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Health.- Adults in Lake Mohave and in the Green River appear to be in good health. However, as with the humpback chub, handling and captivity sometimes injures and stresses these fish which leads to infection with bacteria and fungus. Disease organisms found on such fish are by no means a threat to the wild population as a whole. Razorback Sucker Distribution and Abundance Razorback suckers were infrequently caught in the mainstem river reaches during systematic sampling. Substantial numbers were caught in a few limited areas in the spring and early summer during special field investigations. The systematic sampling program produced only five razorback suckers in the Green River and ten in the main Colorado. Those of the Colorado exhibited no discernable trends in population concentrations with cap- tures being widely distributed from Lake Powell to near Rifle. In the Green, collections suggested that the greatest concentrations were in the moderate sandy reach between Split Mountain Gorge and Desolation Canyon. Special investigations conducted by CRFP and collections by other agencies accounted for 84 captures from three confined, localized areas that appeared to be spawning congregations or fish that were staging preliminary to spawning. These localized areas were in the confluence zone of Ashley Creek on the Green River, the Walter k'alker Wildlife Management Area gravel pit and the Clifton Pond gravel pit on the Colorado River. Three razorbacks captured and tagged at Ashley Creek were recap- tured during a three-week period. Five of 42 razorbacks captured and tagged in the Walker Wildlife Management Area and Clifton Pond were subsequently recaptured in the same area over periods of one day to one year. Razorback suckers were clearly rare and seemed to be relatively stationary except during the spawning season when they congregated in a very few areas. In the Lower Colorado River Basin, a similar situation exists. A few razorback suckers are taken from the Colorado Rivez below Parker Dam and some older adults are taken from Lake Havasu and Lake Mohave. Rowever, reproduction in the Lower river is also nonexistant or insignificant. Our investigations did not demonstrate any natural recruitment for these fish within recent times. Unless some significant recovery/ management actions are taken, continued survival of razorback suckers in the upper Colorado is doubtful. Migration~arid Movement Findings from previous studies by McAda and Wydoski (1980) have demonstrated that razorbacks can move 20 mi or more over several months and up to 80 mi in a few years.