The European Commission is closing the bluefin tuna fishing season early because of depleted stocks, imposing a ban that will take effect on Thursday.
The ban covers fishing grounds in the Mediterranean and eastern Atlantic.
It affects industrial purse seine fishing, which accounts for more than 70% of the annual EU tuna catch, the Commission says.
The fleets are concentrated in France, Spain and Italy. The season was originally due to end on 15 June.
Purse seine nets have a rope that is drawn through rings to trap the fish, like a drawstring.
"The closure of the purse seine fishery is necessary to protect the fragile stock of bluefin tuna and to ensure its recovery, as envisaged by the recovery plan of the International Commission for the Conservation of Atlantic Tuna (Iccat)," the Commission said.
"The Commission has declared a zero tolerance approach towards overfishing and will take all necessary measures to ensure full compliance across the board."