Navy sonar was loud enough to cause killer whales to flee from the noise in May 2003, when the Everett-based destroyer USS Shoup was conducting training exercises near the San Juan Islands, according to a new report.
The long-awaited report, issued by the National Oceanic and Atmospheric Administration, concludes that sound levels could have affected the whales, but were not great enough to cause permanent, or even temporary, hearing loss.
The latest report contradicts earlier findings by the Navy that the orcas, members of J Pod, seemed unaffected by the sound. The report gives credence to eyewitness accounts from orca experts who said the whales were behaving unusually.
The report comes out as a growing number of marine mammal strandings are being linked to Navy exercises around the world. In most cases, authorities have been unable to determine the cause of the strandings, but scientists are increasing their research into how noise affects marine mammals.
Ken Balcomb of the Center for Whale Research said the Navy and now NOAA have played down the common-sense conclusion that sonar is injuring and killing whales and porpoises.
“The thing that gripes me about this whole subject,” he said, “is that the argument has been drafted in the form of whether there is hearing damage.
“It’s like it’s an industrial job problem – disregarding the observed fact that these animals are fleeing from sources of sound. They are trying to get away, and they are stranding and dying. It is irrelevant whether they had hearing loss if they are dead.”
Balcomb witnessed several beaked whales stranding themselves during a Navy exercise in the Bahamas. In that case, examination of the animals showed tissue trauma consistent with injury from noise.
About the time of the Shoup incident, about 15 harbor porpoises were found dead in northern Puget Sound. A report just released by NOAA concludes that injury from noise could not be confirmed or ruled out.
The report did find that the 15 dead porpoises found from May 2, 2003, to June 2, 2003, was an “abnormally high number” when compared with the average of six per year over the previous decade.
Cmdr. Karen Sellers, spokeswoman for the Navy’s Northwest region, acknowledged Tuesday that the Shoup’s sonar signals were the “dominant noise event” experienced by the orcas in May 2003, but the Navy maintains that the biological significance was minimal. She said the Navy stands by its conclusions that the strandings of the 15 harbor porpoises were unrelated to sonar.
Since shortly after the Shoup incident, the Navy has strengthened its effort to protect marine mammals, she said.
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