500 starving sea lion pups have washed ashore along the California coast since the start of 2015

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Sea lion pup.

Starving sea lion pups have been washing ashore along the California coast for the past three winters and experts have very few clues as to why this is happening.

"They're extremely emaciated, basically starving to death," Shawn Johnson of the Marine Mammal Center in Sausalito, California told National Geographic.

Since the start of the year, almost 500 pups have been admitted to the state's rehabilitation centers, with the Sausalito facility handling 171 cases so far. Last year, it took until April for the center to hit the 100-case mark.

Officials said they are particularly concerned because they've yet to hit the peak stranding season, which is traditionally a few months away.

"We're all kind of holding our breath," said Justin Viezbicke, stranding network coordinator for the National Oceanic and Atmospheric Administration (NOAA).

Canaries of the sea

Sea lions are sort of the "canaries in the coal mine" for ocean health and an unhealthy population usually means that something has gone wrong. Unfortunately, scientists aren't sure exactly what that might be.

Scientists have mentioned that the stranding pattern was similar to that of significant El Niño years, when warm waters replace the cool, nutrient-rich waters that typically fuel the area's production. However, these aren't El Niño years.

In addition to the struggling pups, nothing else has been clearly wrong, with not one other species likewise affected. Also, adult sea lions looked fine.

Theories

So far, scientists have eliminated known diseases and ecological toxins, which might be likely to affect greater than just pups. Some scientists question if the sea lion population has grown so big that the offshore environs simply can't support their numbers.

The most popular theory appears to be that changes populations of sardines and other sea lion prey are forcing nursing sea lion mothers to go farther in trying to find food. These extended forays keep sea lion mothers away from their pups. This could cause the small animals wait on the beaches and go without food until they ultimately go out their own, well before they're ready to handle the Pacific Ocean.

NOAA teams are out on the Channel Islands, investigating the sea lion population and attempting to fill in the knowledge gaps.

One thing that scientists have seen come out in the last year is a substantial, prolonged spot of warm ocean water that has established offshore and may be bumping the ecosystems of western North America out of whack.

"It's been a really unusually warm year, and disruptive to the normal marine food web, from Baja all the way up to Alaska," said Nate Mantua of NOAA's Southwest Fisheries Science Center.

Mantua noted that wind and weather patterns in 2014 generated patches of warm water from Mexico to Alaska. Those patches then merged, forming a large pool that experts think may hang around for awhile.

The NOAA researchers emphasized that it is too soon to tell if the warm-water pool is affecting the sea lions, or if the pups are a harbinger of something else going on beneath the waves.

Chomsky: We Are All – Fill in the Blank.

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