2015-20605. Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to Geophysical and Geotechnical Survey in Cook Inlet, Alaska

AGENCY:

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

ACTION:

Notice; issuance of an incidental harassment authorization.

SUMMARY:

NMFS is issuing an Authorization in response to a request from ExxonMobil Alaska LNG LLC (EMALL) for an authorization to take marine mammals, by harassment, incidental to a geophysical and geotechnical survey in Cook Inlet, AK, for 84 days between August 14, 2015 and August 13, 2016.

DATES:

Effective August 14, 2015, through August 13, 2016.

ADDRESSES:

Electronic copies of the Incidental Harrassment Authorization (IHA; Authorization), application, and associated Environmental Assessment (EA) and Finding of No Significant Impact (FONSI) may be obtained by writing to Jolie Harrison, Division Chief, Permits and Conservation Division, Office of Protected Resources, National Marine Fisheries Service, 1315 East-West Highway, Silver Spring, MD 20910, telephoning the contact listed below (see FOR FURTHER INFORMATION CONTACT), or visiting the internet at: http://www.nmfs.noaa.gov/​pr/​permits/​incidental.htm. Documents cited in this notice may also be viewed, by appointment, during regular business hours, at the aforementioned address.

FOR FURTHER INFORMATION CONTACT:

Sara Young, Office of Protected Resources, NMFS, [phone].

SUPPLEMENTARY INFORMATION:

Background

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

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

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

Summary of Request

On February 4, 2015, NMFS received an application from EMALL for the taking of marine mammals incidental to a geotechnical and geophysical survey in Cook Inlet, Alaska. NMFS determined that the application was adequate and complete on June 8, 2015.

EMALL proposes to conduct a geophysical and geotechnical survey in Cook Inlet to investigate the technical suitability of a pipeline study corridor across Cook Inlet and potential marine terminal locations near Nikiski. The proposed activity would occur for 12 weeks during the 2015 open water season after August 14, 2015. The following specific aspects of the proposed activities are likely to result in the take of marine mammals: Use of a seismic airgun, sub-bottom profiler (chirp and boomer), and potentially a vibracore. Take, by Level B Harassment only, of individuals of four species of marine mammals is anticipated to result from the specified activities.

Description of the Specified Activity

Overview

The planned geophysical surveys involve remote sensors including single beam echo sounder, multibeam echo sounder, sub-bottom profiler (chirp and boomer), 0.983 L (60 in³) airgun, side scan sonar, geophysical resistivity meters, and magnetometer to characterize the bottom surface and subsurface. The planned shallow geotechnical investigations include vibracoring, sediment grab sampling, and piezo-cone penetration testing (PCPT) to directly evaluate seabed features and soil conditions. Geotechnical borings are planned at potential shoreline crossings and in the terminal boring subarea within the Marine Terminal survey area, and will be used to collect information on the mechanical properties of in-situ soils to support feasibility studies for construction crossing techniques and decisions on siting and design of pilings, dolphins, and other marine structures. Geophysical resistivity imaging will be conducted at the potential shoreline crossings. Shear wave velocity profiles (downhole geophysics) will be conducted within some of the boreholes. Further details of the planned operations are provided below.

Dates and Duration

Geophysical and geotechnical (G&G) surveys that do not involve equipment that could acoustically harass listed marine mammals began in May 2015. These surveys include echo sounders and side scan sonar surveys operating at frequencies above the hearing range of local marine mammals and geotechnical borings, which are not expected to produce underwater noise exceeding ambient. The remaining surveys, including use of sub-bottom profilers and the small airgun, will begin soon after receipt of the IHA. These activities would be scheduled in such a manner as to minimize potential effects to marine mammals, subsistence activities, and other users of Cook Inlet waters. It is expected that approximately 12 weeks (84 work days) are required to complete the G&G Program. The work days would not all be consecutive due to weather, rest days, and any timing restrictions.

Specified Geographic Region

The Cook Inlet 2015 G&G Program will include geophysical surveys, shallow geotechnical investigations, and geotechnical borings. Two separate areas will be investigated and are shown in Figure 1 of the application: The pipeline survey area and the Marine Terminal survey area (which includes an LNG carrier approach zone). The pipeline survey area runs from the Kenai Peninsula, across the Inlet, up to Beluga, also considered the Upper Inlet. The Terminal area will include an area west and south of Nikiski, the northern edge of what is considered the Lower Inlet. The G&G Program survey areas (also referred to as the action area or action areas) are larger than the proposed pipeline route and the Marine Terminal site to ensure detection of all potential hazards, or to identify areas free of hazards. This provides siting flexibility should the pipeline corridor or Marine Terminal sites need to be adjusted to avoid existing hazards.

• Pipeline Survey Area—The proposed pipeline survey area (Figure 1) crosses Cook Inlet from Boulder Point on the Kenai Peninsula across to Shorty Creek about halfway between the village of Tyonek and the Beluga River. This survey area is approximately 45 km (28 mi) in length along the corridor centerline and averages about 13 km (8 mi) wide. The total survey area is 541 km2 (209 mi2). The pipeline survey area includes a subarea where vibracores will be conducted in addition to the geophysical surveys and shallow geotechnical investigations.
• Marine Terminal Survey Area—The proposed Marine Terminal survey area (Figure 1), encompassing 371 km2 (143 mi2), is located near Nikiski where potential sites and vessel routes for the Marine Terminal are being investigated. The Marine Terminal survey area includes two subareas: A seismic survey subarea where the airgun will be operated in addition to the other geophysical equipment, and a terminal boring subarea where geotechnical boreholes will be drilled in addition to the geophysical survey and shallow geotechnical investigations. The seismic survey subarea encompasses 25 km2 (8.5 mi2) and the terminal boring subarea encompasses 12 km2 (4.6 mi2).

Detailed Description of Activities

The Notice of Proposed IHA (80 FR 37465, June 30, 2015) contains a full detailed description of the geotechnical and geophysical survey, including the sources proposed to be used and vessel details. That information has not changed and is therefore not repeated here.

Comments and Responses

A Notice of Proposed IHA was published in the Federal Register on June 30, 2015 (80 FR 37465) for public comment. During the 30-day public comment period, NMFS received four comment letters from the following: The Marine Mammal Commission (MMC); the Natural Resource Defense Counsel (NRDC); Friends of Animals (FOA); and one private citizen.

All of the public comment letters received on the Notice of Proposed IHA (80 FR 37465, June 30, 2015) are available on the internet at: http://www.nmfs.noaa.gov/​pr/​permits/​incidental.htm. Following is a summary of the public comments and NMFS' responses.

Comment 1: One private citizen requested that we deny issuance of the IHA because marine mammals would be killed as a result of the survey.

Response: The survey is not expected to result in the death of any marine mammal species, and no such take is authorized. Extensive analysis of the proposed geotechnical and geophysical survey was conducted in accordance with the MMPA, Endangered Species Act (ESA), and National Environmental Policy Act (NEPA). Pursuant to those statutes, we analyzed the impacts of the survey activities to marine mammals (including those listed as threatened or endangered under the ESA), their habitat (including critical habitat designated under the ESA), and to the availability of marine mammals for taking for subsistence uses. The MMPA analysis revealed that the activities would have a negligible impact on affected marine mammal species or stocks and would not have an unmitigable adverse impact on the availability of marine mammals for taking for subsistence uses. The ESA analysis concluded that the activities likely would not jeopardize the continued existence of ESA-listed species or destroy or adversely modify designated critical habitat. The NEPA analysis concluded that there would not be a significant impact on the human environment.

Comment 2: The MMC and the NRDC recommend that NMFS defer issuance of any Authorization to EMALL or other applicants until NMFS concludes that those activities would affect no more than a small number of Cook Inlet beluga whales with a negligible impact on the population.

Response: In accordance with our implementing regulations at 50 CFR 216.104(c), we use the best available scientific information to determine whether the taking by the specified activity within the specified geographic region will have a negligible impact on the species or stock and will not have an unmitigable adverse impact on the availability of such species or stock for subsistence uses. Based on the best scientific information available, NMFS determined that the impacts of the geotechnical and geophysical survey program, which are primarily acoustic in nature, would meet these standards. Moreover, EMALL proposed and NMFS has required in the IHA a rigorous mitigation plan to reduce impacts to Cook Inlet beluga whales and other marine mammals to the lowest level practicable, including measures to shutdown active acoustic sources if any beluga whale is observed approaching or within the Level B harassment zone and restricting activities within a 10 mi (16 km) radius of the Susitna Delta from April 15 through October 15, which is an important area for beluga feeding and calving in the spring and summer months. This shutdown measure is more restrictive than the standard shutdown measures typically applied, and combined with the Susitna Delta exclusion (minimizing adverse effects to foraging), is expected to reduce both the scope and severity of potential harassment takes, minimizing impacts from the harassment that would adversely affect reproductive rates or survivorship.

Our analysis indicates that issuance of this IHA will not contribute to or worsen the observed decline of the Cook Inlet beluga whale population. Additionally, the ESA Biological Opinion determined that the issuance of an IHA is not likely to jeopardize the continued existence of the Cook Inlet beluga whales or adversely modify Cook Inlet beluga whale critical habitat. The Biological Opinion also outlined Terms and Conditions and Reasonable and Prudent Measures to reduce impacts, which have been incorporated into the IHA. Therefore, based on the analysis of potential effects, the parameters of the survey, and the rigorous mitigation and monitoring program, NMFS determined that the activity would have a negligible impact on the population.

Moreover, the survey would take by Level B harrassment only small numbers of marine mammals relative to their population sizes. As described in the proposed IHA Federal Register notice, NMFS used a method that incorporates density of marine mammals overlaid with the anticipated ensonified area and the number of days of the operation to calculate an estimated number of takes for belugas. The number of belugas likely to be taken represents 7.04% of the population, which NMFS considers small. In addition to this quantitative evaluation, NMFS has also considered qualitative factors that further support the “small numbers” determination, including: (1) The seasonal distribution and habitat use patterns of Cook Inlet beluga whales, which suggest that for much of the time only a small portion of the population would be accessible to impacts from EMALL's activity, as most animals are concentrated in upper Cook Inlet; and (2) the mitigation requirements, which provide spatio-temporal limitations that avoid impacts to large numbers of animals feeding and calving in the Susitna Delta and limit exposures to sound levels associated with Level B harassment. Based on all of this information, NMFS determined that the number of beluga whales likely to be taken is small. See response to Comment 3 and our small numbers analysis later in this document for more information about the small numbers determination for beluga whales and the other marine mammal species.

Comment 3: The MMC recommends that before issuing any Authorizations, NMFS develop clear criteria for determining what constitutes small numbers and negligible impact for the purpose of authorizing incidental take of marine mammals.

Response: NMFS consistently assesses clearly articulated factors in making both the small numbers and negligible impact findings in our actions, and those findings are supported for this action as described in this notice. However, we are currently assessing our criteria for determining what constitutes “small numbers” and are working towards the development of an improved, and more quantitative, analytical framework for determining whether an activity will have a “negligible impact” for the purpose of authorizing takes of marine mammals. We fully intend to engage the MMC in these processes at the appropriate time.

Comment 4: The MMC and NRDC recommend that NMFS finalize and implement the beluga whale recovery plan, issue its programmatic EIS, and establish annual limits on the types of takes authorized for sound-producing activities in Cook Inlet before issuing additional Authorizations.

Response: NMFS recognizes the release of the draft recovery plan and, as an agency, will address and implement appropriate recommendations made in the recovery plan when the draft becomes a Final Recovery Plan, after NMFS has been able to incorporate public comment on the draft version.

Further, NMFS is making progress toward the development of the Cook Inlet EIS to analyze the environmental impacts of issuing Incidental Take Authorizations (ITAs) pursuant to the Marine Mammal Protection Act (MMPA) for the taking of marine mammals incidental to anthropogenic activities in the waters of Cook Inlet, AK, but in the meanwhile is also requesting that all Cook Inlet applicants requesting authorizations for the 2016 open water season send in their applications by October 1, 2015. This will enable NMFS to conduct a Programmatic EA for these activities and better analyze the cumulative effects from all of the authorizations proposed for each open water season until the EIS is complete.

Comment 5: The MMC, NRDC, and FOA commented on an error in beluga density information used to estimate the number of beluga exposures in the proposed authorization. The MMC and NRDC recommend that NMFS provide public notice of the revised number of beluga whale takes that NMFS proposes to authorize along with a revised analysis.

Response: NMFS acknowledges the error in beluga density information and has revised the calculations used for take estimation presented in the Federal Register notice for the proposed IHA. The correction results in a revised exposure estimate of 30 belugas. However, following discussions with the applicant, the MMC, and the Alaska Regional Office, NMFS has determined that exposures due to the chirp will not be included in the Authorization, as the chirp and the boomer will be operating concurrently and the 160-dB isopleth of the boomer is larger than that of the chirp. Therefore, NMFS is authorizing take by Level B harrassment of only 24 belugas. This new exposure estimate represents 7.06% of the population, whereas the original estimate of 14 represented 4.12% of the population. This difference does not substantively affect NMFS' analysis of effects, nor does it change the small numbers or negligible impact determinations, and therefore it does not merit a second public comment period.

Comment 6: The MMC and NRDC recommend that until behavior thresholds are updated, that NMFS require applicants to use the 120-dB rather than 160-dB threshold for sub-bottom profilers.

Response: The 120-dB threshold is typically associated with continuous sources. Continuous sounds are those whose sound pressure level remains above that of the ambient sound, with negligibly small fluctuations in level (NIOSH, 1998; ANSI, 2005). Intermittent sounds are defined as sounds with interrupted levels of low or no sound (NIOSH, 1998). Sub-bottom profiler signals are intermittent sounds. Intermittent sounds can further be defined as either impulsive or non-impulsive. Impulsive sounds have been defined as sounds which are typically transient, brief (<1 sec), broadband, and consist of a high peak pressure with rapid rise time and rapid decay (ANSI, 1986; NIOSH, 1998). Non-impulsive sounds typically have more gradual rise times and longer decays (ANSI, 1995; NIOSH, 1998). Sub-bottom profiler signals have durations that are typically very brief (<1 sec), with temporal characteristics that more closely resemble those of impulsive sounds than non-impulsive sounds. With regard to behavioral thresholds, we therefore consider the temporal and spectral characteristics of sub-bottom profiler signals to more closely resemble those of an impulse sound rather than a continuous sound. The 160-dB threshold is typically associated with impulsive sources.

The MMC suggests that, for certain sources considered here, the interval between pulses is so small it should be considered continuous. However, a sub-bottom profiler chirp's “rapid staccato” of pulse trains is emitted in a similar fashion as odontocete echolocation click trains. Research indicates that marine mammals, in general, have extremely fine auditory temporal resolution and can detect each signal separately (e.g., Au et al., 1988; Dolphin et al., 1995; Supin and Popov, 1995; Mooney et al., 2009), especially for species with echolocation capabilities. Therefore, it is highly unlikely that marine mammals would perceive sub-bottom profiler signals as being continuous.

In conclusion, sub-bottom profiler signals are intermittent rather than continuous signals, and the fine temporal resolution of the marine mammal auditory system allows them to perceive these sounds as such. Further, the physical characteristics of these signals indicate a greater similarity to the way that intermittent, impulsive sounds are received. Therefore, the 160-dB threshold (typically associated with impulsive sources) is more appropriate than the 120-dB threshold (typically associated with continuous sources) for estimating takes by behavioral harassment incidental to use of such sources.

We agree with the MMC'c recommendation to revise existing acoustic criteria and thresholds as necessary to specify threshold levels that would be more appropriate for a wider range of sound sources, and are currently in the process of producing such revisions. In particular, NMFS recognizes the importance of context (e.g., behavioral state of the animals, distance) in behavioral responses. The current behavioral categorization (i.e., impulse vs. continuous) does not account for context and is not appropriate for all sound sources. Thus, updated NOAA Acoustic Guidance (www.nmfs.noaa.gov/​pr/​acoustics/​guidelines.htm), once completed, will more appropriately categorize behavioral harassment criteria by activity type. NOAA recognizes, as new science becomes available, that our current categorizations (i.e., impulse vs. continuous) may not fully encompass the complexity associated with behavioral responses (i.e., context, etc.) and are working toward addressing these issues in future acoustic guidance. However, in the meanwhile, while our current behavioral acoustic thresholds may not fully account for some of the differences observed across taxa and contexts, they still serve as somewhat conservative generalized indicators of received levels at which we anticipate behavioral harassment, and are not undermined by newer information.

Comment 7: The MMC and NRDC recommend that prior to issuance of the Final Authorization, NMFS include taking by Level B harassment of humpback whales, gray whales, minke whales, Dall's porpoise, and Steller sea lion.

Response: The issuance of an Authorization to an applicant is a request-based process. On the one hand, if NMFS believes that marine mammals will be taken that are not identified by the applicant, we will work with the applicant to modify the request to ensure inclusion of affected species. On the other hand, applicants sometimes request take of a small number of species that NMFS believes are unlikely to be encountered but NMFS will authorize take of those species as long as the necessary findings can be made. NMFS acknowledges that it has authorized the take of the species identified by commenters that occur infrequently in Cook Inlet in other Authorizations. However, in those instances, the applicant requested take of those species and NMFS analyzed the requests submitted. EMALL believes, and NMFS concurs, that with the required monitoring, small zones of influence, and short operating period (as compared to previous activities authorized in Cook Inlet), the activities are unlikely to result in the take any of the species identified by the commenters. Moreover, if a species for which take is not authorized is encountered, the Authorization text states that the applicant must shut down active sound sources.

Comment 8: The MMC recommends that NMFS require EMALL to monitor for marine mammals for 30 minutes after authorized activities have ceased.

Response: NMFS agrees with the MMC and has added a post-activity monitoring period of 30 minutes as a requirement for this activity. A 30-minute monitoring period after the cessation of authorized sound source operations can provide useful observations to compare the behavior and abundance of animals during different scenarios of various noise levels. This change has been noted in the Authorization text.

Comment 9: The MMC and NRDC recommend that NMFS allow sufficient time between the close of the comment period and issuance of an Authorization for NMFS to analyze, consider, and respond fully to comments received and incorporate changes as appropriate.

Response: NMFS acknowledges that the time between the close of public comment and the target date for issuing the Authorization is short. However, NMFS fully considered and responded to all comments before issuing the Authorization, and incorporated changes as appropriate (i.e., see response to Comment 8).

Comment 10: The NRDC and FOA comment that NEPA mandates that NMFS may not authorize activities while a programmatic EIS is underway. The NRDC references 40 CFR 1506.1.

Response: NMFS acknowledges that it is preparing an EIS for incidental take authorizations in Cook Inlet, AK (79 FR 61616; October 14, 2014). However, NMFS is undertaking this environmental analysis voluntarily as a decision support tool for processing MMPA ITA requests in Cook Inlet. The programmatic EIS is meant to address anticipated future levels of activity in Cook Inlet, which may include increases in activity, not a specific proposed program or project. NMFS will continue to prepare EAs or EISs, as appropriate, for specific individual applications for Incidental Take Authorizations (ITA) at this time. Consistent with its obligations under NEPA, NMFS prepared an EA (including an analysis of cumulative effects) prior to issuing the Authorization to EMALL and determined that issuance of the Authorization would not significantly impact the quality of the human environment.

Comment 11: The NRDC commented that NMFS should not issue an Authorization until it has completed its revision of acoustic thresholds for take by Level B harrassment.

Response: NMFS notes that NRDC's comment that NMFS uses an outdated and incorrect threshold for behavioral takes does not include any specific recommendations. NMFS uses 160 dB (rms) as the exposure level for estimating take by Level B harassment for most species in most cases. This threshold was established for underwater impulse sound sources based on measured avoidance responses observed in whales in the wild. Specifically, the 160 dB threshold was derived from data for mother-calf pairs of migrating gray whales (Malme et al., 1983, 1984) and bowhead whales (Richardson et al., 1985, 1986) responding to seismic airguns (e.g., impulsive sound source). There is more recent information bearing on behavioral reactions to seismic airguns, but while those data illustrate how complex and context-dependent the relationship is between the two, they do not clearly suggest that there is a more appropriate level than 160dB to serve as general behavioral harassment threshold for multiple taxa. See 75 FR 49710, 49716 (August 13, 2010) (IHA for Shell seismic survey in Alaska). Further, it is not a matter of merely replacing the existing threshold with a new one. NOAA is working to develop more sophisticated draft guidance for determining impacts from acoustic sources, including information for determining Level B harassment thresholds. Due to the complexity of the task, any guidance will require a rigorous review that includes internal agency review, public notice and comment, and additional external peer review before any final product is published. In the meantime, and taking into consideration the facts and available science, NMFS determined it is reasonable to use the 160 dB threshold for estimating takes of marine mammals in Cook Inlet by Level B harassment. However, we discuss the science on this issue qualitatively in our analysis of potential effects to marine mammals.

