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on144~ ~ I o o fl U . I o .~ ~ o 20 Shiprock, near Bluff, and in the inflow area of Lake Powell. One adult Colorado squawfish was also collected in the San Juan Arm of Lake Powell. Only one razorback sucker has been collected in the San Juan River since systematic research began in 1987. During that period, however, several specimens of razorback sucker were captured in the San Juan River inflow area of Lake Powell. Many of the specimens of razorback sucker captured were in spawning condition, but no reproduction or recruitment was documented. Although archaeological evidence and two specimens (of unconfirmed identity) indicate bony tail historically occupied the San Juan River, no individuals have been captured since systematic investigations began in 1987. Adults of Colorado squawfish are found in habitats ranging from low-velocity interfaces of tributary mouths and the San Juan River to main channel, rapid velocity deep runs. Within the San Juan River, the extent and success of annual spawning, recruitment, or survival of young Colorado squawfish has not been determined. Spawning is believed to occur in the San Juan River during July and perhaps August. The location of spawning areas in the San Juan River is not known, but successful Colorado squawfish reproduction does occur when conditions are favorable in the river as was evidenced during the 1987, 1988, and 1990 surveys. Young-of-year Colorado squawfish are typically captured in shallow backwater or side-channel habitats with silt and sand substrates and little or no current. 'r U Adults of razorback sucker normally inhabit a variety of habitats including quiet eddies, pools,and mid-channel runs. They are usually found over a sand or silt substrate, but can also occur over gravel and cobble bars in the spring during spawning. Spawning may occur in Lake Powell, or lowermost San Juan River, but recruitment of young-of-year razorback sucker has not been documented in the San Juan River. . II ~ Within the river, the overall range of Colorado squawfish and razorback sucker and that of individuals of each species are not known. The extent or types of habitat normally occupied by adults of either species in the San Juan River is poorly known. Spawning and nursery habitats of. neither sPecies have been identified or characterized. :1 ~ --, o 3.1.2 Course of Action 3.1.2.1 Research U lJ a. Intensive studies will be conducted to determine the relative abundance and distribution of endangered fishes,