GLEN JUSTICEA display at San Francisco's Aquarium of the Bay shows how similar seals and surfers may look to a shark.

Kayakers also tend to be targets for Great Whites. Dan Prather, a Northern California man, was kayaking with friends in July when a shark went after his red boat. He escaped unharmed, but he's got jaw marks on his kayak. Prather declined requests for an interview.

AVOIDING SHARKS

Experts say the best defense against sharks is to learn how they behave and try to avoid them. That starts by staying out of the water in areas with large shark populations, especially at twilight or after dark. Sharks are not nocturnal, but they do often feed at dusk, and they have a competitive sensory advantage after dark.

The International Shark Attack File suggests watching for diving birds or jumping fish, and to avoid swimming in waters that are used heavily by sport and commercial fishermen. Similarly, be aware if you are playing in the water near sandbars or steep drop-offs, where sharks often prowl.

Don't get in the water if you're bleeding or menstruating, because it is true that sharks have an acute sense of smell when it comes to blood. Similarly, try not to wear shiny jewelry, which can look like the sheen of fish scales in reflected light, and avoid bright colors in murky water, because sharks see contrast particularly well.

GLEN JUSTICEMany instituitions cater to the widespread fascination with sharks. At the Aquarium of the Bay in San Francisco, visitors can enter a glass tube where sharks swim around. The facility even rents the space for childrens sleepover birthday parties.

While the best strategy if you see a shark is always going to be to exit the water calmly if you can, the Reefquest Center for Shark Research at the University of British Columbia suggests that, if you cannot exit the water, it may be advantageous to let a shark know you are aware of them. Sharks are ambush predators, meaning like prefer striking without warning.

Remember to take comfort in the statistics–and realized that sharks are in more danger than humans in most cases.

Estimating the world shark population is not an easy business, because they tend to range over great stretches of ocean and are not easily tagged. Scientists at Dalhousie University in Halifax, Nova Scotia, released a report last year showing massive declines in the world's population of deep ocean sharks, including Great Whites and hammerheads, and that North Atlantic sharks seem to be at the biggest risk.

Burgess said sharks have few natural enemies and none larger than man, who kills 40 to 50 million sharks each year through overhunting and other encroachment.

"Compare that to the four or five people killed by sharks worldwide," Burgess said. "I'd say the sharks are under attack, not the people."