On May 13, 2018, British fisherman Mark Berryman, 21, was taken to hospital with “four or five significant cuts below his knee”, inflicted by a porbeagle shark – a species of mackerel shark native to the temperate waters of the North Atlantic and Southern Hemispheres. The porbeagle shark can grow up to 2.5 metres in length, and is one of the most common sharks encountered by fishermen around the British Isles.

The wounds this particular shark inflicted on Berryman penetrated down to the muscle, but were not life-threatening. Usually, the porbeagle shark – like almost every other species of shark – goes out of its way to avoid humans, and attacks are rare. The difference here is that the shark was caught in a fishing net belonging to Berryman and his crew, and the attack happened on board the ship, instead of the ocean. Arguably, then, the attack wasn't a mauling by a predator, and more of a survival attempt by a trapped and desperate animal.

According to the Florida Museum, in 2017 there were 88 unprovoked attacks by sharks on humans, and five fatalities, making it an “average year” for shark-human interaction. Meanwhile, a 2013 report published in the journal Marine Policy estimated that anywhere between 63 million and 273 million sharks are killed by humans each year. Off the back of this report, it has been estimated that 11,417 sharks are killed by humans per hour, year in, year out – many in the illegal pursuit of their fins, most as a “bycatch” of commercial fishing vessels – like the porbeagle that attacked Berryman.


Yet not all shark deaths are for commercial gain. From December 2014 to March 2017, the government of Western Australia implemented the ‘Western Australia Shark Cull’ after seven human deaths between 2010 and 2013. During the cull, 72 drum lines were set in the ocean to hook sharks. The project cost a reported $20 million Australian dollars and led to riots across the state between government and civilians opposing the cull.

It’s clear, then, that as a species, humans have a shark problem. But, for one enterprising observer, the Western Australia Shark Cull provided something of an epiphany. The events of that Australian summer would set then 56-year-old UK native Collin Brooker on a path that would see him sell his Cardiff-based businesses, re-mortgage his house, rekindle his relationship with his adult son, and sink everything he had into finding a way for humans and sharks to co-exist in harmony. Now, after four years of development, Brooker believes he has landed on an elegant solution that will keep humans, sharks and their shared ecosystem intact, without the need for a single death – only the scent of it.

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Podi has been created by Colin Brooker and his son Simon. The device releases an artificial smell of sharks that helps keep sharks at bay Podi

Born in Kokstad a small town in the Harry Gwala District Municipality of South Africa to English parents in 1957, Brooker learned to speak Zulu before he could speak English. His family relocated to Kent, UK in 1966, when Brooker was nine-years-old. Later an electrical engineer by trade, Brooker also set up a landscaping business in Australia, where he lived from 2014-2017. He has also owned and operated a coffee shop and restaurant in Cardiff, with his 27-year old son Simon. There’s little in this nomadic background to suggest that Brooker would potentially succeed where many trained scientists and national governments have floundered. Apart from, that is, his ability to latch onto a subject, and refuse to let go.


“I was really pissed off at the authorities,” Brooker says, speaking about the 2014 protests that erupted across Brisbane and Western Australia when the Western Australia Shark Cull was implemented, and which Brooker witnessed first hand. The policy was to cull sharks of over 3.5 metres, and as the majority of sharks in that area are in excess of four metres, Brooker saw this as a general attack on the entire species. “I thought, ‘’We’re the most intelligent species on the planet, there has to be a better way of resolving this conflict,’” he says.

Hoping that if sharks could be persuaded to leave humans alone, such measures would no longer be necessary, Brooker put his thinking cap on, and he and Simon sold their stakes in their Cardiff properties and sank everything into developing the Podi. The device, which can be attached to a surfboard or worn on the person that slowly, releases a chemical based on the scent of dead shark. This chemical continuously dissolves in water, providing a potent, and potentially life-saving, repellent. With Podi, the Brookers’ aim is to prevent sharks from wrongly being killed, while also preserving reefs and wider marine ecology.

As well as £250,000 of their own money, (and to date, zero input from outside investment) the scheme would take over the lives of both Brooker and his son. Having reunited just a few years earlier following a long-distance relationship, going all in on his father’s scheme was far from an easy sell for Simon.

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“[Dad] returned from Australia, sat me down and pitched this crazy idea to me,” explains Simon, who has a bachelor’s degree in fine art from Cardiff University. “It took me quite a while to take it all in. I’d never left the UK. To go on this adventure around the world in order to save and study sharks was quite daunting.”


Yet his father’s tenacity won in the end. Brooker admits that he “knew nothing of sharks, or science” yet he did what anyone would do in his position: he took to Google. A comprehensive trawl of the internet told Brooker that not only were most current shark defence systems expensive, the majority only worked in close-proximity, a range which Brooker believes is too dangerous. Or, as he puts it “Not even a double-barrelled shotgun will stop a white shark when it’s a metre and a half away in attack mode.”

Brooker sought a more logical approach, beginning with the assumption that, like every animal in existence, a shark can be persuaded to flee as an act of self-preservation. The key to encouraging such behaviour was stimulating its most powerful sense. Many sharks can detect their prey at one particle of DNA in 10 billion, while a white shark can smell prey up to 1.8 miles away. Using a shark’s own sense of smell against it, it seemed, was the answer.

