Habitat Associations of Small Fishes around Islands in the Upper Mississippi River

Abstract

Abstract In large rivers, islands provide a variety of habitat types and increase habitat heterogeneity. Creating or modifying islands with dredged sediments from channel maintenance operations provides an opportunity to enhance habitat features that might promote certain fish communities or general fish abundance. To determine associations between fish species and habitat features of islands, we sampled fish by seining at 62 sites around 20 islands in the upper Mississippi River from Winona, Minnesota, to Prairie du Chien, Wisconsin (180 km). Habitat characteristics were divided into macrohabitat features associated with islands, such as island shape, location, or maximum depth around the island, and mesohabitat features of sites, such as depth, sediment type, and vegetation abundance. Cluster analysis of islands based on macrohabitat features identified four clusters distinguished primarily by water depth and distance from the main channel. Mean fish density did not differ among island clusters. Cluster...