EXCLUSIVE: The two fishermen who caught a shark that was later filmed being ridden like a surfboard in Tauranga Harbour are defending their actions and say they regret the incident.

The video of Mount Maunganui man Eddie Bithell riding a dead shark being towed behind a boat was posted on Facebook on Sunday, April 22, and has since caused a stir among environmentalists who say the action is disgusting.

Fishermen Mark Collins, 22, and Zane Roderick, 23, regret the shark riding incident in which their friend was videoed riding a shark on the back of their boat.

Speaking to SunLive Mark Collins, 22, and Zane Roderick, 23, who caught the shark while fishing for Billfish near Mayor Island, say the shark had been dead for more than 30 hours when the incident occurred.

'We didn't intend to kill the shark, it was already dead when we pulled it up and had been for more than 30 hours.

'We really regret it, we weren't going out to kill the shark, but it wasn't a good idea.”

The pair headed out to Mayor Island on a fishing trip in Zane's 22-foot boat on Friday, April 20, when they caught the 289kg shark, which took a total of 10 hours to reel in.

'We didn't know it was a shark at the time, it was only when we pulled it up and it was already dead by then.”

The shark was then fixed to the boat before the pair moored in South East Bay for the night, before returning to Sulphur Point on Saturday where the shark was weighed.

It was then that the pair headed back out with a few friends to return the shark that the ‘riding incident' occurred.

'We were heading about two miles offshore to return the shark.

'We just got carried away in the afternoon's celebrations,” says Mark.

Mark has been fishing since he was 9-years-old and says he always catches and releases sharks.

'I have been fishing since I was little and never caught a shark purposely.”

Photo: supplied.

'If I could change it I would.”

Zane says catching sharks is part of game fishing, but there is a strict catch and release policy and they always adhere to that.

'Whenever we catch a shark they are tagged and released.”

Mark says although he regrets the riding incident he says the shark was not harmed.

'Considering the sharks that get killed in by-catches by commercial long liner boats in New Zealand – they should be focusing on where sharks are actually being hurt and killed.”

The Ministry of Agriculture is investigating the incident.