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42 reported to be 85/15. The specimens collected in late September could not be sexed since both male and female appear similar after spawning season. Early explorers reported that Colorado squawfish had extensive spawning migrations (Everman, 1916; Chamberlain, 1904). These migrations have been stopped in most areas by large dams and reservoirs. In sections of free flowing rivers there still appears to be limited migration. Holden and Stalnaker (1975a, 1975b) documented large numbers of squawfish moving into the Yampa River in mid to late summer and hypothesized that the movements were for reproductive purposes. McAda and Seethaler (1975) described the same phenomenon and located areas where they believed squawfish attempted to spawn. The incidence of successful squawfish reproduction in the upper Colorado River basin has declined drastically in the last 12 years. Vanicek and Kramer (1969) found successful reproduction to be the rule in the Green River below the mouth of the Yampa River, However, Holden and Stalnaker (1975b) found no juveniles or young of the year in the same area in 1970 or 1971. A continued lack of reproductive success was documented in 1974-75 by McAda and Seethaler (1975). Limited reproduction apparently is still occurring in the lower Green and Colorado Rivers in Desolation Canyon and Canyonlands National Park (Holden and Stalnaker 1975b).. Electivity curves derived for squawfish demonstrate that the adult fish occupy eddies, runs and backwaters with a predominately sand substrate (Holden, 1977). Velocity may vary from 0 to 3 ft (.9 m) per second and depth from 1 ft (.3 m) to 9 ft (3 m). Other authors have reported similar findings (Seethaler, 1978). Results from this study support these findings. One fish (Tag #USUBMIO0209) was captured in 3 ft (1 m) of water along a low sand bar bank where the bottom was a combination of sand and silt. Two other fish (Tag #USUBMIO0210 and #USUBMIO0208) were captured immediately downstream from