Establishing a marine park in Channel Island waters would be "disastrous", the president of the Guernsey Fishermen's Association has said.
The French Maritime authorities are discussing the possibility of marine parks in the Baie de Granville area with Channel Island authorities.
Dougal Lane said the move would not improve fish stocks.
He said any suggestion that more seabed could be lost to fishing was "nothing short of a disaster".
Mr Lane said island fishermen were already under huge pressure as a result of recent increases in fuel prices and the threat of the loss of fishing areas to tidal and wind power generation schemes.
He said: "At some time in the year all the seabed is used and we're certainly going to have at some stage massive tidal energy round the islands and that is going to create in real terms a marine park.
"You won't be able to fish round it and there'll be massive structures for the fish to sit behind, we only have a three mile limit so you're talking about a very small amount of water in Guernsey."