Takes of Marine Mammals Incidental to Specified Activities; Marine Geophysical Survey in the Eastern Mediterranean Sea, November to December, 2015

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 the Lamont-Doherty Earth Observatory (Lamont-Doherty) in collaboration with the National Science Foundation (NSF), for an Incidental Harassment Authorization (Authorization) to take marine mammals, by harassment only, incidental to conducting a marine geophysical (seismic) survey in the eastern Mediterranean Sea, mid-November through December, 2015. The proposed dates for this action would be mid-November 2015 through December 31, 2015, to account for minor deviations due to logistics and weather. Per the Marine Mammal Protection Act, we are requesting comments on our proposal to issue an Authorization to Lamont-Doherty to incidentally take, by Level B harassment, of 22 species of marine mammals during the specified activity and to incidentally take by Level A harassment, of four species of marine mammals. Although considered unlikely, any Level A harassment potentially incurred would be expected to be in the form of some smaller degree of permanent hearing loss due in part to the required monitoring measures for detecting marine mammals and required mitigation measures for power downs or shut downs of the airgun array if any animal is likely to enter the Level A exclusion zone. Neither mortality nor complete deafness of marine mammals are expected to result from this survey.

DATES:

NMFS must receive comments and information on or before October 4, 2015.

ADDRESSES:

Address comments on the application 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.Cody@noaa.gov. Please include 0648-XE125 in the subject line. Comments sent via email to ITP.Cody@noaa.gov, including all attachments, must not exceed a 25-megabyte file size. NMFS is not responsible for email comments sent to addresses other than the one provided here.

Instructions: All submitted comments are a part of the public record, and NMFS will post them to http://www.nmfs.noaa.gov/pr/permits/incidental/research.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.

To obtain an electronic copy of the application containing a list of the references used in this document, write to the previously mentioned address, telephone the contact listed here (see FOR FURTHER INFORMATION CONTACT), or visit the internet at: http://www.nmfs.noaa.gov/pr/permits/incidental/research.htm .

NSF has prepared a draft Environmental Analysis in accordance with Executive Order 12114, “Environmental Effects Abroad of Major Federal Actions” for their proposed federal action. The draft environmental analysis titled “Draft Environmental Analysis of a Marine Geophysical Survey by the R/V Marcus G. Langseth in the Eastern Mediterranean Sea, November-December 2015,” prepared by LGL, Ltd. environmental research associates, on behalf of NSF and Lamont-Doherty is available at the same internet address. Information in the Lamont-Doherty's application, NSF's draft environmental analysis, and this notice collectively provide the environmental information related to the proposed issuance of the Authorization for public review and comment.

FOR FURTHER INFORMATION CONTACT:

Jeannine Cody, NMFS, Office of Protected Resources, NMFS (301) 427-8401.

SUPPLEMENTARY INFORMATION:

Background

Section 101(a)(5)(D) of the Marine Mammal Protection Act of 1972, as amended (MMPA; 16 U.S.C. 1361 et seq.) directs the Secretary of Commerce to allow, upon request, the incidental, but not intentional, taking of small numbers of marine mammals of a species or population stock, by U.S. citizens who engage in a specified activity (other than commercial fishing) within a specified geographical region if, after NMFS provides a notice of a proposed authorization to the public for review and comment: (1) NMFS makes certain findings; and (2) the taking is limited to harassment.

An Authorization shall be granted for the incidental taking of small numbers of marine mammals if NMFS finds that the taking will have a negligible impact on the species or stock(s), and will not have an unmitigable adverse impact on the availability of the species or stock(s) for subsistence uses (where relevant). The Authorization must also set forth the permissible methods of taking; other means of effecting the least practicable adverse impact on the species or stock and its habitat (i.e., mitigation); and requirements pertaining to the monitoring and reporting of such taking. 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 April 20, 2015, NMFS received an application from Lamont-Doherty requesting that NMFS issue an Authorization for the take of marine mammals, incidental to the University of Oregon conducting a seismic survey in the eastern Mediterranean Sea October through November 2015. Following the initial application submission, Lamont-Doherty submitted a revised application with new dates for the proposed survey (approximately mid-November through December, 2015). NMFS considered the revised application adequate and complete on August 25, 2015.

The proposed survey would take place partially within Greece's territorial seas (less than 6 nautical miles (nmi) [11 km; 7 mi] from the shore) and partially in the high seas. However, NMFS cannot authorize the incidental take of marine mammals in the territorial seas of foreign nations, as the MMPA does not apply in those waters. However, NMFS still needs to calculate the level of incidental take in the entire activity area (territorial seas and high seas) as part of the analysis supporting our preliminary determination under the MMPA that the activity will have a negligible impact on the affected species.

Lamont-Doherty proposes to conduct a high-energy, seismic survey on theR/V Marcus G. Langseth (Langseth), a vessel owned by NSF and operated on its behalf by Columbia University's Lamont-Doherty in the eastern Mediterranean Sea for approximately 16 days from approximately mid-November 2015, through mid-December 2015. The following specific aspect of the proposed activity has the potential to take marine mammals: Increased underwater sound generated during the operation of the seismic airgun arrays. We anticipate that take, by Level B harassment, of 22 species of marine mammals could result from the specified activity. Although the unlikely, NMFS also anticipates that a small level of take by Level A harassment of four species of marine mammals could occur during the proposed survey.

Description of the Specified Activity

Overview

Lamont-Doherty plans to use one source vessel, the Langseth, an array of 36 airguns as the energy source, a receiving system of 93 ocean bottom seismometers (OBSs) for the northern portion of the proposed survey and a single 8-kilometer (km) hydrophone streamer for the southern portion of the proposed survey. In addition to the operations of the airguns, Lamont-Doherty intends to operate a multibeam echosounder and a sub-bottom profiler on the Langseth continuously throughout the proposed survey. However, Lamont-Doherty will not operate the multibeam echosounder and sub-bottom profiler during transits to and from the survey areas (i.e., when the airguns are not operating).

The purpose of the survey is to collect and analyze seismic refraction data on and around the island of Santorini (Thira) to examine the crustal magma plumbing of the Santorini volcanic system. NMFS refers the public to Lamont-Doherty's application (see page 2) for more detailed information on the proposed research objectives.

Dates and Duration

Lamont-Doherty proposes to conduct the seismic survey for approximately 30 days which includes approximately 16 days of seismic surveying, 11 days for OBS deployment/retrieval, and 1 day of hydrophone streamer deployment. The proposed study (e.g., equipment testing, startup, line changes, repeat coverage of any areas, and equipment recovery) would include approximately 384 hours of airgun operations (i.e., 16 days over 24 hours). Some minor deviation from Lamont-Doherty's requested dates of mid-November through December 2015 is possible, depending on logistics, weather conditions, and the need to repeat some lines if data quality is substandard. Thus, the proposed Authorization, if issued, would be effective from mid-November through December 31, 2015.

NMFS refers the reader to the Detailed Description of Activities section later in this notice for more information on the scope of the proposed activities.

Specified Geographic Region

Lamont-Doherty proposes to conduct one portion of the proposed seismic survey in the Aegean Sea, located approximately between 36.1-36.8° N. and 24.7-26.1° E. in the eastern Mediterranean Sea (see Figure 1). Water depths in the Aegean Sea survey area are approximately 20 to 500 meters (m) (66 to 1,640 feet (ft)). Lamont-Doherty would conduct the second portion of the proposed seismic survey over the Hellenic subduction zone which starts in the Aegean Sea at approximately 36.4° N., 23.9° E. and runs to the southwest, ending at approximately 34.9° N., 22.6° E. Water depths in that area range from 1,000 to 3,000 m (3,280 to 9,843 ft). Lamont-Doherty would conduct the proposed seismic survey within the Exclusive Economic Zone (EEZ) and territorial waters of Greece. Greece's territorial seas extend out to six nautical miles (nmi) (7 miles [mi]; 11 kilometers [km]).

Principal and Collaborating Investigators

The proposed survey's principal investigators are Drs. E. Hooft and D. Toomey (University of Oregon). The Santorini portion of the study also involves international collaboration with Dr. P. Nomikou (University of Athens) who would be on board during the entire seismic survey.

Detailed Description of the Specified Activities

Transit Activities

The Langseth would depart from New York, NY, and transit for approximately three weeks to Greece. The Langseth would depart from Piraieus, Greece in mid-November 2015 and spend one day in transit to the proposed survey areas. At the conclusion of the survey, the Langseth would arrive at Iraklio, Crete. Some minor deviation from these dates is possible, depending on logistics and weather.

Vessel Specifications

The survey would involve one source vessel, the R/V Langseth. The Langseth, owned by the Foundation and operated by Lamont-Doherty, is a seismic research vessel with a quiet propulsion system that avoids interference with the seismic signals emanating from the airgun array. The vessel is 71.5 m (235 ft) long; has a beam of 17.0 m (56 ft); a maximum draft of 5.9 m (19 ft); and a gross tonnage of 3,834 pounds. It has two 3,550 horsepower (hp) BergenBRG-6 diesel engines which drive two propellers. Each propeller has four blades and the shaft typically rotates at 750 revolutions per minute. The vessel also has an 800-hp bowthruster, which is off during seismic acquisition.

The Langseth's speed during seismic operations would be approximately 4.5 knots (kt) (8.3 km/hour (hr); 5.1 miles per hour (mph)). The vessel's cruising speed outside of seismic operations is approximately 10 kt (18.5 km/hr; 11.5 mph). While the Langseth tows the airgun array, its turning rate is limited to five degrees per minute. Thus, the Langseth's maneuverability is limited during operations while it tows the streamers.

The vessel also has an observation tower from which protected species visual observers (observers) would watch for marine mammals before and during the proposed seismic acquisition operations. When stationed on the observation platform, the observer's eye level will be approximately 21.5 m (71 ft) above sea level providing the observer an unobstructed view around the entire vessel.

Data Acquisition Activities

The proposed survey would cover a total of approximately 2,140 km (1,330 mi) of transect lines (1,936 km [1,203 mi] of transect lines for the Aegean Sea leg plus approximately 204 km [127 mi] of transect lines for the Hellenic subduction zone leg). For the Aegean Sea leg portion of the proposed survey, the parallel transect lines have a spacing interval that ranges from 1.4 to 4.5 km (0.9 to 2.8 mi). The Hellenic subduction zone leg of the proposed survey is one continuous transect line with no transect line overlap.

During the survey, the Langseth would deploy 36 airguns as an energy source with a total volume of 6,600 cubic inches (in³). The receiving system would consist of 93 OBSs for the Aegean Sea leg of the proposed survey and a single 8-km (5-mi) hydrophone streamer for the Hellenic subduction zone leg of the proposed survey. As the Langseth tows the airgun array along the survey lines, the OBSs and hydrophone streamer would receive the returning acoustic signals and transfer the data to the on-board processing system.

Seismic Airguns

The airguns are a mixture of Bolt 1500LL and Bolt 1900LLX airguns ranging in size from 40 to 220 in³, with a firing pressure of 1,950 pounds per square inch. The dominant frequency components range from zero to 188 Hertz (Hz).

During the survey, Lamont-Doherty would plan to use the full array with most of the airguns in inactive mode. The Langseth would tow the array at a depth of either 9 or 12 m (29.5 or 39.4 ft) resulting in a shot interval range of approximately 35 to 170 seconds (s) (approximately 80 to 390 m; 262 to 1,280 ft) for the Aegean Sea leg and a shot interval of approximately 22 s (50 m; 164 ft) for the Hellenic subduction zone leg of the proposed survey. During acquisition the airguns will emit a brief (approximately 0.1 s) pulse of sound. During the intervening periods of operations, the airguns are silent.

Airguns function by venting high-pressure air into the water which creates an air bubble. The pressure signature of an individual airgun consists of a sharp rise and then fall in pressure, followed by several positive and negative pressure excursions caused by the oscillation of the resulting air bubble. The oscillation of the air bubble transmits sounds downward through the seafloor, and there is also a reduction in the amount of sound transmitted in the near horizontal direction. The airgun array also emits sounds that travel horizontally toward non-target areas.

The nominal source levels of the airgun subarrays on the Langseth range from 240 to 247 decibels (dB) re: 1 µPa (peak to peak). (We express sound pressure level as the ratio of a measured sound pressure and a reference pressure level. The commonly used unit for sound pressure is dB and the commonly used reference pressure level in underwater acoustics is 1 microPascal (µPa)). Briefly, the effective source levels for horizontal propagation are lower than source levels for downward propagation. We refer the reader to Lamont-Doherty's Authorization application and NSF's Environmental Analysis for additional information on downward and horizontal sound propagation related to the airgun's source levels.

Additional Acoustic Data Acquisition Systems

Multibeam Echosounder: The Langseth will operate a Kongsberg EM 122 multibeam echosounder concurrently during airgun operations to map characteristics of the ocean floor. However, as stated earlier, Lamont-Doherty will not operate the multibeam echosounder during transits to and from the survey areas (i.e., when the airguns are not operating).

The hull-mounted echosounder emits brief pulses of sound (also called a ping) (10.5 to 13.0 kHz) in a fan-shaped beam that extends downward and to the sides of the ship. The transmitting beamwidth is 1 or 2° fore-aft and 150° athwartship and the maximum source level is 242 dB re: 1 μPa.

Each ping consists of eight (in water greater than 1,000 m; 3,280 ft) or four (in water less than 1,000 m; 3,280 ft) successive, fan-shaped transmissions, from two to 15 milliseconds (ms) in duration and each ensonifying a sector that extends 1° fore-aft. Continuous wave pulses increase from 2 to 15 ms long in water depths up to 2,600 m (8,530 ft). The echosounder uses frequency-modulated chirp pulses up to 100-ms long in water greater than 2,600 m (8,530 ft). The successive transmissions span an overall cross-track angular extent of about 150°, with 2-ms gaps between the pulses for successive sectors.

Sub-bottom Profiler: The Langseth will also operate a Knudsen Chirp 3260 sub-bottom profiler concurrently during airgun and echosounder operations to provide information about the sedimentary features and bottom topography. As with the case of the echosounder, Lamont-Doherty will not operate the sub-bottom profiler during transits to and from the survey areas (i.e., when the airguns are not operating).

