The stink is a pretty good start! That is a gizzard shad, or locally mud shad, which is kinda what I thought when I heard there were shad at the dam this early. Years ago, before 9/11 they would be so thick in there you would snag dozens of them in the fall while fishing at night for walleye.
http://dnr.maryland.gov/Fisheries/Pages/fishfacts-index.aspx
A story for you. I was fishing up there at the base of the dam one night in the fall and it was so cold that I was the only one out there fishing (read as dumb enough to be out there fishing). I happened to look down river and there was a huge raccoon coming up the shore line straight for me. I didn't really think too much about it until he got within less than ten feet of me and I decided that was plenty close enough. I kicked a bunch of rocks at it and it ran back into the boulders. Well, I went on fishing and pretty much forgot about the raccoon. About every two or three casts, I would snag a mud shad but fortunately, most of them came off before I got them out of the water-which was absolutely all right with me. Well, I finally had one that stayed on long enough to get it out to where it was laying on the gravel in the wash before it came unhooked. I thought to myself, I'll kick that dude up on shore and the raccoon will get him when I leave. So, I flipped him up on the bank a couple of feet behind me with my foot. No sooner had it hit the ground than the **** was all over it. It grabbed the mud shad and made a bee line back into the boulders. I have often wondered if that was a once in a lifetime occurrence or if that blamed **** had learned to lie in wait for a free meal. Had that been a walleye, I might have had to fight him for it, but ***** are pretty tough customers in a scrap. But there again, I really do like walleyes!! I had to quit fishing soon after that because the guides on my rod kept freezing up so bad that I couldn't even cast.