A Comparison of Catch Rates Between the Main Channel and Side Channels in the Middle Mississippi River

The Mississippi River has been drastically influenced through many anthropogenic modifications. Potentially important large-scale habitat features (e.g., side channels and their associated mesohabitats (e.g., substrate, depth, and velocity) have been extensively degraded or reduced (e.g., channelized, leveed, and dammed) in the Mississippi River. The objective of this project was to determine the relative importance of side channel and main channel habitat to the Mississippi River fish community. We examined data collected from 1993 to 2012 by the Long Term Resource Monitoring Program to evaluate catch rates between these two macrohabitat types as well as investigate the influence mesohabitat characteristics have on catch rates. We used standardized catch per unit to evaluate trends across macrohabitats, and in mesohabitat use throughout the Middle Mississippi River. The results of our retrospective analysis did not indicate a general difference in macrohabitat use by the fish community as a whole. However, our results do suggest that fishes more commonly use certain mesohabitats (e.g., low velocities, shallow depths), regardless of substrate type. The use of low velocities and shallow depths in both the main channel and side channels suggests that fishes aren’t seeking out side channel macrohabitat itself, but rather the mesohabitat features it provides.