The incidents happened less than a day after a boy was left in a critical condition with injuries to both legs in a suspected bull shark attack<\/a> near Vaucluse’s Shark Beach.<\/p>\n The boy was taken to Sydney Children’s Hospital at Randwick, where he remains in intensive care.<\/p>\n Northern Beaches Council said all beaches, except for Palm Beach, had been closed for swimming over the weekend due to dangerous surf conditions.<\/p>\n Sewage and sharks<\/p>\n University of Sydney associate professor of public policy Chris Pepin-Neff said swimming in Sydney Harbour after heavy rain was a “terrible idea”.<\/p>\n “After 20 millimetres of rain, the level of faecal matter and raw sewage that are in the harbour attracts bait fish and brings sharks toward the bait fish,” they said.<\/p>\n “It’s really important after a big storm to not swim in the harbour for about 72 hours.” Dr Pepin-Neff says there needs to be better communication about the presence of sharks in the harbour after a storm. (ABC News: Isobel Roe)<\/p>\n Dr Pepin-Neff said flyers were posted around swimming areas to alert the public to elevated levels of bacteria, but the information did not address the risk of sharks.<\/p>\n “They need to put up public notices that tell people not to swim for 72 hours,” they said.<\/p>\n “Those are city sewerage pipes that are flowing raw sewage into the harbour, so I think the city has an obligation … to alert the public that old pipes make the harbour unsafe after a big storm.”<\/p>\n A 12-year-old boy was probably bitten by a bull shark at Vaucluse. (ABC)<\/p>\n Dr Pepin-Neff also thinks that with the combination of sewage, bait fish and murky water, the animal that bit the 12-year-old’s legs was a bull shark.<\/p>\n “Bull sharks are biters. They tend to bite because they’re smaller. They tend to bite more often. It’s a bad recipe if you’re in the water,” they said.<\/p>\n ‘There’ll be more’<\/p>\n Marine Life Rangers founder David Baxter said there were more migratory species like bull sharks in the harbour because of the temperature of the water.<\/p>\n “They’re cruising up and down our breaches,” he said.<\/p>\n “We know [in] the harbour, for example, we’ve got dirty water, then overcast rain, a lot of the run-offs from the creeks and the drains, and that it stimulates the curiosity of sharks.<\/p>\n Mr Baxter says he expects more shark attacks within the harbour. (ABC News)<\/p>\n “We’ve had those two attacks in the harbour, and I’m predicting that there’ll be more.”<\/p>\n Mr Baxter urged people to be cautious.<\/p>\n “If it doesn’t feel right, the conditions aren’t right, just don’t go in,” he said.<\/p>\n![\"A](\"https:\/\/www.newsbeep.com\/au\/wp-content\/uploads\/2026\/01\/a724c3d0281caa5fd8ccf8fff0e28eee.jpeg\")
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