Small Takes of Marine Mammals Incidental to Specified Activities; Open-water Marine Survey Program in the Chukchi Sea, Alaska, During 2009-2010

DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

RIN 0648-XP00

Small Takes of Marine Mammals Incidental to Specified Activities; Open-water Marine Survey Program in the Chukchi Sea, Alaska, During 2009-2010

AGENCY:

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

ACTION:

Notice; issuance of an incidental take authorization.

SUMMARY:

In accordance with the Marine Mammal Protection Act (MMPA) regulations, notification is hereby given that NMFS has issued an Incidental Harassment Authorization (IHA) to Shell Offshore Inc. and Shell Gulf of Mexico Inc., collectively known as Shell, to take, by harassment, small numbers of 12 species of marine mammals incidental to an open-water marine survey program, which includes shallow hazards and site clearance work and strudel scour surveys, in the Chukchi Sea, Alaska, during the 2009/2010 Arctic open-water season.

DATES:

Effective August 19, 2009, through August 18, 2010.

ADDRESSES:

A copy of the application containing a list of the references used in this document, two addenda to the application, NMFS' Environmental Assessment (EA) and Finding of No Significant Impact (FONSI), and the IHA may be obtained by writing to the address specified above, telephoning the contact listed below (see

FOR FURTHER INFORMATION CONTACT

), or visiting the Internet at:

http://www.nmfs.noaa.gov/pr/permits/incidental.htm#applications

.

Documents cited in this notice may be viewed, by appointment, during regular business hours, at the aforementioned address.

FOR FURTHER INFORMATION CONTACT:

Candace Nachman, Office of Protected Resources, NMFS, (301) 713-2289 or Brad Smith, NMFS, Alaska Region, (907) 271-3023.

SUPPLEMENTARY INFORMATION:

Background

Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361

et seq.

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

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

Section 101(a)(5)(D) of the MMPA established an expedited process by which citizens of the U.S. can apply for an authorization to incidentally take small numbers of marine mammals by harassment. Except with respect to certain activities not pertinent here, the MMPA defines “harassment” as:

any act of pursuit, torment, or annoyance which (i) has the potential to injure a marine mammal or marine mammal stock in the wild [Level A harassment]; or (ii) has the potential to disturb a marine mammal or marine mammal stock in the wild by causing disruption of behavioral patterns, including, but not limited to, migration, breathing, nursing, breeding, feeding, or sheltering [Level B harassment].

Section 101(a)(5)(D) establishes a 45-day time limit for NMFS review of an application followed by a 30-day public notice and comment period on any proposed authorization 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.

Summary of Request

On December 15, 2008, NMFS received an application from Shell for the taking, by Level B harassment only, of small numbers of several species of marine mammals incidental to conducting an open-water marine survey program during the 2009/2010 Arctic open-water season in the Chukchi Sea. Shell plans to conduct site clearance and shallow hazards surveys and a strudel scour survey in the Chukchi Sea. These surveys are a continuation of those conducted by Shell in the Chukchi Sea in 2008. Shell's December 2008, application also requested MMPA coverage for site clearance and shallow hazards surveys, an ice gouge survey, and a strudel scour survey in the Beaufort Sea and an ice gouge survey in the Chukchi Sea for the 2009/2010 season. However, in an addendum to the IHA application submitted to NMFS on March 10, 2009, Shell indicated that it cancelled all survey programs for the Beaufort Sea and the ice gouge survey for the Chukchi Sea in 2009. Shell submitted a second application addendum on May 19, 2009, indicating that Shell will utilize an array of 4 x 10 in

3

guns (40 in

3

total discharge volume) instead of the 2 x 10 in

3

array (20 in

3

total discharge volume).

Site clearance and shallow hazards surveys will evaluate the seafloor and shallow sub-seafloor at prospective exploration drilling locations, focusing on the depth to seafloor, topography, the potential for shallow faults or gas zones, and the presence of archaeological features. The types of equipment used to conduct these surveys use low level energy sources focused on limited areas in order to characterize the footprint of the seafloor and shallow sub-seafloor at prospective drilling locations.

Description of the Specified Activity

Chukchi Site Clearance and Shallow Hazards Surveys

Site clearance and shallow hazards surveys of potential proposed locations for exploration drilling will be executed as required by the Minerals Management Service's (MMS) regulations. These surveys gather data on: (1) bathymetry; (2) seabed topography and other seabed characteristics (e.g., boulder patches); (3) potential geohazards (e.g., shallow faults and shallow gas zones); and (4) the presence of any archeological features (e.g., shipwrecks). Site clearance and shallow hazards surveys can be accomplished by one vessel with acoustic sources. A detailed overview of the activities of this survey was provided in the Notice of Proposed IHA (74 FR 26217, June 1, 2009). Since publication of that notice, Shell updated two pieces of information. First, the

R/V Mt. Mitchell

will be utilized as the source vessel for the site clearance and shallow hazards surveys. The

R/V Mt. Mitchell

is a diesel powered vessel, 70 m (231 ft) long, 12.7 m (42 ft) wide, with a 4.5 m (15 ft) draft. Second, the specific prospects within Outer Continental Shelf (OCS) Lease Sale (LS) 193 have been identified. Shell will conduct the surveys at the Burger and Crackerjack prospects and, if time and weather conditions permit, at SW Shoebill. Additional information is also

contained in Shell's application and application addenda, which are available for review (see

ADDRESSES

).

Chukchi Strudel Scour Survey

During the early melt, the rivers begin to flow and discharge water over the coastal sea ice near the river deltas. That water rushes down holes in the ice (“strudels”) and scours the seafloor. These erosional areas are called “strudel scours”. Information on these features is required for prospective pipeline planning. Two proposed activities are required to gather this information: aerial survey via helicopter overflights during the melt to locate the strudels and strudel scour marine surveys to gather bathymetric data. Additional information was provided in the Notice of Proposed IHA (74 FR 26217, June 1, 2009) and Shell's application (see

ADDRESSES

).

Comments and Responses

A notice of receipt of Shell's MMPA application and NMFS' proposal to issue an IHA to Shell published in the

Federal Register

on June 1, 2009 (74 FR 26217). That notice described, in detail, Shell's proposed activity, the marine mammal species that may be affected by the activity, and the anticipated effects on marine mammals. During the 30-day public comment period, NMFS received six comment letters from the following: the Marine Mammal Commission (MMC); Ocean Conservancy and Oceana; the Alaska Eskimo Whaling Commission (AEWC); the Inupiat Community of the Arctic Slope (ICAS); the North Slope Borough (NSB) Office of the Mayor and NSB Department of Wildlife Management (collectively “NSB”); and Alaska Wilderness League (AWL), Center for Biological Diversity, Defenders of Wildlife, Earthjustice, Natural Resources Defense Council, Northern Alaska Environmental Center, Pacific Environment, Sierra Club, The Wilderness Society, and World Wildlife Fund (collectively “AWL”), along with an attached letter from David E. Bain, Ph.D.

Both AEWC and NSB submitted several journal articles as attachments to their comment letters. NMFS acknowledges receipt of these documents but does not intend to address the specific articles themselves in the responses to comments. AEWC also submitted an unsigned, final version of the 2009 Conflict Avoidance Agreement (CAA). However, Shell signed the CAA on June 24, 2009. Some of NSB's comments were specific to the application and do not have a bearing on NMFS' determinations for issuing an IHA. For example, NSB pointed out that Figure 1 in Shell's application failed to identify the Alaska Maritime National Wildlife Refuge north of Point Lay and asked that the figure be revised. Those comments have been passed on to Shell for consideration in future IHA applications. Any application specific comments that address the statutory and regulatory requirements or findings NMFS must make to issue an IHA are addressed in this section of the

Federal Register

notice. Additionally, some of NSB's comments concerned the Beaufort Sea operations or ice gouge surveys. As noted above and in the Notice of Proposed IHA (74 FR 26217, June 1, 2009), Shell notified NMFS that it did not intend to conduct these activities; therefore, no marine mammals will be taken. Comments on the Beaufort operations and Chukchi ice gouge survey are not addressed in this document.

General Comments

Comment 1:

AWL believes that NMFS should not issue incidental take authorizations for oil and gas-related seismic surveying until NMFS and other agencies complete a comprehensive review of both the industrial activities and the marine resources of the Arctic. This review should ensure that critical information gaps relating to the Arctic are filled and that decisions made about Arctic activities are made in the context of a comprehensive plan for the region. In the interim, NMFS should not facilitate further potentially harmful seismic activity.

Response:

In order to issue an authorization pursuant to Section 101(a)(5)(D) of the MMPA, NMFS must determine that the authorized activity will take only small numbers of marine mammals, will have a negligible impact on affected species or stocks, and will not have an unmitigable adverse impact on affected species or stocks for subsistence uses. If NMFS is able to make these findings, the Secretary is required to issue an IHA. In the case of Shell's activities for 2009/2010 (as described in the application, the Notice of Proposed IHA (74 FR 26217, June 1, 2009) and this document), NMFS determined that the authorized activity met the requirements of Section 101(a)(5)(D) of the MMPA. Additionally, as described later in this section and throughout this document, NMFS has determined that Shell's activities will not result in injury or mortality of marine mammals.

Comment 2:

AWL, ICAS, and Ocean Conservancy and Oceana note that Shell's activities will occur on leases that were acquired in OCS LS 193, which was conducted pursuant to MMS' 2007-2012 Five-Year Leasing Program. This leasing program is part of on-going litigation. NMFS should not issue IHAs for activities on these leases until the litigation is resolved.

Response:

NMFS is aware of the litigation in the U.S. Court of Appeals for the D.C. Circuit, but we disagree with the commenter's assertion that NMFS should not issue IHAs for activities on these leases until the litigation is resolved. Although the court issued an opinion vacating and remanding the 5-yr lease program to MMS, it also issued an order (on July 28, 2009) staying its mandate. MMS informed the court that it would complete remand proceedings as soon as possible and that, in the meantime, it would continue to review and act upon exploration plans for Chukchi Sea leases. MMS stated, however, that it would suspend activities under any approved plan pending the Secretary of the Interior's reconsideration decision on the remanded program, thereby halting all but data gathering ancillary activities on Chukchi Sea leases. Shell's 2009 operations are unaffected by the litigation because they are data gathering ancillary activities. Therefore, NMFS has concluded it was appropriate to issue an IHA to Shell for its 2009 seismic operations.

Comment 3:

ICAS points out that Native communities in Alaska have long been ignored in the race to find and develop offshore oil and gas resources and that the U.S. Government has consistently failed to comply with legal requirements that require consultation with local Native communities as proposals are being developed that affect native environments. Instead, both Federal agencies and the entities they permit make only token gestures at consultations with Native groups offering them only the opportunity for involvement after proposals are developed and after local knowledge would serve a useful purpose.

Response:

Regulations at 50 CFR 216.104(a)(12) require applicants for IHAs in Arctic waters to submit a Plan of Cooperation (POC), which, among other things, requires the applicant to meet with affected subsistence communities to discuss the proposed activities. Additionally, for many years, NMFS has conducted the Arctic Open-water Meeting, which brings together the Federal agencies, the oil and gas industry, and affected Alaska Native organizations to discuss the proposed activities and monitoring plans. Local knowledge is considered at these times, and it is not too late for that knowledge to serve a useful purpose.

Comment 4:

Executive Order 13175 requires Federal agencies to conduct government-to-government consultation when undertaking to formulate and implement policies that have tribal implications. Despite this explicit requirement, ICAS believes that NMFS has failed to consult with governing bodies of Native people who will be and have been affected by the decisions NMFS is making under the MMPA. NMFS must meet with ICAS and local Native villages on a government-to-government basis to discuss the proposed IHA, as well as appropriate mitigation and monitoring requirements.

Response:

NMFS recognizes the importance of the government-to-government relations and has taken steps to ensure that Alaska Natives play an active role in the management of Arctic species. For example, NOAA and the AEWC co-manage bowhead whales pursuant to a cooperative agreement. This agreement has allowed the AEWC to play a significant role in the management of a valuable resource by affording Alaska Natives the opportunity to protect bowhead whales and the Eskimo culture and to promote scientific investigation, among other purposes.

In addition, NMFS works closely with Alaska Natives when considering whether to permit the take of marine mammals incidental to oil and gas operations. NMFS has met repeatedly over the years with Alaska Native representatives to discuss concerns related to NMFS' MMPA program in the Arctic, and has also taken into account recommended mitigation measures to reduce the impact of oil and gas operations on bowhead whales and to ensure the availability of marine mammals for taking for subsistence uses. Finally, NMFS has participated in Alaska Native community meetings in the past and will continue to do so, when feasible. NMFS will continue to ensure that it meets its government-to-government responsibilities and will work closely with Alaska Natives to address their concerns.

Comment 5:

Ocean Conservancy and Oceana believe that Shell's activities could substantially affect marine mammals in an area already impacted by climate change and particularly vulnerable to ocean acidification. Approving an IHA in these circumstances would be contrary to NMFS' responsibilities under the law.

Response:

NMFS believes that it has made all of the necessary determinations in order to issue an IHA pursuant to Section 101(a)(5)(D) of the MMPA. NMFS has determined that Shell's activities will affect only small numbers of marine mammals, will have a negligible impact on the affected species and stocks, and will not have an unmitigable adverse impact on the availability of such species or stock for taking for subsistence purposes, provided the mitigation measures described later in this document are implemented. NMFS completed an EA to analyze the impacts of cumulative activities on the affected species in the action area, including climate change.

Comment 6:

AEWC and NSB expressed three concerns with the timing of IHA applications. First, they ask that only one authorization be issued per calendar year or per operating season for work associated with a specific project. Secondly, NMFS should ensure that IHA applications are submitted at least 1 month prior to the April Open-water Meeting or comparable peer review meetings that may ultimately replace such meetings. This will allow Native communities to receive draft POCs and proposed mitigation measures sufficiently in advance of these meetings to allow for meaningful discussion of any identified major flaws, evaluation of suggested improvements that draw upon our particular local expertise, and consideration of appropriate peer reviewers. Lastly, they request that NMFS change the expiration date for authorizations so that a single calendar year is authorized rather than activities in the latter part of one calendar year and the early part of the following year.

Response:

Regarding the first and third points, Section 101(a)(5)(D) of the MMPA allows NMFS to issue IHAs “for periods of not more than 1 year.” There is no requirement that the period of effectiveness of an IHA fall within 1 calendar year or operating season. In instances where the period of effectiveness of an IHA would cover more than one operating season (i.e., there is considerable downtime between the start and finish of the operations), NMFS analyzes impacts for the entire extent of the operations when issuing the IHA. Regarding the second point about distribution of applications, NMFS cannot guarantee that all applications will be submitted to NMFS at least 1 month prior to the meeting. NMFS has a unique relationship with AEWC pursuant to a cooperative agreement. Pursuant to this agreement, NOAA is required to consult with AEWC on any action undertaken or proposed to be undertaken that may affect the bowhead whale and/or subsistence whaling. To that end, NMFS will make every effort to provide the AEWC with as much information as possible prior to the Open-water Meeting or comparable peer review meeting. However, it is NMFS' practice not to release applications for MMPA authorizations until NMFS deems them complete and a proposed IHA notice or notice of receipt of an application for rulemaking has published in the

Federal Register

.

Comment 7:

NSB notes that Shell's application indicates that several vessels will be involved in the 2009-2010 period, involving various transit routes that are to be used to reach the Arctic survey sites. There is an absence of discussion of impacts and “takes” that may occur upon these transit routes. Shell needs to consider and state the impacts sufficiently. Additionally, Shell should consider other stocks of belugas beyond the Beaufort and Chukchi sea stocks, as impacts may occur in Bristol Bay during ship transit.

