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, Cottus cognatus, was examined for Eubothrium salvelini (Cestoda) from May 1995 through September 1996 from Sweetwater Creek, Michigan. No seasonal pattern in prevalence, intensity, and abundance of parasites in trout and sculpin was determined. However a seasonal pattern in the length and percent gravid E. salvelini in brook trout suggests that recruitment of this parasite occurs during late summer and early fall. During this time the procercoid in the copepod intermediate host is expected to be available in the environment for fish to recruit, but a total of 6,399 copepods was not infected. Gravid 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 indicative of seasonal transmission patterns than studies that only measure prevalence, abundance, and intensity.