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Upper Mainstem: Since the late 1960's two suspected bony tail have been, collected from the upper Colorado mainstem; one adult cap- tured and returned in Black Rocks by USFWS in August 1984 and one adult angled by a fisherman near Wahweep, Lake Powell in May 1985, and preserved by the UDWR. The definitive identity of these speci- mens is unknown to us. San Juan-Colorado: A suspected adult bony tail was captured in Cataract Canyon in August 1985 along with a suspected YOY (Valdez et ale 1985). The morphology of this fish is very similar to suspected specimens from the Green River (Tyus et al. 1982), and the presence of bony tail genes is undoubtable. However, the fish is different than the Lake Mojave form. Remarks: The bony tail form may no longer exist in the upper basin, except perhaps as an incidental species with only a few old individuals surviving. Razorback Sucker Green: Although rare in the Green River, the razorback sucker is more common there than elsewhere in the upper basin, as evidenced by catch records. 'The capture of 250 razorback from 1981-85 indicates their distribution was sporadic, and absent from turbulent canyons. The center of distribution occurs in flatwater stretches of the upper Green River and localized areas of major tributaries, where three spawning reaches were confirmed by the collection of 64 razorback in breeding condition, of which 34 had strippable sex products. A com- parison of catch data with other native suckers and the Colorado squawfish indicates that the razorback was less than 1% as abundant as the flannelmouth sucker and less than 10% as abundant as the Colo- rado squawfish. The lack of smaller size classes (less than 400 mm TL) suggests a lack of recruitment, although some larval razorback were collected below spawning areas in 1984. '- Upper Mainstem: Few razorback have been collected in the upper Colorado River since 1981. There continues to be a lack of young fishes, indicating reproductive success, and most of the fish captured appear to be rather old adults. Studies of fish larval drift in 1983 near Parachute, CO yielded one "possible" YOY razorback sucker frqm the same location as the capture site of the dult in 1981, RM 220.7 (Valdez et al. 1985). Additional investigation w th electrofishing, seining, and drift netting from RM 188.2 to 193 fa led to yield any razorback sucker (Valdez et al. 1985). -26-