Etheostoma spilotum

Thomas et al. (2023) present multiple lines of evidence supporting the recognition of Etheostoma spilotum and E. sagitta as distinct species, with a revised diagnosis and redescription of E. spilotum. Previously, Page and Burr (2011) and Catalog of Fishes (as of early 2012) recognized E. spilotum as a distinct species, however, Page et al. (2013) did not accept this change.

This species has undergone a substantial long-term decline and is extirpated from approximately 50% of the historically occupied streams. Its habitat in many areas has been severely degraded as a result of coal mining, oil and gas exploration, and logging. It now occurs in 52 streams in the upper Kentucky River drainage in Kentucky and is moderately common in some areas.

This species is restricted to the upper Kentucky River basin in eastern Kentucky, USA, where it occupies upland streams on the Cumberland Plateau. The distribution extends from the Red River upstream including Sturgeon Creek and the North, Middle, and South forks of the Kentucky River (Thomas et al. 2023). Approximately 90% of the species’ range lies within the Central Appalachian ecoregion, and a smaller portion of populations along the northern and western edge of the range lies within the Western Allegheny Plateau ecoregion (Thomas et al. 2023). Using extant NatureServe (2026) occurrence records, range extent is estimated to be 5,140 km² (RARECAT 2025).

This species is represented by a fairly large number of occurrences (subpopulations) and locations. It is reported to be extant in 52 streams in the following Kentucky River tributaries (and smaller tributary watersheds): (1) Red River (Rock Bridge Fork of Swift Camp Creek); (2) Sturgeon Creek (Travis, Wild Dog, and Granny Dismal creeks); (3) Silver Creek; (4) North Fork Kentucky River (Troublesome, Quicksand, Frozen, Holly, Lower Devil, Walker, and Hell creeks); (5) Middle Fork Kentucky River (Big Laurel, Rockhouse, Hell for Certain, and Squabble creeks); and (6) South Fork Kentucky River (Red Bird River, Hector Branch, and Goose, Bullskin, Buffalo, and Lower Buffalo creeks) (USFWS 2022, Thomas et al. 2023). The largest cluster of occurrences is within the Red Bird River watershed (South Fork Kentucky River drainage) (Thomas et al. 2023). Blanton et al. (2019) found the species to consist of 9 genetically distinct populations.

This darter can tolerate moderate siltation, but heavy siltation and acid runoff from regional surface mining for coal has eliminated many populations (Page and Burr 1991, Etnier and Starnes 1993, Hitt et al. 2016). All of the range is in coal-producing areas (Etnier and Starnes 1993). USFWS (2022) noted there are 97 active surface mining permits in this species' range. High conductivity, which negatively impacts intercellular ion-transport mechanisms regulating osmoregulation and acid/base balance, caused by sulfate pollution from coal mining has been shown to decrease abundance of this species (Hitt et al. 2016, Blanton et al. 2019). High conductivity can even make affected stream segments unsuitable for this species and effectively creates habitat fragmentation within a single stream (Blanton et al. 2019, Watson et al. 2024). Loss of only 10% forest cover can cause declines in abundance and even fragment habitat in streams (Culley et al. 2025). Runoff pollution, stream channelization, and any number of causes of sedimentation also reduce abundance of this species (USFWS 2010, Hitt et al. 2016, USFWS 2022, Watson et al. 2024). Severe flooding from increasingly severe thunderstorms is suspected of negatively impacting local populations (USFWS 2022).

USFWS (2010) summarized threats as follows: Habitat has been severely degraded and limited by water pollution from surface coal mining and gas exploration activities; removal of riparian vegetation; stream channelization; increased siltation associated with poor mining, logging, and agricultural practices; and deforestation of watersheds. These threats are (1) widespread across the range; (2) imminent (the effects are manifested immediately and will continue); and (3) severe (stressors are of high intensity or high strength and can lead to mortality). The severity (or intensity) of these threats, especially impacts from mining and gas exploration activities, is high - these activities can permanently alter stream water quality (e.g., elevated conductivity) by contributing sediment, dissolved metals, and other solids to streams supporting populations. These water quality changes can be permanent and render these habitats unsuitable for the darter. Recent and past research has demonstrated that this darter is intolerant of these conditions, and it has been eliminated from a number of streams across its range. Current regulatory mechanisms have been inadequate to prevent these impacts. The small, remnant nature of many populations may prohibit the natural interchange of genetic material between these populations, and the small population size may reduce the reservoir of genetic diversity within populations. This can lead to inbreeding depression and reduced fitness of individuals. It is possible that some populations are below the effective population size required to maintain long-term genetic and population viability. No available information indicates that the magnitude or imminence of these threats is likely to be appreciably reduced in the foreseeable future.