Fish-N-

Actually, there is quite a lot of data that at least on some rivers, using hatcheries helps to rebuild stocks... at least for one generation. The important question that I see unresolved is that when the hatchery hatched fish come back and spawn in the river, do their progeny then have similar success as the others? That's really the important question from a genetic fitness standpoint.

On several streams and rivers in the OP, they have been doing broodstocking on summer chum. All of the rivers and streams have shown impressive returns coincident with the program.

I think that some major differences in the life histories between summer chum and chinook might make the same kind of program more challenging for chinook, though.