More Lakeshore Houses Can Mean Smaller Fish
People love living on lakes, but they may be damaging the ecosystems they treasure. Compared to lakes with no residential development, lakes with many houses along the shoreline have bluegill sunfish that grow more slowly and are smaller for their age, according to new research presented in the May/June issue of Ecosystems.
This work is the first study of how lakeshore development affects the growth rates of fish in those lakes and was done by Daniel Schindler of the University of Washington in Seattle and co-authors. To determine if lakeshore development affects the growth of fish, Schindler and his colleagues surveyed bluegills (Lepomis macrochirus, a fish common throughout the contiguous U.S.) in 14 lakes in northern Wisconsin and the Upper Peninsula of Michigan. Three of the lakes had no development, seven had low-density residential development, and four had high-density residential development (nearly all of the shoreline was developed).
Residential development in watersheds can increase the nutrient levels in lakes and can decrease the number of dead trees in nearshore waters. Dead trees are critical fish habitat, providing foraging grounds and refuge from predators. The researchers had noted that people remove trees from lakes, presumably to improve both the view of and access to the lake.
Schindler and his colleagues found that as lakeshore residential development increased, bluegill growth rates decreased. The average annual bluegill growth rate in heavily developed lakes was only about 40% of that in undeveloped lakes. The researchers also found that as residential development increased, bluegill populations had increased numbers of older fish, suggesting that the adverse effects of lakeshore development might be greater for young fish than for adults.
These findings suggest that extensive lakeshore development can reduce a lake’s capacity to maintain fish populations. Schindler and his colleagues urge lake and land managers to develop proactive plans that protect a lake’s nearshore and riparian habitats. Schindler’s co-authors are Sean Geib of the University of Wisconsin in Madison and Monica Williams of the University of Maryland-Eastern Shore in Princess Anne.
Schindler, D.E., S.I. Geib, and M.R. Williams. 2000. Patterns of fish growth along a residential development gradient in north temperate lakes. Ecosystems 3:229-237.
Daniel E. Schindler