Loading profile. Please wait . . .
Moxostoma ugidatli Jenkins, Favrot, Freeman, Albanese, and Ambruster, 2025
Sicklefin Redhorse
Federal Protection: No US federal protection
State Protection: Endangered
Global Rank: G1G2
State Rank: S1
Element Locations Tracked in Biotics: Yes
SWAP 2015 Species of Greatest Conservation Need (SGCN): Yes
SWAP 2025 Species of Greatest Conservation Need (SGCN): Yes
2025 SGCN Priority Tier: Highest Conservation Concern
Element Occurrences (EOs) in Georgia: 4
Habitat Summary for element in Georgia: Riffles, runs and pools in large creeks and small to medium-sized rivers. Juveniles may also occur in reservoirs downstream of spawning sites
This is a large, distinctive sucker with a sickle-shaped (falcate) dorsal fin that is prominent in both juveniles and adults. Adults may exceed 500 mm (20 inches) total length and females grow larger than males. Both lips are divided into longitudinal sections (plicae); these sections are more deeply divided and branching on the lower lip compared to other redhorse species. The posterior edge of the lower lip is slightly angled to straight. Pharyngeal arch includes both comb-like and molariform teeth. The head and sides are olive-brown or brassy and the lower sides and belly are silvery to white. The ventral fins are dusky and are often tinted yellow or orange. Both juveniles and adults have a red caudal fin that varies in intensity from faintly brown-red to bright red. Breeding males develop prominent tubercles on their anal and caudal fins and the relative length of their anal and inner pelvic fin rays are longer than in females.
Four other redhorse sucker species occur within the range of the sicklefin redhorse in Georgia: silver redhorse (Moxostoma anisurum), river redhorse (M. carinatum), black redhorse (M. duquesnei), and golden redhorse (M. erythrurum). Most sicklefin larger than about 4 inches standard length can be readily distinguished from all of these species by their longer dorsal fin height and greater dorsal fin concavity. Blue Ridge populations of the black redhorse may have a slightly falcate dorsal fin and reddish caudal fin, but these characteristics are much less pronounced than in the sicklefin redhorse. Adult river redhorse may have a brilliant red caudal fin, but this species is easily separated from the sicklefin redhorse using dorsal fin shape and height.
Sicklefin redhorse typically occur in swift riffles, runs, and pools in large creeks (about 20 m or 60 feet wide) and small to medium-sized rivers (up to 100 m or 300 feet wide) over relatively silt-free, rocky stream bottoms. Although sicklefin redhorse use a variety of microhabitats throughout their life history, this species primarily utilizes areas with swift currents during feeding and spawning. Juveniles are known from the lower reaches of rivers and reservoirs downstream of spawning habitats.
The sicklefin redhorse has been observed grazing over rocky substrates, woody debris and within beds of riverweed (Podostemum ceratophyllum), an aquatic macrophyte. Their diet is dominated by immature aquatic insects. Its moderately molariform pharyngeal teeth may allow it to feed on snails and mussels as well.
The sicklefin redhorse has a fascinating and complex life history, which has been documented for the Hiwassee River population by Robert E. Jenkins and researchers from the North Carolina Cooperative Wildlife Research Unit (Favrot and Kwak 2018). Adults are known to use the mainstem Hiwassee river below Mission Dam, North Carolina for feeding and over-wintering habitat. Males and females reach sexual maturity between ages 5 - 7 and 7 - 8, respectively. The maximum known age is 22 years. Adults migrate into larger tributary streams, including Georgia portions of Brasstown Creek, to spawn in the spring (late March-May) when water temperatures are 10-18 º C (49-64 º F). Spawning typically occurs over large gravel or small cobble in moderate to swift-flowing runs and riffles. Sicklefins typically engage in group spawning where up to 5 males crowd around one female during a single spawning act. Spawning involves intense quivering which results in the displacement of spawning substrate and the burial of at least some of the eggs. Radio-telemetry studies indicate that adult sicklefin redhorse migrate downstream to larger river habitats after spawning and may temporaily utilize reservoir habitats during migration. Very little is known about the ecology of larvae and juveniles, but their collection from the lower Hiwassee River and Hiwassee lake suggests that they may drift long-distances downstream from spawning sites. Juveniles have not been collected within Brasstown Creek in Georgia, which is consistent with downstream dispersal of larvae and juveniles.
Because of its restricted distribution and vulnerability to harm by electrofishing, please contact the Wildlife Conservation Section before carrying out any electrofishing surveys within Brasstown Creek. With experience, this species can be readily identified by dorsal fin shape while making observations from the stream bank with the naked eye or with polarized binoculars. The Sicklefin Redhorse Conservation Committee has been monitoring the species in Brasstown Creek using a fyke net that captures fishes as they migrate upstream during the spawning season. Captured fishes are injected with a passive integrated transponder (PIT) tag, measured, weighed, sexed, and released in their direction of travel. A PIT tag antenna system, consisting of loop of wire buried in the stream bottom and attached to a data recorder on land, is then used to detect individuals as they migrate over the antenna each year. These data are used in a population model to estimate population size and survival of the Sicklefin Redhorse population in Brasstown Creek.
