All areas of the Coromandel scallop fishery will now be fully closed for three months as the shellfish's population continues to decline.
In March, the government shut down scallop fisheries in Northland, most of Coromandel and the Hauraki Gulf due to depletion - except for around Little Barrier / Te Hauturu-o-Toi and Colville channel.
In a statement, Oceans and Fisheries Minister David Parker said he was enforcing "emergency measures" to protect scallops and their habitats while officials undertook a full review of the fishery.
"This kind of measure is rarely used, and I do not invoke it lightly as it bypasses public consultation," Parker said.
"I consider that in this case, given the seriousness of the situation, it is necessary to protect these scallop beds and ensure the recovery of the wider fishery."
A 50 percent reduction in scallops was seen in Coromandel in 2016, but a new camera-based survey of the beds indicated there was still a serious decline in numbers.
"Those results paint a very dire picture," Parker said.
"While the results are yet to be published, it is clear these scallop beds have declined considerably, and immediate action is required to provide the best chance of recovery."
He was worried the summer season would place further pressure on the scallops' habitat.
"While the effects from fishing will have played a part, it is very likely there are other factors driving the decline including sedimentation from land activities, water quality, and environmental conditions likely linked to climate change."
In the past 20 years, scallops have been fished out in Marlborough, Golden Bay, Tasman Bay, Kaipara, Stewart Island, Wellington and the Chatham Islands.
Minister defends keeping two parts open
Forest & Bird spokesperson Bianca Ranson said they strongly endorsed the minister's action.
"This collapse is a sign that our moana is in serious trouble. We need urgent action to save our tipa and the wider Hauraki Gulf."
Significant and urgent action was needed to restore the mauri of the Hauraki Gulf, Ranson said.
"We need urgent transformation of fisheries management to encompass whole ecosystems, not individual species, and we need to see much better management of agriculture, forestry and urban development to reduce coastal pollution."
At the time of the initial closures, Ngāti Manuhiri chief executive Nicola MacDonald called on the minister to support the Ngāti Manuhiri Settlement Trust application to close the remaining fisheries.
The scallop beds around Little Barrier were a vital source of broodstock for other scallop beds in the Hauraki Gulf, MacDonald said.
In April, Forest & Bird also urged the minister to close the entire fishery.
Parker defended his decision to keep two parts of the fishery open since March, saying the advice from Fisheries New Zealand was that those areas could sustain some fishing.
"I instructed officials to make sure the open areas were monitored.
"Camera-based surveys were carried out in June to August, as a baseline for future monitoring."
The closure takes effect from 16 December and includes commercial, recreational, and customary fishing.
The Coromandel scallop fishery is being reviewed, with a longer term closure proposed, as part of Fisheries New Zealand's regular sustainability reviews for the 1 April fishing year.
Consultation on proposals will begin from Thursday.