New Sonar Poses Threat to Cetaceans

The US Navy is hoping to widen its testing of SURTASS-LFS, a new generation of active sonar expected to out-stride any previous sonar technology. The new sonar operates at lower frequencies than older systems, producing sonar pings that travel further than ever before. SURTASS-LFS may be a technological leap, but it is also a grave threat to marine life.

The US Navy intends to equip four ships with the new sonar system and then deploy those ships around the globe so they can test the sonar in many of the world's oceans. Before this can happen, the US Navy must obtain a permit from the National Marine Fisheries Service, an all-too-simple formality (the permit is quickly being funneled down the path to approval). Conservationists argue that the public received insufficient time to comment on the impending permit approval and that little research has been conducted to evaluate (and limit) the effects the SURTASS-LFS sonar will have on cetaceans.

What is 'Active Sonar'?

Militaries around the globe use active sonar to visualize the underwater world. Active sonar emits loud bursts of sound, or 'pings', that travel through tens or hundreds of miles of ocean. A ping can be as loud as 235 decibels—an auditory blast that rivals the noise produced by a Saturn V rocket launch. These powerful sound waves bounce off of everything in their path and the reflected sound is picked up by sonar receivers that interpret the echoes and use them to create an 'auditory map' of the underwater landscape.

How Does Active Sonar Threaten Cetaceans?

Sound travels with great efficiency through water and moves faster and further than it does in air. Sonar pings can be very loud, which means they carry with them a great deal of energy—energy that can inflict severe internal injuries upon marine animals that happen to be too close to the source of the ping. In addition to internal injuries, sonar can also cause panic and disorientation.

Many cetaceans rely on sound for their survival. Toothed whales, for instance, navigate their way through the ocean's darkness using echolocation. They produce sounds either in their nasal plug or larynx (scientists disagree which organ is used in sound production). The sound bounces off of nearby objects and reflects back to the animal. Special sound-conducting tissue located in the whale's lower jaw directs the sound to its inner ear.

Sonar-Related Strandings

A long list of cetacean injuries and fatal strandings have been attributed to sonar-related activities over recent years. The following are just a few of the incidents that took place when Navy sonar activity was conducted close to the stranding site:

• January 2005 - 34 whales stranded, Outer Banks, North Carolina.
• July 2004 - 4 beaked whales stranded, Canary Islands.
• June 2004 - 200 melon-headed whales congregate in shallow waters, Hanalei Bay, Hawaii.
• May 2003 - 11 harbor porpoises stranded, Haro Straight, Washington State.
• September 2002 - 14 beaked whales stranded, Canary Islands.
• April 2002 - One beaked whale and one humpback whale stranded, near Vieques.

Find out more:

• Protest Raised over New Tests of Naval Sonar (NPR)
• Sounding the Depths: The Rising Toll of Sonar, Shipping and Industrial Ocean Noise on Marine Life (NRDC)
• Protecting Whales from Dangerous Sonar (NRDC)
• New Evidence Shows Marine Life Is Under Seige from Rising Ocean Noise (NRDC)
• Cetacea Echolocation (NOAA)

Photo © Daniel Benhaim / iStockPhoto.