Comment 12: The NRDC comments that NMFS should require the use of alternative technologies, including quieting technologies, as well as adopting additional time-area closures.

Response: NMFS responds to this comment as part of the response to Comment 14 below.

Comment 13: The NRDC comments that the suggestion that Cook Inlet belugas are habituated to certain levels of anthropogenic activity is outdated, given a study by Kendall et al. (2014) on impacts to belugas from construction noise.

Response: NMFS acknowledges that there are scientific records of belugas responding to anthropogenic noise, as evidenced in Kendall et al. (2014). Beluga whale response to vessel noise varies greatly from tolerance to extreme sensitivity depending on the activity of the whale and previous experience with vessels (Richardson et al., 1995). Reactions to vessels depends on whale activities and experience, habitat, boat type, and boat behavior (Richardson et al., 1995), and may include behavioral responses, such as altered headings or avoidance (Blane and Jaakson, 1994; Erbe and Farmer, 2000); fast swimming; changes in vocalizations (Lesage et al., 1999; Scheifele et al., 2005); and changes in dive, surfacing, and respiration patterns.

A study by Lessage et al. (1999) of belugas in the St. Lawrence River states with respect to modification of vocal behavior that “Owing to the gregarious nature of belugas, this would not pose a serious problem for intraherd communication, given the relatively short distances between herd members; a source of noise would have to be very close to them to potentially limit any communication within a herd. However, communication is probably not limited to herd members, since inter-herd communication may be important during the breeding season, when locating food sources, when navigating in ice, or when reacting to large-scale disturbance. On these larger scales, high noise levels could impair communication.” NMFS acknowledges the potential for masking from the sound sources proposed by EMALL and discusses the potential effects of this. The concerns raised by NRDC in the paper by Bejder et al. (2009), that animals that do not display overt behavioral reactions could be incurring harm, is an important component of understanding the effects of tolerance on mammals in areas of increasing anthropogenic activity but no mechanism to estimate the physiological effects from tolerance are currently viable for this analysis. As noted above, though, even though shutdown measures are in place that will minimize behavioral harassment of belugas, NMFS does not reduce the amount of take expected/authorized due to possible habitation of belugas in Cook Inlet to anthropogenic noise, and the negligible impact determination below does not rely on an assumption of habitation to make the necessary findings.

Comment 14: The NRDC comments that NMFS is failing to meet the requirement of setting forth “permissible methods of taking pursuant to such activity, and other means of effecting the least practicable adverse impact on such species or stock and its habitat” and urges NMFS to adopt meaningful mitigation and monitoring measures including requiring applicants to contribute to a comprehensive monitoring plan to better understand distribution as well as individual and cumulative effects of human activities on Cook Inlet belugas, which was incorporated by reference to NRDC's public comment on the Proposed Rule for Apache Alaska Corporation. In the Apache comment letter, the NRDC provides a list of approximately eight measures that NMFS “failed to consider or adequately consider.”

Response: NMFS provided a detailed discussion of proposed mitigation measures and the MMPA's “least practicable impact” standard in the notice of the proposed IHA (80 FR 37465, June 30, 2015), which are repeated in the “Mitigation” section of this notice. The measures that NRDC alleges NMFS failed to consider or adequately consider are identified and discussed below:

(1) Field testing and use of alternative technologies, such as vibroseis and gravity gradiometry, to reduce or eliminate the need for airguns and delaying seismic acquisition in higher density areas until the alternative technology of marine vibroseis becomes available: EMALL requested takes of marine mammals incidental to the geotechnical and geophysical survey operations described in the IHA application, which identified use of only a 60 in³ airgun array with a distance to the 160-dB isopleth of 300m. It would be inappropriate for NMFS to fundamentally change the specified activity for which EMALL submitted an IHA application by requiring that they acquire data using an entirely different system of sound sources, especially if the alternate technology cannot meet the objectives of the proposed activity.

EMALL knows of no current technology scaled for industrial use that is reliable enough to meet the environmental challenges of operating in Cook Inlet. An airgun is only one of several sources proposed by EMALL and alternative quieting technologies for the boomer, chirp, and vibracore are undeveloped at this time.

(2) Required use of the lowest practicable source level in conducting airgun activity: EMALL is requesting to use a 60 in³ airgun, a very small source, for a duration of 7 days. This size of airgun, and the length and area of the survey, is necessary to meet EMALL's program objectives and minimize geotechnical, geohazard, and constructability risks.

(3) Seasonal exclusions around river mouths, including early spring (pre-April 14) exclusions around the Beluga River and Susitna Delta, and avoidance of other areas that have a higher probability of beluga occurrence: NMFS has required a 10 mile (16 km) exclusion zone around the Susitna Delta (which includes the Beluga River) in this IHA. Survey operations involving the use of airgun, boomer, chirp, and vibracore will be prohibited in this area between April 15 and October 15. In both the MMPA and ESA analysis, NMFS determined that this date range is sufficient to protect Cook Inlet beluga whales and the critical habitat in the Susitna Delta. While data indicate that belugas may use this part of the inlet year round, peak use occurs from early May to late September. NMFS added a 2-week buffer on both ends of this peak usage period to add extra protection to feeding and calving belugas.

(4) Limitation of the mitigation airgun to the longest shot interval necessary to carry out its intended purpose: EMALL is not proposing to use a mitigation airgun, therefore this measure does not apply.

(5) Immediate suspension of airgun activity, pending investigation, if any beluga strandings occur within or within an appropriate distance of the survey area: The IHA requires EMALL to immediately cease activities and report unauthorized takes of marine mammals, such as live stranding, injury, serious injury, or mortality. NMFS will review the circumstances of EMALL's unauthorized take and determine if additional mitigation measures are needed before activities can resume to minimize the likelihood of further unauthorized take and to ensure MMPA compliance. EMALL may not resume activities until notified by NMFS. Separately, the IHA includes measures if injured or dead marine mammals are sighted and the cause cannot be easily determined. In those cases, NMFS will review the circumstances of the stranding event while EMALL continues with operations.

(6) Establishment of a larger exclusion zone for beluga whales that is not predicated on the detection of whale aggregations or cow-calf pairs: Both the proposed IHA and the issued IHA contain a requirement for EMALL to delay the start of active acoustic source use or shutdown the active acoustic sources if a beluga whale is visually sighted approaching or within the 160-dB disturbance zone until the animal(s) are no longer present within the 160-dB zone. The measure applies to the sighting of any beluga whale, not just sighting of groups or cow-calf pairs.

Comment 15: FOA comments on several issues related to cumulative impacts analysis including: (1) NMFS contradicts the Draft Recovery Plan by issuing Authorizations, given that two concerns of note in the Plan include noise and cumulative/synergistic effects (2) each phase of the Alaska LNG project will add to increasing cumulative effects to Cook Inlet belugas (3) over the past three years, NMFS has authorized at least 288 takes by Level B harassment of Cook Inlet beluga whales and that takes for AK LNG must be addressed in the context of cumulative impacts from other authorized takes.

Response: Neither the MMPA nor NMFS' implementing regulations specify how to consider other activities and their impacts on the same populations when conducting a negligible impact analysis. However, consistent with the 1989 preamble for NMFS' implementing regulations (54 FR 40338, September 29, 1989), the impacts from other past and ongoing anthropogenic activities are incorporated into the negligible impact analysis via their impacts on the environmental baseline (e.g., as reflected in the density/distribution and status of the species, population size and growth rate, and ambient noise).

Although caution is warranted for noise-producing activities, especially in light of all of the other activities in Cook Inlet, NMFS does not agree that issuance of any Authorizations for take of Cook Inlet beluga whales is contradictory to recommendations in the Draft Recovery Plan for this species. NMFS is taking a cautious approach, both in the context of this particular project and Cook Inlet more broadly, to ensure that all impacts on beluga whales are adequately analyzed and minimized. For example, the shutdown of active sound sources at the 160-dB disturbance zone for beluga whales in Cook Inlet is a precautionary measure not used in other areas to ensure the minimization of behavioral harassment of belugas. Additionally, a precautionary approach was taken in estimating the number of exposures from the proposed EMALL survey, which is likely an overestimate of individuals taken for reason explained below in the `Take Estimation” section related to number of individuals taken versus instances of exposure.

More broadly, NMFS has announced our intent to prepare an EIS to better analyze cumulative impacts from potential increasing anthropogenic activities to Cook Inlet beluga whales. In addition, cumulative effects were addressed in the EA and Biological Opinion prepared for this action. The cumulative effects section of the EA has been expanded from the draft EA to discuss potential effects in greater detail. These documents, as well as the Alaska Marine Stock Assessments and the most recent abundance estimate for Cook Inlet beluga whales (Shelden et al, 2015), are part of NMFS' Administrative Record for this action, and provided the decision maker with information regarding other activities in the action area that affect marine mammals, an analysis of cumulative impacts, and other information relevant to the determination made under the MMPA.

NMFS will continue to analyze monitoring reports from authorized activities, applicable new science, and the increase of Cook Inlet activities in the context of the Cook Inlet Beluga Whale Recovery Plan, and will also continue to carefully evaluate proposed activities and recommend mitigation measures to ensure that the issuance of MMPA authorizations does not negatively impact the recovery of Cook Inlet belugas.

Comment 16: FOA comments that the Environmental Assessment (EA) was difficult to find and recommends that NMFS re-open the public comment period for the EA as well as the Draft Recovery Plan for Cook Inlet belugas.

Response: NMFS posted a draft of the EA on its Web site for public review: http://www.nmfs.noaa.gov/​pr/​permits/​incidental/​energy_​other.htm. On July 6th, the MMC notified NMFS that the documents were placed under “Other” and not “Natural Gas” on the Web site. Once notified, NMFS corrected the error. During and after that time NMFS received no other communication from any persons or organizations requesting to be directed to those documents or asking for clarification as to their location. Therefore, NMFS does not believe the EA should be reopened for public comment. The Draft Recovery Plan for Cook Inlet beluga whales is a separate action and the reopening of its comment period is not relevant to this Authorization.

Comment 17: FOA comments that the Marine Terminal area lies within beluga Critical Habitat. FOA also comments that effects on habitat could include disturbance to prey from noise, and disturbances to the environment from the platform's legs and project discharges from sampling activities.

Response: The Federal Register notice of the proposed Authorization analyzed potential effects to prey species and marine mammal habitat. The possibility of adverse modification to Critical Habitat through reduction in prey species is addressed in the Biological Opinion, which resulted in a finding of no adverse modification to critical habitat.

Comment 20: FOA comments that issuance of an IHA to EMALL would violate the ESA because granting the IHA would “appreciably reduce the likelihood of survival and recovery of species in the wild.”

Response: NMFS disagrees with FOA's comment. NMFS Office of Protected Resources (Permits and Conservation Division) initiated and engaged in formal consultation with NMFS Alaska Regional Office (Protected Resources Division) under section 7 of the ESA on the issuance of the IHA to EMALL. NMFS's Biological Opinion concluded that the issuance of the IHA is not likely to jeopardize the continued existence of listed species (e.g., would not appreciably reduce the ability of any listed species under NMFS' jurisdiction to survive and recover in the wild) or result in the destruction or adverse modification of critical habitat.

Comment 21: FOA comments that NMFS must include a discussion of ethics and the rights of wildlife to manage wildlife-human interactions and suggests that this approach is consistent with NEPA and the ability to provide a “full and fair discussion” of the issues and inform decision makes and the public of the reasonable alternatives that would avoid or minimize adverse impacts or enhance the quality of the human environment. 40 CFR 1502.1.

Response: Consistent with the requirements of NEPA and CEQ's implementing regulations, NMFS prepared an Environmental Assessment prior to issuing an IHA to EMALL that includes a comprehensive assessment of the effects of this action and alternative actions on the human environment, including the impacts of the action and alternative actions on marine mammal populations. While NMFS shares FAO's concerns regarding the ethical treatment of animals, it is not possible to directly address ethical treatment in the context of incidental and unintended effects (i.e., those authorized by this action), as any pain resulting from these impacts is far removed from any operator decisions and is neither observable, measurable or controllable. Instead, IHAs aim to minimize actual adverse effects to marine mammal individuals and populations.

Description of Marine Mammals in the Area of the Specified Activity

Marine mammals that regularly inhabit upper Cook Inlet and Nikiski activity areas are the beluga whale (Delphinapterus leucas), harbor porpoise (Phocoena phocoena), and harbor seal (Phoca vitulina) (Table 6). However, these species are found there in relatively low numbers, and generally only during the summer fish runs (Nemeth et al. 2007, Boveng et al. 2012). Killer whales (Orcinus orca) are occasionally observed in upper Cook Inlet where they have been observed attempting to prey on beluga whales (Shelden et al. 2003). Based on a number of factors, Shelden et al. (2003) concluded that the killer whales found in upper Cook Inlet to date are the transient type, while resident types occasionally enter lower Cook Inlet. Marine mammals occasionally found in lower Cook Inlet include humpback whales (Megaptera novaeangliae), gray whales (Eschrichtius robustus), minke whales (Balaenoptera acutorostrata), Dall's porpoise (Phocoena dalli), and Steller sea lion (Eumetopias jubatus). Background information of species evaluated in this Authorization is detailed in Table 1 below.

Table 1—Marine Mammals Inhabiting the Cook Inlet Action Area

Species	Stock	ESA/MMPA status 1; strategic (Y/N)	Stock abundance (CV, Nmin, most recent abundance survey) 2	Relative occurrence in Cook Inlet; season of occurrence
Killer whale	Alaska Resident Alaska Transient	-;N -:N	2,347 (N/A; 2,084; 2009) 345 (N/A; 303; 2003)	Occasionally sighted in Lower Cook Inlet.
Beluga whale	Cook Inlet	E/D;Y	312 (0.10; 280; 2012)	Use upper Inlet in summer and lower in winter: annual.
Harbor porpoise	Gulf of Alaska	-;Y	31,046 (0.214; 25,987; 1998)	Widespread in the Inlet: annual (less in winter).
Harbor seal	Cook Inlet/Shelikof	-;N	22,900 (0.053; 21,896; 2006)	Frequently found in upper and lower inlet; annual (more in northern Inlet in summer).

Beluga Whale (Delphinapterus leucas)

The Cook Inlet beluga whale Distinct Population Segment (DPS) is a small geographically isolated population that is separated from other beluga populations by the Alaska Peninsula. The population is genetically (mtDNA) distinct from other Alaska populations, suggesting that the Peninsula is an effective barrier to genetic exchange (O'Corry-Crowe et al. 1997) and that these whales may have been separated from other stocks at least since the last ice age. Laidre et al. (2000) examined data from over 20 marine mammal surveys conducted in the northern Gulf of Alaska and found that sightings of belugas outside Cook Inlet were exceedingly rare, and these were composed of a few stragglers from the Cook Inlet DPS observed at Kodiak Island, Prince William Sound, and Yakutat Bay. Several marine mammal surveys specific to Cook Inlet (Laidre et al. 2000, Speckman and Piatt 2000), including those that concentrated on beluga whales (Rugh et al. 2000, 2005a), clearly indicate that this stock largely confines itself to Cook Inlet. There is no indication that these whales make forays into the Bering Sea where they might intermix with other Alaskan stocks.

The Cook Inlet beluga DPS was originally estimated at 1,300 whales in 1979 (Calkins 1989) and has been the focus of management concerns since experiencing a dramatic decline in the 1990s. Between 1994 and 1998 the stock declined 47%, which has been attributed to overharvesting by subsistence hunting. During that period, subsistence hunting was estimated to have annually removed 10-15% of the population. Only five belugas have been harvested since 1999, yet the population has continued to decline (Allen and Angliss 2014), with the most recent estimate at only 312 animals (Allen and Angliss 2014). The NMFS listed the population as “depleted” in 2000 as a consequence of the decline, and as “endangered” under the ESA in 2008 when the population failed to recover following a moratorium on subsistence harvest. In April 2011, the NMFS designated critical habitat for the Cook Inlet beluga whale under the ESA (Figure 2 in the application).

Prior to the decline, this DPS was believed to range throughout Cook Inlet and occasionally into Prince William Sound and Yakutat (Nemeth et al. 2007). However, the range has contracted coincident with the population reduction (Speckman and Piatt 2000). During the summer and fall, beluga whales are concentrated near the Susitna River mouth, Knik Arm, Turnagain Arm, and Chickaloon Bay (Nemeth et al. 2007) where they feed on migrating eulachon (Thaleichthys pacificus) and salmon (Onchorhynchus spp.) (Moore et al. 2000). The limits of Critical Habitat Area 1 reflect the summer distribution (Figure 3 in the application). During the winter, beluga whales concentrate in deeper waters in the mid-inlet to Kalgin Island, and in the shallow waters along the west shore of Cook Inlet to Kamishak Bay. The limits of Critical Habitat Area 2 reflect the winter distribution. Some whales may also winter in and near Kachemak Bay.

Goetz et al. (2012) modeled beluga use in Cook Inlet based on the NMFS aerial surveys conducted between 1994 and 2008. The combined model results shown in Figure 3 in the application indicate a very clumped distribution of summering beluga whales, and that lower densities of belugas are expected to occur in most of the pipeline survey area (but not necessarily specific G&G survey locations; see Section 6.3 in the application) and the vicinity of the proposed Marine Terminal. However, Cook Inlet beluga whales begin moving into Knik Arm around August 15 where they spend about a month feeding on Eagle River salmon. The area between Nikiski, Kenai, and Kalgin Island provides important wintering habitat for Cook Inlet beluga whales. Use of this area would be expected between fall and spring, with animals largely absent during the summer months when G&G surveys would occur (Goetz et al. 2012).

Killer Whale (Orcinus orca)

Two different stocks of killer whales inhabit the Cook Inlet region of Alaska: The Alaska Resident Stock and the Gulf of Alaska, Aleutian Islands, Bering Sea Transient Stock (Allen and Angliss 2014). The Alaska Resident killer whale stock is estimated at 2,347 animals and occurs from Southeast Alaska to the Bering Sea (Allen and Angliss 2014). Resident killer whales feed exclusively on fish and are genetically distinct from transient whales (Saulitis et al. 2000).

The transient killer whales feed primarily on marine mammals (Saulitis et al. 2000). The transient population inhabiting the Gulf of Alaska shares mitochondrial DNA haplotypes with whales found along the Aleutian Islands and the Bering Sea, suggesting a common stock, although there appears to be some subpopulation genetic structuring occurring to suggest the gene flow between groups is limited (see Allen and Angliss 2014). For the three regions combined, the transient population has been estimated at 587 animals (Allen and Angliss 2014).

Killer whales are occasionally observed in lower Cook Inlet, especially near Homer and Port Graham (Shelden et al. 2003, Rugh et al. 2005a). The few whales that have been photographically identified in lower Cook Inlet belong to resident groups more commonly found in nearby Kenai Fjords and Prince William Sound (Shelden et al. 2003). Prior to the 1980s, killer whale sightings in upper Cook Inlet were very rare. During aerial surveys conducted between 1993 and 2004, killer whales were observed on only three flights, all in the Kachemak and English Bay area (Rugh et al. 2005a). However, anecdotal reports of killer whales feeding on belugas in upper Cook Inlet began increasing in the 1990s, possibly in response to declines in sea lion and harbor seal prey elsewhere (Shelden et al. 2003). These sporadic ventures of transient killer whales into beluga summering grounds have been implicated as a possible contributor to the decline of Cook Inlet belugas in the 1990s, although the number of confirmed mortalities from killer whales is small (Shelden et al. 2003). If killer whales were to venture into upper Cook Inlet in 2015, they might be encountered during the G&G Program.

