Sport Fish Population Attributes As Influenced By Water Level Fluctuations in Glacial Lakes

A 10 year data set was used to evaluate the influence of water levels on population attributes of yellow perch Perca flavescens and walleye Sander vitreus across a range of glacial lakes in northeastern South Dakota, USA.  Yellow perch abundance was significantly greater during elevated water levels.  Yellow perch size structure, as indexed by the proportional size distribution of quality- and preferred-length fish (PSD and PSD-P), was significantly greater during low water years, as was walleye PSD.  Mean relative weight of walleyes increased significantly during high water periods.  Results showed that natural variation in water levels had an important influence on frequently measured sport fish population characteristics.  While further research is suggested to elucidate mechanisms responsible for differences in sport fish population characteristics owing to dynamic water levels, knowledge of how fish populations respond to water-level fluctuations will ultimately aid in the design and implementation of holistic glacial lake fish management strategies.