for artificially propagating mussels. Their work led the U.S. Bureau of Fisheries to establish the Fairport Biological Station in Iowa, where further research took place from 1914 into the 1930s.
In that era, before extensive flood control, large numbers of fish were stranded each summer in flooded areas along large rivers. These fish were rescued for return to the rivers, but before they were released, mussel biologists at Fairport Biological Station and elsewhere placed glochidia on them. In the 1920s, 16 fisheries stations throughout the Mississippi River basin released millions of fish, to which were attached billions of glochidia of commercially valuable mussel species.
These efforts were designed to sustain a valuable commercial mussel fishery. Unfortunately, continued overharvest and increasing pollution of the large rivers by municipal and industrial sewage overwhelmed efforts to maintain mussel populations. The numbers of both fish and mussels dwindled, to the point that mussel propagation efforts essentially ended by the early 1930s. At the same time, the great era of dam building began. Over the next 40 years, reservoirs inundated thousands of river miles, further decimating and fragmenting mussel populations.
In 1972, President Richard Nixon signed into law the Clean Water Act. One of its goals was to provide for "the protection and propagation of fish, shellfish, and wildlife."
By the 1980s, improvements in water quality were evident, but so was an increasing realization of what had been lost or was about to be lost. The Endangered Species Act of 1973 reflected public concern for the loss of biological diversity and, through the U.S. Fish and Wildlife Service, gave real support to efforts to prevent extinction.
Mussels were among the first aquatic species to be listed as endangered. In Missouri, naturalist Ronald Oesch wrote Missouri Naiades, a field guide that described the diversity of native mussels in the state. Alan Buchanan, biologist with the Missouri Department of Conservation, surveyed mussels to determine what species might be at risk. Buchanan's reports formed the basis for understanding recent trends in mussel distribution and abundance in Missouri. He documented the last populations of Curtis' pearly mussel, which, despite efforts to protect its remaining habitat, has now disappeared.
In the 1990s, research on Missouri mussels intensified. The Conservation Department used surveys to determine which species were endangered and where the best populations remained. They also identified new threats to the survival of native mussels, including the introduced zebra mussel.