Surfer injured in fourth shark attack in Australian state in 48 hours

10 minutes agoTiffanie Turnbull,SydneyandKoh EweA surfer has been bitten by a shark, the fourth attack along Australia's New South Wales (NSW) coastline in under 48 hours.The 39-year-old man "sustained a wound to his chest" after a shark bit his board on the Mid North Coast on Tuesday morning, police said. He has been released from hospital.It follows three other attacks in Sydney over the past two days. All beaches in Sydney's northern area will remain closed until further notice, said police. The attacks follow days of heavy rains, which NSW Superintendent Joseph McNulty had earlier said may have created a "perform storm environment" for shark attacks. Rain flushes nutrients into the water, which can draw sharks closer to shore.The attack on Tuesday took place near the Point Plomer campground, about 450km (279 miles) north of Sydney.Steve Pearce, the chief executive of Surf Life Saving NSW, said the surfer was "very fortunate to not have sustained any serious injuries", ABC reported. "We really strongly advocate that nobody swim or surf near river mouths because it's obviously an area where sharks congregate," Pearce said. "If it's dirty water I'd think twice about going in there."A young surfer had a similarly lucky escape at Dee Why Beach in Sydney on Monday, but a shark attack at nearby Manly hours later left a 27-year-old with "life-changing" injuries. On Sunday, a 12-year-old boy was also critically injured when bitten at a popular Sydney Harbour beach.Authorities believe bull sharks were involved in most of the recent attacks.Bull sharks, which can be found in both fresh water and salt water, are "one of the few sharks that are potentially dangerous to people", the Australian Museum says. They are the third deadliest shark species, according to the International Shark Attack File.Last November, a woman was killed and a man was seriously injured after being attacked by a bull shark on a remote beach, also on the NSW Mid North Coast.Bull sharks are typically seen around Sydney in January and February - the summer months in Australia - as the "water is at their preferred temperature", Dr Daryl McPhee, associate professor of environmental science at Bond University, told the BBC.Though Australia is a global shark attack hotspot, the chances of being attacked are still minute - making this string of shark attacks in NSW a rare phenomenon. "This series of bites from bull sharks in such a short period of time is highly unusual," said McPhee.Police on Monday advised the public to avoid waterways in NSW due to recent weather, which has decreased water quality and visibility."I would recommend not swimming in the harbour or our other river systems across NSW at this time," Superintendent Joseph McNulty told reporters.Rain can concentrate fish that bull sharks prey on downstream in rivers and beaches, McPhee said, adding that "bull sharks are well adapted to feeding in murky water after rain". "Where you find the fish, you find the bull sharks. Unfortunately, that sometimes occurs at popular beach locations."