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Total Upger Basin Population <br />Using the tag data base (McCada, personal communication), we conducted amark- <br />recapture estimate of the number of Colorado squawfish adults remaining for the past 3 <br />years in the upper Colorado River Basin. All CS collected since 1991 have been <br />implanted and checked for PIT tags during ISMP sampling. All the tagging data was <br />complied by McAda. We used the Jolly-Seber mark-recapture model to estimate age 4 <br />and greater CS in the entire upper basin. This model allows for immigration and <br />death. The specific model that was used in this population estimation assumed a <br />constant survival rate and atime-specific capture probability. <br />The data was complied in Method B table (Table 2) and the program called Jolly (Hines <br />1989) calculated abundances and survivorship for 1992, 1993, 1994 (Table 2). The <br />estimate suggest that slightly over 3000 CS remain in the upper Colorado River Basin. <br />Osmundson and Burnham (1996) estimate approximately 600 CS remain in the <br />Colorado River. We therefore used an estimate of 2400 CS in the Green River with <br />1400 returning to the Yampa River and 1000 returning to the middle Green River (RK <br />220-260) to spawn. <br />15 <br />