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<br />'..J <br /> <br />-) <br /> <br />the fall and spring and thus enabling the use of existing catch per unit effort data <br />for estimating overwinter survival, and 4) providing overwinter survival estimates <br />based on mark and recapture methods, <br /> <br />III, Study Goals, Objectives, End Products: <br /> <br />The goal of this study assesses the effects of winter/spring flows on spring movement, <br />dispersal and overwinter survival of age-O Colorado squawfish in the Green River, Utah. <br />Specific objectives include: . <br /> <br />1. Determine extent of downstream movement of young Colorado squawfish <br />between I November and I April, <br /> <br />2, Determine the effect of timing and magnitude of spring flows on dispersal <br />of age-I Colorado squawfish, <br /> <br />3, Estimate the seining catchability coefficients (i,e" the probability one <br />unit of effort will catch a given fish) for autumn and spring sampling, <br />(This information will be used to determine a correction factor that can <br />be applied to existing catch per unit effort data to calculate overwinter <br />survival,) <br /> <br />4, Estimate overwinter survival using mark and recapture methods, <br /> <br />The end product will be a report that predicts overwinter movement and survival <br />resulting from various fall, winter, and spring flow regimes, <br /> <br />IV, Study area: <br /> <br />The study area will be the upper (rmi 320 - 215 and lower (rmi 120 - 0) Green River, <br />Utah, <br /> <br />V. Study methods/approach: <br /> <br />The approach of this study is to conduct mark and recapture estimates of young Colorado <br />squawfish in 20 mile river reaches of the upper and lower river in the autumn (15 <br />October) and again in the spring (15 April). The fish captured in five mile subreaches <br />will receive unique batch marks (latex marks developed in FY 93 study), Fish movement <br />between autumn and spring (prior to spring runoff) will be assessed by recaptures <br />during spring population estimates, If immigration and emigration is small, then we <br />can calculate overwinter survival using the population estimates, Dispersal of age-I <br />Colorado squawfish by spring runoff will be assessed by comparing the catch over time <br />of marked fish passing by three downstream sampling locations between 15 April and 15 <br />July at lower and upper river sites, The specific description of tasks includes: <br /> <br />1. Make a population estimate in 20 mile reach of upper (rmi 320- 215) and lower <br />(rmi 120-0) Green River in early October, <br /> <br />a, Mark approxi matel y 600 "underyearl i ng Colorado squawfi sh wi th i n each 20 <br />mile study reach, Give a unique batch mark for fish captured in two mile <br />subreaches (total of 10 different batch marks), <br /> <br />2 <br />