Small fins, large trade: a snapshot of the species composition of low-value shark fins in the Hong Kong markets

The international fin trade is a major source of mortality for many threatened shark species but most of what it is known about this trade comes from assessments of large fins commanding high prices in trade hubs. There is growing international trade in 'small, low-value' fins in Southeast Asia, which are used for inexpensive shark fin soup products. These fins could be derived from small species, juveniles of large species, or a combination of both. Resolving the species identification of these small fins has important conservation implications, because large sharks tend to be more vulnerable (VU) to overexploitation than small ones. Here we describe the first species-specific assessment of the small, low-value fins in the shark fin retail markets of Hong Kong. A total of 475 randomly collected samples were genetically identified using a portion of the cytochrome oxidase I, revealing at least 29 species. Around a third (34.5%) of the species found are in threatened International Union for the Conservation of Nature Red List categories, and 21.2% of the samples were from four species listed on Appendix II of the Convention on International Trade in Endangered Species (CITES). The size of the analyzed fins and the species composition found suggests that small fins come from a combination of small (62.9 %) and large (37.1%) species, with the majority of small fins coming from suspected juveniles of large species. We suggest the sources of most of these fins are likely to be multi-species fisheries in shallow, coastal habitats used by large species and also occupied by small species. Our results represent the first step to better understand the trade in small shark fins on a species-specific basis and highlight the need for market surveys and increased inspection of this fin category at border control check points for CITES-listed species.