I thought most grain barges had covers on them. Not sure how the bear would a) get onboard except via gangway, b) get inside the hopper without anybody seeing them, and c) get back out of the hopper?
If true, how would you like to be the deckhand that discovered that stowaway? Making rounds at night checking lashings and nav lights and see this big 250 lb shape with glowing eyes staring back out at you? While out in the middle of the open water?
I've had a few encounters including one that came up a trail toward me when backpacking roughly 2 miles from my car and with no one else around. It ran off when I yelled at it but if it were in a different mood...that's a pretty helpless feeling.