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5. Downstream transport of larvae from spawning areas has been postulated by Haynes and Muth (1984), Haynes et al. (1984) and Tyus and McAda (1984). Larval drift is evidenced by the collections of larval Colorado squawfish in drift nets, and explains, the high-density of larvae in reaches'of the river that apparently have no spawning sites. Although precise distances transported are not known, it is presumed that-the extent of dispersal downstream from spawning sites is affected by river discharge. Under high discharge regimes eggs could be transported further before settling or adhering to a stable substrate - this could be a factor in survival. After hatching, the planktonic larvae may be transported further during the 72-96 h reported for them to become nektonic (Hammon 1981). The Green River discharge at Jensen, Utah during the critical spawning and nursery periods for the years 1979-80 and 1983-84 is provided in Figure 3. Also shown are the major periods of larval drift and nursery habitat util- ization. Haynes and Muth (1984) reported the highest density of drifting larvae occurred in the period August 8-10, during which roughly 80% of the larvae from the Yampa River spawning site entered the Green River. The length of time Colorado squawfish larvae drift.before seeking low-velocity nursery habitats is unknown, however, FWS fall monitoring studies of backwater and other shallow.habitats indicate a distinct preference for backwaters by September (Tyus et al. 1982). The relative abundance of larvae.by 10-mile sections' of the Green River for the years 1979-84 are shown in Figures 4-9. RECRUITMENT OF YOUNG COLORADO SQUAWFISH AS A FUNCTION OF DISCHARGE Survival of larval Colorado squawfish to the end of the growing season each year was evaluated by analyzing C/E data collected as part of the FWS fall monitoring program. C/E data for 1979-84 indicate that 1979-80 were high years, 81-82 were moderate years, and 83-84 were very low years with respect to recruitment. These data are presented in Table 2 along with August and September mean discharge at Jensen, Utah (Figure 10) and Flaming Gorge Dam. Table 2 Young-of-the-year Colorado squawfish seine collections from backwater nursery habitat and August - September discharge, Green River, 1979-84. Mean Discharge (CFS.) C/E Jensen Ut. Flaming Gorge Dam Dates N Fish 1000m"2 Aug. Sept. Aug. Sept. 1979 10/10 2095 -227.01 2338 1688 1539 1410 1980 10/7-10/8 1716 252.73 1942 1931 1618 - 1657 1981 9/14-9/15 510 125.73 1823 2465 1606 2288 1982 10/5 640 118.41 2775 3100 1776 2317 1983 10/20-11/9 '34 4.95 6463 4159 5056 3729 1984 10/9-10/28 27 7.48 5089 3061 3430 2220