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Small Takes of Marine Mammals Incidental to Specified Activities; Marine Geophysical Survey of the Western Canada Basin, Chukchi Borderland and Mendeleev Ridge, Arctic Ocean, July-August, 2006
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[Federal Register: May 15, 2006 (Volume 71, Number 93)] [Notices] [Page 27997-28013] From the Federal Register Online via GPO Access [wais.access.gpo.gov] [DOCID:fr15my06-27] ----------------------------------------------------------------------- DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration [I.D. 050306A] Small Takes of Marine Mammals Incidental to Specified Activities; Marine Geophysical Survey of the Western Canada Basin, Chukchi Borderland and Mendeleev Ridge, Arctic Ocean, July-August, 2006 AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA), Commerce. ACTION: Notice; receipt of application and proposed incidental take authorization; request for comments. ----------------------------------------------------------------------- SUMMARY: NMFS has received an application from the University of Texas at Austin Institute for Geophysics (UTIG) for an Incidental Harassment Authorization (IHA) to take small numbers of marine mammals, by harassment, incidental to conducting a marine seismic survey in the Arctic Ocean from approximately July 15 - August 25, 2006. Pursuant to the Marine Mammal Protection Act (MMPA), NMFS is requesting comments on its proposal to issue an authorization to incidentally take, by harassment, small numbers of several species of marine mammals during the seismic survey. DATES: Comments and information must be received no later than June 14, 2006. ADDRESSES: Comments on the application should be addressed to Steve Leathery, Chief, Permits, Conservation and Education Division, Office of Protected Resources, National Marine Fisheries Service, 1315 East- West Highway, Silver Spring, MD 20910-3225. The mailbox address for providing email comments is PR1.050306A@noaa.gov. NMFS is not responsible for e-mail comments sent to addresses other than the one provided here. Comments sent via e-mail, including all attachments, must not exceed a 10-megabyte file size. A copy of the application containing a list of the references used in this document may be obtained by writing to the address specified above, telephoning the contact listed below (see FOR FURTHER INFORMATION CONTACT), or visiting the internet at: http://www.nmfs.noaa.gov/pr/permits/incidental.htm.Documents cited in this notice may be viewed, by appointment, during regular business hours, at the aforementioned address. FOR FURTHER INFORMATION CONTACT: Jolie Harrison, Office of Protected Resources, NMFS, (301) 713-2289, ext 166. SUPPLEMENTARY INFORMATION: Background Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 et seq.) direct the Secretary of Commerce to allow, upon request, the incidental, but not intentional, taking of marine mammals by U.S. citizens who engage in a specified activity (other than commercial fishing) within a specified geographical region if certain findings are made and either regulations are issued or, if the taking is limited to harassment, a notice of a proposed authorization is provided to the public for review. Authorization shall be granted if NMFS finds that the taking will have a negligible impact on the species or stock(s), will not have an unmitigable adverse impact on the availability of the species or stock(s) for subsistence uses, and that the permissible methods of taking and requirements pertaining to the mitigation, monitoring and reporting of such takings are set forth. NMFS has defined ``negligible impact'' in 50 CFR 216.103 as ``...an impact resulting from the specified activity that cannot be reasonably expected to, and is not reasonably likely to, adversely affect the species or stock through effects on annual rates of recruitment or survival.'' Section 101(a)(5)(D) of the MMPA established an expedited process by which citizens of the United States can apply for an authorization to incidentally take small numbers of marine mammals by harassment. Except with respect to certain activities not pertinent here, the MMPA defines ``harassment'' as: any act of pursuit, torment, or annoyance which (i) has the potential to injure a marine mammal or marine mammal stock in the wild [Level A harassment]; or (ii) has the potential to disturb a