You can use them on private lakes. PM sent.
I wonder if you can use it on a non-navigable creek running through private property? It isn't public water if you can't get to it by boat, but I'm not sure what rights the state claims in that situation.
I once saw a state fisheries boat shocking and netting stripers, presumably for brood fish. I didn't get to talk to them, but I don't know why else they would have been trying to catch and keep alive 20 pound plus fish. They were using a generator to shock them, so that was a lot more electricity than a device like the OP has. It doesn't take much to knock a catfish to the surface, and that's the reason that the old telephones would work. It takes a lot more power to get a scaly fish up. At least, that's what people have told me. I have no personal experience with it.