Dave -
Regarding the fate of those legal rainbows planted in rivers.

Soem 50 years ago there was several studies look at that issue; some of which was done in Montana. Basically what was found was that shortly after the fish were released (within weeks) the vast majority of the uncaught fish just disappeared never to be seen again. They either eaten by predators were failed to adapt to a natural situation and either starved to death or were washed downstream.

What the folks in Montana found was while the hatchery trout were in the river they tended to push out the wild fish and once the hatchery fish were caught or disappeared there were less trout in the system than before the fish were released. This of course was why they went to wild trout management.

It took States like Washington much longer time to end those programs, mostly because of the political popularity of such programs. That was compound of course by the fact the various PUDs and other used the planting of those fish as part of their mitigation packages.

One interesting side note from those stream catchable plants is that they seem to have left little genetic foot print on our local populations. Virtually all the rainbows used in those programs were from brood stocks that had long histories of domestication and were genetically very different than the native rainbow/steelhead stocks. I recall in one case where the genetic profile of the Cedar River steelhead/rainbow trout was examined. For a couple of decades (late 1940s into the 1960s) 10,000s of catchable hatchery rainbows were released into the Cedar yet 30 some years later there was little or no evidence of those fish successfully interaction with the native stocks.

Tight lines
Curt