The lake trout is one of the largest members of the Salmonidae family, which encompasses salmon, trout, charr, and whiteﬁsh. This ﬁsh is not actually a “trout” but a charr, and thus a close relative of the brook trout and the arctic charr.
The lake trout was once associated with many variations, some of which have been termed subspecies or strains; some of these no longer exist, and others are deep dwellers that are not commonly known to anglers.
The siscowet or siscoet (which has been listed by some sources as S. siscoet) is one of these; a deep-dwelling (reportedly from 300 to 600 feet) fish of Lake Superior, it is known as the fat lake trout to commercial fishermen because of its extremely oily flesh.
IdentificationThe lake trout has the same moderately elongated shape as does the trout and the salmon. Its tail is moderately forked, more so than those of other charr; its scales are minute; and it has several rows of strong teeth, which are weak, less numerous, or absent in other charr. Its head is generally large, although fast-growing stocked ﬁsh will have small heads in relation to body size, and there is an adipose ﬁn.
Like other charr, the lake trout has white leading edges on all its lower ﬁns and light colored spots on a dark background. The body is typically grayish to brownish, with white or nearly white spots that extend onto the dorsal, the adipose, and the caudal ﬁns. There are no red, black, or haloed spots of any kind.
Coloration is highly variable. Lighter specimens are often the deep-dwelling ﬁsh of light-colored southerly lakes with alewife and smelt forage bases; darker specimens, including some with reddish and orange tones, come from less fertile, tannin-colored northern lakes.
Size/AgeThe all-tackle world record is a 72-pound ﬁsh caught in 1995 at Great Bear Lake, Northwest Territories, although a 74-pounder was caught there in 2001. A 102-pound lake trout was netted in Lake Athabasca, Saskatchewan, in 1961.
In most of its range, a 20-pound lake trout is a very large specimen and is considered a trophy catch; ﬁsh from 30 to 45 pounds are caught every season in a few far-northern waters, most of them being released. The average angler catch in most places weighs 4 to 10 pounds.
Lake trout growth and ages vary from place to place, depending on diet, water temperature, altitude, and genetics. Lake trout in the cold, deep, infertile waters of the north are capable of long life spans. In the more southerly portions of their range, however, they grow more quickly but do not live as long, and in most places they do not live longer than 20 years.
Life history/BehaviorLake trout generally spend their entire lives in lakes, staying deep and often near the bottom at cool levels. They often orient to structure, cluster at tributaries, and wander in search of food, and although they are not school species like some of their forage, they are usually found in groups, often of like-size individuals.
Spawning takes place in the late summer or the early fall over clean, rocky lake bottoms. Rocky shoals or reefs are prominent spawning sites. Unlike other salmonids, lake trout do not make nests. Spawning usually takes place at night, with peak activity occurring after dusk. Eggs hatch early in the following spring. In some populations, spawning occurs every year, whereas in others spawning may occur every other year or less frequently.
FoodThe diet of lake trout varies with the age and the size of the ﬁsh, the locality, and the food available. Food items commonly include zooplankton, insect larvae, small crustaceans, clams, snails, leeches, and various species of ﬁsh, including their own kind. Lake trout feed extensively on such other ﬁsh as whiteﬁsh, grayling, sticklebacks, suckers, and sculpin in the far north or cisco, smelt, and alewives elsewhere.
Other Nameslaker, mackinaw, Great Lakes trout or charr, salmon trout, landlocked salmon, gray trout, great gray trout, mountain trout, tongue, togue, namaycush or masamay-cush, siscowet, fat trout, paperbelly, bank trout, bumper, humper; Cree: namekus, nemakos, nemeks; French: touladi; Inuit: iluuraq, isuuraq.
DistributionThe natural range of the lake trout is across the northern region of North America. It occurs from Quebec, the Maritime Provinces, and Labrador in the east, southerly through New York, and west across the north-central United States and all of Canada to British Columbia and Alaska in the west.
It is widely distributed in the Nunavut, the Yukon, and the Northwest Territories and in the northern sections of other Canadian provinces, including the arctic islands. It has been introduced to northern deep lakes elsewhere in the United States and reintroduced to some parts of its native range, including the Great Lakes in North America.
HabitatOverall, and especially in the southern portions of its range or where introduced south of its native range, the lake trout is an inhabitant of cool waters of large, deep lakes. In far-northern regions it may occur in lakes that are generally shallow and that remain cold all season long, and it may occur in either the shallow or the deep portions of lakes that have large expanses of deep water.
It is also found in large deep rivers or in the lower reaches of rivers, especially in the far north, although it may sometimes move into the tributaries of large southerly lakes to forage. It rarely inhabits brackish water.