Another thing to remember about fish, especially those runs exposed to high harvest rates, is they spawn (or get their eggs taken) because they weren't caught.

If you put a 20-30% total exploitation on a run, most of what spawns was obviously not caught, but a lot of "dumber" ones made it to the grounds. You take 90-95% (nice hatchery run) and almost every fish was not on'y exposed to fishing but survived. By not biting, by not pausing on the way up, by coming in when the seasons were closed.

And we are changing the rain patterns. I took a look once at rainfall in the Cedar River watershed with a break, I think, as pre and post 1980. The rainfall over September-December was the same but as I recall September and October were much drier and November much wetter. Changes how the fish respond.