# Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to Marine Seismic Survey in the Beaufort and Chukchi Seas, Alaska

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URL: https://www.frixlaw.com/law-library/documents/fr%3A2012-20173

## Record

- **Collection:** Federal Register
- **Document type:** Notice
- **Published:** August 17, 2012
- **Citation:** 77 FR 49922

## Text

DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
RIN 0648-XC091
Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to Marine Seismic Survey in the Beaufort and Chukchi Seas, Alaska

AGENCY:

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

ACTION:

Notice; proposed incidental harassment authorization; request for comments.

SUMMARY:

NMFS received an application from ION Geophysical (ION) for an Incidental Harassment Authorization (IHA) to take marine mammals, by harassment only, incidental to a proposed marine seismic survey in the Beaufort and Chukchi Seas, Alaska, between October and December 2012. Pursuant to the Marine Mammal Protection Act (MMPA), NMFS is requesting comments on its proposal to issue an IHA to ION to take, by harassment, nine species of marine mammals during the specified activity.

DATES:

Comments and information must be received no later than September 17, 2012.

ADDRESSES:

Comments on the application should be addressed to Michael Payne, Chief, Permits and Conservation Division, Office of Protected Resources, National Marine Fisheries Service, 1315 East-West Highway, Silver Spring, MD 20910. The mailbox address for providing email comments is
itp.guan@noaa.gov.
NMFS is not responsible for email comments sent to addresses other than the one provided here. Comments sent via email, including all attachments, must not exceed a 25-megabyte file size.

Instructions:
All comments received are a part of the public record and will generally be posted to
http://www.nmfs.noaa.gov/pr/permits/incidental.htm#applications
without change. All Personal Identifying Information (for example, name, address, etc.) voluntarily submitted by the commenter may be publicly accessible. Do not submit Confidential Business Information or otherwise sensitive or protected information.

An electronic copy of the application used in this document may be obtained by writing to the address specified above, telephoning the contact listed below (see
FOR FURTHER INFORMATION CONTACT
), or visiting the internet at:
http://www.nmfs.noaa.gov/pr/permits/incidental.htm#applications.
The following associated document is also available at the same internet address: Draft Plan of Cooperation. Documents cited in this notice may also be viewed, by appointment, during regular business hours, at the aforementioned address.

FOR FURTHER INFORMATION CONTACT:

Shane Guan, Office of Protected Resources, NMFS, (301) 427-8401.

SUPPLEMENTARY INFORMATION:

Background

Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361
et seq.
) direct the Secretary of Commerce to allow, upon request, the incidental, but not intentional, taking of small numbers of marine mammals by U.S. citizens who engage in a specified activity (other than commercial fishing) within a specified geographical region if certain findings are made and either regulations are issued or, if the taking is limited to harassment, a notice of a proposed authorization is provided to the public for review.

An authorization for incidental takings shall be granted if NMFS finds that the taking will have a negligible impact on the species or stock(s), will not have an unmitigable adverse impact on the availability of the species or stock(s) for subsistence uses (where relevant), and if the permissible methods of taking and requirements pertaining to the mitigation, monitoring and reporting of such takings are set forth. NMFS has defined “negligible impact” in 50 CFR 216.103 as “* * * an impact resulting from the specified activity that cannot be reasonably expected to, and is not reasonably likely to, adversely affect the species or stock through effects on annual rates of recruitment or survival.”

Section 101(a)(5)(D) of the MMPA established an expedited process by which citizens of the U.S. can apply for a one-year authorization to incidentally take small numbers of marine mammals by harassment, provided that there is no potential for serious injury or mortality to result from the activity. Section 101(a)(5)(D) establishes a 45-day time limit for NMFS review of an application followed by a 30-day public notice and comment period on any proposed authorizations for the incidental harassment of marine mammals. Within 45 days of the close of the comment period, NMFS must either issue or deny the authorization.

Except with respect to certain activities not pertinent here, the MMPA defines “harassment” as: Any act of pursuit, torment, or annoyance which (i) has the potential to injure a marine mammal or marine mammal stock in the wild [“Level A harassment”]; or (ii) has the potential to disturb a marine mammal or marine mammal stock in the wild by causing disruption of behavioral patterns, including, but not limited to, migration, breathing, nursing, breeding, feeding, or sheltering [“Level B harassment”].

Summary of Request

NMFS received an application on March 1, 2012, from ION for the taking, by harassment, of marine mammals incidental to a marine seismic survey in ice in the Beaufort and Chukchi Seas, Alaska, during October through December 2012. After addressing comments from NMFS, ION modified its application and submitted a revised application on June 11, 2012. The June 11, 2012, application is the one available for public comment (see
ADDRESSES
) and considered by NMFS for this proposed IHA. ION also submitted IHA applications for essentially the same in-ice seismic survey activity in 2010 and 2011. However, in both years ION withdrew its applications due to logistical issues in carrying out such activities before NMFS published a notice of proposed IHA and request for public comments. Take by Level B harassment only of nine species of marine mammals is anticipated to result from the specified activity. ION has also requested authorization for Level A harassment of a few individuals of bowhead whale, beluga whale, and ringed seal.

Description of the Specified Activity

ION's proposed activities consist of a geophysical in-ice (seismic reflection/refraction) survey and related vessel operations to be conducted primarily in the Alaskan Beaufort and Chukchi seas from October to December 2012. The primary survey area extends from the U.S.-Canadian border in the east to Point Barrow in the west. Two survey lines extend west of Point Barrow into the northern Chukchi Sea, and three short tie lines are proposed near the U.S.-Russian border (see Figure 1 of ION's IHA application). The bathymetry of the proposed survey area ranges from shallow (<20 m [66 ft]) to relatively deep (>3,500 m [11,483 ft]) water over the continental shelf, the continental slope, and the abyssal plain.

The survey would be conducted from the seismic vessel
Geo Arctic
escorted by the
Polar Prince,
a medium class (100A) icebreaker. The survey grid consists of ~7,175 km (4,458 mi) of transect line, not including transits

when the airguns are not operating. There may be small amounts of additional seismic operations associated with airgun testing, start up, and repeat coverage of any areas where initial data quality is sub-standard. The seismic source towed by the
Geo Arctic
would be an airgun array consisting of 26 active Sercel G-gun airguns with a total volume of 4,450 in
3
. A single hydrophone streamer 4.5-9 km (2.8-5.6 mi) in length, depending on ice conditions, would be towed by the
Geo Arctic
to record the returning seismic signals.

The survey vessels would access the survey area from Canadian waters in late September to begin data collection on or after October 1, 2012. After completion of the survey, or when ice and weather conditions dictate, the vessels would exit to the south, transiting through the Chukchi and Bering Seas. The
Polar Prince
may be used to perform an at-sea refueling (bunkering) operation to supply as much as 500 metric tons of Arctic diesel to the
Geo Arctic.
The
Polar Prince
would carry that fuel onboard at the start of the operation, and it would be transferred to the
Geo Arctic
if/when necessary. Depending on its own fuel consumption, the
Polar Prince
may then transit to Tuktoyuktuk, Canada to take on additional fuel for itself. Once the
Polar Prince
returns to the
Geo Arctic
the survey would continue. The entire refueling operation would therefore involve one fuel transfer and potentially one transit to and from Tuktoyuktuk. The refueling operation would likely take place in late October, at which time the
Geo Arctic
would likely be in the eastern or east-central Alaskan Beaufort Sea.

ION's geophysical survey has been designed and scheduled to minimize potential effects to marine mammals, bowhead whales in particular, and subsistence users. For mitigation and operational reasons, the survey area has been bisected by a line that runs from 70.5° N. 150.5° W. to 73° N. 148° W. (see Figure 1 of ION's IHA application). Weather and ice permitting, ION plans to begin survey operations east of the line described above (eastern survey area) and in offshore waters (>1,000 m [3,281 ft]) where bowheads are expected to be least abundant in early October. This operational plan is based on the fact that only ~2% of bowhead whales observed by Bureau of Ocean Energy Management's (BOEM) aerial surveys from 1979-2007 occurred in areas of water depth >1,000 m (3,281 ft) (MMS, 2010), and on average ~97% of bowheads have passed through the eastern U.S. Beaufort Sea by October 15 (Miller
et al.,
2002). The survey would then progress to shallower waters in the eastern survey area before moving to the western survey area in late October or early November 2012.

Ice conditions are expected to range from open water to 10/10 ice cover. However, the survey cannot take place in thick multi-year ice as both the icebreaker and seismic vessel must make continuous forward progress at 3-4 kts. In order for the survey to proceed, areas of high ice concentration can only consist of mostly newly forming juvenile first year ice or young first year ice less than 0.5 m (1.6 ft) thick. Sounds generated by the icebreaker and seismic vessel moving through these relatively light ice conditions are expected to be far below the high sound levels often attributed to icebreaking. These high sound levels (>200 dB re 1 µPa [rms]) have been recorded from icebreakers during backing and ramming operations in very heavy ice conditions and are created by cavitation of the propellers as the vessel is slowed by the ice or reverses direction (Erbe and Farmer, 1998; Roth and Schmidt, 2010).

Acoustic Sources

(1) Seismic Airgun Array

The seismic source used during the project would be an airgun array consisting of 28 Sercel G-gun airguns, of which 26 would be active and have a total discharge volume of 4,450 in
3
. The 28 airguns would be distributed in two sub-arrays with 14 airguns per sub-array. Individual airgun sizes range from 70 to 380 in
3
. Airguns would be operated at 2,000 psi. The seismic array and a single hydrophone streamer 4.5-9 km (2.8-5.6 mi) in length would be towed behind the
Geo Arctic.
Additional specifications of the airgun array are provided in Appendix B of ION's IHA application.

(2) Echo Sounders

Both vessels would operate industry standard echo sounder/fathometer instruments for continuous measurements of water depth while underway. These instruments are used by all large vessels to provide routine water depth information to the vessel crew. Navigation echo sounders send a single, narrowly focused, high frequency acoustic signal directly downward to the sea floor. The sound energy reflected off the sea floor returns to the vessel where it is detected by the instrument, and the depth is calculated and displayed to the user. Source levels of navigational echo sounders of this type are typically in the 180-200 dB re 1 µPA-m (Richardson
et al.,
1995a).

The
Geo Arctic
would use one navigational echo sounder during the project. The downward facing single-beam Simrad EA600 operates at frequencies ranging from 38 to 200 kHz with an output power of 100-2000 Watts. Pulse durations are between 0.064 and 4.096 milliseconds, and the pulse repetition frequency (PRF or ping rate) depends on the depth range. The highest PRF at shallow depths is about 40 pings per second. It can be used for water depths up to 4,000 m (13,123 ft) and provides up to 1 cm (0.4 in) resolution.

The
Polar Prince
would use one echo sounder, an ELAC LAZ-72. The LAZ-72 has an operating frequency of 30 kHz. The ping rate depends on the water depth and the fastest rate, which occurs in shallow depths, is about 5 pings per second.

Dates, Duration, and Region of Activity

The proposed geophysical survey would be conducted for ~76 days from approximately October 1 to December 15, 2012. Both the
Geo Arctic
and the
Polar Prince
would leave from Tuktoyaktuk, Canada, during late September and enter the Alaskan Beaufort Sea from Canadian waters. The survey area would be bounded approximately by 138° to 169° W. longitude and 70° to 73° N. latitude in water depths ranging from <20 to >3,500 m (66 to 11,483 ft) (see Figure 1 of ION's IHA application). For mitigation and operational reasons the survey area has been bisected by a line that runs from 70.5° N, 150.5° W to 73° N, 148° W. Weather and ice permitting, ION plans to begin survey operations east of the line (eastern survey area) in offshore waters (>1,000 m [3,281 ft]) where bowheads are expected to be least abundant in early October. The survey would then progress to shallower waters in the eastern survey area before moving to the west survey area in late October or early November. The vessels would depart the region to the south via the Chukchi and Bering Seas and arrive in Dutch Harbor in mid- to late December.

Description of Marine Mammals in the Area of the Specified Activity

The marine mammal species under NMFS jurisdiction most likely to occur in the seismic survey area include two cetacean species, beluga (
Delphinapterus leucas
) and bowhead whales (
Balaena mysticetus
), and two pinniped species, ringed (
Phoca hispida
) and bearded (
Erignathus barbatus
) seals. It is possible that some bowhead whales may be encountered as they migrate out of the area, particularly in the portion of the survey area where

water depths are <200 m (656 ft). Beluga whales are most likely to be encountered farther offshore than bowheads.

