Document Type



smallmouth bass, population characteristics, Iowa rivers


Smallmouth bass Micropterus dolomieu are a popular sport fish throughout North America and occupy an important ecological role as top predators in aquatic systems. Despite the importance of smallmouth bass, knowledge of their population structure and dynamics in Iowa interior rivers is limited. The objective of this study was to describe population dynamics (e.g., relative abundance, size and age structure, growth, mortality) of smallmouth bass in six Iowa rivers. Smallmouth bass were sampled from the Upper Iowa, Maquoketa, and Wapsipinicon rivers in northeast Iowa and the Des Moines, Iowa, and South Skunk rivers in central Iowa using electrofishing during the fall of 2005. Scales were removed for age and growth estimation. Dorsal spines were removed from fish greater than 350 mm for comparison with scales. Relative abundance, size structure, condition, age structure, growth, and mortality varied among populations. For instance, proportional size distribution varied from 26 to 73 relative weight (Wr) varied from 83 to 102, and total annual mortality of age-2 and older fish varied from 23 to 62% among populations. Smallmouth bass in the Maquoketa and South Skunk rivers generally had the fastest growth rates, while smallmouth bass in the Iowa and Wapsipinicon rivers exhibited the slowest growth. This study provides information that contributes to our knowledge of smallmouth bass ecology, and will be useful for guiding management decisions and making regional and national comparisons.

Publication Date

January-December 2008

Journal Title

Journal of the Iowa Academy of Science





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© Copyright 2009 by the Iowa Academy of Science, Inc.



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