marine mammal or marine mammal stock in the wild by causing disruption of behavioral patterns, including, but not limited to, migration, breathing, nursing, breeding, feeding, or sheltering [Level B harassment]. Section 101(a)(5)(D) establishes a 45-day time limit for NMFS review of an application followed by a 30-day public notice and comment period on any proposed authorizations for the incidental harassment of marine mammals. Within 45 days of the close of the comment period, NMFS must either issue or deny issuance of the authorization. Summary of Request On March 8, 2006, NMFS received an application from UTIG for the taking, by [[Page 27998]] harassment, of several species of marine mammals incidental to conducting, with research funding from the National Science Foundation (NSF), a marine seismic survey in the Western Canada Basin, Chukchi Borderland and Mendeleev Ridge of the Arctic Ocean during July through August, 2006. The seismic survey will be operated in conjunction with a sediment coring project, which will obtain data regarding crustal structure. The purpose of the proposed study is to collect seismic reflection and refraction data and sediment cores that reveal the crustal structure and composition of submarine plateaus in the western Amerasia Basin in the Arctic Ocean. Past studies have led many researchers to support the idea that the Amerasia Basin opened about a pivot point near the Mackenzie Delta. However, the crustal character of the Chukchi Borderlands could determine whether that scenario is correct, or whether more complicated tectonic scenarios must be devised to explain the presence of the Amerasia Basin. These data will assist in the determination of the tectonic evolution of the Amerasia Basin and Canada Basin which is fundamental to such basic concerns as sea level fluctuations and paleoclimate in the Mesozoic era. Description of the Activity The Healy, a U.S. Coast Guard (USCG) Cutter ice-breaker, will rendezvous with the science party off Barrow on or around 15 July. The Healy will then sail north and arrive at the beginning of the seismic survey, which will start >150 km (93 mi) north of Barrow. The cruise will last for approximately 40 days, and it is estimated that the total seismic survey time will be approximately 30 days depending on ice conditions. Seismic survey work is scheduled to terminate west of Barrow about 25 August. The vessel will then sail south to Nome where the science party will disembark. The seismic survey and coring activities will take place in the Arctic Ocean. The overall area within which the seismic survey will occur is located approximately between 71[deg]36' and 79[deg]25' N., and between 151[deg]57' E. and 177[deg]24' E. The bulk of the seismic survey will not be conducted in any country's territorial waters. The survey will occur within the Exclusive Economic Zone (EEZ) of the U.S. for approximately 563 km. The Healy will use a portable Multi-Channel Seismic (MCS) system to conduct the seismic survey. A cluster of eight airguns will be used as the energy source during most of the cruise, especially in deep water areas. The airgun array will have four 500-in\3\ Bolt airguns and four 210-in\3\ G. guns for a total discharge volume of 2840 in\3\. In shallow water, occurring during the first and last portions of the cruise, a four 105 in\3\ GI gun array with a total discharge volume of 420 in\3\ will be used. Other sound sources (see below) will also be employed during the cruise. The seismic operations during the survey will be used to obtain information on the history of the ridges and basins that make up the Arctic Ocean. The Healy will also tow a hydrophone streamer 100-150 m (328-492 ft) behind the ship, depending on ice conditions. The hydrophone streamer will be up to 200 m (656 ft) long. As the source operates along the survey lines, the hydrophone receiving system will receive and record the returning acoustic signals. In addition to the hydrophone streamer, sea ice seismometers (SIS) will be deployed on ice floes ahead of the ship using a vessel-based helicopter, and then retrieved from behind the ship once it has passed the SIS locations. SISs will be deployed as much as 120 km (74 mi) ahead of the ship, and recovered when as much as 120 km (74 mi) behind the ship. The seismometers will be placed on top of ice floes with a hydrophone lowered into the water through a small hole drilled in