The ringed seal is the most abundant marine mammal in the proposed survey area. Although bearded seals typically migrate south in the fall, it is possible that small numbers of them may be present in the survey area. Most other marine mammal species have typically migrated south into the Chukchi and Bering Seas by the time this survey will take place. The polar bear is managed by the U.S. Fish and Wildlife Service (USFWS) and is not considered further in this proposed IHA notice.

Seven additional cetacean species have known occurrences within the proposed project area and some may occur in the area during the time of the proposed in-ice seismic survey: harbor porpoise (
Phocoena phocoena
); gray whale (
Eschrichtius robustus
); humpback whale (
Megaptera novaeangliae
); fin whale (
Balaenoptera physalus
); minke whale (
B. acutorostrata
); killer whale (
Orcinus orca
); and narwhal (
Monodon monoceros
). The gray whale occurs regularly in continental shelf waters along the Chukchi Sea coast in summer and to a lesser extent along the Beaufort Sea coast. Recent evidence from monitoring activities in the Chukchi and Beaufort Seas during industry seismic surveys suggests that the harbor porpoise and minke whale, which have been considered uncommon or rare in the Chukchi and Beaufort Seas, may be increasing in numbers in these areas (Funk
et al.,
2010). Additional pinniped species under NMFS jurisdiction that could be encountered during the proposed geophysical in-ice survey include spotted (
P. largha
) and ribbon seals (
Histriophoca fasciata
). Spotted seals are more abundant in the Chukchi Sea and occur in small numbers in the Beaufort Sea. The ribbon seal is uncommon in the Chukchi Sea, and there are few reported sightings in the Beaufort Sea.

Small numbers of killer whales have also been recorded during recent industry surveys, along with a few sightings of fin and humpback whales. The narwhal occurs in Canadian waters and occasionally in the Beaufort Sea but is rare there and not expected to be encountered. Each of these species (killer, fin, and humpback whales and narwhal) is uncommon or rare in the Beaufort Sea, particularly during early winter, and relatively few if any encounters with these species are expected during the time period of the proposed seismic program.

The bowhead, humpback, and fin whales are listed as “endangered” under the Endangered Species Act (ESA) and as depleted under the MMPA. Certain stocks or populations of gray and beluga whales and spotted seals are listed as endangered or proposed for listing under the ESA; however, none of those stocks or populations occur in the proposed activity area. Additionally, the ribbon seal is considered a “species of concern”, meaning that NMFS has some concerns regarding status and threats of this species, but for which insufficient information is available to indicate a need to list the species under the ESA. 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.

Based on the occurrence of marine mammal species in the proposed project area and the time of year in which the survey is proposed to be conducted, NMFS is proposing to authorize take by harassment for the following species: Beluga, bowhead, gray, and minke whales; harbor porpoise; and ringed, bearded, spotted, and ribbon seals.

ION's application contains information on the status, distribution, seasonal distribution, and abundance of each of the species under NMFS jurisdiction mentioned in this document. Please refer to the application for that information (see
ADDRESSES
). Additional information can also be found in the NMFS Stock Assessment Reports (SAR). The Alaska 2011 SAR is available at:
http://www.nmfs.noaa.gov/pr/pdfs/sars/ak2011.pdf.

Potential Effects of the Specified Activity on Marine Mammals

Operating active acoustic sources such as an airgun array, echo sounders, and icebreaking activities could potentially affect marine mammals.

Potential Effects of Airgun Sounds on Marine Mammals

The effects of sounds from airgun pulses might include one or more of the following: tolerance, masking of natural sounds, behavioral disturbance, and, at least in theory, temporary or permanent hearing impairment or non-auditory effects (Richardson
et al.,
1995). As outlined in previous NMFS documents, the effects of noise on marine mammals are highly variable, and can be categorized as follows (based on Richardson
et al.,
1995):

(1) Behavioral Disturbance

Marine mammals may behaviorally react when exposed to anthropogenic sound. These behavioral reactions are often shown as: changing durations of surfacing and dives; changing number of blows per surfacing; moving direction and/or speed; reduced/increased vocal activities; changing/cessation of certain behavioral activities (such as socializing or feeding); visible startle response or aggressive behavior (such as tail/fluke slapping or jaw clapping); avoidance of areas where noise sources are located; and/or flight responses (
e.g.,
pinnipeds flushing into water from haulouts or rookeries).

The biological significance of many behavioral disturbances is difficult to predict, especially if the detected disturbances appear minor. While many behavioral responses would not be expected to likely affect the fitness of an individual, other more severe behavioral modifications, especially in certain circumstances, could potentially have adverse affects on growth, survival, and/or reproduction. Some more potentially significant behavioral modifications include: drastic change in diving/surfacing patterns (such as those thought to be potentially associated with beaked whale stranding due to exposure to military mid-frequency tactical sonar) or longer-term habitat abandonment.

For example, at the Guerreo Negro Lagoon in Baja California, Mexico, which is one of the important breeding grounds for Pacific gray whales, shipping and dredging associated with a salt works may have induced gray whales to abandon the area through most of the 1960s (Bryant
et al.,
1984). After these activities stopped, the lagoon was reoccupied, first by single whales and later by cow-calf pairs.

The onset of behavioral disturbance from anthropogenic sound, which is difficult to predict, depends on both external factors (
e.g.,
characteristics of sound sources and their paths) and the receiving animals (hearing, motivation, experience, demography) (Southall
et al.
2007).

Currently NMFS uses 160 dB re 1 μPa (rms) received level for impulse noises (such as airgun pulses) as the threshold for the onset of Level B (behavioral) harassment.

In addition, behavioral disturbance is also expressed as the change in vocal activities of animals. For example, there is one recent summary report indicating that calling fin whales distributed in one part of the North Atlantic went

silent for an extended period starting soon after the onset of a seismic survey in the area (Clark and Gagnon, 2006). It is not clear from that preliminary paper whether the whales ceased calling because of masking, or whether this was a behavioral response not directly involving masking (
i.e.,
important biological signals for marine mammals being “masked” by anthropogenic sound; see below). Also, bowhead whales in the Beaufort Sea may decrease their call rates in response to seismic operations, although movement out of the area might also have contributed to the lower call detection rate (Blackwell
et al.,
2009a; 2009b). Some of the changes in marine mammal vocal communication are thought to be used to compensate for acoustic masking resulting from increased anthropogenic noise (see below). For example, blue whales are found to increase call rates when exposed to seismic survey noise in the St. Lawrence Estuary (Di Iorio and Clark, 2009). Researchers have noted North Atlantic right whales (
Eubalaena glacialis
) exposed to high shipping noise increase call frequency (Parks
et al.,
2007) and intensity (Parks
et al.,
2010), while some humpback whales respond to low-frequency active sonar playbacks by increasing song length (Miller
el al.,
2000). These behavioral responses could also have adverse effects on marine mammals.

Mysticete:
Baleen whales generally tend to avoid operating airguns, but avoidance radii are quite variable. Whales are often reported to show no overt reactions to airgun pulses at distances beyond a few kilometers, even though the airgun pulses remain well above ambient noise levels out to much longer distances (reviewed in Richardson
et al.,
1995; Gordon
et al.,
2004). However, studies done since the late 1990s of migrating humpback and migrating bowhead whales show reactions, including avoidance, that sometimes extend to greater distances than documented earlier. Therefore, it appears that behavioral disturbance can vary greatly depending on context and not just received levels alone. Avoidance distances often exceed the distances at which boat-based observers can see whales, so observations from the source vessel can be biased. Observations over broader areas may be needed to determine the range of potential effects of some large-source seismic surveys where effects on cetaceans may extend to considerable distances (Richardson
et al.,
1999; Moore and Angliss, 2006). Longer-range observations, when required, can sometimes be obtained via systematic aerial surveys or aircraft-based observations of behavior (
e.g.,
Richardson
et al.,
1986, 1999; Miller
et al.,
1999, 2005; Yazvenko
et al.,
2007a, 2007b) or by use of observers on one or more support vessels operating in coordination with the seismic vessel (
e.g.,
Smultea
et al.,
2004; Johnson
et al.,
2007). However, the presence of other vessels near the source vessel can, at least at times, reduce sightability of cetaceans from the source vessel (Beland
et al.,
2009), thus complicating interpretation of sighting data.

Some baleen whales show considerable tolerance of seismic pulses. However, when the pulses are strong enough, avoidance or other behavioral changes become evident. Because the responses become less obvious with diminishing received sound level, it has been difficult to determine the maximum distance (or minimum received sound level) at which reactions to seismic activity become evident and, hence, how many whales are affected.

Studies of gray, bowhead, and humpback whales have determined that received levels of pulses in the 160-170 dB re 1 μPa (rms) range seem to cause obvious avoidance behavior in a substantial fraction of the animals exposed (McCauley
et al.,
1998, 1999, 2000). In many areas, seismic pulses diminish to these levels at distances ranging from 4-15 km (2.5-9.3 mi) from the source. A substantial proportion of the baleen whales within such distances may show avoidance or other strong disturbance reactions to the operating airgun array. Some extreme examples include migrating bowhead whales avoiding considerably larger distances (20-30 km [12.4-18.6 mi]) at lower received sound levels (120-130 dB re 1 μPa (rms)) when exposed to airguns from seismic surveys. Also, even in cases where there is no conspicuous avoidance or change in activity upon exposure to sound pulses from distant seismic operations, there are sometimes subtle changes in behavior (
e.g.,
surfacing-respiration-dive cycles) that are only evident through detailed statistical analysis (
e.g.,
Richardson
et al.,
1986; Gailey
et al.,
2007).

Data on short-term reactions by cetaceans to impulsive noises are not necessarily indicative of long-term or biologically significant effects. It is not known whether impulsive sounds affect reproductive rates or distribution and habitat use in subsequent days or years. However, gray whales have continued to migrate annually along the west coast of North America despite intermittent seismic exploration (and much ship traffic) in that area for decades (Appendix A in Malme
et al.,
1984; Richardson
et al.,
1995), and there has been a substantial increase in the population over recent decades (Allen and Angliss, 2010). The western Pacific gray whale population did not seem affected by a seismic survey in its feeding ground during a prior year (Johnson
et al.,
2007). Similarly, bowhead whales have continued to travel to the eastern Beaufort Sea each summer despite seismic exploration in their summer and autumn range for many years (Richardson
et al.,
1987), and their numbers have increased notably during that same time period (Allen and Angliss, 2010). Bowheads also have been observed over periods of days or weeks in areas ensonified repeatedly by seismic pulses (Richardson
et al.,
1987; Harris
et al.,
2007). However, it is generally not known whether the same individual bowheads were involved in these repeated observations (within and between years) in strongly ensonified areas.

Odontocete:
Little systematic information is available about reactions of toothed whales to airgun pulses. Few studies similar to the more extensive baleen whale/seismic pulse work summarized above have been reported for toothed whales. However, there are recent systematic data on sperm whales (
e.g.,
Gordon
et al.,
2006; Madsen
et al.,
2006; Winsor and Mate, 2006; Jochens
et al.,
2008; Miller
et al.,
2009). There is also an increasing amount of information about responses of various odontocetes to seismic surveys based on monitoring studies (
e.g.,
Stone, 2003; Smultea
et al.,
2004; Moulton and Miller, 2005; Holst
et al.,
2006; Stone and Tasker, 2006; Potter
et al.,
2007; Hauser
et al.,
2008; Holst and Smultea, 2008; Weir, 2008; Barkaszi
et al.,
2009; Richardson
et al.,
2009).

Dolphins and porpoises are often seen by observers on active seismic vessels, occasionally at close distances (
e.g.,
bow riding). Marine mammal monitoring data during seismic surveys often show that animal detection rates drop during the firing of seismic airguns, indicating that animals may be avoiding the vicinity of the seismic area (Smultea
et al.,
2004; Holst
et al.,
2006; Hauser
et al.,
2008; Holst and Smultea, 2008; Richardson
et al.,
2009). Also, belugas summering in the Canadian Beaufort Sea showed larger-scale avoidance, tending to avoid waters out to 10-20 km (6.2-12.4 mi) from operating seismic vessels. In contrast, recent studies show little evidence of conspicuous reactions by sperm whales to airgun pulses, contrary to earlier indications (
e.g.,
Gordon
et al.,
2006; Stone and Tasker,

2006; Winsor and Mate, 2006; Jochens
et al.,
2008), except the lower buzz (echolocation signals) rates that were detected during exposure of airgun pulses (Miller
et al.,
2009).

