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COLORADO SQUAWFlSH MODEL <br />The Colorado squawfish model includes three subpopulations occurring in the middle <br />Green River site (from the Yampa to Three Fords Rapid-sections 1-6 ,the lower Green <br />River site (from Three Fords Rapid to the confluence-sections 7-9), and the Colorado <br />River site (sections 10-14). Three spawning areas define each subpopuiation with all <br />adults within each subpopulation spawning at the one spawning area per site (the first <br />river section in the site). Descriptions of how parameters were estimated is given in the <br />next section. <br />PARAMETER ESTIMATION <br />Sex Ratio <br />We found only two estimates for Colorado squawFish sex ratios (Hawkins 1992, <br />Seethaler 1978). Seethaler's estimate was based on direct observation of reproductive <br />tissues following dissection and suggest that only 20°~ of the spawning adults are <br />female. Hawkins estimated sex ratio from the tagging database where records of <br />observations of gametes identified the sex of the fish. This method may have more <br />bias, as males release gametes for longer periods of time, however, the estimate of sex <br />ratio was similar to Seethaler's estimate. In addition, Williamson (personal <br />communication) suggests that 1/6 of spawning Sacramento squawfish were females <br />25 <br />