Coupled DNA barcoding and mini-barcoding approaches expose illegal trade of endangered elasmobranchs from the Southwestern Atlantic

Abstract

Sharks and rays are globally exploited, with their vulnerability to overfishing leading to many species being classified as endangered. In this study, we combined DNA barcoding and mini-barcoding approaches to enhance the detection of elasmobranch species in processed products. Over five years along the Brazilian coast a total of 122 samples were collected, including fresh fillets and fins, and cartilage capsules from distinct brands. By employing multiplex PCR and sequencing of both long and short fragments of the cytochrome c oxidase subunit gene, we identified 21 species, from five orders and nine families of sharks and rays combined. Sixteen of these species are under some degree of threat, including five critically endangered species from families Rhinobatidae, Sphyrnidae, and Carcharhinidae, listed by the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). Many shark cartilage capsules lacked proper species labeling, with one sample containing a CITES-listed species, highlighting the urgent need for stricter law enforcement. Notably, this study expanded the use of mini-barcoding and Sanger sequencing, enabling the identification of seven species previously undetectable using this strategy. This study demonstrates the effectiveness of a cost-efficient DNA-based approach for monitoring elasmobranchs in commercial products, making a novel contribution to conservation efforts aimed at safeguarding their threatened biodiversity.