Suppose your worst-case scenario goes like this: by the time you turn, he’s already seen you, and he’s closing fast. You’ve seen him before too, this great white. Not in the surf, but when you close your eyes, when you glimpse a shadow in the water, this is the shark you imagine: 2000 kilograms of muscle and teeth with the black, dead stare of a killer.

Now he’s really here, and perhaps you’re close enough to see that his eyes aren’t black at all, they’re navy; dark in the deep but in the sun they shine inky blue. His teeth catch the light too. You might see them first, jagged like steak knives. Of course, more likely than not you see nothing but a flash of grey before the bite. It’s gentle, by shark standards. Your leg jerks. You kick out, throw a punch. He lets go.

Now, above the surface, tragedy is unfolding. Lifeguards and panicked swimmers rush to help. But the shark didn't stick around. He's already gone, back into deeper water, with a strange taste in his mouth. So what did he want?

If we were to follow that shark, where would he lead us? Great whites travel thousands of kilometres along Australia’s coastline and beyond every year. Some are tracked by researchers; they have names, or at least numbers, and their own radio frequencies, thanks to tags implanted under their skin and dorsal fins. On the seafloor, receivers listen for them to get close. But they wouldn’t hear this shark. He doesn’t have a tag yet. We’ll just call him Shark 26. (That’s how many years he’s been alive.) For a great white, he’s barely grown-up, one of a few thousand adult whites estimated to be left in Australian waters.

Not all of the 500-odd shark species out there look like Shark 26. Some don’t even look like sharks – our native wobbegong more closely resembles a carpet while the Greenland shark grows large and hundreds of years old in the icy waters at the top of the world.

In the past few decades, tracking programs have started to piece together a new picture of the ocean’s most fearsome predator. Scientists have learnt that sharks, once considered notoriously solitary, are surprisingly social; that some will return to the same stretch of coast alongside the same sharks year after year; that they can learn from each other, remember, and even count; that they might lean in to human touch, lay their head in the lap of a diver or play in the bubbles of their tank.

Researchers also have more than 100 years of shark attack records to help calculate the odds of your worst-case scenario ever becoming a reality. So what do we really know about why these big fish bite?

What are the odds of being bitten by a shark?

You’re more likely to be killed by bees or cows than sharks, says Gavin Naylor, an evolutionary biologist who curates the International Shark Attack File. On average worldwide, just over 80 people a year have run-ins with sharks in so-called “unprovoked attacks”, when the shark seems to come from nowhere, rather than being lured by fishing or bait. About six people usually die.

Consider that number against the many millions of people taking to the water. Or against the tens of millions of sharks killed each year for their meat and fins as industrialised fishing pushes a third of all shark species towards extinction. Even the great white is now endangered.

Still, bites are no less tragic for being rare. By late November 2020, eight people had died in Australian waters alone, making it our deadliest shark attack year since 1929 (when panicked Sydneysiders advocated for dynamiting sharks at Bondi). That’s a very bad year, Naylor says. There were no bite deaths in 2019.

The 2020 tally “really hurt”, says surfer Dave Pearson, who has been running the world’s only shark attack survivor support group, Bite Club, since his own run-in with a bull shark in northern NSW almost 10 years ago. “Whenever you chat to a surfer these days, inevitably the conversation turns to sharks.”

Herein lies the mystery for scientists. If shark numbers are actually going down, why are attacks going up?

Naylor offers two practical reasons: there are more people in the water than ever before, and there are more people reporting encounters than they did when official record-keeping began in 1958. “Fortunately, our medical response times, our [shark] surveillance, is getting much better, so we’re actually saving more [victims globally].”

The shark bite capital of the world is actually a small stretch of beach in Florida called New Smyrna – but so far none of its attacks have been fatal. “Comparing white shark bites to the [main] culprit species [in New Smyrna], a blacktip, is like comparing dingo bites to hamsters,” Naylor says. “You’ve got about a minute-and-a-half before you faint if the big femoral artery [on the thigh] is severed.”