Response:

As has been stated in several

Federal Register

notices in the past, normal shipping and transit operations do not rise to a level requiring an authorization under the MMPA. To require IHAs and Letters of Authorization (LOAs) for standard shipping would reduce the ability of NMFS to review activities that have a potential to cause harm to marine mammal populations. For example, in the Arctic Ocean, NMFS would need to issue authorizations for barging operations that supply the North Slope villages in addition to various onshore and offshore oil and gas projects. However, on this matter, Shell will (in keeping with the CAA signed by Shell) follow transit routes contained in the CAA to avoid conflicts with subsistence hunters.

Comment 8:

NSB states that NMFS should not issue Shell an IHA for the strudel scour surveys in 2010, as they are substantially different from the shallow hazards and site clearance surveys. Additionally, it is not clear what other activities might be occurring in 2010, so it is not possible to evaluate the potential cumulative impacts from multiple activities that might occur in 2010. If NMFS does issue Shell an IHA for that survey, estimated takes and monitoring are needed. Additional information is needed from Shell about the possible impacts to marine mammals, monitoring plans, and mitigation measures from helicopter surveys over the sea ice. NMFS needs to make this additional information available to the public and decision makers for review and comment before it issues an IHA to Shell for strudel scour surveys in 2010. NSB also notes that the number of days of operation for

the strudel scour surveys is not consistent throughout the application.

Response:

The activities for the strudel scour survey are described in Shell's application and the proposed IHA in order to describe the full scale of Shell's operations. However, NMFS has determined that the activities for the strudel scour survey will not result in take of marine mammals. While the sonar equipment proposed to be used for this project generates high sound energy, the equipment operates at frequencies (>100 kHz) beyond the effective hearing range of most marine mammals likely to be encountered during strudel scour operations. Given the direct downward beam pattern of these sonar systems coupled with the high-frequency characteristics of the signals, the horizontal received levels of 180 and 190 dB re 1 μPa (rms) would be much smaller when compared to those from the low-frequency airguns with similar source levels. Therefore, NMFS has determined that marine mammals will not have a significant behavioral response (i.e., a “take”) to the strudel scour surveys. However, Shell needs to coordinate these activities with the Native Alaskan communities to ensure that there is no unmitigable adverse impact to subsistence hunts. As described in the application, two separate activities will occur to complete the strudel scour surveys: helicopter overflights and marine vessel work. The overflights will take approximately 4 days to complete and will occur in mid-May or early June. The marine vessel portion of the survey will take approximately 10 days to complete and will occur sometime in July or early to mid-August.

Comment 9:

NSB incorporated by reference a December 18, 2008, letter sent to the Acting Assistant Administrator for Fisheries, as well as NMFS' February 19, 2009, response, asking for suspension and review of Shell's 2008-2009 IHA, wherein Shell was allowed to proceed with seismic activities despite what was acknowledged by NMFS to be a potentially flawed survey design. At that time, NSB asked that no more IHAs be issued until compliance with the MMPA could be demonstrated. Based on NSB's review of NMFS' current proposed IHA, NSB does not see a demonstration of compliance and thus does not support issuance of an IHA at this time.

Response:

As was stated in NMFS' February letter responding to NSB's concerns, NMFS determined that Shell was in substantial compliance with their IHA during the 2008 seismic survey season. No additional information has been provided to NMFS to indicate that Shell was not in compliance with the IHA. Additionally, NMFS believes that Shell will comply with the monitoring and mitigation measures required in the 2009 IHA.

MMPA Concerns

Comment 10:

AWL, NSB, and AEWC state that NMFS cannot issue an IHA or a LOA (because NMFS has not promulgated regulations for mortality by seismic activities) to Shell for its activities since they carry the potential for serious injury or death to marine mammals. AEWC also believes that because Level A harassment is possible, an LOA is needed.

Response:

Section 101(a)(5)(D) of the MMPA authorizes Level A (injury) harassment and Level B (behavioral) harassment takes. While NMFS' regulations indicate that a LOA must be issued if there is a potential for serious injury or mortality, NMFS does not believe that Shell's surveys will result in serious injury or mortality, thus obviating the need for a LOA. As explained throughout this

Federal Register

Notice, it is highly unlikely that marine mammals would be exposed to sound pressure levels (SPLs) that could result in serious injury or mortality. The best scientific information indicates that an auditory injury is unlikely to occur as apparently sounds need to be significantly greater than 180 dB for injury to occur (Southall

et al.

, 2007). Based on the analysis contained in the “Potential Effects of Survey Activities on Marine Mammals” section in the Notice of Proposed IHA (74 FR 26217, June 1, 2009), NMFS has determined that an IHA can lawfully be issued to Shell for their activities since the already unlikely potential for serious injury or mortality will be reduced even further through the incorporation of the mitigation and monitoring measures described later in this document and required by the IHA.

Comment 11:

AEWC notes their disappointment in NMFS for releasing for public comment an incomplete application from Shell that fails to provide the mandatory information required by the MMPA and NMFS' implementing regulations. AEWC requests that NMFS return Shell's application as incomplete, or else the agency risks making arbitrary and indefensible determinations under the MMPA. The following is the information that AEWC believes to be missing from Shell's application: (1) a POC “or information that identifies what measures have been taken and/or will be taken to minimize any adverse effects on the availability of marine mammals for subsistence uses” (50 CFR 216.104(a)(12)); (2) a scheduled meeting “with the affected subsistence communities to discuss proposed activities and to resolve potential conflicts” (50 CFR 216.104(a)(12)(ii)); (3) a “description of what measures the applicant has taken and/or will take to ensure that proposed activities will not interfere with subsistence whaling or sealing” (50 CFR 216.104(a)(12)(iii)); (4) suggested means of learning of, encouraging, and coordinating any research related activities (50 CFR 216.104(a)(14)); (5) a description of the specified activities and specified geographic region (16 U.S.C. 1371(a)(5)(D)(i)); and (6) a description of the “age, sex, and reproductive condition” of the marine mammals that will be impacted (50 CFR 216.104(a)(6)). AWL and NSB also note their concern about the lack of specificity regarding the timing and location of the site clearance and shallow hazards and strudel scour surveys.

Response:

NMFS does not agree that it released an incomplete application for review during the public comment period. After NMFS' initial review of the application, NMFS submitted questions and comments to Shell on its application. After receipt and review of Shell's responses, which were submitted as an addendum to the original application, NMFS made its determination of completeness and released the application, addenda, and the proposed IHA notice (74 FR 26217, June 1, 2009). Regarding the six specific pieces of information believed to be missing by AEWC, Shell's original application included a description of the pieces of information that are required pursuant to 50 CFR 216.104(a)(12). The application noted that Shell was planning to meet with subsistence communities in 2009 and described measures to ensure that the applicant's proposed activities will not interfere with subsistence whaling or sealing. The proposed IHA notice (74 FR 26217, June 1, 2009) also noted meetings that had already taken place in the villages of Barrow, Point Hope, Point Lay, Wainwright, and Kotzebue. Moreover, on May 15, 2009, Shell distributed its draft POC for the 2009 activities to NMFS, other government agencies, and affected stakeholder communities.

Information required pursuant to 50 CFR 216.104(a)(14) was also included in Shell's application. Shell provided a list of researchers who could potentially receive results of their research activities who may find the data useful in their own research. Additionally, Shell and ConocoPhillips will be

working together in 2009 to deploy an intensive array of acoustic recorders around both the Burger and Klondike prospects in the Chukchi Sea.

NMFS also determined that Shell's application provides descriptions of the specified activities and specified geographic region. NMFS defines “specified geographical region” as “an area within which a specified activity is conducted and which has certain biogeographic characteristics” (50 CFR 216.103). In regard to how specific one must be to define a “specific geographic region” within which the activity would take place, House Report 97-228 states:

The specified geographic region should not be larger than is necessary to accomplish the specified activity, and should be drawn in such a way that the effects on marine mammals in the region are substantially the same. Thus, for example, it would be inappropriate to identify the entire Pacific coast of the North American continent as a specified geographic region, but it may be appropriate to identify particular segments of that coast having similar characteristics, both biological and otherwise, as specified geographical regions.

NMFS believes that the U.S. Chukchi Sea meets Congressional intent and NMFS' definition because the region has similar geographic, physiographic (e.g., topography, temperature, sea ice), biologic (e.g., marine fauna (fish and marine mammals)), and sociocultural characteristics. Shell's application noted that the applicant would conduct activities on some of its prospects gained during LS 193, which itself is considered a “specified geographic region.” Since that time, Shell has informed NMFS of the specific areas within the lease holdings on which Shell intends to conduct the site clearance and shallow hazards surveys. They are the Burger and Crackerjack prospects, as well as SW Shoebill if time and weather conditions allow. At this time, more specificity on the location of the in-water portion of the strudel scour surveys cannot be provided. Until areas with strudel scour are revealed during helicopter overflights, it is uncertain the exact location along the Chukchi Sea coast where marine vessel operations will occur. However, as previously mentioned, the Chukchi Sea itself is considered a “specified geographic region.” Shell also provided a description of the types of equipment that would be used and time frame for conducting its activities. Therefore, NMFS believes that Shell's description of the activity and the locations for conducting their surveys meet the requirements of the MMPA.

Lastly, 50 CFR 216.104(a)(6) requires that an applicant submit information on the “age, sex, and reproductive condition (

if possible

)” (emphasis added) of the number of marine mammals that may be taken. In the application, Shell described the species expected to be taken by harassment and provided estimates of how many of each species were expected to be taken during their activities. In most cases, it is very difficult to estimate how many animals, especially cetaceans, of each age, sex, and reproductive condition will be taken or impacted by seismic or site clearance and shallow hazards surveys. In conclusion, NMFS believes that Shell provided all of the necessary information to proceed with publishing a proposed IHA notice in the

Federal Register

.

Comment 12:

AEWC and NSB state that Shell did not disclose the full spectrum of activities in which it will engage. For example, Shell mentions support vessels and other equipment in its application but such machinery is not disclosed among Shell's activities. Additionally, Shell changed the airgun array it planned to use after submitting its application but did not conduct any new analysis of the impacts from this change, thus negating its analysis of the impacts from the original airgun array. Shell needs to adequately specify the activities and impacts of all the actions that will be undertaken in the Chukchi. AEWC also states that NMFS relied on surveys conducted in 2008 by Shell to calculate the area of “water exposed to received levels at or above 160 dB.” The 2008 surveys, however, were based on signals from “four 10 in

3

airguns,” and not the 40 in

3

airguns that Shell now intends to use. Thus, for this reason as well, Shell's application must be returned.

Response:

NMFS determined that Shell's application and application addenda fully described the activities in which Shell will engage. In previous years, when Shell conducted its larger, 3D seismic surveys, several support vessels were needed to carry out operations. However, for this smaller survey, all work will be conducted from the single source vessel. All acoustic equipment that will be used to conduct the surveys is listed in the application. Shell did change the number of airguns and submitted this information to NMFS in their second application addendum. In assessing the new airgun array, NMFS determined that the potential impacts to marine mammals would be the same if the total discharge volume was 20 in

3

or 40 in

3

. Shell submitted revised take estimates based on the new discharge volume and ensonified zones. The analysis of impacts from airguns and the revised take estimates were contained in the proposed IHA notice (74 FR 26217, June 1, 2009). Therefore, NMFS determined that Shell adequately specified the activities and impacts of all the actions that will be undertaken in the Chukchi Sea.

The modeled radii that Shell submitted were from sound source verification tests conducted in the Chukchi Sea during the 2008 open-water season by JASCO. JASCO modeled three different airgun configurations: 4 x 10 in

3

airgun array; 2 x 10 in

3

airgun array; and 1 x 10 in

3

airgun. For 2009, Shell intends to use the 4 x 10 in

3

airgun array and not the 40 in

3

airguns, as noted by AEWC. Therefore, this modeling was accurately used by Shell in its submission to NMFS.

Comment 13:

NSB and AWL expressed concern that the IHA will cover a full year, as the assessment of effects on bowhead whales apparently relies in part on the surveys ending before the peak of the bowhead fall migration through the Chukchi Sea. Shell indicates that it will require a maximum of 50 days of active data acquisition, but it is noteworthy that this estimate expressly excludes any unplanned downtime. Consequently, Shell could need to survey well into the month of October, and the IHA as proposed would allow it to do so. A 1-year IHA is clearly not compelled by the MMPA, and an authorization that includes a portion of the next open-water season only invites later confusion. Although NMFS' analysis of impacts to marine mammals appears to consider the entire 50 days of active surveying, the process leaves open the possibility of an unjustifiably segmented evaluation of survey activity, looking only at a portion of the surveying that will take place in a single season. NMFS should take steps to avoid such results.

Response:

Section 101(a)(5)(D)(i) of the MMPA states that: “Upon request therefor by citizens of the United States who engage in a specified activity (other than commercial fishing) within a specific geographic region, the Secretary shall authorize, for periods of not more than 1 year, subject to such conditions as the Secretary may specify, the incidental, but not intentional, taking by harassment of small numbers of marine mammals of a species or population stock by such citizens while engaging in that activity within that region....”

As noted, the MMPA does not limit the issuance of an IHA to a single open-water season (approximately July 20 to approximately November 15 in the U.S. Beaufort and Chukchi Seas), a period of less than 4 months, and even less

available time if an applicant's activity is located in an area subject to area closure due to native subsistence hunting. Provided the IHA application includes an analysis of the specified activities during the time frame proposed by the applicant, NMFS will consider issuing an IHA that extends into a portion of the following year. NMFS evaluated the effects of Shell's activities for the full requested time frame, including evaluating effects into the following season. Additionally, NMFS believes that even if Shell must conduct activities into the middle or end of October, the mitigation and monitoring measures required by the IHA (described later in this document) will not increase the level of impact to marine mammals in the area.

Comment 14:

AEWC and NSB state that NMFS failed to issue a draft authorization for public review and comment. The plain language of both the MMPA and NMFS' implementing regulations require that NMFS provide the opportunity for public comment on the “proposed incidental harassment authorization” (50 CFR 216.104(b)(1)(i); 16 U.S.C. 1371 (a)(5)(D)(iii)) and not just on the application itself as NMFS has done here. Without a complete draft authorization and accompanying findings, AEWC and NSB cannot provide meaningful comments on Shell's proposed activities, ways to mitigate the impacts of those activities on marine mammals, and measures that are necessary to protect subsistence uses and sensitive resources. For example, AEWC cannot ensure that the authorization will comport with the requirements of the applicable CAA.

Response:

The June 1, 2009 proposed IHA notice (74 FR 26217) contained all of the relevant information needed by the public to provide comments on the proposed authorization itself. The notice contained the permissible methods of taking by harassment, means of effecting the least practicable impact on such species (i.e., mitigation), measures to ensure no unmitigable adverse impact on the availability of the species or stock for taking for subsistence use, requirements pertaining to the monitoring and reporting of such taking, including requirements for the independent peer review of the proposed monitoring plan. The notice provided detail on all of these points, allowing the public to provide meaningful comments. Additionally, the notice contained NMFS' preliminary findings of negligible impact and no unmitigable adverse impact.

The signing of a CAA is not a requirement to obtain an IHA. Additionally, the CAA is a document that is negotiated between and signed by the industry participant, AEWC, and the Village Whaling Captains' Associations. NMFS has no role in the development or execution (other than, where appropriate, to include marine mammal-related measures from the CAA in the IHA) of this agreement. While signing a CAA helps NMFS to make its no unmitigable adverse impact determination for bowhead and beluga whales, it is not a requirement.

