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Why Hundreds of Starving Sea Lion Pups Are Washing Up in California

4 minute read

There are now so many young sea lions being stranded on the West Coast that federal officials say they can’t keep up. As a result, the National Oceanic and Atmospheric Administration (NOAA) issued some brutal advice Wednesday: If you see a beached sea lion pup, call the authorities, but be prepared for them not to come—at least for a while.

Normally the marine mammal stranding network, a series of facilities dotted along the U.S. coastline, will send staff to take in any seal or sea lion pup found stranded and do their best to rehabilitate it. But many facilities in the network are nearing capacity as sea lions wash ashore at a much higher than average rate. Since Jan. 1, rescuers in California have taken in about 1,000 pups—nearly four times the typical total for the first four months of the year.

“The reality is that we can’t get to all of these animals,” says NOAA stranding coordinator Justin Viezbicke.

Photos: Inside a Hospital for California's Stranded Seals and Sea Lions

Sick Baby Seals Marine Mammal Center
A California sea lion sits on the edge of a pool at the Marine Mammal Center in Marin County, Calif. on May 9, 2014.Corey Arnold for TIME
Sick Baby Seals Marine Mammal Center
California sea lions swim and sit out in the sun while visitors look on at the Marine Mammal Center in Marin County, Calif. on May 9, 2014. Corey Arnold for TIME
Sick Baby Seals Marine Mammal Center
Harbor seal pups wear plastic identification tags that help caregivers tell them apart at the Marine Mammal Center in Marin County, Calif. on May 9, 2014. Corey Arnold for TIME
Sick Baby Seals Marine Mammal Center
Herring breakfasts are organized and labeled for each seal and sea lion at the Marine Mammal Center in Marin County, Calif. on May 9, 2014. Corey Arnold for TIME
Sick Baby Seals Marine Mammal Center
A harbor seal pup wears a plastic "hat tag," used to identify individual animals at the Marine Mammal Center in Marin County, Calif. on May 9, 2014. Corey Arnold for TIME
Sick Baby Seals Marine Mammal Center
A malnourished elephant seal pup looks outside a pen at the Marine Mammal Center in Marin County, Calif. on May 9, 2014. Corey Arnold for TIME
Sick Baby Seals Marine Mammal Center
Volunteers tube-feed a malnourished harbor seal pup at the Marine Mammal Center in Marin County, Calif. on May 9, 2014. Corey Arnold for TIME
Sick Baby Seals Marine Mammal Center
A volunteer restrains an elephant seal pup while the animal is fed through a tube at the Marine Mammal Center in Marin County, Calif. on May 9, 2014. Corey Arnold for TIME
Sick Baby Seals Marine Mammal Center
A shaved patch on the back of a harbor seal shows where blood was drawn during an admit exam at the Marine Mammal Center in Marin County, Calif. on May 9, 2014. Corey Arnold for TIME
Sick Baby Seals Marine Mammal Center
Seals and sea lions released back into their natural habitat are added to annual graduation posters at the Marine Mammal Center in Marin County, Calif., May 9, 2014. Corey Arnold for TIME
Sick Baby Seals Marine Mammal Center
Researchers perform a necropsy on a California sea lion that died of malnutrition at the Marine Mammal Center in Marin County, Calif. on May 9, 2014.Corey Arnold for TIME
Sick Baby Seals Marine Mammal Center
Dr. Shawn Johnson, Director of Veterinary Science, listens to the lungs of a young sea lion under anesthesia at the Marine Mammal Center in Marin County, Calif. on May 9, 2014. Corey Arnold for TIME
Sick Baby Seals Marine Mammal Center
A California sea lion pup undergoes surgery for a lymph node abscess at the Marine Mammal Center in Marin County, Calif. on May 9, 2014. Corey Arnold for TIME
Sick Baby Seals Marine Mammal Center
Students on a field trip learn what to do if they find a stranded seal on the beach at the Marine Mammal Center in Marin County, Calif. on May 9, 2014. Corey Arnold for TIME
Sick Baby Seals Marine Mammal Center
Siobhan Rickert, 18, has been a volunteer at the Marine Mammal Center for four years She is one of a dedicated network of 1,100 volunteers who help run the facility in Marin County, Calif., May 9, 2014.Corey Arnold for TIME
Sick Baby Seals Marine Mammal Center
An elephant seal pup lies in an enclosure at the Marine Mammal Center in Marin County, Calif. on May 9, 2014. Corey Arnold for TIME
Sick Baby Seals Marine Mammal Center
The Marine Mammal Center sits where the U.S. military once had a missile site outside San Francisco, in the Marin Headlands, Calif., May 9, 2014. Corey Arnold for TIME

So what’s going on? Experts at NOAA say that the culprit is rising ocean temperatures. (On a call with reporters Wednesday, a NOAA climate expert said that they do not believe the stranding increase is tied to climate change.) The warm temperatures are somehow affecting the squid, sardines and other animals that are the core diet of sea lions, perhaps driving the prey deeper into the water or farther offshore. So when mothers swim off to forage from the Channel Islands, where pups are weaned every year, they are having to stay away longer before they can come back to nurse. With less frequent nursing, pups are losing weight at unprecedented rates, and experts suspect that these weak, under-grown animals are being driven to look for food on their own before they are ready.

“They’re not really capable of diving deep or traveling far,” says Sharon Melin, a NOAA wildlife biologist. “They’re not really capable of being out on their own.” And so the pups are washing up on shore, emaciated.

The root cause of the crisis, officials believe, is the odd wind patterns that aren’t cooling the ocean like they normally do. They aren’t certain of what’s behind the lack of cold winds, but they believe the patterns are creating a ripple effect through the food chain. The sea lions, at the top of that chain, are signaling that bigger things may be amiss among the larger marine food web. “There are a lot of puzzles here that we’re trying to put together,” says Nate Mantua, a NOAA climatologist. “We don’t understand it. It’s a mystery.”

This is the third bleak year in the past decade for sea lion pups. In 2013, up to 70% of all the sea lion pups born the previous year may have died due to environmental events, according to Melin, twice the amount that might not make it to maturity in a normal year. Officials say this year’s pups appear more under-nourished than any they’ve observed in the past 40 years.

And even when pups get to a rehabilitation facility, they might not make it back to sea. The Marine Mammal Center, the largest facility in California’s stranding network, saved about 60% of the animals who came to them in 2013. “The sea lion pups arriving at the Marine Mammal Center may look like barely more than skin and bones,” says Shawn Johnson, the facility’s director of veterinary science, “but these are the lucky ones.”

The mass strandings have not diminished the overall population of California sea lions, which has been thriving since becoming a protected species in the 1970s. Now around 300,000 in number, NOAA’s Melin says that another factor at work in the current crisis may be that the species is approaching its resource limit in the environment. “Based on what we’re seeing at the colonies,” she says, “we should be bracing for a lot more animals to be coming in.”

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