The profiler is capable of reaching depths of 10,000 m (6.2 mi). The dominant frequency component is 3.5 kHz and a hull-mounted transducer on the vessel directs the beam downward in a 27° cone. The power output is 10 kilowatts (kW), but the actual maximum radiated power is three kilowatts or 222 dB re: 1 µPa. The ping duration is up to 64 ms with a pulse interval of one second, but a common mode of operation is to broadcast five pulses at 1-s intervals followed by a 5-s pause.

Ocean Bottom Seismometers: The Langseth would deploy a total of 93 OBSs on the sea floor at the beginning of the proposed survey in the Aegean Sea and then recover the instruments at the conclusion of the proposed survey.

Each seismometer is approximately 0.9 m (2.9 ft) high with a maximum diameter of 97 centimeters (cm) (3.1 ft). An anchor, made of a rolled steel bar grate which measures approximately 7 by 91 by 91.5 cm (3 by 36 by 36 inches) and weighs 45 kilograms (99 pounds) would anchor the seismometer to the seafloor.

After the Langseth completes the proposed seismic survey, an acoustic signal would trigger the release of each of the 46 seismometers from the ocean floor. The Langseth's acoustic release transponder, located on the vessel, communicates with the seismometer at a frequency of 9 to13 kilohertz (kHz). The maximum source level of the release signal is 242 dB re: 1 μPa with an 8-millisecond pulse length. The received signal activates the seismometer's double burn-wire release assembly which then releases the seismometer from the anchor. The seismometer then floats to the ocean surface for retrieval by the Langseth. The steel grate anchors from each of the seismometers would remain on the seafloor.

The Langseth crew would deploy the seismometers one-by-one from the stern of the vessel while onboard protected species observers will alert them to the presence of marine mammals and recommend ceasing deploying or recovering the seismometers to avoid potential entanglement with marine mammal.

Description of Marine Mammals in the Area of the Specified Activity

Table 1 in this notice provides the following: All marine mammal species with possible or confirmed occurrence in the proposed activity area; information on those species' regulatory status under the MMPA and the Endangered Species Act of 1973 (16 U.S.C. 1531 et seq.); abundance; occurrence and seasonality in the proposed activity area.

Lamont-Doherty presented species information in Table 2 of their application but excluded information for certain pinniped and cetacean species because they anticipated that these species would have a low likelihood of occurring in the survey area. Based on the best available information, NMFS expects that there may be a potential for certain cetacean and pinniped species to occur within the survey area (i.e., potentially be taken) and have included additional information for these species in Table 1 of this notice. NMFS will carry forward analyses on the species listed in Table 1 later in this document.

NMFS refers the public to Lamont-Doherty's application, NSF's draft environmental analysis (see ADDRESSES), NOAA Technical Memorandum NMFS-NE-228, U.S. Atlantic and Gulf of Mexico Marine Mammal Stock Assessments—2013 (Waring et al., 2014); and the Draft 2014 U.S. Atlantic and Gulf of Mexico Marine Mammal Stock Assessments (in review, 2015) available online at: http://www.nmfs.noaa.gov/pr/sars/species.htm for further information on the biology and local distribution of these species.

Potential Effects of the Specified Activities on Marine Mammals

This section includes a summary and discussion of the ways that components (e.g., seismic airgun operations, vessel movement) 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 “Proposed 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 Lamont-Doherty's activities in this section. This section does not consider the specific manner in which Lamont-Doherty would carry out the proposed activity, what mitigation measures Lamont-Doherty would implement, and how either of those would shape the anticipated impacts from this specific activity. Operating active acoustic sources, such as airgun arrays, has the potential for adverse effects on marine mammals. The majority of anticipated impacts would be from the use of the airgun array.

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 applicable to this proposed survey 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, 33 marine mammal species (6 mysticetes, 24 odontocetes, and 3 pinnipeds) would likely occur in the proposed action area. Table 2 presents the classification of these 33 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.

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 in³) on six species in shallow waters off British Columbia and Washington: Harbor seal, California sea lion (Zalophus californianus), Steller sea lion (Eumetopias jubatus), gray whale (Eschrichtius robustus), Dall's porpoise (Phocoenoides dalli), 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.

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., Richardson et al., 1986; 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 ceasing 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; Wartzok et al., 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).

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). 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).

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 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).

Blue Whales

McDonald et al. (1995) tracked blue whales relative to a seismic survey with a 1,600 in³ airgun array. One whale started its call sequence within 15 km (9.3 mi) from the source, then followed a pursuit track that decreased its distance to the vessel where it stopped calling at a range of 10 km (6.2 mi) (estimated received level at 143 dB re: 1 μPa (peak-to-peak)). After that point, the ship increased its distance from the whale which continued a new call sequence after approximately one hour and 10 km (6.2 mi) from the ship. The authors reported that the whale had taken a track paralleling the ship during the cessation phase but observed the whale moving diagonally away from the ship after approximately 30 minutes continuing to vocalize. Because the whale may have approached the ship intentionally or perhaps was unaffected by the airguns, the authors concluded that there was insufficient data to infer conclusions from their study related to blue whale responses (McDonald, et al., 1995).

Dunn and Hernandez (2009) tracked blue whales in the eastern tropical Pacific Ocean near the northern East Pacific Rise using 25 ocean-bottom-mounted hydrophones and ocean bottom seismometers during the conduct of an academic seismic survey by the R/V Maurice Ewing in 1997. During the airgun operations, the authors recorded the airgun pulses across the entire seismic array which they determined were detectable by eight whales that had entered into the area during a period of airgun activity (Dunn and Hernandez, 2009). The authors were able to track each whale call-by-call using the B components of the calls and examine the whales' locations and call characteristics with respect to the periods of airgun activity. The authors tracked the blue whales from 28 to 100 km (17 to 62 mi) away from active air-gun operations, but did not observe changes in call rates and found no evidence of anomalous behavior that they could directly ascribed to the use of the airguns (Dunn and Hernandez, 2009; Wilcock et al., 2014). Further, the authors state that while the data do not permit a thorough investigation of behavioral responses, they observed no correlation in vocalization or movement with the concurrent airgun activity and estimated that the sound levels produced by the Ewing's airguns and were approximately less than 145 dB re: 1 μPa (Dunn and Hernandez, 2009).

Fin Whales

Castellote et al. (2010) observed localized avoidance by fin whales during seismic airgun events in the western Mediterranean Sea and adjacent Atlantic waters from 2006-2009 and reported that singing fin whales moved away from an operating airgun array for a time period that extended beyond the duration of the airgun activity.

Gray Whales

A few studies have documented reactions of migrating and feeding (but not wintering) gray whales (Eschrichtius robustus) to seismic surveys. Malme et al. (1986, 1988) studied the responses of feeding eastern Pacific gray whales to pulses from a single 100-in³ airgun off St. Lawrence Island in the northern Bering Sea. They estimated, based on small sample sizes, that 50 percent of feeding gray whales stopped feeding at an average received pressure level of 173 dB re: 1 μPa on an (approximate) root mean square basis, and that 10 percent of feeding whales interrupted feeding at received levels of 163 dB re: 1 µPa. Those findings were generally consistent with the results of experiments conducted on larger numbers of gray whales that were migrating along the California coast (Malme et al., 1984; Malme and Miles, 1985), and western Pacific gray whales feeding off Sakhalin Island, Russia (Wursig et al., 1999; Gailey et al., 2007; Johnson et al., 2007; Yazvenko et al., 2007a, 2007b), along with data on gray whales off British Columbia (Bain and Williams, 2006).

Data on short-term reactions by cetaceans to impulsive noises are not necessarily indicative of long-term or biologically significant effects. It is not known whether impulsive sounds affect reproductive rate or distribution and habitat use in subsequent days or years. However, gray whales have continued to migrate annually along the west coast of North America with substantial increases in the population over recent years, despite intermittent seismic exploration (and much ship traffic) in that area for decades (Appendix A in Malme et al., 1984; Richardson et al., 1995; Allen and Angliss, 2014). The western Pacific gray whale population did not appear affected by a seismic survey in its feeding ground during a previous year (Johnson et al., 2007). Similarly, bowhead whales (Balaena mysticetus) have continued to travel to the eastern Beaufort Sea each summer, and their numbers have increased notably, despite seismic exploration in their summer and autumn range for many years (Richardson et al., 1987; Allen and Angliss, 2014). The history of coexistence between seismic surveys and baleen whales suggests that brief exposures to sound pulses from any single seismic survey are unlikely to result in prolonged effects.

Humpback Whales

McCauley et al. (1998, 2000) studied the responses of humpback whales off western Australia to a full-scale seismic survey with a 16-airgun array (2,678-in³) and to a single, 20-in³ airgun with source level of 227 dB re: 1 µPa (peak-to-peak). In the 1998 study, the researchers documented that avoidance reactions began at five to eight km (3.1 to 4.9 mi) from the array, and that those reactions kept most pods approximately three to four km (1.9 to 2.5 mi) from the operating seismic boat. In the 2000 study, McCauley et al. noted localized displacement during migration of four to five km (2.5 to 3.1 mi) by traveling pods and seven to 12 km (4.3 to 7.5 mi) by more sensitive resting pods of cow-calf pairs. Avoidance distances with respect to the single airgun were smaller but consistent with the results from the full array in terms of the received sound levels. The mean received level for initial avoidance of an approaching airgun was 140 dB re: 1 µPa for humpback pods containing females, and at the mean closest point of approach distance, the received level was 143 dB re: 1 µPa. The initial avoidance response generally occurred at distances of five to eight km (3.1 to 4.9 mi) from the airgun array and 2 km (1.2 mi) from the single airgun. However, some individual humpback whales, especially males, approached within distances of 100 to 400 m (328 to 1,312 ft), where the maximum received level was 179 dB re: 1 µPa.

Data collected by observers during several of Lamont-Doherty's seismic surveys in the northwest Atlantic Ocean showed that sighting rates of humpback whales were significantly greater during non-seismic periods compared with periods when a full array was operating (Moulton and Holst, 2010). In addition, humpback whales were more likely to swim away and less likely to swim towards a vessel during seismic versus non-seismic periods (Moulton and Holst, 2010).

Humpback whales on their summer feeding grounds in southeast Alaska did not exhibit persistent avoidance when exposed to seismic pulses from a 1.64-L (100-in³) airgun (Malme et al., 1985). Some humpbacks seemed “startled” at received levels of 150 to 169 dB re: 1 μPa. Malme et al. (1985) concluded that there was no clear evidence of avoidance, despite the possibility of subtle effects, at received levels up to 172 re: 1 μPa. However, Moulton and Holst (2010) reported that humpback whales monitored during seismic surveys in the northwest Atlantic had lower sighting rates and were most often seen swimming away from the vessel during seismic periods compared with periods when airguns were silent.

Other studies have suggested that south Atlantic humpback whales wintering off Brazil may be displaced or even strand upon exposure to seismic surveys (Engel et al., 2004). However, the evidence for this was circumstantial and subject to alternative explanations (IAGC, 2004). Also, the evidence was not consistent with subsequent results from the same area of Brazil (Parente et al., 2006), or with direct studies of humpbacks exposed to seismic surveys in other areas and seasons. After allowance for data from subsequent years, there was “no observable direct correlation” between strandings and seismic surveys (IWC, 2007: 236).

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 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.

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, Barry et al., 2010; 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.

Killer Whales

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).

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).

Sperm Whales

Most studies of sperm whales exposed to airgun sounds indicate that the whale shows considerable tolerance of airgun pulses (e.g., Stone, 2003; Moulton et al., 2005, 2006a; Stone and Tasker, 2006; Weir, 2008). In most cases the whales do not show strong avoidance, and they continue to call. However, controlled exposure experiments in the Gulf of Mexico indicate alteration of foraging behavior upon exposure to airgun sounds (Jochens et al., 2008; Miller et al., 2009; Tyack, 2009).

Beaked Whales

There are almost no specific data on the behavioral reactions of beaked whales to seismic surveys. Most beaked whales tend to avoid approaching vessels of other types (e.g., Wursig et al., 1998). They may also dive for an extended period when approached by a vessel (e.g., Kasuya, 1986), although it is uncertain how much longer such dives may be as compared to dives by undisturbed beaked whales, which also are often quite long (Baird et al., 2006; Tyack et al., 2006).

Based on a single observation, Aguilar-Soto et al. (2006) suggested a reduction in foraging efficiency of Cuvier's beaked whales during a close approach by a vessel. In contrast, Moulton and Holst (2010) reported 15 sightings of beaked whales during seismic studies in the northwest Atlantic and the authors observed seven of those sightings during times when at least one airgun was operating. Because sighting rates and distances were similar during seismic and non-seismic periods, the authors could not correlate changes to beaked whale behavior to the effects of airgun operations (Moulton and Holst, 2010).

Similarly, other studies have observed northern bottlenose whales remain in the general area of active seismic operations while continuing to produce high-frequency clicks when exposed to sound pulses from distant seismic surveys (Gosselin and Lawson, 2004; Laurinolli and Cochrane, 2005; Simard et al., 2005).

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 in³. 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 the proposed seismic survey, NMFS does not expect that animals would experience levels high enough or durations long enough to result in PTS.

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, 2002b, 2003, 2005a, 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 proposed seismic survey. 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 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. 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. Therefore, it is unlikely that such effects would occur given the brief duration of exposure during the proposed 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).

2. Potential Effects of Other Acoustic Devices

Multibeam Echosounder: Lamont-Doherty would operate the Kongsberg EM 122 multibeam echosounder from the source vessel during the planned survey. Sounds from the multibeam echosounder are very short pulses, occurring for two to 15 ms once every five to 20 s, depending on water depth. Most of the energy in the sound pulses emitted by this echosounder is at frequencies near 12 kHz, and the maximum source level is 242 dB re: 1 μPa. The beam is narrow (1 to 2°) in fore-aft extent and wide (150°) in the cross-track extent. Each ping consists of eight (in water greater than 1,000 m deep) or four (less than 1,000 m deep) successive fan-shaped transmissions (segments) at different cross-track angles. Any given mammal at depth near the trackline would be in the main beam for only one or two of the segments. Also, marine mammals that encounter the Kongsberg EM 122 are unlikely to be subjected to repeated pulses because of the narrow fore-aft width of the beam and will receive only limited amounts of pulse energy because of the short pulses. Animals close to the vessel (where the beam is narrowest) are especially unlikely to be ensonified for more than one 2- to 15-ms pulse (or two pulses if in the overlap area). Similarly, Kremser et al. (2005) noted that the probability of a cetacean swimming through the area of exposure when an echosounder emits a pulse is small. The animal would have to pass the transducer at close range and be swimming at speeds similar to the vessel in order to receive the multiple pulses that might result in sufficient exposure to cause temporary threshold shift.

NMFS has considered the potential for behavioral responses such as stranding and indirect injury or mortality from Lamont-Doherty's use of the multibeam echosounder. In 2013, an International Scientific Review Panel (ISRP) investigated a 2008 mass stranding of approximately 100 melon-headed whales in a Madagascar lagoon system (Southall et al., 2013) associated with the use of a high-frequency mapping system. The report indicated that the use of a 12-kHz multibeam echosounder was the most plausible and likely initial behavioral trigger of the mass stranding event. This was the first time that a relatively high-frequency mapping sonar system had been associated with a stranding event. However, the report also notes that there were several site- and situation-specific secondary factors that may have contributed to the avoidance responses that lead to the eventual entrapment and mortality of the whales within the Loza Lagoon system (e.g., the survey vessel transiting in a north-south direction on the shelf break parallel to the shore may have trapped the animals between the sound source and the shore driving them towards the Loza Lagoon). They concluded that for odontocete cetaceans that hear well in the 10-50 kHz range, where ambient noise is typically quite low, high-power active sonars operating in this range may be more easily audible and have potential effects over larger areas than low frequency systems that have more typically been considered in terms of anthropogenic noise impacts (Southall, et al., 2013). However, the risk may be very low given the extensive use of these systems worldwide on a daily basis and the lack of direct evidence of such responses previously reported (Southall, et al., 2013).

Navy sonars linked to avoidance reactions and stranding of cetaceans: (1) Generally have longer pulse duration than the Kongsberg EM 122; and (2) are often directed close to horizontally versus more downward for the echosounder. The area of possible influence of the echosounder is much smaller-a narrow band below the source vessel. Also, the duration of exposure for a given marine mammal can be much longer for naval sonar. During Lamont-Doherty's operations, the individual pulses will be very short, and a given mammal would not receive many of the downward-directed pulses as the vessel passes by the animal. The following section outlines possible effects of an echosounder on marine mammals.

Masking: Marine mammal communications would not be masked appreciably by the echosounder's signals given the low duty cycle of the echosounder and the brief period when an individual mammal is likely to be within its beam. Furthermore, in the case of baleen whales, the echosounder's signals (12 kHz) do not overlap with the predominant frequencies in the calls, which would avoid any significant masking.

Behavioral Responses: Behavioral reactions of free-ranging marine mammals to sonars, echosounders, and other sound sources appear to vary by species and circumstance. Observed reactions have included increased vocalizations and no dispersal by pilot whales (Rendell and Gordon, 1999), and strandings by beaked whales. During exposure to a 21 to 25 kHz “whale-finding” sonar with a source level of 215 dB re: 1 µPa, gray whales reacted by orienting slightly away from the source and being deflected from their course by approximately 200 m (Frankel, 2005). When a 38-kHz echosounder and a 150-kHz acoustic Doppler current profiler were transmitting during studies in the eastern tropical Pacific Ocean, baleen whales showed no significant responses, while spotted and spinner dolphins were detected slightly more often and beaked whales less often during visual surveys (Gerrodette and Pettis, 2005).

Captive bottlenose dolphins and a beluga whale exhibited changes in behavior when exposed to 1-s tonal signals at frequencies similar to those emitted by Lamont-Doherty's echosounder and to shorter broadband pulsed signals. Behavioral changes typically involved what appeared to be deliberate attempts to avoid the sound exposure (Schlundt et al., 2000; Finneran et al., 2002; Finneran and Schlundt, 2004). The relevance of those data to free-ranging odontocetes is uncertain, and in any case, the test sounds were quite different in duration as compared with those from an echosounder.

Hearing Impairment and Other Physical Effects: Given recent stranding events associated with the operation of mid-frequency tactical sonar, there is concern that mid-frequency sonar sounds can cause serious impacts to marine mammals (see earlier discussion). However, the echosounder proposed for use by the Langseth is quite different from sonar used for naval operations. The echosounder's pulse duration is very short relative to the naval sonar. Also, at any given location, an individual marine mammal would be in the echosounder's beam for much less time given the generally downward orientation of the beam and its narrow fore-aft beamwidth; navy sonar often uses near-horizontally-directed sound. Those factors would all reduce the sound energy received from the echosounder relative to that from naval sonar.

Lamont-Doherty would also operate a sub-bottom profiler from the source vessel during the proposed survey. The profiler's sounds are very short pulses, occurring for one to four ms once every second. Most of the energy in the sound pulses emitted by the profiler is at 3.5 kHz, and the beam is directed downward. The sub-bottom profiler on the Langseth has a maximum source level of 222 dB re: 1 µPa. 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—even for a profiler more powerful than that on the Langseth—if the animal was in the area, it would have to pass the transducer at close range and in order to be subjected to sound levels that could cause temporary threshold shift.

Masking: Marine mammal communications would not 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, in the case of most baleen whales, 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. However, the pulsed signals from the profiler are considerably weaker than those from the echosounder.

Hearing Impairment and Other Physical Effects: It is unlikely that the profiler produces pulse levels strong enough to cause hearing impairment or other physical injuries even in an animal that is (briefly) in a position near the source. The profiler operates simultaneously with other higher-power acoustic sources. Many marine mammals would move away in response to the approaching higher-power sources or the vessel itself before the mammals would be close enough for there to be any possibility of effects from the less intense sounds from the profiler.

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:

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.

Baleen whales: When baleen whales receive low-level sounds from distant or stationary vessels, the sounds often seem to be ignored. Some whales approach the sources of these sounds. When vessels approach whales slowly and non-aggressively, whales often exhibit slow and inconspicuous avoidance maneuvers. In response to strong or rapidly changing vessel noise, baleen whales often interrupt their normal behavior and swim rapidly away. Avoidance is especially strong when a boat heads directly toward the whale.

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).

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 seismic survey would require towing approximately 8.0 km (4.9 mi) of equipment and 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. Lamont-Doherty has no recorded cases of entanglement of marine mammals during their conduct of over 11 years of seismic surveys (NSF, 2015).

Anticipated Effects on Marine Mammal Habitat

The primary potential impacts to marine mammal habitat and other marine species are associated with elevated sound levels produced by airguns. This section describes the potential impacts to marine mammal habitat from the specified activity.

Anticipated Effects on Fish

NMFS considered the effects of the survey on marine mammal prey (i.e., fish and invertebrates), as a component of marine mammal habitat in the following subsections.

There are three types of potential effects of exposure to seismic surveys: (1) Pathological, (2) physiological, and (3) behavioral. Pathological effects involve lethal and temporary or permanent sub-lethal injury. Physiological effects involve temporary and permanent primary and secondary stress responses, such as changes in levels of enzymes and proteins. Behavioral effects refer to temporary and (if they occur) permanent changes in exhibited behavior (e.g., startle and avoidance behavior). The three categories are interrelated in complex ways. For example, it is possible that certain physiological and behavioral changes could potentially lead to an ultimate pathological effect on individuals (i.e., mortality).

The available information on the impacts of seismic surveys on marine fish is from studies of individuals or portions of a population. There have been no studies at the population scale. The studies of individual fish have often been on caged fish that were exposed to airgun pulses in situations not representative of an actual seismic survey. Thus, available information provides limited insight on possible real-world effects at the ocean or population scale.

Hastings and Popper (2005), Popper (2009), and Popper and Hastings (2009) provided recent critical reviews of the known effects of sound on fish. The following sections provide a general synopsis of the available information on the effects of exposure to seismic and other anthropogenic sound as relevant to fish. The information comprises results from scientific studies of varying degrees of rigor plus some anecdotal information. Some of the data sources may have serious shortcomings in methods, analysis, interpretation, and reproducibility that must be considered when interpreting their results (see Hastings and Popper, 2005). Potential adverse effects of the program's sound sources on marine fish are noted.

Pathological Effects: The potential for pathological damage to hearing structures in fish depends on the energy level of the received sound and the physiology and hearing capability of the species in question. For a given sound to result in hearing loss, the sound must exceed, by some substantial amount, the hearing threshold of the fish for that sound (Popper, 2005). The consequences of temporary or permanent hearing loss in individual fish on a fish population are unknown; however, they likely depend on the number of individuals affected and whether critical behaviors involving sound (e.g., predator avoidance, prey capture, orientation and navigation, reproduction, etc.) are adversely affected.

There are few data about the mechanisms and characteristics of damage impacting fish that by exposure to seismic survey sounds. Peer-reviewed scientific literature has presented few data on this subject. NMFS is aware of only two papers with proper experimental methods, controls, and careful pathological investigation that implicate sounds produced by actual seismic survey airguns in causing adverse anatomical effects. One such study indicated anatomical damage, and the second indicated temporary threshold shift in fish hearing. The anatomical case is McCauley et al. (2003), who found that exposure to airgun sound caused observable anatomical damage to the auditory maculae of pink snapper (Pagrus auratus). This damage in the ears had not been repaired in fish sacrificed and examined almost two months after exposure. On the other hand, Popper et al. (2005) documented only temporary threshold shift (as determined by auditory brainstem response) in two of three fish species from the Mackenzie River Delta. This study found that broad whitefish (Coregonus nasus) exposed to five airgun shots were not significantly different from those of controls. During both studies, the repetitive exposure to sound was greater than would have occurred during a typical seismic survey. However, the substantial low-frequency energy produced by the airguns (less than 400 Hz in the study by McCauley et al. (2003) and less than approximately 200 Hz in Popper et al. (2005)) likely did not propagate to the fish because the water in the study areas was very shallow (approximately 9 m in the former case and less than 2 m in the latter). Water depth sets a lower limit on the lowest sound frequency that will propagate (i.e., the cutoff frequency) at about one-quarter wavelength (Urick, 1983; Rogers and Cox, 1988).

Wardle et al. (2001) suggested that in water, acute injury and death of organisms exposed to seismic energy depends primarily on two features of the sound source: (1) The received peak pressure and (2) the time required for the pressure to rise and decay. Generally, as received pressure increases, the period for the pressure to rise and decay decreases, and the chance of acute pathological effects increases. According to Buchanan et al. (2004), for the types of seismic airguns and arrays involved with the proposed program, the pathological (mortality) zone for fish would be expected to be within a few meters of the seismic source. Numerous other studies provide examples of no fish mortality upon exposure to seismic sources (Falk and Lawrence, 1973; Holliday et al., 1987; La Bella et al., 1996; Santulli et al., 1999; McCauley et al., 2000a,b, 2003; Bjarti, 2002; Thomsen, 2002; Hassel et al., 2003; Popper et al., 2005; Boeger et al., 2006).

The National Park Service conducted an experiment of the effects of a single 700 in³ airgun in Lake Meade, Nevada (USGS, 1999) to understand the effects of a marine reflection survey of the Lake Meade fault system (Paulson et al., 1993, in USGS, 1999). The researchers suspended the airgun 3.5 m (11.5 ft) above a school of threadfin shad in Lake Meade and fired three successive times at a 30 s interval. Neither surface inspection nor diver observations of the water column and bottom found any dead fish.

For a proposed seismic survey in Southern California, USGS (1999) conducted a review of the literature on the effects of airguns on fish and fisheries. They reported a 1991 study of the Bay Area Fault system from the continental shelf to the Sacramento River, using a 10 airgun (5,828 in³) array. Brezzina and Associates, hired by USGS to monitor the effects of the surveys, concluded that airgun operations were not responsible for the death of any of the fish carcasses observed, and the airgun profiling did not appear to alter the feeding behavior of sea lions, seals, or pelicans observed feeding during the seismic surveys.

Some studies have reported that mortality of fish, fish eggs, or larvae can occur close to seismic sources (Kostyuchenko, 1973; Dalen and Knutsen, 1986; Booman et al., 1996; Dalen et al., 1996). Some of the reports claimed seismic effects from treatments quite different from actual seismic survey sounds or even reasonable surrogates. However, Payne et al. (2009) reported no statistical differences in mortality/morbidity between control and exposed groups of capelin eggs or monkfish larvae. Saetre and Ona (1996) applied a worst-case scenario, mathematical model to investigate the effects of seismic energy on fish eggs and larvae. The authors concluded that mortality rates caused by exposure to seismic surveys were low, as compared to natural mortality rates, and suggested that the impact of seismic surveying on recruitment to a fish stock was not significant.

Physiological Effects: Physiological effects refer to cellular and/or biochemical responses of fish to acoustic stress. Such stress potentially could affect fish populations by increasing mortality or reducing reproductive success. Primary and secondary stress responses of fish after exposure to seismic survey sound appear to be temporary in all studies done to date (Sverdrup et al., 1994; Santulli et al., 1999; McCauley et al., 2000a,b). The periods necessary for the biochemical changes to return to normal are variable and depend on numerous aspects of the biology of the species and of the sound stimulus.

Behavioral Effects—Behavioral effects include changes in the distribution, migration, mating, and catchability of fish populations. Studies investigating the possible effects of sound (including seismic survey sound) on fish behavior have been conducted on both uncaged and caged individuals (e.g., Chapman and Hawkins, 1969; Pearson et al., 1992; Santulli et al., 1999; Wardle et al., 2001; Hassel et al., 2003). Typically, in these studies fish exhibited a sharp startle response at the onset of a sound followed by habituation and a return to normal behavior after the sound ceased.

The former Minerals Management Service (MMS, 2005) assessed the effects of a proposed seismic survey in Cook Inlet, Alaska. The seismic survey proposed using three vessels, each towing two, four-airgun arrays ranging from 1,500 to 2,500 in³. The Minerals Management Service noted that the impact to fish populations in the survey area and adjacent waters would likely be very low and temporary and also concluded that seismic surveys may displace the pelagic fishes from the area temporarily when airguns are in use. However, fishes displaced and avoiding the airgun noise are likely to backfill the survey area in minutes to hours after cessation of seismic testing. Fishes not dispersing from the airgun noise (e.g., demersal species) may startle and move short distances to avoid airgun emissions.

