From the very first Batman #9, way, way back. It's not Captain Ahab but it might as well be. There is no actual mention of the name "Moby Dick" but who else could it be? This is clearly an homage to the novel. Batman even rides the back of a whale! They even show, quite well too, what happens to a whale once they harpoon it. Batman killed the whale. Just an interesting little footnote to Moby Dick lore. A story explicitly for kids of the time, and they probably understood the references to the novel. That's also why I am a little surprised that there is no mention of the book. I sort of expected Robin to say something at the end like he was going to read the book now, and maybe the kids at home should go read it too.