Native Lake Trout (Salvelinus namaycush) Stocks in the Canadian Waters of Lake Superior Prior to 1955

Abstract

The decline of Lake Superior lake trout (Salvelinus namaycush) stocks after the sea lamprey (Petromyzon marinus) population explosion of the 1950s was both dramatic and decisive. Few native stocks remain to permit scientific data collection. However, interviews with old-time commercial fishermen suggest that there had existed many discrete or semi-discrete stocks within the lake. Historical documents in the form of government correspondence and reports, explorers' accounts, and Hudson's Bay Fur Co. records yield further evidence.Possible stocks are distinguished on the basis of anatomical features (including weight, body shape, and coloration) and behavioral differences (including seasonal movements and spawning habits). The relevance of these criteria for stock identification is discussed.Fishermen distinguished four general categories of S. namaycush: leans, fats or siscowets, half-breeds, and humpers or paperbellies. In addition, different "breeds" or forms of lean trout were commonly recognized. Often a form was known by a name referring to its most distinctive feature: blacks, redfins, yellowfins, grays, salmon-trout, red trout, moss trout, sand trout, and racers. These varieties are discussed and local spawning habits, grounds, and movements are summarized with maps, tables, and text. At least 200 former spawning grounds are identified, including 20 rivers which were once characterized by September runs of lake trout. Spawning locations for the deep-water, nonlean trout variants (paperbellies, half-breeds, and siscowets) are less easily discovered. Approximately 35 fishing grounds are noted, with spawning reported at 4 of these. Consideration is given to the possible existence of phenotypically distinct stocks of siscowet.Key words: lake trout, Salvelinus namaycush; stocks, anatomical features, behavioral differences