jd, that container vessel may have been light loaded because the draft at port of Newark is too low for that class of ship.
That's been an issue for many years there, as dredging brings up all kinds of environmental issues.
Maersk operates some of the largest vessels in the world. If that is a post-panamax vessel in their global service, it may hold as many as 7,500 40' containers. The draft required for that ship is something like 45-feet if fully loaded. Newark is probably only about 40 feet if I recall correctly, so they either have to off-load a bunch at Halifax, carry some empties, or a little of both to get in clean at Newark.
Furthermore, due to the higher price of fuel and water shipping many of the containers formerly going all-water to the east coast from Asia may be coming in through the west coast.