new 
information from different sources to determine if mitigation or 
monitoring measures should be modified (including additions or 
deletions) if new data suggest that such modifications are appropriate 
for subsequent LOAs.
    The following are some of the possible sources of applicable data:
     Results from BP's monitoring from the previous year;
     Results from general marine mammal and sound research; or
     Any information which reveals that marine mammals may have 
been taken in a manner, extent or number not authorized by these 
regulations or subsequent LOAs.
    If, during the effective dates of the regulations, new information 
is presented from monitoring, reporting, or research, these regulations 
may be modified, in whole, or in part after notice and opportunity of 
public review, as allowed for in 50 CFR 216.105(c). In addition, LOAs 
shall be withdrawn or suspended if, after notice and opportunity for 
public comment, the Assistant Administrator finds, among other things, 
the regulations are not being substantially complied with or the taking 
allowed is having more than a negligible impact on the species or stock 
or an unmitigable adverse impact on the availability of marine mammal 
species or stocks for taking for subsistence uses, as allowed for in 50 
CFR 216.106(e). That is, should substantial changes in marine mammal 
populations in the project area occur or monitoring and reporting show 
that operation of the Northstar facility is having more than a 
negligible impact on marine mammals or an unmitigable adverse impact on 
the availability of marine mammal species or stocks for taking for 
subsistence uses, then NMFS reserves the right to modify the 
regulations and/or withdraw or suspend a LOA after public review.

Previous Activities and Monitoring

    The ``Background on the Northstar Development Facility'' section 
earlier in this document discussed activities that have occurred at 
Northstar since construction began in the winter of 1999/2000. 
Activities that occurred at Northstar under the current regulations 
(valid April 6, 2006, through April 6, 2011) include transportation 
(e.g., helicopter, hovercraft, tracked vehicles, and vessels), 
production activities (e.g., power generation, pipe driving, etc.), 
construction and maintenance activities, and monitoring programs.
    Under those regulations and annual LOAs, BP has been conducting 
marine mammal monitoring within the action area to satisfy monitoring 
requirements set forth in MMPA authorizations. The monitoring programs 
have focused mainly on bowhead whales and ringed seals, as they are the 
two most common

[[Page 39735]]

marine mammal species found in the Northstar Development area. 
Monitoring conducted by BP during this time period included: (1) 
Underwater and in-air noise measurements; (2) monitoring of ringed seal 
lairs; (3) monitoring of hauled out ringed seals in the spring and 
summer months; and (4) acoustic monitoring of the bowhead whale 
migration. Additionally, although it was not a requirement of the 
regulations or associated LOAs, BP has also incorporated work done by 
Michael Galginaitis. Since 2001, Galginaitis has observed and 
characterized the fall bowhead whale hunts at Cross Island.
    As required by the regulations and annual LOAs, BP has submitted 
annual reports, which describe the activities and monitoring that 
occurred at Northstar. BP also submitted a draft comprehensive report, 
covering the period 2005-2009. The comprehensive report concentrates on 
BP's Northstar activities and associated marine mammal and acoustic 
monitoring projects from 2005-2009. However, monitoring work prior to 
2004 is summarized in that report, and activities in 2010 at Northstar 
were described as well. The annual reports and draft comprehensive 
report (Richardson [ed.], 2010) are available on the Internet at: 
http://www.nmfs.noaa.gov/pr/permits/incidental.htm#applications. A 
summary of the monitoring can be found here and elsewhere in this 
document. This section summarizes some of the key objectives and 
findings; however, specific results and findings of some of the 
monitoring work that has been conducted at Northstar over the past 
decade are also described in sections throughout this document.
    Prior to the start of construction (1997-1999) and during the first 
few years of Northstar construction and operation (2000-2002), BP 
conducted aerial surveys to study the distribution and abundance of 
seals around Northstar. In addition to aerial surveys, specially-
trained dogs were also used to locate seal lairs during the ice-covered 
seasons of 1999-2000 and 2000-2001. It was determined that such 
intensive monitoring was not required after 2002; however, BP continued 
to observe and count seals near Northstar in order to determine if 
seals continued to use the area, and, if so, if that usage was similar 
to that found in previous years. The current monitoring consists of 
someone making counts from a platform between May 15 and July 15 each 
year, although there is some variation in the number of days 
observations are made during that period from year-to-year. Counts 
ranged from a low of three seals counted during 57 observation days in 
2007 to a high of 811 seals counted during 61 observation days in 2009 
(Richardson [ed.], 2010). Based on the counts that have been conducted, 
ringed seals continue to haul out around Northstar.
    The LOAs also contained requirements to conduct underwater 
measurements of sounds produced by Northstar-related industrial 
activities. To obtain these measurements, BP deployed DASARs both near 
and offshore of Northstar. The exact distances and configurations are 
contained in Richardson [ed.] (2010). Median levels of sound were found 
to be low offshore of Northstar (95.4-103.1 dB re 1 [micro]Pa when 
measured 9.2 mi [14.9 km] away). Also, industrial sounds were found to 
contribute less of the sound in the 10-450 Hz band during 2005-2009 
than it did during the period of 2001-2004.
    Since 2001, BP has also been conducting acoustic monitoring to 
study the fall westward migration of bowhead whales through the 
Beaufort Sea and to determine whether or not sounds from Northstar are 
affecting that migration. The DASARs are also used for this monitoring 
effort. BP has studied the rate of calls per year and has also worked 
to localize the calls. Some of the key findings from this work showed 
that in 8 out of 9 seasons during the 2001-2009 period, bearings to 
whale calls detected at the same DASAR site 9.2 mi (14.9 km) offshore 
of Northstar were predominantly to the northeast or east-northeast of 
that location. Additionally, analysis of the 2008 data demonstrated 
that bowhead whale calls are directional, which may help to explain why 
fewer calls are detected west of Northstar than to the east (Richardson 
[ed.], 2010). In the comprehensive report (Richardson [ed.], 2010), BP 
compared calls from 2009 with those from 2001-2004 to try and draw 
conclusions about effects on the distribution of calling bowheads. BP 
found that from 2001-2004, the southern edge of the distribution of 
bowhead calls tended to be slightly but statistically significantly 
farther offshore when the underwater sound level near Northstar 
increased above baseline values. For the 2009 data, BP was unable to 
conclusively identify one specific relationship between offshore 
distances of bowhead calls and industrial sound.
    The annual reports and comprehensive report (Richardson [ed.], 
2010) also contain information on the fall Nuiqsut bowhead whale hunts. 
The information contained in these reports show that during 2005-2009, 
the whalers struck 3 or 4 whales (of a quota of 4) in all years except 
2005 (only one whale struck and landed). The whalers did not attribute 
the poor harvest in 2005 to activities at Northstar. That year, there 
was severe local ice and very poor weather. There was some vessel 
interference; however, none of that was with vessels at or conducting 
activities for Northstar. Sealing activities were not common near the 
Northstar site prior to its construction, and they are not common there 
now. Most sealing occurs more than 20 mi (32 km) from Northstar.
    During the period of validity of the current regulations, no 
activities have occurred after March 1 in previously undisturbed areas 
during late winter. Therefore, no monitoring with specially-trained 
dogs has been required. Also during this period, there were 82 
reportable small spills (such as 0.25 gallons of hydraulic fluid, 3 
gallons of power steering fluid, or other relatively small amounts of 
sewage, motor oil, hydraulic oil, sulfuric acid, etc.), three of which 
reached Beaufort water or ice. All material (for example, 0.03 gallons 
of hydraulic fluid) from these three spills was completely recovered.
    NMFS has determined that BP complied with the mitigation and 
monitoring requirements set forth in regulations and annual LOAs. In 
addition, NMFS has determined that the impacts on marine mammals and on 
the availability of marine mammals for subsistence uses from the 
activity fell within the nature and scope of those anticipated and 
authorized in the previous authorization (supporting the analysis in 
the current authorization).

Estimated Take of Marine Mammals

    One of the main purposes of NMFS' effects assessments is to 
identify the permissible methods of taking, which involves an 
assessment of the following criteria: the nature of the take (e.g., 
resulting from anthropogenic noise vs. from ice road construction, 
etc.); the regulatory level of take (i.e., mortality vs. Level A or 
Level B harassment); and the amount of take. In the ``Potential Effects 
of the Specified Activity on Marine Mammals'' section earlier in this 
document, NMFS identified the different types of effects that could 
potentially result from activities at BP's Northstar facility.
    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

[[Page 39736]]

patterns, including, but not limited to, migration, breathing, nursing, 
breeding, feeding, or sheltering [Level B harassment].'' Take by Level 
B harassment is anticipated from operational sounds extending into the 
open-water migration paths of cetaceans and open-water areas where 
pinnipeds might be present, from the physical presence of personnel on 
the island, vehicle traffic, and by helicopter overflights. Take of 
hauled out pinnipeds, by harassment, could also occur as a result of 
in-air sound sources. Certain species may have a behavioral reaction to 
the sound emitted during the activities; however, hearing impairment as 
a result of these activities is not anticipated because of the low 
source levels for much of the equipment that is used. There is also a 
potential for take by injury or mortality of ringed seals from ice road 
construction activities. Because of the slow speed of hovercraft and 
vessels used for Northstar operations, it is highly unlikely that there 
would be any take from these activities.
    Because BP operates the Northstar facility year-round, take of 
marine mammals could occur at any time of year. However, take of all 
marine mammal species that could potentially occur in the area is not 
anticipated during all seasons. This is because of the distribution and 
habitat preferences of certain species during certain times of the 
year. This is explained further in this section and BP's application 
(see ADDRESSES).

