Lepidomeda copei

The generic allocation of leatherside chubs has been unstable. The original name was Squalus copei; subsequently the species was placed in six other genera. Uyeno (1960, Ph.D. diss., Univ. Michigan) restudied taxonomy and placed it in genus Gila, subgenus Snyderichthys (Lee et al. 1980). Starnes (1995) treated Snyderichthys as a full genus and referred to this species as S. copei; he noted that the populations in separate subbasins of the Bonneville Basin system should be investigated for polytypy.

Simons and Mayden (1997) presented reasons for recognizing Snyderichthys as a genus rather than as a subgenus of Gila.

Dowling et al. (2002) studied cytochrome b gene sequences and found that Snyderichthys from the Snake and Bear River drainages is part of a clade that includes Lepidomeda mollispinus and L. albivallis, casting doubt on the validity of morphologically diagnosed Snyderichthys. Based on the molecular data and a possible biogeographic scenario, Dowling et al. (2002) indicated that Snyderichthys may become a synonym of Lepidomeda, and that Snyderichthys from the central and southern Bonneville basin may warrant recognition as a distinct species, possibly L. aliciae (Jouy, 1881). However, Dowling et al. (2002) noted that further study is needed.

Nelson et al. (2004) cited Simons and Mayden (1997) as a basis for listing Snyderichthys as a valid genus. They did not mention the work of Dowling et al. (2002).

Johnson et al. (2004) found that the leatherside chub is composed of two reciprocally monophyletic clades characterized by numerous fixed genetic differences for both mitochondrial and nuclear DNA markers. The clades also showed significant differences in cranial shape, and controlled growth and foraging experiments show that the clades appear to be locally adapted to the thermal environments where they now occur. Combined, these three lines of evidence support the hypothesis that leatherside chub is composed of two species. Moreover, all lines of evidence place these two species within the genus Lepidomeda. Johnson et al. (2004) therefore recognized the two clades of leatherside chub as two distinct species (Lepidomeda copei in the north and L. aliciae in the south), and they argued that each warrants independent conservation and recovery action.

Small range in upper Snake River and Bear River drainages in Wyoming, Idaho, and Utah; has declined significantly from historical levels; most extant populations are apparently secure.

Range includes tributaries of the upper Snake River and Bear River drainages, northern Utah, Wyoming, Idaho, and (historically) Nevada (Johnson et al. 2004, USFWS 2011). Two populations in the Upper Green River subregion in the Colorado River region may have resulted from introductions by humans (USFWS 2011).

USFWS (2011) found that 14 extant northern leatherside chub populations persist across 3 subregions: 7 populations in the Bear River subregion; 5 populations in the Snake River subregion; and 2 (likely non-native) populations in the Green River subregion. Criteria for recognition of a population were as follows: presence of multiple age classes, collection of a dense number of fish (more than five individuals), and documentation of fish collections over multiple years (USFWS 2011).

Populations reportedly have been severely impacted by irrigation projects, impoundments, dewatering, and siltation; predation by introduced brown trout apparently excludes chubs from favored microhabitats (Walser et al. 1999). This is a good bait minnow but too rare in Wyoming to be of importance (Baxter and Stone 1995). Sigler and Sigler (1987) remarked that at one time, use as a bait minnow depleted the population.

USFWS (2011) determined that that five of fourteen populations within the species' current range could be considered to have concentrated threats. However, USFWS (2011) found "no information that livestock grazing, oil and gas development, mining, water development, water quality, or fragmentation of populations may act on this species to the point that the species itself may be at risk, nor is it likely to become so. While these factors individually have been shown to affect one or a few extant populations of northern leatherside chub, none is considered a significant threat to the species' persistence. For example, stable, reproducing northern leatherside chub populations occur at many locations where degraded habitat conditions exist. While these habitat characteristics may not be optimal for northern leatherside chub populations, their continued persistence and successful reproduction demonstrate that they have some level of tolerance for less than optimal environmental conditions. Because of the sufficient number of populations, the interaction between several population locations, and the large size of many populations, we conclude that local extirpation risk to a small number of populations does not constitute a substantial threat to the species. The best scientific and commercial information available indicates that rangewide the northern leatherside chub is not threatened by the present or future destruction, modification, or curtailment of its habitat or range, nor is it likely to become so."

Further, USFWS (2011) determined that the northern leatherside chub is not threatened by overutilization for commercial, recreational, scientific, or educational purposes, nor is it likely to become so. USFWS (2011) reported that they found "no information that indicates that the presence of parasites or disease significantly affects northern leatherside chub, or is likely to do so. There is strong evidence that northern leatherside chub can be impacted by predation from nonnative trout, especially brown trout. Nonnative trout currently occur near or downstream to 5 of 14 northern leatherside chub populations. While these populations are more vulnerable to predation and other effects from nonnative trout, we have no information that indicates nonnative trout are currently impacting these populations or the species as a whole. We found no information that disease or predation may act on this species to the point that the species itself may be at risk, nor is it likely to become so." "Available information indicates that land management regulatory mechanisms are sufficiently minimizing and mitigating potential threats from land development to extant northern leatherside chub populations" (USFWS 2011).

USFWS (2011) also reported: "Recent examination of northern leatherside chub from habitats where suspected hybrids were historically found has determined that hybridization is not present. Therefore, with no known instances of hybridization, we conclude that hybridization is not a threat to northern leatherside chub. Projected impacts from future climate change effects will likely impact all northern leatherside chub populations to some degree, although the synergistic effect of these impacts with identified and potential threats are uncertain. Because stable, reproducing northern leatherside chub populations occur at many locations where degraded habitat conditions exist, their continued persistence and successful reproduction demonstrates that they have some level of tolerance for less than optimal environmental conditions. We found no information that other natural or manmade factors affecting its continued existence may act on this species to the point that the species itself may be at risk, nor is it likely to become so."