European and Japanese eels cannot be bred in captivity — all farmed eels begin as wild-caught elvers. This creates a double welfare problem: stress during wild capture and transport, and poorly understood needs during grow-out.
Eel elver welfare is doubly problematic because wild-caught animals experience the stresses of capture and transport before entering farm systems. Glass eels are tiny and fragile; handling and density during transport causes measurable mortality. In grow-out systems, high stocking densities promote aggression and size-sorting, which are stressful. The ecological crisis around wild eel populations adds a conservation dimension that complicates simple welfare analysis — reducing wild capture pressure might require completely different production models. Slaughter welfare for eels is a major unresolved issue; the traditional practice of killing eels by live cutting or exposure to salt is acutely painful given documented nociceptive responses. Some producers have adopted percussive stunning before slaughter, but this is far from universal. Regulatory attention to eel welfare has increased in the EU, but enforcement gaps remain significant.