Sharks longer than 3 metres that get near popular beaches in Western Australia will be caught, shot and dumped back into the sea, in a series of measures aimed at reducing public anxiety over attacks.

Details of the WA government’s controversial “shark management” strategy have been released, with sharks bigger than 3 metres singled out for shooting and then discarding offshore.

A tender released by the government calls for an “experienced licensed commercial fishing organisation” to deploy and maintain up to 72 drum lines off popular beaches in Perth and elsewhere along the south-west coast.

The drum lines, containing a hook with bait on them, will catch and, eventually, kill passing sharks that come within 1km of the beach.

Should a live white shark, tiger shark or bull shark longer than 3 metres be found on the drum lines, they will be “humanely destroyed” with a firearm, according to the tender documents.

Shark corpses will be then tagged and taken further out to sea and dumped. Other animals caught on the baited hooks will be released alive “where possible”.

The drum lines will be patrolled by boats for 12 hours a day, seven days a week, until April. Only contractors’ vessels will be allowed within a 50-metre exclusion zone set up around the drum lines.

The state government said the tender was a “direct response” to the “unprecedented” number of shark attacks off the WA coast. Surfer Chris Boyd, 35, was killed following a shark attack in November, becoming the sixth swimmer or surfer to die from shark-inflicted injuries in the past two years.

Ken Baston, WA’s newly-installed fisheries minister, said that while the government had invested $5m on researching other deterrents, it was “committed to taking immediate steps” to reduce the threat posed by sharks.

But scientists and animal welfare groups have labelled the strategy barbaric and even counter-productive.

Christopher Neff, who has completed the first PhD on the “politics of shark attacks” at the University of Sydney, told Guardian Australia there was “no evidence” that baited drum lines reduced the risk of a shark bite.

“There is evidence that drum lines draw white sharks in, but I am unclear on how this is meant to reduce the risk to the public,” he said.

“If the point is to symbolically kill a protected species for political gain then it will be successful, but if the point is to protect the public from sharks this policy will likely be a failure.”

Neff said evidence from Queensland, which also used drum lines, albeit not baited like in WA, suggested the way people used beaches was more important in avoiding shark attacks, with swimming between the flags a “good shark bite prevention tool”.

“The answer is to tell the public the truth that shark bites, like lightning strikes, will not have a government solution,” he said. “This is not a problem of innovation, but of arithmetic.

“The assumption would need to be that all of the sharks that are attracted are caught in the drum lines. But this is not the case. In Hawaii when they set long lines to prevent shark bites for nearly 20 years they found that it had no effect on reducing the rate of shark bites.

“They have also done long lines in Recife, Brazil and this has had no effect on reducing shark bites.”

Beach goers in WA are now also able to get warnings on shark movements from Twitter.

Transmitters attached to more than 320 sharks, including great whites, monitor the creatures’ movements along the WA coast. Should any of these sharks move within 1km of a beach, an alert identifying the type of shark will be posted on the Surf Life Saving Western Australia’s Twitter account.

On Friday, sharks spotted included a 2.5-metre animal within 50 metres of the beach, as well as a bronze whaler shark near Garden Island.

Chris Peck, from SLSWA, told Guardian Australia the system was “not perfect” at preventing attacks but had proved effective in informing the public of potential risks.

“We can’t guarantee safety, but it’s about getting information to people to help them make decisions,” he said. “There’s no doubt the increased sightings and attacks are having an effect on people’s mindset. While people used to go to isolated beaches, they just go to patrolled areas and are not spending as long in the water.

“These are all responsible actions, but the drowning statistics are tenfold that of shark attacks. There’s definitely a demonisation of sharks. There’s a hysteria about them in the media that can be hard to temper down.”