Far North hapū have imposed a rāhui on taking scallops from the Whangaroa Harbour which is expected to be in place for up to three years.
The conservation rāhui will be laid on the entire harbour, and includes Whangaihe Bay, Ririwha (Mahinepua / Stephenson Island), Taupō Bay and Tauranga Bay.
Hapū on the coastal boundaries of the Takou River, further south, and Taemaro, near Hihi, are yet to decide if they will be included in the Māori customary practice that prohibits access to an area or resources.
About 50 people turned out to a hui in Kāeo on Tuesday to discuss the issue, including marae representatives, members of the community and whānau.
Karangahape Marae - with support from Tahaawai, Te Patunga, Te Huia, Otangaroa, Waitaruke and Taupō marae - will open the rāhui with a karakia at 6am on Saturday.
Karangahape Marae trustee Nyree Porter-Manuel said action was needed to protect the harbour for future generations.
The decline of scallops was due to damage caused by numerous large flooding events, along with excessive dredging, coastal erosion caused by forestry and too many boats in the harbour, she said.
"It gives it a break and lets it do what it needs to do – and that's regenerate.
"We can't have dredging in there. It's a different environment down there to what it was 20 years ago."
Porter-Manuel said the marae is working in collaboration with the Ministry for Primary Industries and has had a lot of community support for the rāhui.
Rāhui advisor Reuben Taipari said the two 100-year floods that hit Kāeo in 2007 caused a lot of damage.
"When Kāeo flooded, sediment washed into the harbour and covered the scallop beds and they haven't been able to recover because people are still harvesting them.
"A rāhui is needed so they can recover and establish themselves again and so we can harvest properly.
"Everything else is fine ... kina, snapper, oysters ... it's nothing to do with the marine environment, it's to do with the seabed that needs to be left alone.
"If nothing's done, scallops will become extinct in the Whangaroa Harbour."
Taipari said the area would be monitored by local hapū, who would undergo training.
Signs explaining the rāhui would be erected at various spots including at boat ramps.
Seasonal and annual reports would be carried out and passed on to the marae and MPI.
"Hopefully in two to three years we'll be back on track," Taipari said.
Former NIWA marine biologist Ken Grange, who lives in Kerikeri, was at the hui to share his scientific knowledge.
Grange said the recovery of the sea beds was still possible.
"If the habitat is still there and hasn't been too damaged by dredging there's a possibility they'll come back," he said.
"The other thing about scallops is they need lots of them in an area to successfully breed. If you don't have enough adults together the sperm and eggs don't mix and fertilise.
"They need to be left alone to make sure their habitat is okay so it can self generate, then it should be able to look after itself.
"What the rāhui may also do is allow a bit of research on growth rates or survival without scallops being harvested while research is going on."
Whangaroa resident Ross Guy, who is president of Kāeo Hunting and Fishing Club, said he supports the rāhui as long as it's consistent and applies to everyone.
"It's got to be good," he said.
"Twenty years ago, there were heaps of scallops, and two or three years ago we couldn't find any.
"They move around a lot and there's probably too much silt going into the harbour, and too many fellas from out of town. If you have a look at the fishing along there everyone's on a 6-7m trailer boat."