Ottawa:
Here in Buffalo, New York area along Lake Erie, and the back bays, and creeks, we use small Lake Minnows, similar to those found in your Lake Simcoe area.
To hook those tasty morsels, you need small hooks and small baits. Sometimes cutting or breaking a minnow in two will help considerably. Did you know that Smelt will follow your line upwards towards the open hole if you go slow!. In this case you would hold a school right under your hole, and no need to drop down to heavy depths. We do catch Smelt in Lake Erie in water over 60ft, usually while Perch fishing. Our Smelt like to hold on, and usually their bite is so lite, unless you are watching the pole, you won';t see the tiny taps they make. A slow steady line retrive in deep water will help you to land them when hooked.
Here in Lake Erie, our smelt are even found anywhere even in 4ft or less water around boat docks in harbors. Maybe you can try different depths to locate them.
It is not unusual to smelt fish here with two small hooks, size 10 long shank(best ) and get two at a time each time you drop in. In the harbors, in shallow water you sight fish them.A slight jigging action, then a rest usually tricks them into biting. Our smelt here tend to bite from side to side, vrs up and down.
Wish I could help more!
Bear_Lake_Bob
Fredonia, New York