Sharks Make For A Dangerous Game Of Tag

May 31, 2009

Release from: Susan Cocking
Miami Herald

WEST END, Grand Bahama Island - There are a couple of ways to implant a tag in a 9 ½-foot-long tiger shark -- neither of them easy and both fairly dangerous.

You could hook the animal on a baited longline, drag it onto your boat and insert the tag -- all the while trying to avoid multiple rows of teeth.

Or, you could do it like the crew of researchers on the Gulfstream Eagle did a couple of weeks ago -- lasso it underwater, tire it quickly with those big floating polyballs like in the movie Jaws and sew in the tag with the shark in the water, and still manage to avoid said teeth.

''A little disorganized -- but it worked,'' renowned marine artist and scientist Guy Harvey said after the shark swam away.

Harvey and his group of friends and colleagues had chartered the Riviera Beach liveaboard dive boat for five days to study the sharks that appear on Tiger Beach -- a sandy shoal about 20 miles north of here, on the Little Bahama Bank.

The area got its nickname about five years ago, when the crews of visiting dive boats observed as many as seven animals up to 14 feet long cruising the clear shallows.

CHUM HELPS

To draw the tigers in for closer inspection, the crew of the Gulfstream Eagle put perforated tubes filled with chum in the water and tossed hunks of bonito and barracuda overboard. The bait and chum enabled divers to shoot close-up video and photographs and set the stage for a bizarre, but successful, underwater capture.

Harvey spent hours in the water swimming with and videotaping up to 12 tiger sharks during the five-day trip -- always with chum in the water. Neither he nor any of the guest divers or boat crew members sustained as much as a scratch from their quarry, nor from the numerous smaller lemon sharks that also hung around. A couple of times, Harvey and the other videographers had to thrust their cameras at sharks that bumped the lenses, but that was about as violent as things got.

''It's much more controlled than I imagined,'' said Harvey, who previously has jumped in the water with assorted sharks and billfish to shoot video for his popular television shows and artwork. ``You'd never get this close to them without chum. If you don't use food, it's not going to happen.''

Besides getting close enough to inspect the tigers' dental work, the divers had a scientific mission: to insert an acoustic transmitter tag in one of the animals. The tag emits a signature beep that is picked up by an underwater receiver in the area. Whenever the tagged shark passes within 300 to 500 meters of the receiver, it stores the signal to be downloaded later onto a computer. As far as anyone knew, the lone receiver in the area was installed by prominent University of Miami shark scientist Samuel ''Doc'' Gruber.

TRACKING TIGERS

Harvey said the trip was a pilot study to try to track the movements of the tiger sharks that frequent the area. Long-lived, slow-growing and late maturing, tiger sharks are an important part of the marine ecosystem -- feeding on sick and injured fish, sea turtles and other animals -- to keep the environment in balance. Long feared as mindless man-eaters, tiger sharks do not have the same domestic and international protections from overfishing that great whites and several other large shark species have.

''We should tag every one of these animals to see where they go,'' Harvey said. ``The ultimate would be to have the species protected or -- if not -- this area of the Bahama Bank could be [designated] no shark fishing. This is the beginning of what will hopefully be a 20-year study where we involve the Bahamian government, researchers from various institutions [and] dive operators.''

TRICKY TASK

But the first step was to put a tag in a shark. Michael Domeier, president of the Marine Conservation Science Institute based in Fallbrook, Calif., had brought a homemade shark-capturing device that looked something like a barbless, King Neptune-style pitchfork. It consists of an aluminum collar attached to a stainless-steel pole that the user clamps over the shark's body forward of the tail.

''It allows me to capture the sharks without using a big hook,'' Domeier said.

But the device had some inherent problems: the collar was too wide for the size of the tiger sharks in the area and it was difficult to wield underwater. Repeated attempts to capture a 9 ½-foot female that swam up to the stern dive platform of the Gulfstream Eagle to eat a chunk of bait were unsuccessful.

Domeier then modified the device using come-along straps inside the collar to limit its radius. Captain Rob MacDonald, a veteran shark diver, took it underwater -- after first removing the pole-handle -- and scored several near-misses with the same female shark.

MacDonald's colleague, cocaptain John Rose, was growing impatient with the repeated failures.

''I think I've got a good way to do this -- if they let me do it,'' he muttered.

MAKING ADJUSTMENTS

Rose created an old-fashioned lasso out of a length of rope and a carabiner and dived underwater. When the often-encountered tiger shark swam close enough, Rose boldly held out a chunk of dead fish. The shark tipped down to eat it and Rose slipped around behind her, encircling her with the lasso and clipping it tight.

SHARK WRESTLING

A rodeo bronco has nothing on a lassoed 9 ½-foot tiger shark. The animal bucked, swam to the surface, dived to the bottom and bent its muscular body nearly double -- teeth bared -- trying to bite off the pesky line holding its tail.

Rose held the end of the line which, fortunately, had been attached to a giant floating polyball. As he wrangled the shark, Domeier -- along with shark scientists Mahmood Shivji and Benjamin Victor, cinematographer Rick Westphal and Gulfstream crew member Tom Williams -- jumped into a motorized dinghy and took the line. They attached a second polyball, which prevented the shark from sounding or swimming too far away.

After a few minutes, the shark surfaced and they shortened the line, then motored slowly back to the stern of the Gulfstream Eagle. A second line was used to lasso the shark by the head, and the dinghy got out of the way so the scientists could work from the dive platform.

The shark struggled and splashed against the lines.

''Get everyone on that rope and pull!'' commanded a usually soft-spoken Shivji, director of the Guy Harvey Research Institute at Nova Southeastern University.

One of the scientists deftly flipped the shark over on its back to cause tonic immobility -- a tranquilized state that occurs when the shark is disoriented -- as everyone held fast to the lines.

Then Victor, whose real job is a pathologist in California, made an incision in the belly, inserted a transmitter the size of a forefinger and added a suture to make sure the tag didn't pop out. The whole process -- from initial wrangling to the conclusion of surgery -- probably took about 20 minutes. Then the shark was flipped upright, the ropes removed and it swam away smartly.

The entire crew cheered and exchanged high-fives.

''It acted [ticked] off,'' Domeier said of the shark's exiting demeanor.

After that, the only thing left to do was to listen for the sound of the beep.