The Government hopes to protect Maui's dolphins by extending a set net fishing ban off the coast of Taranaki.
Conservation Minister Nick Smith says New Zealand must do everything practically possible to ensure the survival of the last remaining 55 adult dolphins.
The Government wants to ban set nets from Pariokariwa Point to the Waiwhakaiho River, between two and seven nautical miles offshore - an area of 350 square kilometres.
Dr Smith says there have been five reported sightings of Maui's dolphin in the area in recent years.
"Where we have concrete and multiple observations of the Maui being present, we should not allow set netting. Thus this proposed ban."
He met the five companies that fish the area on Friday morning. "The extension of the set net ban area will have a pretty adverse effect on them. I explained to them though that with a species down to such thin numbers the Government must err on the side of the Maui."
Dr Smith expects about five jobs to be lost.
A ban on commercial set nets already exists around Kaipara harbour and one part of the Taranaki coast.
The plan will be open to consultation until 10 October, after which a threat management plan will be finalised.
An Otago University professor in Zoology, Liz Slooten, says the proposed extension is only about 10% of what needs to be done to save the dolphin but Taranaki fishers say the plan is unnecessary and will hurt the industry.