As soon as the crewman comes down into the hold, Jack smiles and steps back from the bars to wait to be released. The blood is noted. A bit of a good sign, if a morbid one. Once the cell door is open, Jack walks out proudly, dusts himself off and straightens his hat.
He looks in at the selkie. "I will let you out, but you must do as I say or we'll both end up locked away again or worse. You speak their language. I need you to translate for me. Once we've set sail, you can sleep in the captain's bed and won't have to return here."
Jack gestures for the sailor to unlock the selkie's cell door. "Let 'im out."
The man's a little hesitant, but finally opens the door to the selkie's cell.
"Good. Now, selkie? I'll need you t'help me on deck. I'll not let a one of them touch you. That's not t'be your job here."