GALLIANO - They're killed by the thousands every year, their carcasses buried in the marsh. Their furry pelts, once sheared, dyed, made into coats and hats and sold on the international market, are now worth so little that some say it's more economical to cast them aside to rot. Nutria were imported to Louisiana from South America in the 1930s to supply a booming American fur industry. But they soon escaped into the wetlands where their population and their appetite for marsh-saving grasses exploded. Decades ago, their numbers were controlled by the hunters and trappers who worked the marshlands of...