I've seen the exact same pattern regarding trout. Used to catch a decent number of quality fish as far down river as star brick. No longer. Never used to catch many smallmouth above the warren bridge. That's changed as well. I don't have temperature records and haven't looked at the usgs data but I think weather has had some impact. Recent summer water temperatures reach the 70s sooner in June. Used to take until August. Stocking has also changed but those were mostly if not all rainbows. Browns came from reproducing fish in tribs.