Estimated Takes in the Ice-covered Season

    Potential sources of disturbance to marine mammals from the 
Northstar project during the ice-covered period consist primarily of 
vehicle traffic along the ice-road, helicopter traffic, and the ongoing 
production and drilling operations on the island. During the ice-
covered season, the ringed seal is the only marine mammal that occurs 
regularly in the area of landfast ice surrounding Northstar. Spotted 
seals do not occur in the Beaufort Sea in the ice-covered season. Small 
numbers of bearded seals occur occasionally in the landfast ice in some 
years. Bowhead and beluga whales are absent from the Beaufort Sea in 
winter (or at least from the landfast ice portions of the Beaufort 
Sea), and in spring their eastward migrations are through offshore 
areas north of the landfast ice, which excludes whales from areas close 
to Northstar. Gray whales are also absent from this part of the 
Beaufort Sea during the ice-covered season. Therefore, takes of marine 
mammals during the ice-covered season were only estimated for ringed 
and bearded seals.
    Potential displacement of ringed seals was more closely related to 
physical alteration of sea ice by industry than to exposure to 
detectable levels of low-frequency industrial sound during winter and 
spring (Williams et al., 2006; Richardson et al., 2008b; Moulton et 
al., MS). The distance within which displacement of ringed seals might 
occur near a development like Northstar was defined as the physically 
affected area plus a 328 ft (100 m) buffer zone. A study from a drill 
site in the Canadian Beaufort Sea provided similar results (Harwood et 
al., 2007). The Northstar ice road is typically flooded and thickened 
and/or cleared of snow. The physically affected ice road area is about 
1,312 ft (400 m) wide, and this is extended with 328 ft (100 m) on 
either side to a total width of 1,969 ft (600 m) to derive the zone of 
displacement. This zone of displacement (or impact zone) around 
physically affected areas such as the ice road, work areas on the ice, 
and Northstar Island itself, is used to calculate the number of seals 
potentially affected (Richardson et al., 2008b).
(1) Bearded Seal
    The few bearded seals that remain in the area during winter and 
spring are generally found north of Northstar in association with the 
pack ice or the edge of the landfast ice. Bearded seals were not 
observed on the fast ice during the 1997 or 1998 BP/LGL surveys (G. 
Miller, LGL Ltd., pers. comm.), but small numbers were noted there in 
1999-2002 (Moulton et al., 2003b). No bearded seals were seen during 
spring aerial surveys from Oliktok Point to Flaxman Island (Frost et 
al., 1997, 1998). The large size of this phocid makes it conspicuous to 
observers, reducing the likelihood of missing animals on the ice and 
hence underestimating abundance. Based on available data, and the 
ecology of bearded seals, it is unlikely that more than a few bearded 
seals (and most likely none) will be present in close proximity (<328 
ft [100 m]) to the ice road and Northstar itself during the ice-covered 
season. The most probable number of bearded seals predicted to be 
potentially impacted by Northstar activities during the ice-covered 
season in any one year is zero. However, to allow for unexpected 
circumstances that might lead to take of bearded seals when they are 
present, BP requests take of two bearded seals per year during the ice-
covered period by Level B harassment.
(2) Ringed Seal
    Individual ringed seals in the Northstar area during the ice-
covered season may be displaced a short distance away from the ice road 
corridors connecting the production islands to the mainland. However, 
traffic along the ice roads was at a maximum during the initial 
construction period in 2000, and there was no more than localized 
displacement of ringed seals (Williams et al., 2002, 2006c; Moulton et 
al., 2003a, 2005, MS). Seal densities near Northstar during spring were 
not significantly affected by industrial activities in 2000-2004 
(Moulton et al., 2005, MS). Seal monitoring each spring since 2005, 
based on visual observations from the Northstar module in the May 15-
July 15 period, has shown continued occurrence of ringed seals near 
Northstar facilities, though with large variations within and between 
years (Aerts, 2009). During most of the year, all age and sex classes, 
except for newborn pups, could occur in the Northstar area. In late 
March and April, ringed seals give birth; therefore, at that time of 
year young pups may also be encountered.
    Detailed monitoring of ringed seals near Northstar was done during 
spring and (in some years) winter of 1997 to 2002, including three 
years of Northstar construction and initial oil production (2000-2002). 
During the 2003-2004 and 2004-2005 ice-covered and break-up periods, no 
intensive ringed seal monitoring was required and seal sightings were 
recorded opportunistically from Northstar Island. Since 2005, these 
observations from Northstar have occurred in a more systematic fashion 
from mid-May through mid-July each year, with the main objective to 
document seasonal and annual variations in seals present in an area of 
0.62 mi (1 km) around Northstar (Rodrigues and Williams, 2006; 
Rodrigues and Richardson, 2007; Aerts and Rodrigues, 2008; Aerts, 
2009). BP estimated annual takes of ringed seal based on data collected 
from the intensive aerial monitoring program conducted in 1997-2002.
    The numbers of seals present and potentially affected by Northstar 
activities were estimated using the 1997-2002 seal data according to 
the following steps (see Richardson et al., 2008b for more detail):
    (1) Defining a potential impact zone, i.e., the area within which 
seals might have been affected by Northstar activities. This zone 
consisted of a 328 ft (100 m) buffer around the ice road, work areas on 
the ice, and Northstar Island and covered a total area of approximately 
1.5 mi\2\ (4 km\2\).
    (2) Defining a reference zone, i.e., the area without influence of 
industrial

[[Page 39737]]

activities. This zone was defined as an area at distances of 2.5-6.2 mi 
(4-10 km) from the ice road, work areas on the ice, and Northstar 
Island. The reference zone was used to calculate the number and density 
of ringed seals that one would expect in the potential impact zone if 
there was no industrial activity. Because seal density is related to 
water depth, densities within the reference zone were calculated for 
four categories of water depth. Expected density near Northstar was a 
weighted average of those values (weighting by the proportions of the 
potential impact zone that were within each depth stratum).
    (3) Calculating the expected number of seals present in the 
potential impact zone in the absence of industrial activities (based on 
data from the reference zone) for each year separately. The seal 
density of the reference zone was multiplied by the total area of the 
potential impact zone (1.5 mi\2\ [4 km\2\]) to obtain the maximum 
number of seals that could be present and potentially affected.
    (4) Multiplying the number of seals calculated under step 3 with a 
correction factor of 2.84 (to correct for the ``detection bias'' and 
``availability bias''). ``Detection bias'' refers to the fact that 
aerial surveyors do not see every seal that is on the ice and 
potentially sightable. ``Availability bias'' refers to the fact that 
seals are not always hauled out above the ice and snow, and thus 
available to be seen by aerial surveyors. Those two correction factors 
are based, respectively, on Frost et al. (1988) and Kelly and 
Quakenbush (1990).
    Results of these calculations show that 3-8 seals could be present 
in the potential impact zone (Table 3 in BP's application and Table 3 
in this document). The period 1997-1999 can be considered as a pre-
construction period and 2000-2002 as a construction period, with the 
most intensive construction activities occurring in 2000 and 2001. This 
means that, if there was some displacement of ringed seals away from 
Northstar in the ice-covered season due to construction activities, BP 
would have expected fewer seals within the potential impact zone during 
2000-2002 than in 1997-1999. That was not observed, although inter-year 
comparisons should be treated cautiously given the possibility of year-
to-year differences in environmental conditions and sightability of 
seals during aerial surveys. The presence of numerous seals near the 
Northstar facilities during late spring of 2000, 2001 and 2002 
indicates that any displacement effect was localized and, if it 
occurred at all, involved only a small fraction of the seals that would 
otherwise have been present. To allow for unexpected circumstances that 
might lead to take of ringed seals, BP requests take of eight ringed 
seals per year during the ice-covered period by Level B harassment. In 
the unlikely event that a ringed seal lair is crushed or flooded, BP 
also requests take of up to five ringed seals (including pups) by 
injury or mortality per year.

 Table 3--Numbers of Ringed Seals Expected to Occur in Spring 1997-2002 Within the ``Potential Impact Zone'' in
 the Absence of Any Northstar Impact, Based on Observed Seal Densities in a Reference Area 2.5-6.2 mi (4-10 km)
     Away From Northstar. The potential Impact Zone Included Areas Within 328 ft (100 m) of the Ice Road and
                                Northstar/Seal Island (Richardson et al., 2008b)
----------------------------------------------------------------------------------------------------------------
                                                                                     Expected number of seals
                                                                     Expected      within potential impact zone
                          BP/LGL survey                             density \a\  -------------------------------
                                                                  (seals/km \2\)    Uncorrected    Corrected \b\
----------------------------------------------------------------------------------------------------------------
1997............................................................            0.54               2               6
1998............................................................            0.36               1               4
1999............................................................            0.29               1               3
2000............................................................            0.59               2               7
2001............................................................            0.56               2               6
2002............................................................            0.67               3               8
Average 1997-2002...............................................            0.50               2               6
----------------------------------------------------------------------------------------------------------------
\a\ This is the average uncorrected densities based on data from the zone 4-10 km away from the 2004 development
  zone, controlling for water depth by weighting density based on the proportions of the potential impact zone
  within the various depth strata.
\b\ This is the ``uncorrected'' number multiplied by the 1.22 correction factor for seals hauled out but not
  seen by observers (Frost et al., 1988), and by the 2.33 correction factor for seals not hauled out (Kelly and
  Quakenbush, 1990).

Estimated Takes in the Break-Up Season

    Potential sources of disturbance to marine mammals from the 
Northstar project during the break-up period consist primarily of 
hovercraft and helicopter traffic, as well as the ongoing production 
and drilling operations on the island. Spotted seals and bowhead, gray, 
and beluga whales are expected to be absent from the Northstar project 
area during the break-up period. Therefore, take of those species 
during the break-up period was not estimated.
    Similar to the ice-covered season, BP predicts that only very few 
bearded seals (and most likely none) could be present within the 
potential impact zone around the ice road and Northstar facilities 
during the break-up period. The most probable number of bearded seals 
predicted to be potentially impacted by Northstar activities during 
break-up in any one year is zero. However, to account for the possible 
presence of low numbers of bearded seals during this time, NMFS 
proposes to authorize the take of two bearded seals per year during the 
break-up season.
    Impacts to ringed seals from Northstar activities during the break-
up period are anticipated to be similar to those predicted during the 
ice-covered period. Additionally, the number of ringed seals present 
within the potential impact zone during the break-up period is expected 
to be similar to the number present during the ice-covered season. It 
is possible that some of these seals are the same individuals already 
counted as present during the latter stages of the ice-covered season 
(B. Kelly, pers. comm.). Thus, if any seals were affected during break-
up, it is probable that some of these would be the same individuals. BP 
states that the requested Level B take of eight ringed seals per year 
during the ice-covered periods of 2011-2016 (see preceding subsection) 
is expected to also cover potentially affected seals during break-up. 
However, in case the same seals are taken during both periods, NMFS 
proposes to authorize the take of eight ringed seals by Level B 
harassment per year during the break-up period.

