Graduate Program

Biological Sciences

Degree Name

Master of Science (MS)

Semester of Degree Completion

Spring 2024

Thesis Director

Robert E. Colombo

Thesis Committee Member

Eric K. Bollinger

Thesis Committee Member

Eden L. Effert-Fanta

Abstract

Inland fisheries are experiencing increasing demands due to anthropogenic stressors, especially within large river systems that support both recreational and commercial fisheries. Riverine species are sensitive to habitat degradation, species introductions, and exploitation, so continued monitoring and management of these communities are vital to maintain abundance and diversity within these systems. The North American catfish family, Ictaluridae, supports both recreational and commercial fisheries throughout the United States. Channel Catfish Ictalurus punctatus are heavily studied and managed compared to other sport catfishes in this family because of their economic and ecological significance. One important Channel Catfish fishery exists in the lower Wabash River, which contains the longest free-flowing stretch of river east of the Mississippi. In 2015, regulations were updated to employ congruent harvest regulations in the stretch of river that Illinois and Indiana share. Since then, no study targeting Channel Catfish has occurred. However, Eastern Illinois University (EIU) has monitored the entire fish community, including Channel Catfish, in the Wabash River throughout the past decade through the Long-Term Survey and Assessment of Large River Fishes in Illinois (LTEF) program. Data from this program show a declining trend in the abundance of Channel Catfish in the Wabash. Therefore, the purpose of this study was to assess population parameters of Channel Catfish in the lower Wabash River and provide the Illinois Department of Natural Resources (IDNR) with management recommendations to prevent a further decline in abundance. To do this, I estimated the relative abundance, size structure, condition, age structure, and growth and mortality rates of Channel Catfish in the lower 322 kilometers of the Wabash River using a multiple gear approach. Sampling consisted of alternating-current (AC) and direct-current (DC) boat electrofishing and hoop netting during the spring, summer, and fall of 2022. Results showed low relative abundance and condition in this population, but I observed a larger size and age structure compared to previous studies from 2001-2004 and 2014-2016. A Beverton-Holt yield-per-recruit model suggested current harvest regulations seem sufficient to sustain the population, as the fishing mortality estimate was below the inflection point (Fmax) for the model. Other mechanisms such as annual variation and ecological stressors may contribute to the patterns I observed in this study. I recommend that biologists prioritize a multiple-gear approach when sampling catfish, as hoop nets showed variability in catch, size, and age structure, and future studies should aim to monitor the Wabash River at an ecosystem level to detect broad-scale changes that are likely occurring.

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