Multiple fish stunning methods exist for aquaculture use. Their effectiveness, species applicability, and welfare implications differ significantly. Best practice varies by species and context.
Fish stunning efficacy is critical because inadequate stunning or stunning that fails to maintain unconsciousness through bleeding causes avoidable suffering. Percussive stunning is simple, cheap, and effective for salmonids but requires skill to achieve consistent results. Electrical stunning is consistent when calibrated correctly but requires species-specific parameters. CO2, despite widespread use, causes significant distress during induction. Species differences in anatomy and physiology mean stunning parameters cannot be directly transferred between species. The most welfare-positive slaughter combines effective stunning with immediate bleeding or spiking to prevent recovery of consciousness.