Leonardo Guida, a shark ecologist at the Australian Marine Conservation Society, says a perfect storm of changing environmental conditions might now be driving bigger sharks closer to Australian coast. Warming oceans are shifting the migration patterns of some whales and fish further south – and sharks follow the food. A recent study found climate change was already seeing bull sharks move into Sydney in greater numbers.

At Macquarie University, biologist Nathan Hart and his team examined more than 100 years of Australian attack records against environmental conditions and shark behaviour to develop a world-first predictive model for bites. “It’s a bit like weather forecasting [for sharks],” Hart says. The risk goes up near river mouths where runoff tend to draw them close, or after high rainfall stirs up the sea. And big sharks like to hunt where cool waters meet warm. Shifts in the East Australian Current due to climate change are pushing these nutrient-rich upwellings closer to shore, Hart says. A major hotspot for white shark attacks on the east coast even lines up to the western boundary of the current.

Above: In the US, a reef shark, known as Foggyeye, lets Christine Zenato remove a hook from her mouth – in all, it takes 40 minutes as the shark recoils, swims off, and returns. “She never left me alone after that day,” Zenato says.

Do sharks “hunt” people?

Fifteen years ago, diver Cristina Zenato began removing fishing hooks caught in the mouths of local reef sharks in the Bahamas. Today those sharks will lay in her lap like dogs. Zenato, known to the internet as “the shark whisperer”, says people have made monsters out of sharks because it’s easier to pretend they are not an animal that feels and hurts.

“We’ve done it to wolves and snakes, to bats,” she says. “Three-year-olds are taught to fear sharks, even before they’ve seen the ocean.”

Perhaps it’s because they catch us so literally out of our depth, in their domain. At Sydney’s Bondi Beach, ancient rock carvings depict shark attacks. During a brief but controversial program in 2014, the West Australian government hunted and killed “rogue sharks” thought to have mauled people, as if tracking down wanted criminals.

Leading shark scientist Yannis Papastamatiou agrees that people still see sharks as serial killers. “I’ve swum with whites, with hammerheads, I’ve looked into their eyes,” he says. “They’re not harmless, they don’t care about your feelings, but they’re not out to get you either. They have very basic reasons for attacking, which we still don’t fully understand but we do know it’s not malice or spite.”

While shark attack forensics are still evolving, Naylor says there’s no evidence in the data so far of the same individual shark attacking more than once. Certainly, tagging research suggests sharks move around far too much to be behind numerous attacks. Even the author of the shark attack horror Jaws once penned an open letter pleading with Australians not to buy into the myth of the rogue shark. “Such creatures do not exist, despite what you might have derived from [the film].”

Naylor says in the rare cases such man-eaters have emerged in other species, say, lions and leopards in Africa, the animals were often older, losing their teeth, and no doubt beginning to see an unsuspecting human as easier prey than a baboon. But sharks, like wine, improve with age, growing bigger and more savvy.

We are within the size range of typical fare for a big shark such as a white but Papastamatiou notes that humans have very little fat, or energy-rich blubber, compared with some of sharks’ favourite prey, seals. “For the same reason, you’d be able to tell if I fed you non-fat brownies instead of ones made with real butter.”

Sharks might be styled as the perfect killing machine but, as with most predators, their success rate at catching prey is surprisingly low. “They can burn out very quickly,” Papastamatiou says. “So it makes sense for them to bail out if the animal doesn’t offer much energy or their chances are low.”

Above: This camera is on a grey reef shark as it cruises through a school of barracuda off Palmyra Atoll in the US. Footage by Yannis Papastamatiou.

Then why do sharks bite?

The records do reveal some crucial clues. “The bigger [and so older] ones tend not to be involved in the incidents; they know we’re not food,” Naylor says. “It’s those young, more naive sharks that are starting to transition into eating things like seals and turtles, not just fish, as they grow.”

Papastamatiou has watched sharks hunt all over the world, from whites stalking seals at dawn to grey reef sharks charging into an atoll in French Polynesia after sundown. (“It was dark, dead quiet and suddenly, they sounded like bulldozers, tearing up the reef.“) While he agrees it’s usually the juvenile sharks still learning the ropes involved in attacks, he doesn’t buy the popular theory that sharks mistake humans, often in their sleek black wetsuits, for seals.

