Seasonal patterns in the biology of Eubothrium salvelini infecting brook trout in a creek in lower Michigan

A total of 392 brook trout, Salvelinus fontinalis, and 211 slimy sculpin, C ottus cognatus, was examined for Eubothrium salvelini (Cestoda) from May 19 95 through September 1996 from Sweetwater Creek, Michigan. No seasonal patt ern in prevalence, intensity, and abundance of parasites in trout and sculp in was determined. However a seasonal pattern in the length and percent gra vid E. salvelini in brook trout suggests that recruitment of this parasite occurs during late summer and early fall. During this time the procercoid i n the copepod intermediate host is expected to be available in the environm ent for fish to recruit, but a total of 6,399 copepods was not infected. Gr avid worms were not found in slimy sculpin, suggesting it is a paratenic or dead-end host. Detailed studies on the biology of parasites may be more in dicative of seasonal transmission patterns than studies that only measure p revalence, abundance, and intensity.