It’s 3 a.m. and the beach in El Bosque, in southeast Mexico, is humming with small talk and laughter as Viviana Velázquez eases out of her hammock and dashes to the shoreline to greet a boat returning with the night’s catch. Velázquez, 38, and her 13-year-old daughter, Marlene, help the tired fishermen unload the ice boxes and heave a plastic crate full of bonito to the cooperative to be weighed. The captain pays Velázquez for her help in fish. …