|Scientific Name:||Lepidomeda mollispinis Miller & Hubbs, 1960|
|Red List Category & Criteria:||Vulnerable B1ab(iii)+2ab(iii) ver 3.1|
|Reviewer(s):||Smith, K. & Darwall, W.R.T.|
|Facilitator/Compiler(s):||Hammerson, G.A. & Ormes, M.|
This species is listed as Vulnerable because extent of occurrence is less than 20,000 sq km, area of occupancy is less than 500 sq km, number of locations is not more than 10, and the habitat remains subject to declines in quantity and quality from flow depletions, water quality issues, and competition and predation by non-native fish species.
|Previously published Red List assessments:|
|Range Description:||Range includes the Virgin River system, Arizona, Nevada, and Utah.(Page and Burr 2011).|
Subspecies mollispinis: Currently, almost all of the occupied habitat is in Utah: mainstem Virgin River above Quail Creek diversion, three reaches in Beaver Dam Wash, Santa Clara River between Veyo springs and Gunlock Reservoir, isolated reaches in Moody Wash and Mogatsu Creek, and a 6.3 km reach in the lower Santa Clara River; also recently fond in the lower reaches of La Verkin, Ash, North, and Shunes creeks, and in the lower reaches of both the North and East forks of the Virgin River; occasionally collected in the mainstem Virgin River between Pah Tempe Springs and Littlefield, Arizona (Federal Register, 18 May 1994).
Subspecies pratensis: Range includes Meadow Valley Wash, Lincoln County, Nevada. Originally known from 1938 collections in the spring outflow and marsh below Big Spring (= Panaca Spring), about 2 km northeast of the town of Panaca (Miller and Hubbs 1960). The area is in a basin off the east side of Meadow Valley Wash, which follows the ancient course of the Pluvial Carpenter River, the main eastern tributary of the Pluvial White River. The Pluvial White River emptied into the Virgin River, which joined the Colorado River at what is presently the Virgin Basin or Overton Arm of Lake Mead. The Big Spring population is thought to have become extinct when the marsh dried up as a result of water diversion. In 1977, a population was discovered in Condor Canyon of Meadow Valley Wash, several km upstream from the type locality (Allan 1983). As of the early 1990s, an 8-kilometre section of Meadow Valley Wash in Condor Canyon was the only known remaining area of occupied native habitat (USFWS 1993, which see for a detailed map). In 1980, an unknown number of juveniles was collected from the pool below the falls in Condor Canyon and transplanted to the stream above the falls (Allan 1985). It is unknown if any occurred historically above the waterfall. An introduced refugium population, established in 1987 in a pond within the BLM's Shoshone Pond Resource Area in White Pine County appears to be extirpated.
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||Subspecies mollispinis: As of 1995, this taxon was extant in the mainstem Virgin River and 11 of its tributaries and subtributaries (Federal Register, 5 April 1995), representing fewer than 10 element occurrences (subpopulations).|
Subspecies pratensis: As of the early 1990s, this taxon was represented by one native occurrence (subpopulation).
Total adult population size is unknown but probably exceeds 10,000. Subspecies mollispinis is locally abundant. Subspecies pratensis was relatively abundant in Condor Canyon in the early 1990s (USFWS 1993).
Annual Virgin Spinedace (subspecies mollispinis) density estimates for each monitoring station in Utah have been highly variable over the period of record; large fluctuations have been observed in both young-of-the-year and adult Virgin Spinedace densities; at many stations these fluctuations are probably caused by spatial and temporal variation in habitat conditions, which in turn are probably related to variations in annual discharge (Wiley et al. 2008). Population monitoring data suggest that further basin-wide declines have been halted and Virgin Spinedace populations are stable in many areas (Wiley et al. 2008).
|Current Population Trend:||Stable|
|Habitat and Ecology:||Habitat includes gravel- and sand-bottomed flowing pools and runs of fast and usually clear creeks and small rivers (Page and Burr 2011); usually in shaded pools (0.5-2.0 meters deep) and runs (Lee et al. 1980); occasionally in riffles in winter (Angradi et al. 1991). Spawning occurs usually at the lower ends of pools on or near the bottom (Minckley 1973).|
|Movement patterns:||Not a Migrant|
Much habitat has been lost due to human impacts, including habitat fragmentation, introduction of non-native fishes, and dewatering associated with agriculture, mining, and urbanization; these continue to threaten populations (USFWS, Federal Register, 18 May 1994, 30 June 1994, see these for further details).
About 40% of the historical habitat has been lost due to human impacts, including habitat fragmentation, introduction of non-native fishes, and dewatering associated with agriculture, mining, and urbanization; these continue to threaten populations (USFWS, Federal Register, 18 May 1994, 30 June 1994, see these for further details).
