Were these trout stocked in this lake?
Due to the large majority of trout in PA being stocked, I have on occasion targeted them through the ice. I have noticed on this trips, that stocked trout (maybe all trout, I don't know) tend to cruise in the 1-3' range below the surface of the ice. I use a fish finder when I ice fish, and the number of fish that passed through this layer of the lake(s) was astounding. I look down the hole, watch for 20 minutes, and see anywhere from 3 to 4 fish cruise by in that time frame. I've never seen anything like it with any other fish species I've ice fished for.