Mississippi Lakes Revitalized As Fisheries
By Hank Becker
March 22, 2001
Fishermen can now cast their lines
into two Mississippi freshwater lakes that have been revitalized as sports
Natural lakes in the Mississippi Delta, long known for their productivity
and recreational value, have declined because of poor water quality. Sediment
from agricultural runoff interferes with plankton growth, the foundation of all
life in freshwater lakes.
Now, best management practices (BMPs) have been designed to reduce
sediment-laden runoff from agricultural lands and improve water clarity. ARS
ecologist Scott Knight at the
Sedimentation Laboratory, Oxford, Miss., conducted a study to evaluate the
restocking of sports fish in three lakes with watersheds that have been
improved by implementing BMPs.
The lakes under study are called oxbow lakes, created when a river cuts a
new path across a large bend--usually during flooding--and isolates a u-shaped
section of the river. Oxbows make perfect ecology laboratories because they are
essentially closed ecosystems.
Sports fish were successfully reintroduced in the two lakes whose watersheds
were protected with culture-based BMPs like conservation tillage and cover
crops. Structural BMPs used to reduce water flow speeds and filter sediment
included grade stabilization structures, like slotted inlet pipes; tall fescue
grass filter strips, and riparian forest buffer zones. The third lake was
protected by only structural measures which did not reduce sediment enough to
ecologically improve it.
The two lakes protected by culture-based BMPs had the most significant
improvement in water quality. Increasing water clarity boosts plankton growth,
a necessity for a good sports fishery. Bass populations, lacking before
renovation and restocking, were successfully established in these two lakes.
The scientists say their results indicate that cultural BMPs may play a more
significant role in improving lake water quality and may be needed in addition
to structural measures to ensure improvement of fisheries in oxbow lakes. ARS
is the U.S. Department of Agricultures
chief scientific research agency.
Scientific contact: Scott Knight, ARS National Sedimentation
Laboratory, Oxford, Miss., phone (662) 232-2935, fax (661) 232-2934,