Maryland Darter

Etheostoma sellare

Description

The silvery Maryland darter, Etheostoma sellare, reaches a maximum length of about 2.8 in (7 cm). It can be distinguished from closely related darters by four dark saddles across its back and a small dark spot behind the lower rear margin of its eye. The saddles may be poorly developed in juveniles and appear as a series of X-shaped blotches on the sides. The largest captured specimen may have been four years old.

Behavior

The Maryland darter is believed to spawn in late April or early May. Reproduction is probably similar to other members of its genus, which prefer riffle areas over a gravel substrate for spawning. The darter feeds on snails, insect larvae, aquatic insects, and some plant matter.

Habitat

Most specimens have been found in shallow riffle areas over a gravel or silt bottom in a single drainage system in Maryland. Normal flow velocities for streams in this basin are slight, scarcely maintaining a flow under drought conditions. Rooted aquatic plants are riverweed and water moss.

Distribution

The Maryland darter was originally described in 1913 from specimens collected in Swan Creek adjacent to Gasheys Run near Aberdeen, Maryland. It is believed to have once been more abundant in the lower Susquehanna River drainage.

The Maryland darter has been found only in the lower Susquehanna River basin near Aberdeen and Havre de Grace, Maryland, in Deer Creek, Swan Creek, and Gasheys Run. Biologists believe that the Deer Creek population may currently be the only viable population. Very few recent sightings of this species have been made. Field surveys at various locations in the early 1980s found only from one to 10 individuals at any location and no individuals have been observed since 1988.

Threats

The Maryland darter's range was reduced when the Susquehanna River was dammed in the twentieth century, causing extensive siltation, pollution, and water withdrawals of darter habitat. Associated threats are oxygen reduction and alteration of water temperature. It is probable that the lack of suitable habitat prevents the darter from breeding in Gasheys Run and that darters found there are stragglers from the Deer Creek population. Populations in Deer Creek are potentially threatened by high turbidity caused by erosion and siltation; impoundments; insecticide, herbicide, and fertilizer runoff; and sewage plant malfunction resulting in flooding or untreated sewage being introduced into the stream.

Conservation and Recovery

The U. S. Fish and Wildlife Service has designated Critical Habitat for the Maryland darter to include: the Deer Creek main channel from Elbow Branch to the Susquehanna River; and Gasheys Run main channel from the Penn Central Railroad crossing south to Swan Creek. The most immediate threats to the Maryland darter are runoff into Deer Creek containing excessive nutrients or wastes and the possible construction of other dams and impoundments that would increase water turbidity. The Recovery Plan calls for monitoring water samples of the Susquehanna River drainage and upper Chesapeake Bay tributaries; restricting collection permits; establishing a state-owned refuge at the Deer Creek rifle; controlling water flows and water quality; and reducing sedimentation from road maintenance, construction, and agricultural pollution.

Contact

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

References

Collette, B. B., and L. W. Knapp. 1966. "Catalog of Type Specimens of the Darters (Pisces, Percidae, Etheostomatini)." Proceedings of the U.S. Natural History Museum 119(3550):1-88.

Knapp, L. 1976. "Redescription, Relationships and Status of the Endangered Maryland Darter, Etheostoma sellare (Radcliffe and Welsh)." Proceedings of the Biological Society of Washington 89(6):99-117.

U. S. Fish and Wildlife Service. 1985. "Revised Maryland Darter Recovery Plan." U.S. Fish and Wildlife Service, Newton Corner, Massachusetts.