The French fishermen are protesting despite an increase this year of 30 per cent in the cod quota and 10 per cent in the amount of sole they are allowed to catch.

The increases were agreed last December by ministers from all 27 EU countries after scientific advice showed a modest recovery in cod stocks in the East Atlantic and North Sea — two of France’s main fishing grounds. They followed an increase of 11 per cent in the permitted cod catch last year after a decade of annual cuts.

Experts agree that there are still too many fishing boats taking a share of the quota in European waters for them all to survive and are calling for radical policies to enable cod stocks to recover fully.

Part of the problem is the failure of the EU to agree a common policy on discards — edible fish thrown overboard because to take them back to land would mean penalties for exceeding quotas.

Conservation groups say that in 2007 fishermen landed 24,000 tonnes of cod in the North Sea but threw another 23,000 tonnes overboard to avoid breaking quota rules.

Fishermen across Europe face the same dilemma — stocks are controlled tightly to allow for the sustainability of the fish that the industry needs to survive, but the quotas and restrictions on days at sea mean that there cannot be enough fishing for the entire fleet and encourage massive discards.

The EU Commissioner for Fisheries and Marine Affairs, Joe Borg, has called for sweeping reforms to the quota-based system. In February he said: “We have to get out of the current situation, where too many boats are chasing too few fish.”

The need to safeguard future stocks has resulted in 60 per cent of the British fleet being dismantled in the past six years.

“The fishing has been stopped by the French authorities, who are managing the quotas,” the European Commission said. “Fishing quotas are debated by member states every December and the decision is based on scientific advice. This showed that there were good signs of [cod] recovery in two zones. But how long this lasts depends on how many boats there are.”

Xavier Pastor, executive director for the fish campaign group Oceana, said: “Most fish stocks are still being legally and illegally overfished because of EU fishery ministers’ decisions.”

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