the ice. These instruments will allow seismic refraction data to be collected in the heavily ice-covered waters of the region. The program will consist of a total of approximately 3625 km (2252 mi) of surveys, not including transits when the airguns are not operating, plus scientific coring at least seven locations. Water depths within the study area are 40-3858 m (131-12,657 ft). Little more than 8 percent of the survey (approximately 300 km (186 mi)) will occur in water depths < 100 m (328 ft), 23 percent of the survey (approximately 838 km (520 mi)) will be conducted in water 100-1000 m (328-3280 ft) deep, and most (69 percent) of the survey (approximately 2486 km (1,544 mi)) will occur in water deeper than 1000 m (3280 ft). There will be additional seismic operations associated with airgun testing, start up, and repeat coverage of any areas where initial data quality is sub-standard. In addition to the airgun array, a multibeam sonar and sub-bottom profiler will be used during the seismic profiling and continuously when underway. A pinger may be used during coring to help direct the core bit. The coring operations will be conducted in conjunction with the seismic study from the Healy. Seismic operations will be suspended while the USCG Healy is on site for coring. Several more coring sites may be identified and sampled depending on the ability to deploy SISs given ice and weather conditions. The plan is to extract one core from six of the seven identified sample locations along the seismic survey, and two cores at the last site on the Chukchi Cap. The coring system to be used is a piston corer that is lowered to the sea floor via a deep sea winch. Coring is expected to occur in 400-4000-m (1,312-13,120-ft) water depths. The piston corer recovers a sample in PVC tubes of 10 cm (3.9-in) diameter. Most of the cores will be approximately (approximately) 5-10 m long (16.4-32.8 ft); maximum possible length will be approximately 24 m (79 ft). The core is designed to leave nothing in the ocean after recovery. Vessel Specifications The Healy has a length of 128 m (420 ft), a beam of 25 m (82 ft), and a full load draft of 8.9 m (29 ft). The Healy iscapable of traveling at 5.6 km/h (3 knots) through 1.4 m (4.6 ft) of ice. A ``Central Power Plant'', four Sultzer 12Z AU40S diesel generators, provides electric power for propulsion and ship's services through a 60 Hz, 3-phase common bus distribution system. Propulsion power is provided by two electric AC Synchronous, 11.2 MW drive motors, fed from the common bus through a Cycloconverter system, that turn two fixed- pitch, four-bladed propellers. The operation speed during seismic acquisition is expected to be approximately 6.5 km/h (3.5 knots). When not towing seismic survey gear or breaking ice, the Healy cruises at 22 km/h (12 knots) and has a maximum speed of 31.5 km/h (17 knots). It has a normal operating range of about 29,650 km (18,423 mi) at 23.2 km/hr (12.5 knots). Seismic Source Description A portable MCS system will be installed on the Healy for this cruise. The source vessel will tow along predetermined lines one of two different airgun arrays (an 8-airgun array with a total discharge volume of 2840 in\3\ or a four GI gun array with a total discharge volume of 420 in3), as well as a hydrophone streamer. Seismic pulses will be emitted at intervals of approximately 60 s and recorded at a 2 ms sampling rate. The 60-second spacing corresponds to a shot interval of approximately 120 m (394 t) at the anticipated typical cruise speed. As the airgun array is towed along the survey line, the towed hydrophone array receives the reflected signals and transfers the data to the on-board [[Page 27999]] processing system. The SISs will store returning signals on an internal datalogger and also relay them in real-time to the Healy via a radio transmitter, where they will be recorded and processed. The 8-airgun array will be configured as a four-G. gun cluster with a total discharge volume of 840 in\3\ and a four Bolt airgun cluster with a total discharge volume of 2000 in\3\. The source output is from 246-253 dB re 1 microPa m. The two clusters are four meters apart. The clusters will be operated simultaneously for a total discharge volume of 2840 in\3\. The 4-GI gun array will be configured the same as the four G. gun portion of the 8-airgun array. The energy source (source level 239-245 dB re 1 microPa m) will be towed as