Sharks Put the Bite on Humans in Coast Encounters

Out of the dark water below, a gaping circle lined with triangular two-inch teeth rises with blinding speed and clamps onto the unwary diver’s leg.

And, just as suddenly, the terrifying incident is over: The shark lets go and swims away, leaving its victim to struggle to shore.

As surfing, sail boarding and diving multiply the number of humans splashing in the water along the U.S. coasts, such attacks are increasing--this year, particularly on the East Coast.

“The water does not belong to human beings,” says George Burgess of the University of Florida, who keeps the national shark attack count. “When you’re entering the ocean, you’re entering the wilderness. It’s not jumping in your pool in the backyard.”

But the attacks still puzzle marine biologists, who are trying to determine why sharks strike--and why they don’t.

In 1995, according to Burgess’ numbers, virtually all of the attacks have occurred on the East Coast. Florida has had the most, with 28 incidents as of early October, compared to 22 for all of 1994. Three- or 4-foot black-tipped sharks are suspected in most of those attacks.

The Carolinas have recorded eight shark strikes, with Georgia and Texas each reporting one so far.

The West Coast lists three shark encounters, all in California and all believed to be great whites, the species demonized by the “Jaws” movies. In Hawaii, where tiger sharks are the usual culprits, a swimmer was killed last year, but the state has had only one attack in 1995.

No fatalities have been recorded in the United States this year. In fact, says Bob Lea of the California Department of Fish and Game Department, fewer than 10 confirmed shark attack deaths have been logged since the 1950s, when reliable statistics began to be kept.

“Jaws” aside, fatalities are rare--most are hit-and-swim encounters, with the shark almost as eager to get away as its human prey.

“The sharks get an immediate understanding that they have bitten off more than they can chew--literally,” Burgess says.

Marco Flagg, an experienced diver attacked at Point Lobos in Northern California in June, can attest to that. He sports the scars of a three-inch gash in his arm and a V-shaped puncture on his leg--30 inches apart, and from the same bite.

“I looked to my left and below and saw the massive, wide open, near-circular, teeth-lined mouth coming right at me,” Flagg says.

His air tank and an underwater computer absorbed most of the blow; after one chomp, the shark disappeared.

Marine biologists aren’t sure why sharks attack in the first place, much less why they let go.

One of the nation’s leading experts, Samuel “Sonny” Gruber of the University of Miami, estimates attacks are up about 20% this year. He thinks the increase in East Coast incidents can be blamed on the unrelenting series of tropical storms and hurricanes. That makes better wind and surf conditions and puts more people in the water near the offshore sandbars where fish--and sharks--collect.

“There’s also more turbulence in the water,” he says, “so your white hand or foot can look like a fish.”

In all three California attacks, the victims were on or near equipment such as boats, sail boards or water scooters. Some scientists believe the sea hunters mistake the oval shapes for their favorite food--seals and sea lions.

But not everyone agrees.

“We’ve seen them attack a 12-foot sail board,” Lea says. “That isn’t going to resemble a marine mammal. We think that case was territorial.”

Sharks also have repeatedly bitten small boats unlikely to be confused with a sea lion.

Peter Klimley, a shark researcher at Bodega Marine Laboratory north of San Francisco, thinks sharks simply have a bite-first, ask-questions-later attitude.

Territoriality, mistaken identity or a bite-everything feeding strategy may explain why the sharks clamp down in the first place. But why don’t they finish off their human meals once they’ve attacked?

Gruber says sharks may just prefer the odor and taste of seafood.

Klimley, however, has come up with an intriguing theory: People might not be fat enough.

“Fat has twice the energy value that muscle does. Seals and sea lions have a layer of fat, unlike birds, humans and sea otters,” he says. “Sea otters often wash up with tooth fragments in them, but we never find them in the stomach of a shark.”

By selectively hunting fatty animals that give more bang for the bite, the shark optimizes its own use of energy, especially in cold waters.

In videotapes of sharks scavenging on a dead whale, Klimley says, they clearly concentrate on the fat tissue, ignoring the rest of the animal.

In trying to get sharks to ingest transmitters, Klimley found they eagerly swallowed them when inserted into dead seals donated to the laboratory. But when he ran short of seals and tried to use sheep carcasses, the sharks just weren’t interested.

Off the coast of Canada, researchers found 500 dead seals that had been stripped only of their layer of fat.

Along with supplying yet another good reason to diet, the theory should be reassuring to swimmers and surfers. If true, it’s unlikely a victim will be eaten, and waiting until the shark lets go appears to be the best strategy.

But be careful, says Burgess, and look at your activities from the shark’s point of view:

“He’s out there working--we’re just playing.”