A shark, say our white Shark 26, sees in blurry low resolution, like someone who has forgotten their glasses, but his eyes are good for a fish, and even better at night. “It’s a bit insulting to the shark to say they’re bumbling along making mistakes,” Papastamatiou says. “Every now and then, probably, but not all the time.”

Guida agrees. Scientists (including Hart) have shown that sharks are colourblind, putting an end to old fears about “yum-yum yellow” attracting them to surfboards, but they can still make out contrast and contours. “Even something as small as a cigarette packet floating on the water, sharks will check out,” Guida says.

And sharks are notoriously curious – investigation or taste testing is considered a likely motivation behind many attacks. “They don't have hands, so how do you investigate something if you're a shark? You bite it,” Papastamatiou says. “Of course, it can still be devastating.”

This might also explain why human encounters with the predators typically look very different to a shark truly in hunting mode. When a white such as Shark 26 has spotted a target, he will barrel to the surface in a burst of speed so powerful he’ll often breach out of the water himself. His eyes will roll back in his head to protect against an errant flipper or tooth.

“If sharks went after surfers the same way they went after seals we’d be seeing a lot more fatalities,” Papastamatiou says. “Some attacks may just come down to how hungry a shark is, but very rarely do we see actual consumption.”

Many sharks will leave after biting a human rather than charging a second time or waiting for the victim to bleed out, as they often do with their regular prey.

Still, there are aberrations that haunt the public memory. The shark that mauled Ken Crew in the shallows of a Perth beach in 2000 then turned on his rescuer. Pearson says some Bite Club survivors have been bitten more than once or chased back to shore. “We’ve had a shark bump someone else out of the way to go for one of our guys,” he says. “And I’ve spoken to about 10 people thrown metres into the air in a stealth breach attack – thankfully, the surfboards took the brunt of it.”

In Tasmania in 2020, a boy was dragged from a fishing boat by a breaching white shark but rescued with only minimal injuries by his father as the shark let go. Papastamatiou says the boat itself, rather than the boy, was probably the target. “But it’s really guesswork, why it attacked.”

Hart notes many victims are surfers, who tend to be further out in the deeper water where bigger sharks dwell. But he thinks the mistaken identity theory shouldn’t be discounted too quickly – his own experiments carting foam seal “decoys” behind boats for white sharks in South Africa found that when the foam seal was outfitted with a flashy strip of lights, disguising its familiar silhouette, the sharks stayed away.

“And someone on the surface can look pretty similar to our foam seal.”

It’s also unclear if sharks are territorial, Papastamatiou says. “Some do have home ranges and … hierarchies. You’ll see injuries from other sharks, a white might charge another one to let it know to back off, though I’ve never heard of [these clashes] being fatal.”

But, while some of the smaller sharks may perceive us as a threat, he says the bigger species involved in most incidents (bulls, whites and tigers) are unlikely to feel threatened by an ungainly human in their ocean.

“We need to look, too, at all the times a shark was there and nothing happened. If people knew how often there was one in the water with them, they’d be shocked.”

What have we learnt from close encounters?

Australian champion surfer Mick Fanning famously fended off a white shark live on television during a competition in South Africa, and recalled later how he felt the predator move behind him as he tried to swim for shore. Some instinct told him to whip back around, to fight with his fists, rather than turn his back.

Papastamatiou, himself trained in martial arts as well as diving, admits the old punch in the nose advice likely won’t do a whole lot of good. “Obviously, you should fight back, but if I had a choice I’d be going for the eyes or the gills; they’re more sensitive to damage. My Brazilian jiu-jitsu probably won’t do much at all unless I wanted to put the shark in a headlock – definitely not advisable.”

Instead, he says, think like Mick: “Never turn your back on a shark.” If a shark thinks it can catch you unawares, you’re a much more interesting prospect than someone vigilant who might give it a fight. Papastamatiou has seen sharks bail out of charges just because a turtle glanced up and spotted them.

