Development of behavioral guidance systems for downstream migrant fishes has been hindered by a lack of understanding of natural migratory behaviors. Much of the existing data on behavior of downstream migrant salmonid juveniles is biased due to alteration of migratory behavior by capture methods, handling, use of hatchery fish, or unnatural experimental conditions. Predator avoidance and refuge-seeking are primary natural behaviors that may be used for guidance and protection of bypassed migrants in tailraces.