In a life-and-death struggle, Australian surfer Jake Heron punched the great white shark as it bit his arm and thigh, turning the ocean into a bloody cauldron.

Miraculously, Heron, 40, lived to tell the tale.

Very few people survive an attack by a great white, which can grow to 20 feet (six metres), weigh 2.5 tonnes, and with enough power in its jaws to lift a car.

Two weeks earlier, marine biologist Jarrod Stehbens, 23, also fought a great white as it pulled him underwater as he tried to climb into a boat. Sadly, Stehbens lost his fight for life.

These two attacks in the past few weeks, both in waters off South Australia state, have sparked an emotional debate in Australia over whether the great white, the ocean's fiercest predator, should be culled.

Displaying his savaged surfboard, bitten in half by the shark, Heron is adamant that Australia should end its protection of the great white and start culling.

"They're top of the food chain and nothing affects it," Heron said after his attack.

"It's time they started controlling the numbers. Controlled culling - they kill our national emblem, the kangaroo, they kill elephants in Africa," he said.

"The numbers have gone up and there's too many of them," he said.

But the parents of Stehbens, who fought in vain to free his leg from the shark's jaws after being attacked while diving for cuttlefish, reject calls to kill the shark.

Australia has a global reputation for sharks, with its cold southern waters the ideal breeding ground for great white pointers. But the chances of an attack are slim. In fact, swimmers are more likely to drown than be bitten by a shark.

In the past 50 years, 60 people have died after being attacked by a shark, an annual average of 1.2 fatal attacks. This compares with two to three deaths each year from bee stings and the drowning of hundreds of beach swimmers and fishermen.

Too bony

"Shark attacks are very prominent in the media when they occur, but they are rare events," said Barry Bruce, a government marine scientist who has studied great whites since 1987.

Great whites are "hot-spot hunters," which target oceanic biological activity, like big schools of fish, seal colonies and dead whales. The sharks do not intentionally hunt humans.

"We are not seeing a trend of increasing shark attacks against a trend of increasing population," said John West, who runs The Australian Shark Attack File.

The odds of a shark attack are 15-20 million to one, he said.

"Unfortunately, they test to see if you are edible, but they can only use their teeth or nose and in doing so they do a lot of damage to soft, squishy humans," said West.

Humans are not sharks' ideal prey because we are bony and have less flesh than seals or dolphins but unfortunately one exploratory bite by a great white, which has poor eyesight, is enough to kill most humans.

According to reports of attacks, very few great whites return for another bite. Australia regards the great white as an endangered species and has protected it for the past 10 years. Great whites are also protected by South Africa, Namibia, the Maldives and by the US states of Florida and California.

Scientists say there is no evidence that shark numbers have increased dramatically as a result of protection, as counting is impossible, and sharks have slow reproductive cycles.

Scientists say culling would have little impact on attacks and would upset the food chain by removing an apex predator.

Those calling for culling also claim that shark tourism and tuna farming has attracted sharks closer to shore and swimmers.

Again, scientists discount such an argument, saying shark tourism occurs well offshore. It involves operators dumping bloody fish bait into the ocean to attract sharks and then lower tourists in cages into the water.

Hunting highway

Culling sharks would be very difficult and costly, scientists say, particularly as great whites travel thousands of kilometres each year along "hunting highways."

Great whites patrol an area that extends from Australia's cold southern waters to its tropical northern waters on both its east and west coasts. Usually they move north during autumn and winter and south in spring and summer.

Scientists believe that, if there is any increasing risk of shark attack in Australia, it will be caused by people, not sharks, as more leisure time means more people are entering the ocean.

Source: China Daily