New study reveals endangered shark species sold in UK food market.
Photo by David Clode (Unsplash)
by Anton Kuech
Sharks and rays belong to the elasmobranch subclass, identified as one of the most threatened vertebrate groups, with a major international study in 2014 estimating that around one-quarter of species are threatened, according to the IUCN Red List criteria. Population depletion is largely attributed to overfishing, whereby slow-growing, large-bodied, shallow-water species are particularly vulnerable to targeted fishing.
Shark population declines have increased global awareness of the issue and have led to 12 species being added to Appendix II of the Convention on International Trade in Endangered Species of Fauna and Flora (CITES). CITES listings regulate trade on these endangered species, forcing exporting countries to prove that the trade of the exported species will not impact the wild populations.
Additionally, the European Union (EU) regulates fisheries by setting Total Allowable Catches (TACs) to zero, and thus, prohibiting landings of endangered species.
Researchers from the University of Exeter have investigated fish products to verify if prohibited shark species are entering the UK food market. The study used cytochrome oxidase I (COI) DNA barcoding, a taxonomic method used to identify a sample from an organism to species level.
117 tissue samples were collected, including fish and chip takeaways, fishmongers and shark fins from wholesalers. Fishmongers showed a high variability of products, whereby most species were identified as local UK shark fauna, not supporting the idea of a global supply chain. In contrast, fish and chip takeaways were dominated by sales of spiny dogfish, a species identified as globally threatened (IUCN Red List) and set at zero TAC in the EU. The authors argue that a complex, international supply chain governs trade in the fish and chip takeaways. The fin samples were identified as a range of threatened and endangered species, not resident in UK waters, suggesting sales of prohibited sharks within Europe. This included the identification of the endangered and CITES-listed scalloped hammerhead. Dr Andrew Griffiths from the University of Exeter stated: “The discovery of endangered hammerhead sharks highlights how widespread the sale of declining species really is, even reaching Europe and the UK.”
“The discovery of endangered hammerhead sharks highlights how widespread the sale of declining species really is, even reaching Europe and the UK.”
Additionally, the authors of the study identified misleading labelling of shark products, in which “umbrella” labels were applied to disguise the actual shark species. Cathy Hobbs, the first author of the study, stated: “It’s almost impossible for consumers to know what they are buying. People might think they’re getting a sustainably sourced product when they’re actually buying a threatened species.”
In sum, a diverse pattern of species utilisation was identified, whereby fish and chip takeaways were found to largely include the threatened spiny dogfish and fin samples were identified to be from sharks of high conservation concern. Shark declines have been identified globally, with, for example, shark numbers off the coast of Queensland, Australia, having declined by more than 90% in the past half-century. Senior author Andrew Griffiths, from the University of Exeter, concluded: "Sharks typically take a long time to reach sexual maturity and, once they do, produce relatively few young -- at least in comparison to most fish that are commercially caught. This makes them very vulnerable to overfishing as they simply cannot replace themselves very quickly.”
