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Colorado River had overwintered and persisted in the system for more than six months. Most of the long-term recaptures in the Colorado River occurred in 2001. In the Green River, a total of 523 or 0.4% of the stocked bonytail were recaptured between 1999 and 2002. Of the Green River recaptures, 59 fish had overwintered and persisted in the system for more than six months. As in the Colorado River, the majority (31) of all long-term recaptures in the Green River occurred in 2001. Several factors potentially affecting survivorship of stocked bonytail were examined including location of stocking, size at stocking, and the time of year released. The bonytail catch rates on the Green River for each monitoring method were lower than those on the Colorado River. This would suggest an overall lower survival rate of individuals stocked in the Green River. A lack of fish stocked at sizes greater than 150 mm made assessment of size to survivorship relationships difficult. For example, when comparing total length at stocking to catch rates, a positive relationship (R2 = 0.85) was observed on the Colorado River, while no relationship (R2 = 0.08) was found on the Green River. The strength of the relationship found on the Colorado River was based on high return rates for one small stocking of 104 adult fish (mean TL=316.2 mm) in 1998. When this cohort is removed from analysis, no relationship (R2 = 0.01) is observed. The increase in return rate observed for the cohort of large bonytail released in 1998 was consistent with the results reported during razorback reintroduction monitoring in the upper Colorado and Gunnison rivers. Spring stocked bonytail may experience better overwinter survival. Although no overall difference was observed between short-term returns for fall and spring stockings, growth rates of small bonytail stocked in the fall showed, on average, no change in total length before the onset of their first winter. This could indicate too short of an acclimation period prior to overwintering. Overall, juvenile bonytail were found most frequently (55%) in habitats associated with flooded tributaries. Bonytail found in flooded tributary habitats were generally small (mean TL 95 mm). There was also an overall trend for bonytail captured in flowing habitats, such as runs, riffies, eddies, and shorelines, to be larger than those found in backwaters and flooded tributaries. For the 291 other Gila species captures recorded in the Colorado and Green rivers, the majority (600.10) were found in flowing habitats such as shorelines, runs, riffles, and eddies. As was seen with bonytail, other Gila found in flooded tributary and backwater habitats were generally smaller (mean TL 82 mm), than those found in flowing habitats (mean TL 221 mm). This indicates that flooded tributaries and backwaters are likely an important rearing habitat for all juvenile Gila species in these reaches. Longitudinal overlap between bonytail and other Gila species was relatively low in the Colorado and Green rivers. In the Colorado River, the vast majority of other Gila species were centered near the Dolores River. In the Green River, longitudinal overlap was higher. However, the largest concentrations of other Gila species were found above the release site in Gray Canyon and in the area within 20 river miles below the release site at river mile (RM)120. Over 98% of all bonytail were captured downstream of the release sites on both the Green and Colorado rivers. On the Green River, for all years combined, 85% of all bonytail were captured Vlll