Ralph Collier, of the Shark Research Committee, identified the shark as a great white and provided the estimate of its size. Great whites can grow to 21 feet long, so it is likely that this individual was a juvenile.
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Ocean Beach surfer Nick Masturzo appears to have been one of the few on the water who spotted the shark.
"I saw it straight on," he told Surfline, explaining that he was paddling over a wave when the shark suddenly surfaced.
"And when I saw that white belly go up and the super-defined white of pectoral fins, I knew what it was," he continued. "I told everyone around me and went in. It was funny: Some people were saying, 'That's not cool,' but I would never say 'shark' on a small day to try to clear the water."
As word got around about the breach, about 30 surfers decided to stay on shore, but another group of surfers took their chances.
Despite the lack of documented shark attacks in waters off the popular beach, the site is 32 miles from the Farallon Islands, a known great-white hot spot. On a clear day, the islands are easily visible from Ocean Beach. The islands are positioned in a highly productive Pacific upwelling region that attracts fish, seabirds, seals, and whales. Great whites are drawn to all of that potential prey.
Luckily, no surfer became prey for the great white.
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Only one individual has died as a result of a shark attack in San Francisco waters, according to a SF Chronicle summary. The unfortunate swimmer was an 18-year-old who, in 1959, was killed by a shark as he treaded water at Baker Beach, a site known today more for its nude sunbathers than sharks.