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injection. Females receive HCG injections every 24 hours until all eggs.have been ovulated. At the recommended dosage, they usually give a "show" of eggs at 36 hours and good spawns at 48, 60 and 72 hours; some females spawn out at 60 hours. Male razor- backs are injected with HCG at 300 IU per pound of body weight daily for two to three days. If milt production decreases, HCG injections are reinitiated to maintain production of male gametes. Utilizing the wet method, eggs from ripe females are hand- stripped into pans, milt added from two or more males and the eggs stirred gently with a feather. Razorback sucker eggs are very adhesive so the eggs are "clayed" with slurried bentonite following fertilization. The clayed eggs are poured into floating egg baskets, gently washed to remove the bentonite and allowed to water harden for 30 minutes. Following water hardening, they are enumerated gravi- metrically and placed in Heath incubator trays. Jar hatching experi- ments revealed that razorback sucker eggs are too fragile to withstand the rolling involved in this hatching technique (Inslee, in press). Marsh and Pisano (in press) conducted studies at Dexter to determine the influence of temperature on egg development and hatching success of native Colorado River fishes. They found that optimum incubation temperatures for eggs of the three species reported here was near 700F. Consequently, our well water is heated to 700F for egg incu- bation and fry development to swimup. Water flow through the Heaths. is regulated at three gpm. At 700F razorback sucker eggs begin hatching at about 96 hours and continue through 144 hours; peak hatching occurs on the fifth day at about 120 hours. Fry are held in tanks until swimup, then stocked in rearing ponds. Stocking rates for razorback sucker fry have not been finalized; we have experimented with rates ranging from 80,000 to 200,000 per surface acre. In 1983 we spawned a total of 55 wild razorback sucker females 46 of them (83.6%) successfully. The 46 fish produced 5,728,025 eggs for an average fecundity of 124,522. Egg viability at 72 hours