Report: Sonar Causes Deafness in Dolphins
What many people had already assumed has now been proven true. Sonar has the ability to temporarily deafen dolphins.
A new study, courtesy of Aran Mooney and others from the Hawaii Institute of Marine Biology, confirms that continuous sonar "pings" cause temporary hearing loss in dolphins (and most likely other cetaceans). Mooney and his team did find, however, that the dolphins would have to be close to the source of the sonar for such severe effects to occur. These sorts of circumstances, they contend, are unlikely since dolphins would almost immediately swim away when confronted with such sounds. Despite that qualification, there is significant proof that under certain conditions, sonar can indeed prove lethal to both dolphins and whales.
In 2002, for the first time, the U.S. Navy admitted that sonar could be dangerous to marine mammals after 16 whales became stranded in the Bahamas. Autopsies revealed hemorrhaging near the ears in each of the dead whales. The whales were caught in the Great Bahama canyon, a hot spot for military exercises. The canyon essentially magnified sonar sounds from the surrounding areas, creating a perfect sonar storm, if you will. This was a rare combination of environmental factors, but the whales are, nonetheless, dead.
In 2008, 26 stranded dolphins died off the coast of Cornwall. It was confirmed after the incident that sonar was indeed being used in British military exercises around the time of their deaths.
Unfortunately for environmentalists, and sea-born mammals, the U.S. Supreme Court ruled last year that sonar training exercises off the coast of Southern California could continue uninhibited by measures intended to protect marine life. While we certainly think that our nation's security is important, we think that our nation's environment is, too. We are sure that some kind of a compromise can, and must, be made. [From: NewScientist]