Metazoan parasite community structure of sea trout on the west coast of Ireland

A total of 129 sea trout smelts from 10 locations on the west coast of Irel and were examined for metazoan parasites. Of 11 species identified only fou r had a prevalence >20%. Two species Hysterothylacium aduncum and Hemiuris communis have a confirmed marine origin; Eubothrium crassum has been shown to exist in both the sea and fresh water. The remaining species were fresh water. Overall the parasite community was dominated by autogenic species wi th only Diphyllobothrium dendriticum having allogenic transmission. Infraco mmunity values for mean species richness, and Brillouins index of diversity were low, indicating the presence of an impoverished helminth community wi th little potential for interspecific interaction. The relationship between marine helminths and sea lice was also examined. (C) 1999 The Fisheries So ciety of the British Isles.