Born to be Wild? Development Patterns of Chinook Salmon, Oncorhynchus tshawytscha, and Steelhead, O. mykiss

Migration patterns and survival of juvenile spring Chinook salmon, Oncorhynchus tshawytscha, and steelhead, O. mykiss, are related to the conditions experienced during their passage downstream. We analyze morphology, behavior, and physiology of hatchery-origin and wild juveniles to produce hatchery-origin juveniles with the migratory and fitness phenotypes of their wild counterparts. Our rearing procedures are judged by survival of our juvenile fish in the North Santiam and McKenzie Rivers. We have evaluated the effects of temperature, rearing density, diet formulation, and substrate type on the development of juveniles by assessing growth patterns, body condition, morphology, proximate and fatty acid composition, and behavior.  In addition we assessed behavioral differences in spatial orientation such as surface versus bottom orientation, and fish that move downstream versus those that stay in position. Our experimental diet formulations produce growth patterns consistent with project goals. Density has a significant effect on growth patterns and fin condition; however, outdoor rearing apparently reduces the density effect. Behavioral traits associated with movement pattern (downstream movement and position in water column) are apparent immediately following swim-up. Additional behavioral assays and assessments of body condition, morphology, and growth patterns will determine the significance of these in terms of juvenile life history.