Military Sonar kills Whales and Dolphins

international | environment | news report Friday October 17, 2003 09:55 by James McKenna jimmymac61 at hotmail dot com

Gas bubble lesions in cetaceans

In a paper published in Nature magazine, scientists from a British Government-funded research programme show the first evidence of gas bubbles and associated tissue trauma in six dolphins, a porpoise and a beaked whale recovered from British waters.

In September 2002 an investigation conducted by the University of Las Palmas (Gran Canaria) into a mass stranding of beaked whales on the beaches of Fuerteventura and Lanzarote in the Canary Islands found similar evidence of gas bubbles in blood vessels and hemorrhaged vital organs The beaching occurred four hours after military mid-frequency active sonar activities commenced there on September 24, 2002 .
"We think the animals arrived at the coast after the beginning of the exercises in an injured state due to a disseminated microvascular hemorrhage in vital organs, associated with a systemic embolism," said Antonio Fernández, one of the Spanish researchers. "After beaching, their situation was worse due to the well-known stress stranding syndrome that did more severity to the lesions, resulting in cardiovascular collapse and death."
Roger Gentry, a scientist with the National Marine Fisheries Service in Silver Spring, Maryland, who studies marine mammal strandings, said the connection between the beaked whale strandings and the military sonar exercises is clear.
The U.S. Navy and other militaries including the Irish Navy have deployed mid-frequency active sonar. Deployed as part of training to secure militarily strategic locations and coastline active sonar disrups and damages marine life and has increased incidences of marine mammal strandings.
Environmentalists are now actively opposing testing of a new technology, called low-frequency sonar (100 to 300 hertz). This August a U.S. District Court judge in California where whales have also beached during navy exercises ordered the U.S. Navy to negotiate with environmental groups on when, where, and how it tests the low-frequency sonar .
Low-frequency sound waves can rapidly compress and then expand microscopic bubbles of gas in the cetaceans tissue. Each sound wave causes the bubble to absorb more and more of the gas dissolved in the bloodstream, eventually making the bubbles big enough to rupture tissues.