I hesitate to post this, but I'm going to anyway. Last Saturday at right around dusk I was sitting on my bulkhead in MA 13 watching the fry foraging around my floating dock. There were thousands of them actively feeding, the school was very large running from 5 ft from shore out to probably 20 ft from shore. I've never seen that many in one large school like that. I am confident that they were chum fry, and I made a point of walking out on the dock earlier in the day to verify it because I'd never seen that many in such a large school like that. I didn't catch any to key out, but as a biologist I was satisfied with my casual identification as chum. There were a few larger fish working around them and keeping them together in a large school. As I sat there in the twilight all of a sudden there was a very large wake on the surface of the water running toward the shore. The water parted like it does with the bow of a boat but I couldn't see what caused it, just the wake and what appeared to be a lunge forward by something to scoop up some of the chum fry. Then it dissappeared. I figured it must have been a very large sea lion, but it was in really close to shore and there was no sea lion surfacing to breathe like you normally see and hear when they are around. So I sat there wondering what it was for 10 minutes or so. Then it happened again. This time I could see a shadow of the front of something very large just above the surface of the water, but it was getting dark and I couldn't make a positive ID. The wake was large enough this time that it rocked my dock back and forth like a medium size boat wake does. Definitely had a very large body to make that kind of wake. After another 15 minutes it was getting very dark and I stood up to head inside. Then it happened again, but I couldn't see anything - just the sound of the water and then the waves hitting the dock. No sign of seals or sea lions around, too big for anything but the largest sea lion anyway. It was dead quiet, and I am sure would have heard any seals around surface to breathe. So all I can figure is that it must have been a large 6 gill shark, which are found in the area fairly frequently from May through July when they breed in the s sound. Further internet investigation has me convinced that this is what it must have been, but I have no pictures and no proof of it. There was a 14 ft long 6 gill found on the beach less than a mile away a couple years ago, so it isn't out of the question.