A young fisher who caused a stir after reeling in and releasing a bronze whaler shark in the Coromandel said he was "helping the species".

Jack Alexander, 17, was among a group of people who hauled the shark to shore at Pauanui beach before cutting a hook from its mouth, tagging and releasing it back into the sea.

Alexander said he goes to the Coromandel every summer as part of a group who catch and tag sharks before releasing them.

"We are helping the species.

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"This was nothing out of the usual. The shark was only out of the water for two minutes and had water going through its gills the whole time."

The student said he has been fishing for years and is passionate about sharks, having tagged about 25 last summer.

"We bring them up onto the beach, tag them and write down all their details. Tagging the sharks means if they are caught you can track how much weight it has put on, its length, its movements and where its been breeding."

The group copped criticism on social media, including claims that their treatment of the shark was inhumane.

A witness said the shark was not handled with care and she was shocked at what she saw.

"They dragged the shark up the beach ... and had to take a few goes to cut the hook out of the lip.

"Then to require a selfie."

Alexander said the group normally take a photo of each catch before it is released and he does not want to get involved with what is being said on social media.

"These people have probably never touched a fish in their lives.

"For a shark that weighs say 150kg, a hook is like a pin prick. They all swim away strong."

Aucklander Simon List was walking along the shore when he spotted the group pulling something in from the surf at the north end of the beach.

"One of them was wearing one of those big fisherman's belts, and I was thinking that was a bit overkill ... and then all this water started splashing," he said.

"We ran over there and could see this bloody great shark was there. It was incredible."

As List began filming the hefty catch on his phone, he said he was impressed at how calm the young people were as they set about releasing the hook from the shark's mouth, tagging it and setting it back into the sea.

"It literally would have been there for three or four minutes between getting it on to the sand and back ... but the main thing was how cool they were. There was no yelling, squawking or high fives afterwards ... it was like they were doing their job."

List, who has been holidaying in Pauanui for 20 years, said he'd never seen anything like it before.

"Normally you'd be running around like an idiot, but these guys weren't."

List said he believed the shark would have measured around 2.5 metres long.

NIWA's principal scientist for fisheries, Dr Malcolm Francis, said the shark would not have been harmed if it was handled properly and released quickly.

"Sharks are fairly hardy.

"There are a lot of fisherman around who catch sharks accidentally. I just encourage everyone to release them as quickly as possible when they catch them."