Great Lakes are estimated at 900 trillion. The influx of parasitic lamprey populations after the development of the Erie Canal and the much later Welland Canal led to the two federal governments of the US and Canada working on joint proposals to control it. By the mid-1950s, the lake trout populations of Lakes Michigan and Huron were reduced, with the lamprey deemed largely to blame. This led to the launch of the bi-national Great Lakes Fishery Commission. "The Great Lakes: An Environmental Atlas and Resource Book" (1972) noted: "Only pockets remain of the once large commercial fishery." But, water quality improvements realized
History of the British canal system Telford, whose Ellesmere Canal helped link the Severn and the Mersey. The bulk of the canal system was built in the industrial Midlands and the north of England, where navigable rivers most needed extending and connecting, and heavy cargoes of manufactured goods, raw materials or coal most needed carrying. Most of the traffic on the canal network was internal. However, the network linked with coastal port cities such as London, Liverpool, and Bristol, where cargo could be exchanged with seagoing ships for import and export. The North West and West Midlands regions contain a dense network of canals. The great