Slender Chub

Erimystax cahni

Description

The slender chub, Erimystax (=Hybopsis) cahni, has a moderately elongated body and reaches a maximum length of about 3 in (7.7 cm). It has a long snout, large eyes, and a slightly underhanging mouth. Olive to brown above, it has silvery sides, a whitish underside, and a dark lateral stripe.

Behavior

Little is known of the slender chub's reproductive behavior. Spawning probably begins in mid to late April and extends into early June. Young mature in three to four years and die shortly after. It feeds primarily on insects and mollusks.

Habitat

From April to September the slender chub inhabits large warm streams, 100-413 ft (30-125 m) wide, which have wide shoals of clean gravel. The fish's winter habitat is unknown.

Distribution

The slender chub is endemic to the upper Tennessee River basin and has been recorded from the Clinch, Powell, and Holston rivers. It was collected from the Holston River only one time, in 1941, and has not been seen there since.

The slender chub has one of the smallest ranges of any eastern North American minnow. Today, it is found in nine population centers on the Powell and Clinch Rivers in Tennessee and Virginia. It occurs in sections of the main channel of the Powell River from Lee County, Virginia, downstream to Norris Lake, Tennessee. In the Clinch River it is found in localized populations from Scott County, Virginia, downstream to Norris Lake.

Threats

The Holston River population was lost when the Cherokee Reservoir was completed by the Tennessee Valley Authority (TVA) in the 1940s. The river above the reservoir is now silted and polluted by industrial discharges from Kingsport, Tennessee. The habitat below the reservoir is affected by cold water releases. Clinch River populations have also suffered from reservoir development and from chemical spills and discharges in the 1960s and 1970s.

The Powell River headwaters arise in the heart of coal mining country, and the affects of runoff from the mines are evident in the river and its tributaries. Coal silt has been measured as deep as 3.3 ft (1 m) in pools and backwaters at McDowell Ford. These conditions are only expected to worsen in the near future. Gravel shoals in the Clinch and Powell rivers have been dredged, further disturbing slender chub habitat.

Conservation and Recovery

The recovery of the slender chub and other aquatic life in the Powell River hinges entirely on the cooperation of mining companies in decreasing coal silt runoff into the streams. Other impacts that should be monitored include toxic spills, pesticides, herbicides, siltation from road construction, and decreased water flow due to slurry pipelines. The TVA, the Tennessee Wildlife Resources Agency, the Tennessee Heritage Program, and the Virginia Commission of Game and Inland Fisheries have consulted to determine the adequacy of existing legislation for lessening contamination in the Upper Tennessee watershed.

It is possible that successful reintroduction of the fish back into its historic range can occur once the Holston River has been stabilized. Portions of the habitat may have to be rehabilitated before the expansion or reintroduction of populations can occur. Protecting existing populations is essential to any potential success of introduced fish.

Contacts

Regional Office for Endangered Species
U.S. Fish and Wildlife Service
1875 Century Blvd., Suite 200
Atlanta, Georgia 30345
http://southeast.fws.gov/

Regional Office for Endangered Species
U. S. Fish and Wildlife Service
300 Westgate Center Dr.
Hadley, Massachusetts 01035
http://northeast.fws.gov/

References

Burkhead, N. M., and R. E. Jenkins. 1982. "Five-year Status Review of the Slender Chub, Hybopsis cahni, a Threatened Cyprinid Fish of the Upper Tennessee Drainage." U.S. Fish and Wildlife Service Report. Newton Corner, Massachusetts.

U. S. Fish and Wildlife Service. 1983. "Slender Chub Recovery Plan." U.S. Fish and Wildlife Service, Atlanta.