Why is There a Rise in Great White Sharks Off the California Coast?
According to a survey, the population of great white sharks off the coast of central California is growing, implying that other species such as seals and fish are also doing well.
A team of researchers identified nearly 300 adult and sub-adult individual great white sharks at Farallon Island, Ao Nuevo Island, and Tomales Point—three locations where the apex predators are known to congregate—over the course of more than 2,500 hours between 2011 and 2018.
A similar study in 2011 discovered 219 great whites, indicating that the population is steadily growing in the region.
“A stable population of white sharks ensures there are healthy populations of the sea lions and elephant seals they feed,” said Paul Kanive, a marine ecologist at Montana State University and lead author of the report, which was published in the journal Biological Conservation.
“This ensures that the lower levels of the food chain, such as fish, are able to sustain the marine mammals.”
Great white sharks and other top marine predators consume a diverse diet, which means they don’t hunt a single prey species to extinction, allowing other species to recover.
The report is the most recent to highlight the significance of stable shark populations. For example, a 2008 study by Oceana showed that a decrease in large shark populations along the eastern coast of the United States was accompanied by an increase in ray, skate, and smaller shark populations, with some species rising tenfold.
The cownose ray was the species whose numbers exploded the most, wiping out almost all of the scallops, oysters, and clams in the region and forcing the closure of a century-old scallop fishery.
“As top predators, sharks help to manage healthy ocean ecosystems,” Oceana said in the study. The oceans will suffer uncertain and catastrophic effects as the number of big sharks declines.”
Kanive and his colleagues discovered many factors that could have aided the recovery of great white shark populations in the region.
California banned great white shark fishing in 1994 and tightened regulations on gill nets, which can catch sharks, dolphins, turtles, and other marine life. The year was 1972. This is a condensed version of the information.