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protected as endangered species under provisions of the Endangered Species Act of 1973 {U. S. Fish and Wildlife Service 1986). The razorback sucker, a candidate species for federal listing, is protected by state statutes in Arizona, California, Colorado, Nevada, and Utah (U.S. Fish and Wildlife Service 1985, 1987a). In the lower Colorado River basin (below Lee Ferry, AZ), the Colorado squawfish has been extirpated, relict populations of bonytail chub and razorback sucker remain in some impoundments but neither species are presumed self-sustaining, and humpback chub reproduce only in the Little Colorado River (Hinckley 1973, 1983; Kaeding and Zimmerman 1983; C.O. Hinckley,-pers. comm.). In the upper Colorado River basin, Colorado squawfish persists in the Yampa and lower Green {below the confluence of the Yampa River) rivers, the upper Colorado River mainstream, and the lower San Juan River (Archer et al. 1985; Meyer and Moretti 1988; Tyus 1990). The humpback chub is presently self-sustaining in the Yampa River and upper Colorado River (Archer et al. 1985; Karp and Tyus, in review). The razorback sucker persists in the lower Yampa and Green rivers, the mainstream Colorado River, and the lower San Juan River, but there is little indication of recruitment in these remnant populations (McAda and Wydowski 1980; Meyer and Moretti 1988; Lanigan and Tyus 1989; Tyus and Karp, in review). Bonytail chub are extremely rare in the upper Colorado River basin (Valdez and Clemmer 1982; U. S. Fish and Wildlife Service 1987a). All four fishes have been extirpated in the Green River between flaming Gorge Dam and the Yampa River confluence, presumably due, in part, to the loss of usable habitat following closure of the dam (Vanicek et al. 1970). The Yampa River supports all of its native fish fauna including self- sustaining populations of some of the rare species and is considered important to the maintenance and availability of usable rare fish habitat in the downstream Green River (Tyus and Karp 1989). Study Abstracts The following section abstracts all reports completed under the Flaming Gorge Interagency Agreement of 1986. These reports are generally organized under the appropriate study; however, there was some overlap between study reports. Abstracts-were taken from each respective report. Study 1: Summer and Fall Requirements of Age-0 Colorado squawfish in the Green River. Report 1- Distribution, Abundance, Habitat use, and Growth of Young Colorad o squawfish in the Green River Basin, Colorado and Utah (Tyus and Haines, in review). Larval and postlarval Colorado squawfish were collected in stream drift (N=601) and shoreline habitat (N=3,079] in July and August. The young fish appeared in drift nets about 36d following peak spring discharge and thereafter for 4-7 weeks. Drift netting and shoreline seining in 1979-85 and 1987-88 indicated that young Colorado squawfish moved an average of about 160km downstream of two spawning areas by August of each year. Postlarval squawfish were most abundant in shoreline embayments (backwaters) in September and October (N=6,459), and two nursery areas differed in average backwater temperatures and maximum depths (18.7°C and 29.6cm in one area, 13.1°C and 36.6cm in the other). The fish occurred most frequently (80%, N=5,043) in 6