By Kiet Do

APTOS, Calif. (KPIX/CNN) - Scientists are investigating why several hundred dead squid have washed ashore along California beaches.

The beaches of Santa Cruz County are littered with carcasses of thousands of Humboldt squid. They've stranded themselves from Aptos to Watsonville, a span of 12 miles.

"You just see them essentially killing themselves and it's just really weird to see," said Hannah Rosen with Hopkins Marine Station.

It happened during high tide. Some people actually tried to put them back in the water, but Rosen says the deepwater creatures swam right back to shore.

"They don't see the shore very often, so it might just be that they don't understand what's going on around them, and they're just trying to get away and don't realize that if they swim towards the shore, they're going to run out of water eventually," she said.

They're juveniles, both male and female, about a foot and a half long, weighing roughly three pounds each. They had full stomachs, having feasted on smaller market squid. A few had also cannibalized each other, which is normal.

Researchers have no idea why this is happening, but they think it's because the squid have eaten toxic algae.

"It's possible that the squid are ingesting either these neurotoxins or they're getting it through their food, and that could be causing them to be disoriented and swim onto the beach," said Rosen.

Humboldt squid have not been seen in the Monterey Bay area for a few years.

Scientists believe El Nino weather patterns may have drawn them to the cooler waters of northern California.

This is the third stranding in six weeks.

"It's really an exploratory time for us, so we're learning more about what causes these strandings, and whether or not we should be worried about them or if it's just a natural part of the squid cycle," said Rosen.

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