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. . . Hamman (1982a, 1982b) used acetone-dried CP injected intraperitoneally at a dose of 4 mg/kg of body weight to induce ovulation of wild humpback chub (Table 2.4a). Seventeen fish produced an average of 2,523 eggs per female. Highest hatching success (84%) of humpback chub was with eggs held at 19 - 200C, while warmer temperatures of 21 - 220C yielded slightly lower success of 79%. Incubation temperatures of 16 - 170C resulted in 62% hatching success while only 12% of the eggs hatched that were incubated at 12 - 130C (Table 2.4b). Hatching time at 19 -20oC was 115 - 160 hours. Hamman (1982b) also held swim-up fry in concrete troughs at 21 - 220C, 19 - 20oC, 16 _170C, and 12 - l3OC, and found survival rates of 99, 95, 91, and 15%, respectively (Table 2.4c). Fry held at 21 - 220C were 36.9 - 47.5 mm long in 56 days (Table 2.4d). No information was available for humpback chub held as Phase II (Table 2.4e). In the only effort to procure eggs from humpback chub in the wild, Valdez and Valdes- Gonzales (1991) successfully stripped and fertilized 18,000 eggs from three females following multiple injections of acetone-dried CPo The three fish yielded 4,000, 4,000, and 10,000 eggs. These fish were among 18 adults captured in Black Rocks, Colorado River, Colorado on June 2, 1980, held in live pens in the river for 5 days, and released. The river temperature at the time of capture was 11.50C. The eggs were transferred to Willow Beach NFH. Bonytail Chub Little variation in technique has been used in culturing bonytail chub. A summary of past culture efforts for this species is presented in Table 2.5. All brood stock in existence are from Lake Mohave, Arizona, in the Lower Colorado River Basin. Although some wild fish have recently been captured in the upper basin, none have been transferred to hatchery facilities. 2.2 - 4