Dozens of grey whales washing up dead along migration route and B.C. is their next stop

An unusually high number of grey whales are washing up dead on West Coast shorelines on their annual migration north and B.C. is the next stop, warns a U.S.-based marine biologist.

More than 20 grey whales werestranded ashore in California this spring, and, further north along the coast in Oregon, several more have washed up recently.

Eleven whales were recently stranded in Washington state. Only one survived.

"We're already beyond what we would typically consider high numbers and this is still early in our stranding season," said Jessie Huggins, stranding co-ordinator for the Cascadia Research Collective.

in one of the longest migrations of any mammal, grey whales migrate from their wintering areas near Mexico to their summer feeding grounds in the North Pacific every year.

"They're heading towards Canada," Huggins told CBC's On The Island.The whales are expected to pass by Vancouver Island.

Food shortage

From necropsies on the animals, Huggins said it appears that food shortage is an underlying cause of the deaths.

"We've been seeing a lot of emaciated animals," she said.

Grey whales feed on small crustaceans that live in sediment on the ocean floor, which brings them closer to shore than other types of whales. Their proximity to land means they are more likely to wash ashore and for their deaths to be noted.

"Many other whales, when they die further off-shore, we never see them," Huggins said.

"Especially skinny ones because they tend to sink first."

Thanks to wildlife protection measures like the Marine Mammal Protection Act, grey whales became a "success story" and their numbers increased over the last decades.

The research hasn't concluded whether the recent deaths are due to a decline in food sources or an overpopulation of grey whales or some combination of both.

"It's difficult for us to tell at the moment, but we do know that, for the last year or two, there have been a number of very skinny whales," Huggins said.

"They didn't get enough food last summer and, along their normal migration patterns, are just not able to make it all the way to Alaska."