Shipments of coal on U.S.-flag vessels working in the Great Lakes totaled 25,347,709 tons in 2012, a decrease of 8.2 percent compared to 2011. The trade was 25 percent off its 5-year average, according to the Lake Carrier’s Association (LCA), which represents 17 American companies that operate 57 U.S.-flag vessels on the Great Lakes. Shipments from Lake Superior ports - 15.1 million tons - were just about even with 2011. Included in that total were 1.3 million tons shi...