Inaccurate labelling detected at landings and markets: The case of European megrims

Many marine stocks are endangered by inadequate or unreported exploitation, and mislabelling can enhance the problem. We focused this work on two morphologically similar marine species that are caught together in mixed fisheries, the European common megrim (Lepidorhombus whiffiagonis) and the four-spotted megrim (L. boscii). We sampled 239 megrim individuals directly from landings from five different points of Spain, the world's main consumer of megrim, and 264 megrims from five different markets. Samples were genetically analyzed and identified with a species-specific marker. We found that 40% of megrims were incorrectly labelled at landings, and this mislabelling error increased to 60% at markets, the highest values ever reported for fish and shellfish. In addition, although most landings across Europe (90%) were identified as L. whiffiagonis, genetic results showed that only 49% belonged to this species and the rest were L. boscii suggesting a unidirectional mislabelling. Erroneous identification of fish catches leads to inaccurate estimates of exploitation and, if prolonged over time, can contribute to the exhaustion of stocks and loss of genetic diversity. Our results highlight the urgency of a separate management plan for each megrim species in markets and the need to apply currently available molecular markers if visual methods are not good enough for species identification.