Physiological Measures of Smolt Quality at Time of Release Successfully Predict Relative Smolt to Adult Performance in Hood River Spring Chinook Salmon (Part 2)

We studied environmental effects on smolt physiology, smolt migration, smolt to adult return and age of maturation of Hood River stock spring Chinook salmon Oncorhynchus tshawytscha reared at three different hatchery facilities across three brood years (2008-2010). We produced a rank of smolt quality for fish reared among the sites in each year. Each rearing group was marked with PIT tags and we calculated migration rates and the smolt to adult survival rate (SAR) of the PIT tagged fish to relate the physiological measures to migration and adult survival. We found that the rearing groups had significantly different migration rates and survival rates to adulthood and that the ranking of smolt quality derived from the physiological sampling effectively predicted the relative SAR among the rearing groups. We also observed overall differences in age at maturity among rearing groups. We suggest that the results from this research could be used to refine hatchery-rearing practices to maximize the quality, and ultimate survival rate, of hatchery reared spring Chinook salmon.