Comment 15:

NSB states that based on the limited information provided by NMFS, there is no way to determine whether Shell's monitoring and reporting plans were subjected to independent peer review, as required by the MMPA. Unless NMFS can demonstrate compliance with the MMPA and its own regulations, it cannot issue an IHA to Shell. AEWC also notes that NMFS cannot issue an IHA to any company whose monitoring plan has not been cleared through independent peer review.

Response:

On May 6, 2009, NMFS contacted representatives from AEWC, NSB, MMC, and Shell about nominating people to participate in an independent peer review of Shell's monitoring plan. NMFS received nominations from all of the contacted parties and selected and contacted reviewers from these lists. Two of the contacted individuals provided detailed comments on Shell's monitoring and reporting plan. NMFS provided Shell with the comments and recommendations of the reviewers. The reviewers' comments and changes to the monitoring plan are addressed later in this document (see “Monitoring Plan Independent Peer Review” section later in this document). NMFS complied with the requirements under the MMPA and the implementing regulations for issuing IHAs, and therefore can legally issue an IHA to Shell to conduct their operations.

Comment 16:

AEWC states that because of the critical information provided through the direct observations of AEWC hunters, the peer review process must include AEWC representatives.

Response:

NMFS' proposed rule for implementing the 1994 amendments to the MMPA described the process for conducting an independent peer review of monitoring plans where the proposed activity may affect the availability of a species or stock for taking for subsistence uses (60 FR 28379, May 31, 1995). While panelists for the independent peer review are selected by NMFS in consultation with the MMC, AEWC and/or other Alaska native organizations as appropriate, and the applicant, selected “panelists are experts who are not currently employed or contracted by either the affected Alaskan native organization or the applicant” (60 FR 28381, May 31, 1995). Therefore, it was NMFS' intent not to include AEWC representatives in the independent peer review process. However, AEWC representatives are afforded the opportunity to provide information based on their direct observations and experiences at the annual Open-water Meeting and through the public comment process on the proposed IHA.

Comment 17:

AEWC specifically requests that NMFS release its response to comments at the earliest possible time and that NMFS not allow seismic activities to begin until the whaling captains have had a chance to review NMFS' response. We note that in 2008, NMFS did not publish its response to comments on Shell's IHA for seismic operations in the Beaufort Sea until well after the fall subsistence hunt at Cross Island had concluded and seismic operations had already taken place. There can be no excuse for allowing seismic operations to take place directly within one of the most important subsistence hunting areas in the Arctic Ocean prior to NMFS explaining to the local communities and whaling captains why it was issuing an IHA over their well-reasoned objections, which were presented during the public comment period. The fact that NMFS would not release its response to comments until after the activities had taken place casts serious doubt on the validity of NMFS' public involvement process and the underlying analysis of impacts to subsistence activities and marine mammals.

Response:

NMFS publishes its responses to public comments in the

Federal Register

notice of issuance or denial. There is no provision requiring an applicant to wait to begin operations until after review of NMFS' responses to comments by members of the public. No public comment period is required on the

Federal Register

notice announcing NMFS' final decision. For the issuance of Shell's 2008 and 2009 IHAs, NMFS reviewed and considered all of the comments submitted before making its final determinations. Additionally, NMFS summarized and presented all of the significant issues raised by the commenters to the decision maker before signing the IHA.

Comment 18:

AEWC notes that by regulation, Shell must include with its application a POC that ensures potential conflicts with subsistence uses are resolved/mitigated prior to the issuance of an IHA. It is AEWC's view that

signing and following the CAA meets the POC requirement as it pertains to bowhead whales. AEWC states that Shell must agree to all the terms of the 2009 Open-water CAA in order to mitigate the effects of its proposed operations. In fact, the CAA was in use prior to NMFS' issuance of its regulations, and the POC requirement was included in the regulatory language to point operators to the CAA. In addition to the CAA setting forth mitigation measures agreed to by the operators and hunters, a schedule of meetings in preparation for each upcoming season, and post-season review meetings to evaluate the effectiveness of mitigation measures employed during a certain season, an operator's adherence to the terms of the CAA enables the Secretary to make the no unmitigable adverse impact finding required by Congress in the MMPA. NMFS is well-advised to heed the long-standing practice of relying on the CAA to enable the Secretary to make the required finding, as the agency has no other basis upon which to determine whether a specified set of mitigation measures will enable hunters to retain access to migrating marine mammals without increasing the risks associated with an already high-risk practice.

Response:

NMFS believes that the CAA is an important mechanism to ensure that there is not an unmitigable adverse impact on the availability of bowhead whales for taking for subsistence uses. However, the CAA is a document entered into between two entities (industry applicants and native community stakeholders). NMFS is neither a signatory to the CAA, nor does it play any formal role in the development of the CAA other than by requiring industry applicants to develop a POC pursuant to 50 CFR 216.104(a)(12). Moreover, the CAA is only one way to make the no unmitigable adverse impact to subsistence uses finding. Although NMFS has a limited role in this process, NMFS supports the continuation of the CAA process to help ensure that native subsistence harvests are successful.

Comment 19:

AEWC and NSB state that the conclusion that Shell's proposed activities will only take small numbers of marine mammals and will have no more than a negligible impact is not justified by the information provided. AEWC believes that without knowing more about the status and number of species present in the Chukchi Sea, this conclusion cannot be supported. NSB believes that NMFS has not adequately considered whether marine mammals may be harassed at received levels significantly lower than 160 dB and has not considered the possible serious injuries associated with authorizing the proposed activities.

Response:

NMFS believes that it provided sufficient information in its proposed IHA notice (74 FR 26217, June 1, 2009) to make the small numbers and negligible impact determinations and that the best scientific information available was used to make those determinations. The available information was sufficient to make the necessary findings. While some published articles indicate that certain marine mammal species may avoid seismic vessels at levels below 160 dB, NMFS does not believe that these responses rise to the level of a significant behavioral response. While studies, such as Miller

et al.

(1999), have indicated that some bowhead whales may have started to be deflected from their migratory path 35 km (21.7 mi) from the seismic vessel, it should be pointed out that these minor course changes are during migration and, as described in MMS' 2006 Final Programmatic Environmental Assessment (PEA), have not been seen at other times of the year and during other activities. To show the contextual nature of this minor behavioral modification, recent monitoring studies of Canadian seismic operations indicate that feeding, non-migratory bowhead whales do not move away from a noise source at an SPL of 160 dB. Therefore, while bowheads may avoid an area of 20 km (12.4 mi) around a noise source, when that determination requires a post-survey computer analysis to find that bowheads have made a 1 or 2 degree course change, NMFS believes that does not rise to a level of a “take.” NMFS therefore continues to estimate “takings” under the MMPA from impulse noises, such as seismic, as being at a distance of 160 dB (re 1 μPa).

NMFS has determined that Shell's activities will not cause serious injury to marine mammals. As explained throughout this

Federal Register

Notice, it is highly unlikely that marine mammals would be exposed to SPLs that could result in serious injury or mortality. The best scientific information indicates that an auditory injury is unlikely to occur, as apparently sounds need to be significantly greater than 180 dB for injury to occur (Southall

et al.

, 2007). The 180-dB radius for the airgun array to be used by Shell is 160 m (525 ft). Therefore, if injury were possible from Shell's activities, the animal would need to be closer than 160 m (525 ft). However, based on the configuration of the airgun array and streamers, it is highly unlikely that a marine mammal would be that close to the seismic vessel. Mitigation measures described later in this document will be implemented should a marine mammal enter this small zone around the airgun array.

Comment 20:

AEWC notes that based on the density estimates, Shell is predicting that an average of 692 and a maximum of 1,078 ringed seals may be exposed to seismic sounds. These are by no means “small numbers” of marine mammals that will be subjected to impacts as a result of Shell's operations. NSB notes that Shell's application states that approximately 2 percent of the Bering-Chukchi-Beaufort stock of bowhead whales will be exposed to sounds greater than or equal to 160 dB (rms). This is a large percentage of the population.

Response:

NMFS determined that the small numbers requirement has been satisfied. Shell has predicted that an average of 692 ringed seals will be exposed to SPLs of 160 dB or greater during operations. This does not mean that this is the number of ringed seals that will actually exhibit a disruption of behavioral patterns in response to the sound source; rather, it is simply the best estimate of the number of animals that potentially could have a behavioral modification due to the noise. For example, Moulton and Lawson (2002) indicate that most pinnipeds exposed to seismic sounds lower than 170 dB do not visibly react to that sound, and, therefore, pinnipeds are not likely to react to seismic sounds unless they are greater than 170 dB re 1 μPa (rms).

The Level B harassment take estimate of 692 ringed seals is a small number, at least in relative terms, in that it represents only 0.3 percent of the regional stock size of that species (249,000), if each “exposure” at 160 dB represents an individual ringed seal. The percentage would be even lower if a higher SPL is required for a behavioral reaction (as is expected) or, if as expected, animals move out of the seismic area. As a result, NMFS determined that these “exposure” estimates are conservative, and seismic surveys will actually affect less than 0.3 percent of the Chukchi Sea ringed seal population.

Regarding bowhead whales, this percentage is a remnant from when Shell was going to conduct its full suite of surveys in both the Beaufort and Chukchi Seas. As mentioned earlier in this document, the Beaufort Sea surveys and the Chukchi Sea ice gouge survey were cancelled for the 2009/2010 season. Shell's Chukchi Sea site clearance and shallow hazards surveys are estimated to take only one bowhead whale, representing less than 0.01

percent of the Bering-Chukchi-Beaufort stock of bowhead whales.

Comment 21:

AEWC states that Shell should be required to engage in monitoring activities that are separate and apart from its oil and gas activities (see 50 CFR 216.104(a)(14)). These activities must be separate from Shell's proposed oil and gas related operations, since any data from such operations is skewed in light of marine mammals' avoidance of the vessels and seismic noise.

Response:

In 2009, Shell and ConocoPhillips are jointly funding an extensive acoustic monitoring program in the Chukchi Sea. A total of 44 recorders will be distributed both broadly across the Chukchi lease area and nearshore environment and intensively on the Burger and Klondike lease areas. The broad area arrays are designed to capture both general background soundscape data and marine mammal call data across the lease area. Shell hopes to gain insights into large-scale distribution of marine mammals, identification of marine mammal species present, movement and migration patterns, and general abundance data. Many of these recorders will be placed tens of miles away from the site clearance and shallow hazards surveys. Additionally, these recorders will remain deployed after completion of Shell's survey work in 2009.

Pursuant to 50 CFR 216.104(a)(14), an applicant must include “suggested means of learning of, encouraging, and coordinating research opportunities, plans, and activities relating to reducing such incidental taking and evaluating its effects.” There is no requirement that this information or monitoring be conducted separate and apart from the authorized activities, since the research is supposed to evaluate the effects of the taking.

Marine Mammal Impact Concerns

Comment 22:

AWL, NSB, and AEWC noted that NMFS has acknowledged that permanent threshold shift (PTS) qualifies as a serious injury. Therefore, if an acoustic source at its maximum level has the potential to cause PTS and thus lead to serious injury, it would not be appropriate to issue an IHA for the activity (60 FR 28381, May 31, 1995). AEWC states that therefore an LOA is required here. While the airguns proposed by Shell are smaller than those associated with typical 2D/3D deep marine surveys, the noise they produce is still considerable, as evidenced by the estimated 120 dB radius that extends out to 24 km (15 mi). These groups state that in the proposed IHA, NMFS did not rule out the possibility of animals incurring PTS (74 FR 26222, June 1, 2009). Although NMFS characterizes the possibility as unlikely, it nevertheless relies on mitigation measures, such as ramp-ups and exclusion zones, to “minimize” the “already-minimal” probability of PTS.

Response:

In the proposed rule implementing the process to apply for and obtain an IHA, NMFS stated that authorizations for harassment involving the “potential to injure” would be limited to only those that may involve non-serious injury (60 FR 28380, May 31, 1995). However, NMFS goes on to say that “if the review of an application for incidental harassment indicates there is a potential for serious injury or death, NMFS proposes that it would either (1) determine that the potential for serious injury can be negated through mitigation requirements that could be required under the authorization or (2) deny” (

Ibid

) the IHA and require the applicant to petition for regulations and LOA. As stated several times in this document and previous

Federal Register

notices for seismic activities, there is no empirical evidence that exposure to pulses of airgun sound can cause PTS in any marine mammal, even with large arrays of airguns (see Southall

et al.

, 2007). PTS is thought to occur several decibels above that inducing mild temporary threshold shift (TTS), the mildest form of hearing impairment (a non-injurious effect). NMFS (1995, 2000) concluded that cetaceans and pinnipeds should not be exposed to pulsed underwater noise at received levels exceeding, respectively, 180 and 190 dB re 1 μPa (rms). The established 180- and 190-dB re 1 μPa (rms) criteria are 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 later in this document, data that are now available imply that TTS is unlikely to occur unless bow-riding odontocetes are exposed to airgun pulses much stronger than 180 dB re 1 Pa rms (Southall

et al.

, 2007). Additionally, while the

Federal Register

notice cited by the commenters states that NMFS considered PTS to be a serious injury (60 FR 28380, May 31, 1995), our understanding of anthropogenic sound and the way it impacts marine mammals has evolved since then, and NMFS no longer considers PTS to be a serious injury. NMFS has defined “serious injury” in 50 CFR 216.3 as “...any injury that will likely result in mortality.” There are no data that suggest that PTS would be likely to result in mortality, especially the limited degree of PTS that could hypothetically be incurred through exposure of marine mammals to seismic airguns at the level and for the duration that are likely to occur in this action.

The extent of the 120-dB radius does not indicate that animals may be seriously injured. Additionally, NMFS has required monitoring and mitigation measures to negate the possibility of marine mammals being seriously injured as a result of Shell's activities. In the proposed IHA, NMFS determined that no cases of TTS are expected to result from Shell's activities. Based on this determination and the explanation provided here, PTS is also not expected. Therefore, an IHA is appropriate.

Comment 23:

AEWC and NSB state that research is increasingly showing that marine mammals may remain within dangerous distances of seismic operations rather than leave a valued resource such as a feeding ground (see Richardson, 2004). The International Whaling Commission (IWC) scientific committee has indicated that the lack of deflection by feeding whales in Camden Bay (during Shell seismic activities) likely shows that whales will tolerate and expose themselves to potentially harmful levels of sound when needing to perform a biologically vital activity, such as feeding (mating, giving birth, etc.). Thus, the noise from Shell's proposed operations could injure marine mammals if they are close enough to the source.

Response:

If marine mammals, such as bowhead whales, remain near a seismic operation to perform a biologically vital activity, such as feeding, depending on the distance from the vessel and the size of the 160-dB radius, the animals may experience some Level B harassment. Depending on the distance of the animals from the vessel and the number of individual whales present, certain mitigation measures are required to be implemented. If an aggregation of 12 or more mysticete whales are detected within the 160-dB radius, then the airguns must be shutdown until the aggregation is no longer within that radius. Additionally, if any whales are sighted within the 180-dB radius of the active airgun array, then either a power-down or shutdown must be implemented immediately. For the reasons stated throughout this document, NMFS has determined that Shell's operations will not injure marine mammals.

Comment 24:

AWL and NSB state that the standard for determining whether an IHA is appropriate is exceptionally protective. If there is even the possibility of serious injury, NMFS must establish that the “potential for serious injury can be negated through mitigation requirements” (60 FR 28380, May 31, 1995; emphasis added). Reports from previous surveys, however, indicate that, despite monitored exclusion zones, marine mammals routinely stray too close to the airguns. AEWC states that the safety radii proposed by Shell do not negate injury.

