Sonar

Active sonar is the transmission of sound energy for the purpose of sensing the environment by interpreting features of received signals. People have developed sophisticated ways of using sound to probe the marine environment, including:

• High-frequency, bottom-mapping multi-beam sonar systems that provide high-resolution images of bottom features
• Mid-frequency tactical military sonar to detect submarines and other underwater objects
• Low-frequency systems to detect large objects with lower resolution over larger ranges

The extent to which human sonar systems may affect marine life depends critically on the system in question, the environments in which they are operated, and animals exposed to them. In certain conditions, it appears likely--if not certain--that mid-frequency military sonar has played some role in marine mammal stranding events. These further appear to be more likely to involve deep-diving marine mammal species in areas of complex, steep bottom bathymetry. However, there are many more unknowns than information regarding the certainty of these effects, and whether they are necessarily limited to these conditions.

More information

• Behavioral Response Studies/ Controlled Exposure Experiments
  • Beaked whales respond to simulated and actual Navy sonar (Tyack et al. 2011)
• Marine Mammal Health and Stranding Response Program
  • New techniques to diagnose possible noise-related strandings workshop (2006)
• Stranding events associated with military sonar
  • Advisory Committee on Acoustic Impacts on Marine Mammals (MMC 2006)
  • Understanding the impacts of anthropogenic sound on beaked whales (Cox et al. 2006)
  • Bahamas 2000
    • Acoustic Resonance Workshop (2002)
• Navy Marine and Ocean Resources web site
• Navy SURTASS LFA web site

Updated: October 11, 2012