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directed toward capture-recapture data for the purpose of making a population estimate. We captured, PIT tagged, and released 83 fish and recaptured 3 fish. One recapture was tagged the previous year; the other two were tagged on a previous pass the same year. We were unable to make a satisfactory population estimate (bias < 10%, CV < 0.2). Although, the study design met most of the assumptions for capture-recapture studies, too few tagged fish were captured for an unbiased and precise population estimate. A simulation study showed that an extraordinary effort would be required to achieve such an estimate. This seems infeasible considering we already were using two electrofishing rafts, and additional electrofishing would add little, as would adding additional passes. Seining shallow shorelines, pools, backwaters, and eddies yielded 426 young Gila from the entire length of the study area. We identified 33 as humpback chub. Young Gila were difficult to identify, but recent collections of age-O and age-l from Island Park sent to the Larval Fish Laboratory at Colorado State University suggested that trained personnel can make accurate field identifications. The Yampa Canyon humpback chub population appears to be persistent, and the presence of adult and young humpback chub suggests that the population is successfully recruiting. However, the population is sparse, consisting only of a few hundred to a few thousand adults in 55 km of river. An efficient monitoring plan is a critical part of any recovery program. It provides feedback on the change of status of the population, and it provides information on population response to management activities, like non-native fish control. However, an intensive capture- recapture study that results in precise population estimates for humpback chub is not feasible for Vll