[[Page 39738]]

Estimated Takes in the Open-Water Season

    Potential sources of disturbance to marine mammals from the 
Northstar project during the open-water period consist primarily of 
hovercraft and ACS vessels used for transfers of crew and supplies, 
barge and tugboat traffic, helicopter traffic, and the ongoing 
production and drilling operations on the island. During the open-water 
season all six species for which take authorization is sought can 
potentially be present in the Northstar area. Estimated annual numbers 
of potential open-water takes for each of these six species are 
summarized next.
(1) Spotted Seal
    Pupping and mating occur in the spring when spotted seals are not 
in the Beaufort Sea. Hence, young pups would not be encountered in the 
Northstar Development area. All other sex and age classes may be 
encountered in small numbers during late summer/autumn. Spotted seals 
are most often found in waters adjacent to river deltas during the 
open-water season in the Beaufort Sea, and major haul-out 
concentrations are absent close to the project area. A small number of 
spotted seal haul-outs are (or were) located in the central Beaufort 
Sea in the deltas of the Colville River (which is more than 50 mi [80 
km] from Northstar) and, previously, the Sagavanirktok River. 
Historically, these sites supported as many as 400-600 spotted seals, 
but in the late 1990s, less than 20 seals have been seen at any one 
site (Johnson et al., 1999). In total, there are probably no more than 
a few tens of spotted seals along the coast of the central Alaska 
Beaufort Sea during summer and early fall. No spotted seals were 
positively identified during BP's Northstar marine mammal monitoring 
activities, although a few spotted seals might have been present. A 
total of 12 spotted seals were positively identified near the source 
vessel during open-water seismic programs in the central Alaskan 
Beaufort Sea generally near Northstar from 1996 to 2001 (Moulton and 
Lawson, 2002). Numbers seen per year ranged from zero (in 1998 and 
2000) to four (in 1999). BP, therefore, predicts that it is unlikely 
that any spotted seals will be ``taken'' during Northstar operations. 
However, to account for the possibility that spotted seals could occur 
in small numbers in the proximity of Northstar, NMFS proposes to 
authorize the take of five spotted seals per year during the open-water 
period by Level B harassment.
(2) Bearded Seal
    During the open-water season, bearded seals are widely and sparsely 
distributed in areas of pack ice and open water, including some 
individuals in relatively shallow water as far south as Northstar. 
Studies indicate that pups and other young bearded seals up to 3 years 
of age comprise 40-45% of the population (Nelson et al., n.d.), and 
that younger animals tend to occur closer to shore. Therefore, although 
all age and sex classes could be encountered, bearded seals encountered 
in the Northstar project area during the open-water period are likely 
to be young, non-reproductive animals. Bearded seals, if present, may 
be exposed to noise and other stimuli from production activities and 
vessel and aircraft traffic on and around the island. It is possible 
that some individuals may be briefly disturbed or show localized 
avoidance, but it is not anticipated to have any significant impact on 
the species. BP assumes that brief reactions that do not disrupt 
behavioral patterns in a biologically significant manner (i.e., looking 
at a passing vessel or helicopter) do not constitute harassment (NMFS, 
2000, 2001). Given that and the low number of bearded seals potentially 
present, the estimated number of bearded seal ``takes'' during the 
open-water season is zero. However, to allow for unexpected 
circumstances, BP requests the take of one bearded seal per year during 
the open-water period.
(3) Ringed Seal
    Because ringed seals are resident in the Beaufort Sea, they are the 
most abundant and most frequently encountered seal species in the 
Northstar area. During the open-water period, all sex and age classes 
(except neonates) could potentially be encountered. The estimated 
number of seals that potentially might be harassed by noise from 
Northstar production activities or from vessel and aircraft traffic are 
based on the following three assumptions:
    (1) Seals present within a 0.62 mi (1 km) distance (1.2 mi\2\ [3.1 
km\2\] area) of Northstar might be potentially disturbed by 
construction and other activities on the island.
    (2) The density of seals within that area would be no more than 2x 
the density observed during boat-based surveys for seals within the 
general Prudhoe Bay area in 1996-2001 (0.19 seals/km\2\ x 2 = 0.38 
seals/km\2\; Moulton and Lawson, 2002).
    (3) Individual seals within the affected area are replaced once for 
each of thirteen 7-day intervals during the open-water period (mid July 
to mid October).
    The first of these points assumes that seals in open water are not 
significantly affected by passing vessels (or helicopters) that they 
could occasionally encounter in areas >0.62 mi (1 km) from Northstar. 
Passing boats and helicopters might cause startle reactions and other 
short-term effects.
    Based on the above assumptions, BP estimated that 15 ringed seals 
might be present and potentially affected during the open-water season 
(i.e., 3.1 km\2\ x 0.38 seals/km\2\ x 13 weeks). BP notes that this 
estimate is subject to wide uncertainty (in either direction) given the 
uncertainties in each of the three assumptions listed above. There is 
no specific evidence that any of the seals occurring near Northstar 
during the 1997-2009 open-water seasons were disturbed appreciably or 
otherwise affected by BP's activities (Williams et al., 2006a; Moulton 
et al., 2003a, 2005; Rodrigues et al., 2006; Rodrigues and Richardson, 
2007; Aerts and Rodrigues, 2008; Aerts, 2009). BP requests the take of 
15 ringed seals per year during the open-water season by Level B 
harassment.
(4) Bowhead Whale
    Bowhead whales are not resident in the region of activity. During 
the open-water season, relatively few westward migrating bowheads occur 
within 6.2 mi (10 km) of Northstar during most years. However, in some 
years (especially years with relatively low ice cover) a larger 
percentage of the bowhead population migrates within 6.2-9.3 mi (10-15 
km) of Northstar (Treacy, 1998; Blackwell et al., 2007, 2009). The 
bowhead whale population in the Bering-Chukchi-Beaufort area was 
estimated to include approximately 10,545 animals (CV = 0.128) in 2001. 
To estimate the 2011 population size for purposes of calculating 
potential ``takes'', the annual rate of increase was assumed to be 
steady at 3.4% (George et al., 2004). Based on these figures, the 2011 
population size could be approximately 14,625 bowhead whales.
    About 43.7% of the bowheads in the Bering-Chukchi-Beaufort stock 
are sexually mature (Koski et al., 2004), and about 25% of the mature 
females are pregnant during autumn migration (Zeh et al., 1993). About 
50.5% of the whales in this stock are juveniles (excluding calves), and 
5.8% are calves (Koski et al., 2004). The sex ratio is close to 1:1; 
about half of each category would be males and half females. There are 
few data on the age and sex composition of bowhead whales that have 
been sighted near the Prudhoe Bay area. The few data

[[Page 39739]]

from the area and more extensive data from more easterly parts of the 
Alaskan Beaufort Sea in late summer/autumn (Koski and Johnson, 1987; 
Koski and Miller, 2002, 2009) suggest that almost all age and sex 
categories of bowheads could be encountered, i.e., males, non-pregnant 
females, pregnant females, and calves (mostly 3-6 months old). Newly 
born calves (< 1 month old) are not likely to be encountered during the 
fall (Nerini et al., 1984; Koski et al., 1993). Koski and Miller (2009) 
found that, at least in the more easterly part of the Beaufort Sea, 
subadults were disproportionately present in water < 656 ft (200 m) 
deep, and that small subadult whales were the dominant group in shallow 
(< 66 ft [20 m]) nearshore habitats with the size of whales increasing 
with increasing water depth. The potential take of bowhead whales from 
Northstar activities would be limited to Level B harassment (including 
avoidance reactions and other behavioral changes). Most bowheads that 
could be encountered would be migrating, so it is unlikely that an 
individual bowhead would be harassed more than once.
    The acoustic monitoring of the bowhead whale migration during the 
early years of Northstar operations is described in the final 
Comprehensive Report of 1999-2004 (Richardson [ed.], 2008: Chapters 7-
12). The monitoring was designed to determine whether the southern edge 
of the distribution of calling bowhead whales tended to be farther 
offshore with increased levels of underwater sounds from Northstar 
construction and operational activities. If the southernmost calling 
bowheads detected by the acoustic monitoring system tended to be 
farther offshore when Northstar operations were noisy than when they 
were quieter, this was to be taken as evidence of a Northstar effect. 
The initial monitoring objectives did not call for estimating the 
numbers of bowhead whales that were affected based on the acoustic 
localization data, but this was added as an objective in an updated 
monitoring plan (LGL and Greeneridge, 2000) prepared subsequent to 
issuance of the initial 5-yr regulations in May 2000. It was 
anticipated that the geographic scale of any documented effect, as a 
function of Northstar sound level, would provide a basis for estimating 
the number of whales affected. As early as 2001, it was noted that--
given the difficulty in separating displacement effects from effects on 
calling behavior--the estimates of numbers affected would concern 
numbers of whales whose movements and/or calling behavior were affected 
by Northstar activities (BPXA, 2001).
    In fact, the monitoring results provided evidence (P < 0.01 each 
year) of an effect on the southern part of the migration corridor 
during all four of the autumn migration seasons for which detailed data 
were acquired, i.e., 2001-2004 (McDonald et al., 2008; Richardson and 
McDonald, 2008). In 2001, the apparent southern edge of the 
distribution of calling whales was an estimated 0.95 mi (1.53 km) 
farther offshore when sound at industrial frequencies (28-90 Hz), 
measured 1,444 ft (440 m) from Northstar and averaged over 45 min 
preceding the call, increased from 94.3 to 103.7 dB re 1 [mu]Pa. In 
2002, the apparent southern edge of the call distribution was an 
estimated 1.46 mi (2.35 km) farther offshore during times when 
transient sounds associated with boat traffic were present during the 
preceding 2 hr. In 2003 and 2004, the apparent southern edge was 
estimated to be farther offshore when tones were recorded in the 10-450 
Hz band just prior to the call. In 2003, the apparent offshore shift 
was by an estimated 0.47 mi (0.76 km) when tones were present within 
the preceding 15 min. In 2004, the apparent shift was 1.39 mi (2.24 km) 
when tones were present within the preceding 2 hr.
    Based on the amount of time bowhead whales are expected to be 
present in the general vicinity of the Northstar Development area and 
the fact that most of the whales migrate past the area beyond the 120-
dB sound isopleths (NMFS' threshold for Level B harassment from 
continuous sound sources), which typically extend out less than 1.24-
2.5 mi (2-4 km) from the island, it is estimated that only a small 
number of bowhead whales will be taken by harassment each year as a 
result of BP's activities. Therefore, BP requests the take of 15 
bowhead whales per year during the open-water season by Level B 
harassment.
(5) Gray Whale
    Gray whales are uncommon in the Prudhoe Bay area, with no more than 
a few sightings in summer or early autumn in any one year, and usually 
no sightings (Miller et al., 1999; Treacy, 2000, 2002a,b). During the 
extensive aerial survey programs funded by MMS (Bowhead Whale Aerial 
Survey Program surveys), only one gray whale was sighted in the central 
Alaskan Beaufort Sea from 1979 to 2007. Gray whales were mostly sighted 
around Point Barrow. Small numbers of gray whales were sighted on 
several occasions in the central Alaskan Beaufort, e.g., in the 
Harrison Bay area (Miller et al., 1999; Treacy, 2000), in the Camden 
Bay area (Christie et al., 2009) and one single sighting near Northstar 
production island (Williams and Coltrane, 2002). Several single gray 
whales have been seen farther east in the Canadian Beaufort Sea (Rugh 
and Fraker, 1981; LGL Ltd., unpubl. data), indicating that small 
numbers must travel through the Alaskan Beaufort during some summers. 
Gray whale calls have been recorded northeast of Barrow during the 
winter, indicating that some whales overwinter in the western Beaufort 
Sea (Stafford et al., 2007). Gray whales do not call very often when on 
their summer feeding grounds, and the infrequent calls are not very 
strong (M. Dahlheim and S. Moore, NMFS, pers. comm.). No gray whale 
calls were recognized in the data from the acoustic monitoring system 
near Northstar in 2000-2008. No specific data on age or sex composition 
are available for the few gray whales that move east into the Beaufort 
Sea. All sex and age classes (including pregnant females) could be 
found, with the exception of calves less than six months of age.
    If a few gray whales occur in the Prudhoe Bay area, it is unlikely 
that they would be affected appreciably by Northstar sounds. Gray 
whales typically do not show avoidance of sources of continuous 
industrial sound unless the received broadband level exceeds 
approximately 120 dB re 1 [mu]Pa (Malme et al., 1984, 1988; Richardson 
et al., 1995b; Southall et al., 2007). The broadband received level 
approximately 1,476 ft (450 m) seaward from Northstar did not exceed 
120 dB 1 [mu]Pa in the operational period 2004-2008 (95th percentiles), 
except when a vessel was passing close to Northstar or the acoustic 
recorders (maximum levels). It is possible that one or more gray 
whales, if present, might have been disturbed briefly during close 
approach by a vessel, but no such occurrences were documented in the 
past. It is most likely that no gray whales will be affected by 
activities at Northstar during any one year. However, to account for 
the possibility that a low number of gray whales could occur near 
Northstar, BP requests the take of two gray whales per year during the 
open-water period by Level B harassment.
(6) Beluga Whale
    The Beaufort Sea beluga population was estimated at 39,258 
individuals in 1992, with a maximum annual rate of increase of 4% (Hill 
and DeMaster, 1998; Angliss and Allen, 2009). Assuming a continued 4% 
annual growth rate, the population size could be approximately 79,650 
beluga whales

[[Page 39740]]

in 2011. However, the 4% estimate is a maximum value and does not 
include loss of animals due to subsistence harvest or natural mortality 
factors. Angliss and Allen (2009) consider the current annual rate of 
increase to be unknown. Thus, the population size in 2011 may be less 
than the estimated value. Additionally, the southern edge of the main 
fall migration corridor is approximately 62 mi (100 km) north of the 
Northstar region. A few migrating belugas were observed in nearshore 
waters of the central Alaskan Beaufort Sea by aerial and vessel-based 
surveyors during seismic monitoring programs from 1996-2001 (LGL and 
Greeneridge, 1996a; Miller et al., 1997, 1998b, 1999). Results from 
aerial surveys conducted in 2006-2008 during seismic and shallow hazard 
surveys in the Harrison Bay and Camden Bay area also show that the 
majority of belugas occur along the shelf break, although there were 
some observations in nearshore areas (Christie et al., 2009). Vessel-
based surveyors observed a group of three belugas in Foggy Island Bay 
in July 2008, during BP's Liberty seismic survey (Aerts et al., 2008) 
and small groups of westward traveling belugas have occasionally been 
sighted around Northstar and Endicott, mostly in late July to early/
mid-August (John K. Dorsett, Todd Winkel, BP, pers. comm.). Any 
potential take of these beluga whales in nearshore waters is expected 
to be limited to Level B harassment. Belugas from the Chukchi stock 
occur in the Alaskan Beaufort Sea in summer but are even less likely 
than the Beaufort stock to be encountered in the nearshore areas where 
sounds from Northstar will be audible.
    The few animals involved could include all age and sex classes. 
Calving probably occurs in June to August in the Beaufort Sea region 
and calves 1-4 months of age could be encountered in summer or autumn. 
Most of the few belugas that could be encountered would be engaged in 
migration, so it is unlikely that a given beluga would be repeatedly 
``taken by harassment''.
    Based on available information on the presence and abundance of 
beluga whales, the following data and assumptions were used to estimate 
the number of belugas that could be present and potentially disturbed 
by Northstar activities:
    (1) Aerial survey data from 1979 to 2000, including both MMS and 
LGL surveys, were used to estimate the proportion of belugas migrating 
through waters <= 2.5 mi (4 km) seaward of Northstar. Of the belugas 
traveling through the surveyed waters (generally inshore of the 328-ft 
[100-m] contour), the overall percentage observed in waters offshore of 
Northstar during 1997-2000 was 0.62% (8 of 1,289 belugas). The maximum 
percentage for any one year was for 1996, when 6 of 153 (3.9%) were <= 
2.5 mi (4 km) offshore of Northstar. These figures are based on beluga 
sightings within the area 147[deg]00' to 150[deg]30' W.
    (2) Most beluga whales migrate far offshore; the proportion 
migrating through the surveyed area is unknown but was assumed by 
Miller et al. (1999) to be less than or equal to 20%, which is probably 
an overestimate.
    (3) The disturbance radius for belugas exposed to construction and 
operational activities in the Beaufort Sea is not well defined 
(Richardson et al., 1995a), but BPXA (1999) assumed that the potential 
radius of disturbance was <= 0.62 mi (1 km) around the island. (There 
are no Northstar-specific data that could be used to obtain a better 
estimate than this <= 0.62 mi [1 km] figure.) Based on the assumed 0.62 
mi (1 km) radius, it is expected that no more than 20% of the belugas 
migrating <= 2.5 mi (4 km) seaward of Northstar would approach within 
0.62 mi (1 km) of the Northstar Island in the absence of any industrial 
activity there. However, since the 0.62 mi (1 km) value was arbitrary, 
NMFS calculated take of beluga whales based on the 120-dB radius of 2.5 
mi (4 km).
    (4) Satellite-tagging data show that some members of the Chukchi 
Sea stock of belugas could also occur in the Beaufort Sea generally 
near Northstar during late summer and autumn (Suydam et al., 2001, 
2003). However, they (like the Beaufort belugas) tend to remain at or 
beyond the shelf break when in the Alaskan Beaufort Sea during that 
season. That, combined with the small size of the Chukchi stock, means 
that consideration of Chukchi belugas would not appreciably change the 
estimated numbers of belugas that might occur near Northstar.
    From these values, the number of belugas that might approach within 
2.5 mi (4 km) of Northstar (in the absence of industrial activities) 
during the open water season is approximately 20 belugas based on the 
average distribution: 0.0025 x 0.2 x 39,258. Therefore, NMFS proposes 
to authorize the take of 20 beluga whales per year during the open-
water period by Level B harassment.

Summary of Proposed Take

    BP has requested the take of six marine mammal species incidental 
to operational activities at the Northstar facility. However, because 
some of these species only occur in the Beaufort Sea on a seasonal 
basis, take of all six species has not been requested for an entire 
year. BP broke out its take requests into three seasons: Ice-covered 
season; break-up period; and open-water season. Ringed and bearded 
seals are the only species for which take was requested in all three 
seasons. Take of all six species was only requested for the open-water 
season. With the exception of the request for five ringed seal 
(including pups) takes by injury or mortality per year, all requested 
takes are by Level B harassment.
    Table 4 in this document summarizes the abundance, take estimates, 
and percent of population for the six species for which NMFS is 
proposing to authorize take.

 Table 4--Population Abundance Estimates, Total Annual Proposed Take (When Combining Takes From the Ice-Covered,
 Break-Up, and Open-Water Seasons), and Percentage of Population That May Be Taken for the Potentially Affected
                                                     Species
----------------------------------------------------------------------------------------------------------------
                                                                   Total annual    Total annual    Percentage of
                   Species                         Abundance         proposed        injury or       stock or
                                                                   level B take   mortality take    population
----------------------------------------------------------------------------------------------------------------
Ringed Seal.................................         \1\ 249,000              20               5            0.01
Bearded Seal................................        \1\ 250,000-               5               0          < 0.01
                                                         300,000
Spotted Seal................................          \1\ 59,214               5               0            0.01
Bowhead Whale...............................          \2\ 14,625              15               0            0.1
Beluga Whale................................          \1\ 39,258              39               0            0.1
Gray Whale..................................          \1\ 17,752               2               0            0.01
----------------------------------------------------------------------------------------------------------------
\1\ Abundance estimates in NMFS 2010 Alaska SAR (Allen and Angliss, 2011).
\2\ Estimate from George et al. (2004) with an annual growth rate of 3.4%.


[[Page 39741]]

    Because Prudhoe Bay (and the U.S. Beaufort Sea as a whole) 
represents only a small fraction of the Arctic basin where these 
animals occur, NMFS has preliminarily determined that only small 
numbers of the marine mammal species or stocks in the area would be 
potentially affected by operation of the Northstar facility. The take 
estimates presented in this section of the document do not take into 
consideration the mitigation and monitoring measures that are proposed 
for inclusion in the regulations (if issued).