Pearson shudders to imagine how he would have reacted if his own encounter with a bull shark hadn’t happened so fast, if he’d looked it in the eyes as it broke out of the water in front of his surfboard. What he remembers instead was the gaping teeth and, later, a grey shape in the roiling surf. The shark’s nose clocked Pearson in the head and his left arm became stuck between its jaws and his board as they were dragged underwater together, man and shark. “I wouldn’t say we were wrestling exactly,” Pearson recalls. “We were both stunned from the [collision so] it did the hard work for me.”

In the years since that day, Pearson has come hair-raisingly close again and again to large sharks in the waters of NSW – 12 encounters within his first 12 months back in the water. A white “sniffed [his] feet” all the way in on a wave. A bull rubbed its back against him.

Some close calls were easy to shake off. Some weren’t. “I’d tell [my mates]: ‘Don’t leave me alone.’ Sometimes I just sat back on the beach and cried, thinking, can I keep doing this? Now I’m more settled, my love of the ocean is still stronger than my fear of sharks. But they don’t call me shark bait for nothing; I seem to have a radar these days. I know when to get out ... People need to listen to sightings.”

In the documentary Save This Shark, Fanning himself gets close to some of the world’s biggest sharks in an effort to understand what happened that day in South Africa and how the predators, which he now calls “the janitors of the ocean”, are faring against overfishing. “I think people expected that I’d be calling for a cull on sharks, but it’s the opposite,” Fanning says. “I learnt to dive so I could get closer to the sharks and resolve the feelings I had … Hopefully, [now] I’ll be known less as ‘the guy who punched a shark’ and more as an ocean activist.”

Shark biologist Charlie Huveneers took Fanning cage-diving with whites in the Neptune Islands, a known hotspot for the species in South Australia. It was in these waters that Huveneers and his team first noticed whites seemed to be using an interesting tactic to hunt – coming at prey from the same direction as the sun to seemingly improve their vision (and dazzle their target). They even changed direction as the sun shifted throughout the day.

“World War II jet fighter pilots did it too,” Huveneers says. “But we hadn’t seen it with a marine animal before.”

What do we know about how sharks think?

When Zenato takes tourists on reef dives in the Bahamas, she is also followed by a group of loyal “regulars”; sharks she gives names such as Grandma, Stumpy and Shredder. Some are more “popular”, others must be coaxed in for a feed, cheekier animals might be scolded for stealing bait. It’s like the whites Papastamatiou works with in Mexico; certain animals will swim calmly to the boat, he says, “and others are just – there’s no other word for it – bad-tempered”.

Researcher Catarina Vila Pouca has seen the same surprising personalities surface in (smaller) sharks she’s trained back at Macquarie University’s Fish Lab. Some of the Port Jacksons on which her team ran cognition experiments were bolder than others. The sharks could also learn from one another, recognise patterns and even count (in a sense), identifying specific quantities of dots on cards.

It’s likely such skills translate to bigger species too, Vila Pouca says, as they seem key to survival. “There’s a whole range of abilities science has assumed only happened in mammals we're now testing in fish. People think fish have terrible memories, but sharks can learn things and remember them for more than a year.”

There are also signs of learning in the wild, she says. It’s why fishermen will often complain of sharks stealing fish straight off their hooks or following their boats, and why tagged sharks released by scientists will often shoot off into the open ocean and not return to shore for months.

Huveneers says that personality and unpredictability can even show up in migration patterns. Sharks are constantly moving, not just to hunt but to return to preferred breeding grounds – usually in more sheltered reefs and mangroves where baby sharks born tough but small can be safe to fend for themselves. They don’t travel in packs but many species have been known to come together in small “clans” year after year.

“There’s even this mysterious bit of ocean off Hawaii, in the middle of nowhere, that white sharks near the US gather at the exact same time,” says marine biologist Olaf Meynecke. “We call it the White Shark Cafe. In the shark world, usually the bigger sharks move around more, but we still don’t quite know how they find each other again in all that vast ocean. It’s like a desert.”

Whites are found in every ocean on Earth. Those in Australian waters will often swim across to New Zealand, New Caledonia and the Pacific Islands. One now-famous white named Nicole (after the actress and shark enthusiast Nicole Kidman) was tracked from South Africa to south-west Australia and back again in nine months. In recent years, the CSIRO has started building a white shark family tree of Australasia using DNA samples from tagged animals. “It’s like ancestry.com, but for sharks,” a spokesman says. Analysing that data, they could estimate the true size of Australia’s white population for the first time, he says, and found it has stabilised over the past decade since protections were introduced but remains in trouble – short on breeding partners.

