How much of a danger are sharks? Depends

July 17, 2010|By TERRY TOMALIN / St. Petersburg Times

ST. PETERSBURG, Fla. - About this time each year, a fisherman catches a large, pregnant bull shark somewhere in the Tampa Bay area.

The angler usually drags the shark ashore and poses, jaws agape, for the obligatory dead-fish picture.

Then the phone rings.

"Is it still safe to swim?" a caller asks.

"Of course not," I respond. "But don't drive, either. You could get killed."

After a long, uncomfortable pause, I laugh and explain that a person is more likely to be killed doing home improvements than by a shark.

But nobody ever made a movie about the inherent dangers of house painting. However, let a great white shark loose off a New England shoreline on a summer's day and you've got blockbuster, a horror movie that will withstand the test of time.


One hundred million years ago, when dinosaurs ruled Earth, sharks dominated the ocean. Today, while highways and office buildings cover much of the planet's land now, all that remains of those "terrible lizards" are bones and fossils.

But sharks, nature's perfect predators, still swim supreme in the sea. Perched atop the food chain, they feed on the weak and the sick, which helps maintain nature's balance.

Slow to grow and giving birth to only a few pups at a time, a shark's only enemies are other sharks and humans. Sensitive to overfishing, many marine biologists fear that if too many sharks are caught and killed, entire species may disappear forever.

And thanks to the movie "Jaws," sharks in general have a bad reputation that may hasten their demise.

Most people are scared of sharks. But the truth is, most sharks are just as scared of humans. Of the 350 species of sharks, only a few are known to be dangerous to humans.

Most shark attacks occur close to land. Marine biologists believe that in most cases, the shark has mistaken the swimmer or surfer for a common food source, such as a seal or large fish.

But sharks are wild animals, and all wild animals should be treated with caution and respect. Almost any large shark, 6 feet or longer, can be considered a potential threat to humans.

Three species -- the white shark (Carcharodon carcharias), the tiger shark (Galeocerdo cuvieri) and the bull shark (Carcharhinus leucas) -- are responsible for most attacks.

"People have this impression that if a shark sees you that it wants to attack," said Brent Winner, a shark expert with the Florida Fish and Wildlife Conservation Commission's Fish and Wildlife Research Institute in St. Petersburg. "But that is a myth. If you look at the records, most attacks are bite-and-release."

Most attacks in Florida involve surfers in Volusia and Brevard counties.

"Surfers are in the water longer than swimmers," Winner said. "The longer you spend in the water the more likely you are to run into a shark."

Four near Florida shores:


The great hammerhead, which can reach lengths of 20 feet and more than 1,200 pounds, is feared as a man-eater, but in reality, this odd-looking fish is more interested in eating stingrays. Hammerheads are often found with stingray barbs sticking out of their mouths. One unfortunate specimen had been stung 50 times.


The tiger, along with the great white and bull, is one of the world's most dangerous carnivores. Reaching lengths of 17 feet, the tiger is an opportunistic feeder. This shark gets its name from the dark stripes that cover its body early in life but disappear as it grows older. A favorite food is sea turtle, which the tigers crush with their thick, jagged teeth.

Black tip

One of the most common inshore species of sharks, the black tip is so named because of the easily recognizable black markings on the ends of its fins. A fish-eater that feeds close to piers and beaches, black tips often swim near bathers without incident.


Possibly the most dangerous shark, the bull can live for long periods in freshwater. It has been found in the upper Amazon, 2,300 miles from the open sea, and in landlocked bodies of water, such as Lake Nicaragua. Bulls like shallow water and have been implicated in a number of unprovoked attacks, including several in the Tampa Bay area.

By the numbers:

1 in 11.5 million

Odds of a shark attack on a human

0 in 264.1 million

Odds of a fatal shark attack on a human


Number of reported shark attacks between 1956 and 2008 in Volusia County, Fla., making it the shark-attack capital of the world

Play it safe:

Although your chances of being killed by a bull shark are less than your chances of being struck by lightning, you can take some steps to protect yourself. Here are a few tips, courtesy of the International Shark Attack File in Gainesville, Fla.:

o Avoid swimming near the mouths of rivers or bays, areas favored by bull sharks.

o Do not swim near schools of baitfish. Bull sharks may be nearby.

o When spearfishing, be ready to drop your catch. Bull sharks are attracted by speared fish.

o Avoid swimming at night or early in the morning, when sharks are most active.

Worst-case scenario:

A University of Florida study showed that shark attacks on humans are more likely to occur:

o On a Sunday (more people go to the beach on that day of the week, of course)

o In water less than 6 feet deep (that's typically the depth swimmers favor at the beach)

o Between dusk and dawn (feeding time)

o During a new moon (tides influence bait)

o To those wearing black-and-white bathing suits (researchers believe the contrast is a factor)

Source: The International Shark Attack File; odds are from Year 2000 USA Beach and Injuries Fatalities report

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