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a '-:) . r,", , " ".' G:':l t.>J 6 in the wild. Currently there are not enough wild fish available in the river either for research purposes or, probably, for spawning aggregations to take place. There is also the risk of delaying stocking or stocking too few fish. This could result in the loss of the few remaining fish (both wild and captive) and the genetic resources they represent to old age or unforeseen circumstances. Artificial propagation and release of hatchery-reared razorback sucker is a potentially vital component to recovery of this species. In March 1994, 15 radio-tagged juvenile razorback sucker were released, five per site, at three stocking sites (RM 136.6, 117.5, and 79.6-modified from the original stocking plan). These fish were equipped with six- month transmitters that expired in September 1994. In October 1994, an additional sixteen radio-tagged razorback sucker, equipped with 22-month transmitters, were released in equal numbers at these same three sites. In November 1994, 656 PIT-tagged razorback sucker were also stocked in equal numbers at four sites, the three above mentioned and RM 158.6, to allow for greater probability of recapture during monitoring. In September 1995, an additional 16 radio-tagged razorback sucker, equipped with 22- month transmitters, were released at RM 158.6. All stocked fish were F1 progeny of adult razorback sucker from the San Juan River arm of Lake Powell. At present 40 of the 704 experimentally stocked fish have been recaptured. Thirty-seven were PIT-tagged and three were radio-tagged fish. These fish were distributed from RM 158.6 to RM 38.1. Currently, few radio-equipped fish from the October 1994 and September 1995 stockings remain in the system to provide needed habitat use and distribution information. The reasons for this include 1) mortality or expulsion of radio transmitters (at present three transmitters are known to be stationary); long downstream displacements following stocking, possibly resulting in emigration to Lake Powell (this phenomena was documented in March 1995 by the capture of one individual in Lake Powell and the location of several other individuals in the canyon reaches below RM 68); 3) or tag failure (in 1995 and 1996, three radio-tagged razorback sucker were recaptured that had failed tags). These phenomena seem to be more pronounced in radio-tagged razorback sucker than in fish with PIT tags only. However, if winter habitat use data is to be gathered in 1996/1997, additional radio-tagged fish will be needed. The proposed 1996 stocking effort would make use of 300 razorback sucker from the Wahweap Warmwater Fish Hatchery facility operated by the Utah Division of Wildlife Resources. Ten of these fish would be surgically implanted with 13-month transmitters. All 300 fish will be stocked at RM 158.6 in late September 1996. Stocking at this site should allow for greater retention of these fish in the San Juan River than at downstream sites. Differential overwinter survival between newly stocked razorback sucker during a low winter base flow period (1996/1997) will be compared to that of a similar stocking during a normal winter base flow period (1994/1995). Also the ability of newly stocked fish to survive during low winter base flows can be compared to that of stocked fish that have already had two seasons to adapt to riverine conditions. In addition, the ten radio- tagged fish would allow for the collection of much needed winter habitat use data during