Cahaba Shiner

Notropis cahabae

Description

Notropis cahabae, Cahaba shiner, is a small, delicate-bodied, silvery-colored fish about 2.5 in (6 cm) long with a peach colored narrow stripe over the dark lateral stripe. This species differs from the minic shiner, a closely related species, by a lateral stripe that does not expand before the caudal spot and by the absence of a predorsal dark blotch. Also, the Cahaba shiner's dorsal, caudal peduncle scales are uniformly dark and pigmented and its peduncle scales are broadly outlined and diffuse.

Behavior

This shiner probably requires a river with sufficient small crustaceans, insect larvae, and algae for food, similar to its close relative, the mimic shiner. The Cahaba shiner seems consistent with other fish in the mimic shiner group, spawning much later than do other North American cyprinids. They appear to spawn from late May through June and seem to have a more limited spawning period than do many fish which reach a rather small adult size.

Habitat

This species' habitat appears to be large shoal areas of the main channel of the Cahaba River. The Cahaba shiner is found in the quieter waters less than 1.6 ft (0.5 m) deep, just below swift riffle areas. The Cahaba shiner seems to prefer patches of sandy substrate at the edge of or scattered throughout gravel beds or downstream of larger rocks and boulders. The Cahaba shiner does not occupy deep water habitats or any other sites other than that of large, shallow shoals.

Distribution

The Cahaba shiner is the only North American large stream fish that is endemic to one main stem of one river. Its entire current range encompasses 60 mi (100 km) of the Cahaba River in Alabama, from 3 mi (5 km) northeast of Heiberger to 3.75 mi (6 km) above Booth Ford. In the recent past, the Cahaba shiner has been collected in about 76 mi (122 km) of the Cahaba River from 3 mi (5 km) northeast of Heiberger in Perry County to Highway 52 bridge near Helena in Shelby County. This range reduction of over 20% occurred between 1969 and 1977. Further reductions in total populations are evident with the stronghold for the species now limited to about 15 river mi (24 river km) between the Fall Line and Piper Bridge or 20% of the historic range. The Cahaba shiner once had a wider historical distribution which may have included the Coosa River.

In 1989 and 1990, in an effort to document population levels, fish were collected at known population sites. Within the stronghold of the species, an average of 3.2 Cahaba shiners were captured, as compared with an average of 38.5 during the period of 1981 to 1986. The ratio of Cahaba shiners to the closely related and more widespread mimic shiner in the earlier sampling was about one to one. In the 1990 survey, the ratio was about 16 mimic shiners to each Cahaba shiner. In addition to the change in ratio, the abundance of both species has decreased, with the Cahaba shiner possibly the less adaptable of the two species.

Threats

Located within the Mobile Basin, the 212 mile Cahaba river supports 132 species and is one of the most diverse, free-flowing rivers of its size in the continent. Lately, however, the populations of several species have severely declined or have been eliminated largely because of pollution. One fish species, the blue shiner, has already been extirpated. Water quality has been degraded from sewage treatment plants, limestone quarries, and strip mining. The effect on the fauna of water rich in dissolved nutrients can be magnified in still pools during low flows and high temperatures when dissolved oxygen drops to low levels. Virtually all of the water flow in some stretches of the Cahaba River during low flows consists of treated sewage effluent. Siltation can have an adverse effect on water quality. Recent fish collections in the Cahaba River have shown a significant decrease in species diversity and numbers of specimens with an apparent increase in siltation. Chlorination from sewage could have an adverse impact on the Cahaba shiner. They are possibly more sensitive to chlorine than other Notropis species.

Methane gas extraction is of considerable interest in the Cahaba River Basin. While preliminary information indicates that the Cahaba shiner can tolerate permitted chloride levels, the potential for the discharge of wastewater from these wells in excess of permitted levels and the impact on the Cahaba shiner is of concern. The impact of other pollutants that may be in wastewater from methane gas wells is unknown.

Conservation and Recovery

The Alabama Department of Conservation and Natural Resources recognizes the Cahaba shiner as an endangered species. In addition, the counties of Perry and Dallas, which border over a third of the Cahaba River's lower main channel, passed resolutions in 1981 establishing scenic corridors as buffer zones. Parties planning activities which might impact the environment in these corridors are required to obtain a permit from their County Commission. A Cahaba River Society, comprised of biologists, conservationists, land-owners and business leaders, has also been organized to protect the river. Since the Cahaba shiner is now a federally-listed, endangered species, Federal agencies are required to ensure that any activities they authorize, fund, or implement are not likely to jeopardize its continued existence. If a Federal action might affect this species, the responsible Federal agency must enter into formal consultation with the U.S. Fish and Wildlife Service.

Contacts

U. S. Fish and Wildlife Service
Jackson Ecological Services Field Office
6578 Dogwood View Parkway, Suite A
Jackson, Mississippi 39213-7856
Telephone: (601) 965-4900
Fax: (601) 965-4340

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

References

Howell, W.M., R.A. Stiles, and J.S. Brown. 1982."Status Survey of the Cahaba Shiner (Notropis D. ) and Goldline Darter (Percina aurolineata ) in the Cahaba River from Trussville to Booth Ford." Alabama

Mayden, R.L., and B.R. Kuhajda. 1989. "Systematics of Notropis cahabae, a New Cyprinid Fish Endemic to the Cahaba River of the Mobile Basin." Bulletin of the Alabama Museum of Natural History 9:16.

Pierson, J.M., W.M. Howell, R.A. Stiles, M.F. Mettee, P.E. O'Neal, R.D. Suttkus, and J.S. Ramsey. Fishes of the Cahaba River System in Alabama. Geological Survey of Alabama.

Stiles, R.A. 1990. "A Preliminary Report on the Current Status of the Goldline Darter, Percina aurolineota, and the Cahaba shiner, Notropis cahabae, in the Little Cahaba and Cahaba Rivers of Alabama." A Report to the U.S. Fish and Wildlife Service.

U.S. Fish and Wildlife Service. 25 October 1990. "Endangered Status Determined for the Fish Cahaba Shiner Notropis cahabae." Federal Register 55(207): 42961-42966.