Though not obvious from this range, the bird picking at the fish is a juvenile Lesser Black-backed Gull. There were 4 Lesser Black-backs on this little island today, with 2 adults and a 2nd-winter in addition to this bird. The older birds stand our readily with their much darker mantles compared to Ringers and Herrings, but young birds aren't as distinctive.

Details are hard to get in these shots (taken from the bridge at Paris Landing; a long way off for my set-up), but notice the very slim and elongated look of the Lesser Black-back. The tertials are completely dark in the center, with only light edging, and also notice the dark bar on the lower edge of the wing formed by the greater coverts.