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<br />Craig Justice Center Pond. <br /> <br />To determine if there was tag loss between mark and recapture sample occasions that <br />could affect abundance estimation, smallmouth bass at Little Yampa Canyon were <br />double marked with a yellow Floy-tag and a partial, lower caudal-lobe clip on the first <br />sample occasion in 2007. All smallmouth bass captured on the second sample <br />occasion were examined for both marks. <br /> <br />Removal effort- We attempted to maximize the number of removal occasions each <br />year based on time and resources. To assist our planning and sampling design we <br />estimated removal rate with the formula: <br />R:; 1-(1_p)n; where <br />R:; percent of fish handled (annual rate of removal) <br />p:; capture probability (estimated from prior year) <br />n :; number of sample (removal) occasions. <br />Conversely, the number of sample occasions necessary to obtain a given level of <br />removal (removal rate) can be estimated by solving for n: <br />n:; log(1-R)/log(1-p). <br /> <br />Removal evaluation- We estimated abundance and capture probability from tag <br />recaptures of smallmouth bass with a Huggins estimator using program MARK based <br />on two to three sample passes each year (White et a1.1982; White 2008). Capture <br />probability is the probability that an individual fish will be captured on a sampling <br />occasion. We calculated catch per unit effort (CPUE) for adult smallmouth bass on <br />each sample occasion and obtained an average CPUE for all sample occasions each <br />year. To determine whether CPUE was a predictor of abundance we compared CPUE <br />with density (# adult fish / mile) which was derived from abundance point estimates <br />standardized for reach length. We determined removal effectiveness primarily by <br />examining changes in annual abundance of adult smallmouth bass (~150 mm TL) in <br />each reach starting with an initial abundance estimate in 2004 and ending with an <br /> <br />7 <br />