HELMINTHS AND FOOD-HABITS OF LAKE STURGEON ACIPENSER-FULVESCENS FROM THE LAKE WINNEBAGO SYSTEM, WISCONSIN

Eight species of helminths were recovered from 45 summer (June-August) and 29 winter (February) lake sturgeon adults and juveniles, from Lak e Winnebago, Wisconsin. Eighteen young-of-the-year (YOY) sturgeon coll ected from the wolf River were uninfected. Both summer and winter helm inth communities were dominated by host specific parasites such as Cre idostomum auriculatum, Skrjabinopsolus manteri, Capillospirura pseudoa rgumentosa and Truttaedacnitis clitellarius. Examination of stomach co ntents indicated the chironomids were the most important food items an d comparison with past records on lake sturgeon diet suggests and unch anged use of the benthos of Lake Winnebago. The eutrophic nature of La ke Winnebago is probably responsible for the absence of Hexagenia spp, an important component of the diet of lake sturgeon from other system s, which would explain the absence of a host specific nematode, Spinit ectus acipenseri. Although the trophic status of the lake may modify t he helminth community, some host specific endo-helminths (C-ariculatum , C-pseudoargumentosa) appear to be transmitted in riverine environmen ts (deeper downstream channels) used as feeding areas by older (2 yr+) sturgeon. Differences in habitat and diet of YOY sturgeon in the Wolf River and the absence of any host specific helminths in these juvenil es also indicate that the community of host specific helminths is not recruited until YOY juveniles enter deeper downstream channels to feed .