Sonar used by the military to spot enemy submarines is to blame for the increasing number of whales stranding themselves on beaches and dying, the scientific committee of the International Whaling Commission said in a report Thursday.
The IWC report adds weight to theories that sonar harms the giant sea mammals, a hypothesis that has been disputed by the military and by the oil and gas industry, which uses the technology to search for energy reserves.
"There is now compelling evidence implicating military sonar as a direct impact on beaked whales in particular," said the report released at the IWC's four-day annual convention.
The report cited examples of bizarre and self-destructive whale behavior that seemed to have been caused by military sonar, such as a mass stampede of 200 melon-headed whales into shallow water in Hawaii earlier this month during a U.S.-Japanese naval training exercise. One animal died.
One theory of scientists is that the noise disrupts whales' communication and navigation systems. Another is that the signals confuse whales in deep water, forcing them to surface quickly, causing rapid decompression and a form of the bends.
The report may strengthen the hand of conservation groups that are threatening to sue the U.S. Navy over its use of mid-frequency sonar. The Natural Resources Defense Council has already secured an injunction limiting the U.S. Navy's use of new low-frequency sonar that can travel vast distances through the oceans and is now targeting the more common mid-frequency sonar.