close to the stern as possible to minimize ice interference. The 8-airgun array will be towed below a depressor bird at a depth of 7-20 m (23-66 ft) depending on ice conditions; the preferred depth is 8-10 m (26-33 ft). The highest sound level measurable at any location in the water from the airgun arrays would be slightly less than the nominal source level because the actual source is a distributed source rather than a point source. The depth at which the source is towed has a major impact on the maximum near-field output, and on the shape of its frequency spectrum. In this case, the source is expected to be towed at a relatively deep depth of up to 9 m (30 ft). The rms (root mean square) received sound levels that are used as impact criteria for marine mammals are not directly comparable to the peak or peak-to-peak values normally used to characterize source levels of airguns. The measurement units used to describe airgun sources, peak or peak-to-peak dB, are always higher than the rms dB referred to in much of the biological literature. A measured received level of 160 dB rms in the far field would typically correspond to a peak measurement of about 170 to 172 dB, and to a peak-to-peak measurement of about 176 to 178 decibels, as measured for the same pulse received at the same location (Greene, 1997; McCauley et al., 1998, 2000). The precise difference between rms and peak or peak-to-peak values for a given pulse depends on the frequency content and duration of the pulse, among other factors. However, the rms level is always lower than the peak or peak-to-peak level for an airgun-type source. Additional discussion of the characteristics of airgun pulses is included in Appendix A of UTIG's application. Safety Radii NMFS has determined that for acoustic effects, using established acoustic thresholds in combination with corresponding safety radii is the most effective way to consistently both apply measures to avoid or minimize the impacts of an action and to quantitatively estimate the effects of an action. NMFS believes that cetaceans and pinnipeds should not be exposed to pulsed underwater noise at received levels exceeding, respectively, 180 and 190 dB re 1 microPa (rms) to avoid permanent physiological damage (Level A Harassment). NMFS also assumes that cetaceans or pinnipeds exposed to levels exceeding 160 dB re 1 microPa (rms) experience Level B Harassment. Thresholds are used in two ways: (1) To establish a mitigation shut-down or power down zone, i.e., if an animal enters an area calculated to be ensonified above the level of an established threshold, a sound source is powered down or shut down; and (2) to calculate take, in that a model may be used to calculate the area around the sound source that will be ensonified to that level or above, then, based on the estimated density of animals and the distance that the sound source moves, NMFS can estimate the number of marine mammals that may be ``taken''. In order to implement shut-down zones, or to estimate how many animals may potentially be exposed to a particular sound level using the acoustic thresholds described above, it is necessary to understand how sound will propagate in a particular situation. Models may be used to estimate at what distance from the sound source the water will be ensonified to a particular level. Safety radii represent the estimated distance from the sound source at which the received level of sound would correspond to the acoustic thresholds of 190, 180, and 160 dB. Many models have been field tested in the water. Field verification has shown that some of the predictions are close to being accurate, an some are not. UTIG proposed to base the safety radii for the Healy cruise on a model created by the Lamont-Doherty Earth Observatory and field tested in the Gulf of Mexico. UTIG has further proposed to enlarge some of the safety radii that relate to shut-down zones to provide further protection for marine mammals that may be in the area during seismic operations. The model utilized by UTIG to develop their safety radii is described below. Safety Radii Proposed by UTIG Received sound fields have been modeled by Lamont-Doherty Earth Observatory (L-DEO) for the 8-airgun and 4-GI gun arrays that will be used during this survey. Predicted sound fields were modeled using sound exposure level (SEL) units (dB re 1 microPa\2\ s), because a model based on those units tends to produce