Scientists hope necropsy data will reveal cause of gray whale deaths

SAN FRANCISCO (KGO) -- Over 70 gray whales have washed up on the North American west coast this year, in what NOAA officials have declared an "unusual mortality event."

Fourteen of those whales have appeared in the Bay Area.

Bay Area scientists spoke about the work they're doing to find out the reason behind the spike in whale deaths.

The San Francisco chapter of the American Cetacean Society hosted Tuesday night's presentation with biologist Moe Flannery of the California Academy of Sciences.

Her team, along with the Marine Mammal Center, have performed 12 necropsies of gray whales this year.

Ship strikes are a major concern, but the leading cause of death is malnutrition. Scientists say could be due to a multitude of factors, including climate change.

Gray whales only feed in Alaska during the summer and then migrate to Baja California in the winter to find warm waters to give birth. It's one of the longest known migration patterns in the world.

"For some reason, and we don't know why they may not have enough nutrition to make it all the way back to Alaska," said Flannery. She pointed to the short food supply, poor quality of food, a larger population of gray whales, or an unknown disease as some possible theories for malnutrition.

Scientists say the unprecedented amount of data they have collected from necropsies this year will help find an answer. There was a similar death event involving whales 1999-2000. Hundreds of gray whales stranded along the west coast in two years, but only two necropsies were performed. Modern marine biology infrastructure has allowed scientists to access more specimens.

"Hopefully the increased data we can collect this year, including folks in Washington and Alaska, we'll be able to add more data and really look at the question," said Flannery.
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