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USGS Open-File Report 03-474, G1-03-GM, Gas Hydrates Cruise Report, R/V Gyre, 1-14 May 2003, Northern Gulf of Mexico

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Appendix 3

(3) Submission to National Marine Fisheries "Request by the U.S. Geological Survey for an Incidental Harassment Authorization to conduct a survey in the Gulf of Mexico"

Request by the U.S. Geological Survey for an Incidental Harassment Authorization to conduct a survey in the Gulf of Mexico

F. Summary Request

The U.S. Geological Survey (USGS) hereby requests an Incidental Harassment Authorization from the National Marine Fisheries Service to allow the incidental harassment of marine mammals that may occur while collecting marine high-resolution seismic-reflection data offshore in the Gulf of Mexico. The data collected will be used to support an on going Gas-Hydrates study. Gas hydrates are methane-ice substances found at the sea floor and in shallow sub-bottom sediments on continental margins in water depths greater than about 500 m. The USGS research program is investigating the occurrence and distribution of naturally occurring marine gas hydrates in the Gulf of Mexico in order to understand the hazard they pose to deep-water drilling and the potential they offer as an energy resource. As part of this study, we wish to acquire high-resolution seismic reflection data to better image and therefore understand the geologic structure and stratigraphy in areas where gas hydrate has been recovered by seafloor coring programs and where an industry-funded research well will be drilled in early 2004.

The five seismic sources to be utilized under this request are a Huntec™ boomer (peak frequency of 4.5 kHz); Edgetech sub-bottom profiler (peak frequency of 5.75 kHz), Benthos SIS-1000 side scan sonar (operating frequency of 100khz) and sub-bottom profiler (operating at a swept frequency of 2khz to 5khz), 15 in3 water gun (peak frequencies less than 500 Hz) and a 35-in3 Generator-Injector (GI) gun (peak frequencies less than 500 Hz). This study should result in no taking of marine mammals. The likelihood of incidental harassment, while not impossible, is unlikely given the frequencies and low energy levels of the sources. The USGS proposes to have trained mammal observers on board the research vessel and to abide by zones of impact set at 20 m, 20 m, 20 m, 30 m, and 30 m respectively (for the five seismic sources) for mysticetes and odontocetes. Work will be conducted 24 hours a day.

Contacts:Patrick Hart (Primary Investigator)
U.S. Geological Survey
Coastal and Marine Geology Team, MS 999
345 Middlefield Rd. Menlo Park, Calif. 94025
hart@usgs.gov
tel (650) 329-5160
fax (650) 329-5190

Deborah Hutchinson (Primary Investigator)
U.S. Geological Survey384 Woods Hole Rd.
Woods Hole, Ma. 02543-1598
dhutchinson@usgs.gov
tel (650) 457-2263
fax(508) 457-2310

David Hogg
U.S. Geological Survey
599 Seaport Blvd.
Redwood City, Calif. 94063
dhogg@usgs.gov
tel (650) 329-5864
fax (650) 365-9841

(1) A detailed description of the specific activity or class of activities that can be expected to result in incidental taking of marine mammals;

The U.S. Geological Survey proposes to conduct a high-resolution seismic-reflection survey offshore in the Gulf of Mexico for approximately fourteen days at the beginning of May 2003. The seismic reflection data will be collected using three basic systems:

1) Huntec™ boomer sound source to collect high-resolution seismic-reflection data of the sub-sea floor;

2) Edgetech 512I sub-bottom profiler to collect high-resolution seismic-reflection data of the sub-sea floor;

3) Data Sonics SIS-1000 side scan sonar with a sub-bottom profiler; and

4) A high-resolution multi-channel system for which the primary source will be a 15-in3 water gun or 35-in3 GI gun. A 250-m-long hydrophone streamer is used for the multi-channel system.

The high-resolution Huntec™ boomer system uses an electrically powered sound source that is towed behind the ship at depths between 30 m and 160 m below the sea surface. The hydrophone arrays for listening are attached to the tow vehicle that houses the sound source. We plan to use the Huntec™ primarily in water depths greater than 300 m. The system is triggered at 0.5 to 1.25 second intervals, depending upon the source tow depth. The sound pressure level (SPL) for this unit is 205 dB µ 1 µPa-m RMS. The output-sound bandwidth is 0.5 kHz to 8 kHz, with the main peak at 4.5 kHz. The estimated zone of impact, including absorption calculations (Richardson et al., 1995, p. 73) using 4.5 kHz as the peak frequency at 160 dB is 175 meters and at 180 dB is 17 meters.

