At least 20 per cent of the Hauraki Gulf Marine Park would be protected under ambitious new proposals designed to reverse dwindling fish numbers.
The proposed changes could see large swathes of the Gulf placed in marine reserves or made off limits to fishing to help marine species rejuvenate.
The Hauraki Gulf Forum - made up of council, government and tāngata whenua representatives - also voted at a meeting this week to work to restore 1000 square kilometres of shellfish beds and reefs which have been destroyed by decades of plunder.
The forum's State of Our Gulf 2017 report showed trevally numbers had plummeted 86 per cent from their historic levels, snapper 83 per cent, and sharks - a key part of the ecosystem - 86 per cent.
The Gulf covers an area of more than 1.2 million hectares. But it is estimated to support less than 45 per cent of the fish "biomass" that it did in 1925, and crayfish numbers have plummeted to about 20 per cent of their 1945 levels.
Chairman John Meeuwsen said if the proposals were implemented they would help to turn around some of those declines.
The proposals have been slammed as not ambitious enough by recreational group New Zealand Sports Fishing Council, and met with caution by Seafood New Zealand, which represents commercial fishers.
Meeuwsen said the 20 per cent protection figure was about achievability.
The exact forms of the protections was yet to be determined, but could include no-take marine reserves, restrictions on fishing methods, and rāhui, among others.
There was currently no trawling or purse seine allowed in the inner Hauraki Gulf but Meeuwsen would be pushing for "more significant" measures and wanted a minimum of 10 per cent "no-take" marine reserves.
Hauraki Gulf headache: Snapper, sharks, trevally stocks collapse
Govt offers hope in master plan to save Hauraki Gulf
Stagnant master plan to save gulf 'could have been done better'
Currently 0.3 per cent of the Gulf was protected as marine reserves at six sites.
The exact form of the protections and where would be determined through wide consultation , Meeuwsen said.
"These sorts of proposals have failed in the past in not bringing the affected communities along, so we are very strongly stressing the need to develop more detail and have proper consultation."
The forum's proposals had taken into account the Sea Change Marine Spatial Plan, produced in 2016, but which had been marred by delays and funding issues .
University of Auckland Professor Simon Thrush, who heads the Institute of Marine Science, said the proposals were positive, given the "largely negative" changes seen to the gulf.
"We've seen growing evidence of the impact of sedimentation in smothering shellfish and habitat, no changes in nutrient loads entering the Firth of Thames, various changes associated with the climate, and are not seeing any changes in terms of the broad issues around overfishing.
"So this is a great effort to reverse that, and to get more people involved."
The best science available showed about 30 per cent of an area should be protected to support recovery and resilience of marine ecosystems, involving ideally no-take marine reserves, Thrush said.
Even the Gulf's current reserves, covering just 0.3 per cent, had a "major influence" on fish stocks.
"We have been able to document spill-over from just the Goat Island marine reserve all of the way down to Whangaparaoa. That shows 10 per cent of their parentage comes from that tiny area."
Thrush was also supportive of the ambition to restore reefs and shellfish beds, many of which had been destroyed through overfishing, habitat disturbance from trawlers, and in many areas smothered in sediment and run-off from land-use change.
Forum deputy chairwoman Moana Tamaariki-Pohe, one of six tāngata whenua representatives on the forum, said she had seen a dramatic decline at Okahu Bay, on the doorstep of her hapū, Ngāti Whātua Ōrākei.
"As a young person we used to collect pipi on the way home, and catch flounder in the bay."
She said tāngata whenua supported restoring the health and mauri of Tīkapa Moana/Hauraki Gulf.
Recreational fisher Kevin Honeybun, 65, has fished in the Hauraki Gulf much of his life and seen some dramatic changes.
"When I was a young boy the fishing was ridiculous. I grew up in Howick, and you could catch huge snapper in a dinghy just off the beach."
Honeybun said the worst time for fishing was in the 1980s, but he felt stocks had partially recovered since then.
"I think people generally are more aware and are not taking more than they need."
Still, he supported any proposals to protect areas because it would boost fish stocks for future generations.
For Scott Macindoe of the New Zealand Sports Fishing Council, however, the proposals did not go far enough.
Macindoe said he supported "respectful" commercial fishing in the Gulf, but wanted to see the forum push for 100 per cent under some form of protection, and at a minimum trawling banned.
"The SeaChange working group agreed to phase out trawling, Danish seining and dredging as fishing methods, so I can't understand why they haven't been more ambitious and aimed for 100 per cent."
A Seafood New Zealand spokeswoman said they agreed any marine environment "under pressure" should be protected, and supported a "more holistic approach".
"For protection to be successful it needs to focus on the most pressing risks and use the most appropriate management responses to address those risks."
As the forum had no regulatory power, Meeuwsen said their next steps were to produce papers to support the proposal, launch consultation with the affected communities and work with Government agencies.
Developing any marine reserves would require Government action.
Meeuwsen said it would be "wonderful" to see their proposals in place within 10 years, and he hoped the Government would have announced something indicative by 2021, with Auckland hosting major events including Te Matatini, the America's Cup and APEC.
Q & A
What is the Hauraki Gulf Marine Park?
Hauraki Gulf Marine Park covers an area of more than 1.2 million hectares, and includes the Hauraki Gulf, Waitemata Harbour, Firth of Thames and the east coast of the Coromandel Peninsula.
What is the Hauraki Gulf Forum?
The 21-member Hauraki Gulf Forum exists to promote integrated management, protection and enhancement of the Gulf. It includes representatives of the Ministers of Conservation, Fisheries and Māori Development, representatives of the tāngata whenua of Tīkapa Moana (Hauraki Gulf) nominated by the Minister of Conservation, and elected representatives of the region's councils .
How much of the Hauraki Gulf Marine Park is fully protected at present?
Just 0.3 per cent is in no-take marine reserves, split among six small sites.
How much of the Hauraki Gulf Marine Park is covered by shellfish-beds and reefs?
We are not sure exactly, but it is a shadow of its former self having been thoroughly dredged and exploited. Records suggest up to 1500sq/km of shellfish-beds and reefs once called the Marine Park home. It would be a tiny fraction of that at present.
What impact does a recommendation from the forum have?
The forum's recommendations are not binding, but it does carry political weight. It will be up to the forum's members, and other stakeholders, to act on the recommendations.