“I thought if we can make a smell that it doesn’t like that encourages it to move on, we’d have something. Sharks generally aren’t cannibalistic, so I thought a rotten shark might just scare another shark,” says Brooker. A delivery of shark guts was en route from a local fishmonger when Brooker happened across a BBC documentary outlining the work of Eric Stroud, an American chemist who had discovered that the essence of dead shark is in fact able to repel all shark species, as well as some species of ray, but, usefully, not other fish.

Believing Stroud to have beaten him to it, Brooker worried that his idea was dead in the water. Eventually, however, he realised that Stroud’s product – a manually-activated device similar to an aerosol can and sold under the name SharkTec – had the same problems as the other shark repellents on the market. Namely, that a shark would need to be in blinking distance before the device could be used effectively. In other words, it would require a swimmer or surfer to be on the lookout for sharks at all times if they are to stand a chance of activating it in time.

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A chemical based on the scent of dead shark is released from the Podi. The smell deters sharks Podi

The use of dead sharks to repel live sharks isn’t anything new. For hundreds of years fishermen in the Indian Ocean have been towing dead sharks behind their boats to protect their catch. Naturally, though, with shark preservation as its aim, Podi could not use actual dead shark. “It doesn’t make sense to kill a shark to protect yourself against one,” Brooker says.

To circumvent this problem, the Brookers enlisted the help of Cardiff-based pharmaceutical company CatSci. The company began by chemically mining a shark sample and mapping 60 possible chemical components responsible for the off-putting scent. It then narrowed this down to a possible six chemicals. The Brookers then recruited divers to help them test each of the six compounds in Fish Hook bay, on South Africa’s Western Cape. The Brooker’s chose the spot carefully; close to a surfing beach, a rocky outcrop formed a natural funnel through which juvenile bull sharks would swim.

To test the compounds, divers swam out to baited areas, then released the solutions into the water. On the second of six attempts, there was not a shark to be seen for a full five minutes. Best of all, other fish were unaffected, and the sharks were able to return once the solution had been dispersed, meaning the ecosystem was free to continue as it should, with only a minor interruption. The Brookers had found their compound.

Now they have identified their product, the Brookers are investigating the best dosage to use, and the optimum rate of dispersion so that a swimmer has sufficient protection for as long as possible. Ideally, the Podi solution will provide a safe space with a 500m radius. This also raises the question of how best to deliver the solution. Dissolvable tablets, Brooker decided, were not saleable, so instead they have begun to look at dissolvable, eco-friendly plastics that can be attached to a surf leash, or tied around a swimmer’s ankle. 3D printing may well be the solution to this, with the Brooker’s currently exploring the possibility of printing their compound directly onto materials to make wristbands or even life vests for airlines.

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As well as personal protection, the Brookers believe the Podi will have huge applications for coastal defence, search and rescue, and national shark policies. It’s an ambitious claim, but one that is already beginning to bear fruit. As the result of Brooker’s tenacious email campaign, the government of Reunion Island in the Pacific Ocean have shown interest in the Podi and invited the Brookers’ to meet with it.

It is here, perhaps more so than anywhere else in the world, that the balance between humans and sharks has swung wildly out of hand. Last February, 26-year-old Alexandre Naussac became the eighth person to be killed in a shark attack on Reunion Island since 2011. Meanwhile, in August 2016 a 21-year-old lost his arm and foot in a shark attack. According to the International Shark Attack File, Reunion Island was responsible for over 16 per cent of the world’s shark attacks between 2011 and 2016. In response, surfer Kelly Slater called for a ‘serious cull’ of bull and tiger sharks on the island, while authorities put a ban on surfing and swimming – a state of affairs that has seriously impacted tourism – the lifeblood of the island.

“There’s a sense of despair on the island because people’s livelihoods have disappeared,” says Brooker. “At first [the government] didn’t want to talk to us because they thought we were crazy, but they’ve been running tests over the last year on existing repellent devices, and I was approached about three months ago to go and assist them. We’re hoping to go and work with the scientists there by the end of 2018. I believe we can cure the problem inside two years.”


Michaël Hoarau from the Reunion Shark Risk Management Centre (CRA) – a joint enterprise between the French government, the provincial government of Reunion, and the University of La Reunion – confirmed its communication with Brooker. One of the missions of the CRA is to promote methods reconciling the interests of beach users and the conservation of marine biology. As such, the CRA will independently test the Podi, alongside other innovative possible solutions including drone, sonar, physical barriers, and other repellent devices.

Brooker believes the Podi is just 18 months away from completion. Once a method of delivery has been agreed upon, Simon explains, the company will begin pursuing outside investment – although the Brookers hope at first to distribute the product through their surf brand, SeaDog. From there, any local authority with over-zealous sharks in its waters is sure to find Brooker’s name popping up in its inbox.

“We ran a cafe a year ago. Now we’re telling the French authorities how to do things,” says Brooker. “We’ve spent £250,000 so far. It’s come from selling our business in the UK, my private pensions and sale of the house… we’ve put our lives on hold. We’re risking everything.” With the Podi, set to launch in the near future, the question now is will it sink, or swim?