Harbor Porpoise (Phocoena phocoena)

Harbor porpoise are small (approximately 1.2 m [4 ft] in length), relatively inconspicuous toothed whales. The Gulf of Alaska Stock is distributed from Cape Suckling to Unimak Pass and was most recently estimated at 31,046 animals (Allen and Angliss 2014). They are found primarily in coastal waters less than 100 m (328 ft) deep (Hobbs and Waite 2010) where they feed on Pacific herring (Clupea pallasii), other schooling fishes, and cephalopods.

Although they have been frequently observed during aerial surveys in Cook Inlet, most sightings of harbor porpoise are of single animals, and are concentrated at Chinitna and Tuxedni bays on the west side of lower Cook Inlet (Rugh et al. 2005a). Dahlheim et al. (2000) estimated the 1991 Cook Inlet-wide population at only 136 animals. Also, during marine mammal monitoring efforts conducted in upper Cook Inlet by Apache from 2012 to 2014, harbor porpoise represented less than 2% of all marine mammal sightings. However, they are one of the three marine mammals (besides belugas and harbor seals) regularly seen in upper Cook Inlet (Nemeth et al. 2007), especially during spring eulachon and summer salmon runs. Because harbor porpoise have been observed throughout Cook Inlet during the summer months, including mid-inlet waters, they represent species that might be encountered during G&G Program surveys in upper Cook Inlet.

Harbor Seal (Phoca vitulina)

At over 150,000 animals state-wide (Allen and Angliss 2014), harbor seals are one of the more common marine mammal species in Alaskan waters. They are most commonly seen hauled out at tidal flats and rocky areas. Harbor seals feed largely on schooling fish such as Alaska Pollock, Pacific cod, salmon, Pacific herring, eulachon, and squid. Although harbor seals may make seasonal movements in response to prey, they are resident to Alaska and do not migrate.

The Cook Inlet/Shelikof Stock, ranging from approximately Anchorage down along the south side of the Alaska Peninsula to Unimak Pass, has been recently estimated at a stable 22,900 (Allen and Angliss 2014). Large numbers concentrate at the river mouths and embayments of lower Cook Inlet, including the Fox River mouth in Kachemak Bay (Rugh et al. 2005a). Montgomery et al. (2007) recorded over 200 haulout sites in lower Cook Inlet alone. However, only a few dozen to a couple hundred seals seasonally occur in upper Cook Inlet (Rugh et al. 2005a), mostly at the mouth of the Susitna River where their numbers vary with the spring eulachon and summer salmon runs (Nemeth et al. 2007, Boveng et al. 2012). Review of NMFS aerial survey data collected from 1993-2012 (Shelden et al. 2013) finds that the annual high counts of seals hauled out in Cook Inlet ranged from about 100-380, with most of these animals hauling out at the mouths of the Theodore and Lewis Rivers. There are certainly thousands of harbor seals occurring in lower Cook Inlet, but no references have been found showing more than about 400 harbor seals occurring seasonally in upper Cook Inlet. In 2012, up to 100 harbor seals were observed hauled out at the mouths of the Theodore and Lewis rivers (located about 16 km [10 mi] northeast of the pipeline survey area) during monitoring activity associated with Apache's 2012 Cook Inlet seismic program, and harbor seals constituted 60 percent of all marine mammal sightings by Apache observers during 2012 to 2014 survey and monitoring efforts (L. Parker, Apache, pers. comm.). Montgomery et al. (2007) also found that seals elsewhere in Cook Inlet move in response to local steelhead (Onchorhynchus mykiss) and salmon runs. Harbor seals may be encountered during G&G surveys in Cook Inlet.

Humpback Whale (Megaptera novaeangliae)

Although there is considerable distributional overlap in the humpback whale stocks that use Alaska, the whales seasonally found in lower Cook Inlet are probably of the Central North Pacific stock. Listed as endangered under the ESA, this stock has recently been estimated at 7,469, with the portion of the stock that feeds in the Gulf of Alaska estimated at 2,845 animals (Allen and Angliss 2014). The Central North Pacific stock winters in Hawaii and summers from British Columbia to the Aleutian Islands (Calambokidis et al. 1997), including Cook Inlet.

Humpback use of Cook Inlet is largely confined to lower Cook Inlet. They have been regularly seen near Kachemak Bay during the summer months (Rugh et al. 2005a), and there is a whale-watching venture in Homer capitalizing on this seasonal event. There are anecdotal observations of humpback whales as far north as Anchor Point, with recent summer observations extending to Cape Starichkof (Owl Ridge 2014). Because of the southern distribution of humpbacks in Cook Inlet, it is unlikely that they will be encountered during this activity in close enough proximity to cause Level B harassment. Therefore, no take is authorized for humpback whales.

Gray Whale (Eschrichtius robustus)

Each spring, the Eastern North Pacific stock of gray whale migrates 8,000 kilometers (5,000 miles) northward from breeding lagoons in Baja California to feeding grounds in the Bering and Chukchi seas, reversing their travel again in the fall (Rice and Wolman 1971). Their migration route is for the most part coastal until they reach the feeding grounds. A small portion of whales do not annually complete the full circuit, as small numbers can be found in the summer feeding along the Oregon, Washington, British Columbia, and Alaskan coasts (Rice et al. 1984, Moore et al. 2007).

Human exploitation reduced this stock to an estimated “few thousand” animals (Jones and Schwartz 2002). However, by the late 1980s, the stock was appearing to reach carrying capacity and estimated to be at 26,600 animals (Jones and Schwartz 2002). By 2002, that stock had been reduced to about 16,000 animals, especially following unusually high mortality events in 1999 and 2000 (Allen and Angliss 2014). The stock has continued to grow since then and is currently estimated at 19,126 animals with a minimum estimate of 18,017 (Carretta et al. 2013). Most gray whales migrate past the mouth of Cook Inlet to and from northern feeding grounds. However, small numbers of summering gray whales have been noted by fisherman near Kachemak Bay and north of Anchor Point. Further, summering gray whales were seen offshore of Cape Starichkof by marine mammal observers monitoring Buccaneer's Cosmopolitan drilling program in 2013 (Owl Ridge 2014). Regardless, gray whales are not expected to be encountered in upper Cook Inlet, where the activity is concentrated, north of Kachemak Bay. Therefore, it is unlikely that they will be encountered during this activity in close enough proximity to cause Level B harassment and are not considered further in this final Authorization notice.

Minke Whale (Balaenoptera acutorostrata)

Minke whales are the smallest of the rorqual group of baleen whales reaching lengths of up to 35 feet. They are also the most common of the baleen whales, although there are no population estimates for the North Pacific, although estimates have been made for some portions of Alaska. Zerbini et al. (2006) estimated the coastal population between Kenai Fjords and the Aleutian Islands at 1,233 animals.

During Cook Inlet-wide aerial surveys conducted from 1993 to 2004, minke whales were encountered only twice (1998, 1999), both times off Anchor Point 16 miles northwest of Homer. Recently, several minke whales were recorded off Cape Starichkof in early summer 2013 during exploratory drilling conducted there (Owl Ridge 2014). There are no records north of Cape Starichkof, and this species is unlikely to be seen in upper Cook Inlet. There is little chance of encountering a minke whale during these activities. Therefore, no take of minke whales is authorized.

Dall's Porpoise (Phocoenoides dalli)

Dall's porpoise are widely distributed throughout the North Pacific Ocean including Alaska, although they are not found in upper Cook Inlet and the shallower waters of the Bering, Chukchi, and Beaufort Seas (Allen and Angliss 2014). Compared to harbor porpoise, Dall's porpoise prefer the deep offshore and shelf slope waters. The Alaskan population has been estimated at 83,400 animals (Allen and Angliss 2014), making it one of the more common cetaceans in the state. Dall's porpoise have been observed in lower Cook Inlet, including Kachemak Bay and near Anchor Point (Owl Ridge 2014), but sightings there are rare. The concentration of sightings of Dall's porpoise in a southerly part of the Inlet suggest it is unlikely they will be encountered during EMALL's activities. Therefore, no take of Dall's porpoise is authorized.

Steller Sea Lion (Eumetopias jubatus)

The Western Stock of the Steller sea lion is defined as all populations west of longitude 144° W. to the western end of the Aleutian Islands. The most recent estimate for this stock is 45,649 animals (Allen and Angliss 2014), considerably less than that estimated 140,000 animals in the 1950s (Merrick et al. 1987). Because of this dramatic decline, the stock was listed under the ESA as a threatened DPS in 1990, and relisted as endangered in 1997. Critical habitat was designated in 1993, and is defined as a 20-nautical-mile radius around all major rookeries and haulout sites. The 20-nautical-mile buffer was established based on telemetry data that indicated these sea lions concentrated their summer foraging effort within this distance of rookeries and haul outs.

Steller sea lions inhabit lower Cook Inlet, especially in the vicinity of Shaw Island and Elizabeth Island (Nagahut Rocks) haulout sites (Rugh et al. 2005a), but are rarely seen in upper Cook Inlet (Nemeth et al. 2007). Of the 42 Steller sea lion groups recorded during Cook Inlet aerial surveys between 1993 and 2004, none were recorded north of Anchor Point and only one in the vicinity of Kachemak Bay (Rugh et al. 2005a). Marine mammal observers associated with Buccaneer's drilling project off Cape Starichkof did observe seven Steller sea lions during the summer of 2013 (Owl Ridge 2014).

The upper reaches of Cook Inlet may not provide adequate foraging conditions for sea lions for establishing a major haul out presence. Steller sea lions feed largely on walleye pollock, salmon and arrowtooth flounder during the summer, and walleye pollock and Pacific cod during the winter (Sinclair and Zeppelin 2002), none of which, except for salmon, are found in abundance in upper Cook Inlet (Nemeth et al. 2007). Steller sea lions are unlikely to be encountered during operations in upper Cook Inlet, as they are primarily encountered along the Kenai Peninsula, especially closer to Anchor Point. Therefore, no take of Steller sea lion is authorized.

Potential Effects of the Specified Activity on Marine Mammals and Their Habitat

This section includes a summary and discussion of the ways that components (seismic airgun operations, sub-bottom profiler chirper and boomer, vibracore) of the specified activity may impact marine mammals. The “Estimated Take by Incidental Harassment” section later in this document will include a quantitative analysis of the number of individuals that NMFS expects to be taken by this activity. The “Negligible Impact Analysis” section will include the analysis of how this specific proposed activity would impact marine mammals and will consider the content of this section, the “Estimated Take by Incidental Harassment” section, the “Mitigation” section, and the “Anticipated Effects on Marine Mammal Habitat” section to draw conclusions regarding the likely impacts of this activity on the reproductive success or survivorship of individuals and from that on the affected marine mammal populations or stocks.

NMFS intends to provide a background of potential effects of EMALL's activities in this section. Operating active acoustic sources have the potential for adverse effects on marine mammals. The majority of anticipated impacts would be from the use of active acoustic sources.

Acoustic Impacts

When considering the influence of various kinds of sound on the marine environment, it is necessary to understand that different kinds of marine life are sensitive to different frequencies of sound. Current data indicate that not all marine mammal species have equal hearing capabilities (Richardson et al., 1995; Southall et al., 1997; Wartzok and Ketten, 1999; Au and Hastings, 2008).

Southall et al. (2007) designated “functional hearing groups” for marine mammals based on available behavioral data; audiograms derived from auditory evoked potentials; anatomical modeling; and other data. Southall et al. (2007) also estimated the lower and upper frequencies of functional hearing for each group. However, animals are less sensitive to sounds at the outer edges of their functional hearing range and are more sensitive to a range of frequencies within the middle of their functional hearing range.

The functional groups and the associated frequencies are:

• Low frequency cetaceans (13 species of mysticetes): Functional hearing estimates occur between approximately 7 Hertz (Hz) and 25 kHz (extended from 22 kHz based on data indicating that some mysticetes can hear above 22 kHz; Au et al., 2006; Lucifredi and Stein, 2007; Ketten and Mountain, 2009; Tubelli et al., 2012);
• Mid-frequency cetaceans (32 species of dolphins, six species of larger toothed whales, and 19 species of beaked and bottlenose whales): Functional hearing estimates occur between approximately 150 Hz and 160 kHz;
• High-frequency cetaceans (eight species of true porpoises, six species of river dolphins, Kogia, the franciscana, and four species of cephalorhynchids): Functional hearing estimates occur between approximately 200 Hz and 180 kHz; and
• Pinnipeds in water: Phocid (true seals) functional hearing estimates occur between approximately 75 Hz and 100 kHz (Hemila et al., 2006; Mulsow et al., 2011; Reichmuth et al., 2013) and otariid (seals and sea lions) functional hearing estimates occur between approximately 100 Hz to 40 kHz.

As mentioned previously in this document, Cook Inlet beluga whales, harbor porpoise, killer whales, and harbor seals (3 odontocetes and 1 phocid) would likely occur in the action area. Table 2 presents the classification of these species into their respective functional hearing group. NMFS consider a species' functional hearing group when analyzing the effects of exposure to sound on marine mammals.

Table 2—Classification of Marine Mammals That Could Potentially Occur in the Proposed Activity Area in Cook Inlet, 2015 by Functional Hearing Group

[Southall et al., 2007]

Mid-Frequency Hearing Range	Beluga whale, killer whale.
High Frequency Hearing Range	Harbor porpoise.
Pinnipeds in Water Hearing Range	Harbor seal.

1. Potential Effects of Airgun Sounds on Marine Mammals

The effects of sounds from airgun operations might include one or more of the following: Tolerance, masking of natural sounds, behavioral disturbance, temporary or permanent impairment, or non-auditory physical or physiological effects (Richardson et al., 1995; Gordon et al., 2003; Nowacek et al., 2007; Southall et al., 2007). The effects of noise on marine mammals are highly variable, often depending on species and contextual factors (based on Richardson et al., 1995).

Tolerance

Studies on marine mammals' tolerance to sound in the natural environment are relatively rare. Richardson et al. (1995) defined tolerance as the occurrence of marine mammals in areas where they are exposed to human activities or manmade noise. In many cases, tolerance develops by the animal habituating to the stimulus (i.e., the gradual waning of responses to a repeated or ongoing stimulus) (Richardson, et al., 1995), but because of ecological or physiological requirements, many marine animals may need to remain in areas where they are exposed to chronic stimuli (Richardson, et al., 1995).

Numerous studies have shown that pulsed sounds from airguns are often readily detectable in the water at distances of many kilometers. Several studies have also shown that marine mammals at distances of more than a few kilometers from operating seismic vessels often show no apparent response. That is often true even in cases when the pulsed sounds must be readily audible to the animals based on measured received levels and the hearing sensitivity of the marine mammal group. Although various baleen whales and toothed whales, and (less frequently) pinnipeds have been shown to react behaviorally to airgun pulses under some conditions, at other times marine mammals of all three types have shown no overt reactions (Stone, 2003; Stone and Tasker, 2006; Moulton et al. 2005, 2006) and (MacLean and Koski, 2005; Bain and Williams, 2006).

Weir (2008) observed marine mammal responses to seismic pulses from a 24 airgun array firing a total volume of either 5,085 in³ or 3,147 in³ in Angolan waters between August 2004 and May 2005. Weir (2008) recorded a total of 207 sightings of humpback whales (n = 66), sperm whales (n = 124), and Atlantic spotted dolphins (n = 17) and reported that there were no significant differences in encounter rates (sightings per hour) for humpback and sperm whales according to the airgun array's operational status (i.e., active versus silent).

Bain and Williams (2006) examined the effects of a large airgun array (maximum total discharge volume of 1,100 in ³) on six species in shallow waters off British Columbia and Washington: Harbor seal, California sea lion, Steller sea lion, gray whale, Dall's porpoise, and harbor porpoise. Harbor porpoises showed reactions at received levels less than 155 dB re: 1 μPa at a distance of greater than 70 km (43 mi) from the seismic source (Bain and Williams, 2006). However, the tendency for greater responsiveness by harbor porpoise is consistent with their relative responsiveness to boat traffic and some other acoustic sources (Richardson, et al., 1995; Southall, et al., 2007). In contrast, the authors reported that gray whales seemed to tolerate exposures to sound up to approximately 170 dB re: 1 μPa (Bain and Williams, 2006) and Dall's porpoises occupied and tolerated areas receiving exposures of 170-180 dB re: 1 μPa (Bain and Williams, 2006; Parsons, et al., 2009). The authors observed several gray whales that moved away from the airguns toward deeper water where sound levels were higher due to propagation effects resulting in higher noise exposures (Bain and Williams, 2006). However, it is unclear whether their movements reflected a response to the sounds (Bain and Williams, 2006). Thus, the authors surmised that the lack of gray whale responses to higher received sound levels were ambiguous at best because one expects the species to be the most sensitive to the low-frequency sound emanating from the airguns (Bain and Williams, 2006).

Pirotta et al., (2014) observed short-term responses of harbor porpoises to a two-dimensional (2-D) seismic survey in an enclosed bay in northeast Scotland which did not result in broad-scale displacement. The harbor porpoises that remained in the enclosed bay area reduced their buzzing activity by 15 percent during the seismic survey (Pirotta, et al., 2014). Thus, the authors suggest that animals exposed to anthropogenic disturbance may make trade-offs between perceived risks and the cost of leaving disturbed areas (Pirotta, et al., 2014).

Masking

Marine mammals use acoustic signals for a variety of purposes, which differ among species, but include communication between individuals, navigation, foraging, reproduction, avoiding predators, and learning about their environment (Erbe and Farmer, 2000; Tyack, 2000).

The term masking refers to the inability of an animal to recognize the occurrence of an acoustic stimulus because of interference of another acoustic stimulus (Clark et al., 2009). Thus, masking is the obscuring of sounds of interest by other sounds, often at similar frequencies. It is a phenomenon that affects animals that are trying to receive acoustic information about their environment, including sounds from other members of their species, predators, prey, and sounds that allow them to orient in their environment. Masking these acoustic signals can disturb the behavior of individual animals, groups of animals, or entire populations in certain circumstances.

Introduced underwater sound may, through masking, reduce the effective communication distance of a marine mammal species if the frequency of the source is close to that used as a signal by the marine mammal, and if the anthropogenic sound is present for a significant fraction of the time (Richardson et al., 1995).

Marine mammals are thought to be able to compensate for masking by adjusting their acoustic behavior through shifting call frequencies, increasing call volume, and increasing vocalization rates. For example in one study, blue whales increased call rates when exposed to noise from seismic surveys in the St. Lawrence Estuary (Di Iorio and Clark, 2010). Other studies reported that some North Atlantic right whales exposed to high shipping noise increased call frequency (Parks et al., 2007) and some humpback whales responded to low-frequency active sonar playbacks by increasing song length (Miller et al., 2000). Additionally, beluga whales change their vocalizations in the presence of high background noise possibly to avoid masking calls (Au et al., 1985; Lesage et al., 1999; Scheifele et al., 2005).

Studies have shown that some baleen and toothed whales continue calling in the presence of seismic pulses, and some researchers have heard these calls between the seismic pulses (e.g., McDonald et al., 1995; Greene et al., 1999; Nieukirk et al., 2004; Smultea et al., 2004; Holst et al., 2005a, 2005b, 2006; and Dunn and Hernandez, 2009).

In contrast, Clark and Gagnon (2006) reported that fin whales in the northeast Pacific Ocean went silent for an extended period starting soon after the onset of a seismic survey in the area. Similarly, NMFS is aware of one report that observed sperm whales ceased calls when exposed to pulses from a very distant seismic ship (Bowles et al., 1994). However, more recent studies have found that sperm whales continued calling in the presence of seismic pulses (Madsen et al., 2002; Tyack et al., 2003; Smultea et al., 2004; Holst et al., 2006; and Jochens et al., 2008).

Risch et al., (2012) documented reductions in humpback whale vocalizations in the Stellwagen Bank National Marine Sanctuary concurrent with transmissions of the Ocean Acoustic Waveguide Remote Sensing (OAWRS) low-frequency fish sensor system at distances of 200 km (124 mi) from the source. The recorded OAWRS produced series of frequency modulated pulses and the signal received levels ranged from 88 to 110 dB re: 1 μPa (Risch, et al., 2012). The authors hypothesized that individuals did not leave the area but instead ceased singing and noted that the duration and frequency range of the OAWRS signals (a novel sound to the whales) were similar to those of natural humpback whale song components used during mating (Risch et al., 2012). Thus, the novelty of the sound to humpback whales in the study area provided a compelling contextual probability for the observed effects (Risch et al., 2012). However, the authors did not state or imply that these changes had long-term effects on individual animals or populations (Risch et al., 2012).

