Determining Recruitment Sources and Movement Patterns of Sauger Sander Canadensis in the Kaskaskia River, Illinois Using Otolith Microchemistry

Sauger populations have been negatively impacted by habitat alteration and dam construction and have experienced declines across much of their range due in part to these modifications. Knowledge of recruitment sources and movement patterns is essential to maintain a sustainable Sauger population because of the migratory nature of the species. The Kaskaskia River, Illinois supports an important recreational Sauger fishery; however, little is known concerning the influence of hatchery and wild stocks on the Sauger population, as well as the timing and frequency of migration patterns in light of two large dams that exist on the river (including one near the Kaskaskia-Mississippi River confluence). To evaluate these influences, Sauger were collected in fall 2015 and spring 2016 via boat electrofishing. We then used otolith microchemistry to analyze a suite of trace elements and stable oxygen isotopic composition (δ¹⁸O) to determine natal origin and environmental history of Sauger collected from the Kaskaskia River. Results of this study will provide fishery managers with information regarding the contributions of stocked and wild fish to the Sauger population and the extent of fish movement between the Kaskaskia and Mississippi rivers.