SAN FRANCISCO — From San Francisco's beaches, the Pacific appears innocuous, rich with bird and fish life. But these are some of the most threatening waters known to man.
The waters are within what some have come to call the Red Triangle, a relatively small piece of ocean known for an unusually high number of great white shark attacks on humans.
The California Department of Fish and Game, which monitors activity by great whites, routinely cautions its research divers about entering Red Triangle waters.
"Our department does not dive in that area unless absolutely necessary," said Robert Lea, a marine biologist and authority on the sharks.
35 Attacks in Region
Records begun by the department in 1926 show 35 shark attacks on people in the area bounded by Point Reyes, about 30 miles north of San Francisco; Monterey, 80 miles south, and the Farallon Islands, about 28 miles west.
Four of the victims were killed.
Of the more than five dozen attacks recorded along all of California and Oregon, the Red Triangle has had by far the greatest concentration and the highest number anywhere in the world, scientists say.
The most recent occurred this month when a 40-year-old surfer suffered cuts on a hand as a great white took a chunk out of his surfboard. In December, a 27-year-old scuba diver was severely mauled near Monterey. He survived and has resumed diving.
John McCosker, director of the California Academy of Sciences' Steinhart Aquarium in San Francisco, offers a simple reason for the unusual number of attacks.
Back in the late 1970s, he predicted an increase in attacks--from an average of one every few years to two each year--because of an explosion in the seal and sea lion population along the West Coast.
Proliferation of Pinnipeds
Protection under federal law since 1972 has ensured a proliferation of pinnipeds, the scientific term for seals and sea lions that means "fin-footed." The Red Triangle's fish-laden waters and shore areas, especially suited for hauling-out and birthing, are perfect for the booming pinniped populations.
McCosker, an ichthyologist and acknowledged authority on the great white shark, predicted that since great whites prey on pinnipeds, their number would increase along with their quarry.
"Unfortunately, it's come true," he said.
In folklore, the great white is recognized as a superb predator, but scientists know little about its behavior since none has survived in captivity long enough for extensive study.
The way it goes in the "Jaws" movies, a great white with malice aforethought stalks the residents of a fictitious East Coast town. In "Jaws the Revenge," the latest sequel, old Pearly Whites even tracks the protagonist Brody family all the way to the Bahamas.
But scientists say that in reality, the beast's interest in man is simply a case of mistaken identity. They occasionally confuse a man in the water with seals, their favorite food.
"It's just a big, clumsy shark--more hungry than aggressive to people," McCosker said.
The great white's sense of smell is acute, but studies suggest that they use vision extensively when hunting. The shark hunts by cruising several feet below the surface, looking for pinnipeds above.
A swimmer may look like a slow seal from the shark's point of view, especially while splashing on the surface where most attacks occur. A meal may be smelled from hundreds of yards away, but when it comes into view, the shark deliberately approaches from the rear before lunging at up to 10 m.p.h. to deliver one massive bite.
Blind During Attack
An instant before contact, the eyes roll back, and a white protective membrane covers the eyeballs. The jaws are thrust forward. While biting, which may take less than a second, the shark is blind.
It was first thought that most human victims survived because they tasted "off" and the shark spat them out. But McCosker said the shark uses a bite-and-spit technique for disabling elusive or dangerous prey, such as the 6,000-pound elephant seal whose own teeth and claws are formidable weapons.
The shark retreats to allow the blood to drain, and returns within perhaps 10 minutes to feed.
"Always dive with a buddy," McCosker advised. "In Northern California, statistics show that you stand a good chance of surviving an attack."