dude,
As long as the friend payed for the trip and the jackpot, I have no problem with it. The question comes in if the friend didn't pay for the trip. That would not classify that person as a customer and as I understand it, only customers are eligable for the jackpot. On the other side, if you know a deckhand or somethin like that and he sneaks you on the boat for no cost, would that mean you're not eligable for the jackpot? It's a tough call. You are fishing like everyone else, but you didn't pay to get on. I think it's one of those deals where it's a situational decision. As long as the deckhand isn't hooking fish and handing them off to his girlfriend for the jackpot... If there's no major problem like that, I'd let it slide. I've never heard of sheephead not counting for the jp. I've won the jp with a sheephead on the stardust before. The fish that don't count in sb are sharks, rays and skates.
-Brian