A tourist trade for people to watch sharks underwater using bait to attract them is blamed for a rise in attacks along the 300km of coast around Cape Town.
In the past four years, 13 have been recorded, three of them fatal. In the previous 42 years there were 17, one fatal.
Nearly all the attacks are thought to have been by great whites. In two recent fatalities — a woman swimmer and a spear fisherman — the bodies were never recovered.
The tourists wear wetsuits and get into a cage tied to a boat with the lid above water. The operators throw bait in the water. The tourists hold their breath and duck underwater to see the sharks swim past.
Of the 12 cage-dive operators in South Africa, eight are in Gansbaai, south-east of False Bay on the Western Cape coast.
Marine biologist Michael Scholl is a guide on a cage boat called Shark Fever and does research on great whites.
Mr Scholl has used dorsal fin markings to identify 1200 great whites since 1998 in and around Dyer Island, a habitat for seals which are prey for the sharks.
The Western Cape coast was a prime habitat for sharks but it was difficult to estimate the population, he said.
On a recent trip with 15 tourists, he and his research assistants spotted 10 different, 3m to 4m great whites within 1.5km of shore in three hours.
Three or four times a shark got the bait before it could be pulled from the water. Sharks lunged out of the water showing razor-sharp teeth, or rattled the cage while thrashing for the bait.
Mr Scholl said he was trying to change the Jaws film image through an hour briefing before every trip. Responsible cage diving helped research and could demystify great whites.
“The more people see those white sharks out there for what they are, the less people will be afraid of sharks,” he said. “That’s why I’m supporting it. I think it’s a great tool for education.” Only a few people a year were killed by sharks worldwide. “More people have died today in this country from AIDS, many more. Yet sharks make the news,” he said.