Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to Geophysical and Geotechnical Survey in Cook Inlet, Alaska, 6375-6404 [2016-01967]
Agencies
[Federal Register Volume 81, Number 24 (Friday, February 5, 2016)] [Notices] [Pages 6375-6404] From the Federal Register Online via the Government Publishing Office [www.gpo.gov] [FR Doc No: 2016-01967] [[Page 6375]] Vol. 81 Friday, No. 24 February 5, 2016 Part III Department of Commerce ----------------------------------------------------------------------- National Oceanic and Atmospheric Administration ----------------------------------------------------------------------- Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to Geophysical and Geotechnical Survey in Cook Inlet, Alaska; Notices Federal Register / Vol. 81 , No. 24 / Friday, February 5, 2016 / Notices [[Page 6376]] ----------------------------------------------------------------------- DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration RIN 0648-XE403 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; proposed incidental harassment authorization; request for comments. ----------------------------------------------------------------------- SUMMARY: NMFS has received an application from ExxonMobil Alaska LNG LLC (EMALL) for an Incidental Harassment Authorization (IHA) to take marine mammals, by harassment, incidental to a geophysical and geotechnical survey in Cook Inlet, Alaska. This action is proposed to occur for 16 weeks. Pursuant to the Marine Mammal Protection Act (MMPA), NMFS is requesting comments on its proposal to issue an IHA to EMALL to incidentally take, by Level B Harassment only, marine mammals during the specified activity. DATES: Comments and information must be received no later than March 7, 2016. ADDRESSES: Comments on the application should be addressed to Jolie Harrison, Chief, Permits and Conservation Division, Office of Protected Resources, National Marine Fisheries Service, 1315 East-West Highway, Silver Spring, MD 20910. The mailbox address for providing email comments is itp.young@noaa.gov. Comments sent via email, including all attachments, must not exceed a 25-megabyte file size. NMFS is not responsible for comments sent to addresses other than those provided here. Instructions: All comments received are a part of the public record and will generally be posted to https://www.nmfs.noaa.gov/pr/permits/incidental.htm without change. All Personal Identifying Information (for example, name, address, etc.) voluntarily submitted by the commenter may be publicly accessible. Do not submit Confidential Business Information or otherwise sensitive or protected information. An electronic copy of the application may be obtained by writing to the address specified above, telephoning the contact listed below (see FOR FURTHER INFORMATION CONTACT), or visiting the internet at: https://www.nmfs.noaa.gov/pr/permits/incidental.htm. The following associated documents are also available at the same internet address: Draft Environmental Assessment. FOR FURTHER INFORMATION CONTACT: Sara Young, Office of Protected Resources, NMFS, (301) 427-8484. 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 October 5, 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 December 22, 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 16 weeks during the 2016 open water season beginning on March 1, 2016. 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 a vibracore. Take, by Level B Harassment only, of individuals of four species of marine mammals is anticipated to result from the specified activities. EMALL received an Authorization for 2015 to conduct a similar suite of activities using the same technologies. The Authorization was issued for 84 days beginning August 14, 2015 (80 FR 50989). 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 in\3\) airgun array, 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 EMALL expects operations to occur 102 days during the 2016 open- water season between March 2016 and November 2016. Operations in the pipeline survey area would occur for approximately 46 days, and operations in the marine facilities survey area and [[Page 6377]] LNG carrier (LNGC) approach survey area would occur for a total of approximately 56 days. Approximately 100 km (62 mi) of transect line (the linear distance traveled by the survey vessel) would be surveyed on an average day. The use of an air gun from a stationary platform would occur over an estimated 24 days in the marine facilities survey area. Vibracoring would occur approximately 120 times (estimated 60 days) during the 2016 open-water season between March 2016 and November 2016. It is expected that on average, two vibracores would be conducted each day depending on tides and currents, with the sound source operating for a few minutes each time the equipment is deployed. The survey days may not be consecutive, given operational limitations including but not limited to tides, currents, hours of daylight, vessel resupply, personnel fatigue days, weather, and simultaneous operations. The activities would be scheduled in such a manner as to minimize potential effects to marine mammals, subsistence activities, and other users of the Cook Inlet. EMALL will engage with NMFS should the program require additional time to complete. Specified Geographic Region Three separate areas will be surveyed in Cook Inlet. The survey areas are shown in Figure 1 of the application. The survey areas were sized to provide siting flexibility for future infrastructure to avoid existing hazards. The pipeline survey area (Figure 2 in the application) extends in the marine waters of Cook Inlet from the northwest shoreline of Upper Cook Inlet near the communities of Tyonek and Beluga to the southeast shoreline of Upper Cook Inlet near Boulder Point on the Kenai Peninsula. This survey area is approximately 47 km (29 mi) in length and averages approximately 16 km (10 mi) wide. The pipeline survey area is 795 km\2\ (307 mi\2\). The marine facilities survey area and LNGC approach survey areas (Figure 3 in the application) are located in the marine waters of Cook Inlet near the eastern shoreline of what is defined as the northern region of Lower Cook Inlet, south of the Forelands and adjacent to Nikiski on the Kenai Peninsula. The marine facilities survey area encompasses 109 km\2\ (42 mi\2\) and the LNGC approach survey area encompasses 79 km\2\ (30 mi\2\). In the LNGC approach survey area, the chirp and boomer sub-bottom profilers will be operated simultaneously. The marine facilities survey area will be surveyed twice: Once with the chirp and boomer sub-bottom profilers operated simultaneously, and once with the air gun and chirp subbottom profiler operated simultaneously. The pipeline survey area will also be surveyed twice: Once with the chirp and boomer sub-bottom profilers operated simultaneously and once with the boomer sub-bottom profiler and air gun operated simultaneously. Use of an air gun from a stationary platform will be conducted only in the marine facilities survey area. Vibracoring may be conducted throughout all of the survey areas. Detailed Description of Activities The details of this activity are broken down into two categories for further description and analysis: Geophysical surveys and geotechnical surveys. Geophysical Surveys The types of acoustical geophysical equipment planned for use in the Cook Inlet 2016 G&G Program are indicated in Table 1 in the application. The equipment includes: Sub-bottom profilers (chirp and boomer), 0.983 L (60 in\3\) airgun, and vibracore. Downhole geophysics is included in the table as a sound source, but is not considered further in this assessment as the energy source will not generate significant sound energy within the water column since the equipment will be located downhole within the geotechnical boreholes. The transmitter (source) and receiver are both housed within the same probe or tool that is lowered into the hole on a wireline. The suspension log transmitter is an electromechanical device. It consists of a metallic barrel (the hammer) disposed horizontally in the tool and actuated by an electromagnet (solenoid) to hit the inside of tool body (the plate). The fundamental H1 mode is at about 4.5 KHz, and H2 is at 9 KHz. An extra resonance (unknown) mode is also present at about 15 Khz. An analysis performed to estimate the expected sound level of the proposed borehole logging equipment scaled the sound produced by a steel pile driven by a hammer (given that both are cylindrical noise sources and produce impulsive sounds) and concluded that the sound level produced at 25 m by the borehole logging equipment would be less than 142 dB. This is not considering the confining effect of the borehole which would lower the sound level even further (I&R, 2015). The other types of geophysical equipment proposed for the 2015 program will generate impulsive sound in the water column and are described below Information on the acoustic characteristics of geophysical and geotechnical sound sources is also summarized in Table 2 in the application, followed by a corresponding description of each piece of equipment to be used. Sub-Bottom Profiler--Chirp The chirp sub-bottom profiler planned for use in this program is a precisely controlled ``chirp'' system that emits high-energy sounds with a resolution of one millisecond (ms) and is used to penetrate and profile the shallow sediments near the sea floor. At operating frequencies of 2 to 16 kHz (Table 2 in application), this system will be operating at the lower end of the hearing range of beluga whales and well below the most sensitive hearing range of beluga whales (45-80 kHz, Castellote et al. 2014), killer whales (18-42 kHz; Szymanski et al. 1999) and harbor porpoises (16-140 kHz; Kastelein et al. 2002). The source level is estimated at 202 dB re 1 [mu]Pa-m (rms). The beam width is 24 degrees and pointed downward. The chirp will be used in combination with the boomer, and separately in combination with the air gun. Sub-Bottom Profiler--Boomer A boomer sub-bottom profiling system with a penetration depth of up to 600 ms and resolution of 2 to 10 ms will be used to penetrate and profile the Cook Inlet sediments to an intermediate depth. The system will be towed behind the vessel. With a sound energy source level of about 205 dB re 1 [mu]Pa-m (rms) at frequencies of 0.5 to 6 kHz (Table 2 in application), most of the sound energy generated by the boomer will be at frequencies that are well below peak hearing sensitivities of beluga whales (45-80 kHz; Castellote et al. 2014), but would still be detectable by these animals. The boomer is pointed downward but the equipment is omni-directional so the physical orientation is irrelevant. Airgun A 0.983 L (60 in\3\) airgun or airgun array of equal or lesser volume will be used to gather high resolution profiling at greater depths below the seafloor. The published source level from Sercel (the manufacturer) for a 0.983 L (60 in\3\) airgun is 216 dB re 1 [mu]Pa-m (equating to about 206 dB re 1 [mu]Pa-m (rms). These airguns typically produce sound levels at frequencies of less than 1 kHz (Richardson et al. 1995, Zykov and Carr 2012), or below the most sensitive hearing of beluga whales (45-80 kHz; Castellote et al. 2014), but within the [[Page 6378]] functional hearing of