SYDNEY, Jan. 20 (Xinhua) -- Authorities have closed all beaches in northern Sydney following three shark attacks in two days that left two people with critical injuries.
All 20 beaches in Sydney's Northern Beaches area were closed until further notice from Tuesday, after two of the attacks occurred in the region on Monday.
A man aged in his 20s was hospitalized in a critical condition on Monday night after he was bitten on the leg by a shark while surfing at a beach in Manly, 10 km northeast of central Sydney in the Northern Beaches.
Earlier in the day, an 11-year-old boy escaped without injuries when his surfboard was bitten by a shark at Dee Why Beach, 5 km north of Manly in the Northern Beaches.
Photo analysis of the surfboard bite by the Department of Primary Industries and Regional Development in the state of New South Wales has determined that a bull shark was likely responsible for the attack.
Those attacks came after a 12-year-old boy sustained critical injuries to both legs when he was attacked by another suspected bull shark at a beach on the southern shore of Sydney Harbor on Sunday afternoon.
All three attacks occurred after Sydney received intense rainfall on Saturday and Sunday, causing brackish and murky water conditions in the harbor and the city's beaches.
Chris Minns, premier of the state, said on Tuesday that bull sharks are more likely to attack humans in murky conditions because they identify food by silhouettes.
He told Nine Entertainment radio that the state's warning system and communication regarding water conditions need to be improved, particularly during stormy weather, but said there is no "silver bullet" to prevent shark attacks. ■