Originally created 03/11/01

Sonar killing whales, scientist charges



BREMERTON, Wash. - Oceans off the Bahamas seem lonelier this winter as whale researchers scan the water for beaked whales they have studied for years, a scientist says.

At least some of the whales were caught in a Navy exercise nearly a year ago, and now Ken Balcomb fears many whales were killed by sonar.

Balcomb, who divides his time between Washington state's San Juan Islands and the Bahamas, has spent years identifying beaked whales. Now, the only ones he sees are strangers - probably visitors from other areas.

Balcomb, of the Center for Whale Research, is normally a reserved and cautious scientist. Recently, he sent a strongly worded letter to the Navy warning that the proposed deployment of a new low-frequency sonar system could have devastating effects on whales throughout the world.

The Navy has acknowledged that sonar may have contributed to the deaths of seven whales in the Bahamas. The whales beached themselves March 15 during an exercise involving five ships.

A natural phenomenon, called a "surface duct," may have transmitted greater volumes of sound to lower depths, according to a report.

The National Marine Fisheries Service suggested that the whales may have become disoriented by the sound and died due to beaching.

Balcomb is calling for better analysis.

"Considering the observed damage to the whales that stranded and died and the short time period between stranding and death, the NMFS statement that the whales died from stranding is patently absurd," Balcomb said in his letter. "The whales that we observed swimming toward shore and stranding were only the temporary survivors of an acoustic holocaust that can be likened to fishing with dynamite."

Balcomb contends that the Navy has not adequately considered how loud noise from sonar may resonate within air chambers located in the whales' skulls.

"The killing is largely due to resonance phenomena in the whales' cranial air spaces that are tearing apart delicate tissues around the brain and ears," Balcomb said in his letter. "This is an entirely separate issue from auditory thresholds and traumas that the Navy has fixated upon."

Balcomb's letter uses mathematical equations to describe the relationship between the size of air spaces and the resulting resonance.

He also questions whether the Navy has proposed adequate precautions with its new low-frequency sonar, which he says can create resonance frequencies.

"The Navy has consistently tried to de-link the low-frequency active sonar with the normal sonar," he said. "If you really investigate resonance, you will see there is a common denominator."

Joe Johnson, who leads a team studying the environmental impacts of low-frequency sonar, said laboratory studies were done to measure resonance effects on rats, mice and guinea pigs.

It takes a fairly steady tone to create resonance, he said. Frequency change and sound levels used in the low-frequency sonar system are not great enough to cause injury in whales, although they may cause behavioral changes.

"Based on everything we've seen," he said, "this is not going to have an impact on the species."

If in doubt, Johnson said, consider that the large whales - blue whales and humpback whales - generate the same volumes and frequencies as the Navy's low-frequency sonar.

Balcomb, a former Navy man himself, said he is disappointed that the Navy has not provided adequate answers to the Bahamas incident.

"We are not talking theory stuff here," Balcomb said in an interview. "The Navy can throw up all kinds of theoretical reasons why it didn't happen. But it happened. There has to be something wrong with the theory. I'm trying to get them to look at the resonance issue."

The Navy's new system, towed by a ship, uses a series of speakers to produce low-frequency sounds that can travel hundreds of miles. Reflected waves are used to locate other ships.

The system would not be deployed close to shore, the Navy says, and operational procedures reduce the chance of a whale being nearby during transmission.