Just an observation I had, what are your thoughts?
You may be right on Penns, I'm not sure. I certainly think you're right on other streams. On many NC freestoners for example, the status quo is that the upper ends are cold and full of trout, and the lower ends warm and full of bass. Generally the largest trout are found in the transition region. I believe it's precisely because of what you are saying, there are very few coolwater refuges to oversummer, and larger trout dominate them. The rest of the year you have a largish stream with more food than fish. Hence, the few fish grow big easily.
Penns doesn't fit the mold easily, though. It doesn't fit many molds easily, so what else is new? There's a boatload of food, and if you just look at the # of fish/food ratio, it's actually underpopulated all the time. There are tons of biggish fish, but what it seems to lack is many true trophies (20+ inches). Not saying there's none, of course, but your chances of catching an 18 incher on Penns are FAR higher than on Spring Creek, for instance, and it ain't close. But your chances of catching a 23 incher is probably higher on Spring.
(we're talking truly wild fish, not counting the hogs that are stocked by various entities in either system)
So why does Penns grow so many approaching that 20" mark, and few over, whereas Spring grows relatively few large fish but those that do can get very large? I don't know. My guess was temps. I could be wrong. I've thought about other explanations. Maybe that Penns abundance of food is limited to bug life, which doesn't grow trophies like baitfish do? But Penns is pretty full of baitfish too, I'd say moreso than Spring, so strike that. Maybe Spring's fish migrate? But, we're talking above Bellefonte here, and there's that pesky dam that I don't think any fish are getting over. Harvest? Maybe from Poe to Coburn, but not in the C&R section. Pressure? No way, Spring gets way more pressure per acre of water.
Age? I think it's clear they grow quicker in Penns than in Spring, so if it's age it would mean that Spring Creek fish are capable of, at least on occasion, growing older (which I think is true). Why is what we're asking.
Maybe it's just because there are a lot of biggish fish? It's relatively easy for monsters to dominate a cold water refuge, or a prime feeding lie, when a bunch of dinks are around them. The commoners don't mess with the king. But maybe a little harder to dominate when there is an abundance of princes? Hence more substantial competition leads to less time on the throne?
