In‐Hatchery Survival of Chinook Salmon Using Natural and Hatchery Broodstocks

ABSTRACT

Natural‐origin Chinook Salmon Oncorhynchus tshawytscha have been integrated into hatchery broodstocks to mitigate the potentially negative effects of domestication in‐hatchery programmes. However, uncertainty exists about the in‐hatchery performance of the offspring of natural‐origin parents relative to the traditional hatchery broodstocks. Therefore, the objective of this study was to evaluate in‐hatchery survival of Chinook Salmon from natural and hatchery broodstocks. In‐hatchery survival of natural and hatchery Chinook Salmon broodstocks was monitored from fertilization to release at three fish hatcheries in the Salmon River basin, Idaho from brood years 2015 to 2023. In‐hatchery survival from green egg to release was generally greater than 0.75 among hatcheries for both integrated and segregated groups (only hatchery‐origin adults in broodstock). Small, but statistically significant, differences between the integrated and segregated stocks and within the integrated crosses were observed. Both parental origin and rearing environment (i.e., fish hatchery) influenced survival, but the direction of that influence was variable across the study. Results from this study suggest that using natural‐origin adults in the broodstock does not cause substantial in‐hatchery survival consequences. Implementation of integrated broodstocks can reduce risk to wild populations while still reaching hatchery production targets.