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Effects of Hydrology on Growth Rate in Freshwater Drum (Aplodinotus grunniens Rafinesque) of the Wabash River

Stephen J. Jacquemin, Jason C. Doll, Mark Pyron, Dustin C. Owen, and Michael Allen, submitted to Fisheries Management and Ecology

Our study objectives were to describe the long term hydrology of the Wabash River USA (1928-2010) and to investigate growth of freshwater drum (Aplodinotus grunniens) in the Wabash River, relative to age, sex, and hydrology. Male and female growth rates were reduced in years with minimum flow events and increased in years with maximum flow events. We compared hydrology variables before and after construction of the major dams in the watershed (1965-1970) using Indicators of Hydrologic Alteration (IHA) software. Minimum flow, the driving variable that was correlated with drum growth, was higher following dam construction. We interpret this as evidence that freshwater drum growth rates were impacted by hydrologic alterations from dam construction. These results provide increased context for the ecology of a large river species in a river with altered hydrology.

Figure 5. 7-day minimum flows at the Montezuma USGS gauging station of the Wabash River for the periods prior to dam construction (pre-1965) and after dam construction (post-1970). Solid lines represent mean flow and dashed lines represent upper and lower 95% confidence intervals.