The shark fin trade is a major driver of shark exploitation in fisheries all over the world, most of which are not managed on a species-specific basis. Species-specific trade information highlights taxa of particular concern and can be used to assess the efficacy of management measures and anticipate emerging threats. The species composition of the Hong Kong Special Administrative Region of ChinaPalabras Clave: ADN, Asia, ciencias forenses, conservación, manejo de pesquerías, mercado de vida silvestre

Trade-driven overexploitation threatens many sharks. Twelve of the world's most vulnerable shark species have been listed on the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) to regulate internationally traded products such as meat and dried fins. CITES records indicate that Hong Kong was the world's top legal importer of dried fins from listed sharks in 2015 (N = 8 species at that time), but traded a relatively small volume, with a few partners, in a small number of shipments (16). In contrast two CITES Appendix II listed hammerheads were consistently the fourth and fifth most common species (out of >80) in processed fin trimmings (N = 9,200) collected randomly from the Hong Kong retail dried fin market from February 2014 to December 2016 and were found in 100% of sampling events and in 66% of sampled retail vendors. This difference, and the fact that exporting nations previously known to land these species were not among those to report trade to CITES, suggest that listed species were often imported without CITES documentation in 2015. There are a number of incentives for trade hubs to meet their obligations to this treaty, which they could achieve by scaling up monitoring capacity and increasing inspection efficiency. K E Y W O R D SCarcharhinus falciformis, CITES enforcement, shark conservation, shark fin trade, sphyrna lewini, sphyrna zygaena, wildlife forensics

Protecting sharks from overexploitation has become global priority after widespread population declines have occurred. Tracking catches and trade on a species-specific basis has proven challenging, in part due to difficulties in identifying processed shark products such as fins, meat, and liver oil. This has hindered efforts to implement regulations aimed at promoting sustainable use of commercially important species and protection of imperiled species. Genetic approaches to identify shark products exist but are typically based on sequencing or amplifying large DNA regions and may fail to work on heavily processed products in which DNA is degraded. Here, we describe a novel multiplex PCR mini-barcode assay based on two short fragments of the cytochrome oxidase I (COI) gene. This assay can identify to species all sharks currently listed on the Convention of International Trade of Endangered Species (CITES) and most shark species present in the international trade. It achieves species diagnosis based on a single PCR and one to two downstream DNA sequencing reactions. The assay is capable of identifying highly processed shark products including fins, cooked shark fin soup, and skin-care products containing liver oil. This is a straightforward and reliable identification method for data collection and enforcement of regulations implemented for certain species at all governance levels.

Species-specific monitoring through large shark fin market surveys has been a valuable data source to estimate global catches and international shark fin trade dynamics. Hong Kong and Guangzhou, mainland China, are the largest shark fin markets and consumption centers in the world. We used molecular identification protocols on randomly collected processed fin trimmings (n = 2000) and non-parametric species estimators to investigate the species composition of the Guangzhou retail market and compare the species diversity between the Guangzhou and Hong Kong shark fin retail markets. Species diversity was similar between both trade hubs with a small subset of species dominating the composition. The blue shark ( Prionace glauca ) was the most common species overall followed by the CITES-listed silky shark ( Carcharhinus falciformis ), scalloped hammerhead shark ( Sphyrna lewini ), smooth hammerhead shark ( S. zygaena ) and shortfin mako shark ( Isurus oxyrinchus ). Our results support previous indications of high connectivity between the shark fin markets of Hong Kong and mainland China and suggest that systematic studies of other fin trade hubs within Mainland China and stronger law-enforcement protocols and capacity building are needed.

One third of chondrichthyan species (sharks, rays, and chimeras) are threatened with extinction, mainly due to unsustainable fishing. Large accessible international markets for meat and luxury products like dried fins can help drive overfishing by encouraging targeted capture or retention of high-value export species. If this is common, then species in international trade could have heightened extinction risk. Here, we examined the species composition of the Hong Kong shark fin market from 2014 to 2018, finding that traded species disproportionately occur in threatened categories (70.9%) and all premium value species are threatened. A small number of cosmopolitan species dominate the trade, but noncosmopolitan coastal species are still traded at concerning levels given their limited distribution. These coastal species are not generally subject to retention prohibitions, fisheries management, or international trade regulations and without management many could become extinct. The conservation potential of international trade regulations alone for coastal chondrichthyans depends on the extent to which overfishing is driven by export markets; socioeconomic studies of coastal fishing communities are needed to make this determination. Nonetheless, adding international trade regulations for more coastal shark species that are in the fin trade could prompt broad engagement with overfishing in nations lacking effective management.

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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.

Fins from highly mobile shark species entering large shark fin trade hubs can originate from various geographical locations and stocks. Tracing fins from internationally regulated species to their starting point in the supply chain can have important implications for the monitoring and enforcement of international laws intended to protect threatened shark species. Here we use pelagic thresher shark Alopias pelagicus fin samples (N = 86) collected during a 4‐year period (2014–2017), and phylogenetic analyses, using the cytochrome oxidase I (COI), to determine the relative contribution of this species to the two largest shark fin trade hubs in the world, Hong Kong and Guangzhou, mainland China. Our results suggest that the Eastern Pacific is a major starting point of the international supply chain of pelagic thresher shark fins, contributing 84.9% of the analyzed market‐derived fin samples. We suggest that capacity building investments are needed in Eastern Pacific countries to increase the efficiency of border control inspections and improve the enforcement of international trade regulations for this threatened shark species. Our study highlights the utility of combining population genetics data and large‐scale market surveys to trace wildlife products back to the starting point in the supply chain and support the assessment of emerging management and conservation measures for exploited sharks.