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 for bearded and spotted 
seals or for bowhead, beluga, and gray whales. There is the potential 
for a small number of injuries or mortalities to ringed seals (no more 
than five per year) as a result of ice road construction activities 
during the ice-covered season. These injuries or mortalities could 
occur if a ringed seal lair is crushed or flooded. Additionally, 
animals in the area are not anticipated to incur any hearing impairment 
(i.e., TTS, a Level B harassment, or PTS, a Level A [injury] 
harassment), as acoustic measurements indicate source levels below 180 
dB and 190 dB, which are the thresholds used by NMFS for acoustic 
injury to marine mammals. All other takes are anticipated to be by 
Level B behavioral harassment only. Certain species may have a 
behavioral reaction (e.g., increased swim speed, avoidance of the area, 
etc.) to the sound emitted during the operational activities. Table 2 
in this document outlines the number of takes that are anticipated as a 
result of BP's proposed activities. These takes are anticipated to be 
of low intensity due to the low level of sound emitted by the majority 
of the activities themselves. Activities occur at Northstar year-round, 
but the majority of these activities produce low-level continuous 
sounds. Only on rare occasions are more high-intensity pulsed sounds 
emitted into the surrounding environment. The ringed seal (and possibly 
the bearded seal) are the only species that occur in the area year-
round.
    Even though activities occur throughout the year, none of the 
cetacean species occur near Northstar all year. Cetaceans are most 
likely to occur in the late summer and autumn seasons. However, even 
during that time, much of the populations of those species migrate past 
the area farther offshore than the area where Northstar sounds can be 
heard. Spotted seals also tend to only be present in the open-water 
season. Moreover, they are more common in the Colville River Delta 
area, which is more than 50 mi (80 km) west of the Northstar 
Development area, than in the waters surrounding Northstar. Ringed and 
bearded seals could be found in the area year-round. However, many of 
them remain far enough from the facility, outside of areas of 
harassment. Additionally, ringed seals have been observed in the area 
every year since the beginning of construction and into the subsequent 
operational years.
    Many animals perform vital functions, such as feeding, resting, 
traveling, and socializing, on a diel cycle (24-hr cycle). Behavioral 
reactions to noise exposure (such as disruption of critical life 
functions, displacement, or avoidance of important habitat) are more 
likely to be significant if they last more than one diel cycle or recur 
on subsequent days (Southall et al., 2007). Consequently, a behavioral 
response lasting less than one day and not recurring on subsequent days 
is not considered particularly severe unless it could directly affect 
reproduction or survival (Southall et al., 2007). Even though 
activities occur on successive days at Northstar, none of the cetacean 
species are anticipated to incur impacts on successive days. In the 
vicinity of Northstar, cetaceans are migrating through the area. 
Therefore, it is unlikely that the same animals are impacted on 
successive days. The closest known bowhead whale feeding ground is 
Camden Bay, which is more than 62 mi (100 km) east of Northstar. The 
same individual bearded and spotted seals are also not likely to occur 
in the proposed project area on successive days. Individual ringed 
seals may occur in the proposed project area on successive days. 
However, monitoring results (which were discussed earlier in this 
document) indicate that operation of the Northstar facility has not 
affected activities such as resting and pupping in the area.
    Of the six marine mammal species for which take authorization is 
proposed, only one is listed as endangered under the ESA: the bowhead 
whale. The bowhead whale is also considered depleted under the MMPA. As 
stated previously in this document, the affected bowhead whale stock 
has been increasing at a rate of 3.4% per year since 2001. Certain 
stocks or populations of gray and beluga whales and spotted seals are 
listed as endangered or are proposed for listing under the ESA; 
however, none of those stocks or populations occur in the proposed 
activity area. On December 10, 2010, NMFS published a notification of 
proposed threatened status for subspecies of the ringed seal (75 FR 
77476) and a notification of proposed threatened and not warranted 
status for subspecies and distinct population segments of the bearded 
seal (75 FR 77496) in the Federal Register. These threatened listings 
will likely be completed prior to the expiration of these regulations 
(if issued). Neither of these two ice seal species is currently 
considered depleted under the MMPA. There is currently no established 
critical habitat in the proposed project area for any of these six 
species.
    The population estimates for the species that may potentially be 
taken as a result of BP's proposed activities were presented earlier in 
this document. For reasons described earlier in this document, the 
maximum calculated number of individual marine mammals for each species 
that could potentially be taken annually is small relative to the 
overall population sizes (less than 1% of each of the six populations 
or stocks).
    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 operation of the BP Northstar 
facility will result in the incidental take of small numbers of marine 
mammals and that the total taking from BP's proposed activities will 
have a negligible impact on the affected species or stocks.

Impact on Availability of Affected Species or Stock for Taking for 
Subsistence Uses

Relevant Subsistence Uses

    The disturbance and potential displacement of marine mammals by 
sounds from island production activities are the principal concerns 
related to subsistence use of the area. However, contamination of 
animals and traditional hunting areas by oil (in the

[[Page 39742]]

unlikely event that an oil spill did occur) is also a concern. 
Subsistence remains the basis for Alaska Native culture and community. 
Marine mammals are legally hunted in Alaskan waters by coastal Alaska 
Natives. In rural Alaska, subsistence activities are often central to 
many aspects of human existence, including patterns of family life, 
artistic expression, and community religious and celebratory 
activities. Additionally, the animals taken for subsistence provide a 
significant portion of the food that will last the community throughout 
the year. The main species that are hunted include bowhead and beluga 
whales, ringed, spotted, and bearded seals, walruses, and polar bears. 
(As mentioned previously in this document, both the walrus and the 
polar bear are under the USFWS' jurisdiction.) The importance of each 
of these species varies among the communities and is largely based on 
availability.
    Residents of the village of Nuiqsut are the primary subsistence 
users in the project area. The communities of Barrow and Kaktovik also 
harvest resources that pass through the area of interest but do not 
hunt in or near the Northstar area. Subsistence hunters from all three 
communities conduct an annual hunt for autumn-migrating bowhead whales. 
Barrow also conducts a bowhead hunt in spring. Residents of all three 
communities hunt seals. Other subsistence activities include fishing, 
waterfowl and seaduck harvests, and hunting for walrus, beluga whales, 
polar bears, caribou, and moose. Relevant harvest data are summarized 
in Tables 8 and 9 in BP's application (see ADDRESSES).
    Nuiqsut is the community closest to the Northstar development 
(approximately 54 mi [87 km] southwest from Northstar). Nuiqsut hunters 
harvest bowhead whales only during the fall whaling season (Long, 
1996). In recent years, Nuiqsut whalers have typically landed three or 
four whales per year (see Table 9 in BP's application). Nuiqsut whalers 
concentrate their efforts on areas north and east of Cross Island, 
generally in water depths greater than 66 ft (20 m; Galginaitis, 2009). 
Cross Island is the principal base for Nuiqsut whalers while they are 
hunting bowheads (Long, 1996). Cross Island is located approximately 
16.8 mi (27 km) east of Northstar.
    Kaktovik whalers search for whales east, north, and occasionally 
west of Kaktovik. Kaktovik is located approximately 124 mi (200 km) 
east of Northstar Island. The westernmost reported harvest location was 
about 13 mi (21 km) west of Kaktovik, near 70[deg]10' N., 144[deg]11' 
W. (Kaleak, 1996). That site is about 112 mi (180 km) east of Northstar 
Island.
    Barrow whalers search for whales much farther from the Northstar 
area--about 155+ mi (250+ km) to the west. However, given the westward 
migration of bowheads in autumn, Barrow (unlike Kaktovik) is 
``downstream'' from the Northstar region during that season. Barrow 
hunters have expressed concern about the possibility that bowheads 
might be deflected offshore by Northstar and then remain offshore as 
they pass Barrow.
    Beluga whales are not a prevailing subsistence resource in the 
communities of Kaktovik and Nuiqsut. Kaktovik hunters may harvest one 
beluga whale in conjunction with the bowhead hunt; however, it appears 
that most households obtain beluga through exchanges with other 
communities. Although Nuiqsut hunters have not hunted belugas for many 
years while on Cross Island for the fall hunt, this does not mean that 
they may not return to this practice in the future. Data presented by 
Braund and Kruse (2009) indicate that only one percent of Barrow's 
total harvest between 1962 and 1982 was of beluga whales and that it 
did not account for any of the harvested animals between 1987 and 1989.
    Ringed seals are available to subsistence users in the Beaufort Sea 
year-round, but they are primarily hunted in the winter or spring due 
to the rich availability of other mammals in the summer. Bearded seals 
are primarily hunted during July in the Beaufort Sea; however, in 2007, 
bearded seals were harvested in the months of August and September at 
the mouth of the Colville River Delta, which is more than 50 mi (80 km) 
from Northstar. However, this sealing area can reach as far east as 
Pingok Island, which is approximately 17 mi (27 km) west of Northstar. 
An annual bearded seal harvest occurs in the vicinity of Thetis Island 
(which is a considerable distance from Northstar) in July through 
August. Approximately 20 bearded seals are harvested annually through 
this hunt. Spotted seals are harvested by some of the villages in the 
summer months. Nuiqsut hunters typically hunt spotted seals in the 
nearshore waters off the Colville River Delta. The majority of the more 
established seal hunts that occur in the Beaufort Sea, such as the 
Colville delta area hunts, are located a significant distance (in some 
instances 50 mi [80 km] or more) from the proposed project area.

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.

