The Succession of Generations and Growth of the Caligid Copepods Caligus Elongatus and Lepeophtheirus Salmonis Parasitising Farmed Atlantic Salmon Smolts (Salmo Salar L.)

Infestation of cage cultured Atlantic salmon by the external parasitic copepods Caligus elongatus (Nordmann) and Lepeophtheirus salmonis (Kröyer) is a serious cause of loss of production in the commercial sea water culture of this species. The copepods feed on the mucus, skin and blood of their hosts (Kabata, 1974; Brandal et al., 1976) causing irritation and lesions. Loss in production due to infestation by lice occurs directly by the mortality of fish from osmotic shock and indirectly from a probable reduction in growth, from secondary infections such as vibriosis (Wootten et al., 1982) or by increasing vulnerability to ultraviolet radiation damage (McArdle & Bullock, 1987).