The UK is pressing the EU for action to stop overfishing of the bluefin tuna, which campaigners say is being fuelled by the demand for sushi. The environment group WWF says many EU fishing fleets are breaking the law and catching far more tuna than allowed.
Traditionally much of the catch is exported to Japan, but there is an ever-growing sushi market in Europe.
The UK government wants seasonal closure of fishing grounds and stricter rules governing tuna farms.
Demand is currently so strong that single fish can sell for thousands of pounds. With sushi continuing to be a fashionable cuisine, the UK is consuming 600 tonnes a year.