Sea Lion Stranding Caused By Lack Of Food, But Why Remains A Mystery

In the wake of more than 1,000 nearly dead sea lions washing up on the shores of Southern California, researchers believe a shortage of food is causing the phenomenon, but they have yet to pinpoint exactly why it is happening

According to Discovery News, Sarah Wilkin, National Oceanic and Atmospheric Administration (NOAA) marine mammal stranding coordinator for California, recently said experts think an unseen oceanographic or environmental phenomenon is likely cutting the sea lion pups' supply of food, much like El Niño would.

"In the words of some of the other biologists, if this was an El Niño year, it would still be overwhelming but it wouldn't be all that surprising," Wilkin said. Since this isn't an El Niño year, the mystery remains.

Since the beginning of the year, 1,293 sea lions have washed ashore from San Diego County to Santa Barbara County, more than five times higher than the region's historical average, Discovery News reports.

Seasoned adults sea lions may be able to adapt their feeding habits in the face of a food shortage, but pups are more limited in how far they can travel for food and what they can eat. The result is many of them beaching themselves with severely low body weights. Given the age of the sea lion pups, they should weigh at least 50 pounds (22 kg) but many are found on the beach weighing less than half that.

The mass strandings suggest something is awry in the waters, as sea lions are often studied as a gauge of the marine ecosystem.

"Sea lions are usually pretty good at adapting," said Sharon Melin, a wildlife biologist with the National Fisheries Service in an interview with Wired last month.. "If the system starts changing or becomes out of whack, they're the ones that are going to show the signs."

Some have speculated that effects from radiation as a result of the 2011 disaster in Fukushima, Japan as a factor in the sea lion beachings, but Fukushima incident theories are being dismissed for now.

"Radiation is being looked at, just like everything else. We haven't ruled it out, but we really don't suspect this at all," Jim Milbury of NOAA's National Marine Fisheries Service told NBC 7. "We don't suspect radiation because this would also mean other animals in the ocean would be affected, especially in the oceans of Hawaii, closer to Japan, and we haven't seen any of that."