and if you see the "dots" they haw symbol in it , it's for sea traffic(routs) that part are heavy traffic from Norway, Denmark Sweden Finland and more
So your "DOTS" are simple marks of the way the ship shall do and anchor pases and so on and oficous as
Well, if Vessel tracker would cover all Europe & not just some ports & straits - then all screen will be with "dots"
So here you haw the explanation of you pick AA