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Unionid mussels were collected by quadrat sampling at three mussel beds in Reach 15 of the Upper Mississippi River (UMR) between July 1994 and September 1995. A total of 7,107 unionids were collected representing 26 species, including the federally endangered Lampsilis higginsi, state endangered Plethobasus cyphyus and Cumberlandia monodonta, and state threatened Ellipsaria lineolata. Mean densities at our study sites ranged from 53.4 to 118.3 mussels/m2. Comparisons with data collected at these same sites in the early 1980s revealed significant declines in unionid abundance, sporadic recruitment, and extremely slow growth rates. Height-frequency histograms for commercially harvested species remain truncated at...
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During the winter of 1993 1994, we characterized habitats used by 17 radio-tagged largemouth bass Micropterus salmoides in La Grange Reach of the Illinois River, a large river-floodplain ecosystem that has been significantly altered from its natural state. Radio-tagged largemouth bass wintered in backwaters, off-channel coves, ditches, and marinas from November through February. Electrofishing mean catch rates were higher in the study areas during winter than in other seasons, indicating fish were more concentrated in these areas during winter. Five of nine study areas received thermal inputs from springs or power plants, but water temperatures in all nine areas were warmer than the main channel during winter. Current...
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The Long Term Resource Monitoring Program (LTRMP) completed 2,723 collections of fishes from stratified random and permanently fixed sampling locations in six study reaches of the Upper Mississippi River System during 1995. Collection methods included day and night electrofishing, hoop netting, fyke netting (two net sizes), gill netting, seining, and trawling in select aquatic area classes. The six LTRMP study reaches are Pools 4 (excluding Lake Pepin), 8, 13, and 26 of the Upper Mississippi River, an unimpounded reach of the Mississippi River near Cape Girardeau, Missouri, and the La Grange Pool of the Illinois River. A total of 59–72 fish species were detected in each study reach. For each of the six LTRMP study...
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Physical and chemical impacts of human activities have influenced the abundance and diversity of wetland and aquatic plants in the Upper Mississippi River System (UMRS). In 1990, the Long Term Resource Monitoring Program (LTRMP) vegetation component conducted a baseline study that will enable us to document successional changes in the UMRS during the next decade. Five LTRMP stations conducted vegetation studies; this report represents the study at La Grange Pool, Illinois River, during 1990. To obtain a representative sample of the pool, five transects transversing several plant communities were chosen. Transects were chosen according to criteria listed in the LTRMP Procedures Manual, Chapter 6 (Davies 1989). Each...
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The historical importance of mussels to humans is well documented at archeological sites throughout the Illinois River Valley. Native Americans used mussels for food and their shells for tools and ornaments. Early settlers harvested mussels for the infrequent but highly prized pearls they yielded. Beginning about 1891, mussels were used as the raw material for the pearl button industry, which became a multi-million-dollar industry in the United .States by 1899. With the advent of plastics, the pearl button industry died out by the late fifties, but in the sixties, the development of techniques for culturing pearls provided a new market for mussel shells. Today their shells are harvested from Midwestern rivers and...
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