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The status of fishes is designated as: endemic - a species found only in the Colorado River Basin; native - a species recent to the Coloradc River Basin but occurring there before introductions by man; exotic - a species newly introduced into the Colorado River Basin (non-native); threatened - a species or subspecies which may become endan- gered in the near future; or endangered - a species or subspecies in danger of extinction. The current status of the four endangered fi~hes was obtained by a comparison between the results of referenced 1982-85 studies and those obtained from 1975-81 data presented by Tyus et al. (1982). Where obvi- ous changes in distribution, new extensions, or better catch per effort data exists, these recent developments are noted. Because source materi- al varied widely in sampling design and effort, it was necessary to use judgement in many cases for designating relative abundance and status. Other unpublished sources may have been overlooked by the authors, but no other major field studies were conducted in the Upper Colorado River dur- ing 1982-85. RESULTS Colorado squawfish Green: Catches of young, juvenile and adult Colorado squawfish continue to be an order of magnitude higher in this basin than else- where. Since 1981, the discovery of a second major spawning area in this basin (Tyus 1985) emphasizes the importance of the Green River and its tl'~butaries for Colorado squawfish. During some good repro- ductive years, young of this species are locally common in productive nursery habitat. Unfortunately, abnormally high summer-fall discharges fronl Fla~ing Gorge Dam have been linked to failure of the 1983 and 1984 year classes (Jones and Tyus 1985). The construction of Taylor Draw Dam or. the White River near Rangely, Colorado has further fractionated its range, and the loss of migrating adults from the upper White River to the Yampa and Gray Canyon Spawning Areas (Tyus et al. 1982, Tyus and Jones 1984) will result in a potential decrease in reproduction. Upper Mainstem: USFWS observed that 1982-84 movement of radio- tagged Colorado squawfish in the Upper Colorado River was greatly re- duced from that se~1l in the Green and Yampa Rivers (Archer et al. 1985). Most movement occurred during the presumed spawning period in July and August, but concentrations of adults were not observed, as was seen in the Green and Yampa Rivers. Spawning in the upper Colorado mainstem may occur in several locations, but no specific spawning site has been located. Systematic seine sampling by USFWS and Colorado Division of Wildlife (CDOW) (Haynes et al. 1984) for post-larvae and age-O squaw- fish in the upper Colorado River extended the previously known distr;- -23 r 1 j , I l \ I I I I r r ~ r f y D I I ~ 1 ! i , t t: