On a whisper-still January dawn, the most terrifying day of Allan Oppert’s life began unremarkably and with a feeling of deep calm.

Like most Sundays, he woke to a knock on the door from his friends Dan and Dave. At Allan’s neat house in the small seaside town of Binningup, in the south-west corner of Western Australia, the three men drank strong coffee before towing Allan’s boat to a nearby ramp where three friends were launching another vessel. The two groups were heading out on the ocean together, a familiar arrangement aimed at ensuring safety.

Oppert turned the key on his boat’s engine as the western horizon illuminated a glassy sea, a low swell barely bothering the shore. At the height of an Australian summer, mornings on the ocean offered early respite from the baking heat and unrelenting wind of the afternoon. The two boats were heading to a dive site that the men visited most weekends of the year, conditions allowing. A 15-minute boat ride from shore, the site featured a roughly cylindrical cavity about 6m wide and 3m deep on the ocean floor. In 33m of water, the “crater” bristled with crayfish, a delicious but formidable-looking crustacean prized for its sweet, delicate flesh. After several hours and two separate dives into the heart of the crater, a single tank of air remained between the six men.

A great white shark. Photograph: Lauren Smith

I said to Dan, ‘You go,’ and he said, ‘No, you go.’

After entering the water for his third dive of the day, this time alone, Oppert, a 42-year-old prison officer, began his descent. The process, as always, involved the release of air from inside his buoyancy vest to enable heavy weights strapped to his hips to drag him from the surface to the ocean floor. But this time he didn’t quite make it. The torpedo-shaped bulk of a huge great white shark inside the crater below loomed into view and, in the nanosecond that followed, Oppert registered both the animal’s curious demeanour – “like a dog on a scent” – and a firm belief that his life would not end there.

[The shark is] going over to one spot and having a look and going over to another and having a sniff. These sharks are like dogs, in their gestures and in their behaviour. They hunch up their backs when they are annoyed, and she was annoyed. All of a sudden, she’s spun around. I got about halfway to the bottom. [I thought,] ‘She’s going to attack from the back or she’s going to attack from the side.’ The funny thing is that I didn’t think about dying.

An uncannily cool head gave Oppert the presence of mind to reinflate his buoyancy vest, preventing further descent. (Days later, while examining his equipment, he noted the depth gauge registered just 17 metres.)

Considering that great white sharks have been clocked swimming 13 metres a second, it is no surprise that the impact of the strike instantly pulled Oppert’s face mask down around his neck.

It happened in a split second. The mouth’s opened up and she’s hit me in the guts with her nose. I thought: ‘Oh, here we go.’

But he kept his regulator – the mouthpiece that delivers air – firmly between his teeth. Throughout the dog-like shaking of his body that followed, he managed to pull the mask back over his face and purge it of water, returning terrifying visibility – an intimate view into the gelatinous gill slits of the world’s biggest predatory fish.

I thought to myself, ‘Whew! It’s big!’ She was clenched down on both legs and the teeth were through to the bone. The pressure was so great that I thought if it gets any tighter, they’ll snap – she’ll snap both my legs off.

Oppert’s steel speargun, which that morning had shot some large fish, was at the moment of the attack positioned across his thigh. It would be fair to surmise that the very implement that probably attracted the shark in the first place – by prompting fish distress signals that can travel far across the ocean – also helped to preserve his life by preventing the shark’s teeth from gaining full purchase above his knee.

Sunset at Binningup beach.

Photograph: Mik Rowlands/Alamy Stock Photo

When the shark released its grip, the inflated buoyancy vest sent Oppert shooting to the surface, where he raised the alarm and was pulled to safety.