The Edgetech 512I Chirp is a high resolution seismic system. The system is towed either at the water surface or slightly submerged, depending on the application and water depth. The 512I has a sound pressure level (SPL) of 198 dB µ 1µ Pa-m RMS. It has a frequency range of 500hz to 12kHz with pulse widths from 5 ms to 50 ms depending on the application. Using the center frequency of 5.75 kHz the estimated zone of impact at 160 dB including absorption calculations (Richardson et al., 1995, p.73) is 75 meters and at 180 dB is 8 meters.

The SIS-1000 is a chirp side scan sonar and sub-bottom profiler. It is towed behind the ship at depths of 1 to 700 meters depending on the depth of the water. The side scan frequency is a 100-khz band swept FM and the sub-bottom profiler is a 2kHz to 5kHz swept FM band. The side scan system measures the return time and the intensity of echoes to create a high-resolution image of the sea floor similar to an air photo on land. The sub-bottom profiler is another tool used to collect high-resolution data of the sub-sea floor. The sub-bottom profiler is synchronous with side scan.

The side scan has a sound pressure level (SPL) of 225 dB µ 1m Pa-m RMS that radiates at .5° horizontal at a 70°'s vertical angle. The estimated zone of impact using absorption calculations (Richardson et al., 1995, p.73) for 160 dB is 375 meters and 180 dB is 105 meters. This sound is a very focused beam and not a 360° pattern. The sub-bottom profiler has a sound pressure level of 207dB µ 1mPa-m RMS. Using a center frequency of 4.5 kHz the estimated zone of impact using absorption calculations (Richardson et al., 1995, p. 73) for 160 dB is 250 meters and 180 dB is 25 meters. This is a 45° conical beam looking downward from the tow fish.

The multichannel system has two potential pneumatic sources: 15-in3 water gun or 35-in3 GI gun. The larger source, the 35-in3 GI gun is a special type of small air gun called a generator-injector, or GI gun (trademark of Seismic Systems, Inc., Houston, TX). This is a dual chamber gun that will have inserts installed to reduce it from a 35-in3 to a 24-in3 gun. This type of air gun consists of two small air guns within a single steel body. The two small air guns are fired sequentially, with the precise timing required to nullify the bubble oscillations that typify sound pulses from a single air gun of common type. These oscillations impede detailed analysis of the sub-surface. For arrays consisting of many air guns, bubble oscillations are cancelled by careful selection of air gun sizes. The GI gun is a mini-array that is carefully adjusted to achieve the desired bubble cancellation. Air guns and GI guns with similar chamber sizes have similar peak output pressures. The GI gun for this survey has two chambers of equal size-24-in3 and the gun will be fired every 10 seconds. Compressed air delivered to the GI gun will have a pressure between 2000 and 3000 psi. The gun will be towed 5 meters behind the vessel and suspended from a float to maintain a depth of about 1 m.

The manufacturer's literature indicates that a GI gun of the size we will use has a sound-pressure level (SPL) of about 208 dB µ 1 µPa-m RMS. The GI gun's output sound pulse has a duration of about 10 ms. The amplitude spectrum of this pulse, as shown by the manufacturer's data, indicates that most of the sound energy is at frequencies below 500 Hz. Field measurements by USGS personnel indicates that the GI gun outputs low sound amplitudes at frequencies above 500 Hz. Thus high-amplitude sound from this source is at frequencies that are outside the main hearing band of odontocetes and pinnipeds (Richardson et al. 1995, p. 205-240). Using a peak frequency of 500 Hz the estimated zone of impact at 160 dB including absorption calculations (Richardson et al.,1995, p.73) is 250 meters and at 180 dB is 25 meters.

The smaller sound source for the multi-channel system is a Type S15 T Water Gun manufactured by Seismic Systems Inc. This type of gun stores high pressure air in the air chambers that when fired, forces water that is stored in the water chamber out through four ports generating an acoustical signal of implosive type. The used air exhausts through two lateral pipes. The gun is towed from 0.5 meters to 3 meters deep and approximately 5 meters behind the ship. The system is operated with 3000 psi high pressure air. The water gun has a 15 cubic inch chamber and a peak frequency of less than 500 Hz (100 - 300 Hz) and will be fired at approximately 5 second intervals. Available information from the manufacturer for the small water gun is for firing at 1800 psi, somewhat lower than our proposed firing of 3000psi. At the lower pressure, the water gun has a peak frequency of 100-500 Hz, maximum energy at 190-200 Hz, a signal length of about 0.025 s (25ms), and a sound pressure level of 204 dB µ 1mPa-m RMS. Using a frequency of 200 Hz the estimated zone of impact using absorption calculations (Richardson et al., 1995, p. 73) for 160dB is 170 meters and 180dB is 15 meters. The higher pressure will slightly increase the maximum energy, and shift the peak frequencies slightly higher, but not above 500Hz (Hutchinson, D.R., and Detrick, R.S., 1984, Water gun vs Air gun: a comparison: Marine Geophysical Researches, v. 6,p. 295-310).

