DNA authentication of fish products reveals mislabeling associated with seafood processing

Abstract

Seafood mislabeling is a problem worldwide because it may cause underreporting of species exploitation and have detrimental effects on endangered species conservation. The persistence of this problem has been documented for important commercial species, revealing the need to devote more effort to provide effective management and control measures. In this study, we have applied DNA authentication tools, sequences of two mitochondrial genes, for authentication of 245 samples of fish marketed in Spain, one of the top fish consumer countries in the world. Fresh, frozen, smoked, salted, and cooked products were analyzed. Successful DNA extraction and positive polymerase chain reaction (PCR) amplification were obtained for all products. DNA sequences revealed greater than 7% mislabeling, unequally distributed among products, fish groups, and supply points where samples were obtained. Significantly higher mislabeling was found for unrecognizable processed products than for whole fish, suggesting that mislabeling is likely deliberate. Lower mislabeling occurred in samples purchased from local grocery stores in comparison with bigger supermarkets, wholesalers, and restaurants. In the case of anglerfish, underreported exploitation of the species from the Pacific Ocean is likely. The results emphasize the need for controlling the labels in different points of the fish supply chain and authenticating species, particularly in processed seafood.