Great Basin Naturalist


Following a preliminary survey (1981) of diplostomatosis in fish from the Salmon River near Obsidian, Idaho, an extensive survey was conducted during the summer of 1982. From the initial sampling site on the Salmon River, 98 percent of 384 sculpin, Cottus bairdi, 8 percent of 317 salmonids, and 13 percent of 16 Dace and suckers were infected with Diplostomum spathaceum. Upriver from the initial sampling site and from three drainages entering the Salmon River 28 percent of 185 sculpin and 1 percent of 70 salmonids were infected with D. spathaceum. The number of worms per eye was greater for sculpin (1 to 100+) than for salmonids (1 to 18) from the same area. The metacercariae of D. spathaceum occupy the vitreous body-retina area of infected fish. There is a prominent pathology associated with the infection, including detachment of the retina. Sculpin represent an indicator species for the range of diplostomatosis. The high infection rate of sculpin is associated with their bottom-dwelling characteristic and with their feeding habits.