    Noise and general activity during BP's proposed drilling program 
have the potential to impact marine mammals hunted by Native Alaskans. 
Additionally, if an oil spill occurred (even though it is unlikely), 
there could be impacts to marine mammals hunted by Native Alaskans and 
to the hunts themselves. 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 divert from their normal migratory 
path by several kilometers. Helicopter activity also has the potential 
to disturb cetaceans and pinnipeds by causing them to vacate the area. 
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.
    Oil spills might affect the hunt for bowhead whales. The harvest 
period for bowhead whales is probably the time of greatest risk that a 
relatively large-scale spill would reduce the availability of bowhead 
whales for subsistence uses. Pipeline spills are possible for the total 
production period of Northstar. Spills could occur at any time of the 
year. However, spills at most times of year would not affect bowheads, 
as bowheads are present near Northstar for only several weeks during 
late summer and early autumn. Bowheads travel along migration corridors 
that are far offshore of the planned production islands and pipelines 
during spring and somewhat offshore of those facilities

[[Page 39743]]

during autumn. Under the prevailing east-wind conditions, oil spills 
from Northstar would not move directly into the main hunting area east 
and north of Cross Island. However, oil spills could extend into the 
hunting area under certain wind and current regimes (Anderson et al., 
1999).
    Even in the case of a major spill, it is unlikely that more than a 
small minority of the bowheads encountered by hunters would be 
contaminated by oil. However, disturbance associated with 
reconnaissance and cleanup activities could affect whales and thus 
accessibility of whales to hunters. In the very unlikely event that a 
major spill incident occurred during the relatively short fall whaling 
season, it is possible that hunting would be affected significantly.
    Ringed seals are more likely than bowheads to be affected by spill 
incidents because they occur in the development areas throughout the 
year and are more likely than whales to occur close to Northstar. Small 
numbers of bearded seals could also be affected, especially by a spill 
during the open-water season. Potential effects on subsistence use of 
seals will still be relatively low, as the areas most likely to be 
affected are not areas heavily used for seal hunting. However, wind and 
currents could carry spilled oil west from Northstar to areas where 
seal hunting occurs. It is possible that oil-contaminated seals could 
be harvested.
    Oil spill cleanup activity could exacerbate and increase 
disturbance effects on subsistence species, cause localized 
displacement of subsistence species, and alter or reduce access to 
those species by hunters. On the other hand, the displacement of marine 
mammals away from oil-contaminated areas by cleanup activities would 
reduce the likelihood of direct contact with oil and thus reduce the 
likelihood of tainting or other impacts on the mammals.
    One of the most persistent effects of EVOS was the reduced harvest 
and consumption of subsistence resources due to the local perception 
that they had been tainted by oil (Fall and Utermohle, 1995). The 
concentrations of petroleum-related aromatic compound (AC) metabolites 
in the bile of harbor seals were greatly elevated in harbor seals from 
oiled areas of Prince William Sound (PWS). Mean concentrations of 
phenanthrene equivalents for oiled seals from PWS were over 70 times 
greater than for control areas and over 20 times higher than for 
presumably unoiled areas of PWS (Frost et al., 1994b). Concentrations 
of hydrocarbons in harbor seal tissues collected in PWS 1 year after 
EVOS were not significantly different from seals collected in non-oiled 
areas; however, average concentrations of AC metabolites in bile were 
still significantly higher than those observed in un-oiled areas (Frost 
et al., 1994b). The pattern of reduced consumption of marine 
subsistence resources by the local population persisted for at least 1 
year. Most affected communities had returned to documented pre-spill 
harvest levels by the third year after the spill. Even then, some 
households in these communities still reported that subsistence 
resources had not recovered to pre-spill levels. Harvest levels of 
subsistence resources for the three communities most affected by the 
spill still were below pre-spill averages even after 3 years. By then, 
the concern was mainly about smaller numbers of animals rather than 
contamination. However, contamination remained an important concern for 
some households (Fall and Utermohle, 1995). As an example, an elder 
stopped eating local salmon after the spill, even though salmon is the 
most important subsistence resource, and he ate it every day up to that 
point. Similar effects could be expected after a spill on the North 
Slope, with the extent of the decline in harvest and use, and the 
temporal duration of the effect, dependent upon the size and location 
of the spill. This analysis reflects the local perception that oil 
spills pose the greatest potential danger associated with offshore oil 
production.

Plan of Cooperation (POC)

    Regulations at 50 CFR 216.104(a)(12) require MMPA authorization 
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 and the Alaska Eskimo Whaling 
Commission (AEWC) established a conflict avoidance agreement to 
mitigate the noise and/or traffic impacts of offshore oil and gas 
production related activities on subsistence whaling. In addition, the 
NSB and residents from Barrow, Nuiqsut, and Kaktovik participated in 
the development of the Final Environmental Impact Statement (FEIS) for 
the Northstar project. Local residents provided traditional knowledge 
of the physical, biological, and human environment, which was 
incorporated into the Northstar FEIS. Also included in the Northstar 
FEIS is information gathered from the 1996 community data collection, 
along with relevant testimony during past public hearings in the 
communities of Barrow, Nuiqsut, and Kaktovik. This data collection has 
helped ensure that the concerns of NSB residents about marine mammals 
and subsistence are taken into account in the development of the 
project designs, permit stipulations, monitoring programs, and 
mitigation measures.
    BP meets annually with communities on the North Slope to discuss 
the Northstar Development project. Stakeholder and peer review meetings 
convened by NMFS have been held at least annually from 1998 to the 
present to discuss proposed monitoring and mitigation plans, and 
results of completed monitoring and mitigation. Those meetings have 
included representatives of the concerned communities, the AEWC, the 
NSB, Federal, state, and university biologists, the Marine Mammal 
Commission, and other interested parties. One function of those 
meetings has been to coordinate planned construction and operational 
activities with subsistence whaling activity. The agreements have and 
likely will address the following: Operational agreement and 
communications procedures; when/where agreement becomes effective; 
general communications scheme, by season; Northstar Island operations, 
by season; conflict avoidance; seasonally sensitive areas; vessel 
navigation; air navigation; marine mammal and acoustic monitoring 
activities; measures to avoid impacts to marine mammals; measures to 
avoid impacts in areas of active whaling; emergency assistance; and 
dispute resolution process.
    Most vessel and helicopter traffic will occur inshore of the 
bowhead migration corridor. BP does not often approach bowhead whales 
with these vessels or aircraft. Insofar as possible, BP will ensure 
that vessel traffic near areas of particular concern for whaling will 
be completed before the end of August, as the fall bowhead hunts in 
Kaktovik and Cross Island (Nuiqsut) typically begin around September 1 
each year. Additionally, any approaches of bowhead whales by vessels or 
helicopters will not occur within the area where Nuiqsut hunters 
typically search for bowheads. Essential traffic to and from Northstar 
has been and will continue to be closely coordinated with the NSB and 
AEWC to avoid disruptions of subsistence activities. Unless limited by 
weather conditions, BP maintains a minimum flight altitude of 1,000 ft 
(305 m), except during takeoffs and landings, and all helicopter 
transits occur in a specified corridor from the mainland.

[[Page 39744]]

Unmitigable Adverse Impact Analysis and Preliminary Determination

    NMFS has preliminarily determined that BP's proposed operation of 
the Northstar facility will not have an unmitigable adverse impact on 
the availability of marine mammal species or stocks for taking for 
subsistence uses. This preliminary determination is supported by the 
fact that BP works closely with the NSB, AEWC, and hunters of Nuiqsut 
to ensure that impacts are avoided or minimized during the annual fall 
bowhead whale hunt at Cross Island (the closest whale hunt to 
Northstar). Vessel and air traffic will be kept to a minimum during the 
bowhead hunt in order to keep from harassing the animals, which could 
possibly make them more difficult to hunt. To minimize the potential 
for conflicts with subsistence users, marine vessels transiting between 
Prudhoe Bay or West Dock and Northstar Island travel shoreward of the 
barrier islands as much as possible and avoid the Cross Island area 
during the bowhead hunting season in autumn. The fall hunt at Kaktovik 
occurs well to the east of Northstar (approximately 124 mi [200 km] 
away), so there should be no impacts to hunters of that community, 
since the whales will reach Kaktovik well before they enter areas that 
may be ensonified by activities at Northstar. Barrow is more than 155 
mi (250 km) west of Northstar. Even though the whales will have to pass 
by Northstar before reaching Barrow for the fall hunt, the community is 
well beyond the range of detectable noise from Northstar. In the 
spring, the whales will reach Barrow before Northstar. Therefore, no 
impacts are anticipated on the spring bowhead whale hunt for the Barrow 
community.
    Beluga whales are not a primary target of subsistence hunts by the 
Beaufort Sea communities. However, Nuiqsut whalers at Cross Island have 
been known to take a beluga in conjunction with the fall bowhead whale 
hunt. Therefore, the reasons stated previously regarding no unmitigable 
adverse impact to bowhead hunting at Cross Island are also applicable 
to beluga hunts. Additionally, should Kaktovik or Barrow conduct a 
beluga hunt, the distance from Northstar of these two communities would 
ensure no unmitigable adverse impact to those hunts.
    Subsistence hunts of ice seals can occur year-round in the Beaufort 
Sea. However, hunts do not typically occur in the direct vicinity of 
Northstar. Some of the more established seal hunts occur in areas more 
than 20-30 mi (32-48 km) from Northstar. It is not anticipated that 
there would be any impacts to the seals themselves that would make them 
unavailable to Native Alaskans. Additionally, there is not anticipated 
to be any adverse effects to the hunters due to conflicts with them in 
traditional hunting grounds.
    In the unlikely event of a major oil spill that spread into 
Beaufort Sea ice or water, there could be major impacts on the 
availability of marine mammals for subsistence uses. As discussed 
earlier in this document, the probability of a major oil spill 
occurring over the life of the project is low (S.L. Ross Environmental 
Research Ltd., 1998). Additionally, BP developed an oil spill 
prevention and contingency response plan, which was approved by several 
Federal agencies, including the U.S. Coast Guard. BP also conducts 
routine inspections of and maintenance on the pipeline (as described 
earlier in this document; see the ``Expected Activities in 2011-2016'' 
section) to help reduce the likelihood of a major oil spill. To help 
with preparedness in the event of a major oil spill, BP conducts 
emergency and oil spill response training activities at various times 
throughout the year. Equipment and techniques used during oil spill 
response exercises are continually updated.
    Based on the measures described in BP's POC, 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 operation of the Northstar facility. Even 
though there could be unmitigable adverse impacts on subsistence uses 
from a major oil spill, because of the low probability of such an event 
occurring and the measures that BP implements to reduce the likelihood 
of a major oil spill, NMFS has preliminarily determined that there will 
not be an unmitigable adverse impact to subsistence uses from an oil 
spill at Northstar.