In 1994, the Northeast NMFS approved the use of the 15 in3 water gun for profiling in Stellwagen Bank National Marine Sanctuary, a region where Right Whales, an endangered species, are often found.

(2) The date(s) and duration of such activity and the specific geographical region where it will occur; The work is planned for approximately 14 days starting about the 1st of May and ending about the 14th of May 2003. The vessel will be the research vessel Gyre. The primary work area is between longitude 93 W and 89 W south of the 300 meter contour and north of the 2500 meter contour. We will be working 24 hours a day 7 days a week.

(3) The species and numbers of marine mammals likely to be found within the activity area;

Species of marine mammals Estimated Population Strategic Status Notes (see below)
Sperm Whale Northern Gulf of Mexico Stock 530 YES b,f
Dwarf Sperm Whale Northern Gulf of Mexico Stock 547 YES a,b
Pygmy Sperm Whale Northern Gulf of Mexico Stock 547 YES a,b
Byrde’s Whale Northern Gulf of Mexico Stock 35 NO b
Cuvier’s Beaked Whale Northern Gulf of Mexico Stock 30 NO b
Gervais’ Beaked Whale Northern Gulf of Mexico Stock ? NO b,c
Bottlenose Dolphin Northern Gulf of Mexico Stock 4191 NO d
Bottlenose Dolphin Eastern Gulf of Mexico Coastal Stock 9912 NO d
Atlantic Spotted Dolphin Northern Gulf of Mexico Stock 3213 NO b,e
Pantropical Spotted Dolphin Northern Gulf of Mexico Stock 31320 NO b
Striped Dolphin Northern Gulf of Mexico Stock 4858 NO b
Spinner Dolphin Northern Gulf of Mexico Stock 6316 NO b
Rough-Toothed Dolphin Northern Gulf of Mexico Stock 852 NO b
Clymene Dolphin Northern Gulf of Mexico Stock 5571 NO b
Frasers Dolphin Northern Gulf of Mexico Stock 127 NO b
Killer Whale Northern Gulf of Mexico Stock 277 NO b
False Killer Whale Northern Gulf of Mexico Stock 381 NO b
Pygmy Killer Whale Northern Gulf of Mexico Stock 518 NO b
Melon-Headed Whale Northern Gulf of Mexico Stock 3965 NO b
Risso’s Dolphin Northern Gulf of Mexico Stock 2749 NO b
Short-Finned Pilot Whale Northern Gulf of Mexico Stock 353 YES b

Notes

a) Estimates of specific species of sperm whales abundance cannot be provided due to uncertainty of species identification at sea.

b) Source: Hansen et al. (1995) as reported in Waring et al.( 2001)

c) Estimates may also include an unknown number of Cuvier beaked whales and abundance of Gervais beaked whale cannot be estimated due to uncertainty of species identification at sea.

d) Source: Blaylock and Hoggard (1994) as reported in Waring et al. (2001)

e) This could be an underestimate and should be considered a partial stock estimate because the continental shelf areas were not generally covered by either vessel or GulfCet aerial surveys.

f) This species is listed as endangered under the Endangered Species act (ESA).

(4) A description of the status, distribution, and seasonal distribution (when applicable) of the affected species or stocks of marine mammals likely to be affected by such activities;

Sperm Whale, Northern Gulf of Mexico Stock
Sperm whales are found throughout the world's oceans in deep waters from between about 60° N and 60° S latitudes (Leatherwood and Reeves 1983; Rice 1989). There has been speculation, based on year round occurrence of strandings, opportunistic sightings, and whaling catches, that sperm whales in the Gulf of Mexico may constitute a distinct stock (Schmidly 1981), but there is no information on stock differentiation. Seasonal aerial surveys confirm that sperm whales are present in the northern Gulf of Mexico in all seasons, but sightings are more common during the summer months (Mullin et al. 1991; Davis et al., in preparation). Seasonal GulfCet aerial surveys done between 1991 and 1994 showed an average estimated abundance of sperm whales for all surveys combined was 530 coefficient of variation (CV) = 0.31 (Hansen et al. 1995). This species is listed as endangered under the Endangered Species Act (ESA).

