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squawfish appear to exhibit the greatest movement.' Sub-adult and adult Colorado squawfish sometimes exhibit long-distance movement to habitats essential to different life stages of the fish. Migration of over 200 miles has been documented. Most migration has occurred near/during the spawning period and included movement to and from spawning areas. Razorback sucker also show tendencies to migrate, although little is known about the extent and range of their movements. Radiotelemetry data obtained from humpback chub in the upper basin indicate their movement is restricted to a small area. Unfortunately, because of their scarcity, no movement information has been collected for bonytail. The Service is mandated by provisions of the Act to provide conservation measures to protect and perpetuate these fishes and enhance their habitat. An important goal of this effort is to restore these species to enough of their former range so that their population numbers are no longer declining. The ultimate goal is to increase the population to a level that allows delisting. Dams and irrigation diversions on mainstem rivers and their tributaries in the Colorado River basin constructed in conjunction with water projects are impediments to upstream movement of adult endangered fishes. Barriers that block stream passageways contribute to the loss of historic habitat for these fishes and possibly their decline, and may be one factor that led to loss of Colorado squawfish in the lower Colorado River basin below Glen Canyon Dam. Fish passage facilities constructed and operated in the northwestern and northeastern United States have successfully passed numerous species of anadromous, salmonid fishes over or through natural and manmade migration barriers. No passage facilities have been constructed on mainstem rivers in the upper Colorado River basin. However, the rationale was that if those fishes of the upper Colorado River basin that showed tendencies to migrate 2