The Green Party wants to spend up to $20 million helping fishers adapt to new rules to protect the critically endangered Maui's dolphin - which it plans to introduce if elected.
The party on Wednesday morning announced its plan to save the dolphins, of which only 55 adults remain in the world.
It wants to ban all fishing methods lethal to dolphins, as well as new oil and gas exploration, and seabed mining, in the Maui's sanctuary on the North Island's west coast.
Party co-leader, Metiria Turei, said National's policies are driving the dolphin to extinction.
"What kind of sanctuary is it when a full third of its area is blanketed in minral exploration permits? What part of sanctuary has National not understood? It's much closer to slaughterhouse than to safehouse."
Metiria Turei said the party would also extend a ban on set nets and trawl nets beyond the sanctuary.
The Greens said that would cost fisheries about $13.5 million a year.