Environmentalists have called for a ban on commercial fishing and dredging off East Anglia's coast.
Conservationists want part of the North Sea as a marine reserve
Greenpeace wants the Dogger Bank and other parts of the North Sea - up to 40% of the area - to be a marine reserve like a land-based country park.
Campaigner Sarah Duthie of Greenpeace said that it would be a major step in protecting sea life.
Fishing groups want to hear more about the plan and the Government says much is already being done.
Ms Duthie said the conservation area off the coasts of Norfolk, Suffolk and Essex, would be a major step in protecting sea life.
"If you want your children to be able to eat cod or mackerel, or be able to see dolphins in the North Sea,
then you should support the idea of large scale marine reserves, essentially national parks at sea," she said.
"Today's situation, where scientists are warning that cod could disappear from the North Sea in the same way they did from Canada's Grand Banks yet we carry on fishing, is total madness.
Greenpeace have compiled a report making the case for marine conservation areas and have provided maps of the sea off the East Anglia coast based on their scientific survey data.
The maps are said to show ecologically important habitats as well as fish spawning and nursery grounds.
The report also outlines the many threats facing the North and Baltic Seas from over-fishing, mineral extraction and global warming.
The report is critical of the Common Fisheries Policy and the Habitats Directives arguing that these regulations are failing to reverse drastic declines in fish stocks and in populations of other marine species.
Matt Mander from King's Lynn-based Eastern Sea Fisheries said: "We are interested in what they have to say but they're not new ideas.
Important spawning grounds
"We can agree in principle that reserve areas are sometimes good for the industry. It has worked for mackerel fleets off the south west peninsula.
"Everyone recognises the importance of certain parts of the sea for spawning and the development of good stocks.
"However, this seems to point to a seasonal restriction on fishing rather than an outright ban. We would like to see their maps and data, especially about spawning areas.
"Our fleets are mainly inshore now after the beam trawlers based at Lowestoft to catch plaice went to Dutch owners."
He added: "But other species of fish are important to us and protecting spawning grounds at critical times of the year interests us."
Fisheries minister, Ben Bradshaw - who relies on data from the Centre for Environment, Fisheries and Aquaculture Science, based at Lowestoft - said: "The new CFP includes a requirement for recovery plans for stocks which are outside safe limits.
"The key element is to reduce fishing pressure on the threatened stocks.
"Some stocks - shellfish generally and North Sea haddock and herring - are doing well."