One thing I observed at the presentations at the Pacific Coast Steelhead Management meetings (but it was a decade ago) was that the only really successful hatchery programs were the huge ones. The piddly-assed 10-20-30K plantings returned next to nothing. It was the 200-300-500K stockings that supported fisheries. As I recall, when I asked, nobody was looking into why it took the larger programs to be successful. I suspected then, and still do now, that the smaller programs were supported by so few spawners that genetic issues were easy to have.