The European eel (Anguilla anguilla) is Critically Endangered, yet significant numbers are captured as glass eels (elvers) for aquaculture stocking. Their complex lifecycle — from Sargasso Sea spawning to European rivers — combined with their unique biology creates specific welfare challenges in both fisheries and farming.
Glass eel capture at estuaries involves concentration by tidal traps or dipnet fisheries and holding in high-density containers. Transport mortality can reach 10-20% without careful dissolved oxygen management. Eels in aquaculture systems show circular swimming stereotypies at high stocking densities, indicating chronic stress. Pre-slaughter welfare is poorly developed for eels: live salting and skinning of eels for traditional European markets causes prolonged distress, and stunning methods are not standardised. The wider welfare concern is population-level: each eel removed for aquaculture is one fewer potential spawning adult in a Critically Endangered population.