The European Commission has closed the Mediterranean bluefin tuna fishery two weeks before the official end of the season.
The EC made the move last Friday, saying quotas were virtually exhausted and stocks needed to recover to avoid the overfishing.
The EC said it had been carrying out an "unprecedented inspection and control campaign" this year together with the Community Fisheries Control Agency to help protect the endangered bluefin tuna.
However the WWF said the EC could have done more. "This fishery should never have been allowed to open this year at all," said the organisation's head of European Marine Programme, Aaron McLoughlin.
"Tinkering with the existing fishing season will do little to help because fishing levels even up to now were too high", added senior oceans campaigner at Greenpeace UK, David Ritter.
In April Greenpeace activists stormed the European Seafood Exposition in support of a ban on the sale of bluefish fish.