Endangered Species Act (ESA)

    On March 4, 1999, NMFS concluded consultation with the U.S. Army 
Corps of Engineers on permitting the construction and operation of the 
Northstar site. The finding of that consultation was that construction 
and operation at Northstar is not likely to jeopardize the continued 
existence of the bowhead whale. Since no critical habitat has been 
established for that species, the consultation also concluded that none 
would be affected.
    The bowhead whale is still the only species listed as endangered 
under the ESA found in the proposed project area. However, on December 
10, 2010, NMFS published notification of proposed threatened status for 
subspecies of the ringed seal (75 FR 77476) and notification of 
proposed threatened and not warranted status for subspecies and 
distinct population segments of the bearded seal (75 FR 77496) in the 
Federal Register. These species will likely be listed as threatened 
under the ESA prior to expiration of these regulations (if issued). 
Therefore, the NMFS Permits, Conservation and Education Division will 
consult with the NMFS Endangered Species Division on the issuance of 
regulations and subsequent LOAs under section 101(a)(5)(A) of the MMPA 
for this activity. This consultation will be concluded prior to a 
determination on the issuance of the final rule and will be taken into 
account in decision-making on the final rule and LOA.

National Environmental Policy Act (NEPA)

    On February 5, 1999 (64 FR 5789), the Environmental Protection 
Agency noted the availability for public review and comment of a FEIS 
prepared by the U.S. Army Corps of Engineers under NEPA on Beaufort Sea 
oil and gas development at Northstar. Based upon a review of the FEIS 
and comments received on the Draft and Final EIS, NMFS adopted the FEIS 
on May 18, 2000. Because of the age of the FEIS and the availability of 
new scientific information, NMFS is currently conducting a new 
analysis, pursuant to NEPA, to determine whether or not the issuance of 
MMPA rulemaking and subsequent LOA(s) may have a significant effect on 
the human environment. This analysis will be completed prior to the 
issuance or denial of these proposed regulations and will be taken into 
account in decision-making on the final rule and LOA.

Classification

    OMB has determined that this proposed rule is not significant for 
purposes of Executive Order 12866.
    Pursuant to section 605(b) of the Regulatory Flexibility Act (RFA), 
the Chief Counsel for Regulation of the Department of Commerce has 
certified to the Chief Counsel for Advocacy of the Small Business 
Administration that this proposed rule, if adopted, would not have a 
significant economic impact on a substantial number of small entities. 
BP Exploration (Alaska) Inc. is the only entity that would be subject 
to the requirements in these proposed regulations. BP Exploration 
(Alaska) Inc. is an upstream strategic performance

[[Page 39745]]

unit of the BP Group. Globally, BP ranks among the 10 largest oil 
companies and is the fourth largest corporation. In 2008, BP 
Exploration (Alaska) Inc. had 2,000 employees alone, and, as of 
December 31, 2009, BP Group had more than 80,000 employees worldwide. 
Therefore, it is not a small governmental jurisdiction, small 
organization, or small business, as defined by the RFA. Because of this 
certification, a regulatory flexibility analysis is not required and 
none has been prepared.
    Notwithstanding any other provision of law, no person is required 
to respond to nor shall a person be subject to a penalty for failure to 
comply with a collection of information subject to the requirements of 
the Paperwork Reduction Act (PRA) unless that collection of information 
displays a currently valid OMB control number. This proposed rule 
contains collection-of-information requirements subject to the 
provisions of the PRA. These requirements have been approved by OMB 
under control number 0648-0151 and include applications for 
regulations, subsequent LOAs, and reports. Send comments regarding any 
aspect of this data collection, including suggestions for reducing the 
burden, to NMFS and the OMB Desk Officer (see ADDRESSES).

List of Subjects in 50 CFR Part 217

    Exports, Fish, Imports, Indians, Labeling, Marine mammals, 
Penalties, Reporting and recordkeeping requirements, Seafood, 
Transportation.

    Dated: June 23, 2011.
John Oliver,
Deputy Assistant Administrator for Operations, National Marine 
Fisheries Service.

    For reasons set forth in the preamble, 50 CFR part 217 is proposed 
to be amended as follows:

PART 217--REGULATIONS GOVERNING THE TAKE OF MARINE MAMMALS 
INCIDENTAL TO SPECIFIED ACTIVITIES

    1. The authority citation for part 217 continues to read as 
follows:

    Authority: 16 U.S.C. 1361 et seq.

    2. Subpart O is added to part 217 to read as follows:
Subpart O--Taking of Marine Mammals Incidental to Operation of Offshore 
Oil and Gas Facilities in the U.S. Beaufort Sea
Sec.
217.140 Specified activity and specified geographical region.
217.141 Effective dates.
217.142 Permissible methods of taking.
217.143 Prohibitions.
217.144 Mitigation.
217.145 Measures to ensure availability of species for subsistence 
uses.
217.146 Requirements for monitoring and reporting.
217.147 Applications for Letters of Authorization.
217.148 Letters of Authorization.
217.149 Renewal of Letters of Authorization and adaptive management.
217.150 Modifications of Letters of Authorization.

Subpart O--Taking of Marine Mammals Incidental to Operation of 
Offshore Oil and Gas Facilities in the U.S. Beaufort Sea


Sec.  217.140  Specified activity and specified geographical region.

    (a) Regulations in this subpart apply only to BP Exploration 
(Alaska) Inc. (BP) and those persons it authorizes to conduct 
activities on its behalf for the taking of marine mammals that occurs 
in the area outlined in paragraph (b) of this section and that occurs 
incidental to operation of offshore oil and gas facilities in the U.S. 
Beaufort Sea, Alaska, in the Northstar Development Area.
    (b) The taking of marine mammals by BP may be authorized in a 
Letter of Authorization only if it occurs in the geographic region that 
encompasses the Northstar Oil and Gas Development area within state 
and/or Federal waters in the U.S. Beaufort Sea.


Sec.  217.141  Effective dates.

    Regulations in this subpart become effective upon issuance of the 
final rule.


Sec.  217.142  Permissible methods of taking.

    (a) Under Letters of Authorization issued pursuant to Sec. Sec.  
216.106 and 217.148 of this chapter, the Holder of the Letter of 
Authorization (hereinafter ``BP'') may incidentally, but not 
intentionally, take marine mammals within the area described in Sec.  
217.140(b), provided the activity is in compliance with all terms, 
conditions, and requirements of the regulations in this subpart and the 
appropriate Letter of Authorization.
    (b) The activities identified in Sec.  217.140(a) must be conducted 
in a manner that minimizes, to the greatest extent practicable, any 
adverse impacts on marine mammals and their habitat.
    (c) The incidental take of marine mammals under the activities 
identified in Sec.  217.140(a) is limited to the following species and 
by the indicated method and amount of take:
    (1) Level B Harassment:

(i) Cetaceans:
    (A) Bowhead whale (Balaena mysticetus)--75 (an average of 15 
annually)
    (B) Gray whale (Eschrichtius robustus)--10 (an average of 2 
annually)
    (C) Beluga whale (Delphinapterus leucas)--100 (an average of 20 
annually)
(ii) Pinnipeds:
    (A) Ringed seal (Phoca hispida)--155 (an average of 31 annually)
    (B) Bearded seal (Erignathus barbatus)--25 (an average of 5 
annually)
    (C) Spotted seal (Phoca largha)--25 (an average of 5 annually)

    (2) Level A Harassment and Mortality: Ringed seal--25 (an average 
of 5 annually)


Sec.  217.143  Prohibitions.

    Notwithstanding takings contemplated in Sec.  217.140 and 
authorized by a Letter of Authorization issued under Sec. Sec.  216.106 
and 217.148 of this chapter, no person in connection with the 
activities described in Sec.  217.140 may:
    (a) Take any marine mammal not specified in Sec.  217.142(c);
    (b) Take any marine mammal specified in Sec.  217.142(c) other than 
by incidental take as specified in Sec. Sec.  217.142(c)(1) and (c)(2);
    (c) Take a marine mammal specified in Sec.  217.172(c) if such 
taking results in more than a negligible impact on the species or 
stocks of such marine mammal;
    (d) Take a marine mammal specified in Sec.  217.172(c) if such 
taking results in an unmitigable adverse impact on the species or stock 
for taking for subsistence uses; or
    (e) Violate, or fail to comply with, the terms, conditions, and 
requirements of this subpart or a Letter of Authorization issued under 
Sec. Sec.  216.106 and 217.148 of this chapter.


Sec.  217.144  Mitigation.

    (a) When conducting the activities identified in Sec.  217.140(a), 
the mitigation measures contained in the Letter of Authorization issued 
under Sec. Sec.  216.106 and 217.148 must be implemented. These 
mitigation measures include but are not limited to:
    (1) Ice-covered Season:
    (i) In order to reduce the taking of ringed seals to the lowest 
level practicable, BP must begin winter construction activities, 
principally ice roads, as soon as possible once weather and ice 
conditions permit such activity.
    (ii) Any ice roads or other construction activities that are 
initiated after March 1, in previously undisturbed areas in waters 
deeper than 10 ft (3 m), must be surveyed, using trained dogs in order 
to identify and avoid ringed seal

[[Page 39746]]

structures by a minimum of 492 ft (150 m).
    (iii) After March 1 of each year, activities should avoid, to the 
greatest extent practicable, disturbance of any located seal structure.
    (2) Open-water Season:
    (i) BP will establish and monitor, during all daylight hours, a 190 
dB re 1 [mu]Pa (rms) safety zone for seals around the island for all 
activities with sound pressure levels (SPLs) that are expected to 
exceed that level in waters beyond the Northstar facility on Seal 
Island.
    (ii) BP will establish and monitor, during all daylight hours, a 
180 dB re 1 [mu]Pa (rms) safety zone for whales around the island for 
all activities with SPLs that are expected to exceed that level in 
waters beyond the Northstar facility at Seal Island.
    (iii) If any marine mammals are observed within the relevant safety 
zone, described in Sec.  217.144(a)(2)(i) or (ii), the activity 
creating the noise will shutdown or reduce its SPL sufficiently to 
ensure that received SPLs do not exceed those prescribed SPL 
intensities at the affected marine mammal. The shutdown or reduced SPL 
shall be maintained until such time as the observed marine mammal(s) 
has been seen to have left the applicable safety zone or until 15 
minutes have elapsed in the case of a pinniped or odontocete or 30 
minutes in the case of a mysticete without resighting, whichever occurs 
sooner.
    (iv) The entire safety zones prescribed in Sec.  217.144(a)(2)(i) 
or (ii) must be visible during the entire 30-minute pre-activity 
monitoring time period in order for the activity to begin.
    (v) New drilling into oil-bearing strata shall not take place 
during either open-water or spring-time broken ice conditions.
    (vi) All non-essential boats, barge, and air traffic will be 
scheduled to avoid periods when bowhead whales are migrating through 
the area where they may be affected by noise from these activities.
    (3) Helicopter flights to support Northstar activities must be 
limited to a corridor from Seal Island to the mainland, and, except 
when limited by weather or personnel safety, must maintain a minimum 
altitude of 1,000 ft (305 m), except during takeoff and landing.
    (4) Additional mitigation measures as contained in a Letter of 
Authorization issued under Sec. Sec.  216.106 and 217.148 of this 
chapter.
    (b) [Reserved]


Sec.  217.145  Measures to ensure availability of species for 
subsistence uses.

