The European eel is critically endangered with population indices at less than 10% of 1980 levels. Their extraordinary life cycle from Sargasso Sea to European rivers and back makes conservation and welfare exceptionally complex.
Migrating silver eels passing through hydroelectric turbine blades suffer traumatic injuries causing death or severe wounding. Glass eels caught for aquaculture restocking are subject to significant handling and transport stress. Electric fishing used for population surveys causes stress responses and, at excessive amperages, physical injury. Migratory fish blocked by river barriers experience frustration and energy expenditure without reproductive success. The cumulative welfare harm of river fragmentation is multiplied across thousands of individual eels attempting migrations each autumn.