Phys.org reports that farmers were transporting live fish to stock mountain lakes in the Pyrenees much earlier than previously thought. High mountain lakes are often historically fishless due to natural barriers created by glaciers, as was the case with Lake Redon in northeastern Spain. The 240-foot-deep lake is isolated from fluvial waterways by a 330-foot waterfall, which makes it impossible for fish to naturally enter and colonize it. However, there are an estimated 60,000 brown trout living in it today. Historic documents record that the process of fish stocking was begun by at least the fourteenth or fifteenth century. Recent...