Surf Cat

A group of 40 surfers waiting for a wave last week off Linda Mar Beach in Pacifica had a close encounter with a great white shark, estimated at 8 feet long. The shark swam under a woman on her surfboard and then cruised beneath a line of surfers.

A week earlier, that the operator of a drone camera at the same beach sighted great white sharks that were estimated at 6 feet and 12 feet, and posted photos on Facebook.

“The next wave, I surfed the inside of the break, and I thought about my wife and kids,” said Bevan Bell, a filmmaker and surfer who sighted the great white. “I thought how a nip could be the end of it. You don’t have to be chomped. You get bit and you can bleed out.”

Sightings of great white sharks off the Bay Area coast often peak in late summer and early fall. In a domino effect of the marine food chain, the migratory route of salmon to the Golden Gate attracts sea lions, which follow them as prey. In turn, the great whites follow the sea lions. Juvenile great white sharks are fish-eaters, not mammal eaters, but as they get big, likely in the 8- to 9-foot range, they often start looking for bigger prey.

Attacks can occur when a great white mistakes a surfer for sea lion. When surfers in wet suits sit on their surfboards, great white sharks looking up might see the silhouette of what they take for a marine mammal. At the same time, the number of adult great white sharks is also higher than previously thought. A study authored by 10 scientists reported 2,400 great white sharks roam the Bay Area coast, up as much as 1,200 percent from 200 to 400 estimated in the 1990s.

This is most likely linked to the increase of food, or sea lions and elephant seals, and their protected status in the past 30 years, scientists say.

Fatal shark attacks are rare, with only six in the past 20 years and none on the Bay Area coast. But in May, a great white shark attacked a surfer, who later died, at Manresa State Beach near Santa Cruz. The surfer was bit just behind the knee, according to reports.

Shark bites, on the other hand, are more common. At Bean Hollow on the San Mateo County coast, for instance, great whites have twice bit kayaks, according to Chronicle archives.

“Seeing a great white shark is kind of like seeing a bad car wreck,” Bell said. “You’re constantly thinking, ‘It won’t happen to me,’ and it doesn’t stop me from driving. But it is definitely one of those things where you are aware that you are in their territory.”

This latest encounter started last week at Pacifica State Beach, known best as Linda Mar Beach in southern Pacifica, where the shallow contours of the bay help create a break that makes it popular for surfing. In early afternoon last Tuesday, in front of an area called the pumphouse, about 40 to 50 surfers, with 10 or 15 in a cluster, waited at the edge of the surf zone to catch a wave, Bell said. He remembered that the leading edge of a fog layer was just creeping over San Pedro Ridge to the south.

“I was in the lineup, waiting for a good set to come in, trying to gauge where they would break, and if it would be a decent ride,” Bell said. “Just in front of me, 10 or 15 feet, a woman on a board was in a good pocket, but then it was going to break too quick, so she turned and got out of it. I was watching her line, to see if I needed to get out of the way.

“I saw this big gray shape, just under the surface of the water, and that top fin, and the big shark went directly under her. The length of that sucker was like 8 feet. It went right towards her, and as the wave lifted her up (on her board), it literally went right under her.”

Bell said he shouted for the woman to get her legs out of the water.

“I shouted, ‘I just saw an 8-footer go right under you,’” he said. “She never saw a thing. She thought I was talking about the length of her board.”

As it swam off, the big shark propelled itself directly under the nearby lineup of surfers, Bell said.

Other surfers in the area heard Bell’s shark warning, but were not alarmed, he said. One surfer shouted back, “Is it the 6 footer, or the 12 footer? I’m not worried about the 6 footer.” Bell said. “He was clearly already familiar with two sharks in the area.”

Bell said his first thoughts were of his wife, Christine, and his children, Bria, 7, Brixton, 4, and then how to get to safety on the beach.

“I sat there with my head on a swivel, to see if the shark was coming back through,” he said. “I didn’t want to panic and freak anybody out.” Bell said he then caught the next wave and rode in to safety. The other surfers stayed put.

“I felt shock and disbelief,” Bell said. “Out in the ocean, you always know it’s a possibility (to have an encounter with a shark). One of my buddies, Andy, said, ‘If I saw it, you would have seen me walking on water to get to the beach.’”

Tom Stienstra is The Chronicle’s outdoor writer. Email: tstienstra@sfchronicle.com. Twitter: @StienstraTom.