Sailors are just very superstitous, fishermen even more so.
When even staying alive is so uncertain people look to such things. My dad was a mechanic in the RAF during WWll and from what he said the pilots, aircrews and even the ground staff were very superstitous too.

I don't know why the poor little long ears is suposed to be so unlucky - a fisherman would turn around and go home if he happened to see one on the way to his boat, because he 'knew' it was an omen of disaster. It goes back a long way, maybe back to when it was believed that witches could turn themselves into hares?

Anne