AUTHORS: Ethan T. Scott, Eastern Illinois University; Daniel R. Roth, Eastern Illinois University; Eden L. Effert-Fanta, Eastern Illinois University; and Robert E. Colombo, Eastern Illinois University
ABSTRACT: This study investigates the population dynamics of Smallmouth Bass (Micropterus dolomieu) in the Kaskaskia and Vermilion Rivers in Illinois, comparing supplementally stocked populations with naturally reproduced ones. Stocking efforts in the Kaskaskia River have aimed to support recreational fisheries for over a decade. Yet, the contribution of stocked fish to long-term population sustainability has not been fully assessed. In contrast, the Vermilion River supports natural recruitment, and recent dam removals have improved fish diversity and habitat quality, potentially benefiting the abundance of sportfish like Smallmouth Bass. Our primary objectives are to evaluate the relative abundance and demographics of Smallmouth Bass populations in both rivers and assess dynamic rate functions such as age, growth, and mortality. To achieve these objectives, we conducted surveys at 12 sites in each river using pulsed-DC boat electrofishing during the spring and fall. All fish were measured, weighed, and tagged with passive integrated transponder (PIT) tags. Pectoral fin rays were collected as a non-lethal aging structure, and microchemistry analysis will be used to identify recruitment sources by examining elemental ratios. Initial results from the Kaskaskia River suggest that this population is primarily supported by stocking, with Smallmouth Bass most abundant in areas where stocking occurs, particularly near the Shelbyville Dam. This study will provide critical insights into the effectiveness of supplemental stocking in enhancing Smallmouth Bass populations while identifying the natural factors that contribute to successful recruitment in free-flowing systems like the Vermilion River. By comparing two rivers with distinct recruitment mechanisms and environmental stressors, this research will inform more effective management strategies tailored to each system. The findings will also offer broader applications for managing Smallmouth Bass fisheries across similar Midwestern River systems.
