Beachgoers receive a warning after an apparent sighting of great white sharks near Half Moon Bay.
The sighting of what appeared to be great white sharks off the San Mateo County coast Thursday prompted warnings to beachgoers to watch their backs this weekend. The sharks were first seen by pilots flying near Half Moon Bay — and there may be more shark spotting on the way.
Scientists say that since 2014 water temperatures in the area have been slightly warmer than usual, which is allowing younger great white sharks that are historically more common in Southern California to move farther north.
Great white sharks are most numerous off the Bay Area coast in late summer and fall, when adult sharks return to the area to feed at the Farallon Islands after their migration to the deep ocean. Local sharks feed on elephant seals and other marine mammals in the socalled Red Triangle, between Monterey Bay, the Farallon Islands and Bodega Bay, usually from about August to December.
In the past few years, scientists have observed more young great white sharks— which eat fish, as opposed to older great whites, which eat mammals — in the area beginning as early as April. That means there’s likely ample food for the sharks.
“All the little white sharks we’ve been seeing in Monterey tells me the habitat is expanding due to a lot of food and a healthy marine environment,” Pacific Shark Research Center director David Ebert said.
There have been other recent Bay Area sightings. In March, a man riding a personal watercraft at Mavericks, the surfing spot just north of Half Moon Bay, saw a large great white shark near a group of people surfing. He towed eight surfers back to safety on the shore. Last month, the Sonoma County Sheriff ’s Office postponed water training in Bodega Bay after a great white shark was spotted by a crew in a helicopter.
Scientists who study sharks and reviewed images from Half Moon Bay agreed that the sightings this week were most likely of young great white sharks.
Christopher Lowe, director of the Shark Lab at Cal State Long Beach, said that if he were a betting man, his money would be on the great white shark as the species sighted.
“The pointed nose, the big pectoral fins that are a bit more forward, and the really triangular dor fin make it look white sharklike,” he said. “On the other hand, the body shape looks a little short and compact, kind of like a salmon shark. But that could just be distortion from the water in the photos, so it looks to be a white shark.”
If not great white sharks, experts said these are either salmon sharks or mako sharks, both of which are relatives of great white sharks. However, salmon sharks — which eat only fish — have a white patch that these sharks appear to lack, and mako sharks are generally a different color.
“From the pictures that I’ve seen it’s really hard to say with 100% certainty that they’re white sharks, but it’s the most likely scenario given the number of white sharks we’re seeing right now in Monterey Bay,” said Salvador Jorgensen, senior research scientist at the Monterey Bay Aquarium. “And the behavior seems similar to that of the sharks in Monterey Bay — they’re swimming at the surface near the shore in warmer water. White sharks typically mill around in the surface waters in the afternoon when the water is the warmest.”
Experts stressed that the young great white sharks that do not migrate to the deep ocean and are off the coast in the Bay Area now are fisheating. The mammaleating adults will be far out in the Pacific between California and Hawaii until they return to California beginning in late August.
“What I want to emphasize is juvenile white sharks are fish eaters,” Stanford marine scientist Barbara Block said. “They’re not really of the ilk that are dangerous to humans.”
Block’s colleague at Stanford, research scientist Taylor Chapple, said great white sharks are not a danger at this time of year.
“I am a surfer; I’m in the water most days,” Chapple said. “You have a lot more risks on the way to the beach than you do in the water.”
Jorgensen also cautioned against Hollywoodstyle shark hysteria: The number of shark attacks in California each year has been steady at around three or four since 1950, despite rising human and shark populations, and despite an increase in the number of people who are in the water due to wetsuits and the growth in the popularity of water activities like kayaking and paddleboarding.
Still, Ebert said swimmers and surfers should be cautious in the water and listen to warnings from officials.
“If the lifeguards or sheriffs are issuing a warning because there are white sharks, just get out of the water,” Ebert said.