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A total of 276,200 fry were stocked in four hatchery production ponds to rear fingerling razorbacks. Of these, 264,896 were harvested as 1.5" fingerlings for a 95.9% return. A total of 150,051 1.5" fingerlings were restocked and 140,633 3" fingerlings harvested for a 93.7% return. Two production ponds were restocked with a total of 52,930 3" fingerlings and 50,905 5" fingerlings harvested for a 96.2% return. Total survival of razorbacks in culture ponds from fry to 5" fingerling was 95% in 1985. A total of 336 four and five-year-old domestic broodfish plus a few remaining wild males are presently being utilized in the razorback sucker production program. Colorado squawfish Similar to razorback sucker, Colorado squawfish numbers have declined dramatically throughout their historic range in the Colorado River system. They are extinct in the lower basin (Minckley 1973) and only remnant populations survive in the upper basin (Tyus et al. 1982). North America's largest cyprinid, Colorado squawfish historically attained lengths up to six feet and weights of nearly 100 pounds (Miller 1961). All available data suggest that squawfish are slow growing and Long lived. Nine-year-old hatchery-reared squawfish at Dexter averaged only 20 inches and three pounds in 1983. Considering that some razorback suckers live 40 to 50 years, it is easy to speculate that a six foot, 100 pound Colorado squawfish could be 60 or more years of age. Hatchery-reared Colorado squawfish become sexually mature in their sixth year (Hamman 1981b). Colorado squawfish housed at Dexter NFH spawn in late May or early June as the water temperature nears 70° F. Altho~igh some females ripen slightly ahead of others, all muse-be spawned within a one to two-week period once they have ripened or good eggs cannot be obtained. Eggs force-ovulated prior to, or taken after the spawning peak have low viability. This requires close monitoring of female broodfish to ensure procurement of viable eggs. Female Colorado squawfish are injected with carp pituitary (CP) to induce ovulation of maturated eggs. Hamman (1981b) determined that two mg CP per pound of body weight injected intraperitoneally was the appropriate hormone, dosage and method of in is^t? on for female Colorado squawfish. Male Colorado squawfish normally :;tom; pipe and fluid but receive intramuscular injections of CG at 150 IU per pound of body weight if fluidity decreases. Colorado squawfish are spawned utilizing the wet method as described for razorback suckers. Eggs are "clayed", rinsed, water hardened, enumerated and incubated in Heath trays and jars. At 70° F, Colorado squawfish eggs also hatch between 96 and 144 hours -38-