    When applying for a Letter of Authorization pursuant to Sec.  
217.147 or a renewal of a Letter of Authorization pursuant to Sec.  
217.149, BP must submit a Plan of Cooperation that identifies what 
measures have been taken and/or will be taken to minimize any adverse 
effects on the availability of marine mammal species or stocks for 
taking for subsistence uses. A plan shall include the following:
    (a) A statement that the applicant has notified and met with the 
affected subsistence communities to discuss proposed activities and to 
resolve potential conflicts regarding timing and methods of operation;
    (b) A description of what measures BP has taken and/or will take to 
ensure that the proposed activities will not interfere with subsistence 
whaling or sealing; and
    (c) What plans BP has to continue to meet with the affected 
communities to notify the communities of any changes in operation.


Sec.  217.146  Requirements for monitoring and reporting.

    (a) BP must notify the Alaska Regional Office, NMFS, within 48 
hours of starting ice road construction, cessation of ice road usage, 
and the commencement of icebreaking activities for the Northstar 
facility.
    (b) BP must designate qualified, on-site individuals, approved in 
advance by NMFS, to conduct the mitigation, monitoring, and reporting 
activities specified in the Letter of Authorization issued under 
Sec. Sec.  216.106 and 217.148 of this chapter.
    (c) Monitoring measures during the ice-covered season shall 
include, but are not limited to, the following:
    (1) After March 1, trained dogs must be used to detect seal lairs 
in previously undisturbed areas that may be potentially affected by on-
ice construction activity, if any. Surveys for seal structures should 
be conducted to a minimum distance of 492 ft (150 m) from the outer 
edges of any disturbance.
    (2) If ice road construction occurs after March 1, conduct a 
follow-up assessment in May of that year of the fate of all seal 
structures located during monitoring conducted under Sec.  
217.146(c)(1) near the physically disturbed areas.
    (3) BP shall conduct acoustic measurements to document sound 
levels, characteristics, and transmissions of airborne sounds with 
expected source levels of 90 dBA or greater created by on-ice activity 
at Northstar that have not been measured in previous years. In 
addition, BP shall conduct acoustic measurements to document sound 
levels, characteristics, and transmissions of airborne sounds for 
sources on Northstar Island with expected received levels at the 
water's edge that exceed 90 dBA that have not been measured in previous 
years.
    (d) Monitoring measures during the open-water season shall include, 
but are not limited to, the following:
    (1) Acoustic monitoring of the bowhead whale migration.
    (2) BP shall monitor the safety zones of activities capable of 
producing pulsed underwater sound with levels >=180 or >=190 dB re 1 
[micro]Pa (rms) at locations where whales or seals could be exposed. At 
least one on-island observer shall be stationed at a location providing 
an unobstructed view of the predicted safety zone. The observer(s) 
shall scan the safety zone continuously for marine mammals for 30 
minutes prior to the operation of the sound source. Observations shall 
continue during all periods of operation. The observer shall record 
the: Species and numbers of marine mammals seen within the 180 or 190 
dB zones; bearing and distance of the marine mammals from the 
observation point; and behavior of marine mammals and any indication of 
disturbance reactions to the monitored activity.
    (e) BP shall conduct any additional monitoring measures contained 
in a Letter of Authorization issued under Sec. Sec.  216.106 and 
217.148 of this chapter.
    (f) BP shall submit an annual report to NMFS within the time period 
specified in a Letter of Authorization issued under Sec. Sec.  216.106 
and 217.148 of this chapter.
    (g) If specific mitigation and monitoring are required for 
activities on the sea ice initiated after March 1 (requiring searches 
with dogs for lairs), during the operation of strong sound sources 
(requiring visual observations and shutdown procedures), or for the use 
of new sound sources that have not previously been measured, then a 
preliminary summary of the activity, method of monitoring, and 
preliminary results shall be submitted to NMFS within 90 days after the 
cessation of that activity. The complete description of methods, 
results, and discussion shall be submitted as part of the annual 
report.
    (h) BP shall submit a draft comprehensive report to NMFS, Office of 
Protected Resources, and NMFS, Alaska Regional Office (specific contact 
information to be provided in Letter of Authorization), no later than 
240 days prior to the expiration of these regulations. This 
comprehensive technical report shall provide full

[[Page 39747]]

documentation of methods, results, and interpretation of all monitoring 
during the first four and a quarter years of the LOA. Before acceptance 
by NMFS as a final comprehensive report, the draft comprehensive report 
shall be subject to review and modification by NMFS scientists.
    (i) Any observations concerning possible injuries, mortality, or an 
unusual marine mammal mortality event shall be transmitted to NMFS, 
Office of Protected Resources, and the Alaska Stranding and 
Disentanglement Program (specific contact information to be provided in 
Letter of Authorization), within 48 hours of the discovery. At a 
minimum, reported information shall include: The time, date, and 
location (latitude/longitude) of the animal(s); the species 
identification or description of the animal(s); the fate of the 
animal(s), if known; and photographs or video footage of the animal (if 
equipment is available).


Sec.  217.147  Applications for Letters of Authorization.

    (a) To incidentally take marine mammals pursuant to these 
regulations, the U.S. Citizen (as defined by Sec.  216.103) conducting 
the activity identified in Sec.  217.140(a) (i.e., BP) must apply for 
and obtain either an initial Letter of Authorization in accordance with 
Sec.  217.148 or a renewal under Sec.  217.149.
    (b) [Reserved]


Sec.  217.148  Letters of Authorization.

    (a) A Letter of Authorization, unless suspended or revoked, shall 
be valid for a period of time not to exceed the period of validity of 
this subpart.
    (b) The Letter of Authorization shall set forth:
    (1) Permissible methods of incidental taking;
    (2) Means of effecting the least practicable adverse impact on the 
species, its habitat, and on the availability of the species for 
subsistence uses (i.e., mitigation); and
    (3) Requirements for mitigation, monitoring and reporting.
    (c) Issuance and renewal of the Letter of Authorization shall be 
based on a determination that the total number of marine mammals taken 
by the activity as a whole will have no more than a negligible impact 
on the affected species or stock of marine mammal(s) and will not have 
an unmitigable adverse impact on the availability of species or stocks 
of marine mammals for taking for subsistence uses.


Sec.  217.149  Renewal of Letters of Authorization and adaptive 
management.

    (a) A Letter of Authorization issued under Sec.  216.106 and Sec.  
217.148 of this chapter for the activity identified in Sec.  217.140(a) 
shall be renewed upon request by the applicant or determination by NMFS 
and the applicant that modifications are appropriate pursuant to the 
adaptive management component of these regulations, provided that:
    (1) NMFS is notified that the activity described in the application 
submitted under Sec.  217.147 will be undertaken and that there will 
not be a substantial modification to the described work, mitigation or 
monitoring undertaken during the upcoming 12 months;
    (2) NMFS recieves the monitoring reports required under Sec.  
217.146(f) and (g); and
    (3) NMFS determines that the mitigation, monitoring and reporting 
measures required under Sec. Sec.  217.144 and 217.146 and the Letter 
of Authorization issued under Sec. Sec.  216.106 and 217.148 of this 
chapter were undertaken and will be undertaken during the upcoming 
annual period of validity of a renewed Letter of Authorization.
    (b) If either a request for a renewal of a Letter of Authorization 
issued under Sec. Sec.  216.106 and 217.149 of this chapter or a 
determination by NMFS and the applicant that modifications are 
appropriate pursuant to the adaptive management component of these 
regulations indicates that a substantial modification, as determined by 
NMFS, to the described work, mitigation or monitoring undertaken during 
the upcoming season will occur, NMFS will provide the public a period 
of 30 days for review and comment on the request. Review and comment on 
renewals of Letters of Authorization are restricted to:
    (1) New cited information and data indicating that the 
determinations made in this document are in need of reconsideration, 
and
    (2) Proposed substantive changes to the mitigation and monitoring 
requirements contained in these regulations or in the current Letter of 
Authorization.
    (c) A notice of issuance or denial of a renewal of a Letter of 
Authorization will be published in the Federal Register.
    (d) Adaptive Management--NMFS may modify or augment the existing 
mitigation or monitoring measures (after consulting with BP regarding 
the practicability of the modifications) if doing so creates a 
reasonable likelihood of more effectively accomplishing the goals of 
mitigation and monitoring set forth in the preamble of these 
regulations. Below are some of the possible sources of new data that 
could contribute to the decision to modify the mitigation or monitoring 
measures:
    (1) Results from BP's monitoring from the previous year;
    (2) Results from general marine mammal and sound research; or
    (3) Any information which reveals that marine mammals may have been 
taken in a manner, extent or number not authorized by these regulations 
or subsequent LOAs.


Sec.  217.150  Modifications of Letters of Authorization.

    (a) Except as provided in paragraph (b) of this section, no 
substantive modification (including withdrawal or suspension) to the 
Letter of Authorization issued by NMFS, pursuant to Sec. Sec.  216.106 
and 217.148 of this chapter and subject to the provisions of this 
subpart, shall be made until after notification and an opportunity for 
public comment has been provided. For purposes of this paragraph, a 
renewal of a Letter of Authorization under Sec.  217.149, without 
modification (except for the period of validity), is not considered a 
substantive modification.
    (b) If the Assistant Administrator determines that an emergency 
exists that poses a significant risk to the well-being of the species 
or stocks of marine mammals specified in Sec.  217.142(c), a Letter of 
Authorization issued pursuant to Sec. Sec.  216.106 and 217.148 of this 
chapter may be substantively modified without prior notification and an 
opportunity for public comment. Notification will be published in the 
Federal Register within 30 days subsequent to the action.

[FR Doc. 2011-16327 Filed 7-5-11; 8:45 am]
BILLING CODE 3510-22-P