Whale deaths tied to Navy test
- via ndn-aim
Whale deaths tied to Navy test
By Rick Weiss Washington Post, 1/1/2002
WASHINGTON - The mysterious mass stranding of 16 whales in the Bahamas in March 2000 was caused by US Navy tests in which intense underwater sounds were generated for 16 hours, according to a newly released government report compiled by civilian and military scientists.
The report's conclusions mark the first time that underwater noise other than from an explosion has been shown to cause fatal trauma in marine mammals. The military's acknowledgment of responsibility also marks an admission that earlier denials by the Navy were false. The Navy had said there was no connection between its sonar exercises and mass strandings of marine mammals, including the Bahamian strandings.
Specialists said the study, which relied on an elaborate airlift of frozen whale heads from the Bahamas to a Harvard Medical School X-ray facility, places the Navy on notice that it will have to balance more carefully its need to conduct underwater sonar tests against the need to protect marine mammals. The report, approved by Navy Secretary Gordon R. England, concludes that the Navy should ''put into place mitigation measures that will protect animals to the maximum extent practical'' during peacetime training and research efforts.
But the report also allows for the suspension of such protections in the interest of ''national security,'' a broad exemption that has yet to be defined in practice. And it does not answer the contentious question of whether marine wildlife may also be imperiled by a different kind of sonar test proposed by the Navy, one that would involve much lower-frequency sound waves in the ocean.
The latest report, a joint project of the Navy and the National Marine Fisheries Service, grew out of the beaching of 16 whales and a spotted dolphin on Bahamian shores over 36 hours starting March 15, 2000. Seven of the animals - five Cuvier's beaked whales, one Blainville's beaked whale, and the dolphin - died. Ten other whales were pushed back to sea, and their fates are unknown.
The international group that lists threatened and endangered species classifies the beaked whales as being too poorly understood to know whether they are endangered.
The strandings coincided with a nearby Navy exercise meant to improve coordination among ships sailing through enemy-infested channels. The test involved middle-frequency (about 3,000 to 7,000 cycles per second) sonar studies in which underwater noises of about 230 decibels were generated.
For comparison purposes, engineers have calculated that if Luciano Pavarotti could sing underwater, his voice would register at about 173 decibels. Tissue damage in sea animals is known to occur at about 10 times that sound intensity, or 180 decibels (the decibel scale increases logarithmically), and a 230-decibel sonar sound is about 100,000 times louder than that.
The cause of death in the Bahamian strandings may have remained unsettled had it not been for Ken Balcomb, who with his wife, Diane Claridge, runs the Bahamas Marine Mammal Survey on the Bahamian island of Abaco.
''The first whales stranded right in front of our research station,'' Balcomb said last week.
He and others worked furiously to push surviving animals back to sea. But he also knew that studies of the cause of death in previous strandings had been inconclusive because of a lack of preserved tissues - in particular intact whale heads, which can allow careful study of the inner ears and other pressure-sensitive organs.
So when Balcomb and his colleagues heard about two whales that were already dead on the beach, they did not waste any time cutting off the animals' heads.
''We went to the local restaurant and persuaded them to put them in the freezer,'' he said - a big request, as each head was about four feet long and weighed a couple of hundred pounds.
National Marine Fisheries Service scientists flew out to study the beached carcasses.
But to obtain a more definitive diagnosis, arrangements were made with Darlene Ketten, a whale hearing specialist with Harvard's department of otology and laryngology, and the Woods Hole Oceanographic Institute to perform CT scans of the frozen heads.
This story ran on page A2 of the Boston Globe on 1/1/2002.
© 2002 Globe Newspaper Company.
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