Like many others in Western Australia at the time, Oppert was well aware of a fatal shark attack that had occurred four years earlier on a suburban beach about 150km up the coast. A middle-aged man had been mauled in shallow water in front of dozens of onlookers. But in the years that followed the death of Ken Crew in 2000 – the first such attack in living memory – many West Australians held the view it had been a one-off event, a freakish aberration caused by a “rogue” shark that had “mistaken” the swimmer for a seal. With no subsequent fatality to spook him and no inkling that an attack would kill a surfer further down the coast just six months later, Oppert had descended without a care in the world. It was a decision that nearly cost him his life and has left him 14 years later with the still visible scars from the multiple puncture marks of a shark’s teeth on his legs.

‘This damn big shark’

Ken Crew’s death in the state capital of Perth changed the city’s notion of itself as a beach-lover’s paradise. It marked a moment of horror that still resonates.

Eighteen years on, first-person accounts of those who swam with Crew and witnessed his death continue to have an effect on me, particularly those of his friend Jerry Ventouras.

I turned around and saw this enormous fin travelling on the inside of Ken. It came in behind him. It was surreal. This damn big shark – somewhere between five metres and six metres – head up out of the water, its jaws wide open surging towards Ken. Without even stopping, [it] seemed to grab him across the lower half of his body, lift him out of the water and give him a couple of shakes like a dog would shake at a bone, [and then] dropped him in the middle of the pool in a great cloud of blood. There was no sound.

The Pylon off Cottesloe beach in Perth. Photograph: Smudger Scammell/Alamy Stock Photo

West Australians were slow to forget what they learned about great white sharks that day. For most of us, venturing into the open ocean is a matter of idle leisure no more. But the state’s transition from heedless to near-hysterical has been a while in the making.

Between September 2011 and July 2012, five people were killed by white sharks. Their deaths brought a tangible sense of panic and turned WA into an undisputed white shark hotspot. With each new encounter, swimmers, surfers and divers have become both more jittery and polarised in their views about what should be done.

The WA government has installed measures to help protect ocean users. A network of 30 satellite-linked shark monitoring receivers, which signal the presence of tagged sharks, is one line of defence, in addition to the introduction of non-lethal “smart” drum lines – a system in which sharks are baited on a hook, then tagged and released offshore.

This summer, some of WA’s most popular surf breaks will be linked for the first time to this broader network of receivers, and smart drum lines will be trialled. This follows the cancellation in April of the high-profile international surf competition the Margaret River Pro, after two surfers were attacked by great white sharks just hours, and a few kilometres, apart.

A shark attack victim being airlifted to the Royal Perth hospital.

The situation became untenable when the Brazilian pro surfer and current world champion, Gabriel Medina, told his 6 million Instagram followers he didn’t feel safe competing in Margaret River – an Australian surfing mecca.

Despite bolstered aerial surveillance, smart drum lines and the addition of further shark monitoring receivers, confidence is far from buoyant. Most surfers and divers understand that only tagged sharks moving into specific swimming and surfing areas can be pinged. In WA, that’s 450 sharks, of which 290 are white sharks.

A separate problem is that many south-west surf breaks are located in deep water above dark substrate, making shark-spotting from the air almost impossible. But Surf Life Saving WA’s ramped-up drone monitoring program is finding plenty of sharks, and more surfers and swimmers are staying informed about problem areas via SLSWA’s Twitter feed.

Survivors of shark attacks and their families often lament the fact that sharks were spotted in the area hours or days beforehand and, had they had known this, they would never have entered the water.

‘Felt like a brick wall’

In contrast to Allan Oppert’s lack of concern about the shark risk, as he descended for his third dive of the day in 2004, Bernie Williams certainly did worry and was relying on his dive buddy’s shark shield (a device worn on the ankle that emits an electromagnetic field to deter sharks) on the 2006 morning he met the protagonist of his worst nightmare.

