Spawning and Culture of Humpback Chub

During 1981, humpback chub (Gila cypha) were spawned and cultured at Willow Beach (Arizona) National Fish Hatchery. This species is listed as endangered by the U.S. Fish and Wildlife Service. Seventeen wild females ovulated after injection with 4 mg acetone-dried carp pituitary per kilogram of body weight. Eight females were stripped manually, whereas the remaining nine injected females spawned naturally in a trout raceway. Mean fecundity of eight females was 2,523. Incubation periods ranged from 102 to 146 h at water temperatures of 21-22°C, 115 to 160 h at 19-20°C, 167 to 266 h at 16-17°C, and 340 to 475 h at 12-13°C. Survival of eggs was 79% at 21-22°C, 84% at 19-20°C, 62% at 16-17°C, and 12% at 12-13°C. At hatching, total length and weight of fry ranged from 6.7 to 7.4 mm and 2.8 to 4.2 mg. The survival of swim-up fry was 99% at 21-22°C, 95% at 19-20°C, 91% at 16-17°C, and 15% at 12-13°C. The length of fry placed in raceways had doubled by 21 to 28 days, and fingerlings attained a range of 36.9 to 47.5 mm and 586.5 to 887.4 mg by day 56 after hatching.