The European Commission has banned the fishing of endangered bluefin tuna in the eastern Atlantic and Mediterranean for the rest of the year.
Undeclared over-fishing is causing a decline in fish stocks, the EU says
The move was taken to curb over-fishing and dwindling stocks of fish, after the EU reached its 2007 quota.
An EU official said it would move to prevent under-reporting of catches and unequal sharing of the quota.
The ban affects Cyprus, Greece, Malta, Portugal and Spain. Italy and France have closed their fisheries for 2007.
Member states had already reached the 2007 quota of 16,779.5 tonnes, the EU said.
Countries that had not reached their allocation by the time of the ban could seek future compensation under EU legislation, he added.
EU and international rules also exist to punish member states that exceed their quotas.
"Clearly there are problems both of over-fishing a stock already threatened with collapse and of equity between the member states concerned," said EU Fisheries Commissioner Joe Borg.
France was one of the main culprits, according to figures gathered by environmental group WWF.
"France was one of the countries that has caught most of the [EU] quota ... they have over caught their national limit," Carol Phua, WWF Fisheries policy officer, told the BBC News website.
The endangered bluefin tuna has been plundered for many years in the eastern Atlantic and Mediterranean, with high rates of unreported over-fishing a key cause of the decline, the EU said.
Atlantic bluefin tuna is the best quality tuna in the world, and fisheries earn top dollar exporting the fish to the lucrative Japanese market.
The increasing appetite for sushi in Europe is also pushing up demand.
The International Commission for the Conservation of Atlantic Tunas (ICCAT) sets annual fishing quotas to be followed by all member countries.