Lake trout (Salvelinus namaycush) is a freshwater char living mainly in lakes in northern North America. Other names for it include mackinaw, lake char (or charr), touladi, togue, and grey trout. In Lake Superior, it can also be variously known as siscowet, paperbelly and lean. The lake trout is prized both as a game fish and as a food fish.
From a zoogeographical perspective, lake trout are quite rare. They are native only to the northern parts of North America, principally Canada, but also Alaska and, to some extent, the northeastern United States. Lake trout have been widely introduced into non-native waters in North America and into many other parts of the world, mainly Europe, but also into South America and certain parts of Asia. Although Lake Trout were introduced into Yellowstone National Park's Shoshone, Lewis and Heart lakes legally in the 1890s, they were illegally or accidentally introduced into Yellowstone lake in the 1980s where they are now considered invasive.
Lake trout are the largest of the charrs; the record weighed almost 46.3 kilograms (102 lb) (netted) with a length of 50 inches (127 cm), and 15– to 40-pound fish are not uncommon. The average length is 24-36 inches (61–92 cm). The largest caught on a rod and reel according to the IGFA was 72 pounds (33 kg), caught in Great Bear Lake in 1995 with a length of 59 inches (150 cm).
The lake trout is a slow-growing fish, typical of oligotrophic waters. It is also very late to mature. Populations are extremely susceptible to overfishing. Many native lake trout populations have been severely damaged through the combined effects of hatchery stocking (planting) and over harvest.
Two basic types of lake trout populations are generally accepted. Some lakes do not have pelagic forage fish during the period of summer stratification. In these lakes, lake trout take on a life history known as planktivory. Lake trout in planktivorous populations are highly abundant, grow very slowly and mature at relatively small sizes. In those lakes that do contain deep-water forage, lake trout become piscivorous. Piscivorous lake trout grow much more quickly, mature at a larger size and are less abundant. Notwithstanding differences in abundance, the density of biomass of lake trout is fairly consistent in similar lakes, regardless of whether the lake trout populations they contain are planktivorous or piscivorous.
In Lake Superior, three distinct phenotypes of lake trout persist, commonly known as "siscowet", "paperbelly" and "lean". The distinct groups operate, to some level at least, under genetic control and are not mere environmental adaptations. Siscowet numbers, especially, have become greatly depressed over the years due to a combination of the extirpation of some of the fish's deep water coregonine prey and to overexploitation. Siscowet tend to grow extremely large and fat and attracted great commercial interest in the last century. Their populations have rebounded since 1970, with one estimate putting the number in Lake Superior at 100 million.
Lake trout are known to hybridize in nature with the brook trout, but such hybrids, known as "splake", are normally sterile but self-sustaining populations exist in some lakes. Splake are also artificially propagated in hatcheries, and then planted into lakes in an effort to provide sport-fishing opportunities.
Lake trout were fished commercially in the Great Lakes until lampreys, overharvest and pollution extirpated or severely reduced the stocks. Commercial fisheries still exist in some areas of the Great Lakes and smaller lakes in northern Canada. Commercial fishing by Ojibwe for Lake Trout in the Lake Superior is permitted under various treaties and regulated by the Great Lakes Indian Fish & Wildlife Commission (GLIFWC).
Origin of name
The specific epithet namaycush derives from namekush, a form of the word used in some inland Southern East Cree communities in referring to this species of fish. Other variations found in East Cree are kûkamâs[h], kûkamâw and kûkamesh. Similar cognate words are found in Ojibwe: namegos = "lake trout"; namegoshens = "rainbow trout", literally meaning "little lake trout".
- "Salvelinus namaycush". Integrated Taxonomic Information System. Retrieved 23 November 2013.
- "Salvelinus namaycush Lake trout". Animal Diversity Web. Retrieved 2013-11-23.
- "NAS - Nonindigenous Aquatic Species Lake Trout". US Geological Survey. Retrieved 2013-11-23.
- Munro, Andrew R.; Thomas E. McMahon, James R. Ruzycki (Spring 2006). "Source and Date of Lake Trout Introduction". Yellowstone Science 14 (2).
- "International Game Fish Association-Lake Trout". International Game Fish Association. Retrieved 2013-11-23.
- Burnham-Curtis, M.K. and G.R. Smith, 1994. Osteological evidence of genetic divergence of lake trout (Salvelinus namaycush) in Lake Superior. Copeia (4):845-850.
- Moen, Sharon (December 2002). "Siscowet Trout: A Plague of Riches". Minnesota Sea Grant. Retrieved 20 December 2007.
- Berst, A. H.; Ihssen, P. E., Spangler, G. R., Ayles, G. B., Martin, G. W. (1980). "The splake, a hybrid charr Salvelinus namaycush x S. fontinalis.". In Balon, E. K. Charrs, Salmonid Fishes of the Genus Salvelinus. The Hague: Dr. W. Junk Publishers. pp. 841–887.
- "Why Splake?". Maine.gov Department of Inland Fisheries and Wildlife. Retrieved 2013-11-23.
- "Lake Superior Treaty Fishery". Great Lakes Indian Fish & Wildlife Commission. Retrieved 2013-11-24.
- Berkes, Fikret and Marguerite MacKenzie. "Cree Fish Names from Eastern James Bay, Quebec" in Arctic, Vol. 31, No. 4 (Dec 1978), pp. 489-495
- Weshki-ayaad, Lippert and Gambill. Freelang Ojibwe Dictionary Online. Accessed September 21, 2010.
- Lake trout derby, Geneva, NY Accessed September 29, 2010.