There are almost no specific data on responses of beaked whales to seismic surveys, but it is likely that most if not all species show strong avoidance. There is increasing evidence that some beaked whales may strand after exposure to strong noise from tactical military mid-frequency sonars. Whether they ever do so in response to seismic survey noise is unknown. Northern bottlenose whales seem to continue to call when exposed to pulses from distant seismic vessels.

For delphinids, and possibly the Dall's porpoise, available data suggest that individuals may not react until sounds are ≥170 dB re 1 μPa (rms). With a medium-to-large airgun array, received levels typically diminish to 170 dB within 1-4 km (0.62-2.5 mi), whereas levels typically remain above 160 dB out to 4-15 km (
e.g.,
Tolstoy
et al.,
2009). Reaction distances for delphinids are more consistent at the typical 170 dB re 1 μPa (rms) distances. Stone (2003) and Stone and Tasker (2006) reported that all small odontocetes (including killer whales) observed during seismic surveys in UK waters remained significantly further from the source during periods of shooting on surveys with large volume airgun arrays than during periods without airgun shooting.

Due to their relatively higher frequency hearing ranges when compared to mysticetes, odontocetes may have stronger responses to mid- and high-frequency sources such as sub-bottom profilers, side scan sonar, and echo sounders than mysticetes (Richardson
et al.,
1995; Southall
et al.,
2007).

Pinnipeds:
Few studies of the reactions of pinnipeds to noise from open-water seismic exploration have been published (for review of the early literature, see Richardson
et al.,
1995). However, pinnipeds have been observed during a number of seismic monitoring studies. Monitoring in the Beaufort Sea during 1996-2002 provided a substantial amount of information on avoidance responses (or lack thereof) and associated behavior. Additional monitoring of that type has been done in the Beaufort and Chukchi Seas in 2006-2009. Pinnipeds exposed to seismic surveys have also been observed during seismic surveys along the U.S. west coast. Also, there are data on the reactions of pinnipeds to various other related types of impulsive sounds.

Early observations provided considerable evidence that pinnipeds are often quite tolerant of strong pulsed sounds. During seismic exploration off Nova Scotia, gray seals exposed to noise from airguns and linear explosive charges reportedly did not react strongly (J. Parsons in Greene
et al.,
1985). An airgun caused an initial startle reaction among South African fur seals but was ineffective in scaring them away from fishing gear. Pinnipeds in both water and air sometimes tolerate strong noise pulses from non-explosive and explosive scaring devices, especially if attracted to the area for feeding or reproduction (Mate and Harvey, 1987; Reeves
et al.,
1996). Thus, pinnipeds are expected to be tolerant of, or to habituate to, repeated underwater sounds from distant seismic sources, at least when the animals are strongly attracted to the area.

In summary, visual monitoring from seismic vessels has shown only slight (if any) avoidance of airguns by pinnipeds, and only slight (if any) changes in behavior. These studies show that many pinnipeds do not avoid the area within a few hundred meters of an operating airgun array. However, based on the studies with large sample size, or observations from a separate monitoring vessel, or radio telemetry, it is apparent that some phocid seals do show localized avoidance of operating airguns. The limited nature of this tendency for avoidance is a concern. It suggests that pinnipeds may not move away, or move very far away, before received levels of sound from an approaching seismic survey vessel approach those that may cause hearing impairment.

(2) Masking

Masking is the obscuring of sounds of interest by other sounds, often at similar frequencies. Chronic exposure to excessive, though not high-intensity, noise could cause masking at particular frequencies for marine mammals that utilize sound for vital biological functions. Masking can interfere with detection of acoustic signals such as communication calls, echolocation sounds, and environmental sounds important to marine mammals. Since marine mammals depend on acoustic cues for vital biological functions, such as orientation, communication, finding prey, and avoiding predators, marine mammals that experience severe (intensity and duration) acoustic masking could potentially suffer some adverse effects.

Masking occurs when noise and signals (that animal utilizes) overlap at both spectral and temporal scales. For the airgun noise generated from the proposed in-ice marine seismic survey, these are low frequency (under 1 kHz) pulses with extremely short durations (in the scale of milliseconds). Lower frequency man-made noises are more likely to affect detection of communication calls and other potentially important natural sounds such as surf and prey noise. There is little concern regarding masking due to the brief duration of these pulses and relatively longer silence between airgun shots (9-12 seconds) near the sound source. However, at long distances (over tens of kilometers away) in deep water, due to multipath propagation and reverberation, the durations of airgun pulses can be “stretched” to seconds with long decays (Madsen
et al.,
2006; Clark and Gagnon, 2006). Therefore it could affect communication signals used by low frequency mysticetes (
e.g.,
bowhead and gray whales) when they occur near the noise band and thus reduce the communication space of animals (
e.g.,
Clark
et al.,
2009a, 2009b) and affect their vocal behavior (
e.g.,
Foote
et al.,
2004; Holt
et al.,
2009). Further, in areas of shallow water, multipath propagation of airgun pulses could be more profound, thus affecting communication signals from marine mammals even at close distances. Average ambient noise in areas where received seismic noises are heard can be elevated. At long distances, however, the intensity of the noise is greatly reduced. Nevertheless, partial informational and energetic masking of different degrees could affect signal receiving in some marine mammals within the ensonified areas. Additional research is needed to further address these effects.

Although masking effects of pulsed sounds on marine mammal calls and other natural sounds are expected to be limited, there are few specific studies on this. Some whales continue calling in the presence of seismic pulses, and whale calls often can be heard between the seismic pulses (
e.g.,
Richardson
et al.,
1986; McDonald
et al.,
1995; Greene
et al.,
1999a, 1999b; Nieukirk
et al.,
2004; Smultea
et al.,
2004; Holst
et al.,
2005a, 2005b, 2006; Dunn and Hernandez, 2009).

Among the odontocetes, there has been one report that sperm whales ceased calling when exposed to pulses from a very distant seismic ship (Bowles
et al.,
1994). However, more recent studies of sperm whales found that they continued calling in the presence of seismic pulses (Madsen
et al.,
2002; Tyack
et al.,
2003; Smultea
et al.,
2004; Holst
et al.,
2006; Jochens
et al.,
2008). Madsen
et al.
(2006) noted that airgun

sounds would not be expected to mask sperm whale calls given the intermittent nature of airgun pulses. Dolphins and porpoises are also commonly heard calling while airguns are operating (Gordon
et al.,
2004; Smultea
et al.,
2004; Holst
et al.,
2005a, 2005b; Potter
et al.,
2007). Masking effects of seismic pulses are expected to be inconsequential in the case of the smaller odontocetes, given the intermittent nature of seismic pulses plus the fact that sounds important to them are predominantly at much higher frequencies than are the dominant components of airgun sounds.

Pinnipeds have best hearing sensitivity and/or produce most of their sounds at frequencies higher than the dominant components of airgun sound, but there is some overlap in the frequencies of the airgun pulses and the calls. However, the intermittent nature of airgun pulses presumably reduces the potential for masking.

Marine mammals are thought to be able to compensate for masking by adjusting their acoustic behavior, such as shifting call frequencies and increasing call volume and vocalization rates, as discussed earlier (
e.g.,
Miller
et al.,
2000; Parks
et al.,
2007; Di Iorio and Clark, 2009; Parks
et al.,
2010); the biological significance of these modifications is still unknown and would certainly depend on the duration of the masking event, the behavioral state of the animal, and the overall context of the exposure.

(3) Hearing Impairment

Marine mammals exposed to high intensity sound repeatedly or for prolonged periods can experience hearing threshold shift (TS), which is the loss of hearing sensitivity at certain frequency ranges (Kastak
et al.,
1999; Schlundt
et al.,
2000; Finneran
et al.,
2002; 2005). TS can be permanent (PTS), in which case the loss of hearing sensitivity is unrecoverable, or temporary (TTS), in which case the animal's hearing threshold will recover over time (Southall
et al.,
2007). Marine mammals that experience TTS or PTS will have reduced sensitivity at the frequency band of the TS, which may affect their capability of communication, orientation, or prey detection. The degree of TS depends on the intensity of the received levels the animal is exposed to, and the frequency at which TS occurs depends on the frequency of the received sound. It has been shown that in most cases, TS occurs at the frequencies approximately one-octave above that of the received sound. Repeated sound exposure that leads to TTS could cause PTS. For transient sounds, the sound level necessary to cause TTS is inversely related to the duration of the sound.

TTS

TTS is the mildest form of hearing impairment that can occur during exposure to a strong sound (Kryter, 1985). While experiencing TTS, the hearing threshold rises, and a sound must be stronger in order to be heard. It is a temporary phenomenon, and (especially when mild) is not considered to represent physical damage or “injury” (Southall
et al.,
2007). Rather, the onset of TTS is an indicator that, if the animal is exposed to higher levels of that sound, physical damage is ultimately a possibility.

The magnitude of TTS depends on the level and duration of noise exposure, and to some degree on frequency, among other considerations (Kryter, 1985; Richardson
et al.,
1995; Southall
et al.,
2007). For sound exposures at or somewhat above the TTS threshold, hearing sensitivity recovers rapidly after exposure to the noise ends. In terrestrial mammals, TTS can last from minutes or hours to (in cases of strong TTS) days. Only a few data have been obtained on sound levels and durations necessary to elicit mild TTS in marine mammals (none in mysticetes), and none of the published data concern TTS elicited by exposure to multiple pulses of sound during operational seismic surveys (Southall
et al.,
2007).

For toothed whales, experiments on a bottlenose dolphin (
Tursiops truncatus
) and beluga whale showed that exposure to a single watergun impulse at a received level of 207 kPa (or 30 psi) peak-to-peak (p-p), which is equivalent to 228 dB re 1 μPa (p-p), resulted in a 7 and 6 dB TTS in the beluga whale at 0.4 and 30 kHz, respectively. Thresholds returned to within 2 dB of the pre-exposure level within 4 minutes of the exposure (Finneran
et al.,
2002). No TTS was observed in the bottlenose dolphin.

Finneran
et al.
(2005) further examined the effects of tone duration on TTS in bottlenose dolphins. Bottlenose dolphins were exposed to 3 kHz tones (non-impulsive) for periods of 1, 2, 4 or 8 seconds (s), with hearing tested at 4.5 kHz. For 1-s exposures, TTS occurred with sound exposure levels (SELs) of 197 dB, and for exposures >1 s, SEL >195 dB resulted in TTS (SEL is equivalent to energy flux, in dB re 1 μPa
2
-s). At an SEL of 195 dB, the mean TTS (4 min after exposure) was 2.8 dB. Finneran
et al.
(2005) suggested that an SEL of 195 dB is the likely threshold for the onset of TTS in dolphins and belugas exposed to tones of durations 1-8 s (
i.e.,
TTS onset occurs at a near-constant SEL, independent of exposure duration). That implies that, at least for non-impulsive tones, a doubling of exposure time results in a 3 dB lower TTS threshold.

However, the assumption that, in marine mammals, the occurrence and magnitude of TTS is a function of cumulative acoustic energy (SEL) is probably an oversimplification. Kastak
et al.
(2005) reported preliminary evidence from pinnipeds that, for prolonged non-impulse noise, higher SELs were required to elicit a given TTS if exposure duration was short than if it was longer,
i.e.,
the results were not fully consistent with an equal-energy model to predict TTS onset. Mooney
et al.
(2009a) showed this in a bottlenose dolphin exposed to octave-band non-impulse noise ranging from 4 to 8 kHz at SPLs of 130 to 178 dB re 1 μPa for periods of 1.88 to 30 minutes (min). Higher SELs were required to induce a given TTS if exposure duration was short than if it was longer. Exposure of the aforementioned bottlenose dolphin to a sequence of brief sonar signals showed that, with those brief (but non-impulse) sounds, the received energy (SEL) necessary to elicit TTS was higher than was the case with exposure to the more prolonged octave-band noise (Mooney
et al.,
2009b). Those authors concluded that, when using (non-impulse) acoustic signals of duration ~0.5 s, SEL must be at least 210-214 dB re 1 μPa
2
-s to induce TTS in the bottlenose dolphin. The most recent studies conducted by Finneran
et al.
(2010a, 2010b) also support the notion that exposure duration has a more significant influence compared to sound pressure level (SPL) as the duration increases, and that TTS growth data are better represented as functions of SPL and duration rather than SEL alone (Finneran
et al.,
2010a, 2010b). In addition, Finneran
et al.
(2010b) conclude that when animals are exposed to intermittent noises, there is recovery of hearing during the quiet intervals between exposures through the accumulation of TTS across multiple exposures. Such findings suggest that when exposed to multiple seismic pulses, partial hearing recovery also occurs during the seismic pulse intervals.

