The Greens want to review New Zealand's fishing Quota Management System, ban bottom trawling and spend $50 million on helping the country's fishing sector become more sustainable.

The party also plans to protect at least 30 per cent of all New Zealand's oceans by 2030 by passing a new law which would create a network of protected marine areas.

The promises are all part of the Greens "Thriving Oceans Plan" – a plan that it says would restore the health and productivity of New Zealand's seas and fisheries.

"Oceans are the lifeblood of our planet and a home to thousands of taonga species," Greens co-leader Marama Davidson said.

But, as a result of successive governments exploiting the ocean for short-term economic gains, she said New Zealand's oceans are under threat.

The Greens oceans plan, which Davidson described as the boldest vision for the ocean protection in decades, would attempt to prevent more damage.

The Greens' policy says the party would:
• Protect at least 30 per cent of New Zealand's oceans by 2030.
• Ban bottom trawling on seamounts and set-netting in the habitats of endangered seabirds and dolphins.
• Review the Quota Management System (QMS) in consultation with Māori.
• Phase out harmful commercial fishing practices in the Hauraki Gulf.
• Spend $50 million on creating sustainable fishing methods.
• Phase out non-recyclable plastic.
• Introduce a 10-year moratorium on seabed mining.

"Here in Aotearoa we love our big blue backyard. If we think ahead, we can protect this precious taonga for generations to come," Davidson said.

She said the Greens would work with Māori if the plan is rolled out.

"The Green Party recognises the customary right of Māori to gather kaimoana and also that Māori have commercial fishing rights under te Tiriti o Waitangi."

The Greens plan is relatively light on detail when it comes to the review of the QMS. The party's policy only says the system "has not sustained healthy fisheries".

The QMS imposes a yearly fish catching limit and is designed to manage fish stocks in New Zealand's oceans.

But the policy does say that one option could be a co-governance system between the Government and iwi and hapū.

A key pillar of the Greens plan is its commitment to reform the Hauraki Gulf Marine Park Act to urgently phase out the most destructive commercial fishing practices.

These include bottom trawling, dredging, and Danish seining in the region.

"We will commit funding to restore 100,000 hectares of shellfish beds in the Gulf, the equivalent of 100,000 rugby fields," the party's policy says.