California shark researchers have published a new study on great white migrations, and they say it will help experts and beachgoers predict when young sharks will be near shorelines on the West Coast and beyond.
The migratory habits of great whites have long been a mystery — and that’s especially true of larger adult sharks, Long Beach State University researchers said in a news release on the findings.
But movements of young sharks that tend to stay close to shore are little understood, too, and researchers said their findings shed new light on the kind of habitats juvenile great whites seek. Researchers found that during El Niño years — when the winter water temperatures off Southern California are warmer — young sharks don’t journey south to Baja California, and instead stick around the Los Angeles area or even travel north up to Monterey Bay.
That discovery could help experts tell beachgoers about when the juvenile great whites are likely to be in Southern California coastal waters hunting fish or rays, researchers said.
Researchers completed the study by attaching satellite transmitters to sharks that were accidentally caught off the California coast, then releasing them and tracking their movements.
Chris Lowe, director of the Long Beach State Shark Lab, said in a statement that the study “shows the value of using this technology to predict where juvenile white sharks might show up in the future under changing ocean conditions.”
Lowe said the research revealed young sharks prefer waters in the temperature range of 60 to 82 degrees — and if it gets colder, he said, the sharks will congregate in another habitat, the Orange County Register reports.
“Once bigger, they are now big enough that they are not influenced by temperatures,” Lowe said, explaining the findings only hold true to sharks under 1 year old, according to the Register. “Like a small kid, they get colder in a pool than an adult that has more mass. The bigger they get, the less temperature-sensitive they become.”
Researchers said the findings could also help limit the number of sharks that accidentally get caught in commercial fishing in the future.
“Over time, you can predict where you can expect to see sharks in Southern California and in other parts of the world,” said Connor White, the lead author who completed the research as a graduate student at the university.
The study was published May 8 in the Journal PLOS ONE.
When the researchers looked at the global implications of their findings, they found seven stretches of coastline worldwide that “displayed high degrees of habitat suitability” for the young great whites. That includes the Northwest Atlantic, which comprises “areas off Cape Hatteras, North Carolina, which could be suitable for up to eight months of the year and Long Island Sound, New York, which may provide suitable habitat for six months of the year,” the study said.
The authors wrote in the study that other researchers’ juvenile shark “tracking results from the North West Atlantic indicated that (young white sharks) caught and tagged off New York during the summer spent their first winter months off the outer banks, an area that is highly suitable for (them) during the winter.”
In contrast, researchers said the Southern California coast made a suitable habitat for young great whites eight months of the year, while Baja California waters were appropriate year-round.
“It’s exciting when all the technology — when you put it together with math — start to come together and you can make predictions,” Lowe said, according to the Register. “What makes that important? We can let the public know.”