Mike,
I'll do my best to provide some background... Currently, "one of" PC's (Parks Canada's) mandates (though is seems to change with the direction of the wind) is to try to correct many mistakes of the past and reintroduce native species back into the mtn parks (bison, wolves, ws cutthroat). In the past, brook trout and Rainbows were purposely, sometimes illegally and sometimes by accident put into many mtn alpine lakes. In all circumstances where there were native fish (i.e., ws cutthroat and bull trout) the Brookies (and Rainbows) have pretty much whiped out their populations. There are circumstances where brook trout and rainbows have been "stocked" in lakes that were initially devoid of fish (as Shawn has mentioned). If you do a search ("Hidden Lake" & "Rainbow Lake") you will see some projects a few of us have been involved with where PC have recruited volunteer anglers to help rid (and catch brood stock) in specific systems while electro fishing and gill netting to rid these systems of these invasive/non-native species and reintroduced native ws cutthroat into these systems with a longterm goal of establishing self sustaining populations within the Bow Headwaters system entirely (a lofty goal for sure). Interesting to note, within the mtn parks, the only fish that you are albe to keep are these non-natives. YUM!!