Mike Psillakis’s twin brother, much-loved and experienced surfer Mercury, died in a white shark attack off Long Reef in September last year.
After last weekend’s attack at Coogee Beach, and summer’s spate of bull shark bites, his attention has turned to the Indian Ocean paradise of Reunion Island. Located between Madagascar and Mauritius, the French locality has seemingly quashed what residents called la crise requins: “the shark crisis”.
Thirty shark attacks plagued the tiny island between 2011 and 2019. Eleven were fatal, making up 18.5 per cent of global shark deaths. Officials banned swimming and surfing.
Since 2019, however, not a single shark attack has been recorded in the waters surrounding Reunion. One of the mitigation efforts brought in – among a raft of other measures – was a program by which adult bull and tiger sharks were hooked by SMART drumlines and killed rather than released.
“They didn’t wait for data on shark populations to take that next step of lethal drumlines,” said Psillakis, a surfboard maker. “The last attack was ‘enough is enough’.
“We have to use our drumlines differently. We have to use them in the same way Reunion Island uses them. We’re not talking about decimating or making a species go extinct. We’re just there to control the populations.”
Shark safety is under the spotlight after Coogee teacher Leah Stewart was mauled by a white shark last Saturday. She lost an arm and has undergone complex surgery, with wounds contaminated by sand and debris at high risk of infection, her brother said on Wednesday.
Premier Chris Minns has ruled out killing white sharks because they are a migratory and protected species. However, he said a bull shark “headcount” would examine if populations have increased – something currently unknown – and his government would consider a cull.
But Psillakis said Reunion Island acted on attack rates, not shark numbers.
“I think we have to look at the death rate of people rather than the population rate of sharks. That’s probably the most important thing.”
Australia and Reunion have engaged in a kind of technological exchange since the 1960s. Queensland’s method of using baited drumlines to cull sharks have been used on the island. In return, the higher-tech SMART drumline technology now used in force across NSW was designed in Reunion.
Where the traditional baited drumlines kill sharks – and many other harmless species – SMART drumlines alert contractors who can respond to a hooked creature and decide what to do with it once it’s identified.
In NSW, sharks including white, bull and tiger sharks are tagged and moved a kilometre offshore. In Reunion, adult bull and tiger sharks – the species behind the island’s attacks – are euthanised.
The problem facing policymakers, scientists and the public is that it’s difficult to prove whether, and to what degree, these moves decrease the risk of shark attacks.
While bull sharks are also migratory, they travel a predictable path each year between Queensland and NSW. That means they are already the subject of lethal control because Queensland has never stopped hooking sharks with traditional drum lines. About 130 bull sharks are killed each year, according to marine ecologist Lawrence Chlebeck from the Humane World for Animals.
A KPMG report found that between 2021 and 2024, an average of 438 target sharks (including bull, tiger and white sharks) were caught on drum lines off Queensland, up from the 350-per-year average between 2001 and 2021. At the same time, annual shark incidents fell from 3.35 to 1.04.
The report flagged that the trend was correlative and didn’t prove the lethal drumlines had reduced attacks, the ABC reported. But the Queensland government expanded the use of nets and lethal drumlines regardless.
“They’re making a correlation that’s just not there,” said Chlebeck, who added an increase in shark populations does not necessarily correlate directly with shark bite risk.
His organisation took the Queensland government to court to stop the lethal shark control program within the Great Barrier Reef Marine Park. The Administrative Appeals Tribunal found in 2019: “The lethal component of the [shark control program] does not reduce the risk of unprovoked shark interactions. The scientific evidence before us is overwhelming in this regard.” The lethal program was halted in the marine park but continues elsewhere.
Most scientists have said killing sharks does not reduce attacks. “The efficacy of culling varies between species and regions, and the number of sharks needed to be culled is unknown but is likely to be high before it starts affecting shark-bite risk,” Professor Charlie Huveneers wrote in The Conversation.
Many shark researchers support beach-scale mitigation techniques such as non-lethal SMART drum lines (where sharks are moved, rather than killed) and drones. Testing the efficacy of these interventions is challenging, but more realistic than ascertaining whether lethal shark control makes people safe.
“We need to be focusing on what we can do at the actual beaches where people are swimming,” said Bond University shark expert Daryl McPhee. He said it was very difficult to make a statistical link between lethal shark programs and bite risk.
The extreme rarity of attacks is one major statistical challenge that makes it hard to tease out meaningful patterns.
Some research from the 1990s linked use of nets and lethal drum lines to fewer shark attacks. Other large-scale studies have found no such effect, including analysis of shark control during the 1960s and ’70s in Hawaii, in which 4668 sharks were killed but there was no reduction in attacks.
More recently, scientists have identified 40 factors that influence shark bite risk, from human population increase to worsening water quality.
Another study, led by Huveneers, noted there were no human-shark interactions at NSW beaches operating drones and non-lethal SMART drum lines. “We recommend that additional monitoring of these gears for at least another 10 years is required to determine if there is evidence for any effect,” the authors wrote, underscoring how long it takes to gather data on mitigation methods.
Psillakis is a vocal supporter of year-round drone deployment.
In Reunion Island, the culling program is in use alongside nets, boat patrols, shark-spotting divers and automated AI-powered shark detection cameras. The island’s SMART drum lines caught and killed 68 bull sharks and 543 tiger sharks between 2018 and 2025, according to Science.
Island authorities have handed data from the culling program to independent scientists, who will scrutinise the drum lines’ effect on biodiversity and what role they may have played in reducing shark attacks.
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Angus Dalton is the science reporter for The Sydney Morning Herald.Connect via X or email.
