Handling stress and water quality during live transportation and slaughter of Atlantic salmon ( Salmo salar)

Atlantic salmon ( Salmo salar), mean weight 5.1 kg, were transported live for 1.5 h by a well-boat (fish density 125 kg m −3) from the seacage to a fish processing plant and then kept in the well-boat for 4 h prior to slaughter. Anaerobic white muscle activity due to handling stress during fish loading at the cage, after shipment immediately before slaughter, and after the fish had passed the slaughter line, was evaluated using high-energy phosphates and IMP, the [ATP:IMP] ratio, adenylate energy charge together with pH and redox potential measured directly in the muscle. Water quality parameters, pH, salinity, temperature, dissolved oxygen, carbon dioxide, total carbonate carbon, total alkalinity, ammonia and ammonium were monitored at the cage, during shipment, and in the carbon dioxide anaesthesia tank during commercial fish slaughter. No dramatic effects of handling stress were found, indicating that transport and slaughtering did not have an adverse effect on flesh quality. The results were explained by the ability of the well-boat to maintain good seawater quality during transport, to a quick bulk netting of the fish from well-boat to the slaughter line and to an efficiently run carbon dioxide anaesthesia-tank that minimised struggling prior to killing.