Infestation of Salmincola californiensis (Copepoda: Lernaeopodidae) in wild Coho Salmon, steelhead, and coastal cutthroat trout juveniles in a small Columbia river tributary

Host-parasite relationships between Salmincola californiensis (order Copepoda, family Lernaeopodidae) and three species of wild juvenile Pacific salmonids (coho salmon Oncorhynchus kisutch, cutthroat trout O. clarki, and steelhead O. mykiss) were studied in Gibbons Creek, southwestern Washington, during 1998 and 1999. Infestation levels were moderate to low: prevalence was 0.2% in coho salmon, 20% in cutthroat trout. and 35% in steelhead; abundance was 0.01 in coho salmon, 0.63 in cutthroat trout, and 0.97 in steelhead; and mean intensity was 3.4 for cutthroat trout and 2.95 for steelhead. The incidence of infestation increased with increasing fish length, and this relationship may explain the differences in prevalence experienced by the three host species.