Labor, the Greens and a conservation group have slammed what the government's decision to undo years of work by scrapping management plans for the world's largest marine park network.

In a decision announced late on Friday, Environment Minister Greg Hunt said Governor-General Quentin Bryce had re-proclaimed new Commonwealth marine reserves, invalidating Labor's management plans and exclusion zones which would have come into effect next July.

He said all Commonwealth marine reserves and parks, including the new Coral Sea Marine Reserve, would stay but there would now be new management plans, as promised in the election campaign.

"Labor's proposed changes would have meant it was against the law for recreational fishers to cast a line at some of their favourite fishing spots across the country," he said in a statement.

Fishers welcomes the move.

Australian Recreational Fishing Foundation managing director Allan Hansard said Labor's plan to lock fishers out of vast areas of ocean was done to meet a political agenda.

"Australia's recreational fishers should not be locked out of marine reserves unless, after a thorough comparative assessment with other activities such as diving, tourism and defence activities, there is a good scientific reason to do so," he said in a statement.

Labor environment spokesman Mark Butler said the government had used obscure powers to undo 20 years of work started under the Keating Labor government and continued under John Howard.

"The management plans for the marine reserves were based on extensive scientific analysis and informed by serious community and industry consultation - now we will see this all happen again, possibly setting these protections back by a good two years," he said in a statement.

Pew Charitable Trust oceans director Michelle Grady said there was clear and overwhelming public support for safeguarding marine areas and the marine park process had been one of the most consultative in Australia's history.

"This decision casts doubt over a 15-year effort that garnered broad support from scientists, fishermen, conservationists, business leaders, and many others," she said in a statement.

Greens Senator Rachel Siewert said this decision gutted Australia's marine parks.

"The Government is pretending they are committed to marine parks, but this decision effectively eliminates them. This isn't about marine protection, it is about the Government's mates in fishing and industry," she said in a statement.