Growth Chronology of Channel Catfish and Freshwater Drum across Six Illinois Rivers

Channel catfish (Ictalurus punctatus) and Freshwater drum (Aplodinotus grunniens) are two prominent North American sportfishes occupying a similar ecological niche in many river systems. Comparison of historically validated ageing structures and length frequency data can reveal dynamics of riverine fish populations, including their recruitment, mortality, and individual growth patterns. In addition, tracking years of strong and weak growth through biochronological inference can increase understanding of the biotic and abiotic factors affecting individual reaches and rivers. This collaborative project covers reaches of six major rivers spanning Illinois, including the Wabash, Ohio, Illinois, Kankakee, Iroquois, Pools 16, 19, 20, 21, and 25 of the upper Mississippi River, as well as a small section of the lower Mississippi River. Results from 2017 revealed weak year classes in all reaches for drum from 2010 to 2014. Catfish showed weak years before 2011 and after 2014. Otolith increment width accounting for individual fish and year, using mixed effect modeling, indicate high variability in growth between these populations among years as reflected by variability in discharge and water temperature. Understanding population dynamics and growth chronology of two common predatory fish spanning Illinois’ waterways is essential for creating potential management strategies.