Swimmers and surfers were warned Tuesday to avoid beaches in parts of eastern Australia after four shark attacks in just 48 hours.
Heavy rains stirring murky waters have been blamed for the unusual spike in attacks in New South Wales. Surf Life Saving New South Wales said the turbid water created ideal conditions for bull sharks and urged people to stick to pools until conditions improve.
"We have such poor water quality that's conducive to bull shark activity," the water safety body told national broadcaster ABC.
"Just go to a local pool, because at this stage, we're advising that the beaches are unsafe."
A surfer on the state’s Mid North Coast suffered "minor" injuries after being bitten while catching waves Tuesday, marking the fourth recorded attack over two days.
In a separate incident, a man surfing at Manly was critically injured after a shark bit his legs. Hours earlier, an 11-year-old boy escaped unharmed when a shark damaged his surfboard further north. All of Sydney’s northern beaches remain closed.
On Sunday, a 12-year-old boy was seriously injured while swimming in Sydney Harbour.
"It was a horrendous scene at the time when police attended. We believe it was something like a bull shark that attacked the lower limbs of that boy," said Superintendent Joseph McNulty, New South Wales marine area police commander.
"That boy is fighting for his life now," he told reporters Monday.
Scientists say recent heavy rain likely drew bull sharks toward coastal areas where rivers empty into the sea.
"Sharks, especially bulls, are drawn to freshwater flushes to feed on fish and dead animals as they drift down from rivers," said Culum Brown of Macquarie University.
"Given the incredible rainfall we have had of late, the risk of encountering sharks is high. Stay out of the water till it clears."