I've heard rumors of stripers getting up to the spillway, but I can't claim more than that. There's something down there that can empty spools, but what that something is? No idea. Could be stripers I guess. White bass? I'd guess a misidentified white perch. Then again, since they opened up the creek all the way down to the bay, who knows what could wander up?
Give Neary's a call on Friday. They should know what's in the lake better than anyone.
Octoraro feeds directly into the Susky, just below the pool at Conowingo. That part of the river is loaded with dink and schoolie sized stripers all season. It is littered with them right now. I can almost guarantee that any caught in the Octorara creek (below the lake at least) are fish that have swum up from the Susky. It is really not all that far. I have caught smaller sized ones far up stream in some Delco trout streams that feed into the Delaware. Same thing.