HELMINTH-PARASITES OF BROWN AND SEA-TROUT SALMO-TRUTTA L FROM THE WEST-COAST OF IRELAND

The helminth parasites of 171 trout from three locations in the west o f Ireland were investigated as part of a research programme into recen t declines in sea trout stocks in the area. Of the sample investigated , 135 were sea trout and 36 were brown trout. The sampling sites were located in Drumcliffe Bay, Co. Sligo, Killary Harbour, Co. Galway, and the Burrishoole system, Co. Mayo. The following parasite species were recorded: Discocotyle sagittata, Diphyllobothrium ditremum, Eubothriu m crassum, Acanthocephalus clavula, Acanthocephalus lucii, Echinorhync hus truttae, Pomphorhynchus laevis, Lecithaster gibbosus, Hemiuris spp , Crepidostomum spp, Cystidicola farionis, Hysterothylacium aduncum. T he numbers of helminth species recorded were compared for the differen t trout life-cycle stages. Species richness was found to differ signif icantly between the stages and was highest in the sea trout kelts. Ces tode and acanthocephalan parasites showed particularly marked differen ces in the trout, and the prevalence and intensity of these groups wer e investigated in detail. Worm burden showed significant differences b etween the fish groups.