Analysis of fish age structure and growth in the Illinois River

Smith, M. A., M. A. Pegg, and K. S. Irons. 2007. Analysis of fish age structure
and growth in the Illinois River. U.S. Geological Survey, Upper Midwest
Environmental Sciences Center, La Crosse, Wisconsin, June 2007. LTRMP
Technical Report 2007–T002. 55 pp.

Abstract: Otoliths and other calcified structures have been used to age and
determine growth rates of fish from a variety of habitats. Sagittal otoliths were
removed from fishes representing five species from La Grange Pool of the Illinois
River for age determination. Species collected included largemouth bass
(Micropterus salmoides), black crappie (Pomoxis nigromaculatus), bluegill
(Lepomis macrochirus), white bass (Morone chrysops), and freshwater drum
(Aplodinotus grunniens). Common univariate techniques were used to analyze the
significance of spatial and temporal variation in growth and back-calculated mean
length-at-age for all five species. 

Keywords: Age structure, growth, Illinois River, La Grange Pool, otolith