Lepeophtheirus salmonis (Copepoda: Caligidae) on farmed salmon in Ireland

The investigation of specific characteristics of Lepeophtheirus salmonis populations on farmed salmon was made possible by the examination of the parasite infestation parameters of regular non destructive samples taken for up to six years in five bays. Perennial persistence of seasonal patterns of infestation as exhibited by intensity, prevalence and abundance was examined. Site specific characteristics were detected which appeared to be independent of inter-annual variations. Seasonal variations in individual lice size and fecundity, and temporal variation in population dynamics on the farmed fish in the five bays are considered in the context of the not inconsiderable changes in husbandry and lice control practices which have been introduced in the industry over the six year period.