Several studies have also reported hearing dolphins and porpoises calling while airguns were operating (e.g., Gordon et al., 2004; Smultea et al., 2004; Holst et al., 2005a, b; and Potter et al., 2007). The sounds important to small odontocetes are predominantly at much higher frequencies than the dominant components of airgun sounds, thus limiting the potential for masking in those species.

Although some degree of masking is inevitable when high levels of manmade broadband sounds are present in the sea, marine mammals have evolved systems and behavior that function to reduce the impacts of masking. Odontocete conspecifics may readily detect structured signals, such as the echolocation click sequences of small toothed whales even in the presence of strong background noise because their frequency content and temporal features usually differ strongly from those of the background noise (Au and Moore, 1988, 1990). The components of background noise that are similar in frequency to the sound signal in question primarily determine the degree of masking of that signal.

Redundancy and context can also facilitate detection of weak signals. These phenomena may help marine mammals detect weak sounds in the presence of natural or manmade noise. Most masking studies in marine mammals present the test signal and the masking noise from the same direction. The sound localization abilities of marine mammals suggest that, if signal and noise come from different directions, masking would not be as severe as the usual types of masking studies might suggest (Richardson et al., 1995). The dominant background noise may be highly directional if it comes from a particular anthropogenic source such as a ship or industrial site. Directional hearing may significantly reduce the masking effects of these sounds by improving the effective signal-to-noise ratio. In the cases of higher frequency hearing by the bottlenose dolphin, beluga whale, and killer whale, empirical evidence confirms that masking depends strongly on the relative directions of arrival of sound signals and the masking noise (Penner et al., 1986; Dubrovskiy, 1990; Bain et al., 1993; Bain and Dahlheim, 1994). Toothed whales and probably other marine mammals as well, have additional capabilities besides directional hearing that can facilitate detection of sounds in the presence of background noise. There is evidence that some toothed whales can shift the dominant frequencies of their echolocation signals from a frequency range with a lot of ambient noise toward frequencies with less noise (Au et al., 1974, 1985; Moore and Pawloski, 1990; Thomas and Turl, 1990; Romanenko and Kitain, 1992; Lesage et al., 1999). A few marine mammal species increase the source levels or alter the frequency of their calls in the presence of elevated sound levels (Dahlheim, 1987; Au, 1993; Lesage et al., 1993, 1999; Terhune, 1999; Foote et al., 2004; Parks et al., 2007, 2009; Di Iorio and Clark, 2010; Holt et al., 2009).

These data demonstrating adaptations for reduced masking pertain mainly to the very high frequency echolocation signals of toothed whales. There is less information about the existence of corresponding mechanisms at moderate or low frequencies or in other types of marine mammals. For example, Zaitseva et al. (1980) found that, for the bottlenose dolphin, the angular separation between a sound source and a masking noise source had little effect on the degree of masking when the sound frequency was 18 kHz, in contrast to the pronounced effect at higher frequencies. Studies have noted directional hearing at frequencies as low as 0.5-2 kHz in several marine mammals, including killer whales (Richardson et al., 1995a). This ability may be useful in reducing masking at these frequencies. In summary, high levels of sound generated by anthropogenic activities may act to mask the detection of weaker biologically important sounds by some marine mammals. This masking may be more prominent for lower frequencies. For higher frequencies, such as that used in echolocation by toothed whales, several mechanisms are available that may allow them to reduce the effects of such masking.

Behavioral Disturbance

Marine mammals may behaviorally react to sound when exposed to anthropogenic noise. Reactions to sound, if any, depend on species, state of maturity, experience, current activity, reproductive state, time of day, and many other factors (Richardson et al., 1995; D'Spain & Wartzok, 2004; Southall et al., 2007; Weilgart, 2007).

Types of behavioral reactions can include the following: changing durations of surfacing and dives, number of blows per surfacing, or moving direction and/or speed; reduced/increased vocal activities; changing/cessation of certain behavioral activities (such as socializing or feeding); visible startle response or aggressive behavior (such as tail/fluke slapping or jaw clapping); avoidance of areas where noise sources are located; and/or flight responses (e.g., pinnipeds flushing into water from haulouts or rookeries).

The biological significance of many of these behavioral disturbances is difficult to predict, especially if the detected disturbances appear minor. However, one could expect the consequences of behavioral modification to be biologically significant if the change affects growth, survival, and/or reproduction (e.g., Lusseau and Bejder, 2007; Weilgart, 2007). Examples of behavioral modifications that could impact growth, survival, or reproduction include:

• Drastic changes in diving/surfacing patterns (such as those associated with beaked whale stranding related to exposure to military mid-frequency tactical sonar);
• Permanent habitat abandonment due to loss of desirable acoustic environment; and
• Disruption of feeding or social interaction resulting in significant energetic costs, inhibited breeding, or cow-calf separation.

The onset of behavioral disturbance from anthropogenic noise depends on both external factors (characteristics of noise sources and their paths) and the receiving animals (hearing, motivation, experience, demography) and is also difficult to predict (Richardson et al., 1995; Southall et al., 2007). Many studies have also shown that marine mammals at distances more than a few kilometers away often show no apparent response when exposed to seismic activities (e.g., Madsen & Mohl, 2000 for sperm whales; Malme et al., 1983, 1984 for gray whales; and Richardson et al., 1986 for bowhead whales). Other studies have shown that marine mammals continue important behaviors in the presence of seismic pulses (e.g., Dunn & Hernandez, 2009 for blue whales; Greene Jr. et al., 1999 for bowhead whales; Holst and Beland, 2010; Holst and Smultea, 2008; Holst et al., 2005; Nieukirk et al., 2004; Richardson, et al., 1986; Smultea et al., 2004).

Baleen Whales: Studies have shown that underwater sounds from seismic activities are often readily detectable by baleen whales in the water at distances of many kilometers (Castellote et al., 2012 for fin whales).

Observers have seen various species of Balaenoptera (blue, sei, fin, and minke whales) in areas ensonified by airgun pulses (Stone, 2003; MacLean and Haley, 2004; Stone and Tasker, 2006), and have localized calls from blue and fin whales in areas with airgun operations (e.g., McDonald et al., 1995; Dunn and Hernandez, 2009; Castellote et al., 2010). Sightings by observers on seismic vessels off the United Kingdom from 1997 to 2000 suggest that, during times of good visibility, sighting rates for mysticetes (mainly fin and sei whales) were similar when large arrays of airguns were shooting versus silent (Stone, 2003; Stone and Tasker, 2006). However, these whales tended to exhibit localized avoidance, remaining significantly further (on average) from the airgun array during seismic operations compared with non-seismic periods (Stone and Tasker, 2006).

Ship-based monitoring studies of baleen whales (including blue, fin, sei, minke, and humpback whales) in the northwest Atlantic found that overall, this group had lower sighting rates during seismic versus non-seismic periods (Moulton and Holst, 2010). The authors observed that baleen whales as a group were significantly farther from the vessel during seismic compared with non-seismic periods. Moreover, the authors observed that the whales swam away more often from the operating seismic vessel (Moulton and Holst, 2010). Initial sightings of blue and minke whales were significantly farther from the vessel during seismic operations compared to non-seismic periods and the authors observed the same trend for fin whales (Moulton and Holst, 2010). Also, the authors observed that minke whales most often swam away from the vessel when seismic operations were underway (Moulton and Holst, 2010).

Toothed Whales: Few systematic data are available describing reactions of toothed whales to noise pulses. However, systematic work on sperm whales is underway (e.g., Gordon et al., 2006; Madsen et al., 2006; Winsor and Mate, 2006; Jochens et al., 2008; Miller et al., 2009) and there is an increasing amount of information about responses of various odontocetes, including killer whales and belugas, to seismic surveys based on monitoring studies (e.g., Stone, 2003; Smultea et al., 2004; Moulton and Miller, 2005; Bain and Williams, 2006; Holst et al., 2006; Stone and Tasker, 2006; Potter et al., 2007; Hauser et al., 2008; Holst and Smultea, 2008; Weir, 2008; Barkaszi et al., 2009; Richardson et al., 2009; Moulton and Holst, 2010). Reactions of toothed whales to large arrays of airguns are variable and, at least for delphinids, seem to be confined to a smaller radius than has been observed for mysticetes.

Observers stationed on seismic vessels operating off the United Kingdom from 1997-2000 have provided data on the occurrence and behavior of various toothed whales exposed to seismic pulses (Stone, 2003; Gordon et al., 2004). The studies note that killer whales were significantly farther from large airgun arrays during periods of active airgun operations compared with periods of silence. The displacement of the median distance from the array was approximately 0.5 km (0.3 mi) or more. Killer whales also appear to be more tolerant of seismic shooting in deeper water (Stone, 2003; Gordon et al., 2004).

The beluga may be a species that (at least in certain geographic areas) shows long-distance avoidance of seismic vessels. Aerial surveys during seismic operations in the southeastern Beaufort Sea recorded much lower sighting rates of beluga whales within 10-20 km (6.2-12.4 mi) of an active seismic vessel. These results were consistent with the low number of beluga sightings reported by observers aboard the seismic vessel, suggesting that some belugas might have been avoiding the seismic operations at distances of 10-20 km (6.2-12.4 mi) (Miller et al., 2005).

Delphinids

Seismic operators and protected species observers (observers) on seismic vessels regularly see dolphins and other small toothed whales near operating airgun arrays, but in general there is a tendency for most delphinids to show some avoidance of operating seismic vessels (e.g., Goold, 1996a,b,c; Calambokidis and Osmek, 1998; Stone, 2003; Moulton and Miller, 2005; Holst et al., 2006; Stone and Tasker, 2006; Weir, 2008; Richardson et al., 2009; Barkaszi et al., 2009; Moulton and Holst, 2010). Some dolphins seem to be attracted to the seismic vessel and floats, and some ride the bow wave of the seismic vessel even when large arrays of airguns are firing (e.g., Moulton and Miller, 2005). Nonetheless, there have been indications that small toothed whales sometimes move away or maintain a somewhat greater distance from the vessel when a large array of airguns is operating than when it is silent (e.g., Goold, 1996a,b,c; Stone and Tasker, 2006; Weir, 2008; Moulton and Holst, 2010). In most cases, the avoidance radii for delphinids appear to be small, on the order of one km or less, and some individuals show no apparent avoidance.

Captive bottlenose dolphins exhibited changes in behavior when exposed to strong pulsed sounds similar in duration to those typically used in seismic surveys (Finneran et al., 2000, 2002, 2005). However, the animals tolerated high received levels of sound (pk-pk level >200 dB re 1 μPa) before exhibiting aversive behaviors.

Porpoises

Results for porpoises depend upon the species. The limited available data suggest that harbor porpoises show stronger avoidance of seismic operations than do Dall's porpoises (Stone, 2003; MacLean and Koski, 2005; Bain and Williams, 2006; Stone and Tasker, 2006). Dall's porpoises seem relatively tolerant of airgun operations (MacLean and Koski, 2005; Bain and Williams, 2006), although they too have been observed to avoid large arrays of operating airguns (Calambokidis and Osmek, 1998; Bain and Williams, 2006). This apparent difference in responsiveness of these two porpoise species is consistent with their relative responsiveness to boat traffic and some other acoustic sources (Richardson et al., 1995; Southall et al., 2007).

Pinnipeds

Pinnipeds are not likely to show a strong avoidance reaction to the airgun sources proposed for use. Visual monitoring from seismic vessels has shown only slight (if any) avoidance of airguns by pinnipeds and only slight (if any) changes in behavior. Monitoring work in the Alaskan Beaufort Sea during 1996-2001 provided considerable information regarding the behavior of Arctic ice seals exposed to seismic pulses (Harris et al., 2001; Moulton and Lawson, 2002). These seismic projects usually involved arrays of 6 to 16 airguns with total volumes of 560 to 1,500 in ³. The combined results suggest that some seals avoid the immediate area around seismic vessels. In most survey years, ringed seal (Phoca hispida) sightings tended to be farther away from the seismic vessel when the airguns were operating than when they were not (Moulton and Lawson, 2002). However, these avoidance movements were relatively small, on the order of 100 m (328 ft) to a few hundreds of meters, and many seals remained within 100-200 m (328-656 ft) of the trackline as the operating airgun array passed by the animals. Seal sighting rates at the water surface were lower during airgun array operations than during no-airgun periods in each survey year except 1997. Similarly, seals are often very tolerant of pulsed sounds from seal-scaring devices (Mate and Harvey, 1987; Jefferson and Curry, 1994; Richardson et al., 1995). However, initial telemetry work suggests that avoidance and other behavioral reactions by two other species of seals to small airgun sources may at times be stronger than evident to date from visual studies of pinniped reactions to airguns (Thompson et al., 1998).

Hearing Impairment

Exposure to high intensity sound for a sufficient duration may result in auditory effects such as a noise-induced threshold shift—an increase in the auditory threshold after exposure to noise (Finneran et al., 2005). Factors that influence the amount of threshold shift include the amplitude, duration, frequency content, temporal pattern, and energy distribution of noise exposure. The magnitude of hearing threshold shift normally decreases over time following cessation of the noise exposure. The amount of threshold shift just after exposure is the initial threshold shift. If the threshold shift eventually returns to zero (i.e., the threshold returns to the pre-exposure value), it is a temporary threshold shift (Southall et al., 2007).

Threshold Shift (noise-induced loss of hearing)—When animals exhibit reduced hearing sensitivity (i.e., sounds must be louder for an animal to detect them) following exposure to an intense sound or sound for long duration, it is referred to as a noise-induced threshold shift (TS). An animal can experience temporary threshold shift (TTS) or permanent threshold shift (PTS). TTS can last from minutes or hours to days (i.e., there is complete recovery), can occur in specific frequency ranges (i.e., an animal might only have a temporary loss of hearing sensitivity between the frequencies of 1 and 10 kHz), and can be of varying amounts (for example, an animal's hearing sensitivity might be reduced initially by only 6 dB or reduced by 30 dB). PTS is permanent, but some recovery is possible. PTS can also occur in a specific frequency range and amount as mentioned above for TTS.

The following physiological mechanisms are thought to play a role in inducing auditory TS: Effects to sensory hair cells in the inner ear that reduce their sensitivity, modification of the chemical environment within the sensory cells, residual muscular activity in the middle ear, displacement of certain inner ear membranes, increased blood flow, and post-stimulatory reduction in both efferent and sensory neural output (Southall et al., 2007). The amplitude, duration, frequency, temporal pattern, and energy distribution of sound exposure all can affect the amount of associated TS and the frequency range in which it occurs. As amplitude and duration of sound exposure increase, so, generally, does the amount of TS, along with the recovery time. For intermittent sounds, less TS could occur than compared to a continuous exposure with the same energy (some recovery could occur between intermittent exposures depending on the duty cycle between sounds) (Kryter et al., 1966; Ward, 1997). For example, one short but loud (higher SPL) sound exposure may induce the same impairment as one longer but softer sound, which in turn may cause more impairment than a series of several intermittent softer sounds with the same total energy (Ward, 1997). Additionally, though TTS is temporary, prolonged exposure to sounds strong enough to elicit TTS, or shorter-term exposure to sound levels well above the TTS threshold, can cause PTS, at least in terrestrial mammals (Kryter, 1985). Although in the case of EMALL'ssurvey, NMFS does not expect that animals would experience levels high enough or durations long enough to result in PTS given that the airgun is a very low volume airgun, and the use of the airgun will be restricted to seven days in a small geographic area.

PTS is considered auditory injury (Southall et al., 2007). Irreparable damage to the inner or outer cochlear hair cells may cause PTS; however, other mechanisms are also involved, such as exceeding the elastic limits of certain tissues and membranes in the middle and inner ears and resultant changes in the chemical composition of the inner ear fluids (Southall et al., 2007).

Although the published body of scientific literature contains numerous theoretical studies and discussion papers on hearing impairments that can occur with exposure to a loud sound, only a few studies provide empirical information on the levels at which noise-induced loss in hearing sensitivity occurs in non-human animals.

Recent studies by Kujawa and Liberman (2009) and Lin et al. (2011) found that despite completely reversible threshold shifts that leave cochlear sensory cells intact, large threshold shifts could cause synaptic level changes and delayed cochlear nerve degeneration in mice and guinea pigs, respectively. NMFS notes that the high level of TTS that led to the synaptic changes shown in these studies is in the range of the high degree of TTS that Southall et al. (2007) used to calculate PTS levels. It is unknown whether smaller levels of TTS would lead to similar changes. NMFS, however, acknowledges the complexity of noise exposure on the nervous system, and will re-examine this issue as more data become available.

For marine mammals, published data are limited to the captive bottlenose dolphin, beluga, harbor porpoise, and Yangtze finless porpoise (Finneran et al., 2000, 2002, 2003, 2005, 2007, 2010a, 2010b; Finneran and Schlundt, 2010; Lucke et al., 2009; Mooney et al., 2009a, 2009b; Popov et al., 2011a, 2011b; Kastelein et al., 2012a; Schlundt et al., 2000; Nachtigall et al., 2003, 2004). For pinnipeds in water, data are limited to measurements of TTS in harbor seals, an elephant seal, and California sea lions (Kastak et al., 1999, 2005; Kastelein et al., 2012b).

Lucke et al. (2009) found a threshold shift (TS) of a harbor porpoise after exposing it to airgun noise with a received sound pressure level (SPL) at 200.2 dB (peak-to-peak) re: 1 μPa, which corresponds to a sound exposure level of 164.5 dB re: 1 μPa2 s after integrating exposure. NMFS currently uses the root-mean-square (rms) of received SPL at 180 dB and 190 dB re: 1 μPa as the threshold above which permanent threshold shift (PTS) could occur for cetaceans and pinnipeds, respectively. Because the airgun noise is a broadband impulse, one cannot directly determine the equivalent of rms SPL from the reported peak-to-peak SPLs. However, applying a conservative conversion factor of 16 dB for broadband signals from seismic surveys (McCauley, et al., 2000) to correct for the difference between peak-to-peak levels reported in Lucke et al. (2009) and rms SPLs, the rms SPL for TTS would be approximately 184 dB re: 1 μPa, and the received levels associated with PTS (Level A harassment) would be higher. This is still above NMFS' current 180 dB rms re: 1 μPa threshold for injury. However, NMFS recognizes that TTS of harbor porpoises is lower than other cetacean species empirically tested (Finneran & Schlundt, 2010; Finneran et al., 2002; Kastelein and Jennings, 2012).

A recent study on bottlenose dolphins (Schlundt, et al., 2013) measured hearing thresholds at multiple frequencies to determine the amount of TTS induced before and after exposure to a sequence of impulses produced by a seismic air gun. The air gun volume and operating pressure varied from 40-150 in³ and 1000-2000 psi, respectively. After three years and 180 sessions, the authors observed no significant TTS at any test frequency, for any combinations of air gun volume, pressure, or proximity to the dolphin during behavioral tests (Schlundt, et al., 2013). Schlundt et al. (2013) suggest that the potential for airguns to cause hearing loss in dolphins is lower than previously predicted, perhaps as a result of the low-frequency content of air gun impulses compared to the high-frequency hearing ability of dolphins.

Marine mammal hearing plays a critical role in communication with conspecifics, and interpretation of environmental cues for purposes such as predator avoidance and prey capture. Depending on the degree (elevation of threshold in dB), duration (i.e., recovery time), and frequency range of TTS, and the context in which it is experienced, TTS can have effects on marine mammals ranging from discountable to serious (similar to those discussed in auditory masking, below). For example, a marine mammal may be able to readily compensate for a brief, relatively small amount of TTS in a non-critical frequency range that occurs during a time where ambient noise is lower and there are not as many competing sounds present. Alternatively, a larger amount and longer duration of TTS sustained during time when communication is critical for successful mother/calf interactions could have more serious impacts. Also, depending on the degree and frequency range, the effects of PTS on an animal could range in severity, although it is considered generally more serious because it is a permanent condition. Of note, reduced hearing sensitivity as a simple function of aging has been observed in marine mammals, as well as humans and other taxa (Southall et al., 2007), so one can infer that strategies exist for coping with this condition to some degree, though likely not without cost.

