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Only about 1,000 razor backs remain in upper Green River RAZORBACK. from page 1 backs may be unable to tolerate cold water and temperature fluctuations downstream of Aaming Gorge Dam. Also, there may not be adequate habi- tat, such as flooded areas off the river's main channel, which the young fish may use to survive and grow. Research may provIde answers Biologists working with the Recovery Implementation Program for Endangered Fish of the Upper Colorado River Basin are talcing sever- al steps to reverse lhis downward trend. In 1986, biologists with the U.S. Fish and Wildlife Service established the Ouray (Utah) fish Propagation and Experiment Station near Vernal. Tyus, the biologist who heads up the facility. stresses that their primary pur- pose is to conduct research on recov- ery. "We work on recovery, not just pro- ducing fish," Tyus said. "The largest population of razorback suckers remaining in a river environment any- where is in the Green River. If there is any chance of recovering the razOlback in the upper Basin, it's here." According to biologists, there are about 1,000 razorbacks in the upper Green River. Artificially producing the fish requires a mix of man and Mother Nature. Razoroacks in the wild are very old and when caught are easily stressed. To keep handling to a mini- mum, biologists take eggs and milt (sperm) from the fish "streamside" each spring. then release the adults back into the river. The eggs are fertil- ized, then brought back to the Ouray facility to be hatched in incubators. Razorback prognosis poor Most of the fish produced at Ouray are used in studies on diet, temperature preferences, genetics, growth and sur- vival. Other fish are stocked in the Green River to evaluate their use of the habitaL Since 1988. biologists have released about 5,000 2-to-5-inch razorbacks. Whether any of these fish have sur- vived to adulthood is unknown. But based on data from the lower Colorado River Basin (below Lake Powell), the prognosis is poor. . "Millions of razoroacks have been stocked in the lower Colorado River Basin. but few fish have been captured. and no reproducing populations have been established," Tyus said. "Without improving the habitat, stocking has not proven successful" Beginning this year, before the razorbacks are stocked they will be implanted with a small tag that can be detected electronically. 111is may make it easier to evaluate the success of future stocking. Remove fish now, stock back later Another tactic used elsewhere in the upper Colorado River Basin is to remove adult fish from rivers and hold them in protective ponds or hatcheries for use as brood stock. Last swnmer biologists removed four adult razor- backs from the Colorado River and Highline Reservoir, near Grand Junction, and 15 from the San Juan River and neartJy Lake Powell. These fish are being held in hatchery facilities at Dexter, NM., and Ouray. 'The No. I priority for razoroacks is to collect as many as we can from the Colorado River before they go extinct in the wild," said Recovery Program Director John Hamill. According to plans currently being developed, razor- backs probably will be stocked in the . Colorado River beginning in 1993. This strategy will buy time for researchers to discover why previous stockings have failed and to detennine ways to improve the fishes' chances of surviving and successfully reproducing in the wild. For example, the habitat may be improved by establishing adequate flows for the fish. Biologists can lleter- mine if the fish become "imprinted" to a specific site and will spawn only in that area. They can evaluate where razoroacks should be stocked and at what age. They can also detennine if there are genetic differences in fish from different river systems. "When we start a razOlback sucker breeding program, we will have as broad a genetic base as possible," Hamill said. .......R~O~~~.pl~:..f~ri...h~~Pb~clC,..bBri~~li~b 6ff~~&i t()'ptibli~""~":/".'.:''''''''.. ....... .......... ,:":-,,::,,:'::.":.: ... ..... ......... .... . ........ ............ ............"....... . .... .....................:..:..,. .. 8 .. ............:.....:.,::