Comparative Ecology Of Three Minnow Species In East-Central Illinois
Clinton R. Kowalik, Assistant Fisheries Biologist, Fish Management District 8, Vallonia, IN 47281; (812) 358-4110; FAX (812) 358-3087; ckowalik@dnr.IN.gov
Age-groups, growth rates, and spawning periods are reported for sympatric populations of silverjaw minnow (Ericymba buccata), bigmouth shiner (Notropis dorsalis), and sand shiner (Notropis ludibundus) in Champaign County, Illinois. East-central Illinois is one of the few places in North America where the three species coexist. At least one site from the Kaskakia Ditch, Embarras River, and Wildcat Slough were collected once a month from January to December 2002. All three species were collected together from Kaskaskia several times during the sampling period, including young-of-the-year. Spawning was not observed in the field or in aquaria. Over the sampling period, N. ludibundus outnumbered the other two species at Kaskaskia, E. buccata outnumbered N. ludibundus at Embarras, and N. ludibundus greatly outnumbered N. dorsalis at Wildcat. Only four E. buccata were collected at Wildcat during this study. Embarras E. buccata were more abundant, larger, and in better condition than Kaskaskia E. buccata. Wildcat N. dorsalis were more abundant than, smaller than, and in similar condition with Kaskaskia N. dorsalis. In general, N. ludibundus is relatively abundant and in better condition (especially Kaskaskia adults) than the other two species at all sites. Hybridization between E. buccata and N. dorsalis has not been previously reported in literature; however, twenty-seven specimens collected from the upper Kaskaskia River basin in 2002 were identified as silverjaw-bigmouth hybrids (Ericymba buccata x Notropis dorsalis). These individuals possess physical characteristics intermediate between the two aforementioned species: intermediate-arched body, intermediate-sized mouth, and "pearl organs" reduced in size and appearance.