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<br />]68
<br />
<br />VALDEZ AND MUTH
<br />
<br />with a reddish nuptual tint. The back and belly/
<br />breast regions are moderately to heavily scaled and
<br />a nuchal hump is absent or poorly developed.
<br />Maximum size is 500 mm TL; there are 75-85
<br />scales on the lateral line that are small, thin, and
<br />slightly imbricated. Roundtail chub does not re-
<br />ceive federal protection under the ESA, but is one
<br />of three species (also flannelmouth sucker and
<br />bluehead sucker) included in a conservation agree-
<br />ment among six western states (Colorado Fish and
<br />Wildlife Council 2004).
<br />Roundtail chub was historically distributed in
<br />upper reaches of main rivers and throughout most
<br />tributaries up to about 2,300 m elevation. In the
<br />upper basin, roundtail chub was widely distributed
<br />and abundant until the early 1960s, when construc-
<br />tion of main-stem dams fragmented and inundated
<br />habitats, and altered flow regimes.
<br />Roundtail chub in the upper basin remains as
<br />15 populations in about 55% of its historic habi-
<br />tat (Bezzerides and Bestgen 2002), and is found in
<br />the Green, Colorado, and San Juan River drain-
<br />ages (Lentsch et al. 1998; Propst 1999; Bestgen
<br />and Crist 2000). It is abundant in the upper Colo-
<br />rado River from Rifle, Colorado, downstream to
<br />Moab, Utah, and in the Gunnison and Dolores
<br />rivers in Colorado (Valdez 1990;Valdez and Wil-
<br />liams 1993). It is rare in Lake Powell and occurs in
<br />small numbers in the San Juan River, Utah, and as
<br />enclaves in the Animas, La Plata and Mancos riv-
<br />ers. In the Green River, the species occurs in low
<br />to moderate numbers. Roundtail chub was once
<br />common in the Price, Duchesne, San Rafael, Dirty
<br />Devil, and Fremont rivers (McAda et al. 1980),
<br />but water depletion, nonnative fish species, and de-
<br />graded water quality have nearly eliminated it from
<br />these tributaries.
<br />Roundtail chub use rocky shorelines and sub-
<br />strate and are rare in sand-bed reaches, and young
<br />may use backwaters, if available. Adults occur at
<br />depths of up to 20 m, and typically suspend them-
<br />selves in low-velocity regions oflarge eddies adja-
<br />cent to shear zones. Adults are generally sedentary,
<br />except for spawning-related movements (Kaeding
<br />et al. 1990), although some may make extensive
<br />movements at night (Beyers et al. 2001). Maximum
<br />reported movement is 80 km in one year (Holden
<br />and Crist 1981). Spawning in the upper basin is
<br />
<br />in May and June, shortly after peak runoff. Adhe-
<br />sive eggs are broadcast over cobble and gravel at
<br />14-220C (Sigler and Miller 1963; Vanicek and
<br />Kramer 1969; Holden 1973; Kaeding et al. 1990;
<br />Karp and Tyus 1990b; Brouder et al. 2000), and
<br />hatch as 6-7 mm TL larvae in about 5 d (Muth
<br />1990). Roundtail chub typically mature in 3-5
<br />years at 150-300 mm TL, and average life span is
<br />8-10 years (Sigler and Sigler 1996; Brouder et al.
<br />2000). Fecundity of young adults is 1,000-4,300
<br />eggs per female (100-260 mm TL; Neve 1976)
<br />and about 14,160-45,120 eggs for fish 4-7 years
<br />old (Bestgen 1985). Newly emerged larvae feed on
<br />diatoms and filamentous algae (Neve 1976), and
<br />juveniles eat mainly immature midges and may-
<br />flies (Vanicek and Kramer 1969), but may also con-
<br />sume algae, caddisflies, and ostracods (Bestgen
<br />1985). Juveniles and adults consume aquatic in-
<br />sects, crustaceans, fish, plant matter, snails, ants,
<br />beetles, crickets, grasshoppers, and lizards (Koster
<br />1957; McDonald and Dotson 1960; Vanicek and
<br />Kramer 1969; Schreiber and Minckley 1981;Tyus
<br />and Minckley 1988; Karp and Tyus 1990b).
<br />
<br />Flannelmouth Sucker
<br />
<br />Flannelmouth sucker is a large, streamlined fish that
<br />commonly reaches lengths of 435-500 mm TL
<br />with a maximum of 765 mm TL and 3.5 kg in
<br />favorable habitat. Flannelmouth sucker mature at
<br />age 4-6 and may live 15 or more years (McAda
<br />and Wydoski 1980; Douglas and Marsh 1998).
<br />The caudal peduncle is thick and robust, and the
<br />mouth of adults is subterminal, enlarged, and cov-
<br />ered by large fleshy papillae. There are 90-116
<br />small, embedded scales along the lateral line.
<br />Flannelmouth sucker hybridizes with sympatric
<br />native bluehead sucker and razorback sucker
<br />(Hubbs et al. 1942; Hubbs and Miller 1953;
<br />Holden 1973; Holden and Stalnaker 1975a;
<br />Minckley 1973; McAda and Wydoski 1980;
<br />Holden and Crist 1981; Buth et al. 1987), and
<br />nonnative white sucker. Flannelmouth sucker does
<br />not currently receive federal protection under the
<br />ESA, but is one of three species included in a con-
<br />servation agreement among six western states
<br />(Colorado Fish and Wildlife Council 2004).
<br />In the upper basin, flannelmouth sucker was
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