I became a believer in fishing small jigs and jig-flies for Steelhead and Great Lakes Brown Trout many years ago after fishing the Upper NY Lake Ontario and Lake Erie tributaries and experiencing outproducing both species by fishing jigs and jig-flies over roe bags.
When both species are in the lower sections of tributaries, like the first deep, moving water pools, they seem to work especially well. I have caught lots of fresh-run and also dark fish using the same jigs and jig-flies. Later when the regular trout seasons opens and steelhead are further up-stream and holding in shallower water, roe bags and imitation eggs and traditional flies work best.
I think the main reason Steelhead and Great Lakes Brown trout take jigs and jig-flies so well right after they enter the tributaries is because they are so strongly imprinted with striking anything that looks like the shape or silhouette of a baitfish . This makes sense since they were constantly feeding in the open Great Lakes just before starting their spawning run.
Conner Grdosic has discovered how well jigs and jig-flies work, especially in the Niagara River and especially in late winter early spring when there are no salmon eggs flowing with the current. The jig and jig-flies can be dead-drifted just like a roe bag, or you can regularly “twitch” the float to make the jig and jig-fly have an even more tantalizing action. How well can they work? Conner was 3 for 6 just the other day on his hand tied jigs!!