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aging revealed most were hatched in 1983 or 1984, the year the pond flooded; however, <br />one fish was 20+ years old (F. Pfeifer, USFWS, personal communication). It is unknown <br />whether the younger fish drifted into this newly-excavated pond as larvae during the high <br />spring flows of 1983 or 1984 or whether adults entered and spawned there producing the <br />younger cohort. Similarly, in the wetland of Old Charley Wash, eight adults were found <br />along with the 28 YOY (Modde 1996). <br />Growth <br />Rapid early-life growth of fishes promotes survival and decreases generation time <br />(maturity is reached at an earlier age), boosting the potential for population increase <br />(Kaeding and Osmundson 1988). For young razorback sucker, limited data suggests that <br />growth rate is highly variable, and is strongly influenced by environmental conditions. At <br />swim-up, larvae average 9-11 mm (Marsh 1985, Snyder and Muth 1990). At two months <br />old, two YOY captured from a backwater in the Green River were 37-39 mm long <br />(Gutermuth et al. 1994). The 28 YOY found in Old Charley Wash averaged 94 mm in late <br />October of their first year (Modde 1996). The importance of providing young razorback <br />suckers access to warm, off-channel habitats was demonstrated when 430 age-0 razorbacks <br />averaging 55 mm long were stocked into a riverside, gravel-pit pond in June 1987. By mid- <br />November they averaged 306 mm (Osmundson and Kaeding 1989). Near the end of the <br />second growing season (late September 1988), average length (405 mm) had increased by <br />99 mm. In comparison, similar size-groups (200-400 mm) stocked into riverine habitats <br />grew an average of 37 mm/yr in the San Juan River (Ryden 2000) and 62 mm/yr in the <br />Gunnison River (B. Burdick, unpublished data). At the end of their third growing season, <br />34 of the pond-reared individuals (averaging 462 mm) were sacrificed and all had <br />developing gonads indicating sexual maturity (65% males; 35% females). Growth slows <br />dramatically after razorback suckers mature, averaging 1.66 mm/yr in the middle Green <br />River (Modde et al. 1996). <br />11