Many people think the Lower Mississippi River is simply a highway for barges. While it does provide an incredibly efficient transportation artery for commodities, it is much more than a navigation channel. Although the historic floodplain of the lower river is now confined by a levee system, the land that lies between those levees in not entirely used for navigation. There are numerous side channels, old river chutes, oxbow lakes, and millions of acres of forested and cleared lands that support a large diversity of fish and wildlife, including around 100 fish species, trophy white-tailed deer, and a corridor for 40% of migratory waterfowl in the United States.
Side channels provide crucial slack water habitat for many fishes as well as feeding areas for birds and other wildlife. However, many side channels are closed off to water flow due to the construction of closing dikes. Rock dikes decrease dredging costs by focusing water flow to allow self-scour of the navigation channel.
Since 2006, the Lower Mississippi River Conservation Committee has worked with the U.S. Army Corps of Engineers and the U.S. Fish and Wildlife Service to remove sections of the dikes to allow water flow into side channels, providing more habitat for fish to spawn, feed and rear their young. Side channels and other important river habitats, such as natural banks, sloughs, oxbow lakes and others, are among 13 aquatic habitats delineated in a 1991 technical paper by researchers at the U.S. Army Engineer Research and Development Center.
The paper, for example, describes the differences between natural steep banks and revetted banks, those with materials, such as concrete, placed over them to prevent erosion. Different types of aquatic insects and other invertebrates colonize the two types of banks, thus presenting different food resources for fish. Oxbow lakes were formed from an abandoned river channel and usually do not have river current flowing through them except during high river stages. However, many fish species use floodplain lakes for spawning and rearing habitat.
Fishing the Lower Mississippi River, a guide produced by the LMRCC, also contains descriptions of varied river habitats, with particular attention to the types of fish that may be caught in these areas.
With river stages varying as much as 50 feet during the year, aquatic habitats are always changing.