It might come as unwelcome news to swimmers and surfers, but great white sharks appear to be mounting a comeback off California.
"I think there are more sharks," Christopher Lowe, a professor at Cal State Long Beach and director of the university's Shark Lab, said during an exclusive phone interview. "And that's not a bad thing; it's a good thing."It's the first declaration by a prominent shark researcher that a recovery of the embattled great white shark -- the world's most notorious predator -- seems to be occurring.
A longstanding statewide ban on fishing for white sharks, an increased survival rate among young white sharks because of fishing gear restrictions, and an expanding sea lion population as a prey source are chief reasons for the comeback.
Lowe, who has performed extensive tagging of juvenile white sharks off Southern California and has pored over data dating back generations, said personal observations and increased incidental catch rates of small white sharks by commercial fishermen help support his contention.
Salvador Jorgensen, leader of the white shark research team at Stanford University's Hopkins Marine Station, did not disagree with Lowe's assessment but was more guarded when asked for a response.
"If what we are seeing is truly an increase in the white shark population that would be a relief," Jorgensen said. "Currently we are finding that the total number of adult white sharks along the west coast of North America is much smaller than many people expected."
While the prospect of great whites multiplying off the Golden State might trouble beachgoers, particularly in the middle of summer, Lowe said he does not believe a growing population would result in more attacks on humans.
Southern California is a nursery area for juvenile great whites, who feed on small fishes, rays and other sharks during the summer months. Some of these sharks, measuring to about seven feet, are seen each summer by beachgoers.
There have been only eight fatalities attributed to white sharks off California dating to 1926, according to the University of Florida's International Shark Attack File. The last fatality involved an attack by an adult white shark on a swimmer off a northern San Diego County beach in April 2008.
White sharks are found in all major oceans and "red-listed" by the International Union for Conservation of Nature as a globally threatened species. The California Department of Fish and Game banned fishing for white sharks in 1994 because of concern for their survival.
Jorgensen said a joint population study of adult white sharks by Stanford University, U.C. Davis and Montana State University is still under peer review, so he could not volunteer a number. Lowe and his colleagues also have produced a scientific paper under review, supporting a recovery. "Like Sal, I'm a little hesitant to reveal too much until the paper is fully accepted, but I think the data look pretty strong," Lowe said.
Adult great whites congregate each fall near elephant seal rookeries off Central California. A separate population gathers during the same period at remote Guadalupe Island west of Baja California.Among the threats white sharks have faced globally are trophy hunting for jaws and teeth -- which became widespread after the release of the movie "Jaws" in the mid-1970s -- and commercial fishing for fins and flesh.
It almost seems implausible, in an era during which so many species of sharks are overfished and believed to be in decline, that any species could mount a comeback.
But considering the changing landscape off California, a comeback and its timing make sense. The ban on fishing for white sharks -- for sport or commercially -- was imposed in 1994. That same year, voters approved a measure outlawing the deployment of gillnets within three miles of the California coast.
In Southern California, this zone is where juvenile white sharks spend the summer preying on small fishes, rays and other sharks, before swimming into warmer Mexican waters during the winter.
White sharks are still being caught unintentionally beyond the three-mile mark -- The increase in these captures is what helps support evidence of a comeback -- but those sticking closer to shore are no longer imperiled by the indiscriminate nets, until they venture into Mexican waters.
Adult white sharks, meanwhile, now have a seemingly endless bounty of sea lions on which to prey, along with the elephant seals they prefer.
Sea lions, once routinely slaughtered by fishermen, were spared under the Marine Mammal Protection Act of 1972. Ten years later, their population was estimated at 145,000 in a range from the Sea of Cortez within Mexico to British Columbia, Canada, with only 50,000 in the Southern California Bight.
According to the most recent National Marine Fisheries Service estimate, there there are at least 238,000 sea lions in U.S. waters, the majority of which reside off Southern California.
"So if you add those two things together, you've got a restored forage base for the adults and you've got better survivorship of the pups," Lowe said. "So what we think we're seeing from the fishery catch data and some of the other anecdotal pieces, is the actual recovery of the white shark population."
The biologist added that while Southern Californians should not expect a spike in shark attacks on humans, those who spend lots of time in or near the ocean might witness more sea lions with bite marks, and more surface attacks by white sharks on the pinnipeds.
"I think the white shark population is going to do what it's supposed to do: help regulate marine mammal populations," Lowe said, explaining that apex predators play a vital role in maintaining a healthy marine ecosystem.
To be sure, fishermen whose livelihoods are threatened by pesky sea lions, which decimate catches and destroy gear, will cheer alongside marine conservation groups for more signs of a white shark comeback.
Swimmers and surfers? They're probably not so enthusiastic.
-- Pete Thomas
-- Images courtesy of Christy Fisher / Sharkdiver.com
Editor's note: A version of this post also appears on the GrindTV.com outdoors and surf blogs