Monterey Bay seeing 'unusual' surge in juvenile white sharks

MONTEREY, Calif. (KGO) -- Young, juvenile great white sharks hugging the shoreline is a common scene in Southern California. For more than a century, the area has been known as the home of so-called juvenile nurseries. They're stretches of beach where the young sharks can feed on fish before they're grown-up enough to hunt large mammals like sea lions. But with a spike in ocean temperatures, their range began to change.

"We had had the warming waters and they started seeing all these juvenile white sharks up here," says Dave Ebert, Ph.D., a shark program director at the Moss Landing Marine Laboratories.

Dr. Ebert and fellow shark researchers first began noticing the juveniles in an area of Monterey Bay, roughly a decade ago. And he says their numbers have not only held steady, they appear to be growing.

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"There'd be days. I'd count like 40 or I just stopped counting about 40. You, you see so many of these six to 8-foot white sharks down there. And that is unusual to see here in Monterey Bay typically," he says.

We first reported the northward migration as researchers were connecting it to an event known as a heat blob. A massive concentration of warm water that peaked off the West Coast in 2014. And while many researchers believe warming ocean temperatures are a driver, they say several factors could be in play.

Professor Chris Lowe directs the shark lab at Cal State University, Long Beach. He says shifts in ocean temperatures are also causing changes in Southern California.

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"Our waters were cold. So we suspect a bunch of sharks left Southern California and maybe some went up there," says Professor Lowe.

While the juvenile sharks are unsettling at first site, experts say they're not the threat to humans that adult white sharks can be. And their increase in numbers could be viewed as a success story, for better management of our marine sanctuaries.

"The marine mammal populations have just exploded along the coast here and of course you bring create a lot more food for these sharks and they're going to start doing what sharks do, you know, mating and giving birth to other sharks. And I think this, what we've seen is an expansion of the nursery area which I think is kind of a good story," says Dr. Ebert.

Experts say the juveniles tend to stay in nurseries until they're about 10 feet in length, and ready to hunt larger prey.