In general, any adverse effects on fish behavior or fisheries attributable to seismic testing may depend on the species in question and the nature of the fishery (season, duration, fishing method). They may also depend on the age of the fish, its motivational state, its size, and numerous other factors that are difficult, if not impossible, to quantify at this point, given such limited data on effects of airguns on fish, particularly under realistic at-sea conditions (Lokkeborg et al., 2012; Fewtrell and McCauley, 2012). NMFS would expect prey species to return to their pre-exposure behavior once seismic firing ceased (Lokkeborg et al., 2012; Fewtrell and McCauley, 2012).

Anticipated Effects on Invertebrates

The existing body of information on the impacts of seismic survey sound on marine invertebrates is very limited. However, there is some unpublished and very limited evidence of the potential for adverse effects on invertebrates, thereby justifying further discussion and analysis of this issue. The three types of potential effects of exposure to seismic surveys on marine invertebrates are pathological, physiological, and behavioral. Based on the physical structure of their sensory organs, marine invertebrates appear to be specialized to respond to particle displacement components of an impinging sound field and not to the pressure component (Popper et al., 2001). The only information available on the impacts of seismic surveys on marine invertebrates involves studies of individuals; there have been no studies at the population scale. Thus, available information provides limited insight on possible real-world effects at the regional or ocean scale.

Moriyasu et al. (2004) and Payne et al. (2008) provide literature reviews of the effects of seismic and other underwater sound on invertebrates. The following sections provide a synopsis of available information on the effects of exposure to seismic survey sound on species of decapod crustaceans and cephalopods, the two taxonomic groups of invertebrates on which most such studies have been conducted. The available information is from studies with variable degrees of scientific soundness and from anecdotal information. A more detailed review of the literature on the effects of seismic survey sound on invertebrates is in Appendix E of Foundation's 2011 Programmatic Environmental Impact Statement (NSF/USGS, 2011).

Pathological Effects: In water, lethal and sub-lethal injury to organisms exposed to seismic survey sound appears to depend on at least two features of the sound source: (1) The received peak pressure; and (2) the time required for the pressure to rise and decay. Generally, as received pressure increases, the period for the pressure to rise and decay decreases, and the chance of acute pathological effects increases. For the type of airgun array planned for the proposed program, the pathological (mortality) zone for crustaceans and cephalopods is expected to be within a few meters of the seismic source, at most; however, very few specific data are available on levels of seismic signals that might damage these animals. This premise is based on the peak pressure and rise/decay time characteristics of seismic airgun arrays currently in use around the world.

Some studies have suggested that seismic survey sound has a limited pathological impact on early developmental stages of crustaceans (Pearson et al., 1994; Christian et al., 2003; DFO, 2004). However, the impacts appear to be either temporary or insignificant compared to what occurs under natural conditions. Controlled field experiments on adult crustaceans (Christian et al., 2003, 2004; DFO, 2004) and adult cephalopods (McCauley et al., 2000a,b) exposed to seismic survey sound have not resulted in any significant pathological impacts on the animals. It has been suggested that exposure to commercial seismic survey activities has injured giant squid (Guerra et al., 2004), but the article provides little evidence to support this claim.

Tenera Environmental (2011) reported that Norris and Mohl (1983, summarized in Mariyasu et al., 2004) observed lethal effects in squid (Loligo vulgaris) at levels of 246 to 252 dB after 3 to 11 minutes. Another laboratory study observed abnormalities in larval scallops after exposure to low frequency noise in tanks (de Soto et al., 2013).

Andre et al. (2011) exposed four cephalopod species (Loligo vulgaris, Sepia officinalis, Octopus vulgaris, and Ilex coindetii) to two hours of continuous sound from 50 to 400 Hz at 157 ±5 dB re: 1 μPa. They reported lesions to the sensory hair cells of the statocysts of the exposed animals that increased in severity with time, suggesting that cephalopods are particularly sensitive to low-frequency sound. The received sound pressure level was 157 ±5 dB re: 1 µPa, with peak levels at 175 dB re: 1 µPa. As in the McCauley et al. (2003) paper on sensory hair cell damage in pink snapper as a result of exposure to seismic sound, the cephalopods were subjected to higher sound levels than they would be under natural conditions, and they were unable to swim away from the sound source.

Physiological Effects: Physiological effects refer mainly to biochemical responses by marine invertebrates to acoustic stress. Such stress potentially could affect invertebrate populations by increasing mortality or reducing reproductive success. Studies have noted primary and secondary stress responses (i.e., changes in haemolymph levels of enzymes, proteins, etc.) of crustaceans occurring several days or months after exposure to seismic survey sounds (Payne et al., 2007). The authors noted that crustaceans exhibited no behavioral impacts (Christian et al., 2003, 2004; DFO, 2004). The periods necessary for these biochemical changes to return to normal are variable and depend on numerous aspects of the biology of the species and of the sound stimulus.

Behavioral Effects: There is increasing interest in assessing the possible direct and indirect effects of seismic and other sounds on invertebrate behavior, particularly in relation to the consequences for fisheries. Changes in behavior could potentially affect such aspects as reproductive success, distribution, susceptibility to predation, and catchability by fisheries. Studies investigating the possible behavioral effects of exposure to seismic survey sound on crustaceans and cephalopods have been conducted on both uncaged and caged animals. In some cases, invertebrates exhibited startle responses (e.g., squid in McCauley et al., 2000). In other cases, the authors observed no behavioral impacts (e.g., crustaceans in Christian et al., 2003, 2004; DFO, 2004). There have been anecdotal reports of reduced catch rates of shrimp shortly after exposure to seismic surveys; however, other studies have not observed any significant changes in shrimp catch rate (Andriguetto-Filho et al., 2005). Similarly, Parry and Gason (2006) did not find any evidence that lobster catch rates were affected by seismic surveys. Any adverse effects on crustacean and cephalopod behavior or fisheries attributable to seismic survey sound depend on the species in question and the nature of the fishery (season, duration, fishing method).

In examining impacts to fish and invertebrates as prey species for marine mammals, we expect fish to exhibit a range of behaviors including no reaction or habituation (Peña et al., 2013) to startle responses and/or avoidance (Fewtrell and McCauley, 2012). We expect that the seismic survey would have no more than a temporary and minimal adverse effect on any fish or invertebrate species. Although there is a potential for injury to fish or marine life in close proximity to the vessel, we expect that the impacts of the seismic survey on fish and other marine life specifically related to acoustic activities would be temporary in nature, negligible, and would not result in substantial impact to these species or to their role in the ecosystem. Based on the preceding discussion, NMFS does not anticipate that the proposed activity would have any habitat-related effects that could cause significant or long-term consequences for individual marine mammals or their populations.

Proposed 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).

Lamont-Doherty has reviewed the following source documents and has incorporated a suite of proposed mitigation measures into their project description.

(1) Protocols used during previous Lamont-Doherty and Foundation-funded seismic research cruises as approved by us and detailed in the Foundation's 2011 PEIS and 2015 draft environmental analysis;

(2) Previous incidental harassment authorizations applications and authorizations that NMFS has approved and authorized; and

(3) Recommended best practices in Richardson et al. (1995), Pierson et al. (1998), and Weir and Dolman, (2007).

To reduce the potential for disturbance from acoustic stimuli associated with the activities, Lamont-Doherty, and/or its designees have proposed to implement the following mitigation measures for marine mammals:

(1) Vessel-based visual mitigation monitoring;

(2) Proposed exclusion zones;

(3) Power down procedures;

(4) Shutdown procedures;

(5) Ramp-up procedures; and

(6) Speed and course alterations.

NMFS reviewed Lamont-Doherty's proposed mitigation measures and has proposed additional measures to effect the least practicable adverse impact on marine mammals. They are:

(1) Expanded shutdown procedures for all pinnipeds, including Mediterranean monk seals;

(2) Expanded power down procedures for concentrations of six or more whales that do not appear to be traveling (e.g., feeding, socializing, etc.).

(3) Delayed conduct of the three tracklines nearest to Anafi Island as late as possible (i.e., late November to early December) during the proposed survey.

Vessel-Based Visual Mitigation Monitoring

Lamont-Doherty would position observers aboard the seismic source vessel to watch for marine mammals near the vessel during daytime airgun operations and during any start-ups at night. Observers would also watch for marine mammals near the seismic vessel for at least 30 minutes prior to the start of airgun operations after an extended shutdown (i.e., greater than approximately eight minutes for this proposed cruise). When feasible, the observers would conduct observations during daytime periods when the seismic system is not operating for comparison of sighting rates and behavior with and without airgun operations and between acquisition periods. Based on the observations, the Langseth would power down or shutdown the airguns when marine mammals are observed within or about to enter a designated exclusion zone for cetaceans or pinnipeds.

During seismic operations, at least four protected species observers would be aboard the Langseth. Lamont-Doherty would appoint the observers with NMFS concurrence and they would conduct observations during ongoing daytime operations and nighttime ramp-ups of the airgun array. During the majority of seismic operations, two observers would be on duty from the observation tower to monitor marine mammals near the seismic vessel. Using two observers would increase the effectiveness of detecting animals near the source vessel. However, during mealtimes and bathroom breaks, it is sometimes difficult to have two observers on effort, but at least one observer would be on watch during bathroom breaks and mealtimes. Observers would be on duty in shifts of no longer than four hours in duration.

Two observers on the Langseth would also be on visual watch during all nighttime ramp-ups of the seismic airguns. A third observer would monitor the passive acoustic monitoring equipment 24 hours a day to detect vocalizing marine mammals present in the action area. In summary, a typical daytime cruise would have scheduled two observers (visual) on duty from the observation tower, and an observer (acoustic) on the passive acoustic monitoring system. Before the start of the seismic survey, Lamont-Doherty would instruct the vessel's crew to assist in detecting marine mammals and implementing mitigation requirements.

The Langseth is a suitable platform for marine mammal observations. When stationed on the observation platform, the eye level would be approximately 21.5 m (70.5 ft) above sea level, and the observer would have a good view around the entire vessel. During daytime, the observers would scan the area around the vessel systematically with reticle binoculars (e.g., 7 x 50 Fujinon), Big-eye binoculars (25 x 150), and with the naked eye. During darkness, night vision devices would be available (ITT F500 Series Generation 3 binocular-image intensifier or equivalent), when required. Laser range-finding binoculars (Leica LRF 1200 laser rangefinder or equivalent) would be available to assist with distance estimation. They are useful in training observers to estimate distances visually, but are generally not useful in measuring distances to animals directly. The user measures distances to animals with the reticles in the binoculars.

Lamont-Doherty would immediately power down or shutdown the airguns when observers see marine mammals within or about to enter the designated exclusion zone. The observer(s) would continue to maintain watch to determine when the animal(s) are outside the exclusion zone by visual confirmation. Airgun operations would not resume until the observer has confirmed that the animal has left the zone, or if not observed after 15 minutes for species with shorter dive durations (small odontocetes and pinnipeds) or 30 minutes for species with longer dive durations (mysticetes and large odontocetes, including sperm, pygmy sperm, dwarf sperm, killer, and beaked whales).

Proposed Mitigation Exclusion Zones

Lamont-Doherty would use safety radii to designate exclusion zones and to estimate take for marine mammals. Table 3 shows the distances at which one would expect to receive sound levels (160-, 180-, and 190-dB,) from the airgun array and a single airgun. If the protected species visual observer detects marine mammal(s) within or about to enter the appropriate exclusion zone, the Langseth crew would immediately power down the airgun array, or perform a shutdown if necessary (see Shut-down Procedures).

The 180- or 190-dB level shutdown criteria are applicable to cetaceans as specified by NMFS (2000). Lamont-Doherty used these levels to establish the exclusion zones as presented in their application.

Lamont-Doherty used a process to develop and confirm the conservativeness of the mitigation radii for a shallow-water seismic survey in the northeast Pacific Ocean offshore Washington in 2012. Crone et al. (2014) analyzed the received sound levels from the 2012 survey and reported that the actual distances for the exclusion and buffer zones were two to three times smaller than what Lamont-Doherty's modeling approach predicted. While these results confirm the role that bathymetry plays in propagation, they also confirm that empirical measurements from the Gulf of Mexico survey likely over-estimated the size of the exclusion zones for the 2012 Washington shallow-water seismic surveys. NMFS reviewed this preliminary information in consideration of how these data reflect on the accuracy of Lamont-Doherty's current modeling approach.

Power Down Procedures

A power down involves decreasing the number of airguns in use such that the radius of the 180-dB or 190-dB exclusion zone is smaller to the extent that marine mammals are no longer within or about to enter the exclusion zone. A power down of the airgun array can also occur when the vessel is moving from one seismic line to another. During a power down for mitigation, the Langseth would operate one airgun (40 in³). The continued operation of one airgun would alert marine mammals to the presence of the seismic vessel in the area. A shutdown occurs when the Langseth suspends all airgun activity.

If the observer detects a marine mammal outside the exclusion zone and the animal is likely to enter the zone, the crew would power down the airguns to reduce the size of the 180-dB or 190-dB exclusion zone before the animal enters that zone. Likewise, if a mammal is already within the zone after detection, the crew would power-down the airguns immediately. During a power down of the airgun array, the crew would operate a single 40-in³ airgun which has a smaller exclusion zone. If the observer detects a marine mammal within or near the smaller exclusion zone around the airgun (Table 3), the crew would shut down the single airgun (see next section).

Resuming Airgun Operations after a Power Down: Following a power-down, the Langseth crew would not resume full airgun activity until the marine mammal has cleared the 180-dB or 190-dB exclusion zone. The observers would consider the animal to have cleared the exclusion zone if:

• The observer has visually observed the animal leave the exclusion zone; or
• An observer has not sighted the animal within the exclusion zone for 15 minutes for species with shorter dive durations (i.e., small odontocetes or pinnipeds), or 30 minutes for species with longer dive durations (i.e., mysticetes and large odontocetes, including sperm, pygmy sperm, dwarf sperm, and beaked whales); or

The Langseth crew would resume operating the airguns at full power after 15 minutes of sighting any species with short dive durations (i.e., small odontocetes or pinnipeds). Likewise, the crew would resume airgun operations at full power after 30 minutes of sighting any species with longer dive durations (i.e., mysticetes and large odontocetes, including sperm, pygmy sperm, dwarf sperm, and beaked whales).

