Archive of Featured Species
Featured Species: oyster mussel (Epioblasma capsaeformis)
The oyster mussel is a federally endangered species that historically occurred throughout the Clinch and Powell river drainages of southwestern Virginia and northeast Tennessee. This species is approximately 5 cm (~1.97 inches) in length and yellow-green in color. The oyster mussel is sexually dimorphic, meaning that males and females are markedly different in appearance. Compared to males, females are more inflated and rounded at the posterior end of their shell, characteristics believed to aid in reproduction.
The oyster mussel is a long-term brooder, where spawning occurs in the summer and larvae are held by the female over winter until being released in the spring. Host fish include fantail darters, logperch and banded sculpin. Female oyster mussels have a fleshy flap inside their shell that ranges in color from white to pale blue. Tiny appendages at the top of the flap move, simulating aquatic insect movement, and attract host fish to the mussel. When a female senses a fish near, she closes her shell quickly, trapping the fish. The flaps close around the fish head, acting as a gasket, and the female begins pumping larvae from her gills. After a few minutes the mussel releases her grip, and the fish swims away carrying tiny mussel larvae.
To date, the AWCC has propagated 151,770 juvenile oyster mussels and released 24,961. This species is one of many becoming increasingly rare in the rivers of southwestern Virginia. The oyster mussel was also affected by the coal slurry spill that occurred in Lee County, Virginia in 1996. For propagation purposes, broodstock are collected from the Clinch River in Tennessee where populations are abundant, with the majority of juveniles released in streams in southwestern Virginia.