Overview

• Researchers found flathead catfish occupy the highest trophic position in invaded reaches, surpassing smallmouth bass and channel catfish.
• Channel catfish shifted to lower trophic levels where flatheads are present, signaling dietary changes likely driven by competition or avoidance.
• All surveyed species exhibited broader, more overlapping diets in invaded sections, consistent with trophic disruption in the river’s food web.
• The team used stable isotope analysis on 279 fish and 64 crayfish, including 79 flatheads, to quantify trophic positions and isotopic niche expansion.
• Findings, published Sept. 4 in Ecology by Penn State, USGS and partners, have managers advising identification and reporting of flatheads, not releasing caught fish, and proper disposal of live bait.