the seals aren't that new to the area. I've got pics of the group from more than ten years ago. They tended to haul out on the island off Spermaceti Cove, that's no longer an island.
They are only seasonal visitors and there's plenty of clams, crabs, and fish for them to eat, and although I'm not a marine mammal expert nor have I studied their feces, they probably are not limiting any resources.
They also haul out on the islands off Staten Island, in NY Harbor, but we don't get to stare at them there.
I may have had one take an eel from me while fishing once(fall or spring), but there's no pic so it didn't happen.
