摘要 : The purpose of this study was to determine the effect of clove oil (4.0 mg L^-1) sedation, compared with non-sedation, on the primary (plasma cortisol), secondary (osmoregulation) and tertiary (mortality) stress response... 展开 The purpose of this study was to determine the effect of clove oil (4.0 mg L^-1) sedation, compared with non-sedation, on the primary (plasma cortisol), secondary (osmoregulation) and tertiary (mortality) stress responses in Atlantic salmon smolts during transport and transfer to sea. Clove oil sedation during on- and off-loading sufficiently reduced the primary stress response to lower mortality (2.1%) during transfer to sea compared with unsedated fish, which experienced a mortality rate above 12.2%. The unsedated fish experienced an acute mortality that stabilized only 6 days after the transport. None of the secondary stress responses measured in this experiment could contribute towards explaining this phenomenon, with the possible exception of plasma magnesium (Mg²⁺). Plasma Mg²⁺ differed between the groups; while plasma Mg²⁺ in the clove oil sedated group returned to pre-stress levels 72 h after transport, the unsedated group showed no such recovery even 1 week after transport, which may indicate a disturbance in the hydromineral balance, and provides a plausible explanation for the delayed mortality in this group. Eugenol-based anaesthetics appear to be promising as a stress-reducing sedative for Atlantic salmon smolts, and, if used properly, this chemical could improve animal welfare and survivability during and after common aquaculture-related incidents. 收起