Sea lions are stranded on the California coast, causing concern for their safety among marine biologists. Most of the beached animals are young lion pups, many of whom are starving to death on the beaches.

The National Oceanic and Atmospheric Administration (NOAA) declared an Unusual Mortality Event (UME) in 2013, after more than 1,300 sea lions had to be rescued in the first five months of the year, over five times the normal number. Now, marine biologists believe this season could be even worse for the species.  

Tourists to San Francisco's Fisherman's Wharf delight in viewing sea lions, even if the smell can be unpleasant. Sometimes, visitors will call the National Park Service to report animals stuck on the beach. In January 2015, more than 350 sea lions were rescued from California beaches, a greater number than all of 2013.

"During that year, we had rescued 19 California sea lions in January. This year we already rescued 87 pups in that same month. So this event seems to be much larger," Hendrick Nollens, Sea World San Diego senior veterinarian, said.

Marine biologists are uncertain why the animals are being trapped on beaches. The fact that many of the creatures are young could, possibly, provide a clue. One theory for the beach stranding holds that warming water is driving fish deeper under the ocean. Pups are unable to reach these depths, and could be starving, as mother sea lions spend long periods of time diving for prey. Young sea lions normally don't wean off their mothers until they're 10 or 11 months old.

Other factors may also be leading to a lack of fish, driving movement onto area beaches. The best estimates state there are currently around 300,000 sea lions off the California coast, more than in previous years. This could mean there is no longer enough food to feed all the marine mammals.

"It's a bunch of reasons coming together to pretty much create what we could call a perfect storm," Keith Matassa, executive director of Pacific Marine Mammal Care (PMMC), told the press.

The California Stranding Network, managed by NOAA, works on rescuing and rehabilitating the animals.

Some of the sea lions rescued by biologists are severely underweight, leading to health problems. Most of the creatures are dehydrated, and need to be provided with fluids. After an intravenous drip provides essential fluids, the animals are fed a form of gruel, before they are ready to start eating fish. Biologists need to make sure the animals are back up to a healthy weight, and are able to forage for food, before they are let go back into the wild.

More than 140 people have volunteered to help the animals, and local Girl Scouts have created fleece blankets to keep the animals warm.