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HomeNewsArchivesEVIDENCE LINKS WHALE BEACHINGS TO SONAR

EVIDENCE LINKS WHALE BEACHINGS TO SONAR

New research findings concerning the mass stranding of whales in the Bahamas earlier this year appear to support theories that the incidents were related to naval exercises being conducted nearby.
In the Virgin Islands, where strandings occurred last August and October, scientists have their own ideas about the possible link between underwater testing and marine life in distress.
A team of scientists working with the National Oceanographic and Atmospheric Administration held a press conference in Puerto Rico on June 14 to report the findings of tissue, bone and organ analyses conducted on six of the seven whales that died as a result of the Bahamas beachings.
Seventeen marine mammals, mostly beaked whales, stranded in mid-March at three different islands in the Bahamian chain. Ten were rescued and returned alive to the sea.
Darlene Ketten, a specialist in "barotrauma," or sound-induced damage, from the Woods Hole Oceanographic Institute in Massachusetts, said all of those examined showed evidence of severe barotrauma – in some cases not only to their ears, but also to their chest and brain cavities.
In recent months, U.S. Navy officials have asked scientists to help look for a link between whale strandings and the testing of the Navy's Littoral Warfare Advanced Development sonar system. But according to Roger Gentry, a coordinator for NOAA's Fisheries Service, the LWAD tests that took place in March didn't begin until five hours after the first strandings were reported.
Ketten says she believe the whales were affected by some sudden occurrence "that could have damaged their auditory systems and possibly the air passages," but she doesn't think the event itself directly caused the deaths.
And while scientists have ruled out more common causes of strandings, Gentry said there may be other answers than the Navy testing. He said the traumatizing underwater sound could have come from the combined sonars of a passing group of merchant ships or might have been caused by a massive underwater landslide.
David Nellis, chief of wildlife for the V.I. Department of Fish and Wildlife, said the conclusions released by the NOAA team were "really kicking the ant's nest as far as the Navy is concerned. If you have barotrauma in organs other than the ears, then you have huge amounts of energy being radiated somehow."
Of the possible scenarios advanced at the NOAA press conference, Nellis said the underwater tests seemed most likely. While an underwater landslide would generate tremendous amounts of sound energy, he said, the effect would be of "a giant hand pushing things in the ocean around." He dismissed the multiple sonars theory as statistically improbable.
Nellis also pointed out that humans, like whales, are mammals and under similar circumstances might also encounter dangerous underwater events. "You wonder what happens when one of those things goes off next to a group of human scuba divers," he said. "Here in the Virgin Islands there are scuba divers everywhere."
The place where humans and the effects of such testing were mostly likely to meet, he said, are the underwater drop-offs a ways offshore where the abundant undersea life attracts divers in search of spectacular views and opportunities to harvest the delicacies of the sea.
Nellis and other V.I. scientists have said they heard unusual underwater sounds around the time of nearby military tests. Yet, he points to one of the mysteries of the Bahamas investigation as the reason an encounter damaging to humans was not likely.
Beaked whales dive so deeply and appear so briefly before the eyes of man that, Ketten said, little is known about them.
Four goosebeak whales stranded last October in the U.S. Virgin Islands (after more than a dozen pilot whales had stranded in the British Virgin Islands in August). Even in death, these marine animals, running 16 to 21 feet in length, proved elusive.
Two of the four were rescued and two died, prompting the Navy to call in the experts, according to Tony Mannucci of the Marine Mammal Stranding Network in Puerto Rico.
In that case, Ketten, one of the experts, said improper handling of the remains made it impossible to conduct body tissue tests. In the Bahamas investigation, however, she said, she was able to recover the hearing organs intact and is now slowly dissolving some of the bony inner portions of the whales' ears in hopes of finding an impression that might have been caused by the phantom sound.
The diving capabilities of the beaked whales led Nellis to suggest that whatever sound event occurred may have taken place far below the ocean's surface. At such depths, he said, sound travels in channels, and only those animals in position at the specific depths would have heard, let alone been affected by, those sounds.
He cited experiences of deep-sea divers hearing a whale song but, upon resurfacing, being told by colleagues who had been shallow diving near the surface that they had heard nothing.
Gentry said more will become known when the Navy releases findings from the March tests in mid-July. Nellis said that, because of the secret nature of military testing, he expects officials will explain some, but not all, of what the Navy was doing in the Bahamas at that time.

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