TWENTY-THIRD ANNUAL EASTERN FISH HEALTH WORKSHOP JOHN CARVER INN, PLYMOUTH, MA 30 MARCH - 2 APRIL, 1998 The Effects Of Sea Lice, Lepeophtheirus salmonis, On the Stress Response Of Atlantic Salmon, Salmo salar. Joanne Bowers, John Burka, Ahmed Mustafa, David Speare, Gary Conboy. Department of Anatomy and Physiology, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, P.E.I. The sea louse, Lepeophtheirus salmonis, is an ectoparasite of Atlantic salmon capable of causing severe damage, often resulting in the death of the animal due to increased susceptibility to other infections. This study was conducted to examine the impact lice have on the stress response of salmon. Ovigerous lice were obtained from aquaculture sites in Maine and egg strings were removed from the females to allow hatching in the laboratory. Smoltified salmon, with a mean weight of 680 g, were acclimated in 30 ppt seawater and exposed to high levels of lice infestation 12 days post-hatch. The number of lice per fish ranged from 15 to 285, with a mean of 106. The salmon were sampled at weekly intervals and examined for alterations in the primary and secondary stress indicators, i.e. cortisol, glucose, T3 and T4. The number of lice per fish was recorded and damage levels were noted. The results were examined for correlations between stress indicators, number of lice per fish, life stage of the lice, and overall health of the salmon. It was observed that the presence of L. salmonis elevated the stress responses, with cortisol levels rising significantly at day 21 post-infestation. This corresponded with the development of the lice to the fourth chalimus stage, therefore suggesting sea lice becomes more detrimental at later life stages. Glucose levels also demonstrated a significant increase due to the presence of the sea lice, while T3 and T4 levels remained relatively unaffected. The abundance of lice did not seem to affect the overall health of the animal, as condition factor did not correlate with the number of lice. Supported by a grant from the NSERC/NRC Partnership Program   Return to 23rd Annual Eastern Fish Health Workshop Return to Leetown Science Center Home Page