Your english is very adequate,,, better than many Americans that I have encountered. If I were you, I would be getting some minnow traps and doing some fish sampling in creeks, beaver ponds, and in smaller local lakes around the shoreline. Bait traps with dry pet food or sale bread. Run them every day or two.
My Fishes of Canada book indicates the distribution range of bluntnose minnows and fathead minnows extends into the southwest section of Quebec, maybe slightly further NE into the province. IF you are in central Quebec then these minnows may not be in your area.
http://fishesofboneyardcreek.weebly.com/bluntnose-minnow.html If you are able to catch any smaller fish we can help identify them to see if they are stream or pond spawners. You are looking for pond spawners. Add then to your small pond and monitor what becomes common due to reproduction to learn what is spawning in the pond. If the provincial officials give you a problem tell them the darn fish eating birds must have stocked your ponds. As long as your fish are caught locally you should have no illegal issues.
My guess is the small lakes and ponds in your are have to have local native minnows that spawn in beaver pools, ponds, and lakes. Something in the minnow forage type of food has be able to spawn in static water of Quebec to provide small fish to feed the larger fish other than big fish eating only little sport-game fish. Small dace with very fine scales are a common far northern fish, some are capable of pond spawning.
Transferring smaller YP to the main ponds works. If all sizes of perch in the main pond with SMbass are scarce, then it is likely you have too many predators eating too many small perch. Selectively harvest predators until the overall perch numbers and their catchability in the main pond increases after a few years. Larger perch should be able to thrive and be harvested in the big pond if bass are not over abundant. If you are not seeing very many large perch then remove more bass. Fish need to be regularly harvested and monitored to have a viable quality fishery.
Your locally collected Crayfish are good for your needs. Provide them lots of good rocky habitat and they should survive if there is not excessive predation by your bass walleye. Crayfish in your little pond will keep the algae and delicate plants low to absent. Crayfish like to eat algae. Crayfish should thrive in your small pond with spawning minnows & some perch. Both can be transferred to the big pond.
Return often to keep us updated about your pond progress in Quebec.