Editor’s Note: Reporting for this article was made possible by the Guerry Beam Memorial Reporting Grant award from the Institute for Journalism and Natural Resources. On a sunny, 85-degree day in August, some 9,300 oysters were loaded into ice-filled containers on southern Maine’s Casco Bay. The boat shuttling them from the warm, shallow waters of Recompense Cove to the marina two miles away hummed quietly.