A "monster" fifth shark has been caught in the same area where a young New Zealand girl and a woman were mauled in separate attacks last week.

Witnesses said the shark appeared to be the biggest yet caught by Fisheries Queensland since a controversial cull began in Cid Harbour on Friday.

One yachtie at the scene told friends: "This one's a monster."

Three tiger sharks were shot by Fisheries Queensland officers on Saturday after being caught on drumlines, installed in the harbour the previous day in response to the attacks. Two were 3.3m in length and the other 2m.

Yesterday, a fourth tiger shark — the biggest to be caught so far at 3.7m — was caught and shot.

Twelve-year-old schoolgirl Hannah Papps, whose parents are from New Zealand, remains in a critical but stable condition after being mauled by a shark in Cid Harbour, north of Hamilton Island, last week.

Four of the sharks caught since the attacks have been tiger sharks.

The tiger shark caught in Cid Harbour on Sunday was 3.7m long.

A Fisheries Queensland spokesman said one of the sharks caught today would have posed a serious threat to people swimming in Cid Harbour.

"The shark has been humanely euthanised and will be taken further out to sea for disposal," the spokesman said.

"The three drumlines deployed last week will remain in place over the coming days.

"The intention is to remove large dangerous sharks from the area and reduce the risk to people.

"Clearly there are a significant number of active sharks in local waters and people are urged not to swim."

Fisheries staff on Saturday caught three other tiger sharks – one 3.3m, one 2.6m and the other over 2m – in the Cid Harbour area. They were all destroyed.

"While sharks of this size are potentially very dangerous to humans, it is unclear if they were responsible for injuries caused to two swimmers this week," a Department of Agriculture and Fisheries spokesman said then.

"Sharks are definitely active in the harbour and this reinforces the Minister's message that people should not swim in the area.''

A woman who lives on a boat in Cid Harbour said the first two sharks had been shot within minutes of each other.

"Five shots were used on second shark. Minutes after first shark," she said.

"Sharks are everywhere. We always catch them."

Three drumlines were deployed in Sawmill Bay on Friday. They will remain there for at least the next week.

The captures come as the first shark attack victim, Justine Barwick, is showing goods signs of recovery following an incredible 18-hour surgery to save her leg.

Her husband Craig said the surgery took longer than anticipated.

He said specialists had "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 Barwick said.

He said that, after two to three weeks in recovery, his wife would be able to return to Tasmania for further rehabilitation.