Effect of Male Age on Spawning Success of Hatchery and Wild Chinook Salmon in Wild and Hatchery Environments

Hatchery propagation can lead to marked changes in the age at maturity of propagated species, typically with a shift toward maturity at younger ages.  Understanding the mechanisms and consequences of a shift toward earlier maturity is important for evaluating the effects of hatchery supplementation on wild salmon populations.  Whole population pedigree analysis is a powerful tool for evaluating the genetic basis of variation in age-at-maturity and its micro-evolutionary consequences.  Here, we report on the effect of male spawning age on male fitness in Wenatchee River spring Chinook salmon in both wild and hatchery environments.  By using a 2+ generation pedigree, we can evaluate both the relative fitness of hatchery produced fish that return to spawn in the wild environment at a variety of ages and the heritability of variation in male age at maturity in both hatchery and wild environments.