Humane Slaughter of Carp - A Comparison between Three Stunning Procedures

Fish welfare at slaughter is an area of considerable scientific and commercial importance during the last decade. The aim of this study was to evaluate the effect of three stunning procedures on stress and meat quality of common carp. The experimental fish were separated in three groups and stunned by percussion (Group PS), electricity (Group ES) or asphyxia (Group AS), followed by decapitation. Blood cortisol and glucose concentrations were measured as stress indicators, whereas drip loss was used as meat quality parameter. The lowest glucose concentration (3.86 +/- 1.26 mmol/L) and drip loss (2.02 +/- 0.42%) were observed in Group PS. On the contrary, Group AS showed the highest results (11.34 +/- 3.07 mmol/L and 3.22 +/- 0.75% for blood glucose and drip loss, respectively), whereas the electrically stunned carp took an intermediate position (6.05 +/- 1.29 mmol/L and 2.29 +/- 0.43%). We conclude that percussive stunning leads to considerable reduction of stress at slaughter and better meat quality (lower drip loss), whereas asphyxia is unacceptable method due to the strong stress reaction and increased drip loss. Electrical stunning can be an effective method for stunning carp, but requires improvements of the electrical device to eliminate the repeated current application.