Hawaiian scientists put a tail on tiger sharks : A study finds they travel far, so trying to hunt down the few that attack humans may be futile.

Don Bloom was taking leisurely strokes 100 yards off the coast of Maui’s Wailea Resort at midday when he felt a sharp pain in his side and whirled around to confront a large tiger shark.

“I kicked it with my heels as hard as I could, with both feet, and it dove under,” he said later. The 38-year-old fitness swimmer headed for shore, bleeding from four puncture wounds. He had been swimming that stretch for years and had never even seen a shark. “Sharks were the last thing on my mind,” he says.

The June 13 attack was the first reported this year in Hawaiian waters. Three years ago a spate of shark attacks, two of them fatal, prompted panic and widespread shark hunting here.

Spurred in part by public concern, researchers at the Hawaii Institute of Marine Biology at the University of Hawaii are making the first systematic effort ever to study what makes tiger sharks tick--and occasionally bite humans.

The initial results of their tracking study, using sonic transmitters implanted in sharks’ bellies, appear to buck conventional wisdom. Common folklore holds that tiger sharks patrol a small coastal “back yard,” much as a dog would. Instead, the researchers are finding, tiger sharks travel great distances, even inter-island, and plunge as deep as 1,000 feet, the deepest ever recorded for the species.

Tracking a shark from just offshore of Honolulu International Airport, “at the end of 48 hours, we’ve been 38 miles offshore,” said research associate Kim Holland, who is heading the study.

The research suggests that efforts to cull “rogue sharks” after attacks may be pointless. The chances of catching the shark responsible are slim, and any sharks removed may be replaced by others from elsewhere.

Although tiger sharks have roamed the ocean since before the time of dinosaurs, scientists know little about them. Averaging 10 to 14 feet long, they do poorly in captivity, and human encounters with them in the wild can be dramatically brief.

In any case, such meetings are rare. Despite their fearsome reputation, tiger sharks rarely approach humans. The reverse is also true. Before the current effort began, only one tiger shark had ever been tracked, near an unpopulated atoll in the northwestern Hawaiian islands.

So far, the university team has tracked eight tiger sharks, for as long as two days, a painstaking and exhausting exercise.

“It’s not dangerous, it’s just bloody uncomfortable,” said Holland on a recent ocean foray. “The more we do this, the more secure I personally feel about being in the water. You have to strike a balance between being awe-struck and not being too casual about it.”

The research team lays fishing lines, baited with tuna heads, a mile offshore from Honolulu International Airport’s reef runway. Once the researchers hook a tiger shark, they pull it alongside the boat and flip it on its back in the water, a position that sends the shark into a trance. In the space of eight minutes or so, they make an incision in its belly, slip in a transmitter and stitch up the wound. Then they let the shark go, and the chase is on.

Using telemetry techniques honed on research with tuna and turtles, the team follows the shark in a small boat for as long as their fuel supply and their own stamina will let them. Of the eight sharks tracked, three traveled straight to Penguin Banks, off Molokai. One headed due south for 30 hours. The others headed off shore but were lost within hours.

The researchers also are tagging and releasing animals using conventional ID tags. Eight of 28 animals tagged were recaptured nearby, from a few weeks to six months later. The high recapture rate and the tracking results suggest that if sharks patrol, it is on a grand scale.

“Our preliminary analysis at this point is that there is a degree of fidelity to a certain site,” Holland said, “but there is a lot of distance traveled between.”

Holland dismisses some observers’ questions about whether the research itself--from the hooking to the surgery--affects the sharks’ behavior.

“In the course of their daily lives, they get into some severe tussles,” he said. “ . . . We find stingray barbs embedded in their faces. That’s one of their favorite foods.”

In an effort to monitor the animals’ movements on a more random, natural basis, the research team also plans to put listening devices on the ocean floor. Each transmitter implanted in a shark has its own signature, and the device would record its movements.

Holland and his crew believe there is far more to learn than there is to fear from tiger sharks. Scientists hope the sharks’ vigorous immune systems--they rarely fall ill--may hold keys to fighting diseases like cancer and AIDS.

Last year, two people were bitten by sharks off Hawaii. The year before, three surfers were bitten and one was knocked off his board. All survived.

“When you think how many thousands of people there are in the water every day, 365 days a year, that’s really quite incredible,” Holland said. “These animals aren’t just biting anything that is the right size in the right place. If they were, we would have dozens of attacks a week. They must be very, very conservative in what they do.”

Two days after his shark bite, Bloom forced himself back into the water. “I was jumping at every shadow,” he said. But he feels more confident these days. He swims only in clear water now, and keeps an eye out.