Leaked documents suggest the government may perform a U-turn on its promise to safeguard marine species in a network of protected reserves.
So-called “no-take zones”, where fishing is banned, are considered vital for allowing fish stocks to recover from over-exploitation.
But a “no-take” element will be absent from plans being drawn up by the UK government, the documents suggest.
Reserves will be designed to protect only certain species or habitats.
The Daily Telegraph newspaper says they will be put in place by local sea fisheries committees, which conservationists say are institutionally biased towards commercial fishing interests.
The details reportedly come from a presentation given to conservationists by staff from the Department for Environment Food and Rural Affairs (Defra).
A highly protected marine reserve network was promised by Fisheries Minister Ben Bradshaw at the Marine Conservation Society’s conference last year.
Wildlife Link, a conservation umbrella group, has said that if the government does not impose no-take zones “we will consider the Marine Bill to be a failure”.
Jean-Luc Solandt, biodiversity officer for the Marine Conservation Society, said his organisation was “dismayed” by the government’s change in stance.
“Ben Bradshaw said he was ‘confident’ that the government would be able to meet what the society wanted regarding marine reserves,” Mr Solandt said.
“The current position is far from that. Instead, the government is intent on setting up another set of marine protected areas based on the same failed management structures as European special areas of conservation.”
A Defra spokesman told the Telegraph: “We’re not running away from any commitments. There will be flexible marine protected areas which take account of the marine life they are designed to protect.
“They will be ‘no-take’ where species have dwindled to the extent that they have to be built up.”