Perhaps, more importantly, the documented exposures were recorded only because conditions were such that the marine mammals could be observed, but this only represents a fraction of the time that airguns are operating. Marine mammal observers (MMOs) cannot see animals at the surface when it is dark or during the day because of fog, glare, rough seas, the small size of animals such as seals, and the large portion of time that animals spend submerged. Shell has acknowledged that reported sightings are only “minimum” estimates of the number of animals potentially affected by surveying. AWL, NSB, and AEWC note that although NMFS recognizes that infra-red goggles and night-vision binoculars are of “limited” effectiveness when visibility is low, its only response for Shell's 2009 surveying is that MMOs are relieved of monitoring the exclusion zones at night, except during periods before and during ramp-ups.

NMFS appears to simply presume that marine mammals will naturally avoid airguns when they are operating at full strength, removing the need for monitoring when conditions prevent MMOs from effectively watching for intrusions into the exclusion zones. That premise is not supported by the survey data, indicating that shutdowns and power-downs have repeatedly proven necessary. The requirement for ramp-up rests on the same foundation that marine mammals will leave an affected area as a result of increasing noise. Yet, as the Joint Subcommittee on Ocean Science & Technology report noted, although ramp-up is a widely imposed practice, “there has never been a demonstration that it works as intended.” Because NMFS has not negated the possibility of serious injury from Shell's 2009 seismic surveying, it may not issue an IHA.

Response:

As has already been stated several times in this document, recent literature has indicated that sounds need to be significantly higher than 180 dB to cause injury to marine mammals (see Southall

et al.

, 2007). Therefore, the 180- and 190-dB safety zones are conservative. The survey reports indicate that mitigation measures (i.e., power-downs or shutdowns) were implemented, thus preventing the animals from being exposed to more than one or two seismic pulses. Additionally, Shell's operations will occur in an area where periods of darkness do not begin until early September. Beginning in early September, there will be approximately 1-3 hours of darkness each day, with periods of darkness increasing by about 30 min each day. By the end of the survey period, there will be approximately 8 hours of darkness each day.

The source vessel will be traveling at speeds of about 1-5 knots (1.9-9.3 km/hr). With a 180-dB safety range of 160 m (525 ft), the vessel will have moved out of the safety zone within a few minutes. As a result, during underway survey operations, MMOs are instructed to concentrate on the area ahead of the vessel, not behind the vessel where marine mammals would need to be voluntarily swimming towards the vessel to enter the 180-dB zone. In fact, in some of NMFS' IHAs issued for scientific seismic operations, shutdown is not required for marine mammals that approach the vessel from the side or stern in order to ride the bow wave or rub on the seismic streamers deployed from the stern (and near the airgun array) as some scientists consider this a voluntary action on the part of an animal that is not being harassed or injured by seismic noise. While NMFS concurs that shutdowns are not likely warranted for these voluntary approaches, in the Arctic Ocean, all seismic surveys are shutdown or powered down for all marine mammal close approaches. Also, in all seismic IHAs, including Shell's IHA, NMFS requires that the safety zone be monitored for 30 min prior to beginning ramp-up to ensure that no marine mammals are present within the safety zones. Implementation of ramp-up is required because it is presumed it would allow marine mammals to become aware of the approaching vessel and move away from the noise, if they find the noise annoying. Data from 2007 and 2008, when Shell had support boats positioned 1 km (0.62 mi) on each side of the 3D seismic vessel, suggest that marine mammals do in fact move away from an active source vessel. In those instances, more seals were seen from the support vessels than were seen from the source vessels during active seismic operations. Additionally, research has indicated that some species tend to avoid areas of active seismic operations (e.g., bowhead whales, see Richardson

et al.

, 1999).

NMFS has determined that an IHA is the proper authorization required to cover Shell's survey. As described in other responses to comments in this document, NMFS does not believe that there is a risk of serious injury or mortality from these activities. The monitoring reports from 2006, 2007, and 2008 do not note any instances of serious injury or mortality (Patterson

et al.

, 2007; Funk

et al.

, 2008; Ireland

et al.

, 2009). Additionally, NMFS is confident it has met all of the requirements of section 101(a)(5)(D) of the MMPA (as described throughout this document) and therefore can issue an IHA to Shell for its survey operations in 2009/2010.

Comment 25:

AWL, Dr. Bain, NSB, and AEWC believe that NMFS has not adequately considered whether marine mammals may be harassed at received levels significantly lower than 160 dB. Here, NMFS calculated harassment from Shell's proposed surveying based on the exposure to marine mammals to sounds at or above 160 dB. This uniform approach to harassment, however, does not take into account known reactions of marine mammals in the Arctic to levels of noise far below 160 dB. These letters state that bowhead, gray, killer, and beluga whales and harbor porpoise react to sounds lower than 160 dB. At least in the case of bowhead whales, a 120-dB level is more appropriate to assess levels of harassment.

Citing several papers on killer whales and harbor porpoise, Dr. Bain states that major behavioral changes of these animals appear to be associated with received levels of around 135 dB re 1 μPa, and that minor behavioral changes can occur at received levels from 90-110 dB re 1 μPa or lower. He also states that belugas have been observed to respond to icebreakers by swimming rapidly away at distances up to 80 km, where received levels were between 94 and 105 dB re 1 μPa. Belugas exhibited minor behavioral changes such as changes in vocalization, dive patterns, and group composition at distances up to 50 km (NRC, 2003), where received levels were likely around 120 dB.

AEWC also states that in conducting scoping on its national acoustic guidelines for marine mammals, NMFS noted that the existing system for determining take (i.e., the 160 dB mark) “considers only the sound pressure level of an exposure but not its other attributes, such as duration, frequency, or repetition rate, all of which are critical for assessing impacts on marine mammals” and “also assumes a

consistent relationship between rms (root-mean-square) and peak pressure values for impulse sounds, which is known to be inaccurate under certain (many) conditions” (70 FR 1871, 1873, January 11, 2005). Thus, NMFS itself has recognized that 160 dB (rms) is not an adequate measure.

Response:

The best information available to date for reactions by bowhead whales to noise, such as seismic, is based on the results from the 1998 aerial survey (as supplemented by data from earlier years) as reported in Miller

et al.

(1999). In 1998, bowhead whales below the water surface at a distance of 20 km (12.4 mi) from an airgun array received pulses of about 117-135 dB re 1 μPa rms, depending upon propagation. Corresponding levels at 30 km (18.6 mi) were about 107-126 dB re 1 Pa rms. Miller

et al.

(1999) surmise that deflection may have begun about 35 km (21.7 mi) to the east of the seismic operations, but did not provide SPL measurements to that distance and noted that sound propagation has not been studied as extensively eastward in the alongshore direction, as it has northward, in the offshore direction. Therefore, while this single year of data analysis indicates that bowhead whales may make minor deflections in swimming direction at a distance of 30-35 km (18.6-21.7 mi), there is no indication that the SPL where deflection first begins is at 120 dB, it could be at another SPL lower or higher than 120 dB. Miller

et al.

(1999) also note that the received levels at 20-30 km (12.4-18.6 mi) were considerably lower in 1998 than have previously been shown to elicit avoidance in bowheads exposed to seismic pulses. However, the seismic airgun array used in 1998 was larger than the ones used in 1996 and 1997. Therefore, NMFS believes that it cannot scientifically support adopting any single SPL value below 160 dB and apply it across the board for all species and in all circumstances. Second, these minor course changes occurred during migration and, as indicated in MMS' 2006 PEA, have not been seen at other times of the year and during other activities.

Third, as stated in the past, NMFS does not believe that minor course corrections during a migration rise to a level of being a significant behavioral response. To show the contextual nature of this minor behavioral modification, recent monitoring studies of Canadian seismic operations indicate that when, not migrating, but involved in feeding, bowhead whales do not move away from a noise source at an SPL of 160 dB. Therefore, while bowheads may avoid an area of 20 km (12.4 mi) around a noise source, when that determination requires a post-survey computer analysis to find that bowheads have made a 1 or 2 degree course change, NMFS believes that does not rise to a level of a “take.” NMFS therefore continues to estimate “takings” under the MMPA from impulse noises, such as seismic, as being at a distance of 160 dB (re 1 Pa). However, monitoring a 120-dB radius in the Chukchi Sea is not practicable and due to safety concerns, NMFS would not require this level of monitoring in the Chukchi Sea.

Although it is possible that marine mammals could react to any sound levels detectable above the ambient noise level within the animals' respective frequency response range, this does not mean that such animals would react in a biologically significant way. According to experts on marine mammal behavior, the degree of reaction which constitutes a “take,” i.e., a reaction deemed to be biologically significant that could potentially disrupt the migration, breathing, nursing, breeding, feeding, or sheltering, etc., of a marine mammal is complex and context specific, and it depends on several variables in addition to the received level of the sound by the animals. These additional variables include, but are not limited to, other source characteristics (such as frequency range, duty cycle, continuous vs. impulse vs. intermittent sounds, duration, moving vs. stationary sources, etc.); specific species, populations, and/or stocks; prior experience of the animals (naive vs. previously exposed); habituation or sensitization of the sound by the animals; and behavior context (whether the animal perceives the sound as predatory or simply annoyance), etc. (Southall

et al.

, 2007).

The references cited in the comment letters address different source characteristics (continuous sound rather than impulse sound that are planned for the proposed shallow hazard and site clearance surveys) or species (killer whales and harbor proposes) that rarely occur in the proposed Arctic action area. Much research regarding bowhead and gray whales response to seismic survey noises has been conducted in addition to marine mammal monitoring studies during prior seismic surveys. Detailed descriptions regarding behavior responses of these marine mammals to seismic sounds are available (e.g., Richardson

et al.

, 1995; review by Southall

et al.

, 2007), and are also discussed in this document. Additionally, as Shell does not intend to use ice-breakers during its operations, statements regarding beluga reactions to icebreaker noise are not relevant to this activity.

Regarding the last point raised in this comment by AEWC, NMFS recognizes the concern. Based on the information and data contained in Southall

et al.

(2007), NMFS is moving towards implementing a dual criteria for impacts of noise on marine mammals. However, until guidelines are available, NMFS will continue to use the 160-dB threshold for determining the level of take of marine mammals by Level B harassment for impulse noise (such as from airguns).

Comment 26:

NSB and AWL note that this IHA, as currently proposed, is based on uncertainties that are not allowed under the MMPA. Citing comments made by NMFS on recent MMS LS Environmental Impact Statements, they note that NMFS stated that without more current and thorough data on the marine mammals in the Chukchi Sea and their use of these waters, it would be difficult to make the findings required by the MMPA. NMFS also specifically observed that activities “occurring near productive forage areas such as the Hanna Shoal” or “along migratory corridors” are most likely to encounter and impact marine mammals. Shell's proposed surveying for 2009 will likely take place proximate to the Hanna Shoal and within the pathway for migrating bowheads.

It is generally recognized that there is much unknown about the range of potential effects of sound on marine mammals, especially long-term sublethal effects and the impact of exposure to increasing levels of noise year after year. NMFS noted in both sets of LS comments that the “continued lack of basic audiometric data for key marine mammal species” that occur throughout the Chukchi Sea inhibits the “ability to determine the nature and biological significance of exposure to various levels of both continuous and impulsive oil and gas activity sounds.” Again, NMFS stressed that additional data should be obtained for the agency to consider authorizing incidental taking under the MMPA and the Endangered Species Act (ESA). AWL also states that the need for more information regarding the effects of sound and the appropriate mitigation measures was emphasized in a recent report issued by an interagency task force led by a representative from NOAA (JSOST, 2009). This lack of information runs up against the precautionary nature of the MMPA. Nor can NMFS claim the lack of available information justifies its decision. NMFS has an affirmative obligation to find that impacts are no more than “negligible”

and limited to the harassment of only “small numbers of marine mammals.”

NSB also notes that Shell's application contains several references to the lack of evidence for damage to auditory mechanisms of several marine mammals. A lack of data does not amount to a lack of evidence. Shell needs to provide actual citations that show a lack of damage. These citations must be from studies of baleen whales, belugas, and pinnipeds that were focused on the assessment of this type of damage. But this information does not exist for the noise produced typical of Arctic open-water seismic operations. In fact, the basic anatomy of bowhead whale auditory apparatus has not been investigated.

Response:

NMFS agrees that there is some uncertainty on the current status of some marine mammal species in the Chukchi Sea and on impacts to marine mammals from seismic surveys. NMFS is currently proposing to conduct new population assessments for Arctic pinniped species, and current information is available on-line through the Stock Assessment Reports (SARs). In regard to impacts, there is no indication that seismic survey activities are having a long-term impact on marine mammals. For example, apparently, bowhead whales continued to increase in abundance during periods of intense seismic in the Chukchi Sea in the 1980s (Raftery

et al.

, 1995; Angliss and Outlaw, 2007), even without implementation of current mitigation requirements. As a result, NMFS believes that seismic survey noise in the Arctic will affect only small numbers of and have no more than a negligible impact on marine mammals in the Chukchi Sea. However, as NMFS recognizes that there is a lack of information on certain aspects of the marine mammals in the Chukchi Sea and the potential impacts on marine mammal species and stocks from offshore oil exploration, Shell (in collaboration with other offshore companies) has developed and implemented a monitoring program to address data gaps. NMFS used the best scientific information available to make the required findings under the MMPA. As explained in this document, based on that information, NMFS has determined that Shell's activities will affect only small numbers of marine mammals, will have a negligible impact on affected species or stocks, and will not have an unmitigable adverse impact on subsistence uses of the affected species or stocks.

Comment 27:

The MMC recommends that the IHA require that operations be suspended immediately if a dead or seriously injured marine mammal is found in the vicinity of the operations and if that death or injury could be attributable to the applicant's activities. Any suspension should remain in place until NMFS has: (1) reviewed the situation and determined that further deaths or serious injuries are unlikely to occur; or (2) issued regulations authorizing such takes under section 101(a)(5)(A) of the MMPA.

Response:

NMFS concurs with the MMC's recommendation and will require the immediate suspension of seismic activities if a dead or injured marine mammal has been sighted within an area where the Holder of the IHA deployed and utilized seismic airguns within the past 24 hours. Additionally, Shell is required to notify the Marine Mammal Stranding Network of stranded marine mammals.

Comment 28:

NSB and AEWC note that stranded marine mammals or their carcasses are also a sign of injury. NMFS states in its notice that it “does not expect any marine mammal will...strand as a result of the proposed survey” (74 FR 26222, June 1, 2009). In reaching this conclusion, NMFS claims that strandings have not been recorded for the Beaufort and Chukchi Seas. NSB and AEWC included a paper, which documents 25 years of stranding data, including five whales reported in 2008 alone in comparison with the five dead whales that were reported in the same area over the course of 25 years (Rosa, 2009). NSB also included some stranding reports and newspaper articles for bowhead whales discovered in the last 25 years.

In light of the increase in seismic operations in the Arctic since 2006, NSB's study raises serious concerns about the impacts of these operations and their potential to injure marine mammals. While we think this study taken together with the June 2008 stranding of “melon headed whales off Madagascar that appears to be associated with seismic surveys” (74 FR 26222, June 1, 2009) demonstrate that seismic operations have the potential to injure marine mammals beyond beaked whales (and that Shell needs to apply for an LOA for its operations), certainly NSB's study shows that direct injury of whales is on-going. These direct impacts must be analyzed and explanations sought out before additional activities with the potential to injure marine mammals are authorized.

Thus, NMFS must explain how, in light of this new information, Shell's application does not have the potential to injure marine mammals. NMFS must also require Shell to report the numbers and species of dead animals it encounters and require necropsies to be performed on dead marine mammals found during Shell's operations.

