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Sound ideas for beaked whales.

Beaked whales, distinguished by the strange, teeth-like protuberances from their lower jaws, have been around virtually unchanged for 30 million years, but are still the least studied large mammal in the world. Found in tropical and temperate waters worldwide, beaked whales are generally shy animals. Their habitat's ocean-depth topography rivals the Grand Canyon and they can stay down for more than an hour, which makes for difficult field observation. "Studying beaked whales is like observing living dinosaurs," says Ken Balcomb of the Bahamas Marine Mammal Survey (BMMS).

In early 2000, BMMS staffers awoke to find three beaked whales stranded on the beach in front of their center. While they were coercing the whales back out into a deep-water channel, BMMS received phone calls about other strandings in the northeastern Bahamas. Within 24 hours, at least 16 whales and one dolphin had gotten stuck on land. Seven animals died; the others were escorted offshore and not seen again. Since cetacean beachings in the Bahamas are rare (one or two animals per year), BMMS suspected that it was related to a naval sonar exercise, a connection unproven at that time.

Balcomb took on the unglamorous task of cutting off the heads of two dead beaked whales for study. Stored in a freezer, the specimens were flown to Harvard Medical School for high-tech CT scans and examinations. The results showed that the whales had suffered severe hemorrhaging in and around their ears. The U.S. Navy then confessed that it had been conducting cat-and-mouse exercises with warships and submarines using tactical mid-range sonar in the Bahamian Northeast and Northwest Providence Channels. The Navy concluded that the presence of the whales in an ocean channel with calm water, which amplifies sound, caused the sonar to damage their ears. As BMMS biologist Diane Claridge explains, "Whales have air spaces in and around their ears like we do that require pressure equalization." Physiologically, the impact of sonar pressure waves on whales is similar to the "bends" that scuba divers sometimes suffer or die from.

In an advisory report issued to the U.S. National Marine Fisheries Service and the Navy, BMMS asserted: "Mitigation of naval activities during peacetime appears to be the only reasonable solution to this problem." While the Navy says it will try to avoid the deadly combination of factors in the future, it is still trying to get approval to deploy its revolutionary Low-Frequency Active Sonar. This system emits far-traveling sounds as loud as a jet engine for more than a minute at a time to find new, quieter submarines. Environmentalists are concerned, and want the project delayed until the potential effects on cetaceans are fully assessed.

This spring, BMMS encountered a family of healthy Cuvier's beaked whales, the species most impacted by the sonar exercises, and one that has been ominously absent since. Claridge says she hopes that, after surviving 30 million years, beaked whales won't be wiped out by underwater noise. CONTACT: Bahamas Marine Mammal Survey, (242) 367-4155, www.oii.net/ecology/eng/dolphin.html.
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Author:Claridge, Rhonda
Publication:E
Date:Jul 1, 2002
Words:504
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