Customary fishing and marine farming will not be affected by the creation of recreational fishing parks and some petroleum or minerals activities could be allowed.
When the park was first announced before the last election, National said all commercial activity would be excluded.
However, it has now proposed allowing commercial fishing of some species, "where there is limited competition between recreational and commercial use of a species and there is a strong rationale for commercial fishing to remain".
For example, commercial fishing of flatfish could continue, the discussion document suggests, because they are prolific breeders and are not highly valued by recreational fishers.
The Government has proposed banning commercial fishing of snapper, kahawai, john dory, gurnard, tarakihi, trevally and scallops. Flatfish are also included on the proposed ban list, despite also being given as an example of a fish that could continue to be commercially fished.
Primary Industries Minister Nathan Guy and Environment Minister Nick Smith are due to formally present the Hauraki plans this afternoon.
Recreational fishers would still have to obey bag limits in the new parks, where most commercial fishing would be banned.
The Government expected to pay up to $20 million to compensate for the commercial quota loss in both areas, and would also have to engage with iwi on the plan.
Today's discussion document proposes that compensation will be made after a case-by-case assessment.
Any pay-out would take into account "whether there are any measures that would mitigate the effect of a general prohibition on commercial fishing, such as seasonal or species exemptions".
Up to 21,000 recreational fishers take to the gulf on a typical summer's day. At present, some snapper, flounder, john dory, crayfish and kahawai are caught commercially within the inner Hauraki Gulf.
Details of the proposed scheme have been eagerly awaited since Prime Minister John Key announced the establishment of two marine parks for recreational fishing ahead of the last election.
National had initially said it hoped to publish a discussion paper in November 2014, and Labour has criticised the delay as evidence the scheme had not been properly investigated and was an "election campaign gimmick".
The party's fisheries spokesman Rino Tirikatene said any detail on the plan could well show that it was "riddled with exclusions and exceptions", such as allowing some species to be caught commercially and customary fishing, that would undermine the original promise.
Scott Macindoe, spokesman for LegaSea, an initiative of the NZ Sport Fishing Council, said the time for details to be released pointed to the policy being a populist election sweetener.
The fishing parks would exist within larger and fully exploited fish stock areas, and so were unlikely to grow the size of fish stocks, Mr Macindoe said.
Tim Pankhurst, chief executive of Seafood New Zealand, said the commercial fishing industry would be interested to see the details including any information on compensation to commercial fishers in the Hauraki.
The two species most affected would be snapper in the Hauraki Gulf and cod in the Marlborough Sounds. The inner Hauraki Gulf sits within Snapper 1 -- the area from North Cape to East Cape, where the collision between commercial and recreational fishing interests is most fraught.
Evidence that the fishery was in trouble led to proposed cuts in 2013, which triggered protests and a Government backdown.
The wider reform detailed today will provide for a range of marine protected areas, with the Government saying the Marine Reserves Act 1971 is not flexible enough.
The proposed reform would create four different types of marine protected areas:
• Marine reserves, which would be the same as under the current law.
• Species-specific sanctuaries, would be similar to marine mammal sanctuaries but also be available to other marine life like albatross or great white sharks.
• Seabed reserves, would include prohibitions on seabed mining, bottom trawl fishing and dredging.
• Recreational fishing parks, as currently proposed for the inner Hauraki Gulf and Marlborough Sounds.
