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Taking and Importing Marine Mammals; Taking Marine Mammals Incidental to Conducting Oil and Gas Exploration Activities in the Gulf of Mexico

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


Notice of Intent to prepare an Environmental Impact Statement; notice of public meetings; and request for scoping comments.


NMFS has received a request from the U.S. Minerals Management Service (MMS), U.S. Department of the Interior, for regulations to authorize the take, by harassment, of small numbers of marine mammals incidental to seismic surveys during oil and gas exploration activities by the U.S. oil and Start Printed Page 67536gas industry in the Gulf of Mexico (GOM). By this document, NMFS announces: (1) its intention to prepare an Environmental Impact Statement (EIS); (2) commencement of its scoping process under the National Environmental Policy Act (NEPA); (3) a request for public comment on the scope of the EIS; and (4) times, dates, and locations for public scoping meetings.


Written comments and information must be received no later than December 22, 2004. Two public scoping meetings are scheduled as follows:

1. December 3, 2004, 9 a.m. - approximately 12 noon, New Orleans, LA.

2. December 16, 2004, 9 a.m. - approximately 12 noon, Silver Spring, MD.


The public scoping meetings will be held at the following locations:

1. New Orleans: Location to be determined. This meeting will be held on the day following the Marine Mammal Commission's (MMC) Fourth Plenary Meeting of the Advisory Committee on Acoustic Impacts on Marine Mammals. The scoping meeting location will be provided during the MMC meeting.

2. Silver Spring: Silver Spring Metro Center, NOAA Science Center, 1301 East-West Highway, Silver Spring, MD 20910.

Submit written comments to Steve Leathery, Chief, Permits, Conservation and Education Division, Office of Protected Resources, National Marine Fisheries Service, 1315 East-West Highway, Silver Spring, MD 20910-3226. The mailbox address for providing e-mail comments is E-mail comments sent to other addresses may not be timely received for consideration. Comments sent via e-mail, including all attachments, must not exceed a 10-megabyte file size.

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Kenneth R. Hollingshead, NMFS, 301-713-2289, ext 128.

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Section 101(a)(5)(A) of the Marine Mammal Protection Act (16 U.S.C. 1361 et seq.)(MMPA) directs the Secretary of Commerce (Secretary) 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 regulations are issued.

Permission may be granted for periods of 5 years or less if the Secretary 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 regulations are prescribed setting forth the permissible methods of taking, other means of effecting the least practicable adverse impact on the species or stocks, and requirements pertaining to the monitoring and reporting of such taking.

On December 20, 2002, MMS petitioned NMFS for rulemaking under section 101(a)(5)(A) of the MMPA to authorize any potential “take,” by “harassment,” of sperm whales (Physeter macrocephalus) incidental to conducting seismic surveys during oil and gas exploration activities in the GOM. “Take” means to harass, hunt, capture, or kill, or attempt to harass, hunt, capture, or kill. Except for certain activities not pertinent here, “harassment” means

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].

NMFS published a notice of receipt of the MMS application on March 3, 2003 (68 FR 9991). MMS submitted a revised petition to include the incidental take of other species of marine mammals, such as the Bryde's whale, several species of dolphins and beaked whales on September 26, 2004. On July 30, 2004, MMS completed its Final Programmatic Environmental Assessment (Final PEA) on this action and made that document available to the public at​homepg/​regulate/​environ/​nepa/​2004-054.pdf

Notice of Intent

The comment period on the NMFS' notice of receipt of the MMS application was extended until April 16, 2003 (see 68 FR 16262, April 3, 2003). During the public comment period, NMFS received comments recommending preparation of a Draft EIS under NEPA on this action. NMFS has considered this request and determined that it will prepare an EIS for its proposed rulemaking governing authorizations to take marine mammals incidental to oil and gas seismic surveys in the GOM. This decision is based on a combination of factors: (1) public concern over impacts of oil and gas exploration activities on the marine environment, which includes marine mammals; (2) proposed use of computer modeling as one of two methods for calculating incidental take levels for marine mammals and sea turtles for a geographic area where multiple seismic sources may be operating simultaneously; (3) incorporation of a scientifically-based risk assessment for marine mammals; (4) possible use of energy criteria rather than the current pressure criteria to calculate marine mammal take levels, especially to calculate potential multiple exposures; and (5) incorporation of new acoustic guidelines for assessing impacts of sound on marine mammals.