The then 46-year-old contracts manager was on his second dive looking for exotic shells and crayfish with his friends Brian and Jenny, in 20m of water 6km off City beach in Perth. About 15 minutes into the dive, he heard an approaching boat. Sensing it had pulled up close to his own unoccupied vessel and that keys and wallets may be the target, he ascended to briefly check on the visitors. Satisfied that they seemed happily preoccupied with a matter on the opposite side of their boat, Williams descended once more. What he didn’t know on that choppy January morning was that the visiting boaters – who had been fishing nearby when a huge shark appeared beside their vessel – had come to warn him and his dive buddies about the danger. They had been looking for dive bubbles over the side of their boat when Williams briefly surfaced behind them, then quickly descended again.

Back on the ocean floor, Williams found that his friends were nowhere to be seen. So he bounced about two metres off the ocean floor to clock their position. Mid-bounce he was struck from behind with an immense force.

I am not very small and for something to take me from zero to 100km an hour in a fraction of a second, bending me double, you think, ‘God, have I been hit by a submarine?’ It came up from below, behind, and rammed me, just hammered me. When I first got hit I was winded, picked up by the left arm and pushed through the water so the visibility went. I was stunned, didn’t know what was going on. I had a dead weight hanging off my arm. Your peripheral vision in a face mask is nothing [so] when it slowed down a bit I could swing my head around. Then the bells went off. A shark’s eyeball literally filled my face mask. I remember looking down its side when it was swinging me around like a dog with a goanna and I noticed my flippers were about half-way down its length. A big shark. It was just so solid. Felt like a brick wall.

Apparently hampered by the position of the spear gun along Williams’ left side, the animal released its grip and the diver found himself on the ocean floor, where he quickly took refuge in the recess of a reef ledge.

I tucked up against a wall. I remember kneeling on the sand and [the ledge] came up to just over waist height. I was hunched down but there wasn’t enough room for me to get everything in there. I was really puffing hard, breathing like a steam train, beginning to hyperventilate. I remember hearing my heart banging. Banging away, banging away. Thinking to myself, ‘I’m dead, I’m dead, I’m dead. This thing has got my name punched … it’s not going away.’ I was that close to going to the dark side – going into a blind panic, close to saying, ‘You can’t do anything, you might as well just roll over.’ [But] I was really annoyed with it, that it was going to stop me seeing my family, actually kill me. You think to yourself you [will die] unless you try and work out how you are going to get out of this. I managed to slow [my breathing] down, checked my gear was OK, keeping an eye on the shark. Still had plenty of air. It went away into the gloom. I had a rough idea where I’d seen it disappear. Next thing it came flying across the reef at me. I had my spear gun and I thought I could shoot it but then it’s just going to get annoyed and crazier. I saw it come in and out of the gloom. Then it charged. It ran me down like a car. It was like a dart. The distance would have been 15 to 20 metres and it covered that in a couple of seconds. I had just enough time to lift my spear gun and try to fend it off. It went straight over my head. It would have been one metre above me. The girth of the thing. Like a car going over. Massive. Absolutely massive.

The speed of the shark as it bit down on Williams’ elbow and vigorously shook him created an unusual wound – saltwater forced into the bite area at high pressure had a gouging effect, but he didn’t become aware of the pain until he realised the shark’s tactics had moved him further away from the reef and out on to the sand. Returning to the cover of the reef ledge, he noticed he was bleeding badly and visibility was diminishing.

Blood was making the water shimmery. At that stage I was feeling woozy, beginning to fade. The shark charged again. It [got to] within a couple of metres and all of a sudden it did a shimmy in the water, turned its tail and took off. The speed of the thing!

Assuming the animal had disappeared and would soon make another run at him, Williams turned in anticipation, to see his two dive friends swimming quickly, elbow to elbow, across the reef. With Jenny signalling that she had just seen a giant shark, it was soon clear that the pair had arrived with Jenny’s shark shield just in time. Bernie believes the abrupt shift in the shark’s behaviour and swimming direction as it homed in for another strike signalled its clear discomfort once inside the orbit of the approaching shield.

He believes his friends may not have returned to find him for another 10 minutes had they not seen the shark, as both had plenty of air in their tanks. By the time the three pulled themselves to the safety of the boat just a couple of minutes later, Bernie’s own tank was almost empty.

