A group of bull sharks lived in a golf-course pond for 17 years. Scientists say they could be in other ponds in Australia.

• A group of bull sharks lived in a freshwater golf-course pond for more than 17 years.
• Scientists say it's the longest they've ever seen sharks live in freshwater.

For almost two decades, a golf course in Australia boasted a unique selling point — a shark-infested pond near its fourteenth hole.

Bull sharks in a pond are odd enough. Sharks in a golf-course pond are odder still. But this group of bull sharks is even odder.

It's somewhat of a scientific marvel because the sharks have lived in fresh water longer than any other group of bull sharks that scientists have observed.

Groups of bull sharks have been trapped in freshwater areas in Panama and South Africa, but those groups lasted about four years, Melissa Cristina Márquez, a marine biologist who wasn't involved in the study, reported in Forbes.

A recent study concluded bull sharks could survive in fresh and brackish water for long periods, shown by the bull sharks that lived in the golf-course pond for an estimated 17 years — more than half of bull sharks' projected 30-year life span.

"This new publication highlights their impressive adaptability to a wide variety of environments," Amy Smoothey, a shark scientist who wasn't involved in the study, told Slate.

How the sharks ended up on a golf course

In the mid-1990s, three severe floods pushed six juvenile bull sharks from nearby rivers into the golf course's pond. When the flood waters receded, the sharks were left stranded.

Bull sharks usually spend their early lives in the brackish waters between a river and the ocean, hiding out from larger saltwater predators. They typically head into the sea at about five years of age, the study says. Or, in the event of a flood, they can end up stranded in ponds like this group.

Besides tossing the occasional scrap into the water to catch a look at the fish, the golf course left the bull sharks alone. They were never tagged.

The club did, however, make the sharks its mascot and logo.

Where are the bull sharks now?

Since the sharks were never tagged, what scientists know about the health and current whereabouts of the first sharks comes from word of mouth.

They know one shark was illegally hunted, and another turned up dead from natural causes, but the study said the others could have died or escaped over the years, especially during a series of floods in 2013.

The last time any shark was spotted in the pond was in 2015, but the scientists aren't sure if that was from the original group or not.

Watch out for stagnant bodies of water

"I think a lot of people would be scared to learn there could be bull sharks in their local pond, but the fact is, it's pretty amazing that there are animals that are able to do this," Vincent Raoult, a marine ecologist at Deakin University in Australia who wasn't involved in the study, told the New York Times.

When bull sharks usually make the headlines, it's for their attacks on humans. This species comes in third place for the most attacks on humans, trailing behind great white and tiger sharks.

As extreme floods become more common and severe with the climate crisis, it's important to be wary of bodies of water that may have recently flooded, especially in areas with bull sharks.

Even though it's unlikely that a shark will be in your favorite pond, "you should never bathe in stagnant bodies of water that once had a connection to the sea. You never know if sharks are living there," Peter Gausmann, a shark scientist, told the NYT.