The fish has to survive being caught. If a Chinook has the genetics to mature at age-7, as they used to, what chance does it have to live that long in the face of all the marine fisheries?

We have known for decades that age at maturity had a strong genetic component. WDG tried to take advantage of this with Skamania Summers. They bred the bigger, older fish with each other and got significantly larger adults back. Just too few, due to the increased at-sea losses, to sustain the program.

If you want the largest fish to return you have to not kill them before they do. Which means you fish in the bays and rivers after they stopped most feeding.