For R-eel?! Investigating international sales of critically endangered species in freshwater eel products with DNA barcoding

The growing popularity of Japanese cuisine worldwide has caused an increasing demand for freshwater eels (family Anguillidae), usually termed 'unagi' and commonly utilised in sushi and donburi dishes. The trade of the Critically Endangered European eel (Anguilla anguilla) is now restricted and this has resulted in illegal trade. Here, DNA barcoding was used to identify the species of eel sold in processed eel products worldwide, including a focus on Europe and North America. For the first time, traditional jellied and stewed eel products from the UK are also barcoded. A total of 114 novel samples were analysed alongside previously published data to evaluate differences in species composition between locations, over time and in unagi versus more traditional UK eel products. The results revealed more European eel in East Asia than in Europe and more Japanese eel (Anguilla japonica) in the UK than East Asia - demonstrating a stark contrast between the native species and those commonly on sale (although variation in product type and eel recruitment influence this). This suggests thousands of food miles are potentially hidden in unagi products. Considering the limitations on export of the European eel, the numbers identified in products outside of its natural range bring into question the legality of supply. An increased prevalence of endangered American eel (Anguilla rostrata) was also shown globally. Future efforts should focus on implementing robust traceability systems, including using genetic methods, to deter illegal trade within the industry.

Automated summary

The growing popularity of Japanese cuisine worldwide has resulted in a higher demand for freshwater eels (family Anguillidae). With the limitations on export of the endangered European eel, illegal trade has emerged. This study used DNA barcoding to identify eel species in processed eel products globally, revealing a contrast between native species and those commonly sold.