Conservation and commerce: management of freshwater mussel (Bivalvia : Unionoidea) resources in the United States

The United States is blessed with the world's greatest diversity of freshwa ter mussels (Unionoidea), providing numerous ecological, scientific, and ec onomic benefits to the nation. However, as a result of intense economic dev elopment in the 19th and 20th centuries, this fauna was subjected to habita t destruction, water pollution, and benign neglect that resulted in the los s of populations and species. Presently, about 35 mussel species are presum ed extinct, 69 species are federally protected as endangered or threatened, and numerous other species are candidates for protection. Propagation of t hese endangered species is underway to expedite their recovery. In contrast to this sizable group of rare species, a small assemblage of ubiquitous sp ecies occurring in large rivers and reservoirs within the Mississippi River drainage supports a multi-million dollar commercial shell industry. Most s hells are shipped to the Far East to provide beads for a thriving cultured pearl industry; however, exports in this decade peaked in 1995 and face an uncertain future. Harvest and management regulations are being unified in t he Mississippi River in 1998 to conserve mussel resources from overexploita tion, to resolve law enforcement problems among states, and to consider the exotic zebra mussel, Dreissena polymorpha, which now infests most commerci ally exploited unionid populations. In the next decade, the amount of atten tion given to conservation will decide the fate of this world-class mussel fauna.