R. Watson, (1977), M.Sc., University of Manitoba, Winnipeg, Manitoba, Canada.

Intensity, prevalence and dominance fo parasites, as well as the diversity and similarity of the parasitofauna of the lake whitefish (Coregonus clupeaformis Mitchell), the lake herring or cisco (C. artedii Leseur) and the northern pike (Esox lucius L.) were studied at Southern Indian Lake (S.I.L.), Manitoba. Amphipod vectored parasites were less important and copepod vectored parasites were more important in S.I.L. than reported for other systems. Abundance of parasite species was altered by host age and season. Geographical location affected the ranking of parasite abundance but no differences in parasite abundance was observed in different sexed fish. Plerocercoids of Triaenophorus crassus Forel in whitefish and cisco, and Diphyllobothrium sp, in pike exhibited nonrandom distribution in host musculature and could not be explained entirely by relative muscle mass or asymmetry of fish intestinal tracts. Condition of cisco and whitefish was modified by presence of T. crassus plerocercoids. This study presents data prior to impoundment and diversion of current, and predicts changes in the parasitofauna of these fish species.