Wednesday, August 6, 2008 - 9:00 AM

COS 47-4: Coarse woody habitat density and largemouth bass (Micropterus salmoides) growth rates

Jereme W. Gaeta1, Matthew J. Guarascio1, Greg G. Sass2, and Stephen R. Carpenter1. (1) University of Wisconsin Madison, (2) University of Illinois

Background/Question/Methods

Residential development along lakeshores is correlated with a decrease in the amount of coarse woody habitat (CWH) available for fishes in the littoral zones of lakes in Wisconsin’s Northern Highland Lake District. Previous work has associated the decline in CWH with decreasing growth rates of bluegill and suggested a similar trend for largemouth bass, but causes of the fish response remain uncertain. To expand the scope of the analysis and identify the mechanism influencing growth, we sampled 60 lakes across gradients of housing density and landscape position, measuring characteristics of the lakeshore, littoral zone, water chemistry, and fish communities. In 16 of these lakes, across a gradient of housing density, we measured age-specific and size-specific growth rates of largemouth bass (30 fish per lake).

Results/Conclusions

Size-specific and age-specific growth rates confirmed the decrease of largemouth bass growth as CWH declines and housing density increases. In addition, size-specific growth rates of bass between 77 mm and 225 mm were directly correlated with conductivity, a surrogate for landscape position. These findings corroborate previous studies showing adverse effects of lakeshore residential development on amphibian, bird and fish communities. It adds to that work by demonstrating statistically significant declines in growth of an important sport fish, largemouth bass. Our findings also suggest that landscape position interacts with the effect of lakeshore housing on largemouth bass growth. Thus, it may be important to consider effects of landscape position when evaluating the impacts of lakeshore development on aquatic resources.