FAMILY: Unionidae STATUS: Endangered, Federal Register, November 14, 1988 DESCRIPTION: The little-wing pearly mussel measures only 1.5 inches (3.8 centimeters) in length and O.5 of an inch (1.3 centimeters) in width. Its outer shell is usually eroded, presenting a chalky or ashy white appearance.When uneroded, the natural shell color is light green or dark yellowish brown with dark rays of varying length across the front. Most aspects of the species' ecology and reproductive cycle are unknown; but, the little-wing probably reproduces like other adult freshwater mussels. Males release sperm into the water which then is drawn into the female's gills during feeding and respiration.Fertilized eggs remain in the gills until the larvae fully develops, and are released into the water.Following their release, the larvae attach to a fish host, develop, and drop to the streambed as a juvenile mussel. Gravid female mussels have been observed in September and October and spent females in March (Ahlstedt 1986.)Observations indicate that the little-wing may breed over the winter, holding its larvae from midsummer until the following spring (Ahlstedt 1986).Although the fish host(s) is still unknown, the banded sculpin (Cottus carolinae) and the redline darter (Etheostoma rufilineatum) are sometimes found in the same habitat as the little-wing (Ahlstedt 1986). RANGE AND POPULATION LEVEL: Only 17 live mussels were found in six short stream reaches of the Tennessee and Cumberland river basin during an extensive survey in 1986.Over 55 potential or historic habitat areas were searched.The species, always rare, is now known to exist in only three sites in southeastern Kentucky, two in southwestern Virginia, and one in central Tennessee.The largest and healthiest population of the species (7 individuals) is found in Horse Lick Creek, Jackson and Rockcastle Counties, Kentucky.This population extends at least 1O creek miles from the mouth of White Oak Creek upstream to Clover Bottoms (U.S. Fish and Wildlife Service 199O).The other two Kentucky sites are located in the Big and Little South Forks of the Cumberland River, McCreary and Wayne Counties.The two Virginia locations are in the Clinch River in Tazewell County, and in the North Fork Holston River in Smyth and Washington Counties, Virginia.In Tennessee, the species is found in Cane Creek, Van Buren County. Historically, the little-wing mussel was known from 27 stream reaches in the Tennessee and Cumberland River Systems.In Kentucky the species once inhabited Rockcastle River, Laurel amd Rockcastle Counties; Buck and Pitman Creeks, both in Pulaski County; and the West Fork Red River in Todd County.Virginia had several historic sites: the South Fork Holston River in Washington County; the Middle and North Forks of the Holston River, Smyth and Washington Counties; Big Mocassin and Copper Creeks, both in Scott County; and Flag Pond, Wallen's Creek, and Powell Rivers, all in Lee County.In Tennessee, the species was known from Collins River in Warren County; Stones River in Rutherford County; the Duck River; and the Elk River at Estell Spring in Franklin County, Tennessee.The little-wing was also present in Blue Water Creek, Lauderdale County, Alabama, and in Valley Creek, Cherokee County, North Carolina, but has been extirpated from both these locations (U.S. Fish and Wildlife Service 199O). HABITAT: Ideal habitat conditions for the little-wing mussel are found in small or medium, cool, high to moderate gradient streams with low turbidity.Individual mussels are usually found in the transition zone between pools and riffles (Department of the Interior 199O; U.S. Fish and Wildlife Service 1990). REASONS FOR CURRENT STATUS: Deterioration of water quality, particularly from acid mine drainage, is one of the primary threats to the little-wing.The lower portion of the Little South Fork Cumberland River is being polluted by drainage from abandoned, mined lands.When this river was surveyed in 1986, only three live and 126 dead individuals were found above Kentucky State Highway Route 92 Bridge downstream to Freedom Church Ford (Ahlstedt 1986). Additional surveys, conducted in 1987 and 1988, indicate that the species may be extirpated downstream of the Route 92 bridge and may only survive in limited numbers upstream (U.S. Fish and Wildlife Service 199O).Another federally-listed, endangered mussel, the Cumberland bean pearly, has also been seriously impacted by pollution in this same river reach.In fact, Lick Creek, a Little South Fork Cumberland River tributary, is polluted with high concentrations of dissolved solids, sulphates, aluminum, iron, and manganese.During the last survey of Lick Creek, 52 dead and no live individuals were found below the creek (U.S. Department of the Interior, 199O). The little-wing also appears to be more sensitive to pollutants and/or other habitat changes than other mussels.For example, although a large portion of the Big South Fork Cumberland River is polluted by siltation and acid mine drainage, the endangered Cumberland bean pearly and 14 other mussel species survive within a 1O-mile river reach.A good population of the little-wing mussel covers only 2.1 miles of the same reach, located within the Big South Fork National River and Recreation Area, Kentucky.Even Horse Lick Creek, Kentucky, which probably has the best population and habitat conditions, may soon be affected by the exploration and development of oil, gas, and coal deposits already occurring within its watershed. Other threats to the species include impoundments, mussel die-offs, and the isolation between its populations.The little-wing population in Cane Creek, Tennessee, is restricted to less than 2 river miles.Downstream of this population is impounded by the Great Falls River; upstream is large boulder habitat which is unsuitable.In addition, freshwater mussel die-offs have been reported throughout the Mississippi River basin, including the Tennessee River and all of its tributaries.As yet, the problem does not appear to have spread to river reaches containing this species; but, there is a potential for significant losses.All little-wing populations are extremely limited in size and number.This isolation automatically limits the species gene pool and restricts the species' adaptibility to environmental changes. MANAGEMENT AND PROTECTION: The primary recovery goal for the little-wing mussel involves the establishment and maintenance of 13 viable populations within the Tennessee and Cumberland River Systems.This may be accomplished through the management and protection of the six existing populations and by reintroductions into suitable habitat throughout the species' range.To implement these actions, more research is needed on the species' reproduction, food habits, age and growth, fish host(s), habitat requirements, and adaptibility.Once the data are gathered, management and protection efforts can be initiated.Meetings should be scheduled with Federal, State, business, industry, coal-mining, and municipal authorities to discuss the species' environmental needs and develop cooperative protection efforts. REFERENCES: Ahlstedt, S.A.1986.A Status Survey of the Little-wing Pearlymussel (Pegias fabula) (Lea 1838).Report Submitted in Fulfillment of U.S. Fish and Wildlife Service Contract No. 14-16-OOO4-84-927. 38 pp. Department of the Interior, U.S. Fish and Wildlife Service. November 14, 1988. Endangered and Threatened Wildlife and Plants: Determination of Endangered Species Status for the Little-wing Pearly Mussel.Federal Register 53:219:45861-45865. U.S. Fish and Wildlife Service.Technical/Agency Draft Recovery Plan for Little-wing Pearly Mussel (Pegias fabula).U.S. Fish and Wildlife Service, Atlanta, Georgia.42 pp.