Sorry, but there's nothing about cod in the song. It's about a fisherman, but just tells of the death of his fisherman father during a storm, and the stars which guide all sailors. Also, the poverty of his mother, as he's her only support.
Very sweet little song, and rather sad.
If you type in ' Lyrics 'Partons, le mer est belle' on Google, you can see all the verses and chorus in French there.