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Microhabitat Selection of the Owens Tui Chub, Gila bicolor <br />snyderi, in the Hot Creek Headsprings, Mono County, California. <br />by <br />Dennis McEwan <br />California Department of Fish and Game <br />4001 N. Wilson Way <br />Stockton, Ca. 95205 <br />Abstract <br />Microhabitat selection of the Owens tui chub, an endangered <br />cyprinid inhabiting the Hot Creek headsprings, was investigated <br />from June 1986 to February 1988. The purpose of the study was to <br />elucidate the relationship of the chub and aquatic vegetation for <br />management (recovery) purposes and to identify potential impacts <br />from operations of the Hot Creek Fish Hatchery which diverts <br />water from the headsprings. Test specimens were placed in an <br />artificial stream chamber containing two microhabitat types: an <br />'open' cell with no cover and a 'vegetation' cell containing <br />ample amounts of vegetative cover. After an acclimation period <br />the number of individuals in each microhabitat type was recorded. <br />Sixty-four observations were made over different diel and <br />seasonal periods. Chi-square analysis showed that the chubs <br />overwhelmingly selected for the vegetation cell. Distribution <br />experiments using minnow traps support these findings. The <br />chubs' close affinity, for aquatic vegetation is due mainly to <br />four factors: spawning, water velocity displacement, predator <br />avoidance, and feeding behavior. <br />Abstracto <br />11