Dwarf Sperm Whale, Northern Gulf of Mexico Stock
The Dwarf sperm whale appears to be distributed worldwide in temperate to tropical waters (Caldwell and Caldwell 1989). Sightings of these animals in the northern Gulf of Mexico occur primarily along the continental shelf edge and over the deeper waters off the continental shelf (Mullin et al. 1991; Southeast Fisheries science Center, SEFSC, unpublished data). Dwarf sperm whales and pygmy sperm whales are difficult to distinguish and sightings of either species are often categorized as Kogia sp. Pygmy and dwarf sperm whales have been sighted in the northwestern Gulf of Mexico in waters 1000 m deep, on average (Davis et al. 1998). However, these authors cautioned that inferences on preferred bottom depths should await surveys for the entire Gulf of Mexico. Estimated average abundance of Kogia sp. by surveys done from 1991 through 1994 is 547 (Hansen et al. 1995). Estimates of specific species of sperm whales abundance cannot be provided due to uncertainty of species identification at sea. This species is not listed under the Endangered Species Act.

Pygmy Sperm Whale, Northern Gulf of Mexico Stock
The Pygmy sperm whale appears to be distributed worldwide in temperate to tropical waters (Caldwell and Caldwell 1989). Sightings of these animals in the northern Gulf of Mexico occur primarily along the continental shelf edge and over the deeper waters off the continental shelf (Mullin et al. 1991; Southeast Fisheries science Center, SEFSC, unpublished data). Dwarf sperm whales and pygmy sperm whales are difficult to distinguish and sightings of either species are often categorized as Kogia sp. Pygmy and dwarf sperm whales have been sighted in the northwestern Gulf of Mexico in waters 1000 m deep, on average (Davis et al. 1998). However, these authors cautioned that inferences on preferred bottom depths should await surveys for the entire Gulf of Mexico. Estimated average abundance of Kogia sp. by surveys done from 1991 through 1994 is 547 (Hansen et al. 1995). Estimates of specific species of sperm whales abundance cannot be provided due to uncertainty of species identification at sea. This species is not listed under the Endangered Species Act.

Byrde's Whale, Northern Gulf of Mexico Stock
Brydes's whales are considered the tropical and subtropical baleen whale of the worlds oceans. It is postulated that the Bryde's whales found in the Gulf of Mexico may represent a resident stock (Schmidly 1981; Leatherwood and Reeves 1983), but there is no information on stock differentiation. Most sightings of Bryde's whales have occurred during the spring-summer months Hansen et al. 1995; Davis et al. in preparation), but strandings have occurred throughout the year (Jefferson et al. 1992). Data collected on vessel surveys during 1991 - 1994 spring-summer in the northern Gulf of Mexico was used to estimate an average abundance for all surveys as 35 (CV=1.10) (Hansen et al. 1995) and was based on three sightings all of which occurred in 1991. This species is not listed under the Endangered Species Act.

Cuvier's Beaked Whale , Northern Gulf of Mexico Stock
Cuvier's beaked whales are distributed throughout the world's oceans except for the polar regions (Leatherwood and Reeves 1983; Heyning 1989). Beaked whales were seen in all seasons during recent seasonal GulfCet aerial surveys of the northern Gulf of Mexico (Davis et al., in preparation). Some of the aerial sightings may have included Curvier's beaked whale, but identification of beaked whale species from aerial surveys is problematic. Data collected on vessel surveys during 1991 - 1994 spring-summer in the northern Gulf of Mexico was used to estimate an average abundance for all surveys as 30 (CV=0.50) (Hansen et al. 1995). The estimated abundance of Curvier's beaked whales is 30 (CV=0.50) (Hansen et al. 1995).

Gervais' Beaked Whale, Northern Gulf of Mexico Stock
Beaked whales were seen in all seasons during recent seasonal GulfCet aerial surveys of the northern Gulf of Mexico (Davis et al., in preparation). Abundance estimates of Gervais' beaked whales are uncertain due to species identification at sea. This species is not listed under the Endangered Species Act.

>Bottlenose Dolphin, Northern Gulf of Mexico Coastal Stock
The northern Gulf of Mexico coastal bottlenose dolphin stock has been defined for management purposes as those bottlenose dolphins occupying the nearshore coastal waters in the U.S. Gulf of Mexico from the Mississippi River mouth to approximately 84°W longitude, from shore, barrier islands, or presumes bay boundries to 9.3 km seaward of the 18.3 m isobath. The northern coastal stock area is characterized by temperate climate, barrier islands, sand beaches, coastal marshes and marsh islands, and has a relatively high level of fresh water input from rivers and streams. The abundance estimate is 4,191 dolphins with coefficient of variation (CV) = 0.21 (Blaylock and Hoggard 1994). This species is not listed as threatened or endangered under the Endangered Species Act.

