U.S. Navy Sonar May Harm Killer Whales, Expert Says
for National Geographic News
|March 31, 2004|
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.
Roger Gentry, an expert on marine mammal acoustics at the U.S. National Oceanic and Atmospheric Administration in Silver Spring, Maryland, said researchers were unable to confirm whether the damage was sustained when the beaked whales came ashore, or whether it was caused by the sonar itself. But scientists did confirm that the strandings were likely to be linked to the sonar, Gentry said.
Gentry and others have provided the U.S. Navy with a map of beaked whale global hot spots to help mitigate further beaching incidents.
"The problem is that we are seeing military sonar exercises in habitats not used before," Gentry said. "Previously, antisubmarine sonar exercises were carried out deep offshore. But warfare has changed."
The development of ultraquiet, diesel-electric submarines (which have the potential to travel undetected and fire missiles inland) has meant that military drills are required close to shore, Gentry said.
Gentry also notes the need to monitor marine canyonswhich are not only perfect spots for subs to hide in, but also favored habitats of various species of beaked whales.
Gentry concurs that, while most evidence links the negative effects of new sonar to beaked and possibly minke whales, it is plausible that killer whales are also adversely affected by sonar.
Balcomb, the orca expert, filmed the May 5 incident. His footage provides the very first hints that killer whales might react to sonar, commented Robert Gisiner. Gisiner is a marine mammal expert at the Office of Naval Research in Arlington, Virginia.
Gisiner notes that there is a pretty clear correlation between beaked whale strandings and the use of mid-frequency sonar off Madeira (also located off northwestern Africa) and the Canary Islands. "However, we don't really know how the effects on beaked whales occur," he said. "It's hard to say at this stage whether the same thing is happening to killer whales."
Autopsies of porpoises stranded near Puget Sound last May proved inconclusive. But Balcomb said he is fighting, nonetheless, to prove that sonar is dangerous to orcas too.
Next month Balcomb and a group of scientists, naval representatives, and government officials will present evidence on the threat from sonar to the United States Marine Mammal Commission, the Washington, D.C.-based federal commission that provides the President with guidance on the Marine Mammal Protection Act. The hearing is to be the first of three to be held this year.
For more whale news, scroll down for related stories and links.
|© 1996-2008 National Geographic Society. All rights reserved.|