There are fears a decision to allow oil drilling off the Taranaki coast could spell disaster for New Zealand's rare Māui dolphins.

Thirty-five percent of the dolphins' habitat is to be opened up to exploration, and Green Party MP Gareth Hughes says it's a reckless move.

"We're talking about more than 2000km squared. We know that the seismic surveys, the oil rigs, the risk of oil spills could be catastrophic for the species.

"Sadly it's symptomatic of the lack of concern the Government's shown. We pride ourselves on the world stage as clean and green and doing the right thing. Here we are endangering the world most endangered dolphin."

Mr Hughes says a move away from the finite resource of fossil fuels needs to be made.

Only 63 Māui dolphins remain in the wild.

Set-net fishing is likely to be the largest source of Māui dolphin deaths caused by humans, but "the effects of marine mining, drilling, and construction, including seismic surveys" also threaten the world's rarest dolphin, according to the Department of Conservation.

Other threats include pollution, marine litter and being struck by boats.

Nearly 500,000 square kilometres is up for tender in the Government's 2017 block offer, meaning oil and gas industries can make bids for mineral oil and gas exploration in the announced areas. More than 476,600 square kilometres of the offer is off-shore.