The discount grocer Aldi has been named the best British high street supermarket for sustainable fish, according to a new league table.

Some 79% of the seafood range stocked by the fast-growing German discounter is certified sustainable, the annual survey from the Marine Stewardship Council (MSC) found. This year’s results also show that supermarkets are selling more sustainable seafood than ever before – a 60% rise over the last two years.

The MSC is the international NGO that sets the standard for sustainable fishing around the world and its blue label indicates that seafood has been sustainably caught and traced back to its source. More than 20,000 seafood products worldwide now carry the MSC blue fish label.

Second after Aldi is Sainsbury’s, which sells the largest number of certified products – 226 – making up 76% of its wild seafood range. Next is discounter Lidl with 72%, Waitrose on 67%, the Co-op on 61% and Tesco with 48%. For Marks & Spencer, however, the figure is just 19%.

Iceland and Morrisons are lurking at the bottom of the league with less than 5% of their seafood range MSC-certified.

However, the survey only refers to products which are MSC-certified. Both Waitrose and M&S use third party independent verification that is not reflected in these findings.

Many retailers have made commitments to make their seafood range 100% sustainable over the next few years, the survey said. Singled out for the biggest improvements this year was Asda, which increased its certified sustainable seafood range from just 17 to 52 products, now totalling 38% of its range.

“The majority of British supermarkets are making a real investment in the future of their seafood” said Toby Middleton, head of market operations at the MSC. “If you’re buying MSC-labelled fish or seafood in one of these top five supermarkets, you’re helping to make a positive difference to the world’s oceans. Our league table shows that retailers are offering their customers clear labelling and the chance to make a difference, helping to protect fish stocks for our children and our grandchildren.”