Marty,
Sorry if my original post was confusing. The question I was asking was far more simple than I made it: do you tend to find native fish in the same lower-river holding water, late in the season, as you find hatchery fish early in the season? The person with whom I had the original conversation--a long time ago now--claimed that natives run right through the lower holding water, and that even if there was an equally large native run, there would be fewer fish in the lower river at the height of that run than there were at the peak of the hatchery run. His claim was that this resulted from a propensity of natives to head straight upstream--an impluse hatchery fish allegedly didn't share.
Perhaps there's a better way to ask this: do you drift the same water late season as you do early season? If not, why not? You indicated that you've caught some natives on the Nestucca already--I have too--but I'm sure you'd agree the bulk of the natives won't be here for a while still. Do they, in your opinion, keg-up in the lower river like the hatchery fish, or do they tend to run upstream more quickly?
I hadn't thought about it until recently, but if the original premise were correct, it would be a pretty significant behavioral difference. That or I should just go fishing!