European eels face critically endangered status, and aquaculture operations depend entirely on wild-caught glass eels, raising welfare and conservation concerns for this declining species.
Eel aquaculture sits at an acute conservation-welfare intersection: every glass eel used in aquaculture is a wild-caught individual whose removal reduces natural recruitment to an already critically depleted population. The welfare of the individual eels in captivity — stress during capture, high-density holding, feeding adjustment from natural to commercial diets — is compounded by the population-level harm of removing individuals from a species in severe decline. Welfare science for eels is underdeveloped because their nocturnal, fossorial behavior makes observational welfare assessment difficult. The precautionary case for phasing out eel aquaculture until sustainable captive breeding is achievable is strong on both conservation and welfare grounds.