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<br />VALDEZ AND MUTH
<br />
<br />and rest in pools, eddies, and deep runs (Beyers et
<br />al. 2001). Larvae and juveniles use shallow, low-ve-
<br />locity shorelines and backwaters (Haines and T yus
<br />1990; Robinson et al. 1998). Adults prefer large
<br />cool streams of20oC or less and occupy areas with
<br />moderate to fast current and rocky substrates
<br />(Banks 1964; Vanicek 1967; Holden and Stal-
<br />naker 1975b; McAda et al. 1980; Tyus et al. 1982;
<br />Sublette et al. 1990). Adults move little and tend
<br />to remain in home ranges (Vanicek 1967; Holden
<br />and Crist 1981; Cavalli 1999; Beyers et al. 2001).
<br />Spawning in the upper basin occurs in spring and
<br />early summer at water temperatures of 15.6-
<br />24.60C (Holden 1973; Sigler and Sigler 1996).
<br />Females broadcast adhesive eggs over mid-chan-
<br />nel cobble/gravel bars that incubate 7-8 d at
<br />15.6-17.70C, and emerging larvae 9-11 mm TL
<br />are transported downstream by river currents
<br />(Valdez et al. 1985). Fecundity is 5,000-20,000
<br />eggs per female (Smith 1966; McAda and Wydoski
<br />1980). Larvae and young feed primarily on diptera
<br />larvae, diatoms, and zooplankton (Maddux et al.
<br />1987; Grabowski and Hiebert 1989; Muth and
<br />Snyder 1995; Childs et al. 1998). Juveniles and
<br />adults use the cartilagenous ridge inside each lip
<br />to scrape algae, organic and inorganic debris, and
<br />small aquatic insects from rocks and boulders
<br />(Simon 1935; Banks 1964; Vanicek 1967;
<br />Maddux and Kepner 1988; Muth and Snyder
<br />1995).
<br />
<br />Mountain Sucker
<br />
<br />Mountain sucker reach a maximum size of305 mm
<br />TL (Sigler and Sigler 1996). The body is elongate
<br />with a moderately thickened caudal peduncle, and
<br />the mouth is subterminal and sucker-like with dis-
<br />tinct lateral notches. Like the bluehead sucker, it has
<br />canilagenous scraping ridges inside each lip. Moun-
<br />tain sucker is a species of special concern in Colo-
<br />rado and has no direct federal protection.
<br />Mountain sucker was once common in high
<br />elevation streams of the Colorado River system. In
<br />the upper basin, it is found in many tributaries at
<br />elevations of 1,220-3,050 m (Tyus et al. 1982). Its
<br />popularity as a forage and baitfish expanded its
<br />range, and by 1940, mountain sucker was in many
<br />reservoirs and tributaries (Sigler and Miller 1963).
<br />
<br />During 1950-1970, mountain sucker expanded its
<br />range ro drainages of the upper Green River
<br />subbasin, including Ashley Creek, White River, and
<br />Price River. Adults inhabit cool, clear tributaries
<br />where they are tolerant to occasional turbidity and
<br />are common over gravel, rubble, or boulder sub-
<br />strates. Mountain sucker does not occur naturally
<br />in lakes but survives in lakes if introduced. Adults in
<br />winter and early spring are found adjacent to pools
<br />in velocities of 0.5 m/s and depths of 1.5 m (Sigler
<br />and Sigler 1987). Fecundity is 2,100-4,000 eggs
<br />per female, and spawning is in late spring and early
<br />summer when water temperatures are 17-190C
<br />(Hauser 1969). Males mature at ages 2-4 and 127-
<br />145 mm TL; and females mature at ages 3-5 and
<br />122-130 mm TL. The diet of young and adults is
<br />mostly algae and diatoms scraped from rock sur-
<br />faces; and diptera, higher plants, animals, and de-
<br />bris (Sigler and Sigler 1996).
<br />
<br />Speckled Dace
<br />
<br />Speckled dace is a small fish with an elongate body,
<br />rounded fins, and a strong, thick caudal peduncle.
<br />The mouth is subterminal, otten with a small bar-
<br />bel at the end of each maxillary. Adults rarely ex-
<br />ceed 75 mm TL. The species has no special state or
<br />federal protection. Its status in the upper basin is
<br />not well known, but genetic clades unique to spe-
<br />cific drainages may be threatened by habitat alter-
<br />ations, stream impoundment and dewatering, de-
<br />graded water quality, and nonnative fishes (Oakey
<br />et al. 2004).
<br />Speckled dace is widespread in the upper ba-
<br />sin, except where habitat has been eliminated or
<br />degraded. The species has been extirpated locally
<br />by predation and competition from nonnative spe-
<br />cies, although its tolerance to low flows, high tem-
<br />peratures, and low oxygen enables it to persist
<br />where other species might perish. It is found in a
<br />variety of habitats and tolerates a wide range of
<br />water conditions, including cool mountain streams,
<br />medium and large rivers, small impoundments,
<br />small isolated desert springs, and intermittent
<br />streams.
<br />Speckled dace mature at 2 years of age, and
<br />fecundity is 174-514 eggs per female (Sigler and
<br />Sigler 1987). Spawning in the upper basin occurs
<br />
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