Percussive stunning of Atlantic salmon (Salmo salar) and the relation between force and stunning

Evaluation of the efficacy of an automated percussive stunning system on immobilized harvest sized Atlantic salmon (Salmo salar) have been done. Percussive stun can be achieved by applying just one hammer stroke to the head. The proportion of fish stunned was significantly dependent on the applied force used in the system. Eye injuries as haemorrhaging and eye bursts increased with increased force in the range required for an effective stun. A hammer shaped cylinder proved to be most suitable for stunning salmonids, since spike or cone shaped hammers proved inefficient, due to the accuracy of the position of the blow. We conclude that percussive stunning promotes both welfare and efficiency in industrialized slaughter of salmonids.