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Article by Calvin R. Fremling, Jerry L. Rasmussen, Richard E. Sparks, Stephen P. Cobb, C. Fred Bryan, and Thomas O. Claflin regarding human industry and impact on the fish populations of the Mississippi River, interactions between upper and lower river valleys, fish types, commercial fish harvests, water quality, and fishery projections. Abstract: "The Mississippi River (MR) is severely regulated, mainly for transportation and flood control. The Headwaters (HW) flow through 9 eutrophic and mesotrophic glacial lakes and 11 dams. Intensive channelization of the Upper Mississippi River (UMR) for navigation was begun in 1878, and the river is now routinely dredged. Broad, shallow impoundments were created on the UMR when 29 navigation dams were constructed during the 1930s to create a slack-water navigation channel 2.7 —m deep between St. Louis, Missouri, and St. Paul, Minnesota. The Lower Mississippi River (LMR) has been channelized and shortened 229 km, but remains undammed; its natural floodplain has been decreased about 90% by levee construction begun in 1727. The Atchafalaya River (AR), a major distributary and distinct ecological component, normally receives about 20% of the discharge of the mainstem MR. MR backwaters are important fish production and nursery habitats, and most may be lost to sedimentation and eutrophication within 50 yr. Louisiana's coastal wetlands are critical to marine fishes and invertebrates, and about 0.6% are being lost yearly to natural and human-induced forces, including levees which divert sediment directly into the Gulf of Mexico, instead of allowing it to build up the delta during annual floods. Although the supply of organic matter (OM) carried downstream in the main channel exceeds requirements for secondary production within the river, the bulk of this OM may be recalcitrant and of little nutritional value to invertebrates and fish. Distribution of 241 fish species reported from mainstem MR and AR has been influenced mainly by glaciation, natural barriers and human activities; species diversity generally increases downstream. Estimated annual UMR commercial fish harvest has ranged from 22.9 kg*ha-1 to 32.8 kg*ha-1 with standing stock estimates ranging as high as 1.035 kg*ha-1. in a tributary mouth of the Middle Mississippi River (MMR). Average standing stock in backwaters within the unleveed AR basin is 860 kg*ha-1. Annual harvest of sport fish on the UMR ranges from 15.9 kg*ha-1 in northern pools to 2.9 kg*ha-1 in southern pools. Throughout the MR and AR, sport fishing contributes much more to the economy than commercial fishing. A positive relation exists between area of inundated AR floodplain and commercial harvest of aquatic animals whose life spans approximate one year. There are fewer fishing regulations on the LMR and AR than on the HW, UMR, or MMR but they are considered adequate because the fishery apparently accommodates local demands. Recent environmental legislation requires mitigation for loss of fish and wildlife habitat, as well as rehabilitation of areas already degraded." Article reprinted as a distinct publication from Canadian Special Publication of Fisheries and Aquatic Sciences 106, Proceedings of the International Large River Symposium. Edited by Douglas P. Dodge. Produced by Fisheries and Oceans, Canada. Part of the Cal R. Fremling Collection.
Biologists; Pollution; Upper Mississippi River; Fish Fisheries
Fremling, Cal R., "Mississippi River Fisheries: A Case History" (1989). Cal Fremling Papers. 34.
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