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Should you freak out if you see a shark? New research gives insight into great white behavior

By day, young sharks like to bask in the warm sun near the ocean’s surface. But as the sun comes up at dawn and dips into the horizon at dusk, that’s when the great white sharks start to really move.

Cal State Long Beach’s Shark Lab researchers recently published an academic paper on juvenile white sharks’ behavior, in conjunction with the University of Minnesota, just as its educational booths, or “Shark Shacks,” start to pop up at local beaches for the summer to teach the public about the predators’ presence in what is their natural habitat.

Marine biologists and researchers across Southern California have been putting a spotlight in recent years on the mysterious creatures as their populations rebound and more sharks are seen off local beaches – especially the young sharks that use the shallower waters near the coast as a nursery.

Sharks like to take it slow during the day and speed up in the early-morning hours and at sunset to feed, according to a paper recently published by researchers with the Shark Lab at the California State University, Long Beach.(File photo by Kevin Sullivan / SCNG)

A few years ago, the younger sharks showed up in big numbers in off the South Bay, Long Beach and along Orange County, though in the past two years the juvenile aggregations – large groups that gather close to shore for extended periods – have moved north into Santa Barbara and south to off San Diego.

The latest research paper details how the Shark Lab team put out high-density acoustic receivers, about 22 of them in a small area, to track movements of tagged sharks at different times of the day. Authored by Shark Lab researcher James Anderson it has been published in the open-access journal PLOS One. 

“We could calculate the approximate speed of the animals and we were able to plug it in and look at their metabolic rates,”  Anderson said.

What they found was so surprising, they ran several different tests to verify their findings.

During the day, the sharks minimized their movement rates – basically sauntering in the sea, swimming really, really slow.

“What we found was during the day, these animals are really just cruising at the surface,” Anderson said. “They bask in the sunshine and go as slowly as possible, not paying attention to anything or anyone.”

But there was abrupt changes in patterns in the early morning and early evening – at dawn and dusk.

“You would see the animals’ speed pick up, drop to deeper depths and colder temperatures,” he said.

It’s believed they were traveling to deeper waters to forage for food, he said, speeding up to keep their body temperature up in the colder waters.

“It became very apparent, this is when the animals are foraging. They are chasing after food,” Anderson said. “The biggest spike was in breakfast time, they load up on food, have a big hearty breakfast and they chill the rest of the day. If they were humans, they’d be hanging out at the beach like beach bums. They are waiting around for the next time to eat, basically.”

That’s different behavior than the larger great whites, the adults and nearly adults that swim at higher speeds at all times of the day and night.

“These guys are minimizing their energy,” he said of the younger sharks.  “They can sit in the sunshine and they are just growing. It’s maximizing their chances to grow and progress to the next life stage.”

That’s important, the paper points out, because it means the juvenile great white nursery habitat off the coastline is key – it is a safe a place they can hide from predators. Even their own parents will eat them if hungry.

A robust habitat means they have a safe haven to find plentiful stingrays and small fish to munch on.

Sharks like to take it slow during the day and speed up in the early-morning hours and at sunset to feed, according to a paper recently published by researchers with the Shark Lab at the California State University, Long Beach. (Photo By Jeff Antenore, Contributing Photographer)
Sharks like to take it slow during the day and speed up in the early-morning hours and at sunset to feed, according to a paper recently published by researchers with the Shark Lab at the California State University, Long Beach. (Photo By Jeff Antenore, Contributing Photographer)

“They can eat well, grow and take shelter from their potential predators and really maximize their potential for success and life,” Anderson  said.

So if a beachgoer sees a fin sticking out of the water, should they freak out?

“These are a large shark species. They will get big, but they are in the juvenile stage,” Anderson said of the young sharks that like to hang out in shallow Southern California waters.

“They are foraging when we are not in the water,” he said, but added, “They are wild animals and unpredictable, you do have to take that into account. It’s better to have knowledge, rather than be ignorant.”

Still, he said, you have more to worry about driving on the 405 freeway than sharks in the water.

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