Pygmy Sculpin

Cottus pygmaeus

Description

The pygmy sculpin is a small freshwater fish about 1.8 in (4.6 cm) in length. Its coloration varies by maturity, sex, and breeding condition. Patterning consists of up to three dorsal saddles and spotted fins. Juveniles have a black head and a grayish black body with three light saddles. Mature fish have white heads and lighter bodies, with the gray-ish black color remaining in the form of two saddles. Breeding males become almost entirely black; spots in the dorsal fin enlarge and the margin becomes reddish orange. Breeding females are slightly darker than nonbreeding females.

Behavior

The pygmy sculpin feeds on a variety of insects and small aquatic crustaceans, with isopods being the most important food. The species spawns throughout the year, with a peak occurring in spring and summer. Usually more than one female deposits eggs in batches on the underside of rocks. These nests are probably guarded by the male.

Habitat

This species inhabits a single spring and spring run in Alabama. The spring flow averages 32 million gal (121 million l) per day, with a water temperature between 61 and 64°F (16 and 17.7°C). The bottom of the spring pool and run is gravel and sand; large mats of vegetation occur in both the pool and the run.

Distribution

The pygmy sculpin was discovered in 1968 at Coldwater Spring and the spring run near Anniston, Alabama. The spring has been impounded and forms a one-acre pool, 2-4 ft (0.6-1.2 m) deep. The run is up to 60 ft (18 m) wide and flows for about 500 ft (152 m) where it is joined by Dry Creek. Below this point it is known as Coldwater Creek which flows into Choccolocco Creek. The pygmy sculpin is restricted to the spring and the spring run; it has not been found elsewhere. Coldwater Spring, which is owned by the City of Anniston, is the city's primary water supply, drawing about 16 million gal (60.5 million l) a day.

Threats

The main threats to the pygmy sculpin are groundwater contamination, the adverse impacts of highway construction on the source aquifer, and the species' restricted range.

Both the surface water and the underground aquifer have shown some degree of toxic contamination. The Anniston Army Depot is nearby and studies have indicated that toxic chemicals, including chlorinated hydrocarbons, phenols, and hexavalent chromium, have been found in groundwater at the depot. Although migration of these compounds is not an immediate threat, they may sink into the aquifer and have a future impact on the water quality of Coldwater Spring. The spring water itself contains high levels of trichloro-ethylene.

The Alabama Highway Department plans to construct a highway bypass from Interstate 20 to Anniston. Three alternative routes for the bypass have been proposed. The preferred route would run along the side of Coldwater Mountain, just above and to the east of Coldwater Spring. The use of explosives in cutting a mountain road might change the system of cracks and fissures that route water to and from the underground aquifer, thus affecting Coldwater Spring. The two other proposed routes present less risk to the spring.

Since only a single population of the pygmy sculpin is known to exist, the species is vulnerable to an unpredictable human or natural event. A toxic spill that would contaminate the spring's source aquifer is perhaps the most dangerous potential threat of this type.

Conservation and Recovery

The U. S. Fish and Wildlife Service published a Recovery Plan for the pygmy sculpin in 1991. The critical habitat of the threatened fish in Coldwater Spring and its run is owned and protected by the Anniston Water and Sewer Department. The key to the survival of the pygmy sculpin is the protection of the quantity and quality of groundwater in the recharge aquifer of its critical habitat. This means that threatening activities that could degrade hydrology or water chemistry must not be permitted. This protection is undertaken normally, since Cold-water Spring is the principal water supply of the town of Anniston. In addition, the populations of the pygmy sculpin should be monitored, and research undertaken into its biology, habitat needs, and beneficial management practices.

Contacts

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

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

References

Mount, R. H. 1986. "Vertebrate Animals of Alabama in Need of Special Attention." Alabama Agricultural Experiment Station.

U. S. Fish and Wildlife Service. 1991. "Pygmy sculpin (Cottus pygmaeus ) Recovery Plan." Jackson, Mississippi.

Williams, J. D. 1968. "A New Species of Sculpin, Cottus pygmaeus, from a Spring in the Alabama River Basin" Copeia 1968:334-342.