Here's a simplified thought about what is going on. The fish evolved a behavior pattern that allowed them to be successful. It may have been to get out of the ocean, hold for freshet, the bolt. Whatever.
Over the decades we remove them. What spawns is what survives. There are wild coho in PS that are now spawning in December/January and later. Why? because their parents did.
For a long time I scoffed at the the idea that hatcheries, especially, bred non-biters. Again, if you harvest 90% of the run, and much/most is with hook and line just what does live?
Basically, what spawns is what doesn't get caught.