It is pretty well established that even at one generation, time spent in a hatchery can have deleterious effects. Any organism responds to its environment. In a hatchery, 95% of the eggs are converted to fry while in the wild 20% is often high. At a very simple level, that means something like 4 out of every 5 hatchery fry would not have emerged in the wild. Those genes are protected and in succeeding generations may come to dominate. You raise those fish in 50 degree hatchery water and they won't do well in 35 degree creeks. We see this, and it is why when they get loose to spawn in the wild you get not much from it.

But, those genes, if deleterious, are weeded out in a hurry. But, to permanently keep them out you have to stop letting them get into the gravel. Then, what does spawn will adapt, and rather quickly. But, if you keep on allowing a few hundred of them to spawn, you keep getting a few hundred, plus maybe a few more, back.

I believe that the idea of allowing fish spawning in the wild to naturally adapt to that system is very workable IF you stop allowing hatchery fish to spawn out there and IF you significantly increase escapement numbers (by 10-20X in at least the short term). Then, the fish will sort it out.

We don't really need ESA for WA salmon. We (WA Co-managers) control most of the harvest, we (WA State) control land use, we (WA state) control the water removals and discharges.