Maybe you thought this was a happy day for sea lions, but sadly, for sea lions not exposed to pop music of the '70s and '90s, it has been a tragic 2013. Federal wildlife officials declared an "unusual mortality event" as hundreds of stranded and underweight sea lion pups have been washing up on the shores of Southern California.

In L.A. County, almost 400 baby sea lions have washed up onto shores since January 2013. The number was just 36 this time last year. As of about a month ago, there have been 214 stranded sea lions in San Diego County, 189 in Orange Country, and 108 in Santa Barbara County.

With record numbers of small sickly pups, marine mammal centers have been packed as they try to save the animals from problems often more complicated than malnutrition. The increased number of stranded pups has bewildered researchers.

A wildlife biologist with the National Marine Fisheries Service, Sharon Melin, told the LA Times that this spike in stranded pups is a perplexing and disturbing anomaly. Usually, a rise in this many sickly animals would be the result of warmer ocean temperatures (like those during El Niño) or a disease, but "what's different about this incident is we don't have any of that."

Because of their young age (most of the pups are about 6 to 8 months old), they should still be with their mothers. It could be that they were abandoned as their mothers had to go further out to sea to look for food, leaving their pups to fend for themselves, says Melin:

"They're just not capable at this age. They can't dive deep, they're not very efficient swimmers. They're not old enough and big enough to be out on their own. They're really naive and trying to make their way."

[LA Times, image via Getty]