Effectiveness of relative weight (Wr) of bluegill as an indicator of environmental conditions [poster]

Max H. Wolter, Matthew J. Diana, David H. Wahl

Research output: Chapter in Book/Report/Conference proceedingConference contribution


The relative weight (Wr), or “plumpness” of fish, is often considered to be an indicator of environmental conditions. Of these environmental conditions, prey availability is commonly linked to the Wr of piscivorous and specialist species. However, few evaluations have been made regarding the use of Wr for a generalist species as an indicator of environmental conditions. We compared the Wr of several size classes of bluegill in 30 Illinois lakes to an extensive multi-year data set of environmental conditions, including limnological, population, and prey characteristics. Significant positive correlations were found between Wr of bluegill and conspecific biomass and gizzard shad relative abundance. However, we generally found few significant correlations between Wr and a suite of environmental conditions. Although Wr of bluegill may be linked to productivity and prey availability, these relationships may be obscured by a multitude of complex interactions such as density dependent effects, competition and predation risk, parasitism, and other abiotic factors such as turbidity. Our results suggest that Wr is not a strong direct indicator of environmental conditions for a generalist species, especially in ecologically complex systems.
Original languageEnglish (US)
Title of host publicationAmerican Fisheries Society 140th Annual Meeting, September 9-16, 2010, Pittsburgh, PA
StatePublished - 2010


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