I think the real problem with Chambers fish was the return time. I tend to agree with Jeff Cederholm's idea that the early fish went up the tribs and the later fish spawned in mainstems. Even with reproductively incompetent Chambers fish, their very presence resulted in by catch of wilds. Since it is not possible in PS to fish selectively for steelhead, the presence of Chambers fish removes that component.

Saw spawner survey data from the Green and Skagit. My look ended about a decade ago but the Green lost a whole lot of trib spawning and the Skagit some. This actually does fit well with the observation that calculations show that MSY escapement goals for many PS steelhead should be lowered. If you remove a big chunk of the rearing population (they don't redistribute too far up tribs) and the remaining mainstem spawners are most of what is left then the goal can, justifiably, go down.