NMFS estimates that the Langseth would transit outside the original 180-dB or 190-dB exclusion zone after an 8-minute wait period. This period is based on the average speed of the Langseth while operating the airguns (8.5 km/h; 5.3 mph). Because the vessel has transited away from the vicinity of the original sighting during the 8-minute period, implementing ramp-up procedures for the full array after an extended power down (i.e., transiting for an additional 35 minutes from the location of initial sighting) would not meaningfully increase the effectiveness of observing marine mammals approaching or entering the exclusion zone for the full source level and would not further minimize the potential for take. The Langseth's observers are continually monitoring the exclusion zone for the full source level while the mitigation airgun is firing. On average, observers can observe to the horizon (10 km; 6.2 mi) from the height of the Langseth's observation deck and should be able to say with a reasonable degree of confidence whether a marine mammal would be encountered within this distance before resuming airgun operations at full power.

Shutdown Procedures

The Langseth crew would shut down the operating airgun(s) if they see a marine mammal within or approaching the exclusion zone for the single airgun. The crew would implement a shutdown:

(1) If an animal enters the exclusion zone of the single airgun after the crew has initiated a power down; or

(2) If an observer sees the animal is initially within the exclusion zone of the single airgun when more than one airgun (typically the full airgun array) is operating.

Resuming Airgun Operations after a Shutdown: Following a shutdown in excess of eight minutes, the Langseth crew would initiate a ramp-up with the smallest airgun in the array (40-in³). The crew would turn on additional airguns in a sequence such that the source level of the array would increase in steps not exceeding 6 dB per five-minute period over a total duration of approximately 30 minutes. During ramp-up, the observers would monitor the exclusion zone, and if he/she sees a marine mammal, the Langseth crew would implement a power down or shutdown as though the full airgun array were operational.

During periods of active seismic operations, there are occasions when the Langseth crew would need to temporarily shut down the airguns due to equipment failure or for maintenance. In this case, if the airguns are inactive longer than eight minutes, the crew would follow ramp-up procedures for a shutdown described earlier and the observers would monitor the full exclusion zone and would implement a power down or shutdown if necessary.

If the full exclusion zone is not visible to the observer for at least 30 minutes prior to the start of operations in either daylight or nighttime, the Langseth crew would not commence ramp-up unless at least one airgun (40-in³ or similar) has been operating during the interruption of seismic survey operations. Given these provisions, it is likely that the vessel's crew would not ramp-up the airgun array from a complete shutdown at night or in thick fog, because the outer part of the zone for that array would not be visible during those conditions.

If one airgun has operated during a power down period, ramp-up to full power would be permissible at night or in poor visibility, on the assumption that marine mammals would be alerted to the approaching seismic vessel by the sounds from the single airgun and could move away. The vessel's crew would not initiate a ramp-up of the airguns if an observer sees the marine mammal within or near the applicable exclusion zones during the day or close to the vessel at night.

Ramp-Up Procedures

Ramp-up of an airgun array provides a gradual increase in sound levels, and involves a step-wise increase in the number and total volume of airguns firing until the full volume of the airgun array is achieved. The purpose of a ramp-up is to “warn” marine mammals in the vicinity of the airguns, and to provide the time for them to leave the area and thus avoid any potential injury or impairment of their hearing abilities. Lamont-Doherty would follow a ramp-up procedure when the airgun array begins operating after an 8-minute period without airgun operations or when shut down has exceeded that period. Lamont-Doherty has used similar waiting periods (approximately eight to 10 minutes) during previous seismic surveys.

Ramp-up would begin with the smallest airgun in the array (40 in³). The crew would add airguns in a sequence such that the source level of the array would increase in steps not exceeding six dB per five minute period over a total duration of approximately 30 to 35 minutes. During ramp-up, the observers would monitor the exclusion zone, and if marine mammals are sighted, Lamont-Doherty would implement a power-down or shut-down as though the full airgun array were operational.

If the complete exclusion zone has not been visible for at least 30 minutes prior to the start of operations in either daylight or nighttime, Lamont-Doherty would not commence the ramp-up unless at least one airgun (40 in³ or similar) has been operating during the interruption of seismic survey operations. Given these provisions, it is likely that the crew would not ramp-up the airgun array from a complete shut-down at night or in thick fog, because the outer part of the exclusion zone for that array would not be visible during those conditions. If one airgun has operated during a power-down period, ramp-up to full power would be permissible at night or in poor visibility, on the assumption that marine mammals would be alerted to the approaching seismic vessel by the sounds from the single airgun and could move away. Lamont-Doherty would not initiate a ramp-up of the airguns if an observer sights a marine mammal within or near the applicable exclusion zones. NMFS refers the reader to Figure 2, which presents a flowchart representing the ramp-up, power down, and shut down protocols described in this notice.

Special Procedures for Situations or Species of Concern

Considering the highly endangered status of Mediterranean monk seals, the Langseth crew would shut down the airgun(s) immediately in the unlikely event that observers detect any pinniped species within any visible distance of the vessel. The Langseth would only begin ramp-up if observers have not seen the Mediterranean monk seal for 30 minutes.

To further reduce impacts to Mediterranean monk seals during the peak of the pupping season (September through November), NMFS is requiring Lamont-Doherty to conduct the three proposed tracklines nearest to Anafi Island as late as possible (i.e., late November to early December) during the proposed survey.

Last, the Langseth would avoid exposing concentrations of large whales to sounds greater than 160 dB and would power down the array, if necessary. For purposes of this proposed survey, a concentration or group of whales would consist of six or more individuals visually sighted that do not appear to be traveling (e.g., feeding, socializing, etc.).

Speed and Course Alterations

If during seismic data collection, Lamont-Doherty detects marine mammals outside the exclusion zone and, based on the animal's position and direction of travel, is likely to enter the exclusion zone, the Langseth would change speed and/or direction if this does not compromise operational safety. Due to the limited maneuverability of the primary survey vessel, altering speed, and/or course can result in an extended period of time to realign the Langseth to the transect line. However, if the animal(s) appear likely to enter the exclusion zone, the Langseth would undertake further mitigation actions, including a power down or shut down of the airguns.

To the maximum extent practicable, the Langseth would conduct the seismic survey (especially when near land) from the coast (inshore) and proceed towards the sea (offshore) in order to avoid trapping marine mammals in shallow water.

Mitigation Conclusions

NMFS has carefully evaluated Lamont-Doherty's proposed 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:

1. Avoidance or minimization of injury or death of marine mammals wherever possible (goals 2, 3, and 4 may contribute to this goal).

2. 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).

3. 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).

4. 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).

5. 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.

6. 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 Lamont-Doherty's proposed measures, as well as other measures proposed by NMFS, NMFS has preliminarily determined that the proposed 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.

Proposed Monitoring

In order to issue an Incidental Take Authorization for an activity, section 101(a)(5)(D) of the MMPA states that NMFS must set forth “requirements pertaining to the monitoring and reporting of such taking.” The MMPA implementing regulations at 50 CFR 216.104(a)(13) indicate that requests for Authorizations must include the suggested means of accomplishing the necessary monitoring and reporting that will result in increased knowledge of the species and of the level of taking or impacts on populations of marine mammals that we expect to be present in the proposed action area.

Lamont-Doherty submitted a marine mammal monitoring plan in section XIII of the Authorization application. NMFS, NSF, or Lamont-Doherty may modify or supplement the plan based on comments or new information received from the public during the public comment period.

Monitoring measures prescribed by NMFS should accomplish one or more of the following general goals:

1. An increase in the probability of detecting marine mammals, both within the mitigation zone (thus allowing for more effective implementation of the mitigation) and during other times and locations, in order to generate more data to contribute to the analyses mentioned later;

2. An increase in our understanding of how many marine mammals would be affected by seismic airguns and other active acoustic sources and the likelihood of associating those exposures with specific adverse effects, such as behavioral harassment, temporary or permanent threshold shift;

3. An increase in our understanding of how marine mammals respond to stimuli that we expect to result in take and how those anticipated adverse effects on individuals (in different ways and to varying degrees) may impact the population, species, or stock (specifically through effects on annual rates of recruitment or survival) through any of the following methods:

a. Behavioral observations in the presence of stimuli compared to observations in the absence of stimuli (i.e., to be able to accurately predict received level, distance from source, and other pertinent information);

b. Physiological measurements in the presence of stimuli compared to observations in the absence of stimuli (i.e., to be able to accurately predict received level, distance from source, and other pertinent information);

c. Distribution and/or abundance comparisons in times or areas with concentrated stimuli versus times or areas without stimuli;

4. An increased knowledge of the affected species; and

5. An increase in our understanding of the effectiveness of certain mitigation and monitoring measures.

Proposed Monitoring Measures

Lamont-Doherty proposes to sponsor marine mammal monitoring during the present project to supplement the mitigation measures that require real-time monitoring, and to satisfy the monitoring requirements of the Authorization. Lamont-Doherty understands that NMFS would review the monitoring plan and may require refinements to the plan. Lamont-Doherty planned the monitoring work as a self-contained project independent of any other related monitoring projects that may occur in the same regions at the same time. Further, Lamont-Doherty is prepared to discuss coordination of its monitoring program with any other related work that might be conducted by other groups working insofar as it is practical for Lamont-Doherty.

Vessel-Based Passive Acoustic Monitoring

Passive acoustic monitoring would complement the visual mitigation monitoring program, when practicable. Visual monitoring typically is not effective during periods of poor visibility or at night, and even with good visibility, is unable to detect marine mammals when they are below the surface or beyond visual range. Passive acoustical monitoring can improve detection, identification, and localization of cetaceans when used in conjunction with visual observations. The passive acoustic monitoring would serve to alert visual observers (if on duty) when vocalizing cetaceans are detected. It is only useful when marine mammals call, but it can be effective either by day or by night, and does not depend on good visibility. The acoustic observer would monitor the system in real time so that he/she can advise the visual observers if they acoustically detect cetaceans.

The passive acoustic monitoring system consists of hardware (i.e., hydrophones) and software. The “wet end” of the system consists of a towed hydrophone array connected to the vessel by a tow cable. The tow cable is 250 m (820.2 ft) long and the hydrophones are fitted in the last 10 m (32.8 ft) of cable. A depth gauge, attached to the free end of the cable, typically towed at depths less than 20 m (65.6 ft). The Langseth crew would deploy the array from a winch located on the back deck. A deck cable would connect the tow cable to the electronics unit in the main computer lab where the acoustic station, signal conditioning, and processing system would be located. The Pamguard software amplifies, digitizes, and then processes the acoustic signals received by the hydrophones. The system can detect marine mammal vocalizations at frequencies up to 250 kHz.

One acoustic observer, an expert bioacoustician with primary responsibility for the passive acoustic monitoring system would be aboard the Langseth in addition to the four visual observers. The acoustic observer would monitor the towed hydrophones 24 hours per day during airgun operations and during most periods when the Langseth is underway while the airguns are not operating. However, passive acoustic monitoring may not be possible if damage occurs to both the primary and back-up hydrophone arrays during operations. The primary passive acoustic monitoring streamer on the Langseth is a digital hydrophone streamer. Should the digital streamer fail, back-up systems should include an analog spare streamer and a hull-mounted hydrophone.

One acoustic observer would monitor the acoustic detection system by listening to the signals from two channels via headphones and/or speakers and watching the real-time spectrographic display for frequency ranges produced by cetaceans. The observer monitoring the acoustical data would be on shift for one to six hours at a time. The other observers would rotate as an acoustic observer, although the expert acoustician would be on passive acoustic monitoring duty more frequently.

When the acoustic observer detects a vocalization while visual observations are in progress, the acoustic observer on duty would contact the visual observer immediately, to alert him/her to the presence of cetaceans (if they have not already been seen), so that the vessel's crew can initiate a power down or shutdown, if required. The observer would enter the information regarding the call into a database. Data entry would include an acoustic encounter identification number, whether it was linked with a visual sighting, date, time when first and last heard and whenever any additional information was recorded, position and water depth when first detected, bearing if determinable, species or species group (e.g., unidentified dolphin, sperm whale), types and nature of sounds heard (e.g., clicks, continuous, sporadic, whistles, creaks, burst pulses, strength of signal, etc.), and any other notable information. Acousticians record the acoustic detection for further analysis.

Observer Data and Documentation

Observers would record data to estimate the numbers of marine mammals exposed to various received sound levels and to document apparent disturbance reactions or lack thereof. They would use the data to help better understand the impacts of the activity on marine mammals and to estimate numbers of animals potentially `taken' by harassment (as defined in the MMPA). They will also provide information needed to order a power down or shut down of the airguns when a marine mammal is within or near the exclusion zone.

When an observer makes a sighting, they will record the following information:

1. Species, group size, age/size/sex categories (if determinable), behavior when first sighted and after initial sighting, heading (if consistent), bearing and distance from seismic vessel, sighting cue, apparent reaction to the airguns or vessel (e.g., none, avoidance, approach, paralleling, etc.), and behavioral pace.

2. Time, location, heading, speed, activity of the vessel, sea state, visibility, and sun glare.

The observer will record the data listed under (2) at the start and end of each observation watch, and during a watch whenever there is a change in one or more of the variables.

Observers will record all observations and power downs or shutdowns in a standardized format and will enter data into an electronic database. The observers will verify the accuracy of the data entry by computerized data validity checks during data entry and by subsequent manual checking of the database. These procedures will allow the preparation of initial summaries of data during and shortly after the field program, and will facilitate transfer of the data to statistical, graphical, and other programs for further processing and archiving.

Results from the vessel-based observations will provide:

1. The basis for real-time mitigation (airgun power down or shutdown).

2. Information needed to estimate the number of marine mammals potentially taken by harassment, which Lamont-Doherty must report to the Office of Protected Resources.

3. Data on the occurrence, distribution, and activities of marine mammals and turtles in the area where Lamont-Doherty would conduct the seismic study.

