DNA Zip‐coding: identifying the source populations supplying the international trade of a critically endangered coastal shark

There is an urgent need for population‐specific trade information for overexploited sharks, as international trade regulations are becoming an important tool for their conservation [i.e., listings on the Convention on International Trade in Endangered Species (CITES)]. We tested a genetic stock identification (GSI) workflow to quantify the relative contributions of different source populations of the CITES‐listed scalloped hammerhead shark Sphyrna lewini to international trade hubs for products such as dried fins. We grouped published mitochondrial control region sequences from wild‐captured sharks sampled in 15 locations into 9 differentiated populations that provide broad coverage of the species global distribution. GSI simulations established that these populations are highly identifiable and we trialed this approach to assess the provenance of processed fin trimmings collected randomly from the retail market of Hong Kong, one of the world’s largest shark fin trade hubs in 2014–2015 (N = 72). In this pilot survey, we found over 75% of scalloped hammerhead fin trimmings came from two Pacific Ocean populations, but mostly from the Eastern Pacific (61.4%, of all trimmings; se 7.1%) where this species is listed as ‘Endangered’ under the United States Endangered Species Act. Six of the nine populations were found in this sample of the market, indicating near global sourcing of scalloped hammerhead fins in Hong Kong. We suggest technical and sampling considerations for employing GSI at fin trade hubs in the future to investigate regional sourcing of scalloped hammerheads and other coastal sharks in international trade. Random GSI in trade hubs could revolutionize our understanding of global shark trade dynamics and provide critical information required to effectively implement shark fisheries management and trade restrictions. Sourcing wildlife products in trade is an important component of emerging strategies to combat trafficking. We used a global genetic dataset for critically endangered scalloped hammerhead sharks to trace fins in the Hong Kong market back to the place where the sharks were caught. We found fins from this species from all over the world in Hong Kong but most came from the west coast of Central and South America, indicating that supply chains for shark fins originating there are in dire need of interventions to better control trade of this species.