A Guardian Seascape analysis of 44 recent studies of more than 9,000 seafood samples from restaurants, fishmongers and supermarkets in more than 30 countries found that 36% were mislabelled, exposing seafood fraud on a vast global scale.
Many of the studies used relatively new DNA analysis techniques. In one comparison of sales of fish labelled “snapper” by fishmongers, supermarkets and restaurants in Canada, the US, the UK, Singapore, Australia and New Zealand, researchers found mislabelling in about 40% of fish tested. The UK and Canada had the highest rates of mislabelling in that study, at 55%, followed by the US at 38%.
Sometimes the fish were labelled as different species in the same family. In Germany, for example, 48% of tested samples purporting to be king scallops were in fact the less coveted Japanese scallop. Of 130 shark fillets bought from Italian fish markets and fishmongers, researchers found a 45% mislabelling rate, with cheaper and unpopular species of shark standing in for those most prized by Italian consumers.
Other substitutes were of endangered or vulnerable species. In one 2018 study, nearly 70% of samples from across the UK sold as snapper were a different fish, from an astounding 38 different species, including many reef-dwelling species that are probably threatened by habitat degradation and overfishing.
Still other samples proved to be not entirely of aquatic species,with prawn balls sold in Singapore frequently found to contain porkand not a trace of prawn.
Fish fraud has long been a known problem worldwide. Because seafood is among the most internationally traded food commodities, often through complex and opaque supply chains, it is highly vulnerable to mislabelling. Much of the global catch is transported from fishing boats to huge transshipment vessels for processing, where mislabelling is relatively easy and profitable to carry out.