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active transport, fish are moved or lifted by some means of mechanical assistance; the fish are not required to voluntarily negotiate the barrier. Examples of active transport include trapping and trucking, fish locks, fish elevators and fish hoists with buckets. With passive transport, the fish are required to negotiate the barrier by voluntarily swimming through the fish passageway. Fish ladders are the most common example of passive transport. There are several important concerns that must be addressed when fish passageways are proposed as a recovery tool. Estimating the recovery value of fish passageways The relative contribution of a passageway to the recovery effort, as specified by the intent of the Recovery Implementation Program, should be a primary consideration when determining whether a fish passageway should be constructed at an existing barrier. Indeed this concern for the contribution toward recovery should be applied to all management efforts planned to aid the recovery of endangered fishes. Estimating the value of fish passageways as tools for recovery of Colorado squawfish is problematic, however, because the relative importance of movement restriction to the decline of the species is unknown. Therefore the likely benefits to the squawfish population of restoring some level of unrestricted movement around instream barriers are equally uncertain. Moreover, because no passageway can be 100 percent effective and pass all fish, the negative effect of the barrier on fish movement can never be entirely mitigated by a passageway. Care must therefore be taken when passageways are recommended for recovery because such structures can be 5