The physiological response of Atlantic salmon (Salmo salar) to sea lice (Lepeophtheirus salmonis) infection and the effects of hydrogen peroxide treatment

The physiological response of Atlantic salmon to the stress caused by sea lice infection was examined. Fish were infected with copepods, resulting in an average infection of 106 sea lice per fish (range: 15–285). The infected salmon were sampled 6 times over a 29 d time period and blood samples were measured for cortisol, glucose, electrolytes, T3 and T 4 concentrations, as well as hematocrit.

Hydrogen peroxide has been used as a method for sea lice removal. Although it has been demonstrated to remove sea lice relatively effectively, it was necessary to focus on its impacts on the host salmonid.

Short-term exposure to a hydrogen peroxide bath (>750 ppm) has been shown to effectively remove sea lice. Smoltified salmon were exposed to four possible treatments (0, 1000, 1250, and 1500 ppm. hydrogen peroxide) for 20 min at 10°C. Blood samples were taken for cortisol, glucose, electrolytes, and protein concentrations, as well as hematocrit. Trial 1 examined both the acute and chronic stress response of salmon to hydrogen peroxide exposure. Trial 2 was conducted using S1 and S2 fish to determine if the stress response which resulted from hydrogen peroxide exposure would increase susceptibility of the fish to sea lice infection. (Abstract shortened by UMI.).