For baleen whales, there are no data, direct or indirect, on levels or properties of sound that are required to induce TTS. The frequencies to which baleen whales are most sensitive are lower than those to which odontocetes are most sensitive, and natural ambient noise levels at those low frequencies tend to be higher (Urick, 1983). As a result,

auditory thresholds of baleen whales within their frequency band of best hearing are believed to be higher (less sensitive) than are those of odontocetes at their best frequencies (Clark and Ellison, 2004). From this, it is suspected that received levels causing TTS onset may also be higher in baleen whales. However, no cases of TTS are expected given the size of the airguns proposed to be used and the strong likelihood that baleen whales (especially migrating bowheads) would avoid the approaching airguns (or vessel) before being exposed to levels high enough for there to be any possibility of TTS.

In pinnipeds, TTS thresholds associated with exposure to brief pulses (single or multiple) of underwater sound have not been measured. Initial evidence from prolonged exposures suggested that some pinnipeds may incur TTS at somewhat lower received levels than do small odontocetes exposed for similar durations (Kastak
et al.,
1999; 2005). However, more recent indications are that TTS onset in the most sensitive pinniped species studied (harbor seal, which is closely related to the ringed seal) may occur at a similar SEL as in odontocetes (Kastak
et al.,
2004).

Most cetaceans show some degree of avoidance of seismic vessels operating an airgun array (see above). It is unlikely that these cetaceans would be exposed to airgun pulses at a sufficiently high enough level for a sufficiently long enough period to cause more than mild TTS, given the relative movement of the vessel and the marine mammal. TTS would be more likely in any odontocetes that bow- or wake-ride or otherwise linger near the airguns. However, while bow- or wake-riding, odontocetes would be at the surface and thus not exposed to strong sound pulses given the pressure release and Lloyd Mirror effects at the surface. But if bow- or wake-riding animals were to dive intermittently near airguns, they could be exposed to strong sound pulses, possibly repeatedly.

If some cetaceans did incur mild or moderate TTS (a Level B harassment) through exposure to airgun sounds in this manner, this would very likely be a temporary and reversible phenomenon. However, even a temporary reduction in hearing sensitivity could be deleterious in the event that, during that period of reduced sensitivity, a marine mammal needed its full hearing sensitivity to detect approaching predators, or for some other reason.

Some pinnipeds show avoidance reactions to airguns, but their avoidance reactions are generally not as strong or consistent as those of cetaceans. Pinnipeds occasionally seem to be attracted to operating seismic vessels. There are no specific data on TTS thresholds of pinnipeds exposed to single or multiple low-frequency pulses. However, given the indirect indications of a lower TTS threshold for the harbor seal than for odontocetes exposed to impulse sound (see above), it is possible that some pinnipeds close to a large airgun array could incur TTS.

NMFS typically includes mitigation requirements to ensure that cetaceans and pinnipeds are not exposed to pulsed underwater noise at received levels exceeding, respectively, 180 and 190 dB re 1 μPa (rms). The 180/190 dB acoustic criteria were taken from recommendations by an expert panel of the High Energy Seismic Survey (HESS) Team that performed an assessment on noise impacts by seismic airguns to marine mammals in 1997, although the HESS Team recommended a 180-dB limit for pinnipeds in California (HESS, 1999). The 180 and 190 dB re 1 μPa (rms) levels have not been considered to be the levels above which TTS might occur. Rather, they were the received levels above which, in the view of a panel of bioacoustics specialists convened by NMFS before TTS measurements for marine mammals started to become available, one could not be certain that there would be no injurious effects, auditory or otherwise, to marine mammals. As summarized above, data that are now available imply that TTS is unlikely to occur in various odontocetes (and probably mysticetes as well) unless they are exposed to a sequence of several airgun pulses stronger than 180 dB re 1 μPa (rms). On the other hand, for the harbor seal, harbor porpoise, and perhaps some other species, TTS may occur upon exposure to one or more airgun pulses whose received level equals the NMFS “do not exceed” value of 180 dB re 1 μPa (rms). That criterion corresponds to a single-pulse SEL of 175-180 dB re 1 μPa
2
-s in typical conditions, whereas TTS is suspected to be possible in harbor seals and harbor porpoises with a cumulative SEL of ~171 and ~164 dB re 1 μPa
2
-s, respectively.

It has been shown that most large whales and many smaller odontocetes (especially the harbor porpoise) show at least localized avoidance of ships and/or seismic operations. Even when avoidance is limited to the area within a few hundred meters of an airgun array, that should usually be sufficient to avoid TTS based on what is currently known about thresholds for TTS onset in cetaceans. In addition, ramping up airgun arrays, which is standard operational protocol for many seismic operators, may allow cetaceans near the airguns at the time of startup (if the sounds are aversive) to move away from the seismic source and to avoid being exposed to the full acoustic output of the airgun array. Thus, most baleen whales likely will not be exposed to high levels of airgun sounds provided the ramp-up procedure is applied. Likewise, many odontocetes close to the trackline are likely to move away before the sounds from an approaching seismic vessel become sufficiently strong for there to be any potential for TTS or other hearing impairment. Hence, there is little potential for baleen whales or odontocetes that show avoidance of ships or airguns to be close enough to an airgun array to experience TTS. Nevertheless, even if marine mammals were to experience TTS, the magnitude of the TTS is expected to be mild and brief, only in a few decibels for minutes.

PTS

When PTS occurs, there is physical damage to the sound receptors in the ear. In some cases, there can be total or partial deafness, whereas in other cases, the animal has an impaired ability to hear sounds in specific frequency ranges (Kryter, 1985). Physical damage to a mammal's hearing apparatus can occur if it is exposed to sound impulses that have very high peak pressures, especially if they have very short rise times. (Rise time is the interval required for sound pressure to increase from the baseline pressure to peak pressure.)

There is no specific evidence that exposure to pulses of airgun sound can cause PTS in any marine mammal, even with large arrays of airguns. However, given the likelihood that some mammals close to an airgun array might incur at least mild TTS (see above), there has been further speculation about the possibility that some individuals occurring very close to airguns might incur PTS (
e.g.,
Richardson
et al.,
1995; Gedamke
et al.,
2008). Single or occasional occurrences of mild TTS are not indicative of permanent auditory damage, but repeated or (in some cases) single exposures to a level well above that causing TTS onset might elicit PTS.

Relationships between TTS and PTS thresholds have not been studied in marine mammals but are assumed to be similar to those in humans and other terrestrial mammals (Southall
et al.,
2007). Based on data from terrestrial mammals, a precautionary assumption is that the PTS threshold for impulse sounds (such as airgun pulses as received close to the source) is at least 6 dB higher than the TTS threshold on a peak-pressure basis and probably >6

dB higher (Southall
et al.,
2007). The low-to-moderate levels of TTS that have been induced in captive odontocetes and pinnipeds during controlled studies of TTS have been confirmed to be temporary, with no measurable residual PTS (Kastak
et al.,
1999; Schlundt
et al.,
2000; Finneran
et al.,
2002; 2005; Nachtigall
et al.,
2003; 2004). However, very prolonged exposure to sound strong enough to elicit TTS, or shorter-term exposure to sound levels well above the TTS threshold, can cause PTS, at least in terrestrial mammals (Kryter 1985). In terrestrial mammals, the received sound level from a single non-impulsive sound exposure must be far above the TTS threshold for any risk of permanent hearing damage (Kryter, 1994; Richardson
et al.,
1995; Southall
et al.,
2007). However, there is special concern about strong sounds whose pulses have very rapid rise times. In terrestrial mammals, there are situations when pulses with rapid rise times (
e.g.,
from explosions) can result in PTS even though their peak levels are only a few dB higher than the level causing slight TTS. The rise time of airgun pulses is fast but not as fast as that of an explosion.

Some factors that contribute to onset of PTS, at least in terrestrial mammals, are as follows:

• Exposure to a single very intense sound,

• Fast rise time from baseline to peak pressure,

• Repetitive exposure to intense sounds that individually cause TTS but not PTS, and

• Recurrent ear infections or (in captive animals) exposure to certain drugs.

Cavanagh (2000) reviewed the thresholds used to define TTS and PTS. Based on this review and SACLANT (1998), it is reasonable to assume that PTS might occur at a received sound level 20 dB or more above that inducing mild TTS. However, for PTS to occur at a received level only 20 dB above the TTS threshold, the animal probably would have to be exposed to a strong sound for an extended period or to a strong sound with a rather rapid rise time.

More recently, Southall
et al.
(2007) estimated that received levels would need to exceed the TTS threshold by at least 15 dB, on an SEL basis, for there to be risk of PTS. Thus, for cetaceans exposed to a sequence of sound pulses, they estimate that the PTS threshold might be an M-weighted SEL (for the sequence of received pulses) of ~198 dB re 1 μPa
2
-s. Additional assumptions had to be made to derive a corresponding estimate for pinnipeds, as the only available data on TTS-thresholds in pinnipeds pertained to non-impulse sound (see above). Southall
et al.
(2007) estimated that the PTS threshold could be a cumulative SEL of ~186 dB re 1 μPa
2
-s in the case of a harbor seal exposed to impulse sound. The PTS threshold for the California sea lion and northern elephant seal would probably be higher given the higher TTS thresholds in those species. Southall
et al.
(2007) also note that, regardless of the SEL, there is concern about the possibility of PTS if a cetacean or pinniped received one or more pulses with peak pressure exceeding 230 or 218 dB re 1 μPa, respectively. Thus, PTS might be expected upon exposure of cetaceans to either SEL ≥198 dB re 1 μPa
2
-s or peak pressure ≥230 dB re 1 μPa. Corresponding proposed dual criteria for pinnipeds (at least harbor seals) are ≥186 dB SEL and ≥ 218 dB peak pressure (Southall
et al.,
2007). These estimates are all first approximations, given the limited underlying data, assumptions, species differences, and evidence that the “equal energy” model may not be entirely correct.

Sound impulse duration, peak amplitude, rise time, number of pulses, and inter-pulse interval are the main factors thought to determine the onset and extent of PTS. Ketten (1994) has noted that the criteria for differentiating the sound pressure levels that result in PTS (or TTS) are location and species specific. PTS effects may also be influenced strongly by the health of the receiver's ear.

As described above for TTS, in estimating the amount of sound energy required to elicit the onset of TTS (and PTS), it is assumed that the auditory effect of a given cumulative SEL from a series of pulses is the same as if that amount of sound energy were received as a single strong sound. There are no data from marine mammals concerning the occurrence or magnitude of a potential partial recovery effect between pulses. In deriving the estimates of PTS (and TTS) thresholds quoted here, Southall
et al.
(2007) made the precautionary assumption that no recovery would occur between pulses.

It is unlikely that an odontocete would remain close enough to a large airgun array for a sufficiently long enough period to incur PTS. There is some concern about bow-riding odontocetes, but for animals at or near the surface, auditory effects are reduced by Lloyd's mirror and surface release effects. The presence of the vessel between the airgun array and bow-riding odontocetes could also, in some but probably not all cases, reduce the levels received by bow-riding animals (
e.g.,
Gabriele and Kipple, 2009). The TTS (and thus PTS) thresholds of baleen whales are unknown but, as an interim measure, assumed to be no lower than those of odontocetes. Also, baleen whales generally avoid the immediate area around operating seismic vessels, so it is unlikely that a baleen whale could incur PTS from exposure to airgun pulses. The TTS (and thus PTS) thresholds of some pinnipeds (
e.g.,
harbor seal) as well as the harbor porpoise may be lower (Kastak
et al.,
2005; Southall
et al.,
2007; Lucke
et al.,
2009). If so, TTS and potentially PTS may extend to a somewhat greater distance for those animals. Again, Lloyd's mirror and surface release effects will ameliorate the effects for animals at or near the surface. NMFS considers PTS to be a Level A harassment.

(4) Non-Auditory Physical Effects

Non-auditory physical effects might occur in marine mammals exposed to strong underwater pulsed sound. Possible types of non-auditory physiological effects or injuries that theoretically might occur in mammals close to a strong sound source include neurological effects, bubble formation, and other types of organ or tissue damage. Some marine mammal species (
i.e.,
beaked whales) may be especially susceptible to injury and/or stranding when exposed to intense sounds. However, there is no definitive evidence that any of these effects occur even for marine mammals in close proximity to large arrays of airguns, and beaked whales do not occur in the proposed project area. In addition, marine mammals that show behavioral avoidance of seismic vessels, including most baleen whales, some odontocetes (including belugas), and some pinnipeds, are especially unlikely to incur non-auditory impairment or other physical effects.

