Six bull sharks inadvertently made their home on an Australian golf course. Then they vanished

By Jack Bantock, CNN

(CNN) — For golfers, staying out of the water could be the difference between winning and losing. At one course in Australia, it was the difference between life and death.

Because Carbrook in Queensland boasted a membership unlike any other golf club on the planet: six resident bull sharks.

From their mysterious arrival to their devastating disappearance 17 years later, this is the tale of the sport’s most hazardous water hazard.

Arrival

A lake on a landlocked golf course some 14 kilometers (8.7 miles) from the Pacific Ocean may sound like a swim too far for any fish, but the bull shark has a reputation for dipping its fins into a range of habitats.

River shark, freshwater whaler, estuary whaler, swan river whaler – the clue is in its other names. While native to warm and tropical waters worldwide, bull sharks have organs specially adapted to retain salt, allowing them to venture deep into freshwater environments that would prove fatal to other sharks due to a loss of sodium.

Hence the presence of the stocky-built, blunt-nosed sharks in the Logan River – which slices inland from the sea halfway between Brisbane and Gold Coast before meandering around Carbrook golf club – came as no real surprise to locals in the 1990s.

Neither did severe flooding.

Twinned with the region’s subtropical climate, the club has been a hotspot for floods since its inception in 1978, inundated with water on numerous occasions including in 1991, 1995 and 1996.

The downpours were so torrential that on the latter three occasions, the roughly 100-meter land bridge separating the river from the sand-mine-turned-lake beside the course’s 14th hole was totally submerged. A new corridor was opened and – sometime during those three temporary windows – six bull sharks glided into uncharted waters.

As the land bridge dried and reformed, the door slammed shut behind them. It would remain closed for 17 years, when the next severe flood event reforged a path to the river in 2013.

Carbrook’s Nessie

Towards the end of the century, whispers began to trickle around Carbrook’s fairways – all originating from the 14th green.

There were reports of loud splashes, large dark shapes moving below the lake’s surface, even laughed-off claims of a tall dorsal fin knifing through the water. “The Carbrook Shark” became a kind of folk legend, Australia’s own Bigfoot, Yeti or – most similarly of all – a local version of another famous lake-dwelling mythical beast.

“The Loch Ness monster is pretty similar to what it felt like,” Carbrook general manager Scott Wagstaff told CNN.

“It seemed possible but there wasn’t enough truth to it at that point.”

That was until the early 2000s, when the Brisbane-based Courier Mail turned folklore into fact by publishing a picture of one of the sharks, Wagstaff recalled. Yet despite having played at the club for years, he had never seen them with his own eyes when he started work there in 2010.

Determined to satisfy his curiosity, Wagstaff ventured down to the lake armed with his camera and some meat. No sooner had the bait hit the surface, a shark duly appeared.

The stunned Wagstaff snapped some shots before taking a short video on his phone to post online. The footage was – by his own admission – “terrible,” but the internet lapped it up: the viral YouTube video has amassed more than 2.3 million views to date.

Media interest boomed, and the club embraced its toothy tenants with vigor.

A bull shark was added to the club’s logo, its youth program was named the Junior Shark Academy, and feedings were held at tournaments and corporate events – including one special wedding in 2009 where all six sharks appeared at once, Wagstaff recalls.

Despite his affection for the sharks, Wagstaff was reluctant to call them pets, though he did nickname one “Patch,” thanks to its distinct back marking.

Compared to the crocodiles and snakes dotting other courses in the country, Carbrook’s sharks made for extremely low-maintenance residents. Only two risk-management steps were taken: warning signage around the lake, and the rejection of any business from prospective golf ball divers, who retrieve balls from course lakes to sell them on.

“It’s just not worth the few grand a year we get for a contract to put someone’s life at risk,” Wagstaff said.

Unprecedented

Fascination spread far beyond Australian borders, piquing the interest of one shark-loving scientist and researcher based at Ruhr University Bochum in Germany.

Dr. Peter Gausmann published his study on the Carbrook sharks, titled “Who’s the biggest fish in the pond?” in the Marine and Fishery Sciences journal in August 2023. Their extended residence, he argued, sheds new light on just how adaptable bull sharks are.

Even without the staff feeding the sharks, hunger was not a cause for concern in a lake 700 meters long, 380 meters wide and 15 meters deep, teeming with fish, from mullets to tarpons and snappers.

Gausmann calculated that the sharks would need to consume half a ton of fish per year – or 0.44% of their body weight per day – to meet their energy needs. Having been juveniles when they arrived, sightings verified they had grown to a healthy range of between 1.8 and 3 meters by 2013.

Only twice before had bull sharks been recorded surviving for years in isolated bodies of water, according to Gausmann, yet none had ever lasted so long.

One group made it at least four years in Panama’s freshwater Lake Bayano in the 1980s, while another survived a decade of high salinity in South Africa’s Lake St. Lucia after becoming trapped in 2002.

A stay of at least 17 years in low-salinity waters — more than half a bull shark’s lifespan — was unprecedented.

“This out of the ordinary occurrence has shown verifiably for the first time how long bull sharks are able to survive in these low-salinity environments,” Gausmann told CNN.

“The study has shown that bull sharks presumably have no limits to their residential time in freshwater environments such as lakes and rivers, and they are presumably – at least theoretically – able to spend their entire lifetime in these habitats.”

Vanished

Sadly for Gausmann and Carbrook, the true extent of their survivability remains unknown.

It’s been eight years since a shark was last spotted in the lake. Their vanishing is a mystery, even to Gausmann.

Sightings dropped in frequency after the 2013 floods, leading to fears that some sharks may have returned to the river or died as a result of the storm. Just two sharks were confirmed dead; one found floating on the surface, another killed by illegal fishing.

Wagstaff, who had never noticed any sign of ill health among the sharks in more than 100 sightings, saw them only fleetingly after the fishing death. Gausmann believes it was unlikely the remaining sharks died in a “natural way” due to sodium loss or by any other “anatomical” failure, given their adaptability, and therefore theorizes that further illegal fishing is the “most likely” explanation for their disappearance.

Whatever the reason, it’s an absence felt keenly by the club.

“You can’t help yourself – you walk along the lake and you’re looking in, waiting to maybe catch a glimpse of a fin breaking the water,” Wagstaff said.

“The members loved the fact that their golf course was their unique place in the world where we had sharks; they just embraced it.

“We’d love to see them again.”

Last year, the course was submerged by the biggest flood ever recorded in the area, Wagstaff said. Though devastating financially, closing the club for two months, it sparked hope that new sharks may have crossed from the river to repopulate the lake.

Only time will tell, but Carbrook is already planning for a future without its mascot. Plans are in place to fill in the lake and build a new course there over the next decade, with all marine life – potential sharks included – subsequently relocated into waters elsewhere.

Whether Wagstaff ever spots another fin in the lake or not, he will remember “Patch” and co. fondly as the guests who helped him overcome his fears. Once afraid of the ocean due to sharks, Wagstaff recently went scuba diving in the reefs of the Sunshine Coast to get up close and personal with some large grey nurse sharks.

“There’s this kind of legend about sharks being aggressive because they’re coming into contact with humans, especially bull sharks because of the places they tend to swim – canals, creeks and rivers,” Wagstaff said.

“But then to experience them in such close proximity and see how beautiful they are and how graceful they are – now I just find them fascinating, especially the bull shark.

“They’re capable, so adaptive, and they are seriously beautiful when you’re a few feet away. It’s an incredible shark.”

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