European and Japanese eels are farmed under intensive conditions that raise significant welfare concerns, compounded by the fact that their reproduction cannot be controlled in captivity, making all farmed eels dependent on wild-caught juveniles.
Eel welfare combines conservation concerns with direct individual animal welfare issues in a particularly challenging way. The complete dependence on wild-caught juveniles means that eel farming is inseparable from ongoing wild population depletion — the welfare of billions of wild-born animals is tied to every farmed eel. In intensive aquaculture ponds and raceways, eels are held at densities that prevent normal behaviour, causing chronic stress reflected in elevated cortisol levels. As nocturnal, benthic animals that naturally hide in substrate crevices, the barren concrete or plastic environments of intensive farms deny fundamental behavioural needs. Their resistance to death creates severe slaughter welfare problems: eels remain conscious and responsive for extended periods when killed by conventional methods, and inhumane slaughter (being skinned or cut alive) continues in some contexts. Percussive stunning followed by spiking or electrical stunning are the most humane methods, but are not universally applied.