Marine Mammals and Low Frequency Active Sonar (LFAS)

Low Frequency Active Sonar (LFAS) is a military sonar technology designed to detect and track quiet submarines. The U.S. Navy is planning to deploy LFAS in 80% of the world’s oceans at an effective source level of 240 dB. Using the Navy’s number of 61.5 dB (to express the conversion between air and water) 240 dB is equivalent in air to being 20 feet away from a Saturn V rocket at takeoff. NATO and other navies also have LFAS and other high intensity sonars.

Major concerns about LFAS and Marine Mammals include:

  • Evidence suggests that ocean noise pollution may already be affecting hearing in marine mammals. At a workshop on human-produced noise in the marine environment, sponsored by the Office of Naval Research in 1998, Dr. Darlene Ketten stated that about 30% of marine mammal carcasses being collected from beaches show signs of various types of hearing damage, suggesting that many animals may be suffering from hearing loss or that hearing loss may be playing a significant role in these strandings (ONR Workshop on the Effects of Anthropogenic Noise in the Marine Environment, Feb 1998, p70).
  • Scientists and the Marine Mammal Commission have expressed concern that if the LFA system is deployed worldwide as proposed, “all species and populations of marine mammals could possibly be affected” with effects ranging from “death from lung hemorrhage to disruption of feeding, breeding, nursing, acoustic communication, and other vital behavior….” (US Marine Mammal Commission Report to Congress, 1996).
  • In their Environmental Impact Statement (EIS) the US Navy claims that LFAS is safe for marine mammals up to exposure levels of 180 dB. However, no tests on the effects of LFAS on whales have been conducted at exposure levels above 155 dB.
  • The Navy acknowledges that “the lack of empirical data in the received level range of 155 – 180 dB is an issue.” (Appendix D, Final Environmental Impact Statement)
  • Every recorded mass stranding of beaked whales mixed with other species has occurred while naval maneuvers were being conducted nearby.
  • Two of these mass strandings, one in the Mediterranean and one in the Bahamas, have been studied extensively. Official reports on both strandings indicate the whales were exposed to about 150 dB of low to mid-frequency sonar. These strandings demonstrate that 180 dB is not a safe exposure level. (SACLANTCEN Bioacoustics Panel Report; Navy/NOAA Report)
  • Necropsies revealed the whales in the Bahamas had hemorrhaging associated with acoustic trauma in their inner ears and some cranial spaces.

(See Navy/NOAA Report

  • According to the US Navy’s sound charts, LFAS could still approach 160 dB hundreds of miles from the source vessel (Final Environmental Impact Statement, Technical Report 2, Appendix B). In their EIS the Navy estimates that half the marine mammals exposed to 165 dB may experience significant disruption of a biologically significant activity.
  • We know nothing about the long term impacts of LFAS on marine life or effects on ecological processes. The National Research Council has expressed concern that LFAS could affect the marine mammal food chain including fish and zooplankton (Marine Mammals and Low Frequency Sound: Progress since 1994, National Academy Press).
  • Very little is known about how loud sounds cause physiological harm to marine mammals. Scientific debate currently centers on bodily resonance effects and acoustically activated bubble growth. The Navy does not address either of these mechanisms in their EIS.
  • The Navy has advanced passive sonars and listening systems that can safely detect quiet submarines. Passive systems do not reveal the position of the “listener” to the enemy as active sonar does. These safe alternatives have not been adequately addressed in the Navy’s EIS.
  • There are no data on the long term, cumulative and synergistic effects of NATO and other navies deploying LFAS and other high intensity sonars.
  • The Navy has not given sufficient protection to US National Marine Sanctuaries or to the Marine Protected Areas of other nations.
  • Due to the lack of empirical data, deployment of LFAS and other high intensity sonars at this time contradicts the Precautionary Principle and may violate various US environmental laws and international laws and conventions.

Prepared by Marsha L. Green, PhD Ocean Mammal Institute

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