Date of Graduation

Summer 2020


Master of Science in Biology



Committee Chair

Quinton Phelps


Fish populations are driven by the dynamic rate functions (i.e., recruitment, growth, and mortality). Knowledge of these vital rates can provide critical information to determine spatiotemporal population-level changes in the system. Therefore, understanding these vital rates are important in the proper management of any fishery. Anthropogenic modifications to the environment have had damaging effects on the organisms within these ecosystems. Specific to Upper Mississippi River fishes, channelization, dams, and loss of floodplain connectivity have all been purported as deleterious. In the face of these modifications, understanding habitat use and vital rates of individual species is needed to help guide management and restoration efforts. Furthermore, Bluegill Lepomis macrochirus are an important indicator species that may provide insight on the broader fish community (e.g., “canary in a coal mine”). As such, the objective of this study is to determine the habitat use and population demographics of Bluegill in the Upper Mississippi River system. Knowledge of vital rates and habitat needs will provide a baseline for managers as a reference to future changes in the river. Bluegill were collected via electrofishing conducted by the United States Army Corps of Engineers’ Long-Term Resource Monitoring (LTRM) element. Habitat data was collected during electrofishing events conducted at three field sites (Pool 4 in Lake City, MN, Pool 8 in Onalaska, WI, and Pool 13 in Bellevue, IA) in the Upper Mississippi River from 1993-2017. Fish used for vital rate analysis were collected at five field sites via electrofishing (Pool 4 in Lake City, MN, Pool 8 in Onalaska, WI, Pool 13 in Bellevue, IA, Pool 26 in Alton, IL, and the Open River reach in Cape Girardeau, MO) in the Upper Mississippi River during the summer of 2018. The information garnered in this study can be used to help direct management efforts that not only favor Bluegill, but also other fishes in the Upper Mississippi River.


Bluegill, habitat, population dynamics, vital rates, electrofishing, Mississippi River, backwater

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© Ethan Allyn Rutledge

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