European eel populations have declined by over 90% due to habitat loss, overfishing, and migration barriers, with fish passage systems offering a welfare and conservation intervention for this critically endangered species.
European eel welfare and conservation are deeply intertwined because the primary conservation problem — blocked migration — is also a welfare problem for individual eels. Eels attempting to pass dams and weirs become exhausted, injured on turbine blades, and die in large numbers during both upstream and downstream migration. Fish passage systems that allow safe passage simultaneously improve individual welfare and population conservation outcomes. The precautionary approach to harvesting a critically endangered species also reduces welfare costs by reducing the numbers captured and experiencing handling stress. This is a species where every individual matters for both conservation and cumulative welfare reasons.