California Great White Shark Population Grows Off Central Coast

Great white sharks are being spotted in waters off the coast of San Luis Obispo County in greater numbers than ever before, marine experts say, though they differ on the cause of the population surge.

“Your part of the coastline is becoming more important to white sharks than we thought in the past,” said Chris Lowe, director of the CSU Long Beach Shark Lab.

This population increase means shark sightings by Central Coast residents and visitors are becoming “more common,” according to Mike Harris, a sea otter biologist who works for the California Department of Fish and Wildlife.

“There are pretty frequent sightings, from people on boats to people in the water surfing,” Harris said. “We had a credible sighting here at Morro Rock (Wednesday).”

Local interactions between sharks and humans have even made headlines over the past few months.

In early July, a pod of 50 leopard sharks were filmed swimming near bathers at Pirate’s Cove near Avila Beach. The video quickly went viral.

In June, a swimmer was bitten by a shark near Pacific Grove and suffered serious injuries before being rescued by good Samaritans. And in December, a boogie boarder was killed in a shark attack off Morro Bay.

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Mike Harris, senior environmental scientist with the California Department of Fish and Wildlife, spoke about the latest sea otter counts and population health on September 24, 2019. The numbers have been trending down in recent years due to Sharks. David Middlecamp [email protected]

Why are more sharks spotted along the central coast?

According to Lowe, researchers don’t fully agree on why populations of great white sharks — which he said researchers prefer to call great white sharks — are increasing along the central coast.

He has been tracking great white sharks for decades by examining shark tagging data, drone sightings and animal carcasses.

Lowe believes the change is partly due to climate change, which has resulted in warmer waters along the central coast.

Rising seawater temperatures off the coast of SLO County have made these areas tolerable for juvenile white sharks, Lowe said. The young frequent the shallow waters as they learn to hunt for food.

Warm water discharged from the Diablo Canyon power plant near Avila Beach also brings larger white sharks closer to shore, he said.

Lowe said the hot water released by nuclear powerhouse has formed what researchers call a “spa” where up to a dozen adult and juvenile great white sharks hang out before returning to open waters to hunt.

This kind of behavior is not normal for the species, he noted.

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Kayakers caught a large shark while fishing off Cambria in August 2019. Peter May Courtesy

Usually, says Lowe, great white sharks “don’t like to be close together. And even though it’s a small space for them, it’s amazing how many people are crammed into this space.

“We think the reason they do it is so they can warm up for a week. Then they can go elsewhere to feed and come back to warm up.

This allows the sharks to grow faster,” he explained. “They save energy and then can feed along that part of the coast where there is plenty of food.”

An increase in conservation efforts to protect Marine species such as sharks, seals and sea lions in recent decades have also played a “big role” in the increase in white sharks in the region, Harris said.

“There is more food available for white sharks,” Harris said. “And we have protective measures in place to protect the white sharks, which I think add up to support the success and survival of the white sharks and increase their numbers.”

Will it bring more shark attacks?

As more juvenile sharks settle on the central coast, Harris said, there has been an increase in sea otter deaths from shark bites, especially in areas such as Morro Bay, Pismo Beach and Estero. Bay.

Sea otters aren’t a food source for great white sharks, but juvenile sharks in the area sometimes bite otters when they mistake them for seals or sea lions, Harris said.

Harris said more than half of the sea otter carcasses he salvages in parts of SLO County show bite marks from great white sharks.

“This eliminates enough sea otters to stall sea otter population growth and expansion,” Harris said.

While this presents challenges to meeting sea otter conservation goals, he said it could lead to “More of a natural balance.”

A baby sea otter cuddles with its mother while floating in the calm waters of Morro Bay near the southern ‘T’ jetty. Danna Dykstra Coy

Although more and more sharks are sharing the water with sea otters as well as swimmers, surfers and kayakers, Lowe said people shouldn’t expect an increase in the number of attacks from large white sharks against humans.

He said evidence from Southern California shows that bite rates actually go down on a per capita basis, even when there are more sharks swimming next to people.

“We think the sensory abilities (of sharks) are good enough that they can tell the difference between people,” Lowe said, adding that ocean predators may even learn to recognize people better due to close contact. they have with humans.

Harris said people should continue to enjoy the ocean despite the possible presence of more sharks.

“White sharks tend to elicit a fear response,” Harris acknowledged.

“People just have to be aware that when you enter the ocean, you enter a wild environment, and sharks are part of that,” said Harris, who surfs locally. “It’s really not much different from hiking in the wilderness. There are also predators in these environments. So just be aware of your surroundings, know that you are entering a wild space where these animals are, and still enjoying it.

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Mariana Duran is a reporting intern at the San Luis Obispo Tribune. She is a double major in Media Studies and Cognitive Science at Pomona College.