Thousands of people have gathered on beaches under banners demanding Australia's government 'Save Our Sharks' and stop a planned cull, which activists says will damage the ocean's delicate ecosystem.

Western Australia's government will install 72 hooks with bait, close to Perth's beaches, to kill the sharks, whow have been responsible for seven fatal attacks on swimmers in just three years. The policy will begin on January 10th.

Any shark which is more than three metres long, which might include Great White Sharks, will be shot and killed by commercial fishermen, given the contracts for the cull.

West Australians for Shark Conservation founder Ross Weir told those present at the rally that the drum lines attached to the baited hooks could harm animals like dolphins, turtles and fish, according to a report by local newspaper, the West Australian.

More than 4,000 people gathered for a demonstration at Perth's Cottesloe beach, the BBC reported, quoting one protester as saying: "Without the sharks there will be no future for humanity because they balance out the ecosystem and every living creature in the sea is really important."

Other protests have been held in Melbourne, and more are planned for the coming month.

The region's acting premier said it was wrong to call it a cull, saying it was focused only on areas where the public could be in danger.

"If it were a cull we would be out catching sharks the length and breadth of the state," he said.

A petition opposing the cull now has over 36,000 signatures.