NOAA 2007-R122
Contact: Connie Barclay
NOAA News Releases 2007
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NOAA's National Marine Fisheries Service today proposed a five-year extension of rules protecting marine mammals when the United States Navy operates a certain long-range sonar array. The rules require the U.S. Navy to implement protection measures during operation of its Surveillance Towed Array Sensor System Low Frequency Active Sonar, or SURTASS LFA sonar. The current authorization expires on August 16, 2007.

Based on research and stringent monitoring, NOAA Fisheries Service has determined that marine mammals are unlikely to be injured by the sonar activities under normal operating conditions, and that operation of the LFA sonar will have a negligible impact on affected marine mammal species and stocks overall. The safety measures are designed to prevent injury to marine mammals, including establishing several protected areas and sonar shutdown criteria.

The U.S. Navy's LFA sonar uses a low frequency (about 450 Hz) underwater sound source to locate submarines at long ranges. The LFA sonar operates at a much lower frequency than the standard tactical sonar (approximately 3500 Hz) currently used by the Navy.

According to the U.S. Navy, the SURTASS LFA sonar system meets their need for detection and tracking of new-generation submarines at a longer range. It maximizes the opportunity for U.S. armed forces to safely react to, and defend against potential submarine threats, while remaining a safe distance beyond a submarine's effective weapons range.

Protection measures include:

  • The U.S. Navy will conduct visual monitoring, and both passive and active sonar monitoring, to ensure that marine mammals are detected before they enter the area where LFA sonar levels could cause injury.
  • The U.S. Navy will shutdown the LFA sonar whenever marine mammals or sea turtles are detected within approximately 2 km (1.1 nautical miles or 6,562 ft) from the sound source. Detection in that area is expected to be almost 100 percent effective. It has been determined that at 1 km, the LFA sonar will diminish to a level that would not cause auditory injury to marine mammals.
  • The U.S. Navy will not operate SURTASS LFA sonar at levels greater than 180 dB within 12 nautical miles of all coastlines, or in designated marine mammal biologically important areas, nor will it operate the sonar at levels greater than 145 dB within known human diving areas.
  • Marine mammals that frequent only coastal, estuarine and polar environments would not be affected, since the system will not be operated in coastal waters or polar seas.
  • The U.S. Navy will continue research to monitor effects of low frequency sounds on marine mammals.

The U.S. Navy requested the authorization from NOAA Fisheries Service because SURTASS LFA sonar has the potential to affect marine mammals. Section 101(a)(5) of the Marine Mammal Protection Act allows the incidental "take" or harassment of marine mammals, provided that certain findings are made.

The authorizations, if issued, will be reviewed on an annual basis. Based on monitoring and reporting records kept by trained Navy personnel, NOAA Fisheries Service will assess impacts on marine mammal populations annually, and renew, modify or suspend the authorizations, as appropriate. NOAA Fisheries Service can also immediately revoke its authorization if it is determined that impacts on marine mammals are more than negligible.

NOAA is dedicated to enhancing economic security and national safety through the prediction and research of weather and climate-related events and information service delivery for transportation, and by providing environmental stewardship of our nation's coastal and marine resources. Through the emerging Global Earth Observation System of Systems (GEOSS), NOAA is working with its federal partners, more than 60 countries and the European Commission to develop a global monitoring network that is as integrated as the planet it observes, predicts and protects.

NOAA Fisheries Service is dedicated to protecting and preserving our nation’s living marine resources and their habitat through scientific research, management and enforcement. NOAA Fisheries Service provides effective stewardship of these resources for the benefit of the nation, supporting coastal communities that depend upon them, and helping to provide safe and healthy seafood to consumers and recreational opportunities for the American public. To learn more about NOAA Fisheries Service, please visit: