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capture rates are similar river-wide and across years. The result was size-dependent probability <br />of capture relationships that had similar shapes but whose magnitude varied across occasions, <br />reaches, and years. <br />Based on trends in point estimates over time, abundance of adult Colorado pikeminnow <br />showed an apparent decline in every river reach of the Green River Basin over the duration of the <br />study (Tables 3-7, Figs. 3-7). Abundance of adult Colorado pikeminnow in the Yampa River <br />reach was the lowest observed among the five study reaches. Point estimates declined 29% from <br />about 317 (SE = 105) fish in 2000 to about 224 (SE = 75) fish in 2003. Overlapping confidence <br />limits among pairs of point estimates did not suggest that any were statistically significantly <br />different. Regression analysis of loge abundance as a function of time (N = 4) showed a negative <br />relationship (loge abundance = 243.03 - 0.1186*year, r-2 = 0. 85, p = 0.079). Except for 2001 (CV <br />= 15%), Yampa River estimates had relatively low precision (wide confidence intervals, CV's of <br />31 to 34%) owing to the low number of fish captured and recaptured. This was especially true in <br />2002 and 2003, when no recaptures were made of fish captured and released in each respective <br />year. Numbers of unique animals captured in 2002 and 2003 were only a third to a fourth of <br />those captured in 2000 and 2001 despite approximately equivalent sampling effort among years <br />Probabilities of capture were also very low in 2002 and 2003 (Table 8). No estimate of Colorado <br />pikeminnow recruit abundance was available in any year for the Yampa River, because only a <br />single recruit-sized fish was captured (year 2000). <br />Abundance of adult Colorado pikeminnow in the White River was higher than that <br />observed in the Yampa River from 2000 to 2003 but estimates declined more dramatically over <br />the study period. Estimated numbers of adult fish declined steadily from 1,100 (SE = 220) in <br />2000, to 746 (SE = 98) in 2001, to 643 (SE = 94) in 2002, and finally to 407 (SE = 68) in 2003, a <br />26