How does the old man attach the marlin to the skiff?

Santiago lashes its body alongside his skiff. The fish is too heavy to put in the boat itself, so he must tow it back to shore alongside the boat. He pulls a line through the marlin's gills and out its mouth, keeping its head near the bow. "I want to see him, he thought, and to touch and to feel him. He is my fortune, he thought" (95). Having secured the marlin to the skiff, Santiago draws the sail and lets the trade wind push him toward the southwest.