Parasites of farm-raised trout in Michigan, USA

A total of 635 trout (366 rainbow trout, Oncorhynchus mykiss Richardson, 18 36; 156 brook trout, Salvclinus fontinalis Mitchill, 1814; 103 brown trout, Salmo trutta Linnaeus, 1758; Salmonidae) collected in March-July 1996, 199 7, and 1998 from 12 trout farms in Michigan, U.S.A., was examined for paras ites. Twelve parasite species (1 Acanthocephala, Acanthocephalus dirus (Van Cleave, 1931) Van Cleave and Townsend, 1936; 1 Monogcnea, Gyrodactylus sp: 2 Cestoda, Eubotrium salvelini (Schrank, 1790), Proteocephalus sp.: 1 Nema toda, Truttaedacnitis sp.: 1 Copepoda, Salmincola edwardsii (Olsson, 1869); 1 Myxozoa, Myxobolus cerebralis (Hofer, 1903); 4 Ciliophora, Capriniana sp . [=Trichophyra sp.], Chilodonella sp., Ichthyophthirus multifiliis (Fouque t, 1876), Trichodina sp.; and 1 Mastigophora, Ichthyobodo sp. [=Costia sp.1 ]) were found. Rainbow trout were infected with A. dirus, Truttaedscnitis s p., E. salvelini, Proteocephalus sp, Gyrodactylus sp., M. cerebralis, Ichth yobodo sp., Capriniana sp., Chilononella sp., I. multifiliis, and Trichodin a sp. Brook trout were infected with A. dirus, S, edwardsii, E. salvelini, M. cerebralis, and Trichodina sp. Acanthocephalus dirus was the only parasi te infecting brown trout. Eubothrium salvelini, A. dirus, and Trichodina sp . infected trout from 9. 8. and 8 farms, respectively. Acanthocephalus diru s in all trout species and S. edwardsii on brook trout had the highest prev alences, mean intensities, and mean abundances.