The thing I learned about fish being around hatcheries over the years is that decisions have a real and nearly immediate effect on the creature. Culture decisions normally isolate this to the hatchery production ( dependent on straying ) but harvest effects both W & H. It just takes much longer to show in the natural production.

Been away from the game a bit Tug but they did move to take eggs from the full run spectrum rather than a certain timing or using run compression. The early timed hatchery Coho on the Satsop came from taking the eggtake from the front of the run only compressing the return timing window. You end up with a fish that is inclined to return early rather than over eight weeks.