Four shark attacks struck east Australia in 48 hours, stirring fear and beach closures. On January 18, a 12-year-old boy was critically injured and died after a shark bite in Sydney Harbour. The next day, an 11-year-old's surfboard was bitten at Dee Why beach, followed by a man attacked at Manly, who was also critically hurt. On January 20, a fourth surfer was bitten 300km up the coast. "This is the closest - in both proximity and in time - series of shark bites that I've ever seen in my 20 years of research," said Chris Pepin-Neff, a shark researcher and public policy professor at the University of Sydney. Experts link the attacks to heavy rain flooding Sydney, which brought 127 millimetres of rainfall in 24 hours. This created perfect conditions for bull sharks, which thrive in warm, brackish water near river mouths. "Bull sharks love river mouths and estuaries, so the freshwater flooding was perfect for them," explained Rebecca Olive, senior research fellow at RMIT University. The rain also likely flushed nutrients and sewage into the sea, attracting bait fish and sharks. Shark attack numbers have slowly risen in Australia over 30 years, from about 8-10 per year in the 1990s to 25 per year in recent times. However, experts believe this increase is due to more people using the ocean and better reporting, not more aggressive sharks. "The rate of attacks hasn't risen as much as people entering the water," said Pepin-Neff. Despite public calls, experts reject shark culls. "I am strongly opposed to culling sharks to maintain an illusion of safety," said Olive. Pepin-Neff added, "Killing sharks does not make anyone safer. If attractants stay, sharks will keep coming." To reduce risks, experts advise avoiding swimming after heavy rain and installing safe shark enclosures. "Australians know how to navigate the wild; the ocean is still wild," said Pepin-Neff. "The ocean is never safe, and sharks are not always dangerous. We're in the way, not on the menu."