How common are shark encounters in California? New research uses drone video to find out

2023/06/11

A sign warning beachgoers about shark activity is posted at the top of the trail leading down to Beacon's Beach in Leucadia on July 26, 2019, in Encinitas, California. 

- Hayne Palmour IV/The San Diego Union-Tribune/TNS

How common are encounters between sharks and humans off California’s coast?

According to new research conducted by California State University, Long Beach’s Shark Lab, there’s a surprisingly high amount of overlap between the places people and sharks hang out.

The research team — led by Chris Lowe, professor of marine biology at CSU Long Beach — used drones to document human water activity and shark distribution.

Researchers conducted more than 1,500 drone surveys from 2019 to 2021 across 26 different southern California beaches — going as far north as Santa Barbara and as far south as San Diego.

Water users came into contact with sharks in aggregation sites on 97% of the days surveyed, according to the study, the first of its kind.

The study was published in the Public Library of Science in June of 2023.

“I think people will be shocked by these findings,” Lowe said.

Where were sharks spotted off California coast?

Researchers found that juvenile white sharks spend more than 50% of their time within 110 yards of the wave break. Some were observed as close as two yards from the wave break.

Overlap between sharks and humans was most frequent at beaches in Carpinteria in Santa Barbara County and Del Mar in San Diego County.

“What’s really special about Southern California in particular is that it contains a lot of nursery areas for the juvenile white sharks,” said Emily Spurgeon, research technician.

According to Spurgeon, overlap between sharks and humans has been historically high in areas near the shore that provide protection, food and ideal thermal conditions — especially for juvenile white sharks, which are more thermally sensitive than adult sharks.

Rising water temperatures are increasing the number of sites with perfect conditions for juvenile white shark nursery sites, Spurgeon said.

“We’re now seeing aggregations and nursery sites in Monterey and possibly the Central Coast,” Spurgeon said.

While humans and sharks had the most encounters during the summer on calm, sunny days, such interactions occur all year long, according to the study.

Stand-up paddleboarders had the most encounters with sharks, the study found.

However, because surfers are more common across the coastline, they are the most likely to have encounters, researchers said.

Do frequent shark encounters mean more attacks?

Despite the frequency of human-shark encounters, the shark bite rate has not gone up, according to the research.

Over the entire two-year surveillance period, there were no confirmed shark bites on people in Southern California, the study found.

“We never expected to see so many encounters every day with no incidents,” Lowe said.

Evidence of a growing white shark population and rising public use of beaches for recreation have led to increased concerns about safety.

In 2021, a man died in a fatal shark attack while bodyboarding in Morro Bay on Christmas Eve.

Another man was left with severe injuries after a separate shark attack at Lovers Point Beach in June 2022.

However the Shark Lab’s new research suggests that shark attacks are very rare given the frequency of shark and human encounters.

Spurgeon hopes that the Shark Lab study will provide beachgoers with more context and education on sharks.

“People don’t need to worry,” Spurgeon said.

The state of California’s shark beach safety program also operates out of the Shark Lab and is dedicated to researching sharks and educating the public on how to safely enjoy the beach.

“It’s not just about sharks. It’s about people,” Lowe said. “This study may change people’s perception of the risks sharks pose to people that share the ocean with them.”

For more information go to csulb.edu/shark-lab.

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© The Sacramento Bee