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Bonytail Chub Of the big, native Colorado River fishes, bonytail chub (Gila elegans) have come the closest to extinction. Apparently only a few old fish remain in two reservoirs in the lower basin (Minckley, 1973) and only an occasional collection has been made in the Gray Canyon area of the Green River in the upper basin (Tyus et.al., 1982). Extensive collecting efforts to obtain bonytail chub for culture purposes during the past five years has produced only 18 fish; five of these fish remain alive (two females and three males). Hamman (1982) successfully spawned bonytail chub at Willow Beach NFH in 1981. Fry obtained from this spawning were reared at Dexter NFH and now constitute a captive held broodstock. Spawning trials on a few of these two-year-old fish were initiated in 1983 and the results are summarized below. Like the razorback sucker and Colorado squawfish, bonytail chub are long-lived. Recent age determinations made by Bruce Taubert (personal communicaton) of two Lake Mohave specimens placed their age at 40 and 42 years. Twenty-four female bonytail were spawned over a four week period during May utilizing CP to stimulate egg ovulation. Spawning and hatching techniques utilized were the same as those reported for Colorado squawfish except that jars were not tested. Good quality eggs were obtained throughout the spawning trial. The fish ranged from 0.1 to 0.5 pounds in weight with a mean weight of .28 pounds. Fecundity ranged from 1,015 to 10,384; mean fecundity was 4,677. Average number of eggs per pound of body weight varied from 5,075 to 29,930 with a mean of 17,280. A total of 119,764 eggs were taken with a mean viability of 67.5%. Eggs were hatched in Heath incubators at 700F. Fry were distributed to the Arizona Game and Fish Department and the California Department of Fish and Game; no fingerlings were reared at Dexter.