"What? ... What I long for, mate, is a ship. My ship, more precisely. That's a problem to be sorted out soon enough." There's a second where Jack actually thinks about the selkie's words, but he shakes the concern quickly from his mind. He's never been much troubled by anyone's loss. Not since he was a child. Why would that change now? Ridiculous.
Jack sighs and hangs his head as the selkie apologizes to him. It figures. But what to do with the thing now? He may have been working to scare the creature and keep it from running when he told the selkie Tortuga was dangerous for the seal to travel alone, but it's still very true. Now Jack is left empty handed and with this animal's life on his conscience.
"Bugger. I knew it. ... Way I see it, you still owe me, then, do you not? You spoke with the flippery little merwenches, yes? What else can you speak with? If you can not save me having t'die, then perhaps you'll help me find one that can. Then I'll see to dropping you off in safer and cooler waters. Do we have an accord? Or would you rather take your chances all to your onesies? hmm?"