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release of wild fish and release of hatchery fish would enhance the ability of the Recovery <br />Program to understand the contribution of different groups of hatchery fish to the Green River <br />population. <br />Length--ff-equency data.- Length-frequency histograms offish captured since 1980 were <br />1 <br />plotted to determine if size offish changed over time. Similar to Modde et al. (1996), we <br />combined 2 to 4 yeazs of data into single histograms in order to increase sample size, but we only <br />used fish size at first capture. Because we were particularly interested in detecting changes in <br />length frequencies after fish stocking began in 1996, we plotted 1996 and 1997 data together and <br />1998 and 1999 data together. We also plotted mean length of razorback suckers captured over all <br />sampling yeazs to determine if changes in length were occurring. Changes in lengths of <br />recaptured fish were also plotted as a function of time between first and last recapture intervals. <br />Abundance estimates.-Similar to Modde et al. (1996), we estimated abundance of <br />1 <br /> <br /> <br /> <br /> <br /> <br /> <br />razorback suckers in the Green River. Because the data-collection period spanned 20 years <br />(1980-1999) and because mortality and recruitment were likely occurring, this population was <br />most correctly classified as an open population. However, data collected in this study were too <br />spazse to obtain abundance estimates for open populations using the usual Cormack-Jolly-Seber <br />(CJS) methods (Pollock et al. 1990). Therefore, we used capture data from pairs of sequential <br />years to estimate an index of abundance of razorback suckers using aLincoln-Petersen estimator <br />in program CAPTURE (White et al. 1982). We used captures and recaptures in years i and i + 1 <br />and recaptures in yeaz i + 1 to compute estimates for the yeaz i + 1 as follows: <br />n n;•n;+t <br />N.+~ - , <br />mr, t +~ <br />8 <br />