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UPPER COLORADO RIVER <br /> To monitor recovery of the Colorado pikeminnow,the Recovery Program conducts <br /> multiple-pass, capture-recapture sampling on two stretches of the upper Colorado River which <br /> are roughly above and below Westwater Canyon (Osmundson and White 2009). In their most <br /> recent summary of those data(Osmundson and White 2013, in draft)the principal investigators <br /> conclude that during the 19-year study period [1992-2010], the population remained <br /> self-sustaining. The current downlisting demographic criteria for Colorado pikeminnow <br /> (USFWS 2002b) in the Upper Colorado River Subbasin is a self-sustaining population of at least <br /> 700 adults maintained over a 5-year period, with a trend in adult point estimates that does not <br /> decline significantly. Secondarily,recruitment of age-6 (400-449 mm TL), naturally produced <br /> fish must equal or exceed mean adult annual mortality (estimated to be about 20 percent). The <br /> average of all adult estimates (1992—2010) is 644. The average of the five most recent annual <br /> adult population estimates is 658. Osmundson and White (2014) determined that recruitment <br /> rates were less than annual adult mortality in six years and exceeded adult mortality in the other <br /> six years when sampling occurred. The estimated net gain for the 12 years studied was 32 fish> <br /> 450 mm TL. Whereas the Colorado River population may meet the trend or `self-sustainability' <br /> criterion, it has not met the abundance criteria of`at least 700 adults' during the most recent five <br /> year period. Updated graphs of Colorado pikeminnow abundance in the Colorado River are <br /> shown in Figure 1 (adults) and Figure 2 (subadults) (Service 2015a). <br /> Upper Colorado River Subbasin: Colorado pikeminnow adults <br /> 1400 <br /> 1200 <br /> a� <br /> E 1000 — <br /> W <br /> u 800 <br /> fCt T <br /> 600 <br /> Q 400 <br /> 3 <br /> Q 200 <br /> 0 <br /> 1991 1993 1995 1997 1999 2001 2003 2005 2007 2009 2011 2013 2015 <br /> Year <br /> Figure 1. Adult Colorado pikeminnow population abundance estimates for the Colorado River <br /> (Osmundson and Burnham 1998; Osmundson and White 2009; 2014). Error bars represent the <br /> 95 percent confidence intervals. The 2013 and 2014 data are preliminary and represented by <br /> hollow data points. <br /> 8 <br />