2003 CPEO Military List Archive

From: CPEO Moderator <cpeo@cpeo.org>
Date: 8 Oct 2003 23:13:01 -0000
Reply: cpeo-military
Subject: [CPEO-MEF] Navy Sonar Affecting Whales
Navy Sonar Affecting Whales
By Marc Kaufman
Wednesday, October 8, 2003; 6:11 PM

High-powered sonar from Navy ships appears to be giving whales and other marine mammals a version of the bends, causing them to develop dangerous gas bubbles in some vital organs and blood vessels, to beach themselves and die, according to a study published today in the journal Nature.

Reporting on beaked whales that were stranded in the Canary Islands soon after an international naval exercise last year, researchers for the first time found a condition similar to decompression sickness in 10 of 14 dead animals.

The new data begins to explain how and why high decibel mid-frequency sonar used by the U.S. Navy and other military fleets appears to cause some deep-diving marine mammals to die. Although the bends was previously unheard of in whales, dolphins and porpoises, the British and Spanish researchers concluded that a marine mammal version of decompression sickness was "the most likely cause" of the Canary Island strandings.

"This is the best data we've ever seen from a sonar-related stranding," said Roger Gentry, coordinator of the government's National Oceanic and Atmospheric Administration Fisheries Acoustics Team. He said that NOAA will hold a workshop with the authors and others in the field later this year to assess the new information and try to reach some scientific conclusions.

The new research from the Canary Islands suggests two possible ways for the whales to be harmed by the gas bubbles. One is similar to how humans get the bends: that the whales panic at the sound of the loud sonar noises and rise too quickly from deep water. As they rise, nitrogen bubbles can be formed from the rapid change in pressure and cause the bends. The other hypothesis involves bubble formation caused directly by the sonar on gas nuclei, or bubble "precursors," in whale tissues already highly saturated with nitrogen.

Gentry said that the scientific community, at this point, remains skeptical that rapid ascents are causing the bubble-formation. "From an evolutionary point of view, it does not seem likely," he said. "Whales have been diving like this forever, and should have evolved mechanisms so they wouldn't succumb to decompression."

The Canary Island strandings and research involve mid-frequency (or pitch) sonar coming from Spanish-led, international naval maneuver. But they could have impact on a contentious debate now going on over the U.S. Navy's desire to deploy very loud low-frequency sonar around the world to detect "quiet" submarines. That effort was stopped by a federal magistrate in California in August, who said the government had violated several environmental laws in giving the Navy permission to deploy the new sonar globally.

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