Researchers Probe Whether Sonar Caused Deaths of Whales

At least a dozen beaked whales--including eight that died--beached themselves in the Canary Islands off the coast of West Africa on Tuesday following a NATO exercise that involved a cluster of warships and submarines.

Authorities are investigating whether powerful sonar caused the deaths, and the government of the islands, a part of Spain, has asked NATO to suspend all military maneuvers in the area, including those by warships.

Earlier this year, an extensive study by the U.S. National Marine Fisheries Service determined that sonar was to blame for the mass stranding of whales during U.S. Navy exercises off the Bahamas in 2000. The study indicated that the Navy’s mid-frequency sonar system caused inner-ear bleeding, disorientation and other injuries that drove the whales to beach themselves.

NATO officials could not be reached for comment Wednesday. At the Pentagon, a spokeswoman for the Navy said officials could not immediately determine if U.S. warships were part of the multinational NATO exercise.

On the islands, veterinary school faculty members and whale researchers began performing necropsies on seven whales Tuesday to help determine the cause of death.

The necropsy of an eighth whale, which washed ashore Wednesday, was underway late Wednesday night, said Teri Rowles, coordinator of marine mammal stranding response for the U.S. fisheries service.

Four whales washed ashore alive and were pushed back to sea in the hope they would survive, Rowles said. Because those animals were not tagged, she said, there is no way to know if the animal that washed ashore Wednesday was one of those pushed back out to sea.

“We know that it was both males and females,” Rowles said, “and most of the animals are juveniles.”

Rowles and other U.S. marine mammal experts have been advising Canary Island officials on what type of tissues to preserve to determine the probable cause of death.

Rowles said at least seven whale heads were removed and taken by refrigerated truck to be preserved at a veterinary school on Grand Canary Island.

“It will probably be several weeks before we know the extent of injury and the potential causes of death,” Rowles said.

Canary Island officials appeared to have acted promptly and correctly in collecting and preserving tissue needed to determine if sonar, explosive blasts or disease were responsible for the deaths, she said. The tissue samples should contain the clues researchers need, she added.

The fisheries service has developed expertise in this area as a result of its 18-month investigation of the mass stranding in the Bahamas in March 2000.

In that case, a quick-thinking researcher collected the heads of dead whales.

Analysis of the tissues showed that bursts of loud sound had torn apart delicate areas around the brain and ears, causing them to hemorrhage.

Some whale researchers believe that sonar was linked to the mass die-offs of whales off the coast of Greece after a NATO exercise using both low-frequency and mid-frequency sonar in 1996. But, unlike in the Bahamas, no tissue samples were collected for researchers.

This week’s stranding included three types of whales: the Cuvier’s beaked whale, Blainville’s beaked whale and Gervais’ beaked whale. These whales are smaller than the great baleen whales, ranging in size from 15 to 23 feet and weighing 2 to 3 tons.