Black bass are the most popular and most economically important freshwater game fish in the United States, especially in the southeastern part of the country. In a 1996 national recreational survey, 52 percent of anglers in the southeastern United States fished for black bass. Each year, anglers spend billions of dollars in pursuit of black bass. As a result of the popularity and economic importance of black bass, there is widespread interest in maintaining healthy populations.

This particular study shows that black bass populations in streams in the Lower Mississippi River floodplain (locally known as the Delta) reflect differences in stream water quality. This suggests that black bass populations could be expected to improve in some streams if water-quality conditions were to improve.

In the Delta, physical characteristics of the natural streams, combined with human activities and practices, have resulted in a unique set of ecological conditions. For example, compared to upland streams, Delta streams naturally have lower velocities, higher turbidity, and less stable concen- trations of dissolved oxygen.

Furthermore, clearing of bottomland hardwoods from much of the land in the Delta, including the stream banks, has resulted in a loss of tree canopy, which has affected Delta streams in at least three important ways.

There has been 1) a reduction of fallen limbs and trees in the streams, which is a preferred habitat of many fish species; 2) an increase in water temperatures because there is less shade; and 3) a reduction in the amount of organic matter (for example, leaves), which is an important food source for organisms at the bottom of the food chain in the aquatic environment.

Lastly, most streams in the Delta have been channelized to facilitate drainage and to control flooding. As a result of human activities such as stream-channel dredging, the natural in-stream habitats of most Delta streams have been altered.