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largely recapture data because the majority of fish recaptured were collected in a single area (Escalante). Telemetry data through three spawning events showed at least three of the six individuals monitored were found on multiple spawning sites. One individual was initially caught (expressing milt) at the Yampa River site, but over the next two years was located only at the Escalante site. In addition to individuals found on different spawning sites among years, one fish (40.140) was located on two spawning sites during the same year. Based on multiple presence of fish on different spawning sites, it is probable that some fish spawn at different locations. Thus, a single spawning population of razorback sucker probably exists in the middle Green River with most individuals spawning at a primary spawning site and additional spawning occurring at alternate spawning sites. Adult razorback sucker monitored with telemetry remained in main-channel habitat during the baseflow period. At this time, fish occupied primarily runs and eddies. Tyus (1987) observed that razorback sucker occupied sites behind mid- channel sand bars during the summer in water that ranged from 0.6 to 3.4 m deep. Razorback sucker below Split Mountain Canyon occupied similar habitat. However, most fish at some time during the summer of 1993 moved into Split Mountain Canyon and occupied deeper runs and eddies. The habitat-use data collected from subadult fish in Old Charley Wash were inconclusive and provided little insight into the habitat needs of subadult fish. CHAPTER 2: Determination of growth and survival of larval and juvenile razorback sucker in wetlands relative to mainchannel habitat METHODS A pilot study comparing growth and survival of juvenile razorback sucker between backwater and wetland habitat was conducted using cage enclosures in 1991. Additional experiments in 1993 were conducted to evaluate growth and survival of larval and juvenile razorback sucker in the presence and absence of red shiner Cyprinella lutrensis. The design of the pilot study to compare growth and survival of juvenile razorback sucker among habitat types included stocking groups of 20 fish (80 to 180 mm total length) into separate 1.1 m diameter circular cages with 6 mm wire mesh siding and 13 mm wire mesh floor. Two cages were secured to the bottom substrate with stakes in each of three wetland and three main-channel backwater habitats. In addition, fish were held in two hatchery troughs and maintained on a maintenance diet (Le., 5% of body weight/d) of commercial trout feed at the Ouray Native Fish Facility on the ONWR. The three wetlands included Old Charley Wash (RK 402), Leota Bottom (L7, RK 418), and Sheppard Bottom (S3, RK 409). All wetlands were located on the ONWR. The three riverine backwater sites were located at RK 394 (West Branch, below the ONWR), RK 412 (within the ONWR), and RK 451 (above the ONWR). Prior to the trials, all fish were measured for individual total length and weight, and then PIT 23