Motrout, I used to live in MO myself, and those Ozark trout are beauties. Ever fish Crane Creek or Capps Creek? Those are two of my favorites.
In fact, you make a good point. Crane Creek in SW MO was stocked with California redband rainbow trout once in the 1880s and never again since. It has been claimed that this pure strain of redband rainbow is one of only FOUR populations remaining on the planet that has not been hybridized with other strains of rainbows, and MDC jealously guards it as a no-kill, artificial lures (including flies) ONLY stream. In fact, just about every time I went fishing there, I was questioned by a large-statured Conservation officer with a semi-auto pistol on his hip. "You know that this stream is no kill, artificials only?" "Yes sir, that's EXACTLY why I'm here." I hooked and lost the biggest rainbow of my life there, a 20"+ hook-jawed male that looked like a steelhead and snapped me off in mid-air (I'll never forget that image as long as I live - I can still see the bright pink stripe on his side!).
The point being, yes, these fish are not native to that watershed, but they are now wild, self-sustaining, and perhaps even downright RARE. They certainly deserve protection. I freely admit that I love to catch brown trout, have caught them in plenty of places where other trout couldn't exist, and that I have probably caught more of them than any other trout species. Truth be known, the only places in my life I have EVER caught native trout are: brookies in northern lower MI and the U.P.; a few brookies on a trip to New Hampshire; a streambred redband rainbow (plus a PILE of stockers, with duller colors and less developed fins) in the Mackenzie River in OR; and coastal cutthroats in small coastal OR streams (did catch one small jack salmon out there on a worm as well). EVERYTHING else has been introduced at one time or another. I wouldn't have wanted those four experiences to be my ONLY trout catching adventures!
You also make a very valid point about affecting "non-target" species. As a biologist as well as a flyrodder, I appreciate ALL forms of life found in trout (and other) streams, and they are all there for a reason - in fact, it's often all the OTHER organisms that allow trout to live there in the first place!
Piscicides are a tool of last resort, as should be ANY kind of artificial chemical introduction into ANY natural ecosystem. However, I am certain that there are situations that justify their use, especially when the preservation of unique and nearly extinct trout subspecies are concerned. But use CAREFULLY!!!
Jonathon
P.S. Say HI to the Ozarks for me next time you go!
No matter how big the one you just caught is, there's always a bigger one out there somewhere...