Therefore, it is unlikely that such effects would occur during ION's proposed in-ice seismic surveys given the brief duration of exposure and the planned monitoring and mitigation measures described later in this document.

Additional non-auditory effects include elevated levels of stress response (Wright
et al.,
2007; Wright and Highfill, 2007). Although not many studies have been done on noise-induced stress in marine mammals, extrapolation of information regarding stress responses in other species seems applicable because the responses are highly consistent among all species in which they have been examined to date

(Wright
et al.,
2007). Therefore, it is reasonable to conclude that noise acts as a stressor to marine mammals. Furthermore, given that marine mammals will likely respond in a manner consistent with other species studied, repeated and prolonged exposures to stressors (including or induced by noise) could potentially be problematic for marine mammals of all ages. Wright
et al.
(2007) state that a range of issues may arise from an extended stress response including, but not limited to, suppression of reproduction (physiologically and behaviorally), accelerated aging and sickness-like symptoms. However, as mentioned above, ION's proposed activity is not expected to result in these severe effects due to the nature of the potential sound exposure.

(5) Stranding and Mortality

Marine mammals close to underwater detonations can be killed or severely injured, and the auditory organs are especially susceptible to injury (Ketten
et al.,
1993; Ketten, 1995). Airgun pulses are less energetic, and their peak amplitudes have slower rise times, while stranding and mortality events would include other energy sources (acoustical or shock wave) far beyond just seismic airguns. To date, there is no evidence that serious injury, death, or stranding by marine mammals can occur from exposure to airgun pulses, even in the case of large airgun arrays.

However, in past IHA notices for seismic surveys, commenters have referenced two stranding events allegedly associated with seismic activities, one off Baja California and a second off Brazil. NMFS has addressed this concern several times, and, without new information, does not deem the issue to warrant further discussion. For information relevant to strandings of marine mammals, readers are encouraged to review NMFS' response to comments on this matter found in 69 FR 74906 (December 14, 2004), 71 FR 43112 (July 31, 2006), 71 FR 50027 (August 24, 2006), and 71 FR 49418 (August 23, 2006).

It should be noted that strandings related to sound exposure have not been recorded for marine mammal species in the Beaufort Sea. NMFS notes that in the Beaufort Sea, aerial surveys have been conducted by the Minerals Management Service (now BOEM) and industry during periods of industrial activity (and by BOEM during times with no activity). No strandings or marine mammals in distress have been observed during these surveys, and none have been reported by North Slope Borough inhabitants. In addition, there are very few instances that seismic surveys in general have been linked to marine mammal strandings, other than those mentioned above. As a result, NMFS does not expect any marine mammals will incur serious injury or mortality in the Arctic Ocean or strand as a result of the proposed seismic survey.

Potential Effects From Echo Sounders on Marine Mammals

Three types of echo sounders have been proposed for ION's 2012 in-ice seismic survey in the Beaufort and Chukchi Seas. In general, the potential effects of this equipment on marine mammals can be expected to be similar to those from the airgun, except that the sounds from these sources are at much higher frequencies than those from airguns, and thus may have more potential to affect mid- and high-frequency hearing odontocetes and pinnipeds than mysticetes, who are thought to be more sensitive to low-frequency sounds. Therefore, it is possible that the onset of hearing impairment to odontocetes and pinnipeds that are exposed to mid- or high-frequency sources could be lower, or the growth of TTS and/or PTS could be faster than the earlier empirical measurements using the watergun source (Finneran
et al.,
2002) or 3 kHz tones (Finneran
et al.,
2005). However, the magnitude of the impacts is expected to be less due to the lower intensity of the sound from echo sounders when compared to seismic airguns. Because of the higher frequencies of the echo sounder signals, the propagation ranges of acoustic signals are also much shorter than those from the airgun array. Since these echo sounders will be operating during the seismic survey, no additional takes of marine mammals would be considered as take estimates would be calculated from ensonified zones from seismic airguns. In addition, due to the fact that the operating frequencies of some of this equipment (
e.g.,
Skipper GDS102 that operates at frequencies above 200 kHz) are above the hearing ranges of marine mammals, use of the equipment is not expected to cause any take of marine mammals. Furthermore, the beam patterns of the echo sounders are directed downward and are narrow, so any marine mammals that encounter the echo sounders at close range are unlikely to be subjected to repeated pulses.

Potential Effects From Icebreaking on Marine Mammals

(1) Noise Source Levels From Icebreaking

Most sounds generated by icebreaking activities are caused by cavitation of the propellers. Propeller cavitation and resulting sounds tend to be greatest when a vessel is moving astern or when its forward progress has been stopped by heavy ice during ramming. When making continuous forward progress through ice, more power is required than when traveling through open water. The greater the resistance, the greater the propeller cavitation and resulting sounds, although they are typically less strong during continuous forward progress than during backing and ramming in heavy ice.

Measurements of the
Robert Lemur
pushing and breaking ice in the Beaufort Sea in 1986 resulted in an estimated broadband source level of 193 dB re 1 μPa @ 1 m (Richardson
et al.,
1995). Ice conditions were not described in detail, but at that time of year (in September), ice is not typically forming, so the ice pans that were encountered were likely composed of second year ice or multi-year ice.

The broadband source levels of three different vessels pushing on or breaking ice during drilling activities in the U.S. Beaufort Sea in 1993 were 181-183, 184, and 174 dB re 1 μPa @ 1 m (Hall
et al.,
1994). Similar to the above, ice conditions in mid-August when these recordings were made were likely to have been thick first year (sea ice does not reach “second year” status until September 1), second year, or multi-year ice.

The strongest sounds produced by an icebreaker backing and ramming an ice ridge were measured at 203 dB re 1 μPa @ 1 m at the point when the propellers were still turning at full speed ahead, but the vessel had come to a stop when it failed to break the ice ridge (Erbe and Farmer, 1998). A similar maximum source level (200 dB re 1 μPa @ 1m) was reported during backing and ramming activities by the U.S. Coast Guard Cutter
Healy
as measured by a sonobuoy deployed from that vessel in 2009 (Roth and Schmidt, 2010).

Roth and Schmidt (2010) describe three very recent “case studies” of
Healy
breaking ice in the high Arctic. Ice type is not described, but given the date, location, and pictures provided the ice is clearly not first year ice and instead likely second year or multi-year ice. The first case study provides an example of the
Healy
traveling through 7-9/10ths ice and then entering open-water. Average source levels in ice were

estimated to be ~185 dB while average source levels in open-water were estimated between 175-180 dB. The second case study is an example of backing and ramming in 8/10ths ice. Maximum source levels reached 191-195 dB. The third case study is another example of backing and ramming, this time in 9/10ths ice, where maximum source levels reached 200 dB.

None of these examples apply very well to ice conditions likely to be encountered during ION's proposed October-December survey. The ice regimes to be encountered along the Alaskan Coast in the proposed survey area during the proposed survey period will vary considerably from predominantly or entirely open water in early October to being predominantly new, first year ice in November. The survey work will take advantage of such variations to complete the more difficult lines when the ice conditions are favorable for that work.

This project will involve two ships working as one when in or near sea ice. In this mode, the icebreaker (
Polar Prince
) would escort the geophysical survey ship (
Geo Arctic
). As both ships must move continuously at near survey speed throughout this escort, it is essential that this work is carried out in ice conditions where the icebreaker is not obliged to undertake ramming operations.

ION used the Arctic Ice Regime Shipping System (AIRSS) to aid in their determination concerning suitable conditions for the survey. This system allows the Arctic Mariner/Ice Master to calculate the “toughness” of a particular ice regime. As a “rule of thumb,” seismic is normally considered achievable in ice where the calculation indicates navigation can safely be undertaken by the ice strengthened (Ice Class A1A, type A) geophysical ship, operating independently. ION states that it will take a conservative approach by using a heavy escort icebreaker. This means the icebreaker is normally working well below maximum power but does have a huge propulsive power capacity held in reserve in case ridges or other such ice features are encountered. Thus the icebreaker is breaking ice at a fraction of its maximum or rated capacity.

Compared to the aggressive icebreaking involved in the examples above, the icebreaking for in-ice seismic surveys is of a much different and considerably lower order. In most ice regimes expected to be encountered during ION's proposed survey, the
Polar Prince
will have about 5,123 HP available for propulsion, which is far less than the power of the heavy icebreaker
Healy
reported in Roth and Schmidt (2010). There would still be a direct correlation between icebreaking effort and icebreaking noise, although there are likely also many other variables such as thermal gradient, stage of ice development, speed of impact, propulsion system characteristics, hull and bow form, etc., that may differentiate the sounds produced during the proposed survey. In the examples provided in Roth and Schmidt (2010), the
Healy
appears to be backing and ramming in heavy multiyear ice (based on our interpretation of the pictures). Such conditions are beyond the allowable operational conditions of this project, and, if such conditions were encountered, the Type A geophysical ship could not follow such an ice-encumbered track of multiyear ice.

It should also be noted that the
Healy
was operating at maximum capacity during the measurements reported in Roth and Schmidt (2010), while during ice-seismic the escorting icebreaker rarely operates in excess of 50% capacity. Thus, accounting for the disparity in the horsepower ratings of the
Polar Prince
vs. the
Healy,
the
Polar Prince
is rendering an output, in terms of horsepower expended, of <25% each of that of the
Healy
during the reported measurements.

Based on available information regarding sounds produced by icebreaking in various ice regimes and the expected ice conditions during the proposed survey, NMFS determined that vessel sounds generated during ice breaking are likely to have source levels between 175 and 185 dB re 1 µPa-m.

(2) Impacts of Icebreaking Noise on Marine Mammals

Limited information is available about the effects of icebreaking ships on most species of marine mammals. Concerns have arisen in the past due to proposals (which were never realized) to conduct shipping of oil and gas in the Arctic via large icebreakers (Peterson, 1981). In the past, smaller icebreaking ships were used by the oil and gas industry in the Beaufort and Chukchi Seas to extend the offshore drilling period in support of offshore drilling, and several icebreakers or strengthened cargo ships have been used in the Russian northern sea route, as well as elsewhere in the Arctic and Antarctic (Armstrong, 1984; Barr and Wilson, 1985; Brigham, 1985).

The primary concern regarding icebreaking activities involves the production of intense underwater sound (Richardson
et al.,
1995). Estimated source levels of the ice-breaking cargo vessel
MV Arctic
may be detectable by seals under fast ice at distances up to 20-35 km (12.4-21.8 mi) (Davis and Malme, 1997). However, icebreaking activities may also have non-acoustic effects, such as the potential for causing injury, ice entrapment of animals that follow the ship, and disruption of ice habitat (reviewed in Richardson
et al.,
1989), though, as described below, these impacts are not anticipated during this action. The species of marine mammals that may be present and the nature of icebreaker activities are strongly influenced by ice type. Some species are more common in loose ice near the margins of heavy pack ice while others appear to prefer heavy pack ice. Propeller cavitation noise of icebreaking ships in loose ice is expected to be much lower than in areas of heavier pack ice or thick landfast ice where ship speed will be reduced, power levels will be higher, and there will be greater propeller cavitation and back-ramming (Richardson
et al.,
1995).

Beluga Whales
—Erbe and Farmer (1998) measured masked hearing thresholds of a captive beluga whale. They reported that the recording of a Canadian Coast Guard ship,
Henry Larsen,
ramming ice in the Beaufort Sea, masked recordings of beluga vocalizations at a noise-to-signal pressure ratio of 18 dB. That occurred when the noise pressure level was eight times as high as the call. In linear units, the ramming noise was 8 times as strong as the call (Erbe and Farmer, 1998). A similar study using a software model to estimate the zones of impact around icebreakers affecting beluga whales in the Beaufort Sea predicted that masking of beluga communication signals by ramming noise from an icebreaker could occur within 40-71 km (25-44 mi), depending on the location. However, Arctic beluga whales have shown avoidance of icebreakers when first detected (Erbe and Farmer, 2000), so individuals are unlikely to get close enough for effects such as masking to occur. In addition, vocal behavior of beluga whales in the St. Lawrence River in the presence of a ferry and a small motorboat have shown that belugas can change the types of calls they use, as well as shift the mean call frequency up during noise exposure (Lesage
et al.,
1999). Therefore, it is possible that beluga whales in the Beaufort and Chukchi Seas may also have some mechanism that would allow them to adapt to ambient noise due to icebreaking activities.

