Great find, actually I've really enjoyed going back and looking at some of your finds from that incredible site you hunt, but I don't think it's a fish hook... I have no doubt that it's an authentic hook, but I don't think it was used to catch fish.
A couple of years back, some collectors and a knapper tried making and fishing with stone fish hooks. Big, little, thin, fat, knapped, hardstone, ground and polished flint, burlington, flintridge, edwards, etc. stone, slate, etc. None of us could land a fish. (For those of you who like fishing, try it some time.)
The first problem was finding a way to bait the hook. Worms were out of the question, chunks of beef worked, as did dough balls and 3 inch blue gills, but really any movement and the bait came off the hook.
The second problem, was that we found that fish couldn't bit the hook hard enough to hook their jaws and it wasn't sharp enough to hook them in the gullet if swallowed whole. As example try taking that hook (or a modern stone hook) and pressing hard with your finger. You'll dent the skin, but you probably won't cut and penetrate unless you saw back and forth. As many of us have seen or felt, if you accidentally do the same thing with a metal fish hook it'll slide right through with very little pressure. I went to a pond in Indiana that is jammed with carp (you spit in the water and the fish jump to get it.) I couldn't hook a single fish (they took the bait, but I couldn't hook them.) One of the guys in Kentucky let the hook soak over night with a chunk of meat and managed to hook what he thought was a large catfish on a fairly thin hook, but the hook snapped as he was trying to pull it up.
The neat part was that a couple of the guys tried with bone hooks, and managed to land small fish (if the hook was very fresh bone, they didn't even need bait.)