Why are sharks in trouble – and how do we live with them?

Sharks have swum in our oceans for the past 450 million years – their ancestors fought the dinosaurs. They are finely evolved to hunt at the top of the food chain. Zenato calls them the wolves of the sea, stopping any one species from getting out of hand and throwing off the ecosystem below.

The problem for sharks is that they also mature and reproduce very slowly. So if their populations start to decline rapidly, as they are today under unprecedented overfishing pressure, they cannot make up for the losses fast enough.

Naylor muses that, while sharks have already survived four of the five big extinction events on Earth, and will likely survive climate change too, “the one thing they won't survive is being fished out of the water by a bunch of monkeys, [without] end”.

“And there will be consequences if we remove sharks; we don’t know exactly what yet. It could be algae all over our beaches, blanketing the Gold Coast. It could be much worse.”

In the Bahamas, shark numbers are stable thanks to new protections, but they still regularly find themselves snared by hooks after being drawn to fish thrashing on lines.

“It’s the job of the shark to clean up what is hurting, what is bleeding,” Zenato says. And she now considers it her job to help them where she can.

Removing hooks from the mouth of a shark is not easy. “People say, ‘Use pliers’, I need to use my hands.”

Sharks outside her regular group will turn up on dives with hooks too. “And I’ll take them out and never see those sharks again. But they know to come.”

Guida has studied the impact of shark mitigation and fishing methods on animals, measuring the build-up of chemicals in their bodies during capture. “A shark jerks just like a human when I draw blood,” he says. “Their brains, their physiological responses to pain and stress are not that dissimilar to ours.”

Even in the Great Barrier Reef World Heritage area, Guida says fishing nets can stretch for more than a kilometre. “Once something’s in a net, on a hook, flopped up on a boat or trawler, it becomes a race against time. Some species that need to swim to breathe, like the [endangered] hammerhead sharks, start choking fast.”

Marine biologist Lawrence Chlebeck at the Humane Society International says living with sharks safely is not about shark-proofing the ocean. “That’s a very Australian idea,” he says. “[Bites] are horrific, and they make us think authorities should do something, but the way to stay safe isn’t what might feel right; it’s not [vengeance].”

Research consistently shows that killing sharks – through netted beaches, baited drum lines or bullets – doesn’t stop attacks. In some cases, sharks and other marine life caught, such as turtles and dolphins, might even attract more predators to the area. In others, Guida says the measures can create a false sense of security for beachgoers. (“The nets, for example, only go up four metres.“) The death of a surfer on the Gold Coast in September was at a beach with both nets and drumlines, although proponents insist overall deaths remain low at netted beaches, even if attacks have not slowed.

Scientists now see real promise in shark surveillance programs being rolled out from South Africa to WA and NSW. In October, a loud warning from an overhead drone may have saved professional surfer Matt Wilkinson from a shark that had swum close without him noticing.

“I’m saving up my pennies for my own drone,”Pearson says. “And there’s nothing like surfing with five or six survivors – one splash and every head snaps around.

“The big question we all wonder – why did it happen? – we never really get an answer to, so [as a group] we’ve become each other’s answer.”

As Zenato describes the swollen jaws of the sharks she helps by hand, she stresses that she understands the risks (“I would never try to remove a hook from a great white”). But still she wonders, when the animals sink down into her lap, do they enjoy her touch? The protective chainmail she wears over her wetsuit is soft against the skin.

It’s the same way we might wonder if a 500-year-old Greenland shark, born before the Industrial Revolution, has felt the ocean warming in the centuries since, as pollution spilled black and sticky into the seas.

“At the end of the day, it’s a wild animal, who knows?” Guida says. “But I remember now cage-diving with a white and in the whole 45 minutes she was close, she only bared her teeth once. It just struck me how gentle they can be, how shy they can seem.”

Zenato thinks the reef sharks come to her because they feel no threat. “Some stay for a very long time, some just a few minutes. But in that moment, they trust me.”

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