lake trout

Lake trout
Salvelinus namaycush
Conservation status
Secure
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Salmoniformes
Family:	Salmonidae
Genus:	Salvelinus
Species:	S. namaycush
Binomial name
Salvelinus namaycush (Walbaum, 1792)

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, they can also be variously known as siscowet, paperbellies and leans. Lake trout are prized both as game fish and as food fish.

Range

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. The southern extreme of the Lake trout's range extends into southern New York at Kensico Reservior where a self sustaining population has existed since the 1950's. Lake trout have been introduced into many other parts of the world, mainly into Europe but also into South America and certain parts of Asia. In Canada, approximately 25% of the world's lake trout lakes are found in the province of Ontario. Even at that, only 1% of Ontario's lakes contain lake trout.

Description

Lake trout are the largest of the charrs, the record weighing almost 46.3 kg (102 lb).

Life history

Lake trout are dependent on cold, oxygen-rich waters. They are pelagic during the period of summer stratification in dimictic lakes, often living at depths of 20–60 m (60–200 ft).

The lake trout is a slowly growing fish, typical of oligotrophic waters. It is also very late to mature. Populations are extremely susceptible to overexploitation. Many native lake trout populations have been severely damaged through the combined effects of hatchery stocking (planting) and overharvest.

It is generally accepted that there are two basic types of lake trout populations. 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 size. 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.

A lake trout being held in an angler's hands.

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.^[1] 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. Siscowet populations have rebounded since 1970, with one estimate putting the number in Lake Superior at 100 million.^[2]

Hybrids

Lake trout have been known, very rarely, to hybridize in nature with the brook trout, but such hybrids, known as "splake", are almost invariably reproductively sterile. Splake are also artificially propagated in hatcheries and then planted into lakes in an effort to provide sport fishing opportunities. These fish are easily distinguished from both lake and brook trout by the overlap of markings and coloration. A splake has bright orange fins with white tips and slightly white wormlike markings of a brook trout. Splake also have a longer lake trout jaw, teeth, dark purple back, and orientation of marks like a lake trout

Commercial fishing

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 smaller lakes in northern Canada.

Origin of name

The specific epithet namaycush derives from an indigenous North American name for the species, most likely in one of the Algonquian languages (c.f. Ojibwe: namegos = "lake trout"; namegoshens = "rainbow trout").

In Baltimore, Maryland, the term "lake trout" is used to refer to a popular fast food sandwich of fried Atlantic whiting.^[3]

References

• Salvelinus namaycush (TSN 162002). Integrated Taxonomic Information System. Retrieved on 30 January 2006.

See also

• Lake Trout (band), a rock/ambient/jamband from Baltimore, Maryland.

External links

• Fish-On! - Full Lake Trout Chapter at TheFishingNetwork.com

• Fishbase description of Lake trout