The dolphins caught in the fishing net. Photo/Supplied

The skipper of a fishing trawler has been lauded for his decision to dump 30 tonnes of jack mackerel in order to save a pod of dolphins entangled in a net.

Sanford corporate communications general manager Fiona MacMillan said the vessel, the San Columbia, was purse seine fishing off the Tauranga coast on March 23 when the pod of dolphins got caught in the boat's net.

The crew tried to free the dolphins by lowering the sides of the net, but that didn't encourage them to swim out.

The skipper faced a tough choice at that point: If he took further steps to free the dolphins, he risked losing his catch of 30 tonnes of jack mackerel. If he did nothing, the dolphins might die.

"He believed that his priority was to try and save the dolphins. So he made the decision to release one end of the net at the bow, and that enabled all the dolphins to swim away, totally unharmed.

"In the process all the jack mackerel escaped too," MacMillan said.

Despite no fish being caught, Sanford was legally required to report the jack mackerel as catch, and it counted against the company's annual catch entitlement for this species.

"Costs comes second in a situation like this with Sanford's focus on sustainability."

Sanford supported the skipper's decision, Ms MacMillan said.

The skipper was an experienced fisherman who had been fishing for 40 years. He avoided fishing when dolphins were present, she said.

Recreation fisherman Paul Bowyer was fishing near the trawler with two friends and saw the drama unfold.

Mr Bowyer said he often spotted dolphins out on the water around Tauranga and was pleased the fishing crew chose to save them.

"It was a shame that they lost their catch... but they made the right decision to let them go," he said.