Bringing Mussels Back in the Southeast - Brief Article

Endangered Species Bulletin, May, 2000 by Richard G. Biggins, Robert S. Butler

The world's greatest diversity of freshwater mussels occurs in the continental United States. Early American naturalists marveled at this fauna's beauty and diversity. T.A. Conrad wrote in a paper presented to the Academy of Natural Sciences of Philadelphia in 1834, "The great variety and beauty of the flesh water shells of this country are truly surprising. Whilst the streams of Europe contain very few species, not remarkable for elegance of color or variety, the rivers of Ohio, Kentucky, Tennessee, Alabama, etc., contain at least one hundred species of almost every imaginable shape."

Native Americans made extensive use of this abundant natural resource. Mussels in unimaginable numbers once paved the shallow shoals of many rivers and provided an easily accessible food supply. Many of the shells were fashioned into spoons, plates, hoes, and an array of other tools, and some of the colorful and ornate shells were transformed into adornments. In spite of extensive use, this mussel fauna remained relatively unchanged for centuries prior to European settlement.

However, during the last 100 years, the habitat of this rich fauna (nearly 300 species) has been inundated by impoundments, smothered in silt, dredged for navigation, and polluted with toxins. The U.S. Fish and Wildlife Service currently recognizes about 12 percent of our mussel fauna as extinct and 23 percent as threatened or endangered. No other widespread North American animal group has experienced this level of collapse. For example, The Nature Conservancy (TNC) considers 68 percent of our nation's mussel species at risk, compared to only 17 percent for mammals and 15 percent for birds. The American Fisheries Society estimates that 72 percent of our mussels need protection. The precipitous decline of freshwater mussels in the 20th century is unparalleled in our nation's history, and many more extinctions are likely without a coordinated conservation effort.

Freshwater mussels serve important ecological roles. They are a food source for many aquatic and terrestrial animals. They improve water quality by filtering contaminants, particulates, and excess nutrients from our rivers. Sensitive to toxic chemicals, they serve as an early warning of water quality problems before other biological resources are noticeably affected.

The economic value of some of the more common species is also significant. Native mussel shells are used in the cultured pearl and jewelry industries. In 1993, the mussel shell industry in the United States exported roughly 6,500 tons of shells. The annual Value to the mussel shell industry has been estimated at $40 to $50 million, and the shell harvest provides employment to about 10,000 residents, primarily in the Mississippi River basin.

Although biologists have been documenting mussel declines since the early part of this century, only in the last 25 years have environmental laws been available to significantly reduce threats to these animals. Numerous federal, state, tribal, and local agencies; conservation groups; and concerned citizens now recognize the severity of the problem and the vulnerability of freshwater mussels. Many historical and current threats to this fauna are not economically or socially feasible to remedy. However, much can and is being done to help secure a future for this valuable national resource.

Since the early 1980s, the Service's Southeast Regional office, which encompasses an area containing more than 90 percent of the nation's mussel taxa and more than 95 percent of all federally listed mussels (70 species), has actively supported mussel research and conservation initiatives. As a result, the Service's Asheville (North Carolina) Field Office, with its many partners (Alabama Division of Game and Fish, Kentucky Department of Fish and Wildlife Resources, North Carolina Wildlife Resources Commission, Tennessee Wildlife Resources Agency, Virginia Department of Game and Inland Fisheries, U.S. Geological Survey [USGS], U.S. Forest Service [USFS], National Park Service, Natural Resources Conservation Service, Resource Conservation and Development Councils, State Soil and Water Conservation Districts, Tennessee Valley Authority [TVA], Tennessee Aquarium/Southeast Aquatic Research Institute [SARI], and TNC) is poised to implement a major mussel recovery program in the Southern Appalachians and lower Tennessee-Cumberland River ecosystems.

Recent advances in mussel research make it possible to maintain and propagate some endangered mussel species in captivity, and research is underway to develop propagation technology for other listed mussels. Captive propagated mussels can be used to augment existing populations and to reestablish populations into restored historical habitats.

Juveniles of the endangered tan riffieshell (Epioblasma walkeri) have been reared in captivity and for the past 3 years have been released into the Hiwassee River, a Tennessee River tributary in east Tennessee. This project, funded by the Service and the Tennessee Wildlife Resources Agency, is truly a cooperative venture. Gravid female riffieshells were provided by the Virginia Department of Game and Inland Fisheries. The young were produced at Virginia Polytechnic Institute and State University by the Biological Resources Division of USGS. The USFS, USGS, and TVA assisted with identification of the release sites in the Cherokee National Forest, and local school children assisted in the actual release of the juveniles. The Hiwassee River contains an extemely small and currently nonreproducing population of tan riffieshells.