For nearly two decades, Carbrook Golf Club near Brisbane, Australia, had its biggest water hazard: a pond full of bulls.

It all started in 1996 when floods swept six baby sharks from a nearby river into a 51-acre lake near the 14th hole of the golf course. When the flood waters recede, the sharks find themselves stranded, surrounded by grassy hills and eager golfers.

The sharks spent 17 years in the lake, living on a diet of large fish and occasional meat given to them by the organization’s staff. One shark was caught illegally, while others disappeared after the floods that followed.

Sharks, according to a new study, are more than just chilling on the side of the road. In a study published last month in the journal Marine and Fisheries Science, Peter Gausmann, a shark scientist and lecturer at the Ruhr University in Bochum in Germany, said that members of the Carbrook bull sharks club showed that bull sharks can live indefinitely in low salinity waters. surrounding areas.

Bull sharks are found in warm coastal waters around the world. These powerful sharks can reach 11 to 13 feet in length and weigh over 500 pounds. They are one of the few shark species that can tolerate a wide range of salinity, a trait that allows them to enter freshwater and brackish habitats such as rivers, estuaries and estuaries.

Unfortunately, this attractive adaptation often puts sharks in close proximity to humans, one of the many reasons why bull sharks are responsible for many human attacks.

If too many sharks were to enter freshwater, their internal salt would dissolve and they would die. But male sharks have specially adapted kidneys and glands that work together to recycle and store salt in their bodies.

Clean water and brackish habitats give small sharks a place to grow without the threat of larger shark attacks. Once they reach maturity, however, bull sharks tend to go to the ocean, where there are bigger prey and more breeding opportunities. That the Carbrook shark population did not increase during their time on the golf course provided further evidence that the species prefers to spawn in saltwater areas.

While scientists have long known that bull sharks have ways to travel between cooler and salt water, no one knew that these sharks could spend their entire lives in fresh water.

Research suggests bull sharks can live up to 30 years, and Carbrook’s group survived in a golf course pool for 17 years. That suggests there is no “upper limit” to how long these sharks can spend in low-salinity environments, said Vincent Raoult, a postdoctoral researcher at Deakin University in Australia who was not involved in the new study.

“I think a lot of people might be scared to learn that there might be bull sharks in their local pond, but the truth is, it’s amazing that there are animals that can do this,” said Dr. Raoult.

While the idea of ​​sharing a lake with bulls may be intimidating to some, golfers are taking advantage, Scott Wagstaff, general manager of Carbrook Golf Club, said.

“Every member here loves sharks,” said Mr. Wagstaff.

When the sharks were still alive, he and other workers would throw pieces of meat into the water and marvel at how the sharks ate their gruesome meat. “I’ve seen them jump out of the water and spin around as they come down. It was cool,” said Mr. Wagstaff.

Extreme floods like the one that washed sharks in and out of the Carbrook Golf Club are becoming more common, and many bull sharks can end up trapped in lakes, ponds and lakes. Although you’re unlikely to encounter a bull shark at your local swimming hole, Dr. Gausmann advises avoiding large bodies of water that have recently been affected by flooding.

“Never bathe in stagnant water that used to be connected to the sea. You’d never know there were sharks living there,” he said, although urban dwellers may not worry, as urban flood waters are often too toxic to sustain marine life.

And there is another lesson to be learned, as shark sightings and occasional human attacks cause fear in some areas.

“If this paper shows anything, it’s possible to live with sharks,” said Leonardo Guida, a shark scientist with the Australian Marine Conservation Society.