How an AI-powered early shark warning system could protect Sydney beaches

An early warning system to detect sharks off popular beaches and sound the alarm could be in place by summer if the NSW government ramped up its existing $30 million shark mitigation strategy, scientists say.

The call comes as Premier Chris Minns said a cull of Sydney’s bull sharks was being considered while ruling out such a measure for white sharks. Minns on Monday said he wanted to vastly scale up beach patrols by automated drones after the mauling of a swimmer by a great white shark at Coogee Beach.

Professor Culum Brown from Macquarie University said an early warning system could use existing technology – autonomous drones with on-board sensors and artificial intelligence to detect sharks.

“You can have it so once the drone recognises a shark, it could potentially lock onto it, follow it and start flashing and making noises,” Brown said. “At the same time, it can send an information package back to the base, and then, on the beach, you could have speakers saying, ‘There’s a shark in the water, everybody get out’. It’s not rocket science – it’s actually pretty straightforward to do that sort of thing in this day and age.”

Brown said the most basic form of the AI might activate the warning based on the size of the shark, but it would not take much to train it to recognise different species. His research unit had AI that could identify 40 different fish species from drone footage.

Brown said the drone program was limited because a qualified pilot was needed to fly them, but this was “completely unnecessary” because they could be pre-programmed and fully automated.

Emeritus Professor Rob Harcourt at Macquarie University said the autonomous drones and AI shark recognition technology were both either available or close to available, and he expected the NSW government to implement them as soon as possible.

“These things do cost, of course, but I suspect that the general public is more than happy to bear that cost because we really don’t like being bitten by sharks,” Harcourt said.

The NSW government already spends more than $30 million a year on shark mitigation, including a $6.7 million increase last summer.

Surf Life Saving NSW chief executive Steven Pearce said the organisation ran autonomous drones from its head office in Belrose in remote areas, but prioritised having drone pilots on the beach where possible.

“From a community perception, they have more comfort and confidence if they can actually see a drone pilot on the beach flying the drone, so they know drones are there, and our pilots are specifically uniformed up in our red and yellow uniforms, so people can immediately recognise that they’re pilots from Surf Live Saving NSW,” Pearce said.

Pearce said Surf Life Saving NSW was the largest shark surveillance program operator in the world, with more pilots, doing more flights and seeing more sharks than any other entity. However, the program peaks in summer with 80 sites, and that fell back to 13 sites in winter when beach visitation was traditionally lower.

“We’re seeing obviously warmer temperatures each winter ... and there’s more people in the water,” Pearce said. “It would be pertinent to start to explore how we can extend the drone surveillance programs to replicate what we see in the summer as well.”

Pearce said Surf Life Saving NSW was ready to expand the drone coverage “as far and as wide as government wishes us to take it” before next summer.

Drones were not used at Coogee before the weekend because of restrictions related to the area being under the flight path. An emergency exemption was granted on Sunday. Pearce said this would continue indefinitely, and he would work with the Civil Aviation Safety Authority to fine tune the arrangements.

Minns said he did not think the ban on drones at Coogee Beach before the attack was an example of regulatory overreach. However, he said: “If I had my time again, we would have pressed for CASA’s removal of it before Saturday.”

“This is going to be part of a longer term solution for beach safety – to have permanent drones, whether they’re tethered to the shore or they replace themselves when they run low on batteries,” he said.

“Technology is getting to the point where they can identify marine life from whatever distance.”

Pearce said it was still human operators – either on the beach or at head office – who identified the sharks, but Surf Life Saving NSW had been working with the government to try to identify an AI solution with acceptable accuracy.

Pearce said there were only three shark species of concern – whites, tigers and bulls – and he would not want too many false positives that evacuated the water for dolphins, grey nurse sharks and wobbegongs. “We would be reticent about the continuous closing of beaches or the sounding of sirens for incidents that aren’t deemed dangerous,” he said.

Harcourt said we were “halfway there already” to having an early warning system because it could also draw in information from the shark listening stations along the NSW coast which detect sharks caught on the SMART drumlines.

The listening stations fed information on movement of tagged sharks to the SharkSmart app and to Surf Life Saving NSW for operational use. Harcourt said in a few years the system would be able to predict where the sharks would go next.

On Monday, Minns ruled out culling white sharks, citing the species’ protected status and migratory behaviour. But it may be on the cards for bull sharks, thought responsible for a spate of attacks during the summer, including the one that killed 12-year-old Nico Antic in Vaucluse.

“As it relates to bull sharks in the harbour, that’s a different story,” Minns said. “They’re not a protected species, and we’re currently undertaking a head count – effectively, whether there’s been an increase in the harbour as a result of a healthier harbour and more fish stocks within that tributary.”

Brown said local culls would not work with species that swim such large distances.

“It’s like trying to dig a hole in dry sand – you can take a handful of sand and the sand’s just going to cascade back into the hole,” Brown said. “You’d have to generate a massive regional decrease in shark numbers to have any impact.”

Bull sharks were only present in Sydney during the warmer months and then swam to Queensland for winter, Brown said, and recent evidence from the Queensland shark control program suggested their numbers were declining.

Harcourt said sharks were already being culled because the mesh nets installed from September to March were a culling device that “unequivocally depressed” shark numbers.

“We’ve been culling them for nearly a century now, so the change in risk that’s likely to come from culling is probably already there,” Harcourt said. “Any change in the number of bites is much more likely to be the fact that our use of the ocean is continually increasing and so is our human population.”

The NSW government shelved plans for a trial to remove mesh nets after a shark killed surfer Mercury Psillakis in Dee Why last year.

Minns said on Monday he had become convinced shark nets were a deterrent and remained an important mitigation measure.

“We’re not going to be removing them during summer, and we’re investigating what are the safer periods to have them in place.”

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