Expert doubts WA government's chances of catching shark that killed swimmer

A leading behavioural biologist and shark drone expert has expressed doubts about the Western Australian government's decision to issue a catch-and-kill order for the shark responsible for the death of a 63-year-old swimmer at Sorrento Beach in Perth's north.

Culum Brown, from Macquarie University's Ecology and Evolution of Fishes Laboratory, said the chances of finding the shark responsible for Greg O'Neill's death were like finding "a needle in a haystack".

"The reality is that white sharks move a long, long way, they are literally on the move all the time … by now, that shark could be hundreds of kilometres away," Mr Brown said.

The WA government issued the catch-and-kill order under "the exceptional circumstances of the attack", where "the hazard posed by the shark" and "the potential recovery of coronial evidence" were taken into consideration, according to Fisheries Minister Jackie Jarvis.

Ms Jarvis said the government would first review its current mitigation strategies — which focus on tagging and tracking, an app for notifications, warning sirens, shark enclosures and personal deterrents — to see what more could be done to protect beachgoers.

Mr Brown suggested that investing more funds in shark-spotting drones would be a better response, an approach that has been taken by the New South Wales government.

"They [drones] are just a very highly effective technology," Mr Brown said. "They are a lot cheaper than fixed-wing or helicopters … and one of the many benefits is that you can intervene before the shark attacks anybody and … there's no bycatch as there is with shark nets and things like that."

Ms Jarvis added that deploying more drones to spot sharks along WA's vast coastline was "absolutely under consideration".

The body of Mr O'Neill is yet to be recovered, and authorities are still searching for it.

A woman has laid a floral tribute alongside others at Sorrento Beach after the fatal shark attack.

WA Deputy Premier Rita Saffioti said she "100 per cent" supported Ms Jarvis's response to the attack, including the catch-and-kill order.

"The minister made a decision based on advice. That advice was given by, as I understand, both police and fisheries," Ms Saffiotti said.

WA Greens healthy oceans spokeswoman Sophie McNeill earlier criticised the order, describing it as cruel and ineffective, and called for more funding for shark-spotting drones and helicopters, and an expansion of the shark tagging program.