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consequently, slowly starved. Another reason for the presumed low survival is that radiotagged razorback sucker expelled or lost the radi otag following stocking in the Upper Colorado and Gunnison rivers. The fish could have survived or died following loss of the tag. Some razorback suckers implanted with AVM@ internal radiotags and held in ponds at Wahweap, Utah, lost their tags within one week. Researchers believed that, following surgery, fish rubbed their abdominal region against the concrete kettle and loosened the sutures resulting in the tag falling out. Twice in 1994 and once in 1995, when fish were implanted with radiotags, tag loss was about 50% approximately within one week. In 1996, tag lost was about 30% (Personal communication, Dale Ryden). Tag loss was- essentially zero after-one week. Expulsion may explain the constant downstream movement of the radiotag in this study and it ultimately coming to rest and being lodged in the same location. Although unlikely, tag failure of a number of radiotags or poor reception capabilities of the radio receiver may be other reasons for low detection and thus assumption of poor survival. Mortality associated with netting, handling, and radiotag surgery was unlikely. One razorback sucker was implanted with a non-functional radio tag April 1994 and held in ponds at Horsethief SWA for observation until March 1995. At that time, this fish along with five other sub-adult and adult razorback sucker were implanted with radiotags and held in ponds at Horsethief for further observation. Two of these six razorback sucker died 27 July 1995. Death was attributed to a bacterial infection (Personal communication, Mike Baker). The infection was not associated with the radiotag surgical incision because other razorback sucker broodstock held in the same pond also were infected at the same time. Therefore, four radiotagged razorback sucker survived in the pond, one for about 18 months following surgery and three others for about 6 months following surgery. None of these fish lost their radiotags while being held in the ponds. These same four surviving fish were stocked in the Gunnison River September 1995. The fate of razorback sucker stocked in 1994 and 1995 in the Upper Colorado and Gunnison rivers may never be known or at least not for several years. However, razorback sucker are long-lived and fish that were missing or might have lost their radi otags could have survived and might be recaptured in future years. If these fish are recaptured, they could be identified by PIT tags. Pond-reared razorback sucker stocked into the San Juan River have survived for almost three years and appeared in good condition when captured (Ryden and Pfeifer 1996). Furthermore, the recapture rates for larger stocked razorback sucker (mean and range [TL mm]: 364; 204-482) were greater than smaller sizes stocked (mean and range [TL]: 190; 100-374). During sampling of the San Juan Ri ver over a period of 31 months fol l owi ng the stocki ng of these fi sh, onl y three of the 478 (0.6X) smaller-sized razorback sucker were recaptured whereas 46 of the 461 (10X) larger-sized razorback sucker were recaptured (Personal communication, Dale Ryden). Neither of these two groups of razorback sucker stocked in the San Juan River in 1994 and 1995 had been conditioned prior to release. Therefore, stocking pond-reared fish without any prior conditioning does not guarantee failure. For razorback sucker stocked in the Upper Colorado and Gunnison rivers, some of the mortality might be attributed to lack of conditioning, but many other factors could be involved. 17