4. Information to compare the distance and distribution of marine mammals and turtles relative to the source vessel at times with and without seismic activity.

5. Data on the behavior and movement patterns of marine mammals detected during non-active and active seismic operations.

Proposed Reporting

Lamont-Doherty would submit a report to us and to NSF within 90 days after the end of the cruise. The report would describe the operations conducted and sightings of marine mammals near the operations. The report would provide full documentation of methods, results, and interpretation pertaining to all monitoring. The 90-day report would summarize the dates and locations of seismic operations, and all marine mammal sightings (dates, times, locations, activities, associated seismic survey activities). The report would also include estimates of the number and nature of exposures that occurred above the harassment threshold based on the observations.

In the unanticipated event that the specified activity clearly causes the take of a marine mammal in a manner not permitted by the authorization (if issued), such as an injury, serious injury, or mortality (e.g., ship-strike, gear interaction, and/or entanglement), Lamont-Doherty shall immediately cease the specified activities and immediately report the take to the Chief Permits and Conservation Division, Office of Protected Resources, NMFS. The report must 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).

Lamont-Doherty shall not resume its activities until we are able to review the circumstances of the prohibited take. We shall work with Lamont-Doherty to determine what is necessary to minimize the likelihood of further prohibited take and ensure MMPA compliance. Lamont-Doherty may not resume their activities until notified by us via letter, email, or telephone.

In the event that Lamont-Doherty discovers an injured or dead marine mammal, and the lead visual observer 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 we describe in the next paragraph), Lamont-Doherty will immediately report the incident to the Chief Permits and Conservation Division, Office of Protected Resources, NMFS. The report must include the same information identified in the paragraph above this section. Activities may continue while NMFS reviews the circumstances of the incident. NMFS would work with Lamont-Doherty to determine whether modifications in the activities are appropriate.

In the event that Lamont-Doherty discovers an injured or dead marine mammal, and the lead visual observer determines that the injury or death is not associated with or related to the authorized activities (e.g., previously wounded animal, carcass with moderate to advanced decomposition, or scavenger damage), Lamont-Doherty would report the incident to the Chief Permits and Conservation Division, Office of Protected Resources, NMFS, within 24 hours of the discovery. Lamont-Doherty would provide photographs or video footage (if available) or other documentation of the stranded animal sighting to NMFS.

Estimated Take by Incidental Harassment

Except with respect to certain activities not pertinent here, section 3(18)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 array may have the potential to result in the behavioral disturbance of some marine mammals and may have an even smaller potential to result in permanent threshold shift (non-lethal injury) of some marine mammals. NMFS expects that the proposed mitigation and monitoring measures would minimize the possibility of injurious or lethal takes. However, NMFS cannot discount the possibility (albeit small) that exposure to energy from the proposed survey could result in non-lethal injury (Level A harassment). Thus, NMFS proposes to authorize take by Level B harassment and Level A harassment resulting from the operation of the sound sources for the proposed seismic survey based upon the current acoustic exposure criteria shown in Table 4.

NMFS' practice is to apply the 160 dB re: 1 µPa received level threshold for underwater impulse sound levels to predict whether behavioral disturbance that rises to the level of Level B harassment is likely to occur. NMFS' practice is to apply the 180 dB re: 1 µPa received level threshold for underwater impulse sound levels to predict whether permanent threshold shift (auditory injury), which is considered Level A harassment, is likely to occur.

Acknowledging Uncertainties in Estimating Take

Given the many uncertainties in predicting the quantity and types of impacts of sound on marine mammals, it is common practice to estimate how many animals are likely to be present within a particular distance of a given activity, or exposed to a particular level of sound and use that information to predict how many animals are taken. In practice, depending on the amount of information available to characterize daily and seasonal movement and distribution of affected marine mammals, distinguishing between the number of individuals harassed and the instances of harassment can be difficult to parse. Moreover, when one considers the duration of the activity, in the absence of information to predict the degree to which individual animals are likely exposed repeatedly on subsequent days, the simple assumption is that entirely new animals are exposed in every day, which results in a take estimate that in some circumstances overestimates the number of individuals harassed.

The following sections describe NMFS' methods to estimate take by incidental harassment. We base these estimates on the number of marine mammals that could be harassed by seismic operations with the airgun array during approximately 2,140 km (1,330 mi) of transect lines in the eastern Mediterranean Sea.

Modeled Number of Instances of Exposures in Territorial Waters and High Seas: Lamont-Doherty would conduct the proposed seismic survey within the EEZ and territorial waters of Greece. Greece's territorial seas to extend out to 6 nmi (7 mi; 11 km). The proposed survey would take place partially within Greece's territorial seas (less than 6 nmi [11 km; 7 mi] from the shore) and partially in the high seas. However, NMFS has no authority to authorize the incidental take of marine mammals in the territorial seas of foreign nations, because the MMPA does not apply in those waters. However, NMFS still needs to calculate the level of incidental take in the entire activity area (territorial seas and high seas) as part of the analysis supporting our preliminary determination under the MMPA that the activity will have a negligible impact on the affected species (Table 5). Therefore, NMFS presents estimates of the anticipated numbers of instances that marine mammals would be exposed to sound levels greater than or equal to 160, 180, and 190 dB re: 1 μPa during the proposed seismic survey, both for within the entire action area (i.e., within Greece's territorial seas [less than 6 nmi] and outside of Greece's territorial seas [greater than 6 nmi]—Table 5. Table 6 represents the numbers of instances of take that NMFS proposes to authorize for this survey within the high seas portion of the survey (i.e., the area beyond Greek territorial seas which is outside 6 nmi; 7 mi; 11 km).

NMFS' Take Estimate Method for Species with Density Information: For the proposed Authorization, NMFS reviewed Lamont-Doherty's take estimates presented in Table 3 of their application and propose a more appropriate methodology to estimate take. Lamont-Doherty's approach is to multiply the ensonified area by marine mammal densities (if available) to estimate take. This “snapshot approach” (i.e., area times density) proposed by Lamont-Doherty, assumes a uniform distribution of marine mammals present within the proposed survey area and does not account for the survey occurring over a 16-day period and the overlap of areas across days in that 16-day period.

NMFS has developed an alternate approach that appropriately includes a time component to calculate the take estimates for the proposed survey. In order to estimate the potential number of instances that marine mammals could be exposed to airgun sounds above the 160-dB Level B harassment threshold and the 180-dB Level A harassment thresholds, NMFS used the following approach for species with density estimates:

(1) Calculate the total area that the Langseth would ensonify above the 160-dB Level B harassment threshold and above the 180-dB Level A harassment threshold for cetaceans within a 24-hour period. This calculation includes a daily ensonified area of approximately 1,211 square kilometers (km²) [468 square miles (mi²)] based on the Langseth traveling approximately 200 km [124 mi] in one day). Generally, the Langseth travels approximately 137 km in one day while conducting a seismic survey, thus, NMFS' estimate of a daily ensonified area based on 200 km is an estimation of the theoretical maximum that the Langseth could travel within 24 hours.

(2) Multiply the daily ensonified area above the 160-dB Level B harassment threshold by the species' density to derive the predicted number of instances of exposures to received levels greater than or equal to 160-dB re: 1 μPa on a given day;

(3) Multiply that product (i.e., the expected number of instances of exposures within a day) by the number of survey days that includes a 25 percent contingency (i.e., a total of 20 days) to derive the predicted number of instances of exposures over the duration of the survey;

(4) Multiply the daily ensonified area by each species-specific density to derive the predicted number of instances of exposures to received levels greater than or equal to 180-dB re: 1 μPa for cetaceans on a given day; and (i.e., Level A takes).

(5) Multiply that product by the number of survey days that includes a 25 percent contingency (i.e., a total of 20 days). Subtract that product from the predicted number of instances of exposures to received levels greater than or equal to 160-dB re: 1 μPa on a given day to derive the number of instances of exposures estimated to occur between 160 and 180-dB threshold (i.e., Level B takes).

In many cases, this estimate of instances of exposures is likely an overestimate of the number of individuals that are taken, because it assumes 100 percent turnover in the area every day, (i.e., that each new day results in takes of entirely new individuals with no repeat takes of the same individuals over the 20-day period). However, it is difficult to quantify to what degree NMFS has overestimated the number of individuals potentially affected. Except as described later for a few specific species, NMFS uses this number of instances as the estimate of individuals (and authorized take) even though NMFS is aware that the number is high. This method is a way to help understand the instances of exposure above the Level B and Level A thresholds, however, NMFS notes that method would overestimate the number of individual marine mammals exposed above the 160- or 180-dB threshold.

Take Estimates for Species with No Density Information: Density information for many species of marine mammals in the eastern Mediterranean Sea is data poor or non-existent. When density estimates were not available, NMFS used data based on dedicated survey sighting information from the Atlantic Marine Assessment Program for Protected Species (AMAPPS) surveys in 2010, 2011, and 2013 (AMAPPS, 2010, 2011, 2013) and Boisseau et al. (2010) to estimate take for certain species with no density information. NMFS assumed that Lamont-Doherty could potentially encounter one group of each species during the seismic survey. NMFS believes it is reasonable to use the average (mean) group size (weighted by effort and rounded up) from the AMMAPS surveys to estimate the take from these potential encounters. Those species include the following: Dwarf sperm and pygmy sperm whale (2 each), Gervais', Sowerby's, and Blainville's beaked whales (27 each).

For humpback whale and minke whale, the applicant requested 116 and 1,052 Level B takes for those species, respectively to account for uncertainty in the likelihood of encountering those species during the proposed survey. For these two species which are considered as visitor and vagrant respectively, NMFS believes that it is reasonable to use the average (mean) group size (weighted by effort and rounded up) from the AMMAPS surveys for humpback whale (3) and minke whale (2) and multiply those estimates by 20 days to derive a more reasonable estimate of take. Thus, NMFS proposes a take estimate of 60 humpback whales and 40 minke whales to account for the unlikely possibility of an eruptive occurrence of these species within the proposed action area.

NMFS based the take estimates for rough-toothed dolphins (8), false killer whales (3), long-finned pilot whales (33) and harbor porpoise (1) on mean group size reported from encounter rates observed during visual and acoustic surveys in the Mediterranean Sea, 2003-2007 (Boisseau et al., 2010).

For rarely sighted species such as the gray and Sei whale, NMFS used the mean group size reported in (Boisseau et al., 2010) for Sei whales (1) as a proxy for a take estimate for gray whales (1).

NMFS based the take estimates for hooded seals (1) on stranding and sighting records for the western Mediterranean Sea (Bellido et al., 2008). Based on the best available information, there are no reports of strandings or sightings of hooded seals east of the Gata Cape, Almeria, Span. Researchers suggest the Alboran Sea is the present limit of the sporadic incursion of this species in the Mediterranean Sea (Bellido et al., 2008).

Take Estimates for Mediterranean Monk Seals: Density information for Mediterranean monk seals in the eastern Mediterranean Sea is also data poor or non-existent. NMFS used data based on sighting information from the Rapid Assessment Survey of the Mediterranean monk seal Monachus monachus population in Anafi Island, Cyclades Greece (MOm, 2014). Based on the spatial extent of the survey (three tracklines are approximately 4 km west of Anafi Island). NMFS estimates that the proposed survey could affect approximately 100 percent (25 out of approximately 25 individuals) of the monk seal subpopulation from Anafi Island (Mom, 2014) location within the proposed survey area.

Because adult female Mediterranean monk seals can travel up to 70 km (43 mi) (Adamantopoulou et al., 2011) and based on the spatial extent of the survey in relation to the islands, NMFS conservatively estimates that the proposed survey could affect up to 8 adult females of the monk seal subpopulation from the Kimolos-Polyaigos Island complex in the Cyclades Islands (Politikos et al., 2009) located approximately 60 km (37 mi) northwest of the outer perimeter of the 160-dB ensonified area. NMFS bases the estimate of 8 females on the estimated mean annual pup production count (7.9) for the island complex (UNEP, 2013).

To date, data is unavailable from any systematic survey on the presence of monk seal caves on Santorini Island (Pers. Comm. MOm, 2015). However, based on recent stranding information for one pup on Santorini Island, NMFS estimates that up to two individuals could be present on Santorini Island.

Lamont-Doherty did not estimate any additional take from sound sources other than airguns. NMFS does not expect the sound levels produced by the echosounder and sub-bottom profiler to exceed the sound levels produced by the airguns. Lamont-Doherty will not operate the multibeam echosounder and sub-bottom profiler during transits to and from the survey area, (i.e., when the airguns are not operating), and, therefore, NMFS does not anticipate additional takes from these sources in this particular case.

NMFS considers the probability for entanglement of marine mammals as low because of the vessel speed and the monitoring efforts onboard the survey vessel. Therefore, NMFS does not believe it is necessary to authorize additional takes for entanglement at this time.

The Langseth will operate at a relatively slow speed (typically 4.6 knots [8.5 km/h; 5.3 mph]) when conducting the survey. Protected species observers would monitor for marine mammals, which would trigger mitigation measures, including vessel avoidance where safe. Therefore, NMFS does not anticipate nor do we authorize takes of marine mammals from vessel strike.

There is no evidence that planned activities could result in serious injury or mortality within the specified geographic area for the requested proposed Authorization. The required mitigation and monitoring measures would minimize any potential risk for serious injury or mortality.

Preliminary 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.

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 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.

To avoid repetition, our analysis applies to all the species listed in Table 6, given that NMFS expects the anticipated effects of the seismic airguns to be similar in nature. Where there are meaningful differences between species or stocks, or groups of species, in anticipated individual responses to activities, impact of expected take on the population due to differences in population status, or impacts on habitat (e.g. Mediterranean monk seals), NMFS has identified species-specific factors to inform the analysis.

Given the required mitigation and related monitoring, NMFS does not anticipate that serious injury or mortality would occur as a result of Lamont-Doherty's proposed seismic survey in the eastern Mediterranean Sea. Thus the proposed authorization does not authorize any mortality.

