Decomposing carcasses of five additional whales -- one fin whale and four humpbacks -- have been reported by fishermen, pilots and survey crews, said Kate Wynne, a marine mammal specialist with the Sea Grant program at the University of Alaska Fairbanks. Those reports came in over the past several weeks, and all the whales appear to have died at about the same time, said Wynne, who is working with her colleagues to investigate the deaths.
So far, the only sample taken from any of the dead animals has been from a single dead fin whale that was already partially decomposed when it came ashore, Wynne said in an email Friday. Results from one test came back negative for domoic acid, a toxin that is produced by algae and accumulates in shellfish, Wynne said. Results from other tests are still pending, she said.
Gulf of Alaska waters have been warm recently, and one theory is that the whales encountered some kind of toxin related to warmth-induced harmful algal blooms. But so far, Wynne said, that has not been proven.
"We do not have conclusive evidence to link their mortality to algal blooms but continue to sample water/plankton/shellfish with a network of folks statewide," she said in her email. "Hopefully, by monitoring current conditions and tracking/recording carcasses, we will be quicker to note and respond to a future event if it happens."
The first dead whale was spotted on Memorial Day weekend. Scientists from UAF's Sea Grant program and the National Oceanic and Atmospheric Administration have been trying to find an explanation for the unusual event.
Wynne said it's possible the toll could still rise. "The number of now-rotten carcasses may continue to climb as more people travel around the area and submit reports of carcasses they see," she said.