[CPEO-MEF] Navy Sonar Affecting Whales

[CPEO Moderator <cpeo@cpeo.org>]

THE WASHINGTON POST
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.

This article can be viewed at:
http://www.washingtonpost.com/wp-dyn/articles/A63215-2003Oct8.html

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