Description of the Specified Activity

Marine geophysical seismic surveys are conducted to obtain information on surface and near-surface geology (high-resolution surveys) and on subsurface structures and formations (seismic surveys and vertical seismic profile (VSP) surveys).

Typical seismic surveying operations tow an array of airguns (the seismic sound source) and a streamer (signal receiver cable) behind the vessel, 5-10 m (16.4-32.8 ft) below the sea surface. The airgun array produces a burst of underwater sound by releasing compressed air into the water column that creates an acoustic energy pulse. The release of compressed air every several seconds creates a regular series of strong acoustic impulses separated by silent periods lasting 7-16 seconds, depending on survey type and depth to the target formations. Airgun arrays are designed to focus the sound energy downward. Acoustic signals are reflected off the subsurface sedimentary layers and recorded near the water surface by hydrophones spaced within the streamer cables. Some surveys employ ocean-bottom seismometers as the receiving instrument. Vessel speed is typically 4.5-6 knots (about 4-8 mph) with gear deployed.

Three-Dimensional (3-D) seismic surveying enables a more accurate assessment of potential hydrocarbon reservoirs to optimally locate exploration and development wells, and minimize the number of wells required to develop a field. State-of-the-art interactive computer mapping systems can handle much denser data coverage than older 2-D seismic surveys. Multiple-source and multiple-streamer technologies are used for 3-D seismic surveys. A typical 3-D survey might employ a dual array of 18 guns per array. Each array might emit a 3,000 cubic-inch burst of compressed air at 2,000 kilojoule (kJ) of acoustic energy for each burst. The hydrophone Start Printed Page 67537streamer array might consist of 6-8 parallel cables, each 6-8 km (3.7-5 mi) long, spaced 75 m (246 ft) apart. A series of 3-D surveys collected over time (4-D seismic survey) is used for reservoir monitoring and management (the movement of oil, gas, and water in the reservoirs can be observed over time). Seismic surveys may span one day, weeks, or months. MMS has requested an authorization under the MMPA for the incidental harassment (Level A and Level B) of marine mammals during 2-D and 3-D seismic surveys, high-resolution surveys, and VSP surveys.

For management purposes MMS has divided the Northern GOM into three planning areas: Eastern, Central and Western. In general, Federal waters offshore Florida and Alabama are in the Eastern Planning Area, Federal waters offshore Mississippi and Louisiana are in the Central Planning Area, and Federal waters offshore Texas are in the Western Planning Area. For seismic exploration, about 1300 blocks in the Western and Central Planning Areas have not yet been surveyed with 3-D seismic techniques (R. Brinkman, MMS GOM Region, pers comm, 2004). It is assumed that a lower level of new seismic survey activity will occur in the Eastern Planning Area relative to the other two areas (i.e. the vast majority of survey activities are expected in the Central and Western Planning Areas). Industry interest in the Eastern GOM has historically been limited to the westernmost portions of the planning area and is usually defined by MMS' 5-Year Leasing Plan (MMS, 2002).

The Federal waters of the GOM are inhabited by a diverse assemblage of marine mammal species. When seismic surveys are conducted acoustic energy is introduced into Gulf waters that may adversely impact marine mammals in the vicinity of the activity. The potential adverse impacts to marine mammals are detailed in MMS' 2004 Final PEA. In general, loud underwater noise has the potential to harass, injure, and possibly cause the mortality of marine mammals. While the serious injury or mortality of marine mammals is believed to be unlikely, especially due to the implementation of mitigation measures to protect marine mammals (see Mitigation), NMFS' Draft EIS will investigate and discuss the potential for injury and mortality.

MMS is seeking regulations under the MMPA governing the possible harassment and non-serious injury of several species of marine mammals in the GOM as a result of seismic surveys as described in MMS (2004). The MMPA regulations are requested by MMS on the behalf of the offshore oil and gas industry and seismic contractors operating within the GOM. NMFS expects that seismic vessel owners will obtain Letters of Authorization, in accordance with 50 CFR 216.106, to incidentally take marine mammals under the requested regulations.