Given the higher level of sound necessary to cause PTS as compared with TTS, it is considerably less likely that PTS would occur during the survey; TTS is also unlikely. Cetaceans generally avoid the immediate area around operating seismic vessels, as do some other marine mammals. Some pinnipeds show avoidance reactions to airguns, but their avoidance reactions are generally not as strong or consistent compared to cetacean reactions.

Non-auditory Physical Effects: Non-auditory physical effects might occur in marine mammals exposed to strong underwater pulsed sound. Possible types of non-auditory physiological effects or injuries that theoretically might occur in mammals close to a strong sound source include stress, neurological effects, bubble formation, and other types of organ or tissue damage. Some marine mammal species (i.e., beaked whales) may be especially susceptible to injury and/or stranding when exposed to strong pulsed sounds.

Classic stress responses begin when an animal's central nervous system perceives a potential threat to its homeostasis. That perception triggers stress responses regardless of whether a stimulus actually threatens the animal; the mere perception of a threat is sufficient to trigger a stress response (Moberg, 2000; Sapolsky et al., 2005; Seyle, 1950). Once an animal's central nervous system perceives a threat, it mounts a biological response or defense that consists of a combination of the four general biological defense responses: Behavioral responses; autonomic nervous system responses; neuroendocrine responses; or immune responses.

In the case of many stressors, an animal's first and most economical (in terms of biotic costs) response is behavioral avoidance of the potential stressor or avoidance of continued exposure to a stressor. An animal's second line of defense to stressors involves the sympathetic part of the autonomic nervous system and the classical “fight or flight” response, which includes the cardiovascular system, the gastrointestinal system, the exocrine glands, and the adrenal medulla to produce changes in heart rate, blood pressure, and gastrointestinal activity that humans commonly associate with stress. These responses have a relatively short duration and may or may not have significant long-term effects on an animal's welfare.

An animal's third line of defense to stressors involves its neuroendocrine or sympathetic nervous systems; the system that has received the most study has been the hypothalmus-pituitary-adrenal (HPA) system (also known as the HPA axis in mammals or the hypothalamus-pituitary-interrenal axis in fish and some reptiles). Unlike stress responses associated with the autonomic nervous system, the pituitary hormones regulate virtually all neuroendocrine functions affected by stress—including immune competence, reproduction, metabolism, and behavior. Stress-induced changes in the secretion of pituitary hormones have been implicated in failed reproduction (Moberg, 1987; Rivier, 1995), altered metabolism (Elasser et al., 2000), reduced immune competence (Blecha, 2000), and behavioral disturbance. Increases in the circulation of glucocorticosteroids (cortisol, corticosterone, and aldosterone in marine mammals; see Romano et al., 2004) have been equated with stress for many years.

The primary distinction between stress (which is adaptive and does not normally place an animal at risk) and distress is the biotic cost of the response. During a stress response, an animal uses glycogen stores that the body quickly replenishes after alleviation of the stressor. In such circumstances, the cost of the stress response would not pose a risk to the animal's welfare. However, when an animal does not have sufficient energy reserves to satisfy the energetic costs of a stress response, it diverts energy resources from other biotic functions, which impair those functions that experience the diversion. For example, when mounting a stress response diverts energy away from growth in young animals, those animals may experience stunted growth (McEwen and Wingfield, 2003). When mounting a stress response diverts energy from a fetus, an animal's reproductive success and fitness will suffer. In these cases, the animals will have entered a pre-pathological or pathological state called “distress” (sensu Seyle, 1950) or “allostatic loading” (sensu McEwen and Wingfield, 2003). This pathological state will last until the animal replenishes its biotic reserves sufficient to restore normal function. Note that these examples involved a long-term (days or weeks) stress response exposure to stimuli.

Relationships between these physiological mechanisms, animal behavior, and the costs of stress responses have also been documented fairly well through controlled experiment; because this physiology exists in every vertebrate that has been studied, it is not surprising that stress responses and their costs have been documented in both laboratory and free-living animals (for examples see, Holberton et al., 1996; Hood et al., 1998; Jessop et al., 2003; Krausman et al., 2004; Lankford et al., 2005; Reneerkens et al., 2002; Thompson and Hamer, 2000). Although no information has been collected on the physiological responses of marine mammals to anthropogenic sound exposure, studies of other marine animals and terrestrial animals would lead us to expect some marine mammals to experience physiological stress responses and, perhaps, physiological responses that would be classified as “distress” upon exposure to anthropogenic sounds.

For example, Jansen (1998) reported on the relationship between acoustic exposures and physiological responses that are indicative of stress responses in humans (e.g., elevated respiration and increased heart rates). Jones (1998) reported on reductions in human performance when faced with acute, repetitive exposures to acoustic disturbance. Trimper et al. (1998) reported on the physiological stress responses of osprey to low-level aircraft noise while Krausman et al. (2004) reported on the auditory and physiology stress responses of endangered Sonoran pronghorn to military overflights. Smith et al. (2004a, 2004b) identified noise-induced physiological transient stress responses in hearing-specialist fish (i.e., goldfish) that accompanied short- and long-term hearing losses. Welch and Welch (1970) reported physiological and behavioral stress responses that accompanied damage to the inner ears of fish and several mammals.

Hearing is one of the primary senses marine mammals use to gather information about their environment and communicate with conspecifics. Although empirical information on the relationship between sensory impairment (TTS, PTS, and acoustic masking) on marine mammals remains limited, we assume that reducing a marine mammal's ability to gather information about its environment and communicate with other members of its species would induce stress, based on data that terrestrial animals exhibit those responses under similar conditions (NRC, 2003) and because marine mammals use hearing as their primary sensory mechanism. Therefore, NMFS assumes that acoustic exposures sufficient to trigger onset PTS or TTS would be accompanied by physiological stress responses. More importantly, marine mammals might experience stress responses at received levels lower than those necessary to trigger onset TTS. Based on empirical studies of the time required to recover from stress responses (Moberg, 2000), NMFS also assumes that stress responses could persist beyond the time interval required for animals to recover from TTS and might result in pathological and pre-pathological states that would be as significant as behavioral responses to TTS.

Resonance effects (Gentry, 2002) and direct noise-induced bubble formations (Crum et al., 2005) are implausible in the case of exposure to an impulsive broadband source like an airgun array. If seismic surveys disrupt diving patterns of deep-diving species, this might result in bubble formation and a form of the bends, as speculated to occur in beaked whales exposed to sonar. However, there is no specific evidence of this upon exposure to airgun pulses.

In general, there are few data about the potential for strong, anthropogenic underwater sounds to cause non-auditory physical effects in marine mammals. Such effects, if they occur at all, would presumably be limited to short distances and to activities that extend over a prolonged period. The available data do not allow identification of a specific exposure level above which non-auditory effects can be expected (Southall et al., 2007) or any meaningful quantitative predictions of the numbers (if any) of marine mammals that might be affected in those ways. There is no definitive evidence that any of these effects occur even for marine mammals in close proximity to large arrays of airguns. In addition, marine mammals that show behavioral avoidance of seismic vessels, including some pinnipeds, are unlikely to incur non-auditory impairment or other physical effects. The low volume of the airgun proposed for this activity combined with the limited scope of use makes non-auditory physical effects from airgun use, including stress, unlikely. Therefore, we do not anticipate such effects would occur given the brief duration of exposure during the survey.

Stranding and Mortality

When a living or dead marine mammal swims or floats onto shore and becomes “beached” or incapable of returning to sea, the event is a “stranding” (Geraci et al., 1999; Perrin and Geraci, 2002; Geraci and Lounsbury, 2005; NMFS, 2007). The legal definition for a stranding under the MMPA is that “(A) a marine mammal is dead and is (i) on a beach or shore of the United States; or (ii) in waters under the jurisdiction of the United States (including any navigable waters); or (B) a marine mammal is alive and is (i) on a beach or shore of the United States and is unable to return to the water; (ii) on a beach or shore of the United States and, although able to return to the water, is in need of apparent medical attention; or (iii) in the waters under the jurisdiction of the United States (including any navigable waters), but is unable to return to its natural habitat under its own power or without assistance.”

Marine mammals strand for a variety of reasons, such as infectious agents, biotoxicosis, starvation, fishery interaction, ship strike, unusual oceanographic or weather events, sound exposure, or combinations of these stressors sustained concurrently or in series. However, the cause or causes of most strandings are unknown (Geraci et al., 1976; Eaton, 1979; Odell et al., 1980; Best, 1982). Numerous studies suggest that the physiology, behavior, habitat relationships, age, or condition of cetaceans may cause them to strand or might pre-dispose them to strand when exposed to another phenomenon. These suggestions are consistent with the conclusions of numerous other studies that have demonstrated that combinations of dissimilar stressors commonly combine to kill an animal or dramatically reduce its fitness, even though one exposure without the other does not produce the same result (Chroussos, 2000; Creel, 2005; DeVries et al., 2003; Fair and Becker, 2000; Foley et al., 2001; Moberg, 2000; Relyea, 2005a; 2005b, Romero, 2004; Sih et al., 2004). Given the low volume and source level of the proposed airgun, standing and mortality are not anticipated due to use of the airgun proposed for this activity.

2. Potential Effects of Other Acoustic Devices

Sub-Bottom Profiler

EMALL would also operate a sub-bottom profiler chirp and boomer from the source vessel during the proposed survey. The chirp's sounds are very short pulses, occurring for one ms, six times per second. Most of the energy in the sound pulses emitted by the profiler is at 2-6 kHz, and the beam is directed downward. The chirp has a maximum source level of 202 dB re: 1 µPa, with a tilt angle of 90 degrees below horizontal and a beam width of 24 degrees. The sub-bottom profiler boomer will shoot approximately every 3.125m, with shots lasting 1.5 to 2 seconds. Most of the energy in the sound pulses emitted by the boomer is concentrated between 0.5 and 6 kHz, with a source level of 205dB re: 1µPa. The tilt of the boomer is 90 degrees below horizontal, but the emission is omnidirectional. Kremser et al., (2005) noted that the probability of a cetacean swimming through the area of exposure when a bottom profiler emits a pulse is small—because if the animal was in the area, it would have to pass the transducer at close range in order to be subjected to sound levels that could cause temporary threshold shift and would likely exhibit avoidance behavior to the area near the transducer rather than swim through at such a close range.

Masking: Both the chirper and boomer sub-bottom profilers produce impulsive sound exceeding 160 dB re 1 μPa-m (rms). The louder boomer operates at a source value of 205 dB re 1 μPa-m (rms), but with a frequency between 0.5 and 6 kHz, which is lower than the maximum sensitivity hearing range of any the local species (belugas—40-130 kHz;, killer whales—7-30 kHz; harbor porpoise—100-140 kHz; and harbor seals—10-30 kHz; Wartzok and Ketten 1999, Southall et al. 2007, Kastelein et al. 2002). While the chirper is not as loud (202 dB re 1 μPa-m [rms]), it does operate at a higher frequency range (2-16 kHz), and within the maximum sensitive range of all of the local species except beluga whales.

Marine mammal communications would not likely be masked appreciably by the profiler's signals given the directionality of the signal and the brief period when an individual mammal is likely to be within its beam. Furthermore, despite the fact that the profiler overlaps with hearing ranges of many marine mammal species in the area, the profiler's signals do not overlap with the predominant frequencies in the calls, which would avoid significant masking.

Behavioral Responses: Responses to the profiler are likely to be similar to the other pulsed sources discussed earlier if received at the same levels. The behavioral response of local marine mammals to the operation of the sub-bottom profilers is expected to be similar to that of the small airgun. The odontocetes are likely to avoid the sub-bottom profiler activity, especially the naturally shy harbor porpoise, while the harbor seals might be attracted to them out of curiosity. However, because the sub-bottom profilers operate from a moving vessel, and the maximum radius to the 160 dB harassment threshold is only 263 m (863 ft), the area and time that this equipment would be affecting a given location is very small.

Hearing Impairment and Other Physical Effects: It is unlikely that the sub-bottom profilers produce sound levels strong enough to cause hearing impairment or other physical injuries even in an animal that is (briefly) in a position near the source (Wood et al., 2012). The likelihood of marine mammals moving away from the source make if further unlikely that a marine mammal would be able to approach close to the transducers.

Animals may avoid the area around the survey vessels, thereby reducing exposure. Any disturbance to marine mammals is likely to be in the form of temporary avoidance or alteration of opportunistic foraging behavior near the survey location.

Vibracore

EMALL would conduct vibracoring in a corridor across a northern portion of Cook Inlet and near the marine terminal area for a total of 55 vibracoring occurrences. While duration is dependent on sediment type, the driving mechanism, which emits sound at a source level of 187dB re: 1µPa, will only bore for 1 to 2 minutes. The sound is emitted at a frequency of 10 Hz to 20 kHz. Cores will be bored at approximately every 4 km along the pipeline corridor, for about 22 cores in that area. Approximately 33 cores will be taken in the Marine Terminal area.

Masking: It is unlikely that masking will occur due to vibracore operations. Chorney et al. (2011) conducted sound measurements on an operating vibracorer in Alaska and found that it emitted a sound pressure level at 1-m source of 188 dB re 1 μPa-m (rms), with a frequency range of between 10 Hz and 20 kHz. While the frequency range overlaps the lower ends of the maximum sensitivity hearing ranges of harbor porpoises, killer whales, and harbor seals, and the continuous sound extends 2.54 km (1.6 mi) to the 120 dB threshold, the vibracorer will operate about the one or two minutes it takes to drive the core pipe 7 m (20 ft) into the sediment, and approximately twice per day. Therefore, there is very little opportunity for this activity to mask the communication of local marine mammals.

Behavioral Response: It is unlikely that vibracoring will elicit behavioral responses from marine mammal species in the area. An analysis of similar survey activity in New Zealand classified the likely effects from vibracore and similar activity to be some habitat degradation and prey species effects, but primarily behavioral responses, although the species in the analyzed area were different to those found in Cook Inlet (Thompson, 2012).

There are no data on the behavioral response to vibracore activity of marine mammals in Cook Inlet. The closest analog to vibracoring might be exploratory drilling, although there is a notable difference in magnitude between an oil and gas drilling operation and collecting sediment samples with a vibracorer. Thomas et al. (1990) played back drilling sound to four captive beluga whales and found no statistical difference in swim patterns, social groups, respiration and dive rates, or stress hormone levels before and during playbacks. There is no reason to believe that beluga whales or any other marine mammal exposed to vibracoring sound would behave any differently, especially since vibracoring occurs for only one or two minutes.

Hearing Impairment and Other Physical Effects: The vibracorer operates for only one or two minutes at a time with a 1-m source of 187.4 dB re 1 μPa-m (rms). It is neither loud enough nor does it operate for a long enough duration to induce either TTS or PTS.

Stranding and Mortality

Stress, Stranding, and Mortality Safety zones will be established to prevent acoustical injury to local marine mammals, especially injury that could indirectly lead to mortality. Also, G&G sound is not expected to cause resonate effects to gas-filled spaces or airspaces in marine mammals based on the research of Finneran (2003) on beluga whales showing that the tissue and other body masses dampen any potential effects of resonance on ear cavities, lungs, and intestines. Chronic exposure to sound could lead to physiological stress eventually causing hormonal imbalances (NRC 2005). If survival demands are already high, and/or additional stressors are present, the ability of the animal to cope decreases, leading to pathological conditions or death (NRC 2005). Potential effects may be greatest where sound disturbance can disrupt feeding patterns including displacement from critical feeding grounds. However, all G&G exposure to marine mammals would be of duration measured in minutes.

Specific sound-related processes that lead to strandings and mortality are not well documented, but may include (1) swimming in avoidance of a sound into shallow water; (2) a change in behavior (such as a change in diving behavior) that might contribute to tissue damage, gas bubble formation, hypoxia, cardiac arrhythmia, hypertensive hemorrhage, or other forms of trauma; (3) a physiological change such as a vestibular response leading to a behavioral change or stress-induced hemorrhagic diathesis, leading in turn to tissue damage; and, (4) tissue damage directly from sound exposure, such as through acoustically mediated bubble formation and growth or acoustic resonance of tissues (Wood et al. 2012). Some of these mechanisms are unlikely to apply in the case of impulse G&G sounds, especially since airguns and sub-bottom profilers produce broadband sound with low pressure rise. Strandings to date which have been attributed to sound exposure related to date from military exercises using narrowband mid-frequency sonar with a much greater likelihood to cause physical damage (Balcomb and Claridge 2001, NOAA and USN, 2001, Hildebrand 2005).

The low intensity, low frequency, broadband sound associated with airguns and sub-bottom profilers, combined with the shutdown safety zone mitigation measure for the airgun would prevent physical damage to marine mammals. The vibracoring would also be unlikely to have the capability of causing physical damage to marine mammals because of its low intensity and short duration.

3. Potential Effects of Vessel Movement and Collisions

Vessel movement in the vicinity of marine mammals has the potential to result in either a behavioral response or a direct physical interaction. We discuss both scenarios here.

Behavioral Responses to Vessel Movement: There are limited data concerning marine mammal behavioral responses to vessel traffic and vessel noise, and a lack of consensus among scientists with respect to what these responses mean or whether they result in short-term or long-term adverse effects. In those cases where there is a busy shipping lane or where there is a large amount of vessel traffic, marine mammals may experience acoustic masking (Hildebrand, 2005) if they are present in the area (e.g., killer whales in Puget Sound; Foote et al., 2004; Holt et al., 2008). In cases where vessels actively approach marine mammals (e.g., whale watching or dolphin watching boats), scientists have documented that animals exhibit altered behavior such as increased swimming speed, erratic movement, and active avoidance behavior (Bursk, 1983; Acevedo, 1991; Baker and MacGibbon, 1991; Trites and Bain, 2000; Williams et al., 2002; Constantine et al., 2003), reduced blow interval (Ritcher et al., 2003), disruption of normal social behaviors (Lusseau, 2003; 2006), and the shift of behavioral activities which may increase energetic costs (Constantine et al., 2003; 2004). A detailed review of marine mammal reactions to ships and boats is available in Richardson et al. (1995). For each of the marine mammal taxonomy groups, Richardson et al. (1995) provides the following assessment regarding reactions to vessel traffic:

Pinnipeds: Reactions by pinnipeds to vessel disturbance largely involve relocation. Harbor seals hauled out on mud flats have been documented returning to the water in response to nearing boat traffic. Vessels that approach haulouts slowly may also elicit alert reactions without flushing from the haulout. Small boats with slow, constant speed elicit the least noticeable reactions. However, in Alaska specifically, harbor seals are documented to tolerate fishing vessels with no discernable reactions, and habituation is common (Burns in Johnson et al., 1989).

Porpoises: Harbor porpoises are often seen changing direction in the presence of vessel traffic. Avoidance has been documented up to 1km away from an approaching vessel, but the avoidance response is strengthened in closer proximity to vessels (Barlow, 1998; Palka, 1993). This avoidance behavior is not consistent across all porpoises, as Dall's porpoises have been observed approaching boats.

Toothed whales: In summary, toothed whales sometimes show no avoidance reaction to vessels, or even approach them. However, avoidance can occur, especially in response to vessels of types used to chase or hunt the animals. This may cause temporary displacement, but we know of no clear evidence that toothed whales have abandoned significant parts of their range because of vessel traffic.

Behavioral responses to stimuli are complex and influenced to varying degrees by a number of factors, such as species, behavioral contexts, geographical regions, source characteristics (moving or stationary, speed, direction, etc.), prior experience of the animal and physical status of the animal. For example, studies have shown that beluga whales' reactions varied when exposed to vessel noise and traffic. In some cases, naive beluga whales exhibited rapid swimming from ice-breaking vessels up to 80 km (49.7 mi) away, and showed changes in surfacing, breathing, diving, and group composition in the Canadian high Arctic where vessel traffic is rare (Finley et al., 1990). In other cases, beluga whales were more tolerant of vessels, but responded differentially to certain vessels and operating characteristics by reducing their calling rates (especially older animals) in the St. Lawrence River where vessel traffic is common (Blane and Jaakson, 1994). In Bristol Bay, Alaska, beluga whales continued to feed when surrounded by fishing vessels and resisted dispersal even when purposefully harassed (Fish and Vania, 1971).

