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expensive and their value to recovery is unknown. The recovery value of fish passageways needs to be evaluated as part of planned studies. When passageways may be important to recovery There may be a variety of situations in which the provision of passage may benefit the recovery of Colorado squawfish. An obvious one is when the existing barrier prevents access of adult fish to the only suitable spawning habitat, and thus spawning does not occur. This situation would be similar to that for the Pacific salmons, for example, species whose populations have declined dramatically, in large part because Columbia River dams prevent the adult fish from reaching headwater spawning streams. If access to a limited amount of habitat occurs, spawning may take place but the resulting young are too few to allow adequate recruitment to the adult stock. As a result, the adult stock would be small and would be considered to be "spawning habitat" limited. In addition, limitation of spawning habitat availability might force genetically distinct stocks to spawn in a common habitat, thus leading to interbreeding and possible loss of genetic uniqueness between stocks. A second situation in which the provision of fish passage might benefit recovery is when the availability of nonspawning habitat (e.g., wintering-feeding habitat) for adult fish is limiting the size of the adult population. In this case, movement barriers might prevent access to suitable adult habitat and the adult population could be described as being "adult habitat" limited. In both of these examples, the effect of the movement barrier is to further limit the range of the species. The negative effect of the movement barrier on the population 6