Wiley et al. (2008) reported that "...much progress has been made to protect and restore Virgin Spinedace populations throughout the Virgin River Basin. Instream flow has been secured in several key reaches, large- and small-scale removal of problematic non-native fish species has occurred, and efforts to purchase, protect, maintain, and improve habitats have been undertaken. In addition Virgin Spinedace reintroductions into several areas of historic habitat have been successful, or shown the potential for success. While climatic conditions, flow depletions, water quality, and stream alterations have presented challenges in certain areas, the efforts of the Virgin Spinedace Conservation Team to improve the long-term status of and habitat for Virgin Spinedace populations will continue." In general, under the conservation agreement and strategy (Lentsch et al. 2002), "threats to Virgin Spinedace habitat have been reduced or controlled..." (Wiley et al. 2008). However, "Flow depletions, water quality issues, habitat degradation, and competition and predation by non-native fish species continue to be problems in certain areas. Limited flow and high water temperatures also threaten the long-term persistence of Virgin Spinedace in many additional reaches during summer low flow periods..." (Wiley et al. 2008).
The Condor Canyon population is vulnerable to a number of threats, including drought, dewatering, erosion and pollution from excess livestock grazing, non-native fishes, and human activities. All of these factors either directly deplete the population or destroy the habitat.
Potential strain on the integrity of the aquifer by regional demands on ground water resources may reduce base flows from Delmue Springs to a point where there is insufficient water on a year-round basis. Interest in exportation of water to southern Nevada metropolitan areas has also arisen.
Cattle grazing occurs within Condor Canyon, both on private and public Bureau of Land Management (BLM) holdings. Livestock grazing could potentially destroy both riparian and aquatic vegetation, thus reducing stream cover and causing stream bank erosion and siltation. The stream could also become eutrophic from excessive cattle urine and feces. When cattle were present in 1988 and 1989, they deposited ammonia in the form of urine and feces, and runoff during winter rainstorms washed additional nitrogen into the system from residual feces (Hall and Amy 1990). The influence of cattle could be seen months after their physical presence when precipitation allowed an influx of nitrogen and phosphorus.
There are four BLM grazing allotments that contain Big Spring spinedace Critical Habitat. These include the N5 (a portion of the Wilson Creek allotment), the Condor Canyon, the Black Hills, and the Highland Peak allotments. The N5 allotment had been in non-use until 1987 when the permittees (Delmue family) requested licensing. This request prompted the BLM to enter into Section 7 consultation with the U.S. Fish and Wildlife Service under the Endangered Species Act of 1973 as amended. It was the opinion of the "Service" that the proposed grazing would not jeopardize the continued existence of Big Spring Spinedace or adversely modify its Critical Habitat. The Condor Canyon allotment is also licensed to the Delmues and has been in voluntary non-use for at least the last ten years (Guerrero 1989). Currently, there is little or no grazing on the Black Hills and Highland Peak allotments; however, during Section 7 consultation with BLM, the U.S. Fish and Wildlife Service concluded that existing or proposed grazing schedules would not adversely affect the Big Spring Spinedace or its Critical Habitat. Fences have been constructed to separate the aforementioned allotments and should minimize detrimental effects.
The occurrence of non-native fishes, including Rainbow Trout, Largemouth Bass, and White Crappie, in Condor Canyon has been reported (Allan 1985). These species could prey on Big Spring Spinedace as well as compete with them for food and space. Mosquitofish (Gambusia affinis) have been implicated as a factor contributing to the extirpation of Big Spring Spinedace from its type locality at Big Spring (Miller and Hubbs 1960); however, it is unknown if they have ever occurred in Condor Canyon. Introduced crayfish are also abundant in Condor Canyon. Generally crayfishes are omnivorous although they commonly feed on snails and small fishes (Pennak 1989). They eat all kinds of succulent aquatic vegetation and could potentially impact the watercress and other aquatic vegetation, although Langhorst (pers. obs.) did not observe any evidence of this in Condor Canyon.
There is also a threat from human activity within Condor Canyon. Since abandonment of the Union Pacific Railroad and subsequent track removal in 1984, public use has increased. Threats include stream degradation resulting from off-road vehicles, garbage dumping, and wood cutting. Increased access may also result in introduction of additional non-native species. Effects from human activity could be minimized by closure of the existing road on the former railroad bed.
|Conservation Actions:||This species would benefit from habitat restoration and improved habitat protection and management, including control of non-native species.|
|Citation:||NatureServe. 2014. Lepidomeda mollispinis. The IUCN Red List of Threatened Species 2014: e.T62202A70621612.Downloaded on 16 July 2018.|
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