The controversial catch and kill policy was introduced as a trial this year around popular west coast beaches following a spate of fatal attacks.



More than 170 sharks, mostly tiger sharks, were caught during the 13-week summer season, with 50 of the biggest ones destroyed.



The state government has applied to national authorities to extend the policy, putting 72 baited hooks attached to floating drums one kilometre (around half a mile) off the busiest beaches between November and April until 2017.



The Environmental Protection Authority (EPA) is assessing the proposal, which has angered conservationists who say it flies in the face of international obligations to protect the great white shark.



The Australian Broadcasting Corporation said it had obtained a submission to the EPA from more than 250 of the world's leading marine biologists and researchers who said there was little science to back the policy.



They included US marine biologist Elliott Norse, who worked for several presidents and was a key force behind the scenes in President Barack Obama's recent push to preserve vast parts of the Pacific Ocean, ABC said.



"I think killing apex predatory sharks like tiger sharks is a terrible idea," he said.



"Apex predators (animals at the top of the food chain) are really important in ecosystems and when we kill them what we often find is really bad things happen."



Tiger sharks were not thought to be responsible for the six fatal attacks off Australia in the last two years, with great whites blamed. No great whites were caught in the trial.



Another scientist, Jessica Meeuwig, said Hawaii was an example of drum lines having no effect on safety.



"In Hawaii they spent 16 years killing tiger sharks through a hook and line programme very similar to what we're doing," she reportedly said in the submission that she coordinated.



"And it had no impact on the number of incidents with sharks."



The state government has said its policy -- which is based on the use of drum lines in Queensland, where there has been only one fatal attack at a beach using the baited hooks or nets since 1961 -- had restored confidence among beachgoers.



However, the ABC said Western Australia Fisheries Minister Ken Baston was unable to point to any studies about the efficacy of drum lines.



Submissions to the EPA are due to close on Monday.