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encounters involve just a few individuals, although R.R. Miller seined 6,600 larvae and small juveniles along warm, shallow margins of the Colorado River at Cottonwood Landing, Nevada in 1950 (Sigler and Miller 1963). Taba et al. (1965) collected a few juveniles from backwaters in the Colorado River near Moab. Smith (1959) caught two young fish on the Colorado River in Glen Canyon, one from a backwater and one from a creek mouth. Gutermuth et al. (1994) captured two small juvenile razorback suckers in a silty backwater in the lower Green River in 1991. Juveniles also have been collected in the middle Green River. Two juveniles (59 and 29 mm) were collected in a main channel backwater in 1993 and 28 juveniles (74-124 mm) were collected from Old Charley Wash, a wetland adjacent to the Green River, in October 1995 (Modde 1996). Another 45 juvenile razorback suckers were collected from Old Charley Wash in August 1996 (T. Modde, USFWS, pers. comm., 1996). Additional information about the movement of juvenile razorback suckers has been obtained from 55 hatchery-reared fish that were tagged with sonic transmitters and released into lakes Mojave and Powell. These fish utilized backwaters and coves, and more than half of the tracked fish utilized flooded and emergent vegetation, and rock cavities as cover (Mueller and Marsh 1998). In another study, 33 juvenile razorback suckers were tagged with sonic transmitters and released in Neskahi Wash and Zahn Bay of the San Juan arm of Lake Powell (23 and 42 miles, respectively, above the historic river mouth). Twenty three of these fish were located in the upper 32 miles of the Lake Powell-San Juan River inflow area and were found in association with flooded vegetation. Eight individuals of the fish were tracked for 21 months, and exhibited an overall upstream movement to reach and occupy the lake-reservoir mixing zone (near Paiute Farms, river mile 42 to 62) (C. Karp, U.S. Bureau of Reclamation, pers. comm., 1998). Young razorback suckers presumably require quiet, warm, shallow water (e.g., eddies and backwaters) for nursery habitats in riverine environments. Backwaters provide quiet, warm water where there is a potential for increased food availability. During higher flows, flooded bottomland and tributary mouths may provide still water. Tyus and Karp (1989, 1990) identified the importance of flooded bottomland for the growth of young fish. Many of these off-channel habitats have been eliminated in the Colorado River basin by construction of mainstream dams, diking of floodlands, and channelization (Beland 1953, Tyus and Karp 1989, Osmundson and Kaeding 1990). Gravel-pit ponds connected to the river may provide a substitute for inundated riparian cottonwood bottomland, other wetlands, and oxbow channels. However, these habitats also support nonnative predatory fish, such as largemouth bass, catfish, and green sunfish, which feed on young razorback suckers, or other smaller nonnative fishes such as red shiner and fathead minnow that are known to consume the larvae or display agonistic behaviors (Minckley et al. 1991, Mueller 1995, Tyus and Saunders 1996). In reservoirs, coves can provide warm, shallow shorelines suitable for nursery habitat (Minckley et al. 1991). 12