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A realistic number of wild larvae that might be expected from collections during the larval monitoring effort is 1,000 annually (S. Muth, 1996, Personal Communication). Based on this estimate, 1,000 wild razorback sucker larvae will be collected with light traps as part of the razorback monitoring program. In addition, captive-reared razorback sucker from 25 paired matings will be reared in ponds at the Ouray National Fish Hatchery. The number of paired matings that are made for developing pedigreed family lots for broodstock will vary from year to year, depending upon the availability of mature wild fish that are available. During 1996, approximately 1,000 captive-reared razorback suckers from various family lots will be stocked into the Middle Green River (Table 2). The estimated survival rates and mean total length at the end of each growing season is summarized in Table 1. Based on those estimated survival rates, approximately 203 adult fish should augment the wild stock by the fall of the year 2001 (Table 2). During 1997, approximately 394 razorback suckers that are about 12-inches in mean total length will stocked into the Middle Green River to augment the wild stock (Table 3). These fish will be derived from 1,000 wild razorback sucker larvae from the Middle Green River and 3,030 captive-reared larvae from 5 pedigreed family lots will be reared in ponds at the Ouray National Fish Hatchery. About 128 razorback suckers are expected to survive from 1996 through the Year 2000 (Table 3). The number of razorback suckers that are expected to survive from the proposed stockings in 1996 and 1997 to the Years 2000 and 2001 is 331 fish (Tables 2 and 3). Razorback suckers reach sexual maturity when they are about 17 inches (- 430 mm) TL (McAda and Wydoski 1980). The fish from the 1996 and 1997 stockings should reach that size in the fall of the Year 2000 and spawn for the first time in the spring of the Year 2001. Source of Fish. The first choice would be to use wild razorback sucker larvae from natural propagation in the Middle Green River. However, the number of larvae required to increase adult razorback sucker numbers by 500 would require many years based on experience-in collecting wild larvae with light traps. Therefore, a combination of rearing wild larvae and captive-reared razorback sucker that have been exposed to synthetic chemicals will be used. Exposing developing eggs and larvae through the swimup stage is a conservative measure until the results of the ongoing chemo-reception study are available to determine if imprinting occurs in this species. If imprinting occurs in the razorback sucker, the synthetic chemical can be used to help direct the fish to suitable spawning habitat. Captive spawning will follow the Genetic Management Guidelines of 25 paired matings (Ne = 50) such that the probability of inbreeding depression will not exceed 1% (Williamson and Wydoski 1994). Genetic Identification and Characterization. When the "Genetics Management Guidelines" were written, the assumption was made that the ongoing allozyme and/or mtDNA studies would provide methods for genetically characterizing 4