these animals (>75 Hz; Southall et al. 2007). The airgun will only be used during geophysical surveys conducted in the Marine Facilities area (Lower Inlet). Geotechnical Surveys Shallow Geotechnical Investigations--Vibracores Vibracoring is conducted to obtain cores of the seafloor sediment from the surface down to a depth of about 6.1 m (20 ft). The cores are later analyzed in the laboratory for moisture, organic and carbonate content, shear strength, and grain size. Vibracore samplers consist of a 10-cm (4.0-in) diameter core barrel and a vibratory driving mechanism mounted on a four-legged frame, which is lowered to the seafloor. The electric motor driving mechanism oscillates the core barrel into the sediment where a core sample is then extracted. The duration of the operation varies with substrate type, but generally the sound source (driving mechanism) is operable for only the one or two minutes it takes to complete the 6.1-m (20-ft) bore and the entire setup process often takes less than one hour. 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 187.4 dB re 1 [mu]Pa-m (rms), with a frequency range of between 10 Hz and 20 kHz (Table 2). Vibracoring will result in the largest zone of influence (ZOI; area ensonified by sound energy greater than the 120 dB threshold) among the continuous sound sources. Vibracoring would also have a very small effect on the benthic habitat. Vibracoring will be conducted approximately 120 times over 60 days. Because of the very brief duration within a day (each event lasting 1 or 2-minute periods) of this continuous, non-impulsive sound, combined with the small number of days the source will be used overall, NMFS does not believe that the vibracore operations will result in the take of marine mammals. However, because the applicant requested take from this source and included a quantitative analysis in their application, that analysis will be included here for reference and opportunity for public comment. Vessels Vessels used in the program will be approximately 15-42 m (50-140 ft) in length and 4.5-15 m (15-50 ft) in width (beam) with approximately 750-1500 horsepower. When used in combination, the air gun and chirp and boomer sub-bottom profilers will typically be deployed from the same survey vessel. Vibracoring may be conducted from a separate survey vessel. The air gun may also be used from a stationary platform or barge. 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 found in Upper Cook Inlet is detailed in Table 1 below. Table 1--Marine Mammals Inhabiting the Cook Inlet Action Area ---------------------------------------------------------------------------------------------------------------- Stock abundance Relative ESA/MMPA (CV, Nmin, most occurrence in Cook Species Stock status\1\; recent abundance Inlet; season of strategic (Y/N) survey) \2\ occurrence ---------------------------------------------------------------------------------------------------------------- Killer whale.................... Alaska Resident... -;N............... 2,347 (N/A; 2,084; Occasionally Alaska Transient.. -:N............... 2009). sighted in Lower 345 (N/A; 303; Cook Inlet. 2003). Beluga whale.................... Cook Inlet........ E/D;Y............. 312 (0.10; 280; Use upper Inlet in 2012). summer and lower in winter: Annual. Harbor porpoise................. Gulf of Alaska.... -;Y............... 31,046 (0.214; Widespread in the 25,987; 1998). Inlet: Annual (less in winter). Harbor seal..................... Cook Inlet/ -;N............... 22,900 (0.053; Frequently found Shelikof. 21,896; 2006). in upper and lower inlet; annual (more in northern Inlet in summer). ---------------------------------------------------------------------------------------------------------------- \1\ ESA status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-) indicates that the species is not listed under the ESA or designated as depleted under the MMPA. Under the MMPA, a strategic stock is one for which the level of direct human-caused mortality exceeds PBR (see footnote 3) or which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed under the ESA is automatically designated under the MMPA as depleted and as a strategic stock. \2\ CV is coefficient of variation; Nmin is the minimum estimate of stock abundance. In some cases, CV is not applicable. For certain stocks, abundance estimates are actual counts of animals and there is no associated CV. The most recent abundance survey that is reflected in the abundance estimate is presented; there may be more recent surveys that have not yet been incorporated into the estimate. 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), [[Page 6379]] 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 4 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, [[Page 6380]] 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[deg]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 [[Page 6381]] 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 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 [[Page 6382]] 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 in\3\ or 3,147 in\3\ 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 [mu]Pa 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 [mu]Pa (Bain and Williams, 2006) and Dall's porpoises occupied and tolerated areas receiving exposures of 170-180 dB re: 1 [mu]Pa (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 [mu]Pa (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 [[Page 6383]] 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 [[Page 6384]] 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 f
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