Yellowcheek darter (Etheostoma moorei)
|Also known as:||Yellow-cheeked darter|
|Size||Length: c. 5 cm (2)|
Maximum length: 6.4 cm (3)
Classified as Vulnerable (VU) on the IUCN Red List (1).
The yellowcheek darter is a rare species of freshwater fish found only in the State of Arkansas in the United States. For most of the year the yellowcheek darter is predominately grey with contrasting dark brown, saddle-shaped patches on the sides. However, during the breeding season the male develops a brilliant blue breast and throat and a light green underside, while the smaller, and somewhat duller, female develops a scattering of orange-red spots (3). The body is deep and slender with a sharp, straight snout and two separate dorsal fins and, in common with other darters, the yellowcheek darter lacks a swim bladder, a gas-filled sac typically used to regulate buoyancy (3) (4) (5). Adapted to a bottom-dwelling lifestyle, the yellowcheek darter dashes between the sanctuary of large stones, a behaviour that has earned the species its common name (5).
The yellowcheek darter is endemic to four tributaries of the upper Little Red River drainage in Arkansas State in the southern United States (1) (3).
The yellowcheek darter is found in small to medium-sized, fast flowing rivers and streams. It prefers areas with clear water, rocky or gravel bottoms and a steep gradient, and is often found in areas with dense growths of aquatic plants (3) (6). Adults are typically found in waters with a depth of 25 to 50 centimetres, but juveniles prefer more shallow waters (6).
A rare and little-studied species, much of the yellowcheek darter’s biology is, as yet, undescribed (3). However, this bottom-dwelling fish is known to feed on a variety of invertebrates, including immature mayflies and stoneflies (6). A fairly sedentary species, the yellowcheek darter rarely strays from its home grounds, but during the breeding season mature fish move towards small, fast flowing streams to breed. It is at this time that the female fish bury into the substrate with only the head and tail fin exposed. The male then positions above the female to fertilise the eggs as they are released (3).
Although once abundant, the yellowcheek darter population has undergone a rapid decline, decreasing by 75 to 90 percent since the 1960s (3) (6). The principle agent behind this decline was the creation of Greers Ferry Lake in 1962, which resulted in the inundation of downstream tributaries, creating deep pools with increased sedimentation and lower oxygen levels in the water. As an inhabitant of shallow, fast-moving streams the yellowcheek darter was displaced from much of its former range, moving upstream to less suitable areas of habitat. The species’ migratory behaviour was also disrupted, while the loss of downstream refugia made the species more vulnerable to droughts, resulting in the loss of many populations (7). Other threats, such as the channelization of streams for agriculture and human consumption, have isolated some populations, and a loss of genetic diversity has been observed due to inbreeding (3) (8).
Having suffered such a severe decline, the yellowcheek darter is in drastic need of major conservation measures. Indeed, the species has been proposed for Threatened Status under the U.S Endangered Species Act (9). An agreement has also been made between several conservation organisations and landowners to mitigate threats to the species, protect bordering terrestrial habitats; and explore potential reintroduction programmes (3). In conjunction with this, several mature adults were taken from the wild in 2002 to start a captive breeding programme, with the first individuals bred in 2003 and further successes in 2006 (10).
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- Dorsal fin: the unpaired fin found on the back of the body of fish, or the raised structure on the back of most cetaceans.
- Endemic: a species or taxonomic group that is only found in one particular country or geographic area.
- Fertilisation: the fusion of gametes (male and female reproductive cells) to produce an embryo, which grows into a new individual.
- Genetic diversity: the variety of genes within a particular species, population or breed causing differences in morphology, physiology and behaviour.
- Inbreeding: the breeding of closely related individuals. An inbred population usually has less genetic variability and this is generally disadvantageous for its long-term survival and success.
- Invertebrates: animals with no backbone, such as insects, crustaceans, worms, molluscs, spiders, cnidarians (jellyfish, corals, sea anemones), echinoderms, and others.
IUCN Red List (April, 2010)
FishBase (April, 2010)
U.S.Fish and Wildlife Service. (2008) Species Assessment and Listing Priority Assignment Form. U.S. Fish and Wildlife Service. Available at:
- Raney, E.C. and Suttkus, R.D. (1964) Etheostoma moorei, a new darter of the subgenus Nothonotus from the White River system, Arkansas. American Society of Ichthyologists and Herpetologists, 1964: 130-139.
- Campbell, A. and Dawes, J. (2004) Encyclopedia of Underwater Life. Oxford University Press, Oxford.
NatureServe Explorer (April, 2010)
- Wine, M.S., Weston, M.R. and Johnson, R.L. (2008) Density dynamics of a threatened species of darter at spatial and temporal scales. Southeastern Naturalist, 7: 665-678.
- Johnson, R.L., Mitchell, R.M. and Harp, G.L. (2006) Genetic variation and genetic structuring of a numerically declining species of darter, Etheostoma moorei Raney & Suttkus, endemic to the upper Little Red River, Arkansas. The American Midland Naturalist, 156: 37-44.
U.S. Fish and Wildlife Service (April, 2010)
Conservation Fisheries (April, 2010)