NMFS' predicted estimates for Level A harassment take for bottlenose, striped, short-beaked common, and Risso's dolphins are overestimates of likely injury. NMFS expects that the required visual and acoustic mitigation measures would avoid Level A take in those instances. Also, NMFS expects that some individuals would avoid the source at levels expected to result in injury. NMFS expects that Level A harassment is unlikely but includes the modeled information in this notice. Taking into account that interactions at the modeled level of take for Level A harassment are unlikely due to Lamont-Doherty implementing required mitigation and monitoring measures, the likely avoidance of animals to the sound source, and Lamont-Doherty's previous history of successfully implementing required mitigation measures, the quantified potential injuries in Table 6, if incurred, would be in the form of some lesser degree of permanent threshold shift and not total deafness or mortality.

Given that the Hellenic Republic Ministry of Environment, Energy and Climate Change conducted a larger scale seismic survey in the eastern Mediterranean Sea from mid-November 2012 to end of January 2013, the addition of the increased sound due to the Langseth's operations associated with the proposed seismic survey during a shorter time-frame (approximately 20 days from mid-November to mid-December) is not outside the present experience of marine mammals in the eastern Mediterranean Sea, although levels may increase locally. NMFS does not expect that Lamont-Doherty's 20-day proposed survey would have effects that could cause significant or long-term consequences for individual marine mammals or their populations.

Of the marine mammal species under our jurisdiction that are known to occur or likely to occur in the study area, six of these species are listed as endangered under the ESA including: The fin, humpback, gray, sei, and sperm whales and the Mediterranean monk seal. Population trends for the Mediterranean monk seal globally are variable with some sub populations decreasing and others remaining stable or even indicating slight increases. The western north Atlantic population of humpback whales is known to be increasing. The other marine mammal species that may be taken by harassment during Lamont-Doherty's seismic survey program are not listed as threatened or endangered under the ESA.

Cetaceans. Odontocete reactions to seismic energy pulses are usually thought 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. Given sufficient notice through relatively slow ship speed, NMFS expects marine mammals to move away from a noise source that is annoying prior to becoming potentially injurious.

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 the eastern Mediterranean Sea where feeding by marine mammals occurs versus the localized area of the marine survey activities, any missed feeding opportunities in the direct project area will be minor based on the fact that other feeding areas exist elsewhere. Taking into account the planned mitigation measures, 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.” 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 the Mediterranean Sea will be available for necessary biological functions.

Mediterranean Monk Seal. The Mediterranean monk seal is non-migratory and has a very limited home range (Gucu et al., 2004; Dendrinos et al., 2007a; Adamantopoulou et al., 2011). It historically occupied open beaches, rocky shorelines, and spacious arching caves, but now almost exclusively uses secluded coastal caves for hauling out and breeding. Available data from Greece indicate that Mediterranean monk seals appear to have fairly restricted ranges (from about 100 to 1,000 km²) (Adamantopoulou et al., 2011). Although primary habitat seems to be nearshore shallow waters, movement over deep oceanic waters does occur (Adamantopoulou et al., 2011; Dendrinos et al., 2007a; Sergeant et al., 1978). Unlike most other seal species, Mediterranean monk seals are known to haul-out in grottos or caves frequently accessible only by underwater entrances, (Bareham and Furreddu, 1975; Bayed et al. 2005; CMS, 2005; Dendrinos et al., 2007b) and movement into and out of these locations is not clearly tied to sea or tide state, day or night, or sea/air temperature in some cases (Bareham and Furreddu, 1975; Dendrinos et al., 2001; Marchessaux and Duguy, 1977; Sergeant et al., 1978).

Monk seals are more particular when selecting caves for breeding versus caves for resting (Gücü et al., 2004; Karamanlidis et al., 2004; Dendrinos et al. 2007b). In Greece, the pupping season lasts from August to December with a peak in births during September through November (MOm, 2009). Suitable pupping sites tend to have multiple entrances with soft substrate beaches in their interior which lowers the risk of pup washout (Dendrinos et al., 2007). There are several caves suitable for pupping and/or resting occur near the action area (Dendrinos et al., 2008) including caves for resting and reproduction on Anafi Island located within the eastern perimeter of the proposed action area and on the Kimolos—Polyaigos Island complex located approximately 60 km (37 mi) northwest of the outer perimeter of the proposed action area (Mom, 2014). Taking into account the required mitigation measures to delay the proposed conduct of the three tracklines nearest to Anafi Island as late as possible (i.e., late November to early December) and the required mitigation measure to shut down the airguns any time a pinniped is detected by observers around the vessel, effects on Mediterranean monk seal are generally expected to be restricted to avoidance of a limited area around the survey operation and short-term changes in behavior. NMFS does not expect that the proposed survey would ensonify the caves with pups because the cave's long entrance corridors which act as wave breakers (Dendrinos et al., 2007) could also offer additional protection for lactating pups from sound generated during the proposed survey.

During parturition, lactating females leave the maternity caves as soon as possible after birth in search of food. Based upon a few tagged individuals, lactating female Mediterranean monk seals generally dive in waters 40-60 m deep and have a maximum known dive depth of 180 m (CMS, 2005). Monk seals may focus on areas shallower (2-25 m deep) while foraging (CMS, 2005). Pups tend to remain in shallow, nearshore waters and gradually distribute further from natal caves into waters up to 40 m deep (CMS, 2005; Gazo, 1997; Gazo et al., 2006). In Greek waters, seals may generally stay even closer to their haul-out locations (within a few miles) (Marchessaux and Duguy, 1977).

NMFS expects that it is unlikely that mothers would remain within the cave because of their need to forage and feed their pups. The closest approach of the Langseth to Anafi Island is approximately four km (2.5 mi) away from the northwest portion of the Island. During foraging, Mediterranean monk seal mothers may not react at all to the sound from the proposed survey or may alert, ignore the stimulus, change their behavior, or avoid the immediate area by swimming away or diving. Behavioral responses can range from a mild orienting response, or a shifting of attention, to flight and panic. Research and observations show that pinnipeds in the water are tolerant of anthropogenic noise and activity. They may react in a number of ways depending on their experience with the sound source and what activity they are engaged in at the time of the exposure. Significant behavioral effects are more likely at higher received levels within a few kilometers of the source and activities involving sound from the proposed survey would not occur within the caves where haulout and resting behaviors occur.

Taking into account the required mitigation measures to delay the conduct of survey lines acquired around Anafi Island and the required mitigation measure to shut down the airguns any time a pinniped is detected by observers around the vessel, effects on Mediterranean monk seals 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.” NMFS does not expect the animals to permanently abandon their caves, and any behaviors interrupted during the activity are expected to resume once the short-term activity ceases or moves away.

For reasons stated previously in this document and based on the following factors, Lamont-Doherty's specified activities are not likely to cause long-term behavioral disturbance, permanent threshold shift, or other non-auditory injury, serious injury, or death. They include:

• The anticipated impacts of Lamont-Doherty's survey activities on marine mammals are temporary behavioral changes due to avoidance of the area;
• The likelihood that, given sufficient notice through relatively slow ship speed, NMFS expects marine mammals to move away from a noise source that is annoying prior to its becoming potentially injurious;
• The availability of alternate areas of similar habitat value for marine mammals to temporarily vacate the survey area during the operation of the airgun(s) to avoid acoustic harassment;
• NMFS also expects that the seismic survey would have no more than a temporary and minimal adverse effect on any fish or invertebrate species that serve as prey species for marine mammals, and therefore consider the potential impacts to marine mammal habitat minimal;
• The relatively low potential for temporary or permanent hearing impairment and the likelihood that Lamont-Doherty would avoid this impact through the incorporation of the required monitoring and mitigation measures; and
• The high likelihood that trained visual protected species observers would detect marine mammals at close proximity to the vessel.

Table 6 in this document outlines the number of requested Level A and Level B harassment takes that we anticipate as a result of these activities. NMFS anticipates that 22 marine mammal species could occur in the proposed action area.

Many animals perform vital functions, such as feeding, resting, traveling, and socializing, on a diel cycle (i.e., 24 hour cycle). Behavioral reactions to noise exposure (such as disruption of critical life functions, displacement, or avoidance of important habitat) are more likely to be significant if they last more than one diel cycle or recur on subsequent days (Southall et al., 2007). While NMFS anticipates that the seismic operations would occur on consecutive days, the estimated duration of the survey would last no more than 20 days but would increase sound levels in the marine environment in a relatively small area surrounding the vessel (compared to the range of most of the marine mammals within the proposed survey area), which is constantly travelling over distances, and some animals may only be exposed to and harassed by sound for less than a day.

Required mitigation measures, such as shutdowns for pinnipeds, vessel speed, course alteration, and visual monitoring would be implemented to help reduce impacts to marine mammals. Therefore, the exposure of pinnipeds to sounds produced by this phase of Lamont-Doherty's seismic survey is not anticipated to have an adverse effect on annual rates of recruitment or survival on the Mediterranean monk seal population, and therefore would have a negligible impact.

Based on the analysis herein of the likely effects of the specified activity on marine mammals and their habitat, and taking into consideration the implementation of the proposed monitoring and mitigation measures, NMFS finds that Lamont-Doherty's proposed seismic survey would have a negligible impact on the affected marine mammal species or stocks.

Small Numbers

As mentioned previously, NMFS estimates that Lamont-Doherty's activities could potentially affect, by Level B harassment, 22 species of marine mammals under our jurisdiction. NMFS estimates that Lamont-Doherty's activities could potentially affect, by Level A harassment, up to four species of marine mammals under our jurisdiction.

For each species, the numbers of take being proposed for authorization are small numbers relative to the population sizes: Less than 14 percent for long-finned pilot whales, less than 11 percent of the regional population estimates of Mediterranean monk seals, and less than four percent or less for all other species. NMFS has provided the regional population and take estimates for the marine mammal species that may be taken by Level A and Level B harassment in Table 2 and Table 6 in this notice.

NMFS finds that the proposed incidental take described in Table 6 for the proposed activity would be limited to small numbers relative to the affected species or stocks. 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 Mediterranean, which suggest that for much of the time only a small portion of the population will be accessible to impacts from Lamont-Doherty's activity; (2) the mitigation requirements, which provide spatio-temporal limitations that avoid impacts to large groups of large whales feeding in the action area and limit exposures to sound levels associated with Level A and Level B harassment; (3) the mitigation requirements, which provide spatio-temporal limitations that avoid impacts to Mediterranean monk seals in the action area and limit exposures to sound levels associated with Level A and Level B harassment; (4) the monitoring requirements and mitigation measures described earlier in this document for all marine mammal species that will further reduce the amount of takes; and (5) monitoring results from previous activities that indicated low numbers of marine mammal sightings within the Level A 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.

For two species, when considering take that would occur in the entire action area (including the part within the territorial seas, in which the MMPA does not apply) the number of instances is 11.84 for short-beaked common dolphins and 13.75 percent for short-beaked common dolphins, respectively (Table 5). While these additional takes were not evaluated under the “small number” standard because we are not authorizing them, these total takes (which are overestimates because NMFS' take estimate methodology assumes new exposures every day), were still considered in in our negligible impact determination, which considered all of the effects of the action, even those that occur outside of the jurisdiction of the MMPA.

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

There are no relevant subsistence uses of marine mammals implicated by this action.

Endangered Species Act (ESA)

There are six marine mammal species listed as endangered under the Endangered Species Act that may occur in the proposed survey area. Under section 7 of the ESA, NSF has initiated formal consultation with NMFS on the proposed seismic survey. NMFS (i.e., National Marine Fisheries Service, Office of Protected Resources, Permits and Conservation Division) will also consult internally with NMFS on the proposed issuance of an Authorization under section 101(a)(5)(D) of the MMPA. NMFS and the Foundation will conclude the consultation prior to a determination on the proposed issuance of the Authorization.

National Environmental Policy Act (NEPA)

NSF has prepared a draft EA titled “Draft Environmental Analysis of a Marine Geophysical Survey by the R/V Marcus G. Langseth in the Eastern Mediterranean Sea, November-December, 2015.” NMFS has posted this document on our Web site concurrently with the publication of this notice. NMFS will independently evaluate NSF's NEPA documentation and determine whether or not to adopt it or prepare a separate NEPA analysis and incorporate relevant portions of NSF's draft EA by reference. NMFS will review all comments submitted in response to this notice to complete the NEPA process prior to making a final decision on the Authorization request.

Proposed Authorization

As a result of these preliminary determinations, NMFS proposes issuing an Authorization to Lamont-Doherty for conducting a seismic survey in the eastern Mediterranean Sea, mid-November through mid-December provided they incorporate the proposed mitigation, monitoring, and reporting requirements.

Draft Proposed Authorization

This section contains the draft text for the proposed Authorization. NMFS proposes to include this language in the Authorization if issued.

Incidental Harassment Authorization

We hereby authorize the Lamont-Doherty Earth Observatory (Lamont-Doherty), Columbia University, P.O. Box 1000, 61 Route 9W, Palisades, New York 10964-8000, under section 101(a)(5)(D) of the Marine Mammal Protection Act (MMPA) (16 U.S.C. 1371(a)(5)(D)) and 50 CFR 216.107, to incidentally harass small numbers of marine mammals incidental to a marine geophysical survey conducted by the R/V Marcus G. Langseth (Langseth) marine geophysical survey in the eastern Mediterranean Sea mid-November through mid-December, 2015.

1. Effective Dates

This Authorization is valid from mid-November through December 31, 2015.

2. Specified Geographic Region

This Authorization is valid only for specified activities associated with the R/V Marcus G. Langseth's (Langseth) seismic operations as specified in Lamont-Doherty's Incidental Harassment Authorization (Authorization) application and environmental analysis in the following specified geographic area:

a. In the Aegean Sea, located approximately between 36.1-36.8° N and 24.7-26.1° E in the eastern Mediterranean Sea and over the Hellenic subduction zone which starts in the Aegean Sea at approximately 36.4° N, 23.9° E and runs to the southwest, ending at approximately 34.9° N, 22.6° E, as specified in Lamont-Doherty's application and the National Science Foundation's environmental analysis.