Response:

NMFS has reviewed the information provided by NSB and AEWC regarding marine mammal strandings in the Arctic. The stranding reports and accompanying newspaper articles for the three bowhead whales discovered in the 1980s and 1990s do not link the deaths to seismic activities. Rather, the two more detailed reports point to entanglement in fishing gear as the possible cause of death in both instances. Additionally, Rosa (2009) does not provide any evidence linking the cause of death for the bowhead carcasses reported in 2008 to seismic operations. Additionally, the increased reporting of carcasses in the Arctic since 2006 may also be a result of increased reporting effort and does not necessarily indicate that there were fewer strandings prior to 2008. MMOs aboard industry vessels in the Beaufort and Chukchi Seas have been required to report sightings of injured and dead marine mammals to NMFS as part of the IHA requirements only since 2006.

Regarding the June 2008 stranding of melon headed whales off Madagascar, information available to NMFS at this time indicates that the seismic airguns were not active around the time of the stranding. While the NSB study (Rosa, 2009) does present information regarding the injury of whales in the Arctic, it does not link the cause of the injury to seismic survey operations. As NMFS has stated previously, the evidence linking marine mammal strandings and seismic surveys remains tenuous at best. Two papers, Taylor

et al.

(2004) and Engel

et al.

(2004) reference seismic signals as a possible cause for a marine mammal stranding.

Taylor

et al.

(2004) noted two beaked whale stranding incidents related to seismic surveys. The statement in Taylor

et al.

(2004) was that the seismic vessel was firing its airguns at 1300 hrs on September 24, 2004, and that between 1400 and 1600 hrs, local fishermen found live stranded beaked whales 22 km (12 nm) from the ship's location. A review of the vessel's trackline indicated that the closest approach of the seismic vessel and the beaked whales stranding location was 18 nm (33 km) at 1430 hrs. At 1300 hrs, the seismic vessel was located 25 nm (46 km) from the stranding location. What is unknown is the location of the beaked whales prior to the stranding in relation to the seismic vessel, but the close timing of events indicates that the distance was not less than 18 nm (33 km). No physical evidence for a link between the seismic survey and the

stranding was obtained. In addition, Taylor

et al.

(2004) indicates that the same seismic vessel was operating 500 km (270 nm) from the site of the Galapagos Island stranding in 2000. Whether the 2004 seismic survey caused the beaked whales to strand is a matter of considerable debate (see Cox

et al.

, 2004). However, these incidents do point to the need to look for such effects during future seismic surveys. To date, follow up observations on several scientific seismic survey cruises have not indicated any beaked whale stranding incidents.

Engel

et al.

(2004), in a paper presented to the IWC in 2004 (SC/56/E28), mentioned a possible link between oil and gas seismic activities and the stranding of 8 humpback whales (7 off the Bahia or Espirito Santo States and 1 off Rio de Janeiro, Brazil). Concerns about the relationship between this stranding event and seismic activity were raised by the International Association of Geophysical Contractors (IAGC). The IAGC (2004) argues that not enough evidence is presented in Engel

et al.

(2004) to assess whether or not the relatively high proportion of adult strandings in 2002 is anomalous. The IAGC contends that the data do not establish a clear record of what might be a “natural” adult stranding rate, nor is any attempt made to characterize other natural factors that may influence strandings. As stated previously, NMFS remains concerned that the Engel

et al.

(2004) article appears to compare stranding rates made by opportunistic sightings in the past with organized aerial surveys beginning in 2001. If so, then the data are suspect.

Moreover, marine mammal strandings do not appear to be related to seismic survey work in the Arctic Ocean. Additionally, NMFS notes that in the Beaufort Sea, aerial surveys have been conducted by MMS and industry during periods of industrial activity (and by MMS during times with no activity). No marine mammal strandings have been observed during these surveys, that appear to be related to seismic survey activity, and none have been reported by NSB inhabitants (although dead marine mammals are occasionally sighted). Finally, if bowhead and gray whales react to sounds at very low levels by making minor course corrections to avoid seismic noise and mitigation measures require Shell to ramp-up the seismic array to avoid a startle effect, strandings, similar to what was observed in the Bahamas in 2000, are unlikely to occur in the Arctic Ocean. Therefore, NMFS does not expect any marine mammals will incur serious injury or mortality as a result of Shell's 2009/2010 survey operations, so an LOA is not needed.

Lastly, Shell is required to report all sightings of dead and injured marine mammals to NMFS and to notify the Marine Mammal Health and Stranding Response Network. However, Shell is not permitted to conduct necropsies on dead marine mammals. Necropsies can only be performed by people authorized to do so under the Marine Mammal Health and Stranding Response Program MMPA permit. NMFS is currently considering different methods for marking carcasses to reduce the problem of double counting. However, a protocol has not yet been developed, so marking is not required in the IHA.

Comment 29:

AWL states that additional mitigation measures are needed to address vulnerable cow/calf pairs. When assessing the potential impacts of noise, NMFS and MMS have recognized that bowhead cow/calf pairs merit special conditions. NMFS acknowledged in 2008 that more information is needed about the potential effects of even a single seismic survey on the health of females and very young calves. Collectively, these factors led NMFS to require a safety zone tailored to protect multiple migrating cow/calf pairs for the surveying that took place in both seas in 2006 and for the subsequent surveying in the Beaufort Sea in 2007 and 2008. These same factors compel a 120-dB safety zone for migrating cow/calf pairs during Shell's proposed surveying in the Chukchi Sea in 2009.

Response:

The 120-dB safety zone for migrating bowhead cow/calf pairs was implemented to reduce impacts to the animals as they migrated through the narrow corridor in the Beaufort Sea. However, in the Chukchi Sea, the migratory corridor for bowhead whales is wider and more open, thus the 120-dB ensonified zone would not impede bowhead whale migration. The animals would be able to swim around the ensonified area. Additionally, NMFS has not imposed a requirement to conduct aerial monitoring of the 120-dB safety zone for the occurrence of four or more cow-calf pairs in the Chukchi Sea because it is not practicable. First, NMFS determined that monitoring the 120-dB safety zone was not necessary in the Chukchi Sea because there would not be the level of effort by 3D seismic survey operations found in 2006. This provides cow/calf pairs with sufficient ability to move around the seismic source without significant effort. Second, aerial surveys are not required in the Chukchi Sea because they have currently been determined to be impracticable due to lack of adequate landing facilities, the prevalence of fog and other inclement weather in that area, potentially resulting in an inability to return to the airport of origin, thereby resulting in safety concerns.

Comment 30:

AEWC states the analysis that is provided regarding bowhead whales assumes, without supporting evidence, their migrations through the Chukchi follow a narrow path. AEWC and NSB note that insufficient data exist about bowhead whale and other species' use of the Chukchi, and Shell should not be authorized to operate in this sensitive area until further information has been collected. For this same reason, AEWC asks NMFS to cap the seismic and related activities that it authorizes each year in the Arctic to ensure that we are not damaging sensitive marine resources that are relied on for subsistence in ways that we are unaware of.

Response:

NMFS disagrees with the first statement. In fact, in NMFS' Notice of Proposed IHA (74 FR 26217, June 1, 2009), NMFS stated that the bowhead migration pathway is narrower and more well defined in the Beaufort Sea than in the Chukchi Sea. Regarding the comment about insufficient data, please see the response to comment 26 in this document. While NMFS acknowledges that there is some uncertainty about the status of marine mammals in and their use of the Chukchi Sea, population assessments are being conducted. NMFS used the best scientific information available to make the necessary findings required under the MMPA. Using the best available information, NMFS determined that Shell's survey will affect only small numbers of marine mammals, will have a negligible impact on affected species or stocks, and will not have an unmitigable adverse impact on the affected species or stocks for subsistence uses.

NMFS does not authorize the actual seismic and related activities. That authority falls to MMS. Rather, NMFS authorizes the take of marine mammals incidental to a specified activity (in this case, seismic activity) pursuant to sections 101(a)(5)(A) and (D) of the MMPA. While NMFS agrees that limiting the number of geophysical operations in either the Arctic would reduce impacts on marine mammals, this condition is unnecessary for a determination on whether there will be an unmitigable adverse impact on subsistence uses of marine mammals because applicants are required to complete a POC to ensure that their activities will not affect subsistence hunts. As described elsewhere in this document, Shell has incorporated design features into their program,

signed the 2009 CAA, and implemented a POC, and NMFS has included measures in the IHA to ensure no unmitigable adverse impacts to subsistence hunts.

NMFS understands that, under the terms of an OCS lease, the lessee is required to make progress on exploration and development on its leases in order to hold that lease beyond the initial lease term. Ancillary activities (such as seismic and shallow hazard surveys) are those activities conducted on a lease site to obtain data and information to meet MMS' regulations to explore and develop a lease. If a limit is placed by NMFS on the number of ancillary activities authorized for a planning area in a given year, NMFS may preclude the lessee from complying with MMS regulations to proceed in a timely manner on exploring or developing its OCS leases. Therefore, based on both practicability and that it is not necessary, NMFS has not adopted this suggested mitigation measure. However, NMFS encourages industry participants to work together to reduce seismic sounds in the Arctic Ocean through cooperative programs in data collection to reduce impacts on marine mammals.

Comment 31:

NSB states that Shell needs to consider impacts on those species that may not occur in the project area in “meaningful numbers.”

Response:

Although bowhead, beluga, and gray whales and harbor porpoise are more likely to occur in the project area than other cetacean species (i.e., humpback, fin, killer, and minke whale), all of these species were described and analyzed in Shell's application and NMFS' proposed IHA (74 FR 26217, June 1, 2009).

Comment 32:

NSB notes that Shell states, “These types of surveys, collectively and individually, have not resulted in impacts of biological significance to marine mammals of the Arctic...” Shell does not have data to support this statement, as Shell and other oil and gas companies have yet to examine whether there have been impacts of biological significance from exploration activities in the Beaufort and Chukchi Seas. Determination of the biological significance of impacts from oil and gas activities (beyond just behavioral deflection) is needed. Further, “biological significance” must be defined. NSB also notes that Shell states, “Any effects would be temporary and of short duration at any one place.” It is difficult, if not impossible to judge this statement from the information included in this IHA.

Response:

To date, there have not been any reported large scale impacts attributable to offshore oil and gas development in the Arctic. NMFS would expect that villagers who hunt and fish in the offshore waters would notice changes in marine life. However, NMFS agrees that there is some uncertainty on the current status of some marine mammal species in the Beaufort and Chukchi Seas and on impacts on marine mammals from seismic surveys. NMFS is currently proposing to conduct new population assessments for Arctic pinniped species and current information is available on-line through its SARs program. As stated previously, NMFS determines whether takings by harassment are occurring based on whether there is a significant behavioral change in biologically important activity, such as feeding, breeding, migration or sheltering. All of these activities are potentially important for reproductive success of a marine mammal population (67 FR 46722, July 16, 2002). In regard to impacts, there is no indication that seismic survey activities are having a long-term impact on marine mammals. For example, apparently, bowhead whales continued to increase in abundance during periods of intense seismic in the Chukchi Sea in the 1980s (Raftery

et al.

, 1995; Angliss and Outlaw, 2007), even without implementation of current mitigation requirements. As a result, NMFS has determined that seismic survey noise in the Arctic will have no more than a short-term effect on marine mammals in the Chukchi Sea.

Large-scale impact assessments on marine mammal species from offshore seismic activities have been ongoing since 2006 through the industry's comprehensive monitoring plan. NMFS along with AEWC, NSB, oil exploration companies, and others have developed an off-seismic vessel monitoring program to help address the potential impact of seismic activities on marine mammals and subsistence uses of marine mammals. This program is described later in this document (see “Comprehensive Monitoring Reports”). If NSB wishes to set alternative priorities for this impact assessment program, it should make that concern known to NMFS and Shell as soon as possible.

Comment 33:

NSB notes that Shell states, “Excessive amounts of repeated exposure can lead to overestimation of the number of animals potentially exposed through double counting.” NSB indicates that this can also cause greater harm in animals exposed multiple times/chronically.

Response:

Repeated exposure may cause a marine mammal to exhibit diminished responsiveness (habituation), or disturbance effects may persist; the latter is most likely with sounds that are highly variable in characteristics, infrequent, and unpredictable in occurrence, and associated with situations that a marine mammal perceives as a threat. Additionally, the relatively short cross-track distance of the 160-dB radius associated with Shell's site clearance and shallow hazards surveys result in little overlap of exposed waters during the survey.

Moreover, as explained in detail elsewhere in this document, marine mammals will need to be significantly closer to the seismic source and be exposed to SPLs greater than 180 dB to be injured or killed by the airgun array. For large airgun arrays (much larger than the array to be used by Shell in 2009/2010), this distance may be within 200 m (656 ft) of the vessel. In order for a marine mammal to receive multiple exposures (and thereby incur PTS), the animal would: (1) need to be close to the vessel and not detected during the period of multiple exposure; (2) be swimming in approximately the same direction and speed as the vessel; and (3) not be deflected away from the vessel as a result of the noise from the seismic array. Preliminary model simulations for seismic surveys in the Gulf of Mexico indicate that marine mammals are unlikely to incur single or multiple exposure levels that could result in PTS, as the seismic vessel would be moving at about 4-5 knots, while the marine mammals would not likely be moving within the zone of potential auditory injury in the same direction and speed as the vessel, especially for those marine mammals that take measures to avoid areas of seismic noise.

Comment 35:

Citing research on long term adverse effects to whales and dolphins from whale watching activities (Trites and Bain, 2000; Bain, 2002; Lusseau

et al.

, 2006), Dr. Bain states that Level B behavioral harassment could be the primary threat to cetacean populations.

Response:

Although NMFS agrees that long-term, persistent, and chronic exposure to Level B harassment could have a profound and significant impact on marine mammal populations, such as described in the references cited by Dr. Bain, those examples do not reflect the impacts of seismic surveys to marine mammals for Shell's project. First, whale watching vessels are intentionally targeting and making close approaches to cetacean species so the tourists onboard can have a better view of the animals. Some of these whale/dolphin

watching examples cited by Dr. Bain occurred in the coastal waters of the Northwest Pacific between April and October and for extended periods of time (“[r]ecreational and scientific whale watchers were active by around 6 a.m., and some commercial whale watching continued until around sunset”). Thus multiple vessels have been documented to be in relatively close proximity to whales for about 12 hours a day, six months a year, not counting some “out of season” whale watching activities and after dark commercial filming efforts. In addition, noise exposures to whales and dolphins from whale watching vessels are probably significant due to the vessels' proximity to the animals. To the contrary, Shell's proposed open-water shallow hazard and site clearance surveys, along with existing industrial operations in the Arctic Ocean, do not intentionally approach marine mammals in the project areas. Shell's survey locations are situated in a much larger Arctic Ocean Basin, which is far away from most human impacts. Therefore, the effects from each activity are remote and spread farther apart, as analyzed in NMFS' 2009 EA, as well as the MMS 2006 PEA.

Shell's site clearance and shallow hazards activities would only be conducted between August and October for 50 days, weather permitting. In addition, although studies and monitoring reports from previous seismic surveys have detected Level B harassment of marine mammals, such as avoidance of certain areas by bowhead and beluga whales during the airgun firing, no evidence suggests that such behavioral modification is biologically significant or non-negligible (Malme

et al.

, 1986, 1988; Richardson

et al.

, 1987, 1999; Miller

et al.

, 1999, 2005), as compared to those exposed by chronic whale watching vessels cited by Dr. Bain. Therefore, NMFS believes that potential impacts to marine mammals in the Chukchi Sea by site clearance and shallow hazards surveys would be limited to Level B harassment only, and due to the limited scale and remoteness of the project in relation to a large area, such adverse effects would not accumulate to the point where biologically significant effects would be realized.

