0 Inchausty, Victor H. Michael Foutz Richard A. Heckmann Claudete Ruas Paulo Ruas 1997 Great Basin Naturalist 57 178-183 April, 1997 cutthroat trout, diplostomiasis, fish, introduced species, lake trout, native species, parasite, Trematoda strigeidae, wildlife health, Yellowstone trout, Diplostomum spathaceum Totals of 101 native Yellowstone cutthroat (Oncorhynchus clarki bouvieri), 27 introduced lake trout (Salvelinus namaycush), and 40 introduced longnose sucker (Catostomus catostomus) from Yellowstone Lake, Wyoming, USA, were examined for eye flukes. Metacercariae of the trematode fluke Diplostomum were in vitreous humor and/or lens of 94% of Yellowstone cutthroat trout, 92% of lake trout, and 78% of longnose sucker. Longnose sucker had 7% prevalence of infection in both lens and vitreous humor of metacercariae, while Yellowstone cutthroat trout had 3% and lake trout 8%. Diplostomum spathaceum was in lens tissue of 5% of infected Yellowstone cutthroat trout and lake trout. Morphological characteristics indicate that a single species infected the lens of the Yellowstone cutthroat trout and longnose sucker, while another species infected lake trout. Impacts of the parasite interchange between native and introduced fishes of Yellowstone Lake, Wyoming, are unknown but should be monitored each year. Found at Yellowstone Research LibraryNatureBib ID: 628891