A 43-year-old man is in hospital with a 20cm gash on his leg after he was attacked by a shark in waters off Ballina on the NSW north coast.

Surfers are again on high alert after one of their own used his board to fight off a shark that was attacking him in waters off Ballina on the NSW north coast.

Lee Jonsson, 43, was bitten on his left calf during an early morning surf at Shelly Beach on Wednesday.

After repelling the shark he managed to get himself back to the beach, apply a tourniquet to the 20cm gaping wound in his leg before driving himself to Ballina Hospital.

He was later transferred to Lismore where he remains in a stable condition.

The attack comes just two days after the death of Melbourne doctor Daniel Christidis, who was mauled by a shark at Cid Harbour in the Whitsunday Islands.

Ballina Shire mayor David Wright said Mr Jonsson was a regular surfer who described the shark as being about 1.5 metres long.

"It dragged him off and he fought the shark with his board," Mr Wright told AAP.

"He came to the shore, dressed the wound and drove to hospital. He's got a 20cm wound.

"It's one of those unfortunate things."

The mayor assured every measure possible will be taken to keep people safe.

Beaches around the Ballina area are expected to be closed for at least 24 hours after a request from police.

NSW Surf Life Saving is using drones, jet boats and jet skis to survey the area.

Don Munro from Lennox Heads-Ballina Boardriders Club described the attack as "frightening".

"There's a percentage of surfers that won't go out but for others they aren't going to stop surfing," he told AAP.

"It puts us on red alert."

He hopes the incident won't affect tourism close to Christmas. He believes the SMART drumlines, where sharks are tagged and released 1km from the shore, have been effective - apart from Wednesday's attack.

"I worry about how it will affect our community and our main industry of tourism. We just don't need that," he said.

Shark nets at Shelly Beach and four others on the north coast were removed in May after a nearly five-month NSW government trial.

NSW Premier Gladys Berejiklian would not say whether the nets will be returned as a result of the attack.

"I am confident NSW has the policies and resources in place to keep our community safe and people using our waters safe," she told reporters in Sydney.

The attack comes almost four years after Japanese surfer Tadashi Nakahara was killed by a shark on the same beach.