Comment 36:

Dr. Bain states that changes in behavior resulting from noise exposure could lead to indirect injury in marine mammals in the wild. He presented several examples to suggest that marine mammals repeatedly exposed to Level B harassment could result in Level A takes: (1) Harbor porpoise were observed traveling at high speeds during exposure to mid-frequency sonar in Haro Strait in 2003 and that exhaustion from rapid flight could lead to mortality; (2) citing MMS' (2004)

Environmental Assessment on Proposed Oil and Gas Lease Sale 195 in the Beaufort Sea Planning Area

(OCS EIS/EA MMS 2004-028) that feeding requires a prey density of 800 mg/m3 and his own observation, Dr. Bain is concerned displacement from high productive feeding areas would negatively affect individual whales and that small cetaceans such as harbor porpoise would face a risk of death if they are unable to feed for periods as short as 48 - 72 hours, or they may move into habitat where they face an increased risk of predation; (3) individual killer whales have been observed splitting from their pod when frightened by sonar and that other killer whales' separation from their social units has resulted in death; (4) TTS may lead to harm, as a minke whale was nearly struck by a research vessel in the area where one had been observed fleeing mid-frequency sonar, and blunt force trauma was identified as a cause of death in the investigation of harbor porpoise mortalities following exposure to mid-frequency sonar; and (5) impaired auditory ability may increase predation, as white-sided dolphins were attacked by killer whales because the noise of the research vessel caused the approach of the killer whales to go undetected by the dolphins.

Response:

NMFS agrees that it is possible that changes in behavior or auditory masking resulting from noise exposure could lead to injury in marine mammals under certain circumstances in the world, such as those examples/hypotheses raised by Dr. Bain. However, it is not likely that received SPLs from the site clearance and shallow hazards surveys would drastically cause changes in behavior or auditory masking in marine mammals in the vicinity of the action area. First, marine mammals in the aforementioned examples and hypotheses were exposed to high levels of non-pulse intermittent sounds, such as military sonar, which has been shown to cause flight activities (e.g., Haro Strait killer whales); and continuous sounds such as the vessel, which could cause auditory masking when animals are closer to the source. The sources produced by the acoustic equipment and airguns for Shell's site clearance and shallow hazards surveys are impulse sounds used in seismic profiling, bathymetry, and seafloor imaging. Unlike military sonar, seismic pulses have an extremely short duration (tens to hundreds of milliseconds) and relatively long intervals (several seconds) between pulses. Therefore, the sound energy levels from these acoustic sources and small airguns are far lower in a given time period. Second, the intervals between each short pulse would allow the animals to detect any biologically significant signals, and thus avoid or prevent auditory masking. In addition, NMFS requires mitigation measures to ramp-up acoustic sources at a rate of no more than 6 dB per 5 min. This ramp-up would prevent marine mammals from being exposed to high level noises without warning, thereby eliminating the possibility that animals would dramatically alter their behavior (i.e. from a “startle” reaction). NMFS also believes that long-term displacement of marine mammals from a feeding area is not likely because the seismic vessel is constantly moving, and the maximum 160-dB ensonified radius is about 1.4 km, which would create an area of ensonification of approximately 6 km

2

at any given moment, which constitutes a very small portion of the Chukchi Sea (0.001 percent). In reality, NMFS expects the 160-dB ensonified zone to be smaller due to absorption and attenuation of acoustic energy in the water column.

Comment 36:

AEWC states that NMFS does little to assess whether Level A harassment is occurring as a result of the deflection of marine mammals as a result of Shell's proposed operations. Deflected marine mammals may suffer impacts due to masking of natural sounds including calling to others of their species, physiological damage from stress and other non-auditory effects, harm from pollution of their environment, tolerance, and hearing impacts (see Nieukirk

et al.

, 2004). Not only do these operations disrupt the animals' behavioral patterns, but they also create the potential for injury by causing marine mammals to miss feeding opportunities, expend more energy, and stray from migratory routes when they are deflected. Dr. Bain also states that there are three main ways that minor behavioral changes, when experienced by numerous individuals for extended periods of time, can affect population growth: increased energy expenditure, reduced food acquisition, and stress (Trites and Bain, 2000).

Response:

See the response to comment 35 regarding the potential for injury. The paper cited by AEWC (Nieukirk

et al.

, 2004) tried to draw linkages between recordings of fin, humpback, and minke whales and airgun signals in the western North Atlantic; however, the authors note the difficulty in assessing impacts based on the data collected. The authors also state

that the effects of airgun activity on baleen whales is unknown and then cite to Richardson

et al.

(1995) for some possible effects, which AEWC lists in their comment. There is no statement in the cited study, however, about the linkage between deflection and these impacts. While deflection may cause animals to expend extra energy, there is no evidence that this deflection is causing a significant behavioral change to a biologically significant activity. In fact, bowhead whales continued to increase in abundance during periods of intense seismic in the Chukchi Sea in the 1980s (Raftery

et al.

, 1995; Angliss and Outlaw, 2007). Therefore, NMFS does not believe that injury will occur as a result of Shell's activities. Additionally, Shell's total data acquisition activities will occur in an extremely small portion of the Chukchi Sea (0.2 percent). Therefore, based on the smaller radii associated with Shell's site clearance and shallow hazards surveys than the larger 2D or 3D seismic programs and the extremely small area of the Chukchi Sea where Shell will utilize airguns, it is unlikely that marine mammals will need to expend extra energy to locate prey or to have reduced foraging opportunities.

Comment 37:

Citing Erbe (2002), AEWC notes that any sound at some level can cause physiological damage to the ear and other organs and tissues. Placed in a context of an unknown baseline of sound levels in the Chukchi Sea, it is critically important that NMFS take a precautionary approach to permitting additional noise sources in this poorly studied and understood habitat. Thus, the best available science dictates that NMFS use a more cautious approach in addressing impacts to marine mammals from seismic operations.

Response:

The statement from Erbe (2002) does not take into account mitigation measures required in the IHA to reduce impacts to marine mammals. As stated throughout this document, based on the fact that Shell will be using a small airgun array (total discharge volume of 40 in

3

) and will implement mitigation measures (i.e., ramp-up, power-down, shutdown, etc.), NMFS does not believe that there will be any injury or mortality of marine mammals as a result of Shell's operations.

Comment 38:

AEWC states that in making its negligible impact determination, NMFS failed to consider several impacts: (1) Non-auditory, physiological effects, namely stress; (2) the possibility of vessel strikes needs to be considered in light of scientific evidence of harm from ship traffic to marine mammals; (3) impacts to marine mammal habitat, including pollution of the marine environment and the risk of oil spills, toxic, and nontoxic waste being discharged; (4) impacts to fish and other food sources upon which marine mammals rely; (5) specific marine mammals that will be taken, including their age, sex, and reproductive condition; and (6) the use of multiple airguns at one time. For this last point, referencing Nieukirk

et al.

(2004) and NRC (2003), AEWC states that the impacts from airguns cannot simply be discounted by assuming that most of the energy is focused vertically, and, thus, the impacts horizontally are not great. Dr. Bain also notes that directional sources and arrays produce significant energy in directions other than their primary direction.

Response:

NMFS does not agree that these impacts were not considered. First, non-auditory, physiological effects, including stress, were analyzed in the Notice of Proposed IHA (74 FR 26217, June 1, 2009). No single marine mammal is expected to be exposed to high levels of sound for extended periods based on the size of the airgun array to be used by Shell and the fact that an animal would need to swim close to, parallel to, and at the same speed as the vessel to incur several high intensity pulses. This also does not take into account the mitigation measures described later in this document.

Second, impacts resulting from vessel strikes and habitat pollution and impacts to fish were fully analyzed in MMS' 2006 Final PEA and incorporated by reference into NMFS' 2009 EA for Shell's activities. Additionally, the proposed IHA analyzed potential impacts to marine mammal habitat, including prey resources. That analysis noted that while mortality has been observed for certain fish species found in extremely close proximity to the airguns, Saetre and Ona (1996) concluded that mortality rates caused by exposure to sounds are so low compared to natural mortality that issues relating to stock recruitment should be regarded as insignificant. Based on the small portion of the Chukchi Sea that will be ensonified during Shell's activities, less than 0.1 percent of available food resources are anticipated to be impacted, which would have little, if any, effect on a marine mammal's ability to forage successfully.

For the fifth point, please see the response to comment 11. The age, sex, and reproductive condition must provided when possible. However, this is often extremely difficult to predict. Additional mitigation measures for bowhead cow/calf pairs, such as monitoring the 120-dB radius and requiring shutdown when 4 or more cow/calf pairs enter that zone, were considered but determined to be impracticable for this survey. As stated elsewhere in this document, due to safety concerns, aerial surveys are not required in the offshore Chukchi Sea environment. Regarding the last point raised by AEWC, NMFS analyzed impacts from the use of an airgun array with a total discharge volume of 40 in

3

. In its analysis, NMFS did not discount the impacts from airguns by simply assuming that most of the energy is focused downward (i.e., vertically). While the fact that the downward direction of the airguns minimizes sound that is emitted in the horizontal direction, NMFS fully analyzed the impacts of airgun sounds on marine mammals and has required monitoring and mitigation measures to reduce the impacts further. Based on the information contained in this response and the analyses in the proposed IHA and NMFS' EA, NMFS determined that impacts to marine mammals as a result of Shell's action will be negligible.

Comment 39:

NSB notes that Shell's application states, “In the absence of important feeding areas, the potential diversion of a small number of bowheads is not expected to have any significant or long-term consequences for individual bowheads or their population. Bowheads, gray, or beluga whales are not predicted to be excluded from any habitat.” If these whales are avoiding the 160 dB and potentially the 120 dB isopleths, and the logic that is used for use of the mitigation gun is that the sound “clears” the area, then, yes, they will most certainly be excluded from part of their habitat.

Response:

NMFS agrees with NSB's statement that whales will likely be excluded from part of their habitat. However, the exclusion is expected to be temporary and would not affect feeding opportunities because only an extremely small fraction of the Chukchi Sea will be ensonified as a result of Shell's operations (less than 0.2 percent). Implicit in this conclusion, therefore, is that there will be many other areas available to whales for feeding and other biologically important activities.

Acoustic Impacts

Comment 40:

Citing studies on noise impacts to chinchillas (Henderson

et al.

, 1991) and human noise exposure standards by the U.S. Occupational Safety Health Administration (OSHA), Dr. Bain states, “[I]n humans, chronic exposure to levels of noise too low to generate a TTS can result in PTS.” As OSHA standards require limiting human

exposure to noise at 115 dBA above threshold to 15 minutes per day, Dr. Bain concludes that this level is equivalent to 145 dB re 1 μPa for killer whales. Dr. Bain states that although the reference levels for sound in air and water are different, this difference is taken into account when determining thresholds.

Dr. Bain notes that while OSHA's standards are for continuous noise and assume multi-year exposure, surveys employ multiple intermittent sources, which in a reverberant environment, have the potential to become nearly continuous. While individual projects will cause limited exposure to individual marine mammals, these individuals will accumulate exposure from natural sources (e.g., wind) and human activities (e.g., other seismic surveys, vessel traffic) conducted over the course of their lifetime.

Response:

Although NMFS agrees that chronic exposure to noise levels that would not cause TTS could result in hearing impairment in the long-term, it is important to understand that such exposure has to be of a chronic and long-term nature. The OSHA standards for permissible exposure are based on daily impacts throughout an employee's career, while the noise exposure to seismic surveys by marine mammals is short-term and intermittent (surveys occur for 2-3 months in a given year), as described in the Notice of Proposed IHA and NMFS' EA. In addition, the reference Dr. Bain cites (Henderson

et al.

, 1991) does not address chronic noise impact to humans. The research by Henderson

et al.

(1991) focused on the applicability of the equal energy hypothesis (EEH) to impact (impulse) noise exposures on chinchillas, and the results indicated that hearing loss resulting from exposure to impact noise did not conform to the predictions of the EEH, which is the basis for OSHA standards for continuous noise exposure.

Most importantly, Dr. Bain's extrapolation of 145 dB re 1 Pa for killer whale hearing safety from OSHA's 115 dBA is fundamentally flawed for three reasons:

(1) The reference points when using decibel units that address sound in air and in water are different. For airborne sounds, such as those by OSHA, the reference point is 20 μPa, while for underwater sounds, the reference point is 1 μPa. There is a 26 dB difference between the values when different reference points are used for the same sound pressure; therefore, 115 dB re 20 μPa is 141 dB re 1 μPa for the same sound pressure. So 115 dB re 20 μPa in air above human threshold (defined as 0 dB re 20 μPa in air) would be 141 dB re 1 μPa underwater for the same sound pressure. Using the lowest threshold of 30 dB re 1 μPa as the killer whale hearing threshold and assuming that noise impacts to killer whales are the same as for humans, one could extrapolate that continuous noise exposure of 171 dB re 1 μPa (141 dB over the 30 dB threshold) for 15 minutes for killer whales would be equivalent to humans exposed to 115 dB re 20 Pa for 15 minutes. Nevertheless, such extrapolation still leaves much uncertainty since marine mammals have a different mechanism for sound reception (Au, 1993; Richardson

et al.

, 1995). Some of the most recent science has shown that for some odontocetes, the onset of TTS when exposed to impulse noise is much higher (Finneran

et al.

, 2002) than NMFS' current thresholds.

(2) The decibel values used by OSHA are expressed as broadband A-weighted sound levels expressed in dBA. This frequency-dependent weighting function is used to apply to the sound in accordance with the sensitivity of the human ear to different frequencies. Thus, it is inappropriate to compare these values to an animal's hearing capability, including how an animal perceives sound in air (Richardson

et al.

, 1995). For marine mammals, M-weighting functions have been suggested based on five different hearing functional groups to address different hearing sensitivities of different frequencies by each of the marine mammal groups (Southall

et al.

, 2007).

(3) Finally, the sound characteristic used in OSHA standards is continuous sound, while the seismic sound from the proposed shallow hazard and site clearance surveys is impulse sound, which by its very nature is not a continuous sound. There are several seconds between each shot, and each shot only lasts for a few milliseconds. Therefore, the amount of time without seismic sound between each shot is greater than 99 percent. As there is a significant period of time between shot events, this does not qualify as a continuous sound source. NMFS' EA assessed the cumulative impacts from all activities in the Chukchi Sea. Based on that assessment, NMFS determined that Shell's activities would not produce any significant cumulative impacts to the human environment (i.e., marine mammals).

Comment 41:

Dr. Bain states that sound sources are typically divided into continuous and pulsed categories, and that behavioral effects from pulsed sound are likely to be independent of the repetition rate and duty cycle and depend primarily on the duration of the survey. Dr. Bain further states that intermittent pulses can result in continuously received noise when sound arrives via multiple paths, which Dr. Bain explains as “sound that bounces between the bottom and the surface will take longer to reach an animal than sound traveling via a direct path,” and that “noise can mask signals for a brief period before and after it is received, meaning an almost continuous received noise can mask signals continuously.”

Response:

NMFS does not agree with Dr. Bain's statement on ocean acoustics and his subsequent analysis and assessment regarding underwater sound propagation and its effects to marine mammals. Within the scientific community on ocean acoustics and bioacoustics, two types of sound are traditionally recognized: transient sounds (sounds of relatively short duration) and continuous sounds (sounds that go on and on). Transient sounds can be further classified into impulsive (such as seismic airguns, explosives, pile driving) and non-impulsive (such as military tactic sonars) sounds (Richardson

et al.

, 1995). Other researchers studying noise impacts on marine mammals classified sound types into a single pulse (a single explosive), multiple pulses (seismic airguns, pile driving), and non-pulses (ships, sonar) (Southall

et al.

, 2007). A simple way to distinguish pulses sound from non-pulses (continuous sound included) is that the former have rapid rise-time in relation to its extremely short duration. As mentioned in the response to comment 25, behavioral responses from marine mammals when exposed to underwater noise is complex and context specific, and often depend on the sound characteristics (such as received levels, duration, duty cycles, frequency, etc.) and other variables.