In 1991 and 1994 in the Alaskan Beaufort Sea, Richardson
et al.
(1995b) recorded reactions of beluga and bowhead whales to playbacks of underwater propeller cavitation noise

from the icebreaker
Robert Lemeur
operating in heavy ice. Migrating belugas were observed close to the playback projectors on three dates, but interpretable data were only collected on 17 groups for two of these occasions. A minimum of six groups apparently altered their path in response to the playback, but whales approached within a few hundred (and occasionally tens of) meters before exhibiting a response. Icebreaker sounds were estimated at 78-84 dB re 1μPa in the 1/3-octave band centered at 5,000 Hz, or 8-14 dB above ambient sound levels in that band, for the six groups that reacted. The authors estimated that reactions at this level would be estimated to occur at distances of approximately 10 km (6.2 mi) from an operating icebreaker.

Beluga whales are expected to avoid icebreaking vessels at distances of approximately 10 km (6.2 mi). The impacts of icebreaking associated with the seismic program on the behavior of belugas are expected to be temporary, lasting only as long as the activity is on-going, and would have a negligible impact on the species or stock.

Bowhead Whales
—In 1991 and 1994 in the Alaskan Beaufort Sea, Richardson
et al.
(1995b) recorded reactions of beluga and bowhead whales to playbacks of underwater propeller cavitation noise from the icebreaker
Robert Lemeur
operating in heavy ice. Bowhead whales migrating in the nearshore appeared to tolerate exposure to projected icebreaker sounds at received levels up to 20 dB or more above ambient noise levels. However, some bowheads appeared to divert their paths to remain further away from the projected sounds, particularly when exposed to levels >20 dB above ambient. Turning frequency, surface duration, number of blows per surfacing, and two multivariate indices of behavior were significantly correlated with the signal-to-noise ratio >20 dB (and as low as 10 dB for turning frequency). The authors suggested that bowheads may commonly react to icebreakers at distances up to 10-50 km (6.2-31 mi), but note that reactions were highly dependent on several variables not controlled in the study.

There are few other studies on the reactions of baleen whales to icebreaking activities. During fall 1992, migrating bowhead whales apparently avoided (by at least 25 km [15.5 mi]) a drill site that was supported almost daily by intensive icebreaking activity in the Alaskan Beaufort Sea (Brewer
et al.,
1993). However, bowheads also avoided a nearby drill site in the fall of another year that had little icebreaking support (LGL and Greenridge, 1987). Thus, level of contribution from icebreaking, ice concentration, and drilling noise resulting in bowhead responses is unknown.

Bowhead whales are expected to avoid vessels that are underway, including icebreakers. The impacts of icebreaking on the behavior of bowheads are likely to occur only if bowheads are still in the western portion of the proposed study area, although most bowheads will likely have passed through the survey area prior to the start of survey activities. The effects of icebreaking activities on bowhead whales are expected to be minor and short-term.

Pinnipeds
— Reactions of walruses to icebreakers are described more thoroughly in the available literature than are reactions by other pinnipeds. When comparing the reaction distances of walrus to icebreaking ships vs. other ships traveling in open water, Fay
et al.
(1984) found that walrus reacted at longer distances to icebreakers. They were aware of the icebreaker when it was >2 km (1.2 mi) away, and females with pups entered the water and swam away when the ship was ~1 km (0.62 mi) away while adult males did so at distances of 0.1 to 0.3 km (0.1 to 0.2 mi). However, it was also noted that some walruses, ringed seals, and bearded seals also scrambled onto ice when an icebreaker was oriented toward them.

In another study of 202 walrus groups observed on ice floes during icebreaking activities, 32% dove into the water, and 6% became alert while on the ice (Brueggeman
et al.,
1990, 1991, 1992). Concurrent aerial surveys indicated that walruses hauling out on ice floes may have avoided icebreaking activities within 10—15 km (6.2—9.3 mi) (Brueggeman
et al.,
1990).

Ringed and bearded seals on pack ice approached by an icebreaker typically dove into the water within 0.93 km (0.58 mi) of the vessel but tended to be less responsive when the same ship was underway in open water (Brueggeman
et al.,
1992). In another study, ringed and harp seals remained on the ice when an icebreaker was 1-2 km (0.62—1.2 mi) away, but seals often dove into the water when closer to the icebreaker (Kanik
et al.,
1980 in Richardson
et al.,
1995a). Ringed seals have also been seen feeding among overturned ice floes in the wake of icebreakers (Brewer
et al.,
1993).

Seals swimming are likely to avoid approaching vessels by a few meters to a few tens of meters, while some “curious” seals are likely to swim toward vessels. Seals hauled out on ice also show mixed reaction to approaching vessels/icebreakers. Seals are likely to dive into the water if the icebreaker comes within 1 km (0.62 mi). The impact of vessel traffic on seals is expected to be negligible.

One potential impact from icebreaking activities is ice entrapment of pinnipeds that are following the vessels. However, NMFS does not consider this likely because ice formation at the time of the proposed survey consists mostly of loose annual ice floes that will not freeze into extensive pack ice. In addition, the time chosen for the icebreaking seismic survey would occur before ringed seals start constructing lairs in ice around early March.

Finally, the breaking of heavy pack ice or thick landfast ice could also indirectly increase the level of ambient noise due to broken ice floes cracking against each other, and effectively change the area's soundscape.

Vessel Sounds

In addition to the noise generated from seismic airguns and active sonar systems, various types of vessels will be used in the operations, including source vessels and support vessels. Sounds from boats and vessels have been reported extensively (Greene and Moore, 1995; Blackwell and Greene, 2002; 2005; 2006). Numerous measurements of underwater vessel sound have been performed in support of recent industry activity in the Chukchi and Beaufort Seas. Results of these measurements have been reported in various 90-day and comprehensive reports since 2007 (
e.g.,
Aerts
et al.,
2008; Hauser
et al.,
2008; Brueggeman, 2009; Ireland
et al.,
2009). For example, Garner and Hannay (2009) estimated sound pressure levels of 100 dB at distances ranging from approximately 2.4 to 3.7 km (1.5 to 2.3 mi) from various types of barges. MacDonald
et al.
(2008) estimated higher underwater SPLs from the seismic vessel
Gilavar
of 120 dB at approximately 21 km (13 mi) from the source, although the sound level was only 150 dB at 26 m (85 ft) from the vessel. Compared to airgun pulses, underwater sound from vessels is generally at relatively low levels.

The primary sources of sounds from all vessel classes are propeller cavitation, propeller singing, and propulsion or other machinery. Propeller cavitation is usually the dominant noise source for vessels (Ross, 1976). Propeller cavitation and singing are produced outside the hull, whereas propulsion or other machinery noise originates inside the hull. There are additional sounds produced by vessel activity, such as pumps, generators, flow noise from water passing over the

hull, and bubbles breaking in the wake. Icebreakers contribute greater sound levels during ice-breaking activities than ships of similar size during normal operation in open water (Richardson
et al.,
1995). This higher sound production results from the greater amount of power and propeller cavitation required when operating in thick ice. Source levels from various vessels would be empirically measured before the start of marine surveys.

For this project, the majority of any vessel noise would occur concurrently with sounds generated by seismic airguns or icebreaking and any potential impacts would be expected to be subsumed by the impacts of those louder sources.

Anticipated Effects on Habitat

The primary potential impacts to marine mammals and other marine species are associated with elevated sound levels produced by airguns and other active acoustic sources, noise generated from icebreaking, and breaking of ice during the seismic survey. However, other potential impacts to the surrounding habitat from physical disturbance are also possible.

Potential Impacts on Prey Species

With regard to fish as a prey source for cetaceans and pinnipeds, fish are known to hear and react to sounds and to use sound to communicate (Tavolga
et al.,
1981) and possibly avoid predators (Wilson and Dill, 2002). Experiments have shown that fish can sense both the strength and direction of sound (Hawkins, 1981). Primary factors determining whether a fish can sense a sound signal, and potentially react to it, are the frequency of the signal and the strength of the signal in relation to the natural background noise level.

The level of sound at which a fish will react or alter its behavior is usually well above the detection level. Fish have been found to react to sounds when the sound level increased to about 20 dB above the detection level of 120 dB (Ona, 1988); however, the response threshold can depend on the time of year and the fish's physiological condition (Engas
et al.,
1993). In general, fish react more strongly to pulses of sound rather than a continuous signal (such as noise from a vessel or icebreaking) (Blaxter
et al.,
1981), and a quicker alarm response is elicited when the sound signal intensity rises rapidly compared to sound rising more slowly to the same level.

Investigations of fish behavior in relation to vessel noise (Olsen
et al.,
1983; Ona, 1988; Ona and Godo, 1990) have shown that fish react when the sound from the engines and propeller exceeds a certain level. Avoidance reactions have been observed in fish, such as cod and herring, when vessels approached close enough that received sound levels are 110 dB to 130 dB (Nakken, 1992; Olsen, 1979; Ona and Godo, 1990; Ona and Toresen, 1988). However, other researchers have found that fish such as polar cod, herring, and capeline are often attracted to vessels (apparently by the noise) and swim toward the vessel (Rostad
et al.,
2006). Typical sound source levels of vessel noise in the audible range for fish are 150 dB to 170 dB (Richardson
et al.,
1995).

Further, during the proposed in-ice seismic survey, only a small fraction of the available habitat would be ensonified at any given time. Disturbance to fish species would be short-term, and fish would return to their pre-disturbance behavior once the seismic activity ceases (McCauley
et al.,
2000a, 2000b; Santulli
et al.,
1999; Pearson
et al.,
1992). Thus, the proposed survey would have little, if any, impact on the abilities of marine mammals to feed in the area where seismic work is planned.

Some mysticetes, including bowhead whales, feed on concentrations of zooplankton. Some feeding bowhead whales may occur in the Alaskan Beaufort Sea in July and August, and others feed intermittently during their westward migration in September and October (Richardson and Thomson [eds.] 2002; Lowry
et al.,
2004). However, by the time most bowhead whales reach the Chukchi Sea (October), they will likely no longer be feeding, or if feeding occurs it will be very limited. A reaction by zooplankton to a seismic impulse would only be relevant to whales if it caused concentrations of zooplankton to scatter. Pressure changes of sufficient magnitude to cause that type of reaction would probably occur only very close to the source. Impacts on zooplankton behavior are predicted to be inconsequential, and that would translate into negligible impacts on feeding mysticetes. Because ION will not start operations until early October, a substantial portion of the bowhead population that feeds in the Beaufort Sea during the fall westward migration will have already completed feeding and migrated out of the area before the proposed survey begins. Thus, the proposed activity is not expected to have any habitat-related effects on prey species or feeding marine mammals that could cause significant or long-term consequences for individual marine mammals or their populations.

Potential Impacts on Physical Environment

The proposed airgun operations will not result in any permanent impact on habitats used by marine mammals or to their food sources. The main impact issue associated with the proposed activities would be temporarily elevated noise levels and their associated direct effects on marine mammals, as discussed above, as well as the potential effects of icebreaking. The potential effects of icebreaking include locally altered ice conditions and the potential for the destruction of ringed seal lairs. However, ringed seals are not expected to enter these structures until later in the season, after the completion of ION's activities. Ice conditions at this time of year are typically quite variable with new leads opening and pressure ridges forming as wind and waves move the newly forming ice. This dynamic environment may be responsible for the mean date of permanent den entry on sea ice in the Beaufort Sea being later than on land (Amstrup and Gardner, 1994). The icebreaker and seismic vessel transit is not expected to significantly alter the formation of sea ice during this period.

Icebreaking would open leads in the sea ice along the vessel tracklines and could potentially destroy ringed seal lairs. However, ringed seals will not need lairs for pupping until the late winter or spring (after ION completes operations), so the impacts are not expected to impact pup survival. Ringed seals excavate lairs in snow that accumulates on sea ice near their breathing holes, and an individual seal maintains several breathing holes (Smith and Stirling, 1975). Ringed seal lairs are found in snow depths of 20-150 cm (8-59 in) (Smith and Stirling, 1975), and seals are not expected to enter lairs before the proposed seismic survey takes place. Damage to lairs caused by survey activities is not expected to exceed that which occurs naturally, and lair destruction in the early winter would likely not impact ringed seal survival. Lanugal pups born in the spring can become hypothermic if wetted, but by early winter they are robust to submersion having spent the entire summer at sea (Smith
et al.,
1991). The highest density of ringed seals reported from aerial surveys conducted during spring when seals were emerging from lairs was in areas with water depth ranging from 5-35 m (16.4-115 ft) (Frost
et al.,
2004). A relatively small proportion (5%; 364 km [226 mi]) of the proposed survey trackline is planned in that area.

