Shark mauls woman in rare Sydney Harbour attack

 A shark mauled a woman swimmer in the first attack in Sydney Harbour in 15 years, officials said Tuesday, sending her to hospital with a "serious" leg injury.

The predator struck Monday evening as the woman swam off a wharf at Elizabeth Bay, less than two kilometres (1.2 miles) from Sydney Opera House, police said.

The woman suffered a "serious injury to her right leg", New South Wales police said in a statement.

It was the first shark attack in Sydney Harbour since February 2009, when an Australian navy diver fought off a bull shark that bit him in the arm and leg in Woolloomooloo Bay.

Neighbours rushed to help the Elizabeth Bay victim, identified by the Sydney Morning Herald as 29-year-old Lauren O'Neill, a keen kayaker.

"I got home from work and sat down on the couch. I heard a soft yell for help just outside the window," nearby resident Michael Porter told reporters.

Outside, he saw the woman trying to climb a ladder out of the harbour's waters.

"Behind her was her leg, which was limp and all completely open and full of dark red blood behind her," Porter said.

"She had obviously been mauled extremely badly by whatever shark it was that got her," he said.

"We have always worried and known about sharks in the harbour," he added. "It's only now that it feels very real."

A veterinarian living nearby gave first aid.

'High-risk time'

The woman was in a stable condition in intensive care at St Vincent's hospital, a hospital spokesperson said.

She was expected to undergo surgery during the day.

Analysis of the shark bite and of images provided by the authorities confirmed "a bull shark was likely responsible", said shark scientist Amy Smoothey.

Sharks are "more actively feeding" in low light at dawn and dusk, she told national broadcaster ABC, making it "potentially a high-risk time to be swimming".

Scientists have tagged 87 large bull sharks in Sydney Harbour since 2009, said Smoothey, who works for the New South Wales department of primary industries.

Tagging indicated that bull shark numbers in the harbour were at their highest in the Australian summer months of January and February, she said.

"Shark bites are really rare although they are very tragic when they do occur and my thoughts are with the victim," Smoothey said.

"There are very few interactions that occur in our enclosed waterways but we know that bull sharks are one of the top three species involved in shark bites."

In February 2002, 35-year-old British diving instructor Simon Nellis was devoured off Sydney's ocean beach Little Bay in the first fatal attack in the city since 1963.