Sonar Tests a Likely Link to Whale Deaths

The 15 beaked whales that beached themselves last week on the Canary Islands off northwest Africa during a multinational naval exercise suffered ear and brain trauma that may have been caused by high-intensity sonar, according to a preliminary analysis.

Dr. Michel Andre, a veterinarian leading the investigation, noted Monday that “necropsies showed the presence of unspecific lesions, including in the brain and the hearing system, consistent with acoustic impact.”

If a final analysis confirms these findings, it would be the second time that scientists have direct evidence linking mass stranding of whales to bursts of powerful active sonar used by U.S. and other warships.

An exhaustive study of a similar stranding of whales in the Bahamas 2 1/2 years ago showed that intense bursts of midfrequency sonar tore apart delicate tissues of whales’ inner ears and brains, leading to hemorrhaging, disorientation and death.

In the Canary Island strandings last Tuesday and Wednesday, nine whales washed ashore dead, two were spotted dead and floating in nearby coastal waters, and six beached whales were pushed back to sea in the hope they would survive. The whales washed ashore on the islands of Fuerteventura and Lanzarote.

All were beaked whales, which look like very large dolphins. The three types of beaked whales that washed up ranged from 15 to 24 feet in length.

The mass stranding took place during maneuvers for “Neo-Tapon 2002,” a multinational exercise hosted by the Spanish navy, which had invited 11 other NATO member countries to participate, according to the Spanish military.

The U.S. Navy sent the Norfolk, Va.-based destroyer Mahan to join the exercise, which included as many as 58 ships, six submarines and 30 aircraft.

The maneuvers were cut short at the request of the Canary Islands government after the dead whales were discovered.

“Spanish defense officials immediately initiated an investigation,” said U.S. Navy Lt. Cmdr. Pauline Storum. “It would be inappropriate to speculate on the cause of the stranding.”

A spokesman for the North Atlantic Treaty Organization declined to comment directly, saying it was a national issue for Spain and the Canary Islands, which are a part of the nation.

As for the Spanish military, so far it has reported no connection between the maneuvers and the dead whales. In addition, neither U.S., NATO nor Spanish military officials have detailed what kind of sonar systems were deployed during the exercise.

The nine whales that washed ashore dead underwent necropsies on the beach. Two of the whales were too badly decomposed for tissues to be preserved for analysis and a third suffered extensively from parasites, said Vidal Martin of the Society for the Study of Cetaceans in the Canary Archipelago.

The heads of six whales were removed and taken to the veterinary school at Gran Canaria’s University of Las Palmas. Preserving the head is a prerequisite for laboratory analysis of the type of injuries that can be caused by sonar, authorities said.

The preliminary analysis showed hemorrhaging around the brain and thin-walled soft tissue in the head, Martin reported Monday. “At the moment, this veterinarian unit is studying the auditory system,” he said.

The stomachs of seven of the beaked whales contained fresh squid and crustaceans, suggesting that the animals had recently been feeding before they beached themselves, Martin said.

Martin and other researchers have reported similar mass strandings immediately after naval exercises in 1985, 1988, 1989 and 1991. Another mass die-off was reported in Greece after a 1996 NATO exercise involving active midfrequency and low-frequency sonar.

But researchers were unable to retrieve fresh tissues to determine the cause of the deaths.

Active sonar systems, unlike passive listening devices, emit loud bursts of sound that detect the presence of an enemy by the echo that bounces back.