Bluemask Darter (Etheostoma [Doration] sp.)

The bluemask darter is a small (1.8 inches), slender fish that is only found in the Caney Fork River system (above Great Falls) in central Tennessee. Breeding males are nearly covered by a bright blue color, which is especially concentrated on the lower portions of the face and body. This darter can be found in streams where the water current is slow to moderate, water depths range from 4 to 20 inches, and the stream bed is composed of sand and fine gravel. The largest population occurs in the Collins River. Populations in Cane Creek, Rocky River, and the Caney Fork River appear to be small and restricted to very short stream reaches. All populations have been isolated since 1916 when the Great Falls Reservoir was filled.

Range Maps

The most significant factor contributing to the bluemask’s darter decline was likely the building of the Great Falls Dam. The reservoir impounded by the dam flooded over 50 miles of possible bluemask darter habitat and isolated the tributary populations from each other. Populations have also been reduced by such factors as the general deterioration of water quality resulting from siltation and other pollutants contributed by coal mining, gravel mining, poor land use practices, water withdrawal, and waste discharges.

Little is known about the life history of the bluemask darter. The closely related speckled darter (Etheostoma stigmaeum) spawns in the early spring and buries its eggs in gravel. Darters, as their name implies, dart about on the bottoms of streams and eat small crustaceans and insects. Darters are often unseen by the general public, largely because of their small size. Darters are native only to North America with over 150 different species. Seventeen species of darters are federally listed as threatened or endangered in the United States. Seven of the federally listed darters occur in Tennessee, including the bluemask darter.

The Service is currently determining the status of the known bluemask darter populations and documenting life history information. The recovery criteria for this species indicate that the species will be considered for downlisting from endangered to threatened when three viable populations are established. To define "viable" populations, information on size and age distribution, sex ratios, recruitment, and mortality rates must be collected over an extended period of time. If you are interested in learning more about this fish or the Service’s effort to protect it, please contact Timothy Merritt at 931-528-6481, ext. 211, or via email at timothy_merritt@fws.gov.