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25 observed for predicted spawning dates associated with the proposed temperature cue, some spawning also occurred on dates that preceded the flow cue. With reference to flow conditions at cessation of peak spawning activity, 1983 and 1985 comparisons demonstrate flows of 55-60 m3/s at cessation, while the 1984 comparison demonstrates a flow of 105 m3/s at cessation. Given the arbitrary designation of peak spawning activity, another variable that is not accountable for is the overall numbers of adult Colorado squawfish participating in the spawning run from year to year. The possibility exists that a significant number of the available adult squawfish participated in the peak of spawning in 1984, leaving relatively few adults to spawn afterwards even though flows were still above 55-60 m3/s. The cessation and resumption of spawning with fluctuating flows in 1985 support the conclusion that significant spawning activity ceases at flows below this threshold. Flow and temperature are key elements in the spawning requirements of Colorado squawfish. The comparison can be made, though, from seine data in Haynes et al. (1985) that the reproductive success of Colorado squawfish in 1980-1982, characterized by low flows and satisfactory thermal regimes in the Yampa, did not yield near the number of YOY fish that were sampled in 1983-1984, characterized by high flows and satisfactory thermal regimes. The difference in larval fish captured occurred despite equal or greater sampling effort in 1980-82 versus 1983-84. The degree of reproductive success for the species in 1985 under suboptimal water temperatures and a moderate flow regime tends to downplay the significance of temperature relative to the flow fluctuation cue observed in 1983 through 1985. Further analyses on flaw patterns in 1980-1982 will be conducted to evaluate the river environment during years of apparent low reproductive success. CONCLUSIONS AND RECOMMENDATIONS 1.) The relative abundance of fish species in the drift-net collections has not changed remarkably since 1983. 2.) Catches of larval Colorado squawfish in 1985 using drift-nets indicate a significant increase in reproductive success relative to 1983- 1984, but seine data and potential sampling bias in drift net collections in 1983-84 suggest reproductive success has been relatively similar. 3.) Age and growth results for larval squawfish collected in 1985 are similar to previous years. 4.) Limited variability in the length data of larval Colorado squawfish lengths collected by drift-nets over the six week period in 1985 suggest a common geographical origin for these fish, and adds support for the existence of a primary spawning area in Yampa Canyon. 5.) The length data of larval Colorado squawfish collected in drift and seine samples suggest the hypothesis that larvae 10 mm in length and smaller are transported downstream by passive drift and larger larvae proceed down river in a more active, migratory pattern to reach suitable zero-velocity nursery sites.