Sydney  - Australian marine biologist Scoresby Shepherd thinks an increase in attacks could signify that sharks are starting to see humans as food because tuna are getting scarce.

"It's a well known biological phenomenon, which is called prey switching," Shepherd said.

The numbers of attacks are rising and during the past 34 years sharks have killed 32 people in Australia.

But turn the tables and it's clear that sharks have the most to fear. Around 100 million sharks a year are killed around the world. It's a rate well above replacement level. They die mostly for their fins, which are a delicacy in some Asian countries.

Sharks are adults before they breed and don't have many young. They are rarely a primary catch. The fishing boats their fins end up on are hunting for rays and other more valuable species. They get caught on the hooks, and often their fins are sliced off and the sharks left to a painful, lingering death in the ocean.

Every year Australia exports more than 500 tons of shark fins, shark liver oil, shark cartilage oil.

"We risk going down in the history books as the generation that let sharks go extinct because of an insatiable market for shark products," said Ghislaine Llewellyn, a consultant to conversation organization WWF. "Sharks play a crucial role in the balance and health of marine ecosystems and are especially vulnerable to overfishing."

Llewellyn is pushing for parts of the Pacific Ocean like the Great Barrier Reef and the Coral Sea to become shark sanctuaries. At the moment, she said, "Australia continues to be part of the problem and not part of the solution." (dpa)