During the seismic survey only a small fraction of the available habitat would be ensonified at any given time. Disturbance to fish species would be short-term, and fish are expected to return to their pre-disturbance behavior once the seismic activity ceases (McCauley
et al.,
2000a, b; Santulli
et al.,
1999; Pearson
et al.,
1992). Thus, the proposed survey would have little, if any, impact on the abilities of marine mammals to feed in the area where seismic work is planned.

Refueling at sea has the potential to impact the marine environment if a spill were to occur. However, there are multiple procedures and safeguards in place to avoid such an accident. Prior to conducting a fuel transfer, the area around the vessels would be checked for the presence of marine mammals and operations delayed until the area is clear. A leak during refueling would be detected and the system shut down within a maximum of 30 seconds. The diesel oil transfer pump is rated at 50 IGPM @ 60 ft pressure head. Therefore, the maximum amount of oil that could be spilled during a transfer is 25 imperial gallons. This risk is reduced further with the standard use of `dry-break' fittings for fuel transfers.

Based on the information provided in this section, the proposed activity is not expected to have any habitat-related effects that could cause significant or long-term consequences for individual marine mammals or their populations.

Potential Impacts on Availability of Affected Species or Stock for Taking for Subsistence Uses

Relevant Subsistence Uses

Subsistence hunting and fishing continue to be prominent in the household economies and social welfare of some Alaskan residents, particularly among those living in small, rural villages (Wolfe and Walker, 1987). The disturbance and potential displacement of marine mammals by sounds from the proposed marine surveys are the principal concerns related to subsistence use of the area. 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. (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.

(1) Bowhead Whales

Bowhead whale hunting is a key activity in the subsistence economies of Barrow and other Native communities along the Beaufort Sea and Chukchi Sea coast. The whale harvests have a great influence on social relations by strengthening the sense of Inupiat culture and heritage in addition to reinforcing family and community ties.

An overall quota system for the hunting of bowhead whales was established by the International Whaling Commission in 1977. The quota is now regulated through an agreement between NMFS and the Alaska Eskimo Whaling Commission (AEWC). The AEWC allots the number of bowhead whales that each whaling community may harvest annually during five-year periods (USDI/BLM, 2005). NMFS proposed continuation of the bowhead hunt for the five-year period 2008-2012 (NMFS, 2008b), and in June 2012, NMFS released a Draft Environmental Impact Statement proposing to continue the bowhead hunt for the period 2013-2017/2018 (NMFS, 2012).

The community of Barrow hunts bowhead whales in both the spring and fall during the whales' seasonal migrations along the coast. Often the bulk of the Barrow bowhead harvest is taken during the spring hunt. However, with larger quotas in recent years, it is common for a substantial fraction of the annual Barrow quota to remain available for the fall hunt. The communities of Nuiqsut and Kaktovik participate only in the fall bowhead harvest. The fall migration of bowhead whales that summer in the eastern Beaufort Sea typically begins in late August or September. Fall migration into Alaskan waters is primarily during September and October. However, in recent years a small number of bowheads have been seen or heard offshore from the Prudhoe Bay region during the last week of August (Treacy, 1993; LGL and Greeneridge, 1996; Greene, 1997; Greene
et al.,
1999; Blackwell
et al.,
2004).

In autumn, westward-migrating bowhead whales typically reach the Kaktovik and Cross Island (Nuiqsut hunters) areas by early September, at which points the hunts begin (Kaleak, 1996; Long, 1996; Galginaitis and Koski, 2002; Galginaitis and Funk, 2004, 2005; Koski
et al.,
2005). Around late August, the hunters from Nuiqsut establish camps on Cross Island from where they undertake the fall bowhead whale hunt. The hunting period starts normally in early September and may last as late as mid-October, depending mainly on ice and weather conditions and the success of the hunt. Most of the hunt occurs offshore in waters east, north, and northwest of Cross Island where bowheads migrate and not inside the barrier islands (Galginaitis, 2007). Hunters prefer to take bowheads close to shore to avoid a long tow during which the meat can spoil, but Braund and Moorehead (1995) report that crews may (rarely) pursue whales as far as 80 km (50 mi) offshore. Whaling crews use Kaktovik as their home base, leaving the village and returning on a daily basis. The core whaling area is within 19.3 km (12 mi) of the village with a periphery ranging about 13 km (8 mi) farther, if necessary. The extreme limits of the Kaktovik whaling limit would be the middle of Camden Bay to the west. The timing of the Kaktovik bowhead whale hunt roughly parallels the Cross Island whale hunt (Impact Assessment Inc, 1990b; SRB&A, 2009:Map 64). In recent years, the hunts at Kaktovik and Cross Island have usually ended by mid- to late September (prior to the proposed start date for ION's seismic survey).

The spring hunts at Wainwright and Barrow occur after leads open due to the deterioration of pack ice; the spring hunt typically occurs from early April until the first week of June. The location of the fall subsistence hunt depends on ice conditions and (in some years) industrial activities that influence the bowheads as they move west (Brower, 1996). In the fall, subsistence hunters use aluminum or fiberglass boats with outboards. At Barrow the fall hunt usually begins in mid-September, and mainly occurs in the waters east and northeast of Point Barrow. In 2007 however, all bowheads taken in fall at Barrow were harvested west of Pt. Barrow in the Chukchi Sea (Suydam
et al.,
2008). The whales have usually left the Beaufort Sea by late October (Treacy, 2002a; 2002b).

The scheduling of this seismic survey was introduced to representatives of those concerned with the subsistence bowhead hunt including the AEWC and the North Slope Borough (NSB) Department of Wildlife Management during a meeting in Barrow on December 15, 2009. Additional meetings occurred in 2010, 2011, and 2012 with more planned later in 2012 to share information regarding the survey with other members of the subsistence hunting community. The timing of the proposed geophysical survey in October-December will not affect the

spring bowhead hunt. The fall bowhead hunt may be occurring near Barrow during October, and operations will be coordinated with the AEWC. ION will operate at the eastern end of the survey area until fall whaling in the Beaufort Sea near Barrow is finished. Fall bowhead whale hunts by members of the communities of Kaktovik and Nuiqsut will likely be completed prior to October.

Whaling communities of the Bering Strait area, such as Gambell and Savoonga on St. Lawrence Island, hunt bowheads in the late fall (typically around Thanksgiving). Because ION intends to conduct operations in the Beaufort and Chukchi Seas until early to mid-December, ION's vessel transits through the Bering Strait should not interfere with these late fall hunts.

(2) Beluga Whales

Beluga whales are available to subsistence hunters at Barrow in the spring when pack-ice conditions deteriorate and leads open up. Belugas may remain in the area through June and some-times into July and August in ice-free waters. Hunters usually wait until after the spring bowhead whale hunt is finished before turning their attention to hunting belugas. The average annual harvest of beluga whales taken by Barrow for 1962-1982 was five (MMS, 1996). The Alaska Beluga Whale Committee recorded that 23 beluga whales had been harvested by Barrow hunters from 1987 to 2002, ranging from 0 in 1987, 1988 and 1995 to the high of 8 in 1997 (Fuller and George, 1999; Alaska Beluga Whale Committee, 2002 in USDI/BLM, 2005). The timing of the proposed survey will not overlap with the beluga harvest.

(3) Ice Seals

Ringed seals are hunted mainly from October through June. Hunting for these smaller mammals is concentrated during winter because bowhead whales, bearded seals and caribou are available through other seasons. In winter, leads and cracks in the ice off points of land and along the barrier islands are used for hunting ringed seals. The seismic survey would be largely in offshore waters where the activities would not influence ringed seals in the nearshore areas where they are hunted.

The spotted seal subsistence hunt peaks in July and August, at least in 1987 to 1990, but involves few animals. Spotted seals typically migrate south by October to overwinter in the Bering Sea, and therefore the proposed October-December survey will not affect hunting of this species. Admiralty Bay, less than 60 km (37 mi) to the east of Barrow, is a location where spotted seals are harvested. Spotted seals are also occasionally hunted in the area off Point Barrow and along the barrier islands of Elson Lagoon to the east (USDI/BLM, 2005). The average annual spotted seal harvest by the community of Barrow from 1987-1990 was one (Braund
et al.,
1993)

Bearded seals, although not favored for their meat, are important to subsistence activities in Barrow because of their skins. Six to nine bearded seal hides are used by whalers to cover each of the skin-covered boats traditionally used for spring whaling. Because of their valuable hides and large size, bearded seals are specifically sought. Bearded seals are harvested during the summer months in the Beaufort Sea (USDI/BLM, 2005). The animals inhabit the environment around the ice floes in the drifting ice pack, so hunting usually occurs from boats in the drift ice. Braund
et al.
(1993) mapped the majority of bearded seal harvest sites from 1987 to 1990 as being within ~24 km (~15 mi) of Point Barrow. The average annual take of bearded seals by the Barrow community from 1987 to 1990 was 174. Because bearded seal hunting typically occurs during the summer months, the proposed October-December survey is not expected to affect bearded seal harvests.

Potential Impacts to Subsistence Uses

NMFS has defined “unmitigable adverse impact” in 50 CFR 216.103 as: “* * * an impact resulting from the specified activity: (1) That is likely to reduce the availability of the species to a level insufficient for a harvest to meet subsistence needs by: (i) Causing the marine mammals to abandon or avoid hunting areas; (ii) Directly displacing subsistence users; or (iii) Placing physical barriers between the marine mammals and the subsistence hunters; and (2) That cannot be sufficiently mitigated by other measures to increase the availability of marine mammals to allow subsistence needs to be met.”

Seismic surveys and associated icebreaking operations have the potential to impact marine mammals hunted by Native Alaskans. In the case of cetaceans, the most common reaction to anthropogenic sounds (as noted previously in this document) is avoidance of the ensonified area. In the case of bowhead whales, this often means that the animals could divert from their normal migratory path by up to several kilometers. Additionally, general vessel presence in the vicinity of traditional hunting areas could negatively impact a hunt.

In the case of subsistence hunts for bowhead whales in the Beaufort and Chukchi Seas, 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. Native knowledge indicates that bowhead whales become increasingly “skittish” in the presence of seismic noise. Whales are more wary around the hunters and tend to expose a much smaller portion of their back when surfacing (which makes harvesting more difficult). Additionally, natives report that bowheads exhibit angry behaviors in the presence of seismic, such as tail-slapping, which translate to danger for nearby subsistence harvesters.

However, due to its proposed time and location, ION's proposed in-ice seismic survey in the Beaufort and Chukchi Seas would be unlikely to result in the aforementioned impacts. As discussed earlier in detail, the only potential impacts on subsistence use of marine mammals from ION's proposed icebreaking seismic survey during October-December period are the fall bowhead hunt and ringed seal harvest. Nevertheless, the proposed seismic survey is expected to occur in waters far offshore from the regular seal hunting areas, and ION indicates it would elect to operate at the eastern end of the survey area until fall whaling in the Beaufort Sea near Barrow is finished, thus reducing the likelihood of interfering with subsistence use of marine mammals in the vicinity of the project area.

Proposed Mitigation

In order to issue an incidental take authorization (ITA) under Section 101(a)(5)(D) of the MMPA, NMFS must set forth the permissible methods of taking pursuant to such activity, and other means of effecting the least practicable impact on such species or stock and its habitat, paying particular attention to rookeries, mating grounds, and areas of similar significance, and on the availability of such species or stock for taking for certain subsistence uses.

For the proposed ION in-ice seismic survey in the Beaufort and Chukchi Seas, ION worked with NMFS and proposed the following mitigation measures to minimize the potential impacts to marine mammals in the project vicinity as a result of the marine seismic survey activities.

As part of the application, ION submitted to NMFS a Marine Mammal Monitoring and Mitigation Program (4MP) for its in-ice seismic survey in the Beaufort and Chukchi Seas during the 2012 fall season. The objectives of the 4MP are:

• To ensure that disturbance to marine mammals and subsistence hunts is minimized and all permit stipulations are followed,

• To document the effects of the proposed survey activities on marine mammals, and

• To collect baseline data on the occurrence and distribution of marine mammals in the study area.

The 4MP 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).

Mitigation Measures Proposed in ION's IHA Application

ION listed the following protocols to be implemented during its marine seismic survey in the Beaufort and Chukchi Seas.

(1) Exclusion Zones

Under current NMFS guidelines, “exclusion zones” for marine mammals around industrial sound sources are customarily defined as the distances within which received sound levels are ≥180 dB re 1 μPa (rms) for cetaceans and ≥190 dB re 1 μPa (rms) for pinnipeds. These criteria are based on an assumption that sound energy at lower received levels will not injure these animals or impair their hearing abilities but that higher received levels might have some such effects. Disturbance or behavioral effects to marine mammals from underwater sound may occur after exposure to sound at distances greater than the exclusion zone (Richardson
et al.,
1995; see above).

