I imagine this bug has been reported already, but just in case:
The shark is clipping into the raft when he attacks and is able to attack random spots in the center. I had all of my equipment in the center of my 12x12 raft, and he was able to clip into the middle and destroy the foundation that one of my storage chests was sitting on. Then later he attacked one of my collection nets, which was surrounded on all sides by foundation.