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Relationship of weed shiner and young-of-year bluegill and largemouth bass abundance to submersed aquatic vegetation in Navigation Pools 4, 8, and 13 of the Upper Mississippi River, 1998– 2012

DeLain, S.A., and Popp, W.A., 2014, Relationship of weed shiner and young-of-year bluegill and largemouth bass abundance to submersed aquatic vegetation in Navigation Pools 4, 8, and 13 of the Upper Mississippi River, 1998– 2012: A technical report submitted to the U.S. Army Corps of Engineers’ Upper Mississippi River Restoration-Environmental Management Program from the U.S. Geological Survey, Technical Report 2014–T001, 29 p.

Abstract

Aquatic vegetation provides food resources and shelter for many species of fish. This study found a significant rela­tionship between increases in submersed aquatic vegetation (SAV) in four study reaches of the Upper Mississippi River (UMR) and increases in catch-per-unit-effort (CPUE) of weed shiners (Notropis texanus) and age-0 bluegills (Lepomis mac­rochirus) and largemouth bass (Micropterus salmoides) when all of the study reaches were treated collectively using Long Term Resource Monitoring Program (LTRMP) vegetation and fish data for 1998–2012. The selected fishes were more abun­dant in study reaches with higher SAV frequencies (Pool 8 and Lower Pool 4) and less abundant in reaches with lower SAV frequencies (Pool 13 and Upper Pool 4). When each study reach was examined independently, the relationship between SAV frequency and CPUE of the three species was not significant in most cases, the primary exception being weed shiners in Lower Pool 4. Results of this study indicate that the prevalence of SAV does affect relative abundance of these vegetation-associated fish species. However, the poor annual relationship between SAV frequency and age-0 relative abun­dance in individual study reaches indicates that several other factors also govern age-0 abundance. The data indicate that there may be a SAV frequency threshold in backwaters above which there is not a strong relationship with abundance of these fish species. This is indicated by the high annual CPUE variability of the three selected fishes in backwaters of Pool 8 and Lower Pool 4 when SAV exceeded certain frequencies.

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