The fisherman will be insulted by Lucifer's first offer and declare he has a family. He may require someone to smooth the situation over. If they're unwilling or unable to, they must find another fisherman and try a different tactic on their new target. Fortunately, there are many fishermen in the area.

Any fisherman they pick will want some proof of gold or silver. Wine, butter, or sugar will suffice, as well, since they're valuable staples for the fishermen. They can choose to pay him a small amount as a gesture of good faith, and promise him the rest.

Asking about the odd phenomenon, they'll discover that it's only occurred within the last 2-3 weeks.