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<br />1046 <br /> <br />be shown that Colorado squawfish return to natal <br />areas for spawning. The similarity oftheir behav- <br />ior to that of many of other fishes makes it prob- <br />able that they do so, and this could lead to repro- <br />ductive isolation and separate genetic stocks <br />(Leggett 1977; Solomon 1977; Stahl 1987). Spe- <br />cific migration routes and positive or negative <br />rheotaxis in homing orientation could be main- <br />tained in different genetic stocks by homing fidel- <br />ity (reviewed by Smith 1985). Some genetic in- <br />terchange between stocks to maintain healthy <br />levels of genetic variability could be maintained <br />by movements of fish that "strayed" from one <br />river to another, and the "strays" noted in my <br />study may be important for successful evolution <br />of the species (Baker 1982; Leggett 1984; Quinn <br />1984). Colorado squawfish movements between <br />the Green River, its tributaries, and the Colorado <br />and Dirty Devil rivers may thus be important in <br />maintaining a diversified gene pool. <br />Migration and other reproductive behavior of <br />Colorado squawfish are ostensibly attuned to a <br />variety of stimuli, including intrinsic mechanisms <br />and dependable environmental cues. A better un- <br />derstanding of these mechanisms and cues could <br />assist management and recovery efforts for this <br />endangered species. If reproducing stocks are dis- <br />tinct, as my study indicates, they may be geneti- <br />cally isolated. Population genetics of the Colorado <br />squawfish stocks in the Green River basin thus <br />deserves further attention to aid recovery efforts <br />for this species. Recovery of the Colorado squaw- <br />fish to a nonendangered status may require main- <br />tenance of separate spawning stocks and protec- <br />tion of present environmental conditions until the <br />reproductive ecology of the species is better un- <br />derstood. <br /> <br />Acknowledgments <br />This study was funded by the Bureau of Rec- <br />lamation, and Fish and Wildlife Service, U.S. De- <br />partment of the Interior. Many government em- <br />ployees assisted with the collection of data. <br />Colorado Division of Wildlife, Utah Division of <br />Wildlife Resources, Bio/West Incorporated, Col- <br />orado State University, and Bureau of Reclama- <br />tion employees furnished information. G. B. <br />Haines aided with statistical analyses. P. B. John- <br />sen provided helpful information about olfaction <br />and imprinting. C. A. Karp, J. H. Williamson, A. <br />A. Echelle, R. T. Muth, T. P. Nesler, and J. 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