Wooly bugger, marabou and bunny leeches, muddler minnows, zonkers, and large smolt patterns. Fish these off a sink-tip line, type III or IV depending on the water. Try dead drifting, striping, and swinging.

Oh, and glad to hear that you are releasing them. All bull trout/dollies should be released regardless of what some people think. They really don't eat that many salmon smolts (studies have shown that large coho smolts eat more salmon smolts). Large populations of these fish mean that the river is "healthy" and able to support many large fish. Also they grow real slowly and have low spawning rates.