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<br />1 <br />t <br /> <br /> <br />1 <br />1 <br /> <br /> <br /> <br />1 <br /> <br /> <br /> <br />1 <br />i~ <br />Total U,.pper Basin Population <br />Using the tag data base (McAada, pers. commun. ), we conducted amark-recapture <br />estimate of the number of Colorado squawtish adults remaining for the past 3 years in <br />the UCRB: -All Colorado squawfish collected since 1991 have been implanted and <br />checked for PIT tags during Interagency Standardized Monitoring Program (ISMP) <br />sampling. All the tagging data was complied by McAda. We used the Jolly-Seber <br />mark-recapture model to estimate age 4 and greater Colorado squawfish in the entire <br />Upper Basin. This model allows for immigration and death. The specific model that <br />was used in this population estimation assumed a constant survival rate and a time- <br />specific capture probability. <br />The data was compiled and the Jolly program calculated abundances and survivorship <br />for 1992, 1993, and 1994 (Table 2). The estimates suggest that slightly over 3000 <br />Colorado squawfish remain in the UCRB. Osmundson and Burnham (1996) estimate <br />approximately 600 Colorado squawfish remain in the Colorado River. We therefore <br />used an estimate of 2400 Colorado squawfish in the Green River with 1400 returning to <br />the Yampa River and 1000 returning to the middle Green River (RK 220-260) to spawn. <br />The distribution of 1400 fish for the Yampa and 1000 fish for the middle Green was <br />mostly arbitrary, though information from Nesler (1992) and the Colorado squawfish <br />workshop participants was incorporated into the decision. Given the present use of the <br />model; to estimat the number of adults required to maintain minimum population sizes, <br />17 <br />n <br />