The sicklefin redhorse is restricted to Blue Ridge portions of the Hiwassee and Little Tennessee river systems in North Carolina and Georgia. Genetic analyses (Moyer et al. 2019) document 2 populations in the Little Tennessee River system (Tuckasegee River and Little Tenneesse River) and a single population in the Hiwassee. In Georgia, it is only known from Brasstown Creek (Hiwassee River tributary), from the town of Young Harris in Towns County downstream to the North Carolina state line. The Sicklefin Redhorse occurs in the Nottely and Hiwassee Rivers in North Carolina and likely occurred in the Georgia portion of these systems prior to impoundment by Lake Nottely and Lake Chatuge. Recent surveys in the Georiga portion of the Nottely and Hiwassee River systems have failed to detect Sicklefin Redhorse; these two river systems thus represent potential reintroducion sites for the species.
Historically, impoundments have destroyed a large amount of adult feeding and breeding habitat throughout the range of the sicklefin redhorse. Impoundments also fragment populations, which eliminates opportunities for gene flow, colonization after local extinction, and migration to upstream spawning habitats. Failure to follow agricultural best-management practices results in sedimentation and bank destabilization in Brasstown Creek. Commercial and residential development in the North Georgia mountains is also a significant threat.
| Threat 1 | Threat 2 | Threat 3 | |
|---|---|---|---|
| General Threat | Natural system modifications | Pollution | Climate change & severe weather |
| Specific Threat | Dams & water management/use | Domestic & urban waste water | None |
This species is known from only a single population in Georgia occurring within Brasstown Creek from upstream of Young Harris to the North Carolina state line. Adult sicklefins have been observed spawning in Georgia and this population is considered important to the conservation of the species overall. Recent estimates based on capture-mark-recapture data indicate that more than 1000 adult Sicklefin Redhore may migrate into Brasstown Creek during some years (Angela Hsiung, pers. communication).
Most of the Brasstown Creek watershed is privately owned, emphasizing the importance of voluntary conservation efforts by landowners. Farmers can improve instream habitat by excluding cattle from streams and riparian zones. There are many technical assistance and cost-sharing programs that can help farmers implement best-management practices to protect streams. Residential landowners can improve water quality for all aquatic species in Brasstown Creek by maintaining or restoring natural forest cover within riparian zones and by minimizing the use of fertilizers on their lawns. For example, the Brasstown Valley Resort has re-established a 100-foot buffer of native riparian vegetation along the portion of Brasstown Creek that runs through their property. Conservation groups should work cooperatively with developers and local governments to minimize impacts from new home construction and commercial development. Larval and juvenile sicklefin redhorse should also be given proper consideration in reservoir management.
The U.S. Fish and Wildlife Service recently determined that listing under the Endangered Species Act was not warranted for the Sicklefin Redhorse (U.S. Fish and Wildlife Service 2016) due in part to the existence of a Candidate Conservation Agreement (CCA) that funds and implements conservation actions for the species (U.S. Fish and Wildlife Service 2015). The CCA is implemented by the Sicklefin Redhorse Conservation Committee, whose formal members include the Georgia Department of Natural Resources, the North Carolina Wildlife Resources Commission, the Eastern Band of the Cherokee Indians, the Tennessee Valley Authority, the U.S. Fish and Wildlife Service, and Northbrook Energy. Several partnership organizations, including Mainspring Conservation Trust (formerly Hiwassee River Watershed Coalition) and Young Harris College, work collaboratively with the SRCC to meet conservation and research needs for the species in Georgia.
Jenkins, R.E.J. 1999. Sicklefin redhorse Moxostoma sp., undescribed species of sucker (Pisces, Catostomidae)in the upper Tennessee River drainage, North Carolina, and Georgia: description, aspects of biology, habitat, distribution, and population status.Unpublished report to U.S. Fish and Wildlife Service and North Carolina Wildlife Resources Commission, Raleigh.
Favrot, S.D. 2009. Sicklefin redhorse reproductive and habitat ecology in the upper Hiwassee River basin of the Southern Appalachian Mountains. M.S. Thesis, North Carolina State University, Raleigh. 339 pages.
Favrot, S.D. and T.J. Kwak. 2018. Behavior and Reproductive ecology of the Sicklefin Redhorse: an imperiled southern appalachian mountain fish. Transactions of the American Fisheries Society 147:204-222.
U.S. Fish and Wildlife Service 2015. Candidate conservation agreement for the Sicklefin Redhorse. Available online at https://sicklefin.files.wordpress.com/2018/06/cca-sicklefin-redhorse-final.pdf 40 pages.
U.S Fish and Wildlife Service 2016. 12-month findings on petitions to list 10 species as endangered or threatened Species. Federal Register 81 (No. 194 ): 69425-69442.
Brett Albanese
2020. B. Albanese. Incorporation of recent literature and general update of account
