While the exact contribution of anthropogenic impacts and changes in ocean-atmospheric conditions affecting the northern hemisphere eel species remains unclear, a combination of factors has resulted in declines in recruitment of Anguilla japonica (the Japanese eel), causing East Asian farms to seek alternative sources beyond species of local provenance ( 9 , 11 ). Along with other combined pressures, this has resulted in unsustainable exploitation of A. anguilla with recruitment declines of 90% since the 1980s ( 12 ). In 2007, European eel was listed on Appendix II of the Convention on International Trade in Endangered Species (CITES) ( 10 , 13 – 15 ). While not immediately threatened with extinction, Appendix II–listed species may become so without controls on international trade. Hence, import and export permits are required when Appendix II–listed species are moved across international borders. On the basis of not being possible to perform a nondetriment finding, a zero-import/export policy was imposed and all commercial trade of A. anguilla to and from the European Union was banned from 3 December 2010 onward ( 15 ). A. anguilla is currently assessed as “critically endangered” by the International Union for Conservation of Nature (IUCN) Red List ( 16 ), and illegal trade of A. anguilla is recognized as one of the most serious wildlife crime problems the European Union faces ( 17 , 18 ). Europol estimates that 100 MT (equal to approximately 300 million eels) were trafficked from Europe to Asia in the 2017/2018 glass eel catch season ( 19 ).

One of 16 anguillid eel species ( 1 ), the European eel (Anguilla anguilla) is a catadromous and panmictic freshwater eel whose continental nonbreeding range is distributed across Europe, North Africa, and Mediterranean Asia ( 2 ). The species is vulnerable to various potential threats at multiple developmental stages of its complex life history, which include habitat loss and modification, migration barriers, pollution, parasitism, fluctuating oceanic conditions, as well as exploitation ( 3 – 9 ). A. anguilla is commercially harvested across all continental stages of its life cycle, and juvenile glass eels are wild caught to “seed” farming operations in Europe and East Asia (to date, captive breeding has not been economically viable) ( 10 ).

International trade of European eel

Eel farming makes up 90% of eel production and relies heavily on wild-caught glass eels (10). Glass eels are a highly lucrative commodity; for example, 1 kg of European eel fry on the black market can contain up to almost 3500 individuals, sometimes fetching as high as EUR 6250 per kilogram in East Asia (18). While growth rates and market prices for species vary, the increase in biomass over a 2-year growth period has been found to be roughly 1000× and corresponds to a large return on investment (10, 18). The high-value trading associated with eel farming has inevitably attracted attention from criminal organizations, with reports of eel trafficking closely linked to criminal syndicates worldwide (2, 19, 20).

The European Union ban on European eel exports has preceded a shift in European eel exports coming from North African countries and also resulted in increased exploitation of other anguillid species in North America and the Indo-Pacific (13). Before the ban, 93 to 98% of live eels exported from North Africa were destined for European countries; following the ban, 91 to 93% of exports are now bound for East Asia (13). Although North African countries have their own policies regulating anguillid trade, there is evidence that the European Union ban can be circumvented by states within the range of the European eel but not subject to the European Union’s regulations to access European eel populations (13). Regardless, all European eel, whether originating from North Africa or Europe, would require the proper CITES permits and documentation when traded internationally (10, 13, 21). Despite regulations and increasing seizures in recent years, the illicit eel trade continues to pose challenges for enforcement (10, 21). Demand for eel is mostly from East Asia, and the Hong Kong Special Administrative Region is an important hub for regional glass eel trade through which Europe-Asia trafficking routes have been documented (10, 21–23). Illegally traded species can often evade customs inspection due to visual similarity between legal and illegal species, which present even greater challenges in identifying processed products (2). In both live and processed forms, European eel fry are extremely difficult to visually distinguish from other anguillids such as A. japonica and Anguilla rostrata (2), and DNA-based identification using molecular methods is required for prosecution in court (2). While A. japonica and A. rostrata are considered “endangered” by the IUCN Red List (24, 25), only A. anguilla is classified as critically endangered and listed in CITES Appendix II. As a result, A. anguilla can be laundered with legal products and transported across borders undetected unless identified by genetic tests, which—despite recent developments of improved rapid testing protocols (26)—are still limited by time and cost.

Data downloaded from the CITES trade database website (https://trade.cites.org, accessed 29 March 2019) show there were no declared instances of legal European eel meat importation into Hong Kong in 2017 or 2018. As there are no eel aquaculture facilities in Hong Kong, all live or processed eel products would have been imported from abroad. Although CITES permits are required, the Chinese government often does not report trade between Hong Kong and China to CITES, potentially obscuring the path of traded eels (2). The CITES Animal Committee identified issues with regard to countries reporting eel exports and imports to the CITES trade database and recommended amendments for the description of specimen codes to increase future reporting procedures and data quality (27). The CITES Conference of the Parties 18 (CoP18) further adopted Decision 63 that encourages eel range states (A. anguilla and other Anguilla species) to develop and implement measures to improve the traceability of eels in trade (28). While discrepancies between European, North African, and Asian CITES and customs trade data certainly exist (2), we focused our analysis on CITES trade reports as the Protection of Endangered Species of Animals and Plants Ordinance (Cap. 586, which governs the permit requirements of import/exports into and out of Hong Kong) is based on species listings in CITES Appendices (2). In addition, CITES trade data identify to the species level, while other databases such as United Nations Comtrade are not as specific, and, in some instances, Anguilla species are aggregated with other fish species such as carp and catfish (e.g., Harmonized Commodity Description and Coding System code 030439, which encompasses eight different genera). On the basis of the official CITES trade reports, it is expected that European eel products found in Hong Kong should be few to none.