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<br />54.1 <br /> <br />Experimental Stocking of Razorback Sucker <br />Fiscal Year 1997 Project Proposal <br />U.S. Fish and Wildlife Service, Region 6 <br /> <br />Background: <br /> <br />Razorback sucker are native to the San Juan River. At present this species is extremely rare in the <br />San Juan. In order to gain information on habitat use, possible spawning areas, and survival and <br />growth rates of hatchery-reared razorback sucker in the wild, it was necessary to experimentally <br />stock a small number offish. The information obtained from this effort should help provide <br />recommendations to guide future augmentation efforts. Integration of razorback sucker <br />experimental stocking data with data from adult fish community monitoring studies, Colorado <br />squawfish macrohabitat studies, contaminants studies, habitat mapping studies, and non-native <br />species interaction studies, will help to provide flow recommendations for reoperation of Navajo <br />Reservoir as well as helping address objectives 5.1 through 5.5 in the San Juan River Long Range <br />Plan. <br /> <br />Eight adult razorback sucker from the San Juan River arm of Lake Powell were spawned at <br />Ouray National Fish Hatchery in the spring of 1992. Most of the offspring from those paired <br />matings were kept as refugia stock. The excess offspring, above and beyond refugia needs were <br />reared at Wahweap ponds (Utah Division of Wildlife Resources) near Lake Powell. Fifteen of <br />these razorback sucker were surgically implanted with six-month A VM radio tags and stocked in <br />March 1994, five at each of three stocking sites. The remaining fifteen fish were reared to an <br />average size of 673 grams, implanted with 23-month A VM radio tags in September 1994, and <br />were stocked in October 1994, at the same three stocking sites. All radio-tagged stock were PIT- <br />tagged. The three experimental stocking sites along the San Juan River are all between Shiprock, <br />New Mexico and Bluff, Utah (RM 136.6, 117.5, and 79.6). An additional 656 PIT-tagged fish <br />were stocked, in November 1994, in even numbers at the above three sites as well as a fourth site <br />just below Hogback Diversion (RM 158.5). In September 1995, 16 radio-tagged razorback <br />sucker (23-month A VM tags) were stocked at the Hogback Diversion site. On October 3, 1996, <br />237 PIT -tagged razorback sucker, including ten additional radio-tagged fish, were stocked at RM <br />158.5. To date, 5.0% (48) of stocked razorback sucker have been recaptured. In addition, one <br />PIT -tagged razorback sucker that was stocked on August 8, 1995 at Piute Farms (RM 0.0) by the <br />Utah Division of Wildlife Resources, was recaptured on May 21, 1996 at RM 58.0. Also, as <br />many as eight of the 30 sonic-tagged razorback sucker stocked on November 1 & 2, 1995 (Lake <br />Powell miles 24.0 and 43.0) by National Biological Service were contacted in the lower 38 miles <br />of the San Juan River during the 1996 field season. Follow-up monitoring will continue on adult <br />sampling trips and at least six ground monitoring trips through September 1997. Aerial tracking <br />was conducted via helicopter in December 1995, however this technique proved unsuccessful and <br />has been discontinued. Radio-tracking will also be done during other research trips throughout <br />the year and opportunistically during fixed-wing aerial flights for channel catfish. <br /> <br />4 <br />