Potential Effects of Seismic Activities on Marine Mammals

The effects of sounds from airgun arrays might include one or more of the following: tolerance, masking of natural sounds, behavioral disturbance and perhaps temporary or permanent hearing impairment (Richardson et al. 1995). In addition, intense acoustic events may cause trauma to tissues associated with organs vital for hearing, sound production, respiration and other functions.

Using sperm whales as an example, this species spends large amounts of time at depth and uses low frequency sound to communicate and navigate. Therefore, sperm whales are considered to be sensitive to the marine acoustic environment and may respond to sound emissions in many ways. Reactions to acoustic emissions may include, but are not limited to, cessation of vocalizations, disruption of feeding and dive behaviors, physical avoidance of noisy areas and temporary or permanent hearing impairment if the noise is strong enough and/or if the animal is in close proximity to the sound source. Such impairment could have the potential to diminish the individual's chance for survival or potential for reproduction. Tolerance of noise is often demonstrated, but this does not necessarily mean that the animals are unaffected by noise. Also, adverse levels of noise might interrupt or decrease feeding activity, social interactions, or parenting. Responses to seismic activity causing adverse effects to individuals and cow/calf pairs, reproduction, feeding, or causing temporary or permanent threshold shifts in hearing may negatively impact GOM marine mammal stocks if the disruptions are extended. There are no documented data on auditory-induced physical effects of underwater seismic noise on sperm whales or other marine mammals. There is observational evidence that sperm whales may be temporarily displaced away from areas where seismic operations are underway. MMS believes that sperm whales are not being significantly displaced from the northern GOM due to seismic surveys. NMFS notes, however, that no data have been provided to support this statement. At this time it is unknown whether sperm whale site fidelity in the GOM reflects low sensitivity to seismic noise or a high motivation to remain in the area in spite of this noise. Details of seismic noise and its potential impact on marine mammals have been described in MMS (2004) and will be addressed in the NMFS Draft EIS.

In the absence of species-specific data on auditory impacts for marine mammals, a received sound pressure level of 180 dB re 1 μPa (rms) or greater has been used by NMFS as a threshold for concern about temporary and/or permanent hearing impairment (Level A Harassment). This criterion, which will be included in the Draft EIS analysis, was developed as a result of public workshops held in 1998 (HESS, 1999) and 1999 (NMFS, 1999). However, this criterion does not consider the frequency component, nature of the sound source, the hearing sensitivities of different cetacean species and other relevant factors. NMFS expects that the Draft EIS will employ the latest scientific information to estimate Level A Harassment impacts on marine mammals in the GOM.

A spreading loss equation of 20 log R is recommended by Richardson et al. (1995) for calculating underwater transmission loss in deep water. NMFS believes a spreading loss equation of 15 log R or less may be more appropriate for shallow water areas of the GOM where the horizontal propagation range reaches approximately 1.0 times the water depth. Using a spreading equation of 15 log(R), the 180-dB re 1 μPa (rms) isopleth in surface and near-surface waters occurs at approximately 295 m (968 ft) from a standard airgun array (4550 in3, 240 dB re 1 μPa 0-pk; 230 dB re 1 μPa rms). Similarly, the 180 dB re 1 μPa (rms) isopleth vertically below the seismic source is calculated to be 6.3 km (3.4 nm). By means of a Gulf-wide Notice to Lessees (NTL) for all seismic activities (30 CFR 250.103), MMS has implemented a horizontal 500-m (1640-ft) radius impact (seismic shut-down) zone to minimize possible effects to sperm whales. The NTL was updated in 2004 (NTL No. 2004-G01) to include all whales (but not dolphins) under this 500-m (1640-ft) impact (seismic shut-down) zone. This NTL can be viewed at the following location:​homepg/​regulate/​regs/​ntls/​ntl04-g01.html

