Vary retrieval speeds to find what triggers the most strikes. To troll, use the same techniques and fish the same structure as you would for walleye. Use a lure that dives close to the bottom. Look for bars or ridges in the river bottom, and ledges by islands. Troll at 2-3 miles per hour and downstream, but experiment to find what works best for a particular location or day.
Many anglers have better results with higher speeds and sometimes with trolling upstream.