A man has used his surfboard to fend off a shark that bit him on his calf off an Australian beach.

The 43-year-old surfer was bitten Wednesday morning at Shelly Beach off Ballina in New South Wales state.

It comes two days after a fatal attack on the Great Barrier Reef.

Australia Shark Attack
The 43-year-old surfer was bitten on Wednesday morning (ABC/AP)

Ballina Shire Mayor David Wright said the surfer described the shark as about 1.5 metres long.

He told Sydney’s 2GB radio the man came onshore, wrapped his leg and went to the hospital for treatment of a 20-centimetre wound.

Beaches in the area are expected to be closed for at least 24 hours.

On Monday, a shark killed a man in a harbour in the Whitsunday Islands, where two tourists were mauled in September.

The victim, 33-year-old doctor Daniel Christidis, had been diving from a paddle board while on a yacht cruise in the idyllic Whitsundays.

Police Inspector Steve O’Connell said the group included other doctors who worked to save him but Mr Christidis was injured too severely.

The spate of attacks in the Whitsundays has left authorities struggling to explain an apparent escalation in danger in the internationally renowned holiday destination.

In September, two Australian tourists were mauled on consecutive days, one a 12-year-old girl who lost a leg.

Daniel Gschwind, chief executive of the Queensland Tourism Industry Council, which represents more than 3,000 tourism businesses, said on Tuesday that authorities were examining why the unprecedented series of attacks had occurred and whether environmental changes were a factor.

“We need to now have the scientific background and investigation of what is causing this sudden spike of attacks and interactions with sharks. We simply do not know why this is occurring and what is responsible for it,” he said.

Authorities killed six sharks in the Cid Harbour area in a week following the September attacks to reduce their numbers.