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ponds (including those under construction) vary from 0.1 to 1.8 surface acres and comprise a total of 17 acres. The stream is a 150 foot flow-through system constructed to provide a lotic habitat to experiment with stream-type fishes. Wastewater from all fish culture operations collects in sumps on the station that are isolated from all other surface waters in the area. FISH CULTURE EFFORTS Razorback Sucker The razorback sucker (Xyrauchen texanus), one of the largest catostomids native to western waters, continues to decline in the Colorado River system. Adult razorbacks attain lengths up to three feet and weights up to 12 pounds (Minckley, 1973). Recent collections in both the upper and lower basins of the Colorado River have not produced any young fish. Documented reproductive activity occurs in Lake Mohave in the lower basin but there is no evidence of any recruitment to the aging population of adult fish. Utilizing otoliths, Bruce Taubert, Arizona Game and Fish Depart- ment (personal communication), recently showed razorback suckers from Lake Mohave to be between 30 and 35 years old. The precarious status of the razorback sucker prompted negotiation of a coopera- tive agreement between the State of Arizona and the U.S. Fish and Wildlife Service that called for the Service to stock 100,000 fingerling razorbacks annually into Arizona waters for ten years. Finalized in May 1981, this arrangement was pursued in lieu of -" listing the species (Johnson, in press). Development of cultural ,,techniques for razorback suckers, initiated in 1981,'was fairly well refined by 1983. A detailed account of the 1981 and 1982 spawning and hatching trials is reported by Inslee (in press). A brief summary of all three years work is presented here. Until recently, sexual maturation of razorback suckers has