Experts say cause of whale's death may never be known

KLAMATH, Calif. — Scientists say they may never know what caused the death of a gray whale that was stranded for weeks in the Klamath River in Northern California.

Samples taken from the female whale's carcass could take months to process, and even then may not help determine how the marine mammal died, the scientists told the Times-Standard of Eureka.

The whale and her calf entered the river June 24. The calf made it back to sea about three weeks later.

Three weeks after entering the river, the whale's calf swam back to the ocean, but the adult whale stayed, creating a stir among motorists and tourists who crowded the bridge to see her. But after 54 days in the river, the whale beached herself on a sand bar downstream of the bridge on Aug. 16 and died. After scientists conducted the necropsy — an animal autopsy — members of the Yurok Tribe buried her high up on the riverbank.

Scientists who conducted the post-mortem examination didn't see evidence of broken bones or bruises, which might have been caused by a ship strike, said Jim Oswald, communications manager of the Marine Mammal Center in Sausalito.

The skin was showing effects of the whale's long sojourn in fresh water, but scientists don't really know what the animal's condition was in the ocean, he said.

Getting the tissue samples analyzed could take months. Once scientists receive the results, there's still no guarantee they'll know the cause of death, Oswald said.

Looking at the tissues under a microscope can help scientists discover if the whale had a viral or bacterial infection. Examining the heart muscle can determine if the whale had a heart attack, according to Sarah Wilkin, stranding coordinator with the National Marine Fisheries Service.

"One thing that's common is parasites," she said. "They can look at the tissue and actually see signs of a recent or historic infection that may not necessarily be what caused her death."

Scientists also will search for evidence of biotoxins such as domoic acid, often referred to as "Red Tide," as well as human-produced chemicals, Willkin said.

Post mortems on marine mammals in California have produced valuable information on the oceanic environment, Oswald said. A number of years ago, scientists at the Marine Mammal Center did a necropsy on the body of an adult sperm whale that washed ashore and found 450 pounds of netting in its stomach, he said. Even if a cause of death isn't determined, information from the Klamath River gray whale will help other gray whales, Oswald said.

"The gray whale necropsy will be a bonanza for scientists," he said. "There is so much we learn from marine mammals. They're indicators of ocean health because they're at the top of the food chain for the ocean."

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