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C) : ,.~) C:.;J . ( \.~ . C':l 0) 9 the experimental stocking study in the San Juan River in 1994 and 1995 were stocked into Lake Powell at Piute Farms Marina in August 1995. In late summer and fall 1995, approximately 2000 razorback sucker were transferred to Wahweap from Ouray NFH (900 fish) and Valley City NFH (1100 fish). These fish are also F1 progeny from the 1992 paired matings at Ouray NFH, but represent different parental lineage than those previously held at Wahweap. Currently, approximately 1650 F1 juvenile razorback sucker are being reared at the Wahweap facility. A subsample of these fish taken in June 1996, shows the mean total length (TL) of these fish to be 264 millimeters (mm) and mean weight to be 220 grams, with some individuals ranging as large as 335 mm TL. Assuming normal growth rates in a grow-out pond environment, the mean TL of these fish should be approximately 300 mm TL by late September 1996. Stocking fish of this size should aid in avoiding high mortality rates due to predation by non-native species such as channel catfish, which are abundant in the San Juan River (Platania 1990, Ryden and Pfeifer 1993). In support of stockings conducted in 1994 and 1995, an additiona/300 razorback sucker from the Wahweap facility would be stocked at Hogback Diversion (New Mexico), RM 158.6. All fish to be stocked are presently PIT-tagged. Fish would be weighed, measured, checked for general health. Ten of these fish would be surgically implanted with an AVM 13-month radio transmitters, one month prior to stocking. Surgically implanted fish will be held in separate enclosures and closely monitored. This will allow for implantation of a radio transmitter into another fish should a mortality occur. In late September 1996. all 300 fish would be stocked at RM 158.6. Stocking at this upper-most of the four sites should allow for retention in the river system. even after the downstream displacements associated with post-stocking stress. Following stocking, razorback sucker would be monitored during as many as four trips in the winter of 1996/1997 and several trips in the spring and summer of 1997. As with the previous efforts, sampling would consist of seining and trammel netting in the areas where razorback sucker were stocked and where radio-tagged fish are present. All sampled habitat would be characterized as to its physical attributes as well as its relation to adjacent macro habitat types. Numbers and sizes of fish found in each sampled habitat would be recorded. Razorback sucker collected would be weighed, measured, scanned for a PIT tag, have scale samples taken, tissue samples taken for contaminants analysis, and be examined for general health and reproductive status. If a wild razorback sucker is captured, researchers would follow the above procedure as well as PIT-tagging, taking two tissue samples for genetics and contaminants analyses, and surgically implanting a radio tag. Additional monitoring would take place during adult fish community monitoring trips in the spring and fall. Razorback sucker captured during these sampling trips would also be examined for all the above criteria. Radio tracking would take place on all above mentioned sampling trips, as well as during other research efforts.