Sonar pulsing from a Navy guided-missile destroyer during training exercises near the San Juan Islands two years ago was likely loud enough to send killer whales fleeing, according to a government agency report.
The National Marine Fisheries Service report backed up local experts who said sonar from the USS Shoup caused a group of orcas to behave abnormally, apparently trying to avoid the sound.
It contradicts the Navy’s previous findings that orcas in Puget Sound’s J Pod seemed unaffected by the sonar coming from the Shoup on May 5, 2003.
NFMS’ 10-page report, dated Jan. 21 but not released publicly until March 10, said the Shoup’s sonar was not loud enough to cause the whales any temporary or permanent hearing damage.
Cmdr. Karen Sellers, the Navy’s spokeswoman for the Northwest, acknowledged the Shoup’s sonar signals were the “dominant noise event” experienced by the orcas that day. She said the Navy maintains the “biological significance” was minimal, The (Bremerton) Sun newspaper reported Wednesday.
Ken Balcomb of the Center for Whale Research in Friday Harbor said whether the whales suffered hearing loss is beside the point.
“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 said.
Marine mammal researchers have also expressed concern about 15 harbor porpoises found dead in northern Puget Sound in the spring of 2003. Sellers said the Navy stands by its conclusions those deaths were not related to sonar.
The NMFS report said scientists found no signs the porpoises’ ears suffered any acoustical trauma, although decomposition hindered researchers’ analysis.
Puget Sound’s orca population has been proposed for listing under the federal Endangered Species Act.
Strandings of marine mammals in other parts, including the East Coast and the Caribbean, have led to speculation that sonar from ships might be to blame.