NEMATODES OF YELLOW PERCH FROM SAGINAW BAY, LAKE-HURON, WITH EMPHASISON EUSTRONGYLIDES-TUBIFEX (DIOCTOPHYMATIDAE) AND PHILOMETRA-CYLINDRACEA (PHILOMETRIDAE)

Two hundred forty yellow perch, Perca flavescens (Mitchill), collected from 4 locations in Saginaw Bay, Lake Huron, Michigan, in May and Sep tember/October 1992, were examined for nematodes. A total of 6 nematod es species (Eustrongylides tubifex (Nitzsch, 1819) Jagerskiold, 1909; Philometra cylindracea (Ward and Magath, 1917) Van Cleave and Mueller, 1934; Dichelyne cotylophora (Ward and Magath, 1917) Fetter, 1974; Rap hidascaris sp. Railliet and Henry, 1915; Camallanus oxycephalus Ward a nd Magath, 1917; and an unidentified gravid female nematode) infected yellow perch; E. tubifex and P. cylindracea were most common. Prevalen ces and mean intensities varied with month and location of yellow perc h collection. Yellow perch from The Black Hole, which is the most eutr ophic location, had a significantly higher mean intensity of E. tubife x than fish from other locations. Prevalence and intensity of E. tubif ex increased in larger and older yellow perch. The mean intensity of P . cylindracea did not vary significantly with location. Occurrence of E. tubifex and P. cylindracea is influenced by the distribution of int ermediate and/or paratenic hosts, the feeding habits of the perch, and the life histories of the nematodes.