Surfers and 'shark tourists' blamed for increase in attacks by great whites

Eco-tourists and surfers invading the natural space of great white sharks are directly responsible for the recent spate of attacks, a leading shark expert said yesterday.

George Burgess, director of the Program for Shark Research at the University of Florida, said: "As more people take part in aquatic pursuits they are bumping into sharks more. It's as simple as that. The number of shark attacks is rising year by year while the shark population is dwindling - it's not rocket science to see that something is provoking them. We are swamping the near-shore environment."

He was commenting on incidents in the past few weeks that have seen one Australian killed and two Britons attacked. One was surfing and the other was in a shark cage on a "see great whites" tour.

Dr Burgess had harsh words to say about the growing number of firms in South Africa, Australia and the United States offering "great white shark tours" by boat, or, for braver souls, in a cage lowered into the sea. These often strew bait, known as "chum", in the water to attract great whites. "When you feed a shark you are provoking him, so most shark attacks are not actually attacks, just responses to the environment," Dr Burgess said. "Throwing fish and blood into the sea is altering the way that sharks behave. Shark tourism is not seeing sharks in their natural habitat - what tourists are watching is a circus.

"A lot of what you see with cages is the white shark being fooled by the electrical field from the metal. These animals have very acute electro-magnetic sensitivity, particularly up close, as they use it to catch fish. The cage fools them."

Dr Ellen Pikitich, of the Pew Institute for Ocean Science, New York, agreed: "Putting a cage into an area where there are known to be great whites is irresponsible." In the past decade, both surfing and shark tourism have boomed. The same period has seen a big increase in unprovoked shark attacks, according to the International Shark Attack File. This deals with confirmed cases and excludes provoked attacks, such as when a diver grabs at a shark. In the 1950s, there were barely a dozen unprovoked attacks a year; by the 1980s there were about 20; and last year there were 61.

Very few conform to the popular image fostered by Jaws. A mere handful are on bathers entering or exiting the water; the vast majority are on swimmers and surfers. Forty years ago, attacks on swimmers were twice as common as those on surfers, but last year they were both around 40 per cent.

There is, as yet, no category for attacks on shark tourists, but there may soon have to be. Andrew McLeod, senior aquarist at the Deep Submarium in Hull, said: "The problem is that some tour operators are more scrupulous than others. The practice of tow-roping - baiting a rope and pulling it towards the boat for a better view of the shark - is incredibly irresponsible. It really angers them."

Although attacks on people have been made by 30 or so species of shark, most are attributed to tiger, bull and great whites, with the last most commonly blamed. Yet, surprisingly little is known of what, for all its power, is a creature that experts say combines inquisitiveness and nervousness in equal measure. Its mating and birth have never been observed, its migrations and living arrangements are largely conjecture, and estimates of its numbers mere guesswork.

There are two main theories on attacks by great whites. One is that the silhouette of a wet-suited surfer, strikingly similar to that of a seal when seen from below, leads the shark to mistake it for its favourite meal and attack. When the shark realises it is not the fatty taste it was expecting, it spits the swimmer (or bits of him or her) out.

The second theory is that the inquisitive great whites, which use their mouths much as we do our hands, take a bite to feel an unfamiliar shape. (They have been known to bite platforms, boats and buoys.)

Most shark attacks do not result in death, which is more than can be said for our attacks on them. Last year, seven people worldwide were killed by sharks. And the number of them killed by us? Around 50 million.