
I agree with Cliff that the DWR prefers their trout over Bass.
First, is tradition. Utah has been managed as a cold water fishery for most of our lives, I remember when i was a kid and the "Trash" fish started to appear in Pineview. I thought it was the end of the world after listening to all the grown ups complain about it.
Second, is is the priority of the fish and game to try to make people happy. The easiest way to make most people happy is to catch some fish when they go fishing. The easiest way to keep them happy is to dump a load of fish in the lake, and tell people to fill up their stringers.
Third, DWR trout hatcheries employee many of their own people. They have no desire to see those folks lose their jobs, or have their budgets cut because they don't need fish to dump into the lakes.
With that said, I agree with Cliff, Utah DWR does have a vested and financial interest in trout.
Sure, it would make a lot of sense to create a self sustaining eco-system in our lakes, using natural preadators like bass and walleye to control the chubs and carp, planting trout that are not sterile, (yes, they do plant sterile trout, if you wonder why refer back to the third reason), and letting the fish in our lakes reproduce and be managed by the anglers, using possession limits to manage fish numbers so we don't need to rely on hatchery fish. Yes, maybe we wouldn't be able to keep any fish on some lakes and other lakes may have a twenty fish limit one year and a two fish limit the next but it would provide a quality experience to all, and be a whole like cheaper than raising fish for a few years just to poison them all later.