What'S In A Name? Phylogenetic Species Identification Reveals Extensive Trade Of Endangered Guitarfishes And Sharks

Fishing has a major impact on the biodiversity of elasmobranchs, a diverse and ancient group of fish. The illegal trade of products derived from endangered species is widespread and many times concealed by both deliberate and inadvertent mislabeling. In groups where data is sparse, such as guitarfishes, it is unknown which species are at a higher risk of extinction due to illegal trade. Brazil is currently one of the world's largest market for elasmobranch products, but it is uncertain whether the current regulatory measures are effective across all commercial sectors. Here, we applied molecular phylogenetics to identify the species sold as elasmobranchs in Rio de Janeiro. Products labeled as "shark", "ray" and "guitarfish" were sampled from fishmongers, supermarkets, restaurants and street markets (n = 221). Over 60% of the samples were derived from threatened species, reaching 90% in guitarfish and 100% in ray products. The endemic and critically endangered Pseudobatos horkelii was the only authentic guitarfish among all samples labeled as such (n = 75), all others were identified as threatened/endemic rays (Atlantoraja castelnaui, A. cyclophora) or sharks (Squatina guggenheim, S. occulta). S. guggenheim was also detected among the products labeled as "sharks" (n = 113), as were five other endangered shark species: Carcharhinus falciformis, C. signatus, Isurus oxyrhinchus, Sphyrna zygaena and S. lewini. While no mislabeling was observed in supermarkets, the prevalence was high in local trade, indicating that regulatory and awareness-raising measures must be adapted to this economically and socially important sector.