For larger 2-D and 3-D towed arrays with estimated source levels of 257 dB re 1 μPa rms, a 500-m (1640-ft) impact zone equates to an estimated received level of approximately 232 dB. According to NMFS (2002a), at source levels of 257 dB (rms), the 20 log(R) model and associated calculation above produce received levels of 203 dB re 1 Start Printed Page 67538μPa at 500 m (1640 ft) from the source in subsurface waters (a conservative estimate) and 183 dB in surface waters due to the array effect. Presently, the impact zone of 500 m (1640 ft) closely approximates the received dB levels in surface waters, but may not accurately reflect the 180-dB isopleth and associated impact zone beneath an array. Recently, Tolstoy et al. (2004) measured the propagation for a 3705 in3 airgun array (twelve 2000-psi Bolt airguns of 80-850 in3 with 0-pk = 31 bar-m (250 dB re 1 μPa.m)). The 180 dB isopleth in shallow surface waters was at approximately 2000 m (6562 ft).

In the absence of scientific, species-specific information for marine mammals in the GOM, a received sound pressure level of 160 dB re 1 μPa (rms) has been used by NMFS as the threshold indicator of potential concern about disturbance of marine mammals in the wild through disruption of behavioral patterns, including but not limited to, migration, breathing, nursing, breeding, feeding, or sheltering (Level B Harassment). Using spherical spreading (15 log(R)), subtracting 20 dB for the array effect, and 10 dB for zero-to-peak to RMS conversion, the 160 dB re 1 μPa (rms) isopleth in surface and near-surface waters occurs at about 6.3 km (3.4 nm) from the seismic airgun source. Similarly, the 160 dB re 1 μPa (rms) isopleth below the seismic source is calculated to extend to the sea floor. MMS (2004) calculates the 160-dB isopleth level at 3000 m (1.6 nm) based on the 20 log R model for a 4550 in3 array (230 dB re 1 μPa (rms) source level) and Tolstoy et al. (2004) measured the propagation for a 3705 in3 airgun array to the 160 dB rms isopleth in GOM surface waters at 9 km (4.8 nm) in shallow water and 2.5 km (1.3 nm) in deep water.

These discrepancies between dB calculations and measurements for deep and shallow water and for surface and sub-surface waters indicate a need for better data to effectively formulate models that can be used to calculate impact zones for marine mammals. Therefore, NMFS plans to include in its Draft EIS empirical information on airgun array sizes used in the GOM and actual propagation measurements made in the GOM. NMFS believes this information is vital in order to estimate impacts on marine mammals and sea turtles and for appropriate impact assessment modeling.


The environmental review of the MMS MMPA application will be conducted in accordance with the requirements of NEPA, NEPA regulations (40 CFR 1500-1508) and other appropriate Federal laws and regulations, and the NMFS policies and procedures for compliance with those regulations (NOAA Administrative Order 216-6 -Environmental Review Procedures for Implementing the National Environmental Policy Act, May 20, 1999).

A preliminary list of the primary issues that NMFS will discuss in the EIS is provided here. Additional issues may be identified at the public scoping meetings and in written comments.

  • marine mammals-effects of seismic noise on all species;
  • other biological resources- effects of seismic noise on sea turtles, fish, coastal and marine birds, benthic communities, plankton;
  • commercial and recreational fisheries;
  • cumulative effects on marine mammals from military activities and commercial shipping in the GOM.

EIS Alternatives

NMFS will explore and evaluate a full range of reasonable alternatives in the EIS, including the proposed action and the no-action alternative. The proposed action will be to authorize, through rulemaking and subsequent Letters of Authorization, the incidental taking of marine mammals by oil and gas seismic vessels conducting seismic surveys in state and Federal waters of the GOM. The proposed action will also include mitigation measures such as biological observers on all seismic vessels in all operating areas, gradual ramp-up of the airgun arrays, monitoring established safety zones, and power-down/shut-down procedures to protect marine mammals that are in or approaching the established safety zone.

Alternatives in the EIS will address a suite of other mitigation and monitoring measures, including: (1) requiring biological observers only on seismic vessels operating in waters deeper than 200 m (656 ft); (2) requiring a vessel-based passive acoustic monitoring (PAM) system with trained biological technicians or biologists; (3) use of PAM only in water depths greater than 200 m (656 ft), principally on the continental slope offshore of the Mississippi River mouth and extending east to the DeSoto Canyon area in the Eastern Planning Area; (4) use of vessel-based passive and active acoustic monitoring; (5) use of PAM and active acoustic monitoring only in water depths greater than 200 m (656 ft) principally in continental slope offshore of the Mississippi River mouth and extending east to the DeSoto Canyon area in the Eastern Planning Area; (6) time/area closures to protect marine mammals; and (7) use of aircraft or support vessels for marine mammal monitoring.

