for National Geographic News
Since 1976, whale expert Ken Balcomb has led what is perhaps the longest running study on killer whales, or orcas (Orcinus orca).
Most days, the research biologist studies orcas from the Center for Whale Research in Friday Harbor, Washington, and from his home porch perched above Puget Sound, where the animals hunt and play in summer months.
But one day last May, Balcomb and whale-watchers along the coast observed something they had never seen before. "I first heard reports from whale-watchers that orcas where behaving very unusually," Balcomb recalled. "One pod had gathered in a tight group and were moving close to shore."
Balcomb confirmed at the time that strange underwater pinging noises detected with underwater microphones were sonar. The sound originated from a U.S. Navy frigate 12 miles (19 kilometers) distant, Balcomb said. The vessel eventually moved within 4 miles (6.4 kilometers) of Puget Sound.
The marine biologist recalled that one pod of orcas appeared agitated and were moving haphazardly, attempting to lift their heads free of the water. "It's like they where searching for some way out of the sound field," Balcomb said.
Dall's porpoises (Phocoenoides dalli) and a minke whale (Balaenoptera acutorostrata) were also seen rapidly moving away from the vessel. In the following weeks an above-average number of seemingly healthy porpoises were found stranded on nearby beaches, according to Balcomb.
Balcomb says he's convinced that the U.S. Navy ships played a role in the destruction. The research biologist is not alone. In recent years whale beachings in the Bahamas, Madeira island, and the Canary Islands have been linked to U.S. Navy sonar exercises.
Exactly how sonar affects the behavior ofand possibly injuresmarine mammals, remains a contentious issue.
A study published last October in the science journal Nature argued that naval sonar exercises could have killed beaked whales in the Canary Islandslocated off northwest Africaby forcing them to surface too quickly, causing decompression sickness, or the bends.
Balcomb said the unusual orca behavior he observed near Puget Sound last year brought to mind a whale stranding that occurred three years earlier in the Bahamas.
At the time 14 beaked whales became beached on the same day that U.S. Navy destroyers where engaged in a sonar exercise. CAT scans of two heads collected from six whales that died confirmed later that the whales experienced hemorrhaging around the brain and ears.
SOURCES AND RELATED WEB SITES