NMFS agrees that the distinction between transient and continuous sounds is not absolute, as continuous sound from a fast moving vessel is often treated as transient sound in relation to a stationary or slow moving marine mammal. Further, the distinction between pulses and non-pulses is also not always clear, as certain pulsed sound sources (e.g., seismic airguns and explosives) may become non-pulses at greater distances due to signal decay through reverberation and other propagation paths. However, Dr. Bain's statement that intermittent pulses can result in continuously received noise when sound arrives via multiple paths is unfounded. For a marine mammal exposed to noise, multipath propagation

would expose the animal to the noise multiple times, usually each subsequent exposure with lower sound level due to loss of acoustic energy from surface and bottom reflections; however, the noise arriving via multipath propagation would not become continuous sound because the intervals between signals would always exist. In addition, noise cannot mask a signal before or after it is received by the animal. Masking of signals can only occur when the unwanted sound (noise) interferes with the signal when received by the animal, generally at similar frequencies (Richardson

et al.

, 1995). Therefore, Dr. Bain's assessment regarding the potential impact of the acoustic sources to be used during Shell's operations is not supported.

Comment 42:

Dr. Bain states that one characteristic of pulsed sources is known as “time-bandwidth” product, and he explains that it is “any sound with a finite duration (that is, any real-world sound) contains additional frequencies to the nominal frequency. That is, pulsed sources that nominally have a frequency that is too high to hear, may, in fact, be audible, as the source will contain lower frequencies that are detectable.”

Response:

NMFS does not agree with Dr. Bain's statement that high frequency pulsed sources nominally contain additional frequencies that are audible. The high frequency pulsed sources are expected to operate within their frequency range, although some mechanical noise at lower frequencies may be produced as a byproduct during the operation. The mechanical noise associated with acoustic equipment is expected to be low intensity and is not expected to result in harassment of marine mammals. Furthermore, the term “time-bandwidth product” is generally used in signal process, which is irrelevant to the Chukchi Sea site clearance and shallow hazards survey.

Marine Mammal Biology Concerns

Comment 43:

NSB states that Table 4-1 in Shell's application should be organized based on the NMFS accepted stocks of marine mammals, which is the appropriate management unit. For example, beluga whales should be evaluated for the Beaufort Sea stock and the eastern Chukchi Sea stock. Population estimates (including nmin, point estimate for stock size, and confidence interval around that point estimate) should be given for each stock. Grouping by species is misleading and inappropriate.

Furthermore, Shell separates out numbers of marine mammals by offshore vs. nearshore/ice edge. This approach is confusing, inappropriate for the Chukchi Sea, and needs to be refined. Marine mammals occur and migrate across the entire area. Designating a separate abundance for offshore and nearshore is not appropriate and is not helpful for evaluating the potential for small takes of marine mammals.

The pinniped section of Table 4-1 is also misleading. All four species occur in areas other than sea ice. Shell's estimate of the number of spotted seals is incorrect. The provided estimate is from a MMS document and is only for the Beaufort Sea. Thousands of spotted seals use Chukchi Sea haulouts. That information should be provided in the application.

Response:

Table 4-1 is meant to provide an overview of the marine mammals that are described in detail in Section 4 of Shell's application. The different stocks that may be encountered during Shell's activities are described in the text portions of the application that follow the table. For example, the discussion for beluga whales describes both the Beaufort Sea stock and the eastern Chukchi Sea stock. Where available, the requested information (e.g., nmin, point estimate for stock size, etc.) was provided; however, that information is not available in the NMFS SARs for all Arctic species. Shell will consider revising this table in future IHA applications. The textual descriptions also provide additional information on the use of the Chukchi Sea by the different species listed in Table 4-1 and a Chukchi Sea specific abundance estimate for spotted seals.

Comment 44:

NSB states that the last paragraph in the beluga section of the application (page 16) is incomplete. Decision makers and the public need to be aware that the entire Beaufort and Chukchi populations of belugas migrate through the Chukchi Sea during the autumn. This information is necessary because Shell's proposed work is in the Chukchi Sea and may impact beluga whales. Therefore, appropriate monitoring and mitigation plans are needed for the central Chukchi Sea.

Response:

Discussion of the migration patterns of the Beaufort Sea stock of beluga whales is contained earlier in the beluga whale description (page 15 of the application). NMFS considered impacts to beluga whales during Shell's Chukchi operations. The IHA issued to Shell contains appropriate monitoring and mitigation measures (described in detail later in this document) for all marine mammal species under NMFS' jurisdiction.

Comment 45:

NSB notes that statements regarding bowheads summering in the Chukchi Sea and feeding in the Beaufort Sea are incomplete. They provide statements of sightings during the summer months, indicating that not all bowheads migrate to the eastern Beaufort Sea in the summer. This information is needed by decision makers and the public to better assess the potential impacts from oil and gas activities on bowheads.

Response:

MMS' 2006 Final PEA contains a discussion about bowhead migration and references scientific literature and accounts from hunters, indicating that some bowheads may summer in the western Beaufort Sea or Chukchi Sea. This information was incorporated by reference into NMFS' 2009 EA for the issuance of an IHA to Shell and was considered in making the necessary MMPA findings.

Comment 46:

NSB states that the discussion of results from Shell's aerial surveys regarding gray whales is misleading. Shell states that gray whales were most abundant near shore between Barrow and Wainwright; however, Shell did not conduct aerial surveys in offshore areas, including in the proposed operation area. Shell's visual observations in offshore areas came solely from observers on boats. It is not reasonable to compare aerial and vessel surveys to conclude that gray whales are mostly using nearshore areas. Scientific information on how gray whales are using offshore areas should be considered limited at this time.

Response:

Comment noted. In assessing impacts to gray whales, NMFS considered that individuals may occur within the action area. Estimated take numbers for gray whales reflect the fact that the animals may use offshore areas near Shell's operations (see the “Estimated Take of Marine Mammals” section later in this document).

Comment 47:

AWL states that there is insufficient information in the proposed IHA

Federal Register

notice related to gray whales to justify NMFS' MMPA conclusions. Gray whales have been shown to abandon habitat in response to anthropogenic noise. It is not clear that NMFS considered the proximity of Shell's proposed survey areas to the Hanna Shoal or other potential eastern gray whale feeding areas.

AWL and Dr. Bain note that gray whale numbers have declined since de-listing of the species in 1994. Dr. Bain states that this raises the question of whether gray whales should be re-listed as threatened under the ESA since their population has a negative trend and is at a level that was considered threatened even when it was increasing. One implication of re-listing would be a change in the recovery factor for

calculating Potential Biological Removal (PBR). Using the value for an ESA-listed species would reduce PBR to 42. Subsistence harvest in Russia alone exceeds this number. Thus, additional threats such as habitat loss due to disturbance from seismic surveys would result in further jeopardy to the survival of the species. It is clear that a careful evaluation of this species is needed before activities that disturb gray whales are allowed.

Response:

NMFS considered the potential impacts of the site clearance and shallow hazards surveys on gray whales. MMS' 2006 Final PEA contains discussion and analysis of the potential effects of airgun noise on gray whales, including avoidance of habitat when seismic surveys are occurring. This information was considered by NMFS and incorporated by reference into the EA prepared for this action. Through this analysis, NMFS considered the fact that the Chukchi Sea is considered a primary summer feeding ground for the eastern North Pacific stock of gray whales. However, NMFS determined that Shell's surveys will impact only small numbers of gray whales and will have a negligible impact on the affected stock. This determination was made based on several factors: (1) the small size of the airgun array (40 in

3

); (2) the short duration of the survey (approximately 50 days); and (3) the incorporation of the required mitigation and monitoring measures described later in this document.

Since 1994, NMFS has continued to monitor the status of the population consistent with its responsibilities under the ESA and the MMPA. In 1999, a NMFS review of the status of the eastern North Pacific stock of gray whales recommended the continuation of this stock's classification as non-threatened (Rugh

et al.

, 1999). Workshop participants determined the stock was not in danger of extinction, nor was it likely to become so in the foreseeable future. In 2001 several organizations and individuals petitioned NMFS to re-list the eastern North Pacific gray whale population. NMFS concluded that there were several factors that may be affecting the gray whale population but there was no information indicating that the population may be in danger of extinction or likely to become so in the foreseeable future. Wade and Perryman (2002) and Punt

et al.

(2004) (cited in the 2008 SAR, Angliss and Allen, 2009) found that the stock is within its optimum sustainable population level and that the population is likely close to or above its unexploited equilibrium level. NMFS continues to monitor the abundance of the stock through the MMPA stock assessment process, especially as it approaches its carrying capacity. If new information suggests a reevaluation of the eastern North Pacific gray whales' listing status is warranted, NMFS will complete the appropriate reviews. Lastly, Shell's surveys are not expected to destroy or result in any permanent impact on habitats used by gray whales or to their prey resources or to jeopardize the continued existence of the species.

Comment 48:

AWL, Dr. Bain, and AEWC state that the division of the harbor porpoise population in Alaska is incorrect. Dr. Bain and AEWC cite to the 2008 harbor porpoise Bering Sea stock SAR (Angliss and Allen, 2009):

In cases outside of Alaska, studies have shown that stock structure is more fine-scale than is reflected in the Alaska Stock Assessment Reports. At this time, no data are available to reflect stock structure for harbor porpoise in Alaska. However, based on comparisons with other regions, smaller stocks are likely. Should new information on harbor porpoise become available, the harbor porpoise Stock Assessment Reports will be updated.

That is, the stock to be affected by the survey is likely to be far smaller than currently recognized. The implication is that the population is far less able to tolerate takes than expected based on the current stock definition. AWL states that while NMFS is not required to develop a definitive stock assessment, it cannot rely on concededly inaccurate information in order to comply with its MMPA obligations. AEWC states that without knowing whether a specific stock of harbor porpoise exists in the area that will be impacted by Shell's operations and the population numbers and health of that stock, NMFS cannot determine the level of take and whether such take will be negligible to the stock. Thus, operations in the Chukchi should not proceed until additional studies have been conducted.

Response:

Currently, there are insufficient samples to draw conclusions about stock structure of harbor porpoise within Alaska. While NMFS acknowledges that perhaps smaller stocks should be recognized in Alaska, the best science currently available indicates that Shell's activities will potentially impact only small numbers of harbor porpoise and will not have a negligible impact on the affected species or stock. Using the current estimated stock size for the Bering Sea stock, only 0.01 percent is estimated to be taken by harassment. If the number should be something closer to the low 1,000s (as suggested by AWL), this would still represent less than 1 percent of the stock size. NMFS does not agree that just because a stock contains fewer individuals than originally estimated that it is far less able to tolerate takes than expected. Dr. Bain does not provide any scientific evidence for this statement.

Comment 49:

Dr. Bain states that another point of concern regarding the harbor porpoise is that NMFS is reviewing new data on other sources of takes but will not complete the analysis until next year (Allen and Angliss, in prep.). These data are needed to assess the cumulative effects of the proposed survey and other factors that impact the population.

Response:

While the draft 2009 SAR (Allen and Angliss, in prep.) states that more current data on fishery-related serious injury and mortality are being analyzed and will be available for inclusion in the 2010 SAR, it also states that in 2001 only one fishery-related harbor porpoise mortality was recorded in 2001, and none were recorded for the period 2002-2006. Although no records are currently available for 2007-2009, the estimated level of human-caused mortality and serious injury is not known to exceed PBR (Allen and Angliss, in prep.). NMFS assessed cumulative impacts to all marine mammals that may occur in the area of Shell's operations in its 2009 EA. Based on that assessment, NMFS concluded that issuance of an IHA to Shell to conduct its open-water marine survey program in the Chukchi Sea during the 2009/2010 Arctic open-water season would not produce any significant cumulative impacts to the human environment.

Comment 50:

NSB notes that more information is needed regarding use of the Chukchi Sea and how environmental changes may affect that use for bearded and ringed seals.

Response:

As required by the MMPA implementing regulations at 50 CFR 216.102(a), NMFS has used the best scientific information available in making its determinations required under the MMPA. While recent stock assessments are lacking for several species of ice seals, for reasons stated elsewhere in this

Federal Register

Notice, no ice seals are expected to be killed or seriously injured as a result of Shell's site clearance and shallow hazards surveys and the number of takings by Level B harassment will be small relative to the best estimate of population size. Therefore, NMFS has determined that Shell's activity would not result in a decrease in population sizes of any of the ice seal species. As a result of our analysis, NMFS believes that Shell's proposed site clearance and

shallow hazard surveys are not expected to have adverse impacts on ice seals.

Density and Take Estimate Concerns

Several of the comment letters addressed concerns over the species densities used by Shell to calculate take estimates. In general, the commenters believed that Shell used flawed density estimates, which then led to incorrect take estimates. This subsection addresses those concerns and provides further explanation beyond the information and explanations provided in Shell's application and the Notice of Proposed IHA (74 FR 26217, June 1, 2009). Dr. Sue Moore was one of the independent peer reviewers for Shell's 4MP. Those comments are addressed in the “Monitoring Plan Independent Peer Review” subsection later in this document. However, Dr. Moore also provided comments on the density estimates used by Shell, which are more appropriately addressed in this subsection.

Comment 51:

NSB states, “Shell contends that “Animal [marine mammal] densities are generally expected to be lower in deep water, and at locations far-offshore'” (page 13 in Shell's application). Shell does not provide references to support this statement. It is possible that the statement is based on visual surveys in offshore areas conducted from boats during the past 3 years. (Shell's nearshore surveys were conducted by plane.) Because of the impact from boat sounds, including 3D seismic, to marine mammals and the limited efficacy of MMOs, it is inappropriate to compare density estimates from the nearshore and offshore areas using these two different methods. Moreover, Shell's 2008 report on the “Joint Monitoring Program” showed that in some cases the number of marine mammal calls detected was greater in offshore areas compared to nearshore areas.

Response:

The statement is a generalization across multiple species and seasons and does not indicate that it applies for all species (use of the word “generally”). Additionally, this statement was written when the application was also considering estimates of marine mammals in the Beaufort Sea. For example, results presented in Moore

et al.

(2000b) for bowhead and beluga whales during the summer months in the Beaufort Sea and to some extent for gray whales in the Chukchi Sea support this statement, as well as statements contained in Bengtson

et al.

(2005) for ringed and bearded seals. However, it is possible that certain species may be encountered in higher densities in offshore areas. The paragraph from which this statement was taken was merely an introduction. Species specific descriptions are contained in the following pages of the application.

Comment 52:

AEWC states that in assessing the level of take and whether it is negligible, NMFS relied on flawed density estimates that call into question all of NMFS' preliminary conclusions. Density data are lacking or outdated for almost all marine mammals that may be affected by Shell's operations in the Chukchi Sea, especially for the fall. A few species specific examples are provided that illustrate NMFS' failure to utilize the best available scientific studies in assessing Shell's application.

NMFS' guess at the number of beluga and bowhead whales in the Chukchi in the summer relies on a study from Moore

et al.

that was published in 2000 based upon information from “industry vessels.” The estimate is contrary to the best available scientific information on beluga whale presence in the Chukchi in the SAR from 2005. While more updated information is necessary on beluga presence in the Chukchi during the summer, even the SAR demonstrates the arbitrary nature of NMFS' density calculations and the information upon which these calculations rely. The SAR for bowhead whales cites to a 2003 study that documented bowheads “in the Chukchi and Bering Seas in the summer” that are “thought to be a part of the expanding Western Arctic stock” (Angliss and Allen, 2009). While a study published in 2003 still is not a sufficient basis for a 2009 density analysis, this study does show that additional information is available that indicates that the number of bowhead whales in the Chukchi may be higher than estimated by NMFS.

