A Nelson surfer suffered a deep puncture wound to his hand while wrestling a 2m shark during the weekend.

Laine Hobson, a teacher at Nelson Intermediate, was surfing off Snapper Pt, northeast of the city, on Saturday when he was nudged by the shark - possibly a bronze whaler.

"It wasn't like Jaws coming at me viciously. It came up and nudged me on the thigh while I was sitting on my board. It gave me a shock but I pushed it away with my hand, then it cruised around in front of me and gave me another nudge on the other leg," he told The Nelson Mail.

"I was then trying to keep the board between me and the shark - I was probably screaming by then - there was another guy close to me. Then the shark nudged me off my board and leapt on top of it and was thrashing about."

Mr Hobson, who was surfing with eight others, said he then noticed his hand had a deep puncture wound and was bleeding profusely.

"Everyone was out of the water at that point. It was quite horrible actually, because this wave came along and picked up everyone else and carried them in, but it missed me. I couldn't get a break," he said.

"I don't know if the shark followed me in. I was concentrating on the shore and going as fast as I could, while trying to keep my toes out of the water.

"Being a surfer, you read about these things happening but I never thought it would happen to me."

Department of Conservation shark expert Clinton Duffy said the encounter was unusual.

"I can't recall any similar incident with a bronze whaler and surfer in New Zealand. It's more typical of a bronze whaler being attracted to a spear fisherman, when they can become persistent and aggressive."

Mr Duffy said sharks responded to highly contrasting colours. Mr Hobson's surfboard was brightly coloured.