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 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. All fish were caught in 2017 and 2018 using DC electrofishing gear as part of a long term survey submitted annually to the Illinois Department of Natural Resources. Preliminary results from 2017 revealed weak year classes in all reaches for drum from 2010 to 2014, but stronger classes in the following years. Catfish showed weak years before 2011 and after 2014, but stronger years in between. Drum had faster growth rates in the Ohio and Mississippi reaches and slower growth in the Illinois and Wabash, whereas the catfish initially had faster growth rates only in the Ohio River. Mortality rates were highest for drum in the upper Mississippi River in pools 16 & 19, but lowest in the Ohio River. Catfish mortality rates were low throughout all reaches. Incorporating chronology factors as well as the data collected in 2018 may reveal additional trends and the larger dataset will allow us to further compare pools and reaches within each river. Understanding population dynamics and growth chronology of two common predatory fish spanning Illinois waterways is important for creating potential management strategies and determining their initial necessity.
|Title of host publication
|Midwest Fish and Wildlife Conference 2019
|Published - 2019