Scientists, by and large, oppose culling, mostly because so little is known about great whites. Beyond longevity (up to 70 years) and swimming prowess (one tagged specimen swam from South Africa to Australia and back), everything else is guesswork. Knowledge about the shark's diet, for example, is obscured by the fact that they're easiest to tag near seal colonies. Scientists aren't even sure why the species ventures into Western Australian waters. Australia has two resident great white populations, one on the east coast, one on the south. Starting in September, sharks from South Australia journey up the west coast, and many speculate that they're after the migrating humpbacks. But there's no evidence for this.
There's also no evidence to explain why sharks attack people. None of the theories raging through Margaret River's surf community – a single geriatric shark feeding on slow-moving humans, or sharks mistaking surfers for seals, or exploding populations of sharks – is supported by empirical data. Some scientists wonder about the effects of global warming, noting that increasing water temperatures off Western Australia had strengthened the Leeuwin Current. Has this altered shark behavior? No one knows.
The one thing scientists generally agree on is that shark attacks are completely random events, and that the chances of a bite increase with more people in the water more of the time. "The number of shark-human interactions occurring in a given year is directly correlated with the amount of time humans spend in the sea," says George Burgess. Shark attacks globally (there were 72 in 2013, 10 fatal) have steadily increased each decade since 1900, a trend Burgess attributes to the exploding human population and the skyrocketing interest in aquatic recreation worldwide.
Nowhere do these trends merge more perfectly than in Western Australia. With a population of about 2 million, Perth is one of the fastest-growing metropolitan areas in the world, and the culture revolves completely around sand and surf. It was not unreasonable, then, to suggest the spike in attacks is caused by changes in human behavior, not shark behavior.
The state commissioned a report on whether to adopt a shark-mitigation strategy using drum lines or shark nets. Other places had such programs, but the report ultimately concluded that their effectiveness was impossible to evaluate. It advised against such measures for Western Australia, citing their devastating impacts on both target and nontarget species, including dolphins, dugongs, and turtles.
Instead, the government increased helicopter patrols. It funded research into shark repellents. It enhanced an existing shark-tagging program. When a satellite-tagged shark swims near an array of coastal receivers, beach patrols are notified and word goes out on Twitter. By 2013, Western Australia had tagged hundreds of sharks, including 144 great whites, and developed the world's best shark-monitoring system.
But none of that mattered on November 23, 2013, when what was thought to be a great white killed yet another surfer off Gracetown. It was the sixth fatal attack in two years. It changed everything.
A delegation of surfers and business owners from Margaret River began lobbying intensely for drum lines. Officials moved swiftly. On December 10, Colin Barnett, the state's premier, announced that drum lines would be set off state beaches in a trial program from January through April 2014. All great white, tiger, and bull sharks longer than three meters caught would be destroyed. Federal officials had granted Barnett an exemption from national laws protecting great whites. "I get no pleasure from seeing sharks killed," Barnett said. "But I have an overriding responsibility to protect the people of Western Australia."
Until this point, there had been just three places in the world with active lethal shark-mitigation programs – the Australian states of New South Wales and Queensland, and South Africa's KwaZulu-Natal province, where efforts started in 1937, 1962, and 1952, respectively. New South Wales and KwaZulu-Natal protect their beaches with large-mesh gill nets that catch and kill great numbers of sharks. But Western Australia's swell made nets untenable, so Barnett looked to Queensland, the only place using drum lines. People often pointed to a single, powerful statistic as proof that Queensland's program worked: Since 1853, the state has had 71 fatal shark attacks but just one since the mitigation program started in 1962. "We didn't reinvent the wheel," says Western Australia fisheries minister Ken Baston. "Since 1962, Queensland has used drum lines successfully."
But many scientists are dubious about drum lines. In an analysis of Queensland's program, Jessica Meeuwig, director of the Center for Marine Futures at the University of Western Australia, noted that fatalities have declined in areas both with and without drum lines, and that 83 percent of drum lines are deployed at locations where a fatal attack has never occurred. Another concern for scientists about nets and drum lines is that, regardless of their effectiveness, once installed, they become politically very difficult to remove. "If you're the politician who removes the nets, and then there's an attack, that's on you," says Burgess, of the International Shark Attack File.
None of this swayed Barnett. Drum lines were installed in late January. If officials had any inkling of the three-ring circus that was about to ensue, they only hinted at it. Fisheries staff, while formulating the policy, acknowledged that the state's own commissioned report had advised against a lethal mitigation program, with one official noting, "We will likely cop some criticism if the new policy involves drum lining."
They had no idea.