Physiological Measures of Smolt Quality at Time of Release Successfully Predict Relative Smolt to Adult Performance in Hood River Spring Chinook Salmon (Part 1)

We studied the environmental effects of differential hatchery rearing on juvenile and adult phenotype by rearing a single stock of Chinook Salmon, Oncorhynchus tshawytscha, at three different hatchery facilities across three brood years (2008–2010).  Data collected from measuring a variety of physiological parameters in the juveniles (Part 1) was then used to predict relative adult return rates (Part 2).  Smolting, size at release and early male maturation rate varied consistently across rearing locations among years.  Differences in seasonal thermal regimes and associated growth profiles among the three facilities were correlated with juvenile phenotype.  This experiment provided an opportunity to isolate environmental from genetic effects on phenotypic plasticity and salmonid life history and highlights the potential impacts of early rearing on adult performance.