The problem with both the Grand and the Conestogo Rivers as far as natural reproduction goes is timing. Brown trout spawn in the fall. They dig redds and deposit their eggs under gravel. The Conestogo is a tail water fishery dependent on bottom draw from the lake above for its cold water. Now in natural cold water fisheries they rely on springs for their water source. During the winter that "Cold" water is actually warm keeping the creek or stream ice free and giving the eggs a steady supply of well oxygenated water. In the Conestogo the water get quite cold in the river and a lot of the redds develop anchor ice. This prevents oxygenated water from getting to the eggs and they suffocate and become nonviable. Now the next problem, those redds that survive the winter are subject to extreme flooding in the spring before the eggs are ready to hatch. The majority of redds that survived the anchor ice are destroyed and swept away. We found this out the hard way on the Grand when in our second year we created an artificial spawning channel and filled it with perfect gravel. The browns used it heavily that fall and there were redds everywhere. As soon as spring levels returned to normal an inspection of the channel revealed NO gravel to be found. Unfortunately gravel that is good for spawning just wont hold its place in the rivers due to the extreme force of the spring dam release. Now the few redds that have remained viable have survived anchor ice and super high water levels face one last danger which seems to end any chance of survival. As the water levels drop all the suspended solids of clay and sand drift down onto them. These are called fines. The fines bury the last of the redds suffocating the eggs weeks before they have had a chance to hatch. There is some natural reproduction in the Grand thanks to Carrol and Swan Creeks which are both trout stream tributaries that enter below the Gorge. The rainbows that still exist in the Grand in the trout stretch due a much better job of natural production than the browns because they face none of these issues. As for the fish you have caught I believe they are fish that just didn't get clipped. It happens a lot particularly when doing a large batch of fish. Young of the year fish from this year would be well under 5 inches and fish that have survived for at least one winter would be 13" or better. Don't get me wrong it a great fishery but its essentially a put and take fishery without the take.