A the Sea Shepherd Australia/ Animal Amnesty photo shows a tiger shark being caught off Moses Rock in Western Australia, February 22, 2014

More than 170 sharks were caught during a controversial cull policy in Western Australia following a spate of fatal attacks, figures showed Wednesday, with 50 of the biggest ones destroyed.

The , in place around popular west coast beaches, was given the green light in January after six fatal attacks in the past two years, angering conservationists who claim it flies in the face of international obligations to protect the .

The state government said the aim was to reduce the risks to water users. Baited drum lines with hooks were set one kilometre (0.62 miles) offshore at the busiest beaches for a trial period from January 25 until April 30.

Any shark longer than three metres (10 feet) snagged by the lines and deemed to be a threat—including great white, bull and —could be killed.

The data released Wednesday showed that 172 sharks were caught with 50 of the biggest ones, including one of 4.5 metres, destroyed. Ninety were tagged before being released.

WA Fisheries Minister Ken Baston called the mitigation policy a success, saying it had restored confidence among beachgoers and contributed to knowledge about shark behaviour.

"The human toll from in recent years has been too high," he said.

"Our carefully implemented policy targeted the most dangerous shark species known to be in our waters—white, tiger and bull sharks.

"While of course we will never know if any of the sharks caught would have harmed a person, this government will always place greatest value on human life."

The state government has applied to federal authorities to continue the programme for three more years. But the state Labor opposition claimed no scientific evidence had been produced to show the policy was working.

"What people want is scientific research to show why the government thinks this policy makes our beaches safer," Labor fisheries spokesman Dave Kelly told ABC radio.

"None of that has been provided and the other thing that the should be releasing is how much money this policy is costing."

Sharks are common in Australian waters, and experts say attacks are increasing in line with population growth and the popularity of water sports.