The welfare of rainbow trout at slaughter depends critically on the stunning method used. Understanding effective and humane slaughter techniques is essential for improving fish welfare at end of life.
At the point of slaughter, fish welfare depends entirely on the effectiveness of the stunning method used. Carbon dioxide exposure causes a prolonged, distress-inducing loss of consciousness as fish show vigorous avoidance behaviour and clear signs of respiratory distress. Ice slurry alone causes gradual hypothermic immobility without rapid loss of consciousness. Effective electrical stunning renders fish immediately insensible, providing the most humane outcome when applied correctly. However, equipment maintenance, operator training and stocking density during the slaughter process all affect whether the stated method actually achieves effective stunning in practice.