Bottlenose Dolphin, Eastern Gulf of Mexico Coastal Stock
The eastern Gulf of Mexico coastal bottlenose dolphin stock has been defined for management purposes as the bottlenose dolphins occupying the area which extends from approximately 84° W Longitude to Key West, Florida from shore barrier islands, or presumed bay boundaries to 9.3 km seaward of the 18.3 m isobath. The eastern coastal stock area is temperate to subtropical in climate, is bordered by a mixture of coastal marshes, sand beaches, marsh and mangrove islands, and has an intermediate level of freshwater input. The abundance estimate is 9,912 dolphins with coefficient of variation (CV) =0.12. ). This species is not listed as threatened or endangered under the Endangered Species Act.

Atlantic Spotted Dolphin, Northern Gulf of Mexico Stock
The Atlantic spotted dolphin is endemic to the Atlantic Ocean in warm temperature to tropical waters (Perrin et al. 1987,1994). Sightings of this species are concentrated along the continental shelf edge and also occur over the continental shelf in northern Gulf of Mexico[ Fritts et al. 1983; Mullin et al. 1991; Southeast Fisheries Science Center (SEFSC) unpublished data]. Atlantic spotted dolphins were seen in all seasons during recent GulfCet aerial surveys of the northern Gulf of Mexico during 1993-1995 ( Davis et al., in preparation). An average abundance estimate for all surveys combined is 3,213 (CV = 0.44) (Hansen et al. 1995). This could be an underestimate and should be considered a partial stock estimate because the continental shelf areas were not generally covered by either vessel or GulfCet aerial surveys. This species is not listed under the Endangered Species Act.

Pantropical Spotted Dolphin, Northern Gulf of Mexico Stock
The Pantropical spotted dolphin is distributed worldwide in tropical and some sub-tropical oceans (Perrin et al. 1987; Perrin and Hohn 1994). Sightings of this species occurred over the deeper waters of the northern Gulf of Mexico, and rarely over the continental shelf or continental shelf edge [Mullin et al. 1991; Southeastern Fisheries Science Center (SEFSC) unpublished data].Pantropical spotted dolphins were seen in all seasons during recent seasonal GulfCet aerial surveys of the northern Gulf of Mexico during 1993-1995 (Davis et al., in preparation). An average abundance estimate for all surveys combined is 31,320 (CV = 0.20) (Hansen et al. 1995). This species is not listed under the Endangered Species Act.

Striped Dolphin, Northern Gulf of Mexico Stock
The striped dolphin is distributed worldwide in tropical to warm temperate oceanic waters (Leatherwood and Reeves 1983; Perrin et al. 1994). Sightings of these animals in the northern Gulf of Mexico occur primarily over the deeper waters off the continental shelf [ Mullin et al. 1991; Southeastern Fisheries Science Center (SEFSC) unpublished data]. Striped dolphins were seen in fall, winter, and spring during recent seasonal GulfCet aerial surveys of the northern Gulf of Mexico during 1993 - 1995 (Davis et al., in preparation). An average abundance estimate for all surveys combined is 4,858 (CV = 0.44) ( Hansen et al. 1995). This species is not listed under the Endangered Species Act.

Spinner Dolphin, Northern Gulf of Mexico Stock
The spinner dolphin is distributed worldwide in tropical to warm temperate waters in the world's oceans (Leatherwood and Reeves 1983; Perrin and Gilpatrick 1994). Sightings of these animals in the northern Gulf of Mexico occur primarily over the deeper waters off the continental shelf [ Southeastern Fisheries Science Center (SEFSC) unpublished data]. Spinner dolphins were seen in winter, spring and summer during recent seasonal GulfCet aerial surveys of the northern Gulf of Mexico during 1993 - 1995 (Davis et al., in preparation). An average abundance estimate for all surveys combined is 3,316(CV = 0.43) ( Hansen et al. 1995). This species is not listed under the Endangered Species Act.

The rough-toothed dolphin is distributed worldwide in tropical to warm temperate waters (Leatherwood and Reeves 1983; Miyazaki and Perrin 1994). Sightings of these animals in the northern Gulf of Mexico occur primarily over the deeper waters off the continental shelf [Southeastern Fisheries Science Center (SEFSC) unpublished data]. Rough-toothed dolphins were seen in all seasons during recent seasonal GulfCet aerial surveys of the northern Gulf of Mexico during 1993 - 1995 (Davis et al., in preparation). An average abundance estimate for all surveys combined is 852 (CV = 0.31) ( Hansen et al. 1995). This species is not listed under the Endangered Species Act.

