The likelihood one rogue shark is responsible for two attacks in less than 24 hours in Queensland's Whitsunday Islands is almost nil, shark experts say.
Marine Biologist Blake Chapman said it's more likely the Cid Harbour attacks were a mistake by sharks that had strayed into the area due to changed environmental conditions, such as prey movement.
"I imagine (the victims) weren't able to be removed from the water straight away, which tells me the shark wasn't trying to consume them or carry out a prolonged attack," Dr Chapman told AAP.
Melbourne girl Hannah Papps received a life-threatening wound to her leg on Thursday, a day after Tasmanian woman Justine Barwick, 46, was also bitten on her left thigh while snorkelling in the same harbour.
The 12-year-old's family thanked her rescuers, along with paramedics and staff at the Lady Cilento Children's Hospital, where she remains in a critical but stable condition.
Ms Barwick has also been transferred to Brisbane and is in a stable condition in the intensive care unit at the Royal Brisbane and Women's Hospital.
Dr Chapman says the only recorded incident of the same shark attacking multiple people was in Eygpt in 2010 when five people were attacked within minutes, leaving one German woman dead.
Fisheries Queensland set three baited drum lines in the harbour on Friday morning at Sawmill Bay, which will remain in place for a week.
The department's shark control program manager Jeff Krause said it was too early to determine what species of shark was responsible for the first attacks in the area in eight years.
However, in other areas of north Queensland the shark control program targets Tiger and Bull sharks.
Sharks And Rays Australia lead scientists Dr Barbara Wueringer said the drum lines only had a slim chance of working.
"Sharks can cover very large distances, so the chances of catching the same animal responsible for one of the attacks is very unlikely," she said.
The charter company on whose yachts the attack victims were staying is warning its customers to stay out of the water.
Both were sailing with Queensland Yacht Charter vessels at the time.
Managing director Christophe Vanek says all its clients on the water have been warned to be vigilant and refrain from swimming in Cid Harbour and the broader Whitsundays for the foreseeable future.
"We're are also working with relevant government agencies in relation to both incidents," Mr Vanek said in a statement on Friday.
The area is expected to be inundated with tourists in the coming weeks with school holidays starting in Queensland this week.
Australian Associated Press