In reviewing more than 25 years of whale observation data, Watkins (1986) concluded that whale reactions to vessel traffic were “modified by their previous experience and current activity: Habituation often occurred rapidly, attention to other stimuli or preoccupation with other activities sometimes overcame their interest or wariness of stimuli.” Watkins noticed that over the years of exposure to ships in the Cape Cod area, minke whales changed from frequent positive interest (e.g., approaching vessels) to generally uninterested reactions; fin whales changed from mostly negative (e.g., avoidance) to uninterested reactions; right whales apparently continued the same variety of responses (negative, uninterested, and positive responses) with little change; and humpbacks dramatically changed from mixed responses that were often negative to reactions that were often strongly positive. Watkins (1986) summarized that “whales near shore, even in regions with low vessel traffic, generally have become less wary of boats and their noises, and they have appeared to be less easily disturbed than previously. In particular locations with intense shipping and repeated approaches by boats (such as the whale-watching areas of Stellwagen Bank), more and more whales had positive reactions to familiar vessels, and they also occasionally approached other boats and yachts in the same ways.”

Vessel Strike

Ship strikes of cetaceans can cause major wounds, which may lead to the death of the animal. An animal at the surface could be struck directly by a vessel, a surfacing animal could hit the bottom of a vessel, or a vessel's propeller could injure an animal just below the surface. The severity of injuries typically depends on the size and speed of the vessel (Knowlton and Kraus, 2001; Laist et al., 2001; Vanderlaan and Taggart, 2007).

The most vulnerable marine mammals are those that spend extended periods of time at the surface in order to restore oxygen levels within their tissues after deep dives (e.g., the sperm whale). In addition, some baleen whales, such as the North Atlantic right whale, seem generally unresponsive to vessel sound, making them more susceptible to vessel collisions (Nowacek et al., 2004). These species are primarily large, slow moving whales. Smaller marine mammals (e.g., bottlenose dolphin) move quickly through the water column and are often seen riding the bow wave of large ships. Marine mammal responses to vessels may include avoidance and changes in dive pattern (NRC, 2003).

An examination of all known ship strikes from all shipping sources (civilian and military) indicates vessel speed is a principal factor in whether a vessel strike results in death (Knowlton and Kraus, 2001; Laist et al., 2001; Jensen and Silber, 2003; Vanderlaan and Taggart, 2007). In assessing records with known vessel speeds, Laist et al. (2001) found a direct relationship between the occurrence of a whale strike and the speed of the vessel involved in the collision. The authors concluded that most deaths occurred when a vessel was traveling in excess of 24.1 km/h (14.9 mph; 13 kts). Given the slow vessel speeds necessary for data acquisition, ship strike is unlikely to occur during this survey.

Entanglement

Entanglement can occur if wildlife becomes immobilized in survey lines, cables, nets, or other equipment that is moving through the water column. The proposed survey would require towing approximately 150 ft of cables. This size of the array generally carries a lower risk of entanglement for marine mammals. Wildlife, especially slow moving individuals, such as large whales, have a low probability of entanglement due to the low amount of slack in the lines, slow speed of the survey vessel, and onboard monitoring. Pinnipeds and porpoises are the least likely to entangle in equipment, as most documented cases of entanglement involve fishing gear and prey species (Gales et al., 2003). There are no reported cases of entanglement from geophysical equipment in the Cook Inlet area.

Anticipated Effects on Marine Mammal Habitat

The G&G Program survey areas are primarily within upper Cook Inlet, although the Marine Terminal survey area is located near Nikiski just south of the East Foreland (technically in Lower Cook Inlet), which includes habitat for prey species of marine mammals, including fish as well as invertebrates eaten by Cook Inlet beluga whales. This area contains Critical Habitat for Cook Inlet belugas, is near the breeding grounds for the local harbor seal population, and serves as an occasional feeding ground for killer whales and harbor porpoises. Cook Inlet is a large subarctic estuary roughly 299 km (186 mi) in length and averaging 96 km (60 mi) in width. It extends from the city of Anchorage at its northern end and flows into the Gulf of Alaska at its southernmost end. For descriptive purposes, Cook Inlet is separated into unique upper and lower sections, divided at the East and West Forelands, where the opposing peninsulas create a natural waistline in the length of the waterway, measuring approximately 16 km (10 mi) across (Mulherin et al. 2001).

Potential effects on beluga habitat would be limited to noise effects on prey; direct impact to benthic habitat from jack-up platform leg placement, and sampling with grabs, coring, and boring; and small discharges of drill cuttings and drilling mud associated with the borings. Portions of the survey areas include waters of Cook Inlet that are <9.1 m (30 ft) in depth and within 8.0 km (5.0 mi) of anadromous streams. Several anadromous streams (Three-mile Creek, Indian Creek, and two unnamed streams) enter the Cook Inlet within the survey areas. Other anadromous streams are located within 8.0 km (5.0 mi) of the survey areas. The survey program will not prevent beluga access to the mouths of these streams and will result in no short-term or long-term loss of intertidal or subtidal waters that are <9.1 m (30 ft) in depth and within 8.0 km (5.0 mi) of anadromous streams. Minor seafloor impacts will occur in these areas from grab samples, PCPTs, vibracores, or geotechnical borings but will have no effect on the area as beluga habitat once the vessel or jack-up platform has left. The survey program will have no effect on this habitat.

Cook Inlet beluga whales may avoid areas ensonified by the geophysical or geotechnical activities that generate sound with frequencies within the beluga hearing range and at levels above threshold values. This includes the chirp sub-bottom profiler with a radius of 184 m (604 ft), the boomer sub-bottom profiler with a radius of 263 m (863 ft), the airgun with a radius of 300 m (984 ft) and the vibracores with a radius of 2.54 km (1.58 mi). The sub-bottom profilers and the airgun will be operated from a vessel moving at speeds of about 4 kt. The operation of a vibracore has a duration of approximately 1-2 minutes. All of these activities will be conducted in relatively open areas of the Cook Inlet within Critical Habitat Area 2. Given the size and openness of the Cook Inlet in the survey areas, and the relatively small area and mobile/temporary nature of the zones of ensonification, the generation of sound by the G&G activities is not expected to result in any restriction of passage of belugas within or between critical habitat areas. The jack-up platform from which the geotechnical borings will be conducted will be attached to the seafloor with legs, and will be in place at a given location for up to 4-5 days, but given its small size (Table 4 in the application) would not result in any obstruction of passage by belugas.

Upper Cook Inlet comprises the area between Point Campbell (Anchorage) down to the Forelands, and is roughly 95 km (59 mi) in length and 24.9 km (15.5 mi) in width (Mulherin et al. 2001). Five major rivers (Knik, Matanuska, Susitna, Little Susitna, and Beluga) deliver freshwater to upper Cook Inlet, carrying a heavy annual sediment load of over 40 million tons of eroded materials and glacial silt (Brabets 1999). As a result, upper Cook Inlet is relatively shallow, averaging 18.3 m (60 ft) in depth. It is characterized by shoals, mudflats, and a wide coastal shelf, less than 17.9 m (59 ft) deep, extending from the eastern shore. A deep trough exists between Trading Bay and the Middle Ground Shoal, ranging from 35 to 77 m (114-253 ft) deep (NOAA Nautical Chart 16660). The substrate consists of a mixture of coarse gravels, cobbles, pebbles, sand, clay, and silt (Bouma et al. 1978, Rappeport 1982).

Upper Cook Inlet experiences some of the most extreme tides in the world, demonstrated by a mean tidal range from 4.0 m (13 ft) at the Gulf of Alaska end to 8.8 m (29 ft) near Anchorage (U.S. Army Corps of Engineers 2013). Tidal currents reach 3.9 kts per second (Mulherin et al. 2001) in upper Cook Inlet, increasing to 5.7-7.7 kts per second near the Forelands where the inlet is constricted. Each tidal cycle creates significant turbulence and vertical mixing of the water column in the upper inlet (U.S. Army Corps of Engineers 2013), and are reversing, meaning that they are marked by a period of slack tide followed an acceleration in the opposite direction (Mulherin et al. 2001).

Because of scouring, mixing, and sediment transport from these currents, the marine invertebrate community is very limited (Pentec 2005). Of the 50 stations sampled by Saupe et al. 2005 for marine invertebrates in Southcentral Alaska, their upper Cook Inlet station had by far the lowest abundance and diversity. Further, the fish community of upper Cook Inlet is characterized largely by migratory fish—eulachon and Pacific salmon—returning to spawning rivers, or outmigrating salmon smolts. Moulton (1997) documented only 18 fish species in upper Cook Inlet compared to at least 50 species found in lower Cook Inlet (Robards et al. 1999).

Lower Cook Inlet extends from the Forelands southwest to the inlet mouth demarked by an approximate line between Cape Douglas and English Bay. Water circulation in lower Cook Inlet is dominated by the Alaska Coastal Current (ACC) that flows northward along the shores of the Kenai Peninsula until it turns westward and is mixed by the combined influences of freshwater input from upper Cook Inlet, wind, topography, tidal surges, and the coriolis effect (Field and Walker 2003, MMS 1996). Upwelling by the ACC brings nutrient-rich waters to lower Cook Inlet and contributes to a biologically rich and productive ecology (Sambrotto and Lorenzen 1986). Tidal currents average 2-3 kt per second and are rotary in that they do not completely go slack before rotating around into an opposite direction (Gatto 1976, Mulherin et al. 2001). Depths in the central portion of lower Cook Inlet are 60-80 m (197-262 ft) and decrease steadily toward the shores (Muench 1981). Bottom sediments in the lower inlet are coarse gravel and sand that grade to finer sand and mud toward the south (Bouma 1978).

Coarser substrate support a wide variety of invertebrates and fish including Pacific halibut, Dungeness crab, tanner crab, pandalid shrimp, Pacific cod, and rock sole, while the soft-bottom sand and silt communities are dominated by polychaetes, bivalves and other flatfish (Field and Walker 2003). These species constitute prey species for several marine mammals in Cook Inlet, including pinnipeds and Cook Inlet belugas. Sea urchins and sea cucumbers are important otter prey and are found in shell debris communities. Razor clams are found all along the beaches of the Kenai Peninsula. In general, the lower Cook Inlet marine invertebrate community is of low abundance, dominated by polychaetes, until reaching the mouth of the inlet (Saupe et al. 2005). Overall, the lower Cook Inlet marine ecosystem is fed by midwater communities of phytoplankton and zooplankton, with the latter composed mostly of copepods and barnacle and crab larvae (Damkaer 1977, English 1980).

G&G Program activities that could potentially impact marine mammal habitats include sediment sampling (vibracore, boring, grab sampling) on the sea bottom, placement of the jack-up platform spud cans, and acoustical injury of prey resources. However, there are few benthic resources in the survey area that could be impacted by collection of the small samples (Saupe et al. 2005).

Acoustical effects to marine mammal prey resources are also limited. Christian et al. (2004) studied seismic energy impacts on male snow crabs and found no significant increases in physiological stress due to exposure to high sound pressure levels. No acoustical impact studies have been conducted to date on the above fish species, but studies have been conducted on Atlantic cod and sardine. Davis et al. (1998) cited various studies that found no effects to Atlantic cod eggs, larvae, and fry when received levels were 222 dB. Effects found were to larval fish within about 5.0 m (16 ft), and from air guns with volumes between 49,661 and 65,548 cm3 (3,000 and 4,000 in³). Similarly, effects to sardine were greatest on eggs and 2-day larvae, but these effects were greatest at 0.5 m (1.6 ft), and again confined to 5.0 m (16 ft). Further, Greenlaw et al. (1988) found no evidence of gross histological damage to eggs and larvae of northern anchovy exposed to seismic air guns, and concluded that noticeable effects would result only from multiple, close exposures. Based on these results, much lower energy impulsive geophysical equipment planned for this program would not damage larval fish or any other marine mammal prey resource.

Potential damage to the Cook Inlet benthic community will be limited to the actual surface area of the four spud cans that form the “foot” of each 0.762-m (30-in) diameter leg, the 42 0.1524-m (6-in) diameter borings, and the 55 0.0762-m (3-in) diameter vibracore samplings (plus several grab and PCPT samples). Collectively, these samples would temporarily damage about a hundred square meters of benthic habitat relative to the size (nearly 21,000 km2/8,108 mi2) of Cook Inlet. Overall, sediment sampling and acoustical effects on prey resources will have a negligible effect at most on the marine mammal habitat within the G&G Program survey area. Some prey resources might be temporarily displaced, but no long-term effects are expected.

The Cook Inlet 2015 G&G Program will result in a number of minor discharges to the waters of Cook Inlet. Discharges associated with the geotechnical borings will include: (1) The discharge of drill cuttings and drilling fluids and (2) the discharge of deck drainage (runoff of precipitation and deck wash water) from the geotechnical drilling platform. Other vessels associated with the G&G surveys will discharge wastewaters that are normally associated with the operation of vessels in transit including deck drainage, ballast water, bilge water, non-contact cooling water, and gray water.

The discharges of drill cuttings, drilling fluids, and deck drainage associated with the geotechnical borings will be within limitations authorized by the Alaska Department of Environmental Conservation under the Alaska Pollutant Discharge Elimination System. The drill cuttings consist of natural geologic materials of the seafloor sediments brought to the surface via the drill bit/drill stem of the rotary drilling operation, will be relatively minor in volume, and deposit over a very small area of Cook Inlet seafloor. The drilling fluids which are used to lubricate the bit, stabilize the hole, and viscosify the slurry for transport of the solids to the surface will consist of seawater and guar gum. Guar gum is a high-molecular weight polysaccharide (galactose and mannose units) derived from the ground seeds of the plant Cyampsis gonolobus. It is a non-toxic fluid also used as a food additive in soups, drinks, breads, and meat products.

Vessel discharges will be authorized under the U.S. Environmental Protection Agency's (EPA's) National Pollutant Discharge Elimination System (NPDES) Vessel General Permit (VGP) for Discharges Incidental to the Normal Operation of Vessels. Each vessel will have obtained authorization under the VGP and will discharge according to the conditions and limitations mandated by the permit. As required by statute and regulation, the EPA has made a determination that such discharges will not result in any unreasonable degradation of the marine environment, including:

• significant adverse changes in ecosystem diversity, productivity and stability of the biological community within the area of discharge and surrounding biological communities,
• threat to human health through direct exposure to pollutants or through consumption of exposed aquatic organisms, or
• loss of aesthetic, recreational, scientific or economic values which is unreasonable in relation to the benefit derived from the discharge.

Mitigation

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

To mitigate potential acoustical impacts to local marine mammals, Protected Species Observers (PSOs) will operate aboard the vessels from which the chirper, boomer, airgun, and vibracorer will be deployed. The PSOs will implement the mitigation measures described in the Marine Mammal Monitoring and Mitigation Plan (Appendix A of the application). These mitigations include: (1) Establishing safety zones to ensure marine mammals are not injured by sound pressure levels exceeding Level A injury thresholds; (2) shutting down the airgun when required to avoid harassment of beluga whales approaching the 160-dB disturbance zone; and (3) timing survey activity to avoid concentrations of beluga whales on a seasonal basis.

Before chirper, boomer, airgun, and vibracoring operations begin each day and before restarting operations after a shutdown of 15 minutes or greater, the PSOs will “clear” both the Level A and Level B Zones of Influence (ZOIs—area from the source to the 160dB or 180/190dB isopleths) of marine mammals by intensively surveying these ZOIs prior to activity to confirm that marine mammals are not seen in the applicable area. All three geophysical activities (boomer, chirp, airgun) will be shut down in mid-operation at the approach to any marine mammal to the Level A safety zone, and at the approach of an ESA-listed beluga whale to the Level B harassment zone for these sources. The geotechnical vibracoring lasts only one or two minutes and shutdowns are likely impossible. Finally, the G&G Program will be planned to avoid high beluga whale density areas. This would be achieved by conducting surveys at the Marine Terminal and the southern end of the pipeline survey area when beluga whales are farther north, feeding near the Susitna Delta, and completing activities in the northern portion of the pipeline survey area when the Cook Inlet beluga whales have begun to disperse from the Susitna Delta and other summer concentration areas.

Vessel-Based Visual Mitigation Monitoring

EMALL will hire qualified and NMFS-approved PSOs. These PSOs will be stationed aboard the geophysical survey source or support vessels during sub-bottom profiling, air gun, and vibracoring operations. A single senior PSO will be assigned to oversee all Marine Mammal Mitigation and Monitoring Program mandates and function as the on-site person-in-chargeimplementing the 4MP.

Generally, two PSOs will work on a rotational basis during daylight hours with shifts of 4 to 6 hours, and one PSO on duty on each source vessel at all times. Work days for an individual PSO will not exceed 12 hours in duration. Sufficient numbers of PSOs will be available and provided to meet requirements.

Roles and responsibilities of all PSOs include the following:

• Accurately observe and record sensitive marine mammal species;
• Follow monitoring and data collection procedures; and
• Ensure mitigation measures are followed.

PSOs will be stationed at the best available vantage point on the source vessels. PSOs will scan systematically with the unaided eye and 7x50 reticle binoculars. As necessary, new PSOs will be paired with experienced PSOs to ensure that the quality of marine mammal observations and data recording are consistent.

All field data collected will be entered by the end of the day into a custom database using a notebook computer. Weather data relative to viewing conditions will be collected hourly, on rotation, and when sightings occur and include the following:

• Sea state;
• Wind speed and direction;
• Sun position; and
• Percent glare.

The following data will be collected for all marine mammal sightings:

• Bearing and distance to the sighting;
• Species identification;
• Behavior at the time of sighting (e.g., travel, spy-hop, breach, etc.);
• Direction and speed relative to vessel;
• Reaction to activities—changes in behavior (e.g., none, avoidance, approach, paralleling, etc.);
• Group size;
• Orientation when sighted (e.g., toward, away, parallel, etc.);
• Closest point of approach;
• Sighting cue (e.g., animal, splash, birds, etc.);
• Physical description of features that were observed or determined not to be present in the case of unknown or unidentified animals;
• Time of sighting;
• Location, speed, and activity of the source and mitigation vessels, sea state, ice cover, visibility, and sun glare; and positions of other vessel(s) in the vicinity, and
• Mitigation measure taken—if any.

All observations and shut downs will be recorded in a standardized format and data entered into a custom database using a notebook computer. Accuracy of all data will be verified daily by the PIC or designated PSO by a manual verification. These procedures will reduce errors, allow the preparation of short-term data summaries, and facilitate transfer of the data to statistical, graphical, or other programs for further processing and archiving. PSOs will conduct monitoring during daylight periods (weather permitting) during G&G activities, and during most daylight periods when G&G activities are temporarily suspended.

Shutdown Procedures

If any marine mammal is seen approaching the Level A injury zone for the air gun, chirp, or boomer, these sources will be shut down. If ESA-listed marine mammals (e.g., beluga whales) are observed approaching the Level B harassment zone for the air gun, chirp, or boomer, these sources will be shut down. The PSOs will ensure that the harassment zone is clear of marine mammal activity before vibracoring will occur. Given that vibracoring lasts only about a minute or two, shutdown actions are not practicable.

Resuming Airgun Operations After a Shutdown

A full ramp-up after a shutdown will not begin until there has been a minimum of 30 minutes of observation of the applicable exclusion zone by PSOs to assure that no marine mammals are present. The entire exclusion zone must be visible during the 30-minute lead-in to a full ramp up. If the entire exclusion zone is not visible, then ramp-up from a cold start cannot begin. If a marine mammal(s) is sighted within the injury exclusion zone during the 30-minute watch prior to ramp-up, ramp-up will be delayed until the marine mammal(s) is sighted outside of the zone or the animal(s) is not sighted for at least 15-30 minutes: 15 minutes for small odontocetes and pinnipeds (e.g. harbor porpoises, harbor seals), or 30 minutes for large odontocetes (e.g., killer whales and beluga whales).

Speed and Course Alterations

If a marine mammal is detected outside the Level A injury exclusion zone and, based on its position and the relative motion, is likely to enter that zone, the vessel's speed and/or direct course may, when practical and safe, be changed to also minimize the effect on the survey program. The marine mammal activities and movements relative to the sound source and support vessels will be closely monitored to ensure that the marine mammal does not approach within the applicable exclusion radius. If the mammal appears likely to enter the exclusion radius, further mitigative actions will be taken, i.e., either further course alterations or shut down of the active sound sources considered in this Authorization.

