Fish Assemblages from Chevron Dikes in the Middle Mississippi River

Chevron dikes are a relatively new structure designed by the U.S. Army Corps. of Engineers to aide navigation by concentrating flow and inducing channel scour.  They have also been justified for promoting physical habitat and habitat heterogeneity.  To date, only a few studies of fish community have occurred for these structures.  Since 1993, river miles 29-80 on the Middle Mississippi have been monitored for fish community structure and water quality for the Long Term Resource Monitoring  (LTRM) element of the Upper Mississippi River Restoration Program.  With this program, several habitats are sampled which include artificially manipulated river structures.  However, chevrons are not included in the sampling protocol because chevrons were constructed well after the program sampling methods were established.  Also, the Open Rivers and Pool 26 are the only two of six LTRM reaches that have chevrons.  The Open Rivers reach has seven chevron dikes.  Until this study, only sporadic trotlining, electrofishing, and trawling from the Missouri Department of Conservation and the U.S. Army Corps. of Engineers have been done to evaluate these chevrons.  The objective of this study is to compare fish community assemblages between traditional wing dike structures and chevron dikes using LTRM electrofishing and hoop netting.