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<br />. <br /> <br />. <br /> <br />. <br /> <br />existed following the last day of reproduction for the slowest postspawning migrant to reach the <br />Maybell Diversion prior to passage limiting flows (177 cfs, Modde and Smith 1995). During <br />1994 estimated Colorado pikeminnow spawning occurred until 21 July when Yampa River flow <br />at the Maybell gage was only 98 cfs. Thus, low flows were problematic for postspawning <br />migration above Cross Mountain Canyon and the Maybell Diversion even while some fish were <br />still spawning. Of interest in the low flow year of 1994 was that very few larvae were collected <br />in the Yampa River in 1994 and the majority of those were collected early in the reproductive <br />period (Bestgen et aI. 1997). <br /> <br />It is unclear whether the poor reproductive year in 1994 was the result of a lack ofreproducing <br />adults present or mass mortality of eggs deposited. It is possible that adult Colorado <br />pikeminnow left the spawning site as flows receded and that low reproduction occurring during <br />low flows could have been the product of pike minnow resident in Yampa Canyon. Travel times <br />estimated in this study indicated that individual fish only occupy the spawning area for a portion <br />of the entire spawning period. Bestgen et aI. (1997) estimated the duration of Colorado <br />pikeminnow spawning in Yampa River to range between 24 and 38 days (mean = 29.5) between <br />1990 and 1996. Similarly, Tyus (1990) estimated pikeminnow spawning to range between 31 <br />and 39 days (mean = 35.6) between 1981 and 1988. Average estimated time spent near the <br />spawning area in 1997, a high flow year, was only 15.5 days. Although it is likely that <br />individual fish do not remain in the spawning area for the duration of the spawning period, <br />factors triggering fish to leave the spawning area are unknown. In summary, evidence suggested <br />low flows in early to mid July may be detrimental to spawning, however it is unlikely low <br />baseflows are a factor in preventing passage of postspawning migrant adults. <br /> <br />VII. Recommendations: Recommendations are provided in the draft report. <br /> <br />VIII. Project Status: The project report is seven months late. <br /> <br />IX. FY 98 Budget <br /> <br />Note: The following budget includes the entire Yampa low-flow study. <br /> <br />A Funds Provided: $19K to CRFP; $19K to CDOW; $15K for panel <br />B. Funds Expended: $19K by CRFP; $19K by CDOW; panel costs? <br />C. Difference: 0 (except panel expenditures unknown) <br />D. Percent of the FY 98 work completed, and projected costs to complete: 100%,0 <br />E. Recovery Program funds spent for publication charges: $0 <br /> <br />X. Status of Data Submission (Where applicable): N/A <br /> <br />XI. <br /> <br />Signed <br /> <br />Tim Modde <br /> <br />Date 12/1 ~/9l! <br /> <br />CAP-9c-5 <br />