The cool but inviting waters of Monterey Bay have long been the nurtured lawn of carefree surfers and relaxing beach goers, and of course seals, seabirds and the occasional humpback whale.
But a few years ago, surprising numbers of young great white sharks began to appear. The summit predators largely coincided with the coast of the community of Aptos and swam so close to the shore that sometimes the long, dark frames of half a dozen large whites could be seen. The summer spectacle, which caught even the best marine scientists off guard, did not disappoint.
In a study published Tuesday, researchers now say they understand why the sharks are there. The young large whites, in another worrying consequence of climate change, found that the hot water of Monterey Bay had become suitable nursing grounds because of the temperature. Historically, they have preferred the mild conditions in Southern California and Northern Mexico.
‘We identified from the beginning that it was not a shark paper. This is a climate report, ‘said Kyle Van Houtan, chief scientist at the Monterey Bay Aquarium and one of the authors of the new study in the journal Scientific Reports. “These sharks, by going to areas where they have not been found historically, tell us how the ocean is affected by climate change.”
By analyzing the location of more than a dozen electronically tagged sharks, the major researchers behind the newspaper found that the preferred range of the animal before 2014 was as far north as Santa Barbara. But after a marine heat wave known as ‘the Blob’ hit the Pacific Ocean in that year, the favorable conditions, characterized by temperature, shifted north to Bodega Bay, and the sharks followed, according to the observations and observations by fishermen and other.
While the Blob largely disappeared, Monterey Bay, and especially the waters near Aptos, remained warmer and more hospitable to the young sharks. The ocean temperatures in the area are about 55 degrees Fahrenheit, but have risen to 69 degrees in recent years.
The juveniles like these warmer conditions because they are smaller than adults, less than 10 feet long and also do not regulate their temperature. They tend to nurse in shallow coastal waters where they feed on fish, skates and rays. Once they are two or three years old and approaching their full size of up to 20 feet and a few thousand pounds, they strive for colder, deeper water, including infamous shark hotbeds such as the Farallon Islands.
The authors of the study say the big whites in Monterey Bay are not very interested in people. In May last year, however, a 26-year-old surfer was fatally bitten, not far from Manresa State Beach in Aptos, one of the few attacks in history.
“You put more sharks in the water, you put more people in the water, your probability of an encounter increases,” Chris Lowe, a professor of marine biology, told California State University Long Beach and co-author of the article. ‘But from what we’ve seen, the sharks seem to be completely ignoring humans. They just do not care. ”
In recent years, heaps of photos and videos taken along the coast of Santa Cruz have shown that unsuspecting swimmers, surfers and paddleboarders come within a few feet of the young sharks.
Many people in the area began to name the waters around Seacliff State Beach in Aptos, characterized by an oil baker and a landmark known as the Cement Ship, ‘Shark Park’. The juveniles from 5 to 9 feet are usually present between April and October.
Gabe McKenna, public safety supervisor at the regional park for state parks, said local lifeguards took note of the increase in sharks and responded accordingly and sometimes posted warnings to visitors and closed a beach on a rare occasion.
“Our water staff is really proactive with all components of water safety,” McKenna said.
Partly because of the increase in the number of sharks, the state provided funding for greater monitoring of the large whites. A pilot program in Southern California that uses transmitters on buoys to alert lifeguards to the presence of tagged sharks is being considered in Santa Cruz County.
Kurtis Alexander is a staff writer for the San Francisco Chronicle. Email: [email protected] Twitter: @kurtisalexander