The Western Australian government is jeopardising beach safety by using tagging data to track a great white shark it has marked for culling, a shark expert says.



The state’s Department of Fisheries announced on Friday that it would deploy capture gear to “take” a tagged white shark that had been repeatedly detected by the acoustic receiver at Warnbro Sound, near Rockingham, about 50km south of Perth.

In a statement, the department said the shark had “been assessed as posing a serious threat to public safety”.

But a University of Sydney shark policy expert, Dr Christopher Neff, said classifying a shark as an imminent threat on the basis of scientific tagging data went against the purpose of tagging, which was to study their movements as an indication of what the wider, untagged shark population might be doing.

He said using that data to track and kill a white shark was unheard of and had angered scientists.

“Tagging provides an early warning system, and by killing that shark you are killing the early warning system,” he said.

“It’s a step backwards for science and for beach safety.”

The tagged white shark, believed to be female, has been detected swimming near the Warnbro Sound receiver for about two weeks. Each detection by the receiver has been broadcast on the Surf Life Saving WA Twitter feed, and the government’s SharkSmart website. The last detection was at 3.48am on Sunday.

Drumlines were put in the water on Friday, Saturday and Sunday, catching a tiger shark and a stingray. Warnbro Beach has been closed.

Under WA’s “imminent threat” policy, sharks are considered to pose an “imminent threat to public safety” if they are reasonably suspected to have been involved in an attack, or if they are of a species “with a history of attacking people” and have repeatedly been sighted near a popular beach during daylight hours.

Neff has repeatedly criticised the “imminent threat” policy, describing it as a false belief in the existence of “rogue” sharks that has more to do with the movie Jaws than scientific evidence.

He told Guardian Australia he was labelled “hysterical” in September 2012 when he predicted scientific tagging would be used to catch and kill sharks under the imminent threat policy.

Neff said the director of government media in WA, Dixie Marshall, wrote in an email to him at the time: “We – the state government of WA – are not using scientific tags to track and kill white sharks.”

The government’s Shark Hazard Mitigation Decision Sheet, published in November 2012, also warns against killing tagged sharks, saying: “Capturing a tagged shark may eliminate a key indicator of a temporary high hazard in the proximity of a popular beach.”

Natalie Banks, from No Shark Cull, said the shark had been detected by the Warnbro Sound receiver, which is 800m offshore, almost 100 times before the threat it posed was considered imminent.

She said it had been feeding on spawning snapper about 1km offshore.

“If you close the beach, there’s no imminent threat. If you inform the public that the beach is closed and why, there’s no imminent threat,” Banks said.

In a statement to Guardian Australia, WA Fisheries acting director-general, Rick Fletcher, revealed that the decision to catch and kill the shark had been prompted, at least in part, by the onset of the school holidays.

“The initial pattern of detections of this tagged shark combined with mitigation strategies did not warrant further action initially,” he said.

“However there was an increase in the number of day-time detections on consecutive [days] during the lead up to Christmas, and school holidays combined with warm and sunny weather, people are more likely to be in the water using the beaches, fishing and diving.”

The imminent threat policy was also used to justify the killing of two white sharks in Esperance after Bunbury surfer Sean Pollard was attacked on 2 October, losing part of both arms. One of those sharks had been tagged.

WA fisheries minister, Ken Baston, responded to Guardian Australia’s request for comment from Marshall.

Baston said: “the correspondence referred to (between Marshall and Neff) was provided by way of background information in response to some communication from Dr Neff”.

“That correspondence was not for publication and it was provided as way of background,”he said.

“There is nothing inconsistent in the statement of 2012 and what occurred over the weekend.”