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methods, i.e., in this study 80% of the humpback chub were captured by electro fishing and 20% by angling, whereas for the historic data 41 % were captured by electro fishing, 53% angling, and 7% trammel netting. Most adult sampling was directed toward collecting capture-recapture data for the purpose of making a population estimate. We captured, PIT tagged, and released 83 fish and recaptured 3 fish (Table 3). One recapture was tagged the previous year; the other two recaptures were tagged 12 d earlier on the previous pass. Only in 2000 were we able to recapture fish that had been captured on a previous pass the same year, a condition necessary to assume demographic closure for making a population estimate using CAPTURE. On release, all tagged fish appeared fully recovered and swam away. On two occasions, however, we recaptured fish on the same day, downstream from where they were originally caught (0.8 and 1.4 km). On recapture, these fish appeared healthy and fully recovered. Juvenile captures. Seining shallow shorelines, pools, backwaters, and eddies yielded 426 Gila from the entire length of the study area in 1998 (Figure 4). We identified 33 as humpback chub, 374 as roundtail chub, and 19 as Gila spp. The abrupt end at the downstream side was the result of ending sampling at rkm 17 (downstream range of the Yampa River humpback chub adults). Indeed, we find juvenile Gila commonly downstream through Island Park (Chris Kitcheyan, Colorado River Fish Project, Vernal, Utah, unpublished data) and less frequently in the lower, alluvial section of the Green River down to Ouray (Colorado River Fish Project, Vemal, Utah, unpublished data). All humpback chub and most (95%) roundtail chub captured by seine in 1998 were < 200 nun TL (Figure 5). Length-frequency suggest two age classes, age 1 9