Effectiveness of tail-first dry electrical stunning, followed by immersion in ice water as a slaughter (killing) procedure for turbot (Scophthalmus maximus) and common sole (Solea solea)

摘要

To protect the welfare of fish at slaughter, these animals should be rendered unconscious and insensible prior to killing. Furthermore, the state of unconsciousness must be long enough to allow killing without recovery. The objective of this study was to determine the stunner settings for effective tail-first dry electrical stunning of turbot (Scophthalmus maximus) and common sole (Solea solea). The fish were separated in two batches (B1 and B2). The turbot and sole in B1 were subjected to a short tail-first stun lasting for 1 s and after 1 min of recovery to a second, longer (20 s) stun. The fish in B2 were exposed to a single long (20 s) stun, which was tail-first in sole, but headfirst in turbot. The short stun was applied to verify that the loss of consciousness was instant (i.e. within 1 s), whereas the long stun (followed by immersion in ice water) was performed with the aim of showing that it is feasible to kill the fish without recovery. Loss of consciousness and sensibility were assessed using electrophysiological (EEG and ECG) and behavioural parameters.