Received sound levels were modeled for the full 26 airgun, 4,450 in
3
array in relation to distance and direction from the source (Zykov
et al.,
2010). Based on the model results, Table 1 in this document shows the distances from the airguns where ION predicts that received sound levels will drop below 190, 180, and 160 dB re 1 μPa (rms). A single 70-in
3
airgun would be used during turns or if a power down of the full array (see below) is necessary due to the presence of a marine mammal within or about to enter the applicable exclusion zone of the full airgun array. To model the source level of the 70-in
3
airgun, ION used the measurements of a 30-in
3
airgun. Underwater sound propagation of a 30-in
3
airgun was measured in <100 m (328 ft) of water near Harrison Bay in 2007, and results were reported in Funk
et al.
(2008). The constant term of the resulting equation was increased by 2.45 dB based on the difference between the volume of the two airguns [2.45 = 20Log(70/30)‸(
1/3
)]. The 190 and 180 dB (rms) distances for the 70-in
3
airgun from the adjusted equation, 19 m (62 ft) and 86 m (282 ft) respectively, would be used as the exclusion zones around the single 70 in
3
airgun in all water depths until results from field measurements are available.

An acoustics contractor would perform the direct measurements of the received levels of underwater sound versus distance and direction from the energy source arrays using calibrated hydrophones (see below “Sound Source Verification” in the “Proposed Monitoring” section). The acoustic data would be analyzed as quickly as reasonably practicable in the field and used to verify (and if necessary adjust) the size of the exclusion zones. The field report will be made available to NMFS and the Protected Species Observers (PSOs) within 120 hrs of completing the measurements. The mitigation measures to be implemented at the 190 and 180 dB (rms) sound levels would include power downs and shut downs as described below.

Table 1—Marine Mammal Exclusion Zones From the 26 Airgun, 4,450-in
3
Array, for Specific Categories Based on the Water Depth

rms (dB re. 1 μPa)
Exclusion and disturbance zones (meters)

less than
100 m

100 m-
1,000 m

more than 1,000 m

190
600
180
180

180
2,850
660
580

160
27,800
42,200
31,600

(2) Speed or Course Alteration

If a marine mammal (in water) is detected outside the exclusion zone and, based on its position and the relative motion, is likely to enter the exclusion zone, the vessel's speed and/or direct course shall be changed in a manner that also minimizes the effect on the planned objectives when such a maneuver is safe.

Another measure proposes to avoid concentrations or groups of whales by all vessels in transit under the direction of ION. Operators of vessels should, at all times, conduct their activities at the maximum distance possible from such concentrations of whales.

All vessels during transit shall be operated at speeds necessary to ensure no physical contact with whales occurs. If any barge or transit vessel approaches within 1.6 km (1 mi) of observed bowhead whales, the vessel operator shall take reasonable precautions to avoid potential interaction with the bowhead whales by taking one or more of the following actions, as appropriate:

(A) Reducing vessel speed to less than 5 knots within 300 yards (900 feet or 274 m) of the whale(s);

(B) Steering around the whale(s) if possible;

(C) Operating the vessel(s) in such a way as to avoid separating members of a group of whales from other members of the group;

(D) Operating the vessel(s) to avoid causing a whale to make multiple changes in direction; and

(E) Checking the waters immediately adjacent to the vessel(s) to ensure that no whales will be injured when the propellers are engaged.

When weather conditions require, such as when visibility drops, adjust vessel speed accordingly to avoid the likelihood of injury to whales.

In the event that any aircraft (such as helicopters) are used to support the planned survey, the proposed mitigation measures below would apply:

(A) Under no circumstances, other than an emergency, shall aircraft be operated at an altitude lower than 1,000 feet above sea level (ASL) when within 0.3 mile (0.5 km) of groups of whales.

(B) Helicopters shall not hover or circle above or within 0.3 mile (0.5 km) of groups of whales.

(3) Ramp Ups

A ramp up of an airgun array provides a gradual increase in sound levels and involves a step-wise increase in the number and total volume of airguns firing until the full volume is achieved. The purpose of a ramp up is to “warn” marine mammals in the vicinity of the airguns and to provide the time for them to leave the area and thus avoid any potential injury or impairment of their hearing abilities.

During the proposed seismic survey program, the seismic operator will ramp up the airgun arrays slowly. Full ramp ups (
i.e.,
from a cold start after a shut down or when no airguns have been firing) will begin by firing a single airgun in the array. A full ramp up, following a cold start, can be applied if the exclusion zone has been free of marine mammals for a consecutive 30-minute period. The entire exclusion zone must have been visible during these 30 minutes. If the entire exclusion zone is not visible, then ramp up from a cold start cannot begin.

Ramp up procedures from a cold start shall be delayed if a marine mammal is sighted within the exclusion zone during the 30-minute period prior to the ramp up. The delay shall last until the marine mammal(s) has been observed to leave the exclusion zone or until the animal(s) is not sighted for at least 15 or 30 minutes. The 15 minutes applies to small odontocetes and pinnipeds, while a 30 minute observation period applies to baleen whales and large toothed whales.

A ramp up, following a shutdown, can be applied if the marine mammal(s) for which the shutdown occurred has been observed to leave the exclusion zone or until the animal(s) is not sighted for at least 15 minutes (small odontocetes and pinnipeds) or 30 minutes (baleen whales and large toothed whales).

If, for any reason, electrical power to the airgun array has been discontinued for a period of 10 minutes or more, ramp-up procedures shall be implemented. Only if the PSO watch has been suspended, a 30-minute clearance of the exclusion zone is required prior to commencing ramp-up. Discontinuation of airgun activity for less than 10 minutes does not require a ramp-up.

The seismic operator and PSOs shall maintain records of the times when ramp-ups start and when the airgun arrays reach full power.

During turns and transit between seismic transects, the 70 in
3
mitigation gun will remain operational. The ramp up procedure will still be followed when increasing the source levels from one airgun to the full array. PSOs will be on duty whenever the airguns are firing during daylight and during the 30 minute periods prior to full ramp ups. Daylight will occur for ~11 hours/day at the start of the survey in early October diminishing to ~3 hours/day in mid-November.

(4) Power Down Procedures

A power down involves decreasing the number of airguns in use such that the radii of the 190 and 180 dB re 1 μPa (rms) zones are decreased to the extent that observed marine mammals are not in the applicable exclusion zone. A power down may also occur when the vessel is moving from one seismic line to another. During a power down, only one airgun is operated. The continued operation of one airgun is intended to (a) alert marine mammals to the presence of the seismic vessel in the area, and (b) retain the option of initiating a ramp up to full array under poor visibility conditions. In contrast, a shutdown is when all airgun activity is suspended (see next section).

If a marine mammal is detected outside the exclusion zone but is likely to enter the exclusion zone, and if the vessel's speed and/or course cannot be changed to avoid having the mammal enter the exclusion zone, the airguns may (as an alternative to a complete shutdown) be powered down before the mammal is within the exclusion zone. Likewise, if a mammal is already within the exclusion zone when first detected, the airguns will be powered down immediately if this is a reasonable alternative to a complete shutdown. During a power down of the array, the number of guns operating will be reduced to a single 70 in
3
airgun. The pre-season estimates of the 190 dB re 1 μPa (rms) and 180 dB re 1 μPa (rms) exclusion zones around the power down source are 19 m (62 ft) and 86 m (282 ft), respectively. The 70 in
3
airgun power down source will be measured during acoustic sound source measurements conducted at the start of seismic operations. If a marine mammal is detected within or near the applicable exclusion zone around the single 70 in
3
airgun, it too will be deactivated, resulting in a complete shutdown (see next subsection).

Marine mammals hauled out on ice may enter the water when approached closely by a vessel. If a marine mammal on ice is detected by PSOs within the exclusion zones, it will be watched carefully in case it enters the water. In the event the animal does enter the water and is within an applicable exclusion zone of the airguns during seismic operations, a power down or other necessary mitigation measures will immediately be implemented. If the animal does not enter the water, it will not be exposed to sounds at received levels for which mitigation is required; therefore, no mitigation measures will be taken.

Following a power down, operation of the full airgun array will not resume until the marine mammal has cleared the exclusion zone. The animal will be considered to have cleared the exclusion zone if it:

• Is visually observed to have left the exclusion zone, or

• Has not been seen within the zone for 15 min in the case of pinnipeds (excluding walruses) or small odontocetes, or

• Has not been seen within the zone for 30 min in the case of mysticetes or large odontocetes.

(5) Shutdown Procedures

The operating airgun(s) will be shut down completely if a marine mammal approaches or enters the then-applicable exclusion zone and a power down is not practical or adequate to reduce exposure to less than 190 or 180 dB re 1 μPa (rms). The operating airgun(s) will also be shut down completely if a marine mammal approaches or enters the estimated exclusion zone around the reduced source (one 70 in
3
airgun) that will be used during a power down.

Airgun activity will not resume until the marine mammal has cleared the exclusion zone. The animal will be considered to have cleared the exclusion zone if it is visually observed to have left the exclusion zone, or if it has not been seen within the zone for 15 min (pinnipeds and small odontocetes) or 30 min (mysticetes and large odontocetes). Ramp up procedures will be followed during resumption of full seismic operations after a shutdown of the airgun array.

Additional Mitigation Measures Proposed by NMFS

In addition to ION's proposed mitigation measures discussed above, NMFS proposes the following additional measures during the long periods of darkness when the seismic survey is proposed. Specifically in this case, With the exception of turns when starting a new trackline, or short transits or maintenance with a duration of less than one hour, NMFS does not recommend keeping one airgun (also referred to as the “mitigation gun” in past IHAs) firing for long periods of time during darkness or other periods of poor visibility, as it would only introduce more noise into the water with no

potential near-term avoidance benefits for marine mammals.

Furthermore, NMFS proposes that the airgun array be shut down if a pinniped is sighted hauled out on ice within the underwater exclusion zone (received level 190 dB re 1 μPa (rms)). Even though the pinniped may not be exposed to in-air noise levels that could be considered a take, the presence of the seismic vessel could prompt the animal to slip into the water, and thus be exposed to a high intensity sound field as a result.

Mitigation Measures for Subsistence Activities

(1) Subsistence Mitigation Measures

Since ION's proposed October-December in-ice seismic survey in the Beaufort and Chukchi Seas is not expected to affect subsistence use of marine mammals by Alaskan Natives due to its proposed time and location, no specific mitigation measures are proposed other than those general mitigation measures discussed above.

(2) Plan of Cooperation (POC)

Regulations at 50 CFR 216.104(a)(12) require IHA applicants for activities that take place in Arctic waters to provide a POC or information that identifies what measures have been taken and/or will be taken to minimize adverse effects on the availability of marine mammals for subsistence purposes.

ION has developed a “Plan of Cooperation” (POC) for the proposed 2012 seismic survey in the Beaufort and Chukchi Seas in consultation with representatives of Barrow, Nuiqsut, Kaktovik, and Wainwright and subsistence users within these communities. NMFS received a final draft of the POC on May 22, 2012. The final draft POC is posted on NMFS Web site at
http://www.nmfs.noaa.gov/pr/permits/incidental.htm#applications.

ION will continue to engage with the communities of Barrow, Nuiqsut, Kaktovik, and Wainwright to identify and avoid areas of potential conflict. The meetings with stakeholders that took place in 2010 and 2011 are listed in Table 16 and Table 17, respectively, of ION's IHA application. The meetings that have taken place in 2012, as well as additional proposed meetings, are listed in Table 18 of ION's IHA application. Members of marine mammal co-management groups and groups that address subsistence activities were specifically notified of the public meetings so that they could provide input. A record of all consultation with subsistence users will be included in the 2012 Final POC document.

Mitigation Conclusions

NMFS has carefully evaluated the applicant's proposed mitigation measures and considered a range of other measures in the context of ensuring that NMFS prescribes the means of effecting the least practicable impact on the affected marine mammal species and stocks and their habitat. Our evaluation of potential measures included consideration of the following factors in relation to one another:

• The manner in which, and the degree to which, the successful implementation of the measure is expected to minimize adverse impacts to marine mammals;

• 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, as well as other measures considered by NMFS, NMFS has preliminarily determined that the proposed mitigation measures provide the means of effecting the least prac

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Source: Frix Law Library, https://www.frixlaw.com/law-library/documents/fr%3A2012-20173. Public record. Not legal advice.