more stable output when dealing with mixed-gun arrays like the one to be used during this survey. The predicted SEL values can be converted to rms received pressure levels, in dB re 1 microPa (as used in NMFS' impact criteria for pulsed sounds) by adding approximately 15 dB to the SEL value (Greene, 1997; McCauley et al., 1998, 2000). The rms pressure is an average over the pulse duration. This is the measure commonly used in studies of marine mammal reactions to airgun sounds, and in NMFS guidelines concerning levels above which ``taking'' might occur. The rms level of a seismic pulse is typically about 10 dB less than its peak level. The empirical data concerning 190, 180, and 160 dB (rms) distances in deep and shallow water acquired for various airgun array configurations during the acoustic verification study conducted by L- DEO in the northern Gulf of Mexico. Tolstoy et al., (2004a,b) demonstrate that L-DEO's model tends to overestimate the distances applied in deep water. The proposed study area will occur mainly in water approximately 40-3858 m (131-12,657 ft) deep, with only approximately 8 percent of the survey lines in shallow (< 100 m (< 328 ft)) water and approximately 23 percent of the trackline in intermediate water depths (100-1000 m (328-3,280 ft)). The calibration- study results showed that radii around the airguns where the received level would be 180 dB re 1 microPa (rms), the safety criterion applicable to cetaceans (NMFS 2000), vary with water depth. Similar depth-related variation is likely in the 190-dB distances applicable to pinnipeds. UTIG has applied the empirical data collected during the Gulf of Mexico verification study to the L-DEO model in the manner described below to develop the safety radii listed in Table 1: ? The empirical data indicate that, for deep water (>1000 m), the L-DEO model tends to overestimate the received sound levels at a given distance (Tolstoy et al., 2004a,b). However, to be precautionary pending acquisition of additional empirical data, it is proposed that safety radii during airgun operations in deep water will be the [[Page 28000]] values predicted by L-DEO's modeling, after conversion from SEL to rms (Table 1). ? Empirical measurements were not conducted for intermediate depths (100-1000 m). On the expectation that results would be intermediate between those from shallow and deep water, a 1.5 correction factor is applied to the estimates provided by the model for deep water situations (as noted before, NSF is recalculating the numbers using a more conservative, or larger, correction factor). ? Empirical measurements were not made for the 4 GI guns that will be employed during the proposed survey in shallow water (< 100 m). (The 8-airgun array will not be used in shallow water.) The empirical data on operations of two 105 in\3\ GI guns in shallow water showed that modeled values underestimated the distance to the actual 160 dB sound level radii in shallow water by a factor of approximately 3 (Tolstoy et al., 2004b). Sound level measurements for the 2 GI guns were not available for distances < 0.5 km (.31 mi)(from the source. The radii estimated here for the 4 GI guns operating in shallow water are derived from the L-DEO model, with the same adjustments for depth- related differences between modeled and measured sound levels as were used for 2 GI guns in earlier applications. Correction factors for the different sound level radii are approximately 12x the model estimate for the 190 dB radius in shallow water, approximately 7x for the 180 dB radius and approximately 4x for the 170 dB radius [Tolstoy 2004a,b]). As mentioned above, UTIG has further proposed expanded safety radii, as they apply to the shutdown zones for marine mammals, and these are indicated by parentheses in Table 1. [GRAPHIC] [TIFF OMITTED] TN15MY06.036 Other Acoustic Devices Along with the airgun operations, additional acoustical systems will be operated during much of or the entire cruise. The ocean floor will be mapped with a multibeam sonar, and a sub-bottom profiler will be used. These two systems are commonly operated simultaneously with an airgun system. An acoustic Doppler current profiler will also be used through the course of the project, as well as a pinger. Multibeam Echosounder (SeaBeam 2112) A SeaBeam 2112 multibeam 12 kHz bathymetric sonar system will be used on the Healy, with a maximum source output of 237 dB re 1 microPa