I surprised that you never got onto the shad fishing on the Delaware River, they are a big deal there and I often thought on a trip there when I lived in N. C. PA. I do know that I have eaten them and they are very tasty fish especially smoked.
Flounder are fun to catch and very much fun to eat. I caught my first on the Eastern Shore of VA. and my last right here in Cook Inlet at the mouth of the Kenai River; very fun to eat. I've also caught small Halibut on flies, for flounder you just let the fly rest on the bottom and make small strips of the line to find the strike. For Atlantic Salmon you are at least on the right coast for it
Some travel is definitely in your future, it'll be a drive but if you go down to Bangor and take Rt. 9 over to Calais you'll be right at the border. Then it's a beautiful trip over to places with names like Miramichi & Margaree. It's been quite a few years (1985, 86, & 87) but I can remember those places like last summer. It sounds like you've got it right at your door but whenever you get the traveling druthers there are plenty of options. I could go on and on, I had often considered relocating to Maine myself.