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upstream movement for the remainder of the tracking period. Habitat use was analyzed for fish that were confirmed alive or we confidently believed that were alive during radio contacts. Fish were confirmed alive if the radio signal was located upstream from the previous contact. Furthermore, habitat-use data were not used once a radio signal remained at the same location for the remainder of the study. Consequently, habitat-use data for fish that could not be verified alive or the radio signal did not move for several months were not used. These data may represent abnormal behavior of stressed or dying fish. For this reason, the total number of habitat observations were less than the radio contact observations in both rivers because we could not reliably determine if fish were alive or behaving normally during some radio contacts. Habitat classifications defined by the Interagency Standardized Monitoring Program were used to describe habitats occupied by radiotagged fish. RESULTS AND DISCUSSION Forty-one razorback sucker were implanted with radio transmitters 5 April 1994 and stocked prior to runoff (Appendix A; Tables A.1. and A.2.). Radiotagged adult razorback sucker were stocked in historical habitat at three sites between Rifle and Debeque (RM's 228.8, 220.9, and 211.1) and at three sites between Hartland Dam and the Roubideau Creek (RM's 59.4, 53.5, and 51.5). Fish were stocked into backwaters because it was believed that riverine habitats with no or low velocities would provide stocked fish the best opportunity to acclimate to the higher river velocities. Two sites, a backwater downstream of Parachute (RM 220.9) and an overflow side channel upstream of Debeque (RM 211.1) in the Upper Colorado River, were selected because adult razorback sucker had been captured there previously (Valdez et al. 1982: Personal communication, George Kidd). Twenty razorback sucker (mean TL and weight: 502 mm and 1,194 g: range TL and weight: 451-534 mm and 966-1,498 g) were stocked in the Upper Colorado River 6 April. Seven fish each were stocked at RM's 228.8 and 220.9 and six were stocked at RM 211.1 (Figure 1). Twenty-one fish (mean TL and weight: 494 mm and 1,227 g: range TL and weight: 455-536 mm and 984-1,476 g) were stocked in the Gunnison River 7 April. Seven fish each were stocked at RM's 59.4, 53.5, and 51.5 (Figure 1). Another four radiotagged razorback sucker (mean TL and weight: 480 mm and 1,154 g; range TL and weight: 459-526 mm and 1,000-1,460 g) were stocked at RM 53.6 in the Gunnison River 13 September 1995. These four fish had been held in ponds at Horsethief SWA for observation--one since April 1994 and three since March 1995. Movement, Dispersal Patterns, and Survivorship Upper Colorado River A total of 96 individual radio contacts was made periodically with 19 fish. Between 13 April 1994 and 11 August 1995, radio contact was made with fish on 38 different days. Radio contact ranged from 10 to 491 days (Table 1). Five fish 5