Mitigation Required by NMFS

Special Procedures for Situations or Species of Concern

The following additional protective measures for beluga whales and groups of five or more killer whales and harbor porpoises are required. Specifically, a 160-dB vessel monitoring zone would be established and monitored in Cook Inlet during all seismic surveys. If a beluga whale or groups of five or more killer whales and/or harbor porpoises are visually sighted approaching or within the 160-dB disturbance zone, survey activity would not commence until the animals are no longer present within the 160-dB disturbance zone. Whenever Cook Inlet beluga whales or groups of five or more killer whales and/or harbor porpoises are detected approaching or within the 160-dB disturbance zone, the boomer, chirp, and airgun may be powered down before the animal is within the 160-dB disturbance zone, as an alternative to a complete shutdown. If the PSO determines a power down is not sufficient, the sound source(s) shall be shut-down until the animals are no longer present within the 160-dB zone.

Mitigation Exclusion Zones

NMFS requires that EMALL will not operate the chirp, boomer, vibracore, or airgun within 10 miles (16 km) of the mean lower low water (MLLW) line of the Susitna Delta (Beluga River to the Little Susitna River) between April 15 and October 15. The purpose of this mitigation measure is to protect beluga whales in the designated critical habitat in this area that is important for beluga whale feeding and calving during the spring and fall months. The range of the setback required by NMFS was designated to protect this important habitat area and also to create an effective buffer where sound does not encroach on this habitat. This seasonal exclusion will be in effect from April 15th to October 15th annually. Activities can occur within this area from October 16th-April 14th.

Mitigation Conclusions

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

• The manner in which, and the degree to which, the successful implementation of the measure is expected to minimize adverse impacts to marine mammals;
• The proven or likely efficacy of the specific measure to minimize adverse impacts as planned; and
• The practicability of the measure for applicant implementation.

Any mitigation measure(s) prescribed by NMFS should be able to accomplish, have a reasonable likelihood of accomplishing (based on current science), or contribute to the accomplishment of one or more of the general goals listed here:

• Avoidance or minimization of injury or death of marine mammals wherever possible (goals 2, 3, and 4 may contribute to this goal).
• A reduction in the numbers of marine mammals (total number or number at biologically important time or location) exposed to airgun operations that we expect to result in the take of marine mammals (this goal may contribute to 1, above, or to reducing harassment takes only).
• A reduction in the number of times (total number or number at biologically important time or location) individuals would be exposed to airgun operations that we expect to result in the take of marine mammals (this goal may contribute to 1, above, or to reducing harassment takes only).
• A reduction in the intensity of exposures (either total number or number at biologically important time or location) to airgun operations that we expect to result in the take of marine mammals (this goal may contribute to a, above, or to reducing the severity of harassment takes only).
• Avoidance or minimization of adverse effects to marine mammal habitat, paying special attention to the food base, activities that block or limit passage to or from biologically important areas, permanent destruction of habitat, or temporary destruction/disturbance of habitat during a biologically important time.
• For monitoring directly related to mitigation—an increase in the probability of detecting marine mammals, thus allowing for more effective implementation of the mitigation.

Based on the evaluation of EMALL's measures, as well as other measures required by NMFS, NMFS has determined that the mitigation measures provide the means of effecting the least practicable impact on marine mammal species or stocks and their habitat, paying particular attention to rookeries, mating grounds, and areas of similar significance. Measures to ensure availability of such species or stock for taking for certain subsistence uses are discussed later in this document (see “Impact on Availability of Affected Species or Stock for Taking for Subsistence Uses” section).

Monitoring and Reporting

Weekly Field Reports

Weekly reports will be submitted to NMFS no later than the close of business (Alaska Time) each Thursday during the weeks when in-water G&G activities take place. The reports will cover information collected from Wednesday of the previous week through Tuesday of the current week. The field reports will summarize species detected, in-water activity occurring at the time of the sighting, behavioral reactions to in-water activities, and the number of marine mammals exposed to harassment level noise.

Monthly Field Reports

Monthly reports will be submitted to NMFS for all months during which in-water G&G activities take place. The reports will be submitted to NMFS no later than five business days after the end of the month. The monthly report will contain and summarize the following information:

• Dates, times, locations, heading, speed, weather, sea conditions (including Beaufort Sea state and wind force), and associated activities during the G&G Program and marine mammal sightings.
• Species, number, location, distance from the vessel, and behavior of any sighted marine mammals, as well as associated G&G activity (number of shut downs), observed throughout all monitoring activities.
• An estimate of the number (by species) of: (i) Pinnipeds that have been exposed to the authorized geophysical or geotechnical activity (based on visual observation) at received levels greater than or equal to 160 dB re 1 µPa (rms) and/or 190 dB re 1 µPa (rms) with a discussion of any specific behaviors those individuals exhibited; and (ii) cetaceans that have been exposed to the geophysical activity (based on visual observation) at received levels greater than or equal to 160 dB re 1 µPa (rms) and/or 180 dB re 1 µPa (rms) with a discussion of any specific behaviors those individuals exhibited.
• An estimate of the number (by species) of pinnipeds and cetaceans that have been exposed to the geotechnical activity (based on visual observation) at received levels greater than or equal to 120 dB re 1 µPa (rms) with a discussion of any specific behaviors those individuals exhibited.
• A description of the implementation and effectiveness of the: (i) Terms and conditions of the Biological Opinion's Incidental Take Statement; and (ii) mitigation measures of the IHA. For the Biological Opinion, the report shall confirm the implementation of each Term and Condition, as well as any conservation recommendations, and describe their effectiveness, for minimizing the adverse effects of the action on ESA-listed marine mammals.

90-Day Technical Report

A report will be submitted to NMFS within 90 days after the end of the project or at least 60 days before the request for another IHA for the next open water season to enable NMFS to incorporate observation data into the next Authorization. The report will summarize all activities and monitoring results (i.e., vessel-based visual monitoring) conducted during in-water G&G surveys. The Technical Report will include the following:

• Summaries of monitoring effort (e.g., total hours, total distances, and marine mammal distribution through the study period, accounting for sea state and other factors affecting visibility and detectability of marine mammals).
• Analyses of the effects of various factors influencing detectability of marine mammals (e.g., sea state, number of observers, and fog/glare).
• Species composition, occurrence, and distribution of marine mammal sightings, including date, water depth, numbers, age/size/gender categories (if determinable), group sizes, and ice cover.
• Analyses of the effects of survey operations.
• Sighting rates of marine mammals during periods with and without G&G survey activities (and other variables that could affect detectability), such as: (i) Initial sighting distances versus survey activity state; (ii) closest point of approach versus survey activity state; (iii) observed behaviors and types of movements versus survey activity state; (iv) numbers of sightings/individuals seen versus survey activity state; (v) distribution around the source vessels versus survey activity state; and (vi) estimates of Level B harassment based on presence in the 120 or 160 dB harassment zone.

Notification of Injured or Dead Marine Mammals

In the unanticipated event that the specified activity leads to an injury of a marine mammal (Level A harassment) or mortality (e.g., ship-strike, gear interaction, and/or entanglement), EMALL would immediately cease the specified activities and immediately report the incident to the Chief of the Permits and Conservation Division, Office of Protected Resources, and the Alaska Regional Stranding Coordinators at NMFS. The report would include the following information:

• Time, date, and location (latitude/longitude) of the incident;
• Name and type of vessel involved;
• Vessel's speed during and leading up to the incident;
• Description of the incident;
• Status of all sound source use in the 24 hours preceding the incident;
• Water depth;
• Environmental conditions (e.g., wind speed and direction, Beaufort sea state, cloud cover, and visibility);
• Description of all marine mammal observations in the 24 hours preceding the incident;
• Species identification or description of the animal(s) involved;
• Fate of the animal(s); and
• Photographs or video footage of the animal(s) (if equipment is available).

Activities would not resume until NMFS is able to review the circumstances of the event. EMALL would work with NMFS to minimize reoccurrence of such an event in the future. The G&G Program would not resume activities until formally notified by NMFS via letter, email, or telephone.

In the event that the G&G Program discovers an injured or dead marine mammal, and the lead PSO determines that the cause of the injury or death is unknown and the death is relatively recent (i.e., in less than a moderate state of decomposition as described in the next paragraph), the Applicant would immediately report the incident to the Chief of the Permits and Conservation Division, Office of Protected Resources, NMFS, and the NMFS Alaska Stranding Hotline and/or by email to the Alaska Regional Stranding Coordinators. The report would include the same information identified in the paragraph above. Activities would be able to continue while NMFS reviews the circumstances of the incident. NMFS would work with the Applicant to determine if modifications in the activities are appropriate.

In the event that the G&G Program discovers an injured or dead marine mammal, and the lead PSO determines that the injury or death is not associated with or related to the activities authorized in the IHA (e.g., previously wounded animal, carcass with moderate to advanced decomposition, or scavenger damage), EMALL would report the incident to the Chief of the Permits and Conservation Division, Office of Protected Resources, NMFS, and the NMFS Alaska Stranding Hotline and/or by email to the Alaska Regional Stranding Coordinators, within 24 hours of the discovery. EMALL would provide photographs or video footage (if available) or other documentation of the stranded animal sighting to NMFS and the Marine Mammal Stranding Network.

Estimated Take by Incidental Harassment

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

Acoustic stimuli (i.e., increased underwater sound) generated during the operation of the airgun or the sub-bottom profiler have the potential to result in the behavioral disturbance of some marine mammals. NMFS believes that take from the operation of the vibracore is unlikely but possible and is issuing take at the request of the applicant. Thus, NMFS proposes to authorize take by Level B harassment resulting from the operation of the sound sources for the proposed survey based upon the current acoustic exposure criteria shown in Table 3.

Table 3—NMFS' Current Acoustic Exposure Criteria

Criterion	Criterion definition	Threshold
Level A Harassment (Injury)	Permanent Threshold Shift (PTS) (Any level above that which is known to cause TTS)	180 dB re 1 microPa-m (cetaceans)/190 dB re 1 microPa-m (pinnipeds) root mean square (rms)
Level B Harassment	Behavioral Disruption (for impulse noises) Behavioral Disruption (for continuous noises)	160 dB re 1 microPa-m (rms) 120 dB re 1 microPa-m (rms)

NMFS' practice is to apply the 120 or 160 dB re: 1 µPa received level threshold (whichever is appropriate) for underwater impulse sound levels to determine whether take by Level B harassment occurs.

All four types of survey equipment addressed in the application will be operated from the geophysical source vessels that will either be moving steadily across the ocean surface (chirper, boomer, airgun), or from station to station (vibracoring). The numbers of marine mammals that might be exposed to sound pressure levels exceeding NMFS Level B harassment threshold levels due to G&G surveys, without mitigation, were determined by multiplying the average raw density for each species by the daily ensonified area, and then multiplying that figure by the number of days each sound source is estimated to be in use. The chirp and boomer activities were combined into one calculation because they will be operating concurrently, using the daily ensonified area of the boomer, as it is a slightly larger isopleth. The exposure estimates for each activity were then summed to provide total exposures for the duration of the project. The exposure estimates for the activity are detailed below. Although NMFS believes that take of marine mammals from vibracore is extremely unlikely, it has been included in this authorization out of an abundance of caution and at the request of the applicant.

Ensonified Area

The ZOI is the area ensonified by a particular sound source greater than threshold levels (120 dB for continuous and 160 dB for impulsive). The radius of the ZOI for a particular equipment was determined by applying the source sound pressure levels described in Table 6 of the application to Collins et al.'s (2007) attenuation model of 18.4 Log(r)−0.00188 derived from Cook Inlet. For those equipment generating loud underwater sound within the audible hearing range of marine mammals (<200 kHz), the distance to threshold ranges between 184 m (604 ft) and 2.54 km (1.58 mi), with ZOIs ranging between 0.106 and 20.26 km2 (0.041-7.82 mi2) (Table 4).

Table 4—Summary of Distances to the NMFS Thresholds and Associated ZOIs

Survey equipment	Distance to 160 dB isopleth 1 m (ft)	Distance to 120 dB isopleth 1 km (mi)	160 dB ZOI km2 (mi2)	120 dB ZOI km2 (mi2)
Sub-bottom Profiler (Chirp)	184 (604)	N/A	0.106 (0.041)	N/A
Sub-bottom Profiler (Boomer)	263 (863)	N/A	0.217 (0.084)	N/A
Airgun	300 (984)	N/A	0.283 (0.109)	N/A
Vibracore	N/A	2.54 (1.58)	N/A	20.26 (7.82)
1 Calculated by applying Collins et al. (2007) spreading formula to source levels in Table 2.

Marine Mammal Densities

Density estimates were derived for harbor porpoises, killer whales, and harbor seals from NMFS 2002-2012 Cook Inlet survey data as described below in Section 6.1.2.1 and shown in Table 8. The beluga whale exposure estimates were calculated using density estimates from Goetz et al. (2012) as described in Section 6.1.2.2.

Harbor Porpoise, Killer Whale, Harbor Seal

Density estimates were calculated for all marine mammals (except beluga whales) by using aerial survey data collected by NMFS in Cook Inlet between 2002 and 2012 (Rugh et al. 2002, 2003, 2004a, 2004b, 2005a, 2005b, 2005c, 2006, 2007; Shelden et al. 2008, 2009, 2010; Hobbs et al. 2011, Shelden et al. 2012) and compiled by Apache, Inc. (Apache IHA application 2014). To estimate the average raw densities of marine mammals, the total number of animals for each species observed over the 11-year survey period was divided by the total area of 65,889 km² (25,540 mi²) surveyed over the 11 years. The aerial survey marine mammal sightings, survey effort (area), and derived average raw densities are provided in Table 5.

Table 5—Raw Density Estimates for Cook Inlet Marine Mammals Based on NMFS Aerial Surveys

Species	Number of animals	NMFS survey area km 2 (mi 2)	Mean raw density animals/km 2 (animals/mi 2)
Harbor Porpoise	249	65,889 (25,440)	0.0033 (0.0098)
Killer Whale1	42	65,889 (25,440)	0.0008 (0.0017)
Harbor Seal	16,117	65,889 (25,440)	0.28 (0.6335)
1 Density is for all killer whales regardless of the stock although all killer whales in the upper Cook Inlet are thought to be transient.

These raw densities were not corrected for animals missed during the aerial surveys as no accurate correction factors are currently available for these species; however, observer error may be limited as the NMFS surveyors often circled marine mammal groups to get an accurate count of group size. The harbor seal densities are probably biased upwards given that a large number of the animals recorded were of large groups hauled out at river mouths, and do not represent the distribution in the waters where the G&G activity will actually occur. However, these data are the most comprehensive available for Cook Inlet harbor seals and therefore constitute the best available science.

Beluga Whale

Goetz et al. (2012) modeled aerial survey data collected by the NMFS between 1993 and 2008 and developed specific beluga summer densities for each 1-km2 cell of Cook Inlet. The results provide a more precise estimate of beluga density at a given location than simply multiplying all aerial observations by the total survey effort given the clumped distribution of beluga whales during the summer months. To develop a density estimate associated with planned action areas (i.e., Marine Terminal and pipeline survey areas), the ensonified area associated with each activity was overlain a map of the 1-km density cells, the cells falling within each ensonified area were quantified, and an average cell density was calculated. The summary of the density results is found in Table 9 in the application. The associated ensonified areas and beluga density contours relative to the action areas are shown in Table 6.

Table 6—Mean Raw Densities of Beluga Whales Within the Action Areas Based on Goetz et al. (2012) Cook Inlet Beluga Whale Distribution Modeling

Action area	Number of cells	Mean density (animals/km2)	Density range (animals/km2)
Marine Terminal Survey Area	386	0.000166	0.000021-0.001512
Pipeline Survey Area	571	0.011552	0.000275-0.156718

Activity Duration

The Cook Inlet 2015 G&G Program is expected to require approximately 12 weeks (84 days) to complete. During approximately 63 of these days, the chirp and boomer sub-bottom profiler will produce the loudest sound levels. Airgun use will occur during approximately 7 days and will occur only near the proposed Marine Terminal. The airgun activity will occur during the summer when beluga whale use of Cook Inlet is primarily concentrated near the Susitna Delta, approximately 65 km (40 mi) north of the airgun survey area. Vibracoring, with its large ZOI, will occur intermittently over approximately 14 days. The applicant provided an estimate of 50 miles per day that the survey vessel could travel.

Exposure Calculations

The numbers of marine mammals that might be exposed to sound pressure levels exceeding NMFS Level B harassment threshold levels due to G&G surveys, without mitigation, were determined by multiplying the average raw density for each species by the daily ensonified area, then multiplying by the number of days each sound source is estimated to be in use. While this method produces a good estimate of the number of instances of take, it is likely an overestimate of the number of individual marine mammals taken because it assumes that entirely new individuals are taken on subsequent days and that no animals are taken more than once. The chirp and boomer activities were combined to calculate exposure from days of activities in the Upper Cook Inlet area and the Lower Cook Inlet area because they will be operating concurrently. The exposure estimates for each activity were then summed to provide total exposures for the duration of the project. The exposure estimates for the activity are detailed below.

Table 7—Exposure Estimates for Activity

Species	Density	Boomer—Upper	Boomer—Lower	Airgun	Vibracore—Upper	Vibracore—Lower	Total	Authorization
Beluga	0.0012 .00017	18.18	0.18	0.056	5.15	0.11	23.69	24
Killer whale	0.00082	1.29	0.91	0.28	0.37	0.55	3.39	5
Harbor seal	0.28	444.52	312.37	95.99	125.92	188.89	1,167.68	1,168
Harbor porpoise	0.0033	5.18	3.64	1.12	1.47	2.20	13.60	20

NMFS recognizes that in addition to what was mentioned above, there are other factors that contribute to an overestimate of exposures,, e.g., the fact that many of these technologies will be operating simultaneously, and not exposing animals in separate instances for the duration of the survey period. Additionally, the beamwidth and tilt angle of the sub-bottom profiler are not factored into the characterization of the sound field, making it conservative and large, creating additional overestimates in take estimation.

The possibility of Level A exposure was analyzed, however the distances to 180 dB/190 dB isopleths are incredibly small, ranging from 0 to 26 meters. The number of exposures, without accounting for mitigation or likely avoidance of louder sounds, is small for these zones, and with mitigation and the likelihood of detecting marine mammals within this small area combined with the likelihood of avoidance, it is likely these takes can be avoided. The only technology that would not shutdown is the vibracore, which has a distance to Level A isopleth (180 dB) of 3 meters. Therefore, authorization of Level A take is not necessary.

NMFS will authorize the following takes by Level B harassment:

Table 8—Authorizations

Species	Exposure estimate	Take authorized	Percent of stock or population	Population trend
Beluga	23.69	24	7.06	Decreasing.
Killer whale	3.39	5	1.44 transient	Transient—Stable.
Harbor seal	1,167.68	1,168	5.10	Stable.
Harbor porpoise	13.60	20	0.064	No reliable info.

Analysis and Determinations

Negligible Impact

Negligible impact is “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” (50 CFR 216.103). The lack of likely adverse effects on annual rates of recruitment or survival (i.e., population level effects) forms the basis of a negligible impact finding. Thus, an estimate of the number of takes, alone, is not enough information on which to base an impact determination. In addition to considering estimates of the number of marine mammals that might be “taken” through behavioral harassment, NMFS must consider other factors, such as the likely nature of any responses (their intensity, duration, etc.), the context of any responses (critical reproductive time or location, migration, etc.), as well as the number and nature of estimated Level A harassment takes, the number of estimated mortalities, effects on habitat, and the status of the species.

To avoid repetition, except where otherwise identified, the discussion of our analyses applies to all the species listed in Table 8, given that the anticipated effects of this project on marine mammals are expected to be relatively similar in nature. Where there is information about specific impacts to, or about the size, status, or structure of, any species or stock that would lead to a different analysis for this activity, species-specific factors are identified and analyzed.

In making a negligible impact determination, NMFS considers:

• The number of anticipated injuries, serious injuries, or mortalities;
• The number, nature, and intensity, and duration of Level B harassment; and
• The context in which the takes occur (e.g., impacts to areas of significance, impacts to local populations, and cumulative impacts when taking into account successive/contemporaneous actions when added to baseline data);
• The status of stock or species of marine mammals (i.e., depleted, not depleted, decreasing, increasing, stable, impact relative to the size of the population);
• Impacts on habitat affecting rates of recruitment/survival; and
• The effectiveness of monitoring and mitigation measures to reduce the number or severity of incidental take.

