DNA barcoding has revealed that more than half of the dried shark fins and gill plates being traded originate from species classified as Endangered or Vulnerable by the IUCN. The study, published in Scientific Reports in August, was led by Dirk Steinke from the University of Guelph, with Mahmoud Shivji from the Guy Harvey Research Institute and Save Our Seas Shark Research Center at Nova Southeastern University and colleagues. While a quarter of sharks and rays are considered threatened, the demand for products in the form of fins, meat, liver, oil and gill plates remains a significant challenge to managing their populations. Commercial trade in several species is banned. However, new evidence shows that this hasn’t stopped people from buying and selling their fins and gill plates.

Understanding the population status of elasmobranch species around the world helps to inform management decisions. This requires improvements to current catch data, with one of the major challenges being the accurate identification of species that look similar, or whose body parts have already been processed. Dried fins and gill plates lack any clear features that can help researchers to confidently identify their species of origin. This study used DNA barcoding to identify species from genetic material obtained from dried fins and gill plates collected in Canada, China and Sri Lanka.

DNA barcoding is an exciting development that improves the resolution of elasmobranch identification, with special relevance for detecting whether products originate from legal or illegally imported species. Seventy-one fins and 53 gill plates were analysed and matched to 20 shark and five ray species; 56% of these species are on the IUCN Red List as Endangered or Vulnerable. The number of species considered vulnerable increased to 80% when those classified as Near Threatened were included. Twelve of these species have been approved in 2017 for listing on the Convention on International Trade in Endangered Species of Fauna and Flora (CITES) appendices: seven shark species and all five rays are banned from trade under this listing. Samples were collected in 2012, and while trade bans for most of these species came into effect between 2014 and 2017, some samples came from species like the whale shark, which had protected status and was banned from trade at the time of sampling. As the researchers write in their paper, ‘This work demonstrates the importance of market surveillance as a conservation countermeasure that would benefit from large-scale and long-term monitoring.’