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<br />Table 4-4. Dates, flow, time spent at each passage site (Min = minutes) by four Colorado <br />pikeminnow implanted with transmitters as they migrated downstream and upstream of the <br />Yampa River spawning site. <br /> Downstrewn Upstream <br />Sile Freq. Date Flow Min Dale Flow Min <br /> - <br />Cross Mountain 856 . 7/l/97 3,590 17 7131/97 820 60 <br />Cross Mountain 513 7/11/97 1,664 54 8/2/97 874 141 <br />Cross Mountain 804 7/12/97 1,548 54 8/5/97 602 209 <br />Cross Mountain 502 7117/97 1,072 62 7/31/97 820 45 <br /> Mean 46.8 113.8 <br />Mayben 856 Not logged 8/2/97 874 213 <br />Mayben 804 7n 197 2,269 17 8/12/97 1,366 543 <br />Mayben 513 7/8/97 2,193 9 8/5/97 602 186 <br />Mayben 502 7/16/97 1,161 980 8/2/97 874 48 <br /> Mean 335.3 247.5 <br /> <br />Disc",.inn: Unusually high summer base flows and the observation of only four fish limited the <br />direct informatinn gained by this study regarding potential barriers that would impede upstream <br />movement of posts pawned, migratory Colorado pikeminnow. Despite these limitations, this <br />study provided information on travel times of pikeminnow through the Maybell Diversion site, <br />and allowed estimation of the time spent in the spawning area as wel1 as upstream and <br />downstream migratory speeds of individual fish. Movement of fish in this study showed the <br />same relationship of migratory movement to flow patterns as defined by Tyus (1990) and Tyus <br />and Karp (1991) with fish moving to the spawning area on the descending limb of the <br />hydrograph and leaving prior to the onset of base flows. However, using estimates of spawning <br />derived from larval fish presence, Bestgen et aI. (1997) determined the onset of spawning of <br />Colorado pikeminnow over a seven year period (1990-1996) occurred within a 14 day period <br />between June 13 and July I, irregardless of flows. The only environmental factor correlated with <br />the onset of spawning by Bestgen et aI. (1997) was degree days. Although initiation of spawning <br />occurred on similar dates, spawning occurred for a longer duration during higher flow years. By <br />estimating the dates of spawning and travel time of migratory Colorado pikeminnow, it is <br />possible to determine flows that would occur when fish passed through suspected barriers, i.e., <br />Cross Mountain Canyon and the Maybel11rrigation Diversion. Comparing U.S.~.S. gage <br />records from the Maybel1 gage with estimated spawning dates (from Bestgen et aI. 1997) <br />between 1990 and 1996, postspawning migration of Colorado pikeminnow through Cross <br />Mountain of Colorado pikeminnow through Cross Mountain or the Maybel1 Diversion was <br />problematic only in 1994. During the low baseflow years of 1990 through 1992, sufficient flows <br /> <br />CAP-9c-4 <br />