Historical Changes in the Distribution of Threatened Channel Darter (Percina copelandi) in Lake Erie with General Observations on the Beach Fish Assemblage

Laurentian Great Lakes beach fish assemblages and the factors influencing their composition have been rarely investigated. In this study, we investigated whether north shore Lake Erie beach fish assemblages, and the distribution of the channel darter (Percina copelandi), a threatened species in Canada, have changed since the late 1940s. Over this time period, Lake Erie has been severely altered by the combined effects of eutrophication, overexploitation of fishery resources, habitat degradation, and invasive species. Seining data from 34 north shore beach sites indicate that a large decline in species richness has occurred, and that several introduced species are present. Three fishes of federal conservation concern and four species of recreational and commercial importance, previously captured from central and eastern Lake Erie basin beaches, were absent. This included the channel darter, which was collected from only one of six historical collection sites, indicating a substantial decline in its Lake Erie distribution. Potential causes of this decline include eutrophication-induced ecosystem changes, the effect of extensive shoreline modification on beaches, and the invasive round goby (Neogobius melanostomus). Nearshore bottom trawls of Long Point Bay indicate that, since the establishment of round goby, concurrent short-term declines in the abundance of two other native benthic fishes (johnny darter Etheostoma nigrum, and logperch P. caprodes) have occurred.