It’s like a natural law or something.  He can’t go anywhere without stumbling onto a crime or racket in progress…  As Mark motors slowly toward the mainland (witness the skyline off his port bow…) He passes Marlin going the other way (I think, since there isn’t a skyline in the direction Marlin is going) with “those two guys” so yes, Mark, he left the island earlier and is now returning…

Mark has an interesting little grin on his face as he takes stock of the irony contained in a taxidermist turning down work… and so now the plot really begins.  No doubt he will start to put what few pieces there are together, probably talk to the loose-lipped guy at the boat rental operation (does Woods and Wildlife magazine pick up these expenses?) and well, the story continues to stagger out of the gates…