Three tiger sharks have been shot and killed after being caught in drum lines in the Whitsunday Islands in north Queensland, where two tourists nearly bled to death after being mauled within 24 hours of each other.

Key points: Authorities say the sharks shot and killed were between 2 and 3.3 metres long

Authorities say the sharks shot and killed were between 2 and 3.3 metres long 46-year-old Justine Barwick remains in the intensive care unit in a Brisbane hospital after undergoing 18 hours of reconstructive surgery

46-year-old Justine Barwick remains in the intensive care unit in a Brisbane hospital after undergoing 18 hours of reconstructive surgery 12-year-old Hannah Papps remains in a critical but stable condition in the Queensland Children's Hospital in Brisbane

A spokesman from Queensland Fisheries has confirmed the sharks measured 3.3, 2.6 and 2 metres long.

Jeff Krause, manager of the shark control program for Queensland Fisheries, said it was not yet clear whether these were the sharks responsible for the attacks on 46-year-old Tasmanian woman Justine Barwick and 12-year-old Melbourne schoolgirl Hannah Papps.

"They will also measure the jaws as well if that can be any assistance to identifying if this was the species involved in the two unfortunate incidents," he said.

"When they get photographs of the bite marks and work out angles of teeth and puncture marks and try and line them up with a certain species of sharks, so hopefully with these measurements it might be able to shed some light if these were the sharks involved.

"But that'll be up the experts to try and determine that."

Queensland Fisheries said sharks are definitely active in Cid Harbour where the attacks happened, and is urging people not to swim in the area.

Authorities said they would not be able to confirm whether the sharks were responsible for the attacks. ( Instagram: sailingpopeye )

Mr Krause said tiger sharks were "very dangerous".

"Even the 2-metre one — tigers are renowned for attacking humans — there's quite a lengthy history with attacking humans, so both very dangerous," he said.

"The Queensland Government believes that human life must come first, so I know people have different views on the shark control program, but we've had two severe shark attacks within 24 hours of each other and we've got to try and make the waters in that area safer for people to swim in.

"We're only wanting to remove — not all sharks, it's not a cull — but we need to remove a few sharks out of that area.

Mr Krause said in terms of size, 5.5 metre tiger sharks had been caught along the Queensland coast in the past.

He urged the public to heed the warnings not to swim in the area.

"It's still quite obviously dangerous, especially catching these [three] large tiger sharks, it's not a good place to swim at the moment," he said.

The fisheries crew at Cid Harbour are due to return to port on Monday morning, where they dock at Abell Point Marina at Airlie Beach.

Authorities said the drum lines would remain in place for a week.

Shark victims remain in hospital

Hannah Papps remains in a critical but stable condition in the Queensland Children's Hospital in Brisbane.

Ms Barwick, an aged care worker, remains in the intensive care unit at the Royal Brisbane and Women's Hospital after undergoing 18 hours of reconstructive surgery on her injured right leg.

Justine Barwick remains in the intensive care unit in a Brisbane hospital. ( Supplied: Family Based Care )

Ms Barwick's boss — the chief executive officer of Family Based Care Tasmania, Douglass Doherty — released a statement earlier on Saturday on behalf of the family.

Quoting her husband Craig Barwick, the statement said: "The surgery took much longer than we were anticipating finishing at 1:00 this [Saturday] morning."

During the surgery specialists repaired ligaments and other structures including nerve, skin and muscle grafting to reconstruct the injured limb.

"It looks like they have done an amazing job, it looks like it has always been there."

Mr Doherty said she was not out of danger yet though, as there was still a threat she could lose her leg.

"The prognosis I would say is guarded. The prognosis of her survival has improved significantly [but] the prognosis in respect of saving a limb — that is guarded," he said.

"But I would say the worst is over.

"Justine is a fighter and a fantastic person. There has been an outpouring of support and personally we are just here to help."