How humans react

Research has shown that sharks maintain a pattern of “temporary residency” at favoured sites along with periods of long-distance travel using some “common corridors”. They do not permanently stay at any one site but are more likely to be present at favoured places and in common corridors. The fact that they don’t give birth until they reach about 5m in length and 16 years of age, and have an 18-month gestation period, make the sharks “vulnerable to even low levels of exploitation (including incidental bycatch) and are slow to recover”, according to the Commonwealth Scientific and Industrial Research Organisation (CSIRO).

It is also now clear that Australia has two distinct great white shark populations; an eastern population and a western-southern population. In other words, the 2.6m great white shark that injured a surfer at Ballina, on Australia’s east coast, in November 2018 probably belonged to a different – and considerably smaller – population than the animal (or animals) that attacked surfers in April in Margaret River.

Back in 2007 one of the world’s foremost white shark experts, Dr Barry Bruce, told me that anyone who thought they knew how many white sharks were cruising Australian waters was “speaking through their backside”.

A surfer in the water despite shark warning signs posted on the beach in the NSW city of Newcastle. Photograph: Peter Parks/AFP/Getty Images

In February Bruce co-published an article in the journal Scientific Reports about a groundbreaking CSIRO study that used world-first genetic analysis to estimate that there are between about 760 and 2,250 adult white sharks (best estimate 1,460 sharks) in the southern-western population off South Australia and WA, and between about 470 and 1,030 adult white sharks off eastern Australia (best estimate 750 sharks).

The total white shark population off eastern Australia was estimated to be between 2,909 and 12,802 sharks (best estimate 5,460 sharks). Due to a lack of genetic data for juveniles, the total number of the southern-western population could not be directly estimated using these techniques.

There are double the number of adult white sharks in the WA-South Australia population and fewer surfers, swimmers and divers (4.1 million people) compared with the east coast (18.8 million). And yet, since 2000, the western population has been responsible for 21 fatalities compared with the east coast’s five.

Shark nets have been used for decades on the east coast of Australia, with mixed success. But the problem of unintended bycatch, including dolphins and turtles, puts them out of favour in WA. Certainly, there is no silver bullet.

A newly appointed independent scientific advisory panel on sharks will provide advice to the WA government on the effectiveness of its new shark mitigation technologies and scientific research into white shark populations, movements and behaviours.

The lead author of a University of Queensland study a that shows 90% decline in Queensland shark numbers says more advanced approaches to safeguarding ocean users are needed. Dr George Roff says drum lines, nets and culls are not the answer.

“Nets do not stop sharks from entering beaches, but instead are designed to entangle and trap sharks [and] there is no scientific evidence that I am aware of that shows that culling is an effective approach to reducing shark attacks,” he says.

A dead great hammerhead shark found caught in a shark net off a beach on Queensland’s Gold Coast Photograph: Sea Shepherd Australia/EPA

“Smart drum lines are good for understanding where sharks go and if a certain shark tends to return to the same beach, but white sharks often travel hundreds to thousands of kilometres. For smart drum lines to be successful they have to tag a large number of sharks within the population.

“Modern technologies such as camera-mounted drones can monitor beaches for sharks in real time, and Sharksafe barriers trialled in South Africa show that white sharks can be successfully excluded from swimming areas.”

Q&A How to reduce the chances of a shark encounter outside patrolled beaches Show Wear a personal shark deterrent.

Stay close to shore and avoid deep channels or areas near steep drop-offs.

Never swim in places where human or animal waste enters the water.

Avoid disposing of fish waste near swimming beaches and don’t remain in the water with bleeding wounds.

If spearfishing, don’t carry dead or bleeding fish attached to you and be sure to remove all speared fish from the water quickly.

Avoid large schools of fish, seals or wildlife behaving erratically.

