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1 <br />1 % was estimated for an effective population size of 50 fish. That is acceptable for maintaining the genetic <br />diversity of wild fish stocks used as founders. If significant differences in genetic diversity do not exist among <br />stocks of endangered fish species, the recommended approach is to develop 25x25 paired coatings fast from <br />local populations, then neazest neighboring populations, then from other centralized populations. When stocks <br />aze low, a minimum breeding strategy using a 5 X 5 di-allele cross will be used to develop broodstocks. A 5 <br />X 5 breeding strategy has an effective population size of 10 and estimated inbreeding rate of 5%. ]n the event <br />that 5 males and 5 females are not available, a factorial mating will be used to capture the genetic contribution <br />of the least numerous sex. However, additional wild adults will be used to supplement the broodstocks that <br />are developed from either the 5 X 5 di-allele cross or factorial crosses when they are available to increase the <br />effective population size and to reduce the risk of inbreeding. <br />Immediate broodstock development for four presumptive stocks is ongoing: 2 for razorback suckers (Middle <br />Green River and Upper Colorado River stocks), 1 for bonytail (Lake Mohave stock), and 1 for Colorado <br />pikeminnow (Lipper Colorado River stock). The Escalante Ranch-Green River razorback sucker broodstock <br />is being developed at the Ouray Endangered Fish Facility in Utah. The Upper Colorado River razorback <br />sucker broodstock is being developed at the Grand Valley Endangered Fish Facility, Grand Junction, <br />Colorado. The Lake Mohave bonytail broodstock will be cultured at Dexter National Fish Hatchery and <br />Technical Center, Dexter, New Mexico. The Upper Colorado River Colorado pikeminnow broodstock (17 <br />family lots) is being maintained at the Horsethief State Wildlife Area and in a backup refuge at Dexter <br />National Fish Hatchery, New Mexico. An estimate of about 10.3 acres of active ponds and 144 acre-feet of <br />water annually will be needed to maintain these broodstocks. <br />Currently our broodstock needs in razorback sucker is not meeting the 25x25 mated pairs. It has been difficult <br />to get older fish held over a year at the hatchery to spawn. In addition, collections of adults from the spawning <br />bar has been limited and when possible difficult. Recent attempts at collecting adults has resulted in four <br />females and 17 males; only 2 of the females produced sufficient eggs for brood stock development. Bonytail <br />are currently supplied from the Dexter National Fish Hatchery and Technical Center, but are based on a <br />relatively few adults. Humpback do not currently have a broodstock development plan in place. The <br />humpback chubs aze considered to be sufficiently stable. To enhance the population of pikeminnow, at least <br />in the upper Colorado River reach, the purposed method is to use stream side spawned progeny and grow out, <br />without the further development of a broodstock. <br /> <br />t <br /> <br /> <br />1 <br /> <br />t <br />1 <br /> <br />1 <br /> <br /> <br /> <br /> <br />1 <br /> <br /> <br /> <br />