For the most part, the anadromous fish in the mainstem Yak spawn in the upper watershed, above Roza Dam. What you're advocating, gdm43, is annihilating these runs of fish, some of them wild. So far there isn't much data that I've seen indicating that recovered salmon populations will harm the trout fishery. Lots of talk among non-biologists, but little evidence.Keep the salmon /steelhead below Roza Dam and keep the waters above the dam for trout.
I talked to a fisheries guy this spring who had an interesting tidbit that was news to me: that we're mostly catching native 'bows in the Yak. He said despite all the years of misguided stocking, the present fish are not, by and large, mutts. Which makes sense when you consider the reproductive capacities of stocked fish. The natives held on through all this insult, and now, given a chance, they're proving nature's wisdom. I think this also helps explain why a 12" Yakima rainbow has so much fight in it.
As for the quality of the Yak itself, well it just seems to be getting better in the 11 years that I've fished it, mainly due to the instituting of C&R regs I'd guess. It's not Montana, but the numbers are going up, especially based on those 2001 counts. I found a bunch of online archived WDFW counts from the '90s, and the numbers were more in the 600-800 range per mile. So that's good news. My personal experience is that the last few years I've caught more fish, but this year they were on average smaller than last year. Bottom line: Like any worthwhile stream, you need to learn it.