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<br />~ <br /> <br />Hatchery-raised Colorado squawfish can survive in the wild, but their <br />ability to reproduce there is unknown. About 1500, 8-15 inch Colorado <br />squawfish raised at Willow Beach NFH (1974-1980) were tagged and stocked <br />in the Upper Colorado River in 1980. Fifteen of these fish have been <br />recaptured by CRFP, some as late as 3 years after stocking. These fish <br />were found in association with wild Colorado squawfish and had grown <br />well, th"us indicating adaptability to wild conditions. About 30,000 <br />fingerling (2-3 inch) Colorado squawfish from Dexter NFH were implanted <br />with coded wire tags and released into backwaters and gravel pits alon9 <br />the Upper Colorado River near Grand Junction, Colorado in October 1982. <br />Some of these fish were recovered by CRFP and Utah State University <br />(USU) personnel in July 1983. Stocked at 38-88 mm TL in October, they <br />were 11 0-120 mm TL and in good body condition when recaptured in July, <br />in spite of high runoff and much colder than average water temperatures. <br />Some hatchery-reared humpback and bony tail chubs also have been stocked <br />into the waters of the Colorado River Basin. About 7300 humpback chubs <br />from Willow Beach NFH were released into the Upper Colorado River in <br />Cataract Canyon during December 1981. No attempt has yet been made to <br />recapture any of these fish. In 1982, the FWS, Region 2 released 42,000 <br />hatchery-reared bony tail chub into Lake Mohave. <br /> <br />Several types of hatchery and laboratory facilities have been used to <br />culture Colorado River endangered fishes. At Willow Beach NFH, water <br />was held in raceways and aerated mechanically and circulated to achieve <br />a water temperature of 700F for spawning and growth. However, ammonia <br />and other waste products built-up in these raceways. Therefore, the <br />water was replaced periodically and solid wastes were removed. At the <br />University of Idaho, more than 40,000 Colorado squawfish and humpback <br />chub from Willow Beach NFH were reared for several months in a closed <br />system with a biofilter that removed metabolites from the water. Colorado <br />squawfish, humpback chub and bony tail chub have also been reared successfully <br />in flow-thru systems at Utah's Fisheries Experiment Station (FES) and <br />USU. This year, the FWS Field Research Laboratory at Jackson, Wyoming <br />received Colorado squawfish sac-fry from Dexter NFH which they have been <br />rearing successfully on brine shrimp and trout feed in flow-thru tanks <br />using 700F geothermal well water. In the last two years, Dexter NFH has <br />successfully produced Colorado River fishes in earthen ponds. Warm- <br />water ponds have also been used successfully at Hotchkiss NFH, Page <br />Springs State Fish Hatchery (SFH), Arizona and Niland SFH, California. <br /> <br />Findings <br /> <br />Fish Needs <br /> <br />T-he number of hatchery-reared Colorado River endangered fishes required <br />from hatcheries to meet the Region 6 management needs were estimated, <br />taking into account each 'goal and task described in the CPo These <br />estimates, given in the following outline are somewhat subjective, but <br />are based on previous experience with contracted studies done for CRFP, <br />1979-81. <br /> <br />5 <br />