Puget Sound orcas presumed dead

Seven killer whales from the endangered population in Washington’s Puget Sound are missing and presumed dead in the most significant die-off of one of the icons of the Pacific Northwest in nearly a decade.

Scientists tracking the black-and-white orcas off the coasts of California, Oregon, Washington and British Columbia said there were signs the whales may have starved to death, though whether that was because of insufficient food or disease that made them unable to eat is unknown.

The number of Puget Sound orcas has declined so much that seven whales represent a significant part of the population, especially because at least one reproductive-age female -- the animals essential for replenishing the pods -- are among the missing, scientists said.

The missing whales came to light during annual photo inventories conducted by the Center for Whale Research in Friday Harbor, Wash., which compiles reports to aid federal scientists in recovering the species, which was listed as endangered under the Endangered Species Act in 2005.

The orca population in Puget Sound had approached 100 in the early 1990s but had steeply declined to fewer than 80 whales by early this decade.

Their numbers were recovering over the last several years -- until now.

“We’ve noticed that the drop is coincident with the crashing of king salmon supplies,” which makes up about 80% of orcas’ diet, said Ken Balcomb III, executive director of the Center for Whale Research.

He said that although salmon stocks in Washington had been in trouble for some time, Puget Sound orcas had been ranging as far south as Monterey Bay in California to feed on the large, fat king salmon -- but now salmon in California and Oregon are under duress as well.

“Coastwide, there’s a [king salmon] problem. They used to be able to swim from Alaska to California and find plenty of fish. Now, nowhere in that range are they finding enough,” Balcomb said.

Scientists from the National Marine Fisheries Service said it is too early to say conclusively that the whales died because they couldn’t find enough fish.

One of the seven whales was a matron in her mid-90s whose death is not surprising. Likewise, calf mortality is not unusual, even though this year two out of three young orcas were among the missing.

“But when you see adult, reproductive-age females die, then you start to get a bit more concerned about what might be going on,” said Brad Hanson, a federal marine mammal biologist.

One of the missing females had been tracked and found to be emaciated. Biologists were able to take a biopsy before she disappeared and will be able to analyze it over the next few months.

“The question is, was the emaciation due to a lack of food because she couldn’t find it, or some disease-type issue that was compromising her ability to feed?” Hanson said. “That’s one of the things we need to look at.”

--

kim.murphy@latimes.com