Porpoise deaths still a mystery
July 3, 2008 · Updated 3:21 PM
When carcasses of harbor porpoises washed ashore on Whidbey, Fidalgo and San Juan islands last May, many people wondered if Navy sonar tests from the destroyer USS Shoup in the Haro Straits hours to the north of Whidbey might have killed the marine mammals. Now, a just-released report reveals no clear cause of death in 11 bodies that were collected and put through a wide range of tests.
While a group of scientists from around the country analyzed the results of tests and found there was no definitive signs of acoustic trauma in any of the porpoises, the possibility of acoustic trauma as a contributory factor in the mortality could not be ruled out, according to a report released from National Oceanographic and Atmospheric Administration.
We will simply never know what might have killed those animals, Brian Gorman, a spokesman for NOAA, said during a telephone interview Tuesday.
Gorman said two of the porpoises were probably killed by blunt force trauma which could have been caused by the animal hitting a boat or other large, hard object. But no ones knows surely if sonar panicked the porpoises and caused them to be disoriented, Gorman said. A panicked animal could have strayed into the path of a boat or barge.
The Navy made its own independent study of the Shoup incident, said Lt. Anne Cossitt, assistant public affairs officer for Navy Region Northwest.
The Navy is pleased its report and the NOAA report found no direct evidence of acoustic trauma, Lt. Cossitt said.
The thorough studies of strandings before and after May 5, (2003) were not able to draw a connection between porpoise strandings and the Shoups activities, she said.
Gorman and Brent norberg, also of NOAA, emphasized that the scientists reports could not exclude or find any definitive evidence linking the deaths to acoustic trauma. Both pointed out that many times, acoustic trauma is hard to detect in carcasses that have been badly scavenged, like the ones at Admiralty Head and Lagoon Point on Whidbey Island.
In spite of the thorough reports, local environmentalists want to know more.
Sandy Dupernell and Susan Berta are members of Island Countys Marine Mammal Stranding Network. Dupernell, a WSU/Island County Beach Watcher, responded to the porpoise which came ashore at Admiralty Head.
I pulled the porpoise from the water and it was bleeding from the eyes and blowhole, Dupernell said. Im disappointed that an exact cause of death wasnt found. At least acoustics werent ruled out.
Berta responded to the porpoise at Lagoon Point.
Im disappointed but not surprised no cause of death was found, she said. Its difficult for one branch of government to investigate another branch.
Berta also said she found it odd that the Admiralty Head porpoise which was bleeding, did not receive a CT scan which might have provided other information.
I definitely have more questions, she said.
Berta, Dupernell and any other people interested will have a chance to question one of the researchers involved in the testing. Brad Hansen of NOAAs National Fisheries Service will be at the Ways of Whales workshop Saturday, Feb. 14, in Coupeville. His presentation will be on harbor porpoise and he will provide an overview of harbor porpoise as well as discuss local strandings. For more information on the workshop, see page A14 of todays Whidbey News-Times. To report stranded marine mammals, call 1-866-ORCANET.