Whale beached days after sonar drill

It's unclear what caused the death

A 15-foot female beaked whale stranded herself on the Outer Banks shore last week and died.

The whale, a nursing mother, had bleeding around both ears, but a scientist who performed an autopsy could not say what caused the mammal to strand.

Navy officials said Tuesday that they had been conducting sonar training exercises about 150 miles offshore of Virginia Beach, Va., about 10 days before the whale beached March 7. They declined to be more specific about the date, citing security reasons.

Sonar, which uses sound pulses to navigate under water, is a hazard to beaked whales, which live deep in the ocean off the continental shelf.

The technology worries many in North Carolina because the Navy wants to build a sonar training range about 50 miles off the coast. Environmentalists, fishermen and tourism promoters all fear that the sonar range would hurt their interests. But the potential harm to whales and marine mammals has generated the most pressure, especially after more than 30 whales beached near Oregon Inlet after a sonar exercise in 2005.

In the most recent incident, the whale's death was accompanied by the beaching of three harbor porpoises on the Outer Banks around the same day.

Aleta Hohn, director of National Marine Fisheries Service program at a federal laboratory in Beaufort, conducted an autopsy on the whale but could not pinpoint a cause of death.

"There was no smoking gun," Hohn said. "There was nothing that pointed to any specific reason why the animal died."

Hohn said the whale, which stranded at Kill Devil Hills, had no unusual external marks that would suggest it had been hit by a ship propeller, and no signs of entanglement with fishing gear.

She said it appeared that the animal came ashore alive because it had bruising on its stomach and abrasions on its flippers from thrashing. It was unclear what happened to the whale's calf.

Tissue samples from various organs will go to a veterinary pathologist for further analysis. But it's often difficult for scientists to tease out what injuries a whale sustained in the ocean and what occurred after it came ashore.

Hohn did note that the whale had bleeding around both ears -- more around one ear than the other. She said the acoustic fat that lines the whale's jaw, which also is used in hearing, was in good shape.

Hohn said about three beaked whales strand on North Carolina's coast each year. She said the stranding of young harbor porpoises is common this time of year and might not be related.

Scientists worry that sonar's loud pulses of sound might physically damage whales' hearing or cause them to modify their behavior in harmful ways, according to a new report by the Congressional Research Service.

The Navy uses sonar to detect enemy craft lurking under water, and it wants to build the sonar range to sharpen its crews' submarine hunting skills. It evaluated potential sites off North Carolina, Virginia and Florida. But it has long favored a patch of ocean 47 miles offshore of Camp Lejeune in Jacksonville. The proposed range is at the edge of the continental shelf and in the path of the warm-water Gulf Stream. Waters there teem with many types of fish, sea turtles, dolphins and whales.

Jim Brantley, a spokesman for Fleet Forces Command, said the Navy had conducted a one-day sonar exercise about 150 miles off the coast of Virginia Beach.

He said National Marine Fisheries scientists can request information from the Navy about sonar exercises if they suspect a whale's death may be linked to sonar, but they haven't done so in this case.

Michael Jasny, a senior policy analyst with the environmental advocacy group Natural Resources Defense Council, which is suing the Navy over its sonar exercises, said a number of beaked whales were found floating dead near the Canary Islands in 2004 a week after a military training exercise 100 miles to the north.

"The fact that the animal was found 10 days later doesn't mean it wasn't affected by the event," Jasny said. "I think we need to await the results of the investigation."

Poorly understood

Andrew Read, a marine biologist at Duke Marine Lab, said scientists are trying to understand why beaked whales might beach themselves after being exposed to sonar.

"We still don't understand the causal mechanism, ... which makes it very difficult to determine whether an animal that is on the beach is on the beach because of sonar," Read said.

Peter Tyack, a senior scientist at Woods Hole Oceanographic Institution in Massachusetts, has researched beaked whales. He said this case didn't sound like the usual pattern of sonar linked to whale strandings.

"Most cases I'm aware of are quite tightly linked in timing," Tyack said. "Within a few hours of a sonar exercise, you get this pattern of quite a few animals hitting the beach."