Stay informed about current whale-carcass and shark sightings (in WA, that means checking the shark activity map and the Surf Life Saving WA Twitter feed.)

White Wharton beach in Cape Le Grand national park, Western Australia. Photograph: Alexander Ludwig/Alamy Stock Photo

‘A full-on horizontal attack’

Just 11 months on and about 700km away from where Bernie Williams was attacked, 15-year-old Zac Golebiowski was enjoying a morning’s surf at a remote beach on Australia’s south coast when his life was irrevocably changed.

In a nation renowned for its picturesque coastline, Esperance beaches represent some of the most “grammable” of all. With bay after bay of blinding white sand and clear cerulean waters, this part of the world could have been enhanced by a Technicolor enthusiast’s sleight of hand.

But on the morning of 2 December 2006, a bruise of clouds hung low over Esperance and a bitter south-easterly wind soured surf conditions. Golebiowski was eager for a surf, nonetheless. So he headed out by car with older brother Sam and a teenage friend to a protected cove they knew would be breaking clean and perfect.

Nestled between two national parks, Wharton beach, on Duke of Orleans Bay, is a favourite with families for its long and easy sandbar breaks close to shore.

It was overcast and gloomy, a ‘sharky’ morning, but sharks [were] the last thing to think about when you are 15 and going for a surf with your brother and a mate. I had never heard about sharks at Whartons – it is the last thing, the very last thing, I expected.

The sandbar was so shallow that, after each ride, it was impossible to turn and duck his long malibu surfboard under oncoming sets. Instead, Golebiowski rode each wave into shore, walked the length of the beach and then paddled out for the next ride.

Zac Golebiowski. Photograph: David Dare Parker

[After] three or four waves I got one that was a bit of a dud. It didn’t quite take me all the way into the beach. I started to paddle back out to where my brother was. The shark came in from deeper water and took my right leg as I was paddling towards [him]. It came from the side and it felt like what’d you’d imagine a big king hit to be like. A very big strike. It was a full-on horizontal attack in water that was only just head height. When I take my friends to where the attack happened they are always amazed that a shark attack could have happened there. The shark bit [off] my leg and the force of the bite took me down, pulled me under. There was no fighting for air. It was too shallow for that. It took me under and let go. I came straight back up and called for help. The [2.5-metre to three-metre) shark was probably a juvenile, curious, experimenting maybe. If it had been bigger it would have bitten me in half. A big shark in full hunting mode, it would have been carnage. [My brother] said it circled a couple of times. It could have attacked two more people but didn’t. Any higher up my leg and it would have got [major] arteries.

Golebiowski’s survival was enabled by the quick and decisive action of his brother and strangers on the beach. Despite his trauma, the ocean continues to draw him in. No longer able to stand on a surfboard, he now uses a boogie board.

It’s generally pretty good. I just think about the chances of a shark coming back and attacking a person again – it is never going to happen. But surfing at Whartons is a whole other ballgame. In the last few years with so many attacks I have thought about [the attack] more. It is coming up to 12 years since it happened. I [don’t] feel comfortable out there at all.

Zac Golebiowski.

There were eight WA shark fatalities in almost as many years after Golebiowski’s ordeal. On 2 October 2014 Sean Pollard, then 23, narrowly escaped becoming the ninth when he suffered a devastating attack by two great white sharks at the Esperance surf break where two and a half years later, in April 2017, 17-year-old Laeticia Brouwer became the state’s most recent shark attack victim.

Pollard lost his left arm and right hand, and ligaments in both legs were damaged when a shark made three ferocious strikes, as the former electrician attempted to fend it off with his surfboard. In 2015 he told 60 Minutes:

I felt this massive bump and the shark came underneath me. I was trying to paddle calmly so I wasn’t splashing around like I was panicking, but once it got directly behind me it charged. Went in for the kill. Both my arms were in its mouth, its eye was right there. That vision – this cover going over its eye as it bit down on me – [is] burnt into my mind. It took me underwater, started shaking its head. I remember having to hold my breath and it shook seven or eight times. That’s when I got bumped from behind by another shark.

