The range of the European eel Anguilla anguilla includes most of Europe, North Africa and western Asia. The species has declined dramatically and in 2007 it was included on Appendix II of CITES, regulating all international trade. In 2008 it was categorized as Critically Endangered on the IUCN Red List. In 2010 the EU banned all imports and exports of European eel, but regulated trade within the EU remained possible. Brexit—the withdrawal of the UK from the EU—means that as of 1 January 2021 three of the four nations that make up the UK are no longer part of the EU single market. Northern Ireland is the only nation still included. The most important wild-caught eel fisheries in Europe are on Lough Neagh in Northern Ireland; c. 300 t is caught annually and 80% of this is exported to the Netherlands to meet the demand for smoked eel. The Lough Neagh fishery depends on restocking with glass eels (juveniles) in the lake as recruitment is insufficient to meet the demand for fully grown eels. In the past decades, 1–2 t of glass eels were supplied annually from England and Wales. Currently there is no legal glass eel fishery in the Republic of Ireland and Northern Ireland that could meet this requirement. With the three UK nations having left the EU single market there is no legal option for the UK glass eel fisheries to export to Lough Neagh or any other part of the EU single market, as the EU does not allow the import of eels from third countries, until at least the end of 2021.

For the Lough Neagh eel fisheries to remain viable, up to 2 t of glass eels will have to be imported from other parts of the EU. France and Spain are the most likely countries for sourcing these imports. If this materializes then the trade of wild-caught eel from Lough Neagh to the Netherlands can continue.

The UK glass eel fishery will lose almost all of its legal market supplying Lough Neagh and other parts of the EU for farming and restocking purpose. In the absence of significant domestic eel farming this leaves the glass eel fishers without a market. Demand for glass eels is high outside the EU, in particular in China and other parts of East Asia. This demand has been met in part by a substantial illegal trade, so much that the illegal eel trade from the EU is its most important illegal wildlife trade in terms of monetary value (glass eels are traded for c. EUR 900/kg on the illegal European market). We are concerned that an oversupply of glass eels in the UK and the high demand in East Asia will lead to an increase in illegal trade between these two regions.