A Formula One-style pit stop to deliver paramedics extra blood might have saved a man's life, as Sydney deals with a shark attack surge.
A swathe of Sydney's beaches have been closed after three suspected bull shark attacks in little more than 24 hours have left two people in critical conditions.
A man in his 20s was attacked at North Steyne Beach at Manly in Sydney's north on Monday evening and underwent surgery for severe lower-leg injuries at Royal North Shore Hospital.
That followed a 13-year-old boy attacked while swimming in Vaucluse in Sydney's east on Sunday, requiring surgery for injuries to both his legs.
An 11-year-old boy narrowly avoided injury at Dee Why, with a shark taking a chunk out of his surf board.
NSW Ambulance Acting Superintendent Christie Marks said the man attacked in Manly suffered heavy blood loss and was in cardiac arrest when paramedics arrived.
He needed 13 units of bloods on his way to hospital, which required highway police meeting the ambulance en route to drop extra supplies off.
“They said it was almost like an F1 pit stop of 10 seconds or less where they just opened the door, blood went in, and then they continued on,” Act Supt Marks said.
“This is something that doesn't happen a lot … that is going to give him the best chance of surviving.”
All of Sydney's Northern Beaches have been closed in response for at least 48 hours.
More than 30 SMART drumlines have been deployed along that stretch of coast, while shark listening stations and aerial surveillance have been ramped up.
Surf Life Saving NSW CEO Steven Pearce said the "turbid and brackish" water created prime conditions for bull shark activity.
University of Sydney public policy expert Chris Pepin-Neff, who has written a book on shark policy, suggested Sydney Harbour's 100-year-old sewage pipes were likely to blame.
The pipes overflow with just 20mm of rain, far less than the 127mm Sydney received on Sunday.
“When the pipes overflow, when there's more sewage, the bait fish eat the sewage and then the bull sharks come to eat the bait fish, and that draws them into the surface and into the shore,” Associate Professor Pepin-Neff told AAP.
“Three shark bites in two days suggests to me there's a unique environmental condition that is more than just the heavy rain."
The primary industries department is working to identify the species of shark involved but initial reports suggest it was a bull shark.
