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

Abstract

Institute for Environanenlal Studies, Universiy of Toronto, Toronto, Ont. M5S dA4 GOODIER, 4. L. 1981. Native lake trout (Salvebinus namaycush) stocks in the Canadian waters of Lake Superior prior to 1955. Can. J. Fish. Aquat. Sci. 38: 1424-1734.The decline of Lake Superior lake trout (Salvelinus namaycezsh) stocks after the sea lamprey (Petromyzan marinus) population expIosion 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 semidiscrete stocks within the lake. Historical documents in the form of government correspondence and reports, explorers' accounts, and Hudson's Bay Fur Co. records yield fuflher evidence.Possible stocks are distinguished on the basis sf 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 . narmaycush: leans, fats or siscowets, half-breeds, md humpers or paperbellies. In addition, different ""reeds" 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 sf 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.

A genetic basis for the phenotypic differentiation between siscowet and lean lake trout (Salvelinus namaycush)

“…Similarly, various lake trout forms have been reported in the Laurentian Great Lakes (Agassiz 1850; Brown et al. 1981; Goodier 1981) and more recently from large Canadian shield lakes (Blackie et al. 2003; Alfonso 2004; Zimmerman et al.…”

Differentiation of deep-water lake charr Salvelinus namaycush in North American lakes

“…Distinctive shallowwater morphs of lake charr have been described for Great Bear Lake (Blackie et al 2003;Alfonso 2004) and have been reported from the Great Lakes (Brown et al 1981;Goodier 1981;Krueger and Ihssen 1995), but enough descriptive material for across-lake comparisons is lacking. The problem is with the Laurentian Great Lakes accounts, which except for the lean morph are sparse, consisting mostly of comments on color variations and generalized descriptions of shape (e.g., racers) (Goodier 1981). Therefore, I will not discuss further the distinctive shallow-water morphs of Great Bear Lake.…”

The significance of man-made structures for lake trout spawning in the Great Lakes: are they a viable alternative to natural reefs?

“…Historical inference, based on the association of large catches of spawning condition adult lake trout with specific habitat types, was that lake trout spawned on a wide variety of substrate types, including cobble, rubble, clay, and honeycombed bedrock that were found over a wide range of depths in the Great Lakes including some rivers draining into Lake Superior (Loftus 1957;Goodier 1981;Goodyear et al 1982aGoodyear et al , 1982bGoodyear et al , 1982cGoodyear et al , 1982dThibodeau and Kelso 1990). In contrast, spawning by contemporary lake trout stocks appears restricted to cobble substrates in relatively shallow (< 15 m) water Wagner 1981;Peck 1986;Fitzsimons 1994aFitzsimons , 1995Casselman 1995;Holey et al 1995;Kelso et al 1995;Schreiner et al 1995).…”

“…Alternatively, spawning habitat site selection may have become less diverse as a result of the loss of genetic strains that spawned at greater depths or used spawning habitat other than cobble. Brown et al (1981), Goodier (1981), and Dehring et al (1981) suggested that some of the reported historic variability in spawning habitat selection was the result of multiple strains of lake trout that occurred historically in the Great Lakes. Some historic strains apparently spawned at depths > 15 m to as much as 80-90 m in Lakes Michigan and Huron and up to 180 m in Lake Superior (Thibodeau and Kelso 1990).…”