Blind sea lion dies
June 17, 2008 · Updated 2:17 PM
The California sea lion found April 4 on Blind Bay Road on Shaw Island has died.
The female sea lion was found dead April 25 in her pool at Wolf Hollow Wildlife Rehabilitation Center. Staff members had named her Virga, the word for rain that evaporates before it hits the ground.
Joe Gaydos of the Sea Doc Society and Amy Traxler of the Whale Museum conducted a necropsy that day at U.W. Friday Harbor Labs. Virga's brain is being sent to a pathologist on Monday to determine the cause of death, Traxler said. Virga's pelt will be sent to a taxidermist and used by the Whale Museum for educational purposes. The rest of her remains were returned to the sea.
Traxler said the cause of death should be determined within a couple of weeks.
Shaw Island residents found the sea lion and called the Marine Mammal Stranding Network. The sea lion was was taken to Wolf Hollow for treatment. An examination determined she may been temporarily blinded by exposure to domoic acid, a toxin in forage fish.
Virga showed considerable health improvement in her 21 days at Wolf Hollow, even regaining her sight. She was described as being about 3 years of age, old enough to give birth to a pup, and she weighed about 150 pounds.
"We were kind of shocked," Wolf Hollow Director Natalie Brandon said of the sea lion's death. "She had been doing very well and had shown no signs of seizure. She was gaining a little bit of weight, she played, she was very responsive."
Penny Harner, a wildlife rehab specialist at Wolf Hollow, said Virga may have had a seizure before she died. Vomit was found on one side of her pool and she had bitten her tongue.
About domoic acid
Domoic acid is a naturally occurring biotoxin produced by the diatom species Pseudo-nitzschia. The toxin is concentrated in small forage fish like anchovies that the sea lions eat. It is a common occurrence off the coast of California but, like the female sea lion, is a rarity in the San Juans.
In an earlier interview, Gaydos said the sea lion was likely exposed to the toxin a while ago, maybe even off the coast of California. Because domoic acid can damage the brain permanently, animals can have periodic seizures and post-seizure blindness long after exposure. The sea lion is currently being monitored round the clock for seizures and other symptoms.
Humans exposed to domoic acid by eating contaminated shellfish get amnesic shellfish poisoning, which causes short-term memory loss, brain damage and even death in severe cases.
It's just one more example of how human health and wildlife and marine ecosystem health are tightly connected, Gaydos said.