The first shark glides by not long after the boat drops anchor. It is a small one, as great whites go, between six and nine feet long, a slinking gray shadow in this aqua-blue water a half mile from shore. It circles around the 32-foot catamaran, smelling the "chum slick" – water with dissolved tuna bits – that Michael Scholl has been pumping into the ocean from a big barrel.
"Shark!" one woman cries, and the other tourists rush starboard, vying for a better look. Soon, they will slip into wet suits and goggles and get an even closer view, sliding into a metal cage suspended in the ocean water, cold even now in the Southern Hemisphere summer.
Mr. Scholl smiles at the excitement. Sharks are his passion, so he's happy when tourists start buzzing at the sight of a telltale dorsal fin, the gray triangle that pierces the water's surface.
South Africa's rapidly growing shark-cage industry baits adrenaline addicts with promises of "Jaws"-like encounters, and Scholl knows that many of the people on his boat are simply here for the thrill. But he hopes to turn them into shark lovers, by sharing his research and his belief that great whites are the "most fascinating, beautiful, and perfectly adapted animals out there."
This puts him at the epicenter of the debate here about great whites and cage diving – about safety, shark conservation, and animal exploitation. He works in an industry that has been criticized by environmentalists for perpetuating "Jaws"-like stereotypes, but he is a researcher and conservationist first. His findings have helped the cage-diving business expand, but he knows they may eventually lead to more restrictions. But in the end, he says, he's squarely on the sharks' side.
"I've always been supportive of the cage-diving industry as long as it's done properly," Scholl says. "The more people see those white sharks out there for what they are, the less people will be afraid of sharks.... I think it's a great tool for education."
On one sunny morning, Scholl clicks through a computerized slide show in the headquarters of Marine Dynamics, the company that employs him as a shark guide. This is his pretrip presentation, with details about great white biology, South Africa's unique ocean system, and his research.
For eight years, Scholl has been building what shark experts say is the world's most extensive database of great whites, using the individual marks and notches on dorsal fins as identifiers.
This is the main reason he works for the cage- diving company – he needs a way to get out on the water to continue this project. He and other scientists hope that this research will help them estimate the shark population and learn more about great white behavior.
Scholl's work is "vital," says Michael Meyer, of South Africa's Marine and Coastal Management. "He's got the biggest database as far as known sharks. We give whatever we collect to [Scholl]."
The Convention on International Trade in Endangered Species prohibits the sale of great white jaws – long considered a prized hunting trophy – and the World Conservation Union has great whites on its "red list" of threatened species. But nobody knows exactly how many great whites still exist. Nobody has seen a great white mate or give birth. Researchers don't understand why the sharks linger in one part of the ocean for a week and then move elsewhere.
"There is a fascination with sharks, sure," says Dylan Suhor, a research assistant who is working with Scholl. "But when you say 'shark,' people think 'Jaws.' There are many more questions than answers."
Mr. Meyer says there are only about half a dozen scientists working to answer these questions along the southern coast of Africa – one of the world's prime great-white-spotting places. These sharks don't survive in captivity, so they're notoriously difficult to research.
Aboard "Shark Fever," Scholl records information about the sharks he sees swim by. "I like the fact we haven't been able to successfully cage every single [kind of] animal on this planet," he says. "It's kind of nice to know there are some animals that are going to refuse that."
Meanwhile, tourists aboard are lining up for their own cage, to be lowered into the sharks' world. The boat has been chumming, letting out tuna-water mix, for an hour. It has attracted the sharks' attention, and one at a time, they circle the boat, looking for a meal. They zigzag under water, trying to find the source of the smell. To get a shark to come to the surface, crewmembers toss out a fish head on a float tied to a piece of rope. The sharks lunge toward this bait, sometimes splashing out of the water, swimming inches away from the 3- by 6-foot steel cage, all but the top foot of which is submerged in the rocking, aqua water.
The captain tells four or five tourists huddled in the cage when to hold their breath and duck under water in order to see a shark – and sometimes its teeth – up close and personal. Sometimes the shark lunges, a powerful surge of gray flesh bursting through the water, its mouth agape, displaying rows of jagged, sharp teeth. Sometimes it glides by, ghostlike, large, dark blue eyes inches from human eyes wide behind goggles.
The tourists involuntarily pull back. Often they come up for air, gasping and exclaiming.
The crew tries to make sure the shark doesn't actually get the fish bait. This is a regulation established in part to address the concerns of surfers and other water sports enthusiasts who have criticized shark diving for causing more shark-human conflict in waters near Cape Town. (There were 30 shark attacks on humans between 1960 and 2006, according to government data. Thirteen of these, including three fatal attacks, were in the past four years.)
But Scholl says a more probable reason for the attacks is increasing numbers of people in the water, due in part to better wet suits. He says that the sharks only stay in the waters near Gansbaai for a few weeks. And, because the cage-diving crew typically pulls bait away before sharks ever even get a taste of it, he explains,"I don't think the shark is going to distinguish the boat from the cage from the people inside.... Even if the shark goes to the beach five minutes later and sees a surfer or swimmer, I don't think he's going to go, 'Wait, that's what was just in that cage.' "
This view is shared by a recent World Wildlife Federation report that found no scientific link between cage diving and the attacks.
A better reason for keeping the bait away from sharks, Scholl says, is that it isn't environmentally sound to feed wild animals.
Scholl, a native of Switzerland, moved to South Africa for the sharks in 1998. At first he funded his research with grants, but moved to the shark-diving boats when those funds ran out. His work helped expand the industry when he discovered a new area where sharks congregate – now dubbed Shark Bay – that let companies ensure sightings for their tourists.
But Scholl now suspects that Shark Bay might be a great white mating ground – something never before identified by humans. He thinks this, not the hunting in a nearby seal colony, might be why the sharks are here. If he can prove this theory, it would be a boon to shark research, and conservationists, including Scholl, would clamor to stop tourist activities there.
He says he isn't well liked in the business because he has pushed for government regulation of the diving and files official complaints against operators who he believes mistreat sharks. He says some operators manipulate bait so that sharks lunge for it and slam against the cage – a thrill for tourists but harmful to the sharks.
But Scholl shrugs off the criticism.
"The sharks come first," he says. "For me, it's always been about the sharks."
• Read the reporter's first-person account of going eye to eye with a great white shark at http://weblogs.csmonitor.com/notebook_africa