As discussed in the Potential Effects section, temporary or permanent threshold shift, non-auditory physical or physiological effects, ship strike, entanglement are not expected to occur. Given the required mitigation and related monitoring, no injuries or mortalities are anticipated to occur to any species as a result of EMALL's proposed survey in Cook Inlet, and none are authorized. Animals in the area are not expected to incur hearing impairment (i.e., TTS or PTS) or non-auditory physiological effects due to low source levels and the fact that most marine mammals would more likely avoid a loud sound source rather than swim in such close proximity as to result in TTS or PTS. The most likely effect from the proposed action is localized, short-term behavioral disturbance from active acoustic sources. The number of takes that are anticipated and authorized are expected to be limited to short-term Level B behavioral harassment for all stocks for which take is authorized. This is largely due to the short time scale of the proposed activity, the low source levels for many of the technologies proposed to be used, as well as the required mitigation. The technologies do not operate continuously over a 24-hour period. Rather, airguns are operational for a few hours at a time for 7 days, with the sub-bottom profiler chirp and boomer operating for 63 days, and the vibracore operating over 14 days.

The addition of five vessels, and noise due to vessel operations associated with the survey, would not be outside the present experience of marine mammals in Cook Inlet, although levels may increase locally. Potential impacts to marine mammal habitat were discussed previously in this document (see the “Anticipated Effects on Habitat” section). Although some disturbance is possible to food sources of marine mammals, the impacts are anticipated to be minor enough as to not affect annual rates of recruitment or survival of marine mammals in the area. Based on the size of Cook Inlet where feeding by marine mammals occurs versus the localized area of the marine survey activities, any missed feeding opportunities in the direct project area would be minor based on the fact that other feeding areas exist elsewhere.

Taking into account the mitigation measures that are planned, effects on cetaceans are generally expected to be restricted to avoidance of a limited area around the survey operation and short-term changes in behavior, falling within the MMPA definition of “Level B harassment.” Shut-downs are required for belugas and groups of killer whales or harbor porpoises when they approach the 160dB disturbance zone, to further reduce potential impacts to these populations. Visual observation by trained PSOs is also implemented to reduce the impact of the proposed activity by informing operators of marine mammals approaching the relevant disturbance or injury zones. Animals are not expected to permanently abandon any area that is surveyed, and any behaviors that are interrupted during the activity are expected to resume once the activity ceases. Only a small portion of marine mammal habitat will be affected at any time, and other areas within Cook Inlet will be available for necessary biological functions.

Odontocete (including Cook Inlet beluga whales, killer whales, and harbor porpoises) reactions to seismic energy pulses are usually assumed to be limited to shorter distances from the airgun(s) than are those of mysticetes, in part because odontocete low-frequency hearing is assumed to be less sensitive than that of mysticetes. This information supports the idea that the numerated takes for odonotocetes are likely on the lower end of severity in the terms of responses that rise to the level of a take.

Beluga Whales

Cook Inlet beluga whales are listed as endangered under the ESA. This stock is also considered depleted under the MMPA. The estimated annual rate of decline for Cook Inlet beluga whales was 0.6 percent between 2002 and 2012. The authorization of take by Level B harassment of 24 Cook Inlet beluga whales represents 7.06 percent of the population.

Belugas in the Canadian Beaufort Sea in summer appear to be fairly responsive to seismic energy, with few being sighted within 10-20 km (6-12 mi) of seismic vessels during aerial surveys (Miller et al., 2005). However, as noted above, Cook Inlet belugas are more accustomed to anthropogenic sound than beluga whales in the Beaufort Sea. Therefore, the results from the Beaufort Sea surveys do not directly translate to potential reactions of Cook Inlet beluga whales. Also, due to the dispersed distribution of beluga whales in Cook Inlet during winter and the concentration of beluga whales in upper Cook Inlet from late April through early fall, belugas would likely occur in small numbers in the majority of EMALL's proposed survey area during the majority of EMALL's annual operational timeframe of August through December. For the same reason, as well as the mitigation measure that requires shutting down for belugas seen approaching the 160dB disturbance zone, and the likelihood of avoidance at high levels, it is unlikely that animals would be exposed to received levels capable of causing injury.

Given the large number of vessels in Cook Inlet and the apparent habituation to vessels by Cook Inlet beluga whales and the other marine mammals that may occur in the area, vessel activity from the two source vessels, tug and jack-up rig and associated vessel noise is not expected to have effects that could cause significant or long-term consequences for individual marine mammals or their populations, given that vessels will operate for a maximum of 84 days.

In addition, NMFS has seasonally restricted survey operations in the area known to be important for beluga whale feeding, calving, or nursing. The primary location for these biological life functions occurs in the Susitna Delta region of upper Cook Inlet. NMFS required EMALL to implement a 16 km (10 mi) seasonal exclusion from survey operations in this region from April 15-October 15. The highest concentrations of belugas are typically found in this area from early May through September each year. NMFS has incorporated a 2-week buffer on each end of this seasonal use timeframe to account for any anomalies in distribution and marine mammal usage.

Killer Whales

The authorization of take by Level B harassment of 5 killer whales represents only 1.44 percent of the population. Killer whales are not encountered as frequently in Cook Inlet as some of the other species in this analysis, however when sighted they are usually in groups. The addition of a mitigation measure to shutdown if a group of 5 or more killer whales is seen approaching the 160 dB zone is intended to minimize any impact to an aggregation of killer whales if encountered. The killer whales in the survey area are also thought to be transient killer whales and therefore rely on the habitat in the EMALL survey area less than other resident species.

Harbor Porpoise

The authorization of take by Level B harassment for 20 harbor porpoises represents only 0.064 percent of the population. Harbor porpoises are among the most sensitive marine mammal species with regard to behavioral response and anthropogenic noise. They are known to exhibit behavioral responses to operation of seismic airguns, pingers, and other technologies at low thresholds. However, they are abundant in Cook Inlet and therefore the authorized take is unlikely to affect recruitment or status of the population in any way. In addition, mitigation measures include shutdowns for groups of more than 5 harbor porpoises that will minimize the amount of take to the local harbor porpoise population. This mitigation as well as the short duration and low source levels of the proposed activity will reduce the impact to the harbor porpoises found in Cook Inlet.

Harbor Seal

The authorization of take by Level B harassment for 1,168 harbor seals represents only 5.1% of a stable population. Observations during other anthropogenic activities in Cook Inlet have reported large congregations of harbor seals hauling out in upper Cook Inlet. However, mitigation measures, such as vessel speed, course alteration, and visual monitoring, and time-area restrictions will be implemented to help reduce impacts to the animals. Additionally, this activity does not encompass a large number of known harbor seal haulouts, particularly as this activity proposes operations traversing across the Inlet, as opposed to entirely nearshore activities. While some harbor seals will likely be exposed, the required mitigation along with their smaller aggregations in water than on shore should minimize impacts to the harbor seal population. Additionally, the short duration of the survey, and the use of visual observers to inform shutdowns and ramp up delays should further reduce the severity of behavioral reactions to Cook Inlet harbor seals. Therefore, the exposure of pinnipeds to sounds produced by this phase of EMALL's proposed survey is not anticipated to have an effect on annual rates of recruitment or survival on those species or stocks.

Based on the analysis contained herein of the likely effects of the specified activity on marine mammals and their habitat, and taking into consideration the implementation of the required monitoring and mitigation measures, NMFS finds that the total annual marine mammal take from EMALL's proposed survey will have a negligible impact on the affected marine mammal species or stocks (see Table 8).

Although NMFS believes it is unlikely the operation of the vibracore would result in the take of marine mammals and did not propose to authorize take by vibracore in the Federal Register notice of the proposed Authorization, we note here that take from vibracoring activities has been included in the Final Authorization out of an abundance of caution and at the request of the applicant. Take by Level B harassment from vibracoring accounts for approximately 25 percent of the take authorized for the entire survey, ranging from 0.9 killer whales to 313 harbor seals. The vibracoring activity is proposed to occur at 55 locations across the Inlet from the Forelands, north to the upper end of Cook Inlet. However, the actual noise-producing activity will only occur for only 90 seconds at a time, during which PSOs will be observing for marine mammals. The limited scope and duration of vibracoring makes it extremely unlikely that take by Level B harassment would occur during the vibracore portion of the operation. Nonetheless, we included the potential take from vibracore in our analysis above, and as we indicated, we found that there would be a negligible impact on the affect species or stocks from the total takes, including any that are authorized for vibracore.

Small Numbers Analysis

The requested takes authorized annually represent 7.06 percent of the Cook Inlet beluga whale population of approximately 340 animals (Allen and Angliss, 2014), 1.44 percent of the Gulf of Alaska, Aleutian Island and Bering Sea stock of killer whales (345 transients), and 0.064 percent of the Gulf of Alaska stock of approximately 31,046 harbor porpoises. The take requests presented for harbor seals represent 5.02 percent of the Cook Inlet/Shelikof stock of approximately 22,900 animals. These take estimates represent small numbers relative to the affected species or stock sizes as shown in Table 8.

In addition to the quantitative methods used to estimate take, NMFS also considered qualitative factors that further support the “small numbers” determination, including: (1) The seasonal distribution and habitat use patterns of Cook Inlet beluga whales, which suggest that for much of the time only a small portion of the population would be accessible to impacts from EMALL's activity, as most animals are found in the Susitna Delta region of Upper Cook Inlet from early May through September; (2) other cetacean species are not common in the survey area; (3) the required mitigation requirements, which provide spatio-temporal limitations that avoid impacts to large numbers of belugas feeding and calving in the Susitna Delta; (4) the required monitoring requirements and mitigation measures described earlier in this document for all marine mammal species that will reduce the amount of takes; and (5) monitoring results from previous activities that indicated low numbers of beluga whale sightings within the Level B disturbance exclusion zone and low levels of Level B harassment takes of other marine mammals. Therefore, NMFS determined that the numbers of animals likely to be taken are small.

Impact on Availability of Affected Species for Taking for Subsistence Uses

Relevant Subsistence Uses

The subsistence harvest of marine mammals transcends the nutritional and economic values attributed to the animal and is an integral part of the cultural identity of the region's Alaska Native communities. Inedible parts of the whale provide Native artisans with materials for cultural handicrafts, and the hunting itself perpetuates Native traditions by transmitting traditional skills and knowledge to younger generations (NOAA, 2007).

The Cook Inlet beluga whale has traditionally been hunted by Alaska Natives for subsistence purposes. For several decades prior to the 1980s, the Native Village of Tyonek residents were the primary subsistence hunters of Cook Inlet beluga whales. During the 1980s and 1990s, Alaska Natives from villages in the western, northwestern, and North Slope regions of Alaska either moved to or visited the south central region and participated in the yearly subsistence harvest (Stanek, 1994). From 1994 to 1998, NMFS estimated 65 whales per year (range 21-123) were taken in this harvest, including those successfully taken for food and those struck and lost. NMFS concluded that this number was high enough to account for the estimated 14 percent annual decline in the population during this time (Hobbs et al., 2008). Actual mortality may have been higher, given the difficulty of estimating the number of whales struck and lost during the hunts. In 1999, a moratorium was enacted (Pub. L. 106-31) prohibiting the subsistence take of Cook Inlet beluga whales except through a cooperative agreement between NMFS and the affected Alaska Native organizations. Since the Cook Inlet beluga whale harvest was regulated in 1999 requiring cooperative agreements, five beluga whales have been struck and harvested. Those beluga whales were harvested in 2001 (one animal), 2002 (one animal), 2003 (one animal), and 2005 (two animals). The Native Village of Tyonek agreed not to hunt or request a hunt in 2007, when no co-management agreement was to be signed (NMFS, 2008a).

On October 15, 2008, NMFS published a final rule that established long-term harvest limits on Cook Inlet beluga whales that may be taken by Alaska Natives for subsistence purposes (73 FR 60976). That rule prohibits harvest for a 5-year interval period if the average stock abundance of Cook Inlet beluga whales over the prior five-year interval is below 350 whales. Harvest levels for the current 5-year planning interval (2013-2017) are zero because the average stock abundance for the previous five-year period (2008-2012) was below 350 whales. Based on the average abundance over the 2002-2007 period, no hunt occurred between 2008 and 2012 (NMFS, 2008a). The Cook Inlet Marine Mammal Council, which managed the Alaska Native Subsistence fishery with NMFS, was disbanded by a unanimous vote of the Tribes' representatives on June 20, 2012. At this time, no harvest is expected in 2015 or, likely, in 2016.

Data on the harvest of other marine mammals in Cook Inlet are lacking. Some data are available on the subsistence harvest of harbor seals, harbor porpoises, and killer whales in Alaska in the marine mammal stock assessments. However, these numbers are for the Gulf of Alaska including Cook Inlet, and they are not indicative of the harvest in Cook Inlet.

There is a low level of subsistence hunting for harbor seals in Cook Inlet. Seal hunting occurs opportunistically among Alaska Natives who may be fishing or travelling in the upper Inlet near the mouths of the Susitna River, Beluga River, and Little Susitna. Some detailed information on the subsistence harvest of harbor seals is available from past studies conducted by the Alaska Department of Fish & Game (Wolfe et al., 2009). In 2008, 33 harbor seals were taken for harvest in the Upper Kenai-Cook Inlet area. In the same study, reports from hunters stated that harbor seal populations in the area were increasing (28.6%) or remaining stable (71.4%). The specific hunting regions identified were Anchorage, Homer, Kenai, and Tyonek, and hunting generally peaks in March, September, and November (Wolfe et al., 2009).

Potential Impacts on Availability for Subsistence Uses

Section 101(a)(5)(D) also requires NMFS to determine that the taking will not have an unmitigable adverse effect on the availability of marine mammal species or stocks for subsistence use. NMFS has defined “unmitigable adverse impact” in 50 CFR 216.103 as an impact resulting from the specified activity: (1) That is likely to reduce the availability of the species to a level insufficient for a harvest to meet subsistence needs by: (i) Causing the marine mammals to abandon or avoid hunting areas; (ii) Directly displacing subsistence users; or (iii) Placing physical barriers between the marine mammals and the subsistence hunters; and (2) That cannot be sufficiently mitigated by other measures to increase the availability of marine mammals to allow subsistence needs to be met.

The primary concern is the disturbance of marine mammals through the introduction of anthropogenic sound into the marine environment during the proposed survey. Marine mammals could be behaviorally harassed and either become more difficult to hunt or temporarily abandon traditional hunting grounds. However, the proposed survey will not have any impacts to beluga harvests as none currently occur in Cook Inlet. Additionally, subsistence harvests of other marine mammal species are limited in Cook Inlet.

Plan of Cooperation or Measures To Minimize Impacts to Subsistence Hunts

The entire upper Cook unit and a portion of the lower Cook unit falls north of 60° N., or within the region NMFS has designated as an Arctic subsistence use area. EMALL provided detailed information in Section 8 of their application regarding their plan to cooperate with local subsistence users and stakeholders regarding the potential effects of their proposed activity. There are several villages in EMALL's proposed project area that have traditionally hunted marine mammals, primarily harbor seals. Tyonek is the only tribal village in upper Cook Inlet with a tradition of hunting marine mammals, in this case harbor seals and beluga whales. However, for either species the annual recorded harvest since the 1980s has averaged about one or fewer of either species (Fall et al. 1984, Wolfe et al. 2009, SRBA and HC 2011), and there is currently a moratorium on subsistence harvest of belugas. Further, many of the seals that are harvested are done incidentally to salmon fishing or moose hunting (Fall et al. 1984, Merrill and Orpheim 2013), often near the mouths of the Susitna Delta rivers (Fall et al. 1984) north of EMALL's proposed seismic survey area.

Villages in lower Cook Inlet adjacent to EMALL's proposed survey area (Kenai, Salamatof, and Nikiski) have either not traditionally hunted beluga whales, or at least not in recent years, and rarely do they harvest sea lions. These villages more commonly harvest harbor seals, with Kenai reporting an average of about 13 per year between 1992 and 2008 (Wolfe et al. 2009). According to Fall et al. (1984), many of the seals harvested by hunters from these villages were taken on the west side of the inlet during hunting excursions for moose and black bears.

Although marine mammals remain an important subsistence resource in Cook Inlet, the number of animals annually harvested is low, and are primarily harbor seals. Much of the harbor seal harvest occurs incidental to other fishing and hunting activities, and at areas outside of the EMALL's proposed survey areas such as the Susitna Delta or the west side of lower Cook Inlet. Also, EMALL is unlikely to conduct activity in the vicinity of any of the river mouths where large numbers of seals haul out.

EMALL and NMFS recognize the importance of ensuring that Alaska Natives and federally recognized tribes are informed, engaged, and involved during the permitting process and will continue to work with the Alaska Natives and tribes to discuss operations and activities.

Prior to offshore activities EMALL was to consult with nearby communities such as Tyonek, Salamatof, and the Kenaitze Indian Tribe to attend and present the program description prior to operations within those areas. These meetings were conducted and no issues related to subsistence use of marine mammals was raised.

If a conflict does occur with project activities involving subsistence or fishing, the project manager will immediately contact the affected party to resolve the conflict.

Unmitigable Adverse Impact Analysis and Determination

The project will not have any effect on beluga whale harvests because no beluga harvest will take place in 2015. Additionally, the proposed seismic survey area is not an important native subsistence site for other subsistence species of marine mammals thus, the number harvested is expected to be extremely low. The timing and location of subsistence harvest of Cook Inlet harbor seals may coincide with EMALL's project, but because this subsistence hunt is conducted opportunistically and at such a low level (NMFS, 2013c), EMALL's program is not expected to have an impact on the subsistence use of harbor seals. Moreover, the proposed survey would result in only temporary disturbances. Accordingly, the specified activity would not impact the availability of these other marine mammal species for subsistence uses.

NMFS anticipates that any effects from EMALL's proposed survey on marine mammals, especially harbor seals and Cook Inlet beluga whales, which are or have been taken for subsistence uses, would be short-term, site specific, and limited to inconsequential changes in behavior and mild stress responses. NMFS does not anticipate that the authorized taking of affected species or stocks will reduce the availability of the species to a level insufficient for a harvest to meet subsistence needs by: (1) Causing the marine mammals to abandon or avoid hunting areas; (2) directly displacing subsistence users; or (3) placing physical barriers between the marine mammals and the subsistence hunters; and that cannot be sufficiently mitigated by other measures to increase the availability of marine mammals to allow subsistence needs to be met. Based on the description of the specified activity, the measures described to minimize adverse effects on the availability of marine mammals for subsistence purposes, and the required mitigation and monitoring measures, NMFS has determined that there will not be an unmitigable adverse impact on subsistence uses from EMALL's proposed activities.

Endangered Species Act

There is one marine mammal species listed as endangered under the ESA with confirmed or possible occurrence in the project area: The Cook Inlet beluga whale. In addition, the action could occur within 10 miles of designated critical habitat for the Cook Inlet beluga whale. NMFS's Permits and Conservation Division has initiated consultation with NMFS' Alaska Region Protected Resources Division under section 7 of the ESA. This consultation concluded on August 13, 2015, when a Biological Opinion was issued. The Biological Opinion determined that the issuance of an IHA is not likely to jeapordize the continued existence of the Cook Inlet beluga whales or destroy or adversely modify Cook Inlet beluga whale critical habitat. Finally, the Alaska region issued an Incidental Take Statement (ITS) for Cook Inlet beluga whales. The ITS contains reasonable and prudent measures implemented by the terms and conditions to minimize the effect of this take.

National Environmental Policy Act

NMFS prepared an EA that includes an analysis of potential environmental effects associated with NMFS' issuance of an IHA to EMALL to take marine mammals incidental to conducting a geophysical and geotechnical survey program in Cook Inlet, Alaska. NMFS has finalized the EA and prepared a Finding of No Significant Impact for this action. Therefore, preparation of an Environmental Impact Statement is not necessary.

Authorization

As a result of these determinations, NMFS has issued an IHA to Exxon Mobil Alaska LNG LLC (EMALL) for taking marine mammals incidental to a geophysical and geotechnical survey in Cook Inlet, Alaska, provided the previously mentioned mitigation, monitoring, and reporting requirements are incorporated.

Dated: August 17, 2015.

Donna S. Wieting,

Director, Office of Protected Resources, National Marine Fisheries Service.