Adult and larval fish assemblages vary among small tributary mouths of Green Bay, Lake Michigan

Abstract

Small tributaries of the Great Lakes serve as important habitat during critical life stages of many fish species, though temporal and spatial dynamics of the assemblage that uses these systems are seldom investigated. This study quantifies larval and adult fish assemblages captured by fyke net and light traps among small tributary mouths of Green Bay, Lake Michigan. Ten tributaries harbored a total of 45 species representing 17 families, with the most abundant including spottail shiner (Notropis hudsonius (Clinton, 1824)) in adult assemblages and white sucker (Catostomus commersonii (Lacepède, 1803)) in larval assemblages. Larval fish assemblage structures differed over five biweekly sampling events in May and June. Adult fish assemblage structures varied among tributaries but not among spring, summer, and fall samples. Larval and adult species assemblages at these river mouths are likely influenced by hydrology, habitat structure, and species-specific ecology. Water movement may transport larvae into river mouths, as larval assemblages were dominated by species that spawn in coastal habitats. Adult species richness varied with longitude, with the greatest diversity in tributaries on the west shore. This investigation of fish assemblages highlights the spatial and temporal variation that occurs in these systems and their role in shaping fish populations in Green Bay.