3. Species Authorized and Level of Takes

a. This authorization limits the incidental taking of marine mammals, by harassment only, to the following species in the area described Table 6. Take coverage is only for the area outside Greek territorial waters. The MMPA does not apply within Greek territorial waters.

i. During the seismic activities, if the Holder of this Authorization encounters any marine mammal species that are not listed in Condition 3 for authorized taking and are likely to be exposed to sound pressure levels greater than or equal to 160 decibels (dB) re: 1 μPa, then the Holder must alter speed or course or shut-down the airguns to avoid take.

b. The taking by injury (Level A harassment), serious injury, or death of any of the species listed in Condition 3 or the taking of any kind of any other species of marine mammal is prohibited and may result in the modification, suspension or revocation of this Authorization.

c. This Authorization limits the methods authorized for taking by Level B harassment to the following acoustic sources:

i. A sub-airgun array with a total capacity of 6,600 in³ (or smaller);

4. Reporting Prohibited Take

The Holder of this Authorization must report the taking of any marine mammal in a manner prohibited under this Authorization immediately to the Office of Protected Resources, National Marine Fisheries Service, at 301-427-8401 and/or by email to the Chief, Permits and Conservation Division.

5. Cooperation

We require the Holder of this Authorization to cooperate with the Office of Protected Resources, National Marine Fisheries Service, and any other Federal, state or local agency monitoring the impacts of the activity on marine mammals.

6. Mitigation and Monitoring Requirements

We require the Holder of this Authorization to implement the following mitigation and monitoring requirements when conducting the specified activities to achieve the least practicable adverse impact on affected marine mammal species or stocks:

Visual Observers

a. Utilize two, National Marine Fisheries Service-qualified, vessel-based Protected Species Visual Observers (visual observers) to watch for and monitor marine mammals near the seismic source vessel during daytime airgun operations (from civil twilight-dawn to civil twilight-dusk) and before and during start-ups of airguns day or night.

i. At least one visual observer will be on watch during meal times and restroom breaks.

ii. Observer shifts will last no longer than four hours at a time.

iii. Visual observers will also conduct monitoring while the Langseth crew deploy and recover the airgun array and streamers from the water.

iv. When feasible, visual observers will conduct observations during daytime periods when the seismic system is not operating for comparison of sighting rates and behavioral reactions during, between, and after airgun operations.

v. The Langseth's vessel crew will also assist in detecting marine mammals, when practicable. Visual observers will have access to reticle binoculars (7x50 Fujinon), and big-eye binoculars (25x150).

Exclusion Zones

b. Establish a 180-decibel (dB) or 190-dB exclusion zone for cetaceans and pinnipeds, respectively, before starting the airgun subarray (6,660 in³); and a 180-dB or 190-dB exclusion zone for cetaceans and pinnipeds, respectively for the single airgun (40 in³). Observers will use the predicted radius distance for the 180-dB or 190-dB exclusion zones for cetaceans and pinnipeds.

Visual Monitoring at the Start of Airgun Operations

c. Monitor the entire extent of the exclusion zones for at least 30 minutes (day or night) prior to the ramp-up of airgun operations after a shutdown.

d. Delay airgun operations if the visual observer sees a cetacean within the 180-dB exclusion zone for cetaceans or 190-dB exclusion zone for pinnipeds until the marine mammal(s) has left the area.

i. If the visual observer sees a marine mammal that surfaces, then dives below the surface, the observer shall wait 30 minutes. If the observer sees no marine mammals during that time, he/she should assume that the animal has moved beyond the 180-dB exclusion zone for cetaceans or 190-dB exclusion zone for pinnipeds.

ii. If for any reason the visual observer cannot see the full 180-dB exclusion zone for cetaceans or the 190-dB exclusion zone for pinnipeds for the entire 30 minutes (i.e., rough seas, fog, darkness), or if marine mammals are near, approaching, or within zone, the Langseth may not resume airgun operations.

iii. If one airgun is already running at a source level of at least 180 dB re: 1 μPa or 190 dB re: 1 μPa, the Langseth may start the second gun—and subsequent airguns—without observing relevant exclusion zones for 30 minutes, provided that the observers have not seen any marine mammals near the relevant exclusion zones (in accordance with Condition 6(b)).

Passive Acoustic Monitoring

e. Utilize the passive acoustic monitoring (PAM) system, to the maximum extent practicable, to detect and allow some localization of marine mammals around the Langseth during all airgun operations and during most periods when airguns are not operating. One visual observer and/or bioacoustician will monitor the PAM at all times in shifts no longer than 6 hours. A bioacoustician shall design and set up the PAM system and be present to operate or oversee PAM, and available when technical issues occur during the survey.

f. Do and record the following when an observer detects an animal by the PAM:

i. Notify the visual observer immediately of a vocalizing marine mammal so a power-down or shut-down can be initiated, if required;

ii. enter the information regarding the vocalization into a database. The data to be entered include an acoustic encounter identification number, whether it was linked with a visual sighting, date, time when first and last heard and whenever any additional information was recorded, position, and water depth when first detected, bearing if determinable, species or species group (e.g., unidentified dolphin, sperm whale, monk seal), types and nature of sounds heard (e.g., clicks, continuous, sporadic, whistles, creaks, burst pulses, strength of signal, etc.), and any other notable information.

Ramp-Up Procedures

g. Implement a “ramp-up” procedure when starting the airguns at the beginning of seismic operations or any time after the entire array has been shutdown, which means start the smallest gun first and add airguns in a sequence such that the source level of the array will increase in steps not exceeding approximately 6 dB per 5-minute period. During ramp-up, the observers will monitor the exclusion zone, and if marine mammals are sighted, a course/speed alteration, power-down, or shutdown will be implemented as though the full array were operational.

Recording Visual Detections

h. Visual observers must record the following information when they have sighted a marine mammal:

i. Species, group size, age/size/sex categories (if determinable), behavior when first sighted and after initial sighting, heading (if consistent), bearing and distance from seismic vessel, sighting cue, apparent reaction to the airguns or vessel (e.g., none, avoidance, approach, paralleling, etc., and including responses to ramp-up), and behavioral pace; and

ii. Time, location, heading, speed, activity of the vessel (including number of airguns operating and whether in state of ramp-up or shut-down), Beaufort sea state and wind force, visibility, and sun glare; and

iii. The data listed under 6(f)(ii) at the start and end of each observation watch and during a watch whenever there is a change in one or more of the variables.

Speed or Course Alteration

i. Alter speed or course during seismic operations if a marine mammal, based on its position and relative motion, appears likely to enter the relevant exclusion zone. If speed or course alteration is not safe or practicable, or if after alteration the marine mammal still appears likely to enter the exclusion zone, the Holder of this Authorization will implement further mitigation measures, such as a shutdown.

Power-Down Procedures

j. Power down the airguns if a visual observer detects a marine mammal within, approaching, or entering the relevant exclusion zones. A power-down means reducing the number of operating airguns to a single operating 40 in³ airgun. This would reduce the exclusion zone to the degree that the animal(s) is outside of it.

Resuming Airgun Operations After a Power-Down

k. Following a power-down, if the marine mammal approaches the smaller designated exclusion zone, the airguns must then be completely shut-down. Airgun activity will not resume until the observer has visually observed the marine mammal(s) exiting the exclusion zone and is not likely to return, or has not been seen within the exclusion zone for 15 minutes for species with shorter dive durations (small odontocetes) or 30 minutes for species with longer dive durations (mysticetes and large odontocetes, including sperm, pygmy sperm, dwarf sperm, killer, and beaked whales).

l. Following a power-down and subsequent animal departure, the Langseth may resume airgun operations at full power. Initiation requires that the observers can effectively monitor the full exclusion zones described in Condition 6(b). If the observer sees a marine mammal within or about to enter the relevant zones then the Langseth will implement a course/speed alteration, power-down, or shutdown.

Shutdown Procedures

m. Shutdown the airgun(s) if a visual observer detects a marine mammal within, approaching, or entering the relevant exclusion zone. A shutdown means that the Langseth turns off all operating airguns.

n. If any pinniped is visually sighted, the airgun array will be shut-down regardless of the distance of the animal(s) to the sound source. The array will not resume firing until 30 minutes after the last documented seal visual sighting.

Resuming Airgun Operations After a Shutdown

o. Following a shutdown, if the observer has visually confirmed that the animal has departed the 180-dB zone for cetaceans or the 190-dB zone for pinnipeds within a period of less than or equal to 8 minutes after the shutdown, then the Langseth may resume airgun operations at full power.

p. If the observer has not seen the animal depart the 180-dB zone for cetaceans or the 190-dB zone for pinnipeds, the Langseth shall not resume airgun activity until 15 minutes has passed for species with shorter dive times (i.e., small odontocetes and pinnipeds) or 30 minutes has passed for species with longer dive durations (i.e., mysticetes and large odontocetes, including sperm, pygmy sperm, dwarf sperm, killer, and beaked whales). The Langseth will follow the ramp-up procedures described in Conditions 6(g).

Survey Operations at Night

q. The Langseth may continue marine geophysical surveys into night and low-light hours if the Holder of the Authorization initiates these segment(s) of the survey when the observers can view and effectively monitor the full relevant exclusion zones.

r. This Authorization does not permit the Holder of this Authorization to initiate airgun array operations from a shut-down position at night or during low-light hours (such as in dense fog or heavy rain) when the visual observers cannot view and effectively monitor the full relevant exclusion zones.

s. To the maximum extent practicable, the Holder of this Authorization should schedule seismic operations (i.e., shooting the airguns) during daylight hours.

Mitigation Airgun

t. The Langseth may operate a small-volume airgun (i.e., mitigation airgun) during turns and maintenance at approximately one shot per minute. The Langseth would not operate the small-volume airgun for longer than three hours in duration during turns. During turns or brief transits between seismic tracklines, one airgun would continue to operate.

Special Procedures for Large Whale Concentrations

u. The Langseth will power-down the array and avoid concentrations of fin (Balaenoptera physalus) and/or sperm whales (Physeter macrocephalus) if possible (i.e., avoid exposing concentrations of these animals to sounds greater than 160 dB re: 1 μPa). For purposes of the survey, a concentration or group of whales will consist of six or more individuals visually sighted that do not appear to be traveling (e.g., feeding, socializing, etc.). The Langseth will follow the procedures described in Conditions 6(k) for resuming operations after a power down.

7. Reporting Requirements

This Authorization requires the Holder of this Authorization to:

a. Submit a draft report on all activities and monitoring results to the Office of Protected Resources, National Marine Fisheries Service, within 90 days of the completion of the Langseth's cruise. This report must contain and summarize the following information:

i. Dates, times, locations, heading, speed, weather, sea conditions (including Beaufort sea state and wind force), and associated activities during all seismic operations and marine mammal sightings;

ii. Species, number, location, distance from the vessel, and behavior of any marine mammals, as well as associated seismic activity (number of shutdowns), observed throughout all monitoring activities.

iii. An estimate of the number (by species) of marine mammals with known exposures to the seismic activity (based on visual observation) at received levels greater than or equal to 160 dB re: 1 μPa and/or 180 dB re 1 μPa for cetaceans and 190-dB re 1 μPa for pinnipeds and a discussion of any specific behaviors those individuals exhibited.

iv. An estimate of the number (by species) of marine mammals with estimated exposures (based on modeling results) to the seismic activity at received levels greater than or equal to 160 dB re: 1 μPa and/or 180 dB re 1 μPa for cetaceans and 190-dB re 1 μPa for pinnipeds with a discussion of the nature of the probable consequences of that exposure on the individuals.

v. A description of the implementation and effectiveness of the: (A) Terms and conditions of the Biological Opinion's Incidental Take Statement (attached); and (B) mitigation measures of the Incidental Harassment Authorization. For the Biological Opinion, the report will 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 Endangered Species Act listed marine mammals.

b. Submit a final report to the Chief, Permits and Conservation Division, Office of Protected Resources, National Marine Fisheries Service, within 30 days after receiving comments from us on the draft report. If we decide that the draft report needs no comments, we will consider the draft report to be the final report.

8. Reporting Prohibited Take

In the unanticipated event that the specified activity clearly causes the take of a marine mammal in a manner not permitted by the authorization (if issued), such as an injury, serious injury, or mortality (e.g., ship-strike, gear interaction, and/or entanglement), Lamont-Doherty shall immediately cease the specified activities and immediately report the take to the Chief, Permits and Conservation Division, Office of Protected Resources, NMFS, at 301-427-8401 and/or by email. The report must 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).

Lamont-Doherty shall not resume its activities until we are able to review the circumstances of the prohibited take. We shall work with Lamont-Doherty to determine what is necessary to minimize the likelihood of further prohibited take and ensure MMPA compliance. Lamont-Doherty may not resume their activities until notified by us via letter, email, or telephone.

9. Reporting an Injured or Dead Marine Mammal With an Unknown Cause of Death

In the event that Lamont-Doherty discovers an injured or dead marine mammal, and the lead visual observer 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 we describe in the next paragraph), the Observatory will immediately report the incident to the Chief, Permits and Conservation Division, Office of Protected Resources, NMFS, at 301-427-8401 and/or by email. The report must include the same information identified in the paragraph above this section. Activities may continue while NMFS reviews the circumstances of the incident. NMFS would work with Lamont-Doherty to determine whether modifications in the activities are appropriate.

10. Reporting an Injured or Dead Marine Mammal Unrelated to the Activities

In the event that Lamont-Doherty discovers an injured or dead marine mammal, and the lead visual observer determines that the injury or death is not associated with or related to the authorized activities (e.g., previously wounded animal, carcass with moderate to advanced decomposition, or scavenger damage), Lamont-Doherty would report the incident to the the Chief, Permits and Conservation Division, Office of Protected Resources, NMFS, at 301-427-8401 and/or by email, within 24 hours of the discovery. The Observatory would provide photographs or video footage (if available) or other documentation of the stranded animal sighting to NMFS.

11. Endangered Species Act Biological Opinion and Incidental Take Statement

Lamont-Doherty is required to comply with the Terms and Conditions of the Incidental Take Statement corresponding to the Endangered Species Act Biological Opinion issued to the National Science Foundation and NMFS' Office of Protected Resources, Permits and Conservation Division (attached). A copy of this Authorization and the Incidental Take Statement must be in the possession of all contractors and protected species observers operating under the authority of this Incidental Harassment Authorization.

Request for Public Comments

NMFS invites comments on our analysis, the draft authorization, and any other aspect of the Notice of proposed Authorization for Lamont-Doherty's activities. Please include any supporting data or literature citations with your comments to help inform our final decision on Lamont-Doherty's request for an application.