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IMF Inc Ac1G??A I /s?i?t, JU7 Zi 18 ?? 1G 85 TAI'tT 'f9f [HE RAZORBACK SUCKER XYRAUCHEN TEXANUS r IN THE COLORADO RIVER UPSTREAM FROM LAKF PIWFL.L Charles W. McAda U. S. Fish and Wildlife Service 529 25 112 Road, Suite B-113 Grand Junction, CO 81505 The razorback sucker Xyrauchen texanu?? is distributed throughout the upper oolorado River from upper L.akF? F'c?we?1 ra Rit le. CO. However, few specimens have been collected in recent years ana the species is consiaerea rare. (he razorback sucker is listed as endanqered by the state of Colorado and is protected by the state of Utah, but it currently receives no federal protection. The Fish and Wildlife Service (FWS) has collected 23 razorback suckers from the upper Colorado River since 1982. lhis number compares with 165 subadult and adult Colorado squawfish Ptychocheilus lucius and 300 adult humpback chub Gila cpha collected during the same time period with equivalent effort. The latter species are listed as endangered by FWS. Colorado Division of Wildlife crews collected 7 razorback suckers in the Colorado River between 1979 and 1984 (personal communication, John Hawkins, Colorado State University). They estimated that 50 or more Colorado squawfish f were handled for every razorback collected. One razorback sucker has been collected in the Gunnison River since 1980 (personal communication, P. Holden, Biowestl. Razorback suckers are infrequently collected from the Dirty Devil and Colorado River arms (personal communication, K. Lashmett, Bureau of Reclamation) and San Juan River arm (personal communication, W. Gustaveson, Utah Division of Wildlife Resources) of upper Lake Powell. Current evidence indicates the razorback sucker i,j in a tenuous position in the upper Colorado River. Of the four rare larqe-river fishes native to the upper basin, only the bonytail G. e_le ans is less common. In addition, no evidence of successful recruitment to the population has been found in recent. year,,,. The lack of recruitrr,_nt indicates that t.ht;? population will continue to decrease as individuals aqe and die. Adequate funds for research and management are needed to identify reasons for the continuing population decline and to reverse the trend.