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An unusually warm patch of ocean is starving thousands of baby sea lions

epa04736361 (11/20) Cara Field, staff veterinarian and Rebecca Green associate veterinarian prepare to sedate a malnourished and dehydrated sea lion pup that have been stranded along the northern California coast receive much need care at the Marine Mammal Center in Sausolito, California, USA, 07 April 2015. Wildlife services in California are being pushed to their limits this year. Since January 2015, every month has set a record in sea lion strandings, mostly sea lion pups, according to the National Oceanic and Atmospheric Administration. EPA/PETER DASILVA PLEASE REFER TO ADVISORY NOTICE (epa04736350) FOR FULL FEATURE TEXT
EPA/Peter Dasilva
Staff veterinarians prepare to sedate a malnourished and dehydrated sea lion pup that had been found stranded along the northern California coast.
By Gwynn Guilford
Published Last updated This article is more than 2 years old.

For months now, emaciated sea lion pups have been mobbing the California coast, looking like furry sacks of bones littering the beach. As of late April, 2,700 of these freakishly skinny pups had been “stranded” ashore—nine times more than the average between 2004 and 2014, according to the California Marine Mammal Stranding Network.

What’s behind the die-off? The “warm blob,” it seems—the huge patch of freakishly balmy sea that bloomed off the California coast starting about a year ago.

To beat the heat, sardines, squid, and other creatures that sea lions typically eat have fled farther offshore or to deeper waters, Sharon Melin, a biologist with the NOAA Fisheries National Marine Mammal Laboratory, told the On the Line podcast.

The warm blob.

That’s made new sea lion mothers swim farther and deeper to find the food they need to produce milk for nursing their pups. During these foraging trips, female sea lions leave their young in their rookery—an island breeding colony—for days at a time. By tracking one of these island populations starting in December 2014, Melin and her colleagues discovered that by March, half of the females had abandoned their pups, probably because their babies were dying. The mothers whose pups were surviving were regularly diving to unusual depths in pursuit of food.

The sea lion pups that have turned up on California’s beaches are those that decided they couldn’t wait for their mothers’ return and ditched the island rookery.

“They’re the ones that finally decide they just have to go to try to find food, but they’re too little and they’re not—they don’t have any foraging skills, and so they get out there in the ocean and they just can’t survive,” Melin said. “And so they end up washing ashore.”

At that point, humans take over the struggle to keep the famished pups alive. About half of the stranded pups taken into care by California’s network of Marine Mammal Centers survive and are released back into the wild; most of those little sea lions make it, the networks says. Here’s a heartbreaking survey of what they’re going through:

Reuters/Mario Anzuoni
Recovering sea lion pups in their enclosure at Laguna Beach’s Pacific Marine Mammal Center.
EPA/Peter Dasilva
Volunteers from the Marine Mammal Center approach a stranded fur seal on Ocean Beach for rescue in San Francisco.
Mendocino County Sheriff via AP
Two Mendocino County, California, police officers pose for a photo with a stranded sea lion pup that had waddled about a quarter-mile from the ocean. (It was later rescued.)
EPA/Peter Dasilva
A volunteer moves incoming malnourished and dehydrated sea lion pups to temporary pens at the Marine Mammal Center in Sausalito, California.
Reuters/Mario Anzuoni
A sea lion pup swims in its enclosure after being rescued at the Pacific Marine Mammal Center in Laguna Beach, California.
EPA/Peter Dasilva
A cart piled with the bodies of sea lions that didn’t make it. The stranding centers are necropsying all deceased sea lions in order to learn more about what’s starving them.
EPA/Peter Dasilva
Sea lion pups stranded in California
EPA/Peter Dasilva
A close-up view of an elephant seal under treatment, swimming at the Marine Mammal Center in Sausalito, California.
EPA/Peter Dasilva
The Marine Mammal Center in Sausalito, California. It has housed 882 rescued sea lions so far this year.

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