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Colorado pikeminnow move seasonally (mostly in summer), fidelity of fish appears high to reaches sampled for abundance estimation because fish move back to those reaches by spring. Thus, the apparently low level of permanent emigration to unsampled reaches does not dramatically affect survival rates, which makes apparent S more closely approximate true S. A second implication of these data is for abundance estimates themselves. The mostly seasonal use of canyon reaches such as Lodore and Whirlpool Canyon, and likely lower Yampa Canyon, suggested that most Colorado pikeminnow moved to alluvial reaches by spring when abundance estimation sampling was conducted. This means that abundance estimates for Colorado pikeminnow for the reaches sampled in this study are likely representative for the entire Green River Basin because they are not biased by presence of large numbers of Colorado pikeminnow in unsampled canyon reaches. Recruitment rates.--Reduced recruitment may also be responsible, in part, for the decline of adult Colorado pikeminnow in the Green River Basin. The RIP set the definition of a recruit as a Colorado pikeminnow 400 to 449-mm TL (U. S. Fish and Wildlife Service 2002). Based on expected growth of about 43 mm/yr for Colorado pikeminnow in the 400 to 449-mm TL size- class (Osmundson et al. 1997), the average recruit-sized Colorado pikeminnow would become part of the adult population the following year. The expectation of recovery goals is that recruitment will, over time, balance mortality of adults to produce a stable adult population. In other words, the adult population is maintained when the number of adults that die in year i is balanced by the number of recruits present in year i - 1 that survive to the following year. The percentage of recruits in samples used for abundance estimation that were collected during the period 2000-2003 (4.9 to 13.3%) suggested that recruitment was not sufficient to offset the 35% 52