The efficacy of emamectin benzoate as an oral treatment of sea lice, Lepeophtheirus salmonis (Kroyer), infestations in Atlantic salmon, Salmo salar L.

Citation

Stone J, Sutherland IH, Sommerville C, Richards R & Varma KJ (1999) The efficacy of emamectin benzoate as an oral treatment of sea lice, Lepeophtheirus salmonis (Kroyer), infestations in Atlantic salmon, Salmo salar L.. Journal of Fish Diseases, 22 (4), pp. 261-270. https://doi.org/10.1046/j.1365-2761.1999.00176.x

Abstract
The efficacy of emamectin benzoate as an oral treatment of sea lice, Lepeophtheirus salmonis (KrÒyer), infestations in Atlantic salmon, Salmo salar L., was evaluated in a dose titration study and two dose confirmation studies. Replicated groups of salmon with induced infestations of sea lice were given emamectin benzoate on pelleted feed at doses of 0, 25, 50 and 100 μgkg-1 biomass day-1 for seven consecutive days. Sea lice were counted at 7, 14 and 21days from the start of treatment, and comparisons made with control fish given the same diet without emamectin benzoate. Total numbers of sea lice were significantly reduced at all doses in all three studies when compared to control fish. There was no significant difference between doses of 50 and 100μgkg-1, but the 50μgkg-1 dose resulted in significantly fewer lice than the 25μgkg-1 dose. Emamectin benzoate was highly effective in reducing numbers of preadult and adult lice and prevented the maturation of chalimus to motile stages. The optimum therapeutic dose was selected as 50μgkg-1day-1 for seven days. Treatment reduced the incidence of epidermal damage by sea lice and, in one study, survival of treated fish was 48% higher than in control groups. No fish mortalities or adverse effects were attributed to treatment with emamectin benzoate at any of the doses tested.

Journal
Journal of Fish Diseases: Volume 22, Issue 4

People

Professor Randolph Richards

Emeritus Professor, Institute of Aquaculture