By ANNA USHER

Balmoral Beach has been chosen as the site of a new shark-detection buoy, boosting swimmer safety in Mosman.

The NSW Government has identified Balmoral as a preferred location for one of two new shark detection buoys to be placed in Sydney Harbour, with the second earmarked for the Sow and Pigs reef near Camp Cove Beach in the eastern suburbs.

The devices, which are not visible from the beach, detect electronic signals – known as “pings” – emitted by sharks that have been tagged for monitoring. These signals trigger real-time alerts to users of the SharkSmart app when a tagged shark comes within 500 metres.

The announcement follows several shark attacks in Sydney in January; four people were bitten or narrowly avoided injury in 48 hours – including one fatal incident involving a 12-year-old off Vaucluse after entering the harbour water.

Marcel Green, head of the NSW Government’s shark management program, said both locations were chosen because sharks are known to pass through them.

“The main focus is trying to look at those beaches that are used down in the lower parts of the estuary, such as those at Vaucluse and Nielsen Park, and also over there at Balmoral Beach,” Mr Green told the ABC.

There are already 37 listening stations – specialised underwater sensors that detect tagged sharks, along the NSW coast, from Tweed Heads to Merimbula, but until now, none have been placed inside Sydney Harbour.

The critical caveat: the system can only detect sharks that have been electronically tagged with special transmitters. If a shark does not have a tag or if its transmitter battery has died, it will not be detected.

“You’ll never be able to tag every shark that swims in the ocean,” Mr Green said. “But we’re pretty confident that we’re going to have a really good handle on it over the next couple of years.”

WATCH: Underwater tour of shark listening station.

Since late January, scientists have tagged four bull sharks inside Sydney Harbour and 18 in Coffs Harbour as part of the expanded program.

Mr Green said the listening network would give scientists a vital early-warning system as sharks move through the harbour, including through Middle Harbour, the waterway that runs inland past the Spit Bridge.

“As these animals move into the harbour, both into the southern part and up into the Lane Cove [River] through Middle Harbour, we’re then going to have a bit of a canary in the coal mine,” he said.

The January attacks followed a period of heavy rain, which produced brackish (a mix of salt and fresh water) conditions, which favoured bull sharks.

Bull sharks are currently leaving the harbour as the water cools. Tagging is expected to resume later in the year.

Mosman Mayor Ann Marie Kimber told Mosman Collective that the open waters of Balmoral – including shark management – fall under NSW Government jurisdiction, not the Council’s.

“We welcome the Government’s focus on helping people make informed choices about swimming in open water,” Mayor Kimber said.

The Mayor also flagged a notable crossover: Associate Professor Chris Pepin-Neff from the University of Sydney has been involved in the government’s shark work and is separately engaged by Mosman Council as a specialist in its own shark risk mitigation strategy -specifically for areas Council manages, including the Balmoral Baths.

Cr Kimber’s advice to swimmers was practical: avoid the water after heavy rain or when baitfish (small fish that attract larger predators) are active, and stay aware of conditions at all times.

When will it happen?

The preferred locations for both devices are still awaiting official approval and are expected to be placed in the water within the next few months.

Mr Green’s own advice echoed the Mayor’s: “Obviously, the best place to swim within the harbour is within one of the estuarine swimming enclosures.”

At Balmoral, this refers to the Balmoral Baths, the Council-managed enclosed swimming area that separates swimmers from the open harbour.