Identified EIS Mitigation Measures

In response to NMFS questions regarding the availability and feasibility (economic and technological) of equipment, methods and manner of conducting oil and gas seismic surveys to effect the least practicable adverse impact on potentially affected marine mammals, MMS responded that current mitigation measures for the oil and gas seismic industry in the GOM include: ramp-up, visual monitoring, establishment of an impact zone (currently 500 m (1,640-ft) around the sound source), and mandatory “shut-down” to avoid injury to marine mammals in or about to enter the impact zone. Ramp-up, or soft start, requires seismic operators to start firing the acoustic array with one gun and gradually over time add more guns until the array is fully operational. Theoretically, this allows whales in the area that can hear the low-frequency sounds from the array to move away from the sound source before discomfort or injury might result. Visual observers monitor the area around the sound source for 30 minutes prior to ramp-up and throughout seismic operations. Any time a marine mammal enters or surfaces within 500 m (1,640 ft) of the sound source, seismic operations immediately cease in order to minimize the exposure of the whales or dolphins to potentially damaging sound levels. In addition to these mitigation measures, the Draft EIS will discuss the use of PAM and active acoustic monitoring, certain time/area closures to protect marine mammals, and the use of aircraft or support vessels for marine mammal monitoring.

Identified EIS Monitoring Measures

Currently, monitoring and reporting requirements for the offshore seismic industry are set forth by MMS in MMS NTL No. 2004-G01. This will be one of the alternatives in the Draft EIS. MMS intends to continue this monitoring program until a revised monitoring program is developed during the NEPA, MMPA and Endangered Species Act reviews.

Visual observers must monitor waters (with the assistance of binoculars) for marine mammals within and adjacent to the exclusion zone for 30 minutes prior to initiating the airgun ramp-up procedures. Observers must monitor the exclusion zone and adjacent waters during seismic operations, unless atmospheric conditions reduce visibility to zero or during hours of darkness (i.e., Start Printed Page 67539night). When marine mammals are observed entering or within the exclusion zone, observers must call for the shut down of the airgun array; seismic operators must shut down the seismic array when instructed by an observer. Ramp-up and seismic activities may be reinitiated only when the observer has: (a) determined that the marine mammal(s) has departed the exclusion zone, and (b) visually monitored the exclusion zone for at least 20 minutes since the mammal sighting within the exclusion zone.


NMFS requests public comments on the range of alternatives and the scope of issues that should be considered in the EIS. NMFS recommends participants review the MMS PEA prior to submitting comments.

At the public scoping meeting a brief presentation may precede a request for public information and comments. Those who intend to submit verbal comments will be asked to submit a speaker card (available at the meeting). Depending on how many cards NMFS receives, speakers may be required to limit their verbal comments to a specified period of time so that all persons wishing to comment may have an equal opportunity to do so. NMFS encourages members of the public who provide verbal comments to also submit them in writing, along with any associated graphics, so as to ensure accuracy. All comments, written or verbal, will become part of the public record on this matter.

The public scoping meetings will be accessible to persons with disabilities. Requests for sign language interpretation or other auxiliary aids should be directed to Ken Hollingshead (see FOR FURTHER INFORMATION CONTACT). Photo identification will be required to attend these meetings.

Information and questions regarding the proposed action and/or scoping may be obtained by writing to the person listed herein (see ADDRESSES), or by telephoning the person listed (see FOR FURTHER INFORMATION CONTACT).

Additional opportunities for public review and comment will be provided when the draft EIS is completed. A notice of availability will be published in the Federal Register. After release of the draft EIS, NMFS intends to hold public meetings in various cities in Florida, Texas, and Louisiana.

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Dated: November 12, 2004.

Laurie K. Allen,

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

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[FR Doc. 04-25643 Filed 11-17-04; 8:45 am]