Clymene Dolphin, Northern Gulf of Mexico Stock
The Clymene dolphin is distributed worldwide in tropical and sub-tropical waters of the Atlantic (Leatherwood and Reeves 1983; Perrin and Mead 1994). Sightings of these animals in the northern Gulf of Mexico occur primarily over the deeper waters off the continental shelf ( Mullin et al. 1994). Clymene dolphins were seen in the winter, spring and summer during recent seasonal GulfCet aerial surveys of the northern Gulf of Mexico during 1993 - 1995 (Davis et al., in preparation). An average abundance estimate for all surveys combined is 5,274(CV = 0.37) ( Hansen et al. 1995). This species is not listed under the Endangered Species Act.

Fraser's Dolphin, Northern Gulf of Mexico Stock
Fraser's dolphin is distributed worldwide in tropical waters (Perrin et al. 1994). Sightings of these animals in the northern Gulf of Mexico occur primarily over the deeper waters off the continental shelf ( Leatherwood et al. 1993). Fraser's dolphins have been observer recently in the northern Gulf of Mexico during the spring, summer, and fall ( Leatherwood et al. 1993), and also were seen in the winter during recent seasonal GulfCet aerial surveys of the northern Gulf of Mexico during 1993 - 1995 ( Davis et al. in preparation). An average abundance estimate for all vessel surveys combined is 127 (CV = 0.90) ( Hansen et al. 1995). This species is not listed under the Endangered Species Act.

Killer Whale, Northern Gulf of Mexico Stock
The killer whale is distributed worldwide from tropical to polar regions (Leatherwood and Reeves 1983). Sightings of these animals in the northern Gulf of Mexico occur primarily over the deeper waters off the continental shelf [ Southeast Fisheries Science Center (SEFSC) unpublished data]. Killer whales were seen only in the summer during recent seasonal GulfCet aerial surveys of the northern Gulf of Mexico during 1993 - 1995 (Davis et al., in preparation) and in the late spring during vessel surveys (SEFSC unpublished data). An average abundance estimate for all surveys combined is 277 (CV = 0.42) ( Hansen et al. 1995).

The false killer whale is distributed worldwide throught warm temperate and tropical oceans (Leatherwood and Reeves 1983). Sightings of this species in the northern Gulf of Mexico occur primarily over the deeper waters off the continental shelf [Southeast Fisheries Science Center (SEFSC) unpublished data]. False killer whales were seen only in the summer during recent seasonal GulfCet aerial surveys of the northern Gulf of mexico during 1993 - 1995 (Davis et al., in preparation) and in late spring during vessel surveys (NMFS unpublished data). An average abundance estimate for all surveys combined is 381 (CV = 0.62) ( Hansen et al. 1995). This species is not listed under the Endangered Species Act.

Pygmy Killer Whale, Northern Gulf of Mexico Stock
The pygmy killer whale is distributed worldwide in tropical and sub-tropical waters (Ross and Leatherwood 1994). Sightings of these animals in the northern Gulf of Mexico occur primarily over the deeper waters off the continental shelf [Southeast Fisheries Science Center (SEFSC) unpublished data]. Sightings of this category were documented in all seasons during recent seasonal GulfCet aerial surveys of the northern Gulf of Mexico during 1993 - 1995 (Davis et al., in preparation). An average abundance estimate for all surveys combined is 518 (CV = 0.81) ( Hansen et al. 1995). This species is not listed under the Endangered Species Act.

Melon-Headed Whale, Northern Gulf of Mexico Stock
The melon-headed whale appears to be distributed worldwide in tropical to sub-tropical waters (Perryman et al. 1994). Sightings of these animals in the northern Gulf of Mexico occur primarily over the deeper waters off the continental shelf (Mullin et al. 1994). Sightings of this category were documented in all seasons during recent seasonal GulfCet aerial surveys of he northern Gulf of Mexico during 1993 - 1995 (Davis et al., in preparation). An average abundance estimate for all surveys combined is 3,965 (CV = 0.39) ( Hansen et al. 1995). This species is not listed under the Endangered Species Act.

