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 Historical documents in the form of government correspondence and reports, explorers' accounts, and Hudson's Bay Fur Co. records yield further evidence.

 As background to the study, a brief history of the commercial fishery is outlined. Remote stations were scattered along the length of the Canadian border, and supported the fishing enterprises of the main towns: Sault Ste. Marie, Heron Bay, Port Coldwell, Jackfish, Rossport, Nipigon, Hurkett, and Thunder Bay.

The first commercial fisheries in Canadian waters were those operated by the Hudson Bay Company. Records are available from 1800 to the 1950s and contain many valuable entries concerning species composition, seasonal movements, spawning grounds, and spawning times. The relevance of these records to fisheries investigations prompted the inclusion in this review of notations of not only lake trout but of all fish species.

Fishermen tended to distinguish varieties of lake trout on the basis of the following criteria: 1. Spawning location and time, 2. Body weight and form, 3. Flesh colouration, 4. Skin colouration, and 5. Non-spawning movements.  

Fishermen distinguished four general variants of leans, fats or siscowets, halfbreeds, 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, racers, and deepwater leans. A form might have been quite site specific, spawning only on certain selected grounds or might, on the other hand, have composed a general spawning run of fish, appearing at many places along the shore or shoals. Each is discussed in turn, and local spawning habits, grounds, and movements are summarized by lake region. At least 250 former spawning grounds are identified, including 18 rivers which were once characterized by September runs of lake trout. Spawning locations for the deepwater, non-lean trout variants (paperbellies, half- breeds, and siscowet) are less easily discovered. Approximately 35 fishing grounds are noted, with spawning reported for at least four of these. Consideration is given to the possible existence of phenotypically distinct stocks of siscowet. Due to the nature of the sources used in an historical approach such as this, an abundance of clues for mapping former fish stocks are generated; unfortunately, many must also remain inconclusive.

Records collected during the course of this study are available at the Archives of Ontario, Toronto and the website https://northshorefisheries.net.