Effects of stunning/slaughtering methods in rainbow trout (Oncorhynchus mykiss) from death until rigor mortis resolution

Abstract The effects of stunning/slaughtering methods (carbon monoxide asphyxia, CO; electroshock, E; asphyxia in the air, A) were studied in rainbow trout kept in freshwater at 12 °C. The fish were analysed for blood parameters, rigor mortis evolution, fillets shape changes over 48 h, and ATP depletion and Adenylate Energy Charge (AEC) in muscle immediately after death. Treatment A was most stressful giving the lowest pH values during rigor evolution, the highest concentration of lactate (6.31 mM) in plasma and the lowest AEC values in the muscle. None of the three-stunning/slaughtering methods affected perimeter, length and height of the fillets, with exception for the area at 24 h and 48 h post mortem , which was significantly reduced by CO treatment (CO  Statements of relevance 1. The application of CO as slaughtering/killing method on rainbow trout, focusing on the effects produced in the pattern of some analytical parameters during the first period post mortem 2. The use of carbon monoxide for killing fish has been only recently experimented and only in Atlantic salmon. 3. Improve the knowledge about the use of CO, due the scarcity of information in scientific literature