The Marine Stewardship Council has called on consumers to pressurise retailers to sell sandwiches made from sustainable tuna.

Speaking as the MSC marked World Oceans Day on Monday, senior country manager Toby Middleton urged supermarkets to follow Sainsbury’s and Waitrose, who have launched MSC sustainable tuna sandwiches. Only a “tiny proportion” of tuna sandwiches carried independent proof of sustainability, he said.