Response:

As required by the MMPA implementing regulations at 50 CFR 216.102(a), NMFS has used the best scientific information available in assessing the level of take and whether it is negligible. The data presented in Moore

et al.

(2000b) was not derived from sightings on industry vessels. The paper relies on data collected over 10 years (1982-1991) from aerial surveys offshore of northern Alaska. AEWC does not provide a citation for the 2005 publication cited in the beluga SAR; however, NMFS assumes it is Suydam

et al.

(2005). This is a more recent paper that provides information on the movements of 23 tagged beluga whales in the Arctic Ocean basin. However, Suydam

et al.

(2005) do not provide any density calculations or information. Shell did reference this publication in section 4 of the IHA application when describing the distribution of beluga whales. Therefore, although this information was not used when deriving density or take estimates for beluga whales, this information was considered by NMFS in making its MMPA findings. Additionally, the 2003 study noted by AEWC in the bowhead whale SAR discusses distribution, not density (Rugh

et al.

, 2003). This paper is cited in the distribution discussion of bowhead whales in the Chukchi in section 4 of Shell's application. However, it is not useful for deriving density estimates. Therefore, density estimates for bowhead and beluga whales using Moore

et al.

(2000b) are based on the best available science.

Comment 53:

Dr. Moore notes that the last paragraph on page 25 of Shell's application states in part that “For the Chukchi Sea, cetacean densities during the summer (July-August) were estimated from effort and sightings data in Moore

et al.

(2000b).” Moore

et al.

(2000b) does provide summer Chukchi transect survey effort and sighting data (stratified by bathymetry) but only for gray whales. However, expected densities are listed for eight cetacean species. Since data for seven of these species cannot be referenced to Moore

et al.

(2000b), they must be calculated (somehow) from “data collected aboard industry vessels in 2006 and 2007.” However, to my knowledge, industry vessels never conducted surveys in a manner from which abundance can be estimated. NSB, AEWC, and Dr. Bain echo Dr. Moore's comment about using data from industry vessels for harbor porpoise. AEWC also states that the insufficiency of the harbor porpoise density estimate is compounded by NMFS' decision not to rely on data from “early autumn months” in calculating the “fall period” density of porpoises and to use “minimal values” instead, which is equally arbitrary.

Response:

The paragraph noted by the reviewer is meant to indicate to the reader the primary sources from which density information was derived. In the following paragraphs in the application (and in the Notice of Proposed IHA), additional information on the derivation of summer and fall densities for each species is provided. As Dr. Moore suggests, data on the effort and sightings of gray whales during summer surveys are reported in Moore

et al.

(2000b), and these data were used to estimate their expected density. Although not reported in the text or tables in Moore

et al.

(2000b), Figure 6 in the article indicates two on-transect sightings of beluga whales in the Chukchi Sea in the summer. These two sightings along with the survey effort for gray whales were used to calculate a summer beluga

whale density estimate for the Chukchi Sea. As explained in Shell's application, this same method was used to calculate a summer density of bowhead whales by assuming one sighting had occurred (although none were actually reported) during the reported survey effort for gray whales.

No published densities or data on survey efforts or sightings were available for harbor porpoise, but estimates had been calculated from industry survey data in 2006 and 2007, so those densities were used. The commenter is correct that the industry vessels did not conduct standard randomized line-transect surveys while operating (except for short periods in 2006). However, this information was considered the best scientific information available to determine a density estimate for harbor porpoise in the Chukchi Sea. As noted in the subsequent paragraphs in Shell's application, density or survey data for other cetacean species are either not available or have been reported in such low numbers that minimal densities were selected to account for chance encounters of these species that are less frequently observed in the area of Shell's operations in the Chukchi Sea. Additionally, for harbor porpoise, different density estimates were used for the summer and fall periods (see Tables 6-1 and 6-2 in Shell's application).

Comment 54:

Dr. Moore also notes that page 25 of Shell's application also states, “Because few data are available on the densities of marine mammals other than large cetaceans in the Chukchi Sea in the fall (Sep-Oct),

density estimates from the summer period have been adjusted

to reflect the expected ratio of summer-to-fall densities based on the natural history characteristics of each species” (emphasis added by commenter). Moore

et al.

(2000b) provides fall Chukchi data for bowhead, beluga, and gray whales, why is this not used? Even if these data were used, however, there remains the question of using sightings from industry vessels to “calculate densities” for five of the eight cetacean species listed in Table 6-2 of Shell's application. The MMC also recommends that NMFS require Shell to describe in detail how it adjusted the data in Moore

et al.

(2000b) to estimate cetacean densities in the Chukchi Sea in the fall.

Response:

Shell used the data from Moore

et al.

(2000b) to calculate densities for beluga and gray whales during the fall period in the Chukchi Sea, which is noted in subsequent paragraphs in the application. However, in order to be consistent with methods used to calculate bowhead densities in previous years, Moore

et al.

(2000b) was not used, although that data could have been used. See the response to comment 53 regarding deriving densities from industry vessels. In the absence of peer-reviewed literature, this was the best information available. Additional information on the use of correction factors and calculating density estimates is provided in the responses to several of the comments contained in this subsection of the document.

Comment 55:

AEWC states that NMFS fails to explain how and why it reaches various conclusions in calculating marine mammal densities and what the densities are actually estimated to be once calculated. One example is NMFS' reliance on Moore

et al.

(2000b) in making its density determinations. This study documented sightings of marine mammals but did not estimate the total number of animals present. NMFS fails to explain the basis for its “conversion” of data on sightings to its density conclusions.

Response:

All densities used in calculating estimated take of marine mammals based on the described operations are shown in Tables 6-1 and 6-2 of Shell's application. Moore

et al.

(2000b) provides line transect effort and sightings from aerial surveys for cetaceans in the Chukchi Sea. The kilometers of “on-transect” observer effort and number of sightings were used in the accepted line-transect density estimate equation described in Buckland

et al.

(2001). Species specific correction factors for animals that were not at the surface or that were at the surface but were not sighted [g(0)] and animals not sighted due to distance from the survey trackline [

f

(0)] used in the equation were taken from reports or publications on the same species or similar species if no values were available for a given species, that used the same survey platform. Additional explanations regarding the calculations of marine mammal densities are provided in the responses to other comments in this subsection of this document.

Comment 56:

NSB indicates that Shell's approach to estimating densities of beluga and bowhead whales is problematic. Shell uses densities from aerial surveys, which would be appropriate if bowheads and belugas were more or less stationary. In reality, the entire bowhead population and both stocks of belugas migrate through the area Shell proposes for its 2009 exploration activities. Thus, many more bowheads and belugas may potentially be taken during Shell's operations than what they have estimated. NMFS should carefully evaluate, and modify as appropriate, the approach Shell has used for estimating takes.

AWL also questions the use of a “density” measure in determining take in the Chukchi Sea during the bowhead migration. NMFS has recognized in the past that using density is inappropriate for determining bowhead take from seismic activities in the Beaufort Sea during the fall. It is not clear on what basis NMFS abandons an approach that would estimate migrating whales in the Chukchi Sea. Using a density calculation artificially reduces the number of bowheads that will likely be impacted from Shell's surveying and does not represent the best available science.

Response:

Shell's density estimates for bowhead and beluga whales are based on the best scientific information available, which is the standard required by the MMPA implementing regulations at 50 CFR 216.102(a). The alternative method referred to by AWL for estimating take of migrating bowhead whales was only used for seismic operations in the Beaufort Sea (and is described in Shell's IHA application in the Beaufort Sea Estimating Take Section; however, Shell cancelled the Beaufort Sea activities). This method has not been applied to activities in the Chukchi Sea. Because the migration corridor is narrower and better defined in the Beaufort Sea than the Chukchi Sea this method was deemed appropriate by NMFS for seismic operations in the Beaufort. However, the migratory path taken by bowhead whales once they enter the Chukchi Sea is not as well understood. Moreover, the migratory route is not as narrowly defined in the Chukchi. Additionally, if these species avoid areas of active seismic operations at levels lower than 160 dB re 1 μPa (rms), as noted by several of the commenters, then fewer animals will occur in the area of Shell's operations. After careful evaluation of the methods used by Shell to estimate take, NMFS has determined that Shell used the best scientific information available in calculating the take estimates.

Comment 57:

Dr. Bain notes that when estimating number of takes, it is important to consider if the individuals are feeding or migrating. In the case where there is little natural movement, the number of individuals in the ensonified area is an index of the number of takes. Exposed individuals can accumulate noise exposure or move out of the area. Assuming optimal foraging, displaced individuals will move to poorer feeding areas or compete with individuals for food in comparable habitat. When competition outside the

ensonified area occurs, the fitness of all individuals involved will be reduced, although only those exposed to noise are typically counted as taken.

Dr. Bain continues that when individuals are migrating through an area, new individuals are exposed to noise as they approach the noise source. Rather than estimating takes based on density in the ensonified area, it is more appropriate to draw a line across the ensonified area and estimate the number of individuals that would be expected to cross that line during the survey. Using an estimate of bowhead density from Funk

et al.

(2006) of 3/100 km

2

(3/38.6 mi2) in offshore waters in mid-season and a 120-dB diameter of 46 km (28.6 mi), Dr. Bain presents take numbers during the bowhead migration. Taking into account typical migration speed for bowhead whales (4.5 km reported in Koski

et al.

[2002]), in 24 hours, approximately 144 whales would either enter the ensonified area or be deflected to avoid it. As can be seen, the number of migrating whales exposed is far higher than would be the case if the sound source and whales were relatively stationary. Although not meant to be exact, the numbers used here are well within the range of possibilities and serve to illustrate that far more whales might be exposed during migration than during a feeding season.

Response:

Dr. Bain does not provide any scientific support for his theory. The temporary displacement of marine mammals from foraging habitat is not expected to affect individual fitness. For example, apparently, bowhead whales continued to increase in abundance during periods of intense seismic in the Chukchi Sea in the 1980s (Raftery

et al.

, 1995; Angliss and Allen, 2009), even without implementation of current mitigation requirements. NMFS is not certain what Dr. Bain means by “an index of the number of takes.”

NMFS does not agree with Dr. Bain's method for calculating takes of migrating bowhead whales. First, Dr. Bain uses the 120-dB level to estimate the level of take. For impulse sounds, such as from seismic airguns, NMFS uses the 160 dB re 1 μPa (rms) threshold to estimate Level B harassment. NMFS has responded several times over the past few years and elsewhere in this document to the assertion by commenters that Level B harassment takes should be estimated at the 120 dB level and not at the 160 dB level (see response to comment 25). Because Dr. Bain used this lower threshold, the take number presented is much higher than that generated by NMFS and Shell. Second, Dr. Bain uses a density estimate from Funk

et al.

(2006), which is based on industry monitoring. The public has expressed concern over the use of density estimates derived from industry monitoring (see other comments in this subsection). As explained in the response to comment 53, NMFS uses density estimates from peer reviewed journal articles when they are available. However, in instances when monitoring from industry vessels provide the only information, estimates are derived from those reports. However, in the case of bowhead whales, information is available from non-industry monitoring studies (e.g., Moore

et al.

(2000b)); therefore, the estimate provided in Funk

et al.

(2006) was not used. Additionally, Dr. Bain's calculation assumes that the whales will continue their entire migration along the same track as the seismic vessel. While some bowhead whales may occur in the action area, the migration corridor in the Chukchi Sea is not well defined. One cannot assume that the entire migration will occur near Shell's operations. Lastly, Dr. Bain's calculation also asserts that deflection itself constitutes a take. As explained elsewhere in this document, a minor course correction does not constitute a significant behavioral response rising to the level of a take. Therefore, NMFS does not agree that Dr. Bain's formula accurately portrays the number of bowhead whale takes during the fall migration period through the Chukchi Sea.

Comment 58:

Dr. Bain states that NMFS modeled takes in the Chukchi in September based on sightings in the Beaufort. However, the model is demonstrably inaccurate based on existing data from the Chukchi. Further, NMFS misinterpreted the data that form the basis of their extrapolation. Dr. Bain argues that the three reasons provided by NMFS for believing densities would be 20 times lower in the survey area than in the Beaufort in September are wrong. First, while it may be true to some degree that the migration corridor is narrower in the Beaufort, this is irrelevant. The reported density for the Beaufort depends on how well the survey design identifies the corridor boundary. Regardless of whether the average density is correctly identified, the density will vary across the corridor. That is, when the corridor widens, the average density will decline, but concentrations may still occur, as appears to be the case for the survey area (see plot in Moore

et al.

(2000b)).

Second, NMFS maintains that bowheads are more likely to migrate non-stop through the Chukchi in contrast to the Beaufort where they sometimes linger. As discussed in detail in Dr. Bain's letter (and comment 59), this will increase rather than decrease the number of whales taken. Third, NMFS states that most of the whales will migrate north of the survey area. To the contrary, the survey area is in the center of the migration route. Dr. Bain cites Quakenbush (2007), which shows a tagged bowhead whale migrating through Shell's survey area, and Moore

et al.

(2000b), which plotted bowhead sightings the same distance offshore as the survey area, not north of it. Finally, Funk

et al.

(2006) found many bowheads nearshore, not north of the survey area as anticipated by NMFS.

AWL states even accepting a density approach for the fall, we do not believe that the 95% discount applied by NMFS is appropriate. NMFS' .05 “correction factor” rests on the three points raised by Dr. Bain in this comment. AWL states that as discussed by Dr. Bain, these assertions do not justify such a severe reduction.

Response:

Although it would be preferable to estimate takes of marine mammals migrating through the Chukchi Sea using detailed data on migration location, timing, and rates, as exist for bowhead whales in the Beaufort Sea, no such data exist for any species in the Chukchi Sea. Applying data from the Beaufort Sea without adjustment to the Chukchi Sea, as suggested by the commenter, is also demonstrably inaccurate based on the evidence provided. Because specific migration data are lacking, the more common approach of using expected marine mammal densities to estimate takes in the Chukchi Sea was used. However, even basic density information on many species present in the Chukchi Sea during the open-water season are not available in the published literature.

In the case of bowhead whales, the most well documented density estimates, including

f

(0) and g(0) correction factors, are given in Richardson and Thomson (2002) for the Beaufort Sea, so this density was chosen as the starting point for estimating an expected density in the Chukchi Sea. The bowhead migration through the Chukchi Sea has been thought to bifurcate after passing Point Barrow. Recent data from the Alaska Department of Fish and Game (ADF&G 2009), which provides updated information of the tagging studies presented in Quakenbush (2007), suggest that a majority of bowheads travel through the northern Chukchi Sea to the Russian coast during the fall migration (approximately 90 percent) while a small number may travel southeast along the U.S. Chukchi Sea coast

(approximately 10 percent). Many of the animals traveling through the northern Chukchi Sea to the Russian coast appeared to travel north of Shell's Burger and Crackerjack prospects (the location for the 2009 site clearance and shallow hazards surveys). Although the sample size in the Beaufort Sea is somewhat smaller, the geographic distribution of migration paths through the Beaufort Sea does appear more restricted than through the northern Chukchi Sea (Quakenbush 2007; ADF&G 2009). Bowhead whale feeding areas have not been identified in or near lease holdings in the Chukchi Sea, so whales are not likely to concentrate at densities as high as those encountered by Richardson and Thomson (2002) in the Beaufort Sea, supporting a further reduction in the density used in the Chukchi Sea. These factors lead to the selection of a density that was 5 percent of the density reported by Richardson and Thomson (2002).

Comment 59:

AWL states that equally important is the lack of reasoning to support the final result. Although NMFS has provided some information as to why it applied a discount factor, it has not explained how it arrived at the precise figure. While some adjustment may be appropriate, NMFS does not include adequate information to demonstrate the basis for determin

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