Water Quality as a Detterent to the Movement of Invasive Fishes in the Illinois Waterway: Implications for the Upper Mississippi Basin

Since their escape decades ago, invasive silver and bighead carp have been spreading throughout the Mississippi Basin and are currently the most abundant fish in some parts of the Illinois River. Interestingly, bighead carp have not moved further upstream in the Illinois River for more than a decade, with the leading edge “stalled” just south of Joliet, Illinois. Understanding the mechanism responsible for why invasive carp have not moved farther upstream can provide information on factors controlling their spread and can help identify when they might start moving in the future. The current project tests the hypothesis that the upstream movement of invasive bighead carps has been deterred because of the presence of anthropogenic pollutants in the Chicago Area Waterway System (CAWS). To test this hypothesis, three experiments were performed. First, water from the CAWS was transported to the Upper Midwest Science Center and hatchery-reared silver carp were exposed to this water. Results showed that silver carp in CAWS water displayed reduced activity and increased energy expenditure, providing a putative mechanism explaining the lack of upstream movement. The second study exposed carp from the southern portion of the Illinois River to CAWS water, and the activity of genes related to stress and disturbance was quantified; those data are currently being analyzed. The final study quantified the stress, disturbance, and physical condition of carp along the length of the Illinois River, including the “leading edge,” to quantify stress in free-swimming fish. Together, the results can help explain the lack of upstream movement of carp.

  • PI: Cory Suski
  • PI Institution: University of Illinois
  • March 24, 2021 – March 23, 2024