at one meter. The transmit frequency is a very narrow band, less than 200 Hz, and centered at 12 kHz. Pulse lengths range from less than one millisecond to 12 ms. The transmit interval ranges from 1.5 s to 20 s, depending on the water depth, and is longer in deeper water. The SeaBeam system consists of a set of underhull projectors and hydrophones. The transmitted beam is narrow (approximately 2[deg]) in the fore-aft direction but broad (approximately 132[deg]) in the cross- track direction. The system combines this transmitted beam with the input from an array of receiving hydrophones oriented perpendicular to the array of source transducers, and calculates bathymetric data (sea floor depth and some indications about the character of the seafloor) with an effective 2[deg] by 2[deg] foot print on the seafloor. The SeaBeam 2112 [[Page 28001]] system on the Healy produces a useable swath width of slightly more than 2 times the water depth. This is narrower than normal because of the ice-protection features incorporated into the system on the Healy. Hydrographic Sub-bottom Profiler (Knudsen 320BR) The Knudsen 320BR will provide information on sedimentary layering, down to between 20 and 70 m, depending on bottom type and slope. It will be operated with the multibeam bathymetric sonar system that will simultaneously map the bottom topography. The Knudsen 320BR sub-bottom profiler is a dual-frequency system with operating frequencies of 3.5 and 12 kHz: Low frequency - Maximum output power into the transducer array, as wired on the Healy (125 ohms), at 3.5 kHz is approximately 6000 watts (electrical), which results in a maximum source level of 221 dB re 1 microPa at 1 m downward. Pulse lengths range from 1.5 to 24 ms with a bandwidth of 3 kHz (FM sweep from 3 kHz to 6 kHz). The repetition rate is range dependent, but the maximum is a 1-percent duty cycle. Typical repetition rate is between 1/2 second (in shallow water) to 8 seconds in deep water. High frequency - The Knudsen 320BR is capable of operating at 12 kHz; but the higher frequency is rarely used because it interferes with the SeaBeam 2112 multibeam sonar, which also operates at 12 kHz. The calculated maximum source level (downward) is 215 dB re 1 microPa at 1 m (3.28 ft). The pulse duration is typically 1.5 to 5 ms with the same limitations and typical characteristics as the low frequency channel. A single 12 kHz transducer and one 3.5 kHz, low frequency (sub- bottom) transducer array, consisting of 16 elements in a 4 by 4 array will be used for the Knudsen 320BR. The 12 kHz transducer (TC-12/34) emits a conical beam with a width of 30[deg] and the 3.5 kHz transducer (TR109) emits a conical beam with a width of 26[deg]. 12-kHz Pinger (Benthos 2216) A Benthos 12-kHz pinger may be used during coring operations, to monitor the depth of the corer relative to the sea floor. The pinger is a battery-powered acoustic beacon that is attached to the coring mechanism. The pinger produces an omnidirectional 12 kHz signal with a source output of approximately 192 dB re 1 microPa m at a one pulse per second rate. The pinger produces a single pulse of 0.5, 2 or 10 ms duration (hardware selectable within the unit) every second. Acoustic Doppler Current Profiler (150 kHz) The 150 kHz acoustic Doppler current profiler (ADCP ) has a minimum ping rate of 0.65 ms. There are four beam sectors, and each beamwidth is 3[deg]. The pointing angle for each beam is 30[deg] off from vertical with one each to port, starboard, forward and aft. The four beams do not overlap. The 150 kHz ADCP's maximum depth range is 300 m. Acoustic Doppler Current Profiler (RD Instruments Ocean Surveyor 75) The Ocean Surveyor 75 is an ADCP operating at a frequency of 75 kHz, producing a ping every 1.4 s. The system is a four-beam phased array with a beam angle of 30[deg]. Each beam has a width of 4[deg], and there is no overlap. Maximum output power is 1 kW with a maximum depth range of 700 m (2,297 ft). Description of Habitat and Marine Mammals Affected by the Activity A detailed description of the Beaufort and Chukchi sea ecosystems and their associated marine mammals can be found in several documents (Corps of Engineers, 1999; NMFS, 1999; Minerals Management Service (MMS), 2006, 1996 and 1992). MMS' Programmatic Environmental Assessment (PEA) - Arctic Ocean Outer Continental Shelf Seismic Surveys - 2006 may be viewed at: http://www.mms.gov/alaska/.