Risso's Dolphin, Northern Gulf of Mexico Stock
Risso's dolphin is distributed worldwide in tropical to warm waters (Leatherwood and Reeves 1983). Sightings of these animals in the northern Gulf of Mexico occur primarily along the continental shelf and continental slope (Mullin et al. 1991; Southeast Fisheries Science Center, SEFSC, unpublished data). Risso's dolphin were seen in all seasons during recent seasonal GulfCet aerial surveys of the northern Gulf of Mexico during 1993-1995 (Davis et al., in preparation) and in the late spring during vessel surveys (SEFSC, unpublished data). An average abundance estimate for all surveys combined is 2,749 (CV = 0.27) ( Hansen et al. 1995). This species is not listed under the Endangered Species Act.

Short-Finned Pilot Whale, Northern Gulf of Mexico Stock
The short-finned pilot whale is distributed worldwide in tropical to warm waters (Leatherwood and Reeves 1983). Sightings of these animals in the northern Gulf of Mexico occur primarily along the continental shelf and continental slope (Mullin et al. 1991; Southeast Fisheries Science Center, SEFSC, unpublished data). Short-finned pilot whales were seen in all seasons during recent seasonal GulfCet aerial surveys of the northern Gulf of Mexico during 1993-1995 (Davis et al., in preparation). An average abundance estimate for all surveys combined is 353(CV = 0.89) ( Hansen et al. 1995). This species is not listed under the Endangered Species Act.

(5) The type of incidental taking authorization that is being requested (i.e., takes by harassment only; takes by harassment, injury and/or death) and the method of incidental taking;

The intent is to conduct the study so that it should result in no taking of marine mammals. If there is, it would be incidental takes by harassment only.

(6) By age, sex, and reproductive condition (if possible), the number of marine mammals (by species) that may be taken by each type of taking identified in paragraph (a)(5) of this section, and the number of times such takings by each type of taking are likely to occur;

We anticipate "no take" of any species of marine mammals.

(7) The anticipated impact of the activity upon the species or stock;

Depending upon ambient conditions and the sensitivity of the receptor, underwater sounds produced by acoustic operations may be detectable a substantial distance from the activity. Any sound that is detectable is (at least in theory) capable of eliciting a disturbance reaction by a marine mammal or of masking a signal of comparable frequency. An incidental harassment take is presumed to occur when mammals in the vicinity of the acoustic source (or vessel) react to the generated sounds or visual cues.

When the received levels of noise exceed some behavioral reaction threshold, cetaceans will show disturbance reactions (Richardson et al., 1995). The levels, frequencies, and types of noise that will elicit a response vary between and within species, individuals, locations, and seasons. We anticipate little or no behavioral disturbance and no lasting effects on marine mammals from our proposed activities.

Hearing damage is not expected to occur as a result of this project. While it is not known whether a marine mammal very close to a sound source of modest power would be at risk, a temporary threshold shift (TTS) is a theoretical possibility (Richardson et al., 1995).

(8) The anticipated impact of the activity on the availability of the species or stocks of marine mammals for subsistence uses;
No impact anticipated.

(9) The anticipated impact of the activity upon the habitat of the marine mammal populations, and the likelihood of restoration of the affected habitat;
No impact anticipated.

(10) The anticipated impact of the loss or modification of the habitat on the marine mammal populations involved;

No impact anticipated.

(11) The availability and feasibility (economic and technological) of equipment, methods, and manner of conducting such activity or other means of effecting the least practicable adverse impact upon the affected species or stocks, their habitat, and on their availability for subsistence uses, paying particular attention to rookeries, mating grounds, and areas of similar significance;

(1) The smallest possible sources have been selected to minimize the chances of incidental harassment.

(2) To avoid potential incidental harassment of, or injury to, marine mammals, safety zones, (zone of impact), will be established and monitored during daylight hours. Whenever the distance between the seismic source(s) and a marine mammal becomes closer than the assigned safe distance, the USGS will shut down the seismic source.

(3) A zone of impact for the GI or water gun will be set at 30 meters and 20 meters for the Huntec™ boomer system, the Edgetech 512I and the Data Sonics SIS 1000.

(4) For mysticetes and odontocetes operations will cease when these mammals approach a zone of impact of 30 meters for the GI or water gun and 20 meters for the Huntec™, Edgtech 512I sub-bottom profiler and SIS-1000 sidescan system.