Back on the surface and with both hands now severed, he lay on his back and kicked for his life, catching a wave back into shore, where decisive action by four bystanders almost certainly saved his life.

‘It shook me violently’

Almost a year after Pollard survived this attack, a free diver and spear fisher Norman Galli, then 50, dropped into a glassy sea off a small island near Albany, a five-hour drive further south. The environmental manager from Perth and his regular dive partner, Anton Van Zyl, had been in the water all morning spearing about a dozen fish when Galli felt the impact of what he initially thought must have been the hull or motor of a speeding boat.

I was right up along a ledge that went from two metres depth down to five metres. I actually thought that the boat had driven over me – that is how hard and sudden the impact was. And how quickly it was over. I was blindsided.

Norman Galli at Cottesloe beach. Photograph: David Dare Parker

He had twice before encountered great white sharks in the ocean at close range. In both instances – in South Africa in 2000 and near Moore River on WA’s mid-west coast in 2012 – the animals departed as quickly as they appeared.

But this time it was a different story.

Experienced spear fishers say the shark that is going to bite you is the one you don’t see, and I certainly didn’t see this shark at all. It came in at a 45-degree angle from behind and attacked very close to the surface. The impact was hard, brutal. I was shaken around like a rag doll. It was just ferocious.

And, were it not for the spear gun he was carrying, his life may well have ended there and then, on 30 October 2015. Like Allan Oppert and Bernie Williams, Norman Galli believes that the steel implement saved his life. In the first moment of the attack, the gun was rammed hard up against his ribcage. He believes its barrel became stuck in the back of the shark’s jaw.

The town of Albany was a whaling port until 1978, when ships carrying harpooned whales would attract hungry white sharks in their wake. There have been several shark attacks in the area in recent years, including the fatal mauling of the 17-year-old spear fisher and free diver Jay Muscat nine months before Norman Galli’s close call, and in the same stretch of water.

Free divers descend for minutes at a time on a single breath of air – held for long enough to locate and harpoon a fish, and return to the surface, which is where Galli was floating at the time of the attack.

It shook me violently and I felt the cut of a tooth in my stomach. There was just a lot of white water and foam. When it released me and the commotion stopped I lifted my head out of the water, expecting to see the boat on top of me, but it was in the same position 150 metres or so away. I shouted for Anton. I backed up into a two-metre-deep rock ledge with my back towards Bald Island, feeling very vulnerable without my spear gun, which I could see about 20 metres away. Anton had parked the boat a safe distance from the swell and surge, which was crashing in to the island, and he called me to the boat. The island is surrounded by tall granite cliffs so I couldn’t get out of the water. I had to swim 30 metres or so. I didn’t know what had happened until I climbed on to the boat and blood was dripping from my stomach. When I lifted my arm, there were teethmarks in the wetsuit.

It is difficult to tell whether any of the attacks described here might have been prevented by the mitigation strategies now in place in WA. Even if the shark that attacked Golebiowski in Esperance had been tagged, there were no receivers at the remote beach and, even if there had been, who knows whether an alert would have reached him in time. The same could be said of Galli and Pollard.

Zac Golebiowski with his boogie board. Photograph: David Dare Parker

But for surfers and divers in particular, shark shields are recognised as potent protection. Among the suite of measures designed to keep ocean users safer, the WA government has introduced a rebate for approved shields, the first such initiative in the world. So far, 2,300 regular ocean users have taken up the offer, embedding them in surfboards or wearing them on ankles.

In the meantime, a number of attacks on Australia’s east coast in recent months will be in the thoughts of many ocean users across the country this summer. But only time will tell whether government measures can take a bite out of WA’s formidable reputation as a global shark-attack hotspot.

• Fiona Adolph is writing a book about shark attacks in Western Australian in the past 20 years