Parasites from 'Alien Shores': The Decline of Canada's Freshwater Fishing Industry

After 1900, the Northwest fishing industry expanded substantially from southern Manitoba to the Northwest Territories, with production directed principally to American urban markets. In response to the economic crisis of the 1930s, new international trade regulations prohibited the importation of fish infected with the Triaenophorus parasite and included two of the most important commercial freshwater fish species: tullibee and lake whitefish. In the following decades, in spite of repeated state and scientific interventions in the fishery, Canada's freshwater fishing industry was unable to fully recover from the economic impacts of the new trade regulations. This failure reflected the unprecedented influence of the parasite and its ecological relationships to other species and the freshwaters in which it was found. This paper goes beyond a conventional narrative of the impacts of economic protectionism to ascertain how the natural context in which resources such as fish are found intervenes in human socio-economic affairs.