Navy Sonar Operations Proposal - 21/10/2009

NOAA's Fisheries Service is seeking comments now through 19th November on its proposed rule to authorise impacts to marine mammals during Navy training exercises around the Mariana Islands. The NOAA proposal includes protective measures designed to minimise effects on marine mammals.



The Navy has requested an authorization under the Marine Mammal Protection Act, because the mid-frequency sound generated by tactical sonar, and the sound and pressure generated by detonating explosives, may affect the behavior of some marine mammals, or cause a temporary loss of their hearing sensitivity.


NOAA's Fisheries Service does not expect the exercises to result in serious injury or death to marine mammals, and is proposing the Navy use mitigation measures to avoid injury or death. However, exposure to sonar in certain circumstances has been associated with the stranding of some marine mammals, and some injury or death may occur despite the best efforts of the Navy. Therefore, the proposed authorisation allows for a small number of incidental injuries to marine mammals.


Under the authorisation, the Navy would have to follow mitigation measures to minimize effects on marine mammals, including:

  • establishing marine mammal safety zones around each vessel using sonar;
  • using Navy observers to shut down sonar operations if marine mammals are seen within designated safety zones;
  • using exclusion zones to ensure that explosives are not detonated when animals are detected within a certain distance;
  • implementing a stranding response plan that includes a training shutdown provision in certain circumstances, and allows for the Navy to contribute in-kind services to NOAA's Fisheries Service if the agency has to conduct a stranding response and investigation.

These measures should minimise the potential for injury or death, and significantly reduce the number of marine mammals exposed to levels of sound likely to cause temporary loss of hearing.


NOAA's Fisheries Service and the Navy have worked to develop a robust monitoring plan to use independent, experienced vessel-based marine mammal observers (as well as Navy watchstanders), and passive acoustic monitoring to help better understand how marine mammals respond to various levels of sound and to assess the effectiveness of mitigation measures. Additionally, the Navy is developing (with input from NOAA's Fisheries Service) an Integrated comprehensive monitoring plan to better prioritise monitoring goals and standardise data collection methods across all of their U.S. range complexes.


NOAA's Fisheries Service will accept comments on the application and proposed authorisation through 19th November. Comments should be addressed to: Michael Payne, Chief of the Permits, Conservation, and Education Division. Office of Protected Resources, NMFS. 1315 East West Highway. Silver Spring, MD 20910 USA. Electronic public comments may be submitted via the Federal eRulemaking Portal using the identifier 0648-AW91.

Last updated: 30/11/2020