Depleted scallop fisheries in Northland, most of Coromandel and the Hauraki Gulf are to be closed to allow them time to recover.
Fisheries Minister David Parker said results of a biomass survey in 2021 are alarming and strong measures are needed to restore the fisheries.
"Scientific surveys of scallop numbers in the Northland, Hauraki Gulf and Coromandel fisheries have confirmed iwi and community concerns that scallop beds in the region are in bad shape. I share their concerns.''
Parker said many fishers in these areas had reported it was becoming harder to find scallops.
He said the decline was caused by a number of factors, including sedimentation, dredging and the use of GPS technology to locate and exploit scallop beds.
"Removing fishing pressure is an important and immediate measure that can contribute to their ongoing sustainability. It is the responsible action to take.''
The closure of the fisheries follows a 50 percent reduction in Coromandel in 2016 and a reduction in Northland of 74 percent in 2020.
The scallop ban comes into effect on Friday.
It will fully close commercial and recreational scallop fishing in the Northland fishery, Hauraki Gulf and Coromandel fishery, apart from two defined areas around Hauturu/Little Barrier Island and near the Colville Channel.
Hauraki Gulf Forum co-chair Pippa Coom said the decision to leave open two areas of the Hauraki Gulf to commercial and recreational dredging was "very concerning".
"These are two of our most beautiful islands, with Hauturu one of the most protected places on the planet. It makes no sense for the health of the gulf, and the health of our communities, to have the seafloor around such treasured whenua being dredged."
Coom said the forum would continue to advocate for a completely dredge-free future.
"Both of the areas the minister has chosen to leave open to dredging are covered by tikanga rāhui laid down on Waitangi Day this year, and a formal s186a Fisheries Act application for a temporary closure," forum co-chair and Ngāti Manuhiri Settlement Trust chief executive Nicola MacDonald said.
"The decision today diminishes the mana of the iwi, hapū, whānau, communities and all those involved in supporting the rāhui. The minister should reconsider this aspect of the decision, and/or confirm the temporary closure application."
Forest & Bird Hauraki Gulf coordinator Bianca Ranson said allowing dredging to continue in the area of Ngāti Manuhiri's tikanga rāhui shows disregard for iwi leadership and efforts to protect their rohe moana. It undermines what could have been a great decision".
"We are concerned that these last remaining areas, if left open, will be hit hard by the tipa dredgers and this could do long-term damage in an area that Ngāti Manuhiri is trying hard to protect."
"The minister needs to urgently approve the Ngāti Manuhiri application for a temporary closure so that their tikanga rāhui can be enforced, and to prevent the destruction of these important scallop beds," Ranson said.