NEW ORLEANS — Aaron Jones made his way through the crowd to the foot of the stage, chin raised. An oyster shucking contest was under way, and the master of ceremonies was going around distributing oysters to audience members as if giving Communion, dropping one in Mr. Jones’s open mouth.

“Plump and salty,” Mr. Jones, 26, a hospitality major at the University of New Orleans, proclaimed after walking back to his girlfriend’s side with a big smile. Then, in a more somber moment, he said: “This may be the end of an era.”