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b. The highest mortality is expected for 4-inch fish, less for 8-inch fish, and the lowest mortality for 12-inch fish. Mortality for all size groups will be highest shortly after stocking. Limited data from stocking razorback suckers in the San Juan River suggest that large fish have survived better than smaller ones. c. Most stocked fish will move downstream after stocking-many miles in some cases. Most movement will probably occur fairly quickly. However, downstream displacement will probably continue for weeks or even months. Stocked fish in the San Juan River have moved as far as 60 miles downstream. d. Fish will survive best if released after spring runoff when they could be rapidly washed downstream, but before winter when water temperatures decrease substantially. 3. Source of Fish The razorback sucker stocking plan for the Green River (USFWS 1995b) identifies using wild razorback sucker larvae from natural propagation to augment the current population. However, since no razorback sucker larvae have been found in either the Colorado or Gunnison rivers and adult numbers are far less than that encountered in the Green River, razorback sucker to be stocked into the Gunnison and Upper Colorado rivers will be produced from captive-reared broodstock. Fifteen wild adult fish (seven females and eight males) obtained from four different sources in the Upper Colorado River Basin and currently being maintained in ponds at Horsethief SWA will be used to produce offspring for stocking and for future broodstock. These wild fish were collected from the Colorado River arm of Lake Powell (two males, two females), the Upper Colorado River near Grand Junction (two males, two females), the San Juan arm of Lake Powell (three males, one female), and Etter Pond (one male, two females). Captive spawning of these 15 fish will follow the appropriate breeding strategy as outlined in the Genetics Management Guidelines (Williamson and Wydoski, 1994) such that the probability of inbreeding depression will not exceed five percent. Fish will be produced from paired matings of known parents. Because of the limited number of wild fish available, each fish will be mated with more than one individual of the opposite sex Each family lot will be maintained separately until they are large enough to be PIT tagged-about four inches long. All fish produced from these controlled matings will be PIT tagged so that their genetic background will be known. After tagging, young fish from different lots will be combined in rearing ponds. Each family lot will be represented equally in the fish held for brood stock, as well as those stocked into the wild (Allendorf 1993). Certain paired matings may have to be repeated in consecutive years to even fish numbers because of differential survival among lots. 6