(5) For pinnipeds (seals and sealions): if the research vessel approaches a pinniped, a safety radius of 20 m around the boomer, or sidescan fish and 30 m around the air gun will be maintained from the animal(s). However, if a pinniped approaches the seismic source, the USGS will not be required to shut it down. Experience indicates that pinnipeds will come from great distances to scrutinize seismic-reflection operations. Seals have been observed swimming within air gun bubbles, 10 m (33 ft) away from active arrays. More recently, Canadian scientists, who were using a high-frequency seismic system that produced sound closer to pinniped hearing than will the USGS sources, describe how seals frequently approached close to the seismic source, presumably out of curiosity. Therefore, because pinnipeds indicate no adverse reaction to seismic noise, the above-mentioned mitigation plan is proposed. In addition, the USGS will gather information on how often pinnipeds approach the sound source(s) on their own volition, and what effect the source(s) appears to have on them.

(6) During seismic-reflection survey operations, the ship's speed will be 4 to 5 knots so that when the seismic sources are being discharged, nearby marine mammals will have gradual warning of the ship's approach and can move away.

(7) The USGS will have trained marine mammal observers onboard who will have the authority to stop seismic operations whenever mammals enter the zone of impact.

(12) Where the proposed activity would take place in or near a traditional Arctic subsistence hunting area and/or may affect the availability of a species or stock of marine mammal for Arctic subsistence uses, the applicant must submit either a plan of cooperation or information that identifies what measures have been taken and/or will be taken to minimize any adverse effects on the availability of marine mammals for subsistence uses.

We will not be operating in or near Artic waters.

(13) The suggested means of accomplishing the necessary monitoring and reporting that will result in increased knowledge of the species, the level of taking or impacts on populations of marine mammals that are expected to be present while conducting activities and suggested means of minimizing burdens by coordinating such reporting requirements with other schemes already applicable to persons conducting such activity. Monitoring plans should include a description of the survey techniques that would be used to determine the movement and activity of marine mammals near the activity site(s) including migration and other habitat uses, such as feeding. Guidelines for developing a site-specific monitoring plan may be obtained by writing to the Director, Office of Protected Resources; and

Trained marine mammal observers will be employed to monitor the zone of impact during daylight hours. Observers will call for system shut downs when/if marine mammals enter the zone of impact. Observers will monitor work areas for 30 minutes prior to the start up of seismic systems to ensure that no mammals are in the area. New surveys will not be started during night time hours when visibility is poor and the zone of impact cannot be observed for 30 minutes prior to start up. Because of the short zones of impact one trained observer will be on watch at all times during daylight hours.

Data to be recorded during seismic-reflection operations include what the weather conditions are like, such as Beaufort Sea state, wind speed, cloud cover, swell height, precipitation and visibility. For each mammal sighting the observer will record the time, bearing and reticule readings, species, group size, and the animal's surface behavior and orientation.

Observers will instruct geologists to shut down all active seismic sources whenever a marine mammal enters a safety zone.

(14) Suggested means of learning of, encouraging, and coordinating research opportunities, plans, and activities relating to reducing such incidental taking and evaluating its effects.

The USGS is collaborating with the ChevronTexaco Joint Industry Proposal for Gulf of Mexico Gas Hydrate Drilling in order to eliminate or reduce their need to conduct a similar seismic- reflection survey in the same work area.

References

Waring, G.T., J.M. Quintal, S.L. Swartz, Editors 2001. U.S. Atlantic and Gulf of Mexico Marine Mammal Stock Assessments - 2001. . National Marine Fisheries Service Report accessed from www.nmfs.noaa.gov/prot_res/PR2/Stock_Assessment_Program/sars.html.

Waring, G.T., J.M. Quintal, C.P. Fairfield, Editors 2002. Draft U.S. Atlantic and Gulf of Mexico Marine Mammal Stock Assessment - 2002. . National Marine Fisheries Service Report accessed from www.nmfs.noaa.gov/prot_res/PR2/Stock_Assessment_Program/sars.html.

Richardson, W. J., C.R. Greene Jr., C.I. Malme and D.H. Thomson. 1995. Marine Mammals and Noise. Academic Press. San Diego, CA. 576 p.

Hutchinson, D.R., and Detrick, R.S., 1984, Water gun vs Air gun: a comparison: Marine Geophysical Researches, v. 6,p. 295-310.

Caldwell and Caldwell (1989)
Davis et al (1998)
Hansen et al (1995)
Mullin et al (1991)
Schmidly (1981)
Leatherwood and Reeves (1983)
Jefferson et al (1992)
Heyning (1989)
Davis et al (in preparation)
Blaylock and Hoggard (1994)
Perrin et al (1987, 1994)
Perrin and Hohn, (1994)
Perrin and Gilpatrick (no date)
Miyazaki and Perrin (1994)
Perrin and Mead (1994)
Mullin et al (1994)
Perryman et al (1994)

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