Sydney Harbour Shark Attack: Expert Calls Swimming After Rain a 'Terrible Idea'

A shark expert says the risks of swimming in Sydney Harbour after heavy rainfall should have been communicated better after a shark attack left a 12-year-old boy in critical condition. His comments came before two other shark-related incidents on Monday. A man was critically injured by a shark at North Steyne Beach at Manly just before 6pm. Just before lunchtime on Monday, a young surfer escaped uninjured after a shark bit off a chunk of his surfboard at Dee Why Beach in the northern beaches. 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 near Vaucluse's Shark Beach. The boy was taken to Sydney Children's Hospital at Randwick, where he remains in intensive care. Northern Beaches Council said all beaches, except for Palm Beach, had been closed for swimming across the weekend due to dangerous surf conditions. Sewage and sharks University of Sydney associate professor of public policy Chris Pepin-Neff said swimming in Sydney Harbour after heavy rain was a "terrible idea". "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. 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. "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." Dr Pepin-Neff also thinks with the combination of sewage, bait fish and murky water, the animal that bit the 12-year-old's legs was a bull shark. "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. 'There'll be more' Founder of the Marine Life Rangers, David Baxter, said there were more migratory species like bull sharks in the harbour because of the temperature of the water. "They're cruising up and down our breaches," he said. "We know 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. Mr Baxter urged people to be cautious. "If it doesn't feel right, the conditions aren't right. Just don't go in," he said. 'Avoid swimming in murky water' In a statement on Monday afternoon, the NSW Department of Primary Industries and Regional Development (DPIRD) said a bull shark likely attacked the 12-year-old. "DPIRD shark scientists are unable to definitively confirm the species based on photos of the injury. However, they believe a bull shark was likely responsible based on the nature of the injuries and the environmental conditions at the site," it said. "Water conditions in the harbour are brackish following heavy rain and runoff, which can worsen visibility. "Advice from experts is to avoid swimming in low visibility, murky water." Marine Area Command commander Superintendent Joseph McNulty said on Monday heavy rainfall may have contributed to the attack at Vaucluse